Modelling the solar wind interaction with Mercury by a quasi-neutral hybrid model

NASA Astrophysics Data System (ADS)

Kallio, E.; Janhunen, P.

2003-11-01

Quasi-neutral hybrid model is a self-consistent modelling approach that includes positively charged particles and an electron fluid. The approach has received an increasing interest in space plasma physics research because it makes it possible to study several plasma physical processes that are difficult or impossible to model by self-consistent fluid models, such as the effects associated with the ions’ finite gyroradius, the velocity difference between different ion species, or the non-Maxwellian velocity distribution function. By now quasi-neutral hybrid models have been used to study the solar wind interaction with the non-magnetised Solar System bodies of Mars, Venus, Titan and comets. Localized, two-dimensional hybrid model runs have also been made to study terrestrial dayside magnetosheath. However, the Hermean plasma environment has not yet been analysed by a global quasi-neutral hybrid model.

Coupled two-dimensional edge plasma and neutral gas modeling of tokamak scrape-off-layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maingi, Rajesh

1992-08-01

The objective of this study is to devise a detailed description of the tokamak scrape-off-layer (SOL), which includes the best available models of both the plasma and neutral species and the strong coupling between the two in many SOL regimes. A good estimate of both particle flux and heat flux profiles at the limiter/divertor target plates is desired. Peak heat flux is one of the limiting factors in determining the survival probability of plasma-facing-components at high power levels. Plate particle flux affects the neutral flux to the pump, which determines the particle exhaust rate. A technique which couples a two-dimensionalmore » (2-D) plasma and a 2-D neutral transport code has been developed (coupled code technique), but this procedure requires large amounts of computer time. Relevant physics has been added to an existing two-neutral-species model which takes the SOL plasma/neutral coupling into account in a simple manner (molecular physics model), and this model is compared with the coupled code technique mentioned above. The molecular physics model is benchmarked against experimental data from a divertor tokamak (DIII-D), and a similar model (single-species model) is benchmarked against data from a pump-limiter tokamak (Tore Supra). The models are then used to examine two key issues: free-streaming-limits (ion energy conduction and momentum flux) and the effects of the non-orthogonal geometry of magnetic flux surfaces and target plates on edge plasma parameter profiles.« less

Hippocampus and nucleus accumbens activity during neutral word recognition related to trait physical anhedonia in patients with schizophrenia: an fMRI study.

PubMed

Lee, Jung Suk; Chun, Ji Won; Kang, Jee In; Kang, Dong-Il; Park, Hae-Jeong; Kim, Jae-Jin

2012-07-30

Emotional memory dysfunction may be associated with anhedonia in schizophrenia. This study aimed to investigate the neurobiological basis of emotional memory and its relationship with anhedonia in schizophrenia specifically in emotional memory relate brain regions of interest (ROIs) including the amygdala, hippocampus, nucleus accumbens, and ventromedial prefrontal cortex. Fourteen patients with schizophrenia and 16 healthy subjects performed a word-image associative encoding task, during which a neutral word was presented with a positive, neutral, or control image. Subjects underwent functional magnetic resonance imaging while performing the recognition task. Correlation analyses were performed between the percent signal change (PSC) in the ROIs and the anhedonia scores. We found no group differences in recognition accuracy and reaction time. The PSC of the hippocampus in the positive and neutral conditions, and the PSC in the nucleus accumbens in the control condition, appeared to be negatively correlated with the Physical Anhedonia Scale (PAS) scores in patients with schizophrenia, while significant correlations with the PAS scores were not observed in healthy subjects. This study provides further evidences of the role of the hippocampus and nucleus accumbens in trait physical anhedonia and possible associations between emotional memory deficit and trait physical anhedonia in patients with schizophrenia. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Two-Dimensional Arrays of Neutral Atom Quantum Gates

DTIC Science & Technology

2012-10-20

Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS quantum computing , Rydberg atoms, entanglement Mark Saffman University of...Nature Physics, (01 2009): 0. doi: 10.1038/nphys1178 10/19/2012 9.00 K. Mølmer, M. Saffman. Scaling the neutral-atom Rydberg gate quantum computer by...Saffman, E. Brion, K. Mølmer. Error Correction in Ensemble Registers for Quantum Repeaters and Quantum Computers , Physical Review Letters, (3 2008): 0

Lexical neutrality in environmental health research: Reflections on the term walkability.

PubMed

Hajna, Samantha; Ross, Nancy A; Griffin, Simon J; Dasgupta, Kaberi

2017-12-08

Neighbourhood environments have important implications for human health. In this piece, we reflect on the environments and health literature and argue that precise use of language is critical for acknowledging the complex and multifaceted influence that neighbourhood environments may have on physical activity and physical activity-related outcomes. Specifically, we argue that the term "neighbourhood walkability", commonly used in the neighbourhoods and health literature, constrains recognition of the breadth of influence that neighbourhood environments might have on a variety of physical activity behaviours. The term draws attention to a single type of physical activity and implies that a universal association exists when in fact the literature is quite mixed. To maintain neutrality in this area of research, we suggest that researchers adopt the term "neighbourhood physical activity environments" for collective measures of neighbourhood attributes that they wish to study in relation to physical activity behaviours or physical activity-related health outcomes.

Can policy ameliorate socioeconomic inequities in obesity and obesity-related behaviours? A systematic review of the impact of universal policies on adults and children.

PubMed

Olstad, D L; Teychenne, M; Minaker, L M; Taber, D R; Raine, K D; Nykiforuk, C I J; Ball, K

2016-12-01

This systematic review examined the impact of universal policies on socioeconomic inequities in obesity, dietary and physical activity behaviours among adults and children. PRISMA-Equity guidelines were followed. Database searches spanned from 2004 to August 2015. Eligible studies assessed the impact of universal policies on anthropometric, dietary or physical activity-related outcomes in adults or children according to socioeconomic position. Thirty-six studies were included. Policies were classified as agentic, agento-structural or structural, and their impact on inequities was rated as positive, neutral, negative or mixed according to the dominant associations observed. Most policies had neutral impacts on obesity-related inequities regardless of whether they were agentic (60% neutral), agento-structural (68% neutral) or structural (67% neutral). The proportion of positive impacts was similar across policy types (10% agentic, 18% agento-structural and 11% structural), with some differences for negative impacts (30% agentic, 14% agento-structural and 22% structural). The majority of associations remained neutral when stratified by participant population, implementation level and socioeconomic position measures and by anthropometric and behavioural outcomes. Fiscal measures had consistently neutral or positive impacts on inequities. Findings suggest an important role for policy in addressing obesity in an equitable manner and strengthen the case for implementing a broad complement of policies spanning the agency-structure continuum. © 2016 World Obesity Federation.

77 FR 69598 - Meeting of the Defense Advisory Committee on Women in the Services (DACOWITS)

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-20

... update briefing on their gender neutral standards, and the Committee will receive a DoD update on sexual...--U.S. Army Update on Gender Neutral Physical Standards. --Briefing--DoD Update on Sexual Assault...

Insulin pumps and insulin quality--requirements and problems.

PubMed

Brange, J; Havelund, S

1983-01-01

In developing insulin solution suitable for delivery devices the chemical and biological stability, as well as the physical stability, must be taken into consideration. Addition of certain mono- and disaccharides increases the physical stability of neutral insulin solutions, but concurrently the chemical and biological stability decrease to an unacceptable degree. Addition of Ca-ions in low concentrations offers a physiologically acceptable method for stabilizing neutral insulin solutions against heat precipitation without affecting the quality, including the chemical and biological stability.

Neutral decays of {eta}{sup '} at WASA-at-COSY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duniec, David; Jany, Benedykt R.; IKP-2 Forschungszentrum Juelich, 52428 Juelich

2007-11-07

The status and some of the goals of the {eta}{sup '} physics program at WASA-at-COSY with regards to neutral hadronic decays are presented. Very preliminary results of a test run from WASA-at-COSY in May 2007 are presented.

Identification of minute damage in composite bridge structures equipped with fiber optic sensors using the location of neutral axis and finite element analysis

NASA Astrophysics Data System (ADS)

Li, Xi; Glisic, Branko

2016-04-01

By definition, the neutral axis of a loaded composite beam structure is the curve along which the section experiences zero bending strain. When no axial loading is present, the location of the neutral axis passes through the centroid of stiffness of the beam cross-section. In the presence of damage, the centroid of stiffness, as well as the neutral axis, shift from the healthy position. The concept of neutral axis can be widely applied to all beam-like structures. According to literature, a change in location of the neutral axis can be associated with damage in the corresponding cross-section. In this paper, the movement of neutral axis near locations of minute damage in a composite bridge structure was studied using finite element analysis and experimental results. The finite element model was developed based on a physical scale model of a composite simply-supported structure with controlled minute damage in the reinforced concrete deck. The structure was equipped with long-gauge fiber optic strain and temperature sensors at a healthy reference location as well as two locations of damage. A total of 12 strain sensors were installed during construction and used to monitor the structure during various loading events. This paper aims to explain previous experimental results which showed that the observed positions of neutral axis near damage locations were higher than the predicted healthy locations in some loading events. Analysis has shown that finite element analysis has potential to simulate and explain the physical behavior of the test structure.

Acute nonhypothermic exposure to cold impedes motor skill performance in video gaming compared to thermo-neutral and hot conditions.

PubMed

Edwards, Andrew M; Crowther, Robert G; Morton, R Hugh; Polman, Remco C

2011-02-01

The study examined whether or not acute exposure to unfamiliar hot or cold conditions impairs performance of highly skilled coordinative activities and whether prior physical self-efficacy beliefs were associated with task completion. Nineteen volunteers completed both Guitar Hero and Archery activities as a test battery using the Nintendo Wii console in cold (2 degrees C), neutral (20 degrees C), and hot (38 degrees C) conditions. Participants all completed physical self-efficacy questionnaires following experimental familiarization. Performances of both Guitar Hero and Archery significantly decreased in the cold compared with the neutral condition. The cold trial was also perceived as the condition requiring both greater concentration and effort. There was no association between performance and physical self-efficacy. Performance of these coordinative tasks was compromised by acute (nonhypothermic) exposure to cold; the most likely explanation is that the cold condition presented a greater challenge to attentional processes as a form of environmental distraction.

Structural and physical properties of collagen extracted from moon jellyfish under neutral pH conditions.

PubMed

Miki, Ayako; Inaba, Satomi; Baba, Takayuki; Kihira, Koji; Fukada, Harumi; Oda, Masayuki

2015-01-01

We extracted collagen from moon jellyfish under neutral pH conditions and analyzed its amino acid composition, secondary structure, and thermal stability. The content of hydroxyproline was 4.3%, which is lower than that of other collagens. Secondary structure analysis using circular dichroism (CD) showed a typical collagen helix. The thermal stability of this collagen at pH 3.0 was lower than those from fish scale and pig skin, which also correlates closely with jellyfish collagen having lower hydroxyproline content. Because the solubility of jellyfish collagen used in this study at neutral pH was quite high, it was possible to analyze its structural and physical properties under physiological conditions. Thermodynamic analysis using CD and differential scanning calorimetry showed that the thermal stability at pH 7.5 was higher than at pH 3.0, possibly due to electrostatic interactions. During the process of unfolding, fibrillation would occur only at neutral pH.

Driven waves in a two-fluid plasma

NASA Astrophysics Data System (ADS)

Roberge, W. G.; Ciolek, Glenn E.

2007-12-01

We study the physics of wave propagation in a weakly ionized plasma, as it applies to the formation of multifluid, magnetohydrodynamics (MHD) shock waves. We model the plasma as separate charged and neutral fluids which are coupled by ion-neutral friction. At times much less than the ion-neutral drag time, the fluids are decoupled and so evolve independently. At later times, the evolution is determined by the large inertial mismatch between the charged and neutral particles. The neutral flow continues to evolve independently; the charged flow is driven by and slaved to the neutral flow by friction. We calculate this driven flow analytically by considering the special but realistic case where the charged fluid obeys linearized equations of motion. We carry out an extensive analysis of linear, driven, MHD waves. The physics of driven MHD waves is embodied in certain Green functions which describe wave propagation on short time-scales, ambipolar diffusion on long time-scales and transitional behaviour at intermediate times. By way of illustration, we give an approximate solution for the formation of a multifluid shock during the collision of two identical interstellar clouds. The collision produces forward and reverse J shocks in the neutral fluid and a transient in the charged fluid. The latter rapidly evolves into a pair of magnetic precursors on the J shocks, wherein the ions undergo force-free motion and the magnetic field grows monotonically with time. The flow appears to be self-similar at the time when linear analysis ceases to be valid.

Films based on neutralized chitosan citrate as innovative composition for cosmetic application.

PubMed

Libio, Illen C; Demori, Renan; Ferrão, Marco F; Lionzo, Maria I Z; da Silveira, Nádya P

2016-10-01

In this work, citrate and acetate buffers, were investigated as neutralizers to chitosan salts in order to provide biocompatible and stable films. To choose the appropriate film composition for this study, neutralized chitosan citrate and acetate films, with and without the plasticizer glycerol, were prepared and characterized by thickness, moisture content, degree of swelling, total soluble matter in acid medium, simultaneous thermal analysis and differential scanning calorimetry. Chitosan films neutralized in citrate buffer showed greater physical integrity resulted from greater thicknesses, lower moisture absorbance, lower tendency to solubility in the acid medium, and better swelling capacities. According to thermal analyses, these films had higher interaction with water which is considered an important feature for cosmetic application. Since the composition prepared in citrate buffer without glycerol was considered to present better physical integrity, it was applied to investigate hyaluronic acid release in a skin model. Skins treated with those films, with or without hyaluronic acid, show stratum corneum desquamation and hydration within 10min. The results suggest that the neutralized chitosan citrate film prepared without glycerol promotes a cosmetic effect for skin exfoliation in the presence or absence of hyaluronic acid. Copyright © 2016 Elsevier B.V. All rights reserved.

Prediction of Physical Properties of Nanofiltration Membranes for Neutral and Charged Solutes

EPA Science Inventory

Two commercial nanofiltration (NF) membranes viz., NF 300 MWCO and NF 250 MWCO were used for neutral and charged solute species viz., glucose, sodium chloride and magnesium chloride to investigate their rejection rates using Donnan steric pore model (DSPM) and DSPM-dielectric exc...

Discrete symmetries with neutral mesons

NASA Astrophysics Data System (ADS)

Bernabéu, José

2018-01-01

Symmetries, and Symmetry Breakings, in the Laws of Physics play a crucial role in Fundamental Science. Parity and Charge Conjugation Violations prompted the consideration of Chiral Fields in the construction of the Standard Model, whereas CP-Violation needed at least three families of Quarks leading to Flavour Physics. In this Lecture I discuss the Conceptual Basis and the present experimental results for a Direct Evidence of Separate Reversal-in-Time T, CP and CPT Genuine Asymmetries in Decaying Particles like Neutral Meson Transitions, using Quantum Entanglement and the Decay as a Filtering Measurement. The eight transitions associated to the Flavour-CP eigenstate decay products of entangled neutral mesons have demonstrated with impressive significance a separate evidence of TRV and CPV in Bd-physics, whereas a CPTV asymmetry shows a 2σ effect interpreted as an upper limit. Novel CPTV observables are discussed for K physics at KLOE-2, including the difference between the semileptonic asymmetries from KL and KS, the ratios of double decay rate Intensities to Flavour-CP eigenstate decay products and the ω-effect. Their observation would lead to a change of paradigm beyond Quantum Field Theory, however there is nothing in Quantum Mechanics forbidding CPTV.

Skin penetration and retention of L-ascorbic acid 2-phosphate using multilamellar vesicles.

PubMed

Yoo, Juno; Shanmugam, Srinivasan; Song, Chung-Kil; Kim, Dae-Duk; Choi, Han-Gon; Yong, Chul-Soon; Woo, Jong-Soo; Yoo, Bong Kyu

2008-12-01

Transdermal formulation of L-ascorbic acid 2-phosphate magnesium salt (A2P) was prepared using multilamellar vesicles (MLV). A2P was either physically mixed with or entrapped into three different MLVs of neutral, cationic, and anionic liposome vesicles. For the preparation of neutral MLVs, phosphatidylcholine (PC) and cholesterol (CH) were used. For cationic and anionic MLVs, dioleoyl-trimethylammonium-propane and dimyristoyl glycerophosphate were added as surface charge inducers, respectively, in addition to PC and CH. Particle size of the three A2P-loaded MLVs was submicron, and polydispersity index revealed homogenous distribution of the prepared MLVs except neutral ones. Skin penetration study with hairless mouse skin showed that both physical mixtures of A2P with empty MLVs and A2P-loaded MLVs increased penetration of the drug compared to aqueous A2P solution. During the penetration, however, significant amount of the drug was metabolized into L-ascorbic acid, which has no beneficial effect on stimulation of hair growth. Out of the physical mixtures and A2P-loaded MLVs tested, physical mixture of A2P with empty cationic MLV resulted in the greatest skin penetration and retention in hairless mouse skin.

Observability, Visualizability and the Question of Metaphysical Neutrality

NASA Astrophysics Data System (ADS)

Wolff, Johanna

2015-09-01

Theories in fundamental physics are unlikely to be ontologically neutral, yet they may nonetheless fail to offer decisive empirical support for or against particular metaphysical positions. I illustrate this point by close examination of a particular objection raised by Wolfgang Pauli against Hermann Weyl. The exchange reveals that both parties to the dispute appeal to broader epistemological principles to defend their preferred metaphysical starting points. I suggest that this should make us hesitant to assume that in deriving metaphysical conclusions from physical theories we place our metaphysical theories on a purely empirical foundation. The metaphysics within a particular physical theory may well be the result of a priori assumptions in the background, not particular empirical findings.

Analysis of Plasma Communication Schemes for Hypersonic Vehicles: Final Report

DTIC Science & Technology

2009-02-01

repel the more mobile species. In this way quasi -neutrality can be maintained in the plasma. The potential drops near the conducting surfaces are of... potential VM cannot be determined from a quasi - neutral diffusion theory and depends on the details of sheath physics at electrode surfaces. In the...the mid potential VM, which cannot be determined by simple quasi -neutral fluid theory, is in general a function of L. This L dependence, which

Conceptual design of the neutral beamline for TPX long pulse operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, K.E.; Dahlgren, F.; Fan, H.M.

The Tokamak Physics Experiment (TPX) will require a minimum of 8.0 megawatts of Neutral Beam beating power to be injected into the plasma for pulse lengths up to one thousand (1000) seconds to meet the experimental objectives. The Neutral Beam Injection System (NBIS) for initial operation on TPX will consist of one neutral beamline (NBL) with three Ion sources. Provisions will be made for a total of three NBLs. The NBIS will provide S.S MW of 120 keV D{sup 0} and 2.S MW of partial-energy D{sup 0} at 60 keV and 40 keV. The system also provides for measuring themore » neutral beam power, limits excess cold gas from entering the torus, and provides independent power, control, and protection for each individual ion source and accelerating structure. The Neutral Beam/Torus Connecting Duct (NB/TCD) includes a vacuum valve, an electrical insulating break, alignment bellows, vacuum seals, internal energy absorbing protective elements, beam diagnostics and bakeout capability. The NBL support structure will support the NBL, which will weigh approximately 80 tons at the proper elevation and withstand a seismic event. The NBIS currently operational on the Tokamak Fusion Test Reactor (TFTR) at the Princeton Plasma Physics Laboratory (PPPL) is restricted to injection pulse lengths of two (2) seconds by the limited capability of various energy absorbers. This paper describes the modifications and improvements which will be implemented for the TFTR Neutral Beamlines and the NB/TCD to satisfy the TPX requirements.« less

The influence of self-generated emotions on physical performance: an investigation of happiness, anger, anxiety, and sadness.

PubMed

Rathschlag, Marco; Memmert, Daniel

2013-04-01

The present study examined the relationship between self-generated emotions and physical performance. All participants took part in five emotion induction conditions (happiness, anger, anxiety, sadness, and an emotion-neutral state) and we investigated their influence on the force of the finger musculature (Experiment 1), the jump height of a counter-movement jump (Experiment 2), and the velocity of a thrown ball (Experiment 3). All experiments showed that participants could produce significantly better physical performances when recalling anger or happiness emotions in contrast to the emotion-neutral state. Experiments 1 and 2 also revealed that physical performance in the anger and the happiness conditions was significantly enhanced compared with the anxiety and the sadness conditions. Results are discussed in relation to the Lazarus (1991, 2000a) cognitive-motivational-relational (CMR) theory framework.

Thermodynamic neutral density: A new physically-based, energy-constrained, materially conserved neutral density variable for quantifying mixing and tracking water masses in the ocean

NASA Astrophysics Data System (ADS)

Tailleux, R.

2016-02-01

A new materially-conserved quasi-neutral density variable has been constructed, called thermodynamic neutral density. It is composed of two parts. The first part is the Lorenz reference density entering Lorenz theory of available potential energy, which can be interpreted as the potential density of a fluid parcel referenced to the pressure it would have in Lorenz reference state of minimum potential energy. The second part is an empirical correction for pressure, which can be suitably chosen to make thermodynamic neutral density a very good approximation of Jackett and McDougall (1997) neutral density over most of the ocean water masses for which the latter is defined. Thermodynamic neutral density possesses many advantages over the empirically constructed Jackett and McDougall (1997) neutral density: 1) it is physically-based; 2) it is easily computed using fast and efficient methods for arbitrary states of the ocean, not just the present state, using the recently developed methodology by Saenz et al. (2015); 3) it is exactly neutral in a state of rest, and approximately neutral in the present ocean; 4) it is exactly materially conserved (it is a function of salinity and potential temperature only) and not plagued by unphysical nonmaterial effects, so can be used unambiguously to define and diagnose diapycnal and isopycnal mixing; 5) it is based on available potential energy, and therefore is the most suitable variable to discuss the energy cost of adiabatic stirring; 6) it is the variable that should be used to define the isopycnal and diapycnal directions in rotated diffusion tensor, as it can be shown that using the directions defined by the local neutral tangent plane as currently done causes spurious destruction of water masses. References: J. A. Saenz, R. Tailleux, E.D. Butler, G.O. Hughes, and K.I.C. Oliver, 2015: Estimating Lorenz's reference state in an ocean with a nonlinear equation of state for seawater. J. Phys. Oceanogr., 45, 1242—1257

Dynamics of HIV neutralization by a microbicide formulation layer: biophysical fundamentals and transport theory.

PubMed

Geonnotti, Anthony R; Katz, David F

2006-09-15

Topical microbicides are an emerging HIV/AIDS prevention modality. Microbicide biofunctionality requires creation of a chemical-physical barrier against HIV transmission. Barrier effectiveness derives from properties of the active compound and its delivery system, but little is known about how these properties translate into microbicide functionality. We developed a mathematical model simulating biologically relevant transport and HIV-neutralization processes occurring when semen-borne virus interacts with a microbicide delivery vehicle coating epithelium. The model enables analysis of how vehicle-related variables, and anti-HIV compound characteristics, affect microbicide performance. Results suggest HIV neutralization is achievable with postcoital coating thicknesses approximately 100 mum. Increased microbicide concentration and potency hasten viral neutralization and diminish penetration of infectious virus through the coating layer. Durable vehicle structures that restrict viral diffusion could provide significant protection. Our findings demonstrate the need to pair potent active ingredients with well-engineered formulation vehicles, and highlight the importance of the dosage form in microbicide effectiveness. Microbicide formulations can function not only as drug delivery vehicles, but also as physical barriers to viral penetration. Total viral neutralization with 100-mum-thin coating layers supports future microbicide use against HIV transmission. This model can be used as a tool to analyze diverse factors that govern microbicide functionality.

Flexible Work Strategies | Climate Neutral Research Campuses | NREL

Science.gov Websites

physical resources through shared offices and hotelling. Employees take turns using physical office and lab , telecommuting, and similar strategies make the most of limited physical space and, in some cases, avoid new construction. Hotelling is a popular option under which employees take turns using physical office and lab

Electric-current Neutralization, Magnetic Shear, and Eruptive Activity in Solar Active Regions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yang; Sun, Xudong; Török, Tibor

The physical conditions that determine whether or not solar active regions (ARs) produce strong flares and coronal mass ejections (CMEs) are not yet well understood. Here, we investigate the association between electric-current neutralization, magnetic shear along polarity inversion lines (PILs), and eruptive activity in four ARs: two emerging and two well-developed ones. We find that the CME-producing ARs are characterized by a strongly non-neutralized total current, while the total current in the ARs that did not produce CMEs is almost perfectly neutralized. The difference in the PIL shear between these two groups is much less pronounced, which suggests that themore » degree of current neutralization may serve as a better proxy for assessing the ability of ARs to produce CMEs.« less

Signals from flavor changing scalar currents at the future colliders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atwood, D.; Reina, L.; Soni, A.

1996-11-22

We present a general phenomenological analysis of a class of Two Higgs Doublet Models with Flavor Changing Neutral Currents arising at the tree level. The existing constraints mainly affect the couplings of the first two generations of quarks, leaving the possibility for non negligible Flavor Changing couplings of the top quark open. The next generation of lepton and hadron colliders will offer the right environment to study the physics of the top quark and to unravel the presence of new physics beyond the Standard Model. In this context we discuss some interesting signals from Flavor Changing Scalar Neutral Currents.

Learning Activity Package, Physical Science. LAP Numbers 5, 6, and 7.

ERIC Educational Resources Information Center

Williams, G. J.

These three units of the Learning Activity Packages (LAPs) for individualized instruction in physical science cover the physical and chemical properties of water, dehydration of crystals, solutions, acidity, strong and weak bases, neutral properties of salts, amorphous forms of carbon, hydrocarbons, and petroleum products. Each unit contains a…

On coupling fluid plasma and kinetic neutral physics models

DOE PAGES

Joseph, I.; Rensink, M. E.; Stotler, D. P.; ...

2017-03-01

The coupled fluid plasma and kinetic neutral physics equations are analyzed through theory and simulation of benchmark cases. It is shown that coupling methods that do not treat the coupling rates implicitly are restricted to short time steps for stability. Fast charge exchange, ionization and recombination coupling rates exist, even after constraining the solution by requiring that the neutrals are at equilibrium. For explicit coupling, the present implementation of Monte Carlo correlated sampling techniques does not allow for complete convergence in slab geometry. For the benchmark case, residuals decay with particle number and increase with grid size, indicating that theymore » scale in a manner that is similar to the theoretical prediction for nonlinear bias error. Progress is reported on implementation of a fully implicit Jacobian-free Newton–Krylov coupling scheme. The present block Jacobi preconditioning method is still sensitive to time step and methods that better precondition the coupled system are under investigation.« less

Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission

DOE PAGES

Chrystal, Colin; Burrell, Keith H.; Grierson, Brian A.; ...

2015-10-20

Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in-situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination diagnostic (CER) at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain informationmore » about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. Lastly, the methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access.« less

Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission

NASA Astrophysics Data System (ADS)

Chrystal, C.; Burrell, K. H.; Grierson, B. A.; Pace, D. C.

2015-10-01

Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination (CER) diagnostic at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain information about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. The methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access.

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

NASA Astrophysics Data System (ADS)

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.

Beyond ITER: neutral beams for a demonstration fusion reactor (DEMO) (invited).

PubMed

McAdams, R

2014-02-01

In the development of magnetically confined fusion as an economically sustainable power source, International Tokamak Experimental Reactor (ITER) is currently under construction. Beyond ITER is the demonstration fusion reactor (DEMO) programme in which the physics and engineering aspects of a future fusion power plant will be demonstrated. DEMO will produce net electrical power. The DEMO programme will be outlined and the role of neutral beams for heating and current drive will be described. In particular, the importance of the efficiency of neutral beam systems in terms of injected neutral beam power compared to wallplug power will be discussed. Options for improving this efficiency including advanced neutralisers and energy recovery are discussed.

Impact ionization study

NASA Technical Reports Server (NTRS)

Whipple, E. C., Jr.

1982-01-01

The impact ionization phenomenon which was observed on certain spacecraft was studied. The phenomenon occurs when a neutral atom, molecule, or ion strikes a surface with sufficient kinetic energy that either the incident neutral or atoms on the surface are ionized, with subsequent escape of ions and/or electrons. The released ions and electrons can interfere with measurements on the spacecraft by confusing interpretation of the data. On the other hand, there is the possibility that the effect could be developed into a diagnostic tool for investigating neutral atmospheric species or for studying physical processes on spacecraft surfaces.

A Massively Parallel Particle Code for Rarefied Ionized and Neutral Gas Flows in Earth and Planetary Atmospheres, Ionospheres and Magnetospheres

NASA Technical Reports Server (NTRS)

Combi, Michael R.

2004-01-01

In order to understand the global structure, dynamics, and physical and chemical processes occurring in the upper atmospheres, exospheres, and ionospheres of the Earth, the other planets, comets and planetary satellites and their interactions with their outer particles and fields environs, it is often necessary to address the fundamentally non-equilibrium aspects of the physical environment. These are regions where complex chemistry, energetics, and electromagnetic field influences are important. Traditional approaches are based largely on hydrodynamic or magnetohydrodynamic MHD) formulations and are very important and highly useful. However, these methods often have limitations in rarefied physical regimes where the molecular collision rates and ion gyrofrequencies are small and where interactions with ionospheres and upper neutral atmospheres are important.

The Effects of Social Behavior on Fourth and Fifth Grade Girls' Perceptions of Physically Attractive and Unattractive Peers.

ERIC Educational Resources Information Center

Duncan-Bazil, Lisa; Foster, Sharon L.

Despite abundant research relating physical attractiveness and social skill, no studies have systematically assessed the influence of social behavior on perceived attractiveness. This study experimentally investigated how exposure to positive, negative, and neutral childhood behaviors influences ratings of physical attractiveness and other social…

Dissociation between morality and disgust: an event-related potential study.

PubMed

Yang, Qun; Li, An; Xiao, Xiao; Zhang, Ye; Tian, Xuehong

2014-10-01

This study explored the neural correlates of morality and disgust, particularly, how the mechanisms that mediate our avoidance of physically disgusting and morally abhorrent behaviors are neurologically dissociated during the time-course of processing. Twelve participants were asked to judge the acceptability of different types of behaviors, which varied in their level of moral wrongness and physical disgust, while event-related potentials (ERPs) were recorded. The main results showed that the two morally wrong conditions elicited greater amplitudes of P300-400 at frontal sites than the neutral condition and the physically disgusting, but not morally wrong, condition. The physically disgusting conditions (with and without moral content) elicited significantly more positive deflections in the 500-600 ms timeframe than the neutral condition at central-posterior sites. These findings indicate that our aversion to harmful substances in the physical environment and offensive behaviors in the social environment may be neurologically dissociable in the temporal dimension. Furthermore, the detection of moral violations may be processed earlier in time than that of physical disgust. Copyright © 2014 Elsevier B.V. All rights reserved.

This person is saying bad things about you: The influence of physically and socially threatening context information on the processing of inherently neutral faces.

PubMed

Klein, Fabian; Iffland, Benjamin; Schindler, Sebastian; Wabnitz, Pascal; Neuner, Frank

2015-12-01

Recent studies have shown that the perceptual processing of human faces is affected by context information, such as previous experiences and information about the person represented by the face. The present study investigated the impact of verbally presented information about the person that varied with respect to affect (neutral, physically threatening, socially threatening) and reference (self-referred, other-referred) on the processing of faces with an inherently neutral expression. Stimuli were presented in a randomized presentation paradigm. Event-related potential (ERP) analysis demonstrated a modulation of the evoked potentials by reference at the EPN (early posterior negativity) and LPP (late positive potential) stage and an enhancing effect of affective valence on the LPP (700-1000 ms) with socially threatening context information leading to the most pronounced LPP amplitudes. We also found an interaction between reference and valence with self-related neutral context information leading to more pronounced LPP than other related neutral context information. Our results indicate an impact of self-reference on early, presumably automatic processing stages and also a strong impact of valence on later stages. Using a randomized presentation paradigm, this study confirms that context information affects the visual processing of faces, ruling out possible confounding factors such as facial configuration or conditional learning effects.

Theoretical and Experimental Beam Plasma Physics (TEBPP)

NASA Technical Reports Server (NTRS)

Roberts, W. T.

1985-01-01

The theoretical and experimental beam plasma physics (TEBPP) consists of a package of five instruments to measure electric and magnetic fields, plasma density and temperature, neutral density, photometric emissions, and energetic particle spectra during firings of the particle injector (SEPAC) electron beam. The package is deployed on a maneuverable boom (or RMS) and is used to measure beam characteristics and induced perturbations in the near field ( 10 m) and mid field (10 m to 100 m) along the electron beam. The TEBPP package will be designed to investigate induced oscillations and induced electromagnetic mode waves, neutral and ion density and temperature effects, and beam characteristics as a function of axial distance.

Theoretical and Experimental Beam Plasma Physics (TEBPP)

NASA Technical Reports Server (NTRS)

Roberts, B.

1986-01-01

The theoretical and experimental beam plasma physics (TEBPP) consists of a package of five instruments to measure electric and magnetic fields, plasma density and temperature, neutral density, photometric emissions, and energetic particle spectra during firings of the particle injector (SEPAC) electron beam. The package is developed on a maneuverable boom (or RMS) and is used to measure beam characteristics and induced perturbations field ( 10 m) and mid field ( 10 m to 100 m) along the electron beam. The TEBPP package will be designed to investigate induced oscillations and induced electromagnetic mode waves, neutral and ion density and temperature effects, and beam characteristics as a function of axial distance.

Atomic and Molecular Spectroscopic Studies of the DIII-D Neutral Beam Ion Source and Neutralizer

NASA Astrophysics Data System (ADS)

Crowley, B.; Rauch, J.; Scoville, J. T.; Sharma, S. K.; Choksi, B.

2015-11-01

The neutral beam system is interesting in that it comprises two distinct low temperature plasmas. Firstly, the ion source is typically a filament or RF driven plasma from which ions are extracted by a high voltage accelerator grid system. Secondly the neutralizer is essentially a low temperature plasma system with the beam serving as the primary ionization source and the neutralizer walls serving as conducting boundaries. Atomic spectroscopy of Doppler shifted D-alpha light emanating from the fast atoms is studied to determine the composition of the source and the divergence of the beam. Molecular spectroscopy involves measuring fine structure in electron-vibrational rotational bands. The technique has applications in low temperature plasmas and here it is used to determine gas temperature in the neutralizer. We describe the experimental set-up and the physics model used to relate the spectroscopic data to the plasma parameters and we present results of recent experiments exploring how to increase neutralization efficiency. Supported by the US DOE under DE-FC02-04ER54698.

Do STEM fields need a makeover?: The effect of role model femininity on men and women's interest in STEM

NASA Astrophysics Data System (ADS)

Howard, Carolynn

Women continue to be underrepresented in science, technology, engineering, and mathematics (STEM) fields. This lack of women is problematic because it diminishes perspective, input, and expertise that women could provide. Consequently, this thesis examined the benefits of exposure to peer role models for increasing women's interest in STEM, which may ultimately lead more women to enter STEM fields. The role model research to date has amassed considerable evidence showing that role model exposure is beneficial; yet, questions still remain about what makes these role models effective. Accordingly, this thesis investigated whether feminine female role models increase women's interest in STEM and improve their perceptions of female STEM role models relative to "neutral" female role models. Across three experiments men and women were exposed to role models and their interest in STEM was measured. All experiments exposed participants to one of three articles about a peer role model (a female role model who embodies femininity (e.g. wears makeup), a female role model who has gender neutral qualities/behaviors [e.g., works hard], or a male role model who embodies neutral traits) and Experiments 2 and 3 had a fourth control condition in which participants read about the history of SDSU (a control condition). In the first two experiments interest in physics was measured using an adapted version of the STEM Career Interest Survey (CIS). Experiment 3 used an adapted version of the STEM CIS scale, but measured overall interest in STEM by including subscales for each of the four STEM areas with a composite score serving as the primary dependent variable. Experiments 1 and 2 demonstrated that women's interest in physics was no different than men's after exposure to a feminine female role model compared to a neutral female and neutral male role model. Furthermore, women's interest in physics was greater in the feminine condition compared to all other conditions for the first two experiments, thus demonstrating that a competent feminine role model may be useful in piquing women's interest in physics. Experiment 3, however, did not display this pattern for women's interest in STEM overall.

Simulating Coupling Complexity in Space Plasmas: First Results from a new code

NASA Astrophysics Data System (ADS)

Kryukov, I.; Zank, G. P.; Pogorelov, N. V.; Raeder, J.; Ciardo, G.; Florinski, V. A.; Heerikhuisen, J.; Li, G.; Petrini, F.; Shematovich, V. I.; Winske, D.; Shaikh, D.; Webb, G. M.; Yee, H. M.

2005-12-01

The development of codes that embrace 'coupling complexity' via the self-consistent incorporation of multiple physical scales and multiple physical processes in models has been identified by the NRC Decadal Survey in Solar and Space Physics as a crucial necessary development in simulation/modeling technology for the coming decade. The National Science Foundation, through its Information Technology Research (ITR) Program, is supporting our efforts to develop a new class of computational code for plasmas and neutral gases that integrates multiple scales and multiple physical processes and descriptions. We are developing a highly modular, parallelized, scalable code that incorporates multiple scales by synthesizing 3 simulation technologies: 1) Computational fluid dynamics (hydrodynamics or magneto-hydrodynamics-MHD) for the large-scale plasma; 2) direct Monte Carlo simulation of atoms/neutral gas, and 3) transport code solvers to model highly energetic particle distributions. We are constructing the code so that a fourth simulation technology, hybrid simulations for microscale structures and particle distributions, can be incorporated in future work, but for the present, this aspect will be addressed at a test-particle level. This synthesis we will provide a computational tool that will advance our understanding of the physics of neutral and charged gases enormously. Besides making major advances in basic plasma physics and neutral gas problems, this project will address 3 Grand Challenge space physics problems that reflect our research interests: 1) To develop a temporal global heliospheric model which includes the interaction of solar and interstellar plasma with neutral populations (hydrogen, helium, etc., and dust), test-particle kinetic pickup ion acceleration at the termination shock, anomalous cosmic ray production, interaction with galactic cosmic rays, while incorporating the time variability of the solar wind and the solar cycle. 2) To develop a coronal mass ejection and interplanetary shock propagation model for the inner and outer heliosphere, including, at a test-particle level, wave-particle interactions and particle acceleration at traveling shock waves and compression regions. 3) To develop an advanced Geospace General Circulation Model (GGCM) capable of realistically modeling space weather events, in particular the interaction with CMEs and geomagnetic storms. Furthermore, by implementing scalable run-time supports and sophisticated off- and on-line prediction algorithms, we anticipate important advances in the development of automatic and intelligent system software to optimize a wide variety of 'embedded' computations on parallel computers. Finally, public domain MHD and hydrodynamic codes had a transforming effect on space and astrophysics. We expect that our new generation, open source, public domain multi-scale code will have a similar transformational effect in a variety of disciplines, opening up new classes of problems to physicists and engineers alike.

Collisional Thermalization in Strongly Coupled Ultracold Neutral Plasmas

DTIC Science & Technology

2017-01-25

Beaumont, TX (4/16). “Studying Strongly Coupled Systems with Ultracold Plasmas," Department of Physics and Astronomy Colloquium, University of South...Alabama, Mobile, AL (11/15). “Collective Modes and Correlations in Strongly Coupled Ultracold Plasmas," Department of Physics and Astronomy

Neutral atoms facility for space sensors characterization and BepiColombo/ELENA development instrument's progresses.

NASA Astrophysics Data System (ADS)

de Angelis, E.; di Lellis, A. M.; Orsini, S.; Zanza, V.; Maggi, M.; Vertolli, N.; D'Amicis, R.; Tilia, B.; Sibio, A.

2003-04-01

An Energetic Neutral Atoms facility to test and calibrate Neutral Atoms Analyzers has been developed in the Scientific Technical Unit of Fusion at the ENEA Research Center in Frascati (Rome-Italy). In the last years a collaboration with IFSI (Interplanetary Space and Physics Institute, CNR-Rome-Italy) has allowed to use this facility for space sensors and for characterization of crucial instruments elements. The ENA beam is realized with an ion source and a neutralization cell, and allows to test any instrument in the energy range 300eV-110keV with the available masses of Hydrogen, Deuterium or Helium. At the moment, the critical elements of ELENA (Emitted Low Energy Neutral Atoms) instrument proposed for BepiColombo ESA cornerstone mission to Mercury is under development testing. The facility, its potentiality and the instrument characterization progresses are presented.

Quantum field-theoretical description of neutrino and neutral kaon oscillations

NASA Astrophysics Data System (ADS)

Volobuev, Igor P.

2018-05-01

It is shown that the neutrino and neutral kaon oscillation processes can be consistently described in quantum field theory using only plane waves of the mass eigenstates of neutrinos and neutral kaons. To this end, the standard perturbative S-matrix formalism is modified so that it can be used for calculating the amplitudes of the processes passing at finite distances and finite time intervals. The distance-dependent and time-dependent parts of the amplitudes of the neutrino and neutral kaon oscillation processes are calculated and the results turn out to be in accordance with those of the standard quantum mechanical description of these processes based on the notion of neutrino flavor states and neutral kaon states with definite strangeness. However, the physical picture of the phenomena changes radically: now, there are no oscillations of flavor or definite strangeness states, but, instead of it, there is interference of amplitudes due to different virtual mass eigenstates.

Warm neutral halos around molecular clouds. VI - Physical and chemical modeling

NASA Technical Reports Server (NTRS)

Andersson, B.-G.; Wannier, P. G.

1993-01-01

A combined physical and chemical modeling of the halos around molecular clouds is presented, with special emphasis on the H-to-H2 transition. On the basis of H I 21 cm observations, it is shown that the halos are extended. A physical model is employed in conjunction with a chemistry code to provide a self-consistent description of the gas. The radiative transfer code provides a check with H I, CO, and OH observations. It is concluded that the warm neutral halos are not gravitationally bound to the underlying molecular clouds and are isobaric. It is inferred from the observed extent of the H I envelopes and the large observed abundance of OH in them that the generally accepted rate for H2 information on grains is too large by a factor of two to three.

High Power Helicon Plasma Source for Plasma Processing

NASA Astrophysics Data System (ADS)

Prager, James; Ziemba, Timothy; Miller, Kenneth E.

2015-09-01

Eagle Harbor Technologies (EHT), Inc. is developing a high power helicon plasma source. The high power nature and pulsed neutral gas make this source unique compared to traditional helicon source. These properties produce a plasma flow along the magnetic field lines, and therefore allow the source to be decoupled from the reaction chamber. Neutral gas can be injected downstream, which allows for precision control of the ion-neutral ratio at the surface of the sample. Although operated at high power, the source has demonstrated very low impurity production. This source has applications to nanoparticle productions, surface modification, and ionized physical vapor deposition.

Accelerator and Fusion Research Division. Annual report, October 1978-September 1979

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1980-03-01

Topics covered include: Super HILAC and Bevalac operations; high intensity uranium beams line item; advanced high charge state ion source; 184-inch synchrocyclotron; VENUS project; positron-electron project; high field superconducting accelerator magnets; beam cooling; accelerator theory; induction linac drivers; RF linacs and storage rings; theory; neutral beam systems development; experimental atomic physics; neutral beam plasma research; plasma theory; and the Tormac project. (GHT)

Measurement and analysis of electron-neutral collision frequency in the calibrated cutoff probe

DOE Office of Scientific and Technical Information (OSTI.GOV)

You, K. H.; Seo, B. H.; Kim, J. H.

2016-03-15

As collisions between electrons and neutral particles constitute one of the most representative physical phenomena in weakly ionized plasma, the electron-neutral (e-n) collision frequency is a very important plasma parameter as regards understanding the physics of this material. In this paper, we measured the e-n collision frequency in the plasma using a calibrated cutoff-probe. A highly accurate reactance spectrum of the plasma/cutoff-probe system, which is expected based on previous cutoff-probe circuit simulations [Kim et al., Appl. Phys. Lett. 99, 131502 (2011)], is obtained using the calibrated cutoff-probe method, and the e-n collision frequency is calculated based on the cutoff-probe circuitmore » model together with the high-frequency conductance model. The measured e-n collision frequency (by the calibrated cutoff-probe method) is compared and analyzed with that obtained using a Langmuir probe, with the latter being calculated from the measured electron-energy distribution functions, in wide range of gas pressure.« less

Effective Teaching in Physical Education: Slovenian Perspective

ERIC Educational Resources Information Center

Pišot, Rado; Plevnik, Matej; Štemberger, Vesna

2014-01-01

Regular quality physical education (PE) contributes to the harmonized biopsychosocial development of a young person--to relaxation, neutralization of negative effects of sedentary hours, and other unhealthy habits/behaviors. The evaluation approach to PE effectiveness provides important information to PE teachers and also to students. However,…

A weight-neutral versus weight-loss approach for health promotion in women with high BMI: A randomized-controlled trial.

PubMed

Mensinger, Janell L; Calogero, Rachel M; Stranges, Saverio; Tylka, Tracy L

2016-10-01

Weight loss is the primary recommendation for health improvement in individuals with high body mass index (BMI) despite limited evidence of long-term success. Alternatives to weight-loss approaches (such as Health At Every Size - a weight-neutral approach) have been met with their own concerns and require further empirical testing. This study compared the effectiveness of a weight-neutral versus a weight-loss program for health promotion. Eighty women, aged 30-45 years, with high body mass index (BMI ≥ 30 kg/m(2)) were randomized to 6 months of facilitator-guided weekly group meetings using structured manuals that emphasized either a weight-loss or weight-neutral approach to health. Health measurements occurred at baseline, post-intervention, and 24-months post-randomization. Measurements included blood pressure, lipid panels, blood glucose, BMI, weight, waist circumference, hip circumference, distress, self-esteem, quality of life, dietary risk, fruit and vegetable intake, intuitive eating, and physical activity. Intention-to-treat analyses were performed using linear mixed-effects models to examine group-by-time interaction effects and between and within-group differences. Group-by-time interactions were found for LDL cholesterol, intuitive eating, BMI, weight, and dietary risk. At post-intervention, the weight-neutral program had larger reductions in LDL cholesterol and greater improvements in intuitive eating; the weight-loss program had larger reductions in BMI, weight, and larger (albeit temporary) decreases in dietary risk. Significant positive changes were observed overall between baseline and 24-month follow-up for waist-to-hip ratio, total cholesterol, physical activity, fruit and vegetable intake, self-esteem, and quality of life. These findings highlight that numerous health benefits, even in the absence of weight loss, are achievable and sustainable in the long term using a weight-neutral approach. The trial positions weight-neutral programs as a viable health promotion alternative to weight-loss programs for women of high weight. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reduced model (SOLT) simulations of neutral-plasma interaction

NASA Astrophysics Data System (ADS)

Russell, David; Myra, James

2017-10-01

The 2D scrape-off-layer turbulence (SOLT) code has been enhanced by the addition of kinetic-neutral physics. Plasma-neutral interactions include charge exchange (CX) and ionization (IZ). Under the assumption that the CX and IZ collision rates are independent of the ion-neutral relative velocity, a 1D (radial: x) Boltzmann equation has been derived for the evolution of the (vy,vz) -averaged neutral distribution function (G), and that evolution has been added to SOLT. The CX and IZ rates are determined by the poloidally (y) averaged plasma density and temperatures, and G = G(x,vx,t). Results from 1D simulations that use diffusion as a proxy for turbulent transport are presented to illustrate the capability, including the approach to a steady state driven by sustained neutral injection in the far-SOL and source-driven heating in the core. Neutral density and energy profiles are obtained for the resulting self-consistent equilibrium plasma profiles. The effect of neutral drag on poloidal ExB mean flow and shearing rate is illustrated. Progress on 2D turbulence (blob) simulations is reported. Work supported by the U.S. Department of Energy Office of Science, Office of Fusion Energy Sciences, under Award Number DE-FG02-97ER54392.

The role of plasma/neutral source and loss processes in shaping the giant planet magnetospheres

NASA Astrophysics Data System (ADS)

Delamere, P. A.

2014-12-01

The giant planet magnetospheres are filled with neutral and ionized gases originating from satellites orbiting deep within the magnetosphere. The complex chemical and physical pathways for the flow of mass and energy in this partially ionized plasma environment is critical for understanding magnetospheric dynamics. The flow of mass at Jupiter and Saturn begins, primarily, with neutral gases emanating from Io (~1000 kg/s) and Enceladus (~200 kg/s). In addition to ionization losses, the neutral gases are absorbed by the planet, its rings, or escape at high speeds from the magnetosphere via charge exchange reactions. The net result is a centrifugally confined torus of plasma that is transported radially outward, distorting the magnetic field into a magnetodisc configuration. Ultimately the plasma is lost to the solar wind. A critical parameter for shaping the magnetodisc and determining its dynamics is the radial plasma mass transport rate (~500 kg/s and ~50 kg/s for Jupiter and Saturn respectively). Given the plasma transport rates, several simple properties of the giant magnetodiscs can be estimated including the physical scale of the magnetosphere, the magnetic flux transport, and the magnitude of azimuthal magnetic field bendback. We will discuss transport-related magnetic flux conservation and the mystery of plasma heating—two critical issues for shaping the giant planet magnetospheres.

Peer reactions to early childhood aggression in a preschool setting: Defenders, encouragers, or neutral bystander.

PubMed

Rose, Chad A; Richman, David M; Fettig, Katharine; Hayner, Annamarie; Slavin, Carly; Preast, June L

2016-08-01

The purpose of the current study was to determine if peer reactions to aggression among preschool youth were consistent with those conceptualized in the adolescent bullying literature as defenders, encouragers, and neutral bystanders. Direct observations were used to document patterns for types of peer-directed aggression in early childhood settings to ascertain interaction differences between individuals involved within the bullying dynamic. Observations of 50 students in preschool were conducted over 5.5 months. Event recording procedures were used to document aggressive behaviors and reactions from peers and teachers. Results indicated that the majority of aggression was physical. Additionally, peer reactions, as described in the bullying literature for school-aged youth, occurred very infrequently. Peer aggression tended to be more physical, suggesting that early childhood educators should attend to these physical interactions, and cultivate a classroom community that emphasizes social supports and appropriate interactions.

The role of top in heavy flavor physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hewett, J.L.

1997-01-01

The implications of the massive top quark on heavy flavor transitions are explored. We review the generation of quark masses and mixings and the determination techniques, and present the status of the elements of the weak mixing matrix. Purely leptonic decays of heavy mesons are briefly summarized. We present a general introduction to flavor changing neutral currents and an extensive summary of radiative and other rare decay modes. The physics of neutral meson mixing is reviewed and applied to each meson system. We describe the phenomenology of CP violation and how it may be measured in meson decays. Standard Modelmore » predictions are given in each case and the effects of physics beyond the Standard Model are also discussed. Throughout, we contrast these transitions in the K and B meson systems to those in the D meson and top-quark sectors.« less

A Taxonomy: Campus Physical Artifacts as Communicators of Campus Multiculturalism.

ERIC Educational Resources Information Center

Banning, James H.; Bartels, Sharon

1997-01-01

Presents a conceptual framework to assist campus personnel who are concerned about how physical artifacts on campus communicate institutional values associated with multiculturalism. Describes the four dimensions of the taxonomy and their usefulness in evaluating campus environments in terms of messages that promote, neutralize, or discourage the…

Spin and precision electroweak physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marciano, W.J.

1994-12-01

A perspective on fundamental parameters and precision tests of the Standard Model is given. Weak neutral current reactions are discussed with emphasis on those processes involving (polarized) electrons. The role of electroweak radiative corrections in determining the top quark mass and probing for {open_quotes}new physics{close_quotes} is described.

Physically adjusted NDF (paNDF) system for lactating dairy cow rations. I: Deriving equations that identify factors that influence effectiveness of fiber

USDA-ARS?s Scientific Manuscript database

Physically effective neutral detergent fiber (peNDF) is defined as the fraction of NDF that stimulates chewing activity and contributes to the floating mat of large particles in the rumen. The objective of this work was to re-evaluate the concept of peNDF by quantitatively relating physical and chem...

Concepts for the magnetic design of the MITICA neutral beam test facility ion accelerator.

PubMed

Chitarin, G; Agostinetti, P; Marconato, N; Marcuzzi, D; Sartori, E; Serianni, G; Sonato, P

2012-02-01

The megavolt ITER injector concept advancement neutral injector test facility will be constituted by a RF-driven negative ion source and by an electrostatic Accelerator, designed to produce a negative Ion with a specific energy up to 1 MeV. The beam is then neutralized in order to obtain a focused 17 MW neutral beam. The magnetic configuration inside the accelerator is of crucial importance for the achievement of a good beam efficiency, with the early deflection of the co-extracted and stripped electrons, and also of the required beam optic quality, with the correction of undesired ion beamlet deflections. Several alternative magnetic design concepts have been considered, comparing in detail the magnetic and beam optics simulation results, evidencing the advantages and drawbacks of each solution both from the physics and engineering point of view.

The Neutral Pentaquark

NASA Astrophysics Data System (ADS)

Moon, Russell; Calvo, Fabian; Vasiliev, Victor

2006-04-01

Using the principles of the Vortex Theory, it was discovered that when the gamma ray strikes a nucleon, the positively charged pentaquark [and the K^- meson] had to be created by the collision with neutron. This discovery further reveals that if the gamma ray strikes a proton it can create a Neutral Pentaquark [and a D^+ meson]. The neutral pentaquark will consist of an up, up, down, down, and an anti-charm quark, while the D^+ meson will consist of a charm and an anti-down quark. The neutral pentaquark will later decay into a neutron and D^0 meson. Because the vortex theory also reveals that the strong force couples a proton to a neutron, the neutron that was coupled to the proton in the nucleus will also be found amid the debris particles. 1. R. G. Moon, The Vortex Theory, The Beginning. Gordons Publications of Fort Lauderdale Fla., 2003, 184 pp. 2. R. G. Moon, The Vortex Theory Explains the Quark Theory. Gordons Publications of Fort Lauderdale Fla., 2005, 205 pp. 3. R.G. Moon, V.V. Vasiliev, The bases of the vortex theory, Book of abstracts The 53 International Meeting on Nuclear Spectroscopy and Nuclear structure, NUCLEUS-2003, October 7-10, 2003, Moscow, St.-Petersburg, Russia, 2003, p.251 4. R.G. Moon, V.V. Vasiliev, The Vortex Theory and Some Interaction in Nuclear Physics, Book of abstracts The 54 International Meeting on Nuclear Spectroscopy and Nuclear Structure, NUCLEUS-2004, June 22-25, 2004, Belgorod, Russia, 2004, p.259 5. R.G. Moon, V.V. Vasiliev. Explanation of the Conservation of Lepton Number, Book of abstracts LV National Conference on Nuclear Physics, Frontiers in the Physics of Nucleus, June 28-July 1, 2005, Saint-Petersburg, Russia, 2005, p. 347

Additional application of the NASCAP code. Volume 2: SEPS, ion thruster neutralization and electrostatic antenna model

NASA Technical Reports Server (NTRS)

Katz, I.; Cassidy, J. J.; Mandell, M. J.; Parks, D. E.; Schnuelle, G. W.; Stannard, P. R.; Steen, P. G.

1981-01-01

The interactions of spacecraft systems with the surrounding plasma environment were studied analytically for three cases of current interest: calculating the impact of spacecraft generated plasmas on the main power system of a baseline solar electric propulsion stage (SEPS), modeling the physics of the neutralization of an ion thruster beam by a plasma bridge, and examining the physical and electrical effects of orbital ambient plasmas on the operation of an electrostatically controlled membrane mirror. In order to perform these studies, the NASA charging analyzer program (NASCAP) was used as well as several other computer models and analytical estimates. The main result of the SEPS study was to show how charge exchange ion expansion can create a conducting channel between the thrusters and the solar arrays. A fluid-like model was able to predict plasma potentials and temperatures measured near the main beam of an ion thruster and in the vicinity of a hollow cathode neutralizer. Power losses due to plasma currents were shown to be substantial for several proposed electrostatic antenna designs.

Physical Activity and Executive Control: Implications for Increased Cognitive Health during Older Adulthood

ERIC Educational Resources Information Center

Hillman, Charles H.; Belopolsky, Artem V.; Snook, Erin M.; Kramer, Arthur F.; McAuley, Edward

2004-01-01

Electrocortical and behavioral responses of low, moderate, and high physically active older adults where compared with a younger control group on neutral and incompatible conditions of a flankers task. Compared to younger adults, high and moderate active older adults exhibited increased event-related potentials component P3 amplitude for the…

Development of SSUBPIC code for modeling the neutral gas depletion effect in helicon discharges

NASA Astrophysics Data System (ADS)

Kollasch, Jeffrey; Sovenic, Carl; Schmitz, Oliver

2017-10-01

The SSUBPIC (steady-state unstructured-boundary particle-in-cell) code is being developed to model helicon plasma devices. The envisioned modeling framework incorporates (1) a kinetic neutral particle model, (2) a kinetic ion model, (3) a fluid electron model, and (4) an RF power deposition model. The models are loosely coupled and iterated until convergence to steady-state. Of the four required solvers, the kinetic ion and neutral particle simulation can now be done within the SSUBPIC code. Recent SSUBPIC modifications include implementation and testing of a Coulomb collision model (Lemons et al., JCP, 228(5), pp. 1391-1403) allowing efficient coupling of kineticly-treated ions to fluid electrons, and implementation of a neutral particle tracking mode with charge-exchange and electron impact ionization physics. These new simulation capabilities are demonstrated working independently and coupled to ``dummy'' profiles for RF power deposition to converge on steady-state plasma and neutral profiles. The geometry and conditions considered are similar to those of the MARIA experiment at UW-Madison. Initial results qualitatively show the expected neutral gas depletion effect in which neutrals in the plasma core are not replenished at a sufficient rate to sustain a higher plasma density. This work is funded by the NSF CAREER award PHY-1455210 and NSF Grant PHY-1206421.

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

NASA Astrophysics Data System (ADS)

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).

Regular threshold-energy increase with charge for neutral-particle emission in collisions of electrons with oligonucleotide anions.

PubMed

Tanabe, T; Noda, K; Saito, M; Starikov, E B; Tateno, M

2004-07-23

Electron-DNA anion collisions were studied using an electrostatic storage ring with a merging electron-beam technique. The rate of neutral particles emitted in collisions started to increase from definite threshold energies, which increased regularly with ion charges in steps of about 10 eV. These threshold energies were almost independent of the length and sequence of DNA, but depended strongly on the ion charges. Neutral particles came from breaks of DNAs, rather than electron detachment. The step of the threshold energy increase approximately agreed with the plasmon excitation energy. It is deduced that plasmon excitation is closely related to the reaction mechanism. Copyright 2004 The American Physical Society

Negative Charge Neutralization in the Loops and Turns of Outer Membrane Phospholipase A Impacts Folding Hysteresis at Neutral pH.

PubMed

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.

Measurement of argon neutral velocity distribution functions near an absorbing boundary in a plasma

NASA Astrophysics Data System (ADS)

Short, Zachary; Thompson, Derek; Good, Timothy; Scime, Earl

2016-10-01

Neutral particle distributions are critical to the study of plasma boundary interactions, where ion-neutral collisions, e.g. via charge exchange, may modify energetic particle populations impacting the boundary surface. Neutral particle behavior at absorbing boundaries thus underlies a number of important plasma physics issues, such as wall loading in fusion devices and anomalous erosion in Hall thruster channels. Neutral velocity distribution functions (NVDFs) are measured using laser-induced fluorescence (LIF). Our LIF scheme excites the 1s4 non-metastable state of neutral argon with 667.913 nm photons. The subsequent decay emission at 750.590 nm is recorded synchronously with injection laser frequency. Measurements are performed near a grounded boundary immersed in a cylindrical helicon plasma, with the boundary plate oriented at an oblique angle to the magnetic field. NVDFs are recorded in multiple velocity dimensions and in a three-dimensional volume, enabling point-to-point comparisons with NVDF predictions from particle-in-cell models as well as comparisons with ion velocity distribution function measurements obtained in the same regions through Ar-II LIF. This work is supported by US National Science Foundation Grant Number PHYS-1360278.

Understanding self-assembly of charged-neutral block copolymer (BCP) and surfactant complexes using molecular dynamics (MD) simulation

NASA Astrophysics Data System (ADS)

Goswami, Monojoy; Sumpter, Bobby; Kilbey, Michael

Here we report the formation of phase separated BCP-surfactant complexes resulting from the electrostatic self-assembly of charge-neutral block copolymers with oppositely charged surfactants. Complexation behaviors of oppositely charged polyelectrolytes has gained considerable attention in the field of soft condensed matter physics due to their potential application as functional nanomaterials for batteries, wastewater treatment and drug delivery systems. Numerous experiments have examined the self-assembled structures resulting from complexation of charge-neutral BCP and surfactants, however, there is a lack of comprehensive understanding at the fundamental level. To help bridge this gap, we use, MD simulations to study self-assembly and dynamics of the BCP-surfactant complex at the molecular level. Our results show an overcharging effect in BCPs with hydrophobic neutral blocks and a formation of core-shell colloidal structure. Hydrophilic neutral blocks, on the other hand, show stable, hairy colloidal structures with neutral blocks forming a loosely-bound, fuzzy outer layer. Our results qualitatively agree with previous SANS and SAXS experiments. This work was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Materials Science and Engineering Division.

Neutral source and particle balance in the HSX edge

NASA Astrophysics Data System (ADS)

Stephey, Laurie; Kumar, Santhosh; Bader, Aaron; Akerson, Adrian; Schmitz, Oliver; Anderson, David; A, Simon; Talmadge, Joseph; Hegna, Chris

2015-11-01

The ability to control the neutral particle and impurity source in fusion devices is critical to obtaining high purity, high confinement plasmas. The neutral particle source defines the edge density gradients and plasma flows. To understand the relationship between the neutral particle source, plasma density gradients and plasma edge and core transport in HSX, a single reservoir particle balance is being used to provide a complete particle inventory. Detailed spectroscopic measurements of hydrogen and helium emission have yielded neutral and plasma profiles and ionization length estimations. The plasma puff source rate has been directly measured. To determine the recycling source rate, two specially designed limiters will be inserted to intercept 99% of the field lines, resulting in a well-defined LCFS and plasma interaction zone. Single limiter insertion resulted in a 50% reduction in global line emission, implying a reduction in wall recycling. Future camera and probe measurements will provide a recycling source rate. HSX neutral physics is also being investigated using EMC3-EIRENE. All results are discussed along with complementary plans for the Wendelstein 7-X startup phase. This work supported by US DOE Grant DE-FG02-93ER54222 and DE-SC0006103.

Dirac R -matrix calculations for the electron-impact excitation of neutral tungsten providing noninvasive diagnostics for magnetic confinement fusion

NASA Astrophysics Data System (ADS)

Smyth, R. T.; Ballance, C. P.; Ramsbottom, C. A.; Johnson, C. A.; Ennis, D. A.; Loch, S. D.

2018-05-01

Neutral tungsten is the primary candidate as a wall material in the divertor region of the International Thermonuclear Experimental Reactor (ITER). The efficient operation of ITER depends heavily on precise atomic physics calculations for the determination of reliable erosion diagnostics, helping to characterize the influx of tungsten impurities into the core plasma. The following paper presents detailed calculations of the atomic structure of neutral tungsten using the multiconfigurational Dirac-Fock method, drawing comparisons with experimental measurements where available, and includes a critical assessment of existing atomic structure data. We investigate the electron-impact excitation of neutral tungsten using the Dirac R -matrix method, and by employing collisional-radiative models, we benchmark our results with recent Compact Toroidal Hybrid measurements. The resulting comparisons highlight alternative diagnostic lines to the widely used 400.88-nm line.

K S 0 - K L 0 asymmetries and CP violation in charmed baryon decays into neutral kaons

NASA Astrophysics Data System (ADS)

Wang, Di; Guo, Peng-Fei; Long, Wen-Hui; Yu, Fu-Sheng

2018-03-01

We study the K S 0 - K L 0 asymmetries and CP violations in charm-baryon decays with neutral kaons in the final state. The K S 0 - K L 0 asymmetry can be used to search for two-body doubly Cabibbo-suppressed amplitudes of charm-baryon decays, with the one in Λ c + → pK S, L 0 as a promising observable. Besides, it is studied for a new CP-violation effect in these processes, induced by the interference between the Cabibbo-favored and doubly Cabibbo-suppressed amplitudes with the neutral kaon mixing. Once the new CP-violation effect is determined by experiments, the direct CP asymmetry in neutral kaon modes can then be extracted and used to search for new physics. The numerical results based on SU(3) symmetry will be tested by the experiments in the future.

Theoretical study of the ionospheric plasma cave in the equatorial ionization anomaly region

NASA Astrophysics Data System (ADS)

Chen, Yu-Tsung; Lin, C. H.; Chen, C. H.; Liu, J. Y.; Huba, J. D.; Chang, L. C.; Liu, H.-L.; Lin, J. T.; Rajesh, P. K.

2014-12-01

This paper investigates the physical mechanism of an unusual equatorial electron density structure, plasma cave, located underneath the equatorial ionization anomaly by using theoretical simulations. The simulation results provide important new understanding of the dynamics of the equatorial ionosphere. It has been suggested previously that unusual E>⇀×B>⇀ drifts might be responsible for the observed plasma cave structure, but model simulations in this paper suggest that the more likely cause is latitudinal meridional neutral wind variations. The neutral winds are featured by two divergent wind regions at off-equator latitudes and a convergent wind region around the magnetic equator, resulting in plasma divergences and convergence, respectively, to form the plasma caves structure. The tidal-decomposition analysis further suggests that the cave related meridional neutral winds and the intensity of plasma cave are highly associated with the migrating terdiurnal tidal component of the neutral winds.

A Statistical Model of the Magnetotail Neutral Sheet

NASA Astrophysics Data System (ADS)

Xiao, Sudong; Zhang, Tielong; Baumjohann, Wolfgang; Nakamura, Rumi; Ge, Yasong; Du, Aimin; Wang, Guoqiang; Lu, Quanming

2015-04-01

The neutral sheet of the magnetotail is characterized by weak magnetic field, strong cross tail current, and a reversal of the magnetic field direction across it. The dynamics of the earth's magnetosphere is greatly influenced by physical processes that occur near the neutral sheet. However, the exact position of the neutral sheet is variable in time. It is therefore essential to have a reliable estimate of the average position of the neutral sheet. Magnetic field data from ten years of Cluster, nineteen years of Geotail, four years of TC 1, and seven years of THEMIS observations have been incorporated to obtain a model of the magnetotail neutral sheet. All data in aberrated GSM (Geocentric Solar Magnetospheric) coordinate system are normalized to the same solar wind pressure condition. The shape and position of the neutral sheet, illustrated directly by the separator of positive and negative Bx on the YZ cross sections, are fitted with a displaced ellipse model. It is consistent with previous studies that the neutral sheet becomes curvier in the YZ cross section when the dipole tilt increases, yet our model shows the curviest neutral sheet compared with previous models. The new model reveals a hinging distance very close to 10 RE at a reference solar wind dynamic pressure of 2 nPa. We find that the earth dipole tilt angle not only affects the neutral sheet configuration in the YZ cross section but also in the XZ cross section. The neutral sheet becomes more tilting in the XZ cross section when the dipole tilt increases. The effect of an interplanetary magnetic field (IMF) penetration is studied, and an IMF By-related twisting of about 3° is found. Anticlockwise twisting of the neutral sheet is observed, looking along the downtail direction, for a positive IMF By, and clockwise twisting of the neutral sheet for a negative IMF By.

Physics design of the injector source for ITER neutral beam injector (invited).

PubMed

Antoni, V; Agostinetti, P; Aprile, D; Cavenago, M; Chitarin, G; Fonnesu, N; Marconato, N; Pilan, N; Sartori, E; Serianni, G; Veltri, P

2014-02-01

Two Neutral Beam Injectors (NBI) are foreseen to provide a substantial fraction of the heating power necessary to ignite thermonuclear fusion reactions in ITER. The development of the NBI system at unprecedented parameters (40 A of negative ion current accelerated up to 1 MV) requires the realization of a full scale prototype, to be tested and optimized at the Test Facility under construction in Padova (Italy). The beam source is the key component of the system and the design of the multi-grid accelerator is the goal of a multi-national collaborative effort. In particular, beam steering is a challenging aspect, being a tradeoff between requirements of the optics and real grids with finite thickness and thermo-mechanical constraints due to the cooling needs and the presence of permanent magnets. In the paper, a review of the accelerator physics and an overview of the whole R&D physics program aimed to the development of the injector source are presented.

Predictions for neutral K and B meson physics

NASA Astrophysics Data System (ADS)

Dimopoulos, Savas; Hall, Lawrence J.; Raby, Stuart

1992-12-01

Using supersymmetric grand unified theories, we have recently invented a framework which allows the prediction of three quark masses, two of the parameters of the Kobayashi-Maskawa matrix, and tanβ, the ratio of the two electroweak vacuum expectation values. These predictions are used to calculate ɛ and ɛ' in the kaon system, the mass mixing in the B0d and B0s systems, and the size of CP asymmetries in the decays of neutral B mesons to explicit final states of given CP.

Mars aerobrake assembly simulation

NASA Technical Reports Server (NTRS)

Filatovs, G. J.; Lee, Gordon K. F.; Garvey, John

1992-01-01

On-orbit assembly operation simulations in neutral buoyancy conditions are presently undertaken by a partial/full-scale Mars mission aerobrake mockup, whose design, conducted in the framework of an engineering senior students' design project, involved several levels of constraints for critical physical and operational features. Allowances had to be made for the auxiliary constraints introduced by underwater testing, as well as the subsegmenting required for overland shipment to the neutral-buoyancy testing facility. This mockup aerobrake's fidelity is determined by the numerous, competing design objectives.

Plasma physics analysis of SERT-2 operation

NASA Technical Reports Server (NTRS)

Kaufman, H. R.

1980-01-01

An analysis of the major plasma processes involved in the SERT 2 spacecraft experiments was conducted to aid in the interpretation of recent data. A plume penetration model was developed for neutralization electron conduction to the ion beam and showed qualitative agreement with flight data. In the SERT 2 configuration conduction of neutralization electrons between thrusters was experimentally demonstrated in space. The analysis of this configuration suggests that the relative orientation of the two magnetic fields was an important factor in the observed results. Specifically, the opposed field orientation appeared to provide a high conductivity channel between thrusters and a barrier to the ambient low energy electrons in space. The SERT 2 neutralizer currents with negative neutralizer biases were up to about twice the theoretical prediction for electron collection by the ground screen. An explanation for the higher experimental values was a possible conductive path from the neutralizer plume to a nearby part of the ground screen. Plasma probe measurements of SERT 2 gave the clearest indication of plasma electron temperature, with normal operation being near 5 eV and discharge only operation near 2 eV.

Strange Particle Reconstruction by the Missing Mass Method

NASA Astrophysics Data System (ADS)

Kisel, Pavel; Kisel, Ivan; Senger, Peter; Vassiliev, Iouri; Zyzak, Maksym

2018-02-01

The main goal of modern heavy-ion experiments is a comprehensive study of the QCD phase diagram, in a region of Quark-Gluon Plasma (QGP) and possible phase transition to QGP phase. Strange particles produced in the collision are sensitive probes of the created media. Reconstruction of Σ particles together with other strange particles completes the picture of strangeness production. Σ+ and Σ- have all decay modes with at least one neutral daughter, which can not be registered by the CBM detector. For their identification the missing mass method is proposed: a) tracks of the mother (Σ-) and the charged daughter (π-) particles are reconstructed in the tracking system; b) the neutral daughter particle (n) is reconstructed from these tracks; c) a mass constraint is set on the reconstructed neutral daughter; d) the mother particle is constructed of the charged and reconstructed neutral daughter particles and the mass spectrum is obtained, by which the particle can be identified. The method can be applied for other strange particles too. In total 18 particle decays with neutral daughter are now included into physics analysis.

Association with emotional information alters subsequent processing of neutral faces

PubMed Central

Riggs, Lily; Fujioka, Takako; Chan, Jessica; McQuiggan, Douglas A.; Anderson, Adam K.; Ryan, Jennifer D.

2014-01-01

The processing of emotional as compared to neutral information is associated with different patterns in eye movement and neural activity. However, the ‘emotionality’ of a stimulus can be conveyed not only by its physical properties, but also by the information that is presented with it. There is very limited work examining the how emotional information may influence the immediate perceptual processing of otherwise neutral information. We examined how presenting an emotion label for a neutral face may influence subsequent processing by using eye movement monitoring (EMM) and magnetoencephalography (MEG) simultaneously. Participants viewed a series of faces with neutral expressions. Each face was followed by a unique negative or neutral sentence to describe that person, and then the same face was presented in isolation again. Viewing of faces paired with a negative sentence was associated with increased early viewing of the eye region and increased neural activity between 600 and 1200 ms in emotion processing regions such as the cingulate, medial prefrontal cortex, and amygdala, as well as posterior regions such as the precuneus and occipital cortex. Viewing of faces paired with a neutral sentence was associated with increased activity in the parahippocampal gyrus during the same time window. By monitoring behavior and neural activity within the same paradigm, these findings demonstrate that emotional information alters subsequent visual scanning and the neural systems that are presumably invoked to maintain a representation of the neutral information along with its emotional details. PMID:25566024

Development of a negative ion-based neutral beam injector in Novosibirsk.

PubMed

Ivanov, A A; Abdrashitov, G F; Anashin, V V; Belchenko, Yu I; Burdakov, A V; Davydenko, V I; Deichuli, P P; Dimov, G I; Dranichnikov, A N; Kapitonov, V A; Kolmogorov, V V; Kondakov, A A; Sanin, A L; Shikhovtsev, I V; Stupishin, N V; Sorokin, A V; Popov, S S; Tiunov, M A; Belov, V P; Gorbovsky, A I; Kobets, V V; Binderbauer, M; Putvinski, S; Smirnov, A; Sevier, L

2014-02-01

A 1000 keV, 5 MW, 1000 s neutral beam injector based on negative ions is being developed in the Budker Institute of Nuclear Physics, Novosibirsk in collaboration with Tri Alpha Energy, Inc. The innovative design of the injector features the spatially separated ion source and an electrostatic accelerator. Plasma or photon neutralizer and energy recuperation of the remaining ion species is employed in the injector to provide an overall energy efficiency of the system as high as 80%. A test stand for the beam acceleration is now under construction. A prototype of the negative ion beam source has been fabricated and installed at the test stand. The prototype ion source is designed to produce 120 keV, 1.5 A beam.

Polyelectrolytes tethered to a free surface

NASA Astrophysics Data System (ADS)

Dubreuil, F.; Guenoun, P.

Several attempts have been already carried out in order to tether charged chains by an end at a free fluctuating surface. We review here most of these attempts and focus on how close the physics of charged brushes can be investigated by such an approach. We first describe results about films of charged-neutral diblock copolymers spread at the surface of water. Results can be mostly rationalized in terms of charged brushes although additional structurations and fluctuations of the interface can be observed. The latter deformations are also observed when adsorbed layers of charged-neutral diblock copolymers are considered. At last, we examine how free suspended films of charged-neutral diblock copolymers can be viewed as two opposing charged brushes, both in terms of thickness and pressure.

Spontaneously Broken Neutral Symmetry in an Ecological System

NASA Astrophysics Data System (ADS)

Borile, C.; Muñoz, M. A.; Azaele, S.; Banavar, Jayanth R.; Maritan, A.

2012-07-01

Spontaneous symmetry breaking plays a fundamental role in many areas of condensed matter and particle physics. A fundamental problem in ecology is the elucidation of the mechanisms responsible for biodiversity and stability. Neutral theory, which makes the simplifying assumption that all individuals (such as trees in a tropical forest)—regardless of the species they belong to—have the same prospect of reproduction, death, etc., yields gross patterns that are in accord with empirical data. We explore the possibility of birth and death rates that depend on the population density of species, treating the dynamics in a species-symmetric manner. We demonstrate that dynamical evolution can lead to a stationary state characterized simultaneously by both biodiversity and spontaneously broken neutral symmetry.

Workshop on Physics with Neutral Kaon Beam at JLab (KL2016) Mini-Proceedings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strakovsky, Igor I.; Amaryan, Moskov; Chudakov, Eugene A.

2016-05-01

The KL2016 Workshop is following the Letter of Intent LoI12-15-001 "Physics Opportunities with Secondary KL beam at JLab" submitted to PAC43 with the main focus on the physics of excited hyperons produced by the Kaon beam on unpolarized and polarized targets with GlueX setup in Hall D. Such studies will broaden a physics program of hadron spectroscopy extending it to the strange sector. The Workshop was organized to get a feedback from the community to strengthen physics motivation of the LoI and prepare a full proposal.

The Development and Implementation of Career Information and Guidance Systems to Enhance Recruitment and Retention of ROTC Cadets for Army Careers

DTIC Science & Technology

1990-07-01

relations, variety, working conditions, cultural identity, physical prowess, and economic security. The measures of reliability were computed for the VS: 1...Prowess, Ability Utilization, and Physical Activity and the lowest scale scores on Cultural Identity, Social Relations, and Prestige. Those with neutral...and Cultural Identity and the lowest scale scores on Physical Prowess, Advancement, and Risk. Table 14 Highest and Lowest Rated Value Scale Dimensions

Collaborative Research: A Model of Partially Ionized Plasma Flows with Kinetic Treatment of Neutral Atoms and Nonthermal Ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pogorelov, Nikolai; Zhang, Ming; Borovikov, Sergey

Interactions of flows of partially ionized, magnetized plasma are frequently accompanied by the presence of both thermal and non-thermal (pickup) ion components. Such interactions cannot be modeled using traditional MHD equations and require more advanced approaches to treat them. If a nonthermal component of ions is formed due to charge exchange and collisions between the thermal (core) ions and neutrals, it experiences the action of magnetic field, its distribution function is isotropized, and it soon acquires the velocity of the ambient plasma without being thermodynamically equilibrated. This situation, e. g., takes place in the outer heliosphere - the part ofmore » interstellar space beyond the solar system whose properties are determined by the solar wind interaction with the local interstellar medium. This is also possible in laboratory, at million degrees and above, when plasma is conducting electricity far too well, which makes Ohmic heating ineffective. To attain the target temperatures one needs additional heating eventually playing a dominant role. Among such sources is a so-called neutral particle beam heating. This is a wide-spread technique (Joint European Torus and International Thermonuclear Experimental Reactor experiments) based on the injection of powerful beams of neutral atoms into ohmically preheated plasma. In this project we have investigated the energy and density separation between the thermal and nonthermal components in the solar wind and interstellar plasmas. A new model has been developed in which we solve the ideal MHD equations for mixture of all ions and the kinetic Boltzmann equation to describe the transport of neutral atoms. As a separate capability, we can treat the flow of neutral atoms in a multi-component fashion, where neutral atoms born in each thermodynamically distinct regions are governed by the Euler gas dynamic equations. We also describe the behavior of pickup ions either kinetically, using the Fokker–Planck equation, or as a separate fluid. Our numerical simulations have demonstrated that pickup ions play a major role in the interaction of the solar wind and (partially ionized) interstellar medium plasmas. Our teams have investigated the stability of the surface (the heliopause) that separates the solar wind from the local interstellar medium, the transport of galactic cosmic rays, the properties of the heliotail flow, and modifications to the bow wave in front of the heliopause due to charge exchange between the neutral H atoms born in the solar wind and interstellar ions. Modeling results have been validated against observational data, such as obtained by the Interstellar Boundary Explorer (IBEX), and made it possible to shed light on the structure of energetic neutral atom maps created by this spacecraft.. We have also demonstrated that charge-exchange modulated heliosphere is a source of anisotropy of the multi-TeV cosmic ray flux observed in a number of Earth-bound air shower experiments. Newly developed codes are implemented within a Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS), a publicly available code being developed by our team for over 12 years. MS-FLUKSS scales well up to 160,000 computing cores and has been ported on major supercomputers in the country. Efficient parallelization and data choreography in the continuum simulation modules are provided by Chombo, an adaptive mesh refinement framework managed by Phillip Colella’s team at LBNL. We have implemented in-house, hybrid (MPI+OpenMP) parallelization of the kinetic modules that solve the Boltzmann equation with a Monte Carlo method. Currently, the kinetic modules are being rewritten to take advantage of the modern CPU-GPU supercomputer architecture. The scope of the project allowed us to enhance plasma research and education in such broad, multidis- ciplinary field as physics of partially ionized plasma and its application to space physics and fusion science. Besides the impact on the modeling of complex physical systems, our approach to computational resource management for complex codes utilizing multiple algorithm technologies appears to be a major advance on current approaches. The development of sophisticated resource management will be essential for all future modeling efforts that incorporate a diversity of scales and physical processes. Our effort provided leadership in promoting computational science and plasma physics within the UAH and FIT campuses and, through the training of a broad spectrum of scientists and engineers, foster new technologies across the country.« less

Collaborative Research: A Model of Partially Ionized Plasma Flows with Kinetic Treatment of Neutral Atoms and Nonthermal Ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pogorelov, Nikolai; Zhang, Ming

Interactions of flows of partially ionized, magnetized plasma are frequently accompanied by the presence of both thermal and non-thermal (pickup) ion components. Such interactions cannot be modeled using traditional MHD equations and require more advanced approaches to treat them. If a nonthermal component of ions is formed due to charge exchange and collisions between the thermal (core) ions and neutrals, it experiences the action of magnetic field, its distribution function is isotropized, and it soon acquires the velocity of the ambient plasma without being thermodynamically equilibrated. This situation, e. g., takes place in the outer heliosphere –- the part ofmore » interstellar space beyond the solar system whose properties are determined by the solar wind interaction with the local interstellar medium. This is also possible in laboratory, at million degrees and above, when plasma is conducting electricity far too well, which makes Ohmic heating ineffective. To attain the target temperatures one needs additional heating eventually playing a dominant role. Among such sources is a so-called neutral particle beam heating. This is a wide-spread technique (Joint European Torus and International Thermonuclear Experimental Reactor experiments) based on the injection of powerful beams of neutral atoms into ohmically preheated plasma. In this project we have investigated the energy and density separation between the thermal and nonthermal components in the solar wind and interstellar plasmas. A new model has been developed in which we solve the ideal MHD equations for mixture of all ions and the kinetic Boltzmann equation to describe the transport of neutral atoms. As a separate capability, we can treat the flow of neutral atoms in a multi-component fashion, where neutral atoms born in each thermodynamically distinct region are governed by the Euler gas dynamic equations. We also describe the behavior of pickup ions either kinetically, using the Fokker--Planck equation, or as a separate fluid. Our numerical simulations have demonstrated that pickup ions play a major role in the interaction of the solar wind and (partially ionized) interstellar medium plasmas. Our teams have investigated the stability of the surface (the heliopause) that separates the solar wind from the local interstellar medium, the transport of galactic cosmic rays, the properties of the heliotail flow, and modifications to the bow wave in front of the heliopause due to charge exchange between the neutral H atoms born in the solar wind and interstellar ions. Modeling results have been validated against observational data, such as obtained by the Interstellar Boundary Explorer (IBEX), and made it possible to shed light on the structure of energetic neutral atom maps created by this spacecraft.. We have also demonstrated that charge-exchange modulated heliosphere is a source of anisotropy of the multi-TeV cosmic ray flux observed in a number of Earth-bound air shower experiments. Newly developed codes are implemented within a Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS), a publicly available code being developed by our team for over 12 years. MS-FLUKSS scales well up to 160,000 computing cores and has been ported on major supercomputers in the country. Efficient parallelization and data choreography in the continuum simulation modules are provided by Chombo, an adaptive mesh refinement framework managed by Phillip Colella's team at LBNL. We have implemented in-house, hybrid (MPI+OpenMP) parallelization of the kinetic modules that solve the Boltzmann equation with a Monte Carlo method. Currently, the kinetic modules are being rewritten to take advantage of the modern CPU-GPU supercomputer architecture. The scope of the project allowed us to enhance plasma research and education in such broad, multidisciplinary field as physics of partially ionized plasma and its application to space physics and fusion science. Besides the impact on the modeling of complex physical systems, our approach to computational resource management for complex codes utilizing multiple algorithm technologies appears to be a major advance on current approaches. The development of sophisticated resource management will be essential for all future modeling efforts that incorporate a diversity of scales and physical processes. Our effort provided leadership in promoting computational science and plasma physics within the UAH and FIT campuses and, through the training of a broad spectrum of scientists and engineers, fostering new technologies across the country.« less

40 CFR Appendix D to Part 300 - Appropriate Actions and Methods of Remedying Releases

Code of Federal Regulations, 2011 CFR

2011-07-01

... facultative lagoons. (C) Supported growth biological reactors. (D) Microbial biodegradation. (ii) Chemical...) Neutralization. (D) Equalization. (E) Chemical oxidation. (iii) Physical methods, including the following: (A...

Moderators of age effects on attention bias toward threat and its association with anxiety.

PubMed

Namaky, Nauder; Beltzer, Miranda L; Werntz, Alexandra J; Lambert, Ann E; Isaacowitz, Derek M; Teachman, Bethany A

2017-07-01

The current study used a research domain criteria (RDoC) approach to assess age differences in multiple indicators of attention bias and its ties to anxiety, examining stimulus domain and cognitive control as moderators of older adults' oft-cited positivity effect (bias towards positive and away from negative stimuli, when compared to younger adults). 38 Younger adults and 38 older adults were administered a battery of cognitive control and trait and state anxiety measures, and completed a dot-probe task to assess attention bias, during which reaction time and fixation duration (using eye-tracking) were recorded for negative and neutral social (a salient threat domain for younger adults) and physical (a salient threat domain for older adults) stimuli. Mixed-effects models demonstrated that older adults were faster to react to dot-probe trials when the probe appeared in the place of negative (vs. neutral) physical stimuli, but displayed no difference in reaction time for social stimuli. Also, older (vs. younger) adults with lower levels of cognitive control were less negatively biased in their visual fixation to social stimuli. A negative reaction time attention bias on the dot-probe task predicted greater trait anxiety among participants with low levels of cognitive control, with a more complex pattern predicting state anxiety. Older adults do attend to social and physical stimuli differently. When stimuli concern a social threat, older adults do not preferentially attend to either neutral or negative stimuli. However, when stimuli concern physical threat, older adults preferentially attend to negative stimuli. Threat biases are associated with anxiety at all ages for those with low cognitive control. Copyright © 2016. Published by Elsevier B.V.

Science Notes.

ERIC Educational Resources Information Center

School Science Review, 1985

1985-01-01

Presents 23 experiments, activities, field projects and computer programs in the biological and physical sciences. Instructional procedures, experimental designs, materials, and background information are suggested. Topics include fluid mechanics, electricity, crystals, arthropods, limpets, acid neutralization, and software evaluation. (ML)

The eXtra Small Analyzer for Neutrals (XSAN) instrument on-board of the Lunar-Glob lander

NASA Astrophysics Data System (ADS)

Wieser, Martin; Barabash, Stas

A large fraction of up to 20 precent of the solar wind impinging onto the lunar surface is reflected back to space as energetic neutral atoms. The SARA instrument on the Chandrayaan-1 mission provided a comprehensive coverage of the lunar surface of this interaction by mapping it from a 100 - 200 km orbit. The micro-physics of this reflection process is unexplored however. With the eXtra Small Analyzer for Neutrals instrument (XSAN) placed on the Lunar-Glob lander, we will directly investigate the production process of energetic neutral atoms from a vantage point of only meters from the surface for the first time. The XSAN design is based on the Solar Wind Monitor (SWIM) family of instruments originally flown on the Indian Chandrayaan-1 mission and with derivatives built e.g. for ESA's BepiColombo Mission to Mercury or for Phobos-Grunt. XSAN extends the functionality of this instrument family by adding a neutral atom to ion conversion surface in its entrance system. This will make it possible to measure detailed energy spectra and mass composition of the energetic neutral atoms originating from the lunar surface. We present an overview of the XSAN instrument and its science and report on latest developments.

Preface of the special issue: "Vertical coupling in the atmosphere-ionosphere system: Recent progress"

NASA Astrophysics Data System (ADS)

2018-06-01

This special issue of the Journal of Atmospheric and Solar-Terrestrial Physics comprises papers dealing with investigation of the coupling phenomena in the neutral Atmosphere-Ionosphere System of the Earth. The core of the special issue is formed by the recent results presented during the 6th IAGA/ICMA/SCOSTEP Workshop on the Vertical Coupling in the Neutral Atmosphere-Ionosphere System held in Taipei, Taiwan, July 2016. Workshops are organized with a substantial support of the scientific international bodies, such as the International Association of Geomagnetism and Aeronomy (IAGA), International Commission for the Middle Atmosphere (ICMA) and Committee on Solar-Terrestrial Physics (SCOSTEP). The special issue includes also recent results of other members of the aeronomic research community. Hence it represents the state-of-art knowledge in the associated research fields.

Energetic neutral atoms measured by the interstellar boundary explorer (IBEX): evidence for multiple heliosheath populations

DOE PAGES

Desai, M. I.; Allegrini, F. A.; Bzowski, M.; ...

2013-12-13

Energetic neutral atoms (ENAs) observed by the Interstellar Boundary Explorer (IBEX) provide powerful diagnostics about the origin of the progenitor ion populations and the physical mechanisms responsible for their production. In this paper, we extend the work of Desai et al. and Fuselier et al. and combine and compare ENA spectra from the first 3 yr of observations by the IBEX-Hi and -Lo ENA imagers along the lines-of-sight (LOSs) from the inner heliosphere through to the locations of Voyager 1 and 2 with results from an updated physics-based model of the three-dimensional heliosphere and its constituent ion populations. Our resultsmore » show that (1) IBEX ENA fluxes and spectra above ~0.7 keV measured along the LOSs of the Voyagers are consistent with several models in which the parent pickup ion (PUI) populations originate in the inner heliosheath, and (2) a significant fraction of lower energy ENAs between ~0.1-0.5 keV may originate from interstellar neutral gas charge-exchanging with a non-thermalized (hot) population of PUIs in the outer heliosheath beyond the heliopause. Here we discuss the implications of ENAs observed by IBEX originating from distinct parent populations as well as from two distinct locations in the heliospheric interface. In conclusion, these results indicate that ENA spectral measurements at various energies can be used to remotely probe distinct physical processes operating in vastly different regions of the distant heliosphere.« less

Energetic Neutral Atoms Measured by the Interstellar Boundary Explorer (IBEX): Evidence for Multiple Heliosheath Ion Populations

NASA Astrophysics Data System (ADS)

Desai, M. I.; Allegrini, F.; Bzowski, M.; Dayeh, M. A.; Funsten, H. O.; Fuselier, S.; Kubiak, M. A.; McComas, D. J.; Pogorelov, N. V.; Schwadron, N.; Sokol, J. M.; Zank, G. P.; Zirnstein, E. J.

2013-12-01

Energetic Neutral Atoms (ENAs) observed by the Interstellar Boundary Explorer (IBEX) provide powerful diagnostics about the origin of the progenitor ion populations and the physical mechanisms responsible for their production. In this paper, we extend the work of Desai et al. (2012) and Fuselier et al. (2012) and combine and compare ENA spectra from the first three years of observations by the IBEX-Hi and -Lo ENA imagers along the lines-of-sights (LOS) from the inner heliosphere through to the locations of Voyager 1 and 2 with results from an updated physics-based model of the 3D heliosphere and its constituent ion populations. Our results show that (1) IBEX ENA fluxes and spectra above ~0.7 keV measured along the LOS of the Voyagers are consistent with several models in which the parent pickup (PUI) populations originate in the inner heliosheath, and (2) a significant fraction of lower-energy ENAs between ~0.1-0.5 keV may originate from interstellar neutral gas charge-exchanging with a non-thermalized (hot) population of PUIs in the outer heliosheath beyond the heliopause. We discuss the implications of ENAs observed by IBEX originating from distinct parent populations as well as from two distinct locations in the heliospheric interface. These results indicate that ENA spectral measurements at various energies can be used to remotely probe distinct physical processes operating in vastly different regions of the distant heliosphere.

Energetic Neutral Atoms Measured by the Interstellar Boundary Explorer (IBEX): Evidence for Multiple Heliosheath Populations

NASA Astrophysics Data System (ADS)

Desai, M. I.; Allegrini, F. A.; Bzowski, M.; Dayeh, M. A.; Funsten, H.; Fuselier, S. A.; Heerikhuisen, J.; Kubiak, M. A.; McComas, D. J.; Pogorelov, N. V.; Schwadron, N. A.; Sokół, J. M.; Zank, G. P.; Zirnstein, E. J.

2014-01-01

Energetic neutral atoms (ENAs) observed by the Interstellar Boundary Explorer (IBEX) provide powerful diagnostics about the origin of the progenitor ion populations and the physical mechanisms responsible for their production. In this paper, we extend the work of Desai et al. and Fuselier et al. and combine and compare ENA spectra from the first 3 yr of observations by the IBEX-Hi and -Lo ENA imagers along the lines-of-sight (LOSs) from the inner heliosphere through to the locations of Voyager 1 and 2 with results from an updated physics-based model of the three-dimensional heliosphere and its constituent ion populations. Our results show that (1) IBEX ENA fluxes and spectra above ~0.7 keV measured along the LOSs of the Voyagers are consistent with several models in which the parent pickup ion (PUI) populations originate in the inner heliosheath, and (2) a significant fraction of lower energy ENAs between ~0.1-0.5 keV may originate from interstellar neutral gas charge-exchanging with a non-thermalized (hot) population of PUIs in the outer heliosheath beyond the heliopause. We discuss the implications of ENAs observed by IBEX originating from distinct parent populations as well as from two distinct locations in the heliospheric interface. These results indicate that ENA spectral measurements at various energies can be used to remotely probe distinct physical processes operating in vastly different regions of the distant heliosphere.

Efficient Means of Detecting Neutral Atoms in Space

NASA Astrophysics Data System (ADS)

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.

Laboratory Experiments Enabling Electron Beam use in Tenuous Space Plasmas

NASA Astrophysics Data System (ADS)

Miars, G.; Leon, O.; Gilchrist, B. E.; Delzanno, G. L.; Castello, F. L.; Borovsky, J.

2017-12-01

A mission concept is under development which involves firing a spacecraft-mounted electron beam from Earth's magnetosphere to connect distant magnetic field lines in real time. To prevent excessive spacecraft charging and consequent beam return, the spacecraft must be neutralized in the tenuous plasma environment of the magnetosphere. Particle-In-Cell (PIC) simulations suggest neutralization can be accomplished by emitting a neutral plasma with the electron beam. Interpretation of these simulations also led to an ion emission model in which ion current is emitted from a quasi-neutral plasma as defined by the space charge limit [1,2]. Experiments were performed at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL) to help validate the ion emission model. A hollow cathode plasma contactor was used as a representative spacecraft and charged with respect to the chamber walls to examine the effect of spacecraft charging on ion emission. Retarding Potential Analyzer (RPA) measurements were performed to understand ion flow velocity as this parameter relates directly to the expected space charge limit. Planar probe measurements were also made to identify where ion emission primarily occurred and to determine emission current density levels. Evidence of collisions within the plasma (particularly charge exchange collisions) and a simple model predicting emitted ion velocities are presented. While a detailed validation of the ion emission model and of the simulation tools used in [1,2] is ongoing, these measurements add to the physical understanding of ion emission as it may occur in the magnetosphere. 1. G.L. Delzanno, J.E. Borovsky, M.F. Thomsen, J.D. Moulton, and E.A. MacDonald, J. Geophys. Res. Space Physics 120, 3647, 2015. 2. G.L. Delzanno, J.E. Borovsky, M.F. Thomsen, and J.D. Moulton, J. Geophys. Res. Space Physics 120, 3588, 2015. ________________________________ * This work is supported by Los Alamos National Laboratory.

A Novel Treatment for Acid Mine Drainage Utilizing Reclaimed Limestone Residual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horace K. Moo-Young; Charles E. Ochola

2004-08-31

The viability of utilizing Reclaimed Limestone Residual (RLR) to remediate Acid Mine Drainage (AMD) was investigated. Physical and chemical characterization of RLR showed that it is composed of various minerals that contain significant quantities of limestone or calcium bearing compounds that can be exploited for acid neutralization. Acid Neutralization Potential (ANP) test results showed that RLR has a neutralization potential of approximately 83% as calcium carbonate (CaCO{sub 3}). Neutralization tests with most of the heavy metals associated with AMD showed removal efficiencies of over 99%. An unexpected benefit of utilizing RLR was the removal of hexavalent chromium Cr (VI) frommore » the aqueous phase. Due to an elevation in pH by RLR most AMD heavy metals are removed from solution by precipitation as their metal hydroxides. Cr (VI) however is not removed by pH elevation and therefore subsequent ongoing tests to elucidate the mechanism responsible for this reaction were conducted.« less

An Aptamer That Neutralizes R5 Strains of Human Immunodeficiency Virus Type 1 Blocks gp120-CCR5 Interaction

PubMed Central

Dey, Antu K.; Khati, Makobetsa; Tang, Min; Wyatt, Richard; Lea, Susan M.; James, William

2005-01-01

We recently described the isolation and structural characterization of 2′-fluoropyrimidine-substituted RNA aptamers that bind to gp120 of R5 strains of human immunodeficiency virus type 1 and thereby potently neutralize the infectivity of phylogenetically diverse R5 strains. Here we investigate the physical basis of their antiviral action. We show that both N-linked oligosaccharides and the variable loops V1/V2 and V3 are not required for binding of one aptamer, B40, to gp120. Using surface plasmon resonance binding analyses, we show that the aptamer binds to the CCR5-binding site on gp120 in a relatively CD4-independent manner, providing a mechanistic explanation for its neutralizing potency. PMID:16227301

Commissioning the GTA accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sander, O.R.; Atkins, W.H.; Bolme, G.O.

1992-09-01

The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth`s magnetic field and travel in straight lines unless they enter the earth`s atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H{sup -}more » beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor.« less

Commissioning the GTA accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sander, O.R.; Atkins, W.H.; Bolme, G.O.

1992-01-01

The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth's magnetic field and travel in straight lines unless they enter the earth's atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H{sup -}more » beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor.« less

Progress of beam diagnosis system for EAST neutral beam injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Y. J., E-mail: yjxu@ipp.ac.cn; Hu, C. D.; Yu, L.

Neutral beam injection has been recognized as one of the most effective means for plasma heating. According to the research plan of the EAST physics experiment, two sets of neutral beam injector (NBI) were built and operational in 2014. The paper presents the development of beam diagnosis system for EAST NBI and the latest experiment results obtained on the test-stand and EAST-NBI-1 and 2. The results show that the optimal divergence angle is (0.62°, 1.57°) and the full energy particle is up to 77%. They indicate that EAST NBI work properly and all targets reach or almost reach the designmore » targets. All these lay a solid foundation for the achievement of high quality plasma heating for EAST.« less

Positive emotions broaden the scope of attention and thought-action repertoires

PubMed Central

Fredrickson, Barbara L.; Branigan, Christine

2011-01-01

The broaden-and-build theory (Fredrickson, 1998, 2001) hypothesises that positive emotions broaden the scope of attention and thought-action repertoires. Two experiments with 104 college students tested these hypotheses. In each, participants viewed a film that elicited (a) amusement, (b) contentment, (c) neutrality, (d) anger, or (e) anxiety. Scope of attention was assessed using a global-local visual processing task (Experiment 1) and thought-action repertoires were assessed using a Twenty Statements Test (Experiment 2). Compared to a neutral state, positive emotions broadened the scope of attention in Experiment 1 and thought-action repertoires in Experiment 2. In Experiment 2, negative emotions, relative to a neutral state, narrowed thought-action repertoires. Implications for promoting emotional well-being and physical health are discussed. PMID:21852891

Vecksler-Macmillan phase stability for neutral atoms accelerated by a laser beam

NASA Astrophysics Data System (ADS)

Mel'nikov, I. V.; Haus, J. W.; Kazansky, P. G.

2003-05-01

We use a Fokker-Planck equation to study the phenomenon of accelerating a neutral atom bunch by a chirped optical beam. This method enables us to obtain a semi-analytical solution to the problem in which a wide range of parameters can be studied. In addition it provides a simple physical interpretation where the problem is reduced to an analogous problem of charged particles accelerators, that is, the Vecksler-Macmillan principle of phase stability. A possible experimental scenario is suggested, which uses a photonic crystal fiber as the guiding medium.

Simulation study of the ionizing front in the critical ionization velocity phenomenon

NASA Technical Reports Server (NTRS)

Machida, S.; Goertz, C. K.; Lu, G.

1988-01-01

The simulation of the critical ionization velocity for a neutral gas cloud moving across the static magnetic field is presented. A low-beta plasma is studied, using a two and a half-dimensional electrostatic code linked with the Plasma and Neutral Interaction Code (Goertz and Machida, 1987). The physics of the ionizing front and the instabilities which occur there are discussed. Results are presented from four numerical runs designed so that the effects of the charge separation field can be distinguished from the wave heating.

IMPACT OF PLANETARY GRAVITATION ON HIGH-PRECISION NEUTRAL ATOM MEASUREMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kucharek, H.; Möbius, E.; Lee, M. A.

2015-10-15

Measurements of energetic neutral atoms (ENAs) have been extremely successful in providing very important information on the physical processes inside and outside of our heliosphere. For instance, recent Interstellar Boundary Explorer (IBEX) observations have provided new insights into the local interstellar environment and improved measurements of the interstellar He temperature, velocity, and direction of the interstellar flow vector. Since particle collisions are rare, and radiation pressure is negligible for these neutrals, gravitational forces mainly determine the trajectories of neutral He atoms. Depending on the distance of an ENA to the source of a gravitational field and its relative speed andmore » direction, this can result in significant deflection and acceleration. In this paper, we investigate the impact of the gravitational effects of Earth, the Moon, and Jupiter on ENA measurements performed in Earth’s orbit. The results show that current analysis of the interstellar neutral parameters by IBEX is not significantly affected by planetary gravitational effects. We further studied the possibility of whether or not the Helium focusing cone of the Sun and Jupiter could be measured by IBEX and whether or not these cones could be used as an independent measure of the temperature of interstellar Helium.« less

Constraining Plasma Conditions of the IPT via Spectral Analysis of UV & Visible Emissions and Comparing with a Physical Chemistry Model

NASA Astrophysics Data System (ADS)

Nerney, E. G.; Bagenal, F.; Yoshioka, K.; Schmidt, C.

2017-12-01

Io emits volcanic gases into space at a rate of about a ton per second. The gases become ionized and trapped in Jupiter's strong magnetic field, forming a torus of plasma that emits 2 terawatts of UV emissions. In recent work re-analyzing UV emissions observed by Voyager, Galileo, & Cassini, we found plasma conditions consistent with a physical chemistry model with a neutral source of dissociated sulfur dioxide from Io (Nerney et al., 2017). In further analysis of UV observations from JAXA's Hisaki mission (using our spectral emission model) we constrain the torus composition with ground based observations. The physical chemistry model (adapted from Delamere et al., 2005) is then used to match derived plasma conditions. We correlate the oxygen to sulfur ratio of the neutral source with volcanic eruptions to understand the change in magnetospheric plasma conditions. Our goal is to better understand and constrain both the temporal and spatial variability of the flow of mass and energy from Io's volcanic atmosphere to Jupiter's dynamic magnetosphere.

The effect of a radial electric field on ripple-trapped ions observed by neutral particle fluxes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heikkinen, J.A.; Herrmann, W.; Kurki-Suonio, T.

1997-10-01

The effect of a radial electric field on nonthermal ripple-trapped ions is investigated using toroidal Monte Carlo simulations for edge tokamak plasmas. The increase in the neutral particle flux from the ions trapped in local magnetic wells observed by the charge exchange (CX) detector at a low confinement to high confinement transition at ASDEX (Axially Symmetric Divertor Experiment). Upgrade tokamak [{ital Proceedings of the 20th European Conference on Controlled Fusion and Plasma Physics}, Lisbon (European Physical Society, Petit-Lancy, Switzerland, 1993), Vol. 17C, Part I, p. 267] is reproduced in the simulations by turning on a radial electric field near themore » plasma periphery. The poloidal and toroidal angles at which the CX detector signal is most sensitive to the radial electric field are determined. A fast response time of the signal in the range of 50{endash}100 {mu}s to the appearance of the electric field can be found in the simulations with a relatively large half-width of the negative electric field region. {copyright} {ital 1997 American Institute of Physics.}« less

Numerical simulation of idealized front motion in neutral and stratified atmosphere with a hyperbolic system of equations

NASA Astrophysics Data System (ADS)

Yudin, M. S.

2017-11-01

In the present paper, stratification effects on surface pressure in the propagation of an atmospheric gravity current (cold front) over flat terrain are estimated with a non-hydrostatic finite-difference model of atmospheric dynamics. Artificial compressibility is introduced into the model in order to make its equations hyperbolic. For comparison with available simulation data, the physical processes under study are assumed to be adiabatic. The influence of orography is also eliminated. The front surface is explicitly described by a special equation. A time filter is used to suppress the non-physical oscillations. The results of simulations of surface pressure under neutral and stable stratification are presented. Under stable stratification the front moves faster and shows an abrupt pressure jump at the point of observation. This fact is in accordance with observations and the present-day theory of atmospheric fronts.

Atomic Physics Effects on Convergent, Child-Langmuir Ion Flow between Nearly Transparent Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santarius, John F.; Emmert, Gilbert A.

Research during this project at the University of Wisconsin Fusion Technology Institute (UW FTI) on ion and neutral flow through an arbitrary, monotonic potential difference created by nearly transparent electrodes accomplished the following: (1) developed and implemented an integral equation approach for atomic physics effects in helium plasmas; (2) extended the analysis to coupled integral equations that treat atomic and molecular deuterium ions and neutrals; (3) implemented the key deuterium and helium atomic and molecular cross sections; (4) added negative ion production and related cross sections; and (5) benchmarked the code against experimental results. The analysis and codes treat themore » species D0, D20, D+, D2+, D3+, D and, separately at present, He0 and He+. Extensions enhanced the analysis and related computer codes to include He++ ions plus planar and cylindrical geometries.« less

Plasma-Neutral Coupling on the Dark and Bright Sides of Antarctica

NASA Astrophysics Data System (ADS)

Chu, X.; Yu, Z.; Fong, W.; Chen, C.; Zhao, J.; Huang, W.; Roberts, B. R.; Fuller-Rowell, T. J.; Richmond, A. D.; Gerrard, A. J.; Weatherwax, A. T.; Gardner, C. S.

2014-12-01

The polar mesosphere and thermosphere provide a unique natural laboratory for studying the complex physical, chemical, neutral dynamical and electrodynamics processes in the Earth's atmosphere and space environment. McMurdo (geographic 77.83S, geomagnetic 80S) is located by the poleward edge of the aurora oval; so energetic particles may penetrate into the lower thermosphere and mesosphere along nearly vertical geomagnetic field lines. Lidar observations at McMurdo from December 2010 to 2014 have discovered several neutral atmosphere phenomena closely related to ionosphereic parameters and geomagnetic activity. For example, the diurnal tidal amplitude of temperatures not only increases super-exponentially from 100 to 110 km but also its growth rate becomes larger at larger Kp index. The lidar discovery of neutral iron (Fe) layers with gravity wave signatures in the thermosphere enabled the direct measurements of neutral temperatures from 30 to 170 km, revealing the neutral-ion coupling and aurora-enhanced Joule heating. A lidar 'marathon' of 174-hour continuous observations showed dramatic changes of composition (Fe atoms and ice particles) densities (over 40 times) in the mesopause region and their correlations to solar events. In this paper we will study the plasma-neutral coupling on the dark side of Antarctica via observation analysis and numerical modeling of the thermospheric Fe layers in the 100-200 km. A newly developed thermospheric Fe/Fe+ model is used to quantify how Fe+ ions are transported from their main deposition region to the E-F region and then neutralized to form Fe layers under dark polar conditions. We will also study the plasma-neutral coupling on the bright side of Antarctica via analyzing Fe events in summer. Complementary observations will be combined to show how the extreme changes of Fe layers are related to aurora particle precipitation and visible/sub-visible ice particles. These observations and studies will open new areas of scientific inquiry regarding the composition, chemistry, neutral dynamics, thermodynamics, and electrodynamics of one of the least-understood regions in the atmosphere.

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

NASA Astrophysics Data System (ADS)

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 abundances of CH+. Compared to previous works, our multiphase simulations reduce the spread in vd, and our self-consistent treatment of the ionisation leads to much reduced vd. Nevertheless, our resolution study shows that this velocity distribution is not converged: the ion-neutral drift has a higher impact on CH+ at higher resolution. On the other hand, our ideal MHD simulations do not include ambipolar diffusion, which would yield lower drift velocities. Conclusions: Within these limitations, we conclude that warm H2 is a key ingredient in the efficient formation of CH+ and that the ambipolar diffusion has very little influence on the abundance of CH+, mainly due to the small drift velocities obtained. However, we point out that small-scale processes and other non-thermal processes not included in our MHD simulation may be of crucial importance, and higher resolution studies with better controlled dissipation processes are needed.

The Analysis of Constitutions of Traditional Chinese Medicine in Relation to Cerebral Infarction in a Chinese Sample.

PubMed

Liu, Jiaqi; Xu, Fei; Mohammadtursun, Nabijan; Lv, Yubao; Tang, Zihui; Dong, Jingcheng

2018-05-01

To investigate the relationships between the constitutions of Traditional Chinese Medicine (TCM) and patients with cerebral infarction (CI) in a Chinese sample. A total of 3748 participants with complete data were available for data analysis. All study subjects underwent complete clinical baseline characteristics' evaluation, including a physical examination and response to a structured, nurse-assisted, self-administrated questionnaire. A population of 2010 neutral participants were used as the control group. Multiple variable regression (MLR) were employed to estimate the relationship between constitutions of TCM and the outcome. A cross-sectional study was conducted to evaluate the association of body constitution of TCM and CI. Communications and healthcare centers in Shanghai. A total of 3748 participants with complete data were available for data analysis. All study subjects underwent complete clinical baseline characteristics' evaluation, including a physical examination and response to a structured, nurse-assisted, self-administrated questionnaire. A population of 2010 neutral participants were used as the control group. MLR were employed to estimate the relationship between constitutions of TCM and the outcome. The prevalence of CI was 2.84% and 4.66% in neutral participants and yang-deficient participants (p = 0.012), respectively. Univariate analysis demonstrated a positive correlation between yang deficiency and CI. After adjustment for relevant potential confounding factors, the MLR detected significant associations between yang deficiency and CI (odds ratio = 1.44, p = 0.093). A yang-deficient constitution was significantly and independently associated with CI. A higher prevalence of CI was found in yang-deficient participants as compared with neutral participants.

Weathering Profiles in Phosphorus-Rich Rocks at Gusev Crater, Mars, Suggest Dissolution of Phosphate Minerals into Potentially Habitable Near-Neutral Waters.

PubMed

Adcock, Christopher T; Hausrath, Elisabeth M

2015-12-01

Abundant evidence indicates that significant surface and near-surface liquid water has existed on Mars in the past. Evaluating the potential for habitable environments on Mars requires an understanding of the chemical and physical conditions that prevailed in such aqueous environments. Among the geological features that may hold evidence of past environmental conditions on Mars are weathering profiles, such as those in the phosphorus-rich Wishstone-class rocks in Gusev Crater. The weathering profiles in these rocks indicate that a Ca-phosphate mineral has been lost during past aqueous interactions. The high phosphorus content of these rocks and potential release of phosphorus during aqueous interactions also make them of astrobiological interest, as phosphorus is among the elements required for all known life. In this work, we used Mars mission data, laboratory-derived kinetic and thermodynamic data, and data from terrestrial analogues, including phosphorus-rich basalts from Idaho, to model a conceptualized Wishstone-class rock using the reactive transport code CrunchFlow. Modeling results most consistent with the weathering profiles in Wishstone-class rocks suggest a combination of chemical and physical erosion and past aqueous interactions with near-neutral waters. The modeling results also indicate that multiple Ca-phosphate minerals are likely in Wishstone-class rocks, consistent with observations of martian meteorites. These findings suggest that Gusev Crater experienced a near-neutral phosphate-bearing aqueous environment that may have been conducive to life on Mars in the past. Mars-Gusev Crater-Wishstone-Reactive transport modeling-CrunchFlow-Aqueous interactions-Neutral pH-Habitability.

Disruption Neutral Point Experiment on Alcator C-Mod

NASA Astrophysics Data System (ADS)

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.

A study of the accuracy of neutrally buoyant bubbles used as flow tracers in air

NASA Technical Reports Server (NTRS)

Kerho, Michael F.

1993-01-01

Research has been performed to determine the accuracy of neutrally buoyant and near neutrally buoyant bubbles used as flow tracers in air. Theoretical, computational, and experimental results are presented to evaluate the dynamics of bubble trajectories and factors affecting their ability to trace flow-field streamlines. The equation of motion for a single bubble was obtained and evaluated using a computational scheme to determine the factors which affect a bubble's trajectory. A two-dimensional experiment was also conducted to experimentally determine bubble trajectories in the stagnation region of NACA 0012 airfoil at 0 deg angle of attack using a commercially available helium bubble generation system. Physical properties of the experimental bubble trajectories were estimated using the computational scheme. These properties included the density ratio and diameter of the individual bubbles. the helium bubble system was then used to visualize and document the flow field about a 30 deg swept semispan wing with simulated glaze ice. Results were compared to Navier-Stokes calculations and surface oil flow visualization. The theoretical and computational analysis have shown that neutrally buoyant bubbles will trace even the most complex flow patterns. Experimental analysis revealed that the use of bubbles to trace flow patterns should be limited to qualitative measurements unless care is taken to ensure neutral buoyancy. This is due to the difficulty in the production of neutrally buoyant bubbles.

Effects of Aging Stereotype Threat on Working Self-Concepts: An Event-Related Potentials Approach

PubMed Central

Zhang, Baoshan; Lin, Yao; Gao, Qianyun; Zawisza, Magdalena; Kang, Qian; Chen, Xuhai

2017-01-01

Although the influence of stereotype threat (ST) on working self-concepts has been highlighted in recent years, its neural underpinnings are unclear. Notably, the aging ST, which largely influences older adults’ cognitive ability, mental and physical health, did not receive much attention. In order to investigate these issues, electroencephalogram (EEG) data were obtained from older adults during a modified Stroop task using neutral words, positive and negative self-concept words in aging ST vs. neutral control conditions. Results showed longer reaction times (RTs) for identifying colors of words under the aging ST compared to the neutral condition. More importantly, the negative self-concept elicited more positive late P300 amplitudes and enhanced theta band activities compared to the positive self-concept or neutral words under the aging ST condition, whereas no difference was found between these self-concepts and neutral words in the control condition. Furthermore, the aging ST induced smaller theta band synchronization and enhanced alpha band synchronization compared to the control condition. Moreover, we also observed valence differences in self-concepts where the negative self-concept words reduced early P150/N170 complex relative to neutral words. These findings suggest that priming ST could activate negative self-concepts as current working self-concept, and that this influence occurred during a late neural time course. PMID:28747885

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedman, A.; Barnard, J.J.; Briggs, R.J.

The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL), a collaborationof LBNL, LLNL, and PPPL, has achieved 60-fold pulse compression of ion beams on the Neutralized Drift Compression eXperiment (NDCX) at LBNL. In NDCX, a ramped voltage pulse from an induction cell imparts a velocity"tilt" to the beam; the beam's tail then catches up with its head in a plasma environment that provides neutralization. The HIFS-VNL's mission is to carry out studies of Warm Dense Matter (WDM) physics using ion beams as the energy source; an emerging thrust is basic target physics for heavy ion-driven Inertial Fusion Energy (IFE). Thesemore » goals require an improved platform, labeled NDCX-II. Development of NDCX-II at modest cost was recently enabled by the availability of induction cells and associated hardware from the decommissioned Advanced Test Accelerator (ATA) facility at LLNL. Our initial physics design concept accelerates a ~;;30 nC pulse of Li+ ions to ~;;3 MeV, then compresses it to ~;;1 ns while focusing it onto a mm-scale spot. It uses the ATA cells themselves (with waveforms shaped by passive circuits) to impart the final velocity tilt; smart pulsers provide small corrections. The ATA accelerated electrons; acceleration of non-relativistic ions involves more complex beam dynamics both transversely and longitudinally. We are using analysis, an interactive one-dimensional kinetic simulation model, and multidimensional Warp-code simulations to develop the NDCX-II accelerator section. Both LSP and Warp codes are being applied to the beam dynamics in the neutralized drift and final focus regions, and the plasma injection process. The status of this effort is described.« less

Electroweak penguins at LHCb

NASA Astrophysics Data System (ADS)

He, Jibo; LHCb Collaboration

2016-04-01

Electroweak penguin decays are flavour-changing neutral current processes, and are highly suppressed in the Standard Model. They can only proceed via loop diagrams. Such decays may receive contributions from New Physics and change their decay behaviours like decay rate and angular distribution. Studying the properties of these decays thus provides a powerful method to probe for New Physics. In this contribution the most recent LHCb results on electroweak penguin decays are reported.

Electron-hole collision limited transport in charge-neutral bilayer graphene

NASA Astrophysics Data System (ADS)

Nam, Youngwoo; Ki, Dong-Keun; Soler-Delgado, David; Morpurgo, Alberto F.

2017-12-01

Ballistic transport occurs whenever electrons propagate without collisions deflecting their trajectory. It is normally observed in conductors with a negligible concentration of impurities, at low temperature, to avoid electron-phonon scattering. Here, we use suspended bilayer graphene devices to reveal a new regime, in which ballistic transport is not limited by scattering with phonons or impurities, but by electron-hole collisions. The phenomenon manifests itself in a negative four-terminal resistance that becomes visible when the density of holes (electrons) is suppressed by gate-shifting the Fermi level in the conduction (valence) band, above the thermal energy. For smaller densities, transport is diffusive, and the measured conductivity is reproduced quantitatively, with no fitting parameters, by including electron-hole scattering as the only process causing velocity relaxation. Experiments on a trilayer device show that the phenomenon is robust and that transport at charge neutrality is governed by the same physics. Our results provide a textbook illustration of a transport regime that had not been observed previously and clarify the nature of conduction through charge-neutral graphene under conditions in which carrier density inhomogeneity is immaterial. They also demonstrate that transport can be limited by a fully electronic mechanism, originating from the same microscopic processes that govern the physics of Dirac-like plasmas.

Quantum oscillations in insulators with neutral Fermi surfaces

NASA Astrophysics Data System (ADS)

Sodemann, Inti; Chowdhury, Debanjan; Senthil, T.

2018-02-01

We develop a theory of quantum oscillations in insulators with an emergent Fermi sea of neutral fermions minimally coupled to an emergent U(1 ) gauge field. As pointed out by Motrunich [Phys. Rev. B 73, 155115 (2006), 10.1103/PhysRevB.73.155115], in the presence of a physical magnetic field the emergent magnetic field develops a nonzero value leading to Landau quantization for the neutral fermions. We focus on the magnetic field and temperature dependence of the analog of the de Haas-van Alphen effect in two and three dimensions. At temperatures above the effective cyclotron energy, the magnetization oscillations behave similarly to those of an ordinary metal, albeit in a field of a strength that differs from the physical magnetic field. At low temperatures, the oscillations evolve into a series of phase transitions. We provide analytical expressions for the amplitude and period of the oscillations in both of these regimes and simple extrapolations that capture well their crossover. We also describe oscillations in the electrical resistivity of these systems that are expected to be superimposed with the activated temperature behavior characteristic of their insulating nature and discuss suitable experimental conditions for the observation of these effects in mixed-valence insulators and triangular lattice organic materials.

Ion and neutral dynamics in Hall plasma accelerator ionization instabilities

NASA Astrophysics Data System (ADS)

Lucca Fabris, Andrea; Young, Christopher; Cappelli, Mark

2015-09-01

Hall thrusters, the extensively studied E × B devices used for space propulsion applications, are rife with instabilities and fluctuations. Many are thought to be fundamentally linked to microscopic processes like electron transport across magnetic field lines and propellant ionization that in turn affect macroscopic properties like device performance and lifetime. One of the strongest oscillatory regimes is the ``breathing mode,'' characterized by a propagating ionization front, time-varying ion acceleration profiles, and quasi-periodic 10-50 kHz current oscillations. Determining the temporal and spatial evolution of plasma properties is critical to achieving a fundamental physical understanding of these processes. We present non-intrusive laser-induced fluorescence measurements of the local ion and neutral velocity distribution functions synchronized with the breathing mode oscillations. Measurements reveal strong ion velocity fluctuations, multiple ion populations arising in narrow time windows throughout the near-field plume, and the periodic population and depopulation of neutral excited states. Analyzing these detailed experimental results in the context of the existing literature clarifies the fundamental physical processes underlying the breathing mode. This work is sponsored by the U.S. Air Force Office of Scientific Research with Dr. M. Birkan as program manager. C.Y. acknowledges support from the DOE NSSA Stewardship Science Graduate Fellowship under contract DE-FC52-08NA28752.

Modulation of ENA in the heliosphere

NASA Astrophysics Data System (ADS)

Bzowski, Maciej; Kubiak, Marzena; Czechowski, Andrzej

Energetic Neutral Atoms (ENA), an important part of heliospheric physics, have recently en-joyed an increased interest because of the breakthrough observations by the NASA SMEX mission IBEX. Generally, ENA appear as a product of charge exchange reaction between an energetic ion and a neutral gas atom. Being insensitive to electromagnetic forces, ENA run away freely from their birth sites and can carry information on the physical state of the parent plasma on (somewhat energy-dependent) distances well in excess of 100 AU. The ENA fluxes exhibit modulation due to time variations of their source function due to modulation of solar wind on time scales from days to solar cycle and due to large-scale variation in the latitude structure of the solar wind, as well as to the variations in the loss rate due to re-ionization. Once created, the ENA flux suffers losses mostly due to photoionization by solar EUV photons, but also to charge exchange and electron impact. We will review the variation of survival prob-ability of the ENA created in the inner heliosheath and observed by spacecraft on Mars, Earth, and Venus orbits (like Mars Express, IBEX, and Venus Express) and solar-cycle modulation of the radially-expanding spectral flux of ENA consisting of the solar wind protons and alpha particles transcharged on the neutral interstellar gas inside the heliosphere.

Modelling removal mechanisms of Pb, Cu, Zn and Cd in acidic groundwater during the neutralization by ambient surface and ground waters

USGS Publications Warehouse

Paulson, Anthony J.; Balistrieri, Laurie S.

1999-01-01

Removal of Pb, Cu, Zn, and Cd during neutralization of acid rock drainage is examined using model simulations of field conditions and laboratory experiments involving mixing of natural drainage and surface waters or groundwaters. The simulations consider sorption onto hydrous Fe and Al oxides and particulate organic carbon, mineral precipitation, and organic and inorganic solution complexation of metals for two physical systems where newly formed oxides and particulate organic matter are either transported or retained along the chemical pathway. The calculations indicate that metal removal is a strong function of the physical system. Relative to direct discharge of ARD into streams, lower metal removals are observed where ARD enters streamwaters during the latter stages of neutralization by ambient groundwater after most of the Fe has precipitated and been retained in the soils. The mixing experiments, which represent the field simulations, also demonstrated the importance of dissolved metal to particle Fe ratios in controlling dissolved metal removal along the chemical pathway. Finally, model calculations indicate that hydrous Fe oxides and particulate organic carbon are more important than hydrous Al oxides in removing metals and that both inorganic and organic complexation must be considered when modeling metal removal from aquatic systems that are impacted by sulfide oxidation.

The formation and evolution of reconnection-driven, slow-mode shocks in a partially ionised plasma

NASA Astrophysics Data System (ADS)

Hillier, A.; Takasao, S.; Nakamura, N.

2016-06-01

The role of slow-mode magnetohydrodynamic (MHD) shocks in magnetic reconnection is of great importance for energy conversion and transport, but in many astrophysical plasmas the plasma is not fully ionised. In this paper, we use numerical simulations to investigate the role of collisional coupling between a proton-electron, charge-neutral fluid and a neutral hydrogen fluid for the one-dimensional (1D) Riemann problem initiated in a constant pressure and density background state by a discontinuity in the magnetic field. This system, in the MHD limit, is characterised by two waves. The first is a fast-mode rarefaction wave that drives a flow towards a slow-mode MHD shock wave. The system evolves through four stages: initiation, weak coupling, intermediate coupling, and a quasi-steady state. The initial stages are characterised by an over-pressured neutral region that expands with characteristics of a blast wave. In the later stages, the system tends towards a self-similar solution where the main drift velocity is concentrated in the thin region of the shock front. Because of the nature of the system, the neutral fluid is overpressured by the shock when compared to a purely hydrodynamic shock, which results in the neutral fluid expanding to form the shock precursor. Once it has formed, the thickness of the shock front is proportional to ξ I-1.2 , which is a smaller exponent than would be naively expected from simple scaling arguments. One interesting result is that the shock front is a continuous transition of the physical variables of subsonic velocity upstream of the shock front (a c-shock) to a sharp jump in the physical variables followed by a relaxation to the downstream values for supersonic upstream velocity (a j-shock). The frictional heating that results from the velocity drift across the shock front can amount to ~2 per cent of the reference magnetic energy.

Electric fields measured by ISEE-1 within and near the neutral sheet during quiet and active times

NASA Technical Reports Server (NTRS)

Cattell, C. A.; Mozer, F. S.

1982-01-01

An understanding of the physical processes occurring in the magnetotail and plasmasheet during different interplanetary magnetic field orientations and differing levels of ground magnetic activity is crucial for the development of a theory of energy transfer from the solar wind to the particles which produce auroral arcs. In the present investigation, the first observations of electric fields during neutral sheet crossings are presented, taking into account the statistical correlations of the interplanetary magnetic field direction and ground activity with the character of the electric field. The electric field data used in the study were obtained from a double probe experiment on the ISEE-1 satellite. The observations suggest that turbulent electric and magnetic fields are intimately related to plasma acceleration in the neutral sheet and to the processes which create auroral particles.

Long-range attraction of an ultrarelativistic electron beam by a column of neutral plasma

NASA Astrophysics Data System (ADS)

Adli, E.; Lindstrøm, C. A.; Allen, J.; Clarke, C. I.; Frederico, J.; Gessner, S. J.; Green, S. Z.; Hogan, M. J.; Litos, M. D.; O'Shea, B.; Yakimenko, V.; An, W.; Clayton, C. E.; Marsh, K. A.; Mori, W. B.; Joshi, C.; Vafaei-Najafabadi, N.; Corde, S.; Lu, W.

2016-10-01

We report on the experimental observation of the attraction of a beam of ultrarelativistic electrons towards a column of neutral plasma. In experiments performed at the FACET test facility at SLAC we observe that an electron beam moving parallel to a neutral plasma column, at an initial distance of many plasma column radii, is attracted into the column. Once the beam enters the plasma it drives a plasma wake similar to that of an electron beam entering the plasma column head-on. A simple analytical model is developed in order to capture the essential physics of the attractive force. The attraction is further studied by 3D particle-in-cell numerical simulations. The results are an important step towards better understanding of particle beam-plasma interactions in general and plasma wakefield accelerator technology in particular.

The neutral mass spectrometer on Dynamics Explorer B

NASA Technical Reports Server (NTRS)

Carignan, G. R.; Block, B. P.; Maurer, J. C.; Hedin, A. E.; Reber, C. A.; Spencer, N. W.

1981-01-01

A neutral gas mass spectrometer has been developed to satisfy the measurement requirements of the Dynamics Explorer mission. The mass spectrometer, a quadrupole, will measure the abundances of neutral species in the region 300-500 km in the earth's atmosphere. These measurements will be used in concert with other simultaneous observations on Dynamics Explorer to study the physical processes involved in the interactions of the magnetosphere-ionosphere-atmosphere system. The instrument, which is similar to that flown on Atmosphere Explorer, employs an electron beam ion source operating in the closed mode and a discrete dynode multiplier as a detector. The mass range is 22 to 50 amu. The abundances of atomic oxygen, molecular nitrogen, helium, argon, and possibly atomic nitrogen will be measured to an accuracy of about + or - 15% over the specified altitude range, with a temporal resolution of one second.

Infrared Emission and Thermal Processes in Spiral Galaxies

NASA Technical Reports Server (NTRS)

Mundy, Lee; Wolfire, Mark

1999-01-01

In this research we constructed theoretical models of the infrared and submillimeter line and continuum emission from the neutral interstellar medium in the Milky Way and external galaxies. The model line intensities were compared to observations of the Galactic disk and several galaxies to determine the average physical properties of the neutral gas including the density, temperature, and ultraviolet radiation field which illuminates the gas. In addition we investigated the heating mechanisms in the Galactic disk and estimated the emission rate of the [C 11] 158 micrometer line as a function of position in the Galaxy. We conclude that the neutral gas is heated mainly by the grain photoelectric effect and that a two phase (CNM+WNM) is possible between Galactic radii R = 3 kpc and R = 18 kpc. Listings of meeting presentations and publications are included.

Chemistry in Titan

NASA Astrophysics Data System (ADS)

Plessis, S.; Carrasco, N.; Pernot, P.

2009-04-01

Modelling the chemical composition of Titan's ionosphere is a very challenging issue. Latest works perform either inversion of CASSINI's INMS mass spectra (neutral[1] or ion[2]), or design coupled ion-neutral chemistry models[3]. Coupling ionic and neutral chemistry has been reported to be an essential feature of accurate modelling[3]. Electron Dissociative Recombination (EDR), where free electrons recombine with positive ions to produce neutral species, is a key component of ion-neutral coupling. There is a major difficulty in EDR modelling: for heavy ions, the distribution of neutral products is incompletely characterized by experiments. For instance, for some hydrocarbon ions only the carbon repartition is measured, leaving the hydrogen repartition and thus the exact neutral species identity unknown[4]. This precludes reliable deterministic modelling of this process and of ion-neutral coupling. We propose a novel stochastic description of the EDR chemical reactions which enables efficient representation and simulation of the partial experimental knowledge. The description of products distribution in multi-pathways reactions is based on branching ratios, which should sum to unity. The keystone of our approach is the design of a probability density function accounting for all available informations and physical constrains. This is done by Dirichlet modelling which enables one to sample random variables whose sum is constant[5]. The specifics of EDR partial uncertainty call for a hierarchiral Dirichlet representation, which generalizes our previous work[5]. We present results on the importance of ion-neutral coupling based on our stochastic model. C repartition H repartition (measured) (unknown ) → C4H2 + 3H2 + H .. -→ C4 . → C4H2 + 7H → C3H8. + CH C4H+9 + e- -→ C3 + C .. → C3H3 + CH2 + 2H2 → C2H6 + C2H2 + H .. -→ C2 + C2 . → 2C2H2 + 2H2 + H (1) References [1] J. Cui, R.V. Yelle, V. Vuitton, J.H. Waite Jr., W.T. Kasprzak, D.A. Gell, H.B. Niemann, I.C.F. Müller-Wodarg, N. Borggren, G.G. Fletcher, E.L. Patrick, E. Raaen, and B.A. Magee. Analysis of Titan's neutral upper atmosphere from Cassini ion neutral mass spectrometer measurements. Icarus, In Press, Accepted Manuscript:-, 2008. [2] V. Vuitton, R. V. Yelle, and M.J. McEwan. Ion chemistry and N-containing molecules in Titan's upper atmosphere. Icarus, 191:722-742, 2007. [3] V. De La Haye, J.H. Waite Jr., T.E. Cravens, I.P. Robertson, and S. Lebonnois. Coupled ion and neutral rotating model of Titan's upper atmosphere. Icarus, 197(1):110 - 136, 2008. [4] J. B. A. Mitchell, C. Rebrion-Rowe, J. L. Le Garrec, G. Angelova, H. Bluhme, K. Seiersen, and L. H. Andersen. Branching ratios for the dissociative recombination of hydrocarbon ions. I: The cases of C4H9+ and C4H5+. International Journal of Mass Spectrometry, 227(2):273-279, June 2003. [5] N. Carrasco and P. Pernot. Modeling of branching ratio uncertainty in chemical networks by Dirichlet distributions. Journal of Physical Chemistry A, 11(18):3507-3512, 2007.

Experimental constraints from flavour changing processes and physics beyond the Standard Model.

PubMed

Gersabeck, M; Gligorov, V V; Serra, N

Flavour physics has a long tradition of paving the way for direct discoveries of new particles and interactions. Results over the last decade have placed stringent bounds on the parameter space of physics beyond the Standard Model. Early results from the LHC, and its dedicated flavour factory LHCb, have further tightened these constraints and reiterate the ongoing relevance of flavour studies. The experimental status of flavour observables in the charm and beauty sectors is reviewed in measurements of CP violation, neutral meson mixing, and measurements of rare decays.

A Neutral Particle Analyser Proposed On Board Bepicolombo Planetary Orbiter: Serena (searching For Exospheric Refilling and Emitted Neutral Abundances)

NASA Astrophysics Data System (ADS)

Orsini, S.; Npa-Serena Team

The Neutral Particle Analyser SERENA, proposed on board the BepiColombo Mer- cury Planetary Orbiter (MPO), has the purpose of investigating the Hermean exo- spheric and energetic neutral populations. Local and detailed analysis of the exo- spheric composition will be performed by a ram-pointing sensor (MAIA), while en- ergetic neutrals produced through sputtering and charge-exchange processes will be collected by two nadir-pointing sensors (L-ENA, MH-ENA). A central problem in the understanding of the evolution of solar system bodies is the role played by the so- lar wind, solar radiation and micro-meteorite bombardment in controlling mass losses. The direct in situ detection of the Hermean exosphere, the gas evolving from the planet as a product of the different physical processes acting onto the surface, is of crucial importance to understand the past and present evolution of the crust. Current knowl- edge of the origin and evolution of the solar system is based on detailed measurement of chemical, elemental, and isotopic composition of matter. The proposed instrument suite is unique in its capability to perform quantitative analysis and resolve exospheric gas composition under all these three aspects. The value of neutral particles mea- surements for getting a comprehensive picture of the solar wind-planets interaction has been appreciated since the late eighties. Comparison of the measurements in the Mercury environment with those achieved by neutral particle imagers already flying around Earth (IMAGE), Mars (Mars Express), Jupiter and Saturn (Cassini) will allow comparative investigations of evolution and dynamics of planetary magnetospheres.

A survey of interstellar neutral potassium. I - Abundances and physical conditions in clouds toward 188 early-type stars

NASA Technical Reports Server (NTRS)

Chaffee, F. H., Jr.; White, R. E.

1982-01-01

Observations of interstellar absorption in the resonance doublet 7664, 7698 A of neutral potassium toward 188 early-type stars at a spectral resolution of 8 km/s are reported. The 7664 A line is successfully separated from nearly coincident telluric O2 absorption for all but a few of the 165 stars for which K I absorption is detected, making possible an abundance analysis by the doublet ratio method. The relationships between the potassium abundances and other atomic abundances, the abundance of molecular hydrogen, and interstellar reddening are investigated.

Comparisons of neutrino event generators from an oscillation-experiment perspective

NASA Astrophysics Data System (ADS)

Mayer, Nathan

2015-05-01

Monte Carlo generators are crucial to the analysis of high energy physics data, ideally giving a baseline comparison between the state-of-art theoretical models and experimental data. Presented here is a comparison between three of final state distributions from the GENIE, Neut, NUANCE, and NuWro neutrino Monte Carlo event generators. The final state distributions chosen for comparison are: the electromagnetic energy fraction in neutral current interactions, the energy of the leading π0 vs. the scattering angle for neutral current interactions, and the muon energy vs. scattering angle of νµ charged current interactions.

Sodium dopants in helium clusters: Structure, equilibrium and submersion kinetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calvo, F.

Alkali impurities bind to helium nanodroplets very differently depending on their size and charge state, large neutral or charged dopants being wetted by the droplet whereas small neutral impurities prefer to reside aside. Using various computational modeling tools such as quantum Monte Carlo and path-integral molecular dynamics simulations, we have revisited some aspects of the physical chemistry of helium droplets interacting with sodium impurities, including the onset of snowball formation in presence of many-body polarization forces, the transition from non-wetted to wetted behavior in larger sodium clusters, and the kinetics of submersion of small dopants after sudden ionization.

Physics and astrophysics from a lunar base; Proceedings of the 1st NASA Workshop, Stanford, CA, May 19, 20, 1989

NASA Technical Reports Server (NTRS)

Potter, A. E. (Editor); Wilson, T. L. (Editor)

1990-01-01

The present conference on physics and astrophysics from a lunar base encompasses space physics, cosmic ray physics, neutrino physics, experiments in gravitation and general relativity, gravitational radiation physics, cosmic background radiation, particle astrophysics, surface physics, and the physics of gamma rays and X-rays. Specific issues addressed include space-plasma physics research at a lunar base, prospects for neutral particle imaging, the atmosphere as particle detector, medium- and high-energy neutrino physics from a lunar base, muons on the moon, a search for relic supernovae antineutrinos, and the use of clocks in satellites orbiting the moon to test general relativity. Also addressed are large X-ray-detector arrays for physics experiments on the moon, and the measurement of proton decay, arcsec-source locations, halo dark matter and elemental abundances above 10 exp 15 eV at a lunar base.

Experimental Investigation of Neutral Species from Micrometeoroid Bombardment

NASA Astrophysics Data System (ADS)

Collette, A.; Sternovsky, Z.; Rocha, J. R.; Munsat, T. L.; Horanyi, M.

2014-12-01

Surface-boundary exospheres exist in a balance between source and loss processes. An important area of uncertainty, highlighted by the MESSENGER observations of Mg and Ca at Mercury, and the recently concluded LADEE observations at the Moon, is the role of micrometeoroid bombardment as a source process for liberating surface species. Unlike sputtering or photon stimulated desorption processes, the physics of micrometeoroid impacts are still poorly understood; in particular, no comprehensive model exists to predict partitioning of impact products between ejecta fragments, charged particles, and neutrals. We present initial experiments at the IMPACT dust accelerator facility (University of Colorado Boulder) aimed at directly measuring the fraction of neutral species liberated in micrometeoroid impacts. Simulated micrometeoroids (micron- and submicron-sized iron spheres) are fired at targets containing refractory elements, including fused silica (SiO2), sapphire (Al2O3), and magnesium fluoride (MgF2). Total quantities of specific impact-generated neutral species are measured using a mass spectrometer, as a function of impactor speed and mass, and compared with well-established scaling laws for charged particle production.

Hybrid 3D model for the interaction of plasma thruster plumes with nearby objects

NASA Astrophysics Data System (ADS)

Cichocki, Filippo; Domínguez-Vázquez, Adrián; Merino, Mario; Ahedo, Eduardo

2017-12-01

This paper presents a hybrid particle-in-cell (PIC) fluid approach to model the interaction of a plasma plume with a spacecraft and/or any nearby object. Ions and neutrals are modeled with a PIC approach, while electrons are treated as a fluid. After a first iteration of the code, the domain is split into quasineutral and non-neutral regions, based on non-neutrality criteria, such as the relative charge density and the Debye length-to-cell size ratio. At the material boundaries of the former quasineutral region, a dedicated algorithm ensures that the Bohm condition is met. In the latter non-neutral regions, the electron density and electric potential are obtained by solving the coupled electron momentum balance and Poisson equations. Boundary conditions for both the electric current and potential are finally obtained with a plasma sheath sub-code and an equivalent circuit model. The hybrid code is validated by applying it to a typical plasma plume-spacecraft interaction scenario, and the physics and capabilities of the model are finally discussed.

Long-pulse power-supply system for EAST neutral-beam injectors

NASA Astrophysics Data System (ADS)

Liu, Zhimin; Jiang, Caichao; Pan, Junjun; Liu, Sheng; Xu, Yongjian; Chen, Shiyong; Hu, Chundong; NBI Team

2017-05-01

The long-pulse power-supply system equipped for the 4 MW beam-power ion source is comprised of three units at ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences): one for the neutral-beam test stand and two for the EAST neutral-beam injectors (NBI-1 and NBI-2, respectively). Each power supply system consists of two low voltage and high current DC power supplies for plasma generation of the ion source, and two high voltage and high current DC power supplies for the accelerator grid system. The operation range of the NB power supply is about 80 percent of the design value, which is the safe and stable operation range. At the neutral-beam test stand, a hydrogen ion beam with a beam pulse of 150 s, beam power of 1.5 MW and beam energy of 50 keV was achieved during the long-pulse testing experiments. The result shows that the power-supply system meets the requirements of the EAST-NBIs fully and lays a basis for achieving plasma heating.

The effect of residual water on antacid properties of sucralfate gel dried by microwaves.

PubMed

Gainotti, Alessandro; Losi, Elena; Colombo, Paolo; Santi, Patrizia; Sonvico, Fabio; Baroni, Daniela; Massimo, Gina; Colombo, Gaia; Del Gaudio, Pasquale

2006-01-20

The aim of this work was to study the acid neutralization characteristics of microwave-dried sucralfate gel in relation to the water content and physical structure of the substance. Several dried sucralfate gels were compared with humid sucralfate gel and sucralfate nongel powder in terms of neutralization rate and buffering capacity. Humid sucralfate gel and microwave-dried gel exhibited antacid effectiveness. In particular, the neutralization rate of dried gel powders was inversely related to the water content: as the water content of dried powders decreased, the acid reaction rate linearly increased. The relationship was due to the different morphology of dried sucralfate gels. In fact, the porosity of the dried samples increased with the water reduction. However, the acid neutralization equivalent revealed that the dried sucralfate gel became more resistant to acid attack in the case of water content below 42%. Then, the microwave drying procedure had the opposite effect on the reactivity of the aluminum hydroxide component of dried sucralfate gel powders, since the rate of the reaction increased whereas the buffering capacity decreased as the amount of water was reduced.

The effect of residual water on antacid properties of sucralfate gel dried by microwaves.

PubMed

Gainotti, Alessandro; Losi, Elena; Colombo, Paolo; Santi, Patrizia; Sonvico, Fabio; Baroni, Daniela; Massimo, Gina; Colombo, Gaia; Del Gaudio, Pasquale

2006-03-01

The aim of this work was to study the acid neutralization characteristics of microwave-dried sucralfate gel in relation to the water content and physical structure of the substance. Several dried sucralfate gels were compared with humid sucralfate gel and sucralfate nongel powder in terms of neutralization rate and buffering capacity. Humid sucralfate gel and microwave-dried gel exhibited antacid effectiveness. In particular, the neutralization rate of dried gel powders was inversely related to the water content: as the water content of dried powders decreased, the acid reaction rate linearly increased. The relationship was due to the different morphology of dried sucralfate gels. In fact, the porosity of the dried samples increased with the water reduction. However, the acid neutralization equivalent revealed that the dried sucralfate gel became more resistant to acid attack in the case of water content below 42%. Then, the microwave drying procedure had the opposite effect on the reactivity of the aluminum hydroxide component of dried sucralfate gel powders, since the rate of the reaction increased whereas the buffering capacity decreased as the amount of water was reduced.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prost, L.; Carneiro, J.-P.; Shemyakin, A.

In a Low Energy Beam Transport line (LEBT), the emittance growth due to the beam’s space charge is typically suppressed by way of neutralization from either electrons or ions, which originate from ionization of the background gas. In cases where the beam is chopped, the neutralization pattern usually changes throughout the beginning of the pulse, causing the Twiss parameters to differ significantly from their steady state values, which, in turn, may result in beam losses downstream. For a modest beam perveance, there is an alternative solution, in which the beam is kept un-neutralized in the portion of the LEBT thatmore » contains the chopper. The emittance can be nearly preserved if the transition to the un-neutralized section occurs where the beam exhibits low transverse tails. This report introduces the rationale for the proposed scheme and formulates the physical arguments for it as well as its limitations. An experimental realization of the scheme was carried out at Fermilab’s PIP2IT where low beam emittance dilution was demonstrated for a 5 mA, 30 keV H- beam.« less

Differences between Doppler velocities of ions and neutral atoms in a solar prominence

NASA Astrophysics Data System (ADS)

Anan, T.; Ichimoto, K.; Hillier, A.

2017-05-01

Context. In astrophysical systems with partially ionized plasma, the motion of ions is governed by the magnetic field while the neutral particles can only feel the magnetic field's Lorentz force indirectly through collisions with ions. The drift in the velocity between ionized and neutral species plays a key role in modifying important physical processes such as magnetic reconnection, damping of magnetohydrodynamic waves, transport of angular momentum in plasma through the magnetic field, and heating. Aims: This paper aims to investigate the differences between Doppler velocities of calcium ions and neutral hydrogen in a solar prominence to look for velocity differences between the neutral and ionized species. Methods: We simultaneously observed spectra of a prominence over an active region in H I 397 nm, H I 434 nm, Ca II 397 nm, and Ca II 854 nm using a high dispersion spectrograph of the Domeless Solar Telescope at Hida observatory. We compared the Doppler velocities, derived from the shift of the peak of the spectral lines presumably emitted from optically-thin plasma. Results: There are instances when the difference in velocities between neutral atoms and ions is significant, for example 1433 events ( 3% of sets of compared profiles) with a difference in velocity between neutral hydrogen atoms and calcium ions greater than 3σ of the measurement error. However, we also found significant differences between the Doppler velocities of two spectral lines emitted from the same species, and the probability density functions of velocity difference between the same species is not significantly different from those between neutral atoms and ions. Conclusions: We interpreted the difference of Doppler velocities as being a result of the motions of different components in the prominence along the line of sight, rather than the decoupling of neutral atoms from plasma. The movie attached to Fig. 1 is available at http://www.aanda.org

Dust dynamics and diagnostic applications in quasi-neutral plasmas and magnetic fusion

NASA Astrophysics Data System (ADS)

Wang, Zhehui; Ticos, Catalin M.; Si, Jiahe; Delzanno, Gian Luca; Lapenta, Gianni; Wurden, Glen

2007-11-01

Little is known about dust dynamics in highly ionized quasi-neutral plasmas with ca. 1.0 e+20 per cubic meter density and ion temperature at a few eV and above, including in magnetic fusion. For example, dust motion in fusion, better known as UFO's, has been observed since 1980's but not explained. Solid understanding of dust dynamics is also important to International Thermonuclear Experimental Reactor (ITER) because of concerns about safety and dust contamination of fusion core. Compared with well studied strongly-coupled dusty plasma regime, new physics may arise in the higher density quasi-neutral plasma regime because of at least four orders of magnitude higher density and two orders of magnitude hotter ion temperature. Our recent laboratory experiments showed that plasma-flow drag force dominates over other forces in a quasi-neutral flowing plasma. In contrast, delicate balance among different forces in dusty plasma has led to many unique phenomena, in particular, the formation of dust crystal. Based on our experiments, we argue that 1) dust crystal will not form in the highly ionized plasmas with flows; 2) the UFO's are moving dust dragged by plasma flows; 3) dust can be used to measure plasma flow. Two diagnostic applications using dust for laboratory quasi-neutral plasmas and magnetic fusion will also be presented.

Studies of Ion Beam Charge Neutralization by Ferroelectric Plasma Sources

NASA Astrophysics Data System (ADS)

Stepanov, A.; Gilson, E. P.; Grisham, L.; Davidson, R. C.

2013-10-01

Space-charge forces limit the possible transverse compression of high perveance ion beams that are used in ion-beam-driven high energy density physics applications; the minimum radius to which a beam can be focused is an increasing function of perveance. The limit can be overcome if a plasma is introduced in the beam path between the focusing element and the target in order to neutralize the space charge of the beam. This concept has been implemented on the Neutralized Drift Compression eXperiment (NDCX) at LBNL using Ferroelectric Plasma Sources (FEPS). In our experiment at PPPL, we propagate a perveance-dominated ion beam through a FEPS to study the effect of the neutralizing plasma on the beam envelope and its evolution in time. A 30-60 keV space-charge-dominated Argon beam is focused with an Einzel lens into a FEPS located at the beam waist. The beam is intercepted downstream from the FEPS by a movable Faraday cup that provides time-resolved 2D current density profiles of the beam spot on target. We report results on: (a) dependence of charge neutralization on FEPS plasma density; (b) effects on beam emittance, and (c) time evolution of the beam envelope after the FEPS pulse. Research supported by the U.S. Department of Energy.

HDP for the Neutralized pH Value Control in the Clarifying Process of Sugar Cane Juice

NASA Astrophysics Data System (ADS)

Lin, Xiaofeng; Yang, Jiaran

2009-05-01

Neutralizing pH value of sugar cane juice is the important craft in the control process in the clarifying process of sugar cane juice, which is the important factor to influence output and the quality of white sugar. On the one hand, it is an important content to control the neutralized pH value within a required range, which has the vital significance for acquiring high quality purified juice, reducing energy consumption and raising sucrose recovery. On the other hand, it is a complicated physical-chemistry process, which has the characteristics of strong non-linearity, time-varying, large time-delay, and multi-input. Therefore, there has not been a very good solution to control the neutralized pH value. Firstly, in this chapter, a neural network model for the clarifying process of sugar juice is established based on gathering 1200 groups of real-time sample data in a sugar factory. Then, the HDP (Heuristic Dynamic Programming) method is used to optimize and control the neutralized pH value in the clarifying process of sugar juice. Simulation results indicate that this method has good control effect. This will build a good foundation for stabilizing the clarifying process and enhancing the quality of the purified juice and lastly enhancing the quality of white sugar.

Ferroelectric Plasma Sources for Ion Beam Neutralization

NASA Astrophysics Data System (ADS)

Stepanov, A.; Gilson, E. P.; Grisham, L. R.; Davidson, R. C.

2014-10-01

A 40 keV Ar+ beam with a dimensionless perveance of 4 ×10-4 is propagated through a Ferroelectric Plasma Source (FEPS) to determine the effects of charge neutralization on the transverse beam profile. Neutralization is established 5 μs after the FEPS is triggered, and lasts between 10 and 35 μs. When the beam is fully neutralized, the profile has a Gaussian shape with a half-angle divergence of 0.87°, which is attributed to ion optics. The effects of the resistance and capacitance in the pulser circuit on the FEPS discharge are studied. The electron current emitted by the FEPS is calculated from measurements of the forward and return currents in the circuit. Electron emission typically begins 0.5 μs after the driving pulse, lasting for tens of μs, which is similar to the duration of ion beam neutralization. The total emitted charge does not depend significantly on the resistance, but depends strongly on the storage capacitance. Lowering the capacitance from 141 nF to 47 nF results in a near-complete shut-off of charge emission, although the amplitude of the applied voltage pulse is as high as when high-density plasma is produced. Overall, the data suggest that ferroelectric effects are significant in the physics of the FEPS discharge.

Exchanging physically effective neutral detergent fiber does not affect chewing activity and performance of late-lactation dairy cows fed corn and sugarcane silages.

PubMed

Sá Neto, A; Bispo, A W; Junges, D; Bercht, A K; Zopollatto, M; Daniel, J L P; Nussio, L G

2014-11-01

The objective of this study was to determine whether replacing the physically effective neutral detergent fiber (peNDF) of corn silage with sugarcane silage peNDF would affect performance in dairy cows. Twenty-four late-lactation Holstein cows were assigned to eight 3 × 3 Latin squares with 21-d periods. The dietary treatments were (1) 25% peNDF of corn silage, (2) 25% peNDF of sugarcane silage, and (3) 12.5% peNDF of corn silage + 12.5% peNDF of sugarcane silage. The physical effectiveness factors (pef) were assumed to be 1 for corn silage and 1.2 for sugarcane silage, as measured previously by bioassay. Thus, peNDF was calculated as neutral detergent fiber (NDF) × pef. The concentrate ingredients were finely ground corn, soybean meal, pelleted citrus pulp, and mineral-vitamin premix. Dry matter intake (22.5 ± 0.63 kg/d), 3.5% fat-corrected milk yield (28.8 ± 1.13 kg/d), milk composition (fat, protein, lactose, urea, casein, free fatty acids, and somatic cell count), and blood metabolites (glucose, insulin, and nonesterified fatty acids) were unaffected by the treatments. The time spent eating, ruminating, or chewing was also similar among the diets, as was particle-sorting behavior. By contrast, chewing per kilogram of forage NDF intake was higher for the sugarcane silage (137 min/kg) than the corn silage diet (116 min/kg), indicating the greater physical effectiveness of sugarcane fiber. Based on chewing behavior (min/d), the estimated pef of sugarcane silage NDF were 1.28 in the corn silage plus sugarcane silage diet and 1.29 in the sugarcane silage diet. Formulating dairy rations of equal peNDF content allows similar performance if corn and sugarcane silages are exchanged. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Mothers' physical interventions in toddler play in a low-income, African American sample.

PubMed

Ispa, Jean M; Claire Cook, J; Harmeyer, Erin; Rudy, Duane

2015-11-01

This mixed method study examined 28 low-income African American mothers' physical interventions in their 14-month-old toddlers' play. Inductive methods were used to identify six physical intervention behaviors, the affect accompanying physical interventions, and apparent reasons for intervening. Nonparametric statistical analyses determined that toddlers experienced physical intervention largely in the context of positive maternal affect. Mothers of boys expressed highly positive affect while physically intervening more than mothers of girls. Most physically intervening acts seemed to be motivated by maternal intent to show or tell children how to play or to correct play deemed incorrect. Neutral affect was the most common toddler affect type following physical intervention, but boys were more likely than girls to be upset immediately after physical interventions. Physical interventions intended to protect health and safety seemed the least likely to elicit toddler upset. Copyright © 2015 Elsevier Inc. All rights reserved.

Does the sight of physical threat induce a tactile processing bias? Modality-specific attentional facilitation induced by viewing threatening pictures.

PubMed

Van Damme, Stefaan; Gallace, Alberto; Spence, Charles; Crombez, Geert; Moseley, G Lorimer

2009-02-09

Threatening stimuli are thought to bias spatial attention toward the location from which the threat is presented. Although this effect is well-established in the visual domain, little is known regarding whether tactile attention is similarly affected by threatening pictures. We hypothesised that tactile attention might be more affected by cues implying physical threat to a person's bodily tissues than by cues implying general threat. In the present study, participants made temporal order judgments (TOJs) concerning which of a pair of tactile (or auditory) stimuli, one presented to either hand, at a range of inter-stimulus intervals, had been presented first. A picture (showing physical threat, general threat, or no threat) was presented in front of one or the other hand shortly before the tactile stimuli. The results revealed that tactile attention was biased toward the side on which the picture was presented, and that this effect was significantly larger for physical threat pictures than for general threat or neutral pictures. By contrast, the bias in auditory attention toward the side of the picture was significantly larger for general threat pictures than for physical threat pictures or neutral pictures. These findings therefore demonstrate a modality-specific effect of physically threatening cues on the processing of tactile stimuli, and of generally threatening cues on auditory information processing. These results demonstrate that the processing of tactile information from the body part closest to the threatening stimulus is prioritized over tactile information from elsewhere on the body.

Models of Solar Wind Structures and Their Interaction with the Earth's Space Environment

NASA Astrophysics Data System (ADS)

Watermann, J.; Wintoft, P.; Sanahuja, B.; Saiz, E.; Poedts, S.; Palmroth, M.; Milillo, A.; Metallinou, F.-A.; Jacobs, C.; Ganushkina, N. Y.; Daglis, I. A.; Cid, C.; Cerrato, Y.; Balasis, G.; Aylward, A. D.; Aran, A.

2009-11-01

The discipline of “Space Weather” is built on the scientific foundation of solar-terrestrial physics but with a strong orientation toward applied research. Models describing the solar-terrestrial environment are therefore at the heart of this discipline, for both physical understanding of the processes involved and establishing predictive capabilities of the consequences of these processes. Depending on the requirements, purely physical models, semi-empirical or empirical models are considered to be the most appropriate. This review focuses on the interaction of solar wind disturbances with geospace. We cover interplanetary space, the Earth’s magnetosphere (with the exception of radiation belt physics), the ionosphere (with the exception of radio science), the neutral atmosphere and the ground (via electromagnetic induction fields). Space weather relevant state-of-the-art physical and semi-empirical models of the various regions are reviewed. They include models for interplanetary space, its quiet state and the evolution of recurrent and transient solar perturbations (corotating interaction regions, coronal mass ejections, their interplanetary remnants, and solar energetic particle fluxes). Models of coupled large-scale solar wind-magnetosphere-ionosphere processes (global magnetohydrodynamic descriptions) and of inner magnetosphere processes (ring current dynamics) are discussed. Achievements in modeling the coupling between magnetospheric processes and the neutral and ionized upper and middle atmospheres are described. Finally we mention efforts to compile comprehensive and flexible models from selections of existing modules applicable to particular regions and conditions in interplanetary space and geospace.

Physical Conditions in Shocked Interstellar Gas Interacting with the Supernova Remnant IC 443

NASA Astrophysics Data System (ADS)

Ritchey, Adam M.; Federman, Steven Robert; Jenkins, Edward B.; Caprioli, Damiano; Wallerstein, George

2018-06-01

We present the results of a detailed investigation into the physical conditions in interstellar material interacting with the supernova remnant IC 443. Our analysis is based on an examination of high-resolution HST/STIS spectra of two stars probing predominantly neutral gas located both ahead of and behind the supernova shock front. The pre-shock neutral gas is characterized by densities and temperatures typical of diffuse interstellar clouds, while the post-shock material exhibits a range of more extreme physical conditions, including high temperatures (>104 K) in some cases, which may require a sudden heating event to explain. The ionization level is enhanced in the high-temperature post-shock material, which could be the result of enhanced radiation from shocks or from an increase in cosmic-ray ionization. The gas-phase abundances of refractory elements are also enhanced in the high-pressure gas, suggesting efficient destruction of dust grains by shock sputtering. Observations of highly-ionized species at very high velocity indicate a post-shock temperature of 107 K for the hot X-ray emitting plasma of the remnant’s interior, in agreement with studies of thermal X-ray emission from IC 443.

What measurements of neutrino neutral current events can reveal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gandhi, Raj; Kayser, Boris; Prakash, Suprabh

Here, we show that neutral current (NC) measurements at neutrino detectors can play a valuable role in the search for new physics. Such measurements have certain intrinsic features and advantages that can fruitfully be combined with the usual well-studied charged lepton detection channels in order to probe the presence of new interactions or new light states. In addition to the fact that NC events are immune to uncertainties in standard model neutrino mixing and mass parameters, they can have small matter effects and superior rates since all three flavours participate. We also show, as a general feature, that NC measurementsmore » provide access to different combinations of CP phases and mixing parameters compared to CC measurements at both long and short baseline experiments. Using the Deep Underground Neutrino Experiment (DUNE) as an illustrative setting, we demonstrate the capability of NC measurements to break degeneracies arising in CC measurements, allowing us, in principle, to distinguish between new physics that violates three flavour unitarity and that which does not. Finally, we show that NC measurements can enable us to restrict new physics parameters that are not easily constrained by CC measurements.« less

What measurements of neutrino neutral current events can reveal

DOE PAGES

Gandhi, Raj; Kayser, Boris; Prakash, Suprabh; ...

2017-11-29

Here, we show that neutral current (NC) measurements at neutrino detectors can play a valuable role in the search for new physics. Such measurements have certain intrinsic features and advantages that can fruitfully be combined with the usual well-studied charged lepton detection channels in order to probe the presence of new interactions or new light states. In addition to the fact that NC events are immune to uncertainties in standard model neutrino mixing and mass parameters, they can have small matter effects and superior rates since all three flavours participate. We also show, as a general feature, that NC measurementsmore » provide access to different combinations of CP phases and mixing parameters compared to CC measurements at both long and short baseline experiments. Using the Deep Underground Neutrino Experiment (DUNE) as an illustrative setting, we demonstrate the capability of NC measurements to break degeneracies arising in CC measurements, allowing us, in principle, to distinguish between new physics that violates three flavour unitarity and that which does not. Finally, we show that NC measurements can enable us to restrict new physics parameters that are not easily constrained by CC measurements.« less

21cm Absorption Line Zeeman Observations And Modeling Of Physical Conditions In M16

NASA Astrophysics Data System (ADS)

Kiuchi, Furea; Brogan, C.; Troland, T.

2011-01-01

We present detailed 21 cm HI absorption line observations of M16 using the Very Large Array. The M16 "pillars of creation" are classic examples of the interaction of ISM with radiation from young, hot stars. Magnetic fields can affect these interactions, the 21 cm Zeeman effect reveals magnetic field strengths in the Photodissociation regions associated with the pillars. The present results yield a 3-sigma upper limit upon the line-of-sight magnetic field of about 300 microgauss. This limit is consistent with a total field strength of 500 microgauss, required in the molecular gas if magnetic energies and turbulent energies in the pillars are in equipartition. Most likely, magnetic fields do not play a dominant role in the dynamics of the M16 pillars. Another goal of this study is to determine the distribution of cold HI in the M16 region and to model the physical conditions in the neutral gas in the pillars. We used the spectral synthesis code Cloudy 08.00 for this purpose. We adopted the results of a published Cloudy HII region model and extended this model into the neutral gas to derive physical conditions therein.

Destructive physical analysis of hollow cathodes from the Deep Space 1 Flight spare ion engine 30,000 hr life test

NASA Technical Reports Server (NTRS)

Sengupta, Anita

2005-01-01

Destructive physical analysis of the discharge and neutralizer hollow cathode assemblies from the Deep Space 1 Flight Spare 30,000 Hr life test was performed to characterize physical and chemical evidence of operationally induced effects after 30,372 hours of operation with beam extraction. Post-test inspection of the discharge-cathode assembly was subdivided into detailed analyses at the subcomponent level. Detailed materials analysis and optical inspection of the insert, orifice plate, cathode tube, heater, keeper assembly, insulator, and low-voltage propellant isolator were performed. Energy dispersive X-ray (EDX) and scanning electron microscopy (SEW analyses were used to determine the extent and composition of regions of net deposition and erosion of both the discharge and neutralizer inserts. A comparative approach with an un-operated 4:1:1 insert was used to determine the extent of impregnate material depletion as a function of depth from the ID surface and axial position from the orifice plate. Analysis results are compared and contrasted with those obtained from similar analyses on components from shorter term tests, and provide insight regarding the prospect for successful longer-term operation consistent with SOA ion engine program life objectives at NASA.

Non-neutralized Electric Currents in Solar Active Regions and Flare Productivity

NASA Astrophysics Data System (ADS)

Kontogiannis, Ioannis; Georgoulis, Manolis K.; Park, Sung-Hong; Guerra, Jordan A.

2017-11-01

We explore the association of non-neutralized currents with solar flare occurrence in a sizable sample of observations, aiming to show the potential of such currents in solar flare prediction. We used the high-quality vector magnetograms that are regularly produced by the Helioseismic Magnetic Imager, and more specifically, the Space weather HMI Active Region Patches (SHARP). Through a newly established method that incorporates detailed error analysis, we calculated the non-neutralized currents contained in active regions (AR). Two predictors were produced, namely the total and the maximum unsigned non-neutralized current. Both were tested in AR time-series and a representative sample of point-in-time observations during the interval 2012 - 2016. The average values of non-neutralized currents in flaring active regions are higher by more than an order of magnitude than in non-flaring regions and correlate very well with the corresponding flare index. The temporal evolution of these parameters appears to be connected to physical processes, such as flux emergence and/or magnetic polarity inversion line formation, that are associated with increased solar flare activity. Using Bayesian inference of flaring probabilities, we show that the total unsigned non-neutralized current significantly outperforms the total unsigned magnetic flux and other well-established current-related predictors. It therefore shows good prospects for inclusion in an operational flare-forecasting service. We plan to use the new predictor in the framework of the FLARECAST project along with other highly performing predictors.

Long-range attraction of an ultrarelativistic electron beam by a column of neutral plasma

DOE PAGES

Adli, Erik; Lindstrom, C. A.; Allen, J.; ...

2016-10-12

Here, we report on the experimental observation of the attraction of a beam of ultrarelativistic electrons towards a column of neutral plasma. In experiments performed at the FACET test facility at SLAC we observe that an electron beam moving parallel to a neutral plasma column, at an initial distance of many plasma column radii, is attracted into the column. Once the beam enters the plasma it drives a plasma wake similar to that of an electron beam entering the plasma column head-on. A simple analytical model is developed in order to capture the essential physics of the attractive force. Themore » attraction is further studied by 3D particle-in-cell numerical simulations. The results are an important step towards better understanding of particle beam–plasma interactions in general and plasma wakefield accelerator technology in particular.« less

Does modulation of selective attention to features reflect enhancement or suppression of neural activity?

PubMed

Daffner, Kirk R; Zhuravleva, Tatyana Y; Sun, Xue; Tarbi, Elise C; Haring, Anna E; Rentz, Dorene M; Holcomb, Phillip J

2012-02-01

Numerous studies have demonstrated that selective attention to color is associated with a larger neural response under attend than ignore conditions, but have not addressed whether this difference reflects enhanced activity under attend or suppressed activity under ignore. In this study, a color-neutral condition was included, which presented stimuli physically identical to those under attend and ignore conditions, but in which color was not task relevant. Attention to color did not modulate the early sensory-evoked P1 and N1 components. Traditional ERP markers of early selection (the anterior Selection Positivity and posterior Selection Negativity) did not differ between the attend and neutral conditions, arguing against a mechanism of enhanced activity. However, there were markedly reduced responses under the ignore relative to the neutral condition, consistent with the view that early selection mechanisms reflect suppression of neural activity under the ignore condition. Copyright © 2011 Elsevier B.V. All rights reserved.

Long-range attraction of an ultrarelativistic electron beam by a column of neutral plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adli, Erik; Lindstrom, C. A.; Allen, J.

Here, we report on the experimental observation of the attraction of a beam of ultrarelativistic electrons towards a column of neutral plasma. In experiments performed at the FACET test facility at SLAC we observe that an electron beam moving parallel to a neutral plasma column, at an initial distance of many plasma column radii, is attracted into the column. Once the beam enters the plasma it drives a plasma wake similar to that of an electron beam entering the plasma column head-on. A simple analytical model is developed in order to capture the essential physics of the attractive force. Themore » attraction is further studied by 3D particle-in-cell numerical simulations. The results are an important step towards better understanding of particle beam–plasma interactions in general and plasma wakefield accelerator technology in particular.« less

Characterization of a 5-eV neutral atomic oxygen beam facility

NASA Technical Reports Server (NTRS)

Vaughn, J. A.; Linton, R. C.; Carruth, M. R., Jr.; Whitaker, A. F.; Cuthbertson, J. W.; Langer, W. D.; Motley, R. W.

1991-01-01

An experimental effort to characterize an existing 5-eV neutral atomic oxygen beam facility being developed at Princeton Plasma Physics Laboratory is described. This characterization effort includes atomic oxygen flux and flux distribution measurements using a catalytic probe, energy determination using a commercially designed quadrupole mass spectrometer (QMS), and the exposure of oxygen-sensitive materials in this beam facility. Also, comparisons were drawn between the reaction efficiencies of materials exposed in plasma ashers, and the reaction efficiencies previously estimated from space flight experiments. The results of this study show that the beam facility is capable of producing a directional beam of neutral atomic oxygen atoms with the needed flux and energy to simulate low Earth orbit (LEO) conditions for real time accelerated testing. The flux distribution in this facility is uniform to +/- 6 percent of the peak flux over a beam diameter of 6 cm.

A comparative study of capacitively coupled HBr/He, HBr/Ar plasmas for etching applications: Numerical investigation by fluid model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gul, Banat, E-mail: banatgul@gmail.com; Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp; Aman-ur-Rehman, E-mail: amansadiq@gmail.com

Fluid model has been applied to perform a comparative study of hydrogen bromide (HBr)/He and HBr/Ar capacitively coupled plasma discharges that are being used for anisotropic etching process. This model has been used to identify the most dominant species in HBr based plasmas. Our simulation results show that the neutral species like H and Br, which are the key player in chemical etching, have bell shape distribution, while ions like HBr{sup +}, Br{sup +}, which play a dominant rule in the physical etching, have double humped distribution and show peaks near electrodes. It was found that the dilution of HBrmore » by Ar and/or He results in an increase in electron density and electron temperature, which results in more ionization and dissociation and hence higher densities of neutral and charged species can be achieved. The ratio of positive ion flux to the neutral flux increases with an increase in additive gas fraction. Compare to HBr/He plasma, the HBr/Ar plasma shows a maximum change in the ion density and flux and hence the etching rate can be considered in the ion-assisted and in the ion-flux etch regime in HBr/Ar discharge. The densities of electron and other dominant species in HBr/Ar plasma are higher than those of HBr/He plasma. The densities and fluxes of the active neutrals and positive ions for etching and subsequently chemical etching versus physical sputtering in HBr/Ar and HBr/He plasmas discharge can be controlled by tuning gas mixture ratio and the desire etching can be achieved.« less

Ultracold neutral plasmas

NASA Astrophysics Data System (ADS)

Lyon, M.; Rolston, S. L.

2017-01-01

By photoionizing samples of laser-cooled atoms with laser light tuned just above the ionization limit, plasmas can be created with electron and ion temperatures below 10 K. These ultracold neutral plasmas have extended the temperature bounds of plasma physics by two orders of magnitude. Table-top experiments, using many of the tools from atomic physics, allow for the study of plasma phenomena in this new regime with independent control over the density and temperature of the plasma through the excitation process. Characteristic of these systems is an inhomogeneous density profile, inherited from the density distribution of the laser-cooled neutral atom sample. Most work has dealt with unconfined plasmas in vacuum, which expand outward at velocities of order 100 m/s, governed by electron pressure, and with lifetimes of order 100 μs, limited by stray electric fields. Using detection of charged particles and optical detection techniques, a wide variety of properties and phenomena have been observed, including expansion dynamics, collective excitations in both the electrons and ions, and collisional properties. Through three-body recombination collisions, the plasmas rapidly form Rydberg atoms, and clouds of cold Rydberg atoms have been observed to spontaneously avalanche ionize to form plasmas. Of particular interest is the possibility of the formation of strongly coupled plasmas, where Coulomb forces dominate thermal motion and correlations become important. The strongest impediment to strong coupling is disorder-induced heating, a process in which Coulomb energy from an initially disordered sample is converted into thermal energy. This restricts electrons to a weakly coupled regime and leaves the ions barely within the strongly coupled regime. This review will give an overview of the field of ultracold neutral plasmas, from its inception in 1999 to current work, including efforts to increase strong coupling and effects on plasma properties due to strong coupling.

Neutralizer Hollow Cathode Simulations and Comparisons with Ground Test Data

NASA Technical Reports Server (NTRS)

Mikellides, Ioannis G.; Snyder, John S.; Goebel, Dan M.; Katz, Ira; Herman, Daniel A.

2009-01-01

The fidelity of electric propulsion physics-based models depends largely on the validity of their predictions over a range of operating conditions and geometries. In general, increased complexity of the physics requires more extensive comparisons with laboratory data to identify the region(s) that lie outside the validity of the model assumptions and to quantify the uncertainties within its range of application. This paper presents numerical simulations of neutralizer hollow cathodes at various operating conditions and orifice sizes. The simulations were performed using a two-dimensional axisymmetric model that solves numerically a relatively extensive system of conservation laws for the partially ionized gas in these devices. A summary of the comparisons between simulation results and Langmuir probe measurements is provided. The model has also been employed to provide insight into recent ground test observations of the neutralizer cathode in NEXT. It is found that a likely cause of the observed keeper voltage drop is cathode orifice erosion. However, due to the small magnitude of this change, is approx. 0.5 V (less than 5% of the beginning-of-life value) over 10 khrs, and in light of the large uncertainties of the cathode material sputtering yield at low ion energies, other causes cannot be excluded. Preliminary simulations to understand transition to plume mode suggest that in the range of 3-5 sccm the existing 2-D model reproduces fairly well the rise of the keeper voltage in the NEXT neutralizer as observed in the laboratory. At lower flow rates the simulation produces oscillations in the keeper current and voltage that require prohibitively small time-steps to resolve with the existing algorithms.

Estimating Neutral Atmosphere Drivers using a Physical Model

DTIC Science & Technology

2009-03-30

Araujo-Pradere, M. Fedrizzi, 2007, Memory effects in the ionosphere storm response. EGU General Assembly , Vienna, Austria Codrescu, M., T.J. Fuller...Strickland, D, 2007: Application of thermospheric general circulation models for space weather operations. J. Adv. Space Res., edited by Schmidtke

Untitled Document

Science.gov Websites

charged tracks or associated with photons or neutral hadrons. Hardware effort: A Digital Hadron fine segmentation, the energy resolution for single hadrons is preserved with a simple digital readout Physics Division Digital Hadron Calorimeter with RPCs (US effort) CALICE Collaboration American Linear

Investigation of the DSMC Approach for Ion/neutral Species in Modeling Low Pressure Plasma Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng Hao; Li, Z.; Levin, D.

2011-05-20

Low pressure plasma reactors are important tools for ionized metal physical vapor deposition (IMPVD), a semiconductor plasma processing technology that is increasingly being applied to deposit Cu seed layers on semiconductor surfaces of trenches and vias with the high aspect ratio (e.g., >5:1). A large fraction of ionized atoms produced by the IMPVD process leads to an anisotropic deposition flux towards the substrate, a feature which is critical for attaining a void-free and uniform fill. Modeling such devices is challenging due to their high plasma density, reactive environment, but low gas pressure. A modular code developed by the Computational Opticalmore » and Discharge Physics Group, the Hybrid Plasma Equipment Model (HPEM), has been successfully applied to the numerical investigations of IMPVD by modeling a hollow cathode magnetron (HCM) device. However, as the development of semiconductor devices progresses towards the lower pressure regime (e.g., <5 mTorr), the breakdown of the continuum assumption limits the application of the fluid model in HPEM and suggests the incorporation of the kinetic method, such as the direct simulation Monte Carlo (DSMC), in the plasma simulation.The DSMC method, which solves the Boltzmann equation of transport, has been successfully applied in modeling micro-fluidic flows in MEMS devices with low Reynolds numbers, a feature shared with the HCM. Modeling of the basic physical and chemical processes for ion/neutral species in plasma have been developed and implemented in DSMC, which include ion particle motion due to the Lorentz force, electron impact reactions, charge exchange reactions, and charge recombination at the surface. The heating of neutrals due to collisions with ions and the heating of ions due to the electrostatic field will be shown to be captured by the DSMC simulations. In this work, DSMC calculations were coupled with the modules from HPEM so that the plasma can be self-consistently solved. Differences in the Ar results, the dominant species in the reactor, produced by the DSMC-HPEM coupled simulation will be shown in comparison with the original HPEM results. The effects of the DSMC calculations for ion/neutral species on HPEM plasma simulation will be further analyzed.« less

Exercise in children with joint hypermobility syndrome and knee pain: a randomised controlled trial comparing exercise into hypermobile versus neutral knee extension

PubMed Central

2013-01-01

Background Knee pain in children with Joint Hypermobility Syndrome (JHS) is traditionally managed with exercise, however the supporting evidence for this is scarce. No trial has previously examined whether exercising to neutral or into the hypermobile range affects outcomes. This study aimed to (i) determine if a physiotherapist-prescribed exercise programme focused on knee joint strength and control is effective in reducing knee pain in children with JHS compared to no treatment, and (ii) whether the range in which these exercises are performed affects outcomes. Methods A prospective, parallel-group, randomised controlled trial conducted in a tertiary hospital in Sydney, Australia compared an 8 week exercise programme performed into either the full hypermobile range or only to neutral knee extension, following a minimum 2 week baseline period without treatment. Randomisation was computer-generated, with allocation concealed by sequentially numbered opaque sealed envelopes. Knee pain was the primary outcome. Quality of life, thigh muscle strength, and function were also measured at (i) initial assessment, (ii) following the baseline period and (iii) post treatment. Assessors were blinded to the participants’ treatment allocation and participants blinded to the difference in the treatments. Results Children with JHS and knee pain (n=26) aged 7-16 years were randomly assigned to the hypermobile (n=12) or neutral (n=14) treatment group. Significant improvements in child-reported maximal knee pain were found following treatment, regardless of group allocation with a mean 14.5 mm reduction on the visual analogue scale (95% CI 5.2 – 23.8 mm, p=0.003). Significant differences between treatment groups were noted for parent-reported overall psychosocial health (p=0.009), specifically self-esteem (p=0.034), mental health (p=0.001) and behaviour (p=0.019), in favour of exercising into the hypermobile range (n=11) compared to neutral only (n=14). Conversely, parent-reported overall physical health significantly favoured exercising only to neutral (p=0.037). No other differences were found between groups and no adverse events occurred. Conclusions Parents perceive improved child psychosocial health when children exercise into the hypermobile range, while exercising to neutral only is perceived to favour the child’s physical health. A physiotherapist prescribed, supervised, individualised and progressed exercise programme effectively reduces knee pain in children with JHS. Trial registration Australia & New Zealand Clinical Trials Registry; ACTRN12606000109505. PMID:23941143

Steady-State Ion Beam Modeling with MICHELLE

NASA Astrophysics Data System (ADS)

Petillo, John

2003-10-01

There is a need to efficiently model ion beam physics for ion implantation, chemical vapor deposition, and ion thrusters. Common to all is the need for three-dimensional (3D) simulation of volumetric ion sources, ion acceleration, and optics, with the ability to model charge exchange of the ion beam with a background neutral gas. The two pieces of physics stand out as significant are the modeling of the volumetric source and charge exchange. In the MICHELLE code, the method for modeling the plasma sheath in ion sources assumes that the electron distribution function is a Maxwellian function of electrostatic potential over electron temperature. Charge exchange is the process by which a neutral background gas with a "fast" charged particle streaming through exchanges its electron with the charged particle. An efficient method for capturing this is essential, and the model presented is based on semi-empirical collision cross section functions. This appears to be the first steady-state 3D algorithm of its type to contain multiple generations of charge exchange, work with multiple species and multiple charge state beam/source particles simultaneously, take into account the self-consistent space charge effects, and track the subsequent fast neutral particles. The solution used by MICHELLE is to combine finite element analysis with particle-in-cell (PIC) methods. The basic physics model is based on the equilibrium steady-state application of the electrostatic particle-in-cell (PIC) approximation employing a conformal computational mesh. The foundation stems from the same basic model introduced in codes such as EGUN. Here, Poisson's equation is used to self-consistently include the effects of space charge on the fields, and the relativistic Lorentz equation is used to integrate the particle trajectories through those fields. The presentation will consider the complexity of modeling ion thrusters.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedman, A; Barnard, J J; Briggs, R J

The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL), a collaboration of LBNL, LLNL, and PPPL, has achieved 60-fold pulse compression of ion beams on the Neutralized Drift Compression eXperiment (NDCX) at LBNL. In NDCX, a ramped voltage pulse from an induction cell imparts a velocity 'tilt' to the beam; the beam's tail then catches up with its head in a plasma environment that provides neutralization. The HIFS-VNL's mission is to carry out studies of warm dense matter (WDM) physics using ion beams as the energy source; an emerging thrust is basic target physics for heavy ion-driven inertial fusion energymore » (IFE). These goals require an improved platform, labeled NDCX-II. Development of NDCX-II at modest cost was recently enabled by the availability of induction cells and associated hardware from the decommissioned advanced test accelerator (ATA) facility at LLNL. Our initial physics design concept accelerates an {approx} 30 nC pulse of Li{sup +} ions to {approx} 3 MeV, then compresses it to {approx} 1 ns while focusing it onto a mm-scale spot. It uses the ATA cells themselves (with waveforms shaped by passive circuits) to impart the final velocity tilt; smart pulsers provide small corrections. The ATA accelerated electrons; acceleration of non-relativistic ions involves more complex beam dynamics both transversely and longitudinally. We are using an interactive one-dimensional kinetic simulation model and multidimensional Warp-code simulations to develop the NDCX-II accelerator section. Both LSP and Warp codes are being applied to the beam dynamics in the neutralized drift and final focus regions, and the plasma injection process. The status of this effort is described.« less

The Effects of Neutral Gas Release on Vehicle Charging: Experiment and Theory

NASA Astrophysics Data System (ADS)

Walker, D. N.; Amatucci, W. E.; Bowles, J. H.; Fernsler, R. F.; Siefring, C. L.; Antoniades, J. A.; Keskinen, M. J.

1998-11-01

This paper describes an experimental and theoretical research effort related to the mitigation of spacecraft charging by Neutral Gas Release (NGR). The Space Power Experiments Aboard Rockets programs (SPEAR I and III) [Mandel et al., 1998; Berg et al., 1995] and other earlier efforts have demonstrated that NGR is an effective method of controlling discharges in space. The laboratory experimentswere conducted in the large volume Space Physics Simulation Chamber (SPSC) at the Naval Research Laboratory (NRL). A realistic near-earth space environment can be simulated in this device for whichminimumscalingneeds to be performedtorelate the data to space plasma regimes. This environment is similar to that encountered by LEO spacecraft, e.g., the Space Station, Shuttle, and high inclination satellites. The experimental arrangement consists of an aluminum cylinder which can be biased to high negative voltage (0.4 kV

Development of a 1-m plasma source for heavy ion beam charge neutralization

NASA Astrophysics Data System (ADS)

Efthimion, Philip C.; Gilson, Erik P.; Grisham, Larry; Davidson, Ronald C.; Yu, Simon; Waldron, William; Grant Logan, B.

2005-05-01

Highly ionized plasmas are being employed as a medium for charge neutralizing heavy ion beams in order to focus to a small spot size. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length ˜0.1-1 m would be suitable for achieving a high level of charge neutralization. A radio frequency (RF) source was constructed at the Princeton Plasma Physics Laboratory (PPPL) in support of the joint Neutralized Transport Experiment (NTX) at the Lawrence Berkeley National Laboratory (LBNL) to study ion beam neutralization. Pulsing the source enabled operation at pressures ˜10 -6 Torr with plasma densities of 10 11 cm -3. Near 100% ionization was achieved. The plasma was 10 cm in length, but future experiments require a source 1 m long. The RF source does not easily scale to the length. Consequently, large-volume plasma sources based upon ferroelectric ceramics are being considered. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. The source will utilize the ferroelectric ceramic BaTiO 3 to form metal plasma. A 1 m long section of the drift tube inner surface of NTX will be covered with ceramic. A high voltage (˜1-5 kV) is applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. Plasma densities of 10 12 cm -3 and neutral pressures ˜10 -6 Torr are expected. A test stand to produce 20 cm long plasma is being constructed and will be tested before a 1 m long source is developed.

Search for new neutral gauge bosons with the CMS Experiment at the LHC

NASA Astrophysics Data System (ADS)

Lanyov, Alexander; Shmatov, Sergei; Zhizhin, Ilia

2018-04-01

A search for narrow resonances in dimuon invariant mass spectra has been performed using 13 fb-1 data obtained in 2016 from proton-proton collisions at √s = 13 TeV with the CMS experiment at the LHC. No evidence for physics beyond standard model is found. Limits on the production cross section and the masses of hypothetical particles that could appear in the scenarios of new physics have been set.

Quantum Computation and Simulation Using Neutral Fermionic Atoms

DTIC Science & Technology

2014-06-06

labeled n = 1) Efimov trimer crosses the three-atom scattering threshold. Working in the context of nuclear physics in the early 1970’s, Vitaly Efimov...permit the observation of anti-ferromagnetic ordering in the Hubbard model. (a) Papers published in peer-reviewed journals ( N /A for none) Enter List of...Physics, (06 2011): 0. doi: TOTAL: 7 Number of Papers published in peer-reviewed journals: (b) Papers published in non-peer-reviewed journals ( N /A for

Physical coldness enhances racial in-group bias in empathy: Electrophysiological evidence.

PubMed

Luo, Siyang; Han, Xiaochun; Du, Na; Han, Shihui

2017-05-03

Empathy for others' pain plays a key role in prosocial behavior and is influenced by intergroup relationships. Increasing evidence suggests greater empathy for racial in-group than out-group individuals' pain and the racial in-group bias undergoes sociocultural and biological influences. The present study further investigated whether and how physical environments influence racial in-group bias in empathy by testing the hypothesis that sensory experiences of physical coldness versus warmth enhance differential empathic neural responses to racial in-group vs. out-group individuals' suffering. We recorded event-related brain potentials to painful versus neutral expressions of same-race and other-race faces when participants held a cold or warm pack. We found that brain activity in the N2 (200-340ms) and P3 (400-600ms) time windows over the frontal/central region was positively shifted by painful (vs. neutral) expressions. Moreover, the N2/P3 empathic neural responses were significantly larger for same-race than other-race faces in the cold but not in the warm condition. Moreover, subjective ratings of different temperatures in the cold vs. warm conditions predicted larger changes of racial in-group bias in empathic neural responses in the N2 time window. Our findings suggest that sensory experiences of physical coldness can strengthen emotional resonance with same-race individuals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Entangling two transportable neutral atoms via local spin exchange.

PubMed

Kaufman, A M; Lester, B J; Foss-Feig, M; Wall, M L; Rey, A M; Regal, C A

2015-11-12

To advance quantum information science, physical systems are sought that meet the stringent requirements for creating and preserving quantum entanglement. In atomic physics, robust two-qubit entanglement is typically achieved by strong, long-range interactions in the form of either Coulomb interactions between ions or dipolar interactions between Rydberg atoms. Although such interactions allow fast quantum gates, the interacting atoms must overcome the associated coupling to the environment and cross-talk among qubits. Local interactions, such as those requiring substantial wavefunction overlap, can alleviate these detrimental effects; however, such interactions present a new challenge: to distribute entanglement, qubits must be transported, merged for interaction, and then isolated for storage and subsequent operations. Here we show how, using a mobile optical tweezer, it is possible to prepare and locally entangle two ultracold neutral atoms, and then separate them while preserving their entanglement. Ground-state neutral atom experiments have measured dynamics consistent with spin entanglement, and have detected entanglement with macroscopic observables; we are now able to demonstrate position-resolved two-particle coherence via application of a local gradient and parity measurements. This new entanglement-verification protocol could be applied to arbitrary spin-entangled states of spatially separated atoms. The local entangling operation is achieved via spin-exchange interactions, and quantum tunnelling is used to combine and separate atoms. These techniques provide a framework for dynamically entangling remote qubits via local operations within a large-scale quantum register.

Laboratory Studies of Thermal Energy Charge Transfer of Multiply Charged Ions in Astrophysical Plasmas

NASA Technical Reports Server (NTRS)

Kwong, Victor H. S.

2003-01-01

The laser ablation/ion storage facility at the UNLV Physics Department has been dedicated to the study of atomic and molecular processes in low temperature plasmas. Our program focuses on the charge transfer (electron capture) of multiply charged ions and neutrals important in astrophysics. The electron transfer reactions with atoms and molecules is crucial to the ionization condition of neutral rich photoionized plasmas. With the successful deployment of the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Chandra X-ray Observatory by NASA high resolution VUV and X-ray emission spectra fiom various astrophysical objects have been collected. These spectra will be analyzed to determine the source of the emission and the chemical and physical environment of the source. The proper interpretation of these spectra will require complete knowledge of all the atomic processes in these plasmas. In a neutral rich environment, charge transfer can be the dominant process. The rate coefficients need to be known accurately. We have also extended our charge transfer measurements to KeV region with a pulsed ion beam. The inclusion of this facility into our current program provides flexibility in extending the measurement to higher energies (KeV) if needed. This flexibility enables us to address issues of immediate interest to the astrophysical community as new observations are made by high resolution space based observatories.

Global Properties of the Heliospheric Termination Shock as inferred from Energetic Neutral Atoms measured by the Interstellar Boundary Explorer (IBEX)

NASA Astrophysics Data System (ADS)

Desai, Mihir; Heerikhuisen, Jacob; McComas, David; Pogorelov, Nikolai; Zank, Gary; Dayeh, Maher; Schwadron, Nathan; Allegrini, Frederic; Zirnstein, Eric

Energetic Neutral Atoms (ENAs) observed by the Interstellar Boundary Explorer (IBEX) provide powerful diagnostics about the origin of the progenitor ion populations and the physical mechanisms responsible for their production. Desai et al. (2012; 2013) combined and compared ENA spectra from the first three years of observations by the IBEX-Hi and -Lo ENA imagers along the lines-of-sights (LOS) from the inner heliosphere through to the locations of Voyager 1 and 2 with results from an updated physics-based model of the 3D heliosphere and its constituent ion populations. These results showed that (1) IBEX ENA fluxes and spectra above ˜0.7 keV measured along the LOS of the Voyagers are consistent with several models in which the parent pickup (PUI) populations originate in the inner heliosheath, and (2) a significant fraction of lower-energy ENAs between ˜0.1-0.5 keV may originate from interstellar neutral gas charge-exchanging with a non-thermalized (hot) population of PUIs in the outer heliosheath beyond the heliopause. We use these results and model the full sky IBEX-Hi energy spectra to probe the microphysical processes occurring in the inner heliospheath near the termination shock and then infer the global properties (e.g., latitudinal and longitudinal variations of the shock compression ratio) of the termination shock.

Microbead-based immunoassay using the outer membrane layer of Escherichia coli combined with autodisplayed Z-domains

NASA Astrophysics Data System (ADS)

Kim, Do-Hoon; Bong, Ji-Hong; Yoo, Gu; Chang, Seo-Yoon; Park, Min; Chang, Young Wook; Kang, Min-Jung; Jose, Joachim; Pyun, Jae-Chul

2016-01-01

The Z-domain has the potential to control the orientation of immobilized antibodies because of its binding affinity to the Fc regions of antibodies (IgGs). In this work, Z-domains were autodisplayed on the outer membrane (OM) of Escherichia coli. OM particles were isolated and coated onto microbeads with positive, neutral, or negative surface charges. Other conditions such as incubation time and initial OM concentration were also optimized for the OM coating to obtain maximum antibody-binding. Using three kinds of model proteins with different isoelectric points (pI), streptavidin (pI = 5, negative charge at pH 7), horseradish peroxidase (pI = 7, neutral charge at pH 7), and avidin (pI = 10, positive charge at pH 7), protein immobilization onto the microbeads was carried out through physical adsorption and electrostatic interactions. Using fluorescently labeled antibodies and fluorescence-activated cell sorting, it was determined that the neutral and the positively charged microbeads effectively bound antibodies while minimizing non-specific protein binding. The OM-coated microbeads with autodisplayed Z-domains were applied to C-reactive protein immunoassay. This immunoassay achieved 5-fold improved sensitivity compared to conventional immunoassay based on physical adsorption of antibodies at the cutoff concentration of medical diagnosis of inflammatory diseases (1000 ng/ml) and cardiovascular diseases (200 ng/ml).

Interstellar Matters: Neutral Hydrogen and the Galactic Magnetic Field

NASA Astrophysics Data System (ADS)

Verschuur, Gerrit; Schmelz, Joan T.; Asgari-Targhi asgari-Targhi, M.

2018-01-01

The physics of the interstellar medium was revolutionized by the observations of the Galactic Arecibo L-Band Feed Array (GALFA) HI survey done at the Arecibo Observatory. The high-resolution, high-sensitivity, high-dynamic- range images show complex, tangled, extended filaments, and reveal that the fabric of the neutral interstellar medium is deeply tied to the structure of the ambient magnetic field. This discovery prompts an obvious question – how exactly is the interstellar {\\it neutral} hydrogen being affected by the galactic magnetic field? We look into this question by examining a set of GALFA-HI data in great detail. We have chosen a long, straight filament in the southern galactic sky. This structure is both close by and isolated in velocity space. Gaussian analysis of profiles both along and across the filament reveal internal structure – braided strands that can be traced through the simplest part, but become tangled in more complex segments. These braids do not resemble in any way the old spherical HI clouds and rudimentary pressure balance models that were used to explain the pre-GALFA- HI interstellar medium. It is clear that these structures are created, constrained, and dominated by magnetic fields. Like many subfields of astronomy before it, e.g., physics of the solar coronal, extragalactic radio jets, and pulsar environment, scientists are confronted with observations that simply cannot be explained by simple hydrodynamics and are forced to consider magneto-hydrodynamics.

Rapid Dominance: Integrating Space into Today’s Air Operations Center

DTIC Science & Technology

2000-04-01

satellites themselves, data-processing nodes, and user equipment, which can be neutralized through physical operations—bombs on target or...Conflict Resolution Coursebook , Col Robert C. Owen, Jan­ uary 1999, 199. 9. USSPACECOM is now responsible for planning, coordinating, and executing

Active spectroscopic measurements using the ITER diagnostic system.

PubMed

Thomas, D M; Counsell, G; Johnson, D; Vasu, P; Zvonkov, A

2010-10-01

Active (beam-based) spectroscopic measurements are intended to provide a number of crucial parameters for the ITER device being built in Cadarache, France. These measurements include the determination of impurity ion temperatures, absolute densities, and velocity profiles, as well as the determination of the plasma current density profile. Because ITER will be the first experiment to study long timescale (∼1 h) fusion burn plasmas, of particular interest is the ability to study the profile of the thermalized helium ash resulting from the slowing down and confinement of the fusion alphas. These measurements will utilize both the 1 MeV heating neutral beams and a dedicated 100 keV hydrogen diagnostic neutral beam. A number of separate instruments are being designed and built by several of the ITER partners to meet the different spectroscopic measurement needs and to provide the maximum physics information. In this paper, we describe the planned measurements, the intended diagnostic ensemble, and we will discuss specific physics and engineering challenges for these measurements in ITER.

Multifrequency survey of the intergalactic cloud in the M96 group

NASA Technical Reports Server (NTRS)

Schneider, Stephen E.; Skrutskie, M. F.; Hacking, Perry B.; Young, Judith S.; Dickman, Robert L.

1989-01-01

The intergalactic cloud of neutral hydrogen in the M96 group are examined for signs of emission over a wide range of frequencies, from radio waves to X rays. Past or present stellar activity in the gas might have been expected to produce detectable visual infrared, CO, OH, or radio recombination-line emission. None was detected. The limits are used to study physical conditions in the intergalactic gas. In particular, B and V band limits on starlight and IRAS limits on the presence of dust strongly constrain the presence of stars or stellar by-products. However, given the uncertainties about physical conditions in the intergalactic environment, it is difficult to rule out entirely the presence of stellar-processed materials. Results of neutral hydrogen mapping from a large-scale survey of the intergalactic cloud and surrounding region are also presented. These observations confirm that the gas is confined to a large ringlike structure. The simplest interpretation remains that the intergalactic gas in Leo is primordial.

The GOL-NB program: further steps in multiple-mirror confinement research

NASA Astrophysics Data System (ADS)

Postupaev, V. V.; Batkin, V. I.; Beklemishev, A. D.; Burdakov, A. V.; Burmasov, V. S.; Chernoshtanov, I. S.; Gorbovsky, A. I.; Ivanov, I. A.; Kuklin, K. N.; Mekler, K. I.; Rovenskikh, A. F.; Sidorov, E. N.; Yurov, D. V.

2017-03-01

Physical and technical details of the GOL-NB project are presented. GOL-NB is a medium-scale multiple-mirror trap that is under development in the Budker Institute, Novosibirsk, Russia. This device will be created in several years as a deep conversion of the existing GOL-3 facility. It will consist of a central trap with two 0.75 MW neutral beams, two multiple-mirror solenoids, two expander tanks and a plasma gun that creates the start plasma. The central trap with the neutral beam injection-heated plasma is a compact gas-dynamic system. The multiple-mirror sections should decrease the power and particle losses along the magnetic field. The confinement improvement factor depends on plasma parameters and on the magnetic configuration in the multiple mirrors. The main physical task of GOL-NB is direct demonstration of the performance of multiple-mirror sections that will change equilibrium plasma parameters in the central trap. In this paper we discuss results of the scenario modeling and progress in the hardware.

Characterization of cross-section correction to charge exchange recombination spectroscopy rotation measurements using co- and counter-neutral-beam views.

PubMed

Solomon, W M; Burrell, K H; Feder, R; Nagy, A; Gohil, P; Groebner, R J

2008-10-01

Measurements of rotation using charge exchange recombination spectroscopy can be affected by the energy dependence of the charge exchange cross section. On DIII-D, the associated correction to the rotation can exceed 100 kms at high temperatures. In reactor-relevant low rotation conditions, the correction can be several times larger than the actual plasma rotation and therefore must be carefully validated. New chords have been added to the DIII-D CER diagnostic to view the counter-neutral-beam line. The addition of these views allows determination of the toroidal rotation without depending on detailed atomic physics calculations, while also allowing experimental characterization of the atomic physics. A database of rotation comparisons from the two views shows that the calculated cross-section correction can adequately describe the measurements, although there is a tendency for "overcorrection." In cases where accuracy better than about 15% is desired, relying on calculation of the cross-section correction may be insufficient.

Physics-based Control-oriented Modeling of the Current Profile Evolution in NSTX-Upgrade

NASA Astrophysics Data System (ADS)

Ilhan, Zeki; Barton, Justin; Shi, Wenyu; Schuster, Eugenio; Gates, David; Gerhardt, Stefan; Kolemen, Egemen; Menard, Jonathan

2013-10-01

The operational goals for the NSTX-Upgrade device include non-inductive sustainment of high- β plasmas, realization of the high performance equilibrium scenarios with neutral beam heating, and achievement of longer pulse durations. Active feedback control of the current profile is proposed to enable these goals. Motivated by the coupled, nonlinear, multivariable, distributed-parameter plasma dynamics, the first step towards feedback control design is the development of a physics-based, control-oriented model for the current profile evolution in response to non-inductive current drives and heating systems. For this purpose, the nonlinear magnetic-diffusion equation is coupled with empirical models for the electron density, electron temperature, and non-inductive current drives (neutral beams). The resulting first-principles-driven, control-oriented model is tailored for NSTX-U based on the PTRANSP predictions. Main objectives and possible challenges associated with the use of the developed model for control design are discussed. This work was supported by PPPL.

A Physical Model of the Proton Radiation Belts of Jupiter inside Europa's Orbit

NASA Astrophysics Data System (ADS)

Nénon, Q.; Sicard, A.; Kollmann, P.; Garrett, H. B.; Sauer, S. P. A.; Paranicas, C.

2018-05-01

A physical model of the Jovian trapped protons with kinetic energies higher than 1 MeV inward of the orbit of the icy moon Europa is presented. The model, named Salammbô, takes into account the radial diffusion process, the absorption effect of the Jovian moons, and the Coulomb collisions and charge exchanges with the cold plasma and neutral populations of the inner Jovian magnetosphere. Preliminary modeling of the wave-particle interaction with electromagnetic ion cyclotron waves near the moon Io is also performed. Salammbô is validated against in situ proton measurements of Pioneer 10, Pioneer 11, Voyager 1, Galileo Probe, and Galileo Orbiter. A prominent feature of the MeV proton intensity distribution in the modeled area is the 2 orders of magnitude flux depletion observed in MeV measurements near the orbit of Io. Our simulations reveal that this is not due to direct interactions with the moon or its neutral environment but results from scattering of the protons by electromagnetic ion cyclotron waves.

Radiative decay lifetime of neutrinos and the evolution of the universe after the recombination era

NASA Astrophysics Data System (ADS)

Rephaeli, Yoel; Szalay, Alexander S.

1981-10-01

If the radiative decay lifetime τ of massive neutrinos is less than 1025 s, but exceeding present constraints, the epoch of neutral hydrogen in the history of the universe could have been short or altogether absent. Erasure of small scale fluctuations in the cosmic microwave background radiation and other consequences of such lifetimes are discussed. From observations of neutral hydrogen in the nearby galaxy M 31 a lower limit τ >= 1024 s is obtained (for neutrino masses in the range 30 eV <= m <= 150 eV). Permanent address: Department of Atomic Physics, R. Eotvos University, 1088 Budapest, Hungary.

Flavour-changing neutral currents making and breaking the standard model.

PubMed

Archilli, F; Bettler, M-O; Owen, P; Petridis, K A

2017-06-07

The standard model of particle physics is our best description yet of fundamental particles and their interactions, but it is known to be incomplete. As yet undiscovered particles and interactions might exist. One of the most powerful ways to search for new particles is by studying processes known as flavour-changing neutral current decays, whereby a quark changes its flavour without altering its electric charge. One example of such a transition is the decay of a beauty quark into a strange quark. Here we review some intriguing anomalies in these decays, which have revealed potential cracks in the standard model-hinting at the existence of new phenomena.

Identification of extra neutral gauge bosons at the LHC using b and t quarks.

PubMed

Godfrey, Stephen; Martin, Travis A W

2008-10-10

New neutral gauge bosons (Z' 's) are predicted by many models of physics beyond the standard electroweak theory. It is possible that a Z' will be discovered by the Large Hadron Collider program. The next step would be to measure its properties to identify the underlying theory that gave rise to the Z'. Heavy quarks have the unique property that they can be identified in the final states. In this Letter we demonstrate that measuring Z' decays to b- and t-quark final states can act as an effective means of discriminating between models with extra gauge bosons.

Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

DOE PAGES

Dorf, Mikhail A.; Davidson, Ronald C.; Kaganovich, Igor D.; ...

2012-05-31

In this study, the design of ion drivers for warm dense matter and high energy density physics applications and heavy ion fusion involves transverse focusing and longitudinal compression of intense ion beams to a small spot size on the target. To facilitate the process, the compression occurs in a long drift section filled with a dense background plasma, which neutralizes the intense beam self-fields. Typically, the ion bunch charge is better neutralized than its current, and as a result a net self-pinching (magnetic) force is produced. The self-pinching effect is of particular practical importance, and is used in various ionmore » driver designs in order to control the transverse beam envelope. In the present work we demonstrate that this radial self-focusing force can be significantly enhanced if a weak (B~100 G) solenoidal magnetic field is applied inside the neutralized drift section, thus allowing for substantially improved transport. It is shown that in contrast to magnetic self-pinching, the enhanced collective self-focusing has a radial electric field component and occurs as a result of the overcompensation of the beam charge by plasmaelectrons, whereas the beam current becomes well-neutralized. As the beam leaves the neutralizing drift section, additional transverse focusing can be applied. For instance, in the neutralized drift compression experiments (NDCX) a strong (several Tesla) final focus solenoid is used for this purpose. In the present analysis we propose that the tight final focus in the NDCX experiments may possibly be achieved by using a much weaker (few hundred Gauss) magnetic lens, provided the ion beam carries an equal amount of co-moving neutralizing electrons from the preceding drift section into the lens. In this case the enhanced focusing is provided by the collective electrondynamics strongly affected by a weak applied magnetic field.« less

Measurement of a Neutrino-Induced Charged Current Single Neutral Pion Cross Section at MicroBooNE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hackenburg, Ariana

Micro Booster Neutrino Experiment (MicroBooNE) is a Liquid Argon Time Projection Chamber (LArTPC) operating in the Booster Neutrino Beamline at Fermi National Accelerator Laboratory. MicroBooNE's physics goals include studying short baslinemore » $$\

Effects of hydration on steric and electric charge-induced interstitial volume exclusion--a model.

PubMed

Øien, Alf H; Justad, Sigrid R; Tenstad, Olav; Wiig, Helge

2013-09-03

The presence of collagen and charged macromolecules like glycosaminoglycans (GAGs) in the interstitial space limits the space available for plasma proteins and other macromolecules. This phenomenon, known as interstitial exclusion, is of importance for interstitial fluid volume regulation. Physical/mathematical models are presented for calculating the exclusion of electrically charged and neutral macromolecules that equilibrate in the interstitium under various degrees of hydration. Here, a central hypothesis is that the swelling of highly electrically charged GAGs with increased hydration shields parts of the neutral collagen of the interstitial matrix from interacting with electrically charged macromolecules, such that exclusion of charged macromolecules exhibits change due to steric and charge effects. GAGs are also thought to allow relatively small neutral, but also charged macromolecules neutralized by a very high ionic strength, diffuse into the interior of GAGs, whereas larger macromolecules may not. Thus, in the model, relatively small electrically charged macromolecules, such as human serum albumin, and larger neutral macromolecules such as IgG, will have quite similar total volume exclusion properties in the interstitium. Our results are in agreement with ex vivo and in vivo experiments, and suggest that the charge of GAGs or macromolecular drugs may be targeted to increase the tissue uptake of macromolecular therapeutic agents. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

ECR Plasma Source for Heavy Ion Beam Charge Neutralization

NASA Astrophysics Data System (ADS)

Efthimion, P. C.; Gilson, E.; Grishman, L.; Kolchin, P.; Davidson, R. C.

2002-01-01

Highly ionized plasmas are being considered as a medium for charge neutralizing heavy ion beams in order to focus beyond the space-charge limit. Calculations suggest that plasma at a density of 1 - 100 times the ion beam density and at a length of approximately 0.1-2 m would be suitable for achieving a high level of charge neutralization. An ECR source has been built at the Princeton Plasma Physics Laboratory (PPPL) to support a joint Neutralized Transport Experiment (NTX) at the Lawrence Berkeley National Laboratory (LBNL) to study ion beam neutralization with plasma. The ECR source operates at 13.6 MHz and with solenoid magnetic fields of 1-10 gauss. The goal is to operate the source at pressures of approximately 10-6 torr at full ionization. The initial operation of the source has been at pressures of 10-4 - 10-1. Electron densities in the range of 108 - 1011 per cubic centimeter have been achieved. Low-pressure operation is important to reduce ion beam ionization. A cusp magnetic field has been installed to improve radial confinement and reduce the field strength on the beam axis. In addition, axial confinement is believed to be important to achieve lower-pressure operation. To further improve breakdown at low pressure, a weak electron source will be placed near the end of the ECR source.

RF Plasma Source for Heavy Ion Beam Charge Neutralization

NASA Astrophysics Data System (ADS)

Efthimion, P. C.; Gilson, E.; Grisham, L.; Davidson, R. C.

2003-10-01

Highly ionized plasmas are being employed as a medium for charge neutralizing heavy ion beams in order to focus to a small spot size. Calculations suggest that plasma at a density of 1 - 100 times the ion beam density and at a length 0.1-0.5 m would be suitable for achieving a high level of charge neutralization. An ECR source has been built at the Princeton Plasma Physics Laboratory (PPPL) in support of the joint Neutralized Transport Experiment (NTX) at the Lawrence Berkeley National Laboratory (LBNL) to study ion beam neutralization with plasma. The ECR source operates at 13.6 MHz and with solenoid magnetic fields of 0-10 gauss. The goal is to operate the source at pressures 10-5 Torr at full ionization. The initial operation of the source has been at pressures of 10-4 - 10-1 Torr. Electron densities in the range of 10^8 - 10^11 cm-3 have been achieved. Recently, pulsed operation of the source has enabled operation at pressures in the 10-6 Torr range with densities of 10^11 cm-3. Near 100% ionization has been achieved. The source has been integrated with NTX and is being used in the experiments. The plasma is approximately 10 cm in length in the direction of the beam propagation. Modifications to the source will be presented that increase its length in the direction of beam propagation.

Interactions between HIV-1 Neutralizing Antibodies and Model Lipid Membranes imaged with AFM

NASA Astrophysics Data System (ADS)

Zauscher, Stefan; Hardy, Gregory; Alam, Munir; Shapter, Joseph

2012-02-01

Lipid membrane interactions with rare, broadly neutralizing antibodies (NAbs), 2F5 and 4E10, play a critical role in HIV-1 neutralization. Our research is motivated by recent immunization studies that have shown that induction of antibodies that avidly bind the gp41-MPER antigen is not sufficient for neutralization. Rather, it is required that antigen designs induce polyreactive antibodies that recognize MPER antigens as well as the viral lipid membrane. However, the mechanistic details of how membrane properties influence NAb-lipid and NAb-antigen interactions remain unknown. Furthermore, it is well established that the native viral membrane is heterogeneous, representing a mosaic of lipid rafts and protein clustering. However, the size, physical properties, and dynamics of these regions are poorly characterized and their potential roles in HIV-1 neutralization are also unknown. To understand how membrane properties contribute to 2F5/4E10 membrane interactions, we have engineered biomimetic supported lipid bilayers (SLBs) and use atomic force microscopy to visualize membrane domains, antigen clustering, and antibody-membrane interactions at sub-nanometer z-resolution. Our results show that localized binding of HIV-1 antigens and NAbs occur preferentially with the most fluid membrane domain. This supports the theory that NAbs may interact with regions of low lateral lipid forces that allow antibody insertion into the bilayer.

Antibodyomics: bioinformatics technologies for understanding B-cell immunity to HIV-1.

PubMed

Kwong, Peter D; Chuang, Gwo-Yu; DeKosky, Brandon J; Gindin, Tatyana; Georgiev, Ivelin S; Lemmin, Thomas; Schramm, Chaim A; Sheng, Zizhang; Soto, Cinque; Yang, An-Suei; Mascola, John R; Shapiro, Lawrence

2017-01-01

Numerous antibodies have been identified from HIV-1-infected donors that neutralize diverse strains of HIV-1. These antibodies may provide the basis for a B cell-mediated HIV-1 vaccine. However, it has been unclear how to elicit similar antibodies by vaccination. To address this issue, we have undertaken an informatics-based approach to understand the genetic and immunologic processes controlling the development of HIV-1-neutralizing antibodies. As DNA sequencing comprises the fastest growing database of biological information, we focused on incorporating next-generation sequencing of B-cell transcripts to determine the origin, maturation pathway, and prevalence of broadly neutralizing antibody lineages (Antibodyomics1, 2, 4, and 6). We also incorporated large-scale robotic analyses of serum neutralization to identify and quantify neutralizing antibodies in donor cohorts (Antibodyomics3). Statistical analyses furnish another layer of insight (Antibodyomics5), with physical characteristics of antibodies and their targets through molecular dynamics simulations (Antibodyomics7) and free energy perturbation analyses (Antibodyomics8) providing information-rich output. Functional interrogation of individual antibodies (Antibodyomics9) and synthetic antibody libraries (Antibodyomics10) also yields multi-dimensional data by which to understand and improve antibodies. Antibodyomics, described here, thus comprise resolution-enhancing tools, which collectively embody an information-driven discovery engine aimed toward the development of effective B cell-based vaccines. © 2017 The Authors. Immunological Reviews published by John Wiley & Sons Ltd.

Self-confidence in and perceived utility of the physical examination: a comparison of medical students, residents, and faculty internists.

PubMed

Wu, Edward H; Fagan, Mark J; Reinert, Steven E; Diaz, Joseph A

2007-12-01

Little is known about the differences in attitudes of medical students, Internal Medicine residents, and faculty Internists toward the physical examination. We sought to investigate these groups' self-confidence in and perceived utility of physical examination skills. Cross-sectional survey of third- and fourth-year medical students, Internal Medicine residents, and faculty Internists at an academic teaching hospital. Using a 5-point Likert-type scale, respondents indicated their self-confidence in overall physical examination skill, as well as their ability to perform 14 individual skills, and how useful they felt the overall physical examination, and each skill, to be for yielding clinically important information. The response rate was 80% (302/376). The skills with overall mean self-confidence ratings less than "neutral" were interpreting a diastolic murmur (2.9), detecting a thyroid nodule (2.8), and the nondilated fundoscopic examination using an ophthalmoscope to assess retinal vasculature (2.5). No skills had a mean utility rating less than neutral. The skills with the greatest numerical differences between mean self-confidence and perceived utility were distinguishing between a mole and melanoma (1.5), detecting a thyroid nodule (1.4), and interpreting a diastolic murmur (1.3). Regarding overall self-confidence, third-year students' ratings (3.3) were similar to those of first-year residents (3.4; p = .95) but less than those of fourth-year students (3.8; p = .002), upper-level residents (3.7; p = .01), and faculty Internists (3.9; p < .001). Self-confidence in the physical exam does not necessarily increase at each stage of training. The differences found between self-confidence and perceived utility for a number of skills suggest important areas for educational interventions.

Testing the Standard Model by precision measurement of the weak charges of quarks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross Young; Roger Carlini; Anthony Thomas

In a global analysis of the latest parity-violating electron scattering measurements on nuclear targets, we demonstrate a significant improvement in the experimental knowledge of the weak neutral-current lepton-quark interactions at low-energy. The precision of this new result, combined with earlier atomic parity-violation measurements, limits the magnitude of possible contributions from physics beyond the Standard Model - setting a model-independent, lower-bound on the scale of new physics at ~1 TeV.

Extension and comparison of neoclassical models for poloidal rotation in tokamaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stacey, W. M.

2008-01-15

Several neoclassical models for the calculation of poloidal rotation in tokamaks were rederived within a common framework, extended to include additional physics and numerically compared. The importance of new physics phenomena not usually included in poloidal rotation calculations (e.g., poloidal electric field, VxB force resulting from enhanced radial particle flow arising from the ionization of recycling neutrals) was examined. Extensions of the Hirshman-Sigmar, Kim-Diamond-Groebner, and Stacey-Sigmar poloidal rotation models are presented.

Testing the standard model by precision measurement of the weak charges of quarks.

PubMed

Young, R D; Carlini, R D; Thomas, A W; Roche, J

2007-09-21

In a global analysis of the latest parity-violating electron scattering measurements on nuclear targets, we demonstrate a significant improvement in the experimental knowledge of the weak neutral-current lepton-quark interactions at low energy. The precision of this new result, combined with earlier atomic parity-violation measurements, places tight constraints on the size of possible contributions from physics beyond the standard model. Consequently, this result improves the lower-bound on the scale of relevant new physics to approximately 1 TeV.

Spectroscopy of antiprotonic helium atoms and its contribution to the fundamental physical constants

PubMed Central

Hayano, Ryugo S.

2010-01-01

Antiprotonic helium atom, a metastable neutral system consisting of an antiproton, an electron and a helium nucleus, was serendipitously discovered, and has been studied at CERN’s antiproton decelerator facility. Its transition frequencies have recently been measured to nine digits of precision by laser spectroscopy. By comparing these experimental results with three-body QED calculations, the antiproton-to-electron massratio was determined as 1836.152674(5). This result contributed to the CODATA recommended values of the fundamental physical constants. PMID:20075605

Unveiling the Diffuse, Neutral Interstellar Medium: Absorption Spectroscopy of Galactic Hydrogen

NASA Astrophysics Data System (ADS)

Murray, Claire Elizabeth

The formation of stars and evolution of galaxies depends on the cycle of interstellar matter between supernova-expelled plasma and molecule-rich gas. At the center of this cycle is multiphase neutral hydrogen (HI), whose physical conditions provide key ingredients to theoretical models. However, constraints for HI properties require measurements of gas emission and absorption which have been severely limited by previous observational capabilities. In this thesis, I present the largest survey of Galactic HI absorption ever undertaken with the Karl G. Jansky Very Large Array (VLA). The survey, 21 cm Spectral Line Observations of Neutral Gas with the VLA (21-SPONGE), is a statistical study of HI in all phases using direct absorption measurements. Leveraging novel calibration techniques, I demonstrate the capability of the VLA to detect a significant sample of 21 cm absorption lines from warm, diffuse HI. To maximize observational sensitivity, I stack the 21-SPONGE spectra and detect a pervasive signature of the warm neutral medium in absorption. The inferred excitation (or spin) temperature is consistent with existing estimates, yet higher than predictions from theoretical models of collisional HI excitation. This suggests that radiative feedback via resonant scattering of Lyalpha photons, known as the Wouthuysen-Field effect, is influential with important implications for cosmological 21 cm observations. Next, I compare 21-SPONGE with synthetic HI spectra from 3D numerical simulations using a new, objective decomposition and radiative transfer tool. I quantify the recovery of HI structures and their properties by Gaussian-fitted 21 cm spectral lines for the first time. I find that 21 cm absorption line shapes are sensitive to simulated physics, and demonstrate that my analysis method is a powerful tool for diagnosing neutral ISM conditions. Finally, I compare properties inferred from synthetic spectra with "true" simulation results to construct a bias correction function for estimating HI properties. I apply this correction to the mass distribution of HI as a function of temperature from 21-SPONGE, and find a significant fraction of thermally unstable gas. This confirms that non-steady radiative and dynamical processes, such as turbulence and supernovae, have a strong influence on the thermodynamic state of the ISM.

A physical workload index to evaluate a safe resident handling program for nursing home personnel.

PubMed

Kurowski, Alicia; Buchholz, Bryan; Punnett, Laura

2014-06-01

The aim of this study was to obtain a comprehensive analysis of the physical workload of clinical staff in long-term care facilities, before and after a safe resident handling program (SRHP). Ergonomic exposures of health care workers include manual handling of patients and many non-neutral postures. A comprehensive assessment requires the integration of loads from these varied exposures into a single metric. The Postures, Activities, Tools, and Handling observational protocol, customized for health care, was used for direct observations of ergonomic exposures in clinical jobs at 12 nursing homes before the SRHP and 3, 12, 24, and 36 months afterward. Average compressive forces on the spine were estimated for observed combinations of body postures and manual handling and then weighted by frequencies of observed time for the combination. These values were summed to obtain a biomechanical index for nursing assistants and nurses across observation periods. The physical workload index (PWI) was much higher for nursing assistants than for nurses and decreased more after 3 years (-24% versus -2.5%). Specifically during resident handling, the PWI for nursing assistants decreased by 41% of baseline value. Spinal loading was higher for nursing assistants than for nurses in long-term care centers. Both job groups experienced reductions in physical loading from the SRHP, especially the nursing assistants and especially while resident handling. The PWI facilitates a comprehensive investigation of physical loading from both manual handling and non-neutral postures. It can be used in any work setting to identify high-risk tasks and determine whether reductions in one exposure are offset by increases in another.

Multi-Higgs doublet models: physical parametrization, sum rules and unitarity bounds

NASA Astrophysics Data System (ADS)

Bento, Miguel P.; Haber, Howard E.; Romão, J. C.; Silva, João P.

2017-11-01

If the scalar sector of the Standard Model is non-minimal, one might expect multiple generations of the hypercharge-1/2 scalar doublet analogous to the generational structure of the fermions. In this work, we examine the structure of a Higgs sector consisting of N Higgs doublets (where N ≥ 2). It is particularly convenient to work in the so-called charged Higgs basis, in which the neutral Higgs vacuum expectation value resides entirely in the first Higgs doublet, and the charged components of remaining N - 1 Higgs doublets are mass-eigenstate fields. We elucidate the interactions of the gauge bosons with the physical Higgs scalars and the Goldstone bosons and show that they are determined by an N × 2 N matrix. This matrix depends on ( N - 1)(2 N - 1) real parameters that are associated with the mixing of the neutral Higgs fields in the charged Higgs basis. Among these parameters, N - 1 are unphysical (and can be removed by rephasing the physical charged Higgs fields), and the remaining 2( N - 1)2 parameters are physical. We also demonstrate a particularly simple form for the cubic interaction and some of the quartic interactions of the Goldstone bosons with the physical Higgs scalars. These results are applied in the derivation of Higgs coupling sum rules and tree-level unitarity bounds that restrict the size of the quartic scalar couplings. In particular, new applications to three Higgs doublet models with an order-4 CP symmetry and with a Z_3 symmetry, respectively, are presented.

40 CFR Appendix D to Part 300 - Appropriate Actions and Methods of Remedying Releases

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Neutralization. (D) Equalization. (E) Chemical oxidation. (iii) Physical methods, including the following: (A... treatment. (F) Wet air oxidation. (G) Solidification. (H) Encapsulation. (I) Soil washing or flushing. (J... containment. (iv) Leachate control, including the following: (A) Subsurface drains. (B) Drainage ditches. (C...

40 CFR Appendix D to Part 300 - Appropriate Actions and Methods of Remedying Releases

Code of Federal Regulations, 2014 CFR

2014-07-01

...) Neutralization. (D) Equalization. (E) Chemical oxidation. (iii) Physical methods, including the following: (A... treatment. (F) Wet air oxidation. (G) Solidification. (H) Encapsulation. (I) Soil washing or flushing. (J... containment. (iv) Leachate control, including the following: (A) Subsurface drains. (B) Drainage ditches. (C...

40 CFR Appendix D to Part 300 - Appropriate Actions and Methods of Remedying Releases

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Neutralization. (D) Equalization. (E) Chemical oxidation. (iii) Physical methods, including the following: (A... treatment. (F) Wet air oxidation. (G) Solidification. (H) Encapsulation. (I) Soil washing or flushing. (J... containment. (iv) Leachate control, including the following: (A) Subsurface drains. (B) Drainage ditches. (C...

Expected scientific results on ballistic spacecraft missions to comet Encke during the 1980 apparition

NASA Technical Reports Server (NTRS)

Mumma, M. J.

1976-01-01

Summarized are three proposed ballistic spacecraft missions to intercept P/Encke during the 1980 apparition. A baseline physical activity model for P/Encke is established and the performances of the neutral mass spectrometer and of the imaging experiment on each intercept mission are assessed.

Real-time Physiological Emotion Detection Mechanisms: Effects of Exercise and Affect Intensity.

PubMed

Leon, E; Clarke, G; Sepulveda, F; Callaghan, V

2005-01-01

The development of systems capable of recognizing and categorising emotions is of interest to researchers in various scientific areas including artificial intelligence. The traditional notion that emotions and rationality are two separate realms has gradually been challenged. The work of neurologists has shown the strong relationship between emotional episodes and the way humans think and act. Furthermore, emotions not only regulate human decisions but could also contribute to a more satisfactory response to the environment, i.e., faster and more precise actions. In this paper an analysis of physiological signals employed in real-time emotion detection is presented in the context of Intelligent Inhabited Environments (IIE). Two studies were performed to investigate whether physical exertion has a significant effect on bodily signals stemming from emotional episodes with subjects having various degrees of affect intensity: 1) a statistical analysis using the Wilcoxon Test, and 2) a cluster analysis using the Davies-Bouldin Index. Preliminary results demonstrated that the heart rate and skin resistance consistently showed similar changes regardless of the physical stimuli while blood volume pressure did not show a significant change. It was also found that neither physical stress nor affect intensity played a role in the separation of neutral and non-neutral emotional states.

Impact of dietary fiber and physical form on performance of lactating dairy cows.

PubMed

Woodford, J A; Jorgensen, N A; Barrington, G P

1986-04-01

Two trials were conducted to study the effects of forage intake and physical form on lactating cow performance. In trial 1, four cows in a 4 X 4 Latin square were fed long alfalfa hay at 28, 36, 45, and 53% of total dry matter plus concentrate. Total dry matter intake was not affected by forage percent. Total chewing time and milk fat percentage increased linearly with increasing forage consumption. Maximum 4% fat-corrected milk production occurred when diets contained 27% neutral detergent fiber and 18% acid detergent fiber. In trial 2, four cows in a 4 X 4 Latin square were fed diets of chopped alfalfa hay and concentrate in proportions to supply 27.4% total ration neutral detergent fiber. Mean particle length measured with an oscillating screen particle separator of the chopped hay was .26, .46, .64, and .90 cm. Total dry matter and forage dry matter intakes and total chewing were not influenced by forage mean particle length. Mean particle length did not affect actual milk or 4% fat-corrected milk production. Depression of milk fat percentage was prevented when forage mean particle length was greater than or equal .64 cm. Apparent digestibility of dietary constituents and rate of passage of hay and concentrate was not influenced by forage intake or physical form.

A blended continuous–discontinuous finite element method for solving the multi-fluid plasma model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sousa, E.M., E-mail: sousae@uw.edu; Shumlak, U., E-mail: shumlak@uw.edu

The multi-fluid plasma model represents electrons, multiple ion species, and multiple neutral species as separate fluids that interact through short-range collisions and long-range electromagnetic fields. The model spans a large range of temporal and spatial scales, which renders the model stiff and presents numerical challenges. To address the large range of timescales, a blended continuous and discontinuous Galerkin method is proposed, where the massive ion and neutral species are modeled using an explicit discontinuous Galerkin method while the electrons and electromagnetic fields are modeled using an implicit continuous Galerkin method. This approach is able to capture large-gradient ion and neutralmore » physics like shock formation, while resolving high-frequency electron dynamics in a computationally efficient manner. The details of the Blended Finite Element Method (BFEM) are presented. The numerical method is benchmarked for accuracy and tested using two-fluid one-dimensional soliton problem and electromagnetic shock problem. The results are compared to conventional finite volume and finite element methods, and demonstrate that the BFEM is particularly effective in resolving physics in stiff problems involving realistic physical parameters, including realistic electron mass and speed of light. The benefit is illustrated by computing a three-fluid plasma application that demonstrates species separation in multi-component plasmas.« less

Physical properties of botanical surfactants.

PubMed

Müller, Lillian Espíndola; Schiedeck, Gustavo

2018-01-01

Some vegetal species have saponins in their composition with great potential to be used as natural surfactants in organic crops. This work aims to evaluate some surfactants physical properties of Quillaja brasiliensis and Agave angustifolia, based on different methods of preparation and concentration. The vegetal samples were prepared by drying and grinding, frozen and after chopped or used fresh and chopped. The neutral bar soap was used as a positive control. The drying and grinding of samples were the preparation method that resulted in higher foam column height in both species but Q. brasiliensis was superior to A. angustifolia in all comparisons and foam index was 2756 and 1017 respectively. Critical micelle concentration of Q. brasiliensis was 0.39% with the superficial tension of 54.40mNm -1 while neutral bar soap was 0.15% with 34.96mNm -1 . Aspects such as genetic characteristics of the species, environmental conditions, and analytical methods make it difficult to compare the results with other studies, but Q. brasiliensis powder has potential to be explored as a natural surfactant in organic farming. Not only the surfactants physical properties of botanical saponins should be taken into account but also its effect on insects and diseases control when decided using them. Copyright © 2017 Elsevier B.V. All rights reserved.

Analgesic effect of Facebook: Priming with online social networking may boost felt relatedness that buffers against physical pain.

PubMed

Ho, Liang-Chu; Wu, Wen-Hsiung; Chiou, Wen-Bin

2016-10-01

Social networking sites (SNSs) are extremely popular for providing users with a convenient platform for acquiring social connections and thereby feeling relatedness. Plenty of literature has shown that mental representations of social support can reduce the perception of physical pain. The current study tested whether thinking about SNS would interfere with users' perceptions of experimentally induced pain. Ninety-six undergraduate Facebook users were recruited to participate in a priming-based experiment. They were randomly assigned to one of the three study conditions (SNS prime, neutral prime, or no prime) via rating the aesthetics of logos. The results showed that participants exposed to SNS primes reported less pain of immersion in hot water than did both control groups (neutral- and no-prime). Felt relatedness mediated the link between SNS primes and diminished pain perceptions. This research provides the first demonstration that thinking about SNS can lower experienced physical pain among Facebook users. Online social networking may serve as an analgesic buffer against pain experience than previously thought. The SNS-enabled analgesia has far reaching implications for pain relief applications and the enhancement of well-being in human-interaction techniques. © 2016 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Theoretical models of non-Maxwellian equilibria for one-dimensional collisionless plasmas

NASA Astrophysics Data System (ADS)

Allanson, O.; Neukirch, T.; Wilson, F.; Troscheit, S.

2016-12-01

It is ideal to use exact equilibrium solutions of the steady state Vlasov-Maxwell system to intialise collsionless simulations. However, exact equilibrium distribution functions (DFs) for a given macroscopic configuration are typically unknown, and it is common to resort to using `flow-shifted' Maxwellian DFs in their stead. These DFs may be consistent with a macrosopic system with the target number density and current density, but could well have inaccurate higher order moments. We present recent theoretical work on the `inverse problem in Vlasov-Maxwell equilibria', namely calculating an exact solution of the Vlasov equation for a specific given magnetic field. In particular, we focus on one-dimensional geometries in Cartesian (current sheets) coordinates.1. From 1D fields to Vlasov equilibria: Theory and application of Hermite Polynomials: (O. Allanson, T. Neukirch, S. Troscheit and F. Wilson, Journal of Plasma Physics, 82, 905820306 (2016) [28 pages, Open Access] )2. An exact collisionless equilibrium for the Force-Free Harris Sheet with low plasma beta: (O. Allanson, T. Neukirch, F. Wilson and S. Troscheit, Physics of Plasmas, 22, 102116 (2015) [11 pages, Open Access])3. Neutral and non-neutral collisionless plasma equilibria for twisted flux tubes: The Gold-Hoyle model in a background field (O. Allanson, F. Wilson and T. Neukirch, (2016)) (accepted, Physics of Plasmas)

Status of the charged Higgs boson in two Higgs doublet models

NASA Astrophysics Data System (ADS)

Arbey, A.; Mahmoudi, F.; Stål, O.; Stefaniak, T.

2018-03-01

The existence of charged Higgs boson(s) is inevitable in models with two (or more) Higgs doublets. Hence, their discovery would constitute unambiguous evidence for new physics beyond the Standard Model (SM). Taking into account all relevant results from direct charged and neutral Higgs boson searches at LEP and the LHC, as well as the most recent constraints from flavour physics, we present a detailed analysis of the current phenomenological status of the charged Higgs sector in a variety of well-motivated two Higgs doublet models (2HDMs). We find that charged Higgs bosons as light as 75 GeV can still be compatible with the combined data, although this implies severely suppressed charged Higgs couplings to all fermions. In more popular models, e.g. the 2HDM of Type II, we find that flavour physics observables impose a combined lower limit on the charged Higgs mass of M_{H^± } ≳ 600 GeV - independent of tan β - which increases to M_{H^± } ≳ 650 GeV for tan β < 1. We furthermore find that in certain scenarios, the signature of a charged Higgs boson decaying into a lighter neutral Higgs boson and a W boson provides a promising experimental avenue that would greatly complement the existing LHC search programme for charged Higgs boson(s).

Searching for New Physics via CP Violation in B → ππ

NASA Astrophysics Data System (ADS)

London, David; Sinha, Nita; Sinha, Rahul

We show how B → ππ decays can be used to search for new physics in the b → d flavour-changing neutral current. One needs one piece of theoretical input, which we take to be a prediction for P/T, the ratio of the penguin and tree amplitudes in B_d^0 to {π ^ + }{π ^ - }. If present, new physics can be detected over most of the parameter space. If α (ɸ2) can be obtained independently, measurements of B+ → π+π0 and B_d^0/overline {B_d^0} to {π ^0}{π ^0} are not even needed.

Physics with Trapped Antihydrogen

NASA Astrophysics Data System (ADS)

Charlton, Michael

2017-04-01

For more than a decade antihydrogen atoms have been formed by mixing antiprotons and positrons held in arrangements of charged particle (Penning) traps. More recently, magnetic minimum neutral atom traps have been superimposed upon the anti-atom production region, promoting the trapping of a small quantity of the antihydrogen yield. We will review these advances, and describe some of the first physics experiments performed on anrtihydrogen including the observation of the two-photon 1S-2S transition, invesigation of the charge neutrailty of the anti-atom and studies of the ground state hyperfine splitting. We will discuss the physics motivations for undertaking these experiments and describe some near-future initiatives.

Advances in antihydrogen physics.

PubMed

Charlton, Mike; Van der Werf, Dirk Peter

2015-01-01

The creation of cold antihydrogen atoms by the controlled combination of positrons and antiprotons has opened up a new window on fundamental physics. More recently, techniques have been developed that allow some antihydrogen atoms to be created at low enough kinetic energies that they can be held inside magnetic minimum neutral atom traps. With confinement times of many minutes possible, it has become feasible to perform experiments to probe the properties of the antiatom for the first time. We review the experimental progress in this area, outline some of the motivation for studying basic aspects of antimatter physics and provide an outlook of where we might expect this field to go in the coming years.

Physics with calorimeters

NASA Astrophysics Data System (ADS)

Pretzl, Klaus

2009-04-01

Calorimeters played an essential role in the discoveries of new physics, for example neutral currents (Gargamelle), quark and gluon jets (SPEAR, UA2, UA1 and PETRA), W and Z bosons (UA1, UA2), top quark (CDF, D0) and neutrino oscillations (SUPER-KAMIOKANDE, SNO). A large variety of different calorimeters have been developed covering an energy range between several and 1020 eV. This article tries to demonstrate on a few selected examples, such as the early jet searches in hadron-hadron collisions, direct dark matter searches, neutrino-less double beta decay and direct neutrino mass measurements, how the development of these devices has allowed to explore new frontiers in physics.

Laboratory Studies of Thermal Energy Charge Transfer of Silicon and Iron Ions in Astrophysical Plasmas

NASA Technical Reports Server (NTRS)

Kwong, Victor H. S.

1997-01-01

The laser ablation/ion storage facility at the UNLV Physics Department is dedicated to the study of atomic processes in low temperature plasmas. Our current program is directed to the study of charge transfer of multiply charged ions and neutrals that are of importance to astrophysics at energies less than 1 eV (about 10(exp 4) K). Specifically, we measure the charge transfer rate coefficient of ions such as N(2+), Si(3+), Si(3+), with helium and Fe(2+) with molecular and atomic hydrogen. All these ions are found in a variety of astrophysical plasmas. Their electron transfer reactions with neutral atoms can affect the ionization equilibrium of the plasma.

Cosmology on ultralarge scales with intensity mapping of the neutral hydrogen 21 cm emission: limits on primordial non-Gaussianity.

PubMed

Camera, Stefano; Santos, Mário G; Ferreira, Pedro G; Ferramacho, Luís

2013-10-25

The large-scale structure of the Universe supplies crucial information about the physical processes at play at early times. Unresolved maps of the intensity of 21 cm emission from neutral hydrogen HI at redshifts z=/~1-5 are the best hope of accessing the ultralarge-scale information, directly related to the early Universe. A purpose-built HI intensity experiment may be used to detect the large scale effects of primordial non-Gaussianity, placing stringent bounds on different models of inflation. We argue that it may be possible to place tight constraints on the non-Gaussianity parameter f(NL), with an error close to σ(f(NL))~1.

Active spectroscopic measurements of the bulk deuterium properties in the DIII-D tokamak (invited).

PubMed

Grierson, B A; Burrell, K H; Chrystal, C; Groebner, R J; Kaplan, D H; Heidbrink, W W; Muñoz Burgos, J M; Pablant, N A; Solomon, W M; Van Zeeland, M A

2012-10-01

The neutral-beam induced D(α) emission spectrum contains a wealth of information such as deuterium ion temperature, toroidal rotation, density, beam emission intensity, beam neutral density, and local magnetic field strength magnitude |B| from the Stark-split beam emission spectrum, and fast-ion D(α) emission (FIDA) proportional to the beam-injected fast ion density. A comprehensive spectral fitting routine which accounts for all photoemission processes is employed for the spectral analysis. Interpretation of the measurements to determine physically relevant plasma parameters is assisted by the use of an optimized viewing geometry and forward modeling of the emission spectra using a Monte-Carlo 3D simulation code.

Using polarized positrons to probe physics beyond the standard model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furletova, Yulia; Mantry, Sonny

A high intensity polarized positron beam, as part of the JLAB 12 GeV program and the proposed electron-ion collider (EIC), can provide a unique opportunity for testing the Standard Model (SM) and probing for new physics. The combination of high luminosity with polarized electrons and positrons incident on protons and deuterons can isolate important effects and distinguish between possible new physics scenarios in a manner that will complement current experimental efforts. Here, a comparison of cross sections between polarized electron and positron beams will allow for an extraction of the poorly known weak neutral current coupling combination 2C 3u -more » C 3d and would complement the proposed plan for a precision extraction of the combination 2C 2u - C d at the EIC. Precision measurements of these neutral weak couplings would constrain new physics scenarios including Leptoquarks, R-parity violating supersymmetry, and electron and quark compositeness. The dependence of the charged current cross section on the longitudinal polarization of the positron beam will provide an independent probe to test the chiral structure of the electroweak interactions. A polarized positron can probe charged lepton flavor violation (CLFV) through a search for e + → τ + transitions in a manner that is independent and complementary to the proposed e - → τ - search at the EIC. A positron beam incident on an electron in a stationary nuclear target will also allow for a dark-photon (A') search via the annihilation process e + + e - → A' + γ.« less

Using polarized positrons to probe physics beyond the standard model

DOE PAGES

Furletova, Yulia; Mantry, Sonny

2018-05-25

A high intensity polarized positron beam, as part of the JLAB 12 GeV program and the proposed electron-ion collider (EIC), can provide a unique opportunity for testing the Standard Model (SM) and probing for new physics. The combination of high luminosity with polarized electrons and positrons incident on protons and deuterons can isolate important effects and distinguish between possible new physics scenarios in a manner that will complement current experimental efforts. Here, a comparison of cross sections between polarized electron and positron beams will allow for an extraction of the poorly known weak neutral current coupling combination 2C 3u -more » C 3d and would complement the proposed plan for a precision extraction of the combination 2C 2u - C d at the EIC. Precision measurements of these neutral weak couplings would constrain new physics scenarios including Leptoquarks, R-parity violating supersymmetry, and electron and quark compositeness. The dependence of the charged current cross section on the longitudinal polarization of the positron beam will provide an independent probe to test the chiral structure of the electroweak interactions. A polarized positron can probe charged lepton flavor violation (CLFV) through a search for e + → τ + transitions in a manner that is independent and complementary to the proposed e - → τ - search at the EIC. A positron beam incident on an electron in a stationary nuclear target will also allow for a dark-photon (A') search via the annihilation process e + + e - → A' + γ.« less

Physics with antihydrogen

NASA Astrophysics Data System (ADS)

Bertsche, W. A.; Butler, E.; Charlton, M.; Madsen, N.

2014-12-01

Performing measurements of the properties of antihydrogen, the bound state of an antiproton and a positron, and comparing the results with those for ordinary hydrogen, has long been seen as a route to test some of the fundamental principles of physics. There has been much experimental progress in this direction in recent years, and antihydrogen is now routinely created and trapped and a range of exciting measurements probing the foundations of modern physics are planned or underway. In this contribution we review the techniques developed to facilitate the capture and manipulation of positrons and antiprotons, along with procedures to bring them together to create antihydrogen. Once formed, the antihydrogen has been detected by its destruction via annihilation or field ionization, and aspects of the methodologies involved are summarized. Magnetic minimum neutral atom traps have been employed to allow some of the antihydrogen created to be held for considerable periods. We describe such devices, and their implementation, along with the cusp magnetic trap used to produce the first evidence for a low-energy beam of antihydrogen. The experiments performed to date on antihydrogen are discussed, including the first observation of a resonant quantum transition and the analyses that have yielded a limit on the electrical neutrality of the anti-atom and placed crude bounds on its gravitational behaviour. Our review concludes with an outlook, including the new ELENA extension to the antiproton decelerator facility at CERN, together with summaries of how we envisage the major threads of antihydrogen physics will progress in the coming years.

Physics with antihydrogen

NASA Astrophysics Data System (ADS)

Bertsche, W. A.; Butler, E.; Charlton, M.; Madsen, N.

2015-12-01

Performing measurements of the properties of antihydrogen, the bound state of an antiproton and a positron, and comparing the results with those for ordinary hydrogen, has long been seen as a route to test some of the fundamental principles of physics. There has been much experimental progress in this direction in recent years, and antihydrogen is now routinely created and trapped and a range of exciting measurements probing the foundations of modern physics are planned or underway. In this contribution we review the techniques developed to facilitate the capture and manipulation of positrons and antiprotons, along with procedures to bring them together to create antihydrogen. Once formed, the antihydrogen has been detected by its destruction via annihilation or field ionization, and aspects of the methodologies involved are summarized. Magnetic minimum neutral atom traps have been employed to allow some of the antihydrogen created to be held for considerable periods. We describe such devices, and their implementation, along with the cusp magnetic trap used to produce the first evidence for a low-energy beam of antihydrogen. The experiments performed to date on antihydrogen are discussed, including the first observation of a resonant quantum transition and the analyses that have yielded a limit on the electrical neutrality of the anti-atom and placed crude bounds on its gravitational behaviour. Our review concludes with an outlook, including the new ELENA extension to the antiproton decelerator facility at CERN, together with summaries of how we envisage the major threads of antihydrogen physics will progress in the coming years.

Using polarized positrons to probe physics beyond the standard model

NASA Astrophysics Data System (ADS)

Furletova, Yulia; Mantry, Sonny

2018-05-01

A high intensity polarized positron beam, as part of the JLAB 12 GeV program and the proposed electron-ion collider (EIC), can provide a unique opportunity for testing the Standard Model (SM) and probing for new physics. The combination of high luminosity with polarized electrons and positrons incident on protons and deuterons can isolate important effects and distinguish between possible new physics scenarios in a manner that will complement current experimental efforts. A comparison of cross sections between polarized electron and positron beams will allow for an extraction of the poorly known weak neutral current coupling combination 2C3u - C3d and would complement the proposed plan for a precision extraction of the combination 2C2u - Cd at the EIC. Precision measurements of these neutral weak couplings would constrain new physics scenarios including Leptoquarks, R-parity violating supersymmetry, and electron and quark compositeness. The dependence of the charged current cross section on the longitudinal polarization of the positron beam will provide an independent probe to test the chiral structure of the electroweak interactions. A polarized positron can probe charged lepton flavor violation (CLFV) through a search for e+ → τ+ transitions in a manner that is independent and complementary to the proposed e- → τ- search at the EIC. A positron beam incident on an electron in a stationary nuclear target will also allow for a dark-photon (A') search via the annihilation process e+ + e- → A' + γ.

Subliminal perception of others' physical pain and pleasure.

PubMed

Chiesa, Patrizia Andrea; Liuzza, Marco Tullio; Acciarino, Adriano; Aglioti, Salvatore Maria

2015-08-01

Studies indicate that explicit and implicit processing of affectively charged stimuli may be reflected in specific behavioral markers and physiological signatures. This study investigated whether the pleasantness ratings of a neutral target were affected by subliminal perception of pleasant and painful facial expressions. Participants were presented images depicting face of non-famous models being slapped (painful condition), caressed (pleasant condition) or touched (neutral condition) by the right hand of another individual. In particular, we combined the continuous flash suppression technique with the affective misattribution procedure (AMP) to explore subliminal empathic processing. Measures of pupil reactivity along with empathy traits were also collected. Results showed that participants rated the neutral target as less or more likeable congruently with the painful or pleasant facial expression presented, respectively. Pupil dilation was associated both with the implicit attitudes (AMP score) and with empathic concern. Thus, the results provide behavioral and physiological evidence that state-related empathic reactivity can occur at an entirely subliminal level and that it is linked to autonomic responses and empathic traits.

Radiative Dileptonic Decays of B-Meson in the General Two Higgs Doublet Model

NASA Astrophysics Data System (ADS)

Erkol, G.; Turan, G.

2002-05-01

We investigate the exclusive B → γ ℓ + ℓ - decay in the general two Higgs Doublet Model (model III) including the neutral Higgs boson effects with an emphasis on possible CP-violating effects. For this decay, we analyze the dependencies of the forward-backward asymmetry of the lepton pair, AFB, CP-violating asymmetry, ACP, and the CP-violating asymmetry in forward-backward asymmetry, ACP(AFB), on the model parameters and also on the neutral Higgs boson effects. We have found that AFB˜ 10-1, 10-2, ACP˜ 10-2, 10-1 and ACP(AFB) ˜ 10-2, 10-1 depending on the relative magnitude of the Yukawa couplings bar ξ N,ttU and bar ξ N,bbD in the model III. We also observe that these physical quantities are sensitive to the model parameters and neutral Higgs boson effects are quite sizable for some values of the coupling bar ξ N,τ τ D.

Neutral sodium atoms extraction by micrometeoroid impacts on the surface of Mercury

NASA Astrophysics Data System (ADS)

Cremonese, G.; Orsini, S.; Capria, M. T.; Milillo, A.; Mura, A.; Mangano, V.; Carbognani, A.

2003-04-01

The Mercury's exosphere is more dependent on the micrometeoroid impacts than the lunar exosphere and we have applied an order-to-magnitude calculation on the physical conditions of the sodium atoms during these events. This calculation shows the different ionization degree of sodium atoms depending on the meteoroid impact velocity and the related emission enhancements we may have observing the exosphere. We have applied the same calculation to the visible and UV doublets showing the large difference, a factor 5, between the two emission intensities only taking into account the same micrometeoroids contribution. Furthermore we provide a rough estimate for the impact magnitude in sodium light if we observe the night side of the Mercury's surface from the orbit of the ESA mission BepiColombo. Assuming a specific energy distribution of the emitted neutrals, we simulate the characteristics of the low-energy neutral atom fluxes as observable by the SERENA/ELENA instrument proposed on board the ESA BepiColombo Planetary Orbiter.

Preattentive processing of heart cues and the perception of heart symptoms in congenital heart disease.

PubMed

Karsdorp, Petra A; Kindt, Merel; Everaerd, Walter; Mulder, Barbara J M

2007-08-01

The present study was aimed at clarifying whether preattentive processing of heart cues results in biased perception of heart sensations in patients with congenital heart disease (ConHD) who are also highly trait anxious. Twenty-six patients with ConHD and 22 healthy participants categorized heart-related (heart rate) or neutral sensations (constant vibration) as either heart or neutral. Both sensations were evoked using a bass speaker that was attached on the chest of the participant. Before each physical sensation, a subliminal heart-related or neutral prime was presented. Biased perception of heart-sensations would become evident by a delayed categorization of the heart-related sensations. In line with the prediction, a combination of high trait anxiety and ConHD resulted in slower responses after a heart-related sensation that was preceded by a subliminal heart cue. Preattentive processing of harmless heart cues may easily elicit overperception of heart symptoms in highly trait anxious patients with ConHD.

A Model of the Influence of Neutral Air Dynamics on the Seasonal Variation in the Low Ionosphere

NASA Technical Reports Server (NTRS)

Nestorov, G.; Velinov, P. J.; Pancheva, T.

1984-01-01

Recently it has become clear that the phenomena in the ionospheric D-region are determined to a great extent by dynamical processes in the strato-mesosphere D-region. In this respect much attention is paid to the study of the winter anomaly (WA) phenomenon on medium and short radiowaves, in which the meteorological character of the lower ionosphere is most prominent. Significant experimental data about the variations of the electron concentration, N, ion composition, temperature and dynamic regime during WA permit a better understanding of the character of the physical processes in the middle atmosphere. The influence of the neutral wind on the seasonal variation of the electron concentration N for the altitude interval 90 or = z or = 120 km, where the ratio upsilon sub in/omega sub i, of the ion-neutral collision frequency, upsilon sub in and the ion gyrofrequency, omega sub i decreases from 40 to 1 was evaluated. CIRA-72 is used as a model of the zonal wind.

Variability in the topside ionosphere of Mars as seen by the MAVEN NGIMS instrument

NASA Astrophysics Data System (ADS)

Mayyasi, M.; Benna, M.; Mahaffy, P. R.; Elrod, M. K.

2017-12-01

Topside features in the ionosphere of Mars have been observed with every class of instrument to make ionospheric measurements of the planet. Many of these features include plasma enhancements that persist above the main ionospheric layer. A variety of physical mechanisms have been proposed to produce these enhancements, yet there remain inconsistencies between observational trends and theoretical drivers. The NASA Mars Atmosphere and Volatile Evolution mission Neutral Gas and Ion Mass Spectrometer (NGIMS) instrument is making in situ measurements to provide the chemical composition of the Martian ionized and neutral atmosphere. NGIMS observations typically span the altitude region at Mars in which both the ionospheric peak and topside plasma features are observed. In this presentation, NGIMS electron density data is analyzed for detections of topside enhancements that are closest to and above the main ionospheric peak. The ion composition of the detected topside bulges are subsequently analyzed against the ambient neutral species measurements and topographic parameters for insights into the mechanisms likely to be producing these enigmatic features.

Conceptual design of the DEMO neutral beam injectors: main developments and R&D achievements

NASA Astrophysics Data System (ADS)

Sonato, P.; Agostinetti, P.; Bolzonella, T.; Cismondi, F.; Fantz, U.; Fassina, A.; Franke, T.; Furno, I.; Hopf, C.; Jenkins, I.; Sartori, E.; Tran, M. Q.; Varje, J.; Vincenzi, P.; Zanotto, L.

2017-05-01

The objectives of the nuclear fusion power plant DEMO, to be built after the ITER experimental reactor, are usually understood to lie somewhere between those of ITER and a ‘first of a kind’ commercial plant. Hence, in DEMO the issues related to efficiency and RAMI (reliability, availability, maintainability and inspectability) are among the most important drivers for the design, as the cost of the electricity produced by this power plant will strongly depend on these aspects. In the framework of the EUROfusion Work Package Heating and Current Drive within the Power Plant Physics and Development activities, a conceptual design of the neutral beam injector (NBI) for the DEMO fusion reactor has been developed by Consorzio RFX in collaboration with other European research institutes. In order to improve efficiency and RAMI aspects, several innovative solutions have been introduced in comparison to the ITER NBI, mainly regarding the beam source, neutralizer and vacuum pumping systems.

Short intense ion pulses for materials and warm dense matter research

NASA Astrophysics Data System (ADS)

Seidl, Peter A.; Persaud, Arun; Waldron, William L.; Barnard, John J.; Davidson, Ronald C.; Friedman, Alex; Gilson, Erik P.; Greenway, Wayne G.; Grote, David P.; Kaganovich, Igor D.; Lidia, Steven M.; Stettler, Matthew; Takakuwa, Jeffrey H.; Schenkel, Thomas

2015-11-01

We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r<1 mm within 2 ns FWHM and approximately 1010 ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li+ ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Here we describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminum perovskite using the fully integrated accelerator and neutralized drift compression components.

Flotation mechanisms of molybdenite fines by neutral oils

NASA Astrophysics Data System (ADS)

Lin, Qing-quan; Gu, Guo-hua; Wang, Hui; Liu, You-cai; Fu, Jian-gang; Wang, Chong-qing

2018-01-01

The flotation mechanisms of molybdenite fines by neutral oils were investigated through microflotation test, turbidity measurements, infrared spectroscopy, and interfacial interaction calculations. The results of the flotation test show that at pH 2-11, the floatability of molybdenite fines in the presence of transformer oil is markedly better than that in the presence of kerosene and diesel oil. The addition of transformer oil, which enhances the floatability of molybdenite fines, promotes the aggregation of molybdenite particles. Fourier transform infrared measurements illustrate that physical interaction dominates the adsorption mechanism of neutral oil on molybdenite. Interfacial interaction calculations indicate that hydrophobic attraction is the crucial force that acts among the oil collector, water, and molybdenite. Strong hydrophobic attraction between the oily collector and water provides the strong dispersion capability of the collector in water. Furthermore, the dispersion capability of the collector, not the interaction strength between the oily collectors and molybdenite, has a highly significant role in the flotation system of molybdenite fines. Our findings provide insights into the mechanism of molybdenite flotation.

Molecular Anions in Protostars, Prestellar Cores and Dark Clouds

NASA Technical Reports Server (NTRS)

Cordiner, Martin; Charnley, Steven; Buckle, Jane; Wash, Catherine; Millar, Tom

2011-01-01

From our recent survey work using the Green Bank Telescope, microwave emission lines from the hydrocarbon anion C6H(-) and its parent neutral C6H have been detected in six new sources. Using HC3N = 10(exp -9) emission maps, we targeted the most carbon-chain-rich sources for our anion survey, which included the low-mass Class 0 protostar L1251A-IRS3, the prestellar cores L1389-SMM1 and L1512, and the interstellar clouds Ll172A, TMC-1C and L1495B. Derived [C6H(-)]/[C6H] anion-to-neutral ratios are approximately 1-10. The greatest C6H(-) column densities are found in the quiescent clouds TMC-1C and L1495B, but the anion-to-neutral ratios are greatest in the prestellar cores and protostars. These results are interpreted in terms of the physical and chemical properties of the sources, and the implications for molecular cloud chemistry are discussed.

Transport of neutral solute across articular cartilage: the role of zonal diffusivities.

PubMed

Arbabi, V; Pouran, B; Weinans, H; Zadpoor, A A

2015-07-01

Transport of solutes through diffusion is an important metabolic mechanism for the avascular cartilage tissue. Three types of interconnected physical phenomena, namely mechanical, electrical, and chemical, are all involved in the physics of transport in cartilage. In this study, we use a carefully designed experimental-computational setup to separate the effects of mechanical and chemical factors from those of electrical charges. Axial diffusion of a neutral solute Iodixanol into cartilage was monitored using calibrated microcomputed tomography micro-CT images for up to 48 hr. A biphasic-solute computational model was fitted to the experimental data to determine the diffusion coefficients of cartilage. Cartilage was modeled either using one single diffusion coefficient (single-zone model) or using three diffusion coefficients corresponding to superficial, middle, and deep cartilage zones (multizone model). It was observed that the single-zone model cannot capture the entire concentration-time curve and under-predicts the near-equilibrium concentration values, whereas the multizone model could very well match the experimental data. The diffusion coefficient of the superficial zone was found to be at least one order of magnitude larger than that of the middle zone. Since neutral solutes were used, glycosaminoglycan (GAG) content cannot be the primary reason behind such large differences between the diffusion coefficients of the different cartilage zones. It is therefore concluded that other features of the different cartilage zones such as water content and the organization (orientation) of collagen fibers may be enough to cause large differences in diffusion coefficients through the cartilage thickness.

Laser Induced Fluorescence Spectroscopy of Neutral and Ionized Polycyclic Aromatic Hydrocarbons in the Cosmic Simulation Chamber

NASA Technical Reports Server (NTRS)

Bejaoui, Salma; Salama, Farid; Contreras, Cesar; Sciamma O'Brien, Ella; Foing, Bernard; Pascale, Ehrenfreund

2015-01-01

Polycyclic aromatic hydrocarbon (PAH) molecules are considered the best carriers to account for the ubiquitous infrared emission bands. PAHs have also been proposed as candidates to explain the diffuse interstellar bands (DIBs), a series of absorption features seen on the interstellar extinction curve and are plausible carriers for the extended red emission (ERE), a photoluminescent process associated with a wide variety of interstellar environments. Extensive efforts have been devoted over the past two decades to characterize the physical and chemical properties of PAH molecules and ions in space. Absorption spectra of PAH molecules and ions trapped in solid matrices have been compared to the DIBs. Absorption spectra of several cold, isolated gas-phase PAHs have also been measured under experimental conditions that mimic the interstellar conditions. The purpose of this study is to provide a new dimension to the existing spectroscopic database of neutral and single ionized PAHs that is largely based on absorption spectra by adding emission spectroscopy data. The measurements are based on the laser induced fluorescence (LIF) technique and are performed with the Pulsed Discharge Nozzle (PDN) of the COSmIC laboratory facility at NASA Ames laboratory. The PDN generates a plasma in a free supersonic jet expansion to simulate the physical and the chemical conditions in interstellar environments. We focus, here, on the fluorescence spectra of large neutral PAHs and their cations where there is a lack of fluorescence spectroscopy data. The astronomical implications of the data (e.g., ERE) are examined.

Time-resolved ion energy and charge state distributions in pulsed cathodic arc plasmas of Nb‑Al cathodes in high vacuum

NASA Astrophysics Data System (ADS)

Zöhrer, Siegfried; Anders, André; Franz, Robert

2018-05-01

Cathodic arcs have been utilized in various applications including the deposition of thin films and coatings, ion implantation, and high current switching. Despite substantial progress in recent decades, the physical mechanisms responsible for the observed plasma properties are still a matter of dispute, particularly for multi-element cathodes, which can play an essential role in applications. The analysis of plasma properties is complicated by the generally occurring neutral background of metal atoms, which perturbs initial ion properties. By using a time-resolved method in combination with pulsed arcs and a comprehensive Nb‑Al cathode model system, we investigate the influence of cathode composition on the plasma, while making the influence of neutrals visible for the observed time frame. The results visualize ion detections of 600 μs plasma pulses, extracted 0.27 m from the cathode, resolved in mass-per-charge, energy-per-charge and time. Ion properties are found to be strongly dependent on the cathode material in a way that cannot be deduced by simple linear extrapolation. Subsequently, current hypotheses in cathodic arc physics applying to multi-element cathodes, like the so-called ‘velocity rule’ or the ‘cohesive energy rule’, are tested for early and late stages of the pulse. Apart from their fundamental character, the findings could be useful in optimizing or designing plasma properties for applications, by actively utilizing effects on ion distributions caused by composite cathode materials and charge exchange with neutrals.

Midlatitude Sporadic E Layers: Physical mechanisms and observational characteristics

NASA Astrophysics Data System (ADS)

Haldoupis, Christos

The sporadic E and its abbreviation Es refer to rather thin layers of metallic ions which form in the dynamo region of the Earth’s ionosphere, mostly between 100 and 130 km, where ion motion is controlled by collisions with the neutrals, making them move with the local winds, while electrons are strongly magnetized. The physics of sporadic E relies on the Windshear theory, in which vertical shears in the horizontal wind can form layers of long-lived metallic ions through the combined action of ion-neutral collisional coupling and geomagnetic Lorentz forcing. Once formed, the layers tend to gradually descend with time downwards below 100 km where they eventually disappear because of 3-body recombination that becomes increasingly effective in depleting them of their plasma. This is a comprehensive presentation on sporadic E, a topic which has been researched extensively over many decades. First, it reviews the basics of windshear theory and its plasma convergence mechanisms and then updates our physical understanding through a synthesis of key observational characteristics and findings. The emphasis is placed on the wind shear control of the diurnal and sub-diurnal variability and altitude descent of sporadic E layers and the key role behind this of atmospheric tides, which also drive the formation of upper E region descending intermediate layers (IDL). The evidence suggests that IDLs constitute an integral part within a broader sporadic E layer system. The presentation summarizes observations that establish a role also for the planetary waves which, through the modulation of tides, affect sporadic E layer occurrence and longer-term variability. In addition, findings are presented that provide a better physical insight in relation with the seasonal dependence and the global occurrence of sporadic E layers. The observational facts imply that sporadic E is controlled macroscopically mostly by tidal and planetary wind atmospheric dynamics, the Earth’s magnetic field and the mean meteoric deposition. Finally, traces of sporadic E in altitude and time may help evaluate and validate neutral wind model predictions in the lower thermosphere.

Brookhaven highlights, October 1978-September 1979. [October 1978 to September 1979

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1979-01-01

These highlights present an overview of the major research and development achievements at Brookhaven National Laboratory from October 1978 to September 1979. Specific areas covered include: accelerator and high energy physics programs; high energy physics research; the AGS and improvements to the AGS; neutral beam development; heavy ion fusion; superconducting power cables; ISABELLE storage rings; the BNL Tandem accelerator; heavy ion experiments at the Tandem; the High Flux Beam Reactor; medium energy physics; nuclear theory; atomic and applied physics; solid state physics; neutron scattering studies; x-ray scattering studies; solid state theory; defects and disorder in solids; surface physics; the Nationalmore » Synchrotron Light Source ; Chemistry Department; Biology Department; Medical Department; energy sciences; environmental sciences; energy technology programs; National Center for Analysis of Energy Systems; advanced reactor systems; nuclear safety; National Nuclear Data Center; nuclear materials safeguards; Applied Mathematics Department; and support activities. (GHT)« less

ELENA MCP detector: absolute detection efficiency for low-energy neutral atoms

NASA Astrophysics Data System (ADS)

Rispoli, R.; De Angelis, E.; Colasanti, L.; Vertolli, N.; Orsini, S.; Scheer, J. A.; Mura, A.; Milillo, A.; Wurz, P.; Selci, S.; Di Lellis, A. M.; Leoni, R.; D'Alessandro, M.; Mattioli, F.; Cibella, S.

2012-09-01

Microchannel Plates (MCP) detectors are frequently used in space instrumentation for detecting a wide range of radiation and particles. In particular, the capability to detect non-thermal low energy neutral species is crucial for the sensor ELENA (Emitted Low-Energy Neutral Atoms), part of the package SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) on board the BepiColombo mission of ESA to Mercury to be launched in 2015. ELENA is a Time of Flight (TOF) sensor, based on a novel concept using an ultra-sonic oscillating shutter (Start section), which is operated at frequencies up to 50 kHz; a MCP detector is used as a Stop detector. The scientific objective of ELENA is to detect energetic neutral atoms in the range 10 eV - 5 keV, within 76° FOV, perpendicular to the S/C orbital plane. ELENA will monitor the emission of neutral atoms from the whole surface of Mercury thanks to the spacecraft motion. The major scientific objectives are the interaction between the plasma environment and the planet’s surface, the global particle loss-rate and the remote sensing of the surface properties. In particular, surface release processes are investigated by identifying particles released from the surface, via solar wind-induced ion sputtering (< 1eV - < 100 eV) as well as Hydrogen back-scattered at hundreds eV. MCP absolute detection efficiency for very low energy neutral atoms (E < 30 eV) is a crucial point for this investigation. At the MEFISTO facility of the Physical Institute of the University of Bern (CH), measurements on three different types of MCP (with and without coating) have been performed providing the detection efficiencies in the energy range 10eV - 1keV. Outcomes from such measurements are discussed here.

ELENA MCP detector: absolute efficiency measurement for low energy neutral atoms

NASA Astrophysics Data System (ADS)

Rispoli, R.; De Angelis, E.; Colasanti, L.; Vertolli, N.; Orsini, S.; Scheer, J.; Mura, A.; Milillo, A.; Wurz, P.; Selci, S.; Di Lellis, A. M.; Leoni, R.; D'Alessandro, M.; Mattioli, F.; Cibella, S.

2012-04-01

MicroChannel plates (MCP) detectors are frequently used in space instrumentation for detecting a wide range of radiation and particles. In particular, the capability to detect non-thermal low energy neutral species is crucial for the sensor ELENA (Emitted Low-Energy Neutral Atoms), part of the package SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) on board the BepiColombo mission to Mercury to be launched in 2014. ELENA is a TOF sensor, based on a novel concept ultra-sonic oscillating shutter (Start section)which is operated at frequencies up to 50 kHz; a MCP detector is used as a Stop section. It is aimed to detect neutral atoms in the range 10 eV - 5 keV, within 70° FOV, perpendicular to the S/C orbital plane. ELENA will monitor the emission of neutral atoms from the whole surface of Mercury thanks to the spacecraft motion. The major scientific objectives are the interaction between the environment and the planet, the global particle loss-rate and the remote sensing of the surface properties. In particular, surface release processes are investigated by identifying particles release from the surface, via solar wind-induced ion sputtering (<1eV and >100 eV) as well as Hydrogen back-scattered at hundreds eV. MCP absolute detection efficiency for very low energy neutral atoms (E< 30eV) is a crucial point not yet investigated. At the MEFISTO facility of the Physical Institute of University of Bern (CH), measurements on three different type of MCPs coating have been performed providing the behaviors of MCP detection efficiency in the range 10eV-1keV. Outcomes from such measurements are here discussed.

PAHs and the Diffuse Interstellar Bands. What have we Learned from the New Generation of Laboratory and Observational Studies?

NASA Technical Reports Server (NTRS)

Salama, Farid

2005-01-01

Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. PAHs are the best-known candidates to account for the IR emission bands (UIR bands) and PAH spectral features are now being used as new probes of the ISM. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory astrophysics is to reproduce (in a realistic way) the physical conditions that exist in the emission and/or absorption interstellar zones, An extensive laboratory program has been developed at NASA Ames to characterize the physical and chemical properties of PAHs in astrophysical environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. In particular, laboratory experiments provide measurements of the spectral characteristics of interstellar PAH analogs from the ultraviolet and visible range to the infrared range for comparison with astronomical data. This paper will focus on the recent progress made in the laboratory to measure the direct absorption spectra of neutral and ionized PAHs in the gas phase in the near-W and visible range in astrophysically relevant environments. These measurements provide data on PAHs and nanometer-sized particles that can now be directly compared to astronomical observations. The harsh physical conditions of the IS medium - characterized by a low temperature, an absence of collisions and strong V W radiation fields - are simulated in the laboratory by associating a molecular beam with an ionizing discharge to generate a cold plasma expansion. PAH ions are formed from the neutral precursors in an isolated environment at low temperature (of the order of 100 K). The spectra of neutral and ionized PAHs are measured using the high sensitivity methods of cavity ring down spectroscopy (CRDS). These experiments provide unique information on the spectra of free, cold large carbon molecules and ions in the gas phase. Intrinsic band profiles and band positions of cold gas-phase PAHs can now be measured with high- sensitivity spectroscopy and directly compared to the astronomical data. The electronic bands measured for ionized PAH are found to be intrinsically broad (about 20/cm) while the bands associated with the neutral precursors are narrower (of the order of 2 - 10/cm).

NON-NEUTRALIZED ELECTRIC CURRENT PATTERNS IN SOLAR ACTIVE REGIONS: ORIGIN OF THE SHEAR-GENERATING LORENTZ FORCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Georgoulis, Manolis K.; Titov, Viacheslav S.; Mikic, Zoran

Using solar vector magnetograms of the highest available spatial resolution and signal-to-noise ratio, we perform a detailed study of electric current patterns in two solar active regions (ARs): a flaring/eruptive and a flare-quiet one. We aim to determine whether ARs inject non-neutralized (net) electric currents in the solar atmosphere, responding to a debate initiated nearly two decades ago that remains inconclusive. We find that well-formed, intense magnetic polarity inversion lines (PILs) within ARs are the only photospheric magnetic structures that support significant net current. More intense PILs seem to imply stronger non-neutralized current patterns per polarity. This finding revises previousmore » works that claim frequent injections of intense non-neutralized currents by most ARs appearing in the solar disk but also works that altogether rule out injection of non-neutralized currents. In agreement with previous studies, we also find that magnetically isolated ARs remain globally current-balanced. In addition, we confirm and quantify the preference of a given magnetic polarity to follow a given sense of electric currents, indicating a dominant sense of twist in ARs. This coherence effect is more pronounced in more compact ARs with stronger PILs and must be of sub-photospheric origin. Our results yield a natural explanation of the Lorentz force, invariably generating velocity and magnetic shear along strong PILs, thus setting a physical context for the observed pre-eruption evolution in solar ARs.« less

Optimization of Neutral Atom Imagers

NASA Technical Reports Server (NTRS)

Shappirio, M.; Coplan, M.; Balsamo, E.; Chornay, D.; Collier, M.; Hughes, P.; Keller, J.; Ogilvie, K.; Williams, E.

2008-01-01

The interactions between plasma structures and neutral atom populations in interplanetary space can be effectively studied with energetic neutral atom imagers. For neutral atoms with energies less than 1 keV, the most efficient detection method that preserves direction and energy information is conversion to negative ions on surfaces. We have examined a variety of surface materials and conversion geometries in order to identify the factors that determine conversion efficiency. For chemically and physically stable surfaces smoothness is of primary importance while properties such as work function have no obvious correlation to conversion efficiency. For the noble metals, tungsten, silicon, and graphite with comparable smoothness, conversion efficiency varies by a factor of two to three. We have also examined the way in which surface conversion efficiency varies with the angle of incidence of the neutral atom and have found that the highest efficiencies are obtained at angles of incidence greater then 80deg. The conversion efficiency of silicon, tungsten and graphite were examined most closely and the energy dependent variation of conversion efficiency measured over a range of incident angles. We have also developed methods for micromachining silicon in order to reduce the volume to surface area over that of a single flat surface and have been able to reduce volume to surface area ratios by up to a factor of 60. With smooth micro-machined surfaces of the optimum geometry, conversion efficiencies can be increased by an order of magnitude over instruments like LENA on the IMAGE spacecraft without increase the instruments mass or volume.

The effects on the ionosphere of inertia in the high latitude neutral thermosphere

NASA Technical Reports Server (NTRS)

Burns, Alan; Killeen, Timothy

1993-01-01

High-latitude ionospheric currents, plasma temperatures, densities, and composition are all affected by the time-dependent response of the neutral thermosphere to ion drag and Joule heating through a variety of complex feedback processes. These processes can best be studied numerically using the appropriate nonlinear numerical modeling techniques in conjunction with experimental case studies. In particular, the basic physics of these processes can be understood using a model, and these concepts can then be applied to more complex realistic situations by developing the appropriate simulations of real events. Finally, these model results can be compared with satellite-derived data from the thermosphere. We used numerical simulations from the National Center of Atmospheric Research Thermosphere/Ionosphere General Circulation Model (NCAR TIGCM) and data from the Dynamic Explorer 2 (DE 2) satellite to study the time-dependent effects of the inertia of the neutral thermosphere on ionospheric currents, plasma temperatures, densities, and composition. One particular case of these inertial effects is the so-called 'fly-wheel effect'. This effect occurs when the neutral gas, that has been spun-up by the large ionospheric winds associated with a geomagnetic storm, moves faster than the ions in the period after the end of the main phase of the storm. In these circumstances, the neutral gas can drag the ions along with them. It is this last effect, which is described in the next section, that we have studied under this grant.

A comparative study on the raft chemical properties of various alginate antacid raft-forming products.

PubMed

Dettmar, Peter W; Gil-Gonzalez, Diana; Fisher, Jeanine; Flint, Lucy; Rainforth, Daniel; Moreno-Herrera, Antonio; Potts, Mark

2018-01-01

Research to measure the chemical characterization of alginate rafts for good raft performance and ascertain how formulation can affect chemical parameters. A selection of alginate formulations was investigated all claiming to be proficient raft formers with significance between products established and ranked. Procedures were selected which demonstrated the chemical characterization allowing rafts to effectively impede the reflux into the esophagus or in severe cases to be refluxed preferentially into the esophagus and exert a demulcent effect, with focus of current research on methods which complement previous studies centered on physical properties. The alginate content was analyzed by a newly developed HPLC method. Methods were used to determine the neutralization profile and the acid neutralization within the raft determined along with how raft structure affects neutralization. Alginate content of Gaviscon Double Action (GDA) within the raft was significantly superior (p < .0001) to all competitor products. The two products with the highest raft acid neutralization capacity were GDA and Rennie Duo, the latter product not being a raft former. Raft structure was key and GDA had the right level of porosity to allow for longer duration of neutralization. Alginate formulations require three chemical reactions to take place simultaneously: transformation to alginic acid, sodium carbonate reacting to form carbon dioxide, calcium releasing free calcium ions to bind with alginic acid providing strength to raft formation. GDA was significantly superior (p <.0001) to all other comparators.

(?) The Air Force Geophysics Laboratory: Aeronomy, aerospace instrumentation, space physics, meteorology, terrestrial sciences and optical physics

NASA Astrophysics Data System (ADS)

McGinty, A. B.

1982-04-01

Contents: The Air Force Geophysics Laboratory; Aeronomy Division--Upper Atmosphere Composition, Middle Atmosphere Effects, Atmospheric UV Radiation, Satellite Accelerometer Density Measurement, Theoretical Density Studies, Chemical Transport Models, Turbulence and Forcing Functions, Atmospheric Ion Chemistry, Energy Budget Campaign, Kwajalein Reference Atmospheres, 1979, Satellite Studies of the Neutral Atmosphere, Satellite Studies of the Ionosphere, Aerospace Instrumentation Division--Sounding Rocket Program, Satellite Support, Rocket and Satellite Instrumentation; Space Physics Division--Solar Research, Solar Radio Research, Environmental Effects on Space Systems, Solar Proton Event Studies, Defense Meteorological Satellite Program, Ionospheric Effects Research, Spacecraft Charging Technology; Meteorology Division--Cloud Physics, Ground-Based Remote-Sensing Techniques, Mesoscale Observing and Forecasting, Design Climatology, Aircraft Icing Program, Atmospheric Dynamics; Terrestrial Sciences Division--Geodesy and Gravity, Geokinetics; Optical Physics Division--Atmospheric Transmission, Remote Sensing, INfrared Background; and Appendices.

Ethics and Body Politics: Interdisciplinary Possibilities for Embodied Psychotherapeutic Practice and Research

ERIC Educational Resources Information Center

Allegranti, Beatrice

2011-01-01

Ethical approaches to practice and research in counselling and arts/psychotherapies demand an urgent attention to body politics. Bodies are not neutral; gender, sexuality, ethnicity and class are socio-political aspects that shape our mental, emotional and physical selves and inform our ethical values. Drawing from the author's embodied practice…

Recent results from WASA-at-COSY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hejny, V.

2010-12-28

WASA--a 4{pi} spectrometer for detection of charged and neutral particles--started operation at the cooler synchrotron COSY-Juelich in 2007. A number of experiments on meson production and decays have been carried out since then. The status of the analysis and preliminary results of some selected topics from the physics program are discussed.

Mother-Child Interactional Patterns in High- and Low-Risk Mothers.

ERIC Educational Resources Information Center

Dolz, Laura; Cerezo, M. Angeles; Milner, Joel S.

1997-01-01

A study of 10 high-risk (of child physical abuse) and 10 demographically similar low-risk Spanish mother-child dyads investigated interactional patterns in the home. High-risk mothers made fewer neutral approaches to their children, displayed more negative behaviors toward their children, and made more indiscriminate responses to their children's…

Pepsinogen D

PubMed Central

Lee, D.; Ryle, A. P.

1967-01-01

Methods are described for the isolation and purification of pepsinogen D, a minor zymogen occurring to the extent of about 5% of the potential proteolytic activity in neutral extracts of the pig gastric mucosa. The physical and chemical properties of this zymogen indicate that it is very similar to, if not identical with, dephosphopepsinogen. ImagesFig. 3. PMID:4167464

Viscosity of colloidal suspensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, E.G.D.; Schepper, I.M. de

Simple expressions are given for the effective Newtonian viscosity as a function of concentration as well as for the effective visco-elastic response as a function of concentration and imposed frequency, of monodisperse neutral colloidal suspensions over the entire fluid range. The basic physical mechanisms underlying these formulae are discussed. The agreement with existing experiments is very good.

Incoherent scatter radar observations of the ionosphere

NASA Technical Reports Server (NTRS)

Hagfors, Tor

1989-01-01

Incoherent scatter radar (ISR) has become the most powerful means of studying the ionosphere from the ground. Many of the ideas and methods underlying the troposphere and stratosphere (ST) radars have been taken over from ISR. Whereas the theory of refractive index fluctuations in the lower atmosphere, depending as it does on turbulence, is poorly understood, the theory of the refractivity fluctuations in the ionosphere, which depend on thermal fluctuations, is known in great detail. The underlying theory is one of the most successful theories in plasma physics, and allows for many detailed investigations of a number of parameters such as electron density, electron temperature, ion temperature, electron mean velocity, and ion mean velocity as well as parameters pertaining to composition, neutral density and others. Here, the author reviews the fundamental processes involved in the scattering from a plasma undergoing thermal or near thermal fluctuations in density. The fundamental scattering properties of the plasma to the physical parameters characterizing them from first principles. He does not discuss the observation process itself, as the observational principles are quite similar whether they are applied to a neutral gas or a fluctuating plasma.

Choosing the negative: A behavioral demonstration of morbid curiosity

PubMed Central

2017-01-01

This paper examined, with a behavioral paradigm, to what extent people choose to view stimuli that portray death, violence or harm. Based on briefly presented visual cues, participants made choices between highly arousing, negative images and positive or negative alternatives. The negative images displayed social scenes that involved death, violence or harm (e.g., war scene), or decontextualized, close-ups of physical harm (e.g., mutilated face) or natural threat (e.g., attacking shark). The results demonstrated that social negative images were chosen significantly more often than other negative categories. Furthermore, participants preferred social negative images over neutral images. Physical harm images and natural threat images were not preferred over neutral images, but were chosen in about thirty-five percent of the trials. These results were replicated across three different studies, including a study that presented verbal descriptions of images as pre-choice cues. Together, these results show that people deliberately subject themselves to negative images. With this, the present paper demonstrates a dynamic relationship between negative information and behavior and advances new insights into the phenomenon of morbid curiosity. PMID:28683147

Luminol modified polycarbazole and poly(o-anisidine): Theoretical insights compared with experimental data.

PubMed

Jadoun, Sapana; Verma, Anurakshee; Riaz, Ufana

2018-06-07

With the aim to explore the effect of luminol as a multifunctional dopant for conjugated polymers, the present study reports the ultrasound-assisted doping of polycarbazole (PCz) and poly(o-anisidine) (PAnis) with luminol in basic, acidic and neutral media. The synthesized homopolymers and luminol doped polymers were characterized using FT-IR, UV-visible and XRD studies while the photo-physical properties were investigated via fluorescence spectroscopy. Density functional theory (DFT) calculations were performed to get insights into the structural, optical, and electronic properties of homopolymers of polycarbazole (PCz) and poly(o-anisidine) (PAnis). Vibrational bands B3LYP/6-311G (d,p) level, UV-vis spectral bands and electronic properties such as ionization potentials (IP), electron affinities (EA) and HOMO-LUMO band gap energies of the homopolymers and doped polymers were calculated and compared. Results revealed that luminol doped polymers showed different photo-physical characteristics in acidic, basic and neutral media which could be tuned to obtain near infrared (NIR) emitting polymers. Copyright © 2018 Elsevier B.V. All rights reserved.

Women in the Physical Sciences in Sweden: Do We Have True Gender Equality in a ``Gender-Neutral'' Country?

NASA Astrophysics Data System (ADS)

Sorensen, Stacey L.; Rachlew, Elisabeth; Wiesner, Karoline; Engblom, Pia Thorngren

2005-10-01

Sweden, together with the other Nordic countries, seems at first glance to offer an environment where women and men enjoy equal treatment at all levels of society. Governments proclaim policies invoking gender-neutral regulations and legal frameworks. Government-supported parental leave programs provide paid leave for both parents, the child-care system is well developed, women are represented at high levels in the government, and educational levels are high. Clearly, awareness of gender issues and openness in the classroom and workplace must be very high. Why, then, is the career pipeline for women in physics leaking so badly? Why are there so few women in high-level management positions in industry? How can salaries for women on all levels, not least within the public sector, be consistently lower than for their male counterparts? What factors are important and how can we influence the situation so that women receive their fair share of power and recognition for their achievements? We discuss some of these issues, and describe the present situation in Sweden.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedman, A.; Barnard, J. J.; Cohen, R. H.

The Heavy Ion Fusion Science Virtual National Laboratory(a collaboration of LBNL, LLNL, and PPPL) is using intense ion beams to heat thin foils to the"warm dense matter" regime at<~;; 1 eV, and is developing capabilities for studying target physics relevant to ion-driven inertial fusion energy. The need for rapid target heating led to the development of plasma-neutralized pulse compression, with current amplification factors exceeding 50 now routine on the Neutralized Drift Compression Experiment (NDCX). Construction of an improved platform, NDCX-II, has begun at LBNL with planned completion in 2012. Using refurbished induction cells from the Advanced Test Accelerator at LLNL,more » NDCX-II will compress a ~;;500 ns pulse of Li+ ions to ~;;1 ns while accelerating it to 3-4 MeV over ~;;15 m. Strong space charge forces are incorporated into the machine design at a fundamental level. We are using analysis, an interactive 1D PIC code (ASP) with optimizing capabilities and centroid tracking, and multi-dimensional Warpcode PIC simulations, to develop the NDCX-II accelerator. This paper describes the computational models employed, and the resulting physics design for the accelerator.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedman, A; Barnard, J J; Cohen, R H

The Heavy Ion Fusion Science Virtual National Laboratory (a collaboration of LBNL, LLNL, and PPPL) is using intense ion beams to heat thin foils to the 'warm dense matter' regime at {approx}< 1 eV, and is developing capabilities for studying target physics relevant to ion-driven inertial fusion energy. The need for rapid target heating led to the development of plasma-neutralized pulse compression, with current amplification factors exceeding 50 now routine on the Neutralized Drift Compression Experiment (NDCX). Construction of an improved platform, NDCX-II, has begun at LBNL with planned completion in 2012. Using refurbished induction cells from the Advanced Testmore » Accelerator at LLNL, NDCX-II will compress a {approx}500 ns pulse of Li{sup +} ions to {approx} 1 ns while accelerating it to 3-4 MeV over {approx} 15 m. Strong space charge forces are incorporated into the machine design at a fundamental level. We are using analysis, an interactive 1D PIC code (ASP) with optimizing capabilities and centroid tracking, and multi-dimensional Warpcode PIC simulations, to develop the NDCX-II accelerator. This paper describes the computational models employed, and the resulting physics design for the accelerator.« less

Sub-diffusion and trapped dynamics of neutral and charged probes in DNA-protein coacervates

NASA Astrophysics Data System (ADS)

Arfin, Najmul; Yadav, Avinash Chand; Bohidar, H. B.

2013-11-01

The physical mechanism leading to the formation of large intermolecular DNA-protein complexes has been studied. Our study aims to explain the occurrence of fast coacervation dynamics at the charge neutralization point, followed by the appearance of smaller complexes and slower coacervation dynamics as the complex experiences overcharging. Furthermore, the electrostatic potential and probe mobility was investigated to mimic the transport of DNA / DNA-protein complex in a DNA-protein complex coacervate medium [N. Arfin and H. B. Bohidar, J. Phys. Chem. B 116, 13192 (2012)] by assigning neutral, negative, or positive charge to the probe particle. The mobility of the neutral probe was maximal at low matrix concentrations and showed random walk behavior, while its mobility ceased at the jamming concentration of c = 0.6, showing sub-diffusion and trapped dynamics. The positively charged probe showed sub-diffusive random walk followed by trapped dynamics, while the negatively charged probe showed trapping with occasional hopping dynamics at much lower concentrations. Sub-diffusion of the probe was observed in all cases under consideration, where the electrostatic interaction was used exclusively as the dominant force involved in the dynamics. For neutral and positive probes, the mean square displacement ⟨R2⟩ exhibits a scaling with time as ⟨R2⟩ ˜ tα, distinguishing random walk and trapped dynamics at α = 0.64 ± 0.04 at c = 0.12 and c = 0.6, respectively. In addition, the same scaling factors with the exponent β = 0.64 ± 0.04 can be used to distinguish random walk and trapped dynamics for the neutral and positive probes using the relation between the number of distinct sites visited by the probe, S(t), which follows the scaling, S(t) ˜ tβ/ln (t). Our results established the occurrence of a hierarchy of diffusion dynamics experienced by a probe in a dense medium that is either charged or neutral.

The Flostation - an Immersive Cyberspace System

NASA Technical Reports Server (NTRS)

Park, Brian

2006-01-01

A flostation is a computer-controlled apparatus that, along with one or more computer(s) and other computer-controlled equipment, is part of an immersive cyberspace system. The system is said to be immersive in two senses of the word: (1) It supports the body in a modified form neutral posture experienced in zero gravity and (2) it is equipped with computer-controlled display equipment that helps to give the occupant of the chair a feeling of immersion in an environment that the system is designed to simulate. Neutral immersion was conceived during the Gemini program as a means of training astronauts for working in a zerogravity environment. Current derivatives include neutral-buoyancy tanks and the KC-135 airplane, each of which mimics the effects of zero gravity. While these have performed well in simulating the shorter-duration flights typical of the space program to date, a training device that can take astronauts to the next level will be needed for simulating longer-duration flights such as that of the International Space Station. The flostation is expected to satisfy this need. The flostation could also be adapted and replicated for use in commercial ventures ranging from home entertainment to medical treatment. The use of neutral immersion in the flostation enables the occupant to recline in an optimal posture of rest and meditation. This posture, combines savasana (known to practitioners of yoga) and a modified form of the neutral posture assumed by astronauts in outer space. As the occupant relaxes, awareness of the physical body is reduced. The neutral body posture, which can be maintained for hours without discomfort, is extended to the eyes, ears, and hands. The occupant can be surrounded with a full-field-of-view visual display and nearphone sound, and can be stimulated with full-body vibration and motion cueing. Once fully immersed, the occupant can use neutral hand controllers (that is, hand-posture sensors) to control various aspects of the simulated environment.

Metals and dust in the neutral ISM: the Galaxy, Magellanic Clouds, and damped Lyman-α absorbers

NASA Astrophysics Data System (ADS)

De Cia, Annalisa

2018-05-01

Context. The presence of dust in the neutral interstellar medium (ISM) dramatically changes the metal abundances that we measure. Understanding the metal content in the neutral ISM, and a direct comparison between different environments, has been hampered to date because of the degeneracy to the observed ISM abundances caused by the effects of metallicity, the presence of dust, and nucleosynthesis. Aims: We study the metal and dust content in the neutral ISM consistently in different environments, and assess the universality of recently discovered sequences of relative abundances. We also intend to assess the validity of [Zn/Fe] as a tracer of dust in the ISM. This has recently been cast into doubt based on observations of stellar abundances, and needs to be addressed before we can safely use it to study the ISM. Methods: In this letter we present a simple comparison of relative abundances observed in the neutral ISM in the Galaxy, the Magellanic Clouds, and damped Lyman-α absorbers (DLAs). The main novelty in this comparison is the inclusion of the Magellanic Clouds. Results: The same sequences of relative abundances are valid for the Galaxy, Magellanic Clouds, and DLAs. These sequences are driven by the presence of dust in the ISM and seem "universal". Conclusions: The metal and dust properties in the neutral ISM appear to follow a similar behaviour in different environments. This suggests that a dominant fraction of the dust budget is built up from grain growth in the ISM depending of the physical conditions and regardless of the star formation history of the system. In addition, the DLA gas behaves like the neutral ISM, at least from a chemical point of view. Finally, despite the deviations in [Zn/Fe] observed in stellar abundances, [Zn/Fe] is a robust dust tracer in the ISM of different environments, from the Galaxy to DLAs.

$$B^0_{(s)}$$-mixing matrix elements from lattice QCD for the Standard Model and beyond

DOE PAGES

Bazavov, A.; Bernard, C.; Bouchard, C. M.; ...

2016-06-28

We calculate—for the first time in three-flavor lattice QCD—the hadronic matrix elements of all five local operators that contribute to neutral B 0- and B s-meson mixing in and beyond the Standard Model. We present a complete error budget for each matrix element and also provide the full set of correlations among the matrix elements. We also present the corresponding bag parameters and their correlations, as well as specific combinations of the mixing matrix elements that enter the expression for the neutral B-meson width difference. We obtain the most precise determination to date of the SU(3)-breaking ratio ξ=1.206(18)(6), where themore » second error stems from the omission of charm-sea quarks, while the first encompasses all other uncertainties. The threefold reduction in total uncertainty, relative to the 2013 Flavor Lattice Averaging Group results, tightens the constraint from B mixing on the Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle. Our calculation employs gauge-field ensembles generated by the MILC Collaboration with four lattice spacings and pion masses close to the physical value. We use the asqtad-improved staggered action for the light-valence quarks and the Fermilab method for the bottom quark. We use heavy-light meson chiral perturbation theory modified to include lattice-spacing effects to extrapolate the five matrix elements to the physical point. We combine our results with experimental measurements of the neutral B-meson oscillation frequencies to determine the CKM matrix elements |V td| = 8.00(34)(8)×10 -3, |V ts| = 39.0(1.2)(0.4)×10 -3, and |V td/V ts| = 0.2052(31)(10), which differ from CKM-unitarity expectations by about 2σ. In addition, these results and others from flavor-changing-neutral currents point towards an emerging tension between weak processes that are mediated at the loop and tree levels.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazavov, A.; Bernard, C.; Bouchard, C. M.

We calculate—for the first time in three-flavor lattice QCD—the hadronic matrix elements of all five local operators that contribute to neutral B 0- and B s-meson mixing in and beyond the Standard Model. We present a complete error budget for each matrix element and also provide the full set of correlations among the matrix elements. We also present the corresponding bag parameters and their correlations, as well as specific combinations of the mixing matrix elements that enter the expression for the neutral B-meson width difference. We obtain the most precise determination to date of the SU(3)-breaking ratio ξ=1.206(18)(6), where themore » second error stems from the omission of charm-sea quarks, while the first encompasses all other uncertainties. The threefold reduction in total uncertainty, relative to the 2013 Flavor Lattice Averaging Group results, tightens the constraint from B mixing on the Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle. Our calculation employs gauge-field ensembles generated by the MILC Collaboration with four lattice spacings and pion masses close to the physical value. We use the asqtad-improved staggered action for the light-valence quarks and the Fermilab method for the bottom quark. We use heavy-light meson chiral perturbation theory modified to include lattice-spacing effects to extrapolate the five matrix elements to the physical point. We combine our results with experimental measurements of the neutral B-meson oscillation frequencies to determine the CKM matrix elements |V td| = 8.00(34)(8)×10 -3, |V ts| = 39.0(1.2)(0.4)×10 -3, and |V td/V ts| = 0.2052(31)(10), which differ from CKM-unitarity expectations by about 2σ. In addition, these results and others from flavor-changing-neutral currents point towards an emerging tension between weak processes that are mediated at the loop and tree levels.« less

Plasma Flowfields Around Low Earth Orbit Objects: Aerodynamics to Underpin Orbit Predictions

NASA Astrophysics Data System (ADS)

Capon, Christopher; Boyce, Russell; Brown, Melrose

2016-07-01

Interactions between orbiting bodies and the charged space environment are complex. The large variation in passive body parameters e.g. size, geometry and materials, makes the plasma-body interaction in Low Earth Orbit (LEO) a region rich in fundamental physical phenomena. The aerodynamic interaction of LEO orbiting bodies with the neutral environment constitutes the largest non-conservative force on the body. However in general, study of the LEO plasma-body interaction has not been concerned with external flow physics, but rather with the effects on surface charging. The impact of ionospheric flow physics on the forces on space debris (and active objects) is not well understood. The work presented here investigates the contribution that plasma-body interactions have on the flow structure and hence on the total atmospheric force vector experienced by a polar orbiting LEO body. This work applies a hybrid Particle-in-Cell (PIC) - Direct Simulation Monte Carlo (DSMC) code, pdFoam, to self-consistently model the electrostatic flowfield about a cylinder with a uniform, fixed surface potential. Flow conditions are representative of the mean conditions experienced by the Earth Observing Satellite (EOS) based on the International Reference Ionosphere model (IRI-86). The electron distribution function is represented by a non-linear Boltzmann electron fluid and ion gas-surface interactions are assumed to be that of a neutralising, conducting, thermally accommodating solid wall with diffuse reflections. The variation in flowfield and aerodynamic properties with surface potential at a fixed flow condition is investigated, and insight into the relative contributions of charged and neutral species to the flow physics experienced by a LEO orbiting body is provided. This in turn is intended to help improve the fidelity of physics-based orbit predictions for space debris and other near-Earth space objects.

Copernicus observations of distant unreddened stars. I. Line of sight to MU Colombae and HD 28497

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shull, J.M.; York, D.G.

1977-02-01

Copernicus UV data on interstellar lines toward ..mu.. Col and HD 28497 are analyzed to study the abundances and physical conditions in the many components found in each line of sight. Despite low mean neutral hydrogen densities toward these stars, a substantial portion of the neutral gas is associated with dense condensations containing H/sub 2/. In several high-velocity components, Fe, Ca, and possibly Si appear to be nearer their cosmic abundances than is typical in interstellar gas; this effect may be related to the correlation of N (Ca II)/N (Na I) with cloud velocity, and suggests a grain-disruption model. Low-velocitymore » ionized gas with n/sub e/=0.1 to 0.3 cm/sup -3/ appears to be associated with an extended H II region near ..mu.. Col; ionized gas of similar density is seen at the same velocities as the four neutral components toward HD 28497. Si III absorption, with a wide profile at high negative velocities, unaccompanied by any detectable Si II, N II, or neutral gas, is reported in both stars. The observed Si III column densities and velocity fields may be explained by collisionally ionized gas at 30,000 to 100,000 K behind radiatively cooling strong shocks.« less

A self-consistent view on plasma-neutral interaction near a wall: plasma acceleration by momentum removal and heating by cold walls

NASA Astrophysics Data System (ADS)

van Rooij, Gerard; den Harder, Niek; Minea, Teofil; Shumack, Amy; de Blank, H.; Plasma Physics Team

2014-10-01

In plasma physics, material walls are generally regarded as perfect sinks for charged particles and their energy. A special case arises when the wall efficiently reflects the neutralized plasma particles (with a significant portion of their kinetic energy) and at the same time the upstream plasma is of sufficiently high density to yield strong neutral-ion coupling (i.e. reflected energy and momentum will not escape from the plasma). Under these conditions, plasma-surface interaction will feedback to the upstream plasma and a self-consistent view on the coupling between plasma and neutrals is required for correct prediction of plasma conditions and plasma-surface interaction. Here, an analytical and numerical study of the fluid equations is combined with experiments (in hydrogen and argon) to construct such a self-consistent view. It shows how plasma momentum removal builds up upstream pressure and causes plasma acceleration towards the wall. It also shows how energy reflection causes plasma heating, which recycles part of the reflected power to the wall and induces additional flow acceleration due to local sound speed increase. The findings are relevant as generic textbook example and are at play in the boundary plasma of fusion devices.

Comparisons between tokamak fueling of gas puffing and supersonic molecular beam injection in 2D simulations

DOE PAGES

Zhou, Y. L.; Wang, Z. H.; Xu, X. Q.; ...

2015-01-09

Plasma fueling with high efficiency and deep injection is very important to enable fusion power performance requirements. It is a powerful and efficient way to study neutral transport dynamics and find methods of improving the fueling performance by doing large scale simulations. Furthermore, two basic fueling methods, gas puffing (GP) and supersonic molecular beam injection (SMBI), are simulated and compared in realistic divertor geometry of the HL-2A tokamak with a newly developed module, named trans-neut, within the framework of BOUT++ boundary plasma turbulence code [Z. H. Wang et al., Nucl. Fusion 54, 043019 (2014)]. The physical model includes plasma density,more » heat and momentum transport equations along with neutral density, and momentum transport equations. In transport dynamics and profile evolutions of both plasma and neutrals are simulated and compared between GP and SMBI in both poloidal and radial directions, which are quite different from one and the other. It finds that the neutrals can penetrate about four centimeters inside the last closed (magnetic) flux surface during SMBI, while they are all deposited outside of the LCF during GP. Moreover, it is the radial convection and larger inflowing flux which lead to the deeper penetration depth of SMBI and higher fueling efficiency compared to GP.« less

Comparisons between tokamak fueling of gas puffing and supersonic molecular beam injection in 2D simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Y. L.; Wang, Z. H.; Xu, X. Q.

Plasma fueling with high efficiency and deep injection is very important to enable fusion power performance requirements. It is a powerful and efficient way to study neutral transport dynamics and find methods of improving the fueling performance by doing large scale simulations. Furthermore, two basic fueling methods, gas puffing (GP) and supersonic molecular beam injection (SMBI), are simulated and compared in realistic divertor geometry of the HL-2A tokamak with a newly developed module, named trans-neut, within the framework of BOUT++ boundary plasma turbulence code [Z. H. Wang et al., Nucl. Fusion 54, 043019 (2014)]. The physical model includes plasma density,more » heat and momentum transport equations along with neutral density, and momentum transport equations. In transport dynamics and profile evolutions of both plasma and neutrals are simulated and compared between GP and SMBI in both poloidal and radial directions, which are quite different from one and the other. It finds that the neutrals can penetrate about four centimeters inside the last closed (magnetic) flux surface during SMBI, while they are all deposited outside of the LCF during GP. Moreover, it is the radial convection and larger inflowing flux which lead to the deeper penetration depth of SMBI and higher fueling efficiency compared to GP.« less

Comparisons between tokamak fueling of gas puffing and supersonic molecular beam injection in 2D simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Y. L.; Southwestern Institute of Physics, Chengdu 610041; Wang, Z. H., E-mail: zhwang@swip.ac.cn

Plasma fueling with high efficiency and deep injection is very important to enable fusion power performance requirements. It is a powerful and efficient way to study neutral transport dynamics and find methods of improving the fueling performance by doing large scale simulations. Two basic fueling methods, gas puffing (GP) and supersonic molecular beam injection (SMBI), are simulated and compared in realistic divertor geometry of the HL-2A tokamak with a newly developed module, named trans-neut, within the framework of BOUT++ boundary plasma turbulence code [Z. H. Wang et al., Nucl. Fusion 54, 043019 (2014)]. The physical model includes plasma density, heatmore » and momentum transport equations along with neutral density, and momentum transport equations. Transport dynamics and profile evolutions of both plasma and neutrals are simulated and compared between GP and SMBI in both poloidal and radial directions, which are quite different from one and the other. It finds that the neutrals can penetrate about four centimeters inside the last closed (magnetic) flux surface during SMBI, while they are all deposited outside of the LCF during GP. It is the radial convection and larger inflowing flux which lead to the deeper penetration depth of SMBI and higher fueling efficiency compared to GP.« less

Efficient Coupling of Fluid-Plasma and Monte-Carlo-Neutrals Models for Edge Plasma Transport

NASA Astrophysics Data System (ADS)

Dimits, A. M.; Cohen, B. I.; Friedman, A.; Joseph, I.; Lodestro, L. L.; Rensink, M. E.; Rognlien, T. D.; Sjogreen, B.; Stotler, D. P.; Umansky, M. V.

2017-10-01

UEDGE has been valuable for modeling transport in the tokamak edge and scrape-off layer due in part to its efficient fully implicit solution of coupled fluid neutrals and plasma models. We are developing an implicit coupling of the kinetic Monte-Carlo (MC) code DEGAS-2, as the neutrals model component, to the UEDGE plasma component, based on an extension of the Jacobian-free Newton-Krylov (JFNK) method to MC residuals. The coupling components build on the methods and coding already present in UEDGE. For the linear Krylov iterations, a procedure has been developed to ``extract'' a good preconditioner from that of UEDGE. This preconditioner may also be used to greatly accelerate the convergence rate of a relaxed fixed-point iteration, which may provide a useful ``intermediate'' algorithm. The JFNK method also requires calculation of Jacobian-vector products, for which any finite-difference procedure is inaccurate when a MC component is present. A semi-analytical procedure that retains the standard MC accuracy and fully kinetic neutrals physics is therefore being developed. Prepared for US DOE by LLNL under Contract DE-AC52-07NA27344 and LDRD project 15-ERD-059, by PPPL under Contract DE-AC02-09CH11466, and supported in part by the U.S. DOE, OFES.

Transport in a field aligned magnetized plasma/neutral gas boundary: the end of the plasma

NASA Astrophysics Data System (ADS)

Cooper, Christopher Michael

The objective of this dissertation is to characterize the physics of a boundary layer between a magnetized plasma and a neutral gas along the direction of a confining magnetic field. A series of experiments are performed at the Enormous Toroidal Plasma Device (ETPD) at UCLA to study this field aligned Neutral Boundary Layer (NBL) at the end of the plasma. A Lanthanum Hexaboride (LaB6) cathode and semi-transparent anode creates a magnetized, current-free helium plasma which terminates on a neutral helium gas without touching any walls. Probes are inserted into the plasma to measure the basic plasma parameters and study the transport in the NBL. The experiment is performed in the weakly ionized limit where the plasma density (ne) is much less than the neutral density (nn) such that ne/nn < 5%. The NBL is characterized by a field-aligned electric field which begins at the point where the plasma pressure equilibrates with the neutral gas pressure. Beyond the pressure equilibration point the electrons and ions lose their momentum by collisions with the neutral gas and come to rest. An electric field is established self consistently to maintain a current-free termination through equilibration of the different species' stopping rates in the neutral gas. The electric field resembles a collisional quasineutral sheath with a length 10 times the electron-ion collision length, 100 times the neutral collision length, and 10,000 times the Debye length. Collisions with the neutral gas dominate the losses in the system. The measured plasma density loss rates are above the classical cross-field current-free ambipolar rate, but below the anomalous Bohm diffusion rate. The electron temperature is below the ionization threshold of the gas, 2.2 eV in helium. The ions are in thermal equilibrium with the neutral gas. A generalized theory of plasma termination in a Neutral Boundary Layer is applied to this case using a two-fluid, current-free, weakly ionized transport model. The electron and ion momentum equations along the field are combined in a generalized Ohm's law which predicts the axial electric field required to maintain a current-free termination. The pressure balance criteria for termination and the predicted electric field are confirmed over a scaling of plasma parameters. The experiment and the model are relevant for studying NBLs in other systems, such as the atmospheric termination of the aurora or detached gaseous divertors. A steady state modified ambipolar system is measured in the ETPD NBL. The drift speeds associated with these currents are a small fraction of the plasma flow speeds and the problem is treated as a perturbation to the termination model. The current-free condition on the model is relaxed to explain the presence of the divergence free current.

Astrochemistry: Recent Advances in the Study of Carbon Molecules in Space

NASA Technical Reports Server (NTRS)

Salama, Farid

2006-01-01

Carbon molecules and ions play an important role in space. Polycyclic Aromatic Hydrocarbons (PAHs) are the best-known candidates to account for the infrared emission bands (UIR bands) and PAH spectral features are now being used as probes of the interstellar medium in Galactic and extra-galactic environments. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory Astrochemistry is to reproduce (in a realistic way) the physical conditions that exist in the emission and absorption interstellar zones. An extensive laboratory program has been developed in various laboratories to characterize the physical and chemical properties of PAHs in astrophysical environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. In particular, laboratory experiments provide measurements of the spectral characteristics of interstellar PAH analogs from the ultraviolet and visible range to the infrared range for comparison with astronomical data. The harsh physical conditions of the interstellar medium - characterized by a low temperature, an absence of collisions and strong ultraviolet radiation fields - are simulated in the laboratory by associating a molecular beam with an ionizing discharge to generate a cold plasma expansion. PAH ions are formed from the neutral precursors in an isolated environment at low temperature (of the order of 100 K). The spectra of neutral and ionized PAHs are measured using the high sensitivity methods of cavity ring down spectroscopy (CRDS). These experiments provide unique information on the spectra of free, cold large carbon molecules and ions in the gas phase.

The Myth of Gender Neutrality

NASA Astrophysics Data System (ADS)

Dancy, Melissa

2004-09-01

It is well known that women are underrepresented in physics. The prevailing view is that there is a "leaky pipeline" of female physicists which has lead to a focus on providing mentors and increasing the opportunity for girls to experience science. The assumption is that the numbers of women in physics can be increased by integrating women into the existing structure. Although it may seem reasonable, women are making only small gains in participation levels. In this paper, I explore the idea that there is no leaky pipeline. Rather, the environment is fundamentally "male" and women will never be equally represented until fundamental changes are made in both our educational system and in the cultural assumptions of our physics community.

Experiments with bosonic atoms for quantum gas assembly

NASA Astrophysics Data System (ADS)

Brown, Mark; Lin, Yiheng; Lester, Brian; Kaufman, Adam; Ball, Randall; Brossard, Ludovic; Isaev, Leonid; Thiele, Tobias; Lewis-Swan, Robert; Schymik, Kai-Niklas; Rey, Ana Maria; Regal, Cindy

2017-04-01

Quantum gas assembly is a promising platform for preparing and observing neutral atom systems on the single-atom level. We have developed a toolbox that includes ground-state laser cooling, high-fidelity loading techniques, addressable spin control, and dynamic spatial control and coupling of atoms. Already, this platform has enabled us to pursue a number of experiments studying entanglement and interference of pairs of bosonic atoms. We discuss our recent work in probabilistically entangling neutral atoms via interference, measurement, and post-selection as well as our future pursuits of interesting spin-motion dynamics of larger arrays of atoms. This work was supported by the David and Lucile Packard Foundation, National Science Foundation Physics Frontier Centers, and the National Defense Science and Engineering Graduate Fellowships program.

Heavy Higgs searches: flavour matters

NASA Astrophysics Data System (ADS)

Gori, Stefania; Grojean, Christophe; Juste, Aurelio; Paul, Ayan

2018-01-01

We point out that the stringent lower bounds on the masses of additional electrically neutral and charged Higgs bosons crucially depend on the flavour structure of their Yukawa interactions. We show that these bounds can easily be evaded by the introduction of flavour-changing neutral currents in the Higgs sector. As an illustration, we study the phenomenology of a two Higgs doublet model with a Yukawa texture singling out the third family of quarks and leptons. We combine constraints from low-energy flavour physics measurements, LHC measurements of the 125 GeV Higgs boson rates, and LHC searches for new heavy Higgs bosons. We propose novel LHC searches that could be performed in the coming years to unravel the existence of these new Higgs bosons.

MAIMIK: A high current electron beam experiment on a sounding rocket from Andoya rocket range (Norway)

NASA Astrophysics Data System (ADS)

Maehlum, B. N.; Denig, W. F.; Egeland, A. A.; Friedrich, M.; Hansen, T.; Holmgren, G. K.; Maaseide, K.; Maynard, N. C.; Narheim, B. T.; Svenes, K.

1987-08-01

Two payloads (mother-daughter) connected by a tether were launched by sounding rocket to study the interactions between the electron beam and the environment for various boundary conditions and to study the physical processes associated with the neutralization of electrically charged vehicles in an ionospheric plasma. The daughter payload carried an accelerator which emitted pulses of electrons of 8 keV energies. The rocket instruments and results related to vehicle charging and neutralization are summarized. Results indicate extremely high charging of the daughter (several kV) for beam current greater than or = 80 mA. The reason may be the low plasma density (10 billion/cu m) in the F region during the experiment.

Measurements with magnetic field in the National Spherical Torus Experiment using the motional Stark effect with laser induced fluorescence diagnostic

NASA Astrophysics Data System (ADS)

Foley, E. L.; Levinton, F. M.

2013-04-01

The motional Stark effect with laser-induced fluorescence diagnostic (MSE-LIF) has been installed and tested on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Lab. The MSE-LIF diagnostic will be capable of measuring radially resolved profiles of magnetic field magnitude or pitch angle in NSTX plasmas. The system includes a diagnostic neutral hydrogen beam and a laser which excites the n = 2 to n = 3 transition. A viewing system has been implemented which will support up to 38 channels from the plasma edge to past the magnetic axis. First measurements of MSE-LIF signals in the presence of small applied magnetic fields in neutral gas are reported.

Search for the flavor-changing neutral-current decay t-->Zq in pp collisions at sqrt[s] = 1.96 TeV.

PubMed

Aaltonen, T; Adelman, J; Akimoto, T; Albrow, M G; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzurri, P; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Bednar, P; Beecher, D; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Beringer, J; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Calancha, C; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Copic, K; Cordelli, M; Cortiana, G; Cox, D J; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; De Cecco, S; Deisher, A; De Lorenzo, G; Dell'Orso, M; Deluca, C; Demortier, L; Deng, J; Deninno, M; Derwent, P F; di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Elagin, A; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; Genser, K; Gerberich, H; Gerdes, D; Gessler, A; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jayatilaka, B; Jeon, E J; Jha, M K; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Knuteson, B; Ko, B R; Koay, S A; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhr, T; Kulkarni, N P; Kurata, M; Kusakabe, Y; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, E; Lee, S W; Leone, S; Lewis, J D; Lin, C S; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lovas, L; Lu, R-S; Lucchesi, D; Lueck, J; Luci, C; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzione, A; Merkel, P; Mesropian, C; Miao, T; Miladinovic, N; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moggi, N; Moon, C S; Moore, R; Morello, M J; Morlok, J; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Osterberg, K; Griso, S Pagan; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Pueschel, E; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Saltó, O; Saltzberg, D; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, A; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shiraishi, S; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spreitzer, T; Squillacioti, P; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sutherland, M; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thompson, G A; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Tourneur, S; Tu, Y; Turini, N; Ukegawa, F; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner-Kuhr, J; Wagner, W; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zheng, Y; Zucchelli, S

2008-11-07

We report a search for the flavor-changing neutral-current decay of the top quark t-->Zq (q=u, c) in pp collisions at sqrt[s]=1.96 TeV using a data sample corresponding to an integrated luminosity of 1.9 fb(-1) collected by the CDF II detector. This decay is strongly suppressed in the standard model and an observation of a signal at the Fermilab Tevatron would be an indication of physics beyond the standard model. Using Z+ > or = 4 jet final state candidate events, with and without an identified bottom quark jet, we obtain an upper limit of B(t-->Zq) < 3.7% at 95% C.L.

Mixed stack charge transfer crystals: Crossing the neutral-ionic borderline by chemical substitution

NASA Astrophysics Data System (ADS)

Castagnetti, Nicola; Masino, Matteo; Rizzoli, Corrado; Girlando, Alberto; Rovira, Concepció

2018-02-01

We report extensive structural and spectroscopic characterization of four mixed stack charge-transfer (ms-CT) crystals formed by the electron donor 3,3',5 ,5' -tetramethylbenzidine (TMB) with Chloranil (CA), Bromanil (BA), 2,5-difluoro-tetracyanoquinodimethane (TCNQF2), and tetrafluoro-tetracyanoquinodimethane (TCNQF4). Together with the separately studied TMB-TCNQ [Phys. Rev. B 95, 024101 (2017), 10.1103/PhysRevB.95.024101] the TMB-acceptor series spans a wide range of degree of CT, from about 0.14 to 0.91, crossing the neutral-ionic interface, yet retaining similar packing and donor-acceptor CT integrals. First principle calculations of key phenomenological parameters allow us to get insight into the factors determining the degree of CT and other relevant physical properties.

Enhancing the Benefits of Written Emotional Disclosure through Response Training

PubMed Central

Konig, Andrea; Eonta, Alison; Dyal, Stephanie R.; Vrana, Scott R.

2014-01-01

Writing about a personal stressful event has been found to have psychological and physical health benefits, especially when physiological response increases during writing. Response training was developed to amplify appropriate physiological reactivity in imagery exposure. The present study examined whether response training enhances the benefits of written emotional disclosure. Participants were assigned to either a written emotional disclosure condition (n = 113) or a neutral writing condition (n = 133). Participants in each condition wrote for 20 minutes on three occasions and received response training (n = 79), stimulus training (n = 84) or no training (n = 83). Heart rate and skin conductance were recorded throughout a 10-minute baseline, 20-minute writing, and a 10-minute recovery period. Self-reported emotion was assessed in each session. One month after completing the sessions, participants completed follow-up assessments of psychological and physical health outcomes. Emotional disclosure elicited greater physiological reactivity and self-reported emotion than neutral writing. Response training amplified physiological reactivity to emotional disclosure. Greater heart rate during emotional disclosure was associated with the greatest reductions in event-related distress, depression, and physical illness symptoms at follow-up, especially among response trained participants. Results support an exposure explanation of emotional disclosure effects and are the first to demonstrate that response training facilitates emotional processing and may be a beneficial adjunct to written emotional disclosure. PMID:24680230

Enhancing the benefits of written emotional disclosure through response training.

PubMed

Konig, Andrea; Eonta, Alison; Dyal, Stephanie R; Vrana, Scott R

2014-05-01

Writing about a personal stressful event has been found to have psychological and physical health benefits, especially when physiological response increases during writing. Response training was developed to amplify appropriate physiological reactivity in imagery exposure. The present study examined whether response training enhances the benefits of written emotional disclosure. Participants were assigned to either a written emotional disclosure condition (n=113) or a neutral writing condition (n=133). Participants in each condition wrote for 20 minutes on 3 occasions and received response training (n=79), stimulus training (n=84) or no training (n=83). Heart rate and skin conductance were recorded throughout a 10-minute baseline, 20-minute writing, and a 10-minute recovery period. Self-reported emotion was assessed in each session. One month after completing the sessions, participants completed follow-up assessments of psychological and physical health outcomes. Emotional disclosure elicited greater physiological reactivity and self-reported emotion than neutral writing. Response training amplified physiological reactivity to emotional disclosure. Greater heart rate during emotional disclosure was associated with the greatest reductions in event-related distress, depression, and physical illness symptoms at follow-up, especially among response trained participants. Results support an exposure explanation of emotional disclosure effects and are the first to demonstrate that response training facilitates emotional processing and may be a beneficial adjunct to written emotional disclosure. Copyright © 2014. Published by Elsevier Ltd.

Young Children's Curiosity about Physical Differences Associated with Race: Shared Reading to Encourage Conversation

ERIC Educational Resources Information Center

Kemple, Kristen M.; Lee, Rang, II.; Harris, Michelle

2016-01-01

Many have called for re-examination of the "colorblind" philosophy to which some early educators have, tacitly or explicitly, adhered (e.g. Boutte et al. 2011; Derman-Sparks and Edwards 2010; Husband 2012). It has been argued that, while colorblind approaches may appear to be politically neutral, they actually exacerbate racial…

Detection of Emotional Faces: Salient Physical Features Guide Effective Visual Search

ERIC Educational Resources Information Center

Calvo, Manuel G.; Nummenmaa, Lauri

2008-01-01

In this study, the authors investigated how salient visual features capture attention and facilitate detection of emotional facial expressions. In a visual search task, a target emotional face (happy, disgusted, fearful, angry, sad, or surprised) was presented in an array of neutral faces. Faster detection of happy and, to a lesser extent,…

Hydroxycarboxylic acids and salts

DOEpatents

Kiely, Donald E; Hash, Kirk R; Kramer-Presta, Kylie; Smith, Tyler N

2015-02-24

Compositions which inhibit corrosion and alter the physical properties of concrete (admixtures) are prepared from salt mixtures of hydroxycarboxylic acids, carboxylic acids, and nitric acid. The salt mixtures are prepared by neutralizing acid product mixtures from the oxidation of polyols using nitric acid and oxygen as the oxidizing agents. Nitric acid is removed from the hydroxycarboxylic acids by evaporation and diffusion dialysis.

Knowledge Is Something We Do: Knowing and Learning in Globally Networked Communities.

ERIC Educational Resources Information Center

Farell, Lesley; Holkner, Bernard

Workspaces are sites of contention over what is knowledge and who can say so; work-related education has never been a neutral arbiter. In a context in which workspaces routinely bring together physical place and cyber place in communication networks, traditional struggles over knowledge and knowing are affected by communications technologies (CT)…

ALCBEAM - Neutral beam formation and propagation code for beam-based plasma diagnostics

NASA Astrophysics Data System (ADS)

Bespamyatnov, I. O.; Rowan, W. L.; Liao, K. T.

2012-03-01

ALCBEAM is a new three-dimensional neutral beam formation and propagation code. It was developed to support the beam-based diagnostics installed on the Alcator C-Mod tokamak. The purpose of the code is to provide reliable estimates of the local beam equilibrium parameters: such as beam energy fractions, density profiles and excitation populations. The code effectively unifies the ion beam formation, extraction and neutralization processes with beam attenuation and excitation in plasma and neutral gas and beam stopping by the beam apertures. This paper describes the physical processes interpreted and utilized by the code, along with exploited computational methods. The description is concluded by an example simulation of beam penetration into plasma of Alcator C-Mod. The code is successfully being used in Alcator C-Mod tokamak and expected to be valuable in the support of beam-based diagnostics in most other tokamak environments. Program summaryProgram title: ALCBEAM Catalogue identifier: AEKU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKU_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 66 459 No. of bytes in distributed program, including test data, etc.: 7 841 051 Distribution format: tar.gz Programming language: IDL Computer: Workstation, PC Operating system: Linux RAM: 1 GB Classification: 19.2 Nature of problem: Neutral beams are commonly used to heat and/or diagnose high-temperature magnetically-confined laboratory plasmas. An accurate neutral beam characterization is required for beam-based measurements of plasma properties. Beam parameters such as density distribution, energy composition, and atomic excited populations of the beam atoms need to be known. Solution method: A neutral beam is initially formed as an ion beam which is extracted from the ion source by high voltage applied to the extraction and accelerating grids. The current distribution of a single beamlet emitted from a single pore of IOS depends on the shape of the plasma boundary in the emission region. Total beam extracted by IOS is calculated at every point of 3D mesh as sum of all contributions from each grid pore. The code effectively unifies the ion beam formation, extraction and neutralization processes with neutral beam attenuation and excitation in plasma and neutral gas and beam stopping by the beam apertures. Running time: 10 min for a standard run.

A single bout of resistance exercise can enhance episodic memory performance.

PubMed

Weinberg, Lisa; Hasni, Anita; Shinohara, Minoru; Duarte, Audrey

2014-11-01

Acute aerobic exercise can be beneficial to episodic memory. This benefit may occur because exercise produces a similar physiological response as physical stressors. When administered during consolidation, acute stress, both physical and psychological, consistently enhances episodic memory, particularly memory for emotional materials. Here we investigated whether a single bout of resistance exercise performed during consolidation can produce episodic memory benefits 48 h later. We used a one-leg knee extension/flexion task for the resistance exercise. To assess the physiological response to the exercise, we measured salivary alpha amylase (a biomarker of central norepinephrine), heart rate, and blood pressure. To test emotional episodic memory, we used a remember-know recognition memory paradigm with equal numbers of positive, negative, and neutral IAPS images as stimuli. The group that performed the exercise, the active group, had higher overall recognition accuracy than the group that did not exercise, the passive group. We found a robust effect of valence across groups, with better performance on emotional items as compared to neutral items and no difference between positive and negative items. This effect changed based on the physiological response to the exercise. Within the active group, participants with a high physiological response to the exercise were impaired for neutral items as compared to participants with a low physiological response to the exercise. Our results demonstrate that a single bout of resistance exercise performed during consolidation can enhance episodic memory and that the effect of valence on memory depends on the physiological response to the exercise. Copyright © 2014 Elsevier B.V. All rights reserved.

Carpal Tunnel Syndrome: Effectiveness of Physical Therapy and Electrophysical Modalities. An Updated Systematic Review of Randomized Controlled Trials.

PubMed

Huisstede, Bionka M; Hoogvliet, Peter; Franke, Thierry P; Randsdorp, Manon S; Koes, Bart W

2017-09-20

To review scientific literature studying the effectiveness of physical therapy and electrophysical modalities for carpal tunnel syndrome (CTS). The Cochrane Library, PubMed, Embase, CINAHL, and Physiotherapy Evidence Database. Two reviewers independently applied the inclusion criteria to select potential eligible studies. Two reviewers independently extracted the data and assessed the methodologic quality using the Cochrane Risk of Bias Tool. A best-evidence synthesis was performed to summarize the results of the included studies (2 reviews and 22 randomized controlled trials [RCTs]). For physical therapy, moderate evidence was found for myofascial massage therapy versus ischemic compression on latent, or active, trigger points or low-level laser therapy in the short term. For several electrophysical modalities, moderate evidence was found in the short term (ultrasound vs placebo, ultrasound as single intervention vs other nonsurgical interventions, ultrasound vs corticosteroid injection plus a neutral wrist splint, local microwave hyperthermia vs placebo, iontophoresis vs phonophoresis, pulsed radiofrequency added to wrist splint, continuous vs pulsed vs placebo shortwave diathermy, and interferential current vs transcutaneous electrical nerve stimulation vs a night-only wrist splint). In the midterm, moderate evidence was found in favor of radial extracorporeal shockwave therapy (ESWT) added to a neutral wrist splint, in favor of ESWT versus ultrasound, or cryo-ultrasound, and in favor of ultrasound versus placebo. For all other interventions studied, only limited, conflicting, or no evidence was found. No RCTs investigating the long-term effects of physical therapy and electrophysical modalities were found. Because of heterogeneity in the treatment parameters used in the included RCTs, optimal treatment parameters could not be identified. Moderate evidence was found for several physical therapy and electrophysical modalities for CTS in the short term and midterm. Future studies should concentrate on long-term effects and which treatment parameters of physical therapy and electrophysical modalities are most effective for CTS. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Modeling weakly-ionized plasmas in magnetic field: A new computationally-efficient approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parent, Bernard, E-mail: parent@pusan.ac.kr; Macheret, Sergey O.; Shneider, Mikhail N.

2015-11-01

Despite its success at simulating accurately both non-neutral and quasi-neutral weakly-ionized plasmas, the drift-diffusion model has been observed to be a particularly stiff set of equations. Recently, it was demonstrated that the stiffness of the system could be relieved by rewriting the equations such that the potential is obtained from Ohm's law rather than Gauss's law while adding some source terms to the ion transport equation to ensure that Gauss's law is satisfied in non-neutral regions. Although the latter was applicable to multicomponent and multidimensional plasmas, it could not be used for plasmas in which the magnetic field was significant.more » This paper hence proposes a new computationally-efficient set of electron and ion transport equations that can be used not only for a plasma with multiple types of positive and negative ions, but also for a plasma in magnetic field. Because the proposed set of equations is obtained from the same physical model as the conventional drift-diffusion equations without introducing new assumptions or simplifications, it results in the same exact solution when the grid is refined sufficiently while being more computationally efficient: not only is the proposed approach considerably less stiff and hence requires fewer iterations to reach convergence but it yields a converged solution that exhibits a significantly higher resolution. The combined faster convergence and higher resolution is shown to result in a hundredfold increase in computational efficiency for some typical steady and unsteady plasma problems including non-neutral cathode and anode sheaths as well as quasi-neutral regions.« less

ECR Plasma Source for Heavy Ion Beam Charge Neutralization

NASA Astrophysics Data System (ADS)

Efthimion, P. C.; Gilson, E.; Grisham, L.; Davidson, R. C.; Yu, S.; Logan, B. G.

2002-11-01

Highly ionized plasmas are being considered as a medium for charge neutralizing heavy ion beams in order to focus beyond the space-charge limit. Calculations suggest that plasma at a density of 1 - 100 times the ion beam density and at a length ˜ 0.1-0.5 m would be suitable for achieving a high level of charge neutralization. An ECR source has been built at the Princeton Plasma Physics Laboratory (PPPL) to support a joint Neutralized Transport Experiment (NTX) at the Lawrence Berkeley National Laboratory (LBNL) to study ion beam neutralization with plasma. The ECR source operates at 13.6 MHz and with solenoid magnetic fields of 1-10 gauss. The goal is to operate the source at pressures ˜ 10-5 Torr at full ionization. The initial operation of the source has been at pressures of 10-4 - 10-1 Torr. Electron densities in the range of 10^8 - 10^11 cm-3 have been achieved. Low-pressure operation is important to reduce ion beam ionization. A cusp magnetic field has been installed to improve radial confinement and reduce the field strength on the beam axis. In addition, axial confinement is believed to be important to achieve lower-pressure operation. At moderate pressures (> 1 mTorr) the wave damping is collisional, and at low pressures (< 1 mTorr) there is a distinct electron cyclotron resonance. The source has recently been configured to operate with 2.45 GHz microwaves with similar results. At the present operating range the source can simulate the plasma produced by photo-ionization in the target chamber.

ECR plasma source for heavy ion beam charge neutralization

NASA Astrophysics Data System (ADS)

Efthimion, Philip C.; Gilson, Erik; Grisham, Larry; Kolchin, Pavel; Davidson, Ronald C.; Yu, Simon; Logan, B. Grant

2003-01-01

Highly ionized plasmas are being considered as a medium for charge neutralizing heavy ion beams in order to focus beyond the space-charge limit. Calculations suggest that plasma at a density of 1 100 times the ion beam density and at a length [similar]0.1 2 m would be suitable for achieving a high level of charge neutralization. An Electron Cyclotron Resonance (ECR) source has been built at the Princeton Plasma Physics Laboratory (PPPL) to support a joint Neutralized Transport Experiment (NTX) at the Lawrence Berkeley National Laboratory (LBNL) to study ion beam neutralization with plasma. The ECR source operates at 13.6 MHz and with solenoid magnetic fields of 1 10 gauss. The goal is to operate the source at pressures [similar]10[minus sign]6 Torr at full ionization. The initial operation of the source has been at pressures of 10[minus sign]4 10[minus sign]1 Torr. Electron densities in the range of 108 to 1011 cm[minus sign]3 have been achieved. Low-pressure operation is important to reduce ion beam ionization. A cusp magnetic field has been installed to improve radial confinement and reduce the field strength on the beam axis. In addition, axial confinement is believed to be important to achieve lower-pressure operation. To further improve breakdown at low pressure, a weak electron source will be placed near the end of the ECR source. This article also describes the wave damping mechanisms. At moderate pressures (> 1 mTorr), the wave damping is collisional, and at low pressures (< 1 mTorr) there is a distinct electron cyclotron resonance.

Effects of synchronous music on treadmill running among elite triathletes.

PubMed

Terry, Peter C; Karageorghis, Costas I; Saha, Alessandra Mecozzi; D'Auria, Shaun

2012-01-01

Music can provide ergogenic, psychological, and psychophysical benefits during physical activity, especially when movements are performed synchronously with music. The present study developed the train of research on synchronous music and extended it to elite athletes. Repeated-measures laboratory experiment. Elite triathletes (n=11) ran in time to self-selected motivational music, a neutral equivalent and a no-music control during submaximal and exhaustive treadmill running. Measured variables were time-to-exhaustion, mood responses, feeling states, RPE, blood lactate concentration, oxygen consumption and running economy. Time-to-exhaustion was 18.1% and 19.7% longer, respectively, when running in time to motivational and neutral music, compared to no music. Mood responses and feeling states were more positive with motivational music compared to either neutral music or no music. RPE was lowest for neutral music and highest for the no-music control. Blood lactate concentrations were lowest for motivational music. Oxygen consumption was lower with music by 1.0%-.7%. Both music conditions were associated with better running economy than the no-music control. Although neutral music did not produce the same level of psychological benefits as motivational music, it proved equally beneficial in terms of time-to-exhaustion and oxygen consumption. In functional terms, the motivational qualities of music may be less important than the prominence of its beat and the degree to which participants are able to synchronise their movements to its tempo. Music provided ergogenic, psychological and physiological benefits in a laboratory study and its judicious use during triathlon training should be considered. Copyright © 2011 Sports Medicine Australia. All rights reserved.

Finite size effects in the thermodynamics of a free neutral scalar field

NASA Astrophysics Data System (ADS)

Parvan, A. S.

2018-04-01

The exact analytical lattice results for the partition function of the free neutral scalar field in one spatial dimension in both the configuration and the momentum space were obtained in the framework of the path integral method. The symmetric square matrices of the bilinear forms on the vector space of fields in both configuration space and momentum space were found explicitly. The exact lattice results for the partition function were generalized to the three-dimensional spatial momentum space and the main thermodynamic quantities were derived both on the lattice and in the continuum limit. The thermodynamic properties and the finite volume corrections to the thermodynamic quantities of the free real scalar field were studied. We found that on the finite lattice the exact lattice results for the free massive neutral scalar field agree with the continuum limit only in the region of small values of temperature and volume. However, at these temperatures and volumes the continuum physical quantities for both massive and massless scalar field deviate essentially from their thermodynamic limit values and recover them only at high temperatures or/and large volumes in the thermodynamic limit.

Neutralization of space charge forces using ionized background gas

NASA Astrophysics Data System (ADS)

Steski, D. B.; Zarcone, M. J.; Smith, K. S.; Thieberger, P.

1996-03-01

The Tandem Van de Graaff at Brookhaven National Laboratory has delivered pulsed gold beam to the Alternating Gradient Synchrotron (AGS) and AGS Booster since 1992 for relativistic heavy ion physics. There is an ongoing effort to improve the quality and intensity of the negative ion beam delivered to the Tandem from the present Cs sputter sources. Because the beam energy is low (approximately 30 keV) and the current high, there are significant losses due to space charge forces. One of the ways being explored to overcome these losses is to neutralize the space charge forces with ionized background gas. On an ion source test bench, using three different gases (Ar, N2, and Xe), the percentage of current transported from the source to a downstream Faraday cup was increased from 10% to 40% by bleeding in gas. Bleeding in Xe resulted in the best transmission. The time dependence of the neutralization as a function of gas pressure was also observed. This system is presently being transferred to the Negative Ion Injector of the Tandem for use in upcoming heavy ion experiments.

Deutsch, Toffoli, and cnot Gates via Rydberg Blockade of Neutral Atoms

NASA Astrophysics Data System (ADS)

Shi, Xiao-Feng

2018-05-01

Universal quantum gates and quantum error correction (QEC) lie at the heart of quantum-information science. Large-scale quantum computing depends on a universal set of quantum gates, in which some gates may be easily carried out, while others are restricted to certain physical systems. There is a unique three-qubit quantum gate called the Deutsch gate [D (θ )], from which a circuit can be constructed so that any feasible quantum computing is attainable. We design an easily realizable D (θ ) by using the Rydberg blockade of neutral atoms, where θ can be tuned to any value in [0 ,π ] by adjusting the strengths of external control fields. Using similar protocols, we further show that both the Toffoli and controlled-not gates can be achieved with only three laser pulses. The Toffoli gate, being universal for classical reversible computing, is also useful for QEC, which plays an important role in quantum communication and fault-tolerant quantum computation. The possibility and speed of realizing these gates shed light on the study of quantum information with neutral atoms.

The effect of uncontrolled moment and short-term, repeated passive stretching on maximum ankle joint dorsiflexion angle.

PubMed

Gatt, Alfred; Chockalingam, Nachiappan

2012-06-01

Trials investigating ankle joint measurement normally apply a known moment. Maximum ankle angle is affected by foot posture and stretching characteristics of the calf muscles. To investigate whether consistent maximum ankle angles could be achieved without applying a constant moment to all subjects, and whether short, repetitive stretching of the calf muscle tendon unit would produce a difference in the maximum ankle angle. Passive dorsiflexion in 14 healthy participants was captured using an optoelectronic motion analysis system, with the foot placed in 3 postures. The maximum ankle angles for both the neutral and supinated positions did not differ significantly. In general, the majority of subjects (92.8%) showed no increase in the maximum ankle dorsiflexion angle following repetitive brief passive stretching. Only one subject exhibited a significant increase in maximum ankle angle at the neutral position. Since the range of motion of the ankle joint is clearly determined by other physical factors, the maximum ankle dorsiflexion angle can be assessed at both neutral and supinated positions without moment being controlled. Copyright © 2011 Elsevier Ltd. All rights reserved.

Planned Experiments on the Princeton Advanced Test Stand

NASA Astrophysics Data System (ADS)

Stepanov, A.; Gilson, E. P.; Grisham, L.; Kaganovich, I.; Davidson, R. C.

2010-11-01

The Princeton Advanced Test Stand (PATS) device is an experimental facility based on the STS-100 high voltage test stand transferred from LBNL. It consists of a multicusp RF ion source, a pulsed extraction system capable of forming high-perveance 100keV ion beams, and a large six-foot-long vacuum with convenient access for beam diagnostics. This results in a flexible system for studying high perveance ion beams relevant to NDCX-I/II, including experiments on beam neutralization by ferroelectric plasma sources (FEPS) being developed at PPPL. Research on PATS will concern the basic physics of beam-plasma interactions, such as the effects of volume neutralization on beam emittance, as well as optimizing technology of the FEPS. PATS combines the advantage of an ion beam source and a large-volume plasma source in a chamber with ample access for diagnostics, resulting in a robust setup for investigating and improving relevant aspects of neutralized drift. There are also plans for running the ion source with strongly electro-negative gases such as chlorine, making it possible to extract positive or negative ion beams.

Short intense ion pulses for materials and warm dense matter research

DOE PAGES

Seidl, Peter A.; Persaud, Arun; Waldron, William L.; ...

2015-08-14

We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r<1 mm within 2 ns FWHM and approximately 10 10 ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li + ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientificmore » topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Finally, we describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminum perovskite using the fully integrated accelerator and neutralized drift compression components.« less

Development progresses of radio frequency ion source for neutral beam injector in fusion devices.

PubMed

Chang, D H; Jeong, S H; Kim, T S; Park, M; Lee, K W; In, S R

2014-02-01

A large-area RF (radio frequency)-driven ion source is being developed in Germany for the heating and current drive of an ITER device. Negative hydrogen ion sources are the major components of neutral beam injection systems in future large-scale fusion experiments such as ITER and DEMO. RF ion sources for the production of positive hydrogen (deuterium) ions have been successfully developed for the neutral beam heating systems at IPP (Max-Planck-Institute for Plasma Physics) in Germany. The first long-pulse ion source has been developed successfully with a magnetic bucket plasma generator including a filament heating structure for the first NBI system of the KSTAR tokamak. There is a development plan for an RF ion source at KAERI to extract the positive ions, which can be applied for the KSTAR NBI system and to extract the negative ions for future fusion devices such as the Fusion Neutron Source and Korea-DEMO. The characteristics of RF-driven plasmas and the uniformity of the plasma parameters in the test-RF ion source were investigated initially using an electrostatic probe.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Howard, T. A., E-mail: howard@boulder.swri.edu

Measurements of Hα emission within an eruptive solar prominence are presented, using white light polarization properties as a proxy for the presence of Hα in the STEREO COR1 and COR2 coronagraphs. The transition from Hα emission to Thomson scattering radiance serves as an indicator of the ionization of the prominence, and I discuss the physical implications regarding the behavior of the neutrals and ions, and also for the measurement of coronal mass ejection properties using the Thomson scattering assumption. I find that the prominence has a high concentration of neutrals at around two solar radii that gradually exhibit ionization characteristics atmore » it moves away from the Sun. The prominence reaches complete ionization, or at least a state where the Thomson-scattered brightness dominates, by the time it reaches around seven solar radii. This is consistent with predictions inferred from direct Hα measurements made from earlier studies in the 1980s and with the predicted ionization rate of neutral hydrogen near solar maximum. These results pave the way for an accompanying paper that reports on measurements of the prominence at large distances from the Sun using the assumptions verified here.« less

Laser fluence dependence on emission dynamics of ultrafast laser induced copper plasma

DOE PAGES

Anoop, K. K.; Harilal, S. S.; Philip, Reji; ...

2016-11-14

The characteristic emission features of a laser-produced plasma strongly depend strongly on the laser fluence. We investigated the spatial and temporal dynamics of neutrals and ions in femtosecond laser (800 nm, ≈ 40 fs, Ti:Sapphire) induced copper plasma in vacuum using both optical emission spectroscopy (OES) and spectrally resolved two-dimensional (2D) imaging methods over a wide fluence range of 0.5 J/cm 2-77.5 J/cm 2. 2D fast gated monochromatic images showed distinct plume splitting between the neutral and ions especially at moderate to higher fluence ranges. OES studies at low to moderate laser fluence regime confirm intense neutral line emission overmore » the ion emission whereas this trend changes at higher laser fluence with dominance of the latter. This evidences a clear change in the physical processes involved in femtosecond laser matter interaction at high input laser intensity. The obtained ion dynamics resulting from the OES, and spectrally resolved 2D imaging are compared with charged particle measurement employing Faraday cup and Langmuir probe and results showed good correlation.« less

In-silico studies of neutral drift for functional protein interaction networks

NASA Astrophysics Data System (ADS)

Ali, Md Zulfikar; Wingreen, Ned S.; Mukhopadhyay, Ranjan

We have developed a minimal physically-motivated model of protein-protein interaction networks. Our system consists of two classes of enzymes, activators (e.g. kinases) and deactivators (e.g. phosphatases), and the enzyme-mediated activation/deactivation rates are determined by sequence-dependent binding strengths between enzymes and their targets. The network is evolved by introducing random point mutations in the binding sequences where we assume that each new mutation is either fixed or entirely lost. We apply this model to studies of neutral drift in networks that yield oscillatory dynamics, where we start, for example, with a relatively simple network and allow it to evolve by adding nodes and connections while requiring that dynamics be conserved. Our studies demonstrate both the importance of employing a sequence-based evolutionary scheme and the relative rapidity (in evolutionary time) for the redistribution of function over new nodes via neutral drift. Surprisingly, in addition to this redistribution time we discovered another much slower timescale for network evolution, reflecting hidden order in sequence space that we interpret in terms of sparsely connected domains.

Charged-to-neutral correlation at forward rapidity in Au+Au collisions at s NN = 200 GeV

DOE PAGES

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...

2015-03-20

Event-by-event fluctuations of the ratio of inclusive charged to photon multiplicities at forward rapidity in Au+Au collision at √s NN=200 GeV have been studied. Dominant contribution to such fluctuations is expected to come from correlated production of charged and neutral pions. We search for evidences of dynamical fluctuations of different physical origins. Observables constructed out of moments of multiplicities are used as measures of fluctuations. Mixed events and model calculations are used as baselines. Results are compared to the dynamical net-charge fluctuations measured in the same acceptance. A non-zero statistically significant signal of dynamical fluctuations is observed in excess tomore » the model prediction when charged particles and photons are measured in the same acceptance. Thus, we find that, unlike dynamical net-charge fluctuation, charge-neutral fluctuation is not dominated by correlation due to particle decay. Results are compared to the expectations based on the generic production mechanism of pions due to isospin symmetry, for which no significant (< 1%) deviation is observed.« less

Modeling the cometary environment using a fluid approach

NASA Astrophysics Data System (ADS)

Shou, Yinsi

Comets are believed to have preserved the building material of the early solar system and to hold clues to the origin of life on Earth. Abundant remote observations of comets by telescopes and the in-situ measurements by a handful of space missions reveal that the cometary environments are complicated by various physical and chemical processes among the neutral gases and dust grains released from comets, cometary ions, and the solar wind in the interplanetary space. Therefore, physics-based numerical models are in demand to interpret the observational data and to deepen our understanding of the cometary environment. In this thesis, three models using a fluid approach, which include important physical and chemical processes underlying the cometary environment, have been developed to study the plasma, neutral gas, and the dust grains, respectively. Although models based on the fluid approach have limitations in capturing all of the correct physics for certain applications, especially for very low gas density environment, they are computationally much more efficient than alternatives. In the simulations of comet 67P/Churyumov-Gerasimenko at various heliocentric distances with a wide range of production rates, our multi-fluid cometary neutral gas model and multi-fluid cometary dust model have achieved comparable results to the Direct Simulation Monte Carlo (DSMC) model, which is based on a kinetic approach that is valid in all collisional regimes. Therefore, our model is a powerful alternative to the particle-based model, especially for some computationally intensive simulations. Capable of accounting for the varying heating efficiency under various physical conditions in a self-consistent way, the multi-fluid cometary neutral gas model is a good tool to study the dynamics of the cometary coma with different production rates and heliocentric distances. The modeled H2O expansion speeds reproduce the general trend and the speed's nonlinear dependencies of production rate and heliocentric distance, which are found in remote observations. In the multi-fluid dust model, we use a newly developed numerical mesh to resolve the real shaped nucleus in the center and to facilitate prescription of the outer boundary conditions that accommodate the rotating frame. The model studies the effects of the rotating nucleus and the cometary activity in time-dependent simulations for the first time. The result also suggests that the rotation of the nucleus explains why there is no clear dust speed dependence on size in some of the dust observations. We developed a new multi-species comet MHD model to simulate the plasma environment of comet C/2006 P1 (McNaught) over a wide range of heliocentric distances from 0.17 AU to 1.75 AU, with the constraints provided by remote and in situ observations. Typical subsolar standoff distances of bow shock and contact surface are modeled and presented to characterize the solar wind interaction of the comet at various heliocentric distances. In addition, the model is also the first one to be used to study the composition and dynamics in the distant cometary tail. The results agree well with the measured water group ion abundances from the Ulysses/SWICS 1.7 AU down-tail from the comet and the velocity and temperature measured by Ulysses/SWOOPS.

A Web 2.0 Interface to Ion Stopping Power and Other Physics Routines for High Energy Density Physics Applications

NASA Astrophysics Data System (ADS)

Stoltz, Peter; Veitzer, Seth

2008-04-01

We present a new Web 2.0-based interface to physics routines for High Energy Density Physics applications. These routines include models for ion stopping power, sputtering, secondary electron yields and energies, impact ionization cross sections, and atomic radiated power. The Web 2.0 interface allows users to easily explore the results of the models before using the routines within other codes or to analyze experimental results. We discuss how we used various Web 2.0 tools, including the Python 2.5, Django, and the Yahoo User Interface library. Finally, we demonstrate the interface by showing as an example the stopping power algorithms researchers are currently using within the Hydra code to analyze warm, dense matter experiments underway at the Neutralized Drift Compression Experiment facility at Lawrence Berkeley National Laboratory.

The Solar-Terrestrial Environment

NASA Astrophysics Data System (ADS)

Hargreaves, John Keith

1995-05-01

The book begins with three introductory chapters that provide some basic physics and explain the principles of physical investigation. The principal material contained in the main part of the book covers the neutral and ionized upper atmosphere, the magnetosphere, and structures, dynamics, disturbances, and irregularities. The concluding chapter deals with technological applications. The account is introductory, at a level suitable for readers with a basic background in engineering or physics. The intent is to present basic concepts, and for that reason, the mathematical treatment is not complex. SI units are given throughout, with helpful notes on cgs units where these are likely to be encountered in the research literature. This book is suitable for advanced undergraduate and graduate students who are taking introductory courses on upper atmospheric, ionospheric, or magnetospheric physics. This is a successor to The Upper Atmosphere and Solar-Terrestrial Relations, published in 1979.

Hot electrons and radial transport in Saturn's inner magetosphere: Modeling the effects on ion chemistry

NASA Astrophysics Data System (ADS)

Fleshman, Bobby L.

The E-ring of Saturn, located just beyond the main rings at four Saturn radii, was known to be made mostly of water and its by-products before the Cassini spacecraft arrived at Saturn in 2005. Since then, Cassini has observed water geysers on the tiny moon of Enceladus ejecting ≈ 100 kg of water per second into orbit around Saturn, which most agree is the chief contributor to neutrals in the E-ring. Following several key reactions, many of these neutrals go on to populate large, tenuous structures, known as neutral clouds, extending 10s of Saturn radii. The other side of the story are the ions, which are largely created by the ionization of same neutrals sourced from Enceladus. A key distinction between the neutrals and ions is that ions are carried along by Saturn's magnetic field, and revolve around Saturn at the rotation rate of the planet, while neutrals generally have much slower Keplerian speeds. It is the study of the chemical interaction of these separate, but related populations that is the subject of this thesis. We have developed a series of models to study how the coupling of these systems affect details of the other, such as composition. The first step (Chapter 2) was the development of a water-group physical chemistry model, which includes suprathermal electrons and the effect of radial ion transport. With this "one-box" model, we are able to reproduce observed water and hydrogen ion densities in Enceladus's orbit, but only when the hot electron density is ≈ 0.5% of the total plasma density. Radial transport is found to be slow, requiring 26 days to remove ions from the orbit of Enceladus. Moving toward the development of a radial model of ion chemistry, in Chapter 4 we present a model of Saturn's neutral clouds, which are made of material outgassing from Enceladus. The effects of dissociation and charge exchange are considered, where the details of the latter prove to be of great consequence on neutral cloud morphology. The oxygen cloud is found to the most extended, followed by H2O, and finally OH. The above efforts are combined in Chapter 5, where a neutral cloud model is used to construct a radial model of ion chemistry. It is shown that neutral H2O requires more spreading than yet modeled in order to recover observed water and hydrogen ion abundances near Enceladus. The relative abundance of water-group ion species presented will be useful for analyses of CAPS-IMS data, while loss rates derived from the model can be used to improve neutral cloud models. The case is made that ion chemistry models and neutral cloud models must be developed alongside one another in order to improve understanding of these interrelated populations at Saturn.

Charmless and Penguin Decays at CDF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dorigo, Mirco; Collaboration, for the CDF

2010-12-01

Penguin transitions play a key role in the search of New Physics hints in the heavy flavor sector. During the last decade CDF has been exploring this opportunity with a rich study of two-body charmless decays of neutral B mesons into charged final-state particles. After briefly introducing the aspects of this physics peculiar to the hadron collision environment, I report on two interesting results: the first polarization measurement of the B{sub s}{sup 0} {yields} {phi}{phi} decay and the update of the B{sub (s)}{sup 0} {yields} h{sup +}h{prime}{sup -} decays analysis.

Calculations of combustion response profiles and oscillations

NASA Technical Reports Server (NTRS)

Priem, Richard J.; Breisacher, Kevin J.

1993-01-01

The theory and procedures for determining the characteristics of pressure oscillations in rocket engines with prescribed burning rate oscillations are presented. Pressure and velocity oscillations calculated using this procedure are presented for the Space Shuttle Main Engine (SSME) to show the influence of baffles and absorbers on the burning rate oscillations required to achieve neutral stability. Results of calculations to determine local combustion responses using detailed physical models for injection, atomization, and vaporization with gas phase oscillations in baffled and unbaffled SSME combustors are presented. The contributions of the various physical phenomena occurring in a combustor to oscillations in combustion response were determined.

V. S. Lebedev and I. L. Beigman, Physics of Highly Excited Atoms and Ions

NASA Astrophysics Data System (ADS)

Mewe, R.

1999-07-01

This book contains a comprehensive description of the basic principles of the theoretical spectroscopy and experimental spectroscopic diagnostics of Rydberg atoms and ions, i.e., atoms in highly excited states with a very large principal quantum number (n≫1). Rydberg atoms are characterized by a number of peculiar physical properties as compared to atoms in the ground or a low excited state. They have a very small ionization potential (∝1/n2), the highly excited electron has a small orbital velocity (∝1/n), the radius (∝n2) is very large, the excited electron has a long orbital period (∝n3), and the radiation lifetime is very long (∝n3-5). At the same time the R. atom is very sensitive to perturbations from external fields in collisions with charged and neutral targets. In recent years, R. atoms have been observed in laboratory and cosmic conditions for n up to ˜1000, which means that the size amounts to about 0.1 mm, ˜106 times that of an atom in the ground state. The scope of this monograph is to familiarize the reader with today's approaches and methods for describing isolated R. atoms and ions, radiative transitions between highly excited states, and photoionization and photorecombination processes. The authors present a number of efficient methods for describing the structure and properties of R. atoms and calculating processes of collisions with neutral and charged particles as well as spectral-line broadening and shift of Rydberg atomic series in gases, cool and hot plasmas in laboratories and in astrophysical sources. Particular attention is paid to a comparison of theoretical results with available experimental data. The book contains 9 chapters. Chapter 1 gives an introduction to the basic properties of R. atoms (ions), Chapter 2 is devoted to an account of general methods describing an isolated Rydberg atom. Chapter 3 is focussed on the recent achievements in calculations of form factors and dipole matrix elements of different types of bound-bound and bound-free radiative transitions. Chapter 4 concentrates on the formulation of basic theoretical methods and physical approaches to collisions involving R. atoms. Chapters 5 to 8 contain a systematic description of major directions and modern techniques in the collision theory of R. atoms and ions with atoms, molecules, electrons, and ions. Finally, Chapter 9 deals with the spectral-line broadening and shift of R. atomic series induced by collisions with neutral and charged particles. A subject index of four pages and 250 references are given. This monograph will be a basic tool and reference for all scientists working in the fields of plasma physics, spectroscopy, physics of electronic and atomic collisions, as well as astrophysics, radio astronomy, and space physics.

Interstellar PAH in the Laboratory and in Space. What have we Learned from the New Generation of Laboratory and Observational Studies?

NASA Technical Reports Server (NTRS)

Salama, Farid

2005-01-01

Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. PAHs are the best-known candidates to account for the IR emission bands (UIR bands) and PAH spectral features are now being used as new probes of the ISM. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory astrophysics is to reproduce (in a realistic way) the physical conditions that exist in the emission and/or absorption interstellar zones. An extensive laboratory program has been developed at NASA Ames to assess the physical and chemical properties of PAHs in such environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. In particular, laboratory experiments provide measurements of the spectral characteristics of interstellar PAH analogs from the ultraviolet and visible range to the infrared range for comparison with astronomical data. This paper will focus on the recent progress made in the laboratory to measure the direct absorption spectra of neutral and ionized PAHs in the gas phase in the near-UV and visible range in astrophysically relevant environments. These measurements provide data on PAHs and nanometer-sized particles that can now be directly compared to astronomical observations. The harsh physical conditions of the IS medium - characterized by a low temperature, an absence of collisions and strong VUV radiation fields - are simulated in the laboratory by associating a molecular beam with an ionizing discharge to generate a cold plasma expansion. PAH ions are formed from the neutral precursors in an isolated environment at low temperature (of the order of 100 K). The spectra of neutral and ionized PAHs are measured using the high sensitivity methods of cavity ring down spectroscopy (CRDS). These experiments provide unique information on the spectra of free, cold large carbon molecules and ions in the gas phase. Intrinsic band profiles and band positions of cold gas-phase PAHs can now be measured with high-sensitivity spectroscopy and directly compared to the astronomical data. The electronic bands measured for ionized PAH are found to be intrinsically broad (about 20 cm(sup -1)) while the bands associated with the neutral precursors are narrower (of the order of 2 - 10 cm(sup -1)). The laboratory data are discussed and compared with recent astronomical spectra of large and narrow DIBs and with the spectra of circumstellar environments of selected carbon stars and the implications for the interstellar PAH population are derived. Preliminary results also show that carbon nanoparticles are formed during the short residence time of the precursors in the plasma.

Understanding flavour at the LHC

ScienceCinema

Nir, Yosef

2018-05-22

Huge progress in flavour physics has been achieved by the two B-factories and the Tevatron experiments. This progress has, however, deepened the new physics flavour puzzle: If there is new physics at the TeV scale, why aren't flavour changing neutral current processes enhanced by orders of magnitude compared to the standard model predictions? The forthcoming ATLAS and CMS experiments can potentially solve this puzzle. Perhaps even more surprisingly, these experiments can potentially lead to progress in understanding the standard model flavour puzzle: Why is there smallness and hierarchy in the flavour parameters? Thus, a rich and informative flavour program is awaiting us not only in the flavour-dedicated LHCb experiment, but also in the high-pT ATLAS and CMS experiments.

Inter-rater Reliability of Real-Time Ultrasound to Measure Acromiohumeral Distance.

PubMed

Mackenzie, Tanya Anne; Bdaiwi, Alya H; Herrington, Lee; Cools, Ann

2016-07-01

Real-time ultrasound (RTUS) has been suggested as a reliable measure of acromiohumeral distance. However, to date, no vigorous assessment and reporting of inter-rater reliability of this method has been performed with the shoulder in a neutral position or with active and passive arm abduction. To assess intrasession inter-rater reliability of using RTUS to measure acromiohumeral distance with the shoulder in a neutral position and with 60° active and passive abduction. Inter-rater intrasession reliability of repeated measures. Human performance laboratory. Twenty persons (12 male and 8 female) with an average age of 29.86 years (standard deviation, 7.8). In an inter-rater, intrasession study, RTUS was used to measure the acromiohumeral distance with the shoulder in a neutral position and with 60° of both active and passive abduction. Acromiohumeral distance. Intraclass correlation coefficient (ICC)2.1 scores ranged between 0.65-0.88 (standard error of the mean = 0.81-1.2 mm and minimal detectable differences with 95% confidence = 2.2-2.3 mm) for inter-rater intrasession reliability. RTUS was found to have fair to good inter-rater reliability as a tool to measure acromiohumeral distance with the shoulder in a neutral position and with 60° of both active and passive arm abduction. Copyright © 2016 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Ion composition variety and variability around perihelion

NASA Astrophysics Data System (ADS)

Beth, Arnaud; Altwegg, Kathrin; Behar, Étienne; Broiles, Tom; Burch, Jim; Carr, Christopher; Eriksson, Anders; Galand, Marina; Goetz, Charlotte; Henri, Pierre; Heritier, Kévin; Nilsson, Hans; Odelstad, Elias; Richter, Ingo; Rubin, Martin; Vallieres, Xavier

2017-04-01

For two years, the Double Focusing Mass Spectrometer (DFMS), one of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) onboard Rosetta probed the neutral gas and the plasma composition of the comet 67P/Churyumov-Gerasimenko's coma (67P). Major ion species detected include water ions (e.g, H2O+, H3O+, HO+) observed throughout the escorting phase. The analysis of DFMS data revealed a large zoo of ion species near perihelion (summer 2015). In particular, protonated versions of high proton affinity neutrals (e.g., NH4+) were detected, but also hydrocarbon and organic ion species. Near perihelion, ion composition was also highly variable and showed interesting variations in the complexity of the observed ion species. We will first present an overview of the rich variety of ion species observed during perihelion. This study will be supported by ionospheric modeling of ion composition below the ion exobase. We will then show an intercomparison between DFMS data and Rosetta Plasma Consortium (RPC) plasma and particle data to interpret the DFMS ion composition variability. Our primary goal is to highlight any correlation between observations from these different instruments (i.e. ion composition, ion and electron number density, energy distribution, magnetic field) and to find relevant signatures of physical processes which can affect the chemistry and dynamics (e.g., acceleration and deflection) of the involved neutral and ion species.

Two-dimensional Dirac fermions in thin films of C d3A s2

NASA Astrophysics Data System (ADS)

Galletti, Luca; Schumann, Timo; Shoron, Omor F.; Goyal, Manik; Kealhofer, David A.; Kim, Honggyu; Stemmer, Susanne

2018-03-01

Two-dimensional states in confined thin films of the three-dimensional Dirac semimetal C d3A s2 are probed by transport and capacitance measurements under applied magnetic and electric fields. The results establish the two-dimensional Dirac electronic spectrum of these states. We observe signatures of p -type conduction in the two-dimensional states as the Fermi level is tuned across their charge neutrality point and the presence of a zero-energy Landau level, all of which indicate topologically nontrivial states. The resistance at the charge neutrality point is approximately h /e2 and increases rapidly under the application of a magnetic field. The results open many possibilities for gate-tunable topological devices and for the exploration of novel physics in the zero-energy Landau level.

Semi-analytical study of the tokamak pedestal density profile in a single-null diverted plasma with puffing-recycling gas sources

NASA Astrophysics Data System (ADS)

Shi, Bingren

2010-10-01

The tokamak pedestal density structure is generally studied using a diffusion-dominant model. Recent investigations (Stacey and Groebner 2009 Phys. Plasmas 16 102504) from first principle based physics have shown a plausible existence of large inward convection in the pedestal region. The diffusion-convection equation with rapidly varying convection and diffusion coefficients in the near edge region and model puffing-recycling neutral particles is studied in this paper. A peculiar property of its solution for the existence of the large convection case is that the pedestal width of the density profile, qualitatively different from the diffusion-dominant case, depends mainly on the width of the inward convection and only weakly on the neutral penetration length and its injection position.

Temporal parallelization of edge plasma simulations using the parareal algorithm and the SOLPS code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samaddar, Debasmita; Coster, D. P.; Bonnin, X.

We show that numerical modelling of edge plasma physics may be successfully parallelized in time. The parareal algorithm has been employed for this purpose and the SOLPS code package coupling the B2.5 finite-volume fluid plasma solver with the kinetic Monte-Carlo neutral code Eirene has been used as a test bed. The complex dynamics of the plasma and neutrals in the scrape-off layer (SOL) region makes this a unique application. It is demonstrated that a significant computational gain (more than an order of magnitude) may be obtained with this technique. The use of the IPS framework for event-based parareal implementation optimizesmore » resource utilization and has been shown to significantly contribute to the computational gain.« less

Temporal parallelization of edge plasma simulations using the parareal algorithm and the SOLPS code

DOE PAGES

Samaddar, Debasmita; Coster, D. P.; Bonnin, X.; ...

2017-07-31

We show that numerical modelling of edge plasma physics may be successfully parallelized in time. The parareal algorithm has been employed for this purpose and the SOLPS code package coupling the B2.5 finite-volume fluid plasma solver with the kinetic Monte-Carlo neutral code Eirene has been used as a test bed. The complex dynamics of the plasma and neutrals in the scrape-off layer (SOL) region makes this a unique application. It is demonstrated that a significant computational gain (more than an order of magnitude) may be obtained with this technique. The use of the IPS framework for event-based parareal implementation optimizesmore » resource utilization and has been shown to significantly contribute to the computational gain.« less

THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS: Neutrino Oscillation Induced by Chiral Phase Transition

NASA Astrophysics Data System (ADS)

Mu, Cheng-Fu; Sun, Gao-Feng; Zhuang, Peng-Fei

2009-03-01

Electric charge neutrality provides a relationship between chiral dynamics and neutrino propagation in compact stars. Due to the sudden drop of the electron density at thefirst-order chiral phase transition, the oscillation for low energy neutrinos is significant and can be regarded as a signature of chiral symmetry restoration in the core of compact stars.

Introduction: Particles and fields

NASA Astrophysics Data System (ADS)

Moore, Thomas; Spann, James

2017-02-01

A Conference on Measurement Techniques for Solar and Space Physics was held on 20-24 April 2015 in Boulder, Colorado, at the National Center for Atmospheric Research Center Green Campus. The present volume collects together the papers from this conference in the categories of particles and fields. This also includes neutral gas techniques as well as low-energy ionospheric plasmas and their interactions with spacecrafts.

Introduction: Particles and Fields

NASA Technical Reports Server (NTRS)

Moore, Thomas E.; Spann, James F.

2017-01-01

A Conference on Measurement Techniques for Solar and Space Physics was held on 20-24 April 2015 in Boulder, Colorado, at the National Center for Atmospheric Research Center Green Campus. The present volume collects together the papers from this conference in the categories of particles and fields. This also includes neutral gas techniques as well as low-energy ionospheric plasmas and their interactions with spacecrafts.

USSR Report, Physics and Mathematics

DTIC Science & Technology

1985-08-20

TEKHNICHESKIY FIZIKI, No 6(148), Nov-Dec 84) 80 Thermodynamic Potential of Quark -Antiquark Plasma in Constant Chromomagnetic Field CSh. S. Agayev... QUARK -ANTIQUARK PLASMA IN CONSTANT CHROMOMAGNETIC FIELD Tomsk IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY: FIZIKA in Russian Vol 28, No 1, Jan 85...Automation Institute; Moscow State University imeni M. V. Lomonosov [Abstract] Light-neutral quark -antiquark plasma in a constant optical magnetic

A Tie for Third Place: Teens Need Physical Spaces as well as Virtual Places

ERIC Educational Resources Information Center

Heeger, Paula Brehm

2006-01-01

"Third places" or public and informal gathering places have declined over the years. Third places, which are "neutral ground" where people gather to discuss, interact, and enjoy the company of those they know, are important for the health of communities. It's a known fact that teens have a strong need to socialize, and their third-space options…

From Nominal to Quantitative Codification of Content-Neutral Variables in Graphics Research: The Beginnings of a Manifest Content Model.

ERIC Educational Resources Information Center

Crow, Wendell C.

This paper suggests ways in which manifest, physical attributes of graphic elements can be described and measured. It also proposes a preliminary conceptual model that accounts for the readily apparent, measurable variables in a visual message. The graphic elements that are described include format, typeface, and photographs/artwork. The…

Initial Study of Neutral Post-Instruction Responses on the Maryland Physics Expectation Survey

ERIC Educational Resources Information Center

Saltzman, J.; Price, M. F.; Rogers, M. B.

2016-01-01

Epistemological studies generally focus on how students think about their construction of knowledge compared to how experts think about the same ideas. Instruments such as the MPEX and CLASS use a Likert scale to gauge whether students agree or disagree with how experts think about the same ideas. During analysis, five point scale responses are…

Atmospheric stability and complex terrain: comparing measurements and CFD

NASA Astrophysics Data System (ADS)

Koblitz, T.; Bechmann, A.; Berg, J.; Sogachev, A.; Sørensen, N.; Réthoré, P.-E.

2014-12-01

For wind resource assessment, the wind industry is increasingly relying on Computational Fluid Dynamics models that focus on modeling the airflow in a neutrally stratified surface layer. So far, physical processes that are specific to the atmospheric boundary layer, for example the Coriolis force, buoyancy forces and heat transport, are mostly ignored in state-of-the-art flow solvers. In order to decrease the uncertainty of wind resource assessment, the effect of thermal stratification on the atmospheric boundary layer should be included in such models. The present work focuses on non-neutral atmospheric flow over complex terrain including physical processes like stability and Coriolis force. We examine the influence of these effects on the whole atmospheric boundary layer using the DTU Wind Energy flow solver EllipSys3D. To validate the flow solver, measurements from Benakanahalli hill, a field experiment that took place in India in early 2010, are used. The experiment was specifically designed to address the combined effects of stability and Coriolis force over complex terrain, and provides a dataset to validate flow solvers. Including those effects into EllipSys3D significantly improves the predicted flow field when compared against the measurements.

Charge separation and transport of the n=2 instability in C-2 FRC plasmas

NASA Astrophysics Data System (ADS)

Deng, Bihe; Sun, Xuan; Tuszewski, Michel

2012-10-01

Charge separation is critical in the positive feedback loop for gravitational type instabilities to grow [1], such as in the case of the n=2 mode in the C-2 field reversed configuration (FRC) experiment [2]. A fast time response Langmuir probe with minimum perturbation to the plasma is inserted into the edge of the C-2 plasma to measure the plasma floating potential. With the combined plasma wobble motion and spin motion, 2-D scans of the plasma floating potential are obtained, and evidence of charge separation associated with the n=2 instability is observed. The transport due to charge separation is estimated. Charge neutralization can provide an alternative method to stabilize the n=2 mode. An experiment is proposed to test this method with two probes inserted into the plasma from two azimuthally separated ports and an external shorting circuit, to constantly neutralize the charge separation, thus suppress the growth of the n=2 mode. [4pt] [1] R.J. Goldston and P.H. Rutherford, Introduction to Plasma Physics (Institute of Physics Publishing, Bristol, 2000).[0pt] [2]. M.W. Binderbauer et al, Phys. Rev. Lett. 105, 045003 (2010).

When abuse primes addiction - automatic activation of alcohol concepts by child maltreatment related cues in emotionally abused alcoholics.

PubMed

Potthast, Nadine; Neuner, Frank; Catani, Claudia

2015-09-01

Recent research indicates that there is a link between emotional maltreatment and alcohol dependence (AD), but the underlying mechanisms still need to be clarified. There is reason to assume that maltreatment related cues automatically activate an associative memory network comprising cues eliciting craving as well as alcohol-related responses. The current study aimed to examine this network in AD patients who experienced emotional abuse using a priming paradigm. A specific priming effect in emotionally abused AD subjects was hypothesized for maltreatment related words that preceded alcohol related words. 49 AD subjects (n=14 with emotional abuse vs. n=35 without emotional abuse) and 34 control subjects performed a priming task with maltreatment related and neutral prime words combined with alcohol related and neutral target words. Maltreatment related words consisted of socially and physically threatening words. As hypothesized, a specific priming effect for socially threatening and physically threatening cues was found only in AD subjects with emotional abuse. The present data are the first to provide evidence that child maltreatment related cues automatically activate an associative memory network in alcoholics with emotional abuse experiences. Copyright © 2015 Elsevier Ltd. All rights reserved.

Facilitating Effects of Emotion on the Perception of Biological Motion: Evidence for a Happiness Superiority Effect.

PubMed

Lee, Hannah; Kim, Jejoong

2017-06-01

It has been reported that visual perception can be influenced not only by the physical features of a stimulus but also by the emotional valence of the stimulus, even without explicit emotion recognition. Some previous studies reported an anger superiority effect while others found a happiness superiority effect during visual perception. It thus remains unclear as to which emotion is more influential. In the present study, we conducted two experiments using biological motion (BM) stimuli to examine whether emotional valence of the stimuli would affect BM perception; and if so, whether a specific type of emotion is associated with a superiority effect. Point-light walkers with three emotion types (anger, happiness, and neutral) were used, and the threshold to detect BM within noise was measured in Experiment 1. Participants showed higher performance in detecting happy walkers compared with the angry and neutral walkers. Follow-up motion velocity analysis revealed that physical difference among the stimuli was not the main factor causing the effect. The results of the emotion recognition task in Experiment 2 also showed a happiness superiority effect, as in Experiment 1. These results show that emotional valence (happiness) of the stimuli can facilitate the processing of BM.

A Particle-In-Cell Gun Code for Surface-Converter H- Ion Source Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chacon-Golcher, Edwin; Bowers, Kevin J.

2007-08-10

We present the current status of a particle-in-cell with Monte Carlo collisions (PIC-MCC) gun code under development at Los Alamos for the study of surface-converter H- ion sources. The program preserves a first-principles approach to a significant extent and simulates the production processes without ad hoc models within the plasma region. Some of its features include: solution of arbitrary electrostatic and magnetostatic fields in an axisymmetric (r,z) geometry to describe the self-consistent time evolution of a plasma; simulation of a multi-species (e-,H+,H{sub 2}{sup +},H{sub 3}{sup +},H-) plasma discharge from a neutral hydrogen gas and filament-originated seed electrons; full 2-dimensional (r,z)more » 3-velocity (vr,vz,v{phi}) dynamics for all species with exact conservation of the canonical angular momentum p{phi}; detailed collision physics between charged particles and neutrals and the ability to represent multiple smooth (not stair-stepped) electrodes of arbitrary shape and voltage whose surfaces may be secondary-particle emitters (H- and e-). The status of this development is discussed in terms of its physics content and current implementation details.« less

Thermobaricity, cabbeling, and water-mass conversion

NASA Astrophysics Data System (ADS)

McDougall, Trevor J.

1987-05-01

The efficient mixing of heat and salt along neutral surfaces (by mesoscale eddies) is shown to lead to vertical advection through these neutral surfaces. This is due to the nonlinearities of the equation of state of seawater through terms like ∂2ρ/∂θ∂p (thermobaric effect) and ∂2ρ/∂ θ2 (cabbeling). Cabbeling always causes a sinking or downwelling of fluid through neutral surfaces, whereas thermobaricity can lead to a vertical velocity (relative to neutral surfaces) of either sign. In this paper it is shown that for reasonable values of the lateral scalar diffusivity (especially below a depth of 1000 m), these two processes cause vertical velocities of the order of 10-7 m s-1 through neutral surfaces (usually downward!) and cause water-mass conversion of a magnitude equal to that caused by a vertical diffusivity of 10-4 m2 s-1 (often equivalent to a negative diffusivity). Both thermobaricity and cabbeling can occur in the presence of any nonzero amount of small-scale turbulence and so will not be detected by microstructure measurements. The conservation equations for tracers are considered in a nonorthogonal coordinate frame that moves with neutral surfaces in the ocean. Since only mixing processes cause advection across neutral surfaces, it is useful to regard this vertical advection as a symptom of various mixing processes rather than as a separate physical process. It is possible to derive conservative equations for scalars that do not contain the vertical advective term explicity. In these conservation equations, the terms that represent mixing processes are substantially altered. It is argued that this form of the conservation equations is the most appropriate when considering water-mass transformation, and some examples are given of its application in the North Atlantic. It is shown that the variation of the vertical diffusivity with height does not cause water-mass transformation. Also, salt fingering is often 3-4 times more effective at changing the potential temperature of a water mass than would be implied by simply calculating the vertical derivative of the fingering heat flux.

Electronic word of mouth on twitter about physical activity in the United States: exploratory infodemiology study.

PubMed

Zhang, Ni; Campo, Shelly; Janz, Kathleen F; Eckler, Petya; Yang, Jingzhen; Snetselaar, Linda G; Signorini, Alessio

2013-11-20

Twitter is a widely used social medium. However, its application in promoting health behaviors is understudied. In order to provide insights into designing health marketing interventions to promote physical activity on Twitter, this exploratory infodemiology study applied both social cognitive theory and the path model of online word of mouth to examine the distribution of different electronic word of mouth (eWOM) characteristics among personal tweets about physical activity in the United States. This study used 113 keywords to retrieve 1 million public tweets about physical activity in the United States posted between January 1 and March 31, 2011. A total of 30,000 tweets were randomly selected and sorted based on numbers generated by a random number generator. Two coders scanned the first 16,100 tweets and yielded 4672 (29.02%) tweets that they both agreed to be about physical activity and were from personal accounts. Finally, 1500 tweets were randomly selected from the 4672 tweets (32.11%) for further coding. After intercoder reliability scores reached satisfactory levels in the pilot coding (100 tweets separate from the final 1500 tweets), 2 coders coded 750 tweets each. Descriptive analyses, Mann-Whitney U tests, and Fisher exact tests were performed. Tweets about physical activity were dominated by neutral sentiments (1270/1500, 84.67%). Providing opinions or information regarding physical activity (1464/1500, 97.60%) and chatting about physical activity (1354/1500, 90.27%) were found to be popular on Twitter. Approximately 60% (905/1500, 60.33%) of the tweets demonstrated users' past or current participation in physical activity or intentions to participate in physical activity. However, social support about physical activity was provided in less than 10% of the tweets (135/1500, 9.00%). Users with fewer people following their tweets (followers) (P=.02) and with fewer accounts that they followed (followings) (P=.04) were more likely to talk positively about physical activity on Twitter. People with more followers were more likely to post neutral tweets about physical activity (P=.04). People with more followings were more likely to forward tweets (P=.04). People with larger differences between number of followers and followings were more likely to mention companionship support for physical activity on Twitter (P=.04). Future health marketing interventions promoting physical activity should segment Twitter users based on their number of followers, followings, and gaps between the number of followers and followings. The innovative application of both marketing and public health theory to examine tweets about physical activity could be extended to other infodemiology or infoveillance studies on other health behaviors (eg, vaccinations).

Electronic Word of Mouth on Twitter About Physical Activity in the United States: Exploratory Infodemiology Study

PubMed Central

Campo, Shelly; Janz, Kathleen F; Eckler, Petya; Yang, Jingzhen; Snetselaar, Linda G; Signorini, Alessio

2013-01-01

Background Twitter is a widely used social medium. However, its application in promoting health behaviors is understudied. Objective In order to provide insights into designing health marketing interventions to promote physical activity on Twitter, this exploratory infodemiology study applied both social cognitive theory and the path model of online word of mouth to examine the distribution of different electronic word of mouth (eWOM) characteristics among personal tweets about physical activity in the United States. Methods This study used 113 keywords to retrieve 1 million public tweets about physical activity in the United States posted between January 1 and March 31, 2011. A total of 30,000 tweets were randomly selected and sorted based on numbers generated by a random number generator. Two coders scanned the first 16,100 tweets and yielded 4672 (29.02%) tweets that they both agreed to be about physical activity and were from personal accounts. Finally, 1500 tweets were randomly selected from the 4672 tweets (32.11%) for further coding. After intercoder reliability scores reached satisfactory levels in the pilot coding (100 tweets separate from the final 1500 tweets), 2 coders coded 750 tweets each. Descriptive analyses, Mann-Whitney U tests, and Fisher exact tests were performed. Results Tweets about physical activity were dominated by neutral sentiments (1270/1500, 84.67%). Providing opinions or information regarding physical activity (1464/1500, 97.60%) and chatting about physical activity (1354/1500, 90.27%) were found to be popular on Twitter. Approximately 60% (905/1500, 60.33%) of the tweets demonstrated users’ past or current participation in physical activity or intentions to participate in physical activity. However, social support about physical activity was provided in less than 10% of the tweets (135/1500, 9.00%). Users with fewer people following their tweets (followers) (P=.02) and with fewer accounts that they followed (followings) (P=.04) were more likely to talk positively about physical activity on Twitter. People with more followers were more likely to post neutral tweets about physical activity (P=.04). People with more followings were more likely to forward tweets (P=.04). People with larger differences between number of followers and followings were more likely to mention companionship support for physical activity on Twitter (P=.04). Conclusions Future health marketing interventions promoting physical activity should segment Twitter users based on their number of followers, followings, and gaps between the number of followers and followings. The innovative application of both marketing and public health theory to examine tweets about physical activity could be extended to other infodemiology or infoveillance studies on other health behaviors (eg, vaccinations). PMID:24257325

Inhibition of bone loss with surface-modulated, drug-loaded nanoparticles in an intraosseous model of prostate cancer.

PubMed

Adjei, Isaac M; Sharma, Blanka; Peetla, Chiranjeevi; Labhasetwar, Vinod

2016-06-28

Advanced-stage prostate cancer usually metastasizes to bone and is untreatable due to poor biodistribution of intravenously administered anticancer drugs to bone. In this study, we modulated the surface charge/composition of biodegradable nanoparticles (NPs) to sustain their blood circulation time and made them small enough to extravasate through the openings of the bone's sinusoidal capillaries and thus localize into marrow. NPs with a neutral surface charge, achieved by modulating the NP surface-associated emulsifier composition, were more effective at localizing to bone marrow than NPs with a cationic or anionic surface charge. These small neutral NPs (~150nm vs. the more usual ~320nm) were also ~7-fold more effective in localizing in bone marrow than large NPs. We hypothesized that NPs that effectively localize to marrow could improve NP-mediated anticancer drug delivery to sites of bone metastasis, thereby inhibiting cancer progression and preventing bone loss. In a PC-3M-luc cell-induced osteolytic intraosseous model of prostate cancer, these small neutral NPs demonstrated greater accumulation in bone within metastatic sites than in normal contralateral bone as well as co-localization with the tumor mass in marrow. Significantly, a single-dose intravenous administration of these small neutral NPs loaded with paclitaxel (PTX-NPs), but not anionic PTX-NPs, slowed the progression of bone metastasis. In addition, neutral PTX-NPs prevented bone loss, whereas animals treated with the rapid-release drug formulation Cremophor EL (PTX-CrEL) or saline (control) showed >50% bone loss. Neutral PTX-NPs did not cause acute toxicity, whereas animals treated with PTX-CrEL experienced weight loss. These results indicate that NPs with appropriate physical and sustained drug-release characteristics could be explored to treat bone metastasis, a significant clinical issue in prostate and other cancers. Copyright © 2016 Elsevier B.V. All rights reserved.

Flavor Physics in the Quark Sector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antonelli, Mario; /Frascati; Asner, David Mark

2010-08-26

In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved, apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In themore » past, observations of CP violation were confined to neutral K mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral B mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of K,D, and B mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of the status of quark flavor physics is timely. This report is the result of the work of the physicists attending the 5th CKM workshop, hosted by the University of Rome 'La Sapienza', September 9-13, 2008. It summarizes the results of the current generation of experiments that is about to be completed and it confronts these results with the theoretical understanding of the field which has greatly improved in the past decade.« less

Physical Modeling of the Processes Responsible for the Mid-Latitude Storm Enhanced Plasma Density

NASA Astrophysics Data System (ADS)

Fuller-Rowell, T. J.; Maruyama, N.; Fedrizzi, M.; Codrescu, M.; Heelis, R. A.

2016-12-01

Certain magnetic local time sectors at mid latitudes see substantial increases in plasma density in the early phases of a geomagnetic storm. The St. Patrick's Day storms of 2013 and 2015 were no exception, both producing large increases of total electron content at mid latitudes. There are theories for the build up of the storm enhanced density (SED), but can current theoretical ionosphere-thermosphere coupled models actually reproduce the response for an actual event? Not only is it necessary for the physical model to contain the appropriate physics, they also have to be forced by the correct drivers. The SED requires mid-latitude zonal transport to provide plasma stagnation in sunlight to provide the production. The theory also requires a poleward drift perpendicular to the magnetic field to elevate the plasma out of the body of the thermosphere to regions of substantially less loss rate. It is also suggested that equatorward winds are necessary to further elevate the plasma to regions of reduced loss. However, those same winds are also likely to transport molecular nitrogen rich neutral gas equatorward, potentially canceling out the benefits of the neutral circulation. Observations of mid-latitude zonal plasma flow are first analyzed to see if this first necessary ingredient is substantiated. The drift observations are then used to tune the driver to determine if, with the appropriate electric field driver, the latest physical models can reproduce the substantial plasma build up. If it can, the simulation can also be used to assess the contribution of the equatorward meridional wind; are they an asset to the plasma build up, or does the enhanced molecular species they carry counteract their benefit.

Effects of Perceptual and Conceptual Similarity in Lexical Priming of Young Children Who Stutter: Preliminary Findings

PubMed Central

Hartfield, Kia N.; Conture, Edward G.

2007-01-01

The purpose of this study was to investigate the influence of conceptual and perceptual properties of words on the speed and accuracy of lexical retrieval of children who do (CWS) and do not stutter (CWNS) during a picture-naming task. Participants consisted of 13 3- to 5-year-old CWS and the same number of CWNS. All participants had speech, language, and hearing development within normal limits, with the exception of stuttering for CWS. Both talker groups participated in a picture-naming task where they named, one at a time, computer-presented, black-on-white drawings of common age-appropriate objects. These pictures were named during four auditory priming conditions: (a) a neutral prime consisting of a tone, (b) a word prime physically related to the target word, (c) a word prime functionally related to the target word, and (d) a word prime categorically related to the target word. Speech reaction time (SRT) was measured from the offset of presentation of the picture target to the onset of participant’s verbal speech response. Results indicated that CWS were slower than CWNS across priming conditions (i.e., neutral, physical, function, category) and that the speed of lexical retrieval of CWS was more influenced by functional than perceptual aspects of target pictures named. Findings were taken to suggest that CWS tend to organize lexical information functionally more so than physically and that this tendency may relate to difficulties establishing normally fluent speech and language. PMID:17010422

Studies on ocular and parenteral application potentials of azithromycin- loaded anionic, cationic and neutral-charged emulsions.

PubMed

Tamilvanan, Shunmugaperumal; Khanum, Ramona; Senthilkumar, Sudalimuthu Ramachandran; Muthuraman, Marimuthu; Rajasekharan, Thenrajan

2013-10-01

Ocular and parenteral application potentials of azithromycin-containing, non-phospholipid-based cationic nanosized emulsion in comparison to the phospholipid-based anionic and neutral-charged nanosized emulsions were investigated. Various physical, chemical, nonclinical toxicity and antimicrobial activity studies (mean droplet diameter, surface charge, creaming index, entrapment efficiency, accelerated, long-term and freeze-thaw cycling stabilities, TLC study, modified hen's egg chorioallantoic membrane (HET-CAM) test, in vitro hemolysis test, in vitro and in vivo myotoxicity, and in vitro antimicrobial activity) were conducted for assessing the potentials of these three types of emulsions. Following autoclave sterilization, all of these emulsions exhibited a nanometer range mean particle diameter (200 ± 29 to 434 ± 13 nm). While the anionic and cationic emulsions did show high negative (-34.2 ± 1.23 mV) and positive zeta potential (42.6 ± 1.45 mV) values, the neutral-charged emulsion did not. Even with 5 freeze-thaw cycles, the cationic emulsion remained stable whereas other two emulsions underwent phase-separation. The hen's egg chorioallantoic membrane test revealed an irritation score value that was higher for the anionic emulsion than for cationic or neutral-charged emulsion. A significantly higher % hemolysis value was also noticed for the anionic emulsion when compared to the % hemolysis value of cationic emulsion (ANOVA, P ‹ 0.05). However, all of the emulsions showed a lesser intracellular creatine kinase (CK) release/plasma CK level in comparison to the positive control (phenytoin) indicating their lesser myotoxicity at the injection site . When compared to anionic and neutral-charged emulsions, the possible controlled drug release from cationic emulsion delayed the in vitro antimicrobial action against H.influenzae and S.pneumoniae.

Fully kinetic simulations of magnetic reconnection in partially ionised gases

NASA Astrophysics Data System (ADS)

Innocenti, M. E.; Jiang, W.; Lapenta, G.; Markidis, S.

2016-12-01

Magnetic reconnection has been explored for decades as a way to convert magnetic energy into kinetic energy and heat and to accelerate particles in environments as different as the solar surface, planetary magnetospheres, the solar wind, accretion disks, laboratory plasmas. When studying reconnection via simulations, it is usually assumed that the plasma is fully ionised, as it is indeed the case in many of the above-mentioned cases. There are, however, exceptions, the most notable being the lower solar atmosphere. Small ionisation fractions are registered also in the warm neutral interstellar medium, in dense interstellar clouds, in protostellar and protoplanetary accreditation disks, in tokamak edge plasmas and in ad-hoc laboratory experiments [1]. We study here how magnetic reconnection is modified by the presence of a neutral background, i.e. when the majority of the gas is not ionised. The ionised plasma is simulated with the fully kinetic Particle-In-Cell (PIC) code iPic3D [2]. Collisions with the neutral background are introduced via a Monte Carlo plug-in. The standard Monte Carlo procedure [3] is employed to account for elastic, excitation and ionization electron-neutral collisions, as well as for elastic scattering and charge exchange ion-neutral collisions. Collisions with the background introduce resistivity in an otherwise collisionless plasma and modifications of the particle distribution functions: particles (and ions at a faster rate) tend to thermalise to the background. To pinpoint the consequences of this, we compare reconnection simulations with and without background. References [1] E E Lawrence et al. Physical review letters, 110(1):015001, 2013. [2] S Markidis et al. Mathematics and Computers in Simulation, 80(7):1509-1519, 2010. [3] K Nanbu. IEEE Transactions on plasma science, 28(3):971-990, 2000.

Searching for new heavy neutral gauge bosons using vector boson fusion processes at the LHC

DOE PAGES

Flórez, Andrés; Gurrola, Alfredo; Johns, Will; ...

2017-02-01

Here, new massive resonances are predicted in many extensions to the Standard Model (SM) of particle physics and constitutes one of the most promising searches for new physics at the LHC. We present a feasibility study to search for new heavy neutral gauge bosons using vector boson fusion (VBF) processes, which become especially important as the LHC probes higher collision energies. In particular, we consider the possibility that the discovery of a Z' boson may have eluded searches at the LHC. The coupling of the Z' boson to the SM quarks can be small, and thus the Z' would notmore » be discoverable by the searches conducted thus far. In the context of a simplified phenomenological approach, we consider the Z'→ττ and Z'→μμ decay modes to show that the requirement of a dilepton pair combined with two high p T forward jets with large separation in pseudorapidity and with large dijet mass is effective in reducing SM backgrounds. The expected exclusion bounds (at 95% confidence level) are m(Z') < 1.8 TeV and m(Z')<2.5 TeV in the ττj fj f and μμj fj f channels, respectively, assuming 1000 fb –1 of 13 TeV data from the LHC. The use of the VBF topology to search for massive neutral gauge bosons provides a discovery reach with expected significances greater than 5σ (3σ) for Z' masses up to 1.4 (1.6) TeV and 2.0 (2.2) TeV in the ττj fj f and μμj fj f channels.« less

Neutral polyfluoroalkyl substances in the atmosphere over the northern South China Sea.

PubMed

Lai, Senchao; Song, Junwei; Song, Tianli; Huang, Zhijiong; Zhang, Yingyi; Zhao, Yan; Liu, Guicheng; Zheng, Junyu; Mi, Wenying; Tang, Jianhui; Zou, Shichun; Ebinghaus, Ralf; Xie, Zhiyong

2016-07-01

Neutral Polyfluoroalkyl substances (PFASs) in the atmosphere were measured during a cruise campaign over the northern South China Sea (SCS) from September to October 2013. Four groups of PFASs, i.e., fluorotelomer alcohols (FTOHs), fluorotelomer acrylates (FTAs), fluorooctane sulfonamides (FOSAs) and fluorooctane sulfonamidoethanols (FASEs), were detected in gas samples. FTOHs was the predominant PFAS group, accounting for 95.2-99.3% of total PFASs (ΣPFASs), while the other PFASs accounted for a small fraction of ΣPFASs. The concentrations of ΣPFASs ranged from 18.0 to 109.9 pg m(-3) with an average of 54.5 pg m(-3). The concentrations are comparable to those reported in other marine atmosphere. Higher concentrations of ΣPFASs were observed in the continental-influenced samples than those in other samples, pointing to the substantial contribution of anthropogenic sources. Long-range transport is suggested to be a major pathway for introducing gaseous PFASs into the atmosphere over the northern SCS. In order to further understand the fate of gaseous PFASs during transport, the atmospheric decay of neutral PFASs under the influence of reaction with OH radicals and atmospheric physical processes were estimated. Concentrations of 8:2 FTOH, 6:2 FTOH and MeFBSE from selected source region to the atmosphere over the SCS after long-range transport were predicted and compared with the observed concentrations. It suggests that the reaction with OH radicals may play an important role in the atmospheric decay of PFAS during long-range transport, especially for shorted-lived species. Moreover, the influence of atmospheric physical processes on the decay of PFAS should be further considered. Copyright © 2016 Elsevier Ltd. All rights reserved.

Spectroscopy of neutral and ionized PAHs. From laboratory studies to astronomical observations

NASA Technical Reports Server (NTRS)

Salama, Farid

2005-01-01

Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. PAHs are the best-known candidates to account for the IR emission bands (UIR bands) and PAH spectral features are now being used as new probes of the ISM. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory astrochemistry is to reproduce (in a realistic way) the physical conditions that are associated with the emission and absorption interstellar zones. An extensive laboratory program has been developed at NASA Ames to assess the physical and chemical properties of PAHs in such environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. PAHs, neutrals and ions, are expanded through a pulsed discharge nozzle (PDN) and probed with high-sensitivity cavity ringdown spectroscopy (CRDS). These laboratory experiments provide unique information on the spectra of free, cold large carbon molecules and ions in the gas phase from the ultraviolet and visible range to the near-infrared range. Intrinsic band profiles and band positions of cold gas-phase PAHs can now be measured with high-sensitivity spectroscopy and directly compared to the astronomical data. Preliminary conclusions from the comparison of the laboratory data with astronomical observations of interstellar and circumstellar environments will also be discussed.

Charge Exchange: Velocity Dependent X-ray Emission Modeling

NASA Astrophysics Data System (ADS)

Cumbee, Renata

2017-06-01

Atomic collisions play a fundamental role in astrophysics, plasma physics, and fusion physics. Here, we focus on charge exchange (CX) between hot ions and neutral atoms and molecules. Even though charge exchange calculations can provide vital information, including neutral and ion density distributions, ion temperatures, elemental abundances, and ion charge state distributions in the environments considered, both theoretical calculations and laboratory studies of these processes lack the necessary reliability and/or coverage. In order to better understand the spectra we observe in astrophysical environments in which both hot plasma and neutral gas are present, including comets, the heliosphere, supernova remnants, galaxy clusters, star forming galaxies, the outflows of starburst galaxies, and cooling flows of hot gas in the intracluster medium, a thorough CX X-ray model is needed. Included in this model should be a complete set of X-ray line ratios for relevant ion and neutral interactions for a range of energies.In this work, theoretical charge exchange emission spectra are produced using cross sections calculated with widely applied approaches including the quantum mechanical molecular orbital close coupling (QMOCC), atomic orbital close coupling (AOCC), classical trajectory Monte Carlo (CTMC), and the multichannel Landau-Zener (MCLZ) methods. When possible, theoretical data are benchmarked to experiments. Using a comprehensive, but still far from complete, CX database, new models are performed for a variety of X-ray emitting environments. In an attempt to describe the excess emission in X-rays of the starburst galaxy M82, Ne X CX line ratios are compared to line ratios observed in the region. A more complete XSPEC X-ray emission model is produced for H-like and He-like C-Al ions colliding with H and He for a range of energies; 200 to 5000 eV/u. This model is applied to the northeast rim of the Cygnus Loop supernova remnant in an attempt to determine the contribution of CX within that region.This work was partially supported by NASA grants NNX09AC46G and NNG09WF24I and accomplished with the help of many collaborators including Phillip C. Stancil, David Lyons, Patrick Mullen, and Robin L. Shelton.

Fracto-emission from graphite/epoxy composites

NASA Technical Reports Server (NTRS)

Dickinson, J. T.

1983-01-01

Fracto-emission (FE) is the emission of particles and photons during and following crack propagation. Electrons (EE), positive ions (PIE), and excited and ground state neutrals (NE) were observed. Results of a number of experiments involving principally graphite/epoxy composites and Kevlar single fibers are presented. The physical processes responsible for EE and PIE are discussed as well as FE from fiber- and particulate-reinforced composites.

Interpersonal, Nonverbal, and Small Group Communication: Abstracts of Doctoral Dissertations Published in "Dissertation Abstracts International," July through December 1982 (Vol. 43 Nos. 1 through 6).

ERIC Educational Resources Information Center

ERIC Clearinghouse on Reading and Communication Skills, Urbana, IL.

This collection of abstracts is part of a continuing series providing information on recent doctoral dissertations. The 20 titles discuss a variety of topics, including the following: (1) caregiver talk to toddlers in dyadic and polyadic care; (2) communication tactics for neutralizing verbal aggression; (3) physical attractiveness and nonverbal…

Techniques for the Detection of Faulty Packet Header Modifications

DTIC Science & Technology

2014-03-12

layer approaches to check if packets are being altered by middleboxes and were primarily developed as network neutrality analysis tools. Switzerland works...local and metropolitan area networks –specific requirements part 11: Wireless LAN medium access control (MAC) and physical layer (PHY) specifications...policy or position of the Department of Defense or the U.S. Government. Understanding, measuring, and debugging IP networks , particularly across

Deuterium velocity and temperature measurements on the DIII-D tokamak.

PubMed

Grierson, B A; Burrell, K H; Solomon, W M; Pablant, N A

2010-10-01

Newly installed diagnostic capabilities on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 46, 6114 (2002)] enable the measurement of main ion (deuterium) velocity and temperature by charge exchange recombination spectroscopy. The uncertainty in atomic physics corrections for determining the velocity is overcome by exploiting the geometrical dependence of the apparent velocity on the viewing angle with respect to the neutral beam.

DETERMINATION OF ION AND NEUTRAL LOSS COMPOSITIONS AND DECONVOLUTION OF PRODUCT ION MASS SPECTRA USING AN ORTHOGONAL ACCELERATION, TIME-OF-FLIGHT MASS SPECTROMETER AND AN ION CORRELATION PROGRAM

EPA Science Inventory

Exact masses of monoisotopic ions and the relative isotopic abundances (RIAs) of ions greater in mass by 1 and 2 Da than the monoisotopic ion are independent and complementary physical properties useful for istinguishing among ion compositions possible for a given nominal mass. U...

UV-visible spectroscopy of PAHs and PAHNs in supersonic jet. Astrophysical Implications

NASA Astrophysics Data System (ADS)

Salma, Bejaoui; Salama, Farid

2017-06-01

Polycyclic Aromatic Hydrocarbon (PAHs) molecules are attracting much attention of the astrophysical and astrochemical communities since they are ubiquitous presence in space and could survive in the harsh interstellar medium (ISM). They are proposed as plausible carriers of the still unassigned diffuse interstellar bands (DIBs) for more than two decades now. The so-called PAH - DIB proposal has been based on the abundance of PAHs in the ISM and their stability against the photo and thermo dissociation. Nitrogen is one of the most abundant elements after hydrogen, helium, and carbon [1]. PANHs exhibit spectral features similar to PAHs and may also contribute to unidentified spectral bands.To prove PAHs-DIBs hypothesis, laboratory absorption spectra of aromatic under astrophysical relevant conditions are of crucial importance to compare with the observed DIBs spectra. The most challenging task is to reproduce as closely as technically possible, the physical and chemical conditions that are present in space. Interstellar PAHs are expected to be present as free, cold, neutral molecules and/or charged species [2]. In our laboratory, comparable conditions are achieved using an excellent platform developed in NASA Ames. Our cosmic simulation chamber (COSmIC) allow the measurements of gas phase spectra of neutral and ionized interstellar PAHs analogs by associating a molecular beam with an ionizing discharge to generate a cold plasma expansion (˜ 100 K) [3]. Our approach to assign PAH as carriers of some DIBs is record the electronic spectra of cold PAHs in gas phase and systematic search for a possible correspondence in astronomical DIBs spectra. We report in this work UV-visible absorption spectra of neutral PAHs and PAHNs using the cavity ring down spectroscopy (CRDS) technique. We discuss the effect of the substitution of C-H bond(s) by a nitrogen atom(s) in spectroscopic features of PAHs and their astrophysical application.[1] L. Spitzer, 1978, Physical processes in the interstellar medium. New York Wiley-Interscience[2] F. Salama, E. Bakes, L.J. Allamandola, A.G.G.M. Tielens, Astrophys. J. 458 (1996) 621[3] L. Biennier, F. Salama, L. J. Allamandola, & J. J. Scherer, (2003) J. of Chemical Physics, 118(17), 7863-7872

Emotions while awaiting lung transplantation: A comprehensive qualitative analysis

PubMed Central

Brügger, Aurelia; Aubert, John-David

2014-01-01

Patients awaiting lung transplantation are at risk of negative emotional and physical experiences. How do they talk about emotions? Semi-structured interviews were performed (15 patients). Categorical analysis focusing on emotion-related descriptions was organized into positive–negative–neutral descriptions: for primary and secondary emotions, evaluation processes, coping strategies, personal characteristics, emotion descriptions associated with physical states, (and) contexts were listed. Patients develop different strategies to maintain positive identity and attitude, while preserving significant others from extra emotional load. Results are discussed within various theoretical and research backgrounds, in emphasizing their importance in the definition of emotional support starting from the patient’s perspective. PMID:28070345

Emotions while awaiting lung transplantation: A comprehensive qualitative analysis.

PubMed

Brügger, Aurelia; Aubert, John-David; Piot-Ziegler, Chantal

2014-07-01

Patients awaiting lung transplantation are at risk of negative emotional and physical experiences. How do they talk about emotions? Semi-structured interviews were performed (15 patients). Categorical analysis focusing on emotion-related descriptions was organized into positive-negative-neutral descriptions: for primary and secondary emotions, evaluation processes, coping strategies, personal characteristics, emotion descriptions associated with physical states, (and) contexts were listed. Patients develop different strategies to maintain positive identity and attitude, while preserving significant others from extra emotional load. Results are discussed within various theoretical and research backgrounds, in emphasizing their importance in the definition of emotional support starting from the patient's perspective.

Age, interpersonal attraction, and social interaction. A review and assessment.

PubMed

Webb, L; Delaney, J J; Young, L R

1989-03-01

This essay reviews over 40 extant research reports on attraction and aging. The review indicated that (a) perceived agreement in attitude tends to neutralize young adults' general perception of older adults as unattractive, (b) elders prefer to associate with middle-aged and older adults more than they desire to associate with younger adults, regardless of the relative physical attraction of the target individuals, and (c) elders' marital satisfaction appears to be related to perceived physical attractiveness of the husband, not the wife. The authors provide critique and analysis of the research methods employed in the reviewed studies. Avenues for further research are identified.

Lowest-energy structures and electronic properties of Na-Si binary clusters from ab initio global search.

PubMed

Sai, Linwei; Tang, Lingli; Zhao, Jijun; Wang, Jun; Kumar, Vijay

2011-11-14

The ground state structures of neutral and anionic clusters of Na(n)Si(m) (1 ≤ n ≤ 3, 1 ≤ m ≤ 11) have been determined using genetic algorithm incorporated in first principles total energy code. The size dependence of the structural and electronic properties is discussed in detail. It is found that the lowest-energy structures of Na(n)Si(m) clusters resemble those of the pure Si clusters. Interestingly, Na atoms in neutral Na(n)Si(m) clusters are usually well separated by the Si(m) skeleton, whereas Na atoms can form Na-Na bonds in some anionic clusters. The ionization potentials, adiabatic electron affinities, and photoelectron spectra are also calculated and the results compare well with the experimental data. © 2011 American Institute of Physics

The TFTR E Parallel B Spectrometer for Mass and Energy Resolved Multi-Ion Charge Exchange Diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

A.L. Roquemore; S.S. Medley

1998-01-01

The Charge Exchange Neutral Analyzer diagnostic for the Tokamak Fusion Test Reactor was designed to measure the energy distributions of both the thermal ions and the supra thermal populations arising from neutral-beam injection and ion cyclotron radio-frequency heating. These measurements yield the plasma ion temperature, as well as several other plasma parameters necessary to provide an understanding of the plasma condition and the performance of the auxiliary heating methods. For this application, a novel charge-exchange spectrometer using a dee-shaped region of parallel electric and magnetic fields was developed at the Princeton Plasma Physics Laboratory. The design and performance of thismore » spectrometer is described in detail, including the effects of exposure of the microchannel plate detector to magnetic fields, neutrons, and tritium.« less

Neutral, ion gas-phase energetics and structural properties of hydroxybenzophenones.

PubMed

Dávalos, Juan Z; Guerrero, Andrés; Herrero, Rebeca; Jimenez, Pilar; Chana, Antonio; Abboud, José Luis M; Lima, Carlos F R A C; Santos, Luís M N B F; Lago, Alexsandre F

2010-04-16

We have carried out a study of the energetics, structural, and physical properties of o-, m-, and p-hydroxybenzophenone neutral molecules, C(13)H(10)O(2), and their corresponding anions. In particular, the standard enthalpies of formation in the gas phase at 298.15 K for all of these species were determined. A reliable experimental estimation of the enthalpy associated with intramolecular hydrogen bonding in chelated species was experimentally obtained. The gas-phase acidities (GA) of benzophenones, substituted phenols, and several aliphatic alcohols are compared with the corresponding aqueous acidities (pK(a)), covering a range of 278 kJ.mol(-1) in GA and 11.4 in pK(a). A computational study of the various species shed light on structural effects and further confirmed the self-consistency of the experimental results.

Quantification of Inflight Physical Changes: Anthropometry and Neutral Body Posture (Body Measures)

NASA Technical Reports Server (NTRS)

Rajulu, Sudhakar; Young, Karen; Reid, Chris; Dirlich, Tom

2014-01-01

The goal of this study is to gather preliminary data to better understand the magnitude and variability of microgravity changes on the body. To do this, we aim to gather and document microgravity effects on body measurements. Lengths, Breadths, Depths ? Circumferences, Joint angles. To determine if/how the Neutral Body Posture (NBP) is influenced by the above factors. This will be the first time these proposed measures are collected in space. It is anticipated that body measurements will change due to microgravity and fluid shifts. This data is important so that the changes that may occur during long-duration space flight can be identified and applied to suit fit, suit sizing, workstation design, etc. for future missions in order to prevent injury and reduce crew time for altering or adjusting suits, workstations, etc.

Study of Nb2O(y) (y = 2-5) anion and neutral clusters using anion photoelectron spectroscopy and density functional theory calculations.

PubMed

Mann, Jennifer E; Waller, Sarah E; Rothgeb, David W; Jarrold, Caroline Chick

2011-09-14

A study combining anion photoelectron spectroscopy and density functional theory calculations on the transition metal suboxide series, Nb(2)O(y)(-) (y = 2-5), is described. Photoelectron spectra of the clusters are obtained, and Franck-Condon simulations using calculated anion and neutral structures and frequencies are used to evaluate the calculations and assign transitions observed in the spectra. The spectra, several of which exhibit partially resolved vibrational structure, show an increase in electron affinity with increasing cluster oxidation state. Hole-burning experiments suggest that the photoelectron spectra of both Nb(2)O(2)(-) and Nb(2)O(3)(-) have contributions from more than one structural isomer. Reasonable agreement between experiment and computational results is found among all oxides. © 2011 American Institute of Physics

Search for Production of Single Top Quarks Via tcg and tug Flavor-Changing-Neutral-Current Couplings

NASA Astrophysics Data System (ADS)

Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T.; Aguilo, E.; Ahn, S. H.; Ahsan, M.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; Anastasoaie, M.; Ancu, L. S.; Andeen, T.; Anderson, S.; Andrieu, B.; Anzelc, M. S.; Arnoud, Y.; Arov, M.; Askew, A.; Åsman, B.; Assis Jesus, A. C. S.; Atramentov, O.; Autermann, C.; Avila, C.; Ay, C.; Badaud, F.; Baden, A.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, P.; Banerjee, S.; Barberis, E.; Barfuss, A.-F.; Bargassa, P.; Baringer, P.; Barnes, C.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bauer, D.; Beale, S.; Bean, A.; Begalli, M.; Begel, M.; Belanger-Champagne, C.; Bellantoni, L.; Bellavance, A.; Benitez, J. A.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Berntzon, L.; Bertram, I.; Besançon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Binder, M.; Biscarat, C.; Blackler, I.; Blazey, G.; Blekman, F.; Blessing, S.; Bloch, D.; Bloom, K.; Boehnlein, A.; Boline, D.; Bolton, T. A.; Boos, E. E.; Borissov, G.; Bos, K.; Bose, T.; Brandt, A.; Brock, R.; Brooijmans, G.; Bross, A.; Brown, D.; Buchanan, N. J.; Buchholz, D.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Burke, S.; Burnett, T. H.; Busato, E.; Buszello, C. P.; Butler, J. M.; Calfayan, P.; Calvet, S.; Cammin, J.; Caron, S.; Carvalho, W.; Casey, B. C. K.; Cason, N. M.; Castilla-Valdez, H.; Chakrabarti, S.; Chakraborty, D.; Chan, K.; Chan, K. M.; Chandra, A.; Charles, F.; Cheu, E.; Chevallier, F.; Cho, D. K.; Choi, S.; Choudhary, B.; Christofek, L.; Christoudias, T.; Claes, D.; Clément, B.; Clément, C.; Coadou, Y.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M.-C.; Cox, B.; Crépé-Renaudin, S.; Cutts, D.; Ćwiok, M.; da Motta, H.; Das, A.; Davies, B.; Davies, G.; de, K.; de Jong, P.; de Jong, S. J.; de La Cruz-Burelo, E.; de Oliveira Martins, C.; Degenhardt, J. D.; Déliot, F.; Demarteau, M.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Diehl, H. T.; Diesburg, M.; Doidge, M.; Dominguez, A.; Dong, H.; Dudko, L. V.; Duflot, L.; Dugad, S. R.; Duggan, D.; Duperrin, A.; Dyer, J.; Dyshkant, A.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Eno, S.; Ermolov, P.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Ferapontov, A. V.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Ford, M.; Fortner, M.; Fox, H.; Fu, S.; Fuess, S.; Gadfort, T.; Galea, C. F.; Gallas, E.; Galyaev, E.; Garcia, C.; Garcia-Bellido, A.; Gavrilov, V.; Gay, P.; Geist, W.; Gelé, D.; Gerber, C. E.; Gershtein, Y.; Gillberg, D.; Ginther, G.; Gollub, N.; Gómez, B.; Goussiou, A.; Grannis, P. D.; Greenlee, H.; Greenwood, Z. D.; Gregores, E. M.; Grenier, G.; Gris, Ph.; Grivaz, J.-F.; Grohsjean, A.; Grünendahl, S.; Grünewald, M. W.; Guo, F.; Guo, J.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hadley, N. J.; Haefner, P.; Hagopian, S.; Haley, J.; Hall, I.; Hall, R. E.; Han, L.; Hanagaki, K.; Hansson, P.; Harder, K.; Harel, A.; Harrington, R.; Hauptman, J. M.; Hauser, R.; Hays, J.; Hebbeker, T.; Hedin, D.; Hegeman, J. G.; Heinmiller, J. M.; Heinson, A. P.; Heintz, U.; Hensel, C.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoeth, H.; Hohlfeld, M.; Hong, S. J.; Hooper, R.; Houben, P.; Hu, Y.; Hubacek, Z.; Hynek, V.; Iashvili, I.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffré, M.; Jain, S.; Jakobs, K.; Jarvis, C.; Jenkins, A.; Jesik, R.; Johns, K.; Johnson, C.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Juste, A.; Käfer, D.; Kahn, S.; Kajfasz, E.; Kalinin, A. M.; Kalk, J. M.; Kalk, J. R.; Kappler, S.; Karmanov, D.; Kasper, J.; Kasper, P.; Katsanos, I.; Kau, D.; Kaur, R.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. M.; Khatidze, D.; Kim, H.; Kim, T. J.; Kirby, M. H.; Klima, B.; Kohli, J. M.; Konrath, J.-P.; Kopal, M.; Korablev, V. M.; Kotcher, J.; Kothari, B.; Koubarovsky, A.; Kozelov, A. V.; Krop, D.; Kryemadhi, A.; Kuhl, T.; Kumar, A.; Kunori, S.; Kupco, A.; Kurča, T.; Kvita, J.; Lam, D.; Lammers, S.; Landsberg, G.; Lazoflores, J.; Lebrun, P.; Lee, W. M.; Leflat, A.; Lehner, F.; Lesne, V.; Leveque, J.; Lewis, P.; Li, J.; Li, L.; Li, Q. Z.; Lietti, S. M.; Lima, J. G. R.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, Z.; Lobo, L.; Lobodenko, A.; Lokajicek, M.; Lounis, A.; Love, P.; Lubatti, H. J.; Lynker, M.; Lyon, A. L.; Maciel, A. K. A.; Madaras, R. J.; Mättig, P.; Magass, C.; Magerkurth, A.; Makovec, N.; Mal, P. K.; Malbouisson, H. B.; Malik, S.; Malyshev, V. L.; Mao, H. S.; Maravin, Y.; Martin, B.; McCarthy, R.; Melnitchouk, A.; Mendes, A.; Mendoza, L.; Mercadante, P. G.; Merkin, M.; Merritt, K. W.; Meyer, A.; Meyer, J.; Michaut, M.; Miettinen, H.; Millet, T.; Mitrevski, J.; Molina, J.; Mommsen, R. K.; Mondal, N. K.; Monk, J.; Moore, R. W.; Moulik, T.; Muanza, G. S.; Mulders, M.; Mulhearn, M.; Mundal, O.; Mundim, L.; Nagy, E.; Naimuddin, M.; Narain, M.; Naumann, N. A.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Nilsen, H.; Noeding, C.; Nomerotski, A.; Novaes, S. F.; Nunnemann, T.; O'Dell, V.; O'Neil, D. C.; Obrant, G.; Ochando, C.; Oguri, V.; Oliveira, N.; Onoprienko, D.; Oshima, N.; Osta, J.; Otec, R.; Otero Y Garzón, G. J.; Owen, M.; Padley, P.; Pangilinan, M.; Parashar, N.; Park, S.-J.; Park, S. K.; Parsons, J.; Partridge, R.; Parua, N.; Patwa, A.; Pawloski, G.; Perea, P. M.; Perfilov, M.; Peters, K.; Peters, Y.; Pétroff, P.; Petteni, M.; Piegaia, R.; Piper, J.; Pleier, M.-A.; Podesta-Lerma, P. L. M.; Podstavkov, V. M.; Pogorelov, Y.; Pol, M.-E.; Pompoš, A.; Pope, B. G.; Popov, A. V.; Potter, C.; Prado da Silva, W. L.; Prosper, H. B.; Protopopescu, S.; Qian, J.; Quadt, A.; Quinn, B.; Rangel, M. S.; Rani, K. J.; Ranjan, K.; Ratoff, P. N.; Renkel, P.; Reucroft, S.; Rijssenbeek, M.; Ripp-Baudot, I.; Rizatdinova, F.; Robinson, S.; Rodrigues, R. F.; Royon, C.; Rubinov, P.; Ruchti, R.; Sajot, G.; Sánchez-Hernández, A.; Sanders, M. P.; Santoro, A.; Savage, G.; Sawyer, L.; Scanlon, T.; Schaile, D.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schieferdecker, P.; Schmitt, C.; Schwanenberger, C.; Schwartzman, A.; Schwienhorst, R.; Sekaric, J.; Sengupta, S.; Severini, H.; Shabalina, E.; Shamim, M.; Shary, V.; Shchukin, A. A.; Shivpuri, R. K.; Shpakov, D.; Siccardi, V.; Sidwell, R. A.; Simak, V.; Sirotenko, V.; Skubic, P.; Slattery, P.; Smirnov, D.; Smith, R. P.; Snow, G. R.; Snow, J.; Snyder, S.; Söldner-Rembold, S.; Sonnenschein, L.; Sopczak, A.; Sosebee, M.; Soustruznik, K.; Souza, M.; Spurlock, B.; Stark, J.; Steele, J.; Stolin, V.; Stone, A.; Stoyanova, D. A.; Strandberg, J.; Strandberg, S.; Strang, M. A.; Strauss, M.; Ströhmer, R.; Strom, D.; Strovink, M.; Stutte, L.; Sumowidagdo, S.; Svoisky, P.; Sznajder, A.; Talby, M.; Tamburello, P.; Taylor, W.; Telford, P.; Temple, J.; Tiller, B.; Tissandier, F.; Titov, M.; Tokmenin, V. V.; Tomoto, M.; Toole, T.; Torchiani, I.; Trefzger, T.; Trincaz-Duvoid, S.; Tsybychev, D.; Tuchming, B.; Tully, C.; Tuts, P. M.; Unalan, R.; Uvarov, L.; Uvarov, S.; Uzunyan, S.; Vachon, B.; van den Berg, P. J.; van Eijk, B.; van Kooten, R.; van Leeuwen, W. M.; Varelas, N.; Varnes, E. W.; Vartapetian, A.; Vasilyev, I. A.; Vaupel, M.; Verdier, P.; Vertogradov, L. S.; Verzocchi, M.; Villeneuve-Seguier, F.; Vint, P.; Vlimant, J.-R.; von Toerne, E.; Voutilainen, M.; Vreeswijk, M.; Wahl, H. D.; Wang, L.; Wang, M. H. L. S.; Warchol, J.; Watts, G.; Wayne, M.; Weber, G.; Weber, M.; Weerts, H.; Wenger, A.; Wermes, N.; Wetstein, M.; White, A.; Wicke, D.; Wilson, G. W.; Wimpenny, S. J.; Wobisch, M.; Wood, D. R.; Wyatt, T. R.; Xie, Y.; Yacoob, S.; Yamada, R.; Yan, M.; Yasuda, T.; Yatsunenko, Y. A.; Yip, K.; Yoo, H. D.; Youn, S. W.; Yu, C.; Yu, J.; Yurkewicz, A.; Zatserklyaniy, A.; Zeitnitz, C.; Zhang, D.; Zhao, T.; Zhou, B.; Zhu, J.; Zielinski, M.; Zieminska, D.; Zieminski, A.; Zutshi, V.; Zverev, E. G.

2007-11-01

We search for the production of single top quarks via flavor-changing-neutral-current couplings of a gluon to the top quark and a charm (c) or up (u) quark. We analyze 230pb-1 of lepton+jets data from pp¯ collisions at a center of mass energy of 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. We observe no significant deviation from standard model predictions, and hence set upper limits on the anomalous coupling parameters κgc/Λ and κgu/Λ, where κg define the strength of tcg and tug couplings, and Λ defines the scale of new physics. The limits at 95% C.L. are κgc/Λ<0.15TeV-1 and κgu/Λ<0.037TeV-1.

Search for a heavy neutral particle decaying into an electron and a muon using 1 fb -1 of ATLAS data

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2011-12-07

A search is presented for a high mass neutral particle that decays directly to the e < sup > ± < /sup > μ < sup > ∓ < /sup > final state. The data sample was recorded by the ATLAS detector in √ s = 7 TeV pp collisions at the LHC from March to June 2011 and corresponds to an integrated luminosity of 1.07 fb < sup > -1 < /sup > . The data are found to be consistent with the Standard Model background. The high e < sup > ± < /sup > μ < supmore » > ∓ < /sup > mass region is used to set 95% confidence level upper limits on the production of two possible new physics processes: tau sneutrinos in an R-parity violating supersymmetric model and Z'-like vector bosons in a lepton flavor violating model.« less

Meson-meson scattering: K{anti K}-thresholds and f{sub 0}(980)-a{sub 0}(980) mixing

DOE Office of Scientific and Technical Information (OSTI.GOV)

O. Krehl; R. Rapp; J. Speth

1996-09-01

The authors study the influence of mass splitting between the charged and neutral pions and kaons in the Juelich meson exchange model for {pi}{pi} and {pi}{eta} scattering. The calculations are performed in the particle basis, which permits the use of physical masses for the pseudoscalar mesons and a study of the distinct thresholds associated with the neutral and the charged kaons. Within this model the authors also investigate the isospin violation which arises from the mass splitting and an apparent violation of G-parity in {pi}{pi} scattering which stems from the coupling to the K{anti K} channel. Nonvanishing cross sections formore » {pi}{pi} {r_arrow} {pi}{sup 0}{eta} indicate a mixing of the f{sub 0}(980) and a{sub 0}(980) states.« less

Lepton Flavor Violation Induced by a Neutral Scalar at Future Lepton Colliders

NASA Astrophysics Data System (ADS)

Dev, P. S. Bhupal; Mohapatra, Rabindra N.; Zhang, Yongchao

2018-06-01

Many new physics scenarios beyond standard model often necessitate the existence of a (light) neutral scalar H , which might couple to the charged leptons in a flavor violating way, while evading all existing constraints. We show that such scalars could be effectively produced at future lepton colliders, either on shell or off shell depending on their mass, and induce lepton flavor violating (LFV) signals, i.e., e+e-→ℓα±ℓβ∓(+H ) with α ≠β . We find that a large parameter space of the scalar mass and the LFV couplings can be probed well beyond the current low-energy constraints in the lepton sector. In particular, a scalar-loop induced explanation of the long-standing muon g -2 anomaly can be directly tested in the on-shell mode.

Gender-based performance differences in an introductory physics course

NASA Astrophysics Data System (ADS)

McKinnon, Mark Lee

Cognitive research has indicated that the difference between males and females is negligible. Paradoxically, in traditionally-taught college level introductory physics courses, males have outperformed females. UC Davis' Physics 7A (the first class of a three-quarter Introduction to Physics sequence for Life-Science students), however, counters this trend since females perform similarly to males. The gender-based performance difference within the other two quarters (Physics 7B & 7C) of the radically restructured, active-learning physics sequence still echo the traditionally-taught courses. In one experiment, I modified the laboratory activity instructions of the Physics 7C course to encourage further group interaction. These modifications did not affect the gender-based performance difference. In a later experiment, I compared students' performance on different forms of assessment for certain physics concepts during the Physics 7C course. Over 500 students took weekly quizzes at different times. The students were given different quiz questions on the same topics. Several quiz questions seemed to favor males while others were more gender equitable. I highlighted comparisons between a few pairs of questions that assessed students' understanding of the same physical concept. Males tended to perform better in responding to questions that seemed to require spatial visualization. Questions that required greater understanding of the physical concept or scientific model were more gender neutral.

A solenoidal synthetic field and the non-Abelian Aharonov-Bohm effects in neutral atoms

NASA Astrophysics Data System (ADS)

Huo, Ming-Xia; Nie, Wei; Hutchinson, David A. W.; Kwek, Leong Chuan

2014-08-01

Cold neutral atoms provide a versatile and controllable platform for emulating various quantum systems. Despite efforts to develop artificial gauge fields in these systems, realizing a unique ideal-solenoid-shaped magnetic field within the quantum domain in any real-world physical system remains elusive. Here we propose a scheme to generate a ``hairline'' solenoid with an extremely small size around 1 micrometer which is smaller than the typical coherence length in cold atoms. Correspondingly, interference effects will play a role in transport. Despite the small size, the magnetic flux imposed on the atoms is very large thanks to the very strong field generated inside the solenoid. By arranging different sets of Laguerre-Gauss (LG) lasers, the generation of Abelian and non-Abelian SU(2) lattice gauge fields is proposed for neutral atoms in ring- and square-shaped optical lattices. As an application, interference patterns of the magnetic type-I Aharonov-Bohm (AB) effect are obtained by evolving atoms along a circle over several tens of lattice cells. During the evolution, the quantum coherence is maintained and the atoms are exposed to a large magnetic flux. The scheme requires only standard optical access, and is robust to weak particle interactions.

A solenoidal synthetic field and the non-Abelian Aharonov-Bohm effects in neutral atoms.

PubMed

Huo, Ming-Xia; Nie, Wei; Hutchinson, David A W; Kwek, Leong Chuan

2014-08-08

Cold neutral atoms provide a versatile and controllable platform for emulating various quantum systems. Despite efforts to develop artificial gauge fields in these systems, realizing a unique ideal-solenoid-shaped magnetic field within the quantum domain in any real-world physical system remains elusive. Here we propose a scheme to generate a "hairline" solenoid with an extremely small size around 1 micrometer which is smaller than the typical coherence length in cold atoms. Correspondingly, interference effects will play a role in transport. Despite the small size, the magnetic flux imposed on the atoms is very large thanks to the very strong field generated inside the solenoid. By arranging different sets of Laguerre-Gauss (LG) lasers, the generation of Abelian and non-Abelian SU(2) lattice gauge fields is proposed for neutral atoms in ring- and square-shaped optical lattices. As an application, interference patterns of the magnetic type-I Aharonov-Bohm (AB) effect are obtained by evolving atoms along a circle over several tens of lattice cells. During the evolution, the quantum coherence is maintained and the atoms are exposed to a large magnetic flux. The scheme requires only standard optical access, and is robust to weak particle interactions.

Three species one-dimensional kinetic model for weakly ionized plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonzalez, J., E-mail: jorge.gonzalez@upm.es; Donoso, J. M.; Tierno, S. P.

2016-06-15

A three species one-dimensional kinetic model is presented for a spatially homogeneous weakly ionized plasma subjected to the action of a time varying electric field. Planar geometry is assumed, which means that the plasma evolves in the privileged direction of the field. The energy transmitted to the electric charges is channelized to the neutrals thanks to collisions, a mechanism that influences the plasma dynamics. Charge-charge interactions have been designed as a one-dimensional collision term equivalent to the Landau operator used for fully ionized plasmas. Charge-neutral collisions are modelled by a conservative drift-diffusion operator in the Dougherty's form. The resulting setmore » of coupled integro-differential equations is solved with the stable and robust propagator integral method. This semi–analytical method feasibility accounts for non–linear effects without appealing to linearisation or simplifications, providing conservative physically meaningful solutions even for initial or emerging sharp velocity distribution function profiles. It is found that charge-neutral collisions exert a significant effect since a quite different plasma evolution arises if compared to the collisionless limit. In addition, substantial differences in the system motion are found for constant and temperature dependent collision frequencies cases.« less

Stereophysicochemical variability plots highlight conserved antigenic areas in Flaviviruses

PubMed Central

Schein, Catherine H; Zhou, Bin; Braun, Werner

2005-01-01

Background Flaviviruses, which include Dengue (DV) and West Nile (WN), mutate in response to immune system pressure. Identifying escape mutants, variant progeny that replicate in the presence of neutralizing antibodies, is a common way to identify functionally important residues of viral proteins. However, the mutations typically occur at variable positions on the viral surface that are not essential for viral replication. Methods are needed to determine the true targets of the neutralizing antibodies. Results Stereophysicochemical variability plots (SVPs), 3-D images of protein structures colored according to variability, as determined by our PCPMer program, were used to visualize residues conserved in their physical chemical properties (PCPs) near escape mutant positions. The analysis showed 1) that escape mutations in the flavivirus envelope protein are variable residues by our criteria and 2) two escape mutants found at the same position in many flaviviruses sit above clusters of conserved residues from different regions of the linear sequence. Conservation patterns in T-cell epitopes in the NS3- protease suggest a similar mechanism of immune system evasion. Conclusion The SVPs add another dimension to structurally defining the binding sites of neutralizing antibodies. They provide a useful aid for determining antigenically important regions and designing vaccines. PMID:15845145

Host Immune Response to Influenza A Virus Infection.

PubMed

Chen, Xiaoyong; Liu, Shasha; Goraya, Mohsan Ullah; Maarouf, Mohamed; Huang, Shile; Chen, Ji-Long

2018-01-01

Influenza A viruses (IAVs) are contagious pathogens responsible for severe respiratory infection in humans and animals worldwide. Upon detection of IAV infection, host immune system aims to defend against and clear the viral infection. Innate immune system is comprised of physical barriers (mucus and collectins), various phagocytic cells, group of cytokines, interferons (IFNs), and IFN-stimulated genes, which provide first line of defense against IAV infection. The adaptive immunity is mediated by B cells and T cells, characterized with antigen-specific memory cells, capturing and neutralizing the pathogen. The humoral immune response functions through hemagglutinin-specific circulating antibodies to neutralize IAV. In addition, antibodies can bind to the surface of infected cells and induce antibody-dependent cell-mediated cytotoxicity or complement activation. Although there are neutralizing antibodies against the virus, cellular immunity also plays a crucial role in the fight against IAVs. On the other hand, IAVs have developed multiple strategies to escape from host immune surveillance for successful replication. In this review, we discuss how immune system, especially innate immune system and critical molecules are involved in the antiviral defense against IAVs. In addition, we highlight how IAVs antagonize different immune responses to achieve a successful infection.

First Results from the Interstellar Boundary Explorer (IBEX) Mission

NASA Astrophysics Data System (ADS)

McComas, David J.

2010-03-01

The Interstellar Boundary Explorer (IBEX) is a Small Explorer mission designed to study the global interaction between the heliosphere and the local interstellar medium. IBEX does this by measuring energetic neutral atoms (ENAs) created by both solar wind ions and pickup ions in the solar wind when they charge exchange with cold interstellar neutrals drifting in from the interstellar medium. Because the ENAs are not magnetically confined, some of them propagate back into the inner heliosphere, where IBEX can detect them. IBEX was launched October 19th 2008, using a new launch technique that was also developed as a part of the IBEX project. The first scientific observations from IBEX were of ENAs coming from the Moon-these represented the first ever lunar ENA observations from any spacecraft and provided important information about the universal physical processes of backscatter and neutralization from complex planetary surfaces like the lunar regolith. Since then, IBEX has been collecting its first all-sky maps of heliospheric ENAs and initial direct, in situ observations of interstellar H, He, and O. At the time of this writing, these observations have been submitted and are under review for a special IBEX section of Science magazine nominally scheduled to be published in October 2009.

Studies for the loss of atomic and molecular species for Io

NASA Technical Reports Server (NTRS)

Smyth, William H.

1996-01-01

A summary is presented for research undertaken, physical insight gained, and new directives identified in this project. Significant enhancements for the SO2 neutral cloud model and its dissociative products (SO, O2, O, S) as well as its application to investigating the amount of SO2+ measured by the Voyager PLS instrument in the plasma torus inside of Io's orbit are discussed. New excitation rates for UV and visible emission lines were incorporated in the O and S neutral cloud models, and the very preliminary analysis of UV observations near Io acquired in 1992 by the Hubble Space telescope is discussed. Observations for O('D) 6300 A emission near Io, preliminary reduction of these observations, and an initial assessment of these observations are presented. The analysis of 1985 sodium eclipse and emission data for Io has been completed and is contained in a paper in the Appendix. A larger data set for 1987 sodium emission observations, which will provide a new base for more detailed future studies, is described. A preliminary discussion is also presented for the likely nature of neutral gas clouds for the outer three Galilean satellites.

Search for single top-quark production via flavour-changing neutral currents at 8 TeV with the ATLAS detector.

PubMed

Aad, G; Abbott, B; Abdallah, J; Abdinov, O; Aben, R; Abolins, M; AbouZeid, O S; Abramowicz, H; Abreu, H; Abreu, R; Abulaiti, Y; Acharya, B S; Adamczyk, L; Adams, D L; Adelman, J; Adomeit, S; Adye, T; Affolder, A A; Agatonovic-Jovin, T; Agricola, J; Aguilar-Saavedra, J A; Ahlen, S P; Ahmadov, F; Aielli, G; Akerstedt, H; Åkesson, T P A; Akimov, A V; Alberghi, G L; Albert, J; Albrand, S; Alconada Verzini, M J; Aleksa, M; Aleksandrov, I N; Alexa, C; Alexander, G; Alexopoulos, T; Alhroob, M; Alimonti, G; Alio, L; Alison, J; Alkire, S P; Allbrooke, B M M; Allport, P P; Aloisio, A; Alonso, A; Alonso, F; Alpigiani, C; Altheimer, A; Alvarez Gonzalez, B; Álvarez Piqueras, D; Alviggi, M G; Amadio, B T; Amako, K; Amaral Coutinho, Y; Amelung, C; Amidei, D; Amor Dos Santos, S P; Amorim, A; Amoroso, S; Amram, N; Amundsen, G; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, G; Anders, J K; Anderson, K J; Andreazza, A; Andrei, V; Angelidakis, S; Angelozzi, I; Anger, P; Angerami, A; Anghinolfi, F; Anisenkov, A V; Anjos, N; Annovi, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F; Aoki, M; Aperio Bella, L; Arabidze, G; Arai, Y; Araque, J P; Arce, A T H; Arduh, F A; Arguin, J-F; Argyropoulos, S; Arik, M; Armbruster, A J; Arnaez, O; Arnal, V; Arnold, H; Arratia, M; Arslan, O; Artamonov, A; Artoni, G; Asai, S; Asbah, N; Ashkenazi, A; Åsman, B; Asquith, L; Assamagan, K; Astalos, R; Atkinson, M; Atlay, N B; Augsten, K; Aurousseau, M; Avolio, G; Axen, B; Ayoub, M K; Azuelos, G; Baak, M A; Baas, A E; Baca, M J; Bacci, C; Bachacou, H; Bachas, K; Backes, M; Backhaus, M; Bagiacchi, P; Bagnaia, P; Bai, Y; Bain, T; Baines, J T; Baker, O K; Baldin, E M; Balek, P; Balestri, T; Balli, F; Banas, E; Banerjee, Sw; Bannoura, A A E; Bansil, H S; Barak, L; Barberio, E L; Barberis, D; Barbero, M; Barillari, T; Barisonzi, M; Barklow, T; Barlow, N; Barnes, S L; Barnett, B M; Barnett, R M; Barnovska, Z; Baroncelli, A; Barone, G; Barr, A J; Barreiro, F; Barreiro Guimarães da Costa, J; Bartoldus, R; 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Vranjes Milosavljevic, M; Vrba, V; Vreeswijk, M; Vuillermet, R; Vukotic, I; Vykydal, Z; Wagner, P; Wagner, W; Wahlberg, H; Wahrmund, S; Wakabayashi, J; Walder, J; Walker, R; Walkowiak, W; Wang, C; Wang, F; Wang, H; Wang, H; Wang, J; Wang, J; Wang, K; Wang, R; Wang, S M; Wang, T; Wang, T; Wang, X; Wanotayaroj, C; Warburton, A; Ward, C P; Wardrope, D R; Washbrook, A; Wasicki, C; Watkins, P M; Watson, A T; Watson, I J; Watson, M F; Watts, G; Watts, S; Waugh, B M; Webb, S; Weber, M S; Weber, S W; Webster, J S; Weidberg, A R; Weinert, B; Weingarten, J; Weiser, C; Weits, H; Wells, P S; Wenaus, T; Wengler, T; Wenig, S; Wermes, N; Werner, M; Werner, P; Wessels, M; Wetter, J; Whalen, K; Wharton, A M; White, A; White, M J; White, R; White, S; Whiteson, D; Wickens, F J; Wiedenmann, W; Wielers, M; Wienemann, P; Wiglesworth, C; Wiik-Fuchs, L A M; Wildauer, A; Wilkens, H G; Williams, H H; Williams, S; Willis, C; Willocq, S; Wilson, A; Wilson, J A; Wingerter-Seez, I; Winklmeier, F; Winter, B T; Wittgen, M; Wittkowski, J; Wollstadt, S J; Wolter, M W; Wolters, H; Wosiek, B K; Wotschack, J; Woudstra, M J; Wozniak, K W; Wu, M; Wu, M; Wu, S L; Wu, X; Wu, Y; Wyatt, T R; Wynne, B M; Xella, S; Xu, D; Xu, L; Yabsley, B; Yacoob, S; Yakabe, R; Yamada, M; Yamaguchi, D; Yamaguchi, Y; Yamamoto, A; Yamamoto, S; Yamanaka, T; Yamauchi, K; Yamazaki, Y; Yan, Z; Yang, H; Yang, H; Yang, Y; Yao, W-M; Yasu, Y; Yatsenko, E; Yau Wong, K H; Ye, J; Ye, S; Yeletskikh, I; Yen, A L; Yildirim, E; Yorita, K; Yoshida, R; Yoshihara, K; Young, C; Young, C J S; Youssef, S; Yu, D R; Yu, J; Yu, J M; Yu, J; Yuan, L; Yuen, S P Y; Yurkewicz, A; Yusuff, I; Zabinski, B; Zaidan, R; Zaitsev, A M; Zalieckas, J; Zaman, A; Zambito, S; Zanello, L; Zanzi, D; Zeitnitz, C; Zeman, M; Zemla, A; Zeng, Q; Zengel, K; Zenin, O; Ženiš, T; Zerwas, D; Zhang, D; Zhang, F; Zhang, H; Zhang, J; Zhang, L; Zhang, R; Zhang, X; Zhang, Z; Zhao, X; Zhao, Y; Zhao, Z; Zhemchugov, A; Zhong, J; Zhou, B; Zhou, C; Zhou, L; Zhou, L; Zhou, M; Zhou, N; Zhu, C G; Zhu, H; Zhu, J; Zhu, Y; Zhuang, X; Zhukov, K; Zibell, A; Zieminska, D; Zimine, N I; Zimmermann, C; Zimmermann, S; Zinonos, Z; Zinser, M; Ziolkowski, M; Živković, L; Zobernig, G; Zoccoli, A; Zur Nedden, M; Zurzolo, G; Zwalinski, L

A search for single top-quark production via flavour-changing neutral current processes from gluon plus up- or charm-quark initial states in proton-proton collisions at the LHC is presented. Data collected with the ATLAS detector in 2012 at a centre-of-mass energy of 8 TeV and corresponding to an integrated luminosity of 20.3 fb[Formula: see text] are used. Candidate events for a top quark decaying into a lepton, a neutrino and a jet are selected and classified into signal- and background-like candidates using a neural network. No signal is observed and an upper limit on the production cross-section multiplied by the [Formula: see text] branching fraction is set. The observed 95 % CL limit is [Formula: see text] and the expected 95 % CL limit is [Formula: see text]. The observed limit can be interpreted as upper limits on the coupling constants of the flavour-changing neutral current interactions divided by the scale of new physics [Formula: see text] and [Formula: see text] and on the branching fractions [Formula: see text] and [Formula: see text].

Analysis of heavy oils: Method development and application to Cerro Negro heavy petroleum

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1989-12-01

On March 6, 1980, the US Department of Energy (DOE) and the Ministry of Energy and Mines of Venezuela (MEMV) entered into a joint agreement which included analysis of heavy crude oils from the Venezuelan Orinoco oil belt. The purpose of this report is to present compositional data and describe new analytical methods obtained from work on the Cerro Negro Orinoco belt crude oil since 1980. Most of the chapters focus on the methods rather than the resulting data on Cerro Negro oil, and results from other oils obtained during the verification of the method are included. In addition, publishedmore » work on analysis of heavy oils, tar sand bitumens, and like materials is reviewed, and the overall state of the art in analytical methodology for heavy fossil liquids is assessed. The various phases of the work included: distillation and determination of routine'' physical/chemical properties (Chapter 1); preliminary separation of >200{degrees} C distillates and the residue into acid, base, neutral, saturated hydrocarbon and neutral-aromatic concentrates (Chapter 2); further separation of acid, base, and neutral concentrates into subtypes (Chapters 3--5); and determination of the distribution of metal-containing compounds in all fractions (Chapter 6).« less

DAMPING OF MAGNETOHYDRODYNAMIC TURBULENCE IN PARTIALLY IONIZED PLASMA: IMPLICATIONS FOR COSMIC RAY PROPAGATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Siyao; Yan, Huirong; Lazarian, A., E-mail: syxu@pku.edu.cn, E-mail: huirong.yan@desy.de, E-mail: lazarian@astro.wisc.edu

2016-08-01

We study the damping processes of both incompressible and compressible magnetohydrodynamic (MHD) turbulence in a partially ionized medium. We start from the linear analysis of MHD waves, applying both single-fluid and two-fluid treatments. The damping rates derived from the linear analysis are then used in determining the damping scales of MHD turbulence. The physical connection between the damping scale of MHD turbulence and the cutoff boundary of linear MHD waves is investigated. We find two branches of slow modes propagating in ions and neutrals, respectively, below the damping scale of slow MHD turbulence, and offer a thorough discussion of theirmore » propagation and dissipation behavior. Our analytical results are shown to be applicable in a variety of partially ionized interstellar medium (ISM) phases and the solar chromosphere. The importance of neutral viscosity in damping the Alfvenic turbulence in the interstellar warm neutral medium and the solar chromosphere is demonstrated. As a significant astrophysical utility, we introduce damping effects to the propagation of cosmic rays in partially ionized ISM. The important role of turbulence damping in both transit-time damping and gyroresonance is identified.« less

Mortality of zebra mussel, Dreissena polymorpha, veligers during downstream transport

USGS Publications Warehouse

Horvath, T.G.; Lamberti, G.A.

1999-01-01

1. Streams flowing from lakes which contain zebra mussels, Dreissena polymorpha, provide apparently suitable habitats for mussel colonization and downstream range expansion, yet most such streams contain few adult mussels. We postulated that mussel veligers experience high mortality during dispersal via downstream transport. They tested this hypothesis in Christiana Creek, a lake-outlet stream in south-western Michigan, U.S.A., in which adult mussel density declined exponentially with distance downstream. 2. A staining technique using neutral red was developed and tested to distinguish quickly live and dead veligers. Live and dead veligers were distinguishable after an exposure of fresh samples to 13.3 mg L-1 of neutral red for 3 h. 3. Neutral red was used to determine the proportion of live veligers in samples taken longitudinally along Christiana Creek. The proportion of live veligers (mean ?? SE) declined from 90 ?? 3% at the lake outlet to 40 ?? 8% 18 km downstream. 4. Veligers appear to be highly susceptible to damage by physical forces (e.g. shear), and therefore, mortality in turbulent streams could be an important mechanism limiting zebra mussel dispersal to downstream reaches. Predictions of zebra mussel spread and population growth should consider lake-stream linkages and high mortality in running waters.

Biophysical implications of sphingosine accumulation in membrane properties at neutral and acidic pH.

PubMed

Zupancic, Eva; Carreira, Ana C; de Almeida, Rodrigo F M; Silva, Liana C

2014-05-08

Sphingosine (Sph) is a simple lipid involved in the regulation of several biological processes. When accumulated in the late endosomal/lysosomal compartments, Sph causes changes in ion signaling and membrane trafficking, leading to the development of Niemann-Pick disease type C. Little is known about Sph interaction with other lipids in biological membranes; however, understanding the effect of Sph in the physical state of membranes might provide insights into its mode of action. Using complementary established fluorescence approaches, we show that Sph accumulation leads to the formation of Sph-enriched gel domains in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and POPC/sphingomyelin (SM)/cholesterol (Chol) model membranes. These domains are more easily formed in membrane models mimicking the neutral pH plasma membrane environment (PM) as compared to the acidic lysosomal membrane environment (LM), where higher Sph concentrations (or lower temperatures) are required. Electrophoretic light scattering measurements further revealed that in PM-raft models (POPC/SM/Chol), Sph is mainly neutral, whereas in LM models, the positive charge of Sph leads to electrostatic repulsion, reducing the Sph ability to form gel domains. Thus, formation of Sph-enriched domains in cellular membranes might be strongly regulated by Sph charge.

High Energy Density Physics and Exotic Acceleration Schemes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cowan, T.; /General Atomics, San Diego; Colby, E.

2005-09-27

The High Energy Density and Exotic Acceleration working group took as our goal to reach beyond the community of plasma accelerator research with its applications to high energy physics, to promote exchange with other disciplines which are challenged by related and demanding beam physics issues. The scope of the group was to cover particle acceleration and beam transport that, unlike other groups at AAC, are not mediated by plasmas or by electromagnetic structures. At this Workshop, we saw an impressive advancement from years past in the area of Vacuum Acceleration, for example with the LEAP experiment at Stanford. And wemore » saw an influx of exciting new beam physics topics involving particle propagation inside of solid-density plasmas or at extremely high charge density, particularly in the areas of laser acceleration of ions, and extreme beams for fusion energy research, including Heavy-ion Inertial Fusion beam physics. One example of the importance and extreme nature of beam physics in HED research is the requirement in the Fast Ignitor scheme of inertial fusion to heat a compressed DT fusion pellet to keV temperatures by injection of laser-driven electron or ion beams of giga-Amp current. Even in modest experiments presently being performed on the laser-acceleration of ions from solids, mega-amp currents of MeV electrons must be transported through solid foils, requiring almost complete return current neutralization, and giving rise to a wide variety of beam-plasma instabilities. As keynote talks our group promoted Ion Acceleration (plenary talk by A. MacKinnon), which historically has grown out of inertial fusion research, and HIF Accelerator Research (invited talk by A. Friedman), which will require impressive advancements in space-charge-limited ion beam physics and in understanding the generation and transport of neutralized ion beams. A unifying aspect of High Energy Density applications was the physics of particle beams inside of solids, which is proving to be a very important field for diverse applications such as muon cooling, fusion energy research, and ultra-bright particle and radiation generation with high intensity lasers. We had several talks on these and other subjects, and many joint sessions with the Computational group, the EM Structures group, and the Beam Generation group. We summarize our groups' work in the following categories: vacuum acceleration schemes; ion acceleration; particle transport in solids; and applications to high energy density phenomena.« less

Outdoor thermal comfort in public space in warm-humid Guayaquil, Ecuador

NASA Astrophysics Data System (ADS)

Johansson, Erik; Yahia, Moohammed Wasim; Arroyo, Ivette; Bengs, Christer

2018-03-01

The thermal environment outdoors affects human comfort and health. Mental and physical performance is reduced at high levels of air temperature being a problem especially in tropical climates. This paper deals with human comfort in the warm-humid city of Guayaquil, Ecuador. The main aim was to examine the influence of urban micrometeorological conditions on people's subjective thermal perception and to compare it with two thermal comfort indices: the physiologically equivalent temperature (PET) and the standard effective temperature (SET*). The outdoor thermal comfort was assessed through micrometeorological measurements of air temperature, humidity, mean radiant temperature and wind speed together with a questionnaire survey consisting of 544 interviews conducted in five public places of the city during both the dry and rainy seasons. The neutral and preferred values as well as the upper comfort limits of PET and SET* were determined. For both indices, the neutral values and upper thermal comfort limits were lower during the rainy season, whereas the preferred values were higher during the rainy season. Regardless of season, the neutral values of PET and SET* are above the theoretical neutral value of each index. The results show that local people accept thermal conditions which are above acceptable comfort limits in temperate climates and that the subjective thermal perception varies within a wide range. It is clear, however, that the majority of the people in Guayaquil experience the outdoor thermal environment during daytime as too warm, and therefore, it is important to promote an urban design which creates shade and ventilation.

Spatial Distribution of Io's Neutral Oxygen Cloud Observed by Hisaki

NASA Astrophysics Data System (ADS)

Koga, Ryoichi; Tsuchiya, Fuminori; Kagitani, Masato; Sakanoi, Takeshi; Yoneda, Mizuki; Yoshioka, Kazuo; Yoshikawa, Ichiro; Kimura, Tomoki; Murakami, Go; Yamazaki, Atsushi; Smith, H. Todd; Bagenal, Fran

2018-05-01

We report on the spatial distribution of a neutral oxygen cloud surrounding Jupiter's moon Io and along Io's orbit observed by the Hisaki satellite. Atomic oxygen and sulfur in Io's atmosphere escape from the exosphere mainly through atmospheric sputtering. Some of the neutral atoms escape from Io's gravitational sphere and form neutral clouds around Jupiter. The extreme ultraviolet spectrograph called EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics) installed on the Japan Aerospace Exploration Agency's Hisaki satellite observed the Io plasma torus continuously in 2014-2015, and we derived the spatial distribution of atomic oxygen emissions at 130.4 nm. The results show that Io's oxygen cloud is composed of two regions, namely, a dense region near Io and a diffuse region with a longitudinally homogeneous distribution along Io's orbit. The dense region mainly extends on the leading side of Io and inside of Io's orbit. The emissions spread out to 7.6 Jupiter radii (RJ). Based on Hisaki observations, we estimated the radial distribution of the atomic oxygen number density and oxygen ion source rate. The peak atomic oxygen number density is 80 cm-3, which is spread 1.2 RJ in the north-south direction. We found more oxygen atoms inside Io's orbit than a previous study. We estimated the total oxygen ion source rate to be 410 kg/s, which is consistent with the value derived from a previous study that used a physical chemistry model based on Hisaki observations of ultraviolet emission ions in the Io plasma torus.

Outdoor thermal comfort in public space in warm-humid Guayaquil, Ecuador.

PubMed

Johansson, Erik; Yahia, Moohammed Wasim; Arroyo, Ivette; Bengs, Christer

2018-03-01

The thermal environment outdoors affects human comfort and health. Mental and physical performance is reduced at high levels of air temperature being a problem especially in tropical climates. This paper deals with human comfort in the warm-humid city of Guayaquil, Ecuador. The main aim was to examine the influence of urban micrometeorological conditions on people's subjective thermal perception and to compare it with two thermal comfort indices: the physiologically equivalent temperature (PET) and the standard effective temperature (SET*). The outdoor thermal comfort was assessed through micrometeorological measurements of air temperature, humidity, mean radiant temperature and wind speed together with a questionnaire survey consisting of 544 interviews conducted in five public places of the city during both the dry and rainy seasons. The neutral and preferred values as well as the upper comfort limits of PET and SET* were determined. For both indices, the neutral values and upper thermal comfort limits were lower during the rainy season, whereas the preferred values were higher during the rainy season. Regardless of season, the neutral values of PET and SET* are above the theoretical neutral value of each index. The results show that local people accept thermal conditions which are above acceptable comfort limits in temperate climates and that the subjective thermal perception varies within a wide range. It is clear, however, that the majority of the people in Guayaquil experience the outdoor thermal environment during daytime as too warm, and therefore, it is important to promote an urban design which creates shade and ventilation.

High degree of genetic differentiation in marine three-spined sticklebacks (Gasterosteus aculeatus).

PubMed

Defaveri, Jacquelin; Shikano, Takahito; Shimada, Yukinori; Merilä, Juha

2013-09-01

Populations of widespread marine organisms are typically characterized by a low degree of genetic differentiation in neutral genetic markers, but much less is known about differentiation in genes whose functional roles are associated with specific selection regimes. To uncover possible adaptive population divergence and heterogeneous genomic differentiation in marine three-spined sticklebacks (Gasterosteus aculeatus), we used a candidate gene-based genome-scan approach to analyse variability in 138 microsatellite loci located within/close to (<6 kb) functionally important genes in samples collected from ten geographic locations. The degree of genetic differentiation in markers classified as neutral or under balancing selection-as determined with several outlier detection methods-was low (F(ST) = 0.033 or 0.011, respectively), whereas average FST for directionally selected markers was significantly higher (F(ST) = 0.097). Clustering analyses provided support for genomic and geographic heterogeneity in selection: six genetic clusters were identified based on allele frequency differences in the directionally selected loci, whereas four were identified with the neutral loci. Allelic variation in several loci exhibited significant associations with environmental variables, supporting the conjecture that temperature and salinity, but not optic conditions, are important drivers of adaptive divergence among populations. In general, these results suggest that in spite of the high degree of physical connectivity and gene flow as inferred from neutral marker genes, marine stickleback populations are strongly genetically structured in loci associated with functionally relevant genes. © 2013 John Wiley & Sons Ltd.

Negative ageing stereotypes in students and faculty members from three health science schools.

PubMed

León, Soraya; Correa-Beltrán, Gloria; Giacaman, Rodrigo A

2015-06-01

To explore the ageing stereotypes held by health students and faculty members in three health science schools in Chile. This cross-sectional study surveyed 284 students and faculty members from the dental, physical therapy and speech therapy schools of the University of Talca, Chile. A validated 15-question questionnaire about negative stereotypes was used (CENVE). The questions were divided into three categories: (i) health, (ii) social factors and motivation and (iii) character and personality. The scores for each category were grouped into the following categories: (i) positive, (ii) neutral and (iii) negative. Negative stereotypes were compared across genders, socio-economic status levels, classes, positions (student or faculty member) and schools. The majority of the participants held neutral stereotypes towards ageing, followed by positive perceptions. No differences were detected between the genders, schools or classes. While most of the students had neutral perceptions about ageing, the faculty's perceptions were rather positive (p = 0.0182). In addition, people of lower-middle socio-economic status held more positive stereotypes about ageing than the participants of high and middle status (p = 0.0496). Stereotypes about ageing held by health-related students and faculty members appear to be rather neutral. The stereotypes seem to be better among students with some clinical experience, students of lower socio-economic status and faculty members. © 2013 John Wiley & Sons A/S and The Gerodontology Society. Published by John Wiley & Sons Ltd.

How do classical particle-field systems become unstable? - The last physics problem that Ronald Davidson studied

NASA Astrophysics Data System (ADS)

Qin, Hong

2016-10-01

Many of the classical particle-field systems in (neutral and nonneutral) plasma physics and accelerator physics become unstable when the system parameters vary. How do these instabilities happen? It turns out, very interestingly, that all conservative systems become unstable by the same mechanism, i.e, the resonance between a positive- and a negative-action modes. And this is the only route that a stable system can become unstable. In this talk, I will use several examples in plasma physics and accelerator physics with finite and infinite degrees of freedom to illustrate the basic physical picture and the rigorous theoretical structure of the process. The features at the transition between stable and unstable regions in the parameter space are the fundamental characteristics of the underlying real Hamiltonian system and complex G-Hamiltonian system. The resonance between a positive- and a negative-action modes at the transition is the Krein collision well-known to mathematicians. Research supported by the U.S. Department of Energy (DE-AC02-09CH11466).

Towards the identification of new physics through quark flavour violating processes.

PubMed

Buras, Andrzej J; Girrbach, Jennifer

2014-08-01

We outline a systematic strategy that should help in this decade to identify new physics (NP) beyond the standard model (SM) by means of quark flavour violating processes, and thereby extend the picture of short distance physics down to scales as short as 10(-20) m and even shorter distance scales corresponding to energies of 100 TeV. Rather than using all of the possible flavour-violating observables that will be measured in the coming years at the LHC, SuperKEKB and in Kaon physics dedicated experiments at CERN, J-PARC and Fermilab, we concentrate on those observables that are theoretically clean and very sensitive to NP. Assuming that the data on the selected observables will be very precise, we stress the importance of correlations between these observables as well as of future precise calculations of non-perturbative parameters by means of lattice QCD simulations with dynamical fermions. Our strategy consists of twelve steps, which we will discuss in detail while illustrating the possible outcomes with the help of the SM, models with constrained minimal flavour violation (CMFV), MFV at large and models with tree-level flavour changing neutral currents mediated by neutral gauge bosons and scalars. We will also briefly summarize the status of a number of concrete models. We propose DNA charts that exhibit correlations between flavour observables in different NP scenarios. Models with new left-handed and/or right-handed currents and non-MFV interactions can be distinguished transparently in this manner. We emphasize the important role of the stringent CMFV relations between various observables as standard candles of flavour physics. The pattern of deviations from these relations may help in identifying the correct NP scenario. The success of this program will be very much facilitated through direct signals of NP at the LHC, even if the LHC will not be able to probe the physics at scales shorter than 4 × 10(-20) m. We also emphasize the importance of lepton flavour violation, electric dipole moments, and (g - 2)e, μ in these studies.

Interfering with the neutron spin

NASA Astrophysics Data System (ADS)

Wagh, Apoorva G.; Rakhecha, Veer Chand

2004-07-01

Charge neutrality, a spin frac{1}{2} and an associated magnetic moment of the neu- tron make it an ideal probe of quantal spinor evolutions. Polarized neutron interferometry in magnetic field Hamiltonians has thus scored several firsts such as direct verification of Pauli anticommutation, experimental separation of geometric and dynamical phases and observation of non-cyclic amplitudes and phases. This paper provides a flavour of the physics learnt from such experiments.

Magician Simulator. A Realistic Simulator for Heterogenous Teams of Autonomous Robots

DTIC Science & Technology

2011-01-18

IMU, and LIDAR systems for identifying and tracking mobile OOI at long range (>20m), providing early warnings and allowing neutralization from a... LIDAR and Computer Vision template-based feature tracking approaches. Mapping was solved through Multi-Agent particle-filter based Simultaneous...Locali- zation and Mapping ( SLAM ). Our system contains two maps, a physical map and an influence map (location of hostile OOI, explored and unexplored

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gronke, M.; Dijkstra, M., E-mail: maxbg@astro.uio.no

We perform Lyman- α (Ly α ) Monte-Carlo radiative transfer calculations on a suite of 2500 models of multiphase, outflowing media, which are characterized by 14 parameters. We focus on the Ly α spectra emerging from these media and investigate which properties are dominant in shaping the emerging Ly α profile. Multiphase models give rise to a wide variety of emerging spectra, including single-, double-, and triple-peaked spectra. We find that the dominant parameters in shaping the spectra include (i) the cloud covering factor, f {sub c} , which is in agreement with earlier studies, and (ii) the temperature andmore » number density of residual H i in the hot ionized medium. We attempt to reproduce spectra emerging from multiphase models with “shell models” which are commonly used to fit observed Ly α spectra, and investigate the connection between shell-model parameters and the physical parameters of the clumpy media. In shell models, the neutral hydrogen content of the shell is one of the key parameters controlling Ly α radiative transfer. Because Ly α spectra emerging from multiphase media depend much less on the neutral hydrogen content of the clumps, the shell-model parameters such as H i column density (but also shell velocity and dust content) are generally not well matched to the associated physical parameters of the clumpy media.« less

Attosecond vacuum UV coherent control of molecular dynamics

PubMed Central

Ranitovic, Predrag; Hogle, Craig W.; Rivière, Paula; Palacios, Alicia; Tong, Xiao-Ming; Toshima, Nobuyuki; González-Castrillo, Alberto; Martin, Leigh; Martín, Fernando; Murnane, Margaret M.; Kapteyn, Henry

2014-01-01

High harmonic light sources make it possible to access attosecond timescales, thus opening up the prospect of manipulating electronic wave packets for steering molecular dynamics. However, two decades after the birth of attosecond physics, the concept of attosecond chemistry has not yet been realized; this is because excitation and manipulation of molecular orbitals requires precisely controlled attosecond waveforms in the deep UV, which have not yet been synthesized. Here, we present a unique approach using attosecond vacuum UV pulse-trains to coherently excite and control the outcome of a simple chemical reaction in a deuterium molecule in a non-Born–Oppenheimer regime. By controlling the interfering pathways of electron wave packets in the excited neutral and singly ionized molecule, we unambiguously show that we can switch the excited electronic state on attosecond timescales, coherently guide the nuclear wave packets to dictate the way a neutral molecule vibrates, and steer and manipulate the ionization and dissociation channels. Furthermore, through advanced theory, we succeed in rigorously modeling multiscale electron and nuclear quantum control in a molecule. The observed richness and complexity of the dynamics, even in this very simplest of molecules, is both remarkable and daunting, and presents intriguing new possibilities for bridging the gap between attosecond physics and attochemistry. PMID:24395768

Social Pavlovian conditioning: Short- and long-term effects and the role of anxiety and depressive symptoms

PubMed Central

Wilhelm, Frank H.; Boger, Sabrina; Georgii, Claudio; Klimesch, Wolfgang; Blechert, Jens

2017-01-01

Abstract Today’s stressors largely arise from social interactions rather than from physical threat. However, the dominant laboratory model of emotional learning relies on physical stimuli (e.g. electric shock) whereas adequate models of social conditioning are missing, possibly due to more subtle and multilayered biobehavioral responses to such stimuli. To fill this gap, we acquired a broad set of measures during conditioning to negative social unconditioned stimuli, also taking into account long-term maintenance of conditioning and inter-individual differences. Fifty-nine healthy participants underwent a classical conditioning task with videos of actors expressing disapproving (US-neg) or neutral (US-neu) statements. Static images of the corresponding actors with a neutral facial expression served as CS+ and CS−, predicting US-neg and US-neu, respectively. Autonomic and facial-muscular measures confirmed differential unconditioned responding whereas experiential CS ratings, event-related potentials, and evoked theta oscillations confirmed differential conditioned responding. Conditioning was maintained at 1 month and 1 year follow-ups on experiential ratings, especially in individuals with elevated anxiety and depressive symptoms, documenting the efficiency of social conditioning and its clinical relevance. This novel, ecologically improved conditioning paradigm uncovered a remarkably efficient multi-layered social learning mechanism that may represent a risk factor for anxiety and depression. PMID:27614767

Spectral emission measurements of lithium on the lithium tokamak experiment.

PubMed

Gray, T K; Biewer, T M; Boyle, D P; Granstedt, E M; Kaita, R; Maingi, R; Majeski, R P

2012-10-01

There has been a long-standing collaboration between ORNL and PPPL on edge and boundary layer physics. As part of this collaboration, ORNL has a large role in the instrumentation and interpretation of edge physics in the lithium tokamak experiment (LTX). In particular, a charge exchange recombination spectroscopy (CHERS) diagnostic is being designed and undergoing staged testing on LTX. Here we present results of passively measured lithium emission at 5166.89 A in LTX in anticipation of active spectroscopy measurements, which will be enabled by the installation of a neutral beam in 2013. Preliminary measurements are made in transient LTX plasmas with plasma current, I(p) < 70 kA, ohmic heating power, P(oh) ∼ 0.3 MW and discharge lifetimes of 10-15 ms. Measurements are made with a short focal length spectrometer and optics similar to the CHERS diagnostics on NSTX [R. E. Bell, Rev. Sci. Instrum. 68(2), 1273-1280 (1997)]. These preliminary measurements suggest that even without the neutral beam for active spectroscopy, there is sufficient passive lithium emission to allow for line-of-sight profile measurements of ion temperature, T(i); toroidal velocity and v(t). Results show peak T(i) = 70 eV and peak v(t) = 45 km/s were reached 10 ms into the discharge.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gray, T. K.; Biewer, T. M.; Maingi, R.

There has been a long-standing collaboration between ORNL and PPPL on edge and boundary layer physics. As part of this collaboration, ORNL has a large role in the instrumentation and interpretation of edge physics in the lithium tokamak experiment (LTX). In particular, a charge exchange recombination spectroscopy (CHERS) diagnostic is being designed and undergoing staged testing on LTX. Here we present results of passively measured lithium emission at 5166.89 A in LTX in anticipation of active spectroscopy measurements, which will be enabled by the installation of a neutral beam in 2013. Preliminary measurements are made in transient LTX plasmas withmore » plasma current, I{sub p} < 70 kA, ohmic heating power, P{sub oh}{approx} 0.3 MW and discharge lifetimes of 10-15 ms. Measurements are made with a short focal length spectrometer and optics similar to the CHERS diagnostics on NSTX [R. E. Bell, Rev. Sci. Instrum. 68(2), 1273-1280 (1997)]. These preliminary measurements suggest that even without the neutral beam for active spectroscopy, there is sufficient passive lithium emission to allow for line-of-sight profile measurements of ion temperature, T{sub i}; toroidal velocity and v{sub t}. Results show peak T{sub i} = 70 eV and peak v{sub t} = 45 km/s were reached 10 ms into the discharge.« less

A coupled ion-neutral photochemical model for the Titan atmosphere

NASA Astrophysics Data System (ADS)

Vuitton, V.; Yelle, R. V.; Klippenstein, S. J.; Horst, S. M.; Lavvas, P.

2013-12-01

Recent observations from the Cassini-Huygens spacecraft and the Herschel space observatory drastically increased our knowledge of Titan's chemical composition. The combination of data retrieved by Cassini INMS, UVIS, and CIRS allows deriving the vertical profiles of half a dozen species from 1000 to 100 km, while the HIFI instrument on Herschel reported on the first identification of HNC. Partial data or upper limits are available for almost 20 other CHON neutral species. The INMS and CAPS instruments onboard Cassini also revealed the existence of numerous positive and negative ions in Titan's upper atmosphere. We present the results of a 1D coupled ion-neutral photochemical model intended for the interpretation of the distribution of gaseous species in the Titan atmosphere. The model extends from the surface to the exobase. The atmospheric background, boundary conditions, vertical transport and aerosol opacity are all constrained by the Cassini-Huygens observations. The chemical network includes reactions between hydrocarbons, nitrogen and oxygen bearing species (including some species containing both nitrogen and oxygen, such as NO). It takes into account neutrals and both positive and negative ions with m/z extending up to about 100 u. Ab initio Transition State Theory calculations are performed in order to evaluate the rate coefficients and products for critical reactions. The production of minor nitrogen-bearing species and hydrocarbons is initiated by the dissociation and ionization of N2 and CH4 by solar VUV/EUV photons and associated photoelectrons in the upper atmosphere. We incorporate new high-resolution isotopic photoabsorption and photodissociation cross sections for N2 as well as new photodissociation branching ratios for CH4 and C2H2. The photodissociation of hydrocarbon radicals is taken into account and its impact on the chemistry is discussed for the first time. The presence of oxygen-bearing species is explained by an influx of oxygen originating from Enceladus in the upper atmosphere. The calculated vertical profiles of neutral and ion species generally agree with the existing observational data; some differences are highlighted. We discuss the chemical and physical processes responsible for the production and loss of some key species. We find that the production of neutral species in the upper atmosphere from electron-ion recombination reactions and neutral-neutral radiative association reactions is significant. In the stratosphere, the vertical profile of (cyano)polyynes is extremely sensitive to their heterogeneous loss on aerosols, a process that remains to be constrained experimentally and/or theoretically. This work was performed in the framework of the Marie Curie International Research Staff Exchange Scheme PIRSES-GA-2009-247509.

Perceptual Modification of the Built Environment to Influence Behavior Associated with Physical Activity: Quasi-Experimental Field Studies of a Stair Banister Illusion.

PubMed

Masters, Rich; Capio, Catherine; Poolton, Jamie; Uiga, Liis

2018-06-01

Re-engineering the built environment to influence behaviors associated with physical activity potentially provides an opportunity to promote healthier lifestyles at a population level. Here we present evidence from two quasi-experimental field studies in which we tested a novel, yet deceptively simple, intervention designed to alter perception of, and walking behavior associated with, stairs in an urban area. Our objectives were to examine whether adjusting a stair banister has an influence on perceptions of stair steepness or on walking behavior when approaching the stairs. In study 1, we asked participants (n = 143) to visually estimate the steepness of a set of stairs viewed from the top, when the stair banister was adjusted so that it converged with or diverged from the stairs (± 1.91°) or remained neutral (± 0°). In study 2, the walking behavior of participants (n = 36) was filmed as they approached the stairs to descend, unaware of whether the banister converged, diverged, or was neutral. In study 1, participants estimated the stairs to be steeper if the banister diverged from, rather than converged with, the stairs. The effect was greater when participants were unaware of the adjustment. In study 2, walking speed was significantly slower when the banister diverged from, rather than converged with, the stairs. These findings encourage us to speculate about the potential to economically re-engineer features of the built environment to provide opportunities for action (affordances) that invite physical activity behavior or even promote safer navigation of the environment.

Positive affect and physical activity: Testing effects on goal setting, activation, prioritisation, and attainment.

PubMed

Cameron, David S; Bertenshaw, Emma J; Sheeran, Paschal

2018-02-01

The present research tested whether incidental positive affect promotes pursuit of physical activity goals. Four key features of goal pursuit were examined - setting physical activity goals (Study 1), goal activation (Study 2), and goal prioritization and goal attainment (Study 3). Participants (N s = 80, 81, and 59, in Studies 1-3, respectively) were randomized to positive affect (joy, hope) or neutral affect (control) conditions in each study. Questionnaire measures of goal level, goal commitment, and means selection (Study 1); a lexical decision task indexed goal activation (Study 2), a choice task captured goal prioritization and MET minutes quantified goal attainment (Study 3). Study 1 showed that positive affect led to a greater number of intended physical activities, and that joy engendered greater willingness to try activities. In Study 2, a positive affect induction led to heightened activation of the physical activity goal compared to the control condition. The joy induction in Study 3 led to greater physical activity, and a trend towards greater goal prioritization. These findings suggest that positive affect enhances the pursuit of physical activity goals. Implications for health behavior theories and interventions are outlined.

Is the Ejecta of ETA Carinae Overabundant or Overexcited

NASA Technical Reports Server (NTRS)

Gull, Theodore; Davidson, Kris; Johansson, Sveneric; Damineli, Augusto; Ishibashi, Kaxunori; Corcoran, Michael; Hartman, Henrick; Viera, Gladys; Nielsen, Krister

2003-01-01

The ejecta of Eta Carinae, revealed by HST/STIS, are in a large range of physical conditions. As Eta Carinae undergoes a 5.52 period, changes occur in nebular emission and nebular absorption. "Warm" neutral regions, partially ionized regions, and fully ionized regions undergo significant changes. Over 2000 emission lines, most of Fe-like elements, have been indentified in the Weigelt blobs B and D. Over 500 emission lines have been indentified in the Strontium Filament. An ionized Little Homunculus is nestled within the neutral-shelled Homunculus. In line of sight, over 500 nebular absorption lines have been identified with up to twenty velocity components. STIS is following changes in many nebular emission and absorption lines as Eta Carinae approaches the minimum, predicted to be in June/July 2003, during the General Assembly. Coordinated observations with HST, CHANDRA, RXTE, FUSE, UVES/VLT, Gemini and other observatories are following this minimum.

Demixing of polymers under nanoimprinting process

NASA Astrophysics Data System (ADS)

Wang, Zhen

Polymer blend has been an important area in polymer science for decades. The knowledge of polymer blend in bulk is well established and technologies based on it have created products ubiquitous in our daily life. More intriguing problem arises when the phase separation of a polymer blend occurs under physical confinement. In this thesis, we investigated the effect of interfacial interactions between constituent polymers and confinement environment on phase evolution. Specifically, morphologies of thin films of binary polymer blends were examined on chemically homogenous substrates (preferential surface, neutral surface), on chemical pattern, between two parallel rigid substrates, and under thermal embossing/step-and-flash nanoimprint lithography conditions. We found that preferential wetting of selective component dominates the phase evolution, which can be suppressed by the use of neutral surfaces or external pressure. By manipulating these factors, a wide range of unique non-equilibrium micro or nanostructures can thus be achieved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Redi, M.H.; Mynick, H.E.; Suewattana, M.

Hamiltonian coordinate, guiding-center code calculations of the confinement of suprathermal ions in quasi-axisymmetric stellarator (QAS) designs have been carried out to evaluate the attractiveness of compact configurations which are optimized for ballooning stability. A new stellarator particle-following code is used to predict ion loss rates and particle confinement for thermal and neutral beam ions in a small experiment with R = 145 cm, B = 1-2 T and for alpha particles in a reactor-size device. In contrast to tokamaks, it is found that high edge poloidal flux has limited value in improving ion confinement in QAS, since collisional pitch-angle scatteringmore » drives ions into ripple wells and stochastic field regions, where they are quickly lost. The necessity for reduced stellarator ripple fields is emphasized. The high neutral beam ion loss predicted for these configurations suggests that more interesting physics could be explored with an experiment of less constrained size and magnetic field geometry.« less

Stability of high-mass molecular libraries: the role of the oligoporphyrin core

PubMed Central

Sezer, Uĝur; Schmid, Philipp; Felix, Lukas; Mayor, Marcel; Arndt, Markus

2015-01-01

Molecular beam techniques are a key to many experiments in physical chemistry and quantum optics. In particular, advanced matter-wave experiments with high-mass molecules profit from the availability of slow, neutral and mass-selected molecular beams that are sufficiently stable to remain intact during laser heating and photoionization mass spectrometry. We present experiments on the photostability with molecular libraries of tailored oligoporphyrins with masses up to 25 000 Da. We compare two fluoroalkylsulfanyl-functionalized libraries based on two different molecular cores that offer the same number of anchor points for functionalization but differ in their geometry and electronic properties. A pentaporphyrin core stabilizes a library of chemically well-defined molecules with more than 1600 atoms. They can be neutrally desorbed with velocities as low as 20 m/s and efficiently analyzed in photoionization mass spectrometry. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25601698

Spectroscopic interpretation and velocimetry analysis of fluctuations in a cylindrical plasma recorded by a fast camera

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oldenbuerger, S.; Brandt, C.; Brochard, F.

2010-06-15

Fast visible imaging is used on a cylindrical magnetized argon plasma produced by thermionic discharge in the Mirabelle device. To link the information collected with the camera to a physical quantity, fast camera movies of plasma structures are compared to Langmuir probe measurements. High correlation is found between light fluctuations and plasma density fluctuations. Contributions from neutral argon and ionized argon to the overall light intensity are separated by using interference filters and a light intensifier. Light emitting transitions are shown to involve a metastable neutral argon state that can be excited by thermal plasma electrons, thus explaining the goodmore » correlation between light and density fluctuations. The propagation velocity of plasma structures is calculated by adapting velocimetry methods to the fast camera movies. The resulting estimates of instantaneous propagation velocity are in agreement with former experiments. The computation of mean velocities is discussed.« less

A moiré deflectometer for antimatter

PubMed Central

Aghion, S.; Ahlén, O.; Amsler, C.; Ariga, A.; Ariga, T.; Belov, A. S.; Berggren, K.; Bonomi, G.; Bräunig, P.; Bremer, J.; Brusa, R. S.; Cabaret, L.; Canali, C.; Caravita, R.; Castelli, F.; Cerchiari, G.; Cialdi, S.; Comparat, D.; Consolati, G.; Derking, H.; Di Domizio, S.; Di Noto, L.; Doser, M.; Dudarev, A.; Ereditato, A.; Ferragut, R.; Fontana, A.; Genova, P.; Giammarchi, M.; Gligorova, A.; Gninenko, S. N.; Haider, S.; Huse, T.; Jordan, E.; Jørgensen, L. V.; Kaltenbacher, T.; Kawada, J.; Kellerbauer, A.; Kimura, M.; Knecht, A.; Krasnický, D.; Lagomarsino, V.; Lehner, S.; Magnani, A.; Malbrunot, C.; Mariazzi, S.; Matveev, V. A.; Moia, F.; Nebbia, G.; Nédélec, P.; Oberthaler, M. K.; Pacifico, N.; Petràček, V.; Pistillo, C.; Prelz, F.; Prevedelli, M.; Regenfus, C.; Riccardi, C.; Røhne, O.; Rotondi, A.; Sandaker, H.; Scampoli, P.; Storey, J.; Vasquez, M.A. Subieta; Špaček, M.; Testera, G.; Vaccarone, R.; Widmann, E.; Zavatarelli, S.; Zmeskal, J.

2014-01-01

The precise measurement of forces is one way to obtain deep insight into the fundamental interactions present in nature. In the context of neutral antimatter, the gravitational interaction is of high interest, potentially revealing new forces that violate the weak equivalence principle. Here we report on a successful extension of a tool from atom optics—the moiré deflectometer—for a measurement of the acceleration of slow antiprotons. The setup consists of two identical transmission gratings and a spatially resolving emulsion detector for antiproton annihilations. Absolute referencing of the observed antimatter pattern with a photon pattern experiencing no deflection allows the direct inference of forces present. The concept is also straightforwardly applicable to antihydrogen measurements as pursued by the AEgIS collaboration. The combination of these very different techniques from high energy and atomic physics opens a very promising route to the direct detection of the gravitational acceleration of neutral antimatter. PMID:25066810

A moiré deflectometer for antimatter.

PubMed

Aghion, S; Ahlén, O; Amsler, C; Ariga, A; Ariga, T; Belov, A S; Berggren, K; Bonomi, G; Bräunig, P; Bremer, J; Brusa, R S; Cabaret, L; Canali, C; Caravita, R; Castelli, F; Cerchiari, G; Cialdi, S; Comparat, D; Consolati, G; Derking, H; Di Domizio, S; Di Noto, L; Doser, M; Dudarev, A; Ereditato, A; Ferragut, R; Fontana, A; Genova, P; Giammarchi, M; Gligorova, A; Gninenko, S N; Haider, S; Huse, T; Jordan, E; Jørgensen, L V; Kaltenbacher, T; Kawada, J; Kellerbauer, A; Kimura, M; Knecht, A; Krasnický, D; Lagomarsino, V; Lehner, S; Magnani, A; Malbrunot, C; Mariazzi, S; Matveev, V A; Moia, F; Nebbia, G; Nédélec, P; Oberthaler, M K; Pacifico, N; Petràček, V; Pistillo, C; Prelz, F; Prevedelli, M; Regenfus, C; Riccardi, C; Røhne, O; Rotondi, A; Sandaker, H; Scampoli, P; Storey, J; Vasquez, M A Subieta; Špaček, M; Testera, G; Vaccarone, R; Widmann, E; Zavatarelli, S; Zmeskal, J

2014-07-28

The precise measurement of forces is one way to obtain deep insight into the fundamental interactions present in nature. In the context of neutral antimatter, the gravitational interaction is of high interest, potentially revealing new forces that violate the weak equivalence principle. Here we report on a successful extension of a tool from atom optics--the moiré deflectometer--for a measurement of the acceleration of slow antiprotons. The setup consists of two identical transmission gratings and a spatially resolving emulsion detector for antiproton annihilations. Absolute referencing of the observed antimatter pattern with a photon pattern experiencing no deflection allows the direct inference of forces present. The concept is also straightforwardly applicable to antihydrogen measurements as pursued by the AEgIS collaboration. The combination of these very different techniques from high energy and atomic physics opens a very promising route to the direct detection of the gravitational acceleration of neutral antimatter.

Spectroscopic interpretation and velocimetry analysis of fluctuations in a cylindrical plasma recorded by a fast camera

NASA Astrophysics Data System (ADS)

Oldenbürger, S.; Brandt, C.; Brochard, F.; Lemoine, N.; Bonhomme, G.

2010-06-01

Fast visible imaging is used on a cylindrical magnetized argon plasma produced by thermionic discharge in the Mirabelle device. To link the information collected with the camera to a physical quantity, fast camera movies of plasma structures are compared to Langmuir probe measurements. High correlation is found between light fluctuations and plasma density fluctuations. Contributions from neutral argon and ionized argon to the overall light intensity are separated by using interference filters and a light intensifier. Light emitting transitions are shown to involve a metastable neutral argon state that can be excited by thermal plasma electrons, thus explaining the good correlation between light and density fluctuations. The propagation velocity of plasma structures is calculated by adapting velocimetry methods to the fast camera movies. The resulting estimates of instantaneous propagation velocity are in agreement with former experiments. The computation of mean velocities is discussed.

The aurora and the magnetosphere - The Chapman Memorial Lecture. [dynamo theory development, 1600-present

NASA Technical Reports Server (NTRS)

Akasofu, S.-I.

1974-01-01

Review of recent progress in magnetospheric physics, in particular, in understanding the magnetospheric substorm. It is shown that a number of magnetospheric phenomena can now be understood by viewing the solar wind-magnetosphere interaction as an MHD dynamo; auroral phenomena are powered by the dynamo. Also, magnetospheric responses to variations of the north-south and east-west components of the interplanetary magnetic field have been identified. The magnetospheric substorm is entirely different from the responses of the magnetosphere to the southward component of the interplanetary magnetic field. It may be associated with the formation of a neutral line within the plasma sheet and with an enhanced reconnection along the line. A number of substorm-associated phenomena can be understood by noting that the new neutral line formation is caused by a short-circuiting of a part of the magnetotail current.

Afterimage induced neural activity during emotional face perception.

PubMed

Cheal, Jenna L; Heisz, Jennifer J; Walsh, Jennifer A; Shedden, Judith M; Rutherford, M D

2014-02-26

The N170 response differs when positive versus negative facial expressions are viewed. This neural response could be associated with the perception of emotions, or some feature of the stimulus. We used an aftereffect paradigm to clarify. Consistent with previous reports of emotional aftereffects, a neutral face was more likely to be described as happy following a sad face adaptation, and more likely to be described as sad following a happy face adaptation. In addition, similar to previous observations with actual emotional faces, we found differences in the latency of the N170 elicited by the neutral face following sad versus happy face adaptation, demonstrating that the emotion-specific effect on the N170 emerges even when emotion expressions are perceptually different but physically identical. The re-entry of emotional information from other brain regions may be driving the emotional aftereffects and the N170 latency differences. Copyright © 2014 Elsevier B.V. All rights reserved.

Search for production of single top quarks via tcg and tug flavor-changing-neutral-current couplings.

PubMed

Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Ancu, L S; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Arnoud, Y; Arov, M; Askew, A; Asman, B; Assis Jesus, A C S; Atramentov, O; Autermann, C; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, P; Banerjee, S; Barberis, E; Barfuss, A-F; Bargassa, P; Baringer, P; Barnes, C; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Berntzon, L; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Binder, M; Biscarat, C; Blackler, I; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Boos, E E; Borissov, G; Bos, K; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Buehler, M; Buescher, V; Bunichev, V; Burdin, S; Burke, S; Burnett, T H; Busato, E; Buszello, C P; Butler, J M; Calfayan, P; Calvet, S; Cammin, J; Caron, S; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K; Chan, K M; Chandra, A; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Christoudias, T; Claes, D; Clément, B; Clément, C; Coadou, Y; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Cox, B; Crépé-Renaudin, S; Cutts, D; Cwiok, M; da Motta, H; Das, A; Davies, B; Davies, G; De, K; de Jong, P; de Jong, S J; De La Cruz-Burelo, E; De Oliveira Martins, C; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Doidge, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Ford, M; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; Garcia, C; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Gelé, D; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Gollub, N; Gómez, B; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, F; Guo, J; Gutierrez, G; Gutierrez, P; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Hanagaki, K; Hansson, P; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Hong, S J; Hooper, R; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jenkins, A; Jesik, R; Johns, K; Johnson, C; Johnson, M; Jonckheere, A; Jonsson, P; Juste, A; Käfer, D; Kahn, S; Kajfasz, E; Kalinin, A M; Kalk, J M; Kalk, J R; Kappler, S; Karmanov, D; Kasper, J; Kasper, P; Katsanos, I; Kau, D; Kaur, R; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y M; Khatidze, D; Kim, H; Kim, T J; Kirby, M H; Klima, B; Kohli, J M; Konrath, J-P; Kopal, M; Korablev, V M; Kotcher, J; Kothari, B; Koubarovsky, A; Kozelov, A V; Krop, D; Kryemadhi, A; Kuhl, T; Kumar, A; Kunori, S; Kupco, A; Kurca, T; Kvita, J; Lam, D; Lammers, S; Landsberg, G; Lazoflores, J; Lebrun, P; Lee, W M; Leflat, A; Lehner, F; Lesne, V; Leveque, J; Lewis, P; Li, J; Li, L; Li, Q Z; Lietti, S M; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Z; Lobo, L; Lobodenko, A; Lokajicek, M; Lounis, A; Love, P; Lubatti, H J; Lynker, M; Lyon, A L; Maciel, A K A; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Makovec, N; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; Martin, B; McCarthy, R; Melnitchouk, A; Mendes, A; Mendoza, L; Mercadante, P G; Merkin, M; Merritt, K W; Meyer, A; Meyer, J; Michaut, M; Miettinen, H; Millet, T; Mitrevski, J; Molina, J; Mommsen, R K; Mondal, N K; Monk, J; Moore, R W; Moulik, T; Muanza, G S; Mulders, M; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Noeding, C; Nomerotski, A; Novaes, S F; Nunnemann, T; O'Dell, V; O'Neil, D C; Obrant, G; Ochando, C; Oguri, V; Oliveira, N; Onoprienko, D; Oshima, N; Osta, J; Otec, R; Otero Y Garzón, G J; Owen, M; Padley, P; Pangilinan, M; Parashar, N; Park, S-J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Perea, P M; Perfilov, M; Peters, K; Peters, Y; Pétroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M-E; Pompos, A; Pope, B G; Popov, A V; Potter, C; Prado da Silva, W L; Prosper, H B; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rangel, M S; Rani, K J; Ranjan, K; Ratoff, P N; Renkel, P; Reucroft, S; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rodrigues, R F; Royon, C; Rubinov, P; Ruchti, R; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A; Savage, G; Sawyer, L; Scanlon, T; Schaile, D; Schamberger, R D; Scheglov, Y; Schellman, H; Schieferdecker, P; Schmitt, C; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sekaric, J; Sengupta, S; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shivpuri, R K; Shpakov, D; Siccardi, V; Sidwell, R A; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Smith, R P; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Souza, M; Spurlock, B; Stark, J; Steele, J; Stolin, V; Stone, A; Stoyanova, D A; Strandberg, J; Strandberg, S; Strang, M A; Strauss, M; Ströhmer, R; Strom, D; Strovink, M; Stutte, L; Sumowidagdo, S; Svoisky, P; Sznajder, A; Talby, M; Tamburello, P; Taylor, W; Telford, P; Temple, J; Tiller, B; Tissandier, F; Titov, M; Tokmenin, V V; Tomoto, M; Toole, T; Torchiani, I; Trefzger, T; Trincaz-Duvoid, S; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, L; Uvarov, S; Uzunyan, S; Vachon, B; van den Berg, P J; van Eijk, B; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vartapetian, A; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Villeneuve-Seguier, F; Vint, P; Vlimant, J-R; Von Toerne, E; Voutilainen, M; Vreeswijk, M; Wahl, H D; Wang, L; Wang, M H L S; Warchol, J; Watts, G; Wayne, M; Weber, G; Weber, M; Weerts, H; Wenger, A; Wermes, N; Wetstein, M; White, A; Wicke, D; Wilson, G W; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Yacoob, S; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yip, K; Yoo, H D; Youn, S W; Yu, C; Yu, J; Yurkewicz, A; Zatserklyaniy, A; Zeitnitz, C; Zhang, D; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zutshi, V; Zverev, E G

2007-11-09

We search for the production of single top quarks via flavor-changing-neutral-current couplings of a gluon to the top quark and a charm (c) or up (u) quark. We analyze 230 pb{-1} of lepton+jets data from pp[over] collisions at a center of mass energy of 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. We observe no significant deviation from standard model predictions, and hence set upper limits on the anomalous coupling parameters kappa{g}{c}/Lambda and kappa{g}{u}/Lambda, where kappa{g} define the strength of tcg and tug couplings, and Lambda defines the scale of new physics. The limits at 95% C.L. are kappa{g}{c}/Lambda<0.15 TeV-1 and kappa{g}{u}/Lambda<0.037 TeV-1.

Simulation studies for the PANDA experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kopf, B.

2005-10-26

One main component of the planned Facility for Antiproton and Ion Research (FAIR) is the High Energy Storage Ring (HESR) at GSI, Darmstadt, which will provide cooled antiprotons with momenta between 1.5 and 15 GeV/c. The PANDA experiment will investigate p-barannihilations with internal hydrogen and nuclear targets. Due to the planned extensive physics program a multipurpose detector with nearly complete solid angle coverage, proper particle identification over a large momentum range, and high resolution calorimetry for neutral particles is required. For the optimization of the detector design simulation studies of several benchmark channels are in progress which are covering themore » most relevant physics topics. Some important simulation results are discussed here.« less

Penguin Decays of B Mesons

NASA Astrophysics Data System (ADS)

Lingel, Karen; Skwarnicki, Tomasz; Smith, James G.

Penguin, or loop, decays of B mesons induce effective flavor-changing neutral currents, which are forbidden at tree level in the standard model. These decays give special insight into the CKM matrix and are sensitive to non-standard-model effects. In this review, we give a historical and theoretical introduction to penguins and a description of the various types of penguin processes: electromagnetic, electroweak, and gluonic. We review the experimental searches for penguin decays, including the measurements of the electromagnetic penguins b -> sgamma and B -> K*gamma and gluonic penguins B -> Kpi, B+ -> omegaK+ and B -> eta'K, and their implications for the standard model and new physics. We conclude by exploring the future prospects for penguin physics.

Stability of a viscous fluid in a rectangular cavity in the presence of a magnetic field

NASA Technical Reports Server (NTRS)

Liang, C. Y.; Hung, Y. Y.

1976-01-01

The stability of an electrically conducting fluid subjected to two dimensional disturbance was investigated. A physical system consisting of two parallel infinite vertical plates which are thermally insulated was studied. An external magnetic field of constant strength was applied to normal plates. The fluid was heated from below so that a steady temperature gradient was maintained in the fluid. The governing equations were derived by perturbation technique, and solutions were obtained by a modified Galerkin method. It was found that the presence of the magnetic field increases the stability of the physical system and instability can occur in the form of neutral or oscillatory instability.

Ireland and the Defense of Western Europe. Issues and Implications.

DTIC Science & Technology

1988-05-01

domestic or external pressure to do so. In fact, neutrality is widely supported and could be abandoned only at a prohibitive political cost . Many...makes the costs of Irish membership outweigh any benefits? Her geographic location, as well as certain of her physical characteristics, would make her...peacetime must be weighed against the considerable costs involved. The obvious question then is, what would Ireland do in wartime? This is a question other

Selected ground-water data, Chester County, Pennsylvania

USGS Publications Warehouse

Sloto, Ronald A.

1989-01-01

Hydrologic data for Chester County, Pennsylvania are given for 3,010 wells and 32 springs. Water levels are given for 48 observation wells measured monthly during 1936-86. Chemical analyses of ground water are given for major ions, physical properties, nutrients, metals and other trace constituents, volatile organic compounds, acid organic compounds, base-neutral organic compounds, organochlorine insecticides, polychlorinated biphenyls, polychlorinated napthalenes, organophosphorous insecticides, organic acid herbicides, triazine herbicides, other organic compounds, and radionuclides.

Aged particles derived from emissions of coal-fired power plants: The TERESA field results

PubMed Central

Kang, Choong-Min; Gupta, Tarun; Ruiz, Pablo A.; Wolfson, Jack M.; Ferguson, Stephen T.; Lawrence, Joy E.; Rohr, Annette C.; Godleski, John; Koutrakis, Petros

2013-01-01

The Toxicological Evaluation of Realistic Emissions Source Aerosols (TERESA) study was carried out at three US coal-fired power plants to investigate the potential toxicological effects of primary and photochemically aged (secondary) particles using in situ stack emissions. The exposure system designed successfully simulated chemical reactions that power plant emissions undergo in a plume during transport from the stack to receptor areas (e.g., urban areas). Test atmospheres developed for toxicological experiments included scenarios to simulate a sequence of atmospheric reactions that can occur in a plume: (1) primary emissions only; (2) H2SO4 aerosol from oxidation of SO2; (3) H2SO4 aerosol neutralized by gas-phase NH3; (4) neutralized H2SO4 with secondary organic aerosol (SOA) formed by the reaction of α-pinene with O3; and (5) three control scenarios excluding primary particles. The aged particle mass concentrations varied significantly from 43.8 to 257.1 μg/m3 with respect to scenario and power plant. The highest was found when oxidized aerosols were neutralized by gas-phase NH3 with added SOA. The mass concentration depended primarily on the ratio of SO2 to NOx (particularly NO) emissions, which was determined mainly by coal composition and emissions controls. Particulate sulfate (H2SO4 + neutralized sulfate) and organic carbon (OC) were major components of the aged particles with added SOA, whereas trace elements were present at very low concentrations. Physical and chemical properties of aged particles appear to be influenced by coal type, emissions controls and the particular atmospheric scenarios employed. PMID:20462390

Direct Observations of Interstellar H, He, and O by the Interstellar Boundary Explorer (Invited)

NASA Astrophysics Data System (ADS)

Moebius, E.; Bochsler, P. A.; Bzowski, M.; Crew, G. B.; Funsten, H. O.; Fuselier, S. A.; Ghielmetti, A.; Heirtzler, D.; Izmodenov, V.; Kubiak, M.; Kucharek, H.; Lee, M. A.; Leonard, T.; McComas, D. J.; Petersen, L.; Saul, L. A.; Scheer, J.; Schwadron, N. A.; Witte, M.; Wurz, P.

2009-12-01

Due to the motion of the Sun relative to its neighborhood, the neutral gas of the local in-terstellar medium (LISM) flows through the inner heliosphere where it is subject to ioni-zation, the Sun’s gravity, and radiation pressure. Observing the resulting spatial distribu-tion and flow pattern of several interstellar gas species with UV backscatter, pickup ion, and neutral atom imaging techniques allows us to unravel the physical conditions of the LISM and its interaction with the heliosphere. Imaging of the neutral gas flow directly with energetic neutral atom (ENA) cameras yields the most accurate account of the ki-netic parameters of the interstellar gas, but so far this has been carried out only for He using Ulysses GAS. IBEX, which was launched in October 2008, provides the capability for simultaneous flow observations of several interstellar species with its triple-time-of-flight IBEX-Lo sensor. Because H and O are strongly affected by the heliospheric inter-face while He is not, a direct comparison between these species enables an independent assessment of the slowdown and heating processes in the outer heliosheath. Likewise, IBEX observations will constrain models of the heliospheric interaction and provide a test of the heliospheric asymmetry - recently inferred from Voyager and SOHO SWAN observations - that is seen as an indicator for the interstellar magnetic field direction. During the first half year of its mission IBEX has observed the interstellar He, O, and H flow. We will present an overview and preliminary analysis of these first interstellar mul-tispecies scans of the interstellar gas flow in spring and fall 2009.

What Can Galaxies Tell Us About The Epoch of Reionization?

NASA Astrophysics Data System (ADS)

Mason, Charlotte; GLASS, BoRG

2018-01-01

The reionization of neutral hydrogen in the intergalactic medium (IGM) in the universe's first billion years (z>6) was likely driven by the first stars and galaxies, and its history encodes information about their properties. But the timeline of reionization is not well-measured and it is still unclear whether galaxies alone can produce the required ionizing photons. I will describe two key ways in which galaxies at our current observational frontiers can constrain reionization.One tool is the UV luminosity function (LF), which traces the evolution of star-forming galaxies and their ionizing photons. I will describe a Bayesian technique to account for gravitational lensing magnification bias in galaxy surveys to produce accurate LFs. I will then describe a simple, but powerful, model for LF evolution and its implications for reionization and z>10 galaxy surveys with JWST. Secondly, Lyman alpha (Lya) emission from galaxies is a potential probe of the IGM ionization state as Lya photons are strongly attenuated by neutral hydrogen, but requires disentangling physics on pc to Gpc scales. I will introduce a new forward-modeling Bayesian framework which combines cosmological IGM simulations with models of interstellar medium conditions to infer the IGM neutral fraction from observations of Lya emission. I will present our new measurement of the neutral fraction at z~7 and place it in the context of other constraints of the reionization history. I will describe ongoing efforts to build larger samples of Lya emitting galaxies for more accurate measurements with the HST survey GLASS, and will describe future prospects with JWST.

Post-learning stress differentially affects memory for emotional gist and detail in naturally cycling women and women on hormonal contraceptives

PubMed Central

Nielsen, Shawn E.; Ahmed, Imran; Cahill, Larry

2014-01-01

Sex differences in emotional memory have received increasing interest over the past decade. However, to date, no work has explored how a post-learning stressor might modulate the influence of sex hormone status on memory for gist and peripheral detail in an emotional versus neutral context. Here, we tested three predictions. First, compared to naturally cycling women (NC women) in the luteal phase, women on hormonal contraception (HC women) would have significantly blunted HPA reactivity to physical stress. Second, post-learning stress would enhance detail and gist memory from an emotional story in NC women, and finally, post-learning stress would not affect emotional memory for details or gist in HC women. Healthy NC and HC women viewed a brief, narrated story containing neutral or emotionally arousing elements. Immediately after, Cold Pressor Stress (CPS) or a control procedure was administered. One week later, participants received a surprise free recall test for story elements. NC women exhibited significantly greater cortisol increases to CPS compared to HC women. NC women who viewed the emotional story and were administered CPS recalled the most peripheral details overall and more gist from the emotional compared to the neutral story. In HC women, however, the post-learning cortisol release did not affect memory for gist or peripheral details from the emotional or neutral story in any way. Additionally, NC and HC women performed similarly on measures of attention and arousal. These findings suggest that in women, post-learning stress differentially affects memory for emotional information depending on their hormonal contraceptive status. PMID:24841741

Postlearning stress differentially affects memory for emotional gist and detail in naturally cycling women and women on hormonal contraceptives.

PubMed

Nielsen, Shawn E; Ahmed, Imran; Cahill, Larry

2014-08-01

Sex differences in emotional memory have received increasing interest over the past decade. However, to date, no work has explored how a postlearning stressor might modulate the influence of sex hormone status on memory for gist and peripheral detail in an emotional versus neutral context. Here, we tested 3 predictions. First, compared with naturally cycling (NC) women in the luteal phase, women on hormonal contraception (HC) would have significantly blunted hypothalamic-pituitary-adrenal reactivity to physical stress. Second, postlearning stress would enhance detail and gist memory from an emotional story in NC women, and finally, postlearning stress would not affect emotional memory for details or gist in HC women. Healthy NC and HC women viewed a brief, narrated story containing neutral or emotionally arousing elements. Immediately after, cold pressor stress (CPS) or a control procedure was administered. One week later, participants received a surprise free recall test for story elements. NC women exhibited significantly greater cortisol increases to CPS compared with HC women. NC women who viewed the emotional story and were administered CPS recalled the most peripheral details overall and more gist from the emotional compared with the neutral story. In HC women, however, the postlearning cortisol release did not affect memory for gist or peripheral details from the emotional or neutral story in any way. Additionally, NC and HC women performed similarly on measures of attention and arousal. These findings suggest that in women, postlearning stress differentially affects memory for emotional information depending on their hormonal contraceptive status.

The measurement of consciousness: a framework for the scientific study of consciousness

PubMed Central

Gamez, David

2014-01-01

Scientists studying consciousness are attempting to identify correlations between measurements of consciousness and the physical world. Consciousness can only be measured through first-person reports, which raises problems about the accuracy of first-person reports, the possibility of non-reportable consciousness and the causal closure of the physical world. Many of these issues could be resolved by assuming that consciousness is entirely physical or functional. However, this would sacrifice the theory-neutrality that is a key attraction of a correlates-based approach to the study of consciousness. This paper puts forward a different solution that uses a framework of definitions and assumptions to explain how consciousness can be measured. This addresses the problems associated with first-person reports and avoids the issues with the causal closure of the physical world. This framework is compatible with most of the current theories of consciousness and it leads to a distinction between two types of correlates of consciousness. PMID:25071677

Indirect handle on the down-quark Yukawa coupling.

PubMed

Goertz, Florian

2014-12-31

To measure the Yukawa couplings of the up and down quarks, Yu,d, seems to be far beyond the capabilities of current and (near) future experiments in particle physics. By performing a general analysis of the potential misalignment between quark masses and Yukawa couplings, we derive predictions for the magnitude of induced flavor-changing neutral currents (FCNCs), depending on the shift in the physical Yukawa coupling of first-generation quarks. We find that a change of more than 50% in Yd would generically result in ds transitions in conflict with kaon physics. This could already be seen as evidence for a nonvanishing direct coupling of the down quark to the newly discovered Higgs boson. The nonobservation of certain--already well-constrained--processes is thus turned into a powerful indirect measure of otherwise basically unaccessible physical parameters of the effective standard model. Similarly, improvements in limits on FCNCs in the up-type quark sector can lead to valuable information on Yu.

The GBS code for tokamak scrape-off layer simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halpern, F.D., E-mail: federico.halpern@epfl.ch; Ricci, P.; Jolliet, S.

2016-06-15

We describe a new version of GBS, a 3D global, flux-driven plasma turbulence code to simulate the turbulent dynamics in the tokamak scrape-off layer (SOL), superseding the code presented by Ricci et al. (2012) [14]. The present work is driven by the objective of studying SOL turbulent dynamics in medium size tokamaks and beyond with a high-fidelity physics model. We emphasize an intertwining framework of improved physics models and the computational improvements that allow them. The model extensions include neutral atom physics, finite ion temperature, the addition of a closed field line region, and a non-Boussinesq treatment of the polarizationmore » drift. GBS has been completely refactored with the introduction of a 3-D Cartesian communicator and a scalable parallel multigrid solver. We report dramatically enhanced parallel scalability, with the possibility of treating electromagnetic fluctuations very efficiently. The method of manufactured solutions as a verification process has been carried out for this new code version, demonstrating the correct implementation of the physical model.« less

Exploration of spherical torus physics in the NSTX device

NASA Astrophysics Data System (ADS)

Ono, M.; Kaye, S. M.; Peng, Y.-K. M.; Barnes, G.; Blanchard, W.; Carter, M. D.; Chrzanowski, J.; Dudek, L.; Ewig, R.; Gates, D.; Hatcher, R. E.; Jarboe, T.; Jardin, S. C.; Johnson, D.; Kaita, R.; Kalish, M.; Kessel, C. E.; Kugel, H. W.; Maingi, R.; Majeski, R.; Manickam, J.; McCormack, B.; Menard, J.; Mueller, D.; Nelson, B. A.; Nelson, B. E.; Neumeyer, C.; Oliaro, G.; Paoletti, F.; Parsells, R.; Perry, E.; Pomphrey, N.; Ramakrishnan, S.; Raman, R.; Rewoldt, G.; Robinson, J.; Roquemore, A. L.; Ryan, P.; Sabbagh, S.; Swain, D.; Synakowski, E. J.; Viola, M.; Williams, M.; Wilson, J. R.; NSTX Team

2000-03-01

The National Spherical Torus Experiment (NSTX) is being built at Princeton Plasma Physics Laboratory to test the fusion physics principles for the spherical torus concept at the MA level. The NSTX nominal plasma parameters are R0 = 85 cm, a = 67 cm, R/a >= 1.26, Bt = 3 kG, Ip = 1 MA, q95 = 14, elongation κ <= 2.2, triangularity δ <= 0.5 and a plasma pulse length of up to 5 s. The plasma heating/current drive tools are high harmonic fast wave (6 MW, 5 s), neutral beam injection (5 MW, 80 keV, 5 s) and coaxial helicity injection. Theoretical calculations predict that NSTX should provide exciting possibilities for exploring a number of important new physics regimes, including very high plasma β, naturally high plasma elongation, high bootstrap current fraction, absolute magnetic well and high pressure driven sheared flow. In addition, the NSTX programme plans to explore fully non-inductive plasma startup as well as a dispersive scrape-off layer for heat and particle flux handling.

Predicting Child Physical Activity and Screen Time: Parental Support for Physical Activity and General Parenting Styles

PubMed Central

Crain, A. Lauren; Senso, Meghan M.; Levy, Rona L.; Sherwood, Nancy E.

2014-01-01

Objective: To examine relationships between parenting styles and practices and child moderate-to-vigorous physical activity (MVPA) and screen time. Methods: Participants were children (6.9 ± 1.8 years) with a body mass index in the 70–95th percentile and their parents (421 dyads). Parent-completed questionnaires assessed parental support for child physical activity (PA), parenting styles and child screen time. Children wore accelerometers to assess MVPA. Results: Parenting style did not predict MVPA, but support for PA did (positive association). The association between support and MVPA, moreover, varied as a function of permissive parenting. For parents high in permissiveness, the association was positive (greater support was related to greater MVPA and therefore protective). For parents low in permissiveness, the association was neutral; support did not matter. Authoritarian and permissive parenting styles were both associated with greater screen time. Conclusions: Parenting practices and styles should be considered jointly, offering implications for tailored interventions. PMID:24812256

Disgust, but not anger provocation, enhances levator labii superioris activity during exposure to moral transgressions.

PubMed

Whitton, Alexis E; Henry, Julie D; Rendell, Peter G; Grisham, Jessica R

2014-02-01

Physical disgust is elicited by, and amplifies responses to, moral transgressions, suggesting that moral disgust may be a biologically expanded form of physical disgust. However, there is limited research comparing the effects of physical disgust to that of other emotions like anger, making it difficult to determine if the link between disgust and morality is unique. The current research evaluated the specificity of the relationship between disgust and morality by comparing links with anger, using state, physiological and trait measures of emotionality. Participants (N=90) were randomly allocated to have disgust, anger or no emotion induced. Responses to images depicting moral, negative non-moral, and neutral themes were then recorded using facial electromyography. Inducing disgust, but not anger, increased psychophysiological responses to moral themes. Trait disgust, but not trait anger, correlated with levator labii responses to moral themes. These findings provide strong evidence of a unique link between physical disgust and morality. Copyright © 2013 Elsevier B.V. All rights reserved.

Examination of the steps leading up to the physical developer process for developing fingerprints.

PubMed

Wilson, Jeffrey Daniel; Cantu, Antonio A; Antonopoulos, George; Surrency, Marc J

2007-03-01

This is a systematic study that examines several acid prewashes and water rinses on paper bearing latent prints before its treatment with a silver physical developer. Specimens or items processed with this method are usually pretreated with an acid wash to neutralize calcium carbonate from the paper before the treatment with a physical developer. Two different acids at varying concentrations were tested on fingerprints. Many different types of paper were examined in order to determine which acid prewash was the most beneficial. Various wash times as well as the addition of a water rinse step before the development were also examined. A pH study was included that monitored the acidity of the solution during the wash step. Scanning electron microscopy was used to verify surface calcium levels for the paper samples throughout the experiment. Malic acid at a concentration of 2.5% proved to be an ideal acid for most papers, providing good fingerprint development with minimal background development. Water rinses were deemed unnecessary before physical development.

Detailed study of spontaneous rotation generation in diverted H-mode plasma using the full-f gyrokinetic code XGC1

NASA Astrophysics Data System (ADS)

Seo, Janghoon; Chang, C. S.; Ku, S.; Kwon, J. M.; Yoon, E. S.

2013-10-01

The Full-f gyrokinetic code XGC1 is used to study the details of toroidal momentum generation in H-mode plasma. Diverted DIII-D geometry is used, with Monte Carlo neutral particles that are recycled at the limiter wall. Nonlinear Coulomb collisions conserve particle, momentum, and energy. Gyrokinetic ions and adiabatic electrons are used in the present simulation to include the effects from ion gyrokinetic turbulence and neoclassical physics, under self-consistent radial electric field generation. Ion orbit loss physics is automatically included. Simulations show a strong co-Ip flow in the H-mode layer at outside midplane, similarly to the experimental observation from DIII-D and ASDEX-U. The co-Ip flow in the edge propagates inward into core. It is found that the strong co-Ip flow generation is mostly from neoclassical physics. On the other hand, the inward momentum transport is from turbulence physics, consistently with the theory of residual stress from symmetry breaking. Therefore, interaction between the neoclassical and turbulence physics is a key factor in the spontaneous momentum generation.

Evolution of Field-Aligned Electron and Ion Densities From Whistler Mode Radio Soundings During Quiet to Moderately Active Period and Comparisons With SAMI2 Simulations

NASA Astrophysics Data System (ADS)

Reddy, A.; Sonwalkar, V. S.; Huba, J. D.

2018-02-01

Knowledge of field-aligned electron and ion distributions is necessary for understanding the physical processes causing variations in field-aligned electron and ion densities. Using whistler mode sounding by Radio Plasma Imager/Imager for Magnetopause-to-Aurora Global Exploration (RPI/IMAGE), we determined the evolution of dayside electron and ion densities along L ˜ 2 and L ˜ 3 (90-4,000 km) during a 7 day (21-27 November 2005) geomagnetically quiet to moderately active period. Over this period the O+/H+ transition height was ˜880 ± 60 km and ˜1000 ± 100 km, respectively, at L ˜ 2 and L ˜ 3. The electron density varied in a complex manner; it was different at L ˜ 2 and L ˜ 3 and below and above the O+/H+ transition height. The measured electron and ion densities are consistent with those from Challenging Minisatellite Payload (CHAMP) and Defense Meteorological Satellite Program (DMSP) and other past measurements, but they deviated from bottomside sounding and International Reference Ionosphere (IRI) 2012 empirical model results. Using SAMI2 (Naval Research Laboratory (NRL) ionosphere model) with reasonably adjusted values of inputs (neutral densities, winds, electric fields, and photoelectron heating), we simulated the evolution of O+/H+ transition height and field-aligned electron and ion densities so that a fair agreement was obtained between the simulation results and observations. Simulation studies indicated that reduced neutral densities (H and/or O) with time limited O+-H charge exchange process. This reduction in neutral densities combined with changes in neutral winds and plasma temperature led to the observed variations in the electron and ion densities. The observation/simulation method presented here can be extended to investigate the role of neutral densities and composition, disturbed winds, and prompt penetration electric fields in the storm time ionosphere/plasmasphere dynamics.

Understanding Plasmas with a High Degree of Correlation Through Modeling: From Rydberg and Fermionic Plasmas to Penning Plasmas

NASA Astrophysics Data System (ADS)

Christlieb, Andrew

2015-09-01

Ultra cold neutral plasmas have gained attention over the past 15 years as being a unique environment for studying moderately to strongly coupled neutral systems. The first ultra cold neutral plasmas were generated by ionizing a Bose Einstein condensate, generating a plasma with .1K ions and 2-4K electrons. These neutral plasmas have the unique property that the ratio of their potential energy to their kinetic energy, (Γ = PE / KE), can greatly exceed 1, leading to a strongly correlated system. The high degree of correlation means that everything from wave propagation through collision dynamics behaves quite differently from their counterpart in traditional neutral plasmas. Currently, a range of gases and different methods for cooling have been used to generate these plasmas from supersonic expansion, through penning trap configurations (reference Tom, Jake and Ed). These systems have time scales form picoseconds to milliseconds have a particle numbers from 105 to 109. These systems present a unique environment for studying the physics of correlation due to their low particle number and small size. We start by reviewing ultra cold plasmas and the current sate of the art in generating these correlated systems. Then we introduce the methods we will use for exploring these systems through direct simulation of Molecular Dynamics models; Momentum Dependent Potentials, Treecodes and Particle-Particle Particle-Mesh methods. We use these tools to look at two key areas of ultra cold plasmas; development of methods to generate a plasma with a Γ >> 1 and the impact of correlation of collisional relaxation. Our eventual goal is to use what we learn to develop models that can simulate correlation in large plasma systems that are outside of the scope of Molecular Dynamics models. In collaboration with Gautham Dharmuman, Mayur Jain, Michael Murillo and John Verboncoeur. This work it supposed by Air Force Office of Scientific Research.

A solenoidal synthetic field and the non-Abelian Aharonov-Bohm effects in neutral atoms

PubMed Central

Huo, Ming-Xia; Nie, Wei; Hutchinson, David A. W.; Kwek, Leong Chuan

2014-01-01

Cold neutral atoms provide a versatile and controllable platform for emulating various quantum systems. Despite efforts to develop artificial gauge fields in these systems, realizing a unique ideal-solenoid-shaped magnetic field within the quantum domain in any real-world physical system remains elusive. Here we propose a scheme to generate a “hairline” solenoid with an extremely small size around 1 micrometer which is smaller than the typical coherence length in cold atoms. Correspondingly, interference effects will play a role in transport. Despite the small size, the magnetic flux imposed on the atoms is very large thanks to the very strong field generated inside the solenoid. By arranging different sets of Laguerre-Gauss (LG) lasers, the generation of Abelian and non-Abelian SU(2) lattice gauge fields is proposed for neutral atoms in ring- and square-shaped optical lattices. As an application, interference patterns of the magnetic type-I Aharonov-Bohm (AB) effect are obtained by evolving atoms along a circle over several tens of lattice cells. During the evolution, the quantum coherence is maintained and the atoms are exposed to a large magnetic flux. The scheme requires only standard optical access, and is robust to weak particle interactions. PMID:25103877

Short Intense Ion Pulses for Materials and Warm Dense Matter Research

NASA Astrophysics Data System (ADS)

Seidl, Peter; Ji, Q.; Lidia, S. M.; Persaud, A.; Stettler, M.; Takakuwa, J. H.; Waldron, W. L.; Schenkel, T.; Barnard, J. J.; Friedman, A.; Grote, D. P.; Davidson, R. C.; Gilson, E. P.; Kaganovich, I. D.

2015-11-01

We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r <1 mm within 2 ns FWHM and approximately 1010 ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li + ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. We will describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminium perovskite using the fully integrated accelerator and neutralized drift compression components (arXiv:1506.05839). This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Correlation between solar flare productivity and photospheric vector magnetic fields

NASA Astrophysics Data System (ADS)

Cui, Yanmei; Wang, Huaning

2008-11-01

Studying the statistical correlation between the solar flare productivity and photospheric magnetic fields is very important and necessary. It is helpful to set up a practical flare forecast model based on magnetic properties and improve the physical understanding of solar flare eruptions. In the previous study ([Cui, Y.M., Li, R., Zhang, L.Y., He, Y.L., Wang, H.N. Correlation between solar flare productivity and photospheric magnetic field properties 1. Maximum horizontal gradient, length of neutral line, number of singular points. Sol. Phys. 237, 45 59, 2006]; from now on we refer to this paper as ‘Paper I’), three measures of the maximum horizontal gradient, the length of the neutral line, and the number of singular points are computed from 23990 SOHO/MDI longitudinal magnetograms. The statistical relationship between the solar flare productivity and these three measures is well fitted with sigmoid functions. In the current work, the three measures of the length of strong-shear neutral line, total unsigned current, and total unsigned current helicity are computed from 1353 vector magnetograms observed at Huairou Solar Observing Station. The relationship between the solar flare productivity and the current three measures can also be well fitted with sigmoid functions. These results are expected to be beneficial to future operational flare forecasting models.

Optimal satellite sampling to resolve global-scale dynamics in the I-T system

NASA Astrophysics Data System (ADS)

Rowland, D. E.; Zesta, E.; Connor, H. K.; Pfaff, R. F., Jr.

2016-12-01

The recent Decadal Survey highlighted the need for multipoint measurements of ion-neutral coupling processes to study the pathways by which solar wind energy drives dynamics in the I-T system. The emphasis in the Decadal Survey is on global-scale dynamics and processes, and in particular, mission concepts making use of multiple identical spacecraft in low earth orbit were considered for the GDC and DYNAMIC missions. This presentation will provide quantitative assessments of the optimal spacecraft sampling needed to significantly advance our knowledge of I-T dynamics on the global scale.We will examine storm time and quiet time conditions as simulated by global circulation models, and determine how well various candidate satellite constellations and satellite schemes can quantify the plasma and neutral convection patterns and global-scale distributions of plasma density, neutral density, and composition, and their response to changes in the IMF. While the global circulation models are data-starved, and do not contain all the physics that we might expect to observe with a global-scale constellation mission, they are nonetheless an excellent "starting point" for discussions of the implementation of such a mission. The result will be of great utility for the design of future missions, such as GDC, to study the global-scale dynamics of the I-T system.

A simulation study of the equatorial ionospheric response to the October 2013 geomagnetic storm

NASA Astrophysics Data System (ADS)

Lei, J.; Ren, D.

2017-12-01

The ionospheric observation from ionosonde at Sao Luis (2.5S, 44.2W; 7S dip latitude) around the magnetic equator showed that the nighttime ionospheric F2 peak height (hmF2) was uplifted by more than 150 km during the October 2013 geomagnetic storm. The changes of hmF2 at the magnetic equator were generally attributed to the variations of vertical drift associated with zonal electric field. In this paper, the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) simulation results are utilized to explore the possible physical mechanisms responsible for the observed increase of hmF2 at Sao Luis. The TIEGCM reproduced the changes of F2 peak electron density (NmF2) and its height (hmF2) during the main and recovery phases of the October 2013 storm. A series of controlled simulations revealed that, besides the enhancement of vertical plasma drift, the convergence of horizontal neutral winds and thermospheric expansion also contributed significantly to the profound increase of nighttime hmF2 observed at Sao Luis on 2 October. Moreover, the changes of neutral winds and neutral temperature in the equatorial region are associated with the interference of storm time travelling atmospheric disturbances originating from high latitudes.

A time-dependent anisotropic plasma chemistry model of the Io plasma torus

NASA Astrophysics Data System (ADS)

Arridge, C. S.

2016-12-01

The physics of the Io plasma torus is typically modelled using one box neutral-plasma chemistry models, often referred to as neutral cloud theory models (e.g., Barbosa 1994; Delamere and Bagenal 2003). These models incorporate electron impact and photoionisation, charge exchange, molecular dissociation/recombination reactions, atomic radiatiative losses and Coulomb collisional heating. Isotropic Maxwellian distributions are usually assumed in the implementation of these models. Observationally a population of suprathermal electrons has been identified in the plasma torus and theoretically they have been shown to be important in reproducing the observed ionisation balance in the torus (e.g., Barbosa 1994). In this paper we describe an anisotropic plasma chemistry model for the Io torus that is inspired by ion cyclotron wave observations (Huddleston et al. 1994; Leisner et al. 2011), ion anisotropies due to pick up (Wilson et al. 2008), and theoretical ideas on the maintenance of the suprathermal electron population (Barbosa 1994). We present both steady state calculations and also time varying solutions (e.g., Delamere et al. 2004) where increases in the neutral source rate in the torus generates perturbations in ion anisotropies that subsequently decay over a timescale much longer than the duration of the initial perturbation. We also present a method for incorporating uncertainties in reaction rates into the model.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedman, A; Kwan, J

Earlier this year, the U.S. Department of Energy Office of Fusion Energy Sciences approved the NDCX-II project, a second-generation Neutralized Drift Compression eXperiment. NDCX-II is a collaborative effort of scientists and engineers from Lawrence Berkeley National Laboratory (LBNL), Lawrence Livermore National Laboratory (LLNL), and the Princeton Plasma Physics Laboratory (PPPL), in a formal collaboration known as the Virtual National Laboratory for Heavy Ion Fusion Science (HIFS-VNL). Supported by $11 M of funding from the American Recovery and Reinvestment Act, construction at LBNL commenced in July of 2009, with completion anticipated in March of 2012. Applications of this facility will includemore » studies of: the basic physics of the poorly understood 'warm dense matter' regime of temperatures around 1 eV and densities near solid, using uniform, volumetric ion heating of thin foil targets; ion energy coupling into an ablating plasma (such as that which occurs in an inertial fusion target) using beams with time-varying kinetic energy; space-charge-dominated ion beam dynamics; and beam focusing and pulse compression in neutralizing plasma. The machine will complement facilities at GSI in Darmstadt, Germany, but will employ lower ion kinetic energies and commensurately shorter stopping ranges in matter. Much of this research will contribute directly toward the collaboration's ultimate goal of electric power production via heavy-ion beam-driven inertial confinement fusion ('Heavy-Ion Fusion', or HIF). In inertial fusion, a target containing fusion fuel is heated by energetic 'driver' beams, and undergoes a miniature thermonuclear explosion. Currently the largest U.S. research program in inertial confinement is at Livermore's National Ignition Facility (NIF), a multibillion-dollar, stadium-sized laser facility optimized for studying physics issues relevant to nuclear stockpile stewardship. Nonetheless, NIF is expected to establish the fundamental feasibility of fusion ignition on the laboratory scale, and thus advance this approach to fusion energy. Heavy ion accelerators have a number of attributes (such as efficiency, longevity, and use of magnetic fields for final focusing) that make them attractive candidates as Inertial Fusion energy (IFE) drivers As with LBNL's existing NDCX-I, the new machine will produce short ion pulses using the technique of neutralized drift compression. A head-to-tail velocity gradient is imparted to the beam, which then shortens as it drifts in neutralizing plasma that suppresses space-charge forces. NDCX-II will make extensive use of induction cells and other hardware from the decommissioned ATA facility at LLNL. Figure (1) shows the layout of the facility, to be sited in LBNL's Building 58 alongside the existing NDCX-I apparatus. This second-generation facility represents a significant upgrade from the existing NDCX-I. It will be extensible and reconfigurable; in the configuration that has received the most emphasis, each NDCX-II pulse will deliver 30 nC of ions at 3 MeV into a mm-scale spot onto a thin-foil target. Pulse compression to {approx} 1 ns occurs in the accelerator as well as in the drift compression line; the beam is manipulated using suitably tailored voltage waveforms in the accelerating gaps. NDCX-II employs novel beam dynamics. To use the 200 kV Blumlein power supplies from ATA (blue cylinders in the figure), the pulse duration must first be reduced to less than 70 ns. This shortening is accomplished in an initial stage of non-neutral drift compression, downstream of the injector and the first few induction cells. The compression is sufficiently rapid that fewer than ten long-pulse waveform generators are needed, with Blumleins powering the rest of the acceleration. Extensive simulation studies have enabled an attractive physics design; these employ both a new 1-D code (ASP) and the VNL's workhorse 2-D/3-D code Warp. Snapshots from a simulation movie (available online) appear in Fig. 2. Studies on a dedicated test stand are quantifying the performance of the ATA hardware and of pulsed solenoids that will provide transverse beam confinement (ions require much stronger fields than the electrons accelerated by ATA). For more information, see the recent article in the Berkeley Lab News and references therein. Joe Kwan is the NDCX-II project manager and Alex Friedman is the leader for the physics design.« less

Physics and engineering design of the accelerator and electron dump for SPIDER

NASA Astrophysics Data System (ADS)

Agostinetti, P.; Antoni, V.; Cavenago, M.; Chitarin, G.; Marconato, N.; Marcuzzi, D.; Pilan, N.; Serianni, G.; Sonato, P.; Veltri, P.; Zaccaria, P.

2011-06-01

The ITER Neutral Beam Test Facility (PRIMA) is planned to be built at Consorzio RFX (Padova, Italy). PRIMA includes two experimental devices: a full size ion source with low voltage extraction called SPIDER and a full size neutral beam injector at full beam power called MITICA. SPIDER is the first experimental device to be built and operated, aiming at testing the extraction of a negative ion beam (made of H- and in a later stage D- ions) from an ITER size ion source. The main requirements of this experiment are a H-/D- extracted current density larger than 355/285 A m-2, an energy of 100 keV and a pulse duration of up to 3600 s. Several analytical and numerical codes have been used for the design optimization process, some of which are commercial codes, while some others were developed ad hoc. The codes are used to simulate the electrical fields (SLACCAD, BYPO, OPERA), the magnetic fields (OPERA, ANSYS, COMSOL, PERMAG), the beam aiming (OPERA, IRES), the pressure inside the accelerator (CONDUCT, STRIP), the stripping reactions and transmitted/dumped power (EAMCC), the operating temperature, stress and deformations (ALIGN, ANSYS) and the heat loads on the electron dump (ED) (EDAC, BACKSCAT). An integrated approach, taking into consideration at the same time physics and engineering aspects, has been adopted all along the design process. Particular care has been taken in investigating the many interactions between physics and engineering aspects of the experiment. According to the 'robust design' philosophy, a comprehensive set of sensitivity analyses was performed, in order to investigate the influence of the design choices on the most relevant operating parameters. The design of the SPIDER accelerator, here described, has been developed in order to satisfy with reasonable margin all the requirements given by ITER, from the physics and engineering points of view. In particular, a new approach to the compensation of unwanted beam deflections inside the accelerator and a new concept for the ED have been introduced.

Open Questions, New Instrumentation, and Challenges for Heliospheric Physics beyond 2020

NASA Astrophysics Data System (ADS)

Desai, Mihir; Allegrini, Frederic

The last decade has seen tremendous breakthroughs in our knowledge of the outer edges of the heliosphere and the interaction between the Sun and its local galactic neighborhood. These advances include the crossing of the termination shock and perhaps the heliopause by Voyager 1 and global imaging of energetic neutral atom (ENA) emission from the outer heliosphere by IBEX and Cassini. IBEX discovered a narrow “ribbon” of ENA emissions encircling the heliosphere, and provided direct measurements of interstellar neutral atoms that point to the absence of a bow shock beyond the heliopause. The big picture provided by IBEX, complemented by Voyager observations, shows that the asymmetry of the heliosphere is shaped by the surrounding interstellar magnetic field and that the physical processes that control the interaction exist on relatively small spatial and temporal scales (months) that are not currently measured. Additionally, in-situ observations from ACE, Wind, SoHO, SAMPEX, and STEREO have contributed dramatically to our understanding of solar energetic particle (SEP) events, of the importance of suprathermal ions for efficient energization, of the sources and evolution of solar wind, interplanetary magnetic field, corona mass ejections (CMEs), and SEPs that impact geospace and the heliosphere. These phenomena are controlled by myriad complex and poorly understood physical effects that must be unraveled to develop a complete picture of particle acceleration and transport and of the causes and impacts of interplanetary disturbances on geospace and the heliosphere. In this talk I will summarize our current state of knowledge in heliospheric physics, identify key questions that will be addressed by upcoming missions like Solar Probe Plus and Solar Orbiter, and then discuss a new set of challenges that need to be met in order to obtain a complete understanding of the solar and interplanetary drivers of Space Weather and SEPs, and to discover how our heliosphere interacts with the nearby interstellar and galactic environments.

A Massively Parallel Hybrid Dusty-Gasdynamics and Kinetic Direct Simulation Monte Carlo Model for Planetary Applications

NASA Technical Reports Server (NTRS)

Combi, Michael R.

2004-01-01

In order to understand the global structure, dynamics, and physical and chemical processes occurring in the upper atmospheres, exospheres, and ionospheres of the Earth, the other planets, comets and planetary satellites and their interactions with their outer particles and fields environs, it is often necessary to address the fundamentally non-equilibrium aspects of the physical environment. These are regions where complex chemistry, energetics, and electromagnetic field influences are important. Traditional approaches are based largely on hydrodynamic or magnetohydrodynamic (MHD) formulations and are very important and highly useful. However, these methods often have limitations in rarefied physical regimes where the molecular collision rates and ion gyrofrequencies are small and where interactions with ionospheres and upper neutral atmospheres are important. At the University of Michigan we have an established base of experience and expertise in numerical simulations based on particle codes which address these physical regimes. The Principal Investigator, Dr. Michael Combi, has over 20 years of experience in the development of particle-kinetic and hybrid kinetichydrodynamics models and their direct use in data analysis. He has also worked in ground-based and space-based remote observational work and on spacecraft instrument teams. His research has involved studies of cometary atmospheres and ionospheres and their interaction with the solar wind, the neutral gas clouds escaping from Jupiter s moon Io, the interaction of the atmospheres/ionospheres of Io and Europa with Jupiter s corotating magnetosphere, as well as Earth s ionosphere. This report describes our progress during the year. The contained in section 2 of this report will serve as the basis of a paper describing the method and its application to the cometary coma that will be continued under a research and analysis grant that supports various applications of theoretical comet models to understanding the inner comae of comets (grant NAGS- 13239 from the Planetary Atmospheres program).

How We Know It Hurts: Item Analysis of Written Narratives Reveals Distinct Neural Responses to Others' Physical Pain and Emotional Suffering

PubMed Central

Bruneau, Emile; Dufour, Nicholas; Saxe, Rebecca

2013-01-01

People are often called upon to witness, and to empathize with, the pain and suffering of others. In the current study, we directly compared neural responses to others' physical pain and emotional suffering by presenting participants (n = 41) with 96 verbal stories, each describing a protagonist's physical and/or emotional experience, ranging from neutral to extremely negative. A separate group of participants rated “how much physical pain”, and “how much emotional suffering” the protagonist experienced in each story, as well as how “vivid and movie-like” the story was. Although ratings of Pain, Suffering and Vividness were positively correlated with each other across stories, item-analyses revealed that each scale was correlated with activity in distinct brain regions. Even within regions of the “Shared Pain network” identified using a separate data set, responses to others' physical pain and emotional suffering were distinct. More broadly, item analyses with continuous predictors provided a high-powered method for identifying brain regions associated with specific aspects of complex stimuli – like verbal descriptions of physical and emotional events. PMID:23638181

See your friends close and your enemies closer: social identity and identity threat shape the representation of physical distance.

PubMed

Xiao, Y Jenny; Van Bavel, Jay J

2012-07-01

Three studies demonstrated that collective identity and identity threat shape representations of the physical world. In Study 1, New York Yankees fans estimated Fenway Park, the stadium of a threatening out-group (but not Camden Yards, the stadium of a neutral out-group) to be closer than did non-Yankees fans. In Study 2, the authors manipulated identity threat among people affiliated (or not) with New York University (NYU). When Columbia University was portrayed as threatening to NYU, NYU affiliates estimated Columbia as closer than did non-affiliates, compared with when Columbia was nonthreatening. In Study 3, Americans who perceived more symbolic threats from Mexican immigration estimated Mexico City as closer. Collective identification with the in-group moderated effects of threat on distance estimations. These studies suggest that social categorization, collective identification, and identity threat work in concert to shape the representations of the physical world.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwok, A.G.

This paper examines the comfort criteria of ANSI/ASHRAE Standard 55-1992 for their applicability in tropical classrooms. A field study conducted in Hawaii used a variety of methods to collect the data: survey questionnaires, physical measurements, interviews, and behavioral observations. A total of 3,544 students and teachers completed questionnaires in 29 naturally ventilated and air-conditioned classrooms in six schools during two seasons. The majority of classrooms failed to meet the physical specifications of the Standard 55 comfort zone. Thermal neutrality, preference, and acceptability results are compared with other field studies and the Standard 55 criteria. Acceptability votes by occupants of bothmore » naturally ventilated and air-conditioned classrooms exceeded the standard`s 80% acceptability criteria, regardless of whether physical conditions were in or out of the comfort zone. Responses from these two school populations suggest not only a basis for separate comfort standards but energy conservation opportunities through raising thermostat set points.« less

Fusion energy division annual progress report, period ending December 31, 1980

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1981-11-01

The ORNL Program encompasses most aspects of magnetic fusion research including research on two magnetic confinement programs (tokamaks and ELMO bumpy tori); the development of the essential technologies for plasma heating, fueling, superconducting magnets, and materials; the development of diagnostics; the development of atomic physics and radiation effect data bases; the assessment of the environmental impact of magnetic fusion; the physics and engineering of present-generation devices; and the design of future devices. The integration of all of these activities into one program is a major factor in the success of each activity. An excellent example of this integration is themore » extremely successful application of neutral injection heating systems developed at ORNL to tokamaks both in the Fusion Energy Division and at Princeton Plasma Physics Laboratory (PPPL). The goal of the ORNL Fusion Program is to maintain this balance between plasma confinement, technology, and engineering activities.« less

MPD Thruster Performance Analytic Models

NASA Technical Reports Server (NTRS)

Gilland, James; Johnston, Geoffrey

2003-01-01

Magnetoplasmadynamic (MPD) thrusters are capable of accelerating quasi-neutral plasmas to high exhaust velocities using Megawatts (MW) of electric power. These characteristics make such devices worthy of consideration for demanding, far-term missions such as the human exploration of Mars or beyond. Assessment of MPD thrusters at the system and mission level is often difficult due to their status as ongoing experimental research topics rather than developed thrusters. However, in order to assess MPD thrusters utility in later missions, some adequate characterization of performance, or more exactly, projected performance, and system level definition are required for use in analyses. The most recent physical models of self-field MPD thrusters have been examined, assessed, and reconfigured for use by systems and mission analysts. The physical models allow for rational projections of thruster performance based on physical parameters that can be measured in the laboratory. The models and their implications for the design of future MPD thrusters are presented.

MPD Thruster Performance Analytic Models

NASA Technical Reports Server (NTRS)

Gilland, James; Johnston, Geoffrey

2007-01-01

Magnetoplasmadynamic (MPD) thrusters are capable of accelerating quasi-neutral plasmas to high exhaust velocities using Megawatts (MW) of electric power. These characteristics make such devices worthy of consideration for demanding, far-term missions such as the human exploration of Mars or beyond. Assessment of MPD thrusters at the system and mission level is often difficult due to their status as ongoing experimental research topics rather than developed thrusters. However, in order to assess MPD thrusters utility in later missions, some adequate characterization of performance, or more exactly, projected performance, and system level definition are required for use in analyses. The most recent physical models of self-field MPD thrusters have been examined, assessed, and reconfigured for use by systems and mission analysts. The physical models allow for rational projections of thruster performance based on physical parameters that can be measured in the laboratory. The models and their implications for the design of future MPD thrusters are presented.

Physical Model for the Evolution of the Genetic Code

NASA Astrophysics Data System (ADS)

Yamashita, Tatsuro; Narikiyo, Osamu

2011-12-01

Using the shape space of codons and tRNAs we give a physical description of the genetic code evolution on the basis of the codon capture and ambiguous intermediate scenarios in a consistent manner. In the lowest dimensional version of our description, a physical quantity, codon level is introduced. In terms of the codon levels two scenarios are typically classified into two different routes of the evolutional process. In the case of the ambiguous intermediate scenario we perform an evolutional simulation implemented cost selection of amino acids and confirm a rapid transition of the code change. Such rapidness reduces uncomfortableness of the non-unique translation of the code at intermediate state that is the weakness of the scenario. In the case of the codon capture scenario the survival against mutations under the mutational pressure minimizing GC content in genomes is simulated and it is demonstrated that cells which experience only neutral mutations survive.

The role of partial ionization effects in the chromosphere

PubMed Central

Martínez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo; Carlsson, Mats

2015-01-01

The energy for the coronal heating must be provided from the convection zone. However, the amount and the method by which this energy is transferred into the corona depend on the properties of the lower atmosphere and the corona itself. We review: (i) how the energy could be built in the lower solar atmosphere, (ii) how this energy is transferred through the solar atmosphere, and (iii) how the energy is finally dissipated in the chromosphere and/or corona. Any mechanism of energy transport has to deal with the various physical processes in the lower atmosphere. We will focus on a physical process that seems to be highly important in the chromosphere and not deeply studied until recently: the ion–neutral interaction effects in the chromosphere. We review the relevance and the role of the partial ionization in the chromosphere and show that this process actually impacts considerably the outer solar atmosphere. We include analysis of our 2.5D radiative magnetohydrodynamic simulations with the Bifrost code (Gudiksen et al. 2011 Astron. Astrophys. 531, A154 (doi:10.1051/0004-6361/201116520)) including the partial ionization effects on the chromosphere and corona and thermal conduction along magnetic field lines. The photosphere, chromosphere and transition region are partially ionized and the interaction between ionized particles and neutral particles has important consequences on the magneto-thermodynamics of these layers. The partial ionization effects are treated using generalized Ohm's law, i.e. we consider the Hall term and the ambipolar diffusion (Pedersen dissipation) in the induction equation. The interaction between the different species affects the modelled atmosphere as follows: (i) the ambipolar diffusion dissipates magnetic energy and increases the minimum temperature in the chromosphere and (ii) the upper chromosphere may get heated and expanded over a greater range of heights. These processes reveal appreciable differences between the modelled atmospheres of simulations with and without ion–neutral interaction effects. PMID:25897096

The Nox1/4 dual inhibitor GKT137831 or Nox4 knockdown inhibits Angiotensin-II-induced adult mouse cardiac fibroblast proliferation and migration. AT1 physically associates with Nox4

PubMed Central

Somanna, Naveen K.; Valente, Anthony J.; Krenz, Maike; Fay, William P.; Delafontaine, Patrice; Chandrasekar, Bysani

2017-01-01

Both oxidative stress and inflammation contribute to chronic hypertension-induced myocardial fibrosis and adverse cardiac remodeling. Here we investigated whether angiotensin (Ang)-II-induced fibroblast proliferation and migration are NADPH oxidase (Nox) 4/ROS and IL-18 dependent. Our results show that the potent induction of mouse cardiac fibroblast (CF) proliferation and migration by Ang-II is markedly attenuated by Nox4 knockdown and the Nox inhibitor DPI. Further, Nox4 knockdown and DPI pre-treatment attenuate Ang-II-induced IL-18, IL-18Rα and collagen expression, and MMP9 activation. While neutralization of IL-18 blunted Ang-II-induced CF proliferation and migration, knockdown of MMP9 attenuated CF migration. The antioxidant NAC and the cell-permeable SOD mimetics Tempol, MnTBAP, and MnTMPyP attenuated oxidative stress and inhibit CF proliferation and migration. The Nox1/Nox4 dual inhibitor GKT137831 also blunted Ang-II-induced H2O2 production and CF proliferation and migration. Further, AT1 binds Nox4, and Ang-II enhanced their physical association. Notably, GKT137831 attnuated the AT1/Nox4 interaction. These results indicate that Ang-II induces CF proliferation and migration in part via Nox4/ROS-dependent IL-18 induction and MMP9 activation, and may involve AT1/Nox4 physical association. Thus, either (i) neutralizing IL-18, (ii) blocking AT1/Nox4 interaction or (iii) use of the Nox1/Nox4 inhibitor GKT137831 may have therapeutic potential in chronic hypertension-induced adverse cardiac remodeling. PMID:26445208

New concepts for molecular magnets

NASA Astrophysics Data System (ADS)

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-paramagnetism and quasi one-dimensional magnets.

The MØLLER experiment at Jefferson Lab: search for physics beyond the Standard Model

NASA Astrophysics Data System (ADS)

van Oers, Willem T. H.

2010-07-01

The MO/LLER experiment at Jefferson Lab will measure the parity-violating analyzing power Az in the scattering of 11 GeV longitudinally polarized electrons from the atomic electrons in a liquid hydrogen target (Mo/ller scattering). In the Standard Model a non-zero Az is due to the interference of the electromagnetic amplitude and the weak neutral current amplitude, the latter mediated by the Z0 boson. Az is predicted to be 35.6 parts per billion (ppb) at the kinematics of the experiment. It is the objective of the experiment to measure Az to a precision of 0.73 ppb. This result would yield a measurement of the weak charge of the electron QWe to a fractional error of 2.3% at an average value Q2 of 0.0056 (GeV/c)2. This in turn will yield a determination of the weak mixing angle sin2θw with an uncertainty of ±0.00026(stat) ±0.00013(syst), comparable to the accuracy of the two best determinations at high energy colliders (at the Z0 pole). Consequently, the result could potentially influence the central value of this fundamental electroweak parameter, which is of critical importance in deciphering any signal of new physics that might be observed at the Large Hadron Collider (LHC). The measurement is sensitive to the interference of the electromagnetic amplitude with new neutral current amplitudes as weak as 10-3 GF from as yet unknown high energy dynamics, a level of sensitivity unlikely to be matched in any experiment measuring a flavor and CP conserving process in the next decade. This provides indirect access to new physics at multi-TeV scales in a manner complementary to direct searches at the LHC.

Effects of perceptual and conceptual similarity in lexical priming of young children who stutter: preliminary findings.

PubMed

Hartfield, Kia N; Conture, Edward G

2006-01-01

The purpose of this study was to investigate the influence of conceptual and perceptual properties of words on the speed and accuracy of lexical retrieval of children who do (CWS) and do not stutter (CWNS) during a picture-naming task. Participants consisted of 13 3-5-year-old CWS and the same number of CWNS. All participants had speech, language, and hearing development within normal limits, with the exception of stuttering for CWS. Both talker groups participated in a picture-naming task where they named, one at a time, computer-presented, black-on-white drawings of common age-appropriate objects. These pictures were named during four auditory priming conditions: (a) a neutral prime consisting of a tone, (b) a word prime physically related to the target word, (c) a word prime functionally related to the target word, and (d) a word prime categorically related to the target word. Speech reaction time (SRT) was measured from the offset of presentation of the picture target to the onset of participant's verbal speech response. Results indicated that CWS were slower than CWNS across priming conditions (i.e., neutral, physical, function, category) and that the speed of lexical retrieval of CWS was more influenced by functional than perceptual aspects of target pictures named. Findings were taken to suggest that CWS tend to organize lexical information functionally more so than physically and that this tendency may relate to difficulties establishing normally fluent speech and language. The reader will learn about and be able to (1) communicate the relevance of examining lexical retrieval in relation to childhood stuttering and (2) describe the method of measuring speech reaction times of accurate and fluent responses during a picture-naming task as a means of assessing lexical retrieval skills.

Guidelines for Mass Casualty Decontamination During a HAZMAT/Weapon of Mass Destruction Incident. Volumes 1 and 2 (Update)

DTIC Science & Technology

2013-08-01

neutralization: 1. Physical removal involves mechanical action with techniques such as gentle fric- tion (such as rubbing with hands, soft non...sulfur mustard), using gen- tle friction, such as rubbing with hands, a soft cloth, or sponges is recommended to aid in re- moval of the contaminants...account for both initial mass decontamination and secondary de- contamination. Some examples include the use of colored rubber bands and specially de

Ergonomic Worksite Analysis of an Army Dental Clinic

DTIC Science & Technology

1992-08-01

conducted in which duration of hand grip used (power, pinch, retraction, other) and wrist position (ulnar deviation, radial deviation, neutral...DIAGNOSTIC TESTS percent n Nerve Conduction Study 61 11 X-ray of the wrist or hand 38 7 Grip and/or pinch strength 38 7 Dexterity Testing 33 6 Bone Scan 22 4... hand /wrist symptoms. Back and shoulder pain was reported by 53% of the respondents. Psychosocial factors as well as physical risk factors were found to

Lagrangian Coherent Structures in Tropical Cyclone Intensification

DTIC Science & Technology

2011-09-21

the system -scale circulation.20 1For reference, the connection between the moist entropy (s) and θe is s=cp ln(θe), where cp is the specific heat of...of sensible heat, moisture, and momentum between the atmosphere and the ocean . The model calcu- lations were initialized using a convectively neutral...acpd-11-1-2011 © Author(s) 2011. CC Attribution 3.0 License. Atmospheric Chemistry and Physics Discussions This discussion paper is/has been under

A colored KNT neutrino model

DOE PAGES

Nomura, Takaaki; Okada, Hiroshi; Okada, Nobuchika

2016-09-22

Here, we propose a radiative seesaw model at the three-loop level, in which quarks, leptons, leptoquark bosons, and a Majorana fermion of dark matter candidate are involved in the neutrino loop. When analyzing neutrino oscillation data includes all possible constraints such as flavor changing neutral currents, lepton flavor violations, upper/lower bound on the mass of leptoquark from the collider physics, and the measured relic density of the dark matter, we show the allowed region to satisfy all the data/constraints.

GLAST/EAAT1-induced glutamine release via SNAT3 in Bergmann glial cells: evidence of a functional and physical coupling.

PubMed

Martínez-Lozada, Zila; Guillem, Alain M; Flores-Méndez, Marco; Hernández-Kelly, Luisa C; Vela, Carmelita; Meza, Enrique; Zepeda, Rossana C; Caba, Mario; Rodríguez, Angelina; Ortega, Arturo

2013-05-01

Glutamate, the major excitatory transmitter in the vertebrate brain, is removed from the synaptic cleft by a family of sodium-dependent glutamate transporters profusely expressed in glial cells. Once internalized, it is metabolized by glutamine synthetase to glutamine and released to the synaptic space through sodium-dependent neutral amino acid carriers of the N System (SNAT3/slc38a3/SN1, SNAT5/slc38a5/SN2). Glutamine is then taken up by neurons completing the so-called glutamate/glutamine shuttle. Despite of the fact that this coupling was described decades ago, it is only recently that the biochemical framework of this shuttle has begun to be elucidated. Using the established model of cultured cerebellar Bergmann glia cells, we sought to characterize the functional and physical coupling of glutamate uptake and glutamine release. A time-dependent Na⁺-dependent glutamate/aspartate transporter/EAAT1-induced System N-mediated glutamine release could be demonstrated. Furthermore, D-aspartate, a specific glutamate transporter ligand, was capable of enhancing the co-immunoprecipitation of Na⁺-dependent glutamate/aspartate transporter and Na⁺-dependent neutral amino acid transporter 3, whereas glutamine tended to reduce this association. Our results suggest that glial cells surrounding glutamatergic synapses may act as sensors of neuron-derived glutamate through their contribution to the neurotransmitter turnover. © 2013 International Society for Neurochemistry.

Spontaneous collapse: A solution to the measurement problem and a source of the decay in mesonic systems

NASA Astrophysics Data System (ADS)

Simonov, Kyrylo; Hiesmayr, Beatrix C.

2016-11-01

Dynamical reduction models propose a solution to the measurement problem in quantum mechanics: the collapse of the wave function becomes a physical process. We compute the predictions to decaying and flavor-oscillating neutral mesons for the two most promising collapse models, the QMUPL (quantum mechanics with universal position localization) model and the mass-proportional CSL (continuous spontaneous localization) model. Our results are showing (i) a strong sensitivity to the very assumptions of the noise field underlying those two collapse models and (ii) under particular assumptions the CSL case allows one even to recover the decay dynamics. This in turn allows one to predict the effective collapse rates solely based on the measured values for the oscillation (mass differences) and the measured values of the decay constants. The four types of neutral mesons (K meson, D meson, Bd meson, and Bs meson) lead surprisingly to ranges comparable to those put forward by Adler [J. Phys. A: Math. Theor. 40, 2935 (2007), 10.1088/1751-8113/40/12/S03] and Ghirardi, Rimini, and Weber [Phys. Rev. D 34, 470 (1986), 10.1103/PhysRevD.34.470]. Our results show that these systems at high energies are very sensitive to possible modifications of the standard quantum theory, making them a very powerful laboratory to rule out certain collapse scenarios and study the detailed physical processes solving the measurement problem.

Sensitivity of Ionosphere/Thermosphere to different high-latitude drivers

NASA Astrophysics Data System (ADS)

Shim, J.; Kuznetsova, M. M.; Rastaetter, L.; Swindell, M.; Codrescu, M.; Emery, B. A.; Foerster, M.; Foster, B.; Fuller-Rowell, T. J.; Mannucci, A. J.; Pi, X.; Prokhorov, B.; Ridley, A. J.; Coster, A. J.; Goncharenko, L. P.; Lomidze, L.; Scherliess, L.; Crowley, G.

2013-12-01

We compared Ionosphere/Thermosphere (IT) parameters, which were obtained using different models for the high-latitude ionospheric electric potential (e.g., Weimer 2005, AMIE (assimilative mapping of ionospheric electrodynamics) and global magnetosphere models (e.g. Space Weather Modeling Framework)) and particle precipitation (e.g., Fuller-Rowell & Evans, Roble & Ridley, and SWMF). For this study, the physical parameters such as Total Electron Content (TEC), NmF2 and hmF2, and electron and neutral densities at the CHAMP satellite track are considered. In addition, we compared the modeled physical parameters with observed data including ground-based GPS TEC measurements, NmF2 and hmF2 from COSMIC LEO satellites in the selected 5 degree eight longitude sectors, and Ne and neutral density measured by the CHAMP satellite. We quantified the performance of the models using skill scores. Furthermore, the skill scores are obtained for three latitude regions (low, middle and high latitudes) in order to investigate latitudinal dependence of the models' performance. This study is supported by the Community Coordinated Modeling Center (CCMC) at the Goddard Space Flight Center. The CCMC converted ionosphere drivers from a variety of sources and developed an interpolation tool that can be employed by any modelers for easy driver swapping. Model outputs and observational data used for the study will be permanently posted at the CCMC website (http://ccmc.gsfc.nasa.gov) as a resource for the space science communities to use.

Investigation of physical processes limiting plasma density in H-mode on DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maingi, R.; Mahdavi, M.A.; Jernigan, T.C.

1996-12-01

A series of experiments was conducted on the DIII-D tokamak to investigate the physical processes which limit density in high confinement mode (H-mode) discharges. The typical H-mode to low confinement mode (L-mode) transition limit at high density near the empirical Greenwald density limit was avoided by divertor pumping, which reduced divertor neutral pressure and prevented formation of a high density, intense radiation zone (MARFE) near the X-point. It was determined that the density decay time after pellet injection was independent of density relative to the Greenwald limit and increased non-linearly with the plasma current. Magnetohydrodynamic (MHD) activity in pellet-fueled plasmasmore » was observed at all power levels, and often caused unacceptable confinement degradation, except when the neutral beam injected (NBI) power was {le} 3 MW. Formation of MARFEs on closed field lines was avoided with low safety factor (q) operation but was observed at high q, qualitatively consistent with theory. By using pellet fueling and optimizing discharge parameters to avoid each of these limits, an operational space was accessed in which density {approximately} 1.5 {times} Greenwald limit was achieved for 600 ms, and good H-mode confinement was maintained for 300 ms of the density flattop. More significantly, the density was successfully increased to the limit where a central radiative collapse was observed, the most fundamental density limit in tokamaks.« less

COHERENT constraints to conventional and exotic neutrino physics

NASA Astrophysics Data System (ADS)

Papoulias, D. K.; Kosmas, T. S.

2018-02-01

The process of neutral-current coherent elastic neutrino-nucleus scattering, consistent with the Standard Model (SM) expectation, has been recently measured by the COHERENT experiment at the Spallation Neutron Source. On the basis of the observed signal and our nuclear calculations for the relevant Cs and I isotopes, the extracted constraints on both conventional and exotic neutrino physics are updated. The present study concentrates on various SM extensions involving vector and tensor nonstandard interactions as well as neutrino electromagnetic properties, with an emphasis on the neutrino magnetic moment and the neutrino charge radius. Furthermore, models addressing a light sterile neutrino state and scenarios with new propagator fields—such as vector Z' and scalar bosons—are examined, and the corresponding regions excluded by the COHERENT experiment are presented.

Fundamentals of Plasma Physics

NASA Astrophysics Data System (ADS)

Bellan, Paul M.

2008-07-01

Preface; 1. Basic concepts; 2. The Vlasov, two-fluid, and MHD models of plasma dynamics; 3. Motion of a single plasma particle; 4. Elementary plasma waves; 5. Streaming instabilities and the Landau problem; 6. Cold plasma waves in a magnetized plasma; 7. Waves in inhomogeneous plasmas and wave energy relations; 8. Vlasov theory of warm electrostatic waves in a magnetized plasma; 9. MHD equilibria; 10. Stability of static MHD equilibria; 11. Magnetic helicity interpreted and Woltjer-Taylor relaxation; 12. Magnetic reconnection; 13. Fokker-Planck theory of collisions; 14. Wave-particle nonlinearities; 15. Wave-wave nonlinearities; 16. Non-neutral plasmas; 17. Dusty plasmas; Appendix A. Intuitive method for vector calculus identities; Appendix B. Vector calculus in orthogonal curvilinear coordinates; Appendix C. Frequently used physical constants and formulae; Bibliography; References; Index.

Affective signals of threat increase perceived proximity.

PubMed

Cole, Shana; Balcetis, Emily; Dunning, David

2013-01-01

Do stimuli appear to be closer when they are more threatening? We tested people's perceptions of distance to stimuli that they felt were threatening relative to perceptions of stimuli they felt were disgusting or neutral. Two studies demonstrated that stimuli that emitted affective signals of threat (e.g., an aggressive male student) were seen as physically closer than stimuli that emitted affective signals of disgust (e.g., a repulsive male student) or no affective signal. Even after controlling for the direct effects of physiological arousal, object familiarity, and intensity of the negative emotional reaction, we found that threatening stimuli appeared to be physically closer than did disgusting ones (Study 2). These findings highlight the links among biased perception, action regulation, and successful navigation of the environment.

Semileptonic B-meson decays to light pseudoscalar mesons on the HISQ ensembles

NASA Astrophysics Data System (ADS)

Gelzer, Zechariah; Bernard, C.; Tar, C. De; El-Khadra, AX; Gámiz, E.; Gottlieb, Steven; Kronfeld, Andreas S.; Liu, Yuzhi; Meurice, Y.; Simone, J. N.; Toussaint, D.; Water, R. S. Van de; Zhou, R.

2018-03-01

We report the status of an ongoing lattice-QCD calculation of form factors for exclusive semileptonic decays of B mesons with both charged currents (B → πlv, Bs → Klv) and neutral currents (B → πl+l-, B → Kl+l-). The results are important for constraining or revealing physics beyond the Standard Model. This work uses MILC's (2+1 + 1)-flavor ensembles with the HISQ action for the sea and light valence quarks and the clover action in the Fermilab interpretation for the b quark. Simulations are carried out at three lattice spacings down to 0.088 fm, with both physical and unphysical sea-quark masses. We present preliminary results for correlation-function fits.

Parameterized Cross Sections for Pion Production in Proton-Proton Collisions

NASA Technical Reports Server (NTRS)

Blattnig, Steve R.; Swaminathan, Sudha R.; Kruger, Adam T.; Ngom, Moussa; Norbury, John W.; Tripathi, R. K.

2000-01-01

An accurate knowledge of cross sections for pion production in proton-proton collisions finds wide application in particle physics, astrophysics, cosmic ray physics, and space radiation problems, especially in situations where an incident proton is transported through some medium and knowledge of the output particle spectrum is required when given the input spectrum. In these cases, accurate parameterizations of the cross sections are desired. In this paper much of the experimental data are reviewed and compared with a wide variety of different cross section parameterizations. Therefore, parameterizations of neutral and charged pion cross sections are provided that give a very accurate description of the experimental data. Lorentz invariant differential cross sections, spectral distributions, and total cross section parameterizations are presented.

The Environment-Power System Analysis Tool development program. [for spacecraft power supplies

NASA Technical Reports Server (NTRS)

Jongeward, Gary A.; Kuharski, Robert A.; Kennedy, Eric M.; Wilcox, Katherine G.; Stevens, N. John; Putnam, Rand M.; Roche, James C.

1989-01-01

The Environment Power System Analysis Tool (EPSAT) is being developed to provide engineers with the ability to assess the effects of a broad range of environmental interactions on space power systems. A unique user-interface-data-dictionary code architecture oversees a collection of existing and future environmental modeling codes (e.g., neutral density) and physical interaction models (e.g., sheath ionization). The user-interface presents the engineer with tables, graphs, and plots which, under supervision of the data dictionary, are automatically updated in response to parameter change. EPSAT thus provides the engineer with a comprehensive and responsive environmental assessment tool and the scientist with a framework into which new environmental or physical models can be easily incorporated.

Nuclear disarmament verification via resonant phenomena.

PubMed

Hecla, Jake J; Danagoulian, Areg

2018-03-28

Nuclear disarmament treaties are not sufficient in and of themselves to neutralize the existential threat of the nuclear weapons. Technologies are necessary for verifying the authenticity of the nuclear warheads undergoing dismantlement before counting them toward a treaty partner's obligation. Here we present a concept that leverages isotope-specific nuclear resonance phenomena to authenticate a warhead's fissile components by comparing them to a previously authenticated template. All information is encrypted in the physical domain in a manner that amounts to a physical zero-knowledge proof system. Using Monte Carlo simulations, the system is shown to reveal no isotopic or geometric information about the weapon, while readily detecting hoaxing attempts. This nuclear technique can dramatically increase the reach and trustworthiness of future nuclear disarmament treaties.

The WHAM Hα Magellanic Stream Survey: Progress and Early Results

NASA Astrophysics Data System (ADS)

Smart, Brianna; Haffner, L. Matthew; Barger, Kat; Krishnarao, Dhanesh

2017-01-01

We present early analysis of the Hα survey of the Magellanic Stream using the Wisconsin H-Alpha Mapper (WHAM). The neutral component of the Stream extends some 200° across the sky (Nidever et al. 2010). However, the full extent of the ionized gas has not been mapped in detail. Previous studies (e.g., Putman et al. 2003; Weiner & Williams 1996) suggest that ionized gas is likely to be found all along the length of the Stream, and may extend beyond the current neutral boundaries as traced by 21 cm. Barger et al. (2013) used WHAM to map ionized gas throughout the Magellanic Bridge between the Magellanic Clouds. Although ionized emission tracks the neutral emission for the most part, it often spans a few degrees away from the H I at slightly offset velocities. Additionally, Fox et al. (2014) find evidence in an absorption line study that the tidal debris in the Magellanic System contains twice as much ionized gas as neutral material and may extend 30° away from 21-cm sensitivity boundaries. We are now compiling the first comprehensive picture of the ionized component of the Magellanic Stream using WHAM's unprecedented sensitivity to trace diffuse emission (~tens of mR), its velocity resolution (12 km/s) to separate the Stream from the Milky Way, and its multiwavelength capabilities (e.g., [S II] and [N II]) to examine the physical conditions of the gas. Much of the data along the primary axis of the Stream has been collected for the first phase of this extensive study, a complete kinematic Hα survey of the Stream. We present survey progress, challenges in extracting Stream emission, and first-look kinematic maps at select positions along the Stream.

VLA neutral hydrogen imaging of compact groups

NASA Technical Reports Server (NTRS)

Williams, B. A.; Mcmahon, P. M.; Vangorkom, J. H.

1990-01-01

Images of the neutral hydrogen (H I) in the direction of the compact groups of galaxies, HCG 31, HCG 44, and HCG 79 are presented. The authors find in HCG 31 and HCG 79, emission contained within a cloud much larger than the galaxies as well as the entire group. The H I emission associated with HCG 44 is located within the individual galaxies but shows definite signs of tidal interactions. The authors imaged the distribution and kinematics of neutral hydrogen at the two extremes of group sizes represented in Hickson's sample. HCG 44 is at the upper limit while HCG 18, HCG 31, and HCG 79 are at the lower end. Although the number of groups that have been imaged is still very small, there may be a pattern emerging which describes the H I morphology of compact groups. The true nature of compact groups has been the subject of considerable debate and controversy. The most recent observational and theoretical evidence strongly suggests that compact groups are physically dense, dynamical systems that are in the process of merging into a single object (Williams and Rood 1987, Hickson and Rood 1988, Barnes 1989). The neutral hydrogen deficiency observed by Williams and Rood (1987) is consistent with a model in which frequent galactic collisions and interactions have heated some of the gas during the short lifetime of the group. The H I disks which are normally more extended than the luminous ones are expected to be more sensitive to collisions and to trace the galaxy's response to recent interactions. Very Large Array observations can provide in most cases the spatial resolution needed to confirm the dynamical interactions in these systems.

Diverse specificity and effector function among human antibodies to HIV-1 envelope glycoprotein epitopes exposed by CD4 binding

DOE PAGES

Guan, Yongjun; Pazgier, Marzena; Sajadi, Mohammad M.; ...

2012-12-13

The HIV-1 envelope glycoprotein (Env) undergoes conformational transitions consequent to CD4 binding and coreceptor engagement during viral entry. The physical steps in this process are becoming defined, but less is known about their significance as targets of antibodies potentially protective against HIV-1 infection. Here we probe the functional significance of transitional epitope exposure by characterizing 41 human mAbs specific for epitopes exposed on trimeric Env after CD4 engagement. These mAbs recognize three epitope clusters: cluster A, the gp120 face occluded by gp41 in trimeric Env; cluster B, a region proximal to the coreceptor-binding site (CoRBS) and involving the V1/V2 domain;more » and cluster C, the coreceptor-binding site. The mAbs were evaluated functionally by antibody-dependent, cell-mediated cytotoxicity (ADCC) and for neutralization of Tiers 1 and 2 pseudoviruses. All three clusters included mAbs mediating ADCC. However, there was a strong potency bias for cluster A, which harbors at least three potent ADCC epitopes whose cognate mAbs have electropositive paratopes. Cluster A epitopes are functional ADCC targets during viral entry in an assay format using virion-sensitized target cells. In contrast, only cluster C contained epitopes that were recognized by neutralizing mAbs. There was significant diversity in breadth and potency that correlated with epitope fine specificity. In contrast, ADCC potency had no relationship with neutralization potency or breadth for any epitope cluster. In conclusion, Fc-mediated effector function and neutralization coselect with specificity in anti-Env antibody responses, but the nature of selection is distinct for these two antiviral activities.« less

Modelling ultraviolet-line diagnostics of stars, the ionized and the neutral interstellar medium in star-forming galaxies

NASA Astrophysics Data System (ADS)

Vidal-García, A.; Charlot, S.; Bruzual, G.; Hubeny, I.

2017-09-01

We combine state-of-the-art models for the production of stellar radiation and its transfer through the interstellar medium (ISM) to investigate ultraviolet-line diagnostics of stars, the ionized and the neutral ISM in star-forming galaxies. We start by assessing the reliability of our stellar population synthesis modelling by fitting absorption-line indices in the ISM-free ultraviolet spectra of 10 Large Magellanic Cloud clusters. In doing so, we find that neglecting stochastic sampling of the stellar initial mass function in these young (∼10-100 Myr), low-mass clusters affects negligibly ultraviolet-based age and metallicity estimates but can lead to significant overestimates of stellar mass. Then, we proceed and develop a simple approach, based on an idealized description of the main features of the ISM, to compute in a physically consistent way the combined influence of nebular emission and interstellar absorption on ultraviolet spectra of star-forming galaxies. Our model accounts for the transfer of radiation through the ionized interiors and outer neutral envelopes of short-lived stellar birth clouds, as well as for radiative transfer through a diffuse intercloud medium. We use this approach to explore the entangled signatures of stars, the ionized and the neutral ISM in ultraviolet spectra of star-forming galaxies. We find that, aside from a few notable exceptions, most standard ultraviolet indices defined in the spectra of ISM-free stellar populations are prone to significant contamination by the ISM, which increases with metallicity. We also identify several nebular-emission and interstellar-absorption features, which stand out as particularly clean tracers of the different phases of the ISM.

Phase transitions and spatially ordered counterion association in ionic-lipid membranes: a statistical model.

PubMed

Tamashiro, M N; Barbetta, C; Germano, R; Henriques, V B

2011-09-01

We propose a statistical model to account for the gel-fluid anomalous phase transitions in charged bilayer- or lamellae-forming ionic lipids. The model Hamiltonian comprises effective attractive interactions to describe neutral-lipid membranes as well as the effect of electrostatic repulsions of the discrete ionic charges on the lipid headgroups. The latter can be counterion dissociated (charged) or counterion associated (neutral), while the lipid acyl chains may be in gel (low-temperature or high-lateral-pressure) or fluid (high-temperature or low-lateral-pressure) states. The system is modeled as a lattice gas with two distinct particle types--each one associated, respectively, with the polar-headgroup and the acyl-chain states--which can be mapped onto an Ashkin-Teller model with the inclusion of cubic terms. The model displays a rich thermodynamic behavior in terms of the chemical potential of counterions (related to added salt concentration) and lateral pressure. In particular, we show the existence of semidissociated thermodynamic phases related to the onset of charge order in the system. This type of order stems from spatially ordered counterion association to the lipid headgroups, in which charged and neutral lipids alternate in a checkerboard-like order. Within the mean-field approximation, we predict that the acyl-chain order-disorder transition is discontinuous, with the first-order line ending at a critical point, as in the neutral case. Moreover, the charge order gives rise to continuous transitions, with the associated second-order lines joining the aforementioned first-order line at critical end points. We explore the thermodynamic behavior of some physical quantities, like the specific heat at constant lateral pressure and the degree of ionization, associated with the fraction of charged lipid headgroups.

Difference in direct charge-parity violation between charged and neutral B meson decays.

PubMed

Lin, S-W; Unno, Y; Hou, W-S; Chang, P; Adachi, I; Aihara, H; Akai, K; Arinstein, K; Aulchenko, V; Aushev, T; Aziz, T; Bakich, A M; Balagura, V; Barberio, E; Bay, A; Bedny, I; Bitenc, U; Bondar, A; Bozek, A; Bracko, M; Browder, T E; Chang, M-C; Chao, Y; Chen, A; Chen, K-F; Chen, W T; Cheon, B G; Chiang, C-C; Chistov, R; Cho, I-S; Choi, S-K; Choi, Y; Choi, Y K; Cole, S; Dalseno, J; Danilov, M; Dash, M; Drutskoy, A; Eidelman, S; Epifanov, D; Fratina, S; Fujikawa, M; Furukawa, K; Gabyshev, N; Goldenzweig, P; Golob, B; Ha, H; Haba, J; Hara, T; Hayasaka, K; Hayashii, H; Hazumi, M; Heffernan, D; Hokuue, T; Hoshi, Y; Hsiung, Y B; Hyun, H J; Iijima, T; Ikado, K; Inami, K; Ishikawa, A; Ishino, H; Itoh, R; Iwabuchi, M; Iwasaki, M; Iwasaki, Y; Kah, D H; Kaji, H; Kataoka, S U; Kawai, H; Kawasaki, T; Kibayashi, A; Kichimi, H; Kikutani, E; Kim, H J; Kim, S K; Kim, Y J; Kinoshita, K; Korpar, S; Kozakai, Y; Krizan, P; Krokovny, P; Kumar, R; Kuo, C C; Kuzmin, A; Kwon, Y-J; Lee, M J; Lee, S E; Lesiak, T; Li, J; Liu, Y; Liventsev, D; Mandl, F; Marlow, D; McOnie, S; Medvedeva, T; Mimashi, T; Mitaroff, W; Miyabayashi, K; Miyake, H; Miyazaki, Y; Mizuk, R; Mori, T; Nakamura, T T; Nakano, E; Nakao, M; Nakazawa, H; Nishida, S; Nitoh, O; Noguchi, S; Nozaki, T; Ogawa, S; Ogawa, Y; Ohshima, T; Okuno, S; Olsen, S L; Ozaki, H; Pakhlova, G; Park, C W; Park, H; Peak, L S; Pestotnik, R; Peters, M; Piilonen, L E; Poluektov, A; Sahoo, H; Sakai, Y; Schneider, O; Schümann, J; Schwartz, A J; Seidl, R; Senyo, K; Sevior, M E; Shapkin, M; Shen, C P; Shibuya, H; Shidara, T; Shinomiya, S; Shiu, J-G; Shwartz, B; Singh, J B; Sokolov, A; Somov, A; Stanic, S; Staric, M; Sumisawa, K; Sumiyoshi, T; Suzuki, S; Tajima, O; Takasaki, F; Tamura, N; Tanaka, M; Tawada, M; Taylor, G N; Teramoto, Y; Tikhomirov, I; Trabelsi, K; Uehara, S; Ueno, K; Uglov, T; Uno, S; Urquijo, P; Ushiroda, Y; Usov, Y; Varner, G; Varvell, K E; Vervink, K; Villa, S; Wang, C C; Wang, C H; Wang, M-Z; Watanabe, Y; Wedd, R; Wicht, J; Won, E; Yabsley, B D; Yamaguchi, A; Yamashita, Y; Yamauchi, M; Yoshida, M; Yuan, C Z; Yusa, Y; Zhang, C C; Zhang, Z P; Zhilich, V; Zhulanov, V; Zupanc, A

2008-03-20

Equal amounts of matter and antimatter are predicted to have been produced in the Big Bang, but our observable Universe is clearly matter-dominated. One of the prerequisites for understanding this elimination of antimatter is the nonconservation of charge-parity (CP) symmetry. So far, two types of CP violation have been observed in the neutral K meson (K(0)) and B meson (B(0)) systems: CP violation involving the mixing between K(0) and its antiparticle (and likewise for B(0) and ), and direct CP violation in the decay of each meson. The observed effects for both types of CP violation are substantially larger for the B(0) meson system. However, they are still consistent with the standard model of particle physics, which has a unique source of CP violation that is known to be too small to account for the matter-dominated Universe. Here we report that the direct CP violation in charged B(+/-)-->K(+/-)pi(0) decay is different from that in the neutral B(0) counterpart. The direct CP-violating decay rate asymmetry, (that is, the difference between the number of observed B(-)-->K(-)pi(0) event versus B(+)-->K(+) pi(0) events, normalized to the sum of these events) is measured to be about +7%, with an uncertainty that is reduced by a factor of 1.7 from a previous measurement. However, the asymmetry for versus B(0)-->K(+)pi(-) is at the -10% level. Although it is susceptible to strong interaction effects that need further clarification, this large deviation in direct CP violation between charged and neutral B meson decays could be an indication of new sources of CP violation-which would help to explain the dominance of matter in the Universe.

Rapid Quantification of Low-Viscosity Acetyl-Triacylglycerols Using Electrospray Ionization Mass Spectrometry.

PubMed

Bansal, Sunil; Durrett, Timothy P

2016-09-01

Acetyl-triacylglycerols (acetyl-TAG) possess an sn-3 acetate group, which confers useful chemical and physical properties to these unusual triacylglycerols (TAG). Current methods for quantification of acetyl-TAG are time consuming and do not provide any information on the molecular species profile. Electrospray ionization mass spectrometry (ESI-MS)-based methods can overcome these drawbacks. However, the ESI-MS signal intensity for TAG depends on the aliphatic chain length and unsaturation index of the molecule. Therefore response factors for different molecular species need to be determined before any quantification. The effects of the chain length and the number of double-bonds of the sn-1/2 acyl groups on the signal intensity for the neutral loss of short chain length sn-3 groups were quantified using a series of synthesized sn-3 specific structured TAG. The signal intensity for the neutral loss of the sn-3 acyl group was found to negatively correlated with the aliphatic chain length and unsaturation index of the sn-1/2 acyl groups. The signal intensity of the neutral loss of the sn-3 acyl group was also negatively correlated with the size of that chain. Further, the position of the group undergoing neutral loss was also important, with the signal from an sn-2 acyl group much lower than that from one located at sn-3. Response factors obtained from these analyses were used to develop a method for the absolute quantification of acetyl-TAG. The increased sensitivity of this ESI-MS-based approach allowed successful quantification of acetyl-TAG in various biological settings, including the products of in vitro enzyme activity assays.

Flavor physics and CP violation

NASA Astrophysics Data System (ADS)

Chang, Paoti; Chen, Kai-Feng; Hou, Wei-Shu

2017-11-01

We currently live in the age of the CKM paradigm. The 3 × 3 matrix that links (d , s , b) quarks to (u , c , t) in the charged current weak interaction, being complex and nominally with 18 parameters, can be accounted for by just 3 rotation angles and one CP violating (CPV) phase, with unitarity and the CKM phases triumphantly tested at the B factories. But the CKM picture is unsatisfactory and has too many parameters. The main aim of Flavor Physics and CP violation (FPCP) studies is the pursuit to uncover New Physics beyond the Standard Model (SM). Two highlights of LHC Run 1 period are the CPV phase ϕs of Bs mixing and Bs →μ+μ- decay, which were found to be again consistent with SM, though the saga is yet unfinished. We also saw the emergence of the P5‧ angular variable anomaly in B0 →K∗0μ+μ- decay and R K (∗) anomaly in B →K (∗)μ+μ- to B →K (∗)e+e- rate ratios, and the BaBar anomaly in B →D (∗) τν decays, which suggest possible New Physics in these flavor processes, pointing to extra Z‧, charged Higgs, or leptoquarks. Charmless hadronic, semileptonic, purely leptonic and radiative B decays continue to offer various further windows on New Physics. Away from B physics, the rare K → πνν decays and ε‧ / ε in the kaon sector, μ → e transitions, muon g - 2 and electric dipole moments of the neutron and electron, τ → μγ , μμμ , eee, and a few charm physics probes, offer broadband frontier windows on New Physics. Lastly, flavor changing neutral transitions involving the top quark t and the 125 GeV Higgs boson h, such as t → ch and h → μτ, offer a new window into FPCP, while a new Z‧ related or inspired by the P5‧ anomaly, could show up in analogous top quark processes, perhaps even link with low energy phenomena such as muon g - 2 or rare kaon processes. In particular, we advocate the potential new SM, the two Higgs doublet model without discrete symmetries to control flavor violation, as SM2. As we are close to the alignment limit with h rather SM-like, flavor changing neutral Higgs couplings (FCNH) are suppressed by a small mixing angle, but the exotic Higgs doublet possesses FCNH couplings, which we are just starting to probe. As LHC Run 2 runs its course, and with Belle II B physics program to start soon, there is much to look forward to in the flavor and CPV sector.

Does facial attractiveness influence perception of epilepsy diagnosis? An insight into stigma in epilepsy.

PubMed

Ristić, Aleksandar J; Jovanović, Olja; Popadić, Dragan; Pađen, Višnja; Moosa, Ahsan N V; Krivokapić, Ana; Parojčić, Aleksandra; Berisavac, Ivana; Ilanković, Andrej; Baščarević, Vladimir; Vojvodić, Nikola; Sokić, Dragoslav

2017-12-01

Using a group of young healthy individuals and patients with multiple sclerosis (pMS), we aimed to investigate whether the physical attractiveness judgment affects perception of epilepsy. We tested hypothesis that subjects, in the absence of relevant clues, would catch upon the facial attractiveness when asked to speculate which person suffers epilepsy and select less attractive choices. Two photo-arrays (7 photos for each gender) selected from the Chicago Face Database (180 neutral faces of Caucasian volunteers with unknown medical status) were shown to study participants. Photos were evenly distributed along a continuum of attractiveness that was estimated by independent raters in prestudy stage. In each photo-array, three photos had rating 1-3 (unattractive), one photo had rating 4 (neutral), and three photos had rating 5-7 (attractive). High-quality printed photo-arrays were presented to test subjects, and they were asked to select one person from each photo-array "who has epilepsy". Finally, all subjects were asked to complete questionnaire of self-esteem and 19-item Scale of stereotypes toward people with epilepsy. In total, 71 students of psychology, anthropology, or andragogy (mean age: 21.6±1.7years; female: 85.9%) and 70 pMS (mean age: 37.9±8years; female: 71.4%) were tested. Majority of students or pMS had no previous personal experience with individuals with epilepsy (63.4%; 47.1%, p=0.052). Male photo was selected as epileptic in the following proportions: students - 84.5% unattractive, 8.5% neutral, and 7% attractive; pMS - 62.9% unattractive, 8.6% neutral, and 28.6% attractive (p=0.003). Female photo was selected as epileptic in the following proportions: students - 38% unattractive, 52.1% neutral, and 9.9% attractive; pMS - 32.9% unattractive, 34.3% neutral, and 32.9% attractive (0.003). Both groups showed very low potential for stigmatization: significantly lower in pMS in 10 items. Patients with multiple sclerosis showed significantly higher self-esteem than students (p=0.007). Facial attractiveness influences the perception of diagnosis of epilepsy. Both students and pMS were less willing to attribute epilepsy to attractive person of both genders. Copyright © 2017 Elsevier Inc. All rights reserved.

Selective and reusable iron(II)-based molecular sensor for the vapor-phase detection of alcohols.

PubMed

Naik, Anil D; Robeyns, Koen; Meunier, Christophe F; Léonard, Alexandre F; Rotaru, Aurelian; Tinant, Bernard; Filinchuk, Yaroslav; Su, Bao Lian; Garcia, Yann

2014-02-03

A mononuclear iron(II) neutral complex (1) is screened for sensing abilities for a wide spectrum of chemicals and to evaluate the response function toward physical perturbation like temperature and mechanical stress. Interestingly, 1 precisely detects methanol among an alcohol series. The sensing process is visually detectable, fatigue-resistant, highly selective, and reusable. The sensing ability is attributed to molecular sieving and subsequent spin-state change of iron centers, after a crystal-to-crystal transformation.

Measurement of the Characteristics of TIDs Using Small and Regional Networks of GPS Receivers during the Campaign of 17-30 July of 2008

DTIC Science & Technology

2012-01-01

Valladares1 andMatthew A. Hei2 1 Institute for Scientific Research, Boston College, Chestnut Hill, MA 02467, USA 2Plasma Physics Division, Naval Research...bubbles. 1 . Introduction Traveling ionospheric disturbances (TIDs) are the iono- spheric manifestation of neutral density oscillations called atmospheric...result [ 1 –3]. However, at night the electrodynamics are favorable to the production of “nonclassical” or “electrodynamic” TIDs, such that vertical

Asymptotic-Preserving methods and multiscale models for plasma physics

NASA Astrophysics Data System (ADS)

Degond, Pierre; Deluzet, Fabrice

2017-05-01

The purpose of the present paper is to provide an overview of Asymptotic-Preserving methods for multiscale plasma simulations by addressing three singular perturbation problems. First, the quasi-neutral limit of fluid and kinetic models is investigated in the framework of non-magnetized as well as magnetized plasmas. Second, the drift limit for fluid descriptions of thermal plasmas under large magnetic fields is addressed. Finally efficient numerical resolutions of anisotropic elliptic or diffusion equations arising in magnetized plasma simulation are reviewed.

Translations on USSR Science and Technology Physical Sciences and Technology, Number 2

DTIC Science & Technology

1976-11-04

causing them to re-enter and burn up in the dense layers of the atmosphere; By neutralizing their optical or infrared equipment by luminous or...Soviet satellites of the Cosmos series making a pass near other satellites, also of the Cosmos series, which were placed in orbit several days...mn), which was announced by the Tass Agency. On 20 October 1968 at 0740 GMT, Cosmos 249 made a pass near Cosmos 248. At this moment, Cosmos 249

Dissipative ion-cyclotron oscillitons in a form of solitons with chirp in Earth's low-altitude ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovaleva, I. Kh.

2012-10-15

In this paper, we consider theoretically nonlinear ion-cyclotron gradient-drift dissipative structures (oscillitons) in low ionospheric plasmas. Similar to Nonlinear Optics and Condensed Matter Physics, the Ginzburg-Landau equation for the envelope of electric wave fields is derived, and solutions for oscillitons in the form of solitons with chirp are examined. The whole dissipative structure constitutes a soliton with a moving charge-neutral density hump. Conditions for excitation and properties of the structures are considered.

Cold Antimatter Plasmas, and Aspirations for Cold Antihydrogen

DTIC Science & Technology

2002-06-24

comparison of any baryon and antibaryon by almost a factor of CP606, Non-Neutral Plasma Physics IV, edited by F. Anderegg et al. © 2002 American...antiprotons 3 _one-electron .1 eV quantum cyclotron 0.001 K FIGURE 1. Particle energies a million. An improved baryon CPT test (e.g. involving cold...more precise tests of CPT invariance with baryons and leptons than have been realized so far. The pursuit of cold antihydrogen thus began some time ago

The Benefits and Risks of Virtual Bidding in Multi-Settlement Markets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isemonger, Alan G.

2006-11-15

While it is possible that multi-settlement markets can exist without virtual trading, it is equally clear that virtual trading can provide many market benefits. The main one: In the absence of explicit virtual bidding (EVB), the price arbitrage trades that are benign in other commodity markets affect the reliability of the underlying electricity markets, resulting in a situation where EVB is most useful when it neutralizes the deleterious reliability effects of implicit virtual bidding and physical arbitrage. (author)

A Feasibility Study on the Control of a Generic Air Vehicle Using Control Moment Gyros

NASA Technical Reports Server (NTRS)

Lim, Kyong B.; Moerder, Daniel D.

2006-01-01

This paper examines feasibility and performance issues in using Control Moment Gyroscopes (CMGs) to control the attitude of a fixed-wing aircraft. The paper describes a control system structure that permits allocating control authority and bandwidth between a CMG system and conventional aerodynamic control surfaces to stabilize a vehicle with neutral aerodynamic stability. A simulation study explores the interplay between aerodynamic and CMG effects, and indicates desirable physical characteristics for a CMG system to be used for aircraft attitude control.