The Prognostic Value of Tumor-Infiltrating Neutrophils in Gastric Adenocarcinoma after Resection

PubMed Central

Wang, Wei; Chen, Ju-gao; Wu, Yan-heng; Lv, Lin; Li, Jian-jun; Chen, Yi-bing; Wang, Dan-dan; Pan, Qiu-zhong; Li, Xiao-dong; Xia, Jian-chuan

2012-01-01

Background Several pieces of evidence indicate that tumor-infiltrating neutrophils (TINs) are correlated to tumor progression. In the current study, we explore the relationship between TINs and clinicopathological features of gastric adenocarcinoma patients. Furthermore, we investigated the prognostic value of TINs. Patients and Methods The study was comprised of two groups, training group (115 patients) and test group (97 patients). Biomarkers (intratumoral CD15+ neutrophils) were assessed by immunohistochemistry. The relationship between clinicopathological features and patient outcome were evaluated using Cox regression and Kaplan-Meier analysis. Results Immunohistochemical detection showed that the tumor-infiltrating neutrophils (TINs) in the training group ranged from 0.00–115.70 cells/high-power microscopic field (HPF) and the median number was 21.60 cells/HPF. Based on the median number, the patients were divided into high and low TINs groups. Chi-square test analysis revealed that the density of CD15+ TINs was positively associated with lymph node metastasis (p = 0.024), distance metastasis (p = 0.004) and UICC (International Union Against Cancer) staging (p = 0.028). Kaplan-Meier analysis showed that patients with a lower density of TINs had a better prognosis than patients with a higher density of TINs (p = 0.002). Multivariate Cox's analysis showed that the density of CD15+ TINs was an independent prognostic factor for overall survival of gastric adenocarcinoma patients. Using another 97 patients as a test group and basing on the median number of TINs (21.60 cells/HPF) coming from the training group, Kaplan-Meier analysis also showed that patients with a lower density of TINs had a better prognosis than patients with a higher density of TINs (p = 0.032). The results verify that the number of CD15+ TINs can predict the survival of gastric adenocarcinoma surgical patients. Conclusions The presence of CD15+ TINs is an independent and unfavorable factor in the prognosis of gastric adenocarcinoma patients. Targeting CD15+ TINs may be a potential intervenient therapy in the future. PMID:22442706

Effect of the target power density on high-power impulse magnetron sputtering of copper

NASA Astrophysics Data System (ADS)

Kozák, Tomáš

2012-04-01

We present a model analysis of high-power impulse magnetron sputtering of copper. We use a non-stationary global model based on the particle and energy conservation equations in two zones (the high density plasma ring above the target racetrack and the bulk plasma region), which makes it possible to calculate time evolutions of the averaged process gas and target material neutral and ion densities, as well as the fluxes of these particles to the target and substrate during a pulse period. We study the effect of the increasing target power density under conditions corresponding to a real experimental system. The calculated target current waveforms show a long steady state and are in good agreement with the experimental results. For an increasing target power density, an analysis of the particle densities shows a gradual transition to a metal dominated discharge plasma with an increasing degree of ionization of the depositing flux. The average fraction of target material ions in the total ion flux onto the substrate is more than 90% for average target power densities higher than 500 W cm-2 in a pulse. The average ionized fraction of target material atoms in the flux onto the substrate reaches 80% for a maximum average target power density of 3 kW cm-2 in a pulse.

The effect of activation agent on surface morphology, density and porosity of palm shell and coconut shell activated carbon

NASA Astrophysics Data System (ADS)

Leman, A. M.; Zakaria, S.; Salleh, M. N. M.; Sunar, N. M.; Feriyanto, D.; Nazri, A. A.

2017-09-01

Activated carbon (AC) has one of the promising alternative technology for filtration and adsorption process. It inexpensive material because the sources is abundant especially in Malaysia. Main purpose of this project is to develop AC by chemical activation process to improve adsorption capacity by improving porosity of AC. AC developed via carbonization using designed burner at temperature of 650°C to 850 °C and activated by Potassium Hydroxide (KOH) in 12 hour and then dried at temperature of 300°C. Characterization and analysis is conducted by Scanning Electron Microscopy (SEM) for surface morphology analysis, Energy Dispersive Spectroscopy (EDS) for composition analysis, density and porosity analysis. Results shows that uneven surface has been observed both of AC and non-AC and also AC shows higher porosity as compared to non-AC materials. Density value of raw material has lower than AC up to 11.67% and 47.54% and porosity of raw material has higher than AC up to 31.45% and 45.69% for palm shell and coconut shell AC. It can be concluded that lower density represent higher porosity of material and higher porosity indicated higher adsorption capacity as well.

LEDGF/p75 interacts with mRNA splicing factors and targets HIV-1 integration to highly spliced genes

PubMed Central

Singh, Parmit Kumar; Plumb, Matthew R.; Ferris, Andrea L.; Iben, James R.; Wu, Xiaolin; Fadel, Hind J.; Luke, Brian T.; Esnault, Caroline; Poeschla, Eric M.; Hughes, Stephen H.; Kvaratskhelia, Mamuka; Levin, Henry L.

2015-01-01

The host chromatin-binding factor LEDGF/p75 interacts with HIV-1 integrase and directs integration to active transcription units. To understand how LEDGF/p75 recognizes transcription units, we sequenced 1 million HIV-1 integration sites isolated from cultured HEK293T cells. Analysis of integration sites showed that cancer genes were preferentially targeted, raising concerns about using lentivirus vectors for gene therapy. Additional analysis led to the discovery that introns and alternative splicing contributed significantly to integration site selection. These correlations were independent of transcription levels, size of transcription units, and length of the introns. Multivariate analysis with five parameters previously found to predict integration sites showed that intron density is the strongest predictor of integration density in transcription units. Analysis of previously published HIV-1 integration site data showed that integration density in transcription units in mouse embryonic fibroblasts also correlated strongly with intron number, and this correlation was absent in cells lacking LEDGF. Affinity purification showed that LEDGF/p75 is associated with a number of splicing factors, and RNA sequencing (RNA-seq) analysis of HEK293T cells lacking LEDGF/p75 or the LEDGF/p75 integrase-binding domain (IBD) showed that LEDGF/p75 contributes to splicing patterns in half of the transcription units that have alternative isoforms. Thus, LEDGF/p75 interacts with splicing factors, contributes to exon choice, and directs HIV-1 integration to transcription units that are highly spliced. PMID:26545813

Optimum element density studies for finite-element thermal analysis of hypersonic aircraft structures

NASA Technical Reports Server (NTRS)

Ko, William L.; Olona, Timothy; Muramoto, Kyle M.

1990-01-01

Different finite element models previously set up for thermal analysis of the space shuttle orbiter structure are discussed and their shortcomings identified. Element density criteria are established for the finite element thermal modelings of space shuttle orbiter-type large, hypersonic aircraft structures. These criteria are based on rigorous studies on solution accuracies using different finite element models having different element densities set up for one cell of the orbiter wing. Also, a method for optimization of the transient thermal analysis computer central processing unit (CPU) time is discussed. Based on the newly established element density criteria, the orbiter wing midspan segment was modeled for the examination of thermal analysis solution accuracies and the extent of computation CPU time requirements. The results showed that the distributions of the structural temperatures and the thermal stresses obtained from this wing segment model were satisfactory and the computation CPU time was at the acceptable level. The studies offered the hope that modeling the large, hypersonic aircraft structures using high-density elements for transient thermal analysis is possible if a CPU optimization technique was used.

Thin layer asphaltic concrete density measuring using nuclear gages.

DOT National Transportation Integrated Search

1989-03-01

A Troxler 4640 thin layer nuclear gage was evaluated under field conditions to determine if it would provide improved accuracy of density measurements on asphalt overlays of 1-3/4 and 2 inches in thickness. Statistical analysis shows slightly improve...

Measurement of neoclassically predicted edge current density at ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Dunne, M. G.; McCarthy, P. J.; Wolfrum, E.; Fischer, R.; Giannone, L.; Burckhart, A.; the ASDEX Upgrade Team

2012-12-01

Experimental confirmation of neoclassically predicted edge current density in an ELMy H-mode plasma is presented. Current density analysis using the CLISTE equilibrium code is outlined and the rationale for accuracy of the reconstructions is explained. Sample profiles and time traces from analysis of data at ASDEX Upgrade are presented. A high time resolution is possible due to the use of an ELM-synchronization technique. Additionally, the flux-surface-averaged current density is calculated using a neoclassical approach. Results from these two separate methods are then compared and are found to validate the theoretical formula. Finally, several discharges are compared as part of a fuelling study, showing that the size and width of the edge current density peak at the low-field side can be explained by the electron density and temperature drives and their respective collisionality modifications.

Effect of Primary-Ion Current Density on Charge Compensation in SIMS Analysis of a Quartz Glass

NASA Astrophysics Data System (ADS)

Inoue, Kazuyuki; Isogai, Akio

1988-05-01

In secondary ion mass spectrometry (SIMS) analysis of a quartz glass by means of negative ion bombardment, the effect of the negative ion current density (Ji) has been investigated. The results show that under lower Ji (<20 μA/cm2), time is required to compensate for the surface charge and the time is inversely proportional to Ji.

Interplanetary density models as inferred from solar Type III bursts

NASA Astrophysics Data System (ADS)

Oppeneiger, Lucas; Boudjada, Mohammed Y.; Lammer, Helmut; Lichtenegger, Herbert

2016-04-01

We report on the density models derived from spectral features of solar Type III bursts. They are generated by beams of electrons travelling outward from the Sun along open magnetic field lines. Electrons generate Langmuir waves at the plasma frequency along their ray paths through the corona and the interplanetary medium. A large frequency band is covered by the Type III bursts from several MHz down to few kHz. In this analysis, we consider the previous empirical density models proposed to describe the electron density in the interplanetary medium. We show that those models are mainly based on the analysis of Type III bursts generated in the interplanetary medium and observed by satellites (e.g. RAE, HELIOS, VOYAGER, ULYSSES,WIND). Those models are confronted to stereoscopic observations of Type III bursts recorded by WIND, ULYSSES and CASSINI spacecraft. We discuss the spatial evolution of the electron beam along the interplanetary medium where the trajectory is an Archimedean spiral. We show that the electron beams and the source locations are depending on the choose of the empirical density models.

Quantitative contribution of molecular orbitals to hydrogen bonding in a water dimer: Electron density projected integral (EDPI) analysis

NASA Astrophysics Data System (ADS)

Zhang, Zhiyuan; Jiang, Wanrun; Wang, Bo; Wang, Zhigang

2017-06-01

We introduce the orbital-resolved electron density projected integral (EDPI) along the H-bond in the real space to quantitatively investigate the specific contribution from the molecular orbitals (MOs) aspect in (H2O)2. Calculation results show that, the electronic occupied orbital (HOMO-4) of (H2O)2 accounts for about surprisingly 40% of the electron density at the bond critical point. Moreover, the electronic density difference analysis visualizes the electron accumulating effect of the orbital interaction within the H-bond between water molecules, supporting its covalent-like character. Our work expands the understanding of H-bond with specific contributions from certain MOs.

On the characterization of inhomogeneity of the density distribution in supercritical fluids via molecular dynamics simulation and data mining analysis.

PubMed

Idrissi, Abdenacer; Vyalov, Ivan; Georgi, Nikolaj; Kiselev, Michael

2013-10-10

We combined molecular dynamics simulation and DBSCAN algorithm (Density Based Spatial Clustering of Application with Noise) in order to characterize the local density inhomogeneity distribution in supercritical fluids. The DBSCAN is an algorithm that is capable of finding arbitrarily shaped density domains, where domains are defined as dense regions separated by low-density regions. The inhomogeneity of density domain distributions of Ar system in sub- and supercritical conditions along the 50 bar isobar is associated with the occurrence of a maximum in the fluctuation of number of particles of the density domains. This maximum coincides with the temperature, Tα, at which the thermal expansion occurs. Furthermore, using Voronoi polyhedral analysis, we characterized the structure of the density domains. The results show that with increasing temperature below Tα, the increase of the inhomogeneity is mainly associated with the density fluctuation of the border particles of the density domains, while with increasing temperature above Tα, the decrease of the inhomogeneity is associated with the core particles.

Ultrasonic density measurement cell design and simulation of non-ideal effects.

PubMed

Higuti, Ricardo Tokio; Buiochi, Flávio; Adamowski, Júlio Cezar; de Espinosa, Francisco Montero

2006-07-01

This paper presents a theoretical analysis of a density measurement cell using an unidimensional model composed by acoustic and electroacoustic transmission lines in order to simulate non-ideal effects. The model is implemented using matrix operations, and is used to design the cell considering its geometry, materials used in sensor assembly, range of liquid sample properties and signal analysis techniques. The sensor performance in non-ideal conditions is studied, considering the thicknesses of adhesive and metallization layers, and the effect of residue of liquid sample which can impregnate on the sample chamber surfaces. These layers are taken into account in the model, and their effects are compensated to reduce the error on density measurement. The results show the contribution of residue layer thickness to density error and its behavior when two signal analysis methods are used.

The influence of landscape features on road development in a loess region, China.

PubMed

Bi, Xiaoli; Wang, Hui; Zhou, Rui

2011-10-01

Many ecologists focus on the effects of roads on landscapes, yet few consider how landscapes affect road systems. In this study, therefore, we quantitatively evaluated how land cover, topography, and building density affected the length density, node density, spatial pattern, and location of roads in Dongzhi Yuan, a typical loess region in China. Landscape factors and roads were mapped using images from SPOT satellite (Système Probatoire d'Observation de la Terre), initiated by the French space agency and a digital elevation model (DEM). Detrended canonical correspondence analysis (DCCA), a useful ordination technique to explain species-environment relations in community ecology, was applied to evaluate the ways in which landscapes may influence roads. The results showed that both farmland area and building density were positively correlated with road variables, whereas gully density and the coefficient of variation (CV of DEM) showed negative correlations. The CV of DEM, farmland area, grassland area, and building density explained variation in node density, length density, and the spatial pattern of roads, whereas gully density and building density explained variation in variables representing road location. In addition, node density, rather than length density, was the primary road variable affected by landscape variables. The results showed that the DCCA was effective in explaining road-landscape relations. Understanding these relations can provide information for landscape managers and transportation planners.

[Estimation of Hunan forest carbon density based on spectral mixture analysis of MODIS data].

PubMed

Yan, En-ping; Lin, Hui; Wang, Guang-xing; Chen, Zhen-xiong

2015-11-01

With the fast development of remote sensing technology, combining forest inventory sample plot data and remotely sensed images has become a widely used method to map forest carbon density. However, the existence of mixed pixels often impedes the improvement of forest carbon density mapping, especially when low spatial resolution images such as MODIS are used. In this study, MODIS images and national forest inventory sample plot data were used to conduct the study of estimation for forest carbon density. Linear spectral mixture analysis with and without constraint, and nonlinear spectral mixture analysis were compared to derive the fractions of different land use and land cover (LULC) types. Then sequential Gaussian co-simulation algorithm with and without the fraction images from spectral mixture analyses were employed to estimate forest carbon density of Hunan Province. Results showed that 1) Linear spectral mixture analysis with constraint, leading to a mean RMSE of 0.002, more accurately estimated the fractions of LULC types than linear spectral and nonlinear spectral mixture analyses; 2) Integrating spectral mixture analysis model and sequential Gaussian co-simulation algorithm increased the estimation accuracy of forest carbon density to 81.5% from 74.1%, and decreased the RMSE to 5.18 from 7.26; and 3) The mean value of forest carbon density for the province was 30.06 t · hm(-2), ranging from 0.00 to 67.35 t · hm(-2). This implied that the spectral mixture analysis provided a great potential to increase the estimation accuracy of forest carbon density on regional and global level.

Responses of meiofauna and nematode communities to crude oil contamination in a laboratory microcosm experiment

NASA Astrophysics Data System (ADS)

Kang, Teawook; Oh, Je Hyeok; Hong, Jae-Sang; Kim, Dongsung

2016-09-01

We examined the effects of crude oil contamination on community assemblages of meiofauna and nematodes after exposure to total petroleum hydrocarbons in the laboratory. We administered a seawater solution that had been contaminated with total petroleum hydrocarbons to seven treatment groups at different concentrations, while the control group received uncontaminated filtered seawater. The average density of total meiofauna in the experimental microcosms diluted with 0.5%, 1%, 2%, and 4% contaminated seawater was higher than the density in the control. The average density of total meiofauna in the 8%, 15%, and 20% microcosms was lower than the density in the control. The density of nematodes was similar to that of the total meiofauna. Cluster analysis divided the microcosms into group 1 (control, 0.5%, 1%, 2%, and 4% microcosms) and group 2 (8%, 15%, and 20% microcosms). However, SIMPROF analysis showed no significant difference between the two groups ( p > 0.05). Bolbolaimus spp. (37.1%) were dominant among the nematodes. Cluster analysis showed similar results for nematode and meiofaunal communities. The total meiofaunal density, nematode density, and number of Bolbolaimus spp. individuals were significantly negatively associated with the concentration of total petroleum hydrocarbons (Spearman correlation coefficients, p < 0.05). Within the nematodes, epistrate feeders (group 2A: 46%) were the most abundant trophic group. Among the treatment groups, the abundance of group 2A increased in low-concentration microcosms and decreased in high-concentration microcosms. Thus, our findings provide information on the effects of oil pollution on meiofauna in the intertidal zones of sandy beaches.

Effects of urbanization on benthic macroinvertebrate communities in streams, Anchorage, Alaska

USGS Publications Warehouse

Ourso, Robert T.

2001-01-01

The effect of urbanization on stream macroinvertebrate communities was examined by using data gathered during a 1999 reconnaissance of 14 sites in the Municipality of Anchorage, Alaska. Data collected included macroinvertebrate abundance, water chemistry, and trace elements in bed sediments. Macroinvertebrate relative-abundance data were edited and used in metric and index calculations. Population density was used as a surrogate for urbanization. Cluster analysis (unweighted-paired-grouping method) using arithmetic means of macroinvertebrate presence-absence data showed a well-defined separation between urbanized and nonurbanized sites as well as extracted sites that did not cleanly fall into either category. Water quality in Anchorage generally declined with increasing urbanization (population density). Of 59 variables examined, 31 correlated with urbanization. Local regression analysis extracted 11 variables that showed a significant impairment threshold response and 6 that showed a significant linear response. Significant biological variables for determining the impairment threshold in this study were the Margalef diversity index, Ephemeroptera-Plecoptera-Trichoptera taxa richness, and total taxa richness. Significant thresholds were observed in the water-chemistry variables conductivity, dissolved organic carbon, potassium, and total dissolved solids. Significant thresholds in trace elements in bed sediments included arsenic, iron, manganese, and lead. Results suggest that sites in Anchorage that have ratios of population density to road density greater than 70, storm-drain densities greater than 0.45 miles per square mile, road densities greater than 4 miles per square mile, or population densities greater than 125-150 persons per square mile may require further monitoring to determine if the stream has become impaired. This population density is far less than the 1,000 persons per square mile used by the U.S. Census Bureau to define an urban area.

Comparison of direct and flow integration based charge density population analyses.

PubMed

Francisco, E; Martín Pendas, A; Blanco, M A; Costales, A

2007-12-06

Different exhaustive and fuzzy partitions of the molecular electron density (rho) into atomic densities (rho(A)) are used to compute the atomic charges (Q(A)) of a representative set of molecules. The Q(A)'s derived from a direct integration of rho(A) are compared to those obtained from integrating the deformation density rho(def) = rho - rho(0) within each atomic domain. Our analysis shows that the latter methods tend to give Q(A)'s similar to those of the (arbitrary) reference atomic densities rho(A)(0) used in the definition of the promolecular density, rho(0) = SigmaArho(A)(0). Moreover, we show that the basis set independence of these charges is a sign not of their intrinsic quality, as commonly stated, but of the practical insensitivity on the basis set of the atomic domains that are employed in this type of methods.

Bivariate genome-wide association meta-analysis of pediatric musculoskeletal traits reveals pleiotropic effects at the SREBF1/TOM1L2 locus.

PubMed

Medina-Gomez, Carolina; Kemp, John P; Dimou, Niki L; Kreiner, Eskil; Chesi, Alessandra; Zemel, Babette S; Bønnelykke, Klaus; Boer, Cindy G; Ahluwalia, Tarunveer S; Bisgaard, Hans; Evangelou, Evangelos; Heppe, Denise H M; Bonewald, Lynda F; Gorski, Jeffrey P; Ghanbari, Mohsen; Demissie, Serkalem; Duque, Gustavo; Maurano, Matthew T; Kiel, Douglas P; Hsu, Yi-Hsiang; C J van der Eerden, Bram; Ackert-Bicknell, Cheryl; Reppe, Sjur; Gautvik, Kaare M; Raastad, Truls; Karasik, David; van de Peppel, Jeroen; Jaddoe, Vincent W V; Uitterlinden, André G; Tobias, Jonathan H; Grant, Struan F A; Bagos, Pantelis G; Evans, David M; Rivadeneira, Fernando

2017-07-25

Bone mineral density is known to be a heritable, polygenic trait whereas genetic variants contributing to lean mass variation remain largely unknown. We estimated the shared SNP heritability and performed a bivariate GWAS meta-analysis of total-body lean mass (TB-LM) and total-body less head bone mineral density (TBLH-BMD) regions in 10,414 children. The estimated SNP heritability is 43% (95% CI: 34-52%) for TBLH-BMD, and 39% (95% CI: 30-48%) for TB-LM, with a shared genetic component of 43% (95% CI: 29-56%). We identify variants with pleiotropic effects in eight loci, including seven established bone mineral density loci: WNT4, GALNT3, MEPE, CPED1/WNT16, TNFSF11, RIN3, and PPP6R3/LRP5. Variants in the TOM1L2/SREBF1 locus exert opposing effects TB-LM and TBLH-BMD, and have a stronger association with the former trait. We show that SREBF1 is expressed in murine and human osteoblasts, as well as in human muscle tissue. This is the first bivariate GWAS meta-analysis to demonstrate genetic factors with pleiotropic effects on bone mineral density and lean mass.Bone mineral density and lean skeletal mass are heritable traits. Here, Medina-Gomez and colleagues perform bivariate GWAS analyses of total body lean mass and bone mass density in children, and show genetic loci with pleiotropic effects on both traits.

Factors Affecting Choroidal Vascular Density in Normal Eyes: Quantification Using En Face Swept-Source Optical Coherence Tomography.

PubMed

Fujiwara, Atsushi; Morizane, Yuki; Hosokawa, Mio; Kimura, Shuhei; Kumase, Fumiaki; Shiode, Yusuke; Doi, Shinichiro; Hirano, Masayuki; Toshima, Shinji; Hosogi, Mika; Shiraga, Fumio

2016-10-01

To quantify the vascular density of the choroid of normal eyes and to identify the influencing factors using en face images obtained with swept-source optical coherence tomography (SS OCT). Prospective cross-sectional study. One hundred and sixty-three eyes of 163 healthy volunteers (83 female; mean age 42.2 ± 22.6 years) with a corrected visual acuity of ≥1.0 were investigated. En face SS OCT images of the choroid were used for quantitative assessment of the vascular density in the large choroid vessel layer. Relationships between vascular density of the choroid and age, sex, refractive error (RE), axial length (AL), and subfoveal choroidal thickness (SCT) were also investigated. There was a significant negative relationship between vascular density of the choroid and subject age (P < .001). Analysis according to age showed a significant correlation in the group aged >30 years (P < .001), but not in the group aged ≤30 years (P = .225). SCT had a significant positive relationship with vascular density of the choroid (P < .001). However, a significant correlation was not observed between sex, RE, or AL and vascular density of the choroid (P = .981, P = .292, and P = .216, respectively). Multivariable regression analysis with vascular density of the choroid as the dependent variable and age, sex, RE, AL, and SCT as independent variables showed that age and SCT are important determinants of vascular density of the choroid (P < .001). Age and SCT affect vascular density of the choroid. Copyright © 2016 Elsevier Inc. All rights reserved.

Alternative definitions of the frozen energy in energy decomposition analysis of density functional theory calculations.

PubMed

Horn, Paul R; Head-Gordon, Martin

2016-02-28

In energy decomposition analysis (EDA) of intermolecular interactions calculated via density functional theory, the initial supersystem wavefunction defines the so-called "frozen energy" including contributions such as permanent electrostatics, steric repulsions, and dispersion. This work explores the consequences of the choices that must be made to define the frozen energy. The critical choice is whether the energy should be minimized subject to the constraint of fixed density. Numerical results for Ne2, (H2O)2, BH3-NH3, and ethane dissociation show that there can be a large energy lowering associated with constant density orbital relaxation. By far the most important contribution is constant density inter-fragment relaxation, corresponding to charge transfer (CT). This is unwanted in an EDA that attempts to separate CT effects, but it may be useful in other contexts such as force field development. An algorithm is presented for minimizing single determinant energies at constant density both with and without CT by employing a penalty function that approximately enforces the density constraint.

Comment on ‘Are physicists afraid of mathematics?’

NASA Astrophysics Data System (ADS)

Higginson, Andrew D.; Fawcett, Tim W.

2016-11-01

In 2012, we showed that the citation count for articles in ecology and evolutionary biology declines with increasing density of equations. Kollmer et al (2015 New J. Phys. 17 013036) claim this effect is an artefact of the manner in which we plotted the data. They also present citation data from Physical Review Letters and argue, based on graphs, that citation counts are unrelated to equation density. Here we show that both claims are misguided. We identified the effects in biology not by visual means, but using the most appropriate statistical analysis. Since Kollmer et al did not carry out any statistical analysis, they cannot draw reliable inferences about the citation patterns in physics. We show that when statistically analysed their data actually do provide evidence that in physics, as in biology, citation counts are lower for articles with a high density of equations. This indicates that a negative relationship between equation density and citations may extend across the breadth of the sciences, even those in which researchers are well accustomed to mathematical descriptions of natural phenomena. We restate our assessment that this is a genuine problem and discuss what we think should be done about it.

Effect of Cross-Linking on Free Volume Properties of PEG Based Thiol-Ene Networks

NASA Astrophysics Data System (ADS)

Ramakrishnan, Ramesh; Vasagar, Vivek; Nazarenko, Sergei

According to the Fox and Loshaek theory, in elastomeric networks, free volume decreases linearly with the cross-link density increase. The aim of this study is to show whether the poly(ethylene glycol) (PEG) based multicomponent thiol-ene elastomeric networks demonstrate this model behavior? Networks with a broad cross-link density range were prepared by changing the ratio of the trithiol crosslinker to PEG dithiol and then UV cured with PEG diene while maintaining 1:1 thiol:ene stoichiometry. Pressure-volume-temperature (PVT) data of the networks was generated from the high pressure dilatometry experiments which was fit using the Simha-Somcynsky Equation-of-State analysis to obtain the fractional free volume of the networks. Using Positron Annihilation Lifetime Spectroscopy (PALS) analysis, the average free volume hole size of the networks was also quantified. The fractional free volume and the average free volume hole size showed a linear change with the cross-link density confirming that the Fox and Loshaek theory can be applied to this multicomponent system. Gas diffusivities of the networks showed a good correlation with free volume. A free volume based model was developed to describe the gas diffusivity trends as a function of cross-link density.

Insulin-like growth factor-I (IGF-1), IGF-binding protein-3 (IGFBP-3) and mammographic features.

PubMed

Izzo, L; Meggiorini, M L; Nofroni, I; Pala, A; De Felice, C; Meloni, P; Simari, T; Izzo, S; Pugliese, F; Impara, L; Merlini, G; Di Cello, P; Cipolla, V; Forcione, A R; Paliotta, A; Domenici, L; Bolognese, A

2012-05-01

The IGF system has recently been shown to play an important role in the regulation of breast tumor cell proliferation. However, also breast density is currently considered as the strongest breast cancer risk factor. It is not yet clear whether these factors are interrelated and if and how they are influenced by menopausal status. The purpose of this study was to examine the possible effects of IGF-1 and IGFBP-3 and IGF-1/IGFBP-3 molar ratio on mammographic density stratified by menopausal status. A group of 341 Italian women were interviewed to collect the following data: family history of breast cancer, reproductive and menstrual factors, breast biopsies, previous administration of hormonal contraceptive therapy, hormone replacement therapy (HRT) in menopause and lifestyle information. A blood sample was drawn for determination of IGF-1, IGFBP-3 levels. IGF-1/ IGFBP-3 molar ratio was then calculated. On the basis of recent mammograms the women were divided into two groups: dense breast (DB) and non-dense breast (NDB). Student's t-test was employed to assess the association between breast density and plasma level of IGF-1, IGFBP-3 and molar ratio. To assess if this relationship was similar in subgroups of pre- and postmenopausal women, the study population was stratified by menopausal status and Student's t-test was performed. Finally, multivariate analysis was employed to evaluate if there were confounding factors that might influence the relationship between growth factors and breast density. The analysis of the relationship between mammographic density and plasma level of IGF-1, IGFBP-3 and IGF-1/ IGFBP-3 molar ratio showed that IGF-1 levels and molar ratio varied in the two groups resulting in higher mean values in the DB group (IGF-1: 109.6 versus 96.6 ng/ml; p= 0.001 and molar ratio 29.4 versus 25.5 ng/ml; p= 0.001) whereas IGFBP-3 showed similar values in both groups (DB and NDB). Analysis of plasma level of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 molar ratio compared to breast density after stratification of the study population by menopausal status (premenopausal and postmenopausal) showed that there was no association between the plasma of growth factors and breast density, neither in premenopausal nor in postmenopausal patients. Multivariate analysis showed that only nulliparity, premenopausal status and body mass index (BMI) are determinants of breast density. Our study provides a strong evidence of a crude association between breast density and plasma levels of IGF-1 and molar ratio. On the basis of our results, it is reasonable to assume that the role of IGF-1 and molar ratio in the pathogenesis of breast cancer might be mediated through mammographic density. IGF-1 and molar ratio might thus increase the risk of cancer by increasing mammographic density.

Shape information from a critical point analysis of calculated electron density maps: application to DNA-drug systems

NASA Astrophysics Data System (ADS)

Leherte, L.; Allen, F. H.; Vercauteren, D. P.

1995-04-01

A computational method is described for mapping the volume within the DNA double helix accessible to a groove-binding antibiotic, netropsin. Topological critical point analysis is used to locate maxima in electron density maps reconstructed from crystallographically determined atomic coordinates. The peaks obtained in this way are represented as ellipsoids with axes related to local curvature of the electron density function. Combining the ellipsoids produces a single electron density function which can be probed to estimate effective volumes of the interacting species. Close complementarity between host and ligand in this example shows the method to be a good representation of the electron density function at various resolutions; while at the atomic level the ellipsoid method gives results which are in close agreement with those from the conventional, spherical, van der Waals approach.

Shape information from a critical point analysis of calculated electron density maps: Application to DNA-drug systems

NASA Astrophysics Data System (ADS)

Leherte, Laurence; Allen, Frank H.

1994-06-01

A computational method is described for mapping the volume within the DNA double helix accessible to the groove-binding antibiotic netropsin. Topological critical point analysis is used to locate maxima in electron density maps reconstructed from crystallographically determined atomic coordinates. The peaks obtained in this way are represented as ellipsoids with axes related to local curvature of the electron density function. Combining the ellipsoids produces a single electron density function which can be probed to estimate effective volumes of the interacting species. Close complementarity between host and ligand in this example shows the method to give a good representation of the electron density function at various resolutions. At the atomic level, the ellipsoid method gives results which are in close agreement with those from the conventional spherical van der Waals approach.

UC/MALDI-MS analysis of HDL; evidence for density-dependent post-translational modifications

NASA Astrophysics Data System (ADS)

Johnson, Jeffery D.; Henriquez, Ronald R.; Tichy, Shane E.; Russell, David H.; McNeal, Catherine J.; Macfarlane, Ronald D.

2007-12-01

The purpose of this study is to determine whether the nature of the post-translational modifications of the major apolipoproteins of HDL is different for density-distinct subclasses. These subclasses were separated by ultracentrifugation using a novel density-forming solute to yield a high-resolution separation. The serum of two subjects, a control with a normolipidemic profile and a subject with diagnosed cardiovascular disease, was studied. Aliquots of three HDL subclasses were analyzed by MALDI and considerable differences were seen when comparing density-distinct subclasses and also when comparing the two subjects. A detailed analysis of the post-translational modification pattern of apoA-1 shows evidence of considerable protease activity, particularly in the more dense fractions. We conclude that part of the heterogeneity of the population of HDL particles is due to density-dependent protease activity.

Eddy current loss analysis of open-slot fault-tolerant permanent-magnet machines based on conformal mapping method

NASA Astrophysics Data System (ADS)

Ji, Jinghua; Luo, Jianhua; Lei, Qian; Bian, Fangfang

2017-05-01

This paper proposed an analytical method, based on conformal mapping (CM) method, for the accurate evaluation of magnetic field and eddy current (EC) loss in fault-tolerant permanent-magnet (FTPM) machines. The aim of modulation function, applied in CM method, is to change the open-slot structure into fully closed-slot structure, whose air-gap flux density is easy to calculate analytically. Therefore, with the help of Matlab Schwarz-Christoffel (SC) Toolbox, both the magnetic flux density and EC density of FTPM machine are obtained accurately. Finally, time-stepped transient finite-element method (FEM) is used to verify the theoretical analysis, showing that the proposed method is able to predict the magnetic flux density and EC loss precisely.

Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, 13C, 1H) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2-acetoxybenzoic acid by density functional methods

NASA Astrophysics Data System (ADS)

Bhavani, K.; Renuga, S.; Muthu, S.; Sankara narayanan, K.

2015-02-01

In this work, colorless crystals of 2-acetoxybenzoic acid were grown by slow evaporation method and the FT-IR and FT-Raman spectra of the sample were recorded in the region 4000-500 cm-1 and 4000-100 cm-1 respectively. Molecular structure is optimized with the help of density functional theory method (B3LYP) with 6-31+G(d,p), 6-311++G(d,p) basis sets. Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the σ∗ antibonding orbitals and E(2) energies confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis following the scaled quantum mechanical force field (SQMFF) methodology. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. Mulliken population analysis on atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule.

Characterizing Bonding Patterns in Diradicals and Triradicals by Density-Based Wave Function Analysis: A Uniform Approach.

PubMed

Orms, Natalie; Rehn, Dirk R; Dreuw, Andreas; Krylov, Anna I

2018-02-13

Density-based wave function analysis enables unambiguous comparisons of the electronic structure computed by different methods and removes ambiguity of orbital choices. We use this tool to investigate the performance of different spin-flip methods for several prototypical diradicals and triradicals. In contrast to previous calibration studies that focused on energy gaps between high- and low spin-states, we focus on the properties of the underlying wave functions, such as the number of effectively unpaired electrons. Comparison of different density functional and wave function theory results provides insight into the performance of the different methods when applied to strongly correlated systems such as polyradicals. We show that canonical molecular orbitals for species like large copper-containing diradicals fail to correctly represent the underlying electronic structure due to highly non-Koopmans character, while density-based analysis of the same wave function delivers a clear picture of the bonding pattern.

The influence of crowd density on the sound environment of commercial pedestrian streets.

PubMed

Meng, Qi; Kang, Jian

2015-04-01

Commercial pedestrian streets are very common in China and Europe, with many situated in historic or cultural centres. The environments of these streets are important, including their sound environments. The objective of this study is to explore the relationships between the crowd density and the sound environments of commercial pedestrian streets. On-site measurements were performed at the case study site in Harbin, China, and a questionnaire was administered. The sound pressure measurements showed that the crowd density has an insignificant effect on sound pressure below 0.05 persons/m2, whereas when the crowd density is greater than 0.05 persons/m2, the sound pressure increases with crowd density. The sound sources were analysed, showing that several typical sound sources, such as traffic noise, can be masked by the sounds resulting from dense crowds. The acoustic analysis showed that crowd densities outside the range of 0.10 to 0.25 persons/m2 exhibited lower acoustic comfort evaluation scores. In terms of audiovisual characteristics, the subjective loudness increases with greater crowd density, while the acoustic comfort decreases. The results for an indoor underground shopping street are also presented for comparison. Copyright © 2014 Elsevier B.V. All rights reserved.

Density-cluster NMA: A new protein decomposition technique for coarse-grained normal mode analysis.

PubMed

Demerdash, Omar N A; Mitchell, Julie C

2012-07-01

Normal mode analysis has emerged as a useful technique for investigating protein motions on long time scales. This is largely due to the advent of coarse-graining techniques, particularly Hooke's Law-based potentials and the rotational-translational blocking (RTB) method for reducing the size of the force-constant matrix, the Hessian. Here we present a new method for domain decomposition for use in RTB that is based on hierarchical clustering of atomic density gradients, which we call Density-Cluster RTB (DCRTB). The method reduces the number of degrees of freedom by 85-90% compared with the standard blocking approaches. We compared the normal modes from DCRTB against standard RTB using 1-4 residues in sequence in a single block, with good agreement between the two methods. We also show that Density-Cluster RTB and standard RTB perform well in capturing the experimentally determined direction of conformational change. Significantly, we report superior correlation of DCRTB with B-factors compared with 1-4 residue per block RTB. Finally, we show significant reduction in computational cost for Density-Cluster RTB that is nearly 100-fold for many examples. Copyright © 2012 Wiley Periodicals, Inc.

Prior-knowledge-based spectral mixture analysis for impervious surface mapping

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

Zhang, Jinshui; He, Chunyang; Zhou, Yuyu

2014-01-03

In this study, we developed a prior-knowledge-based spectral mixture analysis (PKSMA) to map impervious surfaces by using endmembers derived separately for high- and low-density urban regions. First, an urban area was categorized into high- and low-density urban areas, using a multi-step classification method. Next, in high-density urban areas that were assumed to have only vegetation and impervious surfaces (ISs), the Vegetation-Impervious model (V-I) was used in a spectral mixture analysis (SMA) with three endmembers: vegetation, high albedo, and low albedo. In low-density urban areas, the Vegetation-Impervious-Soil model (V-I-S) was used in an SMA analysis with four endmembers: high albedo, lowmore » albedo, soil, and vegetation. The fraction of IS with high and low albedo in each pixel was combined to produce the final IS map. The root mean-square error (RMSE) of the IS map produced using PKSMA was about 11.0%, compared to 14.52% using four-endmember SMA. Particularly in high-density urban areas, PKSMA (RMSE = 6.47%) showed better performance than four-endmember (15.91%). The results indicate that PKSMA can improve IS mapping compared to traditional SMA by using appropriately selected endmembers and is particularly strong in high-density urban areas.« less

The Effects of Prior Cold Work on the Shock Response of Copper

NASA Astrophysics Data System (ADS)

Millett, J. C. F.; Higgins, D. L.; Chapman, D. J.; Whiteman, G.; Jones, I. P.; Chiu, Y.-L.

2018-04-01

A series of experiments have been performed to probe the effects of dislocation density on the shock response of copper. The shear strength immediately behind the shock front has been measured using embedded manganin stress gauges, whilst the post shock microstructural and mechanical response has been monitored via one-dimensional recovery experiments. Material in the half hard (high dislocation density) condition was shown to have both a higher shear strength and higher rate of change of shear strength with impact stress than its annealed (low dislocation density) counterpart. Microstructural analysis showed a much higher dislocation density in the half hard material compared to the annealed after shock loading, whilst post shock mechanical examination showed a significant degree of hardening in the annealed state with reduced, but still significant amount in the half hard state, thus showing a correlation between temporally resolved stress gauge measurements and post shock microstructural and mechanical properties.

Structural and electronic properties of OsB2 : A hard metallic material

NASA Astrophysics Data System (ADS)

Chen, Z. Y.; Xiang, H. J.; Yang, Jinlong; Hou, J. G.; Zhu, Qingshi

2006-07-01

We calculate the structural and electronic properties of OsB2 using density functional theory with or without taking into account the spin-orbit (SO) interaction. Our results show that the bulk modulus with and without SO interactions are 364 and 365GPa , respectively, both are in good agreement with experiment (365-395GPa) . The evidence of covalent bonding of Os-B, which plays an important role to form a hard material, is indicated both in charge density, atoms in molecules analysis, and density of states analysis. The good metallicity and hardness of OsB2 might suggest its potential application as hard conductors.

Turbulence Statistics of a Buoyant Jet in a Stratified Environment

NASA Astrophysics Data System (ADS)

McCleney, Amy Brooke

Using non-intrusive optical diagnostics, turbulence statistics for a round, incompressible, buoyant, and vertical jet discharging freely into a stably linear stratified environment is studied and compared to a reference case of a neutrally buoyant jet in a uniform environment. This is part of a validation campaign for computational fluid dynamics (CFD). Buoyancy forces are known to significantly affect the jet evolution in a stratified environment. Despite their ubiquity in numerous natural and man-made flows, available data in these jets are limited, which constrain our understanding of the underlying physical processes. In particular, there is a dearth of velocity field data, which makes it challenging to validate numerical codes, currently used for modeling these important flows. Herein, jet near- and far-field behaviors are obtained with a combination of planar laser induced fluorescence (PLIF) and multi-scale time-resolved particle image velocimetry (TR-PIV) for Reynolds number up to 20,000. Deploying non-intrusive optical diagnostics in a variable density environment is challenging in liquids. The refractive index is strongly affected by the density, which introduces optical aberrations and occlusions that prevent the resolution of the flow. One solution consists of using index matched fluids with different densities. Here a pair of water solutions - isopropanol and NaCl - are identified that satisfy these requirements. In fact, they provide a density difference up to 5%, which is the largest reported for such fluid pairs. Additionally, by design, the kinematic viscosities of the solutions are identical. This greatly simplifies the analysis and subsequent simulations of the data. The spectral and temperature dependence of the solutions are fully characterized. In the near-field, shear layer roll-up is analyzed and characterized as a function of initial velocity profile. In the far-field, turbulence statistics are reported for two different scales, one capturing the entire jet at near Taylor microscale resolution, and the other, thanks to the careful refractive index matching of the liquids, resolving the Taylor scale at near Kolmogorov scale resolution. This is accomplished using a combination of TR-PIV and long-distance micro-PIV. The turbulence statistics obtained at various downstream locations and magnifications are obtained for density differences of 0%, 1%, and 3%. To validate the experimental methodology and provide a reference case for validation, the effect of initial velocity profile on the neutrally buoyant jet in the self-preserving regime is studied at two Reynolds numbers of 10,000 and 20,000. For the neutrally buoyant jet, it is found that independent of initial conditions the jet follows a self-similar behavior in the far-field; however, the spreading rate is strongly dependent on initial velocity profile. High magnification analysis at the small turbulent length scales shows a flow field where the mean statistics compare well to the larger field of view case. Investigation of the near-field shows the jet is strongly influenced by buoyancy, where an increase in vortex ring formation frequency and number of pairings occur. The buoyant jet with a 1% density difference shows an alteration of the centerline velocity decay, but the radial distribution of the mean axial velocity collapses well at all measurement locations. Jet formation dramatically changes for a buoyant jet with a 3% density difference, where the jet reaches a terminal height and spreads out horizontally at its neutral buoyancy location. Analysis of both the mean axial velocity and strain rates show the jet is no longer self-similar; for example, the mean centerline velocity does not decay uniformly as the jet develops. The centerline strain rates at this density difference also show trends which are strongly influenced by the altered centerline velocity. The overall centerline analysis shows that turbulence suppression occurs as a result of the stratification for both the 1% and 3% density difference. Analysis on the kinetic energy budget shows that the mean convection, production, transportation, and dissipation of energy is altered from stratification. High resolution data of the jet enable flow structures to be captured in the neutrally buoyant region of the flow. Vortices of different sizes are identified. Longer data sets are necessary to perform a statistical analysis of their distribution and to compare them to homogeneous environment case. This multi-scale analysis shows potential for studying energy transfer between length scales.

Instability Analysis of a Low-Density Gas Jet Injected into a High-Density Gas

NASA Technical Reports Server (NTRS)

Lawson, Anthony Layiwola

2001-01-01

The objective of this study was to determine the effects of buoyancy on the absolute instability of low-density gas jets injected into high-density gas mediums. Most of the existing analyses of low-density gas jets injected into a high-density ambient have been carried out neglecting effects of gravity. In order to investigate the influence of gravity on the near-injector development of the flow, a linear temporal stability analysis and a spatio-temporal stability analysis of a low-density round jet injected into a high-density ambient gas were performed. The flow was assumed to be isothermal and locally parallel; viscous and diffusive effects were ignored. The variables were represented as the sum of the mean value and a normal-mode small disturbance. An ordinary differential equation governing the amplitude of the pressure disturbance was derived. The velocity and density profiles in the shear layer, and the Froude number (signifying the effects of gravity) were the three important parameters in this equation. Together with the boundary conditions, an eigenvalue problem was formulated. Assuming that the velocity and density profiles in the shear layer to be represented by hyperbolic tangent functions, the eigenvalue problem was solved for various values of Froude number. The temporal growth rates and the phase velocity of the disturbances were obtained. It was found that the presence of variable density within the shear layer resulted in an increase in the temporal amplification rate of the disturbances and an increase in the range of unstable frequencies, accompanied by a reduction in the phase velocities of the disturbances. Also, the temporal growth rates of the disturbances were increased as the Froude number was reduced (i.e. gravitational effects increased), indicating the destabilizing role played by gravity. The spatio-temporal stability analysis was performed to determine the nature of the absolute instability of the jet. The roles of the density ratio, Froude number, Schmidt number, and the lateral shift between the density and velocity profiles on the jet s absolute instability were determined. Comparisons of the results with previous experimental studies show good agreement when the effects of these variables are combined together. Thus, the combination of these variables determines how absolutely unstable the jet will be. Experiments were carried out to observe the qualitative differences between a round low-density gas jet injected into a high-density gas (helium jet injected into air) and a round constant density jet (air jet injected into air). Flow visualizations and velocity measurements in the near-injector region of the helium jet show more mixing and spreading of the helium jet than the air jet. The vortex structures develop and contribute to the jet spreading causing the helium jet to oscillate.

Theoretical prediction of the impact of Auger recombination on charge collection from an ion track

NASA Technical Reports Server (NTRS)

Edmonds, Larry D.

1991-01-01

A recombination mechanism that significantly reduces charge collection from very dense ion tracks in silicon devices was postulated by Zoutendyk et al. The theoretical analysis presented here concludes that Auger recombination is such a mechanism and is of marginal importance for higher density tracks produced by 270-MeV krypton, but of major importance for higher density tracks. The analysis shows that recombination loss is profoundly affected by track diffusion. As the track diffuses, the density and recombination rate decrease so fast that the linear density (number of electron-hole pairs per unit length) approaches a non-zero limiting value as t yields infinity. Furthermore, the linear density is very nearly equal to this limiting value in a few picoseconds or less. When Auger recombination accompanies charge transport processes that have much longer time scales, it can be simulated by assigning a reduced linear energy transfer to the ion.

Energy transmission transformer for a wireless capsule endoscope: analysis of specific absorption rate and current density in biological tissue.

PubMed

Shiba, Kenji; Nagato, Tomohiro; Tsuji, Toshio; Koshiji, Kohji

2008-07-01

This paper reports on the electromagnetic influences on the analysis of biological tissue surrounding a prototype energy transmission system for a wireless capsule endoscope. Specific absorption rate (SAR) and current density were analyzed by electromagnetic simulator in a model consisting of primary coil and a human trunk including the skin, fat, muscle, small intestine, backbone, and blood. First, electric and magnetic strength in the same conditions as the analytical model were measured and compared to the analytical values to confirm the validity of the analysis. Then, SAR and current density as a function of frequency and output power were analyzed. The validity of the analysis was confirmed by comparing the analytical values with the measured ones. The SAR was below the basic restrictions of the International Commission on Nonionizing Radiation Protection (ICNIRP). At the same time, the results for current density show that the influence on biological tissue was lowest in the 300-400 kHz range, indicating that it was possible to transmit energy safely up to 160 mW. In addition, we confirmed that the current density has decreased by reducing the primary coil's current.

Fluctuations and symmetry energy in nuclear fragmentation dynamics.

PubMed

Colonna, M

2013-01-25

Within a dynamical description of nuclear fragmentation, based on the liquid-gas phase transition scenario, we explore the relation between neutron-proton density fluctuations and nuclear symmetry energy. We show that, along the fragmentation path, isovector fluctuations follow the evolution of the local density and approach an equilibrium value connected to the local symmetry energy. Higher-density regions are characterized by smaller average asymmetry and narrower isotopic distributions. This dynamical analysis points out that fragment final state isospin fluctuations can probe the symmetry energy of the density domains from which fragments originate.

Application of texture analysis method for mammogram density classification

NASA Astrophysics Data System (ADS)

Nithya, R.; Santhi, B.

2017-07-01

Mammographic density is considered a major risk factor for developing breast cancer. This paper proposes an automated approach to classify breast tissue types in digital mammogram. The main objective of the proposed Computer-Aided Diagnosis (CAD) system is to investigate various feature extraction methods and classifiers to improve the diagnostic accuracy in mammogram density classification. Texture analysis methods are used to extract the features from the mammogram. Texture features are extracted by using histogram, Gray Level Co-Occurrence Matrix (GLCM), Gray Level Run Length Matrix (GLRLM), Gray Level Difference Matrix (GLDM), Local Binary Pattern (LBP), Entropy, Discrete Wavelet Transform (DWT), Wavelet Packet Transform (WPT), Gabor transform and trace transform. These extracted features are selected using Analysis of Variance (ANOVA). The features selected by ANOVA are fed into the classifiers to characterize the mammogram into two-class (fatty/dense) and three-class (fatty/glandular/dense) breast density classification. This work has been carried out by using the mini-Mammographic Image Analysis Society (MIAS) database. Five classifiers are employed namely, Artificial Neural Network (ANN), Linear Discriminant Analysis (LDA), Naive Bayes (NB), K-Nearest Neighbor (KNN), and Support Vector Machine (SVM). Experimental results show that ANN provides better performance than LDA, NB, KNN and SVM classifiers. The proposed methodology has achieved 97.5% accuracy for three-class and 99.37% for two-class density classification.

Morphometric analysis of primary graft non-function in liver transplantation.

PubMed

Vertemati, M; Sabatella, G; Minola, E; Gambacorta, M; Goffredi, M; Vizzotto, L

2005-04-01

Primary graft non-function (PNF) is a life-threatening condition that is thought to be the consequence of microcirculation injury. The aim of the present study was to assess, with a computerized morphometric model, the morphological changes at reperfusion in liver biopsy specimens from patients who developed PNF after liver transplantation. Biopsy specimens were obtained at maximum ischaemia and at the end of reperfusion. Morphology included many stereological parameters, such as volumes of all parenchymal components, surface density, size distribution and mean diameter of hepatocytes. Other variables examined were intensive care unit stay, degree of steatosis, serum liver function tests and ischaemic time. In the postoperative period, the PNF group showed elevated serum levels of alanine transferase, decreased daily rate of bile production and prothrombin activity. Blood lactates were significantly higher in the PNF group than in a control group. When comparing groups, the volumetric parameters related to hepatocytes and sinusoids and the surface densities of the hepatic cells showed an inverse relationship. At the end of reperfusion, in PNF group the volume fraction of hepatocyte cytoplasm was decreased; in contrast, the volume fraction of sinusoidal lumen was markedly increased. The cell profiles showed the same inverse trend: the surface density of the parenchymal border of hepatocytes was decreased in PNF when compared with the control group, while the surface density of the vascular border was increased. In the PNF group, the surface density of the sinusoidal bed was directly correlated with alanine transferase, daily rate of bile production, prothrombin activity and cold ischaemic time. The alterations in hepatic architecture, as demonstrated by morphometric analysis in liver transplant recipients that developed PNF, provide additional information that may represent useful viability markers of the graft to complement conventional histological analysis.

Symbol recognition with kernel density matching.

PubMed

Zhang, Wan; Wenyin, Liu; Zhang, Kun

2006-12-01

We propose a novel approach to similarity assessment for graphic symbols. Symbols are represented as 2D kernel densities and their similarity is measured by the Kullback-Leibler divergence. Symbol orientation is found by gradient-based angle searching or independent component analysis. Experimental results show the outstanding performance of this approach in various situations.

Analysis of lipoprotein profiles of healthy cats by gel-permeation high-performance liquid chromatography

PubMed Central

MIZUTANI, Hisashi; SAKO, Toshinori; OKUDA, Hiroko; ARAI, Nobuaki; KURIYAMA, Koji; MORI, Akihiro; YOSHIMURA, Itaru; KOYAMA, Hidekazu

2016-01-01

Density gradient ultracentrifugation (DGUC) and gel electrophoresis are conventionally used to obtain lipoprotein profiles of animals. We recently applied high-performance liquid chromatography with a gel permeation column (GP-HPLC) and an on-line dual enzymatic system to dogs for lipoprotein profile analysis. We compared the GP-HPLC with DGUC as a method to obtain a feline lipoprotein profile. The lipoprotein profiles showed large and small peaks, which corresponded to high-density lipoprotein (HDL) and low-density lipoprotein (LDL), respectively, whereas very low-density lipoprotein (VLDL) and chylomicron (CM) were only marginally detected. This profile was very similar to that of dogs reported previously. Healthy cats also had a small amount of cholesterol-rich particles distinct from the normal LDL or HDL profile. There was no difference in lipoprotein profiles between the sexes, but males had a significantly larger LDL particle size (P=0.015). This study shows the feasibility of GP-HPLC for obtaining accurate lipoprotein profiles with small sample volumes and provides valuable reference data for healthy cats that should facilitate diagnoses. PMID:27170431

Evidence of m = 1 density mode (plasma cam) in Saturn's rotating magnetosphere

NASA Astrophysics Data System (ADS)

Goldstein, J.; Waite, J. H.; Burch, J. L.; Livi, R.

2016-03-01

Cassini field and plasma data measured in the rotating Saturn Longitude System 3 (SLS3) coordinate system show positive evidence of structure whose dominant azimuthal wave number is m = 1: a long-lived, nonaxisymmetric, cam-shaped, global plasma distribution in Saturn's magnetosphere. Previous studies have identified evidence of this plasma cam in wave-derived electron density data and in Cassini Plasma Spectrometer (CAPS) W+ ion counts data. In this paper we report the first comprehensive analysis of CAPS ion moments data to identify the m = 1 density cam. We employ a multiyear, multispecies database of 685,678 CAPS density values, binned into a 1 RS by 4.8° discretized grid, spanning 4-19 RS. Fourier (harmonic) analysis shows that at most radial distances the dominant azimuthal mode is m = 1, for both W+ and H+ ion distributions. The majority (63%) of m = 1 ion peaks are clustered in an SLS3 quadrant centered at 330°. The plasma cam's existence has important implications for the global interchange-driven convection cycle and is a clue to solving the mystery of the rotational periodicities in Saturn's magnetosphere.

Asymmetric simple exclusion process with position-dependent hopping rates: Phase diagram from boundary-layer analysis.

PubMed

Mukherji, Sutapa

2018-03-01

In this paper, we study a one-dimensional totally asymmetric simple exclusion process with position-dependent hopping rates. Under open boundary conditions, this system exhibits boundary-induced phase transitions in the steady state. Similarly to totally asymmetric simple exclusion processes with uniform hopping, the phase diagram consists of low-density, high-density, and maximal-current phases. In various phases, the shape of the average particle density profile across the lattice including its boundary-layer parts changes significantly. Using the tools of boundary-layer analysis, we obtain explicit solutions for the density profile in different phases. A detailed analysis of these solutions under different boundary conditions helps us obtain the equations for various phase boundaries. Next, we show how the shape of the entire density profile including the location of the boundary layers can be predicted from the fixed points of the differential equation describing the boundary layers. We discuss this in detail through several examples of density profiles in various phases. The maximal-current phase appears to be an especially interesting phase where the boundary layer flows to a bifurcation point on the fixed-point diagram.

Asymmetric simple exclusion process with position-dependent hopping rates: Phase diagram from boundary-layer analysis

NASA Astrophysics Data System (ADS)

Mukherji, Sutapa

2018-03-01

In this paper, we study a one-dimensional totally asymmetric simple exclusion process with position-dependent hopping rates. Under open boundary conditions, this system exhibits boundary-induced phase transitions in the steady state. Similarly to totally asymmetric simple exclusion processes with uniform hopping, the phase diagram consists of low-density, high-density, and maximal-current phases. In various phases, the shape of the average particle density profile across the lattice including its boundary-layer parts changes significantly. Using the tools of boundary-layer analysis, we obtain explicit solutions for the density profile in different phases. A detailed analysis of these solutions under different boundary conditions helps us obtain the equations for various phase boundaries. Next, we show how the shape of the entire density profile including the location of the boundary layers can be predicted from the fixed points of the differential equation describing the boundary layers. We discuss this in detail through several examples of density profiles in various phases. The maximal-current phase appears to be an especially interesting phase where the boundary layer flows to a bifurcation point on the fixed-point diagram.

Center-to-Limb Variability of Hot Coronal EUV Emissions During Solar Flares

NASA Astrophysics Data System (ADS)

Thiemann, E. M. B.; Chamberlin, P. C.; Eparvier, F. G.; Epp, L.

2018-02-01

It is generally accepted that densities of quiet-Sun and active region plasma are sufficiently low to justify the optically thin approximation, and this is commonly used in the analysis of line emissions from plasma in the solar corona. However, the densities of solar flare loops are substantially higher, compromising the optically thin approximation. This study begins with a radiative transfer model that uses typical solar flare densities and geometries to show that hot coronal emission lines are not generally optically thin. Furthermore, the model demonstrates that the observed line intensity should exhibit center-to-limb variability (CTLV), with flares observed near the limb being dimmer than those occurring near disk center. The model predictions are validated with an analysis of over 200 flares observed by the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO), which uses six lines, with peak formation temperatures between 8.9 and 15.8 MK, to show that limb flares are systematically dimmer than disk-center flares. The data are then used to show that the electron column density along the line of sight typically increases by 1.76 × 10^{19} cm^{-2} for limb flares over the disk-center flare value. It is shown that the CTLV of hot coronal emissions reduces the amount of ionizing radiation propagating into the solar system, and it changes the relative intensities of lines and bands commonly used for spectral analysis.

Chirality and orbital order in charge density waves

NASA Astrophysics Data System (ADS)

van Wezel, Jasper

2011-12-01

Helical arrangements of spins are common among magnetic materials. The first material to harbor a corkscrew pattern of charge density, on the other hand, was discovered only very recently. The nature of the order parameter is of key relevance, since rotating a magnetic vector around any propagation vector trivially yields a helical pattern. In contrast, the purely scalar charge density cannot straightforwardly support a chiral state. Here we use a Landau order parameter analysis to resolve this paradox, and show that the chiral charge order may be understood as a form of orbital ordering. We discuss the microscopic mechanism driving the transition and show it to be of a general form, thus allowing for a broad class of materials to display this novel type of orbital-ordered chiral charge density wave.

Cement Leakage in Percutaneous Vertebral Augmentation for Osteoporotic Vertebral Compression Fractures: Analysis of Risk Factors.

PubMed

Xie, Weixing; Jin, Daxiang; Ma, Hui; Ding, Jinyong; Xu, Jixi; Zhang, Shuncong; Liang, De

2016-05-01

The risk factors for cement leakage were retrospectively reviewed in 192 patients who underwent percutaneous vertebral augmentation (PVA). To discuss the factors related to the cement leakage in PVA procedure for the treatment of osteoporotic vertebral compression fractures. PVA is widely applied for the treatment of osteoporotic vertebral fractures. Cement leakage is a major complication of this procedure. The risk factors for cement leakage were controversial. A retrospective review of 192 patients who underwent PVA was conducted. The following data were recorded: age, sex, bone density, number of fractured vertebrae before surgery, number of treated vertebrae, severity of the treated vertebrae, operative approach, volume of injected bone cement, preoperative vertebral compression ratio, preoperative local kyphosis angle, intraosseous clefts, preoperative vertebral cortical bone defect, and ratio and type of cement leakage. To study the correlation between each factor and cement leakage ratio, bivariate regression analysis was employed to perform univariate analysis, whereas multivariate linear regression analysis was employed to perform multivariate analysis. The study included 192 patients (282 treated vertebrae), and cement leakage occurred in 100 vertebrae (35.46%). The vertebrae with preoperative cortical bone defects generally exhibited higher cement leakage ratio, and the leakage is typically type C. Vertebrae with intact cortical bones before the procedure tend to experience type S leakage. Univariate analysis showed that patient age, bone density, number of fractured vertebrae before surgery, and vertebral cortical bone were associated with cement leakage ratio (P<0.05). Multivariate analysis showed that the main factors influencing bone cement leakage are bone density and vertebral cortical bone defect, with standardized partial regression coefficients of -0.085 and 0.144, respectively. High bone density and vertebral cortical bone defect are independent risk factors associated with bone cement leakage.

Impact of stone density on outcomes in percutaneous nephrolithotomy (PCNL): an analysis of the clinical research office of the endourological society (CROES) pcnl global study database.

PubMed

Anastasiadis, Anastasios; Onal, Bulent; Modi, Pranjal; Turna, Burak; Duvdevani, Mordechai; Timoney, Anthony; Wolf, J Stuart; De La Rosette, Jean

2013-12-01

This study aimed to explore the relationship between stone density and outcomes of percutaneous nephrolithotomy (PCNL) using the Clinical Research Office of the Endourological Society (CROES) PCNL Global Study database. Patients undergoing PCNL treatment were assigned to a low stone density [LSD, ≤ 1000 Hounsfield units (HU)] or high stone density (HSD, > 1000 HU) group based on the radiological density of the primary renal stone. Preoperative characteristics and outcomes were compared in the two groups. Retreatment for residual stones was more frequent in the LSD group. The overall stone-free rate achieved was higher in the HSD group (79.3% vs 74.8%, p = 0.113). By univariate regression analysis, the probability of achieving a stone-free outcome peaked at approximately 1250 HU. Below or above this density resulted in lower treatment success, particularly at very low HU values. With increasing radiological stone density, operating time decreased to a minimum at approximately 1000 HU, then increased with further increase in stone density. Multivariate non-linear regression analysis showed a similar relationship between the probability of a stone-free outcome and stone density. Higher treatment success rates were found with low stone burden, pelvic stone location and use of pneumatic lithotripsy. Very low and high stone densities are associated with lower rates of treatment success and longer operating time in PCNL. Preoperative assessment of stone density may help in the selection of treatment modality for patients with renal stones.

Quantitative analysis of drainage obtained from aerial photographs and RBV/LANDSAT images

NASA Technical Reports Server (NTRS)

Dejesusparada, N. (Principal Investigator); Formaggio, A. R.; Epiphanio, J. C. N.; Filho, M. V.

1981-01-01

Data obtained from aerial photographs (1:60,000) and LANDSAT return beam vidicon imagery (1:100,000) concerning drainage density, drainage texture, hydrography density, and the average length of channels were compared. Statistical analysis shows that significant differences exist in data from the two sources. The highly drained area lost more information than the less drained area. In addition, it was observed that the loss of information about the number of rivers was higher than that about the length of the channels.

Density enhancement mechanism of upwind schemes for low Mach number flows

NASA Astrophysics Data System (ADS)

Lin, Bo-Xi; Yan, Chao; Chen, Shu-Sheng

2018-06-01

Many all-speed Roe schemes have been proposed to improve performance in terms of low speeds. Among them, the F-Roe and T-D-Roe schemes have been found to get incorrect density fluctuation in low Mach flows, which is expected to be with the square of Mach number. Asymptotic analysis presents the mechanism of how the density fluctuation problem relates to the incorrect order of terms in the energy equation \\tilde{ρ {\\tilde{a}} {\\tilde{U}}Δ U}. It is known that changing the upwind scheme coefficients of the pressure-difference dissipation term D^P and the velocity-difference dissipation term in the momentum equation D^{ρ U} to the order of O(c^{-1}) and O(c0) can improve the level of pressure and velocity accuracy at low speeds. This paper shows that corresponding changes in energy equation can also improve the density accuracy in low speeds. We apply this modification to a recently proposed scheme, TV-MAS, to get a new scheme, TV-MAS2. Unsteady Gresho vortex flow, double shear-layer flow, low Mach number flows over the inviscid cylinder, and NACA0012 airfoil show that energy equation modification in these schemes can obtain the expected square Ma scaling of density fluctuations, which is in good agreement with corresponding asymptotic analysis. Therefore, this density correction is expected to be widely implemented into all-speed compressible flow solvers.

Hyperspectral Biofilm Classification Analysis for Carrying Capacity of Migratory Birds in the South Bay Salt Ponds

NASA Technical Reports Server (NTRS)

Hsu, Wei-Chen; Kuss, Amber Jean; Ketron, Tyler; Nguyen, Andrew; Remar, Alex Covello; Newcomer, Michelle; Fleming, Erich; Debout, Leslie; Debout, Brad; Detweiler, Angela;

Independent Component Analysis of Textures

NASA Technical Reports Server (NTRS)

Manduchi, Roberto; Portilla, Javier

2000-01-01

A common method for texture representation is to use the marginal probability densities over the outputs of a set of multi-orientation, multi-scale filters as a description of the texture. We propose a technique, based on Independent Components Analysis, for choosing the set of filters that yield the most informative marginals, meaning that the product over the marginals most closely approximates the joint probability density function of the filter outputs. The algorithm is implemented using a steerable filter space. Experiments involving both texture classification and synthesis show that compared to Principal Components Analysis, ICA provides superior performance for modeling of natural and synthetic textures.

Thiophenic compounds adsorption on Na(I)Y and rare earth exchanged Y zeolites: a density functional theory study.

PubMed

Gao, Xionghou; Geng, Wei; Zhang, Haitao; Zhao, Xuefei; Yao, Xiaojun

2013-11-01

We have theoretically investigated the adsorption of thiophene, benzothiophene, dibenzothiophene on Na(I)Y and rare earth exchanged La(III)Y, Ce(III)Y, Pr(III)Y Nd(III)Y zeolites by density functional theory calculations. The calculated results show that except benzothiophene adsorbed on Na(I)Y with a stand configuration, the stable adsorption structures of other thiophenic compounds on zeolites exhibit lying configurations. Adsorption energies of thiophenic compounds on the Na(I)Y are very low, and decrease with the increase of the number of benzene rings in thiophenic compounds. All rare earth exchanged zeolites exhibit strong interaction with thiophene. La(III)Y and Nd(III)Y zeolites are found to show enhanced adsorption energies to benzothiophene and Pr(III)Y zeolites are favorable for dibenzothiophene adsorption. The analysis of the electronic total charge density and electron orbital overlaps show that the thiophenic compounds interact with zeolites by π-electrons of thiophene ring and exchanged metal atom. Mulliken charge populations analysis reveals that adsorption energies are strongly dependent on the charge transfer of thiophenic molecule and exchanged metal atom.

Computer image analysis of etched tracks from ionizing radiation

NASA Technical Reports Server (NTRS)

Blanford, George E.

1994-01-01

I proposed to continue a cooperative research project with Dr. David S. McKay concerning image analysis of tracks. Last summer we showed that we could measure track densities using the Oxford Instruments eXL computer and software that is attached to an ISI scanning electron microscope (SEM) located in building 31 at JSC. To reduce the dependence on JSC equipment, we proposed to transfer the SEM images to UHCL for analysis. Last summer we developed techniques to use digitized scanning electron micrographs and computer image analysis programs to measure track densities in lunar soil grains. Tracks were formed by highly ionizing solar energetic particles and cosmic rays during near surface exposure on the Moon. The track densities are related to the exposure conditions (depth and time). Distributions of the number of grains as a function of their track densities can reveal the modality of soil maturation. As part of a consortium effort to better understand the maturation of lunar soil and its relation to its infrared reflectance properties, we worked on lunar samples 67701,205 and 61221,134. These samples were etched for a shorter time (6 hours) than last summer's sample and this difference has presented problems for establishing the correct analysis conditions. We used computer counting and measurement of area to obtain preliminary track densities and a track density distribution that we could interpret for sample 67701,205. This sample is a submature soil consisting of approximately 85 percent mature soil mixed with approximately 15 percent immature, but not pristine, soil.

Characterizing bonding patterns in diradicals and triradicals by density-based wave function analysis: A uniform approach

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

Orms, Natalie; Rehn, Dirk; Dreuw, Andreas

Density-based wave function analysis enables unambiguous comparisons of electronic structure computed by different methods and removes ambiguity of orbital choices. Here, we use this tool to investigate the performance of different spin-flip methods for several prototypical diradicals and triradicals. In contrast to previous calibration studies that focused on energy gaps between high and low spin-states, we focus on the properties of the underlying wave functions, such as the number of effectively unpaired electrons. Comparison of different density functional and wave function theory results provides insight into the performance of the different methods when applied to strongly correlated systems such asmore » polyradicals. We also show that canonical molecular orbitals for species like large copper-containing diradicals fail to correctly represent the underlying electronic structure due to highly non-Koopmans character, while density-based analysis of the same wave function delivers a clear picture of bonding pattern.« less

Characterizing bonding patterns in diradicals and triradicals by density-based wave function analysis: A uniform approach

DOE PAGES

Orms, Natalie; Rehn, Dirk; Dreuw, Andreas; ...

2017-12-21

Density-based wave function analysis enables unambiguous comparisons of electronic structure computed by different methods and removes ambiguity of orbital choices. Here, we use this tool to investigate the performance of different spin-flip methods for several prototypical diradicals and triradicals. In contrast to previous calibration studies that focused on energy gaps between high and low spin-states, we focus on the properties of the underlying wave functions, such as the number of effectively unpaired electrons. Comparison of different density functional and wave function theory results provides insight into the performance of the different methods when applied to strongly correlated systems such asmore » polyradicals. We also show that canonical molecular orbitals for species like large copper-containing diradicals fail to correctly represent the underlying electronic structure due to highly non-Koopmans character, while density-based analysis of the same wave function delivers a clear picture of bonding pattern.« less

May–June Maximum Temperature Reconstruction from Mean Earlywood Density in North Central China and Its Linkages to the Summer Monsoon Activities

PubMed Central

Chen, Feng; Yuan, Yujiang

2014-01-01

Cores of Pinus tabulaformis from Tianshui were subjected to densitometric analysis to obtain mean earlywood density data. Climate response analysis indicates that May–June maximum temperature is the main factor limiting the mean earlywood density (EWD) of Chinese pine trees in the Shimen Mountains. Based on the EWD chronology, we have reconstructed May–June maximum temperature 1666 to 2008 for Tianshui, north central China. The reconstruction explains 40.1% of the actual temperature variance during the common period 1953–2008. The temperature reconstruction is representative of temperature conditions over a large area to the southeast and northwest of the sampling site. Preliminary analysis of links between large-scale climatic variation and the temperature reconstruction shows that there is a relationship between extremes in spring temperature and anomalous atmospheric circulation in the region. It is thus revealed that the mean earlywood density chronology of Pinus tabulaformis has enough potential to reconstruct the temperature variability further into the past. PMID:25207554

Linear Stability Analysis of Gravitational Effects on a Low-Density Gas Jet Injected into a High-Density Medium

NASA Technical Reports Server (NTRS)

Lawson, Anthony L.; Parthasarathy, Ramkumar N.

2005-01-01

The objective of this study was to determine the effects of buoyancy on the absolute instability of low-density gas jets injected into high-density gas mediums. Most of the existing analyses of low-density gas jets injected into a high-density ambient have been carried out neglecting effects of gravity. In order to investigate the influence of gravity on the near-injector development of the flow, a spatio-temporal stability analysis of a low-density round jet injected into a high-density ambient gas was performed. The flow was assumed to be isothermal and locally parallel; viscous and diffusive effects were ignored. The variables were represented as the sum of the mean value and a normal-mode small disturbance. An ordinary differential equation governing the amplitude of the pressure disturbance was derived. The velocity and density profiles in the shear layer, and the Froude number (signifying the effects of gravity) were the three important parameters in this equation. Together with the boundary conditions, an eigenvalue problem was formulated. Assuming that the velocity and density profiles in the shear layer to be represented by hyperbolic tangent functions, the eigenvalue problem was solved for various values of Froude number. The Briggs-Bers criterion was combined with the spatio-temporal stability analysis to determine the nature of the absolute instability of the jet whether absolutely or convectively unstable. The roles of the density ratio, Froude number, Schmidt number, and the lateral shift between the density and velocity profiles on the absolute instability of the jet were determined. Comparisons of the results with previous experimental studies show good agreement when the effects of these variables are combined together. Thus, the combination of these variables determines how absolutely unstable the jet will be.

High and low density development in Puerto Rico

Treesearch

William A. Gould; Sebastian Martinuzzi; Olga M. Ramos Gonzalez

2008-01-01

This map shows the distribution of high and low density developed lands in Puerto Rico (Martinuzzi et al. 2007). The map was created using a mosaic of Landsat ETM+ images that range from the years 2000 to 2003. The developed land cover was classified using the Iterative Self-Organizing Data Analysis Technique (ISODATA) unsupervised classification (ERDAS 2003)....

A wave function for stock market returns

NASA Astrophysics Data System (ADS)

Ataullah, Ali; Davidson, Ian; Tippett, Mark

2009-02-01

The instantaneous return on the Financial Times-Stock Exchange (FTSE) All Share Index is viewed as a frictionless particle moving in a one-dimensional square well but where there is a non-trivial probability of the particle tunneling into the well’s retaining walls. Our analysis demonstrates how the complementarity principle from quantum mechanics applies to stock market prices and of how the wave function presented by it leads to a probability density which exhibits strong compatibility with returns earned on the FTSE All Share Index. In particular, our analysis shows that the probability density for stock market returns is highly leptokurtic with slight (though not significant) negative skewness. Moreover, the moments of the probability density determined under the complementarity principle employed here are all convergent - in contrast to many of the probability density functions on which the received theory of finance is based.

Long-range analysis of density fitting in extended systems

NASA Astrophysics Data System (ADS)

Varga, Scarontefan

Density fitting scheme is analyzed for the Coulomb problem in extended systems from the correctness of long-range behavior point of view. We show that for the correct cancellation of divergent long-range Coulomb terms it is crucial for the density fitting scheme to reproduce the overlap matrix exactly. It is demonstrated that from all possible fitting metric choices the Coulomb metric is the only one which inherently preserves the overlap matrix for infinite systems with translational periodicity. Moreover, we show that by a small additional effort any non-Coulomb metric fit can be made overlap-preserving as well. The problem is analyzed for both ordinary and Poisson basis set choices.

Production of litter and detritus related to the density of mangrove

NASA Astrophysics Data System (ADS)

Budi Mulya, Miswar; Arlen, HJ

2018-03-01

Research about the production of leaf litter and detritus related to the density of mangrove trees has been done. The aims of this research are to know and analyze the amount of litter and detritus produced to the density of mangrove trees. The production and collection of leaf litter were carried out in five stations. Production of detritus and decomposition rate were calculated by measuring its dry weight. The density and level of mangrove trees were determined using transect quadratic method. The relationship between the leaf litter and detritus production ratio related to mangrove density were then analyzed. Results showed that mangrove trees with the density of 766.67 ind ha‑1 ccould produce the amount of litter and detritus to about 28597.33 gha‑1day‑1and 1099.35 gha‑1day‑1 while mangrove trees with the density of 1300 ind ha‑1 could produce the amount of litter and detritus to about 35093.33 g/ha/day and 1216.68 gha‑1day‑1 respectively. Data analysis showed that the increment of mangrove density is linearly related to the production increment of litter and detritus.

Central depression in nucleonic densities: Trend analysis in the nuclear density functional theory approach

NASA Astrophysics Data System (ADS)

Schuetrumpf, B.; Nazarewicz, W.; Reinhard, P.-G.

2017-08-01

Background: The central depression of nucleonic density, i.e., a reduction of density in the nuclear interior, has been attributed to many factors. For instance, bubble structures in superheavy nuclei are believed to be due to the electrostatic repulsion. In light nuclei, the mechanism behind the density reduction in the interior has been discussed in terms of shell effects associated with occupations of s orbits. Purpose: The main objective of this work is to reveal mechanisms behind the formation of central depression in nucleonic densities in light and heavy nuclei. To this end, we introduce several measures of the internal nucleonic density. Through the statistical analysis, we study the information content of these measures with respect to nuclear matter properties. Method: We apply nuclear density functional theory with Skyrme functionals. Using the statistical tools of linear least square regression, we inspect correlations between various measures of central depression and model parameters, including nuclear matter properties. We study bivariate correlations with selected quantities as well as multiple correlations with groups of parameters. Detailed correlation analysis is carried out for 34Si for which a bubble structure has been reported recently, 48Ca, and N =82 , 126, and 184 isotonic chains. Results: We show that the central depression in medium-mass nuclei is very sensitive to shell effects, whereas for superheavy systems it is firmly driven by the electrostatic repulsion. An appreciable semibubble structure in proton density is predicted for 294Og, which is currently the heaviest nucleus known experimentally. Conclusion: Our correlation analysis reveals that the central density indicators in nuclei below 208Pb carry little information on parameters of nuclear matter; they are predominantly driven by shell structure. On the other hand, in the superheavy nuclei there exists a clear relationship between the central nucleonic density and symmetry energy.

Kinetic simulations of the stability of a plasma confined by the magnetic field of a current rod

NASA Astrophysics Data System (ADS)

Tonge, J.; Leboeuf, J. N.; Huang, C.; Dawson, J. M.

2003-09-01

The kinetic stability of a plasma in the magnetic field of a current rod is investigated for various temperature and density profiles using three-dimensional particle-in-cell simulations. Such a plasma obeys similar physics to a plasma in a dipole magnetic field, while it is easier to perform computer simulations, and do theoretical analysis, of a plasma in the field of a current rod. Simple energy principle calculations and simulations with a variety of temperature and density profiles show that the plasma is stable to interchange for pressure profiles proportional to r-10/3. As predicted by theory the simulations also show that the density profile will be stationary as long as density is proportional to r-2 even though the temperature profile may not be stable.

Hierarchical Bayesian spatial models for alcohol availability, drug "hot spots" and violent crime.

PubMed

Zhu, Li; Gorman, Dennis M; Horel, Scott

2006-12-07

Ecologic studies have shown a relationship between alcohol outlet densities, illicit drug use and violence. The present study examined this relationship in the City of Houston, Texas, using a sample of 439 census tracts. Neighborhood sociostructural covariates, alcohol outlet density, drug crime density and violent crime data were collected for the year 2000, and analyzed using hierarchical Bayesian models. Model selection was accomplished by applying the Deviance Information Criterion. The counts of violent crime in each census tract were modelled as having a conditional Poisson distribution. Four neighbourhood explanatory variables were identified using principal component analysis. The best fitted model was selected as the one considering both unstructured and spatial dependence random effects. The results showed that drug-law violation explained a greater amount of variance in violent crime rates than alcohol outlet densities. The relative risk for drug-law violation was 2.49 and that for alcohol outlet density was 1.16. Of the neighbourhood sociostructural covariates, males of age 15 to 24 showed an effect on violence, with a 16% decrease in relative risk for each increase the size of its standard deviation. Both unstructured heterogeneity random effect and spatial dependence need to be included in the model. The analysis presented suggests that activity around illicit drug markets is more strongly associated with violent crime than is alcohol outlet density. Unique among the ecological studies in this field, the present study not only shows the direction and magnitude of impact of neighbourhood sociostructural covariates as well as alcohol and illicit drug activities in a neighbourhood, it also reveals the importance of applying hierarchical Bayesian models in this research field as both spatial dependence and heterogeneity random effects need to be considered simultaneously.

Does uneven geographic distribution of urologists effect bladder and prostate cancers mortality? National health insurance data in Korea from 2007-2011.

PubMed

Kim, Jae Heon; Sun, Hwa Yeon; Kim, Hyun Jung; Ko, Young Myoung; Chun, Dong-Il; Park, Jae Young

2017-09-12

The relationship between distribution of urologists and mortality of bladder and prostate cancers has not been clearly established. The aim of this study was to investigate the relationship between uneven distribution of urologists and urologic cancer specific mortality at country level. Data from the National Health Insurance Service and National Statistical Office in Korea from 2007 to 2011 were analyzed in this ecological study. Univariate and multivariable regression analyses were performed to determine risk factors for age standardized mortality rates (ASMR) of bladder and prostate cancers. Linear regression analysis showed a markedly ( p < 0.001) uneven distribution of urologists between metropolitan and non-metropolitan areas. There was no significant difference in cancer specific ASMRs for either bladder cancer or prostate cancer. Univariate analysis after adjusting for time showed that country area, urologist density, and income were significant factors affecting bladder cancer incidence ( p < 0.001, p = 0.013, and p < 0.001, respectively). It also showed that the number of training hospitals was a significant factor for prostate cancer incidence ( p = 0.002). Although country area showed borderline significance ( p = 0.056) for ASMR of bladder cancer, urologist density was not related to ASMR of bladder cancer or prostate cancer. Although there was a marked difference in urologist density between metropolitan and non-metropolitan areas for these years analyzed, mortality rates of bladder and prostate cancers were not significantly affected by country area or urologist density.

Does uneven geographic distribution of urologists effect bladder and prostate cancers mortality? National health insurance data in Korea from 2007–2011

PubMed Central

Kim, Jae Heon; Sun, Hwa Yeon; Kim, Hyun Jung; Ko, Young Myoung; Chun, Dong-Il; Park, Jae Young

2017-01-01

The relationship between distribution of urologists and mortality of bladder and prostate cancers has not been clearly established. The aim of this study was to investigate the relationship between uneven distribution of urologists and urologic cancer specific mortality at country level. Data from the National Health Insurance Service and National Statistical Office in Korea from 2007 to 2011 were analyzed in this ecological study. Univariate and multivariable regression analyses were performed to determine risk factors for age standardized mortality rates (ASMR) of bladder and prostate cancers. Linear regression analysis showed a markedly (p < 0.001) uneven distribution of urologists between metropolitan and non-metropolitan areas. There was no significant difference in cancer specific ASMRs for either bladder cancer or prostate cancer. Univariate analysis after adjusting for time showed that country area, urologist density, and income were significant factors affecting bladder cancer incidence (p < 0.001, p = 0.013, and p < 0.001, respectively). It also showed that the number of training hospitals was a significant factor for prostate cancer incidence (p = 0.002). Although country area showed borderline significance (p = 0.056) for ASMR of bladder cancer, urologist density was not related to ASMR of bladder cancer or prostate cancer. Although there was a marked difference in urologist density between metropolitan and non-metropolitan areas for these years analyzed, mortality rates of bladder and prostate cancers were not significantly affected by country area or urologist density. PMID:29029431

Analysis of current density and specific absorption rate in biological tissue surrounding an air-core type of transcutaneous transformer for an artificial heart.

PubMed

Shiba, Kenji; Nukaya, Masayuki; Tsuji, Toshio; Koshiji, Kohji

2006-01-01

This paper reports on the specific absorption rate (SAR) and the current density analysis of biological tissue surrounding an air-core type of transcutaneous transformer for an artificial heart. The electromagnetic field in the biological tissue surrounding the transformer was analyzed by the transmission-line modeling method, and the SAR and current density as a function of frequency (200k-1 MHz) for a transcutaneous transmission of 20 W were calculated. The model's biological tissue has three layers including the skin, fat and muscle. As a result, the SAR in the vicinity of the transformer is sufficiently small and the normalized SAR value, which is divided by the ICNIRP's basic restriction, is 7 x 10(-3) or less. On the contrary, the current density is slightly in excess of the ICNIRP's basic restrictions as the frequency falls and the output voltage rises. Normalized current density is from 0.2 to 1.2. In addition, the layer in which the current's density is maximized depends on the frequency, the muscle in the low frequency (<700 kHz) and the skin in the high frequency (>700 kHz). The result shows that precision analysis taking into account the biological properties is very important for developing the transcutaneous transformer for TAH.

Statistical analysis of electroconvection near an ion-selective membrane in the highly chaotic regime

NASA Astrophysics Data System (ADS)

Druzgalski, Clara; Mani, Ali

2016-11-01

We investigate electroconvection and its impact on ion transport in a model system comprised of an ion-selective membrane, an aqueous electrolyte, and an external electric field applied normal to the membrane. We develop a direct numerical simulation code to solve the governing Poisson-Nernst-Planck and Navier-Stokes equations in three dimensions using a specialized parallel numerical algorithm and sufficient resolution to capture the high frequency and high wavenumber physics. We show a comprehensive statistical analysis of the transport phenomena in the highly chaotic regime. Qualitative and quantitative comparisons of two-dimensional (2D) and 3D simulations include prediction of the mean concentration fields as well as the spectra of concentration, charge density, and velocity signals. Our analyses reveal a significant quantitative difference between 2D and 3D electroconvection. Furthermore, we show that high-intensity yet short-lived current density hot spots appear randomly on the membrane surface, contributing significantly to the mean current density. By examining cross correlations between current density on the membrane and other field quantities we explore the physical mechanisms leading to current hot spots. We also present analysis of transport fluxes in the context of ensemble-averaged equations. Our analysis reveals that in the highly chaotic regime the mixing layer (ML), which spans the majority of the domain extent, is governed by advective fluctuations. Furthermore, we show that in the ML the mean electromigration fluxes cancel out for positive and negative ions, indicating that the mean transport of total salt content within the ML can be represented via the electroneutral approximation. Finally, we present an assessment of the importance of different length scales in enhancing transport by computing the cross covariance of concentration and velocity fluctuations in the wavenumber space. Our analysis indicates that in the majority of the domain the large scales contribute most significantly to transport, while the effects of small scales become more appreciable in regions very near the membrane.

Comparing ab initio density-functional and wave function theories: the impact of correlation on the electronic density and the role of the correlation potential.

PubMed

Grabowski, Ireneusz; Teale, Andrew M; Śmiga, Szymon; Bartlett, Rodney J

2011-09-21

The framework of ab initio density-functional theory (DFT) has been introduced as a way to provide a seamless connection between the Kohn-Sham (KS) formulation of DFT and wave-function based ab initio approaches [R. J. Bartlett, I. Grabowski, S. Hirata, and S. Ivanov, J. Chem. Phys. 122, 034104 (2005)]. Recently, an analysis of the impact of dynamical correlation effects on the density of the neon atom was presented [K. Jankowski, K. Nowakowski, I. Grabowski, and J. Wasilewski, J. Chem. Phys. 130, 164102 (2009)], contrasting the behaviour for a variety of standard density functionals with that of ab initio approaches based on second-order Møller-Plesset (MP2) and coupled cluster theories at the singles-doubles (CCSD) and singles-doubles perturbative triples [CCSD(T)] levels. In the present work, we consider ab initio density functionals based on second-order many-body perturbation theory and coupled cluster perturbation theory in a similar manner, for a range of small atomic and molecular systems. For comparison, we also consider results obtained from MP2, CCSD, and CCSD(T) calculations. In addition to this density based analysis, we determine the KS correlation potentials corresponding to these densities and compare them with those obtained for a range of ab initio density functionals via the optimized effective potential method. The correlation energies, densities, and potentials calculated using ab initio DFT display a similar systematic behaviour to those derived from electronic densities calculated using ab initio wave function theories. In contrast, typical explicit density functionals for the correlation energy, such as VWN5 and LYP, do not show behaviour consistent with this picture of dynamical correlation, although they may provide some degree of correction for already erroneous explicitly density-dependent exchange-only functionals. The results presented here using orbital dependent ab initio density functionals show that they provide a treatment of exchange and correlation contributions within the KS framework that is more consistent with traditional ab initio wave function based methods.

Comparison of dental implant stabilities by impact response and resonance frequencies using artificial bone.

PubMed

Kim, Dae-Seung; Lee, Woo-Jin; Choi, Soon-Chul; Lee, Sam-Sun; Heo, Min-Suk; Huh, Kyung-Hoe; Kim, Tae-Il; Yi, Won-Jin

2014-06-01

We compared implant stability as determined by the peak frequency from the impact response with the implant stability quotient (ISQ) by resonance frequency analysis (RFA) in various artificial bone conditions. The clinical bone conditions were simulated using an artificial bone material with different cortical thicknesses and trabecular densities. The artificial bone material was solid, rigid polyurethane. The polyurethane foam of 0.8g/cm(3) density was used for the cortical bone layer, and that of 0.08, 0.16, 0.24, 0.32, and 0.48g/cm(3) densities for the trabecular bone layer. The cortical bone material of 4 different thicknesses (1.4, 1.6, 1.8, and 2.0mm) was attached to the trabecular bone with varying density. Two types of dental implants (10 and 13mm lengths of 4.0mm diameter) were placed into the artificial bone blocks. An inductive sensor was used to measure the vibration caused by tapping the adapter-implant assembly. The peak frequency of the power spectrum of the impact response was used as the criterion for implant stability. The ISQ value was also measured for the same conditions. The stability, as measured by peak frequency (SPF) and ISQ value, increased as the trabecular density and the cortical density increased in linear regression analysis. The SPF and ISQ values were highly correlated with each other when the trabecular bone density and cortical bone thickness changed (Pearson correlation=0.90, p<0.01). The linear regression of the SPF with the cortical bone thickness showed higher goodness of fit (R(2) measure) than the ISQ value with the cortical bone thickness. The SPF could differentiate implantation conditions as many as the ISQ value when the trabecular bone density and the cortical density changed. However, the ISQ value was not consistent with the general stability tendency in some conditions. The SPF showed better consistency and differentiability with implant stability than the ISQ value by resonance frequency analysis in the various implantation conditions. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Stochastic seasonality and nonlinear density-dependent factors regulate population size in an African rodent

USGS Publications Warehouse

Leirs, H.; Stenseth, N.C.; Nichols, J.D.; Hines, J.E.; Verhagen, R.; Verheyen, W.

1997-01-01

Ecology has long been troubled by the controversy over how populations are regulated. Some ecologists focus on the role of environmental effects, whereas others argue that density-dependent feedback mechanisms are central. The relative importance of both processes is still hotly debated, but clear examples of both processes acting in the same population are rare. Keyfactor analysis (regression of population changes on possible causal factors) and time-series analysis are often used to investigate the presence of density dependence, but such approaches may be biased and provide no information on actual demographic rates. Here we report on both density-dependent and density-independent effects in a murid rodent pest species, the multimammate rat Mastomys natalensis (Smith, 1834), using statistical capture-recapture models. Both effects occur simultaneously, but we also demonstrate that they do not affect all demographic rates in the same way. We have incorporated the obtained estimates of demographic rates in a population dynamics model and show that the observed dynamics are affected by stabilizing nonlinear density-dependent components coupled with strong deterministic and stochastic seasonal components.

Ion diffusion may introduce spurious current sources in current-source density (CSD) analysis.

PubMed

Halnes, Geir; Mäki-Marttunen, Tuomo; Pettersen, Klas H; Andreassen, Ole A; Einevoll, Gaute T

2017-07-01

Current-source density (CSD) analysis is a well-established method for analyzing recorded local field potentials (LFPs), that is, the low-frequency part of extracellular potentials. Standard CSD theory is based on the assumption that all extracellular currents are purely ohmic, and thus neglects the possible impact from ionic diffusion on recorded potentials. However, it has previously been shown that in physiological conditions with large ion-concentration gradients, diffusive currents can evoke slow shifts in extracellular potentials. Using computer simulations, we here show that diffusion-evoked potential shifts can introduce errors in standard CSD analysis, and can lead to prediction of spurious current sources. Further, we here show that the diffusion-evoked prediction errors can be removed by using an improved CSD estimator which accounts for concentration-dependent effects. NEW & NOTEWORTHY Standard CSD analysis does not account for ionic diffusion. Using biophysically realistic computer simulations, we show that unaccounted-for diffusive currents can lead to the prediction of spurious current sources. This finding may be of strong interest for in vivo electrophysiologists doing extracellular recordings in general, and CSD analysis in particular. Copyright © 2017 the American Physiological Society.

Development of high energy density supercapacitor through hydrothermal synthesis of RGO/nano-structured cobalt sulphide composites

NASA Astrophysics Data System (ADS)

Jana, Milan; Saha, Sanjit; Samanta, Pranab; Murmu, Naresh Chandra; Kim, Nam Hoon; Kuila, Tapas; Lee, Joong Hee

2015-02-01

Co9S8/reduced graphene oxide (RGO) composites were prepared on nickel foam substrate through hydrothermal reaction and used directly as supercapacitor electrode. The field emission scanning electron microscopy analysis of the composites showed the formation of Co9S8 nano-rods on the RGO surfaces. The average crystal size of the Co9S8 nano rods grown on the RGO sheets were ˜25-36 nm as calculated from x-ray diffraction analysis. The reduction of graphene oxide (GO) was confirmed by Raman and x-ray photoelectron spectroscopy analysis. The electrical conductivity of the Co9S8/RGO composite was recorded as 1690 S m-1 at room temperature, which is much higher than that of pure GO further confirming the hydrothermal reduction of GO. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy were investigated to check the electrochemical performances of the Co9S8/RGO composites. The Co9S8/RGO composites supported on nickel foam showed very high specific capacitance (Sc)(1349 F g-1 at a current density of 2.2 A g-1), energy density (68.6 W h kg-1) and power density (1319 W kg-1) in 6 M KOH electrolyte. The retention in Sc of the composite electrode was found to be ˜96% after 1000 charge-discharge cycles.

Influence of Fe substitution on structure and Raman spectra of La0.67Sr0.33MnO3: Experimental and density functional studies

NASA Astrophysics Data System (ADS)

Astik, Nidhi M.; Soni, Himadri; Jha, Prafulla K.; Sathe, Vasant

2018-07-01

We present experimental and theoretical studies on the effect of Fe doping at Mn site, on the structural, morphological, electronic and vibrational properties of La0.67Sr0.3MnO3 nanoparticle. The samples of La0.67Sr0.3MnO3 and La0.67Sr0.33Mn1-xFexO3 (x = 0.15, 0.25 and 0.35) have been prepared by ball milling route. The phase purity of these samples has been confirmed using X-ray diffraction, while compositional analysis is done using EDAX. The morphological analysis done using scanning microscope indicates the agglomeration. The vibrational analysis which is done using Raman scattering and density functional theory (DFT) calculations show a substantial shift in A1g and Eg modes with Fe doping. The Eg modes become broader with Fe doping. The UV-visible spectra were measured in the energy range of 1-5 eV and compared with DFT results. The spin polarized density functional calculations show an increase in density of states at Fermi level due to MnO6octahedra modification and significant magnetism on Fe doping. The total magnetic moment is found from 16 to 17 μB for considered concentration. The effective mass of carriers is also calculated and found increasing with increasing concentration.

Spatial Differentiation of Landscape Values in the Murray River Region of Victoria, Australia

NASA Astrophysics Data System (ADS)

Zhu, Xuan; Pfueller, Sharron; Whitelaw, Paul; Winter, Caroline

2010-05-01

This research advances the understanding of the location of perceived landscape values through a statistically based approach to spatial analysis of value densities. Survey data were obtained from a sample of people living in and using the Murray River region, Australia, where declining environmental quality prompted a reevaluation of its conservation status. When densities of 12 perceived landscape values were mapped using geographic information systems (GIS), valued places clustered along the entire river bank and in associated National/State Parks and reserves. While simple density mapping revealed high value densities in various locations, it did not indicate what density of a landscape value could be regarded as a statistically significant hotspot or distinguish whether overlapping areas of high density for different values indicate identical or adjacent locations. A spatial statistic Getis-Ord Gi* was used to indicate statistically significant spatial clusters of high value densities or “hotspots”. Of 251 hotspots, 40% were for single non-use values, primarily spiritual, therapeutic or intrinsic. Four hotspots had 11 landscape values. Two, lacking economic value, were located in ecologically important river red gum forests and two, lacking wilderness value, were near the major towns of Echuca-Moama and Albury-Wodonga. Hotspots for eight values showed statistically significant associations with another value. There were high associations between learning and heritage values while economic and biological diversity values showed moderate associations with several other direct and indirect use values. This approach may improve confidence in the interpretation of spatial analysis of landscape values by enhancing understanding of value relationships.

Correlation between structure and compressive strength in a reticulated glass-reinforced hydroxyapatite foam.

PubMed

Callcut, S; Knowles, J C

2002-05-01

Glass-reinforced hydroxyapatite (HA) foams were produced using reticulated foam technology using a polyurethane template with two different pore size distributions. The mechanical properties were evaluated and the structure analyzed through density measurements, image analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM). For the mechanical properties, the use of a glass significantly improved the ultimate compressive strength (UCS) as did the use of a second coating. All the samples tested showed the classic three regions characteristic of an elastic brittle foam. From the density measurements, after application of a correction to compensate for the closed porosity, the bulk and apparent density showed a 1 : 1 correlation. When relative bulk density was plotted against UCS, a non-linear relationship was found characteristic of an isotropic open celled material. It was found by image analysis that the pore size distribution did not change and there was no degradation of the macrostructure when replicating the ceramic from the initial polyurethane template during processing. However, the pore size distributions did shift to a lower size by about 0.5 mm due to the firing process. The ceramic foams were found to exhibit mechanical properties typical of isotropic open cellular foams.

Amide I vibrational circular dichroism of dipeptide: Conformation dependence and fragment analysis

NASA Astrophysics Data System (ADS)

Choi, Jun-Ho; Cho, Minhaeng

2004-03-01

The amide I vibrational circular dichroic response of alanine dipeptide analog (ADA) was theoretically investigated and the density functional theory calculation and fragment analysis results are presented. A variety of vibrational spectroscopic properties, local and normal mode frequencies, coupling constant, dipole, and rotational strengths, are calculated by varying two dihedral angles determining the three-dimensional ADA conformation. Considering two monopeptide fragments separately, we show that the amide I vibrational circular dichroism of the ADA can be quantitatively predicted. For several representative conformations of the model ADA, vibrational circular dichroism spectra are calculated by using both the density functional theory calculation and fragment analysis methods.

Breast density in multiethnic women presenting for screening mammography.

PubMed

Oppong, Bridget A; Dash, Chiranjeev; O'Neill, Suzanne; Li, Yinan; Makambi, Kepher; Pien, Edward; Makariou, Erini; Coleman, Tesha; Adams-Campbell, Lucile L

2018-05-01

Data on ethnic variations in breast density are limited and often not inclusive of underrepresented minorities. As breast density is associated with elevated breast cancer risk, investigating racial and ethnic difference may elucidate the observed differences in breast cancer risk among different populations. We reviewed breast density from initial screening of women from the Capital Breast Care Center and Georgetown University Hospital from 2010 to 2014. Patient demographics including race, age at screening, education, menopausal status, and body mass index were abstracted. We recorded the BI-RADS density categories: (1) "fatty," (2) "scattered fibroglandular densities," (3) "heterogeneously dense," and (4) "extremely dense." Multivariable unconditional logistic regression was used to identify predictors of breast density. Density categorization was recorded for 2146 women over the 5-year period, comprising Blacks (n = 940), Hispanics (n = 893), and Whites (n = 314). Analysis of subject characteristics by breast density showed that high category is observed in younger, Hispanic, nulliparous, premenopausal, and nonobese women (t-test or chi-square test, P-values <.0001). Obese women are 70% less likely to have high density. Being Hispanic, premenopausal, and nonobese were predictive of high density on logistic regression. In this analysis of density distribution in a diverse sample, Hispanic women have the highest breast density, followed by Blacks and Whites. Unique in our findings is women who identify as Hispanic have the highest breast density and lower rates of obesity. Further investigation of the impact of obesity on breast density, especially in the understudied Hispanic group is needed. © 2017 Wiley Periodicals, Inc.

Vision 20/20: Mammographic breast density and its clinical applications

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

Ng, Kwan-Hoong, E-mail: ngkh@ummc.edu.my; Lau, Susie

2015-12-15

Breast density is a strong predictor of the failure of mammography screening to detect breast cancer and is a strong predictor of the risk of developing breast cancer. The many imaging options that are now available for imaging dense breasts show great promise, but there is still the question of determining which women are “dense” and what imaging modality is suitable for individual women. To date, mammographic breast density has been classified according to the Breast Imaging-Reporting and Data System (BI-RADS) categories from visual assessment, but this is known to be very subjective. Despite many research reports, the authors believemore » there has been a lack of physics-led and evidence-based arguments about what breast density actually is, how it should be measured, and how it should be used. In this paper, the authors attempt to start correcting this situation by reviewing the history of breast density research and the debates generated by the advocacy movement. The authors review the development of breast density estimation from pattern analysis to area-based analysis, and the current automated volumetric breast density (VBD) analysis. This is followed by a discussion on seeking the ground truth of VBD and mapping volumetric methods to BI-RADS density categories. The authors expect great improvement in VBD measurements that will satisfy the needs of radiologists, epidemiologists, surgeons, and physicists. The authors believe that they are now witnessing a paradigm shift toward personalized breast screening, which is going to see many more cancers being detected early, with the use of automated density measurement tools as an important component.« less

Understanding the conformational flexibility and electrostatic properties of curcumin in the active site of rhAChE via molecular docking, molecular dynamics, and charge density analysis.

PubMed

Saravanan, Kandasamy; Kalaiarasi, Chinnasamy; Kumaradhas, Poomani

2017-12-01

Acetylcholinesterase (AChE) is an important enzyme responsible for Alzheimer's disease, as per report, keto-enol form of curcumin inhibits this enzyme. The present study aims to understand the binding mechanism of keto-enol curcumin with the recombinant human Acetylcholinesterase (rhAChE) from its conformational flexibility, intermolecular interactions, charge density distribution, and the electrostatic properties at the active site of rhAChE. To accomplish this, a molecular docking analysis of curcumin with the rhAChE was performed, which gives the structure and conformation of curcumin in the active site of rhAChE. Further, the charge density distribution and the electrostatic properties of curcumin molecule (lifted from the active site of rhAChE) were determined from the high level density functional theory (DFT) calculations coupled with the charge density analysis. On the other hand, the curcumin molecule was optimized (gas phase) using DFT method and further, the structure and charge density analysis were also carried out. On comparing the conformation, charge density distribution and the electrostatic potential of the active site form of curcumin with the corresponding gas phase form reveals that the above said properties are significantly altered when curcumin is present in the active site of rhAChE. The conformational stability and the interaction of curcumin in the active site are also studied using molecular dynamics simulation, which shows a large variation in the conformational geometry of curcumin as well as the intermolecular interactions.

Evaluation of the Effect of Light and Scanning Time Delay on The Image Quality of Intra Oral Photostimulable Phosphor Plates

PubMed Central

Eskandarloo, Amir; Yousefi, Arman; Soheili, Setareh; Ghazikhanloo, Karim; Amini, Payam; Mohammadpoor, Haniyeh

2017-01-01

Background: Nowadays, digital radiography is widely used in dental practice. One of the most common types is Photo Stimulated Phosphor Plate (PSP). Objective: The aims of this experimental study were to evaluate the impacts of different combinations of storage conditions and varying delays in reading of digital images captured using PSPs. Methods: Standardized images of a step wedges were obtained using PSPs from the Digora digital systems. Plates were exposed and immediately scanned to produce the baseline gold standard. The plates were re-exposed and stored in four different storage conditions: white light, yellow light, natural light environment and dark room, then scanned after 10 and 30 minutes and 4 and 8 hours. Objective analysis was conducted by density measurements and the data were analyzed statistically using GEE test. Subjective analysis was performed by two oral and maxillofacial radiologists and the results were analyzed using McNemar’s test. Results: The results from GEE analysis show that in the natural light environment, the densities in 10 minutes did not differ from the baseline. The mean densities decreased significantly during the time in all environments. The mean densities in step 2 for the dark room environment decreased with a slighter slope in comparison to yellow environment significantly. Conclusion: PSP images showed significant decrease in the density in plates scanned for 10 minutes or longer after exposure which may not be detected clinically. The yellow light environment had a different impact on the quality of PSP images. The spatial resolution did not change significantly with time. PMID:29430262

Evaluation of the Effect of Light and Scanning Time Delay on The Image Quality of Intra Oral Photostimulable Phosphor Plates.

PubMed

Eskandarloo, Amir; Yousefi, Arman; Soheili, Setareh; Ghazikhanloo, Karim; Amini, Payam; Mohammadpoor, Haniyeh

2017-01-01

Nowadays, digital radiography is widely used in dental practice. One of the most common types is Photo Stimulated Phosphor Plate (PSP). The aims of this experimental study were to evaluate the impacts of different combinations of storage conditions and varying delays in reading of digital images captured using PSPs. Standardized images of a step wedges were obtained using PSPs from the Digora digital systems. Plates were exposed and immediately scanned to produce the baseline gold standard. The plates were re-exposed and stored in four different storage conditions: white light, yellow light, natural light environment and dark room, then scanned after 10 and 30 minutes and 4 and 8 hours. Objective analysis was conducted by density measurements and the data were analyzed statistically using GEE test. Subjective analysis was performed by two oral and maxillofacial radiologists and the results were analyzed using McNemar's test. The results from GEE analysis show that in the natural light environment, the densities in 10 minutes did not differ from the baseline. The mean densities decreased significantly during the time in all environments. The mean densities in step 2 for the dark room environment decreased with a slighter slope in comparison to yellow environment significantly. PSP images showed significant decrease in the density in plates scanned for 10 minutes or longer after exposure which may not be detected clinically. The yellow light environment had a different impact on the quality of PSP images. The spatial resolution did not change significantly with time.

Electronic and optical properties of nanocrystalline WO3 thin films studied by optical spectroscopy and density functional calculations

NASA Astrophysics Data System (ADS)

Johansson, Malin B.; Baldissera, Gustavo; Valyukh, Iryna; Persson, Clas; Arwin, Hans; Niklasson, Gunnar A.; Österlund, Lars

2013-05-01

The optical and electronic properties of nanocrystalline WO3 thin films prepared by reactive dc magnetron sputtering at different total pressures (Ptot) were studied by optical spectroscopy and density functional theory (DFT) calculations. Monoclinic films prepared at low Ptot show absorption in the near infrared due to polarons, which is attributed to a strained film structure. Analysis of the optical data yields band-gap energies Eg ≈ 3.1 eV, which increase with increasing Ptot by 0.1 eV, and correlate with the structural modifications of the films. The electronic structures of triclinic δ-WO3, and monoclinic γ- and ε-WO3 were calculated using the Green function with screened Coulomb interaction (GW approach), and the local density approximation. The δ-WO3 and γ-WO3 phases are found to have very similar electronic properties, with weak dispersion of the valence and conduction bands, consistent with a direct band-gap. Analysis of the joint density of states shows that the optical absorption around the band edge is composed of contributions from forbidden transitions (>3 eV) and allowed transitions (>3.8 eV). The calculations show that Eg in ε-WO3 is higher than in the δ-WO3 and γ-WO3 phases, which provides an explanation for the Ptot dependence of the optical data.

Social deprivation and population density are not associated with small area risk of amyotrophic lateral sclerosis.

PubMed

Rooney, James P K; Tobin, Katy; Crampsie, Arlene; Vajda, Alice; Heverin, Mark; McLaughlin, Russell; Staines, Anthony; Hardiman, Orla

2015-10-01

Evidence of an association between areal ALS risk and population density has been previously reported. We aim to examine ALS spatial incidence in Ireland using small areas, to compare this analysis with our previous analysis of larger areas and to examine the associations between population density, social deprivation and ALS incidence. Residential area social deprivation has not been previously investigated as a risk factor for ALS. Using the Irish ALS register, we included all cases of ALS diagnosed in Ireland from 1995-2013. 2006 census data was used to calculate age and sex standardised expected cases per small area. Social deprivation was assessed using the pobalHP deprivation index. Bayesian smoothing was used to calculate small area relative risk for ALS, whilst cluster analysis was performed using SaTScan. The effects of population density and social deprivation were tested in two ways: (1) as covariates in the Bayesian spatial model; (2) via post-Bayesian regression. 1701 cases were included. Bayesian smoothed maps of relative risk at small area resolution matched closely to our previous analysis at a larger area resolution. Cluster analysis identified two areas of significant low risk. These areas did not correlate with population density or social deprivation indices. Two areas showing low frequency of ALS have been identified in the Republic of Ireland. These areas do not correlate with population density or residential area social deprivation, indicating that other reasons, such as genetic admixture may account for the observed findings. Copyright © 2015 Elsevier Inc. All rights reserved.

Extended analytical solutions for effective elastic moduli of cracked porous media

NASA Astrophysics Data System (ADS)

Nguyen, Sy-Tuan; To, Quy Dong; Vu, Minh Ngoc

2017-05-01

Extended solutions are derived, on the basis of the micromechanical methods, for the effective elastic moduli of porous media containing stiff pores and both open and closed cracks. Analytical formulas of the overall bulk and shear moduli are obtained as functions of the elastic moduli of the solid skeleton, porosity and the densities of open and closed cracks families. We show that the obtained results are extensions of the classical widely used Walsh's (JGR, 1965) and Budiansky-O‧Connell's (JGR, 1974) solutions. Parametric sensitivity analysis clarifies the impact of the model parameters on the effective elastic properties. An inverse analysis, using sonic and density data, is considered to quantify the density of both open and closed cracks. It is observed that the density of closed cracks depends strongly on stress condition while the dependence of open cracks on the confining stress is negligible.

Direct numerical simulation of axisymmetric laminar low-density jets

NASA Astrophysics Data System (ADS)

Gomez Lendinez, Daniel; Coenen, Wilfried; Sevilla, Alejandro

2017-11-01

The stability of submerged laminar axisymmetric low-density jets has been investigated experimentally (Kyle & Sreenivasan 1993, Hallberg & Strykowski 2006) and with linear analysis (Jendoubi & Strykowski 1994, Coenen & Sevilla 2012, Coenen et al. 2017). These jets become globally unstable when the Reynolds number is larger than a certain critical value which depends on the density ratio and on the velocity profile at the injector outlet. In this work, Direct Numerical Simulations using FreeFEM + + (Hecht 2012) with P1 elements for pressure and P2 for velocity and density are performed to complement the above mentioned studies. Density and velocity fields are analyzed at long time showing the unforced space-time evolution of nonlinear disturbances propagating along the jet. Using the Stuart-Landau model to fit the numerical results for the self-excited oscillations we have computed a neutral stability curve that shows good agreement with experiments and stability theory. Thanks to Spanish MINECO under projects DPI2014-59292-C3-1-P and DPI2015-71901-REDT for financial support.

[Correlative factors related to the density of Meriones unguiculatus in the Meriones unguiculatus plague foci of Hebei province, 2001-2013].

PubMed

Niu, Y F; Kang, X P; Yan, D; Zhang, Y H; Liu, G; Kang, D M; Liu, H Z; Shi, X M; Li, Y G

2016-08-10

To explore the yearly, monthly and habitat-related distribution and their relations with Meriones unguiculatus density in the Hebei Meriones unguiculatus plague foci, from 2001 to 2013. Data related to Meriones unguiculatus was gathered through the monitoring programs set up at the national and provincial Meriones unguiculatus plague foci in Hebei province, from 2001 to 2013. According to the yearly density of Meriones unguiculatus, criteria set for the three groups under study, were as follows:'high-risk group'-when the rodent density was≥1.00 under rodents/hm(2),'warning group'-when the rodents/hm(2)>rodent density> 0.20,'standard group'-when rodents/hm(2) rodent density≤0.20 rodents/hm(2). Differences of habitats and monthly distribution among the three groups were compared, under the Kruskal-Wallis H rank sum test while their relations were under the multiple correspondence analysis. The Meriones unguiculatus densities were higher than 1.00 rodents/hm(2), far above the set national standards, in the monitoring area, between 2001 and 2005. From 2005, though the rodent densities began to decrease, however, figures from 2008 to 2013 were still among 0.20 to 1.00 rodents/hm(2). The distribution of habitats in the three groups showed that the Meriones unguiculatus densities were all different in habitats and the difference was statistically significant (P<0.05). The highest median densities were all in the arable land, with maximum value of high-risk group appeared the highest (20.50 rodents/hm(2)) in the wasteland. Monthly distribution showed that the Meriones unguiculatus densities were different and the difference was statistically significant (P<0.05) in the high-risk and standard groups but not statistically significant in the warning group. Data from the multiple correspondence analysis showed that there was a strong aggregation among wasteland, in April and June, while the warning group was associated with weather in July and the arable land. When the density became higher than 1.00 rodents/hm(2), the risk on animal plague increased in Hebei Meriones unguiculatus plague foci. Based on the distribution of Meriones unguiculatus, programs should be set to monitor the rodent in arable land and wasteland, in April and June, to reduce the prevalence of animals plague.

Bioelectricity generation in microbial fuel cell using natural microflora and isolated pure culture bacteria from anaerobic palm oil mill effluent sludge.

PubMed

Nor, Muhamad Hanif Md; Mubarak, Mohd Fahmi Muhammad; Elmi, Hassan Sh Abdirahman; Ibrahim, Norahim; Wahab, Mohd Firdaus Abdul; Ibrahim, Zaharah

2015-08-01

A double-chambered membrane microbial fuel cell (MFC) was constructed to investigate the potential use of natural microflora anaerobic palm oil mill effluent (POME) sludge and pure culture bacteria isolated from anaerobic POME sludge as inoculum for electricity generation. Sterilized final discharge POME was used as the substrate with no addition of nutrients. MFC operation using natural microflora anaerobic POME sludge showed a maximum power density and current density of 85.11mW/m(2) and 91.12mA/m(2) respectively. Bacterial identification using 16S rRNA analysis of the pure culture isolated from the biofilm on the anode MFC was identified as Pseudomonas aeruginosa strain ZH1. The electricity generated in MFC using P. aeruginosa strain ZH1 showed maximum power density and current density of 451.26mW/m(2) and 654.90mA/m(2) respectively which were five times higher in power density and seven times higher in current density compared to that of MFC using anaerobic POME sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.

Low-Density Nozzle Flow by the Direct Simulation Monte Carlo and Continuum Methods

NASA Technical Reports Server (NTRS)

Chung, Chang-Hong; Kim, Sku C.; Stubbs, Robert M.; Dewitt, Kenneth J.

1994-01-01

Two different approaches, the direct simulation Monte Carlo (DSMC) method based on molecular gasdynamics, and a finite-volume approximation of the Navier-Stokes equations, which are based on continuum gasdynamics, are employed in the analysis of a low-density gas flow in a small converging-diverging nozzle. The fluid experiences various kinds of flow regimes including continuum, slip, transition, and free-molecular. Results from the two numerical methods are compared with Rothe's experimental data, in which density and rotational temperature variations along the centerline and at various locations inside a low-density nozzle were measured by the electron-beam fluorescence technique. The continuum approach showed good agreement with the experimental data as far as density is concerned. The results from the DSMC method showed good agreement with the experimental data, both in the density and the rotational temperature. It is also shown that the simulation parameters, such as the gas/surface interaction model, the energy exchange model between rotational and translational modes, and the viscosity-temperature exponent, have substantial effects on the results of the DSMC method.

Dynamics and density distributions in a capillary-discharge waveguide with an embedded supersonic jet

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

Matlis, N. H., E-mail: nmatlis@gmail.com; Gonsalves, A. J.; Steinke, S.

We present an analysis of the gas dynamics and density distributions within a capillary-discharge waveguide with an embedded supersonic jet. This device provides a target for a laser plasma accelerator which uses longitudinal structuring of the gas-density profile to enable control of electron trapping and acceleration. The functionality of the device depends sensitively on the details of the density profile, which are determined by the interaction between the pulsed gas in the jet and the continuously-flowing gas in the capillary. These dynamics are captured by spatially resolving recombination light from several emission lines of the plasma as a function ofmore » the delay between the jet and the discharge. We provide a phenomenological description of the gas dynamics as well as a quantitative evaluation of the density evolution. In particular, we show that the pressure difference between the jet and the capillary defines three regimes of operation with qualitatively different longitudinal density profiles and show that jet timing provides a sensitive method for tuning between these regimes.« less

The importance of bulk density determination in gravity data processing for structure interpretation

NASA Astrophysics Data System (ADS)

Wildan, D.; Akbar, A. M.; Novranza, K. M. S.; Sobirin, R.; Permadi, A. N.; Supriyanto

2017-07-01

Gravity method use rock density variation for determining subsurface lithology and geological structure. In the "green area" where measurement of rock density has not been done, an attemp to find density is usually performed by calculating using Parasnis method, or by using using the average of rock density in the earth's crust (2,67 gr/cm3) or by using theoritical value of dominant rock density in the survey area (2,90 gr/cm3). Those three values of densities are applied to gravity data analysis in the hilly "X" area. And we have compared all together in order to observed which value has represented the structure better. The result showed that the higher value of rock density, the more obvious structure in the Bouguer anomaly profile. It is due to the contrast of maximum and minimum value of Bouguer anomaly that will affect the exageration in distance vs Bouguer anomaly graphic.

Flux pinning enhancement in thin films of Y3 Ba5 Cu8O18.5 + d

NASA Astrophysics Data System (ADS)

Aghabagheri, S.; Mohammadizadeh, M. R.; Kameli, P.; Salamati, H.

2018-06-01

YBa2Cu3O7 (Y123) and Y3Ba5Cu8O18 (Y358) thin films were deposited by pulsed laser deposition method. XRD analysis shows both films grow in c axis orientation. Resistivity versus temperature analysis shows superconducting transition temperature was about 91.2 K and 91.5 K and transition width for Y358 and Y123 films was about 0.6 K and 1.6 K, respectively. Analysis of the temperature dependence of the AC susceptibility near the transition temperature, employing Bean's critical state model, indicates that intergranular critical current density for Y358 films is more than twice of intergranular critical current density of Y123 films. Thus, flux pining is stronger in Y358 films. Weak links in the both samples is of superconductor-normal-superconductor (SNS) type irrespective of stoichiometry.

Analysis of Crystallographic Structure of a Japanese Sword by the Pulsed Neutron Transmission Method

NASA Astrophysics Data System (ADS)

Kino, K.; Ayukawa, N.; Kiyanagi, Y.; Uchida, T.; Uno, S.; Grazzi, F.; Scherillo, A.

We measured two-dimensional transmission spectra of pulsed neutron beams for a Japanese sword sample. Atom density, crystalline size, and preferred orientation of crystals were obtained using the RITS code. The position dependence of the atomic density is consistent with the shape of the sample. The crystalline size is very small and shows position dependence, which is understood by the unique structure of Japanese swords. The preferred orientation has strong position dependence. Our study shows the usefulness of the pulsed neutron transmission method for cultural metal artifacts.

Rhodium clustering process on defective (8,0) SWCNT: Analysis of chemical and physical properties using density functional theory

NASA Astrophysics Data System (ADS)

Ambrusi, Ruben E.; Luna, C. Romina; Sandoval, Mario G.; Bechthold, Pablo; Pronsato, M. Estela; Juan, Alfredo

2017-12-01

The Spin-polarized density functional theory is used to study the effect of a single vacancy in a (8,0) single-walled carbon nanotube (SWCNT) on the Rh clustering process. The vacancy is considered oxygenated and non-oxygenated and, in each case, different Rhn cluster sizes (n = 1-4) are taken into account. For the analysis of these systems some physical and chemical properties are calculated, such as binding energy (Eb), work function (WF), magnetic moment, charge transfer, bond length, band gap (Eg), and density of state (DOS). From this analysis it can be concluded that: a single Rh atom and Rh2 dimer are adsorbed on vacancy without oxygen, whereas Rh3 and Rh4 clusters prefer to be adsorbed on oxygenated vacancy. In all cases, Rh adsorption induces a magnetic moment. When the Rh atom and Rh2 dimer are bonded to the defective SWCNT, it has been found that they show a semiconductor behavior that could be interesting to use in the spintronic area. In the case of Rh3 and Rh4 clusters our results show a metallic behavior suggesting that these systems are good candidates for nanotube contact.

Changes of buoyant density during the S-phase of the cell cycle. Direct evidence demonstrated in acute myeloid leukemia by flowcytometry.

PubMed

Daenen, S; Huiges, W; Modderman, E; Halie, M R

1993-01-01

Studies with synchronized or exponentially growing bacteria and mammalian cell lines are not able to demonstrate small changes in buoyant density during the cell cycle. Flowcytometric analysis of density separated acute myeloid leukemia cells, a system not dependent on time-related variables, shows that the cellular buoyant density increases slightly with up to 0.008 g/ml during the S-phase, at least in cryo-preserved cells used in this study. This contrasts with the generally accepted belief that S-phase cells have a lower or constant buoyant density. A practical implication is that separation of cell (sub)populations based on differences in buoyant density could be flawed to the extent that these populations contain S-phase cells.

Quantifying Mold Biomass on Gypsum Board: Comparison of Ergosterol and Beta-N-Acetylhexosaminidase as Mold Biomass Parameters

PubMed Central

Reeslev, M.; Miller, M.; Nielsen, K. F.

2003-01-01

Two mold species, Stachybotrys chartarum and Aspergillus versicolor, were inoculated onto agar overlaid with cellophane, allowing determination of a direct measurement of biomass density by weighing. Biomass density, ergosterol content, and beta-N-acetylhexosaminidase (3.2.1.52) activity were monitored from inoculation to stationary phase. Regression analysis showed a good linear correlation to biomass density for both ergosterol content and beta-N-acetylhexosaminidase activity. The same two mold species were inoculated onto wallpapered gypsum board, from which a direct biomass measurement was not possible. Growth was measured as an increase in ergosterol content and beta-N-acetylhexosaminidase activity. A good linear correlation was seen between ergosterol content and beta-N-acetylhexosaminidase activity. From the experiments performed on agar medium, conversion factors (CFs) for estimating biomass density from ergosterol content and beta-N-acetylhexosaminidase activity were determined. The CFs were used to estimate the biomass density of the molds grown on gypsum board. The biomass densities estimated from ergosterol content and beta-N-acetylhexosaminidase activity data gave similar results, showing significantly slower growth and lower stationary-phase biomass density on gypsum board than on agar. PMID:12839773

Using Data Pooling to Measure the Density of Sodas: An Introductory Discovery Experiment

NASA Astrophysics Data System (ADS)

Herrick, Richard S.; Nestor, Lisa P.; Benedetto, David A.

1999-10-01

We have developed an experiment in which students measure the density of Coke and Diet Coke. In the first part of the experiment they make measurements using a buret, pipet, and graduated cylinder. The density data are pooled and plotted for each type of glassware. Students discover that Coke and Diet Coke have different densities. Discussion of the data also shows students the relative advantages and disadvantages of each type of apparatus and introduces them to the concept of error analysis. In the second half of the experiment each student uses a buret to accurately measure an assigned volume of either Coke or Diet Coke. Volumes in the range of 2 to 30 mL are assigned. These data are pooled. The slope of the mass-vs-volume plot provides an accurate measurement of the density and also shows that density is an intensive property. The difference in densities is due to the large amount of sugar in Coke compared to the relatively small amount of artificial sweetener in Diet Coke. Information read from soda cans is used to estimate the accuracy of these measurements. This experiment is used as the first experiment for college science students.

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

Akkelin, S.V.; Sinyukov, Yu.M.

A method allowing analysis of the overpopulation of phase space in heavy ion collisions in a model-independent way is proposed within the hydrodynamic approach. It makes it possible to extract a chemical potential of thermal pions at freeze-out, irrespective of the form of freeze-out (isothermal) hypersurface in Minkowski space and transverse flows on it. The contributions of resonance (with masses up to 2 GeV) decays to spectra, interferometry volumes, and phase-space densities are calculated and discussed in detail. The estimates of average phase-space densities and chemical potentials of thermal pions are obtained for SPS and RHIC energies. They demonstrate thatmore » multibosonic phenomena at those energies might be considered as a correction factor rather than as a significant physical effect. The analysis of the evolution of the pion average phase-space density in chemically frozen hadron systems shows that it is almost constant or slightly increases with time while the particle density and phase-space density at each space point decreases rapidly during the system's expansion. We found that, unlike the particle density, the average phase-space density has no direct link to the freeze-out criterion and final thermodynamic parameters, being connected rather to the initial phase-space density of hadronic matter formed in relativistic nucleus-nucleus collisions.« less

Vibrational spectroscopic investigation and normal coordinate analysis of the fibrate hypolipidemic agent 5-(2,5-dimethylphenoxy)-2,2-dimethyl pentanoic acid (Gemfibrozil)

NASA Astrophysics Data System (ADS)

Priya, M. Siva; Benitta, T. Asenath; James, C.

2011-03-01

Colorless crystals of 5-(2,5-dimethylphenoxy)-2,2-dimethyl pentanoic acid were grown by slow evaporation method and the FT-IR and FT-Raman spectra of the sample were recorded in the region 4000-450 cm -1 and 4000-50 cm -1 respectively. Molecular structure is optimized with the help of B3LYP/6-31G (d) density functional theory method. Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the σ ∗ antibonding orbitals and E (2) energies confirms the occurrence of intra-molecular charge transfer (ICT) within the molecule. The assignments of the vibrational spectra have been carried out with the help of Normal coordinate analysis following the scaled quantum mechanical force field (SQMFF) methodology. Mulliken population analysis on atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule.

A quantum molecular similarity analysis of changes in molecular electron density caused by basis set flotation and electric field application

NASA Astrophysics Data System (ADS)

Simon, Sílvia; Duran, Miquel

1997-08-01

Quantum molecular similarity (QMS) techniques are used to assess the response of the electron density of various small molecules to application of a static, uniform electric field. Likewise, QMS is used to analyze the changes in electron density generated by the process of floating a basis set. The results obtained show an interrelation between the floating process, the optimum geometry, and the presence of an external field. Cases involving the Le Chatelier principle are discussed, and an insight on the changes of bond critical point properties, self-similarity values and density differences is performed.

Nature of non-nuclear (3, -3) π-attractor and π-bonding: Theoretical analysis on π-electron density

NASA Astrophysics Data System (ADS)

Lv, Jiao; Yang, Lihua; Sun, Zheng; Meng, Lingpeng; Li, Xiaoyan

2018-01-01

Understanding the nature of π-electron density is important to characterize the conjugate π molecular systems. In this work, the π-electron densities of some typical conjugated π molecular systems were separated from their total electron densities; the positions and natures of non-nuclear (3, -3) π-attractors and the π-bond critical points (π-BCPs) are investigated. The calculated results show that for the same element, the position of the π-attractor is constant, regardless of the chemical surroundings. The position of the π-BCP is closer to the atom with the larger electronegativity.

Measuring treatment response to systemic therapy and predicting outcome in biliary tract cancer: comparing tumor size, volume, density, and metabolism.

PubMed

Sahani, Dushyant V; Hayano, Koichi; Galluzzo, Anna; Zhu, Andrew X

2015-04-01

The purpose of this study was to evaluate the response of biliary tract cancer treated with multidrug chemotherapy using FDG PET in comparison with morphologic and density changes. In this phase II clinical trial, 28 patients with unresectable or metastatic biliary tract cancers treated with gemcitabine and oxaliplatin combined with bevacizumab (GEMOX-B) underwent FDG PET and contrast-enhanced CT at baseline and after the second cycle of the therapy (8 weeks). A single reviewer recorded tumor maximum standardized uptake value (SUVmax) along with size, volume (3D-sphere), and density. The percentage changes of the parameters were compared with progression-free survival at 7 months. Overall survival was compared with the percentage change of SUVmax. After 8 weeks, measurable reductions (±SD) in size (7.05±4.19 to 5.52±3.28 cm, -21.70%), volume (411.38±540.08 to 212.41±293.45 cm3, -48.36%), and density (60.76±20.65 to 50.68±16.89 HU, -15.59%) were noted along with a substantial drop in SUVmax (5.95±1.95 to 3.36±1.28, -43.52%). The SUVmax change showed positive correlations with tumor size change (R2=0.39, p=0.0004) and volumetric change (R2=0.34, p=0.001). Patients who showed a larger drop in SUVmax at 8 weeks correlated with favorable progression-free survival (p=0.02). ROC analysis showed that a 45% reduction in SUVmax was the best cutoff value to detect favorable progression-free survival patients. When we used this cutoff value, Kaplan-Meier analysis showed that patients with tumors showing greater reduction in SUVmax had favorable progression-free survival and overall survival (p=0.0009, p=0.03). In biliary tract cancers treated with GEMOX-B, the reduction of SUVmax after therapy is a better predictor for survival than morphologic and density changes.

Thermal Performance of Cryogenic Multilayer Insulation at Various Layer Spacings

NASA Technical Reports Server (NTRS)

Johnson, Wesley Louis

2010-01-01

Multilayer insulation (MLI) has been shown to be the best performing cryogenic insulation system at high vacuum (less that 10 (exp 3) torr), and is widely used on spaceflight vehicles. Over the past 50 years, many investigations into MLI have yielded a general understanding of the many variables that are associated with MLI. MLI has been shown to be a function of variables such as warm boundary temperature, the number of reflector layers, and the spacer material in between reflectors, the interstitial gas pressure and the interstitial gas. Since the conduction between reflectors increases with the thickness of the spacer material, yet the radiation heat transfer is inversely proportional to the number of layers, it stands to reason that the thermal performance of MLI is a function of the number of layers per thickness, or layer density. Empirical equations that were derived based on some of the early tests showed that the conduction term was proportional to the layer density to a power. This power depended on the material combination and was determined by empirical test data. Many authors have graphically shown such optimal layer density, but none have provided any data at such low densities, or any method of determining this density. Keller, Cunnington, and Glassford showed MLI thermal performance as a function of layer density of high layer densities, but they didn't show a minimal layer density or any data below the supposed optimal layer density. However, it was recently discovered that by manipulating the derived empirical equations and taking a derivative with respect to layer density yields a solution for on optimal layer density. Various manufacturers have begun manufacturing MLI at densities below the optimal density. They began this based on the theory that increasing the distance between layers lowered the conductive heat transfer and they had no limitations on volume. By modifying the circumference of these blankets, the layer density can easily be varied. The simplest method of determining the thermal performance of MLI at cryogenic temperature is by boil-off calorimetry. Several blankets were procured and tested at various layer densities at the Cryogenics Test Laboratory at Kennedy Space Center. The densities that the blankets were tested over covered a wide range of layer densities including the analytical minimum. Several of the blankets were tested at the same insulation thickness while changing the layer density (thus a different number of reflector layers). Optimizing the layer density of multilayer insulation systems for heat transfer would remove a layer density from the complex method of designing such insulation systems. Additional testing was performed at various warm boundary temperatures and pressures. The testing and analysis was performed to simplify the analysis of cryogenic thermal insulation systems. This research was funded by the National Aeronautics and Space Administration's Exploration Technology Development Program's Cryogenic Fluid Management Project

Miscible gravitational instability of initially stable horizontal interface in a porous medium: Non-monotonic density profiles

NASA Astrophysics Data System (ADS)

Kim, Min Chan

2014-11-01

To simulate a CO2 sequestration process, some researchers employed a water/propylene glycol (PPG) system which shows a non-monotonic density profile. Motivated by this fact, the stability of the diffusion layer of two miscible fluids saturated in a porous medium is analyzed. For a non-monotonic density profile system, linear stability equations are derived in a global domain, and then transformed into a system of ordinary differential equations in an infinite domain. Initial growth rate analysis is conducted without the quasi-steady state approximation (QSSA) and shows that initially the system is unconditionally stable for the least stable disturbance. For the time evolving case, the ordinary differential equations are solved applying the eigen-analysis and numerical shooting scheme with and without the QSSA. To support these theoretical results, direct numerical simulations are conducted using the Fourier spectral method. The results of theoretical linear stability analyses and numerical simulations validate one another. The present linear and nonlinear analyses show that the water/PPG system is more unstable than the CO2/brine one, and the flow characteristics of these two systems are quite different from each other.

Correlation Between Bone Density and Instantaneous Torque at Implant Site Preparation: A Validation on Polyurethane Foam Blocks of a Device Assessing Density of Jawbones.

PubMed

Di Stefano, Danilo Alessio; Arosio, Paolo

2016-01-01

Bone density at implant placement sites is one of the key factors affecting implant primary stability, which is a determinant for implant osseointegration and rehabilitation success. Site-specific bone density assessment is, therefore, of paramount importance. Recently, an implant micromotor endowed with an instantaneous torque-measuring system has been introduced. The aim of this study was to assess the reliability of this system. Five blocks with different densities (0.16, 0.26, 0.33, 0.49, and 0.65 g/cm(3)) were used. A single trained operator measured the density of one of them (0.33 g/cm(3)), by means of five different devices (20 measurements/device). The five resulting datasets were analyzed through the analysis of variance (ANOVA) model to investigate interdevice variability. As differences were not significant (P = .41), the five devices were each assigned to a different operator, who collected 20 density measurements for each block, both under irrigation (I) and without irrigation (NI). Measurements were pooled and averaged for each block, and their correlation with the actual block-density values was investigated using linear regression analysis. The possible effect of irrigation on density measurement was additionally assessed. Different devices provided reproducible, homogenous results. No significant interoperator variability was observed. Within the physiologic range of densities (> 0.30 g/cm(3)), the linear regression analysis showed a significant linear correlation between the mean torque measurements and the actual bone densities under both drilling conditions (r = 0.990 [I], r = 0.999 [NI]). Calibration lines were drawn under both conditions. Values collected under irrigation were lower than those collected without irrigation at all densities. The NI/I mean torque ratio was shown to decrease linearly with density (r = 0.998). The mean error introduced by the device-operator system was less than 10% in the range of normal jawbone density. Measurements performed with the device were linearly correlated with the blocks' bone densities. The results validate the device as an objective intraoperative tool for bone-density assessment that may contribute to proper jawbone-density evaluation and implant-insertion planning.

Development of Cell Analysis Software for Cultivated Corneal Endothelial Cells.

PubMed

Okumura, Naoki; Ishida, Naoya; Kakutani, Kazuya; Hongo, Akane; Hiwa, Satoru; Hiroyasu, Tomoyuki; Koizumi, Noriko

2017-11-01

To develop analysis software for cultured human corneal endothelial cells (HCECs). Software was designed to recognize cell borders and to provide parameters such as cell density, coefficient of variation, and polygonality of cultured HCECs based on phase contrast images. Cultured HCECs with high or low cell density were incubated with Ca-free and Mg-free phosphate-buffered saline for 10 minutes to reveal the cell borders and were then analyzed with software (n = 50). Phase contrast images showed that cell borders were not distinctly outlined, but these borders became more distinctly outlined after phosphate-buffered saline treatment and were recognized by cell analysis software. The cell density value provided by software was similar to that obtained using manual cell counting by an experienced researcher. Morphometric parameters, such as the coefficient of variation and polygonality, were also produced by software, and these values were significantly correlated with cell density (Pearson correlation coefficients -0.62 and 0.63, respectively). The software described here provides morphometric information from phase contrast images, and it enables subjective and noninvasive quality assessment for tissue engineering therapy of the corneal endothelium.

Joint small-angle X-ray and neutron scattering data analysis of asymmetric lipid vesicles

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

Eicher, Barbara; Heberle, Frederick A.; Marquardt, Drew T.

2017-02-28

Low- and high-resolution models describing the internal transbilayer structure of asymmetric lipid vesicles have been developed. These models can be used for the joint analysis of small-angle neutron and X-ray scattering data. The models describe the underlying scattering length density/electron density profiles either in terms of slabs or through the so-called scattering density profile, previously applied to symmetric lipid vesicles. Both models yield structural details of asymmetric membranes, such as the individual area per lipid, and the hydrocarbon thickness of the inner and outer bilayer leaflets. The scattering density profile model, however, comes at a cost of increased computational effortmore » but results in greater structural resolution, showing a slightly lower packing of lipids in the outer bilayer leaflet of ~120 nm diameter palmitoyloleoyl phosphatidylcholine (POPC) vesicles, compared to the inner leaflet. Here, analysis of asymmetric dipalmitoyl phosphatidylcholine/POPC vesicles did not reveal evidence of transbilayer coupling between the inner and outer leaflets at 323 K, i.e.above the melting transition temperature of the two lipids.« less

Performance analysis of a brushless dc motor due to magnetization distribution in a continuous ring magnet

NASA Astrophysics Data System (ADS)

Hur, Jin; Jung, In-Soung; Sung, Ha-Gyeong; Park, Soon-Sup

2003-05-01

This paper represents the force performance of a brushless dc motor with a continuous ring-type permanent magnet (PM), considering its magnetization patterns: trapezoidal, trapezoidal with dead zone, and unbalanced trapezoidal magnetization with dead zone. The radial force density in PM motor causes vibration, because vibration is induced the traveling force from the rotating PM acting on the stator. Magnetization distribution of the PM as well as the shape of the teeth determines the distribution of force density. In particular, the distribution has a three-dimensional (3-D) pattern because of overhang, that is, it is not uniform in axial direction. Thus, the analysis of radial force density required dynamic analysis considering the 3-D shape of the teeth and overhang. The results show that the force density as a source of vibration varies considerably depending on the overhang and magnetization distribution patterns. In addition, the validity of the developed method, coupled 3-D equivalent magnetic circuit network method, with driving circuit and motion equation, is confirmed by comparison of conventional method using 3D finite element method.

Variation in the Prediction of Cross-Cultural Adjustment by Ethnic Density: A Longitudinal Study of Taiwanese Students in the United States

ERIC Educational Resources Information Center

Ying, Yu-Wen; Han, Meekyung

2008-01-01

The study examined variation in the prediction of adjustment in Taiwanese students by ethnic density. A total of 155 Taiwanese students were assessed via survey pre-departure and three times post-arrival in the United States. Hierarchical regression analysis showed students on campuses with fewer other Taiwanese peers formed more friendships with…

Analysis of rapid increase in the plasma density during the ramp-up phase in a radio frequency negative ion source by large-scale particle simulation

NASA Astrophysics Data System (ADS)

Yasumoto, M.; Ohta, M.; Kawamura, Y.; Hatayama, A.

2014-02-01

Numerical simulations become useful for the developing RF-ICP (Radio Frequency Inductively Coupled Plasma) negative ion sources. We are developing and parallelizing a two-dimensional three velocity electromagnetic Particle-In-Cell code. The result shows rapid increase in the electron density during the density ramp-up phase. A radial electric field due to the space charge is produced with increase in the electron density and the electron transport in the radial direction is suppressed. As a result, electrons stay for a long period in the region where the inductive electric field is strong, and this leads efficient electron acceleration and a rapid increasing of the electron density.

Non-Born-Oppenheimer electronic and nuclear densities for a Hooke-Calogero three-particle model: non-uniqueness of density-derived molecular structure.

PubMed

Ludeña, E V; Echevarría, L; Lopez, X; Ugalde, J M

2012-02-28

We consider the calculation of non-Born-Oppenheimer, nBO, one-particle densities for both electrons and nuclei. We show that the nBO one-particle densities evaluated in terms of translationally invariant coordinates are independent of the wavefunction describing the motion of center of mass of the whole system. We show that they depend, however, on an arbitrary reference point from which the positions of the vectors labeling the particles are determined. We examine the effect that this arbitrary choice has on the topology of the one-particle density by selecting the Hooke-Calogero model of a three-body system for which expressions for the one-particle densities can be readily obtained in analytic form. We extend this analysis to the one-particle densities obtained from full Coulomb interaction wavefunctions for three-body systems. We conclude, in view of the fact that there is a close link between the choice of the reference point and the topology of one-particle densities that the molecular structure inferred from the topology of these densities is not unique. We analyze the behavior of one-particle densities for the Hooke-Calogero Born-Oppenheimer, BO, wavefunction and show that topological transitions are also present in this case for a particular mass value of the light particles even though in the BO regime the nuclear masses are infinite. In this vein, we argue that the change in topology caused by variation of the mass ratio between light and heavy particles does not constitute a true indication in the nBO regime of the emergence of molecular structure.

Non-Born-Oppenheimer electronic and nuclear densities for a Hooke-Calogero three-particle model: Non-uniqueness of density-derived molecular structure

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

Ludena, E. V.; Echevarria, L.; Lopez, X.

2012-02-28

We consider the calculation of non-Born-Oppenheimer, nBO, one-particle densities for both electrons and nuclei. We show that the nBO one-particle densities evaluated in terms of translationally invariant coordinates are independent of the wavefunction describing the motion of center of mass of the whole system. We show that they depend, however, on an arbitrary reference point from which the positions of the vectors labeling the particles are determined. We examine the effect that this arbitrary choice has on the topology of the one-particle density by selecting the Hooke-Calogero model of a three-body system for which expressions for the one-particle densities canmore » be readily obtained in analytic form. We extend this analysis to the one-particle densities obtained from full Coulomb interaction wavefunctions for three-body systems. We conclude, in view of the fact that there is a close link between the choice of the reference point and the topology of one-particle densities that the molecular structure inferred from the topology of these densities is not unique. We analyze the behavior of one-particle densities for the Hooke-Calogero Born-Oppenheimer, BO, wavefunction and show that topological transitions are also present in this case for a particular mass value of the light particles even though in the BO regime the nuclear masses are infinite. In this vein, we argue that the change in topology caused by variation of the mass ratio between light and heavy particles does not constitute a true indication in the nBO regime of the emergence of molecular structure.« less

Experimental charge density analysis of a gallium(I) N-heterocyclic carbene analogue.

PubMed

Overgaard, Jacob; Jones, Cameron; Dange, Deepak; Platts, James A

2011-09-05

The experimental electron density of the only known example of a four-membered Ga(I) N-heterocyclic carbene analogue has been determined by multipole modeling of 90 K X-ray diffraction data and compared to theoretical data. In order to obtain a satisfactory model, it is necessary to modify the radial dependency of the core electrons of Ga using two separate scaling parameters for s,p- and d-electrons. Evidence for significant lone-pair density on Ga is found in the electron density and derived properties despite the partial positive charge of this atom. Static deformation density and molecular electrostatic potential clearly show a directional lone pair on Ga, whereas the Laplacian of the total electron density does not; this feature is, however, present in the Laplacian of the valence-only density. The Ga center also acts as an acceptor in four intramolecular C-H···Ga contacts, whose nature is probed by density properties. Substantial covalent character is apparent in the Ga-N bonds, but no sign of donation from filled N p-orbitals to empty Ga p-orbitals is found, whereas π-delocalization over the organic ligand is evident. This study highlights the utility of experimental charge density analysis as a technique to investigate the unusual bonding and electronic characteristics of low oxidation state/low coordinate p-block complexes.

Molecular structure and vibrational spectra of three substituted 4-thioflavones by density functional theory and ab initio Hartree-Fock calculations

NASA Astrophysics Data System (ADS)

Li, Xiao-Hong; Liu, Xiang-Ru; Zhang, Xian-Zhou

2011-01-01

The vibrational frequencies of three substituted 4-thioflavones in the ground state have been calculated using the Hartree-Fock and density functional method (B3LYP) with 6-31G* and 6-31+G** basis sets. The structural analysis shows that there exists H-bonding in the selected compounds and the hydrogen bond lengths increase with the augment of the conjugate parameters of the substituent group on the benzene ring. A complete vibrational assignment aided by the theoretical harmonic wavenumber analysis was proposed. The theoretical spectrograms for FT-IR spectra of the title compounds have been constructed. In addition, it is noted that the selected compounds show significant activity against Shigella flexniri. Several electronic properties and thermodynamic parameters were also calculated.

Thermal Analysis of Low Layer Density Multilayer Insulation Test Results

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.

2011-01-01

Investigation of the thermal performance of low layer density multilayer insulations is important for designing long-duration space exploration missions involving the storage of cryogenic propellants. Theoretical calculations show an analytical optimal layer density, as widely reported in the literature. However, the appropriate test data by which to evaluate these calculations have been only recently obtained. As part of a recent research project, NASA procured several multilayer insulation test coupons for calorimeter testing. These coupons were configured to allow for the layer density to be varied from 0.5 to 2.6 layer/mm. The coupon testing was completed using the cylindrical Cryostat-l00 apparatus by the Cryogenics Test Laboratory at Kennedy Space Center. The results show the properties of the insulation as a function of layer density for multiple points. Overlaying these new results with data from the literature reveals a minimum layer density; however, the value is higher than predicted. Additionally, the data show that the transition region between high vacuum and no vacuum is dependent on the spacing of the reflective layers. Historically this spacing has not been taken into account as thermal performance was calculated as a function of pressure and temperature only; however the recent testing shows that the data is dependent on the Knudsen number which takes into account pressure, temperature, and layer spacing. These results aid in the understanding of the performance parameters of MLI and help to complete the body of literature on the topic.

Structural and electrochemical analysis of chemically synthesized microcubic architectured lead selenide thin films

NASA Astrophysics Data System (ADS)

Bhat, T. S.; Shinde, A. V.; Devan, R. S.; Teli, A. M.; Ma, Y. R.; Kim, J. H.; Patil, P. S.

2018-01-01

The present work deals with the synthesis of lead selenide (PbSe) thin films by simple and cost-effective chemical bath deposition method with variation in deposition time. The structural, morphological, and electrochemical properties of as-deposited thin films were examined using characterization techniques such as X-ray diffraction spectroscopy (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy. XRD reveals formation of rock salt phase cubic structured PbSe. FE-SEM images show the formation of microcubic structured morphology. The existence of the PbSe is confirmed from the XPS analysis. On the other hand, CV curves show four reaction peaks corresponding to oxidation [PbSe and Pb(OH)2] and reduction (PbO2 and Pb(OH)2) at the surface of PbSe thin films. The PbSe:2 sample deposited for 80 min. shows maximum specific capacitance of 454 ± 5 F g- 1 obtained at 0.25 mA cm- 2 current density. The maximum energy density of 69 Wh kg- 1 was showed by PbSe:2 electrode with a power density of 1077 W kg- 1. Furthermore, electrochemical impedance studies of PbSe:2 thin film show 80 ± 3% cycling stability even after 500 CV cycles. Such results show the importance of microcubic structured PbSe thin film as an anode in supercapacitor devices.

Cytonuclear Epistasis Controls the Density of Symbiont Wolbachia pipientis in Nongonadal Tissues of Mosquito Culex quinquefasciatus.

PubMed

Emerson, Kevin J; Glaser, Robert L

2017-08-07

Wolbachia pipientis , a bacterial symbiont infecting arthropods and nematodes, is vertically transmitted through the female germline and manipulates its host's reproduction to favor infected females. Wolbachia also infects somatic tissues where it can cause nonreproductive phenotypes in its host, including resistance to viral pathogens. Wolbachia -mediated phenotypes are strongly associated with the density of Wolbachia in host tissues. Little is known, however, about how Wolbachia density is regulated in native or heterologous hosts. Here, we measure the broad-sense heritability of Wolbachia density among families in field populations of the mosquito Culex pipiens , and show that densities in ovary and nongonadal tissues of females in the same family are not correlated, suggesting that Wolbachia density is determined by distinct mechanisms in the two tissues. Using introgression analysis between two different strains of the closely related species C. quinquefasciatus , we show that Wolbachia densities in ovary tissues are determined primarily by cytoplasmic genotype, while densities in nongonadal tissues are determined by both cytoplasmic and nuclear genotypes and their epistatic interactions. Quantitative-trait-locus mapping identified two major-effect quantitative-trait loci in the C. quinquefasciatus genome explaining a combined 23% of variance in Wolbachia density, specifically in nongonadal tissues. A better understanding of how Wolbachia density is regulated will provide insights into how Wolbachia density can vary spatiotemporally in insect populations, leading to changes in Wolbachia -mediated phenotypes such as viral pathogen resistance. Copyright © 2017 Emerson, Glaser.

Effect of cell density on adipogenic differentiation of mesenchymal stem cells

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

Lu, Hongxu; Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044; Guo, Likun

2009-04-10

The effect of cell density on the adipogenic differentiation of human bone marrow-derived mesenchymal stem cells (MSCs) was investigated by using a patterning technique to induce the formation of a cell density gradient on a micropatterned surface. The adipogenic differentiation of MSCs at a density gradient from 5 x 10{sup 3} to 3 x 10{sup 4} cells/cm{sup 2} was examined. Lipid vacuoles were observed at all cell densities after 1-3 weeks of culture in adipogenic differentiation medium although the lipid vacuoles were scarce at the low cell density and abundant at the high cell density. Real-time RT-PCR analysis showed thatmore » adipogenesis marker genes encoding peroxisome proliferator-activated receptor {gamma}2 (PPAR{gamma}2), lipoprotein lipase (LPL), and fatty acid binding protein-4 (FABP4) were detected in the MSCs cultured at all cell densities. The results suggest that there was no apparent effect of cell density on the adipogenic differentiation of human MSCs.« less

Experimental micromechanical approach to failure process in CFRP cross-ply laminates

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

Takeda, N.; Ogihara, S.; Kobayashi, A.

The microscopic failure process of three different types of cross-ply laminates, (0/90{sub n}/0) (n = 4, 8, 12), was investigated at R.T. and 80 C. Progressive damage parameters, the transverse crack density and the delamination ratio, were measured. A simple modified shear-lag analysis including the thermal residual strains was conducted to predict the transverse crack density as a function of laminate strain, considering the constraint effect, as well as the strength distribution of the transverse layer. The analysis was also extended to the system containing delamination to predict the delamination length. A prediction was also presented for the transverse crackmore » density including the effect of the delamination growth. The prediction showed good agreement with the experimental results.« less

Population Dynamics of Dactylella oviparasitica and Heterodera schachtii: Toward a Decision Model for Sugar Beet Planting

PubMed Central

Yang, Jiue-in; Benecke, Scott; Jeske, Daniel R.; Rocha, Fernando S.; Smith Becker, Jennifer; Timper, Patricia; Ole Becker, J.

2012-01-01

A series of experiments were performed to examine the population dynamics of the sugarbeet cyst nematode, Heterodera schachtii, and the nematophagus fungus Dactylella oviparasitica. After two nematode generations, the population densities of H. schachtii were measured in relation to various initial infestation densities of both D. oviparasitica and H. schachtii. In general, higher initial population densities of D. oviparasitica were associated with lower final population densities of H. schachtii. Regression models showed that the initial densities of D. oviparasitica were only significant when predicting the final densities of H. schachtii J2 and eggs as well as fungal egg parasitism, while the initial densities of J2 were significant for all final H. schachtii population density measurements. We also showed that the densities of H. schachtii-associated D. oviparasitica fluctuate greatly, with rRNA gene numbers going from zero in most field-soil-collected cysts to an average of 4.24 x 108 in mature females isolated directly from root surfaces. Finally, phylogenetic analysis of rRNA genes suggested that D. oviparasitica belongs to a clade of nematophagous fungi that includes Arkansas Fungus strain L (ARF-L) and that these fungi are widely distributed. We anticipate that these findings will provide foundational data facilitating the development of more effective decision models for sugar beet planting. PMID:23481664

Lianas escape self-thinning: Experimental evidence of positive density dependence in temperate lianas Celastrus orbiculatus and C. scandens

USGS Publications Warehouse

Leicht-Young, S. A.; Latimer, A.M.; Silander, J.A.

2011-01-01

The neighborhood density of plants strongly affects their growth, reproduction, and survival. In most cases, high density increases competition and negatively affects a focal plant in predictable ways, leading to the self-thinning law. There are, however, situations in which high densities of plants facilitate focal plant performance, resulting in positive density dependence. Despite their importance in forest gap dynamics and distinctive growth form, there have been very few studies of the effect of density on lianas or vines. We grew an invasive (Celastrus orbiculatus) and a native (Celastrus scandens) liana species together in three different density treatments, while also manipulating the light and support availability. We found that across treatment conditions, C. orbiculatus always out-performed C. scandens, showing greater relative growth rate in height and diameter, greater biomass and higher survival. Both species responded similarly to the density treatments: with plants in high density not showing a decrease in relative height growth rate compared to medium density. Aboveground biomass for C. scandens was not affected by density, while for C. orbiculatus, the most massive plants were growing in medium density without support. More surprisingly, survival analysis indicated that the two species both had significantly lower mortality rates in the highest density treatment; this trend held true across the other treatments of light and supports. More generally, this study demonstrates that these lianas can escape the consequences of high density and thus the self-thinning law that affects self-supporting plants. This suggests a broader hypothesis about lianas in general: their greater flexibility in allocating growth resources allows them to grow taller and thinner without collapsing and thereby potentially escape shading and mortality even at high densities.

Social identification moderates the effect of crowd density on safety at the Hajj.

PubMed

Alnabulsi, Hani; Drury, John

2014-06-24

Crowd safety is a major concern for those attending and managing mass gatherings, such as the annual Hajj or pilgrimage to Mecca (also called Makkah). One threat to crowd safety at such events is crowd density. However, recent research also suggests that psychological membership of crowds can have positive benefits. We tested the hypothesis that the effect of density on safety might vary depending on whether there is shared social identification in the crowd. We surveyed 1,194 pilgrims at the Holy Mosque, Mecca, during the 2012 Hajj. Analysis of the data showed that the negative effect of crowd density on reported safety was moderated by social identification with the crowd. Whereas low identifiers reported reduced safety with greater crowd density, high identifiers reported increased safety with greater crowd density. Mediation analysis suggested that a reason for these moderation effects was the perception that other crowd members were supportive. Differences in reported safety across national groups (Arab countries and Iran compared with the rest) were also explicable in terms of crowd identification and perceived support. These findings support a social identity account of crowd behavior and offer a novel perspective on crowd safety management.

Social identification moderates the effect of crowd density on safety at the Hajj

PubMed Central

Alnabulsi, Hani; Drury, John

2014-01-01

Crowd safety is a major concern for those attending and managing mass gatherings, such as the annual Hajj or pilgrimage to Mecca (also called Makkah). One threat to crowd safety at such events is crowd density. However, recent research also suggests that psychological membership of crowds can have positive benefits. We tested the hypothesis that the effect of density on safety might vary depending on whether there is shared social identification in the crowd. We surveyed 1,194 pilgrims at the Holy Mosque, Mecca, during the 2012 Hajj. Analysis of the data showed that the negative effect of crowd density on reported safety was moderated by social identification with the crowd. Whereas low identifiers reported reduced safety with greater crowd density, high identifiers reported increased safety with greater crowd density. Mediation analysis suggested that a reason for these moderation effects was the perception that other crowd members were supportive. Differences in reported safety across national groups (Arab countries and Iran compared with the rest) were also explicable in terms of crowd identification and perceived support. These findings support a social identity account of crowd behavior and offer a novel perspective on crowd safety management. PMID:24927593

2-D Density and Directional Analysis of Fault Systems in the Zagros Region (Iran) on a Regional Scale

NASA Astrophysics Data System (ADS)

Hashemi, Seyed Naser; Baizidi, Chavare

2018-04-01

In this paper, 2-D spatial variation of the frequency and length density and frequency-length relation of large-scale faults in the Zagros region (Iran), as a typical fold-and-thrust belt, were examined. Moreover, the directional analysis of these faults as well as the scale dependence of the orientations was studied. For this purpose, a number of about 8000 faults with L ≥ 1.0 km were extracted from the geological maps covering the region, and then, the data sets were analyzed. The overall pattern of the frequency/length distribution of the total faults of the region acceptably fits with a power-law relation with exponent 1.40, with an obvious change in the gradient in L = 12.0 km. In addition, maps showing the spatial variation of fault densities over the region indicate that the maximum values of the frequency and length density of the faults are attributed to the northeastern part of the region and parallel to the suture zone, respectively, and the fault density increases towards the central parts of the belt. Moreover, the directional analysis of the fault trends gives a dominant preferred orientation trend of 300°-330° and the assessment of the scale dependence of the fault directions demonstrates that larger faults show higher degrees of preferred orientations. As a result, it is concluded that the evolutionary path of the faulting process in this region can be explained by increasing the number of faults rather than the growth in the fault lengths and also it seems that the regional-scale faults in this region are generated by a nearly steady-state tectonic stress regime.

Analysis of current density and specific absorption rate in biological tissue surrounding transcutaneous transformer for an artificial heart.

PubMed

Shiba, Kenji; Nukaya, Masayuki; Tsuji, Toshio; Koshiji, Kohji

2008-01-01

This paper reports on the current density and specific absorption rate (SAR) analysis of biological tissue surrounding an air-core transcutaneous transformer for an artificial heart. The electromagnetic field in the biological tissue is analyzed by the transmission line modeling method, and the current density and SAR as a function of frequency, output voltage, output power, and coil dimension are calculated. The biological tissue of the model has three layers including the skin, fat, and muscle. The results of simulation analysis show SARs to be very small at any given transmission conditions, about 2-14 mW/kg, compared to the basic restrictions of the International Commission on nonionizing radiation protection (ICNIRP; 2 W/kg), while the current density divided by the ICNIRP's basic restrictions gets smaller as the frequency rises and the output voltage falls. It is possible to transfer energy below the ICNIRP's basic restrictions when the frequency is over 250 kHz and the output voltage is under 24 V. Also, the parts of the biological tissue that maximized the current density differ by frequencies; in the low frequency is muscle and in the high frequency is skin. The boundary is in the vicinity of the frequency 600-1000 kHz.

Alcohol outlet density and violence: a geospatial analysis.

PubMed

Zhu, L; Gorman, D M; Horel, S

2004-01-01

To examine the relationship between alcohol outlet density and violent crime controlling for neighbourhood sociostructural characteristics and the effects of spatially autocorrelated error. The sample for this ecologic study comprised 188 census tracts from the City of Austin, Texas and 263 tracts from the City of San Antonio, Texas. Data pertaining to neighbourhood social structure, alcohol density and violent crime were collected from archival sources, and analysed using bivariate, multivariate and geospatial analyses. Using ordinary least squares analysis, the neighbourhood sociostructural covariates explained close to 59% of the variability in violent crime rates in Austin and close to 39% in San Antonio. Adding alcohol outlet density in the target and adjacent census tracts improved the explanatory power of both models. Alcohol outlet density in the target census tract remained a significant predictor of violent crime rates in both cities when the effects of autocorrelated error were controlled for. In Austin, the effects of alcohol outlet density in the adjacent census tracts also remained significant. The final model explains 71% of the variance in violent crime in Austin and 56% in San Antonio. The findings show a clear association between alcohol outlet density and violence, and suggest that the issues of alcohol availability and access are fundamental to the prevention of alcohol-related problems within communities.

[Dietary patterns in college freshmen and its relation to bone mineral density].

PubMed

Wang, Sufang; Mu, Min; Zhao, Yan; Wang, Xiaoqin; Shu, Long; Li, Qingyan; Li, Yingchun

2012-07-01

In order to investigate the bone density of freshmen, and to analyze the association between dietary pattern and bone mineral density (BMD). A questionnaire survey on the situation of dietary pattern was conducted in 1414 freshmen. Effective dietary survey questionnaires and bone mineral density measurements were completed for 1319 participants. Bone mass was assessed by using an Ultrasound Bone Densitometer on the right calcaneus (CM-200, Furuno Electric Corporation, Japan), and the speed of sound (SOS, m/s) was used as an indicator for bone density. Factor analysis with varimax rotation was used to identify the dietary patterns. After adjusting for confounders, covariance with Bonferroni's was used to further examine the associations between dietary patterns and bone mineral density (BMD). (1) Four major dietary patterns were noticed. Western food pattern (high consumption in hamburger, fried food, nuts, biscuit, chocolate, cola, coffee, sugars). Animal protein pattern (high consumption in pork, mutton, beef, poultry meat, animal liver). Calcium pattern (high consumption in fresh fruits, eggs, fish and shrimps, kelp laver and sea fish, milk and dairy products, beans and bean products). Traditional Chinese pattern (high consumption in rice and grain, fresh fruits, fresh vegetables, pork). (2) No association was observed between the western food pattern and bone mineral density. High animal protein pattern showed lower SOS value compared with low animal protein pattern. High calcium pattern showed higher SOS value compared with low calcium pattern. High traditional Chinese pattern showed higher SOS value compared with the low traditional Chinese pattern. Dietary patterns are closely related with bone mineral density (BMD) of freshmen.

Weighing the galactic disc using the Jeans equation: lessons from simulations

NASA Astrophysics Data System (ADS)

Candlish, G. N.; Smith, R.; Moni Bidin, C.; Gibson, B. K.

2016-03-01

Using three-dimensional stellar kinematic data from simulated galaxies, we examine the efficacy of a Jeans equation analysis in reconstructing the total disk surface density, including the dark matter, at the `Solar' radius. Our simulation data set includes galaxies formed in a cosmological context using state-of-the-art high-resolution cosmological zoom simulations, and other idealized models. The cosmologically formed galaxies have been demonstrated to lie on many of the observed scaling relations for late-type spirals, and thus offer an interesting surrogate for real galaxies with the obvious advantage that all the kinematical data are known perfectly. We show that the vertical velocity dispersion is typically the dominant kinematic quantity in the analysis, and that the traditional method of using only the vertical force is reasonably effective at low heights above the disk plane. At higher heights the inclusion of the radial force becomes increasingly important. We also show that the method is sensitive to uncertainties in the measured disk parameters, particularly the scalelengths of the assumed double exponential density distribution, and the scalelength of the radial velocity dispersion. In addition, we show that disk structure and low number statistics can lead to significant errors in the calculated surface densities. Finally, we examine the implications of our results for previous studies of this sort, suggesting that more accurate measurements of the scalelengths may help reconcile conflicting estimates of the local dark matter density in the literature.

Composition and structure of the Chironomidae (Insecta: Diptera) community associated with bryophytes in a first-order stream in the Atlantic forest, Brazil.

PubMed

Rosa, B F J V; Dias-Silva, M V D; Alves, R G

2013-02-01

This study describes the structure of the Chironomidae community associated with bryophytes in a first-order stream located in a biological reserve of the Atlantic Forest, during two seasons. Samples of bryophytes adhered to rocks along a 100-m stretch of the stream were removed with a metal blade, and 200-mL pots were filled with the samples. The numerical density (individuals per gram of dry weight), Shannon's diversity index, Pielou's evenness index, the dominance index (DI), and estimated richness were calculated for each collection period (dry and rainy). Linear regression analysis was employed to test the existence of a correlation between rainfall and the individual's density and richness. The high numerical density and richness of Chironomidae taxa observed are probably related to the peculiar conditions of the bryophyte habitat. The retention of larvae during periods of higher rainfall contributed to the high density and richness of Chironomidae larvae. The rarefaction analysis showed higher richness in the rainy season related to the greater retention of food particles. The data from this study show that bryophytes provide stable habitats for the colonization by and refuge of Chironomidae larvae, mainly under conductions of faster water flow and higher precipitation.

Age related changes in the bone tissue under conditions of hypokinesia

NASA Technical Reports Server (NTRS)

Podrushnyak, E. P.; Suslov, E. I.

1980-01-01

Microroentgenography of nine young people, aged 24-29, before and after hypokinesia (16-37 days strict bed rest), showed that the heel bone density of those with initially high bone density generally decreased and that of those with initially low bone density generally increased. X-ray structural analysis of the femurs of 25 corpses of accidentally killed healthy people, aged 18-70, data are presented and discussed, with the conclusion that the bone hydroxyapatite crystal structure stabilizes by ages 20 to 25, is stable from ages 25 to 60 and decreases in density after age 60. It is concluded that bone tissue structure changes, both with age, and in a comparatively short time in hypokinesia.

Quantum oscillations in a biaxial pair density wave state.

PubMed

Norman, M R; Davis, J C Séamus

2018-05-22

There has been growing speculation that a pair density wave state is a key component of the phenomenology of the pseudogap phase in the cuprates. Recently, direct evidence for such a state has emerged from an analysis of scanning tunneling microscopy data in halos around the vortex cores. By extrapolation, these vortex halos would then overlap at a magnetic-field scale where quantum oscillations have been observed. Here, we show that a biaxial pair density wave state gives a unique description of the quantum oscillation data, bolstering the case that the pseudogap phase in the cuprates may be a pair density wave state. Copyright © 2018 the Author(s). Published by PNAS.

Proton elastic scattering from tin isotopes at 295 MeV and systematic change of neutron density distributions

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

Terashima, S.; Sakaguchi, H.; Takeda, H.

Cross sections and analyzing powers for proton elastic scattering from {sup 116,118,120,122,124}Sn at 295 MeV have been measured for a momentum transfer of up to about 3.5 fm{sup -1} to deduce systematic changes of the neutron density distribution. We tuned the relativistic Love-Franey interaction to explain the proton elastic scattering of a nucleus whose density distribution is well known. Then, we applied this interaction to deduce the neutron density distributions of tin isotopes. The result of our analysis shows the clear systematic behavior of a gradual increase in the neutron skin thickness of tin isotopes with mass number.

Application of Semiparametric Spline Regression Model in Analyzing Factors that In uence Population Density in Central Java

NASA Astrophysics Data System (ADS)

Sumantari, Y. D.; Slamet, I.; Sugiyanto

2017-06-01

Semiparametric regression is a statistical analysis method that consists of parametric and nonparametric regression. There are various approach techniques in nonparametric regression. One of the approach techniques is spline. Central Java is one of the most densely populated province in Indonesia. Population density in this province can be modeled by semiparametric regression because it consists of parametric and nonparametric component. Therefore, the purpose of this paper is to determine the factors that in uence population density in Central Java using the semiparametric spline regression model. The result shows that the factors which in uence population density in Central Java is Family Planning (FP) active participants and district minimum wage.

One-Step Pyrolytic Synthesis of Multiwalled Carbon Nanotubes: The Role of Resupply of Carbon Species on the Quality Control.

PubMed

Rajavel, Krishnamoorthy; Saravanan, Padmanapan; Kumar, Ramasamy Thangavelu Rajendra

2018-05-01

An investigation on varying experimental parameters such as solution quantity (2.5, 5 and 7.5 mL) and reaction time (15, 30, 45 and 60 min) was carried out for the production of high-quality multiwalled carbon nanotubes (MWCNTs) in one step pyrolysis. Structural analysis revealed the uniform diameter distribution and the length of nanotubes in the range of 60-80 nm and 0.4-2 μm, respectively. Raman and X-ray diffraction analysis showed a remarkable reduction in defect density with increase in graphitization degree, upon increasing the solution volume and reaction time. MWCNTs prepared at higher solution quantity (7.5 mL) with higher reaction time (60 min) showed higher crystallinity (70% graphitization) and lower defect density (ID/IG: 0.56). The attainment in equilibrium of evaporation cum precipitation in formation of high quality nanotubes structure is evaluated. An effective resupplying of condensed precursors by re-evaporation leads for the achievement of low defect density nanotubes with higher product yield is achieved.

Numerical analysis and optimization of Cu2O/TiO2, CuO/TiO2, heterojunction solar cells using SCAPS

NASA Astrophysics Data System (ADS)

Sawicka-Chudy, Paulina; Sibiński, Maciej; Wisz, Grzegorz; Rybak-Wilusz, Elżbieta; Cholewa, Marian

2018-05-01

In the presented work, the Cu2O/TiO2 and CuO/TiO2 heterojunction solar cells have been analyzed by the help of Solar Cell Capacitance Simulator (SCAPS). The effects of various layer parameters like thickness and defect density on the cell performance have been studied in details. Numerical analysis showed how the absorber (CuO, Cu2O) and buffer (TiO2) layers thickness influence the short-circuit current density (Jsc) and efficiency (η) of solar cells. Optimized solar cell structures of Cu2O/TiO2 and CuO/TiO2 showed a potential efficiency of ∼9 and ∼23%, respectively, under the AM1.5G spectrum. Additionally, external quantum efficiency (EQE) curves of the CuO/TiO2 and Cu2O/TiO2 solar cells for various layers thickness of TiO2 were calculated and the optical band gap (Eg) for CuO and Cu2O was obtained. Finally, we examined the effects of defect density on the photovoltaic parameters.

The most intense electric currents in turbulent high speed solar wind

NASA Astrophysics Data System (ADS)

Podesta, J. J.

2017-12-01

Theory and simulations suggest that dissipation of turbulent energy in collisionless astrophysical plasmas occurs most rapidly in spatial regions where the current density is most intense. To advance understanding of plasma heating by turbulent dissipation in the solar corona and solar wind, it is of interest to characterize the properties of plasma regions where the current density takes exceptionally large values and to identify the operative dissipation processes. In the solar wind, the curl of the magnetic field cannot be measured using data from a single spacecraft, however, a suitable proxy for this quantity can be constructed from the spatial derivative of the magnetic field along the flow direction of the plasma. This new approach is used to study the properties of the most intense current carrying structures in a high speed solar wind stream near 1 AU. In this study, based on 11 Hz magnetometer data from the WIND spacecraft, the spatial resolution of the proxy technique is approximately equal to the proton inertial length. Intense current sheets or current carrying structures were identified as events where the magnitude of the current density exceeds μ+5σ, where μ and σ are the mean and standard deviation of the magnitude of the current density (or its proxy), respectively. Statistical studies show (1) the average size of these 5σ events is close to the smallest resolvable scale in the data set, the proton inertial length; (2) the linear distance between neighboring events follows a power law distribution; and (3) the average peak current density of 5σ events is around 1 pA/cm2. The analysis techniques used in these studies have been validated using simulated spacecraft data from three dimensional hybrid simulations which show that results based on the analysis of the proxy are qualitatively and quantitatively similar to results based on the analysis of the true current density.

Density-based Energy Decomposition Analysis for Intermolecular Interactions with Variationally Determined Intermediate State Energies

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

Wu, Q.; Ayers, P.W.; Zhang, Y.

2009-10-28

The first purely density-based energy decomposition analysis (EDA) for intermolecular binding is developed within the density functional theory. The most important feature of this scheme is to variationally determine the frozen density energy, based on a constrained search formalism and implemented with the Wu-Yang algorithm [Q. Wu and W. Yang, J. Chem. Phys. 118, 2498 (2003) ]. This variational process dispenses with the Heitler-London antisymmetrization of wave functions used in most previous methods and calculates the electrostatic and Pauli repulsion energies together without any distortion of the frozen density, an important fact that enables a clean separation of these twomore » terms from the relaxation (i.e., polarization and charge transfer) terms. The new EDA also employs the constrained density functional theory approach [Q. Wu and T. Van Voorhis, Phys. Rev. A 72, 24502 (2005)] to separate out charge transfer effects. Because the charge transfer energy is based on the density flow in real space, it has a small basis set dependence. Applications of this decomposition to hydrogen bonding in the water dimer and the formamide dimer show that the frozen density energy dominates the binding in these systems, consistent with the noncovalent nature of the interactions. A more detailed examination reveals how the interplay of electrostatics and the Pauli repulsion determines the distance and angular dependence of these hydrogen bonds.« less

Reducing wall plasma expansion with gold foam irradiated by laser

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

Zhang, Lu; Ding, Yongkun, E-mail: ding-yk@vip.sina.com; Jiang, Shaoen, E-mail: jiangshn@vip.sina.com

The experimental study on the expanding plasma movement of low-density gold foam (∼1% solid density) irradiated by a high power laser is reported in this paper. Experiments were conducted using the SG-III prototype laser. Compared to solid gold with 19.3 g/cc density, the velocities of X-ray emission fronts moving off the wall are much smaller for gold foam with 0.3 g/cc density. Theoretical analysis and MULTI 1D simulation results also show less plasma blow-off, and that the density contour movement velocities of gold foam are smaller than those of solid gold, agreeing with experimental results. These results indicate that foam walls havemore » advantages in symmetry control and lowering plasma fill when used in ignition hohlraum.« less

Invasive alien species water hyacinth Eichhornia crassipes as abode for macroinvertebrates in hypertrophic Ramsar Site, Lake Xochimilco, Mexico.

PubMed

Rocha-Ramirez, A; Robles-Valderrama, E; Ramirez-Flores, E

2014-11-01

This paper presents information on the density, diversity and functional feeding groups of macroinvertebrate assemblages associated with water hyacinth in Antiguo Canal Cuemanco, part of Lake Xochimilco in Mexico City. Rare (low frequency and density) and dominant (high frequency and density) taxa prevailed in the assemblages, with the most predominant being Hyalella azteca, Chironomus plumosus and Ischnura denticollis. Nonmetric Multidimensional Scaling confirmed two climatic seasons: warm-rainy and cold-dry; the former with the highest diversity and density of taxa. Canonical Correspondence Analysis showed that conductivity, nitrates and turbidity explained the density variations of taxa. Antiguo Canal Cuemanco waters are spatially homogeneous with the characteristics of hypertrophic shallow lakes, inhabited by scrapers and gathering-collectors. The species found were tolerant to organic pollution.

[Spatial analysis of road traffic accidents with fatalities in Spain, 2008-2011].

PubMed

Gómez-Barroso, Diana; López-Cuadrado, Teresa; Llácer, Alicia; Palmera Suárez, Rocío; Fernández-Cuenca, Rafael

2015-09-01

To estimate the areas of greatest density of road traffic accidents with fatalities at 24 hours per km(2)/year in Spain from 2008 to 2011, using a geographic information system. Accidents were geocodified using the road and kilometer points where they occurred. The average nearest neighbor was calculated to detect possible clusters and to obtain the bandwidth for kernel density estimation. A total of 4775 accidents were analyzed, of which 73.3% occurred on conventional roads. The estimated average distance between accidents was 1,242 meters, and the average expected distance was 10,738 meters. The nearest neighbor index was 0.11, indicating that there were aggregations of accidents in space. A map showing the kernel density was obtained with a resolution of 1 km(2), which identified the areas of highest density. This methodology allowed a better approximation to locating accident risks by taking into account kilometer points. The map shows areas where there was a greater density of accidents. This could be an advantage in decision-making by the relevant authorities. Copyright © 2014 SESPAS. Published by Elsevier Espana. All rights reserved.

A spatial analysis of health-related resources in three diverse metropolitan areas

PubMed Central

Smiley, Melissa J.; Diez Roux, Ana V.; Brines, Shannon J.; Brown, Daniel G.; Evenson, Kelly R.; Rodriguez, Daniel A.

2010-01-01

Few studies have investigated the spatial clustering of multiple health-related resources. We constructed 0.5-mile kernel densities of resources for census areas in New York City, NY (n=819 block groups), Baltimore, MD (n=737), and Winston-Salem, NC (n=169). Three of the four resource densities (supermarkets/produce stores, retail areas, and recreational facilities) tended to be correlated with each other, whereas park density was less consistently and sometimes negatively correlated with the others. Blacks were more likely to live in block groups with multiple low resource densities. Spatial regression models showed that block groups with higher proportions of black residents tended to have lower supermarket/produce, retail, and recreational facility densities, although these associations did not always achieve statistical significance. A measure that combined local and neighboring block group racial composition was often a stronger predictor of resources than the local measure alone. Overall, our results from three diverse U.S. cities show that health-related resources are not randomly distributed across space and that disadvantage in multiple domains often clusters with residential racial patterning. PMID:20478737

A Si IV/O IV Electron Density Diagnostic for the Analysis of IRIS Solar Spectra

NASA Astrophysics Data System (ADS)

Young, P. R.; Keenan, F. P.; Milligan, R. O.; Peter, H.

2018-04-01

Solar spectra of ultraviolet bursts and flare ribbons from the Interface Region Imaging Spectrograph (IRIS) have suggested high electron densities of > {10}12 cm‑3 at transition region temperatures of 0.1 MK, based on large intensity ratios of Si IV λ1402.77 to O IV λ1401.16. In this work, a rare observation of the weak O IV λ1343.51 line is reported from an X-class flare that peaked at 21:41 UT on 2014 October 24. This line is used to develop a theoretical prediction of the Si IV λ1402.77 to O IV λ1401.16 ratio as a function of density that is recommended to be used in the high-density regime. The method makes use of new pressure-dependent ionization fractions that take account of the suppression of dielectronic recombination at high densities. It is applied to two sequences of flare kernel observations from the October 24 flare. The first shows densities that vary between 3× {10}12 and 3× {10}13 cm‑3 over a seven-minute period, while the second location shows stable density values of around 2× {10}12 cm‑3 over a three-minute period.

Counting Cats: Spatially Explicit Population Estimates of Cheetah (Acinonyx jubatus) Using Unstructured Sampling Data

PubMed Central

Broekhuis, Femke; Gopalaswamy, Arjun M.

2016-01-01

Many ecological theories and species conservation programmes rely on accurate estimates of population density. Accurate density estimation, especially for species facing rapid declines, requires the application of rigorous field and analytical methods. However, obtaining accurate density estimates of carnivores can be challenging as carnivores naturally exist at relatively low densities and are often elusive and wide-ranging. In this study, we employ an unstructured spatial sampling field design along with a Bayesian sex-specific spatially explicit capture-recapture (SECR) analysis, to provide the first rigorous population density estimates of cheetahs (Acinonyx jubatus) in the Maasai Mara, Kenya. We estimate adult cheetah density to be between 1.28 ± 0.315 and 1.34 ± 0.337 individuals/100km2 across four candidate models specified in our analysis. Our spatially explicit approach revealed ‘hotspots’ of cheetah density, highlighting that cheetah are distributed heterogeneously across the landscape. The SECR models incorporated a movement range parameter which indicated that male cheetah moved four times as much as females, possibly because female movement was restricted by their reproductive status and/or the spatial distribution of prey. We show that SECR can be used for spatially unstructured data to successfully characterise the spatial distribution of a low density species and also estimate population density when sample size is small. Our sampling and modelling framework will help determine spatial and temporal variation in cheetah densities, providing a foundation for their conservation and management. Based on our results we encourage other researchers to adopt a similar approach in estimating densities of individually recognisable species. PMID:27135614

Counting Cats: Spatially Explicit Population Estimates of Cheetah (Acinonyx jubatus) Using Unstructured Sampling Data.

PubMed

Broekhuis, Femke; Gopalaswamy, Arjun M

2016-01-01

Many ecological theories and species conservation programmes rely on accurate estimates of population density. Accurate density estimation, especially for species facing rapid declines, requires the application of rigorous field and analytical methods. However, obtaining accurate density estimates of carnivores can be challenging as carnivores naturally exist at relatively low densities and are often elusive and wide-ranging. In this study, we employ an unstructured spatial sampling field design along with a Bayesian sex-specific spatially explicit capture-recapture (SECR) analysis, to provide the first rigorous population density estimates of cheetahs (Acinonyx jubatus) in the Maasai Mara, Kenya. We estimate adult cheetah density to be between 1.28 ± 0.315 and 1.34 ± 0.337 individuals/100km2 across four candidate models specified in our analysis. Our spatially explicit approach revealed 'hotspots' of cheetah density, highlighting that cheetah are distributed heterogeneously across the landscape. The SECR models incorporated a movement range parameter which indicated that male cheetah moved four times as much as females, possibly because female movement was restricted by their reproductive status and/or the spatial distribution of prey. We show that SECR can be used for spatially unstructured data to successfully characterise the spatial distribution of a low density species and also estimate population density when sample size is small. Our sampling and modelling framework will help determine spatial and temporal variation in cheetah densities, providing a foundation for their conservation and management. Based on our results we encourage other researchers to adopt a similar approach in estimating densities of individually recognisable species.

UV TO FAR-IR CATALOG OF A GALAXY SAMPLE IN NEARBY CLUSTERS: SPECTRAL ENERGY DISTRIBUTIONS AND ENVIRONMENTAL TRENDS

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

Hernandez-Fernandez, Jonathan D.; Iglesias-Paramo, J.; Vilchez, J. M., E-mail: jonatan@iaa.es

2012-03-01

In this paper, we present a sample of cluster galaxies devoted to study the environmental influence on the star formation activity. This sample of galaxies inhabits in clusters showing a rich variety in their characteristics and have been observed by the SDSS-DR6 down to M{sub B} {approx} -18, and by the Galaxy Evolution Explorer AIS throughout sky regions corresponding to several megaparsecs. We assign the broadband and emission-line fluxes from ultraviolet to far-infrared to each galaxy performing an accurate spectral energy distribution for spectral fitting analysis. The clusters follow the general X-ray luminosity versus velocity dispersion trend of L{sub X}more » {proportional_to} {sigma}{sup 4.4}{sub c}. The analysis of the distributions of galaxy density counting up to the 5th nearest neighbor {Sigma}{sub 5} shows: (1) the virial regions and the cluster outskirts share a common range in the high density part of the distribution. This can be attributed to the presence of massive galaxy structures in the surroundings of virial regions. (2) The virial regions of massive clusters ({sigma}{sub c} > 550 km s{sup -1}) present a {Sigma}{sub 5} distribution statistically distinguishable ({approx}96%) from the corresponding distribution of low-mass clusters ({sigma}{sub c} < 550 km s{sup -1}). Both massive and low-mass clusters follow a similar density-radius trend, but the low-mass clusters avoid the high density extreme. We illustrate, with ABELL 1185, the environmental trends of galaxy populations. Maps of sky projected galaxy density show how low-luminosity star-forming galaxies appear distributed along more spread structures than their giant counterparts, whereas low-luminosity passive galaxies avoid the low-density environment. Giant passive and star-forming galaxies share rather similar sky regions with passive galaxies exhibiting more concentrated distributions.« less

Low temperature London penetration depth and superfluid density in Fe-based superconductors

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

Kim, Hyunsoo

2013-01-01

The superconducting gap symmetry of the Fe-based superconductors was studied by measurements and analysis of London penetration depth and super uid density. Tunnel diode resonator technique for these measurements was implemented in a dilution refrigerator allowing for the temperatures down to 50 mK. For the analysis of the super uid density, we used both experimental studies of Al-coated samples and original thermodynamic approach based on Rutgers relation. In three systems studied, we found that the superconducting gap at the optimal doping is best described in multi-gap full gap scenario. By performing experiments on samples with arti cially introduced disorder withmore » heavy ion irradiation, we show that evolution of the superconducting transition temperature and of the super uid density are consistent with full-gap sign changing s superconducting state. The superconducting gap develops strong modulation both in the under-doped and the over-doped regimes. In the terminal hole-doped KFe{sub 2}As{sub 2}, both temperature dependence of the super uid density and its evolution with increase of the scattering rate are consistent with symmetry imposed vertical line nodes in the superconducting gap. By comparative studies of hole-doped (Ba,K)Fe{sub 2}As{sub 2} and electron-doped Ca10-3-8, we show that the superconducting gap modulation in the under-doped regime is intrinsic and is not induced by the coexisting static magnetic order.« less

Patterns of shading tolerance determined from experimental ...

EPA Pesticide Factsheets

An extensive review of the experimental literature on seagrass shading evaluated the relationship between experimental light reductions, duration of experiment and seagrass response metrics to determine whether there were consistent statistical patterns. There were highly significant linear relationships of both percent biomass and percent shoot density reduction versus percent light reduction (versus controls), although unexplained variation in the data were high. Duration of exposure affected extent of response for both metrics, but was more clearly a factor in biomass response. Both biomass and shoot density showed linear responses to duration of light reduction for treatments 60%. Unexplained variation was again high, and greater for shoot density than biomass. With few exceptions, regressions of both biomass and shoot density on light reduction for individual species and for genera were statistically significant, but also tended to show high degrees of variability in data. Multivariate regressions that included both percent light reduction and duration of reduction as dependent variables increased the percentage of variation explained in almost every case. Analysis of response data by seagrass life history category (Colonizing, Opportunistic, Persistent) did not yield clearly separate response relationships in most cases. Biomass tended to show somewhat less variation in response to light reduction than shoot density, and of the two, may be the prefe

Universality of quantum information in chaotic CFTs

NASA Astrophysics Data System (ADS)

Lashkari, Nima; Dymarsky, Anatoly; Liu, Hong

2018-03-01

We study the Eigenstate Thermalization Hypothesis (ETH) in chaotic conformal field theories (CFTs) of arbitrary dimensions. Assuming local ETH, we compute the reduced density matrix of a ball-shaped subsystem of finite size in the infinite volume limit when the full system is an energy eigenstate. This reduced density matrix is close in trace distance to a density matrix, to which we refer as the ETH density matrix, that is independent of all the details of an eigenstate except its energy and charges under global symmetries. In two dimensions, the ETH density matrix is universal for all theories with the same value of central charge. We argue that the ETH density matrix is close in trace distance to the reduced density matrix of the (micro)canonical ensemble. We support the argument in higher dimensions by comparing the Von Neumann entropy of the ETH density matrix with the entropy of a black hole in holographic systems in the low temperature limit. Finally, we generalize our analysis to the coherent states with energy density that varies slowly in space, and show that locally such states are well described by the ETH density matrix.

The spectroscopic (FTIR, FT-Raman and UV-Vis spectra), DFT and normal coordinate computations of m-nitromethylbenzoate

NASA Astrophysics Data System (ADS)

Gnanasambandan, T.; Gunasekaran, S.; Seshadri, S.

2013-08-01

A combined experimental and theoretical study on molecular structure, vibrational spectra, NBO and UV-spectral analysis of m-nitromethylbenzoate (MNMB) has been reported in the present work. The FT-IR solid phase (4000-400 cm-1) and FT-Raman spectra (3500-100 cm-1) of MNMB was recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of MNMB in the ground-state have been calculated by using the density functional method B3LYP with 6-31G (d,p) and 6-31+G(d,p) basis sets. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). Stability of the molecule arising from hyperconjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ∗ antibonding orbitals and E(2) energies confirms the occurrence of ICT (Intra-molecular Charge Transfer) within the molecule. The UV spectrum was measured in ethyl acetate solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) result complements the experimental findings. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the calculation results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra.

LINER galaxy properties and the local environment

NASA Astrophysics Data System (ADS)

Coldwell, Georgina V.; Alonso, Sol; Duplancic, Fernanda; Mesa, Valeria

2018-05-01

We analyse the properties of a sample of 5560 low-ionization nuclear emission-line region (LINER) galaxies selected from SDSS-DR12 at low red shift, for a complete range of local density environments. The host LINER galaxies were studied and compared with a well-defined control sample of 5553 non-LINER galaxies matched in red shift, luminosity, morphology and local density. By studying the distributions of galaxy colours and the stellar age population, we find that LINERs are redder and older than the control sample over a wide range of densities. In addition, LINERs are older than the control sample, at a given galaxy colour, indicating that some external process could have accelerated the evolution of the stellar population. The analysis of the host properties shows that the control sample exhibits a strong relation between colours, ages and the local density, while more than 90 per cent of the LINERs are redder and older than the mean values, independently of the neighbourhood density. Furthermore, a detailed study in three local density ranges shows that, while control sample galaxies are redder and older as a function of stellar mass and density, LINER galaxies mismatch the known morphology-density relation of galaxies without low-ionization features. The results support the contribution of hot and old stars to the low-ionization emission although the contribution of nuclear activity is not discarded.

Electron temperatures within magnetic clouds between 2 and 4 AU: Voyager 2 observations

NASA Astrophysics Data System (ADS)

Sittler, E. C.; Burlaga, L. F.

1998-08-01

We have performed an analysis of Voyager 2 plasma electron observations within magnetic clouds between 2 and 4 AU identified by Burlaga and Behannon [1982]. The analysis has been confined to three of the magnetic clouds identified by Burlaga and Behannon that had high-quality data. The general properties of the plasma electrons within a magnetic cloud are that (1) the moment electron temperature anticorrelates with the electron density within the cloud, (2) the ratio Te/Tp tends to be >1, and (3) on average, Te/Tp~7.0. All three results are consistent with previous electron observations within magnetic clouds. Detailed analyses of the core and halo populations within the magnetic clouds show no evidence of either an anticorrelation between the core temperature TC and the electron density Ne or an anticorrelation between the halo temperature TH and the electron density. Within the magnetic clouds the halo component can contribute more than 50% of the electron pressure. The anticorrelation of Te relative to Ne can be traced to the density of the halo component relative to the density of the core component. The core electrons dominate the electron density. When the density goes up, the halo electrons contribute less to the electron pressure, so we get a lower Te. When the electron density goes down, the halo electrons contribute more to the electron pressure, and Te goes up. We find a relation between the electron pressure and density of the form Pe=αNeγ with γ~0.5.

Measurement of hydroxyapatite density and Knoop hardness in sound human enamel and a correlational analysis between them.

PubMed

He, Bing; Huang, Shengbin; Jing, Junjun; Hao, Yuqing

2010-02-01

The aim of this study was to measure the hydroxyapatite (HAP) density and Knoop hardness (KHN) of enamel slabs and to analyse the relationship between them. Twenty enamel slabs (10 lingual sides and 10 buccal sides) were prepared and scanned with micro-CT. Tomographic images of each slab from dental cusp to dentinoenamel junction (DEJ) were reconstructed. On these three-dimensional (3D) images, regions of interest (ROIs) were defined at an interval of 50 microm, and the HAP density for each ROI was calculated. Then the polished surfaces were indented from cusp to DEJ at intervals of 50 microm with a Knoop indenter. Finally, the data were analysed with one-way ANOVA, Student's t-test, and linear regression analysis. The HAP density and KHN decreased from the dental cusp to DEJ. Both HAP density and KHN in the outer-layer enamel were significantly higher than those in the middle- or inner-layer enamel (P<0.05). The HAP density showed no significant difference between the buccal and lingual sides for enamel in the outer, middle and inner layers, respectively (P>0.05). The KHN in the outer-layer enamel of the lingual sides was significantly lower than that of the buccal sides (P<0.05); there was no significant difference between the lingual and buccal sides in the middle or inner layer. Linear regression analysis revealed a linear relationship between the mean KHN and the mean HAP density (r=0.87). Both HAP density and KHN decrease simultaneously from dental cusp to DEJ, and the two properties are highly correlated. Copyright 2009 Elsevier Ltd. All rights reserved.

Follicle-stimulating hormone and bioavailable estradiol are less important than weight and race in determining bone density in younger postmenopausal women

PubMed Central

Preisser, J. S.; Hammett-Stabler, C. A.; Renner, J. B.; Rubin, J.

2011-01-01

Summary The association between follicle-stimulating hormone (FSH) and bone density was tested in 111 postmenopausal women aged 50–64 years. In the multivariable analysis, weight and race were important determinants of bone mineral density. FSH, bioavailable estradiol, and other hormonal variables did not show statistically significant associations with bone density at any site. Introduction FSH has been associated with bone density loss in animal models and longitudinal studies of women. Most of these analyses have not considered the effect of weight or race. Methods We tested the association between FSH and bone density in younger postmenopausal women, adjusting for patient-related factors. In 111 postmenopausal women aged 50–64 years, areal bone mineral density (BMD) was measured at the lumbar spine, femoral neck, total hip, and distal radius using dual-energy X-ray absorptiometry, and volumetric BMD was measured at the distal radius using peripheral quantitative computed tomography (pQCT). Height, weight, osteoporosis risk factors, and serum hormonal factors were assessed. Results FSH inversely correlated with weight, bioavailable estradiol, areal BMD at the lumbar spine and hip, and volumetric BMD at the ultradistal radius. In the multivariable analysis, no hormonal variable showed a statistically significant association with areal BMD at any site. Weight was independently associated with BMD at all central sites (p<0.001), but not with BMD or pQCT measures at the distal radius. Race was independently associated with areal BMD at all sites (p≤0.008) and with cortical area at the 33% distal radius (p=0.004). Conclusions Correlations between FSH and bioavailable estradiol and BMD did not persist after adjustment for weight and race in younger postmenopausal women. Weight and race were more important determinants of bone density and should be included in analyses of hormonal influences on bone. PMID:21125395

Optical Coherence Tomography Angiography in Optic Disc Swelling.

PubMed

Fard, Masoud Aghsaei; Jalili, Jalil; Sahraiyan, Alireza; Khojasteh, Hassan; Hejazi, Marjane; Ritch, Robert; Subramanian, Prem S

2018-05-04

To compare optical coherence tomography angiography (OCT-A) of peripapillary total vasculature and capillaries in patients with optic disc swelling. Cross-sectional study. Twenty nine eyes with acute nonarteritic anterior ischemic optic neuropathy (NAION), 44 eyes with papilledema, 8 eyes with acute optic neuritis, and 48 eyes of normal subjects were imaged using OCT-A. Peripapillary total vasculature information was recorded using a commercial vessel density map. Customized image analysis with major vessel removal was also used to measure whole-image capillary density and peripapillary capillary density (PCD). Mixed models showed that the peripapillary total vasculature density values were significantly lower in NAION eyes, followed by papilledema eyes and control eyes, using commercial software (P < .0001 for all comparisons). The customized software also showed significantly lower PCD of NAION eyes compared with papilledema eyes (all P < .001), but did not show significant differences between papilledema and control subjects. Our software showed significantly lower whole image and PCD in eyes with optic neuritis than papilledema. There was no significant difference between NAION and optic neuritis using our software. The area under the receiver operating curves for discriminating NAION from papilledema eyes and optic neuritis from papilledema eyes was highest for whole-image capillary density (0.94 and 0.80, respectively) with our software, followed by peripapillary total vasculature (0.9 and 0.74, respectively ) with commercial software. OCT-A is helpful to distinguish NAION and papillitis from papilledema. Whole-image capillary density had the greatest diagnostic accuracy for differentiating disc swelling. Copyright © 2018 Elsevier Inc. All rights reserved.

Schlieren Technique Applied to Magnetohydrodynamic Generator Plasma Torch

NASA Astrophysics Data System (ADS)

Chopra, Nirbhav; Pearcy, Jacob; Jaworski, Michael

2017-10-01

Magnetohydrodynamic (MHD) generators are a promising augmentation to current hydrocarbon based combustion schemes for creating electrical power. In recent years, interest in MHD generators has been revitalized due to advances in a number of technologies such as superconducting magnets, solid-state power electronics and materials science as well as changing economics associated with carbon capture, utilization, and sequestration. We use a multi-wavelength schlieren imaging system to evaluate electron density independently of gas density in a plasma torch under conditions relevant to MHD generators. The sensitivity and resolution of the optical system are evaluated alongside the development of an automated analysis and calibration program in Python. Preliminary analysis shows spatial resolutions less than 1mm and measures an electron density of ne = 1 ×1016 cm-3 in an atmospheric microwave torch. Work supported by DOE contract DE-AC02-09CH11466.

Individual Component Map of Rotatory Strength (ICM-RS) and Rotatory Strength Density (RSD) plots as analysis tools of circular dicroism spectra of complex systems.

PubMed

Chang, Le; Baseggio, Oscar; Sementa, Luca; Cheng, Daojian; Fronzoni, Giovanna; Toffoli, Daniele; Aprà, Edoardo; Stener, Mauro; Fortunelli, Alessandro

2018-06-13

We introduce Individual Component Maps of Rotatory Strength (ICM-RS) and Rotatory Strength Density (RSD) plots as analysis tools of chiro-optical linear response spectra deriving from time-dependent density functional theory (TDDFT) simulations. ICM-RS and RSD allow one to visualize the origin of chiro-optical response in momentum or real space, including signed contributions and therefore highlighting cancellation terms that are ubiquitous in chirality phenomena, and should be especially useful in analyzing the spectra of complex systems. As test cases, we use ICM-RS and RSD to analyze circular dichroism spectra of selected (Ag-Au)30(SR)18 monolayer-protected metal nanoclusters, showing the potential of the proposed tools to derive insight and understanding, and eventually rational design, in chiro-optical studies of complex systems.

Finite element analysis of cylinder shell resonator and design of intelligent density meter

NASA Astrophysics Data System (ADS)

W, Sui X.; M, Fan Y.; X, Zhang G.; R, Qiu Z.

2005-01-01

On the basis of the mathematical model and finite element analysis of the cylinder shell resonator, a novel resonant liquid density meter is designed. The meter consists of a cylinder shell resonator fixed on both ends, a measurement circuit with automatic gain control and automatic phase control, and a signal processing system with microcomputer unit C8051F021. The density meter is insensitive to the liquid pressure, and it can intelligently compensate for the temperature. The experiment results show the meter characteristic coefficients of K0, K1, and K2 at 25 centigrade are -129.5668 kg m-3, -0.2535 × 106 kg m-3 s-1 and 0.6239 × 1010 kg m-3 s-2, respectively. The accuracy of the sensor is ±0.1% in range of 700-900 kg m-3

Electron dynamics inside a vacuum tube diode through linear differential equations

NASA Astrophysics Data System (ADS)

González, Gabriel; Orozco, Fco. Javier González; Orozco

2014-04-01

In this paper we analyze the motion of charged particles in a vacuum tube diode by solving linear differential equations. Our analysis is based on expressing the volume charge density as a function of the current density and coordinates only, i.e. ρ=ρ(J,z), while in the usual scheme the volume charge density is expressed as a function of the current density and electrostatic potential, i.e. ρ=ρ(J,V). We show that, in the case of slow varying charge density, the space-charge-limited current is reduced up to 50%. Our approach gives the well-known behavior of the classical current density proportional to the three-halves power of the bias potential and inversely proportional to the square of the gap distance between electrodes, and does not require the solution of the nonlinear differential equation normally associated with the Child-Langmuir formulation.

Quantification of Pulmonary Fibrosis in a Bleomycin Mouse Model Using Automated Histological Image Analysis.

PubMed

Gilhodes, Jean-Claude; Julé, Yvon; Kreuz, Sebastian; Stierstorfer, Birgit; Stiller, Detlef; Wollin, Lutz

2017-01-01

Current literature on pulmonary fibrosis induced in animal models highlights the need of an accurate, reliable and reproducible histological quantitative analysis. One of the major limits of histological scoring concerns the fact that it is observer-dependent and consequently subject to variability, which may preclude comparative studies between different laboratories. To achieve a reliable and observer-independent quantification of lung fibrosis we developed an automated software histological image analysis performed from digital image of entire lung sections. This automated analysis was compared to standard evaluation methods with regard to its validation as an end-point measure of fibrosis. Lung fibrosis was induced in mice by intratracheal administration of bleomycin (BLM) at 0.25, 0.5, 0.75 and 1 mg/kg. A detailed characterization of BLM-induced fibrosis was performed 14 days after BLM administration using lung function testing, micro-computed tomography and Ashcroft scoring analysis. Quantification of fibrosis by automated analysis was assessed based on pulmonary tissue density measured from thousands of micro-tiles processed from digital images of entire lung sections. Prior to analysis, large bronchi and vessels were manually excluded from the original images. Measurement of fibrosis has been expressed by two indexes: the mean pulmonary tissue density and the high pulmonary tissue density frequency. We showed that tissue density indexes gave access to a very accurate and reliable quantification of morphological changes induced by BLM even for the lowest concentration used (0.25 mg/kg). A reconstructed 2D-image of the entire lung section at high resolution (3.6 μm/pixel) has been performed from tissue density values allowing the visualization of their distribution throughout fibrotic and non-fibrotic regions. A significant correlation (p<0.0001) was found between automated analysis and the above standard evaluation methods. This correlation establishes automated analysis as a novel end-point measure of BLM-induced lung fibrosis in mice, which will be very valuable for future preclinical drug explorations.

Quantification of Pulmonary Fibrosis in a Bleomycin Mouse Model Using Automated Histological Image Analysis

PubMed Central

Gilhodes, Jean-Claude; Kreuz, Sebastian; Stierstorfer, Birgit; Stiller, Detlef; Wollin, Lutz

2017-01-01

Current literature on pulmonary fibrosis induced in animal models highlights the need of an accurate, reliable and reproducible histological quantitative analysis. One of the major limits of histological scoring concerns the fact that it is observer-dependent and consequently subject to variability, which may preclude comparative studies between different laboratories. To achieve a reliable and observer-independent quantification of lung fibrosis we developed an automated software histological image analysis performed from digital image of entire lung sections. This automated analysis was compared to standard evaluation methods with regard to its validation as an end-point measure of fibrosis. Lung fibrosis was induced in mice by intratracheal administration of bleomycin (BLM) at 0.25, 0.5, 0.75 and 1 mg/kg. A detailed characterization of BLM-induced fibrosis was performed 14 days after BLM administration using lung function testing, micro-computed tomography and Ashcroft scoring analysis. Quantification of fibrosis by automated analysis was assessed based on pulmonary tissue density measured from thousands of micro-tiles processed from digital images of entire lung sections. Prior to analysis, large bronchi and vessels were manually excluded from the original images. Measurement of fibrosis has been expressed by two indexes: the mean pulmonary tissue density and the high pulmonary tissue density frequency. We showed that tissue density indexes gave access to a very accurate and reliable quantification of morphological changes induced by BLM even for the lowest concentration used (0.25 mg/kg). A reconstructed 2D-image of the entire lung section at high resolution (3.6 μm/pixel) has been performed from tissue density values allowing the visualization of their distribution throughout fibrotic and non-fibrotic regions. A significant correlation (p<0.0001) was found between automated analysis and the above standard evaluation methods. This correlation establishes automated analysis as a novel end-point measure of BLM-induced lung fibrosis in mice, which will be very valuable for future preclinical drug explorations. PMID:28107543

Investigating the Role of Gravity Wave on Equatorial Ionospheric Irregularities using SABER and C/NOFS Satellites Observations

NASA Astrophysics Data System (ADS)

Nigussie, M.; Damtie, B.; Moldwin, M.; Yizengaw, E.; Tesema, F.; Tebabal, A.

2017-12-01

Theoretical simulations have shown that gravity wave (GW) seeded perturbations amplified by Rayleigh-Taylor Instability (RTI) results in ESF (equatorial spread F); however, there have been limited observational studies using simultaneous observations of GW and ionospheric parameters. In this paper, for the fist time, simultaneous atmospheric temperature perturbation profiles that are due to GWs obtained from Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on-board the TIMED satellite and equatorial in -situ ion density and vertical plasma drift velocity observations with and without ESF activity obtained from C/NOFS satellites are used to investigate the effect of GW on the generation of ESF. The horizontal and vertical wavelengths of ionospheric oscillations and GWs respectively have been estimated applying wavelet transforms. Cross wavelet analysis has also been applied between two closely observed profiles of temperature perturbations to estimate the horizontal wavelength of the GWs. Moreover, vertically propagating GWs that dissipate energy at the upper atmosphere have been investigated using spectral analysis compared with theoretical results. The analysis show that when the ion density shows strong post sunset irregularity between 20 and 24 LT, vertically upward drift velocities increase between 17 and 19 LT, but it becomes vertically downward when the ion density shows smooth variation. The horizontal wavelengths estimated from C/NOFS and SABER observations show excellent agreement when ion density observations show strong fluctuations; otherwise, they have poor agreement. It is also found that altitude profiles of potential energy of GW increases up to 90 km and then decreases significantly. It is found that the vertical wavelength of GW, corresponding to the dominant spectral power, ranges from about 7 km to 20 km regardless of the situation of the ionosphere; however, GWs with vertical wavelengths between 100 m to 1 km are found to be saturated between 90 and 110 km whether the ionosphere exhibits irregularity or not. The above results imply that ESF is due to the amplification of perturbations as a result of energy dissipation from GW with vertical wavelength 100 m to 1 km by the RTI that is mainly controlled by Pre-Reversal Enhancement of the zonal electric field.

Acoustic property reconstruction of a neonate Yangtze finless porpoise's (Neophocaena asiaeorientalis) head based on CT imaging.

PubMed

Wei, Chong; Wang, Zhitao; Song, Zhongchang; Wang, Kexiong; Wang, Ding; Au, Whitlow W L; Zhang, Yu

2015-01-01

The reconstruction of the acoustic properties of a neonate finless porpoise's head was performed using X-ray computed tomography (CT). The head of the deceased neonate porpoise was also segmented across the body axis and cut into slices. The averaged sound velocity and density were measured, and the Hounsfield units (HU) of the corresponding slices were obtained from computed tomography scanning. A regression analysis was employed to show the linear relationships between the Hounsfield unit and both sound velocity and density of samples. Furthermore, the CT imaging data were used to compare the HU value, sound velocity, density and acoustic characteristic impedance of the main tissues in the porpoise's head. The results showed that the linear relationships between HU and both sound velocity and density were qualitatively consistent with previous studies on Indo-pacific humpback dolphins and Cuvier's beaked whales. However, there was no significant increase of the sound velocity and acoustic impedance from the inner core to the outer layer in this neonate finless porpoise's melon.

Chaotic density fluctuations in L-mode plasmas of the DIII-D tokamak

DOE PAGES

Maggs, J. E.; Rhodes, Terry L.; Morales, G. J.

2015-03-05

Analysis of the time series obtained with the Doppler backscattering system (DBS) in the DIII-D tokamak shows that intermediate wave number plasma density fluctuations in low confinement (L-mode) tokamak plasmas are chaotic. Here, the supporting evidence is based on the shape of the power spectrum; the location of the signal in the complexity-entropy plane (C-H plane); and the population of the corresponding Bandt-Pompe probability distributions.

[Influence of sample surface roughness on mathematical model of NIR quantitative analysis of wood density].

PubMed

Huang, An-Min; Fei, Ben-Hua; Jiang, Ze-Hui; Hse, Chung-Yun

2007-09-01

Near infrared spectroscopy is widely used as a quantitative method, and the main multivariate techniques consist of regression methods used to build prediction models, however, the accuracy of analysis results will be affected by many factors. In the present paper, the influence of different sample roughness on the mathematical model of NIR quantitative analysis of wood density was studied. The result of experiments showed that if the roughness of predicted samples was consistent with that of calibrated samples, the result was good, otherwise the error would be much higher. The roughness-mixed model was more flexible and adaptable to different sample roughness. The prediction ability of the roughness-mixed model was much better than that of the single-roughness model.

Digital radiographic evaluation of alveolar bone loss, density and lamina dura integrity on post splinting mandibular anterior with chronic periodontitis

NASA Astrophysics Data System (ADS)

Rafini, F.; Priaminiarti, M.; Sukardi, I.; Lessang, R.

2017-08-01

The healing of periodontal splinting can be detected both with clinical and radiographic examination. In this study, the alveolar bone was evaluated by radiographic digital periapical analysis. Periodontal tooth splinting is periodontal support therapy used to prevent periodontal injury during repair and regeneration of periodontal therapy. Radiographic digital periapical analysis of alveolar bone in the mandibular anterior region with chronic periodontitis and 2/3 cervical bone loss after three months of periodontal splinting. Eighty four proximal site (43 mesial and 41 distal) from 16 patients with chronic periodontitis and treated with spinting were examined by taking periapical digital radiographic at day 1 and 91. The bone loss, bone density and utility of lamina dura were evaluated. The statistical analysis after three months evaluation using T-test for bone loss, Wilcoxon sign rank test for bone density and utility lamina dura showed no significantly differences (p<0.05) (p=0.44, 0.256 and 0.059). No radiographic change in bone loss, bone density and utility of lamina dura from chronic periodontitis with 2/3 alveolar bone loss after three months splinting.

Breast density quantification with cone-beam CT: A post-mortem study

PubMed Central

Johnson, Travis; Ding, Huanjun; Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

2014-01-01

Forty post-mortem breasts were imaged with a flat-panel based cone-beam x-ray CT system at 50 kVp. The feasibility of breast density quantification has been investigated using standard histogram thresholding and an automatic segmentation method based on the fuzzy c-means algorithm (FCM). The breasts were chemically decomposed into water, lipid, and protein immediately after image acquisition was completed. The percent fibroglandular volume (%FGV) from chemical analysis was used as the gold standard for breast density comparison. Both image-based segmentation techniques showed good precision in breast density quantification with high linear coefficients between the right and left breast of each pair. When comparing with the gold standard using %FGV from chemical analysis, Pearson’s r-values were estimated to be 0.983 and 0.968 for the FCM clustering and the histogram thresholding techniques, respectively. The standard error of the estimate (SEE) was also reduced from 3.92% to 2.45% by applying the automatic clustering technique. The results of the postmortem study suggested that breast tissue can be characterized in terms of water, lipid and protein contents with high accuracy by using chemical analysis, which offers a gold standard for breast density studies comparing different techniques. In the investigated image segmentation techniques, the FCM algorithm had high precision and accuracy in breast density quantification. In comparison to conventional histogram thresholding, it was more efficient and reduced inter-observer variation. PMID:24254317

Bearing failure detection of micro wind turbine via power spectral density analysis for stator current signals spectrum

NASA Astrophysics Data System (ADS)

Mahmood, Faleh H.; Kadhim, Hussein T.; Resen, Ali K.; Shaban, Auday H.

2018-05-01

The failure such as air gap weirdness, rubbing, and scrapping between stator and rotor generator arise unavoidably and may cause extremely terrible results for a wind turbine. Therefore, we should pay more attention to detect and identify its cause-bearing failure in wind turbine to improve the operational reliability. The current paper tends to use of power spectral density analysis method of detecting internal race and external race bearing failure in micro wind turbine by estimation stator current signal of the generator. The failure detector method shows that it is well suited and effective for bearing failure detection.

Gravity-driven soap film dynamics in subcritical regimes

NASA Astrophysics Data System (ADS)

Auliel, M. I.; Castro, F.; Sosa, R.; Artana, G.

2015-10-01

We undertake the analysis of soap-film dynamics with the classical approach of asymptotic expansions. We focus our analysis in vertical soap film tunnels operating in subcritical regimes with elastic Mach numbers Me=O(10-1) . Considering the associated set of nondimensional numbers that characterize this flow, we show that the flow behaves as a two-dimensional (2D) divergence free flow with variable mass density. When the soap film dynamics agrees with that of a 2D and almost constant mass density flow, the regions where the second invariant of the velocity gradient is non-null correspond to regions where the rate of change of film thickness is non-negligible.

Vibrational Spectra and Density functional calculation of Organic Nonlinear Optic Crystal p-Amino Acetanilide

NASA Astrophysics Data System (ADS)

Saja, D.; Joe, I. Hubert; Jayakumar, V. S.

2006-01-01

The NIR-FT Raman, FT-IR spectral analysis of potential NLO material P-Amino Acetanilide is carried out by density functional computations. The optimized geometry shows that NH2 and NHCOCH3 groups substituted in para position of phenyl ring are non-planar which predicts maximum conjugation of molecule with donor and acceptor groups. Vibrational analysis reveals that simultaneous IR and Raman activation of the phenyl ring modes also provide evidence for the charge transfer interaction between the donors and the acceptor can make the molecule highly polarized and the intra molecular charge transfer interaction must be responsible for the NLO properties of PAA.

Molecular mechanics and structure of the fluid-solid interface in simple fluids

NASA Astrophysics Data System (ADS)

Wang, Gerald J.; Hadjiconstantinou, Nicolas G.

2017-09-01

Near a fluid-solid interface, the fluid spatial density profile is highly nonuniform at the molecular scale. This nonuniformity can have profound effects on the dynamical behavior of the fluid and has been shown to play an especially important role when modeling a wide variety of nanoscale heat and momentum transfer phenomena. We use molecular-mechanics arguments and molecular-dynamics (MD) simulations to develop a better understanding of the structure of the first fluid layer directly adjacent to the solid in the layering regime, as delineated by a nondimensional number that compares the effects of wall-fluid interaction to thermal energy. Using asymptotic analysis of the Nernst-Planck equation, we show that features of the fluid density profile close to the wall, such as the areal density of the first layer ΣFL (defined as the number of atoms in this layer per unit of fluid-solid interfacial area), can be expressed as polynomial functions of the fluid average density ρave. This is found to be in agreement with MD simulations, which also show that the width of the first layer hFL is a linear function of the average density and only a weak function of the temperature T . These results can be combined to show that, for system average densities corresponding to a dense fluid (ρave≥0.7 ), the ratio C ≡ΣFLρavehFL, representing a density enhancement with respect to the bulk fluid, depends only weakly on temperature and is essentially independent of density. Further MD simulations suggest that the above results, nominally valid for large systems (solid in contact with semi-infinite fluid), also describe fluid-solid interfaces under considerable nanoconfinement, provided ρave is appropriately defined.

The Diurnal Cycle of Particle Sizes, Compositions, and Densities observed in Sacramento, CA during CARES Field Campaign

NASA Astrophysics Data System (ADS)

Beránek, J.; Vaden, T.; Imre, D. G.; Zelenyuk, A.

2010-12-01

A central objective of the Carbonaceous Aerosol and Radiative Effects Study (CARES) was to characterize unequivocally all aspects related to organics in aerosols. To this end, a range of instruments measured loadings, size distributions, compositions, densities, CCN activities, and optical properties of aerosol sampled in Sacramento, CA over the month of June 2010. We present the results of measurements conducted by our single particle mass spectrometer, SPLAT. SPLAT was used to measure the size, composition, and density of individual particles with diameters between 50 to 2000 nm. SPLAT measured the vacuum aerodynamic diameters (dva) of more than 2 million particles and the compositions of ~350,000 particles, each day. In addition, SPLAT was used in combination with a differential mobility analyzer to measure the density, or effective density of individual particles. These measurements were typically conducted twice per day: in the morning, and mid-afternoon. Preliminary analysis of the data shows that under most conditions, the particles were relatively small (below 200 nm), and the vast majority of them were composed of oxygenated organics mixed with various amounts of sulfates. Analysis of the mass spectra shows that the oxygenated organics in these particles are the oxidized products of biogenic volatile organic precursors. In addition to particles composed of SOA mixed with sulfates, we detected and characterized fresh and processed soot particles, biomass burning aerosol, organic amines, sea salt - fresh and processed - and a small number of dust and other inorganic particles, commonly found in urban environment. SOA mixed with sulfates were the vast majority of particles at all times, while the other particle types exhibited episodic behavior. The data shows a reproducible diurnal pattern in SOA size distributions, number concentrations, and compositions. Early in the morning the particle number concentrations are relatively low, and the particle size distributions peak at ~70 nm. Smaller particles (80 nm) have a density of 1.3 g cm<-3/sup>, while the density of larger particles (200 nm) is 1.6 g cm<-3/sup>. The mass spectra show that the smaller particles are composed of organics mixed with ~10% of sulfates and larger ones contain mostly sulfate with a small amount of organics. As biogenic emissions are processed, nucleation events lead to a large increase in the concentrations of very small particles. As the day progresses particle number concentrations increase and particles grow. By mid-afternoon, these particles are sufficiently large to be characterized by SPLAT. At this point, the density of 80 to 200 nm particles is ~1.3 g cm<-3/sup>. These particles are composed of oxygenated organics mixed with a ~10% sulfate. A detailed analysis of the mass spectra shows that there are two types of SOA particles, which we labeled Type 43 and Type 44, to indicate which of the two peaks caries more intensity in the individual particle mass spectra. Interestingly, we find evidence to suggest that in both particle types a large fraction of the intensity in peaks 44 and 73 is related to surface compound.

Ultraviolet observations of cool stars. V - The local density of interstellar matter

NASA Technical Reports Server (NTRS)

Mcclintock, W.; Henry, R. C.; Moos, H. W.; Linsky, J. L.

1976-01-01

A high-resolution Copernicus observation of the chromospheric Ly-alpha emission line of the nearby (3.3 pc) K dwarf epsilon Eri sets limits on the velocity, the velocity dispersion, and the density of atomic hydrogen in the local interstellar medium. Analysis shows that the interstellar Ly-alpha absorption is on the flat portion of the curve of growth. An upper limit of 0.12 per cu cm is derived for the atomic-hydrogen density. The value of this density is 0.08 (plus or minus 0.04 per cu cm if the velocity-dispersion parameter is 9 km/s, corresponding to a temperature of 5000 K. Also, the interstellar deuterium Ly-alpha line may be present in the spectrum.

Molecular orbital studies (hardness, chemical potential, electronegativity and electrophilicity), vibrational spectroscopic investigation and normal coordinate analysis of 5-{1-hydroxy-2-[(propan-2-yl)amino]ethyl}benzene-1,3-diol

NASA Astrophysics Data System (ADS)

Muthu, S.; Renuga, S.

2014-01-01

FT-IR and FT-Raman spectra of 5-{1-hydroxy-2-[(propan-2-yl) amino] ethyl} benzene-1,3-diol (abbrevi- 54 ated as HPAEBD) were recorded in the region 4000-450 cm-1 and 4000-100 cm-1 respectively. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (B3LYP) and HF method with 6-31 G(d,p) as basis set. The theoretical wave numbers were scaled and compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated Potential energy distribution (PED). Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the σ antibonding orbitals and E (2) energies confirm the occurrence of intra molecular charge transfer (ICT) within the molecule. The molecule orbital contributions were studied by using the total (TDOS), sum of α and β electron (αβDOS) density of States. Mulliken population analysis of atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in this compound. On the basis of vibrational analyses, the thermodynamic properties of title compound at different temperatures have been calculated.

Effect of the hydration temperature on the microstructure of Class G cement: C-S-H composition and density

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

Bahafid, Sara; Ghabezloo, Siavash; Duc, Myriam

Curing temperature has a significant influence on cement paste microstructure and the properties of its principal hydrate C-S-H. In this paper, the effect of the hydration temperature in the range of 7 °C to 90 °C on the microstructure of a class G oil-well cement is studied. This is done by combining various experimental methods, including X-ray diffraction associated with the Rietveld analysis, thermo-gravimetric analysis, mercury intrusion porosimetry and porosity evaluation by drying. The experimental results show an increase of the capillary porosity and a decrease of the gel porosity by increasing the hydration temperature. This is attributed to amore » decrease of the C-S-H intrinsic porosity and a corresponding increase of the C-S-H density for higher curing temperatures. The experimental results are used in a simple analysis method to evaluate the density of C-S-H, as well as its C/S ratio and H/S ratio in dry and saturated conditions. The evaluated C-S-H density varies from 1.88 g/cm{sup 3} at 7 °C to 2.10 g/cm{sup 3} at 90 °C. The results also show a decrease of molar C/S ratio with increasing hydration temperature from 1.93 at 7 °C to 1.71 at 90 °C and of the H/S ratio from 5.1 at 7 °C to 2.66 at 90 °C.« less

Quantitative immunohistochemistry of factor VIII-related antigen in breast carcinoma: a comparison of computer-assisted image analysis with established counting methods.

PubMed

Kohlberger, P D; Obermair, A; Sliutz, G; Heinzl, H; Koelbl, H; Breitenecker, G; Gitsch, G; Kainz, C

1996-06-01

Microvessel density in the area of the most intense neovascularization in invasive breast carcinoma is reported to be an independent prognostic factor. The established method of enumeration of microvessel density is to count the vessels using an ocular raster (counted microvessel density [CMVD]). The vessels were detected by staining endothelial cells using Factor VIII-related antigen. The aim of the study was to compare the CMVD results with the percentage of factor VIII-related antigen-stained area using computer-assisted image analysis. A true color red-green-blue (RGB) image analyzer based on a morphologically reduced instruction set computer processor was used to evaluate the area of stained endothelial cells. Sixty invasive breast carcinomas were included in the analysis. There was no significant correlation between the CMVD and the percentage of factor VIII-related antigen-stained area (Spearman correlation coefficient = 0.24, confidence interval = 0.02-0.46). Although high CMVD was significantly correlated with poorer recurrence free survival (P = .024), percentage of factor VIII-related antigen-stained area showed no prognostic value. Counted microvessel density and percentage of factor VIII-related antigen-stained area showed a highly significant correlation with vessel invasion (P = .0001 and P = .02, respectively). There was no correlation between CMVD and percentage of factor VIII-related antigen-stained area with other prognostic factors. In contrast to the CMVD within malignant tissue, the percentage of factor VIII-related antigen-stained area is not suitable as an indicator of prognosis in breast cancer patients.

Characterization of shredded television scrap and implications for materials recovery.

PubMed

Cui, Jirang; Forssberg, Eric

2007-01-01

Characterization of TV scrap was carried out by using a variety of methods, such as chemical analysis, particle size and shape analysis, liberation degree analysis, thermogravimetric analysis, sink-float test, and IR spectrometry. A comparison of TV scrap, personal computer scrap, and printed circuit board scrap shows that the content of non-ferrous metals and precious metals in TV scrap is much lower than that in personal computer scrap or printed circuit board scrap. It is expected that recycling of TV scrap will not be cost-effective by utilizing conventional manual disassembly. The result of particle shape analysis indicates that the non-ferrous metal particles in TV scrap formed as a variety of shapes; it is much more heterogeneous than that of plastics and printed circuit boards. Furthermore, the separability of TV scrap using density-based techniques was evaluated by the sink-float test. The result demonstrates that a high recovery of copper could be obtained by using an effective gravity separation process. Identification of plastics shows that the major plastic in TV scrap is high impact polystyrene. Gravity separation of plastics may encounter some challenges in separation of plastics from TV scrap because of specific density variations.

Analysis of dental supportive structures in orthodontic therapy.

PubMed

Pavicin, Ivana Savić; Ivosević-Magdalenić, Natasa; Badel, Tomislav; Basić, Kresimir; Keros, Jadranka

2012-09-01

The purpose was to define the impact of orthodontic appliances on the density of the underlying dental bone tissue. Radiographic images of teeth were made in 27 study subjects before and twelve months after fixed orthodontic appliances were carried. The radiographs were digitalized and the levels of gray at sites where the greatest bone resorption was expected were transformed into optic density. In the standardization and comparison of values from the first and the second measurements the copper calibration wedge--a stepwedge--was used. Optic densities in the observed sites were compared with optic densities of the calibration wedge and expressed as their thickness equivalent. The study results showed no statistically significant difference in bone densities, indicating that the orthodontic therapy was properly planned and carried out and that excessive forces were not used in the applied correctional procedures.

The role of density discontinuity in the inviscid instability of two-phase parallel flows

NASA Astrophysics Data System (ADS)

Behzad, M.; Ashgriz, N.

2014-02-01

We re-examine the inviscid instability of two-phase parallel flows with piecewise linear velocity profiles. Although such configuration has been theoretically investigated, we employ the concept of waves resonance to physically interpret the instability mechanism as well as the essential role of density discontinuity in the flow. Upon performing linear stability analysis, we demonstrate the existence of neutrally stable "density" and "density-vorticity" waves which are emerged due to the density jump in the flow, in addition to the well-known vorticity waves. Such waves are capable of resonating with each other to form unstable modes in the flow. Although unstable modes in this study are classified as the "shear instability" type, we demonstrate that they are not necessarily of the Rayleigh type. The results also show that the density can have both stabilizing and destabilizing effects on the flow stability. We verify that the difference in the resonating pair of neutral waves leads to such distinct behavior of the density variation.

Time-delayed behaviors of transient four-wave mixing signal intensity in inverted semiconductor with carrier-injection pumping

NASA Astrophysics Data System (ADS)

Hu, Zhenhua; Gao, Shen; Xiang, Bowen

2016-01-01

An analytical expression of transient four-wave mixing (TFWM) in inverted semiconductor with carrier-injection pumping was derived from both the density matrix equation and the complex stochastic stationary statistical method of incoherent light. Numerical analysis showed that the TFWM decayed decay is towards the limit of extreme homogeneous and inhomogeneous broadenings in atoms and the decaying time is inversely proportional to half the power of the net carrier densities for a low carrier-density injection and other high carrier-density injection, while it obeys an usual exponential decay with other decaying time that is inversely proportional to half the power of the net carrier density or it obeys an unusual exponential decay with the decaying time that is inversely proportional to a third power of the net carrier density for a moderate carrier-density injection. The results can be applied to studying ultrafast carrier dephasing in the inverted semiconductors such as semiconductor laser amplifier and semiconductor optical amplifier.

Optical and electronic properties of sub-surface conducting layers in diamond created by MeV B-implantation at elevated temperatures

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

Willems van Beveren, L. H., E-mail: laurensw@unimelb.edu.au; Bowers, H.; Ganesan, K.

2016-06-14

Boron implantation with in-situ dynamic annealing is used to produce highly conductive sub-surface layers in type IIa (100) diamond plates for the search of a superconducting phase transition. Here, we demonstrate that high-fluence MeV ion-implantation, at elevated temperatures avoids graphitization and can be used to achieve doping densities of 6 at. %. In order to quantify the diamond crystal damage associated with implantation Raman spectroscopy was performed, demonstrating high temperature annealing recovers the lattice. Additionally, low-temperature electronic transport measurements show evidence of charge carrier densities close to the metal-insulator-transition. After electronic characterization, secondary ion mass spectrometry was performed to mapmore » out the ion profile of the implanted plates. The analysis shows close agreement with the simulated ion-profile assuming scaling factors that take into account an average change in diamond density due to device fabrication. Finally, the data show that boron diffusion is negligible during the high temperature annealing process.« less

Application of calculated NMR parameters, aromaticity indices and wavefunction properties for evaluation of corrosion inhibition efficiency of pyrazine inhibitors

NASA Astrophysics Data System (ADS)

Behzadi, Hadi; Manzetti, Sergio; Dargahi, Maryam; Roonasi, Payman; Khalilnia, Zahra

2018-01-01

In light of the importance of developing novel corrosion inhibitors, a series of quantum chemical calculations were carried out to evaluate 15N chemical shielding CS tensors as well as aromaticity indexes including NICS, HOMA, FLU, and PDI of three pyrazine derivatives, 2-methylpyrazine (MP), 2-aminopyrazine (AP) and 2-amino-5-bromopyrazine (ABP). The NICS parameters have been shown in previous studies to be paramount to the prediction of anti-corrosion properties, and have been combined here with HOMA, FLU and PDI and detailed wavefunction analysis to determine the effects from bromination and methylation on pyrazine. The results show that the electron density around the nitrogens, represented by CS tensors, can be good indicators of anti-corrosion efficiency. Additionally, the NICS, FLU and PDI, as aromaticity indicators of molecule, are well correlated with experimental corrosion inhibition efficiencies of the studied inhibitors. Bader sampling and detailed wavefunction analysis shows that the major effects from bromination on the pyrazine derivatives affect the Laplacian of the electron density of the ring, delocalizing the aromatic electrons of the carbon atoms into lone pairs and increasing polarization of the Laplacian values. This feature is well agreement with empirical studies, which show that ABP is the most efficient anti-corrosion compound followed by AP and MP, a property which can be attributed and predicted by derivation of the Laplacian of the electron density of the ring nuclei. This study shows the importance of devising DFT methods for development of new corrosion inhibitors, and the strength of electronic and nuclear analysis, and depicts most importantly how corrosion inhibitors composed of aromatic moieties may be modified to increase anti-corrosive properties.

Topology of the electron density of d0 transition metal compounds at subatomic resolution.

PubMed

Batke, Kilian; Eickerling, Georg

2013-11-14

Accurate X-ray diffraction experiments allow for a reconstruction of the electron density distribution of solids and molecules in a crystal. The basis for the reconstruction of the electron density is in many cases a multipolar expansion of the X-ray scattering factors in terms of spherical harmonics, a so-called multipolar model. This commonly used ansatz splits the total electron density of each pseudoatom in the crystal into (i) a spherical core, (ii) a spherical valence, and (iii) a nonspherical valence contribution. Previous studies, for example, on diamond and α-silicon have already shown that this approximation is no longer valid when ultrahigh-resolution diffraction data is taken into account. We report here the results of an analysis of the calculated electron density distribution in the d(0) transition metal compounds [TMCH3](2+) (TM = Sc, Y, and La) at subatomic resolution. By a detailed molecular orbital analysis, it is demonstrated that due to the radial nodal structure of the 3d, 4d, and 5d orbitals involved in the TM-C bond formation a significant polarization of the electron density in the inner electronic shells of the TM atoms is observed. We further show that these polarizations have to be taken into account by an extended multipolar model in order to recover accurate electron density distributions from high-resolution structure factors calculated for the title compounds.

An analysis of OH excited state absorption lines in DR 21 and K3-50

NASA Astrophysics Data System (ADS)

Jones, K. N.; Doel, R. C.; Field, D.; Gray, M. D.; Walker, R. N. F.

1992-10-01

We present an analysis of the OH absorption line zones observed toward the compact H II regions DR 21 and K3-50. Using as parameters the kinetic and dust temperatures, the H2 number density and the ratio of OH-H2 number densities to the velocity gradient, the model quantitatively reproduces the absorption line data for the six main line transitions in 2 Pi3/2 J = 5/2, 7/2, and 9/2. Observed upper limits for the absorption or emission in the satellite lines of 2 Pi3/2 J = 5/2 are crucial in constraining the range of derived parameters. Physical conditions derived for DR 21 show that the kinetic temperature centers around 140 K, the H2 number density around 10 exp 7/cu cm, and that the OH column density in the excited state absorption zone lies between 1 x 10 exp 15/sq cm and 2 x 10 exp 15/sq cm. Including contributions from a J = 3/2 absorption zone, the total OH column density is more than a factor of 2 lower than estimates based upon LTE (Walmsley et al., 1986). The OH absorption zone in K3-50 tends toward higher density and displays a larger column density, while the kinetic temperature is similar. For both sources, the dust temperature is found to be significantly lower than the kinetic temperature.

Influence of Stepped Osteotomy on Primary Stability of Implants Inserted in Low-Density Bone Sites: An In Vitro Study.

PubMed

Degidi, Marco; Daprile, Giuseppe; Piattelli, Adriano

The aims of this study were to evaluate the ability of a stepped osteotomy to improve dental implant primary stability in low-density bone sites and to investigate possible correlations between primary stability parameters. The study was performed on fresh humid bovine bone classified as type III. The test group consisted of 30 Astra Tech EV implants inserted following the protocol provided by the manufacturer. The first control group consisted of 30 Astra Tech EV implants inserted in sites without the underpreparation of the apical portion. The second control group consisted of 30 Astra Tech TX implants inserted following the protocol provided by the manufacturer. Implant insertion was performed at the predetermined 30 rpm. The insertion torque data were recorded and exported as a curve; using a trapezoidal integration technique, the area underlying the curve was calculated: this area represents the variable torque work (VTW). Peak insertion torque (pIT) and resonance frequency analysis (RFA) were also recorded. A Mann-Whitney test showed that the mean VTW was significantly higher in the test group compared with the first control and second control groups; furthermore, statistical analysis showed that pIT also was significantly higher in the test group compared with the first and second control groups. Analyzing RFA values, only the difference between the test group and second control group showed statistical significance. Pearson correlation analysis showed a very strong positive correlation between pIT and VTW values in all groups; furthermore, it showed a positive correlation between pIT and RFA values and between VTW and RFA values only in the test group. Within the limitations of an in vitro study, the results show that stepped osteotomy can be a viable method to improve implant primary stability in low-density bone sites, and that, when a traditional osteotomy method is performed, RFA presents no correlation with pIT and VTW.

Trapped Inflation

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

Green, Daniel; Horn, Bart; /SLAC /Stanford U., Phys. Dept.

2009-06-19

We analyze a distinctive mechanism for inflation in which particle production slows down a scalar field on a steep potential, and show how it descends from angular moduli in string compactifications. The analysis of density perturbations - taking into account the integrated effect of the produced particles and their quantum fluctuations - requires somewhat new techniques that we develop. We then determine the conditions for this effect to produce sixty e-foldings of inflation with the correct amplitude of density perturbations at the Gaussian level, and show that these requirements can be straightforwardly satisfied. Finally, we estimate the amplitude of themore » non-Gaussianity in the power spectrum and find a significant equilateral contribution.« less

Grain Boundary Effect on Charge Transport in Pentacene Thin Films

NASA Astrophysics Data System (ADS)

Weis, Martin; Gmucová, Katarína; Nádaždy, Vojtech; Majková, Eva; Haško, Daniel; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

2011-04-01

We report on charge transport properties of polycrystalline pentacene films with variable average grain size in the range from 0.1 to 0.3 µm controlled by the preparation technology. We illustrate with the organic field-effect transistors decrease of the effective mobility and presence of traps with decrease of the grain size. Analysis of the charge transfer excitons reveals decrease of the mobile charge density and the steady-state voltammetry showed significant increase of oxygen- and hydrogen-related defects. We also briefly discuss accumulation of the defects on the grain boundary and show relation between the defect density and grain boundary length.

Changes in Breast Density Reporting Patterns of Radiologists After Publication of the 5th Edition BI-RADS Guidelines: A Single Institution Experience.

PubMed

Irshad, Abid; Leddy, Rebecca; Lewis, Madelene; Cluver, Abbie; Ackerman, Susan; Pavic, Dag; Collins, Heather

2017-10-01

The objective of our study was to determine the impact of 5th edition BI-RADS breast density assessment guidelines on density reporting patterns in our clinical practice. PenRad reporting system was used to collect mammographic breast density data reported by five radiologists: 16,907 density assignments using 5th edition BI-RADS guidelines were compared with 19,066 density assessments using 4th edition guidelines. Changes in the density assessment pattern were noted between the 4th and 5th edition guidelines, and agreement in density distribution was compared using the intraclass correlation coefficient. A chi-square analysis was conducted for each reader to examine the change in the proportion of dense versus nondense assignments and on each category type to examine specific changes in proportion of density assignments from the 4th to the 5th edition. All reported p values are two-sided, and statistical significance was considered at the p < 0.001 threshold. Using the 5th edition, there was an overall 5.0% decrease in fatty assessments (p < 0.001), 2.8% increase in scattered densities (p < 0.001), 2.6% increase in heterogeneously dense (p < 0.001), and 0.4% decrease in extremely dense assessments (p = 0.15). Comparing the dense with nondense categories, there was a 2.3% overall increase in the dense assessments (p < 0.001) using 5th edition guidelines, mainly in the heterogeneously dense category. Two radiologists showed increased dense assessments (p < 0.001) using the 5th edition, and three radiologists showed no change (p = 0.39, 0.67, and 0.76). There was an overall increase in the dense assessments using the 5th edition, but individual radiologists in our clinical practice showed a variable adaptation to new guidelines.

Genome wide analysis of flowering time trait in multiple environments via high-throughput genotyping technique in Brassica napus L.

PubMed

Li, Lun; Long, Yan; Zhang, Libin; Dalton-Morgan, Jessica; Batley, Jacqueline; Yu, Longjiang; Meng, Jinling; Li, Maoteng

2015-01-01

The prediction of the flowering time (FT) trait in Brassica napus based on genome-wide markers and the detection of underlying genetic factors is important not only for oilseed producers around the world but also for the other crop industry in the rotation system in China. In previous studies the low density and mixture of biomarkers used obstructed genomic selection in B. napus and comprehensive mapping of FT related loci. In this study, a high-density genome-wide SNP set was genotyped from a double-haploid population of B. napus. We first performed genomic prediction of FT traits in B. napus using SNPs across the genome under ten environments of three geographic regions via eight existing genomic predictive models. The results showed that all the models achieved comparably high accuracies, verifying the feasibility of genomic prediction in B. napus. Next, we performed a large-scale mapping of FT related loci among three regions, and found 437 associated SNPs, some of which represented known FT genes, such as AP1 and PHYE. The genes tagged by the associated SNPs were enriched in biological processes involved in the formation of flowers. Epistasis analysis showed that significant interactions were found between detected loci, even among some known FT related genes. All the results showed that our large scale and high-density genotype data are of great practical and scientific values for B. napus. To our best knowledge, this is the first evaluation of genomic selection models in B. napus based on a high-density SNP dataset and large-scale mapping of FT loci.

SOL effects on the pedestal structure in DIII-D discharges

DOE PAGES

Sontag, Aaron C.; Chen, Xi; Canik, John; ...

2017-05-24

SOLPS analysis explains the differences in pedestal structure associated with different ion ∇B drift directions in DIII-D. Core transport models predict that fusion power scales roughly as the square of the pressure at the top of the pedestal, so understanding the effects that determine pedestal structure in steady-state operational scenarios is important to projecting scenarios developed in DIII-D to ITER and other devices. Both experiments and modeling indicate that scrape off layer (SOL) conditions are important in optimizing the pedestal structure for high-beta steady-state scenarios. The SOLPS code is used to provide interpretive analysis of the pedestal and SOL tomore » examine the nature of flows and fueling on the pedestal structure including the effects of drifts in the fluid model. This analysis shows that flows driven by the ion ∇B drift are outward when this drift is toward the x-point in a single-null divertor configuration (favorable ∇B direction for reduced H-mode power threshold), and inward when the drift is away from the x-point (unfavorable ∇B direction). It is hypothesized that these flows decrease the density gradient in the pedestal in the favorable direction, thereby stabilizing the kinetic ballooning mode (KBM) and increasing the pedestal width. Comparisons of pedestal structures in similarly shaped DIII-D steady-state plasmas confirm this change, showing increased density pedestal width and lower peak density and lower separatrix density with the favorable drift direction. The pedestal temperature is higher in the lower density case, resulting in an increased pedestal pressure, which indicates that the increased particle flux does not significantly degrade energy confinement. Modeling of cases with constant ∇B drift direction but changing between the more open lower divertor and more closed upper divertor show that there is increased fueling inside the pedestal with the more open geometry. As a result, the pedestal fueling rate for both attached and detached cases is always lower with more closed divertor geometry than in any cases with more open geometry.« less

SOL effects on the pedestal structure in DIII-D discharges

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

Sontag, Aaron C.; Chen, Xi; Canik, John

SOLPS analysis explains the differences in pedestal structure associated with different ion ∇B drift directions in DIII-D. Core transport models predict that fusion power scales roughly as the square of the pressure at the top of the pedestal, so understanding the effects that determine pedestal structure in steady-state operational scenarios is important to projecting scenarios developed in DIII-D to ITER and other devices. Both experiments and modeling indicate that scrape off layer (SOL) conditions are important in optimizing the pedestal structure for high-beta steady-state scenarios. The SOLPS code is used to provide interpretive analysis of the pedestal and SOL tomore » examine the nature of flows and fueling on the pedestal structure including the effects of drifts in the fluid model. This analysis shows that flows driven by the ion ∇B drift are outward when this drift is toward the x-point in a single-null divertor configuration (favorable ∇B direction for reduced H-mode power threshold), and inward when the drift is away from the x-point (unfavorable ∇B direction). It is hypothesized that these flows decrease the density gradient in the pedestal in the favorable direction, thereby stabilizing the kinetic ballooning mode (KBM) and increasing the pedestal width. Comparisons of pedestal structures in similarly shaped DIII-D steady-state plasmas confirm this change, showing increased density pedestal width and lower peak density and lower separatrix density with the favorable drift direction. The pedestal temperature is higher in the lower density case, resulting in an increased pedestal pressure, which indicates that the increased particle flux does not significantly degrade energy confinement. Modeling of cases with constant ∇B drift direction but changing between the more open lower divertor and more closed upper divertor show that there is increased fueling inside the pedestal with the more open geometry. As a result, the pedestal fueling rate for both attached and detached cases is always lower with more closed divertor geometry than in any cases with more open geometry.« less

The effect of initial number of trees per acre and thinning densities on timber yields from red pine plantations in the Lake States.

Treesearch

Allen L. Lundgren

1981-01-01

Describes an analysis of initial density and subsequent thinning options for red pine (Pinus resinosa Ait.) plantations in the Lake States. Results showed that the initial number of established trees per acres has a major impact on the amount and quality of timber product yields, with 200 trees per acre (500/ha) thinned to 120 square feet of basal area per acre (27.5...

Analytical monitoring of soil bioengineering structures in the Tuscan Emilian Apennines of Italy

NASA Astrophysics Data System (ADS)

Selli, Lavinia; Guastini, Enrico

2014-05-01

Soil bioengineering has been an appropriate solution to deal with erosion problems and shallow landslides in the North Apennines, Italy. The objective of our research was a check about critical aspects of soil bioengineering works. We monitored the works that have been carried out in the Tuscan Emilian Apennines by testing the suitability of different plant species and analyzed in detail timber structures of wooden crib walls. Plant species were mainly Salix alba and Salix purpurea that gave good sprouting and survival rates. However, showed some issues in growing on dry and sunny Apennine lands, where other shrubs like Spanish Broom, blackthorn, cornel-tree and Eglantine would be more indicated. The localized analysis on wooden elements has been led gathering parts from the poles and obtaining samples in order to determine their density. The hypothetical initial density of the wood used in the structure has been estimated, then calculating the residual density. This analysis allows us to determine the general condition of the wood, highlighting the structures in worst condition (the one in Pianaccio show a residual density close to 70%, instead of 90% as found on other structures) and those whose degraded wood has undergone the greatest damage (Pianaccio here too, with 50%, followed by Campoferrario - 60% - and by Pian di Favale with 85%, a rather good value for the most degraded wood in the structure).

Analysis of high-resolution foreign exchange data of USD-JPY for 13 years

NASA Astrophysics Data System (ADS)

Mizuno, Takayuki; Kurihara, Shoko; Takayasu, Misako; Takayasu, Hideki

2003-06-01

We analyze high-resolution foreign exchange data consisting of 20 million data points of USD-JPY for 13 years to report firm statistical laws in distributions and correlations of exchange rate fluctuations. A conditional probability density analysis clearly shows the existence of trend-following movements at time scale of 8-ticks, about 1 min.

The impact of stellar feedback on the density and velocity structure of the interstellar medium

NASA Astrophysics Data System (ADS)

Grisdale, Kearn; Agertz, Oscar; Romeo, Alessandro B.; Renaud, Florent; Read, Justin I.

2017-04-01

We study the impact of stellar feedback in shaping the density and velocity structure of neutral hydrogen (H I) in disc galaxies. For our analysis, we carry out ˜4.6 pc resolution N-body+adaptive mesh refinement hydrodynamic simulations of isolated galaxies, set up to mimic a Milky Way and a Large and Small Magellanic Cloud. We quantify the density and velocity structure of the interstellar medium using power spectra and compare the simulated galaxies to observed H I in local spiral galaxies from THINGS (The H I Nearby Galaxy Survey). Our models with stellar feedback give an excellent match to the observed THINGS H I density power spectra. We find that kinetic energy power spectra in feedback-regulated galaxies, regardless of galaxy mass and size, show scalings in excellent agreement with supersonic turbulence (E(k) ∝ k-2) on scales below the thickness of the H I layer. We show that feedback influences the gas density field, and drives gas turbulence, up to large (kpc) scales. This is in stark contrast to density fields generated by large-scale gravity-only driven turbulence. We conclude that the neutral gas content of galaxies carries signatures of stellar feedback on all scales.

Reproducible automated breast density measure with no ionizing radiation using fat-water decomposition MRI.

PubMed

Ding, Jie; Stopeck, Alison T; Gao, Yi; Marron, Marilyn T; Wertheim, Betsy C; Altbach, Maria I; Galons, Jean-Philippe; Roe, Denise J; Wang, Fang; Maskarinec, Gertraud; Thomson, Cynthia A; Thompson, Patricia A; Huang, Chuan

2018-04-06

Increased breast density is a significant independent risk factor for breast cancer, and recent studies show that this risk is modifiable. Hence, breast density measures sensitive to small changes are desired. Utilizing fat-water decomposition MRI, we propose an automated, reproducible breast density measurement, which is nonionizing and directly comparable to mammographic density (MD). Retrospective study. The study included two sample sets of breast cancer patients enrolled in a clinical trial, for concordance analysis with MD (40 patients) and reproducibility analysis (10 patients). The majority of MRI scans (59 scans) were performed with a 1.5T GE Signa scanner using radial IDEAL-GRASE sequence, while the remaining (seven scans) were performed with a 3T Siemens Skyra using 3D Cartesian 6-echo GRE sequence with a similar fat-water separation technique. After automated breast segmentation, breast density was calculated using FraGW, a new measure developed to reliably reflect the amount of fibroglandular tissue and total water content in the entire breast. Based on its concordance with MD, FraGW was calibrated to MR-based breast density (MRD) to be comparable to MD. A previous breast density measurement, Fra80-the ratio of breast voxels with <80% fat fraction-was also calculated for comparison with FraGW. Pearson correlation was performed between MD (reference standard) and FraGW (and Fra80). Test-retest reproducibility of MRD was evaluated using the difference between test-retest measures (Δ 1-2 ) and intraclass correlation coefficient (ICC). Both FraGW and Fra80 were strongly correlated with MD (Pearson ρ: 0.96 vs. 0.90, both P < 0.0001). MRD converted from FraGW showed higher test-retest reproducibility (Δ 1-2 variation: 1.1% ± 1.2%; ICC: 0.99) compared to MD itself (literature intrareader ICC ≤0.96) and Fra80. The proposed MRD is directly comparable with MD and highly reproducible, which enables the early detection of small breast density changes and treatment response. 3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018. © 2018 International Society for Magnetic Resonance in Medicine.

The Robustness Analysis of Wireless Sensor Networks under Uncertain Interference

PubMed Central

Deng, Changjian

2013-01-01

Based on the complex network theory, robustness analysis of condition monitoring wireless sensor network under uncertain interference is present. In the evolution of the topology of sensor networks, the density weighted algebraic connectivity is taken into account, and the phenomenon of removing and repairing the link and node in the network is discussed. Numerical simulation is conducted to explore algebraic connectivity characteristics and network robustness performance. It is found that nodes density has the effect on algebraic connectivity distribution in the random graph model; high density nodes carry more connections, use more throughputs, and may be more unreliable. Moreover, the results show that, when network should be more error tolerant or robust by repairing nodes or adding new nodes, the network should be better clustered in median and high scale wireless sensor networks and be meshing topology in small scale networks. PMID:24363613

Onset of density-driven instabilities in fractured aquifers

NASA Astrophysics Data System (ADS)

Jafari Raad, Seyed Mostafa; Hassanzadeh, Hassan

2018-04-01

Linear stability analysis is conducted to study the onset of density-driven convection involved in solubility trapping of C O2 in fractured aquifers. The effect of physical properties of a fracture network on the stability of a diffusive boundary layer in a saturated fractured porous media is investigated using the dual porosity concept. Linear stability analysis results show that both fracture interporosity flow and fracture storativity play an important role in the stability behavior of the system. It is shown that a diffusive boundary layer under the gravity field in fractured porous media with lower fracture storativity and/or higher fracture interporosity flow coefficient is more stable. We present scaling relations for the onset of convective instability in fractured aquifers with single and variable matrix block size distribution. These findings improve our understanding of density-driven flow in fractured aquifers and are important in the estimation of potential storage capacity, risk assessment, and storage site characterization and screening.

Dynamical and electronic properties of rare-earth aluminides

NASA Astrophysics Data System (ADS)

Sharma, Ramesh; Sharma, Yamini

2018-04-01

Rare-earth dialuminides belong to a large family of compounds that stabilize in cubic MgCu2 structure. A large number of these compounds are superconducting, amongst these YAl2, LaAl2 and LuAl2 have been chosen as reference materials for studying 4f-electron systems. In order to understand the role of the RE atoms, we have applied the FPLAPW and PAW methods within the density functional theory (DFT). Our results show that the contribution of RE atoms is dominant in both electronic structure and phonon dispersion. The anomalous behavior of superconducting LaAl2 is well explained from an analysis of the electron localization function (ELF), Bader charge analysis, density of electronic states as well as the dynamical phonon vibrational modes. The interaction of phonon modes contributed by low frequency vibrations of La atoms with the high density La 5d-states at EF in LaAl2 lead to strong electron-phonon coupling.

The Distribution of Intratumoral Macrophages Correlates with Molecular Phenotypes and Impacts Prognosis in Colorectal Carcinoma.

PubMed

Kim, Younghoon; Wen, Xianyu; Bae, Jeong Mo; Kim, Jung Ho; Cho, Nam-Yun; Kang, Gyeong Hoon

2018-06-15

The role of tumor-associated macrophages (TAMs) in colorectal cancer (CRC) remains elusive. In this study, we aimed to examine the correlation between TAMs, clinicopathological features, tumor-infiltrating lymphocytes (TILs), and prognosis in CRC via image analysis. Immunohistochemical staining for CD68 and CD163 was performed with pan-macrophage and M2-macrophage markers, respectively. Each marker was separately analyzed for intraepithelial and stromal area densities. All four macrophage densities showed a significant correlation with one another (p = 0.001). Intraepithelial CD68+ macrophage densities showed a correlation with pTNM stage (p = 0.008), microsatellite instability (p < 0.001), CpG island methylator phenotype (p < 0.001), and TIL densities (p < 0.001). Intraepithelial CD163+ macrophage densities were associated with perineural invasion, MSI, CIMP, and TIL densities (p < 0.001). Stromal CD68+ and CD163+ macrophage densities had a significant relationship with Intraepithelial and stromal CD3+ (p = 0.001 and p < 0.001, respectively) and CD8+ (p < 0.001) T cells. High intraepithelial CD68+ macrophage density was associated with worse overall survival (HR = 1.386, 95% CI = 1.043-1.843, p = 0.025) and progression-free survival (HR = 1.522, 95% CI = 1.146-2.020, p = 0.004). Intraepithelial CD68+ macrophage density was also an independent prognostic factor of the progression-free survival (HR = 1.447, 95% CI = 1.076-1.947, p = 0.015) of CRC patients regardless of pTNM stage, lymphatic, venous, and perineural invasions, and TIL densities. Our results indicate that the density of intratumoral macrophages are useful prognostic indicator for further stratifying T cell populations in CRC. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Magnetic-Field Density-Functional Theory (BDFT): Lessons from the Adiabatic Connection.

PubMed

Reimann, Sarah; Borgoo, Alex; Tellgren, Erik I; Teale, Andrew M; Helgaker, Trygve

2017-09-12

We study the effects of magnetic fields in the context of magnetic field density-functional theory (BDFT), where the energy is a functional of the electron density ρ and the magnetic field B. We show that this approach is a worthwhile alternative to current-density functional theory (CDFT) and may provide a viable route to the study of many magnetic phenomena using density-functional theory (DFT). The relationship between BDFT and CDFT is developed and clarified within the framework of the four-way correspondence of saddle functions and their convex and concave parents in convex analysis. By decomposing the energy into its Kohn-Sham components, we demonstrate that the magnetizability is mainly determined by those energy components that are related to the density. For existing density functional approximations, this implies that, for the magnetizability, improvements of the density will be more beneficial than introducing a magnetic-field dependence in the correlation functional. However, once a good charge density is achieved, we show that high accuracy is likely only obtainable by including magnetic-field dependence. We demonstrate that adiabatic-connection (AC) curves at different field strengths resemble one another closely provided each curve is calculated at the equilibrium geometry of that field strength. In contrast, if all AC curves are calculated at the equilibrium geometry of the field-free system, then the curves change strongly with increasing field strength due to the increasing importance of static correlation. This holds also for density functional approximations, for which we demonstrate that the main error encountered in the presence of a field is already present at zero field strength, indicating that density-functional approximations may be applied to systems in strong fields, without the need to treat additional static correlation.

Parkinson's disease and the effect of lexical factors on vowel articulation.

PubMed

Watson, Peter J; Munson, Benjamin

2008-11-01

Lexical factors (i.e., word frequency and phonological neighborhood density) influence speech perception and production. It is unknown if these factors are affected by Parkinson's disease (PD). Ten men with PD and ten healthy men read CVC words (varying orthogonally for word frequency and density) aloud while audio recorded. Acoustic analysis was performed on duration and Bark-scaled F1-F2 values of the vowels contained in the words. Vowel space was larger for low-frequency words from dense neighborhoods than from sparse ones for both groups. However, the participants with PD did not show an effect of density on dispersion for high-frequency words.

[Methodological aspects of evaluation of potential lipid capacity for peroxidation from the serum levels of TBA-active products during iron ion stimulation].

PubMed

Kulikova, A I; Tugusheva, F A; Zubina, I M; Shepilova, I N

2008-05-01

The authors propose a simple and reproducible procedure for using iron ions to stimulate serum lipid peroxidation, with TBA-active products being further determined. The procedure determines the reserve of lipids that can be oxidized during oxidative stress. A combination of direct studies and correlation analysis suggests that low-density lipoproteins and very low-density lipoproteins are the major substrates for lipid peroxidation while high-density lipoproteins show a high resistance to this process. The presented procedure may be used to monitor lipid peroxidation in various conditions and upon various exposures in common laboratory practice.

Diffraction enhance x-ray imaging for quantitative phase contrast studies

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

Agrawal, A. K.; Singh, B., E-mail: balwants@rrcat.gov.in; Kashyap, Y. S.

2016-05-23

Conventional X-ray imaging based on absorption contrast permits limited visibility of feature having small density and thickness variations. For imaging of weakly absorbing material or materials possessing similar densities, a novel phase contrast imaging techniques called diffraction enhanced imaging has been designed and developed at imaging beamline Indus-2 RRCAT Indore. The technique provides improved visibility of the interfaces and show high contrast in the image forsmall density or thickness gradients in the bulk. This paper presents basic principle, instrumentation and analysis methods for this technique. Initial results of quantitative phase retrieval carried out on various samples have also been presented.

Inter-Population Variability of Endosymbiont Densities in the Asian Citrus Psyllid (Diaphorina citri Kuwayama).

PubMed

Chu, Chia-Ching; Gill, Torrence A; Hoffmann, Mark; Pelz-Stelinski, Kirsten S

2016-05-01

The Asian citrus psyllid (Diaphorina citri Kuwayama) is an insect pest capable of transmitting Candidatus Liberibacter asiaticus (CLas), the causal agent of citrus greening in North America. D. citri also harbors three endosymbionts, Wolbachia, Candidatus Carsonella ruddii, and Candidatus Profftella armatura, which may influence D. citri physiology and fitness. Although genomic researches on these bacteria have been conducted, much remains unclear regarding their ecology and inter-population variability in D. citri. The present work examined the densities of each endosymbiont in adult D. citri sampled from different populations using quantitative PCR. Under field conditions, the densities of all three endosymbionts positively correlated with each other, and they are associated with D. citri gender and locality. In addition, the infection density of CLas also varied across populations. Although an analysis pooling D. citri from different populations showed that CLas-infected individuals tended to have lower endosymbiont densities compared to uninfected individuals, the difference was not significant when the population was included as a factor in the analysis, suggesting that other population-specific factors may have stronger effects on endosymbiont densities. To determine whether there is a genetic basis to the density differences, endosymbiont densities between aged CLas-negative females of two D. citri populations reared under standardized laboratory conditions were compared. Results suggested that inter-population variability in Wolbachia infection density is associated with the genotypes of the endosymbiont or the host. Findings from this work could facilitate understanding of D. citri-bacterial associations that may benefit the development of approaches for managing citrus greening, such as prevention of CLas transmission.

Comparative study of DPAL and XPAL systems and selection principal of parameters

NASA Astrophysics Data System (ADS)

Huang, Wei; Tan, Rongqing; Li, Zhiyong; Han, Gaoce; Li, Hui

2016-10-01

A theoretical model based on common pump structure is proposed to analyze the laser output characteristics of DPAL (Diode pumped alkali vapor laser) and XPAL (Exciplex pumped alkali laser) in this paper. The model predicts that an optical-to-optical efficiency approaching 80% can be achieved for continuous-wave four- and five-XPAL systems with broadband pumping which is several times of pumped linewidth for DPAL. Operation parameters including pumped intensity, temperature, cell' s length, mixed gas concentration, pumped linewidth and output mirror reflectivity are analyzed for DPAL and XPAL systems basing on the kinetic model. The result shows a better performance in Cs-Ar XPAL laser with requirements of relatively high Ar concentration, high pumped intensity and high temperature. Comparatively, for Cs-DPAL laser, lower temperature and lower pumped intensity should be acquired. In addition, the predictions of selection principal of temperature and cell's length are also presented. The conception of the equivalent "alkali areal density" is proposed in this paper. It is defined as the product of the alkali density and cell's length. The result shows that the output characteristics of DPAL (or XPAL) system with the same alkali areal density but different temperatures turn out to be equal. It is the areal density that reflects the potential of DPAL or XPAL systems directly. A more detailed analysis of similar influences of cavity parameters with the same areal density is also presented. The detailed results of continuous-wave DPAL and XPAL performances as a function of pumped laser linewidth and mixed gas pressure are presented along with an analysis of influences of output coupler.

Reduced quantum dynamics with arbitrary bath spectral densities: hierarchical equations of motion based on several different bath decomposition schemes.

PubMed

Liu, Hao; Zhu, Lili; Bai, Shuming; Shi, Qiang

2014-04-07

We investigated applications of the hierarchical equation of motion (HEOM) method to perform high order perturbation calculations of reduced quantum dynamics for a harmonic bath with arbitrary spectral densities. Three different schemes are used to decompose the bath spectral density into analytical forms that are suitable to the HEOM treatment: (1) The multiple Lorentzian mode model that can be obtained by numerically fitting the model spectral density. (2) The combined Debye and oscillatory Debye modes model that can be constructed by fitting the corresponding classical bath correlation function. (3) A new method that uses undamped harmonic oscillator modes explicitly in the HEOM formalism. Methods to extract system-bath correlations were investigated for the above bath decomposition schemes. We also show that HEOM in the undamped harmonic oscillator modes can give detailed information on the partial Wigner transform of the total density operator. Theoretical analysis and numerical simulations of the spin-Boson dynamics and the absorption line shape of molecular dimers show that the HEOM formalism for high order perturbations can serve as an important tool in studying the quantum dissipative dynamics in the intermediate coupling regime.

Reduced quantum dynamics with arbitrary bath spectral densities: Hierarchical equations of motion based on several different bath decomposition schemes

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

Liu, Hao; Zhu, Lili; Bai, Shuming

2014-04-07

We investigated applications of the hierarchical equation of motion (HEOM) method to perform high order perturbation calculations of reduced quantum dynamics for a harmonic bath with arbitrary spectral densities. Three different schemes are used to decompose the bath spectral density into analytical forms that are suitable to the HEOM treatment: (1) The multiple Lorentzian mode model that can be obtained by numerically fitting the model spectral density. (2) The combined Debye and oscillatory Debye modes model that can be constructed by fitting the corresponding classical bath correlation function. (3) A new method that uses undamped harmonic oscillator modes explicitly inmore » the HEOM formalism. Methods to extract system-bath correlations were investigated for the above bath decomposition schemes. We also show that HEOM in the undamped harmonic oscillator modes can give detailed information on the partial Wigner transform of the total density operator. Theoretical analysis and numerical simulations of the spin-Boson dynamics and the absorption line shape of molecular dimers show that the HEOM formalism for high order perturbations can serve as an important tool in studying the quantum dissipative dynamics in the intermediate coupling regime.« less

Higher sika deer density is associated with higher local abundance of Haemaphysalis longicornis nymphs and adults but not larvae in central Japan.

PubMed

Tsukada, Hideharu; Nakamura, Yoshio; Kamio, Tsugihiko; Inokuma, Hisashi; Hanafusa, Yasuko; Matsuda, Naoko; Maruyama, Tetsuya; Ohba, Takahiro; Nagata, Koji

2014-02-01

Haemaphysalis longicornis (Acari: Ixodidae) is one of the most common and important arthropod disease vectors in Japan, carrying Japanese spotted fever and bovine theileriosis. The recent expansion of sika deer (Cervus nippon, Artiodactyla: Cervidae) populations, the most common wild host of H. longicornis, has also caused concern about increasing the risk of vector-borne diseases in Japan. We used generalized linear mixed model analysis to determine the relative contribution of deer density and other biological and abiotic factors on the abundance of H. longicornis ticks questing at each developmental stage. A total of 6223 H. longicornis adults, nymphs, and larvae were collected from 70 sites in three regions of central Japan. The abundance of questing adult and nymphal ticks was associated with deer density and other biotic and abiotic factors. However, the abundance of questing larvae showed no association with deer density but did show an association with other biotic and abiotic factors. These findings show that a high density of deer along with other biotic and abiotic factors is associated with increased risk of vector-borne diseases through amplified local abundance of questing nymphal and adult H. longicornis. Further, questing larvae abundance is likely regulated by environmental conditions and is likely correlated with survival potential or the distribution of other host species.

An Optimal Bahadur-Efficient Method in Detection of Sparse Signals with Applications to Pathway Analysis in Sequencing Association Studies.

PubMed

Dai, Hongying; Wu, Guodong; Wu, Michael; Zhi, Degui

2016-01-01

Next-generation sequencing data pose a severe curse of dimensionality, complicating traditional "single marker-single trait" analysis. We propose a two-stage combined p-value method for pathway analysis. The first stage is at the gene level, where we integrate effects within a gene using the Sequence Kernel Association Test (SKAT). The second stage is at the pathway level, where we perform a correlated Lancaster procedure to detect joint effects from multiple genes within a pathway. We show that the Lancaster procedure is optimal in Bahadur efficiency among all combined p-value methods. The Bahadur efficiency,[Formula: see text], compares sample sizes among different statistical tests when signals become sparse in sequencing data, i.e. ε →0. The optimal Bahadur efficiency ensures that the Lancaster procedure asymptotically requires a minimal sample size to detect sparse signals ([Formula: see text]). The Lancaster procedure can also be applied to meta-analysis. Extensive empirical assessments of exome sequencing data show that the proposed method outperforms Gene Set Enrichment Analysis (GSEA). We applied the competitive Lancaster procedure to meta-analysis data generated by the Global Lipids Genetics Consortium to identify pathways significantly associated with high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and total cholesterol.

Navier-Stokes Entropy Controlled Combustion Instability Analysis for Liquid Propellants

NASA Technical Reports Server (NTRS)

Chung, T. J.; Yoon, W. S.

1990-01-01

Navier-Stokes solutions are used to calculate oscillatory components of pressure, velocity, and density, which in turn provide necessary data to compute energy growth factors to determine combustion instability. It is shown that wave instabilities are associated with changes in entropy and the space and time averages of oscillatory components of pressure, velocity and density, together with the mean flow field in the energy equation. Compressible laminar and turbulent flows and reacting flows with hydrogen/oxygen combustion are considered. The SSME combustion/thrust chamber is used for illustration of the theory. The analysis shows that the increase of mean pressure and disturbances consistently results in the increase of instability. It is shown that adequate combustion instability analysis requires at least third order nonlinearity in energy growth or decay.

Functional relationships between wood structure and vulnerability to xylem cavitation in races of Eucalyptus globulus differing in wood density.

PubMed

Barotto, Antonio José; Monteoliva, Silvia; Gyenge, Javier; Martinez-Meier, Alejandro; Fernandez, María Elena

2018-02-01

Wood density can be considered as a measure of the internal wood structure, and it is usually used as a proxy measure of other mechanical and functional traits. Eucalyptus is one of the most important commercial forestry genera worldwide, but the relationship between wood density and vulnerability to cavitation in this genus has been little studied. The analysis is hampered by, among other things, its anatomical complexity, so it becomes necessary to address more complex techniques and analyses to elucidate the way in which the different anatomical elements are functionally integrated. In this study, vulnerability to cavitation in two races of Eucalyptus globulus Labill. with different wood density was evaluated through Path analysis, a multivariate method that allows evaluation of descriptive models of causal relationship between variables. A model relating anatomical variables with wood properties and functional parameters was proposed and tested. We found significant differences in wood basic density and vulnerability to cavitation between races. The main exogenous variables predicting vulnerability to cavitation were vessel hydraulic diameter and fibre wall fraction. Fibre wall fraction showed a direct impact on wood basic density and the slope of vulnerability curve, and an indirect and negative effect over the pressure imposing 50% of conductivity loss (P50) through them. Hydraulic diameter showed a direct negative effect on P50, but an indirect and positive influence over this variable through wood density on one hand, and through maximum hydraulic conductivity (ks max) and slope on the other. Our results highlight the complexity of the relationship between xylem efficiency and safety in species with solitary vessels such as Eucalyptus spp., with no evident compromise at the intraspecific level. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Preparation and characterization of poly(vinyl alcohol)/graphene nanofibers synthesized by electrospinning

NASA Astrophysics Data System (ADS)

Barzegar, Farshad; Bello, Abdulhakeem; Fabiane, Mopeli; Khamlich, Saleh; Momodu, Damilola; Taghizadeh, Fatemeh; Dangbegnon, Julien; Manyala, Ncholu

2015-02-01

We report on the synthesis and characterization of electrospun polyvinyl alcohol (PVA)/graphene nanofibers. The samples produced were characterized by Raman spectroscopy for structural and defect density analysis, scanning electron microscopy (SEM) for morphological analysis, and thermogravimetric (TGA) for thermal analysis. SEM measurements show uniform hollow PVA fibers formation and excellent graphene dispersion within the fibers, while TGA measurements show the improved thermal stability of PVA in the presence of graphene. The synthesized polymer reinforced nanofibers have potential to serve in many different applications such as thermal management, supercapacitor electrodes and biomedical materials for drug delivery.

Mercury and trace element distribution in density separates of a South African Highveld (#4) coal: Implications for mercury reduction and preparation of export coal

USGS Publications Warehouse

Kolker, Allan; Senior, Connie L.; van Alphen, Chris; Koenig, Alan E.; Geboy, Nicholas J.

2017-01-01

Eight density separates of Permian Highveld (#4) coal were investigated for partitioning of Hg and trace elements. The separates include float fractions obtained in heavy media having densities of 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 g/cm3, and the sink fraction for 2.0 g/cm3. Bulk analysis of the separates shows strong (R2 ≥ 0.80) positive correlations between pyritic sulfur and mercury, and between ash yield and both pyritic sulfur and mercury. Laser ablation (LA) ICP-MS analysis of individual pyrite grains in the separates confirms association of Hg and As with pyrite as indicated by bulk analysis. Other elements detected in pyrite by LA-ICP-MS include Mn, Co, Ni, Tl, and Pb. Results for the separates allow prediction of Hg, trace elements, and ash yields expected in specific South African coal products. These range from 0.06 ppm Hg and an ash yield of 11.5% ash for the export fraction to 0.47 ppm Hg and an ash yield of 60.9% for the discard (stone) fraction (dry basis). Results show pronounced differences expected between coal used for domestic power generation and coal which is exported.

Electronic structure and optical property of boron doped semiconducting graphene nanoribbons

NASA Astrophysics Data System (ADS)

Chen, Aqing; Shao, Qingyi; Wang, Li; Deng, Feng

2011-08-01

We present a system study on the electronic structure and optical property of boron doped semiconducting graphene nanoribbons using the density functional theory. Energy band structure, density of states, deformation density, Mulliken popular and optical spectra are considered to show the special electronic structure of boron doped semiconducting graphene nanoribbons. The C-B bond form is discussed in detail. From our analysis it is concluded that the Fermi energy of boron doped semiconducting graphene nanoribbons gets lower than that of intrinsic semiconducting graphene nanoribbons. Our results also show that the boron doped semiconducting graphene nanoribbons behave as p-type semiconducting and that the absorption coefficient of boron doped armchair graphene nanoribbons is generally enhanced between 2.0 eV and 3.3 eV. Therefore, our results have a great significance in developing nano-material for fabricating the nano-photovoltaic devices.

Field effect transistors based on phosphorene nanoribbon with selective edge-adsorption: A first-principles study

NASA Astrophysics Data System (ADS)

Hu, Mengli; Yang, Zhixiong; Zhou, Wenzhe; Li, Aolin; Pan, Jiangling; Ouyang, Fangping

2018-04-01

By using density functional theory (DFT) and nonequilibrium Green's function (NEGF), field effect transistor (FET) based on zigzag shaped phosphorene nanoribbons (ZPNR) are investigated. The FETs are constructed with bare-edged ZPNRs as electrodes and H, Cl or OH adsorbed ZPNRs as channel. It is found FETs with the three kinds of channel show similar transport properties. The FET is p-type with a maximum current on/off ratio of 104 and a minimum off-current of 1 nA. The working mode of FETs is dependent on the parity of channel length. It can be either enhancement mode or depletion mode and the off-state current shows an even-odd oscillation. The current oscillations are interpreted with density of states (DOS) analysis and methods of evolution operator and tight-binding Hamiltonian. Operating mechanism of the designed FETs is also presented with projected local density of states and band diagrams.

A First Look at Electric Motor Noise For Future Propulsion Systems

NASA Technical Reports Server (NTRS)

Huff, Dennis L.; Henderson, Brenda S.; Envia, Edmane

2016-01-01

Motor tone predictions using a vibration analysis and input from design parameters for high power density motors show that the noise can be significantly higher or lower than the empirical correlations and exceeds the stated uncertainty.

Influence of the first wall material on the particle fuelling in ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Lunt, T.; Reimold, F.; Wolfrum, E.; Carralero, D.; Feng, Y.; Schmid, K.; the ASDEX Upgrade Team

2017-05-01

In the period from 2002 to 2007 the material of the plasma facing components (PFCs) of ASDEX Upgrade (AUG) was changed from carbon (C) to tungsten (W). Comparing the measured density profiles of low-density L-mode discharges with little or no gas puff before and after this modification, a significantly higher pedestal-top density was found for W PFCs together with a steeper gradient and a lower pedestal temperature. This change can be explained by larger particle- and energy reflection coefficients for D on W compared to D on C, as shown by EMC3-EIRENE simulations of AUG discharges in similar conditions on a computational grid extending to the main chamber first wall. In the simulations, a change of the wall material at fixed separatrix density indeed shows that for W PFCs more neutrals cross the separatrix, resulting in a steeper density gradient. Analysis of the source resolved and poloidally resolved neutral flux densities across the separatrix show a dominant contribution of the divertor targets to the fuelling profile in the simulation of the low density case. Increasing the density decreases the electron temperature at the target and therefore the potential drop in the electrostatic sheath as well as the energy of the ions impinging on the surface. Neutrals with ∼eV energies, able to reach the separatrix, are then only produced via molecular dissociation processes in the plasma volume independently of the PFC material. Also the contribution of the main chamber PFCs to the fuelling is observed to increase at higher densities.

An investigation of density measurement method for yarn-dyed woven fabrics based on dual-side fusion technique

NASA Astrophysics Data System (ADS)

Zhang, Rui; Xin, Binjie

2016-08-01

Yarn density is always considered as the fundamental structural parameter used for the quality evaluation of woven fabrics. The conventional yarn density measurement method is based on one-side analysis. In this paper, a novel density measurement method is developed for yarn-dyed woven fabrics based on a dual-side fusion technique. Firstly, a lab-used dual-side imaging system is established to acquire both face-side and back-side images of woven fabric and the affine transform is used for the alignment and fusion of the dual-side images. Then, the color images of the woven fabrics are transferred from the RGB to the CIE-Lab color space, and the intensity information of the image extracted from the L component is used for texture fusion and analysis. Subsequently, three image fusion methods are developed and utilized to merge the dual-side images: the weighted average method, wavelet transform method and Laplacian pyramid blending method. The fusion efficacy of each method is evaluated by three evaluation indicators and the best of them is selected to do the reconstruction of the complete fabric texture. Finally, the yarn density of the fused image is measured based on the fast Fourier transform, and the yarn alignment image could be reconstructed using the inverse fast Fourier transform. Our experimental results show that the accuracy of density measurement by using the proposed method is close to 99.44% compared with the traditional method and the robustness of this new proposed method is better than that of conventional analysis methods.

Protein quantification on dendrimer-activated surfaces by using time-of-flight secondary ion mass spectrometry and principal component regression

NASA Astrophysics Data System (ADS)

Kim, Young-Pil; Hong, Mi-Young; Shon, Hyun Kyong; Chegal, Won; Cho, Hyun Mo; Moon, Dae Won; Kim, Hak-Sung; Lee, Tae Geol

2008-12-01

Interaction between streptavidin and biotin on poly(amidoamine) (PAMAM) dendrimer-activated surfaces and on self-assembled monolayers (SAMs) was quantitatively studied by using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The surface protein density was systematically varied as a function of protein concentration and independently quantified using the ellipsometry technique. Principal component analysis (PCA) and principal component regression (PCR) were used to identify a correlation between the intensities of the secondary ion peaks and the surface protein densities. From the ToF-SIMS and ellipsometry results, a good linear correlation of protein density was found. Our study shows that surface protein densities are higher on dendrimer-activated surfaces than on SAMs surfaces due to the spherical property of the dendrimer, and that these surface protein densities can be easily quantified with high sensitivity in a label-free manner by ToF-SIMS.

A new numerical benchmark of a freshwater lens

NASA Astrophysics Data System (ADS)

Stoeckl, L.; Walther, M.; Graf, T.

2016-04-01

A numerical benchmark for 2-D variable-density flow and solute transport in a freshwater lens is presented. The benchmark is based on results of laboratory experiments conducted by Stoeckl and Houben (2012) using a sand tank on the meter scale. This benchmark describes the formation and degradation of a freshwater lens over time as it can be found under real-world islands. An error analysis gave the appropriate spatial and temporal discretization of 1 mm and 8.64 s, respectively. The calibrated parameter set was obtained using the parameter estimation tool PEST. Comparing density-coupled and density-uncoupled results showed that the freshwater-saltwater interface position is strongly dependent on density differences. A benchmark that adequately represents saltwater intrusion and that includes realistic features of coastal aquifers or freshwater lenses was lacking. This new benchmark was thus developed and is demonstrated to be suitable to test variable-density groundwater models applied to saltwater intrusion investigations.

Dynamics of a Two-Dimensional System of Quantum Dipoles

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

Mazzanti, F.; Astrakharchik, G. E.; Boronat, J.

2009-03-20

A detailed microscopic analysis of the dynamic structure function S(k,{omega}) of a two-dimensional Bose system of dipoles polarized along the direction perpendicular to the plane is presented and discussed. Starting from ground-state quantities obtained using a quantum diffusion Monte Carlo algorithm, the density-density response is evaluated in the context of the correlated basis functions (CBF) theory. CBF predicts a sharp peak and a multiexcitation component at higher energies produced by the decay of excitations. We discuss the structure of the phonon-roton peak and show that the Feynman and Bogoliubov predictions depart from the CBF result already at low densities. Wemore » finally discuss the emergence of a roton in the spectrum, but find the roton energy not low enough to make the system unstable under density fluctuations up to the highest density considered that is close to the freezing point.« less

Spatio-Temporal Characteristics of Resident Trip Based on Poi and OD Data of Float CAR in Beijing

NASA Astrophysics Data System (ADS)

Mou, N.; Li, J.; Zhang, L.; Liu, W.; Xu, Y.

2017-09-01

Due to the influence of the urban inherent regional functional distribution, the daily activities of the residents presented some spatio-temporal patterns (periodic patterns, gathering patterns, etc.). In order to further understand the spatial and temporal characteristics of urban residents, this paper research takes the taxi trajectory data of Beijing as a sample data and studies the spatio-temporal characteristics of the residents' activities on the weekdays. At first, according to the characteristics of the taxi trajectory data distributed along the road network, it takes the Voronoi generated by the road nodes as the research unit. This paper proposes a hybrid clustering method - based on grid density, which is used to cluster the OD (origin and destination) data of taxi at different times. Then combining with the POI data of Beijing, this research calculated the density of the POI data in the clustering results, and analyzed the relationship between the activities of residents in different periods and the functional types of the region. The final results showed that the residents were mainly commuting on weekdays. And it found that the distribution of travel density showed a concentric circle of the characteristics, focusing on residential areas and work areas. The results of cluster analysis and POI analysis showed that the residents' travel had experienced the process of "spatial relative dispersion - spatial aggregation - spatial relative dispersion" in one day.

Effect on structure and mechanical property of tungsten irradiated by high intensity pulsed ion beam

NASA Astrophysics Data System (ADS)

Mei, Xianxiu; Zhang, Xiaonan; Liu, Xiaofei; Wang, Younian

2017-09-01

The anti-thermal radiation performance of tungsten was investigated by high intensity pulsed ion beam technology. The ion beam was mainly composed of Cn+ (70%) and H+ (30%) at an acceleration voltage of 250 kV under different energy densities for different number of pulses. GIXRD analysis showed that no obvious phase structural changes occurred on the tungsten, and microstress generated. SEM analysis exhibited that there was no apparent irradiation damage on the surface of tungsten at the low irradiation frequency (3 times and 10 times) and at the low energy density (0.25 J/cm2 and 0.7 J/cm2). Cracks appeared on the surface of tungsten after 100-time and 300-time irradiation. Shedding phenomenon even appeared on the surface of tungsten at the energy densities of 1.4 J/cm2 and 2.0 J/cm2. The surface nano-hardness of tungsten decreased with the increase of the pulse times and the energy density. The tungsten has good anti-thermal radiation properties under certain heat load environment.

Potential Analysis of Rainfall-induced Sediment Disaster

NASA Astrophysics Data System (ADS)

Chen, Jing-Wen; Chen, Yie-Ruey; Hsieh, Shun-Chieh; Tsai, Kuang-Jung; Chue, Yung-Sheng

2014-05-01

Most of the mountain regions in Taiwan are sedimentary and metamorphic rocks which are fragile and highly weathered. Severe erosion occurs due to intensive rainfall and rapid flow, the erosion is even worsen by frequent earthquakes and severely affects the stability of hillsides. Rivers are short and steep in Taiwan with large runoff differences in wet and dry seasons. Discharges respond rapidly with rainfall intensity and flood flows usually carry large amount of sediment. Because of the highly growth in economics and social change, the development in the slope land is inevitable in Taiwan. However, sediment disasters occur frequently in high and precipitous region during typhoon. To make the execution of the regulation of slope land development more efficiency, construction of evaluation model for sediment potential is very important. In this study, the Genetic Adaptive Neural Network (GANN) was implemented in texture analysis techniques for the classification of satellite images of research region before and after typhoon or extreme rainfall and to obtain surface information and hazard log data. By using GANN weight analysis, factors, levels and probabilities of disaster of the research areas are presented. Then, through geographic information system the disaster potential map is plotted to distinguish high potential regions from low potential regions. Finally, the evaluation processes for sediment disaster after rainfall due to slope land use are established. In this research, the automatic image classification and evaluation modules for sediment disaster after rainfall due to slope land disturbance and natural environment are established in MATLAB to avoid complexity and time of computation. After implementation of texture analysis techniques, the results show that the values of overall accuracy and coefficient of agreement of the time-saving image classification for different time periods are at intermediate-high level and above. The results of GANN show that the weight of building density is the largest in all slope land disturbance factors, followed by road density, orchard density, baren land density, vegetation density, and farmland density. The weight of geology is the largest in all natural environment factors, followed by slope roughness, slope, and elevation. Overlaying the locations of large sediment disaster in the past on the potential map predicted by GANN, we found that most damage areas were in the region with medium-high or high potential of landslide. Therefore, the proposed potential model of sediment disaster can be used in practice.

Effects of habitat characteristics on the growth of carrier population leading to increased spread of typhoid fever: a model.

PubMed

Shukla, J B; Goyal, Ashish; Singh, Shikha; Chandra, Peeyush

2014-06-01

In this paper, a non-linear model is proposed and analyzed to study the effects of habitat characteristics favoring logistically growing carrier population leading to increased spread of typhoid fever. It is assumed that the cumulative density of habitat characteristics and the density of carrier population are governed by logistic models; the growth rate of the former increases as the density of human population increases. The model is analyzed by stability theory of differential equations and computer simulation. The analysis shows that as the density of the infective carrier population increases due to habitat characteristics, the spread of typhoid fever increases in comparison with the case without such factors. Copyright © 2013 Ministry of Health, Saudi Arabia. Published by Elsevier Ltd. All rights reserved.

Frequency spectrum analysis of laser generated ultrasonic waves in ablative regime

NASA Astrophysics Data System (ADS)

Mi, Bao; Ume, I. Charles

2002-05-01

In this paper, laser ultrasonic signals generated in ablative regime are measured in a number of metal samples (2024 Al, 6061 Al, 7075 Al, mild steel, and copper) with a broadband laser interferometer. The frequency spectra are analyzed and compared for different thicknesses (50.8 mm, 25.4 mm, 12.7 mm, and 6.4 mm), and for different power densities. Hanning windowing is applied before frequency analysis is performed. The experimental data match the theoretical predictions very well. The results show that the frequency spectrum extends from 0 to 15 MHz, while the center frequency occurs near 2 MHz. The detailed distribution of the spectrum is dependent on the material, thickness, and laser power density.

Multifractal analysis with the probability density function at the three-dimensional anderson transition.

PubMed

Rodriguez, Alberto; Vasquez, Louella J; Römer, Rudolf A

2009-03-13

The probability density function (PDF) for critical wave function amplitudes is studied in the three-dimensional Anderson model. We present a formal expression between the PDF and the multifractal spectrum f(alpha) in which the role of finite-size corrections is properly analyzed. We show the non-Gaussian nature and the existence of a symmetry relation in the PDF. From the PDF, we extract information about f(alpha) at criticality such as the presence of negative fractal dimensions and the possible existence of termination points. A PDF-based multifractal analysis is shown to be a valid alternative to the standard approach based on the scaling of inverse participation ratios.

Mixing-model Sensitivity to Initial Conditions in Hydrodynamic Predictions

NASA Astrophysics Data System (ADS)

Bigelow, Josiah; Silva, Humberto; Truman, C. Randall; Vorobieff, Peter

2017-11-01

Amagat and Dalton mixing-models were studied to compare their thermodynamic prediction of shock states. Numerical simulations with the Sandia National Laboratories shock hydrodynamic code CTH modeled University of New Mexico (UNM) shock tube laboratory experiments shocking a 1:1 molar mixture of helium (He) and sulfur hexafluoride (SF6) . Five input parameters were varied for sensitivity analysis: driver section pressure, driver section density, test section pressure, test section density, and mixture ratio (mole fraction). We show via incremental Latin hypercube sampling (LHS) analysis that significant differences exist between Amagat and Dalton mixing-model predictions. The differences observed in predicted shock speeds, temperatures, and pressures grow more pronounced with higher shock speeds. Supported by NNSA Grant DE-0002913.

Higher Numbers of T-Bet+ Tumor-Infiltrating Lymphocytes Associate with Better Survival in Human Epithelial Ovarian Cancer.

PubMed

Xu, Yun; Chen, Lujun; Xu, Bin; Xiong, Yuqi; Yang, Min; Rui, Xiaohui; Shi, Liangrong; Wu, Changping; Jiang, Jingting; Lu, Binfeng

2017-01-01

T-bet, a member of the T-box family of transcription factors, is a key marker of type I immune response within the tumor microenvironment, and has been previously reported by us to serve as an important prognostic indicator for human gastric cancer patients and a potential biomarker for immunotherapy. In the present study, we aimed to assess the clinical significance and prognostic value of T-bet+ tumor-infiltrating lymphocytes in human epithelial ovarian cancer. The immunohistochemistry was used to analyze the infiltration density of T-bet+ lymphoid cells in human epithelial ovarian cancer tissues, and the flow cytometry analysis was used to further analyze the presence of T-bet+ tumor-infiltrating lymphocytes subgroups in cancer tissues. Our immunohistochemistry analysis showed increased number of T-bet+ lymphoid cells in the human epithelial ovarian cancer tissues, and the flow cytometry analysis further demonstrated the presence of T-bet+ tumor-infiltrating lymphocytes subgroups including CD4+ , CD8+ T cells and NK cells. In addition, we also observed a significant association of T-bet+ tumor-infiltrating lymphocytes density in the tumor nest of cancer with not only serum CA125 levels but also with distant metastasis. However no association was observed with other characteristics like patients' age, pathological type, FIGO stage, tumor site and tumor size. Furthermore, the survival analysis showed that higher density of T-bet+ tumor-infiltrating lymphocytes both in tumor nest and tumor stroma of cancer tissues was significantly associated with better patient survival. In addition, the density of T-bet+ tumor-infiltrating lymphocytes in tumor nest appeared to be an independent risk factor for predicting patients' postoperative prognoses. Our data indicated that the key transcription factor T-bet might play an important role in the type I immune cells mediated antitumor response, and the density of T-bet+ lymphocytes in human epithelial ovarian cancer tissues could serve as a prognostic predictor for ovarian cancer patients. © 2017 The Author(s)Published by S. Karger AG, Basel.

Detecting the environmental impact of off-road vehicles on Rawdat Al Shams in central Saudi Arabia by remote sensing.

PubMed

Dewidar, K; Thomas, J; Bayoumi, S

2016-07-01

Off-road vehicles can have a devastating impact on vegetation and soil. Here, we sought to quantify, through a combination of field vegetation, bulk soil, and image analyses, the impact of off-road vehicles on the vegetation and soils of Rawdat Al Shams, which is located in central Saudi Arabia. Soil compaction density was measured in the field, and 27 soil samples were collected for bulk density analysis in the lab to quantify the impacts of off-road vehicles. High spatial resolution images, such as those obtained by the satellites GeoEye-1 and IKONOS-2, were used for surveying the damage to vegetation cover and soil compaction caused by these vehicles. Vegetation cover was mapped using the Normalized Difference Vegetation Index (NDVI) technique based on high-resolution images taken at different times of the year. Vehicle trails were derived from satellite data via visual analysis. All damaged areas were determined from high-resolution image data. In this study, we conducted quantitative analyses of vegetation cover change, the impacts of vehicle trails (hereafter "trail impacts"), and a bulk soil analysis. Image data showed that both vegetation cover and trail impacts increased from 2008 to 2015, with the average percentage of trail impacts nearly equal to that of the percentage of vegetation cover during this period. Forty-six species of plants were found to be present in the study area, consisting of all types of life forms, yet trees were represented by a single species, Acacia gerrardii. Herbs composed the largest share of plant life, with 29 species, followed by perennial herbs (12 species), grasses (5 species), and shrubs (3 species). Analysis of soil bulk density for Rawdat Al Shams showed that off-road driving greatly impacts soil density. Twenty-two plant species were observed on the trails, the majority of which were ephemerals. Notoceras bicorne was the most common, with a frequency rate of 93.33 %, an abundance value of 78.47 %, and a density of 0.1 in transect 1, followed by Plantago ovata.

Geospatial Characterization of Fluvial Wood Arrangement in a Semi-confined Alluvial River

NASA Astrophysics Data System (ADS)

Martin, D. J.; Harden, C. P.; Pavlowsky, R. T.

2014-12-01

Large woody debris (LWD) has become universally recognized as an integral component of fluvial systems, and as a result, has become increasingly common as a river restoration tool. However, "natural" processes of wood recruitment and the subsequent arrangement of LWD within the river network are poorly understood. This research used a suite of spatial statistics to investigate longitudinal arrangement patterns of LWD in a low-gradient, Midwestern river. First, a large-scale GPS inventory of LWD, performed on the Big River in the eastern Missouri Ozarks, resulted in over 4,000 logged positions of LWD along seven river segments that covered nearly 100 km of the 237 km river system. A global Moran's I analysis indicates that LWD density is spatially autocorrelated and displays a clustering tendency within all seven river segments (P-value range = 0.000 to 0.054). A local Moran's I analysis identified specific locations along the segments where clustering occurs and revealed that, on average, clusters of LWD density (high or low) spanned 400 m. Spectral analyses revealed that, in some segments, LWD density is spatially periodic. Two segments displayed strong periodicity, while the remaining segments displayed varying degrees of noisiness. Periodicity showed a positive association with gravel bar spacing and meander wavelength, although there were insufficient data to statistically confirm the relationship. A wavelet analysis was then performed to investigate periodicity relative to location along the segment. The wavelet analysis identified significant (α = 0.05) periodicity at discrete locations along each of the segments. Those reaches yielding strong periodicity showed stronger relationships between LWD density and the geomorphic/riparian independent variables tested. Analyses consistently identified valley width and sinuosity as being associated with LWD density. The results of these analyses contribute a new perspective on the longitudinal distribution of LWD in a river system, which should help identify physical and/or riparian control mechanisms of LWD arrangement and support the development of models of LWD arrangement. Additionally, the spatial statistical tools presented here have shown to be valuable for identifying longitudinal patterns in river system components.

Development of indirect EFBEM for radiating noise analysis including underwater problems

NASA Astrophysics Data System (ADS)

Kwon, Hyun-Wung; Hong, Suk-Yoon; Song, Jee-Hun

2013-09-01

For the analysis of radiating noise problems in medium-to-high frequency ranges, the Energy Flow Boundary Element Method (EFBEM) was developed. EFBEM is the analysis technique that applies the Boundary Element Method (BEM) to Energy Flow Analysis (EFA). The fundamental solutions representing spherical wave property for radiating noise problems in open field and considering the free surface effect in underwater are developed. Also the directivity factor is developed to express wave's directivity patterns in medium-to-high frequency ranges. Indirect EFBEM by using fundamental solutions and fictitious source was applied to open field and underwater noise problems successfully. Through numerical applications, the acoustic energy density distributions due to vibration of a simple plate model and a sphere model were compared with those of commercial code, and the comparison showed good agreement in the level and pattern of the energy density distributions.

Quantum chemical calculation (electronic and topologic) and experimental (FT-IR, FT-Raman and UV) analysis of isonicotinic acid N-oxide

NASA Astrophysics Data System (ADS)

Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

2015-04-01

In this work, the molecular conformation, vibrational and electronic analysis of isonicotinic acid N-oxide (iso-NANO) were presented in the ground state using experimental techniques (FT-IR, FT-Raman and UV) and density functional theory (DFT) employing B3LYP exchange correlation with the 6-311++G(d,p) basis set. The geometry optimization and energies associated possible two conformers (Rot-I and Rot-II) were computed. The vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The obtained structures were analyzed with the Atoms in Molecules (AIMs) methodology. The computational results diagnose the most stable conformer of iso-NANO as the Rot-I form. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (OPDOS) diagrams analysis for the most stable conformer (Rot-I) were calculated using the same method. Thermodynamic properties (heat capacity, entropy and enthalpy) of the title compound at different temperatures were calculated. As a result, the optimized geometry and calculated spectroscopic data show a good agreement with the experimental results.

CT analysis of lung density changes in patients undergoing total body irradiation prior to bone marrow transplantation.

PubMed

Lee, J Y; Shank, B; Bonfiglio, P; Reid, A

1984-10-01

Sequential changes in lung density measured by CT are potentially sensitive and convenient monitors of lung abnormalities following total body irradiation (TBI). Methods have been developed to compare pre- and post-TBI CT of lung. The average local features of a cross-sectional lung slice are extracted from three peripheral regions of interest in the anterior, posterior, and lateral portions of the CT image. Also, density profiles across a specific region may be obtained. These may be compared first for verification of patient position and breathing status and then for changes between pre- and post-TBI. These may also be compared with radiation dose profiles through the lung. A preliminary study on 21 leukemia patients undergoing total body irradiation indicates the following: (a) Density gradients of patients' lungs in the antero-posterior direction show a marked heterogeneity before and after transplantation compared with normal lungs. The patients with departures from normal density gradients pre-TBI correlate with later pulmonary complications. (b) Measurements of average peripheral lung densities have demonstrated that the average lung density in the younger age group is substantially higher: pre-TBI, the average CT number (1,000 scale) is -638 +/- 39 Hounsfield unit (HU) for 0-10 years old and -739 +/- 53 HU for 21-40 years old. (c) Density profiles showed no post-TBI regional changes in lung density corresponding to the dose profile across the lung, so no differentiation of a radiation-specific effect has yet been possible. Computed tomographic density profiles in the antero-posterior direction are successfully used to verify positioning of the CT slice and the breathing level of the lung.

Evaluation of an analytic linear Boltzmann transport equation solver for high-density inhomogeneities

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

Lloyd, S. A. M.; Ansbacher, W.; Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 3P6

2013-01-15

Purpose: Acuros external beam (Acuros XB) is a novel dose calculation algorithm implemented through the ECLIPSE treatment planning system. The algorithm finds a deterministic solution to the linear Boltzmann transport equation, the same equation commonly solved stochastically by Monte Carlo methods. This work is an evaluation of Acuros XB, by comparison with Monte Carlo, for dose calculation applications involving high-density materials. Existing non-Monte Carlo clinical dose calculation algorithms, such as the analytic anisotropic algorithm (AAA), do not accurately model dose perturbations due to increased electron scatter within high-density volumes. Methods: Acuros XB, AAA, and EGSnrc based Monte Carlo are usedmore » to calculate dose distributions from 18 MV and 6 MV photon beams delivered to a cubic water phantom containing a rectangular high density (4.0-8.0 g/cm{sup 3}) volume at its center. The algorithms are also used to recalculate a clinical prostate treatment plan involving a unilateral hip prosthesis, originally evaluated using AAA. These results are compared graphically and numerically using gamma-index analysis. Radio-chromic film measurements are presented to augment Monte Carlo and Acuros XB dose perturbation data. Results: Using a 2% and 1 mm gamma-analysis, between 91.3% and 96.8% of Acuros XB dose voxels containing greater than 50% the normalized dose were in agreement with Monte Carlo data for virtual phantoms involving 18 MV and 6 MV photons, stainless steel and titanium alloy implants and for on-axis and oblique field delivery. A similar gamma-analysis of AAA against Monte Carlo data showed between 80.8% and 87.3% agreement. Comparing Acuros XB and AAA evaluations of a clinical prostate patient plan involving a unilateral hip prosthesis, Acuros XB showed good overall agreement with Monte Carlo while AAA underestimated dose on the upstream medial surface of the prosthesis due to electron scatter from the high-density material. Film measurements support the dose perturbations demonstrated by Monte Carlo and Acuros XB data. Conclusions: Acuros XB is shown to perform as well as Monte Carlo methods and better than existing clinical algorithms for dose calculations involving high-density volumes.« less

Investigation of reliability of the cutoff probe by a comparison with Thomson scattering in high density processing plasmas

NASA Astrophysics Data System (ADS)

Seo, Byonghoon; Kim, Dae-Woong; Kim, Jung-Hyung; You, Shinjae

2017-12-01

A "cutoff probe" uses microwaves to measure the electron density in a plasma. It is particularly attractive because it is easy to fabricate and use, its measurement is immune to surface contamination by dielectric materials, and it has a straightforward analysis to measure electron density in real time. In this work, we experimentally investigate the accuracy of the cutoff probe through a detailed comparison with Thomson scattering in a low temperature, high density processing plasma. The result shows that the electron density measured by the cutoff probe is lower than that by Thomson scattering and that the discrepancy of the two results becomes smaller as the gap between the two tips increases and/or the neutral gas pressure decreases. The underestimated electron density found by the cutoff probe can be explained by the influence of the probe holder, which becomes important as the pressure increases and the gap gets closer.

Statistical results from 10 years of Cassini Langmuir probe plasma measurements

NASA Astrophysics Data System (ADS)

Holmberg, M.; Shebanits, O.; Wahlund, J. E.; Morooka, M.; Andre, N.

2016-12-01

We use a new analysis method to obtain 10 years of Cassini RPWS Langmuir probe (LP) measurements to study the structure and dynamics of the inner plasma disk of Saturn. The LP plasma density measurements show good agreement with electron densities derived from the RPWS electric field power spectra and confirms and/or improves a number of previous findings about the structure of the plasma disk. E.g., the Enceladus plume is detected as a localised density maximum at the orbit of Enceladus, but the peak density of the inner plasma disk, excluding Enceladus plume passages, is located closer to 4.7 Rs. No density peaks are recorded at the orbits of the moons Mimas, Tethys, Dione, and Rhea. We confirm the previously detected plasma density dayside/nightside asymmetry, which is likely due to a particle drift in the dusk to dawn direction. Presented is also the LP result on the seasonal dependence of the plasma disk within Enceladus' orbit.

Variants for HDL-C, LDL-C and Triglycerides Identified from Admixture Mapping and Fine-Mapping Analysis in African-American Families

PubMed Central

Shetty, Priya B.; Tang, Hua; Feng, Tao; Tayo, Bamidele; Morrison, Alanna C.; Kardia, Sharon L.R.; Hanis, Craig L.; Arnett, Donna K.; Hunt, Steven C.; Boerwinkle, Eric; Rao, D.C.; Cooper, R.S.; Risch, Neil; Zhu, Xiaofeng

2015-01-01

Background Admixture mapping of lipids was followed-up by family-based association analysis to identify variants for cardiovascular disease in African-Americans. Methods and Results The present study conducted admixture mapping analysis for total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides. The analysis was performed in 1,905 unrelated African-American subjects from the National Heart, Lung and Blood Institute’s Family Blood Pressure Program. Regions showing admixture evidence were followed-up with family-based association analysis in 3,556 African-American subjects from the FBPP. The admixture mapping and family-based association analyses were adjusted for age, age2, sex, body-mass-index, and genome-wide mean ancestry to minimize the confounding due to population stratification. Regions that were suggestive of local ancestry association evidence were found on chromosomes 7 (LDL-C), 8 (HDL-C), 14 (triglycerides) and 19 (total cholesterol and triglycerides). In the fine-mapping analysis, 52,939 SNPs were tested and 11 SNPs (8 independent SNPs) showed nominal significant association with HDL-C (2 SNPs), LDL-C (4 SNPs) and triglycerides (5 SNPs). The family data was used in the fine-mapping to identify SNPs that showed novel associations with lipids and regions including genes with known associations for cardiovascular disease. Conclusions This study identified regions on chromosomes 7, 8, 14 and 19 and 11 SNPs from the fine-mapping analysis that were associated with HDL-C, LDL-C and triglycerides for further studies of cardiovascular disease in African-Americans. PMID:25552592

Application of continuous normal-lognormal bivariate density functions in a sensitivity analysis of municipal solid waste landfill.

PubMed

Petrovic, Igor; Hip, Ivan; Fredlund, Murray D

2016-09-01

The variability of untreated municipal solid waste (MSW) shear strength parameters, namely cohesion and shear friction angle, with respect to waste stability problems, is of primary concern due to the strong heterogeneity of MSW. A large number of municipal solid waste (MSW) shear strength parameters (friction angle and cohesion) were collected from published literature and analyzed. The basic statistical analysis has shown that the central tendency of both shear strength parameters fits reasonably well within the ranges of recommended values proposed by different authors. In addition, it was established that the correlation between shear friction angle and cohesion is not strong but it still remained significant. Through use of a distribution fitting method it was found that the shear friction angle could be adjusted to a normal probability density function while cohesion follows the log-normal density function. The continuous normal-lognormal bivariate density function was therefore selected as an adequate model to ascertain rational boundary values ("confidence interval") for MSW shear strength parameters. It was concluded that a curve with a 70% confidence level generates a "confidence interval" within the reasonable limits. With respect to the decomposition stage of the waste material, three different ranges of appropriate shear strength parameters were indicated. Defined parameters were then used as input parameters for an Alternative Point Estimated Method (APEM) stability analysis on a real case scenario of the Jakusevec landfill. The Jakusevec landfill is the disposal site of the capital of Croatia - Zagreb. The analysis shows that in the case of a dry landfill the most significant factor influencing the safety factor was the shear friction angle of old, decomposed waste material, while in the case of a landfill with significant leachate level the most significant factor influencing the safety factor was the cohesion of old, decomposed waste material. The analysis also showed that a satisfactory level of performance with a small probability of failure was produced for the standard practice design of waste landfills as well as an analysis scenario immediately after the landfill closure. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characterization and processing of heat treated aluminium matrix composite

NASA Astrophysics Data System (ADS)

Doifode, Yogesh; Kulkarni, S. G.

2018-05-01

The present study is carried out to determine density and porosity of Aluminium bagasse ash reinforced composite produced by powder metallurgy method. Bagasse ash is used as reinforcement material having high silica and alumina contents and varied from 5 weight % to 40 weight%. The manufactured composite is heat treated, the main objective of heat treatment is to prepare the material structurally and physically fit for engineering application. The results showed that the density decreases with percentage increase in reinforcement of bagasse ash from 2.6618 gm/cm3 to 1.9830 gm/cm3 with the minimum value at 40 weight% bagasse ash without heat treatment whereas after heat treatment density of composite increases due filling up of voids and porous holes. Heat treatment processing is the key to this improvement, with the T6 heat treated composite to convene the reduced porosity of composite. Consequently aluminium metal matrix composite combines the strength of the reinforcement to achieve a combination of desirable properties not available in any single material. It may observe that porosity in case of powder metallurgy samples showed more porosity portions compare to the casting samples. In order to achieve optimality in structure and properties of Bagasse ash-reinforcement heat treatment techniques have evolved. Generally, the ceramic reinforcements increase the density of the base alloy during fabrication of composites. However, the addition of lightweight reinforcements reduces the density of the hybrid composites. The results also showed that, the density varies from to with minimum value at 40 wt. % BA. The results of the statistical analysis showed that there are significant differences among the means of each property of the composites at various levels of BA replacement .It was concluded that bagasse ash can be used as reinforcement and the produced composites have low density and heat treatment reduces porosity which could be used in automobile industry for the production of engine parts.

AzTEC Survey of the Central Molecular Zone: Modeling Dust SEDs and N-PDF with Hierarchical Bayesian Analysis

NASA Astrophysics Data System (ADS)

Tang, Yuping; Wang, Daniel; Wilson, Grant; Gutermuth, Robert; Heyer, Mark

2018-01-01

We present the AzTEC/LMT survey of dust continuum at 1.1mm on the central ˜ 200pc (CMZ) of our Galaxy. A joint SED analysis of all existing dust continuum surveys on the CMZ is performed, from 160µm to 1.1mm. Our analysis follows a MCMC sampling strategy incorporating the knowledge of PSFs in different maps, which provides unprecedented spacial resolution on distributions of dust temperature, column density and emissivity index. The dense clumps in the CMZ typically show low dust temperature ( 20K), with no significant sign of buried star formation, and a weak evolution of higher emissivity index toward dense peak. A new model is proposed, allowing for varying dust temperature inside a cloud and self-shielding of dust emission, which leads to similar conclusions on dust temperature and grain properties. We further apply a hierarchical Bayesian analysis to infer the column density probability distribution function (N-PDF), while simultaneously removing the Galactic foreground and background emission. The N-PDF shows a steep power-law profile with α > 3, indicating that formation of dense structures are suppressed.

Molecular orbital studies (hardness, chemical potential, electronegativity and electrophilicity), vibrational spectroscopic investigation and normal coordinate analysis of 5-{1-hydroxy-2-[(propan-2-yl)amino]ethyl}benzene-1,3-diol.

PubMed

Muthu, S; Renuga, S

2014-01-24

FT-IR and FT-Raman spectra of 5-{1-hydroxy-2-[(propan-2-yl) amino] ethyl} benzene-1,3-diol (abbrevi- 54 ated as HPAEBD) were recorded in the region 4000-450 cm(-1) and 4000-100 cm(-1) respectively. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (B3LYP) and HF method with 6-31 G(d,p) as basis set. The theoretical wave numbers were scaled and compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated Potential energy distribution (PED). Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the σ antibonding orbitals and E (2) energies confirm the occurrence of intra molecular charge transfer (ICT) within the molecule. The molecule orbital contributions were studied by using the total (TDOS), sum of α and β electron (αβDOS) density of States. Mulliken population analysis of atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in this compound. On the basis of vibrational analyses, the thermodynamic properties of title compound at different temperatures have been calculated. Copyright © 2013 Elsevier B.V. All rights reserved.

Constructing the AdS dual of a Fermi liquid: AdS black holes with Dirac hair

NASA Astrophysics Data System (ADS)

Čubrović, Mihailo; Zaanen, Jan; Schalm, Koenraad

2011-10-01

We provide evidence that the holographic dual to a strongly coupled charged Fermi liquid has a non-zero fermion density in the bulk. We show that the pole-strength of the stable quasiparticle characterizing the Fermi surface is encoded in the AdS probability density of a single normalizable fermion wavefunction in AdS. Recalling Migdal's theorem which relates the pole strength to the Fermi-Dirac characteristic discontinuity in the number density at ω F , we conclude that the AdS dual of a Fermi liquid is described by occupied on-shell fermionic modes in AdS. Encoding the occupied levels in the total spatially averaged probability density of the fermion field directly, we show that an AdS Reissner-Nordström black holein a theory with charged fermions has a critical temperature, at which the system undergoes a first-order transition to a black hole with a non-vanishing profile for the bulk fermion field. Thermodynamics and spectral analysis support that the solution with non-zero AdS fermion-profile is the preferred ground state at low temperatures.

Molecular column densities in selected model atmospheres. [chemical analysis of carbon stars

NASA Technical Reports Server (NTRS)

Johnson, H. R.; Beebe, R. F.; Sneden, C.

1974-01-01

From an examination of predicted column densities, the following conclusions were drawn: (1) The SiO ought to be visible in carbon stars which were generated from triple alpha burning, but absent from carbon stars generated from the CNO bi-cycle. (2) Variation in the observed relative strengths of TiO and ZrO is indicative of real differences in the ratio Ti/Zr. (3) The TiO/ZrO ratio shows a small variation as C/O and effective temperature is changed. (4) Column density of silicon dicarbide (SiC2) is sensitive to abundance, temperature, and gravity; hence all relationships between the strength of SiC2 and other stellar parameters will show appreciable scatter. There is however, a substantial luminosity effect present in the SiC2 column densities. (5) Unexpectedly, SiC2 is anti-correlated with C2. (6) The presence of SiC2 in a carbon star eliminates the possibility of these stars having temperatures greater than or equal to 3000 K, or being produced through the CNO bi-cycle.

Generation of multiple toroidal dust vortices by a non-monotonic density gradient in a direct current glow discharge plasma

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

Kaur, Manjit, E-mail: manjit@ipr.res.in; Bose, Sayak; Chattopadhyay, P. K.

2015-09-15

Observation of two well-separated dust vortices in an unmagnetized parallel plate DC glow discharge plasma is reported in this paper. A non-monotonic radial density profile, achieved by an especially designed cathode structure using a concentric metallic disk and ring of different radii, is observed to produce double dust tori between cathode and anode. PIV analysis of the still images of the double tori shows oppositely rotating dust structures between the central disk and the ring. Langmuir probe measurements of background plasma shows a non-uniform plasma density profile between the disk and the ring. Location and sense of rotation of themore » dust vortices coincides with the location and direction of the radial gradient in the ion drag force caused by the radial density gradient. The experimentally observed dust vorticity matches well with the calculated one using hydrodynamic formulations with shear in ion drag dominating over the dust charge gradient. These results corroborate that a radial gradient in the ion drag force directed towards cathode is the principal cause of dust rotation.« less

Contact angle adjustment in equation-of-state-based pseudopotential model.

PubMed

Hu, Anjie; Li, Longjian; Uddin, Rizwan; Liu, Dong

2016-05-01

The single component pseudopotential lattice Boltzmann model has been widely applied in multiphase simulation due to its simplicity and stability. In many studies, it has been claimed that this model can be stable for density ratios larger than 1000. However, the application of the model is still limited to small density ratios when the contact angle is considered. The reason is that the original contact angle adjustment method influences the stability of the model. Moreover, simulation results in the present work show that, by applying the original contact angle adjustment method, the density distribution near the wall is artificially changed, and the contact angle is dependent on the surface tension. Hence, it is very inconvenient to apply this method with a fixed contact angle, and the accuracy of the model cannot be guaranteed. To solve these problems, a contact angle adjustment method based on the geometry analysis is proposed and numerically compared with the original method. Simulation results show that, with our contact angle adjustment method, the stability of the model is highly improved when the density ratio is relatively large, and it is independent of the surface tension.

Contact angle adjustment in equation-of-state-based pseudopotential model

NASA Astrophysics Data System (ADS)

Hu, Anjie; Li, Longjian; Uddin, Rizwan; Liu, Dong

2016-05-01

The single component pseudopotential lattice Boltzmann model has been widely applied in multiphase simulation due to its simplicity and stability. In many studies, it has been claimed that this model can be stable for density ratios larger than 1000. However, the application of the model is still limited to small density ratios when the contact angle is considered. The reason is that the original contact angle adjustment method influences the stability of the model. Moreover, simulation results in the present work show that, by applying the original contact angle adjustment method, the density distribution near the wall is artificially changed, and the contact angle is dependent on the surface tension. Hence, it is very inconvenient to apply this method with a fixed contact angle, and the accuracy of the model cannot be guaranteed. To solve these problems, a contact angle adjustment method based on the geometry analysis is proposed and numerically compared with the original method. Simulation results show that, with our contact angle adjustment method, the stability of the model is highly improved when the density ratio is relatively large, and it is independent of the surface tension.

A deeper look at the GD1 stream: density variations and wiggles

NASA Astrophysics Data System (ADS)

de Boer, T. J. L.; Belokurov, V.; Koposov, S. E.; Ferrarese, L.; Erkal, D.; Côté, P.; Navarro, J. F.

2018-06-01

Using deep photometric data from Canada-France-Hawaii Telescope/Megacam, we study the morphology and density of the GD-1 stream, one of the longest and coldest stellar streams in the Milky Way. Our deep data recovers the lower main sequence of the stream with unprecedented quality, clearly separating it from Milky Way foreground and background stars. An analysis of the distance to different parts of the stream shows that GD-1 lies at a heliocentric distance between 8 and 10 kpc, with only a shallow gradient across 45° on the sky. Matched filter maps of the stream density show clear density variations, such as deviations from a single orbital track and tentative evidence for stream fanning. We also detect a clear underdensity in the middle of the stream track at φ1 = -45° surrounded by overdense stream segments on either side. This location is a promising candidate for the elusive missing progenitor of the GD-1 stream. We conclude that the GD-1 stream has clearly been disturbed by interactions with the Milky Way disc or other subhaloes.

Cluster and constraint analysis in tetrahedron packings

NASA Astrophysics Data System (ADS)

Jin, Weiwei; Lu, Peng; Liu, Lufeng; Li, Shuixiang

2015-04-01

The disordered packings of tetrahedra often show no obvious macroscopic orientational or positional order for a wide range of packing densities, and it has been found that the local order in particle clusters is the main order form of tetrahedron packings. Therefore, a cluster analysis is carried out to investigate the local structures and properties of tetrahedron packings in this work. We obtain a cluster distribution of differently sized clusters, and peaks are observed at two special clusters, i.e., dimer and wagon wheel. We then calculate the amounts of dimers and wagon wheels, which are observed to have linear or approximate linear correlations with packing density. Following our previous work, the amount of particles participating in dimers is used as an order metric to evaluate the order degree of the hierarchical packing structure of tetrahedra, and an order map is consequently depicted. Furthermore, a constraint analysis is performed to determine the isostatic or hyperstatic region in the order map. We employ a Monte Carlo algorithm to test jamming and then suggest a new maximally random jammed packing of hard tetrahedra from the order map with a packing density of 0.6337.

Elastic Heterogeneity in Metallic Glasses

NASA Astrophysics Data System (ADS)

Dmowski, W.; Iwashita, T.; Chuang, C.-P.; Almer, J.; Egami, T.

2010-11-01

When a stress is applied on a metallic glass it deforms following Hook’s law. Therefore it may appear obvious that a metallic glass deforms elastically. Using x-ray diffraction and anisotropic pair-density function analysis we show that only about (3)/(4) in volume fraction of metallic glasses deforms elastically, whereas the rest of the volume is anelastic and in the experimental time scale deform without resistance. We suggest that this anelastic portion represents residual liquidity in the glassy state. Many theories, such as the free-volume theory, assume the density of defects in the glassy state to be of the order of 1%, but this result shows that it is as much as a quarter.

Studies on densification, mechanical, micro-structural and structure–properties relationship of magnesium aluminate spinel refractory aggregates prepared from Indian magnesite

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

Ghosh, Chandrima; Ghosh, Arup; Haldar, Manas Kamal, E-mail: manashaldar@cgcri.res.in

The present work intends to study the development of magnesium aluminate spinel aggregates from Indian magnesite in a single firing stage. The raw magnesite has been evaluated in terms of chemical analysis, differential thermal analysis, thermogravimetric analysis, infrared spectroscopy, and X-ray diffraction. The experimental batch containing Indian magnesite and calcined alumina has been sintered in the temperature range of 1550 °C–1700 °C. The sintered material has been characterized in terms of physico-chemical properties like bulk density, apparent porosity, true density, relative density and thermo-mechanical/mechanical properties like hot modulus of rupture, thermal shock resistance, cold modulus of rupture and structural propertiesmore » by X-ray diffraction in terms of phase identification and evaluation of crystal structure parameters of corresponding phases by Rietveld analysis. The microstructures developed at different temperatures have been analyzed by field emission scanning electron microscope study and compositional analysis of the developed phase has been carried out by energy dispersive X-ray study. - Highlights: • The studies have been done to characterize the developed magnesium aluminate spinel. • The studies reveal correlation between refractory behavior of spinel and developed microstructures. • The studies show the values of lattice parameters of developed phases.« less

Non-high-density lipoprotein cholesterol: an important predictor of stroke and diabetes-related mortality in Japanese elderly diabetic patients.

PubMed

Araki, Atsushi; Iimuro, Satoshi; Sakurai, Takashi; Umegaki, Hiroyuki; Iijima, Katsuya; Nakano, Hiroshi; Oba, Kenzo; Yokono, Koichi; Sone, Hirohito; Yamada, Nobuhiro; Ako, Junya; Kozaki, Koichi; Miura, Hisayuki; Kashiwagi, Atsunori; Kikkawa, Ryuichi; Yoshimura, Yukio; Nakano, Tadasumi; Ohashi, Yasuo; Ito, Hideki

2012-04-01

To evaluate the association of low-density lipoprotein, high-density lipoprotein and non-high-density lipoprotein cholesterol with the risk of stroke, diabetes-related vascular events and mortality in elderly diabetes patients. This study was carried out as a post-hoc landmark analysis of a randomized, controlled, multicenter, prospective intervention trial. We included 1173 elderly type 2 diabetes patients (aged ≥ 65 years) from 39 Japanese institutions who were enrolled in the Japanese elderly diabetes intervention trial study and who could be followed up for 1 year. A landmark survival analysis was carried out in which follow up was set to start 1 year after the initial time of entry. During 6 years of follow up, there were 38 cardiovascular events, 50 strokes, 21 diabetes-related deaths and 113 diabetes-related events. High low-density lipoprotein cholesterol was associated with incident cardiovascular events, and high glycated hemoglobin was associated with strokes. After adjustment for possible covariables, non-high-density lipoprotein cholesterol showed a significant association with increased risk of stroke, diabetes-related mortality and total events. The adjusted hazard ratios (95% confidence intervals) of non-high-density lipoprotein cholesterol were 1.010 (1.001-1.018, P = 0.029) for stroke, 1.019 (1.007-1.031, P < 0.001) for diabetes-related death and 1.008 (1.002-1.014; P < 0.001) for total diabetes-related events. Higher non-high-density lipoprotein cholesterol was associated with an increased risk of stroke, diabetes-related mortality and total events in elderly diabetes patients. © 2012 Japan Geriatrics Society.

Assessment of the correlation between insertion torque and resonance frequency analysis of implants placed in bone tissue of different densities.

PubMed

Filho, Luiz Carlos Magno; Cirano, Fabiano Ribeiro; Hayashi, Fernando; Feng, Hsu Shao; Conte, Alexandre; Dib, Luciano Lauria; Casati, Marcio Zaffalon

2014-06-01

The primary stability of dental implants is fundamental for osseointegration. Therefore, this study aimed to assess the correlation between insertion torque (IT) and resonance frequency analysis (RFA) of implants placed in mandibles and maxillas of different bone densities. Eighty dental implants were placed in maxillas and mandibles, and IT and the implant stability quotient (ISQ) were measured at the time of implant insertion. Bone density was assessed subjectively by the Lekholm and Zarb index. The type I and II densities were grouped together (group A)as were the type III and IV densities (group B). The IT in group A was higher (Student t test, P = .0013) than in group B (46.27 ± 18.51 Ncm, 33.62 ± 14.74 Ncm, respectively). The implants placed in group A showed higher ISQ (Student t test, P = .0004) than those placed in group B (70.09 ± 7.50, 63.66 ± 8.00, respectively). A significant correlation between IT and the ISQ value was observed for group A (Pearson correlation test; r = 0.35; P = .0213) and for group B (r = 0.37; P = .0224). Within the limitations of this study, it was possible to conclude that there is a correlation between IT and RFA of implants placed in mandibles and maxillas of different bone densities.

Analysis of geometric and electrochemical characteristics of lithium cobalt oxide electrode with different packing densities

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

Lim, Cheolwoong; Yan, Bo; Kang, Huixiao

2016-08-06

In order to investigate geometric and electrochemical characteristics of Li ion battery electrode with different packing densities, lithium cobalt oxide (LiCoO 2) cathode electrodes were fabricated from a 94:3:3 (wt%) mixture of LiCoO 2, polymeric binder, and super-P carbon black and calendered to different densities. A synchrotron X-ray nano-computed tomography system with a spatial resolution of 58.2 nm at the Advanced Photon Source of the Argonne National Laboratory was employed to obtain three dimensional morphology data of the electrodes. The morphology data were then quantitatively analyzed to characterize their geometric properties, such as porosity, tortuosity, specific surface area, and poremore » size distribution. The geometric and electrochemical analysis reveal that high packing density electrodes have smaller average pore size and narrower pore size distribution, which improves the electrical contact between carbon-binder matrix and LiCoO 2 particles. The better contact improves the capacity and rate capability by reducing the possibility of electrically isolated LiCoO 2 particles and increasing the electrochemically active area. The results show that increase of packing density results in higher tortuosity, but electrochemically active area is more crucial to cell performance than tortuosity at up to 3.6 g/cm 3 packing density and 4 C rate.« less

Effect of density gradients in confined supersonic shear layers, part 1

NASA Astrophysics Data System (ADS)

Peroomian, Oshin; Kelly, R. E.

1994-11-01

The effect of density gradients on the supersonic wall modes (acoustic modes) of a 2-D confined compressible shear layer were investigated using linear analysis. Due to the inadequacies of the hyperbolic tangent profile, the boundary layer basic profiles were used. First a test case was taken with the same parameters as in Tam and Hu's analysis with convective Mach number M(sub c) = 1.836 and density ratio of 1.398. Three generalized inflection points were found giving rise to three modes. The first two show similar properties to the Class A and B modes, and the third is an 'inner mode' which will be called a Class C mode. As the density ratio is increased, the smallest of the three neutral phase speeds tends towards the speed of the lower velocity stream, and the other two eventually coalesce and then disappear. These two effects lead to a linear resonance between the Class B modes which increases the cutoff frequency and growth rate of the lowest mode. In fact, growth rates of 2-4 times the test case were found as the density ratio was increased to 7. A similar trend is observed for the Class A modes when the density ratio is decreased from the test case, but the growth rate is not changed by much from the test case.

Reader performance in visual assessment of breast density using visual analogue scales: Are some readers more predictive of breast cancer?

NASA Astrophysics Data System (ADS)

Rayner, Millicent; Harkness, Elaine F.; Foden, Philip; Wilson, Mary; Gadde, Soujanya; Beetles, Ursula; Lim, Yit Y.; Jain, Anil; Bundred, Sally; Barr, Nicky; Evans, D. Gareth; Howell, Anthony; Maxwell, Anthony; Astley, Susan M.

2018-03-01

Mammographic breast density is one of the strongest risk factors for breast cancer, and is used in risk prediction and for deciding appropriate imaging strategies. In the Predicting Risk Of Cancer At Screening (PROCAS) study, percent density estimated by two readers on Visual Analogue Scales (VAS) has shown a strong relationship with breast cancer risk when assessed against automated methods. However, this method suffers from reader variability. This study aimed to assess the performance of PROCAS readers using VAS, and to identify those most predictive of breast cancer. We selected the seven readers who had estimated density on over 6,500 women including at least 100 cancer cases, analysing their performance using multivariable logistic regression and Receiver Operator Characteristic (ROC) analysis. All seven readers showed statistically significant odds ratios (OR) for cancer risk according to VAS score after adjusting for classical risk factors. The OR was greatest for reader 18 at 1.026 (95% Cl 1.018-1.034). Adjusted Area Under the ROC Curves (AUCs) were statistically significant for all readers, but greatest for reader 14 at 0.639. Further analysis of the VAS scores for these two readers showed reader 14 had higher sensitivity (78.0% versus 42.2%), whereas reader 18 had higher specificity (78.0% versus 46.0%). Our results demonstrate individual differences when assigning VAS scores; one better identified those with increased risk, whereas another better identified low risk individuals. However, despite their different strengths, both readers showed similar predictive abilities overall. Standardised training for VAS may improve reader variability and consistency of VAS scoring.

Study of the second magnetization peak and the pinning behaviour in Ba(Fe0.935Co0.065)2As2 pnictide superconductor

NASA Astrophysics Data System (ADS)

Sundar, Shyam; Mosqueira, J.; Alvarenga, A. D.; Sóñora, D.; Sefat, A. S.; Salem-Sugui, S., Jr.

2017-12-01

Isothermal magnetic field dependence of magnetization and magnetic relaxation measurements were performed for the H\\parallel {{c}} axis on a single crystal of Ba(Fe0.935 Co0.065)2As2 pnictide superconductor having T c = 21.7 K. The second magnetization peak (SMP) for each isothermal M(H) was observed in a wide temperature range from T c to the lowest temperature of measurement (2 K). The magnetic field dependence of relaxation rate R(H), showed a peak (H spt) between H on (onset of SMP in M(H)) and H p (peak field of SMP in M(H)), which is likely to be related to a vortex-lattice structural phase transition, as suggested in the literature for a similar sample. In addition, the magnetic relaxation measured for magnetic fields near H spt showed some noise, which might be the signature of the structural phase transition of the vortex lattice. Analysis of the magnetic relaxation data using Maley’s criterion and the collective pinning theory suggested that the SMP in the sample was due to the collective (elastic) to plastic creep crossover, which was also accompanied by a rhombic to square vortex lattice phase transition. Analysis of the pinning force density suggested a single dominating pinning mechanism in the sample, which did not showing the usual δ {l} and δ {T}{{c}} nature of pinning. The critical current density (J c), estimated using the Bean critical state model, was found to be 5 × 105 A cm- 2 at 2 K in the zero magnetic field limit. Surprisingly, the maximum of the pinning force density was not responsible for the maximum value of the critical current density in the sample.

Changes in bone tissue under conditions of hypokinesia and in connection with age

NASA Technical Reports Server (NTRS)

Podrushnyak, E. P.; Suslov, E. I.

1980-01-01

X-ray micrography was used to study the optical density of the blackening of X-ray photographs made of five bones in 9 young people (ages 24 to 29) before and after strict bed rest for 16 to 37 days. Photometric studies of the X-ray film determined the relative concentration of bone structure before and after hypokinesia. In addition, the bone tissues of 25 cadavers of practically healthy individuals (aged 18 to 70) who died from injuries were investigated using X-ray structural analysis. Results show that the reaction to the state of hypokinesia is not uniform in different individuals and is quite often directly reversed. It was established that pronounced osteoporosis can be found in a relatively short time after conditions of hypokinesia in healthy young individuals. Results show that the stabilization of the crystalline structure of hydroxyapatite, especially its crystal formation, is finished by the age of 20 to 25. From 25 to 60, the crystal lattice remains in stable condition but X-ray analysis shows a reduction in the hydroxyapatite density.

Application of response surface methodology for optimization of parameters for microwave heating of rare earth carbonates

NASA Astrophysics Data System (ADS)

Yin, Shaohua; Lin, Guo; Li, Shiwei; Peng, Jinhui; Zhang, Libo

2016-09-01

Microwave heating has been applied in the field of drying rare earth carbonates to improve drying efficiency and reduce energy consumption. The effects of power density, material thickness and drying time on the weight reduction (WR) are studied using response surface methodology (RSM). The results show that RSM is feasible to describe the relationship between the independent variables and weight reduction. Based on the analysis of variance (ANOVA), the model is in accordance with the experimental data. The optimum experiment conditions are power density 6 w/g, material thickness 15 mm and drying time 15 min, resulting in an experimental weight reduction of 73%. Comparative experiments show that microwave drying has the advantages of rapid dehydration and energy conservation. Particle analysis shows that the size distribution of rare earth carbonates after microwave drying is more even than those in an oven. Based on these findings, microwave heating technology has an important meaning to energy-saving and improvement of production efficiency for rare earth smelting enterprises and is a green heating process.

Endovascular image-guided treatment of in-vivo model aneurysms with asymmetric vascular stents (AVS): evaluation with time-density curve angiographic analysis and histology.

PubMed

Dohatcu, A; Ionita, C N; Paciorek, A; Bednarek, D R; Hoffmann, K R; Rudin, S

2008-01-01

In this study, we compare the results obtained from Time-Density Curve (TDC) analysis of angiographic imaging sequences with histological evaluation for a rabbit aneurysm model treated with standard stents and new asymmetric vascular stents (AVS) placed by image-guided endovascular deployment. AVSs are stents having a low-porosity patch region designed to cover the aneurysm neck and occlude blood flow inside. To evaluate the AVSs, rabbits with elastase-induced aneurysm models (n=20) were divided into three groups: the first (n=10) was treated with an AVS, the second (n=5) with a non-patch standard coronary stent, and third was untreated as a control (n=5). We used TDC analysis to measure how much contrast media entered the aneurysm before and after treatment. TDCs track contrast-media-density changes as a function of time over the region of interest in x-ray DSA cine-sequences. After 28 days, the animals were sacrificed and the explanted specimens were histologically evaluated. The first group showed an average reduction of contrast flow into the aneurysm of 95% after treatment with an AVS with fully developed thrombus at 28 days follow-up. The rabbits treated with standard stents showed an increase in TDC residency time after treatment and partial-thrombogenesis. The untreated control aneurysms displayed no reduction in flow and were still patent at follow-up. The quantitative TDC analysis findings were confirmed by histological evaluation suggesting that the new AVS has great potential as a definitive treatment for cerebro-vascular aneurysms and that angiographic TDC analysis can provide in-vivo verification.

Endovascular image-guided treatment of in-vivo model aneurysms with asymmetric vascular stents (AVS): evaluation with time-density curve angiographic analysis and histology

PubMed Central

Dohatcu, A.; Ionita, C. N.; Paciorek, A.; Bednarek, D. R.; Hoffmann, K. R.; Rudin, S.

2008-01-01

In this study, we compare the results obtained from Time-Density Curve (TDC) analysis of angiographic imaging sequences with histological evaluation for a rabbit aneurysm model treated with standard stents and new asymmetric vascular stents (AVS) placed by image-guided endovascular deployment. AVSs are stents having a low-porosity patch region designed to cover the aneurysm neck and occlude blood flow inside. To evaluate the AVSs, rabbits with elastase-induced aneurysm models (n=20) were divided into three groups: the first (n=10) was treated with an AVS, the second (n=5) with a non-patch standard coronary stent, and third was untreated as a control (n=5). We used TDC analysis to measure how much contrast media entered the aneurysm before and after treatment. TDCs track contrast-media-density changes as a function of time over the region of interest in x-ray DSA cine-sequences. After 28 days, the animals were sacrificed and the explanted specimens were histologically evaluated. The first group showed an average reduction of contrast flow into the aneurysm of 95% after treatment with an AVS with fully developed thrombus at 28 days follow-up. The rabbits treated with standard stents showed an increase in TDC residency time after treatment and partial-thrombogenesis. The untreated control aneurysms displayed no reduction in flow and were still patent at follow-up. The quantitative TDC analysis findings were confirmed by histological evaluation suggesting that the new AVS has great potential as a definitive treatment for cerebro-vascular aneurysms and that angiographic TDC analysis can provide in-vivo verification. PMID:18958295

Ultra-stiff metallic glasses through bond energy density design.

PubMed

Schnabel, Volker; Köhler, Mathias; Music, Denis; Bednarcik, Jozef; Clegg, William J; Raabe, Dierk; Schneider, Jochen M

2017-07-05

The elastic properties of crystalline metals scale with their valence electron density. Similar observations have been made for metallic glasses. However, for metallic glasses where covalent bonding predominates, such as metalloid metallic glasses, this relationship appears to break down. At present, the reasons for this are not understood. Using high energy x-ray diffraction analysis of melt spun and thin film metallic glasses combined with density functional theory based molecular dynamics simulations, we show that the physical origin of the ultrahigh stiffness in both metalloid and non-metalloid metallic glasses is best understood in terms of the bond energy density. Using the bond energy density as novel materials design criterion for ultra-stiff metallic glasses, we are able to predict a Co 33.0 Ta 3.5 B 63.5 short range ordered material by density functional theory based molecular dynamics simulations with a high bond energy density of 0.94 eV Å -3 and a bulk modulus of 263 GPa, which is 17% greater than the stiffest Co-B based metallic glasses reported in literature.

Heartwood and sapwood in eucalyptus trees: non-conventional approach to wood quality.

PubMed

Cherelli, Sabrina G; Sartori, Maria Márcia P; Próspero, André G; Ballarin, Adriano W

2018-01-01

This study evaluated the quality of heartwood and sapwood from mature trees of three species of Eucalyptus, by means of the qualification of their proportion, determination of basic and apparent density using non-destructive attenuation of gamma radiation technique and calculation of the density uniformity index. Six trees of each species (Eucalyptus grandis - 18 years old, Eucalyptus tereticornis - 35 years old and Corymbia citriodora - 28 years old) were used in the experimental program. The heartwood and sapwood were delimited by macroscopic analysis and the calculation of areas and percentage of heartwood and sapwood were performed using digital image. The uniformity index was calculated following methodology which numerically quantifies the dispersion of punctual density values of the wood around the mean density along the radius. The percentage of the heartwood was higher than the sapwood in all species studied. The density results showed no statistical difference between heartwood and sapwood. Differently from the density results, in all species studied there was statistical differences between uniformity indexes for heartwood and sapwood regions, making justifiable the inclusion of the density uniformity index as a quality parameter for Eucalyptus wood.

Intermolecular interaction in nucleobases and dimethyl sulfoxide/water molecules: A DFT, NBO, AIM and NCI analysis.

PubMed

Venkataramanan, Natarajan Sathiyamoorthy; Suvitha, Ambigapathy; Kawazoe, Yoshiyuki

2017-11-01

This study aims to cast light on the physico-chemical nature and energetics of interactions between the nucleobases and water/DMSO molecules which occurs through the non-conventional CH⋯O/N-H bonds using a comprehensive quantum-chemical approach. The computed interaction energies do not show any appreciable change for all the nucleobase-solvent complexes, conforming the experimental findings on the hydration enthalpies. Compared to water, DMSO form complexes with high interaction energies. The quantitative molecular electrostatic potentials display a charge transfer during the complexation. NBO analysis shows the nucleobase-DMSO complexes, have higher stabilization energy values than the nucleobase-water complexes. AIM analysis illustrates that the in the nucleobase-DMSO complexes, SO⋯H-N type interaction have strongest hydrogen bond strength with high E HB values. Furthermore, the Laplacian of electron density and total electron density were negative indicating the partial covalent nature of bonding in these systems, while the other bonds are classified as noncovalent interactions. EDA analysis indicates, the electrostatic interaction is more pronounced in the case of nucleobase-water complexes, while the dispersion contribution is more dominant in nucleobase-DMSO complexes. NCI-RDG analysis proves the existence of strong hydrogen bonding in nucleobase-DMSO complex, which supports the AIM results. Copyright © 2017 Elsevier Inc. All rights reserved.

Corneal Structural Changes in Nonneoplastic and Neoplastic Monoclonal Gammopathies.

PubMed

Aragona, Pasquale; Allegra, Alessandro; Postorino, Elisa Imelde; Rania, Laura; Innao, Vanessa; Wylegala, Edward; Nowinska, Anna; Ieni, Antonio; Pisani, Antonina; Musolino, Caterina; Puzzolo, Domenico; Micali, Antonio

2016-05-01

To investigate corneal confocal microscopic changes in nonneoplastic and neoplastic monoclonal gammopathies. Three groups of subjects were considered: group 1, twenty normal subjects; group 2, fifteen patients with monoclonal gammopathy of undetermined significance (MGUS); group 3, eight patients with smoldering multiple myeloma and eight patients with untreated multiple myeloma. After hematologic diagnosis, patients underwent ophthalmologic exam and in vivo confocal microscopic study. The statistical analysis was performed using ANOVA and Student-Newman-Keuls tests and receiver operating characteristic (ROC) curve analysis. Epithelial cells of gammopathic patients showed significantly higher reflectivity than controls, demonstrated by optical density (P < 0.001). Subbasal nerve density, branching, and beading were significantly altered in gammopathic patients (P = 0.01, P = 0.02, P = 0.02, respectively). The number of keratocytes was significantly reduced in neoplastic patients (P < 0.001 versus both normal and MGUS) in the anterior, medium, and posterior stroma. The ROC curve analysis showed good sensitivity and specificity for this parameter. Group 2 and 3 keratocytes showed higher nuclear and cytoplasmatic reflectivity in the medium and posterior stroma. Endothelial cells were not affected. Patients with neoplastic gammopathies showed peculiar alterations of the keratocyte number, which appeared significantly reduced. A follow-up with corneal confocal microscopy of patients with MGUS is suggested as a useful tool to identify peripheral tissue alterations linked to possible neoplastic disease development.

Arctic Intermediate Water in the Nordic Seas, 1991-2009

NASA Astrophysics Data System (ADS)

Jeansson, Emil; Olsen, Are; Jutterström, Sara

2017-10-01

The evolution of the different types of Arctic Intermediate Water (AIW) in the Nordic Seas is evaluated and compared utilising hydro-chemical data from 1991 to 2009. It has been suggested that these waters are important components of the Norwegian Sea Arctic Intermediate Water (NSAIW), and of the dense overflows to the North Atlantic. Thus, it is important to understand how their properties and distribution vary with time. The AIWs from the Greenland and Iceland Seas, show different degrees of variability during the studied period; however, only the Greenland Sea Arctic Intermediate Water (GSAIW) shows an increasing temperature and salinity throughout the 2000s, which considerably changed the properties of this water mass. Optimum multiparameter (OMP) analysis was conducted to assess the sources of the NSAIW. The analysis shows that the Iceland Sea Arctic Intermediate Water (ISAIW) and the GSAIW both contribute to NSAIW, at different densities corresponding to their respective density range. This illustrates that they flow largely isopycnally from their source regions to the Norwegian Sea. The main source of the NSAIW, however, is the upper Polar Deep Water, which explains the lower concentrations of oxygen and chlorofluorocarbons, and higher salinity and nutrient concentrations of the NSAIW layer compared with the ISAIW and GSAIW. This shows how vital it is to include chemical tracers in any water mass analysis to correctly assess the sources of the water mass being studied.

[Principles of bone tissue structures interaction with full removable dentures fixed on intraosseous implantates modelling].

PubMed

Shashmurina, V R; Chumachenko, E N; Olesova, V N; Volozhin, A I

2008-01-01

Math modelling "removable dentures-implantate-bone" with size and density of bone tissue as variables was created. It allowed to study biomechanical bases of mandibular bone tissue structures interaction with full removable dentures of different constructions and fixed on intraosseous implantates. Analysis of the received data showed that in the majority of cases it was expedient to recommend 3 bearing (abutments) system of denture making. Rest on 4 and more implantates was appropriate for patients with reduced density of spongy bone and significant mandibular bone atrophy. 2 abutment system can be used in patients with high density of spongy bone and absence of mandibular bone atrophy.

The calculations of small molecular conformation energy differences by density functional method

NASA Astrophysics Data System (ADS)

Topol, I. A.; Burt, S. K.

1993-03-01

The differences in the conformational energies for the gauche (G) and trans(T) conformers of 1,2-difluoroethane and for myo-and scyllo-conformer of inositol have been calculated by local density functional method (LDF approximation) with geometry optimization using different sets of calculation parameters. It is shown that in the contrast to Hartree—Fock methods, density functional calculations reproduce the correct sign and value of the gauche effect for 1,2-difluoroethane and energy difference for both conformers of inositol. The results of normal vibrational analysis for1,2-difluoroethane showed that harmonic frequencies calculated in LDF approximation agree with experimental data with the accuracy typical for scaled large basis set Hartree—Fock calculations.

A density-functional-theory study of biradicals from benzene to hexacene

NASA Astrophysics Data System (ADS)

Kim, Hyun-Jung; Wang, Xingyong; Ma, Jing; Cho, Jun-Hyung

2011-11-01

The singlet-triplet energy gap of biradicals created in benzene and polyacenes is investigated by density-functional-theory calculations. For the biradicals in benzene, naphthalene, anthracene, tetracene, pentacene, and hexacene, we find that the singlet state is energetically favored over the triplet state by 189, 191, 184, 199, 218, and 244 meV, respectively. The monotonous increase of the singlet-triplet energy gap from anthracene to hexacene is attributed to the enhanced stability of the singlet state for longer polyacenes. Our analysis shows that the spin density of the singlet state is delocalized over all benzene rings, but such a spin delocalization is not present for the triplet state.

Multiphysical simulation analysis of the dislocation structure in germanium single crystals

NASA Astrophysics Data System (ADS)

Podkopaev, O. I.; Artemyev, V. V.; Smirnov, A. D.; Mamedov, V. M.; Sid'ko, A. P.; Kalaev, V. V.; Kravtsova, E. D.; Shimanskii, A. F.

2016-09-01

To grow high-quality germanium crystals is one of the most important problems of growth industry. The dislocation density is an important parameter of the quality of single crystals. The dislocation densities in germanium crystals 100 mm in diameter, which have various shapes of the side surface and are grown by the Czochralski technique, are experimentally measured. The crystal growth is numerically simulated using heat-transfer and hydrodynamics models and the Alexander-Haasen dislocation model in terms of the CGSim software package. A comparison of the experimental and calculated dislocation densities shows that the dislocation model can be applied to study lattice defects in germanium crystals and to improve their quality.

A simple method for the extraction and identification of light density microplastics from soil.

PubMed

Zhang, Shaoliang; Yang, Xiaomei; Gertsen, Hennie; Peters, Piet; Salánki, Tamás; Geissen, Violette

2018-03-01

This article introduces a simple and cost-saving method developed to extract, distinguish and quantify light density microplastics of polyethylene (PE) and polypropylene (PP) in soil. A floatation method using distilled water was used to extract the light density microplastics from soil samples. Microplastics and impurities were identified using a heating method (3-5s at 130°C). The number and size of particles were determined using a camera (Leica DFC 425) connected to a microscope (Leica wild M3C, Type S, simple light, 6.4×). Quantification of the microplastics was conducted using a developed model. Results showed that the floatation method was effective in extracting microplastics from soils, with recovery rates of approximately 90%. After being exposed to heat, the microplastics in the soil samples melted and were transformed into circular transparent particles while other impurities, such as organic matter and silicates were not changed by the heat. Regression analysis of microplastics weight and particle volume (a calculation based on image J software analysis) after heating showed the best fit (y=1.14x+0.46, R 2 =99%, p<0.001). Recovery rates based on the empirical model method were >80%. Results from field samples collected from North-western China prove that our method of repetitive floatation and heating can be used to extract, distinguish and quantify light density polyethylene microplastics in soils. Microplastics mass can be evaluated using the empirical model. Copyright © 2017 Elsevier B.V. All rights reserved.

Construction of a High-Density Genetic Map from RNA-Seq Data for an Arabidopsis Bay-0 × Shahdara RIL Population

PubMed Central

Serin, Elise A. R.; Snoek, L. B.; Nijveen, Harm; Willems, Leo A. J.; Jiménez-Gómez, Jose M.; Hilhorst, Henk W. M.; Ligterink, Wilco

2017-01-01

High-density genetic maps are essential for high resolution mapping of quantitative traits. Here, we present a new genetic map for an Arabidopsis Bayreuth × Shahdara recombinant inbred line (RIL) population, built on RNA-seq data. RNA-seq analysis on 160 RILs of this population identified 30,049 single-nucleotide polymorphisms (SNPs) covering the whole genome. Based on a 100-kbp window SNP binning method, 1059 bin-markers were identified, physically anchored on the genome. The total length of the RNA-seq genetic map spans 471.70 centimorgans (cM) with an average marker distance of 0.45 cM and a maximum marker distance of 4.81 cM. This high resolution genotyping revealed new recombination breakpoints in the population. To highlight the advantages of such high-density map, we compared it to two publicly available genetic maps for the same population, comprising 69 PCR-based markers and 497 gene expression markers derived from microarray data, respectively. In this study, we show that SNP markers can effectively be derived from RNA-seq data. The new RNA-seq map closes many existing gaps in marker coverage, saturating the previously available genetic maps. Quantitative trait locus (QTL) analysis for published phenotypes using the available genetic maps showed increased QTL mapping resolution and reduced QTL confidence interval using the RNA-seq map. The new high-density map is a valuable resource that facilitates the identification of candidate genes and map-based cloning approaches. PMID:29259624

Scale-invariant puddles in graphene: Geometric properties of electron-hole distribution at the Dirac point.

PubMed

Najafi, M N; Nezhadhaghighi, M Ghasemi

2017-03-01

We characterize the carrier density profile of the ground state of graphene in the presence of particle-particle interaction and random charged impurity in zero gate voltage. We provide detailed analysis on the resulting spatially inhomogeneous electron gas, taking into account the particle-particle interaction and the remote Coulomb disorder on an equal footing within the Thomas-Fermi-Dirac theory. We present some general features of the carrier density probability measure of the graphene sheet. We also show that, when viewed as a random surface, the electron-hole puddles at zero chemical potential show peculiar self-similar statistical properties. Although the disorder potential is chosen to be Gaussian, we show that the charge field is non-Gaussian with unusual Kondev relations, which can be regarded as a new class of two-dimensional random-field surfaces. Using Schramm-Loewner (SLE) evolution, we numerically demonstrate that the ungated graphene has conformal invariance and the random zero-charge density contours are SLE_{κ} with κ=1.8±0.2, consistent with c=-3 conformal field theory.

FT-IR and Raman spectra, DFT and SQMFF calculations for geometrical interpretation and vibrational analysis of 3-nitro-p-toluic acid

NASA Astrophysics Data System (ADS)

Nataraj, A.; Balachandran, V.; Karthick, T.

2012-08-01

The Fourier transform infrared (FT-IR) and FT-Raman of 3-nitro-p-toluic acid (NTA) have been recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been investigated with the help of ab initio and density functional theory (DFT) methods. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The optimized geometric bond lengths and bond angles obtained by computation show good agreement with experimental data of the relative compound. The computed dimer parameters also show good agreement with experimental data. The first hyperpolarizability (β0) of this noval molecular system and related properties (β, α0, and Δα) of NTA are calculated using B3LYP/6-311++G(d,p) method on the finite-field approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* and π* antibonding orbital and second order delocalization energies E(2) confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. The calculated HOMO and LUMO energies also show that charge transfer occurs within the molecule. Finally the calculations results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra.

Prevalence, pattern, and determinants of placental malaria in a population of southeastern Nigerian parturients.

PubMed

Ezebialu, Ifeanyichukwu U; Eke, Ahizechukwu C; Ezeagwuna, Dorothy A; Nwachukwu, Chukwuemeka E; Ifediata, Francis; Ezebialu, Chinenye U

2012-12-01

Placental malaria is a complication of malaria in pregnancy and is associated with adverse outcomes. Its burden is highest in Sub-Saharan Africa, but despite this, data based on histological analysis are scarce from this region. Questionnaires administered by the researchers were used to obtain information from parturients at a university teaching hospital in southeastern Nigeria between April and November 2010. Maternal blood and placental blood were collected for analysis. Placental blocks were taken for histological analysis. Statistical analyses were done using SPSS v. 17. Three hundred and sixty-five placentas were analyzed, out of which 254 showed histological evidence of malaria parasitization, giving a prevalence of 69.6%. Of the 254 placentas, 23 (9.0%) showed active infection and 196 (77.2%) showed active-on-past infection, while 35 (13.8%) showed past infection. Rural residence, hemoglobin genotype AA, not receiving intermittent preventive treatment in pregnancy (IPTp), and not sleeping under insecticide-treated bed nets (ITN) were significantly associated with placental malaria. Placental parasite density was inversely related to parity. This study showed that the prevalence of placental malaria in southeastern Nigeria is high, and demonstrated that the mean parasite density was inversely related to parity. Significant factors associated with placental malaria were also identified. Appreciation of these significant factors will assist program managers in implementing the strategies for the prevention of malaria in pregnancy. Copyright © 2012 International Society for Infectious Diseases. All rights reserved.

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.

Dynamical system analysis of interacting models

NASA Astrophysics Data System (ADS)

Carneiro, S.; Borges, H. A.

2018-01-01

We perform a dynamical system analysis of a cosmological model with linear dependence between the vacuum density and the Hubble parameter, with constant-rate creation of dark matter. We show that the de Sitter spacetime is an asymptotically stable critical point, future limit of any expanding solution. Our analysis also shows that the Minkowski spacetime is an unstable critical point, which eventually collapses to a singularity. In this way, such a prescription for the vacuum decay not only predicts the correct future de Sitter limit, but also forbids the existence of a stable Minkowski universe. We also study the effect of matter creation on the growth of structures and their peculiar velocities, showing that it is inside the current errors of redshift space distortions observations.

SU-E-T-470: Importance of HU-Mass Density Calibration Technique in Proton Pencil Beam Dose Calculation

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

Penfold, S; Miller, A

2015-06-15

Purpose: Stoichiometric calibration of Hounsfield Units (HUs) for conversion to proton relative stopping powers (RStPs) is vital for accurate dose calculation in proton therapy. However proton dose distributions are not only dependent on RStP, but also on relative scattering power (RScP) of patient tissues. RScP is approximated from material density but a stoichiometric calibration of HU-density tables is commonly neglected. The purpose of this work was to quantify the difference in calculated dose of a commercial TPS when using HU-density tables based on tissue substitute materials and stoichiometric calibrated ICRU tissues. Methods: Two HU-density calibration tables were generated based onmore » scans of the CIRS electron density phantom. The first table was based directly on measured HU and manufacturer quoted density of tissue substitute materials. The second was based on the same CT scan of the CIRS phantom followed by a stoichiometric calibration of ICRU44 tissue materials. The research version of Pinnacle{sup 3} proton therapy was used to compute dose in a patient CT data set utilizing both HU-density tables. Results: The two HU-density tables showed significant differences for bone tissues; the difference increasing with increasing HU. Differences in density calibration table translated to a difference in calculated RScP of −2.5% for ICRU skeletal muscle and 9.2% for ICRU femur. Dose-volume histogram analysis of a parallel opposed proton therapy prostate plan showed that the difference in calculated dose was negligible when using the two different HU-density calibration tables. Conclusion: The impact of HU-density calibration technique on proton therapy dose calculation was assessed. While differences were found in the calculated RScP of bony tissues, the difference in dose distribution for realistic treatment scenarios was found to be insignificant.« less

A method to describe inelastic gamma field distribution in neutron gamma density logging.

PubMed

Zhang, Feng; Zhang, Quanying; Liu, Juntao; Wang, Xinguang; Wu, He; Jia, Wenbao; Ti, Yongzhou; Qiu, Fei; Zhang, Xiaoyang

2017-11-01

Pulsed neutron gamma density logging (NGD) is of great significance for radioprotection and density measurement in LWD, however, the current methods have difficulty in quantitative calculation and single factor analysis for the inelastic gamma field distribution. In order to clarify the NGD mechanism, a new method is developed to describe the inelastic gamma field distribution. Based on the fast-neutron scattering and gamma attenuation, the inelastic gamma field distribution is characterized by the inelastic scattering cross section, fast-neutron scattering free path, formation density and other parameters. And the contribution of formation parameters on the field distribution is quantitatively analyzed. The results shows the contribution of density attenuation is opposite to that of inelastic scattering cross section and fast-neutron scattering free path. And as the detector-spacing increases, the density attenuation gradually plays a dominant role in the gamma field distribution, which means large detector-spacing is more favorable for the density measurement. Besides, the relationship of density sensitivity and detector spacing was studied according to this gamma field distribution, therefore, the spacing of near and far gamma ray detector is determined. The research provides theoretical guidance for the tool parameter design and density determination of pulsed neutron gamma density logging technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

Finite element analysis of space debris removal by high-power lasers

NASA Astrophysics Data System (ADS)

Xue, Li; Jiang, Guanlei; Yu, Shuang; Li, Ming

2015-08-01

With the development of space station technologies, irradiation of space debris by space-based high-power lasers, can locally generate high-temperature plasmas and micro momentum, which may achieve the removal of debris through tracking down. Considered typical square-shaped space debris of material Ti with 5cm×5cm size, whose thermal conductivity, density, specific heat capacity and emissivity are 7.62W/(m·°C), 4500kg/m3, 0.52J/(kg·°C) and 0.3,respectively, based on the finite element analysis of ANSYS, each irradiation of space debris by high-power lasers with power density 106W/m2 and weapons-grade lasers with power density 3000W/m2 are simulated under space environment, and the temperature curves due to laser thermal irradiation are obtained and compared. Results show only 2s is needed for high-power lasers to make the debris temperature reach to about 10000K, which is the threshold temperature for plasmas-state conversion. While for weapons-grade lasers, it is 13min needed. Using two line elements (TLE), and combined with the coordinate transformation from celestial coordinate system to site coordinate system, the visible period of space debris is calculated as 5-10min. That is, in order to remove space debris by laser plasmas, the laser power density should be further improved. The article provides an intuitive and visual feasibility analysis method of space debris removal, and the debris material and shape, laser power density and spot characteristics are adjustable. This finite element analysis method is low-cost, repeatable and adaptable, which has an engineering-prospective applications.

The association of very-low-density lipoprotein with ankle-brachial index in peritoneal dialysis patients with controlled serum low-density lipoprotein cholesterol level

PubMed Central

2013-01-01

Background Peripheral artery disease (PAD) represents atherosclerotic disease and is a risk factor for death in peritoneal dialysis (PD) patients, who tend to show an atherogenic lipid profile. In this study, we investigated the relationship between lipid profile and ankle-brachial index (ABI) as an index of atherosclerosis in PD patients with controlled serum low-density lipoprotein (LDL) cholesterol level. Methods Thirty-five PD patients, whose serum LDL cholesterol level was controlled at less than 120mg/dl, were enrolled in this cross-sectional study in Japan. The proportions of cholesterol level to total cholesterol level (cholesterol proportion) in 20 lipoprotein fractions and the mean size of lipoprotein particles were measured using an improved method, namely, high-performance gel permeation chromatography. Multivariate linear regression analysis was adjusted for diabetes mellitus and cardiovascular and/or cerebrovascular diseases. Results The mean (standard deviation) age was 61.6 (10.5) years; PD vintage, 38.5 (28.1) months; ABI, 1.07 (0.22). A low ABI (0.9 or lower) was observed in 7 patients (low-ABI group). The low-ABI group showed significantly higher cholesterol proportions in the chylomicron fraction and large very-low-density lipoproteins (VLDLs) (Fractions 3–5) than the high-ABI group (ABI>0.9). Adjusted multivariate linear regression analysis showed that ABI was negatively associated with serum VLDL cholesterol level (parameter estimate=-0.00566, p=0.0074); the cholesterol proportions in large VLDLs (Fraction 4, parameter estimate=-3.82, p=0.038; Fraction 5, parameter estimate=-3.62, p=0.0039) and medium VLDL (Fraction 6, parameter estimate=-3.25, p=0.014); and the size of VLDL particles (parameter estimate=-0.0352, p=0.032). Conclusions This study showed that the characteristics of VLDL particles were associated with ABI among PD patients. Lowering serum VLDL level may be an effective therapy against atherosclerosis in PD patients after the control of serum LDL cholesterol level. PMID:24093487

Aggregated low-density lipoprotein induces LRP1 stabilization through E3 ubiquitin ligase CHFR downregulation in human vascular smooth muscle cells.

PubMed

Cal, Roi; García-Arguinzonis, Maisa; Revuelta-López, Elena; Castellano, José; Padró, Teresa; Badimon, Lina; Llorente-Cortés, Vicenta

2013-02-01

Low density lipoprotein retention and aggregation in the arterial intima are key processes in atherogenesis. Aggregated LDL (agLDL) is taken up through low-density lipoprotein receptor-related protein 1 (LRP1) by human vascular smooth muscle cells (VSMC). AgLDL increases LRP1 expression, at least in part, by downregulation of sterol regulatory element-binding proteins. It is unknown whether agLDL has some effect on the ubiquitin-proteasome system, and therefore on the LRP1 receptor turnover. The objective of this study was to analyze the effect of agLDL on the degradation of LRP1 by the ubiquitin-proteasome system in human VSMC. Human VSMC were isolated from the media of human coronary arteries. Ubiquitinylated LRP1 protein levels were significantly reduced in human VSMC exposed to agLDL (100 μg/mL) for 20 hours (agLDL: 3.70±0.44 a.u. versus control: 9.68±0.55 a.u). Studies performed with cycloheximide showed that agLDL prolongs the LRP1 protein half life. Pulse-chase analysis showed that LRP1 turnover rate is reduced in agLDL-exposed VSMC. Two-dimensional electrophoresis shows an alteration in the proteomic profile of a RING type E3 ubiquitin ligase, CHFR. Real-time PCR and Western blot analysis showed that agLDL (100 μg/mL) decreased the transcriptional and protein expression of CHFR. CHFR silencing increased VSMC, but not macrophage, LRP1 expression. However, CHFR silencing did not exert any effect on the classical low-density lipoprotein receptor protein levels. Furthermore, immunoprecipitation experiments demonstrated that the physical interaction between CHFR and LRP1 decreased in the presence of agLDL. Our results demonstrate that agLDL prolongs the half life of LRP1 by preventing the receptor ubiquitinylation, at least in part, through CHFR targeting. This mechanism seems to be specific for LRP1 and VSMC.

Hybrid density functional study on the mechanism for the enhanced photocatalytic properties of the ultrathin hybrid layered nanocomposite g-C3N4/BiOCl

NASA Astrophysics Data System (ADS)

Yao, Wenzhi; Zhang, Jihua; Wang, Yuanxu; Ren, Fengzhu

2018-03-01

To investigate the origin of the high photocatalytic performance of experimentally synthesized g-C3N4/ BiOCl, we studied its geometry structure, electronic structure, and photocatalytic properties by means of hybrid density-functional theory (DFT). The calculated band alignment of g-C3N4 and few-layer BiOCl sheets clearly shows that g-C3N4/ BiOCl is a standard type-II nanocomposite. The density of states, Bader charge, partial charge density, charge density difference, and the effective masses show that electron-hole pair can be effectively separated in the g-C3N4/BiOCl interface. The calculated absorption coefficients indicate an obvious redshift of the absorption edge. The band gap of g-C3N4/BiOCl can be modulated by external electric field, and a semiconductor-semimetal transition is observed. The type-II vdW heterostructure is still maintained during the changes of external electric field. Especially, when the electric field reaches to +0.7 V/Å, the impurity states have been eliminated with the band gap of 2.3 eV. An analysis of optical properties shows that the absorption coefficient in the visible-light region is enhanced considerably as the electric-field strength increases. Our calculation results suggest that the ultrathin hybrid layered g-C3N4/BiOCl nanocomposite may have significant advantages for visible-light photocatalysis.

Trabecular architecture in the sciuromorph femoral head: allometry and functional adaptation.

PubMed

Mielke, Maja; Wölfer, Jan; Arnold, Patrick; van Heteren, Anneke H; Amson, Eli; Nyakatura, John A

2018-01-01

Sciuromorpha (squirrels and close relatives) are diverse in terms of body size and locomotor behavior. Individual species are specialized to perform climbing, gliding or digging behavior, the latter being the result of multiple independent evolutionary acquisitions. Each lifestyle involves characteristic loading patterns acting on the bones of sciuromorphs. Trabecular bone, as part of the bone inner structure, adapts to such loading patterns. This network of thin bony struts is subject to bone modeling, and therefore reflects habitual loading throughout lifetime. The present study investigates the effect of body size and lifestyle on trabecular structure in Sciuromorpha. Based upon high-resolution computed tomography scans, the femoral head 3D inner microstructure of 69 sciuromorph species was analyzed. Species were assigned to one of the following lifestyle categories: arboreal, aerial, fossorial and semifossorial. A cubic volume of interest was selected in the center of each femoral head and analyzed by extraction of various parameters that characterize trabecular architecture (degree of anisotropy, bone volume fraction, connectivity density, trabecular thickness, trabecular separation, bone surface density and main trabecular orientation). Our analysis included evaluation of the allometric signals and lifestyle-related adaptation in the trabecular parameters. We show that bone surface density, bone volume fraction, and connectivity density are subject to positive allometry, and degree of anisotropy, trabecular thickness, and trabecular separation to negative allometry. The parameters connectivity density, bone surface density, trabecular thickness, and trabecular separation show functional signals which are related to locomotor behavior. Aerial species are distinguished from fossorial ones by a higher trabecular thickness, lower connectivity density and lower bone surface density. Arboreal species are distinguished from semifossorial ones by a higher trabecular separation. This study on sciuromorph trabeculae supplements the few non-primate studies on lifestyle-related functional adaptation of trabecular bone. We show that the architecture of the femoral head trabeculae in Sciuromorpha correlates with body mass and locomotor habits. Our findings provide a new basis for experimental research focused on functional significance of bone inner microstructure.

Characterization of the low latitude plasma density irregularities observed using C/NOFS and SCINDA data

NASA Astrophysics Data System (ADS)

Andima, Geoffrey; Amabayo, Emirant B.; Jurua, Edward; Cilliers, Pierre J.

2018-01-01

Complex electrodynamic processes over the low latitude region often result in post sunset plasma density irregularities which degrade satellite communication and navigation. In order to forecast the density irregularities, their occurrence time, duration and location need to be quantified. Data from the Communication/Navigation Outage Forecasting System (C/NOFS) satellite was used to characterize the low latitude ion density irregularities from 2011 to 2013. This was supported by ground based data from the SCIntillation Network Decision Aid (SCINDA) receivers at Makerere (Geographic coordinate 32.6°E, 0.3°N, and dip latitude -9.3°N) and Nairobi (Geographic coordinate 36.8°E, -1.3°N, and dip latitude -10.8°N). The results show that irregularities in ion density have a daily pattern with peaks from 20:00 to 24:00 Local Time (LT). Scintillation activity at L band and VHF over East Africa peaked in 2011 and 2012 from 20:00 to 24:00 LT, though in many cases scintillation at VHF persisted longer than that at L band. A longitudinal pattern in ion density irregularity occurrence was observed with peaks over 135-180°E and 270-300°E. The likelihood of ion density irregularity occurrence decreased with increasing altitude. Analysis of C/NOFS zonal ion drift velocities showed that the largest nighttime and daytime drifts were in 270-300°E and 300-330°E longitude regions respectively. Zonal irregularity drift velocities over East Africa were for the first time estimated from L-band scintillation indices. The results show that the velocity of plasma density irregularities in 2011 and 2012 varied daily, and hourly in the range of 50-150 m s-1. The zonal drift velocity estimates from the L-band scintillation indices had good positive correlation with the zonal drift velocities derived from VHF receivers by the spaced receiver technique.

Improved density profile measurements in the C-2U advanced beam-driven Field-Reversed Configuration (FRC) plasmas

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

Beall, M., E-mail: mbeall@trialphaenergy.com; Deng, B. H.; Gota, H.

2016-11-15

In the prior C-2 experiment, electron density was measured using a two-color 6-chord CO{sub 2}/HeNe interferometer. Analysis shows that high-frequency common mode phase noise can be reduced by a factor of 3 by constructing a reference chord. In the system upgrade from C-2 to C-2U a 4-chord far-infrared laser interferometer was developed, which demonstrated superior sensitivity (1 × 10{sup 16} m{sup −2} at >1 MHz bandwidth) and solved the under spatial sampling issue of the C-2 interferometer system. Improved density-profile measurement results are presented in this paper, including evidence of fast-ion modified density profile and stabilization of the n =more » 1 plasma wobble mode.« less

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

Gim, Yongwan; Kim, Wontae, E-mail: yongwan89@sogang.ac.kr, E-mail: wtkim@sogang.ac.kr

In warm inflation scenarios, radiation always exists, so that the radiation energy density is also assumed to be finite when inflation starts. To find out the origin of the non-vanishing initial radiation energy density, we revisit thermodynamic analysis for a warm inflation model and then derive an effective Stefan-Boltzmann law which is commensurate with the temperature-dependent effective potential by taking into account the non-vanishing trace of the total energy-momentum tensors. The effective Stefan-Boltzmann law shows that the zero energy density for radiation at the Grand Unification epoch increases until the inflation starts and it becomes eventually finite at the initialmore » stage of warm inflation. By using the above effective Stefan-Boltzmann law, we also study the cosmological scalar perturbation, and obtain the sufficient radiation energy density in order for GUT baryogenesis at the end of inflation.« less

Graphite fiber intercalation: Basic properties of copper chloride intercalated fibers

NASA Technical Reports Server (NTRS)

Jaworske, D. A.; Miller, J. D.

1986-01-01

In situ resistance measurements were used to follow the intercalation of copper chloride in pitch-based fibers. Subsequent single fiber resistivity measurements reveal a large range of resistivities, from 13 to 160 micro-ohms cm. Additional density measurements reveal a bimodal distribution of mass densities. The dense fibers have lower resistivities and correspond to the stage III compound identified by X-ray diffraction. Neither resistivity nor density correlate with diameter. Both energy dispersive spectroscopy and mass density data suggest that excess chlorine resides in the intercalated fiber, resulting in a stoichiometry of C4.9n CuCl2.5 (where n is the stage number) for the denser fibers. Finally, thermogravimetric analysis shows a 33 percent loss in mass upon heating to 700C. This loss in mass is attributed to loss of both chlorine and carbon.

Mangrove Habitat Use by Juvenile Reef Fish: Meta-Analysis Reveals that Tidal Regime Matters More than Biogeographic Region

PubMed Central

Igulu, Mathias M.; Nagelkerken, Ivan; Dorenbosch, Martijn; Grol, Monique G. G.; Harborne, Alastair R.; Kimirei, Ismael A.; Mumby, Peter J.; Olds, Andrew D.; Mgaya, Yunus D.

2014-01-01

Identification of critical life-stage habitats is key to successful conservation efforts. Juveniles of some species show great flexibility in habitat use while other species rely heavily on a restricted number of juvenile habitats for protection and food. Considering the rapid degradation of coastal marine habitats worldwide, it is important to evaluate which species are more susceptible to loss of juvenile nursery habitats and how this differs across large biogeographic regions. Here we used a meta-analysis approach to investigate habitat use by juvenile reef fish species in tropical coastal ecosystems across the globe. Densities of juvenile fish species were compared among mangrove, seagrass and coral reef habitats. In the Caribbean, the majority of species showed significantly higher juvenile densities in mangroves as compared to seagrass beds and coral reefs, while for the Indo-Pacific region seagrass beds harbored the highest overall densities. Further analysis indicated that differences in tidal amplitude, irrespective of biogeographic region, appeared to be the major driver for this phenomenon. In addition, juvenile reef fish use of mangroves increased with increasing water salinity. In the Caribbean, species of specific families (e.g. Lutjanidae, Haemulidae) showed a higher reliance on mangroves or seagrass beds as juvenile habitats than other species, whereas in the Indo-Pacific family-specific trends of juvenile habitat utilization were less apparent. The findings of this study highlight the importance of incorporating region-specific tidal inundation regimes into marine spatial conservation planning and ecosystem based management. Furthermore, the significant role of water salinity and tidal access as drivers of mangrove fish habitat use implies that changes in seawater level and rainfall due to climate change may have important effects on how juvenile reef fish use nearshore seascapes in the future. PMID:25551761

Mangrove habitat use by juvenile reef fish: meta-analysis reveals that tidal regime matters more than biogeographic region.

PubMed

Igulu, Mathias M; Nagelkerken, Ivan; Dorenbosch, Martijn; Grol, Monique G G; Harborne, Alastair R; Kimirei, Ismael A; Mumby, Peter J; Olds, Andrew D; Mgaya, Yunus D

2014-01-01

Identification of critical life-stage habitats is key to successful conservation efforts. Juveniles of some species show great flexibility in habitat use while other species rely heavily on a restricted number of juvenile habitats for protection and food. Considering the rapid degradation of coastal marine habitats worldwide, it is important to evaluate which species are more susceptible to loss of juvenile nursery habitats and how this differs across large biogeographic regions. Here we used a meta-analysis approach to investigate habitat use by juvenile reef fish species in tropical coastal ecosystems across the globe. Densities of juvenile fish species were compared among mangrove, seagrass and coral reef habitats. In the Caribbean, the majority of species showed significantly higher juvenile densities in mangroves as compared to seagrass beds and coral reefs, while for the Indo-Pacific region seagrass beds harbored the highest overall densities. Further analysis indicated that differences in tidal amplitude, irrespective of biogeographic region, appeared to be the major driver for this phenomenon. In addition, juvenile reef fish use of mangroves increased with increasing water salinity. In the Caribbean, species of specific families (e.g. Lutjanidae, Haemulidae) showed a higher reliance on mangroves or seagrass beds as juvenile habitats than other species, whereas in the Indo-Pacific family-specific trends of juvenile habitat utilization were less apparent. The findings of this study highlight the importance of incorporating region-specific tidal inundation regimes into marine spatial conservation planning and ecosystem based management. Furthermore, the significant role of water salinity and tidal access as drivers of mangrove fish habitat use implies that changes in seawater level and rainfall due to climate change may have important effects on how juvenile reef fish use nearshore seascapes in the future.

Lymph node density as a prognostic predictor in patients with betel nut-related oral squamous cell carcinoma.

PubMed

Chang, Wei-Chin; Lin, Chun-Shu; Yang, Cheng-Yu; Lin, Chih-Kung; Chen, Yuan-Wu

2018-04-01

Lymph node metastasis in oral squamous cell carcinoma (OSCC) is a poor prognostic factor. The histopathologic stage (e.g., pN) is used to evaluate the severity of lymph node metastasis; however, the current staging system insufficiently predicts survival and recurrence. We investigated clinical outcomes and lymph node density (LND) in betel nut-chewing individuals. We retrospectively analyzed 389 betel nut-exposed patients with primary OSCC who underwent surgical resection in 2002-2015. The prognostic significance of LND was evaluated by overall survival (OS) and disease-free survival (DFS) using the Kaplan-Meier method. Kaplan-Meier analyses showed that the 5-year OS and DFS rates in all patients were 60.9 and 48.9%, respectively. Multivariate analysis showed that variables independently prognostic for OS were aged population (hazard ratio [HR] = 1.6, 95% confidence interval [95% CI] = 1.1-2.5; P = .025), and cell differentiation classification (HR = 2.4, 95% CI = 1.4-4.2; P = .002). In pathologic N-positive patients, a receiver operating characteristic (ROC) curve for OS was used and indicated the best cutoff of 0.05, and the multivariate analysis showed that LND was an independent predictor of OS (HR = 2.2, 95% CI = 1.3-3.7; P = .004). Lymph node density, at a cutoff of 0.05, was an independent predictor of OS and DFS. OS and DFS underwent multiple analyses, and LND remained significant. The pathologic N stage had no influence in the OS analysis. LND is a more reliable predictor of survival in betel nut-chewing patients for further post operation adjuvant treatment, such as reoperation or adjuvant radiotherapy.

Application of remote sensing analysis and MT method for identification geothermal prospect zone in Mt. Endut

NASA Astrophysics Data System (ADS)

Akbar, A. M.; Permadi, A. N.; Wildan, D.; Sobirin, R.; Supriyanto

2017-07-01

Mount Endut is located at Banten Province, 40 km southward Rangkasbitung City, with geographic UTM position between 9261000-9274000 N and 639000-652000 E. Preliminary survey at Mt. Endut was geological and geochemical survey in 2006, resistivity survey and MT survey in 2007 with 27 measurement point. All survey conducted by Pusat Sumber Daya Geologi (PSDG). According to result of premilinary survey, Mt. Endut is dominated by quartenary volcanic rock produced by Mt. Endut, which breakthrough tertiary sediment layer. NE to SW normal fault produced surface manifestation, namely Cikawah (CKW) hot spring and Handeleum (HDL) hot spring. According to SiO2 and NaK geothermometer, subsurface temperature of Mt Endut is ranging from 162 to 180 °C. Apparent resistivity maps show that thermal manifestation areas coincide with pronounced high anomaly due to resistive intrusion bodies contrast to conductive sedimentary basements. In order to delineate permeability zone, fracture fault density (FFD) analysis from remote sensing image is carry out. FFD analysis from lansdat 7 image shows the area on westward flank of Mt. Endut have high fracture fault density (162-276 m/km2), higher than it's surrounding area and can be assume that area is weak zone and have high permeability. That's structure density anomaly coincide with low resistivity from Magnetotelluric data. Resistivity structure from Magnetotelluric data shows western flank have low permeability layer (14-27 Ohmm) with average thickness 250 m. Below this layer there is layer with higher resistivity (37-100 Ohmm) with ±1000 m depth and interpreted as shallow reservoir. Massive resistif intrusive bodies act controlled the surface manifestation, and act as boundary and bounded the geothermal system in western part of Mt. Endut.

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

Improving the Accuracy of Mapping Urban Vegetation Carbon Density by Combining Shadow Remove, Spectral Unmixing Analysis and Spatial Modeling

NASA Astrophysics Data System (ADS)

Qie, G.; Wang, G.; Wang, M.

2016-12-01

Mixed pixels and shadows due to buildings in urban areas impede accurate estimation and mapping of city vegetation carbon density. In most of previous studies, these factors are often ignored, which thus result in underestimation of city vegetation carbon density. In this study we presented an integrated methodology to improve the accuracy of mapping city vegetation carbon density. Firstly, we applied a linear shadow remove analysis (LSRA) on remotely sensed Landsat 8 images to reduce the shadow effects on carbon estimation. Secondly, we integrated a linear spectral unmixing analysis (LSUA) with a linear stepwise regression (LSR), a logistic model-based stepwise regression (LMSR) and k-Nearest Neighbors (kNN), and utilized and compared the integrated models on shadow-removed images to map vegetation carbon density. This methodology was examined in Shenzhen City of Southeast China. A data set from a total of 175 sample plots measured in 2013 and 2014 was used to train the models. The independent variables statistically significantly contributing to improving the fit of the models to the data and reducing the sum of squared errors were selected from a total of 608 variables derived from different image band combinations and transformations. The vegetation fraction from LSUA was then added into the models as an important independent variable. The estimates obtained were evaluated using a cross-validation method. Our results showed that higher accuracies were obtained from the integrated models compared with the ones using traditional methods which ignore the effects of mixed pixels and shadows. This study indicates that the integrated method has great potential on improving the accuracy of urban vegetation carbon density estimation. Key words: Urban vegetation carbon, shadow, spectral unmixing, spatial modeling, Landsat 8 images

Principal component analysis of the CT density histogram to generate parametric response maps of COPD

NASA Astrophysics Data System (ADS)

Zha, N.; Capaldi, D. P. I.; Pike, D.; McCormack, D. G.; Cunningham, I. A.; Parraga, G.

2015-03-01

Pulmonary x-ray computed tomography (CT) may be used to characterize emphysema and airways disease in patients with chronic obstructive pulmonary disease (COPD). One analysis approach - parametric response mapping (PMR) utilizes registered inspiratory and expiratory CT image volumes and CT-density-histogram thresholds, but there is no consensus regarding the threshold values used, or their clinical meaning. Principal-component-analysis (PCA) of the CT density histogram can be exploited to quantify emphysema using data-driven CT-density-histogram thresholds. Thus, the objective of this proof-of-concept demonstration was to develop a PRM approach using PCA-derived thresholds in COPD patients and ex-smokers without airflow limitation. Methods: Fifteen COPD ex-smokers and 5 normal ex-smokers were evaluated. Thoracic CT images were also acquired at full inspiration and full expiration and these images were non-rigidly co-registered. PCA was performed for the CT density histograms, from which the components with the highest eigenvalues greater than one were summed. Since the values of the principal component curve correlate directly with the variability in the sample, the maximum and minimum points on the curve were used as threshold values for the PCA-adjusted PRM technique. Results: A significant correlation was determined between conventional and PCA-adjusted PRM with 3He MRI apparent diffusion coefficient (p<0.001), with CT RA950 (p<0.0001), as well as with 3He MRI ventilation defect percent, a measurement of both small airways disease (p=0.049 and p=0.06, respectively) and emphysema (p=0.02). Conclusions: PRM generated using PCA thresholds of the CT density histogram showed significant correlations with CT and 3He MRI measurements of emphysema, but not airways disease.

Breast Density and Risk of Breast Cancer in Asian Women: A Meta-analysis of Observational Studies.

PubMed

Bae, Jong-Myon; Kim, Eun Hee

2016-11-01

The established theory that breast density is an independent predictor of breast cancer risk is based on studies targeting white women in the West. More Asian women than Western women have dense breasts, but the incidence of breast cancer is lower among Asian women. This meta-analysis investigated the association between breast density in mammography and breast cancer risk in Asian women. PubMed and Scopus were searched, and the final date of publication was set as December 31, 2015. The effect size in each article was calculated using the interval-collapse method. Summary effect sizes (sESs) and 95% confidence intervals (CIs) were calculated by conducting a meta-analysis applying a random effect model. To investigate the dose-response relationship, random effect dose-response meta-regression (RE-DRMR) was conducted. Six analytical epidemiology studies in total were selected, including one cohort study and five case-control studies. A total of 17 datasets were constructed by type of breast density index and menopausal status. In analyzing the subgroups of premenopausal vs. postmenopausal women, the percent density (PD) index was confirmed to be associated with a significantly elevated risk for breast cancer (sES, 2.21; 95% CI, 1.52 to 3.21; I 2 =50.0%). The RE-DRMR results showed that the risk of breast cancer increased 1.73 times for each 25% increase in PD in postmenopausal women (95% CI, 1.20 to 2.47). In Asian women, breast cancer risk increased with breast density measured using the PD index, regardless of menopausal status. We propose the further development of a breast cancer risk prediction model based on the application of PD in Asian women.

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.

Assembly-history dynamics of a pitcher-plant protozoan community in experimental microcosms.

PubMed

Kadowaki, Kohmei; Inouye, Brian D; Miller, Thomas E

2012-01-01

History drives community assembly through differences both in density (density effects) and in the sequence in which species arrive (sequence effects). Density effects arise from predictable population dynamics, which are free of history, but sequence effects are due to a density-free mechanism, arising solely from the order and timing of immigration events. Few studies have determined how components of immigration history (timing, number of individuals, frequency) alter local dynamics to determine community assembly, beyond addressing when immigration history produces historically contingent assembly. We varied density and sequence effects independently in a two-way factorial design to follow community assembly in a three-species aquatic protozoan community. A superior competitor, Colpoda steinii, mediated alternative community states; early arrival or high introduction density allowed this species to outcompete or suppress the other competitors (Poterioochromonas malhamensis and Eimeriidae gen. sp.). Multivariate analysis showed that density effects caused greater variation in community states, whereas sequence effects altered the mean community composition. A significant interaction between density and sequence effects suggests that we should refine our understanding of priority effects. These results highlight a practical need to understand not only the "ingredients" (species) in ecological communities but their "recipes" as well.

Effects of fiber density and plasma modification of nanofibrous membranes on the adhesion and growth of HaCaT keratinocytes.

PubMed

Bacakova, Marketa; Lopot, Frantisek; Hadraba, Daniel; Varga, Marian; Zaloudkova, Margit; Stranska, Denisa; Suchy, Tomas; Bacakova, Lucie

2015-01-01

It may be possible to regulate the cell colonization of biodegradable polymer nanofibrous membranes by plasma treatment and by the density of the fibers. To test this hypothesis, nanofibrous membranes of different fiber densities were treated by oxygen plasma with a range of plasma power and exposure times. Scanning electron microscopy and mechanical tests showed significant modification of nanofibers after plasma treatment. The intensity of the fiber modification increased with plasma power and exposure time. The exposure time seemed to have a stronger effect on modifying the fiber. The mechanical behavior of the membranes was influenced by the plasma treatment, the fiber density, and their dry or wet state. Plasma treatment increased the membrane stiffness; however, the membranes became more brittle. Wet membranes displayed significantly lower stiffness than dry membranes. X-ray photoelectron spectroscopy (XPS) analysis showed a slight increase in oxygen-containing groups on the membrane surface after plasma treatment. Plasma treatment enhanced the adhesion and growth of HaCaT keratinocytes on nanofibrous membranes. The cells adhered and grew preferentially on membranes of lower fiber densities, probably due to the larger area of void spaces between the fibers. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Momentum transport and nonlocality in heat-flux-driven magnetic reconnection in high-energy-density plasmas.

PubMed

Liu, Chang; Fox, William; Bhattacharjee, Amitava; Thomas, Alexander G R; Joglekar, Archis S

2017-10-01

Recent theory has demonstrated a novel physics regime for magnetic reconnection in high-energy-density plasmas where the magnetic field is advected by heat flux via the Nernst effect. Here we elucidate the physics of the electron dissipation layer in this regime. Through fully kinetic simulation and a generalized Ohm's law derived from first principles, we show that momentum transport due to a nonlocal effect, the heat-flux-viscosity, provides the dissipation mechanism for magnetic reconnection. Scaling analysis, and simulations show that the reconnection process comprises a magnetic field compression stage and quasisteady reconnection stage, and the characteristic width of the current sheet in this regime is several electron mean-free paths. These results show the important interplay between nonlocal transport effects and generation of anisotropic components to the distribution function.

Recurrence Density Enhanced Complex Networks for Nonlinear Time Series Analysis

NASA Astrophysics Data System (ADS)

Costa, Diego G. De B.; Reis, Barbara M. Da F.; Zou, Yong; Quiles, Marcos G.; Macau, Elbert E. N.

We introduce a new method, which is entitled Recurrence Density Enhanced Complex Network (RDE-CN), to properly analyze nonlinear time series. Our method first transforms a recurrence plot into a figure of a reduced number of points yet preserving the main and fundamental recurrence properties of the original plot. This resulting figure is then reinterpreted as a complex network, which is further characterized by network statistical measures. We illustrate the computational power of RDE-CN approach by time series by both the logistic map and experimental fluid flows, which show that our method distinguishes different dynamics sufficiently well as the traditional recurrence analysis. Therefore, the proposed methodology characterizes the recurrence matrix adequately, while using a reduced set of points from the original recurrence plots.

Analysis of the spatial distribution of dengue cases in the city of Rio de Janeiro, 2011 and 2012

PubMed Central

Carvalho, Silvia; Magalhães, Mônica de Avelar Figueiredo Mafra; Medronho, Roberto de Andrade

2017-01-01

ABSTRACT OBJECTIVE Analyze the spatial distribution of classical dengue and severe dengue cases in the city of Rio de Janeiro. METHODS Exploratory study, considering cases of classical dengue and severe dengue with laboratory confirmation of the infection in the city of Rio de Janeiro during the years 2011/2012. The georeferencing technique was applied for the cases notified in the Notification Increase Information System in the period of 2011 and 2012. For this process, the fields “street” and “number” were used. The ArcGis10 program’s Geocoding tool’s automatic process was performed. The spatial analysis was done through the kernel density estimator. RESULTS Kernel density pointed out hotspots for classic dengue that did not coincide geographically with severe dengue and were in or near favelas. The kernel ratio did not show a notable change in the spatial distribution pattern observed in the kernel density analysis. The georeferencing process showed a loss of 41% of classic dengue registries and 17% of severe dengue registries due to the address in the Notification Increase Information System form. CONCLUSIONS The hotspots near the favelas suggest that the social vulnerability of these localities can be an influencing factor for the occurrence of this aggravation since there is a deficiency of the supply and access to essential goods and services for the population. To reduce this vulnerability, interventions must be related to macroeconomic policies. PMID:28832752

The effects of low environmental cadmium exposure on bone density

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

Trzcinka-Ochocka, M., E-mail: ochocka@imp.lodz.pl; Jakubowski, M.; Szymczak, W.

2010-04-15

Recent epidemiological data indicate that low environmental exposure to cadmium, as shown by cadmium body burden (Cd-U), is associated with renal dysfunction as well as an increased risk of cadmium-induced bone disorders. The present study was designed to assess the effects of low environmental cadmium exposure, at the level sufficient to induce kidney damage, on bone metabolism and mineral density (BMD). The project was conducted in the area contaminated with cadmium, nearby a zinc smelter located in the region of Poland where heavy industry prevails. The study population comprised 170 women (mean age=39.7; 18-70 years) and 100 men (mean age=31.9;more » 18-76 years). Urinary and blood cadmium and the markers of renal tubular dysfunction ({beta}{sub 2}M-U RBP, NAG), glomerular dysfunction (Alb-U and {beta}{sub 2}M-S) and bone metabolism markers (BAP-S, CTX-S) as well as forearm BMD, were measured. The results of this study based on simple dose-effect analysis showed the relationship between increasing cadmium concentrations and an increased excretion of renal dysfunction markers and decreasing bone density. However, the results of the multivariate analysis did not indicate the association between exposure to cadmium and decrease in bone density. They showed that the most important factors that have impact on bone density are body weight and age in the female subjects and body weight and calcium excretion in males. Our investigation revealed that the excretion of low molecular weight proteins occurred at a lower level of cadmium exposure than the possible loss of bone mass. It seems that renal tubular markers are the most sensitive and significant indicators of early health effects of cadmium intoxication in the general population. The correlation of urinary cadmium concentration with markers of kidney dysfunction was observed in the absence of significant correlations with bone effects. Our findings did not indicate any effects of environmental cadmium exposure on bone density.« less

Methods for passivating silicon devices at low temperature to achieve low interface state density and low recombination velocity while preserving carrier lifetime

DOEpatents

Chen, Zhizhang; Rohatgi, Ajeet

1995-01-01

A new process has been developed to achieve a very low SiO.sub.x /Si interface state density D.sub.it, low recombination velocity S (<2 cm/s), and high effective carrier lifetime T.sub.eff (>5 ms) for oxides deposited on silicon substrates at low temperature. The technique involves direct plasma-enhanced chemical vapor deposition (PECVD), with appropriate growth conditions, followed by a photo-assisted rapid thermal annealing (RTA) process. Approximately 500-A-thick SiO.sub.x layers are deposited on Si by PECVD at 250.degree. C. with 0.02 W/cm.sup.-2 rf power, then covered with SiN or an evaporated thin aluminum layer, and subjected to a photo-assisted anneal in forming gas ambient at 350.degree. C., resulting in an interface state density D.sub.it in the range of about 1-4.times.10.sup.10 cm.sup.-2 eV.sup.-1, which sets a record for the lowest interface state density D.sub.it for PECVD oxides fabricated to date. Detailed analysis shows that the PECVD deposition conditions, photo-assisted anneal, forming gas ambient, and the presence of an aluminum layer on top of the oxides during the anneal, all contributed to this low value of interface state density D.sub.it. Detailed metal-oxide semiconductor analysis and model calculations show that such a low recombination velocity S is the result of moderately high positive oxide charge (5.times.10.sup.11 -1.times.10.sup.12 cm.sup.-2) and relatively low midgap interface state density (1.times.10.sup.10 -4.times.10.sup.10 cm.sup.-2 eV.sup.-1). Photo-assisted anneal was found to be superior to furnace annealing, and a forming gas ambient was better than a nitrogen ambient for achieving a very low surface recombination velocity S.

Spinal Implant Density and Postoperative Lumbar Lordosis as Predictors for the Development of Proximal Junctional Kyphosis in Adult Spinal Deformity.

PubMed

McClendon, Jamal; Smith, Timothy R; Sugrue, Patrick A; Thompson, Sara E; O'Shaughnessy, Brian A; Koski, Tyler R

2016-11-01

To evaluate spinal implant density and proximal junctional kyphosis (PJK) in adult spinal deformity (ASD). Consecutive patients with ASD receiving ≥5 level fusions were retrospectively analyzed between 2007 and 2010. ASD, elective fusions, minimum 2-year follow-up. age <18 years, neuromuscular or congenital scoliosis, cervical or cervicothoracic fusions, nonelective conditions (infection, tumor, trauma). Instrumented fusions were classified by the Scoliosis Research Society-Schwab ASD classification. Statistical analysis consisted of descriptives (measures of central tendency, dispersion, frequencies), independent Student t tests, χ 2 , analysis of variance, and logistic regression to determine association of implant density [(number of screws + number of hooks)/surgical levels of fusion] and PJK. Mean and median follow-up was 2.8 and 2.7 years, respectively. Eighty-three patients (17 male, 66 female) with a mean age of 59.7 years (standard deviation, 10.3) were analyzed. Mean body mass index (BMI) was 29.5 kg/m 2 (range, 18-56 kg/m 2 ) with mean preoperative Oswestry Disability Index of 48.67 (range, 6-86) and mean preoperative sagittal vertical axis of 8.42. The mean levels fused were 9.95 where 54 surgeries had interbody fusion. PJK prevalence was 21.7%, and pseudoarthrosis was 19.3%. Mean postoperative Oswestry Disability Index was 27.4 (range, 0-74). Independent Student t tests showed that PJK was not significant for age, gender, BMI, rod type, mean postoperative sagittal vertical axis, or Scoliosis Research Society-Schwab ASD classification; but iliac fixation approached significance (P = 0.077). Implant density and postoperative lumbar lordosis (LL) were predictors for PJK (P = 0.018 and 0.045, respectively). Controlling for age, BMI, and gender, postoperative LL (not implant density) continued to show significance in multivariate logistic regression model. PJK, although influenced by a multitude of factors, may be statistically related to implant density and LL. Copyright © 2016. Published by Elsevier Inc.

[Endothelial keratopathy in pseudoexfoliation syndrome: quantitative and qualitative morphometry using automated video image analysis].

PubMed

Seitz, B; Müller, E E; Langenbucher, A; Kus, M M; Naumann, G O

1995-09-01

This prospective study intended to quantify and classify morphological changes of the corneal endothelium in pseudoexfoliation syndrome (PSX) after having tested reproducibility and validity of a new automated technique for analysing corneal endothelium. We used a contact specular microscope combined with a video camera (Tomey EM-1000) and a computer (IBM compatible PC, 486DX33) with suitable software (Tomey EM-1100, version 0.94). Video images of corneal endothelium (area: 0.312 mm2) are passed directly into the computer input by means of a frame grabber and are automatically processed. Missing or falsely recognized cell borders are corrected using the mouse. We examined 85 eyes with PSX and 33 healthy control eyes. At first, retest-stability and validity of the cell density measurements were assessed in the PSX-eyes. A qualitative analysis of the corneal endothelium followed. The cell density measurements showed a high retest-stability (reliability coefficient r = 0.974). The values of the automated method (2040 +/- 285 cells/mm2) and those of manual cell counting (2041 +/- 275 cells/mm2) did not differ significantly (p = 0.441). The mean difference was 3.1 +/- 2.4%. Comparing the 85 PSX-eyes (2052 +/- 264 cells/mm2) to the 33 control eyes (2372 +/- 276 cells/mm2), there was a significant reduction of cell density (p < 0.001). The cell density of the 69 PSX-eyes with glaucoma (2014 +/- 254 cells/mm2) was significantly lower than that of the 16 PSX-eyes without glaucoma (2214 +/- 251 cells/mm2) (p = 0.008). Eighty-five percent of the 85 PSX-eyes showed polymegalism, 77% pleomorphism; 68% had white deposits and 42% guttae. White deposits and guttae were significantly more frequent and more intensive in PSX-eyes than in control eyes. PSX-eyes with and those without glaucoma showed no significant differences concerning the four qualitative parameters. The automated method for analysing corneal endothelium quickly provides reproducible and valid results using the correction mode of the software. Semiquantitative analysis of qualitative parameters permits a more differentiated assessment of keratopathy in pseudoexfoliation syndrome than does mere consideration of endothelial cell density. Both evaluations are recommended to assess the risk of a diffuse endothelial decompensation before intraocular surgery.

Spatial Variations of Turbulent Properties of Neutral Hydrogen Gas in the Small Magellanic Cloud Using Structure-function Analysis

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

Nestingen-Palm, David; Stanimirović, Snežana; González-Casanova, Diego F.

2017-08-10

We investigate spatial variations of turbulent properties in the Small Magellanic Cloud (SMC) by using neutral hydrogen (H i) observations. With the goal of testing the importance of stellar feedback on H i turbulence, we define central and outer SMC regions based on the star formation rate (SFR) surface density, as well as the H i integrated intensity. We use the structure function and the velocity channel analysis to calculate the power-law index ( γ ) for both underlying density and velocity fields in these regions. In all cases, our results show essentially no difference in γ between the centralmore » and outer regions. This suggests that H i turbulent properties are surprisingly homogeneous across the SMC when probed at a resolution of 30 pc. Contrary to recent suggestions from numerical simulations, we do not find a significant change in γ due to stellar feedback as traced by the SFR surface density. This could be due to the stellar feedback being widespread over the whole of the SMC, but more likely due to a large-scale gravitational driving of turbulence. We show that the lack of difference between central and outer SMC regions cannot be explained by the high optical depth H I.« less

A Rocket Investigation of Mesospheric Eddy Diffusion Effects on Airglow and Oxygen Chemistry

NASA Technical Reports Server (NTRS)

Ulwick, James C.

2001-01-01

A Terrier Orion rocket was launched at 0750 Z on 02/25/98 about seven minutes after the Clemson University chemical release rocket. Measurements made of the electron density by a dc probe calibrated by a capacitance probe showed several layers of electron density on a rocket ascent in the altitude range from 90 to 110 km. Rocket descent results showed several but not all of the ascent structure. From power spectral analysis of the measured electron densities, turbulent parameters are derived Measurements were made on rocket ascent and descent by an infrared radiometer of the OH Meinel (3-1) band and O2 singlet delta emissions. Profiles of the emissions are presented and discussed on both rocket ascent and descent an enhancement of the OH emission monitored by the OH radiometer was observed above 90 km. The glow was not defected by the O2 radiometer and was significantly reduced on rocket descent. Using these data and a mechanistic analysis, a profile proportional to atomic oxygen is obtained. This profile is compared to one from the ATOX probe on the rocket. A one-dimensional (1-D) photochemical model that solves the time-dependent continuity equations is used with the rocket data to investigate the odd-oxygen concentration in the near equatorial mesosphere.

Generating a Multiphase Equation of State with Swarm Intelligence

NASA Astrophysics Data System (ADS)

Cox, Geoffrey

2017-06-01

Hydrocode calculations require knowledge of the variation of pressure of a material with density and temperature, which is given by the equation of state. An accurate model needs to account for discontinuities in energy, density and properties of a material across a phase boundary. When generating a multiphase equation of state the modeller attempts to balance the agreement between the available data for compression, expansion and phase boundary location. However, this can prove difficult because minor adjustments in the equation of state for a single phase can have a large impact on the overall phase diagram. Recently, Cox and Christie described a method for combining statistical-mechanics-based condensed matter physics models with a stochastic analysis technique called particle swarm optimisation. The models produced show good agreement with experiment over a wide range of pressure-temperature space. This talk details the general implementation of this technique, shows example results, and describes the types of analysis that can be performed with this method.

MicroCT Analysis of Micro-Nano Titanium Implant Surface on the Osseointegration.

PubMed

Ban, Jaesam; Kang, Seongsoo; Kim, Jihyun; Lee, Kwangmin; Hyunpil, Lim; Vang, Mongsook; Yang, Hongso; Oh, Gyejeong; Kim, Hyunseung; Hwang, Gabwoon; Jung, Yongho; Lee, Kyungku; Park, Sangwon; Yunl, Kwidug

2015-01-01

This study was to investigate the effects of micro-nano titanium implant surface on the osseointegration. A total of 36 screw-shaped implants were used. The implant surfaces were classified into 3 groups (n = 12): machined surface (M group), nanosurface which is nanotube formation on the machined surface (MA group) and nano-micro surface which is nanotube formation on the RBM surface (RA group). Anodic oxidation was performed at a 20 V for 10 min with 1 M H3PO4 and 1.5 wt% HF solutions. The implants were installed on the humerus on 6 beagles. After 4 and 12 weeks, the morphometric analysis with micro CT (skyscan 1172, SKYSCAN, Antwerpen, Belgium) was done. The data were statistically analyzed with two-way ANOVA. Bone mineral density and bone volume were significantly increased depending on time. RA group showed the highest bone mineral density and bone volume at 4 weeks and 12 weeks significantly. It indicated that nano-micro titanium implant surface showed faster and more mature osseointegration.

Lymphocyte density determined by computational pathology validated as a predictor of response to neoadjuvant chemotherapy in breast cancer: secondary analysis of the ARTemis trial.

PubMed

Ali, H R; Dariush, A; Thomas, J; Provenzano, E; Dunn, J; Hiller, L; Vallier, A-L; Abraham, J; Piper, T; Bartlett, J M S; Cameron, D A; Hayward, L; Brenton, J D; Pharoah, P D P; Irwin, M J; Walton, N A; Earl, H M; Caldas, C

2017-08-01

We have previously shown lymphocyte density, measured using computational pathology, is associated with pathological complete response (pCR) in breast cancer. The clinical validity of this finding in independent studies, among patients receiving different chemotherapy, is unknown. The ARTemis trial randomly assigned 800 women with early stage breast cancer between May 2009 and January 2013 to three cycles of docetaxel, followed by three cycles of fluorouracil, epirubicin and cyclophosphamide once every 21 days with or without four cycles of bevacizumab. The primary endpoint was pCR (absence of invasive cancer in the breast and lymph nodes). We quantified lymphocyte density within haematoxylin and eosin (H&E) whole slide images using our previously described computational pathology approach: for every detected lymphocyte the average distance to the nearest 50 lymphocytes was calculated and the density derived from this statistic. We analyzed both pre-treatment biopsies and post-treatment surgical samples of the tumour bed. Of the 781 patients originally included in the primary endpoint analysis of the trial, 609 (78%) were included for baseline lymphocyte density analyses and a subset of 383 (49% of 781) for analyses of change in lymphocyte density. The main reason for loss of patients was the availability of digitized whole slide images. Pre-treatment lymphocyte density modelled as a continuous variable was associated with pCR on univariate analysis (odds ratio [OR], 2.92; 95% CI, 1.78-4.85; P < 0.001) and after adjustment for clinical covariates (OR, 2.13; 95% CI, 1.24-3.67; P = 0.006). Increased pre- to post-treatment lymphocyte density showed an independent inverse association with pCR (adjusted OR, 0.1; 95% CI, 0.033-0.31; P < 0.001). Lymphocyte density in pre-treatment biopsies was validated as an independent predictor of pCR in breast cancer. Computational pathology is emerging as a viable and objective means of identifying predictive biomarkers for cancer patients. NCT01093235. © The Author 2017. Published by Oxford University Press on behalf of the European Society for Medical Oncology.

Speed-of-light limitations in passive linear media

NASA Astrophysics Data System (ADS)

Welters, Aaron; Avniel, Yehuda; Johnson, Steven G.

2014-08-01

We prove that well-known speed-of-light restrictions on electromagnetic energy velocity can be extended to a new level of generality, encompassing even nonlocal chiral media in periodic geometries, while at the same time weakening the underlying assumptions to only passivity and linearity of the medium (either with a transparency window or with dissipation). As was also shown by other authors under more limiting assumptions, passivity alone is sufficient to guarantee causality and positivity of the energy density (with no thermodynamic assumptions). Our proof is general enough to include a very broad range of material properties, including anisotropy, bianisotropy (chirality), nonlocality, dispersion, periodicity, and even delta functions or similar generalized functions. We also show that the "dynamical energy density" used by some previous authors in dissipative media reduces to the standard Brillouin formula for dispersive energy density in a transparency window. The results in this paper are proved by exploiting deep results from linear-response theory, harmonic analysis, and functional analysis that had previously not been brought together in the context of electrodynamics.

Experimental and DFT studies of (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline: electronic and vibrational properties.

PubMed

Sun, Wenqi; Yuan, Guozan; Liu, Jingxin; Ma, Li; Liu, Chengbu

2013-04-01

The title molecule (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline (DPEQ) was synthesized and characterized by FT-IR, UV-vis, NMR spectroscopy. The molecular geometry, vibrational frequencies and gauge independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the compound in the ground state have been calculated by using the density functional theory (DFT) method. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. The calculated results indicate that the theoretical vibrational frequencies, 1H and 13C NMR chemical shift values show good agreement with experimental data. The electronic properties like UV-vis spectral analysis and HOMO-LUMO analysis of DPEQ have been reported and compared with experimental data. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with molecular electrostatic potential (MEP). Copyright © 2013 Elsevier B.V. All rights reserved.

Experimental and DFT studies of (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline: Electronic and vibrational properties

NASA Astrophysics Data System (ADS)

Sun, Wenqi; Yuan, Guozan; Liu, Jingxin; Ma, Li; Liu, Chengbu

2013-04-01

The title molecule (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline (DPEQ) was synthesized and characterized by FT-IR, UV-vis, NMR spectroscopy. The molecular geometry, vibrational frequencies and gauge independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the compound in the ground state have been calculated by using the density functional theory (DFT) method. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. The calculated results indicate that the theoretical vibrational frequencies, 1H and 13C NMR chemical shift values show good agreement with experimental data. The electronic properties like UV-vis spectral analysis and HOMO-LUMO analysis of DPEQ have been reported and compared with experimental data. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with molecular electrostatic potential (MEP).

[Periodontal treatment for cardiovascular risk factors: a systematic review].

PubMed

Deng, Linkai; Li, Chunjie; Li, Qian; Zhang, Yukui; Zhao, Hongwei

2013-10-01

To evaluate the efficacy of periodontal treatment for the management of cardiovascular risk factors. Eligible studies in Cochrane Controlled Trials Register/CENTRAL, PubMed, EMBASE, and China Biology Medicine disc (CBMdisc) were searched until October 13, 2011. References of the included studies were hand searched. Two reviewers assessed the risk of bias and extracted the data of the included studies in duplicate. Meta-analysis was conducted with Revman 5.1. Six randomized controlled trials involving 682 participants were included. One case had low risk of bias, another one had moderate risk of bias, and the remaining four had high risk of bias. Meta-analysis showed that periodontal treatment has no significant effect on C-reactive protein, total cholesterol, low-density lipoprotein cholesterol, and triglycerides (P > 0.05). However, the treatment had a significant effect on high-density lipoprotein cholesterol [MD = 0.05, 95% CI (0.00, 0.09), P = 0.04]. Periodontal treatment has good effects on controlling high-density lipoprotein cholesterol although more randomized controlled trials must be conducted to verify its effectiveness.

Propositional idea density in older men's written language: findings from the HIMS study using computerised analysis.

PubMed

Spencer, Elizabeth; Ferguson, Alison; Craig, Hugh; Colyvas, Kim; Hankey, Graeme J; Flicker, Leon

2015-02-01

Decline in linguistic function has been associated with decline in cognitive function in previous research. This research investigated the informativeness of written language samples of Australian men from the Health in Men's Study (HIMS) aged from 76 to 93 years using the Computerised Propositional Idea Density Rater (CPIDR 5.1). In total, 60,255 words in 1147 comments were analysed using a linear-mixed model for statistical analysis. Results indicated no relationship with education level (p = 0.79). Participants for whom English was not their first learnt language showed Propositional Idea Density (PD) scores slightly lower (0.018 per 1 word). Mean PD per 1 word for those for whom English was their first language for comments below 60 words was 0.494 and above 60 words 0.526. Text length was found to have an effect (p = <0.0001). The mean PD was higher than previously reported for men and lower than previously reported for a similar cohort for Australian women.

Decreased consumption of sugar-sweetened beverages improved selected biomarkers of chronic disease risk among US adults: 1999 to 2010.

PubMed

Hert, Kerrie A; Fisk, Paul S; Rhee, Yeong S; Brunt, Ardith R

2014-01-01

Consumption of sugar-sweetened beverages (SSBs) increased greatly from the late 1970s to the early part of this decade. Although recent data show that consumption of SSB may now be declining, consumption levels still remain much higher than recommended. Using data from the National Health and Nutrition Examination Survey, we assessed trends in intakes of SSB and levels of chronic disease biomarkers from 1999 to 2010 and examined the associations of SSB intake and biomarkers of chronic disease risk. We hypothesized that SSB intake will decrease and biomarkers of chronic disease risk will improve, therefore indicating that high intake of SSB is associated with greater chronic disease risk. Univariate analysis showed that from 1999 to 2010, SSB consumption decreased (P for trend = .0026), high-density lipoprotein increased (P for trend < .0001), low-density lipoprotein decreased (P for trend = .0007), and C-reactive protein decreased (P for trend = .0096). Using multivariate analysis, we showed that higher intakes of SSB were associated with lower high-density lipoprotein (P for trend < .0001), in an unadjusted model and all models with increasing numbers of covariates, and higher C-reactive protein (P for trend < .05), in an unadjusted model and in models with age, race/ethnicity, sex, education level, and poverty income ratio adjustments. We conclude that SSB consumption is associated with biomarkers of chronic disease risk, independent of demographic and lifestyle factors. © 2014.

Surface regulated arsenenes as Dirac materials: From density functional calculations

NASA Astrophysics Data System (ADS)

Yuan, Junhui; Xie, Qingxing; Yu, Niannian; Wang, Jiafu

2017-02-01

Using first principle calculations based on density functional theory (DFT), we have systematically investigated the structure stability and electronic properties of chemically decorated arsenenes, AsX (X = CN, NC, NCO, NCS and NCSe). Phonon dispersion and formation energy analysis reveal that all the five chemically decorated buckled arsenenes are energetically favorable and could be synthesized. Our study shows that wide-bandgap arsenene would turn into Dirac materials when functionalized by -X (X = CN, NC, NCO, NCS and NCSe) groups, rendering new promises in next generation high-performance electronic devices.

Structure Analysis of Jungle-Gym-Type Gels by Brownian Dynamics Simulation

NASA Astrophysics Data System (ADS)

Ohta, Noriyoshi; Ono, Kohki; Takasu, Masako; Furukawa, Hidemitsu

2008-02-01

We investigated the structure and the formation process of two kinds of gels by Brownian dynamics simulation. The effect of flexibility of main chain oligomer was studied. From our results, hard gel with rigid main chain forms more homogeneous network structure than soft gel with flexible main chain. In soft gel, many small loops are formed, and clusters tend to shrink. This heterogeneous network structure may be caused by microgels. In the low density case, soft gel shows more heterogeneity than the high density case.

X-Ray Wind Tomography of IGR J17252-3616

NASA Astrophysics Data System (ADS)

Manousakis, Antonios; Walter, Roland

2010-07-01

IGR J17252-3616, a highly absorbed High Mass X-ray Binary (HMXB) with Hydrogen column density NH~(2-4)×1023 cm-2, has been observed with XMM-Newton for about one month. Observations were scheduled in order to cover the orbital-phase space as much as possible. IGR J17252-3616 shows a varying column density NH and Fe Kα line when fit with simple phenomenological models. A refined orbital solution can be derived. Spectral timing analysis allows derivation of the wind properties of the massive star.

Influence of reagents mixture density on the radiation-thermal synthesis of lithium-zinc ferrites

NASA Astrophysics Data System (ADS)

Surzhikov, A. P.; Lysenko, E. N.; Vlasov, V. A.; Malyshev, A. V.; Korobeynikov, M. V.; Mikhailenko, M. A.

2017-01-01

Influence of Li2CO3-ZnO-Fe2O3 powder reagents mixture density on the synthesis efficiency of lithium-zinc ferrites in the conditions of thermal heating or pulsed electron beam heating was studied by X-Ray diffraction and magnetization analysis. The results showed that the including a compaction of powder reagents mixture in ferrite synthesis leads to an increase in concentration of the spinel phase and decrease in initial components content in lithium-substituted ferrites synthesized by thermal or radiation-thermal heating.

Multi-level multi-criteria analysis of alternative fuels for waste collection vehicles in the United States.

PubMed

Maimoun, Mousa; Madani, Kaveh; Reinhart, Debra

2016-04-15

Historically, the U.S. waste collection fleet was dominated by diesel-fueled waste collection vehicles (WCVs); the growing need for sustainable waste collection has urged decision makers to incorporate economically efficient alternative fuels, while mitigating environmental impacts. The pros and cons of alternative fuels complicate the decisions making process, calling for a comprehensive study that assesses the multiple factors involved. Multi-criteria decision analysis (MCDA) methods allow decision makers to select the best alternatives with respect to selection criteria. In this study, two MCDA methods, Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Simple Additive Weighting (SAW), were used to rank fuel alternatives for the U.S. waste collection industry with respect to a multi-level environmental and financial decision matrix. The environmental criteria consisted of life-cycle emissions, tail-pipe emissions, water footprint (WFP), and power density, while the financial criteria comprised of vehicle cost, fuel price, fuel price stability, and fueling station availability. The overall analysis showed that conventional diesel is still the best option, followed by hydraulic-hybrid WCVs, landfill gas (LFG) sourced natural gas, fossil natural gas, and biodiesel. The elimination of the WFP and power density criteria from the environmental criteria ranked biodiesel 100 (BD100) as an environmentally better alternative compared to other fossil fuels (diesel and natural gas). This result showed that considering the WFP and power density as environmental criteria can make a difference in the decision process. The elimination of the fueling station and fuel price stability criteria from the decision matrix ranked fossil natural gas second after LFG-sourced natural gas. This scenario was found to represent the status quo of the waste collection industry. A sensitivity analysis for the status quo scenario showed the overall ranking of diesel and fossil natural gas to be more sensitive to changing fuel prices as compared to other alternatives. Copyright © 2016 Elsevier B.V. All rights reserved.

Spatial and Temporal Analysis of Eruption Locations, Compositions, and Styles in Northern Harrat Rahat, Kingdom of Saudi Arabia

NASA Astrophysics Data System (ADS)

Dietterich, H. R.; Stelten, M. E.; Downs, D. T.; Champion, D. E.

2017-12-01

Harrat Rahat is a predominantly mafic, 20,000 km2 volcanic field in western Saudi Arabia with an elongate volcanic axis extending 310 km north-south. Prior mapping suggests that the youngest eruptions were concentrated in northernmost Harrat Rahat, where our new geologic mapping and geochronology reveal >300 eruptive vents with ages ranging from 1.2 Ma to a historic eruption in 1256 CE. Eruption compositions and styles vary spatially and temporally within the volcanic field, where extensive alkali basaltic lavas dominate, but more evolved compositions erupted episodically as clusters of trachytic domes and small-volume pyroclastic flows. Analysis of vent locations, compositions, and eruption styles shows the evolution of the volcanic field and allows assessment of the spatio-temporal probabilities of vent opening and eruption styles. We link individual vents and fissures to eruptions and their deposits using field relations, petrography, geochemistry, paleomagnetism, and 40Ar/39Ar and 36Cl geochronology. Eruption volumes and deposit extents are derived from geologic mapping and topographic analysis. Spatial density analysis with kernel density estimation captures vent densities of up to 0.2 %/km2 along the north-south running volcanic axis, decaying quickly away to the east but reaching a second, lower high along a secondary axis to the west. Temporal trends show slight younging of mafic eruption ages to the north in the past 300 ka, as well as clustered eruptions of trachytes over the past 150 ka. Vent locations, timing, and composition are integrated through spatial probability weighted by eruption age for each compositional range to produce spatio-temporal models of vent opening probability. These show that the next mafic eruption is most probable within the north end of the main (eastern) volcanic axis, whereas more evolved compositions are most likely to erupt within the trachytic centers further to the south. These vent opening probabilities, combined with corresponding eruption properties, can be used as the basis for lava flow and tephra fall hazard maps.

Using Muons to Image the Subsurface.

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

Bonal, Nedra; Cashion, Avery Ted; Cieslewski, Grzegorz

Muons are subatomic particles that can penetrate the earth 's crust several kilometers and may be useful for subsurface characterization . The absorption rate of muons depends on the density of the materials through which they pass. Muons are more sensitive to density variation than other phenomena, including gravity, making them beneficial for subsurface investigation . Measurements of muon flux rate at differing directions provide density variations of the materials between the muon source (cosmic rays and neutrino interactions) and the detector, much like a CAT scan. Currently, muon tomography can resolve features to the sub-meter scale. This work consistsmore » of three parts to address the use of muons for subsurface characterization : 1) assess the use of muon scattering for estimating density differences of common rock types, 2 ) using muon flux to detect a void in rock, 3) measure muon direction by designing a new detector. Results from this project lay the groundwork for future directions in this field. Low-density objects can be detected by muons even when enclosed in high-density material like lead, and even small changes in density (e.g. changes due to fracturing of material) can be detected. Rock density has a linear relationship with muon scattering density per rock volume when this ratio is greater than 0.10 . Limitations on using muon scattering to assess density changes among common rock types have been identified. However, other analysis methods may show improved results for these relatively low density materials. Simulations show that muons can be used to image void space (e.g. tunnels) within rock but experimental results have been ambiguous. Improvements are suggested to improve imaging voids such as tunnels through rocks. Finally, a muon detector has been designed and tested to measure muon direction, which will improve signal-to-noise ratio and help address fundamental questions about the source of upgoing muons .« less

Neurobiological changes of schizotypy: evidence from both volume-based morphometric analysis and resting-state functional connectivity.

PubMed

Wang, Yi; Yan, Chao; Yin, Da-zhi; Fan, Ming-xia; Cheung, Eric F C; Pantelis, Christos; Chan, Raymond C K

2015-03-01

The current study sought to examine the underlying brain changes in individuals with high schizotypy by integrating networks derived from brain structural and functional imaging. Individuals with high schizotypy (n = 35) and low schizotypy (n = 34) controls were screened using the Schizotypal Personality Questionnaire and underwent brain structural and resting-state functional magnetic resonance imaging on a 3T scanner. Voxel-based morphometric analysis and graph theory-based functional network analysis were conducted. Individuals with high schizotypy showed reduced gray matter (GM) density in the insula and the dorsolateral prefrontal gyrus. The graph theoretical analysis showed that individuals with high schizotypy showed similar global properties in their functional networks as low schizotypy individuals. Several hubs of the functional network were identified in both groups, including the insula, the lingual gyrus, the postcentral gyrus, and the rolandic operculum. More hubs in the frontal lobe and fewer hubs in the occipital lobe were identified in individuals with high schizotypy. By comparing the functional connectivity between clusters with abnormal GM density and the whole brain, individuals with high schizotypy showed weaker functional connectivity between the left insula and the putamen, but stronger connectivity between the cerebellum and the medial frontal gyrus. Taken together, our findings suggest that individuals with high schizotypy present changes in terms of GM and resting-state functional connectivity, especially in the frontal lobe. © 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.

An observational study of the nightside ionospheres of Mars and Venus with radio occultation methods

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

Zhang, M.H.G.; Luhmann, J.G.; Kliore, A.J.

1990-10-01

An analysis of Mars and Venus nightside electron density profiles obtained with radio occultation methods shows how the nightside ionospheres of both planets vary with solar zenith angle. From previous studies it is known that the dayside peak electron densities at Mars and Venus show a basic similarity in that they both exhibit Chapman layer-like behavior. In contrast, the peak altitudes at mars behave like an ideal Chapman layer on the dayside, whereas the altitude of the peak at Venus is fairly constant up to the terminator. The effect of major dust storms can also be seen in the peakmore » altitudes at Mars. All Venus nightside electron density profiles show a distinct main peak for both solar minimum and maximum, whereas many profiles from the nightside of Mars do not show any peak at all. This suggests that the electron density in the Mars nightside ionosphere is frequently too low to be detected by radio occultation. On the Pioneer Venus orbiter, disappearing ionospheres were observed near solar maximum in the in-situ data when the solar wind dynamic pressure was exceptionally high. This condition occurs because the high solar wind dynamic pressure decreases the altitude of the ionopause near the terminator below {approximately}250 km, thus reducing the normal nightward transport of dayside ionospheric plasma. On the basis of the Venus observations, one might predict that if a positive correlation of nightside peak density with dynamic pressure was found, it could mean that transport from the dayside is the only significant source for the nightside ionosphere of Mars. The lack of a correlation would imply that the precipitation source at Mars is quite variable.« less

Whole brain analysis of postmortem density changes of grey and white matter on computed tomography by statistical parametric mapping.

PubMed

Nishiyama, Yuichi; Kanayama, Hidekazu; Mori, Hiroshi; Tada, Keiji; Yamamoto, Yasushi; Katsube, Takashi; Takeshita, Haruo; Kawakami, Kazunori; Kitagaki, Hajime

2017-06-01

This study examined the usefulness of statistical parametric mapping (SPM) for investigating postmortem changes on brain computed tomography (CT). This retrospective study included 128 patients (23 - 100 years old) without cerebral abnormalities who underwent unenhanced brain CT before and after death. The antemortem CT (AMCT) scans and postmortem CT (PMCT) scans were spatially normalized using our original brain CT template, and postmortem changes of CT values (in Hounsfield units; HU) were analysed by the SPM technique. Compared with AMCT scans, 58.6 % and 98.4 % of PMCT scans showed loss of the cerebral sulci and an unclear grey matter (GM)-white matter (WM) interface, respectively. SPM analysis revealed a significant decrease in cortical GM density within 70 min after death on PMCT scans, suggesting cytotoxic brain oedema. Furthermore, there was a significant increase in the density of the WM, lenticular nucleus and thalamus more than 120 min after death. The SPM technique demonstrated typical postmortem changes on brain CT scans, and revealed that the unclear GM-WM interface on early PMCT scans is caused by a rapid decrease in cortical GM density combined with a delayed increase in WM density. SPM may be useful for assessment of whole brain postmortem changes. • The original brain CT template achieved successful normalization of brain morphology. • Postmortem changes in the brain were independent of sex. • Cortical GM density decreased rapidly after death. • WM and deep GM densities increased following cortical GM density change. • SPM could be useful for assessment of whole brain postmortem changes.

[Bone mineral density in overweight and obese adolescents].

PubMed

Cobayashi, Fernanda; Lopes, Luiz A; Taddei, José Augusto de A C

2005-01-01

To study bone density as a concomitant factor for obesity in post-pubertal adolescents, controlling for other variables that may interfere in such a relation. Study comprising 83 overweight and obese adolescents (BMI > or = P85) and 89 non obese ones (P5 < or = BMI < or = P85). Cases and controls were selected out of 1,420 students (aged 14-19) from a public school in the city of São Paulo. The bone mineral density of the lumbar spine (L2-L4 in g/cm2) was assessed by dual-energy x-ray absorptiometry (LUNARtrade mark DPX-L). The variable bone density was dichotomized using 1.194 g/cm2 as cutoff point. Bivariate analyses were conducted considering the prevalence of overweight and obesity followed by multivariate analysis (logistic regression) according to a hierarchical conceptual model. The prevalence of bone density above the median was twice more frequent among cases (69.3%) than among controls (32.1%). In the bivariate analysis such prevalence resulted in an odds ratio (OR) of 4.78. The logistic regression model showed that the association between obesity and mineral density is yet more intense with an OR of 6.65 after the control of variables related to sedentary lifestyle and intake of milk and dairy products. Obese and overweight adolescents in the final stages of sexual maturity presented higher bone mineral density in relation to their normal-weight counterparts; however, cohort studies will be necessary to evaluate the influence of such characteristic on bone resistance in adulthood and, consequently, on the incidence of osteopenia and osteoporosis at older ages.

Form-function analysis of the effect of canopy morphology on leaf self-shading in the seagrass Thalassia testudinum.

PubMed

Enríquez, Susana; Pantoja-Reyes, Norma I

2005-09-01

The variation in seagrass morphology and the magnitude of leaf self-shading within the canopy of Thalassia testudinum, were compared among nine sites in a fringing reef lagoon. We found a significant variation in the growth-form of T. testudinum reflected in a 5.4-fold variation in the attenuation coefficient (K (d)) within the canopy. The largest morphological variation was observed in shoot density. Leaf biomass, leaf area index (LAI), and shoot density were positively associated with canopy-K (d) and with the percentage of surface irradiance received by the top of the seagrass canopy (% Es). These results provide an explanation for the consistent pattern of depth reduction in seagrass leaf biomass and shoot density reported in the literature. Shoot density and shoot size are two descriptors of the growth-form of T. testudinum related to its clonal life-form. Shoot size was not significantly correlated with canopy-K (d), nevertheless, it showed a significant effect on the slope of the relationship between shoot density and canopy-K (d). According to this model, shoot size also contributes to light attenuation within the seagrass canopy by increasing the effect of shoot density. This form-function analysis suggests that light may have a relevant role in the regulation of the optimal plant balance between horizontal (variation in shoot density) and vertical (variation in shoot size) growth of seagrasses. Other environmental factors and interactions also need to be examined to fully understand the mechanistic bases of the morphological responses of seagrasses to the environment.

The validation of tomotherapy dose calculations in low-density lung media

NASA Astrophysics Data System (ADS)

Chaudhari, Summer R.; Pechenaya, Olga L.; Goddu, S. Murty; Mutic, Sasa; Rangaraj, Dharanipathy; Bradley, Jeffrey D.; Low, Daniel

2009-04-01

The dose-calculation accuracy of the tomotherapy Hi-Art II® (Tomotherapy, Inc., Madison, WI) treatment planning system (TPS) in the presence of low-density lung media was investigated. In this evaluation, a custom-designed heterogeneous phantom mimicking the mediastinum geometry was used. Gammex LN300 and balsa wood were selected as two lung-equivalent materials with different densities. Film analysis and ionization chamber measurements were performed. Treatment plans for esophageal cancers were used in the evaluation. The agreement between the dose calculated by the TPS and the dose measured via ionization chambers was, in most cases, within 0.8%. Gamma analysis using 3% and 3 mm criteria for radiochromic film dosimetry showed that 98% and 95% of the measured dose distribution had passing gamma values <=1 for LN300 and balsa wood, respectively. For a homogeneous water-equivalent phantom, 95% of the points passed the gamma test. It was found that for the interface between the low-density medium and water-equivalent medium, the TPS calculated the dose distribution within acceptable limits. The phantom developed for this work enabled detailed quality-assurance testing under realistic conditions with heterogeneous media.

An analysis of urban thermal characteristics and associated land cover in Tampa Bay and Las Vegas using Landsat satellite data

USGS Publications Warehouse

Xian, George; Crane, Mike

2006-01-01

Remote sensing data from both Landsat 5 and Landsat 7 systems were utilized to assess urban area thermal characteristics in Tampa Bay watershed of west-central Florida, and the Las Vegas valley of southern Nevada. To quantitatively determine urban land use extents and development densities, sub-pixel impervious surface areas were mapped for both areas. The urban–rural boundaries and urban development densities were defined by selecting certain imperviousness threshold values and Landsat thermal bands were used to investigate urban surface thermal patterns. Analysis results suggest that urban surface thermal characteristics and patterns can be identified through qualitatively based urban land use and development density data. Results show the urban area of the Tampa Bay watershed has a daytime heating effect (heat-source), whereas the urban surface in Las Vegas has a daytime cooling effect (heat-sink). These thermal effects strongly correlated with urban development densities where higher percent imperviousness is usually associated with higher surface temperature. Using vegetation canopy coverage information, the spatial and temporal distributions of urban impervious surface and associated thermal characteristics are demonstrated to be very useful sources in quantifying urban land use, development intensity, and urban thermal patterns.

Measurement of Average Aggregate Density by Sedimentation and Brownian Motion Analysis.

PubMed

Cavicchi, Richard E; King, Jason; Ripple, Dean C

2018-05-01

The spatially averaged density of protein aggregates is an important parameter that can be used to relate size distributions measured by orthogonal methods, to characterize protein particles, and perhaps to estimate the amount of protein in aggregate form in a sample. We obtained a series of images of protein aggregates exhibiting Brownian diffusion while settling under the influence of gravity in a sealed capillary. The aggregates were formed by stir-stressing a monoclonal antibody (NISTmAb). Image processing yielded particle tracks, which were then examined to determine settling velocity and hydrodynamic diameter down to 1 μm based on mean square displacement analysis. Measurements on polystyrene calibration microspheres ranging in size from 1 to 5 μm showed that the mean square displacement diameter had improved accuracy over the diameter derived from imaged particle area, suggesting a future method for correcting size distributions based on imaging. Stokes' law was used to estimate the density of each particle. It was found that the aggregates were highly porous with density decreasing from 1.080 to 1.028 g/cm 3 as the size increased from 1.37 to 4.9 μm. Published by Elsevier Inc.

Comprehensive analysis of soil nitrogen removal by catch crops based on growth and water use

NASA Astrophysics Data System (ADS)

Yasutake, D.; Kondo, K.; Yamane, S.; Kitano, M.; Mori, M.; Fujiwara, T.

2016-07-01

A new methodology for comprehensive analysis of the characteristics of nitrogen (N) removal from greenhouse soil by catch crop was proposed in relation to its growth and water use. The N removal is expressed as the product of five parameters: net assimilation rate, specific leaf area, shoot dry weight, water use efficiency for N removal, and water requirement for growth. This methodology was applied to the data of a greenhouse experiment where corn was cultivated under three plant densities. We analyzed the effect of plant density and examined the effectiveness of the methodology. Higher plant densities are advantageous not only for total N removal but also for water use efficiency in N removal and growth because of the large specific leaf area, shoot dry weight, and decreased soil evaporation. On the other hand, significant positive or negative linear relationships were found between all five parameters and N removal. This should improve the understanding of the N removal mechanisms and the interactions among its components. We show the effectiveness of our analytical methodology, which can contribute to identifying the optimum plant density according to the field situations (available water amount, soil N quantity to be removed) for practical catch crop cultivation.

The validation of tomotherapy dose calculations in low-density lung media.

PubMed

Chaudhari, Summer R; Pechenaya, Olga L; Goddu, S Murty; Mutic, Sasa; Rangaraj, Dharanipathy; Bradley, Jeffrey D; Low, Daniel

2009-04-21

The dose-calculation accuracy of the tomotherapy Hi-Art II(R) (Tomotherapy, Inc., Madison, WI) treatment planning system (TPS) in the presence of low-density lung media was investigated. In this evaluation, a custom-designed heterogeneous phantom mimicking the mediastinum geometry was used. Gammex LN300 and balsa wood were selected as two lung-equivalent materials with different densities. Film analysis and ionization chamber measurements were performed. Treatment plans for esophageal cancers were used in the evaluation. The agreement between the dose calculated by the TPS and the dose measured via ionization chambers was, in most cases, within 0.8%. Gamma analysis using 3% and 3 mm criteria for radiochromic film dosimetry showed that 98% and 95% of the measured dose distribution had passing gamma values < or =1 for LN300 and balsa wood, respectively. For a homogeneous water-equivalent phantom, 95% of the points passed the gamma test. It was found that for the interface between the low-density medium and water-equivalent medium, the TPS calculated the dose distribution within acceptable limits. The phantom developed for this work enabled detailed quality-assurance testing under realistic conditions with heterogeneous media.

Electron-boson spectral density function of correlated multiband systems obtained from optical data: Ba0.6K0.4Fe2As2 and LiFeAs.

PubMed

Hwang, Jungseek

2016-03-31

We introduce an approximate method which can be used to simulate the optical conductivity data of correlated multiband systems for normal and superconducting cases by taking advantage of a reversed process in comparison to a usual optical data analysis, which has been used to extract the electron-boson spectral density function from measured optical spectra of single-band systems, like cuprates. We applied this method to optical conductivity data of two multiband pnictide systems (Ba0.6K0.4Fe2As2 and LiFeAs) and obtained the electron-boson spectral density functions. The obtained electron-boson spectral density consists of a sharp mode and a broad background. The obtained spectral density functions of the multiband systems show similar properties as those of cuprates in several aspects. We expect that our method helps to reveal the nature of strong correlations in the multiband pnictide superconductors.

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.

A fragment substitution in the promoter of CsHDZIV11/CsGL3 is responsible for fruit spine density in cucumber (Cucumis sativus L.).

PubMed

Zhang, Haiyang; Wang, Lina; Zheng, Shuangshuang; Liu, Zezhou; Wu, Xiaoqin; Gao, Zhihui; Cao, Chenxing; Li, Qiang; Ren, Zhonghai

2016-07-01

The indel in the promoter of CsHDZIV11 co-segregates with fruit spine density and could be used for molecular breeding in cucumber. Fruit spine density is an important quality trait for marketing in cucumber (Cucumis sativus L.). However, the molecular basis of fruit spine density in cucumber remains unclear. In this study, we isolated a mutant, few spines 1 (fs1), from CNS2 (wild type, WT), a North China-type cucumber with a high density of fruit spines. Genetic analysis showed that fs1 was controlled by a single recessive Mendelian factor. Bulked segregant analysis combined with genome resequencing were used for mapping fs1 in the F2 population derived from a cross between the fs1 mutant and WT, and it was located on chromosome 6 through association analysis. To develop more polymorphic markers to locate fs1, another F2 population was constructed from the cross between fs1 and 'Chinese long' 9930. Then, fs1 was narrowed down to a 110.4-kb genomic region containing 25 annotated genes. A fragment substitution was identified in the promoter region of Csa6M514870 between fs1 and WT. This fragment in fs1 was also present in wild cucumber. Csa6M514870 encodes a PDF2-related protein, a homeodomain-leucine zipper IV transcription factor (CsHDZIV11/CsGL3) sharing high identity and similarity with proteins related to trichome formation or epidermal cell differentiation. Quantitative reverse-transcription PCR revealed a higher expression level of CsHDZIV11 in young fruits from fs1 compared to WT. A molecular marker based on this indel co-segregated with the spine density. This work provides a solid foundation not only for understanding the molecular mechanism of fruit spine density, but also for molecular breeding in cucumber.

Daytime warming has stronger negative effects on soil nematodes than night-time warming.

PubMed

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-07

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Daytime warming has stronger negative effects on soil nematodes than night-time warming.

PubMed

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-20

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Comparison of the far-infrared and carbon monoxide emission in Heiles' Cloud 2 and B18

NASA Technical Reports Server (NTRS)

Snell, Ronald L.; Schloerb, F. Peter; Heyer, Mark H.

1989-01-01

A comparison is made of the far-IR emission detected by IRAS at 60 and 100 microns and the emission from C(-13)O in B18 and Heiles' Cloud 2. The results show that both these clouds have extended emission at the studied wavelengths and that this emission is correlated with the integrated intensity of (C-13)O emission. The dust temperature and optical depth, the gas column density, the mass of gas and dust, and the far-IR luminosity are derived and presented. The analysis shows that the dust optical depth is much better correlated with the gas column density than with the far-IR intensity. The dust temperature is found to be anticorrelated with the gas column density, suggesting that these clouds are externally heated by the interstellar radiation field. The far-IR luminosity-to-mass ratios for the clouds are substantially less than the average for the inner Galaxy.

Linear unsaturating magnetoresistance in disordered systems

NASA Astrophysics Data System (ADS)

Lai, Ying Tong; Lara, Silvia; Love, Cameron; Ramakrishnan, Navneeth; Adam, Shaffique

Theoretical works have shown that disordered systems exhibit classical magnetoresistance (MR). In this talk, we examine a variety of experimental systems that observe linear MR at high magnetic fields, including silver chalcogenides, graphene, graphite and Weyl semimetals. We show that a careful analysis of the magnitude of the MR, as well as the field strength at which the MR changes from quadratic to linear, reveal important properties of the system, such as the ratio of the root-mean-square fluctuations in the carrier density and the average carrier density. By looking at other properties such as the zero-field mobility, we show that this carrier density inhomogeneity is consistent with what is known about the microscopic impurities in these experiments. The application of this disorder-induced MR to a variety of different experimental scenarios underline the universality of these theoretical models. This work is supported by the Singapore National Research Foundation (NRF-NRFF2012-01) and the Singapore Ministry of Education and Yale-NUS College through Grant Number R-607-265-01312.

Daytime warming has stronger negative effects on soil nematodes than night-time warming

PubMed Central

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-01-01

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming. PMID:28317914

Daytime warming has stronger negative effects on soil nematodes than night-time warming

NASA Astrophysics Data System (ADS)

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-01

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Occurrence of the dayside three-peak density structure in the F2 and the topside ionosphere

NASA Astrophysics Data System (ADS)

Astafyeva, Elvira; Zakharenkova, Irina; Pineau, Yann

2016-07-01

In this work, we discuss the occurrence of the dayside three-peak electron density structure in the ionosphere. We first use a set of ground-based and satellite-borne instruments to demonstrate the development of a large-amplitude electron density perturbation at the recovery phase of a moderate storm of 11 October 2008. The perturbation developed in the F2 and low topside ionospheric regions over the American sector; it was concentrated on the north from the equatorial ionization anomaly (EIA) but was clearly separated from it. At the F2 region height, the amplitude of the observed perturbation was comparable or even exceeded that of the EIA. Further analysis of the observational data together with the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics model simulation results showed that a particular local combination of the thermospheric wind surges provided favorable conditions for the generation of the three-peak EIA structure. We further proceed with a statistical study of occurrence of the three-peak density structure in the ionosphere in general. Based on the analysis of 7 years of the in situ data from CHAMP satellite, we found that such three-peak density structure occurs sufficiently often during geomagnetically quiet time. The third ionization peak develops in the afternoon hours in the summer hemisphere at solstice periods. Based on analysis of several quiet time events, we conclude that during geomagnetically quiet time, the prevailing summer-to-winter thermospheric circulation acts in similar manner as the storm-time enhanced thermospheric winds, playing the decisive role in generation of the third ionization peak in the daytime ionosphere.

Bone density and depressive disorder: a meta-analysis.

PubMed

Schweiger, Julietta Ursula; Schweiger, Ulrich; Hüppe, Michael; Kahl, Kai G; Greggersen, Wiebke; Fassbinder, Eva

2016-08-01

The aim of this study was to evaluate the evidence of low bone mineral density (BMD) in depression. Low BMD is a major risk factor for osteoporotic fractures and frailty. The searched database was Pubmed, Meta-analysis included human studies in men and women fulfilling the following criteria: (1) assessment of BMD in the lumbar spine, the femur or the total hip; (2) comparison of BMD between depressed individuals and the healthy control group; (3) measurement of BMD using dual-energy X-ray absorptiometry (DEXA); and (4) data on the mean, standard deviation, or standard error of BMD. Twenty-one studies were identified, encompassing 1842 depressed and 17,401 nondepressed individuals. Significant negative composite weighted mean effect sizes were identified for the lumbar spine (d = -0.15, 95%CL -0.22 to -0.08), femur (d = -0.34, 95%CL -0.64 to -0.05), and total hip (d = -0.14, 95%CL -0.23 to -0.05) indicating low BMD in depression. Examining men and women shows low bone density in the lumbar spine and femur in women and low bone density in the hip in men. The differences between men and women with MDD and the comparison group tended to be higher when examined by expert interviewers. Low bone density was found in all age groups. Bone mineral density is reduced in patients with depressive disorders. The studies provide little evidence for potential relevant mediating factors.

ERP Energy and Cognitive Activity Correlates

NASA Astrophysics Data System (ADS)

Schillaci, Michael Jay; Vendemia, Jennifer M. C.

2014-03-01

We propose a novel analysis approach for high-density event related scalp potential (ERP) data where the integrated channel-power is used to attain an energy density functional state for channel-clusters of neurophysiological significance. The method is applied to data recorded during a two-stimulus, directed lie paradigm and shows that deceptive responses emit between 8% and 10% less power. A time course analysis of these cognitive activity measures over posterior and anterior regions of the cortex suggests that neocortical interactions, reflecting the differing workload demands during executive and semantic processes, take about 50% longer for the case of deception. These results suggest that the proposed method may provide a useful tool for the analysis of ERP correlates of high-order cognitive functioning. We also report on a possible equivalence between the energy functional distribution and near-infrared signatures that have been measured with other modalities.

Synthesis, characterization, AIM and NBO analysis of HMX/DMI cocrystal explosive

NASA Astrophysics Data System (ADS)

Lin, He; Zhu, Shun-Guan; Li, Hong-Zhen; Peng, Xin-Hua

2013-09-01

1,3,5,7-Tetranitro-1,3,5,7-tetrazacyclooctane (HMX)/1,3-dimethyl-2-imidazolidinone (DMI) cocrystal explosive was synthesized and characterized by using X-ray single crystal diffraction. HMX/DMI cocrystal crystallizes in the monoclinic system (space group Cm), with cell parameters a = 7.231(2)Å, b = 14.739(2)Å, c = 7.552(1)Å, β = 96.66°. In addition, density functional theory, involving binding energy, natural bond orbital (NBO) analysis, atoms in molecule (AIM) analysis, band structure, and density of states, was adopted to investigate intermolecular interactions for the formation of HMX/DMI cocrystal. The results show that hydrogen bondings between methylene groups of HMX molecules and O atoms of DMI molecules are the main intermolecular interactions. This research provides the basis for further design of cocrystal explosives, which are composed of HMX and energetic materials.

Natural bond orbital analysis, electronic structure, non-linear properties and vibrational spectral analysis of L-histidinium bromide monohydrate: a density functional theory.

PubMed

Sajan, D; Joseph, Lynnette; Vijayan, N; Karabacak, M

2011-10-15

The spectroscopic properties of the crystallized nonlinear optical molecule L-histidinium bromide monohydrate (abbreviated as L-HBr-mh) have been recorded and analyzed by FT-IR, FT-Raman and UV techniques. The equilibrium geometry, vibrational wavenumbers and the first order hyperpolarizability of the crystal were calculated with the help of density functional theory computations. The optimized geometric bond lengths and bond angles obtained by using DFT (B3LYP/6-311++G(d,p)) show good agreement with the experimental data. The complete assignments of fundamental vibrations were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The natural bond orbital (NBO) analysis confirms the occurrence of strong intra and intermolecular N-H⋯O hydrogen bonding. Copyright © 2011 Elsevier B.V. All rights reserved.

SEMICONDUCTOR TECHNOLOGY: Influence of nitrogen dose on the charge density of nitrogen-implanted buried oxide in SOI wafers

NASA Astrophysics Data System (ADS)

Zhongshan, Zheng; Zhongli, Liu; Ning, Li; Guohua, Li; Enxia, Zhang

2010-02-01

To harden silicon-on-insulator (SOI) wafers fabricated using separation by implanted oxygen (SIMOX) to total-dose irradiation, the technique of nitrogen implantation into the buried oxide (BOX) layer of SIMOX wafers can be used. However, in this work, it has been found that all the nitrogen-implanted BOX layers reveal greater initial positive charge densities, which increased with increasing nitrogen implantation dose. Also, the results indicate that excessively large nitrogen implantation dose reduced the radiation tolerance of BOX for its high initial positive charge density. The bigger initial positive charge densities can be ascribed to the accumulation of implanted nitrogen near the Si-BOX interface after annealing. On the other hand, in our work, it has also been observed that, unlike nitrogen-implanted BOX, all the fluorine-implanted BOX layers show a negative charge density. To obtain the initial charge densities of the BOX layers, the tested samples were fabricated with a metal-BOX-silicon (MBS) structure based on SIMOX wafers for high-frequency capacitance-voltage (C-V) analysis.

Investigation of a complete sample of flat spectrum radio sources from the S5 survey

NASA Astrophysics Data System (ADS)

Eckart, A.; Witzel, A.; Biermann, P.; Johnston, K. J.; Simon, R.; Schalinski, C.; Kuhr, H.

1986-11-01

An analysis of 13 extragalactic sources of the S5 survey with flux densities greater than or equal to 1 Jy at 4990 MHz, mapped with milliarcsecond resolution at 1.6 and 5 GHz by means of VLBI, is presented. All sources appear to display multiple components dominated in flux density at 6 cm by a core component which is self-absorbed at 18 cm. Comparison of the measured to predicted X-ray flux density of the core radio components suggests that all sources should display bulk relativistic motion with small angles to the line of sight, and four sources show rapid changes in their radio structures which can be interpreted as apparent superliminal motion.

The Effect of the Density Ratio on the Nonlinear Dynamics of the Unstable Fluid Interface

NASA Technical Reports Server (NTRS)

Abarzhi, S. I.

2003-01-01

Here we report multiple harmonic theoretical solutions for a complete system of conservation laws, which describe the large-scale coherent dynamics in RTI and RMI for fluids with a finite density ratio in the general three-dimensional case. The analysis yields new properties of the bubble front dynamics. In either RTI or RMI, the obtained dependencies of the bubble velocity and curvature on the density ratio differ qualitatively and quantitatively from those suggested by the models of Sharp (1984), Oron et al. (2001), and Goncharov (2002). We show explicitly that these models violate the conservation laws. For the first time, our theory reveals an important qualitative distinction between the dynamics of the RT and RM bubbles.

Attractor Dynamics and Semantic Neighborhood Density: Processing Is Slowed by Near Neighbors and Speeded by Distant Neighbors

PubMed Central

Mirman, Daniel; Magnuson, James S.

2008-01-01

The authors investigated semantic neighborhood density effects on visual word processing to examine the dynamics of activation and competition among semantic representations. Experiment 1 validated feature-based semantic representations as a basis for computing semantic neighborhood density and suggested that near and distant neighbors have opposite effects on word processing. Experiment 2 confirmed these results: Word processing was slower for dense near neighborhoods and faster for dense distant neighborhoods. Analysis of a computational model showed that attractor dynamics can produce this pattern of neighborhood effects. The authors argue for reconsideration of traditional models of neighborhood effects in terms of attractor dynamics, which allow both inhibitory and facilitative effects to emerge. PMID:18194055

Serum cholesterol and risk of lower urinary tract symptoms progression: Results from the Reduction by Dutasteride of Prostate Cancer Events study.

PubMed

Feng, Tom; Howard, Lauren E; Vidal, Adriana C; Moreira, Daniel M; Castro-Santamaria, Ramiro; Andriole, Gerald L; Freedland, Stephen J

2017-02-01

To determine if cholesterol is a risk factor for the development of lower urinary tract symptoms in asymptomatic men. A post-hoc analysis of the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) study was carried out in 2323 men with baseline International Prostate Symptom Score <8 and not taking benign prostatic hyperplasia or cholesterol medications. Cox proportion models were used to test the association between cholesterol, high-density lipoprotein, low-density lipoprotein and the cholesterol : high-density lipoprotein ratio with incident lower urinary tract symptoms, defined as first report of medical treatment, surgery or two reports of an International Prostate Symptom Score >14. A total of 253 men (10.9%) developed incident lower urinary tract symptoms. On crude analysis, higher high-density lipoprotein was associated with a decreased lower urinary tract symptoms risk (hazard ratio 0.89, P = 0.024), whereas total cholesterol and low-density lipoprotein showed no association. After multivariable adjustment, the association between high-density lipoprotein and incident lower urinary tract symptoms remained significant (hazard ratio 0.89, P = 0.044), whereas no association was observed for low-density lipoprotein (P = 0.611). There was a trend for higher cholesterol to be linked with higher lower urinary tract symptoms risk, though this was not statistically significant (hazard ratio 1.04, P = 0.054). A higher cholesterol : high-density lipoprotein ratio was associated with increased lower urinary tract symptoms risk on crude (hazard ratio 1.11, P = 0.016) and adjusted models (hazard ratio 1.12, P = 0.012). Among asymptomatic men participating in the REDUCE study, higher cholesterol was associated with increased incident lower urinary tract symptoms risk, though the association was not significant. A higher cholesterol : high-density lipoprotein ratio was associated with increased incident lower urinary tract symptoms, whereas higher high-density lipoprotein was protective. These findings suggest dyslipidemia might play a role in lower urinary tract symptoms progression. © 2016 The Japanese Urological Association.

High microvessel density determines a poor outcome in patients with diffuse large B-cell lymphoma treated with rituximab plus chemotherapy

PubMed Central

Cardesa-Salzmann, Teresa M.; Colomo, Luis; Gutierrez, Gonzalo; Chan, Wing C.; Weisenburger, Dennis; Climent, Fina; González-Barca, Eva; Mercadal, Santiago; Arenillas, Leonor; Serrano, Sergio; Tubbs, Ray; Delabie, Jan; Gascoyne, Randy D.; Connors, Joseph M; Mate, Jose L.; Rimsza, Lisa; Braziel, Rita; Rosenwald, Andreas; Lenz, Georg; Wright, George; Jaffe, Elaine S.; Staudt, Louis; Jares, Pedro; López-Guillermo, Armando; Campo, Elias

2011-01-01

Background Diffuse large B-cell lymphoma is a clinically and molecularly heterogeneous disease. Gene expression profiling studies have shown that the tumor microenvironment affects survival and that the angiogenesis-related signature is prognostically unfavorable. The contribution of histopathological microvessel density to survival in diffuse large B-cell lymphomas treated with immunochemotherapy remains unknown. The purpose of this study is to assess the prognostic impact of histopathological microvessel density in two independent series of patients with diffuse large B-cell lymphoma treated with immunochemotherapy. Design and Methods One hundred and forty-seven patients from the Leukemia Lymphoma Molecular Profiling Project (training series) and 118 patients from the Catalan Lymphoma-Study group-GELCAB (validation cohort) were included in the study. Microvessels were immunostained with CD31 and quantified with a computerized image analysis system. The stromal scores previously defined in 110 Leukemia Lymphoma Molecular Profiling Project cases were used to analyze correlations with microvessel density data. Results Microvessel density significantly correlated with the stromal score (r=0.3209; P<0.001). Patients with high microvessel density showed significantly poorer overall survival than those with low microvessel density both in the training series (4-year OS 54% vs. 78%; P=0.004) and in the validation cohort (57% vs. 81%; P=0.006). In multivariate analysis, in both groups high microvessel density was a statistically significant unfavorable prognostic factor independent of international prognostic index [training series: international prognostic index (relative risk 2.7; P=0.003); microvessel density (relative risk 1.96; P=0.002); validation cohort: international prognostic index (relative risk 4.74; P<0.001); microvessel density (relative risk 2.4; P=0.016)]. Conclusions These findings highlight the impact of angiogenesis in the outcome of patients with diffuse large B-cell lymphoma and the interest of evaluating antiangiogenic drugs in clinical trials. PMID:21546504

Variability of footprint ridge density and its use in estimation of sex in forensic examinations.

PubMed

Krishan, Kewal; Kanchan, Tanuj; Pathania, Annu; Sharma, Ruchika; DiMaggio, John A

2015-10-01

The present study deals with a comparatively new biometric parameter of footprints called footprint ridge density. The study attempts to evaluate sex-dependent variations in ridge density in different areas of the footprint and its usefulness in discriminating sex in the young adult population of north India. The sample for the study consisted of 160 young adults (121 females) from north India. The left and right footprints were taken from each subject according to the standard procedures. The footprints were analysed using a 5 mm × 5 mm square and the ridge density was calculated in four different well-defined areas of the footprints. These were: F1 - the great toe on its proximal and medial side; F2 - the medial ball of the footprint, below the triradius (the triradius is a Y-shaped group of ridges on finger balls, palms and soles which forms the basis of ridge counting in identification); F3 - the lateral ball of the footprint, towards the most lateral part; and F4 - the heel in its central part where the maximum breadth at heel is cut by a perpendicular line drawn from the most posterior point on heel. This value represents the number of ridges in a 25 mm(2) area and reflects the ridge density value. Ridge densities analysed on different areas of footprints were compared with each other using the Friedman test for related samples. The total footprint ridge density was calculated as the sum of the ridge density in the four areas of footprints included in the study (F1 + F2 + F3 + F4). The results show that the mean footprint ridge density was higher in females than males in all the designated areas of the footprints. The sex differences in footprint ridge density were observed to be statistically significant in the analysed areas of the footprint, except for the heel region of the left footprint. The total footprint ridge density was also observed to be significantly higher among females than males. A statistically significant correlation is shown in the ridge densities among most areas of both left and right sides. Based on receiver operating characteristic (ROC) curve analysis, the sexing potential of footprint ridge density was observed to be considerably higher on the right side. The sexing potential for the four areas ranged between 69.2% and 85.3% on the right side, and between 59.2% and 69.6% on the left side. ROC analysis of the total footprint ridge density shows that the sexing potential of the right and left footprint was 91.5% and 77.7% respectively. The study concludes that footprint ridge density can be utilised in the determination of sex as a supportive parameter. The findings of the study should be utilised only on the north Indian population and may not be internationally generalisable. © The Author(s) 2014.

Segmentation of the Knee for Analysis of Osteoarthritis

NASA Astrophysics Data System (ADS)

Zerfass, Peter; Museyko, Oleg; Bousson, Valérie; Laredo, Jean-Denis; Kalender, Willi A.; Engelke, Klaus

Osteoarthritis changes the load distribution within joints and also changes bone density and structure. Within typical timelines of clinical studies these changes can be very small. Therefore precise definition of evaluation regions which are highly robust and show little to no interand intra-operator variance are essential for high quality quantitative analysis. To achieve this goal we have developed a system for the definition of such regions with minimal user input.

Analysis of the Central X-ray Source in DG Tau

NASA Astrophysics Data System (ADS)

Schneider, P. Christian; Schmitt, Jürgen H. M. M.

As a stellar X-ray source DG Tau shows two rather unusual features: A resolved X-ray jet [2] and an X-ray spectrum best described by two thermal components with different absorbing column densities, a so called "two-absorber X-ray (TAX)" morphology [1, 2]. In an effort to understand the properties of the central X-ray source in DG Tau a detailed position analysis was carried out.

Annual asymmetry in thermospheric density: Observations and simulations

NASA Astrophysics Data System (ADS)

Lei, Jiuhou; Dou, Xiankang; Burns, Alan; Wang, Wenbin; Luan, Xiaoli; Zeng, Zhen; Xu, Jiyao

2013-05-01

In this paper, the Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) observations during 2002-2010 are utilized to study the variation of the annual asymmetry in thermospheric density at 400 km under low solar activity condition (F10.7 = 80) based on the method of empirical orthogonal functions (EOFs). The derived asymmetry index (AI) in thermospheric density from the EOF analysis shows a strong latitudinal variation at night but varies a little with latitudes in daytime. Moreover, it exhibits a terdiurnal tidal signature at low to middle latitudes. The global mean value of the AI is 0.191, indicating that a 47% difference in thermosphere between the December and June solstices in the global average. In addition, the NCAR Thermosphere-Ionosphere Electrodynamics Global Circulation Model (TIEGCM) is used to explore the possible mechanisms responsible for the observed annual asymmetry in thermospheric density. It is found that the standard simulations give a lower AI and also a weaker day-to-night difference. The simulated AI shows a semidiurnal pattern in the equatorial and low-latitude regions in contrast with the terdiurnal tide signature seen in the observed AI. The daily mean AI obtained from the simulation is 0.125, corresponding to a 29% December-to-June difference in thermospheric density at 400 km. Further sensitivity simulations demonstrated that the effect of the varying Sun-Earth distance between the December and June solstices is the main process responsible for the annual asymmetry in thermospheric density, while the magnetic field configuration and tides from the lower atmosphere contribute to the temporal and spatial variations of the AI. Specifically, the simulations show that the Sun-Earth distance effect explains 93% of the difference in thermospheric density between December and June, which is mainly associated with the corresponding changes in neutral temperature. However, our calculation from the density observations reveals that the varying Sun-Earth distance effect only accounts for ~67% of the December-to-June difference in thermosphere density, indicating that the TIEGCM might significantly underestimate the forcing originating from the lower atmosphere.

Surrogate immiscible liquid pairs with refractive indexes matchable over a wide range of density and viscosity ratios

NASA Astrophysics Data System (ADS)

Saksena, Rajat; Christensen, Kenneth T.; Pearlstein, Arne J.

2015-08-01

In liquid-liquid flows, use of optical diagnostics is limited by interphase refractive index mismatch, which leads to optical distortion and complicates data interpretation, and sometimes also by opacity. Both problems can be eliminated using a surrogate pair of immiscible index-matched transparent liquids, whose density and viscosity ratios match corresponding ratios for the original liquid pair. We show that a wide range of density and viscosity ratios is accessible using aqueous solutions of 1,2-propanediol and CsBr (for which index, density, and viscosity are available), and solutions of light and heavy silicone oils and 1-bromooctane (for which we measured the same properties at 119 compositions). For each liquid phase, polynomials in the composition variables, least-squares fitted to index and density and to the logarithm of kinematic viscosity, were used to determine accessible density and viscosity ratios for each matchable index. Index-matched solution pairs can be prepared with density and viscosity ratios equal to those for water-liquid CO2 at 0 °C over a range of pressure (allowing water-liquid CO2 behavior at inconveniently high pressure to be simulated by 1-bar experiments), and for water-crude oil and water-trichloroethylene (avoiding opacity and toxicity problems, respectively), each over a range of temperature. For representative index-matched solutions, equilibration changes index, density, and viscosity only slightly, and mass spectrometry and elemental analysis show that no component of either phase has significant interphase solubility. Finally, procedures are described for iteratively reducing the residual index mismatch in surrogate solution pairs prepared on the basis of approximate polynomial fits to experimental data, and for systematically dealing with nonzero interphase solubility.

Laboratory-Scale Internal Wave Apparatus for Studying Copepod Behavior

NASA Astrophysics Data System (ADS)

Jung, S.; Webster, D. R.; Haas, K. A.; Yen, J.

2016-02-01

Internal waves are ubiquitous features in coastal marine environments and have been observed to mediate vertical distributions of zooplankton in situ. Internal waves create fine-scale hydrodynamic cues that copepods and other zooplankton are known to sense, such as fluid density gradients and velocity gradients (quantified as shear deformation rate). The role of copepod behavior in response to cues associated with internal waves is largely unknown. The objective is to provide insight to the bio-physical interaction and the role of biological versus physical forcing in mediating organism distributions. We constructed a laboratory-scale internal wave apparatus to facilitate fine-scale observations of copepod behavior in flows that replicate in situ conditions of internal waves in two-layer stratification. Two cases were chosen with density jump of 1 and 1.5 sigma-t units. Analytical analysis of the two-layer system provided guidance to the target forcing frequency needed to generate a standing internal wave with a single dominate frequency of oscillation. Flow visualization and signal processing of the interface location were used to quantify the wave characteristics. The results show a close match to the target wave parameters. Marine copepod (mixed population of Acartia tonsa, Temora longicornis, and Eurytemora affinis) behavior assays were conducted for three different physical arrangements: (1) no density stratification, (2) stagnant two-layer density stratification, and (3) two-layer density stratification with internal wave motion. Digitized trajectories of copepod swimming behavior indicate that in the control (case 1) the animals showed no preferential motion in terms of direction. In the stagnant density jump treatment (case 2) copepods preferentially moved horizontally, parallel to the density interface. In the internal wave treatment (case 3) copepods demonstrated orbital trajectories near the density interface.

A density distribution algorithm for bone incorporating local orthotropy, modal analysis and theories of cellular solids.

PubMed

Impelluso, Thomas J

2003-06-01

An algorithm for bone remodeling is presented which allows for both a redistribution of density and a continuous change of principal material directions for the orthotropic material properties of bone. It employs a modal analysis to add density for growth and a local effective strain based analysis to redistribute density. General re-distribution functions are presented. The model utilizes theories of cellular solids to relate density and strength. The code predicts the same general density distributions and local orthotropy as observed in reality.

Insect density-plant density relationships: a modified view of insect responses to resource concentrations.

PubMed

Andersson, Petter; Löfstedt, Christer; Hambäck, Peter A

2013-12-01

Habitat area is an important predictor of spatial variation in animal densities. However, the area often correlates with the quantity of resources within habitats, complicating our understanding of the factors shaping animal distributions. We addressed this problem by investigating densities of insect herbivores in habitat patches with a constant area but varying numbers of plants. Using a mathematical model, predictions of scale-dependent immigration and emigration rates for insects into patches with different densities of host plants were derived. Moreover, a field experiment was conducted where the scaling properties of odour-mediated attraction in relation to the number of odour sources were estimated, in order to derive a prediction of immigration rates of olfactory searchers. The theoretical model predicted that we should expect immigration rates of contact and visual searchers to be determined by patch area, with a steep scaling coefficient, μ = -1. The field experiment suggested that olfactory searchers should show a less steep scaling coefficient, with μ ≈ -0.5. A parameter estimation and analysis of published data revealed a correspondence between observations and predictions, and density-variation among groups could largely be explained by search behaviour. Aphids showed scaling coefficients corresponding to the prediction for contact/visual searchers, whereas moths, flies and beetles corresponded to the prediction for olfactory searchers. As density responses varied considerably among groups, and variation could be explained by a certain trait, we conclude that a general theory of insect responses to habitat heterogeneity should be based on shared traits, rather than a general prediction for all species.

Heterochromatic Flicker Photometry for Objective Lens Density Quantification.

PubMed

Najjar, Raymond P; Teikari, Petteri; Cornut, Pierre-Loïc; Knoblauch, Kenneth; Cooper, Howard M; Gronfier, Claude

2016-03-01

Although several methods have been proposed to evaluate lens transmittance, to date there is no consensual in vivo approach in clinical practice. The aim of this study was to compare ocular lens density and transmittance measurements obtained by an improved psychophysical scotopic heterochromatic flicker photometry (sHFP) technique to the results obtained by three other measures: a psychophysical threshold technique, a Scheimpflug imaging technique, and a clinical assessment using a validated subjective scale. Forty-three subjects (18 young, 9 middle aged, and 16 older) were included in the study. Individual lens densities were measured and transmittance curves were derived from sHFP indexes. Ocular lens densities were compared across methods by using linear regression analysis. The four approaches showed a quadratic increase in lens opacification with age. The sHFP technique revealed that transmittance decreased with age over the entire visual spectrum. This decrease was particularly pronounced between young and older participants in the short (53.03% decrease in the 400-500 nm range) wavelength regions of the light spectrum. Lens density derived from sHFP highly correlated with the values obtained with the other approaches. Compared to other objective measures, sHFP also showed the lowest variability and the best fit with a quadratic trend (r2 = 0.71) of lens density increase as a function of age. The sHFP technique offers a practical, reliable, and accurate method to measure lens density in vivo and predict lens transmittance over the visible spectrum. An accurate quantification of lens transmittance should be obtained in clinical practice, but also in research in visual and nonvisual photoreception.

Multi-species coexistence in Lotka-Volterra competitive systems with crowding effects.

PubMed

Gavina, Maica Krizna A; Tahara, Takeru; Tainaka, Kei-Ichi; Ito, Hiromu; Morita, Satoru; Ichinose, Genki; Okabe, Takuya; Togashi, Tatsuya; Nagatani, Takashi; Yoshimura, Jin

2018-01-19

Classical Lotka-Volterra (LV) competition equation has shown that coexistence of competitive species is only possible when intraspecific competition is stronger than interspecific competition, i.e., the species inhibit their own growth more than the growth of the other species. Note that density effect is assumed to be linear in a classical LV equation. In contrast, in wild populations we can observed that mortality rate often increases when population density is very high, known as crowding effects. Under this perspective, the aggregation models of competitive species have been developed, adding the additional reduction in growth rates at high population densities. This study shows that the coexistence of a few species is promoted. However, an unsolved question is the coexistence of many competitive species often observed in natural communities. Here, we build an LV competition equation with a nonlinear crowding effect. Our results show that under a weak crowding effect, stable coexistence of many species becomes plausible, unlike the previous aggregation model. An analysis indicates that increased mortality rate under high density works as elevated intraspecific competition leading to the coexistence. This may be another mechanism for the coexistence of many competitive species leading high species diversity in nature.

On hydrodynamic phase field models for binary fluid mixtures

NASA Astrophysics Data System (ADS)

Yang, Xiaogang; Gong, Yuezheng; Li, Jun; Zhao, Jia; Wang, Qi

2018-05-01

Two classes of thermodynamically consistent hydrodynamic phase field models have been developed for binary fluid mixtures of incompressible viscous fluids of possibly different densities and viscosities. One is quasi-incompressible, while the other is incompressible. For the same binary fluid mixture of two incompressible viscous fluid components, which one is more appropriate? To answer this question, we conduct a comparative study in this paper. First, we visit their derivation, conservation and energy dissipation properties and show that the quasi-incompressible model conserves both mass and linear momentum, while the incompressible one does not. We then show that the quasi-incompressible model is sensitive to the density deviation of the fluid components, while the incompressible model is not in a linear stability analysis. Second, we conduct a numerical investigation on coarsening or coalescent dynamics of protuberances using the two models. We find that they can predict quite different transient dynamics depending on the initial conditions and the density difference although they predict essentially the same quasi-steady results in some cases. This study thus cast a doubt on the applicability of the incompressible model to describe dynamics of binary mixtures of two incompressible viscous fluids especially when the two fluid components have a large density deviation.

Age or stage structure? A comparison of dynamic outcomes from discrete age- and stage-structured population models.

PubMed

Wikan, Arild

2012-06-01

Discrete stage-structured density-dependent and discrete age-structured density-dependent population models are considered. Regarding the former, we prove that the model at hand is permanent (i.e., that the population will neither go extinct nor exhibit explosive oscillations) and given density dependent fecundity terms we also show that species with delayed semelparous life histories tend to be more stable than species which possess precocious semelparous life histories. Moreover, our findings together with results obtained from other stage-structured models seem to illustrate a fairly general ecological principle, namely that iteroparous species are more stable than semelparous species. Our analysis of various age-structured models does not necessarily support the conclusions above. In fact, species with precocious life histories now appear to possess better stability properties than species with delayed life histories, especially in the iteroparous case. We also show that there are dynamical outcomes from semelparous age-structured models which we are not able to capture in corresponding stage-structured cases. Finally, both age- and stage-structured population models may generate periodic dynamics of low period (either exact or approximate). The important prerequisite is to assume density-dependent survival probabilities.

Hot electron inelastic scattering and transmission across graphene surfaces

NASA Astrophysics Data System (ADS)

Kong, Byoung Don; Champlain, James G.; Boos, J. Brad

2017-06-01

Inelastic scattering and transmission of externally injected hot carriers across graphene layers are considered as a function of graphene carrier density, temperature, and surrounding dielectric media. A finite temperature dynamic dielectric function for graphene for an arbitrary momentum q and frequency ω is found under the random phase approximation and a generalized scattering lifetime formalism is used to calculate the scattering and transmission rates. Unusual trends in scattering are found, including declining rates as graphene carrier density increases and interband transition excitations, which highlights the difference with out-of-plane as compared to in-plane transport. The results also show strong temperature dependence with a drastic increase in scattering at room temperature. The calculated scattering rate at T = 300 K shows a wide variation from 0.2 to 10 fs-1 depending on graphene carrier density, incident carrier momentum, and surrounding dielectrics. The analysis suggests that a transmission rate greater than 0.9 for a carrier with kinetic energy over 1 eV is achievable by carefully controlling the graphene carrier density in conjunction with the use of high-κ dielectric materials. Potential applications to electronic and electro-optical devices are also discussed.

Simplified large African carnivore density estimators from track indices.

PubMed

Winterbach, Christiaan W; Ferreira, Sam M; Funston, Paul J; Somers, Michael J

2016-01-01

The range, population size and trend of large carnivores are important parameters to assess their status globally and to plan conservation strategies. One can use linear models to assess population size and trends of large carnivores from track-based surveys on suitable substrates. The conventional approach of a linear model with intercept may not intercept at zero, but may fit the data better than linear model through the origin. We assess whether a linear regression through the origin is more appropriate than a linear regression with intercept to model large African carnivore densities and track indices. We did simple linear regression with intercept analysis and simple linear regression through the origin and used the confidence interval for ß in the linear model y  =  αx  + ß, Standard Error of Estimate, Mean Squares Residual and Akaike Information Criteria to evaluate the models. The Lion on Clay and Low Density on Sand models with intercept were not significant ( P  > 0.05). The other four models with intercept and the six models thorough origin were all significant ( P  < 0.05). The models using linear regression with intercept all included zero in the confidence interval for ß and the null hypothesis that ß = 0 could not be rejected. All models showed that the linear model through the origin provided a better fit than the linear model with intercept, as indicated by the Standard Error of Estimate and Mean Square Residuals. Akaike Information Criteria showed that linear models through the origin were better and that none of the linear models with intercept had substantial support. Our results showed that linear regression through the origin is justified over the more typical linear regression with intercept for all models we tested. A general model can be used to estimate large carnivore densities from track densities across species and study areas. The formula observed track density = 3.26 × carnivore density can be used to estimate densities of large African carnivores using track counts on sandy substrates in areas where carnivore densities are 0.27 carnivores/100 km 2 or higher. To improve the current models, we need independent data to validate the models and data to test for non-linear relationship between track indices and true density at low densities.

Blobs and drift wave dynamics

DOE PAGES

Zhang, Yanzeng; Krasheninnikov, S. I.

2017-09-29

The modified Hasegawa-Mima equation retaining all nonlinearities is investigated from the point of view of the formation of blobs. The linear analysis shows that the amplitude of the drift wave packet propagating in the direction of decreasing background plasma density increases and eventually saturates due to nonlinear effects. Nonlinear modification of the time averaged plasma density profile results in the formation of large amplitude modes locked in the radial direction, but still propagating in the poloidal direction, which resembles the experimentally observed chain of blobs propagating in the poloidal direction. Such specific density profiles, causing the locking of drift waves,more » could form naturally at the edge of tokamak due to a neutral ionization source. Thus, locked modes can grow in situ due to plasma instabilities, e.g., caused by finite resistivity. Furthermore, the modulation instability (in the poloidal direction) of these locked modes can result in a blob-like burst of plasma density.« less

Optimal Base Station Density of Dense Network: From the Viewpoint of Interference and Load.

PubMed

Feng, Jianyuan; Feng, Zhiyong

2017-09-11

Network densification is attracting increasing attention recently due to its ability to improve network capacity by spatial reuse and relieve congestion by offloading. However, excessive densification and aggressive offloading can also cause the degradation of network performance due to problems of interference and load. In this paper, with consideration of load issues, we study the optimal base station density that maximizes the throughput of the network. The expected link rate and the utilization ratio of the contention-based channel are derived as the functions of base station density using the Poisson Point Process (PPP) and Markov Chain. They reveal the rules of deployment. Based on these results, we obtain the throughput of the network and indicate the optimal deployment density under different network conditions. Extensive simulations are conducted to validate our analysis and show the substantial performance gain obtained by the proposed deployment scheme. These results can provide guidance for the network densification.

The difference between two random mixed quantum states: exact and asymptotic spectral analysis

NASA Astrophysics Data System (ADS)

Mejía, José; Zapata, Camilo; Botero, Alonso

2017-01-01

We investigate the spectral statistics of the difference of two density matrices, each of which is independently obtained by partially tracing a random bipartite pure quantum state. We first show how a closed-form expression for the exact joint eigenvalue probability density function for arbitrary dimensions can be obtained from the joint probability density function of the diagonal elements of the difference matrix, which is straightforward to compute. Subsequently, we use standard results from free probability theory to derive a relatively simple analytic expression for the asymptotic eigenvalue density (AED) of the difference matrix ensemble, and using Carlson’s theorem, we obtain an expression for its absolute moments. These results allow us to quantify the typical asymptotic distance between the two random mixed states using various distance measures; in particular, we obtain the almost sure asymptotic behavior of the operator norm distance and the trace distance.

Evidence of a High Density Population of Harvested Leopards in a Montane Environment

PubMed Central

Chase Grey, Julia N.; Kent, Vivien T.; Hill, Russell A.

2013-01-01

Populations of large carnivores can persist in mountainous environments following extensive land use change and the conversion of suitable habitat for agriculture and human habitation in lower lying areas of their range. The significance of these populations is poorly understood, however, and little attention has focussed on why certain mountainous areas can hold high densities of large carnivores and what the conservation implications of such populations might be. Here we use the leopard (Panthera pardus) population in the western Soutpansberg Mountains, South Africa, as a model system and show that montane habitats can support high numbers of leopards. Spatially explicit capture-recapture (SECR) analysis recorded the highest density of leopards reported outside of state-protected areas in sub-Saharan Africa. This density represents a temporally high local abundance of leopards and we explore the explanations for this alongside some of the potential conservation implications. PMID:24349375

Electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter system*

PubMed Central

Zan, Peng; Yang, Bang-hua; Shao, Yong; Yan, Guo-zheng; Liu, Hua

2010-01-01

This paper reports on the electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter. The coupling coils and human tissues, including the skin, fat, muscle, liver, and blood, were considered. Specific absorption rate (SAR) and current density were analyzed by a finite-length solenoid model. First, SAR and current density as a function of frequency (10–107 Hz) for an emission current of 1.5 A were calculated under different tissue thickness. Then relations between SAR, current density, and five types of tissues under each frequency were deduced. As a result, both the SAR and current density were below the basic restrictions of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The results show that the analysis of these data is very important for developing the artificial anal sphincter system. PMID:21121071

Electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter system.

PubMed

Zan, Peng; Yang, Bang-hua; Shao, Yong; Yan, Guo-zheng; Liu, Hua

2010-12-01

This paper reports on the electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter. The coupling coils and human tissues, including the skin, fat, muscle, liver, and blood, were considered. Specific absorption rate (SAR) and current density were analyzed by a finite-length solenoid model. First, SAR and current density as a function of frequency (10-10(7) Hz) for an emission current of 1.5 A were calculated under different tissue thickness. Then relations between SAR, current density, and five types of tissues under each frequency were deduced. As a result, both the SAR and current density were below the basic restrictions of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The results show that the analysis of these data is very important for developing the artificial anal sphincter system.

Analysis of a terminal landing on Mars

NASA Astrophysics Data System (ADS)

Tuckness, Dan G.

1995-01-01

This study consists of a preliminary performance and sensitivity assessment of trajectory and guidance capabilities of a Mars terminal landing phase. The phase begins with the end of the entry phase, which is at parachute deployment. Therefore, the trajectory investigated in this study starts at parachute deployment and continues through parachute jettison and finally propulsive deceleration and maneuvering to a specified landing site. Various landing navigation maneuver schemes and environmental conditions for the lander are investigated and their performance analyzed. Effects of atmospheric density and surface wind deviations on landing guidance are investigated using stochastic wind and density models. Simulation shows that the lander guidance is robust to wind and density dispersions. Density dispersions are found to be more critical for a precision landing than wind dispersions. Also, because of the aerodynamic characteristics of current aeroshell vehicle designs, very little terminal maneuvering is allowed for navigation.

Controlling the ripple density and heights: a new way to improve the electrical performance of CVD-grown graphene.

PubMed

Park, Won-Hwa; Jo, Insu; Hong, Byung Hee; Cheong, Hyeonsik

2016-05-14

We report a new way to enhance the electrical performances of large area CVD-grown graphene through controlling the ripple density and heights after transfer onto SiO2/Si substrates by employing different cooling rates during fabrication. We find that graphene films prepared with a high cooling rate have reduced ripple density and heights and improved electrical characteristics such as higher electron/hole mobilities as well as reduced sheet resistance. The corresponding Raman analysis also shows a significant decrease of the defects when a higher cooling rate is employed. We suggest a model that explains the improved morphology of the graphene film obtained with higher cooling rates. From these points of view, we can suggest a new pathway toward a relatively lower density and heights of ripples in order to reduce the flexural phonon-electron scattering effect, leading to higher lateral carrier mobilities.

Intrascleral outflow after deep sclerectomy with absorbable and non-absorbable implants in the rabbit eye.

PubMed

Kałużny, Jakub J; Grzanka, Dariusz; Wiśniewska, Halina; Niewińska, Alicja; Kałużny, Bartłomiej J; Grzanka, Alina

2012-10-01

The purpose of the study is an analysis of intrascleral drainage vessels formed in rabbits' eyes after non-penetrating deep sclerectomy (NPDS) with absorbable and non-absorbable implants, and comparison to eyes in which surgery was performed without implanted material. NPDS was carried out in 12 rabbits, with implantation of non-absorbable methacrylic hydrogel (N=10 eyes) or absorbable cross-linked sodium hyaluronate (N=6 eyes), or without any implant (N=8 eyes). All the animals were euthanized 1 year after surgery. Twenty-one eyeballs were prepared for light microscopy and 3 were prepared for transmission electron microscope (TEM) analysis. Aqueous humour pathways were stained with ferritin in 6 eyeballs. By light microscopy, small vessels adjacent to the areas of scarring were the most common abnormality. Vessel density was significantly higher in operated sclera compared to normal, healthy tissue, regardless of the type of implant used. The average vessel densities were 2.18±1.48 vessels/mm2 in non-implanted sclera, 2.34±1.69 vessels/mm2 in eyes with absorbable implants, and 3.64±1.78 vessels/mm2 in eyes with non-absorbable implants. Analysis of iron distribution in ferritin-injected eyes showed a positive reaction inside new aqueous draining vessels in all groups. TEM analysis showed that the ultrastructure of new vessels matched the features of the small veins. Aqueous outflow after NPDS can be achieved through the newly formed network of small intrascleral veins. Use of non-absorbable implants significantly increases vessel density in the sclera adjacent to implanted material compared to eyes in which absorbable implants or no implants were used.

Spatiotemporal characteristics of elderly population’s traffic accidents in Seoul using space-time cube and space-time kernel density estimation

PubMed Central

Cho, Nahye; Son, Serin

2018-01-01

The purpose of this study is to analyze how the spatiotemporal characteristics of traffic accidents involving the elderly population in Seoul are changing by time period. We applied kernel density estimation and hotspot analyses to analyze the spatial characteristics of elderly people’s traffic accidents, and the space-time cube, emerging hotspot, and space-time kernel density estimation analyses to analyze the spatiotemporal characteristics. In addition, we analyzed elderly people’s traffic accidents by dividing cases into those in which the drivers were elderly people and those in which elderly people were victims of traffic accidents, and used the traffic accidents data in Seoul for 2013 for analysis. The main findings were as follows: (1) the hotspots for elderly people’s traffic accidents differed according to whether they were drivers or victims. (2) The hourly analysis showed that the hotspots for elderly drivers’ traffic accidents are in specific areas north of the Han River during the period from morning to afternoon, whereas the hotspots for elderly victims are distributed over a wide area from daytime to evening. (3) Monthly analysis showed that the hotspots are weak during winter and summer, whereas they are strong in the hiking and climbing areas in Seoul during spring and fall. Further, elderly victims’ hotspots are more sporadic than elderly drivers’ hotspots. (4) The analysis for the entire period of 2013 indicates that traffic accidents involving elderly people are increasing in specific areas on the north side of the Han River. We expect the results of this study to aid in reducing the number of traffic accidents involving elderly people in the future. PMID:29768453

Spatiotemporal characteristics of elderly population's traffic accidents in Seoul using space-time cube and space-time kernel density estimation.

PubMed

Kang, Youngok; Cho, Nahye; Son, Serin

2018-01-01

The purpose of this study is to analyze how the spatiotemporal characteristics of traffic accidents involving the elderly population in Seoul are changing by time period. We applied kernel density estimation and hotspot analyses to analyze the spatial characteristics of elderly people's traffic accidents, and the space-time cube, emerging hotspot, and space-time kernel density estimation analyses to analyze the spatiotemporal characteristics. In addition, we analyzed elderly people's traffic accidents by dividing cases into those in which the drivers were elderly people and those in which elderly people were victims of traffic accidents, and used the traffic accidents data in Seoul for 2013 for analysis. The main findings were as follows: (1) the hotspots for elderly people's traffic accidents differed according to whether they were drivers or victims. (2) The hourly analysis showed that the hotspots for elderly drivers' traffic accidents are in specific areas north of the Han River during the period from morning to afternoon, whereas the hotspots for elderly victims are distributed over a wide area from daytime to evening. (3) Monthly analysis showed that the hotspots are weak during winter and summer, whereas they are strong in the hiking and climbing areas in Seoul during spring and fall. Further, elderly victims' hotspots are more sporadic than elderly drivers' hotspots. (4) The analysis for the entire period of 2013 indicates that traffic accidents involving elderly people are increasing in specific areas on the north side of the Han River. We expect the results of this study to aid in reducing the number of traffic accidents involving elderly people in the future.

Optimization and Analysis of a U-Shaped Linear Piezoelectric Ultrasonic Motor Using Longitudinal Transducers

PubMed Central

Yu, Hongpeng; Quan, Qiquan; Tian, Xinqi; Li, He

2018-01-01

A novel U-shaped piezoelectric ultrasonic motor that mainly focused on miniaturization and high power density was proposed, fabricated, and tested in this work. The longitudinal vibrations of the transducers were excited to form the elliptical movements on the driving feet. Finite element method (FEM) was used for design and analysis. The resonance frequencies of the selected vibration modes were tuned to be very close to each other with modal analysis and the movement trajectories of the driving feet were gained with transient simulation. The vibration modes and the mechanical output abilities were tested to evaluate the proposed motor further by a prototype. The maximum output speed was tested to be 416 mm/s, the maximum thrust force was 21 N, and the maximum output power was 5.453 W under frequency of 29.52 kHz and voltage of 100 Vrms. The maximum output power density of the prototype reached 7.59 W/kg, which was even greater than a previous similar motor under the exciting voltage of 200 Vrms. The proposed motor showed great potential for linear driving of large thrust force and high power density. PMID:29518963

The Predictive Effects of Early Pregnancy Lipid Profiles and Fasting Glucose on the Risk of Gestational Diabetes Mellitus Stratified by Body Mass Index.

PubMed

Wang, Chen; Zhu, Weiwei; Wei, Yumei; Su, Rina; Feng, Hui; Lin, Li; Yang, Huixia

2016-01-01

This study aimed at evaluating the predictive effects of early pregnancy lipid profiles and fasting glucose on the risk of gestational diabetes mellitus (GDM) in patients stratified by prepregnancy body mass index (p-BMI) and to determine the optimal cut-off values of each indicator for different p-BMI ranges. A retrospective system cluster sampling survey was conducted in Beijing during 2013 and a total of 5,265 singleton pregnancies without prepregnancy diabetes were included. The information for each participant was collected individually using questionnaires and medical records. Logistic regression analysis and receiver operator characteristics analysis were used in the analysis. Outcomes showed that potential markers for the prediction of GDM include early pregnancy lipid profiles (cholesterol, triacylglycerols, low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratios [LDL-C/HDL-C], and triglyceride to high-density lipoprotein cholesterol ratios [TG/HDL-C]) and fasting glucose, of which fasting glucose level was the most accurate indicator. Furthermore, the predictive effects and cut-off values for these factors varied according to p-BMI. Thus, p-BMI should be a consideration for the risk assessment of pregnant patients for GDM development.

Spectroscopic studies (FT-IR, FT-Raman, UV-Visible), normal co-ordinate analysis, first-order hyperpolarizability and HOMO, LUMO studies of 3,4-dichlorobenzophenone by using Density Functional Methods.

PubMed

Venkata Prasad, K; Samatha, K; Jagadeeswara Rao, D; Santhamma, C; Muthu, S; Mark Heron, B

2015-01-01

The vibrational frequencies of 3,4-dichlorobenzophenone (DCLBP) were obtained from the FT-IR and Raman spectral data, and evaluated based on the Density Functional Theory using the standard method B3LYP with 6-311+G(d,p) as the basis set. On the basis of potential energy distribution together with the normal-co-ordinate analysis and following the scaled quantum mechanical force methodology, the assignments for the various frequencies were described. The values of the electric dipole moment (μ) and the first-order hyperpolarizability (β) of the molecule were computed. The UV-absorption spectrum was also recorded to study the electronic transitions. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The NBO analysis, to study the intramolecular hyperconjugative interactions, was carried out. Mulliken's net charges were evaluated. The MEP and thermodynamic properties were also calculated. The electron density-based local reactivity descriptor, such as Fukui functions, was calculated to explain the chemical selectivity or reactivity site in 3,4-dichlorobenzophenone. Copyright © 2015 Elsevier B.V. All rights reserved.

Optimization and Analysis of a U-Shaped Linear Piezoelectric Ultrasonic Motor Using Longitudinal Transducers.

PubMed

Yu, Hongpeng; Quan, Qiquan; Tian, Xinqi; Li, He

2018-03-07

A novel U-shaped piezoelectric ultrasonic motor that mainly focused on miniaturization and high power density was proposed, fabricated, and tested in this work. The longitudinal vibrations of the transducers were excited to form the elliptical movements on the driving feet. Finite element method (FEM) was used for design and analysis. The resonance frequencies of the selected vibration modes were tuned to be very close to each other with modal analysis and the movement trajectories of the driving feet were gained with transient simulation. The vibration modes and the mechanical output abilities were tested to evaluate the proposed motor further by a prototype. The maximum output speed was tested to be 416 mm/s, the maximum thrust force was 21 N, and the maximum output power was 5.453 W under frequency of 29.52 kHz and voltage of 100 V rms . The maximum output power density of the prototype reached 7.59 W/kg, which was even greater than a previous similar motor under the exciting voltage of 200 V rms . The proposed motor showed great potential for linear driving of large thrust force and high power density.

Yellow fever disease: density equalizing mapping and gender analysis of international research output

PubMed Central

2013-01-01

Background A number of scientific papers on yellow fever have been published but no broad scientometric analysis on the published research of yellow fever has been reported. The aim of the article based study was to provide an in-depth evaluation of the yellow fever field using large-scale data analysis and employment of bibliometric indicators of production and quantity. Methods Data were retrieved from the Web of Science database (WoS) and analyzed as part of the NewQis platform. Then data were extracted from each file, transferred to databases and visualized as diagrams. Partially by means of density-equalizing mapping makes the findings clear and emphasizes the output of the analysis. Results In the study period from 1900 to 2012 a total of 5,053 yellow fever-associated items were published by 79 countries. The United States (USA) having the highest publication rate at 42% (n = 751) followed by far from Brazil (n = 203), France (n = 149) and the United Kingdom (n = 113). The most productive journals are the “Public Health Reports”, the “American Journal of Tropical Medicine and Hygiene” and the “Journal of Virology”. The gender analysis showed an overall steady increase of female authorship from 1950 to 2011. Brazil is the only country of the five most productive countries with a higher proportion of female scientists. Conclusions The present data shows an increase in research productivity over the entire study period, in particular an increase of female scientists. Brazil shows a majority of female authors, a fact that is confirmed by other studies. PMID:24245856

Yellow fever disease: density equalizing mapping and gender analysis of international research output.

PubMed

Bundschuh, Matthias; Groneberg, David A; Klingelhoefer, Doris; Gerber, Alexander

2013-11-18

A number of scientific papers on yellow fever have been published but no broad scientometric analysis on the published research of yellow fever has been reported.The aim of the article based study was to provide an in-depth evaluation of the yellow fever field using large-scale data analysis and employment of bibliometric indicators of production and quantity. Data were retrieved from the Web of Science database (WoS) and analyzed as part of the NewQis platform. Then data were extracted from each file, transferred to databases and visualized as diagrams. Partially by means of density-equalizing mapping makes the findings clear and emphasizes the output of the analysis. In the study period from 1900 to 2012 a total of 5,053 yellow fever-associated items were published by 79 countries. The United States (USA) having the highest publication rate at 42% (n = 751) followed by far from Brazil (n = 203), France (n = 149) and the United Kingdom (n = 113). The most productive journals are the "Public Health Reports", the "American Journal of Tropical Medicine and Hygiene" and the "Journal of Virology". The gender analysis showed an overall steady increase of female authorship from 1950 to 2011. Brazil is the only country of the five most productive countries with a higher proportion of female scientists. The present data shows an increase in research productivity over the entire study period, in particular an increase of female scientists. Brazil shows a majority of female authors, a fact that is confirmed by other studies.

Heterotypic interactions regulate cell shape and density during color pattern formation in zebrafish.

PubMed

Mahalwar, Prateek; Singh, Ajeet Pratap; Fadeev, Andrey; Nüsslein-Volhard, Christiane; Irion, Uwe

2016-11-15

The conspicuous striped coloration of zebrafish is produced by cell-cell interactions among three different types of chromatophores: black melanophores, orange/yellow xanthophores and silvery/blue iridophores. During color pattern formation xanthophores undergo dramatic cell shape transitions and acquire different densities, leading to compact and orange xanthophores at high density in the light stripes, and stellate, faintly pigmented xanthophores at low density in the dark stripes. Here, we investigate the mechanistic basis of these cell behaviors in vivo, and show that local, heterotypic interactions with dense iridophores regulate xanthophore cell shape transition and density. Genetic analysis reveals a cell-autonomous requirement of gap junctions composed of Cx41.8 and Cx39.4 in xanthophores for their iridophore-dependent cell shape transition and increase in density in light-stripe regions. Initial melanophore-xanthophore interactions are independent of these gap junctions; however, subsequently they are also required to induce the acquisition of stellate shapes in xanthophores of the dark stripes. In summary, we conclude that, whereas homotypic interactions regulate xanthophore coverage in the skin, their cell shape transitions and density is regulated by gap junction-mediated, heterotypic interactions with iridophores and melanophores. © 2016. Published by The Company of Biologists Ltd.

Process controls for improving bioleaching performance of both Li and Co from spent lithium ion batteries at high pulp density and its thermodynamics and kinetics exploration.

PubMed

Niu, Zhirui; Zou, Yikan; Xin, Baoping; Chen, Shi; Liu, Changhao; Li, Yuping

2014-08-01

Release of Co and Li from spent lithium ion batteries (LIBs) by bioleaching has attracted growing attentions. However, the pulp density was only 1% or lower, meaning that a huge quantity of media was required for bioleaching. In this work, bioleaching behavior of the spent LIBs at pulp densities ranging from 1% to 4% was investigated and process controls to improve bioleaching performance at pulp density of 2% were explored. The results showed that the pulp density exerted a considerable influence on leaching performance of Co and Li. The bioleaching efficiency decreased respectively from 52% to 10% for Co and from 80% to 37% for Li when pulp density rose from 1% to 4%. However, the maximum extraction efficiency of 89% for Li and 72% for Co was obtained at pulp density of 2% by process controls. Bioleaching of the spent LIBs has much greater potential to occur than traditional chemical leaching based on thermodynamics analysis. The product layer diffusion model described best bioleaching behavior of Co and Li. Copyright © 2014 Elsevier Ltd. All rights reserved.

Population dynamics, structure and behavior of Anopheles darlingi in a rural settlement in the Amazon rainforest of Acre, Brazil.

PubMed

Moutinho, Paulo Rufalco; Gil, Luis Herman Soares; Cruz, Rafael Bastos; Ribolla, Paulo Eduardo Martins

2011-06-24

Anopheles darlingi is the major vector of malaria in South America, and its behavior and distribution has epidemiological importance to biomedical research. In Brazil, An. darlingi is found in the northern area of the Amazon basin, where 99.5% of the disease is reported. The study area, known as Ramal do Granada, is a rural settlement inside the Amazon basin in the state of Acre. Population variations and density have been analysed by species behaviour, and molecular analysis has been measured by ND4 mitochondrial gene sequencing. The results show higher density in collections near a recent settlement, suggesting that a high level of colonization decreases the vector presence. The biting activity showed higher activity at twilight and major numbers of mosquitos in the remaining hours of the night in months of high density. From a sample of 110 individual mosquitoes, 18 different haplotypes were presented with a diversity index of 0.895, which is higher than that found in other Anopheles studies. An. darlingi depends on forested regions for their larval and adult survival. In months with higher population density, the presence of mosquitoes persisted in the second part of the night, increasing the vector capacity of the species. Despite the intra-population variation in the transition to rainy season, the seasonal distribution of haplotypes shows no change in the structure population of An. darlingi.

Investigation of vapor-deposited amorphous ice and irradiated ice by molecular dynamics simulation.

PubMed

Guillot, Bertrand; Guissani, Yves

2004-03-01

With the purpose of clarifying a number of points raised in the experimental literature, we investigate by molecular dynamics simulation the thermodynamics, the structure and the vibrational properties of vapor-deposited amorphous ice (ASW) as well as the phase transformations experienced by crystalline and vitreous ice under ion bombardment. Concerning ASW, we have shown that by changing the conditions of the deposition process, it is possible to form either a nonmicroporous amorphous deposit whose density (approximately 1.0 g/cm3) is essentially invariant with the temperature of deposition, or a microporous sample whose density varies drastically upon temperature annealing. We find that ASW is energetically different from glassy water except at the glass transition temperature and above. Moreover, the molecular dynamics simulation shows no evidence for the formation of a high-density phase when depositing water molecules at very low temperature. In order to model the processing of interstellar ices by cosmic ray protons and heavy ions coming from the magnetospheric radiation environment around the giant planets, we bombarded samples of vitreous ice and cubic ice with 35 eV water molecules. After irradiation the recovered samples were found to be densified, the lower the temperature, the higher the density of the recovered sample. The analysis of the structure and vibrational properties of this new high-density phase of amorphous ice shows a close relationship with those of high-density amorphous ice obtained by pressure-induced amorphization. Copyright 2004 American Institute of Physics

Estimating the settling velocity of bioclastic sediment using common grain-size analysis techniques

USGS Publications Warehouse

Cuttler, Michael V. W.; Lowe, Ryan J.; Falter, James L.; Buscombe, Daniel D.

2017-01-01

Most techniques for estimating settling velocities of natural particles have been developed for siliciclastic sediments. Therefore, to understand how these techniques apply to bioclastic environments, measured settling velocities of bioclastic sedimentary deposits sampled from a nearshore fringing reef in Western Australia were compared with settling velocities calculated using results from several common grain-size analysis techniques (sieve, laser diffraction and image analysis) and established models. The effects of sediment density and shape were also examined using a range of density values and three different models of settling velocity. Sediment density was found to have a significant effect on calculated settling velocity, causing a range in normalized root-mean-square error of up to 28%, depending upon settling velocity model and grain-size method. Accounting for particle shape reduced errors in predicted settling velocity by 3% to 6% and removed any velocity-dependent bias, which is particularly important for the fastest settling fractions. When shape was accounted for and measured density was used, normalized root-mean-square errors were 4%, 10% and 18% for laser diffraction, sieve and image analysis, respectively. The results of this study show that established models of settling velocity that account for particle shape can be used to estimate settling velocity of irregularly shaped, sand-sized bioclastic sediments from sieve, laser diffraction, or image analysis-derived measures of grain size with a limited amount of error. Collectively, these findings will allow for grain-size data measured with different methods to be accurately converted to settling velocity for comparison. This will facilitate greater understanding of the hydraulic properties of bioclastic sediment which can help to increase our general knowledge of sediment dynamics in these environments.

Dislocation, crystallite size distribution and lattice strain of magnesium oxide nanoparticles

NASA Astrophysics Data System (ADS)

Sutapa, I. W.; Wahid Wahab, Abdul; Taba, P.; Nafie, N. L.

2018-03-01

The oxide of magnesium nanoparticles synthesized using sol-gel method and analysis of the structural properties was conducted. The functional groups of nanoparticles has been analysed by Fourier Transform Infrared Spectroscopy (FT-IR). Dislocations, average size of crystal, strain, stress, the energy density of crystal, crystallite size distribution and morphologies of the crystals were determined based on X-ray diffraction profile analysis. The morphological of the crystal was analysed based on the image resulted from SEM analysis. The crystallite size distribution was calculated with the contention that the particle size has a normal logarithmic form. The most orientations of crystal were determined based on the textural crystal from diffraction data of X-ray diffraction profile analysis. FT-IR results showed the stretching vibration mode of the Mg-O-Mg in the range of 400.11-525 cm-1 as a broad band. The average size crystal of nanoparticles resulted is 9.21 mm with dislocation value of crystal is 0.012 nm-2. The strains, stress, the energy density of crystal are 1.5 x 10-4 37.31 MPa; 0.72 MPa respectively. The highest texture coefficient value of the crystal is 0.98. This result is supported by morphological analysis using SEM which shows most of the regular cubic-shaped crystals. The synthesis method is suitable for simple and cost-effective synthesis model of MgO nanoparticles.

The Transport of Density Fluctuations Throughout the Heliosphere

NASA Technical Reports Server (NTRS)

Zank, G. P.; Jetha, N.; Hu, Q.; Hunana, P.

2012-01-01

The solar wind is recognized as a turbulent magnetofluid, for which the properties of the turbulent velocity and magnetic field fluctuations are often described by the equations of incompressible magnetohydrodynamics (MHD). However, low-frequency density turbulence is also ubiquitous. On the basis of a nearly incompressible formulation of MHD in the expanding inhomogeneous solar wind, we derive the transport equation for the variance of the density fluctuations (Rho(exp 2)). The transport equation shows that density fluctuations behave as a passive scalar in the supersonic solar wind. In the absence of sources of density turbulence, such as within 1AU, the variance (Rho(exp 2)) approximates r(exp -4). In the outer heliosphere beyond 1 AU, the shear between fast and slow streams, the propagation of shocks, and the creation of interstellar pickup ions all act as sources of density turbulence. The model density fluctuation variance evolves with heliocentric distance within approximately 300 AU as (Rho(exp 2)) approximates r(exp -3.3) after which it flattens and then slowly increases. This is precisely the radial profile for the density fluctuation variance observed by Voyager 2. Using a different analysis technique, we confirm the radial profile for Rho(exp 2) of Bellamy, Cairns, & Smith using Voyager 2 data. We conclude that a passive scalar description for density fluctuations in the supersonic solar wind can explain the density fluctuation variance observed in both the inner and the outer heliosphere.

Comparison of Boltzmann and Gibbs entropies for the analysis of single-chain phase transitions

NASA Astrophysics Data System (ADS)

Shakirov, T.; Zablotskiy, S.; Böker, A.; Ivanov, V.; Paul, W.

2017-03-01

In the last 10 years, flat histogram Monte Carlo simulations have contributed strongly to our understanding of the phase behavior of simple generic models of polymers. These simulations result in an estimate for the density of states of a model system. To connect this result with thermodynamics, one has to relate the density of states to the microcanonical entropy. In a series of publications, Dunkel, Hilbert and Hänggi argued that it would lead to a more consistent thermodynamic description of small systems, when one uses the Gibbs definition of entropy instead of the Boltzmann one. The latter is the logarithm of the density of states at a certain energy, the former is the logarithm of the integral of the density of states over all energies smaller than or equal to this energy. We will compare the predictions using these two definitions for two polymer models, a coarse-grained model of a flexible-semiflexible multiblock copolymer and a coarse-grained model of the protein poly-alanine. Additionally, it is important to note that while Monte Carlo techniques are normally concerned with the configurational energy only, the microcanonical ensemble is defined for the complete energy. We will show how taking the kinetic energy into account alters the predictions from the analysis. Finally, the microcanonical ensemble is supposed to represent a closed mechanical N-particle system. But due to Galilei invariance such a system has two additional conservation laws, in general: momentum and angular momentum. We will also show, how taking these conservation laws into account alters the results.

Quantitative analysis of the text and graphic content in ophthalmic slide presentations.

PubMed

Ing, Edsel; Celo, Erdit; Ing, Royce; Weisbrod, Lawrence; Ing, Mercedes

2017-04-01

To determine the characteristics of ophthalmic digital slide presentations. Retrospective quantitative analysis. Slide presentations from a 2015 Canadian primary eye care conference were analyzed for their duration, character and word count, font size, words per minute (wpm), lines per slide, words per slide, slides per minute (spm), text density product (wpm × spm), proportion of graphic content, and Flesch Reading Ease (FRE) score using Microsoft PowerPoint and Word. The median audience evaluation score for the lectures was used to dichotomize the higher scoring lectures (HSL) from the lower scoring lectures (LSL). A priori we hypothesized that there would be a difference in the wpm, spm, text density product, and FRE score between HSL and LSL. Wilcoxon rank-sum tests with Bonferroni correction were utilized. The 17 lectures had medians of 2.5 spm, 20.3 words per slide, 5.0 lines per slide, 28-point sans serif font, 36% graphic content, and text density product of 136.4 words × slides/minute 2 . Although not statistically significant, the HSL had more wpm, fewer words per slide, more graphics per slide, greater text density, and higher FRE score than LSL. There was a statistically significant difference in the spm of the HSL (3.1 ± 1.0) versus the LSL (2.2 ± 1.0) at p = 0.0124. All presenters showed more than 1 slide per minute. The HSL showed more spm than the LSL. The descriptive statistics from this study may aid in the preparation of slides used for teaching and conferences. Copyright © 2017 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

On The Evidence For Large-Scale Galactic Conformity In The Local Universe

NASA Astrophysics Data System (ADS)

Sin, Larry P. T.; Lilly, Simon J.; Henriques, Bruno M. B.

2017-10-01

We re-examine the observational evidence for large-scale (4 Mpc) galactic conformity in the local Universe, as presented in Kauffmann et al. We show that a number of methodological features of their analysis act to produce a misleadingly high amplitude of the conformity signal. These include a weighting in favour of central galaxies in very high density regions, the likely misclassification of satellite galaxies as centrals in the same high-density regions and the use of medians to characterize bimodal distributions. We show that the large-scale conformity signal in Kauffmann et al. clearly originates from a very small number of central galaxies in the vicinity of just a few very massive clusters, whose effect is strongly amplified by the methodological issues that we have identified. Some of these 'centrals' are likely misclassified satellites, but some may be genuine centrals showing a real conformity effect. Regardless, this analysis suggests that conformity on 4 Mpc scales is best viewed as a relatively short-range effect (at the virial radius) associated with these very large neighbouring haloes, rather than a very long-range effect (at tens of virial radii) associated with the relatively low-mass haloes that host the nominal central galaxies in the analysis. A mock catalogue constructed from a recent semi-analytic model shows very similar conformity effects to the data when analysed in the same way, suggesting that there is no need to introduce new physical processes to explain galactic conformity on 4 Mpc scales.

Grey matter alterations in patients with Pantothenate Kinase-Associated Neurodegeneration (PKAN).

PubMed

Rodriguez-Raecke, Rea; Roa-Sanchez, Pedro; Speckter, Herwin; Fermin-Delgado, Rafael; Perez-Then, Eddy; Oviedo, Jairo; Stoeter, Peter

2014-09-01

Pantothenate Kinase-Associated Neurodegeneration (PKAN) is a rare heritable disease marked by dystonia and loss of movement control. In contrast to the well-known "Eye-of-the-Tiger" sign affecting the globus pallidus, little is known about other deviations of brain morphology, especially about grey matter changes. We investigated 29 patients with PKAN and 29 age-matched healthy controls using Magnet Resonance Imaging and Voxel-Based Morphometry. As compared to controls, children with PKAN showed increased grey matter density in the putamen and nucleus caudatus and adults with PKAN showed increased grey matter density in the ventral part of the anterior cingulate cortex. A multiple regression analysis with dystonia score as predictor showed grey matter reduction in the cerebellum, posterior cingulate cortex, superior parietal lobule, pars triangularis and small frontal and temporal areas and an analysis with age as predictor showed grey matter decreases in the putamen, nucleus caudatus, supplementary motor area and anterior cingulate cortex. The grey matter increases may be regarded as a secondary phenomenon compensating the increased activity of the motor system due to a reduced inhibitory output of the globus pallidus. With increasing age, the grey matter reduction of cortical midline structures however might contribute to the progression of dystonic symptoms due to loss of this compensatory control. Copyright © 2014 Elsevier Ltd. All rights reserved.

MicroCT parameters for multimaterial elements assessment

NASA Astrophysics Data System (ADS)

de Araújo, Olga M. O.; Silva Bastos, Jaqueline; Machado, Alessandra S.; dos Santos, Thaís M. P.; Ferreira, Cintia G.; Rosifini Alves Claro, Ana Paula; Lopes, Ricardo T.

2018-03-01

Microtomography is a non-destructive testing technique for quantitative and qualitative analysis. The investigation of multimaterial elements with great difference of density can result in artifacts that degrade image quality depending on combination of additional filter. The aim of this study is the selection of parameters most appropriate for analysis of bone tissue with metallic implant. The results show the simulation with MCNPX code for the distribution of energy without additional filter, with use of aluminum, copper and brass filters and their respective reconstructed images showing the importance of the choice of these parameters in image acquisition process on computed microtomography.

Assessment of CD-105 as an Angiogenic Modulator in Odontogenic Myxomas and Dental Follicles.

PubMed

Del Carmen González-Galván, María; Aguirre-Urizar, José Manuel; Bologna-Molina, Ronell; Farfán-Morales, J Eduardo; Gainza-Cirauqui, Maria Luisa; Marichalar-Mendia, Xabier; Mosqueda-Taylor, Adalberto

2016-06-01

Aim Odontogenic myxoma is a benign intraosseous neoplasm of the jaws, with a locally aggressive behavior and a high recurrence rate. CD-105 is a homodimeric cell membrane glycoprotein and is a component of the TGF-β1 growth factor receptor complex that modulates angiogenesis by regulating the proliferation, differentiation and cellular migration. The aim of this study is to quantify the microvascular density of the odontogenic myxoma based on the expression of CD-105. Materials and Methods The analysis included 18 odontogenic myxoma and 18 dental follicles as controls. A standard immunohistochemical procedure was performed with the CD-105 antibody. Five representative fields (40×) of the odontogenic myxoma and the dental follicles were selected to determine the microvascular density, which was then followed by a descriptive and comparative statistical analysis. Results Dental follicles presented a significantly higher microvascular density compared with odontogenic myxoma (P = .001). The odontogenic myxoma smaller than 3 cm showed a greater microvascular density than those larger than 3 cm in size (P > .05), and the microvascular density was lower in large odontogenic myxomas as compared with the dental follicles (P = .003). Conclusion A weaker expression of CD-105 in odontogenic myxoma might indicate a lower angiogenic activity, suggesting that vascular proliferation has a limited role in the growth mechanisms and in the aggressive behavior of this neoplasm. © The Author(s) 2016.

Morphometric analysis of the folliculostellate cells and luteinizing hormone gonadotropic cells of the anterior pituitary of the men during the aging process.

PubMed

Čukuranović Kokoris, Jovana; Jovanović, Ivan; Pantović, Vukica; Krstić, Miljan; Stanojković, Milica; Milošević, Verica; Ugrenović, Slađana; Stojanović, Vesna

2017-02-01

The aim of this research was to quantify the changes in the morphology and density of the anterior pituitary folliculostellate (FS) and luteinizing hormone (LH) cells. Material was tissue of the pituitary gland of the 14 male cadavers. Tissue slices were immunohistochemically stained with monoclonal anti-LH antibody and polyclonal anti-S100 antibody for the detection of LH and FS cells, respectively. Digital images of the stained slices were afterwards morphometrically analyzed by ImageJ. Results of the morphometric analysis showed significant increase of the FS cells volume density in cases older than 70 years. Volume density of the LH cells did not significantly change, whereas their area significantly increased with age. Nucleocytoplasmic ratio of the LH cells gradually decreased and became significant after the age of 70. Finally, volume density of the FS cell significantly correlated with LH cells area and nucleocytoplasmic ratio. From all above cited, we concluded that in men, density and size of the FS cells increase with age. Long-term hypertrophy of the LH cells results in their functional decline after the age of 70. Strong correlation between FS cells and LH cells morphometric parameters might point to age-related interaction between these two cell groups. Copyright © 2016 Elsevier Ltd. All rights reserved.

Digital subtraction radiographic analysis of the combination of bioabsorbable membrane and bovine morphogenetic protein pool in human periodontal infrabony defects

PubMed Central

GUIMARÃES, Maria do Carmo Machado; PASSANEZI, Euloir; SANT’ANA, Adriana Campos Passanezi; GREGHI, Sebastião Luiz Aguiar; TABA JUNIOR, Mario

2010-01-01

Objectives This study assessed the bone density gain and its relationship with the periodontal clinical parameters in a case series of a regenerative therapy procedure. Material and Methods Using a split-mouth study design, 10 pairs of infrabony defects from 15 patients were treated with a pool of bovine bone morphogenetic proteins associated with collagen membrane (test sites) or collagen membrane only (control sites). The periodontal healing was clinically and radiographically monitored for six months. Standardized presurgical and 6-month postoperative radiographs were digitized for digital subtraction analysis, which showed relative bone density gain in both groups of 0.034 ± 0.423 and 0.105 ± 0.423 in the test and control group, respectively (p>0.05). Results As regards the area size of bone density change, the influence of the therapy was detected in 2.5 mm2 in the test group and 2 mm2 in the control group (p>0.05). Additionally, no correlation was observed between the favorable clinical results and the bone density gain measured by digital subtraction radiography (p>0.05). Conclusions The findings of this study suggest that the clinical benefit of the regenerative therapy observed did not come with significant bone density gains. Long-term evaluation may lead to a different conclusions. PMID:20835573

Effect of plasma density around Io on local electron heating in the Io plasma torus

NASA Astrophysics Data System (ADS)

Tsuchiya, F.; Yoshioka, K.; Kagitani, M.; Kimura, T.; Murakami, G.; Yamazaki, A.; Misawa, H.; Kasaba, Y.; Yoshikawa, I.; Sakanoi, T.; Koga, R.; Ryo, A.; Suzuki, F.; Hikida, R.

2017-12-01

HISAKI observation of Io plasma torus (IPT) with extreme ultraviolet (EUV) wavelength range is a useful probe to access plasma environment in inner magnetosphere of Jupiter. Emissions from sulfur and oxygen ions in EUV range are caused by electron impact excitation and their intensity is well correlated with the abundance of hot electron in IPT. Previous observation showed that the brightness was enhanced downstream of the satellite Io, indicating that efficient electron heating takes place at Io and/or just downstream of Io. Detailed analysis of the emission intensity shows that the brightness depends on the magnetic longitude at Io and primary and secondary peaks appear in the longitude ranges of 100-130 and 250-340 degrees, respectively. The peak position and amplitude are slightly different between dawn and dusk sides. Here, we introduce inhomogeneous IPT density model in order to investigate relation between the emission intensity and local plasma density around Io in detail. An empirical IPT model is used for spatial distribution of ion and electron densities in the meridional plane. To include longitude and local time asymmetry in IPT, we consider (1)dawnward shift of IPT due to global convection electric field, (2) offset of Jupiter's dipole magnetic field, and (3) tilt of IPT with respect to Io's orbital plane. The modeled electron density at the position of Io as a function of magnetic longitude at Io shows similar profile with the ion emission intensity derived from the observation. This result suggests that energy extracted around Io and/or efficiency of electron heating is closely related to the plasma density around Io and longitude and local time dependences is explained by the spatial inhomogeneity of plasma density in IPT. A part of the energy extracted around Io could be transferred to the Jovian ionosphere along the magnetic field line and cause bright aurora spots and strong radio emissions.

Graphene-induced band gap renormalization in polythiophene: a many-body perturbation study

NASA Astrophysics Data System (ADS)

Marsusi, F.; Fedorov, I. A.; Gerivani, S.

2018-01-01

Density functional theory and many-body perturbation theory at the G0W0 level are employed to study the electronic properties of polythiophene (PT) adsorbed on the graphene surface. Analysis of the charge density difference shows that substrate-adsorbate interaction leads to a strong physisorption and interfacial electric dipole moment formation. The electrostatic potential displays a  -0.19 eV shift in the graphene work function from its initial value of 4.53 eV, as the result of the interaction. The LDA band gap of the polymer does not show any change. However, the band structure exhibits weak orbital hybridizations resulting from slight overlapping between the polymer and graphene states wave functions. The interfacial polarization effects on the band gap and levels alignment are investigated at the G0W0 level and show a notable reduction of PT band gap compared to that of the isolated chain.

The alterations in high density polyethylene properties with gamma irradiation

NASA Astrophysics Data System (ADS)

Zaki, M. F.; Elshaer, Y. H.; Taha, Doaa. H.

2017-10-01

In the present investigation, high density polyethylene (HDPE) polymer has been used to study the alterations in its properties under gamma-irradiation. Physico-chemical properties have been investigated with different spectroscopy techniques, Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), biocompatibility properties, as well as, mechanical properties change. The FT-IR analysis shows the formation of new band at 1716 cm-1 that is attributed to the oxidation of irradiated polymer chains, which is due to the formation of carbonyl groups (C˭O). XRD patterns show that a decrease in the crystallite size and increase in the Full Width at Half Maximum (FWHM). This means that the crystallinity of irradiated samples is decreased with increase in gamma dose. The contact angle measurements show an increase in the surface free energy as the gamma irradiation increases. The measurements of mechanical properties of irradiated HDPE samples were discussed.

Momentum transport and nonlocality in heat-flux-driven magnetic reconnection in high-energy-density plasmas

DOE PAGES

Liu, Chang; Fox, William; Bhattacharjee, Amitava; ...

2017-10-06

Recent theory has demonstrated a novel physics regime for magnetic reconnection in high-energy-density plasmas where the magnetic field is advected by heat flux via the Nernst effect. In this paper, we elucidate the physics of the electron dissipation layer in this regime. Through fully kinetic simulation and a generalized Ohm's law derived from first principles, we show that momentum transport due to a nonlocal effect, the heat-flux-viscosity, provides the dissipation mechanism for magnetic reconnection. Scaling analysis, and simulations show that the reconnection process comprises a magnetic field compression stage and quasisteady reconnection stage, and the characteristic width of the currentmore » sheet in this regime is several electron mean-free paths. Finally, these results show the important interplay between nonlocal transport effects and generation of anisotropic components to the distribution function.« less

Density, ultrasound velocity, acoustic impedance, reflection and absorption coefficient determination of liquids via multiple reflection method.

PubMed

Hoche, S; Hussein, M A; Becker, T

2015-03-01

The accuracy of density, reflection coefficient, and acoustic impedance determination via multiple reflection method was validated experimentally. The ternary system water-maltose-ethanol was used to execute a systematic, temperature dependent study over a wide range of densities and viscosities aiming an application as inline sensor in beverage industries. The validation results of the presented method and setup show root mean square errors of: 1.201E-3 g cm(-3) (±0.12%) density, 0.515E-3 (0.15%) reflection coefficient and 1.851E+3 kg s(-1) m(-2) (0.12%) specific acoustic impedance. The results of the diffraction corrected absorption showed an average standard deviation of only 0.12%. It was found that the absorption change shows a good correlation to concentration variations and may be useful for laboratory analysis of sufficiently pure liquids. The main part of the observed errors can be explained by the observed noise, temperature variation and the low signal resolution of 50 MHz. In particular, the poor signal-to-noise ratio of the second reflector echo was found to be a main accuracy limitation. Concerning the investigation of liquids the unstable properties of the reference material PMMA, due to hygroscopicity, were identified to be an additional, unpredictable source of uncertainty. While dimensional changes can be considered by adequate methodology, the impact of the time and temperature dependent water absorption on relevant reference properties like the buffer's sound velocity and density could not be considered and may explain part of the observed deviations. Copyright © 2014 Elsevier B.V. All rights reserved.

Layer structure of the Venus daytime ionosphere from Venera-15,-16 radio occultation

NASA Astrophysics Data System (ADS)

Gavrik, Anatoly

Up to now more than five hundred radio occultation experiments had been carried out by different missions to research physical properties of the Venus ionosphere. The purpose of this report is to show new properties of the Venus daytime ionosphere reanalyzing Venera-15,-16 dual-frequency occultation data. The high coherence and stability of radio signals of Venera- 15,-16 at wave lengths 32 cm and 8 cm, along with the fact, that the refractive amplification at 32 cm in the ionosphere exceeds by factor 6 the refractive amplification at 13 cm used by others researches, have allowed to perform analysis of radiophysical parameters in the Venus ionosphere more accurate. Progress in the radiovision theory and up-to-date digital processing techniques have provided an opportunity to discover unknown layered structure of the Venus daytime ionosphere. We offer the new technique of the data analysis that allows us to separate influence of noise, ionosphere and atmosphere on the radio occultation results. We point out that significant gradient variations in the vertical distribution of the electron density are observed in the region of maximum electron density of the daytime ionosphere at altitudes of 150-175 km. That testifies layered structure of this part of the Venus ionosphere. The results of data analysis reveal the regular existence of the ionospheric layers in the bottom daytime ionosphere at altitudes from 80 up to 115 km. The bottom border of the ionosphere part can vary in the range of 80-100 km, and gradients of the electron density show strong variability. We detect the wave structure in the top atmosphere and in the bottom ionosphere at altitudes from 60 up to 115 km as well. It is difficult to obtain correct electron density in the region, where we have detected the new ionospheric layers. Relative errors of the electron density are greater than 100% at altitudes between 80 and 120 km. The bottom part of the ionosphere is more variable, than overlying area of the main maximum of the daytime ionosphere. It is difficult to explain such layered structures of the Venus daytime ionosphere by means of existing model of the photochemical equilibrium.

Biodegradation of thermally treated high-density polyethylene (HDPE) by Klebsiella pneumoniae CH001.

PubMed

Awasthi, Shraddha; Srivastava, Pratap; Singh, Pardeep; Tiwary, D; Mishra, Pradeep Kumar

2017-10-01

Biodegradation of plastics, which are the potential source of environmental pollution, has received a great deal of attention in the recent years. We aim to screen, identify, and characterize a bacterial strain capable of degrading high-density polyethylene (HDPE). In the present study, we studied HDPE biodegradation using a laboratory isolate, which was identified as Klebsiella pneumoniae CH001 (Accession No MF399051). The HDPE film was characterized by Universal Tensile Machine (UTM), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Atomic Force Microscope (AFM) before and after microbial incubation. We observed that this strain was capable of adhering strongly on HDPE surface and form a thick biofilm, when incubated in nutrient broth at 30 °C on 120 rpm for 60 days. UTM analysis showed a significant decrease in weight (18.4%) and reduction in tensile strength (60%) of HDPE film. Furthermore, SEM analysis showed the cracks on the HDPE surface, whereas AFM results showed an increase in surface roughness after bacterial incubation. Overall, these results indicate that K. pneumoniae CH001 can be used as potential candidate for HDPE degradation in eco-friendly and sustainable manner in the environment.

Pressure-induced ferroelectric to paraelectric transition in LiTaO 3 and (Li,Mg)TaO 3

DOE PAGES

Yamanaka, Takamitsu; Nakamoto, Yuki; Takei, Fumihiko; ...

2016-02-16

X-ray powder diffraction and Raman scattering of LiTaO 3 (LT) and (Li,Mg)TaO 3 (LMT) have been measured under pressure up to 46 GPa. Above 30 GPa, the ferroelectric rhombohedral phase (R3c, Z – 6) of LiTaO 3 transforms to a paraelectric orthorhombic phase (Pnma with Z – 4) with a large hysteresis. Rietveld profile fitting analysis shows that the Li-O bond is compressed and approaches that of Ta-O with pressure. The cation distribution analysis of the orthorhombic perovskite structure shows that Li and Ta are located in the octahedral 8-fold coordination sites. Difference Fourier |F obs(hkl)| - |F cal(hkl)| mapsmore » of LiTaO 3 and (Li,Mg)TaO 3 indicate polarization in the c axis direction and a more distinct electron density distribution around the Ta position for (Li,Mg)TaO 3 compared to LiTaO 3. The observed effective charges indicate that for (Li,Mg)TaO 3 without vacancies Ta 5+ becomes less ionized as a function of Mg substitution. Considering both site occupancy and effective charge analysis, Ta 5+ is reduced to Ta 4.13+. Mg 2+ and O 2- change to Mg 1.643+ and O 1.732 -, respectively. The space- and time-averaged structures of the dynamical vibration of atoms can be elucidated from the electron density analysis by difference Fourier and temperature factors T(hkl) in the structure refinement. The refinement of the temperature factor is consistent with the cation distribution assuming full stoichiometry. The residual electron density induced from the excess electron in (Li,Mg)TaO 3 indicates more electrons around the Ta site, as confirmed by the effective charge analysis. Raman spectra of LiTaO 3 and (Li,Mg)TaO 3 show notable changes over the measured pressure range. Raman peaks centered at 250 cm –1 and 350 cm –1 at ambient pressure merge above 8 GPa, which we associate with the diminishing of difference in distances between Li-O and Ta-O bonds with pressure in both materials. Finally, Raman spectra show significant changes at 28 GPa and 33 GPa for LT and LMT, respectively, due to the structural transition from R3c to Pnma consistent with the x-ray diffraction results.« less

Fusion of Hard and Soft Information in Nonparametric Density Estimation

DTIC Science & Technology

2015-06-10

and stochastic optimization models, in analysis of simulation output, and when instantiating probability models. We adopt a constrained maximum...particular, density estimation is needed for generation of input densities to simulation and stochastic optimization models, in analysis of simulation output...an essential step in simulation analysis and stochastic optimization is the generation of probability densities for input random variables; see for

Semi-automatic assessment of skin capillary density: proof of principle and validation.

PubMed

Gronenschild, E H B M; Muris, D M J; Schram, M T; Karaca, U; Stehouwer, C D A; Houben, A J H M

2013-11-01

Skin capillary density and recruitment have been proven to be relevant measures of microvascular function. Unfortunately, the assessment of skin capillary density from movie files is very time-consuming, since this is done manually. This impedes the use of this technique in large-scale studies. We aimed to develop a (semi-) automated assessment of skin capillary density. CapiAna (Capillary Analysis) is a newly developed semi-automatic image analysis application. The technique involves four steps: 1) movement correction, 2) selection of the frame range and positioning of the region of interest (ROI), 3) automatic detection of capillaries, and 4) manual correction of detected capillaries. To gain insight into the performance of the technique, skin capillary density was measured in twenty participants (ten women; mean age 56.2 [42-72] years). To investigate the agreement between CapiAna and the classic manual counting procedure, we used weighted Deming regression and Bland-Altman analyses. In addition, intra- and inter-observer coefficients of variation (CVs), and differences in analysis time were assessed. We found a good agreement between CapiAna and the classic manual method, with a Pearson's correlation coefficient (r) of 0.95 (P<0.001) and a Deming regression coefficient of 1.01 (95%CI: 0.91; 1.10). In addition, we found no significant differences between the two methods, with an intercept of the Deming regression of 1.75 (-6.04; 9.54), while the Bland-Altman analysis showed a mean difference (bias) of 2.0 (-13.5; 18.4) capillaries/mm(2). The intra- and inter-observer CVs of CapiAna were 2.5% and 5.6% respectively, while for the classic manual counting procedure these were 3.2% and 7.2%, respectively. Finally, the analysis time for CapiAna ranged between 25 and 35min versus 80 and 95min for the manual counting procedure. We have developed a semi-automatic image analysis application (CapiAna) for the assessment of skin capillary density, which agrees well with the classic manual counting procedure, is time-saving, and has a better reproducibility as compared to the classic manual counting procedure. As a result, the use of skin capillaroscopy is feasible in large-scale studies, which importantly extends the possibilities to perform microcirculation research in humans. © 2013.

Topside Ionospheric Response to Solar EUV Variability

NASA Astrophysics Data System (ADS)

Anderson, P. C.; Hawkins, J.

2015-12-01

We present an analysis of 23 years of thermal plasma measurements in the topside ionosphere from several DMSP spacecraft at ~800 km. The solar cycle variations of the daily averaged densities, temperatures, and H+/O+ ratios show a strong relationship to the solar EUV as described by the E10.7 solar EUV proxy with cross-correlation coefficients (CCCs) with the density greater than 0.85. The H+/O+ varies dramatically from solar maximum when it is O+ dominated to solar minimum when it is H+ dominated. These ionospheric parameters also vary strongly with season, particularly at latitudes well away from the equator where the solar zenith angle (SZA) varies greatly with season. There are strong 27-day solar rotation periodicities in the density, associated with the periodicities in the solar EUV as measured by the TIMED SEE and SDO EVE instruments, with CCCs at times greater than 0.9 at selected wavelengths. Empirical Orthogonal Function (EOF) analysis captures over 95% of the variation in the density over the 23 years in the first two principle components. The first principle component (PC1) is clearly associated with the solar EUV showing a 0.91 CCC with the E10.7 proxy while the PC1 EOFs remain relatively constant with latitude indicating that the solar EUV effects are relatively independent of latitude. The second principle component (PC2) is clearly associated with the SZA variation, showing strong correlations with the SZA and the concomitant density variations at latitudes away from the equator and with the PC2 EOFs having magnitudes near zero at the equator and maximum at high latitude. The magnitude of the variation of the response of the topside ionosphere to solar EUV variability is shown to be closely related to the composition. This is interpreted as the result of the effect of composition on the scale height in the topside ionosphere and the "pivot effect" in which the variation in density near the F2 peak is expected to be amplified by a factor of e at an altitude a scale height above the F2 peak. When the topside ionosphere is H+ dominated, DMSP may be much less than a scale height above the F2 peak while when it is O+ dominated, DMSP may be several scale heights above the F2 peak.

The Influence of Green Infrastructure on Urban Resilience in Greater London

NASA Astrophysics Data System (ADS)

Oh, Yukyung

2017-04-01

High population densities and diverse economic activities in urban areas create social issues as well as a range of environmental impacts including air pollution, soil contamination, loss of biodiversity and health problems (Alberti et al., 2003; Dobbs, Escobedo, & Zipperer, 2011; Grimm et al., 2008). The concept of urban resilience has been used for increasing the capacity of the entities and players to adapt to rapid changes, and urban green spaces play a crucial role in increasing urban resilience. Greater London has a good case for increasing urban green spaces and resilience under the London Plan. The relevance of urban open spaces and several socioeconomic indicators would provide researchers and policy makers with the information for managing green coverage. The correlation analysis of two quantitative data such as open space and socioeconomic data of Greater London was conducted with SPSS. The data for open spaces in Greater London was gained through Greenspace Information for Greater London. The data was converted from vector to raster in Geographic Information System (GIS), so as to calculate landscape metrics for open spaces in Greater London through a spatial pattern analysis program, FRAGSTATS 4.2. The socioeconomic data was obtained from "London Borough Profile", London Datastore. In addition, data on total carbon emissions from Industry and Commercial, Domestic, Transport, LULUCF Net Emissions, and per capita emissions were gained from UK local authority and regional carbon dioxide emissions national statistics: 2005-2014 released from Department of Energy and Climate Change. The indicators from open spaces are total area of open space and patch density or contagion of open spaces. The latter indicator allows to figure out the level of fragmentation of open spaces. The socioeconomic indicators cover number of jobs by workplace, jobs density, crime rates per thousand population, and several wellbeing indicators such as life satisfaction, worthwhileness, happiness and anxiety. The correlation analysis outcomes can be divided into three levels such as Greater London as a whole, and Inner and Outer London. In Greater London, total area of green spaces has a strong relation with crime rates, and a less strong relation with number of jobs. Both socioeconomic indicators showed a negative trend along with the increase of open spaces. In terms of wellbeing indicators, the positive trend of life satisfaction, worthwhileness and happiness, and the negative trend of anxiety can be found in accordance with the increase of green coverage. In Inner London, job density and crime rates show a negative trend in accordance with the increase of total open space areas. And as contagion of open spaces is higher, the indicators of number of jobs, jobs density, and crime rates also showed an increase tendency. As for worthwhileness and happiness, it also showed a substantial correlation with contagion of open spaces. In Outer London, the correlation between job density and crime rates, and open space cannot be found, but the wellbeing indicators such as life satisfaction and worthwhileness show an increase trend along with larger green coverage.

Surrogate Immiscible Liquid Solution Pairs with Refractive Indexes Matchable Over a Wide Range of Density and Viscosity Ratios

NASA Astrophysics Data System (ADS)

Saksena, Rajat; Christensen, Kenneth T.; Pearlstein, Arne J.

2014-11-01

Use of laser diagnostics in liquid-liquid flows is limited by refractive index mismatch. This can be avoided using a surrogate pair of immiscible index-matched liquids, with density and viscosity ratios matching those of the original liquid pair. We demonstrate that a wide range of density and viscosity ratios is accessible using aqueous solutions of 1,2-propanediol and CsBr (for which index, density, and viscosity are available), and solutions of light and heavy silicone oils and 1-bromooctane (for which we measured the same properties at 119 compositions). For each liquid phase, polynomials in the composition variables were fitted to index and density and to the logarithm of kinematic viscosity, and the fits were used to determine accessible density and viscosity ratios for each matchable index. Index-matched solution pairs can be prepared with density and viscosity ratios equal to those for water-liquid CO2 at 0oC over a range of pressure, and for water-crude oil and water-trichloroethylene, each over a range of temperature. For representative index-matched solutions, equilibration changes index, density, and viscosity only slightly, and chemical analysis show that no component of either solution has significant interphase solubility. Partially supported by Intl. Inst. for Carbon-Neutral Energy Research.

A Canopy Density Model for Planar Orchard Target Detection Based on Ultrasonic Sensors

PubMed Central

Li, Hanzhe; Zhai, Changyuan; Weckler, Paul; Wang, Ning; Yang, Shuo; Zhang, Bo

2016-01-01

Orchard target-oriented variable rate spraying is an effective method to reduce pesticide drift and excessive residues. To accomplish this task, the orchard targets’ characteristic information is needed to control liquid flow rate and airflow rate. One of the most important characteristics is the canopy density. In order to establish the canopy density model for a planar orchard target which is indispensable for canopy density calculation, a target density detection testing system was developed based on an ultrasonic sensor. A time-domain energy analysis method was employed to analyze the ultrasonic signal. Orthogonal regression central composite experiments were designed and conducted using man-made canopies of known density with three or four layers of leaves. Two model equations were obtained, of which the model for the canopies with four layers was found to be the most reliable. A verification test was conducted with different layers at the same density values and detecting distances. The test results showed that the relative errors of model density values and actual values of five, four, three and two layers of leaves were acceptable, while the maximum relative errors were 17.68%, 25.64%, 21.33% and 29.92%, respectively. It also suggested the model equation with four layers had a good applicability with different layers which increased with adjacent layers. PMID:28029132

Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices

DOE PAGES

Hubertus J. J. van Dam

2016-04-27

Density functional theory is currently the most widely applied method in electronic structure theory. The Kohn-Sham method, based on a fictitious system of noninteracting particles, is the workhorse of the theory. The particular form of the Kohn-Sham wave function admits only idempotent one-electron density matrices whereas wave functions of correlated electrons in post-Hartree-Fock methods invariably have fractional occupation numbers. Here we show that by generalizing the orbital concept and introducing a suitable dot product as well as a probability density, a noninteracting system can be chosen that can represent the one-electron density matrix of any system, even one with fractionalmore » occupation numbers. This fictitious system ensures that the exact electron density is accessible within density functional theory. It can also serve as the basis for reduced density matrix functional theory. Moreover, to aid the analysis of the results the orbitals may be assigned energies from a mean-field Hamiltonian. This produces energy levels that are akin to Hartree-Fock orbital energies such that conventional analyses based on Koopmans' theorem are available. Lastly, this system is convenient in formalisms that depend on creation and annihilation operators as they are trivially applied to single-determinant wave functions.« less

A Multivariate Genome-Wide Association Analysis of 10 LDL Subfractions, and Their Response to Statin Treatment, in 1868 Caucasians

PubMed Central

Shim, Heejung; Chasman, Daniel I.; Smith, Joshua D.; Mora, Samia; Ridker, Paul M.; Nickerson, Deborah A.; Krauss, Ronald M.; Stephens, Matthew

2015-01-01

We conducted a genome-wide association analysis of 7 subfractions of low density lipoproteins (LDLs) and 3 subfractions of intermediate density lipoproteins (IDLs) measured by gradient gel electrophoresis, and their response to statin treatment, in 1868 individuals of European ancestry from the Pharmacogenomics and Risk of Cardiovascular Disease study. Our analyses identified four previously-implicated loci (SORT1, APOE, LPA, and CETP) as containing variants that are very strongly associated with lipoprotein subfractions (log10Bayes Factor > 15). Subsequent conditional analyses suggest that three of these (APOE, LPA and CETP) likely harbor multiple independently associated SNPs. Further, while different variants typically showed different characteristic patterns of association with combinations of subfractions, the two SNPs in CETP show strikingly similar patterns - both in our original data and in a replication cohort - consistent with a common underlying molecular mechanism. Notably, the CETP variants are very strongly associated with LDL subfractions, despite showing no association with total LDLs in our study, illustrating the potential value of the more detailed phenotypic measurements. In contrast with these strong subfraction associations, genetic association analysis of subfraction response to statins showed much weaker signals (none exceeding log10Bayes Factor of 6). However, two SNPs (in APOE and LPA) previously-reported to be associated with LDL statin response do show some modest evidence for association in our data, and the subfraction response proles at the LPA SNP are consistent with the LPA association, with response likely being due primarily to resistance of Lp(a) particles to statin therapy. An additional important feature of our analysis is that, unlike most previous analyses of multiple related phenotypes, we analyzed the subfractions jointly, rather than one at a time. Comparisons of our multivariate analyses with standard univariate analyses demonstrate that multivariate analyses can substantially increase power to detect associations. Software implementing our multivariate analysis methods is available at http://stephenslab.uchicago.edu/software.html. PMID:25898129

Growth, characterization and estimation of lattice strain and size in CdS nanoparticles: X-ray peak profile analysis

NASA Astrophysics Data System (ADS)

Solanki, Rekha Garg; Rajaram, Poolla; Bajpai, P. K.

2018-05-01

This work is based on the growth, characterization and estimation of lattice strain and crystallite size in CdS nanoparticles by X-ray peak profile analysis. The CdS nanoparticles were synthesized by a non-aqueous solvothermal method and were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and UV-visible spectroscopy. XRD confirms that the CdS nanoparticles have the hexagonal structure. The Williamson-Hall (W-H) method was used to study the X-ray peak profile analysis. The strain-size plot (SSP) was used to study the individual contributions of crystallite size and lattice strain from the X-rays peaks. The physical parameters such as strain, stress and energy density values were calculated using various models namely, isotropic strain model, anisotropic strain model and uniform deformation energy density model. The particle size was estimated from the TEM images to be in the range of 20-40 nm. The Raman spectrum shows the characteristic optical 1LO and 2LO vibrational modes of CdS. UV-visible absorption studies show that the band gap of the CdS nanoparticles is 2.48 eV. The results show that the crystallite size estimated from Scherrer's formula, W-H plots, SSP and the particle size calculated by TEM images are approximately similar.

Spatial pattern evolution of Aedes aegypti breeding sites in an Argentinean city without a dengue vector control programme.

PubMed

Espinosa, Manuel O; Polop, Francisco; Rotela, Camilo H; Abril, Marcelo; Scavuzzo, Carlos M

2016-11-21

The main objective of this study was to obtain and analyse the space-time dynamics of Aedes aegypti breeding sites in Clorinda City, Formosa Province, Argentina coupled with landscape analysis using the maximum entropy approach in order to generate a dengue vector niche model. In urban areas, without vector control activities, 12 entomologic (larval) samplings were performed during three years (October 2011 to October 2014). The entomologic surveillance area represented 16,511 houses. Predictive models for Aedes distribution were developed using vector breeding abundance data, density analysis, clustering and geoprocessing techniques coupled with Earth observation satellite data. The spatial analysis showed a vector spatial distribution pattern with clusters of high density in the central region of Clorinda with a well-defined high-risk area in the western part of the city. It also showed a differential temporal behaviour among different areas, which could have implications for risk models and control strategies at the urban scale. The niche model obtained for Ae. aegypti, based on only one year of field data, showed that 85.8% of the distribution of breeding sites is explained by the percentage of water supply (48.2%), urban distribution (33.2%), and the percentage of urban coverage (4.4%). The consequences for the development of control strategies are discussed with reference to the results obtained using distribution maps based on environmental variables.

Data Fitting to Study Ablated Hard Dental Tissues by Nanosecond Laser Irradiation.

PubMed

Al-Hadeethi, Y; Al-Jedani, S; Razvi, M A N; Saeed, A; Abdel-Daiem, A M; Ansari, M Shahnawaze; Babkair, Saeed S; Salah, Numan A; Al-Mujtaba, A

2016-01-01

Laser ablation of dental hard tissues is one of the most important laser applications in dentistry. Many works have reported the interaction of laser radiations with tooth material to optimize laser parameters such as wavelength, energy density, etc. This work has focused on determining the relationship between energy density and ablation thresholds using pulsed, 5 nanosecond, neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12 (Nd:YAG) laser at 1064 nanometer. For enamel and dentin tissues, the ablations have been performed using laser-induced breakdown spectroscopy (LIBS) technique. The ablation thresholds and relationship between energy densities and peak areas of calcium lines, which appeared in LIBS, were determined using data fitting. Furthermore, the morphological changes were studied using Scanning Electron Microscope (SEM). Moreover, the chemical stability of the tooth material after ablation has been studied using Energy-Dispersive X-Ray Spectroscopy (EDX). The differences between carbon atomic % of non-irradiated and irradiated samples were tested using statistical t-test. Results revealed that the best fitting between energy densities and peak areas of calcium lines were exponential and linear for enamel and dentin, respectively. In addition, the ablation threshold of Nd:YAG lasers in enamel was higher than that of dentin. The morphology of the surrounded ablated region of enamel showed thermal damages. For enamel, the EDX quantitative analysis showed that the atomic % of carbon increased significantly when laser energy density increased.

Evidence of codon usage in the nearest neighbor spacing distribution of bases in bacterial genomes

NASA Astrophysics Data System (ADS)

Higareda, M. F.; Geiger, O.; Mendoza, L.; Méndez-Sánchez, R. A.

2012-02-01

Statistical analysis of whole genomic sequences usually assumes a homogeneous nucleotide density throughout the genome, an assumption that has been proved incorrect for several organisms since the nucleotide density is only locally homogeneous. To avoid giving a single numerical value to this variable property, we propose the use of spectral statistics, which characterizes the density of nucleotides as a function of its position in the genome. We show that the cumulative density of bases in bacterial genomes can be separated into an average (or secular) plus a fluctuating part. Bacterial genomes can be divided into two groups according to the qualitative description of their secular part: linear and piecewise linear. These two groups of genomes show different properties when their nucleotide spacing distribution is studied. In order to analyze genomes having a variable nucleotide density, statistically, the use of unfolding is necessary, i.e., to get a separation between the secular part and the fluctuations. The unfolding allows an adequate comparison with the statistical properties of other genomes. With this methodology, four genomes were analyzed Burkholderia, Bacillus, Clostridium and Corynebacterium. Interestingly, the nearest neighbor spacing distributions or detrended distance distributions are very similar for species within the same genus but they are very different for species from different genera. This difference can be attributed to the difference in the codon usage.

Spherical Al-substituted ɑ-nickel hydroxide with high tapping density applied in Ni-MH battery

NASA Astrophysics Data System (ADS)

Wu, Xing-Hua; Feng, Qing-Ping; Wang, Man; Huang, Gui-Wen

2016-10-01

Spherical Al-substituted ɑ-Ni(OH)2 with high tapping density are prepared with controlled crystallization method, where the synthesis parameters are previously calculated out according to theoretical analysis. The formation mechanism of Ni(OH)2 particles is analyzed based on theoretical calculation, the optimal conditions for the formation of spherical Al-substituted ɑ-Ni(OH)2 with high tapping density are figured out and a formula indicates the restrictions among main synthesis parameters is derived, which is reference meaningful for the synthesis of commercialized electrode powders. Synthesized by using the calculated parameters, the obtained ɑ-Ni(OH)2 shows uniform spherical morphology, high crystal phase purity and reasonable high tapping density of 1.37 g cm-3, which demonstrates the feasibility of the derived formula. Since the electrical conductivity of the pure Ni(OH)2 is quite low, 5 wt% of CoOOH are coated on the ɑ-Ni(OH)2 surface to improve their electrochemical performances. The synthesized CoOOH coated ɑ-Ni(OH)2 shows relative high specific capacity of 327 mAh g-1 at 0.1 C and acceptable high-rate dischargeability. The simultaneously achieving of high tapping density and high specific capacity in ɑ-Ni(OH)2 makes it own the great potential to be applied in new generation of Ni-MH batteries.

Large-scale magmatic layering in the Main Zone of the Bushveld Complex and episodic downward magma infiltration

NASA Astrophysics Data System (ADS)

Hayes, Ben; Ashwal, Lewis D.; Webb, Susan J.; Bybee, Grant M.

2017-03-01

The Bellevue drillcore intersects 3 km of Main and Upper Zone cumulates in the Northern Limb of the Bushveld Complex. Main Zone cumulates are predominately gabbronorites, with localized layers of pyroxenite and anorthosite. Some previous workers, using bulk rock major, trace and isotopic compositions, have suggested that the Main Zone crystallized predominantly from a single pulse of magma. However, density measurements throughout the Bellevue drillcore reveal intervals that show up-section increases in bulk rock density, which are difficult to explain by crystallization from a single batch of magma. Wavelet analysis of the density data suggests that these intervals occur on length-scales of 40 to 170 m, thus defining a scale of layering not previously described in the Bushveld Complex. Upward increases in density in the Main Zone correspond to upward increases in modal pyroxene, producing intervals that grade from a basal anorthosite (with 5% pyroxene) to gabbronorite (with 30-40% pyroxene). We examined the textures and mineral compositions of a 40 m thick interval showing upwardly increasing density to establish how this type of layering formed. Plagioclase generally forms euhedral laths, while orthopyroxene is interstitial in texture and commonly envelops finer-grained and embayed plagioclase grains. Minor interstitial clinopyroxene was the final phase to crystallize from the magma. Plagioclase compositions show negligible change up-section (average An62), with local reverse zoning at the rims of cumulus laths (average increase of 2 mol%). In contrast, interstitial orthopyroxene compositions become more primitive up-section, from Mg# 57 to Mg# 63. Clinopyroxene similarly shows an up-section increase in Mg#. Pyroxene compositions record the primary magmatic signature of the melt at the time of crystallization and are not an artefact of the trapped liquid shift effect. Combined, the textures and decoupled mineral compositions indicate that the upward density increase is produced by the downward infiltration of noritic magma into a previously emplaced plagioclase-rich crystal mush. Fresh noritic magma soaked down into the crystallizing anorthositic mush, partially dissolving plagioclase laths and assimilating Fe-enriched pore melt. The presence of multiple cycles showing upward increases in density in the Bellevue drillcore suggests that downward magma infiltration occurred episodically during crystallization of the Main Zone.

Quantum mechanical study of the structure and spectroscopic (FT-IR, FT-Raman, 13C, 1H and UV), first order hyperpolarizabilities, NBO and TD-DFT analysis of the 4-methyl-2-cyanobiphenyl

NASA Astrophysics Data System (ADS)

Sebastian, S.; Sundaraganesan, N.; Karthikeiyan, B.; Srinivasan, V.

2011-02-01

The Fourier transform infrared (FT-IR) and FT-Raman of 4-methyl-2-cyanobiphenyl (4M2CBP) have been recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been investigated with the help of density functional theory (DFT) method. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge including atomic orbital (GIAO) method. The first order hyperpolarizability ( β0) of this novel molecular system and related properties ( β, α0 and Δ α) of 4M2CBP are calculated using HF/6-311G(d,p) method on the finite-field approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* and π* antibonding orbitals and second order delocalization energies ( E2) confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. UV-vis spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) approach. Finally the calculations results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra.

Noise in restaurants: levels and mathematical model.

PubMed

To, Wai Ming; Chung, Andy

2014-01-01

Noise affects the dining atmosphere and is an occupational hazard to restaurant service employees worldwide. This paper examines the levels of noise in dining areas during peak hours in different types of restaurants in Hong Kong SAR, China. A mathematical model that describes the noise level in a restaurant is presented. The 1-h equivalent continuous noise level (L(eq,1-h)) was measured using a Type-1 precision integral sound level meter while the occupancy density, the floor area of the dining area, and the ceiling height of each of the surveyed restaurants were recorded. It was found that the measured noise levels using Leq,1-h ranged from 67.6 to 79.3 dBA in Chinese restaurants, from 69.1 to 79.1 dBA in fast food restaurants, and from 66.7 to 82.6 dBA in Western restaurants. Results of the analysis of variance show that there were no significant differences between means of the measured noise levels among different types of restaurants. A stepwise multiple regression analysis was employed to determine the relationships between geometrical and operational parameters and the measured noise levels. Results of the regression analysis show that the measured noise levels depended on the levels of occupancy density only. By reconciling the measured noise levels and the mathematical model, it was found that people in restaurants increased their voice levels when the occupancy density increased. Nevertheless, the maximum measured hourly noise level indicated that the noise exposure experienced by restaurant service employees was below the regulated daily noise exposure value level of 85 dBA.

Analysis of Energy Consumption for Ad Hoc Wireless Sensor Networks Using a Bit-Meter-per-Joule Metric

NASA Astrophysics Data System (ADS)

Gao, J. L.

2002-04-01

In this article, we present a system-level characterization of the energy consumption for sensor network application scenarios. We compute a power efficiency metric -- average watt-per-meter -- for each radio transmission and extend this local metric to find the global energy consumption. This analysis shows how overall energy consumption varies with transceiver characteristics, node density, data traffic distribution, and base-station location.

Traditional cattle vs. introduced deer management in Chaco Serrano woodlands (Argentina): Analysis of environmental sustainability at increasing densities.

PubMed

Charro, José Luis; López-Sánchez, Aida; Perea, Ramón

2018-01-15

Wild ungulate populations have increased and expanded considerably in many regions, including austral woodlands and forests where deer (Cervus elaphus) have been introduced as an alternative management to traditional cattle grazing. In this study, we compared traditional cattle with introduced deer management at increasing deer densities in the "Chaco Serrano" woodlands of Argentina to assess their ecological sustainability. We used three ecological indicators (abundance of tree regeneration, woody plant diversity and browsing damage) as proxies for environmental sustainability in woody systems. Our results indicate that traditional cattle management, at stocking rates of ∼10 ind km -2 , was the most ecologically sustainable management since it allowed greater tree regeneration abundance, higher richness of woody species and lower browsing damage. Importantly, cattle management and deer management at low densities (10 ind km -2 ) showed no significant differences in species richness and abundance of seedlings, although deer caused greater browsing damage on saplings and juveniles. However, management regimes involving high deer densities (∼35 deer km 2 ) was highly unsustainable in comparison to low (∼10 deer km -2 ) and medium (∼20 deer km -2 ) densities, with 40% probability of unsustainable browsing as opposed to less than 5% probability at low and medium densities. In addition, high deer densities caused a strong reduction in tree regeneration, with a 19-30% reduction in the abundance of seedlings and young trees when compared to low deer densities. These results showed that the effect of increasing deer densities on woody plant conservation was not linear, with high deer densities causing a disproportional deleterious effect on tree regeneration and sustainable browsing. Our results suggest that traditional management at low densities or the use of introduced ungulates (deer breeding areas) at low-medium densities (<20 deer km -2 ) are compatible with woody vegetation conservation. However, further research is needed on plant palatability, animal habitat use (spatial heterogeneity) and species turnover and extinction (comparison to areas of low-null historical browsing) to better estimate environmental sustainability of Neotropical ungulate-dominated woodlands. Copyright © 2017 Elsevier Ltd. All rights reserved.

Neutron densities from a global analysis of medium-energy proton-nucleus elastic scattering

NASA Astrophysics Data System (ADS)

Clark, B. C.; Kerr, L. J.; Hama, S.

2003-05-01

A new method for extracting neutron densities from intermediate-energy elastic proton-nucleus scattering observables uses a global Dirac phenomenological approach based on the relativistic impulse approximation. Datasets for 40Ca, 48Ca, and 208Pb in the energy range from 500 MeV to 1040 MeV are considered. The global fits are successful in reproducing the data and in predicting datasets not included in the analysis. Using this global approach, energy-independent neutron densities are obtained. The vector point proton density distribution ρpv is determined from the empirical charge density after unfolding the proton form factor. The other densities, ρnv, ρps, ρns, are parametrized. This work provides energy-independent values for the rms neutron radius Rn and the neutron skin thickness Sn, in contrast to the energy-dependent values obtained by previous studies. In addition, the results presented in this paper show that the expected rms neutron radius and the skin thickness for 40Ca are accurately reproduced. The values of Rn and Sn obtained from the global fits that we consider to be the most reliable are given as follows: for 40Ca, 3.314>Rn>3.310 fm and -0.063>Sn >-0.067 fm; for 48Ca, 3.459>Rn>3.413 fm and 0.102>Sn>0.056 fm; and for 208Pb, 5.550>Rn>5.522 fm and 0.111>Sn>0.083 fm. These values are in reasonable agreement with nonrelativistic Skyrme-Hartree-Fock models and with relativistic Hartree-Bogoliubov models with density-dependent meson-nucleon couplings. The results from the global fits for 48Ca and 208Pb are generally not in agreement with the usual relativistic mean-field models.

Bubbling in unbounded coflowing liquids.

PubMed

Gañán-Calvo, Alfonso M; Herrada, Miguel A; Garstecki, Piotr

2006-03-31

An investigation of the stability of low density and viscosity fluid jets and spouts in unbounded coflowing liquids is presented. A full parametrical analysis from low to high Weber and Reynolds numbers shows that the presence of any fluid of finite density and viscosity inside the hollow jet elicits a transition from an absolute to a convective instability at a finite value of the Weber number, for any value of the Reynolds number. Below that critical value of the Weber number, the absolute character of the instability leads to local breakup, and consequently to local bubbling. Experimental data support our model.

Comprehensive numerical methodology for direct numerical simulations of compressible Rayleigh-Taylor instability

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

Reckinger, Scott James; Livescu, Daniel; Vasilyev, Oleg V.

A comprehensive numerical methodology has been developed that handles the challenges introduced by considering the compressive nature of Rayleigh-Taylor instability (RTI) systems, which include sharp interfacial density gradients on strongly stratified background states, acoustic wave generation and removal at computational boundaries, and stratification-dependent vorticity production. The computational framework is used to simulate two-dimensional single-mode RTI to extreme late-times for a wide range of flow compressibility and variable density effects. The results show that flow compressibility acts to reduce the growth of RTI for low Atwood numbers, as predicted from linear stability analysis.

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

Zúñiga-Segundo, Arturo; Juárez-Amaro, Raúl; Aguilar-Loreto, Omar

We study the atom–field interaction when the field is in a mixture of coherent states. We show that in this case it is possible to calculate analytically the field entropy for times of the order of twice the collapse time. Such analytical results are done with the help of numerical analysis. We also give an expression in terms of Chebyshev polynomials for power of density matrices. - Highlights: • We calculate the field entropy for times of the order of twice the collapse time. • We give a relation between powers of the density matrices of the subsystems. • Entropymore » operators for both subsystems are obtained.« less

Pesticide occurrence in groundwater in areas of high-density row crop production in Alabama, 2009

USGS Publications Warehouse

Moreland, Richard S.

2011-01-01

High-density row crop production occurs in three areas of Alabama that are underlain by productive aquifers, northern Alabama, southeastern Alabama, and Baldwin County in southwestern Alabama. The U.S. Geological Survey collected five groundwater samples from each of these three areas during 2009 for analysis of selected pesticides. Results of these analyses showed detections for 37 of 152 analytes. The three most frequently detected compounds were atrazine, 2-Chloro-4-isopropylamino-6-amino-triazine (CIAT), and metolachlor. The highest concentration for any analyte was 4.08 micrograms per liter for metolachlor.

High data density temperature measurement for quasi steady-state flows

NASA Technical Reports Server (NTRS)

Mercer, Carolyn R.; Rashidnia, Nasser; Creath, Katherine

1995-01-01

A new optical instrument, the liquid crystal point diffraction interferometer (LCPDI), is used to measure the temperature distribution across a heated chamber filled with silicone oil. Data taken using the LCPDI are compared to equivalent measurements made with a traversing thermocouple and the two data sets show excellent agreement This instrument maintains the compact, robust design of Linnik's point diffraction interferometer and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with very high data density and with automated data reduction.

High Data Density Temperature Measurement for Quasi Steady-State Flows

NASA Technical Reports Server (NTRS)

Mercer, C. R.; Rashidnia, N.; Creath, K.

1996-01-01

A new optical instrument, the liquid crystal point diffraction interferometer (LCPDI), is used to measure the temperature distribution across a heated chamber filled with silicone oil. Data taken using the LCPDI are compared to equivalent measurements made with a traversing thermo-couple and the two data sets show excellent agreement. This instrument maintains the compact, robust design of Linniks point diffraction interferometer and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wave-fronts with very high data density and with automated data reduction.

Comparative Study of Human and Mouse Postsynaptic Proteomes Finds High Compositional Conservation and Abundance Differences for Key Synaptic Proteins

PubMed Central

Bayés, Àlex; Collins, Mark O.; Croning, Mike D. R.; van de Lagemaat, Louie N.; Choudhary, Jyoti S.; Grant, Seth G. N.

2012-01-01

Direct comparison of protein components from human and mouse excitatory synapses is important for determining the suitability of mice as models of human brain disease and to understand the evolution of the mammalian brain. The postsynaptic density is a highly complex set of proteins organized into molecular networks that play a central role in behavior and disease. We report the first direct comparison of the proteome of triplicate isolates of mouse and human cortical postsynaptic densities. The mouse postsynaptic density comprised 1556 proteins and the human one 1461. A large compositional overlap was observed; more than 70% of human postsynaptic density proteins were also observed in the mouse postsynaptic density. Quantitative analysis of postsynaptic density components in both species indicates a broadly similar profile of abundance but also shows that there is higher abundance variation between species than within species. Well known components of this synaptic structure are generally more abundant in the mouse postsynaptic density. Significant inter-species abundance differences exist in some families of key postsynaptic density proteins including glutamatergic neurotransmitter receptors and adaptor proteins. Furthermore, we have identified a closely interacting set of molecules enriched in the human postsynaptic density that could be involved in dendrite and spine structural plasticity. Understanding synapse proteome diversity within and between species will be important to further our understanding of brain complexity and disease. PMID:23071613

Characterization of bone collagen organization defects in murine hypophosphatasia using a Zernike model of optical aberrations

NASA Astrophysics Data System (ADS)

Tehrani, Kayvan Forouhesh; Pendleton, Emily G.; Leitmann, Bobby; Barrow, Ruth; Mortensen, Luke J.

2018-02-01

Bone growth and strength is severely impacted by Hypophosphatasia (HPP). It is a genetic disease that affects the mineralization of the bone. We hypothesize that it impacts overall organization, density, and porosity of collagen fibers. Lower density of fibers and higher porosity cause less absorption and scattering of light, and therefore a different regime of transport mean free path. To find a cure for this disease, a metric for the evaluation of bone is required. Here we present an evaluation method based on our Phase Accumulation Ray Tracing (PART) method. This method uses second harmonic generation (SHG) in bone collagen fiber to model bone indices of refraction, which is used to calculate phase retardation on the propagation path of light in bone. The calculated phase is then expanded using Zernike polynomials up to 15th order, to make a quantitative analysis of tissue anomalies. Because the Zernike modes are a complete set of orthogonal polynomials, we can compare low and high order modes in HPP, compare them with healthy wild type mice, to identify the differences between their geometry and structure. Larger coefficients of low order modes show more uniform fiber density and less porosity, whereas the opposite is shown with larger coefficients of higher order modes. Our analyses show significant difference between Zernike modes in different types of bone evidenced by Principal Components Analysis (PCA).

Density functional theory calculations on transition metal atoms adsorbed on graphene monolayers

NASA Astrophysics Data System (ADS)

Dimakis, Nicholas; Flor, Fernando Antonio; Salgado, Andres; Adjibi, Kolade; Vargas, Sarah; Saenz, Justin

2017-11-01

Transition metal atom adsorption on graphene monolayers has been elucidated using periodic density functional theory under hybrid and generalized gradient approximation functionals. More specifically, we examined the adsorption of Cu, Fe, Zn, Ru, and Os on graphene monolayers by calculating, among others, the electronic density-of-states spectra of the adatom-graphene system and the overlap populations of the adatom with the nearest adsorbing graphene carbon atoms. These calculations reveal that Cu form primarily covalent bonds with graphene atoms via strong hybridization between the adatom orbitals and the sp band of the graphene substrate, whereas the interaction of the Ru and Os with graphene also contain ionic parts. Although the interaction of Fe with graphene atoms is mostly covalent, some charge transfer to graphene is also observed. The interaction of Zn with graphene is weak. Mulliken population analysis and charge contour maps are used to elucidate charge transfers between the adatom and the substrate. The adsorption strength is correlated with the metal adsorption energy and the height of the metal adatom from the graphene plane for the geometrically optimized adatom-graphene system. Our analysis shows that show that metal adsorption strength follows the adatom trend Ru ≈ Os > Fe > Cu > Zn, as verified by corresponding changes in the adsorption energies. The increased metal-carbon orbital overlap for the Ru relative to Os adatom is attributed to hybridization defects.

The added value of ordinal analysis in clinical trials: an example in traumatic brain injury.

PubMed

Roozenbeek, Bob; Lingsma, Hester F; Perel, Pablo; Edwards, Phil; Roberts, Ian; Murray, Gordon D; Maas, Andrew Ir; Steyerberg, Ewout W

2011-01-01

In clinical trials, ordinal outcome measures are often dichotomized into two categories. In traumatic brain injury (TBI) the 5-point Glasgow outcome scale (GOS) is collapsed into unfavourable versus favourable outcome. Simulation studies have shown that exploiting the ordinal nature of the GOS increases chances of detecting treatment effects. The objective of this study is to quantify the benefits of ordinal analysis in the real-life situation of a large TBI trial. We used data from the CRASH trial that investigated the efficacy of corticosteroids in TBI patients (n = 9,554). We applied two techniques for ordinal analysis: proportional odds analysis and the sliding dichotomy approach, where the GOS is dichotomized at different cut-offs according to baseline prognostic risk. These approaches were compared to dichotomous analysis. The information density in each analysis was indicated by a Wald statistic. All analyses were adjusted for baseline characteristics. Dichotomous analysis of the six-month GOS showed a non-significant treatment effect (OR = 1.09, 95% CI 0.98 to 1.21, P = 0.096). Ordinal analysis with proportional odds regression or sliding dichotomy showed highly statistically significant treatment effects (OR 1.15, 95% CI 1.06 to 1.25, P = 0.0007 and 1.19, 95% CI 1.08 to 1.30, P = 0.0002), with 2.05-fold and 2.56-fold higher information density compared to the dichotomous approach respectively. Analysis of the CRASH trial data confirmed that ordinal analysis of outcome substantially increases statistical power. We expect these results to hold for other fields of critical care medicine that use ordinal outcome measures and recommend that future trials adopt ordinal analyses. This will permit detection of smaller treatment effects.

Inward transport of a toroidally confined plasma subject to strong radial electric fields

NASA Technical Reports Server (NTRS)

Roth, J. R.; Krawczonek, W. M.; Powers, E. J.; Hong, J.; Kim, Y.

1977-01-01

The paper aims at showing that the density and confinement time of a toroidal plasma can be enhanced by radial electric fields far stronger than the ambipolar values, and that, if such electric fields point into the plasma, radially inward transport can result. The investigation deals with low-frequency fluctuation-induced transport using digitally implemented spectral analysis techniques and with the role of strong applied radial electric fields and weak vertical magnetic fields on plasma density and particle confinement times in a Bumpy Torus geometry. Results indicate that application of sufficiently strong radially inward electric fields results in radially inward fluctuation-induced transport into the toroidal electrostatic potential well; this inward transport gives rise to higher average electron densities and longer particle confinement times in the toroidal plasma.

Detecting illegal intra-corporeal cocaine containers: Which factors influence their density?

PubMed

Platon, Alexandra; Herrera, Bruno; Becker, Minerva; Perneger, Thomas; Getaz, Laurent; Wolff, Hans; Lock, Eric; Rutschmann, Olivier; Poletti, Pierre-Alexandre

2018-05-30

To determine parameters related to hyperdensity (>40 HU) of intra-corporeal cocaine packets on low-dose CT (LDCT); hyperdensity increases detectability on abdominal radiographs. LDCT showing drug packets (n = 46) were analyzed for mean radiological density and packets volume. Following expulsion, packets weight and cocaine concentration were measured. Hypercompaction was defined as >0.9 g/cm 3 . Packets were hyperdense in 33 cases (72%). Mean compaction was 1.0 g/cm 3 , mean density 118.5 HU and mean cocaine concentration 44.2%. On multivariate analysis, only high compaction remained significantly related to hyperdensity (p = 0.001). Compaction >0.9 g/cm 3 is the only parameter significantly associated with hyperdense packets. Copyright © 2018 Elsevier Inc. All rights reserved.

Absorption of the laser radiation by the laser plasma with gas microjet targets

NASA Astrophysics Data System (ADS)

Borisevichus, D. A.; Zabrodskii, V. V.; Kalmykov, S. G.; Sasin, M. E.; Seisyan, R. P.

2017-01-01

An upper limit of absorption of the laser radiation in the plasma produced in a gas jet Xe target with the average density of (3-6) × 1018 cm-3 and the effective diameter of 0.7 mm is found. It is equal to ≈50% and remains constant under any variation in this range of densities. This result contradicts both theoretical assessments that have predicted virtually complete absorption and results of earlier experiments with the laser spark in an unlimited stationary Xe gas with the same density, where the upper limit of absorption was close to 100%. An analysis shows that nonlinearity of absorption and plasma nonequilibrium lead to the reduction of the absorption coefficient that, along with the limited size of plasma, can explain the experimental results.

Measurement of the perfusion fraction in brain tumors with intravoxel incoherent motion MR imaging: validation with histopathological vascular density in meningiomas.

PubMed

Togao, Osamu; Hiwatashi, Akio; Yamashita, Koji; Kikuchi, Kazufumi; Momosaka, Daichi; Yoshimoto, Koji; Kuga, Daisuke; Mizoguchi, Masahiro; Suzuki, Satoshi O; Iwaki, Toru; Van Cauteren, Marc; Iihara, Koji; Honda, Hiroshi

2018-05-01

To evaluate the quantification performance of the perfusion fraction (f) measured with intravoxel incoherent motion (IVIM) MR imaging in a comparison with the histological vascular density in meningiomas. 29 consecutive patients with meningioma (59.0 ± 16.8 years old, 8 males and 21 females) who underwent a subsequent surgical resection were examined with both IVIM imaging and a histopathological analysis. IVIM imaging was conducted using a single-shot SE-EPI sequence with 13 b-factors (0, 10, 20, 30, 50, 80, 100, 200, 300, 400, 600, 800, 1000 s mm - 2 ) at 3T. The perfusion fraction (f) was calculated by fitting the IVIM bi-exponential model. The 90-percentile f-value in the tumor region-of-interest (ROI) was defined as the maximum f-value (f-max). Histopathological vascular density (%Vessel) was measured on CD31-immunostainted histopathological specimens. The correlation and agreement between the f-values and %Vessel was assessed. The f-max (15.5 ± 5.5%) showed excellent agreement [intraclass correlation coefficient (ICC) = 0.754] and a significant correlation (r = 0.69, p < 0.0001) with the %Vessel (12.9 ± 9.4%) of the tumors. The Bland-Altman plot analysis showed excellent agreement between the f-max and %Vessel (bias, -2.6%; 95% limits of agreement, from -16.0 to 10.8%). The f-max was not significantly different among the histological subtypes of meningioma. An excellent agreement and a significant correlation were observed between the f-values and %Vessel. The f-value can be used as a noninvasive quantitative imaging measure to directly assess the vascular volume fraction in brain tumors. Advances in knowledge: The f-value measured by IVIM imaging showed a significant correlation and an excellent agreement with the histological vascular density in the meningiomas. The f-value can be used as a noninvasive and quantitative imaging measure to directly assess the volume fraction of capillaries in brain tumors.

Analysis of parenchymal patterns using conspicuous spatial frequency features in mammograms applied to the BI-RADS density rating scheme

NASA Astrophysics Data System (ADS)

Perconti, Philip; Loew, Murray

2006-03-01

Automatic classification of the density of breast parenchyma is shown using a measure that is correlated to the human observer performance, and compared against the BI-RADS density rating. Increasingly popular in the United States, the Breast Imaging Reporting and Data System (BI-RADS) is used to draw attention to the increased screening difficulty associated with greater breast density; however, the BI-RADS rating scheme is subjective and is not intended as an objective measure of breast density. So, while popular, BI-RADS does not define density classes using a standardized measure, which leads to increased variability among observers. The adaptive thresholding technique is a more quantitative approach for assessing the percentage breast density, but considerable reader interaction is required. We calculate an objective density rating that is derived using a measure of local feature salience. Previously, this measure was shown to correlate well with radiologists' localization and discrimination of true positive and true negative regions-of-interest. Using conspicuous spatial frequency features, an objective density rating is obtained and correlated with adaptive thresholding, and the subjectively ascertained BI-RADS density ratings. Using 100 cases, obtained from the University of South Florida's DDSM database, we show that an automated breast density measure can be derived that is correlated with the interactive thresholding method for continuous percentage breast density, but not with the BI-RADS density rating categories for the selected cases. Comparison between interactive thresholding and the new salience percentage density resulted in a Pearson correlation of 76.7%. Using a four-category scale equivalent to the BI-RADS density categories, a Spearman correlation coefficient of 79.8% was found.

Unusually short chalcogen bonds involving organoselenium: insights into the Se-N bond cleavage mechanism of the antioxidant ebselen and analogues.

PubMed

Thomas, Sajesh P; Satheeshkumar, K; Mugesh, Govindasamy; Guru Row, T N

2015-04-27

Structural studies on the polymorphs of the organoselenium antioxidant ebselen and its derivative show the potential of organic selenium to form unusually short Se⋅⋅⋅O chalcogen bonds that lead to conserved supramolecular recognition units. Se⋅⋅⋅O interactions observed in these polymorphs are the shortest such chalcogen bonds known for organoselenium compounds. The FTIR spectral evolution characteristics of this interaction from solution state to solid crystalline state further validates the robustness of this class of supramolecular recognition units. The strength and electronic nature of the Se⋅⋅⋅O chalcogen bonds were explored using high-resolution X-ray charge density analysis and atons-in-molecules (AIM) theoretical analysis. A charge density study unravels the strong electrostatic nature of Se⋅⋅⋅O chalcogen bonding and soft-metal-like behavior of organoselenium. An analysis of the charge density around Se-N and Se-C covalent bonds in conjunction with the Se⋅⋅⋅O chalcogen bonding modes in ebselen and its analogues provides insights into the mechanism of drug action in this class of organoselenium antioxidants. The potential role of the intermolecular Se⋅⋅⋅O chalcogen bonding in forming the intermediate supramolecular assembly that leads to the bond cleavage mechanism has been proposed in terms of electron density topological parameters in a series of molecular complexes of ebselen with reactive oxygen species (ROS). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Estimating the spatial distribution of soil organic matter density and geochemical properties in a polygonal shaped Arctic Tundra using core sample analysis and X-ray computed tomography

NASA Astrophysics Data System (ADS)

Soom, F.; Ulrich, C.; Dafflon, B.; Wu, Y.; Kneafsey, T. J.; López, R. D.; Peterson, J.; Hubbard, S. S.

2016-12-01

The Arctic tundra with its permafrost dominated soils is one of the regions most affected by global climate change, and in turn, can also influence the changing climate through biogeochemical processes, including greenhouse gas release or storage. Characterization of shallow permafrost distribution and characteristics are required for predicting ecosystem feedbacks to a changing climate over decadal to century timescales, because they can drive active layer deepening and land surface deformation, which in turn can significantly affect hydrological and biogeochemical responses, including greenhouse gas dynamics. In this study, part of the Next-Generation Ecosystem Experiment (NGEE-Arctic), we use X-ray computed tomography (CT) to estimate wet bulk density of cores extracted from a field site near Barrow AK, which extend 2-3m through the active layer into the permafrost. We use multi-dimensional relationships inferred from destructive core sample analysis to infer organic matter density, dry bulk density and ice content, along with some geochemical properties from nondestructive CT-scans along the entire length of the cores, which was not obtained by the spatially limited destructive laboratory analysis. Multi-parameter cross-correlations showed good agreement between soil properties estimated from CT scans versus properties obtained through destructive sampling. Soil properties estimated from cores located in different types of polygons provide valuable information about the vertical distribution of soil and permafrost properties as a function of geomorphology.

Stochastic population dynamics of a montane ground-dwelling squirrel.

PubMed

Hostetler, Jeffrey A; Kneip, Eva; Van Vuren, Dirk H; Oli, Madan K

2012-01-01

Understanding the causes and consequences of population fluctuations is a central goal of ecology. We used demographic data from a long-term (1990-2008) study and matrix population models to investigate factors and processes influencing the dynamics and persistence of a golden-mantled ground squirrel (Callospermophilus lateralis) population, inhabiting a dynamic subalpine habitat in Colorado, USA. The overall deterministic population growth rate λ was 0.94±SE 0.05 but it varied widely over time, ranging from 0.45±0.09 in 2006 to 1.50±0.12 in 2003, and was below replacement (λ<1) for 9 out of 18 years. The stochastic population growth rate λ(s) was 0.92, suggesting a declining population; however, the 95% CI on λ(s) included 1.0 (0.52-1.60). Stochastic elasticity analysis showed that survival of adult females, followed by survival of juvenile females and litter size, were potentially the most influential vital rates; analysis of life table response experiments revealed that the same three life history variables made the largest contributions to year-to year changes in λ. Population viability analysis revealed that, when the influences of density dependence and immigration were not considered, the population had a high (close to 1.0 in 50 years) probability of extinction. However, probability of extinction declined to as low as zero when density dependence and immigration were considered. Destabilizing effects of stochastic forces were counteracted by regulating effects of density dependence and rescue effects of immigration, which allowed our study population to bounce back from low densities and prevented extinction. These results suggest that dynamics and persistence of our study population are determined synergistically by density-dependence, stochastic forces, and immigration.

Stochastic Population Dynamics of a Montane Ground-Dwelling Squirrel

PubMed Central

Hostetler, Jeffrey A.; Kneip, Eva; Van Vuren, Dirk H.; Oli, Madan K.

2012-01-01

Understanding the causes and consequences of population fluctuations is a central goal of ecology. We used demographic data from a long-term (1990–2008) study and matrix population models to investigate factors and processes influencing the dynamics and persistence of a golden-mantled ground squirrel (Callospermophilus lateralis) population, inhabiting a dynamic subalpine habitat in Colorado, USA. The overall deterministic population growth rate λ was 0.94±SE 0.05 but it varied widely over time, ranging from 0.45±0.09 in 2006 to 1.50±0.12 in 2003, and was below replacement (λ<1) for 9 out of 18 years. The stochastic population growth rate λs was 0.92, suggesting a declining population; however, the 95% CI on λs included 1.0 (0.52–1.60). Stochastic elasticity analysis showed that survival of adult females, followed by survival of juvenile females and litter size, were potentially the most influential vital rates; analysis of life table response experiments revealed that the same three life history variables made the largest contributions to year-to year changes in λ. Population viability analysis revealed that, when the influences of density dependence and immigration were not considered, the population had a high (close to 1.0 in 50 years) probability of extinction. However, probability of extinction declined to as low as zero when density dependence and immigration were considered. Destabilizing effects of stochastic forces were counteracted by regulating effects of density dependence and rescue effects of immigration, which allowed our study population to bounce back from low densities and prevented extinction. These results suggest that dynamics and persistence of our study population are determined synergistically by density-dependence, stochastic forces, and immigration. PMID:22479616

Spectral density mapping at multiple magnetic fields suitable for 13C NMR relaxation studies

NASA Astrophysics Data System (ADS)

Kadeřávek, Pavel; Zapletal, Vojtěch; Fiala, Radovan; Srb, Pavel; Padrta, Petr; Přecechtělová, Jana Pavlíková; Šoltésová, Mária; Kowalewski, Jozef; Widmalm, Göran; Chmelík, Josef; Sklenář, Vladimír; Žídek, Lukáš

2016-05-01

Standard spectral density mapping protocols, well suited for the analysis of 15N relaxation rates, introduce significant systematic errors when applied to 13C relaxation data, especially if the dynamics is dominated by motions with short correlation times (small molecules, dynamic residues of macromolecules). A possibility to improve the accuracy by employing cross-correlated relaxation rates and on measurements taken at several magnetic fields has been examined. A suite of protocols for analyzing such data has been developed and their performance tested. Applicability of the proposed protocols is documented in two case studies, spectral density mapping of a uniformly labeled RNA hairpin and of a selectively labeled disaccharide exhibiting highly anisotropic tumbling. Combination of auto- and cross-correlated relaxation data acquired at three magnetic fields was applied in the former case in order to separate effects of fast motions and conformational or chemical exchange. An approach using auto-correlated relaxation rates acquired at five magnetic fields, applicable to anisotropically moving molecules, was used in the latter case. The results were compared with a more advanced analysis of data obtained by interpolation of auto-correlated relaxation rates measured at seven magnetic fields, and with the spectral density mapping of cross-correlated relaxation rates. The results showed that sufficiently accurate values of auto- and cross-correlated spectral density functions at zero and 13C frequencies can be obtained from data acquired at three magnetic fields for uniformly 13C -labeled molecules with a moderate anisotropy of the rotational diffusion tensor. Analysis of auto-correlated relaxation rates at five magnetic fields represents an alternative for molecules undergoing highly anisotropic motions.

SU-C-213-02: Characterizing 3D Printing in the Fabrication of Variable Density Phantoms

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

Madamesila, J; McGeachy, P; Villarreal-Barajas, J

Purpose: In this work, we present characterization, process flow, quality control and application of 3D fabricated low density phantoms for radiotherapy quality assurance. Methods: A Rostock delta 3D printer using polystyrene filament of diameter 1.75 mm was used to print geometric volumes of 2×2×1 cm{sup 3} of varying densities. The variable densities of 0.1 to 0.75 g/cm {sup 3} were created by modulating the infill. A computed tomography (CT) scan was performed to establish an infill-density calibration curve as well as characterize the quality of the print such as uniformity and the infill pattern. The time required to print thesemore » volumes was also recorded. Using the calibration, two low density cones (0.19, 0.52 g/cm{sup 3}) were printed and benchmarked against commercially available phantoms. The dosimetric validation of the low density scaling of Anisotropic Analytical Algorithm (AAA) was performed by using a 0.5 g/cm{sup 3} slab of 10×10×2.4 cm{sup 3} with EBT3 GafChromic film. The gamma analysis at 3%/3mm criteria were compared for the measured and computed dose planes. Results: Analysis of the volume of air pockets in the infill resulted in a reasonable uniformity for densities 0.4 to 0.75 g/cm{sup 3}. Printed phantoms with densities below 0.4 g/cm{sup 3} exhibited a higher ratio of air to polystyrene resulting in large non-uniformity. Compared to the commercial inserts, good agreement was observed only for the printed 0.52 g/cm{sup 3} cone. Dosimetric comparison for a printed low density volume placed in-between layers of solid water resulted in >95% gamma agreement between AAA calculated dose planes and measured EBT3 films for a 6MV 5×5 cm{sup 2} clinical beam. The comparison showed disagreement in the penumbra region. Conclusion: In conclusion, 3D printing technology opens the door to desktop fabrication of variable density phantoms at economical prices in an efficient manner for the quality assurance needs of a small clinic.« less

A bottom up approach to on-road CO2 emissions estimates: improved spatial accuracy and applications for regional planning.

PubMed

Gately, Conor K; Hutyra, Lucy R; Wing, Ian Sue; Brondfield, Max N

2013-03-05

On-road transportation is responsible for 28% of all U.S. fossil-fuel CO2 emissions. Mapping vehicle emissions at regional scales is challenging due to data limitations. Existing emission inventories use spatial proxies such as population and road density to downscale national or state-level data. Such procedures introduce errors where the proxy variables and actual emissions are weakly correlated, and limit analysis of the relationship between emissions and demographic trends at local scales. We develop an on-road emission inventory product for Massachusetts-based on roadway-level traffic data obtained from the Highway Performance Monitoring System (HPMS). We provide annual estimates of on-road CO2 emissions at a 1 × 1 km grid scale for the years 1980 through 2008. We compared our results with on-road emissions estimates from the Emissions Database for Global Atmospheric Research (EDGAR), with the Vulcan Product, and with estimates derived from state fuel consumption statistics reported by the Federal Highway Administration (FHWA). Our model differs from FHWA estimates by less than 8.5% on average, and is within 5% of Vulcan estimates. We found that EDGAR estimates systematically exceed FHWA by an average of 22.8%. Panel regression analysis of per-mile CO2 emissions on population density at the town scale shows a statistically significant correlation that varies systematically in sign and magnitude as population density increases. Population density has a positive correlation with per-mile CO2 emissions for densities below 2000 persons km(-2), above which increasing density correlates negatively with per-mile emissions.

Spatial distribution of marine fishes along a cross-shelf gradient containing a continuum of mangrove seagrass coral reefs off southwestern Puerto Rico

NASA Astrophysics Data System (ADS)

Aguilar-Perera, Alfonso; Appeldoorn, Richard S.

2008-01-01

Despite an extensive study of the fish community off southwestern Puerto Rico, little information is available on the fish spatial distribution along an inshore-offshore, cross-shelf gradient containing a continuum of mangrove-seagrass-coral reefs. We investigated the spatial distribution of reef-associated fish species using a stratified sampling procedure. A total of 52,138 fishes were recorded, representing 102 species belonging to 32 families. Significant differences in mean fish density were evident among strata. Mean densities at shallow fore reefs and deep fore reefs (Romero key) were significantly higher compared to the rest of strata along the gradient. Mean densities of fishes in mangroves and seagrass (Montalva Bay) were comparable to those at shallow back reefs and deep fore reefs offshore (Turrumote), but lower to those inshore (Romero); the lowest fish densities were found in mangroves and seagrass (Montalva Bay) and seagrass (Romero and Corral). At least 17 species, in 7 families, were among the most common in terms of relative abundance representing 76% of the total individuals sampled. A detrended correspondence analysis (DCA) applied to more abundant fish species showed a spatial pattern in density distribution. Three major groupings were evident corresponding to mangroves and seagrass (Montalva Bay), shallow and deep reefs (Romero), and shallow and deep reefs (Corral and Turrumote). A cluster analysis on mean fish densities of the more abundant species revealed a consistent spatial distribution according to biotope by separating the ichthyofauna associated with mangroves, seagrass and that of shallow (back and fore) reefs, and deep fore reefs.

Local breast density assessment using reacquired mammographic images.

PubMed

García, Eloy; Diaz, Oliver; Martí, Robert; Diez, Yago; Gubern-Mérida, Albert; Sentís, Melcior; Martí, Joan; Oliver, Arnau

2017-08-01

The aim of this paper is to evaluate the spatial glandular volumetric tissue distribution as well as the density measures provided by Volpara™ using a dataset composed of repeated pairs of mammograms, where each pair was acquired in a short time frame and in a slightly changed position of the breast. We conducted a retrospective analysis of 99 pairs of repeatedly acquired full-field digital mammograms from 99 different patients. The commercial software Volpara™ Density Maps (Volpara Solutions, Wellington, New Zealand) is used to estimate both the global and the local glandular tissue distribution in each image. The global measures provided by Volpara™, such as breast volume, volume of glandular tissue, and volumetric breast density are compared between the two acquisitions. The evaluation of the local glandular information is performed using histogram similarity metrics, such as intersection and correlation, and local measures, such as statistics from the difference image and local gradient correlation measures. Global measures showed a high correlation (breast volume R=0.99, volume of glandular tissue R=0.94, and volumetric breast density R=0.96) regardless the anode/filter material. Similarly, histogram intersection and correlation metric showed that, for each pair, the images share a high degree of information. Regarding the local distribution of glandular tissue, small changes in the angle of view do not yield significant differences in the glandular pattern, whilst changes in the breast thickness between both acquisition affect the spatial parenchymal distribution. This study indicates that Volpara™ Density Maps is reliable in estimating the local glandular tissue distribution and can be used for its assessment and follow-up. Volpara™ Density Maps is robust to small variations of the acquisition angle and to the beam energy, although divergences arise due to different breast compression conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

High cell density suppresses BMP4-induced differentiation of human pluripotent stem cells to produce macroscopic spatial patterning in a unidirectional perfusion culture chamber.

PubMed

Tashiro, Shota; Le, Minh Nguyen Tuyet; Kusama, Yuta; Nakatani, Eri; Suga, Mika; Furue, Miho K; Satoh, Taku; Sugiura, Shinji; Kanamori, Toshiyuki; Ohnuma, Kiyoshi

2018-04-19

Spatial pattern formation is a critical step in embryogenesis. Bone morphogenetic protein 4 (BMP4) and its inhibitors are major factors for the formation of spatial patterns during embryogenesis. However, spatial patterning of the human embryo is unclear because of ethical issues and isotropic culture environments resulting from conventional culture dishes. Here, we utilized human pluripotent stem cells (hiPSCs) and a simple anisotropic (unidirectional perfusion) culture chamber, which creates unidirectional conditions, to measure the cell community effect. The influence of cell density on BMP4-induced differentiation was explored during static culture using a conventional culture dish. Immunostaining of the early differentiation marker SSEA-1 and the mesendoderm marker BRACHYURY revealed that high cell density suppressed differentiation, with small clusters of differentiated and undifferentiated cells formed. Addition of five-fold higher concentration of BMP4 showed similar results, suggesting that suppression was not caused by depletion of BMP4 but rather by high cell density. Quantitative RT-PCR array analysis showed that BMP4 induced multi-lineage differentiation, which was also suppressed under high-density conditions. We fabricated an elongated perfusion culture chamber, in which proteins were transported unidirectionally, and hiPSCs were cultured with BMP4. At low density, the expression was the same throughout the chamber. However, at high density, SSEA-1 and BRACHYURY were expressed only in upstream cells, suggesting that some autocrine/paracrine factors inhibited the action of BMP4 in downstream cells to form the spatial pattern. Human iPSCs cultured in a perfusion culture chamber might be useful for studying in vitro macroscopic pattern formation in human embryogenesis. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

A comparative study of noise pollution levels in some selected areas in Ilorin Metropolis, Nigeria.

PubMed

Oyedepo, Olayinka S; Saadu, Abdullahi A

2009-11-01

The noise pollution is a major problem for the quality of life in urban areas. This study was conducted to compare the noise pollution levels at busy roads/road junctions, passengers loading parks, commercial, industrial and residential areas in Ilorin metropolis. A total number of 47-locations were selected within the metropolis. Statistical analysis shows significant difference (P < 0.05) in noise pollution levels between industrial areas and low density residential areas, industrial areas and high density areas, industrial areas and passengers loading parks, industrial areas and commercial areas, busy roads/road junctions and low density areas, passengers loading parks and commercial areas and commercial areas and low density areas. There is no significant difference (P > 0.05) in noise pollution levels between industrial areas and busy roads/road junctions, busy roads/road junctions and high density areas, busy roads/road junctions and passengers loading parks, busy roads/road junctions and commercial areas, passengers loading parks and high density areas, passengers loading parks and commercial areas and commercial areas and high density areas. The results show that Industrial areas have the highest noise pollution levels (110.2 dB(A)) followed by busy roads/Road junctions (91.5 dB(A)), Passengers loading parks (87.8 dB(A)) and Commercial areas (84.4 dB(A)). The noise pollution levels in Ilorin metropolis exceeded the recommended level by WHO at 34 of 47 measuring points. It can be concluded that the city is environmentally noise polluted and road traffic and industrial machineries are the major sources of it. Noting the noise emission standards, technical control measures, planning and promoting the citizens awareness about the high noise risk may help to relieve the noise problem in the metropolis.

Branch xylem density variations across the Amazon Basin

NASA Astrophysics Data System (ADS)

Patiño, S.; Lloyd, J.; Paiva, R.; Baker, T. R.; Quesada, C. A.; Mercado, L. M.; Schmerler, J.; Schwarz, M.; Santos, A. J. B.; Aguilar, A.; Czimczik, C. I.; Gallo, J.; Horna, V.; Hoyos, E. J.; Jimenez, E. M.; Palomino, W.; Peacock, J.; Peña-Cruz, A.; Sarmiento, C.; Sota, A.; Turriago, J. D.; Villanueva, B.; Vitzthum, P.; Alvarez, E.; Arroyo, L.; Baraloto, C.; Bonal, D.; Chave, J.; Costa, A. C. L.; Herrera, R.; Higuchi, N.; Killeen, T.; Leal, E.; Luizão, F.; Meir, P.; Monteagudo, A.; Neil, D.; Núñez-Vargas, P.; Peñuela, M. C.; Pitman, N.; Priante Filho, N.; Prieto, A.; Panfil, S. N.; Rudas, A.; Salomão, R.; Silva, N.; Silveira, M.; Soares Dealmeida, S.; Torres-Lezama, A.; Vásquez-Martínez, R.; Vieira, I.; Malhi, Y.; Phillips, O. L.

2009-04-01

Xylem density is a physical property of wood that varies between individuals, species and environments. It reflects the physiological strategies of trees that lead to growth, survival and reproduction. Measurements of branch xylem density, ρx, were made for 1653 trees representing 598 species, sampled from 87 sites across the Amazon basin. Measured values ranged from 218 kg m-3 for a Cordia sagotii (Boraginaceae) from Mountagne de Tortue, French Guiana to 1130 kg m-3 for an Aiouea sp. (Lauraceae) from Caxiuana, Central Pará, Brazil. Analysis of variance showed significant differences in average ρx across regions and sampled plots as well as significant differences between families, genera and species. A partitioning of the total variance in the dataset showed that species identity (family, genera and species) accounted for 33% with environment (geographic location and plot) accounting for an additional 26%; the remaining "residual" variance accounted for 41% of the total variance. Variations in plot means, were, however, not only accountable by differences in species composition because xylem density of the most widely distributed species in our dataset varied systematically from plot to plot. Thus, as well as having a genetic component, branch xylem density is a plastic trait that, for any given species, varies according to where the tree is growing in a predictable manner. Within the analysed taxa, exceptions to this general rule seem to be pioneer species belonging for example to the Urticaceae whose branch xylem density is more constrained than most species sampled in this study. These patterns of variation of branch xylem density across Amazonia suggest a large functional diversity amongst Amazonian trees which is not well understood.

Change in cortical bone density and its distribution differs between boys and girls during puberty.

PubMed

Kontulainen, Saija A; Macdonald, Heather M; McKay, Heather A

2006-07-01

Postmenarchal girls and premenopausal women have 3-4% higher cortical bone density (CoD, milligrams per cubic centimeter), compared with postpubertal boys and men, respectively. Females' denser cortical bone is thought to serve as a calcium reservoir for reproductive needs. However, prospective data are lacking that describe CoD development and bone mineral density distribution during puberty in both sexes. Thus, our objectives were to assess maturity and sex differences in the 20-month change of CoD and radial distribution of bone mineral density (RDBMD, milligrams per cubic centimeter) in early-, peri-, and postpubertal girls and boys. Maturity groups were based on change in menarcheal status (girls, n = 68) and pubic hair stage (Tanner) (boys, n = 59). Peripheral quantitative computed tomography was used to measure CoD and RDBMD at the tibial middiaphysis. The increase in average CoD was 1.9% [22.8 mg/cm(3); 95% confidence interval (CI), 10-36], 2.8% (33.8 mg/cm(3); 95% CI, 21-47), and 1.5% (55.0 mg/cm(3); 95% CI, 17-93) greater in early, peri-, and postpubertal girls, compared with boys, respectively. Analysis of RDBMD revealed that the change in density distribution varied across pubertal groups in girls. Across puberty, all girls showed an increase in the high density midcortical region, whereas only peripubertal girls showed an increase in the lower density subcortical region. A sex-difference in RDBMD change was noted within early and peripubertal groups. Our findings of sexual dimorphism in CoD development give support to the hypothesis that female bone deposits calcium for reproductive needs by consolidation of cortical bone during puberty.

Gold nanoparticles with different capping systems: an electronic and structural XAS analysis.

PubMed

López-Cartes, C; Rojas, T C; Litrán, R; Martínez-Martínez, D; de la Fuente, J M; Penadés, S; Fernández, A

2005-05-12

Gold nanoparticles (NPs) have been prepared with three different capping systems: a tetralkylammonium salt, an alkanethiol, and a thiol-derivatized neoglycoconjugate. Also gold NPs supported on a porous TiO(2) substrate have been investigated. X-ray absorption spectroscopy (XAS) has been used to determine the electronic behavior of the different capped/supported systems regarding the electron/hole density of d states. Surface and size effects, as well as the role of the microstructure, have been also studied through an exhaustive analysis of the EXAFS (extended X-ray absorption fine structure) data. Very small gold NPs functionalized with thiol-derivatized molecules show an increase in d-hole density at the gold site due to Au-S charge transfer. This effect is overcoming size effects (which lead to a slightly increase of the d-electron density) for high S:Au atomic ratios and core-shell microstructures where an atomically abrupt Au-S interface likely does not exist. It has been also shown that thiol functionalization of very small gold NPs is introducing a strong distortion as compared to fcc order. To the contrary, electron transfer from reduced support oxides to gold NPs can produce a higher increase in d-electron density at the gold site, as compared to naked gold clusters.

Automated mammographic breast density estimation using a fully convolutional network.

PubMed

Lee, Juhun; Nishikawa, Robert M

2018-03-01

The purpose of this study was to develop a fully automated algorithm for mammographic breast density estimation using deep learning. Our algorithm used a fully convolutional network, which is a deep learning framework for image segmentation, to segment both the breast and the dense fibroglandular areas on mammographic images. Using the segmented breast and dense areas, our algorithm computed the breast percent density (PD), which is the faction of dense area in a breast. Our dataset included full-field digital screening mammograms of 604 women, which included 1208 mediolateral oblique (MLO) and 1208 craniocaudal (CC) views. We allocated 455, 58, and 91 of 604 women and their exams into training, testing, and validation datasets, respectively. We established ground truth for the breast and the dense fibroglandular areas via manual segmentation and segmentation using a simple thresholding based on BI-RADS density assessments by radiologists, respectively. Using the mammograms and ground truth, we fine-tuned a pretrained deep learning network to train the network to segment both the breast and the fibroglandular areas. Using the validation dataset, we evaluated the performance of the proposed algorithm against radiologists' BI-RADS density assessments. Specifically, we conducted a correlation analysis between a BI-RADS density assessment of a given breast and its corresponding PD estimate by the proposed algorithm. In addition, we evaluated our algorithm in terms of its ability to classify the BI-RADS density using PD estimates, and its ability to provide consistent PD estimates for the left and the right breast and the MLO and CC views of the same women. To show the effectiveness of our algorithm, we compared the performance of our algorithm against a state of the art algorithm, laboratory for individualized breast radiodensity assessment (LIBRA). The PD estimated by our algorithm correlated well with BI-RADS density ratings by radiologists. Pearson's rho values of our algorithm for CC view, MLO view, and CC-MLO-averaged were 0.81, 0.79, and 0.85, respectively, while those of LIBRA were 0.58, 0.71, and 0.69, respectively. For CC view and CC-MLO averaged cases, the difference in rho values between the proposed algorithm and LIBRA showed statistical significance (P < 0.006). In addition, our algorithm provided reliable PD estimates for the left and the right breast (Pearson's ρ > 0.87) and for the MLO and CC views (Pearson's ρ = 0.76). However, LIBRA showed a lower Pearson's rho value (0.66) for both the left and right breasts for the CC view. In addition, our algorithm showed an excellent ability to separate each sub BI-RADS breast density class (statistically significant, p-values = 0.0001 or less); only one comparison pair, density 1 and density 2 in the CC view, was not statistically significant (P = 0.54). However, LIBRA failed to separate breasts in density 1 and 2 for both the CC and MLO views (P > 0.64). We have developed a new deep learning based algorithm for breast density segmentation and estimation. We showed that the proposed algorithm correlated well with BI-RADS density assessments by radiologists and outperformed an existing state of the art algorithm. © 2018 American Association of Physicists in Medicine.

Boundary layers at the interface of two different shear flows

NASA Astrophysics Data System (ADS)

Weidman, Patrick D.; Wang, C. Y.

2018-05-01

We present solutions for the boundary layer between two uniform shear flows flowing in the same direction. In the upper layer, the flow has shear strength a, fluid density ρ1, and kinematic viscosity ν1, while the lower layer has shear strength b, fluid density ρ2, and kinematic viscosity ν2. Similarity transformations reduce the boundary-layer equations to a pair of ordinary differential equations governed by three dimensionless parameters: the shear strength ratio γ = b/a, the density ratio ρ = ρ2/ρ1, and the viscosity ratio ν = ν2/ν1. Further analysis shows that an affine transformation reduces this multi-parameter problem to a single ordinary differential equation which may be efficiently integrated as an initial-value problem. Solutions of the original boundary-value problem are shown to agree with the initial-value integrations, but additional dual and quadruple solutions are found using this method. We argue on physical grounds and through bifurcation analysis that these additional solutions are not tenable. The present problem is applicable to the trailing edge flow over a thin airfoil with camber.

Electrostatic properties of the pyrimethamine-2,4-dihydroxybenzoic acid cocrystal in methanol studied using transferred electron-density parameters.

PubMed

Faroque, Muhammad Umer; Noureen, Sajida; Ahmed, Maqsood; Tahir, Muhammad Nawaz

2018-01-01

The crystal structure of the cocrystal salt form of the antimalarial drug pyrimethamine with 2,4-dihydroxybenzoic acid in methanol [systematic name: 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium 2,4-dihydroxybenzoate methanol monosolvate, C 12 H 14 ClN 4 + ·C 7 H 5 O 4 - ·CH 3 OH] has been studied using X-ray diffraction data collected at room temperature. The crystal structure was refined using the classical Independent Atom Model (IAM) and the Multipolar Atom Model by transferring electron-density parameters from the ELMAM2 database. The Cl atom was refined anharmonically. The results of both refinement methods have been compared. The intermolecular interactions have been characterized on the basis of Hirshfeld surface analysis and topological analysis using Bader's theory of Atoms in Molecules. The results show that the molecular assembly is built primarily on the basis of charge transfer between 2,4-dihydroxybenzoic acid and pyrimethamine, which results in strong intermolecular hydrogen bonds. This fact is further validated by the calculation of the electrostatic potential based on transferred electron-density parameters.

Intrinsic physical conditions and structure of relativistic jets in active galactic nuclei

NASA Astrophysics Data System (ADS)

Nokhrina, E. E.; Beskin, V. S.; Kovalev, Y. Y.; Zheltoukhov, A. A.

2015-03-01

The analysis of the frequency dependence of the observed shift of the cores of relativistic jets in active galactic nuclei (AGNs) allows us to evaluate the number density of the outflowing plasma ne and, hence, the multiplicity parameter λ = ne/nGJ, where nGJ is the Goldreich-Julian number density. We have obtained the median value for λmed = 3 × 1013 and the median value for the Michel magnetization parameter σM, med = 8 from an analysis of 97 sources. Since the magnetization parameter can be interpreted as the maximum possible Lorentz factor Γ of the bulk motion which can be obtained for relativistic magnetohydrodynamic (MHD) flow, this estimate is in agreement with the observed superluminal motion of bright features in AGN jets. Moreover, knowing these key parameters, one can determine the transverse structure of the flow. We show that the poloidal magnetic field and particle number density are much larger in the centre of the jet than near the jet boundary. The MHD model can also explain the typical observed level of jet acceleration. Finally, casual connectivity of strongly collimated jets is discussed.

Hybrid thermionic-photovoltaic converter

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

Datas, A.

2016-04-04

A conceptual device for the direct conversion of heat into electricity is presented. This concept hybridizes thermionic (TI) and thermophotovoltaic (TPV) energy conversion in a single thermionic-photovoltaic (TIPV) solid-state device. This device transforms into electricity both the electron and photon fluxes emitted by an incandescent surface. This letter presents an idealized analysis of this device in order to determine its theoretical potential. According to this analysis, the key advantage of this converter, with respect to either TPV or TI, is the higher power density in an extended temperature range. For low temperatures, TIPV performs like TPV due to the negligiblemore » electron flux. On the contrary, for high temperatures, TIPV performs like TI due to the great enhancement of the electron flux, which overshadows the photon flux contribution. At the intermediate temperatures, ∼1650 K in the case of this particular study, I show that the power density potential of TIPV converter is twice as great as that of TPV and TI. The greatest impact concerns applications in which the temperature varies in a relatively wide range, for which averaged power density enhancement above 500% is attainable.« less

A theoretical study of structural and electronic properties of pentacene/Al(100) interface.

PubMed

Saranya, G; Nair, Shiny; Natarajan, V; Kolandaivel, P; Senthilkumar, K

2012-09-01

The first principle calculations within the framework of density functional theory have been performed for the pentacene molecule deposited on the aluminum Al(100) substrate to study the structural and electronic properties of the pentacene/Al(100) interface. The most stable configuration was found at bridge site with 45° rotation of the pentacene molecule on Al(100) surface with a vertical distance of 3.4 Å within LDA and 3.8 Å within GGA functionals. The calculated adsorption energy reveals that the adsorption of pentacene molecule on Al(100) surface is physisorption. For the stable adsorption geometry the electronic properties such as density of states (DOS), partial density of states (PDOS), Mulliken population analysis and Schottky barrier height are studied. The analysis of atomic charge, DOS and PDOS show that the charge is transferred from the Al(100) surface to pentacene molecule, and the transferred charge is about -0.05 electrons. For the adsorbed system, the calculated Schottky barrier height for hole and electron transport is 0.27 and 1.55 eV, respectively. Copyright © 2012 Elsevier Inc. All rights reserved.

Association between mammogram density and background parenchymal enhancement of breast MRI

NASA Astrophysics Data System (ADS)

Aghaei, Faranak; Danala, Gopichandh; Wang, Yunzhi; Zarafshani, Ali; Qian, Wei; Liu, Hong; Zheng, Bin

2018-02-01

Breast density has been widely considered as an important risk factor for breast cancer. The purpose of this study is to examine the association between mammogram density results and background parenchymal enhancement (BPE) of breast MRI. A dataset involving breast MR images was acquired from 65 high-risk women. Based on mammography density (BIRADS) results, the dataset was divided into two groups of low and high breast density cases. The Low-Density group has 15 cases with mammographic density (BIRADS 1 and 2), while the High-density group includes 50 cases, which were rated by radiologists as mammographic density BIRADS 3 and 4. A computer-aided detection (CAD) scheme was applied to segment and register breast regions depicted on sequential images of breast MRI scans. CAD scheme computed 20 global BPE features from the entire two breast regions, separately from the left and right breast region, as well as from the bilateral difference between left and right breast regions. An image feature selection method namely, CFS method, was applied to remove the most redundant features and select optimal features from the initial feature pool. Then, a logistic regression classifier was built using the optimal features to predict the mammogram density from the BPE features. Using a leave-one-case-out validation method, the classifier yields the accuracy of 82% and area under ROC curve, AUC=0.81+/-0.09. Also, the box-plot based analysis shows a negative association between mammogram density results and BPE features in the MRI images. This study demonstrated a negative association between mammogram density and BPE of breast MRI images.

Inventory shows extent of non-native invasive plants in Minnesota forests

Treesearch

W. Keith Moser; Mark D. Nelson; Mark H. Hansen

2009-01-01

Readers are no doubt aware of the impact that non-native invasive plants (NNIP) present to Minnesota's ecosystems. The U.S. Forest Service's Northern Research Station (NRS) Forest Inventory and Analysis (FIA) Program is studying what determines where these plants are found, including forest type, tree density, disturbance, productivity, and topography.

PDF-based heterogeneous multiscale filtration model.

PubMed

Gong, Jian; Rutland, Christopher J

2015-04-21

Motivated by modeling of gasoline particulate filters (GPFs), a probability density function (PDF) based heterogeneous multiscale filtration (HMF) model is developed to calculate filtration efficiency of clean particulate filters. A new methodology based on statistical theory and classic filtration theory is developed in the HMF model. Based on the analysis of experimental porosimetry data, a pore size probability density function is introduced to represent heterogeneity and multiscale characteristics of the porous wall. The filtration efficiency of a filter can be calculated as the sum of the contributions of individual collectors. The resulting HMF model overcomes the limitations of classic mean filtration models which rely on tuning of the mean collector size. Sensitivity analysis shows that the HMF model recovers the classical mean model when the pore size variance is very small. The HMF model is validated by fundamental filtration experimental data from different scales of filter samples. The model shows a good agreement with experimental data at various operating conditions. The effects of the microstructure of filters on filtration efficiency as well as the most penetrating particle size are correctly predicted by the model.

Femoral Neck X-Ray Absorptiometry Parameters and Peripheral Quantitative Computer Tomography Tibial Cortical Density Predict Survival in Dialysis Patients.

PubMed

Yap, Natalie; Wong, Phillip; McGinn, Stella; Nery, Maria-Liza; Doyle, Jean; Wells, Lynda; Clifton-Bligh, Phillip; Clifton-Bligh, Roderick J

2017-01-01

Low bone mineral density (BMD) is a known independent predictor of mortality in the general elderly population. However, studies in patients with end-stage renal disease (ESRD) are limited. The present study evaluated mortality during long-term follow-up in a population of patients having dialysis for ESRD, in whom BMD was also measured. Fifty-eight patients with ESRD were recruited consecutively from a dialysis clinic and followed prospectively for 6 years. Baseline BMD of the lumbar spine and femoral neck (FN) were measured by X-ray absorptiometry and by peripheral quantitative CT at the radius and tibia. Serum calcium, phosphate, parathyroid hormone (PTH), and albumin were measured at baseline. During follow-up, 25 patients died. Univariate analysis showed that mortality was significantly associated with FN-BMD: hazards ratio (HR) per 0.1 g/cm2 decrease 1.50 (95% CI 1.07-2.10), p = 0.019; FN-T score: HR per 1-SD decrease 1.84 (95% CI 1.16-2.92), p = 0.009; and tibial cortical density: HR per 10 mg/cm3 decrease 1.08 (95% CI 1.02-1.14), p = 0.010. In multivariate analysis with stepwise adjustment for age, sex, transplant status, albumin, PTH, phosphate, dialysis duration, diabetes, and smoking, FN-T score remained significantly associated with mortality: HR per 1-SD decrease 1.82 (95% CI 1.02-3.24), p = 0.044, whereas the HR for FN-BMD and tibial cortical density were no longer significant. When 4 patients who had peritoneal dialysis were excluded, the HR relating FN-BMD, FN-T score, and tibial cortical density to mortality remained significant but became insignificant when albumin was included in the multivariate analysis. Reduced FN-BMD, FN-T score, and tibial cortical density were significantly associated with an increased risk of death in patients with ESRD. © 2017 S. Karger AG, Basel.

No Flares from Gamma-Ray Burst Afterglow Blast Waves Encountering Sudden Circumburst Density Change

NASA Astrophysics Data System (ADS)

Gat, Ilana; van Eerten, Hendrik; MacFadyen, Andrew

2013-08-01

Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power-law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreading, collimation, and edge effects of the blast wave as it encounters the change in circumburst medium. In all cases considered in this paper, we find that a flare will not be observed for any of the density changes studied.

Associated macrozoobenthos with the invasive Asian clam Corbicula fluminea

NASA Astrophysics Data System (ADS)

Ilarri, Martina I.; Freitas, Fabiana; Costa-Dias, Sérgia; Antunes, Carlos; Guilhermino, Lúcia; Sousa, Ronaldo

2012-08-01

The Asian clam Corbicula fluminea is one of the most invasive species in brackish and freshwater ecosystems. In the Minho estuary (NW of the Iberian Peninsula) this invasive species can reach densities up to 4000 ind m- 2, occurring over large areas. C. fluminea can significantly alter the physical structure of the benthic environment, and the structure and functioning of this estuarine community. In this context, this work aimed to evaluate the correlation of different densities of C. fluminea on the macrozoobenthos across five sites in the Minho estuary during three distinct periods of 2009 (winter, spring and summer). The comparative analysis indicate that macrozoobenthic density, biomass and diversity positively respond to increasing density of C. fluminea, with abiotic conditions also playing an important role in the observed patterns, both in brackish and freshwater settings. Crustacea, Insecta and Gastropoda are the main faunal groups responding positively to C. fluminea increasing density. The mechanisms responsible for these positive trends still needs to be established although engineering activities and the increase in waste products may play essential roles. Nevertheless, despite such positive effects, earlier studies have showed that the density, biomass and spatial distribution of some species, especially native bivalves dramatically decreased after C. fluminea introduction.

Determination of fluid extraction and osmotic conductance sigma K in the lung with hypertonic NaCl infusion. I. Theory.

PubMed

Hunter, M; Lee, J

1992-11-01

A dispersion and extraction model of the lung is developed to assess how the infusion of hypertonic saline into the pulmonary artery changes the gravimetric density of pulmonary venous blood. The dispersion analysis is built on the indicator dilution curve measured for the pulmonary circulation. The extraction model consists of microvascular and interstitial compartments separated by a permeable pulmonary endothelium. Because the density of fluid extracted by the hypertonic disturbance is lower than the blood density, the extraction leads to a decrease in blood density. Two cases of fluid extraction are analyzed, a hypertonic infusion to elevate the osmotic pressure in the pulmonary arterial blood in the form of a step function and an infusion performed over a period of 1 sec. Both cases show that the dispersion significantly attenuates the changes in osmotic pressure and density as they are transported by the blood along the pulmonary vasculature. Because the model has taken into account the effect of dispersion and pulmonary blood flow, the equations developed here provide the basis to calculate from the density change in pulmonary venous blood the characteristics of osmotic extraction intrinsic to the lung.

Permeability analysis of Asbuton material used as core layers of water resistance in the body of dam

NASA Astrophysics Data System (ADS)

Rahim, H.; Tjaronge, M. W.; Thaha, A.; Djamaluddin, R.

2017-11-01

In order to increase consumption of the local materials and national products, large reserves of Asbuton material about 662.960 million tons in the Buton Islands became an alternative as a waterproof core layer in the body of dam. The Asbuton material was used in this research is Lawele Granular Asphalt (LGA). This study was an experimental study conducted in the laboratory by conducting density testing (content weight) and permeability on Asbuton material. Testing of the Asbuton material used Falling Head method to find out the permeability value of Asbuton material. The data of test result to be analyzed are the relation between compaction energy and density value also relation between density value and permeability value of Asbuton material. The result shows that increases the number of blow apply to the Asbuton material at each layer will increase the density of the Asbuton material. The density value of Asbuton material that satisfies the requirements for use as an impermeable core layer in the dam body is 1.53 grams/cm3. The increase the density value (the weight of the contents) of the Asbuton material will reduce its permeability value of the Asbuton material.

Total bone calcium in normal women: effect of age and menopause status

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

Gallagher, J.C.; Goldgar, D.; Moy, A.

1987-12-01

Bone density in different regions of the skeleton was measured in 392 normal women aged 20-80 years by dual photon absorpiometry. In premenopausal women, aged 25-50 years, multiple regression analysis of regional bone density on age, height, and weight showed a small significant decrease in total bone density (less than 0.01) but no significant change in other regions of the skeleton. In postmenopausal women there were highly significant decreases in all regions of the skeleton (p less than 0.001), and bone density in these areas decreased as a logarithmic function of years since menopause. Based on multiple regression analyses, themore » decrease in spine density and total bone calcium was 2.5-3.0 times greater in the 25 years after menopause than the 25 years before menopause. The largest change, however, occurred in the first five years after menopause. During this time the estimated annual change in spine density and total bone calcium was about 10 times greater than that in the premenopausal period. These results demonstrate the important effect of the menopause in determining bone mass in later life.« less

Density-Gradient-Driven trapped-electron-modes in improved-confinement RFP plasmas

NASA Astrophysics Data System (ADS)

Duff, James; Sarff, John; Ding, Weixing; Brower, David; Parke, Eli; Chapman, Brett; Terry, Paul; Pueschel, M. J.; Williams, Zach

2017-10-01

Short wavelength density fluctuations in improved-confinement MST plasmas exhibit multiple features characteristic of the trapped-electron-mode (TEM). Core transport in the RFP is normally governed by magnetic stochasticity stemming from long wavelength tearing modes that arise from current profile peaking, which are suppressed via inductive control for this work. The improved confinement is associated with an increase in the pressure gradient that can destabilize drift waves. The measured density fluctuations have f 50 kHz, kϕρs < 0.14 , and propagate in the electron drift direction. Their spectral emergence coincides with a sharp decrease in global tearing mode associated fluctuations, their amplitude increases with local density gradient, and they exhibit a density-gradient threshold at R /Ln 15 . The GENE code, modified for the RFP, predicts the onset of density-gradient-driven TEM for these strong-gradient plasma conditions. While nonlinear analysis shows a large Dimits shift associated with predicted strong zonal flows, the inclusion of residual magnetic fluctuations, comparable to experimental magnetic fluctuations, causes a collapse of the zonal flows and an increase in the predicted transport to a level close to the experimentally measured heat flux. Work supported by US DOE.

Extended MHD modeling of tearing-driven magnetic relaxation

NASA Astrophysics Data System (ADS)

Sauppe, J. P.; Sovinec, C. R.

2017-05-01

Discrete relaxation events in reversed-field pinch relevant configurations are investigated numerically with nonlinear extended magnetohydrodynamic (MHD) modeling, including the Hall term in Ohm's law and first-order ion finite Larmor radius effects. Results show variability among relaxation events, where the Hall dynamo effect may help or impede the MHD dynamo effect in relaxing the parallel current density profile. The competitive behavior arises from multi-helicity conditions where the dominant magnetic fluctuation is relatively small. The resulting changes in parallel current density and parallel flow are aligned in the core, consistent with experimental observations. The analysis of simulation results also confirms that the force density from fluctuation-induced Reynolds stress arises subsequent to the drive from the fluctuation-induced Lorentz force density. Transport of the momentum density is found to be dominated by the fluctuation-induced Maxwell stress over most of the cross section with viscous and gyroviscous contributions being large in the edge region. The findings resolve a discrepancy with respect to the relative orientation of current density and flow relaxation, which had not been realized or investigated in King et al. [Phys. Plasmas 19, 055905 (2012)], where only the magnitude of flow relaxation is actually consistent with experimental results.

Poster — Thur Eve — 15: Improvements in the stability of the tomotherapy imaging beam

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

Belec, J

2014-08-15

Use of helical TomoTherapy based MVCT imaging for adaptive planning requires the image values (HU) to remain stable over the course of treatment. In the past, the image value stability was suboptimal, which required frequent change to the image value to density calibration curve to avoid dose errors on the order of 2–4%. The stability of the image values at our center was recently improved by stabilizing the dose rate of the machine (dose control servo) and performing daily MVCT calibration corrections. In this work, we quantify the stability of the image values over treatment time by comparing patient treatmentmore » image density derived using MVCT and KVCT. The analysis includes 1) MVCT - KVCT density difference histogram, 2) MVCT vs KVCT density spectrum, 3) multiple average profile density comparison and 4) density difference in homogeneous locations. Over two months, the imaging beam stability was compromised several times due to a combination of target wobbling, spectral calibration, target change and magnetron issues. The stability of the image values were analyzed over the same period. Results show that the impact on the patient dose calculation is 0.7% +− 0.6%.« less

Analysis of recoverable current from one component of magnetic flux density in MREIT and MRCDI.

PubMed

Park, Chunjae; Lee, Byung Il; Kwon, Oh In

2007-06-07

Magnetic resonance current density imaging (MRCDI) provides a current density image by measuring the induced magnetic flux density within the subject with a magnetic resonance imaging (MRI) scanner. Magnetic resonance electrical impedance tomography (MREIT) has been focused on extracting some useful information of the current density and conductivity distribution in the subject Omega using measured B(z), one component of the magnetic flux density B. In this paper, we analyze the map Tau from current density vector field J to one component of magnetic flux density B(z) without any assumption on the conductivity. The map Tau provides an orthogonal decomposition J = J(P) + J(N) of the current J where J(N) belongs to the null space of the map Tau. We explicitly describe the projected current density J(P) from measured B(z). Based on the decomposition, we prove that B(z) data due to one injection current guarantee a unique determination of the isotropic conductivity under assumptions that the current is two-dimensional and the conductivity value on the surface is known. For a two-dimensional dominating current case, the projected current density J(P) provides a good approximation of the true current J without accumulating noise effects. Numerical simulations show that J(P) from measured B(z) is quite similar to the target J. Biological tissue phantom experiments compare J(P) with the reconstructed J via the reconstructed isotropic conductivity using the harmonic B(z) algorithm.

Study of subband electronic structure of Si δ-doped GaAs using magnetotransport measurements in tilted magnetic fields

NASA Astrophysics Data System (ADS)

Li, G.; Hauser, N.; Jagadish, C.; Antoszewski, J.; Xu, W.

1996-06-01

Si δ-doped GaAs grown by metal organic vapor phase epitaxy (MOVPE) is characterized using magnetotransport measurements in tilted magnetic fields. Angular dependence of the longitudinal magnetoresistance (Rxx) vs the magnetic field (B) traces in tilted magnetic fields is used to examine the existence of a quasi-two-dimensional electron gas. The subband electron densities (ni) are obtained applying fast Fourier transform (FFT) analysis to the Rxx vs B trace and using mobility spectrum (MS) analysis of the magnetic field dependent Hall data. Our results show that (1) the subband electron densities remain roughly constant when the tilted magnetic field with an angle <30° measured from the Si δ-doped plane normal is ramped up to 13 T; (2) FFT analysis of the Rxx vs B trace and MS analysis of the magnetic field dependent Hall data both give the comparable results on subband electron densities of Si δ-doped GaAs with low δ-doping concentration, however, for Si δ-doped GaAs with very high δ-doping concentration, the occupation of the lowest subbands cannot be well resolved in the MS analysis; (3) the highest subband electron mobility reported to date of 45 282 cm2/s V is observed in Si δ-doped GaAs at 77 K in the dark; and (4) the subband electron densities of Si δ-doped GaAs grown by MOVPE at 700 °C are comparable to those grown by MBE at temperatures below 600 °C. A detailed study of magnetotransport properties of Si δ-doped GaAs in the parallel magnetic fields is then carried out to further confirm the subband electronic structures revealed by FFT and MS analysis. Our results are compared to theoretical calculation previously reported in literature. In addition, influence of different cap layer structures on subband electronic structures of Si δ-doped GaAs is observed and also discussed.

Tracing the Fingerprint of Chemical Bonds within the Electron Densities of Hydrocarbons: A Comparative Analysis of the Optimized and the Promolecule Densities.

PubMed

Keyvani, Zahra Alimohammadi; Shahbazian, Shant; Zahedi, Mansour

2016-10-18

The equivalence of the molecular graphs emerging from the comparative analysis of the optimized and the promolecule electron densities in two hundred and twenty five unsubstituted hydrocarbons was recently demonstrated [Keyvani et al. Chem. Eur. J. 2016, 22, 5003]. Thus, the molecular graph of an optimized molecular electron density is not shaped by the formation of the C-H and C-C bonds. In the present study, to trace the fingerprint of the C-H and C-C bonds in the electron densities of the same set of hydrocarbons, the amount of electron density and its Laplacian at the (3, -1) critical points associated with these bonds are derived from both optimized and promolecule densities, and compared in a newly proposed comparative analysis. The analysis not only conforms to the qualitative picture of the electron density build up between two atoms upon formation of a bond in between, but also quantifies the resulting accumulation of the electron density at the (3, -1) critical points. The comparative analysis also reveals a unified mode of density accumulation in the case of 2318 studied C-H bonds, but various modes of density accumulation are observed in the case of 1509 studied C-C bonds and they are classified into four groups. The four emerging groups do not always conform to the traditional classification based on the bond orders. Furthermore, four C-C bonds described as exotic bonds in previous studies, for example the inverted C-C bond in 1,1,1-propellane, are naturally distinguished from the analysis. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.