An Investigation of Sample Size Splitting on ATFIND and DIMTEST

ERIC Educational Resources Information Center

Socha, Alan; DeMars, Christine E.

2013-01-01

Modeling multidimensional test data with a unidimensional model can result in serious statistical errors, such as bias in item parameter estimates. Many methods exist for assessing the dimensionality of a test. The current study focused on DIMTEST. Using simulated data, the effects of sample size splitting for use with the ATFIND procedure for…

QSAR models for anti-malarial activity of 4-aminoquinolines.

PubMed

Masand, Vijay H; Toropov, Andrey A; Toropova, Alla P; Mahajan, Devidas T

2014-03-01

In the present study, predictive quantitative structure - activity relationship (QSAR) models for anti-malarial activity of 4-aminoquinolines have been developed. CORAL, which is freely available on internet (http://www.insilico.eu/coral), has been used as a tool of QSAR analysis to establish statistically robust QSAR model of anti-malarial activity of 4-aminoquinolines. Six random splits into the visible sub-system of the training and invisible subsystem of validation were examined. Statistical qualities for these splits vary, but in all these cases, statistical quality of prediction for anti-malarial activity was quite good. The optimal SMILES-based descriptor was used to derive the single descriptor based QSAR model for a data set of 112 aminoquinolones. All the splits had r(2)> 0.85 and r(2)> 0.78 for subtraining and validation sets, respectively. The three parametric multilinear regression (MLR) QSAR model has Q(2) = 0.83, R(2) = 0.84 and F = 190.39. The anti-malarial activity has strong correlation with presence/absence of nitrogen and oxygen at a topological distance of six.

Differences in results of analyses of concurrent and split stream-water samples collected and analyzed by the US Geological Survey and the Illinois Environmental Protection Agency, 1985-91

USGS Publications Warehouse

Melching, C.S.; Coupe, R.H.

1995-01-01

During water years 1985-91, the U.S. Geological Survey (USGS) and the Illinois Environmental Protection Agency (IEPA) cooperated in the collection and analysis of concurrent and split stream-water samples from selected sites in Illinois. Concurrent samples were collected independently by field personnel from each agency at the same time and sent to the IEPA laboratory, whereas the split samples were collected by USGS field personnel and divided into aliquots that were sent to each agency's laboratory for analysis. The water-quality data from these programs were examined by means of the Wilcoxon signed ranks test to identify statistically significant differences between results of the USGS and IEPA analyses. The data sets for constituents and properties identified by the Wilcoxon test as having significant differences were further examined by use of the paired t-test, mean relative percentage difference, and scattergrams to determine if the differences were important. Of the 63 constituents and properties in the concurrent-sample analysis, differences in only 2 (pH and ammonia) were statistically significant and large enough to concern water-quality engineers and planners. Of the 27 constituents and properties in the split-sample analysis, differences in 9 (turbidity, dissolved potassium, ammonia, total phosphorus, dissolved aluminum, dissolved barium, dissolved iron, dissolved manganese, and dissolved nickel) were statistically significant and large enough to con- cern water-quality engineers and planners. The differences in concentration between pairs of the concurrent samples were compared to the precision of the laboratory or field method used. The differences in concentration between pairs of the concurrent samples were compared to the precision of the laboratory or field method used. The differences in concentration between paris of split samples were compared to the precision of the laboratory method used and the interlaboratory precision of measuring a given concentration or property. Consideration of method precision indicated that differences between concurrent samples were insignificant for all concentrations and properties except pH, and that differences between split samples were significant for all concentrations and properties. Consideration of interlaboratory precision indicated that the differences between the split samples were not unusually large. The results for the split samples illustrate the difficulty in obtaining comparable and accurate water-quality data.

Anatomy of particle diffusion

NASA Astrophysics Data System (ADS)

Bringuier, E.

2009-11-01

The paper analyses particle diffusion from a thermodynamic standpoint. The main goal of the paper is to highlight the conceptual connection between particle diffusion, which belongs to non-equilibrium statistical physics, and mechanics, which deals with particle motion, at the level of third-year university courses. We start out from the fact that, near equilibrium, particle transport should occur down the gradient of the chemical potential. This yields Fick's law with two additional advantages. First, splitting the chemical potential into 'mechanical' and 'chemical' contributions shows how transport and mechanics are linked through the diffusivity-mobility relationship. Second, splitting the chemical potential into entropic and energetic contributions discloses the respective roles of entropy maximization and energy minimization in driving diffusion. The paper addresses first unary diffusion, where there is only one mobile species in an immobile medium, and next turns to binary diffusion, where two species are mobile with respect to each other in a fluid medium. The interrelationship between unary and binary diffusivities is brought out and it is shown how binary diffusion reduces to unary diffusion in the limit of high dilution of one species amidst the other one. Self- and mutual diffusion are considered and contrasted within the thermodynamic framework; self-diffusion is a time-dependent manifestation of the Gibbs paradox of mixing.

Pharmaceutical counselling about different types of tablet-splitting methods based on the results of weighing tests and mechanical development of splitting devices.

PubMed

Somogyi, O; Meskó, A; Csorba, L; Szabó, P; Zelkó, R

2017-08-30

The division of tablets and adequate methods of splitting them are a complex problem in all sectors of health care. Although tablet-splitting is often required, this procedure can be difficult for patients. Four tablets were investigated with different external features (shape, score-line, film-coat and size). The influencing effect of these features and the splitting methods was investigated according to the precision and "weight loss" of splitting techniques. All four types of tablets were halved by four methods: by hand, with a kitchen knife, with an original manufactured splitting device and with a modified tablet splitter based on a self-developed mechanical model. The mechanical parameters (harness and friability) of the products were measured during the study. The "weight loss" and precision of splitting methods were determined and compared by statistical analysis. On the basis of the results, the external features (geometry), the mechanical parameters of tablets and the mechanical structure of splitting devices can influence the "weight loss" and precision of tablet-splitting. Accordingly, a new decision-making scheme was developed for the selection of splitting methods. In addition, the skills of patients and the specialties of therapy should be considered so that pharmaceutical counselling can be more effective regarding tablet-splitting. Copyright © 2017 Elsevier B.V. All rights reserved.

Excitonic fine-structure splitting in telecom-wavelength InAs/GaAs quantum dots: Statistical distribution and height-dependence

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

Goldmann, Elias, E-mail: goldmann@itp.uni-bremen.de; Barthel, Stefan; Florian, Matthias

The variation of the excitonic fine-structure splitting is studied for semiconductor quantum dots under the influence of a strain-reducing layer, utilized to shift the emission wavelength of the excitonic transition into the telecom-wavelength regime of 1.3–1.5 μm. By means of a sp{sup 3}s{sup *}-tight-binding model and configuration interaction, we calculate wavelength shifts and fine-structure splittings for various quantum dot geometries. We find the splittings remaining small and even decreasing with strain-reducing layer composition for quantum dots with large height. Combined with an observed increased emission efficiency, the applicability for generation of entanglement photons is persistent.

[Divisibility of warfarin and fluindione tablets tested in elderly patients and their family circle].

PubMed

Pautas, Eric; Despres, Jérémie; Peyron, Isabelle; Golmard, Jean-Louis; Grange, Jennifer; Koenig, Nelly; Gouronnec, Adeline; Mitha, Nathalie; Siguret, Virginie; Gouin-Thibault, Isabelle

2011-06-01

Vitamin K antagonist tablets are often split to fractionate the dose by elderly patients. We performed a study in order to assess the divisibility of one dosage strength of score-lined warfarin and of score-lined fluindione. Due to a recent change in the pharmaceutical form of fluindione in order to improve the divisibility, the study was performed over 2 different periods (with the « old » and with the « new » pharmaceutical form). In each period, 10 patients mean aged 82 years, 10 relatives, 10 nurses, 10 medical doctors) were asked to split in half warfarin tablets (W2 1(st) period et W2 2(d) period) and fluindione tablets (F2 et F'2), and to split fluindione tablets into 4 fragments (F4 et F'4). The first end-point was the accuracy of splitting estimated by the difference between the real and the expected weight of fragmented tablets. The statistical analysis was performed using an ANOVA test with 2 variables, subject and drug. The difference between the 2 periods were analyzed using an ANOVA test with 2 variables, subject and period. Over the 2 periods, the differences between real and expected weight were of 4.65% for W2 1(st) phase, 9.48% for F2, 15.35% for F4, 5.56% for W2 2(d )period, 4.30% for F'2, and 6.98% for F'4. The quality of splitting was statistically poorer in the elderly patient group compared to other subjects. This study was not design to assess the clinical relevance (bleeding or thromboembolism) or the anticoagulation control of the variations in drug mass due to inappropriate splitting of tablets. However, split form of drugs should be prescribe with caution to elderly patients.

Unraveling the hydrodynamics of split root water uptake experiments using CT scanned root architectures and three dimensional flow simulations

PubMed Central

Koebernick, Nicolai; Huber, Katrin; Kerkhofs, Elien; Vanderborght, Jan; Javaux, Mathieu; Vereecken, Harry; Vetterlein, Doris

2015-01-01

Split root experiments have the potential to disentangle water transport in roots and soil, enabling the investigation of the water uptake pattern of a root system. Interpretation of the experimental data assumes that water flow between the split soil compartments does not occur. Another approach to investigate root water uptake is by numerical simulations combining soil and root water flow depending on the parameterization and description of the root system. Our aim is to demonstrate the synergisms that emerge from combining split root experiments with simulations. We show how growing root architectures derived from temporally repeated X-ray CT scanning can be implemented in numerical soil-plant models. Faba beans were grown with and without split layers and exposed to a single drought period during which plant and soil water status were measured. Root architectures were reconstructed from CT scans and used in the model R-SWMS (root-soil water movement and solute transport) to simulate water potentials in soil and roots in 3D as well as water uptake by growing roots in different depths. CT scans revealed that root development was considerably lower with split layers compared to without. This coincided with a reduction of transpiration, stomatal conductance and shoot growth. Simulated predawn water potentials were lower in the presence of split layers. Simulations showed that this was related to an increased resistance to vertical water flow in the soil by the split layers. Comparison between measured and simulated soil water potentials proved that the split layers were not perfectly isolating and that redistribution of water from the lower, wetter compartments to the drier upper compartments took place, thus water losses were not equal to the root water uptake from those compartments. Still, the layers increased the resistance to vertical flow which resulted in lower simulated collar water potentials that led to reduced stomatal conductance and growth. PMID:26074935

Influence of different gaps among the split targets with gradient potential to the discharge effects generated by hypervelocity impact

NASA Astrophysics Data System (ADS)

Tang, Enling; Zhao, Liangliang; Han, Yafei; Zhang, Qingming; Wang, Ruizhi; He, Liping; Liu, Shuhua

2018-04-01

Due to the actual situation of spacecraft surface' charging, such as convex corners, weld line, whalebone and a multiple-interfaces with different materials, all these are main factors leading to uneven charging of spacecraft surface, even creating gradient potential. If the charging spacecraft surface is impacted by debris or micrometeor, discharge effect induced by impacting will pose a serious threat to spacecraft in orbit. So realizing spacecraft charging surface with different potential differences and grasping discharge characteristics are a decisive importance at the different experimental conditions in laboratory. To simulate the spacecraft surface with a gradient potential in laboratory, spacecraft surface is split into different parts, which different gaps reserved in 2 adjacent surface is added resistance to create different potential surfaces, and the high potential surface as a impact target in the split targets. Charging circuit system realizing different gradient potential and discharge test system are built by ourselves, combining with two-stage light gas gun loading system, six sets of experiments have been performed about hypervelocity impact on 2A12 aluminum split targets with gradient potentials. In the experiments, gaps of 2A12 aluminum target are the same among different parts in every experiments, the gaps of the split targets are 2mm, 3mm, 5mm, 7mm and 10mm in the experiments, respectively. And the applied voltage is 300V in all the experiments and high-potential 2A12 aluminum plate as the impact target. The experiments have been performed at the impact velocity of about 3km/s and the incidence angles of 60o and 90o (between projectile flying trajectory and target plane), respectively. Voltage probe and current probes are used for acquiring discharge voltages and currents during the process of the impact. The experimental results showed that the discharge induced by impact plasma were generated among high and low-potential target by forming a plasma discharge channel. With the increasing of the gaps among the high and low-potential targets, the peak values of the discharge current decreased first then increased. When the gaps of split targets reached a certain value, the peak values of the discharge current decreased again. Meanwhile, the gaps among high and low-potential targets was 5mm, the peak value of the discharge current was the smallest. With the increasing of the gaps among the split targets, a primary discharge duration also increased. However, when the gaps among the split targets were greater than 5mm, increasing trend of discharge duration would slow down. When the gaps among the split targets were greater than 7mm, there was a secondary discharge phenomenon, and the physical explanations were given about the influence of different gaps among the split targets on the discharge effects created by hypervelocity impact.

Learning classification trees

NASA Technical Reports Server (NTRS)

Buntine, Wray

1991-01-01

Algorithms for learning classification trees have had successes in artificial intelligence and statistics over many years. How a tree learning algorithm can be derived from Bayesian decision theory is outlined. This introduces Bayesian techniques for splitting, smoothing, and tree averaging. The splitting rule turns out to be similar to Quinlan's information gain splitting rule, while smoothing and averaging replace pruning. Comparative experiments with reimplementations of a minimum encoding approach, Quinlan's C4 and Breiman et al. Cart show the full Bayesian algorithm is consistently as good, or more accurate than these other approaches though at a computational price.

Zeeman splitting of 6.7 GHz methanol masers. On the uncertainty of magnetic field strength determinations

NASA Astrophysics Data System (ADS)

Vlemmings, W. H. T.; Torres, R. M.; Dodson, R.

2011-05-01

Context. To properly determine the role of magnetic fields during massive star formation, a statistically significant sample of field measurements probing different densities and regions around massive protostars needs to be established. However, relating Zeeman splitting measurements to magnetic field strengths needs a carefully determined splitting coefficient. Aims: Polarization observations of, in particular, the very abundant 6.7 GHz methanol maser, indicate that these masers appear to be good probes of the large scale magnetic field around massive protostars at number densities up to nH2 ≈ 109 cm-3. We thus investigate the Zeeman splitting of the 6.7 GHz methanol maser transition. Methods: We have observed of a sample of 46 bright northern hemisphere maser sources with the Effelsberg 100-m telescope and an additional 34 bright southern masers with the Parkes 64-m telescope in an attempt to measure their Zeeman splitting. We also revisit the previous calculation of the methanol Zeeman splitting coefficients and show that these were severely overestimated making the determination of magnetic field strengths highly uncertain. Results: In total 44 of the northern masers were detected and significant splitting between the right- and left-circular polarization spectra is determined in >75% of the sources with a flux density >20 Jy beam-1. Assuming the splitting is due to a magnetic field according to the regular Zeeman effect, the average detected Zeeman splitting corrected for field geometry is ~0.6 m s-1. Using an estimate of the 6.7 GHz A-type methanol maser Zeeman splitting coefficient based on old laboratory measurements of 25 GHz E-type methanol transitions this corresponds to a magnetic field of ~120 mG in the methanol maser region. This is significantly higher than expected using the typically assumed relation between magnetic field and density (B∝ n_H_20.47) and potentially indicates the extrapolation of the available laboratory measurements is invalid. The stability of the right- and left-circular calibration of the Parkes observations was insufficient to determine the Zeeman splitting of the Southern sample. Spectra are presented for all sources in both samples. Conclusions: There is no strong indication that the measured splitting between right- and left-circular polarization is due to non-Zeeman effects, although this cannot be ruled out until the Zeeman coefficient is properly determined. However, although the 6.7 GHz methanol masers are still excellent magnetic field morphology probes through linear polarization observations, previous derivations of magnetic fields strength turn out to be highly uncertain. A solution to this problem will require new laboratory measurements of the methanol Landé-factors. Table 2 and Figs. 5-7 are only available in electronic form at http://www.aanda.org

Split-Half Administration of the 2015 School Crime Supplement to the National Crime Victimization Survey. Methodology Report. NCES 2017-004

ERIC Educational Resources Information Center

Lessne, Deborah; Cidade, Melissa

2016-01-01

This report outlines the development, methodology, and results of the split-half administration of the 2015 School Crime Supplement (SCS) to the National Crime Victimization Survey (NCVS). The National Crime Victimization Survey (NCVS) is sponsored by the U.S. Department of Justice, Bureau of Justice Statistics (BJS). The National Center for…

Sampling for mercury at subnanogram per litre concentrations for load estimation in rivers

USGS Publications Warehouse

Colman, J.A.; Breault, R.F.

2000-01-01

Estimation of constituent loads in streams requires collection of stream samples that are representative of constituent concentrations, that is, composites of isokinetic multiple verticals collected along a stream transect. An all-Teflon isokinetic sampler (DH-81) cleaned in 75??C, 4 N HCl was tested using blank, split, and replicate samples to assess systematic and random sample contamination by mercury species. Mean mercury concentrations in field-equipment blanks were low: 0.135 ng??L-1 for total mercury (??Hg) and 0.0086 ng??L-1 for monomethyl mercury (MeHg). Mean square errors (MSE) for ??Hg and MeHg duplicate samples collected at eight sampling stations were not statistically different from MSE of samples split in the laboratory, which represent the analytical and splitting error. Low fieldblank concentrations and statistically equal duplicate- and split-sample MSE values indicate that no measurable contamination was occurring during sampling. Standard deviations associated with example mercury load estimations were four to five times larger, on a relative basis, than standard deviations calculated from duplicate samples, indicating that error of the load determination was primarily a function of the loading model used, not of sampling or analytical methods.

The ground state tunneling splitting and the zero point energy of malonaldehyde: a quantum Monte Carlo determination.

PubMed

Viel, Alexandra; Coutinho-Neto, Maurício D; Manthe, Uwe

2007-01-14

Quantum dynamics calculations of the ground state tunneling splitting and of the zero point energy of malonaldehyde on the full dimensional potential energy surface proposed by Yagi et al. [J. Chem. Phys. 1154, 10647 (2001)] are reported. The exact diffusion Monte Carlo and the projection operator imaginary time spectral evolution methods are used to compute accurate benchmark results for this 21-dimensional ab initio potential energy surface. A tunneling splitting of 25.7+/-0.3 cm-1 is obtained, and the vibrational ground state energy is found to be 15 122+/-4 cm-1. Isotopic substitution of the tunneling hydrogen modifies the tunneling splitting down to 3.21+/-0.09 cm-1 and the vibrational ground state energy to 14 385+/-2 cm-1. The computed tunneling splittings are slightly higher than the experimental values as expected from the potential energy surface which slightly underestimates the barrier height, and they are slightly lower than the results from the instanton theory obtained using the same potential energy surface.

Quasi-QSAR for mutagenic potential of multi-walled carbon-nanotubes.

PubMed

Toropov, Andrey A; Toropova, Alla P

2015-04-01

Available on the Internet, the CORAL software (http://www.insilico.eu/coral) has been used to build up quasi-quantitative structure-activity relationships (quasi-QSAR) for prediction of mutagenic potential of multi-walled carbon-nanotubes (MWCNTs). In contrast with the previous models built up by CORAL which were based on representation of the molecular structure by simplified molecular input-line entry system (SMILES) the quasi-QSARs based on the representation of conditions (not on the molecular structure) such as concentration, presence (absence) S9 mix, the using (or without the using) of preincubation were encoded by so-called quasi-SMILES. The statistical characteristics of these models (quasi-QSARs) for three random splits into the visible training set and test set and invisible validation set are the following: (i) split 1: n=13, r(2)=0.8037, q(2)=0.7260, s=0.033, F=45 (training set); n=5, r(2)=0.9102, s=0.071 (test set); n=6, r(2)=0.7627, s=0.044 (validation set); (ii) split 2: n=13, r(2)=0.6446, q(2)=0.4733, s=0.045, F=20 (training set); n=5, r(2)=0.6785, s=0.054 (test set); n=6, r(2)=0.9593, s=0.032 (validation set); and (iii) n=14, r(2)=0.8087, q(2)=0.6975, s=0.026, F=51 (training set); n=5, r(2)=0.9453, s=0.074 (test set); n=5, r(2)=0.8951, s=0.052 (validation set). Copyright © 2014 Elsevier Ltd. All rights reserved.

Bad splits in bilateral sagittal split osteotomy: systematic review and meta-analysis of reported risk factors.

PubMed

Steenen, S A; van Wijk, A J; Becking, A G

2016-08-01

An unfavourable and unanticipated pattern of the bilateral sagittal split osteotomy (BSSO) is generally referred to as a 'bad split'. Patient factors predictive of a bad split reported in the literature are controversial. Suggested risk factors are reviewed in this article. A systematic review was undertaken, yielding a total of 30 studies published between 1971 and 2015 reporting the incidence of bad split and patient age, and/or surgical technique employed, and/or the presence of third molars. These included 22 retrospective cohort studies, six prospective cohort studies, one matched-pair analysis, and one case series. Spearman's rank correlation showed a statistically significant but weak correlation between increasing average age and increasing occurrence of bad splits in 18 studies (ρ=0.229; P<0.01). No comparative studies were found that assessed the incidence of bad split among the different splitting techniques. A meta-analysis pooling the effect sizes of seven cohort studies showed no significant difference in the incidence of bad split between cohorts of patients with third molars present and concomitantly removed during surgery, and patients in whom third molars were removed at least 6 months preoperatively (odds ratio 1.16, 95% confidence interval 0.73-1.85, Z=0.64, P=0.52). In summary, there is no robust evidence to date to show that any risk factor influences the incidence of bad split. Copyright © 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Split-Half Administration of the 2015 School Crime Supplement to the National Crime Victimization Survey: Methodology Report. NCES 2017-004

ERIC Educational Resources Information Center

Lessne, Deborah; Cidade, Melissa

2016-01-01

This report outlines the development, methodology, and results of the split-half administration of the 2015 School Crime Supplement (SCS) to the National Crime Victimization Survey (NCVS). The National Crime Victimization Survey (NCVS) is sponsored by the U.S. Department of Justice, Bureau of Justice Statistics (BJS). The U.S. Census Bureau…

Visual Acuity Improvement in Continuous vs Divided Occlusion in Anisometropic Amblyopia

PubMed Central

Irfani, Irawati; Feriyanto, Feri; Oktarima, Primawita; Kartasasmita, Arief

2018-01-01

Purpose: To compare visual acuity improvement between continuous and split part-time occlusion for the treatment of moderate and severe anisometropic amblyopia. Methods: Randomised clinical trials in 6 – 13 y.o children with moderate and severe anisometropic amblyopia. Each patient was consecutively selected with continuous or split part-time occlusion. Best corrected visual acuity’s improvement was followed up to six weeks and statistical data were analyzed using chi square and unpaired t-test. Results: Best corrected visual acuity’s improvement was comparable between continuous and split part-time occlusion (0.20±0.27 vs 0.21±0.25; p = 0.79). Conclusion: Split part-time occlusion may be considered as an alternative treatment for moderate and severe anisometropic amblyopia treatment. PMID:29515681

Full-dimensional quantum calculations of ground-state tunneling splitting of malonaldehyde using an accurate ab initio potential energy surface

NASA Astrophysics Data System (ADS)

Wang, Yimin; Braams, Bastiaan J.; Bowman, Joel M.; Carter, Stuart; Tew, David P.

2008-06-01

Quantum calculations of the ground vibrational state tunneling splitting of H-atom and D-atom transfer in malonaldehyde are performed on a full-dimensional ab initio potential energy surface (PES). The PES is a fit to 11 147 near basis-set-limit frozen-core CCSD(T) electronic energies. This surface properly describes the invariance of the potential with respect to all permutations of identical atoms. The saddle-point barrier for the H-atom transfer on the PES is 4.1 kcal/mol, in excellent agreement with the reported ab initio value. Model one-dimensional and ``exact'' full-dimensional calculations of the splitting for H- and D-atom transfer are done using this PES. The tunneling splittings in full dimensionality are calculated using the unbiased ``fixed-node'' diffusion Monte Carlo (DMC) method in Cartesian and saddle-point normal coordinates. The ground-state tunneling splitting is found to be 21.6 cm-1 in Cartesian coordinates and 22.6 cm-1 in normal coordinates, with an uncertainty of 2-3 cm-1. This splitting is also calculated based on a model which makes use of the exact single-well zero-point energy (ZPE) obtained with the MULTIMODE code and DMC ZPE and this calculation gives a tunneling splitting of 21-22 cm-1. The corresponding computed splittings for the D-atom transfer are 3.0, 3.1, and 2-3 cm-1. These calculated tunneling splittings agree with each other to within less than the standard uncertainties obtained with the DMC method used, which are between 2 and 3 cm-1, and agree well with the experimental values of 21.6 and 2.9 cm-1 for the H and D transfer, respectively.

Full-dimensional quantum calculations of ground-state tunneling splitting of malonaldehyde using an accurate ab initio potential energy surface.

PubMed

Wang, Yimin; Braams, Bastiaan J; Bowman, Joel M; Carter, Stuart; Tew, David P

2008-06-14

Quantum calculations of the ground vibrational state tunneling splitting of H-atom and D-atom transfer in malonaldehyde are performed on a full-dimensional ab initio potential energy surface (PES). The PES is a fit to 11 147 near basis-set-limit frozen-core CCSD(T) electronic energies. This surface properly describes the invariance of the potential with respect to all permutations of identical atoms. The saddle-point barrier for the H-atom transfer on the PES is 4.1 kcalmol, in excellent agreement with the reported ab initio value. Model one-dimensional and "exact" full-dimensional calculations of the splitting for H- and D-atom transfer are done using this PES. The tunneling splittings in full dimensionality are calculated using the unbiased "fixed-node" diffusion Monte Carlo (DMC) method in Cartesian and saddle-point normal coordinates. The ground-state tunneling splitting is found to be 21.6 cm(-1) in Cartesian coordinates and 22.6 cm(-1) in normal coordinates, with an uncertainty of 2-3 cm(-1). This splitting is also calculated based on a model which makes use of the exact single-well zero-point energy (ZPE) obtained with the MULTIMODE code and DMC ZPE and this calculation gives a tunneling splitting of 21-22 cm(-1). The corresponding computed splittings for the D-atom transfer are 3.0, 3.1, and 2-3 cm(-1). These calculated tunneling splittings agree with each other to within less than the standard uncertainties obtained with the DMC method used, which are between 2 and 3 cm(-1), and agree well with the experimental values of 21.6 and 2.9 cm(-1) for the H and D transfer, respectively.

Triadic split-merge sampler

NASA Astrophysics Data System (ADS)

van Rossum, Anne C.; Lin, Hai Xiang; Dubbeldam, Johan; van der Herik, H. Jaap

2018-04-01

In machine vision typical heuristic methods to extract parameterized objects out of raw data points are the Hough transform and RANSAC. Bayesian models carry the promise to optimally extract such parameterized objects given a correct definition of the model and the type of noise at hand. A category of solvers for Bayesian models are Markov chain Monte Carlo methods. Naive implementations of MCMC methods suffer from slow convergence in machine vision due to the complexity of the parameter space. Towards this blocked Gibbs and split-merge samplers have been developed that assign multiple data points to clusters at once. In this paper we introduce a new split-merge sampler, the triadic split-merge sampler, that perform steps between two and three randomly chosen clusters. This has two advantages. First, it reduces the asymmetry between the split and merge steps. Second, it is able to propose a new cluster that is composed out of data points from two different clusters. Both advantages speed up convergence which we demonstrate on a line extraction problem. We show that the triadic split-merge sampler outperforms the conventional split-merge sampler. Although this new MCMC sampler is demonstrated in this machine vision context, its application extend to the very general domain of statistical inference.

On Lack of Robustness in Hydrological Model Development Due to Absence of Guidelines for Selecting Calibration and Evaluation Data: Demonstration for Data-Driven Models

NASA Astrophysics Data System (ADS)

Zheng, Feifei; Maier, Holger R.; Wu, Wenyan; Dandy, Graeme C.; Gupta, Hoshin V.; Zhang, Tuqiao

2018-02-01

Hydrological models are used for a wide variety of engineering purposes, including streamflow forecasting and flood-risk estimation. To develop such models, it is common to allocate the available data to calibration and evaluation data subsets. Surprisingly, the issue of how this allocation can affect model evaluation performance has been largely ignored in the research literature. This paper discusses the evaluation performance bias that can arise from how available data are allocated to calibration and evaluation subsets. As a first step to assessing this issue in a statistically rigorous fashion, we present a comprehensive investigation of the influence of data allocation on the development of data-driven artificial neural network (ANN) models of streamflow. Four well-known formal data splitting methods are applied to 754 catchments from Australia and the U.S. to develop 902,483 ANN models. Results clearly show that the choice of the method used for data allocation has a significant impact on model performance, particularly for runoff data that are more highly skewed, highlighting the importance of considering the impact of data splitting when developing hydrological models. The statistical behavior of the data splitting methods investigated is discussed and guidance is offered on the selection of the most appropriate data splitting methods to achieve representative evaluation performance for streamflow data with different statistical properties. Although our results are obtained for data-driven models, they highlight the fact that this issue is likely to have a significant impact on all types of hydrological models, especially conceptual rainfall-runoff models.

Ab initio determination of mode coupling in HSSH - The torsional splitting in the first excited S-S stretching state

NASA Technical Reports Server (NTRS)

Herbst, Eric; Winnewisser, G.; Yamada, K. M. T.; Defrees, D. J.; Mclean, A. D.

1989-01-01

A mechanism for the enhanced splitting detected in the millimeter-wave rotational spectra of the first excited S-S stretching state of HSSH (disulfane) has been studied. The mechanism, which involves a potential coupling between the first excited S-S stretching state and excited torsional states, has been investigated in part by the use of ab initio theory. Based on an ab initio potential surface, coupling matrix elements have been calculated, and the amount of splitting has then been estimated by second-order perturbation theory. The result, while not in quantitative agreement with the measured splitting, lends plausibility to the assumed mechanism.

US Geological Survey nutrient preservation experiment : experimental design, statistical analysis, and interpretation of analytical results

USGS Publications Warehouse

Patton, Charles J.; Gilroy, Edward J.

1999-01-01

Data on which this report is based, including nutrient concentrations in synthetic reference samples determined concurrently with those in real samples, are extensive (greater than 20,000 determinations) and have been published separately. In addition to confirming the well-documented instability of nitrite in acidified samples, this study also demonstrates that when biota are removed from samples at collection sites by 0.45-micrometer membrane filtration, subsequent preservation with sulfuric acid or mercury (II) provides no statistically significant improvement in nutrient concentration stability during storage at 4 degrees Celsius for 30 days. Biocide preservation had no statistically significant effect on the 30-day stability of phosphorus concentrations in whole-water splits from any of the 15 stations, but did stabilize Kjeldahl nitrogen concentrations in whole-water splits from three data-collection stations where ammonium accounted for at least half of the measured Kjeldahl nitrogen.

Split-plot microarray experiments: issues of design, power and sample size.

PubMed

Tsai, Pi-Wen; Lee, Mei-Ling Ting

2005-01-01

This article focuses on microarray experiments with two or more factors in which treatment combinations of the factors corresponding to the samples paired together onto arrays are not completely random. A main effect of one (or more) factor(s) is confounded with arrays (the experimental blocks). This is called a split-plot microarray experiment. We utilise an analysis of variance (ANOVA) model to assess differentially expressed genes for between-array and within-array comparisons that are generic under a split-plot microarray experiment. Instead of standard t- or F-test statistics that rely on mean square errors of the ANOVA model, we use a robust method, referred to as 'a pooled percentile estimator', to identify genes that are differentially expressed across different treatment conditions. We illustrate the design and analysis of split-plot microarray experiments based on a case application described by Jin et al. A brief discussion of power and sample size for split-plot microarray experiments is also presented.

Parallel object-oriented decision tree system

DOEpatents

Kamath,; Chandrika, Cantu-Paz [Dublin, CA; Erick, [Oakland, CA

2006-02-28

A data mining decision tree system that uncovers patterns, associations, anomalies, and other statistically significant structures in data by reading and displaying data files, extracting relevant features for each of the objects, and using a method of recognizing patterns among the objects based upon object features through a decision tree that reads the data, sorts the data if necessary, determines the best manner to split the data into subsets according to some criterion, and splits the data.

Evaluation of Mandibular Anatomy Associated With Bad Splits in Sagittal Split Ramus Osteotomy of Mandible.

PubMed

Wang, Tongyue; Han, Jeong Joon; Oh, Hee-Kyun; Park, Hong-Ju; Jung, Seunggon; Park, Yeong-Joon; Kook, Min-Suk

2016-07-01

This study aimed to identify risk factors associated with bad splits during sagittal split ramus osteotomy by using three-dimensional computed tomography. This study included 8 bad splits and 47 normal patients without bad splits. Mandibular anatomic parameters related to osteotomy line were measured. These included anteroposterior width of the ramus at level of lingula, distance between external oblique ridge and lingula, distance between sigmoid notch and inferior border of mandible, mandibular angle, distance between inferior outer surface of mandibular canal and inferior border of mandible under distal root of second molar (MCEM), buccolingual thickness of the ramus at level of lingula, and buccolingual thickness of the area just distal to first molar (BTM1) and second molar (BTM2). The incidence of bad splits in 625 sagittal split osteotomies was 1.28%. Compared with normal group, bad split group exhibited significantly thinner BTM2 and shorter sigmoid notch and inferior border of mandible (P <0.05). However, for BTM1 and buccolingual thickness of the ramus at level of lingula, there was no statistical difference between the 2 groups. Mandibular angle, anteroposterior width of the ramus at level of lingula, external oblique ridge and lingula, and MCEM were not significantly different between the groups. This study suggests that patients with shorter ramus and low thickness of the buccolingual alveolar region distal to the second molar had a higher risk of bad splits. These anatomic data may help surgeons to choose the safest surgical techniques and best osteotomy sites.

A statistical study of ion pitch-angle distributions

NASA Technical Reports Server (NTRS)

Sibeck, D. G.; Mcentire, R. W.; Lui, A. T. Y.; Krimigis, S. M.

1987-01-01

Preliminary results of a statistical study of energetic (34-50 keV) ion pitch-angle distributions (PADs) within 9 Re of earth provide evidence for an orderly pattern consistent with both drift-shell splitting and magnetopause shadowing. Normal ion PADs dominate the dayside and inner magnetosphere. Butterfly PADs typically occur in a narrow belt stretching from dusk to dawn through midnight, where they approach within 6 Re of earth. While those ion butterfly PADs that typically occur on closed drift paths are mainly caused by drift-shell splitting, there is also evidence for magnetopause shadowing in observations of more frequent butterfly PAD occurrence in the outer magnetosphere near dawn than dusk. Isotropic and gradient boundary PADs terminate the tailward extent of the butterfly ion PAD belt.

Dependence of the 0.7 anomaly on the curvature of the potential barrier in quantum wires

NASA Astrophysics Data System (ADS)

Smith, L. W.; Al-Taie, H.; Lesage, A. A. J.; Sfigakis, F.; See, P.; Griffiths, J. P.; Beere, H. E.; Jones, G. A. C.; Ritchie, D. A.; Hamilton, A. R.; Kelly, M. J.; Smith, C. G.

2015-06-01

Ninety-eight one-dimensional channels defined using split gates fabricated on a GaAs/AlGaAs heterostructure are measured during one cooldown at 1.4 K. The devices are arranged in an array on a single chip and are individually addressed using a multiplexing technique. The anomalous conductance feature known as the "0.7 structure" is studied using statistical techniques. The ensemble of data shows that the 0.7 anomaly becomes more pronounced and occurs at lower values as the curvature of the potential barrier in the transport direction decreases. This corresponds to an increase in the effective length of the device. The 0.7 anomaly is not strongly influenced by other properties of the conductance related to density. The curvature of the potential barrier appears to be the primary factor governing the shape of the 0.7 structure at a given T and B .

Potential of human twin embryos generated by embryo splitting in assisted reproduction and research.

PubMed

Noli, Laila; Ogilvie, Caroline; Khalaf, Yacoub; Ilic, Dusko

2017-03-01

Embryo splitting or twinning has been widely used in veterinary medicine over 20 years to generate monozygotic twins with desirable genetic characteristics. The first human embryo splitting, reported in 1993, triggered fierce ethical debate on human embryo cloning. Since Dolly the sheep was born in 1997, the international community has acknowledged the complexity of the moral arguments related to this research and has expressed concerns about the potential for reproductive cloning in humans. A number of countries have formulated bans either through laws, decrees or official statements. However, in general, these laws specifically define cloning as an embryo that is generated via nuclear transfer (NT) and do not mention embryo splitting. Only the UK includes under cloning both embryo splitting and NT in the same legislation. On the contrary, the Ethics Committee of the American Society for Reproductive Medicine does not have a major ethical objection to transferring two or more artificially created embryos with the same genome with the aim of producing a single pregnancy, stating that 'since embryo splitting has the potential to improve the efficacy of IVF treatments for infertility, research to investigate the technique is ethically acceptable'. Embryo splitting has been introduced successfully to the veterinary medicine several decades ago and today is a part of standard practice. We present here an overview of embryo splitting experiments in humans and non-human primates and discuss the potential of this technology in assisted reproduction and research. A comprehensive literature search was carried out using PUBMED and Google Scholar databases to identify studies on embryo splitting in humans and non-human primates. 'Embryo splitting' and 'embryo twinning' were used as the keywords, alone or in combination with other search phrases relevant to the topics of biology of preimplantation embryos. A very limited number of studies have been conducted in humans and non-human primates. The published material, especially the studies with human embryos, is controversial. Some reports suggest that twinning technology will find clinical use in reproductive medicine in the future, whereas others conclude the opposite that human twin embryos created in vitro are unsuitable not only for clinical, but also for research, purposes. The blastomere biopsy technique of embryo splitting seems to be unsuitable for either clinical or research purposes; however, embryo bisection, a preferable method of cloning in veterinary medicine, has not yet been tested on human embryos. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Rouleaux red blood cells splitting in microscopic thin blood smear images via local maxima, circles drawing, and mapping with original RBCs.

PubMed

Rehman, Amjad; Abbas, Naveed; Saba, Tanzila; Mahmood, Toqeer; Kolivand, Hoshang

2018-04-10

Splitting the rouleaux RBCs from single RBCs and its further subdivision is a challenging area in computer-assisted diagnosis of blood. This phenomenon is applied in complete blood count, anemia, leukemia, and malaria tests. Several automated techniques are reported in the state of art for this task but face either under or over splitting problems. The current research presents a novel approach to split Rouleaux red blood cells (chains of RBCs) precisely, which are frequently observed in the thin blood smear images. Accordingly, this research address the rouleaux splitting problem in a realistic, efficient and automated way by considering the distance transform and local maxima of the rouleaux RBCs. Rouleaux RBCs are splitted by taking their local maxima as the centres to draw circles by mid-point circle algorithm. The resulting circles are further mapped with single RBC in Rouleaux to preserve its original shape. The results of the proposed approach on standard data set are presented and analyzed statistically by achieving an average recall of 0.059, an average precision of 0.067 and F-measure 0.063 are achieved through ground truth with visual inspection. © 2018 Wiley Periodicals, Inc.

On the tunneling splitting in a cyclic water trimer

NASA Astrophysics Data System (ADS)

Mandziuk, Margaret

2016-09-01

We propose an alternative explanation of the "bifurcation" splittings observed for the water trimer in the VRT experiments of Saykally's group [Chem. Rev. 103 (2003) 2533]. In our interpretation, the splittings originate from the quantum delocalization of hydrogen bonded protons in the mean field potential between two oxygen neighbors. The pattern and the order of our calculated splittings is in the range of experimentally observed values. Consequently, quantum delocalization of protons should be considered seriously as the origin of experimentally observed fine splittings. The presented model can be extended to a water pentamer and, hopefully, advance our understanding of liquid water.

Gender and academic medicine: a good pipeline of women graduates is not advancing.

PubMed

Puljak, Livia; Kojundzic, Sanja Lovric; Sapunar, Damir

2008-01-01

Women are underrepresented in the higher levels of appointment in academic medicine, despite the so-called feminization of medicine. A 27-year (1979-2006) retrospective study was conducted regarding the success and advancement of women and men at the University of Split School of Medicine in Croatia. Data were collected from the school's archive, including number of women and men among applicants, enrollees, graduates, teachers, department chairs and the school management: high school grade averages and admission tests scores by applicant gender and gender-based graduation grade averages. The number and gender patterns of all employed and unemployed physicians in the Split-Dalmatia county were also collected. Men represent the minority among applicants, enrollees, and graduates, whereas women were in the minority among faculty, department chairs, and the school management across all 27 years. Graduation grades from high school and medical school showed that women were statistically better students, although the difference was slight. In the same geographic area, women are more often unemployed and less likely to specialize. More women are applying, enrolling and graduating from the University of Split School of Medicine. Women also perform statistically better on entrance exam and have better graduation grades, yet they remain a minority in faculty and leadership positions. A review of county-wise employment statistics revealed that women were more frequently unemployed and less likely to specialize in this study.

The Interaction of Fatigue and Potentiation Following an Acute Bout of Unilateral Squats

PubMed Central

Andrews, Samantha K.; Horodyski, Jesse M.; MacLeod, Daniel A.; Whitten, Joseph; Behm, David G.

2016-01-01

A prior conditioning resistance exercise can augment subsequent performance of the affected muscles due to the effects of post-activation potentiation (PAP). The non-local muscle fatigue literature has illustrated the global neural effects of unilateral fatigue. However, no studies have examined the possibility of acute non-local performance enhancements. The objective of the study was to provide a conditioning stimulus in an attempt to potentiate the subsequent jump performance of the affected limb and determine if there were performance changes in the contralateral limb. Using a randomized allocation, 14 subjects (6 females, 8 males) completed three conditions on separate days: 1) unilateral, dominant leg, Bulgarian split squat protocol with testing of the exercised leg, 2) unilateral, dominant leg, Bulgarian split squat protocol with testing of the contralateral, non-exercised leg and 3) control session with testing of the non-dominant leg. Pre- and post-testing consisted of countermovement (CMJ) and drop jumps (DJ). The exercised leg exhibited CMJ height increases of 3.5% (p = 0.008; d = 0.28), 4.0% (p = 0.011; d = 0.33) and 3.2% (p = 0.013; d = 0.26) at 1, 5, and 10 min post-intervention respectively. The contralateral CMJ height had 2.0% (p = 0.034; d = 0.18), 1.2% (p = 0.2; d = 0.12), and 2.1% (p = 0.05; d = 0.17) deficits at 1, 5, and 10 min post-intervention respectively. Similar relative results were found for CMJ power. There were no significant interactions for DJ measures or control CMJ measures. The findings suggest that PAP effects were likely predominant for the exercised leg whereas the conditioning exercise provided trivial magnitude although statistically significant neural impairments for the contralateral limb. Key points Post-activation potentiation of unilateral CMJ height was achieved following 5 sequential squats at 50% 1RM, 2 squats at 70% 1RM, 1 squat at 90% 1RM with 3 min rest periods. The conditioning exercises did not elicit significant drop jump improvements, likely due to balance challenges. In contrast to the potentiation of the affected leg, there were statistically significant impairments of contralateral CMJ height suggesting the co-existence of post-activation potentiation (affected limb) and crossover neural fatigue. PMID:27928208

Evaluation of the Transverse Displacement of the Proximal Segment After Bilateral Sagittal Split Ramus Osteotomy With Different Lingual Split Patterns and Advancement Amounts Using the Finite Element Method.

PubMed

Dai, Zhi; Hou, Min; Ma, Wen; Song, Da-Li; Zhang, Chun-Xiang; Zhou, Wei-Yuan

2016-11-01

To evaluate transverse displacement of the proximal segment after bilateral sagittal split ramus osteotomy (BSSO) advancement with different lingual split patterns and advancement amounts and to determine the influential factors related to mandibular width. A 3-dimensional finite element model of the mandible including the temporomandibular joint was created for a presurgical simulation and for BSSO with lingual split patterns I (T1; Hunsuck split) and II (T2; Obwegeser split). The mandible was advanced 3 mm (A3) and 8 mm (A8) and fixated with a conventional titanium plate. Ansys software was used to measure the linear distances of the interproximal segments and to analyze the transverse displacement distribution of proximal segments after applying the load of masticatory muscle force groups. After surgical simulation, T1A3, T1A8, T2A3, and T2A8 showed increased transverse widths (mean, 2.99, 4.70, 2.36, and 4.42 mm, respectively). For transverse augmentation, there was a statistically significant difference between the 2 different mandibular advancement amounts in T1 and in T2 (P ≤ .000), but no significant differences was observed between T1 and T2 (P ≥ .058). The maximum transverse displacement distribution in the proximal segment was measured around the gonial area, and the early contact area was found near the border between the horizontal and sagittal osteotomy lines. Transverse displacements of proximal segments occur after BSSO advancement with T1 and T2 and transverse augmentation has statistically meaningful effects depending on the amount of advancement; however, no differences in transverse augmentation between T1 and T2 were identified. The fulcrum caused by the early contact between the proximal and distal segments could be an influential factor related to mandibular width. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Adverse drug reactions and outcome of short course anti-tuberculosis drugs between single daily dose and split drug dose (BID) in pulmonary tuberculosis.

PubMed

Chuchottaworn, Charoen; Saipan, Benjawan; Kittisup, Chomnapa; Cheewakul, Krisana

2012-08-01

Standard six months short course regimen for treatment of pulmonary tuberculosis is very effective and is recommended as standard treatment. But this regimen composes of many drugs and causes high adverse drug reactions especially gastrointestinal irritation. Spitted administration of drugs to two times a day may reduce adverse drug reactions. To study adverse drug reactions and outcome of single daily versus split drug (two times a day) administration of standard six month short course regimen in newly diagnosed pulmonary tuberculosis. Newly diagnosed pulmonary tuberculosis patients of the Central Chest Institute of Thailand were randomized to receive standard six months regimen once daily or two times a day (split drug). Patients were followed-up every two weeks and a questionnaire was used to detect adverse drug reactions. Outcome of treatment was evaluated according to national tuberculosis treatment guideline. 122 pulmonary tuberculosis were eligible for the present study and 61 patients were enrolled to each group of once daily or split drug regimen. Pulmonary tuberculosis patients who received split drug regimen had a higher cure rate but not statistical significance because of lower transfer out rate. Adverse drug reactions were similar in both groups of patients who received once daily and split drug regimen. Although split drug group had lower gastrointestinal adverse drug reactions. Split drug regimen has the same cure rate of treatment as single daily regimen and same adverse drug reactions.

Reliability and Repeatability of Cone Density Measurements in Patients With Stargardt Disease and RPGR-Associated Retinopathy.

PubMed

Tanna, Preena; Kasilian, Melissa; Strauss, Rupert; Tee, James; Kalitzeos, Angelos; Tarima, Sergey; Visotcky, Alexis; Dubra, Alfredo; Carroll, Joseph; Michaelides, Michel

2017-07-01

To assess reliability and repeatability of cone density measurements by using confocal and (nonconfocal) split-detector adaptive optics scanning light ophthalmoscopy (AOSLO) imaging. It will be determined whether cone density values are significantly different between modalities in Stargardt disease (STGD) and retinitis pigmentosa GTPase regulator (RPGR)-associated retinopathy. Twelve patients with STGD (aged 9-52 years) and eight with RPGR-associated retinopathy (aged 11-31 years) were imaged using both confocal and split-detector AOSLO simultaneously. Four graders manually identified cone locations in each image that were used to calculate local densities. Each imaging modality was evaluated independently. The data set consisted of 1584 assessments of 99 STGD images (each image in two modalities and four graders who graded each image twice) and 928 RPGR assessments of 58 images (each image in two modalities and four graders who graded each image twice). For STGD assessments the reliability for confocal and split-detector AOSLO was 67.9% and 95.9%, respectively, and the repeatability was 71.2% and 97.3%, respectively. The differences in the measured cone density values between modalities were statistically significant for one grader. For RPGR assessments the reliability for confocal and split-detector AOSLO was 22.1% and 88.5%, respectively, and repeatability was 63.2% and 94.5%, respectively. The differences in cone density between modalities were statistically significant for all graders. Split-detector AOSLO greatly improved the reliability and repeatability of cone density measurements in both disorders and will be valuable for natural history studies and clinical trials using AOSLO. However, it appears that these indices may be disease dependent, implying the need for similar investigations in other conditions.

Reliability and Repeatability of Cone Density Measurements in Patients With Stargardt Disease and RPGR-Associated Retinopathy

PubMed Central

Tanna, Preena; Kasilian, Melissa; Strauss, Rupert; Tee, James; Kalitzeos, Angelos; Tarima, Sergey; Visotcky, Alexis; Dubra, Alfredo; Carroll, Joseph; Michaelides, Michel

2017-01-01

Purpose To assess reliability and repeatability of cone density measurements by using confocal and (nonconfocal) split-detector adaptive optics scanning light ophthalmoscopy (AOSLO) imaging. It will be determined whether cone density values are significantly different between modalities in Stargardt disease (STGD) and retinitis pigmentosa GTPase regulator (RPGR)–associated retinopathy. Methods Twelve patients with STGD (aged 9–52 years) and eight with RPGR-associated retinopathy (aged 11–31 years) were imaged using both confocal and split-detector AOSLO simultaneously. Four graders manually identified cone locations in each image that were used to calculate local densities. Each imaging modality was evaluated independently. The data set consisted of 1584 assessments of 99 STGD images (each image in two modalities and four graders who graded each image twice) and 928 RPGR assessments of 58 images (each image in two modalities and four graders who graded each image twice). Results For STGD assessments the reliability for confocal and split-detector AOSLO was 67.9% and 95.9%, respectively, and the repeatability was 71.2% and 97.3%, respectively. The differences in the measured cone density values between modalities were statistically significant for one grader. For RPGR assessments the reliability for confocal and split-detector AOSLO was 22.1% and 88.5%, respectively, and repeatability was 63.2% and 94.5%, respectively. The differences in cone density between modalities were statistically significant for all graders. Conclusions Split-detector AOSLO greatly improved the reliability and repeatability of cone density measurements in both disorders and will be valuable for natural history studies and clinical trials using AOSLO. However, it appears that these indices may be disease dependent, implying the need for similar investigations in other conditions. PMID:28738413

Modeling for influenza vaccines and adjuvants profile for safety prediction system using gene expression profiling and statistical tools

PubMed Central

Sasaki, Eita; Momose, Haruka; Hiradate, Yuki; Furuhata, Keiko; Takai, Mamiko; Asanuma, Hideki; Ishii, Ken J.

2018-01-01

Historically, vaccine safety assessments have been conducted by animal testing (e.g., quality control tests and adjuvant development). However, classical evaluation methods do not provide sufficient information to make treatment decisions. We previously identified biomarker genes as novel safety markers. Here, we developed a practical safety assessment system used to evaluate the intramuscular, intraperitoneal, and nasal inoculation routes to provide robust and comprehensive safety data. Influenza vaccines were used as model vaccines. A toxicity reference vaccine (RE) and poly I:C-adjuvanted hemagglutinin split vaccine were used as toxicity controls, while a non-adjuvanted hemagglutinin split vaccine and AddaVax (squalene-based oil-in-water nano-emulsion with a formulation similar to MF59)-adjuvanted hemagglutinin split vaccine were used as safety controls. Body weight changes, number of white blood cells, and lung biomarker gene expression profiles were determined in mice. In addition, vaccines were inoculated into mice by three different administration routes. Logistic regression analyses were carried out to determine the expression changes of each biomarker. The results showed that the regression equations clearly classified each vaccine according to its toxic potential and inoculation amount by biomarker expression levels. Interestingly, lung biomarker expression was nearly equivalent for the various inoculation routes. The results of the present safety evaluation were confirmed by the approximation rate for the toxicity control. This method may contribute to toxicity evaluation such as quality control tests and adjuvant development. PMID:29408882

Efficient solar water-splitting using a nanocrystalline CoO photocatalyst

NASA Astrophysics Data System (ADS)

Liao, Longb; Zhang, Qiuhui; Su, Zhihua; Zhao, Zhongzheng; Wang, Yanan; Li, Yang; Lu, Xiaoxiang; Wei, Dongguang; Feng, Guoying; Yu, Qingkai; Cai, Xiaojun; Zhao, Jimin; Ren, Zhifeng; Fang, Hui; Robles-Hernandez, Francisco; Baldelli, Steven; Bao, Jiming

2014-01-01

The generation of hydrogen from water using sunlight could potentially form the basis of a clean and renewable source of energy. Various water-splitting methods have been investigated previously, but the use of photocatalysts to split water into stoichiometric amounts of H2 and O2 (overall water splitting) without the use of external bias or sacrificial reagents is of particular interest because of its simplicity and potential low cost of operation. However, despite progress in the past decade, semiconductor water-splitting photocatalysts (such as (Ga1-xZnx)(N1-xOx)) do not exhibit good activity beyond 440 nm (refs 1,2,9) and water-splitting devices that can harvest visible light typically have a low solar-to-hydrogen efficiency of around 0.1%. Here we show that cobalt(II) oxide (CoO) nanoparticles can carry out overall water splitting with a solar-to-hydrogen efficiency of around 5%. The photocatalysts were synthesized from non-active CoO micropowders using two distinct methods (femtosecond laser ablation and mechanical ball milling), and the CoO nanoparticles that result can decompose pure water under visible-light irradiation without any co-catalysts or sacrificial reagents. Using electrochemical impedance spectroscopy, we show that the high photocatalytic activity of the nanoparticles arises from a significant shift in the position of the band edge of the material.

Communication: Tunnelling splitting in the phosphine molecule

NASA Astrophysics Data System (ADS)

Sousa-Silva, Clara; Tennyson, Jonathan; Yurchenko, Sergey N.

2016-09-01

Splitting due to tunnelling via the potential energy barrier has played a significant role in the study of molecular spectra since the early days of spectroscopy. The observation of the ammonia doublet led to attempts to find a phosphine analogous, but these have so far failed due to its considerably higher barrier. Full dimensional, variational nuclear motion calculations are used to predict splittings as a function of excitation energy. Simulated spectra suggest that such splittings should be observable in the near infrared via overtones of the ν2 bending mode starting with 4ν2.

Splitting of IVP bovine blastocyst affects morphology and gene expression of resulting demi-embryos during in vitro culture and in vivo elongation.

PubMed

Velasquez, Alejandra E; Castro, Fidel O; Veraguas, Daniel; Cox, Jose F; Lara, Evelyn; Briones, Mario; Rodriguez-Alvarez, Lleretny

2016-02-01

Embryo splitting might be used to increase offspring yield and for molecular analysis of embryo competence. How splitting affects developmental potential of embryos is unknown. This research aimed to study the effect of bovine blastocyst splitting on morphological and gene expression homogeneity of demi-embryos and on embryo competence during elongation. Grade I bovine blastocyst produced in vitro were split into halves and distributed in nine groups (3 × 3 setting according to age and stage before splitting; age: days 7-9; stage: early, expanded and hatched blastocysts). Homogeneity and survival rate in vitro after splitting (12 h, days 10 and 13) and the effect of splitting on embryo development at elongation after embryo transfer (day 17) were assessed morphologically and by RT-qPCR. The genes analysed were OCT4, SOX2, NANOG, CDX2, TP1, TKDP1, EOMES, and BAX. Approximately 90% of split embryos had a well conserved defined inner cell mass (ICM), 70% of the halves had similar size with no differences in gene expression 12 h after splitting. Split embryos cultured further conserved normal and comparable morphology at day 10 of development; this situation changes at day 13 when embryo morphology and gene expression differed markedly among demi-embryos. Split and non-split blastocysts were transferred to recipient cows and were recovered at day 17. Fifty per cent of non-split embryos were larger than 100 mm (33% for split embryos). OCT4, SOX2, TP1 and EOMES levels were down-regulated in elongated embryos derived from split blastocysts. In conclusion, splitting day-8 blastocysts yields homogenous demi-embryos in terms of developmental capability and gene expression, but the initiation of the filamentous stage seems to be affected by the splitting.

Vacuum Stability in Split SUSY and Little Higgs Models

NASA Astrophysics Data System (ADS)

Datta, Alakabha; Zhang, Xinmin

We study the stability of the effective Higgs potential in the split supersymmetry and Little Higgs models. In particular, we study the effects of higher dimensional operators in the effective potential on the Higgs mass predictions. We find that the size and sign of the higher dimensional operators can significantly change the Higgs mass required to maintain vacuum stability in Split SUSY models. In the Little Higgs models the effects of higher dimensional operators can be large because of a relatively lower cutoff scale. Working with a specific model we find that a contribution from the higher dimensional operator with coefficient of O(1) can destabilize the vacuum.

Dimensional Reduction for the General Markov Model on Phylogenetic Trees.

PubMed

Sumner, Jeremy G

2017-03-01

We present a method of dimensional reduction for the general Markov model of sequence evolution on a phylogenetic tree. We show that taking certain linear combinations of the associated random variables (site pattern counts) reduces the dimensionality of the model from exponential in the number of extant taxa, to quadratic in the number of taxa, while retaining the ability to statistically identify phylogenetic divergence events. A key feature is the identification of an invariant subspace which depends only bilinearly on the model parameters, in contrast to the usual multi-linear dependence in the full space. We discuss potential applications including the computation of split (edge) weights on phylogenetic trees from observed sequence data.

Mini-Split Heat Pumps Multifamily Retrofit Feasibility Study

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

Dentz, Jordan; Podorson, David; Varshney, Kapil

Mini-split heat pumps can provide space heating and cooling in many climates and are relatively affordable. These and other features make them potentially suitable for retrofitting into multifamily buildings in cold climates to replace electric resistance heating or other outmoded heating systems. This report investigates the suitability of mini-split heat pumps for multifamily retrofits. Various technical and regulatory barriers are discussed and modeling was performed to compare long-term costs of substituting mini-splits for a variety of other heating and cooling options. A number of utility programs have retrofit mini-splits in both single family and multifamily residences. Two such multifamily programsmore » are discussed in detail.« less

Replacing Resistance Heating with Mini-Split Heat Pumps, Sharon, Connecticut (Fact Sheet)

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

Not Available

Mini-split heat pumps can provide space heating and cooling in many climates and are relatively affordable. These and other features make them potentially suitable for retrofitting into multifamily buildings in cold climates to replace electric resistance heating or other outmoded heating systems. This report investigates the suitability of mini-split heat pumps for multifamily retrofits. Various technical and regulatory barriers are discussed and modeling was performed to compare long-term costs of substituting mini-splits for a variety of other heating and cooling options. A number of utility programs have retrofit mini-splits in both single family and multifamily residences. Two such multifamily programsmore » are discussed in detail.« less

Anisotropic in-plane spin splitting in an asymmetric (001) GaAs/AlGaAs quantum well

PubMed Central

2011-01-01

The in-plane spin splitting of conduction-band electron has been investigated in an asymmetric (001) GaAs/AlxGa1-xAs quantum well by time-resolved Kerr rotation technique under a transverse magnetic field. The distinctive anisotropy of the spin splitting was observed while the temperature is below approximately 200 K. This anisotropy emerges from the combined effect of Dresselhaus spin-orbit coupling plus asymmetric potential gradients. We also exploit the temperature dependence of spin-splitting energy. Both the anisotropy of spin splitting and the in-plane effective g-factor decrease with increasing temperature. PACS: 78.47.jm, 71.70.Ej, 75.75.+a, 72.25.Fe, PMID:21888636

Mini-Split Heat Pumps Multifamily Retrofit Feasibility Study

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

Dentz, J.; Podorson, D.; Varshney, K.

2014-05-01

Mini-split heat pumps can provide space heating and cooling in many climates and are relatively affordable. These and other features make them potentially suitable for retrofitting into multifamily buildings in cold climates to replace electric resistance heating or other outmoded heating systems. This report investigates the suitability of mini-split heat pumps for multifamily retrofits. Various technical and regulatory barriers are discussed and modeling was performed to compare long-term costs of substituting mini-splits for a variety of other heating and cooling options. A number of utility programs have retrofit mini-splits in both single family and multifamily residences. Two such multifamily programsmore » are discussed in detail.« less

Particulate photocatalysts for overall water splitting

NASA Astrophysics Data System (ADS)

Chen, Shanshan; Takata, Tsuyoshi; Domen, Kazunari

2017-10-01

The conversion of solar energy to chemical energy is a promising way of generating renewable energy. Hydrogen production by means of water splitting over semiconductor photocatalysts is a simple, cost-effective approach to large-scale solar hydrogen synthesis. Since the discovery of the Honda-Fujishima effect, considerable progress has been made in this field, and numerous photocatalytic materials and water-splitting systems have been developed. In this Review, we summarize existing water-splitting systems based on particulate photocatalysts, focusing on the main components: light-harvesting semiconductors and co-catalysts. The essential design principles of the materials employed for overall water-splitting systems based on one-step and two-step photoexcitation are also discussed, concentrating on three elementary processes: photoabsorption, charge transfer and surface catalytic reactions. Finally, we outline challenges and potential advances associated with solar water splitting by particulate photocatalysts for future commercial applications.

Temporal self-splitting of optical pulses

NASA Astrophysics Data System (ADS)

Ding, Chaoliang; Koivurova, Matias; Turunen, Jari; Pan, Liuzhan

2018-05-01

We present mathematical models for temporally and spectrally partially coherent pulse trains with Laguerre-Gaussian and Hermite-Gaussian Schell-model statistics as extensions of the standard Gaussian Schell model for pulse trains. We derive propagation formulas of both classes of pulsed fields in linearly dispersive media and in temporal optical systems. It is found that, in general, both types of fields exhibit time-domain self-splitting upon propagation. The Laguerre-Gaussian model leads to multiply peaked pulses, while the Hermite-Gaussian model leads to doubly peaked pulses, in the temporal far field (in dispersive media) or at the Fourier plane of a temporal system. In both model fields the character of the self-splitting phenomenon depends both on the degree of temporal and spectral coherence and on the power spectrum of the field.

Effect on signal-to-noise ratio of splitting the continuous contacts of cuff electrodes into smaller recording areas

PubMed Central

2013-01-01

Background Cuff electrodes have been widely used chronically in different clinical applications. This neural interface has been dominantly used for nerve stimulation while interfering noise is the major issue when employed for recording purposes. Advancements have been made in rejecting extra-neural interference by using continuous ring contacts in tripolar topologies. Ring contacts provide an average of the neural activity, and thus reduce the information retrieved. Splitting these contacts into smaller recording areas could potentially increase the information content. In this study, we investigate the impact of such discretization on the Signal-to-Noise Ratio (SNR). The effect of contacts positioning and an additional short circuited pair of electrodes were also addressed. Methods Different recording configurations using ring, dot, and a mixed of both contacts were studied in vitro in a frog model. An interfering signal was induced in the medium to simulate myoelectric noise. The experimental setup was design in such a way that the only difference between recordings was the configuration used. The inter-session experimental differences were taken care of by a common configuration that allowed normalization between electrode designs. Results It was found that splitting all contacts into small recording areas had negative effects on noise rejection. However, if this is only applied to the central contact creating a mixed tripole configuration, a considerable and statistically significant improvement was observed. Moreover, the signal to noise ratio was equal or larger than what can be achieved with the best known configuration, namely the short circuited tripole. This suggests that for recording purposes, any tripole topology would benefit from splitting the central contact into one or more discrete contacts. Conclusions Our results showed that a mixed tripole configuration performs better than the configuration including only ring contacts. Therefore, splitting the central ring contact of a cuff electrode into a number of dot contacts not only provides additional information but also an improved SNR. In addition, the effect of an additional pair of short circuited electrodes and the “end effect” observed with the presented method are in line with previous findings by other authors. PMID:23433089

Networks and the Epidemiology of Infectious Disease

PubMed Central

Danon, Leon; Ford, Ashley P.; House, Thomas; Jewell, Chris P.; Keeling, Matt J.; Roberts, Gareth O.; Ross, Joshua V.; Vernon, Matthew C.

2011-01-01

The science of networks has revolutionised research into the dynamics of interacting elements. It could be argued that epidemiology in particular has embraced the potential of network theory more than any other discipline. Here we review the growing body of research concerning the spread of infectious diseases on networks, focusing on the interplay between network theory and epidemiology. The review is split into four main sections, which examine: the types of network relevant to epidemiology; the multitude of ways these networks can be characterised; the statistical methods that can be applied to infer the epidemiological parameters on a realised network; and finally simulation and analytical methods to determine epidemic dynamics on a given network. Given the breadth of areas covered and the ever-expanding number of publications, a comprehensive review of all work is impossible. Instead, we provide a personalised overview into the areas of network epidemiology that have seen the greatest progress in recent years or have the greatest potential to provide novel insights. As such, considerable importance is placed on analytical approaches and statistical methods which are both rapidly expanding fields. Throughout this review we restrict our attention to epidemiological issues. PMID:21437001

Splitting Times of Doubly Quantized Vortices in Dilute Bose-Einstein Condensates

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

Huhtamaeki, J. A. M.; Pietilae, V.; Virtanen, S. M. M.

2006-09-15

Recently, the splitting of a topologically created doubly quantized vortex into two singly quantized vortices was experimentally investigated in dilute atomic cigar-shaped Bose-Einstein condensates [Y. Shin et al., Phys. Rev. Lett. 93, 160406 (2004)]. In particular, the dependency of the splitting time on the peak particle density was studied. We present results of theoretical simulations which closely mimic the experimental setup. We show that the combination of gravitational sag and time dependency of the trapping potential alone suffices to split the doubly quantized vortex in time scales which are in good agreement with the experiments.

Relationship between mandibular anatomy and the occurrence of a bad split upon sagittal split osteotomy.

PubMed

Aarabi, Mohammadali; Tabrizi, Reza; Hekmat, Mina; Shahidi, Shoaleh; Puzesh, Ayatollah

2014-12-01

A bad split is a troublesome complication of the sagittal split osteotomy (SSO). The aim of this study was to evaluate the relation between the occurrence of a bad split and mandibular anatomy in SSO using cone-beam computed tomography. The authors designed a cohort retrospective study. Forty-eight patients (96 SSO sites) were studied. The buccolingual thickness of the retromandibular area (BLR), the buccolingual thickness of the ramus at the level of the lingula (BLTR), the height of the mandible from the alveolar crest to the inferior border of the mandible, (ACIB), the distance between the sigmoid notch and the inferior border of the mandible (SIBM), and the anteroposterior width of the ramus (APWR) were measured. The independent t test was applied to compare anatomic measurements between the group with and the group without bad splits. The receiver operating characteristic (ROC) test was used to find a cutoff point in anatomic size for various parts of the mandible related to the occurrence of bad splits. The mean SIBM was 47.05±6.33 mm in group 1 (with bad splits) versus 40.66±2.44 mm in group 2 (without bad splits; P=.01). The mean BLTR was 5.74±1.11 mm in group 1 versus 3.19±0.55 mm in group 2 (P=.04). The mean BLR was 14.98±2.78 mm in group 1 versus 11.21±1.29 mm in group 2 (P=.001). No statistically significant difference was found for APWR and ACIB between the 2 groups. The ROC test showed cutoff points of 10.17 mm for BLR, 36.69 mm for SIBM, and 4.06 mm for BLTR. This study showed that certain mandibular anatomic differences can increase the risk of a bad split during SSO surgery. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Can computed tomography volumetry of the renal cortex replace MAG3-scintigraphy in all patients for determining split renal function?

PubMed

Houbois, Christian; Haneder, Stefan; Merkt, Martin; Morelli, John N; Schmidt, Matthias; Hellmich, Martin; Mueller, Roman-Ulrich; Wahba, Roger; Maintz, David; Puesken, Michael

2018-06-01

The current gold standard for determination of split renal function (SRF) is Tc-99m-mercapto-acetyltriglycin (MAG3) scintigraphy. Initial studies comparing MAG3-scintigraphy and CT-based renal cortex volumetry (RCV) for calculation of SRF have shown similar results in highly selected patient collectives with normal renal function (i.e. living kidney donors). This study aims to compare MAG3-scintigraphy and CT-RCV within a large unselected patient collective including patients with impaired renal function. For this assessment, 279 datasets (131 men, 148 women; mean age: 54.2 ± 12.9 years, range: 24-84 years) of patients who underwent MAG3-scintigraphy and contrast-enhanced abdominal CT within two weeks were retrospectively analyzed. Two independent readers assessed the CT-RCV in all CT datasets using a semi-automated volumetry tool. The MAG3-scintigraphy and CT-RCV methods were compared, stratified for the eGFR. Statistical analysis included descriptive statistics as well as inter- observer agreement. The absolute mean difference between the percentage contribution of the left and the right kidneys in total MAG3-clearance was 8.6%. Independent of eGFR, an overall sufficient agreement between both methods was established in all patients. A relatively small, tolerable systemic error resulted in an underestimation (max. 2%) of the left renal contribution to overall RCV. The results demonstrate that CT-RCV is a potential clinical replacement for MAG3-scintigraphy for calculation of SRF: CT-RCV demonstrates clinically tolerable differences with MAG3-scintigraphy, independent of patient eGFR. The relative complexity of the RCV method utilized is a potential limitation and may have contributed to the acceptable but only fair to moderate level of intra-reader reliability. Copyright © 2018 Elsevier B.V. All rights reserved.

Ring polymer dynamics in curved spaces

NASA Astrophysics Data System (ADS)

Wolf, S.; Curotto, E.

2012-07-01

We formulate an extension of the ring polymer dynamics approach to curved spaces using stereographic projection coordinates. We test the theory by simulating the particle in a ring, {T}^1, mapped by a stereographic projection using three potentials. Two of these are quadratic, and one is a nonconfining sinusoidal model. We propose a new class of algorithms for the integration of the ring polymer Hamilton equations in curved spaces. These are designed to improve the energy conservation of symplectic integrators based on the split operator approach. For manifolds, the position-position autocorrelation function can be formulated in numerous ways. We find that the position-position autocorrelation function computed from configurations in the Euclidean space {R}^2 that contains {T}^1 as a submanifold has the best statistical properties. The agreement with exact results obtained with vector space methods is excellent for all three potentials, for all values of time in the interval simulated, and for a relatively broad range of temperatures.

Recent Progress in Metal‐Organic Frameworks for Applications in Electrocatalytic and Photocatalytic Water Splitting

PubMed Central

Wang, Wei; Xu, Xiaomin; Zhou, Wei

2017-01-01

The development of clean and renewable energy materials as alternatives to fossil fuels is foreseen as a potential solution to the crucial problems of environmental pollution and energy shortages. Hydrogen is an ideal energy material for the future, and water splitting using solar/electrical energy is one way to generate hydrogen. Metal‐organic frameworks (MOFs) are a class of porous materials with unique properties that have received rapidly growing attention in recent years for applications in water splitting due to their remarkable design flexibility, ultra‐large surface‐to‐volume ratios and tunable pore channels. This review focuses on recent progress in the application of MOFs in electrocatalytic and photocatalytic water splitting for hydrogen generation, including both oxygen and hydrogen evolution. It starts with the fundamentals of electrocatalytic and photocatalytic water splitting and the related factors to determine the catalytic activity. The recent progress in the exploitation of MOFs for water splitting is then summarized, and strategies for designing MOF‐based catalysts for electrocatalytic and photocatalytic water splitting are presented. Finally, major challenges in the field of water splitting are highlighted, and some perspectives of MOF‐based catalysts for water splitting are proposed. PMID:28435777

A New Method of Assessing Uncertainty of the Cross-Convolution Method of Shear Wave Splitting Measurement

NASA Astrophysics Data System (ADS)

Schutt, D.; Breidt, J.; Corbalan Castejon, A.; Witt, D. R.

2017-12-01

Shear wave splitting is a commonly used and powerful method for constraining such phenomena as lithospheric strain history or asthenospheric flow. However, a number of challenges with the statistics of shear wave splitting have been noted. This creates difficulties in assessing whether two separate measurements are statistically similar or are indicating real differences in anisotropic structure, as well as for created proper station averaged sets of parameters for more complex situations such as multiple or dipping layers of anisotropy. We present a new method for calculating the most likely splitting parameters using the Menke and Levin [2003] method of cross-convolution. The Menke and Levin method is used because it can more readily be applied to a wider range of anisotropic scenarios than the commonly used Silver and Chan [1991] technique. In our approach, we derive a formula for the spectral density of a function of the microseismic noise and the impulse response of the correct anisotropic model that holds for the true anisotropic model parameters. This is compared to the spectral density of the observed signal convolved with the impulse response for an estimated set of anisotropic parameters. The most likely parameters are found when the former and latter spectral densities are the same. By using the Whittle likelihood to compare the two spectral densities, a likelihood grid for all possible anisotropic parameter values is generated. Using bootstrapping, the uncertainty and covariance between the various anisotropic parameters can be evaluated. We will show this works with a single layer of anisotropy and a vertically incident ray, and discuss the usefulness for a more complex case. The method shows great promise for calculating multiple layer anisotropy parameters with proper assessment of uncertainty. References: Menke, W., and Levin, V. 2003. The cross-convolution method for interpreting SKS splitting observations, with application to one and two-layer anisotropic earth models. Geophysical Journal International, 154: 379-392. doi:10.1046/j.1365-246X.2003.01937.x. Silver, P.G., and Chan, W.W. 1991. Shear Wave Splitting and Sub continental Mantle Deformation. Journal of Geophysical Research, 96: 429-454. doi:10.1029/91JB00899.

New Splitting Criteria for Decision Trees in Stationary Data Streams.

PubMed

Jaworski, Maciej; Duda, Piotr; Rutkowski, Leszek; Jaworski, Maciej; Duda, Piotr; Rutkowski, Leszek; Rutkowski, Leszek; Duda, Piotr; Jaworski, Maciej

2018-06-01

The most popular tools for stream data mining are based on decision trees. In previous 15 years, all designed methods, headed by the very fast decision tree algorithm, relayed on Hoeffding's inequality and hundreds of researchers followed this scheme. Recently, we have demonstrated that although the Hoeffding decision trees are an effective tool for dealing with stream data, they are a purely heuristic procedure; for example, classical decision trees such as ID3 or CART cannot be adopted to data stream mining using Hoeffding's inequality. Therefore, there is an urgent need to develop new algorithms, which are both mathematically justified and characterized by good performance. In this paper, we address this problem by developing a family of new splitting criteria for classification in stationary data streams and investigating their probabilistic properties. The new criteria, derived using appropriate statistical tools, are based on the misclassification error and the Gini index impurity measures. The general division of splitting criteria into two types is proposed. Attributes chosen based on type- splitting criteria guarantee, with high probability, the highest expected value of split measure. Type- criteria ensure that the chosen attribute is the same, with high probability, as it would be chosen based on the whole infinite data stream. Moreover, in this paper, two hybrid splitting criteria are proposed, which are the combinations of single criteria based on the misclassification error and Gini index.

Seven Pervasive Statistical Flaws in Cognitive Training Interventions

PubMed Central

Moreau, David; Kirk, Ian J.; Waldie, Karen E.

2016-01-01

The prospect of enhancing cognition is undoubtedly among the most exciting research questions currently bridging psychology, neuroscience, and evidence-based medicine. Yet, convincing claims in this line of work stem from designs that are prone to several shortcomings, thus threatening the credibility of training-induced cognitive enhancement. Here, we present seven pervasive statistical flaws in intervention designs: (i) lack of power; (ii) sampling error; (iii) continuous variable splits; (iv) erroneous interpretations of correlated gain scores; (v) single transfer assessments; (vi) multiple comparisons; and (vii) publication bias. Each flaw is illustrated with a Monte Carlo simulation to present its underlying mechanisms, gauge its magnitude, and discuss potential remedies. Although not restricted to training studies, these flaws are typically exacerbated in such designs, due to ubiquitous practices in data collection or data analysis. The article reviews these practices, so as to avoid common pitfalls when designing or analyzing an intervention. More generally, it is also intended as a reference for anyone interested in evaluating claims of cognitive enhancement. PMID:27148010

Urban Data Book : Volume 1. Urban Data - Atlanta-Miami

DOT National Transportation Integrated Search

1975-11-01

A quick reference compilation of certain population, socio-economic, employment, and modal split characteristics of the 35 largest Standard Metropolitan Statistical Areas (SMSA) in the United States is presented. The three basic groups or urban data ...

Factors that Affected Functional Outcome After a Delayed Excision and Split-Thickness Skin Graft on the Dorsal Side of Burned Hands.

PubMed

Shichinohe, Ryuji; Yamamoto, Yuhei; Kawashima, Kunihiro; Kimura, Chu; Ono, Kentaro; Horiuchi, Katsumi; Yoshida, Tetsunori; Murao, Naoki; Hayashi, Toshihiko; Funayama, Emi; Oyama, Akihiko; Furukawa, Hiroshi

Early excision and skin grafting is the principle treatment for a burned hand although there are occasions when it cannot be done such as severe general condition, delayed consultation, and the lack of a definitive assessment of burn depth. This study analyzes the factors that affected function after a delayed excision and skin graft for hands with a deep dermal burn. This study retrospectively evaluated 43 burned hands that required a delayed excision and split-thickness skin graft on the dorsal side. Cases were required to only have split-thickness skin grafting from the dorsum of the hand and fingers distally to at least the proximal interphalangeal joint at least 8 days after the injury. The hands were divided into two functional categories: Functional category A, normal or nearly normal joint movements, and functional category B, abnormal joint movements. Demographic data were assessed statistically by a univariate analysis following a multiple regression analysis by a stepwise selection. A significant difference was observed between the groups in the number of days from grafting to complete wound healing of the graft site and with or without an escharotomy in the analysis. These parameters were statistically significant predictors of functional category B. The functional outcome of a burned hand after a delayed excision and split-thickness skin graft on the dorsal side became degraded depending on the number of days from grafting to complete wound healing. Cases that underwent an escharotomy also showed deterioration in function.

Cost-Effective Mapping of Benthic Habitats in Inland Reservoirs through Split-Beam Sonar, Indicator Kriging, and Historical Geologic Data

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

Venteris, Erik R.; May, Cassandra

2014-04-23

Because bottom substrate composition is an important control on the temporal and spatial location of the aquatic community, accurate maps of benthic habitats of inland lakes and reservoirs provide valuable information to managers, recreational users, and scientists. Therefore, we collected vertical, split-beam sonar data (roughness [E1], hardness [E2], and bathymetry) and sediment samples to make such maps. Statistical calibration between sonar parameters and sediment classes was problematic because the E1:E2 ratios for soft (muck and clay) sediments overlapped a lower and narrower range for hard (gravel) substrates. Thus, we used indicator kriging (IK) to map the probability that unsampled locationsmore » did not contain coarse sediments. To overcome the calibration issue we tested proxies for the natural processes and anthropogenic history of the reservoir as potential predictive variables. Of these, a geologic map proved to be the most useful. The central alluvial valley and mudflats contained mainly muck and organic-rich clays. The surrounding glacial till and shale bedrock uplands contained mainly poorly sorted gravels. Anomalies in the sonar data suggested that the organic-rich sediments also contained trapped gases, presenting additional interpretive issues for the mapping. We extended the capability of inexpensive split-beam sonar units through the incorporation of historic geologic maps and other records as well as validation with dredge samples. Through the integration of information from multiple data sets, were able to objectively identify bottom substrate and provide reservoir users with an accurate map of available benthic habitat.« less

Cost-Effective Mapping of Benthic Habitats in Inland Reservoirs through Split-Beam Sonar, Indicator Kriging, and Historical Geologic Data

PubMed Central

Venteris, Erik R.; May, Cassandra J.

2014-01-01

Because bottom substrate composition is an important control on the temporal and spatial location of the aquatic community, accurate maps of benthic habitats of inland lakes and reservoirs provide valuable information to managers, recreational users, and scientists. Therefore, we collected vertical, split-beam sonar data (roughness [E1], hardness [E2], and bathymetry) and sediment samples to make such maps. Statistical calibration between sonar parameters and sediment classes was problematic because the E1:E2 ratios for soft (muck and clay) sediments overlapped a lower and narrower range for hard (gravel) substrates. Thus, we used indicator kriging (IK) to map the probability that unsampled locations did not contain coarse sediments. To overcome the calibration issue we tested proxies for the natural processes and anthropogenic history of the reservoir as potential predictive variables. Of these, a geologic map proved to be the most useful. The central alluvial valley and mudflats contained mainly muck and organic-rich clays. The surrounding glacial till and shale bedrock uplands contained mainly poorly sorted gravels. Anomalies in the sonar data suggested that the organic-rich sediments also contained trapped gases, presenting additional interpretive issues for the mapping. We extended the capability of inexpensive split-beam sonar units through the incorporation of historic geologic maps and other records as well as validation with dredge samples. Through the integration of information from multiple data sets, were able to objectively identify bottom substrate and provide reservoir users with an accurate map of available benthic habitat. PMID:24759834

Cost-effective mapping of benthic habitats in inland reservoirs through split-beam sonar, indicator kriging, and historical geologic data.

PubMed

Venteris, Erik R; May, Cassandra J

2014-01-01

Because bottom substrate composition is an important control on the temporal and spatial location of the aquatic community, accurate maps of benthic habitats of inland lakes and reservoirs provide valuable information to managers, recreational users, and scientists. Therefore, we collected vertical, split-beam sonar data (roughness [E1], hardness [E2], and bathymetry) and sediment samples to make such maps. Statistical calibration between sonar parameters and sediment classes was problematic because the E1:E2 ratios for soft (muck and clay) sediments overlapped a lower and narrower range for hard (gravel) substrates. Thus, we used indicator kriging (IK) to map the probability that unsampled locations did not contain coarse sediments. To overcome the calibration issue we tested proxies for the natural processes and anthropogenic history of the reservoir as potential predictive variables. Of these, a geologic map proved to be the most useful. The central alluvial valley and mudflats contained mainly muck and organic-rich clays. The surrounding glacial till and shale bedrock uplands contained mainly poorly sorted gravels. Anomalies in the sonar data suggested that the organic-rich sediments also contained trapped gases, presenting additional interpretive issues for the mapping. We extended the capability of inexpensive split-beam sonar units through the incorporation of historic geologic maps and other records as well as validation with dredge samples. Through the integration of information from multiple data sets, were able to objectively identify bottom substrate and provide reservoir users with an accurate map of available benthic habitat.

The Multiplicity of the Mitotic Centers and the Time-Course of Their Duplication and Separation

PubMed Central

Mazia, Daniel; Harris, Patricia J.; Bibring, Thomas

1960-01-01

In this study, the reproduction of the mitotic centers in the eggs of a sea urchin, Strongylocentrotus purpuratus and a sand dollar Dendraster excentricus has been studied by means of experimental designs that do not depend on the actual visualization of centrioles. The centers are defined in operational terms as potential poles. Blockage of mitosis by mercaptoethanol, it was found, inhibits the duplication of the centers, but does not inhibit the splitting and separation of centers that have already duplicated and thus potential poles could be realized as actual poles in multipolar divisions. At all times, the center is at least a duplex structure; that is, it contains two potential poles. The actual duplication process is the earliest event in a given mitotic cycle, taking place at very early interphase or in late telophase of the previous division. The splitting of the centers following duplication is a distinct process, dissociable from the duplication as such. Duplication and splitting normally occur at about the same time in the mitotic cycle, with a precession of the former. That is, as the two members of a pair of "old" centers split, each one gives rise to a new one, which remains associated with it until the next phase of splitting and duplication occurs. The results are consistent with what is termed a "generative" model of the self-reproduction of an intracellular body. According to this, the body does not immediately produce a full-fledged copy of itself, with simultaneous fission, but the primary duplication event involves only a part of the parent structure. This gives rise to a "germ" or "seed" which then grows to be equivalent to the parent body, and finally splits from it. PMID:19866563

A Fiber-Based Ratiometric Optical Cardiac Mapping Channel Using a Diffraction Grating and Split Detector

PubMed Central

Brown, Ninita H.; Dobrovolny, Hana M.; Gauthier, Daniel J.; Wolf, Patrick D.

2007-01-01

Optical fiber-based mapping systems are used to record the cardiac action potential (AP) throughout the myocardium. The optical AP contains a contraction-induced motion artifact (MA), which makes it difficult to accurately measure the action potential duration (APD). MA is removed by preventing contraction with electrical-mechanical uncoupling drugs, such as 2,3-butanedione monoxime (BDM). We designed a novel fiber-based ratiometric optical channel using a blue light emitting diode, a diffraction grating, and a split photodetector that can accurately measure the cardiac AP without the need for BDM. The channel was designed based on simulations using the optical design software ZEMAX. The channel has an electrical bandwidth of 150 Hz and an root mean-square dark noise of 742 μV. The channel successfully recorded the cardiac AP from the wall of five rabbit heart preparations without the use of BDM. After 20-point median filtering, the mean signal/noise ratio was 25.3 V/V. The APD measured from the base of a rabbit heart was 134 ± 8.4 ms, compared to 137.6 ± 3.3 ms from simultaneous microelectrode recordings. This difference was not statistically significant (p-value = 0.3). The quantity of MA removed was also measured using the motion ratio. The reduction in MA was significant (p-value = 0.0001). This fiber-based system is the first of its kind to enable optical APD measurements in the beating heart wall without the use of BDM. PMID:17416627

Irrational beliefs, attitudes about competition, and splitting.

PubMed

Watson, P J; Morris, R J; Miller, L

2001-03-01

Rational-Emotive Behavior Therapy (REBT) theoretically promotes actualization of both individualistic and social-oriented potentials. In a test of this assumption, the Belief Scale and subscales from the Survey of Personal Beliefs served as measures of what REBT presumes to be pathogenic irrationalities. These measures were correlated with the Hypercompetitive Attitude Scale (HCAS), the Personal Development Competitive Attitude Scale (PDCAS), factors from the Splitting Index, and self-esteem. Results for the HCAS and Self-Splitting supported the REBT claim about individualistic self-actualization. Mostly nonsignificant and a few counterintuitive linkages were observed for irrational beliefs with the PDCAS, Family-Splitting, and Other-Splitting, and these data suggested that REBT may be less successful in capturing the "rationality" of a social-oriented self-actualization. Copyright 2001 John Wiley & Sons, Inc.

Application of RF-MEMS-Based Split Ring Resonators (SRRs) to the Implementation of Reconfigurable Stopband Filters: A Review

PubMed Central

Martín, Ferran; Bonache, Jordi

2014-01-01

In this review paper, several strategies for the implementation of reconfigurable split ring resonators (SRRs) based on RF-MEMS switches are presented. Essentially three types of RF-MEMS combined with split rings are considered: (i) bridge-type RF-MEMS on top of complementary split ring resonators CSRRs; (ii) cantilever-type RF-MEMS on top of SRRs; and (iii) cantilever-type RF-MEMS integrated with SRRs (or RF-MEMS SRRs). Advantages and limitations of these different configurations from the point of view of their potential applications for reconfigurable stopband filter design are discussed, and several prototype devices are presented. PMID:25474378

Statistical Approaches to Adjusting Weights for Dependent Arms in Network Meta-analysis.

PubMed

Su, Yu-Xuan; Tu, Yu-Kang

2018-05-22

Network meta-analysis compares multiple treatments in terms of their efficacy and harm by including evidence from randomized controlled trials. Most clinical trials use parallel design, where patients are randomly allocated to different treatments and receive only one treatment. However, some trials use within person designs such as split-body, split-mouth and cross-over designs, where each patient may receive more than one treatment. Data from treatment arms within these trials are no longer independent, so the correlations between dependent arms need to be accounted for within the statistical analyses. Ignoring these correlations may result in incorrect conclusions. The main objective of this study is to develop statistical approaches to adjusting weights for dependent arms within special design trials. In this study, we demonstrate the following three approaches: the data augmentation approach, the adjusting variance approach, and the reducing weight approach. These three methods could be perfectly applied in current statistic tools such as R and STATA. An example of periodontal regeneration was used to demonstrate how these approaches could be undertaken and implemented within statistical software packages, and to compare results from different approaches. The adjusting variance approach can be implemented within the network package in STATA, while reducing weight approach requires computer software programming to set up the within-study variance-covariance matrix. This article is protected by copyright. All rights reserved.

An easy, rapid, and reproducible way to create a split-thickness wound for experimental purposes.

PubMed

Gümüş, Nazim; Özkaya, Neşe Kurt; Bulut, Hüseyin Eray; Yilmaz, Sarper

2014-09-01

Partial-thickness wound models of rat skin have some difficulties in creating the wounds in equal size and depth. Moreover, making a split-thickness wound on the rat skin seems not to be simple and rapid. A new alternative method was presented here to overcome these obstacles, by using a waterjet device to create a split-thickness wound on rat skin. Twenty-four male Wistar rats were randomly divided into 3 groups. An area of 4 × 4 cm in diameter was marked on the center of the dorsal skin. Waterjet hydrosurgery system was used to create a wound on the dorsal rat skin, by removing the outer layers of the skin. In group 1, rat skin was wounded with setting 1 to create a superficial skin wound. In group 2, it was injured with setting 5 to make a deeper wound, and in group 3, skin wound was performed with setting 10 making the deepest wound in the experiment. After the wounds were created on the rat skin, a full-thickness skin biopsy was taken from the middle of the cranial margin of the wound, including both the wound surface and the healthy skin in a specimen. Healing time of the wounds of animals was recorded in the experiment groups. Then, the results were compared statistically between the groups. In the histologic assessment, both the thickness of the remnant of the epidermis in the wound surface and the thickness of the healthy epidermis were measured under light microscope. Thickness of the epidermis remaining after wounding was statistically compared among the groups and with the healthy epidermis. The mean thickness of the remaining epidermis was determined for each group. It was higher in the superficial wounds than in the deep wounds, because of the removal of the skin from its outer surface through the deep layers of the skin with waterjet device. The most superficial wound in the experiment was observed in group 1, which was statistically different from the wounds of group 3, whereas there was no difference between the wounds of groups 1 and 2. Compared with the wounds of groups 1 and 2, the wounds in group 3 were significantly deeper than the wounds of other groups, which was statistically significant. In all groups, mean thickness of epidermis in the wound surface showed statistically significant difference from that in the healthy skin. When compared with the healing times of the wounds in the groups, a statistically significant difference was found between them. Creation of a split-skin wound, by using the waterjet system, provides a wound in reproducible size and depth, also in a standardized and rapid manner. Moreover, it makes precise and controlled wound creation in the rat skin.

Isoniazid, Pyrazinamide and Rifampicin Content Variation in Split Fixed-Dose Combination Tablets

PubMed Central

Pouplin, Thomas; Phuong, Pham Nguyen; Toi, Pham Van; Nguyen Pouplin, Julie; Farrar, Jeremy

2014-01-01

Setting In most developing countries, paediatric tuberculosis is treated with split tablets leading to potential inaccuracy in the dose delivery and drug exposure. There is no data on the quality of first-line drugs content in split fixed-dose combination tablets. Objective To determine Isoniazid, Pyrazinamide and Rifampicin content uniformity in split FDC tablets used in the treatment of childhood tuberculosis. Design Drug contents of 15 whole tablets, 30 half tablets and 36 third tablets were analysed by high performance liquid chromatography. The content uniformity was assessed by comparing drug content measured in split portions with their expected amounts and the quality of split portions was assessed applying qualitative specifications for whole tablets. Results All whole tablets measurements fell into the USP proxy for the three drugs. But a significant number of half and third portions was found outside the tolerated variation range and the split formulation failed the requirements for content uniformity. To correct for the inaccuracy of splitting the tablets into equal portions, a weight-adjustment strategy was used but this did not improve the findings. Conclusion In split tablets the content of the three drugs is non-uniform and exceeded the USP recommendations. There is an absolute need to make child-friendly formulations available for the treatment of childhood tuberculosis. PMID:25004128

Isoniazid, pyrazinamide and rifampicin content variation in split fixed-dose combination tablets.

PubMed

Pouplin, Thomas; Phuong, Pham Nguyen; Toi, Pham Van; Nguyen Pouplin, Julie; Farrar, Jeremy

2014-01-01

In most developing countries, paediatric tuberculosis is treated with split tablets leading to potential inaccuracy in the dose delivery and drug exposure. There is no data on the quality of first-line drugs content in split fixed-dose combination tablets. To determine Isoniazid, Pyrazinamide and Rifampicin content uniformity in split FDC tablets used in the treatment of childhood tuberculosis. Drug contents of 15 whole tablets, 30 half tablets and 36 third tablets were analysed by high performance liquid chromatography. The content uniformity was assessed by comparing drug content measured in split portions with their expected amounts and the quality of split portions was assessed applying qualitative specifications for whole tablets. All whole tablets measurements fell into the USP proxy for the three drugs. But a significant number of half and third portions was found outside the tolerated variation range and the split formulation failed the requirements for content uniformity. To correct for the inaccuracy of splitting the tablets into equal portions, a weight-adjustment strategy was used but this did not improve the findings. In split tablets the content of the three drugs is non-uniform and exceeded the USP recommendations. There is an absolute need to make child-friendly formulations available for the treatment of childhood tuberculosis.

Cavity-assisted emission of polarization-entangled photons from biexcitons in quantum dots with fine-structure splitting.

PubMed

Schumacher, Stefan; Förstner, Jens; Zrenner, Artur; Florian, Matthias; Gies, Christopher; Gartner, Paul; Jahnke, Frank

2012-02-27

We study the quantum properties and statistics of photons emitted by a quantum-dot biexciton inside a cavity. In the biexciton-exciton cascade, fine-structure splitting between exciton levels degrades polarization-entanglement for the emitted pair of photons. However, here we show that the polarization-entanglement can be preserved in such a system through simultaneous emission of two degenerate photons into cavity modes tuned to half the biexciton energy. Based on detailed theoretical calculations for realistic quantum-dot and cavity parameters, we quantify the degree of achievable entanglement.

InGaAs/InAlAs Double Quantum Wells as Starting Structures for Quantum Logic Gates

NASA Astrophysics Data System (ADS)

Marchewka, M.; Sheregii, E. M.

2011-12-01

The detection of both symmetric and anti-symmetric electron states in DQWs by an optical method is described in this paper. Values of the symmetric and anti-symmetric splitting (SAS-gap) determined in this way are used for interpretation of the beating effect in the SdH oscillations observed at low temperatures in the external magnetic field. SAS-splitting of electron states in DQWs clearly exists at room temperature and electrons in symmetric and anti-symmetric states have different statistics so these states can be identified in electron transport.

Effect of Split Gate Size on the Electrostatic Potential and 0.7 Anomaly within Quantum Wires on a Modulation-Doped GaAs /AlGaAs Heterostructure

NASA Astrophysics Data System (ADS)

Smith, L. W.; Al-Taie, H.; Lesage, A. A. J.; Thomas, K. J.; Sfigakis, F.; See, P.; Griffiths, J. P.; Farrer, I.; Jones, G. A. C.; Ritchie, D. A.; Kelly, M. J.; Smith, C. G.

2016-04-01

We study 95 split gates of different size on a single chip using a multiplexing technique. Each split gate defines a one-dimensional channel on a modulation-doped GaAs /AlGaAs heterostructure, through which the conductance is quantized. The yield of devices showing good quantization decreases rapidly as the length of the split gates increases. However, for the subset of devices showing good quantization, there is no correlation between the electrostatic length of the one-dimensional channel (estimated using a saddle-point model) and the gate length. The variation in electrostatic length and the one-dimensional subband spacing for devices of the same gate length exceeds the variation in the average values between devices of different lengths. There is a clear correlation between the curvature of the potential barrier in the transport direction and the strength of the "0.7 anomaly": the conductance value of the 0.7 anomaly reduces as the barrier curvature becomes shallower. These results highlight the key role of the electrostatic environment in one-dimensional systems. Even in devices with clean conductance plateaus, random fluctuations in the background potential are crucial in determining the potential landscape in the active device area such that nominally identical gate structures have different characteristics.

The Interaction of Fatigue and Potentiation Following an Acute Bout of Unilateral Squats.

PubMed

Andrews, Samantha K; Horodyski, Jesse M; MacLeod, Daniel A; Whitten, Joseph; Behm, David G

2016-12-01

A prior conditioning resistance exercise can augment subsequent performance of the affected muscles due to the effects of post-activation potentiation (PAP). The non-local muscle fatigue literature has illustrated the global neural effects of unilateral fatigue. However, no studies have examined the possibility of acute non-local performance enhancements. The objective of the study was to provide a conditioning stimulus in an attempt to potentiate the subsequent jump performance of the affected limb and determine if there were performance changes in the contralateral limb. Using a randomized allocation, 14 subjects (6 females, 8 males) completed three conditions on separate days: 1) unilateral, dominant leg, Bulgarian split squat protocol with testing of the exercised leg, 2) unilateral, dominant leg, Bulgarian split squat protocol with testing of the contralateral, non-exercised leg and 3) control session with testing of the non-dominant leg. Pre- and post-testing consisted of countermovement (CMJ) and drop jumps (DJ). The exercised leg exhibited CMJ height increases of 3.5% (p = 0.008; d = 0.28), 4.0% (p = 0.011; d = 0.33) and 3.2% (p = 0.013; d = 0.26) at 1, 5, and 10 min post-intervention respectively. The contralateral CMJ height had 2.0% (p = 0.034; d = 0.18), 1.2% (p = 0.2; d = 0.12), and 2.1% (p = 0.05; d = 0.17) deficits at 1, 5, and 10 min post-intervention respectively. Similar relative results were found for CMJ power. There were no significant interactions for DJ measures or control CMJ measures. The findings suggest that PAP effects were likely predominant for the exercised leg whereas the conditioning exercise provided trivial magnitude although statistically significant neural impairments for the contralateral limb.

Urban Data Book : Volume 2. Urban Data - Milwaukee-Washington, Notes and Technical Appendixes

DOT National Transportation Integrated Search

1975-11-01

A quick reference compilation of certain population, socio-economic, employment, and modal split characteristics of the 35 largest Standard Metropolitan Statistical Areas (SMSA) in the United States is presented. The three basic groups of urban data ...

Perovskite nanocomposites as effective CO2-splitting agents in a cyclic redox scheme

PubMed Central

Zhang, Junshe; Haribal, Vasudev; Li, Fanxing

2017-01-01

We report iron-containing mixed-oxide nanocomposites as highly effective redox materials for thermochemical CO2 splitting and methane partial oxidation in a cyclic redox scheme, where methane was introduced as an oxygen “sink” to promote the reduction of the redox materials followed by reoxidation through CO2 splitting. Up to 96% syngas selectivity in the methane partial oxidation step and close to complete conversion of CO2 to CO in the CO2-splitting step were achieved at 900° to 980°C with good redox stability. The productivity and production rate of CO in the CO2-splitting step were about seven times higher than those in state-of-the-art solar-thermal CO2-splitting processes, which are carried out at significantly higher temperatures. The proposed approach can potentially be applied for acetic acid synthesis with up to 84% reduction in CO2 emission when compared to state-of-the-art processes. PMID:28875171

Small-bubble transport and splitting dynamics in a symmetric bifurcation.

PubMed

Qamar, Adnan; Warnez, Matthew; Valassis, Doug T; Guetzko, Megan E; Bull, Joseph L

2017-08-01

Simulations of small bubbles traveling through symmetric bifurcations are conducted to garner information pertinent to gas embolotherapy, a potential cancer treatment. Gas embolotherapy procedures use intra-arterial bubbles to occlude tumor blood supply. As bubbles pass through bifurcations in the blood stream nonhomogeneous splitting and undesirable bioeffects may occur. To aid development of gas embolotherapy techniques, a volume of fluid method is used to model the splitting process of gas bubbles passing through artery and arteriole bifurcations. The model reproduces the variety of splitting behaviors observed experimentally, including the bubble reversal phenomenon. Splitting homogeneity and maximum shear stress along the vessel walls is predicted over a variety of physical parameters. Small bubbles, having initial length less than twice the vessel diameter, were found unlikely to split in the presence of gravitational asymmetry. Maximum shear stresses were found to decrease exponentially with increasing Reynolds number. Vortex-induced shearing near the bifurcation is identified as a possible mechanism for endothelial cell damage.

Nano-ferrites for Water Splitting: Unprecedented High Photocatalytic Hydrogen Production under Visible Light

EPA Science Inventory

In the present investigation, hydrogen production via water splitting by nano ferrites has been studied using ethanol as the sacrificial donor. The nano ferrite has shown great potential in hydrogen generation with hydrogen yield of 8275 9moles/h/ g of photocatalyst under visible...

Can Pacing Be Regulated by Post-Activation Potentiation? Insights from a Self-Paced 30 km Trial in Half-Marathon Runners

PubMed Central

Del Rosso, Sebastián; Barros, Edilberto; Tonello, Laís; Oliveira-Silva, Iransé; Behm, David G.; Foster, Carl; Boullosa, Daniel A.

2016-01-01

Purpose Given the co-existence of post-activation potentiation (PAP) and fatigue within muscle, it is not known whether PAP could influence performance and pacing during distance running by moderating fatigue. The aim of this study was to assess the influence of PAP on pacing, jumping and other physiological measures during a self-paced 30 km trial. Methods Eleven male endurance-trained runners (half-marathon runners) volunteered to participate in this study. Runners participated in a multi-stage 30 km trial. Before the trial started, determination of baseline blood lactate (bLa) and countermovement jump (CMJ) height was performed. The self-paced 30 km trial consisted of 6 × 5 km splits. At the end of each 5 km split (60 s break), data on time to complete the split, CMJ height, Rating of Perceived Exertion (RPE) and blood lactate were collected while heart rate was continuously monitored. Results There was a significant decrease in speed (e.g. positive pacing strategy after the 4th split, p<0.05) with a progressive increase in RPE throughout the trial. Compared with baseline, CMJ height was significantly (p<0.05) greater than baseline and was maintained until the end of the trial with an increase after the 5th split, concomitant with a significant reduction in speed and an increase in RPE. Significant correlations were found between ΔCMJ and ΔSPEED (r = 0.77 to 0.87, p<0.05) at different time points as well as between RPE and speed (r = -0.61 to -0.82, p<0.05). Conclusion Our results indicates that fatigue and potentiation co-exist during long lasting endurance events, and that the observed increase in jump performance towards the end of the trial could be reflecting a greater potentiation potentially perhaps counteracting the effects of fatigue and preventing further reductions in speed. PMID:26934357

Neutron-proton effective mass splitting in neutron-rich matter and its impacts on nuclear reactions

NASA Astrophysics Data System (ADS)

Li, Bao-An; Chen, Lie-Wen

2015-04-01

The neutron-proton effective mass splitting in neutron-rich nucleonic matter reflects the spacetime nonlocality of the isovector nuclear interaction. It affects the neutron/proton ratio during the earlier evolution of the Universe, cooling of proto-neutron stars, structure of rare isotopes and dynamics of heavy-ion collisions. While there is still no consensus on whether the neutron-proton effective mass splitting is negative, zero or positive and how it depends on the density as well as the isospin-asymmetry of the medium, significant progress has been made in recent years in addressing these issues. There are different kinds of nucleon effective masses. In this mini-review, we focus on the total effective masses often used in the non-relativistic description of nuclear dynamics. We first recall the connections among the neutron-proton effective mass splitting, the momentum dependence of the isovector potential and the density dependence of the symmetry energy. We then make a few observations about the progress in calculating the neutron-proton effective mass splitting using various nuclear many-body theories and its effects on the isospin-dependence of in-medium nucleon-nucleon cross-sections. Perhaps, our most reliable knowledge so far about the neutron-proton effective mass splitting at saturation density of nuclear matter comes from optical model analyses of huge sets of nucleon-nucleus scattering data accumulated over the last five decades. The momentum dependence of the symmetry potential from these analyses provide a useful boundary condition at saturation density for calibrating nuclear many-body calculations. Several observables in heavy-ion collisions have been identified as sensitive probes of the neutron-proton effective mass splitting in dense neutron-rich matter based on transport model simulations. We review these observables and comment on the latest experimental findings.

On Valence-Band Splitting in Layered MoS2.

PubMed

Zhang, Youwei; Li, Hui; Wang, Haomin; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun

2015-08-25

As a representative two-dimensional semiconducting transition-metal dichalcogenide (TMD), the electronic structure in layered MoS2 is a collective result of quantum confinement, interlayer interaction, and crystal symmetry. A prominent energy splitting in the valence band gives rise to many intriguing electronic, optical, and magnetic phenomena. Despite numerous studies, an experimental determination of valence-band splitting in few-layer MoS2 is still lacking. Here, we show how the valence-band maximum (VBM) splits for one to five layers of MoS2. Interlayer coupling is found to contribute significantly to phonon energy but weakly to VBM splitting in bilayers, due to a small interlayer hopping energy for holes. Hence, spin-orbit coupling is still predominant in the splitting. A temperature-independent VBM splitting, known for single-layer MoS2, is, thus, observed for bilayers. However, a Bose-Einstein type of temperature dependence of VBM splitting prevails in three to five layers of MoS2. In such few-layer MoS2, interlayer coupling is enhanced with a reduced interlayer distance, but thermal expansion upon temperature increase tends to decouple adjacent layers and therefore decreases the splitting energy. Our findings that shed light on the distinctive behaviors about VBM splitting in layered MoS2 may apply to other hexagonal TMDs as well. They will also be helpful in extending our understanding of the TMD electronic structure for potential applications in electronics and optoelectronics.

Analysis of selected volatile organic compounds in split and nonsplit swiss cheese samples using selected-ion flow tube mass spectrometry (SIFT-MS).

PubMed

Castada, Hardy Z; Wick, Cheryl; Taylor, Kaitlyn; Harper, W James

2014-04-01

Splits/cracks are recurring product defects that negatively affect the Swiss cheese industry. Investigations to understand the biophysicochemical aspects of these defects, and thus determine preventive measures against their occurrence, are underway. In this study, selected-ion, flow tube mass spectrometry was employed to determine the volatile organic compound (VOC) profiles present in the headspace of split compared with nonsplit cheeses. Two sampling methodologies were employed: split compared with nonsplit cheese vat pair blocks; and comparison of blind, eye, and split segments within cheese blocks. The variability in VOC profiles was examined to evaluate the potential biochemical pathway chemistry differences within and between cheese samples. VOC profile inhomogeneity was most evident in cheeses between factories. Evaluation of biochemical pathways leading to the formation of key VOCs differentiating the split from the blind and eye segments within factories indicated release of additional carbon dioxide by-product. These results suggest a factory-dependent cause of split formation that could develop from varied fermentation pathways in the blind, eye, and split areas within a cheese block. The variability of VOC profiles within and between factories exhibit varied biochemical fermentation pathways that could conceivably be traced back in the making process to identify parameters responsible for split defect. © 2014 Institute of Food Technologists®

Association Splitting: A randomized controlled trial of a new method to reduce craving among inpatients with alcohol dependence.

PubMed

Schneider, Brooke C; Moritz, Steffen; Hottenrott, Birgit; Reimer, Jens; Andreou, Christina; Jelinek, Lena

2016-04-30

Association Splitting, a novel cognitive intervention, was tested in patients with alcohol dependence as an add-on intervention in an initial randomized controlled trial. Preliminary support for Association Splitting has been found in patients with obsessive-compulsive disorder, as well as in an online pilot study of patients with alcohol use disorders. The present variant sought to reduce craving by strengthening neutral associations with alcohol-related stimuli, thus, altering cognitive networks. Eighty-four inpatients with verified diagnoses of alcohol dependence, who were currently undergoing inpatient treatment, were randomly assigned to Association Splitting or Exercise Therapy. Craving was measured at baseline, 4-week follow-up, and six months later with the Obsessive-Compulsive Drinking Scale (primary outcome) and the Alcohol Craving Questionnaire. There was no advantage for Association Splitting after three treatment sessions relative to Exercise Therapy. Among Association Splitting participants, 51.9% endorsed a subjective decline in craving and 88.9% indicated that they would use Association Splitting in the future. Despite high acceptance, an additional benefit of Association Splitting beyond standard inpatient treatment was not found. Given that participants were concurrently undergoing inpatient treatment and Association Splitting has previously shown moderate effects, modification of the study design may improve the potential to detect significant effects in future trials. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

An ab initio potential energy surface for the formic acid dimer: zero-point energy, selected anharmonic fundamental energies, and ground-state tunneling splitting calculated in relaxed 1-4-mode subspaces.

PubMed

Qu, Chen; Bowman, Joel M

2016-09-14

We report a full-dimensional, permutationally invariant potential energy surface (PES) for the cyclic formic acid dimer. This PES is a least-squares fit to 13475 CCSD(T)-F12a/haTZ (VTZ for H and aVTZ for C and O) energies. The energy-weighted, root-mean-square fitting error is 11 cm -1 and the barrier for the double-proton transfer on the PES is 2848 cm -1 , in good agreement with the directly-calculated ab initio value of 2853 cm -1 . The zero-point vibrational energy of 15 337 ± 7 cm -1 is obtained from diffusion Monte Carlo calculations. Energies of fundamentals of fifteen modes are calculated using the vibrational self-consistent field and virtual-state configuration interaction method. The ground-state tunneling splitting is computed using a reduced-dimensional Hamiltonian with relaxed potentials. The highest-level, four-mode coupled calculation gives a tunneling splitting of 0.037 cm -1 , which is roughly twice the experimental value. The tunneling splittings of (DCOOH) 2 and (DCOOD) 2 from one to three mode calculations are, as expected, smaller than that for (HCOOH) 2 and consistent with experiment.

Visualizing multiple inter-organelle contact sites using the organelle-targeted split-GFP system.

PubMed

Kakimoto, Yuriko; Tashiro, Shinya; Kojima, Rieko; Morozumi, Yuki; Endo, Toshiya; Tamura, Yasushi

2018-04-18

Functional integrity of eukaryotic organelles relies on direct physical contacts between distinct organelles. However, the entity of organelle-tethering factors is not well understood due to lack of means to analyze inter-organelle interactions in living cells. Here we evaluate the split-GFP system for visualizing organelle contact sites in vivo and show its advantages and disadvantages. We observed punctate GFP signals from the split-GFP fragments targeted to any pairs of organelles among the ER, mitochondria, peroxisomes, vacuole and lipid droplets in yeast cells, which suggests that these organelles form contact sites with multiple organelles simultaneously although it is difficult to rule out the possibilities that these organelle contacts sites are artificially formed by the irreversible associations of the split-GFP probes. Importantly, split-GFP signals in the overlapped regions of the ER and mitochondria were mainly co-localized with ERMES, an authentic ER-mitochondria tethering structure, suggesting that split-GFP assembly depends on the preexisting inter-organelle contact sites. We also confirmed that the split-GFP system can be applied to detection of the ER-mitochondria contact sites in HeLa cells. We thus propose that the split-GFP system is a potential tool to observe and analyze inter-organelle contact sites in living yeast and mammalian cells.

Direct reconstruction of pharmacokinetic parameters in dynamic fluorescence molecular tomography by the augmented Lagrangian method

NASA Astrophysics Data System (ADS)

Zhu, Dianwen; Zhang, Wei; Zhao, Yue; Li, Changqing

2016-03-01

Dynamic fluorescence molecular tomography (FMT) has the potential to quantify physiological or biochemical information, known as pharmacokinetic parameters, which are important for cancer detection, drug development and delivery etc. To image those parameters, there are indirect methods, which are easier to implement but tend to provide images with low signal-to-noise ratio, and direct methods, which model all the measurement noises together and are statistically more efficient. The direct reconstruction methods in dynamic FMT have attracted a lot of attention recently. However, the coupling of tomographic image reconstruction and nonlinearity of kinetic parameter estimation due to the compartment modeling has imposed a huge computational burden to the direct reconstruction of the kinetic parameters. In this paper, we propose to take advantage of both the direct and indirect reconstruction ideas through a variable splitting strategy under the augmented Lagrangian framework. Each iteration of the direct reconstruction is split into two steps: the dynamic FMT image reconstruction and the node-wise nonlinear least squares fitting of the pharmacokinetic parameter images. Through numerical simulation studies, we have found that the proposed algorithm can achieve good reconstruction results within a small amount of time. This will be the first step for a combined dynamic PET and FMT imaging in the future.

Contrast-enhanced dual-energy subtraction imaging using electronic spectrum-splitting and multi-prism x-ray lenses

NASA Astrophysics Data System (ADS)

Fredenberg, Erik; Cederström, Björn; Lundqvist, Mats; Ribbing, Carolina; Åslund, Magnus; Diekmann, Felix; Nishikawa, Robert; Danielsson, Mats

2008-03-01

Dual-energy subtraction imaging (DES) is a method to improve the detectability of contrast agents over a lumpy background. Two images, acquired at x-ray energies above and below an absorption edge of the agent material, are logarithmically subtracted, resulting in suppression of the signal from the tissue background and a relative enhancement of the signal from the agent. Although promising, DES is still not widely used in clinical practice. One reason may be the need for two distinctly separated x-ray spectra that are still close to the absorption edge, realized through dual exposures which may introduce motion unsharpness. In this study, electronic spectrum-splitting with a silicon-strip detector is theoretically and experimentally investigated for a mammography model with iodinated contrast agent. Comparisons are made to absorption imaging and a near-ideal detector using a signal-to-noise ratio that includes both statistical and structural noise. Similar to previous studies, heavy absorption filtration was needed to narrow the spectra at the expense of a large reduction in x-ray flux. Therefore, potential improvements using a chromatic multi-prism x-ray lens (MPL) for filtering were evaluated theoretically. The MPL offers a narrow tunable spectrum, and we show that the image quality can be improved compared to conventional filtering methods.

Measuring and Evaluating TCP Splitting for Cloud Services

NASA Astrophysics Data System (ADS)

Pathak, Abhinav; Wang, Y. Angela; Huang, Cheng; Greenberg, Albert; Hu, Y. Charlie; Kern, Randy; Li, Jin; Ross, Keith W.

In this paper, we examine the benefits of split-TCP proxies, deployed in an operational world-wide network, for accelerating cloud services. We consider a fraction of a network consisting of a large number of satellite datacenters, which host split-TCP proxies, and a smaller number of mega datacenters, which ultimately perform computation or provide storage. Using web search as an exemplary case study, our detailed measurements reveal that a vanilla TCP splitting solution deployed at the satellite DCs reduces the 95 th percentile of latency by as much as 43% when compared to serving queries directly from the mega DCs. Through careful dissection of the measurement results, we characterize how individual components, including proxy stacks, network protocols, packet losses and network load, can impact the latency. Finally, we shed light on further optimizations that can fully realize the potential of the TCP splitting solution.

Recent Advances in Bismuth-Based Nanomaterials for Photoelectrochemical Water Splitting.

PubMed

Bhat, Swetha S M; Jang, Ho Won

2017-08-10

In recent years, bismuth-based nanomaterials have drawn considerable interest as potential candidates for photoelectrochemical (PEC) water splitting owing to their narrow band gaps, nontoxicity, and low costs. The unique electronic structure of bismuth-based materials with a well-dispersed valence band comprising Bi 6s and O 2p orbitals offers a suitable band gap to harvest visible light. This Review presents significant advancements in exploiting bismuth-based nanomaterials for solar water splitting. An overview of the different strategies employed and the new ideas adopted to improve the PEC performance of bismuth-based nanomaterials are discussed. Morphology control, the construction of heterojunctions, doping, and co-catalyst loading are several approaches that are implemented to improve the efficiency of solar water splitting. Key issues are identified and guidelines are suggested to rationalize the design of efficient bismuth-based materials for sunlight-driven water splitting. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nitrous Oxide (N2O) Emissions in Wheat and Canola Crops under Fertigation Management in the Canadian Prairies

NASA Astrophysics Data System (ADS)

Chai, L.; Hernandez Ramirez, G.; Dyck, M. F.; Pauly, D.; Kryzanowski, L.; Middleton, A.; Powers, L. A.; Lohstraeter, G.; Werk, D.

2016-12-01

Nitrous oxide (N2O) emissions from agricultural soils contribute significantly to the amount of greenhouse gases released to the atmosphere every year. Farming practices, such as fertigation in which nitrogen fertilizer is added to crops through irrigation water, could increase the risk for N2O losses. To assess the effect of N fertigation rates on N2O production, field chambers were used to collect weekly gas samples throughout the 2015 growing season in wheat (Triticum aestivum) and canola (Brassica Napus) plots in southern Alberta, Canada. Synthetic fertilizer was either added at seeding or both added at seeding and through irrigation water at one early crop growth stage. The 6 fertilizer treatments were: 60, 90 and 120 kg N ha-1 added at seeding in early May, and 30, 60 and 90 kg N ha-1 at seeding plus another 30 kg N ha-1 added through fertigation in mid-June. Controls with no fertilizer were also evaluated, and each treatment was replicated 4 times. In the wheat plots at a fertilization rate of 120 kg N ha-1, irrespective of single or split application, a larger N2O flux was produced compared to the control (P = 0.024). Similarly, in canola, a total N addition of 90 kg N ha-1 also led to larger N2O fluxes than the control (P = 0.035). The use of fertigation to split the N application had no effect on the N2O emissions in canola; however, in wheat, there was a statistical difference between emissions from 90 kg N ha-1 added all at seeding versus 90 kg N ha-1 split between seeding (60) and fertigation (30); splitting the fertilizer resulted in a 62% decrease in the overall N2O emissions (324 g vs. 524 g N2O-N ha-1; P = 0.039). No other N rates resulted in statistically different N2O emissions when N application was split. These results suggest that fertigation can reduce N2O emissions, but only at moderate N rates (90 kg ha-1 yr-1); conversely, when lower (60) or higher (120) rates are split, emissions remain unaffected.

Does rational selection of training and test sets improve the outcome of QSAR modeling?

PubMed

Martin, Todd M; Harten, Paul; Young, Douglas M; Muratov, Eugene N; Golbraikh, Alexander; Zhu, Hao; Tropsha, Alexander

2012-10-22

Prior to using a quantitative structure activity relationship (QSAR) model for external predictions, its predictive power should be established and validated. In the absence of a true external data set, the best way to validate the predictive ability of a model is to perform its statistical external validation. In statistical external validation, the overall data set is divided into training and test sets. Commonly, this splitting is performed using random division. Rational splitting methods can divide data sets into training and test sets in an intelligent fashion. The purpose of this study was to determine whether rational division methods lead to more predictive models compared to random division. A special data splitting procedure was used to facilitate the comparison between random and rational division methods. For each toxicity end point, the overall data set was divided into a modeling set (80% of the overall set) and an external evaluation set (20% of the overall set) using random division. The modeling set was then subdivided into a training set (80% of the modeling set) and a test set (20% of the modeling set) using rational division methods and by using random division. The Kennard-Stone, minimal test set dissimilarity, and sphere exclusion algorithms were used as the rational division methods. The hierarchical clustering, random forest, and k-nearest neighbor (kNN) methods were used to develop QSAR models based on the training sets. For kNN QSAR, multiple training and test sets were generated, and multiple QSAR models were built. The results of this study indicate that models based on rational division methods generate better statistical results for the test sets than models based on random division, but the predictive power of both types of models are comparable.

Potential-splitting approach applied to the Temkin-Poet model for electron scattering off the hydrogen atom and the helium ion

NASA Astrophysics Data System (ADS)

Yarevsky, E.; Yakovlev, S. L.; Larson, Å; Elander, N.

2015-06-01

The study of scattering processes in few body systems is a difficult problem especially if long range interactions are involved. In order to solve such problems, we develop here a potential-splitting approach for three-body systems. This approach is based on splitting the reaction potential into a finite range core part and a long range tail part. The solution to the Schrödinger equation for the long range tail Hamiltonian is found analytically, and used as an incoming wave in the three body scattering problem. This reformulation of the scattering problem makes it suitable for treatment by the exterior complex scaling technique in the sense that the problem after the complex dilation is reduced to a boundary value problem with zero boundary conditions. We illustrate the method with calculations on the electron scattering off the hydrogen atom and the positive helium ion in the frame of the Temkin-Poet model.

The dimension split element-free Galerkin method for three-dimensional potential problems

NASA Astrophysics Data System (ADS)

Meng, Z. J.; Cheng, H.; Ma, L. D.; Cheng, Y. M.

2018-06-01

This paper presents the dimension split element-free Galerkin (DSEFG) method for three-dimensional potential problems, and the corresponding formulae are obtained. The main idea of the DSEFG method is that a three-dimensional potential problem can be transformed into a series of two-dimensional problems. For these two-dimensional problems, the improved moving least-squares (IMLS) approximation is applied to construct the shape function, which uses an orthogonal function system with a weight function as the basis functions. The Galerkin weak form is applied to obtain a discretized system equation, and the penalty method is employed to impose the essential boundary condition. The finite difference method is selected in the splitting direction. For the purposes of demonstration, some selected numerical examples are solved using the DSEFG method. The convergence study and error analysis of the DSEFG method are presented. The numerical examples show that the DSEFG method has greater computational precision and computational efficiency than the IEFG method.

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

Sousa-Silva, Clara; Tennyson, Jonathan; Yurchenko, Sergey N.

Splitting due to tunnelling via the potential energy barrier has played a significant role in the study of molecular spectra since the early days of spectroscopy. The observation of the ammonia doublet led to attempts to find a phosphine analogous, but these have so far failed due to its considerably higher barrier. Full dimensional, variational nuclear motion calculations are used to predict splittings as a function of excitation energy. Simulated spectra suggest that such splittings should be observable in the near infrared via overtones of the ν{sub 2} bending mode starting with 4ν{sub 2}.

Time-dependent Reliability of Dynamic Systems using Subset Simulation with Splitting over a Series of Correlated Time Intervals

DTIC Science & Technology

2013-08-01

cost due to potential warranty costs, repairs and loss of market share. Reliability is the probability that the system will perform its intended...MCMC and splitting sampling schemes. Our proposed SS/ STP method is presented in Section 4, including accuracy bounds and computational effort

Lithographically Patterned Nanoscale Electrodeposition of Plasmonic, Bimetallic, Semiconductor, Magnetic, and Polymer Nanoring Arrays

PubMed Central

2015-01-01

Large area arrays of magnetic, semiconducting, and insulating nanorings were created by coupling colloidal lithography with nanoscale electrodeposition. This versatile nanoscale fabrication process allows for the independent tuning of the spacing, diameter, and width of the nanorings with typical values of 1.0 μm, 750 nm, and 100 nm, respectively, and was used to form nanorings from a host of materials: Ni, Co, bimetallic Ni/Au, CdSe, and polydopamine. These nanoring arrays have potential applications in memory storage, optical materials, and biosensing. A modified version of this nanoscale electrodeposition process was also used to create arrays of split gold nanorings. The size of the split nanoring opening was controlled by the angle of photoresist exposure during the fabrication process and could be varied from 50% down to 10% of the ring circumference. The large area (cm2 scale) gold split nanoring array surfaces exhibited strong polarization-dependent plasmonic absorption bands for wavelengths from 1 to 5 μm. Plasmonic nanoscale split ring arrays are potentially useful as tunable dichroic materials throughout the infrared and near-infrared spectral regions. PMID:25553204

World Trade Center human identification project: experiences with individual body identification cases.

PubMed

Budimlija, Zoran M; Prinz, Mechthild K; Zelson-Mundorff, Amy; Wiersema, Jason; Bartelink, Eric; MacKinnon, Gaille; Nazzaruolo, Bianca L; Estacio, Sheila M; Hennessey, Michael J; Shaler, Robert C

2003-06-01

To present individual body identification efforts, as part of the World Trade Center (WTC) mass disaster identification project. More than 500 samples were tested by using polymerase chain reaction (PCR) amplification and short tandem repeat (STR) typing. The extent to which the remains were fragmented and affected by taphonomic factors complicated the identification project. Anthropologists reviewed 19,000 samples, and detected inconsistencies in 69, which were further split into 239 new cases and re-sampled by DNA specialists. The severity and nature of the disaster required an interdisciplinary effort. DNA profiling of 500 samples was successful in 75% of the cases. All discrepancies, which occurred between bone and tissue samples taken from the same body part, were resolved by re-sampling and re-testing of preferably bone tissue. Anthropologists detected inconsistencies in 69 cases, which were then split into 239 new cases. Out of 125 "split" cases, 65 were excluded from their original case. Of these 65 cases, 37 did not match any profiles in M-FISys, probably because profiles were incomplete or no exemplar for the victim was available. Out of the 60 remains not excluded from their original case, 30 were partial profiles and did not reach the statistical requirement to match their original case, because the population frequency of the DNA profile had to be

Splitting algorithm for numerical simulation of Li-ion battery electrochemical processes

NASA Astrophysics Data System (ADS)

Iliev, Oleg; Nikiforova, Marina A.; Semenov, Yuri V.; Zakharov, Petr E.

2017-11-01

In this paper we present a splitting algorithm for a numerical simulation of Li-ion battery electrochemical processes. Liion battery consists of three domains: anode, cathode and electrolyte. Mathematical model of electrochemical processes is described on a microscopic scale, and contains nonlinear equations for concentration and potential in each domain. On the interface of electrodes and electrolyte there are the Lithium ions intercalation and deintercalation processes, which are described by Butler-Volmer nonlinear equation. To approximate in spatial coordinates we use finite element methods with discontinues Galerkin elements. To simplify numerical simulations we develop the splitting algorithm, which split the original problem into three independent subproblems. We investigate the numerical convergence of the algorithm on 2D model problem.

Submicron Systems Architecture

DTIC Science & Technology

1983-11-01

hours, and is producing successively more and more refined statistics . It will run for several hundred more hours before improving significantly on the...splitting a node into two parts and connecting to. Similarly, a stuck-open transitor falt ishr t n whi modeled by putting a fault transistor in series

Data splitting for artificial neural networks using SOM-based stratified sampling.

PubMed

May, R J; Maier, H R; Dandy, G C

2010-03-01

Data splitting is an important consideration during artificial neural network (ANN) development where hold-out cross-validation is commonly employed to ensure generalization. Even for a moderate sample size, the sampling methodology used for data splitting can have a significant effect on the quality of the subsets used for training, testing and validating an ANN. Poor data splitting can result in inaccurate and highly variable model performance; however, the choice of sampling methodology is rarely given due consideration by ANN modellers. Increased confidence in the sampling is of paramount importance, since the hold-out sampling is generally performed only once during ANN development. This paper considers the variability in the quality of subsets that are obtained using different data splitting approaches. A novel approach to stratified sampling, based on Neyman sampling of the self-organizing map (SOM), is developed, with several guidelines identified for setting the SOM size and sample allocation in order to minimize the bias and variance in the datasets. Using an example ANN function approximation task, the SOM-based approach is evaluated in comparison to random sampling, DUPLEX, systematic stratified sampling, and trial-and-error sampling to minimize the statistical differences between data sets. Of these approaches, DUPLEX is found to provide benchmark performance with good model performance, with no variability. The results show that the SOM-based approach also reliably generates high-quality samples and can therefore be used with greater confidence than other approaches, especially in the case of non-uniform datasets, with the benefit of scalability to perform data splitting on large datasets. Copyright 2009 Elsevier Ltd. All rights reserved.

Association between split selection instability and predictive error in survival trees.

PubMed

Radespiel-Tröger, M; Gefeller, O; Rabenstein, T; Hothorn, T

2006-01-01

To evaluate split selection instability in six survival tree algorithms and its relationship with predictive error by means of a bootstrap study. We study the following algorithms: logrank statistic with multivariate p-value adjustment without pruning (LR), Kaplan-Meier distance of survival curves (KM), martingale residuals (MR), Poisson regression for censored data (PR), within-node impurity (WI), and exponential log-likelihood loss (XL). With the exception of LR, initial trees are pruned by using split-complexity, and final trees are selected by means of cross-validation. We employ a real dataset from a clinical study of patients with gallbladder stones. The predictive error is evaluated using the integrated Brier score for censored data. The relationship between split selection instability and predictive error is evaluated by means of box-percentile plots, covariate and cutpoint selection entropy, and cutpoint selection coefficients of variation, respectively, in the root node. We found a positive association between covariate selection instability and predictive error in the root node. LR yields the lowest predictive error, while KM and MR yield the highest predictive error. The predictive error of survival trees is related to split selection instability. Based on the low predictive error of LR, we recommend the use of this algorithm for the construction of survival trees. Unpruned survival trees with multivariate p-value adjustment can perform equally well compared to pruned trees. The analysis of split selection instability can be used to communicate the results of tree-based analyses to clinicians and to support the application of survival trees.

Tablet splitting of a narrow therapeutic index drug: a case with levothyroxine sodium.

PubMed

Shah, Rakhi B; Collier, Jarrod S; Sayeed, Vilayat A; Bryant, Arthur; Habib, Muhammad J; Khan, Mansoor A

2010-09-01

Levothyroxine is a narrow therapeutic index, and to avoid adverse effect associated with under or excessive dosage, the dose response is carefully titrated. The tablets are marketed with a score providing an option to split. However, there are no systematic studies evaluating the effect of splitting on dose accuracy, and current study was undertaken to evaluate effects of splitting and potential causes for uniformity failures by measuring assay and content uniformity in whole and split tablets. Stability was evaluated by assaying drug for a period of 8 weeks. Effect of formulation factors on splittability was evaluated by a systematic investigation of formulation factors by preparing levothyroxine tablets in house by varying the type of excipients (binder, diluent, disintegrant, glidant) or by varying the processing factors (granulating liquid, mixing type, compression pressure). The tablets were analyzed using novel analytical tool such as near infrared chemical imaging to visualize the distribution of levothyroxine. Assay was not significantly different for whole versus split tablets irrespective of method of splitting (hand or splitter), and splitting also had no measurable impact on the stability. Split tablets either by hand or splitter showed higher rate of content uniformity failures as compared to whole tablets. Tablet splitter produced more fragmentation and, hence, more content uniformity and friability failures. Chemical imaging data revealed that the distribution of levothyroxine was heterogeneous and was dependent on type of binder and the process used in the manufacture of tablets. Splitting such tablets could prove detrimental if sub- or super-potency becomes an issue.

Showcasing electrode-electrolyte interfacial potential as a vital parameter in the hydrogen generation by metal oxides electrodes

NASA Astrophysics Data System (ADS)

Niveditha, C. V.; Nizamudeen, A. C.; Ramanarayanan, Rajita; Jabeen Fatima, M. J.; Swaminathan, Sindhu

2018-03-01

This investigation presents a new insight by experimentally demonstrating electrode-electrolyte interface potential that is flat band potential as a determinant in photoelectrochemical splitting of water. Two different metal oxides namely n type, nitrogen doped titania and p type copper oxides have been synthesized for the study. The flat band potential values of these oxide systems were obtained from Mott-Schottky analysis. The obtained flat band potential is used as a marker to fix the working potential in water splitting experiment. To obtain optimum photocurrent a potential more positive than flatband is applied to n-type N-TiO2 and vice-versa for p-type Cu2O. The findings are well supported by I-t curves derived from chronoamperometric measurements. Finally the mechanisms behind interfacial potential dynamics have been discussed in this work.

Multimedia Presentations of Mitosis: An Examination of Split-Attention, Modality, Redundancy, and Cueing

ERIC Educational Resources Information Center

Cook, Michelle; Visser, Ryan

2014-01-01

Multimedia presentations that combine visual and verbal information are widely used for instructional purposes. While the design of the text-graphic relationship is difficult, several design strategies with the potential to reduce cognitive load have been identified in the literature. The purpose of this study is to examine how split-attention,…

Right Hemisphere Dominance in Visual Statistical Learning

ERIC Educational Resources Information Center

Roser, Matthew E.; Fiser, Jozsef; Aslin, Richard N.; Gazzaniga, Michael S.

2011-01-01

Several studies report a right hemisphere advantage for visuospatial integration and a left hemisphere advantage for inferring conceptual knowledge from patterns of covariation. The present study examined hemispheric asymmetry in the implicit learning of new visual feature combinations. A split-brain patient and normal control participants viewed…

The vibration-rotation-tunneling levels of N2-H2O and N2-D2O.

PubMed

Wang, Xiao-Gang; Carrington, Tucker

2015-07-14

In this paper, we report vibration-rotation-tunneling levels of the van der Waals clusters N2-H2O and N2-D2O computed from an ab initio potential energy surface. The only dynamical approximation is that the monomers are rigid. We use a symmetry adapted Lanczos algorithm and an uncoupled product basis set. The pattern of the cluster's levels is complicated by splittings caused by H-H exchange tunneling (larger splitting) and N-N exchange tunneling (smaller splitting). An interesting result that emerges from our calculation is that whereas in N2-H2O, the symmetric H-H tunnelling state is below the anti-symmetric H-H tunnelling state for both K = 0 and K = 1, the order is reversed in N2-D2O for K = 1. The only experimental splitting measurements are the D-D exchange tunneling splittings reported by Zhu et al. [J. Chem. Phys. 139, 214309 (2013)] for N2-D2O in the v2 = 1 region of D2O. Due to the inverted order of the split levels, they measure the sum of the K = 0 and K = 1 tunneling splittings, which is in excellent agreement with our calculated result. Other splittings we predict, in particular those of N2-H2O, may guide future experiments.

The vibration-rotation-tunneling levels of N2-H2O and N2-D2O

NASA Astrophysics Data System (ADS)

Wang, Xiao-Gang; Carrington, Tucker

2015-07-01

In this paper, we report vibration-rotation-tunneling levels of the van der Waals clusters N2-H2O and N2-D2O computed from an ab initio potential energy surface. The only dynamical approximation is that the monomers are rigid. We use a symmetry adapted Lanczos algorithm and an uncoupled product basis set. The pattern of the cluster's levels is complicated by splittings caused by H-H exchange tunneling (larger splitting) and N-N exchange tunneling (smaller splitting). An interesting result that emerges from our calculation is that whereas in N2-H2O, the symmetric H-H tunnelling state is below the anti-symmetric H-H tunnelling state for both K = 0 and K = 1, the order is reversed in N2-D2O for K = 1. The only experimental splitting measurements are the D-D exchange tunneling splittings reported by Zhu et al. [J. Chem. Phys. 139, 214309 (2013)] for N2-D2O in the v2 = 1 region of D2O. Due to the inverted order of the split levels, they measure the sum of the K = 0 and K = 1 tunneling splittings, which is in excellent agreement with our calculated result. Other splittings we predict, in particular those of N2-H2O, may guide future experiments.

Examination of two methods for statistical analysis of data with magnitude and direction emphasizing vestibular research applications

NASA Technical Reports Server (NTRS)

Calkins, D. S.

1998-01-01

When the dependent (or response) variable response variable in an experiment has direction and magnitude, one approach that has been used for statistical analysis involves splitting magnitude and direction and applying univariate statistical techniques to the components. However, such treatment of quantities with direction and magnitude is not justifiable mathematically and can lead to incorrect conclusions about relationships among variables and, as a result, to flawed interpretations. This note discusses a problem with that practice and recommends mathematically correct procedures to be used with dependent variables that have direction and magnitude for 1) computation of mean values, 2) statistical contrasts of and confidence intervals for means, and 3) correlation methods.

Rashba-type spin splitting and the electronic structure of ultrathin Pb/MoTe2 heterostructure

NASA Astrophysics Data System (ADS)

Du, X.; Wang, Z. Y.; Huang, G. Q.

2016-11-01

The spin-polarized band structures of the Pb(111)/MoTe2 heterostructure are studied by the first-principles calculations. Due to strong spin-orbit coupling and space inversion asymmetry, large Rashba spin splitting of electronic bands appears in this hybrid system. The spin splitting is completely out-of-plane and opposite at \\bar{K} and {\\bar{K}}\\prime points. Rashba spin splitting also appears along the in-plane momentum direction around the \\bar{{{Γ }}} point due to the existence of surface potential gradient induced by charge transfer at interface. Furthermore, our calculations show that the spin-polarized bands closely approach the Fermi level in Pb/MoTe2 heterostructure, showing that this heterostructure may be a good candidate in valleytronics or spintronics.

Fermion localization on a split brane

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

Chumbes, A. E. R.; Vasquez, A. E. O.; Hott, M. B.

2011-05-15

In this work we analyze the localization of fermions on a brane embedded in five-dimensional, warped and nonwarped, space-time. In both cases we use the same nonlinear theoretical model with a nonpolynomial potential featuring a self-interacting scalar field whose minimum energy solution is a soliton (a kink) which can be continuously deformed into a two-kink. Thus a single brane splits into two branes. The behavior of spin 1/2 fermions wave functions on the split brane depends on the coupling of fermions to the scalar field and on the geometry of the space-time.

Reversible Hydrophobic to Hydrophilic Transition in Graphene via Water Splitting Induced by UV Irradiation

PubMed Central

Xu, Zhemi; Ao, Zhimin; Chu, Dewei; Younis, Adnan; Li, Chang Ming; Li, Sean

2014-01-01

Although the reversible wettability transition between hydrophobic and hydrophilic graphene under ultraviolet (UV) irradiation has been observed, the mechanism for this phenomenon remains unclear. In this work, experimental and theoretical investigations demonstrate that the H2O molecules are split into hydrogen and hydroxyl radicals, which are then captured by the graphene surface through chemical binding in an ambient environment under UV irradiation. The dissociative adsorption of H2O molecules induces the wettability transition in graphene from hydrophobic to hydrophilic. Our discovery may hold promise for the potential application of graphene in water splitting. PMID:25245110

A Comparison of Conjoint Analysis Response Formats

Treesearch

Kevin J. Boyle; Thomas P. Holmes; Mario F. Teisl; Brian Roe

2001-01-01

A split-sample design is used to evaluate the convergent validity of three response formats used in conjoint analysis experiments. WC investigate whether recoding rating data to rankings and choose-one formats, and recoding ranking data to choose one. result in structural models and welfare estimates that are statistically indistinguishable from...

Silicon Nitride for Direct Water-Splitting and Corrosion Mitigation

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

Head, J.; Turner, J.A.

2006-01-01

Todays fossil fuels are becoming harder to obtain, creating pollution problems, and posing hazards to people’s health. One alternative to fossil fuels is hydrogen, capable of serving as a clean and efficient energy carrier. Certain semiconductors are able to harness the energy of photons and direct it into water electrolysis in a process known as photoelectrochemical water splitting. Triple junction devices integrate three semiconductors of different band gaps resulting in a monolithic material that absorbs over a broader spectrum. Amorphous silicon (a-Si) is one such material that, when stacked in tandem, possesses water-splitting capabilities. Even though a-Si is capable ofmore » splitting water, it is an unstable material in solution and therefore requires a coating to protect the surface from corrosion. A stable, transparent material that has the potential for corrosion protection is silicon nitride. In this study, silicon nitride thin films were grown using DC magnetron sputtering with varying amounts of argon and nitrogen added to the system. X-ray diffraction indicated amorphous silicon nitride films. Current as a function of potential was determined from cyclic voltammetry measurements. Mott-Schottky analysis showed n-type behavior with absorption and transmission measurements indicated variation in flatband potentials. Variation in band gap values ranging from 1.90 to 4.0 eV. Corrosion measurements reveal that the silicon nitride samples exhibit both p-type and n-type behavior. Photocurrent over a range of potentials was greater in samples that were submerged in acidic electrolyte. Silicon nitride shows good stability in acidic, neutral, and basic solutions, indicative of a good material for corrosion mitigation.« less

Towards ultrafast dynamics with split-pulse X-ray photon correlation spectroscopy at free electron laser sources

DOE PAGES

Roseker, W.; Hruszkewycz, S. O.; Lehmkuhler, F.; ...

2018-04-27

One of the important challenges in condensed matter science is to understand ultrafast, atomic-scale fluctuations that dictate dynamic processes in equilibrium and non-equilibrium materials. Here, we report an important step towards reaching that goal by using a state-of-the-art perfect crystal based split-and-delay system, capable of splitting individual X-ray pulses and introducing femtosecond to nanosecond time delays. We show the results of an ultrafast hard X-ray photon correlation spectroscopy experiment at LCLS where split X-ray pulses were used to measure the dynamics of gold nanoparticles suspended in hexane. We show how reliable speckle contrast values can be extracted even from verymore » low intensity free electron laser (FEL) speckle patterns by applying maximum likelihood fitting, thus demonstrating the potential of a split-and-delay approach for dynamics measurements at FEL sources. This will enable the characterization of equilibrium and, importantly also reversible non-equilibrium processes in atomically disordered materials.« less

Towards ultrafast dynamics with split-pulse X-ray photon correlation spectroscopy at free electron laser sources

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

Roseker, W.; Hruszkewycz, S. O.; Lehmkuhler, F.

One of the important challenges in condensed matter science is to understand ultrafast, atomic-scale fluctuations that dictate dynamic processes in equilibrium and non-equilibrium materials. Here, we report an important step towards reaching that goal by using a state-of-the-art perfect crystal based split-and-delay system, capable of splitting individual X-ray pulses and introducing femtosecond to nanosecond time delays. We show the results of an ultrafast hard X-ray photon correlation spectroscopy experiment at LCLS where split X-ray pulses were used to measure the dynamics of gold nanoparticles suspended in hexane. We show how reliable speckle contrast values can be extracted even from verymore » low intensity free electron laser (FEL) speckle patterns by applying maximum likelihood fitting, thus demonstrating the potential of a split-and-delay approach for dynamics measurements at FEL sources. This will enable the characterization of equilibrium and, importantly also reversible non-equilibrium processes in atomically disordered materials.« less

Layer Splitting in a Complex Plasma

NASA Astrophysics Data System (ADS)

Smith, Bernard; Hyde, Truell; Matthews, Lorin; Johnson, Megan; Cook, Mike; Schmoke, Jimmy

2009-11-01

Dust particle clouds are found in most plasma processing environments and many astrophysical environments. Dust particles suspended within such plasmas often acquire an electric charge from collisions with free electrons in the plasma. Depending upon the ratio of interparticle potential energy to average kinetic energy, charged dust particles can form a gaseous, liquid or crystalline structure with short to longer range ordering. An interesting facet of complex plasma behavior is that particle layers appear to split as the DC bias is increased. This splitting of layers points to a phase transition differing from the normal phase transitions found in two-dimensional solids. In 1993, Dubin noted that as the charged particle density of an initially two-dimensional Coulomb crystal increases the system's layers split at specific charge densities. This work modeled ions in a Paul or Penning trap, but may be applicable to dusty plasma systems as well. This work will discuss this possibility along with splitting observed in the CASPER GEC rf Reference Cell at specific pressures and powers.

Spatial mapping and statistical reproducibility of an array of 256 one-dimensional quantum wires

NASA Astrophysics Data System (ADS)

Al-Taie, H.; Smith, L. W.; Lesage, A. A. J.; See, P.; Griffiths, J. P.; Beere, H. E.; Jones, G. A. C.; Ritchie, D. A.; Kelly, M. J.; Smith, C. G.

2015-08-01

We utilize a multiplexing architecture to measure the conductance properties of an array of 256 split gates. We investigate the reproducibility of the pinch off and one-dimensional definition voltage as a function of spatial location on two different cooldowns, and after illuminating the device. The reproducibility of both these properties on the two cooldowns is high, the result of the density of the two-dimensional electron gas returning to a similar state after thermal cycling. The spatial variation of the pinch-off voltage reduces after illumination; however, the variation of the one-dimensional definition voltage increases due to an anomalous feature in the center of the array. A technique which quantifies the homogeneity of split-gate properties across the array is developed which captures the experimentally observed trends. In addition, the one-dimensional definition voltage is used to probe the density of the wafer at each split gate in the array on a micron scale using a capacitive model.

Use of fibrinogen and thrombin sponge in pediatric split liver transplantation.

PubMed

Vicentine, Fernando Pompeu Piza; Gonzalez, Adriano Miziara; Beninni, Barbara Burza; Azevedo, Ramiro Anthero de; Linhares, Marcelo Moura; Goldenberg, Alberto; Lopes, Gaspar de Jesus; Martins, Jose Luiz; Salzedas, Alcides Augusto

2017-08-01

To analyze the use of this sponge in pediatric patients undergoing split-liver transplantation. Retrospective study, including 35 pediatric patients undergoing split-liver transplantation, divided into two groups according to the use of the sponge: 18 patients in Group A (no sponge) and 17 in Group B (with sponge). The characteristics of recipients and donors were similar. We observed greater number of reoperation due to bleeding in the wound area in Group A (10 patients - 55.5%) than in Group B (3 patients - 17.6%); p = 0.035. The median volume of red blood cells transfused in Group A was significantly higher (73.4 ± 102.38 mL/kg) than that in Group B (35.1 ± 41.67 mL/kg); p = 0.048. Regarding bile leak there was no statistical difference. The use of the human fibrinogen and thrombin sponge, required lower volume of red blood cell transfusion and presented lower reoperation rates due to bleeding in the wound area.

Quasi-chemical theory of F-(aq): The "no split occupancies rule" revisited

NASA Astrophysics Data System (ADS)

Chaudhari, Mangesh I.; Rempe, Susan B.; Pratt, Lawrence R.

2017-10-01

We use ab initio molecular dynamics (AIMD) calculations and quasi-chemical theory (QCT) to study the inner-shell structure of F-(aq) and to evaluate that single-ion free energy under standard conditions. Following the "no split occupancies" rule, QCT calculations yield a free energy value of -101 kcal/mol under these conditions, in encouraging agreement with tabulated values (-111 kcal/mol). The AIMD calculations served only to guide the definition of an effective inner-shell constraint. QCT naturally includes quantum mechanical effects that can be concerning in more primitive calculations, including electronic polarizability and induction, electron density transfer, electron correlation, molecular/atomic cooperative interactions generally, molecular flexibility, and zero-point motion. No direct assessment of the contribution of dispersion contributions to the internal energies has been attempted here, however. We anticipate that other aqueous halide ions might be treated successfully with QCT, provided that the structure of the underlying statistical mechanical theory is absorbed, i.e., that the "no split occupancies" rule is recognized.

Landau level splitting due to graphene superlattices

NASA Astrophysics Data System (ADS)

Pal, G.; Apel, W.; Schweitzer, L.

2012-06-01

The Landau level spectrum of graphene superlattices is studied using a tight-binding approach. We consider noninteracting particles moving on a hexagonal lattice with an additional one-dimensional superlattice made up of periodic square potential barriers, which are oriented along the zigzag or along the armchair directions of graphene. In the presence of a perpendicular magnetic field, such systems can be described by a set of one-dimensional tight-binding equations, the Harper equations. The qualitative behavior of the energy spectrum with respect to the strength of the superlattice potential depends on the relation between the superlattice period and the magnetic length. When the potential barriers are oriented along the armchair direction of graphene, we find for strong magnetic fields that the zeroth Landau level of graphene splits into two well-separated sublevels, if the width of the barriers is smaller than the magnetic length. In this situation, which persists even in the presence of disorder, a plateau with zero Hall conductivity can be observed around the Dirac point. This Landau level splitting is a true lattice effect that cannot be obtained from the generally used continuum Dirac-fermion model.

Oxygen consumption, oxygen cost, heart rate, and perceived effort during split-belt treadmill walking in young healthy adults.

PubMed

Roper, Jaimie A; Stegemöller, Elizabeth L; Tillman, Mark D; Hass, Chris J

2013-03-01

During split-belt treadmill walking the speed of the treadmill under one limb is faster than the belt under the contralateral limb. This unique intervention has shown evidence of acutely improving gait impairments in individuals with neurologic impairment such as stroke and Parkinson's disease. However, oxygen use, heart rate and perceived effort associated with split-belt treadmill walking are unknown and may limit the utility of this locomotor intervention. To better understand the intensity of this new intervention, this study was undertaken to examine the oxygen consumption, oxygen cost, heart rate, and rating of perceived exertion associated with split-belt treadmill walking in young healthy adults. Fifteen participants completed three sessions of treadmill walking: slow speed with belts tied, fast speed with belts tied, and split-belt walking with one leg walking at the fast speed and one leg walking at the slow speed. Oxygen consumption, heart rate, and rating of perceived exertion were collected during each walking condition and oxygen cost was calculated. Results revealed that oxygen consumption, heart rate, and perceived effort associated with split-belt walking were higher than slow treadmill walking, but only oxygen consumption was significantly lower during both split-belt walking than fast treadmill walking. Oxygen cost associated with slow treadmill walking was significantly higher than fast treadmill walking. These findings have implications for using split-belt treadmill walking as a rehabilitation tool as the cost associated with split-belt treadmill walking may not be higher or potentially more detrimental than that associated with previously used treadmill training rehabilitation strategies.

Can short-term oral fine motor training affect precision of task performance and induce cortical plasticity of the jaw muscles?

PubMed

Zhang, Hong; Kumar, Abhishek; Kothari, Mohit; Luo, Xiaoping; Trulsson, Mats; Svensson, Krister G; Svensson, Peter

2016-07-01

The aim was to test the hypothesis that short-term oral sensorimotor training of the jaw muscles would increase the precision of task performance and induce neuroplastic changes in the corticomotor pathways, related to the masseter muscle. Fifteen healthy volunteers performed six series with ten trials of an oral sensorimotor task. The task was to manipulate and position a spherical chocolate candy in between the anterior teeth and split it into two equal halves. The precision of the task performance was evaluated by comparing the ratio between the two split halves. A series of "hold-and-split" tasks was also performed before and after the training. The hold force and split force along with the electromyographic (EMG) activity of jaw muscles were recorded. Motor-evoked potentials and cortical motor maps of the right masseter muscle were evoked by transcranial magnetic stimulation. There was a significant effect of series on the precision of the task performance during the short-term oral sensorimotor training (P < 0.002). The hold force during the "hold-and-split" task was significantly lower after training than before the short-term training (P = 0.011). However, there was no change in the split force and the EMG activity of the jaw muscles before and after the training. Further, there was a significant increase in the amplitude of the motor-evoked potentials (P < 0.016) and in the motor cortex map areas (P = 0.033), after the short-term oral sensorimotor training. Therefore, short-term oral sensorimotor task training increased the precision of task performance and induced signs of neuroplastic changes in the corticomotor pathways, related to the masseter muscle.

Non-Gaussian bias: insights from discrete density peaks

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

Desjacques, Vincent; Riotto, Antonio; Gong, Jinn-Ouk, E-mail: Vincent.Desjacques@unige.ch, E-mail: jinn-ouk.gong@apctp.org, E-mail: Antonio.Riotto@unige.ch

2013-09-01

Corrections induced by primordial non-Gaussianity to the linear halo bias can be computed from a peak-background split or the widespread local bias model. However, numerical simulations clearly support the prediction of the former, in which the non-Gaussian amplitude is proportional to the linear halo bias. To understand better the reasons behind the failure of standard Lagrangian local bias, in which the halo overdensity is a function of the local mass overdensity only, we explore the effect of a primordial bispectrum on the 2-point correlation of discrete density peaks. We show that the effective local bias expansion to peak clustering vastlymore » simplifies the calculation. We generalize this approach to excursion set peaks and demonstrate that the resulting non-Gaussian amplitude, which is a weighted sum of quadratic bias factors, precisely agrees with the peak-background split expectation, which is a logarithmic derivative of the halo mass function with respect to the normalisation amplitude. We point out that statistics of thresholded regions can be computed using the same formalism. Our results suggest that halo clustering statistics can be modelled consistently (in the sense that the Gaussian and non-Gaussian bias factors agree with peak-background split expectations) from a Lagrangian bias relation only if the latter is specified as a set of constraints imposed on the linear density field. This is clearly not the case of standard Lagrangian local bias. Therefore, one is led to consider additional variables beyond the local mass overdensity.« less

Probing individual tunneling fluctuators with coherently controlled tunneling systems

NASA Astrophysics Data System (ADS)

Meißner, Saskia M.; Seiler, Arnold; Lisenfeld, Jürgen; Ustinov, Alexey V.; Weiss, Georg

2018-05-01

Josephson junctions made from aluminum and its oxide are the most commonly used functional elements for superconducting circuits and qubits. It is generally known that the disordered thin film AlOx contains atomic tunneling systems. Coherent tunneling systems may couple strongly to a qubit via their electric dipole moment, giving rise to spectral level repulsion. In addition, slowly fluctuating tunneling systems are observable when they are located close to coherent ones and distort their potentials. This interaction causes telegraphic switching of the coherent tunneling systems' energy splitting. Here, we measure such switching induced by individual fluctuators on timescales from hours to minutes using a superconducting qubit as a detector. Moreover, we extend the range of measurable switching times to millisecond scales by employing a highly sensitive single-photon qubit swap spectroscopy and statistical analysis of the measured qubit states.

Split-wedge antennas with sub-5 nm gaps for plasmonic nanofocusing

DOE PAGES

Chen, Xiaoshu; Lindquist, Nathan C.; Klemme, Daniel J.; ...

2016-11-22

Here, we present a novel plasmonic antenna structure, a split-wedge antenna, created by splitting an ultrasharp metallic wedge with a nanogap perpendicular to its apex. The nanogap can tightly confine gap plasmons and boost the local optical field intensity in and around these opposing metallic wedge tips. This three-dimensional split-wedge antenna integrates the key features of nanogaps and sharp tips, i.e., tight field confinement and three-dimensional nanofocusing, respectively, into a single platform. We fabricate split-wedge antennas with gaps that are as small as 1 nm in width at the wafer scale by combining silicon V-grooves with template stripping and atomicmore » layer lithography. Computer simulations show that the field enhancement and confinement are stronger at the tip–gap interface compared to what standalone tips or nanogaps produce, with electric field amplitude enhancement factors exceeding 50 when near-infrared light is focused on the tip–gap geometry. The resulting nanometric hotspot volume is on the order of λ 3/10 6. Experimentally, Raman enhancement factors exceeding 10 7 are observed from a 2 nm gap split-wedge antenna, demonstrating its potential for sensing and spectroscopy applications.« less

The practice and clinical implications of tablet splitting in international health

PubMed Central

Elliott, Ivo; Mayxay, Mayfong; Yeuichaixong, Sengchanh; Lee, Sue J; Newton, Paul N

2014-01-01

Objective Tablet splitting is frequently performed to facilitate correct dosing, but the practice and implications in low-income settings have rarely been discussed. Methods We selected eight drugs, with narrow therapeutic indices or critical dosages, frequently divided in the Lao PDR (Laos). These were split, by common techniques used in Laos, by four nurses and four laypersons. The mean percentage deviation from the theoretical expected weight and weight loss of divided tablets/capsules were recorded. Results Five of eight study drugs failed, on splitting, to meet European Pharmacopoeia recommendations for tablet weight deviation from the expected weight of tablet/capsule halves with 10% deviating by more than 25%. There was a significant difference in splitting accuracy between nurses and laypersons (P = 0.027). Coated and unscored tablets were less accurately split than uncoated (P = 0.03 and 0.0019 for each half) and scored (0.0001 for both halves) tablets. Conclusion These findings have potential clinical implications on treatment outcome and the development of antimicrobial resistance. Investment by drug companies in a wider range of dosage units, particularly for narrow therapeutic index and critical dosage medicines, is strongly recommended. PMID:24702766

Conservative supra-characteristics method for splitting the hyperbolic systems of gasdynamics for real and perfect gases

NASA Technical Reports Server (NTRS)

Lombard, C. K.

1982-01-01

A conservative flux difference splitting is presented for the hyperbolic systems of gasdynamics. The stable robust method is suitable for wide application in a variety of schemes, explicit or implicit, iterative or direct, for marching in either time or space. The splitting is modeled on the local quasi one dimensional characteristics system for multi-dimensional flow similar to Chakravarthy's nonconservative split coefficient matrix method; but, as the result of maintaining global conservation, the method is able to capture sharp shocks correctly. The embedded characteristics formulation is cast in a primitive variable the volumetric internal energy (rather than the pressure) that is effective for treating real as well as perfect gases. Finally the relationship of the splitting to characteristics boundary conditions is discussed and the associated conservative matrix formulation for a computed blown wall boundary condition is developed as an example. The theoretical development employs and extends the notion of Roe of constructing stable upwind difference formulae by sending split simple one sided flux difference pieces to appropriate mesh sites. The developments are also believed to have the potential for aiding in the analysis of both existing and new conservative difference schemes.

Split-Wedge Antennas with Sub-5 nm Gaps for Plasmonic Nanofocusing

PubMed Central

2016-01-01

We present a novel plasmonic antenna structure, a split-wedge antenna, created by splitting an ultrasharp metallic wedge with a nanogap perpendicular to its apex. The nanogap can tightly confine gap plasmons and boost the local optical field intensity in and around these opposing metallic wedge tips. This three-dimensional split-wedge antenna integrates the key features of nanogaps and sharp tips, i.e., tight field confinement and three-dimensional nanofocusing, respectively, into a single platform. We fabricate split-wedge antennas with gaps that are as small as 1 nm in width at the wafer scale by combining silicon V-grooves with template stripping and atomic layer lithography. Computer simulations show that the field enhancement and confinement are stronger at the tip–gap interface compared to what standalone tips or nanogaps produce, with electric field amplitude enhancement factors exceeding 50 when near-infrared light is focused on the tip–gap geometry. The resulting nanometric hotspot volume is on the order of λ3/106. Experimentally, Raman enhancement factors exceeding 107 are observed from a 2 nm gap split-wedge antenna, demonstrating its potential for sensing and spectroscopy applications. PMID:27960527

Substituent effects on photosensitized splitting of thymine cyclobutane dimer by an attached indole.

PubMed

Tang, Wenjian; Zhou, Hongmei; Wang, Jing; Pan, Chunxiao; Shi, Jingbo; Song, Qinhua

2012-12-21

In chromophore-containing cyclobutane pyrimidine dimer (CPD) model systems, solvent effects on the splitting efficiency may depend on the length of the linker, the molecular conformation, and the oxidation potential of the donor. To further explore the relationship between chromophore structure and splitting efficiency, we prepared a series of substituted indole-T< >T model compounds 2 a-2 g and measured their splitting quantum yields in various solvents. Two reverse solvent effects were observed: an increase in splitting efficiency in solvents of lower polarity for models 2 a-2 d with an electron-donating group (EDG), and vice versa for models 2 e-2 g with an electron-withdrawing group (EWG). According to the Hammett equation, the negative value of the slope of the Hammett plot indicates that the indole moiety during the T< >T-splitting reaction loses negative charge, and the larger negative value implies that the repair reaction is more sensitive to substituent effects in low-polarity solvents. The EDGs of the models 2 a-2 d can delocalize the charge-separated state, and low-polarity solvents make it more stable, which leads to higher splitting efficiency in low-polarity solvents. Conversely, the EWGs of models 2 e-2 g favor destabilization of the charge-separated state, and high-polarity solvents decrease the destabilization and hence lead to more efficient splitting in high-polarity solvents. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

One‐dimensional TiO2 Nanotube Photocatalysts for Solar Water Splitting

PubMed Central

Ge, Mingzheng; Li, Qingsong; Cao, Chunyan; Huang, Jianying; Li, Shuhui; Zhang, Songnan; Chen, Zhong; Zhang, Keqin; Al‐Deyab, Salem S.

2016-01-01

Hydrogen production from water splitting by photo/photoelectron‐catalytic process is a promising route to solve both fossil fuel depletion and environmental pollution at the same time. Titanium dioxide (TiO2) nanotubes have attracted much interest due to their large specific surface area and highly ordered structure, which has led to promising potential applications in photocatalytic degradation, photoreduction of CO2, water splitting, supercapacitors, dye‐sensitized solar cells, lithium‐ion batteries and biomedical devices. Nanotubes can be fabricated via facile hydrothermal method, solvothermal method, template technique and electrochemical anodic oxidation. In this report, we provide a comprehensive review on recent progress of the synthesis and modification of TiO2 nanotubes to be used for photo/photoelectro‐catalytic water splitting. The future development of TiO2 nanotubes is also discussed. PMID:28105391

A review on g-C3N4 for photocatalytic water splitting and CO2 reduction

NASA Astrophysics Data System (ADS)

Ye, Sheng; Wang, Rong; Wu, Ming-Zai; Yuan, Yu-Peng

2015-12-01

Solar fuel generation through water splitting and CO2 photoreduction is an ideal route to provide the renewable energy sources and mitigate global warming. The main challenge in photocatalysis is finding a low-cost photocatalyst that can work efficiently to split water into hydrogen and reduce CO2 to hydrocarbon fuels. Metal-free g-C3N4 photocatalyst shows great potentials for solar fuel production. In this mini review, we summarize the most current advances on novel design idea and new synthesis strategy for g-C3N4 preparation, insightful ideas on extending optical absorption of pristine g-C3N4, overall water splitting and CO2 photoreduction over g-C3N4 based systems. The research challenges and perspectives on g-C3N4 based photocatalysts were also suggested.

Effects of soil moisture depletion on vegetable crop uptake of pharmaceuticals and personal care products (PPCPs).

PubMed

Santiago, Sergio; Roll, Deborah M; Ray, Chittaranjan; Williams, Clinton; Moravcik, Philip; Knopf, Allan

2016-10-01

Agricultural crops have a long history of being irrigated with recycled wastewater (RW). However, its use on vegetable crops has been of concern due to the potential prevalence of microcontaminants, such as pharmaceuticals and personal care products (PPCPs) in the latter, which represents a possible health hazard to consumers. We investigated the uptake of three PPCPs (atenolol, diclofenac, and ofloxacin), at three different concentrations in irrigation water (0.5, 5, and 25 μg L -1 ) in relation to three varying volumetric soil moisture depletion levels of 14 % (-4.26 kPa), 10 % (-8.66 kPa), and 7 % (-18.37 kPa) by various vegetable crop species. Experiments were conducted in a split-split block completely randomized design. PPCPs were extracted using a developed method of accelerated solvent extraction and solid phase extraction and analyzed via liquid chromatography mass spectrometry (LCMS). Results indicate that all treated crops were capable of PPCP uptake at nanogram per gram concentrations independent of the applied soil moisture depletion levels and PPCP concentrations. Ofloxacin was the chemical with the highest uptake amounts, followed by atenolol and then diclofenac. Although the results were not statistically significant, higher concentrations of PPCPs were detected in plants maintained under higher soil moisture levels of 14 % (-4.26 kPa).

Comment on "Habitat split and the global decline of amphibians".

PubMed

Cannatella, David C

2008-05-16

Becker et al. (Reports, 14 December 2007, p. 1775) reported that forest amphibians with terrestrial development are less susceptible to the effects of habitat degradation than those with aquatic larvae. However, analysis with more appropriate statistical methods suggests there is no evidence for a difference between aquatic-reproducing and terrestrial-reproducing species.

The Split Virus Influenza Vaccine rapidly activates immune cells through Fcγ receptors.

PubMed

O'Gorman, William E; Huang, Huang; Wei, Yu-Ling; Davis, Kara L; Leipold, Michael D; Bendall, Sean C; Kidd, Brian A; Dekker, Cornelia L; Maecker, Holden T; Chien, Yueh-Hsiu; Davis, Mark M

2014-10-14

Seasonal influenza vaccination is one of the most common medical procedures and yet the extent to which it activates the immune system beyond inducing antibody production is not well understood. In the United States, the most prevalent formulations of the vaccine consist of degraded or "split" viral particles distributed without any adjuvants. Based on previous reports we sought to determine whether the split influenza vaccine activates innate immune receptors-specifically Toll-like receptors. High-dimensional proteomic profiling of human whole-blood using Cytometry by Time-of-Flight (CyTOF) was used to compare signaling pathway activation and cytokine production between the split influenza vaccine and a prototypical TLR response ex vivo. This analysis revealed that the split vaccine rapidly and potently activates multiple immune cell types but yields a proteomic signature quite distinct from TLR activation. Importantly, vaccine induced activity was dependent upon the presence of human sera indicating that a serum factor was necessary for vaccine-dependent immune activation. We found this serum factor to be human antibodies specific for influenza proteins and therefore immediate immune activation by the split vaccine is immune-complex dependent. These studies demonstrate that influenza virus "splitting" inactivates any potential adjuvants endogenous to influenza, such as RNA, but in previously exposed individuals can elicit a potent immune response by facilitating the rapid formation of immune complexes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Spin splitting generated in a Y-shaped semiconductor nanostructure with a quantum point contact

NASA Astrophysics Data System (ADS)

Wójcik, P.; Adamowski, J.; Wołoszyn, M.; Spisak, B. J.

2015-07-01

We have studied the spin splitting of the current in the Y-shaped semiconductor nanostructure with a quantum point contact (QPC) in a perpendicular magnetic field. Our calculations show that the appropriate tuning of the QPC potential and the external magnetic field leads to an almost perfect separation of the spin-polarized currents: electrons with opposite spins flow out through different output branches. The spin splitting results from the joint effect of the QPC, the spin Zeeman splitting, and the electron transport through the edge states formed in the nanowire at the sufficiently high magnetic field. The Y-shaped nanostructure can be used to split the unpolarized current into two spin currents with opposite spins as well as to detect the flow of the spin current. We have found that the separation of the spin currents is only slightly affected by the Rashba spin-orbit coupling. The spin-splitter device is an analogue of the optical device—the birefractive crystal that splits the unpolarized light into two beams with perpendicular polarizations. In the magnetic-field range, in which the current is carried through the edges states, the spin splitting is robust against the spin-independent scattering. This feature opens up a possibility of the application of the Y-shaped nanostructure as a non-ballistic spin-splitter device in spintronics.

Spin splitting generated in a Y-shaped semiconductor nanostructure with a quantum point contact

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

Wójcik, P., E-mail: pawel.wojcik@fis.agh.edu.pl; Adamowski, J., E-mail: janusz.adamowski@fis.agh.edu.pl; Wołoszyn, M.

2015-07-07

We have studied the spin splitting of the current in the Y-shaped semiconductor nanostructure with a quantum point contact (QPC) in a perpendicular magnetic field. Our calculations show that the appropriate tuning of the QPC potential and the external magnetic field leads to an almost perfect separation of the spin-polarized currents: electrons with opposite spins flow out through different output branches. The spin splitting results from the joint effect of the QPC, the spin Zeeman splitting, and the electron transport through the edge states formed in the nanowire at the sufficiently high magnetic field. The Y-shaped nanostructure can be usedmore » to split the unpolarized current into two spin currents with opposite spins as well as to detect the flow of the spin current. We have found that the separation of the spin currents is only slightly affected by the Rashba spin-orbit coupling. The spin-splitter device is an analogue of the optical device—the birefractive crystal that splits the unpolarized light into two beams with perpendicular polarizations. In the magnetic-field range, in which the current is carried through the edges states, the spin splitting is robust against the spin-independent scattering. This feature opens up a possibility of the application of the Y-shaped nanostructure as a non-ballistic spin-splitter device in spintronics.« less

Effect of the use of combination uridine triphosphate, cytidine monophosphate, and hydroxycobalamin on the recovery of neurosensory disturbance after bilateral sagittal split osteotomy: a randomized, double-blind trial.

PubMed

Vieira, C L; Vasconcelos, B C do E; Leão, J C; Laureano Filho, J R

2016-02-01

The change in neurosensory lesions that develop after bilateral sagittal split osteotomy (BSSO) was explored, and the influence of the application of combination uridine triphosphate (UTP), cytidine monophosphate (CMP), and hydroxycobalamin (vitamin B12) on patient outcomes was assessed. This was a randomized, controlled, double-blind trial. The study sample comprised 12 patients, each evaluated on both sides (thus 24 sides). All patients fulfilled defined selection criteria. Changes in the lesions were measured both subjectively and objectively. The sample was divided into two patient groups: an experimental group receiving medication and a control group receiving placebo. The statistical analysis was performed using SPSS software. Lesions in both groups improved and no statistically significant difference between the groups was observed at any time. 'Severe' injuries in the experimental group were more likely to exhibit a significant improvement after 6 months. Based on the results of the present study, it is concluded that the combination UTP, CMP, and hydroxycobalamin did not influence recovery from neurosensory disorders. Copyright © 2015. Published by Elsevier Ltd.

Generalized statistical mechanics of cosmic rays: Application to positron-electron spectral indices.

PubMed

Yalcin, G Cigdem; Beck, Christian

2018-01-29

Cosmic ray energy spectra exhibit power law distributions over many orders of magnitude that are very well described by the predictions of q-generalized statistical mechanics, based on a q-generalized Hagedorn theory for transverse momentum spectra and hard QCD scattering processes. QCD at largest center of mass energies predicts the entropic index to be [Formula: see text]. Here we show that the escort duality of the nonextensive thermodynamic formalism predicts an energy split of effective temperature given by Δ [Formula: see text] MeV, where T H is the Hagedorn temperature. We carefully analyse the measured data of the AMS-02 collaboration and provide evidence that the predicted temperature split is indeed observed, leading to a different energy dependence of the e + and e - spectral indices. We also observe a distinguished energy scale E *  ≈ 50 GeV where the e + and e - spectral indices differ the most. Linear combinations of the escort and non-escort q-generalized canonical distributions yield excellent agreement with the measured AMS-02 data in the entire energy range.

Tablet Splitting of Antiepileptic Drugs in Pediatric Epilepsy: Potential Effect on Plasma Drug Concentrations.

PubMed

Nidanapu, Ravi Prasad; Rajan, Sundaram; Mahadevan, Subramanian; Gitanjali, Batmanabane

2016-12-01

Tablet splitting is the process of dividing a tablet into portions to obtain a prescribed dose of medication. Very few studies have investigated whether split parts of a tablet deliver the expected amount of drug to patients. Our objectives were to evaluate the split parts of adult-dose tablet formulations for percentage of weight deviation, weight uniformity, weight loss, drug content, and the content uniformity of four antiepileptic drugs (AEDs) prescribed to pediatric patients. We also measured AED plasma concentrations in the children. We chose to study first-line AEDs (phenytoin sodium [PHE], sodium valproate [SVA], carbamazepine, and phenobarbitone) as they are routinely prescribed in India. We asked caregivers to perform the same splitting process they follow in their homes on three whole tablets during their routine visit to the outpatient department. After caregivers split the tablets, we studied the weight and content of the split parts. We also used high-performance liquid chromatography to study plasma drug concentrations in children who had received split AEDs for at least 4 months. A total of 168 caregivers participated in the study, and we analyzed 1098 split tablet parts. In total, 539 (49.0 %) split parts were above the specified limit of the 2010 Indian Pharmacopeia (IP) acceptable percentage weight deviation (PHE 169 [48.8 %], SVA 187 [51.9 %], carbamazepine 56 [41.1 %], phenobarbitone 127 [49.6 %]); 456 (41.5 %) split parts were outside the proxy IP specification for drug content (PHE 135 [39.0 %], SVA 140 [38.8 %], carbamazepine 51 [37.5 %], phenobarbitone 130 [50.7 %]), and 253 split parts were outside the acceptable content uniformity range of <85 % and >115 % (PHE 85 [24.5 %], SVA 98 [27.2 %], carbamazepine 14 [10.2 %], phenobarbitone 56 [21.8 %]). In total, 130 (72.2 %) patients had plasma drug concentrations outside the therapeutic range (PHE 36 [72.0 %], SVA 39 [78.0 %], carbamazepine 34 [68.0 %], phenobarbitone 21 [70.0 %]). Splitting adult-dosage formulations of AEDs results in patients not receiving the optimal dose. Plasma drug concentrations are also not optimal. Pediatric dosage formulations should be preferred to splitting adult-dosage formulations in pediatric epilepsy.

Water pair potential of near spectroscopic accuracy. II. Vibration-rotation-tunneling levels of the water dimer

NASA Astrophysics Data System (ADS)

Groenenboom, G. C.; Wormer, P. E. S.; van der Avoird, A.; Mas, E. M.; Bukowski, R.; Szalewicz, K.

2000-10-01

Nearly exact six-dimensional quantum calculations of the vibration-rotation-tunneling (VRT) levels of the water dimer for values of the rotational quantum numbers J and K ⩽2 show that the SAPT-5s water pair potential presented in the preceding paper (paper I) gives a good representation of the experimental high-resolution far-infrared spectrum of the water dimer. After analyzing the sensitivity of the transition frequencies with respect to the linear parameters in the potential we could further improve this potential by using only one of the experimentally determined tunneling splittings of the ground state in (H2O)2. The accuracy of the resulting water pair potential, SAPT-5st, is established by comparison with the spectroscopic data of both (H2O)2 and (D2O)2: ground and excited state tunneling splittings and rotational constants, as well as the frequencies of the intermolecular vibrations.

Quadratic String Method for Locating Instantons in Tunneling Splitting Calculations.

PubMed

Cvitaš, Marko T

2018-03-13

The ring-polymer instanton (RPI) method is an efficient technique for calculating approximate tunneling splittings in high-dimensional molecular systems. In the RPI method, tunneling splitting is evaluated from the properties of the minimum action path (MAP) connecting the symmetric wells, whereby the extensive sampling of the full potential energy surface of the exact quantum-dynamics methods is avoided. Nevertheless, the search for the MAP is usually the most time-consuming step in the standard numerical procedures. Recently, nudged elastic band (NEB) and string methods, originaly developed for locating minimum energy paths (MEPs), were adapted for the purpose of MAP finding with great efficiency gains [ J. Chem. Theory Comput. 2016 , 12 , 787 ]. In this work, we develop a new quadratic string method for locating instantons. The Euclidean action is minimized by propagating the initial guess (a path connecting two wells) over the quadratic potential energy surface approximated by means of updated Hessians. This allows the algorithm to take many minimization steps between the potential/gradient calls with further reductions in the computational effort, exploiting the smoothness of potential energy surface. The approach is general, as it uses Cartesian coordinates, and widely applicable, with computational effort of finding the instanton usually lower than that of determining the MEP. It can be combined with expensive potential energy surfaces or on-the-fly electronic-structure methods to explore a wide variety of molecular systems.

Potential-sensing electrochemical atomic force microscopy for in operando analysis of water-splitting catalysts and interfaces

NASA Astrophysics Data System (ADS)

Nellist, Michael R.; Laskowski, Forrest A. L.; Qiu, Jingjing; Hajibabaei, Hamed; Sivula, Kevin; Hamann, Thomas W.; Boettcher, Shannon W.

2018-01-01

Heterogeneous electrochemical phenomena, such as (photo)electrochemical water splitting to generate hydrogen using semiconductors and/or electrocatalysts, are driven by the accumulated charge carriers and thus the interfacial electrochemical potential gradients that promote charge transfer. However, measurements of the "surface" electrochemical potential during operation are not generally possible using conventional electrochemical techniques, which measure/control the potential of a conducting electrode substrate. Here we show that the nanoscale conducting tip of an atomic force microscope cantilever can sense the surface electrochemical potential of electrocatalysts in operando. To demonstrate utility, we measure the potential-dependent and thickness-dependent electronic properties of cobalt (oxy)hydroxide phosphate (CoPi). We then show that CoPi, when deposited on illuminated haematite (α-Fe2O3) photoelectrodes, acts as both a hole collector and an oxygen evolution catalyst. We demonstrate the versatility of the technique by comparing surface potentials of CoPi-decorated planar and mesoporous haematite and discuss viability for broader application in the study of electrochemical phenomena.

Quantum impurity models for magnetic adsorbates on superconductor surfaces

NASA Astrophysics Data System (ADS)

Žitko, Rok

2018-05-01

Magnetic atoms adsorbed on surfaces have a quenched orbital moment while their ground-state spin multiplet is partially split as a consequence of the spin-orbit coupling which, even if intrinsically weak, has a large effect due to the abrupt change of the potential at the surface. Such metal adsorbates should be modelled using quantum impurity models that include the relevant internal degrees of freedom and the interaction terms, in particular the magnetic anisotropy and the Kondo exchange coupling. When adsorbed on superconducting surfaces, these impurities have complex spectra of sub-gap excitations due to magnetic anisotropy splitting and Kondo screening. Both anisotropy splitting and Zeeman splitting due to the external magnetic field are significantly renormalized by the coupling to the substrate electrons. In this work I discuss the quantum-to-classical crossover and the applicability of classical static-local-spin picture for discussing magnetic nanostructures on superconductors.

Theoretical analysis of polarization-coupled mode splitting in a single microfiber knot-ring resonator

NASA Astrophysics Data System (ADS)

Qiu, Weiqia; Zhou, Junjie; Yu, Jianhui; Xiao, Yi; Lu, Huihui; Guan, Heyuan; Zhong, Yongchun; Zhang, Jun; Chen, Zhe

2016-06-01

We established a theoretical model for a single knot-ring resonator and investigated the transmission spectrum by Jones matrix. The numerical results show that two orthogonal polarization modes of knot-ring, which are originally resonated at the same wavelength, will split into two resonant modes with different wavelengths. The mode splitting is due to the coupling between the two orthogonal polarization modes in the knot-ring when the twisted angle of the twist coupler is not exactly equal to 2mπ (m is an integer). It is also found that the separation of the mode splitting is linearly proportional to the deviation angle δθ with a high correlation coefficient of 99.6% and a slope of 3.17 nm/rad. Furthermore, a transparency phenomenon analogous to coupled-resonator-induced transparency was also predicted by the model. These findings may have potential applications in lasers and sensors.

Automatic detection of cone photoreceptors in split detector adaptive optics scanning light ophthalmoscope images.

PubMed

Cunefare, David; Cooper, Robert F; Higgins, Brian; Katz, David F; Dubra, Alfredo; Carroll, Joseph; Farsiu, Sina

2016-05-01

Quantitative analysis of the cone photoreceptor mosaic in the living retina is potentially useful for early diagnosis and prognosis of many ocular diseases. Non-confocal split detector based adaptive optics scanning light ophthalmoscope (AOSLO) imaging reveals the cone photoreceptor inner segment mosaics often not visualized on confocal AOSLO imaging. Despite recent advances in automated cone segmentation algorithms for confocal AOSLO imagery, quantitative analysis of split detector AOSLO images is currently a time-consuming manual process. In this paper, we present the fully automatic adaptive filtering and local detection (AFLD) method for detecting cones in split detector AOSLO images. We validated our algorithm on 80 images from 10 subjects, showing an overall mean Dice's coefficient of 0.95 (standard deviation 0.03), when comparing our AFLD algorithm to an expert grader. This is comparable to the inter-observer Dice's coefficient of 0.94 (standard deviation 0.04). To the best of our knowledge, this is the first validated, fully-automated segmentation method which has been applied to split detector AOSLO images.

Neutron-proton effective mass splitting in terms of symmetry energy and its density slope

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

Chakraborty, S.; Sahoo, B.; Sahoo, S., E-mail: sukadevsahoo@yahoo.com

2015-01-15

Using a simple density-dependent finite-range effective interaction having Yukawa form, the density dependence of isoscalar and isovector effective masses is studied. The isovector effective mass is found to be different for different pairs of like and unlike nucleons. Using HVH theorem, the neutron-proton effective mass splitting is represented in terms of symmetry energy and its density slope. It is again observed that the neutron-proton effective mass splitting has got a positive value when isoscalar effective mass is greater than the isovector effective mass and has a negative value for the opposite case. Furthermore, the neutron-proton effective mass splitting is foundmore » to have a linear dependence on asymmetry β. The second-order symmetry potential has a vital role in the determination of density slope of symmetry energy but it does not have any contribution on neutron-proton effective mass splitting. The finite-range effective interaction is compared with the SLy2, SKM, f{sub −}, f{sub 0}, and f{sub +} forms of interactions.« less

Conceptual Design and Optimal Power Control Strategy for AN Eco-Friendly Hybrid Vehicle

NASA Astrophysics Data System (ADS)

Nasiri, N. Mir; Chieng, Frederick T. A.

2011-06-01

This paper presents a new concept for a hybrid vehicle using a torque and speed splitting technique. It is implemented by the newly developed controller in combination with a two degree of freedom epicyclic gear transmission. This approach enables optimization of the power split between the less powerful electrical motor and more powerful engine while driving a car load. The power split is fundamentally a dual-energy integration mechanism as it is implemented by using the epicyclic gear transmission that has two inputs and one output for a proper power distribution. The developed power split control system manages the operation of both the inputs to have a known output with the condition of maintaining optimum operating efficiency of the internal combustion engine and electrical motor. This system has a huge potential as it is possible to integrate all the features of hybrid vehicle known to-date such as the regenerative braking system, series hybrid, parallel hybrid, series/parallel hybrid, and even complex hybrid (bidirectional). By using the new power split system it is possible to further reduce fuel consumption and increase overall efficiency.

Model validations for low-global warming potential refrigerants in mini-split air-conditioning units

DOE PAGES

Shen, Bo; Shrestha, Som; Abdelaziz, Omar

2016-09-02

To identify low GWP (global warming potential) refrigerants to replace R-22 and R-410A, extensive experimental evaluations were conducted for multiple candidates of refrigerant at the standard test conditions and at high-ambient conditions with outdoor temperature varying from 27.8 C to 55.0 C.. In the study, R-22 was compared to propane (R-290), DR-3, ARM-20B, N-20B and R-444B in a mini-split air conditioning unit originally designed for R-22; R-410A was compared to R-32, DR-55, ARM-71A, L41-2 (R-447A) in a mini-split unit designed for R-410A. To reveal physics behind the measured performance results, thermodynamic properties of the alternative refrigerants were analysed. In addition,more » the experimental data was used to calibrate a physics-based equipment model, i.e. ORNL Heat Pump Design Model (HPDM). The calibrated model translated the experimental results to key calculated parameters, i.e. compressor efficiencies, refrigerant side two-phase heat transfer coefficients, corresponding to each refrigerant. As a result, these calculated values provide scientific insights on the performance of the alternative refrigerants and are useful for other applications beyond mini-split air conditioning units.« less

Spin-orbit coupling calculations with the two-component normalized elimination of the small component method

NASA Astrophysics Data System (ADS)

Filatov, Michael; Zou, Wenli; Cremer, Dieter

2013-07-01

A new algorithm for the two-component Normalized Elimination of the Small Component (2cNESC) method is presented and tested in the calculation of spin-orbit (SO) splittings for a series of heavy atoms and their molecules. The 2cNESC is a Dirac-exact method that employs the exact two-component one-electron Hamiltonian and thus leads to exact Dirac SO splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000), 10.1103/PhysRevB.62.7809]. The use of the screened nucleus potential for the two-electron SO interaction leads to accurate spinor energy splittings, for which the deviations from the accurate Dirac Fock-Coulomb values are on the average far below the deviations observed for other effective one-electron SO operators. For hydrogen halides HX (X = F, Cl, Br, I, At, and Uus) and mercury dihalides HgX2 (X = F, Cl, Br, I) trends in spinor energies and SO splittings as obtained with the 2cNESC method are analyzed and discussed on the basis of coupling schemes and the electronegativity of X.

Model validations for low-global warming potential refrigerants in mini-split air-conditioning units

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

Shen, Bo; Shrestha, Som; Abdelaziz, Omar

To identify low GWP (global warming potential) refrigerants to replace R-22 and R-410A, extensive experimental evaluations were conducted for multiple candidates of refrigerant at the standard test conditions and at high-ambient conditions with outdoor temperature varying from 27.8 C to 55.0 C.. In the study, R-22 was compared to propane (R-290), DR-3, ARM-20B, N-20B and R-444B in a mini-split air conditioning unit originally designed for R-22; R-410A was compared to R-32, DR-55, ARM-71A, L41-2 (R-447A) in a mini-split unit designed for R-410A. To reveal physics behind the measured performance results, thermodynamic properties of the alternative refrigerants were analysed. In addition,more » the experimental data was used to calibrate a physics-based equipment model, i.e. ORNL Heat Pump Design Model (HPDM). The calibrated model translated the experimental results to key calculated parameters, i.e. compressor efficiencies, refrigerant side two-phase heat transfer coefficients, corresponding to each refrigerant. As a result, these calculated values provide scientific insights on the performance of the alternative refrigerants and are useful for other applications beyond mini-split air conditioning units.« less

Surface properties of lead-free halide double perovskites: Possible visible-light photo-catalysts for water splitting

NASA Astrophysics Data System (ADS)

Volonakis, George; Giustino, Feliciano

2018-06-01

Halide double perovskites based on combinations of monovalent and trivalent cations have been proposed as promising lead-free alternatives to lead halide perovskites. Among the newly synthesized compounds Cs2BiAgCl6, Cs2BiAgBr6, Cs2SbAgCl6, and Cs2InAgCl6, some exhibit bandgaps in the visible range and all have low carrier effective masses; therefore, these materials constitute potential candidates for various opto-electronic applications. Here, we use first-principles calculations to investigate the electronic properties of the surfaces of these four compounds and determine, for the first time, their ionization potential and electron affinity. We find that the double perovskites Cs2BiAgCl6 and Cs2BiAgBr6 are potentially promising materials for photo-catalytic water splitting, while Cs2InAgCl6 and Cs2SbAgCl6 would require controlling their surface termination to obtain energy levels appropriate for water splitting. The energy of the halogen p orbitals is found to control the conduction band level; therefore, we propose that mixed halides could be used to fine-tune the electronic affinity.

Monte Carlo based modelling approach for designing and predicting cytotoxicity of 2-phenylindole derivatives against breast cancer cell line MCF7.

PubMed

Gaikwad, Ruchi; Ghorai, Soumajit; Amin, Sk Abdul; Adhikari, Nilanjan; Patel, Tarun; Das, Kalpataru; Jha, Tarun; Gayen, Shovanlal

2018-06-01

Breast cancer is one of the leading causes of cancers among the variety of cancers in woman all over the world. Compounds with phenylindole scaffold were found to execute promising cytotoxicity against breast cancer cell line MCF7. In the present study, a Monte Carlo based QSAR analysis was performed on a dataset containing 102 phenylindoles in order to accelerate the efforts to find out better cytotoxic phenylindoles against MCF7 cell line. The statistical qualities of the generated models were found to be quite good as far as the internal and external validation were concerned. The best models from each split (Split 1: R 2  = 0.6944, Q 2  = 0.6495; Split 2: R 2  = 0.8202, Q 2  = 0.7998; Split 3: R 2  = 0.8603, Q 2  = 0.8357) for the test set were selected and Y-scrambling test and applicability domain analysis were also performed to ensure the robustness of these models. Among these models, model from split 3 obtained by using hybrid descriptors (combination of SMILES and HSG with 0 ECk connectivity) was used to identify and classify the structural attributes as promoters as well as hinderers of cytotoxicity for these 2-phenylindole derivatives. Results from the analysis were further used to design and predict some probable new 2-phenylindole derivatives having promising cytotoxicity (IC 50  < 55 nM) against MCF7. Copyright © 2018 Elsevier Ltd. All rights reserved.

Metal-dielectric composites for beam splitting and far-field deep sub-wavelength resolution for visible wavelengths.

PubMed

Yan, Changchun; Zhang, Dao Hua; Zhang, Yuan; Li, Dongdong; Fiddy, M A

2010-07-05

We report beam splitting in a metamaterial composed of a silver-alumina composite covered by a layer of chromium containing one slit. By simulating distributions of energy flow in the metamaterial for H-polarized waves, we find that the beam splitting occurs when the width of the slit is shorter than the wavelength, which is conducive to making a beam splitter in sub-wavelength photonic devices. We also find that the metamaterial possesses deep sub-wavelength resolution capabilities in the far field when there are two slits and the central silver layer is at least 36 nm in thickness, which has potential applications in superresolution imaging.

Paired split-plot designs of multireader multicase studies.

PubMed

Chen, Weijie; Gong, Qi; Gallas, Brandon D

2018-07-01

The widely used multireader multicase ROC study design for comparing imaging modalities is the fully crossed (FC) design: every reader reads every case of both modalities. We investigate paired split-plot (PSP) designs that may allow for reduced cost and increased flexibility compared with the FC design. In the PSP design, case images from two modalities are read by the same readers, thereby the readings are paired across modalities. However, within each modality, not every reader reads every case. Instead, both the readers and the cases are partitioned into a fixed number of groups and each group of readers reads its own group of cases-a split-plot design. Using a [Formula: see text]-statistic based variance analysis for AUC (i.e., area under the ROC curve), we show analytically that precision can be gained by the PSP design as compared with the FC design with the same number of readers and readings. Equivalently, we show that the PSP design can achieve the same statistical power as the FC design with a reduced number of readings. The trade-off for the increased precision in the PSP design is the cost of collecting a larger number of truth-verified patient cases than the FC design. This means that one can trade-off between different sources of cost and choose a least burdensome design. We provide a validation study to show the iMRMC software can be reliably used for analyzing data from both FC and PSP designs. Finally, we demonstrate the advantages of the PSP design with a reader study comparing full-field digital mammography with screen-film mammography.

Use of the Monte Carlo Method for OECD Principles-Guided QSAR Modeling of SIRT1 Inhibitors.

PubMed

Kumar, Ashwani; Chauhan, Shilpi

2017-01-01

SIRT1 inhibitors offer therapeutic potential for the treatment of a number of diseases including cancer and human immunodeficiency virus infection. A diverse series of 45 compounds with reported SIRT1 inhibitory activity has been employed for the development of quantitative structure-activity relationship (QSAR) models using the Monte Carlo optimization method. This method makes use of simplified molecular input line entry system notation of the molecular structure. The QSAR models were built up according to OECD principles. Three subsets of three splits were examined and validated by respective external sets. All the three described models have good statistical quality. The best model has the following statistical characteristics: R 2  = 0.8350, Q 2 test  = 0.7491 for the test set and R 2  = 0.9655, Q 2 ext  = 0.9261 for the validation set. In the mechanistic interpretation, structural attributes responsible for the endpoint increase and decrease are defined. Further, the design of some prospective SIRT1 inhibitors is also presented on the basis of these structural attributes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of Group Sandtray Therapy on the Self-Esteem of Young Adolescent Girls

ERIC Educational Resources Information Center

Shen, Yu-Pei; Armstrong, Stephen A.

2008-01-01

The effectiveness of group sandtray therapy was examined using a pretest-posttest control group design with young adolescent girls (n = 37) identified as having low self-esteem. A split-plot analysis of variance (SPANOVA) revealed statistically significant differences between participants in the treatment and control groups in self-esteem on five…

NHEXAS PHASE I MARYLAND STUDY--STANDARD OPERATING PROCEDURE FOR EXPLORATORY DATA ANALYSIS AND SUMMARY STATISTICS (D05)

EPA Science Inventory

This SOP describes the methods and procedures for two types of QA procedures: spot checks of hand entered data, and QA procedures for co-located and split samples. The spot checks were used to determine whether the error rate goal for the input of hand entered data was being att...

Resolving microstructures in Z pinches with intensity interferometry

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

Apruzese, J. P.; Kroupp, E.; Maron, Y.

2014-03-15

Nearly 60 years ago, Hanbury Brown and Twiss [R. Hanbury Brown and R. Q. Twiss, Nature 178, 1046 (1956)] succeeded in measuring the 30 nrad angular diameter of Sirius using a new type of interferometry that exploited the interference of photons independently emitted from different regions of the stellar disk. Its basis was the measurement of intensity correlations as a function of detector spacing, with no beam splitting or preservation of phase information needed. Applied to Z pinches, X pinches, or laser-produced plasmas, this method could potentially provide spatial resolution under one micron. A quantitative analysis based on the workmore » of Purcell [E. M. Purcell, Nature 178, 1449 (1956)] reveals that obtaining adequate statistics from x-ray interferometry of a Z-pinch microstructure would require using the highest-current generators available. However, using visible light interferometry would reduce the needed photon count and could enable its use on sub-MA machines.« less

Metric Learning to Enhance Hyperspectral Image Segmentation

NASA Technical Reports Server (NTRS)

Thompson, David R.; Castano, Rebecca; Bue, Brian; Gilmore, Martha S.

2013-01-01

Unsupervised hyperspectral image segmentation can reveal spatial trends that show the physical structure of the scene to an analyst. They highlight borders and reveal areas of homogeneity and change. Segmentations are independently helpful for object recognition, and assist with automated production of symbolic maps. Additionally, a good segmentation can dramatically reduce the number of effective spectra in an image, enabling analyses that would otherwise be computationally prohibitive. Specifically, using an over-segmentation of the image instead of individual pixels can reduce noise and potentially improve the results of statistical post-analysis. In this innovation, a metric learning approach is presented to improve the performance of unsupervised hyperspectral image segmentation. The prototype demonstrations attempt a superpixel segmentation in which the image is conservatively over-segmented; that is, the single surface features may be split into multiple segments, but each individual segment, or superpixel, is ensured to have homogenous mineralogy.

Efficacy of autologous platelet-rich plasma combined with fractional ablative carbon dioxide resurfacing laser in treatment of facial atrophic acne scars: A split-face randomized clinical trial.

PubMed

Faghihi, Gita; Keyvan, Shima; Asilian, Ali; Nouraei, Saeid; Behfar, Shadi; Nilforoushzadeh, Mohamad Ali

2016-01-01

Autologous platelet-rich plasma has recently attracted significant attention throughout the medical field for its wound-healing ability. This study was conducted to investigate the potential of platelet-rich plasma combined with fractional laser therapy in the treatment of acne scarring. Sixteen patients (12 women and 4 men) who underwent split-face therapy were analyzed in this study. They received ablative fractional carbon dioxide laser combined with intradermal platelet-rich plasma treatment on one half of their face and ablative fractional carbon dioxide laser with intradermal normal saline on the other half. The injections were administered immediately after laser therapy. The treatment sessions were repeated after an interval of one month. The clinical response was assessed based on patient satisfaction and the objective evaluation of serial photographs by two blinded dermatologists at baseline, 1 month after the first treatment session and 4 months after the second. The adverse effects including erythema and edema were scored by participants on days 0, 2, 4, 6, 8, 15 and 30 after each session. Overall clinical improvement of acne scars was higher on the platelet-rich plasma-fractional carbon dioxide laser treated side but the difference was not statistically significant either 1 month after the first treatment session (P = 0.15) or 4 months after the second (P = 0.23). In addition, adverse effects (erythema and edema) on the platelet-rich plasma-fractional carbon dioxide laser-treated side were more severe and of longer duration. Small sample size, absence of all skin phototypes within the study group and lack of objective methods for the evaluation of response to treatment and adverse effects were the limitations. This study demonstrated that adding platelet-rich plasma to fractional carbon dioxide laser treatment did not produce any statistically significant synergistic effects and also resulted in more severe side effects and longer downtime.

Resonance hybridization and near field properties of strongly coupled plasmonic ring dimer-rod nanosystem

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

Koya, Alemayehu Nana; Ji, Boyu; Hao, Zuoqiang

2015-09-21

Combined effects of polarization, split gap, and rod width on the resonance hybridization and near field properties of strongly coupled gold dimer-rod nanosystem are comparatively investigated in the light of the constituent nanostructures. By aligning polarization of the incident light parallel to the long axis of the nanorod, introducing small split gaps to the dimer walls, and varying width of the nanorod, we have simultaneously achieved resonance mode coupling, huge near field enhancement, and prolonged plasmon lifetime. As a result of strong coupling between the nanostructures and due to an intense confinement of near fields at the split and dimer-rodmore » gaps, the extinction spectrum of the coupled nanosystem shows an increase in intensity and blueshift in wavelength. Consequently, the near field lifespan of the split-nanosystem is prolonged in contrast to the constituent nanostructures and unsplit-nanosystem. On the other hand, for polarization of the light perpendicular to the long axis of the nanorod, the effect of split gap on the optical responses of the coupled nanosystem is found to be insignificant compared to the parallel polarization. These findings and such geometries suggest that coupling an array of metallic split-ring dimer with long nanorod can resolve the huge radiative loss problem of plasmonic waveguide. In addition, the Fano-like resonances and immense near field enhancements at the split and dimer-rod gaps imply the potentials of the nanosystem for practical applications in localized surface plasmon resonance spectroscopy and sensing.« less

Toward a General Approach for RNA-Templated Hierarchical Assembly of Split-Proteins

PubMed Central

Furman, Jennifer L.; Badran, Ahmed H.; Ajulo, Oluyomi; Porter, Jason R.; Stains, Cliff I.; Segal, David J.; Ghosh, Indraneel

2010-01-01

The ability to conditionally turn on a signal or induce a function in the presence of a user-defined RNA target has potential applications in medicine and synthetic biology. Although sequence-specific pumilio repeat proteins can target a limited set of ssRNA sequences, there are no general methods for targeting ssRNA with designed proteins. As a first step toward RNA recognition, we utilized the RNA binding domain of argonaute, implicated in RNA interference, for specifically targeting generic 2-nucleotide, 3' overhangs of any dsRNA. We tested the reassembly of a split-luciferase enzyme guided by argonaute-mediated recognition of newly generated nucleotide overhangs when ssRNA is targeted by a designed complementary guide sequence. This approach was successful when argonaute was utilized in conjunction with a pumilio repeat and expanded the scope of potential ssRNA targets. However, targeting any desired ssRNA remained elusive as two argonaute domains provided minimal reassembled split-luciferase. We next designed and tested a second hierarchical assembly, wherein ssDNA guides are appended to DNA hairpins that serve as a scaffold for high affinity zinc fingers attached to split-luciferase. In the presence of a ssRNA target containing adjacent sequences complementary to the guides, the hairpins are brought into proximity, allowing for zinc finger binding and concomitant reassembly of the fragmented luciferase. The scope of this new approach was validated by specifically targeting RNA encoding VEGF, hDM2, and HER2. These approaches provide potentially general design paradigms for the conditional reassembly of fragmented proteins in the presence of any desired ssRNA target. PMID:20681585

Entropy Splitting and Numerical Dissipation

NASA Technical Reports Server (NTRS)

Yee, H. C.; Vinokur, M.; Djomehri, M. J.

1999-01-01

A rigorous stability estimate for arbitrary order of accuracy of spatial central difference schemes for initial-boundary value problems of nonlinear symmetrizable systems of hyperbolic conservation laws was established recently by Olsson and Oliger (1994) and Olsson (1995) and was applied to the two-dimensional compressible Euler equations for a perfect gas by Gerritsen and Olsson (1996) and Gerritsen (1996). The basic building block in developing the stability estimate is a generalized energy approach based on a special splitting of the flux derivative via a convex entropy function and certain homogeneous properties. Due to some of the unique properties of the compressible Euler equations for a perfect gas, the splitting resulted in the sum of a conservative portion and a non-conservative portion of the flux derivative. hereafter referred to as the "Entropy Splitting." There are several potential desirable attributes and side benefits of the entropy splitting for the compressible Euler equations that were not fully explored in Gerritsen and Olsson. The paper has several objectives. The first is to investigate the choice of the arbitrary parameter that determines the amount of splitting and its dependence on the type of physics of current interest to computational fluid dynamics. The second is to investigate in what manner the splitting affects the nonlinear stability of the central schemes for long time integrations of unsteady flows such as in nonlinear aeroacoustics and turbulence dynamics. If numerical dissipation indeed is needed to stabilize the central scheme, can the splitting help minimize the numerical dissipation compared to its un-split cousin? Extensive numerical study on the vortex preservation capability of the splitting in conjunction with central schemes for long time integrations will be presented. The third is to study the effect of the non-conservative proportion of splitting in obtaining the correct shock location for high speed complex shock-turbulence interactions. The fourth is to determine if this method can be extended to other physical equations of state and other evolutionary equation sets. If numerical dissipation is needed, the Yee, Sandham, and Djomehri (1999) numerical dissipation is employed. The Yee et al. schemes fit in the Olsson and Oliger framework.

Toward a High-Efficient Utilization of Solar Radiation by Quad-Band Solar Spectral Splitting.

PubMed

Cao, Feng; Huang, Yi; Tang, Lu; Sun, Tianyi; Boriskina, Svetlana V; Chen, Gang; Ren, Zhifeng

2016-12-01

The promising quad-band solar spectral splitter incorporates the properties of the optical filter and the spectrally selective solar thermal absorber can direct PV band to PV modules and absorb thermal band energy for thermal process with low thermal losses. It provides a new strategy for spectral splitting and offers potential ways for hybrid PVT system design. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Split Forcing Technique to Reduce Log-layer Mismatch in Wall-modeled Turbulent Channel Flows

NASA Astrophysics Data System (ADS)

Deleon, Rey; Senocak, Inanc

2016-11-01

The conventional approach to sustain a flow field in a periodic channel flow seems to be the culprit behind the log-law mismatch problem that has been reported in many studies hybridizing Reynolds-averaged Navier-Stokes (RANS) and large-eddy simulation (LES) techniques, commonly referred to as hybrid RANS-LES. To address this issue, we propose a split-forcing approach that relies only on the conservation of mass principle. We adopt a basic hybrid RANS-LES technique on a coarse mesh with wall-stress boundary conditions to simulate turbulent channel flows at friction Reynolds numbers of 2000 and 5200 and demonstrate good agreement with benchmark data. We also report a duality in velocity scale that is a specific consequence of the split forcing framework applied to hybrid RANS-LES. The first scale is the friction velocity derived from the wall shear stress. The second scale arises in the core LES region, a value different than at the wall. Second-order turbulence statistics agree well with the benchmark data when normalized by the core friction velocity, whereas the friction velocity at the wall remains the appropriate scale for the mean velocity profile. Based on our findings, we suggest reevaluating more sophisticated hybrid RANS-LES approaches within the split-forcing framework. Work funded by National Science Foundation under Grant No. 1056110 and 1229709. First author acknowledges the University of Idaho President's Doctoral Scholars Award.

A STRICTLY CONTRACTIVE PEACEMAN-RACHFORD SPLITTING METHOD FOR CONVEX PROGRAMMING.

PubMed

Bingsheng, He; Liu, Han; Wang, Zhaoran; Yuan, Xiaoming

2014-07-01

In this paper, we focus on the application of the Peaceman-Rachford splitting method (PRSM) to a convex minimization model with linear constraints and a separable objective function. Compared to the Douglas-Rachford splitting method (DRSM), another splitting method from which the alternating direction method of multipliers originates, PRSM requires more restrictive assumptions to ensure its convergence, while it is always faster whenever it is convergent. We first illustrate that the reason for this difference is that the iterative sequence generated by DRSM is strictly contractive, while that generated by PRSM is only contractive with respect to the solution set of the model. With only the convexity assumption on the objective function of the model under consideration, the convergence of PRSM is not guaranteed. But for this case, we show that the first t iterations of PRSM still enable us to find an approximate solution with an accuracy of O (1/ t ). A worst-case O (1/ t ) convergence rate of PRSM in the ergodic sense is thus established under mild assumptions. After that, we suggest attaching an underdetermined relaxation factor with PRSM to guarantee the strict contraction of its iterative sequence and thus propose a strictly contractive PRSM. A worst-case O (1/ t ) convergence rate of this strictly contractive PRSM in a nonergodic sense is established. We show the numerical efficiency of the strictly contractive PRSM by some applications in statistical learning and image processing.

Population splitting of rodlike swimmers in Couette flow.

PubMed

Nili, Hossein; Kheyri, Masoud; Abazari, Javad; Fahimniya, Ali; Naji, Ali

2017-06-28

We present a quantitative analysis on the response of a dilute active suspension of self-propelled rods (swimmers) in a planar channel subjected to an imposed shear flow. To best capture the salient features of the shear-induced effects, we consider the case of an imposed Couette flow, providing a constant shear rate across the channel. We argue that the steady-state behavior of swimmers can be understood in the light of a population splitting phenomenon, occurring as the shear rate exceeds a certain threshold, initiating the reversal of the swimming direction for a finite fraction of swimmers from down- to upstream or vice versa, depending on the swimmer position within the channel. Swimmers thus split into two distinct, statistically significant and oppositely swimming majority and minority populations. The onset of population splitting translates into a transition from a self-propulsion-dominated regime to a shear-dominated regime, corresponding to a unimodal-to-bimodal change in the probability distribution function of the swimmer orientation. We present a phase diagram in terms of the swim and flow Péclet numbers showing the separation of these two regimes by a discontinuous transition line. Our results shed further light on the behavior of swimmers in a shear flow and provide an explanation for the previously reported non-monotonic behavior of the mean, near-wall, parallel-to-flow orientation of swimmers with increasing shear strength.

Torque Splitting by a Concentric Face Gear Transmission

NASA Technical Reports Server (NTRS)

Filler, Robert R.; Heath, Gregory F.; Slaughter, Stephen C.; Lewicki, David G.

2002-01-01

Tests of a 167 Kilowatt (224 Horsepower) split torque face gearbox were performed by the Boeing Company in Mesa, Arizona, while working under a Defense Advanced Research Projects Agency (DARPA) Technology Reinvestment Program (TRP). This paper provides a summary of these cooperative tests, which were jointly funded by Boeing and DARPA. Design, manufacture and testing of the scaled-power TRP proof-of-concept (POC) split torque gearbox followed preliminary evaluations of the concept performed early in the program. The split torque tests were run using 200 N-m (1767 in-lbs) torque input to each side of the transmission. During tests, two input pinions were slow rolled while in mesh with the two face gears. Two idler gears were also used in the configuration to recombine torque near the output. Resistance was applied at the output face gear to create the required loading conditions in the gear teeth. A system of weights, pulleys and cables were used in the test rig to provide both the input and output loading. Strain gages applied in the tooth root fillets provided strain indication used to determine torque splitting conditions at the input pinions. The final two pinion-two idler tests indicated 52% to 48% average torque split capabilities for the two pinions. During the same tests, a 57% to 43% average distribution of the torque being recombined to the upper face gear from the lower face gear was measured between the two idlers. The POC split torque tests demonstrated that face gears can be applied effectively in split torque rotorcraft transmissions, yielding good potential for significant weight, cost and reliability improvements over existing equipment using spiral bevel gearing.

Telecom wavelength single quantum dots with very small excitonic fine-structure splitting

NASA Astrophysics Data System (ADS)

Kors, Andrei; Reithmaier, Johann Peter; Benyoucef, Mohamed

2018-04-01

We report on molecular beam epitaxy growth of symmetric InAs/InP quantum dots (QDs) emitting at a telecom C-band (1.55 μm) with an ultra-small excitonic fine-structure splitting of ˜2 μeV. The QDs are grown on a distributed Bragg reflector (DBR) and systematically characterized by micro-photoluminescence (μ-PL) measurements. One order of magnitude of QD PL intensity enhancement is observed in comparison to the samples without DBR. A combination of power-dependent and polarization-resolved measurements reveals background-free exciton, biexciton, and dark exciton emission with a resolution-limited linewidth below 35 μeV and a biexciton binding energy of ˜1 meV. The results are confirmed by statistical measurements of about 20 QDs.

Imaging nanobubble nucleation and hydrogen spillover during electrocatalytic water splitting.

PubMed

Hao, Rui; Fan, Yunshan; Howard, Marco D; Vaughan, Joshua C; Zhang, Bo

2018-06-05

Nucleation and growth of hydrogen nanobubbles are key initial steps in electrochemical water splitting. These processes remain largely unexplored due to a lack of proper tools to probe the nanobubble's interfacial structure with sufficient spatial and temporal resolution. We report the use of superresolution microscopy to image transient formation and growth of single hydrogen nanobubbles at the electrode/solution interface during electrocatalytic water splitting. We found hydrogen nanobubbles can be generated even at very early stages in water electrolysis, i.e., ∼500 mV before reaching its thermodynamic reduction potential. The ability to image single nanobubbles on an electrode enabled us to observe in real time the process of hydrogen spillover from ultrathin gold nanocatalysts supported on indium-tin oxide.

Brillouin lasing in coupled silica toroid microcavities

NASA Astrophysics Data System (ADS)

Honda, Yoshihiro; Yoshiki, Wataru; Tetsumoto, Tomohiro; Fujii, Shun; Furusawa, Kentaro; Sekine, Norihiko; Tanabe, Takasumi

2018-05-01

We demonstrate stimulated Brillouin scattering lasing in a strongly coupled microcavity system. By coupling two silica toroid microcavities, we achieve large mode splitting of 11 GHz, whose frequency separation matches the Brillouin frequency shift of silica. The stimulated Brillouin scattering light is resonantly amplified by pumping at the higher frequency side of the supermode splitting resonance. Since the mode splitting is adjusted by changing the gap distance between the two cavities, our system does not require precise control of a mm-sized cavity diameter to match the free-spectral spacing with the Brillouin frequency shift. It also allows us to use a small cavity, and hence, our system has the potential to achieve the lasing threshold at a very low power.

The Use of Split-Thickness Skin Grafts on Diabetic Foot Ulcerations: A Literature Review

PubMed Central

McCartan, Brant; Dinh, Thanh

2012-01-01

Diabetic foot ulcerations are historically difficult to treat despite advanced therapeutic modalities. There are numerous modalities described in the literature ranging from noninvasive topical wound care to more invasive surgical procedures such as primary closure, skin flaps, and skin grafting. While skin grafting provides faster time to closure with a single treatment compared to traditional topical wound treatments, the potential risks of donor site morbidity and poor wound healing unique to the diabetic state have been cited as a contraindication to its widespread use. In order to garner clarity on this issue, a literature review was undertaken on the use of split-thickness skin grafts on diabetic foot ulcers. Search of electronic databases yielded four studies that reported split-thickness skin grafts as definitive means of closure. In addition, several other studies employed split-thickness skin grafts as an adjunct to a treatment that was only partially successful or used to fill in the donor site of another plastic surgery technique. When used as the primary closure on optimized diabetic foot ulcerations, split-thickness skin grafts are 78% successful at closing 90% of the wound by eight weeks. PMID:22666573

Splitting of the zero-energy Landau level and universal dissipative conductivity at critical points in disordered graphene.

PubMed

Ortmann, Frank; Roche, Stephan

2013-02-22

We report on robust features of the longitudinal conductivity (σ(xx)) of the graphene zero-energy Landau level in the presence of disorder and varying magnetic fields. By mixing an Anderson disorder potential with a low density of sublattice impurities, the transition from metallic to insulating states is theoretically explored as a function of Landau-level splitting, using highly efficient real-space methods to compute the Kubo conductivities (both σ(xx) and Hall σ(xy)). As long as valley degeneracy is maintained, the obtained critical conductivity σ(xx) =/~ 1.4e(2)/h is robust upon an increase in disorder (by almost 1 order of magnitude) and magnetic fields ranging from about 2 to 200 T. When the sublattice symmetry is broken, σ(xx) eventually vanishes at the Dirac point owing to localization effects, whereas the critical conductivities of pseudospin-split states (dictating the width of a σ(xy) = 0 plateau) change to σ(xx) =/~ e(2)/h, regardless of the splitting strength, superimposed disorder, or magnetic strength. These findings point towards the nondissipative nature of the quantum Hall effect in disordered graphene in the presence of Landau level splitting.

Efficient solar-to-fuels production from a hybrid microbial-water-splitting catalyst system.

PubMed

Torella, Joseph P; Gagliardi, Christopher J; Chen, Janice S; Bediako, D Kwabena; Colón, Brendan; Way, Jeffery C; Silver, Pamela A; Nocera, Daniel G

2015-02-24

Photovoltaic cells have considerable potential to satisfy future renewable-energy needs, but efficient and scalable methods of storing the intermittent electricity they produce are required for the large-scale implementation of solar energy. Current solar-to-fuels storage cycles based on water splitting produce hydrogen and oxygen, which are attractive fuels in principle but confront practical limitations from the current energy infrastructure that is based on liquid fuels. In this work, we report the development of a scalable, integrated bioelectrochemical system in which the bacterium Ralstonia eutropha is used to efficiently convert CO2, along with H2 and O2 produced from water splitting, into biomass and fusel alcohols. Water-splitting catalysis was performed using catalysts that are made of earth-abundant metals and enable low overpotential water splitting. In this integrated setup, equivalent solar-to-biomass yields of up to 3.2% of the thermodynamic maximum exceed that of most terrestrial plants. Moreover, engineering of R. eutropha enabled production of the fusel alcohol isopropanol at up to 216 mg/L, the highest bioelectrochemical fuel yield yet reported by >300%. This work demonstrates that catalysts of biotic and abiotic origin can be interfaced to achieve challenging chemical energy-to-fuels transformations.

An Inexpensive Co-Intercalated Layered Double Hydroxide Composite with Electron Donor-Acceptor Character for Photoelectrochemical Water Splitting

PubMed Central

Zheng, Shufang; Lu, Jun; Yan, Dongpeng; Qin, Yumei; Li, Hailong; Evans, David G.; Duan, Xue

2015-01-01

In this paper, the inexpensive 4,4-diaminostilbene-2,2-disulfonate (DAS) and 4,4-dinitro-stilbene-2,2- disulfonate (DNS) anions with arbitrary molar ratios were successfully co-intercalated into Zn2Al-layered double hydroxides (LDHs). The DAS(50%)-DNS/LDHs composite exhibited the broad UV-visible light absorption and fluorescence quenching, which was a direct indication of photo-induced electron transfer (PET) process between the intercalated DAS (donor) and DNS (acceptor) anions. This was confirmed by the matched HOMO/LUMO energy levels alignment of the intercalated DAS and DNS anions, which was also compatible for water splitting. The DAS(50%)-DNS/LDHs composite was fabricated as the photoanode and Pt as the cathode. Under the UV-visible light illumination, the enhanced photo-generated current (4.67 mA/cm2 at 0.8 V vs. SCE) was generated in the external circuit, and the photoelectrochemical water split was realized. Furthermore, this photoelectrochemical water splitting performance had excellent crystalline, electrochemical and optical stability. Therefore, this novel inorganic/organic hybrid photoanode exhibited potential application prospect in photoelectrochemical water splitting. PMID:26174201

Giant Rashba splitting in 2D organic-inorganic halide perovskites measured by transient spectroscopies

DOE PAGES

Zhai, Yaxin; Baniya, Sangita; Zhang, Chuang; ...

2017-07-28

Two-dimensional (2D) layered hybrid organic-inorganic halide perovskite semiconductors form natural “multiple quantum wells” that have strong spin-orbit coupling due to the heavy elements in their building blocks. This may lead to “Rashba splitting” close to the extrema in the electron bands. We have used a plethora of ultrafast transient, nonlinear optical spectroscopies and theoretical calculations to study the primary (excitons) and long-lived (free carriers) photoexcitations in thin films of 2D perovskite, namely, (C 6H 5C 2H 4NH 3) 2PbI 4. The density functional theory calculation shows the occurrence of Rashba splitting in the plane perpendicular to the 2D barrier. Frommore » the electroabsorption spectrum and photoinduced absorption spectra from excitons and free carriers, we obtain a giant Rashba splitting in this compound, with energy splitting of (40 ± 5) meV and Rashba parameter of (1.6 ± 0.1) eV·Å, which are among the highest Rashba splitting size parameters reported so far. In conclusion, this finding shows that 2D hybrid perovskites have great promise for potential applications in spintronics.« less

Shear-wave splitting and moonquakes

NASA Astrophysics Data System (ADS)

Dimech, J. L.; Weber, R. C.; Savage, M. K.

2017-12-01

Shear-wave splitting is a powerful tool for measuring anisotropy in the Earth's crust and mantle, and is sensitive to geological features such as fluid filled cracks, thin alternating layers of rock with different elastic properties, and preferred mineral orientations caused by strain. Since a shear wave splitting measurement requires only a single 3-component seismic station, it has potential applications for future single-station planetary seismic missions, such as the InSight geophysical mission to Mars, as well as possible future missions to Europa and the Moon. Here we present a preliminary shear-wave splitting analysis of moonquakes detected by the Apollo Passive Seismic Experiment. Lunar seismic data suffers from several drawbacks compared to modern terrestrial data, including severe seismic scattering, low intrinsic attenuation, 10-bit data resolution, thermal spikes, and timing errors. Despite these drawbacks, we show that it is in principle possible to make a shear wave splitting measurement using the S-phase arrival of a relatively high-quality moonquake, as determined by several agreeing measurement criteria. Encouraged by this finding, we further extend our analysis to clusters of "deep moonquake" events by stacking multiple events from the same cluster together to further enhance the quality of the S-phase arrivals that the measurement is based on.

Novel Split Chest Tube Improves Post-Surgical Thoracic Drainage

PubMed Central

Olivencia-Yurvati, Albert H; Cherry, Brandon H; Gurji, Hunaid A; White, Daniel W; Newton, J Tyler; Scott, Gary F; Hoxha, Besim; Gourlay, Terence; Mallet, Robert T

2014-01-01

Objective Conventional, separate mediastinal and pleural tubes are often inefficient at draining thoracic effusions. Description We developed a Y-shaped chest tube with split ends that divide within the thoracic cavity, permitting separate intrathoracic placement and requiring a single exit port. In this study, thoracic drainage by the split drain vs. that of separate drains was tested. Methods After sternotomy, pericardiotomy, and left pleurotomy, pigs were fitted with separate chest drains (n=10) or a split tube prototype (n=9) with internal openings positioned in the mediastinum and in the costo-diaphragmatic recess. Separate series of experiments were conducted to test drainage of D5W or 0.58 M sucrose, an aqueous solution with viscosity approximating that of plasma. One litre of fluid was infused into the thorax, and suction was applied at −20 cm H2O for 30 min. Results When D5W was infused, the split drain left a residual volume of 53 ± 99 ml (mean value ± SD) vs. 148 ± 120 for the separate drain (P=0.007), representing a drainage efficiency (i.e. drained vol/[drained + residual vol]) of 95 ± 10% vs. 86 ± 12% for the separate drains (P = 0.011). In the second series, the split drain evacuated more 0.58 M sucrose in the first minute (967 ± 129 ml) than the separate drains (680 ± 192 ml, P<0.001). By 30 min, the split drain evacuated a similar volume of sucrose vs. the conventional drain (1089 ± 72 vs. 1056 ± 78 ml; P = 0.5). Residual volume tended to be lower (25 ± 10 vs. 62 ± 72 ml; P = 0.128) and drainage efficiency tended to be higher (98 ± 1 vs. 95 ± 6%; P = 0.111) with the split drain vs. conventional separate drains. Conclusion The split chest tube drained the thoracic cavity at least as effectively as conventional separate tubes. This new device could potentially alleviate postoperative complications. PMID:25478289

Novel Split Chest Tube Improves Post-Surgical Thoracic Drainage.

PubMed

Olivencia-Yurvati, Albert H; Cherry, Brandon H; Gurji, Hunaid A; White, Daniel W; Newton, J Tyler; Scott, Gary F; Hoxha, Besim; Gourlay, Terence; Mallet, Robert T

2014-01-01

Conventional, separate mediastinal and pleural tubes are often inefficient at draining thoracic effusions. We developed a Y-shaped chest tube with split ends that divide within the thoracic cavity, permitting separate intrathoracic placement and requiring a single exit port. In this study, thoracic drainage by the split drain vs. that of separate drains was tested. After sternotomy, pericardiotomy, and left pleurotomy, pigs were fitted with separate chest drains (n=10) or a split tube prototype (n=9) with internal openings positioned in the mediastinum and in the costo-diaphragmatic recess. Separate series of experiments were conducted to test drainage of D5W or 0.58 M sucrose, an aqueous solution with viscosity approximating that of plasma. One litre of fluid was infused into the thorax, and suction was applied at -20 cm H2O for 30 min. When D5W was infused, the split drain left a residual volume of 53 ± 99 ml (mean value ± SD) vs. 148 ± 120 for the separate drain (P=0.007), representing a drainage efficiency (i.e. drained vol/[drained + residual vol]) of 95 ± 10% vs. 86 ± 12% for the separate drains (P = 0.011). In the second series, the split drain evacuated more 0.58 M sucrose in the first minute (967 ± 129 ml) than the separate drains (680 ± 192 ml, P<0.001). By 30 min, the split drain evacuated a similar volume of sucrose vs. the conventional drain (1089 ± 72 vs. 1056 ± 78 ml; P = 0.5). Residual volume tended to be lower (25 ± 10 vs. 62 ± 72 ml; P = 0.128) and drainage efficiency tended to be higher (98 ± 1 vs. 95 ± 6%; P = 0.111) with the split drain vs. conventional separate drains. The split chest tube drained the thoracic cavity at least as effectively as conventional separate tubes. This new device could potentially alleviate postoperative complications.

Polyaniline as a new type of hole-transporting material to significantly increase the solar water splitting performance of BiVO4 photoanodes

NASA Astrophysics Data System (ADS)

Wang, Xiaojun; Ye, Kai-Hang; Yu, Xiang; Zhu, Jiaqian; Zhu, Yi; Zhang, Yuanming

2018-07-01

Polyaniline (PANI), with its low cost, chemical stability and high conductivity, is used as a hole transporting layer to fabricate NiOOH/PANI/BiVO4 (NPB) photoanode, of which the photoelectrochemical (PEC) water splitting performance is significantly enhanced. The remarkable water oxidation photocurrent of NPB photoanode achieves 3.31 mA cm-2 at 1.23 V vs. RHE under AM 1.5G solar light irradiation, which is greatly increased compared with that of pristine BiVO4 (0.89 mA cm-2 under the same condition). The maximal incident photon-to-current conversion efficiency achieves 83.3% at 430 nm at 1.23 V vs. RHE and the maximal applied bias photo-to-current efficiency reaches 1.20% at 0.68 V vs. RHE, which are nearly five and ten times higher than that of pristine BiVO4 photoanode, respectively. This NPB photoanode exhibits excellent stability with about 97.22% Faraday efficiency after PEC water splitting for 3 h. The exciting results demonstrate that PANI shows great potential as a hole-transporting layer for photoanode and NPB is an efficient and stable photoanode material with a great potential application in PEC water splitting. Overall, this work provides an excellent reference on designing and fabricating photoanode materials for the future.

Towards black-box calculations of tunneling splittings obtained from vibrational structure methods based on normal coordinates.

PubMed

Neff, Michael; Rauhut, Guntram

2014-02-05

Multidimensional potential energy surfaces obtained from explicitly correlated coupled-cluster calculations and further corrections for high-order correlation contributions, scalar relativistic effects and core-correlation energy contributions were generated in a fully automated fashion for the double-minimum benchmark systems OH3(+) and NH3. The black-box generation of the potentials is based on normal coordinates, which were used in the underlying multimode expansions of the potentials and the μ-tensor within the Watson operator. Normal coordinates are not the optimal choice for describing double-minimum potentials and the question remains if they can be used for accurate calculations at all. However, their unique definition is an appealing feature, which removes remaining errors in truncated potential expansions arising from different choices of curvilinear coordinate systems. Fully automated calculations are presented, which demonstrate, that the proposed scheme allows for the determination of energy levels and tunneling splittings as a routine application. Copyright © 2013 Elsevier B.V. All rights reserved.

A novel model incorporating two variability sources for describing motor evoked potentials

PubMed Central

Goetz, Stefan M.; Luber, Bruce; Lisanby, Sarah H.; Peterchev, Angel V.

2014-01-01

Objective Motor evoked potentials (MEPs) play a pivotal role in transcranial magnetic stimulation (TMS), e.g., for determining the motor threshold and probing cortical excitability. Sampled across the range of stimulation strengths, MEPs outline an input–output (IO) curve, which is often used to characterize the corticospinal tract. More detailed understanding of the signal generation and variability of MEPs would provide insight into the underlying physiology and aid correct statistical treatment of MEP data. Methods A novel regression model is tested using measured IO data of twelve subjects. The model splits MEP variability into two independent contributions, acting on both sides of a strong sigmoidal nonlinearity that represents neural recruitment. Traditional sigmoidal regression with a single variability source after the nonlinearity is used for comparison. Results The distribution of MEP amplitudes varied across different stimulation strengths, violating statistical assumptions in traditional regression models. In contrast to the conventional regression model, the dual variability source model better described the IO characteristics including phenomena such as changing distribution spread and skewness along the IO curve. Conclusions MEP variability is best described by two sources that most likely separate variability in the initial excitation process from effects occurring later on. The new model enables more accurate and sensitive estimation of the IO curve characteristics, enhancing its power as a detection tool, and may apply to other brain stimulation modalities. Furthermore, it extracts new information from the IO data concerning the neural variability—information that has previously been treated as noise. PMID:24794287

Hydrogen generation due to water splitting on Si - terminated 4H-Sic(0001) surfaces

NASA Astrophysics Data System (ADS)

Li, Qingfang; Li, Qiqi; Yang, Cuihong; Rao, Weifeng

2018-02-01

The chemical reactions of hydrogen gas generation via water splitting on Si-terminated 4H-SiC surfaces with or without C/Si vacancies were studied by using first-principles. We studied the reaction mechanisms of hydrogen generation on the 4H-SiC(0001) surface. Our calculations demonstrate that there are major rearrangements in surface when H2O approaches the SiC(0001) surface. The first H splitting from water can occur with ground-state electronic structures. The second H splitting involves an energy barrier of 0.65 eV. However, the energy barrier for two H atoms desorbing from the Si-face and forming H2 gas is 3.04 eV. In addition, it is found that C and Si vacancies can form easier in SiC(0001)surfaces than in SiC bulk and nanoribbons. The C/Si vacancies introduced can enhance photocatalytic activities. It is easier to split OH on SiC(0001) surface with vacancies compared to the case of clean SiC surface. H2 can form on the 4H-SiC(0001) surface with C and Si vacancies if the energy barriers of 1.02 and 2.28 eV are surmounted, respectively. Therefore, SiC(0001) surface with C vacancy has potential applications in photocatalytic water-splitting.

Supernova neutrinos and antineutrinos: ternary luminosity diagram and spectral split patterns

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

Fogli, Gianluigi; Marrone, Antonio; Tamborra, Irene

2009-10-01

In core-collapse supernovae, the ν{sub e} and ν-bar {sub e} species may experience collective flavor swaps to non-electron species ν{sub x}, within energy intervals limited by relatively sharp boundaries (''splits''). These phenomena appear to depend sensitively upon the initial energy spectra and luminosities. We investigate the effect of generic variations of the fractional luminosities (l{sub e}, l{sub ē}, l{sub x}) with respect to the usual ''energy equipartition'' case (1/6, 1/6, 1/6), within an early-time supernova scenario with fixed thermal spectra and total luminosity. We represent the constraint l{sub e}+l{sub ē}+4l{sub x} = 1 in a ternary diagram, which is exploredmore » via numerical experiments (in single-angle approximation) over an evenly-spaced grid of points. In inverted hierarchy, single splits arise in most cases, but an abrupt transition to double splits is observed for a few points surrounding the equipartition one. In normal hierarchy, collective effects turn out to be unobservable at all grid points but one, where single splits occur. Admissible deviations from equipartition may thus induce dramatic changes in the shape of supernova (anti)neutrino spectra. The observed patterns are interpreted in terms of initial flavor polarization vectors (defining boundaries for the single/double split transitions), lepton number conservation, and minimization of potential energy.« less

Optimizing ELISAs for precision and robustness using laboratory automation and statistical design of experiments.

PubMed

Joelsson, Daniel; Moravec, Phil; Troutman, Matthew; Pigeon, Joseph; DePhillips, Pete

2008-08-20

Transferring manual ELISAs to automated platforms requires optimizing the assays for each particular robotic platform. These optimization experiments are often time consuming and difficult to perform using a traditional one-factor-at-a-time strategy. In this manuscript we describe the development of an automated process using statistical design of experiments (DOE) to quickly optimize immunoassays for precision and robustness on the Tecan EVO liquid handler. By using fractional factorials and a split-plot design, five incubation time variables and four reagent concentration variables can be optimized in a short period of time.

[Alcohol consumption and positive alcohol expectancies in young adults: a typological approach using TwoStep cluster].

PubMed

Vautier, S; Jmel, S; Fourio, C; Moncany, D

2007-09-01

The present study investigates the heterogeneity of the population of young adult drinkers with respect to alcohol consumption and Positive Alcohol Expectancies (PAEs). Based on the positive relationship between both kinds of variables, PAE is commonly viewed as a potential motivational factor of alcoholic addiction. Empirical analyses based on the regression of alcohol consumption on PAEs suppose that the observations are statistically homogeneous with respect to the level of alcohol consumption, however. We explored the existence of moderate drinkers with a high PAE profile, and abusive drinkers with a low PAE profile. 1,017 young adult drinkers, mean age=23 +/- 2.84, with various educational levels, comprising 506 males and 511 females, were recruited as voluntary participants in a survey by undergraduate psychology students from the University of Toulouse Le Mirail. They completed a French version of the Alcohol Use Disorders Identifiction Test (AUDIT) and a French adaptation of the Alcohol Expectancy Questionnaire (AEQ). Three levels of alcohol consumption were defined using the AUDIT score, and six composite scores were obtained by averaging the relevant item-scores from the AEQ. The AEQ scores were interpreted as measurement of six kinds of PAEs, namely Global positive change, Sexual enhancement, Social and physical pleasure, Social assertiveness, Relaxation, and Arousal/Power. The TwoStep cluster methodology was used to explore the data. This methodology is convenient to deal with a mix of quantitative and qualitative variables, and it provides a classification model which is optimized through the use of an information criterion as Schwarz's Bayesian Information Criterion (BIC). The automatic clustering suggested five clusters, whose stability was ascertained until 75% of the sample size. Low drinkers (n=527) were split into one cluster of low PAEs (I1) and, interestingly, one cluster of high PAEs (I3, 46%). High drinkers (n=344) were split into one cluster of intermediate PAEs (II4) and one cluster of high PAEs (II5, 52%). Interestingly again, abusive drinkers (n=146) remained a single group (III2), exhibiting high PAEs. Clusters I3 and III3 comprised a significant proportion of males. Constraining the algorithm to find 6 clusters did not affect class III2, but split low drinkers into three clusters. Although the present results should be considered cautiously because of the novelty of TwoStep cluster methodology, they suggest a group of moderate drinkers with high PAEs. Also, abusive drinkers express high PAEs (except for 2 cases). Statistical homogeneity of moderate drinkers with respect to PAE variables appears as a dubious assumption.

A Work in Progress: The United Kingdom’s Campaign Against Radicalization

DTIC Science & Technology

2007-02-01

See: http://www.statistics.gov.uk/cci/ nugget.asp?id=293. 22 Alexandra Frean and Rajeev Syal , “Muslim Britain Split Over Martyrs of 7/7”, Times...Economist, 19 August 2006, pp. 10 – 11. 29 Frean and Syal , op cit. 30 See Petter Nesser, “Post-millennium patterns of Jihadist terrorism in Western Europe

A new model of physical evolution of Jupiter-family comets

NASA Astrophysics Data System (ADS)

Rickman, H.; Szutowicz, S.; Wójcikowski, K.

2014-07-01

We aim to find the statistical physical lifetimes of Jupiter Family comets. For this purpose, we try to model the processes that govern the dynamical and physical evolution of comets. We pay special attention to physical evolution; attempts at such modelling have been made before, but we propose a more accurate model, which will include more physical effects. The model is tested on a sample of fictitious comets based on real Jupiter Family comets with some orbital elements changed to a state before the capture by Jupiter. We model four different physical effects: erosion by sublimation, dust mantling, rejuvenation (mantle blow-off), and splitting. While for sublimation and splitting there already are some models, like di Sisto et. al. (2009), and we only wish to make them more accurate, dust mantling and rejuvenation have not been included in previous, statistical physical evolution models. Each of these effects depends on one or more tunable parameters, which we establish by choosing the model that best fits the observed comet sample in a way similar to di Sisto et. al. (2009). In contrast to di Sisto et. al., our comparison also involves the observed active fractions vs. nuclear radii.

Sample size determination in combinatorial chemistry.

PubMed Central

Zhao, P L; Zambias, R; Bolognese, J A; Boulton, D; Chapman, K

1995-01-01

Combinatorial chemistry is gaining wide appeal as a technique for generating molecular diversity. Among the many combinatorial protocols, the split/recombine method is quite popular and particularly efficient at generating large libraries of compounds. In this process, polymer beads are equally divided into a series of pools and each pool is treated with a unique fragment; then the beads are recombined, mixed to uniformity, and redivided equally into a new series of pools for the subsequent couplings. The deviation from the ideal equimolar distribution of the final products is assessed by a special overall relative error, which is shown to be related to the Pearson statistic. Although the split/recombine sampling scheme is quite different from those used in analysis of categorical data, the Pearson statistic is shown to still follow a chi2 distribution. This result allows us to derive the required number of beads such that, with 99% confidence, the overall relative error is controlled to be less than a pregiven tolerable limit L1. In this paper, we also discuss another criterion, which determines the required number of beads so that, with 99% confidence, all individual relative errors are controlled to be less than a pregiven tolerable limit L2 (0 < L2 < 1). PMID:11607586

Growth of p-type hematite by atomic layer deposition and its utilization for improved solar water splitting.

PubMed

Lin, Yongjing; Xu, Yang; Mayer, Matthew T; Simpson, Zachary I; McMahon, Gregory; Zhou, Sa; Wang, Dunwei

2012-03-28

Mg-doped hematite (α-Fe(2)O(3)) was synthesized by atomic layer deposition (ALD). The resulting material was identified as p-type with a hole concentration of ca. 1.7 × 10(15) cm(-3). When grown on n-type hematite, the p-type layer was found to create a built-in field that could be used to assist photoelectrochemical water splitting reactions. A nominal 200 mV turn-on voltage shift toward the cathodic direction was measured, which is comparable to what has been measured using water oxidation catalysts. This result suggests that it is possible to achieve desired energetics for solar water splitting directly on metal oxides through advanced material preparations. Similar approaches may be used to mitigate problems caused by energy mismatch between water redox potentials and the band edges of hematite and many other low-cost metal oxides, enabling practical solar water splitting as a means for solar energy storage.

Solar water splitting by photovoltaic-electrolysis with a solar-to-hydrogen efficiency over 30%

PubMed Central

Jia, Jieyang; Seitz, Linsey C.; Benck, Jesse D.; Huo, Yijie; Chen, Yusi; Ng, Jia Wei Desmond; Bilir, Taner; Harris, James S.; Jaramillo, Thomas F.

2016-01-01

Hydrogen production via electrochemical water splitting is a promising approach for storing solar energy. For this technology to be economically competitive, it is critical to develop water splitting systems with high solar-to-hydrogen (STH) efficiencies. Here we report a photovoltaic-electrolysis system with the highest STH efficiency for any water splitting technology to date, to the best of our knowledge. Our system consists of two polymer electrolyte membrane electrolysers in series with one InGaP/GaAs/GaInNAsSb triple-junction solar cell, which produces a large-enough voltage to drive both electrolysers with no additional energy input. The solar concentration is adjusted such that the maximum power point of the photovoltaic is well matched to the operating capacity of the electrolysers to optimize the system efficiency. The system achieves a 48-h average STH efficiency of 30%. These results demonstrate the potential of photovoltaic-electrolysis systems for cost-effective solar energy storage. PMID:27796309

Policy options for the split incentive: Increasing energy efficiency for low-income renters.

PubMed

Bird, Stephen; Hernández, Diana

2012-09-01

The split incentive problem concerns the lack of appropriate incentives to implement energy efficiency measures. In particular, low income tenants face a phenomenon of energy poverty in which they allocate significantly more of their household income to energy expenditures than other renters. This problem is substantial, affecting 1.89% of all United States' energy use. If effectively addressed, it would create a range of savings between 4 and 11 billion dollars per year for many of the nation's poorest residents. We argue that a carefully designed program of incentives for participants (including landlords) in conjunction with a unique type of utility-managed on-bill financing mechanism has significant potential to solve many of the complications. We focus on three kinds of split incentives, five concerns inherent to addressing split incentive problems (scale, endurance, incentives, savings, political disfavor), and provide a detailed policy proposal designed to surpass those problems, with a particular focus on low-income tenants in a U.S.

Ab Initio Vibrational Levels For HO2 and Vibrational Splittings for Hydrogen Atom Transfer

NASA Technical Reports Server (NTRS)

Barclay, V. J.; Dateo, Christopher E.; Hamilton, I. P.; Arnold, James O. (Technical Monitor)

1994-01-01

We calculate vibrational levels and wave functions for HO2 using the recently reported ab initio potential energy surface of Walch and Duchovic. There is intramolecular hydrogen atom transfer when the hydrogen atom tunnels through a T-shaped saddle point separating two equivalent equilibrium geometries, and correspondingly, the energy levels are split. We focus on vibrational levels and wave functions with significant splitting. The first three vibrational levels with splitting greater than 2/cm are (15 0), (0 7 1) and (0 8 0) where V(sub 2) is the O-O-H bend quantum number. We discuss the dynamics of hydrogen atom transfer; in particular, the O-O distances at which hydrogen atom transfer is most probable for these vibrational levels. The material of the proposed presentation was reviewed and the technical content will not reveal any information not already in the public domain and will not give any foreign industry or government a competitive advantage.

Solar water splitting by photovoltaic-electrolysis with a solar-to-hydrogen efficiency over 30.

PubMed

Jia, Jieyang; Seitz, Linsey C; Benck, Jesse D; Huo, Yijie; Chen, Yusi; Ng, Jia Wei Desmond; Bilir, Taner; Harris, James S; Jaramillo, Thomas F

2016-10-31

Hydrogen production via electrochemical water splitting is a promising approach for storing solar energy. For this technology to be economically competitive, it is critical to develop water splitting systems with high solar-to-hydrogen (STH) efficiencies. Here we report a photovoltaic-electrolysis system with the highest STH efficiency for any water splitting technology to date, to the best of our knowledge. Our system consists of two polymer electrolyte membrane electrolysers in series with one InGaP/GaAs/GaInNAsSb triple-junction solar cell, which produces a large-enough voltage to drive both electrolysers with no additional energy input. The solar concentration is adjusted such that the maximum power point of the photovoltaic is well matched to the operating capacity of the electrolysers to optimize the system efficiency. The system achieves a 48-h average STH efficiency of 30%. These results demonstrate the potential of photovoltaic-electrolysis systems for cost-effective solar energy storage.

Policy options for the split incentive: Increasing energy efficiency for low-income renters

PubMed Central

Bird, Stephen; Hernández, Diana

2016-01-01

The split incentive problem concerns the lack of appropriate incentives to implement energy efficiency measures. In particular, low income tenants face a phenomenon of energy poverty in which they allocate significantly more of their household income to energy expenditures than other renters. This problem is substantial, affecting 1.89% of all United States' energy use. If effectively addressed, it would create a range of savings between 4 and 11 billion dollars per year for many of the nation's poorest residents. We argue that a carefully designed program of incentives for participants (including landlords) in conjunction with a unique type of utility-managed on-bill financing mechanism has significant potential to solve many of the complications. We focus on three kinds of split incentives, five concerns inherent to addressing split incentive problems (scale, endurance, incentives, savings, political disfavor), and provide a detailed policy proposal designed to surpass those problems, with a particular focus on low-income tenants in a U.S. context. PMID:27053828

All solution-processed lead halide perovskite-BiVO4 tandem assembly for photolytic solar fuels production.

PubMed

Chen, Yong-Siou; Manser, Joseph S; Kamat, Prashant V

2015-01-21

The quest for economic, large-scale hydrogen production has motivated the search for new materials and device designs capable of splitting water using only energy from the sun. Here we introduce an all solution-processed tandem water splitting assembly composed of a BiVO4 photoanode and a single-junction CH3NH3PbI3 hybrid perovskite solar cell. This unique configuration allows efficient solar photon management, with the metal oxide photoanode selectively harvesting high energy visible photons, and the underlying perovskite solar cell capturing lower energy visible-near IR wavelengths in a single-pass excitation. Operating without external bias under standard AM 1.5G illumination, the photoanode-photovoltaic architecture, in conjunction with an earth-abundant cobalt phosphate catalyst, exhibits a solar-to-hydrogen conversion efficiency of 2.5% at neutral pH. The design of low-cost tandem water splitting assemblies employing single-junction hybrid perovskite materials establishes a potentially promising new frontier for solar water splitting research.

Analysis of progressive damage in thin circular laminates due to static-equivalent impact loads

NASA Technical Reports Server (NTRS)

Shivakumar, K. N.; Elber, W.; Illg, W.

1983-01-01

Clamped circular graphite/epoxy plates (25.4, 38.1, and 50.8 mm radii) with an 8-ply quasi-isotropic layup were analyzed for static-equivalent impact loads using the minimum-total-potential-energy method and the von Karman strain-displacement equations. A step-by-step incremental transverse displacement procedure was used to calculate plate load and ply stresses. The ply failure region was calculated using the Tsai-Wu criterion. The corresponding failure modes (splitting and fiber failure) were determined using the maximum stress criteria. The first-failure mode was splitting and initiated first in the bottom ply. The splitting-failure thresholds were relatively low and tended to be lower for larger plates than for small plates. The splitting-damage region in each ply was elongated in its fiber direction; the bottom ply had the largest damage region. The calculated damage region for the 25.4-mm-radius plate agreed with limited static test results from the literature.

Influence of war on quantitative and qualitative changes in drug-induced mortality in Split-Dalmatia County, Croatia

PubMed Central

Marasović Šušnjara, Ivana; Definis Gojanović, Marija; Vodopija, Davor; Čapkun, Vesna; Smoljanović, Ankica

2011-01-01

Aim To study drug-induced mortality and characteristics of overdose deaths in the war (1991-1995), pre-war (1986-1990), and post-war period (1996-2000) in Split-Dalmatia County. Methods We retrospectively searched through Databases of the Department of Forensic Medicine, University Hospital Split, the national register of death records, the archives of the Split-Dalmatia County Police, and the Register of Treated Drug Addicts of the Croatian National Institute of Public Health, covering the period from 1986 to 2000, according to drug poisoning codes IX and X of the International Classification of Diseases. The indicators were statistically analyzed. Results There were 146 registered drug-induced deaths, with 136 (93%) deceased being men. The median age of all cases was 27 years (interquartile range 8). Most of them were single (70.6%), unemployed (44.6%), and secondary school graduates (69.2%). In the war period, there were 4.8 times more deaths than in the pre-war period (P = 0.014), and in the post-war period there were 5.2 times more deaths than in the pre-war period (P = 0.008). The most common site of death was the deceased person’s home. The toxicological analyses showed that 59 (61%) deaths were heroin related, alcohol use was found in 62 cases (42.5%), and multi-substance use was found in more than a half of the cases. In 133 (91.1%) cases, deaths were classified as unintentional, whereas 13 (8.9%) were classified as suicides. Conclusion The war, along with other risk factors, contributed to unfavorable developments related to drug abuse in Split-Dalmatia County, including the increase in the drug-induced mortality rate. PMID:21990081

Influence of war on quantitative and qualitative changes in drug-induced mortality in Split-Dalmatia County, Croatia.

PubMed

Marasovic Susnjara, Ivana; Definis Gojanovic, Marija; Vodopija, Davor; Capkun, Vesna; Smoljanovic, Ankica

2011-10-15

To study drug-induced mortality and characteristics of overdose deaths in the war (1991-1995), pre-war (1986-1990), and post-war period (1996-2000) in Split-Dalmatia County. We retrospectively searched through Databases of the Department of Forensic Medicine, University Hospital Split, the national register of death records, the archives of the Split-Dalmatia County Police, and the Register of Treated Drug Addicts of the Croatian National Institute of Public Health, covering the period from 1986 to 2000, according to drug poisoning codes IX and X of the International Classification of Diseases. The indicators were statistically analyzed. There were 146 registered drug-induced deaths, with 136 (93%) deceased being men. The median age of all cases was 27 years (interquartile range 8). Most of them were single (70.6%), unemployed (44.6%), and secondary school graduates (69.2%). In the war period, there were 4.8 times more deaths than in the pre-war period (P=0.014), and in the post-war period there were 5.2 times more deaths than in the pre-war period (P=0.008). The most common site of death was the deceased person's home. The toxicological analyses showed that 59 (61%) deaths were heroin related, alcohol use was found in 62 cases (42.5%), and multi-substance use was found in more than a half of the cases. In 133 (91.1%) cases, deaths were classified as unintentional, whereas 13 (8.9%) were classified as suicides. CONCLUSION; The war, along with other risk factors, contributed to unfavorable developments related to drug abuse in Split-Dalmatia County, including the increase in the drug-induced mortality rate.

Slab anisotropy from subduction zone guided waves in Taiwan

NASA Astrophysics Data System (ADS)

Chen, K. H.; Tseng, Y. L.; Hu, J. C.

2014-12-01

Frozen-in anisotropic structure in the oceanic lithosphere and faulting/hydration in the upper layer of the slab are expected to play an important role in anisotropic signature of the subducted slab. Over the past several decades, despite the advances in characterizing anisotropy using shear wave splitting method and its developments, the character of slab anisotropy remains poorly understood. In this study we investigate the slab anisotropy using subduction zone guided waves characterized by long path length in the slab. In the southernmost Ryukyu subduction zone, seismic waves from events deeper than 100 km offshore northern Taiwan reveal wave guide behavior: (1) a low-frequency (< 1 Hz) first arrival recognized on vertical and radial components but not transverse component (2) large, sustained high-frequency (3-10 Hz) signal in P and S wave trains. The depth dependent high-frequency content (3-10Hz) confirms the association with a waveguide effect in the subducting slab rather than localized site amplification effects. Using the selected subduction zone guided wave events, we further analyzed the shear wave splitting for intermediate-depth earthquakes in different frequency bands, to provide the statistically meaningful shear wave splitting parameters. We determine shear wave splitting parameters from the 34 PSP guided events that are deeper than 100 km with ray path traveling along the subducted slab. From shear wave splitting analysis, the slab and crust effects reveal consistent polarization pattern of fast directions of EN-WS and delay time of 0.13 - 0.27 sec. This implies that slab anisotropy is stronger than the crust effect (<0.1 s) but weaker than the mantle wedge and sub-slab mantle effect (0.3-1.3 s) in Taiwan.

Prospective randomized controlled trial: fibrin sealant reduces split skin graft donor-site pain.

PubMed

Healy, Ciaran; Greig, Aina V H; Murphy, Adrian D; Powell, Christopher; Pinder, Richard J; Saour, Samer; Abela, Christopher; Knight, William; Geh, Jenny L C

2013-07-01

Pain at split skin graft donor sites is common. Fibrin sealant has been demonstrated to reduce time to hemostasis at wound sites, and patients receiving this treatment were incidentally noted to report less pain. This study aimed to evaluate pain and incapacity in split skin graft donor sites treated with and without fibrin sealant. Fifty patients requiring thigh donor-site split skin grafts were prospectively randomized to receive either a self-adhesive fabric dressing alone or fibrin sealant plus the self-adhesive fabric dressing as primary donor-site dressings. External secondary dressings were the same. Patients were blinded with regard to treatment group. Using visual analogue scales (scored 0 to 5), patients rated their donor-site pain and incapacity for 14 days postoperatively. Secondary endpoints were length of hospital stay and duration of requirement for dressings. Forty patients were included in the study analysis and completed self-reported pain and incapacity scores. Twenty received the fibrin sealant plus self-adhesive fabric dressing and 20 received the fabric dressing only (controls). Patients using the fibrin sealant plus the dressing reported significantly less pain (mean score, 0.42 versus 1.60, p < 0.001) and significantly less incapacity (mean score, 0.48 versus 1.71, p < 0.001). Patients allocated to the fibrin sealant group recorded shorter lengths of stay and faster time to discontinuation of dressing, though statistical significance was not achieved. Patients whose split skin graft donor sites were dressed with fibrin sealant plus self-adhesive fabric dressing experienced significantly less pain and incapacity than patients with self-adhesive fabric dressings alone, allowing a more rapid return to normal activity. Therapeutic, II.

A genome-wide methylation study on obesity: differential variability and differential methylation.

PubMed

Xu, Xiaojing; Su, Shaoyong; Barnes, Vernon A; De Miguel, Carmen; Pollock, Jennifer; Ownby, Dennis; Shi, Hidong; Zhu, Haidong; Snieder, Harold; Wang, Xiaoling

2013-05-01

Besides differential methylation, DNA methylation variation has recently been proposed and demonstrated to be a potential contributing factor to cancer risk. Here we aim to examine whether differential variability in methylation is also an important feature of obesity, a typical non-malignant common complex disease. We analyzed genome-wide methylation profiles of over 470,000 CpGs in peripheral blood samples from 48 obese and 48 lean African-American youth aged 14-20 y old. A substantial number of differentially variable CpG sites (DVCs), using statistics based on variances, as well as a substantial number of differentially methylated CpG sites (DMCs), using statistics based on means, were identified. Similar to the findings in cancers, DVCs generally exhibited an outlier structure and were more variable in cases than in controls. By randomly splitting the current sample into a discovery and validation set, we observed that both the DVCs and DMCs identified from the first set could independently predict obesity status in the second set. Furthermore, both the genes harboring DMCs and the genes harboring DVCs showed significant enrichment of genes identified by genome-wide association studies on obesity and related diseases, such as hypertension, dyslipidemia, type 2 diabetes and certain types of cancers, supporting their roles in the etiology and pathogenesis of obesity. We generalized the recent finding on methylation variability in cancer research to obesity and demonstrated that differential variability is also an important feature of obesity-related methylation changes. Future studies on the epigenetics of obesity will benefit from both statistics based on means and statistics based on variances.

Detection of membrane protein-protein interaction in planta based on dual-intein-coupled tripartite split-GFP association.

PubMed

Liu, Tzu-Yin; Chou, Wen-Chun; Chen, Wei-Yuan; Chu, Ching-Yi; Dai, Chen-Yi; Wu, Pei-Yu

2018-05-01

Despite the great interest in identifying protein-protein interactions (PPIs) in biological systems, only a few attempts have been made at large-scale PPI screening in planta. Unlike biochemical assays, bimolecular fluorescence complementation allows visualization of transient and weak PPIs in vivo at subcellular resolution. However, when the non-fluorescent fragments are highly expressed, spontaneous and irreversible self-assembly of the split halves can easily generate false positives. The recently developed tripartite split-GFP system was shown to be a reliable PPI reporter in mammalian and yeast cells. In this study, we adapted this methodology, in combination with the β-estradiol-inducible expression cassette, for the detection of membrane PPIs in planta. Using a transient expression assay by agroinfiltration of Nicotiana benthamiana leaves, we demonstrate the utility of the tripartite split-GFP association in plant cells and affirm that the tripartite split-GFP system yields no spurious background signal even with abundant fusion proteins readily accessible to the compartments of interaction. By validating a few of the Arabidopsis PPIs, including the membrane PPIs implicated in phosphate homeostasis, we proved the fidelity of this assay for detection of PPIs in various cellular compartments in planta. Moreover, the technique combining the tripartite split-GFP association and dual-intein-mediated cleavage of polyprotein precursor is feasible in stably transformed Arabidopsis plants. Our results provide a proof-of-concept implementation of the tripartite split-GFP system as a potential tool for membrane PPI screens in planta. © 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Ltd.

Covalent surface modification of gallium arsenide photocathodes for water splitting in highly acidic electrolyte

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

Garner, Logan E.; Steirer, K. Xerxes; Young, James L.

Efficient water splitting using light as the only energy input requires stable semiconductor electrodes with favorable energetics for the water-oxidation and proton-reduction reactions. Strategies to tune electrode potentials using molecular dipoles adsorbed to the semiconductor surface have been pursued for decades but are often based on weak interactions and quickly react to desorb the molecule under conditions relevant to sustained photoelectrolysis. Here, we show that covalent attachment of fluorinated, aromatic molecules to p-GaAs(1 0 0) surfaces can be employed to tune the photocurrent onset potentials of p-GaAs(1 0 0) photocathodes and reduce the external energy required for water splitting. Resultsmore » indicate that initial photocurrent onset potentials can be shifted by nearly 150 mV in pH -0.5 electrolyte under 1 Sun (1000 W m -2) illumination resulting from the covalently bound surface dipole. Furthermore, X-ray photoelectron spectroscopy analysis reveals that the covalent molecular dipole attachment is not robust under extended 50 h photoelectrolysis, the modified surface delays arsenic oxide formation that results in a p-GaAs(1 0 0) photoelectrode operating at a sustained photocurrent density of -20.5 mA cm -2 within -0.5 V of the reversible hydrogen electrode.« less

Covalent surface modification of gallium arsenide photocathodes for water splitting in highly acidic electrolyte

DOE PAGES

Garner, Logan E.; Steirer, K. Xerxes; Young, James L.; ...

2016-12-12

Efficient water splitting using light as the only energy input requires stable semiconductor electrodes with favorable energetics for the water-oxidation and proton-reduction reactions. Strategies to tune electrode potentials using molecular dipoles adsorbed to the semiconductor surface have been pursued for decades but are often based on weak interactions and quickly react to desorb the molecule under conditions relevant to sustained photoelectrolysis. Here, we show that covalent attachment of fluorinated, aromatic molecules to p-GaAs(1 0 0) surfaces can be employed to tune the photocurrent onset potentials of p-GaAs(1 0 0) photocathodes and reduce the external energy required for water splitting. Resultsmore » indicate that initial photocurrent onset potentials can be shifted by nearly 150 mV in pH -0.5 electrolyte under 1 Sun (1000 W m -2) illumination resulting from the covalently bound surface dipole. Furthermore, X-ray photoelectron spectroscopy analysis reveals that the covalent molecular dipole attachment is not robust under extended 50 h photoelectrolysis, the modified surface delays arsenic oxide formation that results in a p-GaAs(1 0 0) photoelectrode operating at a sustained photocurrent density of -20.5 mA cm -2 within -0.5 V of the reversible hydrogen electrode.« less

Clinical potential of a silk sericin-releasing bioactive wound dressing for the treatment of split-thickness skin graft donor sites.

PubMed

Siritientong, Tippawan; Angspatt, Apichai; Ratanavaraporn, Juthamas; Aramwit, Pornanong

2014-01-01

An ethyl alcohol-precipitated silk sericin/PVA scaffold that controlled the release of silk sericin was previously developed and applied for the treatment of full-thickness wounds in rats and demonstrated efficient healing. In this study, we aimed to further evaluate the clinical potential of this scaffold, hereafter called "silk sericin-releasing wound dressing", for the treatment of split-thickness skin graft donor sites by comparison with the clinically available wound dressing known as "Bactigras®". In vitro characterization and in vivo evaluation for safety of the wound dressings were performed. A clinical trial of the wound dressings was conducted according to standard protocols. The sericin released from the wound dressing was not toxic to HaCat human keratinocytes. A peel test indicated that the silk sericin-releasing wound dressing was less adhesive than Bactigras®, potentially reducing trauma and the risk of repeated injury upon removal. There was no evidence of skin irritation upon treatment with either wound dressing. When tested in patients with split-thickness skin graft donor sites, the wounds treated with the silk sericin-releasing wound dressing exhibited complete healing at 12 ± 5.0 days, whereas those treated with Bactigras® were completely healed at 14 ± 5.2 days (p = 1.99 × 10(-4)). In addition, treatment with the silk sericin-releasing wound dressing significantly reduced pain compared with Bactigras® particularly during the first 4 postoperative days (p = 2.70 × 10(-5) on day 1). We introduce this novel silk sericin-releasing wound dressing as an alternative treatment for split-thickness skin graft donor sites.

Raman spectroscopy for the analytical quality control of low-dose break-scored tablets.

PubMed

Gómez, Diego A; Coello, Jordi; Maspoch, Santiago

2016-05-30

Quality control of solid dosage forms involves the analysis of end products according to well-defined criteria, including the assessment of the uniformity of dosage units (UDU). However, in the case of break-scored tablets, given that tablet splitting is widespread as a means to adjust doses, the uniform distribution of the active pharmaceutical ingredient (API) in all the possible fractions of the tablet must be assessed. A general procedure to accomplish with both issues, using Raman spectroscopy, is presented. It is based on the acquisition of a collection of spectra in different regions of the tablet, that later can be selected to determine the amount of API in the potential fractions that can result after splitting. The procedure has been applied to two commercial products, Sintrom 1 and Sintrom 4, with API (acenocoumarol) mass proportion of 2% and 0.7% respectively. Partial Least Squares (PLS) calibration models were constructed for the quantification of acenocoumarol in whole tablets using HPLC as a reference analytical method. Once validated, the calibration models were used to determine the API content in the different potential fragments of the scored Sintrom 4 tablets. Fragment mass measurements were also performed to estimate the range of masses of the halves and quarters that could result after tablet splitting. The results show that Raman spectroscopy can be an alternative analytical procedure to assess the uniformity of content, both in whole tablets as in its potential fragments, and that Sintrom 4 tablets can be perfectly split in halves, but some cautions have to be taken when considering the fragmentation in quarters. A practical alternative to the use of UDU test for the assessment of tablet fragments is proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

Alternative Refrigerant Evaluation for High-Ambient-Temperature Environments: R-22 and R-410A Alternatives for Mini-Split Air Conditioners

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

Abdelaziz, Omar; Shrestha, Som S.; Munk, Jeffrey D.

The Oak Ridge National Laboratory (ORNL) High-Ambient-Temperature Evaluation Program for low– global warming potential (Low-GWP) Refrigerants aims to develop an understanding of the performance of low-GWP alternative refrigerants to hydrochlorofluorocarbon (HCFC) and hydrofluorocarbon (HFC) refrigerants in mini-split air conditioners under high-ambient-temperature conditions. This final report describes the parties involved, the alternative refrigerant selection process, the test procedures, and the final results.

Alternative Refrigerant Evaluation for High-Ambient Temperature Environments: R-22 and R-410A Alternatives for Mini-Split Air Conditioners

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

Abdelaziz, Omar; Munk, Jeffrey D.; Shrestha, Som S.

The Oak Ridge National Laboratory (ORNL) High-Ambient Temperature Testing Program for Low-GWP Refrigerants aims to develop an understanding of the performance of low-Global Warming Potential (low-GWP) alternatives to Hydrochlorofluorocarbon (HCFC) and Hydrofluorocarbon (HFC) refrigerants in mini-split air conditioners under high ambient temperature conditions. This interim working paper describes the parties involved, the alternative refrigerants selection process, the test procedures, and the preliminary results.

Safety and immunogenicity of adjuvanted inactivated split-virion and whole-virion influenza A (H5N1) vaccines in children: a phase I-II randomized trial.

PubMed

Wu, Jiang; Liu, Shu-Zhen; Dong, Shan-Shan; Dong, Xiao-Ping; Zhang, Wu-Li; Lu, Min; Li, Chang-Gui; Zhou, Ji-Chen; Fang, Han-Hua; Liu, Yan; Liu, Li-Ying; Qiu, Yuan-Zheng; Gao, Qiang; Zhang, Xiao-Mei; Chen, Jiang-Ting; Zhong, Xiang; Yin, Wei-Dong; Feng, Zi-Jian

2010-08-31

Highly pathogenic avian influenza A virus H5N1 has the potential to cause a pandemic. Many prototype pandemic influenza A (H5N1) vaccines had been developed and well evaluated in adults in recent years. However, data in children are limited. Herein we evaluate the safety and immunogenicity of adjuvanted split-virion and whole-virion H5N1 vaccines in children. An open-labelled phase I trial was conducted in children aged 3-11 years to receive aluminum-adjuvated, split-virion H5N1 vaccine (5-30 microg) and in children aged 12-17 years to receive aluminum-adjuvated, whole-virion H5N1 vaccine (5-15 microg). Safety of the two formulations was assessed. Then a randomized phase II trial was conducted, in which 141 children aged 3-11 years received the split-virion vaccine (10 or 15 microg) and 280 children aged 12-17 years received the split-virion vaccine (10-30 microg) or the whole-virion vaccine (5 microg). Serum samples were collected for hemagglutination-inhibition (HI) assays. 5-15 microg adjuvated split-virion vaccines were well tolerated in children aged 3-11 years and 5-30 microg adjuvated split-virion vaccines and 5 microg adjuvated whole-virion vaccine were well tolerated in children aged 12-17 years. Most local and systemic reactions were mild or moderate. Before vaccination, all participants were immunologically naïve to H5N1 virus. Immune responses were induced after the first dose and significantly boosted after the second dose. In 3-11 years children, the 10 and 15 microg split-virion vaccine induced similar responses with 55% seroconversion and seroprotection (HI titer >or=1:40) rates. In 12-17 years children, the 30 microg split-virion vaccine induced the highest immune response with 71% seroconversion and seroprotection rates. The 5 microg whole-virion vaccine induced higher response than the 10 microg split-virion vaccine did. The aluminum-adjuvanted, split-virion prototype pandemic influenza A (H5N1) vaccine showed good safety and immunogenicity in children and 30 microg dose induced immune response complying with European Union licensure criteria. (c) 2010 Elsevier Ltd. All rights reserved.

Clinical evaluation of subepithelial connective tissue graft and guided tissue regeneration for treatment of Miller’s class 1 gingival recession (comparative, split mouth, six months study)

PubMed Central

Bhavsar, Neeta-V.; Dulani, Kirti; Trivedi, Rahul

2014-01-01

Objectives: The present study aims to clinically compare and evaluate subepithelial connective tissue graft and the GTR based root coverage in treatment of Miller’s Class I gingival recession. Study Design: 30 patients with at least one pair of Miller’s Class I gingival recession were treated either with Subepithelial connective tissue graft (Group A) or Guided tissue regeneration (Group B). Clinical parameters monitored included recession RD, width of keratinized gingiva (KG), probing depth (PD), clinical attachment level (CAL), attached gingiva (AG), residual probing depth (RPD) and % of Root coverage(%RC). Measurements were taken at baseline, three months and six months. A standard surgical procedure was used for both Group A and Group B. Data were recorded and statistical analysis was done for both intergroup and intragroup. Results: At end of six months % RC obtained were 84.47% (Group A) and 81.67% (Group B). Both treatments resulted in statistically significant improvement in clinical parameters. When compared, no statistically significant difference was found between both groups except in RPD, where it was significantly greater in Group A. Conclusions: GTR technique has advantages over subepithelial connective tissue graft for shallow Miller’s Class I defects and this procedure can be used to avoid patient discomfort and reduce treatment time. Key words:Collagen membrane, comparative split mouth study, gingival recession, subepithelial connective tissue graft, guided tissue regeneration (GTR). PMID:25136420

Section of Morgan formation, Pennsylvanian, at Split Mountain in Dinosaur National Monument, Uintah County, Utah

USGS Publications Warehouse

McCann, Franklin T.; Raman, Norman D.; Henbest, Lloyd G.

1946-01-01

Extension of the oil pool in the Weber sandstone (Pennsylvanian), in the Rangely oil field, Rio Blanco County, Colorado, subsequent to the completion of the filed work on which Preliminary Chart 16 is based, has stimulated special interest in the beds beneath that sandstone as potential oil reservoirs. In compliance with the demand for additional information concerning these beds, a detailed description of the sequence immediately underlying the Weber sandstone at Split Mountain, Utah, is here given. That part of Split Mountain where the section was measured is approximately 35 airline miles northwest of the town of Rangely. The section itself is shown graphically and somewhat generalized in column 8, sheet 2, Preliminary Chart 16. A more detailed graphic section is presented in the accompanying column section.

A STRICTLY CONTRACTIVE PEACEMAN–RACHFORD SPLITTING METHOD FOR CONVEX PROGRAMMING

PubMed Central

BINGSHENG, HE; LIU, HAN; WANG, ZHAORAN; YUAN, XIAOMING

2014-01-01

In this paper, we focus on the application of the Peaceman–Rachford splitting method (PRSM) to a convex minimization model with linear constraints and a separable objective function. Compared to the Douglas–Rachford splitting method (DRSM), another splitting method from which the alternating direction method of multipliers originates, PRSM requires more restrictive assumptions to ensure its convergence, while it is always faster whenever it is convergent. We first illustrate that the reason for this difference is that the iterative sequence generated by DRSM is strictly contractive, while that generated by PRSM is only contractive with respect to the solution set of the model. With only the convexity assumption on the objective function of the model under consideration, the convergence of PRSM is not guaranteed. But for this case, we show that the first t iterations of PRSM still enable us to find an approximate solution with an accuracy of O(1/t). A worst-case O(1/t) convergence rate of PRSM in the ergodic sense is thus established under mild assumptions. After that, we suggest attaching an underdetermined relaxation factor with PRSM to guarantee the strict contraction of its iterative sequence and thus propose a strictly contractive PRSM. A worst-case O(1/t) convergence rate of this strictly contractive PRSM in a nonergodic sense is established. We show the numerical efficiency of the strictly contractive PRSM by some applications in statistical learning and image processing. PMID:25620862

ANALYSIS OF THE WATER-SPLITTING CAPABILITIES OF GALLIUM INDIUM PHOSPHIDE NITRIDE (GaInPN)

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

Head, J.; Turner, J.

2007-01-01

With increasing demand for oil, the fossil fuels used to power society’s vehicles and homes are becoming harder to obtain, creating pollution problems and posing hazard’s to people’s health. Hydrogen, a clean and effi cient energy carrier, is one alternative to fossil fuels. Certain semiconductors are able to harness the energy of solar photons and direct it into water electrolysis in a process known as photoelectrochemical water-splitting. P-type gallium indium phosphide (p-GaInP2) in tandem with GaAs is a semiconductor system that exhibits water-splitting capabilities with a solar-tohydrogen effi ciency of 12.4%. Although this material is effi cient at producing hydrogenmore » through photoelectrolysis it has been shown to be unstable in solution. By introducing nitrogen into this material, there is great potential for enhanced stability. In this study, gallium indium phosphide nitride Ga1-yInyP1-xNx samples were grown using metal-organic chemical vapor deposition in an atmospheric-pressure vertical reactor. Photocurrent spectroscopy determined these materials to have a direct band gap around 2.0eV. Mott-Schottky analysis indicated p-type behavior with variation in fl atband potentials with varied frequencies and pH’s of solutions. Photocurrent onset and illuminated open circuit potential measurements correlated to fl atband potentials determined from previous studies. Durability analysis suggested improved stability over the GaInP2 system.« less

Magnetic field drift shell splitting - Cause of unusual dayside particle pitch angle distributions during storms and substorms

NASA Technical Reports Server (NTRS)

Sibeck, D. G.; Mcentire, R. W.; Lui, A. T. Y.; Lopez, R. E.; Krimigis, S. M.

1987-01-01

This paper presents a magnetic field drift shell-splitting model for the unusual butterfly and head-and-shoulder energetic (E greater than 25 keV) particle pitch angle distributions (PADs) which appear deep within the dayside magnetosphere during the course of storms and substorms. Drift shell splitting separates the high and low pitch angle particles in nightside injections as they move to the dayside magnetosphere, so that the higher pitch angle particles move radially away from earth. Consequently, butterfly PADs with a surplus of low pitch angle particles form on the inner edge of the injection, but head-and-shoulder PADs with a surplus of high pitch angle particles form on the outer edge. A similar process removes high pitch angle particles from the inner dayside magnetosphere during storms, leaving the remaining lower pitch angle particles to form butterfly PADs on the inner edge of the ring current. A detailed case and statistical study of Charge Composition Explorer/Medium-energy Particle Analyzer observations, as well as a review of previous work, shows most examples of unusual PADs to be consistent with the model.

Split-face histological and biochemical evaluation of tightening efficacy using temperature- and impedance-controlled continuous non-invasive radiofrequency energy.

PubMed

Boisnic, Sylvie; Divaris, Marc; Branchet, Marie-Christine; Nelson, Andrew A

2017-06-01

Bipolar radiofrequency (RF) is capable of heating dermal collagen fibers and inducing skin tightening by collagen remodeling. To substantiate safety and improvement of skin laxity following skin heating with a novel temperature- and impedance-controlled non-invasive radiofrequency (RF) device by histological and biochemical evaluations. A split-face study was performed on 4 subjects who underwent 8 weekly RF sessions on one side of their face, leaving the other side an untreated control and then underwent facelift procedure. Clinical evaluation by photographs was done prior to the surgical procedure. Ex vivo fragments were harvested from both sides and compared. Morphometric analysis of dermal collagen fibers, collagen synthesis, and elastin synthesis evaluations were compared in triplicates. Facial skin tightening was apparent in split-face photographs. A significant increase of 7.9% in dermal collagen content, and a significant increase of 34.7% in collagen synthesis were demonstrated in the treated samples. No statistically significant effect on elastin synthesis was detected. Skin tightening following treatment with non-invasive RF has proven histologically and biochemically to derive from increase in dermal collagen synthesis and content.

Comparing nonparametric Bayesian tree priors for clonal reconstruction of tumors.

PubMed

Deshwar, Amit G; Vembu, Shankar; Morris, Quaid

2015-01-01

Statistical machine learning methods, especially nonparametric Bayesian methods, have become increasingly popular to infer clonal population structure of tumors. Here we describe the treeCRP, an extension of the Chinese restaurant process (CRP), a popular construction used in nonparametric mixture models, to infer the phylogeny and genotype of major subclonal lineages represented in the population of cancer cells. We also propose new split-merge updates tailored to the subclonal reconstruction problem that improve the mixing time of Markov chains. In comparisons with the tree-structured stick breaking prior used in PhyloSub, we demonstrate superior mixing and running time using the treeCRP with our new split-merge procedures. We also show that given the same number of samples, TSSB and treeCRP have similar ability to recover the subclonal structure of a tumor…

SKS Splitting and the Scale of Vertical Coherence of the Taiwan Mountain Belt

NASA Astrophysics Data System (ADS)

Kuo, Ban-Yuan; Lin, Shu-Chuan; Lin, Yi-Wei

2018-02-01

Many continental orogens feature a pattern of SKS shear wave splitting with fast polarization directions parallel to the mountain fabrics and delay times of 1-2 s, implying that the crust and lithosphere deform consistently. In the Taiwan arc-continent collision zone, similar pattern of SKS splitting exists, and thereby lithospheric scale deformation due to collision has been assumed. However, recent dynamic modeling demonstrated that the SKS splitting in Taiwan can be generated by the toroidal flow in the asthenosphere induced by the subduction of the Philippine Sea plate and the Eurasian plate. To further evaluate this hypothesis, we analyzed a new data set using a quantitative approach. The results show that models with slab geometries constrained by seismicity explain the observed fast splitting direction to within 25°, whereas the misfit grows to 50-60° if the toroidal flow is disrupted by the presence of a sizable aseismic slab beneath central Taiwan as often suggested by tomographic imaging. However, small sized aseismic slab or detached slab fragment can potentially reconcile the splitting observations. We estimated the scale of vertical coherence to be 10-40 km in the lithosphere and 100-150 km in the asthenosphere, making the former unfavorable for accumulating large delay times. The low coherence is caused by the subduction of the Eurasian plate that creates complex deformation different from what characterizes the compressional tectonics above the plate. This suggests that the mountain building in Taiwan is a shallow process, rather than lithospheric in scale.

Tunable electronic structure and spin splitting in single and multiple Fe-adsorbed g-C2N with different layers: A first-principles study

NASA Astrophysics Data System (ADS)

Zheng, Z. D.; Wang, X. C.; Mi, W. B.

2018-04-01

The electronic structure of Fe adsorbed g-C2N with different layers is investigated by first-principles calculations. The Fe1 and Fe2 represent the Fe adsorptions at Csbnd C and Csbnd N rings, and Fe11 and Fe121 adsorption sites are also considered. The Fe1 adsorbed g-C2N is metallic with layer from n = 1 to 4, and the maximum spin splitting is 515, 428, 46 and 133 meV. The band gap of Fe2 adsorbed g-C2N with different layers is 0, 0, 117 and 6 meV, and the maximum spin splitting is 565, 369, 195 and 146 meV, respectively. All of the Fe11 adsorbed g-C2N are metallic with layer from n = 1 to 4, and the maximum spin splitting is 199, 0, 83 and 203 meV. An indirect band gap of 215 meV appears in Fe121 adsorbed g-C2N at layer n = 3, and the maximum spin splitting is 283, 211, 304 and 153 meV, respectively. Our results show that the electronic structures of Fe adsorbed novel two-dimensional semiconductor g-C2N can be tuned by different layers. Moreover, the spin splitting of Fe2 adsorbed g-C2N decreases monotonically as g-C2N layer increases from n = 1 to 4, which will provide more potential applications in spintronic devices.

Computational Screening of 2D Materials for Photocatalysis.

PubMed

Singh, Arunima K; Mathew, Kiran; Zhuang, Houlong L; Hennig, Richard G

2015-03-19

Two-dimensional (2D) materials exhibit a range of extraordinary electronic, optical, and mechanical properties different from their bulk counterparts with potential applications for 2D materials emerging in energy storage and conversion technologies. In this Perspective, we summarize the recent developments in the field of solar water splitting using 2D materials and review a computational screening approach to rapidly and efficiently discover more 2D materials that possess properties suitable for solar water splitting. Computational tools based on density-functional theory can predict the intrinsic properties of potential photocatalyst such as their electronic properties, optical absorbance, and solubility in aqueous solutions. Computational tools enable the exploration of possible routes to enhance the photocatalytic activity of 2D materials by use of mechanical strain, bias potential, doping, and pH. We discuss future research directions and needed method developments for the computational design and optimization of 2D materials for photocatalysis.

Complete characterization of the water dimer vibrational ground state and testing the VRT(ASP-W)III, SAPT-5st, and VRT(MCY-5f) surfaces

NASA Astrophysics Data System (ADS)

Keutsch, Frank N.; Goldman, Nir; Harker, Heather A.; Leforestier, Claude; Saykally, Richard J.

We report the observation of extensive a- and c-type rotation-tunnelling (RT) spectra of (H2O)2 for Ka =0-3, and (D2O)2 for Ka =0-4. These data allow a detailed characterization of the vibrational ground state to energies comparable to those of the low-lying (70-80 cm-1) intermolecular vibrations. We present a comparison of the experimentally determined molecular constants and tunnelling splittings with those calculated on the VRT(ASP-W)III, SAPT-5st, and VRT(MCY-5f) intermolecular potential energy surfaces. The SAPT-5st potential reproduces the vibrational ground state properties of the water dimer very well. The VRT(MCY-5f) and especially the VRT(ASP-W)III potentials show larger disagreements, in particular for the bifurcation tunnelling splitting.

Nuclear symmetry energy in terms of single-nucleon potential and its effect on the proton fraction of β-stable npeμ matter

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

Sahoo, Babita, E-mail: patra-babita@rediffmail.com; Chakraborty, Suparna, E-mail: banerjee.suparna@hotmail.com; Sahoo, Sukadev, E-mail: sukadevsahoo@yahoo.com

2016-01-15

Momentum and density dependence of single-nucleon potential u{sub τ} (k, ρ, β) is analyzed using a density dependent finite range effective interaction of the Yukawa form. Depending on the choice of the strength parameters of exchange interaction, two different trends of the momentum dependence of nuclear symmetry potential are noticed which lead to two opposite types of neutron and proton effective mass splitting. The 2nd-order and 4th-order symmetry energy of isospin asymmetric nuclear matter are expressed analytically in terms of the single-nucleon potential. Two distinct behavior of the density dependence of 2nd-order and 4th-order symmetry energy are observed depending onmore » neutron and proton effective mass splitting. It is also found that the 4th-order symmetry energy has a significant contribution towards the proton fraction of β-stable npeμ matter at high densities.« less

Tantalum-based semiconductors for solar water splitting.

PubMed

Zhang, Peng; Zhang, Jijie; Gong, Jinlong

2014-07-07

Solar energy utilization is one of the most promising solutions for the energy crises. Among all the possible means to make use of solar energy, solar water splitting is remarkable since it can accomplish the conversion of solar energy into chemical energy. The produced hydrogen is clean and sustainable which could be used in various areas. For the past decades, numerous efforts have been put into this research area with many important achievements. Improving the overall efficiency and stability of semiconductor photocatalysts are the research focuses for the solar water splitting. Tantalum-based semiconductors, including tantalum oxide, tantalate and tantalum (oxy)nitride, are among the most important photocatalysts. Tantalum oxide has the band gap energy that is suitable for the overall solar water splitting. The more negative conduction band minimum of tantalum oxide provides photogenerated electrons with higher potential for the hydrogen generation reaction. Tantalates, with tunable compositions, show high activities owning to their layered perovskite structure. (Oxy)nitrides, especially TaON and Ta3N5, have small band gaps to respond to visible-light, whereas they can still realize overall solar water splitting with the proper positions of conduction band minimum and valence band maximum. This review describes recent progress regarding the improvement of photocatalytic activities of tantalum-based semiconductors. Basic concepts and principles of solar water splitting will be discussed in the introduction section, followed by the three main categories regarding to the different types of tantalum-based semiconductors. In each category, synthetic methodologies, influencing factors on the photocatalytic activities, strategies to enhance the efficiencies of photocatalysts and morphology control of tantalum-based materials will be discussed in detail. Future directions to further explore the research area of tantalum-based semiconductors for solar water splitting are also discussed.

Crystal-field splittings in rare-earth-based hard magnets: An ab initio approach

NASA Astrophysics Data System (ADS)

Delange, Pascal; Biermann, Silke; Miyake, Takashi; Pourovskii, Leonid

2017-10-01

We apply the first-principles density functional theory + dynamical mean-field theory framework to evaluate the crystal-field splitting on rare-earth sites in hard magnetic intermetallics. An atomic (Hubbard-I) approximation is employed for local correlations on the rare-earth 4 f shell and self-consistency in the charge density is implemented. We reduce the density functional theory self-interaction contribution to the crystal-field splitting by properly averaging the 4 f charge density before recalculating the one-electron Kohn-Sham potential. Our approach is shown to reproduce the experimental crystal-field splitting in the prototypical rare-earth hard magnet SmCo5. Applying it to R Fe12 and R Fe12X hard magnets (R =Nd , Sm and X =N , Li), we obtain in particular a large positive value of the crystal-field parameter A20〈r2〉 in NdFe12N resulting in a strong out-of-plane anisotropy observed experimentally. The sign of A20〈r2〉 is predicted to be reversed by substituting N with Li, leading to a strong out-of-plane anisotropy in SmFe12Li . We discuss the origin of this strong impact of N and Li interstitials on the crystal-field splitting on rare-earth sites.

Efficient solar-to-fuels production from a hybrid microbial–water-splitting catalyst system

PubMed Central

Torella, Joseph P.; Gagliardi, Christopher J.; Chen, Janice S.; Bediako, D. Kwabena; Colón, Brendan; Way, Jeffery C.; Silver, Pamela A.; Nocera, Daniel G.

2015-01-01

Photovoltaic cells have considerable potential to satisfy future renewable-energy needs, but efficient and scalable methods of storing the intermittent electricity they produce are required for the large-scale implementation of solar energy. Current solar-to-fuels storage cycles based on water splitting produce hydrogen and oxygen, which are attractive fuels in principle but confront practical limitations from the current energy infrastructure that is based on liquid fuels. In this work, we report the development of a scalable, integrated bioelectrochemical system in which the bacterium Ralstonia eutropha is used to efficiently convert CO2, along with H2 and O2 produced from water splitting, into biomass and fusel alcohols. Water-splitting catalysis was performed using catalysts that are made of earth-abundant metals and enable low overpotential water splitting. In this integrated setup, equivalent solar-to-biomass yields of up to 3.2% of the thermodynamic maximum exceed that of most terrestrial plants. Moreover, engineering of R. eutropha enabled production of the fusel alcohol isopropanol at up to 216 mg/L, the highest bioelectrochemical fuel yield yet reported by >300%. This work demonstrates that catalysts of biotic and abiotic origin can be interfaced to achieve challenging chemical energy-to-fuels transformations. PMID:25675518

Intraband magneto-optical absorption in InAs/GaAs quantum dots: Orbital Zeeman splitting and the Thomas-Reiche-Kuhn sum rule

NASA Astrophysics Data System (ADS)

Zhang, J.-Z.; Galbraith, I.

2008-05-01

Using perturbation theory, intraband magneto-optical absorption is calculated for InAs/GaAs truncated pyramidal quantum dots in a magnetic field applied parallel to the growth direction z . The effects of the magnetic field on the electronic states as well as the intraband transitions are systematically studied. Selection rules governing the intraband transitions are discussed based on the symmetry properties of the electronic states. While the broadband z -polarized absorption is almost insensitive to the magnetic field, the orbital Zeeman splitting is the dominant feature in the in-plane polarized spectrum. Strong in-plane polarized magneto-absorption features are located in the far-infrared region, while z -polarized absorption occurs at higher frequencies. This is due to the dot geometry (the base length is much larger than the height) yielding different quantum confinement in the vertical and lateral directions. The Thomas-Reiche-Kuhn sum rule, including the magnetic field effect, is applied together with the selection rules to the absorption spectra. The orbital Zeeman splitting depends on both the dot size and the confining potential—the splitting decreases as the dot size or the confining potential decreases. Our calculated Zeeman splittings are in agreement with experimental data.

Water splitting on semiconductor catalysts under visible-light irradiation.

PubMed

Navarro Yerga, Rufino M; Alvarez Galván, M Consuelo; del Valle, F; Villoria de la Mano, José A; Fierro, José L G

2009-01-01

Sustainable hydrogen production is a key target for the development of alternative, future energy systems that will provide a clean and affordable energy supply. The Sun is a source of silent and precious energy that is distributed fairly all over the Earth daily. However, its tremendous potential as a clean, safe, and economical energy source cannot be exploited unless the energy is accumulated or converted into more useful forms. The conversion of solar energy into hydrogen via the water-splitting process, assisted by photo-semiconductor catalysts, is one of the most promising technologies for the future because large quantities of hydrogen can potentially be generated in a clean and sustainable manner. This Minireview provides an overview of the principles, approaches, and research progress on solar hydrogen production via the water-splitting reaction on photo-semiconductor catalysts. It presents a survey of the advances made over the last decades in the development of catalysts for photochemical water splitting under visible-light irradiation. The Minireview also analyzes the energy requirements and main factors that determine the activity of photocatalysts in the conversion of water into hydrogen and oxygen using sunlight. Remarkable progress has been made since the pioneering work by Fujishima and Honda in 1972, but he development of photocatalysts with improved efficiencies for hydrogen production from water using solar energy still faces major challenges. Research strategies and approaches adopted in the search for active and efficient photocatalysts, for example through new materials and synthesis methods, are presented and analyzed.

Fierz bilinear formulation of the Maxwell-Dirac equations and symmetry reductions

NASA Astrophysics Data System (ADS)

Inglis, Shaun; Jarvis, Peter

2014-09-01

We study the Maxwell-Dirac equations in a manifestly gauge invariant presentation using only the spinor bilinear scalar and pseudoscalar densities, and the vector and pseudovector currents, together with their quadratic Fierz relations. The internally produced vector potential is expressed via algebraic manipulation of the Dirac equation, as a rational function of the Fierz bilinears and first derivatives (valid on the support of the scalar density), which allows a gauge invariant vector potential to be defined. This leads to a Fierz bilinear formulation of the Maxwell tensor and of the Maxwell-Dirac equations, without any reference to gauge dependent quantities. We show how demanding invariance of tensor fields under the action of a fixed (but arbitrary) Lie subgroup of the Poincaré group leads to symmetry reduced equations. The procedure is illustrated, and the reduced equations worked out explicitly for standard spherical and cylindrical cases, which are coupled third order nonlinear PDEs. Spherical symmetry necessitates the existence of magnetic monopoles, which do not affect the coupled Maxwell-Dirac system due to magnetic terms cancelling. In this paper we do not take up numerical computations. As a demonstration of the power of our approach, we also work out the symmetry reduced equations for two distinct classes of dimension 4 one-parameter families of Poincaré subgroups, one splitting and one non-splitting. The splitting class yields no solutions, whereas for the non-splitting class we find a family of formal exact solutions in closed form.

Statistical physics and economic fluctuations: do outliers exist?

NASA Astrophysics Data System (ADS)

Stanley, H. Eugene

2003-02-01

We present an overview of recent research applying ideas of statistical physics to try to better understand puzzles regarding economic fluctuations. One of these puzzles is how to describe outliers, phenomena that lie outside of patterns of statistical regularity. We review evidence consistent with the possibility that such outliers may not exist. This possibility is supported by recent analysis by Plerou et al. of a database containing the bid, ask, and sale price of each trade of every stock. Further, the data support the picture of economic fluctuations, due to Plerou et al., in which a financial market alternates between being in an “equilibrium phase” where market behavior is split roughly equally between buying and selling, and an “out-of-equilibrium phase” where the market is mainly either buying or selling.

Objective research of auscultation signals in Traditional Chinese Medicine based on wavelet packet energy and support vector machine.

PubMed

Yan, Jianjun; Shen, Xiaojing; Wang, Yiqin; Li, Fufeng; Xia, Chunming; Guo, Rui; Chen, Chunfeng; Shen, Qingwei

2010-01-01

This study aims at utilising Wavelet Packet Transform (WPT) and Support Vector Machine (SVM) algorithm to make objective analysis and quantitative research for the auscultation in Traditional Chinese Medicine (TCM) diagnosis. First, Wavelet Packet Decomposition (WPD) at level 6 was employed to split more elaborate frequency bands of the auscultation signals. Then statistic analysis was made based on the extracted Wavelet Packet Energy (WPE) features from WPD coefficients. Furthermore, the pattern recognition was used to distinguish mixed subjects' statistical feature values of sample groups through SVM. Finally, the experimental results showed that the classification accuracies were at a high level.

Porcelain surface conditioning protocols and shear bond strength of orthodontic brackets.

PubMed

Lestrade, Ashley M; Ballard, Richard W; Xu, Xiaoming; Yu, Qingzhao; Kee, Edwin L; Armbruster, Paul C

2016-05-01

The objective of the present study was to determine which of six bonding protocols yielded a clinically acceptable shear bond strength (SBS) of metal orthodontic brackets to CAD/CAM lithium disilicate porcelain restorations. A secondary aim was to determine which bonding protocol produced the least surface damage at debond. Sixty lithium disilicate samples were fabricated to replicate the facial surface of a mandibular first molar using a CEREC CAD/CAM machine. The samples were split into six test groups, each of which received different mechanical/chemical pretreatment protocols to roughen the porcelain surface prior to bonding a molar orthodontic attachment. Shear bond strength testing was conducted using an Instron machine. The mean, maximum, minimal, and standard deviation SBS values for each sample group including an enamel control were calculated. A t-test was used to evaluate the statistical significance between the groups. No significant differences were found in SBS values, with the exception of surface roughening with a green stone prior to HFA and silane treatment. This protocol yielded slightly higher bond strength which was statistically significant. Chemical treatment alone with HFA/silane yielded SBS values within an acceptable clinical range to withstand forces applied by orthodontic treatment and potentially eliminates the need to mechanically roughen the ceramic surface.

Upper Mantle Dynamics of Bangladesh by Splitting Analyzes of Core Refracted SKS and SKKS Waves

NASA Astrophysics Data System (ADS)

Tiwari, A. K.; Bhushan, K.; Eken, T.; Singh, A.

2017-12-01

New shear wave splitting measurements are obtained from hitherto less studied Bengal Basin using core refracted SKS and SKKS phases. Splitting parameters, time delays (δt) and fast polarization directions (Φ) were estimated through analysis of 64 high-quality waveforms (≥ 2.5 signal to noise ratio) from 29 earthquakes with magnitude ≥5.5 recorded at eight seismic stations deployed over Bangladesh. We found no evidence of splitting which indicates azimuthal isotropy beneath the region. Null measurements can be explained by near vertical axis of anisotropy or by the presence of multiple anisotropic layers with different fast polarization directions, where combined effect results in null. We consider that the presence of partial melts within the upper mantle due to Kerguelen mantle plume activities may be the potential geodynamic cause for observed null measurements. It locally perturbed mantle convection flow beneath the region and reoriented the lattice preferred orientation of the upper mantle mineral mainly olivine as this disabled the core refracted SKS and SKKS phases to scan the anisotropic characteristics of the region, and hence null measurements are obtained.

Dynamic splitting of Gaussian pencil beams in heterogeneity-correction algorithms for radiotherapy with heavy charged particles.

PubMed

Kanematsu, Nobuyuki; Komori, Masataka; Yonai, Shunsuke; Ishizaki, Azusa

2009-04-07

The pencil-beam algorithm is valid only when elementary Gaussian beams are small enough compared to the lateral heterogeneity of a medium, which is not always true in actual radiotherapy with protons and ions. This work addresses a solution for the problem. We found approximate self-similarity of Gaussian distributions, with which Gaussian beams can split into narrower and deflecting daughter beams when their sizes have overreached lateral heterogeneity in the beam-transport calculation. The effectiveness was assessed in a carbon-ion beam experiment in the presence of steep range compensation, where the splitting calculation reproduced a detour effect amounting to about 10% in dose or as large as the lateral particle disequilibrium effect. The efficiency was analyzed in calculations for carbon-ion and proton radiations with a heterogeneous phantom model, where the beam splitting increased computing times by factors of 4.7 and 3.2. The present method generally improves the accuracy of the pencil-beam algorithm without severe inefficiency. It will therefore be useful for treatment planning and potentially other demanding applications.

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

Zhai, Yaxin; Baniya, Sangita; Zhang, Chuang

Two-dimensional (2D) layered hybrid organic-inorganic halide perovskite semiconductors form natural “multiple quantum wells” that have strong spin-orbit coupling due to the heavy elements in their building blocks. This may lead to “Rashba splitting” close to the extrema in the electron bands. We have used a plethora of ultrafast transient, nonlinear optical spectroscopies and theoretical calculations to study the primary (excitons) and long-lived (free carriers) photoexcitations in thin films of 2D perovskite, namely, (C 6H 5C 2H 4NH 3) 2PbI 4. The density functional theory calculation shows the occurrence of Rashba splitting in the plane perpendicular to the 2D barrier. Frommore » the electroabsorption spectrum and photoinduced absorption spectra from excitons and free carriers, we obtain a giant Rashba splitting in this compound, with energy splitting of (40 ± 5) meV and Rashba parameter of (1.6 ± 0.1) eV·Å, which are among the highest Rashba splitting size parameters reported so far. In conclusion, this finding shows that 2D hybrid perovskites have great promise for potential applications in spintronics.« less

Covalent Surface Modification of Gallium Arsenide Photocathodes for Water Splitting in Highly Acidic Electrolyte.

PubMed

Garner, Logan E; Steirer, K Xerxes; Young, James L; Anderson, Nicholas C; Miller, Elisa M; Tinkham, Jonathan S; Deutsch, Todd G; Sellinger, Alan; Turner, John A; Neale, Nathan R

2017-02-22

Efficient water splitting using light as the only energy input requires stable semiconductor electrodes with favorable energetics for the water-oxidation and proton-reduction reactions. Strategies to tune electrode potentials using molecular dipoles adsorbed to the semiconductor surface have been pursued for decades but are often based on weak interactions and quickly react to desorb the molecule under conditions relevant to sustained photoelectrolysis. Here, we show that covalent attachment of fluorinated, aromatic molecules to p-GaAs(1 0 0) surfaces can be employed to tune the photocurrent onset potentials of p-GaAs(1 0 0) photocathodes and reduce the external energy required for water splitting. Results indicate that initial photocurrent onset potentials can be shifted by nearly 150 mV in pH -0.5 electrolyte under 1 Sun (1000 W m -2 ) illumination resulting from the covalently bound surface dipole. Though X-ray photoelectron spectroscopy analysis reveals that the covalent molecular dipole attachment is not robust under extended 50 h photoelectrolysis, the modified surface delays arsenic oxide formation that results in a p-GaAs(1 0 0) photoelectrode operating at a sustained photocurrent density of -20.5 mA cm -2 within -0.5 V of the reversible hydrogen electrode. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved Stability and Performance of Visible Photoelectrochemical Water Splitting on Solution-Processed Organic Semiconductor Thin Films by Ultrathin Metal Oxide Passivation

DOE PAGES

Wang, Lei; Yan, Danhua; Shaffer, David W.; ...

2017-12-27

Solution-processable organic semiconductors have potentials as visible photoelectrochemical (PEC) water splitting photoelectrodes due to their tunable small band gap and electronic energy levels, but they are typically limited by poor stability and photocatalytic activity. In this study, we demonstrate the direct visible PEC water oxidation on solution-processed organic semiconductor thin films with improved stability and performance by ultrathin metal oxide passivation layers. N-type fullerene-derivative thin films passivated by sub-2 nm ZnO via atomic layer deposition enabled the visible PEC water oxidation at wavelengths longer than 600 nm in harsh alkaline electrolyte environments with up to 30 μA/cm 2 photocurrents atmore » the thermodynamic water-oxidation equilibrium potential and the photoanode half-lifetime extended to ~1000 s. The systematic investigation reveals the enhanced water oxidation catalytic activity afforded by ZnO passivation and the charge tunneling governing the hole transfer through passivation layers. Further enhanced PEC performances were realized by improving the bottom ohmic contact to the organic semiconductor, achieving ~60 μA/cm 2 water oxidation photocurrent at the equilibrium potential, the highest values reported for organic semiconductor thin films to our knowledge. The improved stability and performance of passivated organic photoelectrodes and discovered design rationales provide useful guidelines for realizing the stable visible solar PEC water splitting based on organic semiconductor thin films.« less

Improved Stability and Performance of Visible Photoelectrochemical Water Splitting on Solution-Processed Organic Semiconductor Thin Films by Ultrathin Metal Oxide Passivation

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

Wang, Lei; Yan, Danhua; Shaffer, David W.

Solution-processable organic semiconductors have potentials as visible photoelectrochemical (PEC) water splitting photoelectrodes due to their tunable small band gap and electronic energy levels, but they are typically limited by poor stability and photocatalytic activity. In this study, we demonstrate the direct visible PEC water oxidation on solution-processed organic semiconductor thin films with improved stability and performance by ultrathin metal oxide passivation layers. N-type fullerene-derivative thin films passivated by sub-2 nm ZnO via atomic layer deposition enabled the visible PEC water oxidation at wavelengths longer than 600 nm in harsh alkaline electrolyte environments with up to 30 μA/cm 2 photocurrents atmore » the thermodynamic water-oxidation equilibrium potential and the photoanode half-lifetime extended to ~1000 s. The systematic investigation reveals the enhanced water oxidation catalytic activity afforded by ZnO passivation and the charge tunneling governing the hole transfer through passivation layers. Further enhanced PEC performances were realized by improving the bottom ohmic contact to the organic semiconductor, achieving ~60 μA/cm 2 water oxidation photocurrent at the equilibrium potential, the highest values reported for organic semiconductor thin films to our knowledge. The improved stability and performance of passivated organic photoelectrodes and discovered design rationales provide useful guidelines for realizing the stable visible solar PEC water splitting based on organic semiconductor thin films.« less

Copper Oxide Nanograss for Efficient and Stable Photoelectrochemical Hydrogen Production by Water Splitting

NASA Astrophysics Data System (ADS)

Borkar, Rajnikant; Dahake, Rashmi; Rayalu, Sadhana; Bansiwal, Amit

2018-03-01

A biphasic copper oxide thin film of grass-like appendage morphology is synthesized by two-step electro-deposition method and later investigated for photoelectrochemical (PEC) water splitting for hydrogen production. Further, the thin film was characterized by UV-Visible spectroscopy, x-ray diffraction (XRD), Scanning electron microscopy (SEM) and PEC techniques. The XRD analysis confirms formation of biphasic copper oxide phases, and SEM reveals high surface area grass appendage-like morphology. These grass appendage structures exhibit a high cathodic photocurrent of - 1.44 mAcm-2 at an applied bias of - 0.7 (versus Ag/AgCl) resulting in incident to photon current efficiency (IPCE) of ˜ 10% at 400 nm. The improved light harvesting and charge transport properties of grass appendage structured biphasic copper oxides makes it a potential candidate for PEC water splitting for hydrogen production.

Anatomy of exotic Higgs decays in 2HDM

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

Kling, Felix; No, Jose Miguel; Su, Shufang

Large mass splittings between new scalars in two-Higgs-doublet models (2HDM) open a key avenue to search for these new states via exotic heavy Higgs decays. We discuss in detail the different search channels for these new scalars at the LHC in the presence of a sizable mass splitting, i.e. a hierarchical 2HDM scenario, taking into account the theoretical and experimental constraints. Here, we provide benchmark planes to exploit the complementarity among these searches, analyzing their potential to probe the hierarchical 2HDM parameter space during LHC Run 2.

Anatomy of exotic Higgs decays in 2HDM

NASA Astrophysics Data System (ADS)

Kling, Felix; No, Jose Miguel; Su, Shufang

2016-09-01

Large mass splittings between new scalars in two-Higgs-doublet models (2HDM) open a key avenue to search for these new states via exotic heavy Higgs decays. We discuss in detail the different search channels for these new scalars at the LHC in the presence of a sizable mass splitting, i.e. a hierarchical 2HDM scenario, taking into account the theoretical and experimental constraints. We provide benchmark planes to exploit the complementarity among these searches, analyzing their potential to probe the hierarchical 2HDM parameter space during LHC Run 2.

Application of the Monte Carlo method for building up models for octanol-water partition coefficient of platinum complexes

NASA Astrophysics Data System (ADS)

Toropov, Andrey A.; Toropova, Alla P.

2018-06-01

Predictive model of logP for Pt(II) and Pt(IV) complexes built up with the Monte Carlo method using the CORAL software has been validated with six different splits into the training and validation sets. The improving of the predictive potential of models for six different splits has been obtained using so-called index of ideality of correlation. The suggested models give possibility to extract molecular features, which cause the increase or vice versa decrease of the logP.

Anatomy of exotic Higgs decays in 2HDM

DOE PAGES

Kling, Felix; No, Jose Miguel; Su, Shufang

2016-09-16

Large mass splittings between new scalars in two-Higgs-doublet models (2HDM) open a key avenue to search for these new states via exotic heavy Higgs decays. We discuss in detail the different search channels for these new scalars at the LHC in the presence of a sizable mass splitting, i.e. a hierarchical 2HDM scenario, taking into account the theoretical and experimental constraints. Here, we provide benchmark planes to exploit the complementarity among these searches, analyzing their potential to probe the hierarchical 2HDM parameter space during LHC Run 2.

The development of algorithms for the deployment of new version of GEM-detector-based acquisition system

NASA Astrophysics Data System (ADS)

Krawczyk, Rafał D.; Czarski, Tomasz; Kolasiński, Piotr; Linczuk, Paweł; Poźniak, Krzysztof T.; Chernyshova, Maryna; Kasprowicz, Grzegorz; Wojeński, Andrzej; Zabolotny, Wojciech; Zienkiewicz, Paweł

2016-09-01

This article is an overview of what has been implemented in the process of development and testing the GEM detector based acquisition system in terms of post-processing algorithms. Information is given on mex functions for extended statistics collection, unified hex topology and optimized S-DAQ algorithm for splitting overlapped signals. Additional discussion on bottlenecks and major factors concerning optimization is presented.

Instant dentin hypersensitivity relief of a single topical application of an in-office desensitizing paste containing 8% arginine and calcium carbonate: a split-mouth, randomized-controlled study.

PubMed

Kapferer, Ines; Pflug, Claudia; Kisielewsky, Irene; Giesinger, Johannes; Beier, Ulrike S; Dumfahrt, Herbert

2013-01-01

The aim of this study was to evaluate the clinical efficacy of an in-office desensitizing paste containing 8% arginine and calcium carbonate relative to calcium carbonate alone in the reduction of dentin hypersensitivity in a randomized, double-blind, split-mouth clinical trial. Sixty teeth (30 subjects) with an air blast hypersensitivity score of 2 or 3 (Schiff Cold Air Sensitivity Scale) were randomly assigned to one of two treatment groups: (1) test paste containing 8% arginine and calcium carbonate (elmex sensitive professional desensitizing paste) and (2) control paste: paris white (calcium carbonate). Tactile and air blast dentin hypersensitivity examinations were performed at baseline, immediately after paste application and 4 and 12 weeks later. A statistically significant difference in air blast (p = 0.001) and tactile (p = 0.047) hypersensitivity reduction over time was observed between the two therapy modes. After 12-weeks, statistically significant differences were indicated between the test and control group with respect to baseline-adjusted mean tactile (41.94%; p = 0.038) and air blast hypersensitivity scores (46.5%; p = 0.017). The tested in-office desensitizing paste containing 8.0% arginine and calcium carbonate provides significantly greater hypersensitivity relief compared to calcium carbonate alone.

Observation of Spin Hall Effect in Photon Tunneling via Weak Measurements

PubMed Central

Zhou, Xinxing; Ling, Xiaohui; Zhang, Zhiyou; Luo, Hailu; Wen, Shuangchun

2014-01-01

Photonic spin Hall effect (SHE) manifesting itself as spin-dependent splitting escapes detection in previous photon tunneling experiments due to the fact that the induced beam centroid shift is restricted to a fraction of wavelength. In this work, we report on the first observation of this tiny effect in photon tunneling via weak measurements based on preselection and postselection technique on the spin states. We find that the spin-dependent splitting is even larger than the potential barrier thickness when spin-polarized photons tunneling through a potential barrier. This photonic SHE is attributed to spin-redirection Berry phase which can be described as a consequence of the spin-orbit coupling. These findings provide new insight into photon tunneling effect and thereby offer the possibility of developing spin-based nanophotonic applications. PMID:25487043

Visible-light absorption and large band-gap bowing of GaN 1-xSb x from first principles

DOE PAGES

Sheetz, R. Michael; Richter, Ernst; Andriotis, Antonis N.; ...

2011-08-01

Applicability of the Ga(Sb x)N 1-x alloys for practical realization of photoelectrochemical water splitting is investigated using first-principles density functional theory incorporating the local density approximation and generalized gradient approximation plus the Hubbard U parameter formalism. Our calculations reveal that a relatively small concentration of Sb impurities is sufficient to achieve a significant narrowing of the band gap, enabling absorption of visible light. Theoretical results predict that Ga(Sb x)N 1-x alloys with 2-eV band gaps straddle the potential window at moderate to low pH values, thus indicating that dilute Ga(Sb x)N 1-x alloys could be potential candidates for splitting watermore » under visible light irradiation.« less

Platelet rich fibrin combined with decalcified freeze-dried bone allograft for the treatment of human intrabony periodontal defects: a randomized split mouth clinical trail.

PubMed

Agarwal, Ashish; Gupta, Narinder Dev; Jain, Avikal

2016-01-01

Polypeptide growth factors of platelet rich fibrin (PRF) have the potential to regenerate periodontal tissues. Osteoinductive property of demineralized freeze-dried bone allograft (DFDBA) has been successfully utilized in periodontal regeneration. The aim of the present randomized, split mouth, clinical trial was to determine the additive effects of PRF with a DFDBA in the treatment of human intrabony periodontal defects. Sixty interproximal infrabony defects in 30 healthy, non-smoker patients diagnosed with chronic periodontitis were randomly assigned to PRF/DFDBA group or the DFDBA/saline. Clinical [pocket depth (PD), clinical attachment level (CAL) and gingival recession (REC)] and radiographic (bone fill, defect resolution and alveolar crest resorption) measurements were made at baseline and at a 12-month evaluation. Compared with baseline, 12-month results indicated that both treatment modalities resulted in significant changes in all clinical and radiographic parameters. However, the PRP/DFDBA group exhibited statistically significantly greater changes compared with the DFDBA/saline group in PD (4.15 ± 0.84 vs 3.60 ± 0.51 mm), CAL (3.73 ± 0.74 vs 2.61 ± 0.68 mm), REC (0.47 ± 0.56 vs 1.00 ± 0.61 mm), bone fill (3.50 ± 0.67 vs 2.49 ± 0.64 mm) and defect resolution (3.73 ± 0.63 vs 2.75 ± 0.57 mm). Observations indicate that a combination of PRF and DFDBA is more effective than DFDBA with saline for the treatment of infrabony periodontal defects.

Sub-Doppler infrared spectroscopy of CH2OH radical in a slit supersonic jet: Vibration-rotation-tunneling dynamics in the symmetric CH stretch manifold

PubMed Central

Schuder, Michael D.; Wang, Fang; Chang, Chih-Hsuan; Nesbitt, David J.

2017-01-01

The sub-Doppler CH-symmetric stretch (ν3) infrared absorption spectrum of a hydroxymethyl (CH2OH) radical is observed and analyzed with the radical formed in a slit-jet supersonic discharge expansion (Trot = 18 K) via Cl atom mediated H atom abstraction from methanol. The high sensitivity of the spectrometer and reduced spectral congestion associated with the cooled expansion enable first infrared spectroscopic observation of hydroxymethyl transitions from both ± symmetry tunneling states resulting from large amplitude COH torsional motion. Nuclear spin statistics due to exchange of the two methyl H-atoms aid in unambiguous rovibrational assignment of two A-type Ka = 0 ← 0 and Ka = 1 ← 1 bands out of each ± tunneling state, with additional spectral information obtained from spin-rotation splittings in P, Q, and R branch Ka = 1 ← 1 transitions that become resolved at low N. A high level ab initio potential surface (CCSD(T)-f12b/cc-pvnzf12 (n = 2,3)/CBS) is calculated in the large amplitude COH torsional and CH2 wag coordinates, which in the adiabatic approximation and with zero point correction predicts ground state tunneling splittings in good qualitative agreement with experiment. Of particular astrochemical interest, a combined fit of the present infrared ground state combination differences with recently reported millimeter-wave frequencies permits the determination of improved accuracy rotational constants for the ground vibrational state, which will facilitate ongoing millimeter/microwave searches for a hydroxymethyl radical in the interstellar medium. PMID:28527463

The use of mucograft collagen matrix to augment the zone of keratinized tissue around teeth: a pilot study.

PubMed

Nevins, Myron; Nevins, Marc L; Kim, Soo-Woo; Schupbach, Peter; Kim, David M

2011-01-01

This prospective split-mouth pilot case series compared the use of a bilayer collagen matrix (CM) to an autogenous gingival graft (AGG) in the ability to increase the zone of keratinized attached gingiva. Five patients with inadequate amounts of keratinized attached gingiva bilaterally in the posterior mandible were enrolled using a split-mouth design. There were statistically significant increases in attached gingiva at all test (CM) and control (AGG) sites. The CM sites at 12 months blended well with surrounding tissues, while the AGG sites were morphologically dissimilar to the adjacent areas. Biopsy results showed intrapatient histologic similarity between CM and AGG treatments, with all sites exhibiting mature connective tissue covered by keratinized epithelium. Thus, the obtained data support further investigations in evaluating the role of CM as a viable alternative to AGG in augmenting areas deficient in keratinized gingiva.

Switching of bound vector solitons for the coupled nonlinear Schrödinger equations with nonhomogenously stochastic perturbations

NASA Astrophysics Data System (ADS)

Sun, Zhi-Yuan; Gao, Yi-Tian; Yu, Xin; Liu, Ying

2012-12-01

We investigate the dynamics of the bound vector solitons (BVSs) for the coupled nonlinear Schrödinger equations with the nonhomogenously stochastic perturbations added on their dispersion terms. Soliton switching (besides soliton breakup) can be observed between the two components of the BVSs. Rate of the maximum switched energy (absolute values) within the fixed propagation distance (about 10 periods of the BVSs) enhances in the sense of statistics when the amplitudes of stochastic perturbations increase. Additionally, it is revealed that the BVSs with enhanced coherence are more robust against the perturbations with nonhomogenous stochasticity. Diagram describing the approximate borders of the splitting and non-splitting areas is also given. Our results might be helpful in dynamics of the BVSs with stochastic noises in nonlinear optical fibers or with stochastic quantum fluctuations in Bose-Einstein condensates.

Switching of bound vector solitons for the coupled nonlinear Schrödinger equations with nonhomogenously stochastic perturbations.

PubMed

Sun, Zhi-Yuan; Gao, Yi-Tian; Yu, Xin; Liu, Ying

2012-12-01

We investigate the dynamics of the bound vector solitons (BVSs) for the coupled nonlinear Schrödinger equations with the nonhomogenously stochastic perturbations added on their dispersion terms. Soliton switching (besides soliton breakup) can be observed between the two components of the BVSs. Rate of the maximum switched energy (absolute values) within the fixed propagation distance (about 10 periods of the BVSs) enhances in the sense of statistics when the amplitudes of stochastic perturbations increase. Additionally, it is revealed that the BVSs with enhanced coherence are more robust against the perturbations with nonhomogenous stochasticity. Diagram describing the approximate borders of the splitting and non-splitting areas is also given. Our results might be helpful in dynamics of the BVSs with stochastic noises in nonlinear optical fibers or with stochastic quantum fluctuations in Bose-Einstein condensates.

Nuclear energy release from fragmentation

NASA Astrophysics Data System (ADS)

Li, Cheng; Souza, S. R.; Tsang, M. B.; Zhang, Feng-Shou

2016-08-01

It is well known that binary fission occurs with positive energy gain. In this article we examine the energetics of splitting uranium and thorium isotopes into various numbers of fragments (from two to eight) with nearly equal size. We find that the energy released by splitting 230,232Th and 235,238U into three equal size fragments is largest. The statistical multifragmentation model (SMM) is applied to calculate the probability of different breakup channels for excited nuclei. By weighing the probability distributions of fragment multiplicity at different excitation energies, we find the peaks of energy release for 230,232Th and 235,238U are around 0.7-0.75 MeV/u at excitation energy between 1.2 and 2 MeV/u in the primary breakup process. Taking into account the secondary de-excitation processes of primary fragments with the GEMINI code, these energy peaks fall to about 0.45 MeV/u.

Antecedent thermal injury worsens split-thickness skin graft quality: A clinically relevant porcine model of full-thickness burn, excision and grafting.

PubMed

Carlsson, Anders H; Rose, Lloyd F; Fletcher, John L; Wu, Jesse C; Leung, Kai P; Chan, Rodney K

2017-02-01

Current standard of care for full-thickness burn is excision followed by autologous split-thickness skin graft placement. Skin grafts are also frequently used to cover surgical wounds not amenable to linear closure. While all grafts have potential to contract, clinical observation suggests that antecedent thermal injury worsens contraction and impairs functional and aesthetic outcomes. This study evaluates the impact of antecedent full-thickness burn on split-thickness skin graft scar outcomes and the potential mediating factors. Full-thickness contact burns (100°C, 30s) were created on the backs of anesthetized female Yorkshire Pigs. After seven days, burn eschar was tangentially excised and covered with 12/1000th inch (300μm) split-thickness skin graft. For comparison, unburned wounds were created by sharp excision to fat before graft application. From 7 to 120days post-grafting, planimetric measurements, digital imaging and biopsies for histology, immunohistochemistry and gene expression were obtained. At 120days post-grafting, the Observer Scar Assessment Scale, colorimetry, contour analysis and optical graft height assessments were performed. Twenty-nine porcine wounds were analyzed. All measured metrics of clinical skin quality were significantly worse (p<0.05) in burn injured wounds. Histological analysis supported objective clinical findings with marked scar-like collagen proliferation within the dermis, increased vascular density, and prolonged and increased cellular infiltration. Observed differences in contracture also correlated with earlier and more prominent myofibroblast differentiation as demonstrated by α-SMA staining. Antecedent thermal injury worsens split-thickness skin graft quality, likely by multiple mechanisms including burn-related inflammation, microscopically inadequate excision, and dysregulation of tissue remodeling. A valid, reliable, clinically relevant model of full-thickness burn, excision and skin replacement therapy has been demonstrated. Future research to enhance quality of skin replacement therapies should be directed toward modulation of inflammation and assessments for complete excision. Copyright © 2016 Elsevier Ltd and ISBI. All rights reserved.

Single-layer group IV-V and group V-IV-III-VI semiconductors: Structural stability, electronic structures, optical properties, and photocatalysis

NASA Astrophysics Data System (ADS)

Lin, Jia-He; Zhang, Hong; Cheng, Xin-Lu; Miyamoto, Yoshiyuki

2017-07-01

Recently, single-layer group III monochalcogenides have attracted both theoretical and experimental interest at their potential applications in photonic devices, electronic devices, and solar energy conversion. Excited by this, we theoretically design two kinds of highly stable single-layer group IV-V (IV =Si ,Ge , and Sn; V =N and P) and group V-IV-III-VI (IV =Si ,Ge , and Sn; V =N and P; III =Al ,Ga , and In; VI =O and S) compounds with the same structures with single-layer group III monochalcogenides via first-principles simulations. By using accurate hybrid functional and quasiparticle methods, we show the single-layer group IV-V and group V-IV-III-VI are indirect bandgap semiconductors with their bandgaps and band edge positions conforming to the criteria of photocatalysts for water splitting. By applying a biaxial strain on single-layer group IV-V, single-layer group IV nitrides show a potential on mechanical sensors due to their bandgaps showing an almost linear response for strain. Furthermore, our calculations show that both single-layer group IV-V and group V-IV-III-VI have absorption from the visible light region to far-ultraviolet region, especially for single-layer SiN-AlO and SnN-InO, which have strong absorption in the visible light region, resulting in excellent potential for solar energy conversion and visible light photocatalytic water splitting. Our research provides valuable insight for finding more potential functional two-dimensional semiconductors applied in optoelectronics, solar energy conversion, and photocatalytic water splitting.

Comparative evaluation of stress levels before, during, and after periodontal surgical procedures with and without nitrous oxide-oxygen inhalation sedation

PubMed Central

Sandhu, Gurkirat; Khinda, Paramjit Kaur; Gill, Amarjit Singh; Singh Khinda, Vineet Inder; Baghi, Kamal; Chahal, Gurparkash Singh

2017-01-01

Context: Periodontal surgical procedures produce varying degree of stress in all patients. Nitrous oxide-oxygen inhalation sedation is very effective for adult patients with mild-to-moderate anxiety due to dental procedures and needle phobia. Aim: The present study was designed to perform periodontal surgical procedures under nitrous oxide-oxygen inhalation sedation and assess whether this technique actually reduces stress physiologically, in comparison to local anesthesia alone (LA) during lengthy periodontal surgical procedures. Settings and Design: This was a randomized, split-mouth, cross-over study. Materials and Methods: A total of 16 patients were selected for this randomized, split-mouth, cross-over study. One surgical session (SS) was performed under local anesthesia aided by nitrous oxide-oxygen inhalation sedation, and the other SS was performed on the contralateral quadrant under LA. For each session, blood samples to measure and evaluate serum cortisol levels were obtained, and vital parameters including blood pressure, heart rate, respiratory rate, and arterial blood oxygen saturation were monitored before, during, and after periodontal surgical procedures. Statistical Analysis Used: Paired t-test and repeated measure ANOVA. Results: The findings of the present study revealed a statistically significant decrease in serum cortisol levels, blood pressure and pulse rate and a statistically significant increase in respiratory rate and arterial blood oxygen saturation during periodontal surgical procedures under nitrous oxide inhalation sedation. Conclusion: Nitrous oxide-oxygen inhalation sedation for periodontal surgical procedures is capable of reducing stress physiologically, in comparison to LA during lengthy periodontal surgical procedures. PMID:29386796

Emergence of the interplay between hierarchy and contact splitting in biological adhesion highlighted through a hierarchical shear lag model.

PubMed

Brely, Lucas; Bosia, Federico; Pugno, Nicola M

2018-06-20

Contact unit size reduction is a widely studied mechanism as a means to improve adhesion in natural fibrillar systems, such as those observed in beetles or geckos. However, these animals also display complex structural features in the way the contact is subdivided in a hierarchical manner. Here, we study the influence of hierarchical fibrillar architectures on the load distribution over the contact elements of the adhesive system, and the corresponding delamination behaviour. We present an analytical model to derive the load distribution in a fibrillar system loaded in shear, including hierarchical splitting of contacts, i.e. a "hierarchical shear-lag" model that generalizes the well-known shear-lag model used in mechanics. The influence on the detachment process is investigated introducing a numerical procedure that allows the derivation of the maximum delamination force as a function of the considered geometry, including statistical variability of local adhesive energy. Our study suggests that contact splitting generates improved adhesion only in the ideal case of extremely compliant contacts. In real cases, to produce efficient adhesive performance, contact splitting needs to be coupled with hierarchical architectures to counterbalance high load concentrations resulting from contact unit size reduction, generating multiple delamination fronts and helping to avoid detrimental non-uniform load distributions. We show that these results can be summarized in a generalized adhesion scaling scheme for hierarchical structures, proving the beneficial effect of multiple hierarchical levels. The model can thus be used to predict the adhesive performance of hierarchical adhesive structures, as well as the mechanical behaviour of composite materials with hierarchical reinforcements.

TOTAL ORE PROCESSING INTEGRATION AND MANAGEMENT

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

Leslie Gertsch; Richard Gertsch

2005-05-16

The lessons learned from ore segregation test No.3 were presented to Minntac Mine personnel during the reporting period. Ore was segregated by A-Factor, with low values going to Step 1/2 and high values going to Step 3. During the test, the mine maintained the best split possible for the given production and location constraints. During the test, Step 1&2 A-Factor was lowered more than Step 3 was raised. All other ore quality changes were not manipulated, but the segregation by A-Factor affected most of the other qualities. Magnetic iron, coarse tails, fine tails, silica, and grind changed in response tomore » the split. Segregation was achieved by adding ore from HIS to the Step 3 blend and lowering the amount of LC 1&2 and somewhat lowering the amount of LC 3&4. Conversely, Step 1&2 received less HIS with a corresponding increase in LC 1&2. The amount of IBC was increased to both Steps about one-third of the way into the test. For about the center half of the test, LC 3&4 was reduced to both Steps. The most noticeable layer changes were, then: an increase in the HIS split; a decrease in the LC 1&2 split; adding IBC to both Steps; and lowering LC 3&4 to both Steps. Statistical analysis of the dataset collected during ordinary, non-segregated operation of the mine and mill is continuing. Graphical analysis of blast patterns according to drill monitor data was slowed by student classwork. It is expected to resume after the semester ends in May.« less

Continuous Aspirin Use Does Not Increase Bleeding Risk of Split-Thickness Skin Transplantation Repair to Chronic Wounds.

PubMed

Sun, Yanwei; Wang, Yibing; Li, Liang; Zhang, Zheng; Wang, Ning; Wu, Dan

Discontinuation of aspirin therapy before cutaneous surgery may cause serious complications. The aim of this prospective study was to evaluate the bleeding risk of split-thickness skin transplantation repair to chronic wounds in patients on aspirin therapy. A total of 97 patients who underwent split-thickness skin transplantation surgery of chronic wounds during a 2-year period were enrolled. They were categorized on the basis of aspirin therapies. The primary outcome was postoperative bleeding and bleeding complications. Univariate analysis was performed to examine the association between aspirin and bleeding complications. Among the 26 patients taking aspirin continuously in group A, there were 5 bleeding complications (19.23%). Among the 55 nonusers in group B, there were 10 bleeding complications (18.18%). Among the 16 discontinuous patients in group C, there were 3 bleeding complications (18.75%). No statistical differences were found among the groups ( P = .956). Univariate analysis showed that continuous aspirin use was not significantly associated with bleeding complications (odds ratio, 0.933; 95% confidence interval, 0.283-3.074; P = .910 in the aspirin and control groups) and that discontinuous aspirin use was not significantly associated with bleeding complications (odds ratio, 0.963; 95% confidence interval, 0.230-4.025; P = .959 in the aspirin and control groups; odds ratio, 0.969; 95% confidence interval, 0.198-4.752; P = .969 in the aspirin and discontinuous groups). Continuous aspirin use does not produce an additional bleeding risk in patients who undergo split-thickness skin transplantation repair of chronic wounds.

Using a Split-belt Treadmill to Evaluate Generalization of Human Locomotor Adaptation.

PubMed

Vasudevan, Erin V L; Hamzey, Rami J; Kirk, Eileen M

2017-08-23

Understanding the mechanisms underlying locomotor learning helps researchers and clinicians optimize gait retraining as part of motor rehabilitation. However, studying human locomotor learning can be challenging. During infancy and childhood, the neuromuscular system is quite immature, and it is unlikely that locomotor learning during early stages of development is governed by the same mechanisms as in adulthood. By the time humans reach maturity, they are so proficient at walking that it is difficult to come up with a sufficiently novel task to study de novo locomotor learning. The split-belt treadmill, which has two belts that can drive each leg at a different speed, enables the study of both short- (i.e., immediate) and long-term (i.e., over minutes-days; a form of motor learning) gait modifications in response to a novel change in the walking environment. Individuals can easily be screened for previous exposure to the split-belt treadmill, thus ensuring that all experimental participants have no (or equivalent) prior experience. This paper describes a typical split-belt treadmill adaptation protocol that incorporates testing methods to quantify locomotor learning and generalization of this learning to other walking contexts. A discussion of important considerations for designing split-belt treadmill experiments follows, including factors like treadmill belt speeds, rest breaks, and distractors. Additionally, potential but understudied confounding variables (e.g., arm movements, prior experience) are considered in the discussion.

Flavonoid and leaf gas exchange responses of Centella asiatica to acute gamma irradiation and carbon dioxide enrichment under controlled environment conditions.

PubMed

Moghaddam, Sina Siavash; Jaafar, Hawa Binti; Aziz, Maheran Abdul; Ibrahim, Rusli; Rahmat, Asmah Bt; Philip, Elizabeth

2011-10-25

The study was couducted to investigate the effects of gamma irradiation and CO₂ on flavonoid content and leaf gas exchange in C.asiatica. For flavonoid determination, the design was a split split plot based on Randomized Complete Block Design (RCBD). For other parameters, the designs were split plots. Statistical tests revealed significant differences in flavonoid contents of Centella asiatica leaves between different growth stages and various CO₂ treatments. CO₂ 400, G20 (400 = ambient CO₂; G20 = Plants exposed to 20 Gy) showed 82.90% higher total flavonoid content (TFC) in the 5th week than CO₂ 400 as control at its best harvest time (4th week). Increasing the concentration of CO₂ from 400 to 800 μmol/mol had significant effects on TFC and harvesting time. In fact, 800 μmol/mol resulted in 171.1% and 66.62% increases in TFC for control and irradiated plants, respectively. Moreover, increasing CO₂ concentration reduced the harvesting time to three and four weeks for control and irradiated plants, respectively. Enhancing CO₂ to 800 µmol/mol resulted in a 193.30% (CO₂ 800) increase in leaf biomass compared to 400 µmol/mol and 226.34% enhancement in irradiated plants (CO₂ 800, G20) [800 = Ambient CO₂; G20 = Plants exposed to 20 Gy] than CO₂ 400, G20. In addition, the CO₂ 800, G20 had the highest amount of flavonoid*biomass in the 4th week. The results of this study indicated that all elevated CO₂ treatments had higher PN than the ambient ones. The findings showed that when CO₂ level increased from 400 to 800 µmol/mol, stomatal conductance, leaf intercellular CO₂ and transpiration rate had the tendency to decrease. However, water use efficiency increased in response to elevated CO₂ concentration. Returning to the findings of this study, it is now possible to state that the proposed method (combined CO₂ and gamma irradiation) has the potential to increase the product value by reducing the time to harvest, increasing the yield per unit area via boosting photosynthesis capacity, as well as increasing biochemicals (flavonoids) per gram DM.

Monte Carlo isotopic inventory analysis for complex nuclear systems

NASA Astrophysics Data System (ADS)

Phruksarojanakun, Phiphat

Monte Carlo Inventory Simulation Engine (MCise) is a newly developed method for calculating isotopic inventory of materials. It offers the promise of modeling materials with complex processes and irradiation histories, which pose challenges for current, deterministic tools, and has strong analogies to Monte Carlo (MC) neutral particle transport. The analog method, including considerations for simple, complex and loop flows, is fully developed. In addition, six variance reduction tools provide unique capabilities of MCise to improve statistical precision of MC simulations. Forced Reaction forces an atom to undergo a desired number of reactions in a given irradiation environment. Biased Reaction Branching primarily focuses on improving statistical results of the isotopes that are produced from rare reaction pathways. Biased Source Sampling aims at increasing frequencies of sampling rare initial isotopes as the starting particles. Reaction Path Splitting increases the population by splitting the atom at each reaction point, creating one new atom for each decay or transmutation product. Delta Tracking is recommended for high-frequency pulsing to reduce the computing time. Lastly, Weight Window is introduced as a strategy to decrease large deviations of weight due to the uses of variance reduction techniques. A figure of merit is necessary to compare the efficiency of different variance reduction techniques. A number of possibilities for figure of merit are explored, two of which are robust and subsequently used. One is based on the relative error of a known target isotope (1/R 2T) and the other on the overall detection limit corrected by the relative error (1/DkR 2T). An automated Adaptive Variance-reduction Adjustment (AVA) tool is developed to iteratively define parameters for some variance reduction techniques in a problem with a target isotope. Sample problems demonstrate that AVA improves both precision and accuracy of a target result in an efficient manner. Potential applications of MCise include molten salt fueled reactors and liquid breeders in fusion blankets. As an example, the inventory analysis of a liquid actinide fuel in the In-Zinerator, a sub-critical power reactor driven by a fusion source, is examined. The result reassures MCise as a reliable tool for inventory analysis of complex nuclear systems.

Estimating sleep parameters using nasal pressure signals applicable to continuous positive airway pressure devices.

PubMed

Park, Jong-Uk; Erdenebayar, Urtnasan; Joo, Eun-Yeon; Lee, Kyoung-Joung

2017-06-27

This paper proposes a method for classifying sleep-wakefulness and estimating sleep parameters using nasal pressure signals applicable to a continuous positive airway pressure (CPAP) device. In order to classify the sleep-wakefulness states of patients with sleep-disordered breathing (SDB), apnea-hypopnea and snoring events are first detected. Epochs detected as SDB are classified as sleep, and time-domain- and frequency-domain-based features are extracted from the epochs that are detected as normal breathing. Subsequently, sleep-wakefulness is classified using a support vector machine (SVM) classifier in the normal breathing epoch. Finally, four sleep parameters-sleep onset, wake after sleep onset, total sleep time and sleep efficiency-are estimated based on the classified sleep-wakefulness. In order to develop and test the algorithm, 110 patients diagnosed with SDB participated in this study. Ninety of the subjects underwent full-night polysomnography (PSG) and twenty underwent split-night PSG. The subjects were divided into 50 patients of a training set (full/split: 42/8), 30 of a validation set (full/split: 24/6) and 30 of a test set (full/split: 24/6). In the experiments conducted, sleep-wakefulness classification accuracy was found to be 83.2% in the test set, compared with the PSG scoring results of clinical experts. Furthermore, all four sleep parameters showed higher correlations than the results obtained via PSG (r  ⩾  0.84, p  <  0.05). In order to determine whether the proposed method is applicable to CPAP, sleep-wakefulness classification performances were evaluated for each CPAP in the split-night PSG data. The results indicate that the accuracy and sensitivity of sleep-wakefulness classification by CPAP variation shows no statistically significant difference (p  <  0.05). The contributions made in this study are applicable to the automatic classification of sleep-wakefulness states in CPAP devices and evaluation of the quality of sleep.

Photoelectrochemical water splitting in separate oxygen and hydrogen cells

NASA Astrophysics Data System (ADS)

Landman, Avigail; Dotan, Hen; Shter, Gennady E.; Wullenkord, Michael; Houaijia, Anis; Maljusch, Artjom; Grader, Gideon S.; Rothschild, Avner

2017-06-01

Solar water splitting provides a promising path for sustainable hydrogen production and solar energy storage. One of the greatest challenges towards large-scale utilization of this technology is reducing the hydrogen production cost. The conventional electrolyser architecture, where hydrogen and oxygen are co-produced in the same cell, gives rise to critical challenges in photoelectrochemical water splitting cells that directly convert solar energy and water to hydrogen. Here we overcome these challenges by separating the hydrogen and oxygen cells. The ion exchange in our cells is mediated by auxiliary electrodes, and the cells are connected to each other only by metal wires, enabling centralized hydrogen production. We demonstrate hydrogen generation in separate cells with solar-to-hydrogen conversion efficiency of 7.5%, which can readily surpass 10% using standard commercial components. A basic cost comparison shows that our approach is competitive with conventional photoelectrochemical systems, enabling safe and potentially affordable solar hydrogen production.

A state interaction spin-orbit coupling density matrix renormalization group method

NASA Astrophysics Data System (ADS)

Sayfutyarova, Elvira R.; Chan, Garnet Kin-Lic

2016-06-01

We describe a state interaction spin-orbit (SISO) coupling method using density matrix renormalization group (DMRG) wavefunctions and the spin-orbit mean-field (SOMF) operator. We implement our DMRG-SISO scheme using a spin-adapted algorithm that computes transition density matrices between arbitrary matrix product states. To demonstrate the potential of the DMRG-SISO scheme we present accurate benchmark calculations for the zero-field splitting of the copper and gold atoms, comparing to earlier complete active space self-consistent-field and second-order complete active space perturbation theory results in the same basis. We also compute the effects of spin-orbit coupling on the spin-ladder of the iron-sulfur dimer complex [Fe2S2(SCH3)4]3-, determining the splitting of the lowest quartet and sextet states. We find that the magnitude of the zero-field splitting for the higher quartet and sextet states approaches a significant fraction of the Heisenberg exchange parameter.

Materials-Related Aspects of Thermochemical Water and Carbon Dioxide Splitting: A Review

PubMed Central

Roeb, Martin; Neises, Martina; Monnerie, Nathalie; Call, Friedemann; Simon, Heike; Sattler, Christian; Schmücker, Martin; Pitz-Paal, Robert

2012-01-01

Thermochemical multistep water- and CO2-splitting processes are promising options to face future energy problems. Particularly, the possible incorporation of solar power makes these processes sustainable and environmentally attractive since only water, CO2 and solar power are used; the concentrated solar energy is converted into storable and transportable fuels. One of the major barriers to technological success is the identification of suitable active materials like catalysts and redox materials exhibiting satisfactory durability, reactivity and efficiencies. Moreover, materials play an important role in the construction of key components and for the implementation in commercial solar plants. The most promising thermochemical water- and CO2-splitting processes are being described and discussed with respect to further development and future potential. The main materials-related challenges of those processes are being analyzed. Technical approaches and development progress in terms of solving them are addressed and assessed in this review.

Suppression of the overlap between Majorana fermions by orbital magnetic effects in semiconducting-superconducting nanowires

NASA Astrophysics Data System (ADS)

Dmytruk, Olesia; Klinovaja, Jelena

2018-04-01

We study both analytically and numerically the role of orbital effects caused by a magnetic field applied along the axis of a semiconducting Rashba nanowire in the topological regime hosting Majorana fermions. We demonstrate that the orbital effects can be effectively taken into account in a one-dimensional model by shifting the chemical potential and thus modifying the topological criterion. We focus on the energy splitting between two Majorana fermions in a finite nanowire and find a striking interplay between orbital and Zeeman effects on this splitting. In the limit of strong spin-orbit interaction, we find regimes where the amplitude of the oscillating splitting stays constant or even decays with increasing the magnetic field, in stark contrast to the commonly studied case where orbital effects of the magnetic field are neglected. The period of these oscillations is found to be almost constant in many parameter regimes.

Improvement of efficiency in graphene/gallium nitride nanowire on Silicon photoelectrode for overall water splitting

NASA Astrophysics Data System (ADS)

Bae, Hyojung; Rho, Hokyun; Min, Jung-Wook; Lee, Yong-Tak; Lee, Sang Hyun; Fujii, Katsushi; Lee, Hyo-Jong; Ha, Jun-Seok

2017-11-01

Gallium nitride (GaN) nanowires are one of the most promising photoelectrode materials due to their high stability in acidic and basic electrolytes, and tunable band edge potentials. In this study, GaN nanowire arrays (GaN NWs) were prepared by molecular beam epitaxy (MBE); their large surface area enhanced the solar to hydrogen conversion efficiency. More significantly, graphene was grown by chemical vapor deposition (CVD), which enhanced the electron transfer between NWs for water splitting and protected the GaN NW surface. Structural characterizations of the prepared composite were performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocurrent density of Gr/GaN NWs exhibited a two-fold increase over pristine GaN NWs and sustained water splitting up to 70 min. These improvements may accelerate possible applications for hydrogen generation with high solar to hydrogen conversion efficiency.

A search for muon neutrino to electron neutrino oscillation mediated by sterile neutrinos in MINOS+

NASA Astrophysics Data System (ADS)

Germani, Stefano; Schreckenberger, Adam P.

2017-09-01

The MINOS experiment made precision measurements of the neutrino oscillation parameters that are governed by the atmospheric mass-squared splitting. These measurements were made with data that were collected while the NuMI muon neutrino beam operated in a low energy mode that peaks around 3 GeV. Today the NuMI beam is running with a higher energy mode that produces a neutrino energy spectrum that peaks around 7 GeV, allowing the MINOS+ experiment to probe neutrino oscillation phenomena that could potentially be governed by a fourth mass-squared splitting. If observed, the presence of a fourth mass-squared splitting would be compelling evidence for a sterile neutrino state. In this analysis, we will present the results of a search for νµ → νe oscillation mediated by sterile neutrinos in MINOS+. The results will be contrasted against the measurements made by the LSND experiment.

Biomechanical analysis of posteromedial tibial plateau split fracture fixation.

PubMed

Zeng, Zhi-Min; Luo, Cong-Feng; Putnis, Sven; Zeng, Bing-Fang

2011-01-01

The purpose of this study was to compare the biomechanical strength of four different fixation methods for a posteromedial tibial plateau split fracture. Twenty-eight tibial plateau fractures were simulated using right-sided synthetic tibiae models. Each fracture model was randomly instrumented with one of the four following constructs, anteroposterior lag-screws, an anteromedial limited contact dynamic compression plate (LC-DCP), a lateral locking plate, or a posterior T-shaped buttress plate. Vertical subsidence of the posteromedial fragment was measured from 500 N to 1500 N during biomechanical testing, the maximum load to failure was also determined. It was found that the posterior T-shaped buttress plate allowed the least subsidence of the posteromedial fragment and produced the highest mean failure load than each of the other three constructs (P=0.00). There was no statistical significant difference between using lag screws or an anteromedial LC-DCP construct for the vertical subsidence at a 1500 N load and the load to failure (P>0.05). This study showed that a posterior-based buttress technique is biomechanically the most stable in-vitro fixation method for posteromedial split tibial plateau fractures, with AP screws and anteromedial-based LC-DCP are not as stable for this type of fracture. Copyright © 2010 Elsevier B.V. All rights reserved.

Artificial intelligence analysis of hyperspectral remote sensing data for management of water, weed, and nitrogen stresses in corn fields

NASA Astrophysics Data System (ADS)

Waheed, Tahir

This study investigated the possibility of using ground-based remotely sensed hyperspectral observations with a special emphasis on detection of water, weed and nitrogen stresses contributing towards in-season decision support for precision crop management (PCM). A three factor split-split-plot experiment, with four randomized blocks as replicates, was established during the growing seasons of 2003 and 2004. Corn (Zea mays L.) hybrid DKC42-22 was grown because this hybrid is a good performer on light soils in Quebec. There were twelve 12 x 12m plots in a block (one replication per treatment per block) and the total number of plots was 48. Water stress was the main factor in the experiment. A drip irrigation system was laid out and each block was split into irrigated and non-irrigated halves. The second main factor of the experiment was weeds with two levels i.e. full weed control and no weed control. Weed treatments were assigned randomly by further splitting the irrigated and non-irrigated sub-blocks into two halves. Each of the weed treatments was furthermore split into three equal sub-sub-plots for nitrogen treatments (third factor of the experiment). Nitrogen was applied at three levels i.e. 50, 150 and 250 kg N ha-1 (Quebec norm is between 120-160 kg N ha-1). The hyperspectral data were recorded (spectral resolution = 1 nm) mid-day (between 1000 and 1400 hours) with a FieldSpec FR spectroradiometer over a spectral range of 400-2500 run at three growth stages namely: early growth, tasseling and full maturity, in each of the growing season. There are two major original contributions in this thesis: First is the development of a hyperspectral data analysis procedure for separating visible (400-700 nm), near-infrared (700-1300 nm) and mid-infrared (1300-2500 nm) regions of the spectrum for use in discriminant analysis procedure. In addition, of all the spectral band-widths analyzed, seven waveband-aggregates were identified using STEPDISC procedure, which were the most effective for classifying combined water, weed, and nitrogen stress. The second contribution is the successful classification of hyperspectral observations acquired over an agricultural field, using three innovative artificial intelligence approaches; support vector machines (SVM), genetic algorithms (GA) and decision tree (DT) algorithms. These AI approaches were used to evaluate a combined effect of water, weed and nitrogen stresses in corn and of all the three AI approaches used, SVM produced the best results (overall accuracy ranging from 88% to 100%). The general conclusion is that the conventional statistical and artificial intelligence techniques used in this study are all useful for quickly mapping combined affects of irrigation, weed and nitrogen stresses (with overall accuracies ranging from 76% to 100%). These approaches have strong potential and are of great benefit to those investigating the in-season impact of irrigation, weed and nitrogen management for corn crop production and other environment related challenges.

Willingness-to-pay function for two fuel treatments to reduce wildfire acreage burned: A scope test and comparison of white and hispanic households

Treesearch

John B. Loomis; Hung Le Trong; Armando González-Cabán

2009-01-01

We estimate a marginal benefit function for using prescribed burning and mechanical fuel reduction programs to reduce acres burned by wildfire in three states. Since each state had different acre reductions, a statistically significant coefficient on the reduction in acres burned is also a split sample scope test frequently used as an indicator of the internal validity...

Assessment of Acridine Orange and SYTO 16 for in vivo imaging of the peritoneal tissues in mice

PubMed Central

Udovich, Joshua Anthony; Besselsen, David G.; Gmitro, Arthur F.

2009-01-01

The effect of peritoneal injection of Acridine Orange (AO) and SYTO 16 in mice was investigated. Images of peritoneal tissues stained with these dyes and obtained through a confocal microendoscope are presented. Seventy-five Balb/c mice were split into five groups and given peritoneal injections of dye or saline. The proportions of negative outcomes in each group were compared using confidence intervals and the Fisher's exact statistical test. A statistically significant increase in adverse events due to dye injection was not observed.These data provide an initial investigation into the safety of AO and SYTO 16 for in vivo imaging. PMID:19397741

Motorcycle lane-sharing : literature review.

DOT National Transportation Integrated Search

2010-06-01

This report examines the use of lane-sharing (also sometimes referred to as lane-splitting and filtering) nationally and internationally and includes discussions on motorcycle and driver (auto) safety, and the potential benefits of lane-sharing.

Traditional neighborhood development (TND) guidelines

DOT National Transportation Integrated Search

2000-08-01

A Traditional Neighborhood Development (TND) is a human scale, walkable community with moderate to high residential densities and a mixed use core. Compared with conventional suburban developments, TNDs have a higher potential to increase modal split...

Band edge engineering of oxide photoanodes for photoelectrochemical water splitting: Integration of subsurface dipoles with atomic-scale control

DOE PAGES

Hikita, Yasuyuki; Nishio, Kazunori; Seitz, Linsey C.; ...

2016-01-22

One of the crucial parameters dictating the efficiency of photoelectrochemical water-splitting is the semiconductor band edge alignment with respect to hydrogen and oxygen redox potentials. Despite the importance of metal oxides in their use as photoelectrodes, studies to control the band edge alignment in aqueous solution have been limited predominantly to compound semiconductors with modulation ranges limited to a few hundred mV. The ability to modulate the flat band potential of oxide photoanodes by as much as 1.3 V, using the insertion of subsurface electrostatic dipoles near a Nb-doped SrTiO 3/aqueous electrolyte interface is reported. Lastly, the tunable range achievedmore » far exceeds previous reports in any semiconductor/aqueous electrolyte system and suggests a general design strategy for highly efficient oxide photoelectrodes.« less

Neutron-proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon-nucleus scattering data within an isospin dependent optical model

NASA Astrophysics Data System (ADS)

Li, Xiao-Hua; Guo, Wen-Jun; Li, Bao-An; Chen, Lie-Wen; Fattoyev, Farrukh J.; Newton, William G.

2015-04-01

The neutron-proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be mn-p* ≡ (mn* - mp*) / m = (0.41 ± 0.15) δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependence of the nucleon isovector potential necessary for understanding novel structures and reactions of rare isotopes.

Carbon Nanotube-Based Membrane for Light-Driven, Simultaneous Proton and Electron Transport

DOE PAGES

Pilgrim, Gregory A.; Amori, Amanda R.; Hou, Zhentao; ...

2016-12-07

Here we discuss the photon driven transport of protons and electrons over hundreds of microns through a membrane based on vertically aligned single walled carbon nanotubes (SWNTs). Electrons are photogenerated in colloidal CdSe quantum dots that have been noncovalently attached to the carbon nanotube membrane and can be delivered at potentials capable of reducing earth-abundant molecular catalysts that perform proton reduction. Proton transport is driven by the electron photocurrent and is shown to be faster through the SWNT based membrane than through the commercial polymer Nafion. Furthermore, the potential utility of SWNT membranes for solar water splitting applications is demonstratedmore » through their excellent proton and electron transport properties as well as their ability to interact with other components of water splitting systems, such as small molecule electron acceptors.« less

Assessing the utility of bipolar membranes for use in photoelectrochemical water-splitting cells.

PubMed

Vargas-Barbosa, Nella M; Geise, Geoffrey M; Hickner, Michael A; Mallouk, Thomas E

2014-11-01

Membranes are important in water-splitting solar cells because they prevent crossover of hydrogen and oxygen. Here, bipolar membranes (BPMs) were tested as separators in water electrolysis cells. Steady-state membrane and solution resistances, electrode overpotentials, and pH gradients were measured at current densities relevant to solar photoelectrolysis. Under forward bias conditions, electrodialysis of phosphate buffer ions creates a pH gradient across a BPM. Under reverse bias, the BPM can maintain a constant buffer pH on both sides of the cell, but a large membrane potential develops. Thus, the BPM does not present a viable solution for electrolysis in buffered electrolytes. However, the membrane potential is minimized when the anode and cathode compartments of the cell contain strongly basic and acidic electrolytes, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Giant onsite electronic entropy enhances the performance of ceria for water splitting.

PubMed

Naghavi, S Shahab; Emery, Antoine A; Hansen, Heine A; Zhou, Fei; Ozolins, Vidvuds; Wolverton, Chris

2017-08-18

Previous studies have shown that a large solid-state entropy of reduction increases the thermodynamic efficiency of metal oxides, such as ceria, for two-step thermochemical water splitting cycles. In this context, the configurational entropy arising from oxygen off-stoichiometry in the oxide, has been the focus of most previous work. Here we report a different source of entropy, the onsite electronic configurational entropy, arising from coupling between orbital and spin angular momenta in lanthanide f orbitals. We find that onsite electronic configurational entropy is sizable in all lanthanides, and reaches a maximum value of ≈4.7 k B per oxygen vacancy for Ce 4+ /Ce 3+ reduction. This unique and large positive entropy source in ceria explains its excellent performance for high-temperature catalytic redox reactions such as water splitting. Our calculations also show that terbium dioxide has a high electronic entropy and thus could also be a potential candidate for solar thermochemical reactions.Solid-state entropy of reduction increases the thermodynamic efficiency of ceria for two-step thermochemical water splitting. Here, the authors report a large and different source of entropy, the onsite electronic configurational entropy arising from coupling between orbital and spin angular momenta in f orbitals.

Flow of foams in two-dimensional disordered porous media

NASA Astrophysics Data System (ADS)

Dollet, Benjamin; Geraud, Baudouin; Jones, Sian A.; Meheust, Yves; Cantat, Isabelle; Institut de Physique de Rennes Team; Geosciences Rennes Team

2015-11-01

Liquid foams are a yield stress fluid with elastic properties. When a foam flow is confined by solid walls, viscous dissipation arises from the contact zones between soap films and walls, giving very peculiar friction laws. In particular, foams potentially invade narrow pores much more efficiently than Newtonian fluids, which is of great importance for enhanced oil recovery. To quantify this effect, we study experimentally flows of foam in a model two-dimensional porous medium, consisting of an assembly of circular obstacles placed randomly in a Hele-Shaw cell, and use image analysis to quantify foam flow at the local scale. We show that bubbles split as they flow through the porous medium, by a mechanism of film pinching during contact with an obstacle, yielding two daughter bubbles per split bubble. We quantify the evolution of the bubble size distribution as a function of the distance along the porous medium, the splitting probability as a function of bubble size, and the probability distribution function of the daughter bubbles. We propose an evolution equation to model this splitting phenomenon and compare it successfully to the experiments, showing how at long distance, the porous medium itself dictates the size distribution of the foam.

Splitting a droplet for femtoliter liquid patterns and single cell isolation.

PubMed

Li, Huizeng; Yang, Qiang; Li, Guannan; Li, Mingzhu; Wang, Shutao; Song, Yanlin

2015-05-06

Well-defined microdroplet generation has attracted great interest, which is important for the high-resolution patterning and matrix distribution for chemical reactions and biological assays. By sliding a droplet on a patterned superhydrophilic/superhydrophobic substrate, tiny microdroplet arrays low to femtoliter were achieved with uniform volume and composition. Using this method, cells were successfully isolated, resulting in a single cell array. The droplet-splitting method is facile, sample-effective, and low-cost, which will be of great potential for the development of microdroplet arrays for biological analysis as well as patterning system and devices.

Search for Stopped Gluinos during Beam-off Periods at CMS

NASA Astrophysics Data System (ADS)

Rossato, Kenneth

2010-02-01

Several models of new physics, including split supersymmetry, predict the existence of a heavy particle which is long-lived on timescales of the bunch spacing of the LHC. Such particles may be slowed through dE/dx losses and stop in the volume of the CMS detector before ultimately decaying. We describe a search strategy that employs a special jet trigger to look for energy depositions in the hadronic calorimeter during time periods without pp collisions. We examine the potential for discovery and exclusion of gluinos in split supersymmetry in early running of the LHC. )

Production and detection of atomic hexadecapole at Earth's magnetic field.

PubMed

Acosta, V M; Auzinsh, M; Gawlik, W; Grisins, P; Higbie, J M; Jackson Kimball, D F; Krzemien, L; Ledbetter, M P; Pustelny, S; Rochester, S M; Yashchuk, V V; Budker, D

2008-07-21

Optical magnetometers measure magnetic fields with extremely high precision and without cryogenics. However, at geomagnetic fields, important for applications from landmine removal to archaeology, they suffer from nonlinear Zeeman splitting, leading to systematic dependence on sensor orientation. We present experimental results on a method of eliminating this systematic error, using the hexadecapole atomic polarization moment. In particular, we demonstrate selective production of the atomic hexadecapole moment at Earth's magnetic field and verify its immunity to nonlinear Zeeman splitting. This technique promises to eliminate directional errors in all-optical atomic magnetometers, potentially improving their measurement accuracy by several orders of magnitude.

Investigation of mantle kinematics beneath the Hellenic-subduction zone with teleseismic direct shear waves

NASA Astrophysics Data System (ADS)

Confal, Judith M.; Eken, Tuna; Tilmann, Frederik; Yolsal-Çevikbilen, Seda; Çubuk-Sabuncu, Yeşim; Saygin, Erdinc; Taymaz, Tuncay

2016-12-01

The subduction and roll-back of the African plate beneath the Eurasian plate along the arcuate Hellenic trench is the dominant geodynamic process in the Aegean and western Anatolia. Mantle flow and lithospheric kinematics in this region can potentially be understood better by mapping seismic anisotropy. This study uses direct shear-wave splitting measurements based on the Reference Station Technique in the southern Aegean Sea to reveal seismic anisotropy in the mantle. The technique overcomes possible contamination from source-side anisotropy on direct S-wave signals recorded at a station pair by maximizing the correlation between the seismic traces at reference and target stations after correcting the reference stations for known receiver-side anisotropy and the target stations for arbitrary splitting parameters probed via a grid search. We obtained splitting parameters at 35 stations with good-quality S-wave signals extracted from 81 teleseismic events. Employing direct S-waves enabled more stable and reliable splitting measurements than previously possible, based on sparse SKS data at temporary stations, with one to five events for local SKS studies, compared with an average of 12 events for each station in this study. The fast polarization directions mostly show NNE-SSW orientation with splitting time delays between 1.15 s and 1.62 s. Two stations in the west close to the Hellenic Trench and one in the east show N-S oriented fast polarizations. In the back-arc region three stations exhibit NE-SW orientation. The overall fast polarization variations tend to be similar to those obtained from previous SKS splitting studies in the region but indicate a more consistent pattern, most likely due to the usage of a larger number of individual observations in direct S-wave derived splitting measurements. Splitting analysis on direct shear waves typically resulted in larger split time delays compared to previous studies, possibly because S-waves travel along a longer path in the same anisotropic structure. Considering the S-derived splitting measurements of this study together with earlier SKS and Rayleigh wave anisotropy modelling results we suggest that the very consistent direct S-derived fast shear wave directions can be explained by the lattice-preferred orientation of olivine in the asthenospheric mantle due to mantle flow induced by the roll-back of the slab. It is possible that a small contribution originated in the lower crust beneath the study region where anisotropic fabric might have formed in response to extension in the Miocene.

Model identification using stochastic differential equation grey-box models in diabetes.

PubMed

Duun-Henriksen, Anne Katrine; Schmidt, Signe; Røge, Rikke Meldgaard; Møller, Jonas Bech; Nørgaard, Kirsten; Jørgensen, John Bagterp; Madsen, Henrik

2013-03-01

The acceptance of virtual preclinical testing of control algorithms is growing and thus also the need for robust and reliable models. Models based on ordinary differential equations (ODEs) can rarely be validated with standard statistical tools. Stochastic differential equations (SDEs) offer the possibility of building models that can be validated statistically and that are capable of predicting not only a realistic trajectory, but also the uncertainty of the prediction. In an SDE, the prediction error is split into two noise terms. This separation ensures that the errors are uncorrelated and provides the possibility to pinpoint model deficiencies. An identifiable model of the glucoregulatory system in a type 1 diabetes mellitus (T1DM) patient is used as the basis for development of a stochastic-differential-equation-based grey-box model (SDE-GB). The parameters are estimated on clinical data from four T1DM patients. The optimal SDE-GB is determined from likelihood-ratio tests. Finally, parameter tracking is used to track the variation in the "time to peak of meal response" parameter. We found that the transformation of the ODE model into an SDE-GB resulted in a significant improvement in the prediction and uncorrelated errors. Tracking of the "peak time of meal absorption" parameter showed that the absorption rate varied according to meal type. This study shows the potential of using SDE-GBs in diabetes modeling. Improved model predictions were obtained due to the separation of the prediction error. SDE-GBs offer a solid framework for using statistical tools for model validation and model development. © 2013 Diabetes Technology Society.

New Statistical Model for Variability of Aerosol Optical Thickness: Theory and Application to MODIS Data over Ocean

NASA Technical Reports Server (NTRS)

Alexandrov, Mikhail Dmitrievic; Geogdzhayev, Igor V.; Tsigaridis, Konstantinos; Marshak, Alexander; Levy, Robert; Cairns, Brian

2016-01-01

A novel model for the variability in aerosol optical thickness (AOT) is presented. This model is based on the consideration of AOT fields as realizations of a stochastic process, that is the exponent of an underlying Gaussian process with a specific autocorrelation function. In this approach AOT fields have lognormal PDFs and structure functions having the correct asymptotic behavior at large scales. The latter is an advantage compared with fractal (scale-invariant) approaches. The simple analytical form of the structure function in the proposed model facilitates its use for the parameterization of AOT statistics derived from remote sensing data. The new approach is illustrated using a month-long global MODIS AOT dataset (over ocean) with 10 km resolution. It was used to compute AOT statistics for sample cells forming a grid with 5deg spacing. The observed shapes of the structure functions indicated that in a large number of cases the AOT variability is split into two regimes that exhibit different patterns of behavior: small-scale stationary processes and trends reflecting variations at larger scales. The small-scale patterns are suggested to be generated by local aerosols within the marine boundary layer, while the large-scale trends are indicative of elevated aerosols transported from remote continental sources. This assumption is evaluated by comparison of the geographical distributions of these patterns derived from MODIS data with those obtained from the GISS GCM. This study shows considerable potential to enhance comparisons between remote sensing datasets and climate models beyond regional mean AOTs.

Strategists and Non-Strategists in Austrian Enterprises—Statistical Approaches

NASA Astrophysics Data System (ADS)

Duller, Christine

2011-09-01

The purpose of this work is to determine with a modern statistical approach which variables can indicate whether an arbitrary enterprise uses strategic management as basic business concept. "Strategic management is an ongoing process that evaluates and controls the business and the industries in which the company is involved; assesses its competitors and sets goals and strategies to meet all existing and potential competitors; and then reassesses each strategy annually or quarterly (i.e. regularly) to determine how it has been implemented and whether it has succeeded or needs replacement by a new strategy to meet changed circumstances, new technology, new competitors, a new economic environment or a new social, financial or political environment." [12] In Austria 70% to 80% of all enterprises can be classified as family firms. In literature the empirically untested hypothesis can be found that family firms tend to have less formalised management accounting systems than non-family enterprises. But it is unknown whether the use of strategic management accounting systems is influenced more by the fact of structure (family or non-family enterprise) or by the effect of size (number of employees). Therefore, the goal is to split up enterprises into two subgroups, namely strategists and non-strategists and to get information on the variables of influence (size, structure, branches, etc.). Two statistical approaches are used: On the one hand a classical cluster analysis is implemented to design two subgroups and on the other hand a latent class model is built up for this problem. After a description of the theoretical background first results of both strategies are compared.

Pre-stack separation of PP and split PS waves in HTI media

NASA Astrophysics Data System (ADS)

Lu, Jun; Wang, Yun; Yang, Yuyong; Chen, Jingyi

2017-07-01

Separation of PP and split PS waves in transversely isotropic media with a horizontal axis of symmetry is crucial for imaging subsurface targets and for fracture prediction in a multicomponent seismic survey using P-wave sources. In conventional multicomponent processing, when a low velocity zone is present near the surface, it is often assumed that the vertical Z-component mainly records P modes and that the horizontal X- and Y-components record S modes, including split PS waves. However, this assumption does not hold when the ubiquitous presence of azimuthal anisotropy makes near surface velocity structures more complicated. Seismic wavefields recorded in each component therefore generally represent a complex waveform formed by PP and split PS waves, seriously distorting velocity analysis and seismic imaging. Most previous studies on wave separation have tended to separate P and S modes using pre-stack data and to separate split S modes using post-stack sections, under the assumption of orthogonal polarization. However, split S modes can hardly maintain their original orthogonal polarizations during propagation to the surface due to stratigraphic heterogeneity. Here, without assuming orthogonal polarization, we present a method for pre-stack separation of PP, PS1 and PS2 waves using all three components. The core of our method is the rotation of wave vectors from the Cartesian coordinate system established by Z-, R- and T-axes to a coordinate system established by the true PP-, PS1- and PS2-wave vector directions. Further, we propose a three-component superposition approach to obtain base wave vectors for the coordinate system transformation. Synthetic data testing results confirm that the performance of our wave separation method is stable under different noise levels. Application to field data from Southwest China reveals the potential of our proposed method.

Tunneling dynamics of double proton transfer in formic acid and benzoic acid dimers

NASA Astrophysics Data System (ADS)

Smedarchina, Zorka; Fernández-Ramos, Antonio; Siebrand, Willem

2005-04-01

Direct dynamics calculations based on instanton techniques are reported of tunneling splittings due to double proton transfer in formic and benzoic acid dimers. The results are used to assign the observed splittings to levels for which the authors of the high-resolution spectra could not provide a definitive assignment. In both cases the splitting is shown to be due mainly to the zero-point level rather than to the vibrationally or electronically excited level whose spectrum was investigated. This leads to zero-point splittings of 375MHz for (DCOOH)2 and 1107MHz for the benzoic acid dimer. Thus, contrary to earlier calculations, it is found that the splitting is considerably larger in the benzoic than in the formic acid dimer. The calculations are extended to solid benzoic acid where the asymmetry of the proton-transfer potential induced by the crystal can be overcome by suitable doping. This has allowed direct measurement of the interactions responsible for double proton transfer, which were found to be much larger than those in the isolated dimer. To account for this observation both static and dynamic effects of the crystal forces on the intradimer hydrogen bonds are included in the calculations. The same methodology, extended to higher temperatures, is used to calculate rate constants for HH, HD, and DD transfers in neat benzoic acid crystals. The results are in good agreement with reported experimental rate constants measured by NMR relaxometry and, if allowance is made for small structural changes induced by doping, with the transfer matrix elements observed in doped crystals. Hence the method used allows a unified description of tunneling splittings in the gas phase and in doped crystals as well as of transfer rates in neat crystals.

Core-Shell ZIF-8@ZIF-67-Derived CoP Nanoparticle-Embedded N-Doped Carbon Nanotube Hollow Polyhedron for Efficient Overall Water Splitting.

PubMed

Pan, Yuan; Sun, Kaian; Liu, Shoujie; Cao, Xing; Wu, Konglin; Cheong, Weng-Chon; Chen, Zheng; Wang, Yu; Li, Yang; Liu, Yunqi; Wang, Dingsheng; Peng, Qing; Chen, Chen; Li, Yadong

2018-02-21

The construction of highly active and stable non-noble-metal electrocatalysts for hydrogen and oxygen evolution reactions is a major challenge for overall water splitting. Herein, we report a novel hybrid nanostructure with CoP nanoparticles (NPs) embedded in a N-doped carbon nanotube hollow polyhedron (NCNHP) through a pyrolysis-oxidation-phosphidation strategy derived from core-shell ZIF-8@ZIF-67. Benefiting from the synergistic effects between highly active CoP NPs and NCNHP, the CoP/NCNHP hybrid exhibited outstanding bifunctional electrocatalytic performances. When the CoP/NCNHP was employed as both the anode and cathode for overall water splitting, a potential as low as 1.64 V was needed to achieve the current density of 10 mA·cm -2 , and it still exhibited superior activity after continuously working for 36 h with nearly negligible decay in potential. Density functional theory calculations indicated that the electron transfer from NCNHP to CoP could increase the electronic states of the Co d-orbital around the Fermi level, which could increase the binding strength with H and therefore improve the electrocatalytic performance. The strong stability is attributed to high oxidation resistance of the CoP surface protected by the NCNHP.

Dental occlusion in a split Amazon indigenous population: genetics prevails over environment.

PubMed

Normando, David; Faber, Jorge; Guerreiro, João Farias; Quintão, Cátia Cardoso Abdo

2011-01-01

Studies examining human and nonhuman primates have supported the hypothesis that the recent increase in the occurrence of misalignment of teeth and/or incorrect relation of dental arches, named dental malocclusion, is mainly attributed to the availability of a more processed diet and the reduced need for powerful masticatory action. For the first time on live human populations, genetic and tooth wear influences on occlusal variation were examined in a split indigenous population. The Arara-Iriri people are descendants of a single couple expelled from a larger village. In the resultant village, expansion occurred through the mating of close relatives, resulting in marked genetic cohesion with substantial genetic differences. Dental malocclusion, tooth wear and inbreeding coefficient were evaluated. The sample examined was composed of 176 individuals from both villages. Prevalence Ratio and descriptive differences in the outcomes frequency for each developmental stage of the dentition were considered. Statistical differences between the villages were examined using the chi-square test or Fisher's exact statistic. Tooth wear and the inbreeding coefficient (F) between the villages was tested with Mann-Whitney statistics. All the statistics were performed using two-tailed distribution at p≤0.05. The coefficient inbreeding (F) confirmed the frequent incestuous unions among the Arara-Iriri indigenous group. Despite the tooth wear similarities, we found a striking difference in occlusal patterns between the two Arara villages. In the original village, dental malocclusion was present in about one third of the population; whilst in the resultant village, the occurrence was almost doubled. Furthermore, the morphological characteristics of malocclusion were strongly different between the groups. Our findings downplay the widespread influence of tooth wear, a direct evidence of what an individual ate in the past, on occlusal variation of living human populations. They also suggest that genetics plays the most important role on dental malocclusion etiology. © 2011 Normando et al.

Lumber potential of 12-year-old Saligna eucalyptus trees in Hawaii

Treesearch

Roger G. Skolmen

1974-01-01

The sawtimber potential of 12-year-old Eucalyptus saligna Sm. trees grown in Maui, Hawaii, was studied by using simple field techniques. Lumber manufactured from the trees was predominantly of low grade, but had lower average density than wood from older trees, and therefore was more desirable. Logs end-split badly, and sawed with the usually...

Split Nitrogen Application Improves Wheat Baking Quality by Influencing Protein Composition Rather Than Concentration.

PubMed

Xue, Cheng; Auf'm Erley, Gunda Schulte; Rossmann, Anne; Schuster, Ramona; Koehler, Peter; Mühling, Karl-Hermann

2016-01-01

The use of late nitrogen (N) fertilization (N application at late growth stages of wheat, e.g., booting, heading or anthesis) to improve baking quality of wheat has been questioned. Although it increases protein concentration, the beneficial effect on baking quality (bread loaf volume) needs to be clearly understood. Two pot experiments were conducted aiming to evaluate whether late N is effective under controlled conditions and if these effects result from increased N rate or N splitting. Late N fertilizers were applied either as additional N or split from the basal N at late boot stage or heading in the form of nitrate-N or urea. Results showed that late N fertilization improved loaf volume of wheat flour by increasing grain protein concentration and altering its composition. Increasing N rate mainly enhanced grain protein quantitatively. However, N splitting changed grain protein composition by enhancing the percentages of gliadins and glutenins as well as certain high molecular weight glutenin subunits (HMW-GS), which led to an improved baking quality of wheat flour. The late N effects were greater when applied as nitrate-N than urea. The proportions of glutenin and x-type HMW-GS were more important than the overall protein concentration in determining baking quality. N splitting is more effective in improving wheat quality than the increase in the N rate by late N, which offers the potential to cut down N fertilization rates in wheat production systems.

Split Nitrogen Application Improves Wheat Baking Quality by Influencing Protein Composition Rather Than Concentration

PubMed Central

Xue, Cheng; auf’m Erley, Gunda Schulte; Rossmann, Anne; Schuster, Ramona; Koehler, Peter; Mühling, Karl-Hermann

2016-01-01

The use of late nitrogen (N) fertilization (N application at late growth stages of wheat, e.g., booting, heading or anthesis) to improve baking quality of wheat has been questioned. Although it increases protein concentration, the beneficial effect on baking quality (bread loaf volume) needs to be clearly understood. Two pot experiments were conducted aiming to evaluate whether late N is effective under controlled conditions and if these effects result from increased N rate or N splitting. Late N fertilizers were applied either as additional N or split from the basal N at late boot stage or heading in the form of nitrate-N or urea. Results showed that late N fertilization improved loaf volume of wheat flour by increasing grain protein concentration and altering its composition. Increasing N rate mainly enhanced grain protein quantitatively. However, N splitting changed grain protein composition by enhancing the percentages of gliadins and glutenins as well as certain high molecular weight glutenin subunits (HMW-GS), which led to an improved baking quality of wheat flour. The late N effects were greater when applied as nitrate-N than urea. The proportions of glutenin and x-type HMW-GS were more important than the overall protein concentration in determining baking quality. N splitting is more effective in improving wheat quality than the increase in the N rate by late N, which offers the potential to cut down N fertilization rates in wheat production systems. PMID:27313585

An Extension of the Split Window Technique for the Retrieval of Precipitable Water: Experimental Verification

DTIC Science & Technology

1988-09-23

DOWNGRADING SCHEDULE D~istribution Unlimited 4. PERFORMING ORGANIZATiON REPORT NUMVBER(S) 5. MONITORiG ORGANIZATION REPORT NUMBER(S) AFGL-TR-88-0237...Collocations were performed on launch sites of the cloud contamination, aerosol problems, collocation 1200 UT radiosondes on 25 Aug 1987. Statistics were...al (1987) and Thomason, 1987). In this imagery opaque clouds to this problem appear white, low clouds and fog appear bright red against a brown

Performance Optimization of Alternative Lower Global Warming Potential Refrigerants in Mini-Split Room Air Conditioners

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

Shen, Bo; Abdelaziz, Omar; Shrestha, Som S

Oak Ridge National laboratory (ORNL) recently conducted extensive laboratory, drop-in investigations for lower Global Warming Potential (GWP) refrigerants to replace R-22 and R-410A. ORNL studied propane, DR-3, ARM-20B, N-20B and R-444B as lower GWP refrigerant replacement for R-22 in a mini-split room air conditioner (RAC) originally designed for R-22; and, R-32, DR-55, ARM-71A, and L41-2, in a mini-split RAC designed for R-410A. We obtained laboratory testing results with very good energy balance and nominal measurement uncertainty. Drop-in studies are not enough to judge the overall performance of the alternative refrigerants since their thermodynamic and transport properties might favor different heatmore » exchanger configurations, e.g. cross-flow, counter flow, etc. This study compares optimized performances of individual refrigerants using a physics-based system model tools. The DOE/ORNL Heat Pump Design Model (HPDM) was used to model the mini-split RACs by inputting detailed heat exchangers geometries, compressor displacement and efficiencies as well as other relevant system components. The RAC models were calibrated against the lab data for each individual refrigerant. The calibrated models were then used to conduct a design optimization for the cooling performance by varying the compressor displacement to match the required capacity, and changing the number of circuits, refrigerant flow direction, tube diameters, air flow rates in the condenser and evaporator at 100% and 50% cooling capacities. This paper compares the optimized performance results for all alternative refrigerants and highlights best candidates for R-22 and R-410A replacement.« less

Implementation and value of using a split-plot reader design in a study of digital breast tomosynthesis in a breast cancer assessment clinic

NASA Astrophysics Data System (ADS)

Mall, Suneeta; Brennan, Patrick C.; Mello-Thoms, Claudia

2015-03-01

The rapid evolution in medical imaging has led to an increased number of recurrent trials, primarily to ensure that the efficacy of new imaging techniques is known. The cost associated with time and resources in conducting such trials is usually high. The recruitment of participants, in a medium to large reader study, is often very challenging as the demanding number of cases discourages involvement with the trial. We aim to evaluate the efficacy of Digital Breast Tomosynthesis (DBT) in a recall assessment clinic in Australia in a prospective multi-reader-multi-case (MRMC) trial. Conducting such a study with the more commonly used fully crossed MRMC study design would require more cases and more cases read per reader, which was not viable in our setting. With an aim to perform a cost effective yet statistically efficient clinical trial, we evaluated alternative study designs, particularly the alternative split-plot MRMC study design and compared and contrasted it with more commonly used fully crossed MRMC study design. Our results suggest that `split-plot', an alternative MRMC study design, could be very beneficial for medium to large clinical trials and the cost associated with conducting such trials can be greatly reduced without adversely effecting the variance of the study. We have also noted an inverse dependency between number of required readers and cases to achieve a target variance. This suggests that split-plot could also be very beneficial for studies that focus on cases that are hard to procure or readers that are hard to recruit. We believe that our results may be relevant to other researchers seeking to design a medium to large clinical trials.

Entropy Splitting for High Order Numerical Simulation of Compressible Turbulence

NASA Technical Reports Server (NTRS)

Sandham, N. D.; Yee, H. C.; Kwak, Dochan (Technical Monitor)

2000-01-01

A stable high order numerical scheme for direct numerical simulation (DNS) of shock-free compressible turbulence is presented. The method is applicable to general geometries. It contains no upwinding, artificial dissipation, or filtering. Instead the method relies on the stabilizing mechanisms of an appropriate conditioning of the governing equations and the use of compatible spatial difference operators for the interior points (interior scheme) as well as the boundary points (boundary scheme). An entropy splitting approach splits the inviscid flux derivatives into conservative and non-conservative portions. The spatial difference operators satisfy a summation by parts condition leading to a stable scheme (combined interior and boundary schemes) for the initial boundary value problem using a generalized energy estimate. A Laplacian formulation of the viscous and heat conduction terms on the right hand side of the Navier-Stokes equations is used to ensure that any tendency to odd-even decoupling associated with central schemes can be countered by the fluid viscosity. A special formulation of the continuity equation is used, based on similar arguments. The resulting methods are able to minimize spurious high frequency oscillation producing nonlinear instability associated with pure central schemes, especially for long time integration simulation such as DNS. For validation purposes, the methods are tested in a DNS of compressible turbulent plane channel flow at a friction Mach number of 0.1 where a very accurate turbulence data base exists. It is demonstrated that the methods are robust in terms of grid resolution, and in good agreement with incompressible channel data, as expected at this Mach number. Accurate turbulence statistics can be obtained with moderate grid sizes. Stability limits on the range of the splitting parameter are determined from numerical tests.

Corruption of accuracy and efficiency of Markov chain Monte Carlo simulation by inaccurate numerical implementation of conceptual hydrologic models

NASA Astrophysics Data System (ADS)

Schoups, G.; Vrugt, J. A.; Fenicia, F.; van de Giesen, N. C.

2010-10-01

Conceptual rainfall-runoff models have traditionally been applied without paying much attention to numerical errors induced by temporal integration of water balance dynamics. Reliance on first-order, explicit, fixed-step integration methods leads to computationally cheap simulation models that are easy to implement. Computational speed is especially desirable for estimating parameter and predictive uncertainty using Markov chain Monte Carlo (MCMC) methods. Confirming earlier work of Kavetski et al. (2003), we show here that the computational speed of first-order, explicit, fixed-step integration methods comes at a cost: for a case study with a spatially lumped conceptual rainfall-runoff model, it introduces artificial bimodality in the marginal posterior parameter distributions, which is not present in numerically accurate implementations of the same model. The resulting effects on MCMC simulation include (1) inconsistent estimates of posterior parameter and predictive distributions, (2) poor performance and slow convergence of the MCMC algorithm, and (3) unreliable convergence diagnosis using the Gelman-Rubin statistic. We studied several alternative numerical implementations to remedy these problems, including various adaptive-step finite difference schemes and an operator splitting method. Our results show that adaptive-step, second-order methods, based on either explicit finite differencing or operator splitting with analytical integration, provide the best alternative for accurate and efficient MCMC simulation. Fixed-step or adaptive-step implicit methods may also be used for increased accuracy, but they cannot match the efficiency of adaptive-step explicit finite differencing or operator splitting. Of the latter two, explicit finite differencing is more generally applicable and is preferred if the individual hydrologic flux laws cannot be integrated analytically, as the splitting method then loses its advantage.

Validation of 31 of the most commonly used immunohistochemical antibodies in cytology prepared using the Cellient(®) automated cell block system.

PubMed

Montgomery, Eric; Gao, Chen; de Luca, Julie; Bower, Jessie; Attwood, Kristropher; Ylagan, Lourdes

2014-12-01

The Cellient(®) cell block system has become available as an alternative, partially automated method to create cell blocks in cytology. We sought to show a validation method for immunohistochemical (IHC) staining on the Cellient cell block system (CCB) in comparison with the formalin fixed paraffin embedded traditional cell block (TCB). Immunohistochemical staining was performed using 31 antibodies on 38 patient samples for a total of 326 slides. Split samples were processed using both methods by following the Cellient(®) manufacturer's recommendations for the Cellient cell block (CCB) and the Histogel method for preparing the traditional cell block (TCB). Interpretation was performed by three pathologists and two cytotechnologists. Immunohistochemical stains were scored as: 0/1+ (negative) and 2/3+ (positive). Inter-rater agreement for each antibody was evaluated for CCB and TCB, as well as the intra-rater agreement between TCB and CCB between observers. Interobserver staining concordance for the TCB was obtained with statistical significance (P < 0.05) in 24 of 31 antibodies. Interobserver staining concordance for the CCB was obtained with statistical significance in 27 of 31 antibodies. Intra-observer staining concordance between TCB and CCB was obtained with statistical significance in 24 of 31 antibodies tested. In conclusions, immunohistochemical stains on cytologic specimens processed by the Cellient system are reliable and concordant with stains performed on the same split samples processed via a formalin fixed-paraffin embedded (FFPE) block. The Cellient system is a welcome adjunct to cytology work-flow by producing cell block material of sufficient quality to allow the use of routine IHC. © 2014 Wiley Periodicals, Inc.

Quantifying trends in disease impact to produce a consistent and reproducible definition of an emerging infectious disease.

PubMed

Funk, Sebastian; Bogich, Tiffany L; Jones, Kate E; Kilpatrick, A Marm; Daszak, Peter

2013-01-01

The proper allocation of public health resources for research and control requires quantification of both a disease's current burden and the trend in its impact. Infectious diseases that have been labeled as "emerging infectious diseases" (EIDs) have received heightened scientific and public attention and resources. However, the label 'emerging' is rarely backed by quantitative analysis and is often used subjectively. This can lead to over-allocation of resources to diseases that are incorrectly labelled "emerging," and insufficient allocation of resources to diseases for which evidence of an increasing or high sustained impact is strong. We suggest a simple quantitative approach, segmented regression, to characterize the trends and emergence of diseases. Segmented regression identifies one or more trends in a time series and determines the most statistically parsimonious split(s) (or joinpoints) in the time series. These joinpoints in the time series indicate time points when a change in trend occurred and may identify periods in which drivers of disease impact change. We illustrate the method by analyzing temporal patterns in incidence data for twelve diseases. This approach provides a way to classify a disease as currently emerging, re-emerging, receding, or stable based on temporal trends, as well as to pinpoint the time when the change in these trends happened. We argue that quantitative approaches to defining emergence based on the trend in impact of a disease can, with appropriate context, be used to prioritize resources for research and control. Implementing this more rigorous definition of an EID will require buy-in and enforcement from scientists, policy makers, peer reviewers and journal editors, but has the potential to improve resource allocation for global health.

Improving machine learning reproducibility in genetic association studies with proportional instance cross validation (PICV).

PubMed

Piette, Elizabeth R; Moore, Jason H

2018-01-01

Machine learning methods and conventions are increasingly employed for the analysis of large, complex biomedical data sets, including genome-wide association studies (GWAS). Reproducibility of machine learning analyses of GWAS can be hampered by biological and statistical factors, particularly so for the investigation of non-additive genetic interactions. Application of traditional cross validation to a GWAS data set may result in poor consistency between the training and testing data set splits due to an imbalance of the interaction genotypes relative to the data as a whole. We propose a new cross validation method, proportional instance cross validation (PICV), that preserves the original distribution of an independent variable when splitting the data set into training and testing partitions. We apply PICV to simulated GWAS data with epistatic interactions of varying minor allele frequencies and prevalences and compare performance to that of a traditional cross validation procedure in which individuals are randomly allocated to training and testing partitions. Sensitivity and positive predictive value are significantly improved across all tested scenarios for PICV compared to traditional cross validation. We also apply PICV to GWAS data from a study of primary open-angle glaucoma to investigate a previously-reported interaction, which fails to significantly replicate; PICV however improves the consistency of testing and training results. Application of traditional machine learning procedures to biomedical data may require modifications to better suit intrinsic characteristics of the data, such as the potential for highly imbalanced genotype distributions in the case of epistasis detection. The reproducibility of genetic interaction findings can be improved by considering this variable imbalance in cross validation implementation, such as with PICV. This approach may be extended to problems in other domains in which imbalanced variable distributions are a concern.

Dynamics of nonlinear Schrödinger breathers in a potential trap

NASA Astrophysics Data System (ADS)

Malomed, B. A.; Rosanov, N. N.; Fedorov, S. V.

2018-05-01

We consider the evolution of the 2-soliton (breather) of the nonlinear Schrödinger equation on a semi-infinite line with the zero boundary condition and a linear potential, which corresponds to the gravity field in the presence of a hard floor. This setting can be implemented in atomic Bose-Einstein condensates, and in a nonlinear planar waveguide in optics. In the absence of the gravity, repulsion of the breather from the floor leads to its splitting into constituent fundamental solitons, if the initial distance from the floor is smaller than a critical value; otherwise, the moving breather persists. In the presence of gravity, the breather always splits into a pair of "co-hopping" fundamental solitons, which may be frequency locked in the form of a quasi-breather, or unlocked, forming an incoherent pseudo-breather. Some essential results are obtained in an analytical form, in addition to the systematic numerical investigation.

Neutron–proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon–nucleus scattering data within an isospin dependent optical model

DOE PAGES

Li, Xiao -Hua; Guo, Wen -Jun; Li, Bao -An; ...

2015-04-01

The neutron–proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be m* n-p≡(m* n – m* p)/m = (0.41 ± 0.15)δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependencemore » of the nucleon isovector potential necessary for understanding novel structures and reactions of rare isotopes.« less

Direct Mapping of Band Positions in Doped and Undoped Hematite during Photoelectrochemical Water Splitting

DOE PAGES

Shavorskiy, Andrey; Ye, Xiaofei; Karslgolu, Osman; ...

2017-10-30

Photoelectrochemical water splitting is a promising pathway for the direct conversion of renewable solar energy to easy to store and use chemical energy. The performance of a photoelectrochemical device is determined in large part by the heterogeneous interface between the photoanode and the electrolyte, which we here characterize directly under operating conditions using interface-specific probes. Utilizing X-ray photoelectron spectroscopy as a noncontact probe of local electrical potentials, we demonstrate direct measurements of the band alignment at the semiconductor/electrolyte interface of an operating hematite/KOH photoelectrochemical cell as a function of solar illumination, applied potential, and doping. Here, we provide evidence formore » the absence of in-gap states in this system, which is contrary to previous measurements using indirect methods, and give a comprehensive description of shifts in the band positions and limiting processes during the photoelectrochemical reaction.« less

Nekton Interaction Monitoring System

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

2017-03-15

The software provides a real-time processing system for sonar to detect and track animals, and to extract water column biomass statistics in order to facilitate continuous monitoring of an underwater environment. The Nekton Interaction Monitoring System (NIMS) extracts and archives tracking and backscatter statistics data from a real-time stream of data from a sonar device. NIMS also sends real-time tracking messages over the network that can be used by other systems to generate other metrics or to trigger instruments such as an optical video camera. A web-based user interface provides remote monitoring and control. NIMS currently supports three popular sonarmore » devices: M3 multi-beam sonar (Kongsberg), EK60 split-beam echo-sounder (Simrad) and BlueView acoustic camera (Teledyne).« less

Effects of Simplifying Choice Tasks on Estimates of Taste Heterogeneity in Stated-Choice Surveys

PubMed Central

Johnson, F. Reed; Ozdemir, Semra; Phillips, Kathryn A

2011-01-01

Researchers usually employ orthogonal arrays or D-optimal designs with little or no attribute overlap in stated-choice surveys. The challenge is to balance statistical efficiency and respondent burden to minimize the overall error in the survey responses. This study examined whether simplifying the choice task, by using a design with more overlap, provides advantages over standard minimum-overlap methods. We administered two designs for eliciting HIV test preferences to split samples. Surveys were undertaken at four HIV testing locations in San Francisco, California. Personal characteristics had different effects on willingness to pay for the two treatments, and gains in statistical efficiency in the minimal-overlap version more than compensated for possible imprecision from increased measurement error. PMID:19880234

Si-H induced synthesis of Si/Cu2O nanowire arrays for photoelectrochemical water splitting

NASA Astrophysics Data System (ADS)

Zhang, Shaoyang; She, Guangwei; Li, Shengyang; Mu, Lixuan; Shi, Wensheng

2018-01-01

We report a facile and low-cost method to synthesize Si/Cu2O heterojunction nanowire arrays, without SiOx, at the Si/Cu2O interface. The reductive Si-H bonds on the surface of Si nanowires plays a key role in situ by reducing Cu(II) ions to Cu2O nanocubes and avoiding the SiOx interface layer. Different pH values would vary the electrochemical potential of reactions and as a result, different products would be formed. Utilized as a photoanode for water splitting, Si/Cu2O nanowire arrays exhibit good photoelectrochemical performance.

Research Update: Photoelectrochemical water splitting and photocatalytic hydrogen production using ferrites (MFe2O4) under visible light irradiation

NASA Astrophysics Data System (ADS)

Dillert, Ralf; Taffa, Dereje H.; Wark, Michael; Bredow, Thomas; Bahnemann, Detlef W.

2015-10-01

The utilization of solar light for the photoelectrochemical and photocatalytic production of molecular hydrogen from water is a scientific and technical challenge. Semiconductors with suitable properties to promote solar-driven water splitting are a desideratum. A hitherto rarely investigated group of semiconductors are ferrites with the empirical formula MFe2O4 and related compounds. This contribution summarizes the published results of the experimental investigations on the photoelectrochemical and photocatalytic properties of these compounds. It will be shown that the potential of this group of compounds in regard to the production of solar hydrogen has not been fully explored yet.

Conformational Characteristics of Poly(tetrafluoroethylene) (PTFE) Based Upon Ab Initio Electronic Structure Calculations on Model Molecules

NASA Technical Reports Server (NTRS)

Smith, Grant D.; Jaffe, R. L.; Yoon, D. Y.; Arnold, James O. (Technical Monitor)

1994-01-01

Conformational energy contours of perfluoroalkanes, determined from ab initio calculations, confirm the well-known spitting of trans states into two minima at plus or minus 17 degrees but also show that the gauche states split as well, with minima at plus or minus 124 degrees and plus or minus 84 in order to relieve steric crowding. The directions of such split distortions from the perfectly staggered states are strongly coupled for adjacent pairs of bonds in a manner identical to the intradyad pair for poly (isobutylene) chains. These conformational characteristics are fully represented by a six-state rotational isomeric state (RIS) model for PTFE comprised of t(+), t(-), g(sup +)+, g(sup +)-, g(sup -) + and g(sup -)-states, located at the split energy minima. The resultant 6 x 6 statistical weight matrix is described by first-order interaction parameters for the g+(+) (ca. 0.6 kcal/mol) and g+- (ca. 2.0 kcal/mol) states, and second order parameters for the g(sup +)+g(sup +)+ (ca 0.6 kcal/mol) and g(sup +)+g(sup -)+ (ca. 1.0 kcal/mol) states. This six-state RIS model, without adjustment of the geometric or energy parameters as determined from the ab initio calculations, predicts the unperturbed chain dimensions and the fraction of gauche bonds as a function of temperature for PTFE in good agreement with available experimental values.

Self-Replication of Localized Vegetation Patches in Scarce Environments

NASA Astrophysics Data System (ADS)

Bordeu, Ignacio; Clerc, Marcel G.; Couteron, Piere; Lefever, René; Tlidi, Mustapha

2016-09-01

Desertification due to climate change and increasing drought periods is a worldwide problem for both ecology and economy. Our ability to understand how vegetation manages to survive and propagate through arid and semiarid ecosystems may be useful in the development of future strategies to prevent desertification, preserve flora—and fauna within—or even make use of scarce resources soils. In this paper, we study a robust phenomena observed in semi-arid ecosystems, by which localized vegetation patches split in a process called self-replication. Localized patches of vegetation are visible in nature at various spatial scales. Even though they have been described in literature, their growth mechanisms remain largely unexplored. Here, we develop an innovative statistical analysis based on real field observations to show that patches may exhibit deformation and splitting. This growth mechanism is opposite to the desertification since it allows to repopulate territories devoid of vegetation. We investigate these aspects by characterizing quantitatively, with a simple mathematical model, a new class of instabilities that lead to the self-replication phenomenon observed.

Cavity Born-Oppenheimer Approximation for Correlated Electron-Nuclear-Photon Systems.

PubMed

Flick, Johannes; Appel, Heiko; Ruggenthaler, Michael; Rubio, Angel

2017-04-11

In this work, we illustrate the recently introduced concept of the cavity Born-Oppenheimer approximation [ Flick et al. PNAS 2017 , 10.1073/pnas.1615509114 ] for correlated electron-nuclear-photon problems in detail. We demonstrate how an expansion in terms of conditional electronic and photon-nuclear wave functions accurately describes eigenstates of strongly correlated light-matter systems. For a GaAs quantum ring model in resonance with a photon mode we highlight how the ground-state electronic potential-energy surface changes the usual harmonic potential of the free photon mode to a dressed mode with a double-well structure. This change is accompanied by a splitting of the electronic ground-state density. For a model where the photon mode is in resonance with a vibrational transition, we observe in the excited-state electronic potential-energy surface a splitting from a single minimum to a double minimum. Furthermore, for a time-dependent setup, we show how the dynamics in correlated light-matter systems can be understood in terms of population transfer between potential energy surfaces. This work at the interface of quantum chemistry and quantum optics paves the way for the full ab initio description of matter-photon systems.

A structure-preserving split finite element discretization of the split 1D linear shallow-water equations

NASA Astrophysics Data System (ADS)

Bauer, Werner; Behrens, Jörn

2017-04-01

We present a locally conservative, low-order finite element (FE) discretization of the covariant 1D linear shallow-water equations written in split form (cf. tet{[1]}). The introduction of additional differential forms (DF) that build pairs with the original ones permits a splitting of these equations into topological momentum and continuity equations and metric-dependent closure equations that apply the Hodge-star. Our novel discretization framework conserves this geometrical structure, in particular it provides for all DFs proper FE spaces such that the differential operators (here gradient and divergence) hold in strong form. The discrete topological equations simply follow by trivial projections onto piecewise constant FE spaces without need to partially integrate. The discrete Hodge-stars operators, representing the discretized metric equations, are realized by nontrivial Galerkin projections (GP). Here they follow by projections onto either a piecewise constant (GP0) or a piecewise linear (GP1) space. Our framework thus provides essentially three different schemes with significantly different behavior. The split scheme using twice GP1 is unstable and shares the same discrete dispersion relation and similar second-order convergence rates as the conventional P1-P1 FE scheme that approximates both velocity and height variables by piecewise linear spaces. The split scheme that applies both GP1 and GP0 is stable and shares the dispersion relation of the conventional P1-P0 FE scheme that approximates the velocity by a piecewise linear and the height by a piecewise constant space with corresponding second- and first-order convergence rates. Exhibiting for both velocity and height fields second-order convergence rates, we might consider the split GP1-GP0 scheme though as stable versions of the conventional P1-P1 FE scheme. For the split scheme applying twice GP0, we are not aware of a corresponding conventional formulation to compare with. Though exhibiting larger absolute error values, it shows similar convergence rates as the other split schemes, but does not provide a satisfactory approximation of the dispersion relation as short waves are propagated much to fast. Despite this, the finding of this new scheme illustrates the potential of our discretization framework as a toolbox to find and to study new FE schemes based on new combinations of FE spaces. [1] Bauer, W. [2016], A new hierarchically-structured n-dimensional covariant form of rotating equations of geophysical fluid dynamics, GEM - International Journal on Geomathematics, 7(1), 31-101.

The suppression of pulsar and gamma-ray burst annihilation lines by magnetic photon splitting

NASA Technical Reports Server (NTRS)

Baring, Matthew G.

1993-01-01

Neutron stars, relativistic and compact by nature, show great potential for the copious creation of electron-positron pairs in the magnetospheres; these rapidly cool, thermalize, and then annihilate. It is therefore expected that many neutron sources might display evidence of pair annihilation lines in the 400-500 keV range. It is shown that magnetic photon splitting, which operates effectively at these energies and in the enormous neutron star magnetic fields, can destroy an annihilation feature by absorbing line photons and reprocessing them to lower energies. In so doing, photon splitting creates a soft gamma-ray bump and a broad quasi-power-law contribution to the X-ray continuum, which is too flat to conflict with the observed X-ray paucity in gamma-ray bursts. The destruction of the line occurs in neutron stars with surface fields of 5 x 10 exp 12 G or maybe even less, depending on the size of the emission region.

Decoupling Hydrogen and Oxygen Production in Acidic Water Electrolysis Using a Polytriphenylamine-Based Battery Electrode.

PubMed

Ma, Yuanyuan; Dong, Xiaoli; Wang, Yonggang; Xia, Yongyao

2018-03-05

Hydrogen production through water splitting is considered a promising approach for solar energy harvesting. However, the variable and intermittent nature of solar energy and the co-production of H 2 and O 2 significantly reduce the flexibility of this approach, increasing the costs of its use in practical applications. Herein, using the reversible n-type doping/de-doping reaction of the solid-state polytriphenylamine-based battery electrode, we decouple the H 2 and O 2 production in acid water electrolysis. In this architecture, the H 2 and O 2 production occur at different times, which eliminates the issue of gas mixing and adapts to the variable and intermittent nature of solar energy, facilitating the conversion of solar energy to hydrogen (STH). Furthermore, for the first time, we demonstrate a membrane-free solar water splitting through commercial photovoltaics and the decoupled acid water electrolysis, which potentially paves the way for a new approach for solar water splitting. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Giant onsite electronic entropy enhances the performance of ceria for water splitting

DOE PAGES

Naghavi, S. Shahab; Emery, Antoine A.; Hansen, Heine A.; ...

2017-08-18

Previous studies have shown that a large solid-state entropy of reduction increases the thermodynamic efficiency of metal oxides, such as ceria, for two-step thermochemical water splitting cycles. In this context, the configurational entropy arising from oxygen off-stoichiometry in the oxide, has been the focus of most previous work. Here we report a different source of entropy, the onsite electronic configurational entropy, arising from coupling between orbital and spin angular momenta in lanthanide f orbitals. We find that onsite electronic configurational entropy is sizable in all lanthanides, and reaches a maximum value of ≈4.7 k B per oxygen vacancy for Cemore » 4+/Ce 3+ reduction. This unique and large positive entropy source in ceria explains its excellent performance for high-temperature catalytic redox reactions such as water splitting. Our calculations also show that terbium dioxide has a high electronic entropy and thus could also be a potential candidate for solar thermochemical reactions.« less

The hydrogen tunneling splitting in malonaldehyde: A full-dimensional time-independent quantum mechanical method

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

Wu, Feng; Ren, Yinghui; Bian, Wensheng, E-mail: bian@iccas.ac.cn

The accurate time-independent quantum dynamics calculations on the ground-state tunneling splitting of malonaldehyde in full dimensionality are reported for the first time. This is achieved with an efficient method developed by us. In our method, the basis functions are customized for the hydrogen transfer process which has the effect of greatly reducing the size of the final Hamiltonian matrix, and the Lanczos method and parallel strategy are used to further overcome the memory and central processing unit time bottlenecks. The obtained ground-state tunneling splitting of 24.5 cm{sup −1} is in excellent agreement with the benchmark value of 23.8 cm{sup −1}more » computed with the full-dimensional, multi-configurational time-dependent Hartree approach on the same potential energy surface, and we estimate that our reported value has an uncertainty of less than 0.5 cm{sup −1}. Moreover, the role of various vibrational modes strongly coupled to the hydrogen transfer process is revealed.« less

A state interaction spin-orbit coupling density matrix renormalization group method

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

Sayfutyarova, Elvira R.; Chan, Garnet Kin-Lic

We describe a state interaction spin-orbit (SISO) coupling method using density matrix renormalization group (DMRG) wavefunctions and the spin-orbit mean-field (SOMF) operator. We implement our DMRG-SISO scheme using a spin-adapted algorithm that computes transition density matrices between arbitrary matrix product states. To demonstrate the potential of the DMRG-SISO scheme we present accurate benchmark calculations for the zero-field splitting of the copper and gold atoms, comparing to earlier complete active space self-consistent-field and second-order complete active space perturbation theory results in the same basis. We also compute the effects of spin-orbit coupling on the spin-ladder of the iron-sulfur dimer complex [Fe{submore » 2}S{sub 2}(SCH{sub 3}){sub 4}]{sup 3−}, determining the splitting of the lowest quartet and sextet states. We find that the magnitude of the zero-field splitting for the higher quartet and sextet states approaches a significant fraction of the Heisenberg exchange parameter.« less

Application of photon Doppler velocimetry to direct impact Hopkinson pressure bars

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

Lea, Lewis J., E-mail: ll379@cam.ac.uk; Jardine, Andrew P.

2016-02-15

Direct impact Hopkinson pressure bar systems offer many potential advantages over split Hopkinson pressure bars, including access to higher strain rates, higher strains for equivalent striker velocity and system length, lower dispersion, and faster achievement of force equilibrium. Currently, these advantages are gained at the expense of all information about the striker impacted specimen face, preventing the experimental determination of force equilibrium, and requiring approximations to be made on the sample deformation history. In this paper, we discuss an experimental method and complementary data analysis for using photon Doppler velocimetry to measure surface velocities of the striker and output barsmore » in a direct impact bar experiment, allowing similar data to be recorded as in a split bar system. We discuss extracting velocity and force measurements, and the precision of measurements. Results obtained using the technique are compared to equivalent split bar tests, showing improved stress measurements for the lowest and highest strains in fully dense metals, and improvement for all strains in slow and non-equilibrating materials.« less

Split-mode ultrasonic transducer.

PubMed

Ostrovskii, Igor; Cremaldi, Lucien

2013-08-01

A split-mode ultrasonic transducer is investigated in both theory and experiment. This transducer is a two-dimensional structure of periodically poled domains in a ferroelectric wafer with free surfaces. The acoustic vibrations are excited by a radio frequency electric current applied along the length of the wafer, which allows the basal-plane surfaces to be free of metal coatings and thus ready for further biomedical applications. A specific physical property of this transducer consists of the multiple acousto-electric resonances, which occur due to an acoustic mode split when the acoustic half-wavelength is equal to the domain length. Possible applications include ultrasonic generation and detection at the micro-scale, intravascular sonification and visualization, ultrasound therapy of localized small areas such as the eye, biomedical applications for cell cultures, and traditional nondestructive testing including bones and tissues. A potential use of a non-metallized wafer is a therapeutic application with double action that is both ultrasound itself and an electric field over the wafer. The experimental measurements and theoretical calculations are in good agreement.

Modeling of beam customization devices in the pencil-beam splitting algorithm for heavy charged particle radiotherapy.

PubMed

Kanematsu, Nobuyuki

2011-03-07

A broad-beam-delivery system for radiotherapy with protons or ions often employs multiple collimators and a range-compensating filter, which offer complex and potentially useful beam customization. It is however difficult for conventional pencil-beam algorithms to deal with fine structures of these devices due to beam-size growth during transport. This study aims to avoid the difficulty with a novel computational model. The pencil beams are initially defined at the range-compensating filter with angular-acceptance correction for upstream collimation followed by stopping and scattering. They are individually transported with possible splitting near the aperture edge of a downstream collimator to form a sharp field edge. The dose distribution for a carbon-ion beam was calculated and compared with existing experimental data. The penumbra sizes of various collimator edges agreed between them to a submillimeter level. This beam-customization model will be used in the greater framework of the pencil-beam splitting algorithm for accurate and efficient patient dose calculation.

Generation and control of polarization-entangled photons from GaAs island quantum dots by an electric field.

PubMed

Ghali, Mohsen; Ohtani, Keita; Ohno, Yuzo; Ohno, Hideo

2012-02-07

Semiconductor quantum dots are potential sources for generating polarization-entangled photons efficiently. The main prerequisite for such generation based on biexciton-exciton cascaded emission is to control the exciton fine-structure splitting. Among various techniques investigated for this purpose, an electric field is a promising means to facilitate the integration into optoelectronic devices. Here we demonstrate the generation of polarization-entangled photons from single GaAs quantum dots by an electric field. In contrast to previous studies, which were limited to In(Ga)As quantum dots, GaAs island quantum dots formed by a thickness fluctuation were used because they exhibit a larger oscillator strength and emit light with a shorter wavelength. A forward voltage was applied to a Schottky diode to control the fine-structure splitting. We observed a decrease and suppression in the fine-structure splitting of the studied single quantum dot with the field, which enabled us to generate polarization-entangled photons with a high fidelity of 0.72 ± 0.05.

Experimental detection of a Majorana mode in the core of a magnetic vortex inside a topological insulator-superconductor Bi(2)Te(3)/NbSe(2) heterostructure.

PubMed

Xu, Jin-Peng; Wang, Mei-Xiao; Liu, Zhi Long; Ge, Jian-Feng; Yang, Xiaojun; Liu, Canhua; Xu, Zhu An; Guan, Dandan; Gao, Chun Lei; Qian, Dong; Liu, Ying; Wang, Qiang-Hua; Zhang, Fu-Chun; Xue, Qi-Kun; Jia, Jin-Feng

2015-01-09

Majorana fermions have been intensively studied in recent years for their importance to both fundamental science and potential applications in topological quantum computing. They are predicted to exist in a vortex core of superconducting topological insulators. However, it is extremely difficult to distinguish them experimentally from other quasiparticle states for the tiny energy difference between Majorana fermions and these states, which is beyond the energy resolution of most available techniques. Here, we circumvent the problem by systematically investigating the spatial profile of the Majorana mode and the bound quasiparticle states within a vortex in Bi(2)Te(3) films grown on a superconductor NbSe(2). While the zero bias peak in local conductance splits right off the vortex center in conventional superconductors, it splits off at a finite distance ∼20  nm away from the vortex center in Bi(2)Te(3). This unusual splitting behavior has never been observed before and could be possibly due to the Majorana fermion zero mode. While the Majorana mode is destroyed by the interaction between vortices, the zero bias peak splits as a conventional superconductor again. This work provides self-consistent evidences of Majorana fermions and also suggests a possible route to manipulating them.

Strongly Coupled Molybdenum Carbide on Carbon Sheets as a Bifunctional Electrocatalyst for Overall Water Splitting.

PubMed

Wang, Hao; Cao, Yingjie; Sun, Cheng; Zou, Guifu; Huang, Jianwen; Kuai, Xiaoxiao; Zhao, Jianqing; Gao, Lijun

2017-09-22

High-performance and affordable electrocatalysts from earth-abundant elements are desirably pursued for water splitting involving hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Here, a bifunctional electrocatalyst of highly crystalline Mo 2 C nanoparticles supported on carbon sheets (Mo 2 C/CS) was designed toward overall water splitting. Owing to the highly active catalytic nature of Mo 2 C nanoparticles, the high surface area of carbon sheets and efficient charge transfer in the strongly coupled composite, the designed catalysts show excellent bifunctional behavior with an onset potential of -60 mV for HER and an overpotential of 320 mV to achieve a current density of 10 mA cm -2 for OER in 1 m KOH while maintaining robust stability. Moreover, the electrolysis cell using the catalyst only requires a low cell voltage of 1.73 V to achieve a current density of 10 mA cm -2 and maintains the activity for more than 100 h when employing the Mo 2 C/CS catalyst as both anode and cathode electrodes. Such high performance makes Mo 2 C/CS a promising electrocatalyst for practical hydrogen production from water splitting. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantum Transport Properties in Two-Dimensional and Low Dimensional Systems

NASA Astrophysics Data System (ADS)

Fang, Hao

1991-02-01

The quantum transport properties in quasi two -dimensional and zero-dimensional systems have been studied at magnetic field of 0 - 8T and low temperatures down to 1.3K. In the (100) Si inversion layer, we investigated the effect of valley splitting on the value of the enhanced effective g factor by the tilted magnetic field measurement. The valley splitting is determined from the beat effect on samples with measurable valley splitting behavior due to misorientation effects. Experimental results illustrate that the effective g factor is enhanced by many body interactions and that the valley splitting has no obvious effect on the g-value. A simulation calculation with a Gaussian distribution of density of states has been carried out and the simulated results are in an excellent agreement with the experimental data. A new and very simple technique has been developed for fabricating two-dimensional periodic submicron structures with feature sizes down to about 300 A. The etching mask is made by coating the material surface with a monolayer of close-packed uniform latex particles. We have demonstrated the formation of a quasi zero-dimensional quantum dot array and performed capacitance measurements on GaAs/AlGaAs heterostructure samples with periodicities ranging from 3000 to 4000 A. A series of nearly equally spaced peaks in a curve of the derivative of capacitance with respect to gate voltage, which corresponds to the energy levels formed by the lateral electric confining potential, is observed. The energy spacings and effective dot widths estimated from a simple parabolic potential model are consistent with the experimental data. Novel magnetoresistance oscillations in a two -dimensional electron gas modulated by a two-dimensional triangular superlattice potential are observed in GaAs/AlGaAs heterostructures. The new oscillations appear at very low magnetic fields and the peak positions are directly determined by the magnetic field and the periodicity of the modulation structure. New oscillation results from the modulation-broadened Landau bandwidth and the induced density of states variation with magnetic field. Physical explanations and theoretical approaches for the commensurability problem in a two-dimensional triangular superlattice potential are presented. The differences in oscillation frequencies and phase factors for two kinds of samples correlate with structures differing in degree of depletion and the resulting geometry.

Full-Potential Modeling of Blade-Vortex Interactions. Degree awarded by George Washington Univ., Feb. 1987

NASA Technical Reports Server (NTRS)

Jones, Henry E.

1997-01-01

A study of the full-potential modeling of a blade-vortex interaction was made. A primary goal of this study was to investigate the effectiveness of the various methods of modeling the vortex. The model problem restricts the interaction to that of an infinite wing with an infinite line vortex moving parallel to its leading edge. This problem provides a convenient testing ground for the various methods of modeling the vortex while retaining the essential physics of the full three-dimensional interaction. A full-potential algorithm specifically tailored to solve the blade-vortex interaction (BVI) was developed to solve this problem. The basic algorithm was modified to include the effect of a vortex passing near the airfoil. Four different methods of modeling the vortex were used: (1) the angle-of-attack method, (2) the lifting-surface method, (3) the branch-cut method, and (4) the split-potential method. A side-by-side comparison of the four models was conducted. These comparisons included comparing generated velocity fields, a subcritical interaction, and a critical interaction. The subcritical and critical interactions are compared with experimentally generated results. The split-potential model was used to make a survey of some of the more critical parameters which affect the BVI.

Nickel-based anodic electrocatalysts for fuel cells and water splitting

NASA Astrophysics Data System (ADS)

Chen, Dayi

Our world is facing an energy crisis, so people are trying to harvest and utilize energy more efficiently. One of the promising ways to harvest energy is via solar water splitting to convert solar energy to chemical energy stored in hydrogen. Another of the options to utilize energy more efficiently is to use fuel cells as power sources instead of combustion engines. Catalysts are needed to reduce the energy barriers of the reactions happening at the electrode surfaces of the water-splitting cells and fuel cells. Nickel-based catalysts happen to be important nonprecious electrocatalysts for both of the anodic reactions in alkaline media. In alcohol fuel cells, nickel-based catalysts catalyze alcohol oxidation. In water splitting cells, they catalyze water oxidation, i.e., oxygen evolution. The two reactions occur in a similar potential range when catalyzed by nickel-based catalysts. Higher output current density, lower oxidation potential, and complete substrate oxidation are preferred for the anode in the applications. In this dissertation, the catalytic properties of nickel-based electrocatalysts in alkaline medium for fuel oxidation and oxygen evolution are explored. By changing the nickel precursor solubility, nickel complex nanoparticles with tunable sizes on electrode surfaces were synthesized. Higher methanol oxidation current density is achieved with smaller nickel complex nanoparticles. DNA aggregates were used as a polymer scaffold to load nickel ion centers and thus can oxidize methanol completely at a potential about 0.1 V lower than simple nickel electrodes, and the methanol oxidation pathway is changed. Nickel-based catalysts also have electrocatalytic activity towards a wide range of substrates. Experiments show that methanol, ethanol, glycerol and glucose can be deeply oxidized and carbon-carbon bonds can be broken during the oxidation. However, when comparing methanol oxidation reaction to oxygen evolution reaction catalyzed by current nickel-based catalysts, methanol oxidation suffers from high overpotential and catalyst poisoning by high concentration of substrates, so current nickel-based catalysts are more suitable to be used as oxygen evolution catalysts. A photoanode design that applies nickel oxides to a semiconductor that is incorporated with surface-plasmonic metal electrodes to do solar water oxidation with visible light is proposed.

In Vivo Imaging of Human Cone Photoreceptor Inner Segments

PubMed Central

Scoles, Drew; Sulai, Yusufu N.; Langlo, Christopher S.; Fishman, Gerald A.; Curcio, Christine A.; Carroll, Joseph; Dubra, Alfredo

2014-01-01

Purpose. An often overlooked prerequisite to cone photoreceptor gene therapy development is residual photoreceptor structure that can be rescued. While advances in adaptive optics (AO) retinal imaging have recently enabled direct visualization of individual cone and rod photoreceptors in the living human retina, these techniques largely detect strongly directionally-backscattered (waveguided) light from normal intact photoreceptors. This represents a major limitation in using existing AO imaging to quantify structure of remnant cones in degenerating retina. Methods. Photoreceptor inner segment structure was assessed with a novel AO scanning light ophthalmoscopy (AOSLO) differential phase technique, that we termed nonconfocal split-detector, in two healthy subjects and four subjects with achromatopsia. Ex vivo preparations of five healthy donor eyes were analyzed for comparison of inner segment diameter to that measured in vivo with split-detector AOSLO. Results. Nonconfocal split-detector AOSLO reveals the photoreceptor inner segment with or without the presence of a waveguiding outer segment. The diameter of inner segments measured in vivo is in good agreement with histology. A substantial number of foveal and parafoveal cone photoreceptors with apparently intact inner segments were identified in patients with the inherited disease achromatopsia. Conclusions. The application of nonconfocal split-detector to emerging human gene therapy trials will improve the potential of therapeutic success, by identifying patients with sufficient retained photoreceptor structure to benefit the most from intervention. Additionally, split-detector imaging may be useful for studies of other retinal degenerations such as AMD, retinitis pigmentosa, and choroideremia where the outer segment is lost before the remainder of the photoreceptor cell. PMID:24906859

Sleep inertia during a simulated 6-h on/6-h off fixed split duty schedule.

PubMed

Hilditch, Cassie J; Short, Michelle; Van Dongen, Hans P A; Centofanti, Stephanie A; Dorrian, Jillian; Kohler, Mark; Banks, Siobhan

Sleep inertia is a safety concern for shift workers returning to work soon after waking up. Split duty schedules offer an alternative to longer shift periods, but introduce additional wake-ups and may therefore increase risk of sleep inertia. This study investigated sleep inertia across a split duty schedule. Sixteen participants (age range 21-36 years; 10 females) participated in a 9-day laboratory study with two baseline nights (10 h time in bed, [TIB]), four 24-h periods of a 6-h on/6-h off split duty schedule (5-h TIB in off period; 10-h TIB per 24 h) and two recovery nights. Two complementary rosters were evaluated, with the timing of sleep and wake alternating between the two rosters (2 am/2 pm wake-up roster versus 8 am/8 pm wake-up roster). At 2, 17, 32 and 47 min after scheduled awakening, participants completed an 8-min inertia test bout, which included a 3-min psychomotor vigilance test (PVT-B), a 3-min Digit-Symbol Substitution Task (DSST), the Karolinska Sleepiness Scale (KSS), and the Samn-Perelli Fatigue Scale (SP-Fatigue). Further testing occurred every 2 h during scheduled wakefulness. Performance was consistently degraded and subjective sleepiness/fatigue was consistently increased during the inertia testing period as compared to other testing times. Morning wake-ups (2 am and 8 am) were associated with higher levels of sleep inertia than later wake-ups (2 pm and 8 pm). These results suggest that split duty workers should recognise the potential for sleep inertia after waking, especially during the morning hours.

NMR in an electric field: A bulk probe of the hidden spin and orbital polarizations

NASA Astrophysics Data System (ADS)

Ramírez-Ruiz, Jorge; Boutin, Samuel; Garate, Ion

2017-12-01

Recent theoretical work has established the presence of hidden spin and orbital textures in nonmagnetic materials with inversion symmetry. Here, we propose that these textures can be detected by nuclear magnetic resonance (NMR) measurements carried out in the presence of an electric field. In crystals with hidden polarizations, a uniform electric field produces a staggered magnetic field that points to opposite directions at atomic sites related by spatial inversion. As a result, the NMR resonance peak corresponding to inversion partner nuclei is split into two peaks. The magnitude of the splitting is proportional to the electric field and depends on the orientation of the electric field with respect to the crystallographic axes and the external magnetic field. As a case study, we present a theory of electric-field-induced splitting of NMR peaks for 77Se,125Te, and 209Bi in Bi2Se3 and Bi2Te3 . In conducting samples with current densities of ≃106A/cm 2 , the splitting for Bi can reach 100 kHz , which is comparable to or larger than the intrinsic width of the NMR lines. In order to observe the effect experimentally, the peak splitting must also exceed the linewidth produced by the Oersted field. In Bi2Se3 , this requires narrow wires of radius ≲1 μ m . We also discuss other potentially more promising candidate materials, such as SrRuO3 and BaIr2Ge2 , whose crystal symmetry enables strategies to suppress the linewidth produced by the Oersted field.

Small Payload Integration and Testing Project Development

NASA Technical Reports Server (NTRS)

Sorenson, Tait R.

2014-01-01

The National Aeronautics and Space Administration's (NASA) Kennedy Space Center (KSC) has mainly focused on large payloads for space flight beginning with the Apollo program to the assembly and resupply of the International Space Station using the Space Shuttle. NASA KSC is currently working on contracting manned Low Earth Orbit (LEO) to commercial providers, developing Space Launch System, the Orion program, deep space manned programs which could reach Mars, and providing technical expertise for the Launch Services Program for science mission payloads/satellites. KSC has always supported secondary payloads and smaller satellites as the launch provider; however, they are beginning to take a more active role in integrating and testing secondary payloads into future flight opportunities. A new line of business, the Small Payload Integration and Testing Services (SPLITS), has been established to provide a one stop shop that can integrate and test payloads. SPLITS will assist high schools, universities, companies and consortiums interested in testing or launching small payloads. The goal of SPLITS is to simplify and facilitate access to KSC's expertise and capabilities for small payloads integration and testing and to help grow the space industry. An effort exists at Kennedy Space Center to improve the external KSC website. External services has partnered with SPLITS as a content test bed for attracting prospective customers. SPLITS is an emerging effort that coincides with the relaunch of the website and has a goal of attracting external partnerships. This website will be a "front door" access point for all potential partners as it will contain an overview of KSC's services, expertise and includes the pertinent contact information.

Resonance dynamical intermolecular interaction in the crystals of pure and binary mixture n-paraffins

NASA Astrophysics Data System (ADS)

Puchkovska, G. O.; Danchuk, V. D.; Makarenko, S. P.; Kravchuk, A. P.; Kotelnikova, E. N.; Filatov, S. K.

2004-12-01

In the present paper, we report temperature dependent FTIR spectra studies of Davydov splitting value for CH 2 rocking vibrations of pure crystalline n-paraffins C nH 2 n+2 ( n is the number of carbon atoms) and some isomorphically substituted binary mixtures of n-paraffins C 22H 46:C 24H 50. Temperature dependencies of Davydov splitting value have been shown to be characterized by the amount of irregularities (sharp decreasing), which corresponds to the phase transitions into the high-temperature (hexagonal) state for pure n-paraffins or different rotator crystalline states for the mixtures. Statistic and dynamic models have been proposed, which provides an adequate description of the observed effect. In the framework of these models, two different mechanisms are responsible for the temperature behavior of the vibrational mode splitting value. Besides the thermal expansion of crystals at heating, the quenching of vibrational excitons on the orientational defects of different nature takes place, accompanied with the breakage of the crystal lattice translational symmetry. The creation of such defects is resulted from the excitation of librational and rotational molecular degrees of freedom at the crystal polymorphic transitions into different rotary crystalline states. The manifestation of the resonance dynamical intermolecular interaction in the spectra of intramolecular vibrations in these crystals has been theoretically analyzed in terms of stochastic equations, taking into consideration the above mentioned phase transition. We have obtained the explicit expression for the theoretically predicted dependence of Davydov splitting value on temperature. The absorption bands, corresponding to Davydov splitting components, have been shown to approach rapidly each other at the transition to the high-temperature (hexagonal) phase. Computer simulation of such dependence has been performed for some aliphatic compounds. Good agreement between the experimental and computer simulation results has been obtained. The theoretical approach developed in the present paper for the resonance dynamical intermolecular interaction near such transitions from the three-dimensional to one-dimensional phase of crystalline n-paraffins has a general character and can be applied to the description of some specific features observed in the vibrational spectra of rotary crystals.

Preparation of laser micropore porcine acellular dermal matrix for skin graft: an experimental study.

PubMed

Chai, Jia-Ke; Liang, Li-Ming; Yang, Hong-Ming; Feng, Rui; Yin, Hui-Nan; Li, Feng-Yu; Sheng, Zhi-Yong

2007-09-01

In our previous study, we used composite grafts consisting of meshed porcine acellular dermal matrix (PADM) and thin split-thickness autologous epidermis to cover full thickness burn wounds in clinical practice. However, a certain degree of contraction might occur because the distribution of dermal matrix was not uniform in burn wound. In this study, we prepare a composite skin graft consisting of PADM with the aid of laser to improve the quality of healing of burn wound. PADM was prepared by the trypsin/Triton X-100 method. Micropores were produced on the PADM with a laser punch. The distance between micropores varied from 0.8, 1.0, 1.2 to 1.5mm. Full thickness defect wounds were created on the back of 144 SD rats. The rats were randomly divided into six groups: micropore groups I-IV in which the wound were grafted with PADM with micropores, in four different distances, respectively and split-thickness autograft; mesh group rats received meshed PADM graft and split-thickness autograft; control group received simple split-thickness autografting. The status of wound healing was histologically observed at regular time points after surgery. The wound healing rate and contraction rate were calculated. The wound healing rate in micropore groups I and II was not statistically different from that in control group, but was significantly higher than that in mesh group 6 weeks after grafting. The wound healing rate in micropore groups III and IV was lower than that in mesh and control groups 4 and 6 weeks after grafting. The wound contraction rate in micropore groups I and II was remarkably lower than that in control group 4 and 6 weeks after surgery and it was significantly much lower than that in mesh group 6 weeks after surgery. Histological examination revealed good epithelization, regularly arranged collagenous fibers and integral structure of basement membrane. Laser micropore PADM (0.8 or 1.0mm in distance) grafting in combination with split-thickness autografting can improve wound healing. The PADM with laser micropores in 1.0mm distance is the better choice.

Metagenomics workflow analysis of endophytic bacteria from oil palm fruits

NASA Astrophysics Data System (ADS)

Tanjung, Z. A.; Aditama, R.; Sudania, W. M.; Utomo, C.; Liwang, T.

2017-05-01

Next-Generation Sequencing (NGS) has become a powerful sequencing tool for microbial study especially to lead the establishment of the field area of metagenomics. This study described a workflow to analyze metagenomics data of a Sequence Read Archive (SRA) file under accession ERP004286 deposited by University of Sao Paulo. It was a direct sequencing data generated by 454 pyrosequencing platform originated from oil palm fruits endophytic bacteria which were cultured using oil-palm enriched medium. This workflow used SortMeRNA to split ribosomal reads sequence, Newbler (GS Assembler and GS Mapper) to assemble and map reads into genome reference, BLAST package to identify and annotate contigs sequence, and QualiMap for statistical analysis. Eight bacterial species were identified in this study. Enterobacter cloacae was the most abundant species followed by Citrobacter koseri, Seratia marcescens, Latococcus lactis subsp. lactis, Klebsiella pneumoniae, Citrobacter amalonaticus, Achromobacter xylosoxidans, and Pseudomonas sp. respectively. All of these species have been reported as endophyte bacteria in various plant species and each has potential as plant growth promoting bacteria or another application in agricultural industries.

DNA barcoding and regional diversity of understudied Micropeplinae (Coleoptera: Staphylinidae) in Southwest China: phylogenetic implications and a new Micropeplus from Mount Emei.

PubMed

Grebennikov, Vasily V; Smetana, Aleš

2015-02-18

Extensive litter sampling at eight forested localities in Yunnan and Sichuan detected 381 specimens of Micropeplinae rove beetles. DNA barcoding data from 85 representative specimens were analysed to delimit species and infer their relationships. Statistical methods were implemented to assess regional species diversity of understudied Micropeplinae. The total number of sampled Micropeplinae species varied between 14 and 17, depending on a splitting versus lumping approach for allopatric populations. A single Micropeplinae species was sampled in six of eight studied localities, three species were found on Mount Gongga, while ten species were discovered on hyperdiverse Mount Emei in Sichuan. All Micropeplinae specimens from our samples belong either to the genus Cerapeplus, or to three other inclusive groups temporarily retained inside Micropeplus sensu lato. Each of the three groups potentially represents a separate genus: tesserula group, sculptus group and Micropeplus sensu stricto. A new species Micropeplus jason sp. n. from Mount Emei in Sichuan is described. Numerous illustrations introduce regional fauna and clarify the discussed morphological characters.

Numerical simulation of turbulent stratified flame propagation in a closed vessel

NASA Astrophysics Data System (ADS)

Gruselle, Catherine; Lartigue, Ghislain; Pepiot, Perrine; Moureau, Vincent; D'Angelo, Yves

2012-11-01

Reducing pollutants emissions while keeping a high combustion efficiency and a low fuel consumption is an important challenge for both gas turbine (GT) and internal combustion engines (ICE). To fulfill these new constraints, stratified combustion may constitute an efficient strategy. A tabulated chemistry approach based on FPI combined to a low-Mach number method is applied in the analysis of a turbulent propane-air flame with equivalence ratio (ER) stratification, which has been studied experimentally by Balusamy [S. Balusamy, Ph.D Thesis, INSA-Rouen (2010)]. Flame topology, along with flame velocity statistics, are well reproduced in the simulation, even if time-history effects are not accounted for in the tabulated approach. However, these effects may become significant when exhaust gas recirculation (EGR) is introduced. To better quantify them, both ER and EGR-stratified two-dimensional flames are simulated using finite-rate chemistry and a semi-detailed mechanism for propane oxidation. The numerical implementation is first investigated in terms of efficiency and accuracy, with a focus on splitting errors. The resulting flames are then analyzed to investigate potential extensions of the FPI technique to EGR stratification.

Euclidean distance can identify the mannitol level that produces the most remarkable integral effect on sugarcane micropropagation in temporary immersion bioreactors.

PubMed

Gómez, Daviel; Hernández, L Ázaro; Yabor, Lourdes; Beemster, Gerrit T S; Tebbe, Christoph C; Papenbrock, Jutta; Lorenzo, José Carlos

2018-03-15

Plant scientists usually record several indicators in their abiotic factor experiments. The common statistical management involves univariate analyses. Such analyses generally create a split picture of the effects of experimental treatments since each indicator is addressed independently. The Euclidean distance combined with the information of the control treatment could have potential as an integrating indicator. The Euclidean distance has demonstrated its usefulness in many scientific fields but, as far as we know, it has not yet been employed for plant experimental analyses. To exemplify the use of the Euclidean distance in this field, we performed an experiment focused on the effects of mannitol on sugarcane micropropagation in temporary immersion bioreactors. Five mannitol concentrations were compared: 0, 50, 100, 150 and 200 mM. As dependent variables we recorded shoot multiplication rate, fresh weight, and levels of aldehydes, chlorophylls, carotenoids and phenolics. The statistical protocol which we then carried out integrated all dependent variables to easily identify the mannitol concentration that produced the most remarkable integral effect. Results provided by the Euclidean distance demonstrate a gradually increasing distance from the control in function of increasing mannitol concentrations. 200 mM mannitol caused the most significant alteration of sugarcane biochemistry and physiology under the experimental conditions described here. This treatment showed the longest statistically significant Euclidean distance to the control treatment (2.38). In contrast, 50 and 100 mM mannitol showed the lowest Euclidean distances (0.61 and 0.84, respectively) and thus poor integrated effects of mannitol. The analysis shown here indicates that the use of the Euclidean distance can contribute to establishing a more integrated evaluation of the contrasting mannitol treatments.

Splitting the mind within the individual, nation and economy: reflections on the struggle for integration in post-war Germany.

PubMed

Plänkers, Tomas

2015-02-01

With respect to theorisations of psychical splitting, this paper explores the psychical mechanisms that underlie different forms of social splitting. The paper first outlines Freud's and Kleins different theorisations of the psychical mechanisms of splitting, where the good is split from the bad, the inside split from the outside, and the painful disavowed. I then consider the psychical mechanisms of splitting that underlie ideological supports of certain social systems, specifically that of National Socialist Germany, East Germany during the Cold War period, and neoliberal capitalism. Here, I consider ideological splits between good and evil, the relation between external and internal splits, the relation between geographical, social and internal splitting, as well as splitting as disavowal of the other. Copyright © 2015 Institute of Psychoanalysis.

Potential Environmental Justice (EJ) areas in Region 2 based on 2000 Census [EPA.EJAREAS_2000

EPA Pesticide Factsheets

Potential Environmental Justice (EJ) areas in Region 2 . This dataset was derived from 2000 census data and based on the criteria setforth in the Region 2 Interim Environmental Justice Policy. The two criteria for Region 2's EJ demographic analysis are percent poverty and percent minority. The percent minority and percent poverty numbers for each blockgroup are compared to the benchmark value for the state. Census blockgroups with percent poverty or percent minority higher than the state threshold are considered potential EJ areas. The cutoffs for each state were derived by using the statistical method - cluster analysis.Cluster analysis was chosen as the most objective way of evaluating the demographic data and determining cutoff values for minority and low income. With cluster analysis, data are divided into two distinct groups (e.g., minority and non-minority, and low income and non-low income). Cluster analysis examines natural breaks of the data. Separate analyses were conducted for minority and low income, respectively, for each State. All census block groups within a State were ranked in descending order according to the demographic factor under evaluation. This resulted in a ranking for percent minority by block group and a separate ranking for percent low income by block group. An iterative process was employed where the data were (1) split into two groups; (2) the means for each of the two groups were calculated; (3) the difference between the

Water Splitting with Series-Connected Polymer Solar Cells.

PubMed

Esiner, Serkan; van Eersel, Harm; van Pruissen, Gijs W P; Turbiez, Mathieu; Wienk, Martijn M; Janssen, René A J

2016-10-12

We investigate light-driven electrochemical water splitting with series-connected polymer solar cells using a combined experimental and modeling approach. The expected maximum solar-to-hydrogen conversion efficiency (η STH ) for light-driven water splitting is modeled for two, three, and four series-connected polymer solar cells. In the modeling, we assume an electrochemical water splitting potential of 1.50 V and a polymer solar cell for which the external quantum efficiency and fill factor are both 0.65. The minimum photon energy loss (E loss ), defined as the energy difference between the optical band gap (E g ) and the open-circuit voltage (V oc ), is set to 0.8 eV, which we consider a realistic value for polymer solar cells. Within these approximations, two series-connected single junction cells with E g = 1.73 eV or three series-connected cells with E g = 1.44 eV are both expected to give an η STH of 6.9%. For four series-connected cells, the maximum η STH is slightly less at 6.2% at an optimal E g = 1.33 eV. Water splitting was performed with series-connected polymer solar cells using polymers with different band gaps. PTPTIBDT-OD (E g = 1.89 eV), PTB7-Th (E g = 1.56 eV), and PDPP5T-2 (E g = 1.44 eV) were blended with [70]PCBM as absorber layer for two, three, and four series-connected configurations, respectively, and provide η STH values of 4.1, 6.1, and 4.9% when using a retroreflective foil on top of the cell to enhance light absorption. The reasons for deviations with experiments are analyzed and found to be due to differences in E g and E loss . Light-driven electrochemical water splitting was also modeled for multijunction polymer solar cells with vertically stacked photoactive layers. Under identical assumptions, an η STH of 10.0% is predicted for multijunction cells.

Flow splitting in numerical simulations of oceanic dense-water outflows

NASA Astrophysics Data System (ADS)

Marques, Gustavo M.; Wells, Mathew G.; Padman, Laurie; Özgökmen, Tamay M.

2017-05-01

Flow splitting occurs when part of a gravity current becomes neutrally buoyant and separates from the bottom-trapped plume as an interflow. This phenomenon has been previously observed in laboratory experiments, small-scale water bodies (e.g., lakes) and numerical studies of small-scale systems. Here, the potential for flow splitting in oceanic gravity currents is investigated using high-resolution (Δx = Δz = 5 m) two-dimensional numerical simulations of gravity flows into linearly stratified environments. The model is configured to solve the non-hydrostatic Boussinesq equations without rotation. A set of experiments is conducted by varying the initial buoyancy number B0 =Q0N3 /g‧2 (where Q0 is the volume flux of the dense water flow per unit width, N is the ambient stratification and g‧ is the reduced gravity), the bottom slope (α) and the turbulent Prandtl number (Pr). Regardless of α or Pr, when B0 ≤ 0.002 the outflow always reaches the deep ocean forming an underflow. Similarly, when B0 ≥ 0.13 the outflow always equilibrates at intermediate depths, forming an interflow. However, when B0 ∼ 0.016, flow splitting always occurs when Pr ≥ 10, while interflows always occur for Pr = 1. An important characteristic of simulations that result in flow splitting is the development of Holmboe-like interfacial instabilities and flow transition from a supercritical condition, where the Froude number (Fr) is greater than one, to a slower and more uniform subcritical condition (Fr < 1). This transition is associated with an internal hydraulic jump and consequent mixing enhancement. Although our experiments do not take into account three-dimensionality and rotation, which are likely to influence mixing and the transition between flow regimes, a comparison between our results and oceanic observations suggests that flow splitting may occur in dense-water outflows with weak ambient stratification, such as Antarctic outflows.

Relationships between airborne pollen grains, wind direction and land cover using GIS and circular statistics.

PubMed

Maya-Manzano, J M; Sadyś, M; Tormo-Molina, R; Fernández-Rodríguez, S; Oteros, J; Silva-Palacios, I; Gonzalo-Garijo, A

2017-04-15

Airborne bio-aerosol content (mainly pollen and spores) depends on the surrounding vegetation and weather conditions, particularly wind direction. In order to understand this issue, maps of the main land cover in influence areas of 10km in radius surrounding pollen traps were created. Atmospheric content of the most abundant 14 pollen types was analysed in relation to the predominant wind directions measured in three localities of SW of Iberian Peninsula, from March 2011 to March 2014. Three Hirst type traps were used for aerobiological monitoring. The surface area for each land cover category was calculated and wind direction analysis was approached by using circular statistics. This method could be helpful for estimating the potential risk of exposure to various pollen types. Thus, the main land cover was different for each monitoring location, being irrigated crops, pastures and hardwood forests the main categories among 11 types described. Comparison of the pollen content with the predominant winds and land cover shows that the atmospheric pollen concentration is related to some source areas identified in the inventory. The study found that some pollen types (e.g. Plantago, Fraxinus-Phillyrea, Alnus) come from local sources but other pollen types (e.g. Quercus) are mostly coming from longer distances. As main conclusions, airborne particle concentrations can be effectively split by addressing wind with circular statistics. By combining circular statistics and GIS method with aerobiological data, we have created a useful tool for understanding pollen origin. Some pollen loads can be explained by immediate surrounding landscape and observed wind patterns for most of the time. However, other factors like medium or long-distance transport or even pollen trap location within a city, may occasionally affect the pollen load recorded using an air sampler. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparative evaluation of stress levels before, during, and after periodontal surgical procedures with and without nitrous oxide-oxygen inhalation sedation.

PubMed

Sandhu, Gurkirat; Khinda, Paramjit Kaur; Gill, Amarjit Singh; Singh Khinda, Vineet Inder; Baghi, Kamal; Chahal, Gurparkash Singh

2017-01-01

Periodontal surgical procedures produce varying degree of stress in all patients. Nitrous oxide-oxygen inhalation sedation is very effective for adult patients with mild-to-moderate anxiety due to dental procedures and needle phobia. The present study was designed to perform periodontal surgical procedures under nitrous oxide-oxygen inhalation sedation and assess whether this technique actually reduces stress physiologically, in comparison to local anesthesia alone (LA) during lengthy periodontal surgical procedures. This was a randomized, split-mouth, cross-over study. A total of 16 patients were selected for this randomized, split-mouth, cross-over study. One surgical session (SS) was performed under local anesthesia aided by nitrous oxide-oxygen inhalation sedation, and the other SS was performed on the contralateral quadrant under LA. For each session, blood samples to measure and evaluate serum cortisol levels were obtained, and vital parameters including blood pressure, heart rate, respiratory rate, and arterial blood oxygen saturation were monitored before, during, and after periodontal surgical procedures. Paired t -test and repeated measure ANOVA. The findings of the present study revealed a statistically significant decrease in serum cortisol levels, blood pressure and pulse rate and a statistically significant increase in respiratory rate and arterial blood oxygen saturation during periodontal surgical procedures under nitrous oxide inhalation sedation. Nitrous oxide-oxygen inhalation sedation for periodontal surgical procedures is capable of reducing stress physiologically, in comparison to LA during lengthy periodontal surgical procedures.

Randomized, controlled trial split-faced study of 595-nm pulsed dye laser in the treatment of acne vulgaris and acne erythema in adolescents and early adulthood.

PubMed

Lekwuttikarn, Ramrada; Tempark, Therdpong; Chatproedprai, Susheera; Wananukul, Siriwan

2017-08-01

The high prevalence of acne vulgaris in teenagers has increased comorbidities. Lasers offer alternative options for acne treatment because they have rapid action, low systemic adverse effects, and do not require everyday treatment. To study the efficacy and patients' satisfaction of 595-nm pulse dye laser (PDL) treatment of acne vulgaris and acne erythema in adolescents and early adulthood, we designed a blocked-randomized, split-faced 595-nm PDL (fluence 8 J/cm 3 pulse duration 10 ms, spot size 7 mm, 2 session every 2 weeks) study in patients with mild to moderate acne by comparing the laser-treated and non-treated side. The acne lesion counts, acne erythema grading, and acne severity grading were evaluated at baseline and 2, 4, and 8 weeks. Thirty patients were recruited. The results showed no statistically significant difference except the papule count at week 4 which was -1.828 on the treated side and 0.103 on the non-treated side of the face, P-value 0.0018. There was no statistically significant difference of acne severity grading and acne erythema grading between both sides of the face. The mean scores of patients' satisfaction on the laser-treated side were 75, 81, and 81%, respectively. The PDL treatment in this study reveals no significant improvement in acne therapy; however, the patients were satisfied with this laser treatment. © 2017 The International Society of Dermatology.

The effect of nightly nasal CPAP treatment on nocturnal hypoxemia and sleep disorders in mustard gas-injured patients.

PubMed

Vahedi, Ensieh; Fazeli Varzaneh, Ali Reza; Ghanei, Mostafa; Afsharpaiman, Shahla; Poursaleh, Zohre

2014-12-01

Sleep-related breathing disorders are associated with unusual respiratory pattern or an abnormal reduction in gas exchange during sleep that is common in sulfur mustard (SM) exposure. We compared 57 Iranian male patients injured with SM and had any complaints of sleep problems with an age-matched group of 21 Iranian male patients who had complaints of sleep problems and were not chemically injured; this group had Epworth Sleepiness Scale (ESS) above 10 and whom referred for polysomnography. Split-night studies were performed for patients with diagnostic polysomnography for obstructive sleep apnea (OSA) and respiratory events. We then studied respiratory events including episodes of OSA, apnea-hypopnea index (AHI) and respiratory disturbance index (RDI). The mean age in mustard-exposed patients was 48.14±8.04 years and in age-matched group, 48.19±8.39 years. In mustard exposed patients, there were statistical differences for the episodes of OSA (p=0.001), AHI (p=0.001), and RDI (p=0.001) between two segments of split-night studies. In the age-matched group, there were statistically differences for each parameter (episodes of OSA (p=0.001), AHI (p=0.001), and RDI (p=0.001)). There were no significant differences between two groups. This study indicated that the incidence of respiratory events and nocturnal hypoxemia during sleep in mustard-exposed patients were high and treatment with CPAP significantly reduced all these events.

External apical root resorption in maxillary root-filled incisors after orthodontic treatment: a split-mouth design study.

PubMed

Llamas-Carreras, José María; Amarilla, Almudena; Espinar-Escalona, Eduardo; Castellanos-Cosano, Lizett; Martín-González, Jenifer; Sánchez-Domínguez, Benito; López-Frías, Francisco Javier

2012-05-01

The purpose of this study was to compare, in a split mouth design, the external apical root resorption (EARR) associated with orthodontic treatment in root-filled maxillary incisors and their contralateral teeth with vital pulps. The study sample consisted of 38 patients (14 males and 24 females), who had one root-filled incisor before completion of multiband/bracket orthodontic therapy for at least 1 year. For each patient, digital panoramic radiographs taken before and after orthodontic treatment were used to determine the root resortion and the proportion of external root resorption (PRR), defined as the ratio between the root resorption in the endodontically treated incisor and that in its contralateral incisor with a vital pulp. The student's t-test, chi-square test and logistic regression analysis were used to determine statistical significance. There was no statistically significant difference (p > 0.05) between EARR in vital teeth (1.1 ± 1.0 mm) and endodontically treated incisors (1.1 ± 0.8 mm). Twenty-six patients (68.4%) showed greater resorption of the endodontically treated incisor than its homolog vital tooth (p > 0.05). The mean and standard deviation of PPR were 1.0 ± 0.2. Multivariate logistic regression suggested that PRR does not correlate with any of the variables analyzed. There was no significant difference in the amount or severity of external root resorption during orthodontic movement between root-filled incisors and their contralateral teeth with vital pulps.

Split-Face Comparison of an Advanced Non-Hydroquinone Lightening Solution to 4% Hydroquinone.

PubMed

Schlessinger, Joel; Saxena, Subhash; Mohr, Stuart

2016-12-01

Hyperpigmentation is a primary concern for many cosmetic patients because of its high rate of occurrence and significant impact on perceived age. While 4% hydroquinone has been the gold-standard of treatment, there is a growing interest in non-hydroquinone solutions, however, many of these newer solutions fail to deliver equivalent improvement. This double-blind, randomized, split-face study compares the effects of a new OTC non-hydroquinone lightening product (JM) to an available 4% hydroquinone lightening solution (OB) on the appearance of hyperpigmentation, texture, and ne lines and wrinkles. Comparisons were determined by both physician assessment and subject self-assessment at baseline, 4, 8, and 12 weeks. Physician assessment showed statistically equivalent improvement on both sides of the face with the JM side showing equivalent or superior average improvement in all assessed categories. Subject self-assessment showed a significant preference for the JM product over the 4% hydroquinone and a substantially higher perception of overall improvement over 4% hydroquinone (P=0.058). Physician assessment showed equal or superior average improvement in all measured categories with no statistically significant difference between the two sides. Subject self-assessment, however, showed a significant and growing preference toward the investigated JM product over the course of the study. Overall, the results of this study show the JM product to be equivalent if not superior to 4% hydroquinone for results and patient satisfaction. J Drugs Dermatol. 2016;15(12):1571-1577.

Academy Helps Army Be All that It Can Be.

ERIC Educational Resources Information Center

Holden, Constance

1987-01-01

Summarizes a report which attempted to determine the usefulness of various human potential technologies in military training programs. Includes information on sleep learning, accelerated learning, mental practice, biofeedback, group cohesion, split-brain effects, altered mental states, influence strategies, and parapsychology. (TW)

Graphene-based terahertz metasurface with tunable spectrum splitting.

PubMed

Su, Zhaoxian; Chen, Xuan; Yin, Jianbo; Zhao, Xiaopeng

2016-08-15

We design a tunable terahertz metasurface, which consists of two different trapezoid graphene ribbons patterned in opposite directions on a gold film, separated by a thin dielectric spacer. The two kinds of graphene ribbons can cover a nearly 2π phase shift with high reflection efficiency in different spectral regions so that the metasurface can reflect different frequency waves to totally different directions. By changing the Fermi level of the graphene ribbons, the response frequency of the proposed metasurface can be adjusted, and as a result, tunable spectrum splitting can be realized. The present metasurface provides a powerful way to control terahertz waves and has potential applications in wide-angle beam splitters.

Formation mechanism of TiO2 nanotubes and their applications in photoelectrochemical water splitting and supercapacitors.

PubMed

Chen, Bo; Hou, Junbo; Lu, Kathy

2013-05-14

Structural observations of the transition of TiO2 nanopores into nanotubes by increasing the OH(-) concentration in the electrolyte challenge the validity of existing formation mechanisms of anodic TiO2 nanotubes. In this study, dehydration of titanium hydroxide in the cell wall is proposed as the mechanism that leads to the separation of neighboring nanotubes. Based on this understanding, bamboo-type TiO2 nanotubes with large surface area and excellent interconnectivity are achieved by cycling high and low applied potentials. After thermal treatment in a H2 atmosphere, the bamboo-type TiO2 nanotubes show large photoelectrochemical water splitting efficiency and supercapacitors performace.

Research Update: Photoelectrochemical water splitting and photocatalytic hydrogen production using ferrites (MFe{sub 2}O{sub 4}) under visible light irradiation

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

Dillert, Ralf; Laboratorium für Nano- und Quantenengineering, Gottfried Wilhelm Leibniz Universität Hannover, Schneiderberg 39, 30167 Hannover; Taffa, Dereje H.

2015-10-01

The utilization of solar light for the photoelectrochemical and photocatalytic production of molecular hydrogen from water is a scientific and technical challenge. Semiconductors with suitable properties to promote solar-driven water splitting are a desideratum. A hitherto rarely investigated group of semiconductors are ferrites with the empirical formula MFe{sub 2}O{sub 4} and related compounds. This contribution summarizes the published results of the experimental investigations on the photoelectrochemical and photocatalytic properties of these compounds. It will be shown that the potential of this group of compounds in regard to the production of solar hydrogen has not been fully explored yet.

Sociology, economics, and gender: can knowledge of the past contribute to a better future?

PubMed

Nelson, Julie A

2010-01-01

This article explores the profoundly gendered nature of the split between the disciplines of economics and sociology that took place in the late 19th and early 20th centuries, emphasizing implications for current efforts to bring the fields more closely together. Drawing on historical documents and feminist studies of science, it investigates the gendered processes underlying the divergence of the disciplines in definition, method, and degree of engagement with social problems. The recently developed field of economic sociology and other efforts to bridge the disciplinary gap have the potential to heal this disciplinary split, if they are broadened, deepened, and made wiser and more self-reflective through the use of feminist analysis.

Study on photonic angular momentum states in coaxial magneto-optical waveguides

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

Yang, Mu; Wu, Li-Ting; Guo, Tian-Jing

2014-10-21

By rigorously solving Maxwell's equations, we develop a full-wave electromagnetic theory for the study of photonic angular momentum states (PAMSs) in coaxial magneto-optical (MO) waveguides. Paying attention to a metal-MO-metal coaxial configuration, we show that the dispersion curves of the originally degenerated PAMSs experience a splitting, which are determined by the off-diagonal permittivity tensor element of the MO medium. We emphasize that this broken degeneracy in dispersion relation is accompanied by modified distributions of field component and transverse energy flux. A qualitative analysis about the connection between the split dispersion behavior and the field distribution is provided. Potential applications aremore » discussed.« less

Generating and Separating Twisted Light by gradient-rotation Split-Ring Antenna Metasurfaces.

PubMed

Zeng, Jinwei; Li, Ling; Yang, Xiaodong; Gao, Jie

2016-05-11

Nanoscale compact optical vortex generators promise substantially significant prospects in modern optics and photonics, leading to many advances in sensing, imaging, quantum communication, and optical manipulation. However, conventional vortex generators often suffer from bulky size, low vortex mode purity in the converted beam, or limited operation bandwidth. Here, we design and demonstrate gradient-rotation split-ring antenna metasurfaces as unique spin-to-orbital angular momentum beam converters to simultaneously generate and separate pure optical vortices in a broad wavelength range. Our proposed design has the potential for realizing miniaturized on-chip OAM-multiplexers, as well as enabling new types of metasurface devices for the manipulation of complex structured light beams.

Statistical analysis of low level atmospheric turbulence

NASA Technical Reports Server (NTRS)

Tieleman, H. W.; Chen, W. W. L.

1974-01-01

The statistical properties of low-level wind-turbulence data were obtained with the model 1080 total vector anemometer and the model 1296 dual split-film anemometer, both manufactured by Thermo Systems Incorporated. The data obtained from the above fast-response probes were compared with the results obtained from a pair of Gill propeller anemometers. The digitized time series representing the three velocity components and the temperature were each divided into a number of blocks, the length of which depended on the lowest frequency of interest and also on the storage capacity of the available computer. A moving-average and differencing high-pass filter was used to remove the trend and the low frequency components in the time series. The calculated results for each of the anemometers used are represented in graphical or tabulated form.

StackSplit - a plugin for multi-event shear wave splitting analyses in SplitLab

NASA Astrophysics Data System (ADS)

Grund, Michael

2017-04-01

The SplitLab package (Wüstefeld et al., Computers and Geosciences, 2008), written in MATLAB, is a powerful and widely used tool for analysing seismological shear wave splitting of single event measurements. However, in many cases, especially temporary station deployments close to seaside or for recordings affected by strong anthropogenic noise, only multi-event approaches provide stable and reliable splitting results. In order to extend the original SplitLab environment for such analyses, I present the StackSplit plugin that can easily be implemented within the well accepted main program. StackSplit grants easy access to several different analysis approaches within SplitLab, including a new multiple waveform based inversion method as well as the most established standard stacking procedures. The possibility to switch between different analysis approaches at any time allows the user for the most flexible processing of individual multi-event splitting measurements for a single recording station. Besides the provided functions of the plugin, no other external program is needed for the multi-event analyses since StackSplit performs within the available SplitLab structure.

Algebraic techniques for diagonalization of a split quaternion matrix in split quaternionic mechanics

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

Jiang, Tongsong, E-mail: jiangtongsong@sina.com; Department of Mathematics, Heze University, Heze, Shandong 274015; Jiang, Ziwu

In the study of the relation between complexified classical and non-Hermitian quantum mechanics, physicists found that there are links to quaternionic and split quaternionic mechanics, and this leads to the possibility of employing algebraic techniques of split quaternions to tackle some problems in complexified classical and quantum mechanics. This paper, by means of real representation of a split quaternion matrix, studies the problem of diagonalization of a split quaternion matrix and gives algebraic techniques for diagonalization of split quaternion matrices in split quaternionic mechanics.

Towards large volume big divisor D3/D7 " μ-split supersymmetry" and Ricci-flat Swiss-cheese metrics, and dimension-six neutrino mass operators

NASA Astrophysics Data System (ADS)

Dhuria, Mansi; Misra, Aalok

2012-02-01

We show that it is possible to realize a " μ-split SUSY" scenario (Cheng and Cheng, 2005) [1] in the context of large volume limit of type IIB compactifications on Swiss-cheese Calabi-Yau orientifolds in the presence of a mobile space-time filling D3-brane and a (stack of) D7-brane(s) wrapping the "big" divisor. For this, we investigate the possibility of getting one Higgs to be light while other to be heavy in addition to a heavy higgsino mass parameter. Further, we examine the existence of long lived gluino that manifests one of the major consequences of μ-split SUSY scenario, by computing its decay width as well as lifetime corresponding to the three-body decays of the gluino into either a quark, a squark and a neutralino or a quark, squark and goldstino, as well as two-body decays of the gluino into either a neutralino and a gluon or a goldstino and a gluon. Guided by the geometric Kähler potential for Σ obtained in Misra and Shukla (2010) [2] based on GLSM techniques, and the Donaldson's algorithm (Barun et al., 2008) [3] for obtaining numerically a Ricci-flat metric, we give details of our calculation in Misra and Shukla (2011) [4] pertaining to our proposed metric for the full Swiss-cheese Calabi-Yau (the geometric Kähler potential being needed to be included in the full moduli space Kähler potential in the presence of the mobile space-time filling D3-brane), but for simplicity of calculation, close to the big divisor, which is Ricci-flat in the large volume limit. Also, as an application of the one-loop RG flow solution for the higgsino mass parameter, we show that the contribution to the neutrino masses at the EW scale from dimension-six operators arising from the Kähler potential, is suppressed relative to the Weinberg-type dimension-five operators.

3D structured Mo-doped Ni3S2 nanosheets as efficient dual-electrocatalyst for overall water splitting

NASA Astrophysics Data System (ADS)

Wu, Chengrong; Liu, Bitao; Wang, Jun; Su, Yongyao; Yan, Hengqing; Ng, Chuntan; Li, Cheng; Wei, Jumeng

2018-05-01

Searching for a cost-effective, high efficient and stable bifunctional electrocatalyst for overall water-splitting is critical to renewable energy systems. In this study, three-dimensional (3D) curved nanosheets of Mo-doped Ni3S2 grown on nickel foam were successfully synthesized via a one-step hydrothermal process. The hydrogen-evolution reaction (HER) and the oxygen-evolution reaction (OER) in alkaline environment of this 3D catalyst are investigated in detail. The results show that it possesses lower overpotential, high current densities and small Tafel slopes both in OER and HER. For HER, the catalysts show excellent electrochemical performance, demonstrating a low over-potential of 212 mV at 10 mA cm-2 with a large decrease of 127 mV compared to the undoped Ni3S2. And it also shows a lower overpotential of 260 mV at 10 mA cm-2 which decreases 30 mV for OER. In addition, it is only need 1.67 V for the overall water splitting at 10 mA cm-2 which is 70 mV. It found that the Mo element would change the morphology of Ni3S2 and induce much more active sites for HER and OER. The as-prepared Mo-doped Ni3S2 bi-functional electrocatalyst could act as the promising electrode materials for water splitting.

Ternary electrocatalysts for oxidizing ethanol to carbon dioxide: making ir capable of splitting C-C bond.

PubMed

Li, Meng; Cullen, David A; Sasaki, Kotaro; Marinkovic, Nebojsa S; More, Karren; Adzic, Radoslav R

2013-01-09

Splitting the C-C bond is the main obstacle to electrooxidation of ethanol (EOR) to CO(2). We recently demonstrated that the ternary PtRhSnO(2) electrocatalyst can accomplish that reaction at room temperature with Rh having a unique capability to split the C-C bond. In this article, we report the finding that Ir can be induced to split the C-C bond as a component of the ternary catalyst. We characterized and compared the properties of several carbon-supported nanoparticle (NP) electrocatalysts comprising a SnO(2) NP core decorated with multimetallic nanoislands (MM' = PtIr, PtRh, IrRh, PtIrRh) prepared using a seeded growth approach. An array of characterization techniques were employed to establish the composition and architecture of the synthesized MM'/SnO(2) NPs, while electrochemical and in situ infrared reflection absorption spectroscopy studies elucidated trends in activity and the nature of the reaction intermediates and products. Both EOR reactivity and selectivity toward CO(2) formation of several of these MM'/SnO(2)/C electrocatalysts are significantly higher compared to conventional Pt/C and Pt/SnO(2)/C catalysts. We demonstrate that the PtIr/SnO(2)/C catalyst with high Ir content shows outstanding catalytic properties with the most negative EOR onset potential and reasonably good selectivity toward ethanol complete oxidation to CO(2).

Surface modifications of chalcopyrite CuInS2 thin films for photochatodes in photoelectrochemical water splitting under sunlight irradiation

NASA Astrophysics Data System (ADS)

Gunawan; Haris, A.; Widiyandari, H.; Septina, W.; Ikeda, S.

2017-02-01

Copper chalcopyrite semiconductors include a wide range of compounds that are of interest for photoelectrochemical water splitting which enables them to be used as photochatodes for H2 generation. Among them, CuInS2 is one of the most important materials due to its optimum band gap energy for sunlight absorption. In the present study, we investigated the application of CuInS2 fabricated by electrodeposition as photochatodes for water splitting. Thin film of CuInS2 chalcopyrite was formed on Mo-coated glass substrate by stacked electrodeposition of copper and indium followed by sulfurization under H2S flow. The films worked as a H2 liberation electrode under cathodic polarization from a solution containing Na2SO4 after loading Pt deposits on the film. Introduction of an n-type CdS layer by chemical bath deposition on the CuInS2 surface before the Pt loading resulted appreciable improvements of H2 liberation efficiency and a higher photocurrent onset potential. Moreover, the use of In2S3 layer as an alternative n-type layer to the CdS significantly improved the H2 liberation performance: the CuInS2 film modified with In2S3 and Pt deposits worked as an efficient photocathode for photoelectrochemical water splitting.

Constraints on the Dip of the Anisotropic Symmetry Axis Beneath Japan From Shear Wave Splitting

NASA Astrophysics Data System (ADS)

Long, M. D.; Chevrot, S.; van der Hilst, R.

2001-12-01

Shear wave splitting is widely used as a tool to characterize deformational signatures in the upper mantle. However, we nearly always make the simplifying assumption that the axis of symmetry of the anisotropy is horizontal, which may not always be correct. Due to the nearly vertical incidence angles of the SKS phases typically used in splitting studies, the dip of the symmetry axis is difficult to characterize. However, if phases with varying angles of incidence are used, constraints may be placed on the dip of the symmetry axis. Splitting measurements made on upgoing shear waves with different incidence angles should exhibit discrepancies if the axis of symmetry is not horizontal. Therefore, recordings of SKKS, S, and ScS phases in addition to SKS may be used to constrain the dip of the axis of anisotropic symmetry. Japan is an excellent candidate region to potentially exhibit such discrepancies; deformation associated with the subduction beneath Japan could reasonably be expected to produce a dipping axis of symmetry. In addition, Japan is favorably located with respect to suitable source regions and data from several dense broadband seismic networks are available. We examine data from several high-quality, low-noise stations from the FREESIA network, a network of 62 broadband stations in Japan. We search for good recordings of events in the 0o-60o distance range for ScS, from 40o-80o for S, from 90o-130ofor SKS, and beyond 105o for SKKS. Only deep (>200km) events are used for S and ScS to eliminate contamination from source-side anisotropy. The multichannel method of Chevrot (JGR 2000) is used to determine splitting parameters (φ , δ t) at each station for each phase. Splitting parameters are determined from the azimuthal dependence of the splitting intensity; the method is therefore limited by the azimuthal coverage. Japan has relatively poor azimuthal coverage for SKS and SKKS, and this limits the usefulness of the multichannel method for this dataset. Splitting parameters for SKS and SKKS phases may also be determined using the method of Silver & Chan (JGR 1991). Azimuthal coverage for deep events in the distance ranges associated with S and ScS, however, is quite good and this favorable coverage makes Japan a good place to carry out such a study. We investigate the discrepancies between measured splitting parameters for S, ScS, SKS, and SKKS. We will present preliminary results of the modeling of such discrepancies in terms of a dipping axis and discuss to what extent this can be explained by the presence of a dipping slab.

Influence of the large-small split effect on strategy choice in complex subtraction.

PubMed

Xiang, Yan Hui; Wu, Hao; Shang, Rui Hong; Chao, Xiaomei; Ren, Ting Ting; Zheng, Li Ling; Mo, Lei

2018-04-01

Two main theories have been used to explain the arithmetic split effect: decision-making process theory and strategy choice theory. Using the inequality paradigm, previous studies have confirmed that individuals tend to adopt a plausibility-checking strategy and a whole-calculation strategy to solve large and small split problems in complex addition arithmetic, respectively. This supports strategy choice theory, but it is unknown whether this theory also explains performance in solving different split problems in complex subtraction arithmetic. This study used small, intermediate and large split sizes, with each split condition being further divided into problems requiring and not requiring borrowing. The reaction times (RTs) for large and intermediate splits were significantly shorter than those for small splits, while accuracy was significantly higher for large and middle splits than for small splits, reflecting no speed-accuracy trade-off. Further, RTs and accuracy differed significantly between the borrow and no-borrow conditions only for small splits. This study indicates that strategy choice theory is suitable to explain the split effect in complex subtraction arithmetic. That is, individuals tend to choose the plausibility-checking strategy or the whole-calculation strategy according to the split size. © 2016 International Union of Psychological Science.

StackSplit - a plugin for multi-event shear wave splitting analyses in SplitLab

NASA Astrophysics Data System (ADS)

Grund, Michael

2017-08-01

SplitLab is a powerful and widely used tool for analysing seismological shear wave splitting of single event measurements. However, in many cases, especially temporary station deployments close to the noisy seaside, ocean bottom or for recordings affected by strong anthropogenic noise, only multi-event approaches provide stable and reliable splitting results. In order to extend the original SplitLab environment for such analyses, I present the StackSplit plugin that can easily be implemented within the well accepted main program. StackSplit grants easy access to several different analysis approaches within SplitLab, including a new multiple waveform based inversion method as well as the most established standard stacking procedures. The possibility to switch between different analysis approaches at any time allows the user for the most flexible processing of individual multi-event splitting measurements for a single recording station. Besides the provided functions of the plugin, no other external program is needed for the multi-event analyses since StackSplit performs within the available SplitLab structure which is based on MATLAB. The effectiveness and use of this plugin is demonstrated with data examples of a long running seismological recording station in Finland.

Synthesis and photo-electrochemical properties of spinel-ferrite-coated hematite for solar water splitting

NASA Astrophysics Data System (ADS)

Selvaraj, Seenivasan; Moon, Hee; Kim, Do-Heyoung

2018-01-01

Photo-electrochemical water splitting with hematite photo-anodes under solar irradiation has attracted considerable attention as regards the production of renewable hydrogen energy. However, many challenges remain unresolved, as the full contribution of the catalytic over-layers has not been fully realized. Herein, we incorporate uniform spinel nickel-ferrite over-layers in hematite photo-anodes to obtain an improved understanding of the associated intrinsic changes. We achieve a 1.5-mA/cm2 photo-current density at 1.23 VRHE (RHE: reversible hydrogen electrode) under one-sun illumination conditions, along with a negative shift of 200 mV in the onset potential, for NiFe2O4-coated Sn-doped hematite photo-anodes. Fundamental electrochemical analyses clearly show that the shift in the onset potential is predominantly due to the enhanced photo-voltage development inside the hematite, rather than being purely caused by the interfacial kinetics. These insights reveal a new direction for fundamental research on photo-anodes towards fabrication of more efficient photo-anode systems.

A New Global Potential Energy Surface for the Hydroperoxyl Radical, HO2: Reaction Coefficients for H + O2 and Vibrational Splittings for H Atom Transfer

NASA Technical Reports Server (NTRS)

Dateo, Christopher E.; Arnold, James O. (Technical Monitor)

1994-01-01

A new analytic global potential energy surface describing the hydroperoxyl radical system H((sup 2)S) + O2(X (sup 3)Sigma((sup -)(sub g))) (reversible reaction) HO2 ((X-tilde) (sup 2)A'') (reversible reaction) O((sup 3)P) + O H (X (sup 2)Pi) has been fitted using the ab initio complete active space SCF (self-consistent-field)/externally contracted configuration interaction (CASSCF/CCI) energy calculations of Walch and Duchovic. Results of quasiclassical trajectory studies to determine the rate coefficients of the forward and reverse reactions at combustion temperatures will be presented. In addition, vibrational energy levels were calculated using the quantum DVR-DGB (discrete variable representation-distributed Gaussian basis) method and the splitting due to H atom migration is investigated. The material of the proposed presentation was reviewed and the technical content will not reveal any information not already in the public domain and will not give any foreign industry or government a competitive advantage.

Forcing function modeling for flow induced vibration

NASA Technical Reports Server (NTRS)

Fleeter, Sanford

1993-01-01

The fundamental forcing function unsteady aerodynamics for application to turbomachine blade row forced response are considered, accomplished through a series of experiments performed in a rotating annular cascade and a research axial flow turbine. In particular, the unsteady periodic flowfields downstream of rotating rows of perforated plates, airfoils and turbine blade rows are measured with a cross hot-wire and an unsteady total pressure probe. The unsteady velocity and static pressure fields were then analyzed harmonically and split into vortical and potential gusts, accomplished by developing a gust splitting analysis which includes both gust unsteady static pressure and velocity data. The perforated plate gusts closely were found to be linear theory vortical gusts, satisfying the vortical gust constraints. The airfoil and turbine blade row generated velocity perturbations did not satisfy the vortical gust constraints. However, the decomposition of the unsteady flow field separated the data into a propagating vortical component which satisfied these vortical gust constraints and a decaying potential component.

Characterization of azimuthal and longitudinal modes in rolled-up InGaAs/GaAs microtubes at telecom wavelengths.

PubMed

Zhong, Qiuhang; Tian, Zhaobing; Dastjerdi, M Hadi Tavakoli; Mi, Zetian; Plant, David V

2013-08-12

We report on theoretical and experimental investigation of azimuthal and longitudinal modes in rolled-up microtubes at telecom wavelengths. These microtubes are fabricated by selectively releasing a coherently strained InGaAs/GaAs bilayer. We apply planar waveguide method and a quasi-potential model to analyze the azimuthal and longitudinal modes in the microtubes near 1550 nm. Then we demonstrate these modes in transmission spectrum by evanescent light coupling. The experimental observations agree well with the calculated results. Surface-scattering-induced mode splitting is also observed in both transmission and reflection spectra at ~1600 nm. The mode splitting is in essence the non-degeneracy of clockwise and counter-clockwise whispering-gallery modes of the microtubes. This study is significant for understanding the physics of modes in microtubes and other microcavities with three-dimensional optical confinement, as well as for potential applications such as microtube-based photonic integrated devices and sensing purposes.

Detecting deep sea hydrothermal vents with a split-beam echosounder

NASA Astrophysics Data System (ADS)

Gray, L. M.; Jerram, K.

2016-12-01

In May 2016, the NOAA Office of Exploration and Research exploration vessel, Okeanos Explorer, conducted a remotely operated vehicle (ROV) dive on a series of active `black smoker' hydrothermal vents at 3,300 m depth in the western Pacific Ocean near the Mariana Trench. The ROV system traversed 800 m along the seafloor and detected three distinct vent sites. The vent chimneys ranged in heights from 5 m to 30 m above the seafloor and vent fluid temperatures were measured as high as 337 °C. Immediately following the ROV dive, the Okeanos Explorer mapped the vent field with an 18 kHz split-beam echosounder traditionally used for fishery research and a 30 kHz multibeam echosounder with midwater capability. Six passes were made over the field, transiting at 4-5 knots on various headings. There was a clear and repeatable signal in the split-beam echogram from the venting but less obvious indication in the multibeam data. `Black smokers' have traditionally been detected using repeat conductivity-temperature-depth (CTD) `tow-yo' casts. Our field observations suggest an alternative, and potentially more efficient, method of detecting hydrothermal vent plumes within the beamwidth of the split-beam echosounder to inform ROV dive plans. Methods previously applied for locating marine gas seeps on the seafloor with split-beam echosounders can be applied to estimate the hydrothermal vent positions in this dataset and compared to the recorded ROV positions at each site. Additionally, assuming relatively stable venting and ambient conditions, the ROV position and CTD data recorded from the vehicles can be used to better understand the observed midwater acoustic backscatter signatures of the hydrothermal vent plumes.

Photosynthetic water splitting by the Mn4Ca2+OX catalyst of photosystem II: its structure, robustness and mechanism.

PubMed

Barber, James

2017-01-01

The biological energy cycle of our planet is driven by photosynthesis whereby sunlight is absorbed by chlorophyll and other accessory pigments. The excitation energy is then efficiently transferred to a reaction centre where charge separation occurs in a few picoseconds. In the case of photosystem II (PSII), the energy of the charge transfer state is used to split water into oxygen and reducing equivalents. This is accomplished by the relatively low energy content of four photons of visible light. PSII is a large multi-subunit membrane protein complex embedded in the lipid environment of the thylakoid membranes of plants, algae and cyanobacteria. Four high energy electrons, together with four protons (4H+), are used to reduce plastoquinone (PQ), the terminal electron acceptor of PSII, to plastoquinol (PQH2). PQH2 passes its reducing equivalents to an electron transfer chain which feeds into photosystem I (PSI) where they gain additional reducing potential from a second light reaction which is necessary to drive CO2 reduction. The catalytic centre of PSII consists of a cluster of four Mn ions and a Ca2+ linked by oxo bonds. In addition, there are seven amino acid ligands. In this Article, I discuss the structure of this metal cluster, its stability and the probability that an acid-base (nucleophilic-electrophilic) mechanism catalyses the water splitting reaction on the surface of the metal-cluster. Evidence for this mechanism is presented from studies on water splitting catalysts consisting of organo-complexes of ruthenium and manganese and also by comparison with the enzymology of carbon monoxide dehydrogenase (CODH). Finally the relevance of our understanding of PSII is discussed in terms of artificial photosynthesis with emphasis on inorganic water splitting catalysts as oxygen generating photoelectrodes.

Temperature- and pressure-dependent infrared spectroscopy of 1-butyl-3-methylimidazolium trifluoromethanesulfonate: A dipolar coupling theory analysis

NASA Astrophysics Data System (ADS)

Burba, Christopher M.; Chang, Hai-Chou

2018-03-01

Continued growth and development of ionic liquids requires a thorough understanding of how cation and anion molecular structure defines the liquid structure of the materials as well as the various properties that make them technologically useful. Infrared spectroscopy is frequently used to assess molecular-level interactions among the cations and anions of ionic liquids because the intramolecular vibrational modes of the ions are sensitive to the local potential energy environments in which they reside. Thus, different interaction modes among the ions may lead to different spectroscopic signatures in the vibrational spectra. Charge organization present in ionic liquids, such as 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4mim]CF3SO3), is frequently modeled in terms of a quasicrystalline structure. Highly structured quasilattices enable the dynamic coupling of vibrationally-induced dipole moments to produce optical dispersion and transverse optical-longitudinal optical (TO-LO) splitting of vibrational modes of the ionic liquid. According to dipolar coupling theory, the degree of TO-LO splitting is predicted to have a linear dependence on the number density of the ionic liquid. Both temperature and pressure will affect the number density of the ionic liquid and, therefore, the amount of TO-LO splitting for this mode. Therefore, we test these relationships through temperature- and pressure-dependent FT-IR spectroscopic studies of [C4mim]CF3SO3, focusing on the totally symmetric Ssbnd O stretching mode for the anion, νs(SO3). Increased temperature decreases the amount of TO-LO splitting for νs(SO3), whereas elevated pressure is found to increase the amount of band splitting. In both cases, the experimental observations follow the general predictions of dipolar coupling theory, thereby supporting the quasilattice model for this ionic liquid.

Upper mantle anisotropy beneath Peru from SKS splitting: Constraints on flat slab dynamics and interaction with the Nazca Ridge

NASA Astrophysics Data System (ADS)

Eakin, Caroline M.; Long, Maureen D.; Wagner, Lara S.; Beck, Susan L.; Tavera, Hernando

2015-02-01

The Peruvian flat slab is by far the largest region of flat subduction in the world today, but aspects of its structure and dynamics remain poorly understood. In particular, questions remain over whether the relatively narrow Nazca Ridge subducting beneath southern Peru provides dynamic support for the flat slab or it is just a passive feature. We investigate the dynamics and interaction of the Nazca Ridge and the flat slab system by studying upper mantle seismic anisotropy across southern Peru. We analyze shear wave splitting of SKS, sSKS, and PKS phases at 49 stations distributed across the area, primarily from the PerU Lithosphere and Slab Experiment (PULSE). We observe distinct spatial variations in anisotropic structure along strike, most notably a sharp transition from coherent splitting in the north to pervasive null (non-split) arrivals in the south, with the transition coinciding with the northern limit of the Nazca Ridge. For both anisotropic domains there is evidence for complex and multi-layered anisotropy. To the north of the ridge our *KS splitting measurements likely reflect trench-normal mantle flow beneath the flat slab. This signal is then modified by shallower anisotropic layers, most likely in the supra-slab mantle, but also potentially from within the slab. To the south the sub-slab mantle is similarly anisotropic, with a trench-oblique fast direction, but widespread nulls appear to reflect dramatic heterogeneity in anisotropic structure above the flat slab. Overall the regional anisotropic structure, and thus the pattern of deformation, appears to be closely tied to the location of the Nazca Ridge, which further suggests that the ridge plays a key role in the mantle dynamics of the Peruvian flat slab system.

Modeling the risk of phosphorus runoff following single and split phosphorus fertilizer applications in two contrasting catchments.

PubMed

Burkitt, Lucy L; Dougherty, Warwick J; Corkrey, Ross; Broad, Shane T

2011-01-01

The potential loss of P in runoff is a function of the combined effects of fertilizer-soil interactions and climatic characteristics. In this study, we applied a Bayesian approach to experimental data to model the annualized long-term risk of P runoff following single and split P fertilizer applications using two example catchments with contrasting rainfall/runoff patterns. Split P fertilizer strategies are commonly used in intensive pasture production in Australia and our results showed that three applications of 13.3 kg P ha(-1) resulted in a greater risk of P runoff compared with a single application of 40 kg P ha(-1) when long-term surface runoff data were incorporated into a Bayesian P risk model. Splitting P fertilizer applications increased the likelihood of a coincidence of fertilizer application and runoff occurring. We found that the overall risk of P runoff is also increased in catchments where the rainfall/runoff pattern is less predictable, compared with catchments where rainfall/runoff is winter dominant. The findings of our study also question the effectiveness of current recommendations to avoid applying fertilizer if runoff is likely to occur in the next few days, as we found that total P concentrations at the half-life were still very high (18.2 and 8.2 mg P L(-1)) following single and split P treatments, respectively. Data from the current study also highlight that omitting P fertilizer on soils that already have adequate soil test P concentrations is an effective method of reducing P loss in surface runoff. If P fertilizer must be applied, we recommend less frequent applications and only during periods of the year when the risk of surface P runoff is low.

Strong gravitational lensing statistics as a test of cosmogonic scenarios

NASA Technical Reports Server (NTRS)

Cen, Renyue; Gott, J. Richard, III; Ostriker, Jeremiah P.; Turner, Edwin L.

1994-01-01

Gravitational lensing statistics can provide a direct and powerful test of cosmic structure formation theories. Since lensing tests, directly, the magnitude of the nonlinear mass density fluctuations on lines of sight to distant objects, no issues of 'bias' (of mass fluctuations with respect to galaxy density fluctuations) exist here, although lensing observations provide their own ambiguities of interpretation. We develop numerical techniques for generating model density distributions with the very large spatial dynamic range required by lensing considerations and for identifying regions of the simulations capable of multiple image lensing in a conservative and computationally efficient way that should be accurate for splittings significantly larger than 3 seconds. Applying these techniques to existing standard Cold dark matter (CDM) (Omega = 1) and Primeval Baryon Isocurvature (PBI) (Omega = 0.2) simulations (normalized to the Cosmic Background Explorer Satellite (COBE) amplitude), we find that the CDM model predicts large splitting (greater than 8 seconds) lensing events roughly an order-of-magnitude more frequently than the PBI model. Under the reasonable but idealized assumption that lensing structrues can be modeled as singular isothermal spheres (SIS), the predictions can be directly compared to observations of lensing events in quasar samples. Several large splitting (Delta Theta is greater than 8 seconds) cases are predicted in the standard CDM model (the exact number being dependent on the treatment of amplification bias), whereas none is observed. In a formal sense, the comparison excludes the CDM model at high confidence (essentially for the same reason that CDM predicts excessive small-scale cosmic velocity dispersions.) A very rough assessment of low-density but flat CDM model (Omega = 0.3, Lambda/3H(sup 2 sub 0) = 0.7) indicates a far lower and probably acceptable level of lensing. The PBI model is consistent with, but not strongly tested by, the available lensing data, and other open models would presumably do as well as PBI. These preliminary conclusions and the assumptions on which they are based can be tested and the analysis can be applied to other cosmogonic models by straightforward extension of the work presented here.

Mesenchymal Stem Cells and Platelet Gel Improve Bone Deposition within CAD-CAM Custom-Made Ceramic HA Scaffolds for Condyle Substitution

PubMed Central

Ciocca, L.; Donati, D.; Ragazzini, S.; Dozza, B.; Rossi, F.; Fantini, M.; Spadari, A.; Romagnoli, N.; Landi, E.; Tampieri, A.; Piattelli, A.; Iezzi, G.; Scotti, R.

2013-01-01

Purpose. This study evaluated the efficacy of a regenerative approach using mesenchymal stem cells (MSCs) and CAD-CAM customized pure and porous hydroxyapatite (HA) scaffolds to replace the temporomandibular joint (TMJ) condyle. Methods. Pure HA scaffolds with a 70% total porosity volume were prototyped using CAD-CAM technology to replace the two temporomandibular condyles (left and right) of the same animal. MSCs were derived from the aspirated iliac crest bone marrow, and platelets were obtained from the venous blood of the sheep. Custom-made surgical guides were created by direct metal laser sintering and were used to export the virtual planning of the bone cut lines into the surgical environment. Sheep were sacrificed 4 months postoperatively. The HA scaffolds were explanted, histological specimens were prepared, and histomorphometric analysis was performed. Results. Analysis of the porosity reduction for apposition of newly formed bone showed a statistically significant difference in bone formation between condyles loaded with MSC and condyles without (P < 0.05). The bone ingrowth (BI) relative values of split-mouth comparison (right versus left side) showed a significant difference between condyles with and without MSCs (P < 0.05). Analysis of the test and control sides in the same animal using a split-mouth study design was performed; the condyle with MSCs showed greater bone formation. Conclusion. The split-mouth design confirmed an increment of bone regeneration into the HA scaffold of up to 797% upon application of MSCs. PMID:24073409

Mesenchymal stem cells and platelet gel improve bone deposition within CAD-CAM custom-made ceramic HA scaffolds for condyle substitution.

PubMed

Ciocca, L; Donati, D; Ragazzini, S; Dozza, B; Rossi, F; Fantini, M; Spadari, A; Romagnoli, N; Landi, E; Tampieri, A; Piattelli, A; Iezzi, G; Scotti, R

2013-01-01

This study evaluated the efficacy of a regenerative approach using mesenchymal stem cells (MSCs) and CAD-CAM customized pure and porous hydroxyapatite (HA) scaffolds to replace the temporomandibular joint (TMJ) condyle. Pure HA scaffolds with a 70% total porosity volume were prototyped using CAD-CAM technology to replace the two temporomandibular condyles (left and right) of the same animal. MSCs were derived from the aspirated iliac crest bone marrow, and platelets were obtained from the venous blood of the sheep. Custom-made surgical guides were created by direct metal laser sintering and were used to export the virtual planning of the bone cut lines into the surgical environment. Sheep were sacrificed 4 months postoperatively. The HA scaffolds were explanted, histological specimens were prepared, and histomorphometric analysis was performed. Analysis of the porosity reduction for apposition of newly formed bone showed a statistically significant difference in bone formation between condyles loaded with MSC and condyles without (P < 0.05). The bone ingrowth (BI) relative values of split-mouth comparison (right versus left side) showed a significant difference between condyles with and without MSCs (P < 0.05). Analysis of the test and control sides in the same animal using a split-mouth study design was performed; the condyle with MSCs showed greater bone formation. The split-mouth design confirmed an increment of bone regeneration into the HA scaffold of up to 797% upon application of MSCs.

Analysis of a Split-Plot Experimental Design Applied to a Low-Speed Wind Tunnel Investigation

NASA Technical Reports Server (NTRS)

Erickson, Gary E.

2013-01-01

A procedure to analyze a split-plot experimental design featuring two input factors, two levels of randomization, and two error structures in a low-speed wind tunnel investigation of a small-scale model of a fighter airplane configuration is described in this report. Standard commercially-available statistical software was used to analyze the test results obtained in a randomization-restricted environment often encountered in wind tunnel testing. The input factors were differential horizontal stabilizer incidence and the angle of attack. The response variables were the aerodynamic coefficients of lift, drag, and pitching moment. Using split-plot terminology, the whole plot, or difficult-to-change, factor was the differential horizontal stabilizer incidence, and the subplot, or easy-to-change, factor was the angle of attack. The whole plot and subplot factors were both tested at three levels. Degrees of freedom for the whole plot error were provided by replication in the form of three blocks, or replicates, which were intended to simulate three consecutive days of wind tunnel facility operation. The analysis was conducted in three stages, which yielded the estimated mean squares, multiple regression function coefficients, and corresponding tests of significance for all individual terms at the whole plot and subplot levels for the three aerodynamic response variables. The estimated regression functions included main effects and two-factor interaction for the lift coefficient, main effects, two-factor interaction, and quadratic effects for the drag coefficient, and only main effects for the pitching moment coefficient.

Correcting for Optimistic Prediction in Small Data Sets

PubMed Central

Smith, Gordon C. S.; Seaman, Shaun R.; Wood, Angela M.; Royston, Patrick; White, Ian R.

2014-01-01

The C statistic is a commonly reported measure of screening test performance. Optimistic estimation of the C statistic is a frequent problem because of overfitting of statistical models in small data sets, and methods exist to correct for this issue. However, many studies do not use such methods, and those that do correct for optimism use diverse methods, some of which are known to be biased. We used clinical data sets (United Kingdom Down syndrome screening data from Glasgow (1991–2003), Edinburgh (1999–2003), and Cambridge (1990–2006), as well as Scottish national pregnancy discharge data (2004–2007)) to evaluate different approaches to adjustment for optimism. We found that sample splitting, cross-validation without replication, and leave-1-out cross-validation produced optimism-adjusted estimates of the C statistic that were biased and/or associated with greater absolute error than other available methods. Cross-validation with replication, bootstrapping, and a new method (leave-pair-out cross-validation) all generated unbiased optimism-adjusted estimates of the C statistic and had similar absolute errors in the clinical data set. Larger simulation studies confirmed that all 3 methods performed similarly with 10 or more events per variable, or when the C statistic was 0.9 or greater. However, with lower events per variable or lower C statistics, bootstrapping tended to be optimistic but with lower absolute and mean squared errors than both methods of cross-validation. PMID:24966219

Fierz bilinear formulation of the Maxwell–Dirac equations and symmetry reductions

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

Inglis, Shaun, E-mail: sminglis@utas.edu.au; Jarvis, Peter, E-mail: Peter.Jarvis@utas.edu.au

We study the Maxwell–Dirac equations in a manifestly gauge invariant presentation using only the spinor bilinear scalar and pseudoscalar densities, and the vector and pseudovector currents, together with their quadratic Fierz relations. The internally produced vector potential is expressed via algebraic manipulation of the Dirac equation, as a rational function of the Fierz bilinears and first derivatives (valid on the support of the scalar density), which allows a gauge invariant vector potential to be defined. This leads to a Fierz bilinear formulation of the Maxwell tensor and of the Maxwell–Dirac equations, without any reference to gauge dependent quantities. We showmore » how demanding invariance of tensor fields under the action of a fixed (but arbitrary) Lie subgroup of the Poincaré group leads to symmetry reduced equations. The procedure is illustrated, and the reduced equations worked out explicitly for standard spherical and cylindrical cases, which are coupled third order nonlinear PDEs. Spherical symmetry necessitates the existence of magnetic monopoles, which do not affect the coupled Maxwell–Dirac system due to magnetic terms cancelling. In this paper we do not take up numerical computations. As a demonstration of the power of our approach, we also work out the symmetry reduced equations for two distinct classes of dimension 4 one-parameter families of Poincaré subgroups, one splitting and one non-splitting. The splitting class yields no solutions, whereas for the non-splitting class we find a family of formal exact solutions in closed form. - Highlights: • Maxwell–Dirac equations derived in manifestly gauge invariant tensor form. • Invariant scalar and four vector fields for four Poincaré subgroups derived, including two unusual cases. • Symmetry reduction imposed on Maxwell–Dirac equations under example subgroups. • Magnetic monopole arises for spherically symmetric case, consistent with charge quantization condition.« less

Statistical evolution of quiet-Sun small-scale magnetic features using Sunrise observations

NASA Astrophysics Data System (ADS)

Anusha, L. S.; Solanki, S. K.; Hirzberger, J.; Feller, A.

2017-02-01

The evolution of small magnetic features in quiet regions of the Sun provides a unique window for probing solar magneto-convection. Here we analyze small-scale magnetic features in the quiet Sun, using the high resolution, seeing-free observations from the Sunrise balloon borne solar observatory. Our aim is to understand the contribution of different physical processes, such as splitting, merging, emergence and cancellation of magnetic fields to the rearrangement, addition and removal of magnetic flux in the photosphere. We have employed a statistical approach for the analysis and the evolution studies are carried out using a feature-tracking technique. In this paper we provide a detailed description of the feature-tracking algorithm that we have newly developed and we present the results of a statistical study of several physical quantities. The results on the fractions of the flux in the emergence, appearance, splitting, merging, disappearance and cancellation qualitatively agrees with other recent studies. To summarize, the total flux gained in unipolar appearance is an order of magnitude larger than the total flux gained in emergence. On the other hand, the bipolar cancellation contributes nearly an equal amount to the loss of magnetic flux as unipolar disappearance. The total flux lost in cancellation is nearly six to eight times larger than the total flux gained in emergence. One big difference between our study and previous similar studies is that, thanks to the higher spatial resolution of Sunrise, we can track features with fluxes as low as 9 × 1014 Mx. This flux is nearly an order of magnitude lower than the smallest fluxes of the features tracked in the highest resolution previous studies based on Hinode data. The area and flux of the magnetic features follow power-law type distribution, while the lifetimes show either power-law or exponential type distribution depending on the exact definitions used to define various birth and death events. We have also statistically determined the evolution of the flux within the features in the course of their lifetime, finding that this evolution depends very strongly on the birth and death process that the features undergo.

Generation and control of polarization-entangled photons from GaAs island quantum dots by an electric field

PubMed Central

Ghali, Mohsen; Ohtani, Keita; Ohno, Yuzo; Ohno, Hideo

2012-01-01

Semiconductor quantum dots are potential sources for generating polarization-entangled photons efficiently. The main prerequisite for such generation based on biexciton–exciton cascaded emission is to control the exciton fine-structure splitting. Among various techniques investigated for this purpose, an electric field is a promising means to facilitate the integration into optoelectronic devices. Here we demonstrate the generation of polarization-entangled photons from single GaAs quantum dots by an electric field. In contrast to previous studies, which were limited to In(Ga)As quantum dots, GaAs island quantum dots formed by a thickness fluctuation were used because they exhibit a larger oscillator strength and emit light with a shorter wavelength. A forward voltage was applied to a Schottky diode to control the fine-structure splitting. We observed a decrease and suppression in the fine-structure splitting of the studied single quantum dot with the field, which enabled us to generate polarization-entangled photons with a high fidelity of 0.72±0.05. PMID:22314357

Dye-Sensitized Hydrobromic Acid Splitting for Hydrogen Solar Fuel Production.

PubMed

Brady, Matthew D; Sampaio, Renato N; Wang, Degao; Meyer, Thomas J; Meyer, Gerald J

2017-11-08

Hydrobromic acid (HBr) has significant potential as an inexpensive feedstock for hydrogen gas (H 2 ) solar fuel production through HBr splitting. Mesoporous thin films of anatase TiO 2 or SnO 2 /TiO 2 core-shell nanoparticles were sensitized to visible light with a new Ru II polypyridyl complex that served as a photocatalyst for bromide oxidation. These thin films were tested as photoelectrodes in dye-sensitized photoelectrosynthesis cells. In 1 N HBr (aq), the photocatalyst undergoes excited-state electron injection and light-driven Br - oxidation. The injected electrons induce proton reduction at a Pt electrode. Under 100 mW cm -2 white-light illumination, sustained photocurrents of 1.5 mA cm -2 were measured under an applied bias. Faradaic efficiencies of 71 ± 5% for Br - oxidation and 94 ± 2% for H 2 production were measured. A 12 μmol h -1 sustained rate of H 2 production was maintained during illumination. The results demonstrate a molecular approach to HBr splitting with a visible light absorbing complex capable of aqueous Br - oxidation and excited-state electron injection.

Strong Landau-quantization effects in high-magnetic-field superconductivity of a two-dimensional multiple-band metal near the Lifshitz transition

DOE PAGES

Song, Kok Wee; Koshelev, Alexei E.

2017-05-04

We investigate the onset of superconductivity in a magnetic field for a clean two-dimensional multiple-band superconductor in the vicinity of the Lifshitz transition when one of the bands is very shallow. Due to the small number of carriers in this band, the quasiclassical Werthamer-Helfand approximation breaks down and Landau quantization has to be taken into account. We found that the transition temperature T C2( H) has giant oscillations and is resonantly enhanced at the magnetic fields corresponding to the matching of the chemical potential with the Landau levels in the shallow band. This enhancement is especially pronounced for the lowestmore » Landau level. As a consequence, the reentrant superconducting regions in the temperature-field phase diagram emerge at low temperatures near the magnetic fields at which the shallow-band Landau levels cross the chemical potential. The specific behavior depends on the relative strength of the intraband and interband pairing interactions and the reentrance is most pronounced in the purely interband coupling scenario. The reentrant behavior is suppressed by the Zeeman spin splitting in the shallow band; the separated regions disappear already for very small spin-splitting factors. On the other hand, the reentrance is restored in the resonance cases when the spin-splitting energy exactly matches the separation between the Landau levels. As a result, the predicted behavior may be realized in the gate-tuned FeSe monolayer.« less

Strong Landau-quantization effects in high-magnetic-field superconductivity of a two-dimensional multiple-band metal near the Lifshitz transition

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

Song, Kok Wee; Koshelev, Alexei E.

We investigate the onset of superconductivity in a magnetic field for a clean two-dimensional multiple-band superconductor in the vicinity of the Lifshitz transition when one of the bands is very shallow. Due to the small number of carriers in this band, the quasiclassical Werthamer-Helfand approximation breaks down and Landau quantization has to be taken into account. We found that the transition temperature T C2( H) has giant oscillations and is resonantly enhanced at the magnetic fields corresponding to the matching of the chemical potential with the Landau levels in the shallow band. This enhancement is especially pronounced for the lowestmore » Landau level. As a consequence, the reentrant superconducting regions in the temperature-field phase diagram emerge at low temperatures near the magnetic fields at which the shallow-band Landau levels cross the chemical potential. The specific behavior depends on the relative strength of the intraband and interband pairing interactions and the reentrance is most pronounced in the purely interband coupling scenario. The reentrant behavior is suppressed by the Zeeman spin splitting in the shallow band; the separated regions disappear already for very small spin-splitting factors. On the other hand, the reentrance is restored in the resonance cases when the spin-splitting energy exactly matches the separation between the Landau levels. As a result, the predicted behavior may be realized in the gate-tuned FeSe monolayer.« less

Quantifying kinematic differences between land and water during squats, split squats, and single-leg squats in a healthy population.

PubMed

Severin, Anna C; Burkett, Brendan J; McKean, Mark R; Wiegand, Aaron N; Sayers, Mark G L

2017-01-01

Aquatic exercises can be used in clinical and sporting disciplines for both rehabilitation and sports training. However, there is limited knowledge on the influence of water immersion on the kinematics of exercises commonly used in rehabilitation and fitness programs. The aim of this study was to use inertial sensors to quantify differences in kinematics and movement variability of bodyweight squats, split squats, and single-leg squats performed on dry land and whilst immersed to the level of the greater trochanter. During two separate testing sessions, 25 active healthy university students (22.3±2.9 yr.) performed ten repetitions of each exercise, whilst tri-axial inertial sensors (100 Hz) recorded their trunk and lower body kinematics. Repeated-measures statistics tested for differences in segment orientation and speed, movement variability, and waveform patterns between environments, while coefficient of variance was used to assess differences in movement variability. Between-environment differences in segment orientation and speed were portrayed by plotting the mean difference ±95% confidence intervals (CI) throughout the tasks. The results showed that the depth of the squat and split squat were unaffected by the changed environment while water immersion allowed for a deeper single leg squat. The different environments had significant effects on the sagittal plane orientations and speeds for all segments. Water immersion increased the degree of movement variability of the segments in all exercises, except for the shank in the frontal plane, which showed more variability on land. Without compromising movement depth, the aquatic environment induces more upright trunk and shank postures during squats and split squats. The aquatic environment allows for increased squat depth during the single-leg squat, and increased shank motions in the frontal plane. Our observations therefore support the use of water-based squat tasks for rehabilitation as they appear to improve the technique without compromising movement depth.

Quantifying kinematic differences between land and water during squats, split squats, and single-leg squats in a healthy population

PubMed Central

2017-01-01

Aquatic exercises can be used in clinical and sporting disciplines for both rehabilitation and sports training. However, there is limited knowledge on the influence of water immersion on the kinematics of exercises commonly used in rehabilitation and fitness programs. The aim of this study was to use inertial sensors to quantify differences in kinematics and movement variability of bodyweight squats, split squats, and single-leg squats performed on dry land and whilst immersed to the level of the greater trochanter. During two separate testing sessions, 25 active healthy university students (22.3±2.9 yr.) performed ten repetitions of each exercise, whilst tri-axial inertial sensors (100 Hz) recorded their trunk and lower body kinematics. Repeated-measures statistics tested for differences in segment orientation and speed, movement variability, and waveform patterns between environments, while coefficient of variance was used to assess differences in movement variability. Between-environment differences in segment orientation and speed were portrayed by plotting the mean difference ±95% confidence intervals (CI) throughout the tasks. The results showed that the depth of the squat and split squat were unaffected by the changed environment while water immersion allowed for a deeper single leg squat. The different environments had significant effects on the sagittal plane orientations and speeds for all segments. Water immersion increased the degree of movement variability of the segments in all exercises, except for the shank in the frontal plane, which showed more variability on land. Without compromising movement depth, the aquatic environment induces more upright trunk and shank postures during squats and split squats. The aquatic environment allows for increased squat depth during the single-leg squat, and increased shank motions in the frontal plane. Our observations therefore support the use of water-based squat tasks for rehabilitation as they appear to improve the technique without compromising movement depth. PMID:28767683

Comment on: "Split kinetic energy method for quantum systems with competing potentials", Ann. Phys. 327 (2012) 2061

NASA Astrophysics Data System (ADS)

Fernández, Francisco M.

2018-06-01

We show that the kinetic-energy partition method (KEP) is a particular example of the well known Rayleigh-Ritz variational method. We discuss some of the KEP results and compare them with those coming from other approaches.

High-resolution simulations of unstable cylindrical gravity currents undergoing wandering and splitting motions in a rotating system

NASA Astrophysics Data System (ADS)

Dai, Albert; Wu, Ching-Sen

2018-02-01

High-resolution simulations of unstable cylindrical gravity currents when wandering and splitting motions occur in a rotating system are reported. In this study, our attention is focused on the situation of unstable rotating cylindrical gravity currents when the ratio of Coriolis to inertia forces is larger, namely, 0.5 ≤ C ≤ 2.0, in comparison to the stable ones when C ≤ 0.3 as investigated previously by the authors. The simulations reproduce the major features of the unstable rotating cylindrical gravity currents observed in the laboratory, i.e., vortex-wandering or vortex-splitting following the contraction-relaxation motion, and good agreement is found when compared with the experimental results on the outrush radius of the advancing front and on the number of bulges. Furthermore, the simulations provide energy budget information which could not be attained in the laboratory. After the heavy fluid is released, the heavy fluid collapses and a contraction-relaxation motion is at work for approximately 2-3 revolutions of the system. During the contraction-relaxation motion of the heavy fluid, the unstable rotating cylindrical gravity currents behave similar to the stable ones. Towards the end of the contraction-relaxation motion, the dissipation rate in the system reaches a local minimum and a quasi-geostrophic equilibrium state is reached. After the quasi-geostrophic equilibrium state, vortex-wandering or vortex-splitting may occur depending on the ratio of Coriolis to inertia forces. The vortex-splitting process begins with non-axisymmetric bulges and, as the bulges grow, the kinetic energy increases at the expense of decreasing potential energy in the system. The completion of vortex-splitting is accompanied by a local maximum of dissipation rate and a local maximum of kinetic energy in the system. A striking feature of the unstable rotating cylindrical gravity currents is the persistent upwelling and downwelling motions, which are observed for both the vortex-wandering and vortex-splitting motions and were not previously documented for such flows. Depending on the Reynolds number, the bulges around the circumference of the unstable rotating cylindrical gravity currents may or may not develop into cutoff distinct circulations. The number of bulges is seen to be dependent on the ratio of Coriolis to inertia forces but independent of the Reynolds number for the range of Reynolds number considered in this study.

Real-time three-dimensional imaging of epidermal splitting and removal by high-definition optical coherence tomography.

PubMed

Boone, Marc; Draye, Jean Pierre; Verween, Gunther; Pirnay, Jean-Paul; Verbeken, Gilbert; De Vos, Daniel; Rose, Thomas; Jennes, Serge; Jemec, Gregor B E; Del Marmol, Véronique

2014-10-01

While real-time 3-D evaluation of human skin constructs is needed, only 2-D non-invasive imaging techniques are available. The aim of this paper is to evaluate the potential of high-definition optical coherence tomography (HD-OCT) for real-time 3-D assessment of the epidermal splitting and decellularization. Human skin samples were incubated with four different agents: Dispase II, NaCl 1 M, sodium dodecyl sulphate (SDS) and Triton X-100. Epidermal splitting, dermo-epidermal junction, acellularity and 3-D architecture of dermal matrices were evaluated by High-definition optical coherence tomography before and after incubation. Real-time 3-D HD-OCT assessment was compared with 2-D en face assessment by reflectance confocal microscopy (RCM). (Immuno) histopathology was used as control. HD-OCT imaging allowed real-time 3-D visualization of the impact of selected agents on epidermal splitting, dermo-epidermal junction, dermal architecture, vascular spaces and cellularity. RCM has a better resolution (1 μm) than HD-OCT (3 μm), permitting differentiation of different collagen fibres, but HD-OCT imaging has deeper penetration (570 μm) than RCM imaging (200 μm). Dispase II and NaCl treatments were found to be equally efficient in the removal of the epidermis from human split-thickness skin allografts. However, a different epidermal splitting level at the dermo-epidermal junction could be observed and confirmed by immunolabelling of collagen type IV and type VII. Epidermal splitting occurred at the level of the lamina densa with dispase II and above the lamina densa (in the lamina lucida) with NaCl. The 3-D architecture of dermal papillae and dermis was more affected by Dispase II on HD-OCT which corresponded with histopathologic (orcein staining) fragmentation of elastic fibres. With SDS treatment, the epidermal removal was incomplete as remnants of the epidermal basal cell layer remained attached to the basement membrane on the dermis. With Triton X-100 treatment, the epidermis was not removed. In conclusion, HD-OCT imaging permits real-time 3-D visualization of the impact of selected agents on human skin allografts. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

On-demand acoustic droplet splitting and steering in a disposable microfluidic chip.

PubMed

Park, Jinsoo; Jung, Jin Ho; Park, Kwangseok; Destgeer, Ghulam; Ahmed, Husnain; Ahmad, Raheel; Sung, Hyung Jin

2018-01-30

On-chip droplet splitting is one of the fundamental droplet-based microfluidic unit operations to control droplet volume after production and increase operational capability, flexibility, and throughput. Various droplet splitting methods have been proposed, and among them the acoustic droplet splitting method is promising because of its label-free operation without any physical or thermal damage to droplets. Previous acoustic droplet splitting methods faced several limitations: first, they employed a cross-type acoustofluidic device that precluded multichannel droplet splitting; second, they required irreversible bonding between a piezoelectric substrate and a microfluidic chip, such that the fluidic chip was not replaceable. Here, we present a parallel-type acoustofluidic device with a disposable microfluidic chip to address the limitations of previous acoustic droplet splitting devices. In the proposed device, an acoustic field is applied in the direction opposite to the flow direction to achieve multichannel droplet splitting and steering. A disposable polydimethylsiloxane microfluidic chip is employed in the developed device, thereby removing the need for permanent bonding and improving the flexibility of the droplet microfluidic device. We experimentally demonstrated on-demand acoustic droplet bi-splitting and steering with precise control over the droplet splitting ratio, and we investigated the underlying physical mechanisms of droplet splitting and steering based on Laplace pressure and ray acoustics analyses, respectively. We also demonstrated droplet tri-splitting to prove the feasibility of multichannel droplet splitting. The proposed on-demand acoustic droplet splitting device enables on-chip droplet volume control in various droplet-based microfluidic applications.

Self-Replication of Localized Vegetation Patches in Scarce Environments

PubMed Central

Bordeu, Ignacio; Clerc, Marcel G.; Couteron, Piere; Lefever, René; Tlidi, Mustapha

2016-01-01

Desertification due to climate change and increasing drought periods is a worldwide problem for both ecology and economy. Our ability to understand how vegetation manages to survive and propagate through arid and semiarid ecosystems may be useful in the development of future strategies to prevent desertification, preserve flora—and fauna within—or even make use of scarce resources soils. In this paper, we study a robust phenomena observed in semi-arid ecosystems, by which localized vegetation patches split in a process called self-replication. Localized patches of vegetation are visible in nature at various spatial scales. Even though they have been described in literature, their growth mechanisms remain largely unexplored. Here, we develop an innovative statistical analysis based on real field observations to show that patches may exhibit deformation and splitting. This growth mechanism is opposite to the desertification since it allows to repopulate territories devoid of vegetation. We investigate these aspects by characterizing quantitatively, with a simple mathematical model, a new class of instabilities that lead to the self-replication phenomenon observed. PMID:27650430

Singlet-triplet splittings and their relevance to the spin-dependent exciton formation in light-emitting polymers: an EOM/CCSD study.

PubMed

Chen, Liping; Zhu, Lingyun; Shuai, Zhigang

2006-12-21

By employing the coupled-cluster equation of motion method (EOM/CCSD) for excited-state structures, we have investigated the structure dependence of the singlet and triplet exciton splittings, through extensive calculations for polythiophene (PT), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(thienylenevinylene) (PTV), polyparaphenylene vinylene (PPV), MEHPPV, polyparaphenylene ethylene (PPE), polyfluorene (PFO), and ladder-type polyparaphenylene (mLPPP). The results for the polymer are extrapolated through computations for the oligomers with increasing length. Recent investigations have been quite controversial about whether the internal quantum efficiency of electroluminescence could be higher than the 25% spin statistics limit or not in polymeric materials. Using a simple relationship between the exciton formation rate and the excitation energy level, we have discussed the material-dependent ratios of singlet and triplet exciton formation, which are in good agreement with the magnetic-field resonance detected transient spectroscopy measurement by Wohlgenannt et al. for a series of electronic polymers. This provides another piece of evidence to support the view that the internal quantum efficiency for conjugated polymers can exceed the 25% limit.

Probabilistic Approach to Enable Extreme-Scale Simulations under Uncertainty and System Faults. Final Technical Report

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

Knio, Omar

2017-05-05

The current project develops a novel approach that uses a probabilistic description to capture the current state of knowledge about the computational solution. To effectively spread the computational effort over multiple nodes, the global computational domain is split into many subdomains. Computational uncertainty in the solution translates into uncertain boundary conditions for the equation system to be solved on those subdomains, and many independent, concurrent subdomain simulations are used to account for this bound- ary condition uncertainty. By relying on the fact that solutions on neighboring subdomains must agree with each other, a more accurate estimate for the global solutionmore » can be achieved. Statistical approaches in this update process make it possible to account for the effect of system faults in the probabilistic description of the computational solution, and the associated uncertainty is reduced through successive iterations. By combining all of these elements, the probabilistic reformulation allows splitting the computational work over very many independent tasks for good scalability, while being robust to system faults.« less

Magnetophonon resonance in double quantum wells

NASA Astrophysics Data System (ADS)

Ploch, D.; Sheregii, E. M.; Marchewka, M.; Wozny, M.; Tomaka, G.

2009-05-01

The experimental results obtained for the magnetotransport in pulsed magnetic fields in the InGaAs/InAlAs double quantum well (DQW) structures of two different shapes of wells and different values of the electron density are reported. The magnetophonon resonance (MPR) was observed for both types of structures within the temperature range 77-125 K. Four kinds of LO phonons are taken into account to interpret the MPR oscillations in the DQW and a method of the Landau level calculation in the DQW is elaborated for this aim. The peculiarity of the MPR in the DQW is the large number of the Landau levels caused by SAS splitting of the electron states (splitting on the symmetric and anti-symmetric states) and the large number of the phonon assistance electron transitions between Landau levels. The significant role of the carrier statistics is shown too. The behavior of the electron states in the DQWs at comparably high temperatures has been studied using the MPR. It is shown that the Huang and Manasreh [Manasreh [Phys. Rev. B 54, 2044 (1996)] model involving screening of exchange interaction is confirmed.

Bending and splitting of spoof surface acoustic waves through structured rigid surface

NASA Astrophysics Data System (ADS)

Xie, Sujun; Ouyang, Shiliang; He, Zhaojian; Wang, Xiaoyun; Deng, Ke; Zhao, Heping

2018-03-01

In this paper, we demonstrated that a 90°-bended imaging of spoof surface acoustic waves with subwavelength resolution of 0.316λ can be realized by a 45° prism-shaped surface phononic crystal (SPC), which is composed of borehole arrays with square lattice in a rigid plate. Furthermore, by combining two identical prism-shaped phononic crystal to form an interface (to form a line-defect), the excited spoof surface acoustic waves can be split into bended and transmitted parts. The power ratio between the bended and transmitted surface waves can be tuned arbitrarily by adjusting the defect size. This acoustic system is believed to have potential applications in various multifunctional acoustic solutions integrated by different acoustical devices.

A boundary element model of the transport of a semi-infinite bubble through a microvessel bifurcation

NASA Astrophysics Data System (ADS)

Calderon, Andres J.; Eshpuniyani, Brijesh; Fowlkes, J. Brian; Bull, Joseph L.

2010-06-01

Motivated by a developmental gas embolotherapy technique for selective occlusion of blood flow to tumors, we examined the transport of a pressure-driven semi-infinite bubble through a liquid-filled bifurcating channel. Homogeneity of bubble splitting as the bubble passes through a vessel bifurcation affects the degree to which the vascular network near the tumor can be uniformly occluded. The homogeneity of bubble splitting was found to increase with bubble driving pressure and to decrease with increased bifurcation angle. Viscous losses at the bifurcation were observed to affect the bubble speed significantly. The potential for oscillating bubble interfaces to induce flow recirculation and impart high stresses on the vessel endothelium was also observed.

An implicit fast Fourier transform method for integration of the time dependent Schrodinger equation

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

Riley, M.E.; Ritchie, A.B.

1997-12-31

One finds that the conventional exponentiated split operator procedure is subject to difficulties when solving the time-dependent Schrodinger equation for Coulombic systems. By rearranging the kinetic and potential energy terms in the temporal propagator of the finite difference equations, one can find a propagation algorithm for three dimensions that looks much like the Crank-Nicholson and alternating direction implicit methods for one- and two-space-dimensional partial differential equations. The authors report investigations of this novel implicit split operator procedure. The results look promising for a purely numerical approach to certain electron quantum mechanical problems. A charge exchange calculation is presented as anmore » example of the power of the method.« less

Successful management of angiolymphoid hyperplasia with eosinophilia in a split-face trial of topical tacrolimus and timolol solution.

PubMed

Chacon, Anna; Mercer, Jessica

2016-08-01

Angiolymphoid hyperplasia with eosinophilia (ALHE) is an uncommon, benign condition characterized by multiple benign angiomatous nodules or plaques. Cutaneous lesions can be painful, pruritic, pulsatile, or potentially disfiguring resulting in significant morbidity. ALHE is a pathologic diagnosis featuring proliferations of capillary-sized vessels with epithelioid endothelial cells surrounded by larger, thick-walled vessels and accompanying eosinophils and lymphocytes. Surgery is generally required, however the skin lesions often recur after excision. ALHE is notoriously difficult to treat and many physicians would prefer a non-invasive treatment of choice. We report a case of ALHE that was successfully treated with the novel use of topical tacrolimus in a split-face trial with topical timolol solution.

Experimental evidence of hot carriers solar cell operation in multi-quantum wells heterostructures

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

Rodière, Jean; Lombez, Laurent, E-mail: laurent.lombez@chimie-paristech.fr; Le Corre, Alain

We investigated a semiconductor heterostructure based on InGaAsP multi quantum wells (QWs) using optical characterizations and demonstrate its potential to work as a hot carrier cell absorber. By analyzing photoluminescence spectra, the quasi Fermi level splitting Δμ and the carrier temperature are quantitatively measured as a function of the excitation power. Moreover, both thermodynamics values are measured at the QWs and the barrier emission energy. High values of Δμ are found for both transition, and high carrier temperature values in the QWs. Remarkably, the quasi Fermi level splitting measured at the barrier energy exceeds the absorption threshold of the QWs.more » This indicates a working condition beyond the classical Shockley-Queisser limit.« less

Metamaterial split ring resonator as a sensitive mechanical vibration sensor

NASA Astrophysics Data System (ADS)

Sikha Simon, K.; Chakyar, Sreedevi P.; Andrews, Jolly; Joseph V., P.

2017-06-01

This paper introduces a sensitive vibration sensor based on microwave metamaterial Split Ring Resonator (SRR) capable of detecting any ground vibration. The experimental setup consists of single Broad-side Coupled SRR (BCSRR) unit fixed on a cantilever capable of sensitive vibrations. It is arranged between transmitting and receiving probes of a microwave measurement system. The absorption level variations at the resonant frequency due to the displacement from the reference plane of SRR, which is a function of the strength of external mechanical vibration, is analyzed. This portable and cost effective sensor working on a single frequency is observed to be capable of detecting even very weak vibrations. This may find potential applications in the field of tamper-proofing, mining, quarrying and earthquake sensing.

Fracture patterns after bilateral sagittal split osteotomy of the mandibular ramus according to the Obwegeser/Dal Pont and Hunsuck/Epker modifications.

PubMed

Möhlhenrich, Stephan Christian; Kniha, Kristian; Peters, Florian; Ayoub, Nassim; Goloborodko, Evgeny; Hölzle, Frank; Fritz, Ulrike; Modabber, Ali

2017-05-01

The aim of this study was to compare the fracture patterns after sagittal split osteotomy according to Obwegeser/Dal Pont (ODP) and Hunsuck/Epker (HE), as well as to investigate the relationship between lateral bone cut ending or angle and the incidence of unfavorable/bad splits. Postoperative cone-beam computed tomograms of 124 splits according to ODP and 60 according to HE were analyzed. ODP led to 75.8% and HE led to 60% lingual fractures with mandibular foramen contact. Horizontal fractures were found in 9.7% and 6.7%, respectively, and unfavorable/bad splits were found in 11.3% and 10%, respectively. The lateral osteotomy angle was 106.22° (SD 12.03)° for bad splits and 106.6° (SD 13.12)° for favorable splits. Correlations were found between favorable fracture patterns and split modifications and between buccal ending of the lateral bone cut and bad splits (p < 0.001). No relationship was observed between split modifications (p = 0.792) or the osteotomy angle (p = 0.937) and the incidence of unfavorable/bad splits. Split modifications had no influence on the incidence of unfavorable/bad splits, but the buccal ending of the lateral bone cut did have an influence. More lingual fractures with mandibular foramen contact are expected with the ODP modification. The osteotomy angle did not differ between favorable and bad splits. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Clinical application of calculated split renal volume using computed tomography-based renal volumetry after partial nephrectomy: Correlation with technetium-99m dimercaptosuccinic acid renal scan data.

PubMed

Lee, Chan Ho; Park, Young Joo; Ku, Ja Yoon; Ha, Hong Koo

2017-06-01

To evaluate the clinical application of computed tomography-based measurement of renal cortical volume and split renal volume as a single tool to assess the anatomy and renal function in patients with renal tumors before and after partial nephrectomy, and to compare the findings with technetium-99m dimercaptosuccinic acid renal scan. The data of 51 patients with a unilateral renal tumor managed by partial nephrectomy were retrospectively analyzed. The renal cortical volume of tumor-bearing and contralateral kidneys was measured using ImageJ software. Split estimated glomerular filtration rate and split renal volume calculated using this renal cortical volume were compared with the split renal function measured with technetium-99m dimercaptosuccinic acid renal scan. A strong correlation between split renal function and split renal volume of the tumor-bearing kidney was observed before and after surgery (r = 0.89, P < 0.001 and r = 0.94, P < 0.001). The preoperative and postoperative split estimated glomerular filtration rate of the operated kidney showed a moderate correlation with split renal function (r = 0.39, P = 0.004 and r = 0.49, P < 0.001). The correlation between reductions in split renal function and split renal volume of the operated kidney (r = 0.87, P < 0.001) was stronger than that between split renal function and percent reduction in split estimated glomerular filtration rate (r = 0.64, P < 0.001). The split renal volume calculated using computed tomography-based renal volumetry had a strong correlation with the split renal function measured using technetium-99m dimercaptosuccinic acid renal scan. Computed tomography-based split renal volume measurement before and after partial nephrectomy can be used as a single modality for anatomical and functional assessment of the tumor-bearing kidney. © 2017 The Japanese Urological Association.

Split-mouth comparison of the accuracy of computer-generated and conventional surgical guides.

PubMed

Farley, Nathaniel E; Kennedy, Kelly; McGlumphy, Edwin A; Clelland, Nancy L

2013-01-01

Recent clinical studies have shown that implant placement is highly predictable with computer-generated surgical guides; however, the reliability of these guides has not been compared to that of conventional guides clinically. This study aimed to compare the accuracy of reproducing planned implant positions with computer-generated and conventional surgical guides using a split-mouth design. Ten patients received two implants each in symmetric locations. All implants were planned virtually using a software program and information from cone beam computed tomographic scans taken with scan appliances in place. Patients were randomly selected for computer-aided design/computer-assisted manufacture (CAD/CAM)-guided implant placement on their right or left side. Conventional guides were used on the contralateral side. Patients underwent operative cone beam computed tomography postoperatively. Planned and actual implant positions were compared using three-dimensional analyses capable of measuring volume overlap as well as differences in angles and coronal and apical positions. Results were compared using a mixed-model repeated-measures analysis of variance and were further analyzed using a Bartlett test for unequal variance (α = .05). Implants placed with CAD/CAM guides were closer to the planned positions in all eight categories examined. However, statistically significant differences were shown only for coronal horizontal distances. It was also shown that CAD/CAM guides had less variability than conventional guides, which was statistically significant for apical distance. Implants placed using CAD/CAM surgical guides provided greater accuracy in a lateral direction than conventional guides. In addition, CAD/CAM guides were more consistent in their deviation from the planned locations than conventional guides.

Comparative Evaluation of Efficacy of Physics Forceps versus Conventional Forceps in Orthodontic Extractions: A Prospective Randomized Split Mouth Study.

PubMed

Patel, Harsh S; Managutti, Anil M; Menat, Shailesh; Agarwal, Arvind; Shah, Dishan; Patel, Jigar

2016-07-01

Tooth extraction is one of the most commonly performed procedures in dentistry. It is usually a traumatic procedure often resulting in immediate destruction and loss of alveolar bone and surrounding soft tissues. Various instruments have been described to perform atraumatic extractions which can prevent damage to the paradental structures. Recently developed physics forceps is one of the instruments which is claimed to perform atraumatic extractions. The aim of the present study was to compare the efficacy of physics forceps with conventional forceps in terms of operating time, prevention of marginal bone loss & soft tissue loss, postoperative pain and postoperative complications following bilateral premolar extractions for orthodontic purpose. In this prospective split-mouth study, outcomes of the 2 groups (n = 42 premolars) requiring extraction of premolars for orthodontic treatment purpose using Physics forceps and Conventional forceps were compared. Clinical outcomes in form of time taken, loss of buccal soft tissue and buccal cortical plate based on extraction defect classification system, postoperative pain and other complication associated with extraction were recorded and compared. Statistically significant reduction in the operating time was noted in physics forceps group. Marginal bone loss and soft tissue loss was also significantly lesser in physics forceps group when compared to conventional forceps group. However, there was no statistically significant difference in severity of postoperative pain between both groups. The results of the present study suggest that physics forceps was more efficient in reducing operating time and prevention of marginal bone loss & soft tissue loss when compared to conventional forceps in orthodontically indicated premolar extractions.

External apical root resorption in maxillary root-filled incisors after orthodontic treatment: A split-mouth design study

PubMed Central

Amarilla, Almudena; Espinar-Escalona, Eduardo; Castellanos-Cosano, Lizett; Martín-González, Jenifer; Sánchez-Domínguez, Benito; López-Frías, Francisco J.

2012-01-01

Introduction: The purpose of this study was to compare, in a split mouth design, the external apical root resorption (EARR) associated with orthodontic treatment in root-filled maxillary incisors and their contralateral teeth with vital pulps. Methodology: The study sample consisted of 38 patients (14 males and 24 females), who had one root-filled incisor before completion of multiband/bracket orthodontic therapy for at least 1 year. For each patient, digital panoramic radiographs taken before and after orthodontic treatment were used to determine the root resortion and the proportion of external root resorption (PRR), defined as the ratio between the root resorption in the endodontically treated incisor and that in its contralateral incisor with a vital pulp. The student’s t-test, chi-square test and logistic regression analysis were used to determine statistical significance. Results: There was no statistically significant difference (p > 0.05) between EARR in vital teeth (1.1 ± 1.0 mm) and endodontically treated incisors (1.1 ± 0.8 mm). Twenty-six patients (68.4%) showed greater resorption of the endodontically treated incisor than its homolog vital tooth (p > 0.05). The mean and standard deviation of PPR were 1.0 ± 0.2. Multivariate logistic regression suggested that PRR does not correlate with any of the variables analyzed. Conclusions: There was no significant difference in the amount or severity of external root resorption during orthodontic movement between root-filled incisors and their contralateral teeth with vital pulps. Key words:Endodontics, orthodontics, root canal treatment, root resorption. PMID:22143731

Optical signal splitting and chirping device modeling

NASA Astrophysics Data System (ADS)

Vinogradova, Irina L.; Andrianova, Anna V.; Meshkov, Ivan K.; Sultanov, Albert Kh.; Abdrakhmanova, Guzel I.; Grakhova, Elizaveta P.; Ishmyarov, Arsen A.; Yantilina, Liliya Z.; Kutlieva, Gulnaz R.

2017-04-01

This article examines the devices for optical signal splitting and chirping device modeling. Models with splitting and switching functions are taken into consideration. The described device for optical signal splitting and chirping represents interferential splitter with profiled mixer which provides allocation of correspondent spectral component from ultra wide band frequency diapason, and signal phase shift for aerial array (AA) directive diagram control. This paper proposes modeling for two types of devices for optical signal splitting and chirping: the interference-type optical signal splitting and chirping device and the long-distance-type optical signal splitting and chirping device.

Fee Splitting among General Practitioners: A Cross-Sectional Study in Iran.

PubMed

Parsa, Mojtaba; Larijani, Bagher; Aramesh, Kiarash; Nedjat, Saharnaz; Fotouhi, Akbar; Yekaninejad, Mir Saeed; Ebrahimian, Nejatollah; Kandi, Mohamad Jafar

2016-12-01

Fee splitting is a process whereby a physician refers a patient to another physician or a healthcare facility and receives a portion of the charge in return. This survey was conducted to study general practitioners' (GPs) attitudes toward fee splitting as well as the prevalence, causes, and consequences of this process. This is a cross-sectional study on 223 general practitioners in 2013. Concerning the causes and consequences of fee splitting, an unpublished qualitative study was conducted by interviewing a number of GPs and specialists and the questionnaire options were the results of the information obtained from this study. Of the total 320 GPs, 247 returned the questionnaires. The response rate was 77.18%. Of the 247 returned questionnaires, 223 fulfilled the inclusion criteria. Among the participants, 69.1% considered fee splitting completely wrong and 23.2% (frequently or rarely) practiced fee splitting. The present study showed that the prevalence of fee splitting among physicians who had positive attitudes toward fee splitting was 4.63 times higher than those who had negative attitudes. In addition, this study showed that, compared to private hospitals, fee splitting is less practiced in public hospitals. The major cause of fee splitting was found to be unrealistic/unfair tariffs and the main consequence of fee splitting was thought to be an increase in the number of unnecessary patient referrals. Fee splitting is an unethical act, contradicts the goals of the medical profession, and undermines patient's best interest. In Iran, there is no code of ethics on fee splitting, but in this study, it was found that the majority of GPs considered it unethical. However, among those who had negative attitudes toward fee splitting, there were physicians who did practice fee splitting. The results of the study showed that physicians who had a positive attitude toward fee splitting practiced it more than others. Therefore, if physicians consider fee splitting unethical, its rate will certainly decrease. The study claims that to decrease such practice, the healthcare system has to revise the tariffs.

TH-CD-202-04: Evaluation of Virtual Non-Contrast Images From a Novel Split-Filter Dual-Energy CT Technique

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

Huang, J; Szczykutowicz, T; Bayouth, J

Purpose: To compare the ability of two dual-energy CT techniques, a novel split-filter single-source technique of superior temporal resolution against an established sequential-scan technique, to remove iodine contrast from images with minimal impact on CT number accuracy. Methods: A phantom containing 8 tissue substitute materials and vials of varying iodine concentrations (1.7–20.1 mg I /mL) was imaged using a Siemens Edge CT scanner. Dual-energy virtual non-contrast (VNC) images were generated using the novel split-filter technique, in which a 120kVp spectrum is filtered by tin and gold to create high- and low-energy spectra with < 1 second temporal separation between themore » acquisition of low- and high-energy data. Additionally, VNC images were generated with the sequential-scan technique (80 and 140kVp) for comparison. CT number accuracy was evaluated for all materials at 15, 25, and 35mGy CTDIvol. Results: The spectral separation was greater for the sequential-scan technique than the split-filter technique with dual-energy ratios of 2.18 and 1.26, respectively. Both techniques successfully removed iodine contrast, resulting in mean CT numbers within 60HU of 0HU (split-filter) and 40HU of 0HU (sequential-scan) for all iodine concentrations. Additionally, for iodine vials of varying diameter (2–20 mm) with the same concentration (9.9 mg I /mL), the system accurately detected iodine for all sizes investigated. Both dual-energy techniques resulted in reduced CT numbers for bone materials (by >400HU for the densest bone). Increasing the imaging dose did not improve the CT number accuracy for bone in VNC images. Conclusion: VNC images from the split-filter technique successfully removed iodine contrast. These results demonstrate a potential for improving dose calculation accuracy and reducing patient imaging dose, while achieving superior temporal resolution in comparison sequential scans. For both techniques, inaccuracies in CT numbers for bone materials necessitate consideration for radiation therapy treatment planning.« less

Local error estimates for adaptive simulation of the Reaction–Diffusion Master Equation via operator splitting

PubMed Central

Hellander, Andreas; Lawson, Michael J; Drawert, Brian; Petzold, Linda

2015-01-01

The efficiency of exact simulation methods for the reaction-diffusion master equation (RDME) is severely limited by the large number of diffusion events if the mesh is fine or if diffusion constants are large. Furthermore, inherent properties of exact kinetic-Monte Carlo simulation methods limit the efficiency of parallel implementations. Several approximate and hybrid methods have appeared that enable more efficient simulation of the RDME. A common feature to most of them is that they rely on splitting the system into its reaction and diffusion parts and updating them sequentially over a discrete timestep. This use of operator splitting enables more efficient simulation but it comes at the price of a temporal discretization error that depends on the size of the timestep. So far, existing methods have not attempted to estimate or control this error in a systematic manner. This makes the solvers hard to use for practitioners since they must guess an appropriate timestep. It also makes the solvers potentially less efficient than if the timesteps are adapted to control the error. Here, we derive estimates of the local error and propose a strategy to adaptively select the timestep when the RDME is simulated via a first order operator splitting. While the strategy is general and applicable to a wide range of approximate and hybrid methods, we exemplify it here by extending a previously published approximate method, the Diffusive Finite-State Projection (DFSP) method, to incorporate temporal adaptivity. PMID:26865735

Microbubble transport through a bifurcating vessel network with pulsatile flow.

PubMed

Valassis, Doug T; Dodde, Robert E; Esphuniyani, Brijesh; Fowlkes, J Brian; Bull, Joseph L

2012-02-01

Motivated by two-phase microfluidics and by the clinical applications of air embolism and a developmental gas embolotherapy technique, experimental and theoretical models of microbubble transport in pulsatile flow are presented. The one-dimensional time-dependent theoretical model is developed from an unsteady Bernoulli equation that has been modified to include viscous and unsteady effects. Results of both experiments and theory show that roll angle (the angle the plane of the bifurcating network makes with the horizontal) is an important contributor to bubble splitting ratio at each bifurcation within the bifurcating network. When compared to corresponding constant flow, pulsatile flow was shown to produce insignificant changes to the overall splitting ratio of the bubble despite the order one Womersley numbers, suggesting that bubble splitting through the vasculature could be modeled adequately with a more modest constant flow model. However, bubble lodging was affected by the flow pulsatility, and the effects of pulsatile flow were evident in the dependence of splitting ratio of bubble length. The ability of bubbles to remain lodged after reaching a steady state in the bifurcations is promising for the effectiveness of gas embolotherapy to occlude blood flow to tumors, and indicates the importance of understanding where lodging will occur in air embolism. The ability to accurately predict the bubble dynamics in unsteady flow within a bifurcating network is demonstrated and suggests the potential for bubbles in microfluidics devices to encode information in both steady and unsteady aspects of their dynamics.

Local error estimates for adaptive simulation of the Reaction-Diffusion Master Equation via operator splitting.

PubMed

Hellander, Andreas; Lawson, Michael J; Drawert, Brian; Petzold, Linda

2014-06-01

The efficiency of exact simulation methods for the reaction-diffusion master equation (RDME) is severely limited by the large number of diffusion events if the mesh is fine or if diffusion constants are large. Furthermore, inherent properties of exact kinetic-Monte Carlo simulation methods limit the efficiency of parallel implementations. Several approximate and hybrid methods have appeared that enable more efficient simulation of the RDME. A common feature to most of them is that they rely on splitting the system into its reaction and diffusion parts and updating them sequentially over a discrete timestep. This use of operator splitting enables more efficient simulation but it comes at the price of a temporal discretization error that depends on the size of the timestep. So far, existing methods have not attempted to estimate or control this error in a systematic manner. This makes the solvers hard to use for practitioners since they must guess an appropriate timestep. It also makes the solvers potentially less efficient than if the timesteps are adapted to control the error. Here, we derive estimates of the local error and propose a strategy to adaptively select the timestep when the RDME is simulated via a first order operator splitting. While the strategy is general and applicable to a wide range of approximate and hybrid methods, we exemplify it here by extending a previously published approximate method, the Diffusive Finite-State Projection (DFSP) method, to incorporate temporal adaptivity.

Time series evaluation of an intervention to increase statin tablet splitting by general practitioners.

PubMed

Polinski, Jennifer M; Schneeweiss, Sebastian; Maclure, Malcolm; Marshall, Blair; Ramsden, Samuel; Dormuth, Colin

2011-02-01

Tablet splitting, in which a higher-dose tablet is split to get 2 doses, reduces patients' drug costs. Statins can be split safely. General practitioners (GPs) may not direct their patients to split statins because of safety concerns or unawareness of costs. Medical chart inserts provide cost-effective education to physicians. The aim of this study was to assess whether providing GPs with statin-splitting chart inserts would increase splitting rates, and to identify predictors of splitting. In 2005 and 2006, we faxed a statin chart insert to British Columbia GPs with a request for a telephone interview. Consenting GPs were mailed 3 statin chart inserts and interviewed by phone (the intervention). In an interrupted time series, we compared monthly rates of statin-splitting prescriptions among intervention and nonintervention GPs before, during, and after the intervention. In multivariate logistic regressions accounting for patient clustering, predictors of splitting included physician and patient demographics and the specific statin prescribed. Of 5051 GPs reached, 282 (6%) agreed to the intervention. Before the intervention, GPs' splitting rate was 2.6%; after intervention, GPs' splitting rate was 7.5%. The rate for the nonintervention GPs was 4.4%. Intervention GPs were 1.68 (95% CI, 1.12-2.53) times more likely to prescribe splitting after the intervention than were nonintervention GPs. Other predictors were a patient's female sex (odds ratio [OR] = 1.26; 95% CI, 1.18-1.34), lower patient income (OR = 1.33; 95% CI, 1.18-1.34), and a lack of drug insurance (OR = 1.89; 95% CI, 1.69-2.04). An inexpensive intervention was effective in producing a sustained increase in GPs' splitting rate during 22 months of observed follow-up. Expanding statin-splitting education to all GPs might reduce prescription costs for many patients and payors. Copyright © 2011 Elsevier HS Journals, Inc. All rights reserved.

Time series evaluation of an intervention to increase statin tablet splitting by general practitioners

PubMed Central

Polinski, Jennifer M.; Schneeweiss, Sebastian; Maclure, Malcolm; Marshall, Blair; Ramsden, Samuel; Dormuth, Colin

2011-01-01

Background Tablet splitting, in which a higher-dose tablet is split to get two doses, reduces patients’ drug costs. Statins can be split safely. General practitioners (GPs) may not direct their patients to split statins because of safety concerns or unawareness of costs. Medical chart inserts provide cost-effective education to physicians. We evaluated whether providing GPs with statin splitting chart inserts would increase splitting rates and identified predictors of splitting. Methods In 2005–2006, we faxed a statin chart insert to British Columbia GPs with a request for a telephone interview. Consenting GPs were mailed 3 statin chart inserts and interviewed by phone (the intervention). In an interrupted time series, we compared monthly rates of statin splitting prescriptions among intervention and non-intervention GPs before, during, and after the intervention. In multivariate logistic regressions accounting for patient clustering, predictors of splitting included physician and patient demographics and the specific statin prescribed. Results Of 5,051 GPs reached, 282 (6%) agreed to the intervention. Before the intervention, GPs’ splitting rate was 2.6%; after, intervention GPs’ splitting rate was 7.5%, non-intervention GPs’ was 4.4%. Intervention GPs were 1.68 (95% CI 1.12–2.53) times more likely to prescribe splitting after the intervention than were non-intervention GPs. Other predictors were a patient’s female sex (OR=1.26, 95% CI 1.18–1.34), lower patient income (OR=1.33, 95% CI 1.18–1.34), and no drug insurance (OR=1.89, 95% CI 1.69–2.04). Interpretation An inexpensive intervention was effective in producing a sustained increase in GPs’ splitting rate during 22 months of observed follow-up. Expanding statin splitting education to all GPs could reduce prescription costs for many patients and payors. PMID:21497707

Growth rate for blackhole instabilities

NASA Astrophysics Data System (ADS)

Prabhu, Kartik; Wald, Robert

2015-04-01

Hollands and Wald showed that dynamic stability of stationary axisymmetric black holes is equivalent to positivity of canonical energy on a space of linearised axisymmetric perturbations satisfying certain boundary and gauge conditions. Using a reflection isometry of the background, we split the energy into kinetic and potential parts. We show that the kinetic energy is positive. In the case that potential energy is negative, we show existence of exponentially growing perturbations and further obtain a variational formula for the growth rate.

Quantum phase transitions and phase diagram for a one-dimensional p-wave superconductor with an incommensurate potential.

PubMed

Cai, X

2014-04-16

The effect of the incommensurate potential is studied for the one-dimensional p-wave superconductor. It is determined by analyzing various properties, such as the superconducting gap, the long-range order of the correlation function, the inverse participation ratio and the Z2 topological invariant, etc. In particular, two important aspects of the effect are investigated: (1) as disorder, the incommensurate potential destroys the superconductivity and drives the system into the Anderson localized phase; (2) as a quasi-periodic potential, the incommensurate potential causes band splitting and turns the system with certain chemical potential into the band insulator phase. A full phase diagram is also presented in the chemical potential-incommensurate potential strength plane.

Generalized field-splitting algorithms for optimal IMRT delivery efficiency.

PubMed

Kamath, Srijit; Sahni, Sartaj; Li, Jonathan; Ranka, Sanjay; Palta, Jatinder

2007-09-21

Intensity-modulated radiation therapy (IMRT) uses radiation beams of varying intensities to deliver varying doses of radiation to different areas of the tissue. The use of IMRT has allowed the delivery of higher doses of radiation to the tumor and lower doses to the surrounding healthy tissue. It is not uncommon for head and neck tumors, for example, to have large treatment widths that are not deliverable using a single field. In such cases, the intensity matrix generated by the optimizer needs to be split into two or three matrices, each of which may be delivered using a single field. Existing field-splitting algorithms used the pre-specified arbitrary split line or region where the intensity matrix is split along a column, i.e., all rows of the matrix are split along the same column (with or without the overlapping of split fields, i.e., feathering). If three fields result, then the two splits are along the same two columns for all rows. In this paper we study the problem of splitting a large field into two or three subfields with the field width as the only constraint, allowing for an arbitrary overlap of the split fields, so that the total MU efficiency of delivering the split fields is maximized. Proof of optimality is provided for the proposed algorithm. An average decrease of 18.8% is found in the total MUs when compared to the split generated by a commercial treatment planning system and that of 10% is found in the total MUs when compared to the split generated by our previously published algorithm.

Clinical Comparison of At-Home and In-Office Dental Bleaching Procedures: A Randomized Trial of a Split-Mouth Design.

PubMed

Machado, Lucas Silveira; Anchieta, Rodolfo Bruniera; dos Santos, Paulo Henrique; Briso, André Luiz; Tovar, Nick; Janal, Malvin N; Coelho, Paulo Guilherme; Sundfeld, Renato Herman

2016-01-01

The objective of this split-mouth clinical study was to compare a combination of in-office and at-home dental bleaching with at-home bleaching alone. Two applications of in-office bleaching were performed, with one appointment per week, using 38% hydrogen peroxide. At-home bleaching was performed with or without in-office bleaching using 10% carbamide peroxide in a custom-made tray every night for 2 weeks. The factor studied was the bleaching technique on two levels: Technique 1 (in-office bleaching combined with home bleaching) and Technique 2 (home bleaching only). The response variables were color change, dental sensitivity, morphology, and surface roughness. The maxillary right and left hemiarches of the participants were submitted to in-office placebo treatment and in-office bleaching, respectively (Phase 1), and at-home bleaching (Phase 2) treatment was performed on both hemiarches, characterizing a split-mouth design. Enamel surface changes and roughness were analyzed with scanning electron microscopy and optical interferometry using epoxy replicas. No statistically significant differences were observed between the bleaching techniques for either the visual or the digital analyses. There was a significant difference in dental sensitivity when both dental bleaching techniques were used, with in-office bleaching producing the highest levels of dental sensitivity after the baseline. Microscopic analysis of the morphology and roughness of the enamel surface showed no significant changes between the bleaching techniques. The two techniques produced similar results in color change, and the combination technique produced the highest levels of sensitivity. Neither technique promoted changes in morphology or surface roughness of enamel.

Automated Photoreceptor Cell Identification on Nonconfocal Adaptive Optics Images Using Multiscale Circular Voting.

PubMed

Liu, Jianfei; Jung, HaeWon; Dubra, Alfredo; Tam, Johnny

2017-09-01

Adaptive optics scanning light ophthalmoscopy (AOSLO) has enabled quantification of the photoreceptor mosaic in the living human eye using metrics such as cell density and average spacing. These rely on the identification of individual cells. Here, we demonstrate a novel approach for computer-aided identification of cone photoreceptors on nonconfocal split detection AOSLO images. Algorithms for identification of cone photoreceptors were developed, based on multiscale circular voting (MSCV) in combination with a priori knowledge that split detection images resemble Nomarski differential interference contrast images, in which dark and bright regions are present on the two sides of each cell. The proposed algorithm locates dark and bright region pairs, iteratively refining the identification across multiple scales. Identification accuracy was assessed in data from 10 subjects by comparing automated identifications with manual labeling, followed by computation of density and spacing metrics for comparison to histology and published data. There was good agreement between manual and automated cone identifications with overall recall, precision, and F1 score of 92.9%, 90.8%, and 91.8%, respectively. On average, computed density and spacing values using automated identification were within 10.7% and 11.2% of the expected histology values across eccentricities ranging from 0.5 to 6.2 mm. There was no statistically significant difference between MSCV-based and histology-based density measurements (P = 0.96, Kolmogorov-Smirnov 2-sample test). MSCV can accurately detect cone photoreceptors on split detection images across a range of eccentricities, enabling quick, objective estimation of photoreceptor mosaic metrics, which will be important for future clinical trials utilizing adaptive optics.

Morphometric study of mandibular ramus related to sagittal ramus split osteotomy and osteosynthesis.

PubMed

Vinicius de Oliveira, Marcelo; de Moraes, Paulo Hemerson; Olate, Sergio; Alonso, Maria Beatriz C; Watanabe, Plauto Christopher Aranha; Haiter-Neto, Francisco; de Albergaria-Barbosa, José Ricardo

2012-09-01

The objective of this study was to quantify the cortical bone thickness of the mandibular ramus to determine conditions related to sagittal split ramus osteotomy and placement of screws. The patient sample comprised 44 subjects of ages ranging from 46 to 52 years (mean age, 49 years). The cone-beam computed tomography was performed and realized 3 cuts in the third molar area (section A), 5 mm posterior (section B), and 5 mm posterior to the latter (section C). Measurement in the cortical areas of the superior and inferior levels related to mandibular canal and measurement related to the total width of the mandible was executed. Intraclass correlation coefficient with P < 0.05 was used. The result showed that the buccal and lingual cortical zone did not present statistical differences, and the minor value was 1.5 mm for each one. There were no differences in the superior and inferior cortical bone, and the total width of the mandible was between 15.9 and 8.5 mm in the anterior area, between 17.4 and 12.8 mm in the middle area, and between 18 and 8.8 mm in the posterior area. The distance superiorly to the mandibular canal presented a minimal SD with a mean of 8.5 mm in the anterior region, 10.6 mm for the middle region, and 12.5 mm in the posterior region. In conclusion, the cortical thickness of the mandibular ramus in the adult population is particularly strong and offers a good anchorage for screw insertion in sagittal split ramus osteotomy.

The effect of kidney morcellation on operative time, incision complications, and postoperative analgesia after laparoscopic nephrectomy.

PubMed

Camargo, Affonso H; Rubenstein, Jonathan N; Ershoff, Brent D; Meng, Maxwell V; Kane, Christopher J; Stoller, Marshall L

2006-01-01

Compare the outcomes between kidney morcellation and two types of open specimen extraction incisions, several covariates need to be taken into consideration that have not yet been studied. We retrospectively reviewed 153 consecutive patients who underwent laparoscopic nephrectomy at our institution, 107 who underwent specimen morcellation and 46 with intact specimen removal, either those with connected port sites with a muscle-cutting incision and those with a remote, muscle-splitting incision. Operative time, postoperative analgesia requirements, and incisional complications were evaluated using univariate and multivariate analysis, comparing variables such as patient age, gender, body mass index (BMI), laterality, benign versus cancerous renal conditions, estimated blood loss, specimen weight, overall complications, and length of stay. There was no significant difference for operative time between the 2 treatment groups (p = 0.65). Incision related complications occurred in 2 patients (4.4%) from the intact specimen group but none in the morcellation group (p = 0.03). Overall narcotic requirement was lower in patients with morcellated (41 mg) compared to intact specimen retrieval (66 mg) on univariate (p = 0.03) and multivariate analysis (p = 0.049). Upon further stratification, however, there was no significant difference in mean narcotic requirement between the morcellation and muscle-splitting incision subgroup (p = 0.14). Morcellation does not extend operative time, and is associated with significantly less postoperative pain compared to intact specimen retrieval overall, although this is not statistically significant if a remote, muscle-splitting incision is made. Morcellation markedly reduces the risk of incisional-related complications.

Brain vascular image enhancement based on gradient adjust with split Bregman

NASA Astrophysics Data System (ADS)

Liang, Xiao; Dong, Di; Hui, Hui; Zhang, Liwen; Fang, Mengjie; Tian, Jie

2016-04-01

Light Sheet Microscopy is a high-resolution fluorescence microscopic technique which enables to observe the mouse brain vascular network clearly with immunostaining. However, micro-vessels are stained with few fluorescence antibodies and their signals are much weaker than large vessels, which make micro-vessels unclear in LSM images. In this work, we developed a vascular image enhancement method to enhance micro-vessel details which should be useful for vessel statistics analysis. Since gradient describes the edge information of the vessel, the main idea of our method is to increase the gradient values of the enhanced image to improve the micro-vessels contrast. Our method contained two steps: 1) calculate the gradient image of LSM image, and then amplify high gradient values of the original image to enhance the vessel edge and suppress low gradient values to remove noises. Then we formulated a new L1-norm regularization optimization problem to find an image with the expected gradient while keeping the main structure information of the original image. 2) The split Bregman iteration method was used to deal with the L1-norm regularization problem and generate the final enhanced image. The main advantage of the split Bregman method is that it has both fast convergence and low memory cost. In order to verify the effectiveness of our method, we applied our method to a series of mouse brain vascular images acquired from a commercial LSM system in our lab. The experimental results showed that our method could greatly enhance micro-vessel edges which were unclear in the original images.

The impact of epilepsy surgery on quality of life in children.

PubMed

Sabaz, M; Lawson, J A; Cairns, D R; Duchowny, M S; Resnick, T J; Dean, P M; Bleasel, A F; Bye, A M E

2006-02-28

To determine if epilepsy surgery is effective in improving the quality of life (QOL) of children with intractable seizures using the Quality of Life in Childhood Epilepsy Questionnaire (QOLCE). The authors conducted a prospective study of the families of 35 children with intractable epilepsy who underwent epilepsy surgery. Parents completed the QOLCE preoperatively and again 6 to 18 months after surgery. At both assessment dates parents indicated the severity of their child's seizures during the past 6 months and the frequency of their child's seizures during the past 4 weeks on Likert-type scales. Children were split into two groups according to surgery outcome: seizure free vs persistent seizures. Statistical analyses were conducted to determine if children rendered seizure free showed a greater improvement in QOL compared to those with persistent seizures postoperatively. Greater improvement in QOL was documented for children rendered seizure free vs children with persistent seizures. This was significant for the overall QOLCE QOL score and subscales assessing cognitive, social, emotional, behavioral, and physical domains of life. Epilepsy surgery improves the quality of life of children rendered seizure free. Families can be counseled preoperatively of the potential benefits of surgery beyond seizure reduction.

Bad split during bilateral sagittal split osteotomy of the mandible with separators: a retrospective study of 427 patients.

PubMed

Mensink, Gertjan; Verweij, Jop P; Frank, Michael D; Eelco Bergsma, J; Richard van Merkesteyn, J P

2013-09-01

An unfavourable fracture, known as a bad split, is a common operative complication in bilateral sagittal split osteotomy (BSSO). The reported incidence ranges from 0.5 to 5.5%/site. Since 1994 we have used sagittal splitters and separators instead of chisels for BSSO in our clinic in an attempt to prevent postoperative hypoaesthesia. Theoretically an increased percentage of bad splits could be expected with this technique. In this retrospective study we aimed to find out the incidence of bad splits associated with BSSO done with splitters and separators. We also assessed the risk factors for bad splits. The study group comprised 427 consecutive patients among whom the incidence of bad splits was 2.0%/site, which is well within the reported range. The only predictive factor for a bad split was the removal of third molars at the same time as BSSO. There was no significant association between bad splits and age, sex, class of occlusion, or the experience of the surgeon. We think that doing a BSSO with splitters and separators instead of chisels does not increase the risk of a bad split, and is therefore safe with predictable results. Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

SU-E-T-448: Heightened Apical Positivity of 2-Year Post-Radiotherapy Biopsies Is Not Related to Suboptimal Dosimetry

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

Studenski, M; Stoyanova, R; Abramowitz, M

2015-06-15

Purpose: Previous research has demonstrated that following radiation therapy for prostate cancer, there is a relative increase in positive biopsies in the apex versus the rest of the prostate. The increase could be due to: 1) Inter-fraction apex motion or deformation, 2) Intra-fraction apex motion or deformation, 3) Suboptimal dose coverage in the apex, 4) Tissue composition in the apex and/or 5) Prostate size. In this initial study, the potential for suboptimal dose coverage in the apex was assessed by splitting the prostate planning target volume into the apex (inferior third) and remainder. Methods: 69 patients were selected from 303more » patients treated on a clinical radiotherapy trial for prostate cancer. These patients were selected as they had both a localized (sextant template) 2-year post-treatment biopsy and 3D dose information. Of these patients, 10 had positive biopsies in the apex, 8 in the remainder and 11 in both locations. For all patients, the following dosimetric data was acquired from the apex dose volume histogram: Dmean, Dmax, Dmin, D95% and V100%. Unpaired, one-tailed t-tests were used to test for statistical significance (p < 0.05) between all dosimetric parameters for patients with positive versus negative apical biopsies. Additionally, D95% for the apex was plotted against D95% of the remainder. Results: There was no statistical difference for the selected apical dosimetric parameters for patients with positive versus negative biopsies (p-values > 0.05). No correlation was found between D95% (normalized to the prescription dose) for the apex and remainder (R{sup 2} = 0.0116). Conclusion: No correlation was found between positive apical biopsy and suboptimal dosimetric coverage. Current research is looking into inter-fraction apex motion and deformation as a potential source of the increased apical failure using daily CBCT images.« less

Paired-pulse flash-visual evoked potentials: new methods revive an old test.

PubMed

Cantello, Roberto; Strigaro, Gionata; Prandi, Paolo; Varrasi, Claudia; Mula, Marco; Monaco, Francesco

2011-08-01

We aimed at reviving with modern technology the paired flash-visual evoked potential (F-VEP) testing of the visual system excitability. In the 1960s, methodological problems hindered this test, which was expected to provide important physiologic information. We studied 22 consenting healthy subjects (10 men). We recorded F-VEPs from electrodes over occipital and central brain regions. We delivered single flashes, mixed at random to flash pairs at the interstimulus interval (ISI) of 333, 125, 62.5, 50, 33, and 16.5 ms, (i.e. an internal frequency (IF) of 3, 8, 16, 20, 30, and 60 Hz). Recordings were performed with the subject's eyes closed and opened. The F-VEP was split into a "main complex" and an "afterdischarge", which we analyzed statistically in relation to the eye state (closed or open) and to the changes due to paired stimulation. The eye state affected the single F-VEP size, latency and shape significantly (p<0.05). On paired stimulation, the test (second) F-VEP exhibited significant (p<0.05), ISI-dependent size changes, such as a progressive decrease for ISIs from 62.5 to 16.5 ms (IFs of 16-60 Hz), whose timing/amount varied significantly (p<0.05) according to the eye state and to the F-VEP epoch considered. Suppression of the test F-VEP was never complete, even for the shortest ISI (ISI=16.5 ms, IF=60 Hz). The eye state (closed or open) must be considered meticulously when studying F-VEPs. F-VEP changes on paired stimulation express neural inhibition within the visual system, which can be depicted as ISI-dependent curves. Modern equipment and simplified measures render this an easy test, with statistical validity, providing specific information on the excitability properties of the visual system. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Completing the Results of the 2013 Boston Marathon

PubMed Central

Hammerling, Dorit; Cefalu, Matthew; Cisewski, Jessi; Dominici, Francesca; Parmigiani, Giovanni; Paulson, Charles; Smith, Richard L.

2014-01-01

The 2013 Boston marathon was disrupted by two bombs placed near the finish line. The bombs resulted in three deaths and several hundred injuries. Of lesser concern, in the immediate aftermath, was the fact that nearly 6,000 runners failed to finish the race. We were approached by the marathon's organizers, the Boston Athletic Association (BAA), and asked to recommend a procedure for projecting finish times for the runners who could not complete the race. With assistance from the BAA, we created a dataset consisting of all the runners in the 2013 race who reached the halfway point but failed to finish, as well as all runners from the 2010 and 2011 Boston marathons. The data consist of split times from each of the 5 km sections of the course, as well as the final 2.2 km (from 40 km to the finish). The statistical objective is to predict the missing split times for the runners who failed to finish in 2013. We set this problem in the context of the matrix completion problem, examples of which include imputing missing data in DNA microarray experiments, and the Netflix prize problem. We propose five prediction methods and create a validation dataset to measure their performance by mean squared error and other measures. The best method used local regression based on a K-nearest-neighbors algorithm (KNN method), though several other methods produced results of similar quality. We show how the results were used to create projected times for the 2013 runners and discuss potential for future application of the same methodology. We present the whole project as an example of reproducible research, in that we are able to make the full data and all the algorithms we have used publicly available, which may facilitate future research extending the methods or proposing completely different approaches. PMID:24727904

Completing the results of the 2013 Boston marathon.

PubMed

Hammerling, Dorit; Cefalu, Matthew; Cisewski, Jessi; Dominici, Francesca; Parmigiani, Giovanni; Paulson, Charles; Smith, Richard L

2014-01-01

The 2013 Boston marathon was disrupted by two bombs placed near the finish line. The bombs resulted in three deaths and several hundred injuries. Of lesser concern, in the immediate aftermath, was the fact that nearly 6,000 runners failed to finish the race. We were approached by the marathon's organizers, the Boston Athletic Association (BAA), and asked to recommend a procedure for projecting finish times for the runners who could not complete the race. With assistance from the BAA, we created a dataset consisting of all the runners in the 2013 race who reached the halfway point but failed to finish, as well as all runners from the 2010 and 2011 Boston marathons. The data consist of split times from each of the 5 km sections of the course, as well as the final 2.2 km (from 40 km to the finish). The statistical objective is to predict the missing split times for the runners who failed to finish in 2013. We set this problem in the context of the matrix completion problem, examples of which include imputing missing data in DNA microarray experiments, and the Netflix prize problem. We propose five prediction methods and create a validation dataset to measure their performance by mean squared error and other measures. The best method used local regression based on a K-nearest-neighbors algorithm (KNN method), though several other methods produced results of similar quality. We show how the results were used to create projected times for the 2013 runners and discuss potential for future application of the same methodology. We present the whole project as an example of reproducible research, in that we are able to make the full data and all the algorithms we have used publicly available, which may facilitate future research extending the methods or proposing completely different approaches.

Improved Fast Centralized Retransmission Scheme for High-Layer Functional Split in 5G Network

NASA Astrophysics Data System (ADS)

Xu, Sen; Hou, Meng; Fu, Yu; Bian, Honglian; Gao, Cheng

2018-01-01

In order to satisfy the varied 5G critical requirements and the virtualization of the RAN hardware, a two-level architecture for 5G RAN has been studied in 3GPP 5G SI stage. The performance of the PDCP-RLC split option and intra-RLC split option, two mainly concerned options for high layer functional split, exist an ongoing debate. This paper firstly gives an overview of CU-DU split study work in 3GPP. By the comparison of implementation complexity, the standardization impact and system performance, our evaluation result shows the PDCP-RLC split Option outperforms the intra-RLC split option. Aiming to how to reduce the retransmission delay during the intra-CU inter-DU handover, the mainly drawback of PDCP-RLC split option, this paper proposes an improved fast centralized retransmission solution with a low implementation complexity. Finally, system level simulations show that the PDCP-RLC split option with the proposed scheme can significantly improve the UE’s experience.

Studies of thermochemical water-splitting cycles

NASA Technical Reports Server (NTRS)

Remick, R. J.; Foh, S. E.

1980-01-01

Higher temperatures and more isothermal heat profiles of solar heat sources are developed. The metal oxide metal sulfate class of cycles were suited for solar heat sources. Electrochemical oxidation of SO2 and thermochemical reactions are presented. Electrolytic oxidation of sulfur dioxide in dilute sulfuric acid solutions were appropriate for metal oxide metal sulfate cycles. The cell voltage at workable current densities required for the oxidation of SO2 was critical to the efficient operation of any metal oxide metal sulfate cycle. A sulfur dioxide depolarized electrolysis cell for the splitting of water via optimization of the anode reaction is discussed. Sulfuric acid concentrations of 30 to 35 weight percent are preferred. Platinized platinum or smooth platinum gave the best anode kinetics at a given potential of the five materials examined.

Direct observation of strain-induced orbital valence band splitting in HfSe2 by sodium intercalation

NASA Astrophysics Data System (ADS)

Eknapakul, T.; Fongkaew, I.; Siriroj, S.; Jindata, W.; Chaiyachad, S.; Mo, S.-K.; Thakur, S.; Petaccia, L.; Takagi, H.; Limpijumnong, S.; Meevasana, W.

2018-05-01

By using angle-resolved photoemission spectroscopy (ARPES), the variation of the electronic structure of HfSe2 has been studied as a function of sodium intercalation. We observe how this drives a band splitting of the p -orbital valence bands and a simultaneous reduction of the indirect band gap by values of up to 400 and 280 meV, respectively. Our calculations indicate that such behavior is driven by the band deformation potential, which is a result of our observed strain induced by sodium intercalation. The applied uniaxial strain calculations based on density functional theory agree strongly with the experimental ARPES data. These findings should assist in studying the physical relationship between intercalation and strain, as well as for large-scale two-dimensional straintronics.

Broad-spectrum enhanced absorption of graphene-molybdenum disulfide photovoltaic cells in metal-mirror microcavity.

PubMed

Jiang-Tao, Liu; Yun-Kai, Cao; Hong, Tong; Dai-Qiang, Wang; Zhen-Hua, Wu

2018-04-06

The optical absorption of graphene-molybdenum disulfide photovoltaic cells (GM-PVc) in wedge-shaped metal-mirror microcavities (w-MMCs) combined with a spectrum-splitting structure was studied. Results showed that the combination of spectrum-splitting structure and w-MMC can enable the light absorption of GM-PVcs to reach about 65% in the broad spectrum. The influence of processing errors on the absorption of GM-PVcs in w-MMCs was 3-14 times lower than that of GM-PVcs in wedge photonic crystal microcavities. The light absorption of GM-PVcs reached 60% in the broad spectrum, even with the processing errors. The proposed structure is easy to implement and may have potentially important applications in the development of ultra-thin and high-efficiency solar cells and optoelectronic devices.

Broad-spectrum enhanced absorption of graphene-molybdenum disulfide photovoltaic cells in metal-mirror microcavity

NASA Astrophysics Data System (ADS)

Jiang-Tao, Liu; Yun-Kai, Cao; Hong, Tong; Dai-Qiang, Wang; Zhen-Hua, Wu

2018-04-01

The optical absorption of graphene-molybdenum disulfide photovoltaic cells (GM-PVc) in wedge-shaped metal-mirror microcavities (w-MMCs) combined with a spectrum-splitting structure was studied. Results showed that the combination of spectrum-splitting structure and w-MMC can enable the light absorption of GM-PVcs to reach about 65% in the broad spectrum. The influence of processing errors on the absorption of GM-PVcs in w-MMCs was 3-14 times lower than that of GM-PVcs in wedge photonic crystal microcavities. The light absorption of GM-PVcs reached 60% in the broad spectrum, even with the processing errors. The proposed structure is easy to implement and may have potentially important applications in the development of ultra-thin and high-efficiency solar cells and optoelectronic devices.

Hyperspherical nuclear motion of H3 + and D3 + in the electronic triplet state, a 3Sigmau +.

PubMed

Ferreira, Tiago Mendes; Alijah, Alexander; Varandas, António J C

2008-02-07

The potential energy surface of H(3) (+) in the lowest electronic triplet state, a (3)Sigma(u) (+), shows three equivalent minima at linear nuclear configurations. The vibrational levels of H(3) (+) and D(3) (+) on this surface can therefore be described as superimposed linear molecule states. Owing to such a superposition, each vibrational state characterized by quantum numbers of an isolated linear molecule obtains a one- and a two-dimensional component. The energy splittings between the two components have now been rationalized within a hyperspherical picture. It is shown that nuclear motion along the hyperangle phi mainly accounts for the splittings and provides upper bounds. This hyperspherical motion can be considered an extension of the antisymmetric stretching motion of the individual linear molecule.

Local D3/D7 μ-SPLIT SUSY, 125 GeV Higgs and Large Volume Ricci-Flat Swiss-Cheese Metrics:. a Brief Review

NASA Astrophysics Data System (ADS)

Misra, Aalok

In this paper, we review briefly recent progress made in realizing local(ized around a mobile spacetime filling D3-brane in) D3/D7 μ-split Supersymmetry in (the large volume limit of Type IIB) String Theory (compactified on Swiss-Cheese Calabi-Yau orientifolds) as well as obtaining a 125 GeV (light) Higgs in the same setup. We also discuss obtaining the geometric Kähler potential (and hence the Ricci-flat metric) for the Swiss-Cheese Calabi-Yau in the large volume limit using the Donaldson's algorithm and intuition from GLSM-based calculations — we present new results for Swiss-Cheese Calabi-Yau (used in the setup) metrics at points finitely away from the "big" divisor.

Electrochemically hydrogenated TiO2 nanotubes with improved photoelectrochemical water splitting performance

PubMed Central

2013-01-01

One-dimensional anodic titanium oxide (ATO) nanotube arrays hold great potential as photoanode for photoelectrochemical (PEC) water splitting. In this work, we report a facile and eco-friendly electrochemical hydrogenation method to modify the electronic and PEC properties of ATO nanotube films. The hydrogenated ATO (ATO-H) electrodes present a significantly improved photocurrent of 0.65 mA/cm2 in comparison with that of pristine ATO nanotubes (0.29 mA/cm2) recorded under air mass 1.5 global illumination. The incident photon-to-current efficiency measurement suggests that the enhanced photocurrent of ATO-H nanotubes is mainly ascribed to the improved photoactivity in the UV region. We propose that the electrochemical hydrogenation induced surface oxygen vacancies contribute to the substantially enhanced electrical conductivity and photoactivity. PMID:24047205

Double-clad photonic crystal fiber coupler for compact nonlinear optical microscopy imaging.

PubMed

Fu, Ling; Gu, Min

2006-05-15

A 1 x 2 double-clad photonic crystal fiber coupler is fabricated by the fused tapered method, showing a low excess loss of 1.1 dB and a splitting ratio of 97/3 over the entire visible and near-infrared wavelength range. In addition to the property of splitting the laser power, the double-clad feature of the coupler facilitates the separation of a near-infrared single-mode beam from a visible multimode beam, which is ideal for nonlinear optical microscopy imaging. In conjunction with a gradient-index lens, this coupler is used to construct a miniaturized microscope based on two-photon fluorescence and second-harmonic generation. Three-dimensional nonlinear optical images demonstrate potential applications of the coupler to compact all-fiber and nonlinear optical microscopy and endoscopy.

Novel failure mechanism and improvement for split-gate trench MOSFET with large current under unclamped inductive switch stress

NASA Astrophysics Data System (ADS)

Tian, Ye; Yang, Zhuo; Xu, Zhiyuan; Liu, Siyang; Sun, Weifeng; Shi, Longxing; Zhu, Yuanzheng; Ye, Peng; Zhou, Jincheng

2018-04-01

In this paper, a novel failure mechanism under unclamped inductive switch (UIS) for Split-Gate Trench Metal Oxide Semiconductor Field Effect Transistor (MOSFET) with large current is investigated. The device sample is tested and analyzed in detail. The simulation results demonstrate that the nonuniform potential distribution of the source poly should be responsible for the failure. Three structures are proposed and verified available to improve the device UIS ruggedness by TCAD simulation. The best one of the structures the device with source metal inserting into source poly through contacts in the field oxide is carried out and measured. The results demonstrate that the optimized structure can balance the trade-off between the UIS ruggedness and the static characteristics.

Calculation of the vibrational excited states of malonaldehyde and their tunneling splittings with the multi-configuration time-dependent Hartree method

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

Schröder, Markus, E-mail: Markus.Schroeder@pci.uni-heidelberg.de; Meyer, Hans-Dieter, E-mail: Hans-Dieter.Meyer@pci.uni-heidelberg.de

2014-07-21

We report energies and tunneling splittings of vibrational excited states of malonaldehyde which have been obtained using full dimensional quantum mechanical calculations. To this end we employed the multi configuration time-dependent Hartree method. The results have been obtained using a recently published potential energy surface [Y. Wang, B. J. Braams, J. M. Bowman, S. Carter, and D. P. Tew, J. Chem. Phys. 128, 224314 (2008)] which has been brought into a suitable form by a modified version of the n-mode representation which was used with two different arrangements of coordinates. The relevant terms of the expansion have been identified withmore » a Metropolis algorithm and a diffusion Monte-Carlo technique, respectively.« less

Processing Flexible Form-to-Meaning Mappings: Evidence for Enriched Composition as Opposed to Indeterminacy

ERIC Educational Resources Information Center

Roehm, Dietmar; Sorace, Antonella; Bornkessel-Schlesewsky, Ina

2013-01-01

Sometimes, the relationship between form and meaning in language is not one-to-one. Here, we used event-related brain potentials (ERPs) to illuminate the neural correlates of such flexible syntax-semantics mappings during sentence comprehension by examining split-intransitivity. While some ("rigid") verbs consistently select one…

Split Personality: Assessing the Potential for Organizational Identity in Reinforcing U.S. Military Jointness

DTIC Science & Technology

2015-07-17

company name’ ( logo ) ‘parent company name’ ( logo ) ‘business unit name’ ‘parent company name’ ( logo ) ‘specialization’ Example Barings Barings...26 in times of war when it seemed apparent that force goals would not be met. Most useful, however, is his recognition of an overall pattern of

Moving and adaptive grid methods for compressible flows

NASA Technical Reports Server (NTRS)

Trepanier, Jean-Yves; Camarero, Ricardo

1995-01-01

This paper describes adaptive grid methods developed specifically for compressible flow computations. The basic flow solver is a finite-volume implementation of Roe's flux difference splitting scheme or arbitrarily moving unstructured triangular meshes. The grid adaptation is performed according to geometric and flow requirements. Some results are included to illustrate the potential of the methodology.

Serial DNA relay in DNA logic gates by electrical fusion and mechanical splitting of droplets

PubMed Central

Kawano, Ryuji; Takinoue, Masahiro; Osaki, Toshihisa; Kamiya, Koki; Miki, Norihisa

2017-01-01

DNA logic circuits utilizing DNA hybridization and/or enzymatic reactions have drawn increasing attention for their potential applications in the diagnosis and treatment of cellular diseases. The compartmentalization of such a system into a microdroplet considerably helps to precisely regulate local interactions and reactions between molecules. In this study, we introduced a relay approach for enabling the transfer of DNA from one droplet to another to implement multi-step sequential logic operations. We proposed electrical fusion and mechanical splitting of droplets to facilitate the DNA flow at the inputs, logic operation, output, and serial connection between two logic gates. We developed Negative-OR operations integrated by a serial connection of the OR gate and NOT gate incorporated in a series of droplets. The four types of input defined by the presence/absence of DNA in the input droplet pair were correctly reflected in the readout at the Negative-OR gate. The proposed approach potentially allows for serial and parallel logic operations that could be used for complex diagnostic applications. PMID:28700641

Criteria for disintegration of an uncharged conducting liquid jet in a transverse electric field

NASA Astrophysics Data System (ADS)

Zubareva, O. V.; Zubarev, N. M.; Volkov, N. B.

2018-01-01

An uncharged conducting liquid cylindrical column (a jet for applications) placed between a pair of flat electrodes is considered. In the trivial case, when the electric field is absent, the jet with circular cross-section is the only possible equilibrium configuration of the system. In the presence of a potential difference between the electrodes, the jet is deformed by the electrostatic forces: its cross-section stretches along the electric field lines. In the case of the mutual compensation of the electrostatic and capillary forces, a new equilibrium configuration of the jet can appear. In a sufficiently strong field, the balance of the forces becomes impossible, and the jet disintegrates (splits into two separate jets). In the present work, we find the range of the parameters (the applied potential difference and the interelectrode distance), where the problem of finding the equilibrium configurations of the jet has solutions. Also we obtain the conditions under which the solutions do not exist and, consequently, the jet splits. The results are compared with the previously studied limiting case of infinite interelectrode distance.

A Robust and Fast Method to Compute Shallow States without Adjustable Parameters: Simulations for a Silicon-Based Qubit

NASA Astrophysics Data System (ADS)

Debernardi, Alberto; Fanciulli, Marco

Within the framework of the envelope function approximation we have computed - without adjustable parameters and with a reduced computational effort due to analytical expression of relevant Hamiltonian terms - the energy levels of the shallow P impurity in silicon and the hyperfine and superhyperfine splitting of the ground state. We have studied the dependence of these quantities on the applied external electric field along the [001] direction. Our results reproduce correctly the experimental splitting of the impurity ground states detected at zero electric field and provide reliable predictions for values of the field where experimental data are lacking. Further, we have studied the effect of confinement of a shallow state of a P atom at the center of a spherical Si-nanocrystal embedded in a SiO2 matrix. In our simulations the valley-orbit interaction of a realistically screened Coulomb potential and of the core potential are included exactly, within the numerical accuracy due to the use of a finite basis set, while band-anisotropy effects are taken into account within the effective-mass approximation.

Microwave energy harvesting based on metamaterial absorbers with multi-layered square split rings for wireless communications

NASA Astrophysics Data System (ADS)

Karaaslan, Muharrem; Bağmancı, Mehmet; Ünal, Emin; Akgol, Oguzhan; Sabah, Cumali

2017-06-01

We propose the design of a multiband absorber based on multi-layered square split ring (MSSR) structure. The multi-layered metamaterial structure is designed to be used in the frequency bands such as WIMAX, WLAN and satellite communication region. The absorption levels of the proposed structure are higher than 90% for all resonance frequencies. In addition, the incident angle and polarization dependence of the multi-layered metamaterial absorber and harvester is also investigated and it is observed that the structure has polarization angle independent frequency response with good absorption characteristics in the entire working frequency band. The energy harvesting ratios of the structure is investigated especially for the resonance frequencies at which the maximum absorption occurs. The energy harvesting potential of the proposed MSSRs is as good as those of the structures given in the literature. Therefore, the suggested design having good absorption, polarization and angle independent characteristics with a wide bandwidth is a potential candidate for future energy harvesting applications in commonly used wireless communication bands, namely WIMAX, WLAN and satellite communication bands.

Nanofat grafting under a split-thickness skin graft for problematic wound management.

PubMed

Kemaloğlu, Cemal Alper

2016-01-01

Obesity and certain medical disorders make the reconstruction of skin defects challenging. Different kind of procedure can be used for these defect, besides, skin grafting is one of the most common and simplest procedure. Fat grafting and stem cells which are located in the adipose tissue have been commonly used in plastic surgery for regeneration and rejuvenation purposes. To decrease graft failure rate we performed nanofat grafting under an autologous split-thickness skin graft in our patient who had a problematic wound. The case of a 35-year-old female patient with a traumatic skin defect on her left anterior crural region is described herein. After subsequent flap reconstruction, the result was disappointing and the defect size was widened. The defect was treated with combined grafting (nanofat grafting under an autologous split-thickness skin graft). At the 6 months follow-up assessment after combined grafting, the integrity of the skin graft was good with excellent pliability. Combined grafting for problematic wounds seems to be a useful technique for cases requiring reconstruction. The potential existence of stem cells may be responsible for the successful result in our patient.

A Split-Luciferase-Based Trimer Formation Assay as a High-throughput Screening Platform for Therapeutics in Alport Syndrome.

PubMed

Omachi, Kohei; Kamura, Misato; Teramoto, Keisuke; Kojima, Haruka; Yokota, Tsubasa; Kaseda, Shota; Kuwazuru, Jun; Fukuda, Ryosuke; Koyama, Kosuke; Matsuyama, Shingo; Motomura, Keishi; Shuto, Tsuyoshi; Suico, Mary Ann; Kai, Hirofumi

2018-05-17

Alport syndrome is a hereditary glomerular disease caused by mutation in type IV collagen α3-α5 chains (α3-α5(IV)), which disrupts trimerization, leading to glomerular basement membrane degeneration. Correcting the trimerization of α3/α4/α5 chain is a feasible therapeutic approach, but is hindered by lack of information on the regulation of intracellular α(IV) chain and the absence of high-throughput screening (HTS) platforms to assess α345(IV) trimer formation. Here, we developed sets of split NanoLuc-fusion α345(IV) proteins to monitor α345(IV) trimerization of wild-type and clinically associated mutant α5(IV). The α345(IV) trimer assay, which satisfied the acceptance criteria for HTS, enabled the characterization of intracellular- and secretion-dependent defects of mutant α5(IV). Small interfering RNA-based and chemical screening targeting the ER identified several chemical chaperones that have potential to promote α345(IV) trimer formation. This split luciferase-based trimer formation assay is a functional HTS platform that realizes the feasibility of targeting α345(IV) trimers to treat Alport syndrome. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nanosheet Supported Single-Metal Atom Bifunctional Catalyst for Overall Water Splitting.

PubMed

Ling, Chongyi; Shi, Li; Ouyang, Yixin; Zeng, Xiao Cheng; Wang, Jinlan

2017-08-09

Nanosheet supported single-atom catalysts (SACs) can make full use of metal atoms and yet entail high selectivity and activity, and bifunctional catalysts can enable higher performance while lowering the cost than two separate unifunctional catalysts. Supported single-atom bifunctional catalysts are therefore of great economic interest and scientific importance. Here, on the basis of first-principles computations, we report a design of the first single-atom bifunctional eletrocatalyst, namely, isolated nickel atom supported on β 12 boron monolayer (Ni 1 /β 12 -BM), to achieve overall water splitting. This nanosheet supported SAC exhibits remarkable electrocatalytic performance with the computed overpotential for oxygen/hydrogen evolution reaction being just 0.40/0.06 V. The ab initio molecular dynamics simulation shows that the SAC can survive up to 800 K elevated temperature, while enacting a high energy barrier of 1.68 eV to prevent isolated Ni atoms from clustering. A viable experimental route for the synthesis of Ni 1 /β 12 -BM SAC is demonstrated from computer simulation. The desired nanosheet supported single-atom bifunctional catalysts not only show great potential for achieving overall water splitting but also offer cost-effective opportunities for advancing clean energy technology.

Two-wave photon Doppler velocimetry measurements in direct impact Hopkinson pressure bar experiments

NASA Astrophysics Data System (ADS)

Lea, Lewis J.; Jardine, Andrew P.

2015-09-01

Direct impact Hopkinson pressure bar systems offer many potential advantages over split Hopkinson pressure bars, including access to higher strain rates, higher strains for equivalent striker velocity and system length, lower dispersion and faster achievement of force equilibrium. Currently advantages are gained at a significant cost: the fact that input bar data is unavailable removes all information about the striker impacted specimen face, preventing the determination of force equilibrium, and requiring approximations to be made on the sample deformation history. Recently photon Doppler velocimetry methods have been developed, which can replace strain gauges on Hopkinson bars. In this paper we discuss an experimental method and complementary data analysis for using Doppler velocimetry to measure surface velocities of the striker and output bars in a direct impact bar experiment, allowing similar data to be recorded as in a split bar system, with the same level of convenience. We discuss extracting velocity and force measurements, and improving the accuracy and convenience of Doppler velocimetry on Hopkinson bars. Results obtained using the technique are compared to equivalent split bar tests, showing improved stress measurements for the lowest and highest strains.

Actual and Idealized Crystal Field Parameterizations for the Uranium Ions in UF 4

NASA Astrophysics Data System (ADS)

Gajek, Z.; Mulak, J.; Krupa, J. C.

1993-12-01

The crystal field parameters for the actual coordination symmetries of the uranium ions in UF 4, C2 and C1, and for their idealizations to D2, C2 v , D4, D4 d , and the Archimedean antiprism point symmetries are given. They have been calculated by means of both the perturbative ab initio model and the angular overlap model and are referenced to the recent results fitted by Carnall's group. The equivalency of some different sets of parameters has been verified with the standardization procedure. The adequacy of several idealized approaches has been tested by comparison of the corresponding splitting patterns of the 3H 4 ground state. Our results support the parameterization given by Carnall. Furthermore, the parameterization of the crystal field potential and the splitting diagram for the symmetryless uranium ion U( C1) are given. Having at our disposal the crystal field splittings for the two kinds of uranium ions in UF 4, U( C2) and U( C1), we calculate the model plots of the paramagnetic susceptibility χ( T) and the magnetic entropy associated with the Schottky anomaly Δ S( T) for UF 4.

Density Functional Theory Simulations of Water Adsorption and Activation on the (-201) β-Ga2 O3 Surface.

PubMed

Anvari, Roozbeh; Spagnoli, Dino; Parish, Giacinta; Nener, Brett

2018-03-09

Density functional theory calculations are used to study the molecular and dissociative adsorption of water on the (-201) β-Ga 2 O 3 surface. The effect of adsorption of different water-like species on the geometry, binding energies, vibrational spectra and the electronic structure of the surface are discussed. The study shows that although the hydrogen evolution reaction requires a small amount of energy to become energetically favourable, the over potential for activating the oxygen evolution reaction is quite high. The results of our calculations provide insight as to why a high voltage is required in experiments to activate the water-splitting reaction, whereas previous studies of gallium oxide predicted very low activation energies for other energetically more favourable facets. Application of this work to studies of GaN-based chemical sensors with gallium oxide surfaces shows that it is possible to select the gate bias so that the sensors are not influenced by water-splitting reactions. It was also found that in the region where water splitting does not occur, the surface can exist in two states, that is, water or hydroxyl terminated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of time of placement of investments for burnout and the type of rings being used on the casting accuracy.

PubMed

Shah, Shabir A; Naqash, Talib Amin; Padmanabhan, T V; Subramanium; Lambodaran; Nazir, Shazana

2014-03-01

The sole objective of casting procedure is to provide a metallic duplication of missing tooth structure, with as great accuracy as possible. The ability to produce well fitting castings require strict adherence to certain fundamentals. A study was undertaken to comparatively evaluate the effect on casting accuracy by subjecting the invested wax patterns to burnout after different time intervals. The effect on casting accuracy using metal ring into a pre heated burnout furnace and using split ring was also carried. The readings obtained were tabulated and subjected to statistical analysis.

The CLASSY clustering algorithm: Description, evaluation, and comparison with the iterative self-organizing clustering system (ISOCLS). [used for LACIE data

NASA Technical Reports Server (NTRS)

Lennington, R. K.; Malek, H.

1978-01-01

A clustering method, CLASSY, was developed, which alternates maximum likelihood iteration with a procedure for splitting, combining, and eliminating the resulting statistics. The method maximizes the fit of a mixture of normal distributions to the observed first through fourth central moments of the data and produces an estimate of the proportions, means, and covariances in this mixture. The mathematical model which is the basic for CLASSY and the actual operation of the algorithm is described. Data comparing the performances of CLASSY and ISOCLS on simulated and actual LACIE data are presented.

Evidence of variable bacterial colonization on coloured elastomeric ligatures during orthodontic treatment: An intermodular comparative study.

PubMed

Sharma, Ravish; Sharma, Kavita; Sawhney, Rajesh

2018-03-01

Besides, other factors, the choice of materials used as orthodontic ligatures could be one of the many tools to counter the effects of microbial adhesion, that culminates into dental ailments. Therefore, we assessed bacterial adhesion on elastomeric ligatures with special reference to coloured elastomeric rings during orthodontic treatment. A split mouth study, involving 240 samples of different elastomeric ligatures from forty orthodontic patients possessing good oral hygiene was carried out. The archwire was ligated to the brackets on both arches with elastomeric rings (superslick, clear transparent , blue and pink) at predetermined quadrants. After six weeks, ligatures from second premolars were removed and processed for bacterial enumeration using standard techniques. Bacterial counts were also determined for stimulated saliva samples taken at 0 and 6 weeks. A statistically significant difference in bacterial counts was obtained amongst different elastomeric modules used. Maximum bacterial counts were found on conventional pigmented elastomeric modules, followed by Superslick module and clear module. More number of bacteria associated with the conventional pink as compared to the conventional blue pigmented modules, however it was not statistically significant. The three bacterial genera Streptococcus Staphylococcus and Aerobic Lactobacilli adhered to elastomeric modules in following predominant pattern i.e. Conventional pink>Conventional Blue>Superslick>Clear. The studies evidenced colour and material dependent bacterial colonization on orthodontic modules and could be an indicator of bacterial biofilm forming potential based on surface chemistries and a clinically efficacious tool to redesign conventional and modified elastomeric rings as orthodontic ligation accessories. Key words: Bacterial colonization, biofilm, coloured elastomers, orthodontic ligatures.

A New Structure-Activity Relationship (SAR) Model for Predicting Drug-Induced Liver Injury, Based on Statistical and Expert-Based Structural Alerts

PubMed Central

Pizzo, Fabiola; Lombardo, Anna; Manganaro, Alberto; Benfenati, Emilio

2016-01-01

The prompt identification of chemical molecules with potential effects on liver may help in drug discovery and in raising the levels of protection for human health. Besides in vitro approaches, computational methods in toxicology are drawing attention. We built a structure-activity relationship (SAR) model for evaluating hepatotoxicity. After compiling a data set of 950 compounds using data from the literature, we randomly split it into training (80%) and test sets (20%). We also compiled an external validation set (101 compounds) for evaluating the performance of the model. To extract structural alerts (SAs) related to hepatotoxicity and non-hepatotoxicity we used SARpy, a statistical application that automatically identifies and extracts chemical fragments related to a specific activity. We also applied the chemical grouping approach for manually identifying other SAs. We calculated accuracy, specificity, sensitivity and Matthews correlation coefficient (MCC) on the training, test and external validation sets. Considering the complexity of the endpoint, the model performed well. In the training, test and external validation sets the accuracy was respectively 81, 63, and 68%, specificity 89, 33, and 33%, sensitivity 93, 88, and 80% and MCC 0.63, 0.27, and 0.13. Since it is preferable to overestimate hepatotoxicity rather than not to recognize unsafe compounds, the model's architecture followed a conservative approach. As it was built using human data, it might be applied without any need for extrapolation from other species. This model will be freely available in the VEGA platform. PMID:27920722

Comparison of two different forms of varnishes in the treatment of dentine hypersensitivity: a subject-blind randomised clinical study.

PubMed

Sethna, Gulnar Dara; Prabhuji, M L V; Karthikeyan, B V

2011-01-01

Dentine hypersensitivity is one of the most frequently recorded complaints of dental discomfort. Current evidence implicates patent dentinal tubules in hypersensitive dentine, and it follows that one effective way to reduce dentine sensitivity is to occlude the dentinal tubules. The purpose of this study was to compare the efficacy of two different desensitising agents, Cervitec varnish and Gluma varnish. Two hundred fifty patients self-reporting dentine hypersensitivity completed the paired split mouth randomised, subject-blind study. Each participant had a minimum of two sensitive teeth in at least two different quadrants and displaying a response of ≥3 cm to an evaporative stimulus. The hypersensitivity levels were measured with a tactile stimulus (scratchometer), thermal stimulus (cold water test), and an evaporative stimulus (air blast test) using a visual analogue scale. The teeth were evaluated immediately after treatment, and at 4 and 12 weeks after application of the chlorhexidine-containing varnish Cervitec and the glutaraldehyde-containing varnish, Gluma Desensitizer. Statistical analysis indicated that both the desensitising varnishes were effective in alleviating dentine hypersensitivity at all time intervals compared to baseline. There was a highly statistically significantly greater reduction in dentine hypersensitivity to evaporative stimulus, cold stimulus, and tactile stimulus after application of Cervitec than after Gluma Desensitizer (P < 0.001). Both the varnishes have a therapeutic potential to alleviate dentine hypersensitivity at all time intervals compared to baseline. However, Cervitec varnish is more efficacious in reducing dentine hypersensitivity than Gluma varnish at both 4 weeks and 12 weeks post-treatment.

A multiple hold-out framework for Sparse Partial Least Squares.

PubMed

Monteiro, João M; Rao, Anil; Shawe-Taylor, John; Mourão-Miranda, Janaina

2016-09-15

Supervised classification machine learning algorithms may have limitations when studying brain diseases with heterogeneous populations, as the labels might be unreliable. More exploratory approaches, such as Sparse Partial Least Squares (SPLS), may provide insights into the brain's mechanisms by finding relationships between neuroimaging and clinical/demographic data. The identification of these relationships has the potential to improve the current understanding of disease mechanisms, refine clinical assessment tools, and stratify patients. SPLS finds multivariate associative effects in the data by computing pairs of sparse weight vectors, where each pair is used to remove its corresponding associative effect from the data by matrix deflation, before computing additional pairs. We propose a novel SPLS framework which selects the adequate number of voxels and clinical variables to describe each associative effect, and tests their reliability by fitting the model to different splits of the data. As a proof of concept, the approach was applied to find associations between grey matter probability maps and individual items of the Mini-Mental State Examination (MMSE) in a clinical sample with various degrees of dementia. The framework found two statistically significant associative effects between subsets of brain voxels and subsets of the questions/tasks. SPLS was compared with its non-sparse version (PLS). The use of projection deflation versus a classical PLS deflation was also tested in both PLS and SPLS. SPLS outperformed PLS, finding statistically significant effects and providing higher correlation values in hold-out data. Moreover, projection deflation provided better results. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

Trends in total column ozone measurements

NASA Technical Reports Server (NTRS)

Rowland, F. S.; Angell, J.; Attmannspacher, W.; Bloomfield, P.; Bojkov, R. D.; Harris, N.; Komhyr, W.; Mcfarland, M.; Mcpeters, R.; Stolarski, R. S.

1989-01-01

It is important to ensure the best available data are used in any determination of possible trends in total ozone in order to have the most accurate estimates of any trends and the associated uncertainties. Accordingly, the existing total ozone records were examined in considerable detail. Once the best data set has been produced, the statistical analysis must examine the data for any effects that might indicate changes in the behavior of global total ozone. The changes at any individual measuring station could be local in nature, and herein, particular attention was paid to the seasonal and latitudinal variations of total ozone, because two dimensional photochemical models indicate that any changes in total ozone would be most pronounced at high latitudes during the winter months. The conclusions derived from this detailed examination of available total ozone can be split into two categories, one concerning the quality and the other the statistical analysis of the total ozone record.

Statistical gamma-ray decay studies at iThemba LABS

NASA Astrophysics Data System (ADS)

Wiedeking, M.; Bernstein, L. A.; Bleuel, D. L.; Brits, C. P.; Sowazi, K.; Görgen, A.; Goldblum, B. L.; Guttormsen, M.; Kheswa, B. V.; Larsen, A. C.; Majola, S. N. T.; Malatji, K. L.; Negi, D.; Nogwanya, T.; Siem, S.; Zikhali, B. R.

2017-09-01

A program to study the γ-ray decay from the region of high-level density has been established at iThemba LABS, where a high-resolution gamma-ray detector array is used in conjunction with silicon particle-telescopes. Results from two recent projects are presented: 1) The 74Ge(α,α'γ) reaction was used to investigate the Pygmy Dipole Resonance. The results were compared to (γ,γ') data and indicate that the dipole states split into mixed isospin and relatively pure isovector excitations. 2) Data from the 95Mo(d,p) reaction were used to develop a novel method for the determination of spins for low-lying discrete levels utilizing statistical γ-ray decay in the vicinity of the neutron separation energy. These results provide insight into the competition of (γ,n) and (γ,γ') reactions and highlights the need to correct for angular momentum barrier effects.

Statistical Study of the Properties of Magnetosheath Lion Roars using MMS observations

NASA Astrophysics Data System (ADS)

Giagkiozis, S.; Wilson, L. B., III

2017-12-01

Intense whistler-mode waves of very short duration are frequently encountered in the magnetosheath. These emissions have been linked to mirror mode waves and the Earth's bow shock. They can efficiently transfer energy between different plasma populations. These electromagnetic waves are commonly referred to as Lion roars (LR), due to the sound generated when the signals are sonified. They are generally observed during dips of the magnetic field that are anti-correlated with increases of density. Using MMS data, we have identified more than 1750 individual LR burst intervals. Each emission was band-pass filtered and further split into >35,000 subintervals, for which the direction of propagation and the polarization were calculated. The analysis of subinterval properties provides a more accurate representation of their true nature than the more commonly used time- and frequency-averaged dynamic spectra analysis. The results of the statistical analysis of the wave properties will be presented.

Analysis of Convair 990 rejected-takeoff accident with emphasis on decision making, training and procedures

NASA Technical Reports Server (NTRS)

Batthauer, Byron E.

1987-01-01

This paper analyzes a NASA Convair 990 (CV-990) accident with emphasis on rejected-takeoff (RTO) decision making, training, procedures, and accident statistics. The NASA Aircraft Accident Investigation Board was somewhat perplexed that an aircraft could be destroyed as a result of blown tires during the takeoff roll. To provide a better understanding of tire failure RTO's, The Board obtained accident reports, Federal Aviation Administration (FAA) studies, and other pertinent information related to the elements of this accident. This material enhanced the analysis process and convinced the Accident Board that high-speed RTO's in transport aircraft should be given more emphasis during pilot training. Pilots should be made aware of various RTO situations and statistics with emphasis on failed-tire RTO's. This background information could enhance the split-second decision-making process that is required prior to initiating an RTO.

Kinetic isotope effects and how to describe them

PubMed Central

Karandashev, Konstantin; Xu, Zhen-Hao; Meuwly, Markus; Vaníček, Jiří; Richardson, Jeremy O.

2017-01-01

We review several methods for computing kinetic isotope effects in chemical reactions including semiclassical and quantum instanton theory. These methods describe both the quantization of vibrational modes as well as tunneling and are applied to the ⋅H + H2 and ⋅H + CH4 reactions. The absolute rate constants computed with the semiclassical instanton method both using on-the-fly electronic structure calculations and fitted potential-energy surfaces are also compared directly with exact quantum dynamics results. The error inherent in the instanton approximation is found to be relatively small and similar in magnitude to that introduced by using fitted surfaces. The kinetic isotope effect computed by the quantum instanton is even more accurate, and although it is computationally more expensive, the efficiency can be improved by path-integral acceleration techniques. We also test a simple approach for designing potential-energy surfaces for the example of proton transfer in malonaldehyde. The tunneling splittings are computed, and although they are found to deviate from experimental results, the ratio of the splitting to that of an isotopically substituted form is in much better agreement. We discuss the strengths and limitations of the potential-energy surface and based on our findings suggest ways in which it can be improved. PMID:29282447

Supplementation of H1N1pdm09 split vaccine with heterologous tandem repeat M2e5x virus-like particles confers improved cross-protection in ferrets.

PubMed

Music, Nedzad; Reber, Adrian J; Kim, Min-Chul; York, Ian A; Kang, Sang-Moo

2016-01-20

Current influenza vaccines induce strain-specific immunity to the highly variable hemagglutinin (HA) protein. It is therefore a high priority to develop vaccines that induce broadly cross-protective immunity to different strains of influenza. Since influenza A M2 proteins are highly conserved among different strains, five tandem repeats of the extracellular peptide of M2 in a membrane-anchored form on virus-like particles (VLPs) have been suggested to be a promising candidate for universal influenza vaccine. In this study, ferrets were intramuscularly immunized with 2009 H1N1 split HA vaccine ("Split") alone, influenza split vaccine supplemented with M2e5x VLP ("Split+M2e5x"), M2e5x VLP alone ("M2e5x"), or mock immunized. Vaccine efficacy was measured serologically and by protection against a serologically distinct viral challenge. Ferrets immunized with Split+M2e5x induced HA strain specific and conserved M2e immunity. Supplementation of M2e5x VLP to split vaccination significantly increased the immunogenicity of split vaccine compared to split alone. The Split+M2e5x ferret group showed evidence of cross-reactive protection, including faster recovery from weight loss, and reduced inflammation, as inferred from changes in peripheral leukocyte subsets, compared to mock-immunized animals. In addition, ferrets immunized with Split+M2e5x shed lower viral nasal-wash titers than the other groups. Ferrets immunized with M2e5x alone also show some protective effects, while those immunized with split vaccine alone induced no protective effects compared to mock-immunized ferrets. These studies suggest that supplementation of split vaccine with M2e5x-VLP may provide broader and improved cross-protection than split vaccine alone. Published by Elsevier Ltd.

To compare the gingival melanin repigmentation after diode laser application and surgical removal.

PubMed

Mahajan, Gaurav; Kaur, Harjit; Jain, Sanjeev; Kaur, Navnit; Sehgal, Navneet Kaur; Gautam, Aditi

2017-01-01

The aim of the present study is to compare the gingival melanin repigmentation after diode laser application and surgical removal done by scraping with Kirkland knife. This study was a randomized split-mouth study where 10 patients presenting with unattractive, diffuse, dark brown to black gingival discoloration on the facial aspect of the maxillary gingiva were treated by diode laser application and surgical removal and followed up for 3-, 6-, and 9-month intervals. The results showed a statistically significant difference in repigmentation between the groups at the interval of 3 months ( P = 0.040), but the difference was statistically not significant at 6 months ( P = 0.118) and 9 months ( P = 0.146). On surgically treated sites, all cases showed repigmentation of the gingiva, but in laser treated, there were two individuals which did not show repigmentation of the gingiva even at the end of 9-month observation time. The incidence of repigmentation was slightly less in laser-treated sites as compared to surgical depigmentation although the difference was statistically significant only up to 3 months.

Signals of dynamical and statistical process from IMF-IMF correlation function

NASA Astrophysics Data System (ADS)

Pagano, E. V.; Acosta, L.; Auditore, L.; Baran, V.; Cap, T.; Cardella, G.; Colonna, M.; De Luca, S.; De Filippo, E.; Dell'Aquila, D.; Francalanza, L.; Gnoffo, B.; Lanzalone, G.; Lombardo, I.; Maiolino, C.; Martorana, N. S.; Norella, S.; Pagano, A.; Papa, M.; Piasecki, E.; Pirrone, S.; Politi, G.; Porto, F.; Quattrocchi, L.; Rizzo, F.; Rosato, E.; Russotto, P.; Siwek-Wilczyńska, K.; Trifiro, A.; Trimarchi, M.; Verde, G.; Vigilante, M.; Wilczyńsky, J.

2017-11-01

In this paper we briefly discuss about a novel application of the IMF-IMF correlation function to the physical case of binary massive projectile-like (PLF) splitting for dynamical and statistical breakup/fission in heavy ion collisions at Fermi energy. Theoretical simulations are also shown for comparisons with the data. These preliminary results have been obtained for the reverse kinematics reaction 124Sn + 64Ni at 35 AMeV that was studied using the forward part of CHIMERA detector. In that reaction a strong competition between a dynamical and a statistical components and its evolution with the charge asymmetry of the binary break up was already shown. In this work we show that the IMF-IMF correlation function can be used to pin down the timescale of the fragments production in binary fission-like phenomena. We also made simulations with the CoMDII model in order to compare to the experimental IMF-IMF correlation function. In future we plan to extend these studies to different reaction mechanisms and nuclear systems and to compare with different theoretical transport simulations.

Statistical analysis on experimental calibration data for flowmeters in pressure pipes

NASA Astrophysics Data System (ADS)

Lazzarin, Alessandro; Orsi, Enrico; Sanfilippo, Umberto

2017-08-01

This paper shows a statistical analysis on experimental calibration data for flowmeters (i.e.: electromagnetic, ultrasonic, turbine flowmeters) in pressure pipes. The experimental calibration data set consists of the whole archive of the calibration tests carried out on 246 flowmeters from January 2001 to October 2015 at Settore Portate of Laboratorio di Idraulica “G. Fantoli” of Politecnico di Milano, that is accredited as LAT 104 for a flow range between 3 l/s and 80 l/s, with a certified Calibration and Measurement Capability (CMC) - formerly known as Best Measurement Capability (BMC) - equal to 0.2%. The data set is split into three subsets, respectively consisting in: 94 electromagnetic, 83 ultrasonic and 69 turbine flowmeters; each subset is analysed separately from the others, but then a final comparison is carried out. In particular, the main focus of the statistical analysis is the correction C, that is the difference between the flow rate Q measured by the calibration facility (through the accredited procedures and the certified reference specimen) minus the flow rate QM contemporarily recorded by the flowmeter under calibration, expressed as a percentage of the same QM .

Artificial magnetic-field quenches in synthetic dimensions

NASA Astrophysics Data System (ADS)

Yılmaz, F.; Oktel, M. Ö.

2018-02-01

Recent cold atom experiments have realized models where each hyperfine state at an optical lattice site can be regarded as a separate site in a synthetic dimension. In such synthetic ribbon configurations, manipulation of the transitions between the hyperfine levels provide direct control of the hopping in the synthetic dimension. This effect was used to simulate a magnetic field through the ribbon. Precise control over the hopping matrix elements in the synthetic dimension makes it possible to change this artificial magnetic field much faster than the time scales associated with atomic motion in the lattice. In this paper, we consider such a magnetic-flux quench scenario in synthetic dimensions. Sudden changes have not been considered for real magnetic fields as such changes in a conducting system would result in large induced currents. Hence we first study the difference between a time varying real magnetic field and an artificial magnetic field using a minimal six-site model. This minimal model clearly shows the connection between gauge dependence and the lack of on-site induced scalar potential terms. We then investigate the dynamics of a wave packet in an infinite two- or three-leg ladder following a flux quench and find that the gauge choice has a dramatic effect on the packet dynamics. Specifically, a wave packet splits into a number of smaller packets moving with different velocities. Both the weights and the number of packets depend on the implemented gauge. If an initial packet, prepared under zero flux in an n -leg ladder, is quenched to Hamiltonian with a vector potential parallel to the ladder, it splits into at most n smaller wave packets. The same initial wave packet splits into up to n2 packets if the vector potential is implemented to be along the rungs. Even a trivial difference in the gauge choice such as the addition of a constant to the vector potential produces observable effects. We also calculate the packet weights for arbitrary initial and final fluxes. Finally, we show that edge states in a thick ribbon are robust under the quench only when the same gap supports an edge state for the final Hamiltonian.

GEM: a dynamic tracking model for mesoscale eddies in the ocean

NASA Astrophysics Data System (ADS)

Li, Qiu-Yang; Sun, Liang; Lin, Sheng-Fu

2016-12-01

The Genealogical Evolution Model (GEM) presented here is an efficient logical model used to track dynamic evolution of mesoscale eddies in the ocean. It can distinguish between different dynamic processes (e.g., merging and splitting) within a dynamic evolution pattern, which is difficult to accomplish using other tracking methods. To this end, the GEM first uses a two-dimensional (2-D) similarity vector (i.e., a pair of ratios of overlap area between two eddies to the area of each eddy) rather than a scalar to measure the similarity between eddies, which effectively solves the "missing eddy" problem (temporarily lost eddy in tracking). Second, for tracking when an eddy splits, the GEM uses both "parent" (the original eddy) and "child" (eddy split from parent) and the dynamic processes are described as the birth and death of different generations. Additionally, a new look-ahead approach with selection rules effectively simplifies computation and recording. All of the computational steps are linear and do not include iteration. Given the pixel number of the target region L, the maximum number of eddies M, the number N of look-ahead time steps, and the total number of time steps T, the total computer time is O(LM(N + 1)T). The tracking of each eddy is very smooth because we require that the snapshots of each eddy on adjacent days overlap one another. Although eddy splitting or merging is ubiquitous in the ocean, they have different geographic distributions in the North Pacific Ocean. Both the merging and splitting rates of the eddies are high, especially at the western boundary, in currents and in "eddy deserts". The GEM is useful not only for satellite-based observational data, but also for numerical simulation outputs. It is potentially useful for studying dynamic processes in other related fields, e.g., the dynamics of cyclones in meteorology.

Comparative studies on different nanofiber photocatalysts for water splitting

NASA Astrophysics Data System (ADS)

Alharbi, Abdulaziz; Alarifi, Ibrahim M.; Khan, Waseem S.; Asmatulu, Ramazan

2016-04-01

Water splitting using photocatalyst has become a topic of recent investigation since it has the potential of producing hydrogen for clean energy from sunlight. An extensive number of solid photocatalysts have been studied for overall water splitting in recent years. In this study, two methods were employed to synthesize two different photocatalysts for water splitting. The first method describes the synthesis of nickel oxide-loaded strontium titanate (NiO-SrTiO3) particles on electrospun polyacrylonitrile (PAN) nanofibers incorporated with graphene nanoplatelets for water splitting. The electrospun PAN fibers were first oxidized at 270°C for two hours and subsequently immersed in a solution containing ethanol, titanium (IV)-isopropoxide [C12H28O4Ti] and strontium nitrate [Sr(NO3)2]. This solution was then treated with NiO nanoparticles dispersed in toluene. The surface treated PAN fibers were annealed at 600°C in air for 1 hour to transform fibers into a crystalline form for improved photocatalyst performance. In the second method, coaxial electrospinning process was used to produce core/shell strontium titanate/nickel oxide (SrTiO3-NiO) nanofibers. In coaxial method, poly (vinyl pyrrolidone) (PVP) was dissolved in deionized (DI) water, and then titanium (IV) isopropoxide [C12H28O4Ti] and strontium nitrate [Sr(NO3)2] were added into the solution to form the inner (core) layer. For outer (shell) solution, polyacrylonitrile (PAN) polymer was dissolved in dimethylformamide (DMF) at a weight ratio of 10:90 and then nickel oxide was mixed with the solution. Ultraviolet (UV) spectrophotometry and static contact angle measurement techniques were employed to characterize the structural properties of photocatalysts produced by both methods and a comparison was made between the two photocatalysts. The morphology and diameter of the nanofibers were observed by scanning electron microscopy (SEM). The structure and crystallinity of the calcined nanofibers were also observed by means of X-ray diffraction (XRD).

Numerical simulation and experiment on split tungsten carbide cylinder of high pressure apparatus

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

Yang, Yunfei; Li, Mingzhe, E-mail: limz@jlu.edu.cn; Wang, Bolong

2015-12-15

A new high pressure device with a split cylinder was investigated on the basis of the belt-type apparatus. The belt-type die is subjected to excessive tangential tensile stress and the tungsten carbide cylinder is easily damaged in the running process. Taking into account the operating conditions and material properties of the tungsten carbide cylinder, it is divided into 6 blocks to eliminate the tangential tensile stress. We studied two forms of the split type: radial split and tangential split. Simulation results indicate that the split cylinder has more uniform stress distribution and smaller equivalent stress compared with the belt-type cylinder.more » The inner wall of the tangential split cylinder is in the situation that compressive stress is distributed in the axial, radial, and tangential directions. It is similar to the condition of hydrostatic pressure, and it is the best condition for tungsten carbide materials. The experimental results also verify that the tangential split die can bear the highest chamber pressure. Therefore, the tangential split structure can increase the pressure bearing capacity significantly.« less

Bad splits in bilateral sagittal split osteotomy: systematic review of fracture patterns.

PubMed

Steenen, S A; Becking, A G

2016-07-01

An unfavourable and unanticipated pattern of the mandibular sagittal split osteotomy is generally referred to as a 'bad split'. Few restorative techniques to manage the situation have been described. In this article, a classification of reported bad split pattern types is proposed and appropriate salvage procedures to manage the different types of undesired fracture are presented. A systematic review was undertaken, yielding a total of 33 studies published between 1971 and 2015. These reported a total of 458 cases of bad splits among 19,527 sagittal ramus osteotomies in 10,271 patients. The total reported incidence of bad split was 2.3% of sagittal splits. The most frequently encountered were buccal plate fractures of the proximal segment (types 1A-F) and lingual fractures of the distal segment (types 2A and 2B). Coronoid fractures (type 3) and condylar neck fractures (type 4) have seldom been reported. The various types of bad split may require different salvage approaches. Copyright © 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

SU-G-TeP2-11: Initial Evaluation of a Novel Split-Filter Dual-Energy CT for Use in Radiation Oncology

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

Miller, J; Huang, J; Szczykutowicz, T

2016-06-15

Purpose: To perform an initial evaluation of a novel split-filter dual-energy CT (DECT) system with the goal of understanding the clinical utility and limitations of the system for radiation therapy. Methods: Several phantoms were imaged using the split-filter DECT technique on the Siemens Edge CT scanner using a range of clinically-relevant doses. The optimum-contrast reconstruction, the mixed reconstruction, and the monoenergetic reconstructions (ranging from 40 keV to 190 keV) were evaluated. Each image was analyzed for CT number accuracy, uniformity, noise, low-contrast visibility (LCV), spatial resolution and geometric distortion. For comparison purposes, all parameters were evaluated on 120 kVp single-energymore » CT (SECT) scans used for treatment planning, as well as, a sequential-scan DECT technique for corresponding doses. Results: For all DECT reconstructions no observable geometric distortion was found. Both the optimal-contrast and mixed images demonstrated slight improvements in LCV and noise when compared to the SECT, and slight reductions in CT number accuracy and spatial resolution. The CT numbers trended as expected for the monoenergetic reconstructions, with CT number accuracy within 50 HU for materials of density <2 g/cm3. Spatial resolution increased with energy, and for monoenergetic reconstructions >70 keV the spatial resolution exceeded that of the SECT. The noise in the monoenergetic reconstructions increased with decreasing energy. Thus, the image uniformity, signal-to-noise ratio and LCV were diminished at lower energies (70 keV). Applying iterative reconstruction techniques to the low-energy images reduced noise and improved LCV. The signal-to-noise ratio was stable for energies >100 keV. Conclusion: The initial commissioning of the novel split-filter DECT technology demonstrated favorable results for clinical implementation. The mixed reconstruction showed potential as a replacement for the treatment planning SECT. The image parameters for the monoenergetic reconstructions varied appropriately with energy. This work provides an initial understanding of the limitations and potential applications for monoenergetic imaging.« less

Controllable Synthesis of Ni xSe (0.5 ≤ x ≤ 1) Nanocrystals for Efficient Rechargeable Zinc-Air Batteries and Water Splitting.

PubMed

Zheng, Xuerong; Han, Xiaopeng; Liu, Hui; Chen, Jianjun; Fu, Dongju; Wang, Jihui; Zhong, Cheng; Deng, Yida; Hu, Wenbin

2018-04-25

The development of earth-abundant, highly active, and corrosion-resistant electrocatalysts to promote the oxygen reduction reaction (ORR) and oxygen and hydrogen evolution reactions (OER/HER) for rechargeable metal-air batteries and water-splitting devices is urgently needed. In this work, Ni x Se (0.5 ≤ x ≤ 1) nanocrystals with different crystal structures and compositions have been controllably synthesized and investigated as potential electrocatalysts for multifunctional ORR, OER, and HER in alkaline conditions. A novel hot-injection process at ambient pressure was developed to control the phase and composition of a series of Ni x Se by simply adjusting the added molar ratio of the nickel resource to triethylenetetramine. Electrochemical analysis reveals that Ni 0.5 Se nanocrystalline exhibits superior OER activity compared to its counterparts and is comparable to RuO 2 in terms of the low overpotential required to reach a current density of 10 mA cm -2 (330 mV), which may benefit from the pyrite-type crystal structure and Se enrichment in Ni 0.5 Se. For the ORR and HER, Ni 0.75 Se nanoparticles achieve the best performance including lower overpotentials and larger apparent current densities. Further investigations demonstrate that Ni 0.75 Se could not only provide an enhanced electrochemical active area but also facilitate electron transfer during the electrocatalytic process, thus contributing to the remarkable catalytic activity. As a practical application, the Ni 0.75 Se electrode enables rechargeable Zn-air battery with a considerable performance including a long cycling lifetime (200 cycles), high specific capacity (609 mA h g -1 based on the consumed Zn), and low overpotential (0.75 V) at 10 mA cm -2 . Meanwhile, the water-splitting cell setup with an anode of Ni 0.5 Se for the HER and a cathode of Ni 0.75 Se for the OER exhibits a considerable performance with low decay in activity of 12.9% under continuous polarization for 10 h. These results suggest the promising potential of nickel selenide nanocrystals as earth-abundant and high-performance electrocatalysts for metal-air batteries and alkaline water splitting.

GY SAMPLING THEORY IN ENVIRONMENTAL STUDIES 1: ASSESSING SOIL SPLITTING PROTOCOLS

EPA Science Inventory

Five soil sample splitting methods (riffle splitting, paper cone riffle splitting, fractional shoveling, coning and quartering, and grab sampling) were evaluated with synthetic samples to verify Pierre Gy sampling theory expectations. Individually prepared samples consisting of l...

Modeling habitat split: landscape and life history traits determine amphibian extinction thresholds.

PubMed

Fonseca, Carlos Roberto; Coutinho, Renato M; Azevedo, Franciane; Berbert, Juliana M; Corso, Gilberto; Kraenkel, Roberto A

2013-01-01

Habitat split is a major force behind the worldwide decline of amphibian populations, causing community change in richness and species composition. In fragmented landscapes, natural remnants, the terrestrial habitat of the adults, are frequently separated from streams, the aquatic habitat of the larvae. An important question is how this landscape configuration affects population levels and if it can drive species to extinction locally. Here, we put forward the first theoretical model on habitat split which is particularly concerned on how split distance - the distance between the two required habitats - affects population size and persistence in isolated fragments. Our diffusive model shows that habitat split alone is able to generate extinction thresholds. Fragments occurring between the aquatic habitat and a given critical split distance are expected to hold viable populations, while fragments located farther away are expected to be unoccupied. Species with higher reproductive success and higher diffusion rate of post-metamorphic youngs are expected to have farther critical split distances. Furthermore, the model indicates that negative effects of habitat split are poorly compensated by positive effects of fragment size. The habitat split model improves our understanding about spatially structured populations and has relevant implications for landscape design for conservation. It puts on a firm theoretical basis the relation between habitat split and the decline of amphibian populations.

Outcome following right-extended split liver transplantation in the recent transplant era: Single-centre analysis of a German transplant centre.

PubMed

Herden, Uta; Fischer, Lutz; Koch, Martina; Li, Jun; Achilles, Eike-Gert; Nashan, Björn

2018-05-20

When a sufficiently high-quality liver is available, classic liver graft splitting is performed. In such cases, a small child receives the left-lateral split graft, with subsequent transplantation of the right-extended graft in an adult. We analysed 64 patients who received right-extended liver grafts from 2007-2015, and compared outcomes between cases of external versus in-house graft splitting. We found excellent donor data and comparable recipient characteristics. Cold ischemic time was significantly longer for external (14±2 h; n=38) versus internal (12±2 h; n=26) liver graft splitting. Compared to the internal splitting group, the external liver graft splitting group showed significantly reduced 1- and 5-year patient survival (100% versus 84%; P=.035) and higher rates of biliary (24% versus 12%) and vascular (8% versus 0%) complications. The outcomes following right-extended split LTX are disappointing given the excellent organ quality. External liver graft splitting was associated with worse outcome and surgical complication rates. This may be related to the prolonged cold ischemic time due to two-fold transportation, as well as the ignorance of the splitting procedure details and related pitfalls. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Fully coupled six-dimensional calculations of the water dimer vibration-rotation-tunneling states with split Wigner pseudospectral approach. II. Improvements and tests of additional potentials

NASA Astrophysics Data System (ADS)

Fellers, R. S.; Braly, L. B.; Saykally, R. J.; Leforestier, C.

1999-04-01

The SWPS method is improved by the addition of H.E.G. contractions for generating a more compact basis. An error in the definition of the internal fragment axis system used in our previous calculation is described and corrected. Fully coupled 6D (rigid monomers) VRT states are computed for several new water dimer potential surfaces and compared with experiment and our earlier SWPS results. This work sets the stage for refinement of such potential surfaces via regression analysis of VRT spectroscopic data.