Electronic Structure of Tl2Ba2CuO(6+Delta) Epitaxial Films Measured by X-Ray Photoemission

NASA Technical Reports Server (NTRS)

Vasquez, R. P.; Ren, Z. F.; Wang, J. H.

1996-01-01

The valence electronic structure and core levels of Tl2Ba2CuO(6 + delta) (Tl-2201) epitaxial films have been measured with X-ray photoelectron spectroscopy and are compared to those of Tl2Ba2CaCu2O(8 + delta) (Tl-2212). Changes in the Tl-2201 core-level binding energies with oxygen doping are consistent with a change in the chemical potential. Differences between the Tl-2201 and Tl-2212 measured densities of states are consistent with the calculated Cu 3d and Tl 6s partial densities of states.

NonMarkov Ito Processes with 1- state memory

NASA Astrophysics Data System (ADS)

McCauley, Joseph L.

2010-08-01

A Markov process, by definition, cannot depend on any previous state other than the last observed state. An Ito process implies the Fokker-Planck and Kolmogorov backward time partial differential eqns. for transition densities, which in turn imply the Chapman-Kolmogorov eqn., but without requiring the Markov condition. We present a class of Ito process superficially resembling Markov processes, but with 1-state memory. In finance, such processes would obey the efficient market hypothesis up through the level of pair correlations. These stochastic processes have been mislabeled in recent literature as 'nonlinear Markov processes'. Inspired by Doob and Feller, who pointed out that the ChapmanKolmogorov eqn. is not restricted to Markov processes, we exhibit a Gaussian Ito transition density with 1-state memory in the drift coefficient that satisfies both of Kolmogorov's partial differential eqns. and also the Chapman-Kolmogorov eqn. In addition, we show that three of the examples from McKean's seminal 1966 paper are also nonMarkov Ito processes. Last, we show that the transition density of the generalized Black-Scholes type partial differential eqn. describes a martingale, and satisfies the ChapmanKolmogorov eqn. This leads to the shortest-known proof that the Green function of the Black-Scholes eqn. with variable diffusion coefficient provides the so-called martingale measure of option pricing.

LANDSAT-D data format control book. Volume 6, appendix C: Partially processed multispectral scanner high density tape (HDT-AM)

NASA Technical Reports Server (NTRS)

Andersen, K. E.

1982-01-01

The format of high density tapes which contain partially processed LANDSAT 4 and LANDSAT D prime MSS image data is defined. This format is based on and is compatible with the existing format for partially processed LANDSAT 3 MSS image data HDTs.

Theoretical study of hydrated copper(II) interactions with guanine: a computational density functional theory study.

PubMed

Pavelka, Matej; Shukla, Manoj K; Leszczynski, Jerzy; Burda, Jaroslav V

2008-01-17

Optimization of the hydrated Cu(II)(N7-guanine) structures revealed a number of minima on the potential energy surface. For selected structures, energy decompositions together with the determination of electronic properties (partial charges and electron spin densities) were performed. In the complexes of guanine with the bare copper cation and that with the monoaqua ligated cation, an electron transfer from guanine to Cu(II) was observed, resulting in a Cu(I)-guanine(+) type of complex. Conformers with two aqua ligands are borderline systems characterized by a Cu partial charge of +0.7e and a similar value of the spin density (0.6e) localized on guanine. When tetracoordination of copper was achieved, only then the prevailing electron spin density is unambiguously localized on copper. The energetic preference of diaqua-Cu-(N7,O6-guanine) over triaqua-Cu-(N7-guanine) was found for the four-coordinate structures. However, the energy difference between these two conformations decreases with the number of water molecules present in the systems, and in complexes with five water molecules this preference is preserved only at DeltaG level where thermal and entropy terms are included.

Adjoint-based constant-mass partial derivatives

DOE PAGES

Favorite, Jeffrey A.

2017-09-01

In transport theory, adjoint-based partial derivatives with respect to mass density are constant-volume derivatives. Likewise, adjoint-based partial derivatives with respect to surface locations (i.e., internal interface locations and the outer system boundary) are constant-density derivatives. This study derives the constant-mass partial derivative of a response with respect to an internal interface location or the outer system boundary and the constant-mass partial derivative of a response with respect to the mass density of a region. Numerical results are given for a multiregion two-dimensional (r-z) cylinder for three very different responses: the uncollided gamma-ray flux at an external detector point, k effmore » of the system, and the total neutron leakage. Finally, results from the derived formulas compare extremely well with direct perturbation calculations.« less

Molding cork sheets to complex shapes

NASA Technical Reports Server (NTRS)

Sharpe, M. H.; Simpson, W. G.; Walker, H. M.

1977-01-01

Partially cured cork sheet is easily formed to complex shapes and then final-cured. Temperature and pressure levels required for process depend upon resin system used and final density and strength desired. Sheet can be bonded to surface during final cure, or can be first-formed in mold and bonded to surface in separate step.

Vorticity scaling and intermittency in drift-interchange plasma turbulence

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

Dura, P. D.; Hnat, B.; Robinson, J.

2012-09-15

The effects of spatially varying magnetic field strength on the scaling properties of plasma turbulence, modelled by an extended form of Hasegawa-Wakatani model, are investigated. We study changes in the intermittency of the velocity, density, and vorticity fields, as functions of the magnetic field inhomogeneity C=-{partial_derivative} ln B/{partial_derivative}x. While the velocity fluctuations are always self-similar and their scaling is unaffected by the value of C, the intermittency levels in density and vorticity change with parameter C, reflecting morphological changes in the coherent structures due to the interchange mechanism. Given the centrality of vorticity in conditioning plasma transport, this result ismore » of interest in scaling the results of transport measurements and simulations in tokamak edge plasmas, where drift-interchange turbulence in the presence of a magnetic field gradient is likely to occur.« less

Modeling the Electrode-Neuron Interface of Cochlear Implants: Effects of Neural Survival, Electrode Placement, and the Partial Tripolar Configuration

PubMed Central

Goldwyn, Joshua H.; Bierer, Steven M.; Bierer, Julie A.

2010-01-01

The partial tripolar electrode configuration is a relatively novel stimulation strategies that can generate more spatially focused electric fields than the commonly used monopolar configuration. Focused stimulation strategies should improve spectral resolution in cochlear implant users, but may also be more sensitive to local irregularities in the electrode-neuron interface. In this study, we develop a practical computer model of cochlear implant stimulation that can simulate neural activation in a simplified cochlear geometry and we relate the resulting patterns of neural activity to basic psychophysical measures. We examine how two types of local irregularities in the electrode-neuron interface, variations in spiral ganglion nerve density and electrode position within the scala tympani, affect the simulated neural activation patterns and how these patterns change with electrode configuration. The model shows that higher partial tripolar fractions activate more spatially restricted populations of neurons at all current levels and require higher current levels to excite a given number of neurons. We find that threshold levels are more sensitive at high partial tripolar fractions to both types of irregularities, but these effects are not independent. In particular, at close electrode-neuron distances, activation is typically more spatially localized which leads to a greater influence of neural dead regions. PMID:20580801

Analysis of partial-reflection data from the solar eclipse of 10 Jul. 1972. [ground-based experiment using vertical incident radio waves partially reflected from D region

NASA Technical Reports Server (NTRS)

Bean, T. A.; Bowhill, S. A.

1973-01-01

Partial-reflection data collected for the eclipse of July 10, 1972 as well as for July 9 and 11, 1972, are analyzed to determine eclipse effects on D-region electron densities. The partial-reflection experiment was set up to collect data using an on-line PDP-15 computer and DECtape storage. The electron-density profiles show good agreement with results from other eclipses. The partial-reflection programs were changed after the eclipse data collection to improve the operation of the partial-reflection system. These changes were mainly due to expanded computer hardware and have simplified the operations of the system considerably.

Multiple browsers structure tree recruitment in logged temperate forests

USGS Publications Warehouse

Faison, Edward K.; DeStefano, Stephen; Foster, David R.; Rapp, Joshua M.; Compton, Justin A.

2016-01-01

Historical extirpations have resulted in depauperate large herbivore assemblages in many northern forests. In eastern North America, most forests are inhabited by a single wild ungulate species, white-tailed deer (Odocoileus virginianus), and relationships between deer densities and impacts on forest regeneration are correspondingly well documented. Recent recolonizations by moose (Alces americanus) in northeastern regions complicate established deer density thresholds and predictions of browsing impacts on forest dynamics because size and foraging differences between the two animals suggest a lack of functional redundancy. We asked to what extent low densities of deer + moose would structure forest communities differently from that of low densities of deer in recently logged patch cuts of Massachusetts, USA. In each site, a randomized block with three treatment levels of large herbivores–no-ungulates (full exclosure), deer (partial exclosure), and deer + moose (control) was established. After 6–7 years, deer + moose reduced stem densities and basal area by 2-3-fold, Prunus pensylvanica and Quercus spp. recruitment by 3–6 fold, and species richness by 1.7 species (19%). In contrast, in the partial exclosures, deer had non-significant effects on stem density, basal area, and species composition, but significantly reduced species richness by 2.5 species on average (28%). Deer browsing in the partial exclosure was more selective than deer + moose browsing together, perhaps contributing to the decline in species richness in the former treatment and the lack of additional decline in the latter. Moose used the control plots at roughly the same frequency as deer (as determined by remote camera traps), suggesting that the much larger moose was the dominant browser species in terms of animal biomass in these cuts. A lack of functional redundancy with respect to foraging behavior between sympatric large herbivores may explain combined browsing effects that were both large and complex.

Local density approximation in site-occupation embedding theory

NASA Astrophysics Data System (ADS)

Senjean, Bruno; Tsuchiizu, Masahisa; Robert, Vincent; Fromager, Emmanuel

2017-01-01

Site-occupation embedding theory (SOET) is a density functional theory (DFT)-based method which aims at modelling strongly correlated electrons. It is in principle exact and applicable to model and quantum chemical Hamiltonians. The theory is presented here for the Hubbard Hamiltonian. In contrast to conventional DFT approaches, the site (or orbital) occupations are deduced in SOET from a partially interacting system consisting of one (or more) impurity site(s) and non-interacting bath sites. The correlation energy of the bath is then treated implicitly by means of a site-occupation functional. In this work, we propose a simple impurity-occupation functional approximation based on the two-level (2L) Hubbard model which is referred to as two-level impurity local density approximation (2L-ILDA). Results obtained on a prototypical uniform eight-site Hubbard ring are promising. The extension of the method to larger systems and more sophisticated model Hamiltonians is currently in progress.

Benefits of migration in a partially-migratory tropical ungulate

PubMed Central

2013-01-01

Background Partial migration, where one portion of a population conducts seasonal migrations while the other remains on a single range, is common in wild ungulate populations. However the relative costs and benefits associated with the distinct strategies adopted by coexisting migrant and resident individuals have rarely been investigated. Here we compare the body condition of migrants and residents in a partially migratory population of impalas (Aepyceros melampus) in Zimbabwe. The study was conducted during two consecutive years with highly contrasted population densities (16.4 and 8.6 indiv/km2) due to harvesting. Results We first identify a population substructure with a north–south sub-division in two spatial units related to distinct soils and vegetation cover. Impalas in the north range had a consistently higher diet quality and body condition than those in the south range. At the beginning of the dry season about one third of the individuals migrated from the lower (i.e. south) to the higher (i.e. north) diet quality range. This partial migration pattern was consistent between the consecutive years, and most individuals showed constancy to their moving strategy (migrant or resident). In both years, these migrants had a significantly higher body condition at the end of the dry season than the south residents that remained year-round in the lower diet quality range. Diet quality and body condition of impalas were higher in the year of lower density; however we did not detect any evidence for density-dependence in migration propensity, at the individual or population levels, nor in the benefit associated with migration. Conclusions Our findings provide rare evidence for a significant relationship between body condition and seasonal migration strategy in wild ungulates in relation to a difference in the quality of resources acquired between distinct seasonal ranges. This study also constitutes rare evidence of partial migration in a tropical ungulate population. PMID:24079650

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

Favorite, Jeffrey A.

In transport theory, adjoint-based partial derivatives with respect to mass density are constant-volume derivatives. Likewise, adjoint-based partial derivatives with respect to surface locations (i.e., internal interface locations and the outer system boundary) are constant-density derivatives. This study derives the constant-mass partial derivative of a response with respect to an internal interface location or the outer system boundary and the constant-mass partial derivative of a response with respect to the mass density of a region. Numerical results are given for a multiregion two-dimensional (r-z) cylinder for three very different responses: the uncollided gamma-ray flux at an external detector point, k effmore » of the system, and the total neutron leakage. Finally, results from the derived formulas compare extremely well with direct perturbation calculations.« less

Parallel Newton-Krylov-Schwarz algorithms for the transonic full potential equation

NASA Technical Reports Server (NTRS)

Cai, Xiao-Chuan; Gropp, William D.; Keyes, David E.; Melvin, Robin G.; Young, David P.

1996-01-01

We study parallel two-level overlapping Schwarz algorithms for solving nonlinear finite element problems, in particular, for the full potential equation of aerodynamics discretized in two dimensions with bilinear elements. The overall algorithm, Newton-Krylov-Schwarz (NKS), employs an inexact finite-difference Newton method and a Krylov space iterative method, with a two-level overlapping Schwarz method as a preconditioner. We demonstrate that NKS, combined with a density upwinding continuation strategy for problems with weak shocks, is robust and, economical for this class of mixed elliptic-hyperbolic nonlinear partial differential equations, with proper specification of several parameters. We study upwinding parameters, inner convergence tolerance, coarse grid density, subdomain overlap, and the level of fill-in in the incomplete factorization, and report their effect on numerical convergence rate, overall execution time, and parallel efficiency on a distributed-memory parallel computer.

NMR study of B-2p Fermi-level density of states in the transition metal diborides

NASA Astrophysics Data System (ADS)

Lue, C. S.; Lai, W. J.

2005-04-01

We present a systematic study of the AlB2-type transition metal diborides by measuring the 11B NMR spin-lattice relaxation rate on TiB2, VB2, ZrB2, NbB2, HfB2, as well as TaB2. For all studied materials, the observed relaxation at B nuclei is mainly due to the p-electrons. The comparison with theoretical calculations allows the experimental determination of the partial B-2p Fermi-level density of states (DOS). In addition, the extracted B-2p Fermi-level DOS values in TiB2, ZrB2, and HfB are consistently smaller than in VB2, NbB2, and TaB2. We connect this trend to the rigid-band scenario raised by band structure calculations.

New PPARγ partial agonist improves obesity-induced metabolic alterations and atherosclerosis in LDLr(-/-) mice.

PubMed

Silva, Jacqueline C; César, Fernanda A; de Oliveira, Edson M; Turato, Walter M; Tripodi, Gustavo L; Castilho, Gabriela; Machado-Lima, Adriana; de Las Heras, Beatriz; Boscá, Lisardo; Rabello, Marcelo M; Hernandes, Marcelo Z; Pitta, Marina G R; Pitta, Ivan R; Passarelli, Marisa; Rudnicki, Martina; Abdalla, Dulcineia S P

2016-02-01

Peroxisome proliferator-activated receptor gamma (PPARγ) regulates multiple pathways involved in the pathogenesis of obesity and atherosclerosis. Here, we evaluated the therapeutic potential of GQ-177, a new thiazolidinedione, on diet-induced obesity and atherosclerosis. The intermolecular interaction between PPARγ and GQ-177 was examined by virtual docking and PPAR activation was determined by reporter gene assay identifying GQ-177 as a partial and selective PPARγ agonist. For the evaluation of biological activity of GQ-177, low-density lipoprotein receptor-deficient (LDLr(-/-)) C57/BL6 mice were fed either a high fat diabetogenic diet (diet-induced obesity), or a high fat atherogenic diet, and treated with vehicle, GQ-177 (20mg/kg/day), pioglitazone (20mg/kg/day, diet-induced obesity model) or rosiglitazone (15mg/kg/day, atherosclerosis model) for 28 days. In diet-induced obesity mice, GQ-177 improved insulin sensitivity and lipid profile, increased plasma adiponectin and GLUT4 mRNA in adipose tissue, without affecting body weight, food consumption, fat accumulation and bone density. Moreover, GQ-177 enhanced hepatic mRNA levels of proteins involved in lipid metabolism. In the atherosclerosis mice, GQ-177 inhibited atherosclerotic lesion progression, increased plasma HDL and mRNA levels of PPARγ and ATP-binding cassette A1 in atherosclerotic lesions. GQ-177 acts as a partial PPARγ agonist that improves obesity-associated insulin resistance and dyslipidemia with atheroprotective effects in LDLr(-/-) mice. Copyright © 2015 Elsevier Ltd. All rights reserved.

Partial Cutting and Establishment of Artificial Nuttall Oak Regeneration in the Mississippi Alluvial Plain

Treesearch

Benjamin P. Ware; Emile S. Gardiner

2004-01-01

In the fall of 1998, we harvested a mixed bottomland hardwood stand in Sharkey County, MS, to establish two replicates of three residual stocking levels (0, 25, and 50 percent). We compared the various stand densities for suitability in establishment and growth of artificial oak regeneration. Following the overstory harvest, treatment plots received chain saw site...

Separability and Entanglement in the Hilbert Space Reference Frames Related Through the Generic Unitary Transform for Four Level System

NASA Astrophysics Data System (ADS)

Man'ko, V. I.; Markovich, L. A.

2018-02-01

Quantum correlations in the state of four-level atom are investigated by using generic unitary transforms of the classical (diagonal) density matrix. Partial cases of pure state, X-state, Werner state are studied in details. The geometrical meaning of unitary Hilbert reference-frame rotations generating entanglement in the initially separable state is discussed. Characteristics of the entanglement in terms of concurrence, entropy and negativity are obtained as functions of the unitary matrix rotating the reference frame.

Modeling the electrode-neuron interface of cochlear implants: effects of neural survival, electrode placement, and the partial tripolar configuration.

PubMed

Goldwyn, Joshua H; Bierer, Steven M; Bierer, Julie Arenberg

2010-09-01

The partial tripolar electrode configuration is a relatively novel stimulation strategy that can generate more spatially focused electric fields than the commonly used monopolar configuration. Focused stimulation strategies should improve spectral resolution in cochlear implant users, but may also be more sensitive to local irregularities in the electrode-neuron interface. In this study, we develop a practical computer model of cochlear implant stimulation that can simulate neural activation in a simplified cochlear geometry and we relate the resulting patterns of neural activity to basic psychophysical measures. We examine how two types of local irregularities in the electrode-neuron interface, variations in spiral ganglion nerve density and electrode position within the scala tympani, affect the simulated neural activation patterns and how these patterns change with electrode configuration. The model shows that higher partial tripolar fractions activate more spatially restricted populations of neurons at all current levels and require higher current levels to excite a given number of neurons. We find that threshold levels are more sensitive at high partial tripolar fractions to both types of irregularities, but these effects are not independent. In particular, at close electrode-neuron distances, activation is typically more spatially localized which leads to a greater influence of neural dead regions. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Partial melting of a Pb-Sn mushy layer due to heating from above, and implications for regional melting of Earth's directionally solidified inner core

NASA Astrophysics Data System (ADS)

Yu, James; Bergman, Michael I.; Huguet, Ludovic; Alboussiere, Thierry

2015-09-01

Superimposed on the radial solidification of Earth's inner core may be hemispherical and/or regional patches of melting at the inner-outer core boundary. Little work has been carried out on partial melting of a dendritic mushy layer due to heating from above. Here we study directional solidification, annealing, and partial melting from above of Pb-rich Sn alloy ingots. We find that partial melting from above results in convection in the mushy layer, with dense, melted Pb sinking and resolidifying at a lower height, yielding a different density profile than for those ingots that are just directionally solidified, irrespective of annealing. Partial melting from above causes a greater density deeper down and a corresponding steeper density decrease nearer the top. There is also a change in microstructure. These observations may be in accordance with inferences of east-west and perhaps smaller-scale variations in seismic properties near the top of the inner core.

Partial-reflection studies of D-region winter variability. [electron density measurements

NASA Technical Reports Server (NTRS)

Denny, B. W.; Bowhill, S. A.

1973-01-01

D-region electron densities were measured from December, 1972, to July, 1973, at Urbana, Illinois (latitude 40.2N) using the partial-reflection technique. During the winter, electron densities at altitudes of 72, 76.5, and 81 km show cyclical changes with a period of about 5 days that are highly correlated between these altitudes, suggesting that the mechanism responsible for the winter anomaly in D-region ionization applies throughout this height region. From January 13 to February 3, a pronounced wave-like variation occurred in the partial-reflection measurements, apparently associated with a major stratospheric warming that developed in that period. During the same time period, a traveling periodic variation is observed in the 10-mb height; it is highly correlated with the partial-reflection measurements. Electron density enhancements occur approximately at the same time as increases in the 10-mb height. Comparison of AL and A3 absorption measurements with electron density measurements below 82 km indicates that the winter anomaly in D-region ionization is divided into two types. Type 1, above about 82 km, extends horizontally for about 200 km while type 2, below about 82 km, extends for a horizontal scale of at least 1000 km.

Internal tidal currents in the Gaoping (Kaoping) Submarine Canyon

USGS Publications Warehouse

Lee, I.-H.; Wang, Y.-H.; Liu, J.T.; Chuang, W.-S.; Xu, Jie

2009-01-01

Data from five separate field experiments during 2000-2006 were used to study the internal tidal flow patterns in the Gaoping (formerly spelled Kaoping) Submarine Canyon. The internal tides are large with maximum interface displacements of about 200??m and maximum velocities of over 100cm/s. They are characterized by a first-mode velocity and density structure with zero crossing at about 100??m depth. In the lower layer, the currents increase with increasing depth. The density interface and the along-channel velocity are approximately 90?? out-of-phase, suggesting a predominant standing wave pattern. However, partial reflection is indicated as there is a consistent phase advance between sea level and density interface along the canyon axis. ?? 2008 Elsevier B.V. All rights reserved.

Application of a Modular Particle-Continuum Method to Partially Rarefied, Hypersonic Flow

NASA Astrophysics Data System (ADS)

Deschenes, Timothy R.; Boyd, Iain D.

2011-05-01

The Modular Particle-Continuum (MPC) method is used to simulate partially-rarefied, hypersonic flow over a sting-mounted planetary probe configuration. This hybrid method uses computational fluid dynamics (CFD) to solve the Navier-Stokes equations in regions that are continuum, while using direct simulation Monte Carlo (DSMC) in portions of the flow that are rarefied. The MPC method uses state-based coupling to pass information between the two flow solvers and decouples both time-step and mesh densities required by each solver. It is parallelized for distributed memory systems using dynamic domain decomposition and internal energy modes can be consistently modeled to be out of equilibrium with the translational mode in both solvers. The MPC results are compared to both full DSMC and CFD predictions and available experimental measurements. By using DSMC in only regions where the flow is nonequilibrium, the MPC method is able to reproduce full DSMC results down to the level of velocity and rotational energy probability density functions while requiring a fraction of the computational time.

Adrenocortical responses in Japanese quail classified by their permanence in proximity to either low or high density of conspecifics.

PubMed

Guzmán, D A; Lèche, A; Contarde, C B; Nazar, F N; Marin, R H

2018-06-19

The density-related permanence test (DRP) is used to classify young birds (while in groups) according to their individual permanence in proximity to either a high or low density of conspecifics (HD or LD, respectively). The birds' performance in DRP was associated with underlying differences in the social responses of their individuals. Quails in homogeneous groups of LD residents responded with less compact groups and higher levels of agonistic interactions to the presence of an intruder, and showed higher levels of agonistic interactions among cagemates than the homogeneous groups of HD birds. This study deepen the characterization of DRP evaluating whether contrasting behavior during test is associated with birds' stress responses to challenging situations during rearing. Plasma corticosterone responses were individually assessed after submitting DRP categorized birds to a brief (10 min) partial restraint (mechanical stressor; experiment 1), or after introducing them during 5 min as intruders in homogeneous groups of 6 unknown same category (HD or LD) conspecifics (social stressor; experiment 2). Experiment 1 showed that basal corticosterone levels were similar in all groups and the partial mechanical restraint induced an increase in plasma corticosterone concentration also in all groups. However, the increase induced by the stressor was higher in the LD birds than in their HD counterparts. In experiment 2, compared to controls, social stressor showed no plasma corticosterone changes in the intruders that were introduced in an unfamiliar group of HD conspecifics. However, intruders (both HD and LD) that were visiting the LD residents showed an increased corticosterone response compared to their control counterparts. Results suggest that categorization of birds in the DRP test could have relevance for selection programs oriented to obtain birds better suited to intensive rearing conditions that includes high density of animals and exposure to unavoidable stressors.

On Steady-State Tropical Cyclones

DTIC Science & Technology

2014-01-01

components of the velocity vector, specific humidity, suspended liquid water, perturbation Exner function and perturbation density potential...vorticity and spin-up function, respectively. If the flow is symmetrically stable, the partial differential equation (10) is elliptic with a forcing term...Upper-level inflow jets A prominent feature of the radial velocity component shown in Figure 2(c) is the layered structure of inflow and outflow in the

Investigation of electronic structure and chemical bonding of intermetallic Pd2HfIn: An ab-initio study

NASA Astrophysics Data System (ADS)

Bano, Amreen; Gaur, N. K.

2018-05-01

Ab-initio calculations are carried out to study the electronic and chemical bonding properties of Intermetallic full Heusler compound Pd2HfIn which crystallizes in F-43m structure. All calculations are performed by using density functional theory (DFT) based code Quantum Espresso. Generalized gradient approximations (GGA) of Perdew- Burke- Ernzerhof (PBE) have been adopted for exchange-correlation potential. Calculated electronic band structure reveals the metallic character of the compound. From partial density of states (PDoS), we found the presence of relatively high intensity electronic states of 4d-Pd atom at Fermi level. We have found a pseudo-gap just abouve the Fermi level and N(E) at Fermi level is observed to be 0.8 states/eV, these finding indicates the existence of superconducting character in Pd2HfIn.

Complete wavelength mismatching effect in a Doppler broadened Y-type six-level EIT atomic medium

NASA Astrophysics Data System (ADS)

Bharti, Vineet; Wasan, Ajay

We present a theoretical study of the Doppler broadened Y-type six-level atomic system, using a density matrix approach, to investigate the effect of varying control field wavelengths and closely spaced hyperfine levels in the 5P state of 87Rb. The closely spaced hyperfine levels in our six-level system affect the optical properties of Y-type system and cause asymmetry in absorption profiles. Depending upon the choices of π-probe, σ+-control and σ--control fields transitions, we consider three regimes: (i) perfect wavelength matching regime (λp=λ=λ), (ii) partial wavelength mismatching regime (λp≠λ=λ), and (iii) complete wavelength mismatching regime (λp≠λ≠λ). The complete wavelength mismatching regime is further distinguished into two situations, i.e., λ<λ and λ>λ. We have shown that in the room temperature atomic vapor, the asymmetric transparency window gets broadened in the partial wavelength mismatching regime as compared to the perfect wavelength matching regime. This broad transparency window also splits at the line center in the complete wavelength mismatching regime.

Voltage dependent potassium channel remodeling in murine intestinal smooth muscle hypertrophy induced by partial obstruction.

PubMed

Liu, Dong-Hai; Huang, Xu; Guo, Xin; Meng, Xiang-Min; Wu, Yi-Song; Lu, Hong-Li; Zhang, Chun-Mei; Kim, Young-chul; Xu, Wen-Xie

2014-01-01

Partial obstruction of the small intestine causes obvious hypertrophy of smooth muscle cells and motility disorder in the bowel proximate to the obstruction. To identify electric remodeling of hypertrophic smooth muscles in partially obstructed murine small intestine, the patch-clamp and intracellular microelectrode recording methods were used to identify the possible electric remodeling and Western blot, immunofluorescence and immunoprecipitation were utilized to examine the channel protein expression and phosphorylation level changes in this research. After 14 days of obstruction, partial obstruction caused obvious smooth muscle hypertrophy in the proximally located intestine. The slow waves of intestinal smooth muscles in the dilated region were significantly suppressed, their amplitude and frequency were reduced, whilst the resting membrane potentials were depolarized compared with normal and sham animals. The current density of voltage dependent potassium channel (KV) was significantly decreased in the hypertrophic smooth muscle cells and the voltage sensitivity of KV activation was altered. The sensitivity of KV currents (IKV) to TEA, a nonselective potassium channel blocker, increased significantly, but the sensitivity of IKv to 4-AP, a KV blocker, stays the same. The protein levels of KV4.3 and KV2.2 were up-regulated in the hypertrophic smooth muscle cell membrane. The serine and threonine phosphorylation levels of KV4.3 and KV2.2 were significantly increased in the hypertrophic smooth muscle cells. Thus this study represents the first identification of KV channel remodeling in murine small intestinal smooth muscle hypertrophy induced by partial obstruction. The enhanced phosphorylations of KV4.3 and KV2.2 may be involved in this process.

A Numeric Analysis of Bone Density in the Edentulous Interforaminal Region.

PubMed

Tavitian, Patrick; Ruquet, Michel; Mensé, Chloe; Nicolas, Emmanuel; Hue, Olivier

The purpose of this study was to assess the density of interforaminal bone using quantitative computed tomography (QCT) in simulated case histories to be prescribed an All-on-Five fixed implant treatment protocol. QCT scans from 30 edentulous patients (15 men and 15 women; mean age 63.33 ± 9.3 years) were analyzed using the Nobel Clinician software. Densities (in Hounsfield units [HU]) were recorded at the neck, middle part of the body, and apex of the lingual and buccal parts of proposed implant sites. The highest bone densities were measured at the neck of the implant (1,187 ± 382 HU), with lower densities at the apex (774 ± 571 HU) (P < .01). Bone densities decreased on the lingual interforaminal portion of the implant, especially on the two intermediate implants. Bone density was lower in women (917 ± 510 HU) than in men (1,095 ± 601 HU) (P < .01). The interforaminal measured bone densities are lower on the paramedian region of the symphysis and in women. However, these levels are in accordance with immediate loading with a fixed partial denture.

Melt segregation from partially molten source regions - The importance of melt density and source region size

NASA Technical Reports Server (NTRS)

Stolper, E.; Hager, B. H.; Walker, D.; Hays, J. F.

1981-01-01

An investigation is conducted regarding the changes expected in the density contrast between basic melts and peridotites with increasing pressure using the limited data available on the compressibilities of silicate melts and data on the densities of mantle minerals. It is concluded that since compressibilities of silicate melts are about an order of magnitude greater than those of mantle minerals, the density contrast between basic melts and mantle minerals must diminish significantly with increasing pressure. An earlier analysis regarding the migration of liquid in partially molten source regions conducted by Walker et al. (1978) is extended, giving particular attention to the influence of the diminished density contrast between melt and residual crystals with increasing source region depth and to the influence of source region size. This analysis leads to several generalizations concerning the factors influencing the depths at which magmas will segregate from their source regions and the degrees of partial melting that can be achieved in these source regions before melt segregation occurs.

Spatial Distribution of Oxygen Chemical Potential under Potential Gradients and Theoretical Maximum Power Density with 8YSZ Electrolyte

NASA Astrophysics Data System (ADS)

Lim, Dae-Kwang; Im, Ha-Ni; Song, Sun-Ju

2016-01-01

The maximum power density of SOFC with 8YSZ electrolyte as the function of thickness was calculated by integrating partial conductivities of charge carriers under various DC bias conditions at a fixed oxygen chemical potential gradient at both sides of the electrolyte. The partial conductivities were successfully taken using the Hebb-Wagner polarization method as a function of temperature and oxygen partial pressure, and the spatial distribution of oxygen partial pressure across the electrolyte was calculated based on Choudhury and Patterson’s model by considering zero electrode polarization. At positive voltage conditions corresponding to SOFC and SOEC, the high conductivity region was expanded, but at negative cell voltage condition, the low conductivity region near n-type to p-type transition was expanded. In addition, the maximum power density calculated from the current-voltage characteristic showed approximately 5.76 W/cm2 at 700 oC with 10 μm thick-8YSZ, while the oxygen partial pressure of the cathode and anode sides maintained ≈0.21 and 10-22 atm.

Ameliorative role of gemfibrozil against partial abdominal aortic constriction-induced cardiac hypertrophy in rats.

PubMed

Singh, Amrit Pal; Singh, Randhir; Krishan, Pawan

2015-04-01

Fibrates are peroxisome proliferator-activated receptor-α agonists and are clinically used for treatment of dyslipidemia and hypertriglyceridemia. Fenofibrate is reported as a cardioprotective agent in various models of cardiac dysfunction; however, limited literature is available regarding the role of gemfibrozil as a possible cardioprotective agent, especially in a non-obese model of cardiac remodelling. The present study investigated the role of gemfibrozil against partial abdominal aortic constriction-induced cardiac hypertrophy in rats. Cardiac hypertrophy was induced by partial abdominal aortic constriction in rats and they survived for 4 weeks. The cardiac hypertrophy was assessed by measuring left ventricular weight to body weight ratio, left ventricular wall thickness, and protein and collagen content. The oxidative stress in the cardiac tissues was assessed by measuring thiobarbituric acid-reactive substances, superoxide anion generation, and reduced glutathione level. The haematoxylin-eosin and picrosirius red staining was used to observe cardiomyocyte diameter and collagen deposition, respectively. Moreover, serum levels of cholesterol, high-density lipoproteins, triglycerides, and glucose were also measured. Gemfibrozil (30 mg/kg, p.o.) was administered since the first day of partial abdominal aortic constriction and continued for 4 weeks. The partial abdominal aortic constriction-induced cardiac oxidative stress and hypertrophy are indicated by significant change in various parameters used in the present study that were ameliorated with gemfibrozil treatment in rats. No significant change in serum parameters was observed between various groups used in the present study. It is concluded that gemfibrozil ameliorates partial abdominal aortic constriction-induced cardiac oxidative stress and hypertrophy and in rats.

Contribution of 20 single nucleotide polymorphisms of 13 genes to dyslipidemia associated with antiretroviral therapy.

PubMed

Arnedo, Mireia; Taffé, Patrick; Sahli, Roland; Furrer, Hansjakob; Hirschel, Bernard; Elzi, Luigia; Weber, Rainer; Vernazza, Pietro; Bernasconi, Enos; Darioli, Roger; Bergmann, Sven; Beckmann, Jacques S; Telenti, Amalio; Tarr, Philip E

2007-09-01

HIV-1 infected individuals have an increased cardiovascular risk which is partially mediated by dyslipidemia. Single nucleotide polymorphisms in multiple genes involved in lipid transport and metabolism are presumed to modulate the risk of dyslipidemia in response to antiretroviral therapy. The contribution to dyslipidemia of 20 selected single nucleotide polymorphisms of 13 genes reported in the literature to be associated with plasma lipid levels (ABCA1, ADRB2, APOA5, APOC3, APOE, CETP, LIPC, LIPG, LPL, MDR1, MTP, SCARB1, and TNF) was assessed by longitudinally modeling more than 4400 plasma lipid determinations in 438 antiretroviral therapy-treated participants during a median period of 4.8 years. An exploratory genetic score was tested that takes into account the cumulative contribution of multiple gene variants to plasma lipids. Variants of ABCA1, APOA5, APOC3, APOE, and CETP contributed to plasma triglyceride levels, particularly in the setting of ritonavir-containing antiretroviral therapy. Variants of APOA5 and CETP contributed to high-density lipoprotein-cholesterol levels. Variants of CETP and LIPG contributed to non-high-density lipoprotein-cholesterol levels, a finding not reported previously. Sustained hypertriglyceridemia and low high-density lipoprotein-cholesterol during the study period was significantly associated with the genetic score. Single nucleotide polymorphisms of ABCA1, APOA5, APOC3, APOE, and CETP contribute to plasma triglyceride and high-density lipoprotein-cholesterol levels during antiretroviral therapy exposure. Genetic profiling may contribute to the identification of patients at risk for antiretroviral therapy-related dyslipidemia.

3-D density imaging with muon flux measurements from underground galleries

NASA Astrophysics Data System (ADS)

Lesparre, N.; Cabrera, J.; Marteau, J.

2017-03-01

Atmospheric muon flux measurements provide information on subsurface density distribution. In this study, muon flux was measured underground, in the Tournemire experimental platform (France). The objective was to image the medium between the galleries and the surface and evaluate the feasibility to detect the presence of discontinuities, for example, produced by secondary subvertical faults or by karstic networks. Measurements were performed from three different sites with a partial overlap of muon trajectories, offering the possibility to seek density variations at different depths. The conversion of the measured muon flux to average density values showed global variations further analysed through a 3-D nonlinear inversion procedure. Main results are the presence of a very low density region at the level of the upper aquifer, compatible with the presence of a karstic network hosting local cavities, and the absence of secondary faults. We discuss the validity of the present results and propose different strategies to improve the accuracy of such measurements and analysis.

Effect of Landscape Pattern on Insect Species Density within Urban Green Spaces in Beijing, China

PubMed Central

Su, Zhimin; Li, Xiaoma; Zhou, Weiqi; Ouyang, Zhiyun

2015-01-01

Urban green space is an important refuge of biodiversity in urban areas. Therefore, it is crucial to understand the relationship between the landscape pattern of green spaces and biodiversity to mitigate the negative effects of urbanization. In this study, we collected insects from 45 green patches in Beijing during July 2012 using suction sampling. The green patches were dominated by managed lawns, mixed with scattered trees and shrubs. We examined the effects of landscape pattern on insect species density using hierarchical partitioning analysis and partial least squares regression. The results of the hierarchical partitioning analysis indicated that five explanatory variables, i.e., patch area (with 19.9% independent effects), connectivity (13.9%), distance to nearest patch (13.8%), diversity for patch types (11.0%), and patch shape (8.3%), significantly contributed to insect species density. With the partial least squares regression model, we found species density was negatively related to patch area, shape, connectivity, diversity for patch types and proportion of impervious surface at the significance level of p < 0.05 and positively related to proportion of vegetated land. Regression tree analysis further showed that the highest species density was found in green patches with an area <500 m2. Our results indicated that improvement in habitat quality, such as patch area and connectivity that are typically thought to be important for conservation, did not actually increase species density. However, increasing compactness (low-edge) of patch shape and landscape composition did have the expected effect. Therefore, it is recommended that the composition of the surrounding landscape should be considered simultaneously with planned improvements in local habitat quality. PMID:25793897

Effect of landscape pattern on insect species density within urban green spaces in Beijing, China.

PubMed

Su, Zhimin; Li, Xiaoma; Zhou, Weiqi; Ouyang, Zhiyun

2015-01-01

Urban green space is an important refuge of biodiversity in urban areas. Therefore, it is crucial to understand the relationship between the landscape pattern of green spaces and biodiversity to mitigate the negative effects of urbanization. In this study, we collected insects from 45 green patches in Beijing during July 2012 using suction sampling. The green patches were dominated by managed lawns, mixed with scattered trees and shrubs. We examined the effects of landscape pattern on insect species density using hierarchical partitioning analysis and partial least squares regression. The results of the hierarchical partitioning analysis indicated that five explanatory variables, i.e., patch area (with 19.9% independent effects), connectivity (13.9%), distance to nearest patch (13.8%), diversity for patch types (11.0%), and patch shape (8.3%), significantly contributed to insect species density. With the partial least squares regression model, we found species density was negatively related to patch area, shape, connectivity, diversity for patch types and proportion of impervious surface at the significance level of p < 0.05 and positively related to proportion of vegetated land. Regression tree analysis further showed that the highest species density was found in green patches with an area <500 m2. Our results indicated that improvement in habitat quality, such as patch area and connectivity that are typically thought to be important for conservation, did not actually increase species density. However, increasing compactness (low-edge) of patch shape and landscape composition did have the expected effect. Therefore, it is recommended that the composition of the surrounding landscape should be considered simultaneously with planned improvements in local habitat quality.

Optimization of magnetic flux density measurement using multiple RF receiver coils and multi-echo in MREIT.

PubMed

Jeong, Woo Chul; Chauhan, Munish; Sajib, Saurav Z K; Kim, Hyung Joong; Serša, Igor; Kwon, Oh In; Woo, Eung Je

2014-09-07

Magnetic Resonance Electrical Impedance Tomography (MREIT) is an MRI method that enables mapping of internal conductivity and/or current density via measurements of magnetic flux density signals. The MREIT measures only the z-component of the induced magnetic flux density B = (Bx, By, Bz) by external current injection. The measured noise of Bz complicates recovery of magnetic flux density maps, resulting in lower quality conductivity and current-density maps. We present a new method for more accurate measurement of the spatial gradient of the magnetic flux density gradient (∇ Bz). The method relies on the use of multiple radio-frequency receiver coils and an interleaved multi-echo pulse sequence that acquires multiple sampling points within each repetition time. The noise level of the measured magnetic flux density Bz depends on the decay rate of the signal magnitude, the injection current duration, and the coil sensitivity map. The proposed method uses three key steps. The first step is to determine a representative magnetic flux density gradient from multiple receiver coils by using a weighted combination and by denoising the measured noisy data. The second step is to optimize the magnetic flux density gradient by using multi-echo magnetic flux densities at each pixel in order to reduce the noise level of ∇ Bz and the third step is to remove a random noise component from the recovered ∇ Bz by solving an elliptic partial differential equation in a region of interest. Numerical simulation experiments using a cylindrical phantom model with included regions of low MRI signal to noise ('defects') verified the proposed method. Experimental results using a real phantom experiment, that included three different kinds of anomalies, demonstrated that the proposed method reduced the noise level of the measured magnetic flux density. The quality of the recovered conductivity maps using denoised ∇ Bz data showed that the proposed method reduced the conductivity noise level up to 3-4 times at each anomaly region in comparison to the conventional method.

Mammographic density estimation with automated volumetric breast density measurement.

PubMed

Ko, Su Yeon; Kim, Eun-Kyung; Kim, Min Jung; Moon, Hee Jung

2014-01-01

To compare automated volumetric breast density measurement (VBDM) with radiologists' evaluations based on the Breast Imaging Reporting and Data System (BI-RADS), and to identify the factors associated with technical failure of VBDM. In this study, 1129 women aged 19-82 years who underwent mammography from December 2011 to January 2012 were included. Breast density evaluations by radiologists based on BI-RADS and by VBDM (Volpara Version 1.5.1) were compared. The agreement in interpreting breast density between radiologists and VBDM was determined based on four density grades (D1, D2, D3, and D4) and a binary classification of fatty (D1-2) vs. dense (D3-4) breast using kappa statistics. The association between technical failure of VBDM and patient age, total breast volume, fibroglandular tissue volume, history of partial mastectomy, the frequency of mass > 3 cm, and breast density was analyzed. The agreement between breast density evaluations by radiologists and VBDM was fair (k value = 0.26) when the four density grades (D1/D2/D3/D4) were used and moderate (k value = 0.47) for the binary classification (D1-2/D3-4). Twenty-seven women (2.4%) showed failure of VBDM. Small total breast volume, history of partial mastectomy, and high breast density were significantly associated with technical failure of VBDM (p = 0.001 to 0.015). There is fair or moderate agreement in breast density evaluation between radiologists and VBDM. Technical failure of VBDM may be related to small total breast volume, a history of partial mastectomy, and high breast density.

Densities of L-Glutamic Acid HCl Drug in Aqueous NaCl and KCl Solutions at Different Temperatures

NASA Astrophysics Data System (ADS)

Ryshetti, Suresh; Raghuram, Noothi; Rani, Emmadi Jayanthi; Tangeda, Savitha Jyostna

2016-04-01

Densities (ρ ) of (0.01 to 0.07) {mol}{\\cdot } {kg}^{-1} L-Glutamic acid HCl (L-HCl) drug in water, and in aqueous NaCl and KCl (0.5 and 1.0) {mol}{\\cdot } {kg}^{-1} solutions have been reported as a function of temperature at T = (298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure. The accurate density (ρ ) values are used to estimate the various parameters such as the apparent molar volume (V_{2,{\\upphi }}), the partial molar volume (V2^{∞}), the isobaric thermal expansion coefficient (α 2), the partial molar expansion (E2^{∞}), and Hepler's constant (partial 2V2^{∞}/partial T2)P. The Cosphere overlap model is used to understand the solute-solvent interactions in a ternary mixture (L-HCl drug + NaCl or KCl + water). Hepler's constant (partial 2V2^{∞}/partial T2)_P is utilized to interpret the structure-making or -breaking ability of L-HCl drug in aqueous NaCl and KCl solutions, and the results are inferred that L-HCl drug acts as a structure maker, i.e., kosmotrope in aqueous NaCl solutions and performs as a structure breaker, i.e., chaotrope in aqueous KCl solutions.

Association of macrophage inhibitory cytokine-1 with nutritional status, body composition and bone mineral density in patients with anorexia nervosa: the influence of partial realimentation.

PubMed

Dostálová, Ivana; Kaválková, Petra; Papežová, Hana; Domluvilová, Daniela; Zikán, Vít; Haluzík, Martin

2010-04-23

Macrophage inhibitory cytokine-1 (MIC-1) is a key inducer of cancer-related anorexia and weight loss. However, its possible role in the etiopathogenesis of nutritional disorders of other etiology such as anorexia nervosa (AN) is currently unknown. We measured fasting serum concentrations of MIC-1 in patients with AN before and after 2-month nutritional treatment and explored its relationship with nutritional status, metabolic and biochemical parameters. Sixteen previously untreated women with AN and twenty-five normal-weight age-matched control women participated in the study. We measured serum concentrations of MIC-1 and leptin by ELISA, free fatty acids by enzymatic colorimetric assay, and biochemical parameters by standard laboratory methods; determined resting energy expenditure by indirect calorimetry; and assessed bone mineral density and body fat content by dual-energy X-ray absorptiometry. ANOVA, unpaired t-test or Mann-Whitney test were used for groups comparison as appropriate. The comparisons of serum MIC-1 levels and other studied parameters in patients with AN before and after partial realimentation were assessed by paired t-test or Wilcoxon Signed Rank Test as appropriate. At baseline, fasting serum MIC-1 concentrations were significantly higher in patients with AN relative to controls. Partial realimentation significantly reduced serum MIC-1 concentrations in patients with AN but it still remained significantly higher compared to control group. In AN group, serum MIC-1 was inversely related to Buzby nutritional risk index, serum insulin-like growth factor-1, serum glucose, serum total protein, serum albumin, and lumbar bone mineral density and it significantly positively correlated with the duration of AN and age. MIC-1 concentrations in AN patients are significantly higher relative to healthy women. Partial realimentation significantly decreased MIC-1 concentration in AN group. Clinical significance of these findings needs to be further clarified.

Density perturbations in general modified gravitational theories

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

De Felice, Antonio; Tsujikawa, Shinji; Mukohyama, Shinji

2010-07-15

We derive the equations of linear cosmological perturbations for the general Lagrangian density f(R,{phi},X)/2+L{sub c}, where R is a Ricci scalar, {phi} is a scalar field, and X=-{partial_derivative}{sup {mu}{phi}{partial_derivative}}{sub {mu}{phi}/}2 is a field kinetic energy. We take into account a nonlinear self-interaction term L{sub c}={xi}({phi}) {open_square}{phi}({partial_derivative}{sup {mu}{phi}{partial_derivative}}{sub {mu}{phi}}) recently studied in the context of ''Galileon'' cosmology, which keeps the field equations at second order. Taking into account a scalar-field mass explicitly, the equations of matter density perturbations and gravitational potentials are obtained under a quasistatic approximation on subhorizon scales. We also derive conditions for the avoidance of ghosts and Laplacianmore » instabilities associated with propagation speeds. Our analysis includes most of modified gravity models of dark energy proposed in literature; and thus it is convenient to test the viability of such models from both theoretical and observational points of view.« less

Ion distributions, exclusion coefficients, and separation factors of electrolytes in a charged cylindrical nanopore: a partially perturbative density functional theory study.

PubMed

Peng, Bo; Yu, Yang-Xin

2009-10-07

The structural and thermodynamic properties for charge symmetric and asymmetric electrolytes as well as mixed electrolyte system inside a charged cylindrical nanopore are investigated using a partially perturbative density functional theory. The electrolytes are treated in the restricted primitive model and the internal surface of the cylindrical nanopore is considered to have a uniform charge density. The proposed theory is directly applicable to the arbitrary mixed electrolyte solution containing ions with the equal diameter and different valences. Large amount of simulation data for ion density distributions, separation factors, and exclusion coefficients are used to determine the range of validity of the partially perturbative density functional theory for monovalent and multivalent counterion systems. The proposed theory is found to be in good agreement with the simulations for both mono- and multivalent counterion systems. In contrast, the classical Poisson-Boltzmann equation only provides reasonable descriptions of monovalent counterion system at low bulk density, and is qualitatively and quantitatively wrong in the prediction for the multivalent counterion systems due to its neglect of the strong interionic correlations in these systems. The proposed density functional theory has also been applied to an electrolyte absorbed into a pore that is a model of the filter of a physiological calcium channel.

Synchronization versus decoherence of neutrino oscillations at intermediate densities

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

Raffelt, Georg G.; Tamborra, Irene

2010-12-15

We study collective oscillations of a two-flavor neutrino system with arbitrary but fixed density. In the vacuum limit, modes with different energies quickly dephase (kinematical decoherence), whereas in the limit of infinite density they lock to each other (synchronization). For intermediate densities, we find different classes of solutions. There is always a phase transition in the sense of partial synchronization occurring only above a density threshold. For small mixing angles, partial or complete decoherence can be induced by a parametric resonance, introducing a new time scale to the problem, the final outcome depending on the spectrum and mixing angle. Wemore » derive an analytic relation that allows us to calculate the late-time degree of coherence based on the spectrum alone.« less

Nonideal detonation regimes in low density explosives

NASA Astrophysics Data System (ADS)

Ershov, A. P.; Kashkarov, A. O.; Pruuel, E. R.; Satonkina, N. P.; Sil'vestrov, V. V.; Yunoshev, A. S.; Plastinin, A. V.

2016-02-01

Measurements using Velocity Interferometer System for Any Reflector (VISAR) were performed for three high explosives at densities slightly above the natural loose-packed densities. The velocity histories at the explosive/window interface demonstrate that the grain size of the explosives plays an important role. Fine-grained materials produced rather smooth records with reduced von Neumann spike amplitudes. For commercial coarse-grained specimens, the chemical spike (if detectable) was more pronounced. This difference can be explained as a manifestation of partial burn up. In fine-grained explosives, which are more sensitive, the reaction can proceed partly within the compression front, which leads to a lower initial shock amplitude. The reaction zone was shorter in fine-grained materials because of higher density of hot spots. The noise level was generally higher for the coarse-grained explosives, which is a natural stochastic effect of the highly non-uniform flow of the heterogeneous medium. These results correlate with our previous data of electrical conductivity diagnostics. Instead of the classical Zel'dovich-von Neumann-Döring profiles, violent oscillations around the Chapman-Jouguet level were observed in about half of the shots using coarse-grained materials. We suggest that these unusual records may point to a different detonation wave propagation mechanism.

Density profiles around A+B→C reaction-diffusion fronts in partially miscible systems: A general classification.

PubMed

Loodts, V; Trevelyan, P M J; Rongy, L; De Wit, A

2016-10-01

Various spatial density profiles can develop in partially miscible stratifications when a phase A dissolves with a finite solubility into a host phase containing a dissolved reactant B. We investigate theoretically the impact of an A+B→C reaction on such density profiles in the host phase and classify them in a parameter space spanned by the ratios of relative contributions to density and diffusion coefficients of the chemical species. While the density profile is either monotonically increasing or decreasing in the nonreactive case, reactions combined with differential diffusivity can create eight different types of density profiles featuring up to two extrema in density, at the reaction front or below it. We use this framework to predict various possible hydrodynamic instability scenarios inducing buoyancy-driven convection around such reaction fronts when they propagate parallel to the gravity field.

A moving mesh finite difference method for equilibrium radiation diffusion equations

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

Yang, Xiaobo, E-mail: xwindyb@126.com; Huang, Weizhang, E-mail: whuang@ku.edu; Qiu, Jianxian, E-mail: jxqiu@xmu.edu.cn

2015-10-01

An efficient moving mesh finite difference method is developed for the numerical solution of equilibrium radiation diffusion equations in two dimensions. The method is based on the moving mesh partial differential equation approach and moves the mesh continuously in time using a system of meshing partial differential equations. The mesh adaptation is controlled through a Hessian-based monitor function and the so-called equidistribution and alignment principles. Several challenging issues in the numerical solution are addressed. Particularly, the radiation diffusion coefficient depends on the energy density highly nonlinearly. This nonlinearity is treated using a predictor–corrector and lagged diffusion strategy. Moreover, the nonnegativitymore » of the energy density is maintained using a cutoff method which has been known in literature to retain the accuracy and convergence order of finite difference approximation for parabolic equations. Numerical examples with multi-material, multiple spot concentration situations are presented. Numerical results show that the method works well for radiation diffusion equations and can produce numerical solutions of good accuracy. It is also shown that a two-level mesh movement strategy can significantly improve the efficiency of the computation.« less

The density and distribution of Sitka spruce and western hemlock seedling banks in partially harvested stands in southeast Alaska

Treesearch

Louise S.Y. Levy; Robert L. Deal; John C. Tappeiner

2010-01-01

This study’s objective was to document and describe the current seedling bank of Sitka spruce (Picea sitchensis (Bong.) Carr.) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) stands in southeast Alaska that were partially cut between 1900 and 1984. We investigated the following: (1) What are seedling bank densities? (2)...

Mammographic Density Estimation with Automated Volumetric Breast Density Measurement

PubMed Central

Ko, Su Yeon; Kim, Eun-Kyung; Kim, Min Jung

2014-01-01

Objective To compare automated volumetric breast density measurement (VBDM) with radiologists' evaluations based on the Breast Imaging Reporting and Data System (BI-RADS), and to identify the factors associated with technical failure of VBDM. Materials and Methods In this study, 1129 women aged 19-82 years who underwent mammography from December 2011 to January 2012 were included. Breast density evaluations by radiologists based on BI-RADS and by VBDM (Volpara Version 1.5.1) were compared. The agreement in interpreting breast density between radiologists and VBDM was determined based on four density grades (D1, D2, D3, and D4) and a binary classification of fatty (D1-2) vs. dense (D3-4) breast using kappa statistics. The association between technical failure of VBDM and patient age, total breast volume, fibroglandular tissue volume, history of partial mastectomy, the frequency of mass > 3 cm, and breast density was analyzed. Results The agreement between breast density evaluations by radiologists and VBDM was fair (k value = 0.26) when the four density grades (D1/D2/D3/D4) were used and moderate (k value = 0.47) for the binary classification (D1-2/D3-4). Twenty-seven women (2.4%) showed failure of VBDM. Small total breast volume, history of partial mastectomy, and high breast density were significantly associated with technical failure of VBDM (p = 0.001 to 0.015). Conclusion There is fair or moderate agreement in breast density evaluation between radiologists and VBDM. Technical failure of VBDM may be related to small total breast volume, a history of partial mastectomy, and high breast density. PMID:24843235

Two-parameter partially correlated ground-state electron density of some light spherical atoms from Hartree-Fock theory with nonintegral nuclear charge

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

Cordero, Nicolas A.; March, Norman H.; Alonso, Julio A.

2007-05-15

Partially correlated ground-state electron densities for some spherical light atoms are calculated, into which nonrelativistic ionization potentials represent essential input data. The nuclear cusp condition of Kato is satisfied precisely. The basic theoretical starting point, however, is Hartree-Fock (HF) theory for the N electrons under consideration but with nonintegral nuclear charge Z{sup '} slightly different from the atomic number Z (=N). This HF density is scaled with a parameter {lambda}, near to unity, to preserve normalization. Finally, some tests are performed on the densities for the atoms Ne and Ar, as well as for Be and Mg.

Analyzing the dependence of oxygen incorporation current density on overpotential and oxygen partial pressure in mixed conducting oxide electrodes.

PubMed

Guan, Zixuan; Chen, Di; Chueh, William C

2017-08-30

The oxygen incorporation reaction, which involves the transformation of an oxygen gas molecule to two lattice oxygen ions in a mixed ionic and electronic conducting solid, is a ubiquitous and fundamental reaction in solid-state electrochemistry. To understand the reaction pathway and to identify the rate-determining step, near-equilibrium measurements have been employed to quantify the exchange coefficients as a function of oxygen partial pressure and temperature. However, because the exchange coefficient contains contributions from both forward and reverse reaction rate constants and depends on both oxygen partial pressure and oxygen fugacity in the solid, unique and definitive mechanistic assessment has been challenging. In this work, we derive a current density equation as a function of both oxygen partial pressure and overpotential, and consider both near and far from equilibrium limits. Rather than considering specific reaction pathways, we generalize the multi-step oxygen incorporation reaction into the rate-determining step, preceding and following quasi-equilibrium steps, and consider the number of oxygen ions and electrons involved in each. By evaluating the dependence of current density on oxygen partial pressure and overpotential separately, one obtains the reaction orders for oxygen gas molecules and for solid-state species in the electrode. We simulated the oxygen incorporation current density-overpotential curves for praseodymium-doped ceria for various candidate rate-determining steps. This work highlights a promising method for studying the exchange kinetics far away from equilibrium.

Density and viscosity of some partially carbonated aqueous alkanolamine solutions and their blends

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

Weiland, R.H.; Dingman, J.C.; Cronin, D.B.

1998-05-01

Very little information is available concerning the effect of acid gas loading on the physical properties of amine-treating solutions flowing through the absorption and regeneration columns used in gas processing. The densities and viscosities of partially carbonated monoethanolamine (MEA), diethanolamine (DEA), and N-methyldiethanolamine (MDEA) solutions were measured at 298 K. With increasing carbon dioxide loadings, significant increases in both density and viscosity were observed. These results were combined with literature data to produce correlations for alkanolamine solution density and viscosity as a function of amine concentration, carbon dioxide loading, and temperature. The resulting single-amine correlations were used to predict themore » densities and viscosities of DEA + MDEA and MEA + MDEA blends. Predictions are compared with data measured for these blends.« less

Serum lipoprotein (a) concentration in patients with nephrotic syndrome and its clinical implication.

PubMed

Yang, X; Wang, H; Zhu, Z; Deng, A

1998-01-01

Serum lipoprotein(a) [Lp(a)] concentration was determined in 42 patients with primary nephrotic syndrome (NS) and the relationships between Lp (a) and plasma lipids, apolipoproteins, serum creatinine (Scr), albumin, urinary proteins (Upro) were also analyzed. The results showed that: (1) serum Lp(a) concentrations in the patients with NS were higher than those in healthy controls; (2) the levels of serum Lp(a) were correlated positively with total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C), apolipoprotein B (Apo-B), Upros (Upro). It is concluded that the NS patients had the potential risk of suffering from coronary artery disease, glomerular sclerosis and thrombosis. The remission of NS may partially decrease the serum Lp(a) levels. Further studies are needed to explore the prevention and treatment of dislipedemia in patients with NS.

Representation of radiative strength functions within a practical model of cascade gamma decay

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

Vu, D. C., E-mail: vuconghnue@gmail.com; Sukhovoj, A. M., E-mail: suchovoj@nf.jinr.ru; Mitsyna, L. V., E-mail: mitsyna@nf.jinr.ru

A practical model developed at the Joint Institute for Nuclear Research (JINR, Dubna) in order to describe the cascade gamma decay of neutron resonances makes it possible to determine simultaneously, from an approximation of the intensities of two-step cascades, parameters of nuclear level densities and partial widths with respect to the emission of nuclear-reaction products. The number of the phenomenological ideas used isminimized in themodel version considered in the present study. An analysis of new results confirms what was obtained earlier for the dependence of dynamics of the interaction of fermion and boson nuclear states on the nuclear shape. Frommore » the ratio of the level densities for excitations of the vibrational and quasiparticle types, it also follows that this interaction manifests itself in the region around the neutron binding energy and is probably different in nuclei that have different parities of nucleons.« less

Butterflies Do Not Alter Conspecific Avoidance in Response to Variation in Density.

PubMed

Jaumann, Sarah; Snell-Rood, Emilie C

2017-08-01

High conspecific densities are associated with increased levels of intraspecific competition and a variety of negative effects on performance. However, changes in life history strategy could compensate for some of these effects. For instance, females in crowded conditions often have fewer total offspring, but they may invest more in each one. Such investment could include the production of larger offspring, more time spent engaging in parental care, or more choosy decisions about where offspring are placed. For animals that have a relatively immobile juvenile stage, the costs of competition can be particularly high. Females may be able to avoid such costs by investing more in individual reproductive decisions, rearing young or laying eggs in locations away from other females. We tested the hypothesis that conspecific density cues during juvenile and adult life stages lead to changes in life history strategy, including both reproduction and oviposition choices. We predicted that high-density cues during the larval and adult stages of female Pieris rapae butterflies lead to lower fecundity but higher conspecific avoidance during oviposition, compared to similar low-density cues. We used a 2×2 factorial design to examine the effects of low and high conspecific density during the larval and adult stages of butterflies on avoidance behavior and fecundity. We found that past information about conspecific density did not matter; all butterflies exhibited similar levels of fecundity and a low level of conspecific avoidance during oviposition regardless of their previous experience as larvae and adults. These results suggest that P. rapae females use a fixed, rather than flexible, conspecific avoidance strategy when making oviposition decisions, and past information about conspecific density has no effect on life history and current reproductive investment. We speculate that this may be partially because past conspecific density per se is not a reliable cue for predicting current density and levels of competition, and thus it does not affect the development of life history strategies in this system. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Density Functional Calculations of Native Defects in CH 3 NH 3 PbI 3 : Effects of Spin–Orbit Coupling and Self-Interaction Error

DOE PAGES

Du, Mao-Hua

2015-04-02

We know that native point defects play an important role in carrier transport properties of CH3NH3PbI3. However, the nature of many important defects remains controversial due partly to the conflicting results reported by recent density functional theory (DFT) calculations. In this Letter, we show that self-interaction error and the neglect of spin–orbit coupling (SOC) in many previous DFT calculations resulted in incorrect positions of valence and conduction band edges, although their difference, which is the band gap, is in good agreement with the experimental value. Moreover, this problem has led to incorrect predictions of defect-level positions. Hybrid density functional calculations,more » which partially correct the self-interaction error and include the SOC, show that, among native point defects (including vacancies, interstitials, and antisites), only the iodine vacancy and its complexes induce deep electron and hole trapping levels inside of the band gap, acting as nonradiative recombination centers.« less

Magnetic flux density reconstruction using interleaved partial Fourier acquisitions in MREIT.

PubMed

Park, Hee Myung; Nam, Hyun Soo; Kwon, Oh In

2011-04-07

Magnetic resonance electrical impedance tomography (MREIT) has been introduced as a non-invasive modality to visualize the internal conductivity and/or current density of an electrically conductive object by the injection of current. In order to measure a magnetic flux density signal in MREIT, the phase difference approach in an interleaved encoding scheme cancels the systematic artifacts accumulated in phase signals and also reduces the random noise effect. However, it is important to reduce scan duration maintaining spatial resolution and sufficient contrast, in order to allow for practical in vivo implementation of MREIT. The purpose of this paper is to develop a coupled partial Fourier strategy in the interleaved sampling in order to reduce the total imaging time for an MREIT acquisition, whilst maintaining an SNR of the measured magnetic flux density comparable to what is achieved with complete k-space data. The proposed method uses two key steps: one is to update the magnetic flux density by updating the complex densities using the partially interleaved k-space data and the other is to fill in the missing k-space data iteratively using the updated background field inhomogeneity and magnetic flux density data. Results from numerical simulations and animal experiments demonstrate that the proposed method reduces considerably the scanning time and provides resolution of the recovered B(z) comparable to what is obtained from complete k-space data.

Light propagation in Swiss-cheese cosmologies

NASA Astrophysics Data System (ADS)

Szybka, Sebastian J.

2011-08-01

We study the effect of inhomogeneities on light propagation. The Sachs equations are solved numerically in the Swiss-cheese models with inhomogeneities modeled by the Lemaître-Tolman solutions. Our results imply that, within the models we study, inhomogeneities may partially mimic the accelerated expansion of the Universe provided the light propagates through regions with lower than the average density. The effect of inhomogeneities is small and full randomization of the photons’ trajectories reduces it to an insignificant level.

A combined experimental and DFT investigation of disazo dye having pyrazole skeleton

NASA Astrophysics Data System (ADS)

Şener, Nesrin; Bayrakdar, Alpaslan; Kart, Hasan Hüseyin; Şener, İzzet

2017-02-01

Disazo dye containing pyrazole skeleton has been synthesized. The structure of the dye has been confirmed by using FT-IR, 1H NMR, 13C NMR, HRMS spectral technique and elemental analysis. The molecular geometry and infrared spectrum are also calculated by the Density Functional Theory (DFT) employing B3LYP level with 6-311G (d,p) basis set. The chemical shifts calculation for 1H NMR of the title molecule is done by using by Gauge-Invariant Atomic Orbital (GIAO) method by utilizing the same basis sets. The total density of state, the partial density of state and the overlap population density of state diagram analysis are done via Gauss Sum 3.0 program. Frontier molecular orbitals such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and molecular electrostatic potential surface on the title molecule are predicted for various intramolecular interactions that are responsible for the stabilization of the molecule. The experimental results and theoretical values have been compared.

Fermi energy control of vacancy coalescence and dislocation density in melt-grown GaAs

NASA Technical Reports Server (NTRS)

Lagowski, J.; Gatos, H. C.; Lin, D. G.; Aoyama, T.

1984-01-01

A striking effect of the Fermi energy on the dislocation density in melt-grown GaAs has been discovered. Thus, a shift of the Fermi energy from 0.1 eV above to 0.2 eV below its intrinsic value (at high temperature, i.e., near 1100 K) increases the dislocation density by as much as five orders of magnitude. The Fermi energy shift was brought about by n-type and p-type doping at a level of about 10 to the 17th per cu cm (under conditions of optimum partial pressure of As, i.e., under optimum melt stoichiometry). This effect must be associated with the fact that the Fermi energy controls the charge state of vacancies (i.e., the occupancy of the associated electronic states) which in turn must control their tendency to coalesce and thus the dislocation density. It appears most likely that gallium vacancies are the critical species.

Effects of hypobaria and hypoxia on seed germination of six plant species

NASA Astrophysics Data System (ADS)

Tang, Yongkang; Gao, Feng; Guo, Shuangsheng; Li, Fang

2014-10-01

Hypobaria (low pressure) is typically associated with hypoxia (low oxygen partial pressure). There are several advantages of growing higher plants under hypobaria in the moon or mars habitat. The objectives of this research were to investigate the seed germination of six plant species under hypobaric and ambient total pressure conditions. Seeds were sown and germinated under three levels of total atmospheric pressure (101, 30 and 10 kPa) and three levels of oxygen partial pressures (21, 6 and 2 kPa) in an 8-day study. Hypoxia (6 or 2 kPa) significantly inhibited all seed germination under three levels of total atmospheric pressure by increasing the electrical conductivity and the optical density, decreasing the seed germination percentage and seed dehydrogenase activity and inhibiting the growth of the shoots and roots. Hypobaria (30 or 10 kPa) markedly improved seed germination and root growth by enhancing the oxygen diffusion rate under hypoxic conditions (6 or 2 kPa). The seeds of three dicot plants (lettuce, Chinese cabbage and cucumber) were more sensitive to hypoxia caused by hypobaria than were those of three monocot plants (maize, wheat and rice); lettuce and cucumber seeds had the highest sensitivity, whereas rice seeds had the lowest sensitivity. This research demonstrates that six experimental seeds can germinate normally under hypobaria (30 kPa), but the oxygen partial pressure should not be less than 6 kPa.

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

Karabourniotis, D.; Couris, S.; Damelincourt, J.J.

The partial pressure of thallium in high-pressure Hg-TlI discharges with different mercury, thallium, and electron pressures has been measured by using the optically thin line Tl 655 nm and the self-reversed line Tl 535 nm. The partial pressure of the arc axis has been measured from the line Tl 655nm. The effective partial pressure has been measured from the self-reversed line Tl 535 nm on the basis of the multiparameter method, and it has been calculated from the known axis pressure of thallium and the calculation of its radial variation by taking into account the chemical reactions. The experimental resultsmore » confirm the dispersion character of the blue wing of the line Tl 535 nm. The systematic difference obtained between the measured and calculated effective pressure, particularly at the moment of minimum electron density, may be interpreted by deviations from the local thermodynamic equilibrium (LTE) caused by overpopulation of the upper level of the line Tl 535 nm.« less

Physical mechanism of resistance switching in the co-doped RRAM

NASA Astrophysics Data System (ADS)

Yang, Jin; Dai, Yuehua; Lu, Shibin; Jiang, Xianwei; Wang, Feifei; Chen, Junning

2017-01-01

The physical mechanism of the resistance switching for RRAM with co-doped defects (Ag and oxygen vacancy) is studied based on the first principle calculations and the simulation tool VASP. The interaction energy, formation energy and density of states of Ag and oxygen vacancy defect (VO) are calculated. The calculated results reveal that the co-doped system is more stable than the system only doped either Ag or VO defect and the impurity energy levels in the band gap are contributed by Ag and VO defects. The obtained partial charge density confirmed further that the clusters are obvious in the direction of Ag to Hf ions, which means that it is Ag but VO plays a role of conductive paths. For the formation mechanism, the modified electron affinity and the partial charge density difference are calculated. The results show that the ability of electron donors of Ag is stronger than VO In conclusion, the conductivity of the physical mechanism of resistance switching in the co-doped system mainly depends on the doped Ag. Project supported by the National Natural Science Foundation of China (No. 61376106), the Research Foundation of Education Bureau of Anhui Province, China (Nos. KJ2015A276, KJ2016A574, KJ2014A208), and the Special Foundation for Young Scientists of Hefei Normal University (No. 2015rcjj02).

Particle Image Velocimetry Study of Density Current Fronts

ERIC Educational Resources Information Center

Martin, Juan Ezequiel

2009-01-01

Gravity currents are flows that occur when a horizontal density difference causes fluid to move under the action of gravity; density currents are a particular case, for which the scalar causing the density difference is conserved. Flows with a strong effect of the horizontal density difference, even if only partially driven by it--such as the…

Adsorption and Dissociation of Molecular Oxygen on the (0001) Surface of Double Hexagonal Close Packed Americium

NASA Astrophysics Data System (ADS)

Dholabhai, Pratik; Atta-Fynn, Raymond; Ray, Asok

2008-03-01

Oxygen molecule adsorption on (0001) surface of double hexagonal packed americium has been studied in detail within the framework of density functional theory using a full-potential all-electron linearized augmented plane wave plus local orbitals method. The most stable configuration corresponded to molecular dissociation with the oxygen atoms occupying neighboring three-fold hollow h3 sites. Chemisorption energies and adsorption geometries for the adsorbed species, and change in work functions, magnetic moments, partial charges inside muffin-tins, difference charge density distributions and density of states for the bare Am slab and the Am slab after adsorption of the oxygen molecule will be discussed. The effects of chemisorption on Am 5f electron localization-delocalization in the vicinity of the Fermi level and the reaction barrier calculation for the dissociation of oxygen molecule to the most stable h3 sites will be discussed.

On the error in the nucleus-centered multipolar expansion of molecular electron density and its topology: A direct-space computational study.

PubMed

Michael, J Robert; Koritsanszky, Tibor

2017-05-28

The convergence of nucleus-centered multipolar expansion of the quantum-chemical electron density (QC-ED), gradient, and Laplacian is investigated in terms of numerical radial functions derived by projecting stockholder atoms onto real spherical harmonics at each center. The partial sums of this exact one-center expansion are compared with the corresponding Hansen-Coppens pseudoatom (HC-PA) formalism [Hansen, N. K. and Coppens, P., "Testing aspherical atom refinements on small-molecule data sets," Acta Crystallogr., Sect. A 34, 909-921 (1978)] commonly utilized in experimental electron density studies. It is found that the latter model, due to its inadequate radial part, lacks pointwise convergence and fails to reproduce the local topology of the target QC-ED even at a high-order expansion. The significance of the quantitative agreement often found between HC-PA-based (quadrupolar-level) experimental and extended-basis QC-EDs can thus be challenged.

Compressive behavior of fine sand.

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

Martin, Bradley E.; Kabir, Md. E.; Song, Bo

2010-04-01

The compressive mechanical response of fine sand is experimentally investigated. The strain rate, initial density, stress state, and moisture level are systematically varied. A Kolsky bar was modified to obtain uniaxial and triaxial compressive response at high strain rates. A controlled loading pulse allows the specimen to acquire stress equilibrium and constant strain-rates. The results show that the compressive response of the fine sand is not sensitive to strain rate under the loading conditions in this study, but significantly dependent on the moisture content, initial density and lateral confinement. Partially saturated sand is more compliant than dry sand. Similar trendsmore » were reported in the quasi-static regime for experiments conducted at comparable specimen conditions. The sand becomes stiffer as initial density and/or confinement pressure increases. The sand particle size become smaller after hydrostatic pressure and further smaller after dynamic axial loading.« less

On the error in the nucleus-centered multipolar expansion of molecular electron density and its topology: A direct-space computational study

NASA Astrophysics Data System (ADS)

Michael, J. Robert; Koritsanszky, Tibor

2017-05-01

The convergence of nucleus-centered multipolar expansion of the quantum-chemical electron density (QC-ED), gradient, and Laplacian is investigated in terms of numerical radial functions derived by projecting stockholder atoms onto real spherical harmonics at each center. The partial sums of this exact one-center expansion are compared with the corresponding Hansen-Coppens pseudoatom (HC-PA) formalism [Hansen, N. K. and Coppens, P., "Testing aspherical atom refinements on small-molecule data sets," Acta Crystallogr., Sect. A 34, 909-921 (1978)] commonly utilized in experimental electron density studies. It is found that the latter model, due to its inadequate radial part, lacks pointwise convergence and fails to reproduce the local topology of the target QC-ED even at a high-order expansion. The significance of the quantitative agreement often found between HC-PA-based (quadrupolar-level) experimental and extended-basis QC-EDs can thus be challenged.

Partial least squares density modeling (PLS-DM) - a new class-modeling strategy applied to the authentication of olives in brine by near-infrared spectroscopy.

PubMed

Oliveri, Paolo; López, M Isabel; Casolino, M Chiara; Ruisánchez, Itziar; Callao, M Pilar; Medini, Luca; Lanteri, Silvia

2014-12-03

A new class-modeling method, referred to as partial least squares density modeling (PLS-DM), is presented. The method is based on partial least squares (PLS), using a distance-based sample density measurement as the response variable. Potential function probability density is subsequently calculated on PLS scores and used, jointly with residual Q statistics, to develop efficient class models. The influence of adjustable model parameters on the resulting performances has been critically studied by means of cross-validation and application of the Pareto optimality criterion. The method has been applied to verify the authenticity of olives in brine from cultivar Taggiasca, based on near-infrared (NIR) spectra recorded on homogenized solid samples. Two independent test sets were used for model validation. The final optimal model was characterized by high efficiency and equilibrate balance between sensitivity and specificity values, if compared with those obtained by application of well-established class-modeling methods, such as soft independent modeling of class analogy (SIMCA) and unequal dispersed classes (UNEQ). Copyright © 2014 Elsevier B.V. All rights reserved.

Linking removal targets to the ecological effects of invaders: a predictive model and field test.

PubMed

Green, Stephanie J; Dulvy, Nicholas K; Brooks, Annabelle M L; Akins, John L; Cooper, Andrew B; Miller, Skylar; Côté, Isabelle M

Species invasions have a range of negative effects on recipient ecosystems, and many occur at a scale and magnitude that preclude complete eradication. When complete extirpation is unlikely with available management resources, an effective strategy may be to suppress invasive populations below levels predicted to cause undesirable ecological change. We illustrated this approach by developing and testing targets for the control of invasive Indo-Pacific lionfish (Pterois volitans and P. miles) on Western Atlantic coral reefs. We first developed a size-structured simulation model of predation by lionfish on native fish communities, which we used to predict threshold densities of lionfish beyond which native fish biomass should decline. We then tested our predictions by experimentally manipulating lionfish densities above or below reef-specific thresholds, and monitoring the consequences for native fish populations on 24 Bahamian patch reefs over 18 months. We found that reducing lionfish below predicted threshold densities effectively protected native fish community biomass from predation-induced declines. Reductions in density of 25–92%, depending on the reef, were required to suppress lionfish below levels predicted to overconsume prey. On reefs where lionfish were kept below threshold densities, native prey fish biomass increased by 50–70%. Gains in small (<6 cm) size classes of native fishes translated into lagged increases in larger size classes over time. The biomass of larger individuals (>15 cm total length), including ecologically important grazers and economically important fisheries species, had increased by 10–65% by the end of the experiment. Crucially, similar gains in prey fish biomass were realized on reefs subjected to partial and full removal of lionfish, but partial removals took 30% less time to implement. By contrast, the biomass of small native fishes declined by >50% on all reefs with lionfish densities exceeding reef-specific thresholds. Large inter-reef variation in the biomass of prey fishes at the outset of the study, which influences the threshold density of lionfish, means that we could not identify a single rule of thumb for guiding control efforts. However, our model provides a method for setting reef-specific targets for population control using local monitoring data. Our work is the first to demonstrate that for ongoing invasions, suppressing invaders below densities that cause environmental harm can have a similar effect, in terms of protecting the native ecosystem on a local scale, to achieving complete eradication.

An alternative model for a partially coherent elliptical dark hollow beam

NASA Astrophysics Data System (ADS)

Li, Xu; Wang, Fei; Cai, Yangjian

2011-04-01

An alternative theoretical model named partially coherent hollow elliptical Gaussian beam (HEGB) is proposed to describe a partially coherent beam with an elliptical dark hollow profile. Explicit expression for the propagation factors of a partially coherent HEGB is derived. Based on the generalized Collins formula, analytical formulae for the cross-spectral density and mean-squared beam width of a partially coherent HEGB, propagating through a paraxial ABCD optical system, are derived. Propagation properties of a partially coherent HEGB in free space are studied as a numerical example.

Using partially labeled data for normal mixture identification with application to class definition

NASA Technical Reports Server (NTRS)

Shahshahani, Behzad M.; Landgrebe, David A.

1992-01-01

The problem of estimating the parameters of a normal mixture density when, in addition to the unlabeled samples, sets of partially labeled samples are available is addressed. The density of the multidimensional feature space is modeled with a normal mixture. It is assumed that the set of components of the mixture can be partitioned into several classes and that training samples are available from each class. Since for any training sample the class of origin is known but the exact component of origin within the corresponding class is unknown, the training samples as considered to be partially labeled. The EM iterative equations are derived for estimating the parameters of the normal mixture in the presence of partially labeled samples. These equations can be used to combine the supervised and nonsupervised learning processes.

Characterization of Deep and Shallow Levels in GaN

NASA Astrophysics Data System (ADS)

Wessels, Bruce

1997-03-01

The role of native defects and impurities in compensating n-type GaN was investigated. From the observed dependence of carrier concentration on dopant partial pressure the compensating acceptor in n-type material is attributed to the triply charged gallium vacancy. This is consistent with recent calculations on defect stability using density functional theory. The interaction of hydrogen and point defects in GaN was also investigated using FTIR. The role of these defects in compensation will be discussed.

A pilot study showing associations between frequency of CD4(+) memory cell subsets at diagnosis and duration of partial remission in type 1 diabetes.

PubMed

Moya, Rosita; Robertson, Hannah Kathryn; Payne, Dawson; Narsale, Aditi; Koziol, Jim; Davies, Joanna Davida

2016-05-01

In some patients with type 1 diabetes the dose of insulin required to achieve euglycemia is substantially reduced soon after diagnosis. This partial remission is associated with β-cell function and good glucose control. The purpose of this study was to assess whether frequencies of CD4(+) T cell subsets in children newly diagnosed with type 1 diabetes are associated with length of partial remission. We found that the frequency of CD4(+) memory cells, activated Treg cells and CD25(+) cells that express a high density of the IL-7 receptor, CD127 (CD127(hi)) are strongly associated with length of partial remission. Prediction of length of remission via Cox regression is significantly enhanced when CD25(+) CD127(hi) cell frequency is combined with either Insulin Dependent Adjusted A1c (IDAA1c), or glycosylated hemoglobin (HbA1c), or C-peptide levels at diagnosis. CD25(+) CD127(hi) cells do not express Foxp3, LAG-3 and CD49b, indicating that they are neither Treg nor Tr1 cells. Copyright © 2016 Elsevier Inc. All rights reserved.

Stellar model chromospheres. III - Arcturus /K2 III/

NASA Technical Reports Server (NTRS)

Ayres, T. R.; Linsky, J. L.

1975-01-01

Models are constructed for the upper photosphere and chromosphere of Arcturus based on the H, K, and IR triplet lines of Ca II and the h and k lines of Mg II. The chromosphere model is derived from complete redistribution solutions for a five-level Ca II ion and a two-level Mg II ion. A photospheric model is derived from the Ca II wings using first the 'traditional' complete-redistribution limit and then the more realistic partial-redistribution approximation. The temperature and mass column densities for the temperature-minimum region and the chromosphere-transition region boundary are computed, and the pressure in the transition region and corona are estimated. It is found that the ratio of minimum temperature to effective temperature is approximately 0.77 for Arcturus, Procyon, and the sun, and that mass tends to increase at the temperature minimum with decreasing gravity. The pressure is found to be about 1 percent of the solar value, and the surface brightness of the Arcturus transition region and coronal spectrum is estimated to be much less than for the sun. The partial-redistribution calculation for the Ca II K line indicates that the emission width is at least partially determined by damping rather than Doppler broadening, suggesting a reexamination of previous explanations for the Wilson-Bappu effect.

Mast cell curve-response in partial Achilles tendon rupture after 830 nm phototherapy.

PubMed

Pinfildi, Carlos E; da Silva, Érika P Rampazo; Folha, Roberta A C; Turchetto, Paola C G; Monteiro, Paola Pkp; Antunes, Arainy; Hochman, Bernardo S

2014-02-01

The aim of this study was to quantify mast cells at different time intervals after partial Achilles tendon rupture in rats treated with low-level laser therapy (LLLT). There is a high incidence of lesions and ruptures in the Achilles tendon that can take weeks and even months to heal completely. As the mast cells help in the healing repair phase, and LLLT has favorable effects on this tissue repair process, study of this modality on the quantity of mastocytes in the ruptured tendon is relevant. Sixty Wistar rats were subjected to partial Achilles' tendon rupture by direct trauma, randomized into 10 groups, and then divided into the group treated with 80 mW aluminum gallium arsenide infrared laser diode, continuous wave, 2.8 W/cm(2) power density, 40 J/cm(2) energy density, and 1.12 J total energy, and the simulation group. Both the groups were subdivided according to the histological assessment period of the sample, either 6 h, 12 h, 24 h, 2 days, or 3 days after the rupture, to quantify the mastocytes in the Achilles' tendon. The group subjected to LLLT presented a greater quantity of mastocytes in the periods of 6 h, 12 h, 24 h, 2 days, and 3 days after rupture, compared with the simulation groups, but differences were detected between the sample assessment periods only in the simulation group. LLLT was shown to increase the quantity of mastocytes in the assessment periods compared with the simulation groups.

Compositional dependent partial molar volume and compressibility of CO2 in rhyolite, phonolite and basalt glasses

NASA Astrophysics Data System (ADS)

Lerch, P.; Seifert, R.; Malfait, W. J.; Sanchez-Valle, C.

2012-12-01

Carbon dioxide is the second most abundant volatile in magmatic systems and plays an important role in many magmatic processes, e.g. partial melting, volatile saturation, outgassing. Despite this relevance, the volumetric properties of carbon-bearing silicates at relevant pressure and temperature conditions remain largely unknown because of considerable experimental difficulties associated with in situ measurements. Density and elasticity measurements on quenched glasses can provide an alternative source of information. For dissolved water, such measurements indicate that the partial molar volume is independent of compositions at ambient pressure [1], but the partial molar compressibility is not [2, 3]. Thus the partial molar volume of water may depend on melt composition at elevated pressure. For dissolved CO2, no such data is available. In order to constrain the effect of magma composition on the partial molar volume and compressibility of dissolved carbon, we determined the density and elasticity for three series of carbon-bearing basalt, phonolite and rhyolite glasses, quenched from 3.5 GPa and relaxed at ambient pressure. The CO2 content varies between 0 to 3.90 wt% depending on the glass composition. Glass densities were determined using the sink/float method in a diiodomethane (CH2I2) - acetone mixture. Brillouin measurements were conducted on relaxed and unrelaxed silicate glasses in platelet geometry to determine the compressional (VP) and shear (VS) wave velocities and elastic moduli. The partial molar volume of CO2 in rhyolite, phonolite and basalt glasses is 25.4 ± 0.9, 22.1 ± 0.6 and 26.6 ±1.8 cm3/mol, respectively. Thus, unlike for dissolved water, the partial molar volume of CO2 displays a resolvable compositional effect. Although the composition and CO2/carbonate speciation of the phonolite glasses is intermediate between that of the rhyolite and basalt glasses, the molar volume is not. Similar to dissolved water, the partial molar bulk modulus of CO2 displays a strong compositional effect. If these compositional dependencies persist in the analogue melts, the partial molar volume of dissolved CO2 will depend on melt composition, both at low and elevated pressure. Thus, for CO2-bearing melts, a full quantitative understanding of density dependent magmatic processes, such as crystal fractionation, magma mixing and melt extraction will require in situ measurements for a range of melt compositions. [1] Richet, P. et al., 2000, Contrib Mineral Petrol, 138, 337-347. [2] Malfait et al. 2011, Am. Mineral. 96, 1402-1409. [3] Whittington et al., 2012, Am. Mineral. 97, 455-467.

A partial differential equation for pseudocontact shift.

PubMed

Charnock, G T P; Kuprov, Ilya

2014-10-07

It is demonstrated that pseudocontact shift (PCS), viewed as a scalar or a tensor field in three dimensions, obeys an elliptic partial differential equation with a source term that depends on the Hessian of the unpaired electron probability density. The equation enables straightforward PCS prediction and analysis in systems with delocalized unpaired electrons, particularly for the nuclei located in their immediate vicinity. It is also shown that the probability density of the unpaired electron may be extracted, using a regularization procedure, from PCS data.

Electronic and thermodynamic properties of layered Hf2Sfrom first-principles calculations

NASA Astrophysics Data System (ADS)

Nandadasa, Chandani; Yoon, Mina; Kim, Seong-Gon; Erwin, Steve; Kim, Sungho; Kim, Sung Wng; Lee, Kimoon

Theoretically we explored two stable phases of inorganic fullerene-like structure of the layered dihafnium sulfide (Hf2 S) . We investigated structural and electronic properties of the two phases of Hf2 S by using first-principles calculations. Our calculation identifies experimentally observed anti-NbS2 structure of Hf2 S . Our electronic calculation results indicate that the density of states of anti- NbS2 structure of Hf2 S at fermi level is less than that of the other phase of Hf2 S . To study the relative stability of different phases at finite temperature Helmholtz free energies of two phases are obtained using density functional theory and density functional perturbation theory. The free energy of the anti-NbS2 structure of Hf2 S always lies below the free energy of the other phase by confirming the most stable structure of Hf2 S . The phonon dispersion, phonon density of states including partial density of states and total density of states are obtained within density functional perturbation theory. Our calculated zero-pressure phonon dispersion curves confirm that the thermodynamic stability of Hf2 S structures. For further investigation of thermodynamic properties, the temperature dependency of thermal expansion, heat capacities at constant pressure and volume are evaluated within the quasiharmonic approximations (QHA).

Error Budgeting

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

Vinyard, Natalia Sergeevna; Perry, Theodore Sonne; Usov, Igor Olegovich

2017-10-04

We calculate opacity from k (hn)=-ln[T(hv)]/pL, where T(hv) is the transmission for photon energy hv, p is sample density, and L is path length through the sample. The density and path length are measured together by Rutherford backscatter. Δk =more » $$\\partial k$$\\ $$\\partial T$$ ΔT + $$\\partial k$$\\ $$\\partial (pL)$$. We can re-write this in terms of fractional error as Δk/k = Δ1n(T)/T + Δ(pL)/(pL). Transmission itself is calculated from T=(U-E)/(V-E)=B/B0, where B is transmitted backlighter (BL) signal and B 0 is unattenuated backlighter signal. Then ΔT/T=Δln(T)=ΔB/B+ΔB 0/B 0, and consequently Δk/k = 1/T (ΔB/B + ΔB$$_0$$/B$$_0$$ + Δ(pL)/(pL). Transmission is measured in the range of 0.2« less

Stability of Nonstationary Cooling of Pure Hydrogen Gas with Respect to the Number of Discrete Levels Taken into Account

NASA Astrophysics Data System (ADS)

Belova, O. M.; Bychkov, K. V.

2018-03-01

The effect of the number K of atomic hydrogen levels taken into account on the cooling of the gas behind a shock front is studied. The calculations are done for the conditions in the atmospheres of long-period Mira Ceti type variables. K ranges from 2 to 25. The electron temperature Te(t; K) and ionization state x(r,K) asymptotically approach limiting functions Te(t) and x(t) that are independent of K. After the maximum electron temperature is reached, a partial equilibrium phase sets in, during which the populations of the highly excited discrete levels with principal quantum numbers ≥ 8 obey the Saha equation for the instantaneous electron temperature and density.

A spatial analysis of social and economic determinants of tuberculosis in Brazil.

PubMed

Harling, Guy; Castro, Marcia C

2014-01-01

We investigated the spatial distribution, and social and economic correlates, of tuberculosis in Brazil between 2002 and 2009 using municipality-level age/sex-standardized tuberculosis notification data. Rates were very strongly spatially autocorrelated, being notably high in urban areas on the eastern seaboard and in the west of the country. Non-spatial ecological regression analyses found higher rates associated with urbanicity, population density, poor economic conditions, household crowding, non-white population and worse health and healthcare indicators. These associations remained in spatial conditional autoregressive models, although the effect of poverty appeared partially confounded by urbanicity, race and spatial autocorrelation, and partially mediated by household crowding. Our analysis highlights both the multiple relationships between socioeconomic factors and tuberculosis in Brazil, and the importance of accounting for spatial factors in analysing socioeconomic determinants of tuberculosis. © 2013 Published by Elsevier Ltd.

Electronic structure and partial charge distribution of Doxorubicin in different molecular environments.

PubMed

Poudel, Lokendra; Wen, Amy M; French, Roger H; Parsegian, V Adrian; Podgornik, Rudolf; Steinmetz, Nicole F; Ching, Wai-Yim

2015-05-18

The electronic structure and partial charge of doxorubicin (DOX) in three different molecular environments-isolated, solvated, and intercalated in a DNA complex-are studied by first-principles density functional methods. It is shown that the addition of solvating water molecules to DOX, together with the proximity to and interaction with DNA, has a significant impact on the electronic structure as well as on the partial charge distribution. Significant improvement in estimating the DOX-DNA interaction energy is achieved. The results are further elucidated by resolving the total density of states and surface charge density into different functional groups. It is concluded that the presence of the solvent and the details of the interaction geometry matter greatly in determining the stability of DOX complexation. Ab initio calculations on realistic models are an important step toward a more accurate description of the long-range interactions in biomolecular systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single- and multiple-pulse noncoherent detection statistics associated with partially developed speckle.

PubMed

Osche, G R

2000-08-20

Single- and multiple-pulse detection statistics are presented for aperture-averaged direct detection optical receivers operating against partially developed speckle fields. A partially developed speckle field arises when the probability density function of the received intensity does not follow negative exponential statistics. The case of interest here is the target surface that exhibits diffuse as well as specular components in the scattered radiation. An approximate expression is derived for the integrated intensity at the aperture, which leads to single- and multiple-pulse discrete probability density functions for the case of a Poisson signal in Poisson noise with an additive coherent component. In the absence of noise, the single-pulse discrete density function is shown to reduce to a generalized negative binomial distribution. The radar concept of integration loss is discussed in the context of direct detection optical systems where it is shown that, given an appropriate set of system parameters, multiple-pulse processing can be more efficient than single-pulse processing over a finite range of the integration parameter n.

Partial molar volumes and viscosities of aqueous hippuric acid solutions containing LiCl and MnCl2 · 4H2O at 303.15 K

NASA Astrophysics Data System (ADS)

Deosarkar, S. D.; Tawde, P. D.; Zinjade, A. B.; Shaikh, A. I.

2015-09-01

Density (ρ) and viscosity (η) of aqueous hippuric acid (HA) solutions containing LiCl and MnCl2 · 4H2O have been studied at 303.15 K in order to understand volumetric and viscometric behavior of these systems. Apparent molar volume (φv) of salts were calculated from density data and fitted to Massons relation and partial molar volumes (φ{v/0}) at infinite dilution were determined. Relative viscosity data has been used to determine viscosity A and B coefficients using Jones-Dole relation. Partial molar volume and viscosity coefficients have been discussed in terms of ion-solvent interactions and overall structural fittings in solution.

The role of single immediate loading implant in long Class IV Kennedy mandibular partial denture.

PubMed

Mohamed, Gehan F; El Sawy, Amal A

2012-10-01

The treatment of long-span Kennedy class IV considers a prosthodontic challenge. This study evaluated the integrity of principle abutments in long Kennedy class IV clinically and radiographically, when rehabilitated with conventional metallic partial denture as a control group and mandibular partial overdentures supported with single immediately loaded implant in symphyseal as a study group. Twelve male patients were divided randomly allotted into two equal groups. First group patients received removable metallic partial denture, whereas in the second group, patients received partial overdentures supported with single immediately loaded implant in symphyseal region. The partial dentures design in both groups was the same. Long-cone paralleling technique and transmission densitometer were used at the time of denture insertion, 3, 6, and 12 months. Gingival index, bone loss, and optical density were measured for principle abutments during the follow-up. A significant reduction in bone loss and density were detected in group II comparing with group I. Gingival index had no significant change (p-value < 0.05). A single symphyseal implant in long span class IV Kennedy can play a pivotal role to improve the integrity of the principle abutments and alveolar bone support. © 2010 Wiley Periodicals, Inc.

The puzzle of partial migration: Adaptive dynamics and evolutionary game theory perspectives.

PubMed

De Leenheer, Patrick; Mohapatra, Anushaya; Ohms, Haley A; Lytle, David A; Cushing, J M

2017-01-07

We consider the phenomenon of partial migration which is exhibited by populations in which some individuals migrate between habitats during their lifetime, but others do not. First, using an adaptive dynamics approach, we show that partial migration can be explained on the basis of negative density dependence in the per capita fertilities alone, provided that this density dependence is attenuated for increasing abundances of the subtypes that make up the population. We present an exact formula for the optimal proportion of migrants which is expressed in terms of the vital rates of migrant and non-migrant subtypes only. We show that this allocation strategy is both an evolutionary stable strategy (ESS) as well as a convergence stable strategy (CSS). To establish the former, we generalize the classical notion of an ESS because it is based on invasion exponents obtained from linearization arguments, which fail to capture the stabilizing effects of the nonlinear density dependence. These results clarify precisely when the notion of a "weak ESS", as proposed in Lundberg (2013) for a related model, is a genuine ESS. Secondly, we use an evolutionary game theory approach, and confirm, once again, that partial migration can be attributed to negative density dependence alone. In this context, the result holds even when density dependence is not attenuated. In this case, the optimal allocation strategy towards migrants is the same as the ESS stemming from the analysis based on the adaptive dynamics. The key feature of the population models considered here is that they are monotone dynamical systems, which enables a rather comprehensive mathematical analysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electronic structure of the organic semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from soft x-ray spectroscopies and density functional theory calculations.

PubMed

DeMasi, A; Piper, L F J; Zhang, Y; Reid, I; Wang, S; Smith, K E; Downes, J E; Peltekis, N; McGuinness, C; Matsuura, A

2008-12-14

The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq(3)) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq(3), and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studies and the present data reveal the presence of clear photon-induced damage in the former.

Multi-Dimensional Quantum Effect Simulation Using a Density-Gradient Model and Script-Level Programming Techniques

NASA Technical Reports Server (NTRS)

Rafferty, Connor S.; Biegel, Bryan A.; Yu, Zhi-Ping; Ancona, Mario G.; Bude, J.; Dutton, Robert W.; Saini, Subhash (Technical Monitor)

1998-01-01

A density-gradient (DG) model is used to calculate quantum-mechanical corrections to classical carrier transport in MOS (Metal Oxide Semiconductor) inversion/accumulation layers. The model is compared to measured data and to a fully self-consistent coupled Schrodinger and Poisson equation (SCSP) solver. Good agreement is demonstrated for MOS capacitors with gate oxide as thin as 21 A. It is then applied to study carrier distribution in ultra short MOSFETs (Metal Oxide Semiconductor Field Effect Transistor) with surface roughness. This work represents the first implementation of the DG formulation on multidimensional unstructured meshes. It was enabled by a powerful scripting approach which provides an easy-to-use and flexible framework for solving the fourth-order PDEs (Partial Differential Equation) of the DG model.

Fingerprint Ridge Density as a Potential Forensic Anthropological Tool for Sex Identification.

PubMed

Dhall, Jasmine Kaur; Kapoor, Anup Kumar

2016-03-01

In cases of partial or poor print recovery and lack of database/suspect print, fingerprint evidence is generally neglected. In light of such constraints, this study was designed to examine whether ridge density can aid in narrowing down the investigation for sex identification. The study was conducted on the right-hand index digit of 245 males and 246 females belonging to the Punjabis of Delhi region. Five ridge density count areas, namely upper radial, radial, ulnar, upper ulnar, and proximal, were selected and designated. Probability of sex origin was calculated, and stepwise discriminant function analysis was performed to determine the discriminating ability of the selected areas. Females were observed with a significantly higher ridge density than males in all the five areas. Discriminant function analysis and logistic regression exhibited 96.8% and 97.4% accuracy, respectively, in sex identification. Hence, fingerprint ridge density is a potential tool for sex identification, even from partial prints. © 2015 American Academy of Forensic Sciences.

Anti-TNFα therapy transiently improves high density lipoprotein cholesterol levels and microvascular endothelial function in patients with rheumatoid arthritis: a Pilot Study

PubMed Central

2012-01-01

Background Rheumatoid arthritis (RA) is associated with increased morbidity and mortality from cardiovascular disease (CVD). This can be only partially attributed to traditional CVD risk factors such as dyslipidaemia and their downstream effects on endothelial function. The most common lipid abnormality in RA is reduced levels of high-density lipoprotein (HDL) cholesterol, probably due to active inflammation. In this longitudinal study we hypothesised that anti-tumor necrosis factor-α (anti-TNFα) therapy in patients with active RA improves HDL cholesterol, microvascular and macrovascular endothelial function. Methods Twenty-three RA patients starting on anti-TNFα treatment were assessed for HDL cholesterol level, and endothelial-dependent and -independent function of microvessels and macrovessels at baseline, 2-weeks and 3 months of treatment. Results Disease activity (CRP, fibrinogen, DAS28) significantly decreased during the follow-up period. There was an increase in HDL cholesterol levels at 2 weeks (p < 0.05) which was paralleled by a significant increase in microvascular endothelial-dependent function (p < 0.05). However, both parameters returned towards baseline at 12 weeks. Conclusion Anti-TNFα therapy in RA patients appears to be accompanied by transient but significant improvements in HDL cholesterol levels, which coexists with an improvement in microvascular endothelial-dependent function. PMID:22824166

The density, compressibility and seismic velocity of hydrous melts at crustal and upper mantle conditions

NASA Astrophysics Data System (ADS)

Ueki, K.; Iwamori, H.

2015-12-01

Various processes of subduction zone magmatism, such as upward migration of partial melts and fractional crystallization depend on the density of the hydrous silicate melt. The density and the compressibility of the hydrous melt are key factors for the thermodynamic calculation of phase relation of the hydrous melt, and the geophysical inversion to predict physicochemical conditions of the melting region based on the seismic velocity. This study presents a new model for the calculations of the density of the hydrous silicate melts as a function of T, P, H2O content and melt composition. The Birch-Murnaghan equation is used for the equation of state. We compile the experimentally determined densities of various hydrous melts, and optimize the partial molar volume, compressibility, thermal expansibility and its pressure derivative, and K' of the H2O component in the silicate melt. P-T ranges of the calibration database are 0.48-4.29 GPa and 1033-2073 K. As such, this model covers the P-T ranges of the entire melting region of the subduction zone. Parameter set provided by Lange and Carmichael [1990] is used for the partial molar volume and KT value of the anhydrous silicate melt. K' of anhydrous melt is newly parameterized as a function of SiO2 content. The new model accurately reproduces the experimentally determined density variations of various hydrous melts from basalt to rhyolite. Our result shows that the hydrous melt is more compressive and less dense than the anhydrous melt; with the 5 wt% of H2O in melt, density and KT decrease by ~10% and ~30% from those of the anhydrous melt, respectively. For the application of the model, we calculated the P-wave velocity of the hydrous melt. With the 5 wt% of H2O, P-wave velocity of the silicate melt decreases by >10%. Based on the melt P-wave velocity, we demonstrate the effect of the melt H2O content on the seismic velocity of the partially molten zone of the subduction zone.

A critical analysis of methods for rapid and nondestructive determination of wood density in standing trees

Treesearch

Shan Gao; Xiping Wang; Michael C. Wiemann; Brian K. Brashaw; Robert J. Ross; Lihai Wang

2017-01-01

Key message Field methods for rapid determination of wood density in trees have evolved from increment borer, torsiometer, Pilodyn, and nail withdrawal into sophisticated electronic tools of resistance drilling measurement. A partial resistance drilling approach coupled with knowledge of internal tree density distribution may...

[Carbon density distribution characteristics and influencing factors in aerially seeded Pinus massoniana plantations].

PubMed

Pan, Ping; Han, Tian Yi; OuYang, Xun Zhi; Liu, Yuan Qiu; Zang, Hao; Ning, Jin Kui; Yang, Yang

2017-12-01

The distribution characteristics of carbon density under aerially seeded Pinus massoniana plantations in Ganzhou City of Jiangxi Province were studied. Total 15 factors, including site, stand, understory vegetation, litter and so on were selected to establish a relationship model between stand carbon density and influencing factors, and the main influencing factors were also screened. The results showed that the average carbon density was 98.29 t·hm -2 at stand level with soil layer (49.58 t·hm -2 ) > tree layer (45.25 t·hm -2 ) > understory vegetation layer (2.23 t·hm -2 ) > litter layer (1.23 t·hm -2 ). Significantly positive correlations were found among the tree, litter and soil layers, but not among the other layers. The main factors were tree density, avera-ge diameter at breast height (DBH), soil thickness, slope position, stand age and canopy density to affect carbon density in aerially seeded P. massoniana plantations. The partial correlation coefficients of the six main factors ranged from 0.331 to 0.434 with significance by t test. The multiple correlation coefficient of quantitative model I reached 0.796 with significance by F test (F=9.28). For stand density, the best tree density and canopy density were 1500-2100 plants·hm -2 and 0.4-0.7, respectively. The moderate density was helpful to improve ecosystem carbon sequestration. The carbon density increased with increasing stand age, DBH and soil thickness, and was higher in lower than middle and upper slope positions.

Electronic Structure of the Organic Semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from Soft X-ray Spectroscopies and Density Functional Theory Calculations

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

DeMasi, A.; Piper, L; Zhang, Y

2008-01-01

The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq3) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq3, and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studiesmore » and the present data reveal the presence of clear photon-induced damage in the former.« less

The collisional drift mode in a partially ionized plasma. [in the F region

NASA Technical Reports Server (NTRS)

Hudson, M. K.; Kennel, C. F.

1974-01-01

The structure of the drift instability was examined in several density regimes. Let sub e be the total electron mean free path, k sub z the wave-vector component along the magnetic field, and the ratio of perpendicular ion diffusion to parallel electron streaming rates. At low densities (k sub z lambda 1) the drift mode is isothermal and should be treated kineticly. In the finite heat conduction regime square root of m/M k sub z Lambda sub 1) the drift instability threshold is reduced at low densities and increased at high densities as compared to the isothermal threshold. Finally, in the energy transfer limit (k sub z kambda sub e square root of m/M) the drift instability behaves adiabatically in a fully ionized plasma and isothermally in a partially ionized plasma for an ion-neutral to Coulomb collision frequency ratio.

Human Peripheral Blood Mononuclear Cells Exhibit Heterogeneous CD52 Expression Levels and Show Differential Sensitivity to Alemtuzumab Mediated Cytolysis

PubMed Central

Rao, Sambasiva P.; Sancho, Jose; Campos-Rivera, Juanita; Boutin, Paula M.; Severy, Peter B.; Weeden, Timothy; Shankara, Srinivas; Roberts, Bruce L.; Kaplan, Johanne M.

2012-01-01

Alemtuzumab is a monoclonal antibody that targets cell surface CD52 and is effective in depleting lymphocytes by cytolytic effects in vivo. Although the cytolytic effects of alemtuzumab are dependent on the density of CD52 antigen on cells, there is scant information regarding the expression levels of CD52 on different cell types. In this study, CD52 expression was assessed on phenotypically distinct subsets of lymphoid and myeloid cells in peripheral blood mononuclear cells (PBMCs) from normal donors. Results demonstrate that subsets of PBMCs express differing levels of CD52. Quantitative analysis showed that memory B cells and myeloid dendritic cells (mDCs) display the highest number while natural killer (NK) cells, plasmacytoid dendritic cells (pDCs) and basophils have the lowest number of CD52 molecules per cell amongst lymphoid and myeloid cell populations respectively. Results of complement dependent cytolysis (CDC) studies indicated that alemtuzumab mediated profound cytolytic effects on B and T cells with minimal effect on NK cells, basophils and pDCs, correlating with the density of CD52 on these cells. Interestingly, despite high CD52 levels, mDCs and monocytes were less susceptible to alemtuzumab-mediated CDC indicating that antigen density alone does not define susceptibility. Additional studies indicated that higher expression levels of complement inhibitory proteins (CIPs) on these cells partially contributes to their resistance to alemtuzumab mediated CDC. These results indicate that alemtuzumab is most effective in depleting cells of the adaptive immune system while leaving innate immune cells relatively intact. PMID:22761788

Measuring interdependence in ambulatory care.

PubMed

Katerndahl, David; Wood, Robert; Jaen, Carlos R

2017-04-01

Complex systems differ from complicated systems in that they are nonlinear, unpredictable and lacking clear cause-and-effect relationships, largely due to the interdependence of their components (effects of interconnectedness on system behaviour and consequences). The purpose of this study was to demonstrate the potential for network density to serve as a measure of interdependence, assess its concurrent validity and test whether the use of valued or binary ties yields better results. This secondary analysis used the 2010 National Ambulatory Care Medical Survey to assess interdependence of 'top 20' diagnoses seen and medications prescribed for 14 specialties. The degree of interdependence was measured as the level of association between diagnoses and drug interactions among medications. Both valued and binary network densities were computed for each specialty. To assess concurrent validity, these measures were correlated with previously-derived valid measures of complexity of care using the same database, adjusting for diagnosis and medication diversity. Partial correlations between diagnosis density, and both diagnosis and total input complexity, were significant, as were those between medication density and both medication and total output complexity; for both diagnosis and medication densities, adjusted correlations were higher for binary rather than valued densities. This study demonstrated the feasibility and validity of using network density as a measure of interdependence. When adjusted for measure diversity, density-complexity correlations were significant and higher for binary than valued density. This approach complements other methods of estimating complexity of care and may be applicable to unique settings. © 2015 John Wiley & Sons, Ltd.

Low-Temperature Thermoelectric Properties of Fe2VAl with Partial Cobalt Doping

NASA Astrophysics Data System (ADS)

Liu, Chang; Morelli, Donald T.

2012-06-01

Ternary metallic alloy Fe2VAl with a pseudogap in its energy band structure has received intensive scrutiny for potential thermoelectric applications. Due to the sharp change in the density of states profile near the Fermi level, interesting transport properties can be triggered to render possible enhancement in the overall thermoelectric performance. Previously, this full-Heusler-type alloy was partially doped with cobalt at the iron sites to produce a series of compounds with n-type conductivity. Their thermoelectric properties in the temperature range of 300 K to 850 K were reported. In this research, efforts were made to extend the investigation on (Fe1- x Co x )2VAl to the low-temperature range. Alloy samples were prepared by arc-melting and annealing. Seebeck coefficient, electrical resistivity, and thermal conductivity measurements were performed from 80 K to room temperature. The effects of cobalt doping on the material's electronic and thermal properties are discussed.

Density contrast sedimentation velocity for the determination of protein partial-specific volumes.

PubMed

Brown, Patrick H; Balbo, Andrea; Zhao, Huaying; Ebel, Christine; Schuck, Peter

2011-01-01

The partial-specific volume of proteins is an important thermodynamic parameter required for the interpretation of data in several biophysical disciplines. Building on recent advances in the use of density variation sedimentation velocity analytical ultracentrifugation for the determination of macromolecular partial-specific volumes, we have explored a direct global modeling approach describing the sedimentation boundaries in different solvents with a joint differential sedimentation coefficient distribution. This takes full advantage of the influence of different macromolecular buoyancy on both the spread and the velocity of the sedimentation boundary. It should lend itself well to the study of interacting macromolecules and/or heterogeneous samples in microgram quantities. Model applications to three protein samples studied in either H(2)O, or isotopically enriched H(2) (18)O mixtures, indicate that partial-specific volumes can be determined with a statistical precision of better than 0.5%, provided signal/noise ratios of 50-100 can be achieved in the measurement of the macromolecular sedimentation velocity profiles. The approach is implemented in the global modeling software SEDPHAT.

Examination of N*(1535 ) as a probe to observe the partial restoration of chiral symmetry in nuclear matter

NASA Astrophysics Data System (ADS)

Suenaga, Daiki

2018-04-01

I investigate modifications of mass and decay width of N*(1535 ) in nuclear matter in a chiral symmetric way. The nucleon and N*(1535 ) are introduced by a parity doublet model, and nuclear matter is constructed by one-loop diagrams of the nucleon and N*(1535 ) . The decay width of N*(1535 ) is studied with respect to chiral symmetry. My calculations show that the partial width of ΓN*→N π is slightly broadened by a collisional broadening and that of ΓN*→N η is drastically suppressed at density. As a result, the total decay width Γtot gets small at density. These modifications, especially the drastic narrowing of partial width of ΓN*→N η, together with the drop in mass of N*(1535 ) , provide experiments for observing the partial restoration of chiral symmetry in nuclear matter by means of N*(1535 ) resonance with useful information.

Electrodeposition of nickel-iridium alloy films from aqueous solutions

NASA Astrophysics Data System (ADS)

Wu, Wangping; Jiang, Jinjin; Jiang, Peng; Wang, Zhizhi; Yuan, Ningyi; Ding, Jianning

2018-03-01

Nickel-iridium (Ni-Ir) alloy films were electrodeposited from aqueous solutions on copper substrates under galvanostatic conditions. The effects of bath composition and deposition time on the faradaic efficiency (FE), partial current densities, chemical composition, morphology and crystallographic structure of the films were studied. The results show that the Ni-Ir alloys with Ir content as high as 37 at% and FE as high as 44% were obtained. Increase in concentration of citric acid had little or no effect on the composition of the alloys, but resulted in a significant decrease in FE and partial current densities of Ni and Ir. The FE and the partial current density of Ni slightly decreased with increasing Ir3+ concentration, however, Ir content increased while partial current density of Ir remained stable. The increase of Ni2+ concentration could result in the increase of the FE and the rate of Ni-Ir deposition, and even no cracks formed on the surface. The surface average roughness and root mean square roughness of the film were 6.8 ± 0.3 nm and 5.4 ± 0.3 nm, respectively. The mixture phases contained significant amounts of Ni oxides and a small amount of metallic Ni, Ir and Ir oxides on the surface. After argon ion sputter cleaning, the film was mainly composed of metallic Ni and Ir. The film consisted of the amorphous and nanocrystalline phases. The Ni content in the deposits was higher than that in the electrolyte, the co-deposition of Ni-Ir alloy was a normal deposition.

Endometrial vessel maturation in women exposed to levonorgestrel-releasing intrauterine system for a short or prolonged period of time.

PubMed

Stéphanie, Ravet; Labied, Soraya; Blacher, Silvia; Frankenne, Francis; Munaut, Carine; Fridman, Viviana; Beliard, Aude; Foidart, Jean-Michel; Nisolle, Michelle

2007-12-01

Levonorgestrel-releasing intrauterine system (LNG-IUS), although inserted to reduce heavy menstruation, causes irregular early transient bleeding. The objective of the study was to document quantitative changes in endometrial vessels of short- (< or =3 months) and long-term (> or =12 months) LNG users. The area, density and maturation of endometrial vessels were quantified in 19 endometrial biopsies of women with LNG-IUS and in 10 normally ovulating patients during mid-luteal phase. Vessel maturation was evaluated by double immunostaining using anti-von Willebrand factor (endothelial cell marker) and anti-alpha Smooth Muscle Actin (vascular smooth muscle cells) antibodies. Vessel area, number and density were quantified with a novel computer-assisted image analysis system. Endometrium exposed to LNG-IUS for 1-3 months displayed a 11.5-fold increase in small naked vessel number. The partially mature vessel (alphaSMA partially positive) number increased six times. After long-term LNG-IUS treatment, the immature and partially mature vessel number remained four times higher than in the control group. Vessel area and density also increased dramatically in a time-dependent pattern with LNG-IUS use. Levonorgestrel affects blood vessel number, area, density and maturation in a time-dependent pattern that may explain the early transient increase in breakthrough bleeding with the LNG-IUS.

Utility of a Multiparametric Quantitative MRI Model That Assesses Myelin and Edema for Evaluating Plaques, Periplaque White Matter, and Normal-Appearing White Matter in Patients with Multiple Sclerosis: A Feasibility Study.

PubMed

Hagiwara, A; Hori, M; Yokoyama, K; Takemura, M Y; Andica, C; Kumamaru, K K; Nakazawa, M; Takano, N; Kawasaki, H; Sato, S; Hamasaki, N; Kunimatsu, A; Aoki, S

2017-02-01

T1 and T2 values and proton density can now be quantified on the basis of a single MR acquisition. The myelin and edema in a voxel can also be estimated from these values. The purpose of this study was to evaluate a multiparametric quantitative MR imaging model that assesses myelin and edema for characterizing plaques, periplaque white matter, and normal-appearing white matter in patients with MS. We examined 3T quantitative MR imaging data from 21 patients with MS. The myelin partial volume, excess parenchymal water partial volume, the inverse of T1 and transverse T2 relaxation times (R1, R2), and proton density were compared among plaques, periplaque white matter, and normal-appearing white matter. All metrics differed significantly across the 3 groups ( P < .001). Those in plaques differed most from those in normal-appearing white matter. The percentage changes of the metrics in plaques and periplaque white matter relative to normal-appearing white matter were significantly more different from zero for myelin partial volume (mean, -61.59 ± 20.28% [plaque relative to normal-appearing white matter], and mean, -10.51 ± 11.41% [periplaque white matter relative to normal-appearing white matter]), and excess parenchymal water partial volume (13.82 × 10 3 ± 49.47 × 10 3 % and 51.33 × 10 2 ± 155.31 × 10 2 %) than for R1 (-35.23 ± 13.93% and -6.08 ± 8.66%), R2 (-21.06 ± 11.39% and -4.79 ± 6.79%), and proton density (23.37 ± 10.30% and 3.37 ± 4.24%). Multiparametric quantitative MR imaging captures white matter damage in MS. Myelin partial volume and excess parenchymal water partial volume are more sensitive to the MS disease process than R1, R2, and proton density. © 2017 by American Journal of Neuroradiology.

Effect of oxygen partial pressure on the density of antiphase boundaries in Fe3O4 thin films on Si(100)

NASA Astrophysics Data System (ADS)

Singh, Suraj Kumar; Husain, Sajid; Kumar, Ankit; Chaudhary, Sujeet

2018-02-01

Polycrystalline Fe3O4 thin films were grown on Si(100) substrate by reactive DC sputtering at different oxygen partial pressures PO2 for controlling the growth associated density of antiphase boundaries (APBs). The micro-Raman analyses were performed to study the structural and electronic properties in these films. The growth linked changes in the APBs density are probed by electron-phonon coupling strength (λ) and isothermal magnetization measurements. The estimated values of λ are found to vary from 0.39 to 0.56 with the increase in PO2 from 2.2 × 10-5 to 3.0 × 10-5 Torr, respectively. The saturation magnetization (saturation field) values are found to increase (decrease) from 394 (5.9) to 439 (3.0) emu/cm3 (kOe) with the increase in PO2 . The sharp Verwey transition (∼120 K), low saturation field, high saturation magnetization and low value of λ (comparable to the bulk value ∼0.51) clearly affirm the negligible amount of APBs in the high oxygen partial pressure deposited thin films.

POLARIZED LINE FORMATION WITH LOWER-LEVEL POLARIZATION AND PARTIAL FREQUENCY REDISTRIBUTION

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

Supriya, H. D.; Sampoorna, M.; Nagendra, K. N.

2016-09-10

In the well-established theories of polarized line formation with partial frequency redistribution (PRD) for a two-level and two-term atom, it is generally assumed that the lower level of the scattering transition is unpolarized. However, the existence of unexplained spectral features in some lines of the Second Solar Spectrum points toward a need to relax this assumption. There exists a density matrix theory that accounts for the polarization of all the atomic levels, but it is based on the flat-spectrum approximation (corresponding to complete frequency redistribution). In the present paper we propose a numerical algorithm to solve the problem of polarizedmore » line formation in magnetized media, which includes both the effects of PRD and the lower level polarization (LLP) for a two-level atom. First we derive a collisionless redistribution matrix that includes the combined effects of the PRD and the LLP. We then solve the relevant transfer equation using a two-stage approach. For illustration purposes, we consider two case studies in the non-magnetic regime, namely, the J {sub a} = 1, J {sub b} = 0 and J {sub a} = J {sub b} = 1, where J {sub a} and J {sub b} represent the total angular momentum quantum numbers of the lower and upper states, respectively. Our studies show that the effects of LLP are significant only in the line core. This leads us to propose a simplified numerical approach to solve the concerned radiative transfer problem.« less

Average characteristics of partially coherent electromagnetic beams.

PubMed

Seshadri, S R

2000-04-01

Average characteristics of partially coherent electromagnetic beams are treated with the paraxial approximation. Azimuthally or radially polarized, azimuthally symmetric beams and linearly polarized dipolar beams are used as examples. The change in the mean squared width of the beam from its value at the location of the beam waist is found to be proportional to the square of the distance in the propagation direction. The proportionality constant is obtained in terms of the cross-spectral density as well as its spatial spectrum. The use of the cross-spectral density has advantages over the use of its spatial spectrum.

Macular auto-fluorescence is a follow-up parameter for cystoids macular edema.

PubMed

Zhang, XinYuan; Gong, XiaoHong; Wang, YanHong; Wang, NingLi

2015-08-01

This study aimed to evaluate if macular autofluorescence (MAF) is a valuable, non-invasive follow-up parameter for cystoid macular edema. A total of 71 eyes (71 cases) with cystoid macular edema (CME) were included in the study. Macular pigment (MP) was evaluated using HRA2 (infrared) IF and FA models. The density of MP was graded into three categories: without, partial, and normal amount of MP. A comparison was made between the baseline (before the first administration) level and at the fourth month, following three consecutive intravitreal lucentis injections every month. The morphology and distribution of MAF, and the density and distribution of MP were regarded as the main outcome measures. At the baseline visit, all eyes with CME had petaloid/irregular-shaped MAF in the macular area (100%). No MAF was detected in the control eyes (0). There was significant difference in MAF between the CME and normal groups (P=0.000). At the fourth monthly visit, normal levels of MP density without MAF was detected in 68 eyes (95.8%) with the best corrected spectacular visual acuity increasing to at least 1 line accordingly. We conclude that macular MAF can be used as a follow-up parameter for patients with CME. MP and MAF can indirectly reflect the fovea cone function.

Development of new experimental platform 'MARS'-Multiple Artificial-gravity Research System-to elucidate the impacts of micro/partial gravity on mice.

PubMed

Shiba, Dai; Mizuno, Hiroyasu; Yumoto, Akane; Shimomura, Michihiko; Kobayashi, Hiroe; Morita, Hironobu; Shimbo, Miki; Hamada, Michito; Kudo, Takashi; Shinohara, Masahiro; Asahara, Hiroshi; Shirakawa, Masaki; Takahashi, Satoru

2017-09-07

This Japan Aerospace Exploration Agency project focused on elucidating the impacts of partial gravity (partial g) and microgravity (μg) on mice using newly developed mouse habitat cage units (HCU) that can be installed in the Centrifuge-equipped Biological Experiment Facility in the International Space Station. In the first mission, 12 C57BL/6 J male mice were housed under μg or artificial earth-gravity (1 g). Mouse activity was monitored daily via downlinked videos; μg mice floated inside the HCU, whereas artificial 1 g mice were on their feet on the floor. After 35 days of habitation, all mice were returned to the Earth and processed. Significant decreases were evident in femur bone density and the soleus/gastrocnemius muscle weights of μg mice, whereas artificial 1 g mice maintained the same bone density and muscle weight as mice in the ground control experiment, in which housing conditions in the flight experiment were replicated. These data indicate that these changes were particularly because of gravity. They also present the first evidence that the addition of gravity can prevent decreases in bone density and muscle mass, and that the new platform 'MARS' may provide novel insights on the molecular-mechanisms regulating biological processes controlled by partial g/μg.

An evaluation of the partial reflection technique and results from the winter 1971 - 1972 D region

NASA Technical Reports Server (NTRS)

Dasilva, L. C.; Bowhill, S. A.

1974-01-01

Fundamental physical and chemical processes, and measurement techniques on the D region are reviewed. Design considerations about a partial-reflection system are made, and the main characteristics of the partial-reflection system at the University of Illinois are presented. The nature of the partial reflections is discussed, particularly reflections produced by gradients in electron density and by random fluctuations in a locally homogeneous random medium. Possible reasons for disagreement between partial reflections and rocket measurements are discussed. Some suggestions are made to improve partial-reflection data reduction, including the use of only maximums of the reflections and deconvolution of the data. The results of partial-reflection measurements at Wallops Island, Virginia during the 1971-1972 winter are presented and compared to rocket measurements.

A density functional study of atomic hydrogen and oxygen chemisorption on the relaxed (0001) surface of double hexagonal close packed americium

NASA Astrophysics Data System (ADS)

Dholabhai, P. P.; Atta-Fynn, R.; Ray, A. K.

2008-02-01

Ab initio total energy calculations within the framework of density functional theory have been performed for atomic hydrogen and oxygen chemisorption on the (0001) surface of double hexagonal packed americium using a full-potential all-electron linearized augmented plane wave plus local orbitals method. Chemisorption energies were optimized with respect to the distance of the adatom from the relaxed surface for three adsorption sites, namely top, bridge, and hollow hcp sites, the adlayer structure corresponding to coverage of a 0.25 monolayer in all cases. Chemisorption energies were computed at the scalar-relativistic level (no spin-orbit coupling NSOC) and at the fully relativistic level (with spin-orbit coupling SOC). The two-fold bridge adsorption site was found to be the most stable site for O at both the NSOC and SOC theoretical levels with chemisorption energies of 8.204 eV and 8.368 eV respectively, while the three-fold hollow hcp adsorption site was found to be the most stable site for H with chemisorption energies of 3.136 eV at the NSOC level and 3.217 eV at the SOC level. The respective distances of the H and O adatoms from the surface were found to be 1.196 Åand 1.164 Å. Overall our calculations indicate that chemisorption energies in cases with SOC are slightly more stable than the cases with NSOC in the 0.049 0.238 eV range. The work functions and net magnetic moments respectively increased and decreased in all cases compared with the corresponding quantities of bare dhcp Am (0001) surface. The partial charges inside the muffin-tins, difference charge density distributions, and the local density of states have been used to analyze the Am-adatom bond interactions in detail. The implications of chemisorption on Am 5f electron localization-delocalization are also discussed.

Seeing Eye to Eye: Predicting Teacher-Student Agreement on Classroom Social Networks

PubMed Central

Neal, Jennifer Watling; Cappella, Elise; Wagner, Caroline; Atkins, Marc S.

2010-01-01

This study examines the association between classroom characteristics and teacher-student agreement in perceptions of students’ classroom peer networks. Social network, peer nomination, and observational data were collected from a sample of second through fourth grade teachers (N=33) and students (N=669) in 33 classrooms across five high poverty urban schools. Results demonstrate that variation in teacher-student agreement on the structure of students’ peer networks can be explained, in part, by developmental factors and classroom characteristics. Developmental increases in network density partially mediated the positive relationship between grade level and teacher-student agreement. Larger class sizes and higher levels of normative aggressive behavior resulted in lower levels of teacher-student agreement. Teachers’ levels of classroom organization had mixed influences, with behavior management negatively predicting agreement, and productivity positively predicting agreement. These results underscore the importance of the classroom context in shaping teacher and student perceptions of peer networks. PMID:21666768

PROM7: 1D modeler of solar filaments or prominences

NASA Astrophysics Data System (ADS)

Gouttebroze, P.

2018-05-01

PROM7 is an update of PROM4 (ascl:1306.004) and computes simple models of solar prominences and filaments using Partial Radiative Distribution (PRD). The models consist of plane-parallel slabs standing vertically above the solar surface. Each model is defined by 5 parameters: temperature, density, geometrical thickness, microturbulent velocity and height above the solar surface. It solves the equations of radiative transfer, statistical equilibrium, ionization and pressure equilibria, and computes electron and hydrogen level population and hydrogen line profiles. Moreover, the code treats calcium atom which is reduced to 3 ionization states (Ca I, Ca II, CA III). Ca II ion has 5 levels which are useful for computing 2 resonance lines (H and K) and infrared triplet (to 8500 A).

Network signatures of nuclear and cytoplasmic density alterations in a model of pre and postmetastatic colorectal cancer

NASA Astrophysics Data System (ADS)

Damania, Dhwanil; Subramanian, Hariharan; Backman, Vadim; Anderson, Eric C.; Wong, Melissa H.; McCarty, Owen J. T.; Phillips, Kevin G.

2014-01-01

Cells contributing to the pathogenesis of cancer possess cytoplasmic and nuclear structural alterations that accompany their aberrant genetic, epigenetic, and molecular perturbations. Although it is known that architectural changes in primary and metastatic tumor cells can be quantified through variations in cellular density at the nanometer and micrometer spatial scales, the interdependent relationships among nuclear and cytoplasmic density as a function of tumorigenic potential has not been thoroughly investigated. We present a combined optical approach utilizing quantitative phase microscopy and partial wave spectroscopic microscopy to perform parallel structural characterizations of cellular architecture. Using the isogenic SW480 and SW620 cell lines as a model of pre and postmetastatic transition in colorectal cancer, we demonstrate that nuclear and cytoplasmic nanoscale disorder, micron-scale dry mass content, mean dry mass density, and shape metrics of the dry mass density histogram are uniquely correlated within and across different cellular compartments for a given cell type. The correlations of these physical parameters can be interpreted as networks whose nodal importance and level of connection independence differ according to disease stage. This work demonstrates how optically derived biophysical parameters are linked within and across different cellular compartments during the architectural orchestration of the metastatic phenotype.

Wetland use and feeding by lesser scaup during spring migration across the upper Midwest, USA

USGS Publications Warehouse

Anteau, M.J.; Afton, A.D.

2009-01-01

Low food availability and forage quality and concomitant decreased lipid reserves of lesser scaup (Aythya affinis; hereafter scaup) during spring migration in the upper Midwest may partially explain reductions in the continental population of scaup. In springs 20042005, we examined wetland use and feeding activity of scaup on 356 randomly-selected wetlands within 6 regions in Iowa, Minnesota, and North Dakota. We examined wetland characteristics that favor high scaup use in 286 of these wetlands. We found that probabilities of wetland use and feeding by scaup increased with turbidity up to 45 and 30 NTU, respectively, but then declined at higher turbidity levels. Wetland use was positively correlated with size of open-water zone and amphipod densities, but was not correlated with chironomid densities. Feeding increased with amphipod density up to 26 m-3 and then declined at higher amphipod densities; scaup seemingly forage most efficiently at amphipod densities above 26 m -3. Wetland use was higher in North Dakota than in southern Minnesota and Iowa. Our results indicate that effective wetland restoration efforts to benefit scaup require maintaining abundant populations of amphipods (generally near 26 m-3 landscape geometric mean) in wetlands with large (> 500 m diameter) open-water zones throughout the upper Midwest, but especially within Iowa and southern Minnesota.

Metalloid Aluminum Clusters with Fluorine

DTIC Science & Technology

2016-12-01

molecular dynamics, binding energy , siesta code, density of states, projected density of states 15. NUMBER OF PAGES 69 16. PRICE CODE 17. SECURITY...high energy density compared to explosives, but typically release this energy slowly via diffusion-limited combustion. There is recent interest in using...examine the cluster binding energy and electronic structure. Partial fluorine substitution in a prototypical aluminum-cyclopentadienyl cluster results

Low-Density, Aerogel-Filled Thermal-Insulation Tiles

NASA Technical Reports Server (NTRS)

Santos, Maryann; Heng, Vann; Barney, Andrea; Oka, Kris; Droege, Michael

2005-01-01

Aerogel fillings have been investigated in a continuing effort to develop low-density thermal-insulation tiles that, relative to prior such tiles, have greater dimensional stability (especially less shrinkage), equal or lower thermal conductivity, and greater strength and durability. In preparation for laboratory tests of dimensional and thermal stability, prototypes of aerogel-filled versions of recently developed low-density tiles have been fabricated by impregnating such tiles to various depths with aerogel formations ranging in density from 1.5 to 5.6 lb/ft3 (about 53 to 200 kg/cu m). Results available at the time of reporting the information for this article showed that the thermal-insulation properties of the partially or fully aerogel- impregnated tiles were equivalent or superior to those of the corresponding non-impregnated tiles and that the partially impregnated tiles exhibited minimal (<1.5 percent) shrinkage after multiple exposures at a temperature of 2,300 F (1,260 C). Latest developments have shown that tiles containing aerogels at the higher end of the density range are stable after multiple exposures at the said temperature.

The effects of sea level and palaeotopography on lithofacies distribution and geometries in heterozoan carbonates, south-eastern Spain

USGS Publications Warehouse

Johnson, C.L.; Franseen, E.K.; Goldstein, R.H.

2005-01-01

This study utilized three-dimensional exposures to evaluate how sea-level position and palaeotopography control the facies and geometries of heterozoan carbonates. Heterozoan carbonates were deposited on top of a Neogene volcanic substrate characterized by palaeotopographic highs, palaeovalleys, and straits that were formed by subaerial erosion, possibly original volcanic topography, and faults prior to carbonate deposition. The depositional sequence that is the focus of this study (DS1B) consists of 7-10 fining upward cycles that developed in response to relative sea-level fluctuations. A complete cycle has a basal erosion surface overlain by deposits of debrisflows and high-density turbidity currents, which formed during relative sea-level fall. Overlying tractive deposits most likely formed during the lowest relative position of sea level. Overlying these are debrites grading upward to high-density turbidites and low-density turbidites that formed during relative sea-level rise. The tops of the cycles consist of hemipelagic deposits that formed during the highest relative position of sea level. The cycles fine upward because upslope carbonate production decreased as relative sea level rose due to less surface area available for shallow-water carbonate production and partial drowning of substrates. The cycles are dominated by two end-member types of facies associations and stratal geometries that formed in response to fluctuating sea-level position over variable substrate palaeotopography. One end-member is termed 'flank flow cycle' because this type of cycle indicates dominant sediment transport down the flanks of palaeovalleys. Those cycles drape the substrate, have more debrites, high-density turbidites and erosion on palaeovalley flanks, and in general, the lithofacies fine down the palaeovalley flanks into the palaeovalley axes. The second end-member is termed 'axial flow cycle' because it indicates a dominance of sediment transport down the axes of palaeovalleys. Those cycles are characterized by debrites and high-density turbidites in palaeovalley axes, and lap out of strata against the flanks of palaeovalleys. Where and when an axial flow cycle or flank flow cycle developed appears to be related to the intersection of sea level with areas of gentle or steep substrate slopes, during an overall relative rise in sea level. Results from this study provide a model for similar systems that must combine carbonate principles for sediment production, palaeotopographic controls, and physical principles of sediment remobilization into deep water. ?? 2005 International Association of Sedimentologists.

Transformation behavior of Ni-Mn-Ga in the low-temperature limit.

PubMed

Pérez-Landazábal, J I; Recarte, V; Sánchez-Alarcos, V; Chernenko, V A; Barandiarán, J M; Lázpita, P; Rodriguez Fernández, J; Righi, L

2012-07-11

The magnetic, magnetocaloric and thermal characteristics have been studied in a Ni(50.3)Mn(20.8)Ga(27.6)V(1.3) ferromagnetic shape memory alloy (FSMA) transforming martensitically at around 40 K. The alloy shows first a transformation from austenite to an intermediate phase and then a partial transformation to an orthorhombic martensite, all the phases being ferromagnetically ordered. The thermomagnetization dependences enabled observation of the magnetocaloric effect in the vicinity of the martensitic transformation (MT). The Debye temperature and the density of states at the Fermi level are equal to θ(D) = (276 ± 4) K and 1.3 states/atom eV , respectively, and scarcely dependent on the magnetic field. The MT exhibited by Ni-Mn-Ga FSMAs at very low temperatures is distinctive in the sense that it is accompanied by a hardly detectable entropy change as a sign of a small driving force. The enhanced stability of the cubic phase and the low driving force of the MT stem from the reduced density of states near the Fermi level.

Observation of the origin of d0 magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques

NASA Astrophysics Data System (ADS)

Singh, Shashi B.; Wang, Yu-Fu; Shao, Yu-Cheng; Lai, Hsuan-Yu; Hsieh, Shang-Hsien; Limaye, Mukta V.; Chuang, Chen-Hao; Hsueh, Hung-Chung; Wang, Hsaiotsu; Chiou, Jau-Wern; Tsai, Hung-Ming; Pao, Chih-Wen; Chen, Chia-Hao; Lin, Hong-Ji; Lee, Jyh-Fu; Wu, Chun-Te; Wu, Jih-Jen; Pong, Way-Faung; Ohigashi, Takuji; Kosugi, Nobuhiro; Wang, Jian; Zhou, Jigang; Regier, Tom; Sham, Tsun-Kong

2014-07-01

Efforts have been made to elucidate the origin of d0 magnetism in ZnO nanocactuses (NCs) and nanowires (NWs) using X-ray-based microscopic and spectroscopic techniques. The photoluminescence and O K-edge and Zn L3,2-edge X-ray-excited optical luminescence spectra showed that ZnO NCs contain more defects than NWs do and that in ZnO NCs, more defects are present at the O sites than at the Zn sites. Specifically, the results of O K-edge scanning transmission X-ray microscopy (STXM) and the corresponding X-ray-absorption near-edge structure (XANES) spectroscopy demonstrated that the impurity (non-stoichiometric) region in ZnO NCs contains a greater defect population than the thick region. The intensity of O K-edge STXM-XANES in the impurity region is more predominant in ZnO NCs than in NWs. The increase in the unoccupied (occupied) density of states at/above (at/below) the conduction-band minimum (valence-band maximum) or the Fermi level is related to the population of defects at the O sites, as revealed by comparing the ZnO NCs to the NWs. The results of O K-edge and Zn L3,2-edge X-ray magnetic circular dichroism demonstrated that the origin of magnetization is attributable to the O 2p orbitals rather than the Zn d orbitals. Further, the local density approximation (LDA) + U verified that vacancies in the form of dangling or unpaired 2p states (due to Zn vacancies) induced a significant local spin moment in the nearest-neighboring O atoms to the defect center, which was determined from the uneven local spin density by analyzing the partial density of states of O 2p in ZnO.Efforts have been made to elucidate the origin of d0 magnetism in ZnO nanocactuses (NCs) and nanowires (NWs) using X-ray-based microscopic and spectroscopic techniques. The photoluminescence and O K-edge and Zn L3,2-edge X-ray-excited optical luminescence spectra showed that ZnO NCs contain more defects than NWs do and that in ZnO NCs, more defects are present at the O sites than at the Zn sites. Specifically, the results of O K-edge scanning transmission X-ray microscopy (STXM) and the corresponding X-ray-absorption near-edge structure (XANES) spectroscopy demonstrated that the impurity (non-stoichiometric) region in ZnO NCs contains a greater defect population than the thick region. The intensity of O K-edge STXM-XANES in the impurity region is more predominant in ZnO NCs than in NWs. The increase in the unoccupied (occupied) density of states at/above (at/below) the conduction-band minimum (valence-band maximum) or the Fermi level is related to the population of defects at the O sites, as revealed by comparing the ZnO NCs to the NWs. The results of O K-edge and Zn L3,2-edge X-ray magnetic circular dichroism demonstrated that the origin of magnetization is attributable to the O 2p orbitals rather than the Zn d orbitals. Further, the local density approximation (LDA) + U verified that vacancies in the form of dangling or unpaired 2p states (due to Zn vacancies) induced a significant local spin moment in the nearest-neighboring O atoms to the defect center, which was determined from the uneven local spin density by analyzing the partial density of states of O 2p in ZnO. Electronic supplementary information (ESI) available: Scanning photoelectron microscopy (SPEM) results of ZnO NCs and NWs. Computational details and calculated total and partial density of states (PDOS) of bulk wurtzite ZnO with oxygen anion vacancies (VO). See DOI: 10.1039/c4nr01961j

Comparison of different models for predicting soil bulk density. Case study - Slovakian agricultural soils

NASA Astrophysics Data System (ADS)

Makovníková, Jarmila; Širáň, Miloš; Houšková, Beata; Pálka, Boris; Jones, Arwyn

2017-10-01

Soil bulk density is one of the main direct indicators of soil health, and is an important aspect of models for determining agroecosystem services potential. By way of applying multi-regression methods, we have created a distributed prediction of soil bulk density used subsequently for topsoil carbon stock estimation. The soil data used for this study were from the Slovakian partial monitoring system-soil database. In our work, two models of soil bulk density in an equilibrium state, with different combinations of input parameters (soil particle size distribution and soil organic carbon content in %), have been created, and subsequently validated using a data set from 15 principal sampling sites of Slovakian partial monitoring system-soil, that were different from those used to generate the bulk density equations. We have made a comparison of measured bulk density data and data calculated by the pedotransfer equations against soil bulk density calculated according to equations recommended by Joint Research Centre Sustainable Resources for Europe. The differences between measured soil bulk density and the model values vary from -0.144 to 0.135 g cm-3 in the verification data set. Furthermore, all models based on pedotransfer functions give moderately lower values. The soil bulk density model was then applied to generate a first approximation of soil bulk density map for Slovakia using texture information from 17 523 sampling sites, and was subsequently utilised for topsoil organic carbon estimation.

Facilitation in Caribbean coral reefs: high densities of staghorn coral foster greater coral condition and reef fish composition.

PubMed

Huntington, Brittany E; Miller, Margaret W; Pausch, Rachel; Richter, Lee

2017-05-01

Recovery of the threatened staghorn coral (Acropora cervicornis) is posited to play a key role in Caribbean reef resilience. At four Caribbean locations (including one restored and three extant populations), we quantified characteristics of contemporary staghorn coral across increasing conspecific densities, and investigated a hypothesis of facilitation between staghorn coral and reef fishes. High staghorn densities in the Dry Tortugas exhibited significantly less partial mortality, higher branch growth, and supported greater fish abundances compared to lower densities within the same population. In contrast, partial mortality, branch growth, and fish community composition did not vary with staghorn density at the three other study locations where staghorn densities were lower overall. This suggests that density-dependent effects between the coral and fish community may only manifest at high staghorn densities. We then evaluated one facilitative mechanism for such density-dependence, whereby abundant fishes sheltering in dense staghorn aggregations deliver nutrients back to the coral, fueling faster coral growth, thereby creating more fish habitat. Indeed, dense staghorn aggregations within the Dry Tortugas exhibited significantly higher growth rates, tissue nitrogen, and zooxanthellae densities than sparse aggregations. Similarly, higher tissue nitrogen was induced in a macroalgae bioassay outplanted into the same dense and sparse aggregations, confirming greater bioavailability of nutrients at high staghorn densities. Our findings inform staghorn restoration efforts, suggesting that the most effective targets may be higher coral densities than previously thought. These coral-dense aggregations may reap the benefits of positive facilitation between the staghorn and fish community, favoring the growth and survivorship of this threatened species.

Partially coherent axiconic surface plasmon polariton fields

NASA Astrophysics Data System (ADS)

Chen, Yahong; Norrman, Andreas; Ponomarenko, Sergey A.; Friberg, Ari T.

2018-04-01

We introduce a class of structured polychromatic surface electromagnetic fields, reminiscent of conventional optical axicon fields, through a judicious superposition of partially correlated surface plasmon polaritons. We show that such partially coherent axiconic surface plasmon polariton fields are structurally stable and statistically highly versatile with regard to spectral density, polarization state, energy flow, and degree of coherence. These fields can be created by plasmon coherence engineering and may prove instrumental broadly in surface physics and in various nanophotonics applications.

DENSITY-DEPENDENT FLOW IN ONE-DIMENSIONAL VARIABLY-SATURATED MEDIA

EPA Science Inventory

A one-dimensional finite element is developed to simulate density-dependent flow of saltwater in variably saturated media. The flow and solute equations were solved in a coupled mode (iterative), in a partially coupled mode (non-iterative), and in a completely decoupled mode. P...

Ecosystem carbon density and allocation across a chronosequence of longleaf pine forests

Treesearch

Lisa J. Samuelson; Thomas A. Stokes; John R. Butnor; Kurt H. Johnsen; Carlos A. Gonzalez-Benecke; Timothy A. Martin; Wendell P. Cropper; Pete H. Anderson; Michael R. Ramirez; John C. Lewis

2017-01-01

Forests can partially offset greenhouse gas emissions and contribute to climate change mitigation, mainly through increases in live biomass. We quantified carbon (C) density in 20 managed longleaf pine (Pinus palustris Mill.) forests ranging in age from 5...

Unsteady density-current equations for highly curved terrain

NASA Technical Reports Server (NTRS)

Sivakumaran, N. S.; Dressler, R. F.

1989-01-01

New nonlinear partial differential equations containing terrain curvature and its rate of change are derived that describe the flow of an atmospheric density current. Unlike the classical hydraulic-type equations for density currents, the new equations are valid for two-dimensional, gradually varied flow over highly curved terrain, hence suitable for computing unsteady (or steady) flows over arbitrary mountain/valley profiles. The model assumes the atmosphere above the density current exerts a known arbitrary variable pressure upon the unknown interface. Later this is specialized to the varying hydrostatic pressure of the atmosphere above. The new equations yield the variable velocity distribution, the interface position, and the pressure distribution that contains a centrifugal component, often significantly larger than its hydrostatic component. These partial differential equations are hyperbolic, and the characteristic equations and characteristic directions are derived. Using these to form a characteristic mesh, a hypothetical unsteady curved-flow problem is calculated, not based upon observed data, merely as an example to illustrate the simplicity of their application to unsteady flows over mountains.

Computing rates of Markov models of voltage-gated ion channels by inverting partial differential equations governing the probability density functions of the conducting and non-conducting states.

PubMed

Tveito, Aslak; Lines, Glenn T; Edwards, Andrew G; McCulloch, Andrew

2016-07-01

Markov models are ubiquitously used to represent the function of single ion channels. However, solving the inverse problem to construct a Markov model of single channel dynamics from bilayer or patch-clamp recordings remains challenging, particularly for channels involving complex gating processes. Methods for solving the inverse problem are generally based on data from voltage clamp measurements. Here, we describe an alternative approach to this problem based on measurements of voltage traces. The voltage traces define probability density functions of the functional states of an ion channel. These probability density functions can also be computed by solving a deterministic system of partial differential equations. The inversion is based on tuning the rates of the Markov models used in the deterministic system of partial differential equations such that the solution mimics the properties of the probability density function gathered from (pseudo) experimental data as well as possible. The optimization is done by defining a cost function to measure the difference between the deterministic solution and the solution based on experimental data. By evoking the properties of this function, it is possible to infer whether the rates of the Markov model are identifiable by our method. We present applications to Markov model well-known from the literature. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Density Contrast Sedimentation Velocity for the Determination of Protein Partial-Specific Volumes

PubMed Central

Brown, Patrick H.; Balbo, Andrea; Zhao, Huaying; Ebel, Christine; Schuck, Peter

2011-01-01

The partial-specific volume of proteins is an important thermodynamic parameter required for the interpretation of data in several biophysical disciplines. Building on recent advances in the use of density variation sedimentation velocity analytical ultracentrifugation for the determination of macromolecular partial-specific volumes, we have explored a direct global modeling approach describing the sedimentation boundaries in different solvents with a joint differential sedimentation coefficient distribution. This takes full advantage of the influence of different macromolecular buoyancy on both the spread and the velocity of the sedimentation boundary. It should lend itself well to the study of interacting macromolecules and/or heterogeneous samples in microgram quantities. Model applications to three protein samples studied in either H2O, or isotopically enriched H2 18O mixtures, indicate that partial-specific volumes can be determined with a statistical precision of better than 0.5%, provided signal/noise ratios of 50–100 can be achieved in the measurement of the macromolecular sedimentation velocity profiles. The approach is implemented in the global modeling software SEDPHAT. PMID:22028836

Densities, Ultrasonic Speeds, and Excess Properties of Binary Mixtures of Diethylene Glycol with 1-Butanol, 2-Butanol, and 1,4-Butanediol at Different Temperatures

NASA Astrophysics Data System (ADS)

Ali, Anwar; Ansari, Sana; Uzair, Sahar; Tasneem, Shadma; Nabi, Firdosa

2015-11-01

Densities ρ and ultrasonic speeds u for pure diethylene glycol, 1-butanol, 2-butanol, and 1,4-butanediol and for their binary mixtures over the entire composition range were measured at 298.15 K, 303.15 K, 308.15 K, and 313.15 K. Using these data, the excess molar volumes, VE_m, deviations in isentropic compressibilities, {\\varDelta }ks, apparent molar volumes, V_{φi} , partial molar volumes, overline{V}_{m,i} , and excess partial molar volumes, overline{V}_{m,i}^E , have been calculated over the entire composition range, and also the excess partial molar volumes of the components at infinite dilution, overline{V}_{m,i}^{E,infty } have been calculated. The excess functions have been correlated using the Redlich-Kister equation at different temperatures. The variations of these derived parameters with composition and temperature are presented graphically.

Fast Computation of Solvation Free Energies with Molecular Density Functional Theory: Thermodynamic-Ensemble Partial Molar Volume Corrections.

PubMed

Sergiievskyi, Volodymyr P; Jeanmairet, Guillaume; Levesque, Maximilien; Borgis, Daniel

2014-06-05

Molecular density functional theory (MDFT) offers an efficient implicit-solvent method to estimate molecule solvation free-energies, whereas conserving a fully molecular representation of the solvent. Even within a second-order approximation for the free-energy functional, the so-called homogeneous reference fluid approximation, we show that the hydration free-energies computed for a data set of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by 2-3 orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canonical to the isobaric-isotherm ensemble that is pertinent to experiments. We show that this correction can be extended to 3D-RISM calculations, giving a sound theoretical justification to empirical partial molar volume corrections that have been proposed recently.

Tunable electronic properties of partially edge-hydrogenated armchair boron-nitrogen-carbon nanoribbons.

PubMed

Alaal, Naresh; Medhekar, Nikhil; Shukla, Alok

2018-04-18

We employ a first-principles calculations based density-functional-theory (DFT) approach to study the electronic properties of partially and fully edge-hydrogenated armchair boron-nitrogen-carbon (BNC) nanoribbons (ABNCNRs), with widths between 0.85 nm to 2.3 nm. Due to the partial passivation of edges, the electrons, which do not participate in the bonding, form new energy states located near the Fermi-level. Because of these additional bands, some ABNCNRs exhibit metallic behavior, which is quite uncommon in armchair nanoribbons. Our calculations reveal that metallic behavior is observed for the following passivation patterns: (i) when the B atom from one edge and the N atom from another edge are unpassivated. (ii) when the N atoms from both the edges are unpassivated. (iii) when the C atom from one edge and the N atom from another edge are unpassivated. Furthermore, spin-polarization is also observed for certain passivation schemes, which is also quite uncommon for armchair nanoribbons. Thus, our results suggest that the ABNCNRs exhibit a wide range of electronic and magnetic properties in that the fully edge-hydrogenated ABNCNRs are direct band gap semiconductors, while the partially edge-hydrogenated ones are either semiconducting, or metallic, while simultaneously exhibiting spin polarization, based on the nature of passivation. We also find that the ribbons with larger widths are more stable as compared to the narrower ones.

Propagation of partially coherent Lorentz-Gauss vortex beam through oceanic turbulence.

PubMed

Liu, Dajun; Yin, Hongming; Wang, Guiqiu; Wang, Yaochuan

2017-11-01

The partially coherent Lorentz-Gauss vortex beam generated by a Schell-model source has been introduced. Based on the extended Huygens-Fresnel principle, the cross-spectral density function of a partially coherent Lorentz-Gauss vortex beam propagating in oceanic turbulence is derived. The influences of coherence length, topological charge M, and oceanic turbulence on the spreading properties and position of the coherence vortex for a partially coherent Lorentz-Gauss vortex beam are analyzed in detail. The results show that a partially coherent Lorentz-Gauss vortex beam propagating in stronger oceanic turbulence will evolve into a Gaussian-like beam more rapidly as the propagation distance increases, and the number of coherent vortices will change.

Midlatitude sporadic-E layers

NASA Technical Reports Server (NTRS)

Miller, K. L.; Smith, L. G.

1976-01-01

The partially transparent echo from midlatitude sporadic E layers was recorded by ionosondes between the blanketing frequency and the maximum frequency. The theory that the midlatitude sporadic E layers are not uniform in the horizontal plane but contain localized regions of high electron density was evaluated using data obtained by incoherent scatter radar and found to provide a satisfactory explanation. The main features of midlatitude sporadic E layers are consistent with the convergence of metallic ions as described by the wind shear theory applied to gravity waves and tides. The interference of gravity waves with other gravity waves and tides can be recognized in the altitudes of occurrence and the structure of the layers. Small scale horizontal irregularities are attributed in some cases to critical level effects and in others to fluid instabilities. The convergence of a meteor trail can, under some circumstances, account for localized enhancement of the electron density in the layer.

A mathematical model of algae growth in a pelagic-benthic coupled shallow aquatic ecosystem.

PubMed

Zhang, Jimin; Shi, Junping; Chang, Xiaoyuan

2018-04-01

A coupled system of ordinary differential equations and partial differential equations is proposed to describe the interaction of pelagic algae, benthic algae and one essential nutrient in an oligotrophic shallow aquatic ecosystem with ample supply of light. The existence and uniqueness of non-negative steady states are completely determined for all possible parameter range, and these results characterize sharp threshold conditions for the regime shift from extinction to coexistence of pelagic and benthic algae. The influence of environmental parameters on algal biomass density is also considered, which is an important indicator of algal blooms. Our studies suggest that the nutrient recycling from loss of algal biomass may be an important factor in the algal blooms process; and the presence of benthic algae may limit the pelagic algal biomass density as they consume common resources even if the sediment nutrient level is high.

Measurement of Vibrated Bulk Density of Coke Particle Blends Using Image Texture Analysis

NASA Astrophysics Data System (ADS)

Azari, Kamran; Bogoya-Forero, Wilinthon; Duchesne, Carl; Tessier, Jayson

2017-09-01

A rapid and nondestructive machine vision sensor was developed for predicting the vibrated bulk density (VBD) of petroleum coke particles based on image texture analysis. It could be used for making corrective adjustments to a paste plant operation to reduce green anode variability (e.g., changes in binder demand). Wavelet texture analysis (WTA) and gray level co-occurrence matrix (GLCM) algorithms were used jointly for extracting the surface textural features of coke aggregates from images. These were correlated with the VBD using partial least-squares (PLS) regression. Coke samples of several sizes and from different sources were used to test the sensor. Variations in the coke surface texture introduced by coke size and source allowed for making good predictions of the VBD of individual coke samples and mixtures of them (blends involving two sources and different sizes). Promising results were also obtained for coke blends collected from an industrial-baked carbon anode manufacturer.

Impacts of blending on dilution of negatively buoyant brine discharge in a shallow tidal sea.

PubMed

Kämpf, Jochen

2009-07-01

A fine-resolution three-dimensional hydrodynamic model is applied to study the dilution of desalination brine discharged into a tidal sea. Based on given inflow rate and salinity excess of discharge brine, this study explores variations in mid-field dilutions when other low-salinity wastewater is added to the discharge. Findings reveal that this blending leads to a decrease in dilution in the mixing zone and therefore to higher levels of pollutants in this zone, while, on the other hand, the mixing zone occupies a smaller area. The reason is that the discharge of brine creates a density-driven flow that operates to partially remove effluent from the discharge location. This removal is less efficient for the decrease in density excess of the discharge. Hence, in an ambient sea of moderate mixing, blending can be expected to increase the risk of marine pollution in the mixing zone.

Markedly accelerated catabolism of apolipoprotein A-II (ApoA-II) and high density lipoproteins containing ApoA-II in classic lecithin: cholesterol acyltransferase deficiency and fish-eye disease.

PubMed Central

Rader, D J; Ikewaki, K; Duverger, N; Schmidt, H; Pritchard, H; Frohlich, J; Clerc, M; Dumon, M F; Fairwell, T; Zech, L

1994-01-01

Classic (complete) lecithin:cholesterol acyltransferase (LCAT) deficiency and Fish-eye disease (partial LCAT deficiency) are genetic syndromes associated with markedly decreased plasma levels of high density lipoprotein (HDL) cholesterol but not with an increased risk of atherosclerotic cardiovascular disease. We investigated the metabolism of the HDL apolipoproteins (apo) apoA-I and apoA-II in a total of five patients with LCAT deficiency, one with classic LCAT deficiency and four with Fish-eye disease. Plasma levels of apoA-II were decreased to a proportionately greater extent (23% of normal) than apoA-I (30% of normal). In addition, plasma concentrations of HDL particles containing both apoA-I and apoA-II (LpA-I:A-II) were much lower (18% of normal) than those of particles containing only apoA-I (LpA-I) (51% of normal). The metabolic basis for the low levels of apoA-II and LpA-I:A-II was investigated in all five patients using both exogenous radiotracer and endogenous stable isotope labeling techniques. The mean plasma residence time of apoA-I was decreased at 2.08 +/- 0.27 d (controls 4.74 +/- 0.65 days); however, the residence time of apoA-II was even shorter at 1.66 +/- 0.24 d (controls 5.25 +/- 0.61 d). In addition, the catabolism of apoA-I in LpA-I:A-II was substantially faster than that of apoA-I in LpA-I. In summary, genetic syndromes of either complete or partial LCAT deficiency result in low levels of HDL through preferential hypercatabolism of apoA-II and HDL particles containing apoA-II. Because LpA-I has been proposed to be more protective than LpA-I:A-II against atherosclerosis, this selective effect on the metabolism of LpA-I:A-II may provide a potential explanation why patients with classic LCAT deficiency and Fish-eye disease are not at increased risk for premature atherosclerosis despite markedly decreased levels of HDL cholesterol and apoA-I. PMID:8282802

LANDSAT-D data format control book. Volume 6, appendix A: Partially processed thematic mapper High Density Tape (HDT-AT)

NASA Technical Reports Server (NTRS)

Jai, A.

1982-01-01

One of the outputs of the data management system being developed to provide a variety of standard image products from the thematic mapper and the multispectral band scanners on LANDSAT 4, is the partially processed TM data (radiometric corrections applied and geometric correction matrices for two projections appended) which is recorded on a 28-track high density tape. Specifications are presented for the format of the recorded data as well as for the time code and the major and minor frames of the tape. Major frame types, formats, and field definitions are included.

An ion interaction model for the volumetric properties of natural waters: Density of the solution and partial molal volumes of electrolytes to high concentrations at 25°C

NASA Astrophysics Data System (ADS)

Monnin, Christophe

1989-06-01

Literature density data for binary and common ion ternary solutions in the Na-K-Ca-Mg-Cl-SO 4-HCO 3-CO3-H 2O system at 25°C have been analysed with Pitzer's ion interaction model, which provides an adequate representation of the experimental data for binary and common ion ternary solutions up to high concentration. This analysis yields Pitzer's interaction parameters for the apparent and partial molal volumes, which are the first derivatives with respect to pressure of the interaction parameters for the free energy. From this information, densities of natural waters as well as partial molal volumes of their solutes can be predicted with good accuracy, as shown by several comparisons of calculated and measured values. It is shown that V¯MX - V¯0mx, the excess partial molal volume of the salt MX, depends more on the type of salt than on the electrolyte itself and that it increases with the charges of the salt components. The influence of concentration and composition on the variation of activity coefficients with pressure and on the partial molal volumes of the salts is discussed, using as an example the partial molal volume of CaSO 4(aq) in solutions of various compositions. The increase of V¯CaSO 4, with ionic strength is very large but is not very different for a NaCl-dominated natural water like the Red Sea lower brine than for a simple NaCl solution. Although the variation of activity coefficients with pressure is usually ignored for moderate pressures, like those found in hydrothermal environments, the present example shows that it can be as large as 30% for a 2-2 salt for a pressure increase from 1 to 500 bars at high ionic strength.

Time multiplexing for increased FOV and resolution in virtual reality

NASA Astrophysics Data System (ADS)

Miñano, Juan C.; Benitez, Pablo; Grabovičkić, Dejan; Zamora, Pablo; Buljan, Marina; Narasimhan, Bharathwaj

2017-06-01

We introduce a time multiplexing strategy to increase the total pixel count of the virtual image seen in a VR headset. This translates into an improvement of the pixel density or the Field of View FOV (or both) A given virtual image is displayed by generating a succession of partial real images, each representing part of the virtual image and together representing the virtual image. Each partial real image uses the full set of physical pixels available in the display. The partial real images are successively formed and combine spatially and temporally to form a virtual image viewable from the eye position. Partial real images are imaged through different optical channels depending of its time slot. Shutters or other schemes are used to avoid that a partial real image be imaged through the wrong optical channels or at the wrong time slot. This time multiplexing strategy needs real images be shown at high frame rates (>120fps). Available display and shutters technologies are discussed. Several optical designs for achieving this time multiplexing scheme in a compact format are shown. This time multiplexing scheme allows increasing the resolution/FOV of the virtual image not only by increasing the physical pixel density but also by decreasing the pixels switching time, a feature that may be simpler to achieve in certain circumstances.

Experimental Cancer Cachexia Changes Neuron Numbers and Peptide Levels in the Intestine: Partial Protective Effects after Dietary Supplementation with L-Glutamine

PubMed Central

Vicentini, Geraldo E.; Fracaro, Luciane; de Souza, Sara R. G.; Martins, Heber A.; Guarnier, Flávia A.; Zanoni, Jacqueline N.

2016-01-01

Gastrointestinal dysmotility frequently occurs in cancer cachexia and may result from damage to enteric innervation caused by oxidative stress, especially due to glutathione depletion. We assessed the effect of dietary supplementation with 20 g/kg l-glutamine (a glutathione precursor) on the intrinsic innervation of the enteric nervous system in healthy and Walker 256 tumor-bearing Wistar rats during the development of experimental cachexia (14 days), in comparison with non-supplemented rats, by using immunohistochemical methods and Western blotting. The total neural population and cholinergic subpopulation densities in the myenteric plexus, as well as the total population and VIPergic subpopulation in the submucosal plexus of the jejunum and ileum, were reduced in cachectic rats, resulting in adaptive morphometric alterations and an increase in vasoactive intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP) expression, suggesting a neuroplastic response. l-glutamine supplementation prevented decrease in myenteric neuronal density in the ileum, morphometric alterations in the neurons and nerve fibers (in both the plexuses of the jejunum and ileum), and the overexpression of VIP and CGRP. Cancer cachexia severely affected the intrinsic innervation of the jejunum and ileum to various degrees and this injury seems to be associated with adaptive neural plasticity. l-glutamine supplementation presented partial protective effects on the enteric innervation against cancer cachexia, possibly by attenuating oxidative stress. PMID:27635657

Experimental Cancer Cachexia Changes Neuron Numbers and Peptide Levels in the Intestine: Partial Protective Effects after Dietary Supplementation with L-Glutamine.

PubMed

Vicentini, Geraldo E; Fracaro, Luciane; de Souza, Sara R G; Martins, Heber A; Guarnier, Flávia A; Zanoni, Jacqueline N

2016-01-01

Gastrointestinal dysmotility frequently occurs in cancer cachexia and may result from damage to enteric innervation caused by oxidative stress, especially due to glutathione depletion. We assessed the effect of dietary supplementation with 20 g/kg l-glutamine (a glutathione precursor) on the intrinsic innervation of the enteric nervous system in healthy and Walker 256 tumor-bearing Wistar rats during the development of experimental cachexia (14 days), in comparison with non-supplemented rats, by using immunohistochemical methods and Western blotting. The total neural population and cholinergic subpopulation densities in the myenteric plexus, as well as the total population and VIPergic subpopulation in the submucosal plexus of the jejunum and ileum, were reduced in cachectic rats, resulting in adaptive morphometric alterations and an increase in vasoactive intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP) expression, suggesting a neuroplastic response. l-glutamine supplementation prevented decrease in myenteric neuronal density in the ileum, morphometric alterations in the neurons and nerve fibers (in both the plexuses of the jejunum and ileum), and the overexpression of VIP and CGRP. Cancer cachexia severely affected the intrinsic innervation of the jejunum and ileum to various degrees and this injury seems to be associated with adaptive neural plasticity. l-glutamine supplementation presented partial protective effects on the enteric innervation against cancer cachexia, possibly by attenuating oxidative stress.

Direct computation of thermodynamic properties of chemically reacting air with consideration to CFD

NASA Astrophysics Data System (ADS)

Iannelli, Joe

2003-10-01

This paper details a two-equation procedure to calculate exactly mass and mole fractions, pressure, temperature, specific heats, speed of sound and the thermodynamic and jacobian partial derivatives of pressure and temperature for a five-species chemically reacting equilibrium air. The procedure generates these thermodynamic properties using as independent variables either pressure and temperature or density and internal energy, for CFD applications. An original element in this procedure consists in the exact physically meaningful solution of the mass-fraction and mass-action equations. Air-equivalent molecular masses for oxygen and nitrogen are then developed to account, within a mixture of only oxygen and nitrogen, for the presence of carbon dioxide, argon and the other noble gases within atmospheric air. The mathematical formulation also introduces a versatile system non-dimensionalization that makes the procedure uniformly applicable to flows ranging from shock-tube flows with zero initial velocity to aerothermodynamic flows with supersonic/hypersonic free-stream Mach numbers. Over a temperature range of more than 10000 K and pressure and density ranges corresponding to an increase in altitude in standard atmosphere of 30000 m above sea level, the predicted distributions of mole fractions, constant-volume specific heat, and speed of sound for the model five species agree with independently published results, and all the calculated thermodynamic properties, including their partial derivatives, remain continuous, smooth, and physically meaningful.

Change In The Electronic Structure And Optical Absorption Of Cuprate Delafossites Via B-site Alloying

NASA Astrophysics Data System (ADS)

Beesley, Ramon; Panapitiya, Gihan; Lewis, James; Lewis Group Team

Delafossite oxides are a family of materials with the form ABO2 , where the A-site is a monovalent cation (Cu , Ag , Au) and the B-site is a trivalent cation (Ga , Al , In). Delafossites typically have a wide optical band gap, this band gap may be tuned by adding a second B-site element forming an AB(1- x) 1B(x)2O2 alloy. We investigate changes in the electronic structure of CuAlO2 , CuGaO2 , and CuInO2 when alloyed with CuFeO2 . Using the FIREBALL program to optimize the atomic structure, calculate the total and partial density of states, calculate the valence band edge for each alloy level, and investigate the clustering factor of the second B-site atom, it is found that alloying with Fe creates midgap states caused by Fe - O interactions. From the partial density of state, each type of atoms contribution to the change in the valence band edge can be seen. Observed changes to the materials include increased optical absorption in the visible range, and symmetry breaking because of the deformation in the crystal structure. The CuFeO2 alloying percentages range from 0-5%. We are synthesizing these alloys to experimentally verify the changes in the optical absorption spectra.

Unravelling the effects of age, period and cohort on metabolic syndrome components in a Taiwanese population using partial least squares regression

PubMed Central

2011-01-01

Background We investigate whether the changing environment caused by rapid economic growth yielded differential effects for successive Taiwanese generations on 8 components of metabolic syndrome (MetS): body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting plasma glucose (FPG), triglycerides (TG), high-density lipoprotein (HDL), Low-density lipoproteins (LDL) and uric acid (UA). Methods To assess the impact of age, birth year and year of examination on MetS components, we used partial least squares regression to analyze data collected by Mei-Jaw clinics in Taiwan in years 1996 and 2006. Confounders, such as the number of years in formal education, alcohol intake, smoking history status, and betel-nut chewing were adjusted for. Results As the age of individuals increased, the values of components generally increased except for UA. Men born after 1970 had lower FPG, lower BMI, lower DBP, lower TG, Lower LDL and greater HDL; women born after 1970 had lower BMI, lower DBP, lower TG, Lower LDL and greater HDL and UA. There is a similar pattern between the trend in levels of metabolic syndrome components against birth year of birth and economic growth in Taiwan. Conclusions We found cohort effects in some MetS components, suggesting associations between the changing environment and health outcomes in later life. This ecological association is worthy of further investigation. PMID:21619595

Molecular density functional theory of water including density-polarization coupling.

PubMed

Jeanmairet, Guillaume; Levy, Nicolas; Levesque, Maximilien; Borgis, Daniel

2016-06-22

We present a three-dimensional molecular density functional theory of water derived from first-principles that relies on the particle's density and multipolar polarization density and includes the density-polarization coupling. This brings two main benefits: (i) scalar density and vectorial multipolar polarization density fields are much more tractable and give more physical insight than the full position and orientation densities, and (ii) it includes the full density-polarization coupling of water, that is known to be non-vanishing but has never been taken into account. Furthermore, the theory requires only the partial charge distribution of a water molecule and three measurable bulk properties, namely the structure factor and the Fourier components of the longitudinal and transverse dielectric susceptibilities.

Technical Note: exploring the limit for the conversion of energy-subtracted CT number to electron density for high-atomic-number materials.

PubMed

Saito, Masatoshi; Tsukihara, Masayoshi

2014-07-01

For accurate tissue inhomogeneity correction in radiotherapy treatment planning, the authors had previously proposed a novel conversion of the energy-subtracted CT number to an electron density (ΔHU-ρe conversion), which provides a single linear relationship between ΔHU and ρe over a wide ρe range. The purpose of this study is to address the limitations of the conversion method with respect to atomic number (Z) by elucidating the role of partial photon interactions in the ΔHU-ρe conversion process. The authors performed numerical analyses of the ΔHU-ρe conversion for 105 human body tissues, as listed in ICRU Report 46, and elementary substances with Z = 1-40. Total and partial attenuation coefficients for these materials were calculated using the XCOM photon cross section database. The effective x-ray energies used to calculate the attenuation were chosen to imitate a dual-source CT scanner operated at 80-140 kV/Sn under well-calibrated and poorly calibrated conditions. The accuracy of the resultant calibrated electron density,[Formula: see text], for the ICRU-46 body tissues fully satisfied the IPEM-81 tolerance levels in radiotherapy treatment planning. If a criterion of [Formula: see text]ρe - 1 is assumed to be within ± 2%, the predicted upper limit of Z applicable for the ΔHU-ρe conversion under the well-calibrated condition is Z = 27. In the case of the poorly calibrated condition, the upper limit of Z is approximately 16. The deviation from the ΔHU-ρe linearity for higher Z substances is mainly caused by the anomalous variation in the photoelectric-absorption component. Compensation among the three partial components of the photon interactions provides for sufficient linearity of the ΔHU-ρe conversion to be applicable for most human tissues even for poorly conditioned scans in which there exists a large variation of effective x-ray energies owing to beam-hardening effects arising from the mismatch between the sizes of the object and the calibration phantom.

Cortical compression rapidly trimmed transcallosal projections and altered axonal anterograde transport machinery.

PubMed

Chen, Li-Jin; Wang, Yueh-Jan; Tseng, Guo-Fang

2017-10-24

Trauma and tumor compressing the brain distort underlying cortical neurons. Compressed cortical neurons remodel their dendrites instantly. The effects on axons however remain unclear. Using a rat epidural bead implantation model, we studied the effects of unilateral somatosensory cortical compression on its transcallosal projection and the reversibility of the changes following decompression. Compression reduced the density, branching profuseness and boutons of the projection axons in the contralateral homotopic cortex 1week and 1month post-compression. Projection fiber density was higher 1-month than 1-week post-compression, suggesting adaptive temporal changes. Compression reduced contralateral cortical synaptophysin, vesicular glutamate transporter 1 (VGLUT1) and postsynaptic density protein-95 (PSD95) expressions in a week and the first two marker proteins further by 1month. βIII-tubulin and kinesin light chain (KLC) expressions in the corpus callosum (CC) where transcallosal axons traveled were also decreased. Kinesin heavy chain (KHC) level in CC was temporarily increased 1week after compression. Decompression increased transcallosal axon density and branching profuseness to higher than sham while bouton density returned to sham levels. This was accompanied by restoration of synaptophysin, VGLUT1 and PSD95 expressions in the contralateral cortex of the 1-week, but not the 1-month, compression rats. Decompression restored βIII-tubulin, but not KLC and KHC expressions in CC. However, KLC and KHC expressions in the cell bodies of the layer II/III pyramidal neurons partially recovered. Our results show cerebral compression compromised cortical axonal outputs and reduced transcallosal projection. Some of these changes did not recover in long-term decompression. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Interface control document between the NASA Goddard Space Flight Center (GSFC) and Department of Interior EROS Data Center (EDC) for LANDSAT-D. Partially processed multispectral scanner High Density Tape (HDT-AM)

NASA Technical Reports Server (NTRS)

1982-01-01

The format of the HDT-AM product which contains partially processed LANDSAT D and D Prime multispectral scanner image data is defined. Recorded-data formats, tape format, and major frame types are described.

Light enpolarization by disordered media under partial polarized illumination: the role of cross-scattering coefficients.

PubMed

Zerrad, M; Soriano, G; Ghabbach, A; Amra, C

2013-02-11

We show how disordered media allow to increase the local degree of polarization (DOP) of an arbitrary (partial) polarized incident beam. The role of cross-scattering coefficients is emphasized, together with the probability density functions (PDF) of the scattering DOP. The average DOP of scattering is calculated versus the incident illumination DOP.

Vitamin D is associated with atheroprotective high-density lipoprotein profile in postmenopausal women

PubMed Central

Kazlauskaite, Rasa; Powell, Lynda H.; Mandapakala, Chaitanya; Cursio, John F.; Avery, Elizabeth F.; Calvin, James

2012-01-01

BACKGROUND Low vitamin D has been associated with low levels of high-density lipoprotein (HDL) cholesterol, a marker of coronary risk. Whether atheroprotective HDL particle composition accounts for this association and whether fat affects this association is not known. OBJECTIVE To explore the association between HDL particle composition and 25-hydroxy vitamin D (25[OH]D) in post-menopausal women. METHODS Vitamin D levels and lipoprotein composition were assessed in fasting blood samples of apparently healthy women from a diverse Chicago community. Visceral (VAT) and subcutaneous (SAT) abdominal fat area were assessed using computed tomography. Total body fat mass was measured by dual-energy X-ray absorptiometry. RESULTS We enrolled 78 women (50% black; 50% white), age 48 to 64 years, all of whom were participants in a longitudinal study of fat patterning. They had a mean 25[OH]D of 31 ± 15 µg/L, HDL cholesterol 57 ± 11 mg/dL, and large HDL particle subclass 8.6 ± 3.4 µmol/L. In a multivariable-adjusted regression model, each 5 µg/L higher 25[OH]D predicted 0.57 µmol/L (95%CI 0.20–0.95) higher large HDL particles, independent of race, season, and total HDL particle concentration. This association was only partially confounded by total body fat mass (0.49, 95%CI 0.10–0.89), SAT (0.50, 95%CI 0.11–0.90), or VAT (0.37, 95%CI 0.01–0.74). Age did not significantly influence the strength of associations. CONCLUSIONS Higher 25[OH]D levels are associated with large HDL particles. This association is stronger than that of HDL cholesterol and only partially confounded by body fat. Theoretically, vitamin D may protect against cardiovascular risk by promoting formation of large HDL particles, affecting reverse cholesterol transport. PMID:21122638

Effects of Different Saline-Alkaline Conditions on the Characteristics of Phytoplankton Communities in the Lakes of Songnen Plain, China

PubMed Central

Zang, Shuying; Fan, Yawen; Ye, Huaxiang

2016-01-01

Many lakes located in the Songnen Plain of China exhibit a high saline-alkaline level. 25 lakes in the Songnen Plain were selected as research objects in this study. Water samples in these lakes were collected from June to August in 2008. Total Dissolved Solids (TDS) and Total Alkalinity (TA) were measured to assess the saline-alkaline level, and partial canonical correspondence analysis (CCA) was conducted as well. The results show that the majority of these lakes in the study area could be categorized into HCO3−-Na+-I type. According to the TDS assessment, of the total 25 lakes, there are 14 for freshwater, 7 for brackish water and 4 for saltwater; and the respective range of TA was from 0.98 to 40.52. The relationship between TA and TDS indicated significant linear relationship (R2 = 0.9292) in the HCO3−-Na+-I type lakes in the Songnen Plain. There was a general trend that cell density, genera richness and taxonomic diversity decreased with the increase of saline-alkaline gradient, whereas a contrary trend was observed for the proportion of dominant species. When the TDS values were above 3×103mg/L and the TA values were above 15mg/L, there was a significant reduction in cell density, genera richness and biodiversity, and their corresponding values were respectively below 10×106 (ind/L), 15 and approximately 2.5. Through the partial canonical correspondence analysis (CCA), 10.7% of the genera variation was explained by pure saline-alkaline variables. Cyclotella meneghiniana, Melosira ambigua and Melosira granulate were found to become the dominant species in most of these lakes, which indicated that there may be rather wide saline-alkaline niches for common dominant species. About one-quarters of the genera which have certain tolerance to salinity and alkalinity preferred to live in the regions with relatively higher saline-alkaline levels in this study. PMID:27749936

The Relationship of Fat Distribution and Insulin Resistance with Lumbar Spine Bone Mass in Women

PubMed Central

de Paula, Francisco J. A.; de Araújo, Iana M.; Carvalho, Adriana L.; Elias, Jorge; Salmon, Carlos E. G.; Nogueira-Barbosa, Marcello H.

2015-01-01

Bone marrow harbors a significant amount of body adipose tissue (BMAT). While BMAT might be a source of energy for bone modeling and remodeling, its increment can also represent impairment of osteoblast differentiation. The relationship between BMAT, bone mass and insulin sensitivity is only partially understood and seems to depend on the circumstances. The present study was designed to assess the association of BMAT with bone mineral density in the lumbar spine as well as with visceral adipose tissue, intrahepatic lipids, HOMA-IR, and serum levels of insulin and glucose. This cross-sectional clinical investigation included 31 non-diabetic women, but 11 had a pre-diabetes status. Dual X-ray energy absorptiometry was used to measure bone mineral density and magnetic resonance imaging was used to assess fat deposition in BMAT, visceral adipose tissue and liver. Our results suggest that in non-diabetic, there is an inverse relationship between bone mineral density in lumbar spine and BMAT and a trend persists after adjustment for weight, age, BMI and height. While there is a positive association between visceral adipose tissue and intrahepatic lipids with serum insulin levels, there is no association between BMAT and serum levels of insulin. Conversely, a positive relationship was observed between BMAT and serum glucose levels, whereas this association was not observed with other fat deposits. These relationships did not apply after adjustment for body weight, BMI, height and age. The present study shows that in a group of predominantly non-obese women the association between insulin resistance and BMAT is not an early event, as occurs with visceral adipose tissue and intrahepatic lipids. On the other hand, BMAT has a negative relationship with bone mineral density. Taken together, the results support the view that bone has a complex and non-linear relationship with energy metabolism. PMID:26067489

The Relationship of Fat Distribution and Insulin Resistance with Lumbar Spine Bone Mass in Women.

PubMed

de Paula, Francisco J A; de Araújo, Iana M; Carvalho, Adriana L; Elias, Jorge; Salmon, Carlos E G; Nogueira-Barbosa, Marcello H

2015-01-01

Bone marrow harbors a significant amount of body adipose tissue (BMAT). While BMAT might be a source of energy for bone modeling and remodeling, its increment can also represent impairment of osteoblast differentiation. The relationship between BMAT, bone mass and insulin sensitivity is only partially understood and seems to depend on the circumstances. The present study was designed to assess the association of BMAT with bone mineral density in the lumbar spine as well as with visceral adipose tissue, intrahepatic lipids, HOMA-IR, and serum levels of insulin and glucose. This cross-sectional clinical investigation included 31 non-diabetic women, but 11 had a pre-diabetes status. Dual X-ray energy absorptiometry was used to measure bone mineral density and magnetic resonance imaging was used to assess fat deposition in BMAT, visceral adipose tissue and liver. Our results suggest that in non-diabetic, there is an inverse relationship between bone mineral density in lumbar spine and BMAT and a trend persists after adjustment for weight, age, BMI and height. While there is a positive association between visceral adipose tissue and intrahepatic lipids with serum insulin levels, there is no association between BMAT and serum levels of insulin. Conversely, a positive relationship was observed between BMAT and serum glucose levels, whereas this association was not observed with other fat deposits. These relationships did not apply after adjustment for body weight, BMI, height and age. The present study shows that in a group of predominantly non-obese women the association between insulin resistance and BMAT is not an early event, as occurs with visceral adipose tissue and intrahepatic lipids. On the other hand, BMAT has a negative relationship with bone mineral density. Taken together, the results support the view that bone has a complex and non-linear relationship with energy metabolism.

Optical conductivity of partially oxidized graphene from first principles

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

Nasehnia, F., E-mail: f.nasehnia@gmail.com; Seifi, M., E-mail: Seifi@guilan.ac.ir

2015-07-07

We investigate the geometry, electronic structure, and optical properties of partially oxidized graphene using density functional theory. Our calculations show that oxygen atoms are chemisorbed on graphene plane and distort carbon atoms vertically, with almost no change in the in-plane structure. The ground state configurations for different oxygen coverages ranging from 2% to 50% (O/C ratio) are calculated and show the strong tendency of oxygen adatoms to aggregate and form discrete islands on graphene plane. It is found that the opened band gap due to oxygen functionalization depends on the oxygen density and the adsorption configuration. The gap is notmore » significant for oxygen densities lower than 8%. The optical conductivities are calculated in the infrared, visible, and ultraviolet regions and show different characteristic features depending on the degree of oxidation. These results imply that optical measurement techniques can be employed to monitor oxidation (or reduction) process as contact-free methods.« less

Electronic structure of Ag7GeS5I superionic compound

NASA Astrophysics Data System (ADS)

Bletskan, Dmytro; Studenyak, Ihor; Bletskan, Mykhailo; Vakulchak, Vasyl

2018-05-01

This paper presents the originally results of ab initio calculations of electronic structure, total and partial densities of electronic states as well as electronic charge density distribution of Ag7GeS5I crystal performed within the density functional theory (DFT) in the local density approximation (LDA) for exchange-correlation potential. According to performed calculations, Ag7GeS5I is the direct-gap semiconductor with the valence band top and the conductivity band bottom in the Γ point of Brillouin zone. The band gap width calculated in the LDA-approximation is Egd = 0.73 eV. The analysis of total and partial densities of electronic states allow us to identify the atomic orbital contributions into the crystal orbitals as well as the formation data of chemical bond in the studied crystal. In the top part of Ag7GeS5I valence band it was revealed the considerable mixing (hybridization) of the occupied d-states of Ag noble metal and the delocalized p-states of sulfur and iodine, which is undoubtedly associated with the covalent character of chemical bond between S, I atoms and noble metal atom.

Partial Denervation of Subbasal Axons Persists Following Debridement Wounds to the Mouse Cornea

PubMed Central

Pajoohesh-Ganji, Ahdeah; Pal-Ghosh, Sonali; Tadvalkar, Gauri; Kyne, Briana M.; Saban, Daniel R.; Stepp, Mary Ann

2015-01-01

Although sensory reinnervation occurs after injury in the PNS, poor reinnervation in the elderly and those with diabetes often leads to pathology. Here we quantify subbasal axon density in the central and peripheral mouse cornea over time after three different types of injury. The mouse cornea is highly innervated with a dense array of subbasal nerves that form a spiral called the vortex at the corneal center or apex; these nerves are readily detected within flat mounted corneas. After anesthesia, corneal epithelial cells were removed using either a dulled blade or a rotating burr within an area demarcated centrally with a 1.5 mm trephine. A third wound type, superficial trephination, involved demarcating the area with the 1.5 mm trephine but not removing cells. By 7d after superficial trephination, subbasal axon density returns to control levels; by 28d the vortex reforms. Although axon density is similar to control 14d after dulled blade and rotating burr wounding, defects in axon morphology at the corneal apex remain. After 14d, axons retract from the center leaving the subbasal axon density reduced by 37.2% and 36.8% at 28d after dulled blade and rotating burr wounding, respectively, compared to control. Assessment of inflammation using flow cytometry shows that persistent inflammation is not a factor in the incomplete reinnervation. Expression of mRNAs encoding 22 regeneration associated genes (RAGs) involved in axon targeting assessed by QPCR reveals that netrin-1 and ephrin signaling are altered after wounding. Subpopulations of corneal epithelial basal cells at the corneal apex stop expressing ki67 as early as 7d after injury and by 14d and 28d after wounding, many of these basal cells undergo apoptosis and die. While subbasal axons are restored to their normal density and morphology after superficial trephination, subbasal axon recovery is partial after debridement wounds. The increase in corneal epithelial basal cell apoptosis at the apex observed at 14d after corneal debridement may destabilize newly reinnervated subbasal axons and lead to their retraction towards the periphery. PMID:26280222

Partial denervation of sub-basal axons persists following debridement wounds to the mouse cornea.

PubMed

Pajoohesh-Ganji, Ahdeah; Pal-Ghosh, Sonali; Tadvalkar, Gauri; Kyne, Briana M; Saban, Daniel R; Stepp, Mary Ann

2015-11-01

Although sensory reinnervation occurs after injury in the peripheral nervous system, poor reinnervation in the elderly and those with diabetes often leads to pathology. Here we quantify sub-basal axon density in the central and peripheral mouse cornea over time after three different types of injury. The mouse cornea is highly innervated with a dense array of sub-basal nerves that form a spiral called the vortex at the corneal center or apex; these nerves are readily detected within flat mounted corneas. After anesthesia, corneal epithelial cells were removed using either a dulled blade or a rotating burr within an area demarcated centrally with a 1.5 mm trephine. A third wound type, superficial trephination, involved demarcating the area with the 1.5 mm trephine but not removing cells. By 7 days after superficial trephination, sub-basal axon density returns to control levels; by 28 days the vortex reforms. Although axon density is similar to control 14 days after dulled blade and rotating burr wounding, defects in axon morphology at the corneal apex remain. After 14 days, axons retract from the center leaving the sub-basal axon density reduced by 37.2 and 36.8% at 28 days after dulled blade and rotating burr wounding, respectively, compared with control. Assessment of inflammation using flow cytometry shows that persistent inflammation is not a factor in the incomplete reinnervation. Expression of mRNAs encoding 22 regeneration-associated genes involved in axon targeting assessed by QPCR reveals that netrin-1 and ephrin signaling are altered after wounding. Subpopulations of corneal epithelial basal cells at the corneal apex stop expressing ki67 as early as 7 days after injury and by 14 and 28 days after wounding, many of these basal cells undergo apoptosis and die. Although sub-basal axons are restored to their normal density and morphology after superficial trephination, sub-basal axon recovery is partial after debridement wounds. The increase in corneal epithelial basal cell apoptosis at the apex observed at 14 days after corneal debridement may destabilize newly reinnervated sub-basal axons and lead to their retraction toward the periphery.

Effects of the impurity-host interactions on the nonradiative processes in ZnS:Cr

NASA Astrophysics Data System (ADS)

Tablero, C.

2010-11-01

There is a great deal of controversy about whether the behavior of an intermediate band in the gap of semiconductors is similar or not to the deep-gap levels. It can have significant consequences, for example, on the nonradiative recombination. In order to analyze the behavior of an intermediate band, we have considered the effect of the inward and outward displacements corresponding to breathing and longitudinal modes of Cr-doped ZnS and on the charge density for different processes involved in the nonradiative recombination using first-principles. This metal-doped zinc chalcogenide has a partially filled band within the host semiconductor gap. In contrast to the properties exhibited by deep-gap levels in other systems, we find small variations in the equilibrium configurations, forces, and electronic density around the Cr when the nonradiative recombination mechanisms modify the intermediate band charge. The charge density around the impurity is equilibrated in response to the perturbations in the equilibrium nuclear configuration and the charge of the intermediate band. The equilibration follows a Le Chatelier principle through the modification of the contribution from the impurity to the intermediate band and to the valence band. The intermediate band introduced by Cr in ZnS for the concentrations analyzed makes the electronic capture difficult and later multiphonon emission in the charge-transfer processes, in accordance with experimental results.

Avocado oil supplementation modifies cardiovascular risk profile markers in a rat model of sucrose-induced metabolic changes.

PubMed

Carvajal-Zarrabal, Octavio; Nolasco-Hipolito, Cirilo; Aguilar-Uscanga, M Guadalupe; Melo-Santiesteban, Guadalupe; Hayward-Jones, Patricia M; Barradas-Dermitz, Dulce M

2014-01-01

The purpose of this study was to evaluate the effects of avocado oil administration on biochemical markers of cardiovascular risk profile in rats with metabolic changes induced by sucrose ingestion. Twenty-five rats were divided into five groups: a control group (CG; basic diet), a sick group (MC; basic diet plus 30% sucrose solution), and three other groups (MCao, MCac, and MCas; basic diet plus 30% sucrose solution plus olive oil and avocado oil extracted by centrifugation or using solvent, resp.). Glucose, total cholesterol, triglycerides, phospholipids, low- and high-density lipoproteins (LDL, HDL), very low-density lipoprotein (VLDL), lactic dehydrogenase, creatine kinase, and high sensitivity C-reactive protein concentration were analyzed. Avocado oil reduces TG, VLDL, and LDL levels, in the LDL case significantly so, without affecting HDL levels. An effect was exhibited by avocado oil similar to olive oil, with no significant difference between avocado oil extracted either by centrifugation or solvent in myocardial injury biochemical indicators. Avocado oil decreased hs-CRP levels, indicating that inflammatory processes were partially reversed. These findings suggested that avocado oil supplementation has a positive health outcome because it reduces inflammatory events and produces positive changes in the biochemical indicators studied, related to the development of metabolic syndrome.

Study of the modes of adsorption and electronic structure of hydrogen peroxide and ethanol over TiO2 rutile (110) surface within the context of water splitting

NASA Astrophysics Data System (ADS)

Alghamdi, H.; Idriss, H.

2018-03-01

While photocatalytic water splitting over many materials is favourable thermodynamically the kinetic of the reaction is very slow. One of the proposed reasons linked to the slow oxidation reaction rate is H2O2 formation as a reaction intermediate. Using Density Functional Theory (DFT) H2O2 is investigated on TiO2 rutile (110) surface to determine its most stable adsorption modes: molecular, (H)O(H)O - (a), partially dissociated, (H)OO - (a), and fully dissociated (a) - OO - (a). We then compare H2O2 interaction to that of a fast hole scavenger molecule, ethanol. Geometry, electronic structure, charge density difference and work function determination of both adsorbates are presented and compared using DFT with different functionals (PBE, PBE-D, PBE-U, and HSE + D). H2O2 is found to be strongly adsorbed on TiO2 rutile (110) surface with adsorption energies reaching 0.95 eV, comparable to that of ethanol (0.89 eV); using GGA PBE. The negative changes in the work function upon adsorption were found to be highest for molecular adsorption ( - 1.23 eV) and lowest for the fully dissociated mode ( - 0.54 eV) of H2O2. This may indicate that electrons flow from the surface to the adsorbate in order to make O(s)-H partially offset the overall magnitude of the oxygen lone pair interaction (of H2O2) with Ti4+ cations. Examination of the electronic structure through density of states (DOS) at the PBE level of computation, indicates that the H2O2 highest occupied molecular orbital (HOMO) level is not overlapping with oxygen atoms of TiO2 surface at any of its adsorption modes and at any of the computation methods. Some overlap is seen using the HSE + D computational method. On the other hand the dissociated mode of ethanol (ethoxides) does overlap with all computational methods used. The high adsorption energy and the absence of overlapping of the HOMO level of H2O2 with TiO2 rutile (110) surface may explain why water splitting is slow.

Transport and NMR characteristics of the skutterudite-related compound Ca3Rh4Sn13

NASA Astrophysics Data System (ADS)

Tseng, C. W.; Kuo, C. N.; Li, B. S.; Wang, L. M.; Gippius, A. A.; Kuo, Y. K.; Lue, C. S.

2018-02-01

We report the electronic properties of the Yb3Rh4Sn13-type single crystalline Ca3Rh4Sn13 by means of the electrical resistivity, Hall coefficient, Seebeck coefficient, thermal conductivity, as well as 119Sn nuclear magnetic resonance (NMR) measurements. The negative sign of the Hall coefficient and Seebeck coefficient at low temperatures suggests that the n-type carriers dominate the electrical transport in Ca3Rh4Sn13, in contrast to the observations in Sr3Rh4Sn13 which has a p-type conduction. Such a finding indicates a significant difference in the electronic features between these two stannides. Furthermore, we analyzed the temperature-dependent 119Sn NMR spin-lattice relaxation rate for Ca3Rh4Sn13, (Sr0.7Ca0.3)3Rh4Sn13, and Sr3Rh4Sn13 to examine the change of the electronic Fermi-level density of states (DOS) in (Sr1-xCax)3Rh4Sn13. It indicates that the Sn 5s partial Fermi-level DOS enhances with increasing the Ca content, being consistent with the trend of the superconducting temperature. Since the total Fermi-level DOS usually obeys the same trend of the partial Fermi-level DOS, the NMR analysis provides microscopic evidence for the correlation between the electronic DOS and superconductivity of the (Sr1-xCax)3Rh4Sn13 system.

RIPL - Reference Input Parameter Library for Calculation of Nuclear Reactions and Nuclear Data Evaluations

NASA Astrophysics Data System (ADS)

Capote, R.; Herman, M.; Obložinský, P.; Young, P. G.; Goriely, S.; Belgya, T.; Ignatyuk, A. V.; Koning, A. J.; Hilaire, S.; Plujko, V. A.; Avrigeanu, M.; Bersillon, O.; Chadwick, M. B.; Fukahori, T.; Ge, Zhigang; Han, Yinlu; Kailas, S.; Kopecky, J.; Maslov, V. M.; Reffo, G.; Sin, M.; Soukhovitskii, E. Sh.; Talou, P.

2009-12-01

We describe the physics and data included in the Reference Input Parameter Library, which is devoted to input parameters needed in calculations of nuclear reactions and nuclear data evaluations. Advanced modelling codes require substantial numerical input, therefore the International Atomic Energy Agency (IAEA) has worked extensively since 1993 on a library of validated nuclear-model input parameters, referred to as the Reference Input Parameter Library (RIPL). A final RIPL coordinated research project (RIPL-3) was brought to a successful conclusion in December 2008, after 15 years of challenging work carried out through three consecutive IAEA projects. The RIPL-3 library was released in January 2009, and is available on the Web through http://www-nds.iaea.org/RIPL-3/. This work and the resulting database are extremely important to theoreticians involved in the development and use of nuclear reaction modelling (ALICE, EMPIRE, GNASH, UNF, TALYS) both for theoretical research and nuclear data evaluations. The numerical data and computer codes included in RIPL-3 are arranged in seven segments: MASSES contains ground-state properties of nuclei for about 9000 nuclei, including three theoretical predictions of masses and the evaluated experimental masses of Audi et al. (2003). DISCRETE LEVELS contains 117 datasets (one for each element) with all known level schemes, electromagnetic and γ-ray decay probabilities available from ENSDF in October 2007. NEUTRON RESONANCES contains average resonance parameters prepared on the basis of the evaluations performed by Ignatyuk and Mughabghab. OPTICAL MODEL contains 495 sets of phenomenological optical model parameters defined in a wide energy range. When there are insufficient experimental data, the evaluator has to resort to either global parameterizations or microscopic approaches. Radial density distributions to be used as input for microscopic calculations are stored in the MASSES segment. LEVEL DENSITIES contains phenomenological parameterizations based on the modified Fermi gas and superfluid models and microscopic calculations which are based on a realistic microscopic single-particle level scheme. Partial level densities formulae are also recommended. All tabulated total level densities are consistent with both the recommended average neutron resonance parameters and discrete levels. GAMMA contains parameters that quantify giant resonances, experimental gamma-ray strength functions and methods for calculating gamma emission in statistical model codes. The experimental GDR parameters are represented by Lorentzian fits to the photo-absorption cross sections for 102 nuclides ranging from 51V to 239Pu. FISSION includes global prescriptions for fission barriers and nuclear level densities at fission saddle points based on microscopic HFB calculations constrained by experimental fission cross sections.

RIPL - Reference Input Parameter Library for Calculation of Nuclear Reactions and Nuclear Data Evaluations

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

Capote, R.; Herman, M.; Oblozinsky, P.

We describe the physics and data included in the Reference Input Parameter Library, which is devoted to input parameters needed in calculations of nuclear reactions and nuclear data evaluations. Advanced modelling codes require substantial numerical input, therefore the International Atomic Energy Agency (IAEA) has worked extensively since 1993 on a library of validated nuclear-model input parameters, referred to as the Reference Input Parameter Library (RIPL). A final RIPL coordinated research project (RIPL-3) was brought to a successful conclusion in December 2008, after 15 years of challenging work carried out through three consecutive IAEA projects. The RIPL-3 library was released inmore » January 2009, and is available on the Web through (http://www-nds.iaea.org/RIPL-3/). This work and the resulting database are extremely important to theoreticians involved in the development and use of nuclear reaction modelling (ALICE, EMPIRE, GNASH, UNF, TALYS) both for theoretical research and nuclear data evaluations. The numerical data and computer codes included in RIPL-3 are arranged in seven segments: MASSES contains ground-state properties of nuclei for about 9000 nuclei, including three theoretical predictions of masses and the evaluated experimental masses of Audi et al. (2003). DISCRETE LEVELS contains 117 datasets (one for each element) with all known level schemes, electromagnetic and {gamma}-ray decay probabilities available from ENSDF in October 2007. NEUTRON RESONANCES contains average resonance parameters prepared on the basis of the evaluations performed by Ignatyuk and Mughabghab. OPTICAL MODEL contains 495 sets of phenomenological optical model parameters defined in a wide energy range. When there are insufficient experimental data, the evaluator has to resort to either global parameterizations or microscopic approaches. Radial density distributions to be used as input for microscopic calculations are stored in the MASSES segment. LEVEL DENSITIES contains phenomenological parameterizations based on the modified Fermi gas and superfluid models and microscopic calculations which are based on a realistic microscopic single-particle level scheme. Partial level densities formulae are also recommended. All tabulated total level densities are consistent with both the recommended average neutron resonance parameters and discrete levels. GAMMA contains parameters that quantify giant resonances, experimental gamma-ray strength functions and methods for calculating gamma emission in statistical model codes. The experimental GDR parameters are represented by Lorentzian fits to the photo-absorption cross sections for 102 nuclides ranging from {sup 51}V to {sup 239}Pu. FISSION includes global prescriptions for fission barriers and nuclear level densities at fission saddle points based on microscopic HFB calculations constrained by experimental fission cross sections.« less

RIPL-Reference Input Parameter Library for Calculation of Nuclear Reactions and Nuclear Data Evaluations

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

Capote, R.; Herman, M.; Capote,R.

We describe the physics and data included in the Reference Input Parameter Library, which is devoted to input parameters needed in calculations of nuclear reactions and nuclear data evaluations. Advanced modelling codes require substantial numerical input, therefore the International Atomic Energy Agency (IAEA) has worked extensively since 1993 on a library of validated nuclear-model input parameters, referred to as the Reference Input Parameter Library (RIPL). A final RIPL coordinated research project (RIPL-3) was brought to a successful conclusion in December 2008, after 15 years of challenging work carried out through three consecutive IAEA projects. The RIPL-3 library was released inmore » January 2009, and is available on the Web through http://www-nds.iaea.org/RIPL-3/. This work and the resulting database are extremely important to theoreticians involved in the development and use of nuclear reaction modelling (ALICE, EMPIRE, GNASH, UNF, TALYS) both for theoretical research and nuclear data evaluations. The numerical data and computer codes included in RIPL-3 are arranged in seven segments: MASSES contains ground-state properties of nuclei for about 9000 nuclei, including three theoretical predictions of masses and the evaluated experimental masses of Audi et al. (2003). DISCRETE LEVELS contains 117 datasets (one for each element) with all known level schemes, electromagnetic and {gamma}-ray decay probabilities available from ENSDF in October 2007. NEUTRON RESONANCES contains average resonance parameters prepared on the basis of the evaluations performed by Ignatyuk and Mughabghab. OPTICAL MODEL contains 495 sets of phenomenological optical model parameters defined in a wide energy range. When there are insufficient experimental data, the evaluator has to resort to either global parameterizations or microscopic approaches. Radial density distributions to be used as input for microscopic calculations are stored in the MASSES segment. LEVEL DENSITIES contains phenomenological parameterizations based on the modified Fermi gas and superfluid models and microscopic calculations which are based on a realistic microscopic single-particle level scheme. Partial level densities formulae are also recommended. All tabulated total level densities are consistent with both the recommended average neutron resonance parameters and discrete levels. GAMMA contains parameters that quantify giant resonances, experimental gamma-ray strength functions and methods for calculating gamma emission in statistical model codes. The experimental GDR parameters are represented by Lorentzian fits to the photo-absorption cross sections for 102 nuclides ranging from {sup 51}V to {sup 239}Pu. FISSION includes global prescriptions for fission barriers and nuclear level densities at fission saddle points based on microscopic HFB calculations constrained by experimental fission cross sections.« less

Hemispheric comparisons of neuron density in the planum temporale of schizophrenia and nonpsychiatric brains

PubMed Central

Smiley, John F.; Rosoklija, Gorazd; Mancevski, Branislav; Pergolizzi, Denise; Figarsky, Khadija; Bleiwas, Cynthia; Duma, Aleksej; Mann, J. John; Javitt, Daniel C.; Dwork, Andrew J.

2010-01-01

Postmortem and in vivo studies of schizophrenia frequently reveal reduced cortical volume, but the underlying cellular abnormalities are incompletely defined. One influential hypothesis, especially investigated in Brodmann’s area 9 of prefrontal cortex, is that the number of neurons is normal, and the volume change is caused by reduction of the surrounding neuropil. However, studies have differed on whether the cortex has the increased neuron density that is predicted by this hypothesis. In a recent study of bilateral planum temporale (PT), we reported smaller volume and width of the outer cortex (layers I-III), especially in the left hemisphere, among subjects with schizophrenia. In the present study, we measured neuron density and size in the same PT samples, and also in prefrontal area 9 of the same brains. In the PT, separate stereological measurements were made in layers II, IIIc, and VI, whereas area 9 was sampled in layer IIIb-c. In both cortical regions, there was no significant effect of schizophrenia on neuronal density or size. There was, nevertheless, a trend-level right>left hemispheric asymmetry of neuron density in the PT, which may partially explain the previously reported left>right asymmetry of cortical width. In schizophrenia, our findings suggest that closer packing of neurons may not always explain reduced cortical volume, and subtly decreased neuron number may be a contributing factor. PMID:21377842

Review of the hydrologic data-collection network in the St Joseph River basin, Indiana

USGS Publications Warehouse

Crompton, E.J.; Peters, J.G.; Miller, R.L.; Stewart, J.A.; Banaszak, K.J.; Shedlock, R.J.

1986-01-01

The St. Joseph River Basin data-collection network in the St. Joseph River for streamflow, lake, ground water, and climatic stations was reviewed. The network review included only the 1700 sq mi part of the basin in Indiana. The streamflow network includes 11 continuous-record gaging stations and one partial-record station. Based on areal distribution, lake effect , contributing drainage area, and flow-record ratio, six of these stations can be used to describe regional hydrology. Gaging stations on lakes are used to collect long-term lake-level data on which to base legal lake levels, and to monitor lake-level fluctuations after legal levels are established. More hydrogeologic data are needed for determining the degree to which grouhd water affects lake levels. The current groundwater network comprises 15 observation wells and has four purposes: (1) to determine the interaction between groundwater and lakes; (2) to measure changes in groundwater levels near irrigation wells; (3) to measure water levels in wells at special purpose sites; and (4) to measure long-term changes in water levels in areas not affected by pumping. Seven wells near three lakes have provided sufficient information for correlating water levels in wells and lakes but are not adequate to quantify the effect of groundwater on lake levels. Water levels in five observation wells located in the vicinity of intensive irrigation are not noticeably affected by seasonal withdrawals. The National Weather Sevice operates eight climatic stations in the basin primarily to characterize regional climatic conditions and to aid in flood forecasting. The network meets network-density guidelines established by the World Meterological Organization for collection of precipitation and evaporation data but not guidelines suggested by the National Weather Service for density of precipitation gages in areas of significant convective rainfalls. (Author 's abstract)

The determination of density and molecular weight distributions of lipoproteins by sedimentation equilibrium.

PubMed

Jeffrey, P D; Nichol, L W; Smith, G D

1975-01-25

A method is presented by which an experimental record of total concentration as a function of radial distance, obtained in a sedimentation equilibrium experiment conducted with a noninteracting mixture in the absence of a density gradient, may be analyzed to obtain the unimodal distributions of molecular weight and of partial molar volume when these vary concomitantly and continuously. Particular attention is given to the caracterization of classes of lipoproteins exhibiting Gaussian distributions of these quantities, although the analysis is applicable to other types of unimodal distribution. Equations are also formulated permitting the definition of the corresponding distributions of partial specific volume and of density. The analysis procedure is based on a method (employing Laplace transforms) developed previously, but differs from it in that it avoids the necessity of differentiating experimental results, which introduces error. The method offers certain advantages over other procedures used to characterize and compare lipoprotein samples (exhibiting unimodal distributions) with regard to the duration of the experiment, economy of the sample, and, particularly, the ability to define in principle all of the relevant distributions from one sedimentation equilibrium experiment and an external measurement of the weight average partial specific volume. These points and the steps in the analysis procedure are illustrated with experimental results obtained in the sedimentation equilibrium of a sample of human serum low density lipoprotein. The experimental parameters (such as solution density, column height, and angular velocity) used in the conduction of these experiments were selected on the basis of computer-simulated examples, which are also presented. These provide a guide for other workers interested in characterizing lipoproteins of this class.

Biomechanical effects of transverse partial sacrectomy on the sacroiliac joints: an in vitro human cadaveric investigation of the borderline of sacroiliac joint instability.

PubMed

Yu, Binsheng; Zheng, Zhaomin; Zhuang, Xinming; Chen, Hui; Xie, Denghui; Luk, K D K; Lu, W W

2009-06-01

In vitro laboratory study. To measure the effects of transverse partial sacrectomies on the compressive and torsional stiffness of the sacroiliac joints. Surgical treatment for sacral tumor of different location and nature includes partial or complete sacrectomy. Though the biomechanical investigations about the local destructive force of residual sacrum after partial sacrectomy have been reported, biomechanical properties of the residual sacroiliac joints after different transverse partial sacrectomies remain unknown. Seven fresh human cadaveric L5-pelves with normal bone mineral density were used in this study. Each specimen was tested in intact condition first, followed by a series of segmental transverse partial sacrectomies: under S2 partial sacrectomy (U-S2); U-(1/2)S2; U-S1; U-(1/2)S1; and right side sacroiliac joint resection (one-side). A material testing machine was used to apply 800 N compression and 7 Nm torsion loads through the L5/S1 joint. The resected dimensional area of sacroiliac joints and structural stiffness of the residual sacroiliac joints were analyzed. Average percentages of the resected area of sacroiliac joints were 8.4% in U-S2, 15.1% in U-(1/2)S2, 24.8% in U-S1, and 72.3% in U-(1/2)S1, respectively. In compression U-S2 approximately one-side preserved 98.7%, 97.1%, 94.4%, 82.9%, and 55.2% of the initial stiffness of the sacroiliac joint, respectively. No significant differences were detected among intact, U-S2, U-(1/2)S2, and U-S1 (P > 0.05). However, compressive stiffness of U-(1/2)S1 and one-side was markedly less than that of intact, U-S2, and U-(1/2)S2 (P < 0.05). In Torsion U-S2 approximately one-side preserved 90.7%, 88.5%, 81.9%, 71.9%, and 44.5% of the initial sacroiliac joint stiffness, respectively. No significant differences were demonstrated among intact, U-S2, and U-(1/2)S2 (P > 0.05); However, U-S1, U-(1/2)S1 and one-side exhibited significantly less torsional stiffness than intact and U-S2 (P < 0.05). In surgical treatment of distal sacral tumor, transverse partial sacrectomy involving S1 could result in rotational instability, and the resection level beyond (1/2)S1 further led to compressive instability. When the sacrectomy was at or above the S1/2 level, local reconstruction should be considered.

Wigner functions for nonparaxial, arbitrarily polarized electromagnetic wave fields in free space.

PubMed

Alonso, Miguel A

2004-11-01

New representations are defined for describing electromagnetic wave fields in free space exactly in terms of rays for any wavelength, level of coherence or polarization, and numerical aperture, as long as there are no evanescent components. These representations correspond to tensors assigned to each ray such that the electric and magnetic energy densities, the Poynting vector, and the polarization properties of the field correspond to simple integrals involving these tensors for the rays that go through the specified point. For partially coherent fields, the ray-based approach provided by the new representations can reduce dramatically the computation times for the physical properties mentioned earlier.

Effect of pressure on the Raman-active modes of zircon (ZrSiO4): a first-principles study

NASA Astrophysics Data System (ADS)

Sheremetyeva, Natalya; Cherniak, Daniele J.; Watson, E. Bruce; Meunier, Vincent

2018-02-01

Density-functional theory (DFT) was employed in a first-principles study of the effects of pressure on the Raman-active modes of zircon (ZrSiO4), using both the generalized gradient and local density approximations (GGA and LDA, respectively). Beginning with the equilibrium structure at zero pressure, we conducted a calibration of the effect of pressure in a manner procedurally similar to an experimental calibration. For pressures between 0 and 7 GPa, we find excellent qualitative agreement of frequency-pressure slopes partial ω /partial P calculated from GGA DFT with results of previous experimental studies. In addition, we were able to rationalize the ω vs. P behavior based on details of the vibrational modes and their atomic displacements. Most of the partial ω /partial P slopes are positive as expected, but the symmetry of the zircon lattice also results in two negative slopes for modes that involve slight shearing and rigid rotation of SiO4 tetrahedra. Overall, LDA yields absolute values of the frequencies of the Raman-active modes in good agreement with experimental values, while GGA reproduces the shift in frequency with pressure especially well.

Partial Agenesis and Hypoplasia of the Corpus Callosum in Idiopathic Autism

PubMed Central

Wegiel, Jarek; Flory, Michael; Kaczmarski, Wojciech; Brown, W. Ted; Chadman, Kathryn; Wisniewski, Thomas; Nowicki, Krzysztof; Kuchna, Izabela; Ma, Shuang Yong; Wegiel, Jerzy

2017-01-01

Abstract To test the hypothesis that developmental anomalies of the corpus callosum (CC), contribute to the pathogenesis of autism, we characterized the type, topography, and severity of CC pathology corresponding to reduced CC areas that are detected by magnetic resonance imaging in the brains of 11 individuals with autism and 11 controls. In the brains of 3 autistic subjects, partial CC agenesis resulted in complete or partial lack of interhemispheric axonal connections in CC segments III–V. In these cases, a combination of focal agenesis and uniform axonal deficit caused reduction of CC areas by 37%, of axon numbers by 62%, and of the numerical density of axons by 39%. In the CC of 8 autistic subjects without agenesis, there was an 18% deficit of the midsagittal CC area, 48.4% deficit of axon numbers, and 37% reduction of the numerical density of axons. The significantly thinner CC, reduced CC area, and uniform axonal deficit in all autistic subjects were classified as CC hypoplasia. Thus, the byproduct of partial CC agenesis and hypoplasia is reduction of axonal connections between cortical areas known to be involved in behavioral alterations observed in people with autism. PMID:28395085

Human respiration at rest in rapid compression and at high pressures and gas densities

NASA Technical Reports Server (NTRS)

Gelfand, R.; Lambertsen, C. J.; Strauss, R.; Clark, J. M.; Puglia, C. D.

1983-01-01

The ventilation (V), end-tidal PCO2 (PACO2), and CO2 elimination rate were determined in men at rest breathing CO2-free gas over the pressure range 1-50 ATA and the gas density range 0.4-25 g/l, during slow and rapid compressions, at stable elevated ambient pressures and during slow decompressions. Progressive increase in pulmonary gas flow resistance due to elevation of ambient pressure and inspired gas density to the He-O2 equivalent of 5000 feet of seawater was found to produce a complex pattern of change in PACO2. It was found that as both ambient pressure and pulmonary gas flow resistance were progressively raised, PACO2 at first increased, went through a maximum, and then declined towards values near the 1 ATA level. It is concluded that this pattern of PACO2 change results from the interaction on ventilation of the increase in pulmonary resistance due to the elevation of gas density with the increase in respiratory drive postulated as due to generalized central nervous system excitation associated with exposure to high hydrostatic pressure. It is suggested that a similar interaction exists between increased gas flow resistance and the increase in respiratory drive related to nitrogen partial pressure and the resulting narcosis.

Methionine deficiency in rats fed soy protein induces hypercholesterolemia and potentiates lipoprotein susceptibility to peroxidation.

PubMed

Moundras, C; Rémésy, C; Levrat, M A; Demigné, C

1995-09-01

A number of studies have provided evidence that plant proteins, especially soy protein, have a cholesterol-lowering effect as compared with casein. However, dietary supply of sulfur amino acids may be deficient when soy protein is present in the diet at a suboptimal level, which could affect lipid metabolism. Accordingly, in rats fed 13% protein diets, soy protein feeding resulted in a cholesterol-increasing effect (+18%), which could be counteracted by methionine supplementation (0.4%). In contrast, soy protein was effective in decreasing plasma triglyceride, as compared with levels in rats fed casein; this triglyceride-lowering effect was entirely abolished by methionine supplementation. The hypercholesterolemic effect of soy protein was characterized by a higher cholesterol content in low-density lipoprotein (LDL) and high-density lipoprotein 1 (HDL1) fractions, together with a marked induction of hepatic hydroxymethyl glutaryl coenzyme A (HMG CoA) reductase activity and to a lesser extent cholesterol 7 alpha-hydroxylase. There was practically no induction of these enzymes, as compared with levels in rats fed casein diets, when the soy protein diet was supplemented with methionine. Very-low-density lipoprotein (VLDL) plus LDL susceptibility to peroxidation was higher in rats fed soy protein than in casein-fed rats, which could reflect in part the lack of sulfur amino acid availability, since methionine supplementation led to a partial recovery of lipoprotein resistance to peroxidation. These findings suggest that amino acid imbalance could be atherogenic by increasing circulating cholesterol and leading to a higher lipoprotein susceptibility to peroxidation.

Behavioural flexibility in migratory behaviour in a long-lived large herbivore.

PubMed

Eggeman, Scott L; Hebblewhite, Mark; Bohm, Holger; Whittington, Jesse; Merrill, Evelyn H

2016-05-01

Migratory animals are predicted to enhance lifetime fitness by obtaining higher quality forage and/or reducing predation risk compared to non-migratory conspecifics. Despite evidence for behavioural flexibility in other taxa, previous research on large mammals has often assumed that migratory behaviour is a fixed behavioural trait. Migratory behaviour may be plastic for many species, although few studies have tested for individual-level flexibility using long-term monitoring of marked individuals, especially in large mammals such as ungulates. We tested variability in individual migratory behaviour using a 10-year telemetry data set of 223 adult female elk (Cervus elaphus) in the partially migratory Ya Ha Tinda population in Alberta, Canada. We used net squared displacement (NSD) to classify migratory strategy for each individual elk-year. Individuals switched between migrant and resident strategies at a mean rate of 15% per year, and migrants were more likely to switch than residents. We then tested how extrinsic (climate, elk/wolf abundance) and intrinsic (age) factors affected the probability of migrating, and, secondly, the decision to switch between migratory strategies. Over 630 individual elk-years, the probability of an individual elk migrating increased following a severe winter, in years of higher wolf abundance, and with increasing age. At an individual elk level, we observed 148 switching events of 430 possible transitions in elk monitored at least 2 years. We found switching was density-dependent, where migrants switched to a resident strategy at low elk abundance, but residents switched more to a migrant strategy at high elk abundance. Precipitation during the previous summer had a weak carryover effect, with migrants switching slightly more following wetter summers, whereas residents showed the opposite pattern. Older migrant elk rarely switched, whereas resident elk switched more frequently to migrate at older ages. Our results show migratory behaviour in ungulates is an individually variable trait that can respond to intrinsic, environmental and density-dependent forces. Different strategies had opposing responses to density-dependent and intrinsic drivers, providing a stabilizing mechanism for the maintenance of partial migration and demographic fitness in this population. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

Differential Acute and Chronic Effects of Leptin on Hypothalamic Astrocyte Morphology and Synaptic Protein Levels

PubMed Central

García-Cáceres, Cristina; Fuente-Martín, Esther; Burgos-Ramos, Emma; Granado, Miriam; Frago, Laura M.; Barrios, Vicente; Horvath, Tamas

2011-01-01

Astrocytes participate in neuroendocrine functions partially through modulation of synaptic input density in the hypothalamus. Indeed, glial ensheathing of neurons is modified by specific hormones, thus determining the availability of neuronal membrane space for synaptic inputs, with the loss of this plasticity possibly being involved in pathological processes. Leptin modulates synaptic inputs in the hypothalamus, but whether astrocytes participate in this action is unknown. Here we report that astrocyte structural proteins, such as glial fibrillary acidic protein (GFAP) and vimentin, are induced and astrocyte morphology modified by chronic leptin administration (intracerebroventricular, 2 wk), with these changes being inversely related to modifications in synaptic protein densities. Similar changes in glial structural proteins were observed in adult male rats that had increased body weight and circulating leptin levels due to neonatal overnutrition (overnutrition: four pups/litter vs. control: 12 pups/litter). However, acute leptin treatment reduced hypothalamic GFAP levels and induced synaptic protein levels 1 h after administration, with no effect on vimentin. In primary hypothalamic astrocyte cultures leptin also reduced GFAP levels at 1 h, with an induction at 24 h, indicating a possible direct effect of leptin. Hence, one mechanism by which leptin may affect metabolism is by modifying hypothalamic astrocyte morphology, which in turn could alter synaptic inputs to hypothalamic neurons. Furthermore, the responses to acute and chronic leptin exposure are inverse, raising the possibility that increased glial activation in response to chronic leptin exposure could be involved in central leptin resistance. PMID:21343257

Effects of partial sleep deprivation on slow waves during non-rapid eye movement sleep: A high density EEG investigation.

PubMed

Plante, David T; Goldstein, Michael R; Cook, Jesse D; Smith, Richard; Riedner, Brady A; Rumble, Meredith E; Jelenchick, Lauren; Roth, Andrea; Tononi, Giulio; Benca, Ruth M; Peterson, Michael J

2016-02-01

Changes in slow waves during non-rapid eye movement (NREM) sleep in response to acute total sleep deprivation are well-established measures of sleep homeostasis. This investigation utilized high-density electroencephalography (hdEEG) to examine topographic changes in slow waves during repeated partial sleep deprivation. Twenty-four participants underwent a 6-day sleep restriction protocol. Spectral and period-amplitude analyses of sleep hdEEG data were used to examine changes in slow wave energy, count, amplitude, and slope relative to baseline. Changes in slow wave energy were dependent on the quantity of NREM sleep utilized for analysis, with widespread increases during sleep restriction and recovery when comparing data from the first portion of the sleep period, but restricted to recovery sleep if the entire sleep episode was considered. Period-amplitude analysis was less dependent on the quantity of NREM sleep utilized, and demonstrated topographic changes in the count, amplitude, and distribution of slow waves, with frontal increases in slow wave amplitude, numbers of high-amplitude waves, and amplitude/slopes of low amplitude waves resulting from partial sleep deprivation. Topographic changes in slow waves occur across the course of partial sleep restriction and recovery. These results demonstrate a homeostatic response to partial sleep loss in humans. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Tape casting and partial melting of Bi-2212 thick films

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

Buhl, D.; Lang, T.; Heeb, B.

1994-12-31

To produce Bi-2212 thick films with high critical current densities tape casting and partial melting is a promising fabrication method. Bi-2212 powder and organic additives were mixed into a slurry and tape casted onto glass by the doctor blade tape casting process. The films were cut from the green tape and partially molten on Ag foils during heat treatment. We obtained almost single-phase and well-textured films over the whole thickness of 20 {mu}m. The orientation of the (a,b)-plane of the grains were parallel to the substrate with a misalignment of less than 6{degrees}. At 77K/OT a critical current density ofmore » 15`000 A/cm{sup 2} was reached in films of the dimension 1cm x 2cm x 20{mu}m (1{mu}V/cm criterion, resistively measured). At 4K/OT the highest value was 350`000 A/cm{sup 2} (1nV/cm criterion, magnetically measured).« less

Tape casting and partial melting of Bi-2212 thick films

NASA Technical Reports Server (NTRS)

Buhl, D.; Lang, TH.; Heeb, B.; Gauckler, L. J.

1995-01-01

To produce Bi-2212 thick films with high critical current densities tape casting and partial melting is a promising fabrication method. Bi-2212 powder and organic additives were mixed into a slurry and tape casted onto glass by the doctor blade tape casting process. The films were cut from the green tape and partially molten on Ag foils during heat treatment. We obtained almost single-phase and well-textured films over the whole thickness of 20 microns. The orientation of the (a,b)-plane of the grains was parallel to the substrate with a misalignment of less than 6 deg. At 77 K/0T a critical current density of 15, 000 A/sq cm was reached in films of the dimension 1 cm x 2 cm x 20 microns (1 micron V/cm criterion, resistively measured). At 4 K/0T the highest value was 350,000 A/sq cm (1 nV/cm criterion, magnetically measured).

Loss of migration and urbanization in birds: a case study of the blackbird (Turdus merula).

PubMed

Møller, Anders Pape; Jokimäki, Jukka; Skorka, Piotr; Tryjanowski, Piotr

2014-07-01

Many organisms have invaded urban habitats, although the underlying factors initially promoting urbanization remain poorly understood. Partial migration may facilitate urbanization because such populations benefit from surplus food in urban environments during winter, and hence enjoy reduced fitness costs of migratory deaths. We tested this hypothesis in the European blackbird Turdus merula, which has been urbanized since the 19th century, by compiling information on timing of urbanization, migratory status, and population density for 99 cities across the continent. Timing of urbanization was spatially auto-correlated at scales up to 600 km. Analyses of timing of urbanization revealed that urbanization occurred earlier in partially migratory and resident populations than in migratory populations of blackbirds. Independently, this effect was most pronounced in the range of the distribution that currently has the highest population density, suggesting that urbanization facilitated population growth. These findings are consistent with the hypothesis that timing of urbanization is facilitated by partial migration, resulting in subsequent residency and population growth.

Use of partial least squares regression to impute SNP genotypes in Italian cattle breeds.

PubMed

Dimauro, Corrado; Cellesi, Massimo; Gaspa, Giustino; Ajmone-Marsan, Paolo; Steri, Roberto; Marras, Gabriele; Macciotta, Nicolò P P

2013-06-05

The objective of the present study was to test the ability of the partial least squares regression technique to impute genotypes from low density single nucleotide polymorphisms (SNP) panels i.e. 3K or 7K to a high density panel with 50K SNP. No pedigree information was used. Data consisted of 2093 Holstein, 749 Brown Swiss and 479 Simmental bulls genotyped with the Illumina 50K Beadchip. First, a single-breed approach was applied by using only data from Holstein animals. Then, to enlarge the training population, data from the three breeds were combined and a multi-breed analysis was performed. Accuracies of genotypes imputed using the partial least squares regression method were compared with those obtained by using the Beagle software. The impact of genotype imputation on breeding value prediction was evaluated for milk yield, fat content and protein content. In the single-breed approach, the accuracy of imputation using partial least squares regression was around 90 and 94% for the 3K and 7K platforms, respectively; corresponding accuracies obtained with Beagle were around 85% and 90%. Moreover, computing time required by the partial least squares regression method was on average around 10 times lower than computing time required by Beagle. Using the partial least squares regression method in the multi-breed resulted in lower imputation accuracies than using single-breed data. The impact of the SNP-genotype imputation on the accuracy of direct genomic breeding values was small. The correlation between estimates of genetic merit obtained by using imputed versus actual genotypes was around 0.96 for the 7K chip. Results of the present work suggested that the partial least squares regression imputation method could be useful to impute SNP genotypes when pedigree information is not available.

Metabolic disregulation in obese adolescents with sleep-disordered breathing before and after weight loss.

PubMed

Van Hoorenbeeck, K; Franckx, H; Debode, P; Aerts, P; Ramet, J; Van Gaal, L F; Desager, K N; De Backer, W A; Verhulst, S L

2013-07-01

Sleep-disordered breathing (SDB) is prevalent in obesity. Weight loss is one of the most effective treatment options. The aim was to assess the association of SDB and metabolic disruption before and after weight loss. Obese adolescents were included when entering an in-patient weight loss program. Fasting blood analysis was performed at baseline and after 4-6 months. Sleep screening was done at baseline and at follow-up in case of baseline SDB. 224 obese adolescents were included. Median age was 15.5 years (10.1-18.0) and mean BMI z-score was 2.74 ± 0.42. About 30% had SDB at baseline (N = 68). High-density lipoprotein (HDL)-cholesterol was associated with mean nocturnal oxygen saturation () (partial r = 0.21; P = 0.002). Aspartate aminotransferase (ASAT) and alanine aminotransferase were related with oxygen desaturation index (partial r = -0.15; P = 0.03 and partial r = -0.15; P = 0.02), but this became insignificant after correction for sex. After weight loss, 24% had residual SDB. Linear regression showed an association between ASAT and (partial r = -0.34; P = 0.002). There were no significant correlations between improvements in laboratory measurements and sleep parameters. HDL-cholesterol improved in relation with the decrease in BMI z-score. SDB at baseline was associated with higher levels of liver enzymes and lower HDL-cholesterol concentration. Improvements in sleep parameters were not associated with improvements in laboratory measurements. Copyright © 2013 The Obesity Society.

Small dark energy and stable vacuum from Dilaton-Gauss-Bonnet coupling in TMT

NASA Astrophysics Data System (ADS)

Guendelman, Eduardo I.; Nishino, Hitoshi; Rajpoot, Subhash

2017-04-01

In two measures theories (TMT), in addition to the Riemannian measure of integration, being the square root of the determinant of the metric, we introduce a metric-independent density Φ in four dimensions defined in terms of scalars \\varphi _a by Φ =\\varepsilon ^{μ ν ρ σ } \\varepsilon _{abcd} (partial _{μ }\\varphi _a)(partial _{ν }\\varphi _b) (partial _{ρ }\\varphi _c) (partial _{σ }\\varphi _d). With the help of a dilaton field φ we construct theories that are globally scale invariant. In particular, by introducing couplings of the dilaton φ to the Gauss-Bonnet (GB) topological density {√{-g}} φ ( R_{μ ν ρ σ }^2 - 4 R_{μ ν }^2 + R^2 ) we obtain a theory that is scale invariant up to a total divergence. Integration of the \\varphi _a field equation leads to an integration constant that breaks the global scale symmetry. We discuss the stabilizing effects of the coupling of the dilaton to the GB-topological density on the vacua with a very small cosmological constant and the resolution of the `TMT Vacuum-Manifold Problem' which exists in the zero cosmological-constant vacuum limit. This problem generically arises from an effective potential that is a perfect square, and it gives rise to a vacuum manifold instead of a unique vacuum solution in the presence of many different scalars, like the dilaton, the Higgs, etc. In the non-zero cosmological-constant case this problem disappears. Furthermore, the GB coupling to the dilaton eliminates flat directions in the effective potential, and it totally lifts the vacuum-manifold degeneracy.

Effects of the bond polarity on the structural and dynamical properties of silica-like liquids

NASA Astrophysics Data System (ADS)

Pafong Sanjon, E.; Drossel, B.; Vogel, M.

2018-03-01

Silica is a network-forming liquid that shares many properties with water due to its tetrahedral structure. It undergoes a transition from a fragile to a strong liquid as the temperature is decreased, which is accompanied by a structural change to lower density and higher tetrahedral order. In order to disentangle the effects of Coulomb and van der Waals interactions on the structure and dynamics of liquid silica, we modify the bond polarity by changing the partial charges assigned to each atom. Using molecular dynamics simulations, we show that density, tetrahedral order, and structural relaxation times decrease when reducing bond polarity. Moreover, we find that the density maximum and the fragile-to-strong transition move to lower temperatures until they eventually vanish when the partial charges are decreased below approximately 75% of their regular value. Irrespective of whether strong or fragile behavior exists, structural relaxation is governed by hopping motion at sufficiently low temperatures. As long as there is a strong regime, the energy barrier associated with strong dynamics decreases with decreasing partial charges, but the dependence on the bond polarity differs from that of the activation energy in the Arrhenius regime at high temperatures. We show that the fragile-to-strong transition is associated with structural changes occurring between the first and second coordination shells that lead to a decrease in density and an increase in tetrahedral order. In particular, independent of the value of the partial charges, the distribution of the local structures is the same at this dynamic crossover, but we find no evidence that the effect occurs upon crossing the Widom line. In the fragile regime at intermediate temperatures, the relaxation times are well described by a previously proposed model which decomposes the apparent activation energy into a constant single-particle contribution and a temperature-dependent collective contribution. However, our results for silica-like melts do not obey several common relations of the model parameters reported for molecular glass formers.

Madelung and Hubbard interactions in polaron band model of doped organic semiconductors

PubMed Central

Png, Rui-Qi; Ang, Mervin C.Y.; Teo, Meng-How; Choo, Kim-Kian; Tang, Cindy Guanyu; Belaineh, Dagmawi; Chua, Lay-Lay; Ho, Peter K.H.

2016-01-01

The standard polaron band model of doped organic semiconductors predicts that density-of-states shift into the π–π* gap to give a partially filled polaron band that pins the Fermi level. This picture neglects both Madelung and Hubbard interactions. Here we show using ultrahigh workfunction hole-doped model triarylamine–fluorene copolymers that Hubbard interaction strongly splits the singly-occupied molecular orbital from its empty counterpart, while Madelung (Coulomb) interactions with counter-anions and other carriers markedly shift energies of the frontier orbitals. These interactions lower the singly-occupied molecular orbital band below the valence band edge and give rise to an empty low-lying counterpart band. The Fermi level, and hence workfunction, is determined by conjunction of the bottom edge of this empty band and the top edge of the valence band. Calculations are consistent with the observed Fermi-level downshift with counter-anion size and the observed dependence of workfunction on doping level in the strongly doped regime. PMID:27582355

Partial Genetic Deletion of Neuregulin 1 Modulates the Effects of Stress on Sensorimotor Gating, Dendritic Morphology, and HPA Axis Activity in Adolescent Mice

PubMed Central

Chohan, Tariq W.; Boucher, Aurelie A.; Spencer, Jarrah R.; Kassem, Mustafa S.; Hamdi, Areeg A.; Karl, Tim; Fok, Sandra Y.; Bennett, Maxwell R.; Arnold, Jonathon C.

2014-01-01

Stress has been linked to the pathogenesis of schizophrenia. Genetic variation in neuregulin 1 (NRG1) increases the risk of developing schizophrenia and may help predict which high-risk individuals will transition to psychosis. NRG1 also modulates sensorimotor gating, a schizophrenia endophenotype. We used an animal model to demonstrate that partial genetic deletion of Nrg1 interacts with stress to promote neurobehavioral deficits of relevance to schizophrenia. Nrg1 heterozygous (HET) mice displayed greater acute stress-induced anxiety-related behavior than wild-type (WT) mice. Repeated stress in adolescence disrupted the normal development of higher prepulse inhibition of startle selectively in Nrg1 HET mice but not in WT mice. Further, repeated stress increased dendritic spine density in pyramidal neurons of the medial prefrontal cortex (mPFC) selectively in Nrg1 HET mice. Partial genetic deletion of Nrg1 also modulated the adaptive response of the hypothalamic-pituitary-adrenal axis to repeated stress, with Nrg1 HET displaying a reduced repeated stress-induced level of plasma corticosterone than WT mice. Our results demonstrate that Nrg1 confers vulnerability to repeated stress-induced sensorimotor gating deficits, dendritic spine growth in the mPFC, and an abberant endocrine response in adolescence. PMID:24442851

Optimization of magnetic flux density for fast MREIT conductivity imaging using multi-echo interleaved partial fourier acquisitions.

PubMed

Chauhan, Munish; Jeong, Woo Chul; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

2013-08-27

Magnetic resonance electrical impedance tomography (MREIT) has been introduced as a non-invasive method for visualizing the internal conductivity and/or current density of an electrically conductive object by externally injected currents. The injected current through a pair of surface electrodes induces a magnetic flux density distribution inside the imaging object, which results in additional magnetic flux density. To measure the magnetic flux density signal in MREIT, the phase difference approach in an interleaved encoding scheme cancels out the systematic artifacts accumulated in phase signals and also reduces the random noise effect by doubling the measured magnetic flux density signal. For practical applications of in vivo MREIT, it is essential to reduce the scan duration maintaining spatial-resolution and sufficient contrast. In this paper, we optimize the magnetic flux density by using a fast gradient multi-echo MR pulse sequence. To recover the one component of magnetic flux density Bz, we use a coupled partial Fourier acquisitions in the interleaved sense. To prove the proposed algorithm, we performed numerical simulations using a two-dimensional finite-element model. For a real experiment, we designed a phantom filled with a calibrated saline solution and located a rubber balloon inside the phantom. The rubber balloon was inflated by injecting the same saline solution during the MREIT imaging. We used the multi-echo fast low angle shot (FLASH) MR pulse sequence for MRI scan, which allows the reduction of measuring time without a substantial loss in image quality. Under the assumption of a priori phase artifact map from a reference scan, we rigorously investigated the convergence ratio of the proposed method, which was closely related with the number of measured phase encode set and the frequency range of the background field inhomogeneity. In the phantom experiment with a partial Fourier acquisition, the total scan time was less than 6 seconds to measure the magnetic flux density Bz data with 128×128 spacial matrix size, where it required 10.24 seconds to fill the complete k-space region. Numerical simulation and experimental results demonstrated that the proposed method reduces the scanning time and provides the recovered Bz data comparable to what we obtained by measuring complete k-space data.

Some New Sets of Sequences of Fuzzy Numbers with Respect to the Partial Metric

PubMed Central

Ozluk, Muharrem

2015-01-01

In this paper, we essentially deal with Köthe-Toeplitz duals of fuzzy level sets defined using a partial metric. Since the utilization of Zadeh's extension principle is quite difficult in practice, we prefer the idea of level sets in order to construct some classical notions. In this paper, we present the sets of bounded, convergent, and null series and the set of sequences of bounded variation of fuzzy level sets, based on the partial metric. We examine the relationships between these sets and their classical forms and give some properties including definitions, propositions, and various kinds of partial metric spaces of fuzzy level sets. Furthermore, we study some of their properties like completeness and duality. Finally, we obtain the Köthe-Toeplitz duals of fuzzy level sets with respect to the partial metric based on a partial ordering. PMID:25695102

The Partial Molar Volume and Compressibility of the FeO Component in Model Basalts (Mixed CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6 Liquids) at 0 GPa: evidence of Fe2+ in 6-fold coordination

NASA Astrophysics Data System (ADS)

Guo, X.; Lange, R. A.; Ai, Y.

2010-12-01

FeO is an important component in magmatic liquids and yet its partial molar volume at one bar is not as well known as that for Fe2O3 because of the difficulty of performing double-bob density measurements under reducing conditions. Moreover, there is growing evidence from spectroscopic studies that Fe2+ occurs in 4, 5, and 6-fold coordination in silicate melts, and it is expected that the partial molar volume and compressibility of the FeO component will vary accordingly. We have conducted both density and relaxed sound speed measurements on four liquids in the An-Di-Hd (CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6) system: (1) Di-Hd (50:50), (2) An-Hd (50:50), (3) An-Di-Hd (33:33:33) and (4) Hd (100). Densities were measured between 1573 and 1838 K at one bar with the double-bob Archimedean method using molybdenum bobs and crucibles in a reducing gas (1%CO-99%Ar) environment. The sound speeds were measured under similar conditions with a frequency-sweep acoustic interferometer, and used to calculate isothermal compressibility. All the density data for the three multi-component (model basalt) liquids were combined with density data on SiO2-Al2O3-CaO-MgO-K2O-Na2O liquids (Lange, 1997) in a fit to a linear volume equation; the results lead to a partial molar volume (±1σ) for FeO =11.7 ± 0.3(±1σ) cm3/mol at 1723 K. This value is similar to that for crystalline FeO at 298 K (halite structure; 12.06 cm3/mol), which suggests an average Fe2+ coordination of ~6 in these model basalt compositions. In contrast, the fitted partial molar volume of FeO in pure hedenbergite liquid is 14.6 ± 0.3 at 1723 K, which is consistent with an average Fe2+ coordination of 4.3 derived from EXAFS spectroscopy (Rossano, 2000). Similarly, all the compressibility data for the three multi-component liquids were combined with compressibility data on SiO2-Al2O3-CaO-MgO liquids (Ai and Lange, 2008) in a fit to an ideal mixing model for melt compressibility; the results lead to a partial molar compressibility (±1σ) for FeO = 2.4 (± 0.3) 10-2 GPa-1 at 1723 K. In contrast, the compressibility of FeO in pure hedenbergite liquid is more than twice as large: 6.3 (± 0.2) 10-2 GPa-1. When these results are combined with density and sound speed data on CaO-FeO-SiO2 liquids at one bar (Guo et al., 2009), a systematic and linear variation between the partial molar volume and compressibility of the FeO component is obtained, which appears to track changes in the average Fe2+ coordination in these liquids. Therefore, the three most important conclusions of this study are: (1) ideal mixing of volume and compressibility does not occur for all FeO-bearing magmatic liquids, owing to changes in Fe2+ coordination, (2) the partial molar volume and compressibility of FeO varies linearly and systematically with Fe2+ coordination, and (3) ideal mixing of volume and compressibility does occur among the three mixed An-Di-Hd liquids, presumably because of a common, average Fe2+ coordination of ~6.

Experimental investigation of thermodynamic properties of binary mixture of acetic acid + n-butanol and acetic acid + water at temperature from 293.15 K to 343.15 K

NASA Astrophysics Data System (ADS)

Paul, M. Danish John; Shruthi, N.; Anantharaj, R.

2018-04-01

The derived thermodynamic properties like excess molar volume, partial molar volume, excess partial molar volume and apparent volume of binary mixture of acetic acid + n-butanolandacetic acid + water has been investigated using measured density of mixtures at temperatures from 293.15 K to 343.15.

46 CFR 171.052 - Passenger heel requirements for pontoon vessels.

Code of Federal Regulations, 2014 CFR

2014-10-01

... on exposed or partially protected waters— (i) 10 foot-degrees with a crowding density of 5 square feet per person (2.15 persons per square meter); and (ii) 7 foot-degrees with a crowding density of 2 square feet per person (5.38 persons per square meter); and (2) For operation on protected waters— (i) 5...

46 CFR 171.052 - Passenger heel requirements for pontoon vessels.

Code of Federal Regulations, 2012 CFR

2012-10-01

... on exposed or partially protected waters— (i) 10 foot-degrees with a crowding density of 5 square feet per person (2.15 persons per square meter); and (ii) 7 foot-degrees with a crowding density of 2 square feet per person (5.38 persons per square meter); and (2) For operation on protected waters— (i) 5...

46 CFR 171.052 - Passenger heel requirements for pontoon vessels.

Code of Federal Regulations, 2011 CFR

2011-10-01

... on exposed or partially protected waters— (i) 10 foot-degrees with a crowding density of 5 square feet per person (2.15 persons per square meter); and (ii) 7 foot-degrees with a crowding density of 2 square feet per person (5.38 persons per square meter); and (2) For operation on protected waters— (i) 5...

46 CFR 171.052 - Passenger heel requirements for pontoon vessels.

Code of Federal Regulations, 2013 CFR

2013-10-01

... on exposed or partially protected waters— (i) 10 foot-degrees with a crowding density of 5 square feet per person (2.15 persons per square meter); and (ii) 7 foot-degrees with a crowding density of 2 square feet per person (5.38 persons per square meter); and (2) For operation on protected waters— (i) 5...

Ultralow-power local laser control of the dimer density in alkali-metal vapors through photodesorption

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

Jha, Pankaj K.; Scully, Marlan O.; Princeton University, Princeton, New Jersey 08544

2012-08-27

Ultralow-power diode-laser radiation is employed to induce photodesorption of cesium from a partially transparent thin-film cesium adsorbate on a solid surface. Using resonant Raman spectroscopy, we demonstrate that this photodesorption process enables an accurate local optical control of the density of dimer molecules in alkali-metal vapors.

Dry chips versus green chips as furnish for medium-density fiberboard

Treesearch

Paul H. Short; George E. Woodson; Duane E. Lyon

1978-01-01

The fiber characteristics and the physical and mechanical properties of medium-density fiberboard (MDF), manufactured with pressure-refined fiber from green and partially dried raw material, were analyzed to determine if dry wood chips made a better furnish than green wood chips. Pressure-refining dry material produced coarser fiber than those obtained from green...

Dry chips versus green chips as furnish for medium-density fiberboard

Treesearch

P.H. Short; G.E. Woodson; D.E. Lyon

1978-01-01

The fiber characteristics and the physical and mechanical properties of medium-density fiberboard (MDF), manufactured with pressure-refined fiber from green and partially dried raw material, were analyzed to determine if dry wood chips made a better furnish than green wood chips. Pressure-refined dry material produced coarser fiber than those obtained from green...

Stimulation of acid secretion and phosphoinositol production by rat parietal cell muscarinic M sub 2 receptors

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

Pfeiffer, A.; Rochlitz, H.; Herz, A.

The muscarinic receptor system involved in hydrogen production by enriched rat gastric parietal cells was investigated. Muscarinic receptor density determined by (N-methyl-{sup 3}H)scopolamine binding was 8,100/cell. The receptor appeared to be of the M{sub 2} muscarinic receptor subtype, since it had a low affinity (K{sub d} 189 nM) for the M{sub 1} receptor antagonist pirenzepine compared with atropine. Receptor activation by carbachol rapidly augmented levels of polyphosphoinositides, indicating an activation of phospholipase C. The dose-response relations for the increase in inositol phosphates closely paralleled the binding of carbachol to muscarinic receptors. The inositol phosphate response was antagonized by pirenzepine withmore » a K{sub i} of 177 nM. the stimulation of inositol phosphate levels by carbachol correlated well with the stimulation of ({sup 14}C)aminopyrine uptake, determine as an index of acid secretion. The muscarinic agonists oxotremorine, pilocarpine, and bethanechol elicited partial increases in inositol phosphates at maximal drug concentrations, and these partial increases correlated with their ability to stimulate ({sup 14}C)aminopyrine uptake. These data indicate that inositolpolyphosphates may be a second messenger of M{sub 2} receptors stimulating acid secretion.« less

A cross-diffusion system derived from a Fokker-Planck equation with partial averaging

NASA Astrophysics Data System (ADS)

Jüngel, Ansgar; Zamponi, Nicola

2017-02-01

A cross-diffusion system for two components with a Laplacian structure is analyzed on the multi-dimensional torus. This system, which was recently suggested by P.-L. Lions, is formally derived from a Fokker-Planck equation for the probability density associated with a multi-dimensional Itō process, assuming that the diffusion coefficients depend on partial averages of the probability density with exponential weights. A main feature is that the diffusion matrix of the limiting cross-diffusion system is generally neither symmetric nor positive definite, but its structure allows for the use of entropy methods. The global-in-time existence of positive weak solutions is proved and, under a simplifying assumption, the large-time asymptotics is investigated.

Carbon Dioxide Electroreduction into Syngas Boosted by a Partially Delocalized Charge in Molybdenum Sulfide Selenide Alloy Monolayers.

PubMed

Xu, Jiaqi; Li, Xiaodong; Liu, Wei; Sun, Yongfu; Ju, Zhengyu; Yao, Tao; Wang, Chengming; Ju, Huanxin; Zhu, Junfa; Wei, Shiqiang; Xie, Yi

2017-07-24

Structural parameters of ternary transition-metal dichalcogenide (TMD) alloy usually obey Vegard law well, while interestingly it often exhibits boosted electrocatalytic performances relative to its two pristine binary TMDs. To unveil the underlying reasons, we propose an ideal model of ternary TMDs alloy monolayer. As a prototype, MoSeS alloy monolayers are successfully synthesized, in which X-ray absorption fine structure spectroscopy manifests their shortened Mo-S and lengthened Mo-Se bonds, helping to tailor the d-band electronic structure of Mo atoms. Density functional theory calculations illustrate an increased density of states near their conduction band edge, which ensures faster electron transfer confirmed by their lower work function and smaller charge-transfer resistance. Energy calculations show the off-center charge around Mo atoms not only benefits for stabilizing COOH* intermediate confirmed by its most negative formation energy, but also facilitates the rate-limiting CO desorption step verified by CO temperature programmed desorption and electro-stripping tests. As a result, MoSeS alloy monolayers attain the highest 45.2 % Faradaic efficiency for CO production, much larger than that of MoS 2 monolayers (16.6 %) and MoSe 2 monolayers (30.5 %) at -1.15 V vs. RHE. This work discloses how the partially delocalized charge in ternary TMDs alloys accelerates electrocatalytic performances at atomic level, opening new horizons for manipulating CO 2 electroreduction properties. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Nitrogen-Doped Carbon Catalyst for Electrochemical CO2 Conversion to CO with High Selectivity and Current Density.

PubMed

Jhong, Huei-Ru Molly; Tornow, Claire E; Smid, Bretislav; Gewirth, Andrew A; Lyth, Stephen M; Kenis, Paul J A

2017-03-22

We report characterization of a non-precious metal-free catalyst for the electrochemical reduction of CO 2 to CO; namely, a pyrolyzed carbon nitride and multiwall carbon nanotube composite. This catalyst exhibits a high selectivity for production of CO over H 2 (approximately 98 % CO and 2 % H 2 ), as well as high activity in an electrochemical flow cell. The CO partial current density at intermediate cathode potentials (V=-1.46 V vs. Ag/AgCl) is up to 3.5× higher than state-of-the-art Ag nanoparticle-based catalysts, and the maximum current density is 90 mA cm -2 . The mass activity and energy efficiency (up to 48 %) were also higher than the Ag nanoparticle reference. Moving away from precious metal catalysts without sacrificing activity or selectivity may significantly enhance the prospects of electrochemical CO 2 reduction as an approach to reduce atmospheric CO 2 emissions or as a method for load-leveling in relation to the use of intermittent renewable energy sources. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microscopic origin of the charge transfer in single crystals based on thiophene derivatives: A combined NEXAFS and density functional theory approach

NASA Astrophysics Data System (ADS)

Chernenkaya, A.; Morherr, A.; Backes, S.; Popp, W.; Witt, S.; Kozina, X.; Nepijko, S. A.; Bolte, M.; Medjanik, K.; Öhrwall, G.; Krellner, C.; Baumgarten, M.; Elmers, H. J.; Schönhense, G.; Jeschke, H. O.; Valentí, R.

2016-07-01

We have investigated the charge transfer mechanism in single crystals of DTBDT-TCNQ and DTBDT-F4TCNQ (where DTBDT is dithieno[2,3-d;2',3'-d'] benzo[1,2-b;4,5-b']dithiophene) using a combination of near-edge X-ray absorption spectroscopy (NEXAFS) and density functional theory calculations (DFT) including final state effects beyond the sudden state approximation. In particular, we find that a description that considers the partial screening of the electron-hole Coulomb correlation on a static level as well as the rearrangement of electronic density shows excellent agreement with experiment and allows to uncover the details of the charge transfer mechanism in DTBDT-TCNQ and DTBDT-F4 TCNQ, as well as a reinterpretation of previous NEXAFS data on pure TCNQ. Finally, we further show that almost the same quality of agreement between theoretical results and experiment is obtained by the much faster Z+1/2 approximation, where the core hole effects are simulated by replacing N or F with atomic number Z with the neighboring atom with atomic number Z+1/2.

Does cochlear implantation and electrical stimulation affect residual hair cells and spiral ganglion neurons?

PubMed Central

Coco, Anne; Epp, Stephanie B.; Fallon, James B.; Xu, Jin; Millard, Rodney E.; Shepherd, Robert K.

2007-01-01

Increasing numbers of cochlear implant subjects have some level of residual hearing at the time of implantation. The present study examined whether (i) hair cells that have survived one pathological insult (aminoglycoside deafening), can survive and function following long-term cochlear implantation and electrical stimulation (ES); and (ii) chronic ES in these cochleae results in greater trophic support of spiral ganglion neurons (SGNs) compared with cochleae devoid of hair cells. Eight cats, with either partial (n=4) or severe (n=4) sensorineural hearing loss, were bilaterally implanted with scala tympani electrode arrays 2 months after deafening, and received unilateral ES using charge balanced biphasic current pulses for periods of up to 235 days. Frequency-specific compound action potentials and click-evoked auditory brainstem responses (ABRs) were recorded periodically to monitor the residual acoustic hearing. Electrically-evoked ABRs (EABRs) were recorded to confirm the stimulus levels were 3-6 dB above the EABR threshold. On completion of the ES program the cochleae were examined histologically. Partially deafened animals showed no significant increase in acoustic thresholds over the implantation period. Moreover, chronic ES of an electrode array located in the base of the cochlea did not adversely affect hair cells in the middle or apical turns. There was evidence of a small but statistically significant rescue of SGNs in the middle and apical turns of stimulated cochleae in animals with partial hearing. Chronic ES did not, however, prevent a reduction in SGN density for the severely deaf cohort, although SGNs adjacent to the stimulating electrodes did exhibit a significant increase in soma area (p<0.01). In sum, chronic ES in partial hearing animals does not adversely affect functioning residual hair cells apical to the electrode array. Moreover, while there is an increase in the soma area of SGNs close to the stimulating electrodes in severely deaf cochleae, this trophic effect does not result in increased SGN survival. PMID:17258411

Computing partial traces and reduced density matrices

NASA Astrophysics Data System (ADS)

Maziero, Jonas

Taking partial traces (PTrs) for computing reduced density matrices, or related functions, is a ubiquitous procedure in the quantum mechanics of composite systems. In this paper, we present a thorough description of this function and analyze the number of elementary operations (ops) needed, under some possible alternative implementations, to compute it on a classical computer. As we note, it is worthwhile doing some analytical developments in order to avoid making null multiplications and sums, what can considerably reduce the ops. For instance, for a bipartite system ℋa⊗ℋb with dimensions da=dimℋa and db=dimℋb and for da,db≫1, while a direct use of PTr definition applied to ℋb requires 𝒪(da6db6) ops, its optimized implementation entails 𝒪(da2db) ops. In the sequence, we regard the computation of PTrs for general multipartite systems and describe Fortran code provided to implement it numerically. We also consider the calculation of reduced density matrices via Bloch’s parametrization with generalized Gell Mann’s matrices.

Understanding the effects of packing and chemical terminations on the optical excitations of azobenzene-functionalized self-assembled monolayers

NASA Astrophysics Data System (ADS)

Cocchi, Caterina; Draxl, Claudia

2017-10-01

In a first-principles study based on many-body perturbation theory, we analyze the optical excitations of azobenzene-functionalized self-assembled monolayers (SAMs) with increasing packing density and different terminations, considering for comparison the corresponding gas-phase molecules and dimers. Intermolecular coupling increases with the density of the chromophores independently of the functional groups. The intense π → π* resonance that triggers photo-isomerization is present in the spectra of isolated dimers and diluted SAMs, but it is almost completely washed out in tightly packed architectures. Intermolecular coupling is partially inhibited by mixing differently functionalized azobenzene derivatives, in particular when large groups are involved. In this way, the excitation band inducing the photo-isomerization process is partially preserved and the effects of dense packing partly counterbalanced. Our results suggest that a tailored design of azobenzene-functionalized SAMs which optimizes the interplay between the packing density of the chromophores and their termination can lead to significant improvements in the photo-switching efficiency of these systems.

Structural and mechanical features of the order-disorder transition in experimental hard-sphere packings

NASA Astrophysics Data System (ADS)

Hanifpour, M.; Francois, N.; Robins, V.; Kingston, A.; Vaez Allaei, S. M.; Saadatfar, M.

2015-06-01

Here we present an experimental and numerical investigation on the grain-scale geometrical and mechanical properties of partially crystallized structures made of macroscopic frictional grains. Crystallization is inevitable in arrangements of monosized hard spheres with packing densities exceeding Bernal's limiting density ϕBernal≈0.64 . We study packings of monosized hard spheres whose density spans over a wide range (0.59 <ϕ <0.72 ) . These experiments harness x-ray computed tomography, three-dimensional image analysis, and numerical simulations to access precisely the geometry and the 3D structure of internal forces within the sphere packings. We show that clear geometrical transitions coincide with modifications of the mechanical backbone of the packing both at the grain and global scale. Notably, two transitions are identified at ϕBernal≈0.64 and ϕc≈0.68 . These results provide insights on how geometrical and mechanical features at the grain scale conspire to yield partially crystallized structures that are mechanically stable.

A comparison of soil climate and biological activity along an elevation gradient in the eastern Mojave Desert

USGS Publications Warehouse

Amundson, R.G.; Chadwick, O.A.; Sowers, J.M.

1989-01-01

Soil temperature, moisture, and CO2 were monitored at four sites along an elevation transect in the eastern Mojave Desert from January to October, 1987. Climate appeared to be the major factor controlling CO2 partial pressures, primarily through its influence of rates of biological reactions, vegetation densities, and organic matter production. With increasing elevation, and increasing actual evapotranspiration, the organic C, plant density, and the CO2 content of the soils increased. Between January and May, soil CO2 concentrations at a given site were closely related to variations in soil temperature. In July and October, temperatures had little effect on CO2, presumably due to low soil moisture levels. Up to 75% of litter placed in the field in March was lost by October whereas, for the 3 lower elevations, less than 10% of the litter placed in the field in April was lost through decomposition processes. ?? 1989 Springer-Verlag.

Convolutionless Nakajima-Zwanzig equations for stochastic analysis in nonlinear dynamical systems.

PubMed

Venturi, D; Karniadakis, G E

2014-06-08

Determining the statistical properties of stochastic nonlinear systems is of major interest across many disciplines. Currently, there are no general efficient methods to deal with this challenging problem that involves high dimensionality, low regularity and random frequencies. We propose a framework for stochastic analysis in nonlinear dynamical systems based on goal-oriented probability density function (PDF) methods. The key idea stems from techniques of irreversible statistical mechanics, and it relies on deriving evolution equations for the PDF of quantities of interest, e.g. functionals of the solution to systems of stochastic ordinary and partial differential equations. Such quantities could be low-dimensional objects in infinite dimensional phase spaces. We develop the goal-oriented PDF method in the context of the time-convolutionless Nakajima-Zwanzig-Mori formalism. We address the question of approximation of reduced-order density equations by multi-level coarse graining, perturbation series and operator cumulant resummation. Numerical examples are presented for stochastic resonance and stochastic advection-reaction problems.

Enhancement of in vitro high-density polyethylene (HDPE) degradation by physical, chemical, and biological treatments.

PubMed

Balasubramanian, V; Natarajan, K; Rajeshkannan, V; Perumal, P

2014-11-01

Partially degraded high-density polyethylene (HDPE) was collected from plastic waste dump yard for biodegradation using fungi. Of various fungi screened, strain MF12 was found efficient in degrading HDPE by weight loss and Fourier transform infrared (FT-IR) spectrophotometric analysis. Strain MF12 was selected as efficient HDPE degraders for further studies, and their growth medium composition was optimized. Among those different media used, basal minimal medium (BMM) was suitable for the HDPE degradation by strain MF12. Strain MF12 was subjected to 28S rRNA sequence analysis and identified as Aspergillus terreus MF12. HDPE degradation was carried out using combinatorial physical and chemical treatments in conjunction to biological treatment. The high level of HDPE degradation was observed in ultraviolet (UV) and KMnO4/HCl with A. terreus MF12 treatment, i.e., FT10. The abiotic physical and chemical factors enhance the biodegradation of HDPE using A. terreus MF12.

A computational study on tuning the field emission and electronic properties of BN nanocones by impurity atom doping

NASA Astrophysics Data System (ADS)

Ahmadi, S.; Delir Kheirollahi Nezhad, P.; Hosseinian, A.; Vessally, E.

2018-06-01

We have inspected the effect of substituting a boron or nitrogen atom of a BN nanocone (BNNC) by two impurity atoms with lower and higher atomic numbers based on the density functional theory calculations. Our results explain the experimental observations in a molecular level. Orbital and partial density of states analyses show that the doping processes increase the electrical conductivity by creating new states within the gap of BNNC as follows: BeB > ON > CB > CN. The electron emission current from the surface of BNNC is improved after the CB and BeB dopings, and it is decreased by CN and ON dopings. The BeB and CN dopings make the BNNC a p-type semiconductor and the CB and ON dopings make it an n-type one in good agreement with the experimental results. The ON and BeB doping processes are suggested for the field emission current, and electrical conductivity enhancement, respectively.

Convolutionless Nakajima–Zwanzig equations for stochastic analysis in nonlinear dynamical systems

PubMed Central

Venturi, D.; Karniadakis, G. E.

2014-01-01

Determining the statistical properties of stochastic nonlinear systems is of major interest across many disciplines. Currently, there are no general efficient methods to deal with this challenging problem that involves high dimensionality, low regularity and random frequencies. We propose a framework for stochastic analysis in nonlinear dynamical systems based on goal-oriented probability density function (PDF) methods. The key idea stems from techniques of irreversible statistical mechanics, and it relies on deriving evolution equations for the PDF of quantities of interest, e.g. functionals of the solution to systems of stochastic ordinary and partial differential equations. Such quantities could be low-dimensional objects in infinite dimensional phase spaces. We develop the goal-oriented PDF method in the context of the time-convolutionless Nakajima–Zwanzig–Mori formalism. We address the question of approximation of reduced-order density equations by multi-level coarse graining, perturbation series and operator cumulant resummation. Numerical examples are presented for stochastic resonance and stochastic advection–reaction problems. PMID:24910519

Properties of L-ascorbic acid in water and binary aqueous mixtures of D-glucose and D-fructose at different temperatures

NASA Astrophysics Data System (ADS)

Sharma, Ravi; Thakur, R. C.; Sani, Balwinder; Kumar, Harsh

2017-12-01

Using density and sound velocity partial molar volumes, partial molar adiabatic compressibilities, partial molar expansibilities and structure of L-ascorbic acid have been determined in water and aqueous mixtures of D-glucose and D-fructose at different concentrations and temperatures. Masson's equation was used to analyze the measured data. The obtained parameters have been interpreted in terms of solute-solute and solute-solvent interactions. It is found that the L-ascorbic acid acts as structure breaker in water as well in binary studied mixtures.

Model-based approach to partial tracking for musical transcription

NASA Astrophysics Data System (ADS)

Sterian, Andrew; Wakefield, Gregory H.

1998-10-01

We present a new method for musical partial tracking in the context of musical transcription using a time-frequency Kalman filter structure. The filter is based upon a model for the evolution of a partial behavior across a wide range of pitch from four brass instruments. Statistics are computed independently for the partial attributes of frequency and log-power first differences. We present observed power spectral density shapes, total powers, and histograms, as well as least-squares approximations to these. We demonstrate that a Kalman filter tracker using this partial model is capable of tracking partials in music. We discuss how the filter structure naturally provides quality-of-fit information about the data for use in further processing and how this information can be used to perform partial track initiation and termination within a common framework. We propose that a model-based approach to partial tracking is preferable to existing approaches which generally use heuristic rules or birth/death notions over a small time neighborhood. The advantages include better performance in the presence of cluttered data and simplified tracking over missed observations.

Persistent tumor-induced osteomalacia confirmed by elevated postoperative levels of serum fibroblast growth factor-23 and 5-year follow-up of bone density changes.

PubMed

Zimering, Mark B; Caldarella, Felice A; White, Kenneth E; Econs, Michael J

2005-01-01

To describe a case of persistent tumor-induced osteomalacia, determine whether serum fibroblast growth factor-23 (FGF-23) levels postoperatively indicate incomplete tumor resection, and report lumbar spine and forearm bone mineral density (BMD) changes during 5 years of follow-up. We present clinical, radiologic, histologic, and bone densitometry data as well as serum FGF-23 levels (determined with use of a novel C-terminal enzyme-linked immunosorbent assay) from the study patient and discuss these findings in the context of previous literature. A 52-year-old man, who presented with muscle weakness and multiple fractures, was found to have low values for serum phosphorus, serum 1,25-dihydroxyvitamin D, and maximal tubular reabsorption of phosphate per glomerular filtration rate, a high level of serum alkaline phosphatase, and a normal serum concentration of parathyroid hormone, characteristic of tumor-induced osteomalacia. Magnetic resonance imaging to evaluate an abnormality of the left foot revealed a soft tissue mass, biopsy of which confirmed the presence of a benign, phosphaturic, mesenchymal tumor. The baseline serum FGF-23 level (2,050 RU/mL) was more than 17 times the upper limit of normal for adults (23 to 118 RU/mL) and decreased substantially within 1 day after partial resection of the tumor but remained above normal postoperatively. BMD changes indicated rapid substantial recovery of vertebral BMD but ongoing loss of forearm bone density. The serum FGF-23 level is high in a substantial proportion of patients with tumor-induced osteomalacia. The postoperative above normal levels of serum FGF-23 correlated with known persistence of tumor in our study patient. In a patient with normal renal function, such as our study patient, levels of serum FGF-23 studied with use of the C-terminal enzyme-linked immunosorbent assay reached their nadir within 24 hours postoperatively. This result suggests that this assay can provide clinicians with rapid prognostic information in patients with known or suspected residual tumor. BMD should be assessed at both appendicular and axial sites in patients with persistent tumor-induced osteomalacia.

Influence of thinning style on stand structure and growth in upland oaks: a 58-year case study

Treesearch

Jeffery S. Ward

2003-01-01

In 1937, a study comparing low and high thinning (partial crop tree release) was established in northwestern Connecticut. Oaks accounted for 65 percent of the crop trees that were partially released at stand ages 17, 26, and 42 years. Sawtimber trees had greater diameters, higher volumes, and higher tree grades on thinned than unmanaged plots. The higher oak density on...

Logging damage to residual trees following partial cutting in a green ash-sugarberry stand in the Mississippi Delta

Treesearch

James S. Meadows

1993-01-01

Partial cutting in bottomland hardwoods to control stand density and species composition sometimes results in logging damage to the lower bole and/or roots of residual trees. If severe, logging damage may lead to a decline in tree vigor, which may subsequently stimulate the production of epicormic branches, causing a decrease in bole quality and an eventual loss in...

Logging Damage to Residual Trees Following Partial Cutting in a Green Ash-Sugarberry Stand in the Mississippi Delta

Treesearch

James S. Meadows

1993-01-01

Partial cutting in bottomland hardwoods to control stand density and species composition sometimes results in logging damage to the lower bole and/or roots of residual trees. If severe, logging damage may lead to a decline in tree vigor, which may subsequently stimulate the production of epicormic branches, causing a decrease in bole quality and an eventual loss in...

Combining coherent hard X-ray tomographies with phase retrieval to generate three-dimensional models of forming bone

NASA Astrophysics Data System (ADS)

Bortel, Emely L.; Langer, Max; Rack, Alexander; Forien, Jean-Baptiste; Duda, Georg N.; Fratzl, Peter; Zaslansky, Paul

2017-11-01

Holotomography, a phase sensitive synchrotron-based μCT modality, is a quantitative 3D imaging method. By exploiting partial spatial X-ray coherence, bones can be imaged volumetrically with high resolution coupled with impressive density sensitivity. This tomographic method reveals the main characteristics of the important tissue compartments in forming bones, including the rapidly-changing soft tissue and the partially or fully mineralized bone regions, while revealing subtle density differences in 3D. Here we show typical results observed within the growing femur bone midshafts of healthy mice that are 1, 3, 7, 10 and 14 days old (postpartum). Our results make use of partially-coherent synchrotron radiation employing inline Fresnel-propagation in multiple tomographic datasets obtained in the imaging beamline ID19 of the ESRF. The exquisite detail creates maps of the juxtaposed soft, partially mineralized and highly mineralized bone revealing the environment in which bone cells create and shape the matrix. This high resolution 3D data is a step towards creating realistic computational models that may be used to study the dynamic processes involved in bone tissue formation and adaptation. Such data will enhance our understanding of the important biomechanical interactions directing maturation and shaping of the bone micro- and macro-geometries.

[Krigle estimation and its simulated sampling of Chilo suppressalis population density].

PubMed

Yuan, Zheming; Bai, Lianyang; Wang, Kuiwu; Hu, Xiangyue

2004-07-01

In order to draw up a rational sampling plan for the larvae population of Chilo suppressalis, an original population and its two derivative populations, random population and sequence population, were sampled and compared with random sampling, gap-range-random sampling, and a new systematic sampling integrated Krigle interpolation and random original position. As for the original population whose distribution was up to aggregative and dependence range in line direction was 115 cm (6.9 units), gap-range-random sampling in line direction was more precise than random sampling. Distinguishing the population pattern correctly is the key to get a better precision. Gap-range-random sampling and random sampling are fit for aggregated population and random population, respectively, but both of them are difficult to apply in practice. Therefore, a new systematic sampling named as Krigle sample (n = 441) was developed to estimate the density of partial sample (partial estimation, n = 441) and population (overall estimation, N = 1500). As for original population, the estimated precision of Krigle sample to partial sample and population was better than that of investigation sample. With the increase of the aggregation intensity of population, Krigel sample was more effective than investigation sample in both partial estimation and overall estimation in the appropriate sampling gap according to the dependence range.

Diel rhythmicity of lipid-body formation in a coral- Symbiodinium endosymbiosis

NASA Astrophysics Data System (ADS)

Chen, W.-N. U.; Kang, H.-J.; Weis, V. M.; Mayfield, A. B.; Jiang, P.-L.; Fang, L.-S.; Chen, C.-S.

2012-06-01

The biogenesis of intracellular lipid bodies (LBs) is dependent upon the symbiotic status between host corals and their intracellular dinoflagellates (genus Symbiodinium), though aside from this observation, little is known about LB behavior and function in this globally important endosymbiosis. The present research aimed to understand how LB formation and density are regulated in the gastrodermal tissue layer of the reef-building coral Euphyllia glabrescens. After tissue fixation and labeling with osmium tetroxide, LB distribution and density were quantified by imaging analysis of serial cryo-sections, and a diel rhythmicity was observed; the onset of solar irradiation at sunrise initiated an increase in LB density and size, which peaked at sunset. Both LB density and size then decreased to basal levels at night. On a seasonal timescale, LB density was found to be significantly positively correlated with seasonal irradiation, with highest densities found in the summer and lowest in the fall. In terms of LB lipid composition, only the concentration of wax esters, and not triglycerides or sterols, exhibited diel variability. This suggests that the metabolism and accumulation of lipids in LBs is at least partially light dependent. Ultrastructural examinations revealed that the LB wax ester concentration correlated with the number of electron-transparent inclusion bodies. Finally, there was a directional redistribution of the LB population across the gastroderm over the diel cycle. Collectively, these data reveal that coral gastrodermal LBs vary in composition and intracellular location over diel cycles, features which may shed light on their function within this coral-dinoflagellate mutualism.

Elementary diagrams in nuclear and neutron matter

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

Wiringa, R.B.

1995-08-01

Variational calculations of nuclear and neutron matter are currently performed using a diagrammatic cluster expansion with the aid of nonlinear integral equations for evaluating expectation values. These are the Fermi hypernetted chain (FHNC) and single-operator chain (SOC) equations, which are a way of doing partial diagram summations to infinite order. A more complete summation can be made by adding elementary diagrams to the procedure. The simplest elementary diagrams appear at the four-body cluster level; there is one such E{sub 4} diagram in Bose systems, but 35 diagrams in Fermi systems, which gives a level of approximation called FHNC/4. We developedmore » a novel technique for evaluating these diagrams, by computing and storing 6 three-point functions, S{sub xyz}(r{sub 12}, r{sub 13}, r{sub 23}), where xyz (= ccd, cce, ddd, dde, dee, or eee) denotes the exchange character at the vertices 1, 2, and 3. All 35 Fermi E{sub 4} diagrams can be constructed from these 6 functions and other two-point functions that are already calculated. The elementary diagrams are known to be important in some systems like liquid {sup 3}He. We expect them to be small in nuclear matter at normal density, but they might become significant at higher densities appropriate for neutron star calculations. This year we programmed the FHNC/4 contributions to the energy and tested them in a number of simple model cases, including liquid {sup 3}He and Bethe`s homework problem. We get reasonable, but not exact agreement with earlier published work. In nuclear and neutron matter with the Argonne v{sub 14} interaction these contributions are indeed small corrections at normal density and grow to only 5-10 MeV/nucleon at 5 times normal density.« less

Influence of stretching and density contrasts on the chemical evolution of continental magmas: An example from the Ivrea-Verbano Zone

USGS Publications Warehouse

Sinigoi, S.; Quick, J.E.; Mayer, A.; Budahn, J.

1996-01-01

The southern Ivrea-Verbano Zone of the Italian Western Alps contains a huge mafic complex that intruded high-grade metamorphic rocks while they were resident in the lower crust. Geologic mapping and chemical variations of the igneous body were used to study the evolution of underplated crust. Slivers of crustal rocks (septa) interlayered with igneous mafic rocks are concentrated in a narrow zone deep in the complex (Paragneiss-bearing Belt) and show evidence of advanced degrees of partial melting. Variations of rare-earth-element patterns and Sr isotope composition of the igneous rocks across the sequence are consistent with increasing crustal contamination approaching the septa. Therefore, the Paragneiss-bearing Belt is considered representative of an "assimilation region" where in-situ interaction between mantle- and crust-derived magmas resulted in production of hybrid melts. Buoyancy caused upwards migration of the hybrid melts that incorporated the last septa and were stored at higher levels, feeding the Upper Mafic Complex. Synmagmatic stretching of the assimilation region facilitated mixing and homogenization of melts. Chemical variations of granitoids extracted from the septa show that deep septa are more depleted than shallow ones. This suggests that the first incorporated septa were denser than the later ones, as required by the high density of the first-injected mafic magmas. It is inferred that density contrasts between mafic melts and crustal rocks play a crucial role for the processes of contamination of continental magmas. In thick under- plated crust, the extraction of early felsic/hybrid melts from the lower crust may be required to increase the density of the lower crust and to allow the later mafic magmas to penetrate higher crustal levels.

Online sequential Monte Carlo smoother for partially observed diffusion processes

NASA Astrophysics Data System (ADS)

Gloaguen, Pierre; Étienne, Marie-Pierre; Le Corff, Sylvain

2018-12-01

This paper introduces a new algorithm to approximate smoothed additive functionals of partially observed diffusion processes. This method relies on a new sequential Monte Carlo method which allows to compute such approximations online, i.e., as the observations are received, and with a computational complexity growing linearly with the number of Monte Carlo samples. The original algorithm cannot be used in the case of partially observed stochastic differential equations since the transition density of the latent data is usually unknown. We prove that it may be extended to partially observed continuous processes by replacing this unknown quantity by an unbiased estimator obtained for instance using general Poisson estimators. This estimator is proved to be consistent and its performance are illustrated using data from two models.

Submillimeter observations of OH and CH in M42

NASA Technical Reports Server (NTRS)

Viscuso, P. J.; Stacy, G. J.; Fuller, C. E.; Kurtz, N. T.; Harwit, M.

1985-01-01

The (sup 2) pi sub 1/2 (J = 3/2 to 1/2) transitions of OH at 163.12 and 163.40 micro m have been detected and upper limits have been obtained for the (sup 2) pi sub 3/2 (J = 3/2 to 1/2) transitions of CH at 149.09 and 149.39 micro m, in observations of the Kleinmann-Low Nebula of Orion. All four flux levels lie between 1 and 1.2 x 10 to the 17th power/sq.cm. The OH lines are bright when compared to the lower, (sup 2) pi sub 3/2 (J = 5/2 to 3/2) fluxes reported and imply that the 119 micro m emission observed is partially self-absorbed. The combined results provide strong constraints. Taken together with existing data on molecular hydrogen and CO and recent data on other OH transition, they suggest OH emission from post-shock regions at temperatures T approx 1000 k, densities approx. 7 x 10 to the 6th powr/cu cm N sub OH approx 80/cu cm optically thick for the (sup 2) pi sub 3/2 (J = 5/2 to 3/2), 119 micro m but only partially self-absorbing in the (J = 7/2 to 3/2), 84 micro m transitions over a Doppler velocity bandwidth of 30 km/sec. The OH column density is N sub OH approx 4 x 10 to the 16th powr/sq cm. in the emitting regions which occupy a fraction of approx 0.1 of a 1' x 1' field of view centered on the Becklin-Neugebauer source. The CO (J = 31 to 30), 84 micro m transition appears to lie sufficiently close to one of the 84 micro m OH line components to be partially absorbed as well, through a Bowen-type mechanism.

Growth-suppressing and algicidal properties of an extract from Arundo donax, an invasive riparian plant, against Prymnesium parvum, an invasive harmful alga.

PubMed

Patiño, Reynaldo; Rashel, Rakib H; Rubio, Amede; Longing, Scott

2018-01-01

This study examined the ability of acidic and neutral/alkaline fractions of a methanolic extract from giant reed (Arundo donax) and of two of its constituents, gramine and skatole, to inhibit growth of the ichthyotoxic golden alga (Prymnesium parvum) in batch culture. For this study, growth suppression was defined as inhibition of maximum cell density, algicidal activity as early occurrence of negative growth, and algistatic activity as lack of net growth. The acidic fraction did not affect algal growth. The neutral/alkaline fraction showed growth-suppressing and algicidal activities but no signs of algistatic activity - namely, cells in cultures surviving a partial-algicidal exposure concentration (causing transient negative growth) were later able to initiate positive growth but at higher concentrations, algicidal activity was full and irreversible. Gramine suppressed growth more effectively than skatole and at the highest concentration tested, gramine also showed partial-algicidal and algistatic activity. While the partial-algicidal activities of the neutral/alkaline fraction and of gramine were short-lived (≤6days) and thus may share similar mechanisms, algistatic activity was unique to gramine and persisted for >3 weeks. Given gramine's reported concentration in the neutral/alkaline fraction, its corresponding level of algicidal activity is much lower than the fraction's suggesting the latter contains additional potent algicides. Inhibition of maximum cell density by all test compounds was associated with reductions in exponential growth rate, and in the case of the neutral/alkaline fraction and gramine also reductions in early (pre-exponential) growth. These results indicate that giant reed is a potential source of natural products to control golden alga blooms. Giant reed is an invasive species in North America, thus also providing incentive for research into strategies to couple management efforts for both species. Published by Elsevier B.V.

Growth-suppressing and algicidal properties of an extract from Arundo donax, an invasive riparian plant, against Prymnesium parvum, an invasive harmful alga

USGS Publications Warehouse

Patino, Reynaldo; Rashel, Rakib H.; Rubio, Amede; Longing, Scott

2018-01-01

This study examined the ability of acidic and neutral/alkaline fractions of a methanolic extract from giant reed (Arundo donax) and of two of its constituents, gramine and skatole, to inhibit growth of the ichthyotoxic golden alga (Prymnesium parvum) in batch culture. For this study, growth suppression was defined as inhibition of maximum cell density, algicidal activity as early occurrence of negative growth, and algistatic activity as lack of net growth. The acidic fraction did not affect algal growth. The neutral/alkaline fraction showed growth-suppressing and algicidal activities but no signs of algistatic activity – namely, cells in cultures surviving a partial-algicidal exposure concentration (causing transient negative growth) were later able to initiate positive growth but at higher concentrations, algicidal activity was full and irreversible. Gramine suppressed growth more effectively than skatole and at the highest concentration tested, gramine also showed partial-algicidal and algistatic activity. While the partial-algicidal activities of the neutral/alkaline fraction and of gramine were short-lived (≤6 days) and thus may share similar mechanisms, algistatic activity was unique to gramine and persisted for >3 weeks. Given gramine’s reported concentration in the neutral/alkaline fraction, its corresponding level of algicidal activity is much lower than the fraction’s suggesting the latter contains additional potent algicides. Inhibition of maximum cell density by all test compounds was associated with reductions in exponential growth rate, and in the case of the neutral/alkaline fraction and gramine also reductions in early (pre-exponential) growth. These results indicate that giant reed is a potential source of natural products to control golden alga blooms. Giant reed is an invasive species in North America, thus also providing incentive for research into strategies to couple management efforts for both species.

Equatorial distributions of energetic ion moments in Saturn's magnetosphere using Cassini/MIMI measurements

NASA Astrophysics Data System (ADS)

Dialynas, K.; Roussos, E.; Regoli, L.; Paranicas, C.; Krimigis, S. M.; Kane, M.; Mitchell, D. G.; Hamilton, D. C.

2016-12-01

We use kappa distribution fits to combined Charge Energy Mass Spectrometer (CHEMS, 3 to 236 keV/e), Low Energy Magnetosphere Measurements System (LEMMS, 0.024 < E < 18 MeV), and Ion Neutral Camera (INCA, 5.2 to >220 keV for H+) proton and singly ionized energetic ion spectra to calculate the >20 keV energetic ion moments inside Saturn's magnetosphere. Using a realistic magnetic field model (Khurana et al. 2007) and data from the entire Cassini mission to date (2004-2016), we map the ion measurements to the equatorial plane and via the modeled kappa distribution spectra we produce the equatorial distributions of all ion integral moments, focusing on partial density, integral intensity, partial pressure, integral energy intensity; as well as the characteristic energy (EC=IE/In), Temperature and κ-index of these ions as a function of Local Time (00:00 to 24:00 hrs) and L-Shell (5-20). A modified version of the semi-empirical Roelof and Skinner [2000] model is then utilized to retrieve the equatorial H+ and O+ pressure, density and temperature in Saturn's magnetosphere in both local time and L-shell. We find that a) although the H+ and O+ partial pressures and densities are nearly comparable, the >20 keV protons have higher number and energy intensities at all radial distances (L>5) and local times; b) the 12

Enhanced Scattering of Diffuse Ions on Front of the Earth's Quasi-Parallel Bow Shock: a Case Study

NASA Astrophysics Data System (ADS)

Kis, A.; Matsukiyo, S.; Otsuka, F.; Hada, T.; Lemperger, I.; Dandouras, I. S.; Barta, V.; Facsko, G. I.

2017-12-01

In the analysis we present a case study of three energetic upstream ion events at the Earth's quasi-parallel bow shock based on multi-spacecraft data recorded by Cluster. The CIS-HIA instrument onboard Cluster provides partial energetic ion densities in 4 energy channels between 10 and 32 keV.The difference of the partial ion densities recorded by the individual spacecraft at various distances from the bow shock surface makes possible the determination of the spatial gradient of energetic ions.Using the gradient values we determined the spatial profile of the energetic ion partial densities as a function of distance from the bow shock and we calculated the e-folding distance and the diffusion coefficient for each event and each ion energy range. Results show that in two cases the scattering of diffuse ions takes place in a normal way, as "by the book", and the e-folding distance and diffusion coefficient values are comparable with previous results. On the other hand, in the third case the e-folding distance and the diffusion coefficient values are significantly lower, which suggests that in this case the scattering process -and therefore the diffusive shock acceleration (DSA) mechanism also- is much more efficient. Our analysis provides an explanation for this "enhanced" scattering process recorded in the third case.

Asymptotic behavior of distributions of mRNA and protein levels in a model of stochastic gene expression

NASA Astrophysics Data System (ADS)

Bobrowski, Adam; Lipniacki, Tomasz; Pichór, Katarzyna; Rudnicki, Ryszard

2007-09-01

The paper is devoted to a stochastic process introduced in the recent paper by Lipniacki et al. [T. Lipniacki, P. Paszek, A. Marciniak-Czochra, A.RE Brasier, M. Kimmel, Transcriptional stochasticity in gene expression, JE Theor. Biol. 238 (2006) 348-367] in modelling gene expression in eukaryotes. Starting from the full generator of the process we show that its distributions satisfy a (Fokker-Planck-type) system of partial differential equations. Then, we construct a c0 Markov semigroup in L1 space corresponding to this system. The main result of the paper is asymptotic stability of the involved semigroup in the set of densities.

Mass loss of a TEOS-coated, reinforced carbon-carbon composite subjected to a simulted shuttle entry environment

NASA Technical Reports Server (NTRS)

Stroud, C. W.; Rummler, D. R.

1980-01-01

Coated, reinforced carbon-carbon (RCC) is used for the leading edges of the space shuttle. The mass loss characteristics of RCC specimens coated with tetraethyl orthosilicate (TEOS) were determine for conditions which simulated the environment expected at the lug attachment area of the leading edge. Mission simulation included simultaneous application of load, temperature, and oxygen partial pressure. Maximum specimen temperature was 900 K (1160 F). Specimens were exposed for up to 80 simulated missions. Stress levels up to 6.8 MPa (980 psi) did not significantly affect the mass loss characteristics of the TEOS-coated RCC material. Mass loss was correlated with the bulk density of the specimens.

Emerald ash borer (Coleoptera: Buprestidae) attraction to stressed or baited ash trees.

PubMed

McCullough, Deborah G; Poland, Therese M; Anulewicz, Andrea C; Cappaert, David

2009-12-01

Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), has killed millions of ash (Fraxinus sp.) trees in North America since its discovery in Michigan in 2002. Efficient methods to detect low-density A. planipennis populations remain a critical priority for regulatory and resource management agencies. We compared the density of adult A. planipennis captured on sticky bands and larval density among ash trees that were girdled for 1 or 2 yr, wounded, exposed to the stress-elicitor methyl jasmonate, baited with Manuka oil lures, or left untreated. Studies were conducted at four sites in 2006 and 2007, where A. planipennis densities on untreated trees ranged from very low to moderate. In 2006, 1-yr girdled trees captured significantly more adult A. planipennis and had higher larval densities than untreated control trees or trees treated with methyl jasmonate or Manuka oil. Open-grown trees captured significantly more A. planipennis beetles than partially or fully shaded trees. In 2007, A. planipennis population levels and captures of adult A. planipennis were substantially higher than in 2006. The density of adults captured on sticky bands did not differ significantly among canopy exposure classes or treatments in 2007. Larval density was significantly higher in untreated, wounded, and 1-yr girdled trees (girdled in 2007) than in 2-yr girdled trees (girdled in 2006), where most phloem was consumed by A. planipennis larvae the previous year. A total of 36 trees (32 in 2006, 4 in 2007) caught no beetles, but 16 of those trees (13 in 2006, 3 in 2007) had A. planipennis larvae. In 2006, there was a positive linear relationship between the density of adults captured on sticky bands and larval density in trees. Our results show that freshly girdled and open grown trees were most attractive to A. planipennis, especially at low-density sites. If girdled trees are used for A. planipennis detection or survey, debarking trees to locate larval galleries is crucial.

Competition between harvester ants and rodents in the cold desert

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

Landeen, D.S.; Jorgensen, C.D.; Smith, H.D.

1979-09-30

Local distribution patterns of three rodent species (Perognathus parvus, Peromyscus maniculatus, Reithrodontomys megalotis) were studied in areas of high and low densities of harvester ants (Pogonomyrmex owyheei) in Raft River Valley, Idaho. Numbers of rodents were greatest in areas of high ant-density during May, but partially reduced in August; whereas, the trend was reversed in areas of low ant-density. Seed abundance was probably not the factor limiting changes in rodent populations, because seed densities of annual plants were always greater in areas of high ant-density. Differences in seasonal population distributions of rodents between areas of high and low ant-densities weremore » probably due to interactions of seed availability, rodent energetics, and predation.« less

Human activities cause distinct dissolved organic matter composition across freshwater ecosystems.

PubMed

Williams, Clayton J; Frost, Paul C; Morales-Williams, Ana M; Larson, James H; Richardson, William B; Chiandet, Aisha S; Xenopoulos, Marguerite A

2016-02-01

Dissolved organic matter (DOM) composition in freshwater ecosystems is influenced by the interactions among physical, chemical, and biological processes that are controlled, at one level, by watershed landscape, hydrology, and their connections. Against this environmental template, humans may strongly influence DOM composition. Yet, we lack a comprehensive understanding of DOM composition variation across freshwater ecosystems differentially affected by human activity. Using optical properties, we described DOM variation across five ecosystem groups of the Laurentian Great Lakes region: large lakes, Kawartha Lakes, Experimental Lakes Area, urban stormwater ponds, and rivers (n = 184 sites). We determined how between ecosystem variation in DOM composition related to watershed size, land use and cover, water quality measures (conductivity, dissolved organic carbon (DOC), nutrient concentration, chlorophyll a), and human population density. The five freshwater ecosystem groups had distinctive DOM composition from each other. These significant differences were not explained completely through differences in watershed size nor spatial autocorrelation. Instead, multivariate partial least squares regression showed that DOM composition was related to differences in human impact across freshwater ecosystems. In particular, urban/developed watersheds with higher human population densities had a unique DOM composition with a clear anthropogenic influence that was distinct from DOM composition in natural land cover and/or agricultural watersheds. This nonagricultural, human developed impact on aquatic DOM was most evident through increased levels of a microbial, humic-like parallel factor analysis component (C6). Lotic and lentic ecosystems with low human population densities had DOM compositions more typical of clear water to humic-rich freshwater ecosystems but C6 was only present at trace to background levels. Consequently, humans are strongly altering the quality of DOM in waters nearby or flowing through highly populated areas, which may alter carbon cycles in anthropogenically disturbed ecosystems at broad scales. © 2015 John Wiley & Sons Ltd.

Endogenous Sex Steroid Hormones, Lipid Subfractions, and Ectopic Adiposity in Asian Indians.

PubMed

Kim, Catherine; Kong, Shengchun; Krauss, Ronald M; Stanczyk, Frank Z; Reddy, Srinivasa T; Needham, Belinda L; Kanaya, Alka M

2015-12-01

Estradiol, testosterone (T), and sex hormone binding globulin (SHBG) levels are associated with lipid subfractions in men and women. Our objective was to determine if associations are independent from adipose tissue area among Asian Indians. We used data from 42 women and 57 Asian Indian men who did not use exogenous steroids or lipid-lowering medications. Lipoprotein subfractions including low-density lipoprotein cholesterol (LDL), very low-density lipoprotein cholesterol (VLDL), and intermediate density lipoprotein (IDL) were assessed by ion mobility spectrometry. Intra-abdominal adiposity was assessed by computed tomography. Multivariable regression models estimated the association between sex hormones with lipoprotein subfractions before and after adjustment for adiposity. Among women, lower logSHBG levels were associated with smaller logLDL particle size and higher logtriglycerides, logVLDL, and logIDL, although these associations were attenuated with adjustment for visceral adiposity in particular. Among women, lower logSHBG levels was significantly associated with lower logmedium LDL and logsmall LDL concentrations even after consideration of visceral and hepatic adiposity and insulin resistance as represented by the homeostasis model assessment of insulin resistance (HOMA-IR). Among men, lower logSHBG was also associated with smaller logLDL peak diameter size and higher logtriglycerides and logVLDL, even after adjustment for HOMA-IR and adiposity. Relationships between sex steroids and lipid subfractions were not significant among women. Among men, higher total testosterone was associated with higher logHDL and logLDL particle size, and lower logtriglycerides and logVLDL, but these associations were partially attenuated with adjustment for adiposity and HOMA-IR. Among Asian Indians, SHBG is associated with more favorable lipid subfraction concentrations, independent of hepatic and visceral fat.

Human activities cause distinct dissolved organic matter composition across freshwater ecosystems

USGS Publications Warehouse

Williams, Clayton J.; Frost, Paul C.; Morales-Williams, Ana M.; Larson, James H.; Richardson, William B.; Chiandet, Aisha S.; Xenopoulos, Marguerite A.

2016-01-01

Dissolved organic matter (DOM) composition in freshwater ecosystems is influenced by interactions between physical, chemical, and biological processes that are controlled, at one level, by watershed landscape, hydrology, and their connections. Against this environmental template, humans may strongly influence DOM composition. Yet, we lack a comprehensive understanding of DOM composition variation across freshwater ecosystems differentially affected by human activity. Using optical properties, we described DOM variation across five ecosystem groups of the Laurentian Great Lakes Region: large lakes, Kawartha Lakes, Experimental Lakes Area, urban stormwater ponds, and rivers (n = 184 sites). We determined how between ecosystem variation in DOM composition related to watershed size, land use and cover, water quality measures (conductivity, dissolved organic carbon (DOC), nutrient concentration, chlorophyll a), and human population density. The five freshwater ecosystem groups had distinctive DOM composition from each other. These significant differences were not explained completely through differences in watershed size nor spatial autocorrelation. Instead, multivariate partial least squares regression showed that DOM composition was related to differences in human impact across freshwater ecosystems. In particular, urban/developed watersheds with higher human population densities had a unique DOM composition with a clear anthropogenic influence that was distinct from DOM composition in natural land cover and/or agricultural watersheds. This nonagricultural, human developed impact on aquatic DOM was most evident through increased levels of a microbial, humic-like parallel factor analysis component (C6). Lotic and lentic ecosystems with low human population densities had DOM compositions more typical of clear water to humic-rich freshwater ecosystems but C6 was only present at trace to background levels. Consequently, humans are strongly altering the quality of DOM in waters nearby or flowing through highly populated areas, which may alter carbon cycles in anthropogenically disturbed ecosystems at broad scales.

Lipid-lowering effects of TAK-475, a squalene synthase inhibitor, in animal models of familial hypercholesterolemia.

PubMed

Amano, Yuichiro; Nishimoto, Tomoyuki; Tozawa, Ryu ichi; Ishikawa, Eiichiro; Imura, Yoshimi; Sugiyama, Yasuo

2003-04-11

The lipid-lowering effects of 1-[2-[(3R,5S)-1-(3-acetoxy-2,2-dimethylpropyl)-7-chloro-1,2,3,5-tetrahydro-2-oxo-5-(2,3-dimethoxyphenyl)-4,1-benzoxazepine-3-yl] acetyl] piperidin-4-acetic acid (TAK-475), a novel squalene synthase inhibitor, were examined in two models of familial hypercholesterolemia, low-density lipoprotein (LDL) receptor knockout mice and Watanabe heritable hyperlipidemic (WHHL) rabbits. Two weeks of treatment with TAK-475 in a diet admixture (0.02% and 0.07%; approximately 30 and 110 mg/kg/day, respectively) significantly lowered plasma non-high-density lipoprotein (HDL) cholesterol levels by 19% and 41%, respectively, in homozygous LDL receptor knockout mice. The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, simvastatin and atorvastatin (in 0.02% and 0.07% admixtures), also reduced plasma levels of non-HDL cholesterol. In homozygous WHHL rabbits, 4 weeks of treatment with TAK-475 (0.27%; approximately 100 mg/kg/day) lowered plasma total cholesterol, triglyceride and phospholipid levels by 17%, 52% and 26%, respectively. In Triton WR-1339-treated rabbits, TAK-475 inhibited to the same extent the rate of secretion from the liver of the cholesterol, triglyceride and phospholipid components of very-low-density lipoprotein (VLDL). These results suggest that the lipid-lowering effects of TAK-475 in WHHL rabbits are based partially on the inhibition of secretion of VLDL from the liver. TAK-475 had no effect on plasma aspartate aminotransferase and alanine aminotransferase activities. Thus, the squalene synthase inhibitor TAK-475 revealed lipid-lowering effects in both LDL receptor knockout mice and WHHL rabbits.

Adsorption and dissociation of molecular hydrogen on the (0001) surface of double hexagonal close packed americium

NASA Astrophysics Data System (ADS)

Dholabhai, P. P.; Ray, A. K.

2009-01-01

Hydrogen molecule adsorption on the (0001) surface of double hexagonal packed americium has been studied in detail within the framework of density functional theory using a full-potential all-electron linearized augmented plane wave plus local orbitals method (FP-L/APW+lo). Weak molecular hydrogen adsorptions were observed. Adsorption energies were optimized with respect to the distance of the adsorbates from the surface for three approach positions at three adsorption sites, namely t1 (one-fold top), b2 (two-fold bridge), and h3 (three-fold hollow) sites. Adsorption energies were computed at the scalar-relativistic level (no spin-orbit coupling NSOC) and at the fully relativistic level (with spin-orbit coupling SOC). The most stable configuration corresponds to a horizontal adsorption with the molecular approach being perpendicular to a lattice vector. The surface coverage is equivalent to one-fourth of a monolayer (ML), with the adsorption energies at the NSOC and SOC theoretical levels being 0.0997 eV and 0.1022 eV, respectively. The respective distance of the hydrogen molecule from the surface and hydrogen-hydrogen distance was found to be 2.645 Å and 0.789 Å, respectively. The work functions decreased and the net magnetic moments remained almost unchanged in all cases compared with the corresponding quantities of bare dhcp Am (0001) surface. The adsorbate-substrate interactions have been analyzed in detail using the partial charges inside the muffin-tin spheres, difference charge density distributions, and the local density of states. The effects of adsorption on the Am 5f electron localization-delocalization characteristics have been discussed. Reaction barrier for the dissociation of hydrogen molecule has been presented.

Modulated two-dimensional charge-carrier density in LaTiO3-layer-doped LaAlO3/SrTiO3 heterostructure.

PubMed

Nazir, Safdar; Bernal, Camille; Yang, Kesong

2015-03-11

The highly mobile two-dimensional electron gas (2DEG) formed at the polar/nonpolar LaAlO3/SrTiO3 (LAO/STO) heterostructure (HS) is a matter of great interest because of its potential applications in nanoscale solid-state devices. To realize practical implementation of the 2DEG in device design, desired physical properties such as tuned charge carrier density and mobility are necessary. In this regard, polar perovskite-based transition metal oxides can act as doping layers at the interface and are expected to tune the electronic properties of 2DEG of STO-based HS systems dramatically. Herein, we investigated the doping effects of LaTiO3(LTO) layers on the electronic properties of 2DEG at n-type (LaO)(+1)/(TiO2)(0) interface in the LAO/STO HS using spin-polarized density functional theory calculations. Our results indicate an enhancement of orbital occupation near the Fermi energy, which increases with respect to the number of LTO unit cells, resulting in a higher charge carrier density of 2DEG than that of undoped system. The enhanced charge carrier density is attributed to an extra electron introduced by the Ti 3d(1) orbitals from the LTO dopant unit cells. This conclusion is consistent with the recent experimental findings (Appl. Phys. Lett. 2013, 102, 091601). Detailed charge density and partial density of states analysis suggests that the 2DEG in the LTO-doped HS systems primarily comes from partially occupied dyz and dxz orbitals.

Power Electronic Transformer based Three-Phase PWM AC Drives

NASA Astrophysics Data System (ADS)

Basu, Kaushik

A Transformer is used to provide galvanic isolation and to connect systems at different voltage levels. It is one of the largest and most expensive component in most of the high voltage and high power systems. Its size is inversely proportional to the operating frequency. The central idea behind a power electronic transformer (PET) also known as solid state transformer is to reduce the size of the transformer by increasing the frequency. Power electronic converters are used to change the frequency of operation. Steady reduction in the cost of the semiconductor switches and the advent of advanced magnetic materials with very low loss density and high saturation flux density implies economic viability and feasibility of a design with high power density. Application of PET is in generation of power from renewable energy sources, especially wind and solar. Other important application include grid tied inverters, UPS e.t.c. In this thesis non-resonant, single stage, bi-directional PET is considered. The main objective of this converter is to generate adjustable speed and magnitude pulse width modulated (PWM) ac waveforms from an ac or dc grid with a high frequency ac link. The windings of a high frequency transformer contains leakage inductance. Any switching transition of the power electronic converter connecting the inductive load and the transformer requires commutation of leakage energy. Commutation by passive means results in power loss, decrease in the frequency of operation, distortion in the output voltage waveform, reduction in reliability and power density. In this work a source based partially loss-less commutation of leakage energy has been proposed. This technique also results in partial soft-switching. A series of converters with novel PWM strategies have been proposed to minimize the frequency of leakage inductance commutation. These PETs achieve most of the important features of modern PWM ac drives including 1) Input power factor correction, 2) Common-mode voltage suppression at the load end, 3) High quality output voltage waveform (comparable to conventional space vector PWM modulated two level inverter) and 4) Minimization of output voltage loss, common-mode voltage switching and distortion of the load current waveform due to leakage inductance commutation. All of the proposed topologies along with the proposed control schemes have been analyzed and simulated in MATLABSimulink. A hardware prototype has been fabricated and tested. The simulation and experimental results verify the operation and advantages of the proposed topologies and their control.

Modeling tree crown dynamics with 3D partial differential equations.

PubMed

Beyer, Robert; Letort, Véronique; Cournède, Paul-Henry

2014-01-01

We characterize a tree's spatial foliage distribution by the local leaf area density. Considering this spatially continuous variable allows to describe the spatiotemporal evolution of the tree crown by means of 3D partial differential equations. These offer a framework to rigorously take locally and adaptively acting effects into account, notably the growth toward light. Biomass production through photosynthesis and the allocation to foliage and wood are readily included in this model framework. The system of equations stands out due to its inherent dynamic property of self-organization and spontaneous adaptation, generating complex behavior from even only a few parameters. The density-based approach yields spatially structured tree crowns without relying on detailed geometry. We present the methodological fundamentals of such a modeling approach and discuss further prospects and applications.

Mean field games with congestion

NASA Astrophysics Data System (ADS)

Achdou, Yves; Porretta, Alessio

2018-03-01

We consider a class of systems of time dependent partial differential equations which arise in mean field type models with congestion. The systems couple a backward viscous Hamilton-Jacobi equation and a forward Kolmogorov equation both posed in $(0,T)\\times (\\mathbb{R}^N /\\mathbb{Z}^N)$. Because of congestion and by contrast with simpler cases, the latter system can never be seen as the optimality conditions of an optimal control problem driven by a partial differential equation. The Hamiltonian vanishes as the density tends to $+\\infty$ and may not even be defined in the regions where the density is zero. After giving a suitable definition of weak solutions, we prove the existence and uniqueness results of the latter under rather general assumptions. No restriction is made on the horizon $T$.

Shock vaporization and the accretion of the icy satellites of Jupiter and Saturn

NASA Technical Reports Server (NTRS)

Ahrens, T. J.; Okeefe, J. D.

1984-01-01

The role of impact vaporization acting during the formation of the Jovian and Saturnian satellites is examined in an attempt to explain the observed density in terms of composition of these rock and ice objects. A hypothesis is examined which states that the smaller satellites of Saturn having mean densities in the 1.1 to 1.4 Mg/cu m range represent primordial accreted planetesimal condensates formed in the proto-Jovian and Saturnian accretionary planetary discs. These densities are in the range expected for water-ice/silicate mixtures constrained in the solar values of O/Si and O/Mg atomic ratios. It is demonstrated that if the large satellites accreted from the same group of planetesimals which formed the small Saturnian satellites impact vaporization of water upon accretion in a porous regolith, at low H2O partial pressure, can account for the increase in mean planetesimal density from 1.6 Mg/cu m (43% H2O + 57% silicate) to a mean planetary density of 1.9 Mg/cu m for Ganymedean-sized water silicate objects. If impact volatilization of initially porous planetesimals is assumed, it can be demonstrated starting with planetesimals composed of 54% H2O and 40% silicate partial devolatilization upon accretion will yield a Ganymede-sized planet, having a radius of 2600 km and a density of 1.85 kg/cu m, similar to that of Ganymede, Callisto, and Titan.

Catalysis of partial chiral symmetry restoration by Δ matter

NASA Astrophysics Data System (ADS)

Takeda, Yusuke; Kim, Youngman; Harada, Masayasu

2018-06-01

We study the phase structure of dense hadronic matter including Δ (1232 ) as well as N (939 ) based on the parity partner structure, where the baryons have their chiral partners with a certain amount of chiral invariant masses. We show that, in symmetric matter, Δ enters into matter in the density region of about one to four times normal nuclear matter density, ρB˜1 -4 ρ0 . The onset density of Δ matter depends on the chiral invariant mass of Δ ,mΔ 0 : As mΔ 0 increases, the onset density becomes bigger. The stable Δ -nucleon matter is realized for ρB≳1.5 ρ0 , i.e., the phase transition from nuclear matter to Δ -nucleon matter is of first order for small mΔ 0, and it is of second order for large mΔ 0. We find that, associated with the phase transition, the chiral condensate changes very rapidly; i.e., the chiral symmetry restoration is accelerated by Δ matter. As a result of the accelerations, there appear N*(1535 ) and Δ (1700 ) , which are the chiral partners to N (939 ) and Δ (1232 ) , in high-density matter, signaling the partial chiral symmetry restoration. Furthermore, we find that complete chiral symmetry restoration itself is delayed by Δ matter. We also calculate the effective masses, pressure, and symmetry energy to study how the transition to Δ matter affects such physical quantities. We observe that the physical quantities change drastically at the transition density.

Impact of fetal chromosomal disorders on maternal blood metabolome: toward new biomarkers?

PubMed

Pinto, Joana; Almeida, Lara Monteiro; Martins, Ana Sofia; Duarte, Daniela; Domingues, Maria Rosário Marques; Barros, António Sousa; Galhano, Eulália; Pita, Cristina; Almeida, Maria do Céu; Carreira, Isabel Marques; Gil, Ana Maria

2015-12-01

This study aimed at determining the relationship between fetal chromosomal disorders (CDs), including trisomy 21 (T21), and on first- and second-trimester maternal blood plasma, to identify the time-course metabolic adaptations to the conditions and the possible new plasma biomarkers. Furthermore, a definition of a joint circulatory (plasma) and excretory (urine) metabolic description of second-trimester CDs was sought. Plasma was obtained for 119 pregnant women: 74 controls and 45 CD cases, including 22 T21 cases. Plasma and lipid extracts (for T21 only) were analyzed by nuclear magnetic resonance spectroscopy, and data were handled by variable selection and multivariate analysis. Correlation analysis was used on a concatenated plasma/urine matrix descriptive of second-trimester CD, based on previously obtained urine data. CD cases were accompanied by enhanced lipid β-oxidation (increased ketone bodies) and underutilization of glucose, pyruvate, and citrate. Lower circulating high-density lipoprotein levels were noted, along with changes in the proline and methanol in the first trimester, and also the urea, creatinine, acetate, and low-density lipoprotein plus very low-density lipoprotein in the second trimester and the different urea and creatinine levels, suggesting fetal renal dysfunction. In terms of plasma composition, T21 cases were indistinguishable from other CDs in the first trimester, whereas in the second trimester, increased methanol and albumin may be T21 specific. Furthermore, first-trimester lipid extracts of T21 showed decreased levels of 18:2 fatty acids, whereas in the second trimester, lower levels of 20:4 and 22:6 fatty acids were noted, possibly indicative of inflammation mechanisms. In both trimesters, high classification rates for CDs (88-89%) and T21 (85-92%) generally relied on variable selection of nuclear magnetic resonance data. Plasma/urine correlations confirmed most metabolic deviations and unveiled possible new ones regarding low-density lipoprotein plus very low-density lipoprotein, sugar, and gut-microflora metabolisms. This work partially confirmed previously reported data on first-trimester T21 and provided additional information on time-course metabolic changes accompanying CD and T21, in particular regarding plasma lipid composition. These results demonstrate the potential of plasma metabolomics in monitoring and characterizing CD cases; however, validation in larger cohorts is desirable. Copyright © 2015 Elsevier Inc. All rights reserved.

Evidence of partial melting beneath a continental margin: case of Dhofar, in the Northeast Gulf of Aden (Sultanate of Oman)

NASA Astrophysics Data System (ADS)

Basuyau, C.; Tiberi, C.; Leroy, S.; Stuart, G.; Al-Lazki, A.; Al-Toubi, K.; Ebinger, C.

2010-02-01

Gravity data and P-wave teleseismic traveltime residuals from 29 temporary broad-band stations spread over the northern margin of the Gulf of Aden (Dhofar region, Oman) were used to image lithospheric structure. We apply a linear relationship between density and velocity to provide consistent density and velocity models from mid-crust down to about 250 km depth. The accuracy of the resulting models is investigated through a series of synthetic tests. The analysis of our resulting models shows: (1) crustal heterogeneities that match the main geological features at the surface; (2) the gravity edge effect and disparity in anomaly depth locations for layers at 20 and 50 km; (3) two low-velocity anomalies along the continuation of Socotra-Hadbeen and Alula-Fartak fracture zones between 60 and 200 km depth; and (4) evidence for partial melting (3-6 per cent) within these two negative anomalies. We discuss the presence of partial melting in terms of interaction between the Sheba ridge melts and its along-axis segmentation.

Recent research on stishovite: Hugoniot and partial release Z experiments and DFT EOS calculations.

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

Furnish, Michael D.; Shulenburger, Luke; Desjarlais, Michael

We have conducted a series of ride-along experiments on the Z facility to ascertain the Hugoniot of silica centered in the stishovite phase over a range 0.4 - 1.0 TPa, together with partial release states produced at the interface between the sample and a fused silica window. The stishovite samples were synthesized in a large-volume multi-anvil press at 15 GPa and 1773 K, with an initial density of 4.29 gm/cc. The new Z experiments on stishovite fill in a gap between gas gun experiments and NIF experiments. The states are compared with the Hugoniots of quartz and fused silica formore » inferences as to EOS. They are generally consistent with Sesame 7360 predictions. Sound speed constraints from these data are discussed. The new Hugoniot data cross over the melting curve of stishovite; together with the partial-release data and predictions from density-functional theory modeling, they provide insights into the properties of solid and liquid under extreme conditions. These data are fundamentally important for understanding the interior of silicate-based super-Earths.« less

Partially Ionized Beam Deposition of Silicon-Dioxide and Aluminum Thin Films - Defects Generation.

NASA Astrophysics Data System (ADS)

Wong, Justin Wai-Chow

1987-09-01

Detect formation in SiO_2 and Al thin films and interfaces were studied using a partially ionized beam (PIB) deposition technique. The evaporated species (the deposition material) were partially ionized to give an ion/atom ratio of <=q0.1% and the substrate was biased at 0-5kV during the deposition. The results suggest that due to the ion bombardment, stoichiometric SiO_2 films can be deposited at a low substrate temperature (~300 ^circC) and low oxygen pressure (<=q10^{-4} Torr). Such deposition cannot be achieved using conventional evaporation-deposition techniques. However, traps and mobile ions were observed in the oxide and local melt-down was observed when a sufficiently high electric field was applied to the film. For the PIB Al deposition on the Si substrate, stable Al/Si Schottky contact was formed when the substrate bias was <=q1kV. For a substrate bias of 2.5kV, the capacitance of the Al/Si interface increased dramatically. A model of self-ion implantation with a p-n junction created by the Al^+ ion implantation was proposed and tested to explain the increase of the interface capacitance. Several deep level states at the Al/Si interface were observed using Deep Level Transient Spectroscopy (DLTS) technique when the film was deposited at a bias of 3kV. The PIB Al films deposited on the Si substrate showed unusually strong electromigration resistance under high current density operation. This phenomenon was explained by the highly oriented microstructure of the Al films created by the self-ion bombardment during deposition. These findings show that PIB has potential applications in a number of areas, including low temperature thin film deposition, and epitaxial growth of thin films in the microelectronics thin film industry.

Adolescent and young adult female determinants of visceral adipose tissue at ages 26-28 years.

PubMed

Glueck, Charles J; Wang, Ping; Woo, Jessica G; Morrison, John A; Khoury, Philip R; Daniels, Stephen R

2015-04-01

To assess adolescent and young adult determinants of visceral adipose tissue (VAT) at ages 26-28 years. Prospective study (ages 9-28 years) of cardiometabolic measures, menarche age, menses irregularities, metabolic syndrome, impaired fasting glucose-type 2 diabetes mellitus, and VAT in 400 girls (248 black, 152 white). Adolescent (age 14-19) independent variables for greater VAT at ages 26-28 included larger mean waist circumference (partial R(2) = 30.8%), earlier age at menarche (0.9%), and white race (1.8%). Young adult (ages 20-28 years) independent variables for greater VAT included larger mean waist circumference (partial R(2) = 61.7%), greater triglyceride levels (3.3%), lower high-density lipoprotein cholesterol (1.0%), and greater insulin resistance (homeostasis model assessment-estimated insulin resistance; 0.4%). Independent variables for greater VAT when both adolescent and young adult variables were used included waist (tertile rank change from adolescence to young adulthood, partial R(2) = 58.3%), greater young adult triglyceride levels (4.4%), white race (1.8%), greater young adult homeostasis model assessment-estimated insulin resistance (age 20-28, 2.4%), and earlier menarche age (0.7%). Menses irregularities were not independently associated with young adult VAT. Adolescent girls with early menarche and larger waist circumference should be targets for primary prevention of accretion of VAT. In young adulthood, VAT is associated with dysregulated cardiometabolic profiles, which is greater for those with waist circumference increases from adolescence to adulthood. Waist circumference during young adulthood, and to a lesser degree during adolescence, is an inexpensive surrogate for VAT at ages 26-28 years. Copyright © 2015 Elsevier Inc. All rights reserved.

Background mortality rates for recovering populations of Acropora cytherea in the Chagos Archipelago, central Indian Ocean.

PubMed

Pratchett, M S; Pisapia, C; Sheppard, C R C

2013-05-01

This study quantified background rates of mortality for Acropora cytherea in the Chagos Archipelago. Despite low levels of anthropogenic disturbance, 27.5% (149/541) of A. cytherea colonies exhibited some level of partial mortality, and 9.0% (49/541) of colonies had recent injuries. A total of 15.3% of the overall surface area of physically intact A. cytherea colonies was dead. Observed mortality was partly attributable to overtopping and/or self-shading among colonies. There were also low-densities of Acanthaster planci apparent at some study sites. However, most of the recent mortality recorded was associated with isolated infestations of the coral crab, Cymo melanodactylus. A. cytherea is a relatively fast growing coral and these levels of mortality may be biologically unimportant. However, few studies have measured background rates of coral mortality, especially in the absence of direct human disturbances. These data are important for assessing the impacts of increasing disturbances, especially in projecting likely recovery. Copyright © 2013. Published by Elsevier Ltd.

Propagation of partially coherent Lorentz and Lorentz-Gauss beams through a paraxial ABCD optical system in a turbulent atmosphere

NASA Astrophysics Data System (ADS)

Zhao, Chengliang; Cai, Yangjian

2011-05-01

Based on the generalized Huygens-Fresnel integral, propagation of partially coherent Lorentz and Lorentz-Gauss beams through a paraxial ABCD optical system in a turbulent atmosphere was investigated. Analytical propagation formulae were derived for the cross-spectral densities of partially coherent Lorentz and Lorentz-Gauss beams. As an application example, the focusing properties of partially coherent Gaussian, Lorentz and Lorentz-Gauss beams in a turbulent atmosphere and in free space were studied numerically and comparatively. It is found that the focusing properties of such beams are closely related to the initial coherence length and the structure constant of turbulence. By choosing a suitable initial coherence length, a partially coherent Lorentz beam can be focused more tightly than a Gaussian or Lorentz-Gauss beam in free space or in a turbulent atmosphere with small structure constant at the geometrical focal plane.

From stochastic processes to numerical methods: A new scheme for solving reaction subdiffusion fractional partial differential equations

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

Angstmann, C.N.; Donnelly, I.C.; Henry, B.I., E-mail: B.Henry@unsw.edu.au

We have introduced a new explicit numerical method, based on a discrete stochastic process, for solving a class of fractional partial differential equations that model reaction subdiffusion. The scheme is derived from the master equations for the evolution of the probability density of a sum of discrete time random walks. We show that the diffusion limit of the master equations recovers the fractional partial differential equation of interest. This limiting procedure guarantees the consistency of the numerical scheme. The positivity of the solution and stability results are simply obtained, provided that the underlying process is well posed. We also showmore » that the method can be applied to standard reaction–diffusion equations. This work highlights the broader applicability of using discrete stochastic processes to provide numerical schemes for partial differential equations, including fractional partial differential equations.« less

Interrelationship between lignin-rich dichloromethane extracts of hot water-treated wood fibers and high-density polyethylene (HDPE) in wood plastic composite (WPC) production

Treesearch

Manuel R. Pelaez-Samaniego; Vikram Yadama; Manuel Garcia-Perez; Eini Lowell; Rui Zhu; Karl Englund

2016-01-01

Hot water extraction (HWE) partially removes hemicelluloses from wood while leaving the majority of the lignin and cellulose; however, the lignin partially migrates to the inner surfaces of the cell wall where it can be deposited as a layer that is sometimes visible as droplets. This lignin-rich material was isolated via Soxhlet extraction with dichloromethane to...

The role of rare-earth dopants in tailoring the magnetism and magnetic anisotropy in Fe4N

NASA Astrophysics Data System (ADS)

Li, Zirun; Mi, Wenbo; Bai, Haili

2018-05-01

The magnetism and magnetic anisotropy of the rare-earth (RE) atom-substituted Fe4N are investigated by first-principles calculations. It is found that the substitution of one RE atom results in an antiferromagnetic coupling with the Fe atoms. The 4f-3d exchange interaction has an important influence on the density of states of Fe near the Fermi level. PrFe3N and NdFe3N with a tetragonal structure exhibit giant magnetic anisotropy energy larger than 5 meV/atom. The magnetic anisotropy depends on the distribution of partial states of d or f orbital near the Fermi level. As Eu substitutes Fe in Fe4N, the magnetic moment of Eu3FeN even exceeds 23 μB. Our theoretical predictions point out the possibilities of tuning the magnetism and magnetic anisotropy of Fe4N upon RE doping.

Theory of space charge limited currents in films and nanowires with dopants

NASA Astrophysics Data System (ADS)

Zhang, Xiaoguang; Pantelides, Sokrates

2015-03-01

We show that proper description of the space charge limited currents (SCLC) in a homogeneous bulk material must account fully for the effect of the dopants and the interplay between dopants and traps. The sharp rise in the current at the trap-filled-limit (TFL) is partially mitigated by the dopant energy levels and the Frenkel effect, namely the lowering of the ionization energy by the electric field, which is screened by the free carriers. In nanowires, lack of effective screening causes the trap occupation at small biases to reach a high level comparable to the TFL in bulk. This explains the high current density in SCLCs observed in nanowires. This work is supported by the LDRD program at ORNL. Portion of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

Three-Dimensional Nanometer Features of Direct Current Electrical Trees in Low-Density Polyethylene.

PubMed

Pallon, Love K H; Nilsson, Fritjof; Yu, Shun; Liu, Dongming; Diaz, Ana; Holler, Mirko; Chen, Xiangrong R; Gubanski, Stanislaw; Hedenqvist, Mikael S; Olsson, Richard T; Gedde, Ulf W

2017-03-08

Electrical trees are one reason for the breakdown of insulating materials in electrical power systems. An understanding of the growth of electrical trees plays a crucial role in the development of reliable high voltage direct current (HVDC) power grid systems with transmission voltages up to 1 MV. A section that contained an electrical tree in low-density polyethylene (LDPE) has been visualized in three dimensions (3D) with a resolution of 92 nm by X-ray ptychographic tomography. The 3D imaging revealed prechannel-formations with a lower density with the width of a couple of hundred nanometers formed around the main branch of the electrical tree. The prechannel structures were partially connected with the main tree via paths through material with a lower density, proving that the tree had grown in a step-by-step manner via the prestep structures formed in front of the main channels. All the prechannel structures had a size well below the limit of the Paschen law and were thus not formed by partial discharges. Instead, it is suggested that the prechannel structures were formed by electro-mechanical stress and impact ionization, where the former was confirmed by simulations to be a potential explanation with electro-mechanical stress tensors being almost of the same order of magnitude as the short-term modulus of low-density polyethylene.

Combined hydraulic and regenerative braking system

DOEpatents

Venkataperumal, R.R.; Mericle, G.E.

1979-08-09

A combined hydraulic and regenerative braking system and method for an electric vehicle is disclosed. The braking system is responsive to the applied hydraulic pressure in a brake line to control the braking of the vehicle to be completely hydraulic up to a first level of brake line pressure, to be partially hydraulic at a constant braking force and partially regenerative at a linearly increasing braking force from the first level of applied brake line pressure to a higher second level of brake line pressure, to be partially hydraulic at a linearly increasing braking force and partially regenerative at a linearly decreasing braking force from the second level of applied line pressure to a third and higher level of applied line pressure, and to be completely hydraulic at a linearly increasing braking force from the third level to all higher applied levels of line pressure.

Combined hydraulic and regenerative braking system

DOEpatents

Venkataperumal, Rama R.; Mericle, Gerald E.

1981-06-02

A combined hydraulic and regenerative braking system and method for an electric vehicle, with the braking system being responsive to the applied hydraulic pressure in a brake line to control the braking of the vehicle to be completely hydraulic up to a first level of brake line pressure, to be partially hydraulic at a constant braking force and partially regenerative at a linearly increasing braking force from the first level of applied brake line pressure to a higher second level of brake line pressure, to be partially hydraulic at a linearly increasing braking force and partially regenerative at a linearly decreasing braking force from the second level of applied line pressure to a third and higher level of applied line pressure, and to be completely hydraulic at a linearly increasing braking force from the third level to all higher applied levels of line pressure.

Vibration analysis of partially cracked plate submerged in fluid

NASA Astrophysics Data System (ADS)

Soni, Shashank; Jain, N. K.; Joshi, P. V.

2018-01-01

The present work proposes an analytical model for vibration analysis of partially cracked rectangular plates coupled with fluid medium. The governing equation of motion for the isotropic plate based on the classical plate theory is modified to accommodate a part through continuous line crack according to simplified line spring model. The influence of surrounding fluid medium is incorporated in the governing equation in the form of inertia effects based on velocity potential function and Bernoulli's equations. Both partially and totally submerged plate configurations are considered. The governing equation also considers the in-plane stretching due to lateral deflection in the form of in-plane forces which introduces geometric non-linearity into the system. The fundamental frequencies are evaluated by expressing the lateral deflection in terms of modal functions. The assessment of the present results is carried out for intact submerged plate as to the best of the author's knowledge the literature lacks in analytical results for submerged cracked plates. New results for fundamental frequencies are presented as affected by crack length, fluid level, fluid density and immersed depth of plate. By employing the method of multiple scales, the frequency response and peak amplitude of the cracked structure is analyzed. The non-linear frequency response curves show the phenomenon of bending hardening or softening and the effect of fluid dynamic pressure on the response of the cracked plate.

An equation of state for partially ionized plasmas: The Coulomb contribution to the free energy

NASA Astrophysics Data System (ADS)

Kilcrease, D. P.; Colgan, J.; Hakel, P.; Fontes, C. J.; Sherrill, M. E.

2015-09-01

We have previously developed an equation of state (EOS) model called ChemEOS (Hakel and Kilcrease, Atomic Processes in Plasmas, Eds., J. Cohen et al., AIP, 2004) for a plasma of interacting ions, atoms and electrons. It is based on a chemical picture of the plasma and is derived from an expression for the Helmholtz free energy of the interacting species. All other equilibrium thermodynamic quantities are then obtained by minimizing this free energy subject to constraints, thus leading to a thermodynamically consistent EOS. The contribution to this free energy from the Coulomb interactions among the particles is treated using the method of Chabrier and Potekhin (Phys. Rev. E 58, 4941 (1998)) which we have adapted for partially ionized plasmas. This treatment is further examined and is found to give rise to unphysical behavior for various elements at certain values of the density and temperature where the Coulomb coupling begins to become significant and the atoms are partially ionized. We examine the source of this unphysical behavior and suggest corrections that produce acceptable results. The sensitivity of the thermodynamic properties and frequency-dependent opacity of iron is examined with and without these corrections. The corrected EOS is used to determine the fractional ion populations and level populations for a new generation of OPLIB low-Z opacity tables currently being prepared at Los Alamos National Laboratory with the ATOMIC code.

Partial Molar Volumes of Aqua Ions from First Principles.

PubMed

Wiktor, Julia; Bruneval, Fabien; Pasquarello, Alfredo

2017-08-08

Partial molar volumes of ions in water solution are calculated through pressures obtained from ab initio molecular dynamics simulations. The correct definition of pressure in charged systems subject to periodic boundary conditions requires access to the variation of the electrostatic potential upon a change of volume. We develop a scheme for calculating such a variation in liquid systems by setting up an interface between regions of different density. This also allows us to determine the absolute deformation potentials for the band edges of liquid water. With the properly defined pressures, we obtain partial molar volumes of a series of aqua ions in very good agreement with experimental values.

Densification and Electrical Properties of Zinc Oxide Varistors Microwave-Sintered Under Different Oxygen Partial Pressures

NASA Astrophysics Data System (ADS)

Lin, Cong; Wang, Bo; Xu, Zheng; Peng, Hu

2012-11-01

ZnO varistors were prepared by microwave sintering under different oxygen partial pressures. The temperature profile and the densification behavior in different atmospheres were investigated. It was found that the density of ZnO varistors during sintering was the key factor affecting the absorption of microwave energy. The electrical properties, including the nonlinear properties and capacitance-voltage ( C- V) characteristics, were also carefully studied. The results showed that the oxygen partial pressure has significant effects on the electrical properties of ZnO varistors by changing the concentration of defects through a series of reactions involving oxygen during sintering.

Cosine-Gaussian Schell-model sources.

PubMed

Mei, Zhangrong; Korotkova, Olga

2013-07-15

We introduce a new class of partially coherent sources of Schell type with cosine-Gaussian spectral degree of coherence and confirm that such sources are physically genuine. Further, we derive the expression for the cross-spectral density function of a beam generated by the novel source propagating in free space and analyze the evolution of the spectral density and the spectral degree of coherence. It is shown that at sufficiently large distances from the source the degree of coherence of the propagating beam assumes Gaussian shape while the spectral density takes on the dark-hollow profile.

Cell density signal protein suitable for treatment of connective tissue injuries and defects

DOEpatents

Schwarz, Richard I.

2002-08-13

Identification, isolation and partial sequencing of a cell density protein produced by fibroblastic cells. The cell density signal protein comprising a 14 amino acid peptide or a fragment, variant, mutant or analog thereof, the deduced cDNA sequence from the 14 amino acid peptide, a recombinant protein, protein and peptide-specific antibodies, and the use of the peptide and peptide-specific antibodies as therapeutic agents for regulation of cell differentiation and proliferation. A method for treatment and repair of connective tissue and tendon injuries, collagen deficiency, and connective tissue defects.

Meta-analysis of genome-wide association studies of HDL cholesterol response to statins

PubMed Central

Postmus, Iris; Warren, Helen R; Trompet, Stella; Arsenault, Benoit J; Avery, Christy L; Bis, Joshua C; Chasman, Daniel I; de Keyser, Catherine E; Deshmukh, Harshal A; Evans, Daniel S; Feng, QiPing; Li, Xiaohui; Smit, Roelof AJ; Smith, Albert V; Sun, Fangui; Taylor, Kent D; Arnold, Alice M; Barnes, Michael R; Barratt, Bryan J; Betteridge, John; Boekholdt, S Matthijs; Boerwinkle, Eric; Buckley, Brendan M; Chen, Y-D Ida; de Craen, Anton JM; Cummings, Steven R; Denny, Joshua C; Dubé, Marie Pierre; Durrington, Paul N; Eiriksdottir, Gudny; Ford, Ian; Guo, Xiuqing; Harris, Tamara B; Heckbert, Susan R; Hofman, Albert; Hovingh, G Kees; Kastelein, John JP; Launer, Leonore J; Liu, Ching-Ti; Liu, Yongmei; Lumley, Thomas; McKeigue, Paul M; Munroe, Patricia B; Neil, Andrew; Nickerson, Deborah A; Nyberg, Fredrik; O’Brien, Eoin; O’Donnell, Christopher J; Post, Wendy; Poulter, Neil; Vasan, Ramachandran S; Rice, Kenneth; Rich, Stephen S; Rivadeneira, Fernando; Sattar, Naveed; Sever, Peter; Shaw-Hawkins, Sue; Shields, Denis C; Slagboom, P Eline; Smith, Nicholas L; Smith, Joshua D; Sotoodehnia, Nona; Stanton, Alice; Stott, David J; Stricker, Bruno H; Stürmer, Til; Uitterlinden, André G; Wei, Wei-Qi; Westendorp, Rudi GJ; Whitsel, Eric A; Wiggins, Kerri L; Wilke, Russell A; Ballantyne, Christie M; Colhoun, Helen M; Cupples, L Adrienne; Franco, Oscar H; Gudnason, Vilmundur; Hitman, Graham; Palmer, Colin NA; Psaty, Bruce M; Ridker, Paul M; Stafford, Jeanette M; Stein, Charles M; Tardif, Jean-Claude; Caulfield, Mark J; Jukema, J Wouter; Rotter, Jerome I; Krauss, Ronald M

2017-01-01

Background In addition to lowering low density lipoprotein-cholesterol (LDL-C), statin therapy also raises high density lipoprotein-cholesterol (HDL-C) levels. Inter-individual variation in HDL-C response to statins may be partially explained by genetic variation. Methods and Results We performed a meta-analysis of genome-wide association studies (GWAS) to identify variants with an effect on statin-induced HDL-C changes. The 123 most promising signals with P<1×10−4 from the 16,769 statin-treated participants in the first analysis stage were followed up in an independent group of 10,951 statin-treated individuals, providing a total sample size of 27,720 individuals. The only associations of genome-wide significance (P<5×10−8) were between minor alleles at the CETP locus and greater HDL-C response to statin treatment. Conclusion Based on results from this study that included a relatively large sample size, we suggest that CETP may be the only detectable locus with common genetic variants that influence HDL-C response to statins substantially in individuals of European descent. Although CETP is known to be associated with HDL-C, we provide evidence that this pharmacogenetic effect is independent of its association with baseline HDL-C levels. PMID:27587472

Juvenile anadromous salmonid production in upper Columbia River side channels with different levels of hydrological connection

USGS Publications Warehouse

Martens, Kyle D.; Connolly, Patrick J.

2014-01-01

We examined the contribution of three types of side channels based on their hydrologic connectivity (seasonally disconnected, partially connected, and connected) to production of juvenile anadromous salmonids. Juvenile steelhead Oncorhynchus mykiss and Chinook Salmon O. tshawytscha were found in all three of these side channel types and in each year of the study. Upon connection with the main stem at high flows, the seasonally disconnected side channels experienced an emptying out of the previous year's fish while filling with young-of-year fish during the 2- to 4-month period of hydrologic connection. There were no differences between the densities of juvenile steelhead and Chinook Salmon and the rate of smolts produced among the three types of side channels. Recently reintroduced Coho Salmon O. kisutch had sporadic presence and abundance in partially and connected side channels, but the smolt production rate was over two times that of steelhead and Chinook Salmon in seasonally disconnected side channels. Within seasonally disconnected side channels, young-of-year salmonids in deep pools (≥100 cm) had greater survival than those in shallow pools (<100 cm). Densities of juvenile steelhead in all side channel types were similar to those in tributaries and were higher than in main-stem lateral margins. Juvenile Chinook Salmon densities were higher in side channels than in both tributary and main-stem lateral margins. Our results suggest that improving quality of pool habitat within seasonally disconnected side channels can result in improved survival for juvenile anadromous salmonids during the period of disconnection. Habitat improvement in these seasonally disconnected side channels should be recognized as a worthy restoration strategy, especially when full connectivity of side channels may not be a feasible target (e.g., through lack of water availability) or when full connectivity may present too high a risk (e.g., flooding, stream capture, bank destabilization).

Spatial capture–recapture with partial identity: An application to camera traps

USGS Publications Warehouse

Augustine, Ben C.; Royle, J. Andrew; Kelly, Marcella J.; Satter, Christopher B.; Alonso, Robert S.; Boydston, Erin E.; Crooks, Kevin R.

2018-01-01

Camera trapping surveys frequently capture individuals whose identity is only known from a single flank. The most widely used methods for incorporating these partial identity individuals into density analyses discard some of the partial identity capture histories, reducing precision, and, while not previously recognized, introducing bias. Here, we present the spatial partial identity model (SPIM), which uses the spatial location where partial identity samples are captured to probabilistically resolve their complete identities, allowing all partial identity samples to be used in the analysis. We show that the SPIM outperforms other analytical alternatives. We then apply the SPIM to an ocelot data set collected on a trapping array with double-camera stations and a bobcat data set collected on a trapping array with single-camera stations. The SPIM improves inference in both cases and, in the ocelot example, individual sex is determined from photographs used to further resolve partial identities—one of which is resolved to near certainty. The SPIM opens the door for the investigation of trapping designs that deviate from the standard two camera design, the combination of other data types between which identities cannot be deterministically linked, and can be extended to the problem of partial genotypes.

Neuronal Activity in the Subthalamic Cerebrovasodilator Area under Partial-Gravity Conditions in Rats

PubMed Central

Zeredo, Jorge L.; Toda, Kazuo; Kumei, Yasuhiro

2014-01-01

The reduced-gravity environment in space is known to cause an upward shift in body fluids and thus require cardiovascular adaptations in astronauts. In this study, we recorded in rats the neuronal activity in the subthalamic cerebrovasodilator area (SVA), a key area that controls cerebral blood flow (CBF), in response to partial gravity. “Partial gravity” is the term that defines the reduced-gravity levels between 1 g (the unit gravity acceleration on Earth) and 0 g (complete weightlessness in space). Neuronal activity was recorded telemetrically through chronically implanted microelectrodes in freely moving rats. Graded levels of partial gravity from 0.4 g to 0.01 g were generated by customized parabolic-flight maneuvers. Electrophysiological signals in each partial-gravity phase were compared to those of the preceding 1 g level-flight. As a result, SVA neuronal activity was significantly inhibited by the partial-gravity levels of 0.15 g and lower, but not by 0.2 g and higher. Gravity levels between 0.2–0.15 g could represent a critical threshold for the inhibition of neurons in the rat SVA. The lunar gravity (0.16 g) might thus trigger neurogenic mechanisms of CBF control. This is the first study to examine brain electrophysiology with partial gravity as an experimental parameter. PMID:25370031

Detection of deep-level defects and reduced carrier concentration in Mg-ion-implanted GaN before high-temperature annealing

NASA Astrophysics Data System (ADS)

Akazawa, Masamichi; Yokota, Naoshige; Uetake, Kei

2018-02-01

We report experimental results for the detection of deep-level defects in GaN after Mg ion implantation before high-temperature annealing. The n-type GaN samples were grown on GaN free-standing substrates by metalorganic vapor phase epitaxy. Mg ions were implanted at 50 keV with a small dosage of 1.5×1011 cm-2, which did not change the conduction type of the n-GaN. By depositing Al2O3 and a Ni/Au electrode onto the implanted n-GaN, metal-oxide-semiconductor (MOS) diodes were fabricated and tested. The measured capacitance-voltage (C-V) characteristics showed a particular behavior with a plateau region and a region with an anomalously steep slope. Fitting to the experimental C-V curves by simulation showed the existence of deep-level defects and a reduction of the carrier concentration near the GaN surface. By annealing at 800oC, the density of the deep-level defects was reduced and the carrier concentration partially recovered.

Metabolomics reveals distinct, antibody-independent, molecular signatures of MS, AQP4-antibody and MOG-antibody disease.

PubMed

Jurynczyk, Maciej; Probert, Fay; Yeo, Tianrong; Tackley, George; Claridge, Tim D W; Cavey, Ana; Woodhall, Mark R; Arora, Siddharth; Winkler, Torsten; Schiffer, Eric; Vincent, Angela; DeLuca, Gabriele; Sibson, Nicola R; Isabel Leite, M; Waters, Patrick; Anthony, Daniel C; Palace, Jacqueline

2017-12-06

The overlapping clinical features of relapsing remitting multiple sclerosis (RRMS), aquaporin-4 (AQP4)-antibody (Ab) neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein (MOG)-Ab disease mean that detection of disease specific serum antibodies is the gold standard in diagnostics. However, antibody levels are not prognostic and may become undetectable after treatment or during remission. Therefore, there is still a need to discover antibody-independent biomarkers. We sought to discover whether plasma metabolic profiling could provide biomarkers of these three diseases and explore if the metabolic differences are independent of antibody titre. Plasma samples from 108 patients (34 RRMS, 54 AQP4-Ab NMOSD, and 20 MOG-Ab disease) were analysed by nuclear magnetic resonance spectroscopy followed by lipoprotein profiling. Orthogonal partial-least squares discriminatory analysis (OPLS-DA) was used to identify significant differences in the plasma metabolite concentrations and produce models (mathematical algorithms) capable of identifying these diseases. In all instances, the models were highly discriminatory, with a distinct metabolite pattern identified for each disease. In addition, OPLS-DA identified AQP4-Ab NMOSD patient samples with low/undetectable antibody levels with an accuracy of 92%. The AQP4-Ab NMOSD metabolic profile was characterised by decreased levels of scyllo-inositol and small high density lipoprotein particles along with an increase in large low density lipoprotein particles relative to both RRMS and MOG-Ab disease. RRMS plasma exhibited increased histidine and glucose, along with decreased lactate, alanine, and large high density lipoproteins while MOG-Ab disease plasma was defined by increases in formate and leucine coupled with decreased myo-inositol. Despite overlap in clinical measures in these three diseases, the distinct plasma metabolic patterns support their distinct serological profiles and confirm that these conditions are indeed different at a molecular level. The metabolites identified provide a molecular signature of each condition which is independent of antibody titre and EDSS, with potential use for disease monitoring and diagnosis.

Correlation of Hall and Shubnikov-de Haas Oscillations and Impurity States in Sn- and I- Doped Single Crystals p-Bi 2 Te 3

NASA Astrophysics Data System (ADS)

Tahar, M. Z.; Popov, D. I.; Nemov, S. A.

2018-03-01

Oscillations of the Hall coefficient and Shubnikov-de Haas (SdH) were observed in p-Bi2Te3 crystals doped with Sn (acceptor) and with I (donor) in magnetic fields up to 9 T parallel to the C3 trigonal axis at low temperatures (2 K < T < 20K), which is an evidence of the spatial homogeneity of carriers in complex solid solutions. This supports the existence of a narrow band of Sn states (partially filled) against the background of the valence band acting as a reservoir with high density of states partially filled with electrons. Previously, in these systems in which the Fermi level was in the light-hole valence band, both large Hall and SdH oscillations were observed, with ∼π phase shift between them, whereas when the Fermi level was in the heavy-hole valence band (larger acceptor content), no quantum oscillations were observed. It was concluded that the observed low amplitude quantum oscillations may be attributed to the shifting of the reservoir from the light-hole band to the heavy-hole, and the observed phase shift in the range 0 - π/2 between Hall and SdH oscillations may be attributed to filling factor of the reservoir with electrons, which varies with I content. Experimental results along with theoretical explanation of these correlations are presented.

Dynamics of cavitation clouds within a high-intensity focused ultrasonic beam

NASA Astrophysics Data System (ADS)

Lu, Yuan; Katz, Joseph; Prosperetti, Andrea

2013-07-01

In this experimental study, we generate a 500 kHz high-intensity focused ultrasonic beam, with pressure amplitude in the focal zone of up to 1.9 MPa, in initially quiescent water. The resulting pressure field and behavior of the cavitation bubbles are measured using high-speed digital in-line holography. Variations in the water density and refractive index are used for determining the spatial distribution of the acoustic pressure nonintrusively. Several cavitation phenomena occur within the acoustic partially standing wave caused by the reflection of sound from the walls of the test chamber. At all sound levels, bubbly layers form in the periphery of the focal zone in the pressure nodes of the partial standing wave. At high sound levels, clouds of vapor microbubbles are generated and migrate in the direction of the acoustic beam. Both the cloud size and velocity vary periodically, with the diameter peaking at the pressure nodes and velocity at the antinodes. A simple model involving linearized bubble dynamics, Bjerknes forces, sound attenuation by the cloud, added mass, and drag is used to predict the periodic velocity of the bubble cloud, as well as qualitatively explain the causes for the variations in the cloud size. The analysis shows that the primary Bjerknes force and drag dominate the cloud motion, and suggests that the secondary Bjerknes force causes the oscillations in the cloud size.

Sizes of nanobubbles from nucleation rate measurements

NASA Astrophysics Data System (ADS)

Wilemski, G.

2003-03-01

In homogeneous bubble nucleation, the critical nucleus typically has nanometer dimensions. The volume V of a critical bubble can be determined from the simple equation (partial W/partial p)_T=V, where W is the reversible work of nucleus formation and p is the ambient pressure of the liquid phase in which bubble formation is occurring. The relation, W/kT=-ln J+ln A, where J is the steady state nucleation rate and A is the weakly pressure-dependent kinetic prefactor, allows V to be determined from rate measurements. The original derivation of this equation for V from the nucleation theorem was limited to one-component, ideal gas bubbles with a gas density much smaller than that of the ambient liquid. [D. Kashchiev, Nucleation: basic theory with applications (Butterworth-Heinemann, Oxford, 2000) p. 226.] The result is actually much more general, and it will be shown that it applies to multi-component, nonideal gas bubbles, provided the same density inequality holds. When the bubble phase and liquid densities are comparable, a more complicated, but also general and rigorous result is found.

Partial detachment of high power discharges in ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Kallenbach, A.; Bernert, M.; Beurskens, M.; Casali, L.; Dunne, M.; Eich, T.; Giannone, L.; Herrmann, A.; Maraschek, M.; Potzel, S.; Reimold, F.; Rohde, V.; Schweinzer, J.; Viezzer, E.; Wischmeier, M.; the ASDEX Upgrade Team

2015-05-01

Detachment of high power discharges is obtained in ASDEX Upgrade by simultaneous feedback control of core radiation and divertor radiation or thermoelectric currents by the injection of radiating impurities. So far 2/3 of the ITER normalized heat flux Psep/R = 15 MW m-1 has been obtained in ASDEX Upgrade under partially detached conditions with a peak target heat flux well below 10 MW m-2. When the detachment is further pronounced towards lower peak heat flux at the target, substantial changes in edge localized mode (ELM) behaviour, density and radiation distribution occur. The time-averaged peak heat flux at both divertor targets can be reduced below 2 MW m-2, which offers an attractive DEMO divertor scenario with potential for simpler and cheaper technical solutions. Generally, pronounced detachment leads to a pedestal and core density rise by about 20-40%, moderate (<20%) confinement degradation and a reduction of ELM size. For AUG conditions, some operational challenges occur, like the density cut-off limit for X-2 electron cyclotron resonance heating, which is used for central tungsten control.

Realistic respiratory motion margins for external beam partial breast irradiation

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

Conroy, Leigh; Quirk, Sarah; Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4

Purpose: Respiratory margins for partial breast irradiation (PBI) have been largely based on geometric observations, which may overestimate the margin required for dosimetric coverage. In this study, dosimetric population-based respiratory margins and margin formulas for external beam partial breast irradiation are determined. Methods: Volunteer respiratory data and anterior–posterior (AP) dose profiles from clinical treatment plans of 28 3D conformal radiotherapy (3DCRT) PBI patient plans were used to determine population-based respiratory margins. The peak-to-peak amplitudes (A) of realistic respiratory motion data from healthy volunteers were scaled from A = 1 to 10 mm to create respiratory motion probability density functions. Dosemore » profiles were convolved with the respiratory probability density functions to produce blurred dose profiles accounting for respiratory motion. The required margins were found by measuring the distance between the simulated treatment and original dose profiles at the 95% isodose level. Results: The symmetric dosimetric respiratory margins to cover 90%, 95%, and 100% of the simulated treatment population were 1.5, 2, and 4 mm, respectively. With patient set up at end exhale, the required margins were larger in the anterior direction than the posterior. For respiratory amplitudes less than 5 mm, the population-based margins can be expressed as a fraction of the extent of respiratory motion. The derived formulas in the anterior/posterior directions for 90%, 95%, and 100% simulated population coverage were 0.45A/0.25A, 0.50A/0.30A, and 0.70A/0.40A. The differences in formulas for different population coverage criteria demonstrate that respiratory trace shape and baseline drift characteristics affect individual respiratory margins even for the same average peak-to-peak amplitude. Conclusions: A methodology for determining population-based respiratory margins using real respiratory motion patterns and dose profiles in the AP direction was described. It was found that the currently used respiratory margin of 5 mm in partial breast irradiation may be overly conservative for many 3DCRT PBI patients. Amplitude alone was found to be insufficient to determine patient-specific margins: individual respiratory trace shape and baseline drift both contributed to the dosimetric target coverage. With respiratory coaching, individualized respiratory margins smaller than the full extent of motion could reduce planning target volumes while ensuring adequate coverage under respiratory motion.« less

Quantification of dislocation nucleation stress in TiN through high-resolution in situ indentation experiments and first principles calculations

DOE PAGES

Li, N.; Yadav, S. K.; Liu, X. -Y.; ...

2015-11-05

Using the in situ indentation of TiN in a high-resolution transmission electron microscope, the nucleation of full as well as partial dislocations has been observed from {001} and {111} surfaces, respectively. The critical elastic strains associated with the nucleation of the dislocations were analyzed from the recorded atomic displacements, and the nucleation stresses corresponding to the measured critical strains were computed using density functional theory. The resolved shear stress was estimated to be 13.8 GPa for the partial dislocation 1/6 <110> {111} and 6.7 GPa for the full dislocation ½ <110> {110}. Moreover, such an approach of quantifying nucleation stressesmore » for defects via in situ high-resolution experiment coupled with density functional theory calculation may be applied to other unit processes.« less

Optimising yield and resource utilisation of summer maize under the conditions of increasing density and reducing nitrogen fertilization.

PubMed

Wei, Shanshan; Wang, Xiangyu; Zhu, Qicen; Jiang, Dong; Dong, Shuting

2017-10-05

The inefficient use of resources always poses risks of maize (Zea mays L.) yield reduction in China. We performed this research to monitor the effects of increasing plant density and reducing nitrogen (N) rate on radiation-use efficiency (RUE), N efficiency traits, grain yield (GY) and their inter-relationships. Besides, whether GY and resource-use efficiency can both be maximized was examined. Hence, a 2-year field experiment was conducted using a widely grown variety "Denghai 618" in Shandong, China. Treatments contained two different plant densities [67,500 (D 1 ) and 97,500 (D 2 ) plant ha -1 ] and three N levels [0 (N -2 ), 180 (N -1 ), 360 (N ck ) kg ha -1 ], set D 1 N ck as control. Significant increases in grain yield, biomass, RUE, above-ground N uptake (AGN) and N efficiency were observed when density increased from D 1 to D 2 . Declining N application was accompanied by reductions in yield, RUE and AGN especially under high density, yet an obvious improvement in N recovery efficiency (NRE), agronomic N efficiency and N partial factor productivity. The increased GY was positive related with population biomass (r = 0.895**), RUE (r = 0.769**) and AGN (r = 0.923**), whereas it has no significant correlation with N efficiency. In this study, D 2 N ck obtained 18.8, 17.9, 24.8 and 29.7% higher grain yield, RUE, AGN and NRE respectively, compared to control, optimizing both yield and the efficiencies of radiation and N use. Furthermore, higher yield and RUE with more desirable N efficiency may be possible via optimizing density and N rate combination.

Optimising yield and resource utilisation of summer maize under the conditions of increasing density and reducing nitrogen fertilization

NASA Astrophysics Data System (ADS)

Wei, Shanshan; Wang, Xiangyu; Zhu, Qicen; Jiang, Dong; Dong, Shuting

2017-12-01

The inefficient use of resources always poses risks of maize ( Zea mays L.) yield reduction in China. We performed this research to monitor the effects of increasing plant density and reducing nitrogen (N) rate on radiation-use efficiency (RUE), N efficiency traits, grain yield (GY) and their inter-relationships. Besides, whether GY and resource-use efficiency can both be maximized was examined. Hence, a 2-year field experiment was conducted using a widely grown variety "Denghai 618" in Shandong, China. Treatments contained two different plant densities [67,500 (D1) and 97,500 (D2) plant ha-1] and three N levels [0 (N-2), 180 (N-1), 360 (Nck) kg ha-1], set D1Nck as control. Significant increases in grain yield, biomass, RUE, above-ground N uptake (AGN) and N efficiency were observed when density increased from D1 to D2. Declining N application was accompanied by reductions in yield, RUE and AGN especially under high density, yet an obvious improvement in N recovery efficiency (NRE), agronomic N efficiency and N partial factor productivity. The increased GY was positive related with population biomass ( r = 0.895**), RUE ( r = 0.769**) and AGN ( r = 0.923**), whereas it has no significant correlation with N efficiency. In this study, D2Nck obtained 18.8, 17.9, 24.8 and 29.7% higher grain yield, RUE, AGN and NRE respectively, compared to control, optimizing both yield and the efficiencies of radiation and N use. Furthermore, higher yield and RUE with more desirable N efficiency may be possible via optimizing density and N rate combination.

The first principle study of Ni{sub 2}ScGa and Ni{sub 2}TiGa

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

Özduran, Mustafa; Turgut, Kemal; Arikan, Nihat

2014-10-06

We computed the electronic structure, elastic moduli, vibrational properties, and Ni{sub 2}TiGa and Ni{sub 2}ScGa alloys in the cubic L2{sub 1} structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C{sub 11}, C{sub 12} and C{sub 44}. We calculated elastic constants in L2{sub 1} structure for Ni{sub 2}TiGa and Ni{sub 2}ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso programmore » package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and Sc 3d states for Ni{sub 2}TiGa, Ni 3d states and Sc 3d states for Ni{sub 2}ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni{sub 2}TiGa, 0.76 states/eV Cell for Ni{sub 2}ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L2{sub 1} phase is unstable since the phonon calculations have imagine modes.« less

Predictions for partial and monolayer coverages of O2 on graphite

NASA Technical Reports Server (NTRS)

Pan, R. P.; Etters, R. D.; Kobashi, K.; Chandrasekharan, V.

1982-01-01

Monolayer properties of O2 on graphite are calculated using a pattern recognition, optimization scheme. Equilibrium monolayers are predicted at two different densities with properties in agreement with recent X-ray diffraction, specific heat, and neutron scattering data. Properties of the extremely low density regime are calculated using a model based upon a distribution of two-dimensional O2 clusters. The results are consistent with experimental evidence.

Progranulin concentration in relation to bone mineral density among obese individuals.

PubMed

Milajerdi, Alireza; Maghbooli, Zhila; Mohammadi, Farzad; Hosseini, Banafsheh; Mirzaei, Khadijeh

2018-01-01

Adipose tissue, particularly visceral adipose tissue, secretes a variety of cytokines, among which progranulin is a glycoprotein related to the immune system. Along with other secreted proteins, progranulin may be associated with bone mineral density. The aim of this study was to find out whether there are associations between the progranulin and bone mineral density among obese people. This cross-sectional study was conducted on 244 obese participants (aged 22-52). Serum progranulin, high sensitive C-reactive protein, oxidised-low dencity lipoprotein, tumor necrosis factor-α, parathormone, vitamin D, and interleukins of 1 β, 4, 6, 10, 13, and 17 concentrations were measured. Anthropometric measurements, body composition and bone mineral density were also assessed. Serum progranulin was directly associated with interleukin-6 and interleukin-1β, while it had a negative association with interleukin-17 and tumor necrosis factor-α. We also observed a statistically significant direct association between progranulin concentration and visceral fat, abdominal fat, waist, abdominal and hip circumferences, hip T-score, and Z-score and T-score for the lumbar region. A partial correlation test has also shown a significant positive correlation regarding serum progranulin and the hip Z-score. Moreover, progranulin level is inversely associated with ospteopenia (P = 0.04 and CI: 0.17,0.96). Our study revealed that central obesity may be related to increased progranulin concentration. In addition, progranulin concentration was directly related to bone formation parameters, which indicates the protective effects of progranulin on bone density. Further studies are needed to clarify the exact mechanisms underlying these associations.

Temporal variations of electron density and temperature in Kr/Ne/H2 photoionized plasma induced by nanosecond pulses from extreme ultraviolet source

NASA Astrophysics Data System (ADS)

Saber, I.; Bartnik, A.; Wachulak, P.; Skrzeczanowski, W.; Jarocki, R.; Fiedorowicz, H.

2017-06-01

Spectral investigations of low-temperature photoionized plasmas created in a Kr/Ne/H2 gas mixture were performed. The low-temperature plasmas were generated by gas mixture irradiation using extreme ultraviolet pulses from a laser-plasma source. Emission spectra in the ultraviolet/visible range from the photoionized plasmas contained lines that mainly corresponded to neutral atoms and singly charged ions. Temporal variations in the plasma electron temperature and electron density were studied using different characteristic emission lines at various delay times. Results, based on Kr II lines, showed that the electron temperature decreased from 1.7 to 0.9 eV. The electron densities were estimated using different spectral lines at each delay time. In general, except for the Hβ line, in which the electron density decreased from 3.78 × 1016 cm-3 at 200 ns to 5.77 × 1015 cm-3 at 2000 ns, most of the electron density values measured from the different lines were of the order of 1015 cm-3 and decreased slightly while maintaining the same order when the delay time increased. The time dependences of the measured and simulated intensities of a spectral line of interest were also investigated. The validity of the partial or full local thermodynamic equilibrium (LTE) conditions in plasma was explained based on time-resolved electron density measurements. The partial LTE condition was satisfied for delay times in the 200 ns to 1500 ns range. The results are summarized, and the dominant basic atomic processes in the gas mixture photoionized plasma are discussed.

Control of particle and power exhaust in pellet fuelled ITER DT scenarios employing integrated models

NASA Astrophysics Data System (ADS)

Wiesen, S.; Köchl, F.; Belo, P.; Kotov, V.; Loarte, A.; Parail, V.; Corrigan, G.; Garzotti, L.; Harting, D.

2017-07-01

The integrated model JINTRAC is employed to assess the dynamic density evolution of the ITER baseline scenario when fuelled by discrete pellets. The consequences on the core confinement properties, α-particle heating due to fusion and the effect on the ITER divertor operation, taking into account the material limitations on the target heat loads, are discussed within the integrated model. Using the model one can observe that stable but cyclical operational regimes can be achieved for a pellet-fuelled ITER ELMy H-mode scenario with Q  =  10 maintaining partially detached conditions in the divertor. It is shown that the level of divertor detachment is inversely correlated with the core plasma density due to α-particle heating, and thus depends on the density evolution cycle imposed by pellet ablations. The power crossing the separatrix to be dissipated depends on the enhancement of the transport in the pedestal region being linked with the pressure gradient evolution after pellet injection. The fuelling efficacy of the deposited pellet material is strongly dependent on the E  ×  B plasmoid drift. It is concluded that integrated models like JINTRAC, if validated and supported by realistic physics constraints, may help to establish suitable control schemes of particle and power exhaust in burning ITER DT-plasma scenarios.

Turbulence evolution and transport behavior during current ramp-up in ITER-like plasmas on DIII-D

DOE PAGES

McKee, George R.; Austin, Max E.; Boedo, Jose A.; ...

2017-07-12

Low-wavenumber density fluctuations exhibit unique characteristics during the current ramp-up phase of ITER-like discharges that can partially explain the challenges of correctly modeling transport behavior and predicting global plasma parameters during this period. A strong interaction takes place between the evolving transport, safety factor (q) and kinetic profiles as well as the appearance and evolution of low-order rational surfaces. Density fluctuations from 0.75 < ρ < 0.9 are transiently reduced to exceptionally low levels during early times and from 0.8 < ρ < 0.9 at late times in the ramp-up in a manner that is different from behavior observed duringmore » steady-state plasma conditions with similar values of q 95. Turbulence is suppressed as low-order-rational q-surfaces enter the plasma; the local electron temperature likewise exhibits transient increases during these periods of reduced fluctuations indicating changes in transport that impact temperature and consequently the evolution of current density and plasma inductance. These observations can explain discrepancies between CORSICA modelling and the higher electron temperature found previously over the outer half radius. Comparison of turbulence properties with time-varying linear growth rates with GYRO and GENE demonstrate qualitative consistency with measured fluctuation levels, but calculations don’t exhibit reduced growth rates near low-order rational surfaces, which is inconsistent with experimental observations. Here, this indicates a mechanism that can contribute to reconciling observed turbulence behavior with transport models, allowing for the development of more accurate predictive tools.« less

Changes in per capita alcohol sales during the partial privatization of British Columbia's retail alcohol monopoly 2003-2008: a multi-level local area analysis.

PubMed

Stockwell, Tim; Zhao, Jinhui; Macdonald, Scott; Pakula, Basia; Gruenewald, Paul; Holder, Harold

2009-11-01

To investigate the independent effects on liquor sales of an increase in (a) the density of liquor outlets and (b) the proportion of liquor stores in private rather than government ownership in British Columbia between 2003/4 and 2007/8. The British Columbia Liquor Distribution Branch provided data on litres of ethanol sold through different types of outlets in 89 local health areas of the province by beverage type. Multi-level regression models were used to examine the relationship between per capita alcohol sales and outlet densities for different types of liquor outlet after adjusting for potential confounding social, economic and demographic factors as well as spatial and temporal autocorrelation. Liquor outlets in 89 local health areas of British Columbia, Canada. The number of private stores per 10,000 residents was associated significantly and positively with per capita sales of ethanol in beer, coolers, spirits and wine, while the reverse held for government liquor stores. Significant positive effects were also identified for the number of bars and restaurants per head of population. The percentage of liquor stores in private versus government ownership was also associated significantly with per capita alcohol sales when controlling for density of liquor stores and of on-premise outlets (P < 0.01). The trend towards privatisation of liquor outlets between 2003/04 and 2007/08 in British Columbia has contributed to increased per capita sales of alcohol and hence possibly also to increased alcohol-related harm.

Adsorption and dissociation of molecular oxygen on α-Pu (0 2 0) surface: A density functional study

NASA Astrophysics Data System (ADS)

Wang, Jianguang; Ray, Asok K.

2011-09-01

Molecular and dissociative oxygen adsorptions on the α-Pu (0 2 0) surface have been systematically studied using the full-potential linearized augmented-plane-wave plus local orbitals (FP-LAPW+lo) basis method and the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional. Chemisorption energies have been optimized for the distance of the admolecule from the Pu surface and the bond length of O-O atoms for four adsorption sites and three approaches of O 2 admolecule to the (0 2 0) surface. Chemisorption energies have been calculated at the scalar relativistic level with no spin-orbit coupling (NSOC) and at the fully relativistic level with spin-orbit coupling (SOC). Dissociative adsorptions are found at the two horizontal approaches (O 2 is parallel to the surface and perpendicular/parallel to a lattice vector). Hor2 (O 2 is parallel to the surface and perpendicular to a lattice vector) approach at the one-fold top site is the most stable adsorption site, with chemisorption energies of 8.048 and 8.415 eV for the NSOC and SOC cases, respectively, and an OO separation of 3.70 Å. Molecular adsorption occurs at the Vert (O 2 is vertical to the surface) approach of each adsorption site. The calculated work functions and net spin magnetic moments, respectively, increase and decrease in all cases upon chemisorption compared to the clean surface. The partial charges inside the muffin-tins, the difference charge density distributions, and the local density of states have been used to investigate the Pu-admolecule electronic structures and bonding mechanisms.

Turbulence evolution and transport behavior during current ramp-up in ITER-like plasmas on DIII-D

NASA Astrophysics Data System (ADS)

McKee, G. R.; Austin, M.; Boedo, J.; Bravenec, R.; Holland, C.; Jackson, G.; Luce, T. C.; Rhodes, T. L.; Rudakov, D.; Wang, G.; Yan, Z.; Zeng, L.; Zhao, Y.

2017-08-01

Low-wavenumber density fluctuations exhibit unique characteristics during the current ramp-up phase of ITER-like discharges that can partially explain the challenges of correctly modeling transport behavior and predicting global plasma parameters during this period. A strong interaction takes place between the evolving transport, safety factor (q) and kinetic profiles as well as the appearance and evolution of low-order rational surfaces. Density fluctuations from 0.75  <  ρ  <  0.9 are transiently reduced to exceptionally low levels during early times and from 0.8  <  ρ  <  0.9 at late times in the ramp-up in a manner that is different from behavior observed during steady-state plasma conditions with similar values of q 95. Turbulence is suppressed as low-order-rational q-surfaces enter the plasma; the local electron temperature likewise exhibits transient increases during these periods of reduced fluctuations indicating changes in transport that impact temperature and consequently the evolution of current density and plasma inductance. These observations can explain discrepancies between CORSICA modelling and the higher electron temperature found previously over the outer half radius. Comparison of turbulence properties with time-varying linear growth rates with GYRO and GENE demonstrate qualitative consistency with measured fluctuation levels, but calculations don’t exhibit reduced growth rates near low-order rational surfaces, which is inconsistent with experimental observations. This indicates a mechanism that can contribute to reconciling observed turbulence behavior with transport models, allowing for the development of more accurate predictive tools.

Unified percolation model for bipolaron-assisted organic magnetoresistance in the unipolar transport regime

NASA Astrophysics Data System (ADS)

Gao, Nan; Li, Ling; Lu, Nianduan; Xie, Changqing; Liu, Ming; Bässler, Heinz

2016-08-01

The fact that in organic semiconductors the Hubbard energy is usually positive appears to be at variance with a bipolaron model to explain magnetoresistance (MR) in those systems. Employing percolation theory, we demonstrate that a moderately positive U is indeed compatible with the bipolaron concept for MR in unipolar current flow, provided that the system is energetically disordered, and the density of states (DOS) distribution is partially filled, so that the Fermi level overlaps with tail states of the DOS. By exploring a broad parameter space, we show that MR becomes maximal around U =0 and even diminishes at large negative values of U because of spin independent bipolaron dissociation. Trapping effects and reduced dimension enhance MR.

Strength characteristics of light weight concrete blocks using mineral admixtures

NASA Astrophysics Data System (ADS)

Bhuvaneshwari, P.; Priyadharshini, U.; Gurucharan, S.; Mithunram, B.

2017-07-01

This paper presents an experimental study to investigate the characteristics of light weight concrete blocks. Cement was partially replaced with mineral admixtures like Fly ash (FA), limestone powder waste (LPW), Rice husk ash (RHA), sugarcane fiber waste (SCW) and Chrysopogonzizanioides (CZ). The maximum replacement level achieved was 25% by weight of cement and sand. Total of 56 cubes (150 mm x 150 mm x150 mm) and 18 cylinders (100mmφ and 50mm depth) were cast. The specimens being (FA, RHA, SCW, LPW, CZ, (FA-RHA), (FA-LPW), (FA-CZ), (LPW-CZ), (FA-SCW), (RHA-SCW)).Among the different combination, FA,FA-SCW,CZ,FA-CZ showed enhanced strength and durability, apart from achieving less density.

Facile NOx interconversion over preoxidized Ag(111)

NASA Astrophysics Data System (ADS)

Klacar, S.; Martin, N. M.; Gustafson, J.; Blomberg, S.; Liu, Z.; Axnanda, S.; Chang, R.; Lundgren, E.; Grönbeck, H.

2013-11-01

X-ray photoelectron spectroscopy and density functional theory calculations are used to investigate NO adsorption at low (100 K) and room temperature (RT) over preoxidized Ag(111). At 100 K, the data indicates presence of NO and N2O2, with little or no nitrite/nitrate formation. This is consistent with the calculated surface core level shifts and the pronounced barrier for nitrite formation. At RT, the recorded spectra indicate a complex interconversion between adsorbed species with an initial formation of a p(4 × 4) nitrate overlayer. With increasing NO pressure, the experimental results are best rationalized by partial nitrate decomposition into nitrites and subsequent NO physisorption, which leads to the formation of N2O3-like species.

Rovibrationally-Resolved Direct Photodissociation Through The Lyman And Werner Transitions Of H_{2}

NASA Astrophysics Data System (ADS)

Gay, Christopher; Stancil, P. C.

2008-03-01

Direct photodissociation cross sections have been obtained for the Lyman and Werner transitions of H2 using a combination of ab initio and experimentally derived potential curves and dipole transition moments. The partial cross sections have been evaluated for transitions from all 301 rovibrational levels (v'',J'') of the ground electronic state and over a wavelength range that extends from 10nm to the dissociation threshold for each particular rovibrational state. For UV-irradiated molecular gas with column densities of 1016-1019cm-2, direct photodissociation can compete with the Solomon process as an H2 destruction process. This research was supported by NASA grant NNG06GJ11G from the Astrophysics Theory Program.

Quasi-Particle Self-Consistent GW for Molecules.

PubMed

Kaplan, F; Harding, M E; Seiler, C; Weigend, F; Evers, F; van Setten, M J

2016-06-14

We present the formalism and implementation of quasi-particle self-consistent GW (qsGW) and eigenvalue only quasi-particle self-consistent GW (evGW) adapted to standard quantum chemistry packages. Our implementation is benchmarked against high-level quantum chemistry computations (coupled-cluster theory) and experimental results using a representative set of molecules. Furthermore, we compare the qsGW approach for five molecules relevant for organic photovoltaics to self-consistent GW results (scGW) and analyze the effects of the self-consistency on the ground state density by comparing calculated dipole moments to their experimental values. We show that qsGW makes a significant improvement over conventional G0W0 and that partially self-consistent flavors (in particular evGW) can be excellent alternatives.

Dextromethorphan upregulates osteoblast and osteoclast activity but does not attenuate ovariectomy-induced osteoporosis.

PubMed

Wu, Jia-Lin; Tsai, Wei-Yuan; Chen, Jian-Horng; Wong, Chih-Shung

2017-03-15

Study on the in vivo regulatory role of glutamate in osteoblast (OB) and osteoclast (OC) differentiation is less advanced. The present study investigated the effect of dextromethorphan (DXM), an N-methyl-d-aspartate receptors (NMDARs) antagonist, on osteoporosis development. In order to examine the role of glutamate in bone metabolism, ovariectomized (Ovx) female Wistar rats were injected three times per week for 8weeks with either saline, or 15μg/kg of β-estrodiol, or DXM (40mg/kg) intraperitoneally. Serum samples were collected every two weeks for measuring osteocalcin and C-terminal telopeptide of type I collagen (CTX-1) level. Rats were then sacrificed at week 8 and the femurs harvested for micro-CT scanning and mechanical strength. In saline-treated group, osteocalcin level significantly lower than that of sham-operated rats at 8weeks after operation, while CTX-1 levels were not affected. Estrogen treatment, as a positive control, partially inhibited the Ovx-induced reduction of osteocalcin serum level. DXM injection prevented the Ovx-induced reduction of osteocalcin expression and significantly upregulated CTX-1 expression. The micro-CT scan showed that the bone volume density decreased significantly in DXM treated rats compared to the sham-operated rats. In the mechanical strength assay, the maximum failure load for DXM treatment was significantly lower than the other groups. Treatment with DXM upregulated OB and OC markers in Ovx rats, however with a greater effect on the OC marker, and had no significant benefit on bone volume density or bone strength. Copyright © 2017 Elsevier Inc. All rights reserved.

Preliminary Evidence for Adipocytokine Signals in Skeletal Muscle Glucose Uptake.

PubMed

Kudoh, Akihiro; Satoh, Hiroaki; Hirai, Hiroyuki; Watanabe, Tsuyoshi; Shimabukuro, Michio

2018-01-01

The cross talk between the adipose tissue and insulin target tissues is a key mechanism for obesity-associated insulin resistance. However, the precise role of the interaction between the skeletal muscle and adipose tissue for insulin signaling and glucose uptake is questionable. L6 myocytes were co-cultured with or without 3T3-L1 adipocytes (~5 × 10 3 cells/cm 2 ) up to 24 h. Glucose uptake was evaluated by 2-[ 3 H] deoxyglucose uptake assay. Levels of mRNA expression of Glut1 and Glut4 and mitochondrial enzymes were analyzed by quantitative real-time reverse transcription polymerase chain reaction. Levels of Glut1 and Glut4 protein and phosphorylation of Akt (Ser473 and Thr308) were analyzed by immunoblotting. Study 1: co-culture with 3T3-L1 adipocytes increased glucose uptake in dose- and time-dependent manner in L6 myocytes under insulin-untreated conditions. When co-cultured with 3T3-L1 cells, reactive oxygen species production and levels of Glut1 mRNA and protein were increased in L6 cells, while these changes were abrogated and the glucose uptake partially inhibited by antioxidant treatment. Study 2: co-culture with 3T3-L1 adipocytes suppressed insulin-stimulated glucose uptake in L6 myocytes. Insulin-induced Akt phosphorylation at Ser473 decreased, which was proportional to 3T3-L1 density. Antioxidant treatment partially reversed this effect. Interactions between skeletal muscle and adipose tissues are important for glucose uptake under insulin-untreated or -treated condition through oxygen stress mechanism.

Fermi wave vector for the partially spin-polarized composite-fermion Fermi sea

NASA Astrophysics Data System (ADS)

Balram, Ajit C.; Jain, J. K.

2017-12-01

The fully spin-polarized composite-fermion (CF) Fermi sea at the half-filled lowest Landau level has a Fermi wave vector kF*=√{4 π ρe } , where ρe is the density of electrons or composite fermions, supporting the notion that the interaction between composite fermions can be treated perturbatively. Away from ν =1 /2 , the area is seen to be consistent with kF*=√{4 π ρe } for ν <1 /2 but kF*=√{4 π ρh } for ν >1 /2 , where ρh is the density of holes in the lowest Landau level. This result is consistent with particle-hole symmetry in the lowest Landau level. We investigate in this article the Fermi wave vector of the spin-singlet CF Fermi sea (CFFS) at ν =1 /2 , for which particle-hole symmetry is not a consideration. Using the microscopic CF theory, we find that for the spin-singlet CFFS the Fermi wave vectors for up- and down-spin CFFSs at ν =1 /2 are consistent with kF*↑,↓=√{4 π ρe↑,↓ } , where ρe↑=ρe↓=ρe/2 , which implies that the residual interactions between composite fermions do not cause a nonperturbative correction for spin-singlet CFFS either. Our results suggest the natural conjecture that for arbitrary spin polarization the CF Fermi wave vectors are given by kF*↑=√{4 π ρe↑ } and kF*↓=√{4 π ρe↓ } .

On the classification of scalar evolution equations with non-constant separant

NASA Astrophysics Data System (ADS)

Hümeyra Bilge, Ayşe; Mizrahi, Eti

2017-01-01

The ‘separant’ of the evolution equation u t   =  F, where F is some differentiable function of the derivatives of u up to order m, is the partial derivative \\partial F/\\partial {{u}m}, where {{u}m}={{\\partial}m}u/\\partial {{x}m} . As an integrability test, we use the formal symmetry method of Mikhailov-Shabat-Sokolov, which is based on the existence of a recursion operator as a formal series. The solvability of its coefficients in the class of local functions gives a sequence of conservation laws, called the ‘conserved densities’ {ρ(i)}, i=-1,1,2,3,\\ldots . We apply this method to the classification of scalar evolution equations of orders 3≤slant m≤slant 15 , for which {ρ(-1)}={≤ft[\\partial F/\\partial {{u}m}\\right]}-1/m} and {{ρ(1)} are non-trivial, i.e. they are not total derivatives and {ρ(-1)} is not linear in its highest order derivative. We obtain the ‘top level’ parts of these equations and their ‘top dependencies’ with respect to the ‘level grading’, that we defined in a previous paper, as a grading on the algebra of polynomials generated by the derivatives u b+i , over the ring of {{C}∞} functions of u,{{u}1},\\ldots,{{u}b} . In this setting b and i are called ‘base’ and ‘level’, respectively. We solve the conserved density conditions to show that if {ρ(-1)} depends on u,{{u}1},\\ldots,{{u}b}, then, these equations are level homogeneous polynomials in {{u}b+i},\\ldots,{{u}m} , i≥slant 1 . Furthermore, we prove that if {ρ(3)} is non-trivial, then {ρ(-1)}={≤ft(α ub2+β {{u}b}+γ \\right)}1/2} , with b≤slant 3 while if {{ρ(3)} is trivial, then {ρ(-1)}={≤ft(λ {{u}b}+μ \\right)}1/3} , where b≤slant 5 and α, β, γ, λ and μ are functions of u,\\ldots,{{u}b-1} . We show that the equations that we obtain form commuting flows and we construct their recursion operators that are respectively of orders 2 and 6 for non-trivial and trivial {{ρ(3)} respectively. Omitting lower order dependencies, we show that equations with non-trivial {ρ(3)} and b  =  3 are symmetries of the ‘essentially non-linear third order equation’ for trivial {ρ(3)} , the equations with b  =  5 are symmetries of a non-quasilinear fifth order equation obtained in previous work, while for b  =  3, 4 they are symmetries of quasilinear fifth order equations.

Strategic and Tactical Decision-Making Under Uncertainty

DTIC Science & Technology

2006-01-03

message passing algorithms. In recent work we applied this method to the problem of joint decoding of a low-density parity-check ( LDPC ) code and a partial...Joint Decoding of LDPC Codes and Partial-Response Channels." IEEE Transactions on Communications. Vol. 54, No. 7, 1149-1153, 2006. P. Pakzad and V...Michael I. Jordan PAGES U U U SAPR 20 19b. TELEPHONE NUMBER (Include area code ) 510/642-3806 Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18

Critical parameters, thermodynamic functions, and shock Hugoniot of aluminum fluid at high energy density

NASA Astrophysics Data System (ADS)

Zaghloul, Mofreh R.

2018-03-01

We present estimates of the critical properties, thermodynamic functions, and principal shock Hugoniot of hot dense aluminum fluid as predicted from a chemical model for the equation-of-state of hot dense, partially ionized and partially degenerate plasma. The essential features of strongly coupled plasma of metal vapors, such as multiple ionization, Coulomb interactions among charged particles, partial degeneracy, and intensive short range hard core repulsion are taken into consideration. Internal partition functions of neutral, excited, and multiply ionized species are carefully evaluated in a statistical-mechanically consistent way. Results predicted from the present model are presented, analyzed and compared with available experimental measurements and other theoretical predictions in the literature.

Infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide.

PubMed

Kong, Chang Yi; Siratori, Tomoya; Funazukuri, Toshitaka; Wang, Guosheng

2014-10-03

The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15-343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide. Copyright © 2014 Elsevier B.V. All rights reserved.

Density functional theory study of defects in unalloyed δ-Pu

DOE PAGES

Hernandez, S. C.; Freibert, F. J.; Wills, J. M.

2017-03-19

Using density functional theory, we explore in this paper various classical point and complex defects within the face-centered cubic unalloyed δ-plutonium matrix that are potentially induced from self-irradiation. For plutonium only defects, the most energetically stable defect is a distorted split-interstitial. Gallium, the δ-phase stabilizer, is thermodynamically stable as a substitutional defect, but becomes unstable when participating in a complex defect configuration. Finally, complex uranium defects may thermodynamically exist as uranium substitutional with neighboring plutonium interstitial and stabilization of uranium within the lattice is shown via partial density of states and charge density difference plots to be 5f hybridization betweenmore » uranium and plutonium.« less

Density functional theory study of defects in unalloyed δ-Pu

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

Hernandez, S. C.; Freibert, F. J.; Wills, J. M.

Using density functional theory, we explore in this paper various classical point and complex defects within the face-centered cubic unalloyed δ-plutonium matrix that are potentially induced from self-irradiation. For plutonium only defects, the most energetically stable defect is a distorted split-interstitial. Gallium, the δ-phase stabilizer, is thermodynamically stable as a substitutional defect, but becomes unstable when participating in a complex defect configuration. Finally, complex uranium defects may thermodynamically exist as uranium substitutional with neighboring plutonium interstitial and stabilization of uranium within the lattice is shown via partial density of states and charge density difference plots to be 5f hybridization betweenmore » uranium and plutonium.« less

Changes in bone density and bone markers in rhythmic gymnasts and ballet dancers: implications for puberty and leptin levels.

PubMed

Muñoz, María Teresa; de la Piedra, Concepción; Barrios, Vicente; Garrido, Guadalupe; Argente, Jesús

2004-10-01

Our aim was to compare physical activity and biochemical markers with bone mineral acquisition in rhythmic gymnasts and ballet dancers. Weight, height, body mass index, nutritional intake, bone age and menstrual histories were analyzed in nine rhythmic gymnasts, twelve ballet dancers and fourteen controls. Bone mineral density (BMD) was assessed by X-ray absorptiometry at the lumbar spine, hip and radius. Bone alkaline phosphatase (bAP) and amino-terminal propeptide of procollagen I (PNIP) in serum and urinary alpha-isomer of the carboxy-terminal telopeptide of collagen I (alpha-CTX) were measured. Bone age was delayed 2 years and mean age at menarche was 15+/-0.9 years in rhythmic gymnasts and 13.7+/-1 years in ballet dancers, compared with 12.5+/-1 years in controls. Trocanteric and femoral neck BMD was significantly higher in rhythmic gymnasts compared with ballet dancers and controls. Right forearm (non-loaded zone) BMD was significantly decreased in rhythmic gymnasts and ballet dancers compared with controls. All subjects had normal bAP and PNIP levels, but the alpha-CTX/creatinine (Cr) ratio was increased in rhythmic gymnasts (P<0.001) with an inverse correlation between right forearm BMD and the alpha-CTX/Cr ratio (r=-0.74, P<0.001). Serum leptin levels were decreased in rhythmic gymnasts and ballet dancers. Rhythmic gymnasts had a positive correlation between right forearm BMD and leptin levels (r=0.85, P<0.001). Decreased bone mass in rhythmic gymnasts could be partially explained by an increase in bone resorption. Serum leptin levels could be implicated in the pubertal delay and be a good marker of bone mass in these subjects.

Dislocation and Structural Studies at Metal-Metallic Glass Interface at Low Temperature

NASA Astrophysics Data System (ADS)

Gupta, Pradeep; Yedla, Natraj

2017-12-01

In this paper, molecular dynamics (MD) simulation deformation studies on the Al (metal)-Cu50Zr50 (metallic glass) model interface is carried out based on cohesive zone model. The interface is subjected to mode-I loading at a strain rate of 109 s-1 and temperature of 100 K. The dislocations reactions and evolution of dislocation densities during the deformation have been investigated. Atomic interactions between Al, Cu and Zr atoms are modeled using EAM (embedded atom method) potential, and a timestep of 0.002 ps is used for performing the MD simulations. A circular crack and rectangular notch are introduced at the interface to investigate the effect on the deformation behavior and fracture. Further, scale size effect is also investigated. The structural changes and evolution of dislocation density are also examined. It is found that the dominant deformation mechanism is by Shockley partial dislocation nucleation. Amorphization is observed in the Al regions close to the interface and occurs at a lower strain in the presence of a crack. The total dislocation density is found to be maximum after the first yield in both the perfect and defect interface models and is highest in the case of perfect interface with a density of 6.31 × 1017 m-2. In the perfect and circular crack defect interface models, it is observed that the fraction of Shockley partial dislocation density decreases, whereas that of strain rod dislocations increases with increase in strain.

Exact analytical solutions of continuity equation for electron beams precipitating in Coulomb collisions

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

Dobranskis, R. R.; Zharkova, V. V., E-mail: valentina.zharkova@northumbria.ac.uk

2014-06-10

The original continuity equation (CE) used for the interpretation of the power law energy spectra of beam electrons in flares was written and solved for an electron beam flux while ignoring an additional free term with an electron density. In order to remedy this omission, the original CE for electron flux, considering beam's energy losses in Coulomb collisions, was first differentiated by the two independent variables: depth and energy leading to partial differential equation for an electron beam density instead of flux with the additional free term. The analytical solution of this partial differential continuity equation (PDCE) is obtained bymore » using the method of characteristics. This solution is further used to derive analytical expressions for mean electron spectra for Coulomb collisions and to carry out numeric calculations of hard X-ray (HXR) photon spectra for beams with different parameters. The solutions revealed a significant departure of electron densities at lower energies from the original results derived from the CE for the flux obtained for Coulomb collisions. This departure is caused by the additional exponential term that appeared in the updated solutions for electron differential density leading to its faster decrease at lower energies (below 100 keV) with every precipitation depth similar to the results obtained with numerical Fokker-Planck solutions. The effects of these updated solutions for electron densities on mean electron spectra and HXR photon spectra are also discussed.« less

Characterization of Early Partial Seizure Onset: Frequency, Complexity and Entropy

PubMed Central

Jouny, Christophe C.; Bergey, Gregory K.

2011-01-01

Objective A clear classification of partial seizures onset features is not yet established. Complexity and entropy have been very widely used to describe dynamical systems, but a systematic evaluation of these measures to characterize partial seizures has never been performed. Methods Eighteen different measures including power in frequency bands up to 300Hz, Gabor atom density (GAD), Higuchi fractal dimension (HFD), Lempel-Ziv complexity, Shannon entropy, sample entropy, and permutation entropy, were selected to test sensitivity to partial seizure onset. Intracranial recordings from forty-five patients with mesial temporal, neocortical temporal and neocortical extratemporal seizure foci were included (331 partial seizures). Results GAD, Lempel-Ziv complexity, HFD, high frequency activity, and sample entropy were the most reliable measures to assess early seizure onset. Conclusions Increases in complexity and occurrence of high-frequency components appear to be commonly associated with early stages of partial seizure evolution from all regions. The type of measure (frequency-based, complexity or entropy) does not predict the efficiency of the method to detect seizure onset. Significance Differences between measures such as GAD and HFD highlight the multimodal nature of partial seizure onsets. Improved methods for early seizure detection may be achieved from a better understanding of these underlying dynamics. PMID:21872526

Li interactions with the B40 fullerene and its application in Li-ion batteries: DFT studies

NASA Astrophysics Data System (ADS)

Moradi, Morteza; Bagheri, Zargham; Bodaghi, Ali

2017-05-01

The interaction of Li and Li+ with a B40 all-boron fullerene was theoretically investigated at the B3LYP, and Minnesota 2006 levels of theory. It was found that, unexpectedly, the interaction Li+ cation with the electron deficient B40 fullerene is stronger than the Li atom. It indicates that the B40 fullerene does not act as a conventional Lewis acid because of its highly correlated structure. Frontier molecular orbitals, partial density of states, and natural bond orbital analyses were used to discuss this unusual behavior. Our calculations indicate that this behavior makes the B40 fullerene more appropriate for application in the Li-ion batteries as anode material. The calculated cell voltage is about 530 mV. Also, it was found that Hartree Fock (HF) exchange percentage of density functionals has a reverse effect on the adsorption energies of Li and Li+. This energy is increased and decreased, respectively, for Li+ and Li adsorptions by increasing %HF exchange. Finally, a potential energy surface for Li and Li+ penetration into B40 fullerene was predicted.

Comparison of spatiotemporal cortical activation pattern during visual perception of Korean, English, Chinese words: an event-related potential study.

PubMed

Kim, Kyung Hwan; Kim, Ja Hyun

2006-02-20

The aim of this study was to compare spatiotemporal cortical activation patterns during the visual perception of Korean, English, and Chinese words. The comparison of these three languages offers an opportunity to study the effect of written forms on cortical processing of visually presented words, because of partial similarity/difference among words of these languages, and the familiarity of native Koreans with these three languages at the word level. Single-character words and pictograms were excluded from the stimuli in order to activate neuronal circuitries that are involved only in word perception. Since a variety of cerebral processes are sequentially evoked during visual word perception, a high-temporal resolution is required and thus we utilized event-related potential (ERP) obtained from high-density electroencephalograms. The differences and similarities observed from statistical analyses of ERP amplitudes, the correlation between ERP amplitudes and response times, and the patterns of current source density, appear to be in line with demands of visual and semantic analysis resulting from the characteristics of each language, and the expected task difficulties for native Korean subjects.

Entropy-guided switching trimmed mean deviation-boosted anisotropic diffusion filter

NASA Astrophysics Data System (ADS)

Nnolim, Uche A.

2016-07-01

An effective anisotropic diffusion (AD) mean filter variant is proposed for filtering of salt-and-pepper impulse noise. The implemented filter is robust to impulse noise ranging from low to high density levels. The algorithm involves a switching scheme in addition to utilizing the unsymmetric trimmed mean/median deviation to filter image noise while greatly preserving image edges, regardless of impulse noise density (ND). It operates with threshold parameters selected manually or adaptively estimated from the image statistics. It is further combined with the partial differential equations (PDE)-based AD for edge preservation at high NDs to enhance the properties of the trimmed mean filter. Based on experimental results, the proposed filter easily and consistently outperforms the median filter and its other variants ranging from simple to complex filter structures, especially the known PDE-based variants. In addition, the switching scheme and threshold calculation enables the filter to avoid smoothing an uncorrupted image, and filtering is activated only when impulse noise is present. Ultimately, the particular properties of the filter make its combination with the AD algorithm a unique and powerful edge-preservation smoothing filter at high-impulse NDs.

Electron Radiation Damage of (alga) As-gaas Solar Cells

NASA Technical Reports Server (NTRS)

Loo, R.; Kamath, G. S.; Knechtli, R.

1979-01-01

Solar cells (2 cm by 2 cm (AlGa) As-GaAs cells) were fabricated and then subjected to irradiation at normal incidence by electrons. The influence of junction depth and n-type buffer layer doping level on the cell's resistance to radiation damage was investigated. The study shows that (1) a 0.3 micrometer deep junction results in lower damage to the cells than does a 0.5 micrometer junction, and (2) lowering the n buffer layer doping density does not improve the radiation resistance of the cell. Rather, lowering the doping density decreases the solar cell's open circuit voltage. Some preliminary thermal annealing experiments in vacuum were performed on the (AlGa)As-GaAs solar cells damaged by 1-MeV electron irradiation. The results show that cell performance can be expected to partially recover at 200 C with more rapid and complete recovery occurring at higher temperature. For a 0.5hr anneal at 400 C, 90% of the initial power is recovered. The characteristics of the (AlGa)As-GaAs cells both before and after irradiation are described.

Transport properties at fluids interfaces: a molecular study for a macroscopic modelling

NASA Astrophysics Data System (ADS)

Russo, Antonio; Morciano, Matteo; Sibley, David N.; Nold, Andreas; Goddard, Benjamin D.; Asinari, Pietro; Kalliadasis, Serafim

2017-11-01

Rapid developments in the field of micro- and nano-fluidics require detailed analysis of the properties of matter at the molecular level. But despite numerous works in the literature, appropriate macroscopic relations able to integrate a microscopic description of fluid and soft matter properties at liquid-vapour and multi-fluid interfaces are missing. As a consequence, studies on interfacial phenomena and micro-device designs often rely on oversimplified assumptions, e.g. that the viscosities can be considered constant across interfaces. In our work, we present non-equilibrium MD simulations to scrutinise efficiently and systematically, through the tools of statistical mechanics, the anisotropic properties of fluids, namely density variations, stress tensor, and shear viscosity, at the fluid interfaces between liquid and vapour and between two partially miscible fluids. Our analysis has led to the formulation of a general relation between shear viscosity and density variations validated for a wide spectrum of interfacial fluid problems. In addition, it provides a rational description of other interfacial quantities of interest, including surface tension and its origins, and more generally, it offers valuable insight of molecular transport phenomena at interfaces.

Production of ZrC Matrix for Use in Gas Fast Reactor Composite Fuels

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

Vasudevamurthy, Gokul; Knight, Travis W.; Roberts, Elwyn

2007-07-01

Zirconium carbide is being considered as a candidate for inert matrix material in composite nuclear fuel for Gas fast reactors due to its favorable characteristics. ZrC can be produced by the direct reaction of pure zirconium and graphite powders. Such a reaction is exothermic in nature. The reaction is self sustaining once initial ignition has been achieved. The heat released during the reaction is high enough to complete the reaction and achieve partial sintering without any external pressure applied. External heat source is required to achieve ignition of the reactants and maintain the temperature close to the adiabatic temperature tomore » achieve higher levels of sintering. External pressure is also a driving force for sintering. In the experiments described, cylindrical compacts of ZrC were produced by direct combustion reaction. External induction heating combined with varying amounts of external applied pressure was employed to achieve varying degrees of density/porosity. The effect of reactant particle size on the product characteristics was also studied. The samples were characterized for density/porosity, composition and microstructure. (authors)« less

Order in dense hydrogen at low temperatures

PubMed Central

Edwards, B.; Ashcroft, N. W.

2004-01-01

By increase in density, impelled by pressure, the electronic energy bands in dense hydrogen attain significant widths. Nevertheless, arguments can be advanced suggesting that a physically consistent description of the general consequences of this electronic structure can still be constructed from interacting but state-dependent multipoles. These reflect, in fact self-consistently, a disorder-induced localization of electron states partially manifesting the effects of proton dynamics; they retain very considerable spatial inhomogeneity (as they certainly do in the molecular limit). This description, which is valid provided that an overall energy gap has not closed, leads at a mean-field level to the expected quadrupolar coupling, but also for certain structures to the eventual emergence of dipolar terms and their coupling when a state of broken charge symmetry is developed. A simple Hamiltonian incorporating these basic features then leads to a high-density, low-temperature phase diagram that appears to be in substantial agreement with experiment. In particular, it accounts for the fact that whereas the phase I–II phase boundary has a significant isotope dependence, the phase II–III boundary has very little. PMID:15028839

The Root Cause of Post-Traumatic and Developmental Stress Disorder

DTIC Science & Technology

2014-10-01

cortex = mOFCtx) involving mushroom spines, 2) Increased density of stubby spines, suggesting that some mature mushroom spines have regressed to a more...and a trend for decreased mushroom spine density in PTSD (BA11), consistent with animal models. A subset of mature mushroom spines appear to have...been partially replaced by stubby spines. Stubby spines are less sophisticated than mushroom spines because they do not have necks, where modulatory

The Root Cause of Post-traumatic and Developmental Stress Disorder

DTIC Science & Technology

2015-10-01

mOFCtx) involving mushroom spines (Young et al., 2015), 2) Increased density of stubby spines, suggesting that some mature mushroom spines have...BA11 (mOFCtx) and a trend for decreased mushroom spine density in PTSD (BA11), consistent with animal models. A subset of mature mushroom spines...appear to have been partially replaced by stubby spines. Stubby spines are less sophisticated than mushroom spines because they do not have necks

Carbon carry capacity and carbon sequestration potential in China based on an integrated analysis of mature forest biomass.

PubMed

Liu, YingChun; Yu, GuiRui; Wang, QiuFeng; Zhang, YangJian; Xu, ZeHong

2014-12-01

Forests play an important role in acting as a carbon sink of terrestrial ecosystem. Although global forests have huge carbon carrying capacity (CCC) and carbon sequestration potential (CSP), there were few quantification reports on Chinese forests. We collected and compiled a forest biomass dataset of China, a total of 5841 sites, based on forest inventory and literature search results. From the dataset we extracted 338 sites with forests aged over 80 years, a threshold for defining mature forest, to establish the mature forest biomass dataset. After analyzing the spatial pattern of the carbon density of Chinese mature forests and its controlling factors, we used carbon density of mature forests as the reference level, and conservatively estimated the CCC of the forests in China by interpolation methods of Regression Kriging, Inverse Distance Weighted and Partial Thin Plate Smoothing Spline. Combining with the sixth National Forest Resources Inventory, we also estimated the forest CSP. The results revealed positive relationships between carbon density of mature forests and temperature, precipitation and stand age, and the horizontal and elevational patterns of carbon density of mature forests can be well predicted by temperature and precipitation. The total CCC and CSP of the existing forests are 19.87 and 13.86 Pg C, respectively. Subtropical forests would have more CCC and CSP than other biomes. Consequently, relying on forests to uptake carbon by decreasing disturbance on forests would be an alternative approach for mitigating greenhouse gas concentration effects besides afforestation and reforestation.

Quantum mechanical, spectroscopic studies (FT-IR, FT-Raman, NMR, UV) and normal coordinates analysis on 3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide

NASA Astrophysics Data System (ADS)

Muthu, S.; Uma Maheswari, J.; Sundius, Tom

2013-05-01

Famotidine (3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide) is a histamine H2-receptor antagonist that inhibits stomach acid production, and it is commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD/GORD). Quantum chemical calculations of the equilibrium geometry of famotidine in the ground state were carried out using density functional theory (DFT/B3LYP) with the 6-311G(d,p) basis set. In addition, harmonic vibrational frequencies, infrared intensities and Raman activities were calculated at the same level of theory. A detailed interpretation of the infrared and Raman spectrum of the drug is also reported. Theoretical simulations of the FT-IR, and FT-Raman spectra of the title compound have been calculated. Good correlations between the experimental 1H and 13C NMR chemical shifts and calculated GIAO shielding tensors were found. The results of the energy and oscillator strength calculations by time-dependent density functional theory (TD-DFT) supplement the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis were presented. The dipole moment, linear polarizability and first order hyperpolarizability values were also computed. The linear polarizability and first order hyperpolarizabilities of the studied molecule indicate that the compound is a good candidate for nonlinear optical materials.

Nonparametric model validations for hidden Markov models with applications in financial econometrics.

PubMed

Zhao, Zhibiao

2011-06-01

We address the nonparametric model validation problem for hidden Markov models with partially observable variables and hidden states. We achieve this goal by constructing a nonparametric simultaneous confidence envelope for transition density function of the observable variables and checking whether the parametric density estimate is contained within such an envelope. Our specification test procedure is motivated by a functional connection between the transition density of the observable variables and the Markov transition kernel of the hidden states. Our approach is applicable for continuous time diffusion models, stochastic volatility models, nonlinear time series models, and models with market microstructure noise.

Matrix Methods for Estimating the Coherence Functions from Estimates of the Cross-Spectral Density Matrix

DOE PAGES

Smallwood, D. O.

1996-01-01

It is shown that the usual method for estimating the coherence functions (ordinary, partial, and multiple) for a general multiple-input! multiple-output problem can be expressed as a modified form of Cholesky decomposition of the cross-spectral density matrix of the input and output records. The results can be equivalently obtained using singular value decomposition (SVD) of the cross-spectral density matrix. Using SVD suggests a new form of fractional coherence. The formulation as a SVD problem also suggests a way to order the inputs when a natural physical order of the inputs is absent.

RECOZ data reduction and analysis: Programs and procedures

NASA Technical Reports Server (NTRS)

Reed, E. I.

1984-01-01

The RECOZ data reduction programs transform data from the RECOZ photometer to ozone number density and overburden as a function of altitude. Required auxiliary data are the altitude profile versus time and for appropriate corrections to the ozone cross sections and scattering effects, air pressure and temperature profiles. Air temperature and density profiles may also be used to transform the ozone density versus geometric altitude to other units, such as to ozone partial pressure or mixing ratio versus pressure altitude. There are seven programs used to accomplish this: RADAR, LISTRAD, RAW OZONE, EDIT OZONE, MERGE, SMOOTH, and PROFILE.

Partially hydrolyzed guar gum as a potential prebiotic source.

PubMed

Mudgil, Deepak; Barak, Sheweta; Patel, Ami; Shah, Nihir

2018-06-01

Guar galactomannan was enzymatically hydrolyzed to obtain partially hydrolyzed guar gum which can be utilized as prebiotic source. In present study, growth of probiotics (Lactic Acid Bacteria strains) were studied with glucose, partially hydrolyzed guar gum and native guar gum. All the six strains were galactose &/or mannose positive using the API CHl 50 test. Almost all these strains showed an ability to assimilate partially hydrolyzed guar gum with respect to increase in optical density and viable cell count with concomitant decrease in the pH of the growth medium. Streptococcus thermophilus MD2 exhibited higher growth (7.78 log cfu/ml) while P. parvulus AI1 showed comparatively less growth (7.24 log cfu/ml) as compared to used lactobacillus and Weissella strains. Outcomes of the current study suggest that partially hydrolyzed guar can be considered as potential prebiotic compound that may further stimulate the growth of potentially probiotic bacteria or native gut microflora. Copyright © 2018 Elsevier B.V. All rights reserved.

Comparative effect of mechanical beating and nanofibrillation of cellulose on paper properties made from bagasse and softwood pulps.

PubMed

Afra, Elyas; Yousefi, Hossein; Hadilam, Mohamad Mahdi; Nishino, Takashi

2013-09-12

Cellulose fibers were fibrillated using mechanical beating (shearing refiner) and ultra-fine friction grinder, respectively. The fibrillated fibers were then used to make paper. Mechanical beating process created a partial skin fibrillation, while grinding turned fiber from micro to nanoscale through nanofibrillation mechanism. The partially fibrillated and nano fibrillated fibers had significant effects on paper density, tear strength, tensile strength and water drainage time. The effect of nanofibrillation on paper properties was quantitatively higher than that of mechanical beating. Paper sheets from nanofibrillated cellulose have a higher density, higher tensile strength and lower tear strength compared to those subjected to mechanical beating. Mechanical beating and nanofibrillation were both found to be promising fiber structural modifications. Long water drainage time was an important drawback of both fibrillation methods. Copyright © 2013 Elsevier Ltd. All rights reserved.

Two dimensional radial gas flows in atmospheric pressure plasma-enhanced chemical vapor deposition

NASA Astrophysics Data System (ADS)

Kim, Gwihyun; Park, Seran; Shin, Hyunsu; Song, Seungho; Oh, Hoon-Jung; Ko, Dae Hong; Choi, Jung-Il; Baik, Seung Jae

2017-12-01

Atmospheric pressure (AP) operation of plasma-enhanced chemical vapor deposition (PECVD) is one of promising concepts for high quality and low cost processing. Atmospheric plasma discharge requires narrow gap configuration, which causes an inherent feature of AP PECVD. Two dimensional radial gas flows in AP PECVD induces radial variation of mass-transport and that of substrate temperature. The opposite trend of these variations would be the key consideration in the development of uniform deposition process. Another inherent feature of AP PECVD is confined plasma discharge, from which volume power density concept is derived as a key parameter for the control of deposition rate. We investigated deposition rate as a function of volume power density, gas flux, source gas partial pressure, hydrogen partial pressure, plasma source frequency, and substrate temperature; and derived a design guideline of deposition tool and process development in terms of deposition rate and uniformity.

Phonon anharmonicity of monoclinic zirconia and yttrium-stabilized zirconia

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

Li, Chen W.; Smith, Hillary L.; Lan, Tian

2015-04-13

Inelastic neutron scattering measurements on monoclinic zirconia (ZrO 2) and 8 mol% yttrium-stabilized zirconia were performed at temperatures from 300 to 1373 ωK. We reported temperature-dependent phonon densities of states (DOS) and Raman spectra obtained at elevated temperatures. First-principles lattice dynamics calculations with density functional theory gave total and partial phonon DOS curves and mode Grüneisen parameters. These mode Grüneisen parameters were used to predict the experimental temperature dependence of the phonon DOS with partial success. However, substantial anharmonicity was found at elevated temperatures, especially for phonon modes dominated by the motions of oxygen atoms. Yttrium-stabilized zirconia (YSZ) was somewhatmore » more anharmonic and had a broader phonon spectrum at low temperatures, owing in part to defects in its structure. YSZ also has a larger vibrational entropy than monoclinic zirconia.« less

Influence of catalyst packing configuration on the discharge characteristics of dielectric barrier discharge reactors: A numerical investigation

NASA Astrophysics Data System (ADS)

Gadkari, Siddharth; Gu, Sai

2018-06-01

A two-dimensional numerical fluid model is developed for studying the influence of packing configurations on dielectric barrier discharge (DBD) characteristics. Discharge current profiles and time averaged electric field strength, electron number density, and electron temperature distributions are compared for the three DBD configurations, plain DBD with no packing, partially packed DBD, and fully packed DBD. The results show that a strong change in discharge behaviour occurs when a DBD is fully packed as compared to partial packing or no packing. While the average electric field strength and electron temperature of a fully packed DBD are higher relative to the other DBD configurations, the average electron density is substantially lower and may impede the DBD reactor performance under certain operating conditions. Possible scenarios of the synergistic effect of the combination of plasma with catalysis are also discussed.

Effect of partially ionized impurities and radiation on the effective critical electric field for runaway generation

NASA Astrophysics Data System (ADS)

Hesslow, L.; Embréus, O.; Wilkie, G. J.; Papp, G.; Fülöp, T.

2018-07-01

We derive a formula for the effective critical electric field for runaway generation and decay that accounts for the presence of partially ionized impurities in combination with synchrotron and bremsstrahlung radiation losses. We show that the effective critical field is drastically larger than the classical Connor–Hastie field, and even exceeds the value obtained by replacing the free electron density by the total electron density (including both free and bound electrons). Using a kinetic equation solver with an inductive electric field, we show that the runaway current decay after an impurity injection is expected to be linear in time and proportional to the effective critical electric field in highly inductive tokamak devices. This is relevant for the efficacy of mitigation strategies for runaway electrons since it reduces the required amount of injected impurities to achieve a certain current decay rate.

High hydrostatic pressure extract of garlic increases the HDL cholesterol level via up-regulation of apolipoprotein A-I gene expression in rats fed a high-fat diet.

PubMed

Lee, Seohyun; Joo, Hyunjin; Kim, Chong-Tai; Kim, In-Hwan; Kim, Yangha

2012-06-19

Cardiovascular disease (CVD) is the number one cause of mortality worldwide and a low high-density lipoprotein cholesterol (HDL-C) level is an important marker of CVD risk. Garlic (Allium sativum) has been widely used in the clinic for treatment of CVD and regulation of lipid metabolism. This study investigated the effects of a high hydrostatic pressure extract of garlic (HEG) on HDL-C level and regulation of hepatic apolipoprotein A-I (apoA-I) gene expression. Male Sprague-Dawley rats were divided into two groups and maintained on a high-fat control diet (CON) or high-fat control diet supplemented with high hydrostatic pressure extract of garlic (HEG) for 5 weeks. Changes in the expression of genes related to HDL-C metabolism were analyzed in liver, together with biometric and blood parameters. In the HEG group, the plasma triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) levels were significantly decreased in comparison with the CON group (P < 0.05). Dietary HEG also lowered the hepatic TG and total cholesterol (TC) levels compared to the CON group. While the plasma HDL-C level and mRNA level of hepatic apoA-I, which is one of primarily proteins of HDL-C particle, were significantly increased in the HEG group compared to the CON group (P < 0.05). The gene expression of ATP-binding cassette transporter A1 (ABCA1) and lecithin:cholesterol acyltransferase (LCAT), importantly involved in the biogenesis in HDL, were also up-regulated by dietary HEG. These results suggest that HEG ameliorates plasma lipid profiles and attenuates hepatic lipid accumulation in the high-fat fed rats. Our findings provides that the effects of HEG on the increase of the plasma HDL-C level was at least partially mediated by up-regulation of hepatic genes expression such as apoA-I, ABCA1, and LCAT in rats fed a high-fat diet.

Magnetic Evidence for a Partially Differentiated Carbonaceous Chondrite Parent Body and Possible Implications for Asteroid 21 Lutetia

NASA Astrophysics Data System (ADS)

Weiss, Benjamin; Carporzen, L.; Elkins-Tanton, L.; Shuster, D. L.; Ebel, D. S.; Gattacceca, J.; Binzel, R. P.

2010-10-01

The origin of remanent magnetization in the CV carbonaceous chondrite Allende has been a longstanding mystery. The possibility of a core dynamo like that known for achondrite parent bodies has been discounted because chondrite parent bodies are assumed to be undifferentiated. Here we report that Allende's magnetization was acquired over several million years (Ma) during metasomatism on the parent planetesimal in a > 20 microtesla field 8-9 Ma after solar system formation. This field was present too recently and directionally stable for too long to have been the generated by the protoplanetary disk or young Sun. The field intensity is in the range expected for planetesimal core dynamos (Weiss et al. 2010), suggesting that CV chondrites are derived from the outer, unmelted layer of a partially differentiated body with a convecting metallic core (Elkins-Tanton et al. 2010). This suggests that asteroids with differentiated interiors could be present today but masked under chondritic surfaces. In fact, CV chondrites are spectrally similar to many members of the Eos asteroid family whose spectral diversity has been interpreted as evidence for a partially differentiated parent asteroid (Mothe-Diniz et al. 2008). CV chondrite spectral and polarimetric data also resemble those of asteroid 21 Lutetia (e.g., Belskaya et al. 2010), recently encountered by the Rosetta spacecraft. Ground-based measurements of Lutetia indicate a high density of 2.4-5.1 g cm-3 (Drummond et al. 2010), while radar data seem to rule out a metallic surface composition (Shepard et al. 2008). If Rosetta spacecraft measurements confirm a high density and a CV-like surface composition for Lutetia, then we propose Lutetia may be an example of a partially differentiated carbonaceous chondrite parent body. Regardless, the very existence of primitive achondrites, which contain evidence of both relict chondrules and partial melting, are prima facie evidence for the formation of partially differentiated bodies.

Hypertriglyceridemia: a too long unfairly neglected major cardiovascular risk factor.

PubMed

Tenenbaum, Alexander; Klempfner, Robert; Fisman, Enrique Z

2014-12-04

The existence of an independent association between elevated triglyceride (TG) levels, cardiovascular (CV) risk and mortality has been largely controversial. The main difficulty in isolating the effect of hypertriglyceridemia on CV risk is the fact that elevated triglyceride levels are commonly associated with concomitant changes in high density lipoprotein (HDL), low density lipoprotein (LDL) and other lipoproteins. As a result of this problem and in disregard of the real biological role of TG, its significance as a plausible therapeutic target was unfoundedly underestimated for many years. However, taking epidemiological data together, both moderate and severe hypertriglyceridaemia are associated with a substantially increased long term total mortality and CV risk. Plasma TG levels partially reflect the concentration of the triglyceride-carrying lipoproteins (TRL): very low density lipoprotein (VLDL), chylomicrons and their remnants. Furthermore, hypertriglyceridemia commonly leads to reduction in HDL and increase in atherogenic small dense LDL levels. TG may also stimulate atherogenesis by mechanisms, such excessive free fatty acids (FFA) release, production of proinflammatory cytokines, fibrinogen, coagulation factors and impairment of fibrinolysis. Genetic studies strongly support hypertriglyceridemia and high concentrations of TRL as causal risk factors for CV disease. The most common forms of hypertriglyceridemia are related to overweight and sedentary life style, which in turn lead to insulin resistance, metabolic syndrome (MS) and type 2 diabetes mellitus (T2DM). Intensive lifestyle therapy is the main initial treatment of hypertriglyceridemia. Statins are a cornerstone of the modern lipids-modifying therapy. If the primary goal is to lower TG levels, fibrates (bezafibrate and fenofibrate for monotherapy, and in combination with statin; gemfibrozil only for monotherapy) could be the preferable drugs. Also ezetimibe has mild positive effects in lowering TG. Initial experience with en ezetimibe/fibrates combination seems promising. The recently released IMPROVE-IT Trial is the first to prove that adding a non-statin drug (ezetimibe) to a statin lowers the risk of future CV events. In conclusion, the classical clinical paradigm of lipids-modifying treatment should be changed and high TG should be recognized as an important target for therapy in their own right. Hypertriglyceridemia should be treated.

Joint level-set and spatio-temporal motion detection for cell segmentation.

PubMed

Boukari, Fatima; Makrogiannis, Sokratis

2016-08-10

Cell segmentation is a critical step for quantification and monitoring of cell cycle progression, cell migration, and growth control to investigate cellular immune response, embryonic development, tumorigenesis, and drug effects on live cells in time-lapse microscopy images. In this study, we propose a joint spatio-temporal diffusion and region-based level-set optimization approach for moving cell segmentation. Moving regions are initially detected in each set of three consecutive sequence images by numerically solving a system of coupled spatio-temporal partial differential equations. In order to standardize intensities of each frame, we apply a histogram transformation approach to match the pixel intensities of each processed frame with an intensity distribution model learned from all frames of the sequence during the training stage. After the spatio-temporal diffusion stage is completed, we compute the edge map by nonparametric density estimation using Parzen kernels. This process is followed by watershed-based segmentation and moving cell detection. We use this result as an initial level-set function to evolve the cell boundaries, refine the delineation, and optimize the final segmentation result. We applied this method to several datasets of fluorescence microscopy images with varying levels of difficulty with respect to cell density, resolution, contrast, and signal-to-noise ratio. We compared the results with those produced by Chan and Vese segmentation, a temporally linked level-set technique, and nonlinear diffusion-based segmentation. We validated all segmentation techniques against reference masks provided by the international Cell Tracking Challenge consortium. The proposed approach delineated cells with an average Dice similarity coefficient of 89 % over a variety of simulated and real fluorescent image sequences. It yielded average improvements of 11 % in segmentation accuracy compared to both strictly spatial and temporally linked Chan-Vese techniques, and 4 % compared to the nonlinear spatio-temporal diffusion method. Despite the wide variation in cell shape, density, mitotic events, and image quality among the datasets, our proposed method produced promising segmentation results. These results indicate the efficiency and robustness of this method especially for mitotic events and low SNR imaging, enabling the application of subsequent quantification tasks.

Trans fatty acids and cholesterol levels: An evidence map of the available science.

PubMed

Liska, DeAnn J; Cook, Chad M; Wang, Ding Ding; Gaine, P Courtney; Baer, David J

2016-12-01

High intakes of industrial trans fatty acids (iTFA) increase circulating low density lipoprotein cholesterol (LDL-C) levels, which has implicated iTFA in coronary heart disease (CHD) risk. Published data on iTFA and LDL-C, however, represent higher intake levels than the U.S. population currently consume. This study used state-of-the-art evidence mapping approaches to characterize the full body of literature on LDL-C and iTFA at low intake levels. A total of 32 independent clinical trials that included at least one intervention or control group with iTFA at ≤3%en were found. Findings indicated that a wide range of oils and interventions were used, limiting the ability to determine an isolated effect of iTFA intake. Few data points were found for iTFA at <3%en, with the majority of low-level exposures actually representing control group interventions containing non-partially hydrogenated (PHO) oils. Further, it appears that few dose-response data points are available to assess the relationship of low levels of iTFA, particularly from PHO exposure, and LDL-C. Therefore, limited evidence is available to determine the effect of iTFA at current consumption levels on CHD risk. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

The construction of a high-density linkage map for identifying SNP markers that are tightly linked to a nuclear-recessive major gene for male sterility in Cryptomeria japonica D. Don

PubMed Central

2012-01-01

Background High-density linkage maps facilitate the mapping of target genes and the construction of partial linkage maps around target loci to develop markers for marker-assisted selection (MAS). MAS is quite challenging in conifers because of their large, complex, and poorly-characterized genomes. Our goal was to construct a high-density linkage map to facilitate the identification of markers that are tightly linked to a major recessive male-sterile gene (ms1) for MAS in C. japonica, a species that is important in Japanese afforestation but which causes serious social pollinosis problems. Results We constructed a high-density saturated genetic linkage map for C. japonica using expressed sequence-derived co-dominant single nucleotide polymorphism (SNP) markers, most of which were genotyped using the GoldenGate genotyping assay. A total of 1261 markers were assigned to 11 linkage groups with an observed map length of 1405.2 cM and a mean distance between two adjacent markers of 1.1 cM; the number of linkage groups matched the basic chromosome number in C. japonica. Using this map, we located ms1 on the 9th linkage group and constructed a partial linkage map around the ms1 locus. This enabled us to identify a marker (hrmSNP970_sf) that is closely linked to the ms1 gene, being separated from it by only 0.5 cM. Conclusions Using the high-density map, we located the ms1 gene on the 9th linkage group and constructed a partial linkage map around the ms1 locus. The map distance between the ms1 gene and the tightly linked marker was only 0.5 cM. The identification of markers that are tightly linked to the ms1 gene will facilitate the early selection of male-sterile trees, which should expedite C. japonica breeding programs aimed at alleviating pollinosis problems without harming productivity. PMID:22424262

Plasma homocysteine is associated with increased oxidative stress and antioxidant enzyme activity in welders.

PubMed

Liu, Hung-Hsin; Shih, Tung-Sheng; Huang, Hsin-Ru; Huang, Shih-Chien; Lee, Lien-Hsiung; Huang, Yi-Chia

2013-01-01

The purpose of this study was to examine the association of vitamin B6 status and plasma homocysteine with oxidative stress and antioxidant capacities in welders. Workers were divided into either the welding exposure group (n = 57) or the nonexposure controls (n = 42) based on whether they were employed as welders. There were no significant differences in vitamin B₆ status and plasma homocysteine concentration between the welding exposure group and the nonexposure controls. The welding exposure group had significantly higher levels of oxidized low-density lipoprotein cholesterol and lower erythrocyte glutathione concentration and superoxide dismutase (SOD) activities when compared to nonexposure controls. Plasma pyridoxal 5'-phosphate concentration did not correlate with oxidative stress indicators or antioxidant capacities in either group. However, plasma homocysteine significantly correlated with total antioxidant capacity (TAC) (partial r(s) = -0.34, P < 0.05) and erythrocyte SOD activities (partial r(s) = 0.29, P < 0.05) after adjusting for potential confounders in the welding exposure group. In the welding exposure group, adequate vitamin B₆ status was not associated with oxidative stress or antioxidant capacities. However, elevated plasma homocysteine seemed to be a major contributing factor to antioxidant capacities (TAC and erythrocyte SOD activities) in welders.

Twist phase-induced characteristics changes of a radially polarized Gaussian Schell-Model beam in a uniaxial crystal orthogonal to the optical axis

NASA Astrophysics Data System (ADS)

Cao, Pengfei; Fu, Wenyu

2017-10-01

Based on the extended Huygens-Fresnel integral formula and unified theory of coherence and polarization, we obtained the cross-spectral density matrix elements for a radially polarized partially coherent twist (RPPCT) beam in a uniaxial crystal. Moreover, compared with free space, we explore numerically the evolution properties of a RPPCT beam in a uniaxial crystal. The calculation results show that the evolution properties of a RPPCT beam in crystals are substantially different from its properties in free space. These properties in crystals are mainly determined by the twist factor and the ratio of extraordinary index to ordinary refractive index. In a uniaxial crystal, the distribution of the intensity of a RPPCT beam all exhibits non-circular symmetry, and these distributions change with twist factor and the ratio of extraordinary index to ordinary refractive index. The twist factor affects their rotation orientation angles, and the ratio of extraordinary index to ordinary refractive index impacts their twisted levels. This novel characteristics can be used for free-space optical communications, particle manipulation and nonlinear optics, where partially coherent beam with controlled profile and twist factor are required.

Hierarchical heuristic search using a Gaussian mixture model for UAV coverage planning.

PubMed

Lin, Lanny; Goodrich, Michael A

2014-12-01

During unmanned aerial vehicle (UAV) search missions, efficient use of UAV flight time requires flight paths that maximize the probability of finding the desired subject. The probability of detecting the desired subject based on UAV sensor information can vary in different search areas due to environment elements like varying vegetation density or lighting conditions, making it likely that the UAV can only partially detect the subject. This adds another dimension of complexity to the already difficult (NP-Hard) problem of finding an optimal search path. We present a new class of algorithms that account for partial detection in the form of a task difficulty map and produce paths that approximate the payoff of optimal solutions. The algorithms use the mode goodness ratio heuristic that uses a Gaussian mixture model to prioritize search subregions. The algorithms search for effective paths through the parameter space at different levels of resolution. We compare the performance of the new algorithms against two published algorithms (Bourgault's algorithm and LHC-GW-CONV algorithm) in simulated searches with three real search and rescue scenarios, and show that the new algorithms outperform existing algorithms significantly and can yield efficient paths that yield payoffs near the optimal.

An equation of state for partially ionized plasmas: The Coulomb contribution to the free energy

DOE PAGES

Kilcrease, D. P.; Colgan, J.; Hakel, P.; ...

2015-06-20

We have previously developed an equation of state (EOS) model called ChemEOS (Hakel and Kilcrease, Atomic Processes in Plasmas, Eds., J. Cohen et al., AIP, 2004) for a plasma of interacting ions, atoms and electrons. It is based on a chemical picture of the plasma and is derived from an expression for the Helmholtz free energy of the interacting species. All other equilibrium thermodynamic quantities are then obtained by minimizing this free energy subject to constraints, thus leading to a thermodynamically consistent EOS. The contribution to this free energy from the Coulomb interactions among the particles is treated using themore » method of Chabrier and Potekhin (Phys. Rev. E 58, 4941 (1998)) which we have adapted for partially ionized plasmas. This treatment is further examined and is found to give rise to unphysical behavior for various elements at certain values of the density and temperature where the Coulomb coupling begins to become significant and the atoms are partially ionized. We examine the source of this unphysical behavior and suggest corrections that produce acceptable results. The sensitivity of the thermodynamic properties and frequency-dependent opacity of iron is examined with and without these corrections. Lastly, the corrected EOS is used to determine the fractional ion populations and level populations for a new generation of OPLIB low-Z opacity tables currently being prepared at Los Alamos National Laboratory with the ATOMIC code.« less

Partial genetic deletion of neuregulin 1 modulates the effects of stress on sensorimotor gating, dendritic morphology, and HPA axis activity in adolescent mice.

PubMed

Chohan, Tariq W; Boucher, Aurelie A; Spencer, Jarrah R; Kassem, Mustafa S; Hamdi, Areeg A; Karl, Tim; Fok, Sandra Y; Bennett, Maxwell R; Arnold, Jonathon C

2014-11-01

Stress has been linked to the pathogenesis of schizophrenia. Genetic variation in neuregulin 1 (NRG1) increases the risk of developing schizophrenia and may help predict which high-risk individuals will transition to psychosis. NRG1 also modulates sensorimotor gating, a schizophrenia endophenotype. We used an animal model to demonstrate that partial genetic deletion of Nrg1 interacts with stress to promote neurobehavioral deficits of relevance to schizophrenia. Nrg1 heterozygous (HET) mice displayed greater acute stress-induced anxiety-related behavior than wild-type (WT) mice. Repeated stress in adolescence disrupted the normal development of higher prepulse inhibition of startle selectively in Nrg1 HET mice but not in WT mice. Further, repeated stress increased dendritic spine density in pyramidal neurons of the medial prefrontal cortex (mPFC) selectively in Nrg1 HET mice. Partial genetic deletion of Nrg1 also modulated the adaptive response of the hypothalamic-pituitary-adrenal axis to repeated stress, with Nrg1 HET displaying a reduced repeated stress-induced level of plasma corticosterone than WT mice. Our results demonstrate that Nrg1 confers vulnerability to repeated stress-induced sensorimotor gating deficits, dendritic spine growth in the mPFC, and an abberant endocrine response in adolescence. © The Author 2014. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Exploring Early Stages of the Chemical Unfolding of Proteins at the Proteome Scale

PubMed Central

Candotti, Michela; Pérez, Alberto; Ferrer-Costa, Carles; Rueda, Manuel; Meyer, Tim; Gelpí, Josep Lluís; Orozco, Modesto

2013-01-01

After decades of using urea as denaturant, the kinetic role of this molecule in the unfolding process is still undefined: does urea actively induce protein unfolding or passively stabilize the unfolded state? By analyzing a set of 30 proteins (representative of all native folds) through extensive molecular dynamics simulations in denaturant (using a range of force-fields), we derived robust rules for urea unfolding that are valid at the proteome level. Irrespective of the protein fold, presence or absence of disulphide bridges, and secondary structure composition, urea concentrates in the first solvation shell of quasi-native proteins, but with a density lower than that of the fully unfolded state. The presence of urea does not alter the spontaneous vibration pattern of proteins. In fact, it reduces the magnitude of such vibrations, leading to a counterintuitive slow down of the atomic-motions that opposes unfolding. Urea stickiness and slow diffusion is, however, crucial for unfolding. Long residence urea molecules placed around the hydrophobic core are crucial to stabilize partially open structures generated by thermal fluctuations. Our simulations indicate that although urea does not favor the formation of partially open microstates, it is not a mere spectator of unfolding that simply displaces to the right of the folded←→unfolded equilibrium. On the contrary, urea actively favors unfolding: it selects and stabilizes partially unfolded microstates, slowly driving the protein conformational ensemble far from the native one and also from the conformations sampled during thermal unfolding. PMID:24348236

A DFT approach to discriminate the antagonist and partial agonist activity of ligands binding to the NMDA receptor

NASA Astrophysics Data System (ADS)

Haslak, Zeynep Pinar; Bozkurt, Esra; Dutagaci, Bercem; De Proft, Frank; Aviyente, Viktorya; De Vleeschouwer, Freija

2018-02-01

The activation of N-methyl-D-aspartate receptors is found to be intimately associated with neurodegenerative diseases which make them promising therapeutic targets. Despite the significantly increasing multidisciplinary interests centred on this ionotropic channel, design of new ligands with intended functional activity remains a great challenge. In this article, a computational study based on density functional theory is presented to understand the structural factors of ligands determining their function as antagonists and partial agonists. With this aim, the GluN1 subunit is chosen as being one of the essential components in the activation mechanism, and quantum chemical calculations are implemented for 30 antagonists and 30 partial agonists known to bind to this subunit with different binding affinities. Several quantum chemical descriptors are investigated which might unlock the difference between antagonists and partial agonists.

Quantification of brain tissue through incorporation of partial volume effects

NASA Astrophysics Data System (ADS)

Gage, Howard D.; Santago, Peter, II; Snyder, Wesley E.

1992-06-01

This research addresses the problem of automatically quantifying the various types of brain tissue, CSF, white matter, and gray matter, using T1-weighted magnetic resonance images. The method employs a statistical model of the noise and partial volume effect and fits the derived probability density function to that of the data. Following this fit, the optimal decision points can be found for the materials and thus they can be quantified. Emphasis is placed on repeatable results for which a confidence in the solution might be measured. Results are presented assuming a single Gaussian noise source and a uniform distribution of partial volume pixels for both simulated and actual data. Thus far results have been mixed, with no clear advantage being shown in taking into account partial volume effects. Due to the fitting problem being ill-conditioned, it is not yet clear whether these results are due to problems with the model or the method of solution.

Electronic structure and partial charge distribution of doxorubicin under different molecular environments

NASA Astrophysics Data System (ADS)

Poudel, Lokendra

Doxorubicin (trade name Adriamycin, abbreviated DOX) is a well-known an- thracyclic chemotherapeutic used in treating a variety of cancers including acute leukemia, lymphoma, multiple myeloma, and a range of stomach, lung, bladder, bone, breast, and ovarian cancers. The purpose of the present work is to study electronic structure, partial charge distribution and interaction energy of DOX under different environments. It provides a framework for better understanding of bioactivity of DOX with DNA. While in this work, we focus on DOX -- DNA interactions; the obtained knowledge could be translated to other drug -- target interactions or biomolecular interactions. The electronic structure and partial charge distribution of DOX in three dierent molecular environments: isolated, solvated, and intercalated into a DNA complex,were studied by rst principles density functional methods. It is shown that the addition of solvating water molecules to DOX and the proximity and interaction with DNA has a signicant impact on the electronic structure as well as the partial charge distribution. The calculated total partial charges for DOX in the three models are 0.0, +0.123 and -0.06 electrons for the isolated, solvated, and intercalated state, respectively. Furthermore, by using the more accurate ab initio partial charge values on every atom in the models, signicant improvement in estimating the DOX-DNA interaction energy is obtained in conjunction with the NAnoscale Molecular Dynamics (NAMD) code. The electronic structure of the DOX-DNA is further elucidated by resolving the total density of states (TDOS) into dierent functional groups of DOX, DNA, water, co-crystallized Spermine molecule, and Na ions. The surface partial charge distribution in the DOX-DNA is calculated and displayed graphically. We conclude that the presence of the solvent as well as the details of the interaction geometry matter greatly in the determination of the stability of the DOX complexion. Ab initio calculations on realistic models are an important step towards a more accurate description of biomolecular interaction and in the eventual understanding of long-range interactions in biomolecular systems.

The Effect of Fe-Ti-rich Cumulate Overturn on Evolution of the Lunar Interior

NASA Astrophysics Data System (ADS)

Mallik, A.; Ejaz, T.; Shcheka, S.; Garapic, G.; Petitgirard, S.; Blanchard, I.

2017-12-01

The last 5% of magma ocean crystallized Fe-Ti rich cumulates (FTC) emplaced below the anorthitic crust [1]. Due to gravitational instability, FTC underwent diapiric downwelling [2], associated with overturn of the lunar mantle. Petrological studies on Apollo basalts with variable TiO2 place their sources between 1.5-3 GPa. This indicates the presence of heterogeneous Ti-rich domains in the lunar interior which could either be produced by inefficient overturn and mixing [3], or due to post-overturn upwelling of FTC from the core-mantle boundary (CMB) [4]. Also, a seismically attenuating layer at the CMB ( 4.5 GPa) maybe associated with partial melt of overturned FTC [5]. Thus, it is important to investigate the phase equilibria of FTC with and without assimilation with the surrounding mantle, to understand better the effect of the overturn process on lunar evolution. We performed phase equilibria experiments at 2 and 4.5 GPa, 1230 to 1700 °C using a multi-anvil apparatus on FTC and a 1:1 mixture of FTC and mantle composition. FTC produced Fe-Ti rich (FeO 13-26 wt.%, TiO2 11-18 wt.%), Mg-poor (MgO 6-10 wt.%) basalts with residues of clinopyroxene+quartz+Fe-metal±spinel, while the mixture of FTC and mantle produced Fe-Ti-Mg rich (FeO 10-13 wt.%, TiO2 5-11 wt.% and MgO 20-30 wt.%) basalts with residues of orthopyroxene+olivine+Fe-metal±spinel±garnet. We find that partial melting of overturned cumulates within the lunar mantle can reproduce certain chemical attributes of Apollo high Ti basalts. Also, to test whether the partial melt of overturned cumulates can be stable at the CMB to produce the attenuating layer, we estimated the densities of these melt compositions using the published range of KT and K' of high Fe-Ti picrites. We find that the densities obtained from the published spread in K' and KT values yield inconclusive results about the stability of these partial melts at the CMB. This is being resolved by in-situ experimental determination of the densities of the high Fe-Ti melt compositions, currently underway. If these partial melts are indeed stable at the CMB, they bracket the present-day CMB temperature between 1300-1490 °C (5 to 30% partial melting [5]).[1] Snyder et al. (1992), GCA [2] Hess & Permentier (1995), EPSL [3] Brown & Grove (2015), GCA [4] Zhong et al. (2000), EPSL [5] Weber et al. (2011), Science

Genetic and Dynamic Analyses of Murine Peak Bone Density

DTIC Science & Technology

1999-10-01

DAMD17-96-1-6309 differences, the location of bone regulatory genes with strong and modifier effects , the mode of inheritance for each gene, the...estimate the cortical cross-sectional area, most likely due to partial volume effects . Thus, the high density bone area was consistently estimated to be...significant or highly significant linkage with BMD; b) 9 Beamer, WG DAMD17-96-1-6309 none of the loci exhibited significant interaction effects by ANOVA

AC Loss Analysis of MgB2-Based Fully Superconducting Machines

NASA Astrophysics Data System (ADS)

Feddersen, M.; Haran, K. S.; Berg, F.

2017-12-01

Superconducting electric machines have shown potential for significant increase in power density, making them attractive for size and weight sensitive applications such as offshore wind generation, marine propulsion, and hybrid-electric aircraft propulsion. Superconductors exhibit no loss under dc conditions, though ac current and field produce considerable losses due to hysteresis, eddy currents, and coupling mechanisms. For this reason, many present machines are designed to be partially superconducting, meaning that the dc field components are superconducting while the ac armature coils are conventional conductors. Fully superconducting designs can provide increases in power density with significantly higher armature current; however, a good estimate of ac losses is required to determine the feasibility under the machines intended operating conditions. This paper aims to characterize the expected losses in a fully superconducting machine targeted towards aircraft, based on an actively-shielded, partially superconducting machine from prior work. Various factors are examined such as magnet strength, operating frequency, and machine load to produce a model for the loss in the superconducting components of the machine. This model is then used to optimize the design of the machine for minimal ac loss while maximizing power density. Important observations from the study are discussed.

First-principles studies of electronic, transport and bulk properties of pyrite FeS2

NASA Astrophysics Data System (ADS)

Banjara, Dipendra; Malozovsky, Yuriy; Franklin, LaShounda; Bagayoko, Diola

2018-02-01

We present results from first principle, local density approximation (LDA) calculations of electronic, transport, and bulk properties of iron pyrite (FeS2). Our non-relativistic computations employed the Ceperley and Alder LDA potential and the linear combination of atomic orbitals (LCAO) formalism. The implementation of the LCAO formalism followed the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). We discuss the electronic energy bands, total and partial densities of states, electron effective masses, and the bulk modulus. Our calculated indirect band gap of 0.959 eV (0.96), using an experimental lattice constant of 5.4166 Å, at room temperature, is in agreement with the measured indirect values, for bulk samples, ranging from 0.84 eV to 1.03 ± 0.05 eV. Our calculated bulk modulus of 147 GPa is practically in agreement with the experimental value of 145 GPa. The calculated, partial densities of states reproduced the splitting of the Fe d bands to constitute the dominant upper most valence and lower most conduction bands, separated by the generally accepted, indirect, experimental band gap of 0.95 eV.

Continuum description of solvent dielectrics in molecular-dynamics simulations of proteins

NASA Astrophysics Data System (ADS)

Egwolf, Bernhard; Tavan, Paul

2003-02-01

We present a continuum approach for efficient and accurate calculation of reaction field forces and energies in classical molecular-dynamics (MD) simulations of proteins in water. The derivation proceeds in two steps. First, we reformulate the electrostatics of an arbitrarily shaped molecular system, which contains partially charged atoms and is embedded in a dielectric continuum representing the water. A so-called fuzzy partition is used to exactly decompose the system into partial atomic volumes. The reaction field is expressed by means of dipole densities localized at the atoms. Since these densities cannot be calculated analytically for general systems, we introduce and carefully analyze a set of approximations in a second step. These approximations allow us to represent the dipole densities by simple dipoles localized at the atoms. We derive a system of linear equations for these dipoles, which can be solved numerically by iteration. After determining the two free parameters of our approximate method we check its quality by comparisons (i) with an analytical solution, which is available for a perfectly spherical system, (ii) with forces obtained from a MD simulation of a soluble protein in water, and (iii) with reaction field energies of small molecules calculated by a finite difference method.

Self-Consistent Determination of Atomic Charges of Ionic Liquid through a Combination of Molecular Dynamics Simulation and Density Functional Theory.

PubMed

Ishizuka, Ryosuke; Matubayasi, Nobuyuki

2016-02-09

A self-consistent scheme is developed to determine the atomic partial charges of ionic liquid. Molecular dynamics (MD) simulation was conducted to sample a set of ion configurations, and these configurations were subject to density functional theory (DFT) calculations to determine the partial charges. The charges were then averaged and used as inputs for the subsequent MD simulation, and MD and DFT calculations were repeated until the MD results are not altered any more. We applied this scheme to 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imide ([C1mim][NTf2]) and investigated its structure and dynamics as a function of temperature. At convergence, the average ionic charges were ±0.84 e at 350 K due to charge transfer among ions, where e is the elementary charge, while the reduced ionic charges do not affect strongly the density of [C1mim][NTf2] and radial distribution function. Instead, major effects are found on the energetics and dynamics, with improvements of the overestimated heat of vaporization and the too slow motions of ions observed in MD simulations using commonly used force fields.

Reuse of waste iron as a partial replacement of sand in concrete.

PubMed

Ismail, Zainab Z; Al-Hashmi, Enas A

2008-11-01

One of the major environmental issues in Iraq is the large quantity of waste iron resulting from the industrial sector which is deposited in domestic waste and in landfills. A series of 109 experiments and 586 tests were carried out in this study to examine the feasibility of reusing this waste iron in concrete. Overall, 130 kg of waste iron were reused to partially replace sand at 10%, 15%, and 20% in a total of 1703 kg concrete mixtures. The tests performed to evaluate waste-iron concrete quality included slump, fresh density, dry density, compressive strength, and flexural strength tests: 115 cubes of concrete were molded for the compressive strength and dry density tests, and 87 prisms were cast for the flexural strength tests. This work applied 3, 7, 14, and 28 days curing ages for the concrete mixes. The results confirm that reuse of solid waste material offers an approach to solving the pollution problems that arise from an accumulation of waste in a production site; in the meantime modified properties are added to the concrete. The results show that the concrete mixes made with waste iron had higher compressive strengths and flexural strengths than the plain concrete mixes.

Direct-method SAD phasing with partial-structure iteration: towards automation.

PubMed

Wang, J W; Chen, J R; Gu, Y X; Zheng, C D; Fan, H F

2004-11-01

The probability formula of direct-method SAD (single-wavelength anomalous diffraction) phasing proposed by Fan & Gu (1985, Acta Cryst. A41, 280-284) contains partial-structure information in the form of a Sim-weighting term. Previously, only the substructure of anomalous scatterers has been included in this term. In the case that the subsequent density modification and model building yields only structure fragments, which do not straightforwardly lead to the complete solution, the partial structure can be fed back into the Sim-weighting term of the probability formula in order to strengthen its phasing power and to benefit the subsequent automatic model building. The procedure has been tested with experimental SAD data from two known proteins with copper and sulfur as the anomalous scatterers.

Improved toughness of silicon carbide

NASA Technical Reports Server (NTRS)

Palm, J. A.

1976-01-01

Impact energy absorbing layers (EALs) comprised of partially densified silicon carbide were formed in situ on fully sinterable silicon carbide substrates. After final sintering, duplex silicon carbide structures resulted which were comprised of a fully sintered, high density silicon carbide substrate or core, overlayed with an EAL of partially sintered silicon carbide integrally bonded to its core member. Thermal cycling tests proved such structures to be moderately resistant to oxidation and highly resistant to thermal shock stresses. The strength of the developed structures in some cases exceeded but essentially it remained the same as the fully sintered silicon carbide without the EAL. Ballistic impact tests indicated that substantial improvements in the toughness of sintered silicon carbide were achieved by the use of the partially densified silicon carbide EALs.

Electronic and thermal properties of germanene and stanene by first-principles calculations

NASA Astrophysics Data System (ADS)

Jomehpour Zaveh, S.; Roknabadi, M. R.; Morshedloo, T.; Modarresi, M.

2016-03-01

The electronic, vibrational and thermal properties of germanene and stanene have been investigated based on density functional theory (DFT) and density functional perturbation theory (DFPT). The electronic band structure, total and partial density of states and phonon dispersion spectrum and states are analyzed. The phonon spectrum is positive for all modes in the first Brillouin zone and there is a phonon energy band gap between acoustic and optical modes which is around 50 cm-1 for both structure. The constant-volume specific heats of two structures are calculated by using phonon spectrum and density of states. The spin-orbit coupling (SOC) opens a direct energy band gap at the Dirac point, softens phonon spectrum and decreases phonon group velocity of ZA mode.

The nature of crustal reflectivity at the southwest Iberian margin

NASA Astrophysics Data System (ADS)

Buffett, G. G.; Torne, M.; Carbonell, R.; Melchiorre, M.; Vergés, J.; Fernàndez, M.

2017-11-01

Reprocessing of multi-channel seismic reflection data acquired over the northern margin of the Gulf of Cádiz (SW Iberian margin) places new constraints on the upper crustal structure of the Guadalquivir-Portimão Bank. The data presented have been processed with optimized stacking and interval velocity models, a better approach to multiple attenuation, preserved amplitude information to derive the nature of seismic reflectivity, and accurate time-to-depth conversion after migration. The reprocessed data reveal a bright upper crustal reflector just underneath the Paleozoic basement that spatially coincides with the local positive free-air gravity high called the Gulf of Cádiz Gravity High. To investigate the nature of this reflector and to decipher whether it could be associated with pieces of mantle material emplaced at upper crustal levels, we calculated its reflection coefficient and compared it to a buried high-density ultramafic body (serpentinized peridotite) at the Gorringe Bank. Its reflection coefficient ratio with respect to the sea floor differs by only 4.6% with that calculated for the high-density ultramafic body of the Gorringe Bank, while it differs by 35.8% compared to a drilled Miocene limestone unconformity. This means that the Gulf of Cádiz reflector has a velocity and/or density contrast similar to the peridotite at the Gorringe Bank. However, considering the depth at which it is found (between 2.0 and 4.0 km) and the available geological information, it seems unlikely that the estimated shortening from the Oligocene to present is sufficient to emplace pieces of mantle material at these shallow levels. Therefore, and despite the similarity in its reflection coefficient with the peridotites of the Gorringe Bank, our preferred interpretation is that the upper crustal Gulf of Cádiz reflector represents the seismic response of high-density intracrustal magmatic intrusions that may partially contribute to the Gulf of Cádiz Gravity High.

First-principles study on the structural, elastic and electronic properties of Ti4N3 and Ti6N5 under high pressure

NASA Astrophysics Data System (ADS)

Yang, Ruike; Chai, Bao; Zhu, Chuanshuai; Wei, Qun; Du, Zheng

2017-12-01

The structural, elastic and electronic properties of Ti4N3 and Ti6N5 have been systematically studied by first-principles calculations based on density functional theory (DFT) with generalized gradient approximation (GGA) and local density approximation (LDA). Basic physical properties for Ti4N3 and Ti6N5, such as the lattice constants, the bulk modulus, shear modulus, and elastic constants are calculated. The results show that Ti4N3 and Ti6N5 are mechanically stable under ambient pressure. The phonon dispersion spectra are researched throughout the Brillouin zone via the linear response approach as implemented in the CASTEP code, which indicate the optimized structures are stable dynamically. The Young’s modulus E and Poisson’s ratios ν are also determined within the framework of the Voigt-Reuss-Hill approximation. The analyses show that Ti4N3 is more ductile than Ti6N5 at the same pressure and ductility increases as the pressure increases. Moreover, the anisotropies of the Ti4N3 and Ti6N5 are discussed by the Young’s modulus at different directions, and the results indicate that the anisotropy of the two Ti-N compounds is obvious. The total density of states (TDOS) and partial density of states (PDOS) show that the TDOS of TiN, Ti4N3 and Ti6N5 originate mainly from Ti “d” and N “p” states. The results show that Ti4N3 and Ti6N5 present semimetal character. Pressure makes the level range of DOS significantly extended, for TiN, Ti4N3 and Ti6N5. The TDOS decreases with the pressure rise, at Fermi level.

Uplifting the Stable Crust of the Colorado Plateau through Crustal Hydration and Warming

NASA Astrophysics Data System (ADS)

Porter, R. C.; Holt, W. E.

2016-12-01

The Colorado Plateau (CP) is a high ( 2 km above sea level), low-relief, orogenic plateau located within the interior of the southwestern United States that presents several outstanding geologic questions, most notably about the timing and mechanism(s) for uplift. The CP was located below sea level during the Cretaceous and was uplifted to its modern elevation with little crustal shortening, making the cause of uplift enigmatic. Numerous mechanisms have been hypothesized to explain the uplift of this stable block and include delamination, mantle heating/phase changes, mantle convection, volatile addition, and various combinations of these. In order to better understand the crustal contribution to uplift, we utilize data from the EarthScope Transportable Array network to image the CP lithosphere and inform thermodynamic models of CP lower crustal composition. Rayleigh wave phase velocities calculated using ambient noise tomography and surface wave gradiometry were inverted for shear velocity resulting in a high-resolution velocity model of the CP crust and upper mantle. In order to provide greater context to these results, the thermodynamic modeling code Perple_X was utilized to forward model crustal densities, seismic velocities, and water content based on psuedosections calculated using published major element chemistry. Our seismic and modeling results show that uplift of the plateau is partially driven by hydration and extension of the lower crust, both of which reduce its density. Hydration of the CP crust likely occurred due to dewatering of the Farallon slab during flat-slab subduction and reduced lower crustal density by 70 kg/m3. Warming and extension further reduced the lower crustal density by 90 kg/m3 at the CP margins. Though these processes played a role in the uplift of the CP, additional mechanisms, likely due to mantle processes, are required to fully explain its high elevation. Additionally, hydration and subsequent dehydration may play an important role in the recent encroachment of deformation and volcanism into the interior of the CP.

Measurements of neutron capture cross sections on 70Zn at 0.96 and 1.69 MeV

NASA Astrophysics Data System (ADS)

Punte, L. R. M.; Lalremruata, B.; Otuka, N.; Suryanarayana, S. V.; Iwamoto, Y.; Pachuau, Rebecca; Satheesh, B.; Thanga, H. H.; Danu, L. S.; Desai, V. V.; Hlondo, L. R.; Kailas, S.; Ganesan, S.; Nayak, B. K.; Saxena, A.

2017-02-01

The cross sections of the 70Zn(n ,γ )Zn71m (T1 /2=3.96 ±0.05 -h ) reaction have been measured relative to the 197Au(n ,γ )198Au cross sections at 0.96 and 1.69 MeV using a 7Li(p ,n )7Be neutron source and activation technique. The cross section of this reaction has been measured for the first time in the MeV region. The new experimental cross sections have been compared with the theoretical prediction by talys-1.6 with various level-density models and γ -ray strength functions as well as the tendl-2015 library. The talys-1.6 calculation with the generalized superfluid level-density model and Kopecky-Uhl generalized Lorentzian γ -ray strength function predicted the new experimental cross sections at both incident energies. The 70Zn(n ,γ ) g+m 71Zn total capture cross sections have also been derived by applying the evaluated isomeric ratios in the tendl-2015 library to the measured partial capture cross sections. The spectrum averaged total capture cross sections derived in the present paper agree well with the jendl-4.0 library at 0.96 MeV, whereas it lies between the tendl-2015 and the jendl-4.0 libraries at 1.69 MeV.

Correlations Between the Cosmic X-Ray and Microwave Backgrounds: Constraints on a Cosmological Constant

NASA Technical Reports Server (NTRS)

Boughn, S. P.; Crittenden, R. G.; Turok, N. G.

1998-01-01

In universes with significant curvature or cosmological constant, cosmic microwave background (CMB) anisotropies are created very recently via the Rees-Sciama or integrated Sachs-Wolfe effects. This causes the CMB anisotropies to become partially correlated with the local matter density (z less than 4). We examine the prospects of using the hard (2- 10 keV) X-ray background as a probe of the local density and the measured correlation between the HEAO1 A2 X-ray survey and the 4-year COBE-DMR map to obtain a constraint on the cosmological constant. The 95% confidence level upper limit on the cosmological constant is OMega(sub Lambda) less than or equal to 0.5, assuming that the observed fluctuations in the X-ray map result entirely from large scale structure. (This would also imply that the X-rays trace matter with a bias factor of b(sub x) approx. = 5.6 Omega(sub m, sup 0.53)). This bound is weakened considerably if a large portion of the X-ray fluctuations arise from Poisson noise from unresolved sources. For example, if one assumes that the X-ray bias is b(sub x) = 2, then the 95% confidence level upper limit is weaker, Omega(sub Lambda) less than or equal to 0.7. More stringent limits should be attainable with data from the next generation of CMB and X-ray background maps.

Impaired calcium sensing distinguishes primary hyperparathyroidism (PHPT) patients with low bone mineral density.

PubMed

Weber, Thomas J; Koh, James; Thomas, Samantha M; Hogue, Joyce A; Scheri, Randall P; Roman, Sanziana A; Sosa, Julie A

2017-09-01

A subset of PHPT patients exhibit a more severe disease phenotype characterized by bone loss, fractures, recurrent nephrolithiasis, and other dysfunctions, but the underlying reasons for this disparity in clinical presentation remain unknown. We sought to identify new mechanistic indices that could inform more personalized management of PHPT. Pre-, peri-, and postoperative data and demographic, clinical, and pathological information from patients undergoing parathyroidectomy for PHPT were collected. Univariate and partial Spearman correlation was used to estimate the association of parathyroid tumor calcium sensing capacity with select variables. An unselected series of 237 patients aged >18years and undergoing parathyroidectomy for PHPT were enrolled. Calcium sensing capacity, expressed as the concentration required for half-maximal biochemical response (EC50), was evaluated in parathyroid tumors from an unselected series of 74 patients and assessed for association with clinical parameters. The hypothesis was that greater disease severity would be associated with attenuated calcium sensitivity and biochemically autonomous parathyroid tumor behavior. Parathyroid tumors segregated into two distinct groups of calcium responsiveness (EC50<3.0 and ≥3.0mM). The low EC50 group (n=27) demonstrated a mean calcium EC50 value of 2.49mM [95% confidence interval (CI): 2.43-2.54mM], consistent with reference normal activity. In contrast, the high EC50 group (n=47) displayed attenuated calcium sensitivity with a mean EC50 value of 3.48mM [95% CI: 3.41-3.55mM]. Retrospective analysis of the clinical registry data suggested that high calcium EC50 patients presented with a more significant preoperative bone mineral density (BMD) deficit with a t-score of -2.7, (95% CI: -3.4 to -1.9) versus 0.9, (95% CI: -2.1 to -0.4) in low EC50 patients (p<0.001). After adjusting for gender, age, BMI, 25 OH vitamin D level and preoperative iPTH, lowest t-score and calcium EC50 were inversely correlated, with a partial Spearman correlation coefficient of -0.35 (p=0.02). Impaired calcium sensing in parathyroid tumors is selectively observed in a subset of patients with more severe bone mineral density deficit. Assessment of parathyroid tumor biochemical behavior may be a useful predictor of disease severity as measured by bone mineral density in patients with PHPT. Copyright © 2017 Elsevier Inc. All rights reserved.

Arrestin-rhodopsin binding stoichiometry in isolated rod outer segment membranes depends on the percentage of activated receptors.

PubMed

Sommer, Martha E; Hofmann, Klaus Peter; Heck, Martin

2011-03-04

In the rod cell of the retina, arrestin is responsible for blocking signaling of the G-protein-coupled receptor rhodopsin. The general visual signal transduction model implies that arrestin must be able to interact with a single light-activated, phosphorylated rhodopsin molecule (Rho*P), as would be generated at physiologically relevant low light levels. However, the elongated bi-lobed structure of arrestin suggests that it might be able to accommodate two rhodopsin molecules. In this study, we directly addressed the question of binding stoichiometry by quantifying arrestin binding to Rho*P in isolated rod outer segment membranes. We manipulated the "photoactivation density," i.e. the percentage of active receptors in the membrane, with the use of a light flash or by partially regenerating membranes containing phosphorylated opsin with 11-cis-retinal. Curiously, we found that the apparent arrestin-Rho*P binding stoichiometry was linearly dependent on the photoactivation density, with one-to-one binding at low photoactivation density and one-to-two binding at high photoactivation density. We also observed that, irrespective of the photoactivation density, a single arrestin molecule was able to stabilize the active metarhodopsin II conformation of only a single Rho*P. We hypothesize that, although arrestin requires at least a single Rho*P to bind the membrane, a single arrestin can actually interact with a pair of receptors. The ability of arrestin to interact with heterogeneous receptor pairs composed of two different photo-intermediate states would be well suited to the rod cell, which functions at low light intensity but is routinely exposed to several orders of magnitude more light.

Comparative study of initial stages of copper immersion deposition on bulk and porous silicon

NASA Astrophysics Data System (ADS)

Bandarenka, Hanna; Prischepa, Sergey L.; Fittipaldi, Rosalba; Vecchione, Antonio; Nenzi, Paolo; Balucani, Marco; Bondarenko, Vitaly

2013-02-01

Initial stages of Cu immersion deposition in the presence of hydrofluoric acid on bulk and porous silicon were studied. Cu was found to deposit both on bulk and porous silicon as a layer of nanoparticles which grew according to the Volmer-Weber mechanism. It was revealed that at the initial stages of immersion deposition, Cu nanoparticles consisted of crystals with a maximum size of 10 nm and inherited the orientation of the original silicon substrate. Deposited Cu nanoparticles were found to be partially oxidized to Cu2O while CuO was not detected for all samples. In contrast to porous silicon, the crystal orientation of the original silicon substrate significantly affected the sizes, density, and oxidation level of Cu nanoparticles deposited on bulk silicon.

SWSA 6 interim corrective measures environmental monitoring: FY 1991 results

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

Clapp, R.B.; Marshall, D.S.

1992-06-01

In 1988, interim corrective measures (ICMs) were implemented at Solid Waste Storage Area (SWSA) 6 at Oak Ridge National Laboratory. The SWSA 6 site was regulated under the Resource Conservation and Recovery Act (RCRA). The ICMs consist of eight large high-density polyethylene sheets placed as temporary caps to cover trenches known to contain RCRA-regulated materials. Environmental monitoring for FY 1991 consisted of collecting water levels at 13 groundwater wells outside the capped areas and 44 wells in or near the capped areas in order to identify any significant loss of hydrologic isolation of the wastes. Past annual reports show thatmore » the caps are only partially effective in keeping the waste trenches dry and that many trenches consistently or intermittently contain water.« less

SWSA 6 interim corrective measures environmental monitoring: FY 1991 results. Environmental Restoration Program

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

Clapp, R.B.; Marshall, D.S.

1992-06-01

In 1988, interim corrective measures (ICMs) were implemented at Solid Waste Storage Area (SWSA) 6 at Oak Ridge National Laboratory. The SWSA 6 site was regulated under the Resource Conservation and Recovery Act (RCRA). The ICMs consist of eight large high-density polyethylene sheets placed as temporary caps to cover trenches known to contain RCRA-regulated materials. Environmental monitoring for FY 1991 consisted of collecting water levels at 13 groundwater wells outside the capped areas and 44 wells in or near the capped areas in order to identify any significant loss of hydrologic isolation of the wastes. Past annual reports show thatmore » the caps are only partially effective in keeping the waste trenches dry and that many trenches consistently or intermittently contain water.« less

Effect of lipid emulsions on the plasma lecithin: cholesterol acyltransfer in guinea pigs.

PubMed

Drevon, C A; Norum, K R

1975-01-01

Addition of triglyceride/phospholipid emulsion to adult guinea pig plasma more than doubled the cholesteryl ester (CE) production. Plasma from newborn guinea pigs was stimulated to a lower degree. The increase in CE production was dependant on the type and amount of phospholipids in the lipid emulsions. Egg phospholipids stimulated the cholesterol esterification while partially hydrogenated soy phospholipids (with high content of saturated fatty acids) inhibited the reaction. The stimulation of CE formation was probably due to transfer of phosphatidyl choline (PC) from the emulsion to the high density lipoproteins since the stimulation was: (a) dependant on a preincubation time, (b) less pronounced in newborn animals with high plasma PC levels, and (c) detected in plasma fractions from which the lipid emulsion had been removed.

Efficacy, but not antibody titer or affinity, of a heroin hapten conjugate vaccine correlates with increasing hapten densities on tetanus toxoid, but not on CRM197 carriers.

PubMed

Jalah, Rashmi; Torres, Oscar B; Mayorov, Alexander V; Li, Fuying; Antoline, Joshua F G; Jacobson, Arthur E; Rice, Kenner C; Deschamps, Jeffrey R; Beck, Zoltan; Alving, Carl R; Matyas, Gary R

2015-06-17

Vaccines against drugs of abuse have induced antibodies in animals that blocked the biological effects of the drug by sequestering the drug in the blood and preventing it from crossing the blood-brain barrier. Drugs of abuse are too small to induce antibodies and, therefore, require conjugation of drug hapten analogs to a carrier protein. The efficacy of these conjugate vaccines depends on several factors including hapten design, coupling strategy, hapten density, carrier protein selection, and vaccine adjuvant. Previously, we have shown that 1 (MorHap), a heroin/morphine hapten, conjugated to tetanus toxoid (TT) and mixed with liposomes containing monophosphoryl lipid A [L(MPLA)] as adjuvant, partially blocked the antinociceptive effects of heroin in mice. Herein, we extended those findings, demonstrating greatly improved vaccine induced antinociceptive effects up to 3% mean maximal potential effect (%MPE). This was obtained by evaluating the effects of vaccine efficacy of hapten 1 vaccine conjugates with varying hapten densities using two different commonly used carrier proteins, TT and cross-reactive material 197 (CRM197). Immunization of mice with these conjugates mixed with L(MPLA) induced very high anti-1 IgG peak levels of 400-1500 μg/mL that bound to both heroin and its metabolites, 6-acetylmorphine and morphine. Except for the lowest hapten density for each carrier, the antibody titers and affinity were independent of hapten density. The TT carrier based vaccines induced long-lived inhibition of heroin-induced antinociception that correlated with increasing hapten density. The best formulation contained TT with the highest hapten density of ≥30 haptens/TT molecule and induced %MPE of approximately 3% after heroin challenge. In contrast, the best formulation using CRM197 was with intermediate 1 densities (10-15 haptens/CRM197 molecule), but the %MPE was approximately 13%. In addition, the chemical synthesis of 1, the optimization of the conjugation method, and the methods for the accurate quantification of hapten density are described.

Numerical modeling of a sub Plinian eruption at La Soufrière de Guadeloupe: implications for pyroclastic density currents hazard assessment.

NASA Astrophysics Data System (ADS)

Esposti Ongaro, Tomaso; Neri, Augusto; Komorowski, Jean-Christophe

2013-04-01

We present three-dimensional numerical simulations of a sub-Plinian eruptive scenario at La Soufrière de Guadeloupe, aimed at assessing the capability of pyroclastic density currents to reach the inhabited regions on the volcano slopes, in case of the future resumption of the explosive activity. The selected eruptive scenario is similar to that hypothesized for the 1530 a.D. eruption, but several eruptive conditions have been analyzed to account for different behaviours of the eruptive column and percentages of collapse. Numerical results describe, in 3D and in time, the formation, instability and partial collapse of the eruptive column, and the simultaneous formation of a convective plume and several branched pyroclastic density currents. The proximal volcano morphology, characterized by the presence of ancient caldera rims and the remnants of the old edifice, controls the areal distribution of the collapsed material and the paths of channelized flows along the incised topography. The analysis of the 3D runs suggests that partial collapse scenarios produce steeply stratified pyroclastic density currents, which are strongly controlled by the topography and whose propagation is likely driven by the dynamics of the dense, basal layer. Although vertical grid size still does not allow the resolution of the dynamics of such concentrated flows, preliminary georeferenced maps of pyroclastic density currents' hazardous actions (temperature and dynamic pressure) provide interesting and useful information which can serve as a basis for elaborating a quantitative framework for the assessment of their impact on vulnerable infrastructures, networks, and population.

Management of lactating sows during heat stress: effects of water drip, snout coolers, floor type and a high energy-density diet.

PubMed

McGlone, J J; Stansbury, W F; Tribble, L F

1988-04-01

Two experiments using 120 sows were conducted to determine the effects during heat stress of two floor types, snout coolers or a water drip system, and a high energy-density diet. During both studies, air temperature was maintained at or above 29 degrees C. Floor types included partially slotted concrete and plastic-coated, expanded metal. In Exp. 1, in addition to floor-type treatments, snout coolers were on or off and the water drip was on for 3 min each 10 min or off. Snout coolers increased (P less than .05) sow feed intake and decreased (P less than .05) sow lactation weight loss. Water drip increased (P less than .002) sow feed intake and reduced lactation weight loss. The drip X floor-type interaction was significant for most measures of piglet performance. Drip was beneficial for piglet weights when piglets were on plastic, whereas drip was detrimental to piglet performance while they were housed on concrete. In Exp. 2, two floor types, drip or no-drip and a high energy-density diet or control diet were examined during heat stress. The high energy-density diet reduced (P less than .01) sow feed intake but provided no measurable increase in piglet performance during heat stress. We conclude that water drip is an effective cooling technique for heat-stressed sows, especially when floors are plastic. Snout coolers, partial concrete slots and high energy-density diets provided only minor benefits to heat-stressed sows and were not of benefit to piglets nursing heat-stressed sows.

First principles analysis of the CDW instability of single-layer 1T-TiSe2 and its evolution with charge carrier density

NASA Astrophysics Data System (ADS)

Guster, Bogdan; Canadell, Enric; Pruneda, Miguel; Ordejón, Pablo

2018-04-01

We present a density functional theory study of the electronic structure of single-layer TiSe2, and focus on the charge density wave (CDW) instability present on this 2D material. We explain the 2× 2 periodicity of the CDW from the phonon band structure of the undistorted crystal, which is unstable under one of the phonon modes at the M point. This can be understood in terms of a partial band gap opening at the Fermi level, which we describe on the basis of the symmetry of the involved crystal orbitals, leading to an energy gain upon the displacement of the atoms following the phonon mode in a 2  ×  1 structure. Furthermore, the combination of the corresponding phonons for the three inequivalent M points of the Brillouin zone leads to the 2  ×  2 distortion characteristic of the CDW state. This leads to a further opening of a full gap, which reduces the energy of the 2  ×  2 structure compared to the 2  ×  1 one of a single M point phonon, and makes the CDW structure the most stable one. We also analyze the effect of charge injection into the layer on the structural instability. We predict that the 2  ×  2 structure only survives for a certain range of doping levels, both for electrons and for holes, as doping reduces the energy gain due to the gap opening. We predict the transition from the commensurate 2  ×  2 distortion to an incommensurate one with increasing wavelength upon increasing the doping level, followed by the appearance of the undistorted 1  ×  1 structure for larger carrier concentrations.

Social capital, ethnic density and mental health among ethnic minority people in England: a mixed-methods study.

PubMed

Becares, Laia; Nazroo, James

2013-01-01

Ethnic minority people have been suggested to be healthier when living in areas with a higher concentration of people from their own ethnic group, a so-called ethnic density effect. Explanations behind the ethnic density effect propose that positive health outcomes are partially attributed to the protective and buffering effects of increased social capital on health. In fact, a parallel literature has reported increased levels of social capital in areas of greater ethnic residential diversity, but to date, no study in England has explored whether increased social capital mediates the relationship between protective effects attributed to the residential concentration of ethnic minority groups and health. We employ a mixed-methods approach to examine the association between ethnicity, social capital and mental health. We analyse geocoded data from the 2004 Health Survey for England to examine the association between (1) ethnic residential concentration and health; (2) ethnic residential concentration and social capital; (3) social capital and health; and (4) the mediating effect of social capital on the association between the residential concentration of ethnic groups and health. To further add to our understanding of the processes involved, data from a qualitative study of quality older ethnic minority people were be used to examine accounts of the significance of place of residence to quality of life. The association between ethnic density and social capital varies depending on the level of measurement of social capital and differed across ethnic minority groups. Social capital was not found to mediate the association between ethnic density and health. Structural differences in the characteristics of the neighbourhoods where different ethnic groups reside are reflected in the accounts of their daily experiences, and we observed different narratives of neighbourhood experiences between Indian and Caribbean respondents. The use of mixed methods provides an important contribution to the study of ethnic minority people's experience of their neighbourhood, as this approach has allowed us to gain important insights that cannot be inferred from quantitative or qualitative data alone.

Observation of Phase-Filling Singularities in the Optical Dielectric Function of Highly Doped n-Type Ge.

PubMed

Xu, Chi; Fernando, Nalin S; Zollner, Stefan; Kouvetakis, John; Menéndez, José

2017-06-30

Phase-filling singularities in the optical response function of highly doped (>10^{19}  cm^{-3}) germanium are theoretically predicted and experimentally confirmed using spectroscopic ellipsometry. Contrary to direct-gap semiconductors, which display the well-known Burstein-Moss phenomenology upon doping, the critical point in the joint density of electronic states associated with the partially filled conduction band in n-Ge corresponds to the so-called E_{1} and E_{1}+Δ_{1} transitions, which are two-dimensional in character. As a result of this reduced dimensionality, there is no edge shift induced by Pauli blocking. Instead, one observes the "original" critical point (shifted only by band gap renormalization) and an additional feature associated with the level occupation discontinuity at the Fermi level. The experimental observation of this feature is made possible by the recent development of low-temperature, in situ doping techniques that allow the fabrication of highly doped films with exceptionally flat doping profiles.

The structural, electronic and optical properties of Nd doped ZnO using first-principles calculations

NASA Astrophysics Data System (ADS)

Wen, Jun-Qing; Zhang, Jian-Min; Chen, Guo-Xiang; Wu, Hua; Yang, Xu

2018-04-01

The density functional theory calculations using general gradient approximation (GGA) applying Perdew-Burke-Ernzerhof (PBE) as correlation functional have been systematically performed to research the formation energy, the electronic structures, band structures, total and partial DOS, and optical properties of Nd doping ZnO with the content from 6.25% to 12.5%. The formation energies are negative for both models, which show that two structures are energetically stable. Nd doping ZnO crystal is found to be a direct band gap semiconductor and Fermi level shifts upward into conduction band, which show the properties of n-type semiconductor. Band structures are more compact after Nd doping ZnO, implying that Nd doping induces the strong interaction between different atoms. Nd doping ZnO crystal presents occupied states at near Fermi level, which mainly comes from the Nd 4f orbital. The calculated optical properties imply that Nd doping causes a red-shift of absorption peaks, and enhances the absorption of the visible light.

Vertical distribution of vibrational energy of molecular nitrogen in a stable auroral red arc and its effect on ionospheric electron densities. Ph.D. Thesis - Catholic Univ. of Am.

NASA Technical Reports Server (NTRS)

Newton, G. P.

1973-01-01

Previous solutions of the problem of the distribution of vibrationally excited molecular nitrogen in the thermosphere have either assumed a Boltzmann distribution and considered diffusion as one of the loss processes or solved for the energy level populations and neglected diffusion. Both of the previous approaches are combined by solving the time dependent continuity equations, including the diffusion process, for the first six energy levels of molecular nitrogen for conditions in the thermosphere corresponding to a stable auroral red arc. The primary source of molecular nitrogen excitation was subexcitation, and inelastic collisions between thermal electrons and molecular nitrogen. The reaction rates for this process were calculated from published cross section calculations. The loss processes for vibrational energy were electron and atomic oxygen quenching and vibrational energy exchange. The coupled sets of nonlinear, partial differential equations were solved numerically by employing finite difference equations.

Plasma membrane cholesterol level and agonist-induced internalization of δ-opioid receptors; colocalization study with intracellular membrane markers of Rab family.

PubMed

Brejchova, Jana; Vosahlikova, Miroslava; Roubalova, Lenka; Parenti, Marco; Mauri, Mario; Chernyavskiy, Oleksandr; Svoboda, Petr

2016-08-01

Decrease of cholesterol level in plasma membrane of living HEK293 cells transiently expressing FLAG-δ-OR by β-cyclodextrin (β-CDX) resulted in a slight internalization of δ-OR. Massive internalization of δ-OR induced by specific agonist DADLE was diminished in cholesterol-depleted cells. These results suggest that agonist-induced internalization of δ-OR, which has been traditionally attributed exclusively to clathrin-mediated pathway, proceeds at least partially via membrane domains. Identification of internalized pools of FLAG-δ-OR by colocalization studies with proteins of Rab family indicated the decreased presence of receptors in early endosomes (Rab5), late endosomes and lysosomes (Rab7) and fast recycling vesicles (Rab4). Slow type of recycling (Rab11) was unchanged by cholesterol depletion. As expected, agonist-induced internalization of oxytocin receptors was totally suppressed in β-CDX-treated cells. Determination of average fluorescence lifetime of TMA-DPH, the polar derivative of hydrophobic membrane probe diphenylhexatriene, in live cells by FLIM indicated a significant alteration of the overall PM structure which may be interpreted as an increased "water-accessible space" within PM area. Data obtained by studies of HEK293 cells transiently expressing FLAG-δ-OR by "antibody feeding" method were extended by analysis of the effect of cholesterol depletion on distribution of FLAG-δ-OR in sucrose density gradients prepared from HEK293 cells stably expressing FLAG-δ-OR. Major part of FLAG-δ-OR was co-localized with plasma membrane marker Na,K-ATPase and β-CDX treatment resulted in shift of PM fragments containing both FLAG-δ-OR and Na,K-ATPase to higher density. Thus, the decrease in content of the major lipid constituent of PM resulted in increased density of resulting PM fragments.

Four in vivo g-ratio-weighted imaging methods: Comparability and repeatability at the group level.

PubMed

Ellerbrock, Isabel; Mohammadi, Siawoosh

2018-01-01

A recent method, denoted in vivo g-ratio-weighted imaging, has related the microscopic g-ratio, only accessible by ex vivo histology, to noninvasive MRI markers for the fiber volume fraction (FVF) and myelin volume fraction (MVF). Different MRI markers have been proposed for g-ratio weighted imaging, leaving open the question which combination of imaging markers is optimal. To address this question, the repeatability and comparability of four g-ratio methods based on different combinations of, respectively, two imaging markers for FVF (tract-fiber density, TFD, and neurite orientation dispersion and density imaging, NODDI) and two imaging markers for MVF (magnetization transfer saturation rate, MT, and, from proton density maps, macromolecular tissue volume, MTV) were tested in a scan-rescan experiment in two groups. Moreover, it was tested how the repeatability and comparability were affected by two key processing steps, namely the masking of unreliable voxels (e.g., due to partial volume effects) at the group level and the calibration value used to link MRI markers to MVF (and FVF). Our data showed that repeatability and comparability depend largely on the marker for the FVF (NODDI outperformed TFD), and that they were improved by masking. Overall, the g-ratio method based on NODDI and MT showed the highest repeatability (90%) and lowest variability between groups (3.5%). Finally, our results indicate that the calibration procedure is crucial, for example, calibration to a lower g-ratio value (g = 0.6) than the commonly used one (g = 0.7) can change not only repeatability and comparability but also the reported dependency on the FVF imaging marker. Hum Brain Mapp 39:24-41, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Lipid profile lowering effect of Soypro fermented with lactic acid bacteria isolated from Kimchi in high-fat diet-induced obese rats.

PubMed

Kim, Na-Hyung; Moon, Phil-Dong; Kim, Su-Jin; Choi, In-Young; An, Hyo-Jin; Myung, Noh-Yil; Jeong, Hyun-Ja; Um, Jae-Young; Hong, Seung-Heon; Kim, Hyung-Min

2008-01-01

Lactic acid bacteria are known to exert various physiologic functions in humans. In the current study, we investigated the effects of Soypro, a new soymilk fermented with lactic acid bacteria, like Leuconostoc kimchii, Leuconostoc citreum, and Lactobacillus plantarum, isolated from Kimchi, on adipocyte differentiation in preadipocyte 3T3-L1 cell lines and weight gain or the plasma lipid profile in Sprague-Dawley rats. Adipocyte 3T3-L1 cells treated with Soypro (10 microg/ml) significantly reduced the contents of cellular triglyceride and inhibited cell differentiation by Oil red O staining. Treatment with Soypro (10 microg/ml) for an additional two days in adipocytes inhibited the expression of peroxisome proliferator-activated receptor-gamma2 and CCAAT/enhancer binding protein-alpha, transcription factors of adipocyte differentiation. Based on these in vitro studies, we examined the anti-obesity effect of Soypro in rats for six weeks. Soypro had no significant effect on high-fat diet-induced increases in body weight, food intake, or feed gain ratio. However, the administration of Soypro significantly reduced the concentration of the plasma low density lipoprotein cholesterol. Changes in the plasma levels of total cholesterol and glucose were inclined to decrease in Soypro administrated groups compared with saline treated group. Triglyceride and high density lipoprotein cholesterol values in Soypro fed groups were similar compared to those of saline fed groups. Although further research is needed, these findings suggest that Soypro decreased the levels of low density lipoprotein cholesterol in high-fat diet-induced obesity and might partially inhibit the adipocyte differentiation through the suppression of a transcription factors peroxisome proliferator-activated receptor-gamma2 and CCAAT/enhancer binding protein-alpha.

Experimental evaluation of analyte excitation mechanisms in the inductively coupled plasma

NASA Astrophysics Data System (ADS)

Lehn, Scott A.; Hieftje, Gary M.

2003-10-01

The inductively coupled plasma (ICP) is a justifiably popular source for atomic emission spectrometry. However, despite its popularity, the ICP is still only partially understood. Even the mechanisms of analyte excitation remain unclear; some energy levels are quite clearly populated by charge transfer while others might be populated by electron-ion recombination, by electron impact, or by Penning processes. Distinguishing among these alternatives is possible by means of a steady-state kinetics approach that examines correlations between the emission of a selected atom, ion, or level and the local number densities of species assumed to produce the excitation. In an earlier investigation, strong correlations were found between either calcium atom or ion emission and selected combinations of calcium atom or ion number densities and electron number densities in the plasma. However, all radially resolved data employed in the earlier study were produced from Abel inversion and from measurements that were crude by today's standards. Now, by means of tomographic imaging, laser-saturated atomic fluorescence, and Thomson and Rayleigh scattering, it is possible to measure the required radially resolved data without Abel inversion and with far greater fidelity. The correlations previously studied for calcium have been investigated with these more reliable data. Ion-electron recombination, either radiative or with argon as a third body, was determined to be the most likely excitation mechanism for calcium atom, while electron impact appeared to be the most important process to produce excite-state calcium ions. These results were consistent with the previous study. However, the present study suggests that collisional deactivation, rather than radiative decay, is the most likely mode of returning both calcium atoms and ions to the ground state.

Nonparametric model validations for hidden Markov models with applications in financial econometrics

PubMed Central

Zhao, Zhibiao

2011-01-01

We address the nonparametric model validation problem for hidden Markov models with partially observable variables and hidden states. We achieve this goal by constructing a nonparametric simultaneous confidence envelope for transition density function of the observable variables and checking whether the parametric density estimate is contained within such an envelope. Our specification test procedure is motivated by a functional connection between the transition density of the observable variables and the Markov transition kernel of the hidden states. Our approach is applicable for continuous time diffusion models, stochastic volatility models, nonlinear time series models, and models with market microstructure noise. PMID:21750601

Probabilistic Density Function Method for Stochastic ODEs of Power Systems with Uncertain Power Input

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

Wang, Peng; Barajas-Solano, David A.; Constantinescu, Emil

Wind and solar power generators are commonly described by a system of stochastic ordinary differential equations (SODEs) where random input parameters represent uncertainty in wind and solar energy. The existing methods for SODEs are mostly limited to delta-correlated random parameters (white noise). Here we use the Probability Density Function (PDF) method for deriving a closed-form deterministic partial differential equation (PDE) for the joint probability density function of the SODEs describing a power generator with time-correlated power input. The resulting PDE is solved numerically. A good agreement with Monte Carlo Simulations shows accuracy of the PDF method.

Computational evaluation of sub-nanometer cluster activity of singly exposed copper atom with various coordinative environment in catalytic CO2 transformation

NASA Astrophysics Data System (ADS)

Shanmugam, Ramasamy; Thamaraichelvan, Arunachalam; Ganesan, Tharumeya Kuppusamy; Viswanathan, Balasubramanian

2017-02-01

Metal cluster, at sub-nanometer level has a unique property in the activation of small molecules, in contrast to that of bulk surface. In the present work, singly exposed active site of copper metal cluster at sub-nanometer level was designed to arrive at the energy minimised configurations, binding energy, electrostatic potential map, frontier molecular orbitals and partial density of states. The ab initio molecular dynamics was carried out to probe the catalytic nature of the cluster. Further, the stability of the metal cluster and its catalytic activity in the electrochemical reduction of CO2 to CO were evaluated by means of computational hydrogen electrode via calculation of the free energy profile using DFT/B3LYP level of theory in vacuum. The activity of the cluster is ascertained from the fact that the copper atom, present in a two coordinative environment, performs a more selective conversion of CO2 to CO at an applied potential of -0.35 V which is comparatively lower than that of higher coordinative sites. The present study helps to design any sub-nano level metal catalyst for electrochemical reduction of CO2 to various value added chemicals.

Interface Energy Alignment of Atomic-Layer-Deposited VOx on Pentacene: an in Situ Photoelectron Spectroscopy Investigation.

PubMed

Zhao, Ran; Gao, Yuanhong; Guo, Zheng; Su, Yantao; Wang, Xinwei

2017-01-18

Ultrathin atomic-layer-deposited (ALD) vanadium oxide (VO x ) interlayer has recently been demonstrated for remarkably reducing the contact resistance in organic electronic devices (Adv. Funct. Mater. 2016, 26, 4456). Herein, we present an in situ photoelectron spectroscopy investigation (including X-ray and ultraviolet photoelectron spectroscopies) of ALD VO x grown on pentacene to understand the role of the ALD VO x interlayer for the improved contact resistance. The in situ photoelectron spectroscopy characterizations allow us to monitor the ALD growth process of VO x and trace the evolutions of the work function, pentacene HOMO level, and VO x defect states during the growth. The initial VO x growth is found to be partially delayed on pentacene in the first ∼20 ALD cycles. The underneath pentacene layer is largely intact after ALD. The ALD VO x is found to contain a high density of defect states starting from 0.67 eV below the Fermi level, and the energy level of these defect states is in excellent alignment with the HOMO level of pentacene, which therefore allows these VO x defect states to provide an efficient hole-injection pathway at the contact interface.

Simulations of Hall reconnection in partially ionized plasmas

NASA Astrophysics Data System (ADS)

Innocenti, Maria Elena; Jiang, Wei; Lapenta, Giovanni

2017-04-01

Magnetic reconnection occurs in the Hall, partially ionized regime in environments as diverse as molecular clouds, protostellar disks and regions of the solar chromosphere. While much is known about Hall reconnection in fully ionized plasmas, Hall reconnection in partially ionized plasmas is, in comparison, still relatively unexplored. This notwithstanding the fact that partial ionization is expected to affect fundamental processes in reconnection such as the transition from the slow, fluid to the fast, kinetic regime, the value of the reconnection rate and the dimensions of the diffusion regions [Malyshkin and Zweibel 2011 , Zweibel et al. 2011]. We present here the first, to our knowledge, fully kinetic simulations of Hall reconnection in partially ionized plasmas. The interaction of electrons and ions with the neutral background is realistically modelled via a Monte Carlo plug-in coded into the semi-implicit, fully kinetic code iPic3D [Markidis 2010]. We simulate a plasma with parameters compatible with the MRX experiments illustrated in Zweibel et al. 2011 and Lawrence et al. 2013, to be able to compare our simulation results with actual experiments. The gas and ion temperature is T=3 eV, the ion to electron temperature ratio is Tr=0.44, ion and electron thermal velocities are calculated accordingly resorting to a reduced mass ratio and a reduced value of the speed of light to reduce the computational costs of the simulations. The initial density of the plasma is set at n= 1.1 1014 cm-3 and is then left free to change during the simulation as a result of gas-plasma interaction. A set of simulations with initial ionisation percentage IP= 0.01, 0.1, 0.2, 0.6 is presented and compared with a reference simulation where no background gas is present (full ionization). In this first set of simulations, we assume to be able to externally control the initial relative densities of gas and plasma. Within this parameter range, the ion but not the electron population is heavily affected by collisions with the neutrals. In line with experimental results, we observe reduction of the reconnection rate and no variation of the half-thickness of the ion diffusion region with decreasing IP (increasing gas density). Contrarily to the experiments, we can confidently state that these effects are not influenced by boundary constraints. We then provide an explanation for the behaviour observed.

Evaluation of Lipid Profile Changes in Pediatric Patients with Acute Mononucleosis

PubMed Central

2017-01-01

Background Acute Epstein-Barr virus (EBV) infection could lead to atherogenic lipid profile changes in adults; while there is no evidence about the children with Infectious mononucleosis (IM). The aim of this study was to evaluate the lipid profile of the children in acute phase of mononucleosis and two months after the recovery. Materials and Methods From 2010 through 2012, 36 children with IM aged 1-10 years were enrolled in a prospective cross-sectional study. Fasting serum total cholesterol, high density lipoprotein (HDL), low density lipoprotein (LDL), and triglyceride level were measured during acute phase of the disease and after 2 months of the recovery. Results From 36 patients enrolled, 25 (69.4%) cases were male and the mean age of the patients was 4.1 ± 2.0 years. The mean of the total cholesterol level in the acute phase and 2 months after the recovery were149.5 ± 35.3 mg/dL and 145.7±30.6, respectively (P = 0.38). However, the serum level of HDL cholesterol in patients after 2 months of recovery was significantly increased (37.9 ± 9.3 mg/dL vs. 28.5 ± 10.6 mg/dL, P <0.001). The mean value of serum LDL cholesterol was significantly reduced, two months after recovery (81.4 ± 19.5 mg/dL, vs. 92.6 ± 28.8 mg/dL, P = 0.009). Furthermore, the serum triglyceride level was significantly reduced after the recovery (108.7 ± 36.9 mg/dL) compared with the acute phase (163.8 ± 114.3 mg/dL) (P = 0.004). Conclusion EBV infection in children could change lipid profile which is partially restored 2 months after the recovery. PMID:28332346

Complete reduction of high-density UO2 to metallic U in molten Li2O-LiCl

NASA Astrophysics Data System (ADS)

Choi, Eun-Young; Lee, Jeong

2017-10-01

The large size and high density of spent fuel pellets make it difficult to use the pellets directly in electrolytic reduction (also called as oxide reduction, OR) for pyroprocessing owing to the slow diffusion of molten Li2O-LiCl salt electrolyte into the pellets. In this study, we investigated complete OR of high-density UO2 to metallic U without any remaining UO2. Only partial reductions near the surface of high-density UO2 pellets were observed under operation conditions employing fast electrolysis rate that allowed previously complete reduction of low-density UO2 pellets. Complete reduction of high-density UO2 pellets was observed at fast electrolysis rate when the pellet size was reduced. The complete reduction of high-density UO2 pellets without size reduction was achieved at slow electrolysis rate, which allowed sufficient chemical reduction of UO2 with the lithium metal generated by the cathode reaction.

Electronic structure of silver doped As2S3

NASA Astrophysics Data System (ADS)

Kaur, Veerpal; Khatta, Swati; Tripathi, S. K.; Prakash, S.

2018-04-01

We have studied the band structure, density of states and partial density of states for pure arsenic trisulfide (As2S3) and silver (Ag) doped arsenic trisulfide (As2S3) using DFT based GGA approach. It is observed that with the introduction of silver in As2S3, some extra states are observed in the gap region hence modifying the semiconducting gap in As2S3. These extra states in the gap region are due to 4d-states of silver.

Concentration dependences of the density, viscosity, and refraction index of Cu(NO3)2 · 3H2O solutions in DMSO at 298 K

NASA Astrophysics Data System (ADS)

Mamyrbekova, A. K.

2013-03-01

Physicochemical properties (density, dynamic viscosity, refraction index) of the DMSO-Cu(NO3)2 · 3H2O system are studied in the concentration range of 0.01-2 M at 298 K. The refraction index of a solution of copper(II) nitrate in dimethylsulfoxide (DMSO) is measured at 288-318 K. The excess and partial molar volumes of the solvent and dissolved substance are calculated analytically.

High spectral resolution lidar using spherical Fabry-Perot to measure aerosol and atmospheric molecular density

NASA Astrophysics Data System (ADS)

Yann, Caraty; Alain, Hauchecorne; Philippe, Keckhut; Jean-François, Mariscal; Eric, Dalmeida

2018-04-01

In theory, the HSRL method should expand the validity range of the atmospheric molecular density and temperature profiles of the Rayleigh LIDAR in the UTLS below 30 km, with an accuracy of 1 K, while suppressing the particle contribution. We tested a Spherical Fabry-Perot which achieves these performances while keeping a big flexibility in optical alignment. However, this device has some limitations (thermal drift and a possible partial depolarisation of the backscattered signal).

A stochastic-field description of finite-size spiking neural networks

PubMed Central

Longtin, André

2017-01-01

Neural network dynamics are governed by the interaction of spiking neurons. Stochastic aspects of single-neuron dynamics propagate up to the network level and shape the dynamical and informational properties of the population. Mean-field models of population activity disregard the finite-size stochastic fluctuations of network dynamics and thus offer a deterministic description of the system. Here, we derive a stochastic partial differential equation (SPDE) describing the temporal evolution of the finite-size refractory density, which represents the proportion of neurons in a given refractory state at any given time. The population activity—the density of active neurons per unit time—is easily extracted from this refractory density. The SPDE includes finite-size effects through a two-dimensional Gaussian white noise that acts both in time and along the refractory dimension. For an infinite number of neurons the standard mean-field theory is recovered. A discretization of the SPDE along its characteristic curves allows direct simulations of the activity of large but finite spiking networks; this constitutes the main advantage of our approach. Linearizing the SPDE with respect to the deterministic asynchronous state allows the theoretical investigation of finite-size activity fluctuations. In particular, analytical expressions for the power spectrum and autocorrelation of activity fluctuations are obtained. Moreover, our approach can be adapted to incorporate multiple interacting populations and quasi-renewal single-neuron dynamics. PMID:28787447

Analytical and numerical study of the transverse Kelvin-Helmholtz instability in tokamak edge plasmas

DOE PAGES

Myra, James R.; D'Ippolito, Daniel A.; Russell, David A.; ...

2016-04-11

Sheared flows perpendicular to the magnetic field can be driven by the Reynolds stress or ion pressure gradient effects and can potentially influence the stability and turbulent saturation level of edge plasma modes. On the other hand, such flows are subject to the transverse Kelvin- Helmholtz (KH) instability. Here, the linear theory of KH instabilities is first addressed with an analytic model in the asymptotic limit of long wavelengths compared with the flow scale length. The analytic model treats sheared ExB flows, ion diamagnetism (including gyro-viscous terms), density gradients and parallel currents in a slab geometry, enabling a unified summarymore » that encompasses and extends previous results. In particular, while ion diamagnetism, density gradients and parallel currents each individually reduce KH growth rates, the combined effect of density and ion pressure gradients is more complicated and partially counteracting. Secondly, the important role of realistic toroidal geometry is explored numerically using an invariant scaling analysis together with the 2DX eigenvalue code to examine KH modes in both closed and open field line regions. For a typical spherical torus magnetic geometry, it is found that KH modes are more unstable at and just outside the separatrix as a result of the distribution of magnetic shear. Lastly implications for reduced edge turbulence modeling codes are discussed.« less

Bone preserving level of osteotomy in short-stem total hip arthroplasty does not influence stress shielding dimensions - a comparing finite elements analysis.

PubMed

Burchard, Rene; Braas, Sabrina; Soost, Christian; Graw, Jan Adriaan; Schmitt, Jan

2017-08-07

The main objective of every new development in total hip arthroplasty (THA) is the longest possible survival of the implant. Periprosthetic stress shielding is a scientifically proven phenomenon which leads to inadvertent bone loss. So far, many studies have analysed whether implanting different hip stem prostheses result in significant preservation of bone stock. The aim of this preclinical study was to investigate design-depended differences of the stress shielding effect after implantation of a selection of short-stem THA-prostheses that are currently available. Based on computerised tomography (CT), a finite elements (FE) model was generated and a virtual THA was performed with different stem designs of the implant. Stems were chosen by osteotomy level at the femoral neck (collum, partial collum, trochanter sparing, trochanter harming). Analyses were performed with previously validated FE models to identify changes in the strain energy density (SED). In the trochanteric region, only the collum-type stem demonstrated a biomechanical behaviour similar to the native femur. In contrast, no difference in biomechanical behaviour was found between partial collum, trochanter harming and trochanter sparing models. All of the short stem-prostheses showed lower stress-shielding than a standard stem. Based on the results of this study, we cannot confirm that the design of current short stem THA-implants leads to a different stress shielding effect with regard to the level of osteotomy. Somehow unexpected, we found a bone stock protection in metadiaphyseal bone by simulating a more distal approach for osteotomy. Further clinical and biomechanical research including long-term results is needed to understand the influence of short-stem THA on bone remodelling and to find the optimal stem-design for a reduction of the stress shielding effect.

Simvastatin does not diminish the in vivo degeneration of decellularized aortic conduits.

PubMed

Assmann, Alexander; Horstkötter, Kim; Munakata, Hiroshi; Schiffer, Franziska; Delfs, Christofer; Zwirnmann, Kai; Barth, Mareike; Akhyari, Payam; Lichtenberg, Artur

2014-10-01

All present biological cardiovascular prostheses are prone to progressive in vivo degeneration, which can be partially impaired by decellularization. The administration of statins may provide an additional beneficial effect. We provide the first in vivo data on the effect of statins on decellularized cardiovascular implants. Wistar rats with aortic valve insufficiency (day 14) were fed either with a pro-calcific diet (group C; n = 17), or the same diet additionally supplemented with simvastatin (group S; n = 16). Aortic conduits from Sprague-Dawley rats were detergent-decellularized, infrarenally implanted (day 0) in all recipients and explanted at day 28 or day 84. Sonographic competence of the conduit perfusion was 100%, and overall survival amounted to 97%. Simvastatin decreased the low-density lipoprotein cholesterol serum levels; however, it did not affect the calcification of the implants. Histology revealed alpha-smooth muscle actin-positive intima hyperplasia in both groups. Extensive matrix metalloproteinase activity was observed in calcified areas, especially in group S. Quantitative RNA analysis resulted in no differences with regard to several markers of calcifying degeneration (alkaline phosphatase, osteopontin, osteocalcin, osteoprotegerin, bone morphogenetic protein-2, runt-related transcription factor-2) and inflammation (tumor necrosis factor α, interleukin 1β, receptor for advanced glycation end products, CD39, CD73), but significantly lower levels of interleukin-6 in group S. In a standardized small animal model of accelerated cardiovascular calcification, simvastatin failed to diminish the calcification of decellularized aortic conduit implants. This finding confirms the observations of recent clinical trials. However, further experiments are warranted to elucidate the value of partial benefits associated with lower circulating lipid and proinflammatory cytokine levels.

The opioid receptor pharmacology of GSK1521498 compared to other ligands with differential effects on compulsive reward-related behaviours.

PubMed

Kelly, Eamonn; Mundell, Stuart J; Sava, Anna; Roth, Adelheid L; Felici, Antonio; Maltby, Kay; Nathan, Pradeep J; Bullmore, Edward T; Henderson, Graeme

2015-01-01

The novel opioid receptor antagonist, GSK1421498, has been shown to attenuate reward-driven compulsive behaviours, such as stimulant drug seeking or binge eating, in animals and humans. Here, we report new data on the receptor pharmacology of GSK121498, in comparison to naltrexone, naloxone, 6-β-naltrexol and nalmefene. To determine whether the novel opioid antagonist, GSK1521498, is an orthosteric or allosteric antagonist at the μ opioid receptor (MOPr) and whether it has neutral antagonist or inverse agonist properties. A combination of radioligand binding assays and [(35)S]GTPγS binding assays was employed. GSK1521498 completely displaced [(3)H]naloxone binding to MOPr and did not alter the rate of [(3)H]naloxone dissociation from MOPr observations compatible with it binding to the orthosteric site on MOPr. GSK1521498 exhibited inverse agonism when MOPr was overexpressed but not when the level of MOPr expression was low. In parallel studies under conditions of high receptor expression density, naloxone, naltrexone, 6-β-naltrexol and nalmefene exhibited partial agonism, not inverse agonism as has been reported previously for naloxone and naltrexone. In brain tissue from mice receiving a prolonged morphine pre-treatment, GSK1521498 exhibited slight inverse agonism. Differences between GSK1521498 and naltrexone in their effects on compulsive reward seeking are arguably linked to the more selective and complete MOPr antagonism of GSK1521498 versus the partial MOPr agonism of naltrexone. GSK1521498 is also pharmacologically differentiated by its inverse agonist efficacy at high levels of MOPr expression, but this may be less likely to contribute to behavioural differentiation at patho-physiological levels of expression.

Novel shock absorber features varying yield strengths

NASA Technical Reports Server (NTRS)

Geier, D. J.

1964-01-01

A shock absorbent webbing of partially drawn synthetic strands is arranged in sections of varying density related to the varying mass of the human body. This is contoured to protect the body at points of contact, when subjected to large acceleration or deceleration forces.

The structural, electronic and optical properties of Au-ZnO interface structure from the first-principles calculation

NASA Astrophysics Data System (ADS)

Huo, Jin-Rong; Li, Lu; Cheng, Hai-Xia; Wang, Xiao-Xu; Zhang, Guo-Hua; Qian, Ping

2018-03-01

The interface structure, electronic and optical properties of Au-ZnO are studied using the first-principles calculation based on density functional theory (DFT). Given the interfacial distance, bonding configurations and terminated surface, we built the optimal interface structure and calculated the electronic and optical properties of the interface. The total density of states, partial electronic density of states, electric charge density and atomic populations (Mulliken) are also displayed. The results show that the electrons converge at O atoms at the interface, leading to a stronger binding of interfaces and thereby affecting the optical properties of interface structures. In addition, we present the binding energies of different interface structures. When the interface structure of Au-ZnO gets changed, furthermore, varying optical properties are exhibited.

Bypassing the malfunction junction in warm dense matter simulations

NASA Astrophysics Data System (ADS)

Cangi, Attila; Pribram-Jones, Aurora

2015-03-01

Simulation of warm dense matter requires computational methods that capture both quantum and classical behavior efficiently under high-temperature and high-density conditions. The state-of-the-art approach to model electrons and ions under those conditions is density functional theory molecular dynamics, but this method's computational cost skyrockets as temperatures and densities increase. We propose finite-temperature potential functional theory as an in-principle-exact alternative that suffers no such drawback. In analogy to the zero-temperature theory developed previously, we derive an orbital-free free energy approximation through a coupling-constant formalism. Our density approximation and its associated free energy approximation demonstrate the method's accuracy and efficiency. A.C. has been partially supported by NSF Grant CHE-1112442. A.P.J. is supported by DOE Grant DE-FG02-97ER25308.

Selection and Characterization of Dunaliella salina Mutants Defective in Haloadaptation 1

PubMed Central

Chitlaru, Edith; Pick, Uri

1989-01-01

A technique for selection of Dunaliella mutants defective in their capacity to recover from osmotic shocks has been developed. The selection is based on physical separation of mutants on density gradients. This technique takes advantage of the fact that Dunaliella cells, when exposed to osmotic shocks, initially change volume and density due to water gain or loss and subsequently recover their volume and density by readjusting their intracellular glycerol. Eight mutants that do not recover their original density following hyperosmotic shocks have been isolated. The mutants grow similar to wild type cells in 1 molar NaCl, and recover like the wild type from hypotonic shocks but are defective in recovering from hypertonic shocks. A partial characterization of one of the mutants is described. Images Figure 1 PMID:16667101

Understanding the Steric Height Long Term Variability at the Bermuda Atlantic Time-Series Study (BATS) Site with a Neutral Density Approach

NASA Astrophysics Data System (ADS)

Goncalves Neto, A.; Johnson, R. J.; Bates, N. R.

2016-02-01

Rising sea level is one of the main concerns for human life in a scenario with global atmosphere and ocean warming, which is of particular concern for oceanic islands. Bermuda, located in the center of the Sargasso Sea, provides an ideal location to investigate sea level rise since it has a long term tide gauge (1933-present) and is in close proximity to deep ocean time-series sites, namely, Hydrostation `S' (1954-present) and the Bermuda Atlantic Time-Series Study site (1988-present). In this study, we use the monthly CTD deep casts at BATS to compute the contribution of steric height (SH) to the local sea surface height (SSH) for the past 24 years. To determine the relative contribution from the various water masses we first define 8 layers (Surface Layer, Upper Thermocline, Subtropical Mode-Water, Lower Thermocline, Antarctic Intermediate Water, Labrador Sea Water, Iceland-Scotland Overflow Water, Denmark Strait Overflow Water) based on neutral density criteria for which SH is computed. Additionally, we calculate the thermosteric and halosteric components for each of the defined neutral density layers. Surprisingly, the results show that, despite a 3.3mm/yr sea level rise observed at the Bermuda tide gauge, the steric contribution to the SSH at BATS has decreased at a rate of -1.1mm/yr during the same period. The thermal component is found to account for the negative trend in the steric height (-4.4mm/yr), whereas the halosteric component (3.3mm/yr) partially compensates the thermal signal and can be explained by an overall cooling and freshening at the BATS site. Although the surface layer and the upper thermocline waters are warming, all the subtropical and polar water masses, which represent most of the local water column, are cooling and therefore drive the overall SH contribution to the local SSH. Hence, it suggests that the mass contribution to the local SSH plays an important role in the sea level rise, for which we investigate with GRACE data.

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

Braunstein, Samuel L.; Ghosh, Sibasish; Severini, Simone

We reconsider density matrices of graphs as defined in quant-ph/0406165. The density matrix of a graph is the combinatorial Laplacian of the graph normalized to have unit trace. We describe a simple combinatorial condition (the 'degree condition') to test the separability of density matrices of graphs. The condition is directly related to the Peres-Horodecki partial transposition condition. We prove that the degree condition is necessary for separability, and we conjecture that it is also sufficient. We prove special cases of the conjecture involving nearest-point graphs and perfect matchings. We observe that the degree condition appears to have a value beyondmore » the density matrices of graphs. In fact, we point out that circulant density matrices and other matrices constructed from groups always satisfy the condition and indeed are separable with respect to any split. We isolate a number of problems and delineate further generalizations.« less

Underscreening in ionic liquids: a first principles analysis.

PubMed

Rotenberg, Benjamin; Bernard, Olivier; Hansen, Jean-Pierre

2018-02-07

An attempt is made to understand the underscreening effect, observed in concentrated electrolyte solutions or melts, on the basis of simple, admittedly crude models involving charged (for the ions) and neutral (for the solvent molecules) hard spheres. The thermodynamic and structural properties of these 'primitive' and 'semi-primitive' models are calculated within mean spherical approximation, which provides the basic input required to determine the partial density response functions. The screening length [Formula: see text], which is unambiguously defined in terms of the wave-number-dependent response functions, exhibits a cross-over from a low density, Debye-like regime, to a regime where [Formula: see text] increases with density beyond a critical density at which the Debye length [Formula: see text] becomes comparable to the ion diameter. In this high density regime the ratio [Formula: see text] increases according to a power law, in qualitative agreement with experimental measurements, albeit at a much slower rate.

Underscreening in ionic liquids: a first principles analysis

NASA Astrophysics Data System (ADS)

Rotenberg, Benjamin; Bernard, Olivier; Hansen, Jean-Pierre

2018-02-01

An attempt is made to understand the underscreening effect, observed in concentrated electrolyte solutions or melts, on the basis of simple, admittedly crude models involving charged (for the ions) and neutral (for the solvent molecules) hard spheres. The thermodynamic and structural properties of these ‘primitive’ and ‘semi-primitive’ models are calculated within mean spherical approximation, which provides the basic input required to determine the partial density response functions. The screening length λS , which is unambiguously defined in terms of the wave-number-dependent response functions, exhibits a cross-over from a low density, Debye-like regime, to a regime where λS increases with density beyond a critical density at which the Debye length λD becomes comparable to the ion diameter. In this high density regime the ratio λ_S/λD increases according to a power law, in qualitative agreement with experimental measurements, albeit at a much slower rate.

Coarse-grained forms for equations describing the microscopic motion of particles in a fluid.

PubMed

Das, Shankar P; Yoshimori, Akira

2013-10-01

Exact equations of motion for the microscopically defined collective density ρ(x,t) and the momentum density ĝ(x,t) of a fluid have been obtained in the past starting from the corresponding Langevin equations representing the dynamics of the fluid particles. In the present work we average these exact equations of microscopic dynamics over the local equilibrium distribution to obtain stochastic partial differential equations for the coarse-grained densities with smooth spatial and temporal dependence. In particular, we consider Dean's exact balance equation for the microscopic density of a system of interacting Brownian particles to obtain the basic equation of the dynamic density functional theory with noise. Our analysis demonstrates that on thermal averaging the dependence of the exact equations on the bare interaction potential is converted to dependence on the corresponding thermodynamic direct correlation functions in the coarse-grained equations.

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

Smallwood, D.O.

In a previous paper Smallwood and Paez (1991) showed how to generate realizations of partially coherent stationary normal time histories with a specified cross-spectral density matrix. This procedure is generalized for the case of multiple inputs with a specified cross-spectral density function and a specified marginal probability density function (pdf) for each of the inputs. The specified pdfs are not required to be Gaussian. A zero memory nonlinear (ZMNL) function is developed for each input to transform a Gaussian or normal time history into a time history with a specified non-Gaussian distribution. The transformation functions have the property that amore » transformed time history will have nearly the same auto spectral density as the original time history. A vector of Gaussian time histories are then generated with the specified cross-spectral density matrix. These waveforms are then transformed into the required time history realizations using the ZMNL function.« less

Three-dimensional density structure of La Soufrière de Guadeloupe lava dome from simultaneous muon radiographies and gravity data

NASA Astrophysics Data System (ADS)

Rosas-Carbajal, M.; Jourde, Kevin; Marteau, Jacques; Deroussi, Sébastien; Komorowski, Jean-Christophe; Gibert, Dominique

2017-07-01

Muon imaging has recently emerged as a powerful method to complement standard geophysical tools in the understanding of the Earth's subsurface. Muon measurements yield a "radiography" of the average density along the muon path, allowing to image large volumes of a geological body from a single observation point. Here we jointly invert muon data from three simultaneous telescope acquisitions together with gravity data to estimate the three-dimensional density structure of the La Soufrière de Guadeloupe lava dome. Our unique data set allows us to achieve an unprecedented spatial resolution with this novel technique. The retrieved density model reveals an extensive, low-density anomaly where the most active part of the volcanic hydrothermal system is located, supporting previous studies that indicate this region as the most likely to be involved in a partial edifice collapse.

Hypolipidemic action of chrysin on Triton WR-1339-induced hyperlipidemia in female C57BL/6 mice.

PubMed

Zarzecki, Micheli Stéfani; Araujo, Stífani M; Bortolotto, Vandreza C; de Paula, Mariane Trindade; Jesse, Cristiano Ricardo; Prigol, Marina

2014-01-01

Chrysin (5,7-dihydroxyflavone) is a flavonoid, natural component of traditional medicinal herbs, present in honey, propolis and many plant extracts. The objective of this study was to investigate the hypolipidemic properties of chrysin on Triton WR-1339-induced hyperlipidemia in female C57BL/6 mice. Triton WR-1339 was administered intraperitoneally (400 mg/kg) to overnight-fasted mice to develop acute hyperlipidemia. Chrysin was administered orally (10 mg/kg) 30 min before Triton WR-1339. At 24 h after Triton WR-1339 injection, blood samples were collected to measure plasma lipid levels. The hepatic thiobarbituric acid reactive substances (TBARS), carbonyl content, non-protein sulfhydryl (NPSH) and ascorbic acid (AA) levels, as well as catalase (CAT) and superoxide dismutase (SOD) activity were recorded. Chrysin administration significantly decreased total cholesterol levels. In addition, it partially decreased non-high density lipoprotein-cholesterol and triglycerides levels in plasma of hyperlipidaemic mice. In addition chrysin administration prevented the increase on TBARS levels and prevented the decrease in SOD activity induced by Triton WR-1339. These findings indicated that chrysin was able to decrease plasma lipids concentration and that its antioxidant properties was, at least in part, involved in the hypolipidaemic action of chrysin.

Two symmetric n-type interfaces SrTiO{sub 3}/LaAlO{sub 3} in perovskite: Electronic properties from density functional theory

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

Reshak, A. H., E-mail: maalidph@yahoo.co.uk, E-mail: mabujafar@najah.edu; Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis; Abu-Jafar, M. S., E-mail: maalidph@yahoo.co.uk, E-mail: mabujafar@najah.edu

2016-06-28

The first principles study of the (001) two symmetric n-type interfaces between two insulating perovskites, the nonpolar SrTiO{sub 3} (STO), and the polar LaAlO{sub 3} (LAO) was performed. We have analyzed the formation of metallic interface states between the STO and LAO heterointerfaces by using the all-electron full-potential linearized augmented plane-wave approach based on the density functional theory, within the local density approximation, the Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA), and the Engel-Vosko GGA (EVGGA) formalism. It has been found that some bands cross the Fermi energy level (E{sub F}), forming a metallic nature of two symmetric n-type 6.5STO/1.5LAO interfaces withmore » density of states at E{sub F}, N(E{sub F}) of about 3.56 (state/eV/unit cell), and bare electronic specific heat coefficient (γ) of about 0.62 mJ/(mol cell K{sup 2}). The electronic band stature and the partial density of states in the vicinity of E{sub F} are mainly originated from Ti1,2,3,4-3dxy orbitals. These bands are responsible for the metallic behavior and the forming of the Fermi surface of the two symmetric n-type 6.5STO/1.5LAO interfaces. To obtain a clear map of the valence band electronic charge density distribution of the two symmetric n-type 6.5STO/1.5LAO interfaces, we have investigated the bond's nature and the interactions between the atoms. It reveals that the charge is attracted towards O atoms as it is clear that the O atoms are surrounded by uniform blue spheres which indicate the maximum charge accumulation.« less

Discontinuous Galerkin finite element method for solving population density functions of cortical pyramidal and thalamic neuronal populations.

PubMed

Huang, Chih-Hsu; Lin, Chou-Ching K; Ju, Ming-Shaung

2015-02-01

Compared with the Monte Carlo method, the population density method is efficient for modeling collective dynamics of neuronal populations in human brain. In this method, a population density function describes the probabilistic distribution of states of all neurons in the population and it is governed by a hyperbolic partial differential equation. In the past, the problem was mainly solved by using the finite difference method. In a previous study, a continuous Galerkin finite element method was found better than the finite difference method for solving the hyperbolic partial differential equation; however, the population density function often has discontinuity and both methods suffer from a numerical stability problem. The goal of this study is to improve the numerical stability of the solution using discontinuous Galerkin finite element method. To test the performance of the new approach, interaction of a population of cortical pyramidal neurons and a population of thalamic neurons was simulated. The numerical results showed good agreement between results of discontinuous Galerkin finite element and Monte Carlo methods. The convergence and accuracy of the solutions are excellent. The numerical stability problem could be resolved using the discontinuous Galerkin finite element method which has total-variation-diminishing property. The efficient approach will be employed to simulate the electroencephalogram or dynamics of thalamocortical network which involves three populations, namely, thalamic reticular neurons, thalamocortical neurons and cortical pyramidal neurons. Copyright © 2014 Elsevier Ltd. All rights reserved.

Magnetism and charge density wave in GdNiC2 and NdNiC2

NASA Astrophysics Data System (ADS)

Klimczuk, Tom; Kolincio, Kamil; Wianiarski, Michal; Strychalska-Nowak, Judyta; Górnicka, Karolina

The RNiC2 compounds form in an orthorhombic Amm2 crystal structure with Ni and the rare-earth (R) metal chains along the crystallographic a-axis. This system is of particular interest because both a CDW and a long range magnetic ordering phases have been observed together. We report the specific heat, magnetic, magnetotransport and galvanomagnetic properties of GdNiC2 and NdNiC2 antiferromagnets. Complex B-T phase diagrams were built based on the specific heat data. Large negative magnetoresistance due to Zeeman splitting of the electronic bands and partial destruction of a charge density wave ground state is observed above TN. The magnetoresistance and Hall measurements show that at low temperatures a magnetic field induced transformation from antiferromagnetic order to a metamagnetic phase results in the partial suppression of the CDW. This project is financially supported by National Science Centre (Poland), Grant Number: UMO-2015/19/B/ST3/03127.

Asymmetric battery having a semi-solid cathode and high energy density anode

DOEpatents

Tan, Taison; Chiang, Yet-Ming; Ota, Naoki; Wilder, Throop; Duduta, Mihai

2017-11-28

Embodiments described herein relate generally to devices, systems and methods of producing high energy density batteries having a semi-solid cathode that is thicker than the anode. An electrochemical cell can include a positive electrode current collector, a negative electrode current collector and an ion-permeable membrane disposed between the positive electrode current collector and the negative electrode current collector. The ion-permeable membrane is spaced a first distance from the positive electrode current collector and at least partially defines a positive electroactive zone. The ion-permeable membrane is spaced a second distance from the negative electrode current collector and at least partially defines a negative electroactive zone. The second distance is less than the first distance. A semi-solid cathode that includes a suspension of an active material and a conductive material in a non-aqueous liquid electrolyte is disposed in the positive electroactive zone, and an anode is disposed in the negative electroactive zone.

Asymmetric battery having a semi-solid cathode and high energy density anode

DOEpatents

Tan, Taison; Chiang, Yet-Ming; Ota, Naoki; Wilder, Throop; Duduta, Mihai

2016-09-06

Embodiments described herein relate generally to devices, systems and methods of producing high energy density batteries having a semi-solid cathode that is thicker than the anode. An electrochemical cell can include a positive electrode current collector, a negative electrode current collector and an ion-permeable membrane disposed between the positive electrode current collector and the negative electrode current collector. The ion-permeable membrane is spaced a first distance from the positive electrode current collector and at least partially defines a positive electroactive zone. The ion-permeable membrane is spaced a second distance from the negative electrode current collector and at least partially defines a negative electroactive zone. The second distance is less than the first distance. A semi-solid cathode that includes a suspension of an active material and a conductive material in a non-aqueous liquid electrolyte is disposed in the positive electroactive zone, and an anode is disposed in the negative electroactive zone.

Prediction of the electronic structures, thermodynamic and mechanical properties in manganese doped magnesium-based alloys and their saturated hydrides based on density functional theory

NASA Astrophysics Data System (ADS)

Zhang, Ziying; Zhang, Huizhen; Zhao, Hui; Yu, Zhishui; He, Liang; Li, Jin

2015-04-01

The crystal structures, electronic structures, thermodynamic and mechanical properties of Mg2Ni alloy and its saturated hydride with different Mn-doping contents are investigated using first-principles density functional theory. The lattice parameters for the Mn-doped Mg2Ni alloys and their saturated hydrides decreased with an increasing Mn-doping content because of the smaller atomic size of Mn compared with that of Mg. Analysis of the formation enthalpies and electronic structures reveal that the partial substitution of Mg with Mn reduces the stability of Mg2Ni alloy and its saturated hydride. The calculated elastic constants indicate that, although the partial substitution of Mg with Mn lowers the toughness of the hexagonal Mg2Ni alloy, the charge/discharge cycles are elevated when the Mn-doping content is high enough to form the predicted intermetallic compound Mg3MnNi2.

Detonation nanodiamond introduced into samarium doped ceria electrolyte improving performance of solid oxide fuel cell

NASA Astrophysics Data System (ADS)

Pei, Kai; Li, Hongdong; Zou, Guangtian; Yu, Richeng; Zhao, Haofei; Shen, Xi; Wang, Liying; Song, Yanpeng; Qiu, Dongchao

2017-02-01

A novel electrolyte materials of introducing detonation nanodiamond (DNDs) into samarium doped ceria (SDC) is reported here. 1%wt. DNDs doping SDC (named SDC/ND) can enlarge the electrotyle grain size and change the valence of partial ceria. DNDs provide the widen channel to accelerate the mobility of oxygen ions in electrolyte. Larger grain size means that oxygen ions move easier in electrolyte, it can also reduce the alternating current (AC) impedance spectra of internal grains. The lower valence of partial Ce provides more oxygen vacancies to enhance mobility rate of oxygen ions. Hence all of them enhance the transportation of oxygen ions in SDC/ND electrolyte and the OCV. Ultimately the power density of SOFC can reach 762 mw cm-2 at 800 °C (twice higher than pure SDC, which is 319 mw cm-2 at 800 °C), and it remains high power density in the intermediate temperature (600-800 °C). It is relatively high for the electrolyte supported (300 μm) cells.

A frictionally and hydraulically constrained model of the convectively driven mean flow in partially enclosed seas

NASA Astrophysics Data System (ADS)

Maxworthy, T.

1997-08-01

A simple three-layer model of the dynamics of partially enclosed seas, driven by a surface buoyancy flux, is presented. It contains two major elements, a hydraulic constraint at the exit contraction and friction in the interior of the main body of the sea; both together determine the vertical structure and magnitudes of the interior flow variables, i.e. velocity and density. Application of the model to the large-scale dynamics of the Red Sea gives results that are not in disagreement with observation once the model is applied, also, to predict the dense outflow from the Gulf of Suez. The latter appears to be the agent responsible for the formation of dense bottom water in this system. Also, the model is reasonably successful in predicting the density of the outflow from the Persian Gulf, and can be applied to any number of other examples of convectively driven flow in long, narrow channels, with or without sills and constrictions at their exits.

Fuel cell serves as oxygen level detector

NASA Technical Reports Server (NTRS)

1965-01-01

Monitoring the oxygen level in the air is accomplished by a fuel cell detector whose voltage output is proportional to the partial pressure of oxygen in the sampled gas. The relationship between output voltage and partial pressure of oxygen can be calibrated.

Report on the formal specification and partial verification of the VIPER microprocessor

NASA Technical Reports Server (NTRS)

Brock, Bishop; Hunt, Warren A., Jr.

1991-01-01

The formal specification and partial verification of the VIPER microprocessor is reviewed. The VIPER microprocessor was designed by RSRE, Malvern, England, for safety critical computing applications (e.g., aircraft, reactor control, medical instruments, armaments). The VIPER was carefully specified and partially verified in an attempt to provide a microprocessor with completely predictable operating characteristics. The specification of VIPER is divided into several levels of abstraction, from a gate-level description up to an instruction execution model. Although the consistency between certain levels was demonstrated with mechanically-assisted mathematical proof, the formal verification of VIPER was never completed.

Spin-density functional theory treatment of He+-He collisions

NASA Astrophysics Data System (ADS)

Baxter, Matthew; Kirchner, Tom; Engel, Eberhard

2016-09-01

The He+-He collision system presents an interesting challenge to theory. On one hand, a full treatment of the three-electron dynamics constitutes a massive computational problem that has not been attempted yet; on the other hand, simplified independent-particle-model based descriptions may only provide partial information on either the transitions of the initial target electrons or on the transitions of the projectile electron, depending on the choice of atomic model potentials. We address the He+-He system within the spin-density functional theory framework on the exchange-only level. The Krieger-Li-Iafrate (KLI) approximation is used to calculate the exchange potentials for the spin-up and spin-down electrons, which ensures the correct asymptotic behavior of the effective (Kohn-Sham) potential consisting of exchange, Hartree and nuclear Coulomb potentials. The orbitals are propagated with the two-center basis generator method. In each time step, simplified versions of them are fed into the KLI equations to calculate the Kohn-Sham potential, which, in turn, is used to generate the orbitals in the next time step. First results for the transitions of all electrons and the resulting charge-changing total cross sections will be presented at the conference. Work supported by NSERC, Canada.

Phonon induced magnetism in ionic materials

NASA Astrophysics Data System (ADS)

Restrepo, Oscar D.; Antolin, Nikolas; Jin, Hyungyu; Heremans, Joseph P.; Windl, Wolfgang

2014-03-01

Thermoelectric phenomena in magnetic materials create exciting possibilities in future spin caloritronic devices by manipulating spin information using heat. An accurate understanding of the spin-lattice interactions, i.e. the coupling between magnetic excitations (magnons) and lattice vibrations (phonons), holds the key to unraveling their underlying physics. We report ab initio frozen-phonon calculations of CsI that result in non-zero magnetization when the degeneracy between spin-up and spin-down electronic density of states is lifted for certain phonon displacement patterns. For those, the magnetization as a function of atomic displacement shows a sharp resonance due to the electronic states on the displaced Cs atoms, while the electrons on indium form a continuous background magnetization. We relate this resonance to the generation of a two-level system in the spin-polarized Cs partial density of states as a function of displacement, which we propose to be described by a simple resonant-susceptibility model. Current work extends these investigations to semiconductors such as InSb. ODR and WW are supported by the Center for Emergent Materials, an NSF MRSEC at OSU (Grant DMR-0820414).HJ and JPH are supported by AFOSR MURI Cryogenic Peltier Cooling, Contract #FA9550-10-1-0533.

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

DOE PAGES

Krogel, Jaron T.; Santana Palacio, Juan A.; Reboredo, Fernando A.

2016-02-22

Quantum Monte Carlo (QMC) calculations of transition metal oxides are partially limited by the availability of high-quality pseudopotentials that are both accurate in QMC and compatible with major plane-wave electronic structure codes. We have generated a set of neon-core pseudopotentials with small cutoff radii for the early transition metal elements Sc to Zn within the local density approximation of density functional theory. The pseudopotentials have been directly tested for accuracy within QMC by calculating the first through fourth ionization potentials of the isolated transition metal (M) atoms and the binding curve of each M-O dimer. We find the ionization potentialsmore » to be accurate to 0.16(1) eV, on average, relative to experiment. The equilibrium bond lengths of the dimers are within 0.5(1)% of experimental values, on average, and the binding energies are also typically accurate to 0.18(3) eV. The level of accuracy we find for atoms and dimers is comparable to what has recently been observed for bulk metals and oxides using the same pseudopotentials. Our QMC pseudopotential results compare well with the findings of previous QMC studies and benchmark quantum chemical calculations.« less

Defect charge states in Si doped hexagonal boron-nitride monolayer

NASA Astrophysics Data System (ADS)

Mapasha, R. E.; Molepo, M. P.; Andrew, R. C.; Chetty, N.

2016-02-01

We perform ab initio density functional theory calculations to investigate the energetics, electronic and magnetic properties of isolated stoichiometric and non-stoichiometric substitutional Si complexes in a hexagonal boron-nitride monolayer. The Si impurity atoms substituting the boron atom sites SiB giving non-stoichiometric complexes are found to be the most energetically favourable, and are half-metallic and order ferromagnetically in the neutral charge state. We find that the magnetic moments and magnetization energies increase monotonically when Si defects form a cluster. Partial density of states and standard Mulliken population analysis indicate that the half-metallic character and magnetic moments mainly arise from the Si 3p impurity states. The stoichiometric Si complexes are energetically unfavorable and non-magnetic. When charging the energetically favourable non-stoichiometric Si complexes, we find that the formation energies strongly depend on the impurity charge states and Fermi level position. We also find that the magnetic moments and orderings are tunable by charge state modulation q  =  -2, -1, 0, +1, +2. The induced half-metallic character is lost (retained) when charging isolated (clustered) Si defect(s). This underlines the potential of a Si doped hexagonal boron-nitride monolayer for novel spin-based applications.

First-Principles Study of the Band Diagrams and Schottky-Type Barrier Heights of Aqueous Ta3N5 Interfaces.

PubMed

Watanabe, Eriko; Ushiyama, Hiroshi; Yamashita, Koichi

2017-03-22

The photo(electro)chemical production of hydrogen by water splitting is an efficient and sustainable method for the utilization of solar energy. To improve photo(electro)catalytic activity, a Schottky-type barrier is typically useful to separate excited charge carriers in semiconductor electrodes. Here, we focused on studying the band diagrams and the Schottky-type barrier heights of Ta 3 N 5 , which is one of the most promising materials as a photoanode for water splitting. The band alignments of the undoped and n-type Ta 3 N 5 with adsorbents in a vacuum were examined to determine how impurities and adsorbents affect the band positions and Fermi energies. The band edge positions as well as the density of surface states clearly depended on the density of O N impurities in the bulk and surface regions. Finally, the band diagrams of the n-type Ta 3 N 5 /water interfaces were calculated with an improved interfacial model to include the effect of electrode potential with explicit water molecules. We observed partial Fermi level pinning in our calculations at the Ta 3 N 5 /water interface, which affects the driving force for charge separation.

Identification of parameters through which surface chemistry determines the lifetimes of hot electrons in small Au nanoparticles

PubMed Central

Aruda, Kenneth O.; Tagliazucchi, Mario; Sweeney, Christina M.; Hannah, Daniel C.; Schatz, George C.; Weiss, Emily A.

2013-01-01

This paper describes measurements of the dynamics of hot electron cooling in photoexcited gold nanoparticles (Au NPs) with diameters of ∼3.5 nm, and passivated with either a hexadecylamine or hexadecanethiolate adlayer, using ultrafast transient absorption spectroscopy. Fits of these dynamics with temperature-dependent Mie theory reveal that both the electronic heat capacity and the electron–phonon coupling constant are larger for the thiolated NPs than for the aminated NPs, by 40% and 30%, respectively. Density functional theory calculations on ligand-functionalized Au slabs show that the increase in these quantities is due to an increased electronic density of states near the Fermi level upon ligand exchange from amines to thiolates. The lifetime of hot electrons, which have thermalized from the initial plasmon excitation, increases with increasing electronic heat capacity, but decreases with increasing electron–phonon coupling, so the effects of changing surface chemistry on these two quantities partially cancel to yield a hot electron lifetime of thiolated NPs that is only 20% longer than that of aminated NPs. This analysis also reveals that incorporation of a temperature-dependent electron–phonon coupling constant is necessary to adequately fit the dynamics of electron cooling. PMID:23440215

Vertical Mixing in the Dead Sea

NASA Astrophysics Data System (ADS)

Gertman, Isaac; Ozer, Tal; Katsenelson, Boris; Lensky, Nadav

2015-04-01

For hundreds of years, the Dead Sea was characterized by a stable haline stratification, supported by runoff. The penetration of the winter convection was limited to an upper mixed layer (UML) of about 30-50 m. Below the UML, a stable halocline prevented the mixing. As a result of the runoff reduction, the UML salinity increased and the gravitational stability diminished. During the winter of 1978-1979, the sea water overturned, ending the long-term stable hydrological regime. Since 1979, the haline stratification structure reoccurred twice after extremely rainy winters, in 1980-82 and 1992-1995. In other years, the sea was entirely mixed by winter thermal convection ( which occurs from November to March ) and had a seasonal pycnocline beneath the UML during summer. Profiles of temperature and quasi-salinity (density anomaly from 1000 kg/m3 for the chosen reference temperature of 32° C) during the last 19 years, show the formation of summer ``overturning halocline'' beneath the UML, and the thermocline that supports the stable stratification. Another warm and saline layer is formed also during the summer period near the bottom. This layer spreads from the southern part of the sea, where end-brine is discharged to the sea from the Israeli and Jordanian salt plants' evaporation ponds. The end-brine has extremely high salinity (˜ 350 g/kg) and, in spite of the high temperatures ( ˜ 45° C), high density (1350 kg/m^3), it therefore spreads as a gravitational current in the Dead Sea deep basin. Estimation of the density ratio (Rρ) for the Dead Sea water (where measurements of water salinity is quite difficult) was done using quasi-salinity (σ32) and potential temperature (θ): Rρ= [α(partialθ/partial z)]/[β(partial σ32/partial z)], where α and β are temperature expansion and quasi-salinity contraction coefficients respectively. The values of α and β for the Dead Sea water were defined from water samples collected during 2008. The Rρ values confirm that the summer Dead Sea thermohaline structure is appropriate for double diffusion mixing. A salt fingers regime beneath the UML (1.3< Rρ

Coordinated observations of PHEMU at radio wavelengths.

NASA Astrophysics Data System (ADS)

Pluchino, S.; Schillirò, F.; Salerno, E.; Pupillo, G.; Kraus, A.; Mack, K.-H.

We present preliminary results for our study of mutual phenomena of the Galilean satellites performed at radio wavelengths with the Medicina and Noto antennas of the Istituto di Radioastronomia \\textendash{} INAF, and with the Effelsberg 100-m radio telescope of the Max-Planck-Institute for Radioastronomy. Measurements of the radio flux density variation occurred during the mutual occultations of Io by Europa and Ganymede were carried out during the PHEMU09 campaign at K- and Q-band. Flux density variations observed for the first time at radio wavelengths are consistent with the typical optical patterns measured when partial occultations occurred. The flux density drops indicate a non-linear dependence with the percentage of overlapped area.

Equations for O2 and CO2 solubilities in saline and plasma: combining temperature and density dependences.

PubMed

Christmas, Kevin M; Bassingthwaighte, James B

2017-05-01

Solubilities of respiratory gasses in water, saline, and plasma decrease with rising temperatures and solute concentrations. Henry's Law, C = α·P, states that the equilibrium concentration of a dissolved gas is solubility times partial pressure. Solubilities in the water of a solution depend on temperature and the content of other solutes. Blood temperatures may differ more than 20°C between skin and heart, and an erythrocyte will undergo that range as blood circulates. The concentrations of O 2 and CO 2 are the driving forces for diffusion, exchanges, and for reactions. We provide an equation for O 2 and CO 2 solubilities, α, that allows for continuous changes in temperature, T, and solution density, ρ, in dynamically changing states:[Formula: see text]This two-exponential expression with a density scalar γ, and a density exponent β, accounts for solubility changes due to density changes of an aqueous solution. It fits experimental data on solubilities in water, saline, and plasma over temperatures from 20 to 40°C, and for plasma densities, ρ sol up to 1.020 g/ml with ~0.3% error. The amounts of additional bound O 2 (to Hb) and CO 2 (bicarbonate and carbamino) depend on the concentrations in the local water space and the reaction parameters. During exercise, solubility changes are large; both ρ sol and T change rapidly with spatial position and with time. In exercise hemoconcentration plasma, ρ sol exceeds 1.02, whereas T may range over 20°C. The six parameters for O 2 and the six for CO 2 are constants, so solubilities are calculable continuously as T and ρ sol change. NEW & NOTEWORTHY Solubilities for oxygen and carbon dioxide are dependent on the density of the solution, on temperature, and on the partial pressure. We provide a brief equation suitable for hand calculators or mathematical modeling, accounting for these factors over a wide range of temperatures and solution densities for use in rapidly changing conditions, such as extreme exercise or osmotic transients, with better than 0.5% accuracy. Copyright © 2017 the American Physiological Society.

Relationships Between Minimum Alcohol Pricing and Crime During the Partial Privatization of a Canadian Government Alcohol Monopoly.

PubMed

Stockwell, Tim; Zhao, Jinhui; Marzell, Miesha; Gruenewald, Paul J; Macdonald, Scott; Ponicki, William R; Martin, Gina

2015-07-01

The purpose of this study was to estimate the independent effects of increases in minimum alcohol prices and densities of private liquor stores on crime outcomes in British Columbia, Canada, during a partial privatization of off-premise liquor sales. A time-series cross-sectional panel study was conducted using mixed model regression analysis to explore associations between minimum alcohol prices, densities of liquor outlets, and crime outcomes across 89 local health areas of British Columbia between 2002 and 2010. Archival data on minimum alcohol prices, per capita alcohol outlet densities, and ecological demographic characteristics were related to measures of crimes against persons, alcohol-related traffic violations, and non-alcohol-related traffic violations. Analyses were adjusted for temporal and regional autocorrelation. A 10% increase in provincial minimum alcohol prices was associated with an 18.81% (95% CI: ±17.99%, p < .05) reduction in alcohol-related traffic violations, a 9.17% (95% CI: ±5.95%, p < .01) reduction in crimes against persons, and a 9.39% (95% CI: ±3.80%, p < .001) reduction in total rates of crime outcomes examined. There was no significant association between minimum alcohol prices and non-alcohol-related traffic violations (p > .05). Densities of private liquor stores were not significantly associated with alcohol-involved traffic violations or crimes against persons, though they were with non-alcohol-related traffic violations. Reductions in crime events associated with minimum-alcohol-price changes were more substantial and specific to alcohol-related events than the countervailing increases in densities of private liquor stores. The findings lend further support to the application of minimum alcohol prices for public health and safety objectives.

Divertor heat flux mitigation in the National Spherical Torus Experimenta)

NASA Astrophysics Data System (ADS)

Soukhanovskii, V. A.; Maingi, R.; Gates, D. A.; Menard, J. E.; Paul, S. F.; Raman, R.; Roquemore, A. L.; Bell, M. G.; Bell, R. E.; Boedo, J. A.; Bush, C. E.; Kaita, R.; Kugel, H. W.; Leblanc, B. P.; Mueller, D.; NSTX Team

2009-02-01

Steady-state handling of divertor heat flux is a critical issue for both ITER and spherical torus-based devices with compact high power density divertors. Significant reduction of heat flux to the divertor plate has been achieved simultaneously with favorable core and pedestal confinement and stability properties in a highly shaped lower single null configuration in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 2000] using high magnetic flux expansion at the divertor strike point and the radiative divertor technique. A partial detachment of the outer strike point was achieved with divertor deuterium injection leading to peak flux reduction from 4-6MWm-2to0.5-2MWm-2 in small-ELM 0.8-1.0MA, 4-6MW neutral beam injection-heated H-mode discharges. A self-consistent picture of the outer strike point partial detachment was evident from divertor heat flux profiles and recombination, particle flux and neutral pressure measurements. Analytic scrape-off layer parallel transport models were used for interpretation of NSTX detachment experiments. The modeling showed that the observed peak heat flux reduction and detachment are possible with high radiated power and momentum loss fractions, achievable with divertor gas injection, and nearly impossible to achieve with main electron density, divertor neutral density or recombination increases alone.

Ripple structure of crystalline layers in ion-beam-induced Si wafers

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

Hazra, S.; Chini, T.K.; Sanyal, M.K.

Ion-beam-induced ripple formation in Si wafers was studied by two complementary surface sensitive techniques, namely atomic force microscopy (AFM) and depth-resolved x-ray grazing incidence diffraction (GID). The formation of ripple structure at high doses ({approx}7x10{sup 17} ions/cm{sup 2}), starting from initiation at low doses ({approx}1x10{sup 17} ions/cm{sup 2}) of ion beam, is evident from AFM, while that in the buried crystalline region below a partially crystalline top layer is evident from GID study. Such ripple structure of crystalline layers in a large area formed in the subsurface region of Si wafers is probed through a nondestructive technique. The GID techniquemore » reveals that these periodically modulated wavelike buried crystalline features become highly regular and strongly correlated as one increases the Ar ion-beam energy from 60 to 100 keV. The vertical density profile obtained from the analysis of a Vineyard profile shows that the density in the upper top part of ripples is decreased to about 15% of the crystalline density. The partially crystalline top layer at low dose transforms to a completely amorphous layer for high doses, and the top morphology was found to be conformal with the underlying crystalline ripple.« less

Measurement of partial pressures in vacuum technology and vacuum physics

NASA Technical Reports Server (NTRS)

Huber, W. K.

1986-01-01

It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.

Conformational statistics of stiff macromolecules as solutions to partial differential equations on the rotation and motion groups

PubMed

Chirikjian; Wang

2000-07-01

Partial differential equations (PDE's) for the probability density function (PDF) of the position and orientation of the distal end of a stiff macromolecule relative to its proximal end are derived and solved. The Kratky-Porod wormlike chain, the Yamakawa helical wormlike chain, and the original and revised Marko-Siggia models are examples of stiffness models to which the present formulation is applied. The solution technique uses harmonic analysis on the rotation and motion groups to convert PDE's governing the PDF's of interest into linear algebraic equations which have mathematically elegant solutions.

Differential phase measurements of D-region partial reflections

NASA Technical Reports Server (NTRS)

Wiersma, D. J.; Sechrist, C. F., Jr.

1972-01-01

Differential phase partial reflection measurements were used to deduce D region electron density profiles. The phase difference was measured by taking sums and differences of amplitudes received on an array of crossed dipoles. The reflection model used was derived from Fresnel reflection theory. Seven profiles obtained over the period from 13 October 1971 to 5 November 1971 are presented, along with the results from simultaneous measurements of differential absorption. Some possible sources of error and error propagation are discussed. A collision frequency profile was deduced from the electron concentration calculated from differential phase and differential absorption.

Isotope Induced Proton Ordering in Partially Deuterated Aspirin

NASA Astrophysics Data System (ADS)

Schiebel, P.; Papoular, R. J.; Paulus, W.; Zimmermann, H.; Detken, A.; Haeberlen, U.; Prandl, W.

1999-08-01

We report the nuclear density distribution of partially deuterated aspirin, C8H5O4-CH2D, at 300 and 15 K, as determined by neutron diffraction coupled with maximum entropy method image reconstruction. While fully protonated and fully deuterated methyl groups in aspirin are delocalized at low temperatures due to quantum mechanical tunneling, we provide here direct evidence that in aspirin- CH2D at 15 K the methyl hydrogens are localized, while randomly distributed over three sites at 300 K. This is the first observation by diffraction methods of low-temperature isotopic ordering in condensed matter.

X-ray tomography as a non-destructive tool for evaluating the preservation of primary isotope signatures and mineralogy of Mesozoic fossils

NASA Astrophysics Data System (ADS)

Santillan, J. D.; Boyce, J. W.; Eagle, R.; Martin, T.; Tuetken, T.; Eiler, J.

2010-12-01

The stable isotope compositions of carbonate and phosphate components in fossil teeth and bone are widely used to infer information on paleoclimate and the physiology of extinct organisms. Recently the potential for measuring the body temperatures of extinct vertebrates from analyses of 13C-18O bond ordering in fossil teeth has been demonstrated (Eagle et al. 2010). The interpretation of these isotopic signatures relies on an assessment of the resistance of fossil bioapatite to alteration, as diffusion within, and partial recrystallization, or replacement of the original bioapatite will lead to measured compositions that represent mixtures between primary and secondary phases and/or otherwise inaccurate apparent temperatures. X-ray computed tomography (CT) allows 3-D density maps of teeth to be made at micron-scale resolution. Such density maps have the potential to record textural evidence for alteration, recrystallization, or replacement of enamel. Because it is non-destructive, CT can be used prior to stable isotope analysis to identify potentially problematic samples without consuming or damaging scientifically significant specimens. As a test, we have applied CT to tooth fragments containing both dentin and enamel from Late Jurassic sauropods and a Late Cretaceous theropod that yielded a range of clumped isotope temperatures from anomalously high ˜60oC to physiologically plausible ≤40oC. This range of temperatures suggests partial, high-temperature modification of some specimens, but possible preservation of primary signals in others. Three-dimensional CT volumes generated using General Electric Phoenix|x-ray CT instruments were compared with visible light and back-scattered electron images of the same samples. The tube-detector combination used for the CT study consisted of a 180 kV nanofocus transmission tube coupled with a 127 micron pixel pitch detector ( ˜3-12μ m voxel edges), allowing us to clearly map out alteration zones in high contrast, while reducing edge effects and beam hardening artifacts. CT images of these teeth show a range of replacement textures. One tooth -- thought to be the least altered -- shows only localized positive density anomalies near fractures, while a second -- thought to be highly altered -- contains high-density replacement mineralization. A third tooth -- one suspected of possible partial alteration -- shows a network of rectilinear density anomalies in the enamel similar to 2-D transmitted light and back-scattered electron images. This may represent recrystallization or replacement of the primary bioapatite. Unlike 2-D imaging techniques, 3-D volumes can be used to quickly and easily make quantitative measurements of the volumes of altered and unaltered materials: For example, in the enamel of sample 3, we observe a ratio of high density to low density material of ˜ 3:2.

The Density and Compressibility of BaCO3-SrCO3-CaCO3-K2CO3-Na2CO3-Li2CO3 Liquids: New Measurements and a Systematic Trend with Cation Field Strength

NASA Astrophysics Data System (ADS)

Hurt, S. M.; Lange, R. A.; Ai, Y.

2015-12-01

The volumetric properties of multi-component carbonate liquids are required to extend thermodynamic models that describe partial melting of the deep mantle (e.g. pMELTS; Ghiorso et al., 2003) to carbonate-bearing lithologies. Carbonate in the mantle is an important reservoir of carbon, which is released to the atmosphere as CO2 through volcanism, and thus contributes to the carbon cycle. Although MgCO3 is the most important carbonate component in the mantle, it is not possible to directly measure the 1-bar density and compressibility of MgCO3 liquid because, like other alkaline-earth carbonates, it decomposes at a temperature lower than its melting temperature. Despite this challenge, Liu and Lange (2003) and O'Leary et al. (2015) showed that the one bar molar volume, thermal expansion and compressibility of the CaCO3 liquid component could be obtained by measuring the density and sound speeds of stable liquids in the CaCO3-Li2CO3-Na2CO3-K2CO3 quaternary system at one bar. In this study, this same strategy is employed on SrCO3- and BaCO3-bearing alkali carbonate liquids. The density and sound speed of seven liquids in the SrCO3-Li2CO3-Na2CO3-K2CO3 quaternary and three liquids in the BaCO3-Li2CO3-Na2CO3-K2CO3 quaternary were measured from 739-1367K, with SrCO3 and BaCO3 concentrations ranging from 10-50 mol%. The density measurements were made using the double-bob Archimedean method and sound speeds were obtained with a frequency-sweep acoustic interferometer. The molar volume and sound speed measurements were used to calculate the isothermal compressibility of each liquid, and the results show the volumetric properties mix ideally with composition. The partial molar volume and compressibility of the SrCO3 and BaCO3 components are compared to those obtained for the CaCO3 component as a function of cation field strength. The results reveal a systematic trend that allows the partial molar volume and compressibility of the MgCO3 liquid component to be estimated.

Synthesis and characterization of nanoparticles conjugated tannase and using it for enhancement of antibacterial activity of tannase produced by Serratia marcescens.

PubMed

Nsayef Muslim, D Sahira; Abbas Dham, Ziyad; J Mohammed, D Nadheer

2017-09-01

Fourteen isolates of Serratia marcescens were collected from patients suffering from septicemia. All theseisolates revealed different levels in tannase production. Tannase was partially purified from Serratia marcescens b9 by precipitation method at 70% saturation of ammonium sulfate. Au, Pt, SnO 2 and SiO 2 nanoparticles were prepared by laser ablation and examined by transmission electron microscopy (TEM), X-ray diffraction pattern and UV-Visible absorption spectroscopy. Conjugation of SiO 2 nanoparticles to tannase by feeding and pulses methods were prepared and characterized by TEM, X-ray diffraction pattern and UV-Visible spectrum. SiO 2 nanoparticles conjugated partially purified tannase by feeding showed the higher effectiveness and higher significant level against all tested UTI causing in comparison with ciprofloxacin antibiotic, SiO 2 nanoparticles alone, partially purified tannase alone and partially purified tannase by pulses. So that we can conclude that feeding method was the best method for enhancement partially purified tannase activity to maximum level thus SiO 2 nanoparticles conjugated partially purified tannase may be a useful antibacterial agent for the treatment of urinary tract infection. Copyright © 2017 Elsevier Ltd. All rights reserved.

Robust half-metallicity of hexagonal SrNiO{sub 3}

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

Chen, Gao-Yuan; Ma, Chun-Lan, E-mail: machunlan@126.com; Chen, Da

In the rich panorama of the electronic and magnetic properties of 3d transition metal oxides SrMO{sub 3} (M=Ti, V, Cr, Mn, Fe, Co, Ni, Cu), one member (SrNiO{sub 3}) is missing. In this paper we use GGA+U method based on density functional theory to examine its properties. It is found that SrNiO{sub 3} is a ferromagnetic half-metal. The charge density map shows a high degree of ionic bonding between Sr and other atoms. Meanwhile, a covalent-bonding Ni–O–Ni–O–Ni chain is observed. The spin density contour of SrNiO{sub 3} further indicates that the magnetic interaction between Ni atoms mediated by O ismore » semicovalent exchange. The density of states are examined to explore the unusual indirect magnetic-exchange mechanism. Corresponding to the total energies results, a robust half-metallic character is observed, suggesting a promising giant magneto-optical Kerr property of the material. The partial density of states are further examined to explore the origin of ferromagnetic half-metallicity. The O atoms are observed to have larger contribution at fermi level than Ni atoms to the spin-polarized states, demonstrating that O atoms play a critical role in ferromagnetic half-metallicity of SrNiO{sub 3}. Hydrostatic pressure effect is examined to evaluate how robust the half-metallic ferromagnetism is. - Graphical abstract: (a) The total energy as a function of the lattice constant a for hexagonal SrNiO3 with various magnetic phases. (b) The total electronic density of states for hexagonal SrNiO{sub 3} with FM configuration from GGA+U calculations. (c) Total electron-density distribution in the (110) plane. The colors gradually change from cyan (through pink) to yellow corresponding to charge density value from 0 to 4.0. (d) The magnetization density map in the (110) plane. The colors range from blue (through green) to red corresponding to magnetization density value from −0.15 to 0.45. Black and white contours stand for positive and negative values, respectively. - Highlights: • Hexagonal SrNiO{sub 3} is studied using first-principles method for the first time. • It is predicted that SrNiO{sub 3} is a ferromagnetic half metal. • The half-metallic ferromagnetism survives upon a pressure up to 20 GPa.« less

Pressure dependence of effective Coulomb interaction parameters in BaFe2As2 by first-principle calculation

NASA Astrophysics Data System (ADS)

Aghajani, M.; Hadipour, H.; Akhavan, M.

2018-05-01

Pressure dependence of the onsite Coulomb interactions of the BaFe2As2 has been studied by employing the constrained random phase approximation within first-principle calculations. Analyzing total and projected density of states, a pseudogap is found for dxy band at the energy roughly 0.25 eV higher than the Fermi level. Also, by applying pressure the spectral weight of the dxy orbital vanishes while other orbitals remain metallic. The different screening channels, as discussed in four different models, affect significantly on the Hubbard U while the Hund J remains almost unchanged. The average onsite bare and partially and fully screened Coulomb interactions increase with different rates upon compression. These different rates can be explained by competition between the electronic screening and reduction of bond lengths.

Goos-Hänchen shifts of partially coherent light beams from a cavity with a four-level Raman gain medium

NASA Astrophysics Data System (ADS)

Ziauddin; Lee, Ray-Kuang; Qamar, Sajid

2016-09-01

We theoretically investigate spatial and angular Goos-Hänchen (GH) shifts (both negative and positive) in the reflected light for a partial coherent light incident on a cavity. A four-level Raman gain atomic medium is considered in a cavity. The effects of spatial coherence, beam width, and mode index of partial coherent light fields on spatial and angular GH shifts are studied. Our results reveal that a large magnitude of negative and positive GH shifts in the reflected light is achievable with the introduction of partial coherent light fields. Furthermore, the amplitude of spatial (negative and positive) GH shifts are sharply affected by the partial coherent light beam as compared to angular (negative and positive) GH shifts in the reflected light.

The development of an advanced vertical discretisation scheme for a regional ocean model

NASA Astrophysics Data System (ADS)

Bruciaferri, Diego; Shapiro, Georgy; Wobus, Fred

2017-04-01

When designing an ocean model, the choice of the vertical coordinate system must be pursued very carefully (Griffies et al., 2000); especially in those regional areas where local multi-scale processes interact with large-scale oceanographic features. Three main vertical coordinates are usually used in ocean modelling, namely the geopotential, terrain-following and isopycnic, but each one presents its own limitations and strengths. In the last decades, much research has been spent to investigate and develop hybrid approaches able to combine the advantages of each vertical coordinate system but minimising their disadvantages. Here we propose the hybrid s-s-z vertical discretisation scheme, an advanced version of the approach used by Shapiro et al. (2013). In our new scheme, the vertical domain is divided into three zones: in the upper and middle zones use s-coordinates while the deeper zone uses z-levels. The s-s-z vertical grid is introduced into the NEMO (Nucleus for European Modelling of the Ocean) model code and we compare the model skill of our new vertical discretisation scheme with the NEMO vertical grid using z-levels with partial steps through a set of idealized numerical experiments for which analytical solutions or theoretical models exist. Modelling results demonstrate that the magnitude of spurious currents arising from the horizontal pressure gradient errors are of the same order (10 ^ -3 m/s ) both with z-partial steps or with s-s-z vertical grids for the conditions favourable for the geopotential grids ( horizontal initial density levels). For a number of more realistic conditions representing a general cyclonic circulation in the sea, the new discretisation scheme produces smaller spurious currents and hence is more accurate than the z-level approach. Moreover, the enhanced capability of the s-s-z scheme to reproduce dense water cascades as compared to the z-partial steps grid is shown. Finally, we show how the new s-s-z grid can be useful to improve lateral sub-grid-physics parametrisation in ocean model with s-levels. References: Griffies, S. M., Boning, C., Bryan, F. O., Chassignet, E. P., Gerdes, R., Hasumi, H., Hirst, A., Treguier, A.-M., and Webb, D., 2000. Developments in Ocean Climate Modelling, Ocean Modelling, 2, 123-192. Shapiro, G., Luneva, M., Pickering, J., and Storkey, D.: The effect of various vertical discretisation schemes and horizontal diffusion parameterisation on the performance of a 3-D ocean model: the Black Sea case study, Ocean Sci., 9, 377-390, doi:10.5194/os-9-377-2013, 2013.

LIVER REGENERATION STUDIES WITH RAT HEPATOCYTES IN PRIMARY CULTURE

EPA Science Inventory

Adult rat parenchymal hepatocytes in primary culture can be induced to enter into DNA synthesis and mitosis. The optimal conditions for hepatocyte replication are low plating density (less than 10,000 cells/sq cm) and 50% serum from two-thirds partially hepatectomized rats (48 hr...

LATERAL VARIABILITY OF DISSOLVED OXYGEN AND DENSITY IN A SHALLOW, PARTIALLY MIXED ESTUARY. (R826938)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

A data driven method for estimation of B(avail) and appK(D) using a single injection protocol with [¹¹C]raclopride in the mouse.

PubMed

Wimberley, Catriona J; Fischer, Kristina; Reilhac, Anthonin; Pichler, Bernd J; Gregoire, Marie Claude

2014-10-01

The partial saturation approach (PSA) is a simple, single injection experimental protocol that will estimate both B(avail) and appK(D) without the use of blood sampling. This makes it ideal for use in longitudinal studies of neurodegenerative diseases in the rodent. The aim of this study was to increase the range and applicability of the PSA by developing a data driven strategy for determining reliable regional estimates of receptor density (B(avail)) and in vivo affinity (1/appK(D)), and validate the strategy using a simulation model. The data driven method uses a time window guided by the dynamic equilibrium state of the system as opposed to using a static time window. To test the method, simulations of partial saturation experiments were generated and validated against experimental data. The experimental conditions simulated included a range of receptor occupancy levels and three different B(avail) and appK(D) values to mimic diseases states. Also the effect of using a reference region and typical PET noise on the stability and accuracy of the estimates was investigated. The investigations showed that the parameter estimates in a simulated healthy mouse, using the data driven method were within 10±30% of the simulated input for the range of occupancy levels simulated. Throughout all experimental conditions simulated, the accuracy and robustness of the estimates using the data driven method were much improved upon the typical method of using a static time window, especially at low receptor occupancy levels. Introducing a reference region caused a bias of approximately 10% over the range of occupancy levels. Based on extensive simulated experimental conditions, it was shown the data driven method provides accurate and precise estimates of B(avail) and appK(D) for a broader range of conditions compared to the original method. Copyright © 2014 Elsevier Inc. All rights reserved.

Cleaning with a wet sterile gauze significantly reduces contamination of sutures, instruments, and surgical gloves in an ex-vivo pelvic flexure enterotomy model in horses.

PubMed

Giusto, Gessica; Tramuta, Clara; Caramello, Vittorio; Comino, Francesco; Nebbia, Patrizia; Robino, Patrizia; Singer, Ellen; Grego, Elena; Gandini, Marco

2017-01-01

The objective of this study was to investigate whether cleaning surgical materials used to close pelvic flexure enterotomies with a wet sterile gauze will reduce contamination and whether the use of a full thickness appositional suture pattern (F) or a partial thickness inverting (or Cushing) suture pattern (C) would make a difference in the level of contamination. Large colon specimens were assigned to group F or C and divided into subgroups N and G. In group G, a wet sterile gauze was passed over the suture material, another over the instruments, and another over the gloves. In group N, no treatment was applied. The bacterial concentration was measured by optical density (OD) at 24 h. The OD of subgroup CG was lower than that of subgroup CN ( P = 0.019). The OD of subgroup FG was lower than that of subgroup FN ( P = 0.02). The OD of subgroups CG, CN, FG, and FN was lower than that of the negative control ( P < 0.003, P < 0.001, P < 0.001, and P < 0.00). The use of a sterile wet gauze significantly reduced contamination of suture materials. A partial thickness inverting suture pattern did not produce less contamination than a full thickness appositional suture pattern.

Maximally localized Wannier functions in LaMnO3 within PBE + U, hybrid functionals and partially self-consistent GW: an efficient route to construct ab initio tight-binding parameters for eg perovskites.

PubMed

Franchini, C; Kováčik, R; Marsman, M; Murthy, S Sathyanarayana; He, J; Ederer, C; Kresse, G

2012-06-13

Using the newly developed VASP2WANNIER90 interface we have constructed maximally localized Wannier functions (MLWFs) for the e(g) states of the prototypical Jahn-Teller magnetic perovskite LaMnO(3) at different levels of approximation for the exchange-correlation kernel. These include conventional density functional theory (DFT) with and without the additional on-site Hubbard U term, hybrid DFT and partially self-consistent GW. By suitably mapping the MLWFs onto an effective e(g) tight-binding (TB) Hamiltonian we have computed a complete set of TB parameters which should serve as guidance for more elaborate treatments of correlation effects in effective Hamiltonian-based approaches. The method-dependent changes of the calculated TB parameters and their interplay with the electron-electron (el-el) interaction term are discussed and interpreted. We discuss two alternative model parameterizations: one in which the effects of the el-el interaction are implicitly incorporated in the otherwise 'noninteracting' TB parameters and a second where we include an explicit mean-field el-el interaction term in the TB Hamiltonian. Both models yield a set of tabulated TB parameters which provide the band dispersion in excellent agreement with the underlying ab initio and MLWF bands.

Do motivation-related cognitions explain the relationship between perceptions of urban form and neighborhood walking?

PubMed

McCormack, Gavin R; Friedenreich, Christine M; Giles-Corti, Billie; Doyle-Baker, Patricia K; Shiell, Alan

2013-09-01

The built and social environments may contribute to physical activity motivations and behavior. We examined the extent to which the Theory of Planned Behavior (TPB) mediated the association between neighborhood walkability and walking. Two random cross-sectional samples (n = 4422 adults) completed telephone interviews capturing walking-related TPB variables (perceived behavioral control (PBC), attitudes, subjective norm, intention). Of those, 2006 completed a self-administered questionnaire capturing walkability, social support (friends, family, dog ownership), and neighborhood-based transportation (NTW) and recreational walking (NRW). The likelihood of undertaking 1) any vs. none and 2) sufficient vs. insufficient levels (≥150 vs. <150 minutes/week) of NTW and NWR, in relation to walkability, social support, and TPB was estimated. Any and sufficient NTW were associated with access to services, connectivity, residential density, not owning a dog (any NTW only), and friend and family support. Any and sufficient NRW were associated with neighborhood aesthetics (any NRW only), dog ownership, and friend and family support. PBC partially mediated the association between access to services and NTW (any and sufficient), while experiential attitudes partially mediated the association between neighborhood aesthetics and any NRW. Interventions that increase positive perceptions of the built environment may motivate adults to undertake more walking.

Thermally actuated magnetization flux pump in single-grain YBCO bulk

NASA Astrophysics Data System (ADS)

Yan, Yu; Li, Quan; Coombs, T. A.

2009-10-01

Recent progress in material processing has proved that high temperature superconductors (HTS) have a great potential to trap large magnetic fields at cryogenic temperatures. For example, HTS are widely used in MRI scanners and in magnetic bearings. However, using traditional ways to magnetize, the YBCO will always need the applied field to be as high as the expected field on the superconductor or much higher than it, leading to a much higher cost than that of using permanent magnets. In this paper, we find a method of YBCO magnetization in liquid nitrogen that only requires the applied field to be at the level of a permanent magnet. Moreover, rather than applying a pulsed high current field on the YBCO, we use a thermally actuated material (gadolinium) as an intermedia and create a travelling magnetic field through it by changing the partial temperature so that the partial permeability is changed to build up the magnetization of the YBCO gradually after multiple pumps. The gadolinium bulk is located between the YBCO and the permanent magnet and is heated and cooled repeatedly from the outer surface to generate a travelling thermal wave inwards. In the subsequent experiment, an obvious accumulation of the flux density is detected on the surface of the YBCO bulk.

Plasma Homocysteine Is Associated with Increased Oxidative Stress and Antioxidant Enzyme Activity in Welders

PubMed Central

Liu, Hung-Hsin; Shih, Tung-Sheng; Huang, Hsin-Ru; Huang, Shih-Chien; Lee, Lien-Hsiung; Huang, Yi-Chia

2013-01-01

The purpose of this study was to examine the association of vitamin B6 status and plasma homocysteine with oxidative stress and antioxidant capacities in welders. Workers were divided into either the welding exposure group (n = 57) or the nonexposure controls (n = 42) based on whether they were employed as welders. There were no significant differences in vitamin B6 status and plasma homocysteine concentration between the welding exposure group and the nonexposure controls. The welding exposure group had significantly higher levels of oxidized low-density lipoprotein cholesterol and lower erythrocyte glutathione concentration and superoxide dismutase (SOD) activities when compared to nonexposure controls. Plasma pyridoxal 5′-phosphate concentration did not correlate with oxidative stress indicators or antioxidant capacities in either group. However, plasma homocysteine significantly correlated with total antioxidant capacity (TAC) (partial r s = −0.34, P < 0.05) and erythrocyte SOD activities (partial r s = 0.29, P < 0.05) after adjusting for potential confounders in the welding exposure group. In the welding exposure group, adequate vitamin B6 status was not associated with oxidative stress or antioxidant capacities. However, elevated plasma homocysteine seemed to be a major contributing factor to antioxidant capacities (TAC and erythrocyte SOD activities) in welders. PMID:24106453

Local and linear chemical reactivity response functions at finite temperature in density functional theory

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

Franco-Pérez, Marco, E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx; Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México, D.F. 09340; Ayers, Paul W., E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx

2015-12-28

We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dualmore » descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model.« less

Local and linear chemical reactivity response functions at finite temperature in density functional theory.

PubMed

Franco-Pérez, Marco; Ayers, Paul W; Gázquez, José L; Vela, Alberto

2015-12-28

We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model.

A new approach to determine the density of liquids and solids without measuring mass and volume: introducing the solidensimeter

NASA Astrophysics Data System (ADS)

Kiriktaş, Halit; Şahin, Mehmet; Eslek, Sinan; Kiriktaş, İrem

2018-05-01

This study aims to design a mechanism with which the density of any solid or liquid can be determined without measuring its mass and volume in order to help students comprehend the concept of density more easily. The solidensimeter comprises of two scaled and nested glass containers (graduated cylinder or beaker) and sufficient water. In this method, the density measurement was made using the Archimedes’ principle stating that an object fully submerged in a liquid displaces the same amount of liquid as its volume, while an object partially submerged or floating displaces the same amount of liquid as its mass. Using this method, the density of any solids or liquids can be determined using a simple mathematical ratio. At the end of the process a mechanism that helps students to comprehend the density topic more easily was designed. The system is easy-to-design, uses low-cost equipment and enables one to determine the density of any solid or liquid without measuring its mass and volume.

Characterization of Arcjet Flows Using Laser-Induced Fluorescence

NASA Technical Reports Server (NTRS)

Bamford, Douglas J.; O'Keefe, Anthony; Babikian, Dikran S.; Stewart, David A.; Strawa, Anthony W.

1995-01-01

A sensor based on laser-induced fluorescence has been installed at the 20-MW NASA Ames Aerodynamic Heating Facility. The sensor has provided new, quantitative, real-time information about properties of the arcjet flow in the highly dissociated, partially ionized, nonequilibrium regime. Number densities of atomic oxygen, flow velocities, heavy particle translational temperatures, and collisional quenching rates have been measured. These results have been used to test and refine computational models of the arcjet flow. The calculated number densities, translational temperatures, and flow velocities are in moderately good agreement with experiment

The Partial Molar Volume and Compressibility of FeO in CaO-SiO2 Liquids: Systematic Variation with Fe2+ Coordination Change

NASA Astrophysics Data System (ADS)

Guo, X.; Lange, R. A.; Ai, Y.

2009-12-01

Iron is an important element in magmatic liquid, since its concentration can range up to 18% in some basaltic liquids, and it has two oxidation states. In order to model magmatic processes, thermodynamic descriptions of silicate melts must include precise information for both the FeO and Fe2O3 components. Currently, the partial molar volume of FeO is not as well known as that for Fe2O3 because of the difficulty of performing double-bob density measurements under reducing conditions. Yet these data are required in order to convert sound speed measurements on FeO-bearing liquids into compressibility data, which in turn are needed extend density models for magmatic liquids to elevated pressures. Moreover, there is growing evidence from the spectroscopic literature that Fe2+ occurs in 4, 5, and 6-fold coordination in silicate melts, and thus it is possible that the partial molar volume and compressibility of FeO may vary with Fe2+ coordination, and thus with melt composition. To explore these issues, we have conducted both density and relaxed sound speed measurements on liquids in the CaO-FeO-SiO2 system, where the CaO/SiO2 ratio was systematically varied at constant FeO concentration (40 mol%). Density was measured between 1594 and 1813K with the double-bob Archimedean method using molybdenum bobs and crucible in a reducing gas (1%CO-99%Ar) environment. The sounds speeds were measured under similar conditions with a frequency-sweep acoustic interferometer. The derived partial molar volume of FeO increases systematically from 13.7 to 15.2 cm3/mol at 1673 K as the CaO/SiO2 ratio increases and the Fe2+ coordination number decreases. From a comparison with the crystalline volume of FeO (halite structure; 12.06 cm3/mol), which serves as a lower limit for VFeO in silicate liquids when Fe2+ is in 6-fold coordination, we estimate that the average Fe2+ coordination in our experimental melts extends up to values between 5 and 4, consistent with the spectroscopic literature. The partial molar compressibility of FeO also increases systematically as Fe2+ coordination decreases, and its maximum measured value (7.01 x 10-2 GPa-1) is nearly identical to that for the SiO2 component in 4-fold coordination (7.14 x 10-2 GPa-1) and is considerably larger than that for the relatively incompressible component MgO (0.65 x 10-2 GPa-1). Thus, our data indicate that the volumetric properties of FeO component have more in common with those for SiO2 than for MgO.

DFTB3: Extension of the self-consistent-charge density-functional tight-binding method (SCC-DFTB).

PubMed

Gaus, Michael; Cui, Qiang; Elstner, Marcus

2012-04-10

The self-consistent-charge density-functional tight-binding method (SCC-DFTB) is an approximate quantum chemical method derived from density functional theory (DFT) based on a second-order expansion of the DFT total energy around a reference density. In the present study we combine earlier extensions and improve them consistently with, first, an improved Coulomb interaction between atomic partial charges, and second, the complete third-order expansion of the DFT total energy. These modifications lead us to the next generation of the DFTB methodology called DFTB3, which substantially improves the description of charged systems containing elements C, H, N, O, and P, especially regarding hydrogen binding energies and proton affinities. As a result, DFTB3 is particularly applicable to biomolecular systems. Remaining challenges and possible solutions are also briefly discussed.

MAX-DOAS observations from ground, ship, and research aircraft: maximizing signal-to-noise to measure 'weak' absorbers

NASA Astrophysics Data System (ADS)

Volkamer, Rainer; Coburn, Sean; Dix, Barbara; Sinreich, Roman

2009-08-01

Multi AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) instruments, as solar straylight satellites, require an accurate characterization and elimination of Fraunhofer lines from solar straylight spectra to measure the atmospheric column abundance of reactive gases that destroy toxic and heat trapping ozone and form climate cooling aerosols, like glyoxal (CHOCHO), iodine oxide (IO), or bromine oxide (BrO). The currently achievable noise levels with state-of-the-art DOAS instruments are limited to δ'DL ~ 10-4 (noise equivalent differential optical density, δ') further noise reductions are typically not straightforward, and the reason for this barrier is not well understood. Here we demonstrate that the nonlinearity of state-of-the-art CCD detectors poses a limitation to accurately characterize Fraunhofer lines; the incomplete elimination of Fraunhofer lines is found to cause residual structures of δ' ~ 10-4, and only partially accounted by fitting of an "offset" spectrum. We have developed a novel software tool, the CU Data Acquisition Code that overcomes this barrier by actively controlling the CCD saturation level, and demonstrates that δ'DL on the order of 10-5 are possible without apparent limitations from the presence of Fraunhofer lines. The software also implements active control of the elevation angle (angle with respect to the horizon) by means of a Motion Compensation System for use with mobile MAX-DOAS deployments from ships and aircraft. Finally, a novel approach to convert slant column densities into line-of-sight averaged concentrations is discussed.

Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee.

PubMed

Lichtenstein, Alice H; Appel, Lawrence J; Brands, Michael; Carnethon, Mercedes; Daniels, Stephen; Franch, Harold A; Franklin, Barry; Kris-Etherton, Penny; Harris, William S; Howard, Barbara; Karanja, Njeri; Lefevre, Michael; Rudel, Lawrence; Sacks, Frank; Van Horn, Linda; Winston, Mary; Wylie-Rosett, Judith

2006-07-04

Improving diet and lifestyle is a critical component of the American Heart Association's strategy for cardiovascular disease risk reduction in the general population. This document presents recommendations designed to meet this objective. Specific goals are to consume an overall healthy diet; aim for a healthy body weight; aim for recommended levels of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides; aim for normal blood pressure; aim for a normal blood glucose level; be physically active; and avoid use of and exposure to tobacco products. The recommendations are to balance caloric intake and physical activity to achieve and maintain a healthy body weight; consume a diet rich in vegetables and fruits; choose whole-grain, high-fiber foods; consume fish, especially oily fish, at least twice a week; limit intake of saturated fat to <7% of energy, trans fat to <1% of energy, and cholesterol to <300 mg/day by choosing lean meats and vegetable alternatives, fat-free (skim) or low-fat (1% fat) dairy products and minimize intake of partially hydrogenated fats; minimize intake of beverages and foods with added sugars; choose and prepare foods with little or no salt; if you consume alcohol, do so in moderation; and when you eat food prepared outside of the home, follow these Diet and Lifestyle Recommendations. By adhering to these diet and lifestyle recommendations, Americans can substantially reduce their risk of developing cardiovascular disease, which remains the leading cause of morbidity and mortality in the United States.

Contaminant-State Broadening Mechanism in a Driven Dissipative Rydberg System

NASA Astrophysics Data System (ADS)

Porto, J. V.

2017-04-01

The strong interactions in Rydberg atoms make them an ideal system for the study of correlated many-body physics, both in the presence and absence of dissipation. Using such highly excited atomic states requires addressing challenges posed by the dense spectrum of Rydberg levels, the detrimental effects of spontaneous emission, and strong interactions. A full understanding of the scope and limitations of many Rydberg-based proposals requires simultaneously including these effects, which typically cannot be described by a mean-field treatment due to correlations in the quantum coherent and dissipative processes. We study a driven, dissipative system of Rydberg atoms in a 3D optical lattice, and observe substantial deviation from single-particle excitation rates, both on and off resonance. The observed broadened spectra cannot be explained by van der Waals interactions or a mean-field treatment of the system. Based on the magnitude of the broadening and the scaling with density and two-photon Rabi frequency, we attribute these effects to unavoidable blackbody-induced transitions to nearby Rydberg states of opposite parity, which have large, resonant dipole-dipole interactions with the state of interest. Even at low densities of Rydberg atoms, uncontrolled production of atoms in other states significantly modifies the energy levels of the remaining atoms. These off-diagonal exchange interactions result in complex many-body states of the system and have implications for off-resonant Rydberg dressing proposals. This work was partially supported by the ARL-CDQI program.

Experimental measurements concerning the stator insulation partial discharge level of a hydro-generator of high power

NASA Astrophysics Data System (ADS)

Haţiegan, C.; Răduca, E.; Popescu, C.; Hamat, C. O.; Băra, A.; Anghel, D.; Pîrşan, D. A.

2018-01-01

The paper presents a determining and evaluating method from an experimental point of view of the partial discharges level from the insulation of the stator of a synchronous hydro-generator of high power that appear at different temperatures. The temperature is measured directly on the coil with placed thermo-resistant elements between the superior and inferior bars. Also, the level of partial discharges with the coil age in a cold state, at the temperature level of the surrounding environment from within the stator, but also in a warm state at different temperatures, is measured. Through this method there is created the possibility of highlighting some eventual degradations of the coil insulation of a hydro-generator.

Rapid photosynthetic acclimation of Shorea johorensis seedlings after logging disturbance in Central Kalimantan.

PubMed

Clearwater, M J; Susilawaty, R; Effendi, R; van Gardingen, P R

1999-12-01

This study examined the photosynthetic acclimation of pre-existing Shorea johorensis (Dipterocarpaceae) seedlings to the change in conditions that occurs at the time of logging in Central Kalimantan, Indonesia. The hypothesis was that the seedlings would be unable to acclimate beyond partially open conditions after canopy disturbance caused by logging, therefore limiting the potential for regeneration in the most open areas. Bleaching and reductions in the predawn ratio of variable to maximum fluorescence (F v /F m ) indicated chronic photoinhibition and damage to the previously shade-adapted leaves of seedlings in an area logged 2 weeks earlier. The majority of seedlings in partially open and open environments of an area logged 3 months earlier were already growing fast. Leaves that had developed in the new environment showed only small reductions in predawn F v /F m and large increases in the light saturated rate of photosynthesis (A max ) per unit area when compared to shaded seedlings. Leaves in the most open environments had higher but more variable nitrogen concentrations, A max per unit area and A max per unit mass when compared to seedlings in partially open environments. Increases in dark respiration were disproportionately large compared to increases in A max , and may have been the result of increased investment in photoprotective mechanisms. The response of stomatal conductance to the vapour pressure deficit and leaf temperature was examined, but it suggested only a 10% reduction in daily leaf level carbon gain in open environments. The ratio of leaf area to fine root mass was highest in shade-suppressed and newly exposed seedlings, suggesting a potential hydraulic limitation to transpiration during acclimation. However, rainfall during this period was high and leaf water potentials did not differ between disturbed and undisturbed environments. S. johorensis seedlings were capable of significant acclimation to conditions more extreme than partial canopy opening. Low seedling density after logging during the wet season cannot be explained by a limited potential for photosynthetic acclimation.

Phantom studies investigating extravascular density imaging for partial volume correction of 3-D PET /sup 18/FDG studies

NASA Astrophysics Data System (ADS)

Wassenaar, R. W.; Beanlands, R. S. B.; deKemp, R. A.

2004-02-01

Limited scanner resolution and cardiac motion contribute to partial volume (PV) averaging of cardiac PET images. An extravascular (EV) density image, created from the subtraction of a blood pool scan from a transmission image, has been used to correct for PV averaging in H/sub 2//sup 15/O studies using 2-D imaging but not with 3-D imaging of other tracers such as /sup 18/FDG. A cardiac phantom emulating the left ventricle was used to characterize the method for use in 3-D PET studies. Measurement of the average myocardial activity showed PV losses of 32% below the true activity (p<0.001). Initial application of the EV density correction still yielded a myocardial activity 13% below the true value (p<0.001). This failure of the EV density image was due to the 1.66 mm thick plastic barrier separating the myocardial and ventricular chambers within the phantom. Upon removal of this artifact by morphological dilation of the blood pool, the corrected myocardial value was within 2% of the true value (p=ns). Spherical ROIs (diameter of 2 to 10 mm), evenly distributed about the myocardium, were also used to calculate the average activity. The EV density image was able to account for PV averaging throughout the range of diameters to within a 5% accuracy, however, a small bias was seen as the size of the ROIs increased. This indicated a slight mismatch between the emission and transmission image resolutions, a result of the difference in data acquisitions (i.e., span and ring difference) and default smoothing. These results show that the use of EV density image to correct for PV averaging is possible with 3-D PET. A method of correcting barrier effects in phantoms has been presented, as well as a process for evaluating resolution mismatch.

A role for charcoal's physical properties in its carbon cycle fluxes

NASA Astrophysics Data System (ADS)

Masiello, C. A.; Dugan, B.; Gao, X.; Pyle, L.; Sorrenti, G.; LaMere, L.; Liu, Z.; Zygourakis, K.

2016-12-01

The production of charcoal by fire generates a pool of soil carbon that is more biologically resistant to decomposition than many other forms of soil organic matter, and in some cases charcoal accumulates on the landscape. In other situations, however, charcoal does not accumulate, and is rapidly lost to rivers and eventually delivered to the ocean, where it can form a significant component of sedimentary organic carbon. The physical properties of charcoal form one basic dimension controlling whether charcoal is stored on the landscape or whether it moves to rivers and eventually marine sediments. It is simple to understand how charcoal density and porosity can play a crucial role in its mobility on the landscape: when charcoal pores are filled with air, the bulk density of charcoal can be as low as 0.25 g/cm3, and it will float and thus is easily transported with water runoff. As pores fill with water or soil minerals, the bulk density increases and can exceed 1 g/cm3, which will promote sinking and decrease mobility. For example, a charcoal with an internal porosity of 30% must have 90% of the pores saturated with water to achieve a bulk density greater than 1 g/cm3. Alternately for that same charcoal 20% of charcoal pores would need to infill with soil minerals (mineral density = 3.8 g/cm3) to achieve a density greater than 1 g/cm3. This mineral-infilling process has not been widely observed. Instead, early laboratory and field data suggest that the soil minerals partially block pores in charcoal and this process slows the rate of water transport into charcoal pores. If widespread, this process of partial pore throat occlusion may limit the rate of biochar saturation and thus help control the long-term landscape fate of charcoal.

The timing and intensity of column collapse during explosive volcanic eruptions

NASA Astrophysics Data System (ADS)

Carazzo, Guillaume; Kaminski, Edouard; Tait, Stephen

2015-02-01

Volcanic columns produced by explosive eruptions commonly reach, at some stage, a collapse regime with associated pyroclastic density currents propagating on the ground. The threshold conditions for the entrance into this regime are mainly controlled by the mass flux and exsolved gas content at the source. However, column collapse is often partial and the controls on the fraction of total mass flux that feeds the pyroclastic density currents, defined here as the intensity of collapse, are unknown. To better understand this regime, we use a new experimental apparatus reproducing at laboratory scale the convecting and collapsing behavior of hot particle-laden air jets. We validate the predictions of a 1D theoretical model for the entrance into the regime of partial collapse. Furthermore, we show that where a buoyant plume and a collapsing fountain coexist, the intensity of collapse can be predicted by a universal scaling relationship. We find that the intensity of collapse in the partial collapse regime is controlled by magma gas content and temperature, and always exceeds 40%, independent of peak mass flux and total erupted volume. The comparison between our theoretical predictions and a set of geological data on historic and pre-historic explosive eruptions shows that the model can be used to predict both the onset and intensity of column collapse, hence it can be used for rapid assessment of volcanic hazards notably ash dispersal during eruptive crises.

Experimental level densities of atomic nuclei

DOE PAGES

Guttormsen, M.; Aiche, M.; Bello Garrote, F. L.; ...

2015-12-23

It is almost 80 years since Hans Bethe described the level density as a non-interacting gas of protons and neutrons. In all these years, experimental data were interpreted within this picture of a fermionic gas. However, the renewed interest of measuring level density using various techniques calls for a revision of this description. In particular, the wealth of nuclear level densities measured with the Oslo method favors the constant-temperature level density over the Fermi-gas picture. Furthermore, trom the basis of experimental data, we demonstrate that nuclei exhibit a constant-temperature level density behavior for all mass regions and at least upmore » to the neutron threshold.« less

High hydrostatic pressure extract of garlic increases the HDL cholesterol level via up-regulation of apolipoprotein A-I gene expression in rats fed a high-fat diet

PubMed Central

2012-01-01

Background Cardiovascular disease (CVD) is the number one cause of mortality worldwide and a low high-density lipoprotein cholesterol (HDL-C) level is an important marker of CVD risk. Garlic (Allium sativum) has been widely used in the clinic for treatment of CVD and regulation of lipid metabolism. This study investigated the effects of a high hydrostatic pressure extract of garlic (HEG) on HDL-C level and regulation of hepatic apolipoprotein A-I (apoA-I) gene expression. Methods Male Sprague–Dawley rats were divided into two groups and maintained on a high-fat control diet (CON) or high-fat control diet supplemented with high hydrostatic pressure extract of garlic (HEG) for 5 weeks. Changes in the expression of genes related to HDL-C metabolism were analyzed in liver, together with biometric and blood parameters. Results In the HEG group, the plasma triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) levels were significantly decreased in comparison with the CON group (P < 0.05). Dietary HEG also lowered the hepatic TG and total cholesterol (TC) levels compared to the CON group. While the plasma HDL-C level and mRNA level of hepatic apoA-I, which is one of primarily proteins of HDL-C particle, were significantly increased in the HEG group compared to the CON group (P < 0.05). The gene expression of ATP-binding cassette transporter A1 (ABCA1) and lecithin:cholesterol acyltransferase (LCAT), importantly involved in the biogenesis in HDL, were also up-regulated by dietary HEG. Conclusions These results suggest that HEG ameliorates plasma lipid profiles and attenuates hepatic lipid accumulation in the high-fat fed rats. Our findings provides that the effects of HEG on the increase of the plasma HDL-C level was at least partially mediated by up-regulation of hepatic genes expression such as apoA-I, ABCA1, and LCAT in rats fed a high-fat diet. PMID:22713542

Theory of advection-driven long range biotic transport

USDA-ARS?s Scientific Manuscript database

We propose a simple mechanistic model to examine the effects of advective flow on the spread of fungal diseases spread by wind-blown spores. The model is defined by a set of two coupled non-linear partial differential equations for spore densities. One equation describes the long-distance advectiv...

LATERAL VARIABILITY OF DISSOLVED OXYGEN AND DENSITY IN A SHALLOW, PARTIALLY MIXED ESTUARY. (R828677C001)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Computerized algorithms for partial cuts

Treesearch

R.L. Ernst; S.L. Stout

1991-01-01

Stand density, stand structure (diameter distribution), and species composition are all changed by intermediate treatments in forest stands. To use computer stand-growth simulators to assess the effects of different treatments on stand growth and development, users must be able to duplicate silviculturally realistic treatments in the simulator. In this paper, we review...

Solute-solvent interactions in 2,4-dihydroxyacetophenone isonicotinoylhydrazone solutions in N, N-dimethylformamide and dimethyl sulfoxide at 298-313 K on ultrasonic and viscometric data

NASA Astrophysics Data System (ADS)

Dikkar, A. B.; Pethe, G. B.; Aswar, A. S.

2016-02-01

The speed of sound ( u), density (ρ), and viscosity (η) of 2,4-dihydroxyacetophenone isonicotinoylhydrazone (DHAIH) have been measured in N, N-dimethyl formamide and dimethyl sulfoxide at equidistance temperatures 298.15, 303.15, 308.15, and 313.15 K. These data were used to calculate some important ultrasonic and thermodynamic parameters such as apparent molar volume ( V ϕ s st ), apparent molar compressibility ( K ϕ), partial molar volume ( V ϕ 0 ) and partial molar compressibility ( K ϕ 0 ), were estimated by using the values of ( V ϕ 0 ) and ( K ϕ), at infinite dilution. Partial molar expansion at infinite dilution, (ϕ E 0 ) has also been calculated from temperature dependence of partial molar volume V ϕ 0 . The viscosity data have been analyzed using the Jones-Dole equation, and the viscosity, B coefficients are calculated. The activation free energy has been calculated from B coefficients and partial molar volume data. The results have been discussed in the term of solute-solvent interaction occurring in solutions and it was found that DHAIH acts as a structure maker in present systems.

Pricing timer options and variance derivatives with closed-form partial transform under the 3/2 model

PubMed Central

Zheng, Wendong; Zeng, Pingping

2016-01-01

ABSTRACT Most of the empirical studies on stochastic volatility dynamics favour the 3/2 specification over the square-root (CIR) process in the Heston model. In the context of option pricing, the 3/2 stochastic volatility model (SVM) is reported to be able to capture the volatility skew evolution better than the Heston model. In this article, we make a thorough investigation on the analytic tractability of the 3/2 SVM by proposing a closed-form formula for the partial transform of the triple joint transition density which stand for the log asset price, the quadratic variation (continuous realized variance) and the instantaneous variance, respectively. Two distinct formulations are provided for deriving the main result. The closed-form partial transform enables us to deduce a variety of marginal partial transforms and characteristic functions and plays a crucial role in pricing discretely sampled variance derivatives and exotic options that depend on both the asset price and quadratic variation. Various applications and numerical examples on pricing moment swaps and timer options with discrete monitoring feature are given to demonstrate the versatility of the partial transform under the 3/2 model. PMID:28706460

Intelligent driving in traffic systems with partial lane discipline

NASA Astrophysics Data System (ADS)

Assadi, Hamid; Emmerich, Heike

2013-04-01

It is a most common notion in traffic theory that driving in lanes and keeping lane changes to a minimum leads to smooth and laminar traffic flow, and hence to increased traffic capacity. On the other hand, there exist persistent vehicular traffic systems that are characterised by habitual disregarding of lane markings, and partial or complete loss of laminar traffic flow. Here, we explore the stability of such systems through a microscopic traffic flow model, where the degree of lane-discipline is taken as a variable, represented by the fraction of drivers that disregard lane markings completely. The results show that lane-free traffic may win over completely ordered traffic at high densities, and that partially ordered traffic leads to the poorest overall flow, while not considering the crash probability. Partial order in a lane-free system is similar to partial disorder in a lane-disciplined system in that both lead to decreased traffic capacity. This could explain the reason why standard enforcement methods, which rely on continuous increase of order, often fail to incur order to lane-free traffic systems. The results also provide an insight into the cooperative phenomena in open systems with self-driven particles.

Silicate melts density, buoyancy relations and the dynamics of magmatic processes in the upper mantle

NASA Astrophysics Data System (ADS)

Sanchez-Valle, Carmen; Malfait, Wim J.

2016-04-01

Although silicate melts comprise only a minor volume fraction of the present day Earth, they play a critical role on the Earth's geochemical and geodynamical evolution. Their physical properties, namely the density, are a key control on many magmatic processes, including magma chamber dynamics and volcanic eruptions, melt extraction from residual rocks during partial melting, as well as crystal settling and melt migration. However, the quantitative modeling of these processes has been long limited by the scarcity of data on the density and compressibility of volatile-bearing silicate melts at relevant pressure and temperature conditions. In the last decade, new experimental designs namely combining large volume presses and synchrotron-based techniques have opened the possibility for determining in situ the density of a wide range of dry and volatile-bearing (H2O and CO2) silicate melt compositions at high pressure-high temperature conditions. In this contribution we will illustrate some of these progresses with focus on recent results on the density of dry and hydrous felsic and intermediate melt compositions (rhyolite, phonolite and andesite melts) at crustal and upper mantle conditions (up to 4 GPa and 2000 K). The new data on felsic-intermediate melts has been combined with in situ data on (ultra)mafic systems and ambient pressure dilatometry and sound velocity data to calibrate a continuous, predictive density model for hydrous and CO2-bearing silicate melts with applications to magmatic processes down to the conditions of the mantle transition zone (up to 2773 K and 22 GPa). The calibration dataset consist of more than 370 density measurements on high-pressure and/or water-and CO2-bearing melts and it is formulated in terms of the partial molar properties of the oxide components. The model predicts the density of volatile-bearing liquids to within 42 kg/m3 in the calibration interval and the model extrapolations up to 3000 K and 100 GPa are in good agreement with results from ab initio calculations. The density model has been applied to examine the mineral-melt buoyancy relations at depth and the implications of these results for the dynamics of magma chambers, crystal settling and the stability and mobility of magmas in the upper mantle will be discussed.

3-D density modeling of Mt. Paekdu (N Korea/China) stratovolcano and its evolution by a combination of EGM2008/terrestrial gravity field

NASA Astrophysics Data System (ADS)

Götze, Hans-Jürgen; Choi, Sungchan

2015-04-01

We combined the global gravity dataset EGM2008 and a local terrestrial gravity data survey to conduct constrained 3-D crustal density modeling of a strato-volcanic complex and the surrounding area located close to the border of North Korea and China. The independent geophysical (seismic, seismology, geochemistry) and petrological constraints will be presented together with the preprocessing of data base by curvature analysis and Euler deconvolution. The multiple data base is used to assist a general interpretation of the investigated area, and the 3D density model (modelled by the in-house IGMAS+ software). Mt. Paekdu is characterized by a low of Bouguer anomaly of some -110 × 10-5 m/s2, which is caused by the combined gravity effects of (1) Moho depth of about 40 km, (2) a zone with both lower P-wave velocity and density than the surrounding, (3) low density volcanic rocks at the surface, and (4) the presence of a magma chamber that has not previously been identified. The terrestrial gravity field measured along the seismic profile shows a remarkable anomaly descending from the southern- to the northern flank of the Mt. Paekdu volcano, which should be a typical anomaly pattern generally observed over the active volcanic area in the world (e.g. the Yellow Stone volcano). The trend is interpreted to be caused by a prominent density difference between a serious of high density mid crustal sill beneath the southern flank and a predicted partial melted zone locating in the northern flank. With the help of several geoscientific observations (seismic, electromagnetic, gravity and geochemistry) and the 3D density model we conclude that a high density sill was formed in Pliocene and early Pleistocene after pre-shield plateau-forming eruption. Since the Pliocene, volcanic activity in the Mt. Paekdu region might be migrated from the southeastern of North Korea to the northwest, following the path of NW-SE-trending faults. Recently observed seismic tremors can be explained by the vertical movement of the partial melted magma chamber beneath the northern part of the Mt. Baekdu volcanic area, which is confirmed by vertical stress change calculation.

3-D Density Modeling of the Combined EGM2008/Terrestrial Gravity Field over the Mt. Paekdu (N Korea/China) Stratovolcano and Its Evolution

NASA Astrophysics Data System (ADS)

Goetze, H. J.; Choi, S.

2014-12-01

In the presentation we get use of the global gravity dataset EGM2008 and a local terrestrial gravity data survey for a constrained 3-D crustal density modeling of a stratovolcano and its surrounding area located close to the border of North Korea and China. The independent geophysical (seismic, seismology, geochemistry) and petrological constraints will be presented together with the preprocessing of data base by curvature analysis and Euler deconvolution. The multiple data base is used to assist a general interpretation of the investigated area in time, and the 3D density model (modelled by the inhouse IGMAS+ software). Mt. Paekdu is characterized by a low of Bouguer anomaly of some -110 ´ 10-5 m/s2, which is caused by the combined gravity effects of (1) Moho depth of about 40 km, (2) a zone with both lower P-wave velocity and density than the surrounding, (3) low density volcanic rocks at the surface, and (4) the presence of a magma chamber that has not previously been identified. The terrestrial gravity field measured along the seismic profile shows a remarkable anomaly descending from the southern- to the northern flank of the Mt. Paekdu volcano, which should be a typical anomaly pattern generally obsered over the active volcanic area in the world (e.g. the Yellow Stone volcano). The trend is interpreted to be caused by a prominent density difference between a serious of high density mid crustal sill beneath the southern flank and a predicted partial melted zone locating in the northern flank. With the help of several geoscientific observations (seismic, electromagnetic, gravity and geochemistry) and the 3D density model we conclude that a high density sill was formed in Pliocene and early Pleistocene after pre-shield plateau-forming eruption. Since the Pliocene, volcanic activity in the Mt. Paekdu region might be migrated from the southeastern of North Korea to the northwest, following the path of NW-SE-trending faults. Recently observed seismic tremors can be explained by the vertical movement of the partial melted magma chamber beneath the northern part of the Mt. Baekdu volcanic area, which is confirmed by vertical stress calculation.

Atypical water lattices and their possible relevance to the amorphous ices: A density functional study

NASA Astrophysics Data System (ADS)

Anick, David J.

2013-04-01

Of the fifteen known crystalline forms of ice, eleven consist of a single topologically connected hydrogen bond network with four H-bonds at every O. The other four, Ices VI-VIII and XV, consist of two topologically connected networks, each with four H-bonds at every O. The networks interpenetrate but do not share H-bonds. This article presents two new periodic water lattice families whose topological connectivity is "atypical": they consist of many two-dimensional layers that share no H-bonds. Layers are held together only by dispersion forces. Within each layer there are still four H-bonds at each O. Called "Hexagonal Bilayer Water" (HBW) and "Pleated Sheet Water" (PSW), they have computed densities of about 1.1 g/mL and 1.3 g/mL respectively, and nearest neighbor O-coordination is 4.5 to 5.5 and 6 to 8 respectively. Using density functional theory (BLYP-D/TZVP), various proton ordered forms of HBW and PSW are optimized and categorized. There are simple pathways connecting Ice-Ih to HBW and HBW to PSW. Their computed properties suggest similarities to the high density and very high density amorphous ices (HDA and VHDA) respectively. It is unknown whether HDA, VHDA, and Low Density Amorphous Ice (LDA) are fully disordered glasses down to the molecular level, or whether there is some short-range local order. Based on estimated radial distribution functions (RDFs), one proton ordered form of HBW matches HDA best. The idea is explored that HDA could contain islands with this underlying structure, and likewise, that VHDA could contain regions of PSW. A "microlattice model version 1" (MLM1) is presented as a device to compare key experimental data on the amorphous ices with these atypical structures and with a microlattice form of Ice-XI for LDA. Resemblances are found with the amorphs' RDFs, densities, Raman spectra, and transition behaviors. There is not enough information in the static models to assign either a microlattice structure or a partial microlattice structure to any amorphous ice phase.

Single-crystal study of the charge density wave metal LuNiC2

NASA Astrophysics Data System (ADS)

Steiner, S.; Michor, H.; Sologub, O.; Hinterleitner, B.; Höfenstock, F.; Waas, M.; Bauer, E.; Stöger, B.; Babizhetskyy, V.; Levytskyy, V.; Kotur, B.

2018-05-01

We report on single-crystal growth, single-crystal x-ray diffraction, physical properties, and density functional theory (DFT) electronic structure as well as Fermi surface calculations for two ternary carbides, LuCoC2 and LuNiC2. Electrical resistivity measurements reveal for LuNiC2 a charge density wave (CDW) transition at TCDW≃450 K and, for T >TCDW , a significant anisotropy of the electrical resistivity, which is lowest along the orthorhombic a axis. The analysis of x-ray superstructure reflections suggest a commensurate CDW state with a Peierls-type distortion of the Ni atom periodicity along the orthorhombic a axis. DFT calculations based on the CDW modulated monoclinic structure model of LuNiC2 as compared to results of the orthorhombic parent type reveal the formation of a partial CDW gap at the Fermi level which reduces the electronic density of states from N (EF)=1.03 states/eV f.u. without CDW to N (EF)=0.46 states/eV f.u. in the CDW state. The corresponding bare DFT Sommerfeld value of the latter, γDFTCDW=0.90 mJ/mol K2, reaches reasonable agreement with the experimental value γ =0.83 (5 ) mJ/mol K2 of LuNiC2. LuCoC2 displays a simple metallic behavior with neither CDW ordering nor superconductivity above 0.4 K. Its experimental Sommerfeld coefficient, γ =5.9 (1) mJ/mol K2, is in realistic correspondence with the calculated, bare Sommerfeld coefficient, γDFT=3.82 mJ/mol K2, of orthorhombic LuCoC2.

Associations of serum adiponectin with skeletal muscle morphology and insulin sensitivity.

PubMed

Ingelsson, Erik; Arnlöv, Johan; Zethelius, Björn; Vasan, Ramachandran S; Flyvbjerg, Allan; Frystyk, Jan; Berne, Christian; Hänni, Arvo; Lind, Lars; Sundström, Johan

2009-03-01

Skeletal muscle morphology and function are strongly associated with insulin sensitivity. The objective of the study was to test the hypothesis that circulating adiponectin is associated with skeletal muscle morphology and that adiponectin mediates the relation of muscle morphology to insulin sensitivity. This was a cross-sectional investigation of 461 men aged 71 yr, participants of the community-based Uppsala Longitudinal Study of Adult Men study. Measures included serum adiponectin, insulin sensitivity measured with euglycemic insulin clamp technique, and capillary density and muscle fiber composition determined from vastus lateralis muscle biopsies. In multivariable linear regression models (adjusting for age, physical activity, fasting glucose, and pharmacological treatment for diabetes), serum adiponectin levels rose with increasing capillary density (beta, 0.30 per 50 capillaries per square millimeter increase; P = 0.041) and higher proportion of type I muscle fibers (beta, 0.27 per 10% increase; P = 0.036) but declined with a higher proportion of type IIb fibers (beta, -0.39 per 10% increase; P = 0.014). Using bootstrap methods to examine the potential role of adiponectin in associations between muscle morphology and insulin sensitivity and the associations of capillary density (beta difference, 0.041; 95% confidence interval 0.001, 0.085) and proportion of type IIb muscle fibers (beta difference, -0.053; 95% confidence interval -0.107, -0.002) with insulin sensitivity were significantly attenuated when adiponectin was included in the models. Circulating adiponectin concentrations were higher with increasing skeletal muscle capillary density and in individuals with higher proportion of slow oxidative muscle fibers. Furthermore, our results indicate that adiponectin could be a partial mediator of the relations between skeletal muscle morphology and insulin sensitivity.

Generalized Reduction Formula for Discrete Wigner Functions of Multiqubit Systems

NASA Astrophysics Data System (ADS)

Srinivasan, K.; Raghavan, G.

2018-03-01

Density matrices and Discrete Wigner Functions are equally valid representations of multiqubit quantum states. For density matrices, the partial trace operation is used to obtain the quantum state of subsystems, but an analogous prescription is not available for discrete Wigner Functions. Further, the discrete Wigner function corresponding to a density matrix is not unique but depends on the choice of the quantum net used for its reconstruction. In the present work, we derive a reduction formula for discrete Wigner functions of a general multiqubit state which works for arbitrary quantum nets. These results would be useful for the analysis and classification of entangled states and the study of decoherence purely in a discrete phase space setting and also in applications to quantum computing.

Physicochemical properties and ion-solvent interactions in aqueous sodium, ammonium, and lead acetate solution

NASA Astrophysics Data System (ADS)

Deosarkar, S. D.; Mendkudle, M. S.

2014-09-01

Densities (ρ), viscosities (η) and refractive indices ( n D) of aqueous sodium acetate (SA), ammonium acetate (AA), and lead acetate (LA) solutions have been measured for different concentrations of salts at 302.15 K. Apparent molar volumes (φv) for studied solutions were calculated from density data, and fitted to Masson's relation and partial molar volume (φ{v/o}) was determined. Viscosity data were fitted to Jones-Dole equation and viscosity A- and B-coefficients were determined. Refractive index and density data were fitted to Lorentz and Lorenz equation and specific refraction ( R D) were calculated. Behavior of various physicochemical properties indicated presence of strong ion-solvent interactions in present systems and the acetate salts structure maker in water.

The resolved layer of a collisionless, high beta, supercritical, quasi-perpendicular shock wave. I - Rankine-Hugoniot geometry, currents, and stationarity

NASA Technical Reports Server (NTRS)

Scudder, J. D.; Aggson, T. L.; Mangeney, A.; Lacombe, C.; Harvey, C. C.

1986-01-01

Data collected by the ISEE dual-spacecraft mission (on November 7, 1977) on a slowly moving, supercritical, high-beta, quasi-perpendicular bow shock are presented, and the local geometry, spatial scales, and stationarity of this shock wave are assessed in a self-consistent Rankine-Hugoniot-constrained frame of reference. Included are spatial profiles of the ac and dc magnetic and electric fields, electron and proton fluid velocities, current densities, electron and proton number densities, temperatures, pressures, and partial densities of the reflected protons. The observed layer profile is shown to be nearly phase standing and one-dimensional in a Rankine-Hugoniot frame, empirically determined by the magnetofluid parameters outside the layer proper.

Egg production patterns of two invertebrate species in rocky subtidal areas under different fishing regimes along the coast of central Chile

PubMed Central

Ospina-Álvarez, Andres; González, Catherine; Fernández, Miriam

2017-01-01

Fishing is a major source of human impact, reducing density and size of a wide range of exploited species in comparison to areas exhibiting strong regulations (no-take and partially protected areas, including Territorial Use Rights for Fisheries, TURFs). Since size and density might have important consequences on reproduction, and therefore natural re-seeding, we monitored adult size, density and potential fecundity of the keyhole limpet (Fissurella latimarginata) and the red sea urchin (Loxechinus albus) in areas under two fishing regimes (TURFs and Open Access Areas, OAAs). Analyzing the distribution of suitable habitats, we predict spatial patterns of potential egg production, to identify reproductive hotspots along the central coast of Chile. The current system of TURFs in central Chile showed higher potential egg production of F. latimarginata and of L. albus than expected under a complete OAAs scenario (67 and 52% respectively). Potential egg production showed more than a twofold reduction when the complete TURFs scenario was compared against complete OAAs condition in both species. Individual size and density explained between 60% and 100% of the variability in potential egg production, suggesting the importance of the enhancement of both biological variables in TURFs in Chile. Potential egg production for both species in the northern part of the studied domain was higher due to the combined effect of (a) suitable habitat and (b) concentration of TURFs. Our results suggest that partially protected areas, such as TURFs can significantly enhance the production of propagules that could seed exploited areas. PMID:28481886

The influence of partial cutting on mountain pine beetle-caused tree mortality in Black Hills ponderosa pine stands

Treesearch

J.M. Schmid; S.A. Mata; R.R. Kessler; J.B. Popp

2007-01-01

Ponderosa pine stands were partially cut to various stocking levels at five locations, periodically surveyed, and remeasured during the 20 years after installation. Mean diameter generally increased 2 inches over the 20-year period on most partially cut plots and less than 2 inches on unmanaged controls. Average diameter growth for diameter classes in partially cut...

SU-E-I-25: Quantification of Coronary Artery Cross-Sectional Area in CT Angiography Using Integrated Density: A Simulation Study

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

Johnson, T; Ding, H; Lipinski, J

2015-06-15

Purpose: To develop a physics-based model for accurate quantification of the cross-sectional area (CSA) of coronary arteries in CT angiography by measuring the integrated density to account for the partial volume effect. Methods: In this technique the integrated density of the object as compared with its local background is measured to account for the partial volume effect. Normal vessels were simulated as circles with diameters in the range of 0.1–3mm. Diseased vessels were simulated as 2, 3, and 4mm diameter vessels with 10–90% area stenosis, created by inserting circular plaques. A simplified two material model was used with the lumenmore » as 8mg/ml Iodine and background as lipid. The contrast-to-noise ratio between lumen and background was approximately 26. Linear fits to the known CSA were calculated. The precision and accuracy of the measurement were quantified using the root-mean-square fit deviations (RMSD) and errors to the known CSA (RMSE). Results compared to manual segmentation of the vessel lumen. To assess the impact of random variations, coefficients of variation (CV) from 10 simulations for each vessel were computed to determine reliability. Measurements with CVs less than 10% were considered reliable. Results: For normal vessels, the precision and accuracy of the integrated density technique were 0.12mm{sup 2} and 0.28mm{sup 2}, respectively. The corresponding results for manual segmentation were 0.27mm{sup 2} and 0.43mm{sup 2}. For diseased vessels, the precision and accuracy of the integrated density technique were 0.14mm{sup 2} and 0.19mm{sup 2}. Corresponding results for manual segmentation were 0.42mm{sup 2} and 0.71mm{sup 2}. Reliable CSAs were obtained for normal vessels with diameters larger than 1 mm and for diseased vessels with area as low as 1.26mm2. Conclusion: The CSA based on integrated density showed improved precision and accuracy as compared with manual segmentation in simulation. These results indicate the potential of using integrated density to quantify CSA of coronary arteries in CT angiography.« less

Thermoplastic vulcanizate nanocomposites based on polypropylene/ethylene propylene diene terpolymer (PP/EPDM) prepared by reactive extrusion

NASA Astrophysics Data System (ADS)

Mirzadeh, Amin

For this work, different grades of polypropylene-g-maleic anhydride polymers were chosen to elucidate the effect of compatibilizer on the nanoclay dispersion level in thermoplastic phase. X-ray diffraction (XRD) patterns along with transmission electron microscopy (TEM) and scanning electron microscope (SEM) micrographs confirmed that prepared PP nanocomposites ranged from intercalated structure to a coexistence of intercalated tactoids and exfoliated layers namely “partially exfoliated” nanocomposite. Among various factors affecting the compatibilizer performance, it is shown that only the relaxation behaviour of compatibilizer correlates directly with the nanocomposites characterization results; higher relaxation times of the compatibilizer are associated with better dispersion of nanoclay. To study the co-continuity development of the nonreactive blends, EPDM and the mentioned PP nanocomposites at various compositions were melt blended using an internal mixer. Based on continuity measurements of TPEs and TPE nanocomposites for both thermoplastic and rubber phase, it is shown that the presence of nanoclay decreases the co-continuity composition range and alters its symmetrical feature. However, this effect is more pronounced in the intercalated nanocomposites than in partially exfoliated nanocomposites. It seems that better nanoclay dispersion limits the reduction of the thermoplastic phase continuity in a manner that the continuity index of the thermoplastic phase for partially exfoliated TPE nanocomposite prepared at high EPDM content (i.e. at 70 wt%) is greater than that of corresponding TPE without nanoclay. According to these results, it is possible to shift to higher EPDM content using partially exfoliated system before formation of matrix-dispersed particle structure which limits thermoplastic vulcanizate production. This should be mentioned that gamma irradiation was carried out in order to fix the EPDM morphology to estimate the continuity of PP using the solvent extraction and gravimetry technique. Additionally, the effect of continuity on rheological behaviour of TPE nanocomposites was investigated. The ultimate goal in this field is to maximize the rubber like behaviour by controlling the blend morphology and the level of crosslinking. Therefore, this study also covers the effects of nanoclay presence and its dispersion level on the crosslinking reaction of thermoplastic vulcanizate nanocomposites prepared by reactive extrusion. Here, the rubber phase was dynamically vulcanized using dimethylol phenolic resin or octylphenol-formaldehyde resin along with stannous chloride dihydrate as the catalyst. In the present study, the dynamic vulcanization of the prepared TPVs and corresponding nanocomposites are characterized using different criteria, such as gel content, viscosity and normalized storage modulus in the time sweep tests, nuclear magnetic resonance (NMR) signal line width, bound curative content and residual diene concentration. The combination of the above parameters appears to be sufficient to provide a clear description of the systems. The last part of the present study is devoted to find how the dispersion level of nanoclay and consequently the extent of crosslinking change the rubber like behaviour and the morphology of the prepared TPVs. Therefore, recently developed method named temperature scanning stress relaxation (TSSR) was used to estimate the rubber indices of TPVs and TPV nanocomposites. The mentioned method also successfully provided information about the extent of crosslinking reaction. It is shown that the rubber like behaviour of the blends containing 50wt% and 60wt% of EPDM in which morphological studies suggest the presence of the rubber droplets in vicinity of irregular shape rubber particles with a low level of interconnectivity, correlates with the rubber droplet size. Therefore, the nanoclay presence affects the rubber index values mainly through its effect on the size of the rubber droplets that controls the number of retraction points in the proposed buckling mechanism during the TSSR test. It should be mentioned that by increasing the EPDM content, the number of the droplet like domains decreases and more irregular shape rubber particles is formed. On the other hand, the direct relation between rubber index values and the crosslink density is observed only for those series of TPVs showing the fully developed extensive network between irregular shape rubber domains (blends containing 70wt% of EPDM). Hence, the nanoclay dispersion level influences the rubber like behaviour through its effect on the crosslink density. (Abstract shortened by UMI.).

Reduced Attention Allocation during Short Periods of Partially Automated Driving: An Event-Related Potentials Study

PubMed Central

Solís-Marcos, Ignacio; Galvao-Carmona, Alejandro; Kircher, Katja

2017-01-01

Research on partially automated driving has revealed relevant problems with driving performance, particularly when drivers’ intervention is required (e.g., take-over when automation fails). Mental fatigue has commonly been proposed to explain these effects after prolonged automated drives. However, performance problems have also been reported after just a few minutes of automated driving, indicating that other factors may also be involved. We hypothesize that, besides mental fatigue, an underload effect of partial automation may also affect driver attention. In this study, such potential effect was investigated during short periods of partially automated and manual driving and at different speeds. Subjective measures of mental demand and vigilance and performance to a secondary task (an auditory oddball task) were used to assess driver attention. Additionally, modulations of some specific attention-related event-related potentials (ERPs, N1 and P3 components) were investigated. The mental fatigue effects associated with the time on task were also evaluated by using the same measurements. Twenty participants drove in a fixed-base simulator while performing an auditory oddball task that elicited the ERPs. Six conditions were presented (5–6 min each) combining three speed levels (low, comfortable and high) and two automation levels (manual and partially automated). The results showed that, when driving partially automated, scores in subjective mental demand and P3 amplitudes were lower than in the manual conditions. Similarly, P3 amplitude and self-reported vigilance levels decreased with the time on task. Based on previous studies, these findings might reflect a reduction in drivers’ attention resource allocation, presumably due to the underload effects of partial automation and to the mental fatigue associated with the time on task. Particularly, such underload effects on attention could explain the performance decrements after short periods of automated driving reported in other studies. However, further studies are needed to investigate this relationship in partial automation and in other automation levels. PMID:29163112

[Correlation of retinol binding protein 4 with 
metabolic indexes of glucose and 
lipid, bile cholesterol saturation index].

PubMed

Wang, Wen; Li, Nianfeng

2015-06-01

To measure retinol binding protein 4 (RBP4) levels in serum and bile and to analyze their relationship with insulin resistance, dyslipidemia or cholesterol saturation index (CSI).
 A total of 60 patients with gallstone were divided into a diabetes group (n=30) and a control group (n=30). The concentrations of RBP4 in serum and bile were detected by enzyme-linked immunosorbent assay (ELISA). Enzyme colorimetric method was used to measure the concentration of biliary cholesterol, bile acid and phospholipid. Biliary CSI was calculated by Carey table. Partial correlation and multiple linear regression analysis were used to evaluate the correlation between the RBP4 levels in serum or bile and the above indexes.
 The RBP4 concentrations in serum and bile in the diabetes group were significantly elevated compared with those in the control group (both P<0.01). There was no significant difference in the serum total bile acid (TBA), serum triglyceride (TG), serum high-density lipoprotein (HDL), bile TBA, bile total cholesterol (TC) , bile phospholipids and bile CSI between the 2 groups (all P>0.05); but the serum TC, low density lipoprotein (LDL), fasting blood glucose (FBG), fasting insulin (FINS), and homeostasis model assessment for insulin resistance (HOMA-IR) in the diabetes group were significantly increased compared to those in the control group (all P<0.05). The partial correlation analysis, which was adjusted by age, showed that the bile RBP4 was positively correlated with body mass index (BMI), waist circumference (WC), FINS, FBG, TC, LDL and HOMA-IR (r=0.283, 0.405, 0.685, 0.667, 0.553, 0.424 and 0.735, respectively), and the serum RBP4 was also positively correlated with the WC, FINS, FBG, TC, LDL and HOMA-IR (r=0.317, 0.734, 0.609, 0.528, 0.386 and 0.751, respectively). Stepwise multivariate linear regression analysis suggested that the HOMA-IR, BMI and WC were independently correlated with the level of bile RBP4 (multiple regression equation: Ybile RBP4=2.372XHOMA-IR+0.420XBMI+0.178XWC-26.813), and the serum RBP4 level was correlated with the HOMA-IR and WC independently (multiple regression equation: Yserum RBP4=2.832XHOMA-IR +0.235XWC-20.128). Multiple regression equations showed that HOMA-IR was the strongest correlation factor with RBP4.
 RBP4 concentrations in serum and bile in the diabetes group are significantly higher than those in the control group. HOMA-IR, BMI and WC are independently correlated with the level of bile RBP4. HOMA-IR and WC are independently correlated with the serum RBP4 level. HOMA-IR is the strongest correlation factor with RBP4. RBP4 might play an important role in the course of gallstone formation in Type 2 diabetes mellitus.

Apolipoprotein E polymorphism and low density lipoprotein (LDL) oxidation in patients with dementia.

PubMed

Wehr, Hanna; Bednarska-Makaruk, Małgorzata; Graban, Ałła; Kunicki, Paweł K; Lojkowska, Wanda; Rodo, Maria; Ryglewicz, Danuta

2003-01-01

In patients with dementia, 29 diagnosed as probably suffering from Alzheimer's disease and 46 subjects with dementia of vascular origin, and in 41 non demented control subjects LDL oxidation in vitro was compared in carriers of various apolipoprotein E alleles. Restriction isotyping was performed by gene amplification and cleavage with Hhal, LDL oxidation was investigated by determination of conjugated dienes and vitamin E (alpha tocopherol) plasma level was measured by HPLC. In subjects with dementia oxidation of LDL was shown to be higher in carriers of epsilon4 allele as compared with non-carriers of this allele. It was especially observed in the propagation phase, which illustrates oxidation intensity after the exhaustion of the antioxidant reserve in LDL. Vitamin E level did not show differences between carriers of different alleles. It is concluded that the differences in oxidation susceptibility of LDL between demented subjects possessing particular apolipoprotein E forms can result partially from differing antioxidant properties of apolipoprotein E isoforms and, in a substantial degree, from the size and quality of LDL.

Observation of Multi-TeV Gamma Rays from the Crab Nebula using the Tibet Air Shower Array.

PubMed

Amenomori; Ayabe; Cao; Danzengluobu; Ding; Feng; Fu; Guo; He; Hibino; Hotta; Huang; Huo; Izu; Jia; Kajino; Kasahara; Katayose; Labaciren; Li; Lu; Lu; Luo; Meng; Mizutani; Mu; Nanjo; Nishizawa; Ohnishi; Ohta; Ouchi; Ren; Saito; Sakata; Sasaki; Shi; Shibata; Shiomi; Shirai; Sugimoto; Taira; Tan; Tateyama; Torii; Utsugi; Wang; Wang; Xu; Yamamoto; Yu; Yuan; Yuda; Zhang; Zhang; Zhang; Zhang; Zhang; Zhaxisangzhu; Zhaxiciren; Zhou; Collaboration)

1999-11-10

The Tibet experiment, operating at Yangbajing (4300 m above sea level), is the lowest energy air shower array, and the new high-density array constructed in 1996 is sensitive to gamma-ray air showers at energies as low as 3 TeV. With this new array, the Crab Nebula was observed in multi-TeV gamma-rays and a signal was detected at the 5.5 sigma level. We also obtained the energy spectrum of gamma-rays in the energy region above 3 TeV which partially overlaps those observed with imaging atmospheric Cerenkov telescopes. The Crab spectrum observed in this energy region can be represented by the power-law fit dJ&parl0;E&parr0;&solm0;dE=&parl0;4.61+/-0.90&parr0;x10-12&parl0;E&solm0;3 TeV&parr0;-2.62+/-0.17 cm-2 s-1 TeV-1. This is the first observation of gamma-ray signals from point sources with a conventional air shower array using scintillation detectors.

A united event grand canonical Monte Carlo study of partially doped polyaniline

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

Byshkin, M. S., E-mail: mbyshkin@unisa.it, E-mail: gmilano@unisa.it; Correa, A.; Buonocore, F.

2013-12-28

A Grand Canonical Monte Carlo scheme, based on united events combining protonation/deprotonation and insertion/deletion of HCl molecules is proposed for the generation of polyaniline structures at intermediate doping levels between 0% (PANI EB) and 100% (PANI ES). A procedure based on this scheme and subsequent structure relaxations using molecular dynamics is described and validated. Using the proposed scheme and the corresponding procedure, atomistic models of amorphous PANI-HCl structures were generated and studied at different doping levels. Density, structure factors, and solubility parameters were calculated. Their values agree well with available experimental data. The interactions of HCl with PANI have beenmore » studied and distribution of their energies has been analyzed. The procedure has also been extended to the generation of PANI models including adsorbed water and the effect of inclusion of water molecules on PANI properties has also been modeled and discussed. The protocol described here is general and the proposed United Event Grand Canonical Monte Carlo scheme can be easily extended to similar polymeric materials used in gas sensing and to other systems involving adsorption and chemical reactions steps.« less

Tracking the evolution of crossmodal plasticity and visual functions before and after sight restoration

PubMed Central

Dormal, Giulia; Lepore, Franco; Harissi-Dagher, Mona; Albouy, Geneviève; Bertone, Armando; Rossion, Bruno

2014-01-01

Visual deprivation leads to massive reorganization in both the structure and function of the occipital cortex, raising crucial challenges for sight restoration. We tracked the behavioral, structural, and neurofunctional changes occurring in an early and severely visually impaired patient before and 1.5 and 7 mo after sight restoration with magnetic resonance imaging. Robust presurgical auditory responses were found in occipital cortex despite residual preoperative vision. In primary visual cortex, crossmodal auditory responses overlapped with visual responses and remained elevated even 7 mo after surgery. However, these crossmodal responses decreased in extrastriate occipital regions after surgery, together with improved behavioral vision and with increases in both gray matter density and neural activation in low-level visual regions. Selective responses in high-level visual regions involved in motion and face processing were observable even before surgery and did not evolve after surgery. Taken together, these findings demonstrate that structural and functional reorganization of occipital regions are present in an individual with a long-standing history of severe visual impairment and that such reorganizations can be partially reversed by visual restoration in adulthood. PMID:25520432