Temperature dependences of the retention indices of mono- and polyethylene glycol acetals and ethers on stationary phase DB-1 and enthalpies of their sorption from the gas phase

NASA Astrophysics Data System (ADS)

Zhabina, A. A.; Krasnykh, E. L.

2017-12-01

Gas chromatography is used to study the sorption characteristics and retention of a series of mono-, di-, and triethylene glycol ethers on nonpolar phase DB-1 in the temperature range of 70-180°C. Temperature dependences of the retention indices of the compounds are obtained and their linear character in the investigated range of temperatures is demonstrated. The enthalpies of sorption of the investigated compounds are calculated and analyzed, based on the temperature dependences of the retention factors.

Is extinction age dependent?

USGS Publications Warehouse

Doran, N.A.; Arnold, A.J.; Parker, W.C.; Huffer, F.W.

2006-01-01

Age-dependent extinction is an observation with important biological implications. Van Valen's Red Queen hypothesis triggered three decades of research testing its primary implication: that age is independent of extinction. In contrast to this, later studies with species-level data have indicated the possible presence of age dependence. Since the formulation of the Red Queen hypothesis, more powerful tests of survivorship models have been developed. This is the first report of the application of the Cox Proportional Hazards model to paleontological data. Planktonic foraminiferal morphospecies allow the taxonomic and precise stratigraphic resolution necessary for the Cox model. As a whole, planktonic foraminiferal morphospecies clearly show age-dependent extinction. In particular, the effect is attributable to the presence of shorter-ranged species (range < 4 myr) following extinction events. These shorter-ranged species also possess tests with unique morphological architecture. The morphological differences are probably epiphenomena of underlying developmental and heterochronic processes of shorter-ranged species that survived various extinction events. Extinction survivors carry developmental and morphological characteristics into postextinction recovery times, and this sets them apart from species populations established independently of extinction events. Copyright ?? 2006, SEPM (Society for Sedimentary Geology).

Na(+)-dependent transport of taurine is found only on the abluminal membrane of the blood-brain barrier.

PubMed

Rasgado-Flores, Hector; Mokashi, Ashwini; Hawkins, Richard A

2012-01-01

Luminal and abluminal plasma membranes were isolated from bovine brain microvessels and used to identify and characterize Na(+)-dependent and facilitative taurine transport. The calculated transmembrane potential was -59 mV at time 0; external Na(+) (or choline under putative zero-trans conditions) was 126 mM (T=25 °C). The apparent affinity constants of the taurine transporters were determined over a range of taurine concentrations from 0.24 μM to 11.4 μM. Abluminal membranes had both Na(+)-dependent taurine transport as well as facilitative transport while luminal membranes only had facilitative transport. The apparent K(m) for facilitative and Na(+)-dependent taurine transport were 0.06±0.02 μM and 0.7±0.1 μM, respectively. The Na(+)-dependent transport of taurine was voltage dependent over the range of voltages studied (-25 to -101 mV). The transport was over 5 times greater at -101 mV compared to when V(m) was -25 mV. The sensitivity to external osmolality of Na(+)-dependent transport was studied over a range of osmolalities (229 to 398 mOsm/kg H(2)O) using mannitol as the osmotic agent to adjust the osmolality. For these experiments the concentration of Na(+) was maintained constant at 50mM, and the calculated transmembrane potential was -59 mV. The Na(+)-dependent transport system was sensitive to osmolality with the greatest rate observed at 229 mOsm/kg H(2)O. Copyright © 2011 Elsevier Inc. All rights reserved.

Polymorphisms in genes encoding dopamine signalling pathway and risk of alcohol dependence: a systematic review.

PubMed

Bhaskar, Lakkakula V K S; Kumar, Shanmugasundaram Arun

2014-04-01

Alcohol dependence (AD) is one of the major elements that significantly influence drinking pattern that provoke the alcohol-induced organ damage. The structural and neurophysiologic abnormalities in the frontal lobes of chronic alcoholics were revealed by magnetic resonance imaging scans. It is well known that candidate genes involved in dopaminergic pathway are of immense interest to the researchers engaged in a wide range of addictive disorders. Dopaminergic pathway gene polymorphisms are being extensively studied with respect to addictive and behavioral disorders. From the broad literature available, the current review summarizes the specific polymorphisms of dopaminergic genes that play a role in alcohol dependence. No evidence indicating any strong association between AD and polymorphisms of dopamine pathway genes has emerged from the literature. Further studies are warranted, considering a range of alcohol-related traits to determine the genes that influence alcohol dependence.

Effect of interaction range on phonon relaxation in Fermi-Pasta-Ulam beta chain.

PubMed

Santhosh, G; Kumar, Deepak

2007-08-01

We study the effect of increasing the range of interactions on phonon relaxation in a chain of atoms with quartic anharmonicity. The study is motivated by recent numerical studies, showing that the value of the exponent alpha characterizing the divergence of conductivity with system size apparently depends on the presence of second neighbor couplings. We perform a quantum calculation of the wave-vector (q) dependent relaxation rate gamma(q) in the second order perturbation theory. The nonanalytic dependence of gamma(q) arises due to small-q singularity of the collision integral. We find that gamma(q) proportional to Aq(5/3) + Bq2. This gives rise to an asymptotic value alpha = 0.4, but the q2 terms lead to a higher apparent value of alpha at small sizes of the chain.

Development of dependence following treatment with opioid analgesics for pain relief: a systematic review.

PubMed

Minozzi, Silvia; Amato, Laura; Davoli, Marina

2013-04-01

To assess the incidence or prevalence of opioid dependence syndrome in adults (with and without previous history of substance abuse) following treatment with opioid analgesics for pain relief. Medline, Embase, CINHAL and the Cochrane Library were searched up to January 2011. Systematic reviews and primary studies were included if they reported data about incidence or prevalence of opioid dependence syndrome (as defined by DSM-IV or ICD-10) in patients receiving strong opioids (or opioid-type analgesics) for treatment of acute or chronic pain due to any physical condition. The data were abstracted, and the methodological quality was assessed using validated checklists. Data were extracted from 17 studies involving a total of 88 235 participants. The studies included three systematic reviews, one randomized controlled trial, eight cross-sectional studies and four uncontrolled case series. Most studies included adult patients with chronic non-malignant pain; two also included patients with cancer pain; only one included patients with a previous history of dependence. Incidence ranged from 0 to 24% (median 0.5%); prevalence ranged from 0 to 31% (median 4.5%). The available evidence suggests that opioid analgesics for chronic pain conditions are not associated with a major risk for developing dependence. © 2012 The Authors, Addiction © 2012 Society for the Study of Addiction.

Efficient design of cluster randomized trials with treatment-dependent costs and treatment-dependent unknown variances.

PubMed

van Breukelen, Gerard J P; Candel, Math J J M

2018-06-10

Cluster randomized trials evaluate the effect of a treatment on persons nested within clusters, where treatment is randomly assigned to clusters. Current equations for the optimal sample size at the cluster and person level assume that the outcome variances and/or the study costs are known and homogeneous between treatment arms. This paper presents efficient yet robust designs for cluster randomized trials with treatment-dependent costs and treatment-dependent unknown variances, and compares these with 2 practical designs. First, the maximin design (MMD) is derived, which maximizes the minimum efficiency (minimizes the maximum sampling variance) of the treatment effect estimator over a range of treatment-to-control variance ratios. The MMD is then compared with the optimal design for homogeneous variances and costs (balanced design), and with that for homogeneous variances and treatment-dependent costs (cost-considered design). The results show that the balanced design is the MMD if the treatment-to control cost ratio is the same at both design levels (cluster, person) and within the range for the treatment-to-control variance ratio. It still is highly efficient and better than the cost-considered design if the cost ratio is within the range for the squared variance ratio. Outside that range, the cost-considered design is better and highly efficient, but it is not the MMD. An example shows sample size calculation for the MMD, and the computer code (SPSS and R) is provided as supplementary material. The MMD is recommended for trial planning if the study costs are treatment-dependent and homogeneity of variances cannot be assumed. © 2018 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd.

Size-dependent phase diagrams of metallic alloys: A Monte Carlo simulation study on order–disorder transitions in Pt–Rh nanoparticles

PubMed Central

Stahl, Christian; Albe, Karsten

2012-01-01

Summary Nanoparticles of Pt–Rh were studied by means of lattice-based Monte Carlo simulations with respect to the stability of ordered D022- and 40-phases as a function of particle size and composition. By thermodynamic integration in the semi-grand canonical ensemble, phase diagrams for particles with a diameter of 7.8 nm, 4.3 nm and 3.1 nm were obtained. Size-dependent trends such as the lowering of the critical ordering temperature, the broadening of the compositional stability range of the ordered phases, and the narrowing of the two-phase regions were observed and discussed in the context of complete size-dependent nanoparticle phase diagrams. In addition, an ordered surface phase emerges at low temperatures and low platinum concentration. A decrease of platinum surface segregation with increasing global platinum concentration was observed, when a second, ordered phase is formed inside the core of the particle. The order–disorder transitions were analyzed in terms of the Warren–Cowley short-range order parameters. Concentration-averaged short-range order parameters were used to remove the surface segregation bias of the conventional short-range order parameters. Using this procedure, it was shown that the short-range order in the particles at high temperatures is bulk-like. PMID:22428091

Charge transfer optical absorption and fluorescence emission of 4-(9-acridyl)julolidine from long-range-corrected time dependent density functional theory in polarizable continuum approach.

PubMed

Kityk, A V

2014-07-15

A long-range-corrected time-dependent density functional theory (LC-TDDFT) in combination with polarizable continuum model (PCM) have been applied to study charge transfer (CT) optical absorption and fluorescence emission energies basing on parameterized LC-BLYP xc-potential. The molecule of 4-(9-acridyl)julolidine selected for this study represents typical CT donor-acceptor dye with strongly solvent dependent optical absorption and fluorescence emission spectra. The result of calculations are compared with experimental spectra reported in the literature to derive an optimal value of the model screening parameter ω. The first absorption band appears to be quite well predictable within DFT/TDDFT/PCM with the screening parameter ω to be solvent independent (ω ≈ 0.245 Bohr(-1)) whereas the fluorescence emission exhibits a strong dependence on the range separation with ω-value varying on a rising solvent polarity from about 0.225 to 0.151 Bohr(-1). Dipolar properties of the initial state participating in the electronic transition have crucial impact on the effective screening. Copyright © 2014 Elsevier B.V. All rights reserved.

Two-range magnetoelectric sensor

NASA Astrophysics Data System (ADS)

Bichurin, M.; Petrov, V.; Leontyev, V.; Saplev, A.

2017-01-01

In this study, we present a two-range magnetoelectric ME sensor design comprising of permendur (alloy of Fe-Co-V), nickel, and lead zirconate titanate (PZT) laminate composite. A systematic study was conducted to clarify the contribution of magnetostrictive layers variables to the ME response over the applied range of magnetic bias field. The two-range behavior was characterized by opposite sign of the ME response when magnetic dc bias is in different sub-ranges. The ME coefficient as a function of magnetic bias field was found to be dependent on the laminate composite structure.

[The dependence of the range of fusion on some selected functions of the visual system. Part II: Accommodation and dominance].

PubMed

Adamek, Bogdan; Karczewicz, Danuta

2006-01-01

This present study is the continuation of Part I of the research into the range of fusion in which the difference between both eyeballs as far as convergent fusion is concerned was described. The phenomenon was called "visual unevenness of the range of convergent fusion". This part of the study is devoted to the analysis of the relationship between the unevenness of the fusion, ocular dominance and accommodation. A lower range of convergent fusion was observed in the dominant eye with the higher accommodation, In contrast, a higher range of fusion was observed in the not dominant eye with lower accommodation. The authors think that the phenomenon of ocular unevenness of the range of convergent fusion does not depend on the peripheral part of visual organ. In fact, it does seem to point out to a cortical process. The authors suggest that quantitative tests on amplitude of fusion should be carried out first on the first eye and then on the other. The results obtained from both eyes should be compared with each other.

Prevalence and psychosocial determinants of nicotine dependence in nine countries of the former Soviet Union.

PubMed

Roberts, Bayard; Gilmore, Anna; Stickley, Andrew; Kizilova, Kseniya; Prohoda, Vladimir; Rotman, David; Haerpfer, Christian; McKee, Martin

2013-01-01

Despite the high prevalence of smoking in the former Soviet Union (fSU), particularly among men, there is very little information on nicotine dependence in the region. The study aim was to describe the prevalence of nicotine dependence in 9 countries of the fSU and to examine the psychosocial factors associated with nicotine dependence. Cross-sectional, nationally representative surveys using multistage random sampling were conducted in 2010 with men and women aged 18 years and over in Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russia, and Ukraine. The main outcome of interest was nicotine dependence using the Fagerström Test for Nicotine Dependence. Multivariate regression analysis was then used to explore the influence of a range of psychosocial factors on higher nicotine dependence. Mean nicotine dependence among men in the region as a whole was 3.96, with high dependence ranging from 17% in Belarus to 40% in Georgia. Among women, mean dependence was 2.96, with a prevalence of high dependence of 11% for the region. Gender (men), younger age of first smoking, lower education level, not being a member of an organization, bad household economic situation, high alcohol dependence, and high psychological distress showed significant associations with higher nicotine dependence. High nicotine dependence among men was recorded in a number of study countries. Findings highlight the need for tobacco programmes to target early age smokers and less educated and poorer groups and suggest common ground for programmes seeking to reduce nicotine dependence, harmful alcohol use, and psychological distress.

SU-E-T-586: Field Size Dependence of Output Factor for Uniform Scanning Proton Beams: A Comparison of TPS Calculation, Measurement and Monte Carlo Simulation

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

Zheng, Y; Singh, H; Islam, M

2014-06-01

Purpose: Output dependence on field size for uniform scanning beams, and the accuracy of treatment planning system (TPS) calculation are not well studied. The purpose of this work is to investigate the dependence of output on field size for uniform scanning beams and compare it among TPS calculation, measurements and Monte Carlo simulations. Methods: Field size dependence was studied using various field sizes between 2.5 cm diameter to 10 cm diameter. The field size factor was studied for a number of proton range and modulation combinations based on output at the center of spread out Bragg peak normalized to amore » 10 cm diameter field. Three methods were used and compared in this study: 1) TPS calculation, 2) ionization chamber measurement, and 3) Monte Carlos simulation. The XiO TPS (Electa, St. Louis) was used to calculate the output factor using a pencil beam algorithm; a pinpoint ionization chamber was used for measurements; and the Fluka code was used for Monte Carlo simulations. Results: The field size factor varied with proton beam parameters, such as range, modulation, and calibration depth, and could decrease over 10% from a 10 cm to 3 cm diameter field for a large range proton beam. The XiO TPS predicted the field size factor relatively well at large field size, but could differ from measurements by 5% or more for small field and large range beams. Monte Carlo simulations predicted the field size factor within 1.5% of measurements. Conclusion: Output factor can vary largely with field size, and needs to be accounted for accurate proton beam delivery. This is especially important for small field beams such as in stereotactic proton therapy, where the field size dependence is large and TPS calculation is inaccurate. Measurements or Monte Carlo simulations are recommended for output determination for such cases.« less

Anhedonia in substance use disorders: a systematic review of its nature, course and clinical correlates.

PubMed

Garfield, Joshua B B; Lubman, Dan I; Yücel, Murat

2014-01-01

There is growing evidence that anhedonia is a commonly experienced symptom among substance-using populations. This systematic review synthesises findings across a range of substances to address questions regarding the time course of anhedonia, how anhedonia relates to other symptoms of substance dependence and whether it is similarly prevalent across all addictive drugs. A literature search was conducted on PubMed, PsycINFO and MEDLINE, yielding 32 studies that used self-report measures of anhedonia among participants with a history of a substance abuse, dependence or long-term daily use of addictive substances. Findings from these studies indicate that anhedonia (1) is elevated in samples dependent on a range of substances; (2) typically appears as a consequence of substance abuse or dependence, and diminishes with abstinence; and (3) predicts increased drug cravings and the likelihood of relapse in those attempting abstinence. The common experience of anhedonia in substance-dependent populations, and its relationship to relapse, emphasises the importance of developing therapeutic interventions that specifically target anhedonia in the treatment of all substance use disorders.

Viscoelastic properties of human and bovine articular cartilage: a comparison of frequency-dependent trends.

PubMed

Temple, Duncan K; Cederlund, Anna A; Lawless, Bernard M; Aspden, Richard M; Espino, Daniel M

2016-10-06

The purpose of this study was to compare the frequency-dependent viscoelastic properties of human and bovine cartilage. Full-depth cartilage specimens were extracted from bovine and human femoral heads. Using dynamic mechanical analysis, the viscoelastic properties of eight bovine and six human specimens were measured over the frequency range 1 Hz to 88 Hz. Significant differences between bovine and human cartilage viscoelastic properties were assessed using a Mann-Whitney test (p < 0.05). Throughout the range of frequencies tested and for both species, the storage modulus was greater than the loss modulus and both were frequency-dependent. The storage and loss moduli of all human and bovine cartilage specimens presented a logarithmic relationship with respect to frequency. The mean human storage modulus ranged from 31.9 MPa to 43.3 MPa, while the mean bovine storage modulus ranged from 54.0 MPa to 80.5 MPa; bovine storage moduli were 1.7 to 1.9 times greater than the human modulus. Similarly, the loss modulus of bovine cartilage was 2.0 to 2.1 times greater than human. The mean human loss modulus ranged from 5.3 MPa to 8.5 MPa while bovine moduli ranged from 10.6 MPa to 18.1 MPa. Frequency-dependent viscoelastic trends of bovine articular cartilage were consistent with those of human articular cartilage; this includes a similar frequency dependency and high-frequency plateau. Bovine cartilage was, however, 'stiffer' than human by a factor of approximately 2. With these provisos, bovine articular cartilage may be a suitable dynamic model for human articular cartilage.

Dynamical properties in supercooling liquid of trehalose aqueous solution studied by Brillouin scattering

NASA Astrophysics Data System (ADS)

Shibata, Tomohiko; Tominaga, Ayane; Takayama, Haruki; Kojima, Seiji

2013-02-01

Brillouin scattering spectroscopy has been applied to study the dynamical properties of glass transition of trehalose aqueous solutions in a high-frequency gigahertz range and in the temperature range (-190°C ≤ T ≤ 100°C). The temperature variations of sound velocity and attenuation were accurately determined using the refractive index measured by a prism-coupling method. The temperature dependence of relaxation time of the structural relaxation process was determined by the Debye model. Its temperature dependence shows Arrhenius behavior in a liquid state. The parameters of Arrhenius law were also determined as a function of trehalose concentration.

Generalization of symmetric α-stable Lévy distributions for q >1

NASA Astrophysics Data System (ADS)

Umarov, Sabir; Tsallis, Constantino; Gell-Mann, Murray; Steinberg, Stanly

2010-03-01

The α-stable distributions introduced by Lévy play an important role in probabilistic theoretical studies and their various applications, e.g., in statistical physics, life sciences, and economics. In the present paper we study sequences of long-range dependent random variables whose distributions have asymptotic power-law decay, and which are called (q,α)-stable distributions. These sequences are generalizations of independent and identically distributed α-stable distributions and have not been previously studied. Long-range dependent (q,α)-stable distributions might arise in the description of anomalous processes in nonextensive statistical mechanics, cell biology, finance. The parameter q controls dependence. If q =1 then they are classical independent and identically distributed with α-stable Lévy distributions. In the present paper we establish basic properties of (q,α)-stable distributions and generalize the result of Umarov et al. [Milan J. Math. 76, 307 (2008)], where the particular case α =2,qɛ[1,3) was considered, to the whole range of stability and nonextensivity parameters α ɛ(0,2] and q ɛ[1,3), respectively. We also discuss possible further extensions of the results that we obtain and formulate some conjectures.

Investigation of conduction and relaxation phenomena in BaZrxTi1-xO3 (x=0.05) by impedance spectroscopy

NASA Astrophysics Data System (ADS)

Mahajan, Sandeep; Haridas, Divya; Ali, S. T.; Munirathnam, N. R.; Sreenivas, K.; Thakur, O. P.; Prakash, Chandra

2014-10-01

In present study we have prepared ferroelectric BaZrxTi1-xO3 (x=0.05) ceramic by conventional solid state reaction route and studied its electrical properties as a function of temperature and frequency. X-ray diffraction (XRD) analysis shows single-phase formation of the compound with orthorhombic crystal structure at room temperature. Impedance and electric modulus spectroscopy analysis in the frequency range of 40 Hz-1 MHz at high temperature (200-600 °C) suggests two relaxation processes with different time constant are involved which are attributed to bulk and grain boundary effects. Frequency dependent dielectric plot at different temperature shows normal variation with frequency while dielectric loss (tanδ) peak was found to obey an Arrhenius law with activation energy of 1.02 eV. The frequency-dependent AC conductivity data were also analyzed in a wide temperature range. In present work we have studied the role of grain and grain boundaries on the electrical behaviour of Zr-doped BaTiO3 and their dependence on temperature and frequency by complex impedance and modulus spectroscopy (CIS) technique in a wide frequency (40 Hz-1 MHz) and high temperature range.

Motivation and exercise dependence: a study based on self-determination theory.

PubMed

González-Cutre, David; Sicilia, Alvaro

2012-06-01

The objective of this study was to use self-determination theory to analyze the relationships of several motivational variables with exercise dependence. The study involved 531 exercisers, ranging in age from 16 to 60 years old, who responded to differentquestionnaires assessing perception of motivational climate, satisfaction of basic psychological needs, motivation types, and exercise dependence. The results of multiple mediation analysis revealed that ego-involving climate and perceived competence positively predicted exercise dependence in a directed and mediated manner through introjected and external regulation. Gender and age did not moderate the analyzed relationships. These results allow us to better understand the motivational process explaining exercise dependence, demonstrating the negative influence of the ego-involving climate in the context of exercise.

Evidence for density dependence in foraging and migratory behavior of a subtropical nearshore seabird

USGS Publications Warehouse

Lamb, Juliet S.; Satgé, Yvan G.; Jodice, Patrick G. R.

2017-01-01

Density-dependent competition for food resources influences both foraging ecology and reproduction in a variety of animals. The relationship between colony size, local prey depletion, and reproductive output in colonial central-place foragers has been extensively studied in seabirds; however, most studies have focused on effects of intraspecific competition during the breeding season, while little is known about whether density-dependent resource depletion influences individual migratory behavior outside the breeding season. Using breeding colony size as a surrogate for intraspecific resource competition, we tested for effects of colony size on breeding home range, nestling health, and migratory patterns of a nearshore colonial seabird, the brown pelican (Pelecanus occidentalis), originating from seven breeding colonies of varying sizes in the subtropical northern Gulf of Mexico. We found evidence for density-dependent effects on foraging behavior during the breeding season, as individual foraging areas increased linearly with the number of breeding pairs per colony. Contrary to our predictions, however, nestlings from more numerous colonies with larger foraging ranges did not experience either decreased condition or increased stress. During nonbreeding, individuals from larger colonies were more likely to migrate, and traveled longer distances, than individuals from smaller colonies, indicating that the influence of density-dependent effects on distribution persists into the nonbreeding period. We also found significant effects of individual physical condition, particularly body size, on migratory behavior, which in combination with colony size suggesting that dominant individuals remain closer to breeding sites during winter. We conclude that density-dependent competition may be an important driver of both the extent of foraging ranges and the degree of migration exhibited by brown pelicans. However, the effects of density-dependent competition on breeding success and population regulation remain uncertain in this system.

Evolution of density-dependent movement during experimental range expansions.

PubMed

Fronhofer, E A; Gut, S; Altermatt, F

2017-12-01

Range expansions and biological invasions are prime examples of transient processes that are likely impacted by rapid evolutionary changes. As a spatial process, range expansions are driven by dispersal and movement behaviour. Although it is widely accepted that dispersal and movement may be context-dependent, for instance density-dependent, and best represented by reaction norms, the evolution of density-dependent movement during range expansions has received little experimental attention. We therefore tested current theory predicting the evolution of increased movement at low densities at range margins using highly replicated and controlled range expansion experiments across multiple genotypes of the protist model system Tetrahymena thermophila. Although rare, we found evolutionary changes during range expansions even in the absence of initial standing genetic variation. Range expansions led to the evolution of negatively density-dependent movement at range margins. In addition, we report the evolution of increased intrastrain competitive ability and concurrently decreased population growth rates in range cores. Our findings highlight the importance of understanding movement and dispersal as evolving reaction norms and plastic life-history traits of central relevance for range expansions, biological invasions and the dynamics of spatially structured systems in general. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Time-of-day effects on voice range profile performance in young, vocally untrained adult females.

PubMed

van Mersbergen, M R; Verdolini, K; Titze, I R

1999-12-01

Time-of-day effects on voice range profile performance were investigated in 20 vocally healthy untrained women between the ages of 18 and 35 years. Each subject produced two complete voice range profiles: one in the morning and one in the evening, about 36 hours apart. The order of morning and evening trials was counterbalanced across subjects. Dependent variables were (1) average minimum and average maximum intensity, (2) Voice range profile area and (3) center of gravity (median semitone pitch and median intensity). In this study, the results failed to reveal any clear evidence of time-of-day effects on voice range profile performance, for any of the dependent variables. However, a reliable interaction of time-of-day and trial order was obtained for average minimum intensity. Investigation of other subject populations, in particular trained vocalists or those with laryngeal lesions, is required for any generalization of the results.

Valorization of cruor slaughterhouse by-product by enzymatic hydrolysis for the production of antibacterial peptides: focus on α 1-32 family peptides mechanism and kinetics modeling.

PubMed

Hedhili, K; Dimitrov, K; Vauchel, P; Sila, A; Chataigné, G; Dhulster, P; Nedjar, N

2015-10-01

Bovine hemoglobin is the major component of the cruor (slaughterhouse by-product) and can be considered as an important source of active peptides that could be obtained by pepsic hydrolysis. The kinetics of appearance and disappearance of several antibacterial peptides from α 1-32 family during hydrolysis of synthesized α 1-32 peptide, of purified bovine hemoglobin and of cruor was studied, and reaction scheme for the hydrolysis of α 1-32 family peptides from these three sources was determined. On this basis, a mathematical model was proposed to predict the concentration of each peptide of interest of this family depending on hydrolysis time, and also on temperature (in the range 15-37 °C), pH (in the range 3.5-5.5) and enzyme to substrate ratio (in the range 1/50-1/200 for the synthesized peptide and 1/5-1/20 for purified bovine hemoglobin and cruor). Apparent rate constants of reactions were determined by applying the model on a set of experimental data and it was shown that they depended on the temperature according to Arrhenius's law, that their dependence on the pH was linear, and that enzyme to substrate ratio influence was limited (in the studied range).

D.C. electrical conductivity and conduction mechanism of some azo sulfonyl quinoline ligands and uranyl complexes.

PubMed

El-Ghamaz, N A; Diab, M A; El-Sonbati, A Z; Salem, O L

2011-12-01

Supramolecular coordination of dioxouranium(VI) heterochelates 5-sulphono-7-(4'-X phenylazo)-8-hydroxyquinoline HL(n) (n=1, X=CH(3); n=2, X=H; n=3, X=Cl; n=4, X=NO(2)) have been prepared and characterized with various physico-chemical techniques. The infrared spectral studies showed a monobasic bidentate behavior with the oxygen and azonitrogen donor system. The temperature dependence of the D.C. electrical conductivity of HL(n) ligands and their uranyl complexes has been studied in the temperature range 305-415 K. The thermal activation energies E(a) for HL(n) compounds were found to be in the range 0.44-0.9 eV depending on the nature of the substituent X. The complexation process decreased E(a) values to the range 0.043-045 eV. The electrical conduction mechanism has been investigated for all samples under investigation. It was found to obey the variable range hopping mechanism (VRH). Copyright © 2011 Elsevier B.V. All rights reserved.

Population genetic analysis of Bromus tectorum (Poaceae) indicates recent range expansion may be facilitated by specialist genotypes

Treesearch

Keith R. Merrill; Susan E. Meyer; Craig E. Coleman

2012-01-01

The mechanisms for range expansion in invasive species depend on how genetic variation is structured in the introduced range. This study examined neutral genetic variation in the invasive annual grass Bromus tectorum in the Intermountain Western United States. Patterns of microsatellite (SSR) genotype distribution in this highly inbreeding species were used to make...

Range expansion promotes cooperation in an experimental microbial metapopulation

PubMed Central

Datta, Manoshi Sen; Korolev, Kirill S.; Cvijovic, Ivana; Dudley, Carmel; Gore, Jeff

2013-01-01

Natural populations throughout the tree of life undergo range expansions in response to changes in the environment. Recent theoretical work suggests that range expansions can have a strong effect on evolution, even leading to the fixation of deleterious alleles that would normally be outcompeted in the absence of migration. However, little is known about how range expansions might influence alleles under frequency- or density-dependent selection. Moreover, there is very little experimental evidence to complement existing theory, since expanding populations are difficult to study in the natural environment. In this study, we have used a yeast experimental system to explore the effect of range expansions on the maintenance of cooperative behaviors, which commonly display frequency- and density-dependent selection and are widespread in nature. We found that range expansions favor the maintenance of cooperation in two ways: (i) through the enrichment of cooperators at the front of the expanding population and (ii) by allowing cooperators to “outrun” an invading wave of defectors. In this system, cooperation is enhanced through the coupling of population ecology and evolutionary dynamics in expanding populations, thus providing experimental evidence for a unique mechanism through which cooperative behaviors could be maintained in nature. PMID:23569263

Dosimetric characterization of a single crystal diamond detector in X-ray beams for preclinical research.

PubMed

Kampfer, Severin; Cho, Nathan; Combs, Stephanie E; Wilkens, Jan J

2018-05-29

The aim of this study was to investigate a single crystal diamond detector, the microDiamond detector from PTW (PTW-Freiburg, Freiburg, Germany), concerning the particular requirements in the set-up and energy range used in small animal radiotherapy (RT) research (around 220kV). We tested it to find out the minimal required pre-irradiation dose, the dose linearity, dose rate dependency and the angular response as well as usability in the small animal radiation research platform, SARRP (Xstrahl Ltd., Camberley, UK). For a stable signal in the range of energies used in the study, we found a required pre-irradiation dose of 10Gy. The dose linearity and dose rate dependence measurements showed a very good performance of the microDiamond detector. Regarding the effect of angular dependency, the variation of the response signal is less than 0.5% within the first 15° of the polar angle. In the azimuthal angle, however, there are differences in detector response up to 20%, depending on the range of energies used in the study. In addition, we compared the detector to a radiosensitive film for a profile measurement of a 5×5mm 2 irradiation field. Both methods showed a good accordance with the field size, however, the film has a steeper dose gradient in the penumbra region but also a higher noise than the microDiamond detector. We demonstrated that the microDiamond detector is a useful measurement tool for small animal RT research due to its small size. Nevertheless, it seems to be very important to verify the response of the detector in the given set-up and energy range. Copyright © 2018. Published by Elsevier GmbH.

Actin cables and the exocyst form two independent morphogenesis pathways in the fission yeast

PubMed Central

Bendezú, Felipe O.; Martin, Sophie G.

2011-01-01

Cell morphogenesis depends on polarized exocytosis. One widely held model posits that long-range transport and exocyst-dependent tethering of exocytic vesicles at the plasma membrane sequentially drive this process. Here, we describe that disruption of either actin-based long-range transport and microtubules or the exocyst did not abolish polarized growth in rod-shaped fission yeast cells. However, disruption of both actin cables and exocyst led to isotropic growth. Exocytic vesicles localized to cell tips in single mutants but were dispersed in double mutants. In contrast, a marker for active Cdc42, a major polarity landmark, localized to discreet cortical sites even in double mutants. Localization and photobleaching studies show that the exocyst subunits Sec6 and Sec8 localize to cell tips largely independently of the actin cytoskeleton, but in a cdc42 and phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2)–dependent manner. Thus in fission yeast long-range cytoskeletal transport and PIP2-dependent exocyst represent parallel morphogenetic modules downstream of Cdc42, raising the possibility of similar mechanisms in other cell types. PMID:21148300

State-dependent behavior alters endocrine–energy relationship: Implications for conservation and management

USGS Publications Warehouse

Jesmer, Brett R.; Goheen, Jacob R.; Monteith, Kevin L.; Kauffman, Matthew J.

2017-01-01

Glucocorticoids (GC) and triiodothyronine (T3) are two endocrine markers commonly used to quantify resource limitation, yet the relationships between these markers and the energetic state of animals has been studied primarily in small-bodied species in captivity. Free-ranging animals, however, adjust energy intake in accordance with their energy reserves, a behavior known as state-dependent foraging. Further, links between life-history strategies and metabolic allometries cause energy intake and energy reserves to be more strongly coupled in small animals relative to large animals. Because GC and T3 may reflect energy intake or energy reserves, state-dependent foraging and body size may cause endocrine–energy relationships to vary among taxa and environments. To extend the utility of endocrine markers to large-bodied, free-ranging animals, we evaluated how state-dependent foraging, energy reserves, and energy intake influenced fecal GC and fecal T3 concentrations in free-ranging moose (Alces alces). Compared with individuals possessing abundant energy reserves, individuals with few energy reserves had higher energy intake and high fecal T3 concentrations, thereby supporting state-dependent foraging. Although fecal GC did not vary strongly with energy reserves, individuals with higher fecal GC tended to have fewer energy reserves and substantially greater energy intake than those with low fecal GC. Consequently, individuals with greater energy intake had both high fecal T3 and high fecal GC concentrations, a pattern inconsistent with previous documentation from captive animal studies. We posit that a positive relationship between GC and T3 may be expected in animals exhibiting state-dependent foraging if GC is associated with increased foraging and energy intake. Thus, we recommend that additional investigations of GC– and T3–energy relationships be conducted in free-ranging animals across a diversity of body size and life-history strategies before these endocrine markers are applied broadly to wildlife conservation and management.

Efros-Shklovskii variable range hopping and nonlinear transport in 1 T /1 T'-MoS2

NASA Astrophysics Data System (ADS)

Papadopoulos, N.; Steele, G. A.; van der Zant, H. S. J.

2017-12-01

We have studied temperature- and electric-field-dependent carrier transport in single flakes of MoS2 treated with n -butyllithium. The temperature dependence of the four-terminal resistance follows the Efros-Shklovskii variable range hopping conduction mechanism. From measurements in the Ohmic and non-Ohmic regime, we estimate the localization length and the average hopping length of the carriers, as well as the effective dielectric constant. Furthermore, a comparison between two- and four-probe measurements yields a contact resistance that increases significantly with decreasing temperature.

Application of commercial MOSFET detectors for in vivo dosimetry in the therapeutic x-ray range from 80 kV to 250 kV

NASA Astrophysics Data System (ADS)

Ehringfeld, Christian; Schmid, Susanne; Poljanc, Karin; Kirisits, Christian; Aiginger, Hannes; Georg, Dietmar

2005-01-01

The purpose of this study was to investigate the dosimetric characteristics (energy dependence, linearity, fading, reproducibility, etc) of MOSFET detectors for in vivo dosimetry in the kV x-ray range. The experience of MOSFET in vivo dosimetry in a pre-clinical study using the Alderson phantom and in clinical practice is also reported. All measurements were performed with a Gulmay D3300 kV unit and TN-502RDI MOSFET detectors. For the determination of correction factors different solid phantoms and a calibrated Farmer-type chamber were used. The MOSFET signal was linear with applied dose in the range from 0.2 to 2 Gy for all energies. Due to fading it is recommended to read the MOSFET signal during the first 15 min after irradiation. For long time intervals between irradiation and readout the fading can vary largely with the detector. The temperature dependence of the detector signal was small (0.3% °C-1) in the temperature range between 22 and 40 °C. The variation of the measuring signal with beam incidence amounts to ±5% and should be considered in clinical applications. Finally, for entrance dose measurements energy-dependent calibration factors, correction factors for field size and irradiated cable length were applied. The overall accuracy, for all measurements, was dominated by reproducibility as a function of applied dose. During the pre-clinical in vivo study, the agreement between MOSFET and TLD measurements was well within 3%. The results of MOSFET measurements, to determine the dosimetric characteristics as well as clinical applications, showed that MOSFET detectors are suitable for in vivo dosimetry in the kV range. However, some energy-dependent dosimetry effects need to be considered and corrected for. Due to reproducibility effects at low dose levels accurate in vivo measurements are only possible if the applied dose is equal to or larger than 2 Gy.

Application of commercial MOSFET detectors for in vivo dosimetry in the therapeutic x-ray range from 80 kV to 250 kV.

PubMed

Ehringfeld, Christian; Schmid, Susanne; Poljanc, Karin; Kirisits, Christian; Aiginger, Hannes; Georg, Dietmar

2005-01-21

The purpose of this study was to investigate the dosimetric characteristics (energy dependence, linearity, fading, reproducibility, etc) of MOSFET detectors for in vivo dosimetry in the kV x-ray range. The experience of MOSFET in vivo dosimetry in a pre-clinical study using the Alderson phantom and in clinical practice is also reported. All measurements were performed with a Gulmay D3300 kV unit and TN-502RDI MOSFET detectors. For the determination of correction factors different solid phantoms and a calibrated Farmer-type chamber were used. The MOSFET signal was linear with applied dose in the range from 0.2 to 2 Gy for all energies. Due to fading it is recommended to read the MOSFET signal during the first 15 min after irradiation. For long time intervals between irradiation and readout the fading can vary largely with the detector. The temperature dependence of the detector signal was small (0.3% degrees C(-1)) in the temperature range between 22 and 40 degrees C. The variation of the measuring signal with beam incidence amounts to +/-5% and should be considered in clinical applications. Finally, for entrance dose measurements energy-dependent calibration factors, correction factors for field size and irradiated cable length were applied. The overall accuracy, for all measurements, was dominated by reproducibility as a function of applied dose. During the pre-clinical in vivo study, the agreement between MOSFET and TLD measurements was well within 3%. The results of MOSFET measurements, to determine the dosimetric characteristics as well as clinical applications, showed that MOSFET detectors are suitable for in vivo dosimetry in the kV range. However, some energy-dependent dosimetry effects need to be considered and corrected for. Due to reproducibility effects at low dose levels accurate in vivo measurements are only possible if the applied dose is equal to or larger than 2 Gy.

Long-Term Outcome in Pyridoxine-Dependent Epilepsy

ERIC Educational Resources Information Center

Bok, Levinus A.; Halbertsma, Feico J..; Houterman, Saskia; Wevers, Ron A.; Vreeswijk, Charlotte; Jakobs, Cornelis; Struys, Eduard; van der Hoeven, Johan H.; Sival, Deborah A.; Willemsen, Michel A.

2012-01-01

Aim: The long-term outcome of the Dutch pyridoxine-dependent epilepsy cohort and correlations between patient characteristics and follow-up data were retrospectively studied. Method: Fourteen patients recruited from a national reference laboratory were included (four males, 10 females, from 11 families; median age at assessment 6y; range 2y…

Implications of climate change for wetland-dependent birds in the Prairie Pothole Region

USGS Publications Warehouse

Steen, Valerie; Skagen, Susan K.; Melcher, Cynthia P.

2016-01-01

The habitats and food resources required to support breeding and migrant birds dependent on North American prairie wetlands are threatened by impending climate change. The North American Prairie Pothole Region (PPR) hosts nearly 120 species of wetland-dependent birds representing 21 families. Strategic management requires knowledge of avian habitat requirements and assessment of species most vulnerable to future threats. We applied bioclimatic species distribution models (SDMs) to project range changes of 29 wetland-dependent bird species using ensemble modeling techniques, a large number of General Circulation Models (GCMs), and hydrological climate covariates. For the U.S. PPR, mean projected range change, expressed as a proportion of currently occupied range, was −0.31 (± 0.22 SD; range − 0.75 to 0.16), and all but two species were projected to lose habitat. Species associated with deeper water were expected to experience smaller negative impacts of climate change. The magnitude of climate change impacts was somewhat lower in this study than earlier efforts most likely due to use of different focal species, varying methodologies, different modeling decisions, or alternative GCMs. Quantification of the projected species-specific impacts of climate change using species distribution modeling offers valuable information for vulnerability assessments within the conservation planning process.

Study of the Wavelength Dependence in Laser Ablation of Advanced Ceramics and Glass-Ceramic Materials in the Nanosecond Range

PubMed Central

Sola, Daniel; Peña, Jose I.

2013-01-01

In this work, geometrical dimensions and ablation yields as a function of the machining method and reference position were studied when advanced ceramics and glass-ceramic materials were machined with pulsed lasers in the nanosecond range. Two laser systems, emitting at 1064 and 532 nm, were used. It was shown that the features obtained depend on whether the substrate is processed by means of pulse bursts or by grooves. In particular, when the samples were processed by grooves, machined depth, removed volume and ablation yields reached their maximum, placing the sample out of focus. It was shown that these characteristics do not depend on the processing conditions, the wavelength or the optical configuration, and that this is intrinsic behavior of the processing method. Furthermore, the existence of a close relation between material hardness and ablation yields was demonstrated. PMID:28788391

On transitions in the behaviour of tabu search algorithm TabuCol for graph colouring

NASA Astrophysics Data System (ADS)

Chalupa, D.

2018-01-01

Even though tabu search is one of the most popular metaheuristic search strategies, its understanding in terms of behavioural transitions and parameter tuning is still very limited. In this paper, we present a theoretical and experimental study of a popular tabu search algorithm TabuCol for graph colouring. We show that for some instances, there are sharp transitions in the behaviour of TabuCol, depending on the value of tabu tenure parameter. The location of this transition depends on graph structure and may also depend on its size. This is further supported by an experimental study of success rate profiles, which we define as an empirical measure of these transitions. We study the success rate profiles for a range of graph colouring instances, from 2-colouring of trees and forests to several instances from the DIMACS benchmark. These reveal that TabuCol may exhibit a spectrum of different behaviours ranging from simple transitions to highly complex probabilistic behaviour.

Studies on frequency dependent electrical and dielectric properties of sintered zinc oxide pellets: effects of Al-doping

NASA Astrophysics Data System (ADS)

Tewari, S.; Ghosh, A.; Bhattacharjee, A.

2016-11-01

Sintered pellets of zinc oxide (ZnO), both undoped and Al-doped are prepared through a chemical process. Dopant concentration of Aluminium in ZnO [Al/Zn in weight percentage (wt%)] is varied from 0 to 3 wt%. After synthesis structural characterisation of the samples are performed with XRD and SEM-EDAX which confirm that all the samples are of ZnO having polycrystalline nature with particle size from 108.6 to 116 nm. Frequency dependent properties like a.c. conductivity, capacitance, impedance and phase angle are measured in the frequency range 10 Hz to 100 kHz as a function of temperature (in the range 25-150 °C). Nature of a.c. conductivity in these samples indicates hopping type of conduction arising from localised defect states. The frequency and temperature dependent properties under study are found to be as per correlated barrier hoping model. Dielectric and impedance properties studied in the samples indicate distributed relaxation, showing decrease of relaxation time with temperature.

High dose-per-pulse electron beam dosimetry: Usability and dose-rate independence of EBT3 Gafchromic films.

PubMed

Jaccard, Maud; Petersson, Kristoffer; Buchillier, Thierry; Germond, Jean-François; Durán, Maria Teresa; Vozenin, Marie-Catherine; Bourhis, Jean; Bochud, François O; Bailat, Claude

2017-02-01

The aim of this study was to assess the suitability of Gafchromic EBT3 films for reference dose measurements in the beam of a prototype high dose-per-pulse linear accelerator (linac), capable of delivering electron beams with a mean dose-rate (Ḋ m ) ranging from 0.07 to 3000 Gy/s and a dose-rate in pulse (Ḋ p ) of up to 8 × 10 6 Gy/s. To do this, we evaluated the overall uncertainties in EBT3 film dosimetry as well as the energy and dose-rate dependence of their response. Our dosimetric system was composed of EBT3 Gafchromic films in combination with a flatbed scanner and was calibrated against an ionization chamber traceable to primary standard. All sources of uncertainties in EBT3 dosimetry were carefully analyzed using irradiations at a clinical radiotherapy linac. Energy dependence was investigated with the same machine by acquiring and comparing calibration curves for three different beam energies (4, 8 and 12 MeV), for doses between 0.25 and 30 Gy. Ḋ m dependence was studied at the clinical linac by changing the pulse repetition frequency (f) of the beam in order to vary Ḋ m between 0.55 and 4.40 Gy/min, while Ḋ p dependence was probed at the prototype machine for Ḋ p ranging from 7 × 10 3 to 8 × 10 6 Gy/s. Ḋ p dependence was first determined by studying the correlation between the dose measured by films and the charge of electrons measured at the exit of the machine by an induction torus. Furthermore, we compared doses from the films to independently calibrated thermo-luminescent dosimeters (TLD) that have been reported as being dose-rate independent up to such high dose-rates. We report that uncertainty below 4% (k = 2) can be achieved in the dose range between 3 and 17 Gy. Results also demonstrated that EBT3 films did not display any detectable energy dependence for electron beam energies between 4 and 12 MeV. No Ḋ m dependence was found either. In addition, we obtained excellent consistency between films and TLDs over the entire Ḋ p range attainable at the prototype linac confirming the absence of any dose-rate dependence within the investigated range (7 × 10 3 to 8 × 10 6 Gy/s). This aspect was further corroborated by the linear relationship between the dose-per-pulse (D p ) measured by films and the charge per pulse (C p ) measured at the prototype linac exit. Our study shows that the use of EBT3 Gafchromic films can be extended to reference dosimetry in pulsed electron beams with a very high dose rate. The measurement results are associated with an overall uncertainty below 4% (k = 2) and are dose-rate and energy independent. © 2016 American Association of Physicists in Medicine.

A new study of shower age distribution in near vertical showers by EAS air shower array

NASA Technical Reports Server (NTRS)

Chaudhuri, N.; Basak, D. K.; Goswami, G. C.; Ghosh, B.

1984-01-01

The air shower array has been developed since it started operation in 1931. The array covering an area of 900 sq m now incorporates 21 particle density sampling detectors around two muon magnetic spectrographs. The air showers are detected in the size range 10 to the 4th power to 10 to the 6th power particles. A total of 11000 showers has so far been detected. Average values of shower age have been obtained in various shower size ranges to study the dependence of shower age on shower size. The core distance dependence of shower age parameter has also been analyzed for presentation.

A variational data assimilation system for the range dependent acoustic model using the representer method: Theoretical derivations.

PubMed

Ngodock, Hans; Carrier, Matthew; Fabre, Josette; Zingarelli, Robert; Souopgui, Innocent

2017-07-01

This study presents the theoretical framework for variational data assimilation of acoustic pressure observations into an acoustic propagation model, namely, the range dependent acoustic model (RAM). RAM uses the split-step Padé algorithm to solve the parabolic equation. The assimilation consists of minimizing a weighted least squares cost function that includes discrepancies between the model solution and the observations. The minimization process, which uses the principle of variations, requires the derivation of the tangent linear and adjoint models of the RAM. The mathematical derivations are presented here, and, for the sake of brevity, a companion study presents the numerical implementation and results from the assimilation simulated acoustic pressure observations.

Temperature dependent droplet impact dynamics on flat and textured surfaces

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

Azar Alizadeh; Vaibhav Bahadur; Sheng Zhong

Droplet impact dynamics determines the performance of surfaces used in many applications such as anti-icing, condensation, boiling and heat transfer. We study impact dynamics of water droplets on surfaces with chemistry/texture ranging from hydrophilic to superhydrophobic and across a temperature range spanning below freezing to near boiling conditions. Droplet retraction shows very strong temperature dependence especially for hydrophilic surfaces; it is seen that lower substrate temperatures lead to lesser retraction. Physics-based analyses show that the increased viscosity associated with lower temperatures can explain the decreased retraction. The present findings serve to guide further studies of dynamic fluid-structure interaction at variousmore » temperatures.« less

Absolute calibration of a multichannel plate detector for low energy O, O-, and O+

NASA Astrophysics Data System (ADS)

Stephen, T. M.; Peko, B. L.

2000-03-01

Absolute detection efficiencies of a commercial multichannel plate detector have been measured for O, O+, and O-, impacting at normal incidence for energies ranging from 30-1000 eV. In addition, the detection efficiencies for O relative to its ions are presented, as they may have a more universal application. The absolute detection efficiencies are strongly energy dependent and significant differences are observed for the various charge states at lower energies. The detection efficiencies for the different charge states appear to converge at higher energies. The strongest energy dependence is for O+; the detection efficiency varies by three orders of magnitude across the energy range studied. The weakest dependence is for O-, which varies less than one order of magnitude.

Investigation of the Mesostructure of Transition-Metal Monogermanides Synthesized under Pressure

NASA Astrophysics Data System (ADS)

Safiulina, I. A.; Altynbaev, E. V.; Iashina, E. G.; Heinemann, A.; Fomicheva, L. N.; Tsvyashchenko, A. V.; Grigoriev, S. V.

2018-04-01

The mesostructure of transition-metal monogermanides Mn1 - x Co x Ge is studied by small-angle neutron scattering in a wide range of concentrations x = 0-0.95. These compounds were synthesized under high pressure and are metastable under normal conditions. The experimental dependences I( Q) obtained for the whole series of samples in the range of transferred momenta (6 × 10-2 nm-1 < Q< 2.5 nm-1) are described by the power dependence Q - n with an exponent n = 2.99 ± 0.02, uniquely related to the fractal properties of the system under study. The dependence obtained indicates that the superatomic structure of the samples is characterized by the presence of defects with a spatial organization described by a fractal model with a logarithmic dependence of the correlation function of the defect density. It is interesting to note that such defects are absent in the isostructural FeGe compound, i.e., the experimental dependences of the intensity are described well by the expression Q - n with an exponent n = 4.1 ± 0.1, which demonstrates the presence of crystallites with a uniform density distribution inside and a sharp boundary characterizing the surface.

Validation of integrated water vapor from OMI satellite instrument against reference GPS data at the Iberian Peninsula.

PubMed

Vaquero-Martínez, Javier; Antón, Manuel; Ortiz de Galisteo, José Pablo; Cachorro, Victoria E; Wang, Huiqun; González Abad, Gonzalo; Román, Roberto; Costa, Maria João

2017-02-15

This paper shows the validation of integrated water vapor (IWV) measurements retrieved from the Ozone Monitoring Instrument (OMI), using as reference nine ground-based GPS stations in the Iberian Peninsula. The study period covers from 2007 to 2009. The influence of two factors, - solar zenith angle (SZA) and IWV -, on OMI-GPS differences was studied in detail, as well as the seasonal dependence. The pseudomedian of the relative differences is -1 ± 1% and the inter-quartile range (IQR) is 41%. Linear regressions calculated over each station show an acceptable agreement (R 2 up to 0.77). The OMI-GPS differences display a clear dependence on IWV values. Hence, OMI substantially overestimates the lower IWV data recorded by GPS (∼ 40%), while underestimates the higher IWV reference values (∼ 20%). In connection to this IWV dependence, the relative differences also show an evident SZA dependence when the whole range of IWV values are analyzed (OMI overestimates for high SZA values while underestimates for low values). Finally, the seasonal variation of the OMI-GPS differences is also associated with the strong IWV dependence found in this validation exercise. Copyright © 2016 Elsevier B.V. All rights reserved.

Smart Swarms of Bacteria-Inspired Agents with Performance Adaptable Interactions

PubMed Central

Shklarsh, Adi; Ariel, Gil; Schneidman, Elad; Ben-Jacob, Eshel

2011-01-01

Collective navigation and swarming have been studied in animal groups, such as fish schools, bird flocks, bacteria, and slime molds. Computer modeling has shown that collective behavior of simple agents can result from simple interactions between the agents, which include short range repulsion, intermediate range alignment, and long range attraction. Here we study collective navigation of bacteria-inspired smart agents in complex terrains, with adaptive interactions that depend on performance. More specifically, each agent adjusts its interactions with the other agents according to its local environment – by decreasing the peers' influence while navigating in a beneficial direction, and increasing it otherwise. We show that inclusion of such performance dependent adaptable interactions significantly improves the collective swarming performance, leading to highly efficient navigation, especially in complex terrains. Notably, to afford such adaptable interactions, each modeled agent requires only simple computational capabilities with short-term memory, which can easily be implemented in simple swarming robots. PMID:21980274

Smart swarms of bacteria-inspired agents with performance adaptable interactions.

PubMed

Shklarsh, Adi; Ariel, Gil; Schneidman, Elad; Ben-Jacob, Eshel

2011-09-01

Collective navigation and swarming have been studied in animal groups, such as fish schools, bird flocks, bacteria, and slime molds. Computer modeling has shown that collective behavior of simple agents can result from simple interactions between the agents, which include short range repulsion, intermediate range alignment, and long range attraction. Here we study collective navigation of bacteria-inspired smart agents in complex terrains, with adaptive interactions that depend on performance. More specifically, each agent adjusts its interactions with the other agents according to its local environment--by decreasing the peers' influence while navigating in a beneficial direction, and increasing it otherwise. We show that inclusion of such performance dependent adaptable interactions significantly improves the collective swarming performance, leading to highly efficient navigation, especially in complex terrains. Notably, to afford such adaptable interactions, each modeled agent requires only simple computational capabilities with short-term memory, which can easily be implemented in simple swarming robots.

The relation between the quantum discord and quantum teleportation: The physical interpretation of the transition point between different quantum discord decay regimes

NASA Astrophysics Data System (ADS)

Roszak, K.; Cywiński, Ł.

2015-10-01

We study quantum teleportation via Bell-diagonal mixed states of two qubits in the context of the intrinsic properties of the quantum discord. We show that when the quantum-correlated state of the two qubits is used for quantum teleportation, the character of the teleportation efficiency changes substantially depending on the Bell-diagonal-state parameters, which can be seen when the worst-case-scenario or best-case-scenario fidelity is studied. Depending on the parameter range, one of two types of single-qubit states is hardest/easiest to teleport. The transition between these two parameter ranges coincides exactly with the transition between the range of classical correlation decay and quantum correlation decay characteristic for the evolution of the quantum discord. The correspondence provides a physical interpretation for the prominent feature of the decay of the quantum discord.

Range-dependence of acoustic channel with traveling sinusoidal surface wave.

PubMed

Choo, Youngmin; Seong, Woojae; Lee, Keunhwa

2014-04-01

Range-dependence of time-varying acoustic channels caused by a traveling surface wave is investigated through water tank experiments and acoustic propagation analysis schemes. As the surface wave travels, surface reflected signals fluctuate and the fluctuation varies with source-receiver horizontal range. Amplitude fluctuations of surface reflected signals increase with increasing horizontal range whereas the opposite occurs in delay fluctuations. The scattered pressure field at a fixed time shows strong dependence on the receiver position because of caustics and shadow zones formed by the surface. The Doppler shifts of surface reflected signals also depend on the horizontal range. Comparison between measurement data and model results indicates the Doppler shift relies on the delay fluctuation under current experimental conditions.

C-Phycocyanin Hydration Water Dynamics in the Presence of Trehalose: An Incoherent Elastic Neutron Scattering Study at Different Energy Resolutions

PubMed Central

Gabel, Frank; Bellissent-Funel, Marie-Claire

2007-01-01

We present a study of C-phycocyanin hydration water dynamics in the presence of trehalose by incoherent elastic neutron scattering. By combining data from two backscattering spectrometers with a 10-fold difference in energy resolution we extract a scattering law S(Q,ω) from the Q-dependence of the elastic intensities without sampling the quasielastic range. The hydration water is described by two dynamically different populations—one diffusing inside a sphere and the other diffusing quasifreely—with a population ratio that depends on temperature. The scattering law derived describes the experimental data from both instruments excellently over a large temperature range (235–320 K). The effective diffusion coefficient extracted is reduced by a factor of 10–15 with respect to bulk water at corresponding temperatures. Our approach demonstrates the benefits and the efficiency of using different energy resolutions in incoherent elastic neutron scattering over a large angular range for the study of biological macromolecules and hydration water. PMID:17350998

Pressure Dependence of the Boson Peak of Glassy Glycerol

DOE PAGES

Ahart, Muhtar; Aihaiti, Dilare; Hemley, Russell J.; ...

2017-05-31

The pressure dependence of the Boson peak (BP) of glycerol, including its behavior across the liquid-glass transition, has been studied under pressure using Raman scattering. A significant increase of the BP frequency was observed with pressure up to 11 GPa at room temperature. The pressure dependence of BP frequency ν BP is proportional to (1+P/P 0) 1/3, where P and P 0 are the pressure and a constant, respectively, the spectra are consistent with a soft potential model. The characteristic length of medium range order is close in size to a cyclic trimer of glycerol molecules, which is predicted asmore » the medium range order of a BP vibration using molecular dynamics simulations. The pressure dependence of a characteristic length of medium range order is nearly constant. The pressure induced structural changes in glycerol can be understood in terms of the shrinkage of voids with cyclic trimers remaining up to at least 11 GPa. Lastly, the pressure dependence of intermolecular O-H stretching mode indicates that the intermolecular hydrogen bond distance gradually decreases below the glass transition pressure of ~5 GPa, while it becomes nearly constant in the glassy state indicating the disappearance of the free volume in the dense glass.« less

Association of EEG alpha variants and alpha power with alcohol dependence in Mexican American young adults.

PubMed

Ehlers, Cindy L; Phillips, Evelyn

2007-02-01

Several studies support an association between electroencephalogram (EEG) voltage and alcohol dependence. However, the distribution of EEG variants also appears to differ depending on an individual's ethnic heritage, suggesting significant genetic stratification of this EEG phenotype. The present study's aims were to investigate the incidence of EEG alpha variants and spectral power in the alpha frequency range in Mexican American young adults based on gender, and personal and family history of alcohol dependence. Clinical ratings (high-, medium-, and low alpha voltage variants) and spectral characteristics of the EEG in the alpha frequency range (7.5-12 Hz) were investigated in young adult (age 18-25 years) Mexican American men (n=98) and women (n=138) who were recruited from the community. Nineteen percent (n=45) of the participants had a low-voltage alpha EEG variant, 18% had a high-voltage variant, and 63% had a medium-voltage variant. There were no significant differences in the distribution of the EEG variants based on family history of alcohol dependence. There was a significant relationship between gender and the three alpha variants (chi2=9.7; df=2; P<.008), and there were no male participants with alcohol dependence with high alpha variants (chi2=5.8; df=2; P<.056). Alcohol dependence, but not a family history of alcohol dependence, was associated with lower spectral power in the alpha frequency range in the right (F=4.4; df=1,96; P<.04) and left (F=5.3; df=1.96; P<.02) occipital areas in the men but not in the women. In conclusion, in this select population of Mexican American young adults, male gender and alcohol dependence are associated with an absence of high-voltage alpha variants and lower alpha power in the EEG. These data suggest that EEG low voltage, a highly heritable trait, may represent an important endophenotype in male Mexican Americans that may aid in linking brain function with genetic factors underlying alcohol dependence in this ethnic group.

Localized surface plasmon resonance nanosensor: a high-resolution distance-dependence study using atomic layer deposition.

PubMed

Whitney, Alyson V; Elam, Jeffrey W; Zou, Shengli; Zinovev, Alex V; Stair, Peter C; Schatz, George C; Van Duyne, Richard P

2005-11-03

Atomic layer deposition (ALD) is used to deposit 1-600 monolayers of Al(2)O(3) on Ag nanotriangles fabricated by nanosphere lithography (NSL). Each monolayer of Al(2)O(3) has a thickness of 1.1 A. It is demonstrated that the localized surface plasmon resonance (LSPR) nanosensor can detect Al(2)O(3) film growth with atomic spatial resolution normal to the nanoparticle surface. This is approximately 10 times greater spatial resolution than that in our previous long-range distance-dependence study using multilayer self-assembled monolayer shells. The use of ALD enables the study of both the long- and short-range distance dependence of the LSPR nanosensor in a single unified experiment. Ag nanoparticles with fixed in-plane widths and decreasing heights yield larger sensing distances. X-ray photoelectron spectroscopy, variable angle spectroscopic ellipsometry, and quartz crystal microbalance measurements are used to study the growth mechanism. It is proposed that the growth of Al(2)O(3) is initiated by the decomposition of trimethylaluminum on Ag. Semiquantitative theoretical calculations were compared with the experimental results and yield excellent agreement.

Dielectric relaxation in complex perovskite oxide In(Ni{sub 1/2}Zr{sub 1/2})O{sub 3}

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

Agrawal, Lata, E-mail: lata_agrawal84@yahoo.com; Singh, B.P.; Sinha, T.P.

2009-09-15

The dielectric study of indium nickel zirconate, In(Ni{sub 1/2}Zr{sub 1/2})O{sub 3} (INZ) synthesized by solid state reaction technique is performed in a frequency range from 500 Hz to 1 MHz and in a temperature range from 303 to 493 K. The X-ray diffraction analysis shows that the compound is monoclinic. A relaxation is observed in the entire temperature range as a gradual decrease in {epsilon}'({omega}) and as a broad peak in {epsilon}''({omega}) in the frequency dependent real and imaginary parts of dielectric constant, respectively. The frequency dependent electrical data are analyzed in the framework of conductivity and electric modulus formalisms.more » The frequencies corresponding to the maxima of the imaginary electric modulus at various temperatures are found to obey an Arrhenius law with activation energy of 0.66 eV. The Cole-Cole model is used to study the dielectric relaxation of INZ. The scaling behaviour of imaginary part of electric modulus suggests that the relaxation describes the same mechanism at various temperatures. The frequency dependent conductivity spectra follow the universal power law.« less

Temperature dependence of piezoelectric properties for textured SBN ceramics.

PubMed

Kimura, Masahiko; Ogawa, Hirozumi; Kuroda, Daisuke; Sawada, Takuya; Higuchi, Yukio; Takagi, Hiroshi; Sakabe, Yukio

2007-12-01

Temperature dependences of piezoelectric properties were studied for h001i textured ceramics of bismuth layer-structured ferroelectrics, SrBi(2)Nb(2)O(9) (SBN). The textured ceramics with varied orientation degrees were fabricated by templated, grain-growth method, and the temperature dependences of resonance frequency were estimated. Excellent temperature stability of resonance frequency was obtained for the 76% textured ceramics. The resonance frequency of the 76% textured specimens varied almost linearly over a wide temperature range. Therefore, the variation was slight, even in a high temperature region above 150 degrees C. Temperature stability of a quartz crystal oscillator is generally higher than that of a ceramic resonator around room temperature. The variation of resonance frequency for the 76% textured SrBi(2)Nb(2)O(9) was larger than that of oscillation frequency for a typical quartz oscillator below 150 degrees C also in this study. However, the variation of the textured SrBi(2)Nb(2)O(9) was smaller than that of the quartz oscillator over a wide temperature range from -50 to 250 degrees C. Therefore, textured SrBi(2)Nb(2)O(9) ceramics is a major candidate material for the resonators used within a wide temperature range.

Dosimetric characteristics of a MOSFET dosimeter for clinical electron beams.

PubMed

Manigandan, D; Bharanidharan, G; Aruna, P; Devan, K; Elangovan, D; Patil, Vikram; Tamilarasan, R; Vasanthan, S; Ganesan, S

2009-09-01

The fundamental dosimetric characteristics of commercially available metal oxide semiconductor field effect transistor (MOSFET) detectors were studied for clinical electron beam irradiations. MOSFET showed excellent linearity against doses measured using an ion chamber in the dose range of 20-630cGy. MOSFET reproducibility is better at high doses compared to low doses. The output factors measured with the MOSFET were within +/-3% when compared with those measured with a parallel plate chamber. From 4 to 12MeV, MOSFETs showed a large angular dependence in the tilt directions and less in the axial directions. MOSFETs do not show any dose-rate dependence between 100 and 600MU/min. However, MOSFETs have shown under-response when the dose per pulse of the beam is decreased. No measurable effect in MOSFET response was observed in the temperature range of 23-40 degrees C. The energy dependence of a MOSFET dosimeter was within +/-3.0% for 6-18MeV electron beams and 5.5% for 4MeV ones. This study shows that MOSFET detectors are suitable for dosimetry of electron beams in the energy range of 4-18MeV.

Age-dependent changes in ecosystem carbon fluxes in managed forests in Northern Wisconsin, USA

Treesearch

Asko Noormets; Jiquan Chen; Thomas R. Crow

2007-01-01

The age-dependent variability of ecosystem carbon (C) fluxes was assessed by measuring the net ecosystem exchange of C (NEE) in five managed forest stands in northern Wisconsin, USA. The study sites ranged in age from 3-year-old clearcut to mature stands (65 years). All stands, except the clearcut, accumulated C over the study period from May to October 2002. Seasonal...

Psychometric properties of the List of Threatening Experiences--LTE and its association with psychosocial factors and mental disorders according to different scoring methods.

PubMed

Motrico, Emma; Moreno-Küstner, Berta; de Dios Luna, Juan; Torres-González, Francisco; King, Michael; Nazareth, Irwin; Montón-Franco, Carmen; Gilde Gómez-Barragán, María Josefa; Sánchez-Celaya, Marta; Díaz-Barreiros, Miguel Ángel; Vicens, Catalina; Moreno-Peral, Patricia; Bellón, Juan Ángel

2013-09-25

The List of Threatening Experiences (LTE) questionnaire is frequently used to assess stressful events; however, studies of its psychometric properties are scarce. We examined the LTE's reliability, factorial structure, construct validity and explored the association between LTE scores and psychosocial variables and mental disorders. This study involved interviewing 5442 primary care attendees from Spain. Associations between four different methods of quantifying LTE scores, psychosocial factors, major depression (CIDI), anxiety disorders (PRIME-MD), alcohol misuse and dependence (AUDIT) were measured. The LTE showed high test-retest reliability (Kappa range=0.61-0.87) and low internal consistency (α=0.44). Tetrachoric factorial analysis yielded four factors (spousal and relational problems; employment and financial problems; personal problems; illness and bereavement in close persons). Logistic multilevel regression found a strong association between greater social support and a lower occurrence of stressful events (OR range=0.36-0.79). The association between religious-spiritual beliefs and the LTE, was weaker. The association between mental disorders and LTE scores was greater for depression (OR range=1.64-2.57) than anxiety (OR range=1.35-1.97), though the highest ORs were obtained with alcohol dependence (OR range=2.86-4.80). The ordinal score (ordinal regression) was more sensitive to detect the strength of association with mental disorders. We are unable to distinguish the direction of the association between stressful events, psychosocial factors and mental disorders, due to our cross-sectional design of the study. The LTE is a valid and reliable measure of stress in mental health, and the strength of association with mental disorders depends on the method of quantifying LTE scores. © 2013 Elsevier B.V. All rights reserved.

An integrate-and-fire model to generate spike trains with long-range dependence.

PubMed

Richard, Alexandre; Orio, Patricio; Tanré, Etienne

2018-06-01

Long-range dependence (LRD) has been observed in a variety of phenomena in nature, and for several years also in the spiking activity of neurons. Often, this is interpreted as originating from a non-Markovian system. Here we show that a purely Markovian integrate-and-fire (IF) model, with a noisy slow adaptation term, can generate interspike intervals (ISIs) that appear as having LRD. However a proper analysis shows that this is not the case asymptotically. For comparison, we also consider a new model of individual IF neuron with fractional (non-Markovian) noise. The correlations of its spike trains are studied and proven to have LRD, unlike classical IF models. On the other hand, to correctly measure long-range dependence, it is usually necessary to know if the data are stationary. Thus, a methodology to evaluate stationarity of the ISIs is presented and applied to the various IF models. We explain that Markovian IF models may seem to have LRD because of non-stationarities.

Updates to WFC3/UVIS Filter-Dependent and Filter-Distinct Distortion Corrections

NASA Astrophysics Data System (ADS)

Martlin, Catherine; Kozhurina-Platais, Vera; McKay, Myles; Sabbi, Elena

2018-06-01

The WFC3/UVIS filter wheel contains 63 filters that cover a large range of wavelengths from near ultraviolet to the near infrared. Previously, analysis was completed on the 14 most used UVIS filters to calibrate geometric distortions. These distortions are due to a combination of the optical assembly of HST as well as the variabilities in the composition of individual filters. We report recent updates to reference files that aid in correcting for these distortions of an additional 22 UVIS narrow and medium band filters and 4 unique UVIS filters. They were created following a calibration of the large-scale optical distortions and fine-scale filter-dependent distortions. Furthermore, we present results on a study into a selection of unique polynomial coefficient terms from all solved filters which allows us to better investigate the filter-dependent patterns across a large range of wavelengths.These updates will provide important enhancements for HST/WFC3 users as they allow more accurate alignment of images across the range of UVIS filters.

Wavelength dependence of nanosecond laser induced surface damage in fused silica from 260 to 1550 nm

NASA Astrophysics Data System (ADS)

Cao, Ming; Cao, Jianjun; Liu, Mian; Sun, Yuan; Wu, Meng; Guo, Shiming; Gao, Shumei

2018-04-01

The wavelength dependence of laser induced surface damage in fused silica is experimentally studied in a wide wavelength range from 260 to 1550 nm. An optical parametric oscillator system is used to provide the tunable laser pulses with a duration of 5 ns. In the experiments, the exit surface of the silica slice is observed to be damaged prior to the entrance surface. The damage threshold decreases gradually as the wavelength decreases from 1550 to 324 nm and drops suddenly at 324 nm, which corresponds to a half of 7.66 eV. This wavelength dependence can be explained by a defect assisted multiphoton absorption mechanism. By fitting the experimental data with a power law equation, the damage threshold is found to be proportional to the 3.47-th power of wavelength in the range of 325-685 nm and 1.1-th power of wavelength in the range of 260-1550 nm.

Risk of substance abuse and dependence among young adult sexual minority groups using a multidimensional measure of sexual orientation.

PubMed

Goldberg, Shoshana; Strutz, Kelly L; Herring, Amy A; Halpern, Carolyn T

2013-01-01

We examined associations between two definitions of sexual minority status (SMS) and substance abuse and/or dependence among young adults in a national population. A total of 14,152 respondents (7,529 women and 6,623 men) interviewed during wave four of the National Longitudinal Study of Adolescent Health were included in the study (age range: 24-32 years). We used two definitions of SMS based on self-reported attraction, behavior, and identity: 1-indicator SMS (endorsing any dimension) and 3-indicator SMS (endorsing all dimensions). Outcomes included nicotine dependence as well as ≥3 signs of substance dependence, any sign of substance abuse, and lifetime diagnosis of abuse or dependence for alcohol, marijuana, and a composite measure of other drugs. Weighted logistic regression models were fit to estimate the odds of each outcome for each of the sexual minority groups (compared with the heterosexual majority), controlling for sociodemographic covariates. SMS women were more likely than exclusively heterosexual women to experience substance abuse and dependence, regardless of substance or SMS definition. In adjusted models for women, 3-indicator SMS was most strongly associated with abuse/dependence (adjusted odds ratio [AOR] range: 2.74-5.17) except for ≥3 signs of cannabis dependence, where 1-indicator SMS had the strongest association (AOR=3.35). For men, the 1-indicator SMS group had higher odds of nicotine dependence (AOR=1.35) and the 3-indicator SMS group had higher odds of ≥3 signs of alcohol dependence (AOR=1.64). Young adult female sexual minority groups, regardless of how defined, are at a higher risk than their heterosexual peers of developing alcohol, drug, or tobacco abuse and dependence.

Apparent critical thickness versus temperature for InAs quantum dot growth on GaAs(001)

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

Patella, F.; Arciprete, F.; Fanfoni, M.

2006-04-17

We studied the temperature dependence of the two-dimensional to three-dimensional growth transition in InAs/GaAs(001) heteroepitaxy by means of reflection high energy electron diffraction and atomic force microscopy. The observed shift of the transition to higher InAs deposition times, at temperatures above 500 deg. C, is not a change of critical thickness for islanding, which instead, is constant in the 450-560 deg. C range. Consequently, In-Ga intermixing and surface and interface strain have a negligible dependence on temperature in this range.

X-ray absorption in insulators with non-Hermitian real-time time-dependent density functional theory.

PubMed

Fernando, Ranelka G; Balhoff, Mary C; Lopata, Kenneth

2015-02-10

Non-Hermitian real-time time-dependent density functional theory was used to compute the Si L-edge X-ray absorption spectrum of α-quartz using an embedded finite cluster model and atom-centered basis sets. Using tuned range-separated functionals and molecular orbital-based imaginary absorbing potentials, the excited states spanning the pre-edge to ∼20 eV above the ionization edge were obtained in good agreement with experimental data. This approach is generalizable to TDDFT studies of core-level spectroscopy and dynamics in a wide range of materials.

Improving Limits on Exotic Spin Dependent Long Range Forces using Double Boson Exchange

NASA Astrophysics Data System (ADS)

Aldaihan, Sheakha; Snow, William Michael; Krause, Dennis; Long, Joshua

2016-03-01

The existence of very light weakly interacting particles that mediate new long range forces has been suggested in many extensions of the Standard Model. Such particles span a length scale between a μm and a few meters and include axions, familons, Majorons,and arions. Parameterizations of forces in this range show that they are composite-dependent, have a Yukawa shape, and have both spin-dependent as well as spin independent components. Very stringent limits on spin-independent couplings exist. For long range spin dependent forces, limits are weaker by 20 orders of magnitude compared to their spin independent analogs. The disparity in the limits raises the question of whether interesting limits on spin dependent couplings can be inferred from spin independent searches for long range forces. We show that this is possible using higher order contributions corresponding to double boson exchange and report the limits placed on spin dependent couplings using this method. We gratefully acknowledge the support of Indiana University and the National Science Foundation. The first author also acknowdges King Abdullah scholarship program.

Range-Dependent Acoustic Propagation in Shallow Water with Elastic Bottom Effects

DTIC Science & Technology

2015-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Range-Dependent Acoustic Propagation in Shallow Water ...theory is inadequate for properly describing loss in shallow water acoustic propagation. Finally there is range dependence, which can be significant in...work will lead to a practical method to investigate seismo- acoustic propagation in shallow - water environments, and allow us to compare and contrast

Impedance Spectrum in Cortical Tissue: Implications for Propagation of LFP Signals on the Microscopic Level

PubMed Central

Miceli, Stéphanie

2017-01-01

Brain research investigating electrical activity within neural tissue is producing an increasing amount of physiological data including local field potentials (LFPs) obtained via extracellular in vivo and in vitro recordings. In order to correctly interpret such electrophysiological data, it is vital to adequately understand the electrical properties of neural tissue itself. An ongoing controversy in the field of neuroscience is whether such frequency-dependent effects bias LFP recordings and affect the proper interpretation of the signal. On macroscopic scales and with large injected currents, previous studies have found various grades of frequency dependence of cortical tissue, ranging from negligible to strong, within the frequency band typically considered relevant for neuroscience (less than a few thousand hertz). Here, we performed a detailed investigation of the frequency dependence of the conductivity within cortical tissue at microscopic distances using small current amplitudes within the typical (neuro)physiological micrometer and sub-nanoampere range. We investigated the propagation of LFPs, induced by extracellular electrical current injections via patch-pipettes, in acute rat brain slice preparations containing the somatosensory cortex in vitro using multielectrode arrays. Based on our data, we determined the cortical tissue conductivity over a 100-fold increase in signal frequency (5–500 Hz). Our results imply at most very weak frequency-dependent effects within the frequency range of physiological LFPs. Using biophysical modeling, we estimated the impact of different putative impedance spectra. Our results indicate that frequency dependencies of the order measured here and in most other studies have negligible impact on the typical analysis and modeling of LFP signals from extracellular brain recordings. PMID:28197543

Impedance Spectrum in Cortical Tissue: Implications for Propagation of LFP Signals on the Microscopic Level.

PubMed

Miceli, Stéphanie; Ness, Torbjørn V; Einevoll, Gaute T; Schubert, Dirk

2017-01-01

Brain research investigating electrical activity within neural tissue is producing an increasing amount of physiological data including local field potentials (LFPs) obtained via extracellular in vivo and in vitro recordings. In order to correctly interpret such electrophysiological data, it is vital to adequately understand the electrical properties of neural tissue itself. An ongoing controversy in the field of neuroscience is whether such frequency-dependent effects bias LFP recordings and affect the proper interpretation of the signal. On macroscopic scales and with large injected currents, previous studies have found various grades of frequency dependence of cortical tissue, ranging from negligible to strong, within the frequency band typically considered relevant for neuroscience (less than a few thousand hertz). Here, we performed a detailed investigation of the frequency dependence of the conductivity within cortical tissue at microscopic distances using small current amplitudes within the typical (neuro)physiological micrometer and sub-nanoampere range. We investigated the propagation of LFPs, induced by extracellular electrical current injections via patch-pipettes, in acute rat brain slice preparations containing the somatosensory cortex in vitro using multielectrode arrays. Based on our data, we determined the cortical tissue conductivity over a 100-fold increase in signal frequency (5-500 Hz). Our results imply at most very weak frequency-dependent effects within the frequency range of physiological LFPs. Using biophysical modeling, we estimated the impact of different putative impedance spectra. Our results indicate that frequency dependencies of the order measured here and in most other studies have negligible impact on the typical analysis and modeling of LFP signals from extracellular brain recordings.

Electronic transport mechanism in intrinsic and doped nanocrystalline silicon films deposited by RF-magnetron sputtering at low temperature

NASA Astrophysics Data System (ADS)

Benlakehal, D.; Belfedal, A.; Bouizem, Y.; Sib, J. D.; Chahed, L.; Zellama, K.

2016-12-01

The dependence on the temperature range, T, of the electronic transport mechanism in intrinsic and doped hydrogenated nanocrystalline silicon films, deposited by radiofrequency-magnetron sputtering at low substrate temperature, has been studied. Electrical conductivity measurements σ(T) have been conducted on these films, as a function of temperature, in the 93-450 K range. The analysis of these results clearly shows a thermally activated conduction process in the 273-450 K range which allows us to estimate the associated activation energy as well as the preexponential conductivity factor. While, in the lower temperature range (T < 273 K), a non-ohmic behavior is observed for the conductivity changes. The conductivity σ(T) presents a linear dependence on (T-1/4) , and a hopping mechanism is suggested to explain these results. By using the Percolation theory, further information can be gained about the density of states near the Fermi level as well as the range and the hopping energy.

Lung and chest wall impedances in the dog in normal range of breathing: effects of pulmonary edema.

PubMed

Barnas, G M; Stamenović, D; Lutchen, K R

1992-09-01

We evaluated the effect of pulmonary edema on the frequency (f) and tidal volume (VT) dependences of respiratory system mechanical properties in the normal ranges of breathing. We measured resistance and elastance of the lungs (RL and EL) and chest wall of four anesthetized-paralyzed dogs during sinusoidal volume oscillations at the trachea (50-300 ml, 0.2-2 Hz), delivered at a constant mean airway pressure. Measurements were made before and after severe pulmonary edema was produced by injection of 0.06 ml/kg oleic acid into the right atrium. Chest wall properties were not changed by the injection. Before oleic acid, EL increased slightly with increasing f in each dog but was independent of VT. RL decreased slightly and was independent of VT from 0.2 to 0.4 Hz, but above 0.4 Hz it tended to increase with increasing flow, presumably due to the airway contribution. After oleic acid injection, EL and RL increased greatly. Large negative dependences of EL on VT and of RL on f were also evident, so that EL and RL after oleic acid changed two- and fivefold, respectively, within the ranges of f and VT studied. We conclude that severe pulmonary edema changes lung properties so as to make behavior VT dependent (i.e., nonlinear) and very frequency dependent in the normal range of breathing.

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

Ahart, Muhtar; Aihaiti, Dilare; Hemley, Russell J.

The pressure dependence of the Boson peak (BP) of glycerol, including its behavior across the liquid-glass transition, has been studied under pressure using Raman scattering. A significant increase of the BP frequency was observed with pressure up to 11 GPa at room temperature. The pressure dependence of BP frequency ν BP is proportional to (1+P/P 0) 1/3, where P and P 0 are the pressure and a constant, respectively, the spectra are consistent with a soft potential model. The characteristic length of medium range order is close in size to a cyclic trimer of glycerol molecules, which is predicted asmore » the medium range order of a BP vibration using molecular dynamics simulations. The pressure dependence of a characteristic length of medium range order is nearly constant. The pressure induced structural changes in glycerol can be understood in terms of the shrinkage of voids with cyclic trimers remaining up to at least 11 GPa. Lastly, the pressure dependence of intermolecular O-H stretching mode indicates that the intermolecular hydrogen bond distance gradually decreases below the glass transition pressure of ~5 GPa, while it becomes nearly constant in the glassy state indicating the disappearance of the free volume in the dense glass.« less

Fractality Evidence and Long-Range Dependence on Capital Markets: a Hurst Exponent Evaluation

NASA Astrophysics Data System (ADS)

Oprean, Camelia; Tănăsescu, Cristina

2014-07-01

Since the existence of market memory could implicate the rejection of the efficient market hypothesis, the aim of this paper is to find any evidence that selected emergent capital markets (eight European and BRIC markets, namely Hungary, Romania, Estonia, Czech Republic, Brazil, Russia, India and China) evince long-range dependence or the random walk hypothesis. In this paper, the Hurst exponent as calculated by R/S fractal analysis and Detrended Fluctuation Analysis is our measure of long-range dependence in the series. The results reinforce our previous findings and suggest that if stock returns present long-range dependence, the random walk hypothesis is not valid anymore and neither is the market efficiency hypothesis.

Static and sliding contact of rough surfaces: Effect of asperity-scale properties and long-range elastic interactions

NASA Astrophysics Data System (ADS)

Hulikal, Srivatsan; Lapusta, Nadia; Bhattacharya, Kaushik

2018-07-01

Friction in static and sliding contact of rough surfaces is important in numerous physical phenomena. We seek to understand macroscopically observed static and sliding contact behavior as the collective response of a large number of microscopic asperities. To that end, we build on Hulikal et al. (2015) and develop an efficient numerical framework that can be used to investigate how the macroscopic response of multiple frictional contacts depends on long-range elastic interactions, different constitutive assumptions about the deforming contacts and their local shear resistance, and surface roughness. We approximate the contact between two rough surfaces as that between a regular array of discrete deformable elements attached to a elastic block and a rigid rough surface. The deformable elements are viscoelastic or elasto/viscoplastic with a range of relaxation times, and the elastic interaction between contacts is long-range. We find that the model reproduces the main macroscopic features of evolution of contact and friction for a range of constitutive models of the elements, suggesting that macroscopic frictional response is robust with respect to the microscopic behavior. Viscoelasticity/viscoplasticity contributes to the increase of friction with contact time and leads to a subtle history dependence. Interestingly, long-range elastic interactions only change the results quantitatively compared to the meanfield response. The developed numerical framework can be used to study how specific observed macroscopic behavior depends on the microscale assumptions. For example, we find that sustained increase in the static friction coefficient during long hold times suggests viscoelastic response of the underlying material with multiple relaxation time scales. We also find that the experimentally observed proportionality of the direct effect in velocity jump experiments to the logarithm of the velocity jump points to a complex material-dependent shear resistance at the microscale.

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

Chen, C.; Albergo, S.; Caccia, Z.

A liquid hydrogen target was used to study the nuclear fragmentation of beams of relativistic heavy ions, [sup 22]Ne to [sup 58]Ni, over an energy range 400 to 900 MeV/nucleon. The experiments were carried out at the Lawrence Berkeley Laboratory Bevalac HISS facility, using the charge-velocity-rigidity method to identify the charged fragments. Here we describe the general concept of the experiment and present total charge-changing cross sections obtained from 17 separate runs. These new measured cross sections display an energy dependence which follows semiempirical model predictions. The mass dependence of the cross sections behaves as predicted by optical models, butmore » within the experimental energy range, the optical model parameters display a clear energy dependence. The isospin of the projectile nuclei also appears to be an important factor in the interaction process.« less

Dielectric Properties of Marsh Vegetation in a Frequency Range of 0.1-18 GHz Under Variation of Temperature and Moisture

NASA Astrophysics Data System (ADS)

Romanov, A. N.; Kochetkova, T. D.; Suslyaev, V. I.; Shcheglova, A. S.

2017-09-01

Dielectric characteristics of some species of marsh vegetation: lichen Cladonia stellaris (Opiz) Pouzar, moss Sphagnum, and a representative of Bryidae mosses - Dicranum polysetum are studied in the frequency range from 100 MHz to 18 GHz. At a frequency of 1.41 GHz, the influence of temperature in the range from -12 to +20°C on the behavior of dielectric characteristics of mosses, lichens, and peat is studied. The dependences of the dielectric characteristics of vegetation on the volumetric wetness are established.

Kinetics of the reaction of Cl atoms with CHCl 3 over the temperature range 253-313 K

NASA Astrophysics Data System (ADS)

Nilsson, Elna J. K.; Hoff, Janus; Nielsen, Ole John; Johnson, Matthew S.

2010-07-01

The reaction CHCl 3 + Cl → CCl 3 + HCl was studied in the atmospherically relevant temperature range from 253 to 313 K and in 930 mbar of N 2 diluent using the relative rate method. A temperature dependent reaction rate constant, valid in the temperature range 220-330 K, was determined by a fit to the result of the present study and that of Orlando (1999); k = (3.77 ± 0.32) × 10 -12 exp((-1011 ± 24)/T) cm 3 molecule -1 s -1.

Chemical Reactions in Turbulent Mixing Flows

DTIC Science & Technology

1989-06-01

combustion to be studied over a range of pressures of 0.1 atm < po < 10atm, permitting a range of two decades of Reynolds number to be covered. Depending on ...The effects of heat release were studied in a planar, gaseous reacting mixing layer formed between two sub- sonic freestreams; one containing hydrogen...and the Reynolds number study of Mungal et al (1985). The issue of heat release effects on the flow was specifically addressed elsewhere (see

Beyond the Young-Laplace model for cluster growth during dewetting of thin films: effective coarsening exponents and the role of long range dewetting interactions.

PubMed

Constantinescu, Adi; Golubović, Leonardo; Levandovsky, Artem

2013-09-01

Long range dewetting forces acting across thin films, such as the fundamental van der Waals interactions, may drive the formation of large clusters (tall multilayer islands) and pits, observed in thin films of diverse materials such as polymers, liquid crystals, and metals. In this study we further develop the methodology of the nonequilibrium statistical mechanics of thin films coarsening within continuum interface dynamics model incorporating long range dewetting interactions. The theoretical test bench model considered here is a generalization of the classical Mullins model for the dynamics of solid film surfaces. By analytic arguments and simulations of the model, we study the coarsening growth laws of clusters formed in thin films due to the dewetting interactions. The ultimate cluster growth scaling laws at long times are strongly universal: Short and long range dewetting interactions yield the same coarsening exponents. However, long range dewetting interactions, such as the van der Waals forces, introduce a distinct long lasting early time scaling behavior characterized by a slow growth of the cluster height/lateral size aspect ratio (i.e., a time-dependent Young angle) and by effective coarsening exponents that depend on cluster size. In this study, we develop a theory capable of analytically calculating these effective size-dependent coarsening exponents characterizing the cluster growth in the early time regime. Such a pronounced early time scaling behavior has been indeed seen in experiments; however, its physical origin has remained elusive to this date. Our theory attributes these observed phenomena to ubiquitous long range dewetting interactions acting across thin solid and liquid films. Our results are also applicable to cluster growth in initially very thin fluid films, formed by depositing a few monolayers or by a submonolayer deposition. Under this condition, the dominant coarsening mechanism is diffusive intercluster mass transport while the cluster coalescence plays a minor role, both in solid and in fluid films.

Immigration Rates during Population Density Reduction in a Coral Reef Fish

PubMed Central

Turgeon, Katrine; Kramer, Donald L.

2016-01-01

Although the importance of density-dependent dispersal has been recognized in theory, few empirical studies have examined how immigration changes over a wide range of densities. In a replicated experiment using a novel approach allowing within-site comparison, we examined changes in immigration rate following the gradual removal of territorial damselfish from a limited area within a much larger patch of continuous habitat. In all sites, immigration occurred at intermediate densities but did not occur before the start of removals and only rarely as density approached zero. In the combined data and in 5 of 7 sites, the number of immigrants was a hump-shaped function of density. This is the first experimental evidence for hump-shaped, density-dependent immigration. This pattern may be more widespread than previously recognized because studies over more limited density ranges have identified positive density dependence at low densities and negative density dependence at high densities. Positive density dependence at low density can arise from limits to the number of potential immigrants and from behavioral preferences for settling near conspecifics. Negative density dependence at high density can arise from competition for resources, especially high quality territories. The potential for non-linear effects of local density on immigration needs to be recognized for robust predictions of conservation reserve function, harvest impacts, pest control, and the dynamics of fragmented populations. PMID:27271081

Consolidating the effects of waking and sleep on motor-sequence learning.

PubMed

Brawn, Timothy P; Fenn, Kimberly M; Nusbaum, Howard C; Margoliash, Daniel

2010-10-20

Sleep is widely believed to play a critical role in memory consolidation. Sleep-dependent consolidation has been studied extensively in humans using an explicit motor-sequence learning paradigm. In this task, performance has been reported to remain stable across wakefulness and improve significantly after sleep, making motor-sequence learning the definitive example of sleep-dependent enhancement. Recent work, however, has shown that enhancement disappears when the task is modified to reduce task-related inhibition that develops over a training session, thus questioning whether sleep actively consolidates motor learning. Here we use the same motor-sequence task to demonstrate sleep-dependent consolidation for motor-sequence learning and explain the discrepancies in results across studies. We show that when training begins in the morning, motor-sequence performance deteriorates across wakefulness and recovers after sleep, whereas performance remains stable across both sleep and subsequent waking with evening training. This pattern of results challenges an influential model of memory consolidation defined by a time-dependent stabilization phase and a sleep-dependent enhancement phase. Moreover, the present results support a new account of the behavioral effects of waking and sleep on explicit motor-sequence learning that is consistent across a wide range of tasks. These observations indicate that current theories of memory consolidation that have been formulated to explain sleep-dependent performance enhancements are insufficient to explain the range of behavioral changes associated with sleep.

Age dependency for coagulation parameters in paediatric populations. Results of a multicentre study aimed at defining the age-specific reference ranges.

PubMed

Toulon, Pierre; Berruyer, Micheline; Brionne-François, Marie; Grand, François; Lasne, Dominique; Telion, Caroline; Arcizet, Julien; Giacomello, Roberta; De Pooter, Neila

2016-07-04

Understanding of developmental haemostasis is critical to ensure optimal prevention, diagnosis, and treatment of haemorrhagic and thrombotic diseases in children. As coagulation test results are known to be dependent on the reagents/analysers used, it is recommended for each laboratory to define the age-dependent reference ranges by using its own technical condition. That study was carried out in seven centers to establish age-specific reference ranges using the same reagents and analyser. Plasma samples were obtained from 1437 paediatric patients from the following age groups: 15 days-4 weeks (n=36), 1-5 months (n=320), 6-12 months (n=176), 1-5 years (n=507), 6-10 years (n=132) and 11-17 years (n=262). Indication of coagulation testing was pre-operative screening for non-acute diseases in most cases. PT values were similar in the different age groups to those in adults, whereas longer aPTTs were demonstrated in the younger children. Plasma levels of all clotting factors, except for FV, were significantly decreased (p<0.0001) in the youngest children, adult values being usually reached before the end of the first year. The same applied to antithrombin, protein C/S, and plasminogen. In contrast, FVIII and VWF levels were elevated in the youngest children and returned to adult values within six months. The same applied to D-dimer levels, which were found elevated, particularly until six months of life, until puberty. These data suggest that most coagulation test results are highly dependent on age, mainly during the first year of life, and that age-specific reference ranges must be used to ensure proper evaluation of coagulation in children.

The Separate Physics and Dynamics Experiment (SPADE) framework for determining resolution awareness: A case study of microphysics

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

Gustafson, William I.; Ma, Po-Lun; Xiao, Heng

2013-08-29

The ability to use multi-resolution dynamical cores for weather and climate modeling is pushing the atmospheric community towards developing scale aware or, more specifically, resolution aware parameterizations that will function properly across a range of grid spacings. Determining the resolution dependence of specific model parameterizations is difficult due to strong resolution dependencies in many pieces of the model. This study presents the Separate Physics and Dynamics Experiment (SPADE) framework that can be used to isolate the resolution dependent behavior of specific parameterizations without conflating resolution dependencies from other portions of the model. To demonstrate the SPADE framework, the resolution dependencemore » of the Morrison microphysics from the Weather Research and Forecasting model and the Morrison-Gettelman microphysics from the Community Atmosphere Model are compared for grid spacings spanning the cloud modeling gray zone. It is shown that the Morrison scheme has stronger resolution dependence than Morrison-Gettelman, and that the ability of Morrison-Gettelman to use partial cloud fractions is not the primary reason for this difference. This study also discusses how to frame the issue of resolution dependence, the meaning of which has often been assumed, but not clearly expressed in the atmospheric modeling community. It is proposed that parameterization resolution dependence can be expressed in terms of "resolution dependence of the first type," RA1, which implies that the parameterization behavior converges towards observations with increasing resolution, or as "resolution dependence of the second type," RA2, which requires that the parameterization reproduces the same behavior across a range of grid spacings when compared at a given coarser resolution. RA2 behavior is considered the ideal, but brings with it serious implications due to limitations of parameterizations to accurately estimate reality with coarse grid spacing. The type of resolution awareness developers should target in their development depends upon the particular modeler’s application.« less

Absolute rate constant for the O plus NO chemiluminescence in the near infrared

NASA Technical Reports Server (NTRS)

Golde, M. F.; Roche, A. E.; Kaufman, F.

1973-01-01

Infrared chemiluminescence from the process O + NO (+M) NO2 + hv (+M) has been studied between 1.3 and 4.1 micrometer. The wavelength dependence of the continuum between 1.3 and 3.3 micrometer is in fair agreement with previous studies and the measured radiative rate constant at 1.51 micrometer establishes the NO-O glow in this spectral range as a secondary emission standard. Comparison with previous studies of the visible region of the glow implies that the overall radiative rate constant lies in the range (9.4 to 11.2) x 10 to the minus 17 power cu cm sec/1. In the region 3.3 to 4.1 micrometer, the previously observed broad band, peaking at 3.7 micrometer, shows a complex kinetic dependence on O and M.

Provenance studies by fission-track dating of zircon-etching and counting procedures

USGS Publications Warehouse

Naeser, N.D.; Zeitler, P.K.; Naeser, C.W.; Cerveny, P.F.

1987-01-01

In sedimentary rocks that have not been heated to high enough temperatures to anneal fission tracks in zircon (greater than ≈ 160°C), fission-track ages of individual detrital zircon grains provide valuable information about the source rocks eroded to form the sediments. The success of such studies depends, however, on the degree to which the ages determined from the detrital suite accurately portray the range of grain ages that are present in the suite. This in turn depends to a large extent on using counting and, in particular, etching procedures that permit proper sampling of grains with a wide range of age and uranium concentrations. Results are reported here of an experimental study of a ‘detrital’ zircon suite manufactured from several zircon populations of known age. This study suggests that multiple etches are required when a complete spectrum of ages in a zircon suite is desired.

Provenance studies by fission-track dating of zircon-etching and counting procedures

USGS Publications Warehouse

Naeser, Nancy D.; Zeitler, Peter K.; Naeser, Charles W.; Cerveny, Philip F.

1987-01-01

In sedimentary rocks that have not been heated to high enough temperatures to anneal fission tracks in zircon (greater than approximately equals 160 degree C), fission-track ages of individual detrital zircon grains provide valuable information about the source rocks eroded to form the sediments. The success of such studies depends, however, on the degree to which the ages determined from the detrital suite accurately portray the range of grain ages that are present in the suite. This in turn depends to a large extent on using counting and, in particular, etching procedures that permit proper sampling of grains with a wide range of age and uranium concentrations. Results are reported here of an experimental study of a 'detrital' zircon suite manufactured from several zircon populations of known age. This study suggests that multiple etches are required when a complete spectrum of ages in a zircon suite is desired.

Calix[4]pyrrole as a Chloride Anion Receptor: Solvent and Counter-Cation Effects

PubMed Central

Sessler, Jonathan L.; Gross, Dustin E.; Cho, Won-Seob; Lynch, Vincent M.; Schmidtchen, Franz P.; Bates, Gareth W.; Light, Mark E.; Gale, Philip A.

2008-01-01

The interaction of calixpyrrole with several chloride salts has been studied in the solid state by X-ray crystallography as well as in solution by isothermal titration calorimetry (ITC) and 1H NMR spectroscopic titrations. The titration results in dimethylsulfoxide, acetonitrile, nitromethane, 1,2-dichloroethane and dichloromethane, carried out using various chloride salts, specifically tetraethylammonium (TEA), tetrapropylammonium (TPA), tetrabutylammonium (TBA), tetraethylphosphonium (TEP), tetrabutylphosphonium (TBP), and tetraphenylphosphonium (TPhP) showed no dependence on method of measurement. The resulting affinity constants (Ka's), on the other hand, were found to be highly dependent on the choice of solvent with Ka's ranging from 102−105 being recorded in the test solvents used for this study. In dichloromethane a strong dependence on the counter-cation was also seen, with the Ka's for the interaction with chloride ranging from 102−104. In the case of TPA, TBA and TBP the ITC data could not be fit to a 1:1 binding profile. PMID:16967979

Characterization of commercial MOSFET detectors and their feasibility for in-vivo HDR brachytherapy.

PubMed

Phurailatpam, Reena; Upreti, Rituraj; Nojin Paul, Siji; Jamema, Swamidas V; Deshpande, Deepak D

2016-01-01

The present study was to investigate the use of MOSFET as an vivo dosimeter for the application of Ir-192 HDR brachytherapy treatments. MOSFET was characterized for dose linearity in the range of 50-1000 cGy, depth dose dependence from 2 to 7 cm, angular dependence. Signal fading was checked for two weeks. Dose linearity was found to be within 2% in the dose range (50-1000 cGy). The response varied within 8.07% for detector-source distance of 2-7 cm. The response of MOSFET with the epoxy side facing the source (0 degree) is the highest and the lowest response was observed at 90 and 270 degrees. Signal was stable during the study period. The detector showed high dose linearity and insignificant fading. But due to angular and depth dependence, care should be taken and corrections must be applied for clinical dosimetry. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Minority games with score-dependent and agent-dependent payoffs

NASA Astrophysics Data System (ADS)

Ren, F.; Zheng, B.; Qiu, T.; Trimper, S.

2006-10-01

Score-dependent and agent-dependent payoffs of the strategies are introduced into the standard minority game. The intrinsic periodicity is consequently removed, and the stylized facts arise, such as long-range volatility correlations and “fat tails” in the distribution of the returns. The agent dependence of the payoffs is essential in producing the long-range volatility correlations. The new payoffs lead to a better performance in the dynamic behavior nonlocal in time, and can coexist with the inactive strategy. We also observe that the standard deviation σ2/N is significantly reduced, thus the efficiency of the system is distinctly improved. Based on this observation, we give a qualitative explanation for the long-range volatility correlations.

Complete magnetic field dependence of SABRE-derived polarization.

PubMed

Kiryutin, Alexey S; Yurkovskaya, Alexandra V; Zimmermann, Herbert; Vieth, Hans-Martin; Ivanov, Konstantin L

2018-07-01

Signal amplification by reversible exchange (SABRE) is a promising hyperpolarization technique, which makes use of spin-order transfer from parahydrogen (the H 2 molecule in its singlet spin state) to a to-be-polarized substrate in a transient organometallic complex, termed the SABRE complex. In this work, we present an experimental method for measuring the magnetic field dependence of the SABRE effect over an ultrawide field range, namely, from 10 nT to 10 T. This approach gives a way to determine the complete magnetic field dependence of SABRE-derived polarization. Here, we focus on SABRE polarization of spin-1/2 hetero-nuclei, such as 13 C and 15 N and measure their polarization in the entire accessible field range; experimental studies are supported by calculations of polarization. Features of the field dependence of polarization can be attributed to level anticrossings in the spin system of the SABRE complex. Features at magnetic fields of the order of 100 nT-1 μT correspond to "strong coupling" of protons and hetero-nuclei, whereas features found in the mT field range stem from "strong coupling" of the proton system. Our approach gives a way to measuring and analyzing the complete SABRE field dependence, to probing NMR parameters of SABRE complexes and to optimizing the polarization value. Copyright © 2017 John Wiley & Sons, Ltd.

Dielectric behavior and AC conductivity of Cr doped α-Mn2O3

NASA Astrophysics Data System (ADS)

Chandra, Mohit; Yadav, Satish; Singh, K.

2018-05-01

The complex dielectric behavior of polycrystalline α-Mn2-xCrxO3 (x = 0.10) has been investigated isothermally at wide frequency range (4Hz-1 MHz) at different temperatures (300-390K). The dielectric spectroscopy results have been discussed in different formulism like dielectric constant, impedance and ac conductivity. The frequency dependent dielectric loss (tanδ) exhibit a clear relaxation behavior in the studied temperature range. The relaxation frequency increases with increasing temperature. These results are fitted using Arrhenius equation which suggest thermally activated process and the activation energy is 0.173±0.0024 eV. The normalized tanδ curves at different temperatures merge as a single master curve which indicate that the relaxation process follow the similar relaxation dynamics in the studied temperature range. Further, the dielectric relaxation follows non-Debye behavior. The impedance results inference that the grain boundary contribution dominate at lower frequency whereas grain contribution appeared at higher frequencies and exhibit strong temperature dependence. The ac conductivity data shows that the ac conductivity increases with increasing temperature which corroborate the semiconducting nature of the studied sample.

Prediction of operating parameters range for ammonia removal unit in coke making by-products

NASA Astrophysics Data System (ADS)

Tiwari, Hari Prakash; Kumar, Rajesh; Bhattacharjee, Arunabh; Lingam, Ravi Kumar; Roy, Abhijit; Tiwary, Shambhu

2018-02-01

Coke oven gas treatment plants are well equipped with distributed control systems (DCS) and therefore recording the vast amount of operational data efficiently. Analyzing the stored information manually from historians is practically impossible. In this study, data mining technique was examined for lowering the ammonia concentration in clean coke oven gas. Results confirm that concentration of ammonia in clean coke oven gas depends on the average PCDC temperature; gas scrubber temperatures stripped liquor flow, stripped liquor concentration and stripped liquor temperature. The optimum operating ranges of the above dependent parameters using data mining technique for lowering the concentration of ammonia is described in this paper.

Entanglement and quantum state geometry of a spin system with all-range Ising-type interaction

NASA Astrophysics Data System (ADS)

Kuzmak, A. R.

2018-04-01

The evolution of an N spin-1/2 system with all-range Ising-type interaction is considered. For this system we study the entanglement of one spin with the rest spins. It is shown that the entanglement depends on the number of spins and the initial state. Also, the geometry of the manifold, which contains entangled states, is obtained. For this case we find the dependence of entanglement on the scalar curvature of the manifold and examine it for different numbers of spins in the system. Finally we show that the transverse magnetic field leads to a change in the manifold topology.

Spectral long-range interaction of temporal incoherent solitons.

PubMed

Xu, Gang; Garnier, Josselin; Picozzi, Antonio

2014-02-01

We study the interaction of temporal incoherent solitons sustained by a highly noninstantaneous (Raman-like) nonlinear response. The incoherent solitons exhibit a nonmutual interaction, which can be either attractive or repulsive depending on their relative initial distance. The analysis reveals that incoherent solitons exhibit a long-range interaction in frequency space, which is in contrast with the expected spectral short-range interaction described by the usual approach based on the Raman-like spectral gain curve. Both phenomena of anomalous interaction and spectral long-range behavior of incoherent solitons are described in detail by a long-range Vlasov equation.

Home and Parenting Resources Available to Siblings Depending on Their Birth Intention Status

ERIC Educational Resources Information Center

Barber, Jennifer S.; East, Patricia L.

2009-01-01

This study examines the differential availability of family and parenting resources to children depending on their birth planning status. The National Longitudinal Survey of Youth data were analyzed, 3,134 mothers and their 5,890 children (M = 7.1 years, range = 1 month-14.8 years), of whom 63% were intended at conception, 27% were mistimed, and…

Ecological Correlates of Spanish Adolescents' Physical Activity during Physical Education Classes

ERIC Educational Resources Information Center

Molina-García, Javier; Queralt, Ana; Estevan, Isaac; Sallis, James F.

2016-01-01

The public health benefit of school physical education (PE) depends in large part on physical activity (PA) provided during class. According to the literature, PE has a valuable role in public health, and PA levels during PE classes depend on a wide range of factors. The main objective of this study, based on ecological models of behaviour, was to…

Temperature dependent GaAs MMIC radiation effects

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

Anderson, W.T.; Roussos, J.A.; Gerdes, J.

1993-12-01

The temperature dependence of pulsed neutron and flash x-ray radiation effects was studied in GaAs MMICs. Above room temperature the long term current transients are dominated by electron trapping in previously existing defects. At low temperature in the range 126 to 259 K neutron induced lattice damage appears to play an increasingly important role in producing long term current transients.

Clarifying the Relationship between Impulsive Delay Discounting and Nicotine Dependence

PubMed Central

Amlung, Michael; MacKillop, James

2014-01-01

Impulsive delayed reward discounting (DRD) has been linked to nicotine dependence, but with some inconsistency. This may be related to the considerable variability in the literature with regard to the DRD assessments used, particularly in the case of reward magnitudes assessed. In addition, previous studies have often not considered concurrent substance use when examining the relationship between DRD and nicotine dependence. The current study sought to further clarify the relationship between DRD and nicotine dependence by characterizing DRD across diverse reward magnitudes and incorporating other substance use. Daily smokers (N = 933) were assessed for DRD preferences across nine reward magnitudes (delayed reward range: $2.50–$850), comorbid substance use, and relevant demographic variables (age, education, income). A significant large effect size magnitude effect was found for DRD, reflecting steeper discounting for smaller delayed rewards, but significant correlations across magnitudes also suggested similar relative levels of discounting. Principal components analysis (PCA) was used to generate a single latent index of discounting across all magnitudes that accounted for 67% of the total variance. In both correlation and regression analyses, steeper composite DRD was significantly associated with nicotine dependence severity. This relationship remained statistically significant after incorporating demographic variables and alcohol and illicit drug use. These findings provide evidence of a specific link between impulsive DRD and nicotine dependence, and reveal that this association is robust across a broad range of monetary rewards. The study also demonstrates the utility of using PCA to generate latent indices of delay discounting across multiple magnitudes of delayed reward. PMID:24841186

Temperature-dependent μ-Raman investigation of struvite crystals.

PubMed

Prywer, Jolanta; Kasprowicz, D; Runka, T

2016-04-05

The effect of temperature on the vibrational properties of struvite crystals grown from silica gels was systematically studied by μ-Raman spectroscopy. The time-dependent Raman spectra recorded in the process of long time annealing of struvite crystal at 353 K do not indicate structural changes in the struvite crystal with the time of annealing. The temperature-dependent Raman spectra recorded in the range 298-423 K reveal a phase transition in struvite at about 368 K. Above this characteristic temperature, some of bands assigned to vibrations of the PO4 and NH4 tetrahedra and water molecules observed in the Raman spectra in low temperatures (orthorhombic phase) change their spectral parameters or disappear, which indicates a transition to a higher symmetry structure of struvite in the range of high temperatures. Copyright © 2016 Elsevier B.V. All rights reserved.

Interactions in hydrogen of relativistic neon to nickel projectiles: Total charge-changing cross sections

NASA Astrophysics Data System (ADS)

Chen, C.-X.; Albergo, S.; Caccia, Z.; Costa, S.; Crawford, H. J.; Cronqvist, M.; Engelage, J.; Ferrando, P.; Fonte, R.; Greiner, L.; Guzik, T. G.; Insolia, A.; Jones, F. C.; Knott, C. N.; Lindstrom, P. J.; Mitchell, J. W.; Potenza, R.; Romanski, J.; Russo, G. V.; Soutoul, A.; Testard, O.; Tull, C. E.; Tuvé, C.; Waddington, C. J.; Webber, W. R.; Wefel, J. P.; Zhang, X.

1994-06-01

A liquid hydrogen target was used to study the nuclear fragmentation of beams of relativistic heavy ions, 22Ne to 58Ni, over an energy range 400 to 900 MeV/nucleon. The experiments were carried out at the Lawrence Berkeley Laboratory Bevalac HISS facility, using the charge-velocity-rigidity method to identify the charged fragments. Here we describe the general concept of the experiment and present total charge-changing cross sections obtained from 17 separate runs. These new measured cross sections display an energy dependence which follows semiempirical model predictions. The mass dependence of the cross sections behaves as predicted by optical models, but within the experimental energy range, the optical model parameters display a clear energy dependence. The isospin of the projectile nuclei also appears to be an important factor in the interaction process.

Geostatistical Characterization of Cereal Leaf Beetle (Coleoptera: Chrysomelidae) Distributions in Wheat.

PubMed

Reay-Jones, Francis P F

2017-08-01

A 3-yr study was conducted in wheat, Triticum aestivum L., in South Carolina to characterize the spatial distribution of Oulema melanopus (L.) adults, eggs, and larvae using semivariograms, which provides a measure of spatial dependence among sampling data. Moran's I coefficients for peak densities of each life stage indicated significant positive autocorrelation for seven (two for eggs, one for larvae, and four for adults) of the 16 datasets. Aggregation was detected in 13 of these 16 datasets when analyzed by semivariogram modeling, with spherical, Gaussian, and exponential models best fitting for eight, four, and one dataset, respectively, and with models for two datasets having only one parameter (nugget) significantly different from zero. The nugget-to-sill ratios ranged from 0.043 to 0.774, and indicated strong spatial dependence in six models (three for adults, two for eggs, and one for larvae), moderate spatial dependence in six models (three for adults and six for eggs), and weak spatial dependence in one model (adults). Range values varied from 39.1 m to 234.1 m, with an average of 120.1 ± 14.0 m. Average range values were 104.9, 135.2, and 161.2 m for adults, eggs, and larvae, respectively. Because the majority of semivariogram models in our study indicated aggregated distributions, spatial sampling will provide more information than nonspatial random sampling. Developing our understanding of spatial dependence of crop pests is needed to optimize sampling plans and can provide a basis for exploring site-specific management tactics. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Heritability of MMPI-2 scales in the UCSF Family Alcoholism Study

PubMed Central

Gizer, Ian R.; Seaton-Smith, Kimberley L.; Ehlers, Cindy L.; Vietan, Cassandra; Wilhelmsen, Kirk C.

2009-01-01

The present study evaluated the heritability of personality traits and psychopathology symptoms assessed by the Minnesota Multiphasic Personality Interview 2nd edition (MMPI-2) in a family-based sample selected for alcohol dependence. Participants included 950 probands and 1204 first-degree relatives recruited for the UCSF Family Alcoholism Study. Heritability estimates (h2) for MMPI-2 scales ranged from .25–.49. When alcohol dependence was used as a covariate, heritability estimates remained significant but generally declined. However, when the MMPI-2 scales were used as covariates to estimate the heritability of alcohol dependence, scales measuring antisocial behavior (ASP), depressive symptoms (DEP), and addictive behavior (MAC-R) led to moderate increases in the heritability of alcohol dependence. This suggests that the ASP, DEP, and MAC-R scales may explain some of the non-genetic variance in the alcohol dependence diagnosis in this population when utilized as covariates, and thus may serve to produce a more homogeneous and heritable alcohol dependence phenotype. PMID:20390702

Characteristics of an OSLD in the diagnostic energy range.

PubMed

Al-Senan, Rani M; Hatab, Mustapha R

2011-07-01

Optically stimulated luminescence (OSL) dosimetry has been recently introduced in radiation therapy as a potential alternative to the thermoluminescent dosimeter (TLD) system. The aim of this study was to investigate the feasibility of using OSL point dosimeters in the energy range used in diagnostic imaging. NanoDot OSL dosimeters (OSLDs) were used in this study, which started with testing the homogeneity of a new packet of nanoDots. Reproducibility and the effect of optical treatment (bleaching) were then examined, followed by an investigation of the effect of accumulated dose on the OSLD indicated doses. OSLD linearity, angular dependence, and energy dependence were also studied. Furthermore, comparison with LiF:Mg,Ti TLD chips using standard CT dose phantoms at 80 and 120 kVp settings was performed. Batch homogeneity showed a coefficient of variation of <5%. Single-irradiation measurements with bleaching after each OSL readout was found to be associated with a 3.3% reproducibility (one standard deviation measured with a 8 mGy test dose), and no systematic change in OSLDs sensitivity could be noted from measurement to measurement. In contrast, the multiple-irradiation readout without bleaching in between measurements was found to be associated with an uncertainty (using a 6 mGy test dose) that systematically increased with accumulated dose, reaching 42% at 82 mGy. Good linearity was shown by nanoDots under general x-ray, CT, and mammography units with an R2 > 0.99. The angular dependence test showed a drop of approximately 70% in the OSLD response at 90 degrees in mammography (25 kVp). With the general radiography unit, the maximum drop was 40% at 80 kVp and 20% at 120 kVp, and it was only 10% with CT at both 80 and 120 kVp. The energy dependence study showed a range of ion chamber-to-OSLDs ratios between 0.81 and 1.56, at the energies investigated (29-62 keV). A paired t-test for comparing the OSLDs and TLDs showed no significant variation (p > 0.1). OSLDs exhibited good batch homogeneity (<5%) and reproducibility (3.3%), as well as a linear response. In addition, they showed no statistically significant difference with TLDs in CT measurements (p > 0.1). However, high uncertainty (42%) in the dose estimate was found as a result of relatively high accumulated dose. Furthermore, nanoDots showed high angular dependence (up to 70%) in low kVp techniques. Energy dependence of about 60% was found, and correction factors were suggested for the range of energies investigated. Therefore, if angular and energy dependences are taken into consideration and the uncertainty associated with accumulated dose is avoided, OSLDs (nanoDots) can be suitable for use as point dosimeters in diagnostic settings.

Dependability analysis of parallel systems using a simulation-based approach. M.S. Thesis

NASA Technical Reports Server (NTRS)

Sawyer, Darren Charles

1994-01-01

The analysis of dependability in large, complex, parallel systems executing real applications or workloads is examined in this thesis. To effectively demonstrate the wide range of dependability problems that can be analyzed through simulation, the analysis of three case studies is presented. For each case, the organization of the simulation model used is outlined, and the results from simulated fault injection experiments are explained, showing the usefulness of this method in dependability modeling of large parallel systems. The simulation models are constructed using DEPEND and C++. Where possible, methods to increase dependability are derived from the experimental results. Another interesting facet of all three cases is the presence of some kind of workload of application executing in the simulation while faults are injected. This provides a completely new dimension to this type of study, not possible to model accurately with analytical approaches.

Measurements of lateral penumbra for uniform scanning proton beams under various beam delivery conditions and comparison to the XiO treatment planning system

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

Rana, Suresh; Zeidan, Omar; Ramirez, Eric

2013-09-15

Purpose: The main purposes of this study were to (1) investigate the dependency of lateral penumbra (80%–20% distance) of uniform scanning proton beams on various factors such as air gap, proton range, modulation width, compensator thickness, and depth, and (2) compare the lateral penumbra calculated by a treatment planning system (TPS) with measurements.Methods: First, lateral penumbra was measured using solid–water phantom and radiographic films for (a) air gap, ranged from 0 to 35 cm, (b) proton range, ranged from 8 to 30 cm, (c) modulation, ranged from 2 to 10 cm, (d) compensator thickness, ranged from 0 to 20 cm,more » and (e) depth, ranged from 7 to 15 cm. Second, dose calculations were computed in a virtual water phantom using the XiO TPS with pencil beam algorithm for identical beam conditions and geometrical configurations that were used for the measurements. The calculated lateral penumbra was then compared with the measured one for both the horizontal and vertical scanning magnets of our uniform scanning proton beam delivery system.Results: The results in the current study showed that the lateral penumbra of horizontal scanning magnet was larger (up to 1.4 mm for measurement and up to 1.0 mm for TPS) compared to that of vertical scanning magnet. Both the TPS and measurements showed an almost linear increase in lateral penumbra with increasing air gap as it produced the greatest effect on lateral penumbra. Lateral penumbra was dependent on the depth and proton range. Specifically, the width of lateral penumbra was found to be always lower at shallower depth than at deeper depth within the spread out Bragg peak (SOBP) region. The lateral penumbra results were less sensitive to the variation in the thickness of compensator, whereas lateral penumbra was independent of modulation. Overall, the comparison between the results of TPS with that of measurements indicates a good agreement for lateral penumbra, with TPS predicting higher values compared to measurements.Conclusions: Lateral penumbra of uniform scanning proton beams depends on air gap, proton range, compensator thickness, and depth, whereas lateral penumbra is not dependent on modulation. The XiO TPS typically overpredicted lateral penumbra compared to measurements, within 1 mm for most cases, but the difference could be up to 2.5 mm at a deep depth and large air gap.« less

Determination of Age-Dependent Reference Ranges for Coagulation Tests Performed Using Destiny Plus.

PubMed

Arslan, Fatma Demet; Serdar, Muhittin; Merve Ari, Elif; Onur Oztan, Mustafa; Hikmet Kozcu, Sureyya; Tarhan, Huseyin; Cakmak, Ozgur; Zeytinli, Merve; Yasar Ellidag, Hamit

2016-06-01

In order to apply the right treatment for hemostatic disorders in pediatric patients, laboratory data should be interpreted with age-appropriate reference ranges. The purpose of this study was to determining age-dependent reference range values for prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen tests, and D-dimer tests. A total of 320 volunteers were included in the study with the following ages: 1 month - 1 year (n = 52), 2 - 5 years (n = 50), 6 - 10 years (n = 48), 11 - 17 years (n = 38), and 18 - 65 years (n = 132). Each volunteer completed a survey to exclude hemostatic system disorder. Using a nonparametric method, the lower and upper limits, including 95% distribution and 90% confidence intervals, were calculated. No statistically significant differences were found between PT and aPTT values in the groups consisting of children. Thus, the reference ranges were separated into child and adult age groups. PT and aPTT values were significantly higher in the children than in the adults. Fibrinogen values in the 6 - 10 age group and the adult age group were significantly higher than in the other groups. D-dimer levels were significantly lower in those aged 2 - 17; thus, a separate reference range was established. These results support other findings related to developmental hemostasis, confirming that adult and pediatric age groups should be evaluated using different reference ranges.

Model function to calculate the refractive index of native hemoglobin in the wavelength range of 250-1100 nm dependent on concentration.

PubMed

Friebel, Moritz; Meinke, Martina

2006-04-20

The real part of the complex refractive index of oxygenated native hemoglobin solutions dependent on concentration was determined in the wavelength range 250 to 1100 nm by Fresnel reflectance measurements. The hemoglobin solution was produced by physical hemolysis of human erythrocytes followed by ultracentrifugation and filtration. A model function is presented for calculating the refractive index of hemoglobin solutions depending on concentration in the wavelength range 250 to 1100 nm.

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

Battum, LJ van; Heukelom, S

Purpose This study investigates the origin of lateral optical density (OD) variation for Gafchromic film (EBT and EBT2) scanned in transmission mode with Epson flatbed scanners (1680 Expression Pro and 10000XL). Effects investigated are: cross talk, optical path length and polarization. Methods Cross talk has been examined with triangular shaped light-transmission sheets with OD ranging from 0 to opaque. Optical path length has been studied with absorptive and reflective OD-filters (OD range 0.2 to 2.0). Dependency on light-polarization on the scanner read out has been investigated using linear polarizer sheets. All experiments have been performed at centre scanner position (normmore » point) and at several lateral scan positions, without and with (un)irradiated EBT-film. Dose values used ranged between 0.2 to 9 Gy, yielding an OD-range between 0.25 to 1.1. Results The lateral OD variation is dose dependent and increases up to 14% at most lateral position for dose up to 9 Gy. Cross talk effect contributes to 0.5% in clinical used OD ranges but equals 2% for extreme high dose gradients. Film induced optical path length will effect the lateral OD variation up to 3% at most lateral points. Light polarization is inherent present in these scanners due to multiple reflection on mirrors. In addition film induced polarization is the most important effect generating the observed lateral OD variation. Both Gafchromic film base and sensitive layer have polarizing capabilities; for the sensitive layer its influence is dose dependent. Conclusions Lateral OD variation origins from optical physics (i.e. polarization and reflection) related to scanner and film construction. Cross talk can be ignored in film dosimetry for clinical used dose values and gradients. Therefore it is recommended to determine the lateral OD variation per film type and scanner.« less

Anabolic hormone profiles in elite military men: Robust associations with age, stress, and fatigue.

PubMed

Taylor, Marcus K; Padilla, Genieleah A; Hernández, Lisa M

2017-08-01

We recently established stable daily profiles of the anabolic hormones dehydroepiandrosterone (DHEA) and testosterone in 57 elite military men. In this follow-on study, we explored associations of salivary anabolic hormone profiles with demographic (i.e., age, body mass index [BMI]) and biobehavioral health indices (i.e., blood pressure, sleep, perceived stress, fatigue) via correlational models. Next, nuanced patterns were constructed using quartile splits followed by one-way analysis of variance and post hoc subgroup comparisons. Both DHEA (r range: -0.33 to -0.49) and testosterone (r range: -0.19 to -0.41) were inversely associated with age. Quartile comparisons revealed that age-related declines in DHEA were linear, curvilinear, or sigmoidal, depending on the summary parameter of interest. Anabolic hormone profiles did not associate with BMI, blood pressure, or sleep efficiency. Robust linear associations were observed between testosterone and perceived stress (r range: -0.29 to -0.36); concentration-dependent patterns were less discernible. Lower DHEA (r range: -0.22 to -0.30) and testosterone (r range: -0.22 to -0.36) concentrations associated with higher fatigue. Subsequent quartile comparisons suggested a concentration-dependent threshold with respect to evening testosterone. Specifically, those individuals within the lowest quartile (≤68.4pg/mL) endorsed the highest fatigue of the four groups (p=0.01), while the remaining three groups did not differ from each other. This study not only showed that anabolic hormone profiles have distinctive age trajectories, but are also valuable predictors of stress and fatigue in elite military men. This highlights the importance of routine monitoring of anabolic hormone profiles to sustain and optimize health and readiness in chronically stressed populations. Published by Elsevier Inc.

Temperature dependence of the elastocaloric effect in natural rubber

NASA Astrophysics Data System (ADS)

Xie, Zhongjian; Sebald, Gael; Guyomar, Daniel

2017-07-01

The temperature dependence of the elastocaloric (eC) effect in natural rubber (NR) has been studied. This material exhibits a large eC effect over a broad temperature range from 0 °C to 49 °C. The maximum adiabatic temperature change (ΔT) occurred at 10 °C and the behavior could be predicted by the temperature dependence of the strain-induced crystallization (SIC) and the temperature-induced crystallization (TIC). The eC performance of NR was then compared with that of shape memory alloys (SMAs). This study contributes to the SIC research of NR and also broadens the application of elastomers.

Temperature dependence of plastic scintillators

NASA Astrophysics Data System (ADS)

Peralta, L.

2018-03-01

Plastic scintillator detectors have been studied as dosimeters, since they provide a cost-effective alternative to conventional ionization chambers. Several articles have reported undesired response dependencies on beam energy and temperature, which provides the motivation to determine appropriate correction factors. In this work, we studied the light yield temperature dependency of four plastic scintillators, BCF-10, BCF-60, BC-404, RP-200A and two clear fibers, BCF-98 and SK-80. Measurements were made using a 50 kVp X-ray beam to produce the scintillation and/or radioluminescence signal. The 0 to 40 °C temperature range was scanned for each scintillator, and temperature coefficients were obtained.

Localization and tracking of moving objects in two-dimensional space by echolocation.

PubMed

Matsuo, Ikuo

2013-02-01

Bats use frequency-modulated echolocation to identify and capture moving objects in real three-dimensional space. Experimental evidence indicates that bats are capable of locating static objects with a range accuracy of less than 1 μs. A previously introduced model estimates ranges of multiple, static objects using linear frequency modulation (LFM) sound and Gaussian chirplets with a carrier frequency compatible with bat emission sweep rates. The delay time for a single object was estimated with an accuracy of about 1.3 μs by measuring the echo at a low signal-to-noise ratio (SNR). The range accuracy was dependent not only on the SNR but also the Doppler shift, which was dependent on the movements. However, it was unclear whether this model could estimate the moving object range at each timepoint. In this study, echoes were measured from the rotating pole at two receiving points by intermittently emitting LFM sounds. The model was shown to localize moving objects in two-dimensional space by accurately estimating the object's range at each timepoint.

Postfledging nest dependence period for bald eagles in Florida

USGS Publications Warehouse

Wood, P.B.; Collopy, Michael W.; Sekerak, C.M.

1998-01-01

We studied the postfledging dependency period in bald eagles (Haliaeetus leucocephalus), a little studied but important period in the life cycle of avian species. Bald eagles in Florida had a postfledging dependency period of 4-11 weeks (15-22 weeks old). The length of the dependency period did not vary by year of study, sex, number of fledgings, timing of fledging, or hatch order (P > 0.05). Mean distance fledglings ranged from the nest increased with age, but they were observed in the nest or nest tree throughout the postfledging dependency period. Distance from the nest did not vary by sex, number of fledglings, or timing of fledging (P > 0.05). Over 80% of the fledgling observations were within 229 m of the nest. The boundary of the primary protection zone specified in the bald eagle habitat management guidelines for the southeastern United States is 229 m. Restrictions on human disturbance around nest sites should remain in place during the postfledging dependency period because of the close association of fledglings with the nest site. Restrictions also should be flexible because of the varying length of the dependency period.

Pulsed laser photolysis kinetics study of the O(3P) + ClO reaction

NASA Technical Reports Server (NTRS)

Nicovich, J. M.; Wine, P. H.; Ravishankara, A. R.

1988-01-01

A pulsed laser photolysis technique was used to investigate the kinetics of the important stratospheric reaction O + ClO yields Cl + O2 in buffer gas over the temperature and pressure ranges of 231-367 K and 25-500 torr. The results indicate a lack of pressure dependence at 298 K over the 25-500 torr range.

Children's Levels of Contingent Self-Esteem and Social and Emotional Outcomes

ERIC Educational Resources Information Center

Moore, Jonathan S. B.; Smith, Marjorie

2018-01-01

Contingent self-esteem (CSE) describes the degree to which self-esteem is dependent on meeting day-to-day appraisals from oneself and others. This will vary between individuals, ranging from lower to higher CSE. A lower CSE is related to a range of adaptive social and emotional outcomes in adolescents and young adults. This study explores…

[Performance dependence of organic light-emitting devices on the thickness of Alq3 emitting layer].

PubMed

Lian, Jia-rong; Liao, Qiao-sheng; Yang, Rui-bo; Zheng, Wei; Zeng, Peng-ju

2010-10-01

The dependence of opto-electronical characteristics in organic light-emitting devices on the thickness of Alq3 emitter layer was studied, where MoO3, NPB, and Alq3 were used as hole injector, hole transporter, and emitter/electron transporter, respectively. By increasing the thickness of Alq3 layer from 20 to 100 nm, the device current decreased gradually, and the EL spectra of devices performed a little red shift with an obvious broadening in long wavelength range but a little decrease in intensity of short wavelength range. The authors simulated the EL spectra using the photoluminescence (PL) spectra of Alq3 as Alq3 intrinsic emission, which coincided with the experimental EL spectra well. The simulated results suggested that the effect of interference takes the major role in broadening the long wavelength range of EL spectra, and the distribution of emission zone largely affects the profile of EL spectra in short wavelength range.

Elastic parabolic equation solutions for oceanic T-wave generation and propagation from deep seismic sources.

PubMed

Frank, Scott D; Collis, Jon M; Odom, Robert I

2015-06-01

Oceanic T-waves are earthquake signals that originate when elastic waves interact with the fluid-elastic interface at the ocean bottom and are converted to acoustic waves in the ocean. These waves propagate long distances in the Sound Fixing and Ranging (SOFAR) channel and tend to be the largest observed arrivals from seismic events. Thus, an understanding of their generation is important for event detection, localization, and source-type discrimination. Recently benchmarked seismic self-starting fields are used to generate elastic parabolic equation solutions that demonstrate generation and propagation of oceanic T-waves in range-dependent underwater acoustic environments. Both downward sloping and abyssal ocean range-dependent environments are considered, and results demonstrate conversion of elastic waves into water-borne oceanic T-waves. Examples demonstrating long-range broadband T-wave propagation in range-dependent environments are shown. These results confirm that elastic parabolic equation solutions are valuable for characterization of the relationships between T-wave propagation and variations in range-dependent bathymetry or elastic material parameters, as well as for modeling T-wave receptions at hydrophone arrays or coastal receiving stations.

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

Volotskova, O; Xu, A; Jozsef, G

Purpose: To investigate the response and dose rate dependence of a scintillation detector over a wide energy range. Methods: The energy dependence of W1 scintillation detector was tested with: 1) 50–225 keV beams generated by an animal irradiator, 2) a Leksell Gamma Knife Perfexion Co-60 source, 3) 6MV, 6FFF, 10FFF and 15MV photon beams, and 4) 6–20MeV electron beams from a linac. Calibrated linac beams were used to deliver 100 cGy to the detector at dmax in water under reference conditions. The gamma-knife measurement was performed in solid water (100 cGy with 16mm collimator). The low energy beams were calibratedmore » with an ion chamber in air (TG-61), and the scintillation detector was placed at the same location as the ionization chamber during calibration. For the linac photon and electron beams, dose rate dependence was tested for 100–2400 and 100–800 MU/min. Results: The scintillation detector demonstrated strong energy dependence in the range of 50–225keV. The measured values were lower than the delivered dose and increased as the energy increased. Therapeutic photon beams showed energy independence with variations less than 1%. Therapeutic electron beams displayed the same sensitivity of ∼2–3% at their corresponding dmax depths. The change in dose-rate of photon and electron beams within the therapeutic energy range did not affect detector output (<0.5%). Measurements acquired with the gamma knife showed that the output data agreed with the delivered dose up to 3%. Conclusion: W1 scintillation detector output has a strong energy dependence in the diagnostic and orthovoltage energy range. Therapeutic photon beams exhibited energy independence with no observable dose-rate dependence. This study may aid in the implementation of a scintillation detector in QA programs by providing energy calibration factors.« less

Effect of Electrode Loss on the Dynamic Range of Linearized Directional Coupler Modulators

DTIC Science & Technology

2006-02-01

Coupler Modulators George A. Brost , Richard Michalak, Paul Payson, and Kevin Magde Abstract—Numerical simulations were used to study the effect of...RANGE OF LINEARIZED DIRECTIONAL COUPLER MODULATORS In-House N/A 62204F LINKI SN 01 George A. Brost , Richard Michalak, Paul Payson and Kevin Magde AFRL...Fazio Nash BROST et al.: EFFECT OF ELECTRODE LOSS ON THE DYNAMIC RANGE OF LINEARIZED DCMs 515 Fig. 1. Frequency dependence of SFDR for the 1 2 DCM (s

Temperature and composition dependence of short-range order and entropy, and statistics of bond length: the semiconductor alloy (GaN)(1-x)(ZnO)(x).

PubMed

Liu, Jian; Pedroza, Luana S; Misch, Carissa; Fernández-Serra, Maria V; Allen, Philip B

2014-07-09

We present total energy and force calculations for the (GaN)1-x(ZnO)x alloy. Site-occupancy configurations are generated from Monte Carlo (MC) simulations, on the basis of a cluster expansion model proposed in a previous study. Local atomic coordinate relaxations of surprisingly large magnitude are found via density-functional calculations using a 432-atom periodic supercell, for three representative configurations at x = 0.5. These are used to generate bond-length distributions. The configurationally averaged composition- and temperature-dependent short-range order (SRO) parameters of the alloys are discussed. The entropy is approximated in terms of pair distribution statistics and thus related to SRO parameters. This approximate entropy is compared with accurate numerical values from MC simulations. An empirical model for the dependence of the bond length on the local chemical environments is proposed.

Conductance Change Induced by the Rashba Effect in the LaAlO3/SrTiO3 Interface.

PubMed

Kim, Taeyueb; Kim, Shin-Ik; Baek, Seung-Hyub; Hong, Jinki; Koo, Hyun Cheol

2015-11-01

The LaAlO3/SrTiO3 (LAO/STO) heterostructure has an inherent space inversion asymmetry causing an internal electric field near the interface. The Rashba spin-orbit coupling arising from this structural characteristic has a considerable influence on spin transport. With application of an external magnetic field, we observed conductance change in the LAO/STO interface which depends on the sign and magnitude of the field. Our systematic study revealed that these results come from spin dependent transport, by which we obtained quantitative strength of the Rashba effect. The Rashba strength in this system depends on the temperature: it varies from 2.6 x 10(-12) eVm to negligible value in the temperature range of 1.8 K-12 K. This method for detecting Rashba effect covers a wider temperature range in comparison with those obtained from Shubnikov-de Haas oscillation or weak antilocalization measurements.

Dependence of hydrogen arcjet operation on electrode geometry

NASA Technical Reports Server (NTRS)

Pencil, Eric J.; Sankovic, John M.; Sarmiento, Charles J.; Hamley, John A.

1992-01-01

The dependence of 2 kW hydrogen arcjet performance on cathode to anode electrode spacing was evaluated at specific impulses of 900 and 1000 s. Less than 2 absolute percent change in efficiency was measured for the spacings tested which did not repeat the 14 absolute percent variation reported in earlier work with similar electrode designs. A different nozzle configuration was used to quantify the variation in hydrogen arcjet performance over an extended range of electrode spacing. Electrode gap variation resulted in less than 3 absolute percent change in efficiency. These null results suggested that electrode spacing is decoupled from hydrogen arcjet performance considerations over the ranges tested. Initial studies were conducted on hydrogen arcjet ignition. The dependence of breakdown voltage on mass flow rate and hydrogen arcjet ignition on rates of pulse repetition and pulse voltage rise were also included for comparison with previous results obtained using simulated hydrazine.

Ice-based altitude distribution of natural radiation annual exposure rate in the Antarctica zone over the latitude range 69 degrees S-77 degrees S using a pair-filter thermoluminescence method.

PubMed

Nakajima, T; Kamiyama, T; Fujii, Y; Motoyama, H; Esumi, S

1995-12-01

Both ice-based altitude distributions of natural ionizing radiation exposure and the quasi-effective energy of natural radiation over Antartica over the latitude range 69 degrees S - 77 degrees S during approx. 500 days were measured using thermoluminescent dosimeters. The results shows that dependence on altitude above sea level of the exposure rate increases by almost three-fold with each increase of 2000 m of altitude, thus deviating from the general rule stating that the exposure rate should double with each 2000 m. Although the exposure rate shows a dependence on altitude, altitude dependence of the quasi-effective energy of natural radiation over Antartica is not observed. In the present study it is observed that natural radiation occurring over the ice base of Antartica consists mainly of cosmic rays.

Motion-plane dependency of the range of dart throw motion and the effects of tendon action due to finger extrinsic muscles during the motion.

PubMed

Mitsukane, Masahiro; Sekiya, Noboru; Kamono, Arinori; Nakabo, Tohru

2018-03-01

[Purpose] To clarify the motion-plane dependency of the range of dart throw motion and the effects of tendon action due to long finger flexors and extensors during the motion. [Subjects and Methods] Forty healthy subjects attended the experiment, and the active range of wrist motion in seven motion planes was measured with an originally designed apparatus. [Results] The reliability of the measurement was acceptable. The range of dart throw motion depended on the motion planes, with a maximum at around the motion plane of 45° from the sagittal plane (45° of pronation). The tendon action of long finger muscles was shown in dart throw motion except in 45° of pronation. [Conclusion] Motion-plane dependency of the range of dart throw motion exists in healthy subjects. The absence of tendon action due to finger extrinsic muscles in dart throw motion at 45° might be one of the causes of the advantage of dart throw motion.

Angle-resolved photoelectron spectroscopy of formaldehyde and methanol

NASA Astrophysics Data System (ADS)

Keller, P. R.; Taylor, J. W.; Grimm, F. A.; Carlson, Thomas A.

1984-10-01

Angle-resolved photoelectron spectroscopy was employed to obtain the angular distribution parameter, β, for the valence orbitals (IP < 21.1 eV) of formaldehyde and methanol over the 10-30 eV photon energy range using dispersed polarized synchrotron radiation as the excitation source. It was found that the energy dependence of β in the photoelectron energy range between 2 and 10 eV can be related to the molecular-orbital type from which ionization occurs. This generalized energy behavior is discussed with regard to earlier energy-dependence studies on molecules of different orbital character. Evidence is presented for the presence of resonance photoionization phenomena in formaldehyde in agreement with theoretical cross-section calculations.

Nonlocality and Short-Range Wetting Phenomena

NASA Astrophysics Data System (ADS)

Parry, A. O.; Romero-Enrique, J. M.; Lazarides, A.

2004-08-01

We propose a nonlocal interfacial model for 3D short-range wetting at planar and nonplanar walls. The model is characterized by a binding-potential functional depending only on the bulk Ornstein-Zernike correlation function, which arises from different classes of tubelike fluctuations that connect the interface and the substrate. The theory provides a physical explanation for the origin of the effective position-dependent stiffness and binding potential in approximate local theories and also obeys the necessary classical wedge covariance relationship between wetting and wedge filling. Renormalization group and computer simulation studies reveal the strong nonperturbative influence of nonlocality at critical wetting, throwing light on long-standing theoretical problems regarding the order of the phase transition.

Nonlocality and short-range wetting phenomena.

PubMed

Parry, A O; Romero-Enrique, J M; Lazarides, A

2004-08-20

We propose a nonlocal interfacial model for 3D short-range wetting at planar and nonplanar walls. The model is characterized by a binding-potential functional depending only on the bulk Ornstein-Zernike correlation function, which arises from different classes of tubelike fluctuations that connect the interface and the substrate. The theory provides a physical explanation for the origin of the effective position-dependent stiffness and binding potential in approximate local theories and also obeys the necessary classical wedge covariance relationship between wetting and wedge filling. Renormalization group and computer simulation studies reveal the strong nonperturbative influence of nonlocality at critical wetting, throwing light on long-standing theoretical problems regarding the order of the phase transition.

Antibody-dependent enhancement of severe dengue disease in humans*

PubMed Central

Katzelnick, Leah C.; Gresh, Lionel; Halloran, M. Elizabeth; Mercado, Juan Carlos; Kuan, Guillermina; Gordon, Aubree; Balmaseda, Angel; Harris, Eva

2018-01-01

For dengue viruses (DENV1-4), a specific range of antibody titer has been shown to enhance viral replication in vitro and severe disease in animal models. Although suspected, such antibody-dependent enhancement (ADE) of severe disease has not been shown to occur in humans. Using multiple statistical approaches to study a long-term pediatric cohort in Nicaragua, we show that risk of severe dengue disease is highest within a narrow range of pre-existing anti-DENV antibody titers. By contrast, we observe protection from all symptomatic dengue disease at high antibody titers. Thus, immune correlates of severe dengue must be evaluated separately from correlates of protection against symptomatic disease. These results have implications for studies of dengue pathogenesis and for vaccine development, because enhancement, not just lack of protection, is of concern. PMID:29097492

Density-dependent home-range size revealed by spatially explicit capture–recapture

USGS Publications Warehouse

Efford, M.G.; Dawson, Deanna K.; Jhala, Y.V.; Qureshi, Q.

2016-01-01

The size of animal home ranges often varies inversely with population density among populations of a species. This fact has implications for population monitoring using spatially explicit capture–recapture (SECR) models, in which both the scale of home-range movements σ and population density D usually appear as parameters, and both may vary among populations. It will often be appropriate to model a structural relationship between population-specific values of these parameters, rather than to assume independence. We suggest re-parameterizing the SECR model using kp = σp √Dp, where kp relates to the degree of overlap between home ranges and the subscript p distinguishes populations. We observe that kp is often nearly constant for populations spanning a range of densities. This justifies fitting a model in which the separate kp are replaced by the single parameter k and σp is a density-dependent derived parameter. Continuous density-dependent spatial variation in σ may also be modelled, using a scaled non-Euclidean distance between detectors and the locations of animals. We illustrate these methods with data from automatic photography of tigers (Panthera tigris) across India, in which the variation is among populations, from mist-netting of ovenbirds (Seiurus aurocapilla) in Maryland, USA, in which the variation is within a single population over time, and from live-trapping of brushtail possums (Trichosurus vulpecula) in New Zealand, modelling spatial variation within one population. Possible applications and limitations of the methods are discussed. A model in which kp is constant, while density varies, provides a parsimonious null model for SECR. The parameter k of the null model is a concise summary of the empirical relationship between home-range size and density that is useful in comparative studies. We expect deviations from this model, particularly the dependence of kp on covariates, to be biologically interesting.

Frequency and temperature dependent dielectric properties of TiO2-V2O5 nanocomposites

NASA Astrophysics Data System (ADS)

Ray, Apurba; Roy, Atanu; De, Sayan; Chatterjee, Souvik; Das, Sachindranath

2018-03-01

In this manuscript, we have reported the crystal structure, dielectric response, and transport phenomenon of TiO2-V2O5 nanocomposites. The nanocomposites were synthesized using a sol-gel technique having different molar ratios of Ti:V (10:10, 10:15, and 10:20). The phase composition and the morphology have been studied using X-ray diffraction and field emission scanning electron microscope, respectively. The impedance spectroscopy studies of the three samples over a wide range of temperature (50 K-300 K) have been extensively described using the internal barrier layer capacitor model. It is based on the contribution of domain and domain boundary, relaxations of the materials, which are the main crucial factors for the enhancement of the dielectric response. The frequency dependent ac conductivity of the ceramics strongly obeys the well-known Jonscher's power law, and it has been clearly explained using the theory of jump relaxation model. The temperature dependent bulk conductivity is fairly recognized to the variable-range hopping of localized polarons. The co-existence of mixed valence state of Ti ions (Ti3+ and Ti4+) in the sample significantly contributes to the change of dielectric property. The overall study of dielectric response explains that the dielectric constant and the dielectric loss are strongly dependent on temperature and frequency and decrease with an increase of frequency as well as temperature.

A study of isotropic-nematic transition of quadrupolar Gay-Berne fluid using density-functional theory approach

NASA Astrophysics Data System (ADS)

Singh, Ram Chandra; Ram, Jokhan

2011-11-01

The effects of quadrupole moments on the isotropic-nematic (IN) phase transitions are studied using the density-functional theory (DFT) for a Gay-Berne (GB) fluid for a range of length-to-breadth parameters ? in the reduced temperature range ? . The pair-correlation functions of the isotropic phase, which enter into the DFT as input parameters are found by solving the Percus-Yevick integral equation theory. The method used involves an expansion of angle-dependent functions appearing in the integral equations in terms of spherical harmonics and the harmonic coefficients are obtained by an iterative algorithm. All the terms of harmonic coefficients which involve l indices up to less than or equal to 6 are considered. The numerical accuracy of the results depends on the number of spherical harmonic coefficients considered for each orientation-dependent function. As the length-to-breadth ratio of quadrupolar GB molecules is increased, the IN transition is seen to move to lower density (and pressure) at a given temperature. It has been observed that the DFT is good to study the IN transitions in such fluids. The theoretical results have also been compared with the computer simulation results wherever they are available.

The Rate of Beneficial Mutations Surfing on the Wave of a Range Expansion

PubMed Central

Lehe, Rémi; Hallatschek, Oskar; Peliti, Luca

2012-01-01

Many theoretical and experimental studies suggest that range expansions can have severe consequences for the gene pool of the expanding population. Due to strongly enhanced genetic drift at the advancing frontier, neutral and weakly deleterious mutations can reach large frequencies in the newly colonized regions, as if they were surfing the front of the range expansion. These findings raise the question of how frequently beneficial mutations successfully surf at shifting range margins, thereby promoting adaptation towards a range-expansion phenotype. Here, we use individual-based simulations to study the surfing statistics of recurrent beneficial mutations on wave-like range expansions in linear habitats. We show that the rate of surfing depends on two strongly antagonistic factors, the probability of surfing given the spatial location of a novel mutation and the rate of occurrence of mutations at that location. The surfing probability strongly increases towards the tip of the wave. Novel mutations are unlikely to surf unless they enjoy a spatial head start compared to the bulk of the population. The needed head start is shown to be proportional to the inverse fitness of the mutant type, and only weakly dependent on the carrying capacity. The precise location dependence of surfing probabilities is derived from the non-extinction probability of a branching process within a moving field of growth rates. The second factor is the mutation occurrence which strongly decreases towards the tip of the wave. Thus, most successful mutations arise at an intermediate position in the front of the wave. We present an analytic theory for the tradeoff between these factors that allows to predict how frequently substitutions by beneficial mutations occur at invasion fronts. We find that small amounts of genetic drift increase the fixation rate of beneficial mutations at the advancing front, and thus could be important for adaptation during species invasions. PMID:22479175

Aerobic Exercise Training Reduces Cannabis Craving and Use in Non-Treatment Seeking Cannabis-Dependent Adults

PubMed Central

Buchowski, Maciej S.; Meade, Natalie N.; Charboneau, Evonne; Park, Sohee; Dietrich, Mary S.; Cowan, Ronald L.; Martin, Peter R.

2011-01-01

Background Cannabis dependence is a significant public health problem. Because there are no approved medications for this condition, treatment must rely on behavioral approaches empirically complemented by such lifestyle change as exercise. Aims To examine the effects of moderate aerobic exercise on cannabis craving and use in cannabis dependent adults under normal living conditions. Design Participants attended 10 supervised 30-min treadmill exercise sessions standardized using heart rate (HR) monitoring (60–70% HR reserve) over 2 weeks. Exercise sessions were conducted by exercise physiologists under medical oversight. Participants Sedentary or minimally active non-treatment seeking cannabis-dependent adults (n = 12, age 25±3 years, 8 females) met criteria for primary cannabis dependence using the Substance Abuse module of the Structured Clinical Interview for DSM-IV (SCID). Measurements Self-reported drug use was assessed for 1-week before, during, and 2-weeks after the study. Participants viewed visual cannabis cues before and after exercise in conjunction with assessment of subjective cannabis craving using the Marijuana Craving Questionnaire (MCQ-SF). Findings Daily cannabis use within the run-in period was 5.9 joints per day (SD = 3.1, range 1.8–10.9). Average cannabis use levels within the exercise (2.8 joints, SD = 1.6, range 0.9–5.4) and follow-up (4.1 joints, SD = 2.5, range 1.1–9.5) periods were lower than during the run-in period (both P<.005). Average MCQ factor scores for the pre- and post-exercise craving assessments were reduced for compulsivity (P  = .006), emotionality (P  = .002), expectancy (P  = .002), and purposefulness (P  = .002). Conclusions The findings of this pilot study warrant larger, adequately powered controlled trials to test the efficacy of prescribed moderate aerobic exercise as a component of cannabis dependence treatment. The neurobiological mechanisms that account for these beneficial effects on cannabis use may lead to understanding of the physical and emotional underpinnings of cannabis dependence and recovery from this disorder. Trial Registration ClinicalTrials.gov NCT00838448] PMID:21408154

Temperature dependent charge transport in poly(3-hexylthiophene) diodes

NASA Astrophysics Data System (ADS)

Rahaman, Abdulla Bin; Sarkar, Atri; Banerjee, Debamalya

2018-04-01

In this work, we present charge transport properties of poly(3-hexylthiophene) (P3HT) diodes under dark conditions. Temperature dependent current-voltage (J-V) characteristics shows that charge transport represents a transition from ohomic to trap limited current. The forward current density obeys a power law J˜Vm, m>2 represents the space charge limited current region in presence of traps within the band gap. Frequency dependent conductivity has been studied in a temperature range 150K-473K. The dc conductivity values show Arrhenius like behavior and it gives conductivity activation energy 223 meV. Temperature dependent conductivity indicates a thermodynamic transition of our system.

Heat capacities and volumetric changes in the glass transition range: a constitutive approach based on the standard linear solid

NASA Astrophysics Data System (ADS)

Lion, Alexander; Mittermeier, Christoph; Johlitz, Michael

2017-09-01

A novel approach to represent the glass transition is proposed. It is based on a physically motivated extension of the linear viscoelastic Poynting-Thomson model. In addition to a temperature-dependent damping element and two linear springs, two thermal strain elements are introduced. In order to take the process dependence of the specific heat into account and to model its characteristic behaviour below and above the glass transition, the Helmholtz free energy contains an additional contribution which depends on the temperature history and on the current temperature. The model describes the process-dependent volumetric and caloric behaviour of glass-forming materials, and defines a functional relationship between pressure, volumetric strain, and temperature. If a model for the isochoric part of the material behaviour is already available, for example a model of finite viscoelasticity, the caloric and volumetric behaviour can be represented with the current approach. The proposed model allows computing the isobaric and isochoric heat capacities in closed form. The difference c_p -c_v is process-dependent and tends towards the classical expression in the glassy and equilibrium ranges. Simulations and theoretical studies demonstrate the physical significance of the model.

Investigation of temperature-dependent photoluminescence in multi-quantum wells.

PubMed

Fang, Yutao; Wang, Lu; Sun, Qingling; Lu, Taiping; Deng, Zhen; Ma, Ziguang; Jiang, Yang; Jia, Haiqiang; Wang, Wenxin; Zhou, Junming; Chen, Hong

2015-07-31

Photoluminescence (PL) is a nondestructive and powerful method to investigate carrier recombination and transport characteristics in semiconductor materials. In this study, the temperature dependences of photoluminescence of GaAs-AlxGa1-xAs multi-quantum wells samples with and without p-n junction were measured under both resonant and non-resonant excitation modes. An obvious increase of photoluminescence(PL) intensity as the rising of temperature in low temperature range (T < 50 K), is observed only for GaAs-AlxGa1-xAs quantum wells sample with p-n junction under non-resonant excitation. The origin of the anomalous increase of integrated PL intensity proved to be associated with the enhancement of carrier drifting because of the increase of carrier mobility in the temperature range from 15 K to 100 K. For non-resonant excitation, carriers supplied from the barriers will influence the temperature dependence of integrated PL intensity of quantum wells, which makes the traditional methods to acquire photoluminescence characters from the temperature dependence of integrated PL intensity unavailable. For resonant excitation, carriers are generated only in the wells and the temperature dependence of integrated PL intensity is very suitable to analysis the photoluminescence characters of quantum wells.

Threshold and Beyond: Modeling The Intensity Dependence of Auditory Responses

PubMed Central

2007-01-01

In many studies of auditory-evoked responses to low-intensity sounds, the response amplitude appears to increase roughly linearly with the sound level in decibels (dB), corresponding to a logarithmic intensity dependence. But the auditory system is assumed to be linear in the low-intensity limit. The goal of this study was to resolve the seeming contradiction. Based on assumptions about the rate-intensity functions of single auditory-nerve fibers and the pattern of cochlear excitation caused by a tone, a model for the gross response of the population of auditory nerve fibers was developed. In accordance with signal detection theory, the model denies the existence of a threshold. This implies that regarding the detection of a significant stimulus-related effect, a reduction in sound intensity can always be compensated for by increasing the measurement time, at least in theory. The model suggests that the gross response is proportional to intensity when the latter is low (range I), and a linear function of sound level at higher intensities (range III). For intensities in between, it is concluded that noisy experimental data may provide seemingly irrefutable evidence of a linear dependence on sound pressure (range II). In view of the small response amplitudes that are to be expected for intensity range I, direct observation of the predicted proportionality with intensity will generally be a challenging task for an experimenter. Although the model was developed for the auditory nerve, the basic conclusions are probably valid for higher levels of the auditory system, too, and might help to improve models for loudness at threshold. PMID:18008105

Temperature Dependence of the Luminescence Decay Time of a PbWO4 Scintillator

NASA Astrophysics Data System (ADS)

Shi, Chao-shu; Deng, Jie; Han, Zheng-fu; Xie, Zhi-jian; Liao, Jing-ying; G, Zimmerer; J, Beker; M, Kamada; M, Runne; A, Schröder

1998-06-01

Experimental results are given for the temperature dependence of the decay time of the emission at 430 nm from PbWO4 crystal under vacuum-ultraviolet (82 nm) photon excitation in the temperature range of 80-300 K. The structures in the curve are interpreted for the first time by studying the thermoluminescence of PbWO4, which originates from the traps in the crystal.

Frequency dependent Lg attenuation in south-central Alaska

USGS Publications Warehouse

McNamara, D.E.

2000-01-01

The characteristics of seismic energy attenuation are determined using high frequency Lg waves from 27 crustal earthquakes, in south-central Alaska. Lg time-domain amplitudes are measured in five pass-bands and inverted to determine a frequency-dependent quality factor, Q(f), model for south-central Alaska. The inversion in this study yields the frequency-dependent quality factor, in the form of a power law: Q(f) = Q0fη = 220(±30) f0.66(±0.09) (0.75≤f≤12Hz). The results from this study are remarkably consistent with frequency dependent quality factor estimates, using local S-wave coda, in south-central Alaska. The consistency between S-coda Q(f) and Lg Q(f) enables constraints to be placed on the mechanism of crustal attenuation in south-central Alaska. For the range of frequencies considered in this study both scattering and intrinsic attenuation mechanisms likely play an equal role.

Employee performance in the knowledge economy: Capturing the keys to success

PubMed Central

Fauth, Rebecca; Bevan, Stephen; Mills, Peter

2009-01-01

The present study examines the key determinants of employee performance in a knowledge-intensive service firm located in the UK. Using data from a pilot study, we mapped eight performance-related behaviors to two measures of global performance to isolate the strongest predictors of the latter. We also examined the degree to which these associations varied depending on whether employees or their managers reported on performance as well as according to the degree of complexity (eg, ongoing learning, multitasking, problem solving, etc.) present in workers’ jobs. Findings revealed that more traditional employee performance-related behaviors (eg, dependability) as well as behaviors that have likely increased in importance in the knowledge economy (eg, sharing ideas and information) accounted for the most variance in reported global performance. Sharing ideas and information was a particularly important predictor for workers in complex jobs. When the performance-related behaviors were regressed on the organization’s annual employee appraisal ratings, only dependability and time management behaviors were significantly associated with the outcome. As organizational success increasingly is dependent on intangible inputs stemming from the ideas, innovations and creativity of its workforce, organizations need to ensure that they are capturing the full range of behaviors that help to define their success. Further research with a diverse range of organizations will help define this further. PMID:22110316

Magnetic Levitation Force Measurement System at Any Low Temperatures From 20 K To 300 K

NASA Astrophysics Data System (ADS)

Celik, Sukru; Guner, S. Baris; Coskun, Elvan

2015-03-01

Most of the magnetic levitation force measurements in previous studies were performed at liquid nitrogen temperatures. For the levitation force of MgB2 and iron based superconducting samples, magnetic levitation force measurement system is needed. In this study, magnetic levitation force measurement system was designed. In this system, beside vertical force versus vertical motion, lateral and vertical force versus lateral motion measurements, the vertical force versus temperature at the fixed distance between permanent magnet PM - superconducting sample SS and the vertical force versus time measurements were performed at any temperatures from 20 K to 300 K. Thanks to these measurements, the temperature dependence, time dependence, and the distance (magnetic field) and temperature dependences of SS can be investigated. On the other hand, the magnetic stiffness MS measurements can be performed in this system. Using the measurement of MS at different temperature in the range, MS dependence on temperature can be investigated. These measurements at any temperatures in the range help to the superconductivity properties to be characterized. This work was supported by TUBTAK-the Scientific and technological research council of Turkey under project of MFAG - 110T622. This system was applied to the Turkish patent institute with the Application Number of 2013/13638 on 22/11/2013.

Turbine blade unsteady aerodynamic loading and heat transfer

NASA Astrophysics Data System (ADS)

Johnston, David Alan

Stator indexing to minimize the unsteady aerodynamic loading of closely spaced airfoil rows in turbomachinery is a new technique for the passive control of flow-induced vibrations. This technique, along with the effects of steady blade loading, were studied by means of experiments performed in a two-stage low-speed research turbine. With the second vane row fixed, the inlet vane row was indexed to six positions over one vane-pitch cycle for a range of stage loadings. The aerodynamic forcing function to the first-stage rotor was measured in the rotating reference frame, with the resulting rotor blade unsteady aerodynamic response quantified by rotor blades instrumented with dynamic pressure transducers. Reductions in the unsteady lift magnitude were achieved at all turbine operating conditions, with attenuation ranging from 37% to 74% of the maximum unsteady lift. Additionally, in complementary experiments, the effects of stator indexing and steady blade loading on the unsteady heat transfer of the first- and second-stage rotors was studied for the design and highest blade loading conditions using platinum-film heat gages. The attenuation of unsteady heat transfer coefficient was blade-loading dependent and location dependent along the chord and span, ranging 10% to 90% of maximum. Due to the high degree of location dependence of attenuation, stator indexing is therefore best suited to minimize unsteady heat transfer in local hot spots of the blade rather than the blade as a whole.

Surface response of a fractional order viscoelastic halfspace to surface and subsurface sources

PubMed Central

Meral, F. Can; Royston, Thomas J.; Magin, Richard L.

2009-01-01

Previous studies by the second author published in this journal focused on low audible frequency (40–400 Hz) shear and surface wave motion in and on a viscoelastic material representative of biological tissue. Specific cases considered were that of surface wave motion on a halfspace caused by a finite rigid circular disk located on the surface and oscillating normal to it [Royston et al., J. Acoust. Soc. Am. 106, 3678–3686 (1999)] and compression, shear, and surface wave motion in a halfspace generated by a subsurface finite dipole [Royston et al., J. Acoust. Soc. Am. 113, 1109–1121 (2003)]. In both studies, a Voigt model of viscoelasticity was assumed in the theoretical treatment, which resulted in agreement between theoretical predictions and experimental measurements over a limited frequency range. In the present article, the linear viscoelastic assumption in these two prior works is revisited to consider a (still linear) fractional order Voigt model, where the rate-dependent damping component that is dependent on the first derivative of time is replaced with a component that is dependent on a fractional derivative of time. It is shown that in both excitation source configurations, the fractional order Voigt model assumption improves the match of theory to experiment over a wider frequency range (in some cases up to the measured range of 700 Hz). PMID:20000941

Determination of Age-Dependent Reference Ranges for Coagulation Tests Performed Using Destiny Plus

PubMed Central

Arslan, Fatma Demet; Serdar, Muhittin; Merve Ari, Elif; Onur Oztan, Mustafa; Hikmet Kozcu, Sureyya; Tarhan, Huseyin; Cakmak, Ozgur; Zeytinli, Merve; Yasar Ellidag, Hamit

2016-01-01

Background In order to apply the right treatment for hemostatic disorders in pediatric patients, laboratory data should be interpreted with age-appropriate reference ranges. Objectives The purpose of this study was to determining age-dependent reference range values for prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen tests, and D-dimer tests. Materials and Methods A total of 320 volunteers were included in the study with the following ages: 1 month - 1 year (n = 52), 2 - 5 years (n = 50), 6 - 10 years (n = 48), 11 - 17 years (n = 38), and 18 - 65 years (n = 132). Each volunteer completed a survey to exclude hemostatic system disorder. Using a nonparametric method, the lower and upper limits, including 95% distribution and 90% confidence intervals, were calculated. Results No statistically significant differences were found between PT and aPTT values in the groups consisting of children. Thus, the reference ranges were separated into child and adult age groups. PT and aPTT values were significantly higher in the children than in the adults. Fibrinogen values in the 6 - 10 age group and the adult age group were significantly higher than in the other groups. D-dimer levels were significantly lower in those aged 2 - 17; thus, a separate reference range was established. Conclusions These results support other findings related to developmental hemostasis, confirming that adult and pediatric age groups should be evaluated using different reference ranges. PMID:27617078

Scale-dependent diffusion anisotropy in nanoporous silicon

PubMed Central

Kondrashova, Daria; Lauerer, Alexander; Mehlhorn, Dirk; Jobic, Hervé; Feldhoff, Armin; Thommes, Matthias; Chakraborty, Dipanjan; Gommes, Cedric; Zecevic, Jovana; de Jongh, Petra; Bunde, Armin; Kärger, Jörg; Valiullin, Rustem

2017-01-01

Nanoporous silicon produced by electrochemical etching of highly B-doped p-type silicon wafers can be prepared with tubular pores imbedded in a silicon matrix. Such materials have found many technological applications and provide a useful model system for studying phase transitions under confinement. This paper reports a joint experimental and simulation study of diffusion in such materials, covering displacements from molecular dimensions up to tens of micrometers with carefully selected probe molecules. In addition to mass transfer through the channels, diffusion (at much smaller rates) is also found to occur in directions perpendicular to the channels, thus providing clear evidence of connectivity. With increasing displacements, propagation in both axial and transversal directions is progressively retarded, suggesting a scale-dependent, hierarchical distribution of transport resistances (“constrictions” in the channels) and of shortcuts (connecting “bridges”) between adjacent channels. The experimental evidence from these studies is confirmed by molecular dynamics (MD) simulation in the range of atomistic displacements and rationalized with a simple model of statistically distributed “constrictions” and “bridges” for displacements in the micrometer range via dynamic Monte Carlo (DMC) simulation. Both ranges are demonstrated to be mutually transferrable by DMC simulations based on the pore space topology determined by electron tomography. PMID:28106047

Condition-dependent sex: who does it, when and why?

PubMed Central

2016-01-01

We review the phenomenon of condition-dependent sex—where individuals' condition affects the likelihood that they will reproduce sexually rather than asexually. In recent years, condition-dependent sex has been studied both theoretically and empirically. Empirical results in microbes, fungi and plants support the theoretical prediction that negative condition-dependent sex, in which individuals in poor condition are more likely to reproduce sexually, can be evolutionarily advantageous under a wide range of settings. Here, we review the evidence for condition-dependent sex and its potential implications for the long-term survival and adaptability of populations. We conclude by asking why condition-dependent sex is not more commonly observed, and by considering generalizations of condition-dependent sex that might apply even for obligate sexuals. This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’. PMID:27619702

Influence of temperature on the spectral characteristics of semiconductor lasers in the visible range

NASA Astrophysics Data System (ADS)

Adamov, A. A.; Baranov, M. S.; Khramov, V. N.

2018-04-01

The results of studies on the effect of temperature on the output spectral characteristics of continuous semiconductor lasers of the visible range are presented. The paper presents the results of studying the spectral-optical radiation parameters of semiconductor lasers, their coherence lengths, and the dependence of the position of the spectral peak of the wavelength on temperature. This is necessary for the selection of the most optimal laser in order to use it for medical ophthalmologic diagnosis. The experiment was carried out using semiconductor laser modules based on a laser diode. The spectra were recorded by using a two-channel automated spectral complex based on the MDR-23 monochromator. Spectral dependences on the temperature of semiconductor lasers are obtained, in the range from 300 to 370 K. The possibility of determining the internal damage to the stabilization of laser modules without opening the case is shown, but only with the use of their spectral characteristics. The obtained data allow taking into account temperature characteristics and further optimization of parameters of such lasers when used in medical practice, in particular, in ophthalmologic diagnostics.

Fish movement and habitat use depends on water body size and shape

USGS Publications Warehouse

Woolnough, D.A.; Downing, J.A.; Newton, T.J.

2009-01-01

Home ranges are central to understanding habitat diversity, effects of fragmentation and conservation. The distance that an organism moves yields information on life history, genetics and interactions with other organisms. Present theory suggests that home range is set by body size of individuals. Here, we analyse estimates of home ranges in lakes and rivers to show that body size of fish and water body size and shape influence home range size. Using 71 studies including 66 fish species on five continents, we show that home range estimates increased with increasing water body size across water body shapes. This contrasts with past studies concluding that body size sets home range. We show that water body size was a consistently significant predictor of home range. In conjunction, body size and water body size can provide improved estimates of home range than just body size alone. As habitat patches are decreasing in size worldwide, our findings have implications for ecology, conservation and genetics of populations in fragmented ecosystems. ?? 2008 Blackwell Munksgaard.

Characteristics of an OSLD in the diagnostic energy range

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

Al-Senan, Rani M.; Hatab, Mustapha R.

2011-07-15

Purpose: Optically stimulated luminescence (OSL) dosimetry has been recently introduced in radiation therapy as a potential alternative to the thermoluminescent dosimeter (TLD) system. The aim of this study was to investigate the feasibility of using OSL point dosimeters in the energy range used in diagnostic imaging. Methods: NanoDot OSL dosimeters (OSLDs) were used in this study, which started with testing the homogeneity of a new packet of nanoDots. Reproducibility and the effect of optical treatment (bleaching) were then examined, followed by an investigation of the effect of accumulated dose on the OSLD indicated doses. OSLD linearity, angular dependence, and energymore » dependence were also studied. Furthermore, comparison with LiF:Mg,Ti TLD chips using standard CT dose phantoms at 80 and 120 kVp settings was performed. Results: Batch homogeneity showed a coefficient of variation of <5%. Single-irradiation measurements with bleaching after each OSL readout was found to be associated with a 3.3% reproducibility (one standard deviation measured with a 8 mGy test dose), and no systematic change in OSLDs sensitivity could be noted from measurement to measurement. In contrast, the multiple-irradiation readout without bleaching in between measurements was found to be associated with an uncertainty (using a 6 mGy test dose) that systematically increased with accumulated dose, reaching 42% at 82 mGy. Good linearity was shown by nanoDots under general x-ray, CT, and mammography units with an R{sup 2} > 0.99. The angular dependence test showed a drop of approximately 70% in the OSLD response at 90 deg. in mammography (25 kVp). With the general radiography unit, the maximum drop was 40% at 80 kVp and 20% at 120 kVp, and it was only 10% with CT at both 80 and 120 kVp. The energy dependence study showed a range of ion chamber-to-OSLDs ratios between 0.81 and 1.56, at the energies investigated (29-62 keV). A paired t-test for comparing the OSLDs and TLDs showed no significant variation (p > 0.1). Conclusions: OSLDs exhibited good batch homogeneity (<5%) and reproducibility (3.3%), as well as a linear response. In addition, they showed no statistically significant difference with TLDs in CT measurements (p > 0.1). However, high uncertainty (42%) in the dose estimate was found as a result of relatively high accumulated dose. Furthermore, nanoDots showed high angular dependence (up to 70%) in low kVp techniques. Energy dependence of about 60% was found, and correction factors were suggested for the range of energies investigated. Therefore, if angular and energy dependences are taken into consideration and the uncertainty associated with accumulated dose is avoided, OSLDs (nanoDots) can be suitable for use as point dosimeters in diagnostic settings.« less

Functional dependence of resonant harmonics on nanomechanical parameters in dynamic mode atomic force microscopy.

PubMed

Gramazio, Federico; Lorenzoni, Matteo; Pérez-Murano, Francesc; Rull Trinidad, Enrique; Staufer, Urs; Fraxedas, Jordi

2017-01-01

We present a combined theoretical and experimental study of the dependence of resonant higher harmonics of rectangular cantilevers of an atomic force microscope (AFM) as a function of relevant parameters such as the cantilever force constant, tip radius and free oscillation amplitude as well as the stiffness of the sample's surface. The simulations reveal a universal functional dependence of the amplitude of the 6th harmonic (in resonance with the 2nd flexural mode) on these parameters, which can be expressed in terms of a gun-shaped function. This analytical expression can be regarded as a practical tool for extracting qualitative information from AFM measurements and it can be extended to any resonant harmonics. The experiments confirm the predicted dependence in the explored 3-45 N/m force constant range and 2-345 GPa sample's stiffness range. For force constants around 25 N/m, the amplitude of the 6th harmonic exhibits the largest sensitivity for ultrasharp tips (tip radius below 10 nm) and polymers (Young's modulus below 20 GPa).

On the temperature dependence of flammability limits of gases.

PubMed

Kondo, Shigeo; Takizawa, Kenji; Takahashi, Akifumi; Tokuhashi, Kazuaki

2011-03-15

Flammability limits of several combustible gases were measured at temperatures from 5 to 100 °C in a 12-l spherical flask basically following ASHRAE method. The measurements were done for methane, propane, isobutane, ethylene, propylene, dimethyl ether, methyl formate, 1,1-difluoroethane, ammonia, and carbon monoxide. As the temperature rises, the lower flammability limits are gradually shifted down and the upper limits are shifted up. Both the limits shift almost linearly to temperature within the range examined. The linear temperature dependence of the lower flammability limits is explained well using a limiting flame temperature concept at the lower concentration limit (LFL)--'White's rule'. The geometric mean of the flammability limits has been found to be relatively constant for many compounds over the temperature range studied (5-100 °C). Based on this fact, the temperature dependence of the upper flammability limit (UFL) can be predicted reasonably using the temperature coefficient calculated for the LFL. However, some compounds such as ethylene and dimethyl ether, in particular, have a more complex temperature dependence. Copyright © 2011 Elsevier B.V. All rights reserved.

Characterization of glutamate decarboxylase from Lactobacillus plantarum and its C-terminal function for the pH dependence of activity.

PubMed

Shin, Sun-Mi; Kim, Hana; Joo, Yunhye; Lee, Sang-Jae; Lee, Yong-Jik; Lee, Sang Jun; Lee, Dong-Woo

2014-12-17

The gadB gene encoding glutamate decarboxylase (GAD) from Lactobacillus plantarum was cloned and expressed in Escherichia coli. The recombinant enzyme exhibited maximal activity at 40 °C and pH 5.0. The 3D model structure of L. plantarum GAD proposed that its C-terminal region (Ile454-Thr468) may play an important role in the pH dependence of catalysis. Accordingly, C-terminally truncated (Δ3 and Δ11 residues) mutants were generated and their enzyme activities compared with that of the wild-type enzyme at different pH values. Unlike the wild-type GAD, the mutants showed pronounced catalytic activity in a broad pH range of 4.0-8.0, suggesting that the C-terminal region is involved in the pH dependence of GAD activity. Therefore, this study may provide effective target regions for engineering pH dependence of GAD activity, thereby meeting industrial demands for the production of γ-aminobutyrate in a broad range of pH values.

Drug dependence associated with triptans and ergot derivatives: a case/non-case study.

PubMed

Beau-Salinas, Frédérique; Jonville-Béra, Annie Pierre; Cissoko, Haware; Bensouda-Grimaldi, Lamiae; Autret-Leca, Elisabeth

2010-04-01

The aim of this case/non-case study was to assess and compare the risk of drug dependence associated with different migraine-specific drugs, i.e., ergot derivatives and triptans, using the French pharmacovigilance database. Reports on drug side effects recorded in this database between January 1985 and June 2007 were analyzed, and triptans (almotriptan, eletriptan, naratriptan, sumatriptan, and zolmitriptan) as well as ergot derivatives used in acute migraine were examined. For all reports, cases were defined as those reports corresponding to "drug abuse," "physical or mental drug dependence," and "pharmacodependence," whereas "non-cases" were defined as all the remaining SED reports. The method's reliability was assessed by calculating the risk associated with a negative (amoxicillin) and a positive (benzodiazepines) control. The risk of dependence associated with each drug and control was evaluated by calculating the odds ratio (OR) with a confidence interval of 95%. Among the 309,178 reports recorded in the database, drug dependence accounted for 0.8% (2,489) of the reports, with 10.9% (449) involving a triptan, and 9.33% (332) an ergot derivative. The risk of dependence was similar for triptans and ergot derivatives and did not differ from that of benzodiazepines. In the triptan group, the risk (odds ratio [95% CI]) ranged from 10.3 [4.8-22.3] for sumatriptan to 21.5 for eletriptan [10.1-45.6], while in the ergot derivative group, it ranged from 12 [8-17.9] for ergotamine to 20.6 [8-53] for dihydroergotamine. These findings confirm the hypothesis that triptans and ergot derivatives are associated with an increased risk of drug dependence.

Laboratory observations of temperature and humidity dependencies of nucleation and growth rates of sub-3 nm particles

NASA Astrophysics Data System (ADS)

Yu, Huan; Dai, Liang; Zhao, Yi; Kanawade, Vijay P.; Tripathi, Sachchida N.; Ge, Xinlei; Chen, Mindong; Lee, Shan-Hu

2017-02-01

Temperature and relative humidity (RH) are the most important thermodynamic parameters in aerosol formation, yet laboratory studies of nucleation and growth dependencies on temperature and RH are lacking. Here we report the experimentally observed temperature and RH dependences of sulfuric acid aerosol nucleation and growth. Experiments were performed in a flow tube in the temperature range from 248 to 313 K, RH from 0.8% to 79%, and relative acidity (RA) of sulfuric acid from 6 × 10-5 to 0.38 (2 × 107-109 cm-3). The impurity levels of base compounds were determined to be NH3 < 23 pptv (parts per thousand by volume), methylamine < 1.5 pptv, and dimethylamine < 0.52 pptv. Our results showed that low temperatures favor nucleation at fixed sulfuric acid concentration but impede nucleation when RA is fixed. It is also shown that binary nucleation of sulfuric acid and water is negligible in planetary boundary layer temperature and sulfuric acid ranges. An empirical algorithm was derived to correlate the nucleation rate with RA, RH, and temperature together. Collision-limited condensation of free-sulfuric acid molecules fails to predict the observed growth rate in the sub-3 nm size range, as well as its dependence on temperature and RH. This suggests that evaporation, sulfuric acid hydration, and possible involvement of other ternary molecules should be considered for the sub-3 nm particle growth.

Kinetics of silicide formation over a wide range of heating rates spanning six orders of magnitude

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

Molina-Ruiz, Manel; Lopeandía, Aitor F.; Gonzalez-Silveira, Marta

Kinetic processes involving intermediate phase formation are often assumed to follow an Arrhenius temperature dependence. This behavior is usually inferred from limited data over narrow temperature intervals, where the exponential dependence is generally fully satisfied. However, direct evidence over wide temperature intervals is experimentally challenging and data are scarce. Here, we report a study of silicide formation between a 12 nm film of palladium and 15 nm of amorphous silicon in a wide range of heating rates, spanning six orders of magnitude, from 0.1 to 10{sup 5 }K/s, or equivalently more than 300 K of variation in reaction temperature. The calorimetric traces exhibit severalmore » distinct exothermic events related to interdiffusion, nucleation of Pd{sub 2}Si, crystallization of amorphous silicon, and vertical growth of Pd{sub 2}Si. Interestingly, the thickness of the initial nucleation layer depends on the heating rate revealing enhanced mass diffusion at the fastest heating rates during the initial stages of the reaction. In spite of this, the formation of the silicide strictly follows an Arrhenius temperature dependence over the whole temperature interval explored. A kinetic model is used to fit the calorimetric data over the complete heating rate range. Calorimetry is complemented by structural analysis through transmission electron microscopy and both standard and in-situ synchrotron X-ray diffraction.« less

Phylogenetic analysis of Columbid herpesvirus-1 in rock pigeons, birds of prey and non-raptorial birds in Poland

PubMed Central

2013-01-01

Background The identity of herpesviruses isolated in Europe from domestic pigeons (Columbid herpesvirus-1 - CoHV-1) as well as falcons and owls remains unknown. All these herpesviruses are antigenically and genetically related. The falcons and owls are thought to have become infected during the ingestion of pigeon meat thus suggesting the virus’s capacity to infect a wide range of hosts. The aim of the conducted study was to detect the occurrence of CoHV-1 and estimating the similarities and differences in the DNA-dependent DNA polymerase gene of herpesviruses isolated from domestic pigeons, birds of prey and non-raptorial free-ranging birds in Poland. Results The study has shown the presence of CoHV-1 in 20.4% (18/88) in the examined birds. In case of one CoHV-1, infected Peregrine Falcon (Falco peregrinus), neurological signs were observed. Nucleotide sequencing of the DNA-dependent DNA polymerase gene, showed a high similarity among Polish strains (100%), independently from the species of the affected birds. Only one compared CoHV-1 strain - KP 21/23 originating from Germany showed a slightly lower similarity at a level of 99.1%. Further analysis has shown the identity of DNA-dependent DNA polymerase of CoHV-1 strains and other herpesviruses present in poultry as well as other birds ranged from 35.4 to 44.9%. Interestingly CoHV-1 infection was also confirmed for the first time in four non-raptorial birds. Conclusions The current study has shown a high similarity of CoHV-1 strains and the possible transmission of herpesviruses between domestic rock pigeons and free-ranging birds including raptors and non-raptorial birds. Further studies focused on cloning and the analysis of the whole CoHV-1 genome which is needed to explain the role of the observed similarities and differences between field strains of columbid herpesviruses. PMID:23517888

Test Expectancy and Memory for Important Information

ERIC Educational Resources Information Center

Middlebrooks, Catherine D.; Murayama, Kou; Castel, Alan D.

2017-01-01

Prior research suggests that learners study and remember information differently depending upon the type of test they expect to later receive. The current experiments investigate how testing expectations impact the study of and memory for valuable information. Participants studied lists of words ranging in value from 1 to 10 points with the goal…

Orientational order as the origin of the long-range hydrophobic effect.

PubMed

Banerjee, Saikat; Singh, Rakesh S; Bagchi, Biman

2015-04-07

The long range attractive force between two hydrophobic surfaces immersed in water is observed to decrease exponentially with their separation-this distance-dependence of effective force is known as the hydrophobic force law (HFL). We explore the microscopic origin of HFL by studying distance-dependent attraction between two parallel rods immersed in 2D Mercedes Benz model of water. This model is found to exhibit a well-defined HFL. Although the phenomenon is conventionally explained by density-dependent theories, we identify orientation, rather than density, as the relevant order parameter. The range of density variation is noticeably shorter than that of orientational heterogeneity. The latter is comparable to the observed distances of hydrophobic force. At large separation, attraction between the rods arises primarily from a destructive interference among the inwardly propagating oppositely oriented heterogeneity generated in water by the two rods. As the rods are brought closer, the interference increases leading to a decrease in heterogeneity and concomitant decrease in free energy of the system, giving rise to the effective attraction. We notice formation of hexagonal ice-like structures at the onset of attractive region which suggests that metastable free energy minimum may play a role in the origin of HFL.

The thermopower in the temperature range T(sub c)-1000K and the bank spectrum of Bi-based superconductors

NASA Technical Reports Server (NTRS)

Gasumyants, V. E.; Vladimirskaya, E. V.; Smirnov, V. I.; Kazanskiy, S. V.

1995-01-01

The temperature dependencies of thermopower, S, in the range T = T(sub c)-1000K as well as of resistivity and Hall coefficient in the range T = T(sub c)-300K for the single-phase ceramic samples Bi2Sr2Ca(1-x)Nd(x)Cu2O(y) have been measured. It was found that the S(T) dependencies in normal phase have three characteristic regions. Despite the fact that the S(T) dependencies in Bi-based high-T(sub c) superconductors (HTSC) differ essentially from ones in Y-based HTSC at T = T(sub c)-300K, the main feature of theirs (S(T) = const at high temperatures) retains in samples investigated at T is greater than 620K. The results obtained have been analyzed on the basis of the narrow-band model with the use of assumption of slight asymmetry of the conductive band. The band spectrum parameters of the samples studied have been calculated. An analysis of the tendencies in these parameters changes with samples composition varying enables to make the conclusion about the similarity of the main features of the conductive band structure in Y- and Bi-based HTSC.

Orientational order as the origin of the long-range hydrophobic effect

NASA Astrophysics Data System (ADS)

Banerjee, Saikat; Singh, Rakesh S.; Bagchi, Biman

2015-04-01

The long range attractive force between two hydrophobic surfaces immersed in water is observed to decrease exponentially with their separation—this distance-dependence of effective force is known as the hydrophobic force law (HFL). We explore the microscopic origin of HFL by studying distance-dependent attraction between two parallel rods immersed in 2D Mercedes Benz model of water. This model is found to exhibit a well-defined HFL. Although the phenomenon is conventionally explained by density-dependent theories, we identify orientation, rather than density, as the relevant order parameter. The range of density variation is noticeably shorter than that of orientational heterogeneity. The latter is comparable to the observed distances of hydrophobic force. At large separation, attraction between the rods arises primarily from a destructive interference among the inwardly propagating oppositely oriented heterogeneity generated in water by the two rods. As the rods are brought closer, the interference increases leading to a decrease in heterogeneity and concomitant decrease in free energy of the system, giving rise to the effective attraction. We notice formation of hexagonal ice-like structures at the onset of attractive region which suggests that metastable free energy minimum may play a role in the origin of HFL.

Temperature dependence of ice-on-rock friction at realistic glacier conditions

PubMed Central

Savage, H.; Nettles, M.

2017-01-01

Using a new biaxial friction apparatus, we conducted experiments of ice-on-rock friction in order to better understand basal sliding of glaciers and ice streams. A series of velocity-stepping and slide–hold–slide tests were conducted to measure friction and healing at temperatures between −20°C and melting. Experimental conditions in this study are comparable to subglacial temperatures, sliding rates and effective pressures of Antarctic ice streams and other glaciers, with load-point velocities ranging from 0.5 to 100 µm s−1 and normal stress σn = 100 kPa. In this range of conditions, temperature dependences of both steady-state friction and frictional healing are considerable. The friction increases linearly with decreasing temperature (temperature weakening) from μ = 0.52 at −20°C to μ = 0.02 at melting. Frictional healing increases and velocity dependence shifts from velocity-strengthening to velocity-weakening behaviour with decreasing temperature. Our results indicate that the strength and stability of glaciers and ice streams may change considerably over the range of temperatures typically found at the ice–bed interface. This article is part of the themed issue ‘Microdynamics of ice’. PMID:28025297

Spectral dependence of the main parameters of ITE silicon avalanche photodiodes

NASA Astrophysics Data System (ADS)

Wegrzecka, Iwona; Grynglas, Maria; Wegrzecki, Maciej

2001-08-01

New applications for avalanche photodiodes (APDs) as in systems using visible radiation, have prompted the need for the evaluation of detection properties of ITE APDs in the 400 divided by 700 nm spectral range. The paper presents the method and result of studies on the spectral dependence of the gain, dark and noise currents, sensitivity and excess noise factor of ITE APDs. The studies have shown that ITE APDs optimized for the near IR radiation can be effectively applied in the detection of radiation above the 500 nm wavelength.

Cross-sectional and prospective relation of cannabis potency, dosing and smoking behaviour with cannabis dependence: an ecological study.

PubMed

van der Pol, Peggy; Liebregts, Nienke; Brunt, Tibor; van Amsterdam, Jan; de Graaf, Ron; Korf, Dirk J; van den Brink, Wim; van Laar, Margriet

2014-07-01

Increased delta-9-tetrahydrocannabinol (THC) concentrations in cannabis may lead to higher THC exposure, cannabis dependence and treatment need, but users may also adapt the actual intake of THC through reduced inhalation of THC containing smoke (titration). We investigated whether consumers of stronger cannabis use less cannabis per joint or inhale less smoke than those using less potent cannabis and whether these factors predict cannabis dependence severity. Heavy cannabis users (n = 98) brought their own cannabis, rolled a joint and smoked it ad libitum in a naturalistic setting. We analysed the content of the joint, its association with smoking behaviour and the cross-sectional and prospective (1.5-year follow-up) relations between smoking behaviour and cannabis dependence severity (total number of DSM-IV dependence symptoms). THC concentration in cannabis (range 1.10-24.70%) was correlated positively with cannabis dose per joint (b = 0.008, P = 0.01), but the resulting THC concentration per joint (range 0.24-15.72%) was associated negatively with inhalation volume (b = -0.05, P = 0.03). Smoking behaviour measures (number of puffs, inhaled volume, reduction of puff volume and puff duration while smoking) predicted follow-up dependence severity, independently of baseline dependence severity and monthly THC dose (number of joints × cannabis dose × cannabis THC concentration). Monthly THC dose only predicted follow-up dependence severity when unadjusted for baseline severity. Cannabis users titrate their delta-9-tetrahydrocannabinol intake by inhaling lower volumes of smoke when smoking strong joints, but this does not fully compensate for the higher cannabis doses per joint when using strong cannabis. Thus, users of more potent cannabis are generally exposed to more delta-9-tetrahydrocannabinol. Smoking behaviour appears to be a stronger predictor for cannabis dependence severity than monthly delta-9-tetrahydrocannabinol dose. © 2014 Society for the Study of Addiction.

Range degradation and distal edge behavior of proton radiotherapy beams using 11C activation and Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Elmekawy, Ahmed Farouk

The distal edge of therapeutic proton radiation beams was investigated by different methods. Proton beams produced at the Hampton University Proton Therapy Institute (HUPTI) were used to irradiate a Polymethylmethacrylate (PMMA) phantom for three different ranges (13.5, 17.0 and 21.0 cm) to investigate the distal slope dependence of the Bragg peak. The activation of 11 C was studied by scanning the phantom less than 10 minutes post-irradiation with a Philips Big Bore Gemini(c) PET/CT. The DICOM images were imported into the Varian Eclipse(c) Treatment Planning System (TPS) for analysis and then analyzed by ImageJ(c) . The distal slope ranged from ?0.1671 +/- 0.0036 to -0.1986 +/- 0.0052 (pixel intensity/slice number) for ranges 13.5 to 21.0 cm respectively. A realistic description of the setup was modeled using the GATE 7.0 Monte Carlo simulation tool and compared to the experiment data. The results show the distal slope ranged from -0.1158+/-0.0133 to -0.0787+/-0.002 (Gy/mm). Additionally, low activity, 11C were simulated to study the 11C reconstructed half-life dependence versus the initial activity for six ranges chosen around the previous activation study. The results of the expected/nominal half-life vs. activity ranged from -5 x 10-4 +/- 2.8104 x 10-4 to 1.6 x 10-3 +/- 9.44 x 10-4 (%diff./Bq). The comparison between two experiments with proton beams on a PMMA phantom and multi-layer ion chamber, and two GATE simulations of a proton beam incident on a water phantom and 11C PET study show that: (i) the distal fall-off variation of the steepness of the slopes are found to be similar thus validating the sensitivity of the PET technique to the range degradation and (ii) the average of the super-ratios difference between all studies observed is primarily due to the difference in the dose deposited in the media.

Trends in currency’s return

NASA Astrophysics Data System (ADS)

Tan, A.; Shahrill, M.; Daud, S.; Leung, E.

2018-03-01

The purpose of this paper is to show that short-ranged dependence prevailed for Singapore-Malaysia exchange. Although, it is perceived that there is some evidence of long-ranged dependence [1,2], it is still unclear whether Singapore-Malaysia exchange indeed exhibits long-ranged dependence. For this paper, we focus on the currency rate for a sixteen-year period ranging from September 2002 to September 2017. We estimate the Hurst parameter using the famous rescaled R/S statistics technique. From our analysis, we showed that the Hurst parameter is approximately 0.5 which indicates short-ranged dependence. This short memory property is further validated by performing a one-tailed z-test whose alternative hypothesis is that the Hurst parameter is not 0.5 at 1% significance level. We conclude that the alternative hypothesis is rejected. The existence of short memory proves that the behaviour of the exchange rate is unpredictable, supporting the efficient market hypothesis, which states that not only is price movement completely random but also tomorrow’s prices are predicted by all the information in today’s prices.

The photogrammetric recording of historic transportation sites.

DOT National Transportation Integrated Search

1983-01-01

The purpose of this study was to evaluate the applicability and accuracy of documentation drawings prepared from close-range me terrestrial photogrammetry and to compare them with the results of traditional documentation techniques which depend on ha...

Reynolds number dependence of relative dispersion statistics in isotropic turbulence

NASA Astrophysics Data System (ADS)

Sawford, Brian L.; Yeung, P. K.; Hackl, Jason F.

2008-06-01

Direct numerical simulation results for a range of relative dispersion statistics over Taylor-scale Reynolds numbers up to 650 are presented in an attempt to observe and quantify inertial subrange scaling and, in particular, Richardson's t3 law. The analysis includes the mean-square separation and a range of important but less-studied differential statistics for which the motion is defined relative to that at time t =0. It seeks to unambiguously identify and quantify the Richardson scaling by demonstrating convergence with both the Reynolds number and initial separation. According to these criteria, the standard compensated plots for these statistics in inertial subrange scaling show clear evidence of a Richardson range but with an imprecise estimate for the Richardson constant. A modified version of the cube-root plots introduced by Ott and Mann [J. Fluid Mech. 422, 207 (2000)] confirms such convergence. It has been used to yield more precise estimates for Richardson's constant g which decrease with Taylor-scale Reynolds numbers over the range of 140-650. Extrapolation to the large Reynolds number limit gives an asymptotic value for Richardson's constant in the range g =0.55-0.57, depending on the functional form used to make the extrapolation.

Evidence of b-jet quenching in PbPb collisions at √(s(NN))=2.76  TeV.

PubMed

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Cepeda, M; Dasu, S; Duric, S; Friis, E; Grothe, M; Hall-Wilton, R; Herndon, M; Hervé, A; Klabbers, P; Klukas, J; Lanaro, A; Levine, A; Loveless, R; Mohapatra, A; Ojalvo, I; Perry, T; Pierro, G A; Polese, G; Ross, I; Sakharov, A; Sarangi, T; Savin, A; Smith, W H

2014-09-26

The production of jets associated to bottom quarks is measured for the first time in PbPb collisions at a center-of-mass energy of 2.76 TeV per nucleon pair. Jet spectra are reported in the transverse momentum (p(T)) range of 80-250  GeV/c, and within pseudorapidity |η|<2. The nuclear modification factor (R(AA)) calculated from these spectra shows a strong suppression in the b-jet yield in PbPb collisions relative to the yield observed in pp collisions at the same energy. The suppression persists to the largest values of p(T) studied, and is centrality dependent. The R(AA) is about 0.4 in the most central events, similar to previous observations for inclusive jets. This implies that jet quenching does not have a strong dependence on parton mass and flavor in the jet p(T) range studied.

Plateau on temperature dependence of magnetization of nanostructured rare earth titanates

NASA Astrophysics Data System (ADS)

Rinkevich, A. B.; Korolev, A. V.; Samoylovich, M. I.; Demokritov, S. O.; Perov, D. V.

2018-05-01

Magnetic properties of nanocomposite materials containing particles of rare earth titanates of R2Ti2O7 type, where R is a rare earth ion, including "spin ice" materials are investigated. The descending branches of hysteresis loop have been studied in detail in temperature range from 2 to 50 K. It has been shown that nanocomposites with Yb2Ti2O7, Dy2Ti2O7 and Er2Ti2O7 particles have one intersection point of the descending branches in some temperature range unlike many other nanocomposites. It is shown that magnetization has only weak temperature dependence near this point. It has been obtained that nanocomposites with Pr2Ti2O7 and Nd2Ti2O7 particles have no hysteresis loop. All above findings point out to unusual magnetic structures of the studied samples.

Indentation Size Effect on the Creep Behavior of a SnAgCu Solder

NASA Astrophysics Data System (ADS)

Han, Y. D.; Jing, H. Y.; Nai, S. M. L.; Xu, L. Y.; Tan, C. M.; Wei, J.

In the present study, nanoindentation studies of the 95.8Sn-3.5Ag-0.7Cu lead-free solder were conducted over a range of maximum loads from 20 mN to 100 mN, under a constant ramp rate of 0.05 s-1. The indentation scale dependence of creep behavior was investigated. The results revealed that the creep rate, creep strain rate and indentation stress are all dependent on the indentation depth. As the maximum load increased, an increasing trend in the creep rate was observed, while a decreasing trend in creep strain rate and indentation stress were observed. On the contrary, for the case of stress exponent value, no trend was observed and the values were found to range from 6.16 to 7.38. Furthermore, the experimental results also showed that the creep mechanism of the lead-free solder is dominated by dislocation climb.

Temperature and frequency dependence of ultrasonic attenuation in selected tissues

NASA Technical Reports Server (NTRS)

Gammell, P. M.; Croissette, D. H. L.; Heyser, R. C.

1979-01-01

Ultrasonic attenuation over the frequency range of 1.5-10 MHz has been measured as a function of temperature for porcine liver, backfat, kidney and spleen as well as for a single specimen of human liver. The attenuation in these excised specimens increases nearly linearly with frequency. Over the temperature range of approximately 4-37 C the attenuation decreases with increasing temperature for most soft tissue studied.

Wavelength dependence of ocular damage thresholds in the near-ir to far-ir transition region: proposed revisions to MPES.

PubMed

Zuclich, Joseph A; Lund, David J; Stuck, Bruce E

2007-01-01

This report summarizes the results of a series of infrared (IR) laser-induced ocular damage studies conducted over the past decade. The studies examined retinal, lens, and corneal effects of laser exposures in the near-IR to far-IR transition region (wavelengths from 1.3-1.4 mum with exposure durations ranging from Q-switched to continuous wave). The corneal and retinal damage thresholds are tabulated for all pulsewidth regimes, and the wavelength dependence of the IR thresholds is discussed and contrasted to laser safety standard maximum permissible exposure limits. The analysis suggests that the current maximum permissible exposure limits could be beneficially revised to (1) relax the IR limits over wavelength ranges where unusually high safety margins may unintentionally hinder applications of recently developed military and telecommunications laser systems; (2) replace step-function discontinuities in the IR limits by continuously varying analytical functions of wavelength and pulsewidth which more closely follow the trends of the experimental retinal (for point-source laser exposures) and corneal ED50 threshold data; and (3) result in an overall simplification of the permissible exposure limits over the wavelength range from 1.2-2.6 mum. A specific proposal for amending the IR maximum permissible exposure limits over this wavelength range is presented.

Natural variability of marine ecosystems inferred from a coupled climate to ecosystem simulation

NASA Astrophysics Data System (ADS)

Le Mézo, Priscilla; Lefort, Stelly; Séférian, Roland; Aumont, Olivier; Maury, Olivier; Murtugudde, Raghu; Bopp, Laurent

2016-01-01

This modeling study analyzes the simulated natural variability of pelagic ecosystems in the North Atlantic and North Pacific. Our model system includes a global Earth System Model (IPSL-CM5A-LR), the biogeochemical model PISCES and the ecosystem model APECOSM that simulates upper trophic level organisms using a size-based approach and three interactive pelagic communities (epipelagic, migratory and mesopelagic). Analyzing an idealized (e.g., no anthropogenic forcing) 300-yr long pre-industrial simulation, we find that low and high frequency variability is dominant for the large and small organisms, respectively. Our model shows that the size-range exhibiting the largest variability at a given frequency, defined as the resonant range, also depends on the community. At a given frequency, the resonant range of the epipelagic community includes larger organisms than that of the migratory community and similarly, the latter includes larger organisms than the resonant range of the mesopelagic community. This study shows that the simulated temporal variability of marine pelagic organisms' abundance is not only influenced by natural climate fluctuations but also by the structure of the pelagic community. As a consequence, the size- and community-dependent response of marine ecosystems to climate variability could impact the sustainability of fisheries in a warming world.

Experimental Examination of Intraspecific Density-Dependent Competition during the Breeding Period in Monarch Butterflies (Danaus plexippus)

PubMed Central

Flockhart, D. T. Tyler; Martin, Tara G.; Norris, D. Ryan

2012-01-01

A central goal of population ecology is to identify the factors that regulate population growth. Monarch butterflies (Danaus plexippus) in eastern North America re-colonize the breeding range over several generations that result in population densities that vary across space and time during the breeding season. We used laboratory experiments to measure the strength of density-dependent intraspecific competition on egg laying rate and larval survival and then applied our results to density estimates of wild monarch populations to model the strength of density dependence during the breeding season. Egg laying rates did not change with density but larvae at high densities were smaller, had lower survival, and weighed less as adults compared to lower densities. Using mean larval densities from field surveys resulted in conservative estimates of density-dependent population reduction that varied between breeding regions and different phases of the breeding season. Our results suggest the highest levels of population reduction due to density-dependent intraspecific competition occur early in the breeding season in the southern portion of the breeding range. However, we also found that the strength of density dependence could be almost five times higher depending on how many life-stages were used as part of field estimates. Our study is the first to link experimental results of a density-dependent reduction in vital rates to observed monarch densities in the wild and show that the effects of density dependent competition in monarchs varies across space and time, providing valuable information for developing robust, year-round population models in this migratory organism. PMID:22984614

AC conductivity and dielectric behavior of bulk Furfurylidenemalononitrile

NASA Astrophysics Data System (ADS)

El-Nahass, M. M.; Ali, H. A. M.

2012-06-01

AC conductivity and dielectric behavior for bulk Furfurylidenemalononitrile have been studied over a temperature range (293-333 K) and frequency range (50-5×106 Hz). The frequency dependence of ac conductivity, σac, has been investigated by the universal power law, σac(ω)=Aωs. The variation of the frequency exponent (s) with temperature was analyzed in terms of different conduction mechanisms, and it was found that the correlated barrier hopping (CBH) model is the predominant conduction mechanism. The temperature dependence of σac(ω) showed a linear increase with the increase in temperature at different frequencies. The ac activation energy was determined at different frequencies. Dielectric data were analyzed using complex permittivity and complex electric modulus for bulk Furfurylidenemalononitrile at various temperatures.

Measurements of the size dependence of the concentration of nonvolatile material in fog droplets

NASA Astrophysics Data System (ADS)

Ogren, J. A.; Noone, K. J.; Hallberg, A.; Heintzenberg, J.; Schell, D.; Berner, A.; Solly, I.; Kruisz, C.; Reischl, G.; Arends, B. G.; Wobrock, W.

1992-11-01

Measurements of the size dependence of the mass concentration of nonvolatile material dissolved and suspended in fog droplets were obtained with three complementary approaches, covering a size range from c. 1 50µm diameter: a counterflow virtual impactor, an eight-stage aerosol impactor, and a two-stage fogwater impactor. Concentrations were observed to decrease with size over the entire range, contrary to expectations of increasing concentrations at larger sizes. It is possible that the larger droplets had solute concentrations that increased with increasing size, but that the increase was too weak for the measurements to resolve. Future studies should consider the hypothesis that the droplets were coated with a surface-active substance that hindered their uptake of water.

Temperature-dependent charge transport mechanisms in carbon sphere/polyaniline composite

NASA Astrophysics Data System (ADS)

Nieves, Cesar A.; Martinez, Luis M.; Meléndez, Anamaris; Ortiz, Margarita; Ramos, Idalia; Pinto, Nicholas J.; Zimbovskaya, Natalya

2017-12-01

Charge transport in the temperature range 80 K < T < 300 K was studied in a composite of carbon spheres (CS), prepared via hydrothermal carbonization of sucrose, and the conducting polymer polyaniline (PANi). PANi was synthesized via the oxidative polymerization of aniline with ammonium peroxydisulfate (APS) in acidic media. The CS/PANi composite was prepared by coating the spheres with a thin polyaniline (PANi) film doped with hydrochloric acid (HCl) in situ during the polymerization process. Temperature dependent conductivity measurements show that three dimensional variable range hopping of electrons between polymeric chains in PANi-filled gaps between CS is the predominant transport mechanism through CS/PANi composites. The high conductivity of the CS/PANi composite makes the material attractive for the fabrication of devices and sensors.

Scaling range of power laws that originate from fluctuation analysis

NASA Astrophysics Data System (ADS)

Grech, Dariusz; Mazur, Zygmunt

2013-05-01

We extend our previous study of scaling range properties performed for detrended fluctuation analysis (DFA) [Physica A0378-437110.1016/j.physa.2013.01.049 392, 2384 (2013)] to other techniques of fluctuation analysis (FA). The new technique, called modified detrended moving average analysis (MDMA), is introduced, and its scaling range properties are examined and compared with those of detrended moving average analysis (DMA) and DFA. It is shown that contrary to DFA, DMA and MDMA techniques exhibit power law dependence of the scaling range with respect to the length of the searched signal and with respect to the accuracy R2 of the fit to the considered scaling law imposed by DMA or MDMA methods. This power law dependence is satisfied for both uncorrelated and autocorrelated data. We find also a simple generalization of this power law relation for series with a different level of autocorrelations measured in terms of the Hurst exponent. Basic relations between scaling ranges for different techniques are also discussed. Our findings should be particularly useful for local FA in, e.g., econophysics, finances, or physiology, where the huge number of short time series has to be examined at once and wherever the preliminary check of the scaling range regime for each of the series separately is neither effective nor possible.

Understanding band alignments in semiconductor heterostructures: Composition dependence and type-I-type-II transition of natural band offsets in nonpolar zinc-blende AlxGa1 -xN /AlyGa1 -yN composites

NASA Astrophysics Data System (ADS)

Landmann, M.; Rauls, E.; Schmidt, W. G.

2017-04-01

The composition dependence of the natural band alignment at nonpolar AlxGa1 -xN /AlyGa1 -yN heterojunctions is investigated via hybrid functional based density functional theory. Accurate band-gap data are provided using Heyd-Scuseria-Ernzerhof (HSE) type hybrid functionals with a composition dependent exact-exchange contribution. The unstrained band alignment between zincblende (zb) AlxGa1 -xN semiconductor alloys is studied within the entire ternary composition range utilizing the Branch-point technique to align the energy levels related to the bulklike direct Γv→Γc and indirect, pseudodirect, respectively, Γv→Xc type transitions in zb-AlxGa1 -xN . While the zb-GaN/AlxGa1 -xN band edges consistently show a type-I alignment, the relative position of fundamental band edges changes to a type-II alignment in the Al-rich composition ranges of zb-AlxGa1 -xN /AlN and zb-AlxGa1 -xN /AlyGa1 -yN systems. The presence of a direct-indirect band-gap transition at xc=0.63 in zb-AlxGa1 -xN semiconductor alloys gives rise to a notably different composition dependence of band discontinuities in the direct and indirect energy-gap ranges. Below the critical direct-indirect Al/Ga-crossover concentration, the band offsets show a close to linear dependence on the alloy composition. In contrast, notable bowing characteristics of all band discontinuities are observed above the critical crossover composition.

Analysis of opioid efficacy, tolerance, addiction and dependence from cell culture to human.

PubMed

Morgan, Michael M; Christie, MacDonald J

2011-10-01

Opioid agonists are the most effective treatment for pain, but their use is limited by side effects, tolerance and fears of addiction and dependence. A major goal of opioid research is to develop agonists that have high analgesic efficacy and a low profile for side effects, tolerance, addiction and dependence. Unfortunately, there is a serious lack of experimental data comparing the degree to which different opioids produce these effects in humans. In contrast, a wide range of experimental techniques from heterologous expression systems to behaviour assessment in whole animals have been developed to study these problems. The objective of this review is to describe and evaluate these techniques as they are used to study opioid efficacy, tolerance, addiction and dependence. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

Temperature dependence of exchange bias in (NiFe/IrMn)n multilayer films studied through static and dynamic techniques

NASA Astrophysics Data System (ADS)

Adams, Daniel J.; Khanal, Shankar; Khan, Mohammad Asif; Maksymov, Artur; Spinu, Leonard

2018-05-01

The in-plane temperature dependence of exchange bias was studied through both dc magnetometry and ferromagnetic resonance spectroscopy in a series of [NiFe/IrMn]n multilayer films, where n is the number of layer repetitions. Major hysteresis loops were recorded in the temperature range of 300 K to 2 K to reveal the effect of temperature on the exchange bias in the static regime while temperature-dependent continuous-wave ferromagnetic resonance for frequencies from 3 to 16 GHz was used to determine the exchange bias dynamically. Strong divergence between the values of exchange bias determined using the two different types of measurements as well as a peak in temperature dependence of the resonance linewidth were observed. These results are explained in terms of the slow-relaxer mechanism.

On the wrong inference of long-range correlations in climate data; the case of the solar and volcanic forcing over the Tropical Pacific

NASA Astrophysics Data System (ADS)

Varotsos, Costas A.; Efstathiou, Maria N.

2017-05-01

A substantial weakness of several climate studies on long-range dependence is the conclusion of long-term memory of the climate conditions, without considering it necessary to establish the power-law scaling and to reject a simple exponential decay of the autocorrelation function. We herewith show one paradigmatic case, where a strong long-range dependence could be wrongly inferred from incomplete data analysis. We firstly apply the DFA method on the solar and volcanic forcing time series over the tropical Pacific, during the past 1000 years and the results obtained show that a statistically significant straight line fit to the fluctuation function in a log-log representation is revealed with slope higher than 0.5, which wrongly may be assumed as an indication of persistent long-range correlations in the time series. We argue that the long-range dependence cannot be concluded just from this straight line fit, but it requires the fulfilment of the two additional prerequisites i.e. reject the exponential decay of the autocorrelation function and establish the power-law scaling. In fact, the investigation of the validity of these prerequisites showed that the DFA exponent higher than 0.5 does not justify the existence of persistent long-range correlations in the temporal evolution of the solar and volcanic forcing during last millennium. In other words, we show that empirical analyses, based on these two prerequisites must not be considered as panacea for a direct proof of scaling, but only as evidence that the scaling hypothesis is plausible. We also discuss the scaling behaviour of solar and volcanic forcing data based on the Haar tool, which recently proved its ability to reliably detect the existence of the scaling effect in climate series.

Including long-range dependence in integrate-and-fire models of the high interspike-interval variability of cortical neurons.

PubMed

Jackson, B Scott

2004-10-01

Many different types of integrate-and-fire models have been designed in order to explain how it is possible for a cortical neuron to integrate over many independent inputs while still producing highly variable spike trains. Within this context, the variability of spike trains has been almost exclusively measured using the coefficient of variation of interspike intervals. However, another important statistical property that has been found in cortical spike trains and is closely associated with their high firing variability is long-range dependence. We investigate the conditions, if any, under which such models produce output spike trains with both interspike-interval variability and long-range dependence similar to those that have previously been measured from actual cortical neurons. We first show analytically that a large class of high-variability integrate-and-fire models is incapable of producing such outputs based on the fact that their output spike trains are always mathematically equivalent to renewal processes. This class of models subsumes a majority of previously published models, including those that use excitation-inhibition balance, correlated inputs, partial reset, or nonlinear leakage to produce outputs with high variability. Next, we study integrate-and-fire models that have (nonPoissonian) renewal point process inputs instead of the Poisson point process inputs used in the preceding class of models. The confluence of our analytical and simulation results implies that the renewal-input model is capable of producing high variability and long-range dependence comparable to that seen in spike trains recorded from cortical neurons, but only if the interspike intervals of the inputs have infinite variance, a physiologically unrealistic condition. Finally, we suggest a new integrate-and-fire model that does not suffer any of the previously mentioned shortcomings. By analyzing simulation results for this model, we show that it is capable of producing output spike trains with interspike-interval variability and long-range dependence that match empirical data from cortical spike trains. This model is similar to the other models in this study, except that its inputs are fractional-gaussian-noise-driven Poisson processes rather than renewal point processes. In addition to this model's success in producing realistic output spike trains, its inputs have long-range dependence similar to that found in most subcortical neurons in sensory pathways, including the inputs to cortex. Analysis of output spike trains from simulations of this model also shows that a tight balance between the amounts of excitation and inhibition at the inputs to cortical neurons is not necessary for high interspike-interval variability at their outputs. Furthermore, in our analysis of this model, we show that the superposition of many fractional-gaussian-noise-driven Poisson processes does not approximate a Poisson process, which challenges the common assumption that the total effect of a large number of inputs on a neuron is well represented by a Poisson process.

Condition-dependent sex: who does it, when and why?

PubMed

Ram, Yoav; Hadany, Lilach

2016-10-19

We review the phenomenon of condition-dependent sex-where individuals' condition affects the likelihood that they will reproduce sexually rather than asexually. In recent years, condition-dependent sex has been studied both theoretically and empirically. Empirical results in microbes, fungi and plants support the theoretical prediction that negative condition-dependent sex, in which individuals in poor condition are more likely to reproduce sexually, can be evolutionarily advantageous under a wide range of settings. Here, we review the evidence for condition-dependent sex and its potential implications for the long-term survival and adaptability of populations. We conclude by asking why condition-dependent sex is not more commonly observed, and by considering generalizations of condition-dependent sex that might apply even for obligate sexuals.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'. © 2016 The Author(s).

Predictors of social anxiety in an opioid dependent sample and a control sample.

PubMed

Shand, Fiona L; Degenhardt, Louisa; Nelson, Elliot C; Mattick, Richard P

2010-01-01

Compared to other mental health problems, social anxiety is under-acknowledged amongst opioid dependent populations. This study aimed to assess levels of social anxiety and identify its predictors in an opioid dependent sample and a matched control group. Opioid dependent participants (n=1385) and controls (n=417) completed the Social Interaction Anxiety Scale (SIAS), the Social Phobia Scale (SPS) and a diagnostic interview. Regression analyses were used to test a range of predictors of social anxiety. Opioid dependent cases had higher mean scores on both scales compared to controls. Predictors of social anxiety centred on emotional rejection in childhood, either by parents or peers. For opioid dependent cases, but not controls, lifetime non-opioid substance dependence (cannabis, sedatives, and tobacco) was associated with higher levels of social anxiety. However, much of the variance in social anxiety remains unexplained for this population.

Predictors of social anxiety in an opioid dependent sample and a control sample

PubMed Central

Shand, Fiona L.; Degenhardt, Louisa; Nelson, Elliot C.; Mattick, Richard P.

2010-01-01

Compared to other mental health problems, social anxiety is under-acknowledged amongst opioid dependent populations. This study aimed to assess levels of social anxiety and identify its predictors in an opioid dependent sample and a matched control group. Opioid dependent participants (n = 1385) and controls (n = 417) completed the Social Interaction Anxiety Scale (SIAS), the Social Phobia Scale (SPS) and a diagnostic interview. Regression analyses were used to test a range of predictors of social anxiety. Opioid dependent cases had higher mean scores on both scales compared to controls. Predictors of social anxiety centred on emotional rejection in childhood, either by parents or peers. For opioid dependent cases, but not controls, lifetime non-opioid substance dependence (cannabis, sedatives, and tobacco) was associated with higher levels of social anxiety. However, much of the variance in social anxiety remains unexplained for this population. PMID:19775865

The elevation, slope, and curvature spectra of a wind roughened sea surface

NASA Technical Reports Server (NTRS)

Pierson, W. J., Jr.; Stacy, R. A.

1973-01-01

The elevation, slope and curvature spectra are defined as a function of wave number and depend on the friction velocity. There are five wave number ranges of definition called the gravity wave-gravity equilibrium range, the isotropic turbulence range, the connecting range due to Leykin Rosenberg, the capillary range, and the viscous cutoff range. The higher wave number ranges are strongly wind speed dependent, and there is no equilibrium (or saturated) capillary range, at least for winds up to 30 meters/sec. Some properties of the angular variation of the spectra are also found. For high wave numbers, especially in the capillary range, the results are shown to be consistent with the Rayleigh-Rice backscattering theory (Bragg scattering), and certain properties of the angular variation are deduced from backscatter measurements.

Simulation of the Burridge-Knopoff model of earthquakes with variable range stress transfer.

PubMed

Xia, Junchao; Gould, Harvey; Klein, W; Rundle, J B

2005-12-09

Simple models of earthquake faults are important for understanding the mechanisms for their observed behavior, such as Gutenberg-Richter scaling and the relation between large and small events, which is the basis for various forecasting methods. Although cellular automaton models have been studied extensively in the long-range stress transfer limit, this limit has not been studied for the Burridge-Knopoff model, which includes more realistic friction forces and inertia. We find that the latter model with long-range stress transfer exhibits qualitatively different behavior than both the long-range cellular automaton models and the usual Burridge-Knopoff model with nearest-neighbor springs, depending on the nature of the velocity-weakening friction force. These results have important implications for our understanding of earthquakes and other driven dissipative systems.

Analyzing the Coordinated Gene Network Underlying Temperature-Dependent Sex Determination in Reptiles

PubMed Central

Shoemaker, Christina M.; Crews, David

2009-01-01

Although gonadogenesis has been extensively studied in vertebrates with genetic sex determination, investigations at the molecular level in nontraditional model organisms with temperature-dependent sex determination are a relatively new area of research. Results show that while the key players of the molecular network underlying gonad development appear to be retained, their functions range from conserved to novel roles. In this review, we summarize experiments investigating candidate molecular players underlying temperature-dependent sex determination. We discuss some of the problems encountered unraveling this network, pose potential solutions, and suggest rewarding future directions of research. PMID:19022389

Frequency dependence of coherently amplified two-photon emission from hydrogen molecules

NASA Astrophysics Data System (ADS)

Hara, Hideaki; Miyamoto, Yuki; Hiraki, Takahiro; Masuda, Takahiko; Sasao, Noboru; Uetake, Satoshi; Yoshimi, Akihiro; Yoshimura, Koji; Yoshimura, Motohiko

2017-12-01

We investigate how the efficiency of coherently amplified two-photon emission depends on the frequency of one of the two emitted photons, namely the signal photon. This is done over the wavelength range of 5.048-10.21 μ m by using the vibrational transition of parahydrogen. The efficiency increases with the frequency of the signal photon. Considering experimental errors, our results are consistent with the theoretical prediction for the present experimental conditions. This study is an experimental demonstration of the frequency dependence of coherently amplified two-photon emission, and also presents its potential as a light source.

The juggling act: Do student nurses who care for dependants need an adapted course? An applied policy research study.

PubMed

Kiernan, Matthew D; Proud, Carole; Jackson, Sue

2015-11-01

In line with many countries worldwide, the Department of Health mandate to Health Education England seeks to promote the diversity of applicants by widening participation in nurse education. A number of studies have explored the experience of non-traditional students undertaking nursing courses. This study aimed to explore and understand the experiences of student nurses undertaking their nurse education whilst caring for dependant family. The study used an applied qualitative research approached based on methods developed for applied social policy research. The study was undertaken in an institution of higher education in the North East of England. The study population consisted of a convenience sample of 14 respondents, 13 female and 1 male. Ten respondents lived with partners and 3 had disabled dependants within the family. The age range of dependent children ranged from 3months to 19years. Data was collected through focus groups and telephone interviews using a semi-structured interview schedule. Framework analysis was used to analyse the data. Three superordinate themes were identified, Altruism and Commitment, Maturity and Family and Social Mobility, that best encapsulate the characteristics that enable this group to function well and complete their nurse education. Analysis identified a highly motivated group of students who's individual accounts showed that their lives, whilst in nurse education, were a constant series of compromises and 'juggling' between the demands of the course and the demands of their families. This group of students do not need an adapted course, but instead wish for a realistic nursing course where expectations are managed in an honest way. Basic common sense and good management of nursing courses will help ensure that this motivated group of people achieve their goals with minimum hardship or difficulties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Inhibition of DNA-Dependent Protein Kinase Activity for Breast Cancer Therapy

DTIC Science & Technology

2002-06-01

Dependent Protein Kinase Activity for Breast Cancer Therapy PRINCIPAL INVESTIGATOR: Chin-Rang Yang, Ph.D. CONTRACTING ORGANIZATION: University of Rochester...Activity for Breast Cancer Therapy 6. AUTHOR(S) Chin-Rang Yang, Ph.D. 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT...The formation of DNA double strand breaks (DSBs) correlates well with lethality of cancer cells following ionizing radiation (IR). The DNA-dependent

Structural, optical and dielectric properties of graphene oxide

NASA Astrophysics Data System (ADS)

Bhargava, Richa; Khan, Shakeel

2018-05-01

The Modified Hummers method has been used to synthesize Graphene oxide nanoparticles. Microstructural analyses were carried out by X-ray diffraction and Fourier transform infrared spectroscopy. Optical properties were studied by UV-visible spectroscopy in the range of 200-700 nm. The energy band gap was calculated with the help of Tauc relation. The frequency dependence of dielectric constant and dielectric loss were studied over a range of the frequency 75Hz to 5MHz at room temperature. The dispersion in dielectric constant can be explained with the help of Maxwell-Wagner model in studied nanoparticles.

Erroneous Arrhenius: Modified Arrhenius model best explains the temperature dependence of ectotherm fitness

PubMed Central

Knies, Jennifer L.; Kingsolver, Joel G.

2013-01-01

The initial rise of fitness that occurs with increasing temperature is attributed to Arrhenius kinetics, in which rates of reaction increase exponentially with increasing temperature. Models based on Arrhenius typically assume single rate-limiting reaction(s) over some physiological temperature range for which all the rate-limiting enzymes are in 100% active conformation. We test this assumption using datasets for microbes that have measurements of fitness (intrinsic rate of population growth) at many temperatures and over a broad temperature range, and for diverse ectotherms that have measurements at fewer temperatures. When measurements are available at many temperatures, strictly Arrhenius kinetics is rejected over the physiological temperature range. However, over a narrower temperature range, we cannot reject strictly Arrhenius kinetics. The temperature range also affects estimates of the temperature dependence of fitness. These results indicate that Arrhenius kinetics only apply over a narrow range of temperatures for ectotherms, complicating attempts to identify general patterns of temperature dependence. PMID:20528477

Erroneous Arrhenius: modified arrhenius model best explains the temperature dependence of ectotherm fitness.

PubMed

Knies, Jennifer L; Kingsolver, Joel G

2010-08-01

The initial rise of fitness that occurs with increasing temperature is attributed to Arrhenius kinetics, in which rates of reaction increase exponentially with increasing temperature. Models based on Arrhenius typically assume single rate-limiting reactions over some physiological temperature range for which all the rate-limiting enzymes are in 100% active conformation. We test this assumption using data sets for microbes that have measurements of fitness (intrinsic rate of population growth) at many temperatures and over a broad temperature range and for diverse ectotherms that have measurements at fewer temperatures. When measurements are available at many temperatures, strictly Arrhenius kinetics are rejected over the physiological temperature range. However, over a narrower temperature range, we cannot reject strictly Arrhenius kinetics. The temperature range also affects estimates of the temperature dependence of fitness. These results indicate that Arrhenius kinetics only apply over a narrow range of temperatures for ectotherms, complicating attempts to identify general patterns of temperature dependence.

An enhanced rheometer inertia correction procedure (ERIC) for the study of gelling systems using combined motor-transducer rheometers

NASA Astrophysics Data System (ADS)

Hudson, R. E.; Holder, A. J.; Hawkins, K. M.; Williams, P. R.; Curtis, D. J.

2017-12-01

The rheological characterisation of viscoelastic materials undergoing a sol-gel transition at the Gel Point (GP) has important applications in a wide range of industrial, biological, and clinical environments and can provide information regarding both kinetic and microstructural aspects of gelation. The most rigorous basis for identifying the GP involves exploiting the frequency dependence of the real and imaginary parts of the complex shear modulus of the critical gel (the system at the GP) measured under small amplitude oscillatory shear conditions. This approach to GP identification requires that rheological data be obtained over a range of oscillatory shear frequencies. Such measurements are limited by sample mutation considerations (at low frequencies) and, when experiments are conducted using combined motor-transducer (CMT) rheometers, by instrument inertia considerations (at high frequencies). Together, sample mutation and inertia induced artefacts can lead to significant errors in the determination of the GP. Overcoming such artefacts is important, however, as the extension of the range of frequencies available to the experimentalist promises both more accurate GP determination and the ability to study rapidly gelling samples. Herein, we exploit the frequency independent viscoelastic properties of the critical gel to develop and evaluate an enhanced rheometer inertia correction procedure. The procedure allows acquisition of valid GP data at previously inaccessible frequencies (using CMT rheometers) and is applied in a study of the concentration dependence of bovine gelatin gelation GP parameters. A previously unreported concentration dependence of the stress relaxation exponent (α) for critical gelatin gels has been identified, which approaches a limiting value (α = 0.7) at low gelatin concentrations, this being in agreement with previous studies and theoretical predictions for percolating systems at the GP.

Resveratrol Exerts Dosage and Duration Dependent Effect on Human Mesenchymal Stem Cell Development

PubMed Central

Peltz, Lindsay; Gomez, Jessica; Marquez, Maribel; Alencastro, Frances; Atashpanjeh, Negar; Quang, Tara; Bach, Thuy; Zhao, Yuanxiang

2012-01-01

Studies in the past have illuminated the potential benefit of resveratrol as an anticancer (pro-apoptosis) and life-extending (pro-survival) compound. However, these two different effects were observed at different concentration ranges. Studies of resveratrol in a wide range of concentrations on the same cell type are lacking, which is necessary to comprehend its diverse and sometimes contradictory cellular effects. In this study, we examined the effects of resveratrol on cell self-renewal and differentiation of human mesenchymal stem cells (hMSCs), a type of adult stem cells that reside in a number of tissues, at concentrations ranging from 0.1 to 10 µM after both short- and long-term exposure. Our results reveal that at 0.1 µM, resveratrol promotes cell self-renewal by inhibiting cellular senescence, whereas at 5 µM or above, resveratrol inhibits cell self-renewal by increasing senescence rate, cell doubling time and S-phase cell cycle arrest. At 1 µM, its effect on cell self-renewal is minimal but after long-term exposure it exerts an inhibitory effect, accompanied with increased senescence rate. At all concentrations, resveratrol promotes osteogenic differentiation in a dosage dependent manner, which is offset by its inhibitory effect on cell self-renewal at high concentrations. On the contrary, resveratrol suppresses adipogenic differentiation during short-term exposure but promotes this process after long-term exposure. Our study implicates that resveratrol is the most beneficial to stem cell development at 0.1 µM and caution should be taken in applying resveratrol as an anticancer therapeutic agent or nutraceutical supplement due to its dosage dependent effect on hMSCs. PMID:22615926

Tri-city study of Ecstasy use problems: a latent class analysis.

PubMed

Scheier, Lawrence M; Ben Abdallah, Arbi; Inciardi, James A; Copeland, Jan; Cottler, Linda B

2008-12-01

This study used latent class analysis to examine distinctive subtypes of Ecstasy users based on 24 abuse and dependence symptoms underlying standard DSM-IV criteria. Data came from a three site, population-based, epidemiological study to examine diagnostic nosology for Ecstasy use. Subject inclusion criteria included lifetime Ecstasy use exceeding five times and once in the past year, with participants ranging in age between 16 and 47 years of age from St. Louis, Miami, U.S. and Sydney, Australia. A satisfactory model typified four latent classes representing clearly differentiated diagnostic clusters including: (1) a group of sub-threshold users endorsing few abuse and dependence symptoms (negatives), (2) a group of 'diagnostic orphans' who had characteristic features of dependence for a select group of symptoms (mild dependent), (3) a 'transitional group' mimicking the orphans with regard to their profile of dependence also but reporting some abuse symptoms (moderate dependent), and (4) a 'severe dependent' group with a distinct profile of abuse and dependence symptoms. A multinomial logistic regression model indicated that certain latent classes showed unique associations with external non-diagnostic markers. Controlling for demographic characteristics and lifetime quantity of Ecstasy pill use, criminal behavior and motivational cues for Ecstasy use were the most efficient predictors of cluster membership. This study reinforces the heuristic utility of DSM-IV criteria applied to Ecstasy but with a different collage of symptoms that produced four distinct classes of Ecstasy users.

SU-F-T-322: A Comparison of Two Si Detectors for in Vivo Dosimetry

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

Talarico, O; Krylova, T; Lebedenko, I

Purpose: To compare two types of semiconductor detectors for in vivo dosimetry by their dependence from various parameters in different conditions. Methods: QED yellow (Sun Nuclear) and EDP (Scanditronix) Si detectors were radiated by a Varian Clinac 2300 ix with 6 and 18 MV energies. 10 cm thickness water equivalent phantom consisted of 30×30 cm{sup 2} squared plates was used for experiments. Dose dependencies for different beam angles (0 – 180°), field size (3–40 cm), dose (50 – 300 MU), and dose rates (50 – 300 MU/min) were obtained and calibrated with Standard Farmer chamber (PTW). Results: Reproducibility, linearity, dosemore » rate, angular dependence, and field size dependence were obtained for QED and EDP. They show no dose-rate dependence in available clinical dose rate range (100–600 MU/min). Both diodes have linear dependence with increasing the dose. Therefore even in case of high radiation therapy (including total body irradiation) it is not necessary to apply an additional correction during in vivo dosimetry. The diodes have different behavior for angular and field size dependencies. QED diode showed that dose value is stable for beam angles from 0 to 60°, for 60–180° correction factor has to be applied for each beam angle during in vivo measurements. For EDP diode dose value is sensitive to beam angle in whole range of angles. Conclusion: The study shows that QED diode is more suitable for in vivo dosimetry due to dose value independence from incident beam angle in the range 0–60°. There is no need in correction factors for increasing of dose and dose rate for both diodes. The next step will be to carry out measurements in non-standard conditions of total body irradiation. After this modeling of these experiments with Monte Carlo simulation for comparison calculated and obtained data is planned.« less

A Monte Carlo study of the quality dependence factors of common TLD materials in photon and electron beams.

PubMed

Mobit, P N; Nahum, A E; Mayles, P

1998-08-01

A Monte Carlo simulation of the quality dependence of different TL materials, in the form of discs 3.61 mm in diameter and 0.9 mm thick, in radiotherapy photon beams relative to 60Co gamma-rays has been performed. The beam qualities ranged from 50 kV to 25 MV x-rays. The TL materials were: CaF2, CaSO4, LiF and Li2B4O7. The effects of the dopants on energy deposition in the TL material have also been determined for the highly sensitive LiF:Mg:Cu:P (TLD-100H) and for CaF2:Mn. It was found that there was a significant difference in the quality dependence factor derived from Monte Carlo simulations between LiF and LiF:Mg:Cu:P but not between CaF2 and CaF2:Mn. The quality dependence factors for Li2B4O7 varied from 0.990 +/- 0.008 (1 sd) for 25 MV x-rays to 0.940 +/- 0.009 (1 sd) for 50 kV x-rays relative to 60Co gamma-rays; Monte Carlo simulations were also performed for Li2B4O7 in megavoltage electron beams. For CaF2, the quality dependence factor varied from 0.927 +/- 0.008 (1 sd) for 25 MV x-rays to 10.561 +/- 0.008 (1 sd) for 50 kV x-rays. The figure for CaSO4 ranged from 0.943 +/- 0.008 (1 sd) for 25 MV x-rays to 9.010 +/- 0.008 (1 sd) for 50 kV x-rays. The quality dependence factor for CaF2 increases by up to 5% with depth and by up to 15% with field size for the kilovoltage x-ray beams. For LiF-TLD, however, there was no significant dependence on the field size or depth of irradiation in the kilovoltage energy range.

Methods, computer readable media, and graphical user interfaces for analysis of frequency selective surfaces

DOEpatents

Kotter, Dale K [Shelley, ID; Rohrbaugh, David T [Idaho Falls, ID

2010-09-07

A frequency selective surface (FSS) and associated methods for modeling, analyzing and designing the FSS are disclosed. The FSS includes a pattern of conductive material formed on a substrate to form an array of resonance elements. At least one aspect of the frequency selective surface is determined by defining a frequency range including multiple frequency values, determining a frequency dependent permittivity across the frequency range for the substrate, determining a frequency dependent conductivity across the frequency range for the conductive material, and analyzing the frequency selective surface using a method of moments analysis at each of the multiple frequency values for an incident electromagnetic energy impinging on the frequency selective surface. The frequency dependent permittivity and the frequency dependent conductivity are included in the method of moments analysis.

Short-term outcomes of mothers and newborn infants with comorbid psychiatric disorders and drug dependency.

PubMed

Oei, Ju Lee; Abdel-Latif, Mohamed E; Craig, Fiona; Kee, Aivy; Austin, Marie-Paule; Lui, Kei

2009-04-01

The aim of the present study was to determine the characteristics and short-term outcomes of mother-infant pairs with comorbid drug dependency and psychiatric disorders. A population-based retrospective chart review was carried out of 879 drug-dependent mother and infant pairs in New South Wales (NSW) and the Australian Capital Territory (ACT) who delivered between 1 January and 31 December 2004. Psychiatric comorbidity (dual diagnosis, DD) was identified in 396 (45%) of the 879 drug-dependent women. DSM-IV depression (79%), followed by anxiety (20%), was most prevalent. DD women were more likely to use amphetamines (29% vs 18%, p < 0.05), less likely to use opiates (42% vs 51%, p < 0.05) and to have had no antenatal care (24% vs 8%, p < 0.05). They also had more previous pregnancies (4, range = 2-5 vs 3, range = 2-5, p < 0.05) and domestic violence (29% vs 14%, p < 0.05) was more common. DD infants were less likely to be admitted to a nursery (47% vs 55%, p < 0.05). Withdrawal scores were similar (maximum median Finnegan scores = 4 (interquartile range = 3-8) vs 10 (interquartile range = 7-12, p = 0.30) but fewer needed withdrawal medication (19% vs 27%, p < 0.05). Maternal psychotropic agents did not worsen the severity of neonatal withdrawal. Psychiatric comorbidity, especially depression, is common and affects almost half of drug-using mothers. Antenatal care, drug use and social outcomes are worse for DD mothers and their infants. It is recommended that all drug-using women be assessed antenatally for psychosocial disorders so that timely mental health intervention can be offered, if required.

Viability of long range dragonfly migration across the Indian Ocean: An energetics perspective

NASA Astrophysics Data System (ADS)

Saha, Sandeep; Nirwal, Satvik

2016-11-01

Recently Pantala flavescens (dragonflies) have been reported to migrate in millions from India to Eastern Africa on a multigenerational migratory circuit of length 14000-18000 kms. We attempt to understand the ability of dragonflies to perform long range migration by examining the energetics using computer simulations. In absence of a theory for long range insect migrations, we resort to the extensive literature on long range bird migration from the energetics perspective. The flight energetics depends upon instantaneous power and velocity. The mechanical flight power is computed from the power curve which is then converted to mass depletion using Brequet's equation. However, the mechanical flight power itself depends upon the instantaneous velocity which can vary depending upon the current mass. In order to predict the range in our simulations, we assume that the insect progressively tries to achieve the maximum range velocity. The results indicate that the migration range is approximately 1260 kms in 70 hours based on the true airspeed. However, our analysis is restricted by the lack of data and certain caveats in drag prediction and basal metabolism rate.

Is Relational Reasoning Dependent on Language? A Voxel-Based Lesion Symptom Mapping Study

ERIC Educational Resources Information Center

Baldo, Juliana V.; Bunge, Silvia A.; Wilson, Stephen M.; Dronkers, Nina F.

2010-01-01

Previous studies with brain-injured patients have suggested that language abilities are necessary for complex problem-solving, even when tasks are non-verbal. In the current study, we tested this notion by analyzing behavioral and neuroimaging data from a large group of left-hemisphere stroke patients (n = 107) suffering from a range of language…

[Pregnancy and substance use in France: a literature review].

PubMed

Dumas, A; Simmat-Durand, L; Lejeune, C

2014-11-01

Substance use during pregnancy is an important public health issue. It requires identifying at-risk populations and risk perception among women. A literature review was conducted. It included French studies conducted since 2000 on substance use during pregnancy (tobacco, alcohol, marijuana, psychotropic drugs) and risk perception. In France, in 2010, 24% of pregnant women smoke--17% in the 3rd trimester. Depending on studies, the prevalence of alcohol use ranged from 12 to 63% and binge drinking ranged from 1 to 7%; daily drinking was below 0.5%. Marijuana use ranged from 1 to 3%, and psychotropic drugs ranged from 2 to 4%. Little research has been dedicated to risk perception. Studies show a lack of awareness about the equivalence of risks between fermented and distilled beverages and about the risks of moderate smoking during pregnancy. Data is lacking to characterize at-risk populations and mechanisms underlying risky behaviors. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

The Return of Rate Dependence.

PubMed

Quisenberry, Amanda J; Snider, Sarah E; Bickel, Warren K

2016-11-01

Rate dependence, a well-known phenomenon in behavioral pharmacology, appears to have declined as a topic of interest, perhaps, as a result of being viewed pertinent to only the preclinical investigation of drugs on schedule-controlled performance. Obstacles to data interpretation due to conflation with regression to the mean also appear to have contributed to the topic's decline. Despite this reduction in exposure, rate dependence is a useful concept and tool that can be used to determine sources of variability, predict therapeutic outcomes, and identify individuals that are most likely to respond therapeutically. Armed with new statistical methods and an understanding of the broad range of conditions under which rate dependence can be observed, we urge researchers to revisit the concept, use the appropriate analysis methods, and to design empirical studies a priori to further explore rate dependence.

Finger Interdependence: Linking the Kinetic and Kinematic Variables

PubMed Central

Kim, Sun Wook; Shim, Jae Kun; Zatsiorsky, Vladimir M.; Latash, Mark L.

2008-01-01

We studied the dependence between voluntary motion of a finger and pressing forces produced by the tips of other fingers of the hand. Subjects moved one of the fingers (task finger) of the right hand trying to follow a cyclic, ramp-like flexion-extension template at different frequencies. The other fingers (slave fingers) were restricted from moving; their flexion forces were recorded and analyzed. Index finger motion caused the smallest force production by the slave fingers. Larger forces were produced by the neighbors of the task finger; these forces showed strong modulation over the range of motion of the task finger. The enslaved forces were higher during the flexion phase of the movement cycle as compared to the extension phase. The index of enslaving expressed in N/rad was higher when the task finger moved through the more flexed postures. The dependence of enslaving on both range and direction of task finger motion poses problems for methods of analysis of finger coordination based on an assumption of universal matrices of finger inter-dependence. PMID:18255182

Shape dependent electronic structure and exciton dynamics in small In(Ga)As quantum dots

NASA Astrophysics Data System (ADS)

Gomis, J.; Martínez-Pastor, J.; Alén, B.; Granados, D.; García, J. M.; Roussignol, P.

2006-12-01

We present a study of the primary optical transitions and recombination dynamics in InGaAs self-assembled quantum nanostructures with different shape. Starting from the same quantum dot seeding layer, and depending on the overgrowth conditions, these new nanostructures can be tailored in shape and are characterized by heights lower than 2 nm and base lengths around 100 nm. The geometrical shape strongly influences the electronic and optical properties of these nanostructuctures. We measure for them ground state optical transitions in the range 1.25 1.35 eV and varying energy splitting between their excited states. The temperature dependence of the exciton recombination dynamics is reported focusing on the intermediate temperature regime (before thermal escape begins to be important). In this range, an important increase of the effective photoluminescence decay time is observed and attributed to the state filling and exciton thermalization between excited and ground states. A rate equation model is also developed reproducing quite well the observed exciton dynamics.

Diameter dependent thermoelectric properties of individual SnTe nanowires

DOE PAGES

Xu, E. Z.; Li, Z.; Martinez, J. A.; ...

2015-01-15

The lead-free compound tin telluride (SnTe) has recently been suggested to be a promising thermoelectric material. In this work, we report on the first thermoelectric study of individual single-crystalline SnTe nanowires with different diameters ranging from ~ 218 to ~ 913 nm. Measurements of thermopower S, electrical conductivity σ and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25 - 300 K. While the electrical conductivity does not show a strong diameter dependence, the thermopower increases by a factor of two when the nanowire diameter is decreased from ~ 913 nm to ~more » 218 nm. The thermal conductivity of the measured NWs is lower than that of the bulk SnTe, which may arise from the enhanced phonon - surface boundary scattering and phonon-defect scattering. Lastly, temperature dependent figure of merit ZT was determined for individual nanowires and the achieved maximum value at room temperature is about three times higher than that in bulk samples of comparable carrier density.« less

Distribution of Curcumin and THC in Peripheral Blood Mononuclear Cells Isolated from Healthy Individuals and Patients with Chronic Lymphocytic Leukemia.

PubMed

Bolger, Gordon T; Licollari, Albert; Tan, Aimin; Greil, Richard; Pleyer, Lisa; Vcelar, Brigitta; Majeed, Muhammad; Sordillo, Peter

2018-01-01

Background/Aim: Curcumin is being widely investigated for its anticancer properties and studies in the literature suggest that curcumin distributes to a higher degree in tumor versus non-tumor cells. In the current study, we report on investigation of the distribution of curcumin and metabolism to THC in PBMC from healthy individuals and chronic lymphocytic leukemia (CLL) patients following exposure to Lipocurc™ (liposomal curcumin). Materials and Methods: The time and temperature-dependent distribution of liposomal curcumin and metabolism to tetrahydrocurcumin (THC) were measured in vitro in human peripheral blood mononuclear cells (PBMC) obtained from healthy individuals, PBMC HI (cryopreserved and freshly isolated PBMC) and CLL patients (cryopreserved PBMC) with lymphocyte counts ranging from 17-58×10 6 cells/ml (PBMC CLL,Grp 1 ) and >150×10 6 cells/ml (PBMC CLL,Grp 2 ). PBMC were incubated in plasma protein supplemented media with Lipocurc™ for 2-16 min at 37°C and 4°C and the cell and medium levels of curcumin determined by LC-MS/MS. Results: PBMC from CLL patients displayed a 2.2-2.6-fold higher distribution of curcumin compared to PBMC HI Curcumin distribution into PBMCCLL, Grp 1/Grp 2 ranged from 384.75 - 574.50 ng/g w.w. of cell pellet and was greater compared to PBMC HI that ranged from 122.27-220.59 ng/g w.w. of cell pellet following incubation for up to 15-16 min at 37°C. The distribution of curcumin into PBMC CLL,Grp 2 was time-dependent in comparison to PBMC HI which did not display a time-dependence and there was no temperature-dependence for curcumin distribution in either cell type. Curcumin was metabolized to THC in PBMC. The metabolism of curcumin to THC was not markedly different between PBMC HI (range=23.94-42.04 ng/g w.w. cell pellet) and PBMC CLL,Grp 1/Grp 2 (range=23.08-48.22 ng/g. w.w. cell pellet). However, a significantly greater time and temperature-dependence was noted for THC in PBMC CLL,Grp 2 compared to PBMC HI Conclusion: Curcumin distribution into PBMC from CLL patients was higher compared to PBMC from healthy individuals, while metabolism to THC was similar. The potential for a greater distribution of curcumin into PBMC from CLL patients may be of therapeutic benefit. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Behaviour of phase functions of Olivine and Augite assemblages in the wavelength range 0.3-18 μm

NASA Astrophysics Data System (ADS)

Salgueiro da Silva, M. A.; Seixas, T. M.; Maturilli, A.; Helbert, J.

2017-09-01

We tested the validity of the wavelength-independent phase function assumption by measuring BDR of olivine and augite mineral assemblages in the extended spectral range 0.3-18 μm. Because quasi-isotropic scattering is present in both OL and AUG assemblages with grain-size dependent features, it is not clear that this is an intrinsic effect attributed to the wavelength dependence of the optical constants of olivine and augite minerals. Our results show that the application of Hapke model to olivine and augite BDR spectra in the MIR range requires a wavelength- and, possibly, grain size-dependent phase function.

Systematics of heavy-ion charge-exchange straggling

NASA Astrophysics Data System (ADS)

Sigmund, P.; Schinner, A.

2016-10-01

The dependence of heavy-ion charge-exchange straggling on the beam energy has been studied theoretically for several ion-target combinations. Our previous work addressed ions up to krypton, while the present study focuses on heavier ions, especially uranium. Particular attention has been paid to a multiple-peak structure which has been predicted theoretically in our previous work. For high-Z1 and high-Z2 systems, exemplified by U in Au, we identify three maxima in the energy dependence of charge-exchange straggling, while the overall magnitude is comparable with that of collisional straggling. Conversely, for U in C, charge-exchange straggling dominates, but only two peaks lie in the energy range where we presently are able to produce credible predictions. For U-Al we find good agreement with experiment in the energy range around the high-energy maximum. The position of the high-energy peak - which is related to processes in the projectile K shell - is found to scale as Z12, in contrast to the semi-empirical Z13/2 dependence proposed by Yang et al. Measurements for heavy ions in heavy targets are suggested in order to reconcile a major discrepancy between the present calculations and the frequently-used formula by Yang et al.

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

Quashie, Edwin E.; Saha, Bidhan C.; Correa, Alfredo A.

Here, we present an ab initio study of the electronic stopping power of protons in copper over a wide range of proton velocities v = 0.02–10a.u. where we take into account nonlinear effects. Time-dependent density functional theory coupled with molecular dynamics is used to study electronic excitations produced by energetic protons. A plane-wave pseudopotential scheme is employed to solve the time-dependent Kohn-Sham equations for a moving ion in a periodic crystal. The electronic excitations and the band structure determine the stopping power of the material and alter the interatomic forces for both channeling and off-channeling trajectories. Our off-channeling results aremore » in quantitative agreement with experiments, and at low velocity they unveil a crossover region of superlinear velocity dependence (with a power of ~1.5) in the velocity range v = 0.07–0.3a.u., which we associate to the copper crystalline electronic band structure. The results are rationalized by simple band models connecting two separate regimes. We find that the limit of electronic stopping v → 0 is not as simple as phenomenological models suggest and it is plagued by band-structure effects.« less

Range compensation for backscattering measurements in the difference-frequency nearfield of a parametric sonar.

PubMed

Foote, Kenneth G

2012-05-01

Measurement of acoustic backscattering properties of targets requires removal of the range dependence of echoes. This process is called range compensation. For conventional sonars making measurements in the transducer farfield, the compensation removes effects of geometrical spreading and absorption. For parametric sonars consisting of a parametric acoustic transmitter and a conventional-sonar receiver, two additional range dependences require compensation when making measurements in the nonlinearly generated difference-frequency nearfield: an apparently increasing source level and a changing beamwidth. General expressions are derived for range compensation functions in the difference-frequency nearfield of parametric sonars. These are evaluated numerically for a parametric sonar whose difference-frequency band, effectively 1-6 kHz, is being used to observe Atlantic herring (Clupea harengus) in situ. Range compensation functions for this sonar are compared with corresponding functions for conventional sonars for the cases of single and multiple scatterers. Dependences of these range compensation functions on the parametric sonar transducer shape, size, acoustic power density, and hydrography are investigated. Parametric range compensation functions, when applied with calibration data, will enable difference-frequency echoes to be expressed in physical units of volume backscattering, and backscattering spectra, including fish-swimbladder-resonances, to be analyzed.

Complex temperature dependence of coupling and dissipation of cavity magnon polaritons from millikelvin to room temperature

NASA Astrophysics Data System (ADS)

Boventer, Isabella; Pfirrmann, Marco; Krause, Julius; Schön, Yannick; Kläui, Mathias; Weides, Martin

2018-05-01

Hybridized magnonic-photonic systems are key components for future information processing technologies such as storage, manipulation, or conversion of data both in the classical (mostly at room temperature) and quantum (cryogenic) regime. In this work, we investigate a yttrium-iron-garnet sphere coupled strongly to a microwave cavity over the full temperature range from 290 K to 30 mK . The cavity-magnon polaritons are studied from the classical to the quantum regimes where the thermal energy is less than one resonant microwave quanta, i.e., at temperatures below 1 K . We compare the temperature dependence of the coupling strength geff(T ) , describing the strength of coherent energy exchange between spin ensemble and cavity photon, to the temperature behavior of the saturation magnetization evolution Ms(T ) and find strong deviations at low temperatures. The temperature dependence of magnonic disspation is governed at intermediate temperatures by rare-earth impurity scattering leading to a strong peak at 40 K . The linewidth κm decreases to 1.2 MHz at 30 mK , making this system suitable as a building block for quantum electrodynamics experiments. We achieve an electromagnonic cooperativity in excess of 20 over the entire temperature range, with values beyond 100 in the millikelvin regime as well as at room temperature. With our measurements, spectroscopy on strongly coupled magnon-photon systems is demonstrated as versatile tool for spin material studies over large temperature ranges. Key parameters are provided in a single measurement, thus simplifying investigations significantly.

Implicitly Defined Neural Networks for Sequence Labeling

DTIC Science & Technology

2017-07-31

network are coupled together, in order to improve perfor- mance on complex, long-range dependencies in either direction of a sequence. We contrast our...struc- ture. 1.1 Related Work Long-range dependencies have been an issue as long as there have been NLP tasks, and there are many ef- fective approaches...retain informa- tion about dependencies . The Bidirectional LSTM (b- LSTM) (Graves and Schmidhuber, 2005), a natural ex- tension of (Schuster and Paliwal

Ionic-to-electronic conductivity of glasses in the P2O5-V2O5-ZnO-Li2O system

NASA Astrophysics Data System (ADS)

Langar, A.; Sdiri, N.; Elhouichet, H.; Ferid, M.

2016-12-01

Glasses having a composition 15V2O5-5ZnO-(80- x P2O5- xLi2O ( x = 5 , 10, 15 mol%) were prepared by the conventional melt quenching. Conduction and relaxation mechanisms in these glasses were studied using impedance spectroscopy in a frequency range from 10 Hz to 10 MHz and in a temperature range from 513 K to 566 K. The structure of the amorphous synthetic product was corroborated by X-ray diffraction (disappearance of nacrite peaks). The DC conductivity follows the Arrhenius law and the activation energy determined by regression analysis varies with the content of Li2O. Frequency-dependent AC conductivity was analyzed by Jonscher's universal power law, which is varying as ωn, and the temperature-dependent power parameter supported by the Correlated Barrier Hopping (CBH) model. For x = 15 mol%, the values of n ≤ 0.5 confirm the dominance of ionic conductivity. The analysis of the modulus formalism with a distribution of relaxation times was carried out using the Kohlrausch-Williams-Watts (KWW) stretched exponential function. The stretching exponent, β, is dependent on temperature. The analysis of the temperature variation of the M" peak indicates that the relaxation process is thermally activated. Modulus study reveals the temperature-dependent non-Debye-type relaxation phenomenon.

On the Dependence of the Ionospheric E-Region Electric Field of the Solar Activity

NASA Astrophysics Data System (ADS)

Denardini, Clezio Marcos; Schuch, Nelson Jorge; Moro, Juliano; Araujo Resende, Laysa Cristina; Chen, Sony Su; Costa, D. Joaquim

2016-07-01

We have being studying the zonal and vertical E region electric field components inferred from the Doppler shifts of type 2 echoes (gradient drift irregularities) detected with the 50 MHz backscatter coherent (RESCO) radar set at Sao Luis, Brazil (SLZ, 2.3° S, 44.2° W) during the solar cycle 24. In this report we present the dependence of the vertical and zonal components of this electric field with the solar activity, based on the solar flux F10.7. For this study we consider the geomagnetically quiet days only (Kp <= 3+). A magnetic field-aligned-integrated conductivity model was developed for proving the conductivities, using the IRI-2007, the MISIS-2000 and the IGRF-11 models as input parameters for ionosphere, neutral atmosphere and Earth magnetic field, respectively. The ion-neutron collision frequencies of all the species are combined through the momentum transfer collision frequency equation. The mean zonal component of the electric field, which normally ranged from 0.19 to 0.35 mV/m between the 8 and 18 h (LT) in the Brazilian sector, show a small dependency with the solar activity. Whereas, the mean vertical component of the electric field, which normally ranges from 4.65 to 10.12 mV/m, highlight the more pronounced dependency of the solar flux.

Evolution of structural, electronic and magneto-transport properties of Sr2Ir1-xTixO4 5d based oxide

NASA Astrophysics Data System (ADS)

Bhatti, Imtiaz Noor; Pramanik, A. K.

2018-05-01

To investigate the effect of chemical doping on structural and transport properties in Sr2IrO4, in this study we have doped Ti4+ (3d0) at Ir4+ (5d5) site. Thus Ti doping introduces hole in the electronic band moreover, it also weaken the spin orbital coupling (SOC) and enhance electronic correlation (U). We have prepared the polycrystalline samples of Sr2Ir1-xTixO4 with x = 0.0 0.05 and 0.10 with solid state reaction method. Single phase and chemically pure samples were obtained. All samples crystalizes in tetragonal structure and I41/acd symmetry. The structural analysis shows the evolution of lattice parameter with doping. The temperature dependent resistivity is measured using four probe technique down in the temperature range 5 K-300 K. The resistivity increases with Ti doping. Temperature dependency of resistivity is explained by thermal activated 2-dimensional Mott Variable Hopping range model. To further understand the transport behavior both temperature and field dependent magneto-resistance is also studied. Negative magneto-resistance (MR) has been observed for all samples at 50 K. The MR shows quadratic field dependence at high field, implies a relevance of a quantum interference effect in this spin orbital coupled insulator.

Further results on open-loop compensation of rate-dependent hysteresis in a magnetostrictive actuator with the Prandtl-Ishlinskii model

NASA Astrophysics Data System (ADS)

Al Janaideh, Mohammad; Aljanaideh, Omar

2018-05-01

Apart from the output-input hysteresis loops, the magnetostrictive actuators also exhibit asymmetry and saturation, particularly under moderate to large magnitude inputs and at relatively higher frequencies. Such nonlinear input-output characteristics could be effectively characterized by a rate-dependent Prandtl-Ishlinskii model in conjunction with a function of deadband operators. In this study, an inverse model is formulated to seek real-time compensation of rate-dependent and asymmetric hysteresis nonlinearities of a Terfenol-D magnetostrictive actuator. The inverse model is formulated with the inverse of the rate-dependent Prandtl-Ishlinskii model, satisfying the threshold dilation condition, with the inverse of the deadband function. The inverse model was subsequently applied to the hysteresis model as a feedforward compensator. The proposed compensator is applied as a feedforward compensator to the actuator hardware to study its potential for rate-dependent and asymmetric hysteresis loops. The experimental results are obtained under harmonic and complex harmonic inputs further revealed that the inverse compensator can substantially suppress the hysteresis and output asymmetry nonlinearities in the entire frequency range considered in the study.

Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory.

PubMed

Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J; Lopata, Kenneth

2016-09-07

Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.

Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory

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

Sissay, Adonay; Abanador, Paul; Mauger, François

2016-09-07

Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagatingmore » the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.« less

Dependence of the atomic level Green-Kubo stress correlation function on wavevector and frequency: molecular dynamics results from a model liquid.

PubMed

Levashov, V A

2014-09-28

We report on a further investigation of a new method that can be used to address vibrational dynamics and propagation of stress waves in liquids. The method is based on the decomposition of the macroscopic Green-Kubo stress correlation function into the atomic level stress correlation functions. This decomposition, as was demonstrated previously for a model liquid studied in molecular dynamics simulations, reveals the presence of stress waves propagating over large distances and a structure that resembles the pair density function. In this paper, by performing the Fourier transforms of the atomic level stress correlation functions, we elucidate how the lifetimes of the stress waves and the ranges of their propagation depend on their frequency, wavevector, and temperature. These results relate frequency and wavevector dependence of the generalized viscosity to the character of propagation of the shear stress waves. In particular, the results suggest that an increase in the value of the frequency dependent viscosity at low frequencies with decrease of temperature is related to the increase in the ranges of propagation of the stress waves of the corresponding low frequencies. We found that the ranges of propagation of the shear stress waves of frequencies less than half of the Einstein frequency extend well beyond the nearest neighbor shell even above the melting temperature. The results also show that the crossover from quasilocalized to propagating behavior occurs at frequencies usually associated with the Boson peak.

Dose dependence of nano-hardness of 6H-SiC crystal under irradiation with inert gas ions

NASA Astrophysics Data System (ADS)

Yang, Yitao; Zhang, Chonghong; Su, Changhao; Ding, Zhaonan; Song, Yin

2018-05-01

Single crystal 6H-SiC was irradiated by inert gas ions (He, Ne, Kr and Xe ions) to various damage levels at room temperature. Nano-indentation test was performed to investigate the hardness change behavior with damage. The depth profile of nano-hardness for 6H-SiC decreased with increasing depth for both the pristine and irradiated samples, which was known as indentation size effect (ISE). Nix-Gao model was proposed to determine an asymptotic value of nano-hardness by taking account of ISE for both the pristine and irradiated samples. In this study, nano-hardness of the irradiated samples showed a strong dependence on damage level and showed a weak dependence on ions species. From the dependence of hardness on damage, it was found that the change of hardness demonstrated three distinguishable stages with damage: (I) The hardness increased with damage from 0 to 0.2 dpa and achieved a maximum of hardening fraction ∼20% at 0.2 dpa. The increase of hardness in this damage range was contributed to defects produced by ion irradiation, which can be described well by Taylor relation. (II) The hardness reduced rapidly with large decrement in the damage range from 0.2 to 0.5 dpa, which was considered to be from the covalent bond breaking. (III) The hardness reduced with small decrement in the damage range from 0.5 to 2.2 dpa, which was induced by extension of the amorphous layer around damage peak.

Explicating the Conditions Under Which Multilevel Multiple Imputation Mitigates Bias Resulting from Random Coefficient-Dependent Missing Longitudinal Data.

PubMed

Gottfredson, Nisha C; Sterba, Sonya K; Jackson, Kristina M

2017-01-01

Random coefficient-dependent (RCD) missingness is a non-ignorable mechanism through which missing data can arise in longitudinal designs. RCD, for which we cannot test, is a problematic form of missingness that occurs if subject-specific random effects correlate with propensity for missingness or dropout. Particularly when covariate missingness is a problem, investigators typically handle missing longitudinal data by using single-level multiple imputation procedures implemented with long-format data, which ignores within-person dependency entirely, or implemented with wide-format (i.e., multivariate) data, which ignores some aspects of within-person dependency. When either of these standard approaches to handling missing longitudinal data is used, RCD missingness leads to parameter bias and incorrect inference. We explain why multilevel multiple imputation (MMI) should alleviate bias induced by a RCD missing data mechanism under conditions that contribute to stronger determinacy of random coefficients. We evaluate our hypothesis with a simulation study. Three design factors are considered: intraclass correlation (ICC; ranging from .25 to .75), number of waves (ranging from 4 to 8), and percent of missing data (ranging from 20 to 50%). We find that MMI greatly outperforms the single-level wide-format (multivariate) method for imputation under a RCD mechanism. For the MMI analyses, bias was most alleviated when the ICC is high, there were more waves of data, and when there was less missing data. Practical recommendations for handling longitudinal missing data are suggested.

Evaluation of an empirical monitor output estimation in carbon ion radiotherapy.

PubMed

Matsumura, Akihiko; Yusa, Ken; Kanai, Tatsuaki; Mizota, Manabu; Ohno, Tatsuya; Nakano, Takashi

2015-09-01

A conventional broad beam method is applied to carbon ion radiotherapy at Gunma University Heavy Ion Medical Center. According to this method, accelerated carbon ions are scattered by various beam line devices to form 3D dose distribution. The physical dose per monitor unit (d/MU) at the isocenter, therefore, depends on beam line parameters and should be calibrated by a measurement in clinical practice. This study aims to develop a calculation algorithm for d/MU using beam line parameters. Two major factors, the range shifter dependence and the field aperture effect, are measured via PinPoint chamber in a water phantom, which is an identical setup as that used for monitor calibration in clinical practice. An empirical monitor calibration method based on measurement results is developed using a simple algorithm utilizing a linear function and a double Gaussian pencil beam distribution to express the range shifter dependence and the field aperture effect. The range shifter dependence and the field aperture effect are evaluated to have errors of 0.2% and 0.5%, respectively. The proposed method has successfully estimated d/MU with a difference of less than 1% with respect to the measurement results. Taking the measurement deviation of about 0.3% into account, this result is sufficiently accurate for clinical applications. An empirical procedure to estimate d/MU with a simple algorithm is established in this research. This procedure allows them to use the beam time for more treatments, quality assurances, and other research endeavors.

The Faraday effect of natural and artificial ferritins.

PubMed

Koralewski, M; Kłos, J W; Baranowski, M; Mitróová, Z; Kopčanský, P; Melníková, L; Okuda, M; Schwarzacher, W

2012-09-07

Measurements of the Faraday rotation at room temperature over the light wavelength range of 300-680 nm for horse spleen ferritin (HSF), magnetoferritin with different loading factors (LFs) and nanoscale magnetite and Fe(2)O(3) suspensions are reported. The Faraday rotation and the magnetization of the materials studied present similar magnetic field dependences and are characteristic of a superparamagnetic system. The dependence of the Faraday rotation on the magnetic field is described, excluding HSF and Fe(2)O(3), by a Langevin function with a log-normal distribution of the particle size allowing the core diameters of the substances studied to be calculated. It was found that the specific Verdet constant depends linearly on the LF. Differences in the Faraday rotation spectra and their magnetic field dependences allow discrimination between magnetoferritin with maghemite and magnetite cores which can be very useful in biomedicine.

Characteristics of Protons Exiting from a Polyethylene Converter Irradiated by Neutrons with Energies between 1 keV and 10 MeV.

PubMed

Nikezic, D; Shahmohammadi Beni, Mehrdad; Krstic, D; Yu, K N

2016-01-01

Monte Carlo method has been used to determine the efficiency for proton production and to study the energy and angular distributions of the generated protons. The ENDF library of cross sections is used to simulate the interactions between the neutrons and the atoms in a polyethylene (PE) layer, while the ranges of protons with different energies in PE are determined using the Stopping and Range of Ions in Matter (SRIM) computer code. The efficiency of proton production increases with the PE layer thickness. However the proton escaping from a certain polyethylene volume is highly dependent on the neutron energy and target thickness, except for a very thin PE layer. The energy and angular distributions of protons are also estimated in the present paper, showing that, for the range of energy and thickness considered, the proton flux escaping is dependent on the PE layer thickness, with the presence of an optimal thickness for a fixed primary neutron energy.

Equatorial plasma bubbles/range spread F irregularities and the QBO

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

Chen, P.R.

1993-11-05

This paper reports on a study of plasma bubbles or spread F irregularities, observed at equatorial observation stations, looked at in conjunction with measures of the quasi biennial oscillation (QBO) of the mean lower stratospheric winds. Plasma bubbles and spread F irregularities are thought to be different manifestations of the same basic event, distinguished mainly by the observational method. For the case of range spread F events, ionosonde data has revealed in the past daily and seasonal variations, effects due to the solar cycle, and dependence upon the geomagnetic field and longitudinal location. These relationships have been shown to bemore » statistical in nature, so the authors have looked for other relationships which might be more relational in nature. When correlation with QBO phase variations are investigated, there is an observed increase or decrease in the range spread F, dependent upon whether the QBO is in an easterly or westerly phase, and observed in the American sector or Indian/East African sector.« less

Long-term effects of guar gum in subjects with non-insulin-dependent diabetes mellitus.

PubMed

Groop, P H; Aro, A; Stenman, S; Groop, L

1993-10-01

The effects of 15 g guar gum/d on glycemic control, lipids, and insulin secretion were studied in 15 (8 male, 7 female) diet-treated subjects with non-insulin-dependent diabetes mellitus for 48 wk. Mean age (+/- SD) was 60 +/- 2 y (range 45-70 y), body mass index (in kg/m2) 28.6 +/- 0.9 (range 21.6 +/- 39.2), and duration of diabetes 6 +/- 1 y (range 2-14 y). Guar gum was preceded and followed by 8-wk placebo periods. Guar gum improved long-term glycemic control, postprandial glucose tolerance and lipid concentrations. The C-peptide response to a test meal increased by time during guar gum treatment, whereas the insulin response remained unchanged. This indicates that insulin secretion is enhanced by guar gum as reflected by increased C-peptide. A decreased molar ratio of insulin to C-peptide suggests that guar gum may increase hepatic insulin extraction. In conclusion, guar gum has favorable long-term effects on glycemic control and lipid concentrations.

Characteristics of Protons Exiting from a Polyethylene Converter Irradiated by Neutrons with Energies between 1 keV and 10 MeV

PubMed Central

Nikezic, D.; Shahmohammadi Beni, Mehrdad; Krstic, D.; Yu, K. N.

2016-01-01

Monte Carlo method has been used to determine the efficiency for proton production and to study the energy and angular distributions of the generated protons. The ENDF library of cross sections is used to simulate the interactions between the neutrons and the atoms in a polyethylene (PE) layer, while the ranges of protons with different energies in PE are determined using the Stopping and Range of Ions in Matter (SRIM) computer code. The efficiency of proton production increases with the PE layer thickness. However the proton escaping from a certain polyethylene volume is highly dependent on the neutron energy and target thickness, except for a very thin PE layer. The energy and angular distributions of protons are also estimated in the present paper, showing that, for the range of energy and thickness considered, the proton flux escaping is dependent on the PE layer thickness, with the presence of an optimal thickness for a fixed primary neutron energy. PMID:27362656

The incidence of pathological gambling among Native Americans treated for alcohol dependence.

PubMed

Elia, C; Jacobs, D F

1993-05-01

The prevalence rate of potential and pathological gambling was examined among Native American and Caucasian patients (n = 85) being treated for alcohol dependence. Previous studies with alcohol-dependent (mainly Caucasian) populations revealed 10-15% to have gambling problems. This study, the first to measure pathological gambling among a Native American population, utilized the South Oaks Gambling Screen and was administered in a group setting, between 1/91 and 4/91 on the alcohol treatment ward of the Ft. Meade Veterans Administration Hospital. Results showed that 22% of the Native Americans studied (compared to 7.3% Caucasian), scored in a range indicating a probable pathological gambling addiction. Furthermore, 41% of the Native Americans studied (compared to 21.3% Caucasian) admitted to some difficulty with gambling. Education and treatment is encouraged to help stem projected radical increases in pathological gambling and related problems among this cultural group as Native American gambling becomes widespread.

Novel application of species richness estimators to predict the host range of parasites.

PubMed

Watson, David M; Milner, Kirsty V; Leigh, Andrea

2017-01-01

Host range is a critical life history trait of parasites, influencing prevalence, virulence and ultimately determining their distributional extent. Current approaches to measure host range are sensitive to sampling effort, the number of known hosts increasing with more records. Here, we develop a novel application of results-based stopping rules to determine how many hosts should be sampled to yield stable estimates of the number of primary hosts within regions, then use species richness estimation to predict host ranges of parasites across their distributional ranges. We selected three mistletoe species (hemiparasitic plants in the Loranthaceae) to evaluate our approach: a strict host specialist (Amyema lucasii, dependent on a single host species), an intermediate species (Amyema quandang, dependent on hosts in one genus) and a generalist (Lysiana exocarpi, dependent on many genera across multiple families), comparing results from geographically-stratified surveys against known host lists derived from herbarium specimens. The results-based stopping rule (stop sampling bioregion once observed host richness exceeds 80% of the host richness predicted using the Abundance-based Coverage Estimator) worked well for most bioregions studied, being satisfied after three to six sampling plots (each representing 25 host trees) but was unreliable in those bioregions with high host richness or high proportions of rare hosts. Although generating stable predictions of host range with minimal variation among six estimators trialled, distribution-wide estimates fell well short of the number of hosts known from herbarium records. This mismatch, coupled with the discovery of nine previously unrecorded mistletoe-host combinations, further demonstrates the limited ecological relevance of simple host-parasite lists. By collecting estimates of host range of constrained completeness, our approach maximises sampling efficiency while generating comparable estimates of the number of primary hosts, with broad applicability to many host-parasite systems. Copyright © 2016 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

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

Richter, Christian; Pawelke, Joerg; Karsch, Leonhard

Purpose: The aim of this article is to investigate the energy dependence of the radiochromic film type, Gafchromic EBT-1, when scanned with a flatbed scanner for film readout. Methods: Dose response curves were determined for 12 different beam qualities ranging from a 10 kVp x-ray beam to a 15 MVp x-ray beam and include also two high energy electron beam qualities (6 and 18 MeV). The dose responses measured as net optical density (netOD) for the different beam qualities were normalized to the response of a reference beam quality (6 MVp). Results: A strong systematic energy dependence of the filmmore » response was found. The lower the effective beam energy, the less sensitive the EBT-1 films get. The maximum decrease in dose for the same film response between the 25 kVp and 6 MVp beam qualities was 44%. Additionally, a difference in energy dependence for different doses was discovered, meaning that higher doses show a smaller dependency on energy than lower doses. The maximum decrease in the normalized netOD was found to be 25% for a dose of 0.5 Gy relative to the normalized netOD for 10 Gy. Moreover, a scaling procedure is introduced, allowing the correction of the energy dependence for the investigated beam qualities and also for comparable x-ray beam qualities within the energy range studied. Conclusions: A strong energy dependence for EBT-1 radiochromic films was found. The films were readout with a flatbed scanner. If the effective beam energy is known, the energy dependence can be corrected with the introduced scaling procedure. Further investigation of the influence of the spectral band of the readout device on energy dependence is needed to understand the reason for the different energy dependences found in this and previous works.« less

Quantifying predator dependence in the functional response of generalist predators.

PubMed

Novak, Mark; Wolf, Christopher; Coblentz, Kyle E; Shepard, Isaac D

2017-06-01

A long-standing debate concerns how functional responses are best described. Theory suggests that ratio dependence is consistent with many food web patterns left unexplained by the simplest prey-dependent models. However, for logistical reasons, ratio dependence and predator dependence more generally have seen infrequent empirical evaluation and then only so in specialist predators, which are rare in nature. Here we develop an approach to simultaneously estimate the prey-specific attack rates and predator-specific interference (facilitation) rates of predators interacting with arbitrary numbers of prey and predator species in the field. We apply the approach to surveys and experiments involving two intertidal whelks and their full suite of potential prey. Our study provides strong evidence for predator dependence that is poorly described by the ratio dependent model over manipulated and natural ranges of species abundances. It also indicates how, for generalist predators, even the qualitative nature of predator dependence can be prey-specific. © 2017 John Wiley & Sons Ltd/CNRS.

Creep and stress rupture of oxide dispersion strengthened mechanically alloyed Inconel alloy MA 754

NASA Technical Reports Server (NTRS)

Howson, T. E.; Tien, J. K.; Stulga, J. E.

1980-01-01

The creep and stress rupture behavior of the mechanically alloyed oxide dispersion strengthened nickel-base alloy MA 754 was studied at 760, 982 and 1093 C. Tensile specimens with a fine, highly elongated grain structure, oriented parallel and perpendicular to the longitudinal grain direction were tested at various stresses in air under constant load. It was found that the apparent stress dependence was large, with power law exponents ranging from 19 to 33 over the temperature range studied. The creep activation energy, after correction for the temperature dependence of the elastic modulus, was close to but slightly larger than the activation energy for self diffusion. Rupture was intergranular and the rupture ductility as measured by percentage elongation was generally low, with values ranging from 0.5 to 16 pct. The creep properties are rationalized by describing the creep rates in terms of an effective stress which is the applied stress minus a resisting stress consistent with the alloy microstructure. Values of the resisting stress obtained through a curve fitting procedure are found to be close to the values of the particle by-pass stress for this oxide dispersion strengthened alloy, as calculated from the measured oxide particle distribution.

Nano confinement effects on dynamic and viscoelastic properties of Selenium Films

NASA Astrophysics Data System (ADS)

Yoon, Heedong; McKenna, Gregory

2015-03-01

In current study, we use a novel nano bubble inflation technique to study nano confinement effects on the dynamic and viscoelastic properties of physical vapor deposited Selenium films. Film thicknesses ranged from 60 to 260 nm. Creep experiments were performed for the temperatures ranging from Tg,macroscopic-14 °C to Tg,\\ macroscopic + 19 °C. Time temperature superposition and time thickness superposition were applied to create reduced creep curves, and those were compared with macroscopic data [J. Non-Cryst. Solids. 2002, 307, 790-801]. The results showed that the time temperature superposition was applicable in the glassy relaxation regime to the steady-state plateau regime. However in the long time response of the creep compliance, time thickness superposition failed due to the thickness dependence on the steady-state plateau. It was observed that the steady state compliance increased with film thickness. The thickness dependence on the plateau stiffening followed a power law of DPlateau ~ h2.46, which is greater than observed in organic polymers where the exponents observed range from 0.83 to 2.0 [Macromolecules. 2012, 45 (5), 2453-2459]. National Science Foundation Grant No. CHE 1112416 and John R. Bradford Endowment at Texas Tech

Investigations on Cu2+-substituted Ni-Zn ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Amarjeet; Kumar, Vinod

2016-11-01

CuxNi(1-x)/2Zn(1-x)/2Fe2O4 (x = 0.1, 0.3 and 0.5) nanoparticles were prepared by chemical co-precipitation method. The developed nanoparticles were characterized for structural properties by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Peak position in the X-ray diffraction pattern confirmed the single spinel phase of the developed particles. Infrared (IR) spectroscopy in mid-IR range showed the presence of characteristic absorption bands corresponding to octahedral and tetrahedral bonds in the spinel structure of prepared samples. Thermo-gravimetric analysis (TGA) measurements showed a considerable weight loss in the developed samples above 700∘C. Frequency dependence of the electrical properties of the developed material pellets was studied in the frequency range of 1 kHz-5 MHz. Temperature dependence of the dielectric constant of Cu0.1Ni0.45Zn0.45Fe2O4 was studied at different temperatures, i.e. at 425, 450 and 475 K, in the frequency range of 1 kHz-5 MHz. It was found that the electrical conductivity decreases with increasing Cu2+ ion content while it increases with the increase in temperature.

Metal ion transport quantified by ICP-MS in intact cells

PubMed Central

Figueroa, Julio A. Landero; Stiner, Cory A.; Radzyukevich, Tatiana L.; Heiny, Judith A.

2016-01-01

The use of ICP-MS to measure metal ion content in biological tissues offers a highly sensitive means to study metal-dependent physiological processes. Here we describe the application of ICP-MS to measure membrane transport of Rb and K ions by the Na,K-ATPase in mouse skeletal muscles and human red blood cells. The ICP-MS method provides greater precision and statistical power than possible with conventional tracer flux methods. The method is widely applicable to studies of other metal ion transporters and metal-dependent processes in a range of cell types and conditions. PMID:26838181

Temperature dependent growth of GaN nanowires using CVD technique

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

Kumar, Mukesh, E-mail: mukeshjihrnp@gmail.com; Singh, R.; Kumar, Vikram

2016-05-23

Growth of GaN nanowires have been carried out on sapphire substrates with Au as a catalyst using chemical vapour deposition technique. GaN nanowires growth have been studied with the experimental parameter as growth temperature. Diameter of grown GaN nanowires are in the range of 50 nm to 100 nm while the nanowire length depends on growth temperature. Morphology of the GaN nanowires have been studied by scanning electron microscopy. Crystalline nature has been observed by XRD patterns. Optical properties of grown GaN nanowires have been investigated by photoluminescence spectra.

Metal ion transport quantified by ICP-MS in intact cells.

PubMed

Figueroa, Julio A Landero; Stiner, Cory A; Radzyukevich, Tatiana L; Heiny, Judith A

2016-02-03

The use of ICP-MS to measure metal ion content in biological tissues offers a highly sensitive means to study metal-dependent physiological processes. Here we describe the application of ICP-MS to measure membrane transport of Rb and K ions by the Na,K-ATPase in mouse skeletal muscles and human red blood cells. The ICP-MS method provides greater precision and statistical power than possible with conventional tracer flux methods. The method is widely applicable to studies of other metal ion transporters and metal-dependent processes in a range of cell types and conditions.

Assortativeness and information in scale-free networks

NASA Astrophysics Data System (ADS)

Piraveenan, M.; Prokopenko, M.; Zomaya, A. Y.

2009-02-01

We analyze Shannon information of scale-free networks in terms of their assortativeness, and identify classes of networks according to the dependency of the joint remaining degree distribution on the assortativeness. We conjecture that these classes comprise minimalistic and maximalistic networks in terms of Shannon information. For the studied classes, the information is shown to depend non-linearly on the absolute value of the assortativeness, with the dominant term of the relationship being a power-law. We exemplify this dependency using a range of real-world networks. Optimization of scale-free networks according to information they contain depends on the landscape of parameters’ search-space, and we identify two regions of interest: a slope region and a stability region. In the slope region, there is more freedom to generate and evaluate candidate networks since the information content can be changed easily by modifying only the assortativeness, while even a small change in the power-law’s scaling exponent brings a reward in a higher rate of information change. This feature may explain why the exponents of real-world scale-free networks are within a certain range, defined by the slope and stability regions.

On the penetration of a hot diapir through a strongly temperature-dependent viscosity medium

NASA Technical Reports Server (NTRS)

Daly, S. F.; Raefsky, A.

1985-01-01

The ascent of a hot spherical body through a fluid with a strongly temperature-dependent viscosity has been studied using an axisymmetric finite element method. Numerical solutions range over Peclet numbers of 0.1 - 1000 from constant viscosity up to viscosity variations of 100,000. Both rigid and stress-free boundary conditions were applied at the surface of the sphere. The dependence of drag on viscosity variation was shown to have no dependence on the stress boundary condition except for a Stokes flow scaling factor. A Nusselt number parameterization based on the stress-free constant viscosity functional dependence on the Peclet number scaled by a parameter depending on the viscosity structure fits both stress-free and rigid boundary condition data above viscosity variations of 100. The temperature scale height was determined as a function of sphere radius. For the simple physical model studied in this paper pre-heating is required to reduce the ambient viscosity of the country rock to less than 10 to the 22nd sq cm/s in order for a 10 km diapir to penetrate a distance of several radii.

Temperature dependence of direct current conductivity in Ag-ED20 nanocomposite films

NASA Astrophysics Data System (ADS)

Novikov, G. F.; Rabenok, E. V.; Bogdanova, L. M.; Irzhak, V. I.

2017-10-01

The effect of silver nanoparticles (NPs) in the concentration range of ≤0.8 wt % have on direct current conductivity σdc of Ag-ED20 nanocomposite is studied by method of broadband dielectric spectroscopy (10-2-105 Hz) method of broadband dielectric spectroscopy. It is found that temperature dependence σdc consists of two sections: above the glass transition temperature ( T g), the dependence corresponds to the empirical Vogel-Fulcher-Tammann law (Vogel temperature T 0 does not depend on the NP concentration); below T g, the dependence is Arrhenius with activation energy E a ≈ 1.2 eV. In the region where T > T g, the σdc value grows along with NP concentration. It is concluded that the observed broken form of the temperature dependence is apparently due to a change in the conduction mechanism after the freezing of ion mobility at temperatures below T g.

Water clusters in amorphous pharmaceuticals.

PubMed

Authelin, Jean-Rene; MacKenzie, Alan P; Rasmussen, Don H; Shalaev, Evgenyi Y

2014-09-01

Amorphous materials, although lacking the long-range translational and rotational order of crystalline and liquid crystalline materials, possess certain local (short-range) structure. This paper reviews the distribution of one particular component present in all amorphous pharmaceuticals, that is, water. Based on the current understanding of the structure of water, water molecules can exist in either unclustered form or as aggregates (clusters) of different sizes and geometries. Water clusters are reported in a range of amorphous systems including carbohydrates and their aqueous solutions, synthetic polymers, and proteins. Evidence of water clustering is obtained by various methods that include neutron and X-ray scattering, molecular dynamics simulation, water sorption isotherm, concentration dependence of the calorimetric Tg , dielectric relaxation, and nuclear magnetic resonance. A review of the published data suggests that clustering depends on water concentration, with unclustered water molecules existing at low water contents, whereas clusters form at intermediate water contents. The transition from water clusters to unclustered water molecules can be expected to change water dependence of pharmaceutical properties, such as rates of degradation. We conclude that a mechanistic understanding of the impact of water on the stability of amorphous pharmaceuticals would require systematic studies of water distribution and clustering, while such investigations are lacking. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Yeast-based biosensors: design and applications.

PubMed

Adeniran, Adebola; Sherer, Michael; Tyo, Keith E J

2015-02-01

Yeast-based biosensing (YBB) is an exciting research area, as many studies have demonstrated the use of yeasts to accurately detect specific molecules. Biosensors incorporating various yeasts have been reported to detect an incredibly large range of molecules including but not limited to odorants, metals, intracellular metabolites, carcinogens, lactate, alcohols, and sugars. We review the detection strategies available for different types of analytes, as well as the wide range of output methods that have been incorporated with yeast biosensors. We group biosensors into two categories: those that are dependent upon transcription of a gene to report the detection of a desired molecule and those that are independent of this reporting mechanism. Transcription-dependent biosensors frequently depend on heterologous expression of sensing elements from non-yeast organisms, a strategy that has greatly expanded the range of molecules available for detection by YBBs. Transcription-independent biosensors circumvent the problem of sensing difficult-to-detect analytes by instead relying on yeast metabolism to generate easily detected molecules when the analyte is present. The use of yeast as the sensing element in biosensors has proven to be successful and continues to hold great promise for a variety of applications. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

Electrical potentials in bone induced by ultrasound irradiation in the megahertz range

NASA Astrophysics Data System (ADS)

Okino, M.; Coutelou, S.; Mizuno, K.; Yanagitani, T.; Matsukawa, M.

2013-09-01

Low frequency mechanical studies have reported the contribution of stress-induced electrical potentials to bone metabolism. However, the healing mechanism of bone fractures by low intensity ultrasound is not yet clear. We demonstrate that bone can generate electrical potentials by ultrasound irradiation in the MHz range. Electrical potentials were obtained from the output of bovine cortical bone transducers. In the range of 0.7-2.5 MHz, sensitivities of bone transducers were around 1/1000 of a poly (vinylidene fluoride) ultrasonic transducer and did not depend on magnitude and alignment of hydroxyapatite crystallites in bone.

Multifactor analysis of multiscaling in volatility return intervals.

PubMed

Wang, Fengzhong; Yamasaki, Kazuko; Havlin, Shlomo; Stanley, H Eugene

2009-01-01

We study the volatility time series of 1137 most traded stocks in the U.S. stock markets for the two-year period 2001-2002 and analyze their return intervals tau , which are time intervals between volatilities above a given threshold q . We explore the probability density function of tau , P_(q)(tau) , assuming a stretched exponential function, P_(q)(tau) approximately e;(-tau;(gamma)) . We find that the exponent gamma depends on the threshold in the range between q=1 and 6 standard deviations of the volatility. This finding supports the multiscaling nature of the return interval distribution. To better understand the multiscaling origin, we study how gamma depends on four essential factors, capitalization, risk, number of trades, and return. We show that gamma depends on the capitalization, risk, and return but almost does not depend on the number of trades. This suggests that gamma relates to the portfolio selection but not on the market activity. To further characterize the multiscaling of individual stocks, we fit the moments of tau , mu_(m) identical with(tautau);(m);(1m) , in the range of 10

Multifactor analysis of multiscaling in volatility return intervals

NASA Astrophysics Data System (ADS)

Wang, Fengzhong; Yamasaki, Kazuko; Havlin, Shlomo; Stanley, H. Eugene

2009-01-01

We study the volatility time series of 1137 most traded stocks in the U.S. stock markets for the two-year period 2001-2002 and analyze their return intervals τ , which are time intervals between volatilities above a given threshold q . We explore the probability density function of τ , Pq(τ) , assuming a stretched exponential function, Pq(τ)˜e-τγ . We find that the exponent γ depends on the threshold in the range between q=1 and 6 standard deviations of the volatility. This finding supports the multiscaling nature of the return interval distribution. To better understand the multiscaling origin, we study how γ depends on four essential factors, capitalization, risk, number of trades, and return. We show that γ depends on the capitalization, risk, and return but almost does not depend on the number of trades. This suggests that γ relates to the portfolio selection but not on the market activity. To further characterize the multiscaling of individual stocks, we fit the moments of τ , μm≡⟨(τ/⟨τ⟩)m⟩1/m , in the range of 10<⟨τ⟩⩽100 by a power law, μm˜⟨τ⟩δ . The exponent δ is found also to depend on the capitalization, risk, and return but not on the number of trades, and its tendency is opposite to that of γ . Moreover, we show that δ decreases with increasing γ approximately by a linear relation. The return intervals demonstrate the temporal structure of volatilities and our findings suggest that their multiscaling features may be helpful for portfolio optimization.

In vivo voltage-dependent influences on summation of synaptic potentials in neurons of the lateral nucleus of the amygdala

PubMed Central

Rosenkranz, J. Amiel

2012-01-01

The amygdala has a fundamental role in driving affective behaviors in response to sensory cues. To accomplish this, neurons of the lateral nucleus (LAT) must integrate a large number of synaptic inputs. A wide range of factors influence synaptic integration, including membrane potential, voltage-gated ion channels and GABAergic inhibition. However, little is known about how these factors modulate integration of synaptic inputs in LAT neurons in vivo. The purpose of this study was to determine the voltage-dependent factors that modify in vivo integration of synaptic inputs in the soma of LAT neurons. In vivo intracellular recordings from anesthetized rats were used to measure post-synaptic potentials (PSPs) and clusters of PSPs across a range of membrane potentials. These studies found that the relationship between membrane potential and PSP clusters was sublinear, due to a reduction of cluster amplitude and area at depolarized membrane potentials. In combination with intracellular delivery of pharmacological agents, it was found that the voltage-dependent suppression of PSP clusters was sensitive to tetraethylammonium (TEA), but not cesium or a blocker of fast GABAergic inhibition. These findings indicate that integration of PSPs in LAT neurons in vivo is strongly modified by somatic membrane potential, likely through voltage-dependent TEA-sensitive potassium channels. Conditions that lead to a shift in membrane potential, or a modulation of the number or function of these ion channels will lead to a more uniform capacity for integration across voltages, and perhaps greatly facilitate amygdala-dependent behaviors. PMID:22989917

The thermal conductivity of 1-chloro-1,1-difluoroethane (HCFC-142b)

NASA Astrophysics Data System (ADS)

Sousa, A. T.; Fialho, P. S.; Nieto de Castro, C. A.; Tufeu, R.; Le Neindre, B.

1992-05-01

The thermal conductivity of 1-chloro-1,1-difluoroethane (HCFC-142b) has been measured in the temperature range 290 to 504 K and pressures up to 20 MPa with a concentric-cylinder apparatus operating in a steady-state mode. These temperature and pressure ranges cover all fluid states. The estimated accuracy of the method is about 2%. The density dependence of the thermal conductivity has been studied in the liquid region.

Development of NTD Ge Sensors for Superconducting Bolometer

NASA Astrophysics Data System (ADS)

Garai, A.; Mathimalar, S.; Singh, V.; Dokania, N.; Nanal, V.; Pillay, R. G.; Ramakrishnan, S.; Shrivastava, A.; Jagadeesan, K. C.; Thakare, S. V.

2016-08-01

Neutron transmutation-doped (NTD) Ge sensors have been prepared by irradiating device-grade Ge with thermal neutrons at Dhruva reactor, BARC, Mumbai. These sensors are intended to be used for the study of neutrinoless double beta decay in ^{124}Sn with a superconducting Tin bolometer. Resistance measurements are performed on NTD Ge sensors in the temperature range 100-350 mK. The observed temperature dependence is found to be consistent with the variable-range hopping mechanism.

Phase Behavior in Blends of Asymmetrical Polyolefins

NASA Astrophysics Data System (ADS)

Nedoma, Alisyn Jenise

This dissertation presents the most comprehensive study of chi to date for a single pair of homopolymers. Polyisobutylene (component B) and deuterated polybutadiene with 63 % 1,2 addition (component C) were selected for this study because they exhibit a large window of miscibility and may be tailored to cross the spinodal at experimentally accessible temperatures. Binary blends were designed across a range of values for NB/ NC and the composition of the blend, φB, to study the effect of these parameters on the measured value, chi sc. In addition to the strict temperature dependence presumed for chi, this study documented a composition and molecular weight dependence. The empirical expression for chisc, measured using small angle neutron scattering, was three times more dependent on composition then the expression for chi used to predict thermodynamic behavior. Despite this three-fold diminished dependence on φB, the composition-dependent chi profoundly affected the phase behavior of binary blends. A range of values was studied for NB/ NC ≤ 1, and in all cases φB,cirt was found to be < 0.5, in stark contrast to the expectation of Flory-Huggins Theory that φB,crit ≥ 0.5. This effect was shown to result from the combined effects of a composition-dependent chi and N B/NC removed from values of 1. Remarkable agreement was obtained between the predicted phase diagrams and measured phase transitions, over a range of values for NB/ NC and φB, by accounting for the composition and molecular weight dependence of chi. The miscibility of binary B/C blends was used as the basis for designing a diblock copolymer (component A-C) to order immiscible binary blends of polyisobutylene and deuterated polybutadiene with 89 % 1,2 addition (component A). The copolymer comprised one block chemically identical to component C (miscible in component B) and one block chemically identical to component A. This is in contrast to the majority of ternary blend studies which comprise A/B/A-B polymer systems with neutral interactions between each homopolymer and the corresponding block of the diblock copolymer. Ternary A/B/A-C blends exhibit a favorable interaction between the B homopolymer and C block, demonstrated by the miscibility of B/C blends. The A-C diblock copolymer surfactant can produce microstructures when added to A/B blends at much lower concentrations of copolymer than for an analagous A-B copolymer. This dissertation introduces the use of lamellar structure factor that fits scattering profiles unsuitable for the microemulsion fit. In addition, the lamellar fits include as adjustable parameters the size of each microdomain and corresponding interfacial width. These fit values agree quantitatively with independently generated predictions using self-consistent field theory, indicating a broad understanding of the physical parameters that affect thermodynamic behavior in the A/B/A-C system studied. This dissertation presents a study for which the concentration of diblock copolymer was fixed and the composition of the A and B homopolymers was systematically varied across a range of compositions including φA,crit. The experiment corresponded to tracing the copolymer isopleth on a ternary phase prism. Theoretical groups have predicted a rich phase behavior along the isopleth for similar ternary systems, however, the observed phase behavior was quantitatively identical for all blends studied. Self-consistent field theory predictions agreed with fit values of the domain spacing and microdomain widths. There was no discernible correlation between φA and phase behavior. This finding, and that of the study with critical A/B/A-C blends, together suggest that NA/NB correlates strongly with the phase behavior of a blend, while φ A does not. This relationship, captured by mean-field theory, provides a simple method for tuning the phase behavior of polymer nanocomposites without using additional surfactant. (Abstract shortened by UMI.)

Temperature Dependence of Power Reflectivity of the First-Wall Materials in the Synchrotron Radiation Range

NASA Astrophysics Data System (ADS)

Takada, Noriharu; Nagatsu, Masaaki; Shimada, Michiya

1995-07-01

The temperature dependence of power reflectivity in the synchrotron radiation range was measured for candidate first-wall materials of the fusion reactor, such as B4C-coated isotropic graphite, C/C composite material, silicon carbide (SiC), tungsten (W), molybdenum (Mo) and SUS-316. The measurements were carried out using a vacuum vessel with a pressure of about 3 mTorr to avoid oxidation. Distinct temperature dependence of reflectivity was observed only for B4C-coated isotropic graphite. For the other materials, power reflectivities were insensitive to temperature in the range from 300 K to ˜900 K. Theoretical analysis of the results is also presented.

Nonempirical range-separated hybrid functionals for solids and molecules

DOE PAGES

Skone, Jonathan H.; Govoni, Marco; Galli, Giulia

2016-06-03

Dielectric-dependent hybrid (DDH) functionals were recently shown to yield accurate energy gaps and dielectric constants for a wide variety of solids, at a computational cost considerably less than that of GW calculations. The fraction of exact exchange included in the definition of DDH functionals depends (self-consistently) on the dielectric constant of the material. Here we introduce a range-separated (RS) version of DDH functionals where short and long-range components are matched using system dependent, non-empirical parameters. We show that RS DDHs yield accurate electronic properties of inorganic and organic solids, including energy gaps and absolute ionization potentials. Moreover, we show thatmore » these functionals may be generalized to finite systems.« less

Linear analysis of time dependent properties of Child-Langmuir flow

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

Rokhlenko, A.

We continue our analysis of the time dependent behavior of the electron flow in the Child-Langmuir system, removing an approximation used earlier. We find a modified set of oscillatory decaying modes with frequencies of the same order as the inverse of the electron transient time. This range (typically MHz) allows simple experimental detection and maybe exploitation. We then study the time evolution of the current in response to a slow change of the anode voltage where the same modes of oscillations appear too. The cathode current in this case is systematically advanced or retarded depending on the direction of themore » voltage change.« less

The effect of temperature and dot size on the spectral properties of colloidal InP/ZnS core-shell quantum dots.

PubMed

Narayanaswamy, Arun; Feiner, L F; Meijerink, A; van der Zaag, P J

2009-09-22

Visual color changes between 300 and 510 K were observed in the photoluminescence (PL) of colloidal InP/ZnS core-shell nanocrystals. A subsequent study of PL spectra in the range 2-510 K and fitting the temperature dependent line shift and line width to theoretical models show that the dominant (dephasing) interaction is due to scattering by acoustic phonons of about 23 meV. Low temperature photoluminescence excitation measurements show that the excitonic band gap depends approximately inversely linearly on the quantum dot size d, which is distinctly weaker than the dependence predicted by current theories.

Linear analysis of time dependent properties of Child-Langmuir flow

NASA Astrophysics Data System (ADS)

Rokhlenko, A.

2013-01-01

We continue our analysis of the time dependent behavior of the electron flow in the Child-Langmuir system, removing an approximation used earlier. We find a modified set of oscillatory decaying modes with frequencies of the same order as the inverse of the electron transient time. This range (typically MHz) allows simple experimental detection and maybe exploitation. We then study the time evolution of the current in response to a slow change of the anode voltage where the same modes of oscillations appear too. The cathode current in this case is systematically advanced or retarded depending on the direction of the voltage change.

Compositional dependence of the band gap in Ga(NAsP) quantum well heterostructures

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

Jandieri, K., E-mail: kakhaber.jandieri@physik.uni-marburg.de; Ludewig, P.; Wegele, T.

We present experimental and theoretical studies of the composition dependence of the direct band gap energy in Ga(NAsP)/GaP quantum well heterostructures grown on either (001) GaP- or Si-substrates. The theoretical description takes into account the band anti-crossing model for the conduction band as well as the modification of the valence subband structure due to the strain resulting from the pseudomorphic epitaxial growth on the respective substrate. The composition dependence of the direct band gap of Ga(NAsP) is obtained for a wide range of nitrogen and phosphorus contents relevant for laser applications on Si-substrate.

Laser absorption waves in metallic capillaries

NASA Astrophysics Data System (ADS)

Anisimov, V. N.; Arutiunian, R. V.; Bol'Shov, L. A.; Kanevskii, M. F.; Kondrashov, V. V.

1987-07-01

The propagation of laser absorption waves in metallic capillaries was studied experimentally and numerically during pulsed exposure to CO2 laser radiation. The dependence of the plasma front propagation rate on the initial air pressure in the capillary is determined. In a broad range of parameters, the formation time of the optically opaque plasma layer is governed by the total laser pulse energy from the beginning of the exposure to the instant screening appears, and is weakly dependent on the pulse shape and gas pressure.

Dense simple plasmas as high-temperature liquid simple metals

NASA Technical Reports Server (NTRS)

Perrot, F.

1990-01-01

The thermodynamic properties of dense plasmas considered as high-temperature liquid metals are studied. An attempt is made to show that the neutral pseudoatom picture of liquid simple metals may be extended for describing plasmas in ranges of densities and temperatures where their electronic structure remains 'simple'. The primary features of the model when applied to plasmas include the temperature-dependent self-consistent calculation of the electron charge density and the determination of a density and temperature-dependent ionization state.

Shape and edge dependent electronic and magnetic properties of silicene nano-flakes

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

Mohan, Brij, E-mail: brijmohanhpu@yahoo.com; Pooja,; Ahluwalia, P. K.

2015-06-24

We performed first-principle study of the geometric, electronic and magnetic properties of arm-chair and zigzag edge silicene nano-flakes of triangular and hexagonal shapes. Electronic properties of silicene nano-flakes show strong dependence on their edge structure and shape. The considered nanostructures shows energy gap ranging ∼ 0.4 – 1.0 eV. Zigzag edged triangular nano-flake is magnetic and semiconducting in nature with 4.0 µ{sub B} magnetic moment and ∼ 0.4 eV energy gap.

Spreading dynamics of 2D dipolar Langmuir monolayer phases.

PubMed

Heinig, P; Wurlitzer, S; Fischer, Th M

2004-07-01

We study the spreading of a liquid 2D dipolar droplet in a Langmuir monolayer. Interfacial tensions (line tensions) and microscopic contact angles depend on the scale on which they are probed and obey a scaling law. Assuming rapid equilibration of the microscopic contact angle and ideal slippage of the 2D solid/liquid and solid/gas boundary, the driving force of spreading is merely expressed by the shape-dependent long-range interaction integrals. We obtain good agreement between experiment and numerical simulations using this theory.

Resolution-dependent behavior of subgrid-scale vertical transport in the Zhang-McFarlane convection parameterization

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

Xiao, Heng; Gustafson, Jr., William I.; Hagos, Samson M.

2015-04-18

With this study, to better understand the behavior of quasi-equilibrium-based convection parameterizations at higher resolution, we use a diagnostic framework to examine the resolution-dependence of subgrid-scale vertical transport of moist static energy as parameterized by the Zhang-McFarlane convection parameterization (ZM). Grid-scale input to ZM is supplied by coarsening output from cloud-resolving model (CRM) simulations onto subdomains ranging in size from 8 × 8 to 256 × 256 km 2s.

Disaccommodation in LaMnO3.075

NASA Astrophysics Data System (ADS)

Muroi, M.; Street, R.; Cochrane, J. W.; Russell, G. J.

2000-10-01

The time dependence of low-field ac susceptibility has been studied on the cation-deficient perovskite manganite LaMnO3.075. It is found that the ac susceptibility \\|χ\\| decreases with time over a wide temperature range below Tc (122 K) and the decay of \\|χ\\| is roughly proportional to the logarithm of time after demagnetization. It is argued that the time dependence of \\|χ\\|, or disaccommodation, arises from progressive domain-wall stabilization through induced exchange interaction, as well as induced magnetocrystalline anisotropy.

An integrated data analysis approach to investigating measurement equivalence of DSM nicotine dependence symptoms.

PubMed

Rose, Jennifer S; Dierker, Lisa C; Hedeker, Donald; Mermelstein, Robin

2013-04-01

Research identifying nicotine dependence (ND) symptoms most appropriate for measurement of adolescent ND and invariant across the range of smoking exposure is hampered by limited sample size and variability of smoking behavior within independent studies. Integrative data analysis, the process of pooling and analyzing data from multiple studies, produces larger and more heterogeneous samples with which to evaluate measurement equivalence across the full continuum of smoking quantity and frequency. Data from two studies were pooled to obtain a large sample of adolescent and young adult smokers with considerable variability in smoking. We used moderated nonlinear factor analysis, which produces study equivalent ND scores, to simultaneously evaluate whether 14 DSM ND symptoms had equivalent psychometric properties (1) at different levels of smoking frequency and (2) across a continuous range of smoking quantity, after accounting for study differences. Nine of 14 symptoms were equivalent across levels of smoking frequency and quantity in probability of endorsement at different levels of ND and in ability to discriminate between levels of ND severity. A more precise ND factor score accounted for study and smoking related differences in symptom psychometric properties. DSM-IV symptoms may be used to reliably assess ND in young populations across a wide range of smoking quantity and frequency and within both nationally representative and geographically restricted samples with different study designs. Symptoms shared across studies produced an equivalently scaled ND factor score, demonstrating that integrating data for the purpose of studying ND in young smokers is viable. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

The size distribution of interstellar grains

NASA Technical Reports Server (NTRS)

Witt, Adolf N.

1987-01-01

Three major areas involving interstellar grains were investigated. First, studies were performed of scattering in reflection nebulae with the goal of deriving scattering characteristics of dust grains such as the albedo and the phase function asymmetry throughout the visible and the ultraviolet. Secondly, studies were performed of the wavelength dependence of interstellar extinction designed to demonstrate the wide range of grain size distributions naturally occurring in individual clouds in different parts of the galaxy. And thirdly, studies were also performed of the ultraviolet powered emission of dust grains in the 0.5 to 1.0 micron wavelength range in reflection nebulae. Findings considered of major importance are highlighted.

A stochastic chemical dynamic approach to correlate autoimmunity and optimal vitamin-D range.

PubMed

Roy, Susmita; Shrinivas, Krishna; Bagchi, Biman

2014-01-01

Motivated by several recent experimental observations that vitamin-D could interact with antigen presenting cells (APCs) and T-lymphocyte cells (T-cells) to promote and to regulate different stages of immune response, we developed a coarse grained but general kinetic model in an attempt to capture the role of vitamin-D in immunomodulatory responses. Our kinetic model, developed using the ideas of chemical network theory, leads to a system of nine coupled equations that we solve both by direct and by stochastic (Gillespie) methods. Both the analyses consistently provide detail information on the dependence of immune response to the variation of critical rate parameters. We find that although vitamin-D plays a negligible role in the initial immune response, it exerts a profound influence in the long term, especially in helping the system to achieve a new, stable steady state. The study explores the role of vitamin-D in preserving an observed bistability in the phase diagram (spanned by system parameters) of immune regulation, thus allowing the response to tolerate a wide range of pathogenic stimulation which could help in resisting autoimmune diseases. We also study how vitamin-D affects the time dependent population of dendritic cells that connect between innate and adaptive immune responses. Variations in dose dependent response of anti-inflammatory and pro-inflammatory T-cell populations to vitamin-D correlate well with recent experimental results. Our kinetic model allows for an estimation of the range of optimum level of vitamin-D required for smooth functioning of the immune system and for control of both hyper-regulation and inflammation. Most importantly, the present study reveals that an overdose or toxic level of vitamin-D or any steroid analogue could give rise to too large a tolerant response, leading to an inefficacy in adaptive immune function.

pH-Dependent Solubility and Dissolution Behavior of Carvedilol--Case Example of a Weakly Basic BCS Class II Drug.

PubMed

Hamed, Rania; Awadallah, Areeg; Sunoqrot, Suhair; Tarawneh, Ola; Nazzal, Sami; AlBaraghthi, Tamadur; Al Sayyad, Jihan; Abbas, Aiman

2016-04-01

The objective of this study was to investigate the pH-dependent solubility and dissolution of weakly basic Biopharmaceutical Classification Systems (BCS) class II drugs, characterized by low solubility and high permeability, using carvedilol, a weak base with a pK a value of 7.8, as a model drug. A series of solubility and in vitro dissolution studies was carried out using media that simulate the gastric and intestinal fluids and cover the physiological pH range of the GI from 1.2 to 7.8. The effect of ionic strength, buffer capacity, and buffer species of the dissolution media on the solubility and dissolution behavior of carvedilol was also investigated. The study revealed that carvedilol exhibited a typical weak base pH-dependent solubility profile with a high solubility at low pH (545.1-2591.4 μg/mL within the pH range 1.2-5.0) and low solubility at high pH (5.8-51.9 μg/mL within the pH range 6.5-7.8). The dissolution behavior of carvedilol was consistent with the solubility results, where carvedilol release was complete (95.8-98.2% released within 60 min) in media simulating the gastric fluid (pH 1.2-5.0) and relatively low (15.9-86.2% released within 240 min) in media simulating the intestinal fluid (pH 6.5-7.8). It was found that the buffer species of the dissolution media may influence the solubility and consequently the percentage of carvedilol released by forming carvedilol salts of varying solubilities. Carvedilol solubility and dissolution decreased with increasing ionic strength, while lowering the buffer capacity resulted in a decrease in carvedilol solubility and dissolution rate.

Age-dependent effect of Alzheimer’s risk variant of CLU on EEG alpha rhythm in non-demented adults

PubMed Central

Ponomareva, Natalya; Andreeva, Tatiana; Protasova, Maria; Shagam, Lev; Malina, Daria; Goltsov, Andrei; Fokin, Vitaly; Mitrofanov, Andrei; Rogaev, Evgeny

2013-01-01

Polymorphism in the genomic region harboring the CLU gene (rs11136000) has been associated with the risk for Alzheimer’s disease (AD). CLU C allele is assumed to confer risk for AD and the allele T may have a protective effect. We investigated the influence of the AD-associated CLU genotype on a common neurophysiological trait of brain activity (resting-state alpha-rhythm activity) in non-demented adults and elucidated whether this influence is modified over the course of aging. We examined quantitative electroencephalography (EEG) in a cohort of non-demented individuals (age range 20–80) divided into young (age range 20–50) and old (age range 51–80) cohorts and stratified by CLU polymorphism. To rule out the effect of the apolipoprotein E (ApoE) genotype on EEG characteristics, only subjects without the ApoE ε4 allele were included in the study. The homozygous presence of the AD risk variant CLU CC in non-demented subjects was associated with an increase of alpha3 absolute power. Moreover, the influence of CLU genotype on alpha3 was found to be higher in the subjects older than 50 years of age. The study also showed age-dependent alterations of alpha topographic distribution that occur independently of the CLU genotype. The increase of upper alpha power has been associated with hippocampal atrophy in patients with mild cognitive impairment (Moretti etal., 2012a). In our study, the CLU CC-dependent increase in upper alpha rhythm, particularly enhanced in elderly non-demented individuals, may imply that the genotype is related to preclinical dysregulation of hippocampal neurophysiology in aging and that this factor may contribute to the pathogenesis of AD. PMID:24379779

NMR relaxation studies in doped poly-3-methylthiophene

NASA Astrophysics Data System (ADS)

Singh, K. Jugeshwar; Clark, W. G.; Gaidos, G.; Reyes, A. P.; Kuhns, P.; Thompson, J. D.; Menon, R.; Ramesh, K. P.

2015-05-01

NMR relaxation rates (1 /T1 ), magnetic susceptibility, and electrical conductivity studies in doped poly-3-methylthiophene are reported in this paper. The magnetic susceptibility data show the contributions from both Pauli and Curie spins, with the size of the Pauli term depending strongly on the doping level. Proton and fluorine NMR relaxation rates have been studied as a function of temperature (3-300 K) and field (for protons at 0.9, 9.0, 16.4, and 23.4 T, and for fluorine at 9.0 T). The temperature dependence of T1 is classified into three regimes: (a) For T <(g μBB /2 kB ) , the relaxation mechanism follows a modified Korringa relation due to electron-electron interactions and disorder. 1H - T1 is due to the electron-nuclear dipolar interaction in addition to the contact term. (b) For the intermediate temperature range (g μBB /2 kB )

Moment expansion for ionospheric range error

NASA Technical Reports Server (NTRS)

Mallinckrodt, A.; Reich, R.; Parker, H.; Berbert, J.

1972-01-01

On a plane earth, the ionospheric or tropospheric range error depends only on the total refractivity content or zeroth moment of the refracting layer and the elevation angle. On a spherical earth, however, the dependence is more complex; so for more accurate results it has been necessary to resort to complex ray-tracing calculations. A simple, high-accuracy alternative to the ray-tracing calculation is presented. By appropriate expansion of the angular dependence in the ray-tracing integral in a power series in height, an expression is obtained for the range error in terms of a simple function of elevation angle, E, at the expansion height and of the mth moment of the refractivity, N, distribution about the expansion height. The rapidity of convergence is heavily dependent on the choice of expansion height. For expansion heights in the neighborhood of the centroid of the layer (300-490 km), the expansion to N = 2 (three terms) gives results accurate to about 0.4% at E = 10 deg. As an analytic tool, the expansion affords some insight on the influence of layer shape on range errors in special problems.

Designing Intervention Studies: Selected Populations, Range Restrictions, and Statistical Power

PubMed Central

Miciak, Jeremy; Taylor, W. Pat; Stuebing, Karla K.; Fletcher, Jack M.; Vaughn, Sharon

2016-01-01

An appropriate estimate of statistical power is critical for the design of intervention studies. Although the inclusion of a pretest covariate in the test of the primary outcome can increase statistical power, samples selected on the basis of pretest performance may demonstrate range restriction on the selection measure and other correlated measures. This can result in attenuated pretest-posttest correlations, reducing the variance explained by the pretest covariate. We investigated the implications of two potential range restriction scenarios: direct truncation on a selection measure and indirect range restriction on correlated measures. Empirical and simulated data indicated direct range restriction on the pretest covariate greatly reduced statistical power and necessitated sample size increases of 82%–155% (dependent on selection criteria) to achieve equivalent statistical power to parameters with unrestricted samples. However, measures demonstrating indirect range restriction required much smaller sample size increases (32%–71%) under equivalent scenarios. Additional analyses manipulated the correlations between measures and pretest-posttest correlations to guide planning experiments. Results highlight the need to differentiate between selection measures and potential covariates and to investigate range restriction as a factor impacting statistical power. PMID:28479943

Designing Intervention Studies: Selected Populations, Range Restrictions, and Statistical Power.

PubMed

Miciak, Jeremy; Taylor, W Pat; Stuebing, Karla K; Fletcher, Jack M; Vaughn, Sharon

2016-01-01

An appropriate estimate of statistical power is critical for the design of intervention studies. Although the inclusion of a pretest covariate in the test of the primary outcome can increase statistical power, samples selected on the basis of pretest performance may demonstrate range restriction on the selection measure and other correlated measures. This can result in attenuated pretest-posttest correlations, reducing the variance explained by the pretest covariate. We investigated the implications of two potential range restriction scenarios: direct truncation on a selection measure and indirect range restriction on correlated measures. Empirical and simulated data indicated direct range restriction on the pretest covariate greatly reduced statistical power and necessitated sample size increases of 82%-155% (dependent on selection criteria) to achieve equivalent statistical power to parameters with unrestricted samples. However, measures demonstrating indirect range restriction required much smaller sample size increases (32%-71%) under equivalent scenarios. Additional analyses manipulated the correlations between measures and pretest-posttest correlations to guide planning experiments. Results highlight the need to differentiate between selection measures and potential covariates and to investigate range restriction as a factor impacting statistical power.

The Development and Single-Laboratory Validation of a Method for the Determination of Steroid Residues in Fish and Fish Products.

PubMed

Watson, Lynn; Potter, Ross; Murphy, Cory; Gibbs, Ryan

2015-01-01

Due to potential use in aquacultured fish products, the Canadian Food Inspection Agency has identified residue testing for steroids as a priority. These compounds are used in aquaculture primarily to direct sexual differentiation with both androgens and estrogens applied depending on the desired outcome. Published research is lacking with respect to steroid residue testing in fish; however, recent studies in other matrixes provided transferable cleanup techniques. A simple, rapid, and sensitive method was developed and validated for use in monitoring aquacultured fish products for the presence of methyltestosterone, nandrolone, epi-nandrolone, boldenone, and epi-boldenone residues. The developed method consists of solvent extraction followed by cleanup using hexane and dual cartridge SPE with analysis by ultra-HPLC-MS/MS. The method is capable of detecting and confirming steroid residue levels ranging from 0.05 to 25 ng/g in salmon and tilapia, depending on the analyte. Recoveries ranged from 88 to 130% for the analytes. Instrument repeatability was less than 13% for all compounds, while intermediate precision ranged from 5 to 25% RSD. HorRat values were within acceptable ranges.

Doping Evolution of Magnetic Order and Magnetic Excitations in (Sr1 -xLax)3Ir2O7

NASA Astrophysics Data System (ADS)

Lu, Xingye; McNally, D. E.; Moretti Sala, M.; Terzic, J.; Upton, M. H.; Casa, D.; Ingold, G.; Cao, G.; Schmitt, T.

2017-01-01

We use resonant elastic and inelastic x-ray scattering at the Ir-L3 edge to study the doping-dependent magnetic order, magnetic excitations, and spin-orbit excitons in the electron-doped bilayer iridate (Sr1 -xLax )3Ir2 O7 (0 ≤x ≤0.065 ). With increasing doping x , the three-dimensional long range antiferromagnetic order is gradually suppressed and evolves into a three-dimensional short range order across the insulator-to-metal transition from x =0 to 0.05, followed by a transition to two-dimensional short range order between x =0.05 and 0.065. Because of the interactions between the Jeff=1/2 pseudospins and the emergent itinerant electrons, magnetic excitations undergo damping, anisotropic softening, and gap collapse, accompanied by weakly doping-dependent spin-orbit excitons. Therefore, we conclude that electron doping suppresses the magnetic anisotropy and interlayer couplings and drives (Sr1 -xLax )3Ir2 O7 into a correlated metallic state with two-dimensional short range antiferromagnetic order. Strong antiferromagnetic fluctuations of the Jeff=1/2 moments persist deep in this correlated metallic state, with the magnon gap strongly suppressed.

Measurement of angularly dependent spectra of betatron gamma-rays from a laser plasma accelerator with quadrant-sectored range filters

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

Jeon, Jong Ho, E-mail: jhjeon07@ibs.re.kr; Nakajima, Kazuhisa, E-mail: naka115@dia-net.ne.jp; Rhee, Yong Joo

Measurement of angularly dependent spectra of betatron gamma-rays radiated by GeV electron beams from laser wakefield accelerators (LWFAs) are presented. The angle-resolved spectrum of betatron radiation was deconvolved from the position dependent data measured for a single laser shot with a broadband gamma-ray spectrometer comprising four-quadrant sectored range filters and an unfolding algorithm, based on the Monte Carlo code GEANT4. The unfolded gamma-ray spectra in the photon energy range of 0.1–10 MeV revealed an approximately isotropic angular dependence of the peak photon energy and photon energy-integrated fluence. As expected by the analysis of betatron radiation from LWFAs, the results indicate thatmore » unpolarized gamma-rays are emitted by electrons undergoing betatron motion in isotropically distributed orbit planes.« less

An exploratory analysis of changes in mood, anxiety and craving from pre- to post-single sessions of exercise, over 12 weeks, among patients with alcohol dependence.

PubMed

Brown, Richard A; Prince, Mark A; Minami, Haruka; Abrantes, Ana M

2016-10-01

Aerobic exercise is currently being studied as a relapse prevention strategy for individuals with alcohol use disorders. Negative affect and cravings predict relapse. The acute effects of moderate-intensity exercise have been shown to improve mood and reduce craving. The current study examined the acute effects of exercise on changes in mood, anxiety, and craving from pre- to post-exercise at each week of a 12-week moderate intensity exercise intervention with sedentary alcohol dependent adults. Twenty-six participants in the exercise condition of a larger randomized clinical trial (Brown et al., 2014) exercised in small groups at moderate intensity for 20 to 40 minutes per session. Participants rated mood, anxiety, and cravings in the present moment before and after each exercise session over the course of the 12-week intervention. Data analyses focused on effect size and interval estimation. Joinpoint analysis was used to model longitudinal trends. Increases in mood and decreases in anxiety and craving were apparent at every session. Effect size estimates revealed that average change from pre- to post-exercise was in the small to medium range with some individual sessions reaching the large range. Joinpoint analyses revealed that the pre-post exercise changes in mood increased, anxiety remained stable, and craving diminished across the 12 weeks. This study provides provisional support for a change in mood, anxiety and alcohol cravings for the role of exercise in the early recovery period for alcohol dependence. Acute single bouts of moderate-intensity exercise may help individuals with alcohol dependence manage mood, anxiety, and craving thereby reducing relapse risk, but further research is needed with a more rigorous study design.

A swinging seesaw as a novel model mechanism for time-dependent hormesis under dose-dependent stimulatory and inhibitory effects: A case study on the toxicity of antibacterial chemicals to Aliivibrio fischeri.

PubMed

Sun, Haoyu; Calabrese, Edward J; Zheng, Min; Wang, Dali; Pan, Yongzheng; Lin, Zhifen; Liu, Ying

2018-08-01

Hormesis occurs frequently in broadly ranging biological areas (e.g. plant biology, microbiology, biogerontology), toxicology, pharmacology and medicine. While numerous mechanisms (e.g. receptor and pathway mediated pathway responses) account for stimulatory and inhibitory features of hormetic dose responses, the vast majority emphasizes the inclusion of many doses but only one timepoint or use of a single optimized dose that is assessed over a broad range of timepoints. In this paper, a toxicity study was designed using a large number of properly spaced doses with responses determined over a large number of timepoints, which could help us reveal the underlying mechanism of hormesis. We present the results of a dose-time-response study on hormesis using five antibacterial chemicals on the bioluminescence of Aliivibrio fischeri, measuring expression of protein mRNA based on quorum sensing, simulating bioluminescent reaction and analyzing toxic actions of test chemicals. The findings show dose-time-dependent responses conforming to the hormetic dose-response model, while revealing unique response dynamics between agent induced stimulatory and inhibitory effects within bacterial growth phase dynamics. These dynamic dose-time features reveal a type of biological seesaw model that integrates stimulatory and inhibitory responses within unique growth phase, dose and time features, which has faultlessly explained the time-dependent hormetic phenomenon induced by five antibacterial chemicals (characterized by low-dose stimulation and high-dose inhibition). This study offers advances in understanding cellular dynamics, the biological integration of diverse and opposing responses and their role in evolutionary adaptive strategies to chemicals, which can provide new insight into the mechanistic investigation of hormesis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Problematic Internet Use, Excessive Alcohol Consumption, Their Comorbidity and Cardiovascular and Cortisol Reactions to Acute Psychological Stress in a Student Population

PubMed Central

Bibbey, Adam; Phillips, Anna C.; Ginty, Annie T.; Carroll, Douglas

2015-01-01

Background and Aims Problematic Internet use and excessive alcohol consumption have been associated with a host of maladaptive outcomes. Further, low (blunted) cardiovascular and stress hormone (e.g. cortisol) reactions to acute psychological stress are a feature of individuals with a range of adverse health and behavioural characteristics, including dependencies such as tobacco and alcohol addiction. The present study extended this research by examining whether behavioural dependencies, namely problematic Internet use, excessive alcohol consumption, and their comorbidity would also be associated with blunted stress reactivity. Methods A large sample of university students (N = 2313) were screened using Internet and alcohol dependency questionnaires to select four groups for laboratory testing: comorbid Internet and alcohol dependence (N = 17), Internet dependence (N = 17), alcohol dependence (N = 28), and non-dependent controls (N = 26). Cardiovascular activity and salivary cortisol were measured at rest and in response to a psychological stress protocol comprising of mental arithmetic and public speaking tasks. Results Neither problematic Internet behaviour nor excessive alcohol consumption, either individually or in combination, were associated with blunted cardiovascular or cortisol stress reactions. Discussion It is possible that problematic Internet behaviour and excessive alcohol consumption in a student population were not related to physiological reactivity as they may not reflect ingrained addictions but rather an impulse control disorder and binging tendency. Conclusions The present results serve to indicate some of the limits of the developing hypothesis that blunted stress reactivity is a peripheral marker of the central motivational dysregulation in the brain underpinning a wide range of health and behavioural problems. PMID:26014670

Experimental Characterization of Stress- and Strain-Dependent Stiffness in Grouted Rock Masses.

PubMed

Kim, Ji-Won; Chong, Song-Hun; Cho, Gye-Chun

2018-03-29

Grouting of fractured rock mass prior to excavation results in grout-filled discontinuities that govern the deformation characteristics of a site. The influence of joint characteristics on the properties of grouted rocks is important in assessing the effects of grouting on jointed rock mass. However, grouting remains a predominantly empirical practice and the effects of grouting on rock joint behavior and material properties have yet to be accurately assessed. Granular materials, including jointed rocks, typically display nonlinear strain-dependent responses that can be characterized by the shear modulus degradation curve. In this study, the effects of grouting on the strain-dependent shear stiffness of jointed rock mass were investigated at the small-strain (below 10 -5 ) and mid-strain (10 -5 to 10 -3 ) ranges using the quasi-static resonant column test and rock mass dynamic test devices. The effects of curing time, axial stress, initial joint roughness, and grouted joint thickness were examined. The results show that (1) grouting of rock joints leads to decreased stress sensitivity and increased small-strain shear stiffness for all tested samples; (2) the grouted rock samples display similar modulus degradation characteristics as the applied grout material; (3) the initial joint roughness determines the stress-dependent behaviors and general stiffness range of the jointed and grouted rocks, but the strain-dependent behaviors are dependent on the properties of the grout material; (4) increased grouted joint thickness results in larger contribution of the grout properties in the overall grouted rock mass.

Experimental Characterization of Stress- and Strain-Dependent Stiffness in Grouted Rock Masses

PubMed Central

Cho, Gye-Chun

2018-01-01

Grouting of fractured rock mass prior to excavation results in grout-filled discontinuities that govern the deformation characteristics of a site. The influence of joint characteristics on the properties of grouted rocks is important in assessing the effects of grouting on jointed rock mass. However, grouting remains a predominantly empirical practice and the effects of grouting on rock joint behavior and material properties have yet to be accurately assessed. Granular materials, including jointed rocks, typically display nonlinear strain-dependent responses that can be characterized by the shear modulus degradation curve. In this study, the effects of grouting on the strain-dependent shear stiffness of jointed rock mass were investigated at the small-strain (below 10−5) and mid-strain (10−5 to 10−3) ranges using the quasi-static resonant column test and rock mass dynamic test devices. The effects of curing time, axial stress, initial joint roughness, and grouted joint thickness were examined. The results show that (1) grouting of rock joints leads to decreased stress sensitivity and increased small-strain shear stiffness for all tested samples; (2) the grouted rock samples display similar modulus degradation characteristics as the applied grout material; (3) the initial joint roughness determines the stress-dependent behaviors and general stiffness range of the jointed and grouted rocks, but the strain-dependent behaviors are dependent on the properties of the grout material; (4) increased grouted joint thickness results in larger contribution of the grout properties in the overall grouted rock mass. PMID:29596371

Impact of low cost refurbishable and standard spacecraft upon future NASA space programs. Payload effects follow-on study

NASA Technical Reports Server (NTRS)

1972-01-01

The study has concluded that there are very large space program cost savings to be obtained by use of low cost, refurbishable, and standard spacecraft in conjunction with the shuttle transportation system. The range of space program cost savings for three different groups of programs are shown in quantitative terms. The total savings for the 91 programs will range from $13.4 billion to $18.0 billion depending on the degree of hardware standardization. These savings, principally resulting from payload cost reductions, tangibly support the development costs of the shuttle system.

Feasibility of RACT for 3D dose measurement and range verification in a water phantom.

PubMed

Alsanea, Fahed; Moskvin, Vadim; Stantz, Keith M

2015-02-01

The objective of this study is to establish the feasibility of using radiation-induced acoustics to measure the range and Bragg peak dose from a pulsed proton beam. Simulation studies implementing a prototype scanner design based on computed tomographic methods were performed to investigate the sensitivity to proton range and integral dose. Derived from thermodynamic wave equation, the pressure signals generated from the dose deposited from a pulsed proton beam with a 1 cm lateral beam width and a range of 16, 20, and 27 cm in water using Monte Carlo methods were simulated. The resulting dosimetric images were reconstructed implementing a 3D filtered backprojection algorithm and the pressure signals acquired from a 71-transducer array with a cylindrical geometry (30 × 40 cm) rotated over 2π about its central axis. Dependencies on the detector bandwidth and proton beam pulse width were performed, after which, different noise levels were added to the detector signals (using 1 μs pulse width and a 0.5 MHz cutoff frequency/hydrophone) to investigate the statistical and systematic errors in the proton range (at 20 cm) and Bragg peak dose (of 1 cGy). The reconstructed radioacoustic computed tomographic image intensity was shown to be linearly correlated to the dose within the Bragg peak. And, based on noise dependent studies, a detector sensitivity of 38 mPa was necessary to determine the proton range to within 1.0 mm (full-width at half-maximum) (systematic error < 150 μm) for a 1 cGy Bragg peak dose, where the integral dose within the Bragg peak was measured to within 2%. For existing hydrophone detector sensitivities, a Bragg peak dose of 1.6 cGy is possible. This study demonstrates that computed tomographic scanner based on ionizing radiation-induced acoustics can be used to verify dose distribution and proton range with centi-Gray sensitivity. Realizing this technology into the clinic has the potential to significantly impact beam commissioning, treatment verification during particle beam therapy and image guided techniques.

Strain dependence of perfluorinated polymer optical fiber Bragg grating measured at different wavelengths

NASA Astrophysics Data System (ADS)

Ishikawa, Ryo; Lee, Heeyoung; Lacraz, Amédée; Theodosiou, Antreas; Kalli, Kyriacos; Mizuno, Yosuke; Nakamura, Kentaro

2018-03-01

We measure the strain dependence of multiple Bragg wavelengths (corresponding to different diffraction orders) of a fiber Bragg grating (FBG) inscribed in a perfluorinated graded-index polymer optical fiber (PFGI-POF) in the wavelength range up to 1550 nm. On the basis of this result, we show that the fractional sensitivity, which has been conventionally used as a wavelength-independent index for fair comparison of the FBG performance measured at different wavelengths, is dependent on wavelength in this range. The reason for this behavior seems to originate from the non-negligible wavelength dependence of refractive index and its strain-dependence coefficient. Using the wavelength dependence of the refractive index already reported for bulk, we deduce the wavelength dependence of the strain coefficient of the refractive index. This information will be a useful archive in implementing PFGI-POF-based strain sensors based on not only FBGs but also Brillouin scattering in the future.

Speed-dependent Voigt lineshape parameter database from dual frequency comb measurements up to 1305 K. Part I: Pure H2O absorption, 6801-7188 cm-1

NASA Astrophysics Data System (ADS)

Schroeder, Paul J.; Cich, Matthew J.; Yang, Jinyu; Giorgetta, Fabrizio R.; Swann, William C.; Coddington, Ian; Newbury, Nathan R.; Drouin, Brian J.; Rieker, Gregory B.

2018-05-01

We measure speed-dependent Voigt lineshape parameters with temperature-dependence exponents for several hundred spectroscopic features of pure water spanning 6801-7188 cm-1. The parameters are extracted from broad bandwidth, high-resolution dual frequency comb absorption spectra with multispectrum fitting techniques. The data encompass 25 spectra ranging from 296 K to 1305 K and 1 to 17 Torr of pure water vapor. We present the extracted parameters, compare them to published data, and present speed-dependence, self-shift, and self-broadening temperature-dependent parameters for the first time. Lineshape data is extracted using a quadratic speed-dependent Voigt profile and a single self-broadening power law temperature-dependence exponent over the entire temperature range. The results represent an important step toward a new high-temperature database using advanced lineshape profiles.

Determination of Henry’s Law Constants Using Internal Standards with Benchmark Values

EPA Science Inventory

It is shown that Henry’s law constants can be experimentally determined by comparing headspace content of compounds with known constants to interpolate the constants of other compounds. Studies were conducted over a range of water temperatures to identify temperature dependence....

Leakage current transport mechanism under reverse bias in Au/Ni/GaN Schottky barrier diode

NASA Astrophysics Data System (ADS)

Peta, Koteswara Rao; Kim, Moon Deock

2018-01-01

The leakage current transport mechanism under reverse bias of Au/Ni/GaN Schottky diode is studied using temperature dependent current-voltage (I-V-T) and capacitance-voltage (C-V) characteristics. I-V measurement in this study is in the range of 140 K-420 K in steps of 10 K. A reduction in voltage dependent barrier height and a strong internal electric field in depletion region under reverse bias suggested electric field enhanced thermionic emission in carrier transport via defect states in Au/Ni/GaN SBD. A detailed analysis of reverse leakage current revealed two different predominant transport mechanisms namely variable-range hopping (VRH) and Poole-Frenkel (PF) emission conduction at low (<260 K) and high (>260 K) temperatures respectively. The estimated thermal activation energies (0.20-0.39 eV) from Arrhenius plot indicates a trap assisted tunneling of thermally activated electrons from a deep trap state into a continuum of states associated with each conductive threading dislocation.

Isospin effects on the system mass dependence of nuclear stopping around the energy of vanishing flow

NASA Astrophysics Data System (ADS)

Jain, Anupriya; Kumar, Suneel

2014-10-01

We study the effect of isospin degree of freedom on nuclear stopping throughout the mass range 50 and 350 for two sets of isotopic systems with N/Z ≈ 1.5 and 1.8, as well as isobaric systems with N/Z = 1.0 and 1.4. Analysis is carried out at incident energies below, at, and above the energy of vanishing flow (EVF) using the isospin-dependent quantum molecular dynamics model. Our findings reveal that nuclear stopping does not show any particular behavior at the EVF. Moreover, system size effects dominate the isospin effects throughout the range of colliding geometry. The Coulomb effects, however, become important at peripheral geometry. The comparative study of the counterbalancing of Coulomb and mean field by removing the nucleon-nucleon collisions and symmetry potential clearly indicates the dominance of nucleon-nucleon cross-section over the Coulomb repulsions. Moreover, the theoretical results presented in this manuscript for the set of reactions can be experimentally verified.

Temperature and baric dependence of nuclear quadruple resonance spectra in indium and gallium monoselenides

NASA Astrophysics Data System (ADS)

Khandozhko, Victor; Raranskii, Nikolai; Balazjuk, Vitaly; Samila, Andriy; Kovalyuk, Zahar

2013-12-01

Pulsed radiospectroscopy method has been used to study nuclear quadruple resonance (NQR) spectra of 69Ga and 115In isotopes in the layered semiconductors GaSe and InSe. It has been found that in GaSe and InSe there is a considerable temperature dependence of NQR frequency which in the temperature range of 250 to 390 K is practically linear with conversion slope 1.54 kHz/degree for 69Ga and 2.35 kHz/degree for 115In. In the same crystals the effect of uniaxial pressure on NQR spectra applied along the optical axis с up to the values of 500 kg/сm2 has been studied. A strong attenuation of NQR spectra intensity with increase in pressure on layered crystal package has been established. The unvaried multiplicity of resonance spectra indicates the absence of structural transformations in these layered crystals over the investigated range of temperatures and pressures.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Study of photodissociation parameters of carboxyhemoglobin

NASA Astrophysics Data System (ADS)

Kuz'min, V. V.; Salmin, V. V.; Salmina, A. B.; Provorov, A. S.

2008-07-01

The general properties of photodissociation of carboxyhemoglobin (HbCO) in buffer solutions of whole human blood are studied by the flash photolysis method on a setup with intersecting beams. It is shown that the efficiency of photoinduced dissociation of the HbCO complex virtually linearly depends on the photolytic irradiation intensity for the average power density not exceeding 45 mW cm-2. The general dissociation of the HbCO complex in native conditions occurs in a narrower range of values of the saturation degree than in model experiments with the hemoglobin solution. The dependence of the pulse photolysis efficiency of HbCO on the photolytic radiation wavelength in the range from 550 to 585 nm has a broad bell shape. The efficiency maximum corresponds to the electronic Q transition (porphyrin π—π* absorption) in HbCO at a wavelength of 570 nm. No dissociation of the complex was observed under given experimental conditions upon irradiation of solutions by photolytic radiation at wavelengths above 585 nm.

Temperature-dependent vibrational spectroscopy to study order-disorder transitions in charge transfer complexes

NASA Astrophysics Data System (ADS)

Isaac, Rohan; Goetz, Katelyn P.; Roberts, Drew; Jurchescu, Oana D.; McNeil, L. E.

2018-02-01

Charge-transfer (CT) complexes are a promising class of materials for the semiconductor industry because of their versatile properties. This class of compounds shows a variety of phase transitions, which are of interest because of their potential impact on the electronic characteristics. Here temperature-dependent vibrational spectroscopy is used to study structural phase transitions in a set of organic CT complexes. Splitting and broadening of infrared-active phonons in the complex formed between pyrene and pyromellitic dianhydride (PMDA) confirm the structural transition is of the order-disorder type and complement previous x-ray diffraction (XRD) results. We show that this technique is a powerful tool to characterize transitions, and apply it to a range of binary CT complexes composed of polyaromatic hyrdocarbons (anthracene, perylene, phenanthrene, pyrene, and stilbene) and PMDA. We extend the understanding of transitions in perylene-PMDA and pyrene-PMDA, and show that there are no order-disorder transitions present in anthracene-PMDA, stilbene-PMDA and phenanthrene-PMDA in the temperature range investigated here.

The rate dependent response of a bistable chain at finite temperature

NASA Astrophysics Data System (ADS)

Benichou, Itamar; Zhang, Yaojun; Dudko, Olga K.; Givli, Sefi

2016-10-01

We study the rate dependent response of a bistable chain subjected to thermal fluctuations. The study is motivated by the fact that the behavior of this model system is prototypical to a wide range of nonlinear processes in materials physics, biology and chemistry. To account for the stochastic nature of the system response, we formulate a set of governing equations for the evolution of the probability density of meta-stable configurations. Based on this approach, we calculate the behavior for a wide range of parametric values, such as rate, temperature, overall stiffness, and number of elements in the chain. Our results suggest that fundamental characteristics of the response, such as average transition stress and hysteresis, can be captured by a simple law which folds the influence of all these factors into a single non-dimensional quantity. We also show that the applicability of analytical results previously obtained for single-well systems can be extended to systems having multiple wells by proper definition of rate and of the transition stress.

Winter Precipitation Efficiency of Mountain Ranges in the Colorado Rockies Under Climate Change

NASA Astrophysics Data System (ADS)

Eidhammer, Trude; Grubišić, Vanda; Rasmussen, Roy; Ikdea, Kyoko

2018-03-01

Orographic precipitation depends on the environmental conditions and the barrier shape. In this study we examine the sensitivity of the precipitation efficiency (i.e., drying ratio (DR)), defined as the ratio of precipitation to incoming water flux, to mountain shape, temperature, stability, and horizontal velocity of the incoming air mass. Furthermore, we explore how the DR of Colorado mountain ranges might change under warmer and moister conditions in the future. For given environmental conditions, we find the DR to be primarily dependent on the upwind slope for mountain ranges wider than about 70 km and on both the slope and width for narrower ranges. Temperature is found to exert an influence on the DR for all Colorado mountain ranges, with DR decreasing with increasing temperature, under both the current and future climate conditions. The decrease of DR with temperature under warmer climate was found to be stronger for wider mountains than the narrower ones. We attribute this asymmetry to the sensitivity of DR to reduced horizontal velocity under warmer conditions. Specifically, while DR for wider mountains shows no sensitivity to changes in horizontal velocity, the DR for narrow ranges increases as the horizontal velocity decreases and more time is provided for precipitation to form. Thus, for narrower ranges, the horizontal velocity appears to offset the temperature effect slightly. The percentagewise decrease of DR for all examined mountain ranges is about 4%K-1. In comparison, the increase in precipitation is about 6%K-1 while the vapor flux increase is about 9%K-1.

Robustness and Vulnerability of Networks with Dynamical Dependency Groups.

PubMed

Bai, Ya-Nan; Huang, Ning; Wang, Lei; Wu, Zhi-Xi

2016-11-28

The dependency property and self-recovery of failure nodes both have great effects on the robustness of networks during the cascading process. Existing investigations focused mainly on the failure mechanism of static dependency groups without considering the time-dependency of interdependent nodes and the recovery mechanism in reality. In this study, we present an evolving network model consisting of failure mechanisms and a recovery mechanism to explore network robustness, where the dependency relations among nodes vary over time. Based on generating function techniques, we provide an analytical framework for random networks with arbitrary degree distribution. In particular, we theoretically find that an abrupt percolation transition exists corresponding to the dynamical dependency groups for a wide range of topologies after initial random removal. Moreover, when the abrupt transition point is above the failure threshold of dependency groups, the evolving network with the larger dependency groups is more vulnerable; when below it, the larger dependency groups make the network more robust. Numerical simulations employing the Erdős-Rényi network and Barabási-Albert scale free network are performed to validate our theoretical results.

The role of age, gender, mood states and exercise frequency on exercise dependence.

PubMed

Costa, Sebastiano; Hausenblas, Heather A; Oliva, Patrizia; Cuzzocrea, Francesca; Larcan, Rosalba

2013-12-01

The purpose of our study was to explore the prevalence, and the role of mood, exercise frequency, age, and gender differences of exercise dependence. Regular exercisers (N = 409) completed a socio-demographic questionnaire, the Exercise Dependence Scale, and the Profile of Mood States. For data analyses, the participants were stratified for sex and age (age ranges = young adults: 18-24 years, adults: 25-44 years, and middle-aged adults: 45-64 years). We found that: (a) 4.4% of the participants were classified as at-risk for exercise dependence; (b) the men and the two younger groups (i.e., young adults and adults) had higher exercise dependence scores; and (c) age, gender, exercise frequency, and mood state were related to exercise dependence. Our results support previous research on the prevalence of exercise dependence and reveal that adulthood may be the critical age for developing exercise dependence. These findings have practical implication for identifying individuals at-risk for exercise dependence symptoms, and may aid in targeting and guiding the implementation of prevention program for adults.

A model-free characterization of recurrences in stationary time series

NASA Astrophysics Data System (ADS)

Chicheportiche, Rémy; Chakraborti, Anirban

2017-05-01

Study of recurrences in earthquakes, climate, financial time-series, etc. is crucial to better forecast disasters and limit their consequences. Most of the previous phenomenological studies of recurrences have involved only a long-ranged autocorrelation function, and ignored the multi-scaling properties induced by potential higher order dependencies. We argue that copulas is a natural model-free framework to study non-linear dependencies in time series and related concepts like recurrences. Consequently, we arrive at the facts that (i) non-linear dependences do impact both the statistics and dynamics of recurrence times, and (ii) the scaling arguments for the unconditional distribution may not be applicable. Hence, fitting and/or simulating the intertemporal distribution of recurrence intervals is very much system specific, and cannot actually benefit from universal features, in contrast to the previous claims. This has important implications in epilepsy prognosis and financial risk management applications.

Shape-dependence of the thermal and photochemical reactions of methanol on nanocrystalline anatase TiO2

NASA Astrophysics Data System (ADS)

Bennett, David A.; Cargnello, Matteo; Diroll, Benjamin T.; Murray, Christopher B.; Vohs, John M.

2016-12-01

Structure-activity relationships and the influence of particle size and shape on the partial- and photo-oxidation of methanol on nanocrystalline anatase TiO2 were investigated using temperature-programmed desorption. The study employed two distinct nanoparticle morphologies: truncated bipyramids exposing primarily {101} facets, and flatter platelets exposing primarily {001} surfaces, whose nominal sizes ranged from 10 to 25 nm. The platelets were found to be more active for thermally-driven reactions, such as coupling of methoxide groups to produce dimethyl ether, and deoxygenation to produce methane. A dependence of the reactivity of {001} facets for the coupling of methoxide groups to produce dimethyl ether on facet size was also observed. In contrast to the thermally-driven reactions, the bipyramidal nanoparticles were observed to be more active for a range of photochemical reactions, including oxidation and coupling to produce methyl formate, and photo-decomposition of surface methoxide species. This study also shows how well-defined nanocrystals can be used to help bridge the materials gap between studies of single crystal model catalysts and their high surface area industrial analogs.

Cl(-) concentration dependence of photovoltage generation by halorhodopsin from Halobacterium salinarum.

PubMed Central

Muneyuki, Eiro; Shibazaki, Chie; Wada, Yoichiro; Yakushizin, Manabu; Ohtani, Hiroyuki

2002-01-01

The photovoltage generation by halorhodopsin from Halobacterium salinarum (shR) was examined by adsorbing shR-containing membranes onto a thin polymer film. The photovoltage consisted of two major components: one with a sub-millisecond range time constant and the other with a millisecond range time constant with different amplitudes, as previously reported. These components exhibited different Cl(-) concentration dependencies (0.1-9 M). We found that the time constant for the fast component was relatively independent of the Cl(-) concentration, whereas the time constant for the slow component increased sigmoidally at higher Cl(-) concentrations. The fast and the slow processes were attributed to charge (Cl(-)) movements within the protein and related to Cl(-) ejection, respectively. The laser photolysis studies of shR-membrane suspensions revealed that they corresponded to the formation and the decay of the N intermediate. The photovoltage amplitude of the slow component exhibited a distorted bell-shaped Cl(-) concentration dependence, and the Cl(-) concentration dependence of its time constant suggested a weak and highly cooperative Cl(-)-binding site(s) on the cytoplasmic side (apparent K(D) of approximately 5 M and Hill coefficient > or =5). The Cl(-) concentration dependence of the photovoltage amplitude and the time constant for the slow process suggested a competition between spontaneous relaxation and ion translocation. The time constant for the relaxation was estimated to be >100 ms. PMID:12324398

Exploitation of the UV Aerosol Index scattering angle dependence: Properties of Siberian smoke plumes

NASA Astrophysics Data System (ADS)

Penning de Vries, Marloes; Beirle, Steffen; Sihler, Holger; Wagner, Thomas

2017-04-01

The UV Aerosol Index (UVAI) is a simple measure of aerosols from satellite that is particularly sensitive to elevated layers of absorbing particles. It has been determined from a range of instruments including TOMS, GOME-2, and OMI, for almost four decades and will be continued in the upcoming Sentinel missions S5-precursor, S4, and S5. Despite its apparent simplicity, the interpretation of UVAI is not straightforward, as it depends on aerosol abundance, absorption, and altitude in a non-linear way. In addition, UVAI depends on the geometry of the measurement (viewing angle, solar zenith and relative azimuth angles), particularly if viewing angles exceed 45 degrees, as is the case for OMI and TROPOMI (on S5-precursor). The dependence on scattering angle complicates the interpretation and further processing (e.g., averaging) of UVAI. In certain favorable cases, however, independent information on aerosol altitude and absorption may become available. We present a detailed study of the scatter angle dependence using SCIATRAN radiative transfer calculations. The model results were compared to observations of an extensive Siberian smoke plume, of which parts reached 10-12 km altitude. Due to its large extent and the high latitude, OMI observed the complete plume in five consecutive orbits under a wide range of scattering angles. This allowed us to deduce aerosol characteristics (absorption and layer height) that were compared with collocated CALIOP lidar measurements.

Temperature-Dependent Adhesion of Graphene Suspended on a Trench

PubMed Central

2015-01-01

Graphene deposited over a trench has been studied in the context of nanomechanical resonators, where experiments indicate adhesion of the graphene sheet to the trench boundary and sidewalls leads to self-tensioning; however, this adhesion is not well understood. We use molecular dynamics to simulate graphene deposited on a trench and study how adhesion to the sidewalls depends on substrate interaction, temperature, and curvature of the edge of the trench. Over the range of parameters we study, the depth at the center of the sheet is approximately linear in substrate interaction strength and temperature but not trench width, and we explain this using a one-dimensional model for the sheet configuration. PMID:26652939

The thermal conductivity of 1-chloro-1,1-difluoroethane (HCFC-142b)

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

Sousa, A.T.; Fialho, P.S.; Nieto de Castro, C.A.

1992-05-01

The thermal conductivity of 1-chloro-1,1-difluoroethane (HCFC-142b) has been measured in the temperature range 290 to 504 K and pressures up to 20 MPa with a concentric-cylinder apparatus operating in a steady-state mode. These temperature and pressure ranges cover all fluid states. The estimated accuracy of the method is about 2%. The density dependence of the thermal conductivity has been studied in the liquid region. 19 refs., 5 figs., 4 tabs.

Thresholds of physical activity associated with obesity by level of sedentary behaviour in children.

PubMed

Chaput, J-P; Barnes, J D; Tremblay, M S; Fogelholm, M; Hu, G; Lambert, E V; Maher, C; Maia, J; Olds, T; Onywera, V; Sarmiento, O L; Standage, M; Tudor-Locke, C; Katzmarzyk, P T

2018-03-24

It is unknown whether moderate-to-vigorous physical activity (MVPA) thresholds for obesity should be adapted depending on level of sedentary behaviour in children. The objective of the study is to determine the MVPA thresholds that best discriminate between obese and non-obese children, by level of screen time and total sedentary time in 12 countries. This multinational, cross-sectional study included 6522 children 9-11 years of age. MVPA and sedentary time were assessed using waist-worn accelerometry, while screen time was self-reported. Obesity was defined according to the World Health Organization reference data. Receiver operating characteristic curve analyses showed that the best thresholds of MVPA to predict obesity ranged from 53.8 to 73.9 min d -1 in boys and from 41.7 to 58.7 min d -1 in girls, depending on the level of screen time. The MVPA cut-offs to predict obesity ranged from 37.9 to 75.9 min d -1 in boys and from 32.5 to 62.7 min d -1 in girls, depending on the level of sedentary behaviour. The areas under the curve ranged from 0.57 to 0.73 ('fail' to 'fair' accuracy), and most sensitivity and specificity values were below 85%, similar to MVPA alone. Country-specific analyses provided similar findings. The addition of sedentary behaviour levels to MVPA did not result in a better predictive ability to classify children as obese/non-obese compared with MVPA alone. © 2018 World Obesity Federation.

Absorption and fluorescence spectra of heterocyclic isomers from long-range-corrected density functional theory in polarizable continuum approach.

PubMed

Kityk, Andriy V

2012-03-22

Long-range-corrected (LC) DFT/TDDFT methods may provide adequate description of ground and excited state properties; however, accuracy of such an approach depends much on a range separation (exchange screening) representing adjustable model parameter. Its relation to a size or specific of molecular systems has been explored in numerous studies, whereas the effect of solvent environment is usually ignored during the evaluation of state properties. To benchmark and assess the quality of the LC-DFT/TDDFT formalism, we report the optical absorption and fluorescence emission energies of organic heterocyclic isomers, DPIPQ and PTNA, calculated by LC-BLYP DFT/TDDFT method in the polarizable continuum (PCM) approach. The calculations are compared with the optical absorption and fluorescence spectra measured in organic solvents of different polarity. Despite a considerable structural difference, both dyes exhibit quite similar range separations being somewhat different for the optical absorption and fluorescence emission processes. Properly parametrized LC-BLYP xc-potential well reproduces basic features of the optical absorption spectra including the electronic transitions to higher excited states. The DFT/TDDFT/PCM analysis correctly predicts the solvation trends although solvatochromic shifts of the electronic transition energies appear to be evidently underestimated in most cases, especially for the fluorescence emission. Considering the discrepancy between the experiment and theory, evaluated state dipole moments and solvation corrections to the exchange screening are analyzed. The results of the present study emphasize the importance of a solvent-dependent range separation in DFT/TDDFT/PCM calculations for investigating excited state properties. © 2012 American Chemical Society

[Effect of glycine and strychnine on Cl(-)-activated Mg2+-ATPase from bream brain microsomes (Abamis brama L.)].

PubMed

Menzikov, S A; Menzikova, O V

2001-01-01

The effect of glycine and strychnine on Mg2+-ATPase from the microsomal fraction of the bream (Abramis brama L.) brain was studied. The glycine in the concentration range 10(-7)-10(-4) M activates the enzyme. The effect of glycine on Mg2+-ATPase is obviated by 100 microM strychnine. The strychnine in the concentration range 5-90 microM activates the basal Mg2+-ATPase but decreases the effect of the enzyme activation by 10(-4) M glycine. The effect of Cl- on Mg2+-ATPase depends on the substrate concentration (Mg2+-ATP) and is not observed in the presence of 100 microM strychnine. A receptor-dependent pathway of glycine and strychnine action on Cl(-)-activated Mg2+-ATPase from bream brain microsomes is proposed.

Frequency-dependent ultrasound-induced transformation in E. coli.

PubMed

Deeks, Jeremy; Windmill, James; Agbeze-Onuma, Maduka; Kalin, Robert M; Argondizza, Peter; Knapp, Charles W

2014-12-01

Ultrasound-enhanced gene transfer (UEGT) is continuing to gain interest across many disciplines; however, very few studies investigate UEGT efficiency across a range of frequencies. Using a variable frequency generator, UEGT was tested in E. coli at six ultrasonic frequencies. Results indicate frequency can significantly influence UEGT efficiency positively and negatively. A frequency of 61 kHz improved UEGT efficiency by ~70 % higher, but 99 kHz impeded UEGT to an extent worse than no ultrasound exposure. The other four frequencies (26, 133, 174, and 190 kHz) enhanced transformation compared to no ultrasound, but efficiencies did not vary. The influence of frequency on UEGT efficiency was observed across a range of operating frequencies. It is plausible that frequency-dependent dynamics of mechanical and chemical energies released during cavitational-bubble collapse (CBC) are responsible for observed UEGT efficiencies.

The diffusivity and solubility of deuterium in a high chromium martensitic steel

NASA Astrophysics Data System (ADS)

Forcey, K. S.; Iordanova, I.; Yaneva, M.

1997-01-01

The permeability, diffusivity and solubility of deuterium in the martensitic stainless steel MANET II have been studied in the temperature range 194-465°C by applying a time dependent gas-phase permeation technique. It was found that the temperature dependence of diffusivity and solubility could not be described by a simple Arrhenius expression over the entire temperature range investigated. At lower temperatures (below about 330°C) the diffusivity was found to be greatly reduced by the effects of trapping. Oriani's model has been applied to obtain the trapping energy and number density of the traps as well as the relative amounts of deuterium dissolved at lattice and trap sites. It is suggested that the most likely sites for trapping are at interfaces between the martensitic laths and between second phase particles and the surrounding metal matrix.

Time-dependent Second Order Scattering Theory for Weather Radar with a Finite Beam Width

NASA Technical Reports Server (NTRS)

Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood; Ito, Shigeo; Oguchi, Tomohiro

2006-01-01

Multiple scattering effects from spherical water particles of uniform diameter are studied for a W-band pulsed radar. The Gaussian transverse beam-profile and the rectangular pulse-duration are used for calculation. An second-order analytical solution is derived for a single layer structure, based on a time-dependent radiative transfer theory as described in the authors' companion paper. When the range resolution is fixed, increase in footprint radius leads to increase in the second order reflectivity that is defined as the ratio of the second order return to the first order one. This feature becomes more serious as the range increases. Since the spaceborne millimeter-wavelength radar has a large footprint radius that is competitive to the mean free path, the multiple scattering effect must be taken into account for analysis.

Path loss modeling and performance trade-off study for short-range non-line-of-sight ultraviolet communications.

PubMed

Chen, Gang; Xu, Zhengyuan; Ding, Haipeng; Sadler, Brian

2009-03-02

We consider outdoor non-line-of-sight deep ultraviolet (UV) solar blind communications at ranges up to 100 m, with different transmitter and receiver geometries. We propose an empirical channel path loss model, and fit the model based on extensive measurements. We observe range-dependent power decay with a power exponent that varies from 0.4 to 2.4 with varying geometry. We compare with the single scattering model, and show that the single scattering assumption leads to a model that is not accurate for small apex angles. Our model is then used to study fundamental communication system performance trade-offs among transmitted optical power, range, link geometry, data rate, and bit error rate. Both weak and strong solar background radiation scenarios are considered to bound detection performance. These results provide guidelines to system design.

The Dependence of the Spring Constant in the Linear Range on Spring Parameters

ERIC Educational Resources Information Center

Khotimah, Siti Nurul; Viridi, Sparisoma; Widayani; Khairurrijal

2011-01-01

In basic physics laboratories, springs are normally used to determine both spring constants and the Earth's gravitational acceleration. Students generally do not notice that the spring constant is not a universal constant, but depends on the spring parameters. This paper shows and verifies that the spring constant in the linear range is inversely…

Natural course of care dependency in residents of long-term care facilities: prospective follow-up study

PubMed Central

2014-01-01

Background Insight in the natural course of care dependency of vulnerable older persons in long-term care facilities (LTCF) is essential to organize and optimize individual tailored care. We examined changes in care dependency in LTCF residents over two 6-month periods, explored the possible predictive factors of change and the effect of care dependency on mortality. Methods A prospective follow-up study in 21 Dutch long-term care facilities. 890 LTCF residents, median age 84 (Interquartile range 79–88) years participated. At baseline, 6 and 12 months, care dependency was assessed by the nursing staff with the Care Dependency Scale (CDS), range 15–75 points. Since the median CDS score differed between men and women (47.5 vs. 43.0, P = 0.013), CDS groups (low, middle and high) were based on gender-specific 33% of CDS scores at baseline and 6 months. Results At baseline, the CDS groups differed in median length of stay on the ward, urine incontinence and dementia (all P < 0.001); participants in the low CDS group stayed longer, had more frequent urine incontinence and more dementia. They had also the highest mortality rate (log rank 32.2; df = 2; P for trend <0.001). Per point lower in CDS score, the mortality risk increased with 2% (95% CI 1%-3%). Adjustment for age, gender, cranberry use, LTCF, length of stay, comorbidity and dementia showed similar results. A one point decrease in CDS score between 0 and 6 months was related to an increased mortality risk of 4% (95% CI 3%-6%). At the 6-month follow-up, 10% improved to a higher CDS group, 65% were in the same, and 25% had deteriorated to a lower CDS group; a similar pattern emerged at 12-month follow-up. Gender, age, urine incontinence, dementia, cancer and baseline care dependency status, predicted an increase in care dependency over time. Conclusion The majority of residents were stable in their care dependency status over two subsequent 6-month periods. Highly care dependent residents showed an increased mortality risk. Awareness of the natural course of care dependency is essential to residents and their formal and informal caregivers when considering therapeutic and end-of-life care options. PMID:24884563

Natural course of care dependency in residents of long-term care facilities: prospective follow-up study.

PubMed

Caljouw, Monique A A; Cools, Herman J M; Gussekloo, Jacobijn

2014-05-22

Insight in the natural course of care dependency of vulnerable older persons in long-term care facilities (LTCF) is essential to organize and optimize individual tailored care. We examined changes in care dependency in LTCF residents over two 6-month periods, explored the possible predictive factors of change and the effect of care dependency on mortality. A prospective follow-up study in 21 Dutch long-term care facilities. 890 LTCF residents, median age 84 (Interquartile range 79-88) years participated. At baseline, 6 and 12 months, care dependency was assessed by the nursing staff with the Care Dependency Scale (CDS), range 15-75 points. Since the median CDS score differed between men and women (47.5 vs. 43.0, P = 0.013), CDS groups (low, middle and high) were based on gender-specific 33% of CDS scores at baseline and 6 months. At baseline, the CDS groups differed in median length of stay on the ward, urine incontinence and dementia (all P < 0.001); participants in the low CDS group stayed longer, had more frequent urine incontinence and more dementia. They had also the highest mortality rate (log rank 32.2; df = 2; P for trend <0.001). Per point lower in CDS score, the mortality risk increased with 2% (95% CI 1%-3%). Adjustment for age, gender, cranberry use, LTCF, length of stay, comorbidity and dementia showed similar results. A one point decrease in CDS score between 0 and 6 months was related to an increased mortality risk of 4% (95% CI 3%-6%).At the 6-month follow-up, 10% improved to a higher CDS group, 65% were in the same, and 25% had deteriorated to a lower CDS group; a similar pattern emerged at 12-month follow-up. Gender, age, urine incontinence, dementia, cancer and baseline care dependency status, predicted an increase in care dependency over time. The majority of residents were stable in their care dependency status over two subsequent 6-month periods. Highly care dependent residents showed an increased mortality risk. Awareness of the natural course of care dependency is essential to residents and their formal and informal caregivers when considering therapeutic and end-of-life care options.

Attachment Styles and Suicide-Related Behaviors in Adolescence: The Mediating Role of Self-Criticism and Dependency

PubMed Central

Falgares, Giorgio; Marchetti, Daniela; De Santis, Sandro; Carrozzino, Danilo; Kopala-Sibley, Daniel C.; Fulcheri, Mario; Verrocchio, Maria Cristina

2017-01-01

Insecure attachment and the personality dimensions of self-criticism and dependency have been proposed as risk factors for suicide in adolescents. The present study examines whether self-criticism and dependency mediate the relationship between insecure attachment styles and suicidality. A sample of 340 high-school students (73.2% females), ranging in age from 13 to 20 years (M = 16.47, SD = 1.52), completed the Depressive Experiences Questionnaire for Adolescents, the Depressive Experiences Questionnaire for Adolescents, the Attachment Style Questionnaire, and the Suicidal Behaviors Questionnaire-Revised. The results partially support the expected mediation effects. Self-criticism, but not dependency, mediates the link between insecure attachment (anxiety and avoidance) and suicide-related behaviors. Implications for suicide risk assessment and management are discussed. PMID:28344562

Dynamic blocked transfer stiffness method of characterizing the magnetic field and frequency dependent dynamic viscoelastic properties of MRE

NASA Astrophysics Data System (ADS)

Poojary, Umanath R.; Hegde, Sriharsha; Gangadharan, K. V.

2016-11-01

Magneto rheological elastomer (MRE) is a potential resilient element for the semi active vibration isolator. MRE based isolators adapt to different frequency of vibrations arising from the source to isolate the structure over wider frequency range. The performance of MRE isolator depends on the magnetic field and frequency dependent characteristics of MRE. Present study is focused on experimentally evaluating the dynamic stiffness and loss factor of MRE through dynamic blocked transfer stiffness method. The dynamic stiffness variations of MRE exhibit strong magnetic field and mild frequency dependency. Enhancements in dynamic stiffness saturate with the increase in magnetic field and the frequency. The inconsistent variations of loss factor with the magnetic field substantiate the inability of MRE to have independent control over its damping characteristics.

Founder takes all: density-dependent processes structure biodiversity.

PubMed

Waters, Jonathan M; Fraser, Ceridwen I; Hewitt, Godfrey M

2013-02-01

Density-dependent processes play a key role in the spatial structuring of biodiversity. Specifically, interrelated demographic processes, such as gene surfing, high-density blocking, and competitive exclusion, can generate striking geographic contrasts in the distributions of genes and species. Here, we propose that well-studied evolutionary and ecological biogeographic patterns of postglacial recolonization, progressive island colonization, microbial sectoring, and even the 'Out of Africa' pattern of human expansion, are fundamentally similar, underpinned by a 'founder takes all' density-dependent principle. Additionally, we hypothesize that older historic constraints of density-dependent processes are seen today in the dramatic biogeographic shifts that occur in response to human-mediated extinction events, whereby surviving lineages rapidly expand their ranges to replace extinct sister taxa. Copyright © 2012 Elsevier Ltd. All rights reserved.

Experience-dependent enhancement of pitch-specific responses in the auditory cortex is limited to acceleration rates in normal voice range

PubMed Central

Krishnan, Ananthanarayan; Gandour, Jackson T.; Suresh, Chandan H.

2015-01-01

The aim of this study is to determine how pitch acceleration rates within and outside the normal pitch range may influence latency and amplitude of cortical pitch-specific responses (CPR) as a function of language experience (Chinese, English). Responses were elicited from a set of four pitch stimuli chosen to represent a range of acceleration rates (two each inside and outside the normal voice range) imposed on the high rising Mandarin Tone 2. Pitch-relevant neural activity, as reflected in the latency and amplitude of scalp-recorded CPR components, varied depending on language-experience and pitch acceleration of dynamic, time-varying pitch contours. Peak latencies of CPR components were shorter in the Chinese than the English group across stimuli. Chinese participants showed greater amplitude than English for CPR components at both frontocentral and temporal electrode sites in response to pitch contours with acceleration rates inside the normal voice pitch range as compared to pitch contours with acceleration rates that exceed the normal range. As indexed by CPR amplitude at the temporal sites, a rightward asymmetry was observed for the Chinese group only. Only over the right temporal site was amplitude greater in the Chinese group relative to the English. These findings may suggest that the neural mechanism(s) underlying processing of pitch in the right auditory cortex reflect experience-dependent modulation of sensitivity to acceleration in just those rising pitch contours that fall within the bounds of one’s native language. More broadly, enhancement of native pitch stimuli and stronger rightward asymmetry of CPR components in the Chinese group is consistent with the notion that long-term experience shapes adaptive, distributed hierarchical pitch processing in the auditory cortex, and reflects an interaction with higher-order, extrasensory processes beyond the sensory memory trace. PMID:26166727

Wavelength dependent recovery of UV-mediated damage: Tying up the loose ends of optical based powdery mildew management.

PubMed

Suthaparan, Aruppillai; Pathak, Ranjana; Solhaug, Knut Asbjørn; Gislerød, Hans Ragnar

2018-01-01

Controlled environment chamber experiments at Petri dish level were conducted to examine the wavelength and dose dependent efficacy of ultraviolet (UV) radiation, the recovery action potential of optical radiation applied concomitantly/subsequently to effective UV treatment, and the lapse time between UV treatment and subsequent exposure to recovery wavelength on germination efficiency of Oidium neolycopersici conidia. Conidia of eight- to nine-day-old colonies were dusted on water agar surface in Petri dishes and exposed to UV treatments (without lid). Immediately after UV treatments, Petri dishes were sealed and incubated in darkness or differing optical environments generated using seven different radiation sources (range 290nm to 780nm). Twenty-four hours after UV treatment, fifty conidia from each sample were assessed for germination. Compared to non-UV controls, <10% of the conidia germinated after 30s of exposure to 254nm or 283nm UV and subsequent dark incubation. Conidia germination was almost negligible if the exposure duration increased to 4min. Germination was about 60% with broad spectrum UV after 1min of exposure, and about 35% after 2 to 4min of exposure. There was no reduction of conidia germination with the exposure of ≤4min with 310nm. With the tested wavelength and dose ranges, germination recovery was effective in the 350nm to 500nm range. Germination efficiency of conidia treated with effective UV was significantly higher (>73%) if incubated subsequently in the 350nm to 500nm range (germination recovery). Furthermore, germination recovery depends on the characteristics of UV treatment (wavelength, and duration of exposure) and the lapse time between UV treatment and subsequent exposure to optical radiation in the recovery range. The findings of this study provide key criteria for wavelength selection, combination and application time in the optical radiation range, enabling improved design of optical based management strategies against powdery mildews. Copyright © 2017 Elsevier B.V. All rights reserved.

Mixed-Methods Research Methodologies

ERIC Educational Resources Information Center

Terrell, Steven R.

2012-01-01

Mixed-Method studies have emerged from the paradigm wars between qualitative and quantitative research approaches to become a widely used mode of inquiry. Depending on choices made across four dimensions, mixed-methods can provide an investigator with many design choices which involve a range of sequential and concurrent strategies. Defining…

Alcohol and drug misuse, abuse, and dependence in women veterans.

PubMed

Hoggatt, Katherine J; Jamison, Andrea L; Lehavot, Keren; Cucciare, Michael A; Timko, Christine; Simpson, Tracy L

2015-01-01

We conducted a systematic literature review on substance misuse, abuse, and dependence in women veterans, including National Guard/reserve members. We identified 837 articles published between 1980 and 2013. Of 56 included studies, 32 reported rates of alcohol misuse, binge drinking, or other unhealthy alcohol use not meeting diagnostic criteria for abuse or dependence, and 33 reported rates of drug misuse or diagnosed alcohol or drug use disorders. Rates ranged from 4% to 37% for alcohol misuse and from 7% to 25% for binge drinking; among Veterans Health Administration (VA) health-care system outpatients, rates ranged from 3% to 16% for substance use disorder. Studies comparing women veterans and civilians reported no clear differences in binge or heavy drinking. Substance misuse rates were generally lower among women veterans than men veterans. Substance misuse was associated with higher rates of trauma, psychiatric and medical conditions, and increased mortality and suicide rates. Most studies included only VA patients, and many used only VA medical record data; therefore, the reported substance misuse rates likely do not reflect true prevalence. Rates also varied by assessment method, source of data, and the subgroups studied. Further efforts to develop epidemiologically valid prevalence estimates are needed to capture the true health burden of substance misuse in women veterans, particularly those not using VA care. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Electronic band structure effects in the stopping of protons in copper [Electronic band structure non-linear effects in the stopping of protons in copper

DOE PAGES

Quashie, Edwin E.; Saha, Bidhan C.; Correa, Alfredo A.

2016-10-05

Here, we present an ab initio study of the electronic stopping power of protons in copper over a wide range of proton velocities v = 0.02–10a.u. where we take into account nonlinear effects. Time-dependent density functional theory coupled with molecular dynamics is used to study electronic excitations produced by energetic protons. A plane-wave pseudopotential scheme is employed to solve the time-dependent Kohn-Sham equations for a moving ion in a periodic crystal. The electronic excitations and the band structure determine the stopping power of the material and alter the interatomic forces for both channeling and off-channeling trajectories. Our off-channeling results aremore » in quantitative agreement with experiments, and at low velocity they unveil a crossover region of superlinear velocity dependence (with a power of ~1.5) in the velocity range v = 0.07–0.3a.u., which we associate to the copper crystalline electronic band structure. The results are rationalized by simple band models connecting two separate regimes. We find that the limit of electronic stopping v → 0 is not as simple as phenomenological models suggest and it is plagued by band-structure effects.« less

Thickness-dependent change in the valence band offset of the SiO{sub 2}/Si interface studied using synchrotron-radiation photoemission spectroscopy

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

Toyoda, S., E-mail: toyoda.satoshi.4w@kyoto-u.ac.jp; Oshima, M.

2016-08-28

We have studied the thickness-dependent change in the valence band offset (VBO) of the SiO{sub 2}/Si(001) interface using synchrotron-radiation photoemission spectroscopy with soft and hard X-rays. The SiO{sub 2}-film thickness (T{sub ox}) and X-ray irradiation time (t{sub irrad}) were systematically parameterized to distinguish between the “intrinsic” T{sub ox} effects in the VBOs and the “extrinsic” differential charging phenomena in SiO{sub 2} films on Si substrates. The results revealed that at a spontaneous time (t{sub irrad} ≈ 5 s) that suppresses the differential charging phenomena as much as possible, the experimental VBO abruptly increases as a function of T{sub ox} and graduallymore » saturates to the traditional VBO value range determined by the internal photoemission and photoconduction measurements. This effect is not attributed to the differential charging phenomena, but rather it is attributed to the “intrinsic” T{sub ox}-dependent change in the VBO. The two possible physical behaviors include electronic polarization and image charge. We have derived the electronic polarization contribution from experimental data by carefully describing the effects of the long-range image charges based on the classical dielectric-screening model.« less

Temperature and molecular-weight dependences of acoustic behaviors of polystyrene studied using Brillouin spectroscopy

NASA Astrophysics Data System (ADS)

Oh, Soo Han; Lee, Byoung Wan; Ko, Jae-Hyeon; Lee, Hyeonju; Park, Jaehoon; Ko, Young Ho; Kim, Kwang Joo

2017-04-01

The acoustic properties of three polystyrene polymers with different molecular weights were investigated as a function of temperature by using Brillouin light scattering. The longitudinal sound velocity showed a change in the slope, which depended on the molecular weight, at the glass transition temperature. The absorption coefficient exhibited a maximum above the glass transition temperature, and the maximum temperature became higher as the molecular weight was increased. Comparison with previous acoustic studies on polystyrene indicate that a substantial frequency dispersion caused by strong coupling between the longitudinal acoustic waves and the segmental motions exists in the high-temperature range.

Elastic Scattering of 65 MeV Protons from Several Nuclei between 16O and 209Bi

NASA Astrophysics Data System (ADS)

Ahmed, Syed; Akther, Parvin; Ferdous, Nasima; Begum, Amena; Gupta, Hiranmay

1997-10-01

Elastic scattering of 65 MeV polarized protons from twenty five nuclei ranging from 16O to 209Bi have been analysed within the framework of the nine parameter optical model. A set of optical model parameters has been obtained which shows the systematic behaviour of the target mass dependence of the real potential, volume integral and the r.m.s. radius. The isotopic spin dependence of the real potential has also been studied. Parameters obtained by fitting the elastic scattering data have been able to reproduce the pickup and stripping reaction cross sections as studied in a few cases.

Concentration dependence of sodium alloys based on tin surface tension

NASA Astrophysics Data System (ADS)

Alchagirov, B. B.; Kyasova, O. Kh; Uzdenova, A. N.; Khibiev, A. Kh

2018-04-01

The concentration dependence of the surface tension (ST) for alloys of the Sn-Na system in the range of compositions with a content of 0.06 to 5.00 at.% Na is studied by the large droplet method using high-purity components and a corresponding ST isotherm for T = 573 K is constructed. It has been established that small additions of sodium to tin significantly reduce ST of the studied melts. Calculations of sodium adsorption in alloys have shown that there is a maximum on the adsorption curve corresponding to alloys with a content of about 1.5 at.% Na in tin.

Surface Plasmon Polariton Resonance of Gold, Silver, and Copper Studied in the Kretschmann Geometry: Dependence on Wavelength, Angle of Incidence, and Film Thickness

NASA Astrophysics Data System (ADS)

Takagi, Kentaro; Nair, Selvakumar V.; Watanabe, Ryosuke; Seto, Keisuke; Kobayashi, Takayoshi; Tokunaga, Eiji

2017-12-01

Surface plasmon polariton (SPP) resonance spectra for noble metals (Au, Ag, and Cu) were comprehensively studied in the Kretschmann attenuated total reflection (ATR) geometry, in the wavelength (λ) range from 300 to 1000 nm with the angle of incidence (θ) ranging from 45 to 60° and the film thickness (d) ranging from 41 to 76 nm. The experimental plasmon resonance spectra were reproduced by a calculation that included the broadening effects as follows: (1) the imaginary part of the bulk dielectric constant, (2) the thickness-dependent radiative coupling of the SPP at the metal-air interface to the prism, (3) the lack of conservation of the wavevector parallel to the interface kx(k||) caused by the surface roughness, (4) scanning λ at a fixed θ (changing both energy and kx at the same time) over the SPP dispersion relation. For Au and Ag, the experimental results were in good agreement with the calculated results using the bulk dielectric constants, showing no film thickness dependence of the plasmon resonance energy. A method to extract the true width of the plasmon resonance from raw ATR spectra is proposed and the results are rigorously compared with those expected from the bulk dielectric function given in the literature. For Au and Ag, the width increases with energy, in agreement with that expected from the relaxation of bulk free electrons including the electron-electron interaction, but there is clear evidence of extra broadening, which is more significant for thinner films, possibly due to relaxation pathways intrinsic to plasmons near the interface. For Cu, the visibility of the plasmon resonance critically depends on the evaporation conditions, and low pressures and fast deposition rates are required. Otherwise, scattering from the surface roughness causes considerable broadening of the plasmon resonance, resulting in an apparently fixed resonance energy without clear incident angle dependence. For Cu, the observed plasmon dispersion agrees well with that expected from the bulk dielectric function even with nominal oxidation of the surface, but the widths at long wavelengths are much larger than those theoretically expected.

Psychometric Validation of the Leeds Dependence Questionnaire (LDQ) in a Young Adult Clinical Sample

PubMed Central

Kelly, John F.; Magill, Molly; Slaymaker, Valerie; Kahler, Christopher

2013-01-01

Objective Measures of substance dependence severity that are both clinically efficient and sensitive to change can facilitate assessment of clinical innovation necessary for improving current evidence-based practices. The Leeds Dependence Questionnaire (LDQ) is a 10-item, continuous, self-report measure of dependence that is not specific to any particular substance and has shown promise in preliminary psychometric research. The present study investigates its psychometric properties in a large clinical sample of young adults. Method Emerging adults (N = 300) were enrolled in a naturalistic treatment process and outcome study of residential substance dependence treatment (mean age 20.4 [1.6], range 18–25; 27% female; 95% White). Dependence severity by demographic and diagnostic groupings, factor structure and internal consistency, and criterion- and construct-related validity were examined. Results Dependence severity in this cohort of youth overall was high (M = 18.65 [8.65]). LDQ scores were highest among opiate and stimulant users, and there was a trend for higher scores among women compared to men (t = 1.869, p = .063). Factor analysis using a robust alpha factoring extraction revealed a single factor accounting for 63% of the variance in reported dependence severity. The internal consistency was also very high (alpha = .93). Concurrent and convergent validity with dependence criteria, substance use frequency, and general symptom severity, respectively, were also acceptable. Conclusions The LDQ shows considerable promise as a brief, psychometrically sound, measure of substance dependence useful across a variety of substances, that has clinical and research utility. This study supports its use among emerging adults. PMID:20004062

Non-Maximal Tripartite Entanglement Degradation of Dirac and Scalar Fields in Non-Inertial Frames

NASA Astrophysics Data System (ADS)

Salman, Khan; Niaz, Ali Khan; M. K., Khan

2014-03-01

The π-tangle is used to study the behavior of entanglement of a nonmaximal tripartite state of both Dirac and scalar fields in accelerated frame. For Dirac fields, the degree of degradation with acceleration of both one-tangle of accelerated observer and π-tangle, for the same initial entanglement, is different by just interchanging the values of probability amplitudes. A fraction of both one-tangles and the π-tangle always survives for any choice of acceleration and the degree of initial entanglement. For scalar field, the one-tangle of accelerated observer depends on the choice of values of probability amplitudes and it vanishes in the range of infinite acceleration, whereas for π-tangle this is not always true. The dependence of π-tangle on probability amplitudes varies with acceleration. In the lower range of acceleration, its behavior changes by switching between the values of probability amplitudes and for larger values of acceleration this dependence on probability amplitudes vanishes. Interestingly, unlike bipartite entanglement, the degradation of π-tangle against acceleration in the case of scalar fields is slower than for Dirac fields.

Frequency-selective fading statistics of shallow-water acoustic communication channel with a few multipaths

NASA Astrophysics Data System (ADS)

Bae, Minja; Park, Jihyun; Kim, Jongju; Xue, Dandan; Park, Kyu-Chil; Yoon, Jong Rak

2016-07-01

The bit error rate of an underwater acoustic communication system is related to multipath fading statistics, which determine the signal-to-noise ratio. The amplitude and delay of each path depend on sea surface roughness, propagation medium properties, and source-to-receiver range as a function of frequency. Therefore, received signals will show frequency-dependent fading. A shallow-water acoustic communication channel generally shows a few strong multipaths that interfere with each other and the resulting interference affects the fading statistics model. In this study, frequency-selective fading statistics are modeled on the basis of the phasor representation of the complex path amplitude. The fading statistics distribution is parameterized by the frequency-dependent constructive or destructive interference of multipaths. At a 16 m depth with a muddy bottom, a wave height of 0.2 m, and source-to-receiver ranges of 100 and 400 m, fading statistics tend to show a Rayleigh distribution at a destructive interference frequency, but a Rice distribution at a constructive interference frequency. The theoretical fading statistics well matched the experimental ones.

Acute ethanol ingestion produces dose-dependent effects on motor behavior in the honey bee (Apis mellifera).

PubMed

Maze, Ian S; Wright, Geraldine A; Mustard, Julie A

2006-01-01

Ethanol consumption produces characteristic behavioral states in animals that include sedation, disorientation, and disruption of motor function. Using individual honey bees, we assessed the effects of ethanol ingestion on motor function via continuous observations of their behavior. Consumption of 1 M sucrose solutions containing a range of ethanol doses led to hemolymph ethanol levels of approximately 40-100 mM. Using ethanol doses in this range, we observed time and dose-dependent effects of ethanol on the percent of time our subjects spent walking, stopped, or upside down, and on the duration and frequency of bouts of behavior. The effects on grooming and flying behavior were more complex. Behavioral recovery from ethanol treatment was both time and ethanol dose dependent, occurring between 12 and 24 h post-ingestion for low doses and at 24-48 h for higher doses. Furthermore, the amount of ethanol measured in honey bee hemolymph appeared to correlate with recovery. We predict that the honey bee will prove to be an excellent model system for studying the influence of ethanol on the neural mechanisms underlying behavior.

Temperature-Dependent Dielectric Properties of Al/Epoxy Nanocomposites

NASA Astrophysics Data System (ADS)

Wang, Zijun; Zhou, Wenying; Sui, Xuezhen; Dong, Lina; Cai, Huiwu; Zuo, Jing; Chen, Qingguo

2016-06-01

Broadband dielectric spectroscopy was carried out to study the transition in electrical properties of Al/epoxy nanocomposites over the frequency range of 1-107 Hz and the temperature range of -20°C to 200°C. The dielectric permittivity, dissipation factor, and electrical conductivity of the nanocomposites increased with temperature and showed an abrupt increase around the glass transition temperature ( T g). The results clearly reveal an interesting transition of the electrical properties with increasing temperature: insulator below 70°C, conductor at about 70°C. The behavior of the transition in electrical properties of the nanocomposites was explored at different temperatures. The presence of relaxation peaks in the loss tangent and electric modulus spectra of the nanocomposites confirms that the chain segmental dynamics of the polymer is accompanied by the absorption of energy given to the system. It is suggested that the temperature-dependent transition of the electric properties in the nanocomposite is closely associated with the α-relaxation. The large increase in the dissipation factor and electric conductivity depends on the direct current conduction of thermally activated charge carriers resulting from the epoxy matrix above T g.

Neutron-proton effective mass splitting in terms of symmetry energy and its density slope

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

Chakraborty, S.; Sahoo, B.; Sahoo, S., E-mail: sukadevsahoo@yahoo.com

2015-01-15

Using a simple density-dependent finite-range effective interaction having Yukawa form, the density dependence of isoscalar and isovector effective masses is studied. The isovector effective mass is found to be different for different pairs of like and unlike nucleons. Using HVH theorem, the neutron-proton effective mass splitting is represented in terms of symmetry energy and its density slope. It is again observed that the neutron-proton effective mass splitting has got a positive value when isoscalar effective mass is greater than the isovector effective mass and has a negative value for the opposite case. Furthermore, the neutron-proton effective mass splitting is foundmore » to have a linear dependence on asymmetry β. The second-order symmetry potential has a vital role in the determination of density slope of symmetry energy but it does not have any contribution on neutron-proton effective mass splitting. The finite-range effective interaction is compared with the SLy2, SKM, f{sub −}, f{sub 0}, and f{sub +} forms of interactions.« less

Effect of strain wave shape on low-cycle fatigue crack propagation of SUS 304 stainless steel at elevated temperatures

NASA Astrophysics Data System (ADS)

Okazaki, Masakazu; Hattori, Ichiro; Shiraiwa, Fujio; Koizumi, Takashi

1983-08-01

Effect of strain wave shape on strain-controlled low-cycle fatigue crack propagation of SUS 304 stainless steel was investigated at 600 and 700 °C. It was found that the rate of crack propagation in a cycle-dependent region was successfully correlated with the range of cyclic J-integral, Δ Jf, regardless of the strain wave shape, frequency, and test temperature. It was also shown that the rate of crack propagation gradually increased from cycle-dependent curve to time-dependent one with decreasing frequency and slow-fast strain wave shape, and that one of the factors governing the rate of crack propagation in such a region was the ratio of the range of creep J-integral to that of total J-integral, Δ J c/Δ JT. Based on the results thus obtained, an interaction damage rule proposed semi-empirically was interpreted, with regard to crack propagation. Furthermore, fatigue crack initiation mechanism in slow-fast strain wave shape was studied, and it was shown that grain boundary sliding took an important role in it.

Wavelength dependence of Verdet constant of Tb{sup 3+}:Y{sub 2}O{sub 3} ceramics

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

Snetkov, I. L., E-mail: snetkov@appl.sci-nnov.ru; Palashov, O. V.; Permin, D. A.

2016-04-18

Samples of the magneto-active material—Tb{sup 3+}:Y{sub 2}O{sub 3} ceramics with Tb{sup 3+} ion concentrations of 10%, 20%, 30%, and 100% (Tb{sub 2}O{sub 3})—were prepared and studied. The wavelength dependence of Verdet constant in the 380 nm–1750 nm range was approximated for all investigated ceramic samples and was predicted for a pure Tb{sub 2}O{sub 3} material. Tb{sub 2}O{sub 3} ceramics demonstrates a more than three times higher Verdet constant in comparison with terbium gallium garnet crystal or ceramics. The linear dependence of the Verdet constant on Tb{sup 3+} ion concentration in the Tb{sup 3+}:Y{sub 2}O{sub 3} ceramics was demonstrated. The obtained data willmore » be useful for fabricating magneto-optical elements of Faraday devices based on Tb{sup 3+}:Y{sub 2}O{sub 3} with arbitrary Tb{sup 3+} ion concentration operating at room temperature in the wavelength range of 380 nm–1750 nm.« less

Long-time predictability in disordered spin systems following a deep quench

NASA Astrophysics Data System (ADS)

Ye, J.; Gheissari, R.; Machta, J.; Newman, C. M.; Stein, D. L.

2017-04-01

We study the problem of predictability, or "nature vs nurture," in several disordered Ising spin systems evolving at zero temperature from a random initial state: How much does the final state depend on the information contained in the initial state, and how much depends on the detailed history of the system? Our numerical studies of the "dynamical order parameter" in Edwards-Anderson Ising spin glasses and random ferromagnets indicate that the influence of the initial state decays as dimension increases. Similarly, this same order parameter for the Sherrington-Kirkpatrick infinite-range spin glass indicates that this information decays as the number of spins increases. Based on these results, we conjecture that the influence of the initial state on the final state decays to zero in finite-dimensional random-bond spin systems as dimension goes to infinity, regardless of the presence of frustration. We also study the rate at which spins "freeze out" to a final state as a function of dimensionality and number of spins; here the results indicate that the number of "active" spins at long times increases with dimension (for short-range systems) or number of spins (for infinite-range systems). We provide theoretical arguments to support these conjectures, and also study analytically several mean-field models: the random energy model, the uniform Curie-Weiss ferromagnet, and the disordered Curie-Weiss ferromagnet. We find that for these models, the information contained in the initial state does not decay in the thermodynamic limit—in fact, it fully determines the final state. Unlike in short-range models, the presence of frustration in mean-field models dramatically alters the dynamical behavior with respect to the issue of predictability.

Long-time predictability in disordered spin systems following a deep quench.

PubMed

Ye, J; Gheissari, R; Machta, J; Newman, C M; Stein, D L

2017-04-01

We study the problem of predictability, or "nature vs nurture," in several disordered Ising spin systems evolving at zero temperature from a random initial state: How much does the final state depend on the information contained in the initial state, and how much depends on the detailed history of the system? Our numerical studies of the "dynamical order parameter" in Edwards-Anderson Ising spin glasses and random ferromagnets indicate that the influence of the initial state decays as dimension increases. Similarly, this same order parameter for the Sherrington-Kirkpatrick infinite-range spin glass indicates that this information decays as the number of spins increases. Based on these results, we conjecture that the influence of the initial state on the final state decays to zero in finite-dimensional random-bond spin systems as dimension goes to infinity, regardless of the presence of frustration. We also study the rate at which spins "freeze out" to a final state as a function of dimensionality and number of spins; here the results indicate that the number of "active" spins at long times increases with dimension (for short-range systems) or number of spins (for infinite-range systems). We provide theoretical arguments to support these conjectures, and also study analytically several mean-field models: the random energy model, the uniform Curie-Weiss ferromagnet, and the disordered Curie-Weiss ferromagnet. We find that for these models, the information contained in the initial state does not decay in the thermodynamic limit-in fact, it fully determines the final state. Unlike in short-range models, the presence of frustration in mean-field models dramatically alters the dynamical behavior with respect to the issue of predictability.

A study of the effects of strong magnetic fields on the image resolution of PET scanners

NASA Astrophysics Data System (ADS)

Burdette, Don J.

Very high resolution images can be achieved in small animal PET systems utilizing solid state silicon pad detectors. In such systems using detectors with sub-millimeter intrinsic resolutions, the range of the positron is the largest contribution to the image blur. The size of the positron range effect depends on the initial positron energy and hence the radioactive tracer used. For higher energy positron emitters, such as 68Ga and 94mTc, the variation of the annihilation point dominates the spatial resolution. In this study two techniques are investigated to improve the image resolution of PET scanners limited by the range of the positron. One, the positron range can be reduced by embedding the PET field of view in a strong magnetic field. We have developed a silicon pad detector based PET instrument that can operate in strong magnetic fields with an image resolution of 0.7 mm FWHM to study this effect. Two, iterative reconstruction methods can be used to statistically correct for the range of the positron. Both strong magnetic fields and iterative reconstruction algorithms that statistically account for the positron range distribution are investigated in this work.

Dynamic Simulation of Random Packing of Polydispersive Fine Particles

NASA Astrophysics Data System (ADS)

Ferraz, Carlos Handrey Araujo; Marques, Samuel Apolinário

2018-02-01

In this paper, we perform molecular dynamic (MD) simulations to study the two-dimensional packing process of both monosized and random size particles with radii ranging from 1.0 to 7.0 μm. The initial positions as well as the radii of five thousand fine particles were defined inside a rectangular box by using a random number generator. Both the translational and rotational movements of each particle were considered in the simulations. In order to deal with interacting fine particles, we take into account both the contact forces and the long-range dispersive forces. We account for normal and static/sliding tangential friction forces between particles and between particle and wall by means of a linear model approach, while the long-range dispersive forces are computed by using a Lennard-Jones-like potential. The packing processes were studied assuming different long-range interaction strengths. We carry out statistical calculations of the different quantities studied such as packing density, mean coordination number, kinetic energy, and radial distribution function as the system evolves over time. We find that the long-range dispersive forces can strongly influence the packing process dynamics as they might form large particle clusters, depending on the intensity of the long-range interaction strength.

Sensing small neurotransmitter-enzyme interaction with nanoporous gated ion-sensitive field effect transistors.

PubMed

Kisner, Alexandre; Stockmann, Regina; Jansen, Michael; Yegin, Ugur; Offenhäusser, Andreas; Kubota, Lauro Tatsuo; Mourzina, Yulia

2012-01-15

Ion-sensitive field effect transistors with gates having a high density of nanopores were fabricated and employed to sense the neurotransmitter dopamine with high selectivity and detectability at micromolar range. The nanoporous structure of the gates was produced by applying a relatively simple anodizing process, which yielded a porous alumina layer with pores exhibiting a mean diameter ranging from 20 to 35 nm. Gate-source voltages of the transistors demonstrated a pH-dependence that was linear over a wide range and could be understood as changes in surface charges during protonation and deprotonation. The large surface area provided by the pores allowed the physical immobilization of tyrosinase, which is an enzyme that oxidizes dopamine, on the gates of the transistors, and thus, changes the acid-base behavior on their surfaces. Concentration-dependent dopamine interacting with immobilized tyrosinase showed a linear dependence into a physiological range of interest for dopamine concentration in the changes of gate-source voltages. In comparison with previous approaches, a response time relatively fast for detecting dopamine was obtained. Additionally, selectivity assays for other neurotransmitters that are abundantly found in the brain were examined. These results demonstrate that the nanoporous structure of ion-sensitive field effect transistors can easily be used to immobilize specific enzyme that can readily and selectively detect small neurotransmitter molecule based on its acid-base interaction with the receptor. Therefore, it could serve as a technology platform for molecular studies of neurotransmitter-enzyme binding and drugs screening. Copyright © 2011 Elsevier B.V. All rights reserved.

A path-dependent fatigue crack propagation model under non-proportional modes I and III loading conditions

DOE PAGES

Mei, J.; Dong, P.; Kalnaus, S.; ...

2017-07-21

It has been well established that fatigue damage process is load-path dependent under non-proportional multi-axial loading conditions. Most of studies to date have been focusing on interpretation of S-N based test data by constructing a path-dependent fatigue damage model. Our paper presents a two-parameter mixed-mode fatigue crack growth model which takes into account of crack growth dependency on both load path traversed and a maximum effective stress intensity attained in a stress intensity factor plane (e.g.,KI-KIII plane). Furthermore, by taking advantage of a path-dependent maximum range (PDMR) cycle definition (Dong et al., 2010; Wei and Dong, 2010), the two parametersmore » are formulated by introducing a moment of load path (MLP) based equivalent stress intensity factor range (ΔKNP) and a maximum effective stress intensity parameter KMax incorporating an interaction term KI·KIII. To examine the effectiveness of the proposed model, two sets of crack growth rate test data are considered. The first set is obtained as a part of this study using 304 stainless steel disk specimens subjected to three combined non-proportional modes I and III loading conditions (i.e., with a phase angle of 0°, 90°, and 180°). The second set was obtained by Feng et al. (2007) using 1070 steel disk specimens subjected to similar types of non-proportional mixed-mode conditions. Once the proposed two-parameter non-proportional mixed-mode crack growth model is used, it is shown that a good correlation can be achieved for both sets of the crack growth rate test data.« less

A path-dependent fatigue crack propagation model under non-proportional modes I and III loading conditions

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

Mei, J.; Dong, P.; Kalnaus, S.

It has been well established that fatigue damage process is load-path dependent under non-proportional multi-axial loading conditions. Most of studies to date have been focusing on interpretation of S-N based test data by constructing a path-dependent fatigue damage model. Our paper presents a two-parameter mixed-mode fatigue crack growth model which takes into account of crack growth dependency on both load path traversed and a maximum effective stress intensity attained in a stress intensity factor plane (e.g.,KI-KIII plane). Furthermore, by taking advantage of a path-dependent maximum range (PDMR) cycle definition (Dong et al., 2010; Wei and Dong, 2010), the two parametersmore » are formulated by introducing a moment of load path (MLP) based equivalent stress intensity factor range (ΔKNP) and a maximum effective stress intensity parameter KMax incorporating an interaction term KI·KIII. To examine the effectiveness of the proposed model, two sets of crack growth rate test data are considered. The first set is obtained as a part of this study using 304 stainless steel disk specimens subjected to three combined non-proportional modes I and III loading conditions (i.e., with a phase angle of 0°, 90°, and 180°). The second set was obtained by Feng et al. (2007) using 1070 steel disk specimens subjected to similar types of non-proportional mixed-mode conditions. Once the proposed two-parameter non-proportional mixed-mode crack growth model is used, it is shown that a good correlation can be achieved for both sets of the crack growth rate test data.« less

Photo-Hall-effect study of excitation and recombination in Fe-doped GaN

NASA Astrophysics Data System (ADS)

Look, David C.; Leach, Jacob H.; Metzger, Robert

2017-02-01

The photo-Hall-effect was applied to the study of electron dynamics in semi-insulating Fe-doped GaN. High-powered light-emitting diodes of wavelengths λ = 940, 536, 449, 402, and 365 nm were used to excite steady-state free-electron volume concentrations Δn = 105-108 cm-3, depending on λ and intensity I0. Electron lifetime τ was determined from the energy E dependence of the excited sheet electron concentration Δns through the relationship Δns = I0τA(E), where the absorbance A(E) is a known function of sample thickness d and absorption coefficient α, and the energy dependence of α is taken from a theory of deep-center photoionization. The major sample impurities were Fe, Si, and C, with [Fe] ≫ [Si] and [C]. Fitted lifetimes τ ranged from 15 to 170 ps, depending on [Fe]. It was found that Δns ∝ I0 for [Si] > [C] and ∝ I01/2 for [Si] < [C]; the latter dependence arises possibly from self-compensation of neutral C impurities by N-vacancy donors. For [Si] > [C], some of the neutral Fe3+ is converted to Fe2+ with ground state Fe2+(5E) and excited state Fe2+(5T2); a fit of n vs. temperature T over the range of 290-325 K in the dark establishes E5E with respect to the conduction band: ECB - E5E = 0.564 eV - β5ET, where β5E = 3.6 × 10-4 eV/K. At room temperature, 294 K, ECB - E5E = 0.46 eV and ECB - E5T2 = 0.07 eV.

Impact of the Nationwide Intravenous Selenium Product Shortage on the Development of Selenium Deficiency in Infants Dependent on Long-Term Parenteral Nutrition.

PubMed

Chen, Connie H; Harris, Mary Beth; Partipilo, M Luisa; Welch, Kathleen B; Teitelbaum, Daniel H; Blackmer, Allison B

2016-08-01

For patients dependent on parenteral nutrition (PN), selenium must be supplemented intravenously. A nationwide intravenous selenium shortage began in April 2011. The impact of this shortage on PN-dependent infants was evaluated by examining the provision of selenium, development of biochemical deficiency, and costs associated with the shortage. This single-center, retrospective study included PN-dependent infants aged ≤1 year who weighed ≤30 kg, received PN for ≥1 month, and had ≥1 serum selenium measurement. The primary outcome was the incidence of biochemical selenium deficiency. Secondary outcomes included severity of biochemical deficiency, clinical manifestations, costs, and relationship between serum selenium levels and selenium dose. The average selenium dose decreased 2-fold during the shortage (2.1 ± 1.2 µg/kg/d; range, 0.2-4.6 µg/kg/d) versus the nonshortage period (3.8 ± 1 µg/kg/d; range, 2.4-6 µg/kg/d; P < .001). A linear relationship between serum selenium concentration and selenium dose was observed (r(2) = 0.42), with a dose of 6 µg/kg/d expected to result in normal serum levels in most cases. Similar proportions of patients developed biochemical deficiency in both groups: shortage period, 59.1%; nonshortage, 66.7%; P = .13. The severity of biochemical deficiency was similar between groups. A significant increase in incremental cost during the shortage was observed. This is the first study examining the impact of the intravenous selenium shortage on PN-dependent infants. Both groups exhibited similarly high incidences of biochemical selenium deficiency, suggesting higher empiric doses may benefit this population. However, ongoing shortages limit the ability to provide supplementation. © 2015 American Society for Parenteral and Enteral Nutrition.

Foliar damage beyond species distributions is partly explained by distance dependent interactions with natural enemies.

PubMed

Katz, Daniel S W; Ibáñez, Inés

2016-09-01

Plant distributions are expected to shift in response to climate change, and range expansion dynamics will be shaped by the performance of individuals at the colonizing front. These plants will encounter new biotic communities beyond their range edges, and the net outcome of these encounters could profoundly affect colonization success. However, little is known about how biotic interactions vary across range edges and this has hindered efforts to predict changes in species distributions in response to climate change. In contrast, a rich literature documents how biotic interactions within species ranges vary according to distance to and density of conspecific individuals. Here, we test whether this framework can be extended to explain how biotic interactions differ beyond range edges, where conspecific adults are basically absent. To do so, we planted seven species of trees along a 450-km latitudinal gradient that crossed the current distributional range of five of these species and monitored foliar disease and invertebrate herbivory over 5 yr. Foliar disease and herbivory were analyzed as a function of distance to and density of conspecific and congeneric trees at several spatial scales. We found that within species ranges foliar disease was lower for seedlings that were farther from conspecific adults for Acer rubrum, Carya glabra, Quercus alba, and Robinia pseudoacacia. Beyond range edges, there was even less foliar disease for C. glabra, Q. alba, and R. pseudoacacia (A. rubrum was not planted outside its range). Liriodendron tulipifera did not experience reduced disease within or beyond its range. In contrast, Quercus velutina displayed significant but idiosyncratic patterns in disease at varying distances from conspecifics. Patterns of distance dependent herbivory across spatial scales was generally weak and in some cases negative (i.e., seedlings farther from conspecific adults had more herbivory). Overall, we conclude that differences in biotic interactions across range edges can be thought of as a spatial extension to the concept of distance dependent biotic interactions. This framework also provides the basis for general predictions of how distance dependent biotic interactions will change across range edges in other systems. © 2016 by the Ecological Society of America.

Fine-scale genetic structure arises during range expansion of an invasive gecko.

PubMed

Short, Kristen Harfmann; Petren, Kenneth

2011-01-01

Processes of range expansion are increasingly important in light of current concerns about invasive species and range shifts due to climate change. Theoretical studies suggest that genetic structuring may occur during range expansion. Ephemeral genetic structure can have important evolutionary implications, such as propagating genetic changes along the wave front of expansion, yet few studies have shown evidence of such structure. We tested the hypothesis that genetic structure arises during range expansion in Hemidactylus mabouia, a nocturnal African gecko recently introduced to Florida, USA. Twelve highly variable microsatellite loci were used to screen 418 individuals collected from 43 locations from four sampling sites across Florida, representing a gradient from earlier (∼1990s) to very recent colonization. We found earlier colonized locations had little detectable genetic structure and higher allelic richness than more recently colonized locations. Genetic structuring was pronounced among locations at spatial scales of tens to hundreds of meters near the leading edge of range expansion. Despite the rapid pace of range expansion in this introduced gecko, dispersal is limited among many suitable habitat patches. Fine-scale genetic structure is likely the result of founder effects during colonization of suitable habitat patches. It may be obscured over time and by scale-dependent modes of dispersal. Further studies are needed to determine if such genetic structure affects adaptation and trait evolution in range expansions and range shifts.

Shear stress induced stimulation of mammalian cell metabolism

NASA Technical Reports Server (NTRS)

Mcintire, L. V.; Frangos, J. A.; Eskin, S. G.

1988-01-01

A flow apparatus was developed for the study of the metabolic response of anchorage dependent cells to a wide range of steady and pulsatile shear stresses under well controlled conditions. Human umbilical vein endothelial cell monolayers were subjected to steady shear stresses of up to 24 dynes/sq cm, and the production of prostacyclin was determined. The onset of flow led to a burst in prostacyclin production which decayed to a long term steady state rate (SSR). The SSR of cells exposed to flow was greater than the basal release level, and increased linearly with increasing shear stress. It is demonstrated that shear stresses in certain ranges may not be detrimental to mammalian cell metabolism. In fact, throughout the range of shear stresses studied, metabolite production is maximized by maximizing shear stress.

Dependence of magnetic anisotropy on MgO sputtering pressure in Co20Fe60B20/MgO stacks

NASA Astrophysics Data System (ADS)

Kaidatzis, A.; Serletis, C.; Niarchos, D.

2017-10-01

We investigated the dependence of magnetic anisotropy of Ta/Co20Fe60B20/MgO stacks on the Ar partial pressure during MgO deposition, in the range between 0.5 and 15 mTorr. The stacks are studied before and after annealing at 300°C and it is shown that magnetic anisotropy significantly depends on Ar partial pressure. High pressure results in stacks with very low perpendicular magnetic anisotropy even after annealing, while low pressure results in stacks with perpendicular anisotropy even at the as-deposited state. A monotonic increase of magnetic anisotropy energy is observed as Ar partial pressure is decreased.

Some Correlates of Risky Sexual Behavior among Secondary School Adolescents in Ogun State, Nigeria

ERIC Educational Resources Information Center

Adeyemo, D. A.; Williams, T. M.

2009-01-01

The purpose of the study is to examine factors associated with risky sexual behaviors among secondary school adolescents in Ogun State, Nigeria. Two hundred and fifty adolescents randomly selected from three schools participated in the study. The ages of the participants ranged from 13 to 18 years. Both the independent and dependent variables were…

The exact solution of a four-body Coulomb problem

NASA Astrophysics Data System (ADS)

Ray, Hasi

2018-03-01

The elastic collision between two H-like atoms utilizing an ab initio static-exchange model (SEM) in the center of mass (CM) frame considering the system as a four-body Coulomb problem where all the Coulomb interaction terms in the direct and exchange channels are treated exactly, is studied thoroughly. A coupled-channel methodology in momentum space is used to solve Lippman-Schwinger equation following the integral approach. The new SEM code [Ray, Pramana 83, 907 (2014)] in which the Born-Oppenheimer (BO) scattering amplitude acts as input to derive the SEM amplitude using partial wave analysis, is utilized to study the s-, p-, d-wave elastic phase shifts and the corresponding partial cross sections. An augmented-Born approximation is used to include the contribution of higher partial waves more accurately to determine the total/integrated elastic cross sections. The effective range theory is used to determine the scattering lengths and effective ranges in the s-wave elastic scattering. The systems studied are Ps-Ps, Ps-Mu, Ps-H, Ps-D, Ps-T, Mu-Mu, Mu-H, Mu-D, Mu-T, H-H, H-D, H-T, D-D, D-T, T-T. The SEM includes the non-adiabatic short-range effects due to exchange. The MSEM code [Ray, Pramana 83, 907 (2014)] is used to study the effect of the long-range van der Waals interaction due to induced dipole polarizabilities of the atoms in H(1s)-H(1s) elastic collision. The dependence of scattering length on the reduced mass of the system and the dependence of scattering length on the strength of long-range van der Waals interaction that varies with the minimum interatomic distance are observed. Contribution to the Topical Issue "Low Energy Positron and Electron Interactions", edited by James Sullivan, Ron White, Michael Bromley, Ilya Fabrikant, and David Cassidy.

Host- and stage-dependent secretome of the arbuscular mycorrhizal fungus Rhizophagus irregularis.

PubMed

Zeng, Tian; Holmer, Rens; Hontelez, Jan; Te Lintel-Hekkert, Bas; Marufu, Lucky; de Zeeuw, Thijs; Wu, Fangyuan; Schijlen, Elio; Bisseling, Ton; Limpens, Erik

2018-05-01

Arbuscular mycorrhizal fungi form the most wide-spread endosymbiosis with plants. There is very little host specificity in this interaction, however host preferences as well as varying symbiotic efficiencies have been observed. We hypothesize that secreted proteins (SPs) may act as fungal effectors to control symbiotic efficiency in a host-dependent manner. Therefore, we studied whether arbuscular mycorrhizal (AM) fungi adjust their secretome in a host- and stage-dependent manner to contribute to their extremely wide host range. We investigated the expression of SP-encoding genes of Rhizophagus irregularis in three evolutionary distantly related plant species, Medicago truncatula, Nicotiana benthamiana and Allium schoenoprasum. In addition we used laser microdissection in combination with RNA-seq to study SP expression at different stages of the interaction in Medicago. Our data indicate that most expressed SPs show roughly equal expression levels in the interaction with all three host plants. In addition, a subset shows significant differential expression depending on the host plant. Furthermore, SP expression is controlled locally in the hyphal network in response to host-dependent cues. Overall, this study presents a comprehensive analysis of the R. irregularis secretome, which now offers a solid basis to direct functional studies on the role of fungal SPs in AM symbiosis. © 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Ltd.

Large-visual-angle microstructure inspired from quantitative design of Morpho butterflies' lamellae deviation using the FDTD/PSO method.

PubMed

Wang, Wanlin; Zhang, Wang; Chen, Weixin; Gu, Jiajun; Liu, Qinglei; Deng, Tao; Zhang, Di

2013-01-15

The wide angular range of the treelike structure in Morpho butterfly scales was investigated by finite-difference time-domain (FDTD)/particle-swarm-optimization (PSO) analysis. Using the FDTD method, different parameters in the Morpho butterflies' treelike structure were studied and their contributions to the angular dependence were analyzed. Then a wide angular range was realized by the PSO method from quantitatively designing the lamellae deviation (Δy), which was a crucial parameter with angular range. The field map of the wide-range reflection in a large area was given to confirm the wide angular range. The tristimulus values and corresponding color coordinates for various viewing directions were calculated to confirm the blue color in different observation angles. The wide angular range realized by the FDTD/PSO method will assist us in understanding the scientific principles involved and also in designing artificial optical materials.

Temperature Dependence of Inorganic Nitrogen Uptake: Reduced Affinity for Nitrate at Suboptimal Temperatures in Both Algae and Bacteria

PubMed Central

Reay, David S.; Nedwell, David B.; Priddle, Julian; Ellis-Evans, J. Cynan

1999-01-01

Nitrate utilization and ammonium utilization were studied by using three algal isolates, six bacterial isolates, and a range of temperatures in chemostat and batch cultures. We quantified affinities for both substrates by determining specific affinities (specific affinity = maximum growth rate/half-saturation constant) based on estimates of kinetic parameters obtained from chemostat experiments. At suboptimal temperatures, the residual concentrations of nitrate in batch cultures and the steady-state concentrations of nitrate in chemostat cultures both increased. The specific affinity for nitrate was strongly dependent on temperature (Q10 ≈ 3, where Q10 is the proportional change with a 10°C temperature increase) and consistently decreased at temperatures below the optimum temperature. In contrast, the steady-state concentrations of ammonium remained relatively constant over the same temperature range, and the specific affinity for ammonium exhibited no clear temperature dependence. This is the first time that a consistent effect of low temperature on affinity for nitrate has been identified for psychrophilic, mesophilic, and thermophilic bacteria and algae. The different responses of nitrate uptake and ammonium uptake to temperature imply that there is increasing dependence on ammonium as an inorganic nitrogen source at low temperatures. PMID:10347046

The Influence of Phonons and Phonon Decay on the Optical Properties of GaN

NASA Astrophysics Data System (ADS)

Song, D. Y.; Basavaraj, M.; Nikishin, S. A.; Holtz, M.; Soukhoveev, V.; Usikov, A.; Dmitriev, V.

2006-03-01

The temperature dependences of vibrational and optical properties of high-quality GaN are studied using Raman and photoluminescence (PL) spectroscopies in the range 20 to 325 K. The Raman-active A1(LO) phonon has temperature dependence described well by combined two- and three-phonon decay. The temperature dependences of E2^2 phonon are almost entirely dominated by the thermal expansion, and the contribution of three-phonon decay process is very small throughout interested temperature range. The shallow neutral donor-bound exciton (D^0,X) and two free excitons (XA and XB) are observed at low temperatrue PL spectra. Also seen are two A1(LO) phonon sidebands (PSBs), originating from the XB free exciton, with the characteristic asymmetry attributed to interactions between discrete and continuum states. Analysis of the band-edge excitons reveals that energy gap shrinkage and exciton linewidths are completely described based on electron-phonon interactions with phonon properties consistent with the Raman analysis. First and second PSBs have temperature dependence associated with the A1(LO) phonon. The shift, broadening, and asymmetry of the PSBs are explained by Segall-Mahan theory adding the decay mechanism of A1(LO) phonon and the exciton broadening from electron-phonon interactions. Work at Texas Tech University supported by National Science Foundation grant ECS-0323640.

Constraints on flavor-dependent long range forces from solar neutrinos and KamLAND

NASA Astrophysics Data System (ADS)

Bandyopadhyay, Abhijit; Dighe, Amol; Joshipura, Anjan S.

2007-05-01

Flavor-dependent long range (LR) leptonic forces, like those mediated by the Le-Lμ or Le-Lτ gauge bosons, constitute a minimal extension of the standard model that preserves its renormalizability. We study the impact of such interactions on the solar neutrino oscillations when the interaction range RLR is much larger than the Earth-Sun distance. The LR potential can dominate over the standard charged current potential inside the Sun in spite of strong constraints on the coupling α of the LR force coming from the atmospheric neutrino data and laboratory search for new forces. We demonstrate that the solar and atmospheric neutrino mass scales do not get trivially decoupled even if θ13 is vanishingly small. In addition, for α≳10-52 and normal hierarchy, resonant enhancement of θ13 results in nontrivial energy dependent effects on the νe survival probability. We perform a complete three generation analysis, and obtain constraints on α through a global fit to the solar neutrino and KamLAND data. We get the 3σ limits αeμ<3.4×10-53 and αeτ<2.5×10-53 when RLR is much smaller than our distance from the galactic center. With larger RLR, the collective LR potential due to all the electrons in the galaxy becomes significant and the constraints on α become stronger by up to two orders of magnitude.

Chloride Fluxes in Isolated Dialyzed Barnacle Muscle Fibers

PubMed Central

DiPolo, R.

1972-01-01

Chloride outflux and influx has been studied in single isolated muscle fibers from the giant barnacle under constant internal composition by means of a dialysis perfusion technique. Membrane potential was continually recorded. The chloride outfluxes and influxes were 143 and 144 pmoles/cm2-sec (mean resting potential: 58 mv, temperature: 22°–24°C) with internal and external chloride concentrations of 30 and 541 mM, respectively. The chloride conductance calculated from tracer measurements using constant field assumptions is about fourfold greater than that calculated from published electrical data. Replacing 97% of the external chloride ions by propionate reduces the chloride efflux by 51%. Nitrate ions applied either to the internal or external surface of the membrane slows the chloride efflux. The external pH dependence of the chloride efflux follows the external pH dependence of the membrane conductance, in the range pH 3.9–4.7, increasing with decreasing pH. In the range pH 5–9, the chloride efflux increased with increasing pH, in a manner similar to that observed in frog muscle fibers. The titration curve for internal pH changes in the range 4.0–7.0 was quantitatively much different from that for external pH change, indicating significant asymmetry in the internal and external pH dependence of the chloride efflux. PMID:5074810

MEASURING THE LUMINOSITY AND VIRIAL BLACK HOLE MASS DEPENDENCE OF QUASAR–GALAXY CLUSTERING AT z ∼ 0.8

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

Krolewski, Alex G.; Eisenstein, Daniel J., E-mail: akrolewski@college.harvard.edu

2015-04-10

We study the dependence of quasar clustering on quasar luminosity and black hole mass by measuring the angular overdensity of photometrically selected galaxies imaged by the Wide-field Infrared Survey Explorer (WISE) about z ∼ 0.8 quasars from SDSS. By measuring the quasar–galaxy cross-correlation function and using photometrically selected galaxies, we achieve a higher density of tracer objects and a more sensitive detection of clustering than measurements of the quasar autocorrelation function. We test models of quasar formation and evolution by measuring the luminosity dependence of clustering amplitude. We find a significant overdensity of WISE galaxies about z ∼ 0.8 quasarsmore » at 0.2–6.4 h{sup −1} Mpc in projected comoving separation. We find no appreciable increase in clustering amplitude with quasar luminosity across a decade in luminosity, and a power-law fit between luminosity and clustering amplitude gives an exponent of −0.01 ± 0.06 (1 σ error). We also fail to find a significant relationship between clustering amplitude and black hole mass, although our dynamic range in true mass is suppressed due to the large uncertainties in virial black hole mass estimates. Our results indicate that a small range in host dark matter halo mass maps to a large range in quasar luminosity.« less

Imaging of size-dependent uptake and identification of novel pathways in mouse Peyer's patches using fluorescent organosilica particles.

PubMed

Awaad, Aziz; Nakamura, Michihiro; Ishimura, Kazunori

2012-07-01

We investigated size-dependent uptake of fluorescent thiol-organosilica particles by Peyer's patches (PPs). We performed an oral single-particle administration (95, 130, 200, 340, 695 and 1050 nm) and a simultaneous dual-particle administration using 2 kinds of particles. Histological imaging and quantitative analysis revealed that particles taken up by the PP subepithelial dome were size dependent, and there was an optimal size range for higher uptake. Quantitative analysis of simultaneous dual-particle administration revealed that the percentage of fluorescence areas for 95, 130, 200, 340, 695 and 1050 nm with respect to 110 nm area was 124.0, 89.1, 73.8, 20.2, 9.2 and 0.5%, respectively. Additionally, imaging using fluorescent thiol-organosilica particles could detect 2 novel pathways through mouse PP epithelium: the transcellular pathway and the paracellular pathway. The uptake of nanoparticles based on an optimal size range and 2 novel pathways could indicate a new approach for vaccine delivery and nanomedicine development. Studying various sizes of fluorescent organosilica particles and their uptake in Peyer's patches, this team of authors determined the optimal size range of administration. Two novel pathways through mouse Peyer's patch epithelium were detected, i.e., the transcellular pathway and the paracellular pathway. This observation may have important applications in future vaccine delivery and nano-drug delivery. Copyright © 2012 Elsevier Inc. All rights reserved.

Intramolecular and Lattice Dynamics in V6-nIVVnV O7(OCH3)12 Crystal

NASA Astrophysics Data System (ADS)

Yablokov, Yu. V.; Augustyniak-Jabłokow, M. A.; Borshch, S.; Daniel, C.; Hartl, H.

2006-08-01

Multi-nuclear mixed-valence clusters V4IVV2VO7(OCH3)12 were studied by X-band EPR in the temperature range 4.2-300 K. An isotropic exchange interactions between four VIV ions with individual spin Si=1/2 determine the energy levels structure of the compound with the total spin states S=0, 1, and 2, which are doubled and split due to the extra electron transfer. The spin-Hamiltonian approach was used for the analysis of the temperature dependences of the EPR spectra parameters and the cluster dynamics. Two types of the electron transfer are assumed: the single jump transfer leading to the splitting of the total spin states by intervals comparable in magnitude with the exchange parameter J≈100-150cm-1 and the double jump one resulting in dynamics. The dependence of the transition ratesνtr on the energy of the total spin states was observed. In particular, in the range 300-220 K the νtr ≈0.7×1010 cm-1 and below 180 K the νtr≈1×1010 cm-1 was estimated. The g-factors of the spin states were shown to depend on the values of the intermediate spins. A phase transition in the T-range 210-180 K leading to the change in the initial VIV ions localization was discovered.

Variability in core areas of spider monkeys (Ateles geoffroyi) in a tropical dry forest in Costa Rica.

PubMed

Asensio, Norberto; Schaffner, Colleen M; Aureli, Filippo

2012-04-01

Core areas are highly used parts of the home range on which the survival of solitary or group-living animals depends. We investigated the home range and core area size and area fidelity of a spider monkey community in a tropical dry forest over a 4-year period. Home ranges overlapped extensively across years, subgroup sizes, and seasons. In contrast, spider monkeys used core areas that varied in size and location across the study years, subgroup sizes, and seasons. These shifts in core areas suggest that the understanding of core areas, and thus the spatial requirements, of a species in a particular habitat may be limited if based on short-term studies. In this respect, our findings emphasize the importance of long-term studies of the spatial ecology of any species in a particular habitat. Our study also shows that the yearly home range basically includes all the core areas from different years, seasons, and subgroup sizes (i.e., the super-core area). This is conceptually important for territorial species, such as spider monkeys, which defend a stable home range as it contains not only the current, but also the future core areas.

Measurements and Modeling of III-V Solar Cells at High Temperatures up to 400 $${}^{\\circ}$$ C

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

Perl, Emmett E.; Simon, John; Geisz, John F.

2016-09-01

In this paper, we study the performance of 2.0 eV Al0.12Ga0.39In0.49P and 1.4 eV GaAs solar cells over a temperature range of 25-400 degrees C. The temperature-dependent J01 and J02 dark currents are extracted by fitting current-voltage measurements to a two-diode model. We find that the intrinsic carrier concentration ni dominates the temperature dependence of the dark currents, open-circuit voltage, and cell efficiency. To study the impact of temperature on the photocurrent and bandgap of the solar cells, we measure the quantum efficiency and illuminated current-voltage characteristics of the devices up to 400 degrees C. As the temperature is increased,more » we observe no degradation to the internal quantum efficiency and a decrease in the bandgap. These two factors drive an increase in the short-circuit current density at high temperatures. Finally, we measure the devices at concentrations ranging from ~30 to 1500 suns and observe n = 1 recombination characteristics across the entire temperature range. These findings should be a valuable guide to the design of any system that requires high-temperature solar cell operation.« less

Study of vaporization of sodium metaborate by transpiration thermogravimetry and Knudsen effusion mass spectrometry.

PubMed

Narasimhan, T S Lakshmi; Viswanathan, R; Nalini, S

2011-11-17

The vaporization of solid sodium metaborate NaBO(2)(s) was studied by transpiration thermogravimetry (TTG) and Knudsen effusion mass spectrometry (KEMS). The transpiration measurements, performed for the first time on NaBO(2)(s), involved use of argon as the carrier gas for vapor transport and derivation of vapor pressure of NaBO(2)(g) (by assuming it as the sole vapor species) through many flow-dependence runs and temperature-dependence runs in the temperature range 1075-1218 K. The KEMS measurements performed in the temperature range 1060-1185 K confirmed NaBO(2)(g) as the principal vapor species over NaBO(2)(s), in accord with the previously reported KEMS studies. The values of p(NaBO(2)) obtained by both TTG and KEMS are consistent within the uncertainties associated with each method and so are the second- and third-law values of enthalpy of sublimation, the latter aspect consistently missing in all previous vaporization studies. The results of both TTG and KEMS were combined to recommend the following thermodynamic parameters pertinent to the sublimation reaction, NaBO(2)(s) = NaBO(2)(g): Log{p(NaBO(2))/Pa} = -(17056 ± 441)/(T/K) + (14.73 ± 0.35) for the temperature range 1060-1218 K; Δ(r)H°(m)(298.15 K) = (346.3 ± 9.4) kJ·mol(-1); and Δ(r)S°(m)(298.15 K) = (210.2 ± 6.8) J·mol(-1)·K(-1).

Pharmacological approaches to methamphetamine dependence: a focused review.

PubMed

Karila, Laurent; Weinstein, Aviv; Aubin, Henri-Jean; Benyamina, Amine; Reynaud, Michel; Batki, Steven L

2010-06-01

Methamphetamine dependence is a serious worldwide public health problem with major medical, psychiatric, socioeconomic and legal consequences. Various neuronal mechanisms implicated in methamphetamine dependence have suggested several pharmacological approaches. A literature search from a range of electronic databases (PubMed, EMBASE, PsycInfo, the NIDA research monograph index and the reference list of clinicaltrials.gov) was conducted for the period from January 1985 to October 2009. There were no restrictions on the identification or inclusion of studies in terms of publication status, language and design type. A variety of medications have failed to show efficacy in clinical trials, including a dopamine partial agonist (aripiprazole), GABAergic agents (gabapentin) and serotonergic agents (SSRI, ondansetron, mirtazapine). Three double-blind placebo-controlled trials using modafinil, bupropion and naltrexone have shown positive results in reducing amphetamine or methamphetamine use. Two studies employing agonist replacement medications, one with d-amphetamine and the other with methylphenidate, have also shown promise. Despite the lack of success in most studies to date, increasing efforts are being made to develop medications for the treatment of methamphetamine dependence and several promising agents are targets of further research.

Modelling the physical properties of glasslike carbon foams

NASA Astrophysics Data System (ADS)

Letellier, M.; Macutkevic, J.; Bychanok, D.; Kuzhir, P.; Delgado-Sanchez, C.; Naguib, H.; Ghaffari Mosanenzadeh, S.; Fierro, V.; Celzard, A.

2017-07-01

In this work, model alveolar materials - carbon cellular and/or carbon reticulated foams - were produced in order to study and to model their physical properties. It was shown that very different morphologies could be obtained whereas the constituting vitreous carbon from which they were made remained exactly the same. Doing so, the physical properties of these foams were expected to depend neither on the composition nor on the carbonaceous texture but only on the porous structure, which could be tuned for the first time for having a constant pore size in a range of porosities, or a range of pore sizes at fixed porosity. The physical properties were then investigated through mechanical, acoustic, thermal and electromagnetic measurements. The results demonstrate the roles played by bulk density and cell size on all physical properties. Whereas some of the latter strongly depend on porosity and/or pore size, others are independent of pore size. It is expected that these results apply to many other kinds of rigid foams used in a broad range of different applications. The present results therefore open the route to their optimisation.

Analysis of opioid efficacy, tolerance, addiction and dependence from cell culture to human

PubMed Central

Morgan, Michael M; Christie, MacDonald J

2011-01-01

Opioid agonists are the most effective treatment for pain, but their use is limited by side effects, tolerance and fears of addiction and dependence. A major goal of opioid research is to develop agonists that have high analgesic efficacy and a low profile for side effects, tolerance, addiction and dependence. Unfortunately, there is a serious lack of experimental data comparing the degree to which different opioids produce these effects in humans. In contrast, a wide range of experimental techniques from heterologous expression systems to behaviour assessment in whole animals have been developed to study these problems. The objective of this review is to describe and evaluate these techniques as they are used to study opioid efficacy, tolerance, addiction and dependence. LINKED ARTICLES This article is part of a themed issue on Translational Neuropharmacology. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2011.164.issue-4 PMID:21434879

The refractive index of human hemoglobin in the visible range.

PubMed

Zhernovaya, O; Sydoruk, O; Tuchin, V; Douplik, A

2011-07-07

Because the refractive index of hemoglobin in the visible range is sensitive to the hemoglobin concentration, optical investigations of hemoglobin are important for medical diagnostics and treatment. Direct measurements of the refractive index are, however, challenging; few such measurements have previously been reported, especially in a wide wavelength range. We directly measured the refractive index of human deoxygenated and oxygenated hemoglobin for nine wavelengths between 400 and 700 nm for the hemoglobin concentrations up to 140 g l(-1). This paper analyzes the results and suggests a set of model functions to calculate the refractive index depending on the concentration. At all wavelengths, the measured values of the refractive index depended on the concentration linearly. Analyzing the slope of the lines, we determined the specific refraction increments, derived a set of model functions for the refractive index depending on the concentration, and compared our results with those available in the literature. Based on the model functions, we further calculated the refractive index at the physiological concentration within the erythrocytes of 320 g l(-1). The results can be used to calculate the refractive index in the visible range for arbitrary concentrations provided that the refractive indices depend on the concentration linearly.

Broadband nanoindentation of glassy polymers: Part II. Viscoplasticity

Treesearch

Joseph E. Jakes; Rod S. Lakes; Don S. Stone

2012-01-01

The relationship between hardness and flow stress in glassy polymers is examined. Materials studied include poly(methylmethacrylate), polystyrene, and polycarbonate. Properties are strongly rate dependent, so broadband nanoindentation creep (BNC) is used to measure hardness across a broad range of indentation strain rates (10-4 to 10 s

Statistical behavior of the tensile property of heated cotton fiber

USDA-ARS?s Scientific Manuscript database

The temperature dependence of the tensile property of single cotton fiber was studied in the range of 160-300°C using Favimat test, and its statistical behavior was interpreted in terms of structural changes. The tenacity of control cotton fiber was well described by the single Weibull distribution,...

Development and application of a density dependent matrix population model for Atlantic killifish (Fundulus heteroclitus)

EPA Science Inventory

Ranging along the Atlantic coast from US Florida to the Maritime Provinces of Canada, the Atlantic killifish (Fundulus heteroclitus) is an important and well-studied model organism for understanding the effects of pollutants and other stressors in estuarine and marine ecosystems....

Perceived Parenting

ERIC Educational Resources Information Center

Wouters, Sofie; Doumen, Sarah; Germeijs, Veerle; Colpin, Hilde; Verschueren, Karine

2013-01-01

Contingent self-esteem (i.e., the degree to which one's self-esteem is dependent on meeting particular conditions) has been shown to predict a wide range of psychosocial and academic problems. This study extends previous research on contingent self-esteem by examining the predictive role of perceived parenting dimensions in a sample of early…

Pre-Service Primary Teachers' Attitudes towards Inclusive Education

ERIC Educational Resources Information Center

Varcoe, Linda; Boyle, Christopher

2014-01-01

Research has demonstrated that an important factor in the success of inclusive education is dependent upon teachers' attitudes. Based on this evidence, the present study investigated the impact of a range of teacher variables in association with training on primary pre-service teachers' attitudes by examining total inclusion scores, positive…

Children's Mappings of Large Number Words to Numerosities

ERIC Educational Resources Information Center

Barth, Hilary; Starr, Ariel; Sullivan, Jessica

2009-01-01

Previous studies have suggested that children's learning of the relation between number words and approximate numerosities depends on their verbal counting ability, and that children exhibit no knowledge of mappings between number words and approximate numerical magnitudes for number words outside their productive verbal counting range. In the…

Temperature-dependent biological and demographic parameters of Coleomegilla maculata (Coleoptera: Coccinellidae)

USDA-ARS?s Scientific Manuscript database

The temperature requirements for development and the optimal range of temperatures for growth and reproduction of Coleomegilla maculata De Geer were studied. The development time of individual C. maculata larvae were determined at 18, 21, 24, 27, 30, 33, and 36°C. Development times were converted to...

Multi-dynamic range compressional wave detection using optical-frequency comb

NASA Astrophysics Data System (ADS)

Minamikawa, Takeo; Masuoka, Takashi; Oe, Ryo; Nakajima, Yoshiaki; Yamaoka, Yoshihisa; Minoshima, Kaoru; Yasui, Takeshi

2018-02-01

Compressional wave detection is useful means for health monitoring of building, detection of abnormal vibration of moving objects, defect evaluation, and biomedical imaging such as echography and photoacoustic imaging. The frequency of the compressional wave is varied from quasi-static to a few tens of megahertz depending on applications. Since the dynamic range of general compressional wave detectors is limited, we need to choose a proper compressional wave detector depending on applications. For the compressional wave detection with wide dynamic range, two or more detectors with different detection ranges is required. However, these detectors with different detection ranges generally has different accuracy and precision, disabling the seamless detection over these detection ranges. In this study, we proposed a compressional wave detector employing optical frequency comb (OFC). The compressional wave was sensed with a part of an OFC cavity, being encoded into OFC. The spectrally encoded OFC was converted to radio-frequency by the frequency link nature of OFC. The compressional wave-encoded radio-frequency can therefore be directly measured with a high-speed photodetector. To enhance the dynamic range of the compressional wave detection, we developed a cavityfeedback-based system and a phase-sensitive detection system, both of which the accuracy and precision are coherently linked to these of the OFC. We provided a proof-of-principle demonstration of the detection of compressional wave from quasi-static to ultrasound wave by using the OFC-based compressional wave sensor. Our proposed approach will serve as a unique and powerful tool for detecting compressional wave versatile applications in the future.

Optical properties of InGaN thin films in the entire composition range

NASA Astrophysics Data System (ADS)

Kazazis, S. A.; Papadomanolaki, E.; Androulidaki, M.; Kayambaki, M.; Iliopoulos, E.

2018-03-01

The optical properties of thick InGaN epilayers, with compositions spanning the entire ternary range, are studied in detail. High structural quality, single phase InxGa1-xN (0001) films were grown heteroepitaxially by radio-frequency plasma assisted molecular-beam epitaxy on freestanding GaN substrates. Their emission characteristics were investigated by low temperature photoluminescence spectroscopy, whereas variable angle spectroscopic ellipsometry was applied to determine the complex dielectric function of the films, in the 0.55-4.0 eV photon range. Photoluminescence lines were intense and narrow, in the range of 100 meV for Ga-rich InGaN films (x < 0.3), around 150 meV for mid-range composition films (0.3 < x < 0.6), and in the range of 50 meV for In-rich alloys (x > 0.6). The composition dependence of the strain-free emission energy was expressed by a bowing parameter of b = 2.70 ± 0.12 eV. The films' optical dielectric function dispersion was obtained by the analysis of the ellipsometric data employing a Kramers-Kronig consistent parameterized optical model. The refractive index dispersion was obtained for alloys in the entire composition range, and the corresponding values at the band edge show a parabolic dependence on the InN mole fraction expressed by a bowing parameter of b = 0.81 ± 0.04. The bowing parameter describing the fundamental energy bandgap was deduced to be equal to 1.66 ± 0.07 eV, consistent with the ab initio calculations for statistically random (non-clustered) InGaN alloys.

Long-range electrostatic screening in ionic liquids

PubMed Central

Gebbie, Matthew A.; Dobbs, Howard A.; Valtiner, Markus; Israelachvili, Jacob N.

2015-01-01

Electrolyte solutions with high concentrations of ions are prevalent in biological systems and energy storage technologies. Nevertheless, the high interaction free energy and long-range nature of electrostatic interactions makes the development of a general conceptual picture of concentrated electrolytes a significant challenge. In this work, we study ionic liquids, single-component liquids composed solely of ions, in an attempt to provide a novel perspective on electrostatic screening in very high concentration (nonideal) electrolytes. We use temperature-dependent surface force measurements to demonstrate that the long-range, exponentially decaying diffuse double-layer forces observed across ionic liquids exhibit a pronounced temperature dependence: Increasing the temperature decreases the measured exponential (Debye) decay length, implying an increase in the thermally driven effective free-ion concentration in the bulk ionic liquids. We use our quantitative results to propose a general model of long-range electrostatic screening in ionic liquids, where thermally activated charge fluctuations, either free ions or correlated domains (quasiparticles), take on the role of ions in traditional dilute electrolyte solutions. This picture represents a crucial step toward resolving several inconsistencies surrounding electrostatic screening and charge transport in ionic liquids that have impeded progress within the interdisciplinary ionic liquids community. More broadly, our work provides a previously unidentified way of envisioning highly concentrated electrolytes, with implications for diverse areas of inquiry, ranging from designing electrochemical devices to rationalizing electrostatic interactions in biological systems. PMID:26040001

pH-dependent Differential Scanning Calorimetry and Dynamic Light Scattering Studies of 21:0 PC and 18:0 PS Lipid Binary System

NASA Astrophysics Data System (ADS)

Ali, Rejwan

2010-03-01

Large unilamallar vesicle has been a model system to study many membrane functions. High Tg lipid systems offer many potential biomedical applications in lipid-based delivery applications. While the optimized vesicle functionalities are achieved by Polyethylene Glycol (PEG) polymer, modified PEG and other functional molecule incorporation, however, the host binary lipid system plays the pivotal role in pH-dependent phase transition based lipid vehicular methods. We have investigated a lipid binary system composed of 21:0 PC (1,2-dihenarachidoyl-sn-glycero-3-phosphocholine) and 18:0 PS(1,2-distearoyl-sn-glycero-3-phospho-L-serine). Preliminary studies implementing differential scanning calorimetry shows pH plays key role in temperature shift and thermotropic phase behavior of the binary system. While dynamic light scattering study shows lipid vesicle size is almost independent of pH changes. We will also present pH-dependent thermodynamic parameters to correlate underlying molecular mechanism in relevant pH-range.

Effect of the product type, of the amount of applied sunscreen product and the level of protection in the UVB range on the level of protection achieved in the UVA range.

PubMed

Couteau, C; Diarra, H; Coiffard, L

2016-03-16

Using a topical product is part of the overall strategy for skin cancer prevention. The level of protection attainable when using commercial products is indicated by the Sun Protection Factor (SPF) value, in use everywhere. This value reflects the level of protection primarily in the UVB range. However, UVA radiation also has deleterious effects on the skin, and it is essential to prevent it, which is why products must offer a wide spectrum of protection. Tests conducted in vivo, before any marketing, are done by applying the studied product at a rate of 2.0 mg cm(-2), while users, in practice, only use 1.0-1.5 mg cm(-2). We now know that this reduction in the amount of applied product greatly affects the SPF. To complete the state of knowledge in this area, we sought to evaluate the effect of a decrease in the amount of applied sunscreen product by studying sunscreen creams and oils on the level of protection attainable in the UVA range. We have shown that the PF-UVA is divided by a factor of 2.2, on average, when the amount of applied product is reduced by half, with differences depending on the product type under consideration (cream or oil) and depending on the SPF of the preparation. Copyright © 2016 Elsevier B.V. All rights reserved.

Directionality of dog vocalizations

NASA Astrophysics Data System (ADS)

Frommolt, Karl-Heinz; Gebler, Alban

2004-07-01

The directionality patterns of sound emission in domestic dogs were measured in an anechoic environment using a microphone array. Mainly long-distance signals from four dogs were investigated. The radiation pattern of the signals differed clearly from an omnidirectional one with average differences in sound-pressure level between the frontal and rear position of 3-7 dB depending from the individual. Frequency dependence of directionality was shown for the range from 250 to 3200 Hz. The results indicate that when studying acoustic communication in mammals, more attention should be paid to the directionality pattern of sound emission.

Measure-valued solutions to nonlocal transport equations on networks

NASA Astrophysics Data System (ADS)

Camilli, Fabio; De Maio, Raul; Tosin, Andrea

2018-06-01

Aiming to describe traffic flow on road networks with long-range driver interactions, we study a nonlinear transport equation defined on an oriented network where the velocity field depends not only on the state variable but also on the distribution of the population. We prove existence, uniqueness and continuous dependence results of the solution intended in a suitable measure-theoretic sense. We also provide a representation formula in terms of the push-forward of the initial and boundary data along the network and discuss an explicit example of nonlocal velocity field fitting our framework.

Temperature dependences of saturated vapor pressure and the enthalpy of vaporization of n-pentyl esters of dicarboxylic acids

NASA Astrophysics Data System (ADS)

Portnova, S. V.; Krasnykh, E. L.; Levanova, S. V.

2016-05-01

The saturated vapor pressures and enthalpies of vaporization of n-pentyl esters of linear C2-C6 dicarboxylic acids are determined by the transpiration method in the temperature range of 309.2-361.2 K. The dependences of enthalpies of vaporization on the number of carbon atoms in the molecule and on the retention indices have been determined. The predictive capabilities of the existing calculation schemes for estimation of enthalpy of vaporization of the studied compounds have been analyzed.

Study of diffusion coefficient of anhydrous trehalose glasses by using PFG-NMR spectroscopy

NASA Astrophysics Data System (ADS)

Kwon, Hyun-Joung; Takekawa, Reiji; Kawamura, Junichi; Tokuyama, Michio

2013-02-01

We investigated the temperature dependent long time self-diffusion coefficient of the anhydrous trehalose supercooled liquids by using pulsed field gradient nuclear magnetic resonance (PFG-NMR) spectroscopy. At the same temperature ranges, the diffusion coefficient convoluted from the α-relaxation time as Einstein-Smoluchowski relaxation, measured by using the dielectric loss spectroscopy are well overlapped with diffusion coefficients within experimental error. The temperature dependent diffusion coefficients obtained from different methods are normalized by fictive temperature and well satisfied the single master curve, proposed by Tokuyama.

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

Song, Young-Ho; Lazauskas, Rimantas; Park, Tae-Sun

M1 properties, comprising magnetic moments and radiative capture of thermal neutron observables, are studied in two- and three-nucleon systems. We use meson exchange current derived up to N{sup 3}LO using heavy baryon chiral perturbation theory a la Weinberg. Calculations have been performed for several qualitatively different realistic nuclear Hamiltonians, which permits us to analyze model dependence of our results. Our results are found to be strongly correlated with the effective range parameters such as binding energies and the scattering lengths. Taking into account such correlations, the results are in good agreement with the experimental data with small model dependence.

Pupil movements to light and accommodative stimulation - A comparative study.

NASA Technical Reports Server (NTRS)

Semmlow, J.; Stark, L.

1973-01-01

Isolation and definition of specific response components in pupil reflexes through comparison of the dynamic features of light-induced and accommodation-induced pupil movements. A quantitative analysis of the behavior of the complex nonlinear pupil responses reveals the presence of two independent nonlinear characteristics: a range-dependent gain and a direction dependence or movement asymmetry. These nonlinear properties are attributed to motor processes because they are observable in pupil responses to both light and accommodation stimuli. The possible mechanisms and consequences of these pupil response characteristics are quantitatively defined and discussed.

Multi-scale simulations of droplets in generic time-dependent flows

NASA Astrophysics Data System (ADS)

Milan, Felix; Biferale, Luca; Sbragaglia, Mauro; Toschi, Federico

2017-11-01

We study the deformation and dynamics of droplets in time-dependent flows using a diffuse interface model for two immiscible fluids. The numerical simulations are at first benchmarked against analytical results of steady droplet deformation, and further extended to the more interesting case of time-dependent flows. The results of these time-dependent numerical simulations are compared against analytical models available in the literature, which assume the droplet shape to be an ellipsoid at all times, with time-dependent major and minor axis. In particular we investigate the time-dependent deformation of a confined droplet in an oscillating Couette flow for the entire capillary range until droplet break-up. In this way these multi component simulations prove to be a useful tool to establish from ``first principles'' the dynamics of droplets in complex flows involving multiple scales. European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No 642069. & European Research Council under the European Community's Seventh Framework Program, ERC Grant Agreement No 339032.

Parasite-mediated interactions within the insect vector: Trypanosoma rangeli strategies.

PubMed

Garcia, Eloi S; Castro, Daniele P; Figueiredo, Marcela B; Azambuja, Patrícia

2012-05-30

Trypanosoma rangeli is a protozoan that is non-pathogenic for humans and other mammals but causes pathology in the genus Rhodnius. T. rangeli and R. prolixus is an excellent model for studying the parasite-vector interaction, but its cycle in invertebrates remains unclear. The vector becomes infected on ingesting blood containing parasites, which subsequently develop in the gut, hemolymph and salivary glands producing short and large epimastigotes and metacyclic trypomastigotes, which are the infective forms. The importance of the T. rangeli cycle is the flagellate penetration into the gut cells and invasion of the salivary glands. The establishment of the parasite depends on the alteration of some vector defense mechanisms. Herein, we present our understanding of T. rangeli infection on the vector physiology, including gut and salivary gland invasions, hemolymph reactions and behavior alteration.

Vivid structural colors with low angle dependence from long-range ordered photonic crystal films.

PubMed

Su, Xin; Xia, Hongbo; Zhang, Shufen; Tang, Bingtao; Wu, Suli

2017-03-02

Structural colored materials have attracted increasing attention due to their vivid color effects and non-photobleaching characteristics. However, the angle dependence of these structural colors severely restricts their practical applications, for example, in display and sensing devices. Here, a new strategy for obtaining low angle dependent structural colors is demonstrated by fabricating long-range ordered photonic crystal films. By using spheres with high refractive indices as building blocks, the angle dependence of the obtained colors has been strongly suppressed. Green, golden yellow and red structural colored films with low angle dependence were obtained by using 145 nm, 165 nm and 187 nm Cu 2 O spheres as building blocks, respectively. SEM images confirmed the long-range highly ordered arrays of the Cu 2 O photonic crystal films. Reflectance spectra and digital photographs clearly demonstrate the low angle dependence of these structural colors, which is in sharp comparison with the case of polystyrene (PS) and SiO 2 photonic crystal films. Furthermore, these structural colors are vivid with high color saturation, not only under black background, but also under white background and natural light without adding any light-absorbing agents. These low angle dependent structural colors endow Cu 2 O photonic crystal films with great potential in practical applications. Our findings may broaden the strategies for the design and fabrication of angle independent structural colored materials.

Orbital-dependent Electron-Hole Interaction in Graphene and Associated Multi-Layer Structures

PubMed Central

Deng, Tianqi; Su, Haibin

2015-01-01

We develop an orbital-dependent potential to describe electron-hole interaction in materials with structural 2D character, i.e. quasi-2D materials. The modulated orbital-dependent potentials are also constructed with non-local screening, multi-layer screening, and finite gap due to the coupling with substrates. We apply the excitonic Hamiltonian in coordinate-space with developed effective electron-hole interacting potentials to compute excitons’ binding strength at M (π band) and Γ (σ band) points in graphene and its associated multi-layer forms. The orbital-dependent potential provides a range-separated property for regulating both long- and short-range interactions. This accounts for the existence of the resonant π exciton in single- and bi-layer graphenes. The remarkable strong electron-hole interaction in σ orbitals plays a decisive role in the existence of σ exciton in graphene stack at room temperature. The interplay between gap-opening and screening from substrates shed a light on the weak dependence of σ exciton binding energy on the thickness of graphene stacks. Moreover, the analysis of non-hydrogenic exciton spectrum in quasi-2D systems clearly demonstrates the remarkable comparable contribution of orbital dependent potential with respect to non-local screening process. The understanding of orbital-dependent potential developed in this work is potentially applicable for a wide range of materials with low dimension. PMID:26610715

Predictors of moderated drinking in a primarily alcohol dependent sample of men who have sex with men

PubMed Central

Kuerbis, Alexis; Morgenstern, Jon; Hail, Lisa

2012-01-01

Understanding for whom moderated drinking is a viable, achievable, and sustainable goal among those with a range of alcohol use disorders (AUD) remains an important public health question. Despite common acceptance as severe risk factors, there is little empirical evidence to conclude whether co-occurring mental health disorders or drug dependence contribute to an individual’s inability to successfully moderate his drinking. Utilizing secondary data analysis, the purpose of this study was to identify predictors of moderation among both treatment seeking and non-treatment seeking, primarily alcohol dependent, problem drinking men who have sex with men (MSM), with an emphasis on the high risk factors psychiatric comorbidity and drug dependence. Problem drinkers (N=187) were assessed, provided feedback about their drinking, given the option to receive brief AUD treatment or change their drinking on their own, and then followed for 15 months. Findings revealed that neither psychiatric comorbidity or drug dependence predicted ability to achieve moderation when controlling for alcohol dependence severity. Those who were younger, more highly educated, and had more mild alcohol dependence were more likely to achieve moderated drinking. Impact of treatment on predictors is explored. Limitations of this study and arenas for future research are discussed. PMID:22201219

Prediction of Viking lander camera image quality

NASA Technical Reports Server (NTRS)

Huck, F. O.; Burcher, E. E.; Jobson, D. J.; Wall, S. D.

1976-01-01

Formulations are presented that permit prediction of image quality as a function of camera performance, surface radiance properties, and lighting and viewing geometry. Predictions made for a wide range of surface radiance properties reveal that image quality depends strongly on proper camera dynamic range command and on favorable lighting and viewing geometry. Proper camera dynamic range commands depend mostly on the surface albedo that will be encountered. Favorable lighting and viewing geometries depend mostly on lander orientation with respect to the diurnal sun path over the landing site, and tend to be independent of surface albedo and illumination scattering function. Side lighting with low sun elevation angles (10 to 30 deg) is generally favorable for imaging spatial details and slopes, whereas high sun elevation angles are favorable for measuring spectral reflectances.

Dependence of average inter-particle distance upon the temperature of neutrals in dusty plasma crystals

NASA Astrophysics Data System (ADS)

Nikolaev, V. S.; Timofeev, A. V.

2018-01-01

It is often suggested that inter-particle distance in stable dusty plasma structures decreases with cooling as a square root of neutral gas temperature. Deviations from this dependence (up to the increase at cryogenic temperatures) found in the experimental results for the pressures range 0.1-8.0 mbar and for the currents range 0.1-1.0 mA are given. Inter-particle distance dependences on the charge of particles, parameter of the trap and the screening length in surrounding plasma are obtained for different conditions from molecular dynamics simulations. They are well approximated by power functions in the mentioned range of parameters. It is found that under certain assumptions thermophoretical force is responsible for inter-particle distance increase at cryogenic temperatures.

Clinical and electrophysiological characteristics of patients with paroxysmal intra-His block with narrow QRS complexes.

PubMed

Ragupathi, Loheetha; Johnson, Drew; Greenspon, Arnold; Frisch, Daniel; Ho, Reginald T; Pavri, Behzad B

2018-04-18

Atrioventricular (AV) block is usually due to infranodal disease and associated with a wide QRS complex; such patients often progress to complete AV block and pacemaker dependency. Uncommonly, infranodal AV block can occur within the His bundle with a narrow QRS complex. The aims of this study were to define clinical/echocardiographic characteristics of patients with AV block within the His bundle and report progression to pacemaker dependency. We retrospectively identified patients with narrow QRS complexes and documented intra-His delay or block at electrophysiology study (group A) or with electrocardiogram-documented Mobitz II AV block/paroxysmal AV block (group B). Clinical, electrophysiological, and echocardiographic variables at presentation and pacemaker parameters at the last follow-up visit were evaluated. Twenty-seven patients (19 women) were identified (mean age 64 ± 13 years; range, 38-85 years). Four patients who had <1 month of follow-up were excluded. There were 12 patients in group A and 11 in group B; 21 of 23 presented with syncope/presyncope. All patients received pacemakers: 8 single chamber and 15 dual chamber. After a median follow-up of 6.4 years, the median percentage of ventricular pacing was 1% (interquartile range 0%-4.66%). One patient developed true pacemaker dependency. Aortic and/or mitral annular calcification was present in 13 of 22 patients with available echocardiograms. Patients who present with syncope and narrow QRS complexes with intra-His delay or Mobitz II paroxysmal AV block with narrow QRS complexes rarely progress to pacemaker dependency and require infrequent pacing. This entity is more common in women, with a higher prevalence of aortic and/or mitral annular calcification. If confirmed by additional studies, single-chamber pacemaker may be sufficient. Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Crustal attenuation characteristics in western Turkey

NASA Astrophysics Data System (ADS)

Kurtulmuş, Tevfik Özgür; Akyol, Nihal

2013-11-01

We analysed 1764 records produced by 322 micro- and moderate-size local earthquakes in western Turkey to estimate crustal attenuation characteristics in the frequency range of 1.0 ≤ f ≤ 10 Hz. In the first step, we obtained non-parametric attenuation functions and they show that seismic recordings of transverse and radial S waves exhibit different characteristics at short and long hypocentral distances. Applying a two-step inversion, we parametrized Q( f ) and geometrical spreading exponent b( f ) for the entire distance range between 10 and 200 km and then we estimated separately Q and b values for short (10-70 km) and large (120-200 km) distance ranges. We could not observe significant frequency dependencies of b for short distance range, whereas the significant frequency dependence of b was observed for large distances. Low Q0 values (˜60) with strong frequency dependence of Q (˜1.4) for short distances suggest that scattering might be an important factor contributing to the attenuation of body waves in the region, which could be associated to a high degree of fracturing, fluid filled cracks, young volcanism and geothermal activity in the crust. Weak Q frequency dependence and higher Q0 values for large distances manifest more homogenous medium because of increasing pressure and enhanced healing of cracks with increasing temperature and depth. Q anisotropy was also observed for large hypocentral distance ranges.

Kinetic studies of a doubly bound red cell antigen-antibody system.

PubMed

Oberhardt, B J; Miller, I F

1972-08-01

The Polybrene method for detection of red cell antibodies which utilizes continuous flow equipment was modified so that kinetic studies could be performed on red cell antibodies doubly bound between adjacent red cells. In the anti-Rh(o)-Rh(o) erythrocyte system, deaggregation by temperature was studied over an antibody concentration range of from approximately 1 to 500 antibody molecules per erythrocyte, a residence time range of approximately eightfold, and a temperature range of from 10 to 55 degrees C. The rate of dissociation of antigen-antibody complex, as determined from deaggregation of antibody-dependent red cell aggregates, was found to be of apparent zero order. The apparent activation energy for the antigen-antibody reaction under the experimental conditions was determined and found to be higher than would be expected for singly bound antigen-antibody systems. Possible explanations are considered for these findings in terms of an antigen-antibody bond-breaking model.

Effect of smectic A temperature width on the soft mode in ferroelectric liquid crystals

NASA Astrophysics Data System (ADS)

Choudhary, A.; Kaur, S.; Prakash, J.; Sreenivas, K.; Bawa, S. S.; Biradar, A. M.

2008-08-01

The behavior of soft mode range with respect to the temperature width of smectic A (Sm A) phase has been studied in four different ferroelectric liquid crystal (FLC) materials in the frequency range 10Hz-10MHz. The studies have been carried out in a planarly well aligned cells at different temperatures and different bias fields in Sm C* and Sm A phases. Dielectric studies of these FLCs near Sm C*-Sm A phase transition show that the temperature range of soft mode relaxation frequency phenomenon varies with the temperature width of Sm A phase. The dependence of tilt angle on temperature shows the nature of the order of transition at Sm C*-Sm A phase. The coupling between order parameters of Sm C* and Sm A phase influences the soft mode and phase transition in Sm C* and Sm A phases.

Dielectric relaxation studies in Se{sub 90}Cd{sub 8}Sb{sub 2} glassy alloy

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

Shukla, Nitesh; Rao, Vandita; Dwivedi, D. K.

2016-05-06

Se{sub 90}Cd{sub 8}Sb{sub 2} chalcogenide semiconducting alloy was prepared by melt quench technique. The prepared glassy alloy has been characterized by techniques such as scanning electron microscopy (SEM) and energy dispersive X-ray (EDAX).Dielectric properties of Se{sub 90}Cd{sub 8}Sb{sub 2} chalcogenide semiconductor have been studied using impedance spectroscopic technique in the frequency range 5×10{sup 2}Hz - 1×10{sup 5}Hz and in temperature range 303-318K. It is found that dielectric constant ε′ and dielectric loss factor ε″ are dependent on frequency and temperature.

Reliability analysis of interdependent lattices

NASA Astrophysics Data System (ADS)

Limiao, Zhang; Daqing, Li; Pengju, Qin; Bowen, Fu; Yinan, Jiang; Zio, Enrico; Rui, Kang

2016-06-01

Network reliability analysis has drawn much attention recently due to the risks of catastrophic damage in networked infrastructures. These infrastructures are dependent on each other as a result of various interactions. However, most of the reliability analyses of these interdependent networks do not consider spatial constraints, which are found important for robustness of infrastructures including power grid and transport systems. Here we study the reliability properties of interdependent lattices with different ranges of spatial constraints. Our study shows that interdependent lattices with strong spatial constraints are more resilient than interdependent Erdös-Rényi networks. There exists an intermediate range of spatial constraints, at which the interdependent lattices have minimal resilience.

The influence of liquidity on informational efficiency: The case of the Thai Stock Market

NASA Astrophysics Data System (ADS)

Bariviera, Aurelio Fernández

2011-11-01

The presence of long-range memory in financial time series is a puzzling fact that challenges the established financial theory. We study the effect of liquidity on the efficiency (measured by the Hurst’s exponent) of the Thai Stock Market. According to our study, we find that: (i) the R/S method could generate spurious long-range dependence, giving the DFA method more reliable estimates of the Hurst’s exponent and (ii) there is a weak relationship between market capitalization and the efficiency of the market, and that the latter is not significantly affected by the presence of foreign investors.

Alprazolam use and dependence. A retrospective analysis of 30 cases of withdrawal.

PubMed Central

Dickinson, B; Rush, P A; Radcliffe, A B

1990-01-01

From 1986 to 1989, the Chemical Dependency Recovery Program at Kaiser Permanente Hospital, Fontana, California, admitted an increasing number of patients for alprazolam dependence. Severe withdrawal reactions and adverse consequences with use were reported in the literature. In this review of 30 cases of alprazolam dependence and subsequent withdrawal, there was a statistically significant increase in the number of patient hospital days, the subjective symptoms, and staff time spent with patients compared with those in alcoholic controls. Most patients with diagnosed alprazolam dependence used doses in the range recommended by the package information at the time of admission. Patients with low preadmission doses of 1 mg or less per day showed notable withdrawal symptoms. The average duration of use was 29.9 months, considerably longer than suggested effective ranges. Most patients (28) had a chemical dependence history before being placed on alprazolam therapy; 24 had a positive family history of chemical dependence; and 24 had previous or current psychiatric care. PMID:2349800

Temperature and pressure dependences of kimberlite melts viscosity (experimental-theoretical study)

NASA Astrophysics Data System (ADS)

Persikov, Eduard; Bykhtiyarov, Pavel; Cokol, Alexsander

2016-04-01

Experimental data on temperature and pressure dependences of viscosity of model kimberlite melts (silicate 82 + carbonate 18, wt. %, 100NBO/T = 313) have been obtained for the first time at 100 MPa of CO2 pressure and at the lithostatic pressures up to 7.5 GPa in the temperature range 1350 oC - 1950 oC using radiation high gas pressure apparatus and press free split-sphere multi - anvil apparatus (BARS). Experimental data obtained on temperature and pressure dependences of viscosity of model kimberlite melts at moderate and high pressures is compared with predicted data on these dependences of viscosity of basaltic melts (100NBO/T = 58) in the same T, P - range. Dependences of the viscosity of model kimberlite and basaltic melts on temperature are consistent to the exponential Arrenian equation in the T, P - range of experimental study. The correct values of activation energies of viscous flow of kimberlite melts have been obtained for the first time. The activation energies of viscous flow of model kimberlite melts exponentially increase with increasing pressure and are equal: E = 130 ± 1.3 kJ/mole at moderate pressure (P = 100 MPa) and E = 160 ± 1.6 kJ/mole at high pressure (P = 5.5 GPa). It has been established too that the viscosity of model kimberlite melts exponentially increases on about half order of magnitude with increasing pressures from 100 MPa to 7.5 GPa at the isothermal condition (1800 oC). It has been established that viscosity of model kimberlite melts at the moderate pressure (100 MPa) is lover on about one order of magnitude to compare with the viscosity of basaltic melts, but at high pressure range (5.5 - 7.5 GPa), on the contrary, is higher on about half order of magnitude at the same values of the temperatures. Here we use both a new experimental data on viscosity of kimberlite melts and our structural chemical model for calculation and prediction the viscosity of magmatic melts [1] to determine the fundamental features of viscosity of kimberlite and basaltic magmas at the T, P - parameters of the Earth's crust and upper mantle. The Russian Foundation for Basic Research (project 15-05-01318) and the Russian Science Foundation (project 14-27-00054) are acknowledged for the financial support. [1] Persikov, E.S. & Bukhtiyarov, P.G. (2009) Russian Geology & Geophysics, 50, No 12, 1079-1090.

Gravity-Driven Thin Film Flow of an Ellis Fluid.

PubMed

Kheyfets, Vitaly O; Kieweg, Sarah L

2013-12-01

The thin film lubrication approximation has been studied extensively for moving contact lines of Newtonian fluids. However, many industrial and biological applications of the thin film equation involve shear-thinning fluids, which often also exhibit a Newtonian plateau at low shear. This study presents new numerical simulations of the three-dimensional (i.e. two-dimensional spreading), constant-volume, gravity-driven, free surface flow of an Ellis fluid. The numerical solution was validated with a new similarity solution, compared to previous experiments, and then used in a parametric study. The parametric study centered around rheological data for an example biological application of thin film flow: topical drug delivery of anti-HIV microbicide formulations, e.g. hydroxyethylcellulose (HEC) polymer solutions. The parametric study evaluated how spreading length and front velocity saturation depend on Ellis parameters. A lower concentration polymer solution with smaller zero shear viscosity ( η 0 ), τ 1/2 , and λ values spread further. However, when comparing any two fluids with any possible combinations of Ellis parameters, the impact of changing one parameter on spreading length depends on the direction and magnitude of changes in the other two parameters. In addition, the isolated effect of the shear-thinning parameter, λ , on the front velocity saturation depended on τ 1/2 . This study highlighted the relative effects of the individual Ellis parameters, and showed that the shear rates in this flow were in both the shear-thinning and plateau regions of rheological behavior, emphasizing the importance of characterizing the full range of shear-rates in rheological measurements. The validated numerical model and parametric study provides a useful tool for future steps to optimize flow of a fluid with rheological behavior well-described by the Ellis constitutive model, in a range of industrial and biological applications.

A study of coherence of soft gluons in hadron jets

NASA Astrophysics Data System (ADS)

Akrawy, M. Z.; Alexander, G.; Allison, J.; Allport, P. P.; Anderson, K. J.; Armitage, J. C.; Arnison, G. T. J.; Ashton, P.; Azuelos, G.; Baines, J. T. M.; Ball, A. H.; Banks, J.; Barker, G. J.; Barlow, R. J.; Batley, J. R.; Becker, J.; Behnke, T.; Bell, K. W.; Bella, G.; Bethke, S.; Biebel, O.; Binder, U.; Bloodworth, I. J.; Bock, P.; Breuker, H.; Brown, R. M.; Brun, R.; Buijs, A.; Burckhart, H. J.; Capiluppi, P.; Carnegie, R. K.; Carter, A. A.; Carter, J. R.; Chang, C. Y.; Charlton, D. G.; Chrin, J. T. M.; Clarke, P. E. L.; Cohen, I.; Collins, W. J.; Conboy, J. E.; Couch, M.; Coupland, M.; Cuffiani, M.; Dado, S.; Dallavalle, G. M.; Debu, P.; Deninno, M. M.; Dieckmann, A.; Dittmar, M.; Dixit, M. S.; Duchovni, E.; Duerdoth, I. P.; Dumas, D. J. P.; El Mamouni, H.; Elcombe, P. A.; Estabrooks, P. G.; Etzion, E.; Fabbri, F.; Farthouat, P.; Fischer, H. M.; Fong, D. G.; French, M. T.; Fukunaga, C.; Gaidot, A.; Ganel, O.; Gary, J. W.; Gascon, J.; Geddes, N. I.; Gee, C. N. P.; Geich-Gimbel, C.; Gensler, S. W.; Gentit, F. X.; Giacomelli, G.; Gibson, V.; Gibson, W. R.; Gillies, J. D.; Goldberg, J.; Goodrick, M. J.; Gorn, W.; Granite, D.; Gross, E.; Grunhaus, J.; Hagedorn, H.; Hagemann, J.; Hansroul, M.; Hargrove, C. K.; Harrus, I.; Hart, J.; Hattersley, P. M.; Hauschild, M.; Hawkes, C. M.; Heflin, E.; Hemingway, R. J.; Heuer, R. D.; Hill, J. C.; Hillier, S. J.; Ho, C.; Hobbs, J. D.; Hobson, P. R.; Hochman, D.; Holl, B.; Homer, R. J.; Hou, S. R.; Howarth, C. P.; Hughes-Jones, R. E.; Humbert, R.; Igo-Kemenes, P.; Ihssen, H.; Imrie, D. C.; Jawahery, A.; Jeffreys, P. W.; Jeremie, H.; Jimack, M.; Jobes, M.; Jones, R. W. L.; Jovanovic, P.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Kellogg, R. G.; Kennedy, B. W.; Kleinwort, C.; Klem, D. E.; Knop, G.; Kobayashi, T.; Kokott, T. P.; Köpke, L.; Kowalewski, R.; Kreutzmann, H.; Kroll, J.; Kuwano, M.; Kyberd, P.; Lafferty, G. D.; Lamarche, F.; Larson, W. J.; Layter, J. G.; Le Du, P.; Leblanc, P.; Lee, A. M.; Lehto, M. H.; Lellouch, D.; Lennert, P.; Lessard, L.; Levinson, L.; Lloyd, S. L.; Loebinger, F. K.; Lorah, J. M.; Lorazo, B.; Losty, M. J.; Ludwig, J.; Ma, J.; Macbeth, A. A.; Mannelli, M.; Marcellini, S.; Maringer, G.; Martin, A. J.; Martin, J. P.; Mashimo, T.; Mättig, P.; Maur, U.; McMahon, T. J.; McNutt, J. R.; McPherson, A. C.; Meijers, F.; Menszner, D.; Merritt, F. S.; Mes, H.; Michelini, A.; Middleton, R. P.; Mikenberg, G.; Miller, D. J.; Milstene, C.; Minowa, M.; Mohr, W.; Montanari, A.; Mori, T.; Moss, M. W.; Murphy, P. G.; Murray, W. J.; Nellen, B.; Nguyen, H. H.; Nozaki, M.; O'Dowd, A. J. P.; O'Neale, S. W.; O'Neill, B. P.; Oakham, F. G.; Odorici, F.; Ogg, M.; Oh, H.; Oreglia, M. J.; Orito, S.; Pansart, J. P.; Patrick, G. N.; Pawley, S. J.; Pfister, P.; Pilcher, J. E.; Pinfold, J. L.; Plane, D. E.; Poli, B.; Pouladdej, A.; Pritchard, T. W.; Quast, G.; Raab, J.; Redmond, M. W.; Rees, D. L.; Regimbald, M.; Riles, K.; Roach, C. M.; Robins, S. A.; Rollnik, A.; Roney, J. M.; Rossberg, S.; Rossi, A. M.; Routenburg, P.; Runge, K.; Runolfsson, O.; Sanghera, S.; Sansum, R. A.; Sasaki, M.; Saunders, B. J.; Schaile, A. D.; Schaile, O.; Schappert, W.; Scharff-Hansen, P.; Schreiber, S.; Schwarz, J.; Shapira, A.; Shen, B. C.; Sherwood, P.; Simon, A.; Singh, P.; Siroli, G. P.; Skuia, A.; Smith, A. M.; Smith, T. J.; Snow, G. A.; Springer, R. W.; Sproston, M.; Stephens, K.; Stier, H. E.; Ströhmer, R.; Strom, D.; Takeda, H.; Takeshita, T.; Tsukamoto, T.; Turner, M. F.; Tysarczyk-Niemeyer, G.; Van den plas, D.; VanDalen, G. J.; Vasseur, G.; Virtue, C. J.; von der Schmitt, H.; von Krogh, J.; Wagner, A.; Wahl, C.; Ward, C. P.; Ward, D. R.; Waterhouse, J.; Watkins, P. M.; Watson, A. T.; Watson, N. K.; Weber, M.; Weisz, S.; Wells, P. S.; Wermes, N.; Weymann, M.; Wilson, G. W.; Wilson, J. A.; Wingerter, I.; Winterer, V.-H.; Wood, N. C.; Wotton, S.; Wuensch, B.; Wyatt, T. R.; Yaari, R.; Yang, Y.; Yekutieli, G.; Yoshida, T.; Zeuner, W.; Zorn, G. T.; OPAL Collaboration

1990-09-01

We study the inclusive momentum distribution of charged particles in multihadronic events produced in e +e - annihilations at ECM∼ M(Z 0). We find agreement with the analytical formulae for gluon production that include the phenomena of soft gluon interference. Using data from CM energies between 14 and 91 GeV, we study the dependence of the inclusive momentum distribution on the centre of momentum energy. We find that the analytical formulae describe the data over the entire energy range. Both the momentum distribution at a fixed energy and the change with energy are described by QCD shower Monte Carlo's which include either coherent gluon branchings or string fragmentation. Simple incoherent models with independent fragmentation fail to reproduce the energy dependence and momentum spectra.

Mössbauer spectroscopy of human liver ferritin and its analogue, Ferrum Lek, in the temperature range of 295-90 K: Comparison within the homogeneous iron core model

NASA Astrophysics Data System (ADS)

Alenkina, Irina V.; Oshtrakh, Michael I.; Klencsár, Zoltán; Kuzmann, Ernő; Semionkin, Vladimir A.

2014-10-01

Human liver ferritin and its pharmaceutical analogue, Ferrum Lek, containing nanosized hydrous ferric oxides cores in the forms of ferrihydrite and akaganéite, respectively, were studied using Mössbauer spectroscopy with a high velocity resolution in the temperature range of 295-90 K. To simplify comparison, these spectra were fitted using one quadrupole doublet within the homogeneous iron core model. An unusual line broadening with a temperature decrease was observed in this way for human liver ferritin below ˜150 K and for Ferrum Lek below ˜130 K. Some anomalies were also observed below these temperatures for spectral area and quadrupole splitting. The Debye temperature for both iron cores was evaluated from temperature dependence of isomer shift using the temperature dependence of the second-order Doppler shift.

Broadband, high-resolution investigation of advanced absorption line shapes at high temperature

NASA Astrophysics Data System (ADS)

Schroeder, Paul J.; Cich, Matthew J.; Yang, Jinyu; Swann, William C.; Coddington, Ian; Newbury, Nathan R.; Drouin, Brian J.; Rieker, Gregory B.

2017-08-01

Spectroscopic studies of planetary atmospheres and high-temperature processes (e.g., combustion) require absorption line-shape models that are accurate over extended temperature ranges. To date, advanced line shapes, like the speed-dependent Voigt and Rautian profiles, have not been tested above room temperature with broadband spectrometers. We investigate pure water vapor spectra from 296 to 1305 K acquired with a dual-frequency comb spectrometer spanning from 6800 to 7200 c m-1 at a point spacing of 0.0033 c m-1 and absolute frequency accuracy of <3.3 ×10-6c m-1 . Using a multispectral fitting analysis, we show that only the speed-dependent Voigt accurately models this temperature range with a single power-law temperature-scaling exponent for the broadening coefficients. Only the data from the analysis using this profile fall within theoretical predictions, suggesting that this mechanism captures the dominant narrowing physics for these high-temperature conditions.

Theoretical investigation of the electron capture and loss processes in the collisions of He2+ + Ne.

PubMed

Hong, Xuhai; Wang, Feng; Jiao, Yalong; Su, Wenyong; Wang, Jianguo; Gou, Bingcong

2013-08-28

Based on the time-dependent density functional theory, a method is developed to study ion-atom collision dynamics, which self-consistently couples the quantum mechanical description of electron dynamics with the classical treatment of the ion motion. Employing real-time and real-space method, the coordinate space translation technique is introduced to allow one to focus on the region of target or projectile depending on the actual concerned process. The benchmark calculations are performed for the collisions of He(2+) + Ne, and the time evolution of electron density distribution is monitored, which provides interesting details of the interaction dynamics between the electrons and ion cores. The cross sections of single and many electron capture and loss have been calculated in the energy range of 1-1000 keV/amu, and the results show a good agreement with the available experiments over a wide range of impact energies.

Pesticide risk assessment in free-ranging bees is weather and landscape dependent.

PubMed

Henry, Mickaël; Bertrand, Colette; Le Féon, Violette; Requier, Fabrice; Odoux, Jean-François; Aupinel, Pierrick; Bretagnolle, Vincent; Decourtye, Axel

2014-07-10

The risk assessment of plant protection products on pollinators is currently based on the evaluation of lethal doses through repeatable lethal toxicity laboratory trials. Recent advances in honeybee toxicology have, however, raised interest on assessing sublethal effects in free-ranging individuals. Here, we show that the sublethal effects of a neonicotinoid pesticide are modified in magnitude by environmental interactions specific to the landscape and time of exposure events. Field sublethal assessment is therefore context dependent and should be addressed in a temporally and spatially explicit way, especially regarding weather and landscape physiognomy. We further develop an analytical Effective Dose (ED) framework to help disentangle context-induced from treatment-induced effects and thus to alleviate uncertainty in field studies. Although the ED framework involves trials at concentrations above the expected field exposure levels, it allows to explicitly delineating the climatic and landscape contexts that should be targeted for in-depth higher tier risk assessment.

Memory is relevant in the symmetric phase of the minority game

NASA Astrophysics Data System (ADS)

Ho, K. H.; Man, W. C.; Chow, F. K.; Chau, H. F.

2005-06-01

Minority game is a simple-mined econophysical model capturing the cooperative behavior among selfish players. Previous investigations, which were based on numerical simulations up to about 100 players for a certain parameter α in the range 0.1≲α≲1 , suggested that memory is irrelevant to the cooperative behavior of the minority game in the so-called symmetric phase. Here using a large scale numerical simulation up to about 3000 players in the parameter range 0.01≲α≲1 , we show that the mean variance of the attendance in the minority game actually depends on the memory in the symmetric phase. We explain such dependence in the framework of crowd-anticrowd theory. Our findings conclude that one should not overlook the feedback mechanism buried under the correlation in the history time series in the study of minority game.

Age and sex differences in ranges of motion and motion patterns.

PubMed

Hwang, Jaejin; Jung, Myung-Chul

2015-01-01

This study investigated the effects of age and sex on joint ranges of motion (ROMs) and motion patterns. Forty participants performed 18 motions using eight body segments at self-selected speeds. Older subjects showed smaller ROMs than younger subjects for 11 motions; the greatest difference in ROM was 44.9% for eversion/inversion of the foot. Older subjects also required more time than younger subjects to approach the peak angular velocity for six motions. In contrast, sex significantly affected ROMs but not motion patterns. Male subjects exhibited smaller ROMs than female subjects for four motions; the greatest sex-dependent difference in ROM was 29.7% for ulnar/radial deviation of the hand. The age and sex effects depended on the specific segments used and motions performed, possibly because of differences in anatomical structures and frequencies of use of the joints in habitual physical activities between the groups.

Strong-field ionization of H{sub 2} from ultraviolet to near-infrared wavelengths: Photoelectron energy and angular identifications

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

Wilbois, Timo; Helm, Hanspeter

2011-11-15

Strong-field ionization of molecular hydrogen is studied at wavelengths ranging from 300 to 800 nm using pulses of 100-fs duration. We find that over this wide wavelength range, from nominally 4-photon to 11-photon ionization, resonance features dominate the ionization probability at intensities below 10{sup 14} W/cm{sup 2}. Photoelectron momentum maps recorded by an imaging spectrometer are analyzed to identify the wavelength-dependent ionization pathways in single ionization of molecular hydrogen. A number of models, some empirical, which are appropriate for a quantitative interpretation of the spectra and the ionization yield are introduced. A near-absolute comparison of measured ionization yields at 398more » nm is made with the predictions based on a numerical solution [Y. V. Vanne and A. Saenz, Phys. Rev. A 79, 023421 (2009)] of the time-dependent Schroedinger equation for two correlated electrons.« less

Break of slope in earthquake size distribution and creep rate along the San Andreas Fault system

NASA Astrophysics Data System (ADS)

Shebalin, P.; Narteau, C.; Vorobieva, I.

2017-12-01

Crustal faults accommodate slip either by a succession of earthquakes or continuous slip, andin most instances, both these seismic and aseismic processes coexist. Recorded seismicity and geodeticmeasurements are therefore two complementary data sets that together document ongoing deformationalong active tectonic structures. Here we study the influence of stable sliding on earthquake statistics.We show that creep along the San Andreas Fault is responsible for a break of slope in the earthquake sizedistribution. This slope increases with an increasing creep rate for larger magnitude ranges, whereas itshows no systematic dependence on creep rate for smaller magnitude ranges. This is interpreted as a deficitof large events under conditions of faster creep where seismic ruptures are less likely to propagate. Theseresults suggest that the earthquake size distribution does not only depend on the level of stress but also onthe type of deformation.

Binding energies and modelling of nuclei in semiclassical simulations

NASA Astrophysics Data System (ADS)

Pérez-García, M. Ángeles; Tsushima, K.; Valcarce, A.

2008-03-01

We study the binding energies of spin isospin saturated nuclei with nucleon number 8⩽A⩽100 in semiclassical Monte Carlo many-body simulations. The model Hamiltonian consists of (i) nucleon kinetic energy, (ii) a nucleon nucleon interaction potential, and (iii) an effective Pauli potential which depends on density. The basic ingredients of the nucleon nucleon potential are a short-range repulsion, and a medium-range attraction. Our results demonstrate that one can always expect to obtain the empirical binding energies for a set of nuclei by introducing a proper density dependent Pauli potential in terms of a single variable, the nucleon number, A. The present work shows that in the suggested procedure there is a delicate counterbalance of kinetic and potential energetic contributions allowing a good reproduction of the experimental nuclear binding energies. This type of calculations may be of interest in further reproduction of other properties of nuclei such as radii and also exotic nuclei.

Evaluation of polymerization-dependent changes in color and translucency of resin composites using two formulae.

PubMed

Paravina, Rade D; Kimura, Mikio; Powers, John M

2005-09-01

The aim of this study was to evaluate polymerization-dependent changes in the color and translucency parameter (TP) of resin composites and to compare results obtained using two color-difference metric formulae, CIELAB and CIEDE 2000. Twenty-eight shades of commercial resin composites were analyzed. Specimens (n = 5) were made as discs, 11 mm in diameter and 2-mm thick, using cylindrical molds. Data were collected before and after composite polymerization, using a spectrophotometer. In regard to in vitro color changes of composites (DeltaE*) a DeltaE76 of 3.7 or greater was considered to be an unacceptable color change. Data were analyzed by analysis of variance, and Fisher's protected least significant difference (PLSD) intervals for comparison of means were calculated at the 0.05 level of significance. Mean polymerization-dependent differences in color were DeltaE00 = 4.48 (2.11) and DeltaE76 = 5.51 (2.68). The DeltaTP00 range was 2.57, while the DeltaTP76 range was 2.89. Mean polymerization-dependent differences in translucency were DeltaTP00 = 0.84 (0.77) and DeltaTP76 = 0.87 (0.76). Analysis of variance showed significant differences among composites, shades, and their interactions (P < 0.0001; power = 1.0). Regression equations and r values for the two color-difference formulae and all evaluated TP values showed very strong correlation. In conclusion, within the limitations of this study, polymerization-dependent changes in color and translucency were highly varied. The majority of shades showed polymerization-dependent differences in color higher than the DeltaE76 = 3.7. The TP generally increased after light polymerization by light activation. The very strong correlation (r > 0.97) between the two color-difference formulae indicates that the limitations of the CIELAB system do not appear to be a problem when evaluating composites; however, recorded differences between DeltaE76 and DeltaE00 values stress the importance of data conversion.

Changes in Rod and Frame Test Scores Recorded in Schoolchildren during Development – A Longitudinal Study

PubMed Central

Bagust, Jeff; Docherty, Sharon; Haynes, Wayne; Telford, Richard; Isableu, Brice

2013-01-01

The Rod and Frame Test has been used to assess the degree to which subjects rely on the visual frame of reference to perceive vertical (visual field dependence- independence perceptual style). Early investigations found children exhibited a wide range of alignment errors, which reduced as they matured. These studies used a mechanical Rod and Frame system, and presented only mean values of grouped data. The current study also considered changes in individual performance. Changes in rod alignment accuracy in 419 school children were measured using a computer-based Rod and Frame test. Each child was tested at school Grade 2 and retested in Grades 4 and 6. The results confirmed that children displayed a wide range of alignment errors, which decreased with age but did not reach the expected adult values. Although most children showed a decrease in frame dependency over the 4 years of the study, almost 20% had increased alignment errors suggesting that they were becoming more frame-dependent. Plots of individual variation (SD) against mean error allowed the sample to be divided into 4 groups; the majority with small errors and SDs; a group with small SDs, but alignments clustering around the frame angle of 18°; a group showing large errors in the opposite direction to the frame tilt; and a small number with large SDs whose alignment appeared to be random. The errors in the last 3 groups could largely be explained by alignment of the rod to different aspects of the frame. At corresponding ages females exhibited larger alignment errors than males although this did not reach statistical significance. This study confirms that children rely more heavily on the visual frame of reference for processing spatial orientation cues. Most become less frame-dependent as they mature, but there are considerable individual differences. PMID:23724139

Non-local propagation of correlations in long-range interacting quantum systems

NASA Astrophysics Data System (ADS)

Lee, A. C.; Richerme, P.; Gong, Z.-X.; Senko, C.; Smith, J.; Foss-Feig, M.; Michalakis, S.; Gorshkov, A. V.; Monroe, C.

2014-05-01

The maximum speed with which information can propagate in a many body quantum system can dictate how demanding the system is to describe numerically and also how quickly disparate sites can become correlated. While these kinds of phenomena may be difficult or even impossible for classical computers to describe, trapped ions provide an excellent platform for investigating this rich quantum many-body physics. Using single-site resolved state-dependent imaging, we experimentally determine the spatial and time-dependent correlations of a far-from-equilibrium quantum many-body system evolving under a long-range Ising- or XY-model Hamiltonian. For varying interaction ranges, we extract the shape of the ``light'' cone and measure the velocity with which correlations propagate through the system. In many cases, we find increasing propagation velocities, which violate the prediction for short-range interactions and, in one instance, cannot be explained by any existing theory. Our results show that even for modest system sizes, trapped ion quantum simulators are well poised to study complex many-body physics which are intractable to classical methods. This work is supported by grants from the U.S. Army Research Office with funding from the DARPA OLE program, IARPA, and the MURI program; and the NSF Physics Frontier Center at JQI.

The value of forage measurement information in rangeland management. [implementation of satellite data in range management

NASA Technical Reports Server (NTRS)

Lietzke, K. R.

1975-01-01

An economic model and simulation are developed to estimate the potential social benefit arising from the use of alternative measurement systems in rangeland management. In order to estimate these benefits, it was necessary to model three separate systems: the range environment, the rangeland manager, and the information system which links the two. The rancher's decision-making behavior is modeled according to sound economic principles. Results indicate substantial potential benefits, particularly when used in assisting management of government-operated ranges; possible annual benefits in this area range from $20 to $46 million, depending upon the system capabilities assumed. Possible annual benefit in privately-managed stocker operations range from $2.8 to $49.5 million, depending upon where actual rancher capabilities lie and what system capabilities are assumed.

Preliminary evidence that exercise dependence is associated with blunted cardiac and cortisol reactions to acute psychological stress.

PubMed

Heaney, Jennifer L J; Ginty, Annie T; Carroll, Douglas; Phillips, Anna C

2011-02-01

Low or blunted cardiovascular and cortisol reactions to acute psychological stress have been shown to characterise those with a tobacco or alcohol dependency. The present study tested the hypothesis that exercise dependency would be similarly associated with blunted reactivity. Young female exercisers (N=219) were screened by questionnaire for exercise dependence. Ten women with probable exercise dependence and 10 non dependent controls were selected for laboratory stress testing. Cardiovascular activity and salivary cortisol were measured at rest and in response to a 10-min mental arithmetic stress task. The exercise dependent women showed blunted cardiac reactions to the stress task and blunted cortisol at 10, 20, and 30 minute post stress exposure. These effects could not be accounted for in terms of group differences in stress task performance, nor could the cardiac effects be attributed to group differences in cardio-respiratory fitness. It would seem that low stress reactivity is characteristic of a wide range of dependencies, and is not confined to substance dependence. Our results offer further support for the hypothesis that blunted stress reactivity may be a peripheral marker of a central motivational dysregulation. Copyright © 2010 Elsevier B.V. All rights reserved.

Modelling and measurement of bandgap behaviour in medium-wavelength IR InAs/InAs0.815Sb0.185 strained-layer superlattices

NASA Astrophysics Data System (ADS)

Letka, Veronica; Keen, James; Craig, Adam; Marshall, Andrew R. J.

2017-10-01

InAs/InAs1-xSbx type-II strained-layer superlattices (SLS) are a structure with potential infrared detection applications, owing to its tunable bandgap and suppressed Auger recombination. A series of medium-wavelength infrared (MWIR) InAs/InAs0.815Sb0.185 SLS structures, grown as undoped absorption epilayers on GaAs, were fabricated using molecular beam epitaxy in order to study the dependence of the ground state transitions on temperature and superlattice period thickness. Photoluminescence peaks at 4 K were obtained with the use of a helium-cooled micro-PL system and an InSb detector, and temperature-dependent absorption spectra were measured in the range 77 K - 300 K on a Fourier Transform Infrared (FTIR) spectrometer, equipped with a 1370 K blackbody source and a DTGS detector. An nBn device sample with the absorber structure identical to one of the undoped samples was also grown and processed with the goal of measuring temperature-dependent spectral response. A model for superlattice band alignment was also devised, incorporating the Bir-Pikus transformation results for uniaxial and biaxial strain, and the Einstein oscillator model for bandgap temperature dependence. Absorption coefficients of several 1000 cm-1 throughout the entire MWIR range are found for all samples, and temperature dependence of the bandgaps is extracted and compared to the model. This and photoluminescence data also demonstrate bandgap shifts consistent with the different superlattice periods of the three samples.

Nano porous silicon microcavity sensor for determination organic solvents and pesticide in water

NASA Astrophysics Data System (ADS)

Pham, Van Hoi; Van Nguyen, Thuy; Nguyen, The Anh; Pham, Van Dai; Bui, Huy

2014-12-01

In this paper we present a sensing method using nano-porous silicon microcavity sensor, which was developed in order to obtain simultaneous determination of two volatile substances with different solvent concentrations as well as very low pesticide concentration in water. The temperature of the solution and the velocity of the air stream flowing through the solution have been used to control the response of the sensor for different solvent solutions. We study the dependence of the cavity-resonant wavelength shift on solvent concentration, velocity of the airflow and solution temperature. The wavelength shift depends linearly on concentration and increases with solution temperature and velocity of the airflow. The dependence of the wavelength shift on the solution temperature in the measurement contains properties of the temperature dependence of the solvent vapor pressure, which characterizes each solvent. As a result, the dependence of the wavelength shift on the solution temperature discriminates between solutions of ethanol and acetone with different concentrations. This suggests a possibility for the simultaneous determination of the volatile substances and their concentrations. On the other hand, this method is able to detect the presence of atrazine pesticide by the shift of the resonant wavelength, with good sensitivity (0.3 nm pg-1 ml) and limit of detection (LOD) (0.8-1.4 pg ml-1), that we tested for concentrations in the range from 2.15 to 21.5 pg ml-1, which is the range useful for monitoring acceptable water for human consumption.

Variations of thiaminase I activity pH dependencies among typical Great Lakes forage fish and Paenibacillus thiaminolyticus.

USGS Publications Warehouse

Zajicek, J.L.; Brown, L.; Brown, S.B.; Honeyfield, D.C.; Fitzsimons, J.D.; Tillitt, D.E.

2009-01-01

The source of thiaminase in the Great Lakes food web remains unknown. Biochemical characterization of the thiaminase I activities observed in forage fish was undertaken to provide insights into potential thiaminase sources and to optimize catalytic assay conditions. We measured the thiaminase I activities of crude extracts from five forage fish species and one strain of Paenibacillus thiaminolyticus over a range of pH values. The clupeids, alewife Alosa pseudoharengus and gizzard shad Dorosoma cepedianum, had very similar thiaminase I pH dependencies, with optimal activity ranges (> or = 90% of maximum activity) between pH 4.6 and 5.5. Rainbow smelt Osmerus mordax and spottail shiner Notropis hudsonius had optimal activity ranges between pH 5.5-6.6. The thiaminase I activity pH dependence profile of P. thiaminolyticus had an optimal activity range between pH 5.4 and 6.3, which was similar to the optimal range for rainbow smelt and spottail shiners. Incubation of P. thiaminolyticus extracts with extracts from bloater Coregonus hoyi (normally, bloaters have little or no detectable thiaminase I activity) did not significantly alter the pH dependence profile of P. thiaminolyticus-derived thiaminase I, such that it continued to resemble that of the rainbow smelt and spottail shiner, with an apparent optimal activity range between pH 5.7 and 6.6. These data are consistent with the hypothesis of a bacterial source for thiaminase I in the nonclupeid species of forage fish; however, the data also suggest different sources of thiaminase I enzymes in the clupeid species.

Technical Note: Statistical dependences between channels in radiochromic film readings. Implications in multichannel dosimetry.

PubMed

González-López, Antonio; Vera-Sánchez, Juan Antonio; Ruiz-Morales, Carmen

2016-05-01

This note studies the statistical relationships between color channels in radiochromic film readings with flatbed scanners. The same relationships are studied for noise. Finally, their implications for multichannel film dosimetry are discussed. Radiochromic films exposed to wedged fields of 6 MV energy were read in a flatbed scanner. The joint histograms of pairs of color channels were used to obtain the joint and conditional probability density functions between channels. Then, the conditional expectations and variances of one channel given another channel were obtained. Noise was extracted from film readings by means of a multiresolution analysis. Two different dose ranges were analyzed, the first one ranging from 112 to 473 cGy and the second one from 52 to 1290 cGy. For the smallest dose range, the conditional expectations of one channel given another channel can be approximated by linear functions, while the conditional variances are fairly constant. The slopes of the linear relationships between channels can be used to simplify the expression that estimates the dose by means of the multichannel method. The slopes of the linear relationships between each channel and the red one can also be interpreted as weights in the final contribution to dose estimation. However, for the largest dose range, the conditional expectations of one channel given another channel are no longer linear functions. Finally, noises in different channels were found to correlate weakly. Signals present in different channels of radiochromic film readings show a strong statistical dependence. By contrast, noise correlates weakly between channels. For the smallest dose range analyzed, the linear behavior between the conditional expectation of one channel given another channel can be used to simplify calculations in multichannel film dosimetry.

Telemetric signal-driven servocontrol of renal perfusion pressure in acute and chronic rat experiments

PubMed Central

Xia, Min; Li, Pin-Lan; Li, Ningjun

2008-01-01

The present study was designed to take advantage of telemetry data acquisition and develop an easy and reliable system to servocontrol renal perfusion pressure (RPP). Digitized pressure signals from lower abdominal aorta in rats, reflecting RPP, was obtained by a telemetry device and dynamically exported into an Excel worksheet. A computer program (LabVIEW) compared the RPP data with a preselected pressure range and drove a bidirectional syringe pump to control the inflation of a vascular occluder around the aorta above renal arteries. When RPP was higher than the preselected range, the syringe pump inflated the occluder and decreased RPP, and vice versa. If RPP was within range, there was no action. In this way, RPP was servocontrolled within the desired range. In experiments with norepinephrine- or ANG II-induced acute increases in systemic arterial pressure (120–145 mmHg), the system controlled RPP at a constant range of 100–105 mmHg within 30–50 s and differentiated the pressure-dependent and -independent effects on renal functions. In Dahl S rats with high-salt-induced hypertension, this system maintained RPP at 100–120 mmHg over 10 days, while systemic arterial pressures were 150 ± 5.9 mmHg in uncontrolled animals. This system also has the ability of simultaneity and multiplexing to control multiple animals. Our results suggest that this is an effective and reliable system to servocontrol RPP, which can be easily established with general computer knowledge. This system provides a powerful tool and may greatly facilitate the studies in pressure-dependent/-independent effects of a variety of cardiovascular factors. PMID:18815205

Technical Note: Statistical dependences between channels in radiochromic film readings. Implications in multichannel dosimetry

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

González-López, Antonio, E-mail: antonio.gonzalez7@carm.es; Vera-Sánchez, Juan Antonio; Ruiz-Morales, Carmen

Purpose: This note studies the statistical relationships between color channels in radiochromic film readings with flatbed scanners. The same relationships are studied for noise. Finally, their implications for multichannel film dosimetry are discussed. Methods: Radiochromic films exposed to wedged fields of 6 MV energy were read in a flatbed scanner. The joint histograms of pairs of color channels were used to obtain the joint and conditional probability density functions between channels. Then, the conditional expectations and variances of one channel given another channel were obtained. Noise was extracted from film readings by means of a multiresolution analysis. Two different dosemore » ranges were analyzed, the first one ranging from 112 to 473 cGy and the second one from 52 to 1290 cGy. Results: For the smallest dose range, the conditional expectations of one channel given another channel can be approximated by linear functions, while the conditional variances are fairly constant. The slopes of the linear relationships between channels can be used to simplify the expression that estimates the dose by means of the multichannel method. The slopes of the linear relationships between each channel and the red one can also be interpreted as weights in the final contribution to dose estimation. However, for the largest dose range, the conditional expectations of one channel given another channel are no longer linear functions. Finally, noises in different channels were found to correlate weakly. Conclusions: Signals present in different channels of radiochromic film readings show a strong statistical dependence. By contrast, noise correlates weakly between channels. For the smallest dose range analyzed, the linear behavior between the conditional expectation of one channel given another channel can be used to simplify calculations in multichannel film dosimetry.« less

Measuring economic outcomes of alcohol treatment using the Economic Form 90.

PubMed

Bray, Jeremy W; Zarkin, Gary A; Miller, William R; Mitra, Debanjali; Kivlahan, Daniel R; Martin, Daniel J; Couper, David J; Cisler, Ron A

2007-03-01

This article assesses the ability of the economic outcome measures in the Economic Form 90 to detect differences across levels of alcohol dependence as measured by the Alcohol Dependence Scale. We used baseline data from the Combining Medications and Behavioral Interventions (COMBINE) Study, a large, multisite clinical trial, to assess the extent to which the economic items on the Economic Form 90 instrument can detect differences across levels of alcohol dependence. After adjusting for differences in demographic characteristics, the Economic Form 90 can detect significant differences across a range of dependence severity levels for the economic outcomes of inpatient medical care, emergency-department medical care, behavioral health care, being on parole or probation, and missed workdays, conditional on being employed. We did not detect significant differences across dependence severity for employment status, outpatient medical care, other criminal justice involvement, or motor vehicle accidents. The Economic Form 90 can identify differences in many economic outcomes associated with differing levels of alcohol dependence. This suggests that the Economic Form 90 may be useful in assessing changes in economic outcomes that result from changes in alcohol dependence.

Species invasion shifts the importance of predator dependence.

PubMed

Griffen, Blaine D; Delaney, David G

2007-12-01

The strength of interference between foraging individuals can influence per capita consumption rates, with important consequences for predator and prey populations and system stability. Here we demonstrate how the replacement of a previously established invader, the predatory crab Carcinus maenas, by the recently invading predatory crab Hemigrapsus sanguineus shifts predation from a species that experiences strong predator interference (strong predator dependence) to one that experiences weak predator interference (weak predator dependence). We demonstrate using field experiments that differences in the strength of predator dependence persist for these species both when they forage on a single focal prey species only (the mussel Mytilus edulis) and when they forage more broadly across the entire prey community. This shift in predator dependence with species replacement may be altering the biomass across trophic levels, consistent with theoretical predictions, as we show that H. sanguineus populations are much larger than C. maenas populations throughout their invaded ranges. Our study highlights that predator dependence may differ among predator species and demonstrates that different predatory impacts of two conspicuous invasive predators may be explained at least in part by different strengths of predator dependence.

Heterogeneity of emotional and interpersonal difficulties in alcohol-dependence: A cluster analytic approach.

PubMed

Maurage, Pierre; Timary, Philippe de; D'Hondt, Fabien

2017-08-01

Emotional and interpersonal impairments have been largely reported in alcohol-dependence, and their role in its development and maintenance is widely established. However, earlier studies have exclusively focused on group comparisons between healthy controls and alcohol-dependent individuals, considering them as a homogeneous population. The variability of socio-emotional profiles in this disorder thus remains totally unexplored. The present study used a cluster analytic approach to explore the heterogeneity of affective and social disorders in alcohol-dependent individuals. 296 recently-detoxified alcohol-dependent patients were first compared with 246 matched healthy controls regarding self-reported emotional (i.e. alexithymia) and social (i.e. interpersonal problems) difficulties. Then, a cluster analysis was performed, focusing on the alcohol-dependent sample, to explore the presence of differential patterns of socio-emotional deficits and their links with demographic, psychopathological and alcohol-related variables. The group comparison between alcohol-dependent individuals and controls clearly confirmed that emotional and interpersonal difficulties constitute a key factor in alcohol-dependence. However, the cluster analysis identified five subgroups of alcohol-dependent individuals, presenting distinct combinations of alexithymia and interpersonal problems ranging from a total absence of reported impairment to generalized socio-emotional difficulties. Alcohol-dependent individuals should no more be considered as constituting a unitary group regarding their affective and interpersonal difficulties, but rather as a population encompassing a wide variety of socio-emotional profiles. Future experimental studies on emotional and social variables should thus go beyond mere group comparisons to explore this heterogeneity, and prevention programs proposing an individualized evaluation and rehabilitation of these deficits should be promoted. Copyright © 2017 Elsevier B.V. All rights reserved.

Gas-liquid nucleation at large metastability: unusual features and a new formalism

NASA Astrophysics Data System (ADS)

Santra, Mantu; Singh, Rakesh S.; Bagchi, Biman

2011-03-01

Nucleation at large metastability is still largely an unsolved problem, even though it is a problem of tremendous current interest, with wide-ranging practical value, from atmospheric research to materials science. It is now well accepted that the classical nucleation theory (CNT) fails to provide a qualitative picture and gives incorrect quantitative values for such quantities as activation-free energy barrier and supersaturation dependence of nucleation rate, especially at large metastability. In this paper, we present an alternative formalism to treat nucleation at large supersaturation by introducing an extended set of order parameters in terms of the kth largest liquid-like clusters, where k = 1 is the largest cluster in the system, k = 2 is the second largest cluster and so on. At low supersaturation, the size of the largest liquid-like cluster acts as a suitable order parameter. At large supersaturation, the free energy barrier for the largest liquid-like cluster disappears. We identify this supersaturation as the one at the onset of kinetic spinodal. The kinetic spinodal is system-size-dependent. Beyond kinetic spinodal many clusters grow simultaneously and competitively and hence the nucleation and growth become collective. In order to describe collective growth, we need to consider the full set of order parameters. We derive an analytic expression for the free energy of formation of the kth largest cluster. The expression predicts that, at large metastability (beyond kinetic spinodal), the barrier of growth for several largest liquid-like clusters disappears, and all these clusters grow simultaneously. The approach to the critical size occurs by barrierless diffusion in the cluster size space. The expression for the rate of barrier crossing predicts weaker supersaturation dependence than what is predicted by CNT at large metastability. Such a crossover behavior has indeed been observed in recent experiments (but eluded an explanation till now). In order to understand the large numerical discrepancy between simulation predictions and experimental results, we carried out a study of the dependence on the range of intermolecular interactions of both the surface tension of an equilibrium planar gas-liquid interface and the free energy barrier of nucleation. Both are found to depend significantly on the range of interaction for the Lennard-Jones potential, both in two and three dimensions. The value of surface tension and also the free energy difference between the gas and the liquid phase increase significantly and converge only when the range of interaction is extended beyond 6-7 molecular diameters. We find, with the full range of interaction potential, that the surface tension shows only a weak dependence on supersaturation, so the reason for the breakdown of CNT (with simulated values of surface tension and free energy gap) cannot be attributed to the supersaturation dependence of surface tension. This remains an unsettled issue at present because of the use of the value of surface tension obtained at coexistence.

Dosimetric characteristics of a PIN diode for radiotherapy application.

PubMed

Kumar, R; Sharma, S D; Philomina, A; Topkar, A

2014-08-01

The PIN diode developed by Bhabha Atomic Research Centre (BARC) was modified for its use as a dosimeter in radiation therapy. For this purpose the diode was mounted on a printed circuit board (PCB) and provided with necessary connections so that its response against irradiation can be recorded by a standard radiotherapy electrometer. The dosimetric characteristics of the diode were studied in Co-60 gamma rays as well as high energy X-rays. The measured sensitivity of this PIN diode is 4 nC/cGy which is about ten times higher than some commercial diode dosimeters. The leakage current from the diode is 0.04 nA. The response of the PIN diode is linear in the range of 20-1000 cGy which covers the full range of radiation dose encountered in radiotherapy treatments. The non-linearity of the diode response is 3.5% at 20 cGy and it is less than 1.5% at higher dose values. Its repeatability is within 0.5%. The angular response variation is about 5.6% within 6608 with respect to normal beam incidence. The response of the PIN diode at 6 and 18 MV X-rays varies within 2% with respect to its response at Co-60 gamma rays. The source to surface distance (SSD) dependence of the PIN diode was studied for Co-60 beam. It was found that the response of the diode decreases almost linearly relative to given dose for beams with constant collimator setting but increasing SSD (decreasing dose-rate). Within this study the diode response varied by about 2.5% between the maximum and minimum SSD. The dose-rate dependence of the PIN diode for 6 and 15 MV-rays was studied. The variation in response of diode for both energies in the studied dose range is less than 1%. The field size dependence of the PIN diode response is within 1% with respect to the response of ionisation chamber. These studies indicate that the characteristics of the PIN diode are suitable for use in radiotherapy dosimetry.

Total target volume is a better predictor of whole brain dose from gamma stereotactic radiosurgery than the number, shape, or location of the lesions

PubMed Central

Narayanasamy, Ganesh; Smith, Adam; Van Meter, Emily; McGarry, Ronald; Molloy, Janelle A.

2013-01-01

Purpose: To assess the hypothesis that the volume of whole brain that receives a certain dose level is primarily dependent on the treated volume rather than on the number, shape, or location of the lesions. This would help a physician validate the suitability of GammaKnife® based stereotactic radiosurgery (GKSR) prior to treatment. Methods: Simulation studies were performed to establish the hypothesis for both oblong and spherical shaped lesions of various numbers and sizes. Forty patients who underwent GKSR [mean age of 54 years (range 7–80), mean number of lesions of 2.5 (range 1–6), and mean lesion volume of 4.4 cm3 (range 0.02–22.2 cm3)] were also studied retrospectively. Following recommendations of QUANTEC, the volume of brain irradiated by the 12 Gy (VB12) isodose line was measured and a power-law based relation is proposed here for estimating VB12 from the known tumor volume and the prescription dose. Results: In the simulation study on oblong, spherical, and multiple lesions, the volume of brain irradiated by 50%, 10%, and 1% of maximum dose was found to have linear, linear, and exponentially increasing dependence on the volume of the treated region, respectively. In the retrospective study on 40 GKSR patients, a similar relationship was found to predict the brain dose with a Spearman correlation coefficient >0.9. In both the studies, the volume of brain irradiated by a certain dose level does not have a statistically significant relationship (p ≥ 0.05) with the number, shape, or position of the lesions. The measured VB12 agrees with calculation to within 1.7%. Conclusions: The results from the simulation and the retrospective clinical studies indicate that the volume of whole brain that receives a certain percentage of the maximum dose is primarily dependent on the treated volume and less on the number, shape, and location of the lesions. PMID:24007147

Strain amplitude-dependent anelasticity in Cu-Ni solid solution due to thermally activated and athermal dislocation-point obstacle interactions

NASA Astrophysics Data System (ADS)

Kustov, S.; Gremaud, G.; Benoit, W.; Golyandin, S.; Sapozhnikov, K.; Nishino, Y.; Asano, S.

1999-02-01

Experimental investigations of the internal friction and the Young's modulus defect in single crystals of Cu-(1.3-7.6) at. % Ni have been performed for 7-300 K over a wide range of oscillatory strain amplitudes. Extensive data have been obtained at a frequency of vibrations around 100 kHz and compared with the results obtained for the same crystals at a frequency of ˜1 kHz. The strain amplitude dependence of the anelastic strain amplitude and the average friction stress acting on a dislocation due to solute atoms are also analyzed. Several stages in the strain amplitude dependence of the internal friction and the Young's modulus defect are revealed for all of the alloy compositions, at different temperatures and in different frequency ranges. For the 100 kHz frequency, low temperatures and low strain amplitudes (˜10-7-10-5), the amplitude-dependent internal friction and the Young's modulus defect are essentially temperature independent, and are ascribed to a purely hysteretic internal friction component. At higher strain amplitudes, a transition stage and a steep strain amplitude dependence of the internal friction and the Young's modulus defect are observed, followed by saturation at the highest strain amplitudes employed. These stages are temperature and frequency dependent and are assumed to be due to thermally activated motion of dislocations. We suggest that the observed regularities in the entire strain amplitude, temperature and frequency ranges correspond to a motion of dislocations in a two-component system of obstacles: weak but long-range ones, due to the elastic interaction of dislocations with solute atoms distributed in the bulk of the crystal; and strong short-range ones, due to the interaction of dislocations with solute atoms distributed close to dislocation glide planes. Based on these assumptions, a qualitative explanation is given for the variety of experimental observations.

Orientation and temperature dependence of some mechanical properties of the single-crystal nickel-base superalloy Rene N4. II - Low cycle fatigue behavior

NASA Technical Reports Server (NTRS)

Gabb, T. P.; Gayda, J.; Miner, R. V.

1986-01-01

The low cycle fatigue (LCF) properties of a single-crystal nickel-base superalloy Rene N4, have been examined at 760 and 980 C in air. Specimens having crystallographic orientations near the 001, 011, -111, 023, -236, and -145 lines were tested in fully reversed, total-strain-controlled LCF tests at a frequency of 0.1 Hz. At 760 C, this alloy exhibited orientation dependent tension-compression anisotropies of yielding which continued to failure. Also at 760 C, orientations exhibiting predominately single slip exhibited serrated yielding for many cycles. At 980 C, orientation dependencies of yielding behavior were smaller. In spite of the tension-compression anisotropies, cyclic stress range-strain range behavior was not strongly orientation dependent for either test temperature. Fatigue life on a total strain range basis was highly orientation dependent at 760 and 980 C and was related chiefly to elastic modulus, low modulus orientations having longer lives. Stage I crack growth on 111 planes was dominant at 760 C, while Stage II crack growth occurred at 980 C. Crack initiation generally occurred at near-surface micropores, but occasionally at oxidation spikes in the 980 C tests.

Improvement of range spatial resolution of medical ultrasound imaging by element-domain signal processing

NASA Astrophysics Data System (ADS)

Hasegawa, Hideyuki

2017-07-01

The range spatial resolution is an important factor determining the image quality in ultrasonic imaging. The range spatial resolution in ultrasonic imaging depends on the ultrasonic pulse length, which is determined by the mechanical response of the piezoelectric element in an ultrasonic probe. To improve the range spatial resolution without replacing the transducer element, in the present study, methods based on maximum likelihood (ML) estimation and multiple signal classification (MUSIC) were proposed. The proposed methods were applied to echo signals received by individual transducer elements in an ultrasonic probe. The basic experimental results showed that the axial half maximum of the echo from a string phantom was improved from 0.21 mm (conventional method) to 0.086 mm (ML) and 0.094 mm (MUSIC).

Capture-Recapture Estimators in Epidemiology with Applications to Pertussis and Pneumococcal Invasive Disease Surveillance

PubMed Central

Braeye, Toon; Verheagen, Jan; Mignon, Annick; Flipse, Wim; Pierard, Denis; Huygen, Kris; Schirvel, Carole; Hens, Niel

2016-01-01

Introduction Surveillance networks are often not exhaustive nor completely complementary. In such situations, capture-recapture methods can be used for incidence estimation. The choice of estimator and their robustness with respect to the homogeneity and independence assumptions are however not well documented. Methods We investigated the performance of five different capture-recapture estimators in a simulation study. Eight different scenarios were used to detect and combine case-information. The scenarios increasingly violated assumptions of independence of samples and homogeneity of detection probabilities. Belgian datasets on invasive pneumococcal disease (IPD) and pertussis provided motivating examples. Results No estimator was unbiased in all scenarios. Performance of the parametric estimators depended on how much of the dependency and heterogeneity were correctly modelled. Model building was limited by parameter estimability, availability of additional information (e.g. covariates) and the possibilities inherent to the method. In the most complex scenario, methods that allowed for detection probabilities conditional on previous detections estimated the total population size within a 20–30% error-range. Parametric estimators remained stable if individual data sources lost up to 50% of their data. The investigated non-parametric methods were more susceptible to data loss and their performance was linked to the dependence between samples; overestimating in scenarios with little dependence, underestimating in others. Issues with parameter estimability made it impossible to model all suggested relations between samples for the IPD and pertussis datasets. For IPD, the estimates for the Belgian incidence for cases aged 50 years and older ranged from 44 to58/100,000 in 2010. The estimates for pertussis (all ages, Belgium, 2014) ranged from 24.2 to30.8/100,000. Conclusion We encourage the use of capture-recapture methods, but epidemiologists should preferably include datasets for which the underlying dependency structure is not too complex, a priori investigate this structure, compensate for it within the model and interpret the results with the remaining unmodelled heterogeneity in mind. PMID:27529167

Characteristics of pitch angle distributions of relativistic electrons under the interaction with Pc5 waves in the inner magnetosphere

NASA Astrophysics Data System (ADS)

Kamiya, K.; Seki, K.; Saito, S.; Amano, T.; Yoshizumi, M.

2017-12-01

Radial transport of relativistic electrons in the inner magnetosphere has been considered as one of acceleration mechanisms of the outer radiation belt electrons and can be driven by the drift resonance with ULF waves in the Pc5 frequency range. The maximum changes of the electron in the radial distance (L) due to the drift resonance depend on the electron energy, pitch angle, and Pc5 wave structure. Those dependences are expected to form the characteristic pitch angle distributions (PADs) as a function of L and electron energy. In this study, we investigate PADs of relativistic electrons due to the drift resonance with a monochromatic Pc5 wave by using two simulation models of the inner magnetosphere: GEMSIS-Ring Current (RC) and GEMSIS-Radiation Belt (RB) models. The GEMSIS-RB simulations calculate guiding center trajectories of relativistic electrons in electric and magnetic fields obtained from the GEMSIS-RC model, which simulates a monochromatic Pc5 wave propagation in the inner magnetosphere. The results show the characteristic PADs depending on the energy and L, which is explicable with the pitch angle dependence of resonance conditions. At a fixed location, those PADs can change from pancake (90°peaked) to butterfly (two peaks in oblique PAs) distributions as the transport by the monochromatic Pc5 wave progresses. These butterfly distributions are seen in the L range where electrons with lower PAs satisfy the resonance condition. It is also found that the lower PA electron with a fixed magnetic moment can be transported deeper inside because of the PA changes to larger values through the adiabatic transport, which enables them to satisfy the efficient resonance condition in wider L range compared to the 90 degrees PA electrons.

The in vitro respiratory toxicity of cristobalite-bearing volcanic ash.

PubMed

Damby, David E; Murphy, Fiona A; Horwell, Claire J; Raftis, Jennifer; Donaldson, Kenneth

2016-02-01

Ash from dome-forming volcanoes poses a unique hazard to millions of people worldwide due to an abundance of respirable cristobalite, a crystalline silica polymorph. Crystalline silica is an established respiratory hazard in other mixed dusts, but its toxicity strongly depends on sample provenance. Previous studies suggest that cristobalite-bearing volcanic ash is not as bio-reactive as may be expected for a dust containing crystalline silica. We systematically address the hazard posed by volcanic cristobalite by analysing a range of dome-related ash samples, and interpret the crystalline silica hazard according to the mineralogical nature of volcanic cristobalite. Samples are sourced from five well-characterized dome-forming volcanoes that span a range of magmatic compositions, specifically selecting samples rich in cristobalite (up to 16wt%). Isolated respirable fractions are used to investigate the in vitro response of THP-1 macrophages and A549 type II epithelial cells in cytotoxicity, cellular stress, and pro-inflammatory assays associated with crystalline silica toxicity. Dome-related ash is minimally reactive in vitro for a range of source compositions and cristobalite contents. Cristobalite-based toxicity is not evident in the assays employed, supporting the notion that crystalline silica provenance influences reactivity. Macrophages experienced minimal ash-induced cytotoxicity and intracellular reduction of glutathione; however, production of IL-1β, IL-6 and IL-8 were sample-dependent. Lung epithelial cells experienced moderate apoptosis, sample-dependent reduction of glutathione, and minimal cytokine production. We suggest that protracted interaction between particles and epithelial cells may never arise due to effective clearance by macrophages. However, volcanic ash has the propensity to incite a low, but significant, and sample-dependent response; the effect of this response in vivo is unknown and prolonged exposure may yet pose a hazard. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Radiation defect dynamics in Si at room temperature studied by pulsed ion beams

NASA Astrophysics Data System (ADS)

Wallace, J. B.; Charnvanichborikarn, S.; Bayu Aji, L. B.; Myers, M. T.; Shao, L.; Kucheyev, S. O.

2015-10-01

The evolution of radiation defects after the thermalization of collision cascades often plays the dominant role in the formation of stable radiation disorder in crystalline solids of interest to electronics and nuclear materials applications. Here, we explore a pulsed-ion-beam method to study defect interaction dynamics in Si crystals bombarded at room temperature with 500 keV Ne, Ar, Kr, and Xe ions. The effective time constant of defect interaction is measured directly by studying the dependence of lattice disorder, monitored by ion channeling, on the passive part of the beam duty cycle. The effective defect diffusion length is revealed by the dependence of damage on the active part of the beam duty cycle. Results show that the defect relaxation behavior obeys a second order kinetic process for all the cases studied, with a time constant in the range of ˜4-13 ms and a diffusion length of ˜15-50 nm. Both radiation dynamics parameters (the time constant and diffusion length) are essentially independent of the maximum instantaneous dose rate, total ion dose, and dopant concentration within the ranges studied. However, both the time constant and diffusion length increase with increasing ion mass. This demonstrates that the density of collision cascades influences not only defect production and annealing efficiencies but also the defect interaction dynamics.

Improvement of attention with amphetamine in low- and high-performing rats.

PubMed

Turner, Karly M; Burne, Thomas H J

2016-09-01

Attentional deficits occur in a range of neuropsychiatric disorders, such as schizophrenia and attention deficit hyperactivity disorder. Psychostimulants are one of the main treatments for attentional deficits, yet there are limited reports of procognitive effects of amphetamine in preclinical studies. Therefore, task development may be needed to improve predictive validity when measuring attention in rodents. This study aimed to use a modified signal detection task (SDT) to determine if and at what doses amphetamine could improve attention in rats. Sprague-Dawley rats were trained on the SDT prior to amphetamine challenge (0.1, 0.25, 0.75 and 1.25 mg/kg). This dose range was predicted to enhance and disrupt cognition with the effect differing between individuals depending on baseline performance. Acute low dose amphetamine (0.1 and 0.25 mg/kg) improved accuracy, while the highest dose (1.25 mg/kg) significantly disrupted performance. The effects differed for low- and high-performing groups across these doses. The effect of amphetamine on accuracy was found to significantly correlate with baseline performance in rats. This study demonstrates that improvement in attentional performance with systemic amphetamine is dependent on baseline accuracy in rats. Indicative of the inverted U-shaped relationship between dopamine and cognition, there was a baseline-dependent shift in performance with increasing doses of amphetamine. The SDT may be a useful tool for investigating individual differences in attention and response to psychostimulants in rodents.

Temperature dependence of the plastic scintillator detector for DAMPE

NASA Astrophysics Data System (ADS)

Wang, Zhao-Min; Yu, Yu-Hong; Sun, Zhi-Yu; Yue, Ke; Yan, Duo; Zhang, Yong-Jie; Zhou, Yong; Fang, Fang; Huang, Wen-Xue; Chen, Jun-Ling

2017-01-01

The Plastic Scintillator Detector (PSD) is one of the main sub-detectors in the DArk Matter Particle Explorer (DAMPE) project. It will be operated over a large temperature range from -10 to 30 °C, so the temperature effect of the whole detection system should be studied in detail. The temperature dependence of the PSD system is mainly contributed by the three parts: the plastic scintillator bar, the photomultiplier tube (PMT), and the Front End Electronics (FEE). These three parts have been studied in detail and the contribution of each part has been obtained and discussed. The temperature coefficient of the PMT is -0.320(±0.033)%/°C, and the coefficient of the plastic scintillator bar is -0.036(±0.038)%/°C. This result means that after subtracting the FEE pedestal, the variation of the signal amplitude of the PMT-scintillator system due to temperature mainly comes from the PMT, and the plastic scintillator bar is not sensitive to temperature over the operating range. Since the temperature effect cannot be ignored, the temperature dependence of the whole PSD has been also studied and a correction has been made to minimize this effect. The correction result shows that the effect of temperature on the signal amplitude of the PSD system can be suppressed. Supported by Strategic Priority Research Program on Space Science of the Chinese Academy of Sciences (XDA04040202-3) and Youth Innovation Promotion Association, CAS

Galaxy And Mass Assembly (GAMA): the mass-metallicity relationship

NASA Astrophysics Data System (ADS)

Foster, C.; Hopkins, A. M.; Gunawardhana, M.; Lara-López, M. A.; Sharp, R. G.; Steele, O.; Taylor, E. N.; Driver, S. P.; Baldry, I. K.; Bamford, S. P.; Liske, J.; Loveday, J.; Norberg, P.; Peacock, J. A.; Alpaslan, M.; Bauer, A. E.; Bland-Hawthorn, J.; Brough, S.; Cameron, E.; Colless, M.; Conselice, C. J.; Croom, S. M.; Frenk, C. S.; Hill, D. T.; Jones, D. H.; Kelvin, L. S.; Kuijken, K.; Nichol, R. C.; Owers, M. S.; Parkinson, H. R.; Pimbblet, K. A.; Popescu, C. C.; Prescott, M.; Robotham, A. S. G.; Lopez-Sanchez, A. R.; Sutherland, W. J.; Thomas, D.; Tuffs, R. J.; van Kampen, E.; Wijesinghe, D.

2012-11-01

Context. The mass-metallicity relationship (MMR) of star-forming galaxies is well-established, however there is still some disagreement with respect to its exact shape and its possible dependence on other observables. Aims: We measure the MMR in the Galaxy And Mass Assembly (GAMA) survey. We compare our measured MMR to that measured in the Sloan Digital Sky Survey (SDSS) and study the dependence of the MMR on various selection criteria to identify potential causes for disparities seen in the literature. Methods: We use strong emission line ratio diagnostics to derive oxygen abundances. We then apply a range of selection criteria for the minimum signal-to-noise in various emission lines, as well as the apparent and absolute magnitude to study variations in the inferred MMR. Results: The shape and position of the MMR can differ significantly depending on the metallicity calibration and selection used. After selecting a robust metallicity calibration amongst those tested, we find that the mass-metallicity relation for redshifts 0.061 ≲ z ≲ 0.35 in GAMA is in reasonable agreement with that found in the SDSS despite the difference in the luminosity range probed. Conclusions: In view of the significant variations of the MMR brought about by reasonable changes in the sample selection criteria and method, we recommend that care be taken when comparing the MMR from different surveys and studies directly. We also conclude that there could be a modest level of evolution over 0.06 ≤ z ≤ 0.35 within the GAMA sample.

Characterization of the relationship of the cure cycle chemistry to cure cycle processing properties

NASA Technical Reports Server (NTRS)

Kranbuehl, D. E.

1985-01-01

Dynamic dielectric analysis (DDA) is used to study curing polymer systems and thermoplastics. Measurements are made over a frequency range of six decades. This wide range of frequencies increases the amount of information which can be obtained. The data is analyzed in terms of the frequency dependence of the complex permittivity epsilon sup *, specific conductivity sigma (ohm/cm) and the relaxation time tau, parameters which are characteristic of the cure state of the material and independent of the size of the sample.

Bottomonium above deconfinement in lattice nonrelativistic QCD.

PubMed

Aarts, G; Kim, S; Lombardo, M P; Oktay, M B; Ryan, S M; Sinclair, D K; Skullerud, J-I

2011-02-11

We study the temperature dependence of bottomonium for temperatures in the range 0.4T(c) < T < 2.1T(c), using nonrelativistic dynamics for the bottom quark and full relativistic lattice QCD simulations for Nf = 2 light flavors on a highly anisotropic lattice. We find that the Υ is insensitive to the temperature in this range, while the χb propagators show a crossover from the exponential decay characterizing the hadronic phase to a power-law behavior consistent with nearly free dynamics at T ≃ 2T(c).

Methane and hydrogen ignition with ethanol and butanol admixtures

NASA Astrophysics Data System (ADS)

Eremin, A. V.; Matveeva, N. A.; Mikheyeva, E. Yu

2018-01-01

This work is devoted to the investigation of combustion of simple and complex gaseous fuels: methane and hydrogen with admixtures of the most promising alcohols: ethanol and butanol. The process of ignition of investigated blends behind reflected shock waves in the temperature range of 1000-1600 K and pressure range of 4.5-6 bar was studied. The temperature dependences of ignition delay times for stoichiometric methane-oxygen-ethanol (or butanol) and hydrogen-oxygen-ethanol (or butanol) mixtures diluted in argon were obtained. The possible kinetic description is discussed.

Magnetoresistors as a tool for investigating the mechanical properties of ferromagnetic materials

NASA Astrophysics Data System (ADS)

Kaleta, Jerzy; Tumański, Slawomir; Żebracki, Jacek

1996-07-01

We have investigated the possibility of applying the Villari effect for measurements of the dependence of deformation on the external loading. The magnetic field arising due to the deformation has been measured with a Permalloy magnetoresistive sensor. The plot of the dependence of the external field H on the strain ɛ agrees almost perfectly with the classical dependence σ = f( ɛ) in tensile tests. In steel and nickel samples stress changes in the range 0-500 MPa were accompanied by changes in the external magnetic field in the range 0-300 A/m.

The role of electrostatics in protein-protein interactions of a monoclonal antibody.

PubMed

Roberts, D; Keeling, R; Tracka, M; van der Walle, C F; Uddin, S; Warwicker, J; Curtis, R

2014-07-07

Understanding how protein-protein interactions depend on the choice of buffer, salt, ionic strength, and pH is needed to have better control over protein solution behavior. Here, we have characterized the pH and ionic strength dependence of protein-protein interactions in terms of an interaction parameter kD obtained from dynamic light scattering and the osmotic second virial coefficient B22 measured by static light scattering. A simplified protein-protein interaction model based on a Baxter adhesive potential and an electric double layer force is used to separate out the contributions of longer-ranged electrostatic interactions from short-ranged attractive forces. The ionic strength dependence of protein-protein interactions for solutions at pH 6.5 and below can be accurately captured using a Deryaguin-Landau-Verwey-Overbeek (DLVO) potential to describe the double layer forces. In solutions at pH 9, attractive electrostatics occur over the ionic strength range of 5-275 mM. At intermediate pH values (7.25 to 8.5), there is a crossover effect characterized by a nonmonotonic ionic strength dependence of protein-protein interactions, which can be rationalized by the competing effects of long-ranged repulsive double layer forces at low ionic strength and a shorter ranged electrostatic attraction, which dominates above a critical ionic strength. The change of interactions from repulsive to attractive indicates a concomitant change in the angular dependence of protein-protein interaction from isotropic to anisotropic. In the second part of the paper, we show how the Baxter adhesive potential can be used to predict values of kD from fitting to B22 measurements, thus providing a molecular basis for the linear correlation between the two protein-protein interaction parameters.

Chemical potential dependence of particle ratios within a unified thermal approach

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

Bashir, I., E-mail: inamhep@gmail.com; Nanda, H.; Uddin, S.

2016-06-15

A unified statistical thermal freeze-out model (USTFM) is used to study the chemical potential dependence of identified particle ratios at mid-rapidity in heavy-ion collisions. We successfully reproduce the experimental data ranging from SPS energies to LHC energies, suggesting the statistical nature of the particle production in these collisions and hence the validity of our approach. The behavior of the freeze-out temperature is studied with respect to chemical potential. The freeze-out temperature is found to be universal at the RHIC and LHC and is close to the QCD predicted phase transition temperature, suggesting that the chemical freeze-out occurs soon after themore » hadronization takes place.« less

[Neuropsychological studies of the gnostic processes in children with various forms of infantile cerebral palsy].

PubMed

Mamaĭchuk, I I

1992-01-01

Psychometric and neuropsychological studies were carried out in 182 patients with three forms of infantile cerebral paralysis (ICP). Of these, 112 children presented with spastic diplegia, 50 with hemiparetic diplegia, and 20 with hyperkinetic diplegia. The children's age ranged from 8 to 14 years. Depending on the form of ICP, the structural characteristics of intellect were defined as were specific features of the development of higher cortical functions depending on the localization of the underdevelopment of different brain areas. The classification of the structure of the disorders with the aid of the methods used makes it possible to have a differentiated approach to the medical and pedagogical correction of those patients.

Experimental study of low-energy charge transfer in nitrogen

NASA Technical Reports Server (NTRS)

Smith, A.

1979-01-01

Total charge transfer cross sections were obtained for the N2(+)-N2 system with relative translational ion energies between 9 and 441 eV. Data were obtained to examine the dependence of total cross section on ion energy. The effect of ion excitation on the cross sections was studied by varying the electron ionization energy in the mass spectrometer ion source over an electron energy range between 14.5 and 32.1 eV. The dependence of total cross section on the neutralization chamber gas pressure was examined by obtaining data at pressure values from 9.9 to 0.000199 torr. Cross section values obtained were compared with experimental and theoretical results of other investigations.

Low-temperature study of neutral and charged excitons in the large-area monolayer WS2

NASA Astrophysics Data System (ADS)

Gu, Hong; Chen, Le; Lu, Youming; Tian, Feifei; Zhang, Zhiqiang; Xu, Ke; Wu, Jing; Divakar Botcha, V.; Li, Kuilong; Liu, Xinke

2018-06-01

We present a low-temperature optical study of the large-area monolayer WS2 grown by chemical vapor deposition (CVD). Power-dependent photoluminescence (PL) measurements were conducted, and temperature-dependent PL spectra were measured in the range of 3 to 300 K. With the comparative PL bands obtained, a stronger trion emission in the edge region was detected to be the key difference. Sulfur vacancies (SVs) were observed to increase in density along the growth direction and found to be the main source of the large population of local charge carriers. The monolayer WS2 exhibited an upper bound for the trion binding energy of 18 meV in the edge region.

Concentration Dependent Electrical Transport Properties of Ni-Cr Binary Alloys

NASA Astrophysics Data System (ADS)

Suthar, P. H.; Khambholja, S. G.; Thakore, B. Y.; Gajjar, P. N.; Jani, A. R.

2011-07-01

The concentration dependent electrical transport properties viz. electrical resistivity and thermal conductivity of liquid Ni-Cr alloys are computed at 1400 K temperature. The electrical resistivity has been studied according to Faber-Ziman model in wide range of Cr concentration. In the present work, the electron-ion interaction is incorporated through our well tested local model potential with screening function due to Sarkar et al.. [S] along with the Hartree [H] dielectric function. Good agreement is achieved between the presently calculated results of resistivity as well as thermal conductivity with the experimental data found in the literature, confirming the applicability of model potential and Faber-Ziman model for such a study.

Proximity fuze

DOEpatents

Harrison, Thomas R.

1989-08-22

A proximity fuze system includes an optical ranging apparatus, a detonation circuit controlled by the optical ranging apparatus, and an explosive charge detonated by the detonation cirtcuit. The optical ranging apparatus includes a pulsed laser light source for generating target ranging light pulses and optical reference light pulses. A single lens directs ranging pulses to a target and collects reflected light from the target. An optical fiber bundle is used for delaying the optical reference pulses to correspond to a predetermined distance from the target. The optical ranging apparatus includes circuitry for providing a first signal depending upon the light pulses reflected from the target, a second signal depending upon the light pulses from the optical delay fiber bundle, and an output signal when the first and second signals coincide with each other. The output signal occurs when the distance from the target is equal to the predetermined distance form the target. Additional circuitry distinguishes pulses reflected from the target from background solar radiation.

Combining Density Functional Theory and Green's Function Theory: Range-Separated, Nonlocal, Dynamic, and Orbital-Dependent Hybrid Functional.

PubMed

Kananenka, Alexei A; Zgid, Dominika

2017-11-14

We present a rigorous framework which combines single-particle Green's function theory with density functional theory based on a separation of electron-electron interactions into short- and long-range components. Short-range contribution to the total energy and exchange-correlation potential is provided by a density functional approximation, while the long-range contribution is calculated using an explicit many-body Green's function method. Such a hybrid results in a nonlocal, dynamic, and orbital-dependent exchange-correlation functional of a single-particle Green's function. In particular, we present a range-separated hybrid functional called srSVWN5-lrGF2 which combines the local-density approximation and the second-order Green's function theory. We illustrate that similarly to density functional approximations, the new functional is weakly basis-set dependent. Furthermore, it offers an improved description of the short-range dynamic correlation. The many-body contribution to the functional mitigates the many-electron self-interaction error present in many density functional approximations and provides a better description of molecular properties. Additionally, we illustrate that the new functional can be used to scale down the self-energy and, therefore, introduce an additional sparsity to the self-energy matrix that in the future can be exploited in calculations for large molecules or periodic systems.

Static and dynamic characteristics of a piezoceramic strut

NASA Technical Reports Server (NTRS)

Pokines, Brett J.; Belvin, W. Keith; Inman, Daniel J.

1993-01-01

The experimental study of a piezoceramic active truss is presented. This active strut is unique in that the piezoceramic configurations allow the stroke length of the strut not to be dependent on the piezoceramic material's expansion range but on the deflection range of the piezoceramic bender segment. A finite element model of a piezoceramic strut segment was constructed. Piezoceramic actuation was simulated using thermally induced strains. This model yielded information on the stiffness and force range of a bender element. The static and dynamic properties of the strut were identified experimentally. Feedback control was used to vary the stiffness of the strut. The experimentally verified model was used to explore implementation possibilities of the strut.

Injection-locking of terahertz quantum cascade lasers up to 35GHz using RF amplitude modulation.

PubMed

Gellie, Pierre; Barbieri, Stefano; Lampin, Jean-François; Filloux, Pascal; Manquest, Christophe; Sirtori, Carlo; Sagnes, Isabelle; Khanna, Suraj P; Linfield, Edmund H; Davies, A Giles; Beere, Harvey; Ritchie, David

2010-09-27

We demonstrate that the cavity resonance frequency - the round-trip frequency - of Terahertz quantum cascade lasers can be injection-locked by direct modulation of the bias current using an RF source. Metal-metal and single-plasmon waveguide devices with roundtrip frequencies up to 35GHz have been studied, and show locking ranges above 200MHz. Inside this locking range the laser round-trip frequency is phase-locked, with a phase noise determined by the RF-synthesizer. We find a square-root dependence of the locking range with RF-power in agreement with classical injection-locking theory. These results are discussed in the context of mode-locking operation.

A Summary of the Results of a Study of Acoustic Bottom Interaction in a Range Dependent Environment.

DTIC Science & Technology

1980-11-14

8217 X4v~;i~Q2 \\ ’.X-C 0 fn 0K I ’ ........ .Y A J..~ a~ ~~A’, ~ l ~If U.- A4 UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (When Date Entered) REPORT...Propagation Loss versus Range for Bottom Slopes of 1 and 30 50 111.15 Downslope Propagation Loss versus Range for Bottom Slopes of l and 30 52 111.16...given by l (z,r;zo,r) = 10 logIip (z,r) 12 (2.11) i1 In Eq. (2.11) I is the propagation loss between the field point (z,r) and a point source at (zo,r

Temperature dependence of the electrode kinetics of oxygen reduction at the platinum/Nafion interface - A microelectrode investigation

NASA Technical Reports Server (NTRS)

Parthasarathy, Arvind; Srinivasan, Supramanian; Appleby, A. J.; Martin, Charles R.

1992-01-01

Results of a study of the temperature dependence of the oxygen reduction kinetics at the Pt/Nafion interface are presented. This study was carried out in the temperature range of 30-80 C and at 5 atm of oxygen pressure. The results showed a linear increase of the Tafel slope with temperature in the low current density region, but the Tafel slope was found to be independent of temperature in the high current density region. The values of the activation energy for oxygen reduction at the platinum/Nafion interface are nearly the same as those obtained at the platinum/trifluoromethane sulfonic acid interface but less than values obtained at the Pt/H3PO4 and Pt/HClO4 interfaces. The diffusion coefficient of oxygen in Nafion increases with temperature while its solubility decreases with temperature. These temperatures also depend on the water content of the membrane.

Magnetic relaxation phenomena in the chiral magnet Fe1 -xCoxSi : An ac susceptibility study

NASA Astrophysics Data System (ADS)

Bannenberg, L. J.; Lefering, A. J. E.; Kakurai, K.; Onose, Y.; Endoh, Y.; Tokura, Y.; Pappas, C.

2016-10-01

We present a systematic study of the ac susceptibility of the chiral magnet Fe1 -xCoxSi with x =0.30 covering four orders of magnitude in frequencies from 0.1 Hz to 1 kHz, with particular emphasis to the pronounced history dependence. Characteristic relaxation times ranging from a few milliseconds to tens of seconds are observed around the skyrmion lattice A phase, the helical-to-conical transition and in a region above TC. The distribution of relaxation frequencies around the A phase is broad, asymmetric, and originates from multiple coexisting relaxation processes. The pronounced dependence of the magnetic phase diagram on the magnetic history and cooling rates as well as the asymmetric frequency dependence and slow dynamics suggest more complicated physical phenomena in Fe0.7Co0.3Si than in other chiral magnets.

Influence of lorcainide on microsomal Na+, K(+)-ATPase in guinea-pig isolated heart preparations.

PubMed Central

Almotrefi, A. A.; Dzimiri, N.

1991-01-01

1. The effects of lorcainide on the myocardial Mg2(+)-dependent, Na+ and K(+)-activated adenosine triphosphatase (Na+, K(+)-ATPase) were compared in guinea-pig heart preparations with those of ouabain, a specific inhibitor of the enzyme activity. 2. Both ouabain and lorcainide inhibited the microsomal Na+, K(+)-ATPase activity in a concentration-dependent fashion. Their inhibitory effective ranges were 0.05-100 microM and 0.15-125 microM, respectively, and the concentrations for half maximal inhibition (IC50 values) were 2.1 +/- 0.3 and 33.5 +/- 7.3 microM, respectively. 3. In a second series of experiments, the combined effects of the two drugs on the enzyme activity were studied. In these experiments, lorcainide produced a concentration-dependent potentiation of the inhibitory effects of ouabain on Na+, K(+)-ATPase activity. 4. The present study demonstrates that lorcainide is a potent inhibitor of myocardial Na+, K(+)-ATPase. PMID:1849773

Validation of a multiplex electrochemiluminescent immunoassay platform in human and mouse samples

PubMed Central

Bastarache, J.A.; Koyama, T.; Wickersham, N.E; Ware, L.B.

2014-01-01

Despite the widespread use of multiplex immunoassays, there are very few scientific reports that test the accuracy and reliability of a platform prior to publication of experimental data. Our laboratory has previously demonstrated the need for new assay platform validation prior to use of biologic samples from large studies in order to optimize sample handling and assay performance. In this study, our goal was to test the accuracy and reproducibility of an electrochemiluminescent multiplex immunoassay platform (Meso Scale Discovery, MSD®) and compare this platform to validated, singleplex immunoassays (R&D Systems®) using actual study subject (human plasma and mouse bronchoalveolar lavage fluid (BALF) and plasma) samples. We found that the MSD platform performed well on intra- and inter-assay comparisons, spike and recovery and cross-platform comparisons. The mean intra-assay CV% and range for MSD was 3.49 (0.0-10.4) for IL-6 and 2.04 (0.1-7.9) for IL-8. The correlation between values for identical samples measured on both MSD and R&D was R=0.97 for both analytes. The mouse MSD assay had a broader range of CV% with means ranging from 9.5-28.5 depending on the analyte. The range of mean CV% was similar for single plex ELISAs at 4.3-23.7 depending on the analyte. Regardless of species or sample type, CV% was more variable at lower protein concentrations. In conclusion, we validated a multiplex electrochemiluminscent assay system and found that it has superior test characteristics in human plasma compared to mouse BALF and plasma. Both human and MSD assays compared favorably to well-validated singleplex ELISA's PMID:24768796

Co-evolution of payoff strategy and interaction strategy in prisoner's dilemma game

NASA Astrophysics Data System (ADS)

Zhang, Kangjie; Cheng, Hongyan

2016-11-01

Co-evolutionary dynamical models, providing a realistic paradigm for investigating complex system, have been extensively studied. In this paper, the co-evolution of payoff strategy and interaction strategy is studied. Starting with an initial Gaussian distribution of payoff strategy r with the mean u and the variance q, we focus on the final distribution of the payoff strategy. We find that final distribution of the payoff strategy may display different structures depending on parameters. In the ranges u < - 1 and u > 3, the distribution displays a single-peak structure which is symmetric about r = u. The distribution manifests itself as a double-peak structure in the range - 1 < u < 3 although a fake three-peak structure shows up in range 1 < u < 2. The explanations on the formation of different types of payoff strategy distributions are presented.

Extended law of corresponding states in short-range square wells: a potential energy landscape study.

PubMed

Foffi, Giuseppe; Sciortino, Francesco

2006-11-01

We study the statistical properties of the potential energy landscape of a system of particles interacting via a very short-range square-well potential (of depth -u0) as a function of the range of attraction Delta to provide thermodynamic insights of the Noro and Frenkel [M. G. Noro and D. Frenkel, J. Chem. Phys. 113, 2941 (2000)] scaling. We exactly evaluate the basin free energy and show that it can be separated into a vibrational (Delta dependent) and a floppy (Delta independent) component. We also show that the partition function is a function of Deltaebetauo, explaining the equivalence of the thermodynamics for systems characterized by the same second virial coefficient. An outcome of our approach is the possibility of counting the number of floppy modes (and their entropy).

Treatment consumption and treatment re-enrollment in GHB-dependent patients in The Netherlands.

PubMed

van Noorden, Martijn S; Mol, Ton; Wisselink, Jeroen; Kuijpers, Wil; Dijkstra, Boukje A G

2017-07-01

The objective of this study was to assess treatment consumption and re-enrollment in treatment in patients with gamma-hydroxybutyrate (GHB)-dependence in Dutch Addiction Treatment Centers (ATCs) in comparison with other addictions. A cohort-study using nationwide administrative data from regular Dutch ATCs associated with the Dutch National Alcohol and Drugs Information System (LADIS), covering an estimated 95% of ATCs. We selected in- and out-patients with alcohol, drug and/or behavioral addictions with a first treatment episode in 2008-2011 and consecutive treatments until 2013 (n=71,679). Patients still in treatment at that date (n=3686; 5.1%), forensic patients (n=1949; 2.7%) and deceased patients (n=570; 0.8%) were excluded, leaving 65,474 patients (91.3%). Of those, 596 (0.9%) patients had GHB dependence. We analyzed number of treatment contacts, treatment duration, admissions and admission duration of the first treatment episode, and re-enrollment (defined as having started a second treatment episode in the study period). GHB-dependent patients showed the highest number of treatment contacts, duration of treatment and chance of being admitted. Re-enrollment rates were 2-5 times higher in GHB-dependent patients than other patients with adjusted HR of other addictions ranging from 0.18 (95% confidence interval [CI]: 0.15-0.21) to 0.53 (95% CI: 0.47-0.61). This study demonstrates high levels of treatment consumption and high rates of treatment re-enrollment in GHB-dependent patients. These findings highlight the urgency of developing effective relapse prevention interventions for GHB-dependent patients. Copyright © 2017 Elsevier B.V. All rights reserved.

Critical role for hierarchical geospatial analyses in the design of fluvial research, assessment, and management

EPA Science Inventory

River science and management can be conducted at a range of spatiotemporal scales from reach to basin levels as long as the project goals and questions are matched correctly with the study design’s spatiotemporal scales and dependent variables. These project goals should also inc...

Sinks for nitrogen inputs in terrestrial ecosystems: A meta-analysis of 15N tracer field studies

EPA Science Inventory

Anthropogenic nitrogen (N) deposition can have a range of effects on terrestrial ecosystems, but these effects depend in part on the fate of this deposited N, particularly in the amount retained or lost from the system, and in the partitioning of retained N between plants and soi...

Age-Related Differences in Moral Identity across Adulthood

ERIC Educational Resources Information Center

Krettenauer, Tobias; Murua, Lourdes Andrea; Jia, Fanli

2016-01-01

In this study, age-related differences in adults' moral identity were investigated. Moral identity was conceptualized a context-dependent self-structure that becomes differentiated and (re)integrated in the course of development and that involves a broad range of value-orientations. Based on a cross-sectional sample of 252 participants aged 14 to…

Prevalence, Types and Determinants of Complementary and Alternative Medications among Health Clinic Clients

ERIC Educational Resources Information Center

Almousa, H.; Rabie, Faten M.; Alsamghan, Awad S.; Alsaluli, Mobarak; Albqami, Sultan; Almusa, Mona; Al-shahrani, Areej

2015-01-01

Complementary and Alternative Medicine (CAM) covers a wide range of over 100 healing approaches, philosophies and therapeutic modalities that are not provided by conventional medicine. Objectives: The study was aimed at identifying the prevalence, types and determinants of CAM use, sources of information about CAM that patients usually depend upon…

The role of aquaporins in pH-Dependent germination of Rhizopus delemar spores

USDA-ARS?s Scientific Manuscript database

Rhizopus delemar and associated species attack a wide range of fruit and vegetables after harvest. Host nutrients and acidic pH are required for optimal germination of R. delemar, and we studied how this process is triggered. Glucose induced spore swelling in an acidic environment, expressed by an u...

Employers' Views on the Value of Older Workers. Final Report.

ERIC Educational Resources Information Center

University of Southern Maine, Portland. Human Services Development Inst.

A study examined the extent to which organizations in three New England states valued newly hired older workers. Telephone interviews were conducted with 105 directors of human resources (DHRs) and with 113 director supervisors from a broad range of organizations. Major dependent variables were general employer motivations and expectations related…

EVALUATING TOOLS AND MODELS USED FOR QUANTITATIVE EXTRAPOLATION OF IN VITRO TO IN VIVO DATA FOR NEUROTOXICANTS*

EPA Science Inventory

There are a number of risk management decisions, which range from prioritization for testing to quantitative risk assessments. The utility of in vitro studies in these decisions depends on how well the results of such data can be qualitatively and quantitatively extrapolated to i...

Sensing Surveillance & Navigation

DTIC Science & Technology

2012-03-07

Removing Atmospheric Turbulence Goal: to restore a single high quality image from the observed sequence Prof. Peyman...Computer Sciences – Higher wavelet studies , time-scale, time-frequency transformations, Reduced Signature Targets, Low Probability of Intercept...Range Dependent Beam -patterns •Electronic Steering with Frequency Offsets •Inherent Countermeasure Capability Why? W1(t) W2(t) W3

Theoretical and experimental study of AC electrical conduction mechanism in the low temperature range of p-CuIn3Se5

NASA Astrophysics Data System (ADS)

Essaleh, L.; Amhil, S.; Wasim, S. M.; Marín, G.; Choukri, E.; Hajji, L.

2018-05-01

In the present work, an attempt has been made to study theoretically and experimentally the AC electrical conduction mechanism in disordered semiconducting materials. The key parameter considered in this analysis is the frequency exponent s(ω , T) =( ∂ln(σAC(ω , T))/∂ ln(ω)T , where σAC is the AC electrical conductivity that depends on angular frequency ω and temperature T. In the theoretical part of this work, the effect of the barrier hopping energy, the polaron radius and the characteristic relaxation time is considered. The theoretical models of Quantum Mechanical Tunneling (QMT), Non overlapping Small Polaron Tunneling (NSPT), Overlapping Large Polaron Tunneling (OLPT) and Correlated Barrier Hopping (CBH) are considered to fit experimental data of σAC in p-CuIn3Se5 (p-CIS135) in the low temperature range up to 96 K. Some important parameters, as the polaron radius, the localization length and the barrier hopping energies, are estimated and their temperature and frequency dependence discussed.

Ecotypic differentiation matters for latitudinal variation in energy metabolism and flight performance in a butterfly under climate change.

PubMed

Van Dyck, Hans; Holveck, Marie-Jeanne

2016-11-15

Life histories of organisms may vary with latitude as they experience different thermal constraints and challenges. This geographic, intraspecific variation could be of significance for range dynamics under climate change beyond edge-core comparisons. In this study, we did a reciprocal transplant experiment between the temperature-regimes of two latitudes with an ectotherm insect, examining the effects on energy metabolism and flight performance. Pararge aegeria expanded its ecological niche from cool woodland (ancestral) to warmer habitat in agricultural landscape (novel ecotype). Northern males had higher standard metabolic rates than southern males, but in females these rates depended on their ecotype. Southern males flew for longer than northern ones. In females, body mass-corrected flight performance depended on latitude and thermal treatment during larval development and in case of the southern females, their interaction. Our experimental study provides evidence for the role of ecological differentiation at the core of the range to modulate ecophysiology and flight performance at different latitudes, which in turn may affect the climatic responsiveness of the species.

Ecotypic differentiation matters for latitudinal variation in energy metabolism and flight performance in a butterfly under climate change

PubMed Central

Van Dyck, Hans; Holveck, Marie-Jeanne

2016-01-01

Life histories of organisms may vary with latitude as they experience different thermal constraints and challenges. This geographic, intraspecific variation could be of significance for range dynamics under climate change beyond edge-core comparisons. In this study, we did a reciprocal transplant experiment between the temperature-regimes of two latitudes with an ectotherm insect, examining the effects on energy metabolism and flight performance. Pararge aegeria expanded its ecological niche from cool woodland (ancestral) to warmer habitat in agricultural landscape (novel ecotype). Northern males had higher standard metabolic rates than southern males, but in females these rates depended on their ecotype. Southern males flew for longer than northern ones. In females, body mass-corrected flight performance depended on latitude and thermal treatment during larval development and in case of the southern females, their interaction. Our experimental study provides evidence for the role of ecological differentiation at the core of the range to modulate ecophysiology and flight performance at different latitudes, which in turn may affect the climatic responsiveness of the species. PMID:27845372

High temperature dielectric studies of indium-substituted NiCuZn nanoferrites

NASA Astrophysics Data System (ADS)

Hashim, Mohd.; Raghasudha, M.; Shah, Jyoti; Shirsath, Sagar E.; Ravinder, D.; Kumar, Shalendra; Meena, Sher Singh; Bhatt, Pramod; Alimuddin; Kumar, Ravi; Kotnala, R. K.

2018-01-01

In this study, indium (In3+)-substituted NiCuZn nanostructured ceramic ferrites with a chemical composition of Ni0.5Cu0.25Zn0.25Fe2-xInxO4 (0.0 ≤ x ≤ 0.5) were prepared by chemical synthesis involving sol-gel chemistry. Single phased cubic spinel structure materials were prepared successfully according to X-ray diffraction and transmission electron microscopy analyses. The dielectric properties of the prepared ferrites were measured using an LCR HiTester at temperatures ranging from room temperature to 300 °C at different frequencies from 102 Hz to 5 × 106 Hz. The variations in the dielectric parameters ε‧ and (tanδ) with temperature demonstrated the frequency- and temperature-dependent characteristics due to electron hopping between the ions. The materials had low dielectric loss values in the high frequency range at all temperatures, which makes them suitable for high frequency microwave applications. A qualitative explanation is provided for the dependences of the dielectric constant and dielectric loss tangent on the frequency, temperature, and composition. Mӧssbauer spectroscopy was employed at room temperature to characterize the magnetic behavior.

Effect of Trace Levels of Si on Microstructure and Grain Boundary Segregation in DOP-26 Iridium Alloy

NASA Astrophysics Data System (ADS)

Pierce, Dean; Muralidharan, Govindarajan; Heatherly, Lee; Fox, Ethan

2018-03-01

The thermodynamics and kinetics of Silicon (Si) segregation to grain boundaries in Iridium alloy DOP-26 with added trace levels of Si of 6, 11, 29, and 36 wppm was studied by Auger Electron Spectroscopy. The four alloys were annealed at 1500 or 1535 °C for 19 or 76 hours followed by cooling at three different rates. Si enrichment at the grain boundaries (GB) increased with increasing bulk Si content, with the grain boundary Si enrichment factors ranging from 62 to 344, depending on the bulk Si content and the cooling rate. Grain boundary Si contents increased with decreasing cooling rate in all alloys, indicating that Si GB segregation is influenced by both thermodynamic and kinetic factors in the alloys and temperature ranges of the study. A Langmuir-McLean isotherm-based model was successfully used to predict the temperature dependence of GB Si segregation in DOP-26 alloys with Si additions and estimate the temperature independent free energy of Si segregation to grain boundaries in DOP-26.

Temperature effects on snapping performance in the common snapper Chelydra serpentina (Reptilia, Testudines).

PubMed

Vervust, Bart; Brecko, Jonathan; Herrel, Anthony

2011-01-01

Studies on the effect of temperature on whole-animal performance traits other than locomotion are rare. Here we investigate the effects of temperature on the performance of the turtle feeding apparatus in a defensive context. We measured bite force and the kinematics of snapping in the Common Snapping Turtle (Chelydra serpentina) over a wide range of body temperatures. Bite force performance was thermally insensitive over the broad range of temperatures typically experienced by these turtles in nature. In contrast, neck extension (velocity, acceleration, and deceleration) and jaw movements (velocity, acceleration, and deceleration) showed clear temperature dependence with peak acceleration and deceleration capacity increasing with increasing temperatures. Our results regarding the temperature dependence of defensive behavior are reflected by the ecology and overall behavior of this species. These data illustrate the necessity for carefully controlling T(b) when carrying out behavioral and functional studies on turtles as temperature affects the velocity, acceleration, and deceleration of jaw and neck extension movements. More generally, these data add to the limited but increasing number of studies showing that temperature may have important effects on feeding and defensive performance in ectotherms. © 2010 Wiley-Liss, Inc.

Defect specific luminescence dead layers in CdS and CdSe

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

Rosenberg, R. A.

CdS and CdSe are often used in optoelectronic devices whose effectiveness is may be dictated by defects in the near surface region. Luminescence is one of the main tools for studying such defects. The energy dependence of the x-ray excited optical luminescence (XEOL) spectra of these materials enables the extraction of the depth dependence of the defect distribution. Normal and time-gated XEOL spectra were obtained from these materials in the energy range 600 to 1500 eV. Here, we find that the results can best be understood in terms of a luminescence dead layer whose width depends on the position ofmore » the defect level in the band gap.« less

Defect specific luminescence dead layers in CdS and CdSe

DOE PAGES

Rosenberg, R. A.

2017-04-28

CdS and CdSe are often used in optoelectronic devices whose effectiveness is may be dictated by defects in the near surface region. Luminescence is one of the main tools for studying such defects. The energy dependence of the x-ray excited optical luminescence (XEOL) spectra of these materials enables the extraction of the depth dependence of the defect distribution. Normal and time-gated XEOL spectra were obtained from these materials in the energy range 600 to 1500 eV. Here, we find that the results can best be understood in terms of a luminescence dead layer whose width depends on the position ofmore » the defect level in the band gap.« less

A Self-Referencing Intensity Based Polymer Optical Fiber Sensor for Liquid Detection

PubMed Central

Montero, David Sánchez; Vázquez, Carmen; Möllers, Ingo; Arrúe, Jon; Jäger, Dieter

2009-01-01

A novel self-referencing fiber optic intensity sensor based on bending losses of a partially polished polymer optical fiber (POF) coupler is presented. The coupling ratio (K) depends on the external liquid in which the sensor is immersed. It is possible to distinguish between different liquids and to detect their presence. Experimental results for the most usual liquids found in industry, like water and oil, are given. K value increases up to 10% from the nominal value depending on the liquid. Sensor temperature dependence has also been studied for a range from 25 °C (environmental condition) to 50 °C. Any sector requiring liquid level measurements in flammable atmospheres can benefit from this intrinsically safe technology. PMID:22454594

Hydrogen absorption and its effect on magnetic properties of Nd2Fe14B

NASA Astrophysics Data System (ADS)

Bezdushnyi, R.; Damianova, R.; Tereshina, I. S.; Pankratov, N. Yu.; Nikitin, S. A.

2018-05-01

Magnetic properties of hydrides of the intermetallic compound Nd2Fe14BHx are investigated in the temperature range covering the Curie temperatures (TC) of the compounds (up to 670 K). The temperature dependencies of magnetization are measured under continuous control of hydrogen content in the investigated samples. The dependencies of Curie and spin-reorientation transition (TSR) temperatures on the hydrogen concentration are studied in detail. The dependence of hydrogen concentration on pressure at a constant temperature (near TC) and on the temperature at various pressures are obtained. We attempted to estimate the contributions of the unit cell volume increase upon hydrogenation and the electronic structure change in the variation of TC of the hydrogenated Nd2Fe14 B .

Optical gain characteristics of C 460 and C 450.

PubMed

Sharma, Vijay K; Sahare, P D; Pandey, A; Mohan, D

2003-03-15

Dye concentration dependent gain spectra for Coumarin 460 (C 460) and Coumarin 450 (C 450) in ethanol have been studied using Amplified Spontaneous Emission (ASE) technique under Nitrogen laser (337.1 nm) excitation in the concentration range 10(-2)-10(-5) m/l. The dependence of lasing wavelength and peak gain on concentration have been understood in terms of variation of fluorescence lifetime, which is due to photo-physical processes such as radiation trapping and concentration-quenching. Pump intensity dependence of efficiency is also explained in terms of fluorescence lifetime. A comparison of the stability of the two dyes has also been made on the basis of the functional groups at different positions of the basic coumarin. Copyright 2002 Elsevier Science B.V.

Recent Line-Shape and Doppler Thermometry Studies Involving Transitions in the ν1 +ν3 Band of Acetylene

NASA Astrophysics Data System (ADS)

Hashemi, Robab; Rozario, Hoimonti; Povey, Chad; Garber, Jolene; Derksen, Mark; Predoi-Cross, Adriana

2014-06-01

The line positions for transitions in the ν1 +ν3 band are often used as a frequency standard by the telecom industry and also needed for planetary atmospheric studies. Four relevant studies have been recently carried out in our group and will be discussed briefly below. (1) N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the ν1 +ν3 band of acetylene at seven temperatures in the range 213333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters. This study has been published in Molecular Physics, 110 Issue 21/22 (2012) 2645-2663. (2) Six nitrogen perturbed transitions of acetylene within the ν1 +ν3 absorption band have been recorded using a 3-channel diode laser spectrometer. We have examined C2H2 spectra using a hard collision (Rautian) profile over a range of five temperatures (213 K-333 K). From these fits we have obtained the N2-broadening and narrowing coefficients of C2H2 and examined their temperature dependence. The experimentally measured narrowing coefficients have been used to estimate the nitrogen diffusion coefficients. The broadening coefficients and corresponding temperature dependence exponents have also been compared to that of calculations completed using a classical impact approach on an ab initio potential energy surface. We have observed a good agreement between our theoretical and experimental results. This study was published in Canadian Journal of Physics 91(11) 896-905 (2013). (3) An extension of the previous study was to analyze the room temperature for the same six transitions using the Voigt, Rautian, Galatry, RautianGalatry and Correlated Rautian profiles. For the entire pressure range, we have tested the applicability of these line-shape models. Except for Voigt profile, Dicke narrowing effect has been considered in all mentioned line-shape models. The experimental results for the narrowing parameters have been compared with calculated values based on the theory of diffusion. This study is in press in press in the Journal of Quantitative Spectroscopy and Radiative Transfer. (4) In this paper we present accurate measurements of the fundamental Boltzmann constant based on a lineshape analysis of acetylene spectra in the ν1 +ν3 band recorded using a tunable diode laser. Experimental spectra recorded at low pressures have been analyzed using both the Voigt model and the Speed Dependent Voigt model that takes into account the molecular speed dependence effects. These line-shape models reproduces the experimental data with high accuracy and allow us to determine precise line-shape parameters for the transitions used, the Doppler-width and then determined the Boltzmann constant, kB. This study has been submitted for publication in the Journal of Chemical Physics. 1 1 Research described in this work was funded by NSERC, Canada.

Timescale- and Sensory Modality-Dependency of the Central Tendency of Time Perception.

PubMed

Murai, Yuki; Yotsumoto, Yuko

2016-01-01

When individuals are asked to reproduce intervals of stimuli that are intermixedly presented at various times, longer intervals are often underestimated and shorter intervals overestimated. This phenomenon may be attributed to the central tendency of time perception, and suggests that our brain optimally encodes a stimulus interval based on current stimulus input and prior knowledge of the distribution of stimulus intervals. Two distinct systems are thought to be recruited in the perception of sub- and supra-second intervals. Sub-second timing is subject to local sensory processing, whereas supra-second timing depends on more centralized mechanisms. To clarify the factors that influence time perception, the present study investigated how both sensory modality and timescale affect the central tendency. In Experiment 1, participants were asked to reproduce sub- or supra-second intervals, defined by visual or auditory stimuli. In the sub-second range, the magnitude of the central tendency was significantly larger for visual intervals compared to auditory intervals, while visual and auditory intervals exhibited a correlated and comparable central tendency in the supra-second range. In Experiment 2, the ability to discriminate sub-second intervals in the reproduction task was controlled across modalities by using an interval discrimination task. Even when the ability to discriminate intervals was controlled, visual intervals exhibited a larger central tendency than auditory intervals in the sub-second range. In addition, the magnitude of the central tendency for visual and auditory sub-second intervals was significantly correlated. These results suggest that a common modality-independent mechanism is responsible for the supra-second central tendency, and that both the modality-dependent and modality-independent components of the timing system contribute to the central tendency in the sub-second range.

Tribo-Mechanical Properties of HVOF Deposited Fe3Al Coatings Reinforced with TiB2 Particles for Wear-Resistant Applications

PubMed Central

Amiriyan, Mahdi; Blais, Carl; Savoie, Sylvio; Schulz, Robert; Gariépy, Mario; Alamdari, Houshang

2016-01-01

This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. PMID:28787917

An Empirical Modification of the Force Field Approach to Describe the Modulation of Galactic Cosmic Rays Close to Earth in a Broad Range of Rigidities

NASA Astrophysics Data System (ADS)

Gieseler, J.; Heber, B.; Herbst, K.

2017-11-01

On their way through the heliosphere, galactic cosmic rays (GCRs) are modulated by various effects before they can be detected at Earth. This process can be described by the Parker equation, which calculates the phase space distribution of GCRs depending on the main modulation processes: convection, drifts, diffusion, and adiabatic energy changes. A first-order approximation of this equation is the force field approach, reducing it to a one-parameter dependency, the solar modulation potential ϕ. Utilizing this approach, it is possible to reconstruct ϕ from ground-based and spacecraft measurements. However, it has been shown previously that ϕ depends not only on the local interstellar spectrum (LIS) but also on the energy range of interest. We have investigated this energy dependence further, using published proton intensity spectra obtained by PAMELA and heavier nuclei measurements from IMP-8 and ACE/CRIS. Our results show severe limitations at lower energies including a strong dependence on the solar magnetic epoch. Based on these findings, we will outline a new tool to describe GCR proton spectra in the energy range from a few hundred MeV to tens of GeV over the last solar cycles. In order to show the importance of our modification, we calculate the global production rates of the cosmogenic radionuclide 10Be which is a proxy for the solar activity ranging back thousands of years.

Rethinking FCV/BEV Vehicle Range: A Consumer Value Trade-off Perspective

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

Lin, Zhenhong; Greene, David L

2010-01-01

The driving range of FCV and BEV is often analyzed by simple analogy to conventional vehicles without proper consideration of differences in energy storage technology, infrastructure, and market context. This study proposes a coherent framework to optimize the driving range by minimizing costs associated with range, including upfront storage cost, fuel availability cost for FCV and range anxiety cost for BEV. It is shown that the conventional assumption of FCV range can lead to overestimation of FCV market barrier by over $8000 per vehicle in the near-term market. Such exaggeration of FCV market barrier can be avoided with range optimization.more » Compared to the optimal BEV range, the 100-mile range chosen by automakers appears to be near optimal for modest drivers, but far less than optimal for frequent drivers. With range optimization, the probability that the BEV is unable to serve a long-trip day is generally less than 5%, depending on driving intensity. Range optimization can help diversify BEV products for different consumers. It is also demonstrated and argued that the FCV/BEV range should adapt to the technology and infrastructure developments.« less