Size effects and realiability of barium strontium titanate thin films

NASA Astrophysics Data System (ADS)

Parker, Charles Bernard

Thin films of (Ba,Sr)TiO3 (BST) deposited by Liquid Source MOCVD were investigated. BST is a candidate dielectric for future-generation DRAM and as a tunable dielectric. Two areas of both scientific and commercial interest were investigated. The first area is the effect of decreasing dimension on ferroelectric properties. Several theories of size effects in ferroelectrics were evaluated. The dielectric response of a set of BST films of thicknesses from 15 to 580 nm was measured from 85 to 580 K. These films were extensively characterized and the boundary conditions that often influence size effects measurements were considered, including strain, finite screening length in the electrode, depolarization fields in the ferroelectric, atmospheric effects, control of stochiometry, and others. The data set was compared to the theoretical predictions and it was determined that Finite Size Scaling provided the best fit to the data. Using this theory, the predicted dielectric response was compared to the requirements of future generations of DRAM and was found to be sufficient, if film strain can be controlled. The second area is reliability. The types of lifetime-limiting electrical failure observed in BST are resistance degradation, time dependant dielectric breakdown (tddb), and noisy breakdown. Previous work on BST reliability has largely focused on resistance degradation at high temperature. This condition is only a small subset of experimental space. This work extends the understanding of BST failure into the low temperature regime and evaluates the effects of both DC and AC stress. It was found that tddb is the dominant failure mode at low temperature and resistance degradation is the dominant failure modes at high temperature. Synthesizing this work with previous work on resistance degradation allowed a failure framework to be developed. Rigorous extrapolation of resistance degradation and tddb lifetimes was compared to the requirements of future generations of DRAM and was found that while resistance degradation will not limit device lifetimes, tddb will. Refinement of BST processing will be necessary to reduce the defect causing tddb failure.

Self-organized criticality in asymmetric exclusion model with noise for freeway traffic

NASA Astrophysics Data System (ADS)

Nagatani, Takashi

1995-02-01

The one-dimensional asymmetric simple-exclusion model with open boundaries for parallel update is extended to take into account temporary stopping of particles. The model presents the traffic flow on a highway with temporary deceleration of cars. Introducing temporary stopping into the asymmetric simple-exclusion model drives the system asymptotically into a steady state exhibiting a self-organized criticality. In the self-organized critical state, start-stop waves (or traffic jams) appear with various sizes (or lifetimes). The typical interval < s>between consecutive jams scales as < s> ≃ Lv with v = 0.51 ± 0.05 where L is the system size. It is shown that the cumulative jam-interval distribution Ns( L) satisfies the finite-size scaling form ( Ns( L) ≃ L- vf( s/ Lv). Also, the typical lifetime ≃ Lv‧ with v‧ = 0.52 ± 0.05. The cumulative distribution Nm( L) of lifetimes satisfies the finite-size scaling form Nm( L)≃ L-1g( m/ Lv‧).

Analysis of imperfections in the coherent optical excitation of single atoms to Rydberg states

NASA Astrophysics Data System (ADS)

de Léséleuc, Sylvain; Barredo, Daniel; Lienhard, Vincent; Browaeys, Antoine; Lahaye, Thierry

2018-05-01

We study experimentally various physical limitations and technical imperfections that lead to damping and finite contrast of optically driven Rabi oscillations between ground and Rydberg states of a single atom. Finite contrast is due to preparation and detection errors, and we show how to model and measure them accurately. Part of these errors originates from the finite lifetime of Rydberg states, and we observe its n3 scaling with the principal quantum number n . To explain the damping of Rabi oscillations, we use simple numerical models taking into account independently measured experimental imperfections and show that the observed damping actually results from the accumulation of several small effects, each at the level of a few percent. We discuss prospects for improving the coherence of ground-Rydberg Rabi oscillations in view of applications in quantum simulation and quantum information processing with arrays of single Rydberg atoms.

Dynamics of DNA breathing: weak noise analysis, finite time singularity, and mapping onto the quantum Coulomb problem.

PubMed

Fogedby, Hans C; Metzler, Ralf

2007-12-01

We study the dynamics of denaturation bubbles in double-stranded DNA on the basis of the Poland-Scheraga model. We show that long time distributions for the survival of DNA bubbles and the size autocorrelation function can be derived from an asymptotic weak noise approach. In particular, below the melting temperature the bubble closure corresponds to a noisy finite time singularity. We demonstrate that the associated Fokker-Planck equation is equivalent to a quantum Coulomb problem. Below the melting temperature, the bubble lifetime is associated with the continuum of scattering states of the repulsive Coulomb potential; at the melting temperature, the Coulomb potential vanishes and the underlying first exit dynamics exhibits a long time power law tail; above the melting temperature, corresponding to an attractive Coulomb potential, the long time dynamics is controlled by the lowest bound state. Correlations and finite size effects are discussed.

Probabilistic Prediction of Lifetimes of Ceramic Parts

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Gyekenyesi, John P.; Jadaan, Osama M.; Palfi, Tamas; Powers, Lynn; Reh, Stefan; Baker, Eric H.

2006-01-01

ANSYS/CARES/PDS is a software system that combines the ANSYS Probabilistic Design System (PDS) software with a modified version of the Ceramics Analysis and Reliability Evaluation of Structures Life (CARES/Life) Version 6.0 software. [A prior version of CARES/Life was reported in Program for Evaluation of Reliability of Ceramic Parts (LEW-16018), NASA Tech Briefs, Vol. 20, No. 3 (March 1996), page 28.] CARES/Life models effects of stochastic strength, slow crack growth, and stress distribution on the overall reliability of a ceramic component. The essence of the enhancement in CARES/Life 6.0 is the capability to predict the probability of failure using results from transient finite-element analysis. ANSYS PDS models the effects of uncertainty in material properties, dimensions, and loading on the stress distribution and deformation. ANSYS/CARES/PDS accounts for the effects of probabilistic strength, probabilistic loads, probabilistic material properties, and probabilistic tolerances on the lifetime and reliability of the component. Even failure probability becomes a stochastic quantity that can be tracked as a response variable. ANSYS/CARES/PDS enables tracking of all stochastic quantities in the design space, thereby enabling more precise probabilistic prediction of lifetimes of ceramic components.

Universality classes of foraging with resource renewal

NASA Astrophysics Data System (ADS)

Chupeau, M.; Bénichou, O.; Redner, S.

2016-03-01

We determine the impact of resource renewal on the lifetime of a forager that depletes its environment and starves if it wanders too long without eating. In the framework of a minimal starving random-walk model with resource renewal, there are three universal classes of behavior as a function of the renewal time. For sufficiently rapid renewal, foragers are immortal, while foragers have a finite lifetime otherwise. In the specific case of one dimension, there is a third regime, for sufficiently slow renewal, in which the lifetime of the forager is independent of the renewal time. We outline an enumeration method to determine the mean lifetime of the forager in the mortal regime.

Optimal search strategies of space-time coupled random walkers with finite lifetimes

NASA Astrophysics Data System (ADS)

Campos, D.; Abad, E.; Méndez, V.; Yuste, S. B.; Lindenberg, K.

2015-05-01

We present a simple paradigm for detection of an immobile target by a space-time coupled random walker with a finite lifetime. The motion of the walker is characterized by linear displacements at a fixed speed and exponentially distributed duration, interrupted by random changes in the direction of motion and resumption of motion in the new direction with the same speed. We call these walkers "mortal creepers." A mortal creeper may die at any time during its motion according to an exponential decay law characterized by a finite mean death rate ωm. While still alive, the creeper has a finite mean frequency ω of change of the direction of motion. In particular, we consider the efficiency of the target search process, characterized by the probability that the creeper will eventually detect the target. Analytic results confirmed by numerical results show that there is an ωm-dependent optimal frequency ω =ωopt that maximizes the probability of eventual target detection. We work primarily in one-dimensional (d =1 ) domains and examine the role of initial conditions and of finite domain sizes. Numerical results in d =2 domains confirm the existence of an optimal frequency of change of direction, thereby suggesting that the observed effects are robust to changes in dimensionality. In the d =1 case, explicit expressions for the probability of target detection in the long time limit are given. In the case of an infinite domain, we compute the detection probability for arbitrary times and study its early- and late-time behavior. We further consider the survival probability of the target in the presence of many independent creepers beginning their motion at the same location and at the same time. We also consider a version of the standard "target problem" in which many creepers start at random locations at the same time.

Bilayer Suspension Plasma-Sprayed Thermal Barrier Coatings with Enhanced Thermal Cyclic Lifetime: Experiments and Modeling

NASA Astrophysics Data System (ADS)

Gupta, Mohit; Kumara, Chamara; Nylén, Per

2017-08-01

Suspension plasma spraying (SPS) has been shown as a promising process to produce porous columnar strain tolerant coatings for thermal barrier coatings (TBCs) in gas turbine engines. However, the highly porous structure is vulnerable to crack propagation, especially near the topcoat-bondcoat interface where high stresses are generated due to thermal cycling. A topcoat layer with high toughness near the topcoat-bondcoat interface could be beneficial to enhance thermal cyclic lifetime of SPS TBCs. In this work, a bilayer coating system consisting of first a dense layer near the topcoat-bondcoat interface followed by a porous columnar layer was fabricated by SPS using Yttria-stabilised zirconia suspension. The objective of this work was to investigate if the bilayer topcoat architecture could enhance the thermal cyclic lifetime of SPS TBCs through experiments and to understand the effect of the column gaps/vertical cracks and the dense layer on the generated stresses in the TBC during thermal cyclic loading through finite element modeling. The experimental results show that the bilayer TBC had significantly higher lifetime than the single-layer TBC. The modeling results show that the dense layer and vertical cracks are beneficial as they reduce the thermally induced stresses which thus increase the lifetime.

Shot noise as a measure of the lifetime and energy splitting of Majorana bound states

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

Lü, Hai-Feng; Guo, Zhen; Ke, Sha-Sha

We propose a scheme to measure the lifetime and energy splitting of a pair of Majorana bound states at the ends of a superconducting nanowire by using the shot noise in a dynamical channel blockade system. A quantum dot is coupled to one end of the wire and connected with two electron reservoirs. It is found that a finite Majorana energy splitting tends to produce a super-Poissonian shot noise, while Majorana relaxation process relieves the dynamical channel blockade and suppresses the noise Fano factor. When the dot energy level locates in the middle of the gap of topological superconductor, themore » Fano factor is independent on Majorana lifetime and Majorana energy splitting is thus extracted. For a finite energy splitting, we could evaluate the Majorana relaxation rate from the suppression of Fano factor. Under a realistic condition, the expected resolution of Majorana energy splitting and its relaxation rate calculated from our model are about 1μeV and 0.01−1μeV, respectively.« less

Thermal stress during RTP processes and its possible effect on the light induced degradation in Cz-Si wafers

NASA Astrophysics Data System (ADS)

Kouhlane, Yacine; Bouhafs, Djoudi; Khelifati, Nabil; Guenda, Abdelkader; Demagh, Nacer-Eddine; Demagh, Assia; Pfeiffer, Pierre; Mezghiche, Salah; Hetatache, Warda; Derkaoui, Fahima; Nasraoui, Chahinez; Nwadiaru, Ogechi Vivian

2018-04-01

In this study, the carrier lifetime variation of p-type boron-doped Czochralski silicon (Cz-Si) wafers was investigated after a direct rapid thermal processing (RTP). Two wafers were passivated by silicon nitride (SiNx:H) layers, deposited by a PECVD system on both surfaces. Then the wafers were subjected to an RTP cycle at a peak temperature of 620 °C. The first wafer was protected (PW) from the direct radiative heating of the RTP furnace by placing the wafer between two as-cut Cz-Si shield wafers during the heat processing. The second wafer was not protected (NPW) and followed the same RTP cycle procedure. The carrier lifetime τ eff was measured using the QSSPC technique before and after illumination for 5 h duration at 0.5 suns. The immediate results of the measured lifetime (τ RTP ) after the RTP process have shown a regeneration in the lifetime of the two wafers with the PW wafer exhibiting an important enhancement in τ RTP as compared to the NPW wafer. The QSSPC measurements have indicated a good stable lifetime (τ d ) and a weak degradation effect was observed in the case of the PW wafer as compared to their initial lifetime value. Interferometry technique analyses have shown an enhancement in the surface roughness for the NPW wafer as compared to the protected one. Additionally, to improve the correlation between the RTP heat radiation stress and the carrier lifetime behavior, a simulation of the thermal stress and temperature profile using the finite element method on the wafers surface at RTP peak temperature of 620 °C was performed. The results confirm the reduction of the thermal stress with less heat losses for the PW wafer. Finally, the proposed method can lead to improving the lifetime of wafers by an RTP process at minimum energy costs.

One method for life time estimation of a bucket wheel machine for coal moving

NASA Astrophysics Data System (ADS)

Vîlceanu, Fl; Iancu, C.

2016-08-01

Rehabilitation of outdated equipment with lifetime expired, or in the ultimate life period, together with high cost investments for their replacement, makes rational the efforts made to extend their life. Rehabilitation involves checking operational safety based on relevant expertise of metal structures supporting effective resistance and assessing the residual lifetime. The bucket wheel machine for coal constitute basic machine within deposits of coal of power plants. The estimate of remaining life can be done by checking the loading on the most stressed subassembly by Finite Element Analysis on a welding detail. The paper presents step-by-step the method of calculus applied in order to establishing the residual lifetime of a bucket wheel machine for coal moving using non-destructive methods of study (fatigue cracking analysis + FEA). In order to establish the actual state of machine and areas subject to study, was done FEA of this mining equipment, performed on the geometric model of mechanical analyzed structures, with powerful CAD/FEA programs. By applying the method it can be calculated residual lifetime, by extending the results from the most stressed area of the equipment to the entire machine, and thus saving time and money from expensive replacements.

Probalistic Finite Elements (PFEM) structural dynamics and fracture mechanics

NASA Technical Reports Server (NTRS)

Liu, Wing-Kam; Belytschko, Ted; Mani, A.; Besterfield, G.

1989-01-01

The purpose of this work is to develop computationally efficient methodologies for assessing the effects of randomness in loads, material properties, and other aspects of a problem by a finite element analysis. The resulting group of methods is called probabilistic finite elements (PFEM). The overall objective of this work is to develop methodologies whereby the lifetime of a component can be predicted, accounting for the variability in the material and geometry of the component, the loads, and other aspects of the environment; and the range of response expected in a particular scenario can be presented to the analyst in addition to the response itself. Emphasis has been placed on methods which are not statistical in character; that is, they do not involve Monte Carlo simulations. The reason for this choice of direction is that Monte Carlo simulations of complex nonlinear response require a tremendous amount of computation. The focus of efforts so far has been on nonlinear structural dynamics. However, in the continuation of this project, emphasis will be shifted to probabilistic fracture mechanics so that the effect of randomness in crack geometry and material properties can be studied interactively with the effect of random load and environment.

Epoch Lifetimes in the Dynamics of a Competing Population

NASA Astrophysics Data System (ADS)

Yeung, C. H.; Ma, Y. P.; Wong, K. Y. Michael

We propose a dynamical model of a competing population whose agents have a tendency to balance their decisions in time. The model is applicable to financial markets in which the agents trade with finite capital, or other multiagent systems such as routers in communication networks attempting to transmit multiclass traffic in a fair way. We find an oscillatory behavior due to the segregation of agents into two groups. Each group remains winning over epochs. The aggregation of smart agents is able to explain the lifetime distribution of epochs to 8 decades of probability. The existence of the super agents further refines the lifetime distribution of short epochs.

Lineshape theory of pigment-protein complexes: How the finite relaxation time of nuclei influences the exciton relaxation-induced lifetime broadening.

PubMed

Dinh, Thanh-Chung; Renger, Thomas

2016-07-21

In pigment-protein complexes, often the excited states are partially delocalized and the exciton-vibrational coupling in the basis of delocalized states contains large diagonal and small off-diagonal elements. This inequality may be used to introduce potential energy surfaces (PESs) of exciton states and to treat the inter-PES coupling in Markov and secular approximations. The resulting lineshape function consists of a Lorentzian peak that is broadened by the finite lifetime of the exciton states caused by the inter-PES coupling and a vibrational sideband that results from the mutual displacement of the excitonic PESs with respect to that of the ground state. So far analytical expressions have been derived that relate the exciton relaxation-induced lifetime broadening to the Redfield [T. Renger and R. A. Marcus, J. Chem. Phys. 116, 9997 (2002)] or modified Redfield [M. Schröder, U. Kleinekathöfer, and M. Schreiber, J. Chem. Phys. 124, 084903 (2006)] rate constants of exciton relaxation, assuming that intra-PES nuclear relaxation is fast compared to inter-PES transfer. Here, we go beyond this approximation and provide an analytical expression, termed Non-equilibrium Modified Redfield (NeMoR) theory, for the lifetime broadening that takes into account the finite nuclear relaxation time. In an application of the theory to molecular dimers, we find that, for a widely used experimental spectral density of the exciton-vibrational coupling of pigment-protein complexes, the NeMoR spectrum at low-temperatures (T < 150 K) is better approximated by Redfield than by modified Redfield theory. At room temperature, the lifetime broadening obtained with Redfield theory underestimates the NeMoR broadening, whereas modified Redfield theory overestimates it by a similar amount. A fortuitous error compensation in Redfield theory is found to explain the good performance of this theory at low temperatures. Since steady state spectra of PPCs are often measured at low temperatures, Redfield theory still provides a numerically efficient alternative to NeMoR theory. At higher temperatures, we suggest to use NeMoR theory, because it has the same numerical costs as modified Redfield theory, but is more accurate.

Non-stationary measurements of Chiral Magnetic Effect

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

Shevchenko, V.I., E-mail: vladimir.i.shevchenko@gmail.com

2013-12-15

We discuss the Chiral Magnetic Effect from the quantum theory of measurements point of view for non-stationary measurements. The effect of anisotropy for fluctuations of electric currents in a magnetic field is addressed. It is shown that anisotropy caused by nonzero axial chemical potential is indistinguishable in this framework from anisotropy caused by finite measurement time or finite lifetime of the magnetic field, and in all cases it is related to abelian triangle anomaly. Possible P-odd effects in central heavy-ion collisions (where the Chiral Magnetic Effect is absent) are discussed in this context. This paper is dedicated to the memorymore » of Professor Mikhail Polikarpov (1952–2013). -- Highlights: •Asymmetry in the response function for vector currents of massless fermions in the magnetic field is computed. •Asymmetry caused by axial chemical potential is practically indistinguishable from the one caused by non-stationarity. •The CME current is non-dissipative in the stationary case and dissipative in the non-stationary case. •Importance of studies of P-odd signatures in central collisions is emphasized.« less

Self-Organized Criticality and Scaling in Lifetime of Traffic Jams

NASA Astrophysics Data System (ADS)

Nagatani, Takashi

1995-01-01

The deterministic cellular automaton 184 (the one-dimensional asymmetric simple-exclusion model with parallel dynamics) is extended to take into account injection or extraction of particles. The model presents the traffic flow on a highway with inflow or outflow of cars.Introducing injection or extraction of particles into the asymmetric simple-exclusion model drives the system asymptotically into a steady state exhibiting a self-organized criticality. The typical lifetime of traffic jams scales as \\cong Lν with ν=0.65±0.04. It is shown that the cumulative distribution Nm (L) of lifetimes satisfies the finite-size scaling form Nm (L) \\cong L-1 f(m/Lν).

Influence of Initial Inclined Surface Crack on Estimated Residual Fatigue Lifetime of Railway Axle

NASA Astrophysics Data System (ADS)

Náhlík, Luboš; Pokorný, Pavel; Ševčík, Martin; Hutař, Pavel

2016-11-01

Railway axles are subjected to cyclic loading which can lead to fatigue failure. For safe operation of railway axles a damage tolerance approach taking into account a possible defect on railway axle surface is often required. The contribution deals with an estimation of residual fatigue lifetime of railway axle with initial inclined surface crack. 3D numerical model of inclined semi-elliptical surface crack in railway axle was developed and its curved propagation through the axle was simulated by finite element method. Presence of press-fitted wheel in the vicinity of initial crack was taken into account. A typical loading spectrum of railway axle was considered and residual fatigue lifetime was estimated by NASGRO approach. Material properties of typical axle steel EA4T were considered in numerical calculations and lifetime estimation.

Wear in ceramic on ceramic type lumbar total disc replacement: effect of radial clearance.

PubMed

Shankar, S; Kesavan, D

2015-01-01

The wear of the bearing surfaces of total disc replacement (TDR) is a key problem leads to reduction in the lifetime of the prosthesis and it mainly occurs due to the range of clearances of the articulating surface between the superior plate and core. The objective of this paper is to estimate the wear using finite element concepts considering the different radial clearances between the articulating surfaces of ceramic on ceramic type Lumbar Total Disc Replacement (LTDR). The finite element (FE) model was subjected to wear testing protocols according to loading profile of International Standards Organization (ISO) 18192 standards through 10 million cycles. The radial clearance value of 0.05 mm showed less volumetric wear when compared with other radial clearance values. Hence, low radial clearance values are suitable for LTDR to minimize the wear.

Finite Element Model Characterization Of Nano-Composite Thermal And Environmental Barrier Coatings

NASA Technical Reports Server (NTRS)

Yamada, Yoshiki; Zhu, Dongming

2011-01-01

Thermal and environmental barrier coatings have been applied for protecting Si based ceramic matrix composite components from high temperature environment in advanced gas turbine engines. It has been found that the delamination and lifetime of T/EBC systems generally depend on the initiation and propagation of surface cracks induced by the axial mechanical load in addition to severe thermal loads. In order to prevent T/EBC systems from surface cracking and subsequent delamination due to mechanical and thermal stresses, T/EBC systems reinforced with nano-composite architectures have showed promise to improve mechanical properties and provide a potential crack shielding mechanism such as crack bridging. In this study, a finite element model (FEM) was established to understand the potential beneficial effects of nano-composites systems such as SiC nanotube-reinforced oxide T/EBC systems.

Toric-boson model: Toward a topological quantum memory at finite temperature

NASA Astrophysics Data System (ADS)

Hamma, Alioscia; Castelnovo, Claudio; Chamon, Claudio

2009-06-01

We discuss the existence of stable topological quantum memory at finite temperature. At stake here is the fundamental question of whether it is, in principle, possible to store quantum information for macroscopic times without the intervention from the external world, that is, without error correction. We study the toric code in two dimensions with an additional bosonic field that couples to the defects, in the presence of a generic environment at finite temperature: the toric-boson model. Although the coupling constants for the bare model are not finite in the thermodynamic limit, the model has a finite spectrum. We show that in the topological phase, there is a finite temperature below which open strings are confined and therefore the lifetime of the memory can be made arbitrarily (polynomially) long in system size. The interaction with the bosonic field yields a long-range attractive force between the end points of open strings but leaves closed strings and topological order intact.

Emergent Electronic and Dielectric Properties of Interacting Nanoparticles at Finite Temperature

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

Greenwood, Arin R.; Voros, Marton; Giberti, Federico

Lead chalcogenide nanoparticle solids have been successfully integrated into certified solar cells and represent promising platforms for the design of novel photoabsorbers for photoelectrochemical cells. While much attention has been drawn to improving efficiency and device performance through altering the character of the individual nanoparticles, the role of interactions between nanoparticles is not yet well-understood. Using first-principles molecular dynamics and electronic structure calculations, we investigated the combined effect of temperature and interaction on functionalized lead chalcogenide nanoparticles (NPs). Here, we show that at finite temperature, interacting NPs are dynamical dipolar systems, with the average values of dipole moments and polarizabilitiesmore » substantially increased with respect to those of the isolated building blocks. In addition, we show that the interacting NPs exhibit slightly smaller fundamental gaps that decrease as a function of temperature and that the radiative lifetimes of both the isolated NPs and the solids are greatly reduced at finite temperature compared to T = 0. Lastly, we present a critical discussion of various results reported in the literature for the values of dipole moments of nanoparticles.« less

Emergent Electronic and Dielectric Properties of Interacting Nanoparticles at Finite Temperature

DOE PAGES

Greenwood, Arin R.; Voros, Marton; Giberti, Federico; ...

2017-12-11

Lead chalcogenide nanoparticle solids have been successfully integrated into certified solar cells and represent promising platforms for the design of novel photoabsorbers for photoelectrochemical cells. While much attention has been drawn to improving efficiency and device performance through altering the character of the individual nanoparticles, the role of interactions between nanoparticles is not yet well-understood. Using first-principles molecular dynamics and electronic structure calculations, we investigated the combined effect of temperature and interaction on functionalized lead chalcogenide nanoparticles (NPs). Here, we show that at finite temperature, interacting NPs are dynamical dipolar systems, with the average values of dipole moments and polarizabilitiesmore » substantially increased with respect to those of the isolated building blocks. In addition, we show that the interacting NPs exhibit slightly smaller fundamental gaps that decrease as a function of temperature and that the radiative lifetimes of both the isolated NPs and the solids are greatly reduced at finite temperature compared to T = 0. Lastly, we present a critical discussion of various results reported in the literature for the values of dipole moments of nanoparticles.« less

Lineshape theory of pigment-protein complexes: How the finite relaxation time of nuclei influences the exciton relaxation-induced lifetime broadening

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

Dinh, Thanh-Chung; Renger, Thomas, E-mail: thomas.renger@jku.at

2016-07-21

In pigment-protein complexes, often the excited states are partially delocalized and the exciton-vibrational coupling in the basis of delocalized states contains large diagonal and small off-diagonal elements. This inequality may be used to introduce potential energy surfaces (PESs) of exciton states and to treat the inter-PES coupling in Markov and secular approximations. The resulting lineshape function consists of a Lorentzian peak that is broadened by the finite lifetime of the exciton states caused by the inter-PES coupling and a vibrational sideband that results from the mutual displacement of the excitonic PESs with respect to that of the ground state. Somore » far analytical expressions have been derived that relate the exciton relaxation-induced lifetime broadening to the Redfield [T. Renger and R. A. Marcus, J. Chem. Phys. 116, 9997 (2002)] or modified Redfield [M. Schröder, U. Kleinekathöfer, and M. Schreiber, J. Chem. Phys. 124, 084903 (2006)] rate constants of exciton relaxation, assuming that intra-PES nuclear relaxation is fast compared to inter-PES transfer. Here, we go beyond this approximation and provide an analytical expression, termed Non-equilibrium Modified Redfield (NeMoR) theory, for the lifetime broadening that takes into account the finite nuclear relaxation time. In an application of the theory to molecular dimers, we find that, for a widely used experimental spectral density of the exciton-vibrational coupling of pigment-protein complexes, the NeMoR spectrum at low-temperatures (T < 150 K) is better approximated by Redfield than by modified Redfield theory. At room temperature, the lifetime broadening obtained with Redfield theory underestimates the NeMoR broadening, whereas modified Redfield theory overestimates it by a similar amount. A fortuitous error compensation in Redfield theory is found to explain the good performance of this theory at low temperatures. Since steady state spectra of PPCs are often measured at low temperatures, Redfield theory still provides a numerically efficient alternative to NeMoR theory. At higher temperatures, we suggest to use NeMoR theory, because it has the same numerical costs as modified Redfield theory, but is more accurate.« less

A Superconducting Magnet UCN Trap for Precise Neutron Lifetime Measurements.

PubMed

Picker, R; Altarev, I; Bröcker, J; Gutsmiedl, E; Hartmann, J; Müller, A; Paul, S; Schott, W; Trinks, U; Zimmer, O

2005-01-01

Finite-element methods along with Monte Carlo simulations were used to design a magnetic storage device for ultracold neutrons (UCN) to measure their lifetime. A setup was determined which should make it possible to confine UCN with negligible losses and detect the protons emerging from β-decay with high efficiency: stacked superconducting solenoids create the magnetic storage field, an electrostatic extraction field inside the storage volume assures high proton collection efficiency. Alongside with the optimization of the magnetic and electrostatic design, the properties of the trap were investigated through extensive Monte Carlo simulation.

Life-times of quantum resonances through the Geometrical Phase Propagator Approach

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

Pavlou, G.E.; Karanikas, A.I.; Diakonos, F.K., E-mail: fdiakono@phys.uoa.gr

We employ the recently introduced Geometric Phase Propagator Approach (GPPA) (Diakonos et al., 2012) to develop an improved perturbative scheme for the calculation of life times in driven quantum systems. This incorporates a resummation of the contributions of virtual processes starting and ending at the same state in the considered time interval. The proposed procedure allows for a strict determination of the conditions leading to finite life times in a general driven quantum system by isolating the resummed terms in the perturbative expansion contributing to their generation. To illustrate how the derived conditions apply in practice, we consider the effect ofmore » driving in a system with purely discrete energy spectrum, as well as in a system for which the eigenvalue spectrum contains a continuous part. We show that in the first case, when the driving contains a dense set of frequencies acting as a noise to the system, the corresponding bound states acquire a finite life time. When the energy spectrum contains also a continuum set of eigenvalues then the bound states, due to the driving, couple to the continuum and become quasi-bound resonances. The benchmark of this change is the appearance of a Fano-type peak in the associated transmission profile. In both cases the corresponding life-time can be efficiently estimated within the reformulated GPPA approach.« less

Broadband and broadangle SPP antennas based on plasmonic crystals with linear chirp.

PubMed

Bouillard, J-S; Vilain, S; Dickson, W; Wurtz, G A; Zayats, A V

2012-01-01

Plasmonic technology relies on the coupling of light to surface electromagnetic modes on smooth or structured metal surfaces. While some applications utilise the resonant nature of surface polaritons, others require broadband characteristics. We demonstrate unidirectional and broadband plasmonic antennas with large acceptance angles based on chirped plasmonic gratings. Near-field optical measurements have been used to visualise the excitation of surface plasmon polaritons by such aperiodic structures. These weakly aperiodic plasmonic crystals allow the formation of a trapped rainbow-type effect in a two-dimensional geometry as surface polaritons of different frequencies are coherently excited in different locations over the plasmonic structure. Both the crystal's finite size and the finite lifetime of plasmonic states are crucial for the generation of broadband surface plasmon polaritons. This approach presents new opportunities for building unidirectional, broadband and broad-angle plasmonic couplers for sensing purposes, information processing, photovoltaic applications and shaping and manipulating ultrashort optical pulses.

Broadband and broadangle SPP antennas based on plasmonic crystals with linear chirp

PubMed Central

Bouillard, J.-S; Vilain, S.; Dickson, W.; Wurtz, G. A.; Zayats, A. V.

2012-01-01

Plasmonic technology relies on the coupling of light to surface electromagnetic modes on smooth or structured metal surfaces. While some applications utilise the resonant nature of surface polaritons, others require broadband characteristics. We demonstrate unidirectional and broadband plasmonic antennas with large acceptance angles based on chirped plasmonic gratings. Near-field optical measurements have been used to visualise the excitation of surface plasmon polaritons by such aperiodic structures. These weakly aperiodic plasmonic crystals allow the formation of a trapped rainbow-type effect in a two-dimensional geometry as surface polaritons of different frequencies are coherently excited in different locations over the plasmonic structure. Both the crystal's finite size and the finite lifetime of plasmonic states are crucial for the generation of broadband surface plasmon polaritons. This approach presents new opportunities for building unidirectional, broadband and broad-angle plasmonic couplers for sensing purposes, information processing, photovoltaic applications and shaping and manipulating ultrashort optical pulses. PMID:23170197

Exploration and Trapping of Mortal Random Walkers

NASA Astrophysics Data System (ADS)

Yuste, S. B.; Abad, E.; Lindenberg, Katja

2013-05-01

Exploration and trapping properties of random walkers that may evanesce at any time as they walk have seen very little treatment in the literature, and yet a finite lifetime is a frequent occurrence, and its effects on a number of random walk properties may be profound. For instance, whereas the average number of distinct sites visited by an immortal walker grows with time without bound, that of a mortal walker may, depending on dimensionality and rate of evanescence, remain finite or keep growing with the passage of time. This number can in turn be used to calculate other classic quantities such as the survival probability of a target surrounded by diffusing traps. If the traps are immortal, the survival probability will vanish with increasing time. However, if the traps are evanescent, the target may be spared a certain death. We analytically calculate a number of basic and broadly used quantities for evanescent random walkers.

High-energy surface and volume plasmons in nanopatterned sub-10 nm aluminum nanostructures

DOE PAGES

Hobbs, Richard G.; Manfrinato, Vitor R.; Yang, Yujia; ...

2016-06-13

In this paper, we use electron energy-loss spectroscopy to map the complete plasmonic spectrum of aluminum nanodisks with diameters ranging from 3 to 120 nm fabricated by high-resolution electron-beam lithography. Our nanopatterning approach allows us to produce localized surface plasmon resonances across a wide spectral range spanning 2–8 eV. Electromagnetic simulations using the finite element method support the existence of dipolar, quadrupolar, and hexapolar surface plasmon modes as well as centrosymmetric breathing modes depending on the location of the electron-beam excitation. In addition, we have developed an approach using nanolithography that is capable of meV control over the energy andmore » attosecond control over the lifetime of volume plasmons in these nanodisks. The precise measurement of volume plasmon lifetime may also provide an opportunity to probe and control the DC electrical conductivity of highly confined metallic nanostructures. Lastly, we show the strong influence of the nanodisk boundary in determining both the energy and lifetime of surface plasmons and volume plasmons locally across individual aluminum nanodisks, and we have compared these observations to similar effects produced by scaling the nanodisk diameter.« less

Stress and deformation analysis of double curvature arc dams using finite element method (FEM): A case of budhi gandaki hydropower project

NASA Astrophysics Data System (ADS)

Mishra, Aanand Kumar; Singh, Ajay; Bahadur Singh, Akal

2018-06-01

High rise arc dams are widely used in the development of storage type hydropower project because of the economic advantage. Among different phases considered during the lifetime of dam, control of dam’s safety and performance becomes more concerned during the lifetime. This paper proposed the 3 – D finite element method (FEM) for stress and deformation analysis of double curvature arc dam considering the non – linearity of foundation rock following the Hoek – Brown Criterion. The proposed methodology is implemented through MATLAB scripting language and studied the double curvature arc dam proposed for Budhi Gandaki hydropower project. The stress developed in the foundation rock, compressive and tensile stress acting on the dam are investigated and analysed for the reservoir level variation. Deformation at the top of the dam and in the foundation rock is also investigated. In addition to that, stress and deformation variation in the foundation rock is analysed for various rock properties.

Intrinsic autocorrelation time of picoseconds for thermal noise in water.

PubMed

Zhu, Zhi; Sheng, Nan; Wan, Rongzheng; Fang, Haiping

2014-10-02

Whether thermal noise is colored or white is of fundamental importance. In conventional theory, thermal noise is usually treated as white noise so that there are no directional transportations in the asymmetrical systems without external inputs, since only the colored fluctuations with appropriate autocorrelation time length can lead to directional transportations in the asymmetrical systems. Here, on the basis of molecular dynamics simulations, we show that the autocorrelation time length of thermal noise in water is ~10 ps at room temperature, which indicates that thermal noise is not white in the molecular scale while thermal noise can be reasonably assumed as white in macro- and meso-scale systems. The autocorrelation time length of thermal noise is intrinsic, since the value is almost unchanged for different temperature coupling methods. Interestingly, the autocorrelation time of thermal noise is correlated with the lifetime of hydrogen bonds, suggesting that the finite autocorrelation time length of thermal noise mainly comes from the finite lifetime of the interactions between neighboring water molecules.

Design of Bioprosthetic Aortic Valves using biaxial test data.

PubMed

Dabiri, Y; Paulson, K; Tyberg, J; Ronsky, J; Ali, I; Di Martino, E; Narine, K

2015-01-01

Bioprosthetic Aortic Valves (BAVs) do not have the serious limitations of mechanical aortic valves in terms of thrombosis. However, the lifetime of BAVs is too short, often requiring repeated surgeries. The lifetime of BAVs might be improved by using computer simulations of the structural behavior of the leaflets. The goal of this study was to develop a numerical model applicable to the optimization of durability of BAVs. The constitutive equations were derived using biaxial tensile tests. Using a Fung model, stress and strain data were computed from biaxial test data. SolidWorks was used to develop the geometry of the leaflets, and ABAQUS finite element software package was used for finite element calculations. Results showed the model is consistent with experimental observations. Reaction forces computed by the model corresponded with experimental measurements when the biaxial test was simulated. As well, the location of maximum stresses corresponded to the locations of frequent tearing of BAV leaflets. Results suggest that BAV design can be optimized with respect to durability.

Magnetospheric Whistler Mode Raytracing with the Inclusion of Finite Electron and ion Temperature

NASA Astrophysics Data System (ADS)

Maxworth, Ashanthi S.

Whistler mode waves are a type of a low frequency (100 Hz - 30 kHz) wave, which exists only in a magnetized plasma. These waves play a major role in Earth's magnetosphere. Due to the impact of whistler mode waves in many fields such as space weather, satellite communications and lifetime of space electronics, it is important to accurately predict the propagation path of these waves. The method used to determine the propagation path of whistler waves is called numerical raytracing. Numerical raytracing determines the power flow path of the whistler mode waves by solving a set of equations known as the Haselgrove's equations. In the majority of the previous work, raytracing was implemented assuming a cold background plasma (0 K), but the actual magnetosphere is at a temperature of about 1 eV (11600 K). In this work we have modified the numerical raytracing algorithm to work at finite electron and ion temperatures. The finite temperature effects have also been introduced into the formulations for linear cyclotron resonance wave growth and Landau damping, which are the primary mechanisms for whistler mode growth and attenuation in the magnetosphere. Including temperature increases the complexity of numerical raytracing, but the overall effects are mostly limited to increasing the group velocity of the waves at highly oblique wave normal angles.

Design principles for high efficiency small-grain polysilicon solar cells, with supporting experimental studies

NASA Technical Reports Server (NTRS)

Lindholm, F. A.; Neugroschel, A.; Sah, C. T.

1982-01-01

Design principles suggested here aim toward high conversion efficiency (greater than 15 percent) in polysilicon cells. The principles seek to decrease the liabilities of both intragranular and grain-boundary-surface defects. The advantages of a phosphorus atom concentration gradient in a thin (less than 50 microns) base of a p(+)/n(x)/n(+) drift-field solar cell, which produces favorable gradients in chemical potential, minority-carrier mobility and diffusivity, and recombination lifetime (via phosphorus gettering) are suggested. The degrading effects of grain boundaries are reduced by these three gradients and by substituting atoms (P, H, F or Li) for vacancies on the grain-boundary surface. From recent experiments comes support for the benefits of P diffusion down grain boundaries and, for quasi-grain-boundary-free and related structures. New analytic solutions for the n(x)-base include the effect of a power-law dependence between P concentration and lifetime. These provide an upper-bound estimate on the open circuit voltage. Finite-difference numerical solutions of the six Shockley equations furnish complete information about all solar-cell parameters and add insight concerning design.

CURRENT AND EMERGING TECHNOLOGIES FOR EXTENDING THE LIFETIME OF ELECTROLESS NICKEL PLATING BATHS

EPA Science Inventory

The waste treatment and rejuvenation of spent electroless nickel baths has attracted a considerable amount of interest from electroplating shops, electroless nickel suppliers, universities and regulatory agencies due to the finite life of the baths and the associated waste that t...

Multicomponent exciton gas in cuprous oxide: cooling behaviour and the role of Auger decay

NASA Astrophysics Data System (ADS)

Semkat, D.; Sobkowiak, S.; Schöne, F.; Stolz, H.; Koch, Th; Fehske, H.

2017-10-01

In this paper we present a hydrodynamic model to describe the dynamics of para- and orthoexcitons in cuprous oxide at ultralow temperatures inside a stress induced potential trap. We take into account the finite lifetime of the excitons, the excitation process and exciton-phonon as well as exciton-exciton interaction. Furthermore, we model the two-body loss mechanism assuming an Auger-like effect and compare it to an alternative explanation which relies on the formation of biexcitons. We discuss in detail the influence on the numerical results and compare the predictions to experimental data.

GW electronic Correlations in Quantum Transport : Renormalization and finite lifetime effects on real systems

NASA Astrophysics Data System (ADS)

Darancet, Pierre; Ferretti, Andrea; Mayou, Didier; Olevano, Valerio

2007-03-01

We present an ab initio approach to electronic transport in nanoscale systems which includes electronic correlations through the GW approximation. With respect to Landauer approaches based on density-functional theory (DFT), we introduce a physical quasiparticle electronic-structure into a non-equilibrium Green's function theory framework. We use an equilibrium non-selfconsistent G^0W^0 self-energy considering both full non-hermiticity and dynamical effects. The method is applied to a real system, a gold mono-atomic chain. With respect to DFT results, the conductance profile is modified and reduced by to the introduction of diffusion and loss-of-coherence effects. The linear response conductance characteristic appear to be in agreement with experimental results.

Kinetic description of finite-wall catalysis for monatomic molecular recombination

NASA Astrophysics Data System (ADS)

Yano, Ryosuke; Suzuki, Kojiro

2011-11-01

In our previous study on hypothetical diatomic molecular dissociation and monatomic molecular recombination, A2 + M ↔ A + A + M [Yano et al., Phys. Fluids 21, 127101 (2009)], the interaction between the wall and A2* intermediates was not formulated. In this paper, we consider the effect of finite-wall catalysis on recombination of a monatomic molecule A via the interaction between the wall and A2*. According to the proposed Boltzmann model equation, the catalytic recombination rate depends on two quantities; the vibrational temperature and the translational temperature of A2* intermediates that are emitted from the wall. In particular, the translational temperature of A2* is related to its lifetime. In this paper, we investigate the change in the catalytic recombination rate of A upon changing the vibrational temperature of A2* intermediates that are emitted from the wall. As an object of analysis, the rarefied hypersonic flow around a cylinder with a finite wall-catalysis is considered using the proposed Boltzmann model equation. Numerical results confirm that a decrease in the vibrational temperature of A2* intermediates that are emitted from the wall results in an increase in recombination of A near the wall.

Short-ranged memory model with preferential growth

NASA Astrophysics Data System (ADS)

Schaigorodsky, Ana L.; Perotti, Juan I.; Almeira, Nahuel; Billoni, Orlando V.

2018-02-01

In this work we introduce a variant of the Yule-Simon model for preferential growth by incorporating a finite kernel to model the effects of bounded memory. We characterize the properties of the model combining analytical arguments with extensive numerical simulations. In particular, we analyze the lifetime and popularity distributions by mapping the model dynamics to corresponding Markov chains and branching processes, respectively. These distributions follow power laws with well-defined exponents that are within the range of the empirical data reported in ecologies. Interestingly, by varying the innovation rate, this simple out-of-equilibrium model exhibits many of the characteristics of a continuous phase transition and, around the critical point, it generates time series with power-law popularity, lifetime and interevent time distributions, and nontrivial temporal correlations, such as a bursty dynamics in analogy with the activity of solar flares. Our results suggest that an appropriate balance between innovation and oblivion rates could provide an explanatory framework for many of the properties commonly observed in many complex systems.

Short-ranged memory model with preferential growth.

PubMed

Schaigorodsky, Ana L; Perotti, Juan I; Almeira, Nahuel; Billoni, Orlando V

2018-02-01

In this work we introduce a variant of the Yule-Simon model for preferential growth by incorporating a finite kernel to model the effects of bounded memory. We characterize the properties of the model combining analytical arguments with extensive numerical simulations. In particular, we analyze the lifetime and popularity distributions by mapping the model dynamics to corresponding Markov chains and branching processes, respectively. These distributions follow power laws with well-defined exponents that are within the range of the empirical data reported in ecologies. Interestingly, by varying the innovation rate, this simple out-of-equilibrium model exhibits many of the characteristics of a continuous phase transition and, around the critical point, it generates time series with power-law popularity, lifetime and interevent time distributions, and nontrivial temporal correlations, such as a bursty dynamics in analogy with the activity of solar flares. Our results suggest that an appropriate balance between innovation and oblivion rates could provide an explanatory framework for many of the properties commonly observed in many complex systems.

Mahan polaritons and their lifetime due to hole recoil

NASA Astrophysics Data System (ADS)

Baeten, Maarten; Wouters, Michiel

2015-11-01

We present a theoretical study on polaritons in doped semiconductor microcavities, focussing on a cavity mode that is resonant with the Fermi edge. In agreement with experimental results, the strong light-matter coupling is maintained under very high doping within our ladder diagram approximation. In particular, we find that the polaritons result from the strong admixing of the cavity mode with the Mahan exciton. The upper Mahan polariton, lying in the electron-hole continuum, always remains visible and has a linewidth due to free interband electron-hole creation. The lower Mahan polariton acquires a finite lifetime due to relaxation of the valence band hole if the electron density exceeds a certain critical value. However, if the Rabi splitting exceeds the inverse hole recoil time, the lower polariton lifetime is only limited by the cavity properties.

Extreme value statistics and finite-size scaling at the ecological extinction/laminar-turbulence transition

NASA Astrophysics Data System (ADS)

Shih, Hong-Yan; Goldenfeld, Nigel

Experiments on transitional turbulence in pipe flow seem to show that turbulence is a transient metastable state since the measured mean lifetime of turbulence puffs does not diverge asymptotically at a critical Reynolds number. Yet measurements reveal that the lifetime scales with Reynolds number in a super-exponential way reminiscent of extreme value statistics, and simulations and experiments in Couette and channel flow exhibit directed percolation type scaling phenomena near a well-defined transition. This universality class arises from the interplay between small-scale turbulence and a large-scale collective zonal flow, which exhibit predator-prey behavior. Why is asymptotically divergent behavior not observed? Using directed percolation and a stochastic individual level model of predator-prey dynamics related to transitional turbulence, we investigate the relation between extreme value statistics and power law critical behavior, and show that the paradox is resolved by carefully defining what is measured in the experiments. We theoretically derive the super-exponential scaling law, and using finite-size scaling, show how the same data can give both super-exponential behavior and power-law critical scaling.

FDTD and transfer matrix methods for evaluating the performance of photonic crystal based microcavities for exciton-polaritons

NASA Astrophysics Data System (ADS)

Liu, Yi-Cheng; Byrnes, Tim

2016-11-01

We investigate alternative microcavity structures for exciton-polaritons consisting of photonic crystals instead of distributed Bragg reflectors. Finite-difference time-domain simulations and scattering transfer matrix methods are used to evaluate the cavity performance. The results are compared with conventional distributed Bragg reflectors. We find that in terms of the photon lifetime, the photonic crystal based microcavities are competitive, with typical lifetimes in the region of ∼20 ps being achieved. The photonic crystal microcavities have the advantage that they are compact and are frequency adjustable, showing that they are viable to investigate exciton-polariton condensation physics.

Life, the Universe, and Nothing: Life and Death in an Ever-expanding Universe

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

Krauss, Lawrence M.; Starkman, Glenn D.

2000-03-01

Current evidence suggests that the cosmological constant is not zero, or that we live in an open universe. We examine the implications for the future under these assumptions, and find that they are striking. If the universe is cosmological constant-dominated, our ability to probe the evolution of large-scale structure will decrease with time; presently observable distant sources will disappear on a timescale comparable to the period of stellar burning. Moreover, while the universe might expand forever, the integrated conscious lifetime of any civilization will be finite, although it can be astronomically long. We argue that this latter result is farmore » more general. In the absence of possible exotic and uncertain strong gravitational effects, the total information recoverable by any civilization over the entire history of our universe is finite. Assuming that consciousness has a physical computational basis, and therefore is ultimately governed by quantum mechanics, life cannot be eternal. (c) 2000 The American Astronomical Society.« less

Life Predicted in a Probabilistic Design Space for Brittle Materials With Transient Loads

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Palfi, Tamas; Reh, Stefan

2005-01-01

Analytical techniques have progressively become more sophisticated, and now we can consider the probabilistic nature of the entire space of random input variables on the lifetime reliability of brittle structures. This was demonstrated with NASA s CARES/Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code combined with the commercially available ANSYS/Probabilistic Design System (ANSYS/PDS), a probabilistic analysis tool that is an integral part of the ANSYS finite-element analysis program. ANSYS/PDS allows probabilistic loads, component geometry, and material properties to be considered in the finite-element analysis. CARES/Life predicts the time dependent probability of failure of brittle material structures under generalized thermomechanical loading--such as that found in a turbine engine hot-section. Glenn researchers coupled ANSYS/PDS with CARES/Life to assess the effects of the stochastic variables of component geometry, loading, and material properties on the predicted life of the component for fully transient thermomechanical loading and cyclic loading.

Symmetry-breaking dynamics of the finite-size Lipkin-Meshkov-Glick model near ground state

NASA Astrophysics Data System (ADS)

Huang, Yi; Li, Tongcang; Yin, Zhang-qi

2018-01-01

We study the dynamics of the Lipkin-Meshkov-Glick (LMG) model with a finite number of spins. In the thermodynamic limit, the ground state of the LMG model with an isotropic Hamiltonian in the broken phase breaks to a mean-field ground state with a certain direction. However, when the spin number N is finite, the exact ground state is always unique and is not given by a classical mean-field ground state. Here, we prove that when N is large but finite, through a tiny external perturbation, a localized state which is close to a mean-field ground state can be prepared, which mimics spontaneous symmetry breaking. Also, we find the localized in-plane spin polarization oscillates with two different frequencies ˜O (1 /N ) , and the lifetime of the localized state is long enough to exhibit this oscillation. We numerically test the analytical results and find that they agree very well with each other. Finally, we link the phenomena to quantum time crystals and time quasicrystals.

KINETICS OF LOW SOURCE REACTOR STARTUPS. PART II

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

hurwitz, H. Jr.; MacMillan, D.B.; Smith, J.H.

1962-06-01

A computational technique is described for computation of the probability distribution of power level for a low source reactor startup. The technique uses a mathematical model, for the time-dependent probability distribution of neutron and precursor concentration, having finite neutron lifetime, one group of delayed neutron precursors, and no spatial dependence. Results obtained by the technique are given. (auth)

A validated approach for modeling collapse of steel structures

NASA Astrophysics Data System (ADS)

Saykin, Vitaliy Victorovich

A civil engineering structure is faced with many hazardous conditions such as blasts, earthquakes, hurricanes, tornadoes, floods, and fires during its lifetime. Even though structures are designed for credible events that can happen during a lifetime of the structure, extreme events do happen and cause catastrophic failures. Understanding the causes and effects of structural collapse is now at the core of critical areas of national need. One factor that makes studying structural collapse difficult is the lack of full-scale structural collapse experimental test results against which researchers could validate their proposed collapse modeling approaches. The goal of this work is the creation of an element deletion strategy based on fracture models for use in validated prediction of collapse of steel structures. The current work reviews the state-of-the-art of finite element deletion strategies for use in collapse modeling of structures. It is shown that current approaches to element deletion in collapse modeling do not take into account stress triaxiality in vulnerable areas of the structure, which is important for proper fracture and element deletion modeling. The report then reviews triaxiality and its role in fracture prediction. It is shown that fracture in ductile materials is a function of triaxiality. It is also shown that, depending on the triaxiality range, different fracture mechanisms are active and should be accounted for. An approach using semi-empirical fracture models as a function of triaxiality are employed. The models to determine fracture initiation, softening and subsequent finite element deletion are outlined. This procedure allows for stress-displacement softening at an integration point of a finite element in order to subsequently remove the element. This approach avoids abrupt changes in the stress that would create dynamic instabilities, thus making the results more reliable and accurate. The calibration and validation of these models are shown. The calibration is performed using a particle swarm optimization algorithm to establish accurate parameters when calibrated to circumferentially notched tensile coupons. It is shown that consistent, accurate predictions are attained using the chosen models. The variation of triaxiality in steel material during plastic hardening and softening is reported. The range of triaxiality in steel structures undergoing collapse is investigated in detail and the accuracy of the chosen finite element deletion approaches is discussed. This is done through validation of different structural components and structural frames undergoing severe fracture and collapse.

Rescue of endemic states in interconnected networks with adaptive coupling

NASA Astrophysics Data System (ADS)

Vazquez, F.; Serrano, M. Ángeles; Miguel, M. San

2016-07-01

We study the Susceptible-Infected-Susceptible model of epidemic spreading on two layers of networks interconnected by adaptive links, which are rewired at random to avoid contacts between infected and susceptible nodes at the interlayer. We find that the rewiring reduces the effective connectivity for the transmission of the disease between layers, and may even totally decouple the networks. Weak endemic states, in which the epidemics spreads when the two layers are interconnected but not in each layer separately, show a transition from the endemic to the healthy phase when the rewiring overcomes a threshold value that depends on the infection rate, the strength of the coupling and the mean connectivity of the networks. In the strong endemic scenario, in which the epidemics is able to spread on each separate network -and therefore on the interconnected system- the prevalence in each layer decreases when increasing the rewiring, arriving to single network values only in the limit of infinitely fast rewiring. We also find that rewiring amplifies finite-size effects, preventing the disease transmission between finite networks, as there is a non zero probability that the epidemics stays confined in only one network during its lifetime.

Rescue of endemic states in interconnected networks with adaptive coupling

PubMed Central

Vazquez, F.; Serrano, M. Ángeles; Miguel, M. San

2016-01-01

We study the Susceptible-Infected-Susceptible model of epidemic spreading on two layers of networks interconnected by adaptive links, which are rewired at random to avoid contacts between infected and susceptible nodes at the interlayer. We find that the rewiring reduces the effective connectivity for the transmission of the disease between layers, and may even totally decouple the networks. Weak endemic states, in which the epidemics spreads when the two layers are interconnected but not in each layer separately, show a transition from the endemic to the healthy phase when the rewiring overcomes a threshold value that depends on the infection rate, the strength of the coupling and the mean connectivity of the networks. In the strong endemic scenario, in which the epidemics is able to spread on each separate network –and therefore on the interconnected system– the prevalence in each layer decreases when increasing the rewiring, arriving to single network values only in the limit of infinitely fast rewiring. We also find that rewiring amplifies finite-size effects, preventing the disease transmission between finite networks, as there is a non zero probability that the epidemics stays confined in only one network during its lifetime. PMID:27380771

Two-loop mass splittings in electroweak multiplets: Winos and minimal dark matter

NASA Astrophysics Data System (ADS)

McKay, James; Scott, Pat

2018-03-01

The radiatively-induced splitting of masses in electroweak multiplets is relevant for both collider phenomenology and dark matter. Precision two-loop corrections of O (MeV ) to the triplet mass splitting in the wino limit of the minimal supersymmetric standard model can affect particle lifetimes by up to 40%. We improve on previous two-loop self-energy calculations for the wino model by obtaining consistent input parameters to the calculation via two-loop renormalization-group running, and including the effect of finite light quark masses. We also present the first two-loop calculation of the mass splitting in an electroweak fermionic quintuplet, corresponding to the viable form of minimal dark matter (MDM). We place significant constraints on the lifetimes of the charged and doubly-charged fermions in this model. We find that the two-loop mass splittings in the MDM quintuplet are not constant in the large-mass limit, as might naively be expected from the triplet calculation. This is due to the influence of the additional heavy fermions in loop corrections to the gauge boson propagators.

Quark and gluon production from a boost-invariantly expanding color electric field

NASA Astrophysics Data System (ADS)

Taya, Hidetoshi

2017-07-01

Particle production from an expanding classical color electromagnetic field is extensively studied, motivated by the early stage dynamics of ultrarelativistic heavy ion collisions. We develop a formalism at one-loop order to compute the particle spectra by canonically quantizing quark, gluon, and ghost fluctuations under the presence of such an expanding classical color background field; the canonical quantization is done in the τ -η coordinates in order to take into account manifestly the expanding geometry. As a demonstration, we model the expanding classical color background field by a boost-invariantly expanding homogeneous color electric field with lifetime T , for which we obtain analytically the quark and gluon production spectra by solving the equations of motion of QCD nonperturbatively with respect to the color electric field. In this paper we study (i) the finite lifetime effect, which is found to modify significantly the particle spectra from those expected from the Schwinger formula; (ii) the difference between the quark and gluon production; and (iii) the quark mass dependence of the production spectra. Implications of these results to ultrarelativistic heavy ion collisions are also discussed.

Discriminating Famous from Fictional Names Based on Lifetime Experience: Evidence in Support of a Signal-Detection Model Based on Finite Mixture Distributions

ERIC Educational Resources Information Center

Bowles, Ben; Harlow, Iain M.; Meeking, Melissa M.; Kohler, Stefan

2012-01-01

It is widely accepted that signal-detection mechanisms contribute to item-recognition memory decisions that involve discriminations between targets and lures based on a controlled laboratory study episode. Here, the authors employed mathematical modeling of receiver operating characteristics (ROC) to determine whether and how a signal-detection…

A Study on the Effects of Ball Defects on the Fatigue Life in Hybrid Bearings

NASA Technical Reports Server (NTRS)

Tang, Ching-Yao; Foerster, Chad E.; O'Brien, Michael J.; Hardy, Brian S.; Goyal, Vinay K.; Nelson, Benjamin A.; Robinson, Ernest Y.; Ward, Peter C.; Hilton, Michael R.

2014-01-01

Hybrid ball bearings using silicon nitride ceramic balls with steel rings are increasingly being used in space mechanism applications due to their high wear resistance and long rolling contact fatigue life. However, qualitative and quantitative reports of the effects of ball defects that cause early fatigue failure are rare. We report on our approach to study these effects. Our strategy includes characterization of defects encountered in use, generation of similar defects in a laboratory setting, execution of full-scale bearing tests to obtain lifetimes, post-test characterization, and related finite-element modeling to understand the stress concentration of these defects. We have confirmed that at least one type of defect of appropriate size can significantly reduce fatigue life. Our method can be used to evaluate other defects as they occur or are encountered.

Disentangling nonradiative recombination processes in Ge micro-crystals on Si substrates

NASA Astrophysics Data System (ADS)

Pezzoli, Fabio; Giorgioni, Anna; Gallacher, Kevin; Isa, Fabio; Biagioni, Paolo; Millar, Ross W.; Gatti, Eleonora; Grilli, Emanuele; Bonera, Emiliano; Isella, Giovanni; Paul, Douglas J.; Miglio, Leo

2016-06-01

We address nonradiative recombination pathways by leveraging surface passivation and dislocation management in μm-scale arrays of Ge crystals grown on deeply patterned Si substrates. The time decay photoluminescence (PL) at cryogenic temperatures discloses carrier lifetimes approaching 45 ns in band-gap engineered Ge micro-crystals. This investigation provides compelling information about the competitive interplay between the radiative band-edge transitions and the trapping of carriers by dislocations and free surfaces. Furthermore, an in-depth analysis of the temperature dependence of the PL, combined with capacitance data and finite difference time domain modeling, demonstrates the effectiveness of GeO2 in passivating the surface of Ge and thus in enhancing the room temperature PL emission.

Simulation of residual stresses and their effects on thermal barrier coating systems using finite element method

NASA Astrophysics Data System (ADS)

Zhu, JianGuo; Chen, Wei; Xie, HuiMin

2015-03-01

Thermal barrier coating (TBC) systems are widely used in industrial gas-turbine engines. However, premature failures have impaired the use of TBCs and cut down their lifetime, which requires a better understanding of their failure mechanisms. In the present study, experimental studies of isothermal cycling are firstly carried out with the observation and estimation of microstructures. According to the experimental results, a finite element model is established for the analysis of stress perpendicular to the TBC/BC interface. Detailed residual stress distributions in TBC are obtained to reflect the influence of mechanical properties, oxidation, and interfacial roughness. The calculated results show that the maximum tensile stress concentration appears at the peak of TBC and continues to increase with thermal cycles. Because of the microstructural characteristics of plasma-sprayed TBCs, cracks initialize in tensile stress concentration (TSC) regions at the peaks of TBC and propagate along the TBC/BC interface resulting in the spallation of TBC. Also, the inclusion of creep is crucial to failure prediction and is more important than the inclusion of sintering in the simulation.

Feasibility of maintaining in-plane polarization for a storage ring EDM search

NASA Astrophysics Data System (ADS)

Stephenson, Edward; Storage Ring EDM Collaboration

2014-09-01

A search for an electric dipole moment (EDM) on charged particles using a storage ring requires beam polarization lifetimes approaching 1000 s for in-plane polarization. A feasibility study using beam bunching and sextupole field adjustment is underway with a 0.97-GeV/c vector-polarized deuteron beam at COSY. The polarimeter consists of a thick carbon target positioned at the edge of the beam and the EDDA scintillation detectors. The DAQ system assigns a clock time to each polarimeter event. Once calibrated against the RF-cavity, the clock time is used to select events associated with a maximal sideways polarization (precessing at 120 kHz). With this tool, the in-plane polarization magnitude is tracked versus time. Electron cooling reduces the depolarization from finite emittance and second-order momentum spread acting through synchrotron oscillations. Further lifetime improvement to the level of hundreds of seconds is achieved by adjusting sextupole fields located in the COSY ring arcs at places of large transverse beta functions and dispersion. The dependence of the reciprocal of the lifetime on sextupole field strength is nearly linear, permitting an easy location of the best field values. These typically occur near loci of zero chromaticity. A search for an electric dipole moment (EDM) on charged particles using a storage ring requires beam polarization lifetimes approaching 1000 s for in-plane polarization. A feasibility study using beam bunching and sextupole field adjustment is underway with a 0.97-GeV/c vector-polarized deuteron beam at COSY. The polarimeter consists of a thick carbon target positioned at the edge of the beam and the EDDA scintillation detectors. The DAQ system assigns a clock time to each polarimeter event. Once calibrated against the RF-cavity, the clock time is used to select events associated with a maximal sideways polarization (precessing at 120 kHz). With this tool, the in-plane polarization magnitude is tracked versus time. Electron cooling reduces the depolarization from finite emittance and second-order momentum spread acting through synchrotron oscillations. Further lifetime improvement to the level of hundreds of seconds is achieved by adjusting sextupole fields located in the COSY ring arcs at places of large transverse beta functions and dispersion. The dependence of the reciprocal of the lifetime on sextupole field strength is nearly linear, permitting an easy location of the best field values. These typically occur near loci of zero chromaticity. Supported in part by the Forschungszentrum-Juelich and the European Union.

Study on Collision of Ship Side Structure by Simplified Plastic Analysis Method

NASA Astrophysics Data System (ADS)

Sun, C. J.; Zhou, J. H.; Wu, W.

2017-10-01

During its lifetime, a ship may encounter collision or grounding and sustain permanent damage after these types of accidents. Crashworthiness has been based on two kinds of main methods: simplified plastic analysis and numerical simulation. A simplified plastic analysis method is presented in this paper. Numerical methods using the non-linear finite-element software LS-DYNA are conducted to validate the method. The results show that, as for the accuracy of calculation results, the simplified plasticity analysis are in good agreement with the finite element simulation, which reveals that the simplified plasticity analysis method can quickly and accurately estimate the crashworthiness of the side structure during the collision process and can be used as a reliable risk assessment method.

A model of irreversible jam formation in dense traffic

NASA Astrophysics Data System (ADS)

Brankov, J. G.; Bunzarova, N. Zh.; Pesheva, N. C.; Priezzhev, V. B.

2018-03-01

We study an one-dimensional stochastic model of vehicular traffic on open segments of a single-lane road of finite size L. The vehicles obey a stochastic discrete-time dynamics which is a limiting case of the generalized Totally Asymmetric Simple Exclusion Process. This dynamics has been previously used by Bunzarova and Pesheva (2017) for an one-dimensional model of irreversible aggregation. The model was shown to have three stationary phases: a many-particle one, MP, a phase with completely filled configuration, CF, and a boundary perturbed MP+CF phase, depending on the values of the particle injection (α), ejection (β) and hopping (p) probabilities. Here we extend the results for the stationary properties of the MP+CF phase, by deriving exact expressions for the local density at the first site of the chain and the probability P(1) of a completely jammed configuration. The unusual phase transition, characterized by jumps in both the bulk density and the current (in the thermodynamic limit), as α crosses the boundary α = p from the MP to the CF phase, is explained by the finite-size behavior of P(1). By using a random walk theory, we find that, when α approaches from below the boundary α = p, three different regimes appear, as the size L → ∞: (i) the lifetime of the gap between the rightmost clusters is of the order O(L) in the MP phase; (ii) small jams, separated by gaps with lifetime O(1) , exist in the MP+CF phase close to the left chain boundary; and (iii) when β = p, the jams are divided by gaps with lifetime of the order O(L 1 / 2) . These results are supported by extensive Monte Carlo calculations.

Studies of silicon p-n junction solar cells

NASA Technical Reports Server (NTRS)

Neugroschel, A.; Lindholm, F. A.

1979-01-01

To provide theoretical support for investigating different ways to obtain high open-circuit voltages in p-n junction silicon solar cells, an analytical treatment of heavily doped transparent-emitter devices is presented that includes the effects of bandgap narrowing, Fermi-Dirac statistics, a doping concentration gradient, and a finite surface recombination velocity at the emitter surface. Topics covered include: (1) experimental determination of bandgap narrowing in the emitter of silicon p-n junction devices; (2) heavily doped transparent regions in junction solar cells, diodes, and transistors; (3) high-low-emitter solar cell; (4) determination of lifetimes and recombination currents in p-n junction solar cells; (5) MOS and oxide-charged-induced BSF solar cells; and (6) design of high efficiency solar cells for space and terrestrial applications.

Intermittency in two-dimensional Ekman-Navier-Stokes turbulence.

PubMed

Boffetta, G; Celani, A; Musacchio, S; Vergassola, M

2002-08-01

We study the statistics of the vorticity field in two-dimensional Navier-Stokes turbulence with linear Ekman friction. We show that the small-scale vorticity fluctuations are intermittent, as conjectured by Bernard [Europhys. Lett. 50, 333 (2000)] and Nam et al. [Phys. Rev. Lett. 84, 5134 (2000)]. The small-scale statistics of vorticity fluctuations coincide with that of a passive scalar with finite lifetime transported by the velocity field itself.

Stress and efficiency studies in EFG

NASA Technical Reports Server (NTRS)

1986-01-01

The goals of this program were: (1) to define minimum stress configurations for silicon sheet growth at high speeds; (2) to quantify dislocation electrical activity and their limits on minority carrier diffusion length in deformed silicon; and (3) to study reasons for degradation of lifetime with increases in doping level in edge-defined film-fed growth (EFG) materials. A finite element model was developed for calculating residual stress with plastic deformation. A finite element model was verified for EFG control variable relationships to temperature field of the sheet to permit prediction of profiles and stresses encountered in EFG systems. A residual stress measurement technique was developed for finite size EFG material blanks using shadow Moire interferometry. Transient creep response of silicon was investigated in the temperature range between 800 and 1400 C in strain and strain regimes of interest in stress analysis of sheet growth. Quantitative relationships were established between minority carrier diffusion length and dislocation densities using Electron Beam Induced Current (EBIC) measurement in FZ silicon deformed in four point bending tests.

Shear viscosity of a hadron gas and influence of resonance lifetimes on relaxation time

NASA Astrophysics Data System (ADS)

Rose, J.-B.; Torres-Rincon, J. M.; Schäfer, A.; Oliinychenko, D. R.; Petersen, H.

2018-05-01

We address a discrepancy between different computations of η /s (shear viscosity over entropy density) of hadronic matter. Substantial deviations of this coefficient are found between transport approaches mainly based on resonance propagation with finite lifetime and other (semianalytical) approaches with energy-dependent cross sections, where interactions do not introduce a timescale. We provide an independent extraction of this coefficient by using the newly developed SMASH (Simulating Many Accelerated Strongly interacting Hadrons) transport code, which is an example of a mainly resonance-based approach. We compare the results from SMASH with numerical solutions of the Boltzmann equation for simple systems using the Chapman-Enskog expansion, as well as previous results in the literature. Our conclusion is that the hadron interaction via resonance formation/decay strongly affects the transport properties of the system, resulting in significant differences in η /s with respect to other approaches where binary collisions dominate. We argue that the relaxation time of the system—which characterizes the shear viscosity—is determined by the interplay between the mean free time and the lifetime of resonances. We show how an artificial shortening of the resonance lifetimes, or the addition of a background elastic cross section nicely interpolate between the two discrepant results.

Investigation of Singly Ionized Iodine Spectroscopy in Support of Electrostatic Propulsion Diagnostics Development

DTIC Science & Technology

2012-07-02

from complex user interactions due to the use of liquid lasing medium with finite lifetime. Solid state lasers such as titanium sapphire (Ti:Sapphire...transitions for laser -induced fluorescence of an accelerated atomic iodine singly charged ion (I+). While the second spectrum of iodine has been analyzed...diagnostics tools, such as laser -induced fluorescence (LIF), to examine the plasma acceleration within an electro-static plasma propulsion thruster. While

Numerical Studies of Three-dimensional Breakdown in Trailing Vortex Wakes

NASA Technical Reports Server (NTRS)

Evans, P. F.; Hackett, J. E.

1976-01-01

Finite element, three dimensional relaxation methods are used to calculate the development of vortex wakes behind aircraft for a considerable downstream distance. The inclusion of a self-induction term in the solution, dependent upon local curvature and vortex core radius, permits calculation of finite lifetimes for systems for which infinite life would be predicted two dimensionally. The associated computer program is described together with single-pair, twin-pair, and multiple-pair studies carried out using it. It is found, in single-pair studies, that there is a lower limit to the wavelengths at which the Crow-type of instability can occur. Below this limit, self-induction effects cause the plane of the disturbance waves to rotate counter to the vortex direction. Self induction in two dimensionally generated twin spiral waves causes an increase in axial length which becomes more marked with decreasing initial wavelength. The time taken for vortex convergence toward the center plane is correspondingly increased. The limited parametric twin-pair study performed suggests that time-to-converge increases with increasing flap span. Limited studies of Boeing 747 configurations show correct qualitative response to removal of the outer flap and to gear deployment, as compared with wind tunnel and flight test experience.

The Sacred Mountain of Varallo in Italy: seismic risk assessment by acoustic emission and structural numerical models.

PubMed

Carpinteri, Alberto; Lacidogna, Giuseppe; Invernizzi, Stefano; Accornero, Federico

2013-01-01

We examine an application of Acoustic Emission (AE) technique for a probabilistic analysis in time and space of earthquakes, in order to preserve the valuable Italian Renaissance Architectural Complex named "The Sacred Mountain of Varallo." Among the forty-five chapels of the Renaissance Complex, the structure of the Chapel XVII is of particular concern due to its uncertain structural condition and due to the level of stress caused by the regional seismicity. Therefore, lifetime assessment, taking into account the evolution of damage phenomena, is necessary to preserve the reliability and safety of this masterpiece of cultural heritage. A continuous AE monitoring was performed to assess the structural behavior of the Chapel. During the monitoring period, a correlation between peaks of AE activity in the masonry of the "Sacred Mountain of Varallo" and regional seismicity was found. Although the two phenomena take place on very different scales, the AE in materials and the earthquakes in Earth's crust, belong to the same class of invariance. In addition, an accurate finite element model, performed with DIANA finite element code, is presented to describe the dynamic behavior of Chapel XVII structure, confirming visual and instrumental inspections of regional seismic effects.

The effect of coupled transport phenomena in the Opalinus Clay and implications for radionuclide transport

NASA Astrophysics Data System (ADS)

Soler, Josep M.

2001-12-01

In this study, the potential effects of coupled transport phenomena on radionuclide transport in the vicinity of a repository for vitrified high-level radioactive waste (HLW) and spent nuclear fuel (SF) hosted by the Opalinus Clay in Switzerland, at times equal to or greater than the expected lifetime of the waste canisters (about 1000 years), are addressed. The solute fluxes associated with advection, chemical diffusion, thermal and chemical osmosis, hyperfiltration and thermal diffusion have been incorporated into a simple one-dimensional transport equation. The analytical solution of this equation, with appropriate parameters, shows that thermal osmosis is the only coupled transport mechanism that could, on its own, have a strong effect on repository performance. Based on the results from the analytical model, two-dimensional finite-difference models incorporating advection and thermal osmosis, and taking conservation of fluid mass into account, have been formulated. The results show that, under the conditions in the vicinity of the repository at the time scales of interest, and due to the constraints imposed by conservation of fluid mass, the advective component of flow will oppose and cancel the thermal-osmotic component. The overall conclusion is that coupled phenomena will only have a very minor impact on radionuclide transport in the Opalinus Clay, in terms of fluid and solute fluxes, at least under the conditions prevailing at times equal to or greater than the expected lifetime of the waste canisters (about 1000 years).

Purcell effect in triangular plasmonic nanopatch antennas with three-layer colloidal quantum dots

NASA Astrophysics Data System (ADS)

Eliseev, S. P.; Kurochkin, N. S.; Vergeles, S. S.; Sychev, V. V.; Chubich, D. A.; Argyrakis, P.; Kolymagin, D. A.; Vitukhnovskii, A. G.

2017-05-01

A model describing a plasmonic nanopatch antenna based on triangular silver nanoprisms and multilayer cadmium chalcogenide quantum dots is introduced. Electromagnetic-field distributions in nanopatch antennas with different orientations of the quantum-dot dipoles are calculated for the first time with the finite element method for numerical electrodynamics simulations. The energy flux through the surface of an emitting quantum dot is calculated for the configurations with the dot in free space, on an aluminum substrate, and in a nanopatch antenna. It is shown that the radiative part of the Purcell factor is as large as 1.7 × 102 The calculated photoluminescence lifetimes of a CdSe/CdS/ZnS colloidal quantum dot in a nanopatch antenna based on a silver nanoprism agree well with the experimental results.

Laser-induced electron dynamics including photoionization: A heuristic model within time-dependent configuration interaction theory.

PubMed

Klinkusch, Stefan; Saalfrank, Peter; Klamroth, Tillmann

2009-09-21

We report simulations of laser-pulse driven many-electron dynamics by means of a simple, heuristic extension of the time-dependent configuration interaction singles (TD-CIS) approach. The extension allows for the treatment of ionizing states as nonstationary states with a finite, energy-dependent lifetime to account for above-threshold ionization losses in laser-driven many-electron dynamics. The extended TD-CIS method is applied to the following specific examples: (i) state-to-state transitions in the LiCN molecule which correspond to intramolecular charge transfer, (ii) creation of electronic wave packets in LiCN including wave packet analysis by pump-probe spectroscopy, and, finally, (iii) the effect of ionization on the dynamic polarizability of H(2) when calculated nonperturbatively by TD-CIS.

DOUBLE POWER LAWS IN THE EVENT-INTEGRATED SOLAR ENERGETIC PARTICLE SPECTRUM

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

Zhao, Lulu; Zhang, Ming; Rassoul, Hamid K., E-mail: lzhao@fit.edu

2016-04-10

A double power law or a power law with exponential rollover at a few to tens of MeV nucleon{sup −1} of the event-integrated differential spectra has been reported in many solar energetic particle (SEP) events. The rollover energies per nucleon of different elements correlate with a particle's charge-to-mass ratio (Q/A). The probable causes are suggested as residing in shock finite lifetimes, shock finite sizes, shock geometry, and an adiabatic cooling effect. In this work, we conduct a numerical simulation to investigate a particle's transport process in the inner heliosphere. We solve the focused transport equation using a time-backward Markov stochasticmore » approach. The convection, magnetic focusing, adiabatic cooling effect, and pitch-angle scattering are included. The effects that the interplanetary turbulence imposes on the shape of the resulting SEP spectra are examined. By assuming a pure power-law differential spectrum at the Sun, a perfect double-power-law feature with a break energy ranging from 10 to 120 MeV nucleon{sup −1} is obtained at 1 au. We found that the double power law of the differential energy spectrum is a robust result of SEP interplanetary propagation. It works for many assumptions of interplanetary turbulence spectra that give various forms of momentum dependence of a particle's mean free path. The different spectral shapes in low-energy and high-energy ends are not just a transition from the convection-dominated propagation to diffusion-dominated propagation.« less

Non-stationary and relaxation phenomena in cavity-assisted quantum memories

NASA Astrophysics Data System (ADS)

Veselkova, N. G.; Sokolov, I. V.

2017-12-01

We investigate the non-stationary and relaxation phenomena in cavity-assisted quantum memories for light. As a storage medium we consider an ensemble of cold atoms with standard Lambda-scheme of working levels. Some theoretical aspects of the problem were treated previously by many authors, and recent experiments stimulate more deep insight into the ultimate ability and limitations of the device. Since quantum memories can be used not only for the storage of quantum information, but also for a substantial manipulation of ensembles of quantum states, the speed of such manipulation and hence the ability to write and retrieve the signals of relatively short duration becomes important. In our research we do not apply the so-called bad cavity limit, and consider the memory operation of the signals whose duration is not much larger than the cavity field lifetime, accounting also for the finite lifetime of atomic coherence. In our paper we present an effective approach that makes it possible to find the non-stationary amplitude and phase behavior of strong classical control field, that matches the desirable time profile of both the envelope and the phase of the retrieved quantized signal. The phase properties of the retrieved quantized signals are of importance for the detection and manipulation of squeezing, entanglement, etc by means of optical mixing and homodyning.

The Influence of Planetary Mass on the Dynamical Lifetime of Planetary Systems

NASA Technical Reports Server (NTRS)

Lissauer, J. J.; Duncan, M. J.; Young, Richard E. (Technical Monitor)

1997-01-01

Recent numerical and analytic studies of planetary orbits have demonstrated the importance of resonances and chaos in destabilizing planetary systems. Newton's "clockwork" description of regular, predictable planetary orbits has been replaced by a view in which many systems can have long but finite lifetimes. This new knowledge has altered our perceptions of the later stages of planetary growth and of the stability of planetary systems. Stability criteria are inexact and time dependent. Most previous studies have focused on the effects in initial planetary orbits on the stability of the system. We are conducting an investigation which focuses on the dependence of stability criteria on planetary mass. Synthetic systems are created by increasing the masses of the planets in our Solar System or of the moons of a particular planet; these systems are then integrated until orbit crossing occurs. We have found that over some ranges, the time until orbit crossing varies to a good approximation as a power clothe factor by which the masses of the secondaries arc increased; some scatter occurs as a consequence of vie chaotic nature of orbital evolution. The slope of this power law varies substantially from system to system, and for moons it is mildly dependent on the inclusion of the planet's quadrupole moment in the gravitational potential.

The case for mixed dark matter from sterile neutrinos

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

Lello, Louis; Boyanovsky, Daniel, E-mail: lal81@pitt.edu, E-mail: boyan@pitt.edu

2016-06-01

Sterile neutrinos are SU(2) singlets that mix with active neutrinos via a mass matrix, its diagonalization leads to mass eigenstates that couple via standard model vertices. We study the cosmological production of heavy neutrinos via standard model charged and neutral current vertices under a minimal set of assumptions: i) the mass basis contains a hierarchy of heavy neutrinos , ii) these have very small mixing angles with the active (flavor) neutrinos, iii) standard model particles, including light (active-like) neutrinos are in thermal equilibrium. If kinematically allowed, the same weak interaction processes that produce active-like neutrinos also produce the heavier species.more » We introduce the quantum kinetic equations that describe their production, freeze out and decay and discuss the various processes that lead to their production in a wide range of temperatures assessing their feasibility as dark matter candidates. The final distribution function at freeze-out is a mixture of the result of the various production processes. We identify processes in which finite temperature collective excitations may lead to the production of the heavy species. As a specific example, we consider the production of heavy neutrinos in the mass range M {sub h} ∼< 140 MeV from pion decay shortly after the QCD crossover including finite temperature corrections to the pion form factors and mass. We consider the different decay channels that allow for the production of heavy neutrinos showing that their frozen distribution functions exhibit effects from ''kinematic entanglement'' and argue for their viability as mixed dark matter candidates. We discuss abundance, phase space density and stability constraints and argue that heavy neutrinos with lifetime τ> 1/ H {sub 0} freeze out of local thermal equilibrium, and conjecture that those with lifetimes τ || 1/ H {sub 0} may undergo cascade decay into lighter DM candidates and/or inject non-LTE neutrinos into the cosmic neutrino background. We provide a comparison with non-resonant production via active-sterile mixing.« less

Evolution of entanglement between distinguishable light states.

PubMed

Stevenson, R Mark; Hudson, Andrew J; Bennett, Anthony J; Young, Robert J; Nicoll, Christine A; Ritchie, David A; Shields, Andrew J

2008-10-24

We investigate the evolution of quantum correlations over the lifetime of a multiphoton state. Measurements reveal time-dependent oscillations of the entanglement fidelity for photon pairs created by a single semiconductor quantum dot. The oscillations are attributed to the phase acquired in the intermediate, nondegenerate, exciton-photon state and are consistent with simulations. We conclude that emission of photon pairs by a typical quantum dot with finite polarization splitting is in fact entangled in a time-evolving state, and not classically correlated as previously regarded.

Anthropic versus cosmological solutions to the coincidence problem

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

Barreira, A.; Avelino, P. P.; Departamento de Fisica da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto

2011-05-15

In this paper, we investigate possible solutions to the coincidence problem in flat phantom dark-energy models with a constant dark-energy equation of state and quintessence models with a linear scalar field potential. These models are representative of a broader class of cosmological scenarios in which the universe has a finite lifetime. We show that, in the absence of anthropic constraints, including a prior probability for the models inversely proportional to the total lifetime of the universe excludes models very close to the {Lambda} cold dark matter model. This relates a cosmological solution to the coincidence problem with a dynamical dark-energymore » component having an equation-of-state parameter not too close to -1 at the present time. We further show that anthropic constraints, if they are sufficiently stringent, may solve the coincidence problem without the need for dynamical dark energy.« less

Thick-target bremsstrahlung interpretation of short time-scale solar hard X-ray features

NASA Technical Reports Server (NTRS)

Emslie, A. G.

1983-01-01

Steady-state analyses of bremsstrahlung hard X-ray production in solar flares are appropriate only if the lifetime of the high energy electrons in the X-ray source is much shorter than the duration of the observed X-ray burst. For a thick-target nonthermal model, this implies that a full time-dependent analysis is required when the duration of the burst is comparable to the collisional lifetime of the injected electrons, in turn set by the lengths and densities of the flaring region. In this paper we present the results of such a time-dependent analysis, and we point out that the intrinsic temporal signature of the thick-target production mechanism, caused by the finite travel time of the electrons through the target, may indeed rule out such a mechanism for extremely short duration hard X-ray events.

Study of the key factors affecting the triple grid lifetime of the LIPS-300 ion thruster

NASA Astrophysics Data System (ADS)

Mingming, SUN; Liang, WANG; Juntai, YANG; Xiaodong, WEN; Yongjie, HUANG; Meng, WANG

2018-04-01

In order to ascertain the key factors affecting the lifetime of the triple grids in the LIPS-300 ion thruster, the thermal deformation, upstream ion density and component lifetime of the grids are simulated with finite element analysis, fluid simulation and charged-particle tracing simulation methods on the basis of a 1500 h short lifetime test. The key factor affecting the lifetime of the triple grids in the LIPS-300 ion thruster is obtained and analyzed through the test results. The results show that ion sputtering erosion of the grids in 5 kW operation mode is greater than in the case of 3 kW. In 5 kW mode, the decelerator grid shows the most serious corrosion, the accelerator grid shows moderate corrosion, and the screen grid shows the least amount of corrosion. With the serious corrosion of the grids in 5 kW operation mode, the intercept current of the acceleration and deceleration grids increases substantially. Meanwhile, the cold gap between the accelerator grid and the screen grid decreases from 1 mm to 0.7 mm, while the cold gap between the accelerator grid and the decelerator grid increases from 1 mm to 1.25 mm after 1500 h of thruster operation. At equilibrium temperature with 5 kW power, the finite element method (FEM) simulation results show that the hot gap between the screen grid and the accelerator grid reduces to 0.2 mm. Accordingly, the hot gap between the accelerator grid and the decelerator grid increases to 1.5 mm. According to the fluid method, the plasma density simulated in most regions of the discharge chamber is 1 × 1018‑8 × 1018 m‑3. The upstream plasma density of the screen grid is in the range 6 × 1017‑6 × 1018 m‑3 and displays a parabolic characteristic. The charged particle tracing simulation method results show that the ion beam current without the thermal deformation of triple grids has optimal perveance status. The ion sputtering rates of the accelerator grid hole and the decelerator hole are 5.5 × 10‑14 kg s‑1 and 4.28 × 10‑14 kg s‑1, respectively, while after the thermal deformation of the triple grids, the ion beam current has over-perveance status. The ion sputtering rates of the accelerator grid hole and the decelerator hole are 1.41 × 10‑13 kg s‑1 and 4.1 × 10‑13 kg s‑1, respectively. The anode current is a key factor for the triple grid lifetime in situations where the structural strength of the grids does not change with temperature variation. The average sputtering rates of the accelerator grid and the decelerator grid, which were measured during the 1500 h lifetime test in 5 kW operating conditions, are 2.2 × 10‑13 kg s‑1 and 7.3 × 10‑13 kg s‑1, respectively. These results are in accordance with the simulation, and the error comes mainly from the calculation distribution of the upstream plasma density of the grids.

Charge-Dependent Directed Flow in Cu +Au Collisions at √{sN N } =200 GeV

NASA Astrophysics Data System (ADS)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Anderson, D. M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Esumi, S.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, B.; Huang, X.; Huang, H. Z.; Huang, T.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jentsch, A.; Jia, J.; Jiang, K.; Jowzaee, S.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, Y.; Li, C.; Li, W.; Li, X.; Li, X.; Lin, T.; Lisa, M. A.; Liu, Y.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Luo, S.; Ma, G. L.; Ma, R.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Miller, Z. W.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Nonaka, T.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Ray, R. L.; Reed, R.; Rehbein, M. J.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roth, J. D.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, M. K.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shi, Z.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sugiura, T.; Sumbera, M.; Summa, B.; Sun, Z.; Sun, Y.; Sun, X. M.; Surrow, B.; Svirida, D. N.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, G.; Wang, F.; Wang, J. S.; Wang, Y.; Wang, H.; Wang, Y.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, Q. H.; Xu, Y. F.; Xu, H.; Xu, Z.; Xu, N.; Xu, J.; Yang, C.; Yang, Y.; Yang, S.; Yang, Y.; Yang, Q.; Yang, Y.; Ye, Z.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.; Zhang, X. P.; Zhang, S.; Zhang, Y.; Zhang, J. B.; Zhang, Z.; Zhang, S.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

2017-01-01

We present the first measurement of charge-dependent directed flow in Cu +Au collisions at √{sN N }=200 GeV . The results are presented as a function of the particle transverse momentum and pseudorapidity for different centralities. A finite difference between the directed flow of positive and negative charged particles is observed that qualitatively agrees with the expectations from the effects of the initial strong electric field between two colliding ions with different nuclear charges. The measured difference in directed flow is much smaller than that obtained from the parton-hadron-string-dynamics model, which suggests that most of the electric charges, i.e., quarks and antiquarks, have not yet been created during the lifetime of the strong electric field, which is of the order of, or less than, 1 fm /c .

Broadband enhancement of single photon emission and polarization dependent coupling in silicon nitride waveguides.

PubMed

Bisschop, Suzanne; Guille, Antoine; Van Thourhout, Dries; Hens, Zeger; Brainis, Edouard

2015-06-01

Single-photon (SP) sources are important for a number of optical quantum information processing applications. We study the possibility to integrate triggered solid-state SP emitters directly on a photonic chip. A major challenge consists in efficiently extracting their emission into a single guided mode. Using 3D finite-difference time-domain simulations, we investigate the SP emission from dipole-like nanometer-sized inclusions embedded into different silicon nitride (SiNx) photonic nanowire waveguide designs. We elucidate the effect of the geometry on the emission lifetime and the polarization of the emitted SP. The results show that highly efficient and polarized SP sources can be realized using suspended SiNx slot-waveguides. Combining this with the well-established CMOS-compatible processing technology, fully integrated and complex optical circuits for quantum optics experiments can be developed.

Scale-invariant instantons and the complete lifetime of the standard model

NASA Astrophysics Data System (ADS)

Andreassen, Anders; Frost, William; Schwartz, Matthew D.

2018-03-01

In a classically scale-invariant quantum field theory, tunneling rates are infrared divergent due to the existence of instantons of any size. While one expects such divergences to be resolved by quantum effects, it has been unclear how higher-loop corrections can resolve a problem appearing already at one loop. With a careful power counting, we uncover a series of loop contributions that dominate over the one-loop result and sum all the necessary terms. We also clarify previously incomplete treatments of related issues pertaining to global symmetries, gauge fixing, and finite mass effects. In addition, we produce exact closed-form solutions for the functional determinants over scalars, fermions, and vector bosons around the scale-invariant bounce, demonstrating manifest gauge invariance in the vector case. With these problems solved, we produce the first complete calculation of the lifetime of our Universe: 1 0139 years . With 95% confidence, we expect our Universe to last more than 1 058 years . The uncertainty is part experimental uncertainty on the top quark mass and on αs and part theory uncertainty from electroweak threshold corrections. Using our complete result, we provide phase diagrams in the mt/mh and the mt/αs planes, with uncertainty bands. To rule out absolute stability to 3 σ confidence, the uncertainty on the top quark pole mass would have to be pushed below 250 MeV or the uncertainty on αs(mZ) pushed below 0.00025.

The Sacred Mountain of Varallo in Italy: Seismic Risk Assessment by Acoustic Emission and Structural Numerical Models

PubMed Central

Carpinteri, Alberto; Invernizzi, Stefano; Accornero, Federico

2013-01-01

We examine an application of Acoustic Emission (AE) technique for a probabilistic analysis in time and space of earthquakes, in order to preserve the valuable Italian Renaissance Architectural Complex named “The Sacred Mountain of Varallo.” Among the forty-five chapels of the Renaissance Complex, the structure of the Chapel XVII is of particular concern due to its uncertain structural condition and due to the level of stress caused by the regional seismicity. Therefore, lifetime assessment, taking into account the evolution of damage phenomena, is necessary to preserve the reliability and safety of this masterpiece of cultural heritage. A continuous AE monitoring was performed to assess the structural behavior of the Chapel. During the monitoring period, a correlation between peaks of AE activity in the masonry of the “Sacred Mountain of Varallo” and regional seismicity was found. Although the two phenomena take place on very different scales, the AE in materials and the earthquakes in Earth's crust, belong to the same class of invariance. In addition, an accurate finite element model, performed with DIANA finite element code, is presented to describe the dynamic behavior of Chapel XVII structure, confirming visual and instrumental inspections of regional seismic effects. PMID:24381511

Optimizing thickness of ceramic coatings on plastic components for orthopedic applications: A finite element analysis.

PubMed

Marchiori, G; Lopomo, N; Boi, M; Berni, M; Bianchi, M; Gambardella, A; Visani, A; Russo, A; Marcacci, M

2016-01-01

Realizing hard ceramic coatings on the plastic component of a joint prosthesis can be strategic for the mechanical preservation of the whole implant and to extend its lifetime. Recently, thanks to the Plasma Pulsed Deposition (PPD) method, zirconia coatings on ultra-high molecular weight polyethylene (UHMWPE) substrates resulted in a feasible outcome. Focusing on both the highly specific requirements defined by the biomedical application and the effective possibilities given by the deposition method in the perspectives of technological transfer, it is mandatory to optimize the coating in terms of load bearing capacity. The main goal of this study was to identify through Finite Element Analysis (FEA) the optimal coating thickness that would be able to minimize UHMWPE strain, possible insurgence of cracks within the coating and stresses at coating-substrate interface. Simulations of nanoindentation and microindentation tests were specifically carried out. FEA findings demonstrated that, in general, thickening the zirconia coating strongly reduced the strains in the UHMWPE substrate, although the 1 μm thickness value was identified as critical for the presence of high stresses within the coating and at the interface with the substrate. Therefore, the optimal thickness resulted to be highly dependent on the specific loading condition and final applications. Copyright © 2015 Elsevier B.V. All rights reserved.

A qubit coupled with confined phonons: The interplay between true and fake decoherence

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

Pouthier, Vincent

2013-08-07

The decoherence of a qubit coupled with the phonons of a finite-size lattice is investigated. The confined phonons no longer behave as a reservoir. They remain sensitive to the qubit so that the origin of the decoherence is twofold. First, a qubit-phonon entanglement yields an incomplete true decoherence. Second, the qubit renormalizes the phonon frequency resulting in fake decoherence when a thermal average is performed. To account for the initial thermalization of the lattice, the qua- ntum Langevin theory is applied so that the phonons are viewed as an open system coupled with a thermal bath of harmonic oscillators. Consequently,more » it is shown that the finite lifetime of the phonons does not modify fake decoherence but strongly affects true decoherence. Depending on the values of the model parameters, the interplay between fake and true decoherence yields a very rich dynamics with various regimes.« less

Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging

NASA Astrophysics Data System (ADS)

Yankelevich, Diego R.; Ma, Dinglong; Liu, Jing; Sun, Yang; Sun, Yinghua; Bec, Julien; Elson, Daniel S.; Marcu, Laura

2014-03-01

The application of time-resolved fluorescence spectroscopy (TRFS) to in vivo tissue diagnosis requires a method for fast acquisition of fluorescence decay profiles in multiple spectral bands. This study focusses on development of a clinically compatible fiber-optic based multispectral TRFS (ms-TRFS) system together with validation of its accuracy and precision for fluorescence lifetime measurements. It also presents the expansion of this technique into an imaging spectroscopy method. A tandem array of dichroic beamsplitters and filters was used to record TRFS decay profiles at four distinct spectral bands where biological tissue typically presents fluorescence emission maxima, namely, 390, 452, 542, and 629 nm. Each emission channel was temporally separated by using transmission delays through 200 μm diameter multimode optical fibers of 1, 10, 19, and 28 m lengths. A Laguerre-expansion deconvolution algorithm was used to compensate for modal dispersion inherent to large diameter optical fibers and the finite bandwidth of detectors and digitizers. The system was found to be highly efficient and fast requiring a few nano-Joule of laser pulse energy and <1 ms per point measurement, respectively, for the detection of tissue autofluorescent components. Organic and biological chromophores with lifetimes that spanned a 0.8-7 ns range were used for system validation, and the measured lifetimes from the organic fluorophores deviated by less than 10% from values reported in the literature. Multi-spectral lifetime images of organic dye solutions contained in glass capillary tubes were recorded by raster scanning the single fiber probe in a 2D plane to validate the system as an imaging tool. The lifetime measurement variability was measured indicating that the system provides reproducible results with a standard deviation smaller than 50 ps. The ms-TRFS is a compact apparatus that makes possible the fast, accurate, and precise multispectral time-resolved fluorescence lifetime measurements of low quantum efficiency sub-nanosecond fluorophores.

Photovoltaic cells for laser power beaming

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Jain, Raj K.

1992-01-01

To better understand cell response to pulsed illumination at high intensity, the PC-1DC finite-element computer model was used to analyze the response of solar cells to pulsed laser illumination. Over 50% efficiency was calculated for both InP and GaAs cells under steady-state illumination near the optimum wavelength. The time-dependent response of a high-efficiency GaAs concentrator cell to a laser pulse was modelled, and the effect of laser intensity, wavelength, and bias point was studied. Designing a cell to accommodate pulsed input can be done either by accepting the pulsed output and designing a cell to minimize adverse effects due to series resistance and inductance, or to design a cell with a long enough minority carrier lifetime, so that the output of the cell will not follow the pulse shape. Two such design possibilities are a monolithic, low-inductance voltage-adding GaAs cell, or a high-efficiency, light-trapping silicon cell. The advantages of each design will be discussed.

Scaling properties of a rice-pile model: inertia and friction effects.

PubMed

Khfifi, M; Loulidi, M

2008-11-01

We present a rice-pile cellular automaton model that includes inertial and friction effects. This model is studied in one dimension, where the updating of metastable sites is done according to a stochastic dynamics governed by a probabilistic toppling parameter p that depends on the accumulated energy of moving grains. We investigate the scaling properties of the model using finite-size scaling analysis. The avalanche size, the lifetime, and the residence time distributions exhibit a power-law behavior. Their corresponding critical exponents, respectively, tau, y, and yr, are not universal. They present continuous variation versus the parameters of the system. The maximal value of the critical exponent tau that our model gives is very close to the experimental one, tau=2.02 [Frette, Nature (London) 379, 49 (1996)], and the probability distribution of the residence time is in good agreement with the experimental results. We note that the critical behavior is observed only in a certain range of parameter values of the system which correspond to low inertia and high friction.

Mediating role of borderline personality disorder traits in the effects of childhood maltreatment on suicidal behaviour among mood disorder patients.

PubMed

Aaltonen, K I; Rosenström, T; Baryshnikov, I; Karpov, B; Melartin, T; Suominen, K; Heikkinen, M; Näätänen, P; Koivisto, M; Joffe, G; Isometsä, E

2017-07-01

Substantial evidence supports an association between childhood maltreatment and suicidal behaviour. However, few studies have examined factors mediating this relationship among patients with unipolar or bipolar mood disorders. Depressive disorder and bipolar disorder (ICD-10-DCR) patients (n=287) from the Helsinki University Psychiatric Consortium (HUPC) Study were surveyed on self-reported childhood experiences, current depressive symptoms, borderline personality disorder traits, and lifetime suicidal behaviour. Psychiatric records served to complement the information on suicide attempts. We examined by formal mediation analyses whether (1) the effect of childhood maltreatment on suicidal behaviour is mediated through borderline personality disorder traits and (2) the mediation effect differs between lifetime suicidal ideation and lifetime suicide attempts. The impact of childhood maltreatment in multivariate models on either lifetime suicidal ideation or lifetime suicide attempts showed comparable total effects. In formal mediation analyses, borderline personality disorder traits mediated all of the total effect of childhood maltreatment on lifetime suicide attempts, but only one fifth of the total effect on lifetime suicidal ideation. The mediation effect was stronger for lifetime suicide attempts than for lifetime suicidal ideation (P=0.002) and independent of current depressive symptoms. The mechanisms of the effect of childhood maltreatment on suicidal ideation versus suicide attempts may diverge among psychiatric patients with mood disorders. Borderline personality disorder traits may contribute to these mechanisms, although the influence appears considerably stronger for suicide attempts than for suicidal ideation. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Structural flexibility of the sulfur mustard molecule at finite temperature from Car-Parrinello molecular dynamics simulations.

PubMed

Lach, Joanna; Goclon, Jakub; Rodziewicz, Pawel

2016-04-05

Sulfur mustard (SM) is one of the most dangerous chemical compounds used against humans, mostly at war conditions but also in terrorist attacks. Even though the sulfur mustard has been synthesized over a hundred years ago, some of its molecular properties are not yet resolved. We investigate the structural flexibility of the SM molecule in the gas phase by Car-Parrinello molecular dynamics simulations. Thorough conformation analysis of 81 different SM configurations using density functional theory is performed to analyze the behavior of the system at finite temperature. The conformational diversity is analyzed with respect to the formation of intramolecular blue-shifting CH⋯S and CH⋯Cl hydrogen bonds. Molecular dynamics simulations indicate that all structural rearrangements between SM local minima are realized either in direct or non-direct way, including the intermediate structure in the last case. We study the lifetime of the SM conformers and perform the population analysis. Additionally, we provide the anharmonic dynamical finite temperature IR spectrum from the Fourier Transform of the dipole moment autocorrelation function to mimic the missing experimental IR spectrum. Copyright © 2015 Elsevier B.V. All rights reserved.

Computation of Molecular Spectra on a Quantum Processor with an Error-Resilient Algorithm

DOE PAGES

Colless, J. I.; Ramasesh, V. V.; Dahlen, D.; ...

2018-02-12

Harnessing the full power of nascent quantum processors requires the efficient management of a limited number of quantum bits with finite coherent lifetimes. Hybrid algorithms, such as the variational quantum eigensolver (VQE), leverage classical resources to reduce the required number of quantum gates. Experimental demonstrations of VQE have resulted in calculation of Hamiltonian ground states, and a new theoretical approach based on a quantum subspace expansion (QSE) has outlined a procedure for determining excited states that are central to dynamical processes. Here, we use a superconducting-qubit-based processor to apply the QSE approach to the H 2 molecule, extracting both groundmore » and excited states without the need for auxiliary qubits or additional minimization. Further, we show that this extended protocol can mitigate the effects of incoherent errors, potentially enabling larger-scale quantum simulations without the need for complex error-correction techniques.« less

Modeling of LWIR HgCdTe Auger-Suppressed Infrared Photodiodes under Nonequilibrium Operation

NASA Astrophysics Data System (ADS)

Emelie, P. Y.; Velicu, S.; Grein, C. H.; Phillips, J. D.; Wijewarnasuriya, P. S.; Dhar, N. K.

2008-09-01

The general approach and effects of nonequilibrium operation of Auger-suppressed HgCdTe infrared photodiodes are well understood. However, the complex relationships of carrier generation and dependencies on nonuniform carrier profiles in the device prevent the development of simplistic analytical device models with acceptable accuracy. In this work, finite element methods are used to obtain self-consistent steady-state solutions of Poisson’s equation and the carrier continuity equations. Experimental current-voltage characteristics between 120 K and 300 K of HgCdTe Auger-suppressed photodiodes with cutoff wavelength of λ c = 10 μm at 120 K are fitted using our numerical model. Based on this fitting, we study the lifetime in the absorber region, extract the current mechanisms limiting the dark current in these photodiodes, and discuss design and fabrication considerations in order to optimize future HgCdTe Auger-suppressed photodiodes.

Computation of Molecular Spectra on a Quantum Processor with an Error-Resilient Algorithm

NASA Astrophysics Data System (ADS)

Colless, J. I.; Ramasesh, V. V.; Dahlen, D.; Blok, M. S.; Kimchi-Schwartz, M. E.; McClean, J. R.; Carter, J.; de Jong, W. A.; Siddiqi, I.

2018-02-01

Harnessing the full power of nascent quantum processors requires the efficient management of a limited number of quantum bits with finite coherent lifetimes. Hybrid algorithms, such as the variational quantum eigensolver (VQE), leverage classical resources to reduce the required number of quantum gates. Experimental demonstrations of VQE have resulted in calculation of Hamiltonian ground states, and a new theoretical approach based on a quantum subspace expansion (QSE) has outlined a procedure for determining excited states that are central to dynamical processes. We use a superconducting-qubit-based processor to apply the QSE approach to the H2 molecule, extracting both ground and excited states without the need for auxiliary qubits or additional minimization. Further, we show that this extended protocol can mitigate the effects of incoherent errors, potentially enabling larger-scale quantum simulations without the need for complex error-correction techniques.

Lifetime impact on residual stress of EUV pellicle

NASA Astrophysics Data System (ADS)

Kim, Min-Woo; Lee, Sung-Gyu; Park, Eun-Sang; Oh, Hye-Keun

2017-10-01

Since EUV pellicle is very thin, It can be affected easily on its manufacturing process or the exposure process. The Pellicle has several types of stress, above all the pellicle has a residual stress from its manufacturing process. To determine the effect of residual stress on the pellicle, we calculated residual stress of several types of multi-layer pellicle by using formula. We could confirm that the residual stress has non-negligible values through the calculation results, and we obtained the thermal stress of each pellicle by using finite element method (FEM). we optimized the pellicle through comparison of total stress by plus the calculated residual stress and the thermal stress. As a result, since the p-Si core pellicle with B4C capping satisfies both high transparent and low total stress, we chose p-Si core pellicle with B4C capping as a suitable pellicle.

Computation of Molecular Spectra on a Quantum Processor with an Error-Resilient Algorithm

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

Colless, J. I.; Ramasesh, V. V.; Dahlen, D.

Harnessing the full power of nascent quantum processors requires the efficient management of a limited number of quantum bits with finite coherent lifetimes. Hybrid algorithms, such as the variational quantum eigensolver (VQE), leverage classical resources to reduce the required number of quantum gates. Experimental demonstrations of VQE have resulted in calculation of Hamiltonian ground states, and a new theoretical approach based on a quantum subspace expansion (QSE) has outlined a procedure for determining excited states that are central to dynamical processes. Here, we use a superconducting-qubit-based processor to apply the QSE approach to the H 2 molecule, extracting both groundmore » and excited states without the need for auxiliary qubits or additional minimization. Further, we show that this extended protocol can mitigate the effects of incoherent errors, potentially enabling larger-scale quantum simulations without the need for complex error-correction techniques.« less

Tailoring local density of optical states to control emission intensity and anisotropy of quantum dots in hybrid photonic-plasmonic templates

NASA Astrophysics Data System (ADS)

Indukuri, Chaitanya; Mukherjee, Arnab; Basu, J. K.

2015-03-01

We report results of controlled tuning of the local density of states (LDOS) in versatile, flexible, and hierarchical self assembled plasmonic templates. Using 5 nm diameter gold (Au) spherical nanoantenna within a polymer template randomly dispersed with quantum dots, we show how the photoluminescence intensity and lifetime anisotropy of these dots can be significantly enhanced through LDOS tuning. Finite difference time domain simulations corroborate the experimental observations and extend the regime of enhancement to a wider range of geometric and spectral parameters bringing out the versatility of these functional plasmonic templates. It is also demonstrated how the templates act as plasmonic resonators for effectively engineer giant enhancement of the scattering efficiency of these nano antenna embedded in the templates. Our work provides an alternative method to achieve spontaneous emission intensity and anisotropy enhancement with true nanoscale plasmon resonators.

Charge-Dependent Directed Flow in Cu + Au Collisions at s N N = 200 GeV

DOE PAGES

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

2017-01-05

Here we present the first measurement of charge-dependent directed flow in Cu + Au collisions atmore » $$\\sqrt{s}$$$_ {NN}$$ = 200 GeV . The results are presented as a function of the particle transverse momentum and pseudorapidity for different centralities. A finite difference between the directed flow of positive and negative charged particles is observed that qualitatively agrees with the expectations from the effects of the initial strong electric field between two colliding ions with different nuclear charges. The measured difference in directed flow is much smaller than that obtained from the parton-hadron-string-dynamics model, which suggests that most of the electric charges, i.e., quarks and antiquarks, have not yet been created during the lifetime of the strong electric field, which is of the order of, or less than, 1fm / c .« less

Dynamics of self-sustained asynchronous-irregular activity in random networks of spiking neurons with strong synapses

PubMed Central

Kriener, Birgit; Enger, Håkon; Tetzlaff, Tom; Plesser, Hans E.; Gewaltig, Marc-Oliver; Einevoll, Gaute T.

2014-01-01

Random networks of integrate-and-fire neurons with strong current-based synapses can, unlike previously believed, assume stable states of sustained asynchronous and irregular firing, even without external random background or pacemaker neurons. We analyze the mechanisms underlying the emergence, lifetime and irregularity of such self-sustained activity states. We first demonstrate how the competition between the mean and the variance of the synaptic input leads to a non-monotonic firing-rate transfer in the network. Thus, by increasing the synaptic coupling strength, the system can become bistable: In addition to the quiescent state, a second stable fixed-point at moderate firing rates can emerge by a saddle-node bifurcation. Inherently generated fluctuations of the population firing rate around this non-trivial fixed-point can trigger transitions into the quiescent state. Hence, the trade-off between the magnitude of the population-rate fluctuations and the size of the basin of attraction of the non-trivial rate fixed-point determines the onset and the lifetime of self-sustained activity states. During self-sustained activity, individual neuronal activity is moreover highly irregular, switching between long periods of low firing rate to short burst-like states. We show that this is an effect of the strong synaptic weights and the finite time constant of synaptic and neuronal integration, and can actually serve to stabilize the self-sustained state. PMID:25400575

Dynamics of self-sustained asynchronous-irregular activity in random networks of spiking neurons with strong synapses.

PubMed

Kriener, Birgit; Enger, Håkon; Tetzlaff, Tom; Plesser, Hans E; Gewaltig, Marc-Oliver; Einevoll, Gaute T

2014-01-01

Random networks of integrate-and-fire neurons with strong current-based synapses can, unlike previously believed, assume stable states of sustained asynchronous and irregular firing, even without external random background or pacemaker neurons. We analyze the mechanisms underlying the emergence, lifetime and irregularity of such self-sustained activity states. We first demonstrate how the competition between the mean and the variance of the synaptic input leads to a non-monotonic firing-rate transfer in the network. Thus, by increasing the synaptic coupling strength, the system can become bistable: In addition to the quiescent state, a second stable fixed-point at moderate firing rates can emerge by a saddle-node bifurcation. Inherently generated fluctuations of the population firing rate around this non-trivial fixed-point can trigger transitions into the quiescent state. Hence, the trade-off between the magnitude of the population-rate fluctuations and the size of the basin of attraction of the non-trivial rate fixed-point determines the onset and the lifetime of self-sustained activity states. During self-sustained activity, individual neuronal activity is moreover highly irregular, switching between long periods of low firing rate to short burst-like states. We show that this is an effect of the strong synaptic weights and the finite time constant of synaptic and neuronal integration, and can actually serve to stabilize the self-sustained state.

Theory of Positron Annihilation in Helium-Filled Bubbles in Plutonium

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

Sterne, P A; Pask, J E

2003-02-13

Positron annihilation lifetime spectroscopy is a sensitive probe of vacancies and voids in materials. This non-destructive measurement technique can identify the presence of specific defects in materials at the part-per-million level. Recent experiments by Asoka-Kumar et al. have identified two lifetime components in aged plutonium samples--a dominant lifetime component of around 182 ps and a longer lifetime component of around 350-400ps. This second component appears to increase with the age of the sample, and accounts for only about 5 percent of the total intensity in 35 year-old plutonium samples. First-principles calculations of positron lifetimes are now used extensively to guidemore » the interpretation of positron lifetime data. At Livermore, we have developed a first-principles finite-element-based method for calculating positron lifetimes for defects in metals. This method is capable of treating system cell sizes of several thousand atoms, allowing us to model defects in plutonium ranging in size from a mono-vacancy to helium-filled bubbles of over 1 nm in diameter. In order to identify the defects that account for the observed lifetime values, we have performed positron lifetime calculations for a set of vacancies, vacancy clusters, and helium-filled vacancy clusters in delta-plutonium. The calculations produced values of 143ps for defect-free delta-Pu and 255ps for a mono-vacancy in Pu, both of which are inconsistent with the dominant experimental lifetime component of 182ps. Larger vacancy clusters have even longer lifetimes. The observed positron lifetime is significantly shorter than the calculated lifetimes for mono-vacancies and larger vacancy clusters, indicating that open vacancy clusters are not the dominant defect in the aged plutonium samples. When helium atoms are introduced into the vacancy cluster, the positron lifetime is reduced due to the increased density of electrons available for annihilation. For a mono-vacancy in Pu containing one helium atom, the calculated lifetime is 190 ps, while a di-vacancy containing two helium atoms has a positron lifetime of 205 ps. In general, increasing the helium density in a vacancy cluster or He-filled bubble reduces the positron lifetime, so that the same lifetime value can arise fi-om a range of vacancy cluster sizes with different helium densities. In order to understand the variation of positron lifetime with vacancy cluster size and helium density in the defect, we have performed over 60 positron lifetime calculations with vacancy cluster sizes ranging from 1 to 55 vacancies and helium densities ranging fi-om zero to five helium atoms per vacancy. The results indicate that the experimental lifetime of 182 ps is consistent with the theoretical value of 190 ps for a mono-vacancy with a single helium atom, but that slightly better agreement is obtained for larger clusters of 6 or more vacancies containing 2-3 helium atoms per vacancy. For larger vacancy clusters with diameters of about 3-5 nm or more, the annihilation with helium electrons dominates the positron annihilation rate; the observed lifetime of 180ps is then consistent with a helium concentration in the range of 3 to 3.5 Hehacancy, setting an upper bound on the helium concentration in the vacancy clusters. In practice, the single lifetime component is most probably associated with a family of helium-filled bubbles rather than with a specific unique defect size. The longer 350-400ps lifetime component is consistent with a relatively narrow range of defect sizes and He concentration. At zero He concentration, the lifetime values are matched by small vacancy clusters containing 6-12 vacancies. With increasing vacancy cluster size, a small amount of He is required to keep the lifetime in the 350-400 ps range, until the value saturates for larger helium bubbles of more than 50 vacancies (bubble diameter > 1.3 nm) at a helium concentration close to 1 He/vacancy. These results, taken together with the experimental data, indicate that the features observed in TEM data by Schwartz et al are not voids, but are in fact helium-filled bubbles with a helium pressure of around 2-3 helium atoms per vacancy, depending on the bubble size. This is consistent with the conclusions of recently developed models of He-bubble growth in aged plutonium.« less

Thermomechanical Modeling of Sintered Silver - A Fracture Mechanics-based Approach: Extended Abstract: Preprint

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

Paret, Paul P; DeVoto, Douglas J; Narumanchi, Sreekant V

Sintered silver has proven to be a promising candidate for use as a die-attach and substrate-attach material in automotive power electronics components. It holds promise of greater reliability than lead-based and lead-free solders, especially at higher temperatures (less than 200 degrees Celcius). Accurate predictive lifetime models of sintered silver need to be developed and its failure mechanisms thoroughly characterized before it can be deployed as a die-attach or substrate-attach material in wide-bandgap device-based packages. We present a finite element method (FEM) modeling methodology that can offer greater accuracy in predicting the failure of sintered silver under accelerated thermal cycling. Amore » fracture mechanics-based approach is adopted in the FEM model, and J-integral/thermal cycle values are computed. In this paper, we outline the procedures for obtaining the J-integral/thermal cycle values in a computational model and report on the possible advantage of using these values as modeling parameters in a predictive lifetime model.« less

The relationship between lifetime health trajectories and socioeconomic attainment in middle age.

PubMed

Lee, Dohoon; Jackson, Margot

2015-11-01

A large literature demonstrates the direct and indirect influence of health on socioeconomic attainment, and reveals the ways in which health and socioeconomic background simultaneously and dynamically affect opportunities for attainment and mobility. Despite an increasing understanding of the effects of health on social processes, research to date remains limited in its conceptualization and measurement of the temporal dimensions of health, especially in the presence of socioeconomic circumstances that covary with health over time. Guided by life course theory, we use data from the British National Child Development Study, an ongoing panel study of a cohort born in 1958, to examine the association between lifetime health trajectories and socioeconomic attainment in middle age. We apply finite mixture modeling to identify distinct trajectories of health that simultaneously account for timing, duration and stability. Moreover, we employ propensity score weighting models to account for the presence of time-varying socioeconomic factors in estimating the impact of health trajectories. We find that, when poor health is limited to the childhood years, the disadvantage in socioeconomic attainment relative to being continuously healthy is either insignificant or largely explained by time-varying socioeconomic confounders. The socioeconomic impact of continuously deteriorating health over the life course is more persistent, however. Our results suggest that accounting for the timing, duration and stability of poor health throughout both childhood and adulthood is important for understanding how health works to produce social stratification. In addition, the findings highlight the importance of distinguishing between confounding and mediating effects of time-varying socioeconomic circumstances. Copyright © 2015 Elsevier Inc. All rights reserved.

The Relationship between Lifetime Health Trajectories and Socioeconomic Attainment in Middle Age

PubMed Central

Lee, Dohoon; Jackson, Margot

2015-01-01

A large literature demonstrates the direct and indirect influence of health on socioeconomic attainment, and reveals the ways in which health and socioeconomic background simultaneously and dynamically affect opportunities for attainment and mobility. Despite an increasing understanding of the effects of health on social processes, research to date remains limited in its conceptualization and measurement of the temporal dimensions of health, especially in the presence of socioeconomic circumstances that covary with health over time. Guided by life course theory, we use data from the British National Child Development Study, an ongoing panel study of a cohort born in 1958, to examine the association between lifetime health trajectories and socioeconomic attainment in middle age. We apply finite mixture modeling to identify distinct trajectories of health that simultaneously account for timing, duration and stability. Moreover, we employ propensity score weighting models to account for the presence of time-varying socioeconomic factors in estimating the impact of health trajectories. We find that, when poor health is limited to the childhood years, the disadvantage in socioeconomic attainment relative to being continuously healthy is either insignificant or largely explained by time-varying socioeconomic confounders. The socioeconomic impact of continuously deteriorating health over the life course is more persistent, however. Our results suggest that accounting for the timing, duration and stability of poor health throughout both childhood and adulthood is important for understanding how health works to produce social stratification. In addition, the findings highlight the importance of distinguishing between confounding and mediating effects of time-varying socioeconomic circumstances. PMID:26463537

Life Assessment of Steam Turbine Components Based on Viscoplastic Analysis

NASA Astrophysics Data System (ADS)

Choi, Woo-Sung; Fleury, Eric; Kim, Bum-Shin; Hyun, Jung-Seob

Unsteady thermal and mechanical loading in turbine components is caused due to the transient regimes arising during start-ups and shut-downs and due to changes in the operating regime in steam power plants; this results in nonuniform strain and stress distribution. Thus, an accurate knowledge of the stresses caused by various loading conditions is required to ensure the integrity and to ensure an accurate life assessment of the components of a turbine. Although the materials of the components of the steam turbine deform inelastically at a high temperature, currently, only elastic calculations are performed for safety and simplicity. Numerous models have been proposed to describe the viscoplastic (time-dependent) behavior; these models are rather elaborate and it is difficult to incorporate them into a finite element code in order to simulate the loading of complex structures. In this paper, the total lifetime of the components of a steam turbine was calculated by combining the viscoplastic constitutive equation with the ABAQUS finite element code. Viscoplastic analysis was conducted by focusing mainly on simplified constitutive equations with linear kinematic hardening, which is simple enough to be used effectively in computer simulation. The von Mises stress distribution of an HIP turbine rotor was calculated during the cold start-up operation of the rotor, and a reasonable number of cycles were obtained from the equation of Langer.

Exits in order: How crowding affects particle lifetimes

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

Penington, Catherine J.; Simpson, Matthew J.; Baker, Ruth E.

2016-06-28

Diffusive processes are often represented using stochastic random walk frameworks. The amount of time taken for an individual in a random walk to intersect with an absorbing boundary is a fundamental property that is often referred to as the particle lifetime, or the first passage time. The mean lifetime of particles in a random walk model of diffusion is related to the amount of time required for the diffusive process to reach a steady state. Mathematical analysis describing the mean lifetime of particles in a standard model of diffusion without crowding is well known. However, the lifetime of agents inmore » a random walk with crowding has received much less attention. Since many applications of diffusion in biology and biophysics include crowding effects, here we study a discrete model of diffusion that incorporates crowding. Using simulations, we show that crowding has a dramatic effect on agent lifetimes, and we derive an approximate expression for the mean agent lifetime that includes crowding effects. Our expression matches simulation results very well, and highlights the importance of crowding effects that are sometimes overlooked.« less

A self-contained quantum harmonic engine

NASA Astrophysics Data System (ADS)

Reid, B.; Pigeon, S.; Antezza, M.; De Chiara, G.

2017-12-01

We propose a system made of three quantum harmonic oscillators as a compact quantum engine for producing mechanical work. The three oscillators play respectively the role of the hot bath, the working medium and the cold bath. The working medium performs an Otto cycle during which its frequency is changed and it is sequentially coupled to each of the two other oscillators. As the two environments are finite, the lifetime of the machine is finite and after a number of cycles it stops working and needs to be reset. Remarkably, we show that this machine can extract more than 90% of the available energy during 70 cycles. Differently from usually investigated infinite-reservoir configurations, this machine allows the protection of induced quantum correlations and we analyse the entanglement and quantum discord generated during the strokes. Interestingly, we show that high work generation is always accompanied by large quantum correlations. Our predictions can be useful for energy management at the nanoscale, and can be relevant for experiments with trapped ions and experiments with light in integrated optical circuits.

Age and Pathway Diagnostics for a Stratospheric General Circulation Model

NASA Technical Reports Server (NTRS)

Schoeberl, Mark R.; Douglass, Anne R.; Polansky, Brian

2004-01-01

Using a variety of age diagnostic experiments we examine the stratospheric age spectrum of the Goddard Finite Volume Generd Circulation Model. Pulse tracer release age-of-air computations are compared to forward and backward trajectory computations. These comparisons show good agreement, and the age-of-air also compares well with observed long lived tracers. Pathway diagnostics show how air arrives in the lowermost stratosphere and the age structure of that region. Using tracers with different lifetimes we can estimate the age spectrum - this technique should be useful in diagnosing transport from various trace gas observations.

Er3+-doped BaY2F8 crystal waveguides for broadband optical amplification at 1.5 μm

NASA Astrophysics Data System (ADS)

Toccafondo, V.; Cerqueira S., A.; Faralli, S.; Sani, E.; Toncelli, A.; Tonelli, M.; Di Pasquale, F.

2007-01-01

Integrated waveguide amplifiers based on high concentration Er3+ doped BaY2F8 crystals are numerically studied by combining a full-vectorial finite element based modal analysis and propagation-rate equations. Using realistic input data, such as the absorption/emission cross sections and Er level lifetimes measured on grown crystal samples, we investigate the amplifier performance by optimizing the total Er concentration. We predict optimum gain coefficient up to 5dB/cm and broad amplification bandwidth exceeding 80nm with 1480nm pumping.

Time-dependent fiber bundles with local load sharing. II. General Weibull fibers.

PubMed

Phoenix, S Leigh; Newman, William I

2009-12-01

Fiber bundle models (FBMs) are useful tools in understanding failure processes in a variety of material systems. While the fibers and load sharing assumptions are easily described, FBM analysis is typically difficult. Monte Carlo methods are also hampered by the severe computational demands of large bundle sizes, which overwhelm just as behavior relevant to real materials starts to emerge. For large size scales, interest continues in idealized FBMs that assume either equal load sharing (ELS) or local load sharing (LLS) among fibers, rules that reflect features of real load redistribution in elastic lattices. The present work focuses on a one-dimensional bundle of N fibers under LLS where life consumption in a fiber follows a power law in its load, with exponent rho , and integrated over time. This life consumption function is further embodied in a functional form resulting in a Weibull distribution for lifetime under constant fiber stress and with Weibull exponent, beta. Thus the failure rate of a fiber depends on its past load history, except for beta=1 . We develop asymptotic results validated by Monte Carlo simulation using a computational algorithm developed in our previous work [Phys. Rev. E 63, 021507 (2001)] that greatly increases the size, N , of treatable bundles (e.g., 10(6) fibers in 10(3) realizations). In particular, our algorithm is O(N ln N) in contrast with former algorithms which were O(N2) making this investigation possible. Regimes are found for (beta,rho) pairs that yield contrasting behavior for large N. For rho>1 and large N, brittle weakest volume behavior emerges in terms of characteristic elements (groupings of fibers) derived from critical cluster formation, and the lifetime eventually goes to zero as N-->infinity , unlike ELS, which yields a finite limiting mean. For 1/21 but with 0

Time-dependent fiber bundles with local load sharing. II. General Weibull fibers

NASA Astrophysics Data System (ADS)

Phoenix, S. Leigh; Newman, William I.

2009-12-01

Fiber bundle models (FBMs) are useful tools in understanding failure processes in a variety of material systems. While the fibers and load sharing assumptions are easily described, FBM analysis is typically difficult. Monte Carlo methods are also hampered by the severe computational demands of large bundle sizes, which overwhelm just as behavior relevant to real materials starts to emerge. For large size scales, interest continues in idealized FBMs that assume either equal load sharing (ELS) or local load sharing (LLS) among fibers, rules that reflect features of real load redistribution in elastic lattices. The present work focuses on a one-dimensional bundle of N fibers under LLS where life consumption in a fiber follows a power law in its load, with exponent ρ , and integrated over time. This life consumption function is further embodied in a functional form resulting in a Weibull distribution for lifetime under constant fiber stress and with Weibull exponent, β . Thus the failure rate of a fiber depends on its past load history, except for β=1 . We develop asymptotic results validated by Monte Carlo simulation using a computational algorithm developed in our previous work [Phys. Rev. EPLEEE81063-651X 63, 021507 (2001)] that greatly increases the size, N , of treatable bundles (e.g., 106 fibers in 103 realizations). In particular, our algorithm is O(NlnN) in contrast with former algorithms which were O(N2) making this investigation possible. Regimes are found for (β,ρ) pairs that yield contrasting behavior for large N . For ρ>1 and large N , brittle weakest volume behavior emerges in terms of characteristic elements (groupings of fibers) derived from critical cluster formation, and the lifetime eventually goes to zero as N→∞ , unlike ELS, which yields a finite limiting mean. For 1/2≤ρ≤1 , however, LLS has remarkably similar behavior to ELS (appearing to be virtually identical for ρ=1 ) with an asymptotic Gaussian lifetime distribution and a finite limiting mean for large N . The coefficient of variation follows a power law in increasing N but, except for ρ=1 , the value of the negative exponent is clearly less than 1/2 unlike in ELS bundles where the exponent remains 1/2 for 1/2<ρ≤1 . For sufficiently small values 0<ρ≪1 , a transition occurs, depending on β , whereby LLS bundle lifetimes become dominated by a few long-lived fibers. Thus the bundle lifetime appears to approximately follow an extreme-value distribution for the longest lived of a parallel group of independent elements, which applies exactly to ρ=0 . The lower the value of β , the higher the transition value of ρ , below which such extreme-value behavior occurs. No evidence was found for limiting Gaussian behavior for ρ>1 but with 0<β(ρ+1)<1 , as might be conjectured from quasistatic bundle models where β(ρ+1) mimics the Weibull exponent for fiber strength.

A minimization principle for the description of modes associated with finite-time instabilities

PubMed Central

Babaee, H.

2016-01-01

We introduce a minimization formulation for the determination of a finite-dimensional, time-dependent, orthonormal basis that captures directions of the phase space associated with transient instabilities. While these instabilities have finite lifetime, they can play a crucial role either by altering the system dynamics through the activation of other instabilities or by creating sudden nonlinear energy transfers that lead to extreme responses. However, their essentially transient character makes their description a particularly challenging task. We develop a minimization framework that focuses on the optimal approximation of the system dynamics in the neighbourhood of the system state. This minimization formulation results in differential equations that evolve a time-dependent basis so that it optimally approximates the most unstable directions. We demonstrate the capability of the method for two families of problems: (i) linear systems, including the advection–diffusion operator in a strongly non-normal regime as well as the Orr–Sommerfeld/Squire operator, and (ii) nonlinear problems, including a low-dimensional system with transient instabilities and the vertical jet in cross-flow. We demonstrate that the time-dependent subspace captures the strongly transient non-normal energy growth (in the short-time regime), while for longer times the modes capture the expected asymptotic behaviour. PMID:27118900

Molecular dynamics simulations of diffusion and clustering along critical isotherms of medium-chain n-alkanes.

PubMed

Mutoru, J W; Smith, W; O'Hern, C S; Firoozabadi, A

2013-01-14

Understanding the transport properties of molecular fluids in the critical region is important for a number of industrial and natural systems. In the literature, there are conflicting reports on the behavior of the self diffusion coefficient D(s) in the critical region of single-component molecular systems. For example, D(s) could decrease to zero, reach a maximum, or remain unchanged and finite at the critical point. Moreover, there is no molecular-scale understanding of the behavior of diffusion coefficients in molecular fluids in the critical regime. We perform extensive molecular dynamics simulations in the critical region of single-component fluids composed of medium-chain n-alkanes-n-pentane, n-decane, and n-dodecane-that interact via anisotropic united-atom potentials. For each system, we calculate D(s), and average molecular cluster sizes κ(cl) and numbers N(cl) at various cluster lifetimes τ, as a function of density ρ in the range 0.2ρ(c) ≤ ρ ≤ 2.0ρ(c) at the critical temperature T(c). We find that D(s) decreases with increasing ρ but remains finite at the critical point. Moreover, for any given τ < 1.2 × 10(-12) s, κ(cl) increases with increasing ρ but is also finite at the critical point.

Education and Lifetime Earnings in the United States

PubMed Central

Tamborini, Christopher R.; Kim, ChangHwan; Sakamoto, Arthur

2015-01-01

Differences in lifetime earnings by educational attainment have been of great research and policy interest. Although a large literature examines earnings differences by educational attainment, research on lifetime earnings—which refers to total accumulated earnings from entry into the labor market until retirement—remains limited because of the paucity of adequate data. Using data that match respondents in the Survey of Income and Program Participation to their longitudinal tax earnings as recorded by the Social Security Administration, we estimate the 50-year work career effects of education on lifetime earnings for men and women. By overcoming the purely synthetic cohort approach, our results provide a more realistic appraisal of actual patterns of lifetime earnings. Detailed estimates are provided for gross lifetime earnings by education; net lifetime earnings after controlling for covariates associated with the probability of obtaining a bachelor’s degree; and the net present 50-year lifetime value of education at age 20. In addition, we provide estimates that include individuals with zero earnings and disability. We also assess the adequacy of the purely synthetic cohort approach, which uses age differences in earnings observed in cross-sectional surveys to approximate lifetime earnings. Overall, our results confirm the persistent positive effects of higher education on earnings over different stages of the work career and over a lifetime, but also reveal notably smaller net effects on lifetime earnings compared with previously reported estimates. We discuss the implications of these and other findings. PMID:26100983

Education and Lifetime Earnings in the United States.

PubMed

Tamborini, Christopher R; Kim, ChangHwan; Sakamoto, Arthur

2015-08-01

Differences in lifetime earnings by educational attainment have been of great research and policy interest. Although a large literature examines earnings differences by educational attainment, research on lifetime earnings--which refers to total accumulated earnings from entry into the labor market until retirement--remains limited because of the paucity of adequate data. Using data that match respondents in the Survey of Income and Program Participation to their longitudinal tax earnings as recorded by the Social Security Administration, we estimate the 50-year work career effects of education on lifetime earnings for men and women. By overcoming the purely synthetic cohort approach, our results provide a more realistic appraisal of actual patterns of lifetime earnings. Detailed estimates are provided for gross lifetime earnings by education; net lifetime earnings after controlling for covariates associated with the probability of obtaining a bachelor's degree; and the net present 50-year lifetime value of education at age 20. In addition, we provide estimates that include individuals with zero earnings and disability. We also assess the adequacy of the purely synthetic cohort approach, which uses age differences in earnings observed in cross-sectional surveys to approximate lifetime earnings. Overall, our results confirm the persistent positive effects of higher education on earnings over different stages of the work career and over a lifetime, but also reveal notably smaller net effects on lifetime earnings compared with previously reported estimates. We discuss the implications of these and other findings.

Unified nano-mechanics based probabilistic theory of quasibrittle and brittle structures: I. Strength, static crack growth, lifetime and scaling

NASA Astrophysics Data System (ADS)

Le, Jia-Liang; Bažant, Zdeněk P.; Bazant, Martin Z.

2011-07-01

Engineering structures must be designed for an extremely low failure probability such as 10 -6, which is beyond the means of direct verification by histogram testing. This is not a problem for brittle or ductile materials because the type of probability distribution of structural strength is fixed and known, making it possible to predict the tail probabilities from the mean and variance. It is a problem, though, for quasibrittle materials for which the type of strength distribution transitions from Gaussian to Weibullian as the structure size increases. These are heterogeneous materials with brittle constituents, characterized by material inhomogeneities that are not negligible compared to the structure size. Examples include concrete, fiber composites, coarse-grained or toughened ceramics, rocks, sea ice, rigid foams and bone, as well as many materials used in nano- and microscale devices. This study presents a unified theory of strength and lifetime for such materials, based on activation energy controlled random jumps of the nano-crack front, and on the nano-macro multiscale transition of tail probabilities. Part I of this study deals with the case of monotonic and sustained (or creep) loading, and Part II with fatigue (or cyclic) loading. On the scale of the representative volume element of material, the probability distribution of strength has a Gaussian core onto which a remote Weibull tail is grafted at failure probability of the order of 10 -3. With increasing structure size, the Weibull tail penetrates into the Gaussian core. The probability distribution of static (creep) lifetime is related to the strength distribution by the power law for the static crack growth rate, for which a physical justification is given. The present theory yields a simple relation between the exponent of this law and the Weibull moduli for strength and lifetime. The benefit is that the lifetime distribution can be predicted from short-time tests of the mean size effect on strength and tests of the power law for the crack growth rate. The theory is shown to match closely numerous test data on strength and static lifetime of ceramics and concrete, and explains why their histograms deviate systematically from the straight line in Weibull scale. Although the present unified theory is built on several previous advances, new contributions are here made to address: (i) a crack in a disordered nano-structure (such as that of hydrated Portland cement), (ii) tail probability of a fiber bundle (or parallel coupling) model with softening elements, (iii) convergence of this model to the Gaussian distribution, (iv) the stress-life curve under constant load, and (v) a detailed random walk analysis of crack front jumps in an atomic lattice. The nonlocal behavior is captured in the present theory through the finiteness of the number of links in the weakest-link model, which explains why the mean size effect coincides with that of the previously formulated nonlocal Weibull theory. Brittle structures correspond to the large-size limit of the present theory. An important practical conclusion is that the safety factors for strength and tolerable minimum lifetime for large quasibrittle structures (e.g., concrete structures and composite airframes or ship hulls, as well as various micro-devices) should be calculated as a function of structure size and geometry.

Comment Comparison of the fluorescence lifetimes of Cr 3+ in crystals, glasses and glass ceramics and their use to interpret the effect of pressure on ruby

NASA Astrophysics Data System (ADS)

Champagnon, B.; Pilla, O.

1989-09-01

A correlation has been proposed by Urošević Panić Jovanić, Zeković and Savić between the lifetimes of Cr 3+ in various environments and the Dq parameter of ligand field theory. We show that these observed lifetimes depend on various factors such as multisite effects, reabsorption, thermal excitation or 2E 4T 2 mixing. The correlation between lifetimes and pressure on ruby has to consider these different effects.

Aging in mortal superdiffusive Lévy walkers.

PubMed

Stage, Helena

2017-12-01

A growing body of literature examines the effects of superdiffusive subballistic movement premeasurement (aging or time lag) on observations arising from single-particle tracking. A neglected aspect is the finite lifetime of these Lévy walkers, be they proteins, cells, or larger structures. We examine the effects of aging on the motility of mortal walkers, and discuss the means by which permanent stopping of walkers may be categorized as arising from "natural" death or experimental artifacts such as low photostability or radiation damage. This is done by comparison of the walkers' mean squared displacement (MSD) with the front velocity of propagation of a group of walkers, which is found to be invariant under time lags. For any running time distribution of a mortal random walker, the MSD is tempered by the stopping rate θ. This provides a physical interpretation for truncated heavy-tailed diffusion processes and serves as a tool by which to better classify the underlying running time distributions of random walkers. Tempering of aged MSDs raises the issue of misinterpreting superdiffusive motion which appears Brownian or subdiffusive over certain time scales.

Aging in mortal superdiffusive Lévy walkers

NASA Astrophysics Data System (ADS)

Stage, Helena

2017-12-01

A growing body of literature examines the effects of superdiffusive subballistic movement premeasurement (aging or time lag) on observations arising from single-particle tracking. A neglected aspect is the finite lifetime of these Lévy walkers, be they proteins, cells, or larger structures. We examine the effects of aging on the motility of mortal walkers, and discuss the means by which permanent stopping of walkers may be categorized as arising from "natural" death or experimental artifacts such as low photostability or radiation damage. This is done by comparison of the walkers' mean squared displacement (MSD) with the front velocity of propagation of a group of walkers, which is found to be invariant under time lags. For any running time distribution of a mortal random walker, the MSD is tempered by the stopping rate θ . This provides a physical interpretation for truncated heavy-tailed diffusion processes and serves as a tool by which to better classify the underlying running time distributions of random walkers. Tempering of aged MSDs raises the issue of misinterpreting superdiffusive motion which appears Brownian or subdiffusive over certain time scales.

Moments of action provide insight into critical times for advection-diffusion-reaction processes.

PubMed

Ellery, Adam J; Simpson, Matthew J; McCue, Scott W; Baker, Ruth E

2012-09-01

Berezhkovskii and co-workers introduced the concept of local accumulation time as a finite measure of the time required for the transient solution of a reaction-diffusion equation to effectively reach steady state [Biophys J. 99, L59 (2010); Phys. Rev. E 83, 051906 (2011)]. Berezhkovskii's approach is a particular application of the concept of mean action time (MAT) that was introduced previously by McNabb [IMA J. Appl. Math. 47, 193 (1991)]. Here, we generalize these previous results by presenting a framework to calculate the MAT, as well as the higher moments, which we call the moments of action. The second moment is the variance of action time, the third moment is related to the skew of action time, and so on. We consider a general transition from some initial condition to an associated steady state for a one-dimensional linear advection-diffusion-reaction partial differential equation (PDE). Our results indicate that it is possible to solve for the moments of action exactly without requiring the transient solution of the PDE. We present specific examples that highlight potential weaknesses of previous studies that have considered the MAT alone without considering higher moments. Finally, we also provide a meaningful interpretation of the moments of action by presenting simulation results from a discrete random-walk model together with some analysis of the particle lifetime distribution. This work shows that the moments of action are identical to the moments of the particle lifetime distribution for certain transitions.

Random transitions described by the stochastic Smoluchowski-Poisson system and by the stochastic Keller-Segel model.

PubMed

Chavanis, P H; Delfini, L

2014-03-01

We study random transitions between two metastable states that appear below a critical temperature in a one-dimensional self-gravitating Brownian gas with a modified Poisson equation experiencing a second order phase transition from a homogeneous phase to an inhomogeneous phase [P. H. Chavanis and L. Delfini, Phys. Rev. E 81, 051103 (2010)]. We numerically solve the N-body Langevin equations and the stochastic Smoluchowski-Poisson system, which takes fluctuations (finite N effects) into account. The system switches back and forth between the two metastable states (bistability) and the particles accumulate successively at the center or at the boundary of the domain. We explicitly show that these random transitions exhibit the phenomenology of the ordinary Kramers problem for a Brownian particle in a double-well potential. The distribution of the residence time is Poissonian and the average lifetime of a metastable state is given by the Arrhenius law; i.e., it is proportional to the exponential of the barrier of free energy ΔF divided by the energy of thermal excitation kBT. Since the free energy is proportional to the number of particles N for a system with long-range interactions, the lifetime of metastable states scales as eN and is considerable for N≫1. As a result, in many applications, metastable states of systems with long-range interactions can be considered as stable states. However, for moderate values of N, or close to a critical point, the lifetime of the metastable states is reduced since the barrier of free energy decreases. In that case, the fluctuations become important and the mean field approximation is no more valid. This is the situation considered in this paper. By an appropriate change of notations, our results also apply to bacterial populations experiencing chemotaxis in biology. Their dynamics can be described by a stochastic Keller-Segel model that takes fluctuations into account and goes beyond the usual mean field approximation.

Double inverse-weighted estimation of cumulative treatment effects under nonproportional hazards and dependent censoring.

PubMed

Schaubel, Douglas E; Wei, Guanghui

2011-03-01

In medical studies of time-to-event data, nonproportional hazards and dependent censoring are very common issues when estimating the treatment effect. A traditional method for dealing with time-dependent treatment effects is to model the time-dependence parametrically. Limitations of this approach include the difficulty to verify the correctness of the specified functional form and the fact that, in the presence of a treatment effect that varies over time, investigators are usually interested in the cumulative as opposed to instantaneous treatment effect. In many applications, censoring time is not independent of event time. Therefore, we propose methods for estimating the cumulative treatment effect in the presence of nonproportional hazards and dependent censoring. Three measures are proposed, including the ratio of cumulative hazards, relative risk, and difference in restricted mean lifetime. For each measure, we propose a double inverse-weighted estimator, constructed by first using inverse probability of treatment weighting (IPTW) to balance the treatment-specific covariate distributions, then using inverse probability of censoring weighting (IPCW) to overcome the dependent censoring. The proposed estimators are shown to be consistent and asymptotically normal. We study their finite-sample properties through simulation. The proposed methods are used to compare kidney wait-list mortality by race. © 2010, The International Biometric Society.

The roles of the immune system in women's reproduction: evolutionary constraints and life history trade-offs.

PubMed

Abrams, Elizabeth T; Miller, Elizabeth M

2011-01-01

Life history theory posits that, as long as survival is assured, finite resources are available for reproduction, maintenance, and growth/storage. To maximize lifetime reproductive success, resources are subject to trade-offs both within individuals and between current and future investment. For women, reproducing is costly and time-consuming; the bulk of available resources must be allocated to reproduction at the expense of more flexible systems like immune function. When reproducing women contract infectious diseases, the resources required for immune activation can fundamentally shift the patterns of resource allocation. Adding to the complexity of the reproductive-immune trade-offs in women are the pleiotropic effects of many immune factors, which were modified to serve key roles in mammalian reproduction. In this review, we explore the complex intersections between immune function and female reproduction to situate proximate immunological processes within a life history framework. After a brief overview of the immune system, we discuss some important physiological roles of immune factors in women's reproduction and the conflicts that may arise when these factors must play dual roles. We then discuss the influence of reproductive-immune trade-offs on the patterning of lifetime reproductive success: (1) the effect of immune activation/infectious disease on the timing of life history events; (2) the role of the immune system, immune activation, and infectious disease on resource allocation within individual reproductive events, particularly pregnancy; and (3) the role of the immune system in shaping the offspring's patterns of future life history trade-offs. We close with a discussion of future directions in reproductive immunology for anthropologists. Copyright © 2011 Wiley Periodicals, Inc.

The effect of light soaking on crystalline silicon surface passivation by atomic layer deposited Al2O3

NASA Astrophysics Data System (ADS)

Liao, Baochen; Stangl, Rolf; Mueller, Thomas; Lin, Fen; Bhatia, Charanjit S.; Hoex, Bram

2013-01-01

The effect of light soaking of crystalline silicon wafer lifetime samples surface passivated by thermal atomic layer deposited (ALD) Al2O3 is investigated in this paper. Contrary to other passivation materials used in solar cell applications (i.e., SiO2, SiNx), using thermal ALD Al2O3, an increase in effective carrier lifetime after light soaking under standard testing conditions is observed for both p-type (˜45%) and n-type (˜60%) FZ c-Si lifetime samples. After light soaking and storing the samples in a dark and dry environment, the effective lifetime decreases again and practically returns to the value before light soaking. The rate of lifetime decrease after light soaking is significantly slower than the rate of lifetime increase by light soaking. To investigate the underlying mechanism, corona charge experiments are carried out on p-type c-Si samples before and after light soaking. The results indicate that the negative fixed charge density Qf present in the Al2O3 films increases due to the light soaking, which results in an improved field-effect passivation. Numerical calculations also confirm that the improved field-effect passivation is the main contributor for the increased effective lifetime after light soaking. To further understand the light soaking phenomenon, a kinetic model—a charge trapping/de-trapping model—is proposed to explain the time dependent behavior of the lifetime increase/decrease observed under/after light soaking. The trap model fits the experimental results very well. The observed light enhanced passivation for ALD Al2O3 passivated c-Si is of technological relevance, because solar cell devices operate under illumination, thus an increase in solar cell efficiency due to light soaking can be expected.

The Arrow of Time In a Universe with a Positive Cosmological Constant Λ

NASA Astrophysics Data System (ADS)

Mersini-Houghton, Laura

There is a mounting evidence that our universe is propelled into an accelerated expansion driven by Dark Energy. The simplest form of Dark Energy is a cosmological constant Λ, which is woven into the fabric of spacetime. For this reason it is often referred to as vacuum energy. It has the "strange" property of maintaining a constant energy density despite the expanding volume of the universe. Universes whose energy ismade of Λ posses an event horizon with and eternally finite constant temperature and entropy, and are known as DeSitter geometries. Since the entropy of DeSitter spaces remains a finite constant, then the meaning of a thermodynamic arrow of time becomes unclear. Here we explore the consequences of a fundamental cosmological constant Λ for our universe. We show that when the gravitational entropy of a pure DeSitter state ultimately dominates over the matter entropy, then the thermodynamic arrow of time in our universe may reverse in scales of order a Hubble time. We find that due to the dynamics of gravity and entanglement with other domain, a finite size system such as a DeSitter patch with horizon size H 0 -1 has a finite lifetime ∆t. This phenomenon arises from the dynamic gravitational instabilities that develop during a DeSitter epoch and turn catastrophic. A reversed arrow of time is in disagreementwith observations. Thus we explore the possibilities that: Nature may not favor a fundamental Λ, or else general relativity may be modified in the infrared regime when Λ dominates the expansion of the Universe.

Lifetime racial/ethnic discrimination and ambulatory blood pressure: The moderating effect of age

PubMed Central

Moody, Danielle L. Beatty; Waldstein, Shari R.; Tobin, Jonathan; Cassels, Andrea; Schwartz, Joseph C.; Brondolo, Elizabeth

2016-01-01

Objective To determine if the relationships of lifetime discrimination to ambulatory blood pressure (ABP) varied as a function of age in a sample of Black and Latino(a) adults ages 19 – 65. Methods Participants were 607 Black (n = 318) and Latino(a) (n = 289) adults (49% female) who completed the Perceived Ethnic Discrimination Questionnaire-Community Version (PEDQ-CV), which assesses lifetime exposure to racism/ethnic discrimination. They were outfitted with an ABP monitor to assess systolic and diastolic blood pressure (SBP, DBP) across a 24-hour period. Mixed-level modeling was conducted to examine potential interactive effects of lifetime discrimination and age to 24-hour, daytime, and nighttime ABP after adjustment for demographic, socioeconomic, personality and life stress characteristics, and substance consumption covariates (e.g., smoking, alcohol). Results There were significant interactions of Age × Lifetime Discrimination on 24-hour and daytime DBP (ps ≤ .04), and in particular significant interactions for the Social Exclusion component of Lifetime Discrimination. Post-hoc probing of the interactions revealed the effects of Lifetime Discrimination on DBP were seen for older, but not younger participants. Lifetime discrimination was significantly positively associated with nocturnal SBP, and these effects were not moderated by age. All associations of Lifetime Discrimination to ABP remained significant controlling for recent exposure to discrimination as well as all other covariates. Conclusions Exposure to racial/ethnic discrimination across the life course is associated with elevated ABP in middle to older aged Black and Latino(a) adults. Further research is needed to understand the mechanisms linking discrimination to ABP over the life course. PMID:27018724

Lifetime racial/ethnic discrimination and ambulatory blood pressure: The moderating effect of age.

PubMed

Beatty Moody, Danielle L; Waldstein, Shari R; Tobin, Jonathan N; Cassells, Andrea; Schwartz, Joseph C; Brondolo, Elizabeth

2016-04-01

To determine whether the relationships of lifetime discrimination to ambulatory blood pressure (ABP) varied as a function of age in a sample of Black and Latino(a) adults ages 19 - 65. Participants were 607 Black (n = 318) and Latino(a) (n = 289) adults (49% female) who completed the Perceived Ethnic Discrimination Questionnaire-Community Version (PEDQ-CV), which assesses lifetime exposure to racism/ethnic discrimination. They were outfitted with an ABP monitor to assess systolic and diastolic blood pressure (SBP, DBP) across a 24-hr period. Mixed-level modeling was conducted to examine potential interactive effects of lifetime discrimination and age to 24-hr, daytime, and nighttime ABP after adjustment for demographic, socioeconomic, personality and life stress characteristics, and substance consumption covariates (e.g., smoking, alcohol). There were significant interactions of Age × Lifetime Discrimination on 24-hr and daytime DBP (ps ≤ .04), and in particular significant interactions for the Social Exclusion component of Lifetime Discrimination. Post hoc probing of the interactions revealed the effects of Lifetime Discrimination on DBP were seen for older, but not younger participants. Lifetime discrimination was significantly positively associated with nocturnal SBP, and these effects were not moderated by age. All associations of Lifetime Discrimination to ABP remained significant controlling for recent exposure to discrimination as well as all other covariates. Exposure to racial/ethnic discrimination across the life course is associated with elevated ABP in middle to older aged Black and Latino(a) adults. Further research is needed to understand the mechanisms linking discrimination to ABP over the life course. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

The evaporation of dense sprays as a mixing process

NASA Astrophysics Data System (ADS)

de Rivas, Alois; Villermaux, Emmanuel

2014-11-01

A dense spray of micron-sized droplets (water or ethanol) is formed in air by a pneumatic atomizer in a closed chamber, and is then conveyed through a nozzle in ambient air, forming a plume whose extension depends on the relative humidity of the diluting medium. We focus on the dry ambient medium, and large plume Reynolds number limit. Standard shear instabilities develop at the plume edge, forming the stretched lamellar structures familiar with passive scalars, except that these vanish in a finite time, because individual droplets evaporate at their border. Experiments also demonstrate that the lifetime of an individual droplet embedded in a lamellae is much larger than expected from the usual d-square law for an isolated droplet. By analogy with the way mixing times are understood from the convection-diffusion equation for passive scalars, we show that the lifetime of a lamellae stretched at a rate γ is tv =1/γ ln (1/+ ϕ ϕ ) where ϕ is a parameter which incorporates the thermodynamic and diffusional properties of the vapor in the diluting phase. The droplets field thus behaves as a -non conserved- passive scalar.

Octoxy capped Si nanoparticles synthesized by homogeneous reduction of SiCl4 with crown ether alkalide.

PubMed

Sletnes, M; Maria, J; Grande, T; Lindgren, M; Einarsrud, M-A

2014-02-07

Blue-green luminescent octoxy capped Si nanoparticles were synthesized via homogeneous reduction of SiCl4 with the crown ether alkalide K(+)(15-crown-5)2K(-) in tetrahydrofuran. The Si nanoparticles were characterized with respect to size, crystal structure, morphology, surface termination, optical properties and stability. Si diamond structure nanoparticles with narrow size distributions, and average diameters ranging from 3 to 7 nm were obtained. A finite-size effect on the lattice dimensions was observed, in the form of an expansion of the [220] lattice planes of smaller Si nanoparticles. The concentration of SiCl4 was found to be the most important parameter governing the particle size and size distribution. The octoxy capped particles were stable under an ambient atmosphere for at least one month, but exposure to water made them prone to oxidation. An average radiative recombination lifetime of 8.8 ns was measured for the blue-green luminescence. The luminescence appears to originate from surface defects, rather than from quantum confinement.

Disaggregation of small, cohesive rubble pile asteroids due to YORP

NASA Astrophysics Data System (ADS)

Scheeres, D. J.

2018-04-01

The implication of small amounts of cohesion within relatively small rubble pile asteroids is investigated with regard to their evolution under the persistent presence of the YORP effect. We find that below a characteristic size, which is a function of cohesive strength, density and other properties, rubble pile asteroids can enter a "disaggregation phase" in which they are subject to repeated fissions after which the formation of a stabilizing binary system is not possible. Once this threshold is passed rubble pile asteroids may be disaggregated into their constituent components within a finite time span. These constituent components will have their own spin limits - albeit potentially at a much higher spin rate due to the greater strength of a monolithic body. The implications of this prediction are discussed and include modification of size distributions, prevalence of monolithic bodies among meteoroids and the lifetime of small rubble pile bodies in the solar system. The theory is then used to place constraints on the strength of binary asteroids characterized as a function of their type.

Thermal stress analysis of sulfur deactivated solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Zeng, Shumao; Parbey, Joseph; Yu, Guangsen; Xu, Min; Li, Tingshuai; Andersson, Martin

2018-03-01

Hydrogen sulfide in fuels can deactivate catalyst for solid oxide fuel cells, which has become one of the most critical challenges to stability. The reactions between sulfur and catalyst will cause phase changes, leading to increase in cell polarization and mechanical mismatch. A three-dimensional computational fluid dynamics (CFD) approach based on the finite element method (FEM) is thus used to investigate the polarization, temperature and thermal stress in a sulfur deactivated SOFC by coupling equations for gas-phase species, heat, momentum, ion and electron transport. The results indicate that sulfur in fuels can strongly affect the cell polarization and thermal stresses, which shows a sharp decrease in the vicinity of electrolyte when 10% nickel in the functional layer is poisoned, but they remain almost unchanged even when the poisoned Ni content was increased to 90%. This investigation is helpful to deeply understand the sulfur poisoning effects and also benefit the material design and optimization of electrode structure to enhance cell performance and lifetimes in various hydrocarbon fuels containing impurities.

Deployment-based lifetime optimization for linear wireless sensor networks considering both retransmission and discrete power control.

PubMed

Li, Ruiying; Ma, Wenting; Huang, Ning; Kang, Rui

2017-01-01

A sophisticated method for node deployment can efficiently reduce the energy consumption of a Wireless Sensor Network (WSN) and prolong the corresponding network lifetime. Pioneers have proposed many node deployment based lifetime optimization methods for WSNs, however, the retransmission mechanism and the discrete power control strategy, which are widely used in practice and have large effect on the network energy consumption, are often neglected and assumed as a continuous one, respectively, in the previous studies. In this paper, both retransmission and discrete power control are considered together, and a more realistic energy-consumption-based network lifetime model for linear WSNs is provided. Using this model, we then propose a generic deployment-based optimization model that maximizes network lifetime under coverage, connectivity and transmission rate success constraints. The more accurate lifetime evaluation conduces to a longer optimal network lifetime in the realistic situation. To illustrate the effectiveness of our method, both one-tiered and two-tiered uniformly and non-uniformly distributed linear WSNs are optimized in our case studies, and the comparisons between our optimal results and those based on relatively inaccurate lifetime evaluation show the advantage of our method when investigating WSN lifetime optimization problems.

Novel exciton systems in 2D TMD monolayers and heterobilayers

NASA Astrophysics Data System (ADS)

Yu, Hongyi

In this talk, two exciton systems in transition metal dichalcogenides (TMDs) monolayer and heterobilayer will be discussed. In TMD monolayers, the strong e-h Coulomb exchange interaction splits the exciton and trion dispersions into two branches with zero and finite gap, respectively. Each branch is a center-of-mass wave vector dependent coherent superposition of the two valleys, which leads to a valley-orbit coupling and possibly a trion valley Hall effect. The exchange interaction also eliminates the linear polarization of the negative trion PL emission. In TMD heterobilayers with a type-II band alignment, the low energy exciton has an interlayer configuration with the e and h localized in opposite layers. Because of the inevitable twist or/and lattice mismatch between the two layers, the bright interlayer excitons are located at finite center-of-mass velocities with a six-fold degeneracy. The corresponding photon emission is elliptically polarized, with the major axis locked to the direction of exciton velocity, and helicity determined by the valley indices of the e and h. Some experimental results on the interlayer excitons in the WSe2-MoSe2 heterobilayers will also be presented. The interlayer exciton exhibits a long lifetime as well as a long depolarization time, which facilitate the observation of a PL polarization ring pattern due to the valley dependent exciton-exciton interaction induced expansion. The works were supported by the Research Grant Council of Hong Kong (HKU17305914P, HKU705513P), the Croucher Foundation, and the HKU OYRA and ROP.

Importance of factors determining the effective lifetime of a mass, long-lasting, insecticidal net distribution: a sensitivity analysis

PubMed Central

2012-01-01

Background Long-lasting insecticidal nets (LLINs) reduce malaria transmission by protecting individuals from infectious bites, and by reducing mosquito survival. In recent years, millions of LLINs have been distributed across sub-Saharan Africa (SSA). Over time, LLINs decay physically and chemically and are destroyed, making repeated interventions necessary to prevent a resurgence of malaria. Because its effects on transmission are important (more so than the effects of individual protection), estimates of the lifetime of mass distribution rounds should be based on the effective length of epidemiological protection. Methods Simulation models, parameterised using available field data, were used to analyse how the distribution's effective lifetime depends on the transmission setting and on LLIN characteristics. Factors considered were the pre-intervention transmission level, initial coverage, net attrition, and both physical and chemical decay. An ensemble of 14 stochastic individual-based model variants for malaria in humans was used, combined with a deterministic model for malaria in mosquitoes. Results The effective lifetime was most sensitive to the pre-intervention transmission level, with a lifetime of almost 10 years at an entomological inoculation rate of two infectious bites per adult per annum (ibpapa), but of little more than 2 years at 256 ibpapa. The LLIN attrition rate and the insecticide decay rate were the next most important parameters. The lifetime was surprisingly insensitive to physical decay parameters, but this could change as physical integrity gains importance with the emergence and spread of pyrethroid resistance. Conclusions The strong dependency of the effective lifetime on the pre-intervention transmission level indicated that the required distribution frequency may vary more with the local entomological situation than with LLIN quality or the characteristics of the distribution system. This highlights the need for malaria monitoring both before and during intervention programmes, particularly since there are likely to be strong variations between years and over short distances. The majority of SSA's population falls into exposure categories where the lifetime is relatively long, but because exposure estimates are highly uncertain, it is necessary to consider subsequent interventions before the end of the expected effective lifetime based on an imprecise transmission measure. PMID:22244509

Importance of factors determining the effective lifetime of a mass, long-lasting, insecticidal net distribution: a sensitivity analysis.

PubMed

Briët, Olivier J T; Hardy, Diggory; Smith, Thomas A

2012-01-13

Long-lasting insecticidal nets (LLINs) reduce malaria transmission by protecting individuals from infectious bites, and by reducing mosquito survival. In recent years, millions of LLINs have been distributed across sub-Saharan Africa (SSA). Over time, LLINs decay physically and chemically and are destroyed, making repeated interventions necessary to prevent a resurgence of malaria. Because its effects on transmission are important (more so than the effects of individual protection), estimates of the lifetime of mass distribution rounds should be based on the effective length of epidemiological protection. Simulation models, parameterised using available field data, were used to analyse how the distribution's effective lifetime depends on the transmission setting and on LLIN characteristics. Factors considered were the pre-intervention transmission level, initial coverage, net attrition, and both physical and chemical decay. An ensemble of 14 stochastic individual-based model variants for malaria in humans was used, combined with a deterministic model for malaria in mosquitoes. The effective lifetime was most sensitive to the pre-intervention transmission level, with a lifetime of almost 10 years at an entomological inoculation rate of two infectious bites per adult per annum (ibpapa), but of little more than 2 years at 256 ibpapa. The LLIN attrition rate and the insecticide decay rate were the next most important parameters. The lifetime was surprisingly insensitive to physical decay parameters, but this could change as physical integrity gains importance with the emergence and spread of pyrethroid resistance. The strong dependency of the effective lifetime on the pre-intervention transmission level indicated that the required distribution frequency may vary more with the local entomological situation than with LLIN quality or the characteristics of the distribution system. This highlights the need for malaria monitoring both before and during intervention programmes, particularly since there are likely to be strong variations between years and over short distances. The majority of SSA's population falls into exposure categories where the lifetime is relatively long, but because exposure estimates are highly uncertain, it is necessary to consider subsequent interventions before the end of the expected effective lifetime based on an imprecise transmission measure.

Electrical and Thermal Transport in Inhomogeneous Luttinger Liquids

DOE PAGES

DeGottardi, Wade; Matveev, K. A.

2015-06-12

In this paper, we study the transport properties of long quantum wires by generalizing the Luttinger liquid approach to allow for the finite lifetime of the bosonic excitations. Our theory accounts for long-range disorder and strong electron interactions, both of which are common features of experiments with quantum wires. We obtain the electrical and thermal resistances and thermoelectric properties of such quantum wires and find a strong deviation from perfect conductance quantization. Finally, we cast our results in terms of the thermal conductivity and bulk viscosity of the electron liquid and give the temperature scale above which the transport canmore » be described by classical hydrodynamics.« less

Remnants of semiclassical bistability in the few-photon regime of cavity QED.

PubMed

Kerckhoff, Joseph; Armen, Michael A; Mabuchi, Hideo

2011-11-21

Broadband homodyne detection of the light transmitted by a Fabry-Perot cavity containing a strongly-coupled (133)Cs atom is used to probe the dynamic optical response in a regime where semiclassical theory predicts bistability but strong quantum corrections should apply. While quantum fluctuations destabilize true equilibrium bistability, our observations confirm the existence of metastable states with finite lifetimes and a hysteretic response is apparent when the optical drive is modulated on comparable timescales. Our experiment elucidates remnant semiclassical behavior in the attojoule (~10 photon) regime of single-atom cavity QED, of potential significance for ultra-low power photonic signal processing. © 2011 Optical Society of America

Fluorescence Lifetime Imaging Microscopy (FLIM) of quantum dots in living cells

NASA Astrophysics Data System (ADS)

Nadeau, Jay; Carlini, Lina

2013-02-01

Fluorescence lifetime imaging microscopy (FLIM) is an emerging imaging technique that can indicate environmental factors such as pH and redox potential by the effect of these factors on the fluorescence lifetimes of fluorophores. Semiconductor quantum dots (QDs) are highly sensitive to environment and so are ideal for use in FLIM, although certain experimental parameters must be carefully considered for QD imaging to account for their long lifetimes and two-photon behavior. We image the uptake of three types of QDs in cultured fibroblasts and show some preliminary results on the effects of endosomes and lysosomes on QD lifetimes. These results indicate the feasibility of FLIM for studies using QDs in live cells.

Positron lifetime calculation for the elements of the periodic table.

PubMed

Campillo Robles, J M; Ogando, E; Plazaola, F

2007-04-30

Theoretical positron lifetime values have been calculated systematically for most of the elements of the periodic table. Self-consistent and non-self-consistent schemes have been used for the calculation of the electronic structure in the solid, as well as different parametrizations for the positron enhancement factor and correlation energy. The results obtained have been studied and compared with experimental data, confirming the theoretical trends. As is known, positron lifetimes in bulk show a periodic behaviour with atomic number. These calculations also confirm that monovacancy lifetimes follow the same behaviour. The effects of enhancement factors used in calculations have been commented upon. Finally, we have analysed the effects that f and d electrons have on positron lifetimes.

Prediction of dynamic strains on a monopile offshore wind turbine using virtual sensors

NASA Astrophysics Data System (ADS)

Iliopoulos, A. N.; Weijtjens, W.; Van Hemelrijck, D.; Devriendt, C.

2015-07-01

The monitoring of the condition of the offshore wind turbine during its operational states offers the possibility of performing accurate assessments of the remaining life-time as well as supporting maintenance decisions during its entire life. The efficacy of structural monitoring in the case of the offshore wind turbine, though, is undermined by the practical limitations connected to the measurement system in terms of cost, weight and feasibility of sensor mounting (e.g. at muddline level 30m below the water level). This limitation is overcome by reconstructing the full-field response of the structure based on the limited number of measured accelerations and a calibrated Finite Element Model of the system. A modal decomposition and expansion approach is used for reconstructing the responses at all degrees of freedom of the finite element model. The paper will demonstrate the possibility to predict dynamic strains from acceleration measurements based on the aforementioned methodology. These virtual dynamic strains will then be evaluated and validated based on actual strain measurements obtained from a monitoring campaign on an offshore Vestas V90 3 MW wind turbine on a monopile foundation.

Creep Life Prediction of Ceramic Components Using the Finite Element Based Integrated Design Program (CARES/Creep)

NASA Technical Reports Server (NTRS)

Jadaan, Osama M.; Powers, Lynn M.; Gyekenyesi, John P.

1997-01-01

The desirable properties of ceramics at high temperatures have generated interest in their use for structural applications such as in advanced turbine systems. Design lives for such systems can exceed 10,000 hours. Such long life requirements necessitate subjecting the components to relatively low stresses. The combination of high temperatures and low stresses typically places failure for monolithic ceramics in the creep regime. The objective of this work is to present a design methodology for predicting the lifetimes of structural components subjected to multiaxial creep loading. This methodology utilizes commercially available finite element packages and takes into account the time varying creep stress distributions (stress relaxation). In this methodology, the creep life of a component is divided into short time steps, during which, the stress and strain distributions are assumed constant. The damage, D, is calculated for each time step based on a modified Monkman-Grant creep rupture criterion. For components subjected to predominantly tensile loading, failure is assumed to occur when the normalized accumulated damage at any point in the component is greater than or equal to unity.

Nonequilibrium quantum mechanics: A "hot quantum soup" of paramagnons

NASA Astrophysics Data System (ADS)

Scammell, H. D.; Sushkov, O. P.

2017-01-01

Motivated by recent measurements of the lifetime (decay width) of paramagnons in quantum antiferromagnet TlCuCl3, we investigate paramagnon decay in a heat bath and formulate an appropriate quantum theory. Our formulation can be split into two regimes: (i) a nonperturbative, "hot quantum soup" regime where the paramagnon width is comparable to its energy; (ii) a usual perturbative regime where the paramagnon width is significantly lower than its energy. Close to the Neel temperature, the paramagnon width becomes comparable to its energy and falls into the hot quantum soup regime. To describe this regime, we develop a new finite frequency, finite temperature technique for a nonlinear quantum field theory; the "golden rule of quantum kinetics." The formulation is generic and applicable to any three-dimensional quantum antiferromagnet in the vicinity of a quantum critical point. Specifically, we apply our results to TlCuCl3 and find agreement with experimental data. Additionally, we show that logarithmic running of the coupling constant in the upper critical dimension changes the commonly accepted picture of the quantum disordered and quantum critical regimes.

Coupled field-structural analysis of HGTR fuel brick using ABAQUS

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

Mohanty, S.; Jain, R.; Majumdar, S.

2012-07-01

High-temperature, gas-cooled reactors (HTGRs) are usually helium-gas cooled, with a graphite core that can operate at reactor outlet temperatures much higher than can conventional light water reactors. In HTGRs, graphite components moderate and reflect neutrons. During reactor operation, high temperature and high irradiation cause damage to the graphite crystal and grains and create other defects. This cumulative structural damage during the reactor lifetime leads to changes in graphite properties, which can alter the ability to support the designed loads. The aim of the present research is to develop a finite-element code using commercially available ABAQUS software for the structural integritymore » analysis of graphite core components under extreme temperature and irradiation conditions. In addition, the Reactor Geometry Generator tool-kit, developed at Argonne National Laboratory, is used to generate finite-element mesh for complex geometries such as fuel bricks with multiple pin holes and coolant flow channels. This paper presents the proposed concept and discusses results of stress analysis simulations of a fuel block with H-451 grade material properties. (authors)« less

A Coupled Soil-Atmosphere Model of H2O2 on Mars

NASA Technical Reports Server (NTRS)

Bullock, Mark A.; Stoker, Carol R.; Mckay, Christopher P.; Zent, Aaron P.

1994-01-01

The Viking Gas Chromatograph Mass Spectrometer failed to detect organic compounds on Mars, and both the Viking Labeled Release and the Viking Gas Exchange experiments indicated a reactive soil surface. These results have led to the widespread belief that there are oxidants in the martian soil. Since H2O2 is produced by photochemical processes in the atmosphere of Mars, and has been shown in the laboratory to reproduce closely the Viking LR results, it is a likely candidate for a martian soil oxidant. Here, we report on the results of a coupled soil/atmosphere transport model for H202 on Mars. Upon diffusing into the soil, its concentration is determined by the extent to which it is adsorbed and by the rate at which it is catalytically destroyed. An analytical model for calculating the distribution of H202 in the martian atmosphere and soil is developed. The concentration of H202 in the soil is shown to go to zero at a finite depth, a consequence of the nonlinear soil diffusion equation. The model is parameterized in terms of an unknown quantity, the lifetime of H202 against heterogeneous catalytic destruction in the soil. Calculated concentrations are compared with a H202 concentration of 30 nmoles/cu cm, inferred from the Viking Labeled Release experiment. A significant result of this model is that for a wide range of H202 lifetimes (up to 105 years), the extinction depth was found to be less than 3 m. The maximum possible concentration in the top 4 cm is calculated to be approx. 240 nmoles/cu cm, achieved with lifetimes of greater than 1000 years. Concentrations higher than 30 nmoles/cu cm require lifetimes of greater than 4.3 terrestrial years. For a wide range of H202 lifetimes, it was found that the atmospheric concentration is only weakly coupled with soil loss processes. Losses to the soil become significant only when lifetimes are less than a few hours. If there are depths below which H202 is not transported, it is plausible that organic compounds, protected from an oxidizing environment, may still exist. They would have been deposited by meteors, or be the organic remains of past life.

Modeling the Unites States government's economic cost of noise-induced hearing loss for a military population.

PubMed

Tufts, Jennifer B; Weathersby, Paul K; Rodriguez, Francisco A

2010-05-01

The purpose of this paper is to demonstrate the feasibility and utility of developing economic cost models for noise-induced hearing loss (NIHL). First, we outline an economic model of NIHL for a population of US Navy sailors with an "industrial"-type noise exposure. Next, we describe the effect on NIHL-related cost of varying the two central model inputs--the noise-exposure level and the duration of exposure. Such an analysis can help prioritize promising areas, to which limited resources to reduce NIHL-related costs should be devoted. NIHL-related costs borne by the US government were computed on a yearly basis using a finite element approach that took into account varying levels of susceptibility to NIHL. Predicted hearing thresholds for the population were computed with ANSI S3.44-1996 and then used as the basis for the calculation of NIHL-related costs. Annual and cumulative costs were tracked. Noise-exposure level and duration were systematically varied to determine their effects on the expected lifetime NIHL-related cost of a specific US Navy sailor population. Our nominal noise-exposure case [93 dB(A) for six years] yielded a total expected lifetime cost of US $13,472 per sailor, with plausible lower and upper bounds of US $2,500 and US $26,000. Starting with the nominal case, a decrease of 50% in exposure level or duration would yield cost savings of approximately 23% and 19%, respectively. We concluded that a reduction in noise level would be more somewhat more cost-effective than the same percentage reduction in years of exposure. Our economic cost model can be used to estimate the changes in NIHL-related costs that would result from changes in noise-exposure level and/or duration for a single military population. Although the model is limited at present, suggestions are provided for adapting it to civilian populations.

The influence of parental divorce and alcohol abuse on adult offspring risk of lifetime suicide attempt in the United States.

PubMed

Alonzo, Dana; Thompson, Ronald G; Stohl, Mahlki; Hasin, Deborah

2014-05-01

The influences of parental divorce and alcohol abuse on adult offspring lifetime suicide attempt have not been examined in national data. This study analyzed data from the 2001-2002 NESARC to estimate main and interaction effects of parental divorce and alcohol abuse on lifetime suicide attempt. Adjusted for controls, parental divorce and parental alcohol abuse independently increased odds of lifetime suicide attempt. The effect of parental divorce was not significantly moderated by parental alcohol abuse. Further research is needed to examine whether additional parental and offspring psychiatric and substance use covariates attenuate the association between parental divorce and lifetime suicide attempt. PsycINFO Database Record (c) 2014 APA, all rights reserved

26 CFR 1.25A-4 - Lifetime Learning Credit.

Code of Federal Regulations, 2013 CFR

2013-04-01

... qualified tuition and related expenses for purposes of the Lifetime Learning Credit. (d) Effective date. The... 26 Internal Revenue 1 2013-04-01 2013-04-01 false Lifetime Learning Credit. 1.25A-4 Section 1.25A... Changes in Rates During A Taxable Year § 1.25A-4 Lifetime Learning Credit. (a) Amount of the credit—(1...

26 CFR 1.25A-4 - Lifetime Learning Credit.

Code of Federal Regulations, 2014 CFR

2014-04-01

... qualified tuition and related expenses for purposes of the Lifetime Learning Credit. (d) Effective date. The... 26 Internal Revenue 1 2014-04-01 2013-04-01 true Lifetime Learning Credit. 1.25A-4 Section 1.25A-4... Rates During A Taxable Year § 1.25A-4 Lifetime Learning Credit. (a) Amount of the credit—(1) Taxable...

26 CFR 1.25A-4 - Lifetime Learning Credit.

Code of Federal Regulations, 2011 CFR

2011-04-01

... qualified tuition and related expenses for purposes of the Lifetime Learning Credit. (d) Effective date. The... 26 Internal Revenue 1 2011-04-01 2009-04-01 true Lifetime Learning Credit. 1.25A-4 Section 1.25A-4... Rates During A Taxable Year § 1.25A-4 Lifetime Learning Credit. (a) Amount of the credit—(1) Taxable...

26 CFR 1.25A-4 - Lifetime Learning Credit.

Code of Federal Regulations, 2012 CFR

2012-04-01

... qualified tuition and related expenses for purposes of the Lifetime Learning Credit. (d) Effective date. The... 26 Internal Revenue 1 2012-04-01 2012-04-01 false Lifetime Learning Credit. 1.25A-4 Section 1.25A... Changes in Rates During A Taxable Year § 1.25A-4 Lifetime Learning Credit. (a) Amount of the credit—(1...

Low lifetime stress exposure is associated with reduced stimulus–response memory

PubMed Central

Goldfarb, Elizabeth V.; Shields, Grant S.; Daw, Nathaniel D.; Slavich, George M.; Phelps, Elizabeth A.

2017-01-01

Exposure to stress throughout life can cumulatively influence later health, even among young adults. The negative effects of high cumulative stress exposure are well-known, and a shift from episodic to stimulus–response memory has been proposed to underlie forms of psychopathology that are related to high lifetime stress. At the other extreme, effects of very low stress exposure are mixed, with some studies reporting that low stress leads to better outcomes, while others demonstrate that low stress is associated with diminished resilience and negative outcomes. However, the influence of very low lifetime stress exposure on episodic and stimulus–response memory is unknown. Here we use a lifetime stress assessment system (STRAIN) to assess cumulative lifetime stress exposure and measure memory performance in young adults reporting very low and moderate levels of lifetime stress exposure. Relative to moderate levels of stress, very low levels of lifetime stress were associated with reduced use and retention (24 h later) of stimulus–response (SR) associations, and a higher likelihood of using context memory. Further, computational modeling revealed that participants with low levels of stress exhibited worse expression of memory for SR associations than those with moderate stress. These results demonstrate that very low levels of stress exposure can have negative effects on cognition. PMID:28298555

Childhood risk factors for alcohol abuse and psychological distress among adult lesbians.

PubMed

Hughes, Tonda L; Johnson, Timothy P; Wilsnack, Sharon C; Szalacha, Laura A

2007-07-01

This study examined the relationships between childhood and family background variables, including sexual and physical abuse, and subsequent alcohol abuse and psychological distress in adult lesbians. Structural equation modeling was used to evaluate relationships between childhood sexual and physical abuse and parenting variables and latent measures of lifetime alcohol abuse and psychological distress in a large community-based sample of lesbians. Childhood sexual abuse (CSA) directly predicted lifetime alcohol abuse, and childhood physical abuse (CPA) directly predicted lifetime psychological distress. In addition, CSA indirectly increased the risk of lifetime alcohol abuse through its negative effect on age at first heterosexual intercourse. Childhood physical abuse had only indirect effects on lifetime alcohol abuse through its strong relationship to lifetime psychological distress. Parental drinking problems and parental strictness directly predicted lifetime psychological distress; parental drinking problems indirectly predicted lifetime alcohol abuse through the mediators of age of drinking onset and lifetime psychological distress. White lesbians, younger lesbians, and those with lower levels of education were at greatest risk of psychological distress. While the cross-sectional design precludes causal conclusions, study findings--especially those related to CSA--are consistent with previous research on predominantly heterosexual women in the general population. Lesbians who experienced CSA were at heightened risk of lifetime alcohol abuse and those who experienced CPA were at heightened risk of lifetime psychological distress relative to lesbians without abuse histories. Given the dearth of research on childhood abuse and sexual orientation, studies are needed that examine the similarities and differences between lesbians' and heterosexual women's experiences of, and responses to, childhood abuse.

Lubrication model for evaporation of binary sessile drops

NASA Astrophysics Data System (ADS)

Williams, Adam; Sáenz, Pedro; Karapetsas, George; Matar, Omar; Sefiane, Khellil; Valluri, Prashant

2017-11-01

Evaporation of a binary mixture sessile drop from a solid substrate is a highly dynamic and complex process with flow driven both thermal and solutal Marangoni stresses. Experiments on ethanol/water drops have identified chaotic regimes on both the surface and interior of the droplet, while mixture composition has also been seen to govern drop wettability. Using a lubrication-type approach, we present a finite element model for the evaporation of an axisymmetric binary drop deposited on a heated substrate. We consider a thin drop with a moving contact line, taking also into account the commonly ignored effects of inertia which drives interfacial instability. We derive evolution equations for the film height, the temperature and the concentration field considering that the mixture comprises two ideally mixed volatile components with a surface tension linearly dependent on both temperature and concentration. The properties of the mixture such as viscosity also vary locally with concentration. We explore the parameter space to examine the resultant effects on wetting and evaporation where we find qualitative agreement with experiments in both these areas. This enables us to understand the nature of the instabilities that spontaneously emerge over the drop lifetime. EPSRC - EP/K00963X/1.

Controllable bioeffects of laser-generated intracellular microbubbles

NASA Astrophysics Data System (ADS)

Zohdy, Marwa Joy

Laser-induced optical breakdown (LIOB) is a nonlinear energy absorption process that can generate precise damage in biological tissues. With femtosecond laser pulses, disruption is highly localized with minimal thermal and mechanical effects to the surrounding region. Cavitation bubbles are produced as a result of LIOB, and these bubbles can be detected and monitored with high-frequency ultrasound. In this work, the controllable viability effects of LIOB bubbles in single cells were characterized. Using a high-frequency acoustic transducer synchronized with a 793 nm, 100 fs laser pulsed at 250 kHz, thermal effects in the vicinity of an LIOB event were directly assessed. Temperaturedependent pulse-echo displacements were calculated using phase-sensitive correlation tracking and fit to a finite-element heat transfer model to estimate thermal distribution. Results indicate a minimal temperature increase (<1 degree C) within 100 microns of a bubble created with multiple laser pulses, confirming that LIOB can be controlled to be thermally noninvasive in the bubble vicinity. Acoustically detectable microbubbles were generated in individual cells with femtosecond LIOB. By adjusting laser fluence, exposure time, and focal location, LIOB could be controlled to produce distinctly different cellular effects. Small (1-2 micron) bubbles with short lifetimes (10100 ms) could be generated in cells without affecting their viability; and, alternatively, large (510 micron) bubbles with long lifetimes (1-5 s) could be generated for selective cell killing without affecting immediately neighboring cells. Experiments were performed in Chinese hamster ovary (CHO) cells in vitro, and LIOB was detected with both optical and acoustic microscopy. A long-term proliferation assay was also performed using green-fluorescent MCA207 mouse sarcoma cells targeted for LIOB. This assay confirmed that nondestructive bubbles did not affect target cell proliferation over several generations, and that destructive bubbles could indeed eliminate target cells and prevent further proliferation with no effect on immediately neighboring cells. These studies help to outline future applications for site-activated, acoustically monitored intracellular microbubbles. Nondestructive bubbles can potentially be used for functional cell measurements without introducing exogenous agents or affecting subsequent cell proliferation, and destructive bubbles can be used for highly precise biologically-targeted cancer cell therapy with real-time acoustic validation.

Theory of thermionic emission from a two-dimensional conductor and its application to a graphene-semiconductor Schottky junction

NASA Astrophysics Data System (ADS)

Trushin, Maxim

2018-04-01

The standard theory of thermionic emission developed for three-dimensional semiconductors does not apply to two-dimensional materials even for making qualitative predictions because of the vanishing out-of-plane quasiparticle velocity. This study reveals the fundamental origin of the out-of-plane charge carrier motion in a two-dimensional conductor due to the finite quasiparticle lifetime and huge uncertainty of the out-of-plane momentum. The theory is applied to a Schottky junction between graphene and a bulk semiconductor to derive a thermionic constant, which, in contrast to the conventional Richardson constant, is determined by the Schottky barrier height and Fermi level in graphene.

Covariant generalized holographic dark energy and accelerating universe

NASA Astrophysics Data System (ADS)

Nojiri, Shin'ichi; Odintsov, S. D.

2017-08-01

We propose the generalized holographic dark energy model where the infrared cutoff is identified with the combination of the FRW universe parameters: the Hubble rate, particle and future horizons, cosmological constant, the universe lifetime (if finite) and their derivatives. It is demonstrated that with the corresponding choice of the cutoff one can map such holographic dark energy to modified gravity or gravity with a general fluid. Explicitly, F( R) gravity and the general perfect fluid are worked out in detail and the corresponding infrared cutoff is found. Using this correspondence, we get realistic inflation or viable dark energy or a unified inflationary-dark energy universe in terms of covariant holographic dark energy.

Effects of finite volume on the K L – K S mass difference

DOE PAGES

Christ, N.  H.; Feng, X.; Martinelli, G.; ...

2015-06-24

Phenomena that involve two or more on-shell particles are particularly sensitive to the effects of finite volume and require special treatment when computed using lattice QCD. In this paper we generalize the results of Lüscher and Lellouch and Lüscher, which determine the leading-order effects of finite volume on the two-particle spectrum and two-particle decay amplitudes to determine the finite-volume effects in the second-order mixing of the K⁰ and K⁰⁻ states. We extend the methods of Kim, Sachrajda, and Sharpe to provide a direct, uniform treatment of these three, related, finite-volume corrections. In particular, the leading, finite-volume corrections to the Kmore » L – K S mass difference ΔM K and the CP-violating parameter εK are determined, including the potentially large effects which can arise from the near degeneracy of the kaon mass and the energy of a finite-volume, two-pion state.« less

Life test results for an ensemble of CO2 lasers

NASA Technical Reports Server (NTRS)

Peruso, C. J.; Degnan, J. J.; Hochuli, U. E.

1978-01-01

The effects of cathode material, cathode operating temperature, anode configuration, window materials, and hydrogen additives on laser lifetime are determined. Internally oxidized copper and silber-copper alloy cathodes were tested. The cathode operating temperature was raised in some tubes through the use of thermal insulation. Lasers incorporating thermally insulated silver copper oxide cathodes clearly yielded the longest lifetimes-typically in excess of 22,000 hours. The use of platinum sheet versus platinum pin anodes had no observable effect on laser lifetime. Similarly, the choice of germanium, cadmium telluride, or zinc selenide as the optical window material appears to have no impact on lifetime.

Dynamics of submicron aerosol droplets in a robust optical trap formed by multiple Bessel beams

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

Thanopulos, Ioannis; Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens 11635; Luckhaus, David

In this paper, we model the three-dimensional escape dynamics of single submicron-sized aerosol droplets in optical multiple Bessel beam traps. Trapping in counter-propagating Bessel beams (CPBBs) is compared with a newly proposed quadruple Bessel beam (QBB) trap, which consists of two perpendicularly arranged CPBB traps. Calculations are performed for perfectly and imperfectly aligned traps. Mie-theory and finite-difference time-domain methods are used to calculate the optical forces. The droplet escape kinetics are obtained from the solution of the Langevin equation using a Verlet algorithm. Provided the traps are perfectly aligned, the calculations indicate very long lifetimes for droplets trapped either inmore » the CPBB or in the QBB trap. However, minor misalignments that are hard to control experimentally already severely diminish the stability of the CPBB trap. By contrast, such minor misalignments hardly affect the extended droplet lifetimes in a QBB trap. The QBB trap is found to be a stable, robust optical trap, which should enable the experimental investigation of submicron droplets with radii down to 100 nm. Optical binding between two droplets and its potential role in preventing coagulation when loading a CPBB trap is briefly addressed.« less

Weak lasing in one-dimensional polariton superlattices.

PubMed

Zhang, Long; Xie, Wei; Wang, Jian; Poddubny, Alexander; Lu, Jian; Wang, Yinglei; Gu, Jie; Liu, Wenhui; Xu, Dan; Shen, Xuechu; Rubo, Yuri G; Altshuler, Boris L; Kavokin, Alexey V; Chen, Zhanghai

2015-03-31

Bosons with finite lifetime exhibit condensation and lasing when their influx exceeds the lasing threshold determined by the dissipative losses. In general, different one-particle states decay differently, and the bosons are usually assumed to condense in the state with the longest lifetime. Interaction between the bosons partially neglected by such an assumption can smear the lasing threshold into a threshold domain--a stable lasing many-body state exists within certain intervals of the bosonic influxes. This recently described weak lasing regime is formed by the spontaneously symmetry breaking and phase-locking self-organization of bosonic modes, which results in an essentially many-body state with a stable balance between gains and losses. Here we report, to our knowledge, the first observation of the weak lasing phase in a one-dimensional condensate of exciton-polaritons subject to a periodic potential. Real and reciprocal space photoluminescence images demonstrate that the spatial period of the condensate is twice as large as the period of the underlying periodic potential. These experiments are realized at room temperature in a ZnO microwire deposited on a silicon grating. The period doubling takes place at a critical pumping power, whereas at a lower power polariton emission images have the same periodicity as the grating.

Resonance and decay phenomena lead to quantum mechanical time asymmetry

NASA Astrophysics Data System (ADS)

Bohm, A.; Bui, H. V.

2013-04-01

The states (Schrödinger picture) and observables (Heisenberg picture) in the standard quantum theory evolve symmetrically in time, given by the unitary group with time extending over -∞ < t < +∞. This time evolution is a mathematical consequence of the Hilbert space boundary condition for the dynamical differential equations. However, this unitary group evolution violates causality. Moreover, it does not solve an old puzzle of Wigner: How does one describe excited states of atoms which decay exponentially, and how is their lifetime τ related to the Lorentzian width Γ? These question can be answered if one replaces the Hilbert space boundary condition by new, Hardy space boundary conditions. These Hardy space boundary conditions allow for a distinction between states (prepared by a preparation apparatus) and observables (detected by a registration apparatus). The new Hardy space quantum theory is time asymmetric, i.e, the time evolution is given by the semigroup with t0 <= t < +∞, which predicts a finite "beginning of time" t0, where t0 is the ensemble of time at which each individual system has been prepared. The Hardy space axiom also leads to the new prediction: the width Γ and the lifetime τ are exactly related by τ = hslash/Γ.

The Effect of Tic Coated Balls and Stress on the Lubricant Lifetime of a Synthetic Hydrocarbon (pennzane 2001A) Using a Vacuum Spiral Orbit Tribometer

NASA Technical Reports Server (NTRS)

Jansen, Mark J.; Jones, William R., Jr.; Pepper, Stephen V.; Wheeler, Donald R.; Schroeer, Achim; Fluehmann, Freddy; Loewenthal, Stuart H.; Shogrin, Bradley A.

2000-01-01

A vacuum spiral orbit rolling contact tribometer was used to determine effect of varying mean Hertzian stress (1.0, 1.5, 2.0 GPa) and the use of 440C and TiC coated 440C balls on lubricant lifetime of a synthetic hydrocarbon (Pennzane 2001A) on 440C stainless steel. Conditions included 210 rpm, approx. 50 micrograms lubricant, an initial vacuum < 1.3xl0(exp-6) Pa, and room temperature (approx. 23 C). Increasing the mean Hertzian stress resulted in an exponential decrease in lubricant lifetime for both material combinations. Substituting a TiC coated 440C ball showed no increase in lifetime over the 440C ball. The decreasing lifetime with increasing stress level correlated well with energy dissipation calculations.

Multimodel Estimates of Atmospheric Lifetimes of Long-lived Ozone-Depleting Substances: Present and Future

NASA Technical Reports Server (NTRS)

Chipperfield, M. P.; Liang, Q.; Strahan, S. E.; Morgenstern, O.; Dhomse, S. S.; Abraham, N. L.; Archibald, A. T.; Bekki, S.; Braesicke, P.; Di Genova, G.;

Lifetime use of psychiatric medications and cognition at 43years of age in schizophrenia in the Northern Finland Birth Cohort 1966.

PubMed

Hulkko, A P; Murray, G K; Moilanen, J; Haapea, M; Rannikko, I; Jones, P B; Barnett, J H; Huhtaniska, S; Isohanni, M K; Koponen, H; Jääskeläinen, E; Miettunen, J

2017-09-01

Higher lifetime antipsychotic exposure has been associated with poorer cognition in schizophrenia. The cognitive effects of adjunctive psychiatric medications and lifetime trends of antipsychotic use remain largely unclear. We aimed to study how lifetime and current benzodiazepine and antidepressant medications, lifetime trends of antipsychotic use and antipsychotic polypharmacy are associated with cognitive performance in midlife schizophrenia. Sixty participants with DSM-IV schizophrenia from the Northern Finland Birth Cohort 1966 were examined at 43years of age with an extensive cognitive test battery. Cumulative lifetime and current use of psychiatric medications were collected from medical records and interviews. The associations between medication and principal component analysis-based cognitive composite score were analysed using linear regression. Lifetime cumulative DDD years of benzodiazepine and antidepressant medications were not significantly associated with global cognition. Being without antipsychotic medication (for minimum 11months) before the cognitive examination was associated with better cognitive performance (P=0.007) and higher lifetime cumulative DDD years of antipsychotics with poorer cognition (P=0.020), when adjusted for gender, onset age and lifetime hospital treatment days. Other lifetime trends of antipsychotic use, such as a long antipsychotic-free period earlier in the treatment history, and antipsychotic polypharmacy, were not significantly associated with cognition. Based on these naturalistic data, low exposure to adjunctive benzodiazepine and antidepressant medications does not seem to affect cognition nor explain the possible negative effects of high dose long-term antipsychotic medication on cognition in schizophrenia. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Multimodel Estimates of Atmospheric Lifetimes of Long-Lived Ozone-Depleting Substances: Present and Future

NASA Technical Reports Server (NTRS)

Chipperfield, M. P.; Liang, Q.; Strahan, S. E.; Morgenstern, O.; Dhomse, S. S.; Abraham, N. L.; Archibald, A. T.; Bekki, S.; Braesicke, P.; Di Genova, G.;

The atmospheric lifetime of black carbon

NASA Astrophysics Data System (ADS)

Cape, J. N.; Coyle, M.; Dumitrean, P.

2012-11-01

Black carbon (BC) in the atmosphere contributes to the human health effects of particulate matter and contributes to radiative forcing of climate. The lifetime of BC, particularly the smaller particle sizes (PM2.5) which can be transported over long distances, is therefore an important factor in determining the range of such effects, and the spatial footprint of emission controls. Theory and models suggest that the typical lifetime of BC is around one week. The frequency distributions of measurements of a range of hydrocarbons at a remote rural site in southern Scotland (Auchencorth Moss) between 2007 and 2010 have been used to quantify the relationship between atmospheric lifetime and the geometric standard deviation of observed concentration. The analysis relies on an assumed common major emission source for hydrocarbons and BC, namely diesel-engined vehicles. The logarithm of the standard deviation of the log-transformed concentration data is linearly related to hydrocarbon lifetime, and the same statistic for BC can be used to assess the lifetime of BC relative to the hydrocarbons. Annual average data show BC lifetimes in the range 4-12 days, for an assumed OH concentration of 7 × 105 cm-3. At this site there is little difference in BC lifetime between winter and summer, despite a 3-fold difference in relative hydrocarbon lifetimes. This observation confirms the role of wet deposition as an important removal process for BC, as there is no difference in precipitation between winter and summer at this site. BC lifetime was significantly greater in 2010, which had 23% less rainfall than the preceding 3 years.

Finite Element Simulations of Hard-On-Soft Hip Joint Prosthesis Accounting for Dynamic Loads Calculated from a Musculoskeletal Model during Walking.

PubMed

Ruggiero, Alessandro; Merola, Massimiliano; Affatato, Saverio

2018-04-09

The hip joint replacement is one of the most successful orthopedic surgical procedures although it involves challenges to overcome. The patient group undergoing total hip arthroplasty now includes younger and more active patients who require a broad range of motion and a longer service lifetime for the replacement joint. It is well known that wear tests have a long duration and they are very expensive, thus studying the effects of geometry, loading, or alignment perturbations may be performed by Finite Element Analysis. The aim of the study was to evaluate total deformation and stress intensity on ultra-high molecular weight polyethylene liner coupled with hard material head during one step. Moving toward in-silico wear assessment of implants, in the presented simulations we used a musculoskeletal multibody model of a human body giving the loading and relative kinematic of the investigated tribo-system during the gait. The analysis compared two frictional conditions -dry and wet and two geometrical cases- with and without radial clearance. The loads and rotations followed the variability of the gait cycle as well as stress/strain acting in the UHWMPE cup. The obtained results allowed collection of the complete stress/strain description of the polyethylene cup during the gait and calculation of the maximum contact pressure on the lateral edge of the insert. The tensional state resulted in being more influenced by the geometrical conditions in terms of radial clearance than by the variation of the friction coefficients due to lubrication phenomena.

Creep Life of Ceramic Components Using a Finite-Element-Based Integrated Design Program (CARES/CREEP)

NASA Technical Reports Server (NTRS)

Powers, L. M.; Jadaan, O. M.; Gyekenyesi, J. P.

1998-01-01

The desirable properties of ceramics at high temperatures have generated interest in their use for structural application such as in advanced turbine engine systems. Design lives for such systems can exceed 10,000 hours. The long life requirement necessitates subjecting the components to relatively low stresses. The combination of high temperatures and low stresses typically places failure for monolithic ceramics in the creep regime. The objective of this paper is to present a design methodology for predicting the lifetimes of structural components subjected to creep rupture conditions. This methodology utilizes commercially available finite element packages and takes into account the time-varying creep strain distributions (stress relaxation). The creep life, of a component is discretized into short time steps, during which the stress and strain distributions are assumed constant. The damage is calculated for each time step based on a modified Monkman-Grant creep rupture criterion. Failure is assumed to occur when the normalized accumulated damage at any point in the component is greater than or equal to unity. The corresponding time will be the creep rupture life for that component. Examples are chosen to demonstrate the Ceramics Analysis and Reliability Evaluation of Structures/CREEP (CARES/CREEP) integrated design program, which is written for the ANSYS finite element package. Depending on the component size and loading conditions, it was found that in real structures one of two competing failure modes (creep or slow crack growth) will dominate. Applications to benchmark problems and engine components are included.

Creep Life of Ceramic Components Using a Finite-Element-Based Integrated Design Program (CARES/CREEP)

NASA Technical Reports Server (NTRS)

Gyekenyesi, J. P.; Powers, L. M.; Jadaan, O. M.

1998-01-01

The desirable properties of ceramics at high temperatures have generated interest in their use for structural applications such as in advanced turbine systems. Design lives for such systems can exceed 10,000 hours. The long life requirement necessitates subjecting the components to relatively low stresses. The combination of high temperatures and low stresses typically places failure for monolithic ceramics in the creep regime. The objective of this paper is to present a design methodology for predicting the lifetimes of structural components subjected to creep rupture conditions. This methodology utilized commercially available finite element packages and takes into account the time-varying creep strain distributions (stress relaxation). The creep life of a component is discretized into short time steps, during which the stress and strain distributions are assumed constant. The damage is calculated for each time step based on a modified Monkman-Grant creep rupture criterion. Failure is assumed to occur when the normalized accumulated damage at any point in the component is greater than or equal to unity. The corresponding time will be the creep rupture life for that component. Examples are chosen to demonstrate the CARES/CREEP (Ceramics Analysis and Reliability Evaluation of Structures/CREEP) integrated design programs, which is written for the ANSYS finite element package. Depending on the component size and loading conditions, it was found that in real structures one of two competing failure modes (creep or slow crack growth) will dominate. Applications to benechmark problems and engine components are included.

The effect of age at first calving and calving interval on productive life and lifetime profit in korean holsteins.

PubMed

Do, Changhee; Wasana, Nidarshani; Cho, Kwanghyun; Choi, Yunho; Choi, Taejeong; Park, Byungho; Lee, Donghee

2013-11-01

This study was performed to estimate the effect of age at first calving and first two calving intervals on productive life and life time profit in Korean Holsteins. Reproduction data of Korean Holsteins born from 1998 to 2004 and lactation data from 276,573 cows with birth and last dry date that calved between 2000 and 2010 were used for the analysis. Lifetime profit increased with the days of life span. Regression of Life Span on Lifetime profit indicated that there was an increase of 3,800 Won (approximately $3.45) of lifetime profit per day increase in life span. This is evidence that care of each cow is necessary to improve net return and important for farms maintaining profitable cows. The estimates of heritability of age at first calving, first two calving intervals, days in milk for lifetime, lifespan, milk income and lifetime profit were 0.111, 0.088, 0.142, 0.140, 0.143, 0.123, and 0.102, respectively. The low heritabilities indicated that the productive life and economical traits include reproductive and productive characteristics. Age at first calving and interval between first and second calving had negative genetic correlation with lifetime profit (-0.080 and -0.265, respectively). Reducing age at first calving and first calving interval had a positive effect on lifetime profit. Lifetime profit increased to approximately 2,600,000 (2,363.6) from 800,000 Won ($727.3) when age at first calving decreased to (22.3 month) from (32.8 month). Results suggested that reproductive traits such as age at first calving and calving interval might affect various economical traits and consequently influenced productive life and profitability of cows. In conclusion, regard of the age at first calving must be taken with the optimum age at first calving for maximum lifetime profit being 22.5 to 23.5 months. Moreover, considering the negative genetic correlation of first calving interval with lifetime profit, it should be reduced against the present trend of increase.

The Effect of Age at First Calving and Calving Interval on Productive Life and Lifetime Profit in Korean Holsteins

PubMed Central

Do, Changhee; Wasana, Nidarshani; Cho, Kwanghyun; Choi, Yunho; Choi, Taejeong; Park, Byungho; Lee, Donghee

2013-01-01

This study was performed to estimate the effect of age at first calving and first two calving intervals on productive life and life time profit in Korean Holsteins. Reproduction data of Korean Holsteins born from 1998 to 2004 and lactation data from 276,573 cows with birth and last dry date that calved between 2000 and 2010 were used for the analysis. Lifetime profit increased with the days of life span. Regression of Life Span on Lifetime profit indicated that there was an increase of 3,800 Won (approximately $3.45) of lifetime profit per day increase in life span. This is evidence that care of each cow is necessary to improve net return and important for farms maintaining profitable cows. The estimates of heritability of age at first calving, first two calving intervals, days in milk for lifetime, lifespan, milk income and lifetime profit were 0.111, 0.088, 0.142, 0.140, 0.143, 0.123, and 0.102, respectively. The low heritabilities indicated that the productive life and economical traits include reproductive and productive characteristics. Age at first calving and interval between first and second calving had negative genetic correlation with lifetime profit (−0.080 and −0.265, respectively). Reducing age at first calving and first calving interval had a positive effect on lifetime profit. Lifetime profit increased to approximately 2,600,000 (2,363.6) from 800,000 Won ($727.3) when age at first calving decreased to (22.3 month) from (32.8 month). Results suggested that reproductive traits such as age at first calving and calving interval might affect various economical traits and consequently influenced productive life and profitability of cows. In conclusion, regard of the age at first calving must be taken with the optimum age at first calving for maximum lifetime profit being 22.5 to 23.5 months. Moreover, considering the negative genetic correlation of first calving interval with lifetime profit, it should be reduced against the present trend of increase. PMID:25049735

Fatigue failure of dentin-composite disks subjected to cyclic diametral compression

PubMed Central

Li, Yuping; Carrera, Carola; Chen, Ruoqiong; Li, Jianying; Chen, Yungchung; Lenton, Patricia; Rudney, Joel. D.; Jones, Robert S.; Aparicio, Conrado; Fok, Alex

2015-01-01

Objective Our aim was to establish the relationship between cyclic loading and fatigue life of the dentin-composite interface using the newly developed disk in diametral compression tests. The results were then used to estimate the fatigue life of restored teeth under occlusal loading. Methods Disk specimens (5mm dia. × 2mm thick) were prepared using bovine incisors and restored with either a methacrylate-based composite Z100™ with Adper Single Bond Plus (Z100) or silorane-based composite Filtek ™ LS with LS System adhesive (LS). The dentin-composite disks were tested under cyclic diametral compression to determine the number of cycles to failure (Nf) at three load levels (n = 3 per group). Finite element analysis (FEA) was used to calculate the interfacial stresses (σ) within the specimen, to establish the σ vs. Nf curves, and those within a restored tooth under normal chewing forces (15N maximum). These were then used to estimate the lifetime of the restored tooth for the two restorative systems. Results The disks restored with LS had a higher fatigue resistance than those restored with Z100. The maximum interfacial stress in the restored tooth determined by FEA was ∼0.5MPa. Based on the estimate of 300,000 cycles of chewing per year, the predicted lifetime under occlusal loading for teeth restored with LS and Z100 was 33 and 10 years, respectively. Significance The disk in cyclic diametral compression has been used successfully to provide fatigue data which allows the lifetime of composite-restored teeth under occlusal loading to be predicted using numerical simulation. PMID:25958269

Effective delayed neutron fraction and prompt neutron lifetime of Tehran research reactor mixed-core.

PubMed

Lashkari, A; Khalafi, H; Kazeminejad, H

2013-05-01

In this work, kinetic parameters of Tehran research reactor (TRR) mixed cores have been calculated. The mixed core configurations are made by replacement of the low enriched uranium control fuel elements with highly enriched uranium control fuel elements in the reference core. The MTR_PC package, a nuclear reactor analysis tool, is used to perform the analysis. Simulations were carried out to compute effective delayed neutron fraction and prompt neutron lifetime. Calculation of kinetic parameters is necessary for reactivity and power excursion transient analysis. The results of this research show that effective delayed neutron fraction decreases and prompt neutron lifetime increases with the fuels burn-up. Also, by increasing the number of highly enriched uranium control fuel elements in the reference core, the prompt neutron lifetime increases, but effective delayed neutron fraction does not show any considerable change.

Effective delayed neutron fraction and prompt neutron lifetime of Tehran research reactor mixed-core

PubMed Central

Lashkari, A.; Khalafi, H.; Kazeminejad, H.

2013-01-01

In this work, kinetic parameters of Tehran research reactor (TRR) mixed cores have been calculated. The mixed core configurations are made by replacement of the low enriched uranium control fuel elements with highly enriched uranium control fuel elements in the reference core. The MTR_PC package, a nuclear reactor analysis tool, is used to perform the analysis. Simulations were carried out to compute effective delayed neutron fraction and prompt neutron lifetime. Calculation of kinetic parameters is necessary for reactivity and power excursion transient analysis. The results of this research show that effective delayed neutron fraction decreases and prompt neutron lifetime increases with the fuels burn-up. Also, by increasing the number of highly enriched uranium control fuel elements in the reference core, the prompt neutron lifetime increases, but effective delayed neutron fraction does not show any considerable change. PMID:24976672

26 CFR 1.25A-0 - Table of contents.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Credit and Lifetime Learning Credit. (1) In general. (2) Hope Scholarship Credit. (3) Lifetime Learning... conviction. (2) Examples. (e) Academic period for prepayments. (1) In general. (2) Example. (f) Effective date. § 1.25A-4Lifetime Learning Credit (a) Amount of the credit. (1) Taxable years beginning before...

26 CFR 1.25A-0 - Table of contents.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Credit and Lifetime Learning Credit. (1) In general. (2) Hope Scholarship Credit. (3) Lifetime Learning... conviction. (2) Examples. (e) Academic period for prepayments. (1) In general. (2) Example. (f) Effective date. § 1.25A-4Lifetime Learning Credit (a) Amount of the credit. (1) Taxable years beginning before...

26 CFR 1.25A-0 - Table of contents.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Credit and Lifetime Learning Credit. (1) In general. (2) Hope Scholarship Credit. (3) Lifetime Learning... conviction. (2) Examples. (e) Academic period for prepayments. (1) In general. (2) Example. (f) Effective date. § 1.25A-4Lifetime Learning Credit (a) Amount of the credit. (1) Taxable years beginning before...

26 CFR 1.25A-0 - Table of contents.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Credit and Lifetime Learning Credit. (1) In general. (2) Hope Scholarship Credit. (3) Lifetime Learning... conviction. (2) Examples. (e) Academic period for prepayments. (1) In general. (2) Example. (f) Effective date. § 1.25A-4Lifetime Learning Credit (a) Amount of the credit. (1) Taxable years beginning before...

Accelerated lifetime test of vibration isolator made of Metal Rubber material

NASA Astrophysics Data System (ADS)

Ao, Hongrui; Ma, Yong; Wang, Xianbiao; Chen, Jianye; Jiang, Hongyuan

2017-01-01

The Metal Rubber material (MR) is a kind of material with nonlinear damping characteristics for its application in the field of aerospace, petrochemical industry and so on. The study on the lifetime of MR material is impendent to its application in engineering. Based on the dynamic characteristic of MR, the accelerated lifetime experiments of vibration isolators made of MR working under random vibration load were conducted. The effects of structural parameters of MR components on the lifetime of isolators were studied and modelled with the fitting curves of degradation data. The lifetime prediction methods were proposed based on the models.

ORNL Pre-test Analyses of A Large-scale Experiment in STYLE

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

Williams, Paul T; Yin, Shengjun; Klasky, Hilda B

Oak Ridge National Laboratory (ORNL) is conducting a series of numerical analyses to simulate a large scale mock-up experiment planned within the European Network for Structural Integrity for Lifetime Management non-RPV Components (STYLE). STYLE is a European cooperative effort to assess the structural integrity of (non-reactor pressure vessel) reactor coolant pressure boundary components relevant to ageing and life-time management and to integrate the knowledge created in the project into mainstream nuclear industry assessment codes. ORNL contributes work-in-kind support to STYLE Work Package 2 (Numerical Analysis/Advanced Tools) and Work Package 3 (Engineering Assessment Methods/LBB Analyses). This paper summarizes the current statusmore » of ORNL analyses of the STYLE Mock-Up3 large-scale experiment to simulate and evaluate crack growth in a cladded ferritic pipe. The analyses are being performed in two parts. In the first part, advanced fracture mechanics models are being developed and performed to evaluate several experiment designs taking into account the capabilities of the test facility while satisfying the test objectives. Then these advanced fracture mechanics models will be utilized to simulate the crack growth in the large scale mock-up test. For the second part, the recently developed ORNL SIAM-PFM open-source, cross-platform, probabilistic computational tool will be used to generate an alternative assessment for comparison with the advanced fracture mechanics model results. The SIAM-PFM probabilistic analysis of the Mock-Up3 experiment will utilize fracture modules that are installed into a general probabilistic framework. The probabilistic results of the Mock-Up3 experiment obtained from SIAM-PFM will be compared to those results generated using the deterministic 3D nonlinear finite-element modeling approach. The objective of the probabilistic analysis is to provide uncertainty bounds that will assist in assessing the more detailed 3D finite-element solutions and to also assess the level of confidence that can be placed in the best-estimate finiteelement solutions.« less

Experimental determination of quantum-well lifetime effect on large-signal resonant tunneling diode switching time

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

Growden, Tyler A.; Berger, Paul R., E-mail: pberger@ieee.org; Brown, E. R.

An experimental determination is presented of the effect the quantum-well lifetime has on a large-signal resonant tunneling diode (RTD) switching time. Traditional vertical In{sub 0.53}Ga{sub 0.47}As/AlAs RTDs were grown, fabricated, and characterized. The switching time was measured with a high-speed oscilloscope and found to be close to the sum of the calculated RC-limited 10%–90% switching time and the quantum-well quasibound-state lifetime. This method displays experimental evidence that the two intrinsic resonant-tunneling characteristic times act independently, and that the quasibound-state lifetime then serves as a quantum-limit on the large-signal speed of RTDs.

Substrate thermal conductivity effect on heat dissipation and lifetime improvement of organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Chung, Seungjun; Lee, Jae-Hyun; Jeong, Jaewook; Kim, Jang-Joo; Hong, Yongtaek

2009-06-01

We report substrate thermal conductivity effect on heat dissipation and lifetime improvement of organic light-emitting diodes (OLEDs). Heat dissipation behavior of top-emission OLEDs fabricated on silicon, glass, and planarized stainless steel substrates was measured by using an infrared camera. Peak temperature measured from the backside of each substrate was saturated to be 21.4, 64.5, and 40.5 °C, 180 s after the OLED was operated at luminance of 10 000 cd/m2 and 80% luminance lifetime was about 198, 31, and 96 h, respectively. Efficient heat dissipation through the highly thermally conductive substrates reduced temperature increase, resulting in much improved OLED lifetime.

Effects of Lifetime Occupational Pesticide Exposure on Postural Control Among Farmworkers and Non-Farmworkers.

PubMed

Sunwook, Kim; Nussbaum, Maury A; Quandt, Sara A; Laurienti, Paul J; Arcury, Thomas A

2016-02-01

The aim of the study was to assess potential chronic effects of pesticide exposure on postural control, by examining postural balance of farmworkers and non-farmworkers diverse self-reported lifetime exposures. Balance was assessed during quiet upright stance under four experimental conditions (2 visual × 2 cognitive difficulty). Significant differences in baseline balance performance (eyes open without cognitive task) between occupational groups were apparent in postural sway complexity. When adding a cognitive task to the eyes open condition, the influence of lifetime exposure on complexity ratios appeared different between occupational groups. Removing visual information revealed a negative association of lifetime exposure with complexity ratios. Farmworkers and non-farmworkers may use different postural control strategies even when controlling for the level of lifetime pesticide exposure. Long-term exposure can affect somatosensory/vestibular sensory systems and the central processing of sensory information for postural control.

Effects of lifetime occupational pesticide exposure on postural control among farmworkers and non-farmworkers

PubMed Central

Sunwook, Kim; Nussbaum, Maury A.; Quandt, Sara A.; Laurienti, Paul J.; Arcury, Thomas A.

2015-01-01

Objective Assess potential chronic effects of pesticide exposure on postural control, by examining postural balance of farmworkers and non-farmworkers diverse self-reported lifetime exposures. Methods Balance was assessed during quiet upright stance under four experimental conditions (2 visual × 2 cognitive difficulty). Results Significant differences in baseline balance performance (eyes open without cognitive task) between occupational groups were apparent in postural sway complexity. When adding a cognitive task to the eyes open condition, the influence of lifetime exposure on complexity ratios appeared different between occupational groups. Removing visual information revealed a negative association of lifetime exposure with complexity ratios. Conclusions Farmworkers and non-farmworkers may use different postural control strategies even when controlling for the level of lifetime pesticide exposure. Long-term exposure can affect somatosensory/vestibular sensory systems and the central processing of sensory information for postural control. PMID:26849257

Estimating the Reliability of Electronic Parts in High Radiation Fields

NASA Technical Reports Server (NTRS)

Everline, Chester; Clark, Karla; Man, Guy; Rasmussen, Robert; Johnston, Allan; Kohlhase, Charles; Paulos, Todd

2008-01-01

Radiation effects on materials and electronic parts constrain the lifetime of flight systems visiting Europa. Understanding mission lifetime limits is critical to the design and planning of such a mission. Therefore, the operational aspects of radiation dose are a mission success issue. To predict and manage mission lifetime in a high radiation environment, system engineers need capable tools to trade radiation design choices against system design and reliability, and science achievements. Conventional tools and approaches provided past missions with conservative designs without the ability to predict their lifetime beyond the baseline mission.This paper describes a more systematic approach to understanding spacecraft design margin, allowing better prediction of spacecraft lifetime. This is possible because of newly available electronic parts radiation effects statistics and an enhanced spacecraft system reliability methodology. This new approach can be used in conjunction with traditional approaches for mission design. This paper describes the fundamentals of the new methodology.

Effect of surface roughness on contact line dynamics of a thin droplet

NASA Astrophysics Data System (ADS)

Bhattacharjee, Debanik; Soltannia, Babak; Nazaripoor, Hadi; Sadrzadeh, Mohtada

2017-11-01

Any surface possesses inherent roughness. Droplet spreading on a surface is an example of a contact line problem. The tri-phase contact line is prone to stress singularity which can be relieved by using precursor film assumption and disjoining pressure. In this study, an axisymmetric, incompressible, Newtonian droplet spreading on a surface was investigated. An evolution equation which tracks the droplet height over time was obtained considering the lubrication approximation. The nonlinear PDE of evolution equation was solved using finite difference scheme. A simplified Gaussian model was used as a starting point to assess the role of roughness in the dynamics of contact line. The preliminary results revealed that, for both impermeable and permeable surfaces, the apparent contact angle increased in the presence of defects whereas the equilibrium stage remained unaffected. The apparent contact angle, however, was more strongly dependent on the nature and density of defects for impermeable surfaces due to the longer droplet lifetime. Furthermore, random self-affine and non-Gaussian models are employed. The mathematical model results are finally compared with theoretical models like the Cassie-Baxter, Wenzel, and Penetration modes. NSERC.

Transverse and Longitudinal proximity effect

NASA Astrophysics Data System (ADS)

Jalan, Pryianka; Chand, Hum; Srianand, Raghunathan

2018-04-01

With close pairs (˜1.5arcmin) of quasars (QSOs), absorption in the spectra of a background quasar in the vicinity of a foreground quasar can be used to study the environment of the latter quasar at kpc-Mpc scales. For this we used a sample of 205 quasar pairs from the Sloan Digital Sky-Survey Data Release 12 (SDSS DR12) in the redshift range of 2.5 to 3.5 by studying their H I Ly-α absorption. We study the environment of QSOs both in the longitudinal as well as in the transverse direction by carrying out a statistical comparison of the Ly-α absorption lines in the quasar vicinity to that of the absorption lines caused by the inter-galactic medium (IGM). This comparison was done with IGM, matched in absorption redshift and signal-to-noise ratio (SNR) to that of the proximity region. In contrast to the measurements along the line-of-sight, the regions transverse to the quasars exhibit enhanced H I Ly-α absorption. This discrepancy can either be interpreted as due to an anisotropic emission from the quasars or as a consequence of their finite lifetime.

Energy deposition and thermal effects of runaway electrons in ITER-FEAT plasma facing components

NASA Astrophysics Data System (ADS)

Maddaluno, G.; Maruccia, G.; Merola, M.; Rollet, S.

2003-03-01

The profile of energy deposited by runaway electrons (RAEs) of 10 or 50 MeV in International Thermonuclear Experimental Reactor-Fusion Energy Advanced Tokamak (ITER-FEAT) plasma facing components (PFCs) and the subsequent temperature pattern have been calculated by using the Monte Carlo code FLUKA and the finite element heat conduction code ANSYS. The RAE energy deposition density was assumed to be 50 MJ/m 2 and both 10 and 100 ms deposition times were considered. Five different configurations of PFCs were investigated: primary first wall armoured with Be, with and without protecting CFC poloidal limiters, both port limiter first wall options (Be flat tile and CFC monoblock), divertor baffle first wall, armoured with W. The analysis has outlined that for all the configurations but one (port limiter with Be flat tile) the heat sink and the cooling tube beneath the armour are well protected for both RAE energies and for both energy deposition times. On the other hand large melting (W, Be) or sublimation (C) of the surface layer occurs, eventually affecting the PFCs lifetime.

Reliability of Radioisotope Stirling Convertor Linear Alternator

NASA Technical Reports Server (NTRS)

Shah, Ashwin; Korovaichuk, Igor; Geng, Steven M.; Schreiber, Jeffrey G.

2006-01-01

Onboard radioisotope power systems being developed and planned for NASA s deep-space missions would require reliable design lifetimes of up to 14 years. Critical components and materials of Stirling convertors have been undergoing extensive testing and evaluation in support of a reliable performance for the specified life span. Of significant importance to the successful development of the Stirling convertor is the design of a lightweight and highly efficient linear alternator. Alternator performance could vary due to small deviations in the permanent magnet properties, operating temperature, and component geometries. Durability prediction and reliability of the alternator may be affected by these deviations from nominal design conditions. Therefore, it is important to evaluate the effect of these uncertainties in predicting the reliability of the linear alternator performance. This paper presents a study in which a reliability-based methodology is used to assess alternator performance. The response surface characterizing the induced open-circuit voltage performance is constructed using 3-D finite element magnetic analysis. Fast probability integration method is used to determine the probability of the desired performance and its sensitivity to the alternator design parameters.

Nonperturbative Quantum Nature of the Dislocation–Phonon Interaction

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

Li, Mingda; Ding, Zhiwei; Meng, Qingping

Despite the long history of dislocation–phonon interaction studies, there are many problems that have not been fully resolved during this development. These include an incompatibility between a perturbative approach and the long-range nature of a dislocation, the relation between static and dynamic scattering, and their capability of dealing with thermal transport phenomena for bulk material only. Here in this paper, by utilizing a fully quantized dislocation field, which we called a “dislon”, a phonon interacting with a dislocation is renormalized as a quasi-phonon, with shifted quasi-phonon energy, and accompanied by a finite quasi-phonon lifetime, which are reducible to classical results.more » A series of outstanding legacy issues including those above can be directly explained within this unified phonon renormalization approach. For instance, a renormalized phonon naturally resolves the decade-long debate between dynamic and static dislocation–phonon scattering approaches, as two limiting cases. In particular, at nanoscale, both the dynamic and static approaches break down, while the present renormalization approach remains valid by capturing the size effect, showing good agreement with lattice dynamics simulations.« less

Polaritonic Rabi and Josephson Oscillations

PubMed Central

Rahmani, Amir; Laussy, Fabrice P.

2016-01-01

The dynamics of coupled condensates is a wide-encompassing problem with relevance to superconductors, BECs in traps, superfluids, etc. Here, we provide a unified picture of this fundamental problem that includes i) detuning of the free energies, ii) different self-interaction strengths and iii) finite lifetime of the modes. At such, this is particularly relevant for the dynamics of polaritons, both for their internal dynamics between their light and matter constituents, as well as for the more conventional dynamics of two spatially separated condensates. Polaritons are short-lived, interact only through their material fraction and are easily detuned. At such, they bring several variations to their atomic counterpart. We show that the combination of these parameters results in important twists to the phenomenology of the Josephson effect, such as the behaviour of the relative phase (running or oscillating) or the occurence of self-trapping. We undertake a comprehensive stability analysis of the fixed points on a normalized Bloch sphere, that allows us to provide a generalized criterion to identify the Rabi and Josephson regimes in presence of detuning and decay. PMID:27452872

Nonperturbative Quantum Nature of the Dislocation–Phonon Interaction

DOE PAGES

Li, Mingda; Ding, Zhiwei; Meng, Qingping; ...

2017-01-31

Despite the long history of dislocation–phonon interaction studies, there are many problems that have not been fully resolved during this development. These include an incompatibility between a perturbative approach and the long-range nature of a dislocation, the relation between static and dynamic scattering, and their capability of dealing with thermal transport phenomena for bulk material only. Here in this paper, by utilizing a fully quantized dislocation field, which we called a “dislon”, a phonon interacting with a dislocation is renormalized as a quasi-phonon, with shifted quasi-phonon energy, and accompanied by a finite quasi-phonon lifetime, which are reducible to classical results.more » A series of outstanding legacy issues including those above can be directly explained within this unified phonon renormalization approach. For instance, a renormalized phonon naturally resolves the decade-long debate between dynamic and static dislocation–phonon scattering approaches, as two limiting cases. In particular, at nanoscale, both the dynamic and static approaches break down, while the present renormalization approach remains valid by capturing the size effect, showing good agreement with lattice dynamics simulations.« less

Metal-Enhanced Fluorescence from Nanoparticulate Zinc Films

PubMed Central

Aslan, Kadir; Previte, Michael J.R.; Zhang, Yongxia; Geddes, Chris D.

2009-01-01

A detailed study of metal-enhanced fluorescence (MEF) from fluorophores in the blue-to- red spectral region placed in close proximity to thermally evaporated zinc nanostructured films is reported. The zinc nanostructured films were deposited onto glass microscope slides as individual particles and were 1–10 nm in height and 20–100 nm in width, as characterized by Atomic Force Microscopy. The surface plasmon resonance peak of the zinc nanostructured films was ≈ 400 nm. Finite-difference time-domain calculations for single and multiple nanostructures organized in a staggered fashion on a solid support predict, as expected, that the electric fields are concentrated both around and between the nanostructures. Additionally, Mie scattering calculations show that the absorption and scattering components of the extinction spectrum are dominant in the UV and visible spectral ranges, respectively. Enhanced fluorescence emission accompanied by no significant changes in excited state lifetimes of fluorophores with emission wavelengths in the visible blue-to-red spectral range near-to zinc nanostructured films were observed, implying that MEF from zinc nanostructured films is mostly due to an electric field enhancement effect. PMID:19946356

Use of Segregation Indices, Townsend Index, and Air Toxics Data to Assess Lifetime Cancer Risk Disparities in Metropolitan Charleston, South Carolina, USA

PubMed Central

Rice, LaShanta J.; Jiang, Chengsheng; Wilson, Sacoby M.; Burwell-Naney, Kristen; Samantapudi, Ashok; Zhang, Hongmei

2014-01-01

Background: Studies have demonstrated a relationship between segregation and level of education, occupational opportunities, and risk behaviors, yet a paucity of research has elucidated the association between racial residential segregation, socioeconomic deprivation, and lifetime cancer risk. Objectives: We examined estimated lifetime cancer risk from air toxics by racial composition, segregation, and deprivation in census tracts in Metropolitan Charleston. Methods: Segregation indices were used to measure the distribution of groups of people from different races within neighborhoods. The Townsend Index was used to measure economic deprivation in the study area. Poisson multivariate regressions were applied to assess the association of lifetime cancer risk with segregation indices and Townsend Index along with several sociodemographic measures. Results: Lifetime cancer risk from all pollution sources was 28 persons/million for half of the census tracts in Metropolitan Charleston. Isolation Index and Townsend Index both showed significant correlation with lifetime cancer risk from different sources. This significance still holds after adjusting for other sociodemographic measures in a Poisson regression, and these two indices have stronger effect on lifetime cancer risk compared to the effects of sociodemographic measures. Conclusions: We found that material deprivation, measured by the Townsend Index and segregation measured by the Isolation index, introduced high impact on lifetime cancer risk by air toxics at the census tract level. PMID:24852759

Determinants of lifetime reproduction in female brown bears: early body mass, longevity, and hunting regulations.

PubMed

Zedrosser, Andreas; Pelletier, Fanie; Bischof, Richard; Festa-Bianchet, Marco; Swenson, Jon E

2013-01-01

In iteroparous mammals, conditions experienced early in life may have long-lasting effects on lifetime reproductive success. Human-induced mortality is also an important demographic factor in many populations of large mammals and may influence lifetime reproductive success. Here, we explore the effects of early development, population density, and human hunting on survival and lifetime reproductive success in brown bear (Ursus arctos) females, using a 25-year database of individually marked bears in two populations in Sweden. Survival of yearlings to 2 years was not affected by population density or body mass. Yearlings that remained with their mother had higher survival than independent yearlings, partly because regulations prohibit the harvest of bears in family groups. Although mass as a yearling did not affect juvenile survival, it was positively associated with measures of lifetime reproductive success and individual fitness. The majority of adult female brown bear mortality (72%) in our study was due to human causes, mainly hunting, and many females were killed before they reproduced. Therefore, factors allowing females to survive several hunting seasons had a strong positive effect on lifetime reproductive success. We suggest that, in many hunted populations of large mammals, sport harvest is an important influence on both population dynamics and life histories.

Förster resonance energy transfer mediated enhancement of the fluorescence lifetime of organic fluorophores to the millisecond range by coupling to Mn-doped CdS/ZnS quantum dots

NASA Astrophysics Data System (ADS)

Kaiser, Uwe; Sabir, Nadeem; Carrillo-Carrion, Carolina; del Pino, Pablo; Bossi, Mariano; Heimbrodt, Wolfram; Parak, Wolfgang J.

2016-02-01

Manganese-doped CdS/ZnS quantum dots have been used as energy donors in a Förster-like resonance energy transfer (FRET) process to enhance the effective lifetime of organic fluorophores. It was possible to tune the effective lifetime of the fluorophores by about six orders of magnitude from the nanosecond (ns) up to the millisecond (ms) region. Undoped and Mn-doped CdS/ZnS quantum dots functionalized with different dye molecules were selected as a model system for investigating the multiple energy transfer process and the specific interaction between Mn ions and the attached dye molecules. While the lifetime of the free dye molecules was about 5 ns, their linking to undoped CdS/ZnS quantum dots led to a long effective lifetime of about 150 ns, following a non-exponential transient. Manganese-doped core-shell quantum dots further enhanced the long-lasting decay time of the dye to several ms. This opens up a pathway to analyse different fluorophores in the time domain with equal spectral emissions. Such lifetime multiplexing would be an interesting alternative to the commonly used spectral multiplexing in fluorescence detection schemes.

The effect of 17-4PH stainless steel on the lifetime of a Pennzane lubricated Microwave Limb Sounder Antenna Actuator Assembly ball screw for the AURA spacecraft

NASA Astrophysics Data System (ADS)

Jones, William R., Jr.; Jansen, Mark J.; Chen, Gun-Shing; Lam, Jonathan; Balzer, Mark; Lo, John; Anderson, Mark; Schepis, Joseph P.

2005-07-01

During ground based life testing of a Microwave Limb Sounder (MLS) Antenna Actuator Assembly (AAA) ball-screw assembly, lubricant darkening and loss were noted when approximately 10% of required lifetime was completed. The MLS-AAA ball screw and nut are made from 17-4 PH steel, the nut has 440C stainless steel balls, and the assembly is lubricated with a Pennzane formulation containing a three weight percent lead naphthenate additive. Life tests were done in dry nitrogen at 50°C. To investigate the MLS-AAA life test anomaly, Spiral Orbit Tribometer (SOT) accelerated tests were performed. SOT results indicated greatly reduced relative lifetimes of Pennzane formulations in contact with 17-4 PH steel compared to 440C stainless steel. Also, dry nitrogen tests yielded longer relative lifetimes than comparable ultrahigh vacuum tests. Generally, oxidized Pennzane formulations yielded shorter lifetimes than non-oxidized lubricant. This study emphasizes surface chemistry effects on the lubricated lifetime of moving mechanical assemblies.

The Effect of Stress and TiC Coated Balls on Lubricant Lifetimes Using a Vacuum Ball-on-Plate Rolling Contact Tribometer

NASA Technical Reports Server (NTRS)

Jones, William R., Jr.; Jansen, Mark J.; Helmick, Larry H.; Nguyen, QuynhGiao; Wheeler, Donald R.; Boving, Hans J.

1999-01-01

A vacuum ball-on-plate rolling contact tribometer was used to determine the relative lifetimes of a perfluoropolyether (Krytox 143 AC) on 440C stainless steel. The effect of mean Hertzian stresses (0.75, 1.0, 1.5, and 2.0 GPa) and the use of TiC-coated balls on lubricant lifetime was studied. Other conditions included: 100 rpm, 50 micro-g of lubricant, an initial vacuum level of less than 1.0 x 10(exp -8) Torr, and room temperature (23 C). Increasing the mean Hertzian stress from 0.75 to 2.0 GPa results in an exponential decrease in lubricant lifetime for both material combinations. However, substituting a TiC ball for the 440C ball quadrupled lifetime at low stress levels (0.75 and 1.0 GPa) and doubled life at higher stresses (1.5 and 2.0 GPa). The reduced reactivity of the TiC surface with the PFPE lubricant is considered to be the reason for this enhancement. Decreasing lifetime with increasing stress levels correlated well with energy dissipation calculations.

The Effect of 17-4 PH Stainless Steel on the Lifetime of a Pennzane(Trademark) Lubricated Microwave Limb Sounder Antenna Actuator Assembly Ball Screw for the AURA Spacecraft

NASA Technical Reports Server (NTRS)

Jones, William R., Jr.; Jansen, Mark J.; Chen, Gun-Shing; Lam, Jonathan; Balzer, Mark; Anderson, Mark; Lo, John; Schepis, Joseph P.

2005-01-01

During ground based life testing of a Microwave Limb Sounder (MLS) Antenna Actuator Assembly (AAA) ball-screw assembly, lubricant darkening and loss were noted when approximately 10 percent of required lifetime was completed. The MLS-AAA ball screw and nut are made from 17-4 PH steel, the nut has 440C stainless steel balls, and the assembly is lubricated with a Pennzane formulation containing a three weight percent lead naphthenate additive. Life tests were done in dry nitrogen at 50 C. To investigate the MLS-AAA life test anomaly, Spiral Orbit Tribometer (SOT) accelerated tests were performed. SOT results indicated greatly reduced relative lifetimes of Pennzane formulations in contact with 17-4 PH steel compared to 440C stainless steel. Also, dry nitrogen tests yielded longer relative lifetimes than comparable ultrahigh vacuum tests. Generally, oxidized Pennzane formulations yielded shorter lifetimes than non-oxidized lubricant. This study emphasizes surface chemistry effects on the lubricated lifetime of moving mechanical assemblies.

Characterization of Atomic-Layer-Deposited (ALD) Al2O3-Passivated Sub-50-μm-thick Kerf-less Si Wafers by Controlled Spalling

NASA Astrophysics Data System (ADS)

Lee, Yong Hwan; Cha, Hamchorom; Choi, Sunho; Chang, Hyo Sik; Jang, Boyun; Oh, Jihun

2018-05-01

A systematic characterization of sub-50-μm-thick, kerf-less monocrystalline Si wafers fabricated by a controlled fracture method is presented. The spalling process introduces various defects on the Si surface, which result in high surface roughness levels, residual stress, and low effective minority carrier lifetimes. In addition, metals used to induce fracturing in Si diffuse in the Si at room temperature and degrade the effective minority carrier lifetime. Selective removal of these defected Si regions improves the residual stress and effective lifetimes of spalled Si wafers.

Quantum logic between remote quantum registers

NASA Astrophysics Data System (ADS)

Yao, N. Y.; Gong, Z.-X.; Laumann, C. R.; Bennett, S. D.; Duan, L.-M.; Lukin, M. D.; Jiang, L.; Gorshkov, A. V.

2013-02-01

We consider two approaches to dark-spin-mediated quantum computing in hybrid solid-state spin architectures. First, we review the notion of eigenmode-mediated unpolarized spin-chain state transfer and extend the analysis to various experimentally relevant imperfections: quenched disorder, dynamical decoherence, and uncompensated long-range coupling. In finite-length chains, the interplay between disorder-induced localization and decoherence yields a natural optimal channel fidelity, which we calculate. Long-range dipolar couplings induce a finite intrinsic lifetime for the mediating eigenmode; extensive numerical simulations of dipolar chains of lengths up to L=12 show remarkably high fidelity despite these decay processes. We further briefly consider the extension of the protocol to bosonic systems of coupled oscillators. Second, we introduce a quantum mirror based architecture for universal quantum computing that exploits all of the dark spins in the system as potential qubits. While this dramatically increases the number of qubits available, the composite operations required to manipulate dark-spin qubits significantly raise the error threshold for robust operation. Finally, we demonstrate that eigenmode-mediated state transfer can enable robust long-range logic between spatially separated nitrogen-vacancy registers in diamond; disorder-averaged numerics confirm that high-fidelity gates are achievable even in the presence of moderate disorder.

Exponential fading to white of black holes in quantum gravity

NASA Astrophysics Data System (ADS)

Barceló, Carlos; Carballo-Rubio, Raúl; Garay, Luis J.

2017-05-01

Quantization of the gravitational field may allow the existence of a decay channel of black holes into white holes with an explicit time-reversal symmetry. The definition of a meaningful decay probability for this channel is studied in spherically symmetric situations. As a first nontrivial calculation, we present the functional integration over a set of geometries using a single-variable function to interpolate between black-hole and white-hole geometries in a bounded region of spacetime. This computation gives a finite result which depends only on the Schwarzschild mass and a parameter measuring the width of the interpolating region. The associated probability distribution displays an exponential decay law on the latter parameter, with a mean lifetime inversely proportional to the Schwarzschild mass. In physical terms this would imply that matter collapsing to a black hole from a finite radius bounces back elastically and instantaneously, with negligible time delay as measured by external observers. These results invite to reconsider the ultimate nature of astrophysical black holes, providing a possible mechanism for the formation of black stars instead of proper general relativistic black holes. The existence of both this decay channel and black stars can be tested in future observations of gravitational waves.

Dead zone analysis of ECAL barrel modules under static and dynamic load

NASA Astrophysics Data System (ADS)

Pierre-Emile, T.; Anduze, M.

2018-03-01

In the context of ILD project, impact studies of environmental loads on the Electromagnetic CALorimeter (ECAL) have been initiated. The ECAL part considered is the barrel and it consists of several independent modules which are mounted on the Hadronic CALorimeter barrel (HCAL) itself mounted on the cryostat coil and the yoke. The estimate of the gap required between each ECAL modules is fundamental to define the assembly step and avoid mechanical contacts over the barrel lifetime. In the meantime, it has to be done in consideration to the dead spaces reduction and detector hermiticity optimization. Several Finite Element Analysis (FEA) with static and dynamic loads have been performed in order to define correctly the minimum values for those gaps. Due to the implantation site of the whole project in Japan, seismic analysis were carried out in addition to the static ones. This article shows results of these analysis done with the Finite Element Method (FEM) in ANSYS. First results show the impact of HCAL design on the ECAL modules motion in static load. The second study dedicated to seismic approach on a larger model (including yoke and cryostat) gives additional results on earthquake consequences.

Kinetics of Cyclic Oxidation and Cracking and Finite Element Analysis of MA956 and Sapphire/MA956 Composite System

NASA Technical Reports Server (NTRS)

Lee, Kang N.; Arya, Vinod K.; Halford, Gary R.; Barrett, Charles A.

1996-01-01

Sapphire fiber-reinforced MA956 composites hold promise for significant weight savings and increased high-temperature structural capability, as compared to unreinforced MA956. As part of an overall assessment of the high-temperature characteristics of this material system, cyclic oxidation behavior was studied at 1093 C and 1204 C. Initially, both sets of coupons exhibited parabolic oxidation kinetics. Later, monolithic MA956 exhibited spallation and a linear weight loss, whereas the composite showed a linear weight gain without spallation. Weight loss of the monolithic MA956 resulted from the linking of a multiplicity of randomly oriented and closely spaced surface cracks that facilitated ready spallation. By contrast, cracking of the composite's oxide layer was nonintersecting and aligned nominally parallel with the orientation of the subsurface reinforcing fibers. Oxidative lifetime of monolithic MA956 was projected from the observed oxidation kinetics. Linear elastic, finite element continuum, and micromechanics analyses were performed on coupons of the monolithic and composite materials. Results of the analyses qualitatively agreed well with the observed oxide cracking and spallation behavior of both the MA956 and the Sapphire/MA956 composite coupons.

Segmented frequency-domain fluorescence lifetime measurements: minimizing the effects of photobleaching within a multi-component system.

PubMed

Marwani, Hadi M; Lowry, Mark; Keating, Patrick; Warner, Isiah M; Cook, Robert L

2007-11-01

This study introduces a newly developed frequency segmentation and recombination method for frequency-domain fluorescence lifetime measurements to address the effects of changing fractional contributions over time and minimize the effects of photobleaching within multi-component systems. Frequency segmentation and recombination experiments were evaluated using a two component system consisting of fluorescein and rhodamine B. Comparison of experimental data collected in traditional and segmented fashion with simulated data, generated using different changing fractional contributions, demonstrated the validity of the technique. Frequency segmentation and recombination was also applied to a more complex system consisting of pyrene with Suwannee River fulvic acid reference and was shown to improve recovered lifetimes and fractional intensity contributions. It was observed that photobleaching in both systems led to errors in recovered lifetimes which can complicate the interpretation of lifetime results. Results showed clear evidence that the frequency segmentation and recombination method reduced errors resulting from a changing fractional contribution in a multi-component system, and allowed photobleaching issues to be addressed by commercially available instrumentation.

Re-evaluating the Cloud Lifetime Effect: Does Precipitation Suppression Always Lead to an Increased Cloud Extent in Warm Clouds?

NASA Astrophysics Data System (ADS)

Douglas, A.; L'Ecuyer, T.

2017-12-01

Aerosol influences on cloud lifetime remain a poorly understood pathway of aerosol-cloud-radiation interaction with large margins of error according to the fifth IPCC report. Increases in cloud lifetime are attributed to changes in cloud extent due to the suppression of precipitation by increased aerosol concentrations. The dependence of changes in cloud fraction and probability of precipitation on aerosol perturbations for controlled cloud regimes will be investigated using A-Train measurements. CloudSat, MODIS, and AMSR-E measurements from 2006 to 2010 are sorted into regimes established using stability to describe local meteorology, and relative humidity and liquid water path to describe cloud morphology. Holding the thermodynamic and meteorological environments constant allows variations in precipitation and cloud extent owing to regime-specific cloud lifetime effects to be attributed to aerosol perturbations. The relationship between precipitation suppression, cloud extent, and liquid water path will be analyzed. The cloud lifetime effect will be constrained using regimes in the hopes of improving our understanding of precipitation-aerosol interactions.

Effects of substrate voltage on noise characteristics and hole lifetime in SOI metal-oxide-semiconductor field-effect transistor photon detector.

PubMed

Putranto, Dedy Septono Catur; Priambodo, Purnomo Sidi; Hartanto, Djoko; Du, Wei; Satoh, Hiroaki; Ono, Atsushi; Inokawa, Hiroshi

2014-09-08

Low-frequency noise and hole lifetime in silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) are analyzed, considering their use in photon detection based on single-hole counting. The noise becomes minimum at around the transition point between front- and back-channel operations when the substrate voltage is varied, and increases largely on both negative and positive sides of the substrate voltage showing peculiar Lorentzian (generation-recombination) noise spectra. Hole lifetime is evaluated by the analysis of drain current histogram at different substrate voltages. It is found that the peaks in the histogram corresponding to the larger number of stored holes become higher as the substrate bias becomes larger. This can be attributed to the prolonged lifetime caused by the higher electric field inside the body of SOI MOSFET. It can be concluded that, once the inversion channel is induced for detection of the photo-generated holes, the small absolute substrate bias is favorable for short lifetime and low noise, leading to high-speed operation.

Finite-size analysis of continuous-variable measurement-device-independent quantum key distribution

NASA Astrophysics Data System (ADS)

Zhang, Xueying; Zhang, Yichen; Zhao, Yijia; Wang, Xiangyu; Yu, Song; Guo, Hong

2017-10-01

We study the impact of the finite-size effect on the continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) protocol, mainly considering the finite-size effect on the parameter estimation procedure. The central-limit theorem and maximum likelihood estimation theorem are used to estimate the parameters. We also analyze the relationship between the number of exchanged signals and the optimal modulation variance in the protocol. It is proved that when Charlie's position is close to Bob, the CV-MDI QKD protocol has the farthest transmission distance in the finite-size scenario. Finally, we discuss the impact of finite-size effects related to the practical detection in the CV-MDI QKD protocol. The overall results indicate that the finite-size effect has a great influence on the secret-key rate of the CV-MDI QKD protocol and should not be ignored.

Lifetime and diffusion length measurements on silicon material and solar cells

NASA Technical Reports Server (NTRS)

Othmer, S.; Chen, S. C.

1978-01-01

Experimental methods were evaluated for the determination of lifetime and diffusion length in silicon intentionally doped with potentially lifetime-degrading impurities found in metallurgical grade silicon, impurities which may be residual in low-cost silicon intended for use in terrestrial flat-plate arrays. Lifetime measurements were made using a steady-state photoconductivity method. Diffusion length determinations were made using short-circuit current measurements under penetrating illumination. Mutual consistency among all experimental methods was verified, but steady-state photoconductivity was found preferable to photoconductivity decay at short lifetimes and in the presence of traps. The effects of a number of impurities on lifetime in bulk material, and on diffusion length in cells fabricated from this material, were determined. Results are compared with those obtained using different techniques. General agreement was found in terms of the hierarchy of impurities which degrade the lifetime.

Assessing the impacts of lifetime sun exposure on skin damage and skin aging using a non-invasive method.

PubMed

Kimlin, Michael G; Guo, Yuming

2012-05-15

Ultraviolet radiation exposure during an individuals' lifetime is a known risk factor for the development of skin cancer. However, less evidence is available on assessing the relationship between lifetime sun exposure and skin damage and skin aging. This study aims to assess the relationship between lifetime sun exposure and skin damage and skin aging using a non-invasive measure of exposure. We recruited 180 participants (73 males, 107 females) aged 18-83 years. Digital imaging of skin hyperpigmentation (skin damage) and skin wrinkling (skin aging) on the facial region was measured. Lifetime sun exposure (presented as hours) was calculated from the participants' age multiplied by the estimated annual time outdoors for each year of life. We analyzed the effects of lifetime sun exposure on skin damage and skin aging. We adjust for the influence of age, sex, occupation, history of skin cancer, eye color, hair color, and skin color. There were non-linear relationships between lifetime sun exposure and skin damage and skin aging. Younger participant's skin is much more sensitive to sun exposure than those who were over 50 years of age. As such, there were negative interactions between lifetime sun exposure and age. Age had linear effects on skin damage and skin aging. The data presented showed that self reported lifetime sun exposure was positively associated with skin damage and skin aging, in particular, the younger people. Future health promotion for sun exposure needs to pay attention to this group for skin cancer prevention messaging. Copyright © 2012 Elsevier B.V. All rights reserved.

Critical behavior of the contact process in a multiscale network

NASA Astrophysics Data System (ADS)

Ferreira, Silvio C.; Martins, Marcelo L.

2007-09-01

Inspired by dengue and yellow fever epidemics, we investigated the contact process (CP) in a multiscale network constituted by one-dimensional chains connected through a Barabási-Albert scale-free network. In addition to the CP dynamics inside the chains, the exchange of individuals between connected chains (travels) occurs at a constant rate. A finite epidemic threshold and an epidemic mean lifetime diverging exponentially in the subcritical phase, concomitantly with a power law divergence of the outbreak’s duration, were found. A generalized scaling function involving both regular and SF components was proposed for the quasistationary analysis and the associated critical exponents determined, demonstrating that the CP on this hybrid network and nonvanishing travel rates establishes a new universality class.

How old is this bird? The age distribution under some phase sampling schemes.

PubMed

Hautphenne, Sophie; Massaro, Melanie; Taylor, Peter

2017-12-01

In this paper, we use a finite-state continuous-time Markov chain with one absorbing state to model an individual's lifetime. Under this model, the time of death follows a phase-type distribution, and the transient states of the Markov chain are known as phases. We then attempt to provide an answer to the simple question "What is the conditional age distribution of the individual, given its current phase"? We show that the answer depends on how we interpret the question, and in particular, on the phase observation scheme under consideration. We then apply our results to the computation of the age pyramid for the endangered Chatham Island black robin Petroica traversi during the monitoring period 2007-2014.

Time-dependent fiber bundles with local load sharing.

PubMed

Newman, W I; Phoenix, S L

2001-02-01

Fiber bundle models, where fibers have random lifetimes depending on their load histories, are useful tools in explaining time-dependent failure in heterogeneous materials. Such models shed light on diverse phenomena such as fatigue in structural materials and earthquakes in geophysical settings. Various asymptotic and approximate theories have been developed for bundles with various geometries and fiber load-sharing mechanisms, but numerical verification has been hampered by severe computational demands in larger bundles. To gain insight at large size scales, interest has returned to idealized fiber bundle models in 1D. Such simplified models typically assume either equal load sharing (ELS) among survivors, or local load sharing (LLS) where a failed fiber redistributes its load onto its two nearest flanking survivors. Such models can often be solved exactly or asymptotically in increasing bundle size, N, yet still capture the essence of failure in real materials. The present work focuses on 1D bundles under LLS. As in previous works, a fiber has failure rate following a power law in its load level with breakdown exponent rho. Surviving fibers under fixed loads have remaining lifetimes that are independent and exponentially distributed. We develop both new asymptotic theories and new computational algorithms that greatly increase the bundle sizes that can be treated in large replications (e.g., one million fibers in thousands of realizations). In particular we develop an algorithm that adapts several concepts and methods that are well-known among computer scientists, but relatively unknown among physicists, to dramatically increase the computational speed with no attendant loss of accuracy. We consider various regimes of rho that yield drastically different behavior as N increases. For 1/2< or =rho< or =1, ELS and LLS have remarkably similar behavior (they have identical lifetime distributions at rho=1) with approximate Gaussian bundle lifetime statistics and a finite limiting mean. For rho>1 this Gaussian behavior also applies to ELS, whereas LLS behavior diverges sharply showing brittle, weakest volume behavior in terms of characteristic elements derived from critical cluster formation. For 0

Pulsed food resources, but not forest cover, determine lifetime reproductive success in a forest-dwelling rodent.

PubMed

Hoset, Katrine S; Villers, Alexandre; Wistbacka, Ralf; Selonen, Vesa

2017-09-01

The relative contributions of habitat and food availability on fitness may provide evidence for key habitat features needed to safeguard population persistence. However, defining habitat quality for a species can be a complex task, especially if knowledge on the relationship between individual performance and habitat quality is lacking. Here, we determined the relative importance of the availability of suitable forest habitat, body mass and food from masting tree species on female lifetime reproductive success (LRS) of Siberian flying squirrels (Pteromys volans). We calculated LRS of 500 female flying squirrels based on a 22-year-long longitudinal dataset of two populations from western Finland. We assessed with generalised additive models the potential effects of availability of suitable habitat and cumulative lifetime availability of food from masting tree species on female LRS, longevity and fecundity. On a reduced dataset, we evaluated the importance of female winter body mass and conducted a piecewise path analysis to determine how variables were connected. According to generalised additive models female longevity, fecundity and LRS were mainly determined by variation in cumulative lifetime availability of food from masting alder and birch. Instead, habitat and body mass had a smaller role. The path analysis indicated that lifetime food availability had a direct effect on longevity and fecundity, and these had an equal effect on LRS at both study sites. Our results on LRS show that the occurrence of tree masting events during a female flying squirrel's lifetime has a profoundly larger effect on LRS than the cover of suitable forest habitat. Furthermore, this study emphasises the importance of both fecundity and longevity, and the indirect effects of food availability via those components, as determinants of lifetime fitness in female flying squirrels. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

The impact of smoking on expected lifetime with and without chronic disease among Palestinian men in the West Bank.

PubMed

Brønnum-Hansen, Henrik; Jonassen, Marie; Shaheen, Amira; Duraidi, Mohammed; Qalalwa, Khaled; Jeune, Bernard

2018-06-01

The purpose of the study was to estimate life expectancy and the average lifetime with and without chronic disease among male never smokers, ex-smokers and smokers living in the West Bank of the occupied Palestinian territory. The study used a life table for the West Bank male population and Danish relative risk estimates for death for smokers and ex-smokers vs. never smokers and utilized data from the Palestinian Family Survey 2010. Expected lifetime with and without chronic disease was estimated and the contributions from the mortality and the morbidity effect to smoking related difference in average lifetime with and without chronic disease were assessed by decomposition. In the West bank 40% of the male population are smokers. Life expectancy of 15-year-old Palestinian men who would never start smoking was 59.5 years, 41.1 of which were expected to be without chronic disease. Ex-smokers could expect 57.9 years of remaining lifetime, 37.7 years of which without disease. For lifelong heavy smokers (> 20 cigarettes per day), the expected lifetime was reduced to 52.6 years, of which 38.5 years were without chronic disease. Of the total loss of 6.9 years of life expectancy among heavy smokers, the mortality effect accounted for 2.5 years without and 4.4 years with disease, whereas the morbidity effect was negligible. The high prevalence of smoking causes a considerable loss of life years and lifetime without chronic disease. We recommend the Palestinian health authorities to enforce the anti-smoking law.

Effects of hydrogen on majority carrier transport and minority carrier lifetimes in long wavelength infrared HgCdTe on Si

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

Boieriu, P.; Grein, C.H.; Velicu, S.

2006-02-06

We present the results of using an electron cyclotron resonance (ECR) plasma to incorporate hydrogen into long wavelength infrared HgCdTe layers grown by molecular beam epitaxy. Both as-grown and annealed layers doped in situ with indium were hydrogenated. Secondary ion mass spectroscopy confirmed the incorporation of hydrogen. Hall and photoconductive lifetime measurements were used to assess the effects of the hydrogenation. Increases in the electron mobilities and minority carrier lifetimes were observed for almost all ECR conditions.

Frequency domain phosphorescence lifetime Imaging measurements and applications by ISS FastFLIM and multi pulse excitation

NASA Astrophysics Data System (ADS)

Coskun, Ulas C.; Lam, Sandra; Sun, Yuansheng; Liao, Shih-Chu Jeff; George, Steven C.; Barbieri, Beniamino

2017-02-01

Phosphorescence probes can have significantly long lifetimes, on the order of micro- to milli-seconds or longer. In addition, environmental changes can affect the lifetimes of these phosphorescence probes. Thus, Phosphorescence Lifetime Imaging Microscopy (PLIM) is a very useful tool to localize the phosphorescence probes based on their lifetimes to study the variance in the lifetimes due to the micro environmental changes. Since the probes respond to the biologically relevant parameters like oxygen concentration, they can be used to study various biologically relevant processes like cellular metabolism, protein interaction etc. In this case, we study the effects of oxygen on Oxyphor G4 with PLIM. Since The Oxyphor G4 can be quenched by O2, it is a good example of such a probe and has a lifetime around 250us. Here we present the digital frequency domain PLIM technique and study the lifetime of the Oxyphor G4 as a function of the O2 concentration. The lifetime data are successfully presented in a phasor plot for various O2 concentrations and are consistent with the time domain data. Overall, we can analyze the oxygen consumption of varying cells using this technique.

Positron lifetime studies of defect structures in Ba(1-x)K(x)BiO3

NASA Astrophysics Data System (ADS)

Obrien, J. C.; Howell, R. H.; Radousky, H. B.; Sterne, P. A.; Hinks, D. G.; Folkerts, T. J.; Shelton, R. N.

1990-12-01

Temperature-dependent positron lifetime experiments have been performed from room temperature to cryogenic temperatures on Ba(1-x)K(x)BiO3, for x = 0.4 and 0.5. From the temperature dependence of the positron lifetime in the normal state, we observe a clear signature of competition between separate defect populations to trap the positron. Theoretical calculations of lifetimes of free or trapped positrons have been performed on Ba(1-x)K(x)BiO3, to help identify these defects. Lifetime measurements separated by long times have been performed and evidence of aging effects in the sample defect populations is seen in these materials.

Energy Savings Lifetimes and Persistence

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

Hoffman, Ian M.; Schiller, Steven R.; Todd, Annika

2016-02-01

This technical brief explains the concepts of energy savings lifetimes and savings persistence and discusses how program administrators use these factors to calculate savings for efficiency measures, programs and portfolios. Savings lifetime is the length of time that one or more energy efficiency measures or activities save energy, and savings persistence is the change in savings throughout the functional life of a given efficiency measure or activity. Savings lifetimes are essential for assessing the lifecycle benefits and cost effectiveness of efficiency activities and for forecasting loads in resource planning. The brief also provides estimates of savings lifetimes derived from amore » national collection of costs and savings for electric efficiency programs and portfolios.« less

Effects of service condition on rolling contact fatigue failure mechanism and lifetime of thermal spray coatings—A review

NASA Astrophysics Data System (ADS)

Cui, Huawei; Cui, Xiufang; Wang, Haidou; Xing, Zhiguo; Jin, Guo

2015-01-01

The service condition determines the Rolling Contact Fatigue(RCF) failure mechanism and lifetime under ascertain material structure integrity parameter of thermal spray coating. The available literature on the RCF testing of thermal spray coatings under various condition services is considerable; it is generally difficult to synthesize all of the result to obtain a comprehensive understanding of the parameters which has a great effect on a thermal spray coating's resistance of RCF. The effects of service conditions(lubrication states, contact stresses, revolve speed, and slip ratio) on the changing of thermal spray coatings' contact fatigue lifetime is introduced systematically. The effects of different service condition on RCF failure mechanism of thermal spray coating from the change of material structure integrity are also summarized. Moreover, In order to enhance the RCF performance, the parameter optimal design formula of service condition and material structure integrity is proposed based on the effect of service condition on thermal spray coatings' contact fatigue lifetime and RCF failure mechanism. The shortage of available literature and the forecast focus in future researches are discussed based on available research. The explicit result of RCF lifetime law and parameter optimal design formula in term of lubrication states, contact stresses, revolve speed, and slip ratio, is significant to improve the RCF performance on the engineering application.

Estimation of effective dose and lifetime attributable risk from multiple head CT scans in ventriculoperitoneal shunted children.

PubMed

Aw-Zoretic, J; Seth, D; Katzman, G; Sammet, S

2014-10-01

The purpose of this review is to determine the averaged effective dose and lifetime attributable risk factor from multiple head computed tomography (CT) dose data on children with ventriculoperitoneal shunts (VPS). A total of 422 paediatric head CT exams were found between October 2008 and January 2011 and retrospectively reviewed. The CT dose data was weighted with the latest IRCP 103 conversion factor to obtain the effective dose per study and the averaged effective dose was calculated. Estimates of the lifetime attributable risk were also calculated from the averaged effective dose using a conversion factor from the latest BEIR VII report. Our study found the highest effective doses in neonates and the lowest effective doses were observed in the 10-18 years age group. We estimated a 0.007% potential increase risk in neonates and 0.001% potential increased risk in teenagers over the base risk. Multiple head CTs in children equates to a slight potential increase risk in lifetime attributable risk over the baseline risk for cancer, slightly higher in neonates relative to teenagers. The potential risks versus clinical benefit must be assessed. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Analysis of Orbital Lifetime Prediction Parameters in Preparation for Post-Mission Disposal

NASA Astrophysics Data System (ADS)

Choi, Ha-Yeon; Kim, Hae-Dong; Seong, Jae-Dong

2015-12-01

Atmospheric drag force is an important source of perturbation of Low Earth Orbit (LEO) orbit satellites, and solar activity is a major factor for changes in atmospheric density. In particular, the orbital lifetime of a satellite varies with changes in solar activity, so care must be taken in predicting the remaining orbital lifetime during preparation for post-mission disposal. In this paper, the System Tool Kit (STK®) Long-term Orbit Propagator is used to analyze the changes in orbital lifetime predictions with respect to solar activity. In addition, the STK® Lifetime tool is used to analyze the change in orbital lifetime with respect to solar flux data generation, which is needed for the orbital lifetime calculation, and its control on the drag coefficient control. Analysis showed that the application of the most recent solar flux file within the Lifetime tool gives a predicted trend that is closest to the actual orbit. We also examine the effect of the drag coefficient, by performing a comparative analysis between varying and constant coefficients in terms of solar activity intensities.

The relationship between personality, dysfunctional parenting in childhood, and lifetime depression in a sample of employed Japanese adults.

PubMed

Sakado, K; Kuwabara, H; Sato, T; Uehara, T; Sakado, M; Someya, T

2000-10-01

Few studies have explored the relationship between personality, dysfunctional parenting in childhood, and adult depression. Parental rearing styles and personality scores as measured by the Parental Bonding Instrument (PBI) and the Interpersonal Sensitivity Measure (IPSM) were compared in a group of employed Japanese adults with and without a lifetime history of depression. The diagnosis was provided by the Inventory to Diagnose Depression, Lifetime version (IDDL). To estimate the effects of the PBI and the IPSM scores on lifetime depression, a multiple logistic regression analysis was performed. Subjects with lifetime depression were seen to have significantly lower scores on the PBI 'care' and higher scores on the IPSM than the subjects without lifetime depression. Lower levels of maternal care and higher levels of 'interpersonal sensitivity' each independently increased the risk for lifetime depression. The findings of the present study may not be conclusive since the data were retrospectively obtained. Dysfunctional parenting and personality seem to be correlated by lifetime depression, but it is uncertain whether they are independent risk factors

The Impact of a 15-Week Lifetime Wellness Course on Behavior Change and Self-Efficacy in College Students

ERIC Educational Resources Information Center

Lockwood, Park; Wohl, Roy

2012-01-01

Purpose: The purpose of this study was to assess the effectiveness of a lifetime wellness course on changing students' global self-efficacy, physical self-efficacy, and wellness behavior. Methods: Seventy-one college students from a lifetime wellness course completed the TestWell Wellness Inventory--Standard Edition (National Wellness Institute,…

A new method for measuring the neutron lifetime using an in situ neutron detector

DOE PAGES

Morris, Christopher L.; Adamek, Evan Robert; Broussard, Leah Jacklyn; ...

2017-05-30

Here, we describe a new method for measuring surviving neutrons in neutron lifetime measurements using bottled ultracold neutrons (UCN), which provides better characterization of systematic uncertainties and enables higher precision than previous measurement techniques. We also used an active detector that can be lowered into the trap to measure the neutron distribution as a function of height and measure the influence of marginally trapped UCN on the neutron lifetime measurement. Additionally, measurements have demonstrated phase-space evolution and its effect on the lifetime measurement.

A new method for measuring the neutron lifetime using an in situ neutron detector

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

Morris, Christopher L.; Adamek, Evan Robert; Broussard, Leah Jacklyn

Here, we describe a new method for measuring surviving neutrons in neutron lifetime measurements using bottled ultracold neutrons (UCN), which provides better characterization of systematic uncertainties and enables higher precision than previous measurement techniques. We also used an active detector that can be lowered into the trap to measure the neutron distribution as a function of height and measure the influence of marginally trapped UCN on the neutron lifetime measurement. Additionally, measurements have demonstrated phase-space evolution and its effect on the lifetime measurement.

The Effect of Stress and TiC Coated Balls on Lubricant Lifetimes Using a Vacuum Ball-on-Plate Rolling Contact Tribometer

NASA Technical Reports Server (NTRS)

Jones, William R., Jr.; Jansen, Mark J.; Helmick, Larry H.; Nguyen, QuynhGiao; Wheeler, Donald R.; Voving, Hans J.

1999-01-01

A vacuum ball-on-plate rolling contact tribometer was used to determine the relative lifetimes of a perfluoropolyether (Krytox 143 AC) on 440C stainless steel. The effect of mean Hertzian stresses (0.75, 1.0, 1.5 and 2.0 GPa) and the use of TiC coated balls on lubricant lifetime was studied. Other conditions included: approximately 100 rpm, approximately 50 micrograms of lubricant, an initial vacuum level of less than 1.0 x 1O(exp -8) Torr, and room temperature (approximately 23 C). increasing the mean Hertzian stress from 0.75 to 2.0 GPa results in an exponential decrease in lubricant lifetime for both material combinations. However. substituting a TiC ball for the 440C ball quadrupled lifetime at low stress levels (0.75 and 1.0 GPa) and doubled life at higher stresses (1.5 and 2.0 GPa). The reduced reactivity of the TiC surface with the PFPE lubricant is considered to be the reason for this enhancement. Decreasing lifetime with increasing stress levels correlated well with energy dissipation calculations.

The Effect of Stress and TiC Coated Balls on Lifetime of a Perfluoropolyalkylether Using a Vacuum Rolling Contact Tribometer

NASA Technical Reports Server (NTRS)

Jones, William R., Jr.; Pepper, Stephen; Jansen, Mark J.; Nguyen, QuynhGiao; Wheeler, Donald R.; Schroeer, Achim

2000-01-01

A vacuum spiral orbit tribometer (SOT) was used to determine the relative lifetimes of a branched perfluoropolyalkylether (PFPAE) on 440 C stainless steel. The effect of varying the mean Hertzian stress (0.75, 1.0, 1.5 and 2.0 GPa) and the use of TiC coated balls on lubricant lifetime was studied. Other conditions included: approx. 100 rpm, approx. 50 micro-g of lubricant, an initial vacuum level of less than 1.3 x 10(exp -6) Pa (less than 10 x 10(exp -8) Torr), and room temperature (approx. 23 C). Increasing the mean Hertzian stress from 0.75 to 2.0 GPa results in an exponential decrease in lubricant lifetime for both material combinations. However, substituting a TiC ball for the 440 C ball quadrupled lifetime at low stress levels (0.75 and 1.0 GPa) and doubled life at higher stresses (1.5 and 2.0 GPa), The reduced reactivity of the TiC surface with the PFPAE lubricant is considered to be the reason for this enhancement. Decreasing lifetime with increasing stress levels correlated well with energy dissipation calculations.

Determination of several families of phytochemicals in different pre-cooked convenience vegetables: effect of lifetime and cooking.

PubMed

Alarcón-Flores, M Isabel; Hernández-Sánchez, Francisco; Romero-González, Roberto; Plaza-Bolaños, Patricia; Martínez Vidal, J Luis; Garrido Frenich, Antonia

2014-11-01

Phytochemicals content, including several families such as phenolic acids, isoflavones, flavones, flavonols, isothiocyanates, and glucosinolates, was determined in pre-cooked convenience vegetables by ultra high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS). It was observed that there is not a common behavior of the individual concentration of phytochemicals during the lifetime and cooking of the matrix, and compounds change their concentration without a specific trend. It was observed that neither lifetime nor cooking process have significant effects on the total content of phytochemicals except in broccoli, although some changes in the individual content of the target compounds were observed, suggesting that interconversion processes could be performed during the lifetime and/or cooking process of the product.

Effects of lifetime tobacco, alcohol and drug use on psychological and behavioral problems among 10th grade students in Istanbul.

PubMed

Evren, Cuneyt; Evren, Bilge; Bozkurt, Muge; Ciftci-Demirci, Arzu

2015-11-01

The aim of this study was to determine the effects of life-time tobacco, alcohol, and substance use on psychological and behavioral variables among 10th grade students in Istanbul/Turkey. This study employed a cross-sectional online self-report survey conducted in 45 schools from the 15 districts in Istanbul. The questionnaire featured a section about use of substances, including tobacco, alcohol, and drugs. The depression, anxiety, anger, assertiveness, sensation seeking and impulsiveness subscales of the Psychological Screening Test for Adolescents (PSTA) were used. The analyses were conducted based on 4957 subjects. Logistic regression analyses were conducted with each school with the related and behavioral variables as the dependent variables. Gender, tobacco, alcohol, and drug use being the independent variables. All four independent variables predicted the dependent variables. Lifetime tobacco and drug use had significant effects on all the subscale score, whereas lifetime alcohol use had significant effects on all the subscale scores other than lack of assertiveness, and male gender was a significant covariant for all the subscale scores. Drug use showed the highest effect on dependent variables. Interaction was found between effects of tobacco and alcohol on anxiety, whereas interactions were found between effects of tobacco and drugs on lack of assertiveness and impulsiveness. The findings suggested that male students with lifetime tobacco, alcohol or drug use have particularly high risk of psychological and behavioral problems. The unique effects of substance clusters on these problems may be useful in developing secondary preventive practices for substance use and abuse problems in Istanbul.

Pixelation Effects in Weak Lensing

NASA Technical Reports Server (NTRS)

High, F. William; Rhodes, Jason; Massey, Richard; Ellis, Richard

2007-01-01

Weak gravitational lensing can be used to investigate both dark matter and dark energy but requires accurate measurements of the shapes of faint, distant galaxies. Such measurements are hindered by the finite resolution and pixel scale of digital cameras. We investigate the optimum choice of pixel scale for a space-based mission, using the engineering model and survey strategy of the proposed Supernova Acceleration Probe as a baseline. We do this by simulating realistic astronomical images containing a known input shear signal and then attempting to recover the signal using the Rhodes, Refregier, and Groth algorithm. We find that the quality of shear measurement is always improved by smaller pixels. However, in practice, telescopes are usually limited to a finite number of pixels and operational life span, so the total area of a survey increases with pixel size. We therefore fix the survey lifetime and the number of pixels in the focal plane while varying the pixel scale, thereby effectively varying the survey size. In a pure trade-off for image resolution versus survey area, we find that measurements of the matter power spectrum would have minimum statistical error with a pixel scale of 0.09' for a 0.14' FWHM point-spread function (PSF). The pixel scale could be increased to 0.16' if images dithered by exactly half-pixel offsets were always available. Some of our results do depend on our adopted shape measurement method and should be regarded as an upper limit: future pipelines may require smaller pixels to overcome systematic floors not yet accessible, and, in certain circumstances, measuring the shape of the PSF might be more difficult than those of galaxies. However, the relative trends in our analysis are robust, especially those of the surface density of resolved galaxies. Our approach thus provides a snapshot of potential in available technology, and a practical counterpart to analytic studies of pixelation, which necessarily assume an idealized shape measurement method.

Cement hydration from hours to centuries controlled by diffusion through barrier shells of C-S-H

NASA Astrophysics Data System (ADS)

Rahimi-Aghdam, Saeed; Bažant, Zdeněk P.; Abdolhosseini Qomi, M. J.

2017-02-01

Although a few good models for cement hydration exist, they have some limitations. Some do not take into account the complete range of variation of pore relative humidity and temperature, and apply over durations limited from up a few months to up to about a year. The ones that are applicable for long durations are either computationally too intensive for use in finite element programs or predict the hydration to terminate after few months. However, recent tests of autogenous shrinkage and swelling in water imply that the hydration may continue, at decaying rate, for decades, provided that a not too low relative pore humidity (above 0.7) persists for a long time, as expected for the cores of thick concrete structural members. Therefore, and because design lifetimes of over hundred years are required for large concrete structures, a new hydration model for a hundred year lifespan and beyond is developed. The new model considers that, after the first day of hydration, the remnants of anhydrous cement grains, gradually consumed by hydration, are enveloped by contiguous, gradually thickening, spherical barrier shells of calcium-silicate hydrate (C-S-H). The hydration progress is controlled by transport of water from capillary pores through the barrier shells toward the interface with anhydrous cement. The transport is driven by a difference of humidity, defined by equivalence with the difference in chemical potential of water. Although, during the period of 4-24 h, the C-S-H forms discontinuous nano-globules around the cement grain, an equivalent barrier shell control was formulated for this period, too, for ease and effectiveness of calculation. The entire model is calibrated and validated by published test data on the evolution of hydration degree for various cement types, particle size distributions, water-cement ratios and temperatures. Computationally, this model is sufficiently effective for calculating the evolution of hydration degree (or aging) at every integration point of every finite element in a large structure.

Setting Performance Standards for a Cost-Effective Human Immunodeficiency Virus Cure Strategy in South Africa

PubMed Central

Paltiel, A. David; Zheng, Amy; Weinstein, Milton C.; Gaynes, Melanie R.; Wood, Robin; Freedberg, Kenneth A.; Sax, Paul E.

2017-01-01

Abstract Background. Reports of a single case of human immunodeficiency virus (HIV) eradication suggest that elimination of HIV from individuals is possible. Anticipating both increased research funding and the development of effective, durable cure technologies, we describe the circumstances under which a cure might improve survival and be cost-effective in South Africa. Methods. We adapted a simulation model comparing a hypothetical cure strategy (“Cure”) to the standard of care, lifetime antiretroviral therapy (“LifetimeART”) among adherent South Africans (58% female; mean age 33.8 years; mean CD4 257/µL; virologic suppression ≥1 year). We portrayed cure as a single intervention, producing sustained viral eradication without ART. We considered both a plausible, more imminently achievable “Baseline Scenario” and a more aspirational “Optimistic Scenario”. Inputs (Baseline/Optimistic) included the following: 50%/75% efficacy; 0.6%/0.0% fatal toxicity; 0.37%/0.085% monthly relapse over 5 years (0.185%/0.0425% per month thereafter); and $2000/$500 cost. These inputs were varied extensively in sensitivity analysis. Results. At baseline, Cure was “dominated,” yielding lower discounted life expectancy (19.31 life-years [LY] vs 19.37 LY) and greater discounted lifetime costs ($13 800 vs $13 700) than LifetimeART. Under optimistic assumptions, Cure was “cost-saving,” producing greater survival (19.91 LY) and lower lifetime costs ($11 000) than LifetimeART. Findings were highly sensitive to data assumptions, leaving little middle ground where a tradeoff existed between improved survival and higher costs. Conclusions. Only under the most favorable performance assumptions will an HIV cure strategy prove clinically and economically justifiable in South Africa. The scientific pursuit of a cure should not undermine continued expansions of access to proven, effective, and cost-effective ART. PMID:28680903

Cost-effectiveness of human papillomavirus vaccination and cervical cancer screening in Thailand.

PubMed

Sharma, M; Ortendahl, J; van der Ham, E; Sy, S; Kim, J J

2012-01-01

To assess the health and economic outcomes of various screening and vaccination strategies for cervical cancer prevention. Cost-effectiveness analysis from a societal perspective. Thailand. Females aged 9 years and older. Using a mathematical model of human papillomavirus (HPV) infection and cervical cancer, calibrated to epidemiological data from Thailand, we estimated the cost-effectiveness of pre-adolescent HPV vaccination, screening [visual inspection with acetic acid (VIA), HPV DNA testing, and cytology] between one and five times per lifetime in adulthood, and combined pre-adolescent vaccination and screening. Vaccine efficacy, coverage, cost, and screening frequency were varied in sensitivity analyses. Incremental cost-effectiveness ratios, expressed as cost per year of life saved (YLS). Assuming lifelong efficacy and 80% coverage, pre-adolescent HPV vaccination alone was projected to reduce the lifetime risk of cervical cancer by 55%, which was greater than any strategy of screening alone. When cost per vaccinated girl was I$10 (approximately $2 per dose) or less, HPV vaccination alone was cost saving. Pre-adolescent vaccination and HPV DNA testing five times per lifetime, starting at age 35 years, reduced the lifetime cervical cancer risk by 70%, and had a cost-effectiveness ratio less than Thailand's GDP per capita (I$8100), provided the cost per vaccinated girl was I$200 or less. Low cost pre-adolescent HPV vaccination followed by HPV screening five times per lifetime is an efficient strategy for Thailand. Costs may need to be lower, however, for this strategy to be affordable. If vaccination is not feasible, HPV DNA testing five times per lifetime is efficient. © 2011 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2011 RCOG.

Weak lasing in one-dimensional polariton superlattices

PubMed Central

Zhang, Long; Xie, Wei; Wang, Jian; Poddubny, Alexander; Lu, Jian; Wang, Yinglei; Gu, Jie; Liu, Wenhui; Xu, Dan; Shen, Xuechu; Rubo, Yuri G.; Altshuler, Boris L.; Kavokin, Alexey V.; Chen, Zhanghai

2015-01-01

Bosons with finite lifetime exhibit condensation and lasing when their influx exceeds the lasing threshold determined by the dissipative losses. In general, different one-particle states decay differently, and the bosons are usually assumed to condense in the state with the longest lifetime. Interaction between the bosons partially neglected by such an assumption can smear the lasing threshold into a threshold domain—a stable lasing many-body state exists within certain intervals of the bosonic influxes. This recently described weak lasing regime is formed by the spontaneously symmetry breaking and phase-locking self-organization of bosonic modes, which results in an essentially many-body state with a stable balance between gains and losses. Here we report, to our knowledge, the first observation of the weak lasing phase in a one-dimensional condensate of exciton–polaritons subject to a periodic potential. Real and reciprocal space photoluminescence images demonstrate that the spatial period of the condensate is twice as large as the period of the underlying periodic potential. These experiments are realized at room temperature in a ZnO microwire deposited on a silicon grating. The period doubling takes place at a critical pumping power, whereas at a lower power polariton emission images have the same periodicity as the grating. PMID:25787253

Near-field fluorescence thermometry using highly efficient triple-tapered near-field optical fiber probe.

PubMed

Fujii, T; Taguchi, Y; Saiki, T; Nagasaka, Y

2012-12-01

A novel local temperature measurement method using fluorescence near-field optics thermal nanoscopy (Fluor-NOTN) has been developed. Fluor-NOTN enables nanoscale temperature measurement in situ by detecting the temperature-dependent fluorescence lifetime of CdSe quantum dots (QDs). In this paper, we report a novel triple-tapered near-field optical fiber probe that can increase the temperature measurement sensitivity of Fluor-NOTN. The performance of the proposed probe was numerically evaluated by the finite difference time domain method. Due to improvements in both the throughput and collection efficiency of near-field light, the sensitivity of the proposed probe was 1.9 times greater than that of typical double-tapered probe. The proposed shape of the triple-tapered core was successfully fabricated utilizing a geometrical model. The detected signal intensity of dried layers of QDs was greater by more than two orders than that of auto-fluorescence from the fiber core. In addition, the near-field fluorescence lifetime of the QDs and its temperature dependence were successfully measured by the fabricated triple-tapered near-field optical fiber probe. These measurement results verified the capability of the proposed triple-tapered near-field optical fiber probe to improve the collection efficiency of near-field fluorescence.

Thermal conductivity of graphene mediated by strain and size

DOE PAGES

Kuang, Youdi; Shi, Sanqiang; Wang, Xinjiang; ...

2016-06-09

Based on first-principles calculations and full iterative solution of the linearized Boltzmann–Peierls transport equation for phonons, we systematically investigate effects of strain, size and temperature on the thermal conductivity k of suspended graphene. The calculated size-dependent and temperature-dependent k for finite samples agree well with experimental data. The results show that, contrast to the convergent room-temperature k = 5450 W/m-K of unstrained graphene at a sample size ~8 cm, k of strained graphene diverges with increasing the sample size even at high temperature. Out-of-plane acoustic phonons are responsible for the significant size effect in unstrained and strained graphene due tomore » their ultralong mean free path and acoustic phonons with wavelength smaller than 10 nm contribute 80% to the intrinsic room temperature k of unstrained graphene. Tensile strain hardens the flexural modes and increases their lifetimes, causing interesting dependence of k on sample size and strain due to the competition between boundary scattering and intrinsic phonon–phonon scattering. k of graphene can be tuned within a large range by strain for the size larger than 500 μm. These findings shed light on the nature of thermal transport in two-dimensional materials and may guide predicting and engineering k of graphene by varying strain and size.« less

Life prediction of thermally highly loaded components: modelling the damage process of a rocket combustion chamber hot wall

NASA Astrophysics Data System (ADS)

Schwarz, W.; Schwub, S.; Quering, K.; Wiedmann, D.; Höppel, H. W.; Göken, M.

2011-09-01

During their operational life-time, actively cooled liners of cryogenic combustion chambers are known to exhibit a characteristic so-called doghouse deformation, pursued by formation of axial cracks. The present work aims at developing a model that quantitatively accounts for this failure mechanism. High-temperature material behaviour is characterised in a test programme and it is shown that stress relaxation, strain rate dependence, isotropic and kinematic hardening as well as material ageing have to be taken into account in the model formulation. From fracture surface analyses of a thrust chamber it is concluded that the failure mode of the hot wall ligament at the tip of the doghouse is related to ductile rupture. A material model is proposed that captures all stated effects. Basing on the concept of continuum damage mechanics, the model is further extended to incorporate softening effects due to material degradation. The model is assessed on experimental data and quantitative agreement is established for all tests available. A 3D finite element thermo-mechanical analysis is performed on a representative thrust chamber applying the developed material-damage model. The simulation successfully captures the observed accrued thinning of the hot wall and quantitatively reproduces the doghouse deformation.

Dissipative entanglement swapping in the presence of detuning and Kerr medium: Bell state measurement method

NASA Astrophysics Data System (ADS)

Ghasemi, M.; Tavassoly, M. K.; Nourmandipour, A.

2017-12-01

In this paper, we investigate the possibility of entanglement swapping between two independent nonperfect cavities consisting of an atom with finite lifetime of atomic levels (as two independent sources of dissipation), which interacts with a quantized electromagnetic field in the presence of detuning and Kerr medium. In fact, there is no direct interaction between the two atoms, therefore, no entanglement exists between them. We use the Bell state measurement performed on the photons leaving the cavities to swap the entanglement stored between the atom-fields in each cavity into atom-atom. Our motivation comes from the fact that two-qubit entangled states are of great interest for quantum information science and technologies. We discuss the effect of the initial state of the system, the detuning parameter, the Kerr medium and the two dissipation sources on the swapped entanglement to atom-atom. We interestingly find that when the atomic decay rates and photonic leakages from the cavities are equal, our system behaves as an ideal system with no dissipation. Our results show that it is possible to create a long-living atom-atom maximally entangled state in the presence of Kerr effect and dissipation; we determine these conditions in detail and also establish the final atom-atom Bell state.

Matrix elements of Δ B =0 operators in heavy hadron chiral perturbation theory

NASA Astrophysics Data System (ADS)

Lee, Jong-Wan

2015-05-01

We study the light-quark mass and spatial volume dependence of the matrix elements of Δ B =0 four-quark operators relevant for the determination of Vu b and the lifetime ratios of single-b hadrons. To this end, one-loop diagrams are computed in the framework of heavy hadron chiral perturbation theory with partially quenched formalism for three light-quark flavors in the isospin limit; flavor-connected and -disconnected diagrams are carefully analyzed. These calculations include the leading light-quark flavor and heavy-quark spin symmetry breaking effects in the heavy hadron spectrum. Our results can be used in the chiral extrapolation of lattice calculations of the matrix elements to the physical light-quark masses and to infinite volume. To provide insight on such chiral extrapolation, we evaluate the one-loop contributions to the matrix elements containing external Bd, Bs mesons and Λb baryon in the QCD limit, where sea and valence quark masses become equal. In particular, we find that the matrix elements of the λ3 flavor-octet operators with an external Bd meson receive the contributions solely from connected diagrams in which current lattice techniques are capable of precise determination of the matrix elements. Finite volume effects are at most a few percent for typical lattice sizes and pion masses.

What is the lifetime risk of developing cancer?: the effect of adjusting for multiple primaries

PubMed Central

Sasieni, P D; Shelton, J; Ormiston-Smith, N; Thomson, C S; Silcocks, P B

2011-01-01

Background: The ‘lifetime risk' of cancer is generally estimated by combining current incidence rates with current all-cause mortality (‘current probability' method) rather than by describing the experience of a birth cohort. As individuals may get more than one type of cancer, what is generally estimated is the average (mean) number of cancers over a lifetime. This is not the same as the probability of getting cancer. Methods: We describe a method for estimating lifetime risk that corrects for the inclusion of multiple primary cancers in the incidence rates routinely published by cancer registries. The new method applies cancer incidence rates to the estimated probability of being alive without a previous cancer. The new method is illustrated using data from the Scottish Cancer Registry and is compared with ‘gold-standard' estimates that use (unpublished) data on first primaries. Results: The effect of this correction is to make the estimated ‘lifetime risk' smaller. The new estimates are extremely similar to those obtained using incidence based on first primaries. The usual ‘current probability' method considerably overestimates the lifetime risk of all cancers combined, although the correction for any single cancer site is minimal. Conclusion: Estimation of the lifetime risk of cancer should either be based on first primaries or should use the new method. PMID:21772332

Ayurvedic genomics, constitutional psychology, and endocrinology: the missing connection.

PubMed

Rizzo-Sierra, Carlos V

2011-05-01

A recent methodological approach for human classification, diagnosis, and therapeutics through the combination of current Western constitutional psychology somatotypes and traditional Indian medicine (prakriti) body types and mind (manas) is herein presented. The striking similarities between psychologic somatotypes and Indian medicine body types permits proposal of a finite genopsycho-somatotyping of humans. Genopsycho-somatotyping of humans consists of a set of common physiologic, physical, and psychologic attributes related to a common basic birth constitution that remains somewhat permanent during human lifetime, since it is proposed that this birth constitution is programmed in the person's DNA (genes). This mainly provides a tool for classifying the human population based on broad and finite phenotype clusters across different ethnicity, languages, geographical location, or self-reported ancestry. In spite of any social or environmental traumatic event, I propose for males that every basic constitution has an associated identification organ, a measured property or marker, a soma, and some psyche general tendencies suggesting specific behavior or recurrent conduct. Three (3) basic extreme genopsycho-somatotypes or birth constitutions are enunciated: mesomorphic or andrus (Pitta), endomorphic or thymus (Khapa), and ectomorphic or thyrus (Vata). The method further predicts that male andrus constitution across races shares similarities in androgen (An) nuclear receptor behavior, whereas thymus constitutions are mainly regulated by T-cells (Tc) nuclear receptor behavior. Moreover, it suggests that thyrus constitutions share similarities in thyroxine (Th) nuclear receptor behavior. These proposed nuclear receptors are expected to regulate the expression of specific genes, thereby controlling the embryonic development, adult homeostasis, and metabolism of the human organism in a very profound way. The method finally predicts small differences in measured property (An, Tc, and Th nuclear receptors behavior) within a birth constitution across different races to be expected by modulation effects in melanocyte-stimulating hormone receptor behavior.

Fluorescence lifetime plate reader: Resolution and precision meet high-throughput

PubMed Central

Petersen, Karl J.; Peterson, Kurt C.; Muretta, Joseph M.; Higgins, Sutton E.; Gillispie, Gregory D.; Thomas, David D.

2014-01-01

We describe a nanosecond time-resolved fluorescence spectrometer that acquires fluorescence decay waveforms from each well of a 384-well microplate in 3 min with signal-to-noise exceeding 400 using direct waveform recording. The instrument combines high-energy pulsed laser sources (5–10 kHz repetition rate) with a photomultiplier and high-speed digitizer (1 GHz) to record a fluorescence decay waveform after each pulse. Waveforms acquired from rhodamine or 5-((2-aminoethyl)amino) naphthalene-1-sulfonic acid dyes in a 384-well plate gave lifetime measurements 5- to 25-fold more precise than the simultaneous intensity measurements. Lifetimes as short as 0.04 ns were acquired by interleaving with an effective sample rate of 5 GHz. Lifetime measurements resolved mixtures of single-exponential dyes with better than 1% accuracy. The fluorescence lifetime plate reader enables multiple-well fluorescence lifetime measurements with an acquisition time of 0.5 s per well, suitable for high-throughput fluorescence lifetime screening applications. PMID:25430092

Lateral microheterogeneity of diphenylhexatriene-labeled choline phospholipids in the erythrocyte ghost membrane as determined by time-resolved fluorescence spectroscopy.

PubMed

Prenner, E; Sommer, A; Maurer, N; Glatter, O; Gorges, R; Paltauf, F; Hermetter, A

2000-04-01

Choline phospholipids are the major constituents of the outer layer of the erythrocyte membrane. To investigate their lateral membrane organization we determined the fluorescence lifetime properties of diphenylhexatriene analogues of phosphatidylcholine, choline plasmalogen, (the respective enolether derivative), and sphingomyelin inserted into the outer layer of hemoglobin-free ghosts. Fluorescence lifetimes were recorded by time-resolved phase and modulation fluorometry and analyzed in terms of Continuous Lorentzian distributions. To assess the influence of membrane proteins on the fluorescence lifetime of the labeled lipids in the biomembrane, lipid vesicles were used as controls. In general, the lifetime distributions in the ghost membranes are broad compared to vesicles. Phosphatidylcholine and sphingomyelin exhibit very similar lifetime distributions in contrast to an increased plasmalogen lifetime heterogeneity in both systems. Orientational effects of side chain mobilities on the observed lifetimes can be excluded. Fluorescence anisotropies revealed identical values for all three labeled phospholipids in the biomembrane.

Some effects of finite spatial resolution on skin friction measurements in turbulent boundary layers

NASA Technical Reports Server (NTRS)

Westphal, Russell V.

1988-01-01

The effects of finite spatial resolution often cause serious errors in measurements in turbulent boundary layers, with particularly large effects for measurements of fluctuating skin friction and velocities within the sublayer. However, classical analyses of finite spatial resolution effects have generally not accounted for the substantial inhomogeneity and anisotropy of near-wall turbulence. The present study has made use of results from recent computational simulations of wall-bounded turbulent flows to examine spatial resolution effects for measurements made at a wall using both single-sensor probes and those employing two sensing volumes in a V shape. Results are presented to show the effects of finite spatial resolution on a variety of quantitites deduced from the skin friction field.

Association between childhood maltreatment and non-medical prescription opioid use among Chinese senior high school students: The moderating role of gender.

PubMed

Lei, Yiling; Xi, Chuhao; Li, Pengsheng; Luo, Min; Wang, Wanxin; Pan, Siyuan; Gao, Xue; Xu, Yan; Huang, Guoliang; Deng, Xueqing; Guo, Lan; Lu, Ciyong

2018-08-01

Non-medical prescription opioid use (NMPOU) and childhood maltreatment are currently serious problems among adolescents worldwide, and childhood maltreatment may be associated with the increased rates of NMPOU. This study examined the specific associations between particular types of childhood maltreatment and lifetime NMPOU and assessed whether gender has a moderating effect on these associations. A 3-stage, stratified cluster, randomized sampling method was used to collect data from 11,194 high school students in Chongqing. The prevalence of the lifetime NMPOU among senior high school students in Chongqing was 7.7%. Physical abuse (AOR = 1.11, 95% CI = 1.07-1.14), emotional abuse (AOR = 1.05, 95% CI = 1.03-1.08), sexual abuse (AOR = 1.04, 95% CI = 1.01-1.07), physical neglect (AOR = 1.06, 95% CI = 1.04-1.09), and emotional neglect (AOR = 1.03, 95% CI = 1.02-1.04) were all positively associated with lifetime NMPOU. The moderating effects of gender on emotional abuse (P = 0.004) and sexual abuse (P = 0.019) were statistically significant in the adjusted model of lifetime NMPOU. According to the stratification analyses in which the male and female students were analyzed separately, female students who previously experienced emotional/sexual abuse had a higher prevalence of lifetime NMPOU. The study sample only contained school students and cross-sectional design limited our ability to make causal inferences. Childhood maltreatment was positively associated with lifetime NMPOU, and gender had a moderating effect on the associations between childhood maltreatment and lifetime NMPOU. Early identification of and intervention for childhood maltreatment victims, particularly female victims, may help reduce the lifetime risk of NMPOU. Copyright © 2018 Elsevier B.V. All rights reserved.

High-purity silicon crystal growth investigations

NASA Technical Reports Server (NTRS)

Ciszek, T. F.; Hurd, J. L.; Schuyler, T.

1985-01-01

The study of silicon sheet material requirements for high efficiency solar cells is reported. Research continued on obtaining long lifetime single crystal float zone silicon and on understanding and reducing the mechanisms that limit the achievement of long lifetimes. The mechanisms studied are impurities, thermal history, point defects, and surface effect. The lifetime related crystallographic defects are characterized by X-ray topography and electron beam induced current.

Addressing the Health Concerns of VA Women With Sexual Trauma

DTIC Science & Technology

2016-10-01

SUPPLEMENTARY NOTES 14. ABSTRACT Lifetime ST disproportionately affects women veterans and can threaten their health and wellbeing. PTSD, IPV, and...alcohol use are closely interrelated and significant concerns for women veterans with lifetime ST . Providing effective and low-cost interventions to...address ST -related risks among women veterans with lifetime ST would advance clinical care for these women in an important area. 15. SUBJECT TERMS

Health and economic impact of HPV 16 and 18 vaccination and cervical cancer screening in India

PubMed Central

Diaz, M; Kim, J J; Albero, G; de Sanjosé, S; Clifford, G; Bosch, F X; Goldie, S J

2008-01-01

Cervical cancer is a leading cause of cancer death among women in low-income countries, with ∼25% of cases worldwide occurring in India. We estimated the potential health and economic impact of different cervical cancer prevention strategies. After empirically calibrating a cervical cancer model to country-specific epidemiologic data, we projected cancer incidence, life expectancy, and lifetime costs (I$2005), and calculated incremental cost-effectiveness ratios (I$/YLS) for the following strategies: pre-adolescent vaccination of girls before age 12, screening of women over age 30, and combined vaccination and screening. Screening differed by test (cytology, visual inspection, HPV DNA testing), number of clinical visits (1, 2 or 3), frequency (1 × , 2 × , 3 × per lifetime), and age range (35–45). Vaccine efficacy, coverage, and costs were varied in sensitivity analyses. Assuming 70% coverage, mean reduction in lifetime cancer risk was 44% (range, 28–57%) with HPV 16,18 vaccination alone, and 21–33% with screening three times per lifetime. Combining vaccination and screening three times per lifetime provided a mean reduction of 56% (vaccination plus 3-visit conventional cytology) to 63% (vaccination plus 2-visit HPV DNA testing). At a cost per vaccinated girl of I$10 (per dose cost of $2), pre-adolescent vaccination followed by screening three times per lifetime using either VIA or HPV DNA testing, would be considered cost-effective using the country's per capita gross domestic product (I$3452) as a threshold. In India, if high coverage of pre-adolescent girls with a low-cost HPV vaccine that provides long-term protection is achievable, vaccination followed by screening three times per lifetime is expected to reduce cancer deaths by half, and be cost-effective. PMID:18612311

Effects of lifetime stress exposure on mental and physical health in young adulthood: How stress degrades and forgiveness protects health.

PubMed

Toussaint, Loren; Shields, Grant S; Dorn, Gabriel; Slavich, George M

2016-06-01

To examine risk and resilience factors that affect health, lifetime stress exposure histories, dispositional forgiveness levels, and mental and physical health were assessed in 148 young adults. Greater lifetime stress severity and lower levels of forgiveness each uniquely predicted worse mental and physical health. Analyses also revealed a graded Stress × Forgiveness interaction effect, wherein associations between stress and mental health were weaker for persons exhibiting more forgiveness. These data are the first to elucidate the interactive effects of cumulative stress severity and forgiveness on health, and suggest that developing a more forgiving coping style may help minimize stress-related disorders. © The Author(s) 2014.

Moisture dependence of positron lifetime in Kevlar-49

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Holt, William H.; Mock, Willis, Jr.

1984-01-01

Because of filamentary character of Kevlar-49 aramid fibers, there is some concern about the moisture uptake and its effect on plastic composites reinforced with Kevlar-49 fibers. As part of continuing studies of positron lifetime in polymers, we have measured positron lifetime spectra in Kevlar-49 fibers as a function of their moisture content. The long lifetime component intensities are rather low, being only of the order of 2-3 percent. The measured values of long component lifetimes at various moisture levels in the specimens are as follows: 2072 +/- 173 ps (dry); 2013 +/- 193 ps (20.7 percent saturation); 1665 +/- 85 ps (25.7 percent saturation); 1745 +/- 257 ps (32.1 percent saturation); and 1772 +/- 217 ps (100 percent saturation). It is apparent that the long component lifetime at first decreases and then increases as the specimen moisture content increases. These results have been compared with those inferred from Epon-815 and Epon-815/K-49 composite data.

Origin of long lifetime of band-edge charge carriers in organic–inorganic lead iodide perovskites

PubMed Central

Chen, Tianran; Chen, Wei-Liang; Foley, Benjamin J.; Lee, Jooseop; Ruff, Jacob P. C.; Ko, J. Y. Peter; Brown, Craig M.; Harriger, Leland W.; Zhang, Depei; Park, Changwon; Yoon, Mina; Chang, Yu-Ming; Choi, Joshua J.; Lee, Seung-Hun

2017-01-01

Long carrier lifetime is what makes hybrid organic–inorganic perovskites high-performance photovoltaic materials. Several microscopic mechanisms behind the unusually long carrier lifetime have been proposed, such as formation of large polarons, Rashba effect, ferroelectric domains, and photon recycling. Here, we show that the screening of band-edge charge carriers by rotation of organic cation molecules can be a major contribution to the prolonged carrier lifetime. Our results reveal that the band-edge carrier lifetime increases when the system enters from a phase with lower rotational entropy to another phase with higher entropy. These results imply that the recombination of the photoexcited electrons and holes is suppressed by the screening, leading to the formation of polarons and thereby extending the lifetime. Thus, searching for organic–inorganic perovskites with high rotational entropy over a wide range of temperature may be a key to achieve superior solar cell performance. PMID:28673975

Origin of long lifetime of band-edge charge carriers in organic-inorganic lead iodide perovskites.

PubMed

Chen, Tianran; Chen, Wei-Liang; Foley, Benjamin J; Lee, Jooseop; Ruff, Jacob P C; Ko, J Y Peter; Brown, Craig M; Harriger, Leland W; Zhang, Depei; Park, Changwon; Yoon, Mina; Chang, Yu-Ming; Choi, Joshua J; Lee, Seung-Hun

2017-07-18

Long carrier lifetime is what makes hybrid organic-inorganic perovskites high-performance photovoltaic materials. Several microscopic mechanisms behind the unusually long carrier lifetime have been proposed, such as formation of large polarons, Rashba effect, ferroelectric domains, and photon recycling. Here, we show that the screening of band-edge charge carriers by rotation of organic cation molecules can be a major contribution to the prolonged carrier lifetime. Our results reveal that the band-edge carrier lifetime increases when the system enters from a phase with lower rotational entropy to another phase with higher entropy. These results imply that the recombination of the photoexcited electrons and holes is suppressed by the screening, leading to the formation of polarons and thereby extending the lifetime. Thus, searching for organic-inorganic perovskites with high rotational entropy over a wide range of temperature may be a key to achieve superior solar cell performance.

Finite-size effects on the radiative energy loss of a fast parton in hot and dense strongly interacting matter

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

Caron-Huot, Simon; Gale, Charles

2010-12-15

We consider finite-size effects on the radiative energy loss of a fast parton moving in a finite-temperature, strongly interacting medium, using the light-cone path integral formalism put forward by B. G. Zakharov [JETP Lett. 63, 952 (1996); 65, 615 (1997)]. We present a convenient reformulation of the problem that makes possible its exact numerical analysis. This is done by introducing the concept of a radiation rate in the presence of finite-size effects. This effectively extends the finite-temperature approach of Arnold, Moore, and Yaffe [J. High Energy Phys. 11 (2001) 057; 12 (2001) 009; 06 (2001) 030] (AMY) to include interferencemore » between vacuum and medium radiation. We compare results with those obtained in the regime considered by AMY, with those obtained at leading order in an opacity expansion, and with those obtained deep in the Landau-Pomeranchuk-Migdal regime.« less

Lifetime-vibrational interference effects in resonantly excited x-ray emission spectra of CO

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

Skytt, P.; Glans, P.; Gunnelin, K.

1997-04-01

The parity selection rule for resonant X-ray emission as demonstrated for O{sub 2} and N{sub 2} can be seen as an effect of interference between coherently excited degenerate localized core states. One system where the core state degeneracy is not exact but somewhat lifted was previously studied at ALS, namely the resonant X-ray emission of amino-substituted benzene (aniline). It was shown that the X-ray fluorescence spectrum resulting from excitation of the C1s at the site of the {open_quotes}aminocarbon{close_quotes} could be described in a picture separating the excitation and the emission processes, whereas the spectrum corresponding to the quasi-degenerate carbons couldmore » not. Thus, in this case it was necessary to take interference effects between the quasi-degenerate intermediate core excited states into account in order to obtain agreement between calculations and experiment. The different vibrational levels of core excited states in molecules have energy splittings which are of the same order of magnitude as the natural lifetime broadening of core excitations in the soft X-ray range. Therefore, lifetime-vibrational interference effects are likely to appear and influence the band shapes in resonant X-ray emission spectra. Lifetime-vibrational interference has been studied in non-resonant X-ray emission, and in Auger spectra. In this report the authors discuss results of selectively excited soft X-ray fluorescence spectra of molecules, where they focus on lifetime-interference effects appearing in the band shapes.« less

Frontiers, Opportunities and Challenges for a Hydrogen Economy

NASA Astrophysics Data System (ADS)

Turner, John

2015-03-01

Energy carriers are the staple for powering the society we live in. Coal, oil, natural gas, gasoline and diesel all carry energy in chemical bonds, used in almost all areas of our civilization. But these carriers have a limited-use lifetime on this planet. They are finite, contribute to climate change and carry significant geopolitical issues. If mankind is to maintain and grow our societies, new energy carriers must be developed and deployed into our energy infrastructure. Hydrogen is the simplest of all the energy carriers and when refined from water using renewable energies like solar and wind, represents a sustainable energy carrier, viable for millennia to come. This talk with discuss the challenges for sustainable production of hydrogen, along with the promise and possible pathways for implementing hydrogen into our energy infrastructure.

Structure-induced asymmetry between counterpropagating modes and the reciprocity principle in whistle-geometry ring lasers

NASA Astrophysics Data System (ADS)

Osiński, Marek; Kalagara, Hemashilpa; Lee, Hosuk; Smolyakov, Gennady A.

2017-08-01

Greatly enhanced high-speed modulation performance has been recently predicted in numerical calculations for a novel injection-locking scheme involving a distributed Bragg reflector master laser monolithically integrated with a unidirectional whistle-geometry semiconductor microring laser. Operation of these devices relies on the assumption of large difference between modal losses experienced by counterpropagating modes. In this work, we confirm the unidirectionality of the whistle-geometry configuration through rigorous three-dimensional finite-difference timedomain (FDTD) simulation by showing a strong asymmetry in photon lifetimes between the two counterpropagating modes. We also show that similar asymmetry occurs in three-port couplers, whose structure resembles the coupling section of whistle-geometry lasers. We explain why these results do not violate the Helmholtz reciprocity principle.

Spatiotemporal perspective on the decay of turbulence in wall-bounded flows.

PubMed

Manneville, Paul

2009-02-01

By use of a reduced model focusing on the in-plane dependence of plane Couette flow, it is shown that the turbulent-->laminar relaxation process can be understood as a nucleation problem similar to that occurring at a thermodynamic first-order phase transition. The approach, apt to deal with the large extension of the system considered, challenges the current interpretation in terms of chaotic transients typical of temporal chaos. The study of the distribution of the sizes of laminar domains embedded in turbulent flow proves that an abrupt transition from sustained spatiotemporal chaos to laminar flow can take place at some given value of the Reynolds number Rlow, whether or not the local chaos lifetime, as envisioned within low-dimensional dynamical systems theory, diverges at finite R beyond Rlow.

Constraints on braneworld gravity models from a kinematic limit on the age of the black hole XTE J1118+480.

PubMed

Psaltis, Dimitrios

2007-05-04

In braneworld gravity models with a finite anti-de Sitter space (AdS) curvature in the extra dimension, the AdS/conformal field theory correspondence leads to a prediction for the lifetime of astrophysical black holes that is significantly smaller than the Hubble time, for asymptotic curvatures that are consistent with current experiments. Using the recent measurements of the position, three-dimensional spatial velocity, and mass of the black hole XTE J1118+480, I calculate a lower limit on its kinematic age of > or =11 Myr (95% confidence). This translates into an upper limit for the asymptotic AdS curvature in the extra dimensions of <0.08 mm, which significantly improves the limit obtained by table top experiments of sub mm gravity.

Ultrafast strong broadband light source generated in nanoscale plasmonic Au-AAO-Al structures

NASA Astrophysics Data System (ADS)

Han, Junbo; Yao, Linhua; Ma, Zongwei

we demonstrate an ultrafast strong broadband photoluminescence (PL) from Au-AAO-Al composite under low excitation power intensity of 3.8 34.5 GW /cm2. The emission wavelength is in the range of 450-1050 nm and the lifetime is under sub-nanosecond. Comparative studies of PL in Au-AAO-Al with different Au rod length and Au-AAO without Al coupling layer, together with the finite difference time domain (FDTD) calculations, present that the fast PL originates from the surface plasmon enhanced supercontinuum generation (SCG) in AAO membrane. The observations indicate that strong SCG could be realized in nanoscale plasmonic structures, which have promise applications in the minimization and integration of ultrafast lighting sources in photonic devices. National Natural Scientific Foundation of China (11404124).

Race/ethnicity, socioeconomic status, and lifetime morbidity burden in the women's health initiative: a cross-sectional analysis.

PubMed

Gold, Rachel; Michael, Yvonne L; Whitlock, Evelyn P; Hubbell, F Allan; Mason, Ellen D; Rodriguez, Beatriz L; Safford, Monika M; Sarto, Gloria E

2006-12-01

We sought to assess the extent to which race/ethnicity and socioeconomic status (SES) are independently and jointly related to lifetime morbidity burden by comparing the impact of SES on lifetime morbidity among women of different racial/ethnic groups: white, black, Hispanic, American Indian/Alaska Native (AIAN), and Asian/Pacific Islander (API). Using baseline data from the Women's Health Initiative (WHI), a national study of 162,000 postmenopausal women, we measured lifetime morbidity burden using a modified version of the Charlson Index, and measured SES with educational attainment and household income. In multivariable simple polytomous logistic regression models, we first assessed the effect of SES on lifetime morbidity burden among women of each racial/ethnic group, then assessed the combined effect of race/ethnicity and SES. Five percent of all women in the study population had high lifetime morbidity burden. Women with high lifetime morbidity were more likely to be AIAN or black; poor; less educated; divorced, separated, or widowed; past or current smokers; obese; uninsured or publicly insured. Lower SES was associated with higher morbidity among most women. The extent to which morbidity was higher among lower SES compared to higher SES women was about the same among Hispanic women and white women, but was substantially greater among black and AIAN women compared with white women. This study demonstrates the importance of considering race/ethnicity and class together in relation to health outcomes.

Perimeter Governed Minority Carrier Lifetimes in 4H-SiC p+n Diodes Measured by Reverse Recovery Switching Transient Analysis

NASA Technical Reports Server (NTRS)

Neudeck, Philip G.

1998-01-01

Minority carrier lifetimes in epitaxial 4H-SiC p-n junction diodes were measured via an analysis of reverse recovery switching characteristics. Behavior of reverse recovery storage time (t(sub s)) as a function of initial ON-state forward current (I(sub f)) and OFF-state reverse current (I(sub R)) followed well-documented trends which have been observed for decades in silicon p-n rectifiers. Average minority carrier (hole) lifetimes (tau(sub p)) calculated from plots of t(sub s) vs I(sub R)/I(sub F) strongly decreased with decreasing device area. Bulk and perimeter components of average hole lifetimes were separated by plotting tau(sub p) as a function of device perimeter-to-area ratio (P/A). This plot reveals that perimeter recombination is dominant in these devices, whose areas are all less than 1 square mm. The bulk minority carrier (hole) lifetime extracted from the 1/Tau(sub p) vs P/A plot is approximately 0.7 microns, well above the 60 ns to 300 ns average lifetimes obtained when perimeter recombination effects are ignored in the analysis. Given the fact that there has been little previous investigation of bipolar diode and transistor performance as a function of perimeter-to-area ratio, this work raises the possibility that perimeter recombination may be partly responsible for poor effective minority carrier lifetimes and limited performance obtained in many previous SiC bipolar junction devices.

Measurement and Perturbation of Morphogen Lifetime: Effects on Gradient Shape

PubMed Central

Drocco, Jeffrey A.; Grimm, Oliver; Tank, David W.; Wieschaus, Eric

2011-01-01

Protein lifetime is of critical importance for most biological processes and plays a central role in cell signaling and embryonic development, where it impacts the absolute concentration of signaling molecules and, potentially, the shape of morphogen gradients. Early conceptual and mathematical models of gradient formation proposed that steady-state gradients are established by an equilibration between the lifetime of a morphogen and its rates of synthesis and diffusion, though whether gradients in fact reach steady state before being read out is a matter of controversy. In any case, this class of models predicts that protein lifetime is a key determinant of both the time to steady state and the spatial extent of a gradient. Using a method that employs repeated photoswitching of a fusion of the morphogen Bicoid (Bcd) and the photoconvertible fluorescent protein Dronpa, we measure and modify the lifetime of Dronpa-Bcd in living Drosophila embryos. We find that the lifetime of Bcd is dynamic, changing from 50 min before mitotic cycle 14 to 15 min during cellularization. Moreover, by measuring total quantities of Bcd over time, we find that the gradient does not reach steady state. Finally, using a nearly continuous low-level conversion to the dark state of Dronpa-Bcd to mimic the effect of increased degradation, we demonstrate that perturbation of protein lifetime changes the characteristic length of the gradient, providing direct support for a mechanism based on synthesis, diffusion, and degradation. PMID:22004733

Finite volume effects on the electric polarizability of neutral hadrons in lattice QCD

NASA Astrophysics Data System (ADS)

Lujan, M.; Alexandru, A.; Freeman, W.; Lee, F. X.

2016-10-01

We study the finite volume effects on the electric polarizability for the neutron, neutral pion, and neutral kaon using eight dynamically generated two-flavor nHYP-clover ensembles at two different pion masses: 306(1) and 227(2) MeV. An infinite volume extrapolation is performed for each hadron at both pion masses. For the neutral kaon, finite volume effects are relatively mild. The dependence on the quark mass is also mild, and a reliable chiral extrapolation can be performed along with the infinite volume extrapolation. Our result is αK0 phys=0.356 (74 )(46 )×10-4 fm3 . In contrast, for neutron, the electric polarizability depends strongly on the volume. After removing the finite volume corrections, our neutron polarizability results are in good agreement with chiral perturbation theory. For the connected part of the neutral pion polarizability, the negative trend persists, and it is not due to finite volume effects but likely sea quark charging effects.

High Performance Computing Technologies for Modeling the Dynamics and Dispersion of Ice Chunks in the Arctic Ocean

DTIC Science & Technology

2016-08-23

SECURITY CLASSIFICATION OF: Hybrid finite element / finite volume based CaMEL shallow water flow solvers have been successfully extended to study wave...effects on ice floes in a simplified 10 sq-km ocean domain. Our solver combines the merits of both the finite element and finite volume methods and...ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 sea ice dynamics, shallow water, finite element , finite volume

Effectiveness of the 'Healthy School and Drugs' prevention programme on adolescents' substance use: a randomized clustered trial.

PubMed

Malmberg, Monique; Kleinjan, Marloes; Overbeek, Geertjan; Vermulst, Ad; Monshouwer, Karin; Lammers, Jeroen; Vollebergh, Wilma A M; Engels, Rutger C M E

2014-06-01

To evaluate the effectiveness of the Healthy School and Drugs programme on alcohol, tobacco and marijuana use among Dutch early adolescents. Randomized clustered trial with two intervention conditions (i.e. e-learning and integral). General population of 11-15-year-old adolescents in the Netherlands. A total of 3784 students of 23 Dutch secondary schools. Structured digital questionnaires were administered pre-intervention and at 32 months follow-up. The primary outcome measures were new incidences of alcohol (life-time and 1-month prevalence), tobacco (life-time and 1-month prevalence) and marijuana use (life-time prevalence). Main effect analyses showed no programme effects on incidences of alcohol consumption (life-time prevalence: e-learning condition: B = 0.102, P = 0.549; integral condition: B = -0.157, P = 0.351; 1-month prevalence: e-learning condition: B = 0.191, P = 0.288; integral condition: B = -0.140, P = 0.445), tobacco consumption (life-time prevalence: e-learning condition: B = 0.164, P = 0.444; integral condition: B = 0.160, P = 0.119; 1-month prevalence: e-learning condition: B = 0.088, P = 0.746; integral condition: B = 0.261, P = 0.093), or marijuana consumption (life-time prevalence: e-learning condition: B = 0.070, P = 0.732; integral condition: B = 0.186, P = 0.214). The non-significant impact of the Healthy School and Drugs programme (a Dutch school-based prevention programme for early adolescents) on incidences of alcohol, tobacco and marijuana use indicates that the programme is either ineffective or implemented inadequately. © 2014 Society for the Study of Addiction.

Effect of surface moisture on chemically bonded phosphor for thermographic phosphor thermometry

NASA Astrophysics Data System (ADS)

Cai, Tao; Kim, Dong; Kim, Mirae; Liu, Ying Zheng; Kim, Kyung Chun

2016-09-01

This study examined the effect of surface moisture on the calibration lifetime in chemically bonded phosphor paint preparation. Mg4FGeO6:Mn was used as a sensor material, which was excited by a pulsed UV LED. A high-speed camera with a frequency of 8000 Hz was used to conduct phosphor thermometry. Five samples with different degrees of surface moisture were selected during the preparation process, and each sample was calibrated 40 times at room temperature. A conventional post-processing method was used to acquire the phosphorescent lifetime for different samples with a 4  ×  4-pixel interrogation window. The measurement error and paint uniformity were also studied. The results showed that there was no obvious phosphorescence boundary between the wet parts and dry parts of phosphor paint. The lifetime increased by about 0.0345% per hour during the preparation process, showing the degree of surface moisture had almost no influence on the lifetime measurement. The lifetime changed only after annealing treatment. There was also no effect on the measurement error and uniformity. These results provide a reference for developing a real-time measurement method using thermographic phosphor thermometry. This study also provides a feasible basis for chemically bonded phosphor thermometry applications in humid and low-temperature environments.

Enhancement of radiation tolerance in GaAs/AlGaAs core–shell and InP nanowires

NASA Astrophysics Data System (ADS)

Li, Fajun; Xie, Xiaolong; Gao, Qian; Tan, Liying; Zhou, Yanping; Yang, Qingbo; Ma, Jing; Fu, Lan; Tan, Hark Hoe; Jagadish, Chennupati

2018-06-01

Radiation effects on semiconductor nanowires (NWs) have attracted the attention of the research community due to their potential applications in space and atomic fields. The effective implementation of NW devices in a radiation environment is a matter of concern. Here, the photoluminescence (PL) and time-resolved PL (TRPL) measurements were performed on both GaAs and InP NWs at room temperature before and after 1 MeV H+ irradiation with fluences ranging from 1 × 1011 to 5 × 1013 p cm‑2. It is found that the degradation of lifetime is size-dependent, and typically the minority carrier lifetime damage coefficient is closely correlated with the material and NW diameter. Compared to GaAs and InP bulk material counterparts, the lifetime damage coefficient of NWs decreases by a factor of about one order of magnitude. After irradiation, GaAs NWs with a smaller diameter show a much lower lifetime damage coefficient while InP NWs show an increase in carrier radiative lifetime. The increased size-dependent radiation hardness is mainly attributed to the defect sink effect and/or the improvement of a room temperature dynamic annealing mechanism of the NWs. The InP NWs also showed higher radiation tolerance than GaAs NWs.

Enhancement of radiation tolerance in GaAs/AlGaAs core-shell and InP nanowires.

PubMed

Li, Fajun; Xie, Xiaolong; Gao, Qian; Tan, Liying; Zhou, Yanping; Yang, Qingbo; Ma, Jing; Fu, Lan; Tan, Hark Hoe; Jagadish, Chennupati

2018-06-01

Radiation effects on semiconductor nanowires (NWs) have attracted the attention of the research community due to their potential applications in space and atomic fields. The effective implementation of NW devices in a radiation environment is a matter of concern. Here, the photoluminescence (PL) and time-resolved PL (TRPL) measurements were performed on both GaAs and InP NWs at room temperature before and after 1 MeV H + irradiation with fluences ranging from 1 × 10 11 to 5 × 10 13 p cm -2 . It is found that the degradation of lifetime is size-dependent, and typically the minority carrier lifetime damage coefficient is closely correlated with the material and NW diameter. Compared to GaAs and InP bulk material counterparts, the lifetime damage coefficient of NWs decreases by a factor of about one order of magnitude. After irradiation, GaAs NWs with a smaller diameter show a much lower lifetime damage coefficient while InP NWs show an increase in carrier radiative lifetime. The increased size-dependent radiation hardness is mainly attributed to the defect sink effect and/or the improvement of a room temperature dynamic annealing mechanism of the NWs. The InP NWs also showed higher radiation tolerance than GaAs NWs.

The Effect of Prior Concussion History on Dual-Task Gait following a Concussion.

PubMed

Howell, David R; Beasley, Michael; Vopat, Lisa; Meehan, William P

2017-02-15

Sustaining repeated concussions has been associated with worse outcomes after additional injuries. This effect has been identified using symptom inventories and neurocognitive tests; however, few investigations have examined how a prior concussion history affects gait soon after a subsequent concussion. We examined the gait characteristics of athletes with no documented concussion history (n = 31), athletes recovering from their first lifetime concussion (n = 15), and athletes recovering from their second or greater lifetime concussion (n = 22). All participants completed a single-task and dual-task gait examination, a medical history questionnaire, and a postconcussion symptom scale. Multivariate analyses of covariance (MANCOVA) models were used to evaluate mean gait differences among groups, and Spearman's ρ analyses were used to assess correlations between the number of lifetime concussions and gait characteristics. Patients reporting to the clinic with their second or greater lifetime concussion demonstrated smaller stride lengths than healthy control participants during dual-task walking (p = 0.01; d = 0.70). A moderate but insignificant correlation was detected between dual-task gait speed and the number of prior concussions (ρ = 0.41, p = 0.07). These results indicate that a cumulative effect of concussions across the lifetime may contribute to worsening dual-task dynamic motor function after concussion.

Lifetime risk of stroke in young-aged and middle-aged Chinese population: the Chinese Multi-Provincial Cohort Study

PubMed Central

Wang, Ying; Liu, Jing; Wang, Wei; Wang, Miao; Qi, Yue; Xie, Wuxiang; Li, Yan; Sun, Jiayi; Liu, Jun; Zhao, Dong

2016-01-01

Objective: Stroke is a major cause of premature death in China. Early prevention of stroke requires a more effective method to differentiate the stroke risk among young-aged and middle-aged individuals than the 10-year risk of cardiovascular disease. This study aimed to establish a lifetime stroke risk model and risk charts for the young-aged and middle-aged population in China. Methods: The Chinese Multi-Provincial Cohort Study participants (n = 21 953) aged 35–84 years without cardiovascular disease at baseline were followed for 18 years (263 016 person-years). Modified Kaplan–Meier method was used to estimate the mean lifetime stroke risk up to age of 80 years and the lifetime stroke risk according to major stroke risk factors for the population aged 35–60 years. Results: A total of 917 participants developed first-ever strokes. For the participants aged 35–40 years (98 stroke cases), the lifetime stroke risk was 18.0 and 14.7% in men and women, respectively. Blood pressure most effectively discriminated the lifetime stroke risk. The lifetime risk of stroke for the individuals with all risk factors optimal was 8–10 times lower compared with those with two or more high risk factors at age 35–60 years at baseline. Conclusion: In young-aged and middle-aged population, the lifetime stroke risk will keep very low if major risk factors especially blood pressure level is at optimal levels, but the risk substantially increases even with a slight elevation of major risk factors, which could not be identified using 10-year risk estimation. PMID:27512963

The influences of parental divorce and maternal-versus-paternal alcohol abuse on offspring lifetime suicide attempt.

PubMed

Thompson, Ronald G; Alonzo, Dana; Hu, Mei-Chen; Hasin, Deborah S

2017-05-01

Research indicates that parental divorce and parental alcohol abuse independently increase likelihood of offspring lifetime suicide attempt. However, when experienced together, only parental alcohol abuse significantly increased odds of suicide attempt. It is unclear to what extent differences in the effect of maternal versus paternal alcohol use exist on adult offspring lifetime suicide attempt risk. This study examined the influences of parental divorce and maternal-paternal histories of alcohol problems on adult offspring lifetime suicide attempt. The sample consisted of participants from the 2001-2002 National Epidemiological Survey on Alcohol and Related Conditions. The simultaneous effect of childhood or adolescent parental divorce and maternal and paternal history of alcohol problems on offspring lifetime suicide attempt was estimated using a logistic regression model with an interaction term for demographics and parental history of other emotional and behavioural problems. Parental divorce and maternal-paternal alcohol problems interacted to differentially influence the likelihood of offspring lifetime suicide attempt. Experiencing parental divorce and either maternal or paternal alcohol problems nearly doubled the likelihood of suicide attempt. Divorce and history of alcohol problems for both parents tripled the likelihood. Individuals who experienced parental divorce as children or adolescents and who have a parent who abuses alcohol are at elevated risk for lifetime suicide attempt. These problem areas should become a routine part of assessment to better identify those at risk for lifetime suicide attempt and to implement early and targeted intervention to decrease such risk. [Thompson RG Jr,Alonzo D, Hu M-C, Hasin DS. The influences of parental divorce and maternal-versus-paternal alcohol abuse on offspringlifetime suicide attempt. Drug Alcohol Rev 2017;36:408-414]. © 2016 Australasian Professional Society on Alcohol and other Drugs.

Influence of Number of Implants and Attachment Type on Stress Distribution in Mandibular Implant-Retained Overdentures: Finite Element Analysis

PubMed Central

El-Anwar, Mohamed I.; El-Taftazany, Eman A.; Hamed, Hamdy A.; ElHay, Mohamed A. Abd

2017-01-01

AIM: This study aimed to compare the stresses generated by using two or four root form dental implants supporting mandibular overdentures that were retained with ball and locator attachments. METHODS: Under ANSYS environment, four 3D finite element models were prepared. These models simulated complete overdentures supported by two or four implants with either ball or locator attachments as a connection mechanism. The models’ components were created by CAD/CAM package then were imported to ANSYS. Load of 100 N was applied at the right premolar/molar region vertically and at an oblique angle of 110° from lingual direction. RESULTS: Within the conditions of this research, in all cases, it was found that cortical and cancellous bone regions were the least to be stressed. Also, the ball attachment produced higher stresses. CONCLUSION: Caps deformation and stresses are negligible in cases of using locator attachment in comparison to ball attachments. This may indicate longer lifetime and less repair/maintenance operations in implant overdentures retained by locator attachments. Although the study revealed that bone was insensitive to a number of implants or attachment type, it may be recommended to use two implants in the canine region than using four, where the locator attachments were found to be better. PMID:28507636

Influence of Number of Implants and Attachment Type on Stress Distribution in Mandibular Implant-Retained Overdentures: Finite Element Analysis.

PubMed

El-Anwar, Mohamed I; El-Taftazany, Eman A; Hamed, Hamdy A; ElHay, Mohamed A Abd

2017-04-15

This study aimed to compare the stresses generated by using two or four root form dental implants supporting mandibular overdentures that were retained with ball and locator attachments. Under ANSYS environment, four 3D finite element models were prepared. These models simulated complete overdentures supported by two or four implants with either ball or locator attachments as a connection mechanism. The models' components were created by CAD/CAM package then were imported to ANSYS. Load of 100 N was applied at the right premolar/molar region vertically and at an oblique angle of 110° from lingual direction. Within the conditions of this research, in all cases, it was found that cortical and cancellous bone regions were the least to be stressed. Also, the ball attachment produced higher stresses. Caps deformation and stresses are negligible in cases of using locator attachment in comparison to ball attachments. This may indicate longer lifetime and less repair/maintenance operations in implant overdentures retained by locator attachments. Although the study revealed that bone was insensitive to a number of implants or attachment type, it may be recommended to use two implants in the canine region than using four, where the locator attachments were found to be better.

Impact of a boron rich layer on minority carrier lifetime degradation in boron spin-on dopant diffused n-type crystalline silicon solar cells

NASA Astrophysics Data System (ADS)

Singha, Bandana; Singh Solanki, Chetan

2016-03-01

In the production of n-type crystalline silicon solar cells with boron diffused emitters, the formation of a boron rich layer (BRL) is a common phenomenon and is largely responsible for bulk lifetime degradation. The phenomenon of BRL formation during diffusion of boron spin-on dopant and its impact on bulk lifetime degradation are investigated in this work. The BRL formed beneath the borosilicate glass layer has thicknesses varying from 10 nm-150 nm depending on the diffusion conditions. The effective and bulk minority carrier lifetimes, measured with Al2O3 deposited layers and a quinhydron-methanol solution, show that carrier lifetime degradation is proportional to the BRL thicknesses and their surface recombination velocities. The controlled diffusion processes and different oxidation techniques used in this work can partially reduce the BRL thickness and improve carrier lifetime by more than 10%. But for BRL thicknesses higher than 50 nm, different etching techniques further lower the carrier lifetime and the degradation in the device cannot be recovered.

Towards an In-Beam Measurement of the Neutron Lifetime to 1 Second

NASA Astrophysics Data System (ADS)

Mulholland, Jonathan

2014-03-01

A precise value for the neutron lifetime is required for consistency tests of the Standard Model and is an essential parameter in the theory of Big Bang Nucleosynthesis. A new measurement of the neutron lifetime using the in-beam method is planned at the National Institute of Standards and Technology Center for Neutron Research. The systematic effects associated with the in-beam method are markedly different than those found in storage experiments utilizing ultracold neutrons. Experimental improvements, specifically recent advances in the determination of absolute neutron fluence, should permit an overall uncertainty of 1 second on the neutron lifetime. The dependence of the primordial mass fraction on the neutron lifetime, technical improvements of the in-beam technique, and the path toward improving the precision of the new measurement will be discussed.

Interaction Effects between Maternal Lifetime Depressive/Anxiety Disorders and Correlates of Children's Externalizing Symptoms

ERIC Educational Resources Information Center

Piche, Genevieve; Bergeron, Lise; Cyr, Mireille; Berthiaume, Claude

2011-01-01

We investigated the interaction effects between mother's lifetime depressive/anxiety disorders and psychosocial correlates of 6 to 11 year-old children's self-reported externalizing symptoms in the Quebec Child Mental Health Survey. A representative subsample of 1,490 Quebec children aged 6 to 11 years was selected from the original sample. We…

Quasiclassical calculations of blackbody-radiation-induced depopulation rates and effective lifetimes of Rydberg nS, nP, and nD alkali-metal atoms with n{<=}80

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

Beterov, I. I.; Ryabtsev, I. I.; Tretyakov, D. B.

2009-05-15

Rates of depopulation by blackbody radiation (BBR) and effective lifetimes of alkali-metal nS, nP, and nD Rydberg states have been calculated in a wide range of principal quantum numbers n{<=}80 at the ambient temperatures of 77, 300, and 600 K. Quasiclassical formulas were used to calculate the radial matrix elements of the dipole transitions from Rydberg states. Good agreement of our numerical results with the available theoretical and experimental data has been found. We have also obtained simple analytical formulas for estimates of effective lifetimes and BBR-induced depopulation rates, which well agree with the numerical data.

Shear-flexible finite-element models of laminated composite plates and shells

NASA Technical Reports Server (NTRS)

Noor, A. K.; Mathers, M. D.

1975-01-01

Several finite-element models are applied to the linear static, stability, and vibration analysis of laminated composite plates and shells. The study is based on linear shallow-shell theory, with the effects of shear deformation, anisotropic material behavior, and bending-extensional coupling included. Both stiffness (displacement) and mixed finite-element models are considered. Discussion is focused on the effects of shear deformation and anisotropic material behavior on the accuracy and convergence of different finite-element models. Numerical studies are presented which show the effects of increasing the order of the approximating polynomials, adding internal degrees of freedom, and using derivatives of generalized displacements as nodal parameters.

Unexpected finite size effects in interfacial systems: Why bigger is not always better—Increase in uncertainty of surface tension with bulk phase width

NASA Astrophysics Data System (ADS)

Longford, Francis G. J.; Essex, Jonathan W.; Skylaris, Chris-Kriton; Frey, Jeremy G.

2018-06-01

We present an unexpected finite size effect affecting interfacial molecular simulations that is proportional to the width-to-surface-area ratio of the bulk phase Ll/A. This finite size effect has a significant impact on the variance of surface tension values calculated using the virial summation method. A theoretical derivation of the origin of the effect is proposed, giving a new insight into the importance of optimising system dimensions in interfacial simulations. We demonstrate the consequences of this finite size effect via a new way to estimate the surface energetic and entropic properties of simulated air-liquid interfaces. Our method is based on macroscopic thermodynamic theory and involves comparing the internal energies of systems with varying dimensions. We present the testing of these methods using simulations of the TIP4P/2005 water forcefield and a Lennard-Jones fluid model of argon. Finally, we provide suggestions of additional situations, in which this finite size effect is expected to be significant, as well as possible ways to avoid its impact.

Validation of High Displacement Piezoelectric Actuator Finite Element Models

NASA Technical Reports Server (NTRS)

Taleghani, B. K.

2000-01-01

The paper presents the results obtained by using NASTRAN(Registered Trademark) and ANSYS(Regitered Trademark) finite element codes to predict doming of the THUNDER piezoelectric actuators during the manufacturing process and subsequent straining due to an applied input voltage. To effectively use such devices in engineering applications, modeling and characterization are essential. Length, width, dome height, and thickness are important parameters for users of such devices. Therefore, finite element models were used to assess the effects of these parameters. NASTRAN(Registered Trademark) and ANSYS(Registered Trademark) used different methods for modeling piezoelectric effects. In NASTRAN(Registered Trademark), a thermal analogy was used to represent voltage at nodes as equivalent temperatures, while ANSYS(Registered Trademark) processed the voltage directly using piezoelectric finite elements. The results of finite element models were validated by using the experimental results.

Single speckle SRS threshold as determined by electron trapping, collisions and speckle duration

NASA Astrophysics Data System (ADS)

Rose, Harvey; Daughton, William; Yin, Lin; Langdon, Bruce

2008-11-01

Speckle SRS intensity threshold has been shown to increase with spatial dimension, D, because both diffraction and trapped electron escape rate increase with D, though the net effect is to substantially decrease the threshold compared to 1D linear gain calculations. On the other hand, the apparent threshold appears to decrease with integration time in PIC simulations. We present an optimum nonlinearly resonant calculation of the SRS threshold, taking into account large fluctuations of the SRS seed reflectivity, R0. Such fluctuations, absent in 1D, are caused by a gap in the linear reflectivity gain spectrum which leads to an exponential probability distribution for R0. While the SRS threshold intensity is of course finite, these fluctuations lead to a decrease of apparent threshold with increasing speckle lifetime. L. Yin et al., Physics of Plasmas 15, 013109 (2008). D. S. Montgomery et al., 9, 2311(2002). Bruce Langdon et al., 38^th Anomalous Absorption Conference (2008). Harvey A. Rose, Physics of Plasmas 10, 1468 (2003). Harvey A. Rose and L. Yin, Physics of Plasmas 15, 042311 (2008)., Harvey A. Rose and David A. Russell, Phys. Plasma 8, 4784 (2001).

Trap Model for Clogging and Unclogging in Granular Hopper Flows.

PubMed

Nicolas, Alexandre; Garcimartín, Ángel; Zuriguel, Iker

2018-05-11

Granular flows through narrow outlets may be interrupted by the formation of arches or vaults that clog the exit. These clogs may be destroyed by vibrations. A feature which remains elusive is the broad distribution p(τ) of clog lifetimes τ measured under constant vibrations. Here, we propose a simple model for arch breaking, in which the vibrations are formally equivalent to thermal fluctuations in a Langevin equation; the rupture of an arch corresponds to the escape from an energy trap. We infer the distribution of trap depths from experiments made in two-dimensional hoppers. Using this distribution, we show that the model captures the empirically observed heavy tails in p(τ). These heavy tails flatten at large τ, consistently with experimental observations under weak vibrations. But, here, we find that this flattening is systematic, which casts doubt on the ability of gentle vibrations to restore a finite outflow forever. The trap model also replicates recent results on the effect of increasing gravity on the statistics of clog formation in a static silo. Therefore, the proposed framework points to a common physical underpinning to the processes of clogging and unclogging, despite their different statistics.

Calibration of the NEXT-White Detector using $$^{83m}\\mathrm{Kr}$$ Decays

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

Martínez-Lema, G.; et al.

The NEXT-White (NEW) detector is currently the largest radio-pure high pressure gas xenon time projection chamber with electroluminescent readout in the world. NEXT-White has been operating at Laboratorio Subterr\\'aneo de Canfranc (LSC) since October 2016. This paper describes the calibrations performed withmore » $$^{83m}\\mathrm{Kr}$$ decays during a long run taken from March to November 2017 (Run II). Krypton calibrations are used to correct for the finite drift-electron lifetime as well as for the dependence of the measured energy on the event position which is mainly caused by variations in solid angle coverage. After producing calibration maps to correct for both effects we measure an excellent energy resolution for 41.5 keV point-like deposits of (4.55 $$\\pm$$ 0.01) % FWHM in the full chamber and (3.88 $$\\pm$$ 0.04) % FWHM in a restricted fiducial volume. Using naive 1/$$\\sqrt{E}$$ scaling, these values translate into FWHM resolutions of (0.592 $$\\pm$$ 0.001) % FWHM and (0.504 $$\\pm$$ 0.005) % at the $$Q_{\\beta\\beta}$$ energy of xenon double beta decay (2458 keV), well within range of our target value of 1%.« less

Uniaxial and Multiaxial Fatigue Life Prediction of the Trabecular Bone Based on Physiological Loading: A Comparative Study.

PubMed

Fatihhi, S J; Harun, M N; Abdul Kadir, Mohammed Rafiq; Abdullah, Jaafar; Kamarul, T; Öchsner, Andreas; Syahrom, Ardiyansyah

2015-10-01

Fatigue assessment of the trabecular bone has been developed to give a better understanding of bone properties. While most fatigue studies are relying on uniaxial compressive load as the method of assessment, in various cases details are missing, or the uniaxial results are not very realistic. In this paper, the effect of three different load histories from physiological loading applied on the trabecular bone were studied in order to predict the first failure surface and the fatigue lifetime. The fatigue behaviour of the trabecular bone under uniaxial load was compared to that of multiaxial load using a finite element simulation. The plastic strain was found localized at the trabecular structure under multiaxial load. On average, applying multiaxial loads reduced more than five times the fatigue life of the trabecular bone. The results provide evidence that multiaxial loading is dominated in the low cycle fatigue in contrast to the uniaxial one. Both bone volume fraction and structural model index were best predictors of failure (p < 0.05) in fatigue for both types of loading, whilst uniaxial loading has indicated better values in most cases.

Trap Model for Clogging and Unclogging in Granular Hopper Flows

NASA Astrophysics Data System (ADS)

Nicolas, Alexandre; Garcimartín, Ángel; Zuriguel, Iker

2018-05-01

Granular flows through narrow outlets may be interrupted by the formation of arches or vaults that clog the exit. These clogs may be destroyed by vibrations. A feature which remains elusive is the broad distribution p (τ ) of clog lifetimes τ measured under constant vibrations. Here, we propose a simple model for arch breaking, in which the vibrations are formally equivalent to thermal fluctuations in a Langevin equation; the rupture of an arch corresponds to the escape from an energy trap. We infer the distribution of trap depths from experiments made in two-dimensional hoppers. Using this distribution, we show that the model captures the empirically observed heavy tails in p (τ ). These heavy tails flatten at large τ , consistently with experimental observations under weak vibrations. But, here, we find that this flattening is systematic, which casts doubt on the ability of gentle vibrations to restore a finite outflow forever. The trap model also replicates recent results on the effect of increasing gravity on the statistics of clog formation in a static silo. Therefore, the proposed framework points to a common physical underpinning to the processes of clogging and unclogging, despite their different statistics.

Numerical and experimental investigation into the subsequent thermal cycling during selective laser melting of multi-layer 316L stainless steel

NASA Astrophysics Data System (ADS)

Liu, Yang; Zhang, Jian; Pang, Zhicong

2018-01-01

Subsequent thermal cycling (STC), as the unique thermal behavior during the multi-layer manufacturing process of selective laser melting (SLM), brings about unique microstructure of the as-produced parts. A multi-layer finite element (FE) model was proposed to study the STC along with a contrast experiment. The FE simulational results show that as layer increases, the maximum temperature, dimensions and liquid lifetime of the molten pool increase, while the heating and cooling rates decrease. The maximum temperature point shifts into the molten pool, and central of molten pool shifts backward. The neighborly underlying layer can be remelted thoroughly when laser irradiates a powder layer, thus forming an excellent bonding between neighbor layers. The contrast experimental results between the single-layer and triple-layer samples show that grains in of latter become coarsen and tabular along the height direction compared with those of the former. Moreover, this effect become more serious in 2nd and 1st layers in the triple-layer sample. All the above illustrate that the STC has an significant influence on the thermal behavior during SLM process, and thus affects the microstructure of SLMed parts.

Measuring and modeling the lifetime of nitrous oxide including its variability: NITROUS OXIDE AND ITS CHANGING LIFETIME

DOE PAGES

Prather, Michael J.; Hsu, Juno; DeLuca, Nicole M.; ...

2015-06-05

The lifetime of nitrous oxide, the third‐most‐important human‐emitted greenhouse gas, is based to date primarily on model studies or scaling to other gases. This work calculates a semiempirical lifetime based on Microwave Limb Sounder satellite measurements of stratospheric profiles of nitrous oxide, ozone, and temperature; laboratory cross‐section data for ozone and molecular oxygen plus kinetics for O(1D); the observed solar spectrum; and a simple radiative transfer model. The result is 116 ± 9 years. The observed monthly‐to‐biennial variations in lifetime and tropical abundance are well matched by four independent chemistry‐transport models driven by reanalysis meteorological fields for the period of observation (2005–2010), butmore » all these models overestimate the lifetime due to lower abundances in the critical loss region near 32 km in the tropics. These models plus a chemistry‐climate model agree on the nitrous oxide feedback factor on its own lifetime of 0.94 ± 0.01, giving N2O perturbations an effective residence time of 109 years. Combining this new empirical lifetime with model estimates of residence time and preindustrial lifetime (123 years) adjusts our best estimates of the human‐natural balance of emissions today and improves the accuracy of projected nitrous oxide increases over this century.« less

Study of the high pressure effect on nanoparticles GdVO4: Eu3+ optical properties

NASA Astrophysics Data System (ADS)

Jovanić, B. R.; Bettinelli, M.; Piccinelli, F.; Radenković, B.; Despotović-Zrakić, M.; Bogdanović, Z.

2015-07-01

This study considers the effects of hydrostatic pressure on the line position and fluorescence lifetime τ for 5D0 → 7F2 transitions in GdVO4: Eu3+ nanocrystals. The results indicate that the pressure induced the red shift toward longer wavelengths for all the considered lines with different rate. The fluorescence lifetime τ nonlinearly decreases with pressure in the considered pressure range. High pressure induced the fluorescence lifetime τ that can be explained with a simple theoretical model. The measured line position and τ are in a satisfactory agreement with the theoretical calculations.

Time-resolved photoluminescence investigation of (Mg, Zn) O alloy growth on a non-polar plane

NASA Astrophysics Data System (ADS)

Mohammed Ali, Mohammed Jassim; Chauveau, J. M.; Bretagnon, T.

2018-04-01

Excitons recombination dynamics in ZnMgO alloy have been studied by time-resolved photoluminescence according to temperature. At low temperature, localisation effects of the exciton are found to play a significant role. The photoluminescence (PL) decays are bi-exponential. The short lifetime has a constant value, whereas the long lifetime shows a dependency with temperature. For temperature higher than 100 K the declines show a mono-exponential decay. The PL declines are dominated by non-radiative process at temperatures above 150 K. The PL lifetime dependancy with temperature is analysed using a model including localisation effects and non-radiative recombinations.

Finite-nuclear-size contribution to the g factor of a bound electron: Higher-order effects

NASA Astrophysics Data System (ADS)

Karshenboim, Savely G.; Ivanov, Vladimir G.

2018-02-01

A precision comparison of theory and experiments on the g factor of an electron bound in a hydrogenlike ion with a spinless nucleus requires a detailed account of finite-nuclear-size contributions. While the relativistic corrections to the leading finite-size contribution are known, the higher-order effects need an additional consideration. Two results are presented in the paper. One is on the anomalous-magnetic-moment correction to the finite-size effects and the other is due to higher-order effects in Z α m RN . We also present here a method to relate the contributions to the g factor of a bound electron in a hydrogenlike atom to its energy within a nonrelativistic approach.

Radiative lifetimes of the CN (A 2 Pi i) electronic state

NASA Technical Reports Server (NTRS)

Lu, Richang; Huang, Yuhui; Halpern, Joshua B.

1992-01-01

Radiative lifetimes have been measured for CN (A 2 Pi i v-prime = 2...7). Ground-state radicals formed in the 193 nm photolysis of C2N2 and ClCN were excited to A 2 Pi i v-prime = 2...7 vibrational levels. The decay was monitored by following the fluorescence. Cascading effects were eliminated by working at low pressures and monitoring emission from a single vibrational band. Quenching rates and zero-pressure radiative lifetimes were obtained from Stern-Volmer plots. The lifetimes are significantly lower than previous measurements and theoretical calculations for vibrational states v-prime over 2.

Influence of tellurite on lifetime for samarium doped lanthanum lead borate glass

NASA Astrophysics Data System (ADS)

Madhu, A.; Eraiah, B.

2018-04-01

Samarium substituted tellurium lanthanum lead borate glass is prepared using melt quenching technique. Luminescence spectra have been recorded upon excitation with 402 nm various transitions from 4G5/2 level, for samarium doped tellurite glasses are studied and also lifetime for all the samples exhibit single exponential behaviour of decay curve. Luminescence spectra of present glasses show quenching effect due to cross-relation channels of samarium ions. The lifetime of glass samples decrease as the tellurite concentration is decreased. So, it evidences that to attain longer lifetime for lasing material one can tune the host by selecting concentration of tellurite.

The effect of current reversal on coated titanium electrodes

NASA Astrophysics Data System (ADS)

Elnathan, Francis

Coated titanium electrodes have applications in the electrochemical industry, including water treatment and swimming pool chlorination. Current/polarity reverse electrolysis is a technique used for "self-cleaning" of the coated titanium anodes employed in water disinfection and treatment. However, the literature holds very little information about the effects of polarity reversal on these anodes. The present work appears to be the first to investigate coated titanium anodes in polarity reversal in a systematic method. Two commercial titanium electrodes (RuTi and IrTa) were studied. Polarity reversal was the main electrochemical technique employing a current density of 1200 A/m 2, except when current density was studied. The effects of NO 3-, SO42-, ClO4 -, HPO42-, CO32-, Mg2+ and Ca2+ on electrode lifetime were examined. Analysis of the electrochemical results showed that plateau time (tau p), for gas evolution, is highly important to the lifetime of the coated titanium anodes. The effects of three electrolysis variables on the coated titanium anode life were examined. Current density was observed to have an inverse relationship with anode life while reversal cycle time had a direct relation with lifetime. NaCl concentration had no discernible effect. In general, the RuTi electrode exhibited longer lifetimes than IrTa except for a few specific conditions. The influence of the concentration of five anions (NO3-, SO42-, ClO 4-, HPO42-, and CO3 2-) was determined. Changing the composition and concentration of anions affected the lifetimes of the two electrodes, especially nitrate, hydrogen phosphate and carbonate. The lifetime of IrTa was highest in nitrate, and increased as a function of nitrate concentration. The service life of RuTi was highest in hydrogen phosphate, and increased with increasing hydrogen phosphate concentration. Lifetime of both anodes decreased with increasing carbonate ions. The effects of Mg2+ and Ca2+ on electrode lifetime were examined with three anions (NO3-, HPO42-, ClO4-) electrolytes. While there were numerous effects and interactions between Mg2+ or Ca2+ and anions on lifetime, these effects were found to mainly affect the amount of time the electrodes spent in the charging and discharging reactions. The times related to gas evolution (which is the plateau time, tau p) were found to be strikingly similar. The charging times (tau C) which are related to adsorption and desorption of species were not also any significantly different. Coating dissolution, substrate and/or coating passivation mechanisms were identified as being responsible for coated titanium anode failure in current reverse and hard water electrolysis. IrTa is believed to have failed predominantly by the dissolution mechanism in nitrate, hydrogen phosphate and perchlorate. RuTi failed predominantly by substrate and/or coating passivation in hydrogen phosphate, nitrate and carbonate. Anode failure is believed to be the result of plateau (taup) and charging (tauC)reactions occurring at the coating/electrolyte and/or substrate/coating interface. The tau p and tauC are useful determinants for the process of anode failure.

Competitions between Rayleigh-Taylor instability and Kelvin-Helmholtz instability with continuous density and velocity profiles

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

Ye, W. H.; He, X. T.; CAPT, Peking University, Beijing 100871

2011-02-15

In this research, competitions between Rayleigh-Taylor instability (RTI) and Kelvin-Helmholtz instability (KHI) in two-dimensional incompressible fluids within a linear growth regime are investigated analytically. Normalized linear growth rate formulas for both the RTI, suitable for arbitrary density ratio with continuous density profile, and the KHI, suitable for arbitrary density ratio with continuous density and velocity profiles, are obtained. The linear growth rates of pure RTI ({gamma}{sub RT}), pure KHI ({gamma}{sub KH}), and combined RTI and KHI ({gamma}{sub total}) are investigated, respectively. In the pure RTI, it is found that the effect of the finite thickness of the density transition layermore » (L{sub {rho}}) reduces the linear growth of the RTI (stabilizes the RTI). In the pure KHI, it is found that conversely, the effect of the finite thickness of the density transition layer increases the linear growth of the KHI (destabilizes the KHI). It is found that the effect of the finite thickness of the density transition layer decreases the ''effective'' or ''local'' Atwood number (A) for both the RTI and the KHI. However, based on the properties of {gamma}{sub RT}{proportional_to}{radical}(A) and {gamma}{sub KH}{proportional_to}{radical}(1-A{sup 2}), the effect of the finite thickness of the density transition layer therefore has a completely opposite role on the RTI and the KHI noted above. In addition, it is found that the effect of the finite thickness of the velocity shear layer (L{sub u}) stabilizes the KHI, and for the most cases, the combined effects of the finite thickness of the density transition layer and the velocity shear layer (L{sub {rho}=}L{sub u}) also stabilize the KHI. Regarding the combined RTI and KHI, it is found that there is a competition between the RTI and the KHI because of the completely opposite effect of the finite thickness of the density transition layer on these two kinds of instability. It is found that the competitions between the RTI and the KHI depend, respectively, on the Froude number, the density ratio of the light fluid to the heavy one, and the finite thicknesses of the density transition layer and the velocity shear layer. Furthermore, for the fixed Froude number, the linear growth rate ratio of the RTI to the KHI decreases with both the density ratio and the finite thickness of the density transition layer, but increases with the finite thickness of the velocity shear layer and the combined finite thicknesses of the density transition layer and the velocity shear layer (L{sub {rho}=}L{sub u}). In summary, our analytical results show that the effect of the finite thickness of the density transition layer stabilizes the RTI and the overall combined effects of the finite thickness of the density transition layer and the velocity shear layer (L{sub {rho}=}L{sub u}) also stabilize the KHI. Thus, it should be included in applications where the transition layer effect plays an important role, such as the formation of large-scale structures (jets) in high energy density physics and astrophysics and turbulent mixing.« less

The effect of hot phonons and coupled phonon-plasmon modes on scattering-induced NDR in quantum wells

NASA Astrophysics Data System (ADS)

Ridley, B. K.; Al-Mudares, M.

1988-04-01

We have extended our Monte Carlo simulation of scattering-induced NDR in Al. 8Ga 2As/GaAs quantum wells by including (a) the effect of hot phonons (b) coupled phonon-plasmon modes (c) degeneracy. Hot phonons were modelled using a phenomenological lifetime which we ranged from 3ps to 10ps. Coupled modes were modelled in the antiscreening approximation. Bulk-like modes were assumed in both cases. NDR is quenched if the phonon lifetime exceeds 7ps, but is little affected if the lifetime is 3ps. The effect of coupled modes is appreciable at a doping density of 10 18cm -3, virtually eliminating NDR, but at 10 17cm -3 the effect is much smaller. Including degeneracy has only a small effect on the results. We conclude that NDR is still possible at electron densities around 10 17cm -3.

Dynamical lifetimes of asteroids in retrograde orbits

NASA Astrophysics Data System (ADS)

Kankiewicz, Paweł; Włodarczyk, Ireneusz

2017-07-01

The population of known minor bodies in retrograde orbits (I > 90°) that are classified as asteroids is still growing. The aim of our study was to estimate the dynamical lifetimes of these bodies using the latest observational data, including astrometry and physical properties. We selected 25 asteroids with the best-determined orbital elements. We studied their dynamical evolution in the past and future for ±100 Myr (±1 Gyr for three particular cases). We first used orbit determination and cloning to produce swarms of test particles. These swarms were then input into long-term numerical integrations, and the orbital elements were averaged. Next, we collected the available thermal properties of our objects and we used them in an enhanced dynamical model with Yarkovsky forces. We also used a gravitational model for comparison. Finally, we estimated the median lifetimes of 25 asteroids. We found three objects whose retrograde orbits were stable with a dynamical lifetime τ ˜ 10-100 Myr. A large portion of the objects studied displayed smaller values of τ (τ ˜ 1 Myr). In addition, we studied the possible influence of the Yarkovsky effect on our results. We found that the Yarkovsky effect can have a significant influence on the lifetimes of asteroids in retrograde orbits. Because of the presence of this effect, it is possible that the median lifetimes of these objects are extended. Additionally, the changes in orbital elements, caused by Yarkovsky forces, appear to depend on the integration direction. To explain this more precisely, the same model based on new physical parameters, determined from future observations, will be required.

Electrogenerated Chemiluminescence and Fluorescence Lifetime Spatial Heterogeneity of Poly (2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene) in Presence of [6,6]-phenyl-C61-butyric Acid Methyl Ester

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

Geng, Hongwei; Pan, Shanlin; Hu, Dehong

In this paper, we studied the luminescence property and fluorescence lifetime mapping of MEH-PPV/PCBM system by using electrogenerated chemiluminescence (ECL) and time-correlated single photo counting (TC-SPC) technologies. The ECL results showed that the oxidation peak of MEH-PPV near 0.7 V (vs. SCE) and ECL response of films shifted positively towards 1.2 V when in the presence of PCBM. At the same time, the oxidation peak current density of MEH-PPV increases while the ECL response decreased with the loading of PCBM in the composite films. The fluorescence lifetime images clearly show that the lifetime fluctuation is effected by different substrates andmore » MEH-PPV/PCBM ratios. Meanwhile, the lifetime of MEH-PPV decreases with the increasing of film thickness. The lifetimes of MEH-PPV films on TiO2 substrate are lower than them of films on cover slips.« less

Interactive Effect of Immigration-Related Factors with Legal and Discrimination Acculturative Stress in Predicting Depression Among Asian American Immigrants.

PubMed

Singh, Shipra; Schulz, Amy Jo; Neighbors, Harold W; Griffith, Derek M

2017-08-01

This study examined the impact of discrimination and legal acculturative stress on Major Depression Episode lifetime among Asian American immigrants. It further examined the role of immigration related-factors (age at immigration, reason for immigration, and years spent in the U.S.) on the relationship of acculturative stress and Major Depression Episode lifetime. The National Latino and Asian American Study 2002-2003 dataset was used. The study findings were: (1) high discrimination and legal acculturative stress were associated with Major Depression Episode lifetime; (2) age at immigration buffered the relationship of discrimination acculturative stress and Major Depression Episode lifetime as well as the relationship of legal acculturative stress and Major Depression Episode lifetime; and (3) years spent in the U.S. buffered the relationship of discrimination acculturative stress and Major Depression Episode lifetime only. These findings highlight the complex relationship of factors that impact the mental health of the Asian American immigrants.

Two-component density functional theory calculations of positron lifetimes for small vacancy clusters in silicon

NASA Astrophysics Data System (ADS)

Makhov, D. V.; Lewis, Laurent J.

2005-05-01

The positron lifetimes for various vacancy clusters in silicon are calculated within the framework of the two-component electron-positron density functional theory. The effect of the trapped positron on the electron density and on the relaxation of the structure is investigated. Our calculations show that, contrary to the usual assumption, the positron-induced forces do not compensate in general for electronic inward forces. Thus, geometry optimization is required in order to determine positron lifetime accurately. For the monovacancy and the divacancy, the results of our calculations are in good agreement with the experimental positron lifetimes, suggesting that this approach gives good estimates of positron lifetimes for larger vacancy clusters, required for their correct identification with positron annihilation spectroscopy. As an application, our calculations show that fourfold trivacancies and symmetric fourfold tetravacancies have positron lifetimes similar to monovacancies and divacancies, respectively, and can thus be confused in the interpretation of positron annihilation experiments.

A literature review on fatigue and creep interaction

NASA Technical Reports Server (NTRS)

Chen, W. C.

1978-01-01

Life-time prediction methods, which are based on a number of empirical and phenomenological relationships, are presented. Three aspects are reviewed: effects of testing parameters on high temperature fatigue, life-time prediction, and high temperature fatigue crack growth.

Distributed Finite-Time Cooperative Control of Multiple High-Order Nonholonomic Mobile Robots.

PubMed

Du, Haibo; Wen, Guanghui; Cheng, Yingying; He, Yigang; Jia, Ruting

2017-12-01

The consensus problem of multiple nonholonomic mobile robots in the form of high-order chained structure is considered in this paper. Based on the model features and the finite-time control technique, a finite-time cooperative controller is explicitly constructed which guarantees that the states consensus is achieved in a finite time. As an application of the proposed results, finite-time formation control of multiple wheeled mobile robots is studied and a finite-time formation control algorithm is proposed. To show effectiveness of the proposed approach, a simulation example is given.

Global finite-time attitude consensus tracking control for a group of rigid spacecraft

NASA Astrophysics Data System (ADS)

Li, Penghua

2017-10-01

The problem of finite-time attitude consensus for multiple rigid spacecraft with a leader-follower architecture is investigated in this paper. To achieve the finite-time attitude consensus, at the first step, a distributed finite-time convergent observer is proposed for each follower to estimate the leader's attitude in a finite time. Then based on the terminal sliding mode control method, a new finite-time attitude tracking controller is designed such that the leader's attitude can be tracked in a finite time. Finally, a finite-time observer-based distributed control strategy is proposed. It is shown that the attitude consensus can be achieved in a finite time under the proposed controller. Simulation results are given to show the effectiveness of the proposed method.

Measuring and modeling the lifetime of nitrous oxide including its variability

NASA Astrophysics Data System (ADS)

Prather, Michael J.; Hsu, Juno; DeLuca, Nicole M.; Jackman, Charles H.; Oman, Luke D.; Douglass, Anne R.; Fleming, Eric L.; Strahan, Susan E.; Steenrod, Stephen D.; Søvde, O. Amund; Isaksen, Ivar S. A.; Froidevaux, Lucien; Funke, Bernd

2015-06-01

The lifetime of nitrous oxide, the third-most-important human-emitted greenhouse gas, is based to date primarily on model studies or scaling to other gases. This work calculates a semiempirical lifetime based on Microwave Limb Sounder satellite measurements of stratospheric profiles of nitrous oxide, ozone, and temperature; laboratory cross-section data for ozone and molecular oxygen plus kinetics for O(1D); the observed solar spectrum; and a simple radiative transfer model. The result is 116 ± 9 years. The observed monthly-to-biennial variations in lifetime and tropical abundance are well matched by four independent chemistry-transport models driven by reanalysis meteorological fields for the period of observation (2005-2010), but all these models overestimate the lifetime due to lower abundances in the critical loss region near 32 km in the tropics. These models plus a chemistry-climate model agree on the nitrous oxide feedback factor on its own lifetime of 0.94 ± 0.01, giving N2O perturbations an effective residence time of 109 years. Combining this new empirical lifetime with model estimates of residence time and preindustrial lifetime (123 years) adjusts our best estimates of the human-natural balance of emissions today and improves the accuracy of projected nitrous oxide increases over this century.

Fluorophore:dendrimer ratio impacts cellular uptake and intracellular fluorescence lifetime.

PubMed

Dougherty, Casey A; Vaidyanathan, Sriram; Orr, Bradford G; Banaszak Holl, Mark M

2015-02-18

G5-NH2-TAMRAn (n = 1-4, 5+, and 1.5(avg)) were prepared with n = 1-4 as a precise dye:dendrimer ratio, 5+ as a mixture of dendrimers with 5 or more dye per dendrimer, and 1.5(avg) as a Poisson distribution of dye:dendrimer ratios with a mean of 1.5 dye per dendrimer. The absorption intensity increased sublinearly with n whereas the fluorescence emission and lifetime decreased with an increasing number of dyes per dendrimer. Flow cytometry was employed to quantify uptake into HEK293A cells. Dendrimers with 2-4 dyes were found to have greater uptake than dendrimer with a single dye. Fluorescence lifetime imaging microscopy (FLIM) showed that the different dye:dendrimer ratio alone was sufficient to change the fluorescence lifetime of the material observed inside cells. We also observed that the lifetime of G5-NH2-TAMRA5+ increased when present in the cell as compared to solution. However, cells treated with G5-NH2-TAMRA1.5(avg) did not exhibit the high lifetime components present in G5-NH2-TAMRA1 and G5-NH2-TAMRA5+. In general, the effects of the dye:dendrimer ratio on fluorescence lifetime were of similar magnitude to environmentally induced lifetime shifts.

Measuring and modeling the lifetime of nitrous oxide including its variability

DOE PAGES

Prather, Michael J.; Hsu, Juno; DeLuca, Nicole M.; ...

2015-05-14

The lifetime of nitrous oxide, the third-most-important human-emitted greenhouse gas, is based to date primarily on model studies or scaling to other gases. This work calculates a semiempirical lifetime based on Microwave Limb Sounder satellite measurements of stratospheric profiles of nitrous oxide, ozone, and temperature; laboratory cross-section data for ozone and molecular oxygen plus kinetics for O( 1D); the observed solar spectrum; and a simple radiative transfer model. The result is 116 ± 9 years. The observed monthly-to-biennial variations in lifetime and tropical abundance are well matched by four independent chemistry-transport models driven by reanalysis meteorological fields for the periodmore » of observation (2005–2010), but all these models overestimate the lifetime due to lower abundances in the critical loss region near 32 km in the tropics. These models plus a chemistry-climate model agree on the nitrous oxide feedback factor on its own lifetime of 0.94 ± 0.01, giving N 2O perturbations an effective residence time of 109 years. Combining this new empirical lifetime with model estimates of residence time and preindustrial lifetime (123 years) adjusts our best estimates of the human-natural balance of emissions today and improves the accuracy of projected nitrous oxide increases over this century.« less

Lifetime indirect cost of childhood overweight and obesity: A decision analytic model.

PubMed

Sonntag, Diana; Ali, Shehzad; De Bock, Freia

2016-01-01

To estimate the indirect lifetime cost of childhood overweight and obesity for Germany. The lifetime cohort model consisted of two parts: (a) Model I used data from the German Interview and Examination Survey for Children on prevalence of BMI categories during childhood to evaluate BMI trajectories before the age of 18; and (b) Model II estimated lifetime excess indirect cost based on the history of childhood BMI. Indirect costs were defined as the opportunity cost of lost productivity due to mortality and morbidity and were identified through a systematic literature review. Our analysis showed that the majority of children with overweight and obesity remained in the same BMI category during their adult life, resulting in significant indirect lifetime costs. We estimated that overweight and obesity during childhood resulted in an excess lifetime cost per person of €4,209 (men) and €2,445 (women). For the current prevalent German population, the excess lifetime cost was €145 billion. Our study showed that childhood obesity results in significant economic burden on the society. Therefore, cost-effective strategies targeted at reducing the prevalence of obesity during the early years of life can significantly reduce both healthcare and nonhealthcare costs over the lifetime. © 2015 The Obesity Society.

Recoil distance lifetime measurements in 122,124Xe

NASA Astrophysics Data System (ADS)

Govil, I. M.; Kumar, A.; Iyer, H.; Li, H.; Garg, U.; Ghugre, S. S.; Johnson, T.; Kaczarowski, R.; Kharraja, B.; Naguleswaran, S.; Walpe, J. C.

1998-02-01

Lifetimes of the lower-excited states in 122,124Xe are measured using the recoil-distance Doppler-shift technique. The reactions 110Pd(16O,4n)122Xe and 110Pd(18O,4n)124Xe at a beam energy of 66 MeV were used for this experiment. The lifetimes of the 2+, 4+, 6+, and 8+ states of the ground state band were extracted using the computer code LIFETIME including the corrections due to the side feeding and the nuclear deorientation effects. The lifetime of the 2+ state in 122Xe agrees with the recoil distance method (RDM) measurements but for the 124Xe it does not agree with the RDM measurements but agrees with the Coulomb-excitation experiment. The measured B(E2) values for both the nuclei are compared with the standard algebraic and the multishell models.

Do thermal donors reduce the lifetimes of Czochralski-grown silicon crystals?

NASA Astrophysics Data System (ADS)

Miyamura, Y.; Harada, H.; Nakano, S.; Nishizawa, S.; Kakimoto, K.

2018-05-01

High-performance electronics require long carrier lifetimes within their silicon crystals. This paper reports the effects of thermal donors on the lifetimes of carriers in as-grown n-type silicon crystals grown by the Czochralski method. We grew silicon crystals with two different concentrations of thermal donors using the following two cooling processes: one was cooled with a 4-h halt after detaching the crystal from the melt, and the other was cooled continuously. The crystal grown with the cooling halt contained higher concentrations of thermal donors of the order of 1 × 1013 cm-3, while the crystal without the halt had no thermal donors. The measured bulk lifetimes were in the range of 15-18 ms. We concluded that thermal donors in Czochralski-grown silicon crystals do not act to reduce their lifetimes.

The Biological Underpinnings of Peer Victimization: Understanding Why and How the Effects of Bullying Can Last a Lifetime

ERIC Educational Resources Information Center

Vaillancourt, Tracy; Hymel, Shelley; McDougall, Patricia

2013-01-01

Recent research in the areas of neuroscience, neuroendocrinology, and genetics is reviewed providing convincing evidence for why and how the effects of bullying can last a lifetime. Specifically, the research reviewed herein indicates that (a) the brain experiences peer victimization in a similar way to physical pain, (b) peer victimization is…

The Effectiveness of a Constant Time Delay Procedure on Teaching Lifetime Sport Skills to Adolescents with Severe to Profound Intellectual Disabilities.

ERIC Educational Resources Information Center

Zhang, Jiabei; And Others

1995-01-01

A constant time delay (CTD) procedure was used to teach four adolescents with severe/profound intellectual disabilities to perform bowling, throwing, and putting. Results indicated that the adolescents could be effectively taught gross motor lifetime sport skills with the CTD procedure and that verbal description plus physical assistance could be…

The association between measurements of antimicrobial use and resistance in the faeces microbiota of finisher batches.

PubMed

Andersen, V D; DE Knegt, L V; Munk, P; Jensen, M S; Agersø, Y; Aarestrup, F M; Vigre, H

2017-10-01

The objectives were to present three approaches for calculating antimicrobial (AM) use in pigs that take into account the rearing period and rearing site, and to study the association between these measurements and phenotypical resistance and abundance of resistance genes in faeces samples from 10 finisher batches. The AM use was calculated relative to the rearing period of the batches as (i) 'Finisher Unit Exposure' at unit level, (ii) 'Lifetime Exposure' at batch level and (iii) 'Herd Exposure' at herd level. A significant effect on the occurrence of tetracycline resistance measured by cultivation was identified for Lifetime Exposure for the AM class: tetracycline. Furthermore, for Lifetime Exposure for the AM classes: macrolide, broad-spectrum penicillin, sulfonamide and tetracycline use as well as Herd Unit Exposure for the AM classes: aminoglycoside, lincosamide and tetracycline use, a significant effect was observed on the occurrence of genes coding for the AM resistance classes: aminoglycoside, lincosamide, macrolide, β-lactam, sulfonamide and tetracycline. No effect was observed for Finisher Unit Exposure. Overall, the study shows that Lifetime Exposure is an efficient measurement of AM use in finisher batches, and has a significant effect on the occurrence of resistance, measured either by cultivation or metagenomics.

Self-reported racial discrimination and endothelial reactivity to acute stress in women.

PubMed

Wagner, Julie A; Tennen, Howard; Finan, Patrick H; Ghuman, Nimrta; Burg, Matthew M

2013-08-01

This study investigated the effect of self-reported racial discrimination on endothelial responses to acute laboratory mental stress among post-menopausal women. One-hundred thirteen women (n = 94 self-identified as White and n = 19 self-identified as racial/ethnic minority), 43% with type 2 diabetes, reported lifetime experiences of racial/ethnic discrimination. Repeated assessments of flow-mediated dilation were performed at baseline, immediately after 5 min of mental arithmetic and at 20-min recovery. Both White and racial/ethnic minority women reported lifetime discrimination, with rates significantly higher among minorities. Self-reported lifetime discrimination was associated with attenuated flow-mediated dilation at recovery. Confounding variables, including clinical characteristics, mood, personality traits, other life stressors and general distress, did not better account for the effect of racial discrimination. Neither race/ethnicity nor diabetes status moderated the effect. The perceived stressfulness of the mental arithmetic was not associated with the endothelial response. In conclusion, self-reported lifetime discrimination is associated with attenuated endothelial recovery from acute mental stress. Elucidating the effects of discrimination and the biological mechanisms through which it affects the vasculature may suggest interventions to improve health. Copyright © 2012 John Wiley & Sons, Ltd.

Photo-acoustic spectroscopy and quantum efficiency of Yb{sup 3+} doped alumino silicate glasses

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

Kuhn, Stefan, E-mail: stefan.kuhn84@googlemail.com; Tiegel, Mirko; Herrmann, Andreas

2015-09-14

In this contribution, we analyze the effect of several preparation methods of Yb{sup 3+} doped alumino silicate glasses on their quantum efficiency by using photo-acoustic measurements in comparison to standard measurement methods including the determination via the fluorescence lifetime and an integrating sphere setup. The preparation methods focused on decreasing the OH concentration by means of fluorine-substitution and/or applying dry melting atmospheres, which led to an increase in the measured fluorescence lifetime. However, it was found that the influence of these methods on radiative properties such as the measured fluorescence lifetime alone does not per se give exact information aboutmore » the actual quantum efficiency of the sample. The determination of the quantum efficiency by means of fluorescence lifetime shows inaccuracies when refractive index changing elements such as fluorine are incorporated into the glass. Since fluorine not only eliminates OH from the glass but also increases the “intrinsic” radiative fluorescence lifetime, which is needed to calculate the quantum efficiency, it is difficult to separate lifetime quenching from purely radiative effects. The approach used in this contribution offers a possibility to disentangle radiative from non-radiative properties which is not possible by using fluorescence lifetime measurements alone and allows an accurate determination of the quantum efficiency of a given sample. The comparative determination by an integrating sphere setup leads to the well-known problem of reabsorption which embodies itself in the measurement of too low quantum efficiencies, especially for samples with small quantum efficiencies.« less

Lifetime and per year productivity of sows in four pig farms in the tropics of Mexico.

PubMed

Ek-Mex, Jesús Enrique; Segura-Correa, José Candelario; Alzina-López, Alejandro; Batista-Garcia, Laura

2015-03-01

The objectives of this study were to estimate the lifetime and per year productivity of sows and to determine the effect of some factor on those traits in four pig farms in the tropics of Mexico. Data from 7526 sows for lifetime number of piglets born alive per sow (LBA), lifetime kilograms of piglets at farrowing (LKF), number of piglets born alive per year (NPF/Y), and kilograms of piglets at farrowing per year (KPF/Y); and data from 7230 sows for lifetime number of piglets weaned (LPW), lifetime kilograms of piglets weaned (LKW), number of piglets weaned per year (NPW/Y), and kilograms of piglets weaned per year (KPW/Y) per sow were used. The statistical model for all traits included the fixed effects of farm, year of first farrowing, season of first farrowing, litter size at first farrowing, age at first farrowing, removal reason, simple interactions, and the error term. The means for LBA, LKF, NPF/Y, and KPF/Y were 45.1 piglets, 67.1 kg, 22.7 piglets, and 33.7 kg, respectively. The means for LPW, LKW, NPW/Y, and KPW/Y were 43.2 piglets, 251.9 kg, 21.5 piglets, and 125.1 kg, respectively. All factors were significant for all traits, except for age at first farrowing on LPW and LKW. Sows with large litter sizes and those that farrowed the first time, at an early age, had the highest lifetime and per year productivity. Therefore, more care and better management should be provided to those types of sows to improve the farms profit.

Surface induced phonon decay rates in thin film nano-structures

NASA Astrophysics Data System (ADS)

Photiadis, D. M.

2007-12-01

Nano-scale structure significantly impacts phonon transport and related phonon relaxation rates, with order of magnitude effects on the thermal conductivity of dielectric thin films and quantum wires, and even larger effects on the lifetimes of ultrasonic phonons of micro- (nano-) oscillators. In both cases, efforts to explain the data have been hampered by our lack of knowledge of the effects of confined dimensionality on phonon-phonon scattering rates. Using a phonon Boltzmann equation with appropriate boundary conditions on the free surfaces to take surface roughness into account, we have obtained an expression yielding phonon lifetimes in 2-D dielectric nanostructures(thin films) resulting from phonon-phonon scattering in conjunction with phonon-surface scattering. We present these theoretical results and, in the limit in which surface induced losses dominate, obtain explicit predictions for the phonon lifetimes. The predicted temperature dependence of the ultrason! ic loss does not explain the observed saturation of the loss at low temperatures(τ(T) → const), but does give results of the order of magnitude of measured ultrasonic lifetimes.

Enzymatic Transition States, Transition-State Analogs, Dynamics, Thermodynamics, and Lifetimes

PubMed Central

Schramm, Vern L.

2017-01-01

Experimental analysis of enzymatic transition-state structures uses kinetic isotope effects (KIEs) to report on bonding and geometry differences between reactants and the transition state. Computational correlation of experimental values with chemical models permits three-dimensional geometric and electrostatic assignment of transition states formed at enzymatic catalytic sites. The combination of experimental and computational access to transition-state information permits (a) the design of transition-state analogs as powerful enzymatic inhibitors, (b) exploration of protein features linked to transition-state structure, (c) analysis of ensemble atomic motions involved in achieving the transition state, (d) transition-state lifetimes, and (e) separation of ground-state (Michaelis complexes) from transition-state effects. Transition-state analogs with picomolar dissociation constants have been achieved for several enzymatic targets. Transition states of closely related isozymes indicate that the protein’s dynamic architecture is linked to transition-state structure. Fast dynamic motions in catalytic sites are linked to transition-state generation. Enzymatic transition states have lifetimes of femtoseconds, the lifetime of bond vibrations. Binding isotope effects (BIEs) reveal relative reactant and transition-state analog binding distortion for comparison with actual transition states. PMID:21675920

The effects of Project ALERT one year past curriculum completion.

PubMed

Ringwalt, Chris L; Clark, Heddy Kovach; Hanley, Sean; Shamblen, Stephen R; Flewelling, Robert L

2010-06-01

School-based drug prevention curricula constitute the nation's most prevalent strategy to prevent adolescent drug use. We evaluated the effects of one such curriculum, Project ALERT, on adolescent substance use. In particular, we sought to determine if a single effect on 30-day alcohol use, noted shortly following the completion of the 2-year program, could be detected 1 year later. We also looked for delayed effects on other outcomes of interest, namely lifetime alcohol use, and 30-day and lifetime use of cigarettes, marijuana, and inhalants. We employed a randomized controlled trial that used school as the unit of assignment. Thirty-four schools with grades 6-8 from 11 states completed the study. Seventy-one Project ALERT instructors taught 11 core lessons to sixth graders and 3 booster lessons to seventh graders. Students were assessed prior to the onset of the intervention, as sixth graders, after the completion of the 2-year curriculum, as seventh graders, and again 1 year later as eighth graders. This paper examines data from the pretest and final posttest. Using hierarchical nonlinear modeling, we found that our earlier effect on 30-day alcohol use did not persist. Further, we continued to find no effects for lifetime alcohol use and both the lifetime and 30-day use of cigarettes, marijuana, and inhalants. Our findings do not support the long-term effectiveness of Project ALERT, when delivered to sixth graders.

Effect of TiO2 nano fillers on the electrical conductivity of PSAN/TiO2 polymer nanocomposites

NASA Astrophysics Data System (ADS)

Ningaraju, S.; Munirathnamma, L. M.; Kumar, K. V. Aneesh; Ravikumar, H. B.

2016-05-01

The microstructural characterization of Polystyrene co-acrylonitrile and Titanium dioxide (PSAN/TiO2) nanocomposites has been performed by Positron Annihilation Lifetime Spectroscopy. The decrease of positron lifetime parameters viz. o-Ps lifetime (τ3) and free volume size (Vf) up to 0.6 wt% of TiO2 is attributed to the filling of free volume holes by TiO2 nanoparticles. The increased free volume size (Vf) after 0.6 wt% of TiO2 indicates the formation of interface due to TiO2 nanoclusters. The variation of electrical conductivity at the lower and higher concentration of TiO2 in (PSAN/TiO2) nanocomposites is attributed to the blocking effect and space charge effect respectively.

On the effects of grid ill-conditioning in three dimensional finite element vector potential magnetostatic field computations

NASA Technical Reports Server (NTRS)

Wang, R.; Demerdash, N. A.

1990-01-01

The effects of finite element grid geometries and associated ill-conditioning were studied in single medium and multi-media (air-iron) three dimensional magnetostatic field computation problems. The sensitivities of these 3D field computations to finite element grid geometries were investigated. It was found that in single medium applications the unconstrained magnetic vector potential curl-curl formulation in conjunction with first order finite elements produce global results which are almost totally insensitive to grid geometries. However, it was found that in multi-media (air-iron) applications first order finite element results are sensitive to grid geometries and consequent elemental shape ill-conditioning. These sensitivities were almost totally eliminated by means of the use of second order finite elements in the field computation algorithms. Practical examples are given in this paper to demonstrate these aspects mentioned above.

The effect of anisotropic heat transport on magnetic islands in 3-D configurations

NASA Astrophysics Data System (ADS)

Schlutt, M. G.; Hegna, C. C.

2012-08-01

An analytic theory of nonlinear pressure-induced magnetic island formation using a boundary layer analysis is presented. This theory extends previous work by including the effects of finite parallel heat transport and is applicable to general three dimensional magnetic configurations. In this work, particular attention is paid to the role of finite parallel heat conduction in the context of pressure-induced island physics. It is found that localized currents that require self-consistent deformation of the pressure profile, such as resistive interchange and bootstrap currents, are attenuated by finite parallel heat conduction when the magnetic islands are sufficiently small. However, these anisotropic effects do not change saturated island widths caused by Pfirsch-Schlüter current effects. Implications for finite pressure-induced island healing are discussed.

The modifier effects of chymotrypsin and trypsin enzymes on fluorescence lifetime distribution of "N-(1-pyrenyl)maleimide-bovine serum albumin" complex

NASA Astrophysics Data System (ADS)

Özyiğit, İbrahim Ethem; Karakuş, Emine; Pekcan, Önder

2016-02-01

Chymotrypsin and trypsin are the well known proteolytic enzymes, both of which are synthesized in the pancreas as their precursors - the inactive forms; chymotrypsinogen and trypsinogen - and then are released into the duodenum to cut proteins into smaller peptides. In this paper, the effects of activities of chymotrypsin and trypsin enzymes on fluorescence lifetime distributions of the substrat bovine serum albumin (BSA) modified with N-(1-pyrenyl)maleimide (PM) were examined. In the labeling study of BSA with PM, it is aimed to attach PM to the single free thiol (Cys34) and to all the free amine groups in accessible positions in order to produce excimers of pyrene planes of the possible highest amount to form the lifetime distributions in the widest range, that may show specifically distinguishing changes resulting from the activities of the proteases. The time resolved spectrofluorometer was used to monitor fluorescence decays, which were analyzed by using the exponential series method (ESM) to obtain the changes of lifetime distributions. After the exposure of the synthesized substrat PM-BSA to the enzymes, the fluorescence lifetime distributions exhibited different structures which were attributed to the different activities of the proteases.

Astrophysical implications of hypothetical stable TeV-scale black holes

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

Giddings, Steven B.; Mangano, Michelangelo L.

2008-08-01

We analyze macroscopic effects of TeV-scale black holes, such as could possibly be produced at the LHC, in what is regarded as an extremely hypothetical scenario in which they are stable and, if trapped inside Earth, begin to accrete matter. We examine a wide variety of TeV-scale gravity scenarios, basing the resulting accretion models on first-principles, basic, and well-tested physical laws. These scenarios fall into two classes, depending on whether accretion could have any macroscopic effect on the Earth at times shorter than the Sun's natural lifetime. We argue that cases with such an effect at shorter times than themore » solar lifetime are ruled out, since in these scenarios black holes produced by cosmic rays impinging on much denser white dwarfs and neutron stars would then catalyze their decay on time scales incompatible with their known lifetimes. We also comment on relevant lifetimes for astronomical objects that capture primordial black holes. In short, this study finds no basis for concerns that TeV-scale black holes from the LHC could pose a risk to Earth on time scales shorter than the Earth's natural lifetime. Indeed, conservative arguments based on detailed calculations and the best-available scientific knowledge, including solid astronomical data, conclude, from multiple perspectives, that there is no risk of any significance whatsoever from such black holes.« less

Prolonging fuel cell stack lifetime based on Pontryagin's Minimum Principle in fuel cell hybrid vehicles and its economic influence evaluation

NASA Astrophysics Data System (ADS)

Zheng, C. H.; Xu, G. Q.; Park, Y. I.; Lim, W. S.; Cha, S. W.

2014-02-01

The lifetime of fuel cell stacks is a major issue currently, especially for automotive applications. In order to take into account the lifetime of fuel cell stacks while considering the fuel consumption minimization in fuel cell hybrid vehicles (FCHVs), a Pontryagin's Minimum Principle (PMP)-based power management strategy is proposed in this research. This strategy has the effect of prolonging the lifetime of fuel cell stacks. However, there is a tradeoff between the fuel cell stack lifetime and the fuel consumption when this strategy is applied to an FCHV. Verifying the positive economic influence of this strategy is necessary in order to demonstrate its superiority. In this research, the economic influence of the proposed strategy is assessed according to an evaluating cost which is dependent on the fuel cell stack cost, the hydrogen cost, the fuel cell stack lifetime, and the lifetime prolonging impact on the fuel cell stack. Simulation results derived from the proposed power management strategy are also used to evaluate the economic influence. As a result, the positive economic influence of the proposed PMP-based power management strategy is proved for both current and future FCHVs.

Empirical membrane lifetime model for heavy duty fuel cell systems

NASA Astrophysics Data System (ADS)

Macauley, Natalia; Watson, Mark; Lauritzen, Michael; Knights, Shanna; Wang, G. Gary; Kjeang, Erik

2016-12-01

Heavy duty fuel cells used in transportation system applications such as transit buses expose the fuel cell membranes to conditions that can lead to lifetime-limiting membrane failure via combined chemical and mechanical degradation. Highly durable membranes and reliable predictive models are therefore needed in order to achieve the ultimate heavy duty fuel cell lifetime target of 25,000 h. In the present work, an empirical membrane lifetime model was developed based on laboratory data from a suite of accelerated membrane durability tests. The model considers the effects of cell voltage, temperature, oxygen concentration, humidity cycling, humidity level, and platinum in the membrane using inverse power law and exponential relationships within the framework of a general log-linear Weibull life-stress statistical distribution. The obtained model is capable of extrapolating the membrane lifetime from accelerated test conditions to use level conditions during field operation. Based on typical conditions for the Whistler, British Columbia fuel cell transit bus fleet, the model predicts a stack lifetime of 17,500 h and a membrane leak initiation time of 9200 h. Validation performed with the aid of a field operated stack confirmed the initial goal of the model to predict membrane lifetime within 20% of the actual operating time.

Deployment-based lifetime optimization model for homogeneous Wireless Sensor Network under retransmission.

PubMed

Li, Ruiying; Liu, Xiaoxi; Xie, Wei; Huang, Ning

2014-12-10

Sensor-deployment-based lifetime optimization is one of the most effective methods used to prolong the lifetime of Wireless Sensor Network (WSN) by reducing the distance-sensitive energy consumption. In this paper, data retransmission, a major consumption factor that is usually neglected in the previous work, is considered. For a homogeneous WSN, monitoring a circular target area with a centered base station, a sensor deployment model based on regular hexagonal grids is analyzed. To maximize the WSN lifetime, optimization models for both uniform and non-uniform deployment schemes are proposed by constraining on coverage, connectivity and success transmission rate. Based on the data transmission analysis in a data gathering cycle, the WSN lifetime in the model can be obtained through quantifying the energy consumption at each sensor location. The results of case studies show that it is meaningful to consider data retransmission in the lifetime optimization. In particular, our investigations indicate that, with the same lifetime requirement, the number of sensors needed in a non-uniform topology is much less than that in a uniform one. Finally, compared with a random scheme, simulation results further verify the advantage of our deployment model.

Crack propagation modelling for high strength steel welded structural details

NASA Astrophysics Data System (ADS)

Mecséri, B. J.; Kövesdi, B.

2017-05-01

Nowadays the barrier of applying HSS (High Strength Steel) material in bridge structures is their low fatigue strength related to yield strength. This paper focuses on the fatigue behaviour of a structural details (a gusset plate connection) made from NSS and HSS material, which is frequently used in bridges in Hungary. An experimental research program is carried out at the Budapest University of Technology and Economics to investigate the fatigue lifetime of this structural detail type through the same test specimens made from S235 and S420 steel grades. The main aim of the experimental research program is to study the differences in the crack propagation and the fatigue lifetime between normal and high strength steel structures. Based on the observed fatigue crack pattern the main direction and velocity of the crack propagation is determined. In parallel to the tests finite element model (FEM) are also developed, which model can handle the crack propagation. Using the measured strain data in the tests and the calculated values from the FE model, the approximation of the material parameters of the Paris law are calculated step-by-step, and their calculated values are evaluated. The same material properties are determined for NSS and also for HSS specimens as well, and the differences are discussed. In the current paper, the results of the experiments, the calculation method of the material parameters and the calculated values are introduced.

A portable time-domain LED fluorimeter for nanosecond fluorescence lifetime measurements

NASA Astrophysics Data System (ADS)

Wang, Hongtao; Qi, Ying; Mountziaris, T. J.; Salthouse, Christopher D.

2014-05-01

Fluorescence lifetime measurements are becoming increasingly important in chemical and biological research. Time-domain lifetime measurements offer fluorescence multiplexing and improved handling of interferers compared with the frequency-domain technique. In this paper, an all solid-state, filterless, and highly portable light-emitting-diode based time-domain fluorimeter (LED TDF) is reported for the measurement of nanosecond fluorescence lifetimes. LED based excitation provides more wavelengths options compared to laser diode based excitation, but the excitation is less effective due to the uncollimated beam, less optical power, and longer latency in state transition. Pulse triggering and pre-bias techniques were implemented in our LED TDF to improve the peak optical power to over 100 mW. The proposed pulsing circuit achieved an excitation light fall time of less than 2 ns. Electrical resetting technique realized a time-gated photo-detector to remove the interference of the excitation light with fluorescence. These techniques allow the LED fluorimeter to accurately measure the fluorescence lifetime of fluorescein down to concentration of 0.5 μM. In addition, all filters required in traditional instruments are eliminated for the non-attenuated excitation/emission light power. These achievements make the reported device attractive to biochemical laboratories seeking for highly portable lifetime detection devices for developing sensors based on fluorescence lifetime changes. The device was initially validated by measuring the lifetimes of three commercial fluorophores and comparing them with reported lifetime data. It was subsequently used to characterize a ZnSe quantum dot based DNA sensor.

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

McNeill, Jason Douglas

Electronic states of a thin layer of material on a surface possess unique physical and chemical properties. Some of these properties arise from the reduced dimensionality of the thin layer with respect to the bulk or the properties of the electric field where two materials of differing dielectric constants meet at an interface. Other properties are related to the nature of the surface chemical bond. Here, the properties of excess electrons in thin layers of Xenon, Krypton, and alkali metals are investigated, and the bound state energies and effective masses of the excess electrons are determined using two-photon photoemission. Formore » Xenon, the dependence of bound state energy, effective mass, and lifetime on layer thickness from one to nine layers is examined. Not all quantities were measured at each coverage. The two photon photoemission spectra of thin layers of Xenon on a Ag(111) substrate exhibit a number of sharp, well-defined peaks. The binding energy of the excess electronic states of Xenon layers exhibited a pronounced dependence on coverage. A discrete energy shift was observed for each additional atomic layer. At low coverage, a series of states resembling a Rydberg series is observed. This series is similar to the image state series observed on clean metal surfaces. Deviations from image state energies can be described in terms of the dielectric constant of the overlayer material and its effect on the image potential. For thicker layers of Xe (beyond the first few atomic layers), the coverage dependence of the features begins to resemble that of quantum well states. Quantum well states are related to bulk band states. However, the finite thickness of the layer restricts the perpendicular wavevector to a discrete set of values. Therefore, the spectrum of quantum well states contains a series of peaks which correspond to the various allowed values of the perpendicular wavevector. Analysis of the quantum well spectrum yields electronic band structure information. In this case, the quantum well states examined are derived from the Xenon conduction band. Measurements of the energies as a function of coverage yield the dispersion along the axis perpendicular to the surface while angle-resolved two-photon photoemission measurements yield information about dispersion along the surface parallel. The relative importance of the image potential and the overlayer band structure also depends on the quantum number and energy of the state. Some members of the image series may have an energy which is in an energy gap of the layer material, therefore such states may tend to remain physically outside the layer and retain much of their image character even at higher coverages. This is the case for the n = 1 image state of the Xe/Ag(111) system. The energies of image states which are excluded from the layer have a complex dependence on the thickness of the layer and its dielectric constant. The population decay kinetics of excited electronic states of the layer were also determined. Lifetimes are reported for the first three excited states for 1-6 atomic layers of Xe on Ag(111). As the image states evolve into quantum well states with increasing coverage, the lifetimes undergo an oscillation which marks a change in the spatial extent of the state. For example, the n = 2 quantum well state decreases substantially at 3-5 layers as the electron probability density in the layer increases. The lifetime data are modeled by extending the two-band nearly-free-electron approximation to account for the insulating Xe layer.« less

Fatigue reassessment for lifetime extension of offshore wind monopile substructures

NASA Astrophysics Data System (ADS)

Ziegler, Lisa; Muskulus, Michael

2016-09-01

Fatigue reassessment is required to decide about lifetime extension of aging offshore wind farms. This paper presents a methodology to identify important parameters to monitor during the operational phase of offshore wind turbines. An elementary effects method is applied to analyze the global sensitivity of residual fatigue lifetimes to environmental, structural and operational parameters. Therefore, renewed lifetime simulations are performed for a case study which consists of a 5 MW turbine with monopile substructure in 20 m water depth. Results show that corrosion, turbine availability, and turbulence intensity are the most influential parameters. This can vary strongly for other settings (water depth, turbine size, etc.) making case-specific assessments necessary.

Filter replacement lifetime prediction

DOEpatents

Hamann, Hendrik F.; Klein, Levente I.; Manzer, Dennis G.; Marianno, Fernando J.

2017-10-25

Methods and systems for predicting a filter lifetime include building a filter effectiveness history based on contaminant sensor information associated with a filter; determining a rate of filter consumption with a processor based on the filter effectiveness history; and determining a remaining filter lifetime based on the determined rate of filter consumption. Methods and systems for increasing filter economy include measuring contaminants in an internal and an external environment; determining a cost of a corrosion rate increase if unfiltered external air intake is increased for cooling; determining a cost of increased air pressure to filter external air; and if the cost of filtering external air exceeds the cost of the corrosion rate increase, increasing an intake of unfiltered external air.

26 CFR 1.25A-0 - Table of contents.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Credit and Lifetime Learning Credit. (1) In general. (2) Hope Scholarship Credit. (3) Lifetime Learning...) Modified adjusted gross income defined. (3) Inflation adjustment. (d) Election. (e) Identification... conviction. (2) Examples. (e) Academic period for prepayments. (1) In general. (2) Example. (f) Effective...

Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, High-Cycle and Low-Cycle Mechanical Fatigue, Creep and Thermal Fatigue Effects

NASA Technical Reports Server (NTRS)

Bast, Callie C.; Boyce, Lola

1995-01-01

The development of methodology for a probabilistic material strength degradation is described. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes five effects that typically reduce lifetime strength: high temperature, high-cycle mechanical fatigue, low-cycle mechanical fatigue, creep and thermal fatigue. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing predictions of high-cycle mechanical fatigue and high temperature effects with experiments are presented. Results from this limited verification study strongly supported that material degradation can be represented by randomized multifactor interaction models.

Cost-effectiveness of one-time genetic testing to minimize lifetime adverse drug reactions.

PubMed

Alagoz, O; Durham, D; Kasirajan, K

2016-04-01

We evaluated the cost-effectiveness of one-time pharmacogenomic testing for preventing adverse drug reactions (ADRs) over a patient's lifetime. We developed a Markov-based Monte Carlo microsimulation model to represent the ADR events in the lifetime of each patient. The base-case considered a 40-year-old patient. We measured health outcomes in life years (LYs) and quality-adjusted LYs (QALYs) and estimated costs using 2013 US$. In the base-case, one-time genetic testing had an incremental cost-effectiveness ratio (ICER) of $43,165 (95% confidence interval (CI) is ($42,769,$43,561)) per additional LY and $53,680 per additional QALY (95% CI is ($53,182,$54,179)), hence under the base-case one-time genetic testing is cost-effective. The ICER values were most sensitive to the average probability of death due to ADR, reduction in ADR rate due to genetic testing, mean ADR rate and cost of genetic testing.

Effect of coulomb correlations on luminescence and absorption in compensated semiconductors

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

Bogoslovskiy, N. A., E-mail: nikitabogoslovskiy@gmail.com; Petrov, P. V.; Ivánov, Yu. L.

2016-07-15

The spectra of donor–acceptor light absorption and luminescence in lightly doped and lightly compensated semiconductors are calculated. In the photoluminescence calculation, two limiting cases of long and short carrier lifetimes relative to the carrier-energy relaxation time are considered. It is shown that, at long lifetimes, the photoluminescence spectrum is significantly shifted toward longer wavelengths due to the relaxation of minority charge carriers. At intermediate lifetimes, the photoluminescence spectrum consists of two peaks, which is in good agreement with the experimental data.

Cost-effectiveness of an HPV self-collection campaign in Uganda: comparing models for delivery of cervical cancer screening in a low-income setting

PubMed Central

Campos, Nicole G; Tsu, Vivien; Jeronimo, Jose; Njama-Meya, Denise; Mvundura, Mercy; Kim, Jane J

2017-01-01

Abstract With the availability of a low-cost HPV DNA test that can be administered by either a healthcare provider or a woman herself, programme planners require information on the costs and cost-effectiveness of implementing cervical cancer screening programmes in low-resource settings under different models of healthcare delivery. Using data from the START-UP demonstration project and a micro-costing approach, we estimated the health and economic impact of once-in-a-lifetime HPV self-collection campaign relative to clinic-based provider-collection of HPV specimens in Uganda. We used an individual-based Monte Carlo simulation model of the natural history of HPV and cervical cancer to estimate lifetime health and economic outcomes associated with screening with HPV DNA testing once in a lifetime (clinic-based provider-collection vs a self-collection campaign). Test performance and cost data were obtained from the START-UP demonstration project using a micro-costing approach. Model outcomes included lifetime risk of cervical cancer, total lifetime costs (in 2011 international dollars [I$]), and life expectancy. Cost-effectiveness ratios were expressed using incremental cost-effectiveness ratios (ICERs). When both strategies achieved 75% population coverage, ICERs were below Uganda’s per capita GDP (self-collection: I$80 per year of life saved [YLS]; provider-collection: I$120 per YLS). When the self-collection campaign achieved coverage gains of 15–20%, it was more effective than provider-collection, and had a lower ICER unless coverage with both strategies was 50% or less. Findings were sensitive to cryotherapy compliance among screen-positive women and relative HPV test performance. The primary limitation of this analysis is that self-collection costs are based on a hypothetical campaign but are based on unit costs from Uganda. Once-in-a-lifetime screening with HPV self-collection may be very cost-effective and reduce cervical cancer risk by > 20% if coverage is high. Demonstration projects will be needed to confirm the validity of our logistical, costing and compliance assumptions. PMID:28369405

Cost-effectiveness of an HPV self-collection campaign in Uganda: comparing models for delivery of cervical cancer screening in a low-income setting.

PubMed

Campos, Nicole G; Tsu, Vivien; Jeronimo, Jose; Njama-Meya, Denise; Mvundura, Mercy; Kim, Jane J

2017-09-01

With the availability of a low-cost HPV DNA test that can be administered by either a healthcare provider or a woman herself, programme planners require information on the costs and cost-effectiveness of implementing cervical cancer screening programmes in low-resource settings under different models of healthcare delivery. Using data from the START-UP demonstration project and a micro-costing approach, we estimated the health and economic impact of once-in-a-lifetime HPV self-collection campaign relative to clinic-based provider-collection of HPV specimens in Uganda. We used an individual-based Monte Carlo simulation model of the natural history of HPV and cervical cancer to estimate lifetime health and economic outcomes associated with screening with HPV DNA testing once in a lifetime (clinic-based provider-collection vs a self-collection campaign). Test performance and cost data were obtained from the START-UP demonstration project using a micro-costing approach. Model outcomes included lifetime risk of cervical cancer, total lifetime costs (in 2011 international dollars [I$]), and life expectancy. Cost-effectiveness ratios were expressed using incremental cost-effectiveness ratios (ICERs). When both strategies achieved 75% population coverage, ICERs were below Uganda's per capita GDP (self-collection: I$80 per year of life saved [YLS]; provider-collection: I$120 per YLS). When the self-collection campaign achieved coverage gains of 15-20%, it was more effective than provider-collection, and had a lower ICER unless coverage with both strategies was 50% or less. Findings were sensitive to cryotherapy compliance among screen-positive women and relative HPV test performance. The primary limitation of this analysis is that self-collection costs are based on a hypothetical campaign but are based on unit costs from Uganda. Once-in-a-lifetime screening with HPV self-collection may be very cost-effective and reduce cervical cancer risk by > 20% if coverage is high. Demonstration projects will be needed to confirm the validity of our logistical, costing and compliance assumptions. © The Author 2017. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine.

Stability and Metastability of Trapless Bose-Einstein Condensates and Quantum Liquids

NASA Astrophysics Data System (ADS)

Zloshchastiev, Konstantin G.

2017-07-01

Various kinds of Bose-Einstein condensates are considered, which evolve without any geometric constraints or external trap potentials including gravitational. For studies of their collective oscillations and stability, including the metastability and macroscopic tunneling phenomena, both the variational approach and the Vakhitov-Kolokolov (VK) criterion are employed; calculations are done for condensates of an arbitrary spatial dimension. It is determined that that the trapless condensate described by the logarithmic wave equation is essentially stable, regardless of its dimensionality, while the trapless condensates described by wave equations of a polynomial type with respect to the wavefunction, such as the Gross-Pitaevskii (cubic), cubic-quintic, and so on, are at best metastable. This means that trapless "polynomial" condensates are unstable against spontaneous delocalization caused by fluctuations of their width, density and energy, leading to a finite lifetime.

Embedded scattering eigenstates using resonant metasurfaces

NASA Astrophysics Data System (ADS)

Krasnok, Alex; Alú, Andrea

2018-06-01

Optical embedded eigenstates (EEs) are localized modes of an open structure that are compatible to radiation, yet they have infinite lifetime and diverging quality factors. Their realization in nanostructures finite in all dimensions is inherently challenging, because they require materials with extreme electromagnetic properties. Here we explore the realization of these bound states in the continuum using ultrathin metasurfaces composed of arrays of nanoparticles. We first show that arrays of lossless nanoparticles can realize the condition for EEs, and then explore the use of Ag nanoparticles coated with gain media shells to compensate material loss and revive the EE despite realistic loss in plasmonic materials. We discuss the possible experimental realization of the proposed structures, and provide useful guidelines for practical implementation in nanophotonics systems with largely enhanced light–matter interactions. These metasurfaces may lead to highly efficient lasers, filters, frequency comb generation and sensors.

Advances and trends in structural and solid mechanics; Proceedings of the Symposium, Washington, DC, October 4-7, 1982

NASA Technical Reports Server (NTRS)

Noor, A. K. (Editor); Housner, J. M.

1983-01-01

The mechanics of materials and material characterization are considered, taking into account micromechanics, the behavior of steel structures at elevated temperatures, and an anisotropic plasticity model for inelastic multiaxial cyclic deformation. Other topics explored are related to advances and trends in finite element technology, classical analytical techniques and their computer implementation, interactive computing and computational strategies for nonlinear problems, advances and trends in numerical analysis, database management systems and CAD/CAM, space structures and vehicle crashworthiness, beams, plates and fibrous composite structures, design-oriented analysis, artificial intelligence and optimization, contact problems, random waves, and lifetime prediction. Earthquake-resistant structures and other advanced structural applications are also discussed, giving attention to cumulative damage in steel structures subjected to earthquake ground motions, and a mixed domain analysis of nuclear containment structures using impulse functions.

Disposal of hypergolic propellants, phase 6 task 4. Disposal pond products

NASA Technical Reports Server (NTRS)

Cohenour, B. C.; Wiederhold, C. N.

1977-01-01

Waste monomethyl hydrazine scrubber liquor, consisting of aqueous solutions containing small amounts of CH4, Cl2, CH3Cl, CH2Cl2, and CHCl3 as well as large amounts of CH3OH is scheduled to be dumped in stabilization ponds along with nitrate and nitrite salt solutions obtained as waste liquors from the N2O4 scrubbers. The wastes are investigated as to the hazardous materials generated by such combinations of items as described as well as the finite lifetime of such materials in the stabilization ponds. The gas liquid chromatograph was used in the investigation. A series of experiments designed to convert nitrate and nitrite salts to the environmentally innocuous N2O and N2 using solar energy is reported. Results indicate that this solar conversion is feasible.

Effects of Communities That Care on Males' and Females' Drug Use and Delinquency 9 Years After Baseline in a Community-Randomized Trial.

PubMed

Oesterle, Sabrina; Hawkins, J David; Kuklinski, Margaret R; Fagan, Abigail A; Fleming, Christopher; Rhew, Isaac C; Brown, Eric C; Abbott, Robert D; Catalano, Richard F

2015-12-01

This study tested sustained effects of the Communities That Care (CTC) prevention system on health-risking behaviors 9 years after baseline in a community-randomized trial involving 24 towns in seven states. Earlier analyses found sustained effects on abstinence from drug use and delinquency through Grade 12 in a panel of fifth graders. At age 19, 91 % (n = 3986) of the living panel completed the survey. Data were analyzed using generalized linear mixed models. The prevalence of lifetime and current substance use and delinquency were the primary outcomes. Secondary outcomes included substance use disorders, major depression, suicidality, educational attainment, and sexual risk behaviors. CTC had a significant overall effect across lifetime measures of the primary outcomes for males, but not for females or the full sample, although lifetime abstinence from delinquency in the full sample was significantly higher in CTC communities (ARR = 1.16). Males in CTC communities also continued to show greater lifetime abstinence from cigarette smoking (ARR = 1.22). CTC did not have a sustained effect on current substance use and delinquency nor did it improve the secondary outcomes at age 19 for either gender. Communities using CTC may need to extend their prevention planning to include the high school years to sustain effects on drug use and delinquency beyond high school for both genders. ClinicalTrials.gov identifier: NCT01088542.

Effects of Communities That Care on Males’ and Females’ Drug Use and Delinquency 9 Years After Baseline in a Community-Randomized Trial

PubMed Central

Hawkins, J. David; Kuklinski, Margaret R.; Fagan, Abigail A.; Fleming, Christopher; Rhew, Isaac C.; Brown, Eric C.; Abbott, Robert D.; Catalano, Richard F.

2016-01-01

This study tested sustained effects of the Communities That Care (CTC) prevention system on health-risking behaviors 9 years after baseline in a community-randomized trial involving 24 towns in seven states. Earlier analyses found sustained effects on abstinence from drug use and delinquency through Grade 12 in a panel of fifth graders. At age 19, 91 % (n = 3986) of the living panel completed the survey. Data were analyzed using generalized linear mixed models. The prevalence of lifetime and current substance use and delinquency were the primary outcomes. Secondary outcomes included substance use disorders, major depression, suicidality, educational attainment, and sexual risk behaviors. CTC had a significant overall effect across lifetime measures of the primary outcomes for males, but not for females or the full sample, although lifetime abstinence from delinquency in the full sample was significantly higher in CTC communities (ARR = 1.16). Males in CTC communities also continued to show greater lifetime abstinence from cigarette smoking (ARR = 1.22). CTC did not have a sustained effect on current substance use and delinquency nor did it improve the secondary outcomes at age 19 for either gender. Communities using CTC may need to extend their prevention planning to include the high school years to sustain effects on drug use and delinquency beyond high school for both genders. PMID:26377418

Results and Systematic Studies of the UCN Lifetime Experiment at NIST

NASA Astrophysics Data System (ADS)

Huffer, Craig Reeves

The neutron beta-decay lifetime is important in understanding weak interactions in the framework of the Standard Model, and it is an input to nuclear astrophysics and Big Bang Nucleosynthesis. Current measurements of the neutron beta-decay lifetime disagree, which has motivated additional experiments that are sensitive to different sets of systematic effects. An effort continues at the NIST Center for Neutron Research (NCNR) to improve the statistical and systematic limitations of an experiment to measure the neutron beta-decay lifetime using magnetically trapped UCN. In the experiment, a monoenergetic 0:89 nm cold neutron is incident on a superfluid 4He target within the minimum field region of an Ioffe type magnetic trap. Some of the neutrons are subsequently downscattered by single phonons in the helium to low energies (≈ 200 neV), and those in the appropriate spin state become trapped. The inverse process, upscattering of UCN, is suppressed by the low phonon density in the < 300 mK helium. When the neutron decays, the energetic electron creates EUV scintillation light, which is down-converted and transported out of the cell to PMTs operated at room temperature. With this method, the decay of the UCN population can be monitored in situ. The apparatus, analysis, data, and systematics will be discussed. After accounting for the systematic effects the measured lifetime disagrees with the current PDG mean neutron beta-decay lifetime by about 9 of our standard deviations, which is a strong indication of unaccounted for systematic effects. Additional 3He contamination will be shown to be the most likely candidate for the additional systematic shift, which motivated the commissioning and initial operation of a heat flush purifier for purifying additional 4He. This work ends with a description of the 4He purifier and its performance.

Recombination activity associated with thermal donor generation in monocrystalline silicon and effect on the conversion efficiency of heterojunction solar cells

NASA Astrophysics Data System (ADS)

Tomassini, M.; Veirman, J.; Varache, R.; Letty, E.; Dubois, S.; Hu, Y.; Nielsen, Ø.

2016-02-01

The recombination properties of the carrier lifetime-limiting center formed during the generation of oxygen-related thermal donors (so called "old" thermal donors) in n-type Czochralski silicon were determined over a wide range of thermal donors' concentrations. The procedure involved (1) determining the various energy levels associated with dopants with the help of temperature Hall effect measurements, (2) clarifying which energy level limits the carrier lifetime by temperature lifetime spectroscopy, and (3) determining the recombination parameters of the involved defect from room-temperature carrier lifetime curves. Our results support the fact that a deep energy level in the range of 0.2-0.3 eV below the conduction band limits the carrier lifetime. The second family of thermal donors, featuring bistable properties, was tentatively identified as the corresponding defect. From the obtained experimental data, the influence of the defect on the amorphous/crystalline silicon heterojunction solar cell conversion efficiency was simulated. It is observed that for extended donor generation, the carrier lifetime is reduced by orders-of-magnitude, leading to unacceptable losses in photovoltaic conversion efficiency. A key result is that even for samples with thermal donor concentrations of 1015 cm-3—often met in seed portions of commercial ingots—simulations reveal efficiency losses greater than 1% absolute for state-of-the-art cells, in agreement with recent experimental studies from our group. This result indicates to crystal growers the importance to mitigate the formation of thermal donors or to develop cost-effective processes to suppress them at the ingot/wafer scale. This is even more critical as ingot cool-down is likely to be slower for future larger ingots, thus promoting the formation of thermal donors.

Vector two-point functions in finite volume using partially quenched chiral perturbation theory at two loops

NASA Astrophysics Data System (ADS)

Bijnens, Johan; Relefors, Johan

2017-12-01

We calculate vector-vector correlation functions at two loops using partially quenched chiral perturbation theory including finite volume effects and twisted boundary conditions. We present expressions for the flavor neutral cases and the flavor charged case with equal masses. Using these expressions we give an estimate for the ratio of disconnected to connected contributions for the strange part of the electromagnetic current. We give numerical examples for the effects of partial quenching, finite volume and twisting and suggest the use of different twists to check the size of finite volume effects. The main use of this work is expected to be for lattice QCD calculations of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment.

Inferring probabilistic stellar rotation periods using Gaussian processes

NASA Astrophysics Data System (ADS)

Angus, Ruth; Morton, Timothy; Aigrain, Suzanne; Foreman-Mackey, Daniel; Rajpaul, Vinesh

2018-02-01

Variability in the light curves of spotted, rotating stars is often non-sinusoidal and quasi-periodic - spots move on the stellar surface and have finite lifetimes, causing stellar flux variations to slowly shift in phase. A strictly periodic sinusoid therefore cannot accurately model a rotationally modulated stellar light curve. Physical models of stellar surfaces have many drawbacks preventing effective inference, such as highly degenerate or high-dimensional parameter spaces. In this work, we test an appropriate effective model: a Gaussian Process with a quasi-periodic covariance kernel function. This highly flexible model allows sampling of the posterior probability density function of the periodic parameter, marginalizing over the other kernel hyperparameters using a Markov Chain Monte Carlo approach. To test the effectiveness of this method, we infer rotation periods from 333 simulated stellar light curves, demonstrating that the Gaussian process method produces periods that are more accurate than both a sine-fitting periodogram and an autocorrelation function method. We also demonstrate that it works well on real data, by inferring rotation periods for 275 Kepler stars with previously measured periods. We provide a table of rotation periods for these and many more, altogether 1102 Kepler objects of interest, and their posterior probability density function samples. Because this method delivers posterior probability density functions, it will enable hierarchical studies involving stellar rotation, particularly those involving population modelling, such as inferring stellar ages, obliquities in exoplanet systems, or characterizing star-planet interactions. The code used to implement this method is available online.

The finite ground plane effect on the microstrip antenna radiation patterns

NASA Technical Reports Server (NTRS)

Huang, J.

1983-01-01

The uniform geometrical theory of diffraction (GTD) is employed for calculating the edge diffracted fields from the finite ground plane of a microstrip antenna. The source field from the radiating patch is calculated by two different methods: the slot theory and the modal expansion theory. Many numerical and measured results are presented to demonstrate the accuracy of the calculations and the finite ground plane edge effect.

Discontinuous Observers Design for Finite-Time Consensus of Multiagent Systems With External Disturbances.

PubMed

Liu, Xiaoyang; Ho, Daniel W C; Cao, Jinde; Xu, Wenying

This brief investigates the problem of finite-time robust consensus (FTRC) for second-order nonlinear multiagent systems with external disturbances. Based on the global finite-time stability theory of discontinuous homogeneous systems, a novel finite-time convergent discontinuous disturbed observer (DDO) is proposed for the leader-following multiagent systems. The states of the designed DDO are then used to design the control inputs to achieve the FTRC of nonlinear multiagent systems in the presence of bounded disturbances. The simulation results are provided to validate the effectiveness of these theoretical results.This brief investigates the problem of finite-time robust consensus (FTRC) for second-order nonlinear multiagent systems with external disturbances. Based on the global finite-time stability theory of discontinuous homogeneous systems, a novel finite-time convergent discontinuous disturbed observer (DDO) is proposed for the leader-following multiagent systems. The states of the designed DDO are then used to design the control inputs to achieve the FTRC of nonlinear multiagent systems in the presence of bounded disturbances. The simulation results are provided to validate the effectiveness of these theoretical results.

Observer-based robust finite time H∞ sliding mode control for Markovian switching systems with mode-dependent time-varying delay and incomplete transition rate.

PubMed

Gao, Lijun; Jiang, Xiaoxiao; Wang, Dandan

2016-03-01

This paper investigates the problem of robust finite time H∞ sliding mode control for a class of Markovian switching systems. The system is subjected to the mode-dependent time-varying delay, partly unknown transition rate and unmeasurable state. The main difficulty is that, a sliding mode surface cannot be designed based on the unknown transition rate and unmeasurable state directly. To overcome this obstacle, the set of modes is firstly divided into two subsets standing for known transition rate subset and unknown one, based on which a state observer is established. A component robust finite-time sliding mode controller is also designed to cope with the effect of partially unknown transition rate. It is illustrated that the reachability, finite-time stability, finite-time boundedness, finite-time H∞ state feedback stabilization of sliding mode dynamics can be ensured despite the unknown transition rate. Finally, the simulation results verify the effectiveness of robust finite time control problem. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Lifetime moderate-to-vigorous physical activity and ER/PR/HER-defined post-menopausal breast cancer risk.

PubMed

Shi, Joy; Kobayashi, Lindsay C; Grundy, Anne; Richardson, Harriet; SenGupta, Sandip K; Lohrisch, Caroline A; Spinelli, John J; Aronson, Kristan J

2017-08-01

To assess the relationship of moderate-to-vigorous physical activity (MVPA) in leisure-time, household, and occupational domains across the total lifetime and in four age periods with breast cancer risk, as defined by estrogen receptor (ER)/progesterone receptor (PR) status and ER/PR/human epidermal growth factor-2 (HER2) status, among post-menopausal women. Data were from 692 women with incident breast cancer and 644 controls in the Canadian Breast Cancer Study, a case-control study of women aged 40-80 years in British Columbia and Ontario. Mean metabolic equivalent (MET)-hours/week for questionnaire-assessed leisure-time, household, and occupational MVPA were calculated for the total lifetime and four age periods (12-17, 18-34, 45-49, and ≥50 years). Odds ratios (ORs) for the relationships between domain-specific MVPA at each lifetime period and risks of ER/PR-defined and ER/PR/HER2-defined breast cancers were estimated using polytomous logistic regression. Trend tests for dose-response relationships were calculated for the ORs across increasing tertiles of mean MET-hours/week of MVPA. Total lifetime leisure-time MVPA was associated with reduced risk of ER-/PR- breast cancer in a dose-response fashion (p trend  = 0.014). In contrast, total lifetime household MVPA was associated with reduced risk of ER+ and/or PR+ breast cancer (p trend  < 0.001). When further stratified by HER2 status, the effect of leisure-time MVPA appeared confined to HER2- breast cancers, and the effect of household MVPA did not differ according to HER2 status. Similar trends were observed when stratified by age period. Lifetime leisure-time MVPA appeared to be associated with reduced risk of ER-/PR-/HER2- breast cancers and lifetime household MVPA was associated with reduced risk of ER+ and/or PR+ breast cancer, regardless of HER2 status.

The role of driver rehabilitation in extending the driving lifetimes and enhancing the mobility of older adults.

DOT National Transportation Integrated Search

2013-06-01

This study explored the role and impact of driver rehabilitation for older adults on extending : driving lifetimes and enhancing mobility. Specifically, the focus was on the effects of driver : rehabilitation on older adults abilities to continue ...

High-frequency sum rules for classical one-component plasma in a magnetic field

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

Genga, R.O.

A high-frequency sum-rule expansion is derived for all elements of a classical plasma dielectric tensor in the presence of an external magnetic field. Omega/sub 4//sup 13/ is found to be the only coefficient of omega/sup -4/ that has no correlational and finite-radiation-temperature contributions. The finite-radiation-temperature effect results in an upward renormalization of the frequencies of the modes; it also leads to either reduction of the negative correlational effect on the positive thermal dispersion or, together with correlation, enhancement of the positive thermal dispersion for finite k, depending on the direction of propagation. Further, for the extraordinary mode, the finite-radiation-temperature effectmore » increases the positive refractive dispersion for finite k.« less

Finite-time robust passive control for a class of switched reaction-diffusion stochastic complex dynamical networks with coupling delays and impulsive control

NASA Astrophysics Data System (ADS)

Syed Ali, M.; Yogambigai, J.; Kwon, O. M.

2018-03-01

Finite-time boundedness and finite-time passivity for a class of switched stochastic complex dynamical networks (CDNs) with coupling delays, parameter uncertainties, reaction-diffusion term and impulsive control are studied. Novel finite-time synchronisation criteria are derived based on passivity theory. This paper proposes a CDN consisting of N linearly and diffusively coupled identical reaction- diffusion neural networks. By constructing of a suitable Lyapunov-Krasovskii's functional and utilisation of Jensen's inequality and Wirtinger's inequality, new finite-time passivity criteria for the networks are established in terms of linear matrix inequalities (LMIs), which can be checked numerically using the effective LMI toolbox in MATLAB. Finally, two interesting numerical examples are given to show the effectiveness of the theoretical results.

Differential Susceptibility: The Genetic Moderation of Peer Pressure on Alcohol Use

PubMed Central

Cleveland, H. Harrington; Schlomer, Gabriel L.; Vandenbergh, David J.; Feinberg, Mark E.

2016-01-01

Although peer pressure can influence adolescents’ alcohol use, individual susceptibility to these pressures varies across individuals. The dopamine receptor D4 gene (DRD4) is a potential candidate gene that may influence adolescents’ susceptibility to their peer environment due to the role dopamine plays in reward sensation during social interaction. We hypothesized that DRD4 genotype status would moderate the impact of 7th-grade antisocial peer pressure on 12th-grade lifetime alcohol use (n = 414; 58.7 % female; 92.8 % White). The results revealed significant main effects for antisocial peer pressure, but no main effects for DRD4 genotype on lifetime alcohol use. Adolescent DRD4 genotype moderated the association between peer pressure and lifetime alcohol use. For individuals who carried at least one copy of the DRD4 7-repeat allele (7+), antisocial peer pressure was associated with increased lifetime alcohol use. These findings indicate that genetic sensitivity to peer pressure confers increased alcohol use in late adolescence. PMID:26307243

Differential Susceptibility: The Genetic Moderation of Peer Pressure on Alcohol Use.

PubMed

Griffin, Amanda M; Cleveland, H Harrington; Schlomer, Gabriel L; Vandenbergh, David J; Feinberg, Mark E

2015-10-01

Although peer pressure can influence adolescents' alcohol use, individual susceptibility to these pressures varies across individuals. The dopamine receptor D4 gene (DRD4) is a potential candidate gene that may influence adolescents' susceptibility to their peer environment due to the role dopamine plays in reward sensation during social interaction. We hypothesized that DRD4 genotype status would moderate the impact of 7th-grade antisocial peer pressure on 12th-grade lifetime alcohol use (n = 414; 58.7% female; 92.8% White). The results revealed significant main effects for antisocial peer pressure, but no main effects for DRD4 genotype on lifetime alcohol use. Adolescent DRD4 genotype moderated the association between peer pressure and lifetime alcohol use. For individuals who carried at least one copy of the DRD4 7-repeat allele (7+), antisocial peer pressure was associated with increased lifetime alcohol use. These findings indicate that genetic sensitivity to peer pressure confers increased alcohol use in late adolescence.

Methodological considerations for global analysis of cellular FLIM/FRET measurements

NASA Astrophysics Data System (ADS)

Adbul Rahim, Nur Aida; Pelet, Serge; Kamm, Roger D.; So, Peter T. C.

2012-02-01

Global algorithms can improve the analysis of fluorescence energy transfer (FRET) measurement based on fluorescence lifetime microscopy. However, global analysis of FRET data is also susceptible to experimental artifacts. This work examines several common artifacts and suggests remedial experimental protocols. Specifically, we examined the accuracy of different methods for instrument response extraction and propose an adaptive method based on the mean lifetime of fluorescent proteins. We further examined the effects of image segmentation and a priori constraints on the accuracy of lifetime extraction. Methods to test the applicability of global analysis on cellular data are proposed and demonstrated. The accuracy of global fitting degrades with lower photon count. By systematically tracking the effect of the minimum photon count on lifetime and FRET prefactors when carrying out global analysis, we demonstrate a correction procedure to recover the correct FRET parameters, allowing us to obtain protein interaction information even in dim cellular regions with photon counts as low as 100 per decay curve.

The cost-effectiveness of telestroke in the treatment of acute ischemic stroke

PubMed Central

Nelson, R.E.; Saltzman, G.M.; Skalabrin, E.J.; Demaerschalk, B.M.

2011-01-01

Objective: To conduct a cost-effectiveness analysis of telestroke—a 2-way, audiovisual technology that links stroke specialists to remote emergency department physicians and their stroke patients—compared to usual care (i.e., remote emergency departments without telestroke consultation or stroke experts). Methods: A decision-analytic model was developed for both 90-day and lifetime horizons. Model inputs were taken from published literature where available and supplemented with western states' telestroke experiences. Costs were gathered using a societal perspective and converted to 2008 US dollars. Quality-adjusted life-years (QALYs) gained were combined with costs to generate incremental cost-effectiveness ratios (ICERs). In the lifetime horizon model, both costs and QALYs were discounted at 3% annually. Both one-way sensitivity analyses and Monte Carlo simulations were performed. Results: In the base case analysis, compared to usual care, telestroke results in an ICER of $108,363/QALY in the 90-day horizon and $2,449/QALY in the lifetime horizon. For the 90-day and lifetime horizons, 37.5% and 99.7% of 10,000 Monte Carlo simulations yielded ICERs <$50,000/QALY, a ratio commonly considered acceptable in the United States. Conclusion: When a lifetime perspective is taken, telestroke appears cost-effective compared to usual care, since telestroke costs are upfront but benefits of improved stroke care are lifelong. If barriers to use such as low reimbursement rates and high equipment costs are reduced, telestroke has the potential to diminish the striking geographic disparities of acute stroke care in the United States. PMID:21917781

Effect of pharmacologically induced retinal degeneration on retinal autofluorescence lifetimes in mice.

PubMed

Dysli, Chantal; Dysli, Muriel; Zinkernagel, Martin S; Enzmann, Volker

2016-12-01

Fluorescence lifetime imaging ophthalmoscopy (FLIO) was used to investigate retinal autofluorescence lifetimes in mouse models of pharmacologically induced retinal degeneration over time. Sodium iodate (NaIO 3 , 35 mg/kg intravenously) was used to induce retinal pigment epithelium (RPE) degeneration with subsequent loss of photoreceptors (PR) whereas N-methyl-N-nitrosourea (MNU, 45 mg/kg intraperitoneally) was employed for degeneration of the photoreceptor cell layer alone. All mice were measured at day 3, 7, 14, and 28 after the respective injection of NaIO 3 , MNU or NaCl (control). Fluorescence lifetime imaging was performed using a fluorescence lifetime imaging ophthalmoscope (Heidelberg Engineering, Heidelberg, Germany). Fluorescence was excited at 473 nm and fluorescence lifetimes were measured in a short and a long spectral channel (498-560 nm and 560-720 nm). Corresponding optical coherence tomography (OCT) images were consecutively acquired and histology was performed at the end of the experiments. Segmentation of OCT images and histology verified the cell type-specific degeneration process over time. Retinal autofluorescence lifetimes increased from day 3 to day 28 in mice after NaIO 3 treatment. Finally, at day 28, fluorescence lifetimes were prolonged by 8% in the short and 61% in the long spectral channel compared to control animals (p = 0.21 and p = 0.004, respectively). In mice after MNU treatment, the mean retinal autofluorescence lifetimes were already decreased at day 3 and retinal lifetimes were finally shortened by 27% in the short and 51% in the long spectral channel at day 28 (p = 0.0028). In conclusion, degeneration of the RPE with subsequent photoreceptor degeneration by NaIO 3 lead to longer mean fluorescence lifetimes of the retina compared to control mice, whereas during specific degeneration of the photoreceptor layer induced by MNU shorter lifetimes were measured. Therefore, short retinal fluorescence lifetimes may originate from the RPE and may be modified by the overlaying retinal layers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimating finite-population reproductive numbers in heterogeneous populations.

PubMed

Keegan, Lindsay T; Dushoff, Jonathan

2016-05-21

The basic reproductive number, R0, is one of the most important epidemiological quantities. R0 provides a threshold for elimination and determines when a disease can spread or when a disease will die out. Classically, R0 is calculated assuming an infinite population of identical hosts. Previous work has shown that heterogeneity in the host mixing rate increases R0 in an infinite population. However, it has been suggested that in a finite population, heterogeneity in the mixing rate may actually decrease the finite-population reproductive numbers. Here, we outline a framework for discussing different types of heterogeneity in disease parameters, and how these affect disease spread and control. We calculate "finite-population reproductive numbers" with different types of heterogeneity, and show that in a finite population, heterogeneity has complicated effects on the reproductive number. We find that simple heterogeneity decreases the finite-population reproductive number, whereas heterogeneity in the intrinsic mixing rate (which affects both infectiousness and susceptibility) increases the finite-population reproductive number when R0 is small relative to the size of the population and decreases the finite-population reproductive number when R0 is large relative to the size of the population. Although heterogeneity has complicated effects on the finite-population reproductive numbers, its implications for control are straightforward: when R0 is large relative to the size of the population, heterogeneity decreases the finite-population reproductive numbers, making disease control or elimination easier than predicted by R0. Copyright © 2016 Elsevier Ltd. All rights reserved.

Heritability of lifetime ecstasy use.

PubMed

Verweij, Karin J H; Treur, Jorien L; Vreeker, Annabel; Brunt, Tibor M; Willemsen, Gonneke; Boomsma, Dorret I; Vink, Jacqueline M

2017-09-01

Ecstasy is a widely used psychoactive drug that users often take because they experience positive effects such as increased euphoria, sociability, elevated mood, and heightened sensations. Ecstasy use is not harmless and several immediate and long term side effects have been identified. Lifetime ecstasy use is likely to be partly influenced by genetic factors, but no twin study has determined the heritability. Here, we apply a classical twin design to a large sample of twins and siblings to estimate the heritability of lifetime ecstasy use. The sample comprised 8500 twins and siblings aged between 18 and 45 years from 5402 families registered at the Netherlands Twin Registry. In 2013-2014 participants filled out a questionnaire including a question whether they had ever used ecstasy. We used the classical twin design to partition the individual differences in liability to ecstasy use into that due to genetic, shared environmental, and residual components. Overall, 10.4% of the sample had used ecstasy during their lifetime, with a somewhat higher prevalence in males than females. Twin modelling indicated that individual differences in liability to lifetime ecstasy use are for 74% due to genetic differences between individuals, whereas shared environmental and residual factors explain a small proportion of its liability (5% and 21%, respectively). Although heritability estimates appeared to be higher for females than males, this difference was not significant. Lifetime ecstasy use is a highly heritable trait, which indicates that some people are genetically more vulnerable to start using ecstasy than others. Copyright © 2017. Published by Elsevier B.V.

Accounting for measurement error in human life history trade-offs using structural equation modeling.

PubMed

Helle, Samuli

2018-03-01

Revealing causal effects from correlative data is very challenging and a contemporary problem in human life history research owing to the lack of experimental approach. Problems with causal inference arising from measurement error in independent variables, whether related either to inaccurate measurement technique or validity of measurements, seem not well-known in this field. The aim of this study is to show how structural equation modeling (SEM) with latent variables can be applied to account for measurement error in independent variables when the researcher has recorded several indicators of a hypothesized latent construct. As a simple example of this approach, measurement error in lifetime allocation of resources to reproduction in Finnish preindustrial women is modelled in the context of the survival cost of reproduction. In humans, lifetime energetic resources allocated in reproduction are almost impossible to quantify with precision and, thus, typically used measures of lifetime reproductive effort (e.g., lifetime reproductive success and parity) are likely to be plagued by measurement error. These results are contrasted with those obtained from a traditional regression approach where the single best proxy of lifetime reproductive effort available in the data is used for inference. As expected, the inability to account for measurement error in women's lifetime reproductive effort resulted in the underestimation of its underlying effect size on post-reproductive survival. This article emphasizes the advantages that the SEM framework can provide in handling measurement error via multiple-indicator latent variables in human life history studies. © 2017 Wiley Periodicals, Inc.

Associations between strain, herd size, age at first calving, culling reason and lifetime performance characteristics in Holstein-Friesian cows.

PubMed

Adamczyk, K; Makulska, J; Jagusiak, W; Węglarz, A

2017-02-01

Cow longevity and lifetime performance traits are good indicators of breeding effectiveness and animal welfare. They are also interrelated with the economics of dairy herd. Unfortunately, a high milk yield is often associated with deteriorated cow health and fertility and, consequently, with an increased culling rate. This situation, observed also in the Polish population of Holstein-Friesian cattle, inspired us to undertake a study on the associations between some factors and lifetime performance characteristics. The data set consisted of the records on 135 496 cows, including 131 526 of the Black and White strain (BW), and 3970 of the Red and White strain (RW) covered by performance recording and culled in 2012. It was found that cows of the BW strain and those from the largest herds (>100 cows) reached higher lifetime and mean daily energy-corrected milk (ECM) yields than cows of the RW strain and those from smaller herds culled at a similar age. Cows youngest at first calving (<2.0 years) were characterised by the highest lifetime ECM yield. It indicates that heifers can be bred even when they are younger than 15 to 16 months with no significant negative effect on their later performance. Infertility and reproduction problems (39.6%) and udder diseases (15.5%) constituted the most frequent reasons for cow culling. Cow longevity and lifetime productivity were considerably affected by the interactions between the studied factors.

Perimeter Governed Minority Carrier Lifetimes in 4H-SiC p(+)-n Diodes Measured by Reverse Recovery Switching Transient Analysis

NASA Technical Reports Server (NTRS)

Neudeck, Philip G.

1998-01-01

Minority carrier lifetimes in epitaxial 4H-SiC p(+)-n junction diodes were measured via an analysis of reverse recovery switching characteristics. Behavior of reverse recovery storage time (t(s)) as a function of initial ON-state forward current (I(F)) and OFF-state reverse current (I(R)) followed well-documented trends which have been observed for decades in silicon p-n rectifiers. Average minority carrier (hole) lifetimes (tau(p)) calculated from plots of t(s) vs I(R)/I(F) strongly decreased with decreasing device area. Bulk and perimeter components of average hole lifetimes were separated by plotting 1/tau(p) as a function of device perimeter-to- area ratio (P/A). This plot reveals that perimeter recombination is dominant in these devices, whose areas are all less than 1 sq mm. The bulk minority carrier (hole) lifetime extracted from the 1/tau(p) vs P/A plot is approximately 0.7 micro-s, well above the 60 ns to 300 ns average iit'eptimes obtained when perimeter recombination effects are ignored in the analysis. Given the fact that there has been little previous investigation of bipolar diode and transistor performance as a function of perimeter-to-area ratio, this work raises the possibility that perimeter recombination may be partly responsible for poor effective minority carrier lifetimes and limited performance obtained in many previous SiC bipolar junction devices.

A theoretical analysis of the current-voltage characteristics of solar cells. [and their energy conversion efficiency

NASA Technical Reports Server (NTRS)

Dunbar, P. M.; Hauser, J. R.

1976-01-01

Various mechanisms which limit the conversion efficiency of silicon solar cells were studied. The effects of changes in solar cell geometry such as layer thickness on performance were examined. The effects of various antireflecting layers were also examined. It was found that any single film antireflecting layer results in a significant surface loss of photons. The use of surface texturing techniques or low loss antireflecting layers can enhance by several percentage points the conversion efficiency of silicon cells. The basic differences between n(+)-p-p(+) and p(+)-n-n(+) cells are treated. A significant part of the study was devoted to the importance of surface region lifetime and heavy doping effects on efficiency. Heavy doping bandgap reduction effects are enhanced by low surface layer lifetimes, and conversely, the reduction in solar cell efficiency due to low surface layer lifetime is further enhanced by heavy doping effects. A series of computer studies is reported which seeks to determine the best cell structure and doping levels for maximum efficiency.

Cost-effectiveness of alternative strategies for integrating MRI into breast cancer screening for women at high risk.

PubMed

Ahern, C H; Shih, Y-C T; Dong, W; Parmigiani, G; Shen, Y

2014-10-14

Magnetic resonance imaging (MRI) is recommended for women at high risk for breast cancer. We evaluated the cost-effectiveness of alternative screening strategies involving MRI. Using a microsimulation model, we generated life histories under different risk profiles, and assessed the impact of screening on quality-adjusted life-years, and lifetime costs, both discounted at 3%. We compared 12 screening strategies combining annual or biennial MRI with mammography and clinical breast examination (CBE) in intervals of 0.5, 1, or 2 years vs without, and reported incremental cost-effectiveness ratios (ICERs). Based on an ICER threshold of $100,000/QALY, the most cost-effective strategy for women at 25% lifetime risk was to stagger MRI and mammography plus CBE every year from age 30 to 74, yielding ICER $58,400 (compared to biennial MRI alone). At 50% lifetime risk and with 70% reduction in MRI cost, the recommended strategy was to stagger MRI and mammography plus CBE every 6 months (ICER=$84,400). At 75% lifetime risk, the recommended strategy is biennial MRI combined with mammography plus CBE every 6 months (ICER=$62,800). The high costs of MRI and its lower specificity are limiting factors for annual screening schedule of MRI, except for women at sufficiently high risk.

Cost-Utility Analysis of Bariatric Surgery in Italy: Results of Decision-Analytic Modelling

PubMed Central

Lucchese, Marcello; Borisenko, Oleg; Mantovani, Lorenzo Giovanni; Cortesi, Paolo Angelo; Cesana, Giancarlo; Adam, Daniel; Burdukova, Elisabeth; Lukyanov, Vasily; Di Lorenzo, Nicola

2017-01-01

Objective To evaluate the cost-effectiveness of bariatric surgery in Italy from a third-party payer perspective over a medium-term (10 years) and a long-term (lifetime) horizon. Methods A state-transition Markov model was developed, in which patients may experience surgery, post-surgery complications, diabetes mellitus type 2, cardiovascular diseases or die. Transition probabilities, costs, and utilities were obtained from the Italian and international literature. Three types of surgeries were considered: gastric bypass, sleeve gastrectomy, and adjustable gastric banding. A base-case analysis was performed for the population, the characteristics of which were obtained from surgery candidates in Italy. Results In the base-case analysis, over 10 years, bariatric surgery led to cost increment of EUR 2,661 and generated additional 1.1 quality-adjusted life years (QALYs). Over a lifetime, surgery led to savings of EUR 8,649, additional 0.5 life years and 3.2 QALYs. Bariatric surgery was cost-effective at 10 years with an incremental cost-effectiveness ratio of EUR 2,412/QALY and dominant over conservative management over a lifetime. Conclusion In a comprehensive decision analytic model, a current mix of surgical methods for bariatric surgery was cost-effective at 10 years and cost-saving over the lifetime of the Italian patient cohort considered in this analysis. PMID:28601866

Long-Term Effects of the Communities That Care Trial on Substance Use, Antisocial Behavior, and Violence Through Age 21 Years.

PubMed

Oesterle, Sabrina; Kuklinski, Margaret R; Hawkins, J David; Skinner, Martie L; Guttmannova, Katarina; Rhew, Isaac C

2018-05-01

To evaluate whether the effects of the Communities That Care (CTC) prevention system, implemented in early adolescence to promote positive youth development and reduce health-risking behavior, endured through age 21 years. We analyzed 9 waves of prospective data collected between 2004 and 2014 from a panel of 4407 participants (grade 5 through age 21 years) in the community-randomized trial of the CTC system in Colorado, Illinois, Kansas, Maine, Oregon, Utah, and Washington State. We used multilevel models to evaluate intervention effects on sustained abstinence, lifetime incidence, and prevalence of past-year substance use, antisocial behavior, and violence. The CTC system increased the likelihood of sustained abstinence from gateway drug use by 49% and antisocial behavior by 18%, and reduced lifetime incidence of violence by 11% through age 21 years. In male participants, the CTC system also increased the likelihood of sustained abstinence from tobacco use by 30% and marijuana use by 24%, and reduced lifetime incidence of inhalant use by 18%. No intervention effects were found on past-year prevalence of these behaviors. Implementation of the CTC prevention system in adolescence reduced lifetime incidence of health-risking behaviors into young adulthood. Clinicaltrials.gov identifier: NCT01088542.

An Undergraduate Experiment on Nuclear Lifetime Measurement Using the Doppler Effect

ERIC Educational Resources Information Center

Campbell, J. L.; And Others

1972-01-01

While designed for a senior undergraduate laboratory, the experiment illustrates the principles involved in the various Doppler techniques currently used in nuclear lifetime studies and demonstrates the versatility of the Ge(Li) detector in applications other than direct energy or intensity measurement. (Author/TS)

Relative influence of meteorological conditions and aerosols on the lifetime of mesoscale convective systems.

PubMed

Chakraborty, Sudip; Fu, Rong; Massie, Steven T; Stephens, Graeme

2016-07-05

Using collocated measurements from geostationary and polar-orbital satellites over tropical continents, we provide a large-scale statistical assessment of the relative influence of aerosols and meteorological conditions on the lifetime of mesoscale convective systems (MCSs). Our results show that MCSs' lifetime increases by 3-24 h when vertical wind shear (VWS) and convective available potential energy (CAPE) are moderate to high and ambient aerosol optical depth (AOD) increases by 1 SD (1σ). However, this influence is not as strong as that of CAPE, relative humidity, and VWS, which increase MCSs' lifetime by 3-30 h, 3-27 h, and 3-30 h per 1σ of these variables and explain up to 36%, 45%, and 34%, respectively, of the variance of the MCSs' lifetime. AOD explains up to 24% of the total variance of MCSs' lifetime during the decay phase. This result is physically consistent with that of the variation of the MCSs' ice water content (IWC) with aerosols, which accounts for 35% and 27% of the total variance of the IWC in convective cores and anvil, respectively, during the decay phase. The effect of aerosols on MCSs' lifetime varies between different continents. AOD appears to explain up to 20-22% of the total variance of MCSs' lifetime over equatorial South America compared with 8% over equatorial Africa. Aerosols over the Indian Ocean can explain 20% of total variance of MCSs' lifetime over South Asia because such MCSs form and develop over the ocean. These regional differences of aerosol impacts may be linked to different meteorological conditions.

Emotional Support, Negative Interaction and DSM IV Lifetime Disorders among Older African Americans: Findings from the National Survey of American Life (NSAL)

PubMed Central

Lincoln, Karen D.; Taylor, Robert Joseph; Bullard, Kai McKeever; Chatters, Linda M.; Himle, Joseph A.; Woodward, Amanda Toler; Jackson, James S.

2010-01-01

Objectives Both emotional support and negative interaction with family members have been linked to mental health. However, few studies have examined the associations between emotional support and negative interaction and psychiatric disorders in late life. This study investigated the relationship between emotional support and negative interaction on lifetime prevalence of mood and anxiety disorders among older African Americans. Design The analyses utilized the National Survey of American Life. Methods Logistic regression and negative binomial regression analyses were used to examine the effect of emotional support and negative interaction with family members on the prevalence of lifetime DSM-IV mood and anxiety disorders. Participants Data from 786 African Americans aged 55 years and older were used. Measurement The DSM-IV World Mental Health Composite International Diagnostic Interview (WMH-CIDI) was used to assess mental disorders. Three dependent variables were investigated: the prevalence of lifetime mood disorders, the prevalence of lifetime anxiety disorders, and the total number of lifetime mood and anxiety disorders. Results Multivariate analysis found that emotional support was not associated with any of the three dependent variables. Negative interaction was significantly and positively associated with the odds of having a lifetime mood disorder, a lifetime anxiety disorder and the number of lifetime mood and anxiety disorders. Conclusions This is the first study to investigate the relationship between emotional support, negative interaction with family members and psychiatric disorders among older African Americans. Negative interaction was a risk factor for mood and anxiety disorders among older African Americans, whereas emotional support was not significant. PMID:20157904

A portable time-domain LED fluorimeter for nanosecond fluorescence lifetime measurements

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

Wang, Hongtao; Salthouse, Christopher D., E-mail: salthouse@ecs.umass.edu; Center for Personalized Health Monitoring, University of Massachusetts, Amherst, Massachusetts 01003

2014-05-15

Fluorescence lifetime measurements are becoming increasingly important in chemical and biological research. Time-domain lifetime measurements offer fluorescence multiplexing and improved handling of interferers compared with the frequency-domain technique. In this paper, an all solid-state, filterless, and highly portable light-emitting-diode based time-domain fluorimeter (LED TDF) is reported for the measurement of nanosecond fluorescence lifetimes. LED based excitation provides more wavelengths options compared to laser diode based excitation, but the excitation is less effective due to the uncollimated beam, less optical power, and longer latency in state transition. Pulse triggering and pre-bias techniques were implemented in our LED TDF to improve themore » peak optical power to over 100 mW. The proposed pulsing circuit achieved an excitation light fall time of less than 2 ns. Electrical resetting technique realized a time-gated photo-detector to remove the interference of the excitation light with fluorescence. These techniques allow the LED fluorimeter to accurately measure the fluorescence lifetime of fluorescein down to concentration of 0.5 μM. In addition, all filters required in traditional instruments are eliminated for the non-attenuated excitation/emission light power. These achievements make the reported device attractive to biochemical laboratories seeking for highly portable lifetime detection devices for developing sensors based on fluorescence lifetime changes. The device was initially validated by measuring the lifetimes of three commercial fluorophores and comparing them with reported lifetime data. It was subsequently used to characterize a ZnSe quantum dot based DNA sensor.« less

New results on finite-time parameter identification and synchronization of uncertain complex dynamical networks with perturbation

NASA Astrophysics Data System (ADS)

Zhao, Hui; Zheng, Mingwen; Li, Shudong; Wang, Weiping

2018-03-01

Some existing papers focused on finite-time parameter identification and synchronization, but provided incomplete theoretical analyses. Such works incorporated conflicting constraints for parameter identification, therefore, the practical significance could not be fully demonstrated. To overcome such limitations, the underlying paper presents new results of parameter identification and synchronization for uncertain complex dynamical networks with impulsive effect and stochastic perturbation based on finite-time stability theory. Novel results of parameter identification and synchronization control criteria are obtained in a finite time by utilizing Lyapunov function and linear matrix inequality respectively. Finally, numerical examples are presented to illustrate the effectiveness of our theoretical results.

Higher speed VCSELs by photon lifetime reduction

NASA Astrophysics Data System (ADS)

Westbergh, Petter; Gustavsson, Johan S.; Kögel, Benjamin; Haglund, Åsa; Larsson, Anders; Joel, Andrew

2011-03-01

The impedance characteristics and the effects of photon lifetime reduction on the performance of high-speed 850 nm VCSELs are investigated. Through S11 measurements and equivalent circuit modeling we show that the parasitic mesa capacitance can be significantly reduced by using multiple oxide layers. By performing a shallow surface etch (25 - 55 nm) on the fabricated VCSELs, we are able to reduce the photon lifetime by up to 80% and thereby significantly improve both static and dynamic properties of the VCSELs. By optimizing the photon lifetime we are able to enhance the 3dB modulation bandwidth of 7 μm oxide aperture VCSELs from 15 GHz to 23 GHz and finally demonstrate errorfree transmission at up to 40 Gbit/s.

Finite-time resilient decentralized control for interconnected impulsive switched systems with neutral delay.

PubMed

Ren, Hangli; Zong, Guangdeng; Hou, Linlin; Yang, Yi

2017-03-01

This paper is concerned with the problem of finite-time control for a class of interconnected impulsive switched systems with neutral delay in which the time-varying delay appears in both the state and the state derivative. The concepts of finite-time boundedness and finite-time stability are respectively extended to interconnected impulsive switched systems with neutral delay for the first time. By applying the average dwell time method, sufficient conditions are first derived to cope with the problem of finite-time boundedness and finite-time stability for interconnected impulsive switched systems with neutral delay. In addition, the purpose of finite-time resilient decentralized control is to construct a resilient decentralized state-feedback controller such that the closed-loop system is finite-time bounded and finite-time stable. All the conditions are formulated in terms of linear matrix inequalities to ensure finite-time boundedness and finite-time stability of the given system. Finally, an example is presented to illustrate the effectiveness of the proposed approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Finite elements and fluid dynamics. [instability effects on solution of nonlinear equations

NASA Technical Reports Server (NTRS)

Fix, G.

1975-01-01

Difficulties concerning a use of the finite element method in the solution of the nonlinear equations of fluid dynamics are partly related to various 'hidden' instabilities which often arise in fluid calculations. The instabilities are typically due to boundary effects or nonlinearities. It is shown that in certain cases these instabilities can be avoided if certain conservation laws are satisfied, and that the latter are often intimately related to finite elements.

Radiation-driven winds of hot stars. VI - Analytical solutions for wind models including the finite cone angle effect

NASA Technical Reports Server (NTRS)

Kudritzki, R. P.; Pauldrach, A.; Puls, J.; Abbott, D. C.

1989-01-01

Analytical solutions for radiation-driven winds of hot stars including the important finite cone angle effect (see Pauldrach et al., 1986; Friend and Abbott, 1986) are derived which approximate the detailed numerical solutions of the exact wind equation of motion very well. They allow a detailed discussion of the finite cone angle effect and provide for given line force parameters k, alpha, delta definite formulas for mass-loss rate M and terminal velocity v-alpha as function of stellar parameters.

The Associations of Naturalistic Classic Psychedelic Use, Mystical Experience, and Creative Problem Solving.

PubMed

Sweat, Noah W; Bates, Larry W; Hendricks, Peter S

2016-01-01

Developing methods for improving creativity is of broad interest. Classic psychedelics may enhance creativity; however, the underlying mechanisms of action are unknown. This study was designed to assess whether a relationship exists between naturalistic classic psychedelic use and heightened creative problem-solving ability and if so, whether this is mediated by lifetime mystical experience. Participants (N = 68) completed a survey battery assessing lifetime mystical experience and circumstances surrounding the most memorable experience. They were then administered a functional fixedness task in which faster completion times indicate greater creative problem-solving ability. Participants reporting classic psychedelic use concurrent with mystical experience (n = 11) exhibited significantly faster times on the functional fixedness task (Cohen's d = -.87; large effect) and significantly greater lifetime mystical experience (Cohen's d = .93; large effect) than participants not reporting classic psychedelic use concurrent with mystical experience. However, lifetime mystical experience was unrelated to completion times on the functional fixedness task (standardized β = -.06), and was therefore not a significant mediator. Classic psychedelic use may increase creativity independent of its effects on mystical experience. Maximizing the likelihood of mystical experience may need not be a goal of psychedelic interventions designed to boost creativity.

Fuzzy Finite-Time Command Filtered Control of Nonlinear Systems With Input Saturation.

PubMed

Yu, Jinpeng; Zhao, Lin; Yu, Haisheng; Lin, Chong; Dong, Wenjie

2017-08-22

This paper considers the fuzzy finite-time tracking control problem for a class of nonlinear systems with input saturation. A novel fuzzy finite-time command filtered backstepping approach is proposed by introducing the fuzzy finite-time command filter, designing the new virtual control signals and the modified error compensation signals. The proposed approach not only holds the advantages of the conventional command-filtered backstepping control, but also guarantees the finite-time convergence. A practical example is included to show the effectiveness of the proposed method.

Finite-time hybrid projective synchronization of the drive-response complex networks with distributed-delay via adaptive intermittent control

NASA Astrophysics Data System (ADS)

Cheng, Lin; Yang, Yongqing; Li, Li; Sui, Xin

2018-06-01

This paper studies the finite-time hybrid projective synchronization of the drive-response complex networks. In the model, general transmission delays and distributed delays are also considered. By designing the adaptive intermittent controllers, the response network can achieve hybrid projective synchronization with the drive system in finite time. Based on finite-time stability theory and several differential inequalities, some simple finite-time hybrid projective synchronization criteria are derived. Two numerical examples are given to illustrate the effectiveness of the proposed method.

Refinement of Out of Circularity and Thickness Measurements of a Cylinder for Finite Element Analysis

DTIC Science & Technology

2016-09-01

UNCLASSIFIED UNCLASSIFIED Refinement of Out of Circularity and Thickness Measurements of a Cylinder for Finite Element Analysis...significant effect on the collapse strength and must be accurately represented in finite element analysis to obtain accurate results. Often it is necessary...to interpolate measurements from a relatively coarse grid to a refined finite element model and methods that have wide general acceptance are

Angular Random Walk Estimation of a Time-Domain Switching Micromachined Gyroscope

DTIC Science & Technology

2016-10-19

1 2. PARAMETRIC SYSTEM IDENTIFICATION BASED ON TIME-DOMAIN SWITCHING ........ 2 3. FINITE ELEMENT MODELING OF RESONATOR...8 3. FINITE ELEMENT MODELING OF RESONATOR This section details basic finite element modeling of the resonator used with the TDSMG. While it...Based on finite element simulations of the employed resonator, it is found that the effects of thermomechanical noise is on par with 10 ps of timing

Comparison of finite-difference schemes for analysis of shells of revolution. [stress and free vibration analysis

NASA Technical Reports Server (NTRS)

Noor, A. K.; Stephens, W. B.

1973-01-01

Several finite difference schemes are applied to the stress and free vibration analysis of homogeneous isotropic and layered orthotropic shells of revolution. The study is based on a form of the Sanders-Budiansky first-approximation linear shell theory modified such that the effects of shear deformation and rotary inertia are included. A Fourier approach is used in which all the shell stress resultants and displacements are expanded in a Fourier series in the circumferential direction, and the governing equations reduce to ordinary differential equations in the meridional direction. While primary attention is given to finite difference schemes used in conjunction with first order differential equation formulation, comparison is made with finite difference schemes used with other formulations. These finite difference discretization models are compared with respect to simplicity of application, convergence characteristics, and computational efficiency. Numerical studies are presented for the effects of variations in shell geometry and lamination parameters on the accuracy and convergence of the solutions obtained by the different finite difference schemes. On the basis of the present study it is shown that the mixed finite difference scheme based on the first order differential equation formulation and two interlacing grids for the different fundamental unknowns combines a number of advantages over other finite difference schemes previously reported in the literature.

Effects of a finite outer scale on the measurement of atmospheric-turbulence statistics with a Hartmann wave-front sensor.

PubMed

Feng, Shen; Wenhan, Jiang

2002-06-10

Phase-structure and aperture-averaged slope-correlated functions with a finite outer scale are derived based on the Taylor hypothesis and a generalized spectrum, such as the von Kármán modal. The effects of the finite outer scale on measuring and determining the character of atmospheric-turbulence statistics are shown especially for an approximately 4-m class telescope and subaperture. The phase structure function and atmospheric coherent length based on the Kolmogorov model are approximations of the formalism we have derived. The analysis shows that it cannot be determined whether the deviation from the power-law parameter of Kolmogorov turbulence is caused by real variations of the spectrum or by the effect of the finite outer scale.

On the impact of multi-axial stress states on trailing edge bondlines in wind turbine rotor blades

NASA Astrophysics Data System (ADS)

Noever Castelos, Pablo; Balzani, Claudio

2016-09-01

For a reliable design of wind turbine systems all of their components have to be designed to withstand the loads appearing in the turbine's lifetime. When performed in an integral manner this is called systems engineering, and is exceptionally important for components that have an impact on the entire wind turbine system, such as the rotor blade. Bondlines are crucial subcomponents of rotor blades, but they are not much recognized in the wind energy research community. However, a bondline failure can lead to the loss of a rotor blade, and potentially of the entire turbine, and is extraordinarily relevant to be treated with strong emphasis when designing a wind turbine. Modern wind turbine rotor blades with lengths of 80 m and more offer a degree of flexibility that has never been seen in wind energy technology before. Large deflections result in high strains in the adhesive connections, especially at the trailing edge. The latest edition of the DNV GL guideline from end of 2015 demands a three-dimensional stress analysis of bondlines, whereas before an isolated shear stress proof was sufficient. In order to quantify the lack of safety from older certification guidelines this paper studies the influence of multi-axial stress states on the ultimate and fatigue load resistance of trailing edge adhesive bonds. For this purpose, detailed finite element simulations of the IWES IWT-7.5-164 reference wind turbine blades are performed. Different yield criteria are evaluated for the prediction of failure and lifetime. The results show that the multi-axial stress state is governed by span-wise normal stresses. Those are evidently not captured in isolated shear stress proofs, yielding non-conservative estimates of lifetime and ultimate load resistance. This finding highlights the importance to include a three-dimensional stress state in the failure analysis of adhesive bonds in modern wind turbine rotor blades, and the necessity to perform a three-dimensional characterization of adhesive materials.

Area Coverage of Expanding E.T. Signals in the Galaxy: SETI and Drake’s N

NASA Astrophysics Data System (ADS)

Grimaldi, Claudio; Marcy, Geoffrey W.; Tellis, Nathaniel K.; Drake, Frank

2018-05-01

The Milky Way Galaxy contains an unknown number, N, of civilizations that emit electromagnetic radiation (of unknown wavelengths) over a finite lifetime, L. Here we are assuming that the radiation is not produced indefinitely, but within L as a result of some unknown limiting event. When a civilization stops emitting, the radiation continues traveling outward at the speed of light, c, but is confined within a shell wall having constant thickness, cL. We develop a simple model of the Galaxy that includes both the birthrate and detectable lifetime of civilizations to compute the possibility of a SETI detection at the Earth. Two cases emerge for radiation shells that are (1) thinner than or (2) thicker than the size of the Galaxy, corresponding to detectable lifetimes, L, less than or greater than the light-travel time, ∼100,000 years, across the Milky Way, respectively. For case (1), each shell wall has a thickness smaller than the size of the Galaxy and intersects the Galactic plane in a donut shape (annulus) that fills only a fraction of the Galaxy’s volume, inhibiting SETI detection. But the ensemble of such shell walls may still fill our Galaxy, and indeed may overlap locally, given a sufficiently high birthrate of detectable civilizations. In the second case, each radiation shell is thicker than the size of our Galaxy. Yet, the ensemble of walls may or may not yield a SETI detection depending on the civilization birthrate. We compare the number of different electromagnetic transmissions arriving at Earth to Drake’s N, the number of currently emitting civilizations, showing that they are equal to each other for both cases (1) and (2). However, for L < 100,000 years, the transmissions arriving at Earth may come from distant civilizations long extinct, while civilizations still alive are sending signals yet to arrive.

A Greatly Under-Appreciated Fundamental Principle of Physical Organic Chemistry

PubMed Central

Cox, Robin A.

2011-01-01

If a species does not have a finite lifetime in the reaction medium, it cannot be a mechanistic intermediate. This principle was first enunciated by Jencks, as the concept of an enforced mechanism. For instance, neither primary nor secondary carbocations have long enough lifetimes to exist in an aqueous medium, so SN1 reactions involving these substrates are not possible, and an SN2 mechanism is enforced. Only tertiary carbocations and those stabilized by resonance (benzyl cations, acylium ions) are stable enough to be reaction intermediates. More importantly, it is now known that neither H3O+ nor HO− exist as such in dilute aqueous solution. Several recent high-level calculations on large proton clusters are unable to localize the positive charge; it is found to be simply “on the cluster” as a whole. The lifetime of any ionized water species is exceedingly short, a few molecular vibrations at most; the best experimental study, using modern IR instrumentation, has the most probable hydrated proton structure as H13O6+, but only an estimated quarter of the protons are present even in this form at any given instant. Thanks to the Grotthuss mechanism of chain transfer along hydrogen bonds, in reality a proton or a hydroxide ion is simply instantly available anywhere it is needed for reaction. Important mechanistic consequences result. Any charged oxygen species (e.g., a tetrahedral intermediate) is also not going to exist long enough to be a reaction intermediate, unless the charge is stabilized in some way, usually by resonance. General acid catalysis is the rule in reactions in concentrated aqueous acids. The Grotthuss mechanism also means that reactions involving neutral water are favored; the solvent is already highly structured, so the entropy involved in bringing several solvent molecules to the reaction center is unimportant. Examples are given. PMID:22272074

The modifier effects of chymotrypsin and trypsin enzymes on fluorescence lifetime distribution of "N-(1-pyrenyl)maleimide-bovine serum albumin" complex.

PubMed

Özyiğit, İbrahim Ethem; Karakuş, Emine; Pekcan, Önder

2016-02-05

Chymotrypsin and trypsin are the well known proteolytic enzymes, both of which are synthesized in the pancreas as their precursors - the inactive forms; chymotrypsinogen and trypsinogen - and then are released into the duodenum to cut proteins into smaller peptides. In this paper, the effects of activities of chymotrypsin and trypsin enzymes on fluorescence lifetime distributions of the substrat bovine serum albumin (BSA) modified with N-(1-pyrenyl)maleimide (PM) were examined. In the labeling study of BSA with PM, it is aimed to attach PM to the single free thiol (Cys34) and to all the free amine groups in accessible positions in order to produce excimers of pyrene planes of the possible highest amount to form the lifetime distributions in the widest range, that may show specifically distinguishing changes resulting from the activities of the proteases. The time resolved spectrofluorometer was used to monitor fluorescence decays, which were analyzed by using the exponential series method (ESM) to obtain the changes of lifetime distributions. After the exposure of the synthesized substrat PM-BSA to the enzymes, the fluorescence lifetime distributions exhibited different structures which were attributed to the different activities of the proteases. Copyright © 2015 Elsevier B.V. All rights reserved.

Long-range ballistic motion and coherent flow of long-lifetime polaritons

NASA Astrophysics Data System (ADS)

Steger, Mark; Liu, Gangqiang; Nelsen, Bryan; Gautham, Chitra; Snoke, David W.; Balili, Ryan; Pfeiffer, Loren; West, Ken

2013-12-01

Exciton polaritons can be created in semiconductor microcavities. These quasiparticles act as weakly interacting bosons with very light mass, of the order of 10-4 times the vacuum electron mass. Many experiments have shown effects which can be viewed as due to a Bose-Einstein condensate, or quasicondensate, of these particles. The lifetime of the particles in most of those experiments has been of the order of a few picoseconds, leading to significant nonequilibrium effects. By increasing the cavity quality, we have made samples with longer polariton lifetimes. With a photon lifetime on the order of 100-200 ps, polaritons in these structures can not only come closer to reaching true thermal equilibrium, a desired feature for many researchers working in this field, but they can also travel much longer distances. We observe the polaritons to ballistically travel on the order of 1 mm, and at higher densities we see transport of a coherent condensate, or quasicondensate, over comparable distances. In this paper we report a quantitative analysis of the flow of the polaritons both in a low-density, classical regime, and in the coherent regime at higher density. Our analysis gives us a measure of the intrinsic lifetime for photon decay from the microcavity and a measure of the strength of interactions of the polaritons.

Oocyte stem cells: fact or fantasy?

PubMed

Horan, Corrina J; Williams, Suzannah A

2017-07-01

For many decades, the dogma prevailed that female mammals had a finite pool of oocytes at birth and this was gradually exhausted during a lifetime of reproductive function. However, in 2004, a new era began in the field of female oogenesis. A study was published that appeared to detect oocyte-stem cells capable of generating new eggs within mouse ovaries. This study was highly controversial and the years since this initial finding have produced extensive research and even more extensive debate into their possibility. Unequivocal evidence testifying to the existence of oocyte-stem cells (OSCs) has yet to be produced, meanwhile the spectrum of views from both sides of the debate are wide-ranging and surprisingly passionate. Although recent studies have presented some convincing results that germ cells exist and are capable of creating new oocytes, many questions remain. Are these cells present in humans? Do they exist in physiological conditions in a dormant state? This comprehensive review first examines where and how the dogma of a finite pool was established, how this has been challenged over the years and addresses the most pertinent questions as to the current status of their existence, their role in female fertility, and perhaps most importantly, if they do exist, how can we harness these cells to improve a woman's oocyte reserve and treat conditions such as premature ovarian insufficiency (POI: also known as premature ovarian failure, POF). © 2017 Society for Reproduction and Fertility.

Finite Element Creep-Fatigue Analysis of a Welded Furnace Roll for Identifying Failure Root Cause

NASA Astrophysics Data System (ADS)

Yang, Y. P.; Mohr, W. C.

2015-11-01

Creep-fatigue induced failures are often observed in engineering components operating under high temperature and cyclic loading. Understanding the creep-fatigue damage process and identifying failure root cause are very important for preventing such failures and improving the lifetime of engineering components. Finite element analyses including a heat transfer analysis and a creep-fatigue analysis were conducted to model the cyclic thermal and mechanical process of a furnace roll in a continuous hot-dip coating line. Typically, the roll has a short life, <1 year, which has been a problem for a long time. The failure occurred in the weld joining an end bell to a roll shell and resulted in the complete 360° separation of the end bell from the roll shell. The heat transfer analysis was conducted to predict the temperature history of the roll by modeling heat convection from hot air inside the furnace. The creep-fatigue analysis was performed by inputting the predicted temperature history and applying mechanical loads. The analysis results showed that the failure was resulted from a creep-fatigue mechanism rather than a creep mechanism. The difference of material properties between the filler metal and the base metal is the root cause for the roll failure, which induces higher creep strain and stress in the interface between the weld and the HAZ.

Chiral crossover transition in a finite volume

NASA Astrophysics Data System (ADS)

Shi, Chao; Jia, Wenbao; Sun, An; Zhang, Liping; Zong, Hongshi

2018-02-01

Finite volume effects on the chiral crossover transition of strong interactions at finite temperature are studied by solving the quark gap equation within a cubic volume of finite size L. With the anti-periodic boundary condition, our calculation shows the chiral quark condensate, which characterizes the strength of dynamical chiral symmetry breaking, decreases as L decreases below 2.5 fm. We further study the finite volume effects on the pseudo-transition temperature {T}{{c}} of the crossover, showing a significant decrease in {T}{{c}} as L decreases below 3 fm. Supported by National Natural Science Foundation of China (11475085, 11535005, 11690030, 51405027), the Fundamental Research Funds for the Central Universities (020414380074), China Postdoctoral Science Foundation (2016M591808) and Open Research Foundation of State Key Lab. of Digital Manufacturing Equipment & Technology in Huazhong University of Science & Technology (DMETKF2015015)

Finite Feedback Cycling in Structural Equation Models

ERIC Educational Resources Information Center

Hayduk, Leslie A.

2009-01-01

In models containing reciprocal effects, or longer causal loops, the usual effect estimates assume that any effect touching a loop initiates an infinite cycling of effects around that loop. The real world, in contrast, might permit only finite feedback cycles. I use a simple hypothetical model to demonstrate that if the world permits only a few…

Controlled tuning of the radiative lifetime in InAs self-assembled quantum dots through vertical ordering

NASA Astrophysics Data System (ADS)

Colocci, M.; Vinattieri, A.; Lippi, L.; Bogani, F.; Rosa-Clot, M.; Taddei, S.; Bosacchi, A.; Franchi, S.; Frigeri, P.

1999-01-01

Multilayer structures of InAs quantum dots have been studied by means of photoluminescence techniques. A strong increase of the radiative lifetime with increasing number of stacked dot layers has been observed at low temperatures. Moreover, a strong temperature dependence of the radiative lifetime, which is not present in the single layer samples, has been found in the multistacked structures. The observed effects are nicely explained as a consequence of the electronic coupling between electrons and holes induced by vertical ordering.

How to Reach a Thousand-Second in-Plane Polarization Lifetime with 0.97 - GeV / c Deuterons in a Storage Ring

DOE PAGES

Guidoboni, G.; Stephenson, E.; Andrianov, S.; ...

2016-07-28

Here, we observe a deuteron beam polarization lifetime near 1000 s in the horizontal plane of a magnetic storage ring (COSY). This long spin coherence time is maintained through a combination of beam bunching, electron cooling, sextupole field corrections, and the suppression of collective effects through beam current limits. This record lifetime is required for a storage ring search for an intrinsic electric dipole moment on the deuteron at a statistical sensitivity level approaching 10 -29 $e$ cm.

School-Related Factors Affecting High School Seniors' Methamphetamine Use

ERIC Educational Resources Information Center

Stanley, Jarrod M.; Lo, Celia C.

2009-01-01

Data from the 2005 Monitoring the Future survey were used to examine relationships between school-related factors and high school seniors' lifetime methamphetamine use. The study applied logistic regression techniques to evaluate effects of social bonding variables and social learning variables on likelihood of lifetime methamphetamine use. The…

Infertility and Life Satisfaction among Women

ERIC Educational Resources Information Center

McQuillan, Julia; Stone, Rosalie A. Torres; Greil, Arthur L.

2007-01-01

Using data from a random sample of 580 midwestern women, the authors explore the association between lifetime infertility and life satisfaction. Past research shows lower life satisfaction among those seeking help for infertility. The authors find no direct effects of lifetime infertility, regardless of perception of a problem, on life…

THE EFFECTS OF TRANSIENTS ON PHOTOSPHERIC AND CHROMOSPHERIC POWER DISTRIBUTIONS

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

Samanta, T.; Banerjee, D.; Pant, V.

2016-09-01

We have observed a quiet-Sun region with the Swedish 1 m Solar Telescope equipped with the CRISP Imaging SpectroPolarimeter. High-resolution, high-cadence, H α line scanning images were taken to observe different layers of the solar atmosphere from the photosphere to upper chromosphere. We study the distribution of power in different period bands at different heights. Power maps of the upper photosphere and the lower chromosphere show suppressed power surrounding the magnetic-network elements, known as “magnetic shadows.” These also show enhanced power close to the photosphere, traditionally referred to as “power halos.” The interaction between acoustic waves and inclined magnetic fieldsmore » is generally believed to be responsible for these two effects. In this study we explore whether small-scale transients can influence the distribution of power at different heights. We show that the presence of transients, like mottles, Rapid Blueshifted Excursions (RBEs), and Rapid Redshifted Excursions (RREs), can strongly influence the power maps. The short and finite lifetime of these events strongly affects all power maps, potentially influencing the observed power distribution. We show that Doppler-shifted transients like RBEs and RREs that occur ubiquitously can have a dominant effect on the formation of the power halos in the quiet Sun. For magnetic shadows, transients like mottles do not seem to have a significant effect on the power suppression around 3 minutes, and wave interaction may play a key role here. Our high-cadence observations reveal that flows, waves, and shocks manifest in the presence of magnetic fields to form a nonlinear magnetohydrodynamic system.« less

Topological quantum error correction in the Kitaev honeycomb model

NASA Astrophysics Data System (ADS)

Lee, Yi-Chan; Brell, Courtney G.; Flammia, Steven T.

2017-08-01

The Kitaev honeycomb model is an approximate topological quantum error correcting code in the same phase as the toric code, but requiring only a 2-body Hamiltonian. As a frustrated spin model, it is well outside the commuting models of topological quantum codes that are typically studied, but its exact solubility makes it more amenable to analysis of effects arising in this noncommutative setting than a generic topologically ordered Hamiltonian. Here we study quantum error correction in the honeycomb model using both analytic and numerical techniques. We first prove explicit exponential bounds on the approximate degeneracy, local indistinguishability, and correctability of the code space. These bounds are tighter than can be achieved using known general properties of topological phases. Our proofs are specialized to the honeycomb model, but some of the methods may nonetheless be of broader interest. Following this, we numerically study noise caused by thermalization processes in the perturbative regime close to the toric code renormalization group fixed point. The appearance of non-topological excitations in this setting has no significant effect on the error correction properties of the honeycomb model in the regimes we study. Although the behavior of this model is found to be qualitatively similar to that of the standard toric code in most regimes, we find numerical evidence of an interesting effect in the low-temperature, finite-size regime where a preferred lattice direction emerges and anyon diffusion is geometrically constrained. We expect this effect to yield an improvement in the scaling of the lifetime with system size as compared to the standard toric code.

Fluorescence lifetime measurements of native and glycated human serum albumin and bovine serum albumin

NASA Astrophysics Data System (ADS)

Joshi, Narahari V.; Joshi, Virgina O. d.; Contreras, Silvia; Gil, Herminia; Medina, Honorio; Siemiarczuk, Aleksander

1999-05-01

Nonenzymatic glycation, also known as Maillard reaction, plays an important role in the secondary complications of the diabetic pathology and aging, therefore, human serum albumin (HSA) and bovine serum albumin (BSA) were glycated by a conventional method in our laboratory using glucose as the glycating agent. Fluorescence lifetime measurements were carried out with a laser strobe fluorometer equipped with a nitrogen/dye laser and a frequency doubler as a pulsed excitation source. The samples were excited at 295 nm and the emission spectra were recorded at 345 nm. The obtained decay curves were tried for double and triple exponential functions. It has been found that the shorter lifetime increases for glycated proteins as compared with that of the native ones. For example, in the case of glycated BSA the lifetime increased from 1.36 ns to 2.30 ns. Similarly, for HSA, the lifetime increases from 1.58 ns to 2.26 ns. Meanwhile, the longer lifetime changed very slightly for both proteins (from 6.52 ns to 6.72 ns). The increase in the lifetime can be associated with the environmental effect; originated from the attachment of glucose to some lysine residues. A good example is Trp 214 which is in the cage of Lys 225, Lys 212, Lys 233, Lys 205, Lys 500, Lys 199 and Lys 195. If fluorescence lifetime technique is calibrated and properly used it could be employed for assessing glycation of proteins.

Stabilized Finite Elements in FUN3D

NASA Technical Reports Server (NTRS)

Anderson, W. Kyle; Newman, James C.; Karman, Steve L.

2017-01-01

A Streamlined Upwind Petrov-Galerkin (SUPG) stabilized finite-element discretization has been implemented as a library into the FUN3D unstructured-grid flow solver. Motivation for the selection of this methodology is given, details of the implementation are provided, and the discretization for the interior scheme is verified for linear and quadratic elements by using the method of manufactured solutions. A methodology is also described for capturing shocks, and simulation results are compared to the finite-volume formulation that is currently the primary method employed for routine engineering applications. The finite-element methodology is demonstrated to be more accurate than the finite-volume technology, particularly on tetrahedral meshes where the solutions obtained using the finite-volume scheme can suffer from adverse effects caused by bias in the grid. Although no effort has been made to date to optimize computational efficiency, the finite-element scheme is competitive with the finite-volume scheme in terms of computer time to reach convergence.

Finite-Time and Fixed-Time Cluster Synchronization With or Without Pinning Control.

PubMed

Liu, Xiwei; Chen, Tianping

2018-01-01

In this paper, the finite-time and fixed-time cluster synchronization problem for complex networks with or without pinning control are discussed. Finite-time (or fixed-time) synchronization has been a hot topic in recent years, which means that the network can achieve synchronization in finite-time, and the settling time depends on the initial values for finite-time synchronization (or the settling time is bounded by a constant for any initial values for fixed-time synchronization). To realize the finite-time and fixed-time cluster synchronization, some simple distributed protocols with or without pinning control are designed and the effectiveness is rigorously proved. Several sufficient criteria are also obtained to clarify the effects of coupling terms for finite-time and fixed-time cluster synchronization. Especially, when the cluster number is one, the cluster synchronization becomes the complete synchronization problem; when the network has only one node, the coupling term between nodes will disappear, and the synchronization problem becomes the simplest master-slave case, which also includes the stability problem for nonlinear systems like neural networks. All these cases are also discussed. Finally, numerical simulations are presented to demonstrate the correctness of obtained theoretical results.

Lifetime and 5 years risk of breast cancer and attributable risk factor according to Gail model in Iranian women

PubMed Central

Mohammadbeigi, Abolfazl; Mohammadsalehi, Narges; Valizadeh, Razieh; Momtaheni, Zeinab; Mokhtari, Mohsen; Ansari, Hossein

2015-01-01

Introduction: Breast cancer is the most commonly diagnosed cancers in women worldwide and in Iran. It is expected to account for 29% of all new cancers in women at 2015. This study aimed to assess the 5 years and lifetime risk of breast cancer according to Gail model, and to evaluate the effect of other additional risk factors on the Gail risk. Materials and Methods: A cross sectional study conducted on 296 women aged more than 34-year-old in Qom, Center of Iran. Breast Cancer Risk Assessment Tool calculated the Gail risk for each subject. Data were analyzed by paired t-test, independent t-test, and analysis of variance in bivariate approach to evaluate the effect of each factor on Gail risk. Multiple linear regression models with stepwise method were used to predict the effect of each variable on the Gail risk. Results: The mean age of the participants was 47.8 ± 8.8-year-old and 47% have Fars ethnicity. The 5 years and lifetime risk was 0.37 ± 0.18 and 4.48 ± 0.925%, respectively. It was lower than the average risk in same race and age women (P < 0.001). Being single, positive family history of breast cancer, positive history of biopsy, and radiotherapy as well as using nonhormonal contraceptives were related to higher lifetime risk (P < 0.05). Moreover, a significant direct correlation observed between lifetime risk and body mass index, age of first live birth, and menarche age. While an inversely correlation observed between lifetimes risk of breast cancer and total month of breast feeding duration and age. Conclusion: Based on our results, the 5 years and lifetime risk of breast cancer according to Gail model was lower than the same race and age. Moreover, by comparison with national epidemiologic indicators about morbidity and mortality of breast cancer, it seems that the Gail model overestimate the risk of breast cancer in Iranian women. PMID:26229355

Cost-Effectiveness of Intensive versus Standard Blood-Pressure Control.

PubMed

Bress, Adam P; Bellows, Brandon K; King, Jordan B; Hess, Rachel; Beddhu, Srinivasan; Zhang, Zugui; Berlowitz, Dan R; Conroy, Molly B; Fine, Larry; Oparil, Suzanne; Morisky, Donald E; Kazis, Lewis E; Ruiz-Negrón, Natalia; Powell, Jamie; Tamariz, Leonardo; Whittle, Jeff; Wright, Jackson T; Supiano, Mark A; Cheung, Alfred K; Weintraub, William S; Moran, Andrew E

2017-08-24

In the Systolic Blood Pressure Intervention Trial (SPRINT), adults at high risk for cardiovascular disease who received intensive systolic blood-pressure control (target, <120 mm Hg) had significantly lower rates of death and cardiovascular disease events than did those who received standard control (target, <140 mm Hg). On the basis of these data, we wanted to determine the lifetime health benefits and health care costs associated with intensive control versus standard control. We used a microsimulation model to apply SPRINT treatment effects and health care costs from national sources to a hypothetical cohort of SPRINT-eligible adults. The model projected lifetime costs of treatment and monitoring in patients with hypertension, cardiovascular disease events and subsequent treatment costs, treatment-related risks of serious adverse events and subsequent costs, and quality-adjusted life-years (QALYs) for intensive control versus standard control of systolic blood pressure. We determined that the mean number of QALYs would be 0.27 higher among patients who received intensive control than among those who received standard control and would cost approximately $47,000 more per QALY gained if there were a reduction in adherence and treatment effects after 5 years; the cost would be approximately $28,000 more per QALY gained if the treatment effects persisted for the remaining lifetime of the patient. Most simulation results indicated that intensive treatment would be cost-effective (51 to 79% below the willingness-to-pay threshold of $50,000 per QALY and 76 to 93% below the threshold of $100,000 per QALY), regardless of whether treatment effects were reduced after 5 years or persisted for the remaining lifetime. In this simulation study, intensive systolic blood-pressure control prevented cardiovascular disease events and prolonged life and did so at levels below common willingness-to-pay thresholds per QALY, regardless of whether benefits were reduced after 5 years or persisted for the patient's remaining lifetime. (Funded by the National Heart, Lung, and Blood Institute and others; SPRINT ClinicalTrials.gov number, NCT01206062 .).

Finite plate thickness effects on the Rayleigh-Taylor instability in elastic-plastic materials

NASA Astrophysics Data System (ADS)

Polavarapu, Rinosh; Banerjee, Arindam

2017-11-01

The majority of theoretical studies have tackled the Rayleigh-Taylor instability (RTI) problem in solids using an infinitely thick plate. Recent theoretical studies by Piriz et al. (PRE 95, 053108, 2017) have explored finite thickness effects. We seek to validate this recent theoretical estimate experimentally using our rotating wheel RTI experiment in an accelerated elastic-plastic material. The test section consists of a container filled with air and mayonnaise (a non-Newtonian emulsion) with an initial perturbation between two materials. The plate thickness effects are studied by varying the depth of the soft-solid. A set of experiments is run by employing different initial conditions with different container dimensions. Additionally, the effect of acceleration rate (driving pressure rise time) on the instability threshold with reference to the finite thickness will also be inspected. Furthermore, the experimental results are compared to the analytical strength models related to finite thickness effects on RTI. Authors acknowledge financial support from DOE-SSAA Grant # DE-NA0003195 and LANL subcontract #370333.

Pelvic Floor Consequences of Cesarean Delivery on Maternal Request in Women with a Single Birth: A Cost-effectiveness Analysis

PubMed Central

Ivy, Julie S.; Patel, Divya A.; Patel, Sejal N.; Smith, Dean G.; Ransom, Scott B.; Fenner, Dee; DeLancey, John O.L.

2010-01-01

Abstract Background The potential benefit in preventing pelvic floor disorders (PFDs) is a frequently cited reason for requesting or performing cesarean delivery on maternal request (CDMR). However, for primigravid women without medical/obstetric indications, the lifetime cost-effectiveness of CDMR remains unknown, particularly with regard to lifelong pelvic floor consequences. Our objective was to assess the cost-effectiveness of CDMR in comparison to trial of labor (TOL) for primigravid women without medical/obstetric indications with a single childbirth over their lifetime, while explicitly accounting for the management of PFD throughout the lifetime. Methods We used Monte Carlo simulation of a decision model containing 249 chance events and 101 parameters depicting lifelong maternal and neonatal outcomes in the following domains: actual mode of delivery, emergency hysterectomy, transient maternal morbidity and mortality, perinatal morbidity and mortality, and the lifelong management of PFDs. Parameter estimates were obtained from published literature. The analysis was conducted from a societal perspective. All costs and quality-adjusted life-years (QALYs) were discounted to the present value at childbirth. Results The estimated mean cost and QALYs were $14,259 (95% confidence interval [CI] $8,964-$24,002) and 58.21 (95% CI 57.43-58.67) for CDMR and $13,283 (95% CI $7,861-$23,829) and 57.87 (95% CI 56.97-58.46) for TOL over the combined lifetime of the mother and the child. Parameters related to PFDs play an important role in determining cost and quality of life. Conclusions When a woman without medical/obstetric indications has only one childbirth in her lifetime, cost-effectiveness analysis does not reveal a clearly preferable mode of delivery. PMID:20088671

The Economic Impact of Acetabular Labral Tears: A Cost-effectiveness Analysis Comparing Hip Arthroscopic Surgery and Structured Rehabilitation Alone in Patients Without Osteoarthritis.

PubMed

Lodhia, Parth; Gui, Chengcheng; Chandrasekaran, Sivashankar; Suarez-Ahedo, Carlos; Dirschl, Douglas R; Domb, Benjamin G

2016-07-01

Hip arthroscopic surgery has emerged as a successful procedure to manage acetabular labral tears and concurrent hip injuries, which if left untreated, may contribute to hip osteoarthritis (OA). Therefore, it is essential to analyze the economic impact of this treatment option. To investigate the cost-effectiveness of hip arthroscopic surgery versus structured rehabilitation alone for acetabular labral tears, to examine the effects of age on cost-effectiveness, and to estimate the rate of symptomatic OA and total hip arthroplasty (THA) in both treatment arms over a lifetime horizon. Economic and decision analysis; Level of evidence, 2. A cost-effectiveness analysis of hip arthroscopic surgery compared with structured rehabilitation for symptomatic labral tears was performed using a Markov decision model constructed over a lifetime horizon. It was assumed that patients did not have OA. Direct costs (in 2014 United States dollars), utilities of health states (in quality-adjusted life years [QALYs] gained), and probabilities of transitioning between health states were estimated from a comprehensive literature review. Costs were estimated using national averages of Medicare reimbursements, adjusted for all payers in the United States from a societal perspective. Utilities were estimated from the Harris Hip Score. Cost-effectiveness was assessed using the incremental cost-effectiveness ratio (ICER). One-way and probabilistic sensitivity analyses were performed to determine the effect of uncertainty on the model outcomes. For a cohort representative of patients undergoing hip arthroscopic surgery at our facility, arthroscopic surgery was more costly (additional $2653) but generated more utility (additional 3.94 QALYs) compared with rehabilitation over a lifetime. The mean ICER was $754/QALY, well below the conventional willingness to pay of $50,000/QALY. Arthroscopic surgery was cost-effective for 94.5% of patients. Although arthroscopic surgery decreased in cost-effectiveness with increasing age, arthroscopic surgery remained more cost-effective than rehabilitation for patients in the second to seventh decades of life. The lifetime incidence of symptomatic hip OA was over twice as high for patients treated with rehabilitation compared with arthroscopic surgery. The preferred treatment was sensitive to the utility after successful hip arthroscopic surgery, although the utility at which arthroscopic surgery becomes less cost-effective than rehabilitation is far below our best estimate. For older patients, the lifetime cost of arthroscopic surgery was greater, while the lifetime utility of arthroscopic surgery was less, approaching that of the rehabilitation arm. Hip arthroscopic surgery is more cost-effective and results in a considerably lower incidence of symptomatic OA than structured rehabilitation alone in treating symptomatic labral tears of patients in the second to seventh decades of life without pre-existing OA. © 2016 The Author(s).

Characterization of atomic spin polarization lifetime of cesium vapor cells with neon buffer gas

NASA Astrophysics Data System (ADS)

Lou, Janet W.; Cranch, Geoffrey A.

2018-02-01

The dephasing time of spin-polarized atoms in an atomic vapor cell plays an important role in determining the stability of vapor-cell clocks as well as the sensitivity of optically-pumped magnetometers. The presence of a buffer gas can extend the lifetime of these atoms. Many vapor cell systems operate at a fixed (often elevated) temperature. For ambient temperature operation with no temperature control, it is necessary to characterize the temperature dependence as well. We present a spin-polarization lifetime study of Cesium vapor cells with different buffer gas pressures, and find good agreement with expectations based on the combined effects of wall collisions, spin exchange, and spin destruction. For our (7.5 mm diameter) vapor cells, the lifetime can be increased by two orders of magnitude by introducing Ne buffer gas up to 100 Torr. Additionally, the dependence of the lifetime on temperature is measured (25 - 47 oC) and simulated for the first time to our knowledge with reasonable agreement.

The roles of carrier concentration and interface, bulk, and grain-boundary recombination for 25% efficient CdTe solar cells

DOE PAGES

Kanevce, A.; Reese, Matthew O.; Barnes, T. M.; ...

2017-06-06

CdTe devices have reached efficiencies of 22% due to continuing improvements in bulk material properties, including minority carrier lifetime. Device modeling has helped to guide these device improvements by quantifying the impacts of material properties and different device designs on device performance. One of the barriers to truly predictive device modeling is the interdependence of these material properties. For example, interfaces become more critical as bulk properties, particularly, hole density and carrier lifetime, increase. We present device-modeling analyses that describe the effects of recombination at the interfaces and grain boundaries as lifetime and doping of the CdTe layer change. Themore » doping and lifetime should be priorities for maximizing open-circuit voltage (V oc) and efficiency improvements. However, interface and grain boundary recombination become bottlenecks for device performance at increased lifetime and doping levels. In conclusion, this work quantifies and discusses these emerging challenges for next-generation CdTe device efficiency.« less

Resolving the neutron lifetime puzzle

NASA Astrophysics Data System (ADS)

Mumm, Pieter

2018-05-01

Free electrons and protons are stable, but outside atomic nuclei, free neutrons decay into a proton, electron, and antineutrino through the weak interaction, with a lifetime of ∼880 s (see the figure). The most precise measurements have stated uncertainties below 1 s (0.1%), but different techniques, although internally consistent, disagree by 4 standard deviations given the quoted uncertainties. Resolving this “neutron lifetime puzzle” has spawned much experimental effort as well as exotic theoretical mechanisms, thus far without a clear explanation. On page 627 of this issue, Pattie et al. (1) present the most precise measurement of the neutron lifetime to date. A new method of measuring trapped neutrons in situ allows a more detailed exploration of one of the more pernicious systematic effects in neutron traps, neutron phase-space evolution (the changing orbits of neutrons in the trap), than do previous methods. The precision achieved, combined with a very different set of systematic uncertainties, gives hope that experiments such as this one can help resolve the current situation with the neutron lifetime.

Suicidal behaviors in adolescents with ADHD: associations with depressive and other comorbidity, parent-child conflict, trauma exposure, and impairment.

PubMed

Daviss, W Burleson; Diler, Rasim S

2014-11-01

To examine potential predictors of lifetime suicidal behaviors (SBs) in adolescents with ADHD. Participants were 101 adolescents with ADHD aged 11 to 18 years, evaluated for lifetime SB and psychopathology with semistructured interviews, and for lifetime trauma exposure, parent-child conflict, ADHD symptoms, and functional impairment with child, parent, and teacher ratings. Controlling for the effects of age, female sex, and comorbid depressive and other disorders, lifetime SB (n = 28) remained significantly associated (p = .001) with parent-child conflict, and to a lesser extent (p < .05) with impairment in nonacademic domains of function and breadth of exposure to victimization events. Measures related to past and current ADHD symptoms and signs were not associated with lifetime SB. Apart from depression, clinicians should pay particular attention to parent-child conflict, victimization trauma, and social impairment rather than levels of ADHD symptoms when weighing the likelihood of SB in youth with ADHD. © 2012 SAGE Publications.

SIRTF thermal design modifications to increase lifetime

NASA Astrophysics Data System (ADS)

Petrick, S. W.

1993-01-01

An effort was made to increase the predicted lifetime of the SIRTF dewar by lowering the exterior shell temperature, increasing the radiated energy from the vapor cooled shields and reconfiguring the vapor cooled shields. The lifetime increases can be used to increase the scientific return from the mission and as a trade-off against mass and cost. This paper describes the configurations studied, the steady state thermal model used, the analytical methods and the results of the analysis. Much of the heat input to the outside dewar shell is radiative heat transfer from the solar panel. To lower the shell temperature, radiative cooled shields were placed between the solar panel and the dewar shell and between the bus and the dewar shell. Analysis showed that placing a radiator on the outer vapor cooled shield had a significant effect on lifetime. Lengthening the distance between the outer shell and the point where the vapor cooled shields are attached to the support straps also improved lifetime.

Stochastic gain in finite populations

NASA Astrophysics Data System (ADS)

Röhl, Torsten; Traulsen, Arne; Claussen, Jens Christian; Schuster, Heinz Georg

2008-08-01

Flexible learning rates can lead to increased payoffs under the influence of noise. In a previous paper [Traulsen , Phys. Rev. Lett. 93, 028701 (2004)], we have demonstrated this effect based on a replicator dynamics model which is subject to external noise. Here, we utilize recent advances on finite population dynamics and their connection to the replicator equation to extend our findings and demonstrate the stochastic gain effect in finite population systems. Finite population dynamics is inherently stochastic, depending on the population size and the intensity of selection, which measures the balance between the deterministic and the stochastic parts of the dynamics. This internal noise can be exploited by a population using an appropriate microscopic update process, even if learning rates are constant.

Relative influence of meteorological conditions and aerosols on the lifetime of mesoscale convective systems

PubMed Central

Chakraborty, Sudip; Fu, Rong; Massie, Steven T.; Stephens, Graeme

2016-01-01

Using collocated measurements from geostationary and polar-orbital satellites over tropical continents, we provide a large-scale statistical assessment of the relative influence of aerosols and meteorological conditions on the lifetime of mesoscale convective systems (MCSs). Our results show that MCSs’ lifetime increases by 3–24 h when vertical wind shear (VWS) and convective available potential energy (CAPE) are moderate to high and ambient aerosol optical depth (AOD) increases by 1 SD (1σ). However, this influence is not as strong as that of CAPE, relative humidity, and VWS, which increase MCSs’ lifetime by 3–30 h, 3–27 h, and 3–30 h per 1σ of these variables and explain up to 36%, 45%, and 34%, respectively, of the variance of the MCSs’ lifetime. AOD explains up to 24% of the total variance of MCSs’ lifetime during the decay phase. This result is physically consistent with that of the variation of the MCSs’ ice water content (IWC) with aerosols, which accounts for 35% and 27% of the total variance of the IWC in convective cores and anvil, respectively, during the decay phase. The effect of aerosols on MCSs’ lifetime varies between different continents. AOD appears to explain up to 20–22% of the total variance of MCSs’ lifetime over equatorial South America compared with 8% over equatorial Africa. Aerosols over the Indian Ocean can explain 20% of total variance of MCSs’ lifetime over South Asia because such MCSs form and develop over the ocean. These regional differences of aerosol impacts may be linked to different meteorological conditions. PMID:27313203

Relative influence of meteorological conditions and aerosols on the lifetime of mesoscale convective systems

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

Chakraborty, Sudip; Fu, Rong; Massie, Steven T.

Using collocated measurements from geostationary and polar-orbital satellites over tropical continents, in this paper we provide a large-scale statistical assessment of the relative influence of aerosols and meteorological conditions on the lifetime of mesoscale convective systems (MCSs). Our results show that MCSs’ lifetime increases by 3–24 h when vertical wind shear (VWS) and convective available potential energy (CAPE) are moderate to high and ambient aerosol optical depth (AOD) increases by 1 SD (1σ). However, this influence is not as strong as that of CAPE, relative humidity, and VWS, which increase MCSs’ lifetime by 3–30 h, 3–27 h, and 3–30 hmore » per 1σ of these variables and explain up to 36%, 45%, and 34%, respectively, of the variance of the MCSs’ lifetime. AOD explains up to 24% of the total variance of MCSs’ lifetime during the decay phase. This result is physically consistent with that of the variation of the MCSs’ ice water content (IWC) with aerosols, which accounts for 35% and 27% of the total variance of the IWC in convective cores and anvil, respectively, during the decay phase. The effect of aerosols on MCSs’ lifetime varies between different continents. AOD appears to explain up to 20–22% of the total variance of MCSs’ lifetime over equatorial South America compared with 8% over equatorial Africa. Aerosols over the Indian Ocean can explain 20% of total variance of MCSs’ lifetime over South Asia because such MCSs form and develop over the ocean. Finally, these regional differences of aerosol impacts may be linked to different meteorological conditions.« less

Relative influence of meteorological conditions and aerosols on the lifetime of mesoscale convective systems

DOE PAGES

Chakraborty, Sudip; Fu, Rong; Massie, Steven T.; ...

2016-06-16

Using collocated measurements from geostationary and polar-orbital satellites over tropical continents, in this paper we provide a large-scale statistical assessment of the relative influence of aerosols and meteorological conditions on the lifetime of mesoscale convective systems (MCSs). Our results show that MCSs’ lifetime increases by 3–24 h when vertical wind shear (VWS) and convective available potential energy (CAPE) are moderate to high and ambient aerosol optical depth (AOD) increases by 1 SD (1σ). However, this influence is not as strong as that of CAPE, relative humidity, and VWS, which increase MCSs’ lifetime by 3–30 h, 3–27 h, and 3–30 hmore » per 1σ of these variables and explain up to 36%, 45%, and 34%, respectively, of the variance of the MCSs’ lifetime. AOD explains up to 24% of the total variance of MCSs’ lifetime during the decay phase. This result is physically consistent with that of the variation of the MCSs’ ice water content (IWC) with aerosols, which accounts for 35% and 27% of the total variance of the IWC in convective cores and anvil, respectively, during the decay phase. The effect of aerosols on MCSs’ lifetime varies between different continents. AOD appears to explain up to 20–22% of the total variance of MCSs’ lifetime over equatorial South America compared with 8% over equatorial Africa. Aerosols over the Indian Ocean can explain 20% of total variance of MCSs’ lifetime over South Asia because such MCSs form and develop over the ocean. Finally, these regional differences of aerosol impacts may be linked to different meteorological conditions.« less

Search of collectivity at N >= 52 via lifetime measurements in ^96-98Ru

NASA Astrophysics Data System (ADS)

Kharraja, B.; Garg, U.; Ghugre, S. S.; Frohlich, A.; Ahmad, I.; Amro, H.; Blumenthal, D.; Carpenter, M. P.; Crowell, B.; Fisher, S.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Nissius, D.; Reviol, W.; Mueller, W.; Govil, I. M.; Ma, W. C.; Kaczarowski, R.; Ruchowska, E.

1996-05-01

Level structures of nuclei with N ~ 50 and Z ~ 40 exhibit interesting interplay between the single particle and collective degrees of freedom. Lifetime measurements are crucial to ascertain the intrinsic structures of the observed level sequences in this region and, specificaly to verify the onset of collectivity. This motivated us to undertake lifetime measurements using the RDM technique for ^96-98Ru nuclei. These nuclei were populated via the ^65Cu(^36Si,pyn) reaction at 142 MeV, and the Argonne-Notre Dame γ-ray facility was employed in conjonction with the Notre Dame plunger. Data were connected in coincidence at 12 distances rangin from 10 μm to 1000 μm giving us an effective lifetime range 1 ps to 400 ps.

Time-resolved laser spectroscopy of multiply ionized atoms: natural radiative lifetimes in Ce IV.

PubMed

Zhang, Z G; Svanberg, S; Quinet, P; Palmeri, P; Biémont, E

2001-12-31

Radiative lifetimes have been measured for two excited levels of Ce IV using the time-resolved laser-induced fluorescence technique. Ce3+ ions were produced in a laser-induced plasma. In the measurements, a suitable magnetic field was applied to reduce the recombination between electrons and the ions and thus the background light from the recombination, and special care was exercised to avoid flight-out-of-view effects on the lifetime measurements for the high-velocity ions. The experimental lifetime results, tau = 30(2) ns for the level 49 737 cm(-1) and tau = 30(3) ns for the level 52 226 cm(-1), were compared with relativistic Hartree-Fock calculations (tau = 30.5 and 30.0 ns) indicating a particularly excellent agreement.

Effects of ligand binding on the conformation and internal dynamics in specific regions of porcine pancreatic phospholipase A2 with tryptophan as a probe: a study combining time-resolved fluorescence spectroscopy and site-directed mutagenesis (same as p. 100)

NASA Astrophysics Data System (ADS)

Kuipers, Oscar; Vincent, Michel; Brochon, Jean-Claude; Verheij, Bert; de Haas, Gerard; Gallay, Jacques

1990-05-01

Exploration of the effect of ligand-protein interactions on conformational substates and internal dynamics in different regions of phospholipase A2 from porcine pancreas (PLA2), was performed by combining site-directed mutagenesis and time-resolved fluorescence measurements. The single tryptophan residue (Trp-3) in the wild type protein was replaced by a phenylalanine residue, whereafter Trp was substituted either for leucine-31 ,located in the calcium binding loop, or for phenylalanine-94, located at the "back side" of the enzyme, in a-helix E (Dijkstra et al., J. Mol. Biol., 147, 97-123, 1981). Analyses by the Maximum Entropy Method (MIEM) of the total fluorescence intensity decays, provide in each case a distribution of separate lifetime classes, which can be interpreted as reflecting the existence of discrete conformational substates in slow exchange with respect to the time-scale of the decay kinetics. The fluorescence decay of the W94 mutant is dominated by an extremely short excited state lifetime of ~60 ps, probably arising from the presence of two proximate disulfide bridges. Time-resolved fluorescence anisotropy studies show that the Trp residue near the NH2 terminus (Trp-3) undergoes a more limited rotational motion than the Trp-3 1 located in the calcium binding loop. The widest angular rotation is observed at position 94, in a-helix E. Calcium binding displays the strongest influence on the lifetime distribution of Trp-31: a major local conformation corresponding to a lifetime class with a barycenter value of ~5.5 ns and contributing to ~50% of the decay is selected. The conformations giving rise to the short lifetimes ((tau)1 and (tau)2 lifetime classes) become less important. The contribution of the third lifetime class (c3) stays at a constant value of 30%. In the presence of calcium, the amplitude of motion is wider than without the ion. There is virtually no effect of calcium binding on the lifetime distribution of the Trp residue at the 3 or the 94 position. Binding of the monomeric substrate analog n-dodecylphosphocholine (C12PN) in the presence of calcium hardly affects neither the Trp-3 excited state population distribution, nor its rotational dynamics. The binding of C12PN monomers to the W31 mutant further increases the contribution of the t4lifetime class at the expense of c2. A more restricted rotation of the Trp-31 residue is also induced. The binding of the micellar substrate analog n-hexadecylphosphocholine (C16PN) in the presence of calcium is very efficient in modifying the lifetime distribution of Trp-3. Essentially, one major broad lifetime population (centered at ~2.6 ns) is revealed by MEM analysis of the total intensity decay. The internal motion is slowed down and the angle of rotation is much smaller in this conformation. Neither the excited state lifetime distribution of Trp-31 nor its dynamics are affected by micelle binding relative to monomer binding. In conclusion, by placing a single Tip-residue at strategic positions along the peptide chain of PLA2, relevant to the binding of biological ligands, an excellent model system for the study of selective perturbations of conformational substates and internal dynamics is provided.

Effects of ligand binding on the conformation and internal dynamics in specific regions of porcine pancreatic phospholipase A2 with tryptophan as a probe: a study combinging time-resolved fluorescence spectroscopy and site-directed mutagenesis (same as p. 628)

NASA Astrophysics Data System (ADS)

Kuipers, Oscar; Vincent, Michel; Brochon, Jean-Claude; Verheij, Bert; de Haas, Gerard; Gallay, Jacques

1990-05-01

Exploration of the effect of ligand-protein interactions on conformational substates and internal dynamics in different regions of phospholipase A2 from porcine pancreas (PLA2), was performed by combining site-directed mutagenesis and time-resolved fluorescence measurements. The single tryptophan residue (Trp-3) in the wild type protein was replaced by a phenylalanine residue, whereafter Tip was substituted either for leucine-3 1 ,located in the calcium binding ioop, or for phenylalanine-94, located at the "back side" of the enzyme, in a-helix E (Dijkstra et al., J. Mol. Biol., 147, 97-123, 1981). Analyses by the Maximum Entropy Method (MEM) of the total fluorescence intensity decays, provide in each case a distribution of separate lifetime classes, which can be interpreted as reflecting the existence of discrete conformational substates in slow exchange with respect to the time-scale of the decay kinetics. The fluorescence decay of the W94 mutant is. dominated by an extremely short excited state lifetime of ~60 ps, probably arising from the presence of two proximate disulfide bridges. Time-resolved fluorescence anisotropy studies show that the Trp residue near the NH2 terminus (Trp-3) undergoes a more limited rotational motion than the Trp-3 1 located in the calcium binding loop. The widest angular rotation is observed at position 94, in a-helix E. Calcium binding displays the strongest influence on the lifetime distribution of Trp-3 1: a major local conformation corresponding to a lifetime class with a barycenter value of -5.5 ns and contributing to ~50% of the decay is selected. The conformations giving rise to the short lifetimes (τ1 and τ2 lifetime classes) become less important. The contribution of the third lifetime class (c3) stays at a constant value of 30%. In the presence of calcium, the amplitude of motion is wider than without the ion. There is virtually no effect of calcium binding on the lifetime distribution of the Trp residue at the 3 or the 94 position. Binding of the monomeric substrate analog n-dodecylphosphocholine (C12PN) in the presence of calcium hardly affects neither the Trp-3 excited state population distribution, nor its rotational dynamics. The binding of C12PN monomers to the W31 mutant further increases the contribution of the τ4 lifetime class at the expense of c2. A more restricted rotation of the Trp-3 1 residue is also induced. The binding of the micellar substrate analog n-hexadecylphosphocholine (C16PN) in the presence of calcium is very efficient in modifying the lifetime distribution of Trp-3. Essentially, one major broad lifetime population (centered at ~2.6 ns) is revealed by MEM analysis of the total intensity decay. The internal motion is slowed down and the angle of rotation is much smaller in this conformation. Neither the excited state lifetime distribution of Trp-31 nor its dynamics are affected by micelle binding relative to monomer binding. In conclusion, by placing a single Tip-residue at strategic positions along the peptide chain of PLA2, relevant to the binding of biological ligands, an excellent model system for the study of selective perturbations of conformational substates and internal dynamics is provided.

Lifetime trauma, personality traits, and health: A pathway to midlife health status.

PubMed

Hampson, Sarah E; Edmonds, Grant W; Goldberg, Lewis R; Barckley, Maureen; Klest, Bridget; Dubanoski, Joan P; Hillier, Teresa A

2016-07-01

This study investigated whether lifetime experience of trauma is related to personality through instrumental and reactive trait processes, and whether lifetime trauma is a mechanism underlying the association between childhood conscientiousness and objectively assessed adult physical health. Participants (N = 831) were 442 women and 389 men from the Hawaii longitudinal study of personality and health. Teacher assessments of personality were obtained when the participants were in elementary school. Self-reported adult personality assessments, lifetime histories of trauma experience, and objectively assessed physiological dysregulation were obtained between ages 45-55. Women tended to report more high-betrayal trauma than men, whereas men reported more low-betrayal trauma than women. Women who were judged by their teachers to be less agreeable and less conscientious in childhood reported more lifetime trauma, suggesting instrumental trait processes. For both genders, neuroticism and openness/intellect/imagination in adulthood, but not in childhood, were associated with lifetime trauma, suggesting reactive trait processes. For both genders, trauma experience was correlated with dysregulation and with Body Mass Index (BMI). The indirect paths from childhood conscientiousness to adult dysregulation and BMI through total teen and adult trauma were significant for women, but not for men (indirect effect for women's dysregulation = -.025, p = .040, 95% confidence interval [CI] = -.048, -.001; indirect effect for women's BMI = -.037, p = .009, 95% CI = -.067, -.008). Teen and adult trauma experience appears to be a hitherto unidentified mechanism in women underlying the association between conscientiousness and health. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

A Cohort Effect of the Sexual Revolution May Be Masking an Increase in Human Papillomavirus Detection at Menopause in the United States

PubMed Central

Gravitt, Patti E.; Rositch, Anne F.; Silver, Michelle I.; Marks, Morgan A.; Chang, Kathryn; Burke, Anne E.; Viscidi, Raphael P.

2013-01-01

Background. Cohort effects, new sex partnerships, and human papillomavirus (HPV) reactivation have been posited as explanations for the bimodal age-specific HPV prevalence observed in some populations; no studies have systematically evaluated the reasons for the lack of a second peak in the United States. Methods. A cohort of 843 women aged 35–60 years were enrolled into a 2-year, semiannual follow-up study. Age-specific HPV prevalence was estimated in strata defined by a lower risk of prior infection (<5 self-reported lifetime sex partners) and a higher risk of prior infection (≥5 lifetime sex partners). The interaction between age and lifetime sex partners was tested using likelihood ratio statistics. Population attributable risk (PAR) was estimated using Levin's formula. Results. The age-specific prevalence of 14 high-risk HPV genotypes (HR-HPV) declined with age among women with <5 lifetime sex partners but not among women with ≥5 lifetime sex partners (P = .01 for interaction). The PAR for HR-HPV due to ≥5 lifetime sex partners was higher among older women (87.2%), compared with younger women (28.0%). In contrast, the PAR associated with a new sex partner was 28% among women aged 35–49 years and 7.7% among women aged 50–60 years. Conclusions. A lower cumulative probability of HPV infection among women with a sexual debut before the sexual revolution may be masking an age-related increase in HPV reactivation in the United States. PMID:23242540

Lifetime Trauma, Personality Traits, and Health: A Pathway to Midlife Health Status

PubMed Central

Hampson, Sarah E.; Edmonds, Grant W.; Goldberg, Lewis R.; Barckley, Maureen; Klest, Bridget; Dubanoski, Joan P.; Hillier, Teresa A.

2016-01-01

Objective This study investigated whether lifetime experience of trauma is related to personality through instrumental and reactive trait processes, and whether lifetime trauma is a mechanism underlying the association between childhood conscientiousness and objectively assessed adult physical health. Method Participants (N = 831) were 442 women and 389 men from the Hawaii longitudinal study of personality and health. Teacher assessments of personality were obtained when the participants were in elementary school. Self-reported adult personality assessments, lifetime histories of trauma experience, and objectively assessed physiological dysregulation were obtained between ages 45–55. Results Women tended to report more high-betrayal trauma than men, whereas men reported more low-betrayal trauma than women. Women who were judged by their teachers to be less agreeable and less conscientious in childhood reported more lifetime trauma, suggesting instrumental trait processes. For both genders, neuroticism and openness/intellect/imagination in adulthood, but not in childhood, were associated with lifetime trauma, suggesting reactive trait processes. For both genders, trauma experience was correlated with dysregulation and with BMI. The indirect paths from childhood conscientiousness to adult dysregulation and BMI through total teen and adult trauma were significant for women, but not for men (indirect effect for women’s dysregulation = −.025, p = .040, 95% CI = −.048, −.001; indirect effect for women’s BMI = −.037, p = .009, 95% CI = −.067, −.008). Conclusion Teen and adult trauma experience appears to be a hitherto unidentified mechanism in women underlying the association between conscientiousness and health. PMID:27100170

Heat transfer model and finite element formulation for simulation of selective laser melting

NASA Astrophysics Data System (ADS)

Roy, Souvik; Juha, Mario; Shephard, Mark S.; Maniatty, Antoinette M.

2017-10-01

A novel approach and finite element formulation for modeling the melting, consolidation, and re-solidification process that occurs in selective laser melting additive manufacturing is presented. Two state variables are introduced to track the phase (melt/solid) and the degree of consolidation (powder/fully dense). The effect of the consolidation on the absorption of the laser energy into the material as it transforms from a porous powder to a dense melt is considered. A Lagrangian finite element formulation, which solves the governing equations on the unconsolidated reference configuration is derived, which naturally considers the effect of the changing geometry as the powder melts without needing to update the simulation domain. The finite element model is implemented into a general-purpose parallel finite element solver. Results are presented comparing to experimental results in the literature for a single laser track with good agreement. Predictions for a spiral laser pattern are also shown.

A New Finite-Conductivity Droplet Evaporation Model Including Liquid Turbulence Effect

NASA Technical Reports Server (NTRS)

Balasubramanyam, M. S.; Chen, C. P.; Trinh, H. P.

2006-01-01

A new approach to account for finite thermal conductivity and turbulence effects within atomizing droplets of an evaporating spray is presented in this paper. The model is an extension of the T-blob and T-TAB atomization/spray model of Trinh and Chen [9]. This finite conductivity model is based on the two-temperature film theory in which the turbulence characteristics of the droplet are used to estimate the effective thermal diffusivity for the liquid-side film thickness. Both one-way and two-way coupled calculations were performed to investigate the performance cf this model against the published experimental data.

Cumulative Effects of Multiple Forms of Violence and Abuse on Women.

PubMed

MacIntosh, Judith; Wuest, Judith; Ford-Gilboe, Marilyn; Varcoe, Colleen

2015-01-01

Little is known about how patterns of workplace bullying contribute to the negative effects of lifetime violence. Analysis of longitudinal data from a study of women's health after separating from an abusive partner revealed that 76% of 229 women had experienced workplace bullying. Workplace bullying was associated with child sexual abuse, adult sexual assault, and ongoing partner abuse. Timing was critical, with those experiencing past workplace bullying having poorer health and fewer personal and social resources than those experiencing none, ongoing, or past and ongoing bullying. Lifetime sexual harassment (54%) was associated with higher posttraumatic stress disorder symptomology and greater likelihood of leaving workplaces and physical bullying (16%) with poorer health and personal, social, and economic resources. These findings highlight the importance of including bullying in studying lifetime violence.

Thermal imaging of high power diode lasers subject to back-irradiance

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

Li, C.; Pipe, K. P.; Cao, C.

In this study, CCD-based thermoreflectance imaging and finite element modeling are used to study the two-dimensional (2D) temperature profile of a junction-down broad-area diode laser facet subject to back-irradiance. By determining the temperature rise in the active region (ΔΤAR) at different diode laser optical powers, back-irradiance reflectance levels, and back-irradiance spot locations, we find that ΔΤAR increases by nearly a factor of three when the back-irradiance spot is centered in the absorbing substrate approximately 5 μm away from the active region, a distance roughly equal to half of the back-irradiance spot FWHM (9 μm). This corroborates prior work studying themore » relationship between the back-irradiance spot location and catastrophic optical damage, suggesting a strong thermal basis for reduced laser lifetime in the presence of back-irradiance for diode lasers fabricated on absorbing substrates.« less

Revised and extended level scheme of the doubly-odd nucleus {sup 188}Ir

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

Jungclaus, A.; Modamio, V.; Egido, J. L.

2008-02-15

High-spin states in the doubly odd Z=77 nucleus {sup 188}Ir were studied using the reaction {sup 186}W({sup 7}Li, 5n) at 59 MeV and the GASP spectrometer for {gamma}-ray detection. The level structures recently suggested to be built on the known 4.1(3) ms isomeric state of this nucleus have been considerably revised and extended and an isomer with a lifetime of 17.7(2) ns has been identified within the main decay sequence. In addition two rotational bands built on low spin states below the ms isomer have been observed for the first time. The basic features of the excitation scheme of {supmore » 188}Ir are discussed within the Hartree-Fock-Bogoliubov theory within the Lipkin-Nogami approach with the finite-range density-dependent Gogny force.« less

Plasmonic platforms of self-assembled silver nanostructures in application to fluorescence

PubMed Central

Luchowski, Rafal; Calander, Nils; Shtoyko, Tanya; Apicella, Elisa; Borejdo, Julian; Gryczynski, Zygmunt; Gryczynski, Ignacy

2011-01-01

Fluorescence intensity changes were investigated theoretically and experimentally using self-assembled colloidal structures on silver semitransparent mirrors. Using a simplified quasi-static model and finite element method, we demonstrate that near-field interactions of metallic nanostructures with a continuous metallic surface create conditions that produce enormously enhanced surface plasmon resonances. The results were used to explain the observed enhancements and determine the optimal conditions for the experiment. The theoretical parts of the studies are supported with reports on detailed emission intensity changes which provided multiple fluorescence hot spots with 2–3 orders of enhancements. We study two kinds of the fluorophores: dye molecules and fluorescent nanospheres characterized with similar spectral emission regions. Using a lifetime-resolved fluorescence/reflection confocal microscopy technique, we find that the largest rate for enhancement (~1000-fold) comes from localized areas of silver nanostructures. PMID:21403765

Thermal imaging of high power diode lasers subject to back-irradiance

DOE PAGES

Li, C.; Pipe, K. P.; Cao, C.; ...

2018-03-07

In this study, CCD-based thermoreflectance imaging and finite element modeling are used to study the two-dimensional (2D) temperature profile of a junction-down broad-area diode laser facet subject to back-irradiance. By determining the temperature rise in the active region (ΔΤAR) at different diode laser optical powers, back-irradiance reflectance levels, and back-irradiance spot locations, we find that ΔΤAR increases by nearly a factor of three when the back-irradiance spot is centered in the absorbing substrate approximately 5 μm away from the active region, a distance roughly equal to half of the back-irradiance spot FWHM (9 μm). This corroborates prior work studying themore » relationship between the back-irradiance spot location and catastrophic optical damage, suggesting a strong thermal basis for reduced laser lifetime in the presence of back-irradiance for diode lasers fabricated on absorbing substrates.« less

Extending Quantum Chemistry of Bound States to Electronic Resonances

NASA Astrophysics Data System (ADS)

Jagau, Thomas-C.; Bravaya, Ksenia B.; Krylov, Anna I.

2017-05-01

Electronic resonances are metastable states with finite lifetime embedded in the ionization or detachment continuum. They are ubiquitous in chemistry, physics, and biology. Resonances play a central role in processes as diverse as DNA radiolysis, plasmonic catalysis, and attosecond spectroscopy. This review describes novel equation-of-motion coupled-cluster (EOM-CC) methods designed to treat resonances and bound states on an equal footing. Built on complex-variable techniques such as complex scaling and complex absorbing potentials that allow resonances to be associated with a single eigenstate of the molecular Hamiltonian rather than several continuum eigenstates, these methods extend electronic-structure tools developed for bound states to electronic resonances. Selected examples emphasize the formal advantages as well as the numerical accuracy of EOM-CC in the treatment of electronic resonances. Connections to experimental observables such as spectra and cross sections, as well as practical aspects of implementing complex-valued approaches, are also discussed.

Steady-state currents in p-n junction filaments or grains in case of large surface recombination velocities at lateral surfaces

NASA Technical Reports Server (NTRS)

Von Roos, O.; Lindholm, F. A.

1985-01-01

Recently it has been pointed out that the saturation current of a semiconductor filament which constitutes part of a p-n junction diverges when the surface recombination velocity at the faces become infinitely large. Here it is pointed out that this is to be expected on physical grounds since, whenever the carrier concentration is kept off equilibrium by an outside agent, and at the same time recombination lifetimes in the bulk or in surface layers tend to zero, concentration gradients tend to infinity. As also previously noted, the situation can be remedied by using realistic (finite) surface recombination velocities in model calculations. However, this procedure leads to mathematical complexities which have been circumvented recently by the introduction of a heuristic approach. It is the aim of this paper to assess the validity of the heuristic approach by means of detailed and exact calculations.

Performance and Reliability of Bonded Interfaces for High-Temperature Packaging

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

Paret, Paul P

2017-08-02

Sintered silver has proven to be a promising candidate for use as a die-attach and substrate-attach material in automotive power electronics components. It holds promise of greater reliability than lead-based and lead-free solders, especially at higher temperatures (>200 degrees C). Accurate predictive lifetime models of sintered silver need to be developed and its failure mechanisms thoroughly characterized before it can be deployed as a die-attach or substrate-attach material in wide-bandgap device-based packages. Mechanical characterization tests that result in stress-strain curves and accelerated tests that produce cycles-to-failure result will be conducted. Also, we present a finite element method (FEM) modeling methodologymore » that can offer greater accuracy in predicting the failure of sintered silver under accelerated thermal cycling. A fracture mechanics-based approach is adopted in the FEM model, and J-integral/thermal cycle values are computed.« less

Nondestructive Characterization Techniques Used for Ceramic Matrix Composite Life Determination

NASA Technical Reports Server (NTRS)

Effinger, Michael; Koenig, John; Ellingson, Bill; Spohnholtz, Todd

2000-01-01

Recent results indicate that the specific damping capacity and resonant frequency measurements taken periodically during a component's lifetime is able to quantify the mechanical fatigue of CMCS. This gives hope for the potential of determining the actual and residual life of CMC materials using a combination of nondestructive techniques. If successful, then this new paradigm for life prediction of CMCs could revolutionize the approach for designing and servicing CMC components, thereby significantly reducing costs for design, development, health monitoring, and maintenance of CMC components and systems. The Nondestructive Characterization (NDC) life prediction approach would complement life prediction using micromechanics and continuum finite element models. This paper reports on the initial concept of NDC life prediction, a review of the C/SiC blisk damping data, and how changes in the specific damping capacity & ultrasonic elastic modulus data have established the concept as a possibility.

Launch Window Trade Analysis for the James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Yu, Wayne H.; Richon, Karen

2014-01-01

The James Webb Space Telescope (JWST) is a large-scale space telescope mission designed to study fundamental astrophysical questions ranging from the formation of the universe to the origin of planetary systems and the origins of life. JWSTs orbit design is a Libration Point Orbit (LPO) around the Sun-Earth/Moon (SEM) L2 point for a planned mission lifetime of 10.5 years. The launch readiness period for JWST is from Oct 1st, 2018 November 30th, 2018. This paper presents the first launch window analysis for the JWST observatory using finite-burn modeling; previous analysis assumed a single impulsive midcourse correction to achieve the mission orbit. The physical limitations of the JWST hardware stemming primarily from propulsion, communication and thermal requirements alongside updated mission design requirements result in significant launch window within the launch readiness period. Future plans are also discussed.

Schwinger mechanism with energy dissipation in ``glasma''

NASA Astrophysics Data System (ADS)

Iwazaki, Aiichi

2011-12-01

Initial states of “glasma” in high-energy heavy-ion collisions are longitudinal classical color electric and magnetic fields. Assuming finite color electric conductivity, we show that the color electric field decays by quark pair production with the lifetime of the order of Qs-1, i.e., the inverse of the saturation momentum. Quarks and antiquarks created in the pair production are immediately thermalized as long as their temperature β-1 is lower than Qs. Namely, the relaxation time of the quarks to be thermalized is much shorter than Qs-1 when β-1≪Qs. We also show that the quarks acquire longitudinal momentum of the order of Qs by the acceleration of the electric field. To discuss the quark pair production, we use chiral anomaly, which has been shown to be a very powerful tool in the presence of strong magnetic field.

James Webb Space Telescope Launch Window Trade Analysis

NASA Technical Reports Server (NTRS)

Yu, Wayne; Richon, Karen

2014-01-01

The James Webb Space Telescope (JWST) is a large-scale space telescope mission designed to study fundamental astrophysical questions ranging from the formation of the universe to the origin of planetary systems and the origins of life. JWSTs orbit design is a Libration Point Orbit (LPO) around the Sun-EarthMoon (SEM) L2 point for a planned mission lifetime of 10.5 years. The launch readiness period for JWST is from Oct 1st, 2018 November 30th, 2018. This paper presents the first launch window analysis for the JWST observatory using finite-burn modeling; previous analysis assumed a single impulsive midcourse correction to achieve the mission orbit. The physical limitations of the JWST hardware stemming primarily from propulsion, communication and thermal requirements alongside updated mission design requirements result in significant launch window within the launch readiness period. Future plans are also discussed.

Thermal imaging of high power diode lasers subject to back-irradiance

NASA Astrophysics Data System (ADS)

Li, C.; Pipe, K. P.; Cao, C.; Thiagarajan, P.; Deri, R. J.; Leisher, P. O.

2018-03-01

CCD-based thermoreflectance imaging and finite element modeling are used to study the two-dimensional (2D) temperature profile of a junction-down broad-area diode laser facet subject to back-irradiance. By determining the temperature rise in the active region (ΔΤAR) at different diode laser optical powers, back-irradiance reflectance levels, and back-irradiance spot locations, we find that ΔΤAR increases by nearly a factor of three when the back-irradiance spot is centered in the absorbing substrate approximately 5 μm away from the active region, a distance roughly equal to half of the back-irradiance spot FWHM (9 μm). This corroborates prior work studying the relationship between the back-irradiance spot location and catastrophic optical damage, suggesting a strong thermal basis for reduced laser lifetime in the presence of back-irradiance for diode lasers fabricated on absorbing substrates.

Optimized Finite Difference Method for the Full-Potential XANES Simulations: Application to Molecular Adsorption Geometries in MOFs and Metal-Ligand Intersystem Crossing Transients.

PubMed

Guda, Sergey A; Guda, Alexander A; Soldatov, Mikhail A; Lomachenko, Kirill A; Bugaev, Aram L; Lamberti, Carlo; Gawelda, Wojciech; Bressler, Christian; Smolentsev, Grigory; Soldatov, Alexander V; Joly, Yves

2015-09-08

Accurate modeling of the X-ray absorption near-edge spectra (XANES) is required to unravel the local structure of metal sites in complex systems and their structural changes upon chemical or light stimuli. Two relevant examples are reported here concerning the following: (i) the effect of molecular adsorption on 3d metals hosted inside metal-organic frameworks and (ii) light induced dynamics of spin crossover in metal-organic complexes. In both cases, the amount of structural models for simulation can reach a hundred, depending on the number of structural parameters. Thus, the choice of an accurate but computationally demanding finite difference method for the ab initio X-ray absorption simulations severely restricts the range of molecular systems that can be analyzed by personal computers. Employing the FDMNES code [Phys. Rev. B, 2001, 63, 125120] we show that this problem can be handled if a proper diagonalization scheme is applied. Due to the use of dedicated solvers for sparse matrices, the calculation time was reduced by more than 1 order of magnitude compared to the standard Gaussian method, while the amount of required RAM was halved. Ni K-edge XANES simulations performed by the accelerated version of the code allowed analyzing the coordination geometry of CO and NO on the Ni active sites in CPO-27-Ni MOF. The Ni-CO configuration was found to be linear, while Ni-NO was bent by almost 90°. Modeling of the Fe K-edge XANES of photoexcited aqueous [Fe(bpy)3](2+) with a 100 ps delay we identified the Fe-N distance elongation and bipyridine rotation upon transition from the initial low-spin to the final high-spin state. Subsequently, the X-ray absorption spectrum for the intermediate triplet state with expected 100 fs lifetime was theoretically predicted.

Finite-Size Effects of Binary Mutual Diffusion Coefficients from Molecular Dynamics

PubMed Central

2018-01-01

Molecular dynamics simulations were performed for the prediction of the finite-size effects of Maxwell-Stefan diffusion coefficients of molecular mixtures and a wide variety of binary Lennard–Jones systems. A strong dependency of computed diffusivities on the system size was observed. Computed diffusivities were found to increase with the number of molecules. We propose a correction for the extrapolation of Maxwell–Stefan diffusion coefficients to the thermodynamic limit, based on the study by Yeh and Hummer (J. Phys. Chem. B, 2004, 108, 15873−15879). The proposed correction is a function of the viscosity of the system, the size of the simulation box, and the thermodynamic factor, which is a measure for the nonideality of the mixture. Verification is carried out for more than 200 distinct binary Lennard–Jones systems, as well as 9 binary systems of methanol, water, ethanol, acetone, methylamine, and carbon tetrachloride. Significant deviations between finite-size Maxwell–Stefan diffusivities and the corresponding diffusivities at the thermodynamic limit were found for mixtures close to demixing. In these cases, the finite-size correction can be even larger than the simulated (finite-size) Maxwell–Stefan diffusivity. Our results show that considering these finite-size effects is crucial and that the suggested correction allows for reliable computations. PMID:29664633

Subjective Effect of September 11, 2001 among Pregnant Women: Is Cumulative History of Interpersonal Violence Important?

ERIC Educational Resources Information Center

Lewis, Marilyn W.; Cavanagh, Paul K.; Ahn, Grace; Yoshioka, Marianne R.

2008-01-01

Prior history of trauma may sensitize individuals to subsequent trauma, including terrorist attacks. Using a convenience sample of secondary, cross-sectional data, pregnant women were grouped based on lifetime interpersonal violence history. Cumulative risk theory was used to evaluate the association of lifetime interpersonal violence history and…

Lifetime Achievement Patterns, Retirement and Life Satisfaction of Gifted Aged Women.

ERIC Educational Resources Information Center

Holahan, Carole Kovalic

1981-01-01

Investigated the relationship of lifetime achievement patterns and retirement, to life satisfaction for gifted aging women (N=352). Results showed a significant interaction between marital status and work pattern on overall life satisfaction suggesting an additive negative effect of loss of spouse and a work history of working for income alone.…

Income Transfers and Assets of the Poor. Revised. Discussion Paper.

ERIC Educational Resources Information Center

Ziliak, James P.

Contrary to the predictions of the standard life-cycle model, many low lifetime-income households accumulate little wealth relative to their incomes compared to households with high lifetime income. This paper uses data from the Panel Study of Income Dynamics and a correlated random-effects generalized model of moments estimator to decompose the…

Mechanical degradation of fuel cell membranes under fatigue fracture tests

NASA Astrophysics Data System (ADS)

Khorasany, Ramin M. H.; Sadeghi Alavijeh, Alireza; Kjeang, Erik; Wang, G. G.; Rajapakse, R. K. N. D.

2015-01-01

The effects of cyclic stresses on the fatigue and mechanical stability of perfluorosulfonic acid (PFSA) membranes are experimentally investigated under standard fuel cell conditions. The experiments are conducted ex-situ by subjecting membrane specimens to cyclic uniaxial tension at controlled temperature and relative humidity. The fatigue lifetime is measured in terms of the number of cycles until ultimate fracture. The results indicate that the membrane fatigue lifetime is a strong function of the applied stress, temperature, and relative humidity. The fatigue life increases exponentially with reduced stresses in all cases. The effect of temperature is found to be more significant than that of humidity, with reduced fatigue life at high temperatures. The maximum membrane strain at fracture is determined to decrease exponentially with increasing membrane lifetime. At a given fatigue life, a membrane exposed to fuel cell conditions is shown to accommodate more plastic strain before fracture than one exposed to room conditions. Overall, the proposed ex-situ membrane fatigue experiment can be utilized to benchmark the fatigue lifetime of new materials in a fraction of the time and cost associated with conventional in-situ accelerated stress testing methods.

Comparative study of MYSat attitude stability effect on power generation and lifetime

NASA Astrophysics Data System (ADS)

Amilia Ismail, Norilmi; Thaheer, Ahmad Shaqeer Mohamed; Izmir Yamin, Mohd.

2018-05-01

Universiti Sains Malaysia Space System Lab (USSL) is currently developing a 1U cubesat named MYSat. The satellite mission is to measure electron-density in the Ionosphere E-Layer. Power generation from a solar panel is limited due to a small area of the satellite. Apart from that, the satellite is expecting to continuously spinning and tumbling throughout the mission lifetime as the satellite will be launched without an attitude control system. This paper compares the effect on power generation and the lifetime of MYSat of two conditions; first is with attitude controll where satellite pointing to nadir and later is uncontrol attitude of the satellite. The analysis has been conducted using Analytical Graphics, Inc. (AGI) Systems Tool Kit (STK) software. This study assumed the satellite used a hexagonal solar cell with a theoretical efficiency of 29% identical to an Ultra Triple-Junction (UTJ) solar cell. The simulation is done in one year duration on different attitude configuration. The worst-case condition, where the Earth is positioned at apogee, has been chosen for the comparative study and the lifetime of the satellite is also simulated and compared.

Finite micro-tab system for load control on a wind turbine

NASA Astrophysics Data System (ADS)

Bach, A. B.; Lennie, M.; Pechlivanoglou, G.; Nayeri, C. N.; Paschereit, C. O.

2014-06-01

Finite micro-tabs have been investigated experimentally to evaluate the potential for load control on wind turbines. Two dimensional full span, as well as multiple finite tabs of various aspect ratios have been studied on an AH93W174 airfoil at different chord wise positions. A force balance was used to measure the aerodynamic loads. Furthermore, the wake vortex system consisting of the Karman vortex street as well as the tab tip vortices was analyzed with a 12-hole probe and hot wire anemometry. Finally, conventional oil paint as well as a quantitative digital flow analysis technique called SMARTviz were used to visualize the flow around the finite tab configurations. Results have shown that the devices are an effective solution to alleviate the airfoils overall load. The influence of the tab height, tab position as well as the finite tab aspect ratio on the lift and lift to drag ratio have been evaluated. It could be shown, that the lift difference can either be varied by changing the tab height as well as by altering the aspect ratio of the finite tabs. The drag of a two-dimensional flap is directly associated with the vortex street, while in the case of the finite tab, the solidity ratio of the tabs has the strongest effect on the drag. Therefore, the application of a finite tab system showed to improve the lift to drag ratio.

Linear Array Ultrasonic Test Results from Alkali-Silica Reaction (ASR) Specimens

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

Clayton, Dwight A; Khazanovich, Dr. Lev; Salles, Lucio

2016-04-01

The purpose of the U.S. Department of Energy Office of Nuclear Energy’s Light Water Reactor Sustainability (LWRS) Program is to develop technologies and other solutions that can improve the reliability, sustain the safety, and extend the operating lifetimes of nuclear power plants (NPPs) beyond 60 years. Since many important safety structures in an NPP are constructed of concrete, inspection techniques must be developed and tested to evaluate the internal condition. In-service containment structures generally do not allow for the destructive measures necessary to validate the accuracy of these inspection techniques. This creates a need for comparative testing of the variousmore » nondestructive evaluation (NDE) measurement techniques on concrete specimens with known material properties, voids, internal microstructure flaws, and reinforcement locations.This report presents results of the ultrasound evaluation of four concrete slabs with varying levels of ASR damage present. This included an investigation of the experimental results, as well as a supplemental simulation considering the effect of ASR damage by elasto-dynamic wave propagation using a finite integration technique method. It was found that the Hilbert Transform Indicator (HTI), developed for quantification of freeze/thaw damage in concrete structures, could also be successfully utilized for quantification of ASR damage. internal microstructure flaws, and reinforcement locations.« less

Acoustic waves from mechanical impulses due to fluorescence resonant energy (Förster) transfer: Blowing a whistle with light

NASA Astrophysics Data System (ADS)

Zurita-Sánchez, J. R.; Henkel, C.

2012-02-01

We present a momentum transfer mechanism mediated by electromagnetic fields that originates in a system of two nearby molecules: one excited (donor D*) and the other in ground state (acceptor A). An intermolecular force related to fluorescence resonant energy or Förster transfer (FRET) arises in the unstable D*A molecular system, which differs from the equilibrium van der Waals interaction. Due to the its finite lifetime, a mechanical impulse is imparted to the relative motion in the system. We analyze the FRET impulse when the molecules are embedded in free space and find that its magnitude can be much greater than the single recoil photon momentum, getting comparable with the thermal momentum (Maxwell-Boltzmann distribution) at room temperature. In addition, we propose that this FRET impulse can be exploited in the generation of acoustic waves inside a film containing layers of donor and acceptor molecules, when a picosecond laser pulse excites the donors. This acoustic transient is distinguishable from that produced by thermal stress due to laser absorption, and may therefore play a role in photoacoustic spectroscopy. The effect can be seen as exciting a vibrating system like a string or organ pipe with light; it may be used as an opto-mechanical transducer.

Semiparametric methods to contrast gap time survival functions: Application to repeat kidney transplantation.

PubMed

Shu, Xu; Schaubel, Douglas E

2016-06-01

Times between successive events (i.e., gap times) are of great importance in survival analysis. Although many methods exist for estimating covariate effects on gap times, very few existing methods allow for comparisons between gap times themselves. Motivated by the comparison of primary and repeat transplantation, our interest is specifically in contrasting the gap time survival functions and their integration (restricted mean gap time). Two major challenges in gap time analysis are non-identifiability of the marginal distributions and the existence of dependent censoring (for all but the first gap time). We use Cox regression to estimate the (conditional) survival distributions of each gap time (given the previous gap times). Combining fitted survival functions based on those models, along with multiple imputation applied to censored gap times, we then contrast the first and second gap times with respect to average survival and restricted mean lifetime. Large-sample properties are derived, with simulation studies carried out to evaluate finite-sample performance. We apply the proposed methods to kidney transplant data obtained from a national organ transplant registry. Mean 10-year graft survival of the primary transplant is significantly greater than that of the repeat transplant, by 3.9 months (p=0.023), a result that may lack clinical importance. © 2015, The International Biometric Society.

Magnetic Frequency Response of HL-LHC Beam Screens

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

Morrone, M.; Martino, M.; De Maria, R.

Magnetic fields used to control particle beams in accelerators are usually controlled by regulating the electrical current of the power converters. In order to minimize lifetime degradation and ultimately luminosity loss in circular colliders, current-noise is a highly critical figure of merit of power converters, in particular for magnets located in areas with high beta-function, like the High Luminosity Large Hadron Collider (HL-LHC) insertions. However, what is directly acting upon the beam is the magnetic field and not the current of the power converter, which undergoes several frequency-dependent transformations until the desired magnetic field, seen by the beam, is obtained.more » Beam screens are very rarely considered when assessing or specifying the noise figure of merit, but their magnetic frequency response is such that they realize relatively effective low pass filtering of the magnetic field produced by the system magnet-power converter. This work aims at filling this gap by quantifying the expected impact of different beam screen layouts for the most relevant HL-LHC insertion magnets. A welldefined post-processing technique is used to derive the frequency response of the different multipoles from multi-physics Finite Element Method (FEM) simulation results. In addition, a well approximated analytical formula for the low-frequency range of multi-layered beam screens is presented.« less

Zonal Flows and Long-lived Axisymmetric Pressure Bumps in Magnetorotational Turbulence

NASA Astrophysics Data System (ADS)

Johansen, A.; Youdin, A.; Klahr, H.

2009-06-01

We study the behavior of magnetorotational turbulence in shearing box simulations with a radial and azimuthal extent up to 10 scale heights. Maxwell and Reynolds stresses are found to increase by more than a factor of 2 when increasing the box size beyond two scale heights in the radial direction. Further increase of the box size has little or no effect on the statistical properties of the turbulence. An inverse cascade excites magnetic field structures at the largest scales of the box. The corresponding 10% variation in the Maxwell stress launches a zonal flow of alternating sub- and super-Keplerian velocity. This, in turn, generates a banded density structure in geostrophic balance between pressure and Coriolis forces. We present a simplified model for the appearance of zonal flows, in which stochastic forcing by the magnetic tension on short timescales creates zonal flow structures with lifetimes of several tens of orbits. We experiment with various improved shearing box algorithms to reduce the numerical diffusivity introduced by the supersonic shear flow. While a standard finite difference advection scheme shows signs of a suppression of turbulent activity near the edges of the box, this problem is eliminated by a new method where the Keplerian shear advection is advanced in time by interpolation in Fourier space.

Hot spots based gold nanostar@SiO2@CdSe/ZnS quantum dots complex with strong fluorescence enhancement

NASA Astrophysics Data System (ADS)

Shan, Feng; Su, Dan; Li, Wei; Hu, Wei; Zhang, Tong

2018-02-01

In this paper, a novel gold nanostar (NS)@SiO2@CdSe/ZnS quantum dots (QDs) complex with plasmon-enhanced fluorescence synthesized using a step-by-step surface linkage method was presented. The gold NS was synthesized by the seed growth method. The synthesized gold NS with the apexes structure has a hot-spot effect due to the strong electric field distributed at its sharp apexes, which leads to a plasmon resonance enhancement. Because the distance between QDs and metal nanostructures can be precisely controlled by this method, the relationship between enhancement and distance was revealed. The thickness of SiO2 shell was also optimized and the optimum distance of about 21 nm was obtained. The highest fluorescence enhancement of 4.8-fold accompanied by a minimum fluorescence lifetime of 2.3 ns were achieved. This strong enhancement comes from the hot spots distributed at the sharp tip of our constructed nanostructure. Through the finite element method, we calculated the field distribution on the surface of NS and found that gold NS with the sharpest apexes exhibited the highest field enhancement, which matches well with our experiment result. This complex shows tremendous potential applications for liquid-dependent biometric imaging systems.

Chlorophyll fluorescence lifetime imaging provides new insight into the chlorosis induced by plant virus infection.

PubMed

Lei, Rong; Jiang, Hongshan; Hu, Fan; Yan, Jin; Zhu, Shuifang

2017-02-01

Leaf chlorosis induced by plant virus infection has a short fluorescence lifetime, which reflects damaged photosynthetic complexes and degraded chloroplasts. Plant viruses often induce chlorosis and necrosis, which are intimately related to photosynthetic functions. Chlorophyll fluorescence lifetime measurement is a valuable noninvasive tool for analyzing photosynthetic processes and is a sensitive indicator of the environment surrounding the fluorescent molecules. In this study, our central goal was to explore the effect of viral infection on photosynthesis by employing chlorophyll fluorescence lifetime imaging (FLIM), steady-state fluorescence, non-photochemical quenching (NPQ), transmission electron microscopy (TEM), and pigment analysis. The data indicated that the chlorophyll fluorescence lifetime of chlorotic leaves was significantly shorter than that of healthy control leaves, and the fitted short lifetime component of chlorophyll fluorescence of chlorotic leaves was dominant. This dominant short lifetime component may result from damage to the structure of thylakoid, which was confirmed by TEM. The NPQ value of chlorotic leaves was slightly higher than that of healthy green leaves, which can be explained by increased neoxanthin, lutein and violaxanthin content relative to chlorophyll a. The difference in NPQ is slight, but FLIM can provide simple and direct characterization of PSII structure and photosynthetic function. Therefore, this technique shows great potential as a simple and rapid method for studying mechanisms of plant virus infection.

What do men understand about lifetime risk following genetic testing? The effect of context and numeracy.

PubMed

Rolison, Jonathan J; Hanoch, Yaniv; Miron-Shatz, Talya

2012-07-01

Genetic testing for gene mutations associated with specific cancers provides an opportunity for early detection, surveillance, and intervention (Smith, Cokkinides, & Brawley, 2008). Lifetime risk estimates provided by genetic testing refer to the risk of developing a specific disease within one's lifetime, and evidence suggests that this is important for the medical choices people make, as well as their future family and financial plans. The present studies tested whether adult men understand the lifetime risks of prostate cancer informed by genetic testing. In 2 experiments, adult men were asked to interpret the lifetime risk information provided in statements about risks of prostate cancer. Statement format was manipulated such that the most appropriate interpretation of risk statements referred to an absolute risk of cancer in experiment 1 and a relative risk in experiment 2. Experiment 1 revealed that few men correctly interpreted the lifetime risks of cancer when these refer to an absolute risk of cancer, and numeracy levels positively predicted correct responding. The proportion of correct responses was greatly improved in experiment 2 when the most appropriate interpretation of risk statements referred instead to a relative rather than an absolute risk, and numeracy levels were less involved. Understanding of lifetime risk information is often poor because individuals incorrectly believe that these refer to relative rather than absolute risks of cancer.

Patterns of natural mortality in stream-living brown trout (Salmo trutta)

USGS Publications Warehouse

Lobon-Cervia, J.; Budy, P.; Mortensen, E.

2012-01-01

We tested the hypothesis that lifetime mortality patterns and their corresponding rates and causal factors differ among populations of stream-living salmonids. To this end, we examined the lifetime mortality patterns of several successive cohorts of two stream-living brown trout (Salmo trutta) populations in Spain and Denmark. In the southern population, we observed a consistent two-phase pattern, in which mortality was negligible during the first half of the lifetime and severe during the rest of the lifetime. In contrast, the northern population demonstrated a three-phase pattern with an earlier phase varying from negligible to severe, followed by a second stage of weak mortality, and lastly by a third life stage of severe mortality. Despite substantial differences in the mortality patterns between the two populations, the combined effect of recruitment (as a proxy of the density-dependent processes occurring during the lifetime) and mean body mass (as a proxy of growth experienced by individuals in a given cohort) explained c. 89% of the total lifetime mortality rates across cohorts and populations. A comparison with other published data on populations of stream-living brown trout within its native range highlighted lifetime mortality patterns of one, two, three and four phases, but also suggested that common patterns may occur in populations that experience similar individual growth and population density. ?? 2011 Blackwell Publishing Ltd.

Reaction between NiO and Al2O3 in NiO/γ-Al2O3 catalysts probed by positronium atom

NASA Astrophysics Data System (ADS)

Li, C. Y.; Zhang, H. J.; Chen, Z. Q.

2013-02-01

NiO/γ-Al2O3 catalysts with NiO content of 9 wt% and 24 wt% were prepared by solid state reaction method. They are annealed in air at temperatures from 100 °C to 1000 °C. Positron lifetime spectra were measured to study the microstructure variation during annealing process. Four positron lifetime components were resolved with two long lifetime τ3 and τ4, which can be attributed to the ortho-positronium lifetime in microvoids and large pores, respectively. It was found that the longest lifetime τ4 is rather sensitive to the chemical environment of the large pores. The NiO active centers in the catalysts cause decrease of both τ4 and its intensity I4, which is due to the spin-conversion of positronium induced by NiO. However, after heating the catalysts above 600 °C, abnormal increase of the lifetime τ4 is observed. This is due to the formation of NiAl2O4 spinel from the reaction of NiO and γ-Al2O3. The generated NiAl2O4 weakens the spin-conversion effect of positronium, thus leads to the increase of o-Ps lifetime τ4. Formation of NiAl2O4 is further confirmed by both X-ray diffraction and X-ray photoelectron spectroscopy measurements.

Lifetime Traumatic Experiences and Leisure Physical Inactivity among Adolescent Boys.

PubMed

Malinauskas, Romualdas; Malinauskiene, Vilija; Malinauskas, Mindaugas

2018-03-01

The aim of this study was to examine the associations between lifetime traumatic experiences and leisure physical inactivity among adolescent boys and to determine to what extent those associations are mediated by posttraumatic stress symptoms, unhealthy behaviors (smoking, alcohol use), the daily consumption of fresh fruit, and sense of coherence. A self-administered questionnaire combining 3 instruments measured leisure physical activity level (Godin and Shephard), symptoms of posttraumatic stress (IES-revised), lifetime traumatic experiences, sense of coherence (SOC-13, from Antonovsky), and behavioral and dietary patterns in a representative sample of eighth grade boys from a number of Kaunas, Lithuania, secondary schools (N = 885; response rate 88.6%). Fifty-six point eight percent of boys had experienced at least 1 lifetime traumatic event, with a 20.5% prevalence of PTS symptoms, and 5.4% were inactive during leisure time. In the logistic regression models, leisure physical inactivity was associated with lifetime traumatic experiences (adjusted OR = 2.33; 95% CI: 1.09-4.98). Sense of coherence and posttraumatic stress symptoms did not mediate those associations. Less-than-daily consumption of fresh fruit showed an independent effect, while smoking and weekly consumption of alcohol did not. Consistent associations between lifetime traumatic experiences and leisure physical inactivity among adolescent boys indicate that the presence of lifetime traumatic events should be taken into account when employing intervention and prevention programs on unhealthy lifestyles (physical inactivity, smoking, and alcohol).

Cost-Utility Analysis of Bariatric Surgery in Italy: Results of Decision-Analytic Modelling.

PubMed

Lucchese, Marcello; Borisenko, Oleg; Mantovani, Lorenzo Giovanni; Cortesi, Paolo Angelo; Cesana, Giancarlo; Adam, Daniel; Burdukova, Elisabeth; Lukyanov, Vasily; Di Lorenzo, Nicola

2017-01-01

To evaluate the cost-effectiveness of bariatric surgery in Italy from a third-party payer perspective over a medium-term (10 years) and a long-term (lifetime) horizon. A state-transition Markov model was developed, in which patients may experience surgery, post-surgery complications, diabetes mellitus type 2, cardiovascular diseases or die. Transition probabilities, costs, and utilities were obtained from the Italian and international literature. Three types of surgeries were considered: gastric bypass, sleeve gastrectomy, and adjustable gastric banding. A base-case analysis was performed for the population, the characteristics of which were obtained from surgery candidates in Italy. In the base-case analysis, over 10 years, bariatric surgery led to cost increment of EUR 2,661 and generated additional 1.1 quality-adjusted life years (QALYs). Over a lifetime, surgery led to savings of EUR 8,649, additional 0.5 life years and 3.2 QALYs. Bariatric surgery was cost-effective at 10 years with an incremental cost-effectiveness ratio of EUR 2,412/QALY and dominant over conservative management over a lifetime. In a comprehensive decision analytic model, a current mix of surgical methods for bariatric surgery was cost-effective at 10 years and cost-saving over the lifetime of the Italian patient cohort considered in this analysis. © 2017 The Author(s) Published by S. Karger GmbH, Freiburg.

Finite-size effects on bacterial population expansion under controlled flow conditions

NASA Astrophysics Data System (ADS)

Tesser, Francesca; Zeegers, Jos C. H.; Clercx, Herman J. H.; Brunsveld, Luc; Toschi, Federico

2017-03-01

The expansion of biological species in natural environments is usually described as the combined effect of individual spatial dispersal and growth. In the case of aquatic ecosystems flow transport can also be extremely relevant as an extra, advection induced, dispersal factor. We designed and assembled a dedicated microfluidic device to control and quantify the expansion of populations of E. coli bacteria under both co-flowing and counter-flowing conditions, measuring the front speed at varying intensity of the imposed flow. At variance with respect to the case of classic advective-reactive-diffusive chemical fronts, we measure that almost irrespective of the counter-flow velocity, the front speed remains finite at a constant positive value. A simple model incorporating growth, dispersion and drift on finite-size hard beads allows to explain this finding as due to a finite volume effect of the bacteria. This indicates that models based on the Fisher-Kolmogorov-Petrovsky-Piscounov equation (FKPP) that ignore the finite size of organisms may be inaccurate to describe the physics of spatial growth dynamics of bacteria.

Coupled Structural, Thermal, Phase-change and Electromagnetic Analysis for Superconductors, Volume 2

NASA Technical Reports Server (NTRS)

Felippa, C. A.; Farhat, C.; Park, K. C.; Militello, C.; Schuler, J. J.

1996-01-01

Described are the theoretical development and computer implementation of reliable and efficient methods for the analysis of coupled mechanical problems that involve the interaction of mechanical, thermal, phase-change and electromag subproblems. The focus application has been the modeling of superconductivity and associated quantum-state phase change phenomena. In support of this objective the work has addressed the following issues: (1) development of variational principles for finite elements, (2) finite element modeling of the electromagnetic problem, (3) coupling of thermel and mechanical effects, and (4) computer implementation and solution of the superconductivity transition problem. The main accomplishments have been: (1) the development of the theory of parametrized and gauged variational principles, (2) the application of those principled to the construction of electromagnetic, thermal and mechanical finite elements, and (3) the coupling of electromagnetic finite elements with thermal and superconducting effects, and (4) the first detailed finite element simulations of bulk superconductors, in particular the Meissner effect and the nature of the normal conducting boundary layer. The theoretical development is described in two volumes. Volume 1 describes mostly formulation specific problems. Volume 2 describes generalization of those formulations.

Maternal Lifetime Stress and Prenatal Psychological Functioning and Decreased Placental Mitochondrial DNA Copy Number in the PRISM Study.

PubMed

Brunst, Kelly J; Sanchez Guerra, Marco; Gennings, Chris; Hacker, Michele; Jara, Calvin; Bosquet Enlow, Michelle; Wright, Robert O; Baccarelli, Andrea; Wright, Rosalind J

2017-12-01

Psychosocial stress contributes to placental oxidative stress. Mitochondria are vulnerable to oxidative stress, which can lead to changes in mitochondrial DNA copy number (mtDNAcn). We examined associations of maternal lifetime stress, current negative life events, and depressive and posttraumatic-stress-disorder symptom scores with placental mtDNAcn in a racially/ethnically diverse sample (n = 147) from the Programming of Intergenerational Stress Mechanisms (PRISM) study (Massachusetts, March 2011 to August 2012). In linear regression analyses adjusted for maternal age, race/ethnicity, education, prenatal fine particulate matter exposure, prenatal smoking exposure, and the sex of the child, all measures of stress were associated with decreased placental mtDNAcn (all P values < 0.05). Weighted-quantile-sum (WQS) regression showed that higher lifetime stress and depressive symptoms accounted for most of the effect on mtDNAcn (WQS weights: 0.25 and 0.39, respectively). However, among white individuals, increased lifetime stress and posttraumatic stress disorder symptoms explained the majority of the effect (WQS weights: 0.20 and 0.62, respectively) while among nonwhite individuals, lifetime stress and depressive symptoms accounted for most of the effect (WQS weights: 0.27 and 0.55, respectively). These analyses are first to link increased maternal psychosocial stress with reduced placental mtDNAcn and add to literature documenting racial/ethnic differences in the psychological sequelae of chronic stress that may contribute to maternal-fetal health. © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Development of friction and wear full-scale testing for TKR prostheses with reliable low cost apparatus

NASA Astrophysics Data System (ADS)

Suwandi, Agri; Soemardi, Tresna P.; Kiswanto, Gandjar; Kusumaningsih, Widjajalaksmi; I. Gusti Agung I. G., W.

2018-02-01

Prostheses products must undergo simulation and physical testing, before clinical testing. Finite element method is a preliminary simulation for in vivo test. The method visualizes the magnitude of the compressive force and the critical location of the Total Knee Replacement (TKR) prostheses design. In vitro testing is classified as physical testing for prostheses product. The test is conducted to evaluate the potential failure of the product and the characteristics of the prostheses TKR material. Friction and wear testing are part of the in vivo test. Motion of knee joints, which results in the phenomena of extension and deflection in the femoral and tibia insert, is represented by friction and wear testing. Friction and wear tests aim to obtain an approximate lifetime in normal and extreme load patterns as characterized by the shape of the friction surface area. The lifetime estimation requires friction and wear full-scale testing equipments for TKR prostheses products. These are necessary in obtaining initial data on potential product failures and characterizing of the material based on the ASTM F2724-08 standards. Based on the testing result and statistical analysis data, the average wear rate value per year is 2.19 × 10-3 mg/MC, with a 10 % safety limit of volume and 14,400 cycles times, for 15 hours moving nonstop then the prediction of wear life of the component tibia insert is ± 10 years.

Foundations for screening adverse childhood experiences: Exploring patterns of exposure through infancy and toddlerhood.

PubMed

McKelvey, Lorraine M; Selig, James P; Whiteside-Mansell, Leanne

2017-08-01

Adverse childhood experiences (ACEs) have lifetime consequences for health and development. Identification of ACEs early in childhood provides the potential to intervene before health and development are impaired. This study examined the timing and duration of exposure to ACEs experienced by children from low-income families from ages one to three years to identify whether there were patterns of exposure when infants and toddlers were most vulnerable. We were able to confirm the early negative consequences on cognitive, health, and behavior outcomes previously reported in young children using a national, longitudinal data set of parents and children from low-income households (N=2250). Using Finite Mixture Models, five classes of exposure were identified for children, Consistently Low (63.8%), Decreasing (10.3%), High at Age 2 (11.4%), Increasing (10.4%), and Consistently High (4%). The Consistently Low and Consistently High classes had the most and least optimal development across all domains, respectively. When examining child development outcomes among children with variable exposures to adversities, we found that for cognitive, language, and physical development, the most proximal ACEs were more robust for predicting child outcomes. For socioemotional health, exposure at any time from one to three to ACEs had negative consequences. As a whole, findings from this study highlight the need to consider ACEs screening tools that are both time-sensitive and permit a lifetime report. Copyright © 2017 Elsevier Ltd. All rights reserved.

Finite-time master-slave synchronization and parameter identification for uncertain Lurie systems.

PubMed

Wang, Tianbo; Zhao, Shouwei; Zhou, Wuneng; Yu, Weiqin

2014-07-01

This paper investigates the finite-time master-slave synchronization and parameter identification problem for uncertain Lurie systems based on the finite-time stability theory and the adaptive control method. The finite-time master-slave synchronization means that the state of a slave system follows with that of a master system in finite time, which is more reasonable than the asymptotical synchronization in applications. The uncertainties include the unknown parameters and noise disturbances. An adaptive controller and update laws which ensures the synchronization and parameter identification to be realized in finite time are constructed. Finally, two numerical examples are given to show the effectiveness of the proposed method. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Determination of minority-carrier lifetime and surface recombination velocity with high spacial resolution

NASA Technical Reports Server (NTRS)

Watanabe, M.; Actor, G.; Gatos, H. C.

1977-01-01

Quantitative analysis of the electron beam induced current in conjunction with high-resolution scanning makes it possible to evaluate the minority-carrier lifetime three dimensionally in the bulk and the surface recombination velocity two dimensionally, with a high spacial resolution. The analysis is based on the concept of the effective excitation strength of the carriers which takes into consideration all possible recombination sources. Two-dimensional mapping of the surface recombination velocity of phosphorus-diffused silicon diodes is presented as well as a three-dimensional mapping of the changes in the minority-carrier lifetime in ion-implanted silicon.

Adding smoking to the Fardal model of cost-effectiveness for the life-time treatment of periodontal diseases.

PubMed

Fardal, Øystein; Grytten, Jostein; Martin, John; Ellingsen, Stig; Fardal, Patrick; Heasman, Peter; Linden, Gerard J

2018-05-16

Little is known about the financial costs that smoking adds to the life-time treatment of periodontal disease. The total life-time cost of periodontal treatment was modelled using data from private periodontal practice. The costs of initial and supportive therapy, re-treatment and tooth replacements (with bridgework or implants) were identified using average dental charges from the American Dental Association survey. Smoking costs at $6 and $10 for 20 cigarettes were compared to the costs of life-time periodontal treatment for stable and unstable compliant patients. Smoking added 8.8% to the financial cost of the life-time cost of periodontal therapy in stable maintenance patients, 40.1% in patients who needed one extra maintenance visit and 71.4% in patients who needed two extra maintenance visits per year in addition to added re-treatment. The cost of smoking far exceeded the cost of periodontal treatment; For patients who smoked 10 to 40 cigarettes per day at the cost of $6 or $10 a pack, the cost of smoking exceeded the cost of life-time periodontal treatment by between 2.7 and 17.9 times. Smoking 40 cigarettes at $10 a packet for 3.4 years would pay for the entire life-time cost of periodontal treatment. Smoking adds considerable extra financial costs to the life-time treatment of periodontal diseases. The cost of smoking itself exceeds the cost of periodontal therapy. This article is protected by copyright. All rights reserved. © 2018 American Academy of Periodontology.

Electron–Rotor Interaction in Organic–Inorganic Lead Iodide Perovskites Discovered by Isotope Effects

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

Gong, Jue; Yang, Mengjin; Ma, Xiangchao

We report on the carrier-rotor coupling effect in perovskite organic-inorganic hybrid lead iodide (CH3NH3PbI3) compounds discovered by isotope effects. Deuterated organic-inorganic perovskite compounds including CH3ND3PbI3, CD3NH3PbI3, and CD3ND3PbI3 were synthesized. Devices made from regular CH3NH3PbI3 and deuterated CH3ND3PbI3 exhibit comparable performance in band gap, current-voltage, carrier mobility, and power conversion efficiency. However, a time-resolved photoluminescence (TRPL) study reveals that CH3NH3PbI3 exhibits notably longer carrier lifetime than that of CH3ND3PbI3, in both thin-film and single crystal formats. Furthermore, the comparison in carrier lifetime between CD3NH3PbI3 and CH3ND3PbI3 single crystals suggests that vibrational modes in methylammonium (MA(+)) have little impact on carriermore » lifetime. In contrast, the fully deuterated compound CD3ND3PbI3 reconfirmed the trend of decreasing carrier lifetime upon the increasing moment of inertia of cationic MA(+). Polaron model elucidates the electron-rotor interaction.« less

Electron–Rotor Interaction in Organic–Inorganic Lead Iodide Perovskites Discovered by Isotope Effects

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

Gong, Jue; Yang, Mengjin; Ma, Xiangchao

We report on the carrier-rotor coupling effect in perovskite organic-inorganic hybrid lead iodide (CH3NH3PbI3) compounds discovered by isotope effects. Deuterated organic-inorganic perovskite compounds including CH3ND3PbI3, CD3NH3PbI3, and CD3ND3PbI3 were synthesized. Devices made from regular CH3NH3PbI3 and deuterated CH3ND3PbI3 exhibit comparable performance in band gap, current-voltage, carrier mobility, and power conversion efficiency. However, a time-resolved photoluminescence (TRPL) study reveals that CH3NH3PbI3 exhibits notably longer carrier lifetime than that of CH3ND3PbI3, in both thin-film and single-crystal formats. Furthermore, the comparison in carrier lifetime between CD3NH3PbI3 and CH3ND3PbI3 single crystals suggests that vibrational modes in methylammonium (MA+) have little impact on carrier lifetime.more » In contrast, the fully deuterated compound CD3ND3PbI3 reconfirmed the trend of decreasing carrier lifetime upon the increasing moment of inertia of cationic MA+. Polaron model elucidates the electron-rotor interaction.« less

Impulsive-aggressive behaviours and completed suicide across the life cycle: a predisposition for younger age of suicide.

PubMed

McGirr, A; Renaud, J; Bureau, A; Seguin, M; Lesage, A; Turecki, G

2008-03-01

It is unclear whether the association between impulsive-aggressive behaviours and suicide exists across different ages. Via psychological autopsy, we examined a total of 645 subjects aged 11-87 years who died by suicide. Proxy-based interviews were conducted using the SCID-I & SCID-II or K-SADS interviews and a series of behavioural and personality-trait assessments. Secondarily, 246 living controls were similarly assessed. Higher levels of impulsivity, lifetime history of aggression, and novelty seeking were associated with younger age of death by suicide, while increasing levels of harm avoidance were associated with increasing age of suicide. This effect was observed after accounting for age-related psychopathology (current and lifetime depressive disorders, lifetime anxiety disorders, current and lifetime substance abuse disorders, psychotic disorders and cluster B personality disorders). Age effects were not due to the characteristics of informants, and such effects were not observed among living controls. When directly controlling for major psychopathology, the interaction between age, levels of impulsivity, aggression and novelty seeking predicted suicide status while controlling for the independent contributions of age and these traits. Higher levels of impulsive-aggressive traits play a greater role in suicide occurring among younger individuals, with decreasing importance with increasing age.

Electron-Rotor Interaction in Organic-Inorganic Lead Iodide Perovskites Discovered by Isotope Effects.

PubMed

Gong, Jue; Yang, Mengjin; Ma, Xiangchao; Schaller, Richard D; Liu, Gang; Kong, Lingping; Yang, Ye; Beard, Matthew C; Lesslie, Michael; Dai, Ying; Huang, Baibiao; Zhu, Kai; Xu, Tao

2016-08-04

We report on the carrier-rotor coupling effect in perovskite organic-inorganic hybrid lead iodide (CH3NH3PbI3) compounds discovered by isotope effects. Deuterated organic-inorganic perovskite compounds including CH3ND3PbI3, CD3NH3PbI3, and CD3ND3PbI3 were synthesized. Devices made from regular CH3NH3PbI3 and deuterated CH3ND3PbI3 exhibit comparable performance in band gap, current-voltage, carrier mobility, and power conversion efficiency. However, a time-resolved photoluminescence (TRPL) study reveals that CH3NH3PbI3 exhibits notably longer carrier lifetime than that of CH3ND3PbI3, in both thin-film and single-crystal formats. Furthermore, the comparison in carrier lifetime between CD3NH3PbI3 and CH3ND3PbI3 single crystals suggests that vibrational modes in methylammonium (MA(+)) have little impact on carrier lifetime. In contrast, the fully deuterated compound CD3ND3PbI3 reconfirmed the trend of decreasing carrier lifetime upon the increasing moment of inertia of cationic MA(+). Polaron model elucidates the electron-rotor interaction.

A practical model of thin disk regenerative amplifier based on analytical expression of ASE lifetime

NASA Astrophysics Data System (ADS)

Zhou, Huang; Chyla, Michal; Nagisetty, Siva Sankar; Chen, Liyuan; Endo, Akira; Smrz, Martin; Mocek, Tomas

2017-12-01

In this paper, a practical model of a thin disk regenerative amplifier has been developed based on an analytical approach, in which Drew A. Copeland [1] had evaluated the loss rate of the upper state laser level due to ASE and derived the analytical expression of the effective life-time of the upper-state laser level by taking the Lorentzian stimulated emission line-shape and total internal reflection into account. By adopting the analytical expression of effective life-time in the rate equations, we have developed a less numerically intensive model for predicting and analyzing the performance of a thin disk regenerative amplifier. Thanks to the model, optimized combination of various parameters can be obtained to avoid saturation, period-doubling bifurcation or first pulse suppression prior to experiments. The effective life-time due to ASE is also analyzed against various parameters. The simulated results fit well with experimental data. By fitting more experimental results with numerical model, we can improve the parameters of the model, such as reflective factor which is used to determine the weight of boundary reflection within the influence of ASE. This practical model will be used to explore the scaling limits imposed by ASE of the thin disk regenerative amplifier being developed in HiLASE Centre.

DC-Obesity: A New Model for Estimating Differential Lifetime Costs of Overweight and Obesity by Socioeconomic Status.

PubMed

Sonntag, Diana; Jarczok, Marc N; Ali, Shehzad

2017-09-01

The aim of this study was to quantify the magnitude of lifetime costs of overweight and obesity by socioeconomic status (SES). Differential Costs (DC)-Obesity is a new model that uses time-to-event simulation and the Markov modeling approach to compare lifetime excess costs of overweight and obesity among individuals with low, middle, and high SES. SES was measured by a multidimensional aggregated index based on level of education, occupational class, and income by using longitudinal data of the German Socioeconomic Panel (SOEP). Random-effects meta-analysis was applied to combine estimates of (in)direct costs of overweight and obesity. DC-Obesity brings attention to opposite socioeconomic gradients in lifetime costs due to obesity compared to overweight. Compared to individuals with obesity and high SES, individuals with obesity and low SES had lifetime excess costs that were two times higher (€8,526). In contrast, these costs were 20% higher in groups with overweight and high SES than in groups with overweight and low SES (€2,711). The results of this study indicate that SES may play a pivotal role in designing cost-effective and sustainable interventions to prevent and treat overweight and obesity. DC-Obesity may help public policy planners to make informed decisions about obesity programs targeted at vulnerable SES groups. © 2017 The Obesity Society.

Do the cations in clay and the polymer matrix affect quantum dot fluorescent properties?

PubMed

Wei, Wenjun; Liu, Cui; Liu, Jiyan; Liu, Xueqing; Zou, Linling; Cai, Shaojun; Shi, Hong; Cao, Yuan-Cheng

2016-06-01

This paper studied the effects of cations and polymer matrix on the fluorescent properties of quantum dots (QDs). The results indicated that temperature has a greater impact on fluorescence intensity than clay cations (mainly K(+) and Na(+) ). Combined fluorescence lifetime and steady-state spectrometer tests showed that QD lifetimes all decreased when the cation concentration was increased, but the quantum yields were steady at various cation concentrations of 0, 0.05, 0.5 and 1 M. Poly(ethylene oxide) (PEO), poly(vinyl alcohol) (PVA) and diepoxy resin were used to study the effects of polymers on QD lifetime and quantum yield. The results showed that the lifetime for QDs 550 nm in PEO and PVA was 17.33 and 17.12 ns, respectively; for the epoxy resin, the lifetime was 0.74 ns, a sharp decrease from 24.47 ns. The quantum yield for QDs 550 nm changed from 34.22% to 7.45% and 7.81% in PEO and PVA, respectively; for the epoxy resin the quantum yield was 2.25%. QDs 580 nm and 620 nm showed the same results as QDs 550 nm. This study provides useful information on the design, synthesis and application of QDs-polymer luminescent materials. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Finite Element Analysis of Denosumab Treatment Effects on Vertebral Strength in Ovariectomized Cynomolgus Monkeys.

PubMed

Lee, David C; Varela, Aurore; Kostenuik, Paul J; Ominsky, Michael S; Keaveny, Tony M

2016-08-01

Finite element analysis has not yet been validated for measuring changes in whole-bone strength at the hip or spine in people after treatment with an osteoporosis agent. Toward that end, we assessed the ability of a clinically approved implementation of finite element analysis to correctly quantify treatment effects on vertebral strength, comparing against direct mechanical testing, in cynomolgus monkeys randomly assigned to one of three 16-month-long treatments: sham surgery with vehicle (Sham-Vehicle), ovariectomy with vehicle (OVX-Vehicle), or ovariectomy with denosumab (OVX-DMAb). After treatment, T12 vertebrae were retrieved, scanned with micro-CT, and mechanically tested to measure compressive strength. Blinded to the strength data and treatment codes, the micro-CT images were coarsened and homogenized to create continuum-type finite element models, without explicit porosity. With clinical translation in mind, these models were then analyzed for strength using the U.S. Food and Drug Administration (FDA)-cleared VirtuOst software application (O.N. Diagnostics, Berkeley, CA, USA), developed for analysis of human bones. We found that vertebral strength by finite element analysis was highly correlated (R(2)  = 0.97; n = 52) with mechanical testing, independent of treatment (p = 0.12). Further, the size of the treatment effect on strength (ratio of mean OVX-DMAb to mean OVX-Vehicle, as a percentage) was large and did not differ (p = 0.79) between mechanical testing (+57%; 95% CI [26%, 95%]) and finite element analysis (+51% [20%, 88%]). The micro-CT analysis revealed increases in cortical thickness (+45% [19%, 73%]) and trabecular bone volume fraction (+24% [8%, 42%]). These results show that a preestablished clinical finite element analysis implementation-developed for human bone and clinically validated in fracture-outcome studies-correctly quantified the observed treatment effects of denosumab on vertebral strength in cynomolgus monkeys. One implication is that the treatment effects in this study are well explained by the features contained within these finite element models, namely, the bone geometry and mass and the spatial distribution of bone mass. © 2016 American Society for Bone and Mineral Research. © 2016 American Society for Bone and Mineral Research.

Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico

PubMed Central

Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

2015-01-01

Determining ionizing radiation in a geographic area serves to assess its effects on a population’s health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h−1. At the same sites, 48 soil samples were taken to obtain the activity concentrations of 226Ra, 232Th and 40K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h−1. Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg−1, for 226Ra, 232Th and 40K, respectively. From the analysis, the spatial distribution of 232Th, 226Ra and 40K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize. PMID:26437425

Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico.

PubMed

Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

2015-09-30

Determining ionizing radiation in a geographic area serves to assess its effects on a population's health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h(-1). At the same sites, 48 soil samples were taken to obtain the activity concentrations of (226)Ra, (232)Th and (40)K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h(-1). Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg(-1), for (226)Ra, (232)Th and (40)K, respectively. From the analysis, the spatial distribution of (232)Th, (226)Ra and (40)K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize.

A Finite Difference Numerical Model for the Propagation of Finite Amplitude Acoustical Blast Waves Outdoors Over Hard and Porous Surfaces

DTIC Science & Technology

1991-09-01

Difference Numerical Model for the Propagation of Finite Amplitude Acoustical Blast Waves Outdoors Over Hard and Porous Surfaces by Victor W. Sparrow...The nonlinear acoustic propagation effects require a numerical solution in the time domain. To model a porous ground surface, which in the frequency...incident on the hard and porous surfaces were produced. The model predicted that near grazing finite amplitude acoustic blast waves decay with distance

Nilpotent symmetries in supergroup field cosmology

NASA Astrophysics Data System (ADS)

Upadhyay, Sudhaker

2015-06-01

In this paper, we study the gauge invariance of the third quantized supergroup field cosmology which is a model for multiverse. Further, we propose both the infinitesimal (usual) as well as the finite superfield-dependent BRST symmetry transformations which leave the effective theory invariant. The effects of finite superfield-dependent BRST transformations on the path integral (so-called void functional in the case of third quantization) are implemented. Within the finite superfield-dependent BRST formulation, the finite superfield-dependent BRST transformations with specific parameter switch the void functional from one gauge to another. We establish this result for the most general gauge with the help of explicit calculations which holds for all possible sets of gauge choices at both the classical and the quantum levels.

Avalanches, loading and finite size effects in 2D amorphous plasticity: results from a finite element model

NASA Astrophysics Data System (ADS)

Sandfeld, Stefan; Budrikis, Zoe; Zapperi, Stefano; Fernandez Castellanos, David

2015-02-01

Crystalline plasticity is strongly interlinked with dislocation mechanics and nowadays is relatively well understood. Concepts and physical models of plastic deformation in amorphous materials on the other hand—where the concept of linear lattice defects is not applicable—still are lagging behind. We introduce an eigenstrain-based finite element lattice model for simulations of shear band formation and strain avalanches. Our model allows us to study the influence of surfaces and finite size effects on the statistics of avalanches. We find that even with relatively complex loading conditions and open boundary conditions, critical exponents describing avalanche statistics are unchanged, which validates the use of simpler scalar lattice-based models to study these phenomena.

Lattice study of finite volume effect in HVP for muon g-2

NASA Astrophysics Data System (ADS)

Izubuchi, Taku; Kuramashi, Yoshinobu; Lehner, Christoph; Shintani, Eigo

2018-03-01

We study the finite volume effect of the hadronic vacuum polarization contribution to muon g-2, aμhvp, in lattice QCD by comparison with two different volumes, L4 = (5.4)4 and (8.1)4 fm4, at physical pion. We perform the lattice computation of highly precise vector-vector current correlator with optimized AMA technique on Nf = 2 + 1 PACS gauge configurations in Wilson-clover fermion and stout smeared gluon action at one lattice cut-off, a-1 = 2.33 GeV. We compare two integrals of aμhvp, momentum integral and time-slice summation, on the lattice and numerically show that the different size of finite volume effect appears between two methods. We also discuss the effect of backward-state propagation into the result of aμhvp with the different boundary condition. Our model-independent study suggest that the lattice computation at physical pion is important for correct estimate of finite volume and other lattice systematics in aμhvp.

A critical examination of stresses in an elastic single lap joint

NASA Technical Reports Server (NTRS)

Cooper, P. A.; Sawyer, J. W.

1979-01-01

The results of an approximate nonlinear finite-element analysis of a single lap joint are presented and compared with the results of a linear finite-element analysis, and the geometric nonlinear effects caused by the load-path eccentricity on the adhesive stress distributions are determined. The results from finite-element, Goland-Reissner, and photoelastic analyses show that for a single lap joint the effect of the geometric nonlinear behavior of the joint has a sizable effect on the stresses in the adhesive. The Goland-Reissner analysis is sufficiently accurate in the prediction of stresses along the midsurface of the adhesive bond to be used for qualitative evaluation of the influence of geometric or material parametric variations. Detailed stress distributions in both the adherend and adhesive obtained from the finite-element analysis are presented to provide a basis for comparison with other solution techniques.

The effectiveness of element downsizing on a three-dimensional finite element model of bone trabeculae in implant biomechanics.

PubMed

Sato, Y; Wadamoto, M; Tsuga, K; Teixeira, E R

1999-04-01

More validity of finite element analysis in implant biomechanics requires element downsizing. However, excess downsizing needs computer memory and calculation time. To investigate the effectiveness of element downsizing on the construction of a three-dimensional finite element bone trabeculae model, with different element sizes (600, 300, 150 and 75 microm) models were constructed and stress induced by vertical 10 N loading was analysed. The difference in von Mises stress values between the models with 600 and 300 microm element sizes was larger than that between 300 and 150 microm. On the other hand, no clear difference of stress values was detected among the models with 300, 150 and 75 microm element sizes. Downsizing of elements from 600 to 300 microm is suggested to be effective in the construction of a three-dimensional finite element bone trabeculae model for possible saving of computer memory and calculation time in the laboratory.

Particle Orbit Analysis in the Finite Beta Plasma of the Large Helical Device using Real Coordinates

NASA Astrophysics Data System (ADS)

Seki, Ryousuke; Matsumoto, Yutaka; Suzuki, Yasuhiro; Watanabe, Kiyomasa; Itagaki, Masafumi

High-energy particles in a finite beta plasma of the Large Helical Device (LHD) are numerically traced in a real coordinate system. We investigate particle orbits by changing the beta value and/or the magnetic field strength. No significant difference is found in the particle orbit classifications between the vacuum magnetic field and the finite beta plasma cases. The deviation of a banana orbit from the flux surfaces strongly depends on the beta value, although the deviation of the orbit of a passing particle is independent of the beta value. In addition, the deviation of the orbit of the passing particle, rather than that of the banana-orbit particles, depends on the magnetic field strength. We also examine the effect of re-entering particles, which repeatedly pass in and out of the last closed flux surface, in the finite beta plasma of the LHD. It is found that the number of re-entering particles in the finite beta plasma is larger than that in the vacuum magnetic field. As a result, the role of reentering particles in the finite beta plasma of the LHD is more important than that in the vacuum magnetic field, and the effect of the charge-exchange reaction on particle confinement in the finite beta plasma is large.