WorldWideScience

Sample records for longitudinal two-stage study

  1. Composite likelihood and two-stage estimation in family studies

    DEFF Research Database (Denmark)

    Andersen, Elisabeth Anne Wreford

    2004-01-01

    In this paper register based family studies provide the motivation for linking a two-stage estimation procedure in copula models for multivariate failure time data with a composite likelihood approach. The asymptotic properties of the estimators in both parametric and semi-parametric models are d...

  2. Experimental studies of two-stage centrifugal dust concentrator

    Science.gov (United States)

    Vechkanova, M. V.; Fadin, Yu M.; Ovsyannikov, Yu G.

    2018-03-01

    The article presents data of experimental results of two-stage centrifugal dust concentrator, describes its design, and shows the development of a method of engineering calculation and laboratory investigations. For the experiments, the authors used quartz, ceramic dust and slag. Experimental dispersion analysis of dust particles was obtained by sedimentation method. To build a mathematical model of the process, dust collection was built using central composite rotatable design of the four factorial experiment. A sequence of experiments was conducted in accordance with the table of random numbers. Conclusion were made.

  3. Bias due to two-stage residual-outcome regression analysis in genetic association studies.

    Science.gov (United States)

    Demissie, Serkalem; Cupples, L Adrienne

    2011-11-01

    Association studies of risk factors and complex diseases require careful assessment of potential confounding factors. Two-stage regression analysis, sometimes referred to as residual- or adjusted-outcome analysis, has been increasingly used in association studies of single nucleotide polymorphisms (SNPs) and quantitative traits. In this analysis, first, a residual-outcome is calculated from a regression of the outcome variable on covariates and then the relationship between the adjusted-outcome and the SNP is evaluated by a simple linear regression of the adjusted-outcome on the SNP. In this article, we examine the performance of this two-stage analysis as compared with multiple linear regression (MLR) analysis. Our findings show that when a SNP and a covariate are correlated, the two-stage approach results in biased genotypic effect and loss of power. Bias is always toward the null and increases with the squared-correlation between the SNP and the covariate (). For example, for , 0.1, and 0.5, two-stage analysis results in, respectively, 0, 10, and 50% attenuation in the SNP effect. As expected, MLR was always unbiased. Since individual SNPs often show little or no correlation with covariates, a two-stage analysis is expected to perform as well as MLR in many genetic studies; however, it produces considerably different results from MLR and may lead to incorrect conclusions when independent variables are highly correlated. While a useful alternative to MLR under , the two -stage approach has serious limitations. Its use as a simple substitute for MLR should be avoided. © 2011 Wiley Periodicals, Inc.

  4. A Two-Stage Estimation Method for Random Coefficient Differential Equation Models with Application to Longitudinal HIV Dynamic Data.

    Science.gov (United States)

    Fang, Yun; Wu, Hulin; Zhu, Li-Xing

    2011-07-01

    We propose a two-stage estimation method for random coefficient ordinary differential equation (ODE) models. A maximum pseudo-likelihood estimator (MPLE) is derived based on a mixed-effects modeling approach and its asymptotic properties for population parameters are established. The proposed method does not require repeatedly solving ODEs, and is computationally efficient although it does pay a price with the loss of some estimation efficiency. However, the method does offer an alternative approach when the exact likelihood approach fails due to model complexity and high-dimensional parameter space, and it can also serve as a method to obtain the starting estimates for more accurate estimation methods. In addition, the proposed method does not need to specify the initial values of state variables and preserves all the advantages of the mixed-effects modeling approach. The finite sample properties of the proposed estimator are studied via Monte Carlo simulations and the methodology is also illustrated with application to an AIDS clinical data set.

  5. Empirical study of classification process for two-stage turbo air classifier in series

    Science.gov (United States)

    Yu, Yuan; Liu, Jiaxiang; Li, Gang

    2013-05-01

    The suitable process parameters for a two-stage turbo air classifier are important for obtaining the ultrafine powder that has a narrow particle-size distribution, however little has been published internationally on the classification process for the two-stage turbo air classifier in series. The influence of the process parameters of a two-stage turbo air classifier in series on classification performance is empirically studied by using aluminum oxide powders as the experimental material. The experimental results show the following: 1) When the rotor cage rotary speed of the first-stage classifier is increased from 2 300 r/min to 2 500 r/min with a constant rotor cage rotary speed of the second-stage classifier, classification precision is increased from 0.64 to 0.67. However, in this case, the final ultrafine powder yield is decreased from 79% to 74%, which means the classification precision and the final ultrafine powder yield can be regulated through adjusting the rotor cage rotary speed of the first-stage classifier. 2) When the rotor cage rotary speed of the second-stage classifier is increased from 2 500 r/min to 3 100 r/min with a constant rotor cage rotary speed of the first-stage classifier, the cut size is decreased from 13.16 μm to 8.76 μm, which means the cut size of the ultrafine powder can be regulated through adjusting the rotor cage rotary speed of the second-stage classifier. 3) When the feeding speed is increased from 35 kg/h to 50 kg/h, the "fish-hook" effect is strengthened, which makes the ultrafine powder yield decrease. 4) To weaken the "fish-hook" effect, the equalization of the two-stage wind speeds or the combination of a high first-stage wind speed with a low second-stage wind speed should be selected. This empirical study provides a criterion of process parameter configurations for a two-stage or multi-stage classifier in series, which offers a theoretical basis for practical production.

  6. Statistical inference for extended or shortened phase II studies based on Simon's two-stage designs.

    Science.gov (United States)

    Zhao, Junjun; Yu, Menggang; Feng, Xi-Ping

    2015-06-07

    Simon's two-stage designs are popular choices for conducting phase II clinical trials, especially in the oncology trials to reduce the number of patients placed on ineffective experimental therapies. Recently Koyama and Chen (2008) discussed how to conduct proper inference for such studies because they found that inference procedures used with Simon's designs almost always ignore the actual sampling plan used. In particular, they proposed an inference method for studies when the actual second stage sample sizes differ from planned ones. We consider an alternative inference method based on likelihood ratio. In particular, we order permissible sample paths under Simon's two-stage designs using their corresponding conditional likelihood. In this way, we can calculate p-values using the common definition: the probability of obtaining a test statistic value at least as extreme as that observed under the null hypothesis. In addition to providing inference for a couple of scenarios where Koyama and Chen's method can be difficult to apply, the resulting estimate based on our method appears to have certain advantage in terms of inference properties in many numerical simulations. It generally led to smaller biases and narrower confidence intervals while maintaining similar coverages. We also illustrated the two methods in a real data setting. Inference procedures used with Simon's designs almost always ignore the actual sampling plan. Reported P-values, point estimates and confidence intervals for the response rate are not usually adjusted for the design's adaptiveness. Proper statistical inference procedures should be used.

  7. On bi-criteria two-stage transportation problem: a case study

    Directory of Open Access Journals (Sweden)

    Ahmad MURAD

    2010-01-01

    Full Text Available The study of the optimum distribution of goods between sources and destinations is one of the important topics in projects economics. This importance comes as a result of minimizing the transportation cost, deterioration, time, etc. The classical transportation problem constitutes one of the major areas of application for linear programming. The aim of this problem is to obtain the optimum distribution of goods from different sources to different destinations which minimizes the total transportation cost. From the practical point of view, the transportation problems may differ from the classical form. It may contain one or more objective function, one or more stage to transport, one or more type of commodity with one or more means of transport. The aim of this paper is to construct an optimization model for transportation problem for one of mill-stones companies. The model is formulated as a bi-criteria two-stage transportation problem with a special structure depending on the capacities of suppliers, warehouses and requirements of the destinations. A solution algorithm is introduced to solve this class of bi-criteria two-stage transportation problem to obtain the set of non-dominated extreme points and the efficient solutions accompanied with each one that enables the decision maker to choose the best one. The solution algorithm mainly based on the fruitful application of the methods for treating transportation problems, theory of duality of linear programming and the methods of solving bi-criteria linear programming problems.

  8. Study of two-stage turbine characteristic and its influence on turbo-compound engine performance

    International Nuclear Information System (INIS)

    Zhao, Rongchao; Zhuge, Weilin; Zhang, Yangjun; Yang, Mingyang; Martinez-Botas, Ricardo; Yin, Yong

    2015-01-01

    Highlights: • An analytical model was built to study the interactions between two turbines in series. • The impacts of HP VGT and LP VGT on turbo-compound engine performance were investigated. • The fuel reductions obtained by HP VGT at 1900 rpm and 1000 rpm are 3.08% and 7.83% respectively. • The optimum value of AR ranged from 2.0 to 2.5 as the turbo-compound engine speed decreases. - Abstract: Turbo-compounding is an effective way to recover waste heat from engine exhaust and reduce fuel consumption for internal combustion engine (ICE). The characteristics of two-stage turbine, including turbocharger turbine and power turbine, have significant effects on the overall performance of turbo-compound engine. This paper investigates the interaction between two turbines in a turbo-compound engine and its impact on the engine performance. Firstly an analytical model is built to investigate the effects of turbine equivalent flow area on the two-stage turbine characteristics, including swallowing capacity and load split. Next both simulation and experimental method are carried out to study the effects of high pressure variable geometry turbine (HP VGT), low pressure variable geometry turbine (LP VGT) and combined VGT on the engine overall performance. The results show that the engine performance is more sensitive to HP VGT compared with LP VGT at all the operation conditions, which is caused by the larger influences of HP VGT on the total expansion ratio and engine air–fuel ratio. Using the HP VGT method, the fuel reductions of the turbo-compound engine at 1900 rpm and 1000 rpm are 3.08% and 7.83% respectively, in comparison with the baseline engine. The corresponding optimum values of AR are 2.0 and 2.5

  9. Experimental and numerical studies on two-stage combustion of biomass

    Energy Technology Data Exchange (ETDEWEB)

    Houshfar, Eshan

    2012-07-01

    In this thesis, two-stage combustion of biomass was experimentally/numerically investigated in a multifuel reactor. The following emissions issues have been the main focus of the work: 1- NOx and N2O 2- Unburnt species (CO and CxHy) 3- Corrosion related emissions.The study had a focus on two-stage combustion in order to reduce pollutant emissions (primarily NOx emissions). It is well known that pollutant emissions are very dependent on the process conditions such as temperature, reactant concentrations and residence times. On the other hand, emissions are also dependent on the fuel properties (moisture content, volatiles, alkali content, etc.). A detailed study of the important parameters with suitable biomass fuels in order to optimize the various process conditions was performed. Different experimental studies were carried out on biomass fuels in order to study the effect of fuel properties and combustion parameters on pollutant emissions. Process conditions typical for biomass combustion processes were studied. Advanced experimental equipment was used in these studies. The experiments showed the effects of staged air combustion, compared to non-staged combustion, on the emission levels clearly. A NOx reduction of up to 85% was reached with staged air combustion using demolition wood as fuel. An optimum primary excess air ratio of 0.8-0.95 was found as a minimizing parameter for the NOx emissions for staged air combustion. Air staging had, however, a negative effect on N2O emissions. Even though the trends showed a very small reduction in the NOx level as temperature increased for non-staged combustion, the effect of temperature was not significant for NOx and CxHy, neither in staged air combustion or non-staged combustion, while it had a great influence on the N2O and CO emissions, with decreasing levels with increasing temperature. Furthermore, flue gas recirculation (FGR) was used in combination with staged combustion to obtain an enhanced NOx reduction. The

  10. SUCCESS FACTORS IN GROWING SMBs: A STUDY OF TWO INDUSTRIES AT TWO STAGES OF DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    Tor Jarl Trondsen

    2002-01-01

    Full Text Available The study attempts to identify factors for growing SMBs. An evolutionary phase approach has been used. The study also aims to find out if there are common and different denominators for newer and older firms that can affect their profitability. The study selects a sampling frame that isolates two groups of firms in two industries at two stages of development. A variety of organizational and structural data was collected and analyzed. Amongst the conclusions that may be drawn from the study are that it is not easy to find a common definition of success, it is important to stratify SMBs when studying them, an evolutionary stage approach helps to compare firms with roughly the same external and internal dynamics and each industry has its own set of success variables.The study has identified three success variables for older firms that reflect contemporary strategic thinking such as crafting a good strategy and changing it only incrementally, building core competencies and outsourcing the rest, and keeping up with innovation and honing competitive skills.

  11. Two-stage case-control association study of dopamine-related genes and migraine

    Directory of Open Access Journals (Sweden)

    Pardo Julio

    2009-09-01

    Full Text Available Abstract Background We previously reported risk haplotypes for two genes related with serotonin and dopamine metabolism: MAOA in migraine without aura and DDC in migraine with aura. Herein we investigate the contribution to migraine susceptibility of eight additional genes involved in dopamine neurotransmission. Methods We performed a two-stage case-control association study of 50 tag single nucleotide polymorphisms (SNPs, selected according to genetic coverage parameters. The first analysis consisted of 263 patients and 274 controls and the replication study was composed by 259 cases and 287 controls. All cases were diagnosed according to ICHD-II criteria, were Spanish Caucasian, and were sex-matched with control subjects. Results Single-marker analysis of the first population identified nominal associations of five genes with migraine. After applying a false discovery rate correction of 10%, the differences remained significant only for DRD2 (rs2283265 and TH (rs2070762. Multiple-marker analysis identified a five-marker T-C-G-C-G (rs12363125-rs2283265-rs2242592-rs1554929-rs2234689 risk haplotype in DRD2 and a two-marker A-C (rs6356-rs2070762 risk haplotype in TH that remained significant after correction by permutations. These results, however, were not replicated in the second independent cohort. Conclusion The present study does not support the involvement of the DRD1, DRD2, DRD3, DRD5, DBH, COMT, SLC6A3 and TH genes in the genetic predisposition to migraine in the Spanish population.

  12. Study on the effect of mutated bacillus megaterium in two-stage fermentation of vitamin C

    International Nuclear Information System (INIS)

    Lv Shujuan; Wang Jun; Yao Jianming; Yu Zengliang

    2003-01-01

    Bacillus megaterium as a companion strain in two-stage fermentation of vitamin C could secrete some active substances to spur growth of Gluconobacter oxydans to produce 2-KLG. In the fermenting system where Gluconobacter oxydans was combined with GB82-a mutated strain of B. megaterium by ion implantation, the amount of 2-KLG harvested was larger than that produced by the original B. megaterium BP52 being substituted for GB82. In this paper, authors studied the effect of the active substances secreted by GB82 to enhance the capability of Gluconobacter oxydans to produce 2-KLG. The supernate of GB82 sampled at different cultivation times all had much more activity to spur Gluconobacter oxydans to yield 2-KLG than that of the original B. megaterium, which might be due to the genetic changes in the active components caused by ion implantation. Furthermore, the active substances of GB82's supernate would lose a part of its activity in extreme environments, which is typical of some proteins

  13. A two-stage genome-wide association study of sporadic amyotrophic lateral sclerosis.

    Science.gov (United States)

    Chiò, Adriano; Schymick, Jennifer C; Restagno, Gabriella; Scholz, Sonja W; Lombardo, Federica; Lai, Shiao-Lin; Mora, Gabriele; Fung, Hon-Chung; Britton, Angela; Arepalli, Sampath; Gibbs, J Raphael; Nalls, Michael; Berger, Stephen; Kwee, Lydia Coulter; Oddone, Eugene Z; Ding, Jinhui; Crews, Cynthia; Rafferty, Ian; Washecka, Nicole; Hernandez, Dena; Ferrucci, Luigi; Bandinelli, Stefania; Guralnik, Jack; Macciardi, Fabio; Torri, Federica; Lupoli, Sara; Chanock, Stephen J; Thomas, Gilles; Hunter, David J; Gieger, Christian; Wichmann, H Erich; Calvo, Andrea; Mutani, Roberto; Battistini, Stefania; Giannini, Fabio; Caponnetto, Claudia; Mancardi, Giovanni Luigi; La Bella, Vincenzo; Valentino, Francesca; Monsurrò, Maria Rosaria; Tedeschi, Gioacchino; Marinou, Kalliopi; Sabatelli, Mario; Conte, Amelia; Mandrioli, Jessica; Sola, Patrizia; Salvi, Fabrizio; Bartolomei, Ilaria; Siciliano, Gabriele; Carlesi, Cecilia; Orrell, Richard W; Talbot, Kevin; Simmons, Zachary; Connor, James; Pioro, Erik P; Dunkley, Travis; Stephan, Dietrich A; Kasperaviciute, Dalia; Fisher, Elizabeth M; Jabonka, Sibylle; Sendtner, Michael; Beck, Marcus; Bruijn, Lucie; Rothstein, Jeffrey; Schmidt, Silke; Singleton, Andrew; Hardy, John; Traynor, Bryan J

    2009-04-15

    The cause of sporadic amyotrophic lateral sclerosis (ALS) is largely unknown, but genetic factors are thought to play a significant role in determining susceptibility to motor neuron degeneration. To identify genetic variants altering risk of ALS, we undertook a two-stage genome-wide association study (GWAS): we followed our initial GWAS of 545 066 SNPs in 553 individuals with ALS and 2338 controls by testing the 7600 most associated SNPs from the first stage in three independent cohorts consisting of 2160 cases and 3008 controls. None of the SNPs selected for replication exceeded the Bonferroni threshold for significance. The two most significantly associated SNPs, rs2708909 and rs2708851 [odds ratio (OR) = 1.17 and 1.18, and P-values = 6.98 x 10(-7) and 1.16 x 10(-6)], were located on chromosome 7p13.3 within a 175 kb linkage disequilibrium block containing the SUNC1, HUS1 and C7orf57 genes. These associations did not achieve genome-wide significance in the original cohort and failed to replicate in an additional independent cohort of 989 US cases and 327 controls (OR = 1.18 and 1.19, P-values = 0.08 and 0.06, respectively). Thus, we chose to cautiously interpret our data as hypothesis-generating requiring additional confirmation, especially as all previously reported loci for ALS have failed to replicate successfully. Indeed, the three loci (FGGY, ITPR2 and DPP6) identified in previous GWAS of sporadic ALS were not significantly associated with disease in our study. Our findings suggest that ALS is more genetically and clinically heterogeneous than previously recognized. Genotype data from our study have been made available online to facilitate such future endeavors.

  14. Study on the Control Algorithm of Two-Stage DC-DC Converter for Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Changhao Piao

    2014-01-01

    Full Text Available The fast response, high efficiency, and good reliability are very important characteristics to electric vehicles (EVs dc/dc converters. Two-stage dc-dc converter is a kind of dc-dc topologies that can offer those characteristics to EVs. Presently, nonlinear control is an active area of research in the field of the control algorithm of dc-dc converters. However, very few papers research on two-stage converter for EVs. In this paper, a fixed switching frequency sliding mode (FSFSM controller and double-integral sliding mode (DISM controller for two-stage dc-dc converter are proposed. And a conventional linear control (lag is chosen as the comparison. The performances of the proposed FSFSM controller are compared with those obtained by the lag controller. In consequence, the satisfactory simulation and experiment results show that the FSFSM controller is capable of offering good large-signal operations with fast dynamical responses to the converter. At last, some other simulation results are presented to prove that the DISM controller is a promising method for the converter to eliminate the steady-state error.

  15. The experimental study of a two-stage photovoltaic thermal system based on solar trough concentration

    International Nuclear Information System (INIS)

    Tan, Lijun; Ji, Xu; Li, Ming; Leng, Congbin; Luo, Xi; Li, Haili

    2014-01-01

    Highlights: • A two-stage photovoltaic thermal system based on solar trough concentration. • Maximum cell efficiency of 5.21% with the mirror opening width of 57 cm. • With single cycle, maximum temperatures rise in the heating stage is 12.06 °C. • With 30 min multiple cycles, working medium temperature 62.8 °C, increased 28.7 °C. - Abstract: A two-stage photovoltaic thermal system based on solar trough concentration is proposed, in which the metal cavity heating stage is added on the basis of the PV/T stage, and thermal energy with higher temperature is output while electric energy is output. With the 1.8 m 2 mirror PV/T system, the characteristic parameters of the space solar cell under non-concentrating solar radiation and concentrating solar radiation are respectively tested experimentally, and the solar cell output characteristics at different opening widths of concentrating mirror of the PV/T stage under condensation are also tested experimentally. When the mirror opening width was 57 cm, the solar cell efficiency reached maximum value of 5.21%. The experimental platform of the two-stage photovoltaic thermal system was established, with a 1.8 m 2 mirror PV/T stage and a 15 m 2 mirror heating stage, or a 1.8 m 2 mirror PV/T stage and a 30 m 2 mirror heating stage. The results showed that with single cycle, the long metal cavity heating stage would bring lower thermal efficiency, but temperature rise of the working medium is higher, up to 12.06 °C with only single cycle. With 30 min closed multiple cycles, the temperature of the working medium in the water tank was 62.8 °C, with an increase of 28.7 °C, and thermal energy with higher temperature could be output

  16. Study on a high capacity two-stage free piston Stirling cryocooler working around 30 K

    Science.gov (United States)

    Wang, Xiaotao; Zhu, Jian; Chen, Shuai; Dai, Wei; Li, Ke; Pang, Xiaomin; Yu, Guoyao; Luo, Ercang

    2016-12-01

    This paper presents a two-stage high-capacity free-piston Stirling cryocooler driven by a linear compressor to meet the requirement of the high temperature superconductor (HTS) motor applications. The cryocooler system comprises a single piston linear compressor, a two-stage free piston Stirling cryocooler and a passive oscillator. A single stepped displacer configuration was adopted. A numerical model based on the thermoacoustic theory was used to optimize the system operating and structure parameters. Distributions of pressure wave, phase differences between the pressure wave and the volume flow rate and different energy flows are presented for a better understanding of the system. Some characterizing experimental results are presented. Thus far, the cryocooler has reached a lowest cold-head temperature of 27.6 K and achieved a cooling power of 78 W at 40 K with an input electric power of 3.2 kW, which indicates a relative Carnot efficiency of 14.8%. When the cold-head temperature increased to 77 K, the cooling power reached 284 W with a relative Carnot efficiency of 25.9%. The influences of different parameters such as mean pressure, input electric power and cold-head temperature are also investigated.

  17. Effekt of a two-stage nursing assesment and intervention - a randomized intervention study

    DEFF Research Database (Denmark)

    Rosted, Elizabeth Emilie; Poulsen, Ingrid; Hendriksen, Carsten

    % of geriatric patients have complex and often unresolved caring needs. The objective was to examine the effect of a two-stage nursing assessment and intervention to address the patients uncompensated problems given just after discharge from ED and one and six months after. Method: We conducted a prospective...... nursing assessment comprising a checklist of 10 physical, mental, medical and social items. The focus was on unresolved problems which require medical intervention, new or different home care services, or comprehensive geriatric assessment. Following this the nurses made relevant referrals...... to the geriatric outpatient clinic, community health centre, primary physician or arrangements with next-of-kin. Findings: Primary endpoints will be presented as unplanned readmission to ED; admission to nursing home; and death. Secondary endpoints will be presented as physical function; depressive symptoms...

  18. Two-stage dental implants inserted in a one-stage procedure : a prospective comparative clinical study

    NARCIS (Netherlands)

    Heijdenrijk, Kees

    2002-01-01

    The results of this study indicate that dental implants designed for a submerged implantation procedure can be used in a single-stage procedure and may be as predictable as one-stage implants. Although one-stage implant systems and two-stage.

  19. Studies on quantitative physiology of Trichoderma reesei with two-stage continuous culture for cellulase production

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, D; Andreotti, R; Mandels, M; Gallo, B; Reese, E T

    1979-11-01

    By employing a two-stage continuous-culture system, some of the more important physiological parameters involved in cellulase biosynthesis have been evaluated with an ultimate objective of designing an optimally controlled cellulase process. The two-stage continuous-culture system was run for a period of 1350 hr with Trichoderma reesei strain MCG-77. The temperature and pH were controlled at 32/sup 0/C and pH 4.5 for the first stage (growth) and 28/sup 0/C and pH 3.5 for the second stage (enzyme production). Lactose was the only carbon source for both stages. The ratio of specific uptake rate of carbon to that of nitrogen, Q(C)/Q(N), that supported good cell growth ranged from 11 to 15, and the ratio for maximum specific enzyme productivity ranged from 5 to 13. The maintenance coefficients determined for oxygen, M/sub 0/, and for carbon source, M/sub c/, are 0.85 mmol O/sub 2//g biomass/hr and 0.14 mmol hexose/g biomass/hr, respectively. The yield constants determined are: Y/sub X/O/ = 32.3 g biomass/mol O/sub 2/, Y/sub X/C/ = 1.1 g biomass/g C or Y/sub X/C/ = 0.44 g biomass/g hexose, Y/sub X/N/ = 12.5 g biomass/g nitrogen for the cell growth stage, and Y/sub X/N/ = 16.6 g biomass/g nitrogen for the enzyme production stage. Enzyme was produced only in the second stage. Volumetric and specific enzyme productivities obtained were 90 IU/liter/hrand 8 IU/g biomass/hr, respectively. The maximum specific enzyme productivity observed was 14.8 IU/g biomass/hr. The optimal dilution rate in the second stage that corresponded to the maximum enzyme productivity was 0.026 approx. 0.028 hr/sup -1/, and the specific growth rate in the second stage that supported maximum specific enzyme productivity was equal to or slightly less than zero.

  20. The study on a gas-coupled two-stage stirling-type pulse tube cryocooler

    Science.gov (United States)

    Wu, X. L.; Chen, L. B.; Zhu, X. S.; Pan, C. Z.; Guo, J.; Wang, J. J.; Zhou, Y.

    2017-12-01

    A two-stage gas-coupled Stirling-type pulse tube cryocooler (SPTC) driven by a linear dual-opposed compressor has been designed, manufactured and tested. Both of the stages adopted coaxial structure for compactness. The effect of a cold double-inlet at the second stage on the cooling performance was investigated. The test results show that the cold double-inlet will help to achieve a lower cooling temperature, but it is not conducive to achieving a higher cooling capacity. At present, without the cold double-inlet, the second stage has achieved a no-load temperature of 11.28 K and a cooling capacity of 620 mW/20 K with an input electric power of 450 W. With the cold double-inlet, the no-load temperature is lowered to 9.4 K, but the cooling capacity is reduced to 400 mW/20 K. The structure of the developed cryocooler and the influences of charge pressure, operating frequency and hot end temperature will also be introduced in this paper.

  1. [Study on supply and demand relation based on two stages division of market of Chinese materia medica].

    Science.gov (United States)

    Yang, Guang; Guo, Lan-Ping; Wang, Nuo; Zeng, Yan; Huang, Lu-Qi

    2014-01-01

    The complex production processes and long industrial chain in traditional Chinese medicine (TCM) market result in difficulty in Chinese market microstructure research. Based on the defining the logical relationships among different concepts. This paper divides TCM market into two stages as Chinese materia medica resource market and traditional Chinese Patent Medicines market. Under this foundation, we investigated the supply capacity, approaching rules and motivation system of suppliers in TCM market, analyzed the demand situation in the perspective of demand side, and evaluated the purchasing power in terms of population profile, income, and insurance. Furthermore we also analyzed the price formation mechanism in two stages of TCM market. We hope this study can make a positive and promotion effect on TCM market related research.

  2. Two-stage estimation in copula models used in family studies

    DEFF Research Database (Denmark)

    Andersen, Elisabeth Anne Wreford

    2005-01-01

    by Shih and Louis (Biometrics vol. 51, pp. 1384-1399, 1995b) and Glidden (Lifetime Data Analysis vol. 6, pp. 141-156, 2000). Because register based family studies often involve very large cohorts a method for analysing a sampled cohort is also derived together with the asymptotic properties...... of the estimators. The proposed methods are studied in simulations and the estimators are found to be highly efficient. Finally, the methods are applied to a study of mortality in twins....

  3. Study and development of a two-stage light gas gun

    International Nuclear Information System (INIS)

    Lezaud, Jean-Michel

    1976-01-01

    After recalling the definition of principal dimensional internal characteristics of a light gas gun studied and developed at Commissariat a l'Energie Atomique, we present the interior ballistics calculation systems in fixed working conditions: these conditions permit to accelerate a 400 g projectile to 6500 m/s speed. About these conditions is studied the influence of some operating parameters: weight of piston, initial pressure of hydrogen, breaking pressure of diaphragms. Afterwards is presented a study of dynamic axial stresses. The consequence of these stresses in certain cross sections of gun has led to conceive the original solution of gun called gun sliding launching tube. At last, some special points appropriated to operating or working methods (optimisation of convergent, extrusion of piston, failure of diaphragms, position of target, circuits of fluids) are presented. (author) [fr

  4. Determinants of the incidence of childhood asthma: a two-stage case-control study.

    Science.gov (United States)

    Martel, Marie-Josée; Rey, Evelyne; Malo, Jean-Luc; Perreault, Sylvie; Beauchesne, Marie-France; Forget, Amélie; Blais, Lucie

    2009-01-15

    Extensive literature exists on potential risk factors for childhood asthma. To the authors' knowledge, no investigators have yet attempted to disentangle the effects of those determinants within a single study setting. The authors aimed to evaluate the independent effects of 47 potential determinants (from the prenatal, perinatal, and childhood periods) of asthma development in children within the first 10 years of life. From a Canadian birth cohort of 26,265 children (1990-2002), a 2-stage case-control study was conducted. In the first stage, 20 controls per case were selected from 3 administrative databases. In the second stage, selected mothers were mailed questionnaires for assessment of additional determinants. Increased risks of childhood asthma were found for > or =1 previous diagnosis of bronchopulmonary disease and atopic dermatitis in the child, oxygen administration after birth, prescription of antibiotics within the first 6 months of life, male gender, asthma during pregnancy, use of antibiotics during pregnancy, maternal receipt of social aid, paternal asthma, and asthma in siblings. Protective effects included use of intranasal corticosteroids during pregnancy, having a wood-burning fireplace, having pets in the home prior to the index date, breastfeeding, and day-care attendance. This study allowed the authors to identify, within a single setting, the most influential determinants of childhood asthma among 47 predictors assessed for the prenatal, perinatal, and childhood periods.

  5. Two-stage implant placement technique for the management of irradiated jaws: An animal study.

    Science.gov (United States)

    Aboushelib, Moustafa N; Arnaout, Mohamed A; Elsafi, Mohamed H; Kassem, Youssef M

    2017-10-01

    Radiotherapy results in diminished bone remodeling capacity and an elevated risk of osteoradionecrosis, which can negatively influence the survival rate of dental implants. Patients receiving radiotherapy are advised not to receive dental implants during or soon after completing their radiotherapy. The purpose of this animal study was to investigate a 2-stage implant placement technique designed to diminish applied trauma on irradiated bone. Two groups of white New Zealand rabbits received radiotherapy in ascending doses (2, 4, 8 Gy), while a nonirradiated group served as control. Three weeks after completion of the last radiotherapy session, one of the irradiated groups and the control group received titanium dental implants bilaterally in the femur head. For the second irradiated group, an osteotomy was performed, and the surgical wound was left to heal for 2 weeks before implant placement. All animals were sacrificed 4 weeks after implant placement, and histomorphometric analysis was used to study bone-implant contact (n=14, α=.05). Statistical analysis revealed significantly higher (F=159, P<.001) bone-implant contact in the 2-stage (40.2 ±1.9) implant placement technique than in the immediately placed implants (21.2 ±2.3) in irradiated bone. Both of the groups had a significantly lower bone-to-implant contact ratio than the non-irradiated control (64.2 ±3.8). Within the limitations of this animal study, the 2-stage implant placement technique could be used to reduce trauma in irradiated bone and to improve wound healing around dental implants. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  6. Experimental study on two-stage air supply downdraft gasifier and dual fuel engine system

    Energy Technology Data Exchange (ETDEWEB)

    Nhuchhen, Daya Ram; Salam, P.A. [Asian Institute of Technology, Energy Field of Study, School of Environment Resource and Development, P. O. Box 4, Klong Luang, Pathumthani (Thailand)

    2012-06-15

    Biomass is a widely used renewable energy resource with net balanced carbon dioxide absorptions and emissions. An inefficient use of solid biomass in combustion process emits more gaseous pollutants, increasing the pollution level. Biomass gasification is one of the techniques to support efficient use of biomass. Multistage gasification is a method of gasification to improve quality of the producer gas in which two separate reactors are designed for separating gasification reactions. This study presents experimental results of gasification using Eucalyptus wood in a single long cylindrical reactor with two air supply ports, i.e., primary and secondary. The effect of different air supply rates on the heating values of the producer gas was studied. Optimum primary and secondary air supply rate of 100 and 80 l/min at equivalence ratio of 0.38 was observed with producer gas lower heating value of 4.72 MJ Nm{sup -3}. The performance of a diesel engine in the dual fuel mode was also evaluated. The overall gasifier engine system efficiency was 13.86 % at an electrical load of 10.54 kW{sub e} with specific energy consumption of 16.22 MJ kWh{sup -1}. The heat recovery system was designed and tested to recover heat from producer gas in the form of hot water. (orig.)

  7. Two stage study of wound microorganisms affecting burns and plastic surgery inpatients.

    Science.gov (United States)

    Miranda, Benjamin H; Ali, Syed N; Jeffery, Steven L A; Thomas, Sunil S

    2008-01-01

    This study was designed to identify wound microorganisms and the reasons for differing prevalence between the wards, burns unit and intensive care unit (ICU) in a regional centre for burns and plastic surgery. Antibiotic sensitivities of the 10 most prevalent microorganisms cultured from inpatient wound swabs were also investigated. Inpatient wound swab data were collected retrospectively using notes and departmental database information between January and June 2007. Data were analyzed using chi-squared tests and P-values. Eight hundred five positive wound swabs from 204 swab positive inpatients were analyzed. Stage 1 of this study demonstrated 917 positive swab episodes and 30 varieties of organism. The five most prevalent organisms cultured were Staphylococcus (23.9%), Acinetobacter (21.2%), Methicillin Resistant Staphylococcus aureus (MRSA) (20.8%), Pseudomonas (9.7%) and Enterococcus (5.2%). Stage 2 revealed that Acinetobacter baumanni (ABAU) was significantly more prevalent in military over civilian inpatients (P < .001) and that military inpatients had a significantly greater proportion of ABAU over civilian inpatients within the first 24 hours after admission (P < .001). ABAU episodes were significantly higher on the ICU over the burns unit and on the wards (P < .001). MRSA was significantly more prevalent in military inpatients (P < .001); however, no significant difference was observed within the first 24 hours after admission (P = .440). MRSA was more prevalent on the ICU over the burns unit (P = .023). Pseudomonas aeruginosa (PAER) was significantly more prevalent in military inpatients over civilian inpatients (P < .001), and on the ICU over the burns unit and wards (P = .018). Stage 1 generated a comprehensive, up to date cross section of bacterial flora, with corresponding percentage antibiotic sensitivities, in a regional burns and plastic surgery centre. This will give clinicians a snapshot of organisms affecting inpatient wounds in advance of

  8. Relative Efficiencies of a Three-Stage Versus a Two-Stage Sample Design For a New NLS Cohort Study. 22U-884-38.

    Science.gov (United States)

    Folsom, R. E.; Weber, J. H.

    Two sampling designs were compared for the planned 1978 national longitudinal survey of high school seniors with respect to statistical efficiency and cost. The 1972 survey used a stratified two-stage sample of high schools and seniors within schools. In order to minimize interviewer travel costs, an alternate sampling design was proposed,…

  9. Two stages of economic development

    OpenAIRE

    Gong, Gang

    2016-01-01

    This study suggests that the development process of a less-developed country can be divided into two stages, which demonstrate significantly different properties in areas such as structural endowments, production modes, income distribution, and the forces that drive economic growth. The two stages of economic development have been indicated in the growth theory of macroeconomics and in the various "turning point" theories in development economics, including Lewis's dual economy theory, Kuznet...

  10. A Study of a Two Stage Maximum Power Point Tracking Control of a Photovoltaic System under Partially Shaded Insolation Conditions

    Science.gov (United States)

    Kobayashi, Kenji; Takano, Ichiro; Sawada, Yoshio

    A photovoltaic array shows relatively low output power density, and has a greatly drooping Current-Voltage (I-V) characteristic. Therefore, Maximum Power Point Tracking (MPPT) control is used to maximize the output power of the array. Many papers have been reported in relation to MPPT. However, the Current-Power (I-P) curve sometimes shows multi-local maximum points mode under non-uniform insolation conditions. The operating point of the PV system tends to converge to a local maximum output point which is not the real maximal output point on the I-P curve. Some papers have been also reported, trying to avoid this difficulty. However most of those control systems become rather complicated. Then, the two stage MPPT control method is proposed in this paper to realize a relatively simple control system which can track the real maximum power point even under non-uniform insolation conditions. The feasibility of this control concept is confirmed for steady insolation as well as for rapidly changing insolation by simulation study using software PSIM and LabVIEW. In addition, simulated experiment confirms fundament al operation of the two stage MPPT control.

  11. A comprehensive study of task coalescing for selecting parallelism granularity in a two-stage bidiagonal reduction

    KAUST Repository

    Haidar, Azzam

    2012-05-01

    We present new high performance numerical kernels combined with advanced optimization techniques that significantly increase the performance of parallel bidiagonal reduction. Our approach is based on developing efficient fine-grained computational tasks as well as reducing overheads associated with their high-level scheduling during the so-called bulge chasing procedure that is an essential phase of a scalable bidiagonalization procedure. In essence, we coalesce multiple tasks in a way that reduces the time needed to switch execution context between the scheduler and useful computational tasks. At the same time, we maintain the crucial information about the tasks and their data dependencies between the coalescing groups. This is the necessary condition to preserve numerical correctness of the computation. We show our annihilation strategy based on multiple applications of single orthogonal reflectors. Despite non-trivial characteristics in computational complexity and memory access patterns, our optimization approach smoothly applies to the annihilation scenario. The coalescing positively influences another equally important aspect of the bulge chasing stage: the memory reuse. For the tasks within the coalescing groups, the data is retained in high levels of the cache hierarchy and, as a consequence, operations that are normally memory-bound increase their ratio of computation to off-chip communication and become compute-bound which renders them amenable to efficient execution on multicore architectures. The performance for the new two-stage bidiagonal reduction is staggering. Our implementation results in up to 50-fold and 12-fold improvement (∼130 Gflop/s) compared to the equivalent routines from LAPACK V3.2 and Intel MKL V10.3, respectively, on an eight socket hexa-core AMD Opteron multicore shared-memory system with a matrix size of 24000 x 24000. Last but not least, we provide a comprehensive study on the impact of the coalescing group size in terms of cache

  12. A Two-Stage Penalized Logistic Regression Approach to Case-Control Genome-Wide Association Studies

    Directory of Open Access Journals (Sweden)

    Jingyuan Zhao

    2012-01-01

    Full Text Available We propose a two-stage penalized logistic regression approach to case-control genome-wide association studies. This approach consists of a screening stage and a selection stage. In the screening stage, main-effect and interaction-effect features are screened by using L1-penalized logistic like-lihoods. In the selection stage, the retained features are ranked by the logistic likelihood with the smoothly clipped absolute deviation (SCAD penalty (Fan and Li, 2001 and Jeffrey’s Prior penalty (Firth, 1993, a sequence of nested candidate models are formed, and the models are assessed by a family of extended Bayesian information criteria (J. Chen and Z. Chen, 2008. The proposed approach is applied to the analysis of the prostate cancer data of the Cancer Genetic Markers of Susceptibility (CGEMS project in the National Cancer Institute, USA. Simulation studies are carried out to compare the approach with the pair-wise multiple testing approach (Marchini et al. 2005 and the LASSO-patternsearch algorithm (Shi et al. 2007.

  13. A study of a two stage maximum power point tracking control of a photovoltaic system under partially shaded insolation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Kenji; Takano, Ichiro; Sawada, Yoshio [Kogakuin University, Tokyo 163-8677 (Japan)

    2006-11-23

    A photovoltaic (PV) array shows relatively low output power density, and has a greatly drooping current-voltage (I-V) characteristic. Therefore, maximum power point tracking (MPPT) control is used to maximize the output power of the PV array. Many papers have been reported in relation to MPPT. However, the current-power (I-P) curve sometimes shows multi-local maximum point mode under non-uniform insolation conditions. The operating point of the PV system tends to converge to a local maximum output point which is not the real maximal output point on the I-P curve. Some papers have been also reported, trying to avoid this difficulty. However, most of those control systems become rather complicated. Then, the two stage MPPT control method is proposed in this paper to realize a relatively simple control system which can track the real maximum power point even under non-uniform insolation conditions. The feasibility of this control concept is confirmed for steady insolation as well as for rapidly changing insolation by simulation study using software PSIM and LabVIEW. (author)

  14. A study of the process of two staged anaerobic fermentation as a possible method for purifying sewage

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Y; Kouama, K; Matsuo, T

    1983-01-01

    Great attention has recently been given to the study of the processes of anaerobic fermentation, which may become alternatives to the existing methods for purifying waste waters which use aerobic microorganisms. A series of experimentswere conducted with the use of an artificially prepared liquid (fermented milk and starch) which imitates the waste to be purified, in order to explain the capabilities of the process of two staged anaerobic fermentation (DAS) as a method for purifying waste waters. The industrial system of the process includes: a fermentation vat for acetic fermentation with recirculation of the sediment, a primary settler, a fermentation tank for methane fermentation and a secondary settler. The process was conducted at a loading speed (based on Carbon) from 0.15 to 0.4 kilograms per cubic meter per day at a temperature of 38C. The degree of conversion of the fermented organic substances into volatile organic acids was not a function of the loading speed and was 54 to 57 percent in the acetic fermentation tank, where 95 to 97 percent of the organic material was broken down with the production of methane and carbon dioxide.

  15. Experimental study on an innovative multifunction heat pipe type heat recovery two-stage sorption refrigeration system

    International Nuclear Information System (INIS)

    Li, T.X.; Wang, R.Z.; Wang, L.W.; Lu, Z.S.

    2008-01-01

    An innovative multifunction heat pipe type sorption refrigeration system is designed, in which a two-stage sorption thermodynamic cycle based on two heat recovery processes was employed to reduce the driving heat source temperature, and the composite sorbent of CaCl 2 and activated carbon was used to improve the mass and heat transfer performances. For this test unit, the heating, cooling and heat recovery processes between two reactive beds are performed by multifunction heat pipes. The aim of this paper is to investigate the cycled characteristics of two-stage sorption refrigeration system with heat recovery processes. The two sub-cycles of a two-stage cycle have different sorption platforms though the adsorption and desorption temperatures are equivalent. The experimental results showed that the pressure evolutions of two beds are nearly equivalent during the first stage, and desorption pressure during the second stage is large higher than that in the first stage while the desorption temperatures are same during the two operation stages. In comparison with conventional two-stage cycle, the two-stage cycle with heat recovery processes can reduce the heating load for desorber and cooling load for adsorber, the coefficient of performance (COP) has been improved more than 23% when both cycles have the same regeneration temperature of 103 deg. C and the cooling water temperature of 30 deg. C. The advanced two-stage cycle provides an effective method for application of sorption refrigeration technology under the condition of low-grade temperature heat source or utilization of renewable energy

  16. A two-stage epidemiological study of eating disorders and muscle dysmorphia in male university students in Buenos Aires.

    Science.gov (United States)

    Compte, Emilio J; Sepulveda, Ana R; Torrente, Fernando

    2015-12-01

    Studies using traditional screening instruments tend to report a lower prevalence of eating disorders (EDs) in men than is observed in women. It is therefore unclear whether such instruments are valid for the assessment of ED in males. Lack of a formal diagnostic definition of muscle dysmorphia syndrome (MD) makes it difficult to identify men at risk. The study aimed to assess the prevalence of ED and MD in male university students of Buenos Aires. A cross-sectional, two-stage, representative survey was of 472 male students from six different schools in Buenos Aires, mostly aged between 18 and 28 years. The first stage involved administration of self-report questionnaires (Eating Attitude Test-26; scores ≥15 indicate "at risk" status). In Stage 2 students at risk of developing EDs were evaluated with a clinical interview, the Eating Disorder Examination (EDE; 12th edition). Two control students were interviewed for every at risk student. The prevalence of EDs among university male students was 1.9% (n = 9). All participants with an ED presented with illness classified as eating disorder not otherwise specified (EDNOS). Using the Drive for Muscularity Scale (DMS) with a 52-point threshold we identified possible MD in 6.99% (n = 33) of the sample. The prevalence of ED detected in this study is comparable with previous findings in male populations, and below that observed in female populations. However, the prevalence of possible cases of MD resembles the total rate of EDs in women. Characteristics associated with EDs and MD in men are also discussed. © 2015 Wiley Periodicals, Inc.

  17. Genetic variants at 1p11.2 and breast cancer risk: a two-stage study in Chinese women.

    Directory of Open Access Journals (Sweden)

    Yue Jiang

    Full Text Available BACKGROUND: Genome-wide association studies (GWAS have identified several breast cancer susceptibility loci, and one genetic variant, rs11249433, at 1p11.2 was reported to be associated with breast cancer in European populations. To explore the genetic variants in this region associated with breast cancer in Chinese women, we conducted a two-stage fine-mapping study with a total of 1792 breast cancer cases and 1867 controls. METHODOLOGY/PRINCIPAL FINDINGS: Seven single nucleotide polymorphisms (SNPs including rs11249433 in a 277 kb region at 1p11.2 were selected and genotyping was performed by using TaqMan® OpenArray™ Genotyping System for stage 1 samples (878 cases and 900 controls. In stage 2 (914 cases and 967 controls, three SNPs (rs2580520, rs4844616 and rs11249433 were further selected and genotyped for validation. The results showed that one SNP (rs2580520 located at a predicted enhancer region of SRGAP2 was consistently associated with a significantly increased risk of breast cancer in a recessive genetic model [Odds Ratio (OR  =  1.66, 95% confidence interval (CI  =  1.16-2.36 for stage 2 samples; OR  =  1.51, 95% CI  =  1.16-1.97 for combined samples, respectively]. However, no significant association was observed between rs11249433 and breast cancer risk in this Chinese population (dominant genetic model in combined samples: OR  =  1.20, 95% CI  =  0.92-1.57. CONCLUSIONS/SIGNIFICANCE: Genotypes of rs2580520 at 1p11.2 suggest that Chinese women may have different breast cancer susceptibility loci, which may contribute to the development of breast cancer in this population.

  18. High performance work systems and employee well-being: a two stage study of a rural Australian hospital.

    Science.gov (United States)

    Young, Suzanne; Bartram, Timothy; Stanton, Pauline; Leggat, Sandra G

    2010-01-01

    This paper aims to explore the attitudes of managers and employees to high performance work practices (HPWS) in a medium sized rural Australian hospital. The study consists of two stages. Stage one involved a qualitative investigation consisting of interviews and focus group sessions with senior, middle and line management at the hospital. Bowen and Ostroffs framework was used to examine how strategic HRM was understood, interpreted and operationalised across the management hierarchy. Stage one investigates the views of managers concerning the implementation of strategic HRM/HPWS. Stage two consisted of a questionnaire administered to all hospital employees. The mediation effects of social identification on the relationship between high performance work systems and affective commitment and job satisfaction are examined. The purpose of stage two was to investigate the views and effects of SHRM/HPWS on employees. It should be noted that HPWS and strategic HRM are used inter-changeably in this paper. At the management level the importance of distinctiveness, consistency and consensus in the interpretation of strategic HRM/HPWS practices across the organization was discovered. Findings indicate that social identification mediates the relationship between HPWS and affective commitment and also mediates the relationship between HPWS and job satisfaction. High performance work systems may play a crucial role facilitating social identification at the unit level. Such practices and management support is likely to provide benefits in terms of high performing committed employees. The paper argues that team leaders and managers play a key role in building social identification within the team and that organizations need to understand this role and provide recognition, reward, education and support to their middle and lower managers.

  19. Study of shallow junction formation by boron-containing cluster ion implantation of silicon and two-stage annealing

    Science.gov (United States)

    Lu, Xin-Ming

    Shallow junction formation made by low energy ion implantation and rapid thermal annealing is facing a major challenge for ULSI (ultra large scale integration) as the line width decreases down to the sub micrometer region. The issues include low beam current, the channeling effect in low energy ion implantation and TED (transient enhanced diffusion) during annealing after ion implantation. In this work, boron containing small cluster ions, such as GeB, SiB and SiB2, was generated by using the SNICS (source of negative ion by cesium sputtering) ion source to implant into Si substrates to form shallow junctions. The use of boron containing cluster ions effectively reduces the boron energy while keeping the energy of the cluster ion beam at a high level. At the same time, it reduces the channeling effect due to amorphization by co-implanted heavy atoms like Ge and Si. Cluster ions have been used to produce 0.65--2keV boron for low energy ion implantation. Two stage annealing, which is a combination of low temperature (550°C) preannealing and high temperature annealing (1000°C), was carried out to anneal the Si sample implanted by GeB, SiBn clusters. The key concept of two-step annealing, that is, the separation of crystal regrowth, point defects removal with dopant activation from dopant diffusion, is discussed in detail. The advantages of the two stage annealing include better lattice structure, better dopant activation and retarded boron diffusion. The junction depth of the two stage annealed GeB sample was only half that of the one-step annealed sample, indicating that TED was suppressed by two stage annealing. Junction depths as small as 30 nm have been achieved by two stage annealing of sample implanted with 5 x 10-4/cm2 of 5 keV GeB at 1000°C for 1 second. The samples were evaluated by SIMS (secondary ion mass spectrometry) profiling, TEM (transmission electron microscopy) and RBS (Rutherford Backscattering Spectrometry)/channeling. Cluster ion implantation

  20. Two-stage implant systems.

    Science.gov (United States)

    Fritz, M E

    1999-06-01

    Since the advent of osseointegration approximately 20 years ago, there has been a great deal of scientific data developed on two-stage integrated implant systems. Although these implants were originally designed primarily for fixed prostheses in the mandibular arch, they have been used in partially dentate patients, in patients needing overdentures, and in single-tooth restorations. In addition, this implant system has been placed in extraction sites, in bone-grafted areas, and in maxillary sinus elevations. Often, the documentation of these procedures has lagged. In addition, most of the reports use survival criteria to describe results, often providing overly optimistic data. It can be said that the literature describes a true adhesion of the epithelium to the implant similar to adhesion to teeth, that two-stage implants appear to have direct contact somewhere between 50% and 70% of the implant surface, that the microbial flora of the two-stage implant system closely resembles that of the natural tooth, and that the microbiology of periodontitis appears to be closely related to peri-implantitis. In evaluations of the data from implant placement in all of the above-noted situations by means of meta-analysis, it appears that there is a strong case that two-stage dental implants are successful, usually showing a confidence interval of over 90%. It also appears that the mandibular implants are more successful than maxillary implants. Studies also show that overdenture therapy is valid, and that single-tooth implants and implants placed in partially dentate mouths have a success rate that is quite good, although not quite as high as in the fully edentulous dentition. It would also appear that the potential causes of failure in the two-stage dental implant systems are peri-implantitis, placement of implants in poor-quality bone, and improper loading of implants. There are now data addressing modifications of the implant surface to alter the percentage of

  1. Experimental study on two-stage compression refrigeration/heat pump system with dual-cylinder rolling piston compressor

    International Nuclear Information System (INIS)

    Shuxue, Xu; Guoyuan, Ma

    2014-01-01

    A thermodynamically analytical model on the two-stage compression refrigeration/heat pump system with vapor injection was derived. The optimal volume ratio of the high-pressure cylinder to the low-pressure one has been discussed under both cooling and heating conditions. Based on the above research, the prototype was developed and its experimental setup established. A comprehensive experiments for the prototype have been conducted, and the results show that, compared with the single-stage compression heat pump system, the cooling capacity and cooling COP can increase 5%–15% and 10–12%, respectively. Also, the heating capacity with the evaporating temperature ranging from 0.3 to 3 °C is 92–95% of that under the rate condition with the evaporating temperature of 7 °C, and 58% when the evaporation temperature is between −28 °C and −24 °C. -- Highlights: • The volume ratio of the compressor is between 0.65 and 0.78 and the relative vapor injection mass ranges from 15% to 20%. • The cooling capacity and COP of the two-stage compression system can improve 5%–15% and 10%–12%. • The heating capacity can also be improved under low temperature condition

  2. Parametric study of two-stage hydropyrolysis of lignocellulosic biomass for production of gaseous and light aromatic hydrocarbons.

    Science.gov (United States)

    Zheng, Nan; Zhang, Jie; Wang, Jie

    2017-11-01

    Non-catalytic hydropyrolysis of pinewood and its components was carried out using a two-stage reactor. The main aim of this work is to investigate the hydrodeoxygenation and hydrogenation of volatile matter in the post hydrocracking reactor for oriented production of gaseous and light aromatic hydrocarbons. A portion of volatile matter, which evolved from hemicellulose, neutral extractives and lignin below 275°C, was found to be thoroughly hydrodeoxygenated preventing the release of CO 2 and CO. Increasing hydrocracking temperature from 600°C to 750°C and pressure from 1.0MPa to 5.0MPa strongly facilitated the hydrogenation reactions to target products. The summed yield of CH 4 and C 2 H 6 (dry biomass basis) reached up to 33.2% at a hydrocracking temperature of 750°C and 5.0MPa, with a concomitant 5.1% yield of BTX. All components in pinewood significantly contributed to the production of CH 4 and BTX by hydropyrolysis, differing from the case of pyrolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Intramedullary stabilization and over-nail lengthening as two-stage treatment of femoral nonunion with shortening. Case study.

    Science.gov (United States)

    Kącki, Wojciech; Jasiewicz, Barbara; Radło, Paweł

    2014-01-01

    Nonunion is one of the most serious complications of long bone fractures. It may be accompanied by a shortening of the segment. The authors describe the case of a 21-year-old woman with a post-traumatic nonunion with shortening of the femur. Treatment was divided into two stages: first, a previously placed nail was removed and new intramedullary stabilization was carried out while bone defects were filled with a bone graft substitute and platelet rich plasma was administered. After the nonunion had healed, the femur was lengthened over an external fixator and an intramedullary nail, resulting in equality of limb length. After eight years of follow-up, the lower limbs remain equal with a properly aligned long axis of the lower limb operated on and a full range of motion in the joints. The treatment strategy described in our article may be an alternative to one-stage surgery if the patient does not consent to it or in the presence of contraindications, but it is associated with a longer treatment time and necessity of additional surgeries.

  4. Adjusting for treatment switching in randomised controlled trials - A simulation study and a simplified two-stage method.

    Science.gov (United States)

    Latimer, Nicholas R; Abrams, K R; Lambert, P C; Crowther, M J; Wailoo, A J; Morden, J P; Akehurst, R L; Campbell, M J

    2017-04-01

    Estimates of the overall survival benefit of new cancer treatments are often confounded by treatment switching in randomised controlled trials (RCTs) - whereby patients randomised to the control group are permitted to switch onto the experimental treatment upon disease progression. In health technology assessment, estimates of the unconfounded overall survival benefit associated with the new treatment are needed. Several switching adjustment methods have been advocated in the literature, some of which have been used in health technology assessment. However, it is unclear which methods are likely to produce least bias in realistic RCT-based scenarios. We simulated RCTs in which switching, associated with patient prognosis, was permitted. Treatment effect size and time dependency, switching proportions and disease severity were varied across scenarios. We assessed the performance of alternative adjustment methods based upon bias, coverage and mean squared error, related to the estimation of true restricted mean survival in the absence of switching in the control group. We found that when the treatment effect was not time-dependent, rank preserving structural failure time models (RPSFTM) and iterative parameter estimation methods produced low levels of bias. However, in the presence of a time-dependent treatment effect, these methods produced higher levels of bias, similar to those produced by an inverse probability of censoring weights method. The inverse probability of censoring weights and structural nested models produced high levels of bias when switching proportions exceeded 85%. A simplified two-stage Weibull method produced low bias across all scenarios and provided the treatment switching mechanism is suitable, represents an appropriate adjustment method.

  5. One- and two-stage surgical revision of peri-prosthetic joint infection of the hip: a pooled individual participant data analysis of 44 cohort studies.

    Science.gov (United States)

    Kunutsor, Setor K; Whitehouse, Michael R; Blom, Ashley W; Board, Tim; Kay, Peter; Wroblewski, B Mike; Zeller, Valérie; Chen, Szu-Yuan; Hsieh, Pang-Hsin; Masri, Bassam A; Herman, Amir; Jenny, Jean-Yves; Schwarzkopf, Ran; Whittaker, John-Paul; Burston, Ben; Huang, Ronald; Restrepo, Camilo; Parvizi, Javad; Rudelli, Sergio; Honda, Emerson; Uip, David E; Bori, Guillem; Muñoz-Mahamud, Ernesto; Darley, Elizabeth; Ribera, Alba; Cañas, Elena; Cabo, Javier; Cordero-Ampuero, José; Redó, Maria Luisa Sorlí; Strange, Simon; Lenguerrand, Erik; Gooberman-Hill, Rachael; Webb, Jason; MacGowan, Alasdair; Dieppe, Paul; Wilson, Matthew; Beswick, Andrew D

    2018-04-05

    One-stage and two-stage revision strategies are the two main options for treating established chronic peri-prosthetic joint infection (PJI) of the hip; however, there is uncertainty regarding which is the best treatment option. We aimed to compare the risk of re-infection between the two revision strategies using pooled individual participant data (IPD). Observational cohort studies with PJI of the hip treated exclusively by one- or two-stage revision and reporting re-infection outcomes were retrieved by searching MEDLINE, EMBASE, Web of Science, The Cochrane Library, and the WHO International Clinical Trials Registry Platform; as well as email contact with investigators. We analysed IPD of 1856 participants with PJI of the hip from 44 cohorts across four continents. The primary outcome was re-infection (recurrence of infection by the same organism(s) and/or re-infection with a new organism(s)). Hazard ratios (HRs) for re-infection were calculated using Cox proportional frailty hazards models. After a median follow-up of 3.7 years, 222 re-infections were recorded. Re-infection rates per 1000 person-years of follow-up were 16.8 (95% CI 13.6-20.7) and 32.3 (95% CI 27.3-38.3) for one-stage and two-stage strategies respectively. The age- and sex-adjusted HR of re-infection for two-stage revision was 1.70 (0.58-5.00) when compared with one-stage revision. The association remained consistently absent after further adjustment for potential confounders. The HRs did not vary importantly in clinically relevant subgroups. Analysis of pooled individual patient data suggest that a one-stage revision strategy may be as effective as a two-stage revision strategy in treating PJI of the hip.

  6. Combining evidence from multiple electronic health care databases: performances of one-stage and two-stage meta-analysis in matched case-control studies.

    Science.gov (United States)

    La Gamba, Fabiola; Corrao, Giovanni; Romio, Silvana; Sturkenboom, Miriam; Trifirò, Gianluca; Schink, Tania; de Ridder, Maria

    2017-10-01

    Clustering of patients in databases is usually ignored in one-stage meta-analysis of multi-database studies using matched case-control data. The aim of this study was to compare bias and efficiency of such a one-stage meta-analysis with a two-stage meta-analysis. First, we compared the approaches by generating matched case-control data under 5 simulated scenarios, built by varying: (1) the exposure-outcome association; (2) its variability among databases; (3) the confounding strength of one covariate on this association; (4) its variability; and (5) the (heterogeneous) confounding strength of two covariates. Second, we made the same comparison using empirical data from the ARITMO project, a multiple database study investigating the risk of ventricular arrhythmia following the use of medications with arrhythmogenic potential. In our study, we specifically investigated the effect of current use of promethazine. Bias increased for one-stage meta-analysis with increasing (1) between-database variance of exposure effect and (2) heterogeneous confounding generated by two covariates. The efficiency of one-stage meta-analysis was slightly lower than that of two-stage meta-analysis for the majority of investigated scenarios. Based on ARITMO data, there were no evident differences between one-stage (OR = 1.50, CI = [1.08; 2.08]) and two-stage (OR = 1.55, CI = [1.12; 2.16]) approaches. When the effect of interest is heterogeneous, a one-stage meta-analysis ignoring clustering gives biased estimates. Two-stage meta-analysis generates estimates at least as accurate and precise as one-stage meta-analysis. However, in a study using small databases and rare exposures and/or outcomes, a correct one-stage meta-analysis becomes essential. Copyright © 2017 John Wiley & Sons, Ltd.

  7. Two-stage revision surgery with preformed spacers and cementless implants for septic hip arthritis: a prospective, non-randomized cohort study

    Directory of Open Access Journals (Sweden)

    Logoluso Nicola

    2011-05-01

    Full Text Available Abstract Background Outcome data on two-stage revision surgery for deep infection after septic hip arthritis are limited and inconsistent. This study presents the medium-term results of a new, standardized two-stage arthroplasty with preformed hip spacers and cementless implants in a consecutive series of adult patients with septic arthritis of the hip treated according to a same protocol. Methods Nineteen patients (20 hips were enrolled in this prospective, non-randomized cohort study between 2000 and 2008. The first stage comprised femoral head resection, debridement, and insertion of a preformed, commercially available, antibiotic-loaded cement hip spacer. After eradication of infection, a cementless total hip arthroplasty was implanted in the second stage. Patients were assessed for infection recurrence, pain (visual analog scale [VAS] and hip joint function (Harris Hip score. Results The mean time between first diagnosis of infection and revision surgery was 5.8 ± 9.0 months; the average duration of follow up was 56.6 (range, 24 - 104 months; all 20 hips were successfully converted to prosthesis an average 22 ± 5.1 weeks after spacer implantation. Reinfection after total hip joint replacement occurred in 1 patient. The mean VAS pain score improved from 48 (range, 35 - 84 pre-operatively to 18 (range, 0 - 38 prior to spacer removal and to 8 (range, 0 - 15 at the last follow-up assessment after prosthesis implantation. The average Harris Hip score improved from 27.5 before surgery to 61.8 between the two stages to 92.3 at the final follow-up assessment. Conclusions Satisfactory outcomes can be obtained with two-stage revision hip arthroplasty using preformed spacers and cementless implants for prosthetic hip joint infections of various etiologies.

  8. Two stage-type railgun accelerator

    International Nuclear Information System (INIS)

    Ogino, Mutsuo; Azuma, Kingo.

    1995-01-01

    The present invention provides a two stage-type railgun accelerator capable of spiking a flying body (ice pellet) formed by solidifying a gaseous hydrogen isotope as a fuel to a thermonuclear reactor at a higher speed into a central portion of plasmas. Namely, the two stage-type railgun accelerator accelerates the flying body spiked from a initial stage accelerator to a portion between rails by Lorentz force generated when electric current is supplied to the two rails by way of a plasma armature. In this case, two sets of solenoids are disposed for compressing the plasma armature in the longitudinal direction of the rails. The first and the second sets of solenoid coils are previously supplied with electric current. After passing of the flying body, the armature formed into plasmas by a gas laser disposed at the back of the flying body is compressed in the longitudinal direction of the rails by a magnetic force of the first and the second sets of solenoid coils to increase the plasma density. A current density is also increased simultaneously. Then, the first solenoid coil current is turned OFF to accelerate the flying body in two stages by the compressed plasma armature. (I.S.)

  9. A new powerful non-parametric two-stage approach for testing multiple phenotypes in family-based association studies

    NARCIS (Netherlands)

    Lange, C; Lyon, H; DeMeo, D; Raby, B; Silverman, EK; Weiss, ST

    2003-01-01

    We introduce a new powerful nonparametric testing strategy for family-based association studies in which multiple quantitative traits are recorded and the phenotype with the strongest genetic component is not known prior to the analysis. In the first stage, using a population-based test based on the

  10. Effects of Two-stage Heat Treatment on Delayed Coke and Study of Their Surface Texture Characteristics

    Science.gov (United States)

    Im, Ui-Su; Kim, Jiyoung; Lee, Seon Ho; Lee, Byung-Rok; Peck, Dong-Hyun; Jung, Doo-Hwan

    2017-12-01

    In the present study, surface texture features and chemical properties of two types of cokes, made from coal tar by either 1-stage heat treatment or 2-stage heat treatment, were researched. The relationship between surface texture characteristics and the chemical properties was identified through molecular weight distribution, insolubility of coal tar, weight loss with temperature increase, coking yield, and polarized light microscope analysis. Rapidly cleared anisotropy texture in cokes was observed in accordance with the coking temperature rise. Quinoline insolubility and toluene insolubility of coal tar increased with a corresponding increases in coking temperature. In particular, the cokes produced by the 2-stage heat treatment (2S-C) showed surface structure of needle cokes at a temperature approximately 50°C lower than the 1-stage heat treatment (1S-C). Additionally, the coking yield of 2S-C increased by approximately 14% in comparison with 1S-C.

  11. Effectiveness of medicines authentication technology to detect counterfeit, recalled and expired medicines: a two-stage quantitative secondary care study

    Science.gov (United States)

    Naughton, Bernard; Roberts, Lindsey; Dopson, Sue; Chapman, Stephen; Brindley, David

    2016-01-01

    Objectives To identify the authentication and detection rate of serialised medicines using medicines authentication technology. Design and intervention 4192 serialised medicines were entered into a hospital dispensary over two separate 8-week stages in 2015. Medicines were authenticated using secure external database cross-checking, triggered by the scanning of a two-dimensional data matrix with a unit specific 12-digit serial code. 4% of medicines included were preprogrammed with a message to identify the product as either expired, pack recalled, product recalled or counterfeit. Setting A site within a large UK National Health Service teaching hospital trust. Participants Accredited checking staff, pharmacists and dispensers in a pharmacy department. Primary outcome measures Authentication and detection rate of counterfeit expired and recalled medicines. Results The operational detection rate of counterfeit, recalled and expired medicines scanned as a combined group was 81.4% (stage 1 (S1)) and 87% (stage 2 (S2)). The technology's technical detection rate (TDR) was 100%; however, not all medicines were scanned and of those that were scanned not all that generated a warning message were quarantined. Owing to an operational authentication rate (OAR) of 66.3% (over both stages), only 31.8% of counterfeit medicines, 58% of recalled drugs and 64% of expired medicines were detected as a proportion of those entered into the study. Response times (RTs) of 152 ms (S1) and 165 ms (S2) were recorded, meeting the falsified medicines directive-mandated 300 ms limit. Conclusions TDRs and RTs were not a limiting factor in this study. The suboptimal OAR poses significant quality and safety issues with this detection approach. Authentication at the checking stage, however, demonstrated higher OARs. There is a need for further qualitative research to establish the reasons for less than absolute authentication and detection rates in the hospital environment to improve this

  12. Statistical study of clone survival curves after irradiation in one or two stages. Comparison and generalization of different models

    International Nuclear Information System (INIS)

    Lachet, Bernard.

    1975-01-01

    A statistical study was carried out on 208 survival curves for chlorella subjected to γ or particle radiations. The computing programmes used were written in Fortran. The different experimental causes contributing to the variance of a survival rate are analyzed and consequently the experiments can be planned. Each curve was fitted to four models by the weighted least squares method applied to non-linear functions. The validity of the fits obtained can be checked by the F test. It was possible to define the confidence and prediction zones around an adjusted curve by weighting of the residual variance, in spite of error on the doses delivered; the confidence limits can them be fixed for a dose estimated from an exact or measured survival. The four models adopted were compared for the precision of their fit (by a non-parametric simultaneous comparison test) and the scattering of their adjusted parameters: Wideroe's model gives a very good fit with the experimental points in return for a scattering of its parameters, which robs them of their presumed meaning. The principal component analysis showed the statistical equivalence of the 1 and 2 hit target models. Division of the irradiation into two doses, the first fixed by the investigator, leads to families of curves for which the equation was established from that of any basic model expressing the dose survival relationship in one-stage irradiation [fr

  13. Mental health problems in Austrian adolescents: a nationwide, two-stage epidemiological study applying DSM-5 criteria.

    Science.gov (United States)

    Wagner, Gudrun; Zeiler, Michael; Waldherr, Karin; Philipp, Julia; Truttmann, Stefanie; Dür, Wolfgang; Treasure, Janet L; Karwautz, Andreas F K

    2017-12-01

    This is a nationwide epidemiological study using DSM-5 criteria to assess the prevalence of mental disorders in a large sample of Austrian adolescents between 10 and 18 years including hard-to-reach samples. A sample of 3615 adolescents from four cohorts (school grades 5, 7, 9, 11; age range 10-18 years) was recruited from 261 schools, samples of unemployed adolescents (n = 39) and adolescents from mental health institutions (n = 137) were added. The Youth Self-Report and SCOFF were used to screen for mental health problems. In a second phase, the Childrens' Diagnostic Interview for Mental Disorders was used to make point and lifetime psychiatric diagnoses. Mental health service use was also assessed. Point prevalence and lifetime prevalence rates for at least one psychiatric disorder were 23.9% and 35.8%. The highest lifetime prevalence rates were found for anxiety disorders (15.6%), neurodevelopmental disorders (9.3%; ADHD 5.2%) and depressive disorders (6.2%). Forty-seven percent of adolescents with a lifetime psychiatric disorder had a second diagnosis. Internalising disorders were more prevalent in girls, while neurodevelopmental disorders and disruptive, impulse control and conduct disorders were more prevalent in boys. Of those with a lifetime psychiatric disorder, 47.5% had contacted mental health services. Of the residual 52.5% who had not contacted mental health services, 18.1% expressed an interest in treatment. DSM-5 mental health disorders are highly prevalent among Austrian adolescents. Over 50% had or were interested in accessing treatment. Early access to effective interventions for these problems is needed to reduce burden due to mental health disorders.

  14. Polymorphisms in CARS are associated with gastric cancer risk: a two-stage case-control study in the Chinese population.

    Science.gov (United States)

    Tian, Tian; Xiao, Ling; Du, Jiangbo; Zhu, Xun; Gu, Yayun; Qin, Na; Yan, Caiwang; Liu, Li; Ma, Hongxia; Jiang, Yue; Chen, Jiaping; Yu, Hao; Dai, Juncheng

    2017-11-01

    The cysteinyl transfer RNA synthetase gene (CARS) is located on chromosome band 11p15.5, which is an important tumor-suppressor gene region. Mutations in CARS have been identified in many kinds of cancers; however, evidence for a relationship between genetic variants in CARS and gastric cancer at the population level is still lacking. Thus, we explored the association of variants in CARS with gastric cancer using a two-stage case-control strategy in Chinese. We undertook a two-stage case-control study to investigate the association between polymorphisms in CARS and risk of gastric cancer with use of an Illumina Infinium ® BeadChip and an ABI 7900 system. Four single nucleotide polymorphisms (SNPs) were significantly associated with gastric cancer risk in both the discovery stage and the validation stage after adjustment for age and sex. In addition, the combined results of the two stages showed these SNPs were related to gastric cancer risk (P false discovery rate  ≤ 0.001 for rs384,490, rs729662, rs2071101, and rs7394702). In silico analyses revealed that rs384490 and rs7394702 could affect transcription factor response elements or DNA methylation of CARS, and rs729662 was associated with the prognosis of gastric cancer. Additionally, expression quantitative trait loci analysis showed rs384490 and rs729662 might alter expression of CARS-related genes. The potential functional SNPs in CARS might influence the biological functions of CARS or CARS-related genes and ultimately modify the occurrence and development of gastric cancer in Chinese. Further large-scale population-based studies or biological functional assays are warranted to validate our findings.

  15. One-stage or two-stage revision surgery for prosthetic hip joint infection--the INFORM trial: a study protocol for a randomised controlled trial.

    Science.gov (United States)

    Strange, Simon; Whitehouse, Michael R; Beswick, Andrew D; Board, Tim; Burston, Amanda; Burston, Ben; Carroll, Fran E; Dieppe, Paul; Garfield, Kirsty; Gooberman-Hill, Rachael; Jones, Stephen; Kunutsor, Setor; Lane, Athene; Lenguerrand, Erik; MacGowan, Alasdair; Moore, Andrew; Noble, Sian; Simon, Joanne; Stockley, Ian; Taylor, Adrian H; Toms, Andrew; Webb, Jason; Whittaker, John-Paul; Wilson, Matthew; Wylde, Vikki; Blom, Ashley W

    2016-02-17

    Periprosthetic joint infection (PJI) affects approximately 1% of patients following total hip replacement (THR) and often results in severe physical and emotional suffering. Current surgical treatment options are debridement, antibiotics and implant retention; revision THR; excision of the joint and amputation. Revision surgery can be done as either a one-stage or two-stage operation. Both types of surgery are well-established practice in the NHS and result in similar rates of re-infection, but little is known about the impact of these treatments from the patient's perspective. The main aim of this randomised controlled trial is to determine whether there is a difference in patient-reported outcome measures 18 months after randomisation for one-stage or two-stage revision surgery. INFORM (INFection ORthopaedic Management) is an open, two-arm, multi-centre, randomised, superiority trial. We aim to randomise 148 patients with eligible PJI of the hip from approximately seven secondary care NHS orthopaedic units from across England and Wales. Patients will be randomised via a web-based system to receive either a one-stage revision or a two-stage revision THR. Blinding is not possible due to the nature of the intervention. All patients will be followed up for 18 months. The primary outcome is the WOMAC Index, which assesses hip pain, function and stiffness, collected by questionnaire at 18 months. Secondary outcomes include the following: cost-effectiveness, complications, re-infection rates, objective hip function assessment and quality of life. A nested qualitative study will explore patients' and surgeons' experiences, including their views about trial participation and randomisation. INFORM is the first ever randomised trial to compare two widely accepted surgical interventions for the treatment of PJI: one-stage and two-stage revision THR. The results of the trial will benefit patients in the future as the main focus is on patient-reported outcomes: pain, function

  16. Dynamic Modeling and Control Studies of a Two-Stage Bubbling Fluidized Bed Adsorber-Reactor for Solid-Sorbent CO{sub 2} Capture

    Energy Technology Data Exchange (ETDEWEB)

    Modekurti, Srinivasarao; Bhattacharyya, Debangsu; Zitney, Stephen E.

    2013-07-31

    A one-dimensional, non-isothermal, pressure-driven dynamic model has been developed for a two-stage bubbling fluidized bed (BFB) adsorber-reactor for solid-sorbent carbon dioxide (CO{sub 2}) capture using Aspen Custom Modeler® (ACM). The BFB model for the flow of gas through a continuous phase of downward moving solids considers three regions: emulsion, bubble, and cloud-wake. Both the upper and lower reactor stages are of overflow-type configuration, i.e., the solids leave from the top of each stage. In addition, dynamic models have been developed for the downcomer that transfers solids between the stages and the exit hopper that removes solids from the bottom of the bed. The models of all auxiliary equipment such as valves and gas distributor have been integrated with the main model of the two-stage adsorber reactor. Using the developed dynamic model, the transient responses of various process variables such as CO{sub 2} capture rate and flue gas outlet temperatures have been studied by simulating typical disturbances such as change in the temperature, flowrate, and composition of the incoming flue gas from pulverized coal-fired power plants. In control studies, the performance of a proportional-integral-derivative (PID) controller, feedback-augmented feedforward controller, and linear model predictive controller (LMPC) are evaluated for maintaining the overall CO{sub 2} capture rate at a desired level in the face of typical disturbances.

  17. A longitudinal study

    OpenAIRE

    Kristen, Astrid

    2010-01-01

    Does playing violent video games increase aggressive behavior over time or is it aggressive children who increasingly seek out (and play) these violent video games? To study such long-term effects a longitudinal design is necessary. Within a field study in a large German city (Kinder, Computer, Hobby, Lernen – KUHL, Freie Universtität Berlin) about 115 elementary school boys attending in the beginning (t1) classrooms of the third and fourth grade and twelve months later (t2) classrooms of the...

  18. Analisis Efisiensi Baitul Maal Wat Tamwil Dengan Pendekatan Two Stage Data Envelopment Analysis (Studi Kasus Kantor Cabang BMT MMU Dan BMT UGT Sidogiri

    Directory of Open Access Journals (Sweden)

    Muhammad Mahbubi Ali

    2014-03-01

    Full Text Available Penelitian ini bertujuan untuk mengukur tingkat efisiensi Baitul Maal Wat Tamwil (BMT dengan mengambil studi kasus BMT MMU dan BMT UGT Sidogiri Pasuruan tingkat cabang dengan total sampel 50 cabang. Metode yang digunakan dalam penelitian ini adalah Two Stage DEA. Tahap pertama mengukur tingkat efisiensi BMT MMU dan BMT UGT dengan menggunakan DEA. Tahap kedua menguji faktor-faktor internal dan eksternal, yang mempengaruhi tingkat efisiensi BMT MMU dan BMT UGT dengan menggunakan pendekatan Tobit. Hasil penghitungan DEA menunjukkan, efisiensi overall technical BMT MMU (0,84 dan BMT UGT (0,88 pada tahun 2008 masih kurang optimal. Penyebab utama inefisiensi untuk BMT MMU adalah penyaluran pembiayaan, sementara sumber utama inefisiensi BMT UGT adalah penghimpunan dana pihak ketiga yang kurang maksimal. Hasil pengolahan Tobit menunjukkan bahwa kekuatan modal dan ukuran BMT memiliki pengaruh positif secara signifikan terhadap efisiensi overall technical pada dua BMT. Sementara dari sisi eksternal, PDRB perkapita memiliki pengaruh negatif secara signifikan. Adapun pertumbuhan pengangguran, tingkat pendidikan, dan komitmen keberagamaan tidak berpengaruh secara signifikan.JEL Classification : G21, R15Keywords : Efisiensi, BMT, Two Stage DEA

  19. LEIR longitudinal studies

    CERN Document Server

    Albright, S; Hancock, S

    2017-01-01

    Towards the end of 2015 and during 2016 there were exten-sive studies of longitudinal beam dynamics in LEIR aimedat improving extracted intensities. As the driving source oflosses early in the ramp was shown to be transverse spacecharge tune spread a significant improvement came fromflattening the beam profile to increase the bunching factorby offsetting the RF frequency from the beam revolution fre-quency. Further benefits were provided by modulating theRF frequency during capture, leading to emittance blow-upand improved reproducibility. The use of two RF cavitiesduring operation was studied to try and further increase thecaptured emittance, however after careful alignment of theRF it was found that a hard limit in the bunch heigh of approx-imately 7 MeV exists. Due to the acceptance limit there wasno operational benefit to using both cavities simultaneously

  20. Simulation and experimental study of solar-absorption heat transformer integrating with two-stage high temperature vapor compression heat pump

    Directory of Open Access Journals (Sweden)

    Nattaporn Chaiyat

    2014-11-01

    Full Text Available In this study, simulation and experiment studies of a 10 kW solar H2O–LiBr absorption heat transformer (AHT integrating with a two-stage vapor compression heat pump (VCHP were carried out. The whole system was named as compression/absorption heat transformer (CAHT. The VCHP was used to recover rejected heat at the AHT condenser which was transferred back to the AHT evaporator at a higher temperature. The AHT unit took solar heat from a set of flat-plate solar collectors in parallel connection. R-134a and R-123 were refrigerants in the VCHP cycle. From the simulation, the total cycle coefficient (COP of the solar-CAHT was 0.71 compared with 0.49 of the normal solar-AHT. From the experiment, the total cycle COPs of the solar-CAHT and the solar-AHT were 0.62 and 0.39, respectively. The experimental results were lower than those of the simulated models due to the oversize of the experimental compressor. The annual expense of the solar-CAHT was found to be 5113 USD which was lower than 5418 USD of the solar-AHT. So it could be concluded that the modified unit was beneficial than the normal unit in terms of energy efficiency and economic expense.

  1. Multiple Genes Related to Muscle Identified through a Joint Analysis of a Two-stage Genome-wide Association Study for Racing Performance of 1,156 Thoroughbreds

    Directory of Open Access Journals (Sweden)

    Dong-Hyun Shin

    2015-06-01

    Full Text Available Thoroughbred, a relatively recent horse breed, is best known for its use in horse racing. Although myostatin (MSTN variants have been reported to be highly associated with horse racing performance, the trait is more likely to be polygenic in nature. The purpose of this study was to identify genetic variants strongly associated with racing performance by using estimated breeding value (EBV for race time as a phenotype. We conducted a two-stage genome-wide association study to search for genetic variants associated with the EBV. In the first stage of genome-wide association study, a relatively large number of markers (~54,000 single-nucleotide polymorphisms, SNPs were evaluated in a small number of samples (240 horses. In the second stage, a relatively small number of markers identified to have large effects (170 SNPs were evaluated in a much larger number of samples (1,156 horses. We also validated the SNPs related to MSTN known to have large effects on racing performance and found significant associations in the stage two analysis, but not in stage one. We identified 28 significant SNPs related to 17 genes. Among these, six genes have a function related to myogenesis and five genes are involved in muscle maintenance. To our knowledge, these genes are newly reported for the genetic association with racing performance of Thoroughbreds. It complements a recent horse genome-wide association studies of racing performance that identified other SNPs and genes as the most significant variants. These results will help to expand our knowledge of the polygenic nature of racing performance in Thoroughbreds.

  2. Performance study of a heat pump driven and hollow fiber membrane-based two-stage liquid desiccant air dehumidification system

    International Nuclear Information System (INIS)

    Zhang, Ning; Yin, Shao-You; Zhang, Li-Zhi

    2016-01-01

    Graphical abstract: A heat pump driven, hollow fiber membrane-based two-stage liquid desiccant air dehumidification system. - Highlights: • A two-stage hollow fiber membrane based air dehumidification is proposed. • It is heat pump driven liquid desiccant system. • Performance is improved 20% upon single stage system. • The optimal first to second stage dehumidification area ratio is 1.4. - Abstract: A novel compression heat pump driven and hollow fiber membrane-based two-stage liquid desiccant air dehumidification system is presented. The liquid desiccant droplets are prevented from crossing over into the process air by the semi-permeable membranes. The isoenthalpic processes are changed to quasi-isothermal processes by the two-stage dehumidification processes. The system is set up and a model is proposed for simulation. Heat and mass capacities in the system, including the membrane modules, the condenser, the evaporator and the heat exchangers are modeled in detail. The model is also validated experimentally. Compared with a single-stage dehumidification system, the two-stage system has a lower solution concentration exiting from the dehumidifier and a lower condensing temperature. Thus, a better thermodynamic system performance is realized and the COP can be increased by about 20% under the typical hot and humid conditions in Southern China. The allocations of heat and mass transfer areas in the system are also investigated. It is found that the optimal regeneration to dehumidification area ratio is 1.33. The optimal first to second stage dehumidification area ratio is 1.4; and the optimal first to second stage regeneration area ratio is 1.286.

  3. PARP-1 Variant Rs1136410 Confers Protection against Coronary Artery Disease in a Chinese Han Population: A Two-Stage Case-Control Study Involving 5643 Subjects

    Directory of Open Access Journals (Sweden)

    Xue-bin Wang

    2017-11-01

    Full Text Available Inhibition of poly(ADP-ribose polymerase (PARP may protect against coronary artery disease (CAD in animal models, and rs1136410, a non-synonymous single nucleotide polymorphism (SNP in PARP-1, has a potential impact on PARP activities in vitro. This two-stage case-control study, involving 2803 CAD patients and 2840 controls, aimed to investigate the associations of PARP-1 rs1136410 with CAD development, lipid levels, PARP activities, 8-hydroxy-2′-dexyguanosine (8-OHdG, and interleukin (IL-6 levels in a Chinese Han population. Assuming a recessive model, the variant genotype GG of SNP rs1136410 showed a significantly inverse association with CAD risk (adjusted odds ratio (OR = 0.73, P < 0.001, left main coronary artery (LMCA lesions (P = 0.003, vessel scores (P = 0.003, and modified Gensini scores (P < 0.001. There were significant correlations of SNP rs1136410 with higher levels of total cholesterol (TC and lower levels of high-density lipoprotein cholesterol (HDL-c. In gene-environment interaction analyses, participants with the variant genotype GG, but without smoking habit, type 2 diabetes mellitus, and hyperlipidemia, conferred an 84% (P < 0.001 decreased risk of CAD. The genotype-phenotype correlation analyses further supported the functional roles of SNP rs1136410 in decreasing PARP activities and 8-OHdG levels. Taken together, our data suggest that SNP rs1136410 may confer protection against CAD through modulation of PARP activities and gene-environment interactions in a Chinese Han population.

  4. Studying feasibility and effects of a two-stage nursing staff training in residential geriatric care using a 30 month mixed-methods design [ISRCTN24344776

    Directory of Open Access Journals (Sweden)

    Hantikainen Virpi

    2011-05-01

    Full Text Available Abstract Background Transfer techniques and lifting weights often cause back pain and disorders for nurses in geriatric care. The Kinaesthetics care conception claims to be an alternative, yielding benefits for nurses as well as for clients. Starting a multi-step research program on the effects of Kinaesthetics, we assess the feasibility of a two-stage nursing staff training and a pre-post research design. Using quantitative and qualitative success criteria, we address mobilisation from the bed to a chair and backwards, walking with aid and positioning in bed on the staff level as well as on the resident level. In addition, effect estimates should help to decide on and to prepare a controlled trial. Methods/Design Standard basic and advanced Kinaesthetics courses (each comprising four subsequent days and an additional counselling day during the following four months are offered to n = 36 out of 60 nurses in a residential geriatric care home, who are in charge of 76 residents. N = 22 residents needing movement support are participating to this study. On the staff level, measurements include focus group discussions, questionnaires, physical strain self-assessment (Borg scale, video recordings and external observation of patient assistance skills using a specialised instrument (SOPMAS. Questionnaires used on the resident level include safety, comfort, pain, and level of own participation during mobilisation. A functional mobility profile is assessed using a specialised test procedure (MOTPA. Measurements will take place at baseline (T0, after basic training (T1, and after the advanced course (T2. Follow-up focus groups will be offered at T1 and 10 months later (T3. Discussion Ten criteria for feasibility success are established before the trial, assigned to resources (missing data, processes (drop-out of nurses and residents and science (minimum effects criteria. This will help to make rational decision on entering the next stage of the research

  5. Two-stage free electron laser research

    Science.gov (United States)

    Segall, S. B.

    1984-10-01

    KMS Fusion, Inc. began studying the feasibility of two-stage free electron lasers for the Office of Naval Research in June, 1980. At that time, the two-stage FEL was only a concept that had been proposed by Luis Elias. The range of parameters over which such a laser could be successfully operated, attainable power output, and constraints on laser operation were not known. The primary reason for supporting this research at that time was that it had the potential for producing short-wavelength radiation using a relatively low voltage electron beam. One advantage of a low-voltage two-stage FEL would be that shielding requirements would be greatly reduced compared with single-stage short-wavelength FEL's. If the electron energy were kept below about 10 MeV, X-rays, generated by electrons striking the beam line wall, would not excite neutron resonance in atomic nuclei. These resonances cause the emission of neutrons with subsequent induced radioactivity. Therefore, above about 10 MeV, a meter or more of concrete shielding is required for the system, whereas below 10 MeV, a few millimeters of lead would be adequate.

  6. Managing uncertainty - a qualitative study of surgeons' decision-making for one-stage and two-stage revision surgery for prosthetic hip joint infection.

    Science.gov (United States)

    Moore, Andrew J; Blom, Ashley W; Whitehouse, Michael R; Gooberman-Hill, Rachael

    2017-04-12

    Approximately 88,000 primary hip replacements are performed in England and Wales each year. Around 1% go on to develop deep prosthetic joint infection. Between one-stage and two-stage revision arthroplasty best treatment options remain unclear. Our aims were to characterise consultant orthopaedic surgeons' decisions about performing either one-stage or two-stage revision surgery for patients with deep prosthetic infection (PJI) after hip arthroplasty, and to identify whether a randomised trial comparing one-stage with two-stage revision would be feasible. Semi-structured interviews were conducted with 12 consultant surgeons who perform revision surgery for PJI after hip arthroplasty at 5 high-volume National Health Service (NHS) orthopaedic departments in England and Wales. Surgeons were interviewed before the development of a multicentre randomised controlled trial. Data were analysed using a thematic approach. There is no single standardised surgical intervention for the treatment of PJI. Surgeons balance multiple factors when choosing a surgical strategy which include multiple patient-related factors, their own knowledge and expertise, available infrastructure and the infecting organism. Surgeons questioned whether it was appropriate that the two-stage revision remained the best treatment, and some surgeons' willingness to consider more one-stage revisions had increased over recent years and were influenced by growing evidence showing equivalence between surgical techniques, and local observations of successful one-stage revisions. Custom-made articulating spacers was a practice that enabled uncertainty to be managed in the absence of definitive evidence about the superiority of one surgical technique over the other. Surgeons highlighted the need for research evidence to inform practice and thought that a randomised trial to compare treatments was needed. Most surgeons thought that patients who they treated would be eligible for trial participation in instances

  7. Two-stage turbo-compressor for heat pumps. Stage 1: Feasibility study; Compresseur radial pour pompe a chaleur bietagee. Phase 1: etude de faisabilite

    Energy Technology Data Exchange (ETDEWEB)

    Shiffmann, J; Molyneaux, A [Ofttech SA, Parc Scientifique de l' EPFL-C, Lausanne (Switzerland); Favrat, D; Marechal, F; Zehnder, M; Godat, J [Swiss Federal Institue of Technology (EPFL), Laboratoire d' energetique industrielle, Lausanne (Switzerland)

    2002-07-01

    This report describes the work performed by Ofttech SA, in collaboration with the Industrial Energy Laboratory (LENI) of the Swiss Federal Institute of Technology (EPFL) in Lausanne, investigating the feasibility of designing an oil-free turbo-compressor for domestic retrofit heat pump applications. The primary objective for a retrofit heat pump is that it produces heating water at 60 {sup o}C (with at least 10 {sup o}C temperature rise) with an external air temperature of -12 {sup o}C and can supply at least 10 kW. This would enable the air-water heat pump to directly replace oil or gas boilers. To enable a heat pump to produce the required hot water with a sufficient Coefficient of Performance (COP) a two-stage compressor is the most sensible technical solution currently available. This report shows how a turbo-compressor consisting of a single rotor with two centrifugal compressor wheels, running at variable speeds up to 240,000 rpm, can provide a unique solution with better predicted performance than existing solutions. This is possible by the use of bearings lubricated with gaseous refrigerant - excluding completely the need for oil in the system with its associated heat transfer, system, environmental and cost disadvantages. These bearings need radial clearances between 5 and 10 micrometers, leading to manufacturing tolerances in the order of magnitude of one micrometer. Various possible refrigerants are discussed with R134a being chosen for this study. Investigations performed by the company Asea Brown Boveri (ABB) are reported showing the possible design of the two small turbo-compressors resulting in wheels of less than 20 mm. The electric motor for this directly driven compressor together with the wheels and gas bearings will result in a complete rotor of less than 100 mm long - making it smaller, lighter and cheaper than existing compressors. The main conclusion is that the overall performance of this novel turbo-compressor when compared with the

  8. Does psychological functioning mediate the relationship between bullying involvement and weight loss preoccupation in adolescents? A two-stage cross-sectional study.

    Science.gov (United States)

    Lee, Kirsty; Guy, Alexa; Dale, Jeremy; Wolke, Dieter

    2017-03-24

    Adolescent bullying is associated with a range of adversities for those who are bullied i.e., victims and bully-victims (e.g., those who bully others and get victimised), including reduced psychological functioning and eating disorder symptoms. Bullies are generally well-adjusted psychologically, but previous research suggests that bullies may also engage in problematic diet behaviours. This study investigates a) whether adolescents involved in bullying (bullies, victims, bully-victims) are at increased risk of weight loss preoccupation, b) whether psychological functioning mediates this relationship and c) whether sex is a key moderator. A two-stage design was used. In stage 1, adolescents (n = 2782) from five UK secondary schools were screened for bullying involvement using self and peer reports. In stage 2, a sample of bullies, victims, bully-victims and uninvolved adolescents (n = 767) completed a battery of assessments. The measures included the eating behaviours component of the Child and Adolescent Psychiatric Assessment, which was reduced to one factor (weight loss preoccupation) and used as the outcome variable. Measures of self-esteem, body-esteem and emotional problems were reduced to a latent (mediator) variable of psychological functioning. Multi-group analysis examined the effects of sex and all models were adjusted for covariates (BMI, pubertal stage, age, parental education and ethnicity). Bullies, victims and bully-victims were at increased risk of weight loss preoccupation compared to adolescents uninvolved in bullying. The mechanism by which bullying involvement related to increased weight loss preoccupation varied by bullying role: in bullies the effect was direct, in victims the effect was indirect (via reduced psychological functioning) and in bully-victims the effect was both direct and indirect. Sex significantly moderated the relationship in bullies: weight loss preoccupation was only statistically significant in bullies who were

  9. Studies of two stage gas turbine combustor for biomass powder. Part 1, Atmospheric cyclone gasification experiments with wood powder. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Degerman, Bengt; Hedin, Johan; Fredriksson, Christian; Kjellstroem, Bjoern; Salman, Hassan [Luleaa Univ. of Technology (Sweden). Dept. of Mechanical Engineering

    2000-10-01

    This report summarises the research and development work regarding development of a two stage gas turbine combustor for wood powder carried out at the Luleaa University of Technology from July 1993 to December 1996. The process being studied is based on cyclone gasification of the wood powder and combustion of the product gas in a suitably adapted gas turbine combustion chamber, without other gas cleaning than that obtained by the cyclone. A critical issue to be studied in the project is if the burned gases from such a cyclone gasifier lead to acceptably low deposition rates for K- and Na-compounds in a gas turbine with 850 deg C inlet temperature. The project strategy has been to study wood powder feeding and cyclone gasification first at atmospheric pressure, then run separate pressurised cyclone gasification tests for studies of the possibilities to achieve stable operation when the air flow is supplied by a separate compressor and finally to run integrated gasifier/gas turbine tests for studies of the deposition problem in practical operation. During the period covered by this report the atmospheric test facility has been designed, built and commissioned. It has been used mainly for studies of injector feeding of wood powder into a cyclone gasifier and for gasification experiments where in particular the fate of ash elements introduced with the wood powder has been studied. The results of these experiments have shown that steam injection of wood powder is possible with a steam consumption of about 0.3 kg steam/kg wood. The effects of injector geometry on the performance has also been studied. The gasification experiments show clearly that ash elements, including K and Na remain in the ash until very late in the thermal conversion process, also at gas temperatures exceeding 900 deg C. The separation of K with the cyclone bottom char has been 50 - 60% and the separation of Na about 80% with the cyclone geometry and the wood powder tested. The resulting load of K

  10. Two-stage anaerobic digestion of cheese whey

    Energy Technology Data Exchange (ETDEWEB)

    Lo, K V; Liao, P H

    1986-01-01

    A two-stage digestion of cheese whey was studied using two anaerobic rotating biological contact reactors. The second-stage reactor receiving partially treated effluent from the first-stage reactor could be operated at a hydraulic retention time of one day. The results indicated that two-stage digestion is a feasible alternative for treating whey. 6 references.

  11. An open-label, two-stage, phase II study of bevacizumab and lapatinib in children with recurrent or refractory ependymoma: a collaborative ependymoma research network study (CERN).

    Science.gov (United States)

    DeWire, Mariko; Fouladi, Maryam; Turner, David C; Wetmore, Cynthia; Hawkins, Cynthia; Jacobs, Carmen; Yuan, Ying; Liu, Diane; Goldman, Stewart; Fisher, Paul; Rytting, Michael; Bouffet, Eric; Khakoo, Yasmin; Hwang, Eugene I; Foreman, Nicholas; Stewart, Clinton F; Gilbert, Mark R; Gilbertson, Richard; Gajjar, Amar

    2015-05-01

    Co-expression of ERBB2 and ERBB4, reported in 75% of pediatric ependymomas, correlates with worse overall survival. Lapatinib, a selective ERBB1 and ERBB2 inhibitor has produced prolonged disease stabilization in patients with ependymoma in a phase I study. Bevacizumab exposure in ependymoma xenografts leads to ablation of tumor self-renewing cells, arresting growth. Thus, we conducted an open-label, phase II study of bevacizumab and lapatinib in children with recurrent ependymomas. Patients ≤ 21 years of age with recurrent ependymoma received lapatinib orally twice daily (900 mg/m(2)/dose to the first 10 patients, and then 700 mg/m(2)/dose) and bevacizumab 10 mg/kg intravenously on days 1 and 15 of a 28-day course. Lapatinib serum trough levels were analyzed prior to each course. Total and phosphorylated VEGFR2 expression was measured in peripheral blood mononuclear cells (PBMCs) before doses 1 and 2 of bevacizumab and 24-48 h following dose 2 of bevacizumab. Twenty-four patients with a median age of 10 years (range 2-21 years) were enrolled; 22 were eligible and 20 evaluable for response. Thirteen had anaplastic ependymoma. There were no objective responses; 4 patients had stable disease for ≥ 4 courses (range 4-14). Grade 3 toxicities included rash, elevated ALT, and diarrhea. Grade 4 toxicities included peri-tracheostomy hemorrhage (n = 1) and elevated creatinine phosphokinase (n = 1). The median lapatinib pre-dose trough concentration was 3.72 µM. Although the combination of bevacizumab and lapatinib was well tolerated in children with recurrent ependymoma, it proved ineffective.

  12. Sensitivity Analysis in Two-Stage DEA

    Directory of Open Access Journals (Sweden)

    Athena Forghani

    2015-07-01

    Full Text Available Data envelopment analysis (DEA is a method for measuring the efficiency of peer decision making units (DMUs which uses a set of inputs to produce a set of outputs. In some cases, DMUs have a two-stage structure, in which the first stage utilizes inputs to produce outputs used as the inputs of the second stage to produce final outputs. One important issue in two-stage DEA is the sensitivity of the results of an analysis to perturbations in the data. The current paper looks into combined model for two-stage DEA and applies the sensitivity analysis to DMUs on the entire frontier. In fact, necessary and sufficient conditions for preserving a DMU's efficiency classiffication are developed when various data changes are applied to all DMUs.

  13. Sensitivity Analysis in Two-Stage DEA

    Directory of Open Access Journals (Sweden)

    Athena Forghani

    2015-12-01

    Full Text Available Data envelopment analysis (DEA is a method for measuring the efficiency of peer decision making units (DMUs which uses a set of inputs to produce a set of outputs. In some cases, DMUs have a two-stage structure, in which the first stage utilizes inputs to produce outputs used as the inputs of the second stage to produce final outputs. One important issue in two-stage DEA is the sensitivity of the results of an analysis to perturbations in the data. The current paper looks into combined model for two-stage DEA and applies the sensitivity analysis to DMUs on the entire frontier. In fact, necessary and sufficient conditions for preserving a DMU's efficiency classiffication are developed when various data changes are applied to all DMUs.

  14. Longitudinal study of fingerprint recognition.

    Science.gov (United States)

    Yoon, Soweon; Jain, Anil K

    2015-07-14

    Human identification by fingerprints is based on the fundamental premise that ridge patterns from distinct fingers are different (uniqueness) and a fingerprint pattern does not change over time (persistence). Although the uniqueness of fingerprints has been investigated by developing statistical models to estimate the probability of error in comparing two random samples of fingerprints, the persistence of fingerprints has remained a general belief based on only a few case studies. In this study, fingerprint match (similarity) scores are analyzed by multilevel statistical models with covariates such as time interval between two fingerprints in comparison, subject's age, and fingerprint image quality. Longitudinal fingerprint records of 15,597 subjects are sampled from an operational fingerprint database such that each individual has at least five 10-print records over a minimum time span of 5 y. In regard to the persistence of fingerprints, the longitudinal analysis on a single (right index) finger demonstrates that (i) genuine match scores tend to significantly decrease when time interval between two fingerprints in comparison increases, whereas the change in impostor match scores is negligible; and (ii) fingerprint recognition accuracy at operational settings, nevertheless, tends to be stable as the time interval increases up to 12 y, the maximum time span in the dataset. However, the uncertainty of temporal stability of fingerprint recognition accuracy becomes substantially large if either of the two fingerprints being compared is of poor quality. The conclusions drawn from 10-finger fusion analysis coincide with the conclusions from single-finger analysis.

  15. Two-stage precipitation of plutonium trifluoride

    International Nuclear Information System (INIS)

    Luerkens, D.W.

    1984-04-01

    Plutonium trifluoride was precipitated using a two-stage precipitation system. A series of precipitation experiments identified the significant process variables affecting precipitate characteristics. A mathematical precipitation model was developed which was based on the formation of plutonium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter that can be used to control particle characteristics

  16. Two-Stage Series-Resonant Inverter

    Science.gov (United States)

    Stuart, Thomas A.

    1994-01-01

    Two-stage inverter includes variable-frequency, voltage-regulating first stage and fixed-frequency second stage. Lightweight circuit provides regulated power and is invulnerable to output short circuits. Does not require large capacitor across ac bus, like parallel resonant designs. Particularly suitable for use in ac-power-distribution system of aircraft.

  17. Catalytic Two-Stage Liquefaction (CTSL{trademark}) process: Laboratory scale studies modelling and technical assessment. Final report, [October 1, 1988--June 30, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Comolli, A.G.; Johanson, E.S.; Lee, L.K.; Popper, G.A.; Smith, T.O.

    1993-06-01

    Reported herein are the details and results of Laboratory-Scale experiments using sub-bituminous and bituminous coal concluded at Hydrocarbon Research, Inc., under DOE Contract No. AC22-88PCB8818 during the period October 1, 1988 to June 30, 1993. The work described in this report is primarily concerned with tests on a Laboratory Scale primarily using microautoclaves. Experiments were conducted evaluating coal, solvents, start-up oils, catalysts, thermal treatments, C0{sub 2} addition and sulfur compound effects. Other microautoclave tests are included in the companion topical reports for this contract, DE-88818-TOP-01 & 02 on Sub-Bituminous and Bituminous Bench-Scale and PDU activities. In addition to the Laboratory Scale Studies, kinetic data and modelling results from Bench-Scale and Microautoclave tests are interpreted and presented along with some economic updates and sensitivity studies.

  18. Does psychological functioning mediate the relationship between bullying involvement and weight loss preoccupation in adolescents? A two-stage cross-sectional study

    OpenAIRE

    Lee, Kirsty; Guy, Alexa; Dale, Jeremy; Wolke, Dieter

    2017-01-01

    Background Adolescent bullying is associated with a range of adversities for those who are bullied i.e., victims and bully-victims (e.g., those who bully others and get victimised), including reduced psychological functioning and eating disorder symptoms. Bullies are generally well-adjusted psychologically, but previous research suggests that bullies may also engage in problematic diet behaviours. This study investigates a) whether adolescents involved in bullying (bullies, victims, bully-vic...

  19. A study of the HEB longitudinal dynamics

    International Nuclear Information System (INIS)

    Larson, D.J.

    1993-12-01

    A study of the High Energy Booster (HEB) longitudinal dynamics is presented. Full derivations of ramp dependent longitudinal variables are given. The formulas assume that the input magnetic field and beam longitudinal emittance are known as a function of time, and that either the rf voltage or the rf bucket area are known as a function of time. Once these three inputs are specified, the formulas can be used to calculate values for all other longitudinal dynamics variables. The formulas have been incorporated into a single computer code named ELVIRA: Evaluation of Longitudinal Variables in Relativistic Accelerators. The ELVIRA code is documented here in detail. The ELVIRA code is used under two initial longitudinal emittance assumptions to plot ramp functions for the longitudinal dynamics design of the HEB as of May 5, 1992

  20. Condensate from a two-stage gasifier

    DEFF Research Database (Denmark)

    Bentzen, Jens Dall; Henriksen, Ulrik Birk; Hindsgaul, Claus

    2000-01-01

    Condensate, produced when gas from downdraft biomass gasifier is cooled, contains organic compounds that inhibit nitrifiers. Treatment with activated carbon removes most of the organics and makes the condensate far less inhibitory. The condensate from an optimised two-stage gasifier is so clean...... that the organic compounds and the inhibition effect are very low even before treatment with activated carbon. The moderate inhibition effect relates to a high content of ammonia in the condensate. The nitrifiers become tolerant to the condensate after a few weeks of exposure. The level of organic compounds...... and the level of inhibition are so low that condensate from the optimised two-stage gasifier can be led to the public sewer....

  1. Long-Term Follow-Up Study of Young Adults Treated for Unilateral Complete Cleft Lip, Alveolus, and Palate by a Treatment Protocol Including Two-Stage Palatoplasty: Speech Outcomes

    Science.gov (United States)

    Bittermann, Dirk; Janssen, Laura; Bittermann, Gerhard Koendert Pieter; Boonacker, Chantal; Haverkamp, Sarah; de Wilde, Hester; Van Der Heul, Marise; Specken, Tom FJMC; Koole, Ron; Kon, Moshe; Breugem, Corstiaan Cornelis; Mink van der Molen, Aebele Barber

    2017-01-01

    Background No consensus exists on the optimal treatment protocol for orofacial clefts or the optimal timing of cleft palate closure. This study investigated factors influencing speech outcomes after two-stage palate repair in adults with a non-syndromal complete unilateral cleft lip and palate (UCLP). Methods This was a retrospective analysis of adult patients with a UCLP who underwent two-stage palate closure and were treated at our tertiary cleft centre. Patients ≥17 years of age were invited for a final speech assessment. Their medical history was obtained from their medical files, and speech outcomes were assessed by a speech pathologist during the follow-up consultation. Results Forty-eight patients were included in the analysis, with a mean age of 21 years (standard deviation, 3.4 years). Their mean age at the time of hard and soft palate closure was 3 years and 8.0 months, respectively. In 40% of the patients, a pharyngoplasty was performed. On a 5-point intelligibility scale, 84.4% received a score of 1 or 2; meaning that their speech was intelligible. We observed a significant correlation between intelligibility scores and the incidence of articulation errors (P<0.001). In total, 36% showed mild to moderate hypernasality during the speech assessment, and 11%–17% of the patients exhibited increased nasalance scores, assessed through nasometry. Conclusions The present study describes long-term speech outcomes after two-stage palatoplasty with hard palate closure at a mean age of 3 years old. We observed moderate long-term intelligibility scores, a relatively high incidence of persistent hypernasality, and a high pharyngoplasty incidence. PMID:28573094

  2. Long-Term Follow-Up Study of Young Adults Treated for Unilateral Complete Cleft Lip, Alveolus, and Palate by a Treatment Protocol Including Two-Stage Palatoplasty: Speech Outcomes

    Directory of Open Access Journals (Sweden)

    Isabelle Francisca Petronella Maria Kappen

    2017-05-01

    Full Text Available BackgroundNo consensus exists on the optimal treatment protocol for orofacial clefts or the optimal timing of cleft palate closure. This study investigated factors influencing speech outcomes after two-stage palate repair in adults with a non-syndromal complete unilateral cleft lip and palate (UCLP.MethodsThis was a retrospective analysis of adult patients with a UCLP who underwent two-stage palate closure and were treated at our tertiary cleft centre. Patients ≥17 years of age were invited for a final speech assessment. Their medical history was obtained from their medical files, and speech outcomes were assessed by a speech pathologist during the follow-up consultation.ResultsForty-eight patients were included in the analysis, with a mean age of 21 years (standard deviation, 3.4 years. Their mean age at the time of hard and soft palate closure was 3 years and 8.0 months, respectively. In 40% of the patients, a pharyngoplasty was performed. On a 5-point intelligibility scale, 84.4% received a score of 1 or 2; meaning that their speech was intelligible. We observed a significant correlation between intelligibility scores and the incidence of articulation errors (P<0.001. In total, 36% showed mild to moderate hypernasality during the speech assessment, and 11%–17% of the patients exhibited increased nasalance scores, assessed through nasometry.ConclusionsThe present study describes long-term speech outcomes after two-stage palatoplasty with hard palate closure at a mean age of 3 years old. We observed moderate long-term intelligibility scores, a relatively high incidence of persistent hypernasality, and a high pharyngoplasty incidence.

  3. Long-Term Follow-Up Study of Young Adults Treated for Unilateral Complete Cleft Lip, Alveolus, and Palate by a Treatment Protocol Including Two-Stage Palatoplasty: Speech Outcomes.

    Science.gov (United States)

    Kappen, Isabelle Francisca Petronella Maria; Bittermann, Dirk; Janssen, Laura; Bittermann, Gerhard Koendert Pieter; Boonacker, Chantal; Haverkamp, Sarah; de Wilde, Hester; Van Der Heul, Marise; Specken, Tom Fjmc; Koole, Ron; Kon, Moshe; Breugem, Corstiaan Cornelis; Mink van der Molen, Aebele Barber

    2017-05-01

    No consensus exists on the optimal treatment protocol for orofacial clefts or the optimal timing of cleft palate closure. This study investigated factors influencing speech outcomes after two-stage palate repair in adults with a non-syndromal complete unilateral cleft lip and palate (UCLP). This was a retrospective analysis of adult patients with a UCLP who underwent two-stage palate closure and were treated at our tertiary cleft centre. Patients ≥17 years of age were invited for a final speech assessment. Their medical history was obtained from their medical files, and speech outcomes were assessed by a speech pathologist during the follow-up consultation. Forty-eight patients were included in the analysis, with a mean age of 21 years (standard deviation, 3.4 years). Their mean age at the time of hard and soft palate closure was 3 years and 8.0 months, respectively. In 40% of the patients, a pharyngoplasty was performed. On a 5-point intelligibility scale, 84.4% received a score of 1 or 2; meaning that their speech was intelligible. We observed a significant correlation between intelligibility scores and the incidence of articulation errors (Pspeech assessment, and 11%-17% of the patients exhibited increased nasalance scores, assessed through nasometry. The present study describes long-term speech outcomes after two-stage palatoplasty with hard palate closure at a mean age of 3 years old. We observed moderate long-term intelligibility scores, a relatively high incidence of persistent hypernasality, and a high pharyngoplasty incidence.

  4. Two-stage nonrecursive filter/decimator

    International Nuclear Information System (INIS)

    Yoder, J.R.; Richard, B.D.

    1980-08-01

    A two-stage digital filter/decimator has been designed and implemented to reduce the sampling rate associated with the long-term computer storage of certain digital waveforms. This report describes the design selection and implementation process and serves as documentation for the system actually installed. A filter design with finite-impulse response (nonrecursive) was chosen for implementation via direct convolution. A newly-developed system-test statistic validates the system under different computer-operating environments

  5. Hypospadias repair: Byar's two stage operation revisited.

    Science.gov (United States)

    Arshad, A R

    2005-06-01

    Hypospadias is a congenital deformity characterised by an abnormally located urethral opening, that could occur anywhere proximal to its normal location on the ventral surface of glans penis to the perineum. Many operations had been described for the management of this deformity. One hundred and fifteen patients with hypospadias were treated at the Department of Plastic Surgery, Hospital Kuala Lumpur, Malaysia between September 1987 and December 2002, of which 100 had Byar's procedure performed on them. The age of the patients ranged from neonates to 26 years old. Sixty-seven patients had penoscrotal (58%), 20 had proximal penile (18%), 13 had distal penile (11%) and 15 had subcoronal hypospadias (13%). Operations performed were Byar's two-staged (100), Bracka's two-staged (11), flip-flap (2) and MAGPI operation (2). The most common complication encountered following hypospadias surgery was urethral fistula at a rate of 18%. There is a higher incidence of proximal hypospadias in the Malaysian community. Byar's procedure is a very versatile technique and can be used for all types of hypospadias. Fistula rate is 18% in this series.

  6. Two-Stage Fuzzy Portfolio Selection Problem with Transaction Costs

    Directory of Open Access Journals (Sweden)

    Yanju Chen

    2015-01-01

    Full Text Available This paper studies a two-period portfolio selection problem. The problem is formulated as a two-stage fuzzy portfolio selection model with transaction costs, in which the future returns of risky security are characterized by possibility distributions. The objective of the proposed model is to achieve the maximum utility in terms of the expected value and variance of the final wealth. Given the first-stage decision vector and a realization of fuzzy return, the optimal value expression of the second-stage programming problem is derived. As a result, the proposed two-stage model is equivalent to a single-stage model, and the analytical optimal solution of the two-stage model is obtained, which helps us to discuss the properties of the optimal solution. Finally, some numerical experiments are performed to demonstrate the new modeling idea and the effectiveness. The computational results provided by the proposed model show that the more risk-averse investor will invest more wealth in the risk-free security. They also show that the optimal invested amount in risky security increases as the risk-free return decreases and the optimal utility increases as the risk-free return increases, whereas the optimal utility increases as the transaction costs decrease. In most instances the utilities provided by the proposed two-stage model are larger than those provided by the single-stage model.

  7. Meta-analysis of Gaussian individual patient data: Two-stage or not two-stage?

    Science.gov (United States)

    Morris, Tim P; Fisher, David J; Kenward, Michael G; Carpenter, James R

    2018-04-30

    Quantitative evidence synthesis through meta-analysis is central to evidence-based medicine. For well-documented reasons, the meta-analysis of individual patient data is held in higher regard than aggregate data. With access to individual patient data, the analysis is not restricted to a "two-stage" approach (combining estimates and standard errors) but can estimate parameters of interest by fitting a single model to all of the data, a so-called "one-stage" analysis. There has been debate about the merits of one- and two-stage analysis. Arguments for one-stage analysis have typically noted that a wider range of models can be fitted and overall estimates may be more precise. The two-stage side has emphasised that the models that can be fitted in two stages are sufficient to answer the relevant questions, with less scope for mistakes because there are fewer modelling choices to be made in the two-stage approach. For Gaussian data, we consider the statistical arguments for flexibility and precision in small-sample settings. Regarding flexibility, several of the models that can be fitted only in one stage may not be of serious interest to most meta-analysis practitioners. Regarding precision, we consider fixed- and random-effects meta-analysis and see that, for a model making certain assumptions, the number of stages used to fit this model is irrelevant; the precision will be approximately equal. Meta-analysts should choose modelling assumptions carefully. Sometimes relevant models can only be fitted in one stage. Otherwise, meta-analysts are free to use whichever procedure is most convenient to fit the identified model. © 2018 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.

  8. Nonlinear longitudinal dynamics studies at the ALS

    International Nuclear Information System (INIS)

    Byrd, J.M.; Cheng, W.-H.; De Santis, S.; Li, D.; Stupakov, G.; Zimmermann, F.

    1999-01-01

    We present a summary of results for a variety of studies of nonlinear longitudinal dynamics in the Advanced Light Source, an electron storage ring. These include observation of decoherence at injection, decay of an injected beam, forced synchrotron oscillations and diffusion from one bunch to the next. All of the measurements were made using a dual-scan streak camera which allowed the real-time observation of the longitudinal distribution of the electron beam

  9. Two-Stage Fuzzy Portfolio Selection Problem with Transaction Costs

    OpenAIRE

    Chen, Yanju; Wang, Ye

    2015-01-01

    This paper studies a two-period portfolio selection problem. The problem is formulated as a two-stage fuzzy portfolio selection model with transaction costs, in which the future returns of risky security are characterized by possibility distributions. The objective of the proposed model is to achieve the maximum utility in terms of the expected value and variance of the final wealth. Given the first-stage decision vector and a realization of fuzzy return, the optimal value expression of the s...

  10. Novel rare missense variations and risk of autism spectrum disorder: whole-exome sequencing in two families with affected siblings and a two-stage follow-up study in a Japanese population.

    Directory of Open Access Journals (Sweden)

    Jun Egawa

    Full Text Available Rare inherited variations in multiplex families with autism spectrum disorder (ASD are suggested to play a major role in the genetic etiology of ASD. To further investigate the role of rare inherited variations, we performed whole-exome sequencing (WES in two families, each with three affected siblings. We also performed a two-stage follow-up case-control study in a Japanese population. WES of the six affected siblings identified six novel rare missense variations. Among these variations, CLN8 R24H was inherited in one family by three affected siblings from an affected father and thus co-segregated with ASD. In the first stage of the follow-up study, we genotyped the six novel rare missense variations identified by WES in 241 patients and 667 controls (the Niigata sample. Only CLN8 R24H had higher mutant allele frequencies in patients (1/482 compared with controls (1/1334. In the second stage, this variation was further genotyped, yet was not detected in a sample of 309 patients and 350 controls (the Nagoya sample. In the combined Niigata and Nagoya samples, there was no significant association (odds ratio = 1.8, 95% confidence interval = 0.1-29.6. These results suggest that CLN8 R24H plays a role in the genetic etiology of ASD, at least in a subset of ASD patients.

  11. On the robustness of two-stage estimators

    KAUST Repository

    Zhelonkin, Mikhail

    2012-04-01

    The aim of this note is to provide a general framework for the analysis of the robustness properties of a broad class of two-stage models. We derive the influence function, the change-of-variance function, and the asymptotic variance of a general two-stage M-estimator, and provide their interpretations. We illustrate our results in the case of the two-stage maximum likelihood estimator and the two-stage least squares estimator. © 2011.

  12. Statistical Power in Longitudinal Network Studies

    NARCIS (Netherlands)

    Stadtfeld, Christoph; Snijders, Tom A. B.; Steglich, Christian; van Duijn, Marijtje

    2018-01-01

    Longitudinal social network studies may easily suffer from a lack of statistical power. This is the case in particular for studies that simultaneously investigate change of network ties and change of nodal attributes. Such selection and influence studies have become increasingly popular due to the

  13. Are Sibling Relationships Protective? A Longitudinal Study

    Science.gov (United States)

    Gass, Krista; Jenkins, Jennifer; Dunn, Judy

    2007-01-01

    Background: Although the protective effects of familial and parental support have been studied extensively in the child psychopathology literature, few studies have explored the protective quality of positive sibling relationships. Methods: A two-wave longitudinal design was used to examine the protective effect of positive sibling relationships…

  14. Study of CSR longitudinal bunch compression cavity

    International Nuclear Information System (INIS)

    Yin Dayu; Li Peng; Liu Yong; Xie Qingchun

    2009-01-01

    The scheme of longitudinal bunch compression cavity for the Cooling Storage Ring (CSR)is an important issue. Plasma physics experiments require high density heavy ion beam and short pulsed bunch,which can be produced by non-adiabatic compression of bunch implemented by a fast compression with 90 degree rotation in the longitudinal phase space. The phase space rotation in fast compression is initiated by a fast jump of the RF-voltage amplitude. For this purpose, the CSR longitudinal bunch compression cavity, loaded with FINEMET-FT-1M is studied and simulated with MAFIA code. In this paper, the CSR longitudinal bunch compression cavity is simulated and the initial bunch length of 238 U 72+ with 250 MeV/u will be compressed from 200 ns to 50 ns.The construction and RF properties of the CSR longitudinal bunch compression cavity are simulated and calculated also with MAFIA code. The operation frequency of the cavity is 1.15 MHz with peak voltage of 80 kV, and the cavity can be used to compress heavy ions in the CSR. (authors)

  15. Randomised study on single stage laparo-endoscopic rendezvous (intra-operative ERCP) procedure versus two stage approach (Pre-operative ERCP followed by laparoscopic cholecystectomy) for the management of cholelithiasis with choledocholithiasis.

    Science.gov (United States)

    Sahoo, Manash Ranjan; Kumar, Anil T; Patnaik, Aashish

    2014-07-01

    The 'Rendezvous' technique consists of laparoscopic cholecystectomy (LC) standards with intra-operative cholangiography followed by endoscopic sphincterotomy. The sphincterotome is driven across the papilla through a guidewire inserted by the transcystic route. In this study, we intended to compare the two methods in a prospective randomised trial. From 2005 to 2012, we enrolled 83 patients with a diagnosis of cholecysto-choledocolithiasis. They were randomised into two groups. In 'group-A',41 patients were treated with two stages management, first by pre-operative endoscopic retrograde cholangiopancreatography (ERCP) and common bile duct (CBD) clearance and second by LC. In 'group-B', 42 patients were treated with LC and intra-operative cholangiography; and when diagnosis of choledocholithiasis was confirmed, patients had undergone one stage management of by Laparo-endoscopic Rendezvous technique. In arm-A and arm-B groups, complete CBD clearance was achieved in 29 and 38 patients, respectively. Failure of the treatment in arm-A was 29% and in arm-B was 9.5%. In arm-A, selective CBD cannulation was achieved in 33 cases (80.5%) and in arm-B in 39 cases (93%). In arm-Agroup, post-ERCP hyperamylasia was presented in nine patients (22%) and severe pancreatitis in five patients (12%) versus none of the patients (0%) in arm-B group, respectively. Mean post-operative hospital stay in arm-A and arm-B groups are 10.9 and 6.8 days, respectively. One stage laparo-endoscopic rendezvous approach increases selective cannulation of CBD, reduces post-ERCP pancreatitis, reduces days of hospital stay, increases patient's compliance and prevents unnecessary intervention to CBD.

  16. Randomised study on single stage laparo-endoscopic rendezvous (intra-operative ERCP procedure versus two stage approach (Pre-operative ERCP followed by laparoscopic cholecystectomy for the management of cholelithiasis with choledocholithiasis

    Directory of Open Access Journals (Sweden)

    Manash Ranjan Sahoo

    2014-01-01

    Full Text Available Introduction : The ′Rendezvous′ technique consists of laparoscopic cholecystectomy (LC standards with intra-operative cholangiography followed by endoscopic sphincterotomy. The sphincterotome is driven across the papilla through a guidewire inserted by the transcystic route. In this study, we intended to compare the two methods in a prospective randomised trial. Materials And Methods: From 2005 to 2012, we enrolled 83 patients with a diagnosis of cholecysto-choledocolithiasis. They were randomised into two groups. In ′group-A′,41 patients were treated with two stages management, first by pre-operative endoscopic retrograde cholangiopancreatography (ERCP and common bile duct (CBD clearance and second by LC. In ′group-B′, 42 patients were treated with LC and intra-operative cholangiography; and when diagnosis of choledocholithiasis was confirmed, patients had undergone one stage management of by Laparo-endoscopic Rendezvous technique. Results: In arm-A and arm-B groups, complete CBD clearance was achieved in 29 and 38 patients, respectively. Failure of the treatment in arm-A was 29% and in arm-B was 9.5%. In arm-A, selective CBD cannulation was achieved in 33 cases (80.5% and in arm-B in 39 cases (93%. In arm-Agroup, post-ERCP hyperamylasia was presented in nine patients (22% and severe pancreatitis in five patients (12% versus none of the patients (0% in arm-B group, respectively. Mean post-operative hospital stay in arm-A and arm-B groups are 10.9 and 6.8 days, respectively. Conclusion: One stage laparo-endoscopic rendezvous approach increases selective cannulation of CBD, reduces post-ERCP pancreatitis, reduces days of hospital stay, increases patient′s compliance and prevents unnecessary intervention to CBD.

  17. Optics of two-stage photovoltaic concentrators with dielectric second stages

    Science.gov (United States)

    Ning, Xiaohui; O'Gallagher, Joseph; Winston, Roland

    1987-04-01

    Two-stage photovoltaic concentrators with Fresnel lenses as primaries and dielectric totally internally reflecting nonimaging concentrators as secondaries are discussed. The general design principles of such two-stage systems are given. Their optical properties are studied and analyzed in detail using computer ray trace procedures. It is found that the two-stage concentrator offers not only a higher concentration or increased acceptance angle, but also a more uniform flux distribution on the photovoltaic cell than the point focusing Fresnel lens alone. Experimental measurements with a two-stage prototype module are presented and compared to the analytical predictions.

  18. Optics of two-stage photovoltaic concentrators with dielectric second stages.

    Science.gov (United States)

    Ning, X; O'Gallagher, J; Winston, R

    1987-04-01

    Two-stage photovoltaic concentrators with Fresnel lenses as primaries and dielectric totally internally reflecting nonimaging concentrators as secondaries are discussed. The general design principles of such two-stage systems are given. Their optical properties are studied and analyzed in detail using computer ray trace procedures. It is found that the two-stage concentrator offers not only a higher concentration or increased acceptance angle, but also a more uniform flux distribution on the photovoltaic cell than the point focusing Fresnel lens alone. Experimental measurements with a two-stage prototype module are presented and compared to the analytical predictions.

  19. Collaborative Knowledge-Building: A Longitudinal Study

    Science.gov (United States)

    Li, Qing

    2009-01-01

    The focus of this paper is on knowledge-building in a technology-supported learning environment in higher education through a longitudinal study of a graduate course from 2003 to 2007. The primary question is: how do learning conditions designed into a graduate course contribute to collaborative knowledge building? In particular, two major…

  20. The Czech longitudinal study of optimal development

    Czech Academy of Sciences Publication Activity Database

    Kebza, V.; Šolcová, Iva; Kodl, M.; Kernová, V.

    2012-01-01

    Roč. 47, Suppl. 1 (2012), s. 266-266 ISSN 0020-7594. [International Congress of Psychology /30./. 22.07.2012-27.07.2012, Cape Town] R&D Projects: GA ČR GAP407/10/2410 Institutional support: RVO:68081740 Keywords : optimal development * Prague longitudinal study Subject RIV: AN - Psychology

  1. Burnout development among dentists : a longitudinal study

    NARCIS (Netherlands)

    te Brake, H.; Smits, N.; Wicherts, J.M.; Gorter, R.C.; Hoogstraten, J.

    2008-01-01

    Knowledge on the development of burnout among dentists is important for purposes of prevention and intervention. Using a two-wave longitudinal design, this study examined the chronological sequence of the three dimensions of the Maslach Burnout Inventory: emotional exhaustion; depersonalization; and

  2. Evaluating damping elements for two-stage suspension vehicles

    Directory of Open Access Journals (Sweden)

    Ronald M. Martinod R.

    2012-01-01

    Full Text Available The technical state of the damping elements for a vehicle having two-stage suspension was evaluated by using numerical models based on the multi-body system theory; a set of virtual tests used the eigenproblem mathematical method. A test was developed based on experimental modal analysis (EMA applied to a physical system as the basis for validating the numerical models. The study focused on evaluating vehicle dynamics to determine the influence of the dampers’ technical state in each suspension state.

  3. Development and study of a 3.2-mm-diameter, 1.2-m-long two-stage plasma-arc-driven railgun for hypervelocity hydrogen pellet injection

    International Nuclear Information System (INIS)

    Zhang, D.; Kim, K.

    1988-12-01

    A detailed description of a prototype, fuseless, plasma-arc-driven, two-stage railgun system with a 1.2-m-long railgun barrel and a 3.2-mm-diameter circular bore is presented, along with the preliminary results indicating its capabilities and limitations. A hydrogen pellet generator, which has a straight-tube configuration and which is also operated as a gas gun, is employed as the first stage of the two-stage acceleration system. The design details of this preacceleration system and the results illustrating its performance are first presented. The second-stage accelerator which acts as a booster accelerator, is a fuseless plasma-arc-driven railgun, and constitutes the core of the entire two-stage acceleration scheme. Details of its design, ancillary systems, operation, and performance are described next in this report. The experimental data included herein represent only the preliminary data, and the system modifications that led to the improvements are described in the accompanying two other progress reports that precede this. 19 refs

  4. Impact of the Early Start Denver Model on the cognitive level of children with autism spectrum disorder: study protocol for a randomised controlled trial using a two-stage Zelen design.

    Science.gov (United States)

    Touzet, Sandrine; Occelli, Pauline; Schröder, Carmen; Manificat, Sabine; Gicquel, Ludovic; Stanciu, Razvana; Schaer, Marie; Oreve, Marie-Joelle; Speranza, Mario; Denis, Angelique; Zelmar, Amelie; Falissard, Bruno; Georgieff, Nicolas; Bahrami, Stephane; Geoffray, Marie-Maude

    2017-03-27

    Early intervention for autism spectrum disorder (ASD) in the European French-speaking countries is heterogeneous and poorly evaluated to date. Early intervention units applying the Early Start Denver Model (ESDM) for toddlers and young children with ASD have been created in France and Belgium to improve this situation. It is essential to evaluate this intervention for the political decision-making process regarding ASD interventions in European French-speaking countries. We will evaluate the effectiveness of 12 hours per week ESDM intervention on the cognitive level of children with ASD, over a 2-year period. The study will be a multicentre, randomised controlled trial, using a two-stage Zelen design. Children aged 15-36 months, diagnosed with ASD and with a developmental quotient (DQ) of 30 or above on the Mullen Scale of Early Learning (MSEL) will be included. We will use a stratified minimisation randomisation at a ratio 1:2 in favour of the control group. The sample size required is 180 children (120 in the control and 60 in the intervention group). The experimental group will receive 12 hours per week ESDM by trained therapists 10 hours per week in the centre and 2 hours in the toddlers' natural environment (alternatively by the therapist and the parent). The control group will receive care available in the community. The primary outcome will be the change in cognitive level measured with the DQ of the MSEL scored at 2 years. Secondary outcomes will include change in autism symptoms, behavioural adaptation, communicative and productive language level, sensory profile and parents' quality of life. The primary analysis will use the intention-to-treat principle. An economic evaluation will be performed. Findings from the study will be disseminated through peer reviewed publications and meetings. NCT02608333 (clinicaltrials.gov); Pre-results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence

  5. Delphi project in bronchial asthma. Two stages.

    Science.gov (United States)

    Fernández-Benítez, M; Ibero Iborra, M; Sanz Ortega, J; Garde Garde, J

    2010-01-01

    From the paediatric point of view, we have undertaken two Delphi studies into bronchial asthma. The first is related to the consensus known as the consensus document of the five associations. The second is more recent and has been undertaken with GEMA (the Spanish Guidelines on the Management of Asthma). The aim of this paper is to carry out a descriptive study comparing the 2 Delphi processes and to objectively assess if in some way behaviour over the past two years has changed as far as expert opinion is concerned. In the consensus document those points giving rise to most controversy were the treatment of children under three years of age and treatment with immunotherapy in allergic asthma. It is also necessary to highlight how important it was at that particular point in time to define the phenotypes of wheezing and the predictive index of asthma in children of less than 3 years of age. Of the 52 questions in the questionnaire, in 13.6% the panel of experts reached no consensus in their positions. Following GEMA the Delphi methodology, 56 questions were asked in the first round of the questionnaire, and consensus was reached in 87.5%. As regards the paediatric part relating to diagnosis and treatment in children, agreement was reached on all the questions in the first round. Agreement was reached in 8.92% questions in the second round. Clinical guidelines and consensus documents can modify behaviour towards an illness, both in the diagnosis and treatment. Copyright © 2010 SEICAP. Published by Elsevier Espana. All rights reserved.

  6. Short term load forecasting: two stage modelling

    Directory of Open Access Journals (Sweden)

    SOARES, L. J.

    2009-06-01

    Full Text Available This paper studies the hourly electricity load demand in the area covered by a utility situated in the Seattle, USA, called Puget Sound Power and Light Company. Our proposal is put into proof with the famous dataset from this company. We propose a stochastic model which employs ANN (Artificial Neural Networks to model short-run dynamics and the dependence among adjacent hours. The model proposed treats each hour's load separately as individual single series. This approach avoids modeling the intricate intra-day pattern (load profile displayed by the load, which varies throughout days of the week and seasons. The forecasting performance of the model is evaluated in similiar mode a TLSAR (Two-Level Seasonal Autoregressive model proposed by Soares (2003 using the years of 1995 and 1996 as the holdout sample. Moreover, we conclude that non linearity is present in some series of these data. The model results are analyzed. The experiment shows that our tool can be used to produce load forecasting in tropical climate places.

  7. Study on MnCl_2/CaCl_2–NH_3 two-stage solid sorption freezing cycle for refrigerated trucks at low engine load in summer

    International Nuclear Information System (INIS)

    Gao, P.; Zhang, X.F.; Wang, L.W.; Wang, R.Z.; Li, D.P.; Liang, Z.W.; Cai, A.F.

    2016-01-01

    Graphical abstract: A MnCl_2/CaCl_2–NH_3 two-stage solid sorption freezing cycle driven by the engine exhaust gas is proposed for refrigerated trucks. - Highlights: • A two-stage adsorption freezing system is designed and constructed for the refrigerated truck. • Composite adsorbents of MnCl_2 and CaCl_2 with the matrix of ENG-TSA are developed. • The average refrigerating capacity of 2.2 kW in the adsorption process is obtained. • The chilled air outlet temperature of the evaporator is controlled at about −5 °C. • The COP is 0.13 when the heating and refrigerating temperatures are 230 °C and −5 °C. - Abstract: A novel MnCl_2/CaCl_2–NH_3 two-stage solid sorption freezing cycle is designed and established for the refrigerated truck with the rated power of 80 kW. The conventional sorption/desorption process and the resorption process are combined in the two-stage cycle. Theoretical analysis shows that such a cycle could adapt to the low heat source temperature and the high cooling temperature of the sorption beds very well, which is quite essential for the truck when the running speed and the load are low in summer. The expanded natural graphite treated with sulfuric acid (ENG-TSA) is chosen as the matrix, and composite adsorbents of MnCl_2/ENG-TSA and CaCl_2/ENG-TSA are developed. The hot air heated by the electric heater is used to simulate the engine exhaust gas to drive the system. When the hot air, the ambient air and the refrigerating temperature are 230 °C, 30 °C and −5 °C, respectively, the average refrigerating capacity is 2.2 kW in the sorption process. Correspondingly, the COP and SCP are 0.13 and 91.7 W/kg, respectively. The average refrigerating capacity of 1.1 kW in one cycle is gotten, which could meet the required refrigerating capacity of the light refrigerated truck at the low engine load engine in summer.

  8. Experimental and kinetics studies of aromatic hydrogenation in a two-stage hydrotreating process using NiMo/Al{sub 2}O{sub 3} and NiW/Al{sub 2}O{sub 3} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Owusu-Boakye, A.; Dalai, A.K.; Ferdous, D. [Saskatchewan Univ., Saskatoon, SK (Canada). Dept. of Chemical Engineering, Catalysis and Chemical Reaction Engineering Laboratories; Adjaye, J. [Syncrude Canada Ltd., Edmonton, AB (Canada)

    2006-10-15

    The degree of hydrogenation of aromatics in light gas oil (LGO) feed from Athabasca bitumen was examined using a two-stage process. Experiments were conducted in a trickle-bed reactor using 2 catalysts, namely nickel molybdenum alumina (NiMo/Al{sub 2}O{sub 3}) in stage one and nickel tungsten alumina (NiW/Al{sub 2}O{sub 3}) in the second stage. NiMo/Al{sub 2}O{sub 3} was used in the first stage in order to remove nitrogen and sulphur containing heteroatoms. NiW/Al{sub 2}O{sub 3} was used in the second stage for saturation of the aromatic rings in the hydrocarbon species. The catalysts were used under a range of temperature and pressure condition. Temperature and liquid hourly space velocity ranged from 350 to 390 degrees C and 1.0 to 1.5 per hour, respectively. Pressure was kept constant at 11.0 MPa for all experiments. Reaction time results from the two-stage process were compared with those from a single-stage where hydrotreating was performed over NiMo/AL{sub 2}O{sub 3}. Product samples from different feedstocks were analyzed with respect to sulfur, nitrogen and aromatic content. Gasoline selectivity and kinetic parameters for hydrodesulphurization (HDS) or hydrodenitrogenation (HDN) reactions for the feed materials were also compared. The effect of hydrogen sulphide (H{sub 2}S) inhibition on aromatics hydrogenation (HDA) was also kinetically modelled using the Langmuir-Hinshelwood approach. Kinetic analysis of the single-stage hydrotreating process showed that HDA and HDS activities were slowed by the presence of hydrogen sulphide that is produced as a by-product of the HDS process. However, with inter-stage removal of hydrogen sulphide in the two-stage process, significant improvement of the HDA and HDS activities were noted. It was concluded that the experimental data was successfully predicted by the Langmuir-Hinshelwood kinetic models. 27 refs., 4 tabs., 8 figs.

  9. Hybrid biogas upgrading in a two-stage thermophilic reactor

    DEFF Research Database (Denmark)

    Corbellini, Viola; Kougias, Panagiotis; Treu, Laura

    2018-01-01

    The aim of this study is to propose a hybrid biogas upgrading configuration composed of two-stage thermophilic reactors. Hydrogen is directly injected in the first stage reactor. The output gas from the first reactor (in-situ biogas upgrade) is subsequently transferred to a second upflow reactor...... (ex-situ upgrade), in which enriched hydrogenotrophic culture is responsible for the hydrogenation of carbon dioxide to methane. The overall objective of the work was to perform an initial methane enrichment in the in-situ reactor, avoiding deterioration of the process due to elevated pH levels......, and subsequently, to complete the biogas upgrading process in the ex-situ chamber. The methane content in the first stage reactor reached on average 87% and the corresponding value in the second stage was 91%, with a maximum of 95%. A remarkable accumulation of volatile fatty acids was observed in the first...

  10. Residents’ perceptions of an integrated longitudinal curriculum: a qualitative study

    Directory of Open Access Journals (Sweden)

    Rebecca Lubitz

    2015-12-01

    Conclusions: This study suggests that an integrated longitudinalized family medicine block training model has the potential to support the principles of a longitudinal integrated competency-based curriculum to effectively prepare residents for family medicine practice.

  11. Longitudinal study on osteoarthritis and bone metabolism

    Directory of Open Access Journals (Sweden)

    L. Postiglione

    2011-09-01

    Full Text Available Objective: The relationship between Osteoarthritis (OA and Osteoporosis (OP is not well defined due to lacking in longitudinal data, mainly regarding correlations between biochemical factors and OA incidence. Aim of this paper was to investigate the predictive value for OA incidence of bone mass variations and of selected biochemical markers in healthy women participating in a population-based longitudinal study carried out in Naples (Italy. Subjects and Methods: High completion rate (85.2% and statistically adequate sample size were obtained: 139 women (45 to 79 years of age were examined and follow up visit was performed after two years (24±2 months, following the same protocol. Patients underwent medical examination, questionnaire, anthropometric measurements, blood sampling and urine collection. Bone mineral density (BMD measurement was performed by dual energy X-ray absorptiometry (DEXA at the lumbar spine (L1-L4 and femoral neck. Radiographs of dorsal and lumbar spine in lateral view were performed at basal and at 24 months visits; a team of three experts scored radiographs using Kellegren and Lawrence grading. Results: The score was calculated for two individual radiographic features (narrowing of the joint space, presence of osteophytes and as a global score. Results show a relevant percentage, 23% up, of subjects presenting both OA and OP. In the cross-sectional study the presence of osteophytosis correlates with anthropometric variables and PTH levels. In the longitudinal study results show a correlation between serum vitamin D and delta score for osteophytosis (β=0.02 p<0.05. Conclusions: Data obtained outline the importance of further studies on the pathogenetic link between OA and bone metabolism.

  12. Two-stage exchange knee arthroplasty: does resistance of the infecting organism influence the outcome?

    Science.gov (United States)

    Kurd, Mark F; Ghanem, Elie; Steinbrecher, Jill; Parvizi, Javad

    2010-08-01

    Periprosthetic joint infection after TKA is a challenging complication. Two-stage exchange arthroplasty is the accepted standard of care, but reported failure rates are increasing. It has been suggested this is due to the increased prevalence of methicillin-resistant infections. We asked the following questions: (1) What is the reinfection rate after two-stage exchange arthroplasty? (2) Which risk factors predict failure? (3) Which variables are associated with acquiring a resistant organism periprosthetic joint infection? This was a case-control study of 102 patients with infected TKA who underwent a two-stage exchange arthroplasty. Ninety-six patients were followed for a minimum of 2 years (mean, 34.5 months; range, 24-90.1 months). Cases were defined as failures of two-stage exchange arthroplasty. Two-stage exchange arthroplasty was successful in controlling the infection in 70 patients (73%). Patients who failed two-stage exchange arthroplasty were 3.37 times more likely to have been originally infected with a methicillin-resistant organism. Older age, higher body mass index, and history of thyroid disease were predisposing factors to infection with a methicillin-resistant organism. Innovative interventions are needed to improve the effectiveness of two-stage exchange arthroplasty for TKA infection with a methicillin-resistant organism as current treatment protocols may not be adequate for control of these virulent pathogens. Level IV, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

  13. A longitudinal study of urea cycle disorders.

    Science.gov (United States)

    Batshaw, Mark L; Tuchman, Mendel; Summar, Marshall; Seminara, Jennifer

    2014-01-01

    The Urea Cycle Disorders Consortium (UCDC) is a member of the NIH funded Rare Diseases Clinical Research Network and is performing a longitudinal study of 8 urea cycle disorders (UCDs) with initial enrollment beginning in 2006. The consortium consists of 14 sites in the U.S., Canada and Europe. This report summarizes data mining studies of 614 patients with UCDs enrolled in the UCDC's longitudinal study protocol. The most common disorder is ornithine transcarbamylase deficiency, accounting for more than half of the participants. We calculated the overall prevalence of urea cycle disorders to be 1/35,000, with 2/3rds presenting initial symptoms after the newborn period. We found the mortality rate to be 24% in neonatal onset cases and 11% in late onset cases. The most common precipitant of clinical hyperammonemic episodes in the post-neonatal period was intercurrent infections. Elevations in both blood ammonia and glutamine appeared to be biomarkers for neurocognitive outcome. In terms of chronic treatment, low protein diet appeared to result in normal weight but decreased linear growth while N-scavenger therapy with phenylbutyrate resulted in low levels of branched chain amino acids. Finally, we found an unexpectedly high risk for hepatic dysfunction in patients with ornithine transcarbamylase deficiency. This natural history study illustrates how a collaborative study of a rare genetic disorder can result in an improved understanding of morbidity and disease outcome. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Maximally efficient two-stage screening: Determining intellectual disability in Taiwanese military conscripts.

    Science.gov (United States)

    Chien, Chia-Chang; Huang, Shu-Fen; Lung, For-Wey

    2009-01-27

    The purpose of this study was to apply a two-stage screening method for the large-scale intelligence screening of military conscripts. We collected 99 conscripted soldiers whose educational levels were senior high school level or lower to be the participants. Every participant was required to take the Wisconsin Card Sorting Test (WCST) and the Wechsler Adult Intelligence Scale-Revised (WAIS-R) assessments. Logistic regression analysis showed the conceptual level responses (CLR) index of the WCST was the most significant index for determining intellectual disability (ID; FIQ ≤ 84). We used the receiver operating characteristic curve to determine the optimum cut-off point of CLR. The optimum one cut-off point of CLR was 66; the two cut-off points were 49 and 66. Comparing the two-stage window screening with the two-stage positive screening, the area under the curve and the positive predictive value increased. Moreover, the cost of the two-stage window screening decreased by 59%. The two-stage window screening is more accurate and economical than the two-stage positive screening. Our results provide an example for the use of two-stage screening and the possibility of the WCST to replace WAIS-R in large-scale screenings for ID in the future.

  15. A two-stage method for inverse medium scattering

    KAUST Repository

    Ito, Kazufumi; Jin, Bangti; Zou, Jun

    2013-01-01

    We present a novel numerical method to the time-harmonic inverse medium scattering problem of recovering the refractive index from noisy near-field scattered data. The approach consists of two stages, one pruning step of detecting the scatterer

  16. Evidence of two-stage melting of Wigner solids

    Science.gov (United States)

    Knighton, Talbot; Wu, Zhe; Huang, Jian; Serafin, Alessandro; Xia, J. S.; Pfeiffer, L. N.; West, K. W.

    2018-02-01

    Ultralow carrier concentrations of two-dimensional holes down to p =1 ×109cm-2 are realized. Remarkable insulating states are found below a critical density of pc=4 ×109cm-2 or rs≈40 . Sensitive dc V-I measurement as a function of temperature and electric field reveals a two-stage phase transition supporting the melting of a Wigner solid as a two-stage first-order transition.

  17. Parental mediation and cyberbullying - a longitudinal study.

    Science.gov (United States)

    Chng, Grace S; Liau, Albert; Khoo, Angeline; Li, Dongdong

    2014-01-01

    Parents use active and restrictive mediation strategies to guide and regulate children's online participation and the online risks they encounter. However, changes in parental mediation do occur over time and the effectiveness of these strategies on cyberbullying demands for further empirical investigation. The current study addresses these issues with a sample of 1084 students (49% girls) in a longitudinal, three-wave design. Gender differences were tested via multi-group analyses. Longitudinal growth models showed that parental use of both active and restrictive mediation decreased over time. For both types of mediation, the mean rate of change had a significant effect on boys' engagement in cyberbullying, but not for girls. Initial levels of restrictive mediation, but not active mediation, were found to be significantly predictive of cyberbullying in both genders. Girls had higher initial levels of both parental mediation types in comparison to boys. The results reveal that the effectiveness of active and restrictive mediation in relation to students' cyberbullying differs and informs us on gender differences. The implications of these results for parental education in online mediation are discussed.

  18. Eliminating Survivor Bias in Two-stage Instrumental Variable Estimators.

    Science.gov (United States)

    Vansteelandt, Stijn; Walter, Stefan; Tchetgen Tchetgen, Eric

    2018-07-01

    Mendelian randomization studies commonly focus on elderly populations. This makes the instrumental variables analysis of such studies sensitive to survivor bias, a type of selection bias. A particular concern is that the instrumental variable conditions, even when valid for the source population, may be violated for the selective population of individuals who survive the onset of the study. This is potentially very damaging because Mendelian randomization studies are known to be sensitive to bias due to even minor violations of the instrumental variable conditions. Interestingly, the instrumental variable conditions continue to hold within certain risk sets of individuals who are still alive at a given age when the instrument and unmeasured confounders exert additive effects on the exposure, and moreover, the exposure and unmeasured confounders exert additive effects on the hazard of death. In this article, we will exploit this property to derive a two-stage instrumental variable estimator for the effect of exposure on mortality, which is insulated against the above described selection bias under these additivity assumptions.

  19. Effect of Silica Fume on two-stage Concrete Strength

    Science.gov (United States)

    Abdelgader, H. S.; El-Baden, A. S.

    2015-11-01

    Two-stage concrete (TSC) is an innovative concrete that does not require vibration for placing and compaction. TSC is a simple concept; it is made using the same basic constituents as traditional concrete: cement, coarse aggregate, sand and water as well as mineral and chemical admixtures. As its name suggests, it is produced through a two-stage process. Firstly washed coarse aggregate is placed into the formwork in-situ. Later a specifically designed self compacting grout is introduced into the form from the lowest point under gravity pressure to fill the voids, cementing the aggregate into a monolith. The hardened concrete is dense, homogeneous and has in general improved engineering properties and durability. This paper presents the results from a research work attempt to study the effect of silica fume (SF) and superplasticizers admixtures (SP) on compressive and tensile strength of TSC using various combinations of water to cement ratio (w/c) and cement to sand ratio (c/s). Thirty six concrete mixes with different grout constituents were tested. From each mix twenty four standard cylinder samples of size (150mm×300mm) of concrete containing crushed aggregate were produced. The tested samples were made from combinations of w/c equal to: 0.45, 0.55 and 0.85, and three c/s of values: 0.5, 1 and 1.5. Silica fume was added at a dosage of 6% of weight of cement, while superplasticizer was added at a dosage of 2% of cement weight. Results indicated that both tensile and compressive strength of TSC can be statistically derived as a function of w/c and c/s with good correlation coefficients. The basic principle of traditional concrete, which says that an increase in water/cement ratio will lead to a reduction in compressive strength, was shown to hold true for TSC specimens tested. Using a combination of both silica fume and superplasticisers caused a significant increase in strength relative to control mixes.

  20. Comparative effectiveness of one-stage versus two-stage basilic vein transposition arteriovenous fistulas.

    Science.gov (United States)

    Ghaffarian, Amir A; Griffin, Claire L; Kraiss, Larry W; Sarfati, Mark R; Brooke, Benjamin S

    2018-02-01

    Basilic vein transposition (BVT) fistulas may be performed as either a one-stage or two-stage operation, although there is debate as to which technique is superior. This study was designed to evaluate the comparative clinical efficacy and cost-effectiveness of one-stage vs two-stage BVT. We identified all patients at a single large academic hospital who had undergone creation of either a one-stage or two-stage BVT between January 2007 and January 2015. Data evaluated included patient demographics, comorbidities, medication use, reasons for abandonment, and interventions performed to maintain patency. Costs were derived from the literature, and effectiveness was expressed in quality-adjusted life-years (QALYs). We analyzed primary and secondary functional patency outcomes as well as survival during follow-up between one-stage and two-stage BVT procedures using multivariate Cox proportional hazards models and Kaplan-Meier analysis with log-rank tests. The incremental cost-effectiveness ratio was used to determine cost savings. We identified 131 patients in whom 57 (44%) one-stage BVT and 74 (56%) two-stage BVT fistulas were created among 8 different vascular surgeons during the study period that each performed both procedures. There was no significant difference in the mean age, male gender, white race, diabetes, coronary disease, or medication profile among patients undergoing one- vs two-stage BVT. After fistula transposition, the median follow-up time was 8.3 months (interquartile range, 3-21 months). Primary patency rates of one-stage BVT were 56% at 12-month follow-up, whereas primary patency rates of two-stage BVT were 72% at 12-month follow-up. Patients undergoing two-stage BVT also had significantly higher rates of secondary functional patency at 12 months (57% for one-stage BVT vs 80% for two-stage BVT) and 24 months (44% for one-stage BVT vs 73% for two-stage BVT) of follow-up (P < .001 using log-rank test). However, there was no significant difference

  1. A Longitudinal Study of Prisoners on Remand

    DEFF Research Database (Denmark)

    Andersen, Henrik Steen; Sestoft, Dorte; Lillebæk, Tommy

    2000-01-01

    Objective: To compare two levels of stress (solitary confinement (SC) and non-SC) among remand prisoners as to incidence of psychiatric disorders in relation to prevalent disorders. Method: Longitudinal repeated assessments were carried out from the start and during the remand phase of imprisonment....... Both interview-based and self-reported measures were applied to 133 remand prisoners in SC and 95 remand prisoners in non-SC randomly selected in a parallel study design. Results: Incidence of psychiatric disorders developed in the prison was significantly higher in SC prisoners (28%) than in non......-SC prisoners (15%). Most disorders were adjustment disorders, with depressive disorders coming next. Incident psychotic disorders were rare. The difference regarding incidence was primarily explained by level of stress (i.e. prison form) rather than confounding factors. Quantitative measures of psychopathology...

  2. Maximally efficient two-stage screening: Determining intellectual disability in Taiwanese military conscripts

    Directory of Open Access Journals (Sweden)

    Chia-Chang Chien

    2009-01-01

    Full Text Available Chia-Chang Chien1, Shu-Fen Huang1,2,3,4, For-Wey Lung1,2,3,41Department of Psychiatry, Kaohsiung Armed Forces General Hospital, Kaohsiung, Taiwan; 2Graduate Institute of Behavioral Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan; 3Department of Psychiatry, National Defense Medical Center, Taipei, Taiwan; 4Calo Psychiatric Center, Pingtung County, TaiwanObjective: The purpose of this study was to apply a two-stage screening method for the large-scale intelligence screening of military conscripts.Methods: We collected 99 conscripted soldiers whose educational levels were senior high school level or lower to be the participants. Every participant was required to take the Wisconsin Card Sorting Test (WCST and the Wechsler Adult Intelligence Scale-Revised (WAIS-R assessments.Results: Logistic regression analysis showed the conceptual level responses (CLR index of the WCST was the most significant index for determining intellectual disability (ID; FIQ ≤ 84. We used the receiver operating characteristic curve to determine the optimum cut-off point of CLR. The optimum one cut-off point of CLR was 66; the two cut-off points were 49 and 66. Comparing the two-stage window screening with the two-stage positive screening, the area under the curve and the positive predictive value increased. Moreover, the cost of the two-stage window screening decreased by 59%.Conclusion: The two-stage window screening is more accurate and economical than the two-stage positive screening. Our results provide an example for the use of two-stage screening and the possibility of the WCST to replace WAIS-R in large-scale screenings for ID in the future.Keywords: intellectual disability, intelligence screening, two-stage positive screening, Wisconsin Card Sorting Test, Wechsler Adult Intelligence Scale-Revised

  3. Two-stage electrolysis to enrich tritium in environmental water

    International Nuclear Information System (INIS)

    Shima, Nagayoshi; Muranaka, Takeshi

    2007-01-01

    We present a two-stage electrolyzing procedure to enrich tritium in environmental waters. Tritium is first enriched rapidly through a commercially-available electrolyser with a large 50A current, and then through a newly-designed electrolyser that avoids the memory effect, with a 6A current. Tritium recovery factor obtained by such a two-stage electrolysis was greater than that obtained when using the commercially-available device solely. Water samples collected in 2006 in lakes and along the Pacific coast of Aomori prefecture, Japan, were electrolyzed using the two-stage method. Tritium concentrations in these samples ranged from 0.2 to 0.9 Bq/L and were half or less, that in samples collected at the same sites in 1992. (author)

  4. Two-stage image denoising considering interscale and intrascale dependencies

    Science.gov (United States)

    Shahdoosti, Hamid Reza

    2017-11-01

    A solution to the problem of reducing the noise of grayscale images is presented. To consider the intrascale and interscale dependencies, this study makes use of a model. It is shown that the dependency between a wavelet coefficient and its predecessors can be modeled by the first-order Markov chain, which means that the parent conveys all of the information necessary for efficient estimation. Using this fact, the proposed method employs the Kalman filter in the wavelet domain for image denoising. The proposed method has two stages. The first stage employs a simple denoising algorithm to provide the noise-free image, by which the parameters of the model such as state transition matrix, variance of the process noise, the observation model, and the covariance of the observation noise are estimated. In the second stage, the Kalman filter is applied to the wavelet coefficients of the noisy image to estimate the noise-free coefficients. In fact, the Kalman filter is used to estimate the coefficients of high-frequency subbands from the coefficients of coarser scales and noisy observations of neighboring coefficients. In this way, both the interscale and intrascale dependencies are taken into account. Results are presented and discussed on a set of standard 8-bit grayscale images. The experimental results demonstrate that the proposed method achieves performances competitive with the state-of-the-art denoising methods in terms of both peak-signal-to-noise ratio and subjective visual quality.

  5. Two-stage thermal/nonthermal waste treatment process

    International Nuclear Information System (INIS)

    Rosocha, L.A.; Anderson, G.K.; Coogan, J.J.; Kang, M.; Tennant, R.A.; Wantuck, P.J.

    1993-01-01

    An innovative waste treatment technology is being developed in Los Alamos to address the destruction of hazardous organic wastes. The technology described in this report uses two stages: a packed bed reactor (PBR) in the first stage to volatilize and/or combust liquid organics and a silent discharge plasma (SDP) reactor to remove entrained hazardous compounds in the off-gas to even lower levels. We have constructed pre-pilot-scale PBR-SDP apparatus and tested the two stages separately and in combined modes. These tests are described in the report

  6. Development of Explosive Ripper with Two-Stage Combustion

    Science.gov (United States)

    1974-10-01

    inch pipe duct work, the width of this duct proved to be detrimental in marginally rippable material; the duct, instead of the penetrator tip, was...marginally rippable rock. ID. Operating Requirements 2. Fuel The two-stage combustion device is designed to operate using S A 42. the same diesel

  7. Engineering analysis of the two-stage trifluoride precipitation process

    International Nuclear Information System (INIS)

    Luerkens, D.w.W.

    1984-06-01

    An engineering analysis of two-stage trifluoride precipitation processes is developed. Precipitation kinetics are modeled using consecutive reactions to represent fluoride complexation. Material balances across the precipitators are used to model the time dependent concentration profiles of the main chemical species. The results of the engineering analysis are correlated with previous experimental work on plutonium trifluoride and cerium trifluoride

  8. On the robustness of two-stage estimators

    KAUST Repository

    Zhelonkin, Mikhail; Genton, Marc G.; Ronchetti, Elvezio

    2012-01-01

    The aim of this note is to provide a general framework for the analysis of the robustness properties of a broad class of two-stage models. We derive the influence function, the change-of-variance function, and the asymptotic variance of a general

  9. Longitudinal morphometric MRI study of Alzheimer's disease

    International Nuclear Information System (INIS)

    Ogomori, Koji; Takano, Koichi; Kuwabara, Yasuo; Nakano, Seigo; Nawata, Hideyuki; Yano, Rika; Nishimura, Ryoji; Takita, Masashi

    2009-01-01

    A longitudinal morphometric MRI study of Alzheimer's disease (AD) was conducted to determine the relationship between the progression of the symptoms and the progression of the brain atrophy. The Voxel-based Specific Regional Analysis System for Alzheimer's Disease (VSRAD), developed by Matsuda et al. was used as a method of morphometry to perform the statistical MR image analysis. Thirty-eight patients of AD patients were investigated with VSRAD. These patients were divided into two groups according to the progression of symptoms based on a clinical evaluation. One group was the progress group (20 patients), while the other group was the stable group (18 patients) for comparison. The relationship was investigated between the speed of the symptomatic progression and the change in each VSRAD indicator. Consequently, the entorhinal Z-score and the entorhinal atrophy rate showed a correlation with the speed of the symptomatic progression. The increase of the entorhinal Z-score in the follow-up was larger in the progress group than that in the stable group (0.65/1.28 years in the progress group and 0.05/1.26 years in the stable group.). These results suggest that a rapid symptomatic progression in an AD patient accompanies the rapid progression of atrophy in the entorhinal cortex. (author)

  10. Single-stage Acetabular Revision During Two-stage THA Revision for Infection is Effective in Selected Patients.

    Science.gov (United States)

    Fink, Bernd; Schlumberger, Michael; Oremek, Damian

    2017-08-01

    patients were assessed before surgery, between stages, every 3 months during the first year after surgery, every 6 months during the second year postoperative, and at latest followup, and were retrospectively drawn from a longitudinally maintained institutional database. Thirty-four of 35 patients (97.2%; 95% CI, 85.4%-99.5%) appeared free of infection by criteria of Masri et al. and Zimmerli et al. at latest followup. The Harris hip score was 61 ± 13 points after the first operation and 82 ± 16 points 2 years after the second operation. This technique is a promising treatment option for periprosthetic infections of the hip in which substantial acetabular defects exclude implantation of a normal spacer and a two-stage revision of the femoral component is favored. Level IV, therapeutic study.

  11. A Longitudinal Study of Adolescent Adjustment Following Family Transitions

    Science.gov (United States)

    Ruschena, Eda; Prior, Margot; Sanson, Ann; Smart, Diana

    2005-01-01

    Background: This study examined the impact of family transitions, that is, parental separation, divorce, remarriage and death, upon the lives of Australian children and adolescents in a longitudinal study of temperament and development. Methods: Using longitudinal and concurrent questionnaire data, outcomes for young people experiencing…

  12. Accuracy of the One-Stage and Two-Stage Impression Techniques: A Comparative Analysis.

    Science.gov (United States)

    Jamshidy, Ladan; Mozaffari, Hamid Reza; Faraji, Payam; Sharifi, Roohollah

    2016-01-01

    Introduction . One of the main steps of impression is the selection and preparation of an appropriate tray. Hence, the present study aimed to analyze and compare the accuracy of one- and two-stage impression techniques. Materials and Methods . A resin laboratory-made model, as the first molar, was prepared by standard method for full crowns with processed preparation finish line of 1 mm depth and convergence angle of 3-4°. Impression was made 20 times with one-stage technique and 20 times with two-stage technique using an appropriate tray. To measure the marginal gap, the distance between the restoration margin and preparation finish line of plaster dies was vertically determined in mid mesial, distal, buccal, and lingual (MDBL) regions by a stereomicroscope using a standard method. Results . The results of independent test showed that the mean value of the marginal gap obtained by one-stage impression technique was higher than that of two-stage impression technique. Further, there was no significant difference between one- and two-stage impression techniques in mid buccal region, but a significant difference was reported between the two impression techniques in MDL regions and in general. Conclusion . The findings of the present study indicated higher accuracy for two-stage impression technique than for the one-stage impression technique.

  13. Accuracy of the One-Stage and Two-Stage Impression Techniques: A Comparative Analysis

    Directory of Open Access Journals (Sweden)

    Ladan Jamshidy

    2016-01-01

    Full Text Available Introduction. One of the main steps of impression is the selection and preparation of an appropriate tray. Hence, the present study aimed to analyze and compare the accuracy of one- and two-stage impression techniques. Materials and Methods. A resin laboratory-made model, as the first molar, was prepared by standard method for full crowns with processed preparation finish line of 1 mm depth and convergence angle of 3-4°. Impression was made 20 times with one-stage technique and 20 times with two-stage technique using an appropriate tray. To measure the marginal gap, the distance between the restoration margin and preparation finish line of plaster dies was vertically determined in mid mesial, distal, buccal, and lingual (MDBL regions by a stereomicroscope using a standard method. Results. The results of independent test showed that the mean value of the marginal gap obtained by one-stage impression technique was higher than that of two-stage impression technique. Further, there was no significant difference between one- and two-stage impression techniques in mid buccal region, but a significant difference was reported between the two impression techniques in MDL regions and in general. Conclusion. The findings of the present study indicated higher accuracy for two-stage impression technique than for the one-stage impression technique.

  14. Two-Stage Variable Sample-Rate Conversion System

    Science.gov (United States)

    Tkacenko, Andre

    2009-01-01

    A two-stage variable sample-rate conversion (SRC) system has been pro posed as part of a digital signal-processing system in a digital com munication radio receiver that utilizes a variety of data rates. The proposed system would be used as an interface between (1) an analog- todigital converter used in the front end of the receiver to sample an intermediatefrequency signal at a fixed input rate and (2) digita lly implemented tracking loops in subsequent stages that operate at v arious sample rates that are generally lower than the input sample r ate. This Two-Stage System would be capable of converting from an input sample rate to a desired lower output sample rate that could be var iable and not necessarily a rational fraction of the input rate.

  15. Energy demand in Portuguese manufacturing: a two-stage model

    International Nuclear Information System (INIS)

    Borges, A.M.; Pereira, A.M.

    1992-01-01

    We use a two-stage model of factor demand to estimate the parameters determining energy demand in Portuguese manufacturing. In the first stage, a capital-labor-energy-materials framework is used to analyze the substitutability between energy as a whole and other factors of production. In the second stage, total energy demand is decomposed into oil, coal and electricity demands. The two stages are fully integrated since the energy composite used in the first stage and its price are obtained from the second stage energy sub-model. The estimates obtained indicate that energy demand in manufacturing responds significantly to price changes. In addition, estimation results suggest that there are important substitution possibilities among energy forms and between energy and other factors of production. The role of price changes in energy-demand forecasting, as well as in energy policy in general, is clearly established. (author)

  16. Two-step two-stage fission gas release model

    International Nuclear Information System (INIS)

    Kim, Yong-soo; Lee, Chan-bock

    2006-01-01

    Based on the recent theoretical model, two-step two-stage model is developed which incorporates two stage diffusion processes, grain lattice and grain boundary diffusion, coupled with the two step burn-up factor in the low and high burn-up regime. FRAPCON-3 code and its in-pile data sets have been used for the benchmarking and validation of this model. Results reveals that its prediction is in better agreement with the experimental measurements than that by any model contained in the FRAPCON-3 code such as ANS 5.4, modified ANS5.4, and Forsberg-Massih model over whole burn-up range up to 70,000 MWd/MTU. (author)

  17. Two-stage precipitation of neptunium (IV) oxalate

    International Nuclear Information System (INIS)

    Luerkens, D.W.

    1983-07-01

    Neptunium (IV) oxalate was precipitated using a two-stage precipitation system. A series of precipitation experiments was used to identify the significant process variables affecting precipitate characteristics. Process variables tested were input concentrations, solubility conditions in the first stage precipitator, precipitation temperatures, and residence time in the first stage precipitator. A procedure has been demonstrated that produces neptunium (IV) oxalate particles that filter well and readily calcine to the oxide

  18. Frequency analysis of a two-stage planetary gearbox using two different methodologies

    Science.gov (United States)

    Feki, Nabih; Karray, Maha; Khabou, Mohamed Tawfik; Chaari, Fakher; Haddar, Mohamed

    2017-12-01

    This paper is focused on the characterization of the frequency content of vibration signals issued from a two-stage planetary gearbox. To achieve this goal, two different methodologies are adopted: the lumped-parameter modeling approach and the phenomenological modeling approach. The two methodologies aim to describe the complex vibrations generated by a two-stage planetary gearbox. The phenomenological model describes directly the vibrations as measured by a sensor fixed outside the fixed ring gear with respect to an inertial reference frame, while results from a lumped-parameter model are referenced with respect to a rotating frame and then transferred into an inertial reference frame. Two different case studies of the two-stage planetary gear are adopted to describe the vibration and the corresponding spectra using both models. Each case presents a specific geometry and a specific spectral structure.

  19. Optimisation of Refrigeration System with Two-Stage and Intercooler Using Fuzzy Logic and Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Bayram Kılıç

    2017-04-01

    Full Text Available Two-stage compression operation prevents excessive compressor outlet pressure and temperature and this operation provides more efficient working condition in low-temperature refrigeration applications. Vapor compression refrigeration system with two-stage and intercooler is very good solution for low-temperature refrigeration applications. In this study, refrigeration system with two-stage and intercooler were optimized using fuzzy logic and genetic algorithm. The necessary thermodynamic characteristics for optimization were estimated with Fuzzy Logic and liquid phase enthalpy, vapour phase enthalpy, liquid phase entropy, vapour phase entropy values were compared with actual values. As a result, optimum working condition of system was estimated by the Genetic Algorithm as -6.0449 oC for evaporator temperature, 25.0115 oC for condenser temperature and 5.9666 for COP. Morever, irreversibility values of the refrigeration system are calculated.

  20. Distribution of extracellular potassium and electrophysiologic changes during two-stage coronary ligation in the isolated, perfused canine heart

    NARCIS (Netherlands)

    Coronel, R.; Fiolet, J. W.; Wilms-Schopman, J. G.; Opthof, T.; Schaapherder, A. F.; Janse, M. J.

    1989-01-01

    We studied the relation between [K+]o and the electrophysiologic changes during a "Harris two-stage ligation," which is an occlusion of a coronary artery, preceded by a 30-minute period of 50% reduction of flow through the artery. This two-stage ligation has been reported to be antiarrhythmic. Local

  1. Performance of an iterative two-stage bayesian technique for population pharmacokinetic analysis of rich data sets

    NARCIS (Netherlands)

    Proost, Johannes H.; Eleveld, Douglas J.

    2006-01-01

    Purpose. To test the suitability of an Iterative Two-Stage Bayesian (ITSB) technique for population pharmacokinetic analysis of rich data sets, and to compare ITSB with Standard Two-Stage (STS) analysis and nonlinear Mixed Effect Modeling (MEM). Materials and Methods. Data from a clinical study with

  2. What stage are low-income and middle-income countries (LMICs) at with patient safety curriculum implementation and what are the barriers to implementation? A two-stage cross-sectional study

    Science.gov (United States)

    Ginsburg, Liane R; Dhingra-Kumar, Neelam; Donaldson, Liam J

    2017-01-01

    Objectives The improvement of safety in healthcare worldwide depends in part on the knowledge, skills and attitudes of staff providing care. Greater patient safety content in health professional education and training programmes has been advocated internationally. While WHO Patient Safety Curriculum Guides (for Medical Schools and Multi-Professional Curricula) have been widely disseminated in low-income and middle-income countries (LMICs) over the last several years, little is known about patient safety curriculum implementation beyond high-income countries. The present study examines patient safety curriculum implementation in LMICs. Methods Two cross-sectional surveys were carried out. First, 88 technical officers in Ministries of Health and WHO country offices were surveyed to identify the pattern of patient safety curricula at country level. A second survey followed that gathered information from 71 people in a position to provide institution-level perspectives on patient safety curriculum implementation. Results The majority, 69% (30/44), of the countries were either considering whether to implement a patient safety curriculum or actively planning, rather than actually implementing, or embedding one. Most organisations recognised the need for patient safety education and training and felt a safety curriculum was compatible with the values of their organisation; however, important faculty-level barriers to patient safety curriculum implementation were identified. Key structural markers, such as dedicated financial resources and relevant assessment tools to evaluate trainees’ patient safety knowledge and skills, were in place in fewer than half of organisations studied. Conclusions Greater attention to patient safety curriculum implementation is needed. The barriers to patient safety curriculum implementation we identified in LMICs are not unique to these regions. We propose a framework to act as a global standard for patient safety curriculum implementation

  3. What stage are low-income and middle-income countries (LMICs) at with patient safety curriculum implementation and what are the barriers to implementation? A two-stage cross-sectional study.

    Science.gov (United States)

    Ginsburg, Liane R; Dhingra-Kumar, Neelam; Donaldson, Liam J

    2017-06-15

    The improvement of safety in healthcare worldwide depends in part on the knowledge, skills and attitudes of staff providing care. Greater patient safety content in health professional education and training programmes has been advocated internationally. While WHO Patient Safety Curriculum Guides (for Medical Schools and Multi-Professional Curricula) have been widely disseminated in low-income and middle-income countries (LMICs) over the last several years, little is known about patient safety curriculum implementation beyond high-income countries. The present study examines patient safety curriculum implementation in LMICs. Two cross-sectional surveys were carried out. First, 88 technical officers in Ministries of Health and WHO country offices were surveyed to identify the pattern of patient safety curricula at country level. A second survey followed that gathered information from 71 people in a position to provide institution-level perspectives on patient safety curriculum implementation. The majority, 69% (30/44), of the countries were either considering whether to implement a patient safety curriculum or actively planning, rather than actually implementing, or embedding one. Most organisations recognised the need for patient safety education and training and felt a safety curriculum was compatible with the values of their organisation; however, important faculty-level barriers to patient safety curriculum implementation were identified. Key structural markers, such as dedicated financial resources and relevant assessment tools to evaluate trainees' patient safety knowledge and skills, were in place in fewer than half of organisations studied. Greater attention to patient safety curriculum implementation is needed. The barriers to patient safety curriculum implementation we identified in LMICs are not unique to these regions. We propose a framework to act as a global standard for patient safety curriculum implementation. Educating leaders through the system in

  4. Two stage treatment of dairy effluent using immobilized Chlorella pyrenoidosa

    Science.gov (United States)

    2013-01-01

    Background Dairy effluents contains high organic load and unscrupulous discharge of these effluents into aquatic bodies is a matter of serious concern besides deteriorating their water quality. Whilst physico-chemical treatment is the common mode of treatment, immobilized microalgae can be potentially employed to treat high organic content which offer numerous benefits along with waste water treatment. Methods A novel low cost two stage treatment was employed for the complete treatment of dairy effluent. The first stage consists of treating the diary effluent in a photobioreactor (1 L) using immobilized Chlorella pyrenoidosa while the second stage involves a two column sand bed filtration technique. Results Whilst NH4+-N was completely removed, a 98% removal of PO43--P was achieved within 96 h of two stage purification processes. The filtrate was tested for toxicity and no mortality was observed in the zebra fish which was used as a model at the end of 96 h bioassay. Moreover, a significant decrease in biological oxygen demand and chemical oxygen demand was achieved by this novel method. Also the biomass separated was tested as a biofertilizer to the rice seeds and a 30% increase in terms of length of root and shoot was observed after the addition of biomass to the rice plants. Conclusions We conclude that the two stage treatment of dairy effluent is highly effective in removal of BOD and COD besides nutrients like nitrates and phosphates. The treatment also helps in discharging treated waste water safely into the receiving water bodies since it is non toxic for aquatic life. Further, the algal biomass separated after first stage of treatment was highly capable of increasing the growth of rice plants because of nitrogen fixation ability of the green alga and offers a great potential as a biofertilizer. PMID:24355316

  5. Two-Stage Fan I: Aerodynamic and Mechanical Design

    Science.gov (United States)

    Messenger, H. E.; Kennedy, E. E.

    1972-01-01

    A two-stage, highly-loaded fan was designed to deliver an overall pressure ratio of 2.8 with an adiabatic efficiency of 83.9 percent. At the first rotor inlet, design flow per unit annulus area is 42 lbm/sec/sq ft (205 kg/sec/sq m), hub/tip ratio is 0.4 with a tip diameter of 31 inches (0.787 m), and design tip speed is 1450 ft/sec (441.96 m/sec). Other features include use of multiple-circular-arc airfoils, resettable stators, and split casings over the rotor tip sections for casing treatment tests.

  6. Two-stage, high power X-band amplifier experiment

    International Nuclear Information System (INIS)

    Kuang, E.; Davis, T.J.; Ivers, J.D.; Kerslick, G.S.; Nation, J.A.; Schaechter, L.

    1993-01-01

    At output powers in excess of 100 MW the authors have noted the development of sidebands in many TWT structures. To address this problem an experiment using a narrow bandwidth, two-stage TWT is in progress. The TWT amplifier consists of a dielectric (e = 5) slow-wave structure, a 30 dB sever section and a 8.8-9.0 GHz passband periodic, metallic structure. The electron beam used in this experiment is a 950 kV, 1 kA, 50 ns pencil beam propagating along an applied axial field of 9 kG. The dielectric first stage has a maximum gain of 30 dB measured at 8.87 GHz, with output powers of up to 50 MW in the TM 01 mode. In these experiments the dielectric amplifier output power is about 3-5 MW and the output power of the complete two-stage device is ∼160 MW at the input frequency. The sidebands detected in earlier experiments have been eliminated. The authors also report measurements of the energy spread of the electron beam resulting from the amplification process. These experimental results are compared with MAGIC code simulations and analytic work they have carried out on such devices

  7. Two-stage liquefaction of a Spanish subbituminous coal

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, M.T.; Fernandez, I.; Benito, A.M.; Cebolla, V.; Miranda, J.L.; Oelert, H.H. (Instituto de Carboquimica, Zaragoza (Spain))

    1993-05-01

    A Spanish subbituminous coal has been processed in two-stage liquefaction in a non-integrated process. The first-stage coal liquefaction has been carried out in a continuous pilot plant in Germany at Clausthal Technical University at 400[degree]C, 20 MPa hydrogen pressure and anthracene oil as solvent. The second-stage coal liquefaction has been performed in continuous operation in a hydroprocessing unit at the Instituto de Carboquimica at 450[degree]C and 10 MPa hydrogen pressure, with two commercial catalysts: Harshaw HT-400E (Co-Mo/Al[sub 2]O[sub 3]) and HT-500E (Ni-Mo/Al[sub 2]O[sub 3]). The total conversion for the first-stage coal liquefaction was 75.41 wt% (coal d.a.f.), being 3.79 wt% gases, 2.58 wt% primary condensate and 69.04 wt% heavy liquids. The heteroatoms removal for the second-stage liquefaction was 97-99 wt% of S, 85-87 wt% of N and 93-100 wt% of O. The hydroprocessed liquids have about 70% of compounds with boiling point below 350[degree]C, and meet the sulphur and nitrogen specifications for refinery feedstocks. Liquids from two-stage coal liquefaction have been distilled, and the naphtha, kerosene and diesel fractions obtained have been characterized. 39 refs., 3 figs., 8 tabs.

  8. Two-stage perceptual learning to break visual crowding.

    Science.gov (United States)

    Zhu, Ziyun; Fan, Zhenzhi; Fang, Fang

    2016-01-01

    When a target is presented with nearby flankers in the peripheral visual field, it becomes harder to identify, which is referred to as crowding. Crowding sets a fundamental limit of object recognition in peripheral vision, preventing us from fully appreciating cluttered visual scenes. We trained adult human subjects on a crowded orientation discrimination task and investigated whether crowding could be completely eliminated by training. We discovered a two-stage learning process with this training task. In the early stage, when the target and flankers were separated beyond a certain distance, subjects acquired a relatively general ability to break crowding, as evidenced by the fact that the breaking of crowding could transfer to another crowded orientation, even a crowded motion stimulus, although the transfer to the opposite visual hemi-field was weak. In the late stage, like many classical perceptual learning effects, subjects' performance gradually improved and showed specificity to the trained orientation. We also found that, when the target and flankers were spaced too finely, training could only reduce, rather than completely eliminate, the crowding effect. This two-stage learning process illustrates a learning strategy for our brain to deal with the notoriously difficult problem of identifying peripheral objects in clutter. The brain first learned to solve the "easy and general" part of the problem (i.e., improving the processing resolution and segmenting the target and flankers) and then tackle the "difficult and specific" part (i.e., refining the representation of the target).

  9. Runway Operations Planning: A Two-Stage Heuristic Algorithm

    Science.gov (United States)

    Anagnostakis, Ioannis; Clarke, John-Paul

    2003-01-01

    The airport runway is a scarce resource that must be shared by different runway operations (arrivals, departures and runway crossings). Given the possible sequences of runway events, careful Runway Operations Planning (ROP) is required if runway utilization is to be maximized. From the perspective of departures, ROP solutions are aircraft departure schedules developed by optimally allocating runway time for departures given the time required for arrivals and crossings. In addition to the obvious objective of maximizing throughput, other objectives, such as guaranteeing fairness and minimizing environmental impact, can also be incorporated into the ROP solution subject to constraints introduced by Air Traffic Control (ATC) procedures. This paper introduces a two stage heuristic algorithm for solving the Runway Operations Planning (ROP) problem. In the first stage, sequences of departure class slots and runway crossings slots are generated and ranked based on departure runway throughput under stochastic conditions. In the second stage, the departure class slots are populated with specific flights from the pool of available aircraft, by solving an integer program with a Branch & Bound algorithm implementation. Preliminary results from this implementation of the two-stage algorithm on real-world traffic data are presented.

  10. TWO-STAGE HEAT PUMPS FOR ENERGY SAVING TECHNOLOGIES

    Directory of Open Access Journals (Sweden)

    A. E. Denysova

    2017-09-01

    Full Text Available The problem of energy saving becomes one of the most important in power engineering. It is caused by exhaustion of world reserves in hydrocarbon fuel, such as gas, oil and coal representing sources of traditional heat supply. Conventional sources have essential shortcomings: low power, ecological and economic efficiencies, that can be eliminated by using alternative methods of power supply, like the considered one: low-temperature natural heat of ground waters of on the basis of heat pump installations application. The heat supply system considered provides an effective use of two stages heat pump installation operating as heat source at ground waters during the lowest ambient temperature period. Proposed is a calculation method of heat pump installations on the basis of groundwater energy. Calculated are the values of electric energy consumption by the compressors’ drive, and the heat supply system transformation coefficient µ for a low-potential source of heat from ground waters allowing to estimate high efficiency of two stages heat pump installations.

  11. Two stage approach to dynamic soil structure interaction

    International Nuclear Information System (INIS)

    Nelson, I.

    1981-01-01

    A two stage approach is used to reduce the effective size of soil island required to solve dynamic soil structure interaction problems. The ficticious boundaries of the conventional soil island are chosen sufficiently far from the structure so that the presence of the structure causes only a slight perturbation on the soil response near the boundaries. While the resulting finite element model of the soil structure system can be solved, it requires a formidable computational effort. Currently, a two stage approach is used to reduce this effort. The combined soil structure system has many frequencies and wavelengths. For a stiff structure, the lowest frequencies are those associated with the motion of the structure as a rigid body. In the soil, these modes have the longest wavelengths and attenuate most slowly. The higher frequency deformational modes of the structure have shorter wavelengths and their effect attenuates more rapidly with distance from the structure. The difference in soil response between a computation with a refined structural model, and one with a crude model, tends towards zero a very short distance from the structure. In the current work, the 'crude model' is a rigid structure with the same geometry and inertial properties as the refined model. Preliminary calculations indicated that a rigid structure would be a good low frequency approximation to the actual structure, provided the structure was much stiffer than the native soil. (orig./RW)

  12. Repetitive, small-bore two-stage light gas gun

    International Nuclear Information System (INIS)

    Combs, S.K.; Foust, C.R.; Fehling, D.T.; Gouge, M.J.; Milora, S.L.

    1991-01-01

    A repetitive two-stage light gas gun for high-speed pellet injection has been developed at Oak Ridge National Laboratory. In general, applications of the two-stage light gas gun have been limited to only single shots, with a finite time (at least minutes) needed for recovery and preparation for the next shot. The new device overcomes problems associated with repetitive operation, including rapidly evacuating the propellant gases, reloading the gun breech with a new projectile, returning the piston to its initial position, and refilling the first- and second-stage gas volumes to the appropriate pressure levels. In addition, some components are subjected to and must survive severe operating conditions, which include rapid cycling to high pressures and temperatures (up to thousands of bars and thousands of kelvins) and significant mechanical shocks. Small plastic projectiles (4-mm nominal size) and helium gas have been used in the prototype device, which was equipped with a 1-m-long pump tube and a 1-m-long gun barrel, to demonstrate repetitive operation (up to 1 Hz) at relatively high pellet velocities (up to 3000 m/s). The equipment is described, and experimental results are presented. 124 refs., 6 figs., 5 tabs

  13. Simultaneous versus sequential pharmacokinetic-pharmacodynamic population analysis using an iterative two-stage Bayesian technique

    NARCIS (Netherlands)

    Proost, Johannes H.; Schiere, Sjouke; Eleveld, Douglas J.; Wierda, J. Mark K. H.

    A method for simultaneous pharmacokinetic-pharmacodynamic (PK-PD) population analysis using an Iterative Two-Stage Bayesian (ITSB) algorithm was developed. The method was evaluated using clinical data and Monte Carlo simulations. Data from a clinical study with rocuronium in nine anesthetized

  14. Numerical simulation of brain tumor growth model using two-stage ...

    African Journals Online (AJOL)

    In the recent years, the study of glioma growth to be an active field of research Mathematical models that describe the proliferation and diffusion properties of the growth have been developed by many researchers. In this work, the performance analysis of two-stage Gauss-Seidel (TSGS) method to solve the glioma growth ...

  15. Two-stage bargaining with coverage extension in a dual labour market

    DEFF Research Database (Denmark)

    Roberts, Mark A.; Stæhr, Karsten; Tranæs, Torben

    2000-01-01

    This paper studies coverage extension in a simple general equilibrium model with a dual labour market. The union sector is characterized by two-stage bargaining whereas the firms set wages in the non-union sector. In this model firms and unions of the union sector have a commonality of interest...

  16. The RTD measurement of two stage anaerobic digester using radiotracer in WWTP

    International Nuclear Information System (INIS)

    Jin-Seop, Kim; Jong-Bum, Kim; Sung-Hee, Jung

    2006-01-01

    The aims of this study are to assess the existence and location of the stagnant zone by estimating the MRT (mean residence time) on the two stage anaerobic digester, with the results to be used as informative clue for its better operation

  17. A two-stage meta-analysis identifies several new loci for Parkinson's disease.

    NARCIS (Netherlands)

    Plagnol, V.; Nalls, M.A.; Bras, J.M.; Hernandez, D.; Sharma, M.; Sheerin, U.M.; Saad, M.; Simon-Sanchez, J.; Schulte, C.; Lesage, S.; Sveinbjornsdottir, S.; Amouyel, P.; Arepalli, S.; Band, G.; Barker, R.A.; Bellinguez, C.; Ben-Shlomo, Y.; Berendse, H.W.; Berg, D; Bhatia, K.P.; Bie, R.M. de; Biffi, A.; Bloem, B.R.; Bochdanovits, Z.; Bonin, M.; Brockmann, K.; Brooks, J.; Burn, D.J.; Charlesworth, G.; Chen, H.; Chinnery, P.F.; Chong, S.; Clarke, C.E.; Cookson, M.R.; Cooper, J.M.; Corvol, J.C.; Counsell, J.; Damier, P.; Dartigues, J.F.; Deloukas, P.; Deuschl, G.; Dexter, D.T.; Dijk, K.D. van; Dillman, A.; Durif, F.; Durr, A.; Edkins, S.; Evans, J.R.; Foltynie, T.; Freeman, C.; Gao, J.; Gardner, M.; Gibbs, J.R.; Goate, A.; Gray, E.; Guerreiro, R.; Gustafsson, O.; Harris, C.; Hellenthal, G.; Hilten, J.J. van; Hofman, A.; Hollenbeck, A.; Holton, J.L.; Hu, M.; Huang, X.; Huber, H; Hudson, G.; Hunt, S.E.; Huttenlocher, J.; Illig, T.; Jonsson, P.V.; Langford, C.; Lees, A.J.; Lichtner, P.; Limousin, P.; Lopez, G.; McNeill, A.; Moorby, C.; Moore, M.; Morris, H.A.; Morrison, K.E.; Mudanohwo, E.; O'Sullivan, S.S; Pearson, J.; Pearson, R.; Perlmutter, J.; Petursson, H.; Pirinen, M.; Polnak, P.; Post, B.; Potter, S.C.; Ravina, B.; Revesz, T.; Riess, O.; Rivadeneira, F.; Rizzu, P.; Ryten, M.; Sawcer, S.J.; Schapira, A.; Scheffer, H.; Shaw, K.; Shoulson, I.; Sidransky, E.; Silva, R. de; Smith, C.; Spencer, C.C.; Stefansson, H.; Steinberg, S.; Stockton, J.D.; Strange, A.; Su, Z.; Talbot, K.; Tanner, C.M.; Tashakkori-Ghanbaria, A.; Tison, F.; Trabzuni, D.; Traynor, B.J.; Uitterlinden, A.G.; Vandrovcova, J.; Velseboer, D.; Vidailhet, M.; Vukcevic, D.; Walker, R.; Warrenburg, B.P.C. van de; Weale, M.E.; Wickremaratchi, M.; Williams, N.; Williams-Gray, C.H.; Winder-Rhodes, S.; Stefansson, K.; Martinez, M.; Donnelly, P.; Singleton, A.B.; Hardy, J.; Heutink, P.; Brice, A.; Gasser, T.; Wood, N.W.

    2011-01-01

    A previous genome-wide association (GWA) meta-analysis of 12,386 PD cases and 21,026 controls conducted by the International Parkinson's Disease Genomics Consortium (IPDGC) discovered or confirmed 11 Parkinson's disease (PD) loci. This first analysis of the two-stage IPDGC study

  18. Advancing early detection of autism spectrum disorder by applying an integrated two-stage screening approach

    NARCIS (Netherlands)

    Oosterling, Iris J.; Wensing, Michel; Swinkels, Sophie H.; van der Gaag, Rutger Jan; Visser, Janne C.; Woudenberg, Tim; Minderaa, Ruud; Steenhuis, Mark-Peter; Buitelaar, Jan K.

    Background: Few field trials exist on the impact of implementing guidelines for the early detection of autism spectrum disorders (ASD). The aims of the present study were to develop and evaluate a clinically relevant integrated early detection programme based on the two-stage screening approach of

  19. A Two-Stage Meta-Analysis Identifies Several New Loci for Parkinson's Disease

    NARCIS (Netherlands)

    Plagnol, Vincent; Nalls, Michael A.; Bras, Jose M.; Hernandez, Dena G.; Sharma, Manu; Sheerin, Una-Marie; Saad, Mohamad; Simon-Sanchez, Javier; Schulte, Claudia; Lesage, Suzanne; Sveinbjornsdottir, Sigurlaug; Amouyel, Philippe; Arepalli, Sampath; Band, Gavin; Barker, Roger A.; Bellinguez, Celine; Ben-Shlomo, Yoav; Berendse, Henk W.; Berg, Daniela; Bhatia, Kailash; de Bie, Rob M. A.; Biffi, Alessandro; Bloem, Bas; Bochdanovits, Zoltan; Bonin, Michael; Brockmann, Kathrin; Brooks, Janet; Burn, David J.; Charlesworth, Gavin; Chen, Honglei; Chinnery, Patrick F.; Chong, Sean; Clarke, Carl E.; Cookson, Mark R.; Cooper, J. Mark; Corvol, Jean Christophe; Counsell, Carl; Damier, Philippe; Dartigues, Jean-Francois; Deloukas, Panos; Deuschl, Guenther; Dexter, David T.; van Dijk, Karin D.; Dillman, Allissa; Durif, Frank; Duerr, Alexandra; Edkins, Sarah; Evans, Jonathan R.; Foltynie, Thomas; Freeman, Colin; Gao, Jianjun; Gardner, Michelle; Gibbs, J. Raphael; Goate, Alison; Gray, Emma; Guerreiro, Rita; Gustafsson, Omar; Harris, Clare; Hellenthal, Garrett; van Hilten, Jacobus J.; Hofman, Albert; Hollenbeck, Albert; Holton, Janice; Hu, Michele; Huang, Xuemei; Huber, Heiko; Hudson, Gavin; Hunt, Sarah E.; Huttenlocher, Johanna; Illig, Thomas; Jonsson, Palmi V.; Langford, Cordelia; Lees, Andrew; Lichtner, Peter; Limousin, Patricia; Lopez, Grisel; Lorenz, Delia; McNeill, Alisdair; Moorby, Catriona; Moore, Matthew; Morris, Huw; Morrison, Karen E.; Mudanohwo, Ese; O'Sullivan, Sean S.; Pearson, Justin; Pearson, Richard; Perlmutter, Joel S.; Petursson, Hjoervar; Pirinen, Matti; Pollak, Pierre; Post, Bart; Potter, Simon; Ravina, Bernard; Revesz, Tamas; Riess, Olaf; Rivadeneira, Fernando; Rizzu, Patrizia; Ryten, Mina; Sawcer, Stephen; Schapira, Anthony; Scheffer, Hans; Shaw, Karen; Shoulson, Ira; Sidransky, Ellen; de Silva, Rohan; Smith, Colin; Spencer, Chris C. A.; Stefansson, Hreinn; Steinberg, Stacy; Stockton, Joanna D.; Strange, Amy; Su, Zhan; Talbot, Kevin; Tanner, Carlie M.; Tashakkori-Ghanbaria, Avazeh; Tison, Francois; Trabzuni, Daniah; Traynor, Bryan J.; Uitterlinden, Andre G.; Vandrovcova, Jana; Velseboer, Daan; Vidailhet, Marie; Vukcevic, Damjan; Walker, Robert; van de Warrenburg, Bart; Weale, Michael E.; Wickremaratchi, Mirdhu; Williams, Nigel; Williams-Gray, Caroline H.; Winder-Rhodes, Sophie; Stefansson, Kari; Martinez, Maria; Donnelly, Peter; Singleton, Andrew B.; Hardy, John; Heutink, Peter; Brice, Alexis; Gasser, Thomas; Wood, Nicholas W.

    2011-01-01

    A previous genome-wide association (GWA) meta-analysis of 12,386 PD cases and 21,026 controls conducted by the International Parkinson's Disease Genomics Consortium (IPDGC) discovered or confirmed 11 Parkinson's disease (PD) loci. This first analysis of the two-stage IPDGC study focused on the set

  20. On the prior probabilities for two-stage Bayesian estimates

    International Nuclear Information System (INIS)

    Kohut, P.

    1992-01-01

    The method of Bayesian inference is reexamined for its applicability and for the required underlying assumptions in obtaining and using prior probability estimates. Two different approaches are suggested to determine the first-stage priors in the two-stage Bayesian analysis which avoid certain assumptions required for other techniques. In the first scheme, the prior is obtained through a true frequency based distribution generated at selected intervals utilizing actual sampling of the failure rate distributions. The population variability distribution is generated as the weighed average of the frequency distributions. The second method is based on a non-parametric Bayesian approach using the Maximum Entropy Principle. Specific features such as integral properties or selected parameters of prior distributions may be obtained with minimal assumptions. It is indicated how various quantiles may also be generated with a least square technique

  1. Two-stage hydroprocessing of synthetic crude gas oil

    Energy Technology Data Exchange (ETDEWEB)

    Mahay, A.; Chmielowiec, J.; Fisher, I.P.; Monnier, J. (Petro-Canada Products, Missisauga, ON (Canada). Research and Development Centre)

    1992-02-01

    The hydrocracking of synthetic crude gas oils (SGO), which are commercially produced from Canadian oil sands, is strongly inhibited by nitrogen-containing species. To alleviate the pronounced effect of these nitrogenous compounds, SGO was hydrotreated at severe conditions prior to hydrocracking to reduce its N content from 1665 to about 390 ppm (by weight). Hydrocracking was then performed using a commercial nickel-tungsten catalyst supported on silica-alumina. Two-stage hydroprocessing of SGO was assessed in terms of product yields and quality. As expected, higher gas oil conversion were achieved mostly from an increase in naphtha yield. The middle distillate product quality was also clearly improved as the diesel fuel cetane number increased by 13%. Diesel engine tests indicated that particulate emissions in exhaust gases were lowered by 20%. Finally, pseudo first-order kinetic equations were derived for the overall conversion of the major gas oil components. 17 refs., 2 figs., 8 tabs.

  2. Quick pace of property acquisitions requires two-stage evaluations

    International Nuclear Information System (INIS)

    Hollo, R.; Lockwood, S.

    1994-01-01

    The traditional method of evaluating oil and gas reserves may be too cumbersome for the quick pace of oil and gas property acquisition. An acquisition evaluator must decide quickly if a property meets basic purchase criteria. The current business climate requires a two-stage approach. First, the evaluator makes a quick assessment of the property and submits a bid. If the bid is accepted then the evaluator goes on with a detailed analysis, which represents the second stage. Acquisition of producing properties has become an important activity for many independent oil and gas producers, who must be able to evaluate reserves quickly enough to make effective business decisions yet accurately enough to avoid costly mistakes. Independent thus must be familiar with how transactions usually progress as well as with the basic methods of property evaluation. The paper discusses acquisition activity, the initial offer, the final offer, property evaluation, and fair market value

  3. GENERALISED MODEL BASED CONFIDENCE INTERVALS IN TWO STAGE CLUSTER SAMPLING

    Directory of Open Access Journals (Sweden)

    Christopher Ouma Onyango

    2010-09-01

    Full Text Available Chambers and Dorfman (2002 constructed bootstrap confidence intervals in model based estimation for finite population totals assuming that auxiliary values are available throughout a target population and that the auxiliary values are independent. They also assumed that the cluster sizes are known throughout the target population. We now extend to two stage sampling in which the cluster sizes are known only for the sampled clusters, and we therefore predict the unobserved part of the population total. Jan and Elinor (2008 have done similar work, but unlike them, we use a general model, in which the auxiliary values are not necessarily independent. We demonstrate that the asymptotic properties of our proposed estimator and its coverage rates are better than those constructed under the model assisted local polynomial regression model.

  4. Two-Stage Part-Based Pedestrian Detection

    DEFF Research Database (Denmark)

    Møgelmose, Andreas; Prioletti, Antonio; Trivedi, Mohan M.

    2012-01-01

    Detecting pedestrians is still a challenging task for automotive vision system due the extreme variability of targets, lighting conditions, occlusions, and high speed vehicle motion. A lot of research has been focused on this problem in the last 10 years and detectors based on classifiers has...... gained a special place among the different approaches presented. This work presents a state-of-the-art pedestrian detection system based on a two stages classifier. Candidates are extracted with a Haar cascade classifier trained with the DaimlerDB dataset and then validated through part-based HOG...... of several metrics, such as detection rate, false positives per hour, and frame rate. The novelty of this system rely in the combination of HOG part-based approach, tracking based on specific optimized feature and porting on a real prototype....

  5. Device for two-stage cementing of casing

    Energy Technology Data Exchange (ETDEWEB)

    Kudimov, D A; Goncharevskiy, Ye N; Luneva, L G; Shchelochkov, S N; Shil' nikova, L N; Tereshchenko, V G; Vasiliev, V A; Volkova, V V; Zhdokov, K I

    1981-01-01

    A device is claimed for two-stage cementing of casing. It consists of a body with lateral plugging vents, upper and lower movable sleeves, a check valve with axial channels that's situated in the lower sleeve, and a displacement limiting device for the lower sleeve. To improve the cementing process of the casing by preventing overflow of cementing fluids from the annular space into the first stage casing, the limiter is equipped with a spring rod that is capable of covering the axial channels of the check valve while it's in an operating mode. In addition, the rod in the upper part is equipped with a reinforced area under the axial channels of the check valve.

  6. Two-stage decision approach to material accounting

    International Nuclear Information System (INIS)

    Opelka, J.H.; Sutton, W.B.

    1982-01-01

    The validity of the alarm threshold 4sigma has been checked for hypothetical large and small facilities using a two-stage decision model in which the diverter's strategic variable is the quantity diverted, and the defender's strategic variables are the alarm threshold and the effectiveness of the physical security and material control systems in the possible presence of a diverter. For large facilities, the material accounting system inherently appears not to be a particularly useful system for the deterrence of diversions, and essentially no improvement can be made by lowering the alarm threshold below 4sigma. For small facilities, reduction of the threshold to 2sigma or 3sigma is a cost effective change for the accounting system, but is probably less cost effective than making improvements in the material control and physical security systems

  7. The hybrid two stage anticlockwise cycle for ecological energy conversion

    Directory of Open Access Journals (Sweden)

    Cyklis Piotr

    2016-01-01

    Full Text Available The anticlockwise cycle is commonly used for refrigeration, air conditioning and heat pumps applications. The application of refrigerant in the compression cycle is within the temperature limits of the triple point and the critical point. New refrigerants such as 1234yf or 1234ze have many disadvantages, therefore natural refrigerants application is favourable. The carbon dioxide and water can be applied only in the hybrid two stages cycle. The possibilities of this solutions are shown for refrigerating applications, as well some experimental results of the adsorption-compression double stages cycle, powered with solar collectors are shown. As a high temperature cycle the adsorption system is applied. The low temperature cycle is the compression stage with carbon dioxide as a working fluid. This allows to achieve relatively high COP for low temperature cycle and for the whole system.

  8. High Performance Gasification with the Two-Stage Gasifier

    DEFF Research Database (Denmark)

    Gøbel, Benny; Hindsgaul, Claus; Henriksen, Ulrik Birk

    2002-01-01

    , air preheating and pyrolysis, hereby very high energy efficiencies can be achieved. Encouraging results are obtained at a 100 kWth laboratory facility. The tar content in the raw gas is measured to be below 25 mg/Nm3 and around 5 mg/Nm3 after gas cleaning with traditional baghouse filter. Furthermore...... a cold gas efficiency exceeding 90% is obtained. In the original design of the two-stage gasification process, the pyrolysis unit consists of a screw conveyor with external heating, and the char unit is a fixed bed gasifier. This design is well proven during more than 1000 hours of testing with various...... fuels, and is a suitable design for medium size gasifiers....

  9. A two-stage method for inverse medium scattering

    KAUST Repository

    Ito, Kazufumi

    2013-03-01

    We present a novel numerical method to the time-harmonic inverse medium scattering problem of recovering the refractive index from noisy near-field scattered data. The approach consists of two stages, one pruning step of detecting the scatterer support, and one resolution enhancing step with nonsmooth mixed regularization. The first step is strictly direct and of sampling type, and it faithfully detects the scatterer support. The second step is an innovative application of nonsmooth mixed regularization, and it accurately resolves the scatterer size as well as intensities. The nonsmooth model can be efficiently solved by a semi-smooth Newton-type method. Numerical results for two- and three-dimensional examples indicate that the new approach is accurate, computationally efficient, and robust with respect to data noise. © 2012 Elsevier Inc.

  10. Treatment of corn ethanol distillery wastewater using two-stage anaerobic digestion.

    Science.gov (United States)

    Ráduly, B; Gyenge, L; Szilveszter, Sz; Kedves, A; Crognale, S

    In this study the mesophilic two-stage anaerobic digestion (AD) of corn bioethanol distillery wastewater is investigated in laboratory-scale reactors. Two-stage AD technology separates the different sub-processes of the AD in two distinct reactors, enabling the use of optimal conditions for the different microbial consortia involved in the different process phases, and thus allowing for higher applicable organic loading rates (OLRs), shorter hydraulic retention times (HRTs) and better conversion rates of the organic matter, as well as higher methane content of the produced biogas. In our experiments the reactors have been operated in semi-continuous phase-separated mode. A specific methane production of 1,092 mL/(L·d) has been reached at an OLR of 6.5 g TCOD/(L·d) (TCOD: total chemical oxygen demand) and a total HRT of 21 days (5.7 days in the first-stage, and 15.3 days in the second-stage reactor). Nonetheless the methane concentration in the second-stage reactor was very high (78.9%); the two-stage AD outperformed the reference single-stage AD (conducted at the same reactor loading rate and retention time) by only a small margin in terms of volumetric methane production rate. This makes questionable whether the higher methane content of the biogas counterbalances the added complexity of the two-stage digestion.

  11. Runway Operations Planning: A Two-Stage Solution Methodology

    Science.gov (United States)

    Anagnostakis, Ioannis; Clarke, John-Paul

    2003-01-01

    The airport runway is a scarce resource that must be shared by different runway operations (arrivals, departures and runway crossings). Given the possible sequences of runway events, careful Runway Operations Planning (ROP) is required if runway utilization is to be maximized. Thus, Runway Operations Planning (ROP) is a critical component of airport operations planning in general and surface operations planning in particular. From the perspective of departures, ROP solutions are aircraft departure schedules developed by optimally allocating runway time for departures given the time required for arrivals and crossings. In addition to the obvious objective of maximizing throughput, other objectives, such as guaranteeing fairness and minimizing environmental impact, may be incorporated into the ROP solution subject to constraints introduced by Air Traffic Control (ATC) procedures. Generating optimal runway operations plans was approached in with a 'one-stage' optimization routine that considered all the desired objectives and constraints, and the characteristics of each aircraft (weight class, destination, Air Traffic Control (ATC) constraints) at the same time. Since, however, at any given point in time, there is less uncertainty in the predicted demand for departure resources in terms of weight class than in terms of specific aircraft, the ROP problem can be parsed into two stages. In the context of the Departure Planner (OP) research project, this paper introduces Runway Operations Planning (ROP) as part of the wider Surface Operations Optimization (SOO) and describes a proposed 'two stage' heuristic algorithm for solving the Runway Operations Planning (ROP) problem. Focus is specifically given on including runway crossings in the planning process of runway operations. In the first stage, sequences of departure class slots and runwy crossings slots are generated and ranked based on departure runway throughput under stochastic conditions. In the second stage, the

  12. A Longitudinal Study of Usability in Health Care

    DEFF Research Database (Denmark)

    Kjeldskov, Jesper; Skov, Mikael B.; Stage, Jan

    2010-01-01

    We report from a longitudinal laboratory-based usability evaluation of a health care information system. The purpose of the study was to inquire into the nature of usability problems experienced by novice and expert users, and to see to what extend usability problems of a health care information...... system may or may not disappear over time, as the nurses get more familiar with it-if time heals poor design? As our method for studying this, we conducted a longitudinal study with two key studies. A usability evaluation was conducted with novice users when an electronic patient record system was being......, we discuss implications for evaluating usability in health care....

  13. Two-Stage Electricity Demand Modeling Using Machine Learning Algorithms

    Directory of Open Access Journals (Sweden)

    Krzysztof Gajowniczek

    2017-10-01

    Full Text Available Forecasting of electricity demand has become one of the most important areas of research in the electric power industry, as it is a critical component of cost-efficient power system management and planning. In this context, accurate and robust load forecasting is supposed to play a key role in reducing generation costs, and deals with the reliability of the power system. However, due to demand peaks in the power system, forecasts are inaccurate and prone to high numbers of errors. In this paper, our contributions comprise a proposed data-mining scheme for demand modeling through peak detection, as well as the use of this information to feed the forecasting system. For this purpose, we have taken a different approach from that of time series forecasting, representing it as a two-stage pattern recognition problem. We have developed a peak classification model followed by a forecasting model to estimate an aggregated demand volume. We have utilized a set of machine learning algorithms to benefit from both accurate detection of the peaks and precise forecasts, as applied to the Polish power system. The key finding is that the algorithms can detect 96.3% of electricity peaks (load value equal to or above the 99th percentile of the load distribution and deliver accurate forecasts, with mean absolute percentage error (MAPE of 3.10% and resistant mean absolute percentage error (r-MAPE of 2.70% for the 24 h forecasting horizon.

  14. FIRST DIRECT EVIDENCE OF TWO STAGES IN FREE RECALL

    Directory of Open Access Journals (Sweden)

    Eugen Tarnow

    2015-12-01

    Full Text Available I find that exactly two stages can be seen directly in sequential free recall distributions. These distributions show that the first three recalls come from the emptying of working memory, recalls 6 and above come from a second stage and the 4th and 5th recalls are mixtures of the two.A discontinuity, a rounded step function, is shown to exist in the fitted linear slope of the recall distributions as the recall shifts from the emptying of working memory (positive slope to the second stage (negative slope. The discontinuity leads to a first estimate of the capacity of working memory at 4-4.5 items. The total recall is shown to be a linear combination of the content of working memory and items recalled in the second stage with 3.0-3.9 items coming from working memory, a second estimate of the capacity of working memory. A third, separate upper limit on the capacity of working memory is found (3.06 items, corresponding to the requirement that the content of working memory cannot exceed the total recall, item by item. This third limit is presumably the best limit on the average capacity of unchunked working memory.The second stage of recall is shown to be reactivation: The average times to retrieve additional items in free recall obey a linear relationship as a function of the recall probability which mimics recognition and cued recall, both mechanisms using reactivation (Tarnow, 2008.

  15. A two-stage DEA approach for environmental efficiency measurement.

    Science.gov (United States)

    Song, Malin; Wang, Shuhong; Liu, Wei

    2014-05-01

    The slacks-based measure (SBM) model based on the constant returns to scale has achieved some good results in addressing the undesirable outputs, such as waste water and water gas, in measuring environmental efficiency. However, the traditional SBM model cannot deal with the scenario in which desirable outputs are constant. Based on the axiomatic theory of productivity, this paper carries out a systematic research on the SBM model considering undesirable outputs, and further expands the SBM model from the perspective of network analysis. The new model can not only perform efficiency evaluation considering undesirable outputs, but also calculate desirable and undesirable outputs separately. The latter advantage successfully solves the "dependence" problem of outputs, that is, we can not increase the desirable outputs without producing any undesirable outputs. The following illustration shows that the efficiency values obtained by two-stage approach are smaller than those obtained by the traditional SBM model. Our approach provides a more profound analysis on how to improve environmental efficiency of the decision making units.

  16. Two-stage nuclear refrigeration with enhanced nuclear moments

    International Nuclear Information System (INIS)

    Hunik, R.

    1979-01-01

    Experiments are described in which an enhanced nuclear system is used as a precoolant for a nuclear demagnetisation stage. The results show the promising advantages of such a system in those circumstances for which a large cooling power is required at extremely low temperatures. A theoretical review of nuclear enhancement at the microscopic level and its macroscopic thermodynamical consequences is given. The experimental equipment for the implementation of the nuclear enhanced refrigeration method is described and the experiments on two-stage nuclear demagnetisation are discussed. With the nuclear enhanced system PrCu 6 the author could precool a nuclear stage of indium in a magnetic field of 6 T down to temperatures below 10 mK; this resulted in temperature below 1 mK after demagnetisation of the indium. It is demonstrated that the interaction energy between the nuclear moments in an enhanced nuclear system can exceed the nuclear dipolar interaction. Several experiments are described on pulsed nuclear magnetic resonance, as utilised for thermometry purposes. It is shown that platinum NMR-thermometry gives very satisfactory results around 1 mK. The results of experiments on nuclear orientation of radioactive nuclei, e.g. the brute force polarisation of 95 NbPt and 60 CoCu, are presented, some of which are of major importance for the thermometry in the milli-Kelvin region. (Auth.)

  17. LONGITUDINAL STUDIES OF MUSICALLY GIFTED SCHOOLGIRLS

    Directory of Open Access Journals (Sweden)

    Svetlana N. Loseva

    2016-01-01

    Full Text Available The aim of the article is to consider the empirical aspects of the development of musical gifted schoolgirls in vocal and choral activities.Methods. Scientific methods of research (observation, questionnaire, interview, formative experiment, longitude, testing are used. Data are analyzed using a complex of psychodiagnostic techniques: culture and free intelligence test by R. Cattell; the modified creative test by F. Williams; personal multifactorial questionnaire by R. Cattell. The reliability of the results and the validity of the findings is provided by the use of reliable and proven in the domestic and foreign psychology methods and techniques, using different statistical methods of data processing, the definition of parametric and non-parametric statistical tests (Student’s t-criterion, Spearman’s rank correlation, criterion U-Mann – Whitney, criterion T-Wilcoxon, L-criterion trends Page.Results and scientific novelty. Results of longitudinal research of development of musical aptitude are presented. Experimental work in which schoolgirls of 8–15 years participated, was carried out on the basis of creative choral collectives of Irkutsk within three years. Features of development of the pupils who are engaged in singing are revealed. It is established that in process of development of specially developed program (comprehension of emotional and semantic aspects of perception of a piece of music, finding of ability to distinguish musical timbres and the general coloring of sounding etc. analytical and intonation hearing improves under pupils’ age. Regular long singing trainings promote formation of cogitative operations: active development of divergent, rational and logical thinking and intelligence in general, and also acquisition of skills of a self-assessment. Besides, such occupations dispose children and teenagers to emotional responsiveness and spiritual self-improvement.Practical significance. The research

  18. Gas pollutants removal in a single- and two-stage ejector-venturi scrubber.

    Science.gov (United States)

    Gamisans, Xavier; Sarrà, Montserrrat; Lafuente, F Javier

    2002-03-29

    The absorption of SO(2) and NH(3) from the flue gas into NaOH and H(2)SO(4) solutions, respectively has been studied using an industrial scale ejector-venturi scrubber. A statistical methodology is presented to characterise the performance of the scrubber by varying several factors such as gas pollutant concentration, air flowrate and absorbing solution flowrate. Some types of venturi tube constructions were assessed, including the use of a two-stage venturi tube. The results showed a strong influence of the liquid scrubbing flowrate on pollutant removal efficiency. The initial pollutant concentration and the gas flowrate had a slight influence. The use of a two-stage venturi tube considerably improved the absorption efficiency, although it increased energy consumption. The results of this study will be applicable to the optimal design of venturi-based absorbers for gaseous pollution control or chemical reactors.

  19. Two-stage Catalytic Reduction of NOx with Hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Umit S. Ozkan; Erik M. Holmgreen; Matthew M. Yung; Jonathan Halter; Joel Hiltner

    2005-12-21

    A two-stage system for the catalytic reduction of NO from lean-burn natural gas reciprocating engine exhaust is investigated. Each of the two stages uses a distinct catalyst. The first stage is oxidation of NO to NO{sub 2} and the second stage is reduction of NO{sub 2} to N{sub 2} with a hydrocarbon. The central idea is that since NO{sub 2} is a more easily reduced species than NO, it should be better able to compete with oxygen for the combustion reaction of hydrocarbon, which is a challenge in lean conditions. Early work focused on demonstrating that the N{sub 2} yield obtained when NO{sub 2} was reduced was greater than when NO was reduced. NO{sub 2} reduction catalysts were designed and silver supported on alumina (Ag/Al{sub 2}O{sub 3}) was found to be quite active, able to achieve 95% N{sub 2} yield in 10% O{sub 2} using propane as the reducing agent. The design of a catalyst for NO oxidation was also investigated, and a Co/TiO{sub 2} catalyst prepared by sol-gel was shown to have high activity for the reaction, able to reach equilibrium conversion of 80% at 300 C at GHSV of 50,000h{sup -1}. After it was shown that NO{sub 2} could be more easily reduced to N{sub 2} than NO, the focus shifted on developing a catalyst that could use methane as the reducing agent. The Ag/Al{sub 2}O{sub 3} catalyst was tested and found to be inactive for NOx reduction with methane. Through iterative catalyst design, a palladium-based catalyst on a sulfated-zirconia support (Pd/SZ) was synthesized and shown to be able to selectively reduce NO{sub 2} in lean conditions using methane. Development of catalysts for the oxidation reaction also continued and higher activity, as well as stability in 10% water, was observed on a Co/ZrO{sub 2} catalyst, which reached equilibrium conversion of 94% at 250 C at the same GHSV. The Co/ZrO{sub 2} catalyst was also found to be extremely active for oxidation of CO, ethane, and propane, which could potential eliminate the need for any separate

  20. Causes for the two stages of the disruption energy quench

    Energy Technology Data Exchange (ETDEWEB)

    Schueller, F.C.; Donne, A.J.H.; Heijnen, S.H.; Rommers, J.R.; Tanzi, C.P. [FOM-Instituut voor Plasmafysica, Rijnhuizen (Netherlands); Vries, P.C. de; Waidmann, G. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Plasmaphysik

    1994-12-31

    It is a well-established fact that the energy quench of tokamak disruptions takes place in two stages separated by a plateau period. The total quench duration of typically a few hundred {mu}s is thought to be a combination of Alfven and magnetic diffusion times: Phase 1: a large cold m=1 bubble eats out the hot core within the q=1 surface. Since the normal thermal isolation of the outer layers is still intact this phase means an adiabatic flattening of the inner temperature distribution. Phase 2: after a plateau period the second quench occurs when the edge thermal barrier collapses and a major part of the plasma energy is lost in conjunction with a negative surface voltage spike and a positive spike of the plasma current. In the experimental and theoretical literature on this subject not much attention is given to the evolution of the density distribution during these two phases. This may be caused by the great difficulties one has to keep the fringe counters of multichannel interferometers on track during the very fast changing evolution. The interferometer at TEXTOR can follow this evolution. The spatial resolution after inversion is limited because of the modest number of interferometer channels. In RTP an 18-channel fast interferometer is available next to a 4-channel pulse radar reflectometer which makes it possible to investigate the density profile evolution with both good time (2 {mu}s)- and spatial (0.1a)-resolution. A fast 20-channel ECE-heterodyne radiometer and a 5-camera SXR system allows to follow the temperature profile evolution as well. In this paper theoretical models will be revisited and compared to the new experimental evidence. (author) 9 refs., 3 figs.

  1. Causes for the two stages of the disruption energy quench

    International Nuclear Information System (INIS)

    Schueller, F.C.; Donne, A.J.H.; Heijnen, S.H.; Rommers, J.R.; Tanzi, C.P.; Vries, P.C. de; Waidmann, G.

    1994-01-01

    It is a well-established fact that the energy quench of tokamak disruptions takes place in two stages separated by a plateau period. The total quench duration of typically a few hundred μs is thought to be a combination of Alfven and magnetic diffusion times: Phase 1: a large cold m=1 bubble eats out the hot core within the q=1 surface. Since the normal thermal isolation of the outer layers is still intact this phase means an adiabatic flattening of the inner temperature distribution. Phase 2: after a plateau period the second quench occurs when the edge thermal barrier collapses and a major part of the plasma energy is lost in conjunction with a negative surface voltage spike and a positive spike of the plasma current. In the experimental and theoretical literature on this subject not much attention is given to the evolution of the density distribution during these two phases. This may be caused by the great difficulties one has to keep the fringe counters of multichannel interferometers on track during the very fast changing evolution. The interferometer at TEXTOR can follow this evolution. The spatial resolution after inversion is limited because of the modest number of interferometer channels. In RTP an 18-channel fast interferometer is available next to a 4-channel pulse radar reflectometer which makes it possible to investigate the density profile evolution with both good time (2 μs)- and spatial (0.1a)-resolution. A fast 20-channel ECE-heterodyne radiometer and a 5-camera SXR system allows to follow the temperature profile evolution as well. In this paper theoretical models will be revisited and compared to the new experimental evidence. (author) 9 refs., 3 figs

  2. Transport fuels from two-stage coal liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Benito, A.; Cebolla, V.; Fernandez, I.; Martinez, M.T.; Miranda, J.L.; Oelert, H.; Prado, J.G. (Instituto de Carboquimica CSIC, Zaragoza (Spain))

    1994-03-01

    Four Spanish lignites and their vitrinite concentrates were evaluated for coal liquefaction. Correlationships between the content of vitrinite and conversion in direct liquefaction were observed for the lignites but not for the vitrinite concentrates. The most reactive of the four coals was processed in two-stage liquefaction at a higher scale. First-stage coal liquefaction was carried out in a continuous unit at Clausthal University at a temperature of 400[degree]C at 20 MPa hydrogen pressure and with anthracene oil as a solvent. The coal conversion obtained was 75.41% being 3.79% gases, 2.58% primary condensate and 69.04% heavy liquids. A hydroprocessing unit was built at the Instituto de Carboquimica for the second-stage coal liquefaction. Whole and deasphalted liquids from the first-stage liquefaction were processed at 450[degree]C and 10 MPa hydrogen pressure, with two commercial catalysts: Harshaw HT-400E (Co-Mo/Al[sub 2]O[sub 3]) and HT-500E (Ni-Mo/Al[sub 2]O[sub 3]). The effects of liquid hourly space velocity (LHSV), temperature, gas/liquid ratio and catalyst on the heteroatom liquids, and levels of 5 ppm of nitrogen and 52 ppm of sulphur were reached at 450[degree]C, 10 MPa hydrogen pressure, 0.08 kg H[sub 2]/kg feedstock and with Harshaw HT-500E catalyst. The liquids obtained were hydroprocessed again at 420[degree]C, 10 MPa hydrogen pressure and 0.06 kg H[sub 2]/kg feedstock to hydrogenate the aromatic structures. In these conditions, the aromaticity was reduced considerably, and 39% of naphthas and 35% of kerosene fractions were obtained. 18 refs., 4 figs., 4 tabs.

  3. Two-Stage Performance Engineering of Container-based Virtualization

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2018-02-01

    Full Text Available Cloud computing has become a compelling paradigm built on compute and storage virtualization technologies. The current virtualization solution in the Cloud widely relies on hypervisor-based technologies. Given the recent booming of the container ecosystem, the container-based virtualization starts receiving more attention for being a promising alternative. Although the container technologies are generally considered to be lightweight, no virtualization solution is ideally resource-free, and the corresponding performance overheads will lead to negative impacts on the quality of Cloud services. To facilitate understanding container technologies from the performance engineering’s perspective, we conducted two-stage performance investigations into Docker containers as a concrete example. At the first stage, we used a physical machine with “just-enough” resource as a baseline to investigate the performance overhead of a standalone Docker container against a standalone virtual machine (VM. With findings contrary to the related work, our evaluation results show that the virtualization’s performance overhead could vary not only on a feature-by-feature basis but also on a job-to-job basis. Moreover, the hypervisor-based technology does not come with higher performance overhead in every case. For example, Docker containers particularly exhibit lower QoS in terms of storage transaction speed. At the ongoing second stage, we employed a physical machine with “fair-enough” resource to implement a container-based MapReduce application and try to optimize its performance. In fact, this machine failed in affording VM-based MapReduce clusters in the same scale. The performance tuning results show that the effects of different optimization strategies could largely be related to the data characteristics. For example, LZO compression can bring the most significant performance improvement when dealing with text data in our case.

  4. Exergy analysis of vapor compression refrigeration cycle with two-stage and intercooler

    Energy Technology Data Exchange (ETDEWEB)

    Kilic, Bayram [Mehmet Akif Ersoy University, Bucak Emin Guelmez Vocational School, Bucak, Burdur (Turkey)

    2012-07-15

    In this study, exergy analyses of vapor compression refrigeration cycle with two-stage and intercooler using refrigerants R507, R407c, R404a were carried out. The necessary thermodynamic values for analyses were calculated by Solkane program. The coefficient of performance, exergetic efficiency and total irreversibility rate of the system in the different operating conditions for these refrigerants were investigated. The coefficient of performance, exergetic efficiency and total irreversibility rate for alternative refrigerants were compared. (orig.)

  5. Two-stage meta-analysis of survival data from individual participants using percentile ratios

    Science.gov (United States)

    Barrett, Jessica K; Farewell, Vern T; Siannis, Fotios; Tierney, Jayne; Higgins, Julian P T

    2012-01-01

    Methods for individual participant data meta-analysis of survival outcomes commonly focus on the hazard ratio as a measure of treatment effect. Recently, Siannis et al. (2010, Statistics in Medicine 29:3030–3045) proposed the use of percentile ratios as an alternative to hazard ratios. We describe a novel two-stage method for the meta-analysis of percentile ratios that avoids distributional assumptions at the study level. Copyright © 2012 John Wiley & Sons, Ltd. PMID:22825835

  6. A Longitudinal Study of Gender-Related Cognition and Behaviour

    Science.gov (United States)

    Campbell, Anne; Shirley, Louisa; Candy, Julia

    2004-01-01

    Gender schema theory proposes that children's acquisition of gender labels and gender stereotypes informs gender-congruent behaviour. Most previous studies have been cross-sectional and do not address the temporal relationship between knowledge and behaviour. We report the results of a longitudinal study of gender knowledge and sex-typed behaviour…

  7. English as a Foreign Language Spelling Development: A Longitudinal Study

    Science.gov (United States)

    Kahn-Horwitz, Janina; Sparks, Richard L.; Goldstein, Zahava

    2012-01-01

    English as a foreign language (EFL) spelling was examined longitudinally three times (4th, 9th, 12th grades) during 9 years of EFL study among Hebrew first language (L1) students. The study examined the impact of L1 literacy variables including phonemic awareness, word attack, and spelling on EFL spelling and the relationship between EFL literacy…

  8. A Longitudinal Study of School Districts' Sustained Improvement

    Science.gov (United States)

    Sampson, Pauline M.

    2011-01-01

    In this longitudinal study of one region in the state of Texas, there was an examination of district leadership and the sustaining of high student achievement for their districts. The results of this study suggest that sustained improvement of student achievement is very difficult. The districts that had sustained improvement had stable district…

  9. Unemployment and psychological distress among graduates: A longitudinal study

    NARCIS (Netherlands)

    Schaufeli, Wilmar B.; Van Yperen, Nico W.

    1992-01-01

    A longitudinal study which addresses the relationship between unemployment and psychological distress in Dutch technical college graduates is presented. Two samples were studied: sample 1 (N = 635) consisted of students leaving technical college and sample 2 (N = 487) consisted of technical college

  10. A longitudinal study of tooth erosion in adolescents.

    NARCIS (Netherlands)

    El Aidi, H.; Bronkhorst, E.M.; Truin, G.J.

    2008-01-01

    Incidence studies on tooth erosion among adolescents are scarce. This longitudinal study aimed at estimating the prevalence, incidence, progression, and distribution of erosion in young adolescents over a 1.5-year period. Erosion at baseline was present in 32.2% of the 622 children (mean age, 11.9

  11. An adaptive two-stage dose-response design method for establishing proof of concept.

    Science.gov (United States)

    Franchetti, Yoko; Anderson, Stewart J; Sampson, Allan R

    2013-01-01

    We propose an adaptive two-stage dose-response design where a prespecified adaptation rule is used to add and/or drop treatment arms between the stages. We extend the multiple comparison procedures-modeling (MCP-Mod) approach into a two-stage design. In each stage, we use the same set of candidate dose-response models and test for a dose-response relationship or proof of concept (PoC) via model-associated statistics. The stage-wise test results are then combined to establish "global" PoC using a conditional error function. Our simulation studies showed good and more robust power in our design method compared to conventional and fixed designs.

  12. Sample size reassessment for a two-stage design controlling the false discovery rate.

    Science.gov (United States)

    Zehetmayer, Sonja; Graf, Alexandra C; Posch, Martin

    2015-11-01

    Sample size calculations for gene expression microarray and NGS-RNA-Seq experiments are challenging because the overall power depends on unknown quantities as the proportion of true null hypotheses and the distribution of the effect sizes under the alternative. We propose a two-stage design with an adaptive interim analysis where these quantities are estimated from the interim data. The second stage sample size is chosen based on these estimates to achieve a specific overall power. The proposed procedure controls the power in all considered scenarios except for very low first stage sample sizes. The false discovery rate (FDR) is controlled despite of the data dependent choice of sample size. The two-stage design can be a useful tool to determine the sample size of high-dimensional studies if in the planning phase there is high uncertainty regarding the expected effect sizes and variability.

  13. Influence of capacity- and time-constrained intermediate storage in two-stage food production systems

    DEFF Research Database (Denmark)

    Akkerman, Renzo; van Donk, Dirk Pieter; Gaalman, Gerard

    2007-01-01

    In food processing, two-stage production systems with a batch processor in the first stage and packaging lines in the second stage are common and mostly separated by capacity- and time-constrained intermediate storage. This combination of constraints is common in practice, but the literature hardly...... of systems like this. Contrary to the common sense in operations management, the LPT rule is able to maximize the total production volume per day. Furthermore, we show that adding one tank has considerable effects. Finally, we conclude that the optimal setup frequency for batches in the first stage...... pays any attention to this. In this paper, we show how various capacity and time constraints influence the performance of a specific two-stage system. We study the effects of several basic scheduling and sequencing rules in the presence of these constraints in order to learn the characteristics...

  14. Two-stage combustion for reducing pollutant emissions from gas turbine combustors

    Science.gov (United States)

    Clayton, R. M.; Lewis, D. H.

    1981-01-01

    Combustion and emission results are presented for a premix combustor fueled with admixtures of JP5 with neat H2 and of JP5 with simulated partial-oxidation product gas. The combustor was operated with inlet-air state conditions typical of cruise power for high performance aviation engines. Ultralow NOx, CO and HC emissions and extended lean burning limits were achieved simultaneously. Laboratory scale studies of the non-catalyzed rich-burning characteristics of several paraffin-series hydrocarbon fuels and of JP5 showed sooting limits at equivalence ratios of about 2.0 and that in order to achieve very rich sootless burning it is necessary to premix the reactants thoroughly and to use high levels of air preheat. The application of two-stage combustion for the reduction of fuel NOx was reviewed. An experimental combustor designed and constructed for two-stage combustion experiments is described.

  15. Longitudinal coupled-bunch instability studies in the PS

    CERN Document Server

    Damerau, H

    2017-01-01

    The main longitudinal limitation for LHC-type beams inthe PS are coupled-bunch instabilities. A dedicated proto-typefeedbacksystemusingaFinemetcavityasalongitudinalkicker has been installed. Extensive tests with beam havebeen performed to explore the intensity reach with this feed-back. The maximum intensity with nominal longitudinalemittance at PS extraction has been measured, as well as theemittance required to keep the beam longitudinally stableat the design intensity for the High-Luminosity LHC (HL-LHC). A higher-harmonic cavity is a complementary op-tion to extend the intensity reach beyond the capabilities ofthe coupled-bunch feedback. Preliminary machine develop-ment (MD) studies operating one20MHzor one40MHzRF system as a higher harmonic at the flat-top indicate thebeneficial effect on longitudinal beam stability

  16. Modeling two-stage bunch compression with wakefields: Macroscopic properties and microbunching instability

    Directory of Open Access Journals (Sweden)

    R. A. Bosch

    2008-09-01

    Full Text Available In a two-stage compression and acceleration system, where each stage compresses a chirped bunch in a magnetic chicane, wakefields affect high-current bunches. The longitudinal wakes affect the macroscopic energy and current profiles of the compressed bunch and cause microbunching at short wavelengths. For macroscopic wavelengths, impedance formulas and tracking simulations show that the wakefields can be dominated by the resistive impedance of coherent edge radiation. For this case, we calculate the minimum initial bunch length that can be compressed without producing an upright tail in phase space and associated current spike. Formulas are also obtained for the jitter in the bunch arrival time downstream of the compressors that results from the bunch-to-bunch variation of current, energy, and chirp. Microbunching may occur at short wavelengths where the longitudinal space-charge wakes dominate or at longer wavelengths dominated by edge radiation. We model this range of wavelengths with frequency-dependent impedance before and after each stage of compression. The growth of current and energy modulations is described by analytic gain formulas that agree with simulations.

  17. Rule-of-thumb adjustment of sample sizes to accommodate dropouts in a two-stage analysis of repeated measurements.

    Science.gov (United States)

    Overall, John E; Tonidandel, Scott; Starbuck, Robert R

    2006-01-01

    Recent contributions to the statistical literature have provided elegant model-based solutions to the problem of estimating sample sizes for testing the significance of differences in mean rates of change across repeated measures in controlled longitudinal studies with differentially correlated error and missing data due to dropouts. However, the mathematical complexity and model specificity of these solutions make them generally inaccessible to most applied researchers who actually design and undertake treatment evaluation research in psychiatry. In contrast, this article relies on a simple two-stage analysis in which dropout-weighted slope coefficients fitted to the available repeated measurements for each subject separately serve as the dependent variable for a familiar ANCOVA test of significance for differences in mean rates of change. This article is about how a sample of size that is estimated or calculated to provide desired power for testing that hypothesis without considering dropouts can be adjusted appropriately to take dropouts into account. Empirical results support the conclusion that, whatever reasonable level of power would be provided by a given sample size in the absence of dropouts, essentially the same power can be realized in the presence of dropouts simply by adding to the original dropout-free sample size the number of subjects who would be expected to drop from a sample of that original size under conditions of the proposed study.

  18. Two-staged management for all types of congenital pouch colon

    Directory of Open Access Journals (Sweden)

    Rajendra K Ghritlaharey

    2013-01-01

    Full Text Available Background: The aim of this study was to review our experience with two-staged management for all types of congenital pouch colon (CPC. Patients and Methods: This retrospective study included CPC cases that were managed with two-staged procedures in the Department of Paediatric Surgery, over a period of 12 years from 1 January 2000 to 31 December 2011. Results: CPC comprised of 13.71% (97 of 707 of all anorectal malformations (ARM and 28.19% (97 of 344 of high ARM. Eleven CPC cases (all males were managed with two-staged procedures. Distribution of cases (Narsimha Rao et al.′s classification into types I, II, III, and IV were 1, 2, 6, and 2, respectively. Initial operative procedures performed were window colostomy (n = 6, colostomy proximal to pouch (n = 4, and ligation of colovesical fistula and end colostomy (n = 1. As definitive procedures, pouch excision with abdomino-perineal pull through (APPT of colon in eight, and pouch excision with APPT of ileum in three were performed. The mean age at the time of definitive procedures was 15.6 months (ranges from 3 to 53 months and the mean weight was 7.5 kg (ranges from 4 to 11 kg. Good fecal continence was observed in six and fair in two cases in follow-up periods, while three of our cases lost to follow up. There was no mortality following definitive procedures amongst above 11 cases. Conclusions: Two-staged procedures for all types of CPC can also be performed safely with good results. The most important fact that the definitive procedure is being done without protective stoma and therefore, it avoids stoma closure, stoma-related complications, related cost of stoma closure and hospital stay.

  19. Two-stage residual inclusion estimation: addressing endogeneity in health econometric modeling.

    Science.gov (United States)

    Terza, Joseph V; Basu, Anirban; Rathouz, Paul J

    2008-05-01

    The paper focuses on two estimation methods that have been widely used to address endogeneity in empirical research in health economics and health services research-two-stage predictor substitution (2SPS) and two-stage residual inclusion (2SRI). 2SPS is the rote extension (to nonlinear models) of the popular linear two-stage least squares estimator. The 2SRI estimator is similar except that in the second-stage regression, the endogenous variables are not replaced by first-stage predictors. Instead, first-stage residuals are included as additional regressors. In a generic parametric framework, we show that 2SRI is consistent and 2SPS is not. Results from a simulation study and an illustrative example also recommend against 2SPS and favor 2SRI. Our findings are important given that there are many prominent examples of the application of inconsistent 2SPS in the recent literature. This study can be used as a guide by future researchers in health economics who are confronted with endogeneity in their empirical work.

  20. Assessing efficiency and effectiveness of Malaysian Islamic banks: A two stage DEA analysis

    Science.gov (United States)

    Kamarudin, Norbaizura; Ismail, Wan Rosmanira; Mohd, Muhammad Azri

    2014-06-01

    Islamic banks in Malaysia are indispensable players in the financial industry with the growing needs for syariah compliance system. In the banking industry, most recent studies concerned only on operational efficiency. However rarely on the operational effectiveness. Since the production process of banking industry can be described as a two-stage process, two-stage Data Envelopment Analysis (DEA) can be applied to measure the bank performance. This study was designed to measure the overall performance in terms of efficiency and effectiveness of Islamic banks in Malaysia using Two-Stage DEA approach. This paper presents analysis of a DEA model which split the efficiency and effectiveness in order to evaluate the performance of ten selected Islamic Banks in Malaysia for the financial year period ended 2011. The analysis shows average efficient score is more than average effectiveness score thus we can say that Malaysian Islamic banks were more efficient rather than effective. Furthermore, none of the bank exhibit best practice in both stages as we can say that a bank with better efficiency does not always mean having better effectiveness at the same time.

  1. Accelerated brain aging in schizophrenia : A longitudinal pattern recognition study

    NARCIS (Netherlands)

    Schnack, Hugo G.; Van Haren, Neeltje E M; Nieuwenhuis, Mireille; Pol, Hilleke E Hulshoff; Cahn, Wiepke; Kahn, René S.

    2016-01-01

    OBJECTIVE: Despite the multitude of longitudinal neuroimaging studies that have been published, a basic question on the progressive brain loss in schizophrenia remains unaddressed: Does it reflect accelerated aging of the brain, or is it caused by a fundamentally different process? The authors used

  2. Accelerated Brain Aging in Schizophrenia : A Longitudinal Pattern Recognition Study

    NARCIS (Netherlands)

    Schnack, Hugo G; van Haren, Neeltje E M; Nieuwenhuis, Mireille; Hulshoff Pol, Hilleke E; Cahn, Wiepke; Kahn, René S

    2016-01-01

    OBJECTIVE: Despite the multitude of longitudinal neuroimaging studies that have been published, a basic question on the progressive brain loss in schizophrenia remains unaddressed: Does it reflect accelerated aging of the brain, or is it caused by a fundamentally different process? The authors used

  3. Stages of Headship: A Longitudinal Study of the Principalship.

    Science.gov (United States)

    Weindling, Dick

    This paper uses socialization theory to re-examine a unique, 10-year longitudinal study of headteachers so as to describe the stages of headship transition. It outlines prior models of leadership succession in both business and schools and produces a stage theory of headship that can be used not only as a research tool, but also as a way to assist…

  4. A Longitudinal Study Assessing the Microsoft Office Skills Course

    Science.gov (United States)

    Carpenter, Donald A.; McGinnis, Denise; Slauson, Gayla Jo; Snyder, Johnny

    2013-01-01

    This paper explains a four-year longitudinal study of the assessment process for a Microsoft Office skills course. It examines whether there is an increase in students' knowledge based on responses to pre- and post-surveys that asked students to evaluate how well they can do particular tasks. Classical classroom teaching methods were used in the…

  5. Criminal Victimization and Crime Risk Perception: A Multilevel Longitudinal Study

    Science.gov (United States)

    Russo, Silvia; Roccato, Michele; Vieno, Alessio

    2013-01-01

    In a national sample of the Italian population, surveyed four times between October 2002 and January 2007 (N = 2,008), we performed a multilevel longitudinal study aimed at predicting the increase in crime risk perception as a function of three families of independent variables, respectively lying at the within individual level (direct…

  6. Experimental study of the longitudinal instability for beam transport

    International Nuclear Information System (INIS)

    Reiser, M.; Wang, J.G.; Guo, W.M.; Wang, D.X.

    1990-01-01

    Theoretical model for beam longitudinal instability in a transport pipe with general wall impedance is considered. The result shows that a capacitive wall tends to stabilize the beam. The experimental study of the instability for a pure resistive-wall is presented, including the design parameters, setup and components for the experiment. 6 refs., 3 figs

  7. Procedural justice and prisoners’ mental health problems: A longitudinal study

    NARCIS (Netherlands)

    Beijersbergen, K.A.; Dirkzwager, A.J.E.; Eichelsheim, V.I.; van der Laan, P.H.; Nieuwbeerta, P.

    2013-01-01

    Background Given the high prevalence of mental health problems among prisoners, knowledge on its determinants is important. Prior cross-sectional studies suggest that procedurally just treatment within prison is a significant predictor; however, longitudinal research is lacking. Aim The aims of this

  8. Monitoring of fetuses with intrauterine growth restriction: a longitudinal study

    NARCIS (Netherlands)

    Hecher, K.; Bilardo, C. M.; Stigter, R. H.; Ville, Y.; Hackelöer, B. J.; Kok, H. J.; Senat, M. V.; Visser, G. H.

    2001-01-01

    To describe the time sequence of changes in fetal monitoring variables in intrauterine growth restriction and to correlate these findings with fetal outcome at delivery. This was a prospective longitudinal observational multicenter study on 110 singleton pregnancies with growth-restricted fetuses

  9. A prospective longitudinal study to estimate the prevalence of ...

    African Journals Online (AJOL)

    A prospective longitudinal study to estimate the prevalence of obesity in Egyptian children with nocturnal enuresis and the association between body mass index and ... Egyptian Journal of Medical Human Genetics ... Response to the treatment was evaluated statistically and correlated with body mass index percentile.

  10. Secondary Analysis of National Longitudinal Transition Study 2 Data

    Science.gov (United States)

    Hicks, Tyler A.; Knollman, Greg A.

    2015-01-01

    This review examines published secondary analyses of National Longitudinal Transition Study 2 (NLTS2) data, with a primary focus upon statistical objectives, paradigms, inferences, and methods. Its primary purpose was to determine which statistical techniques have been common in secondary analyses of NLTS2 data. The review begins with an…

  11. Always connected: a longitudinal field study of mobile communication

    NARCIS (Netherlands)

    Peters, O.; Ben Allouch, Soumaya

    2005-01-01

    Twenty-five novice users of a new mobile communication device were closely tracked for a period of three months. The results of this longitudinal field study show that people’s motivations for using mobile communication technology are initially influenced more strongly by their perceptions about the

  12. Potential Reciprocal Relationship between Motivation and Achievement: A Longitudinal Study

    Science.gov (United States)

    Liu, Yuan; Hou, Shumeng

    2018-01-01

    Among the non-cognitive factors that influence academic achievement, intrinsic motivation has been found to be a potential reciprocal factor. The present study aims to determine the causal relationship between other types of motivation and academic achievement. For this purpose, a large-scale data survey, the National Education Longitudinal Study…

  13. A Longitudinal Study of the Impact of an Environmental Action

    Science.gov (United States)

    Rioux, Liliane; Pasquier, Daniel

    2013-01-01

    In a previous study, we investigated the impact of an awareness-raising campaign on the behaviour of secondary school children in the Centre Region of France, regarding the recycling of used batteries. But, was it a question of pro-environmental behaviour or simply an environmental action? To answer this question, a three-year longitudinal study…

  14. Minor Delinquency and Immigration: A Longitudinal Study among Male Adolescents

    Science.gov (United States)

    Titzmann, Peter F.; Silbereisen, Rainer K.; Mesch, Gustavo

    2014-01-01

    On the basis of general theories of delinquency and the specific situation of immigrants, this longitudinal study investigated predictors of initial levels and rates of change in delinquency among 188 male ethnic German Diaspora immigrants from the former Soviet Union (FSU) in Germany, 237 male native German adolescents, and 182 male Jewish…

  15. Longitudinal Study on Reciprocity between Personality Traits and Parenting Stress

    Science.gov (United States)

    Rantanen, Johanna; Tillemann, Kati; Metsäpelto, Riitta-Leena; Kokko, Katja; Pulkkinen, Lea

    2015-01-01

    Reciprocal associations between the Big Five personality traits and parenting stress--including both parents' feelings of their distress and perception of their incompetence as parents--were studied with 248 participants (49% of which were males). Longitudinal data, collected at ages 33/36, 42 and 50 years, were used. Cross-lagged path analysis…

  16. A Longitudinal Study on Learner Career Advancement in MOOCs

    Science.gov (United States)

    Wang, Yuan; Paquette, Luc; Baker, Ryan

    2014-01-01

    In this paper, we present progress towards a longitudinal study of the post-course career advancement of MOOC learners. We present initial results and analysis plans for how to link this to in-course behaviour, towards better understanding the goals of all MOOC learners.

  17. A Longitudinal Study of Consumer Socialization.

    Science.gov (United States)

    Moschis, George P.; Moore, Roy L.

    A study examined the effects of factors (including television, family, peers, age, and socioeconomic status) on consumer socialization, the process by which individuals develop consumption-related cognitions and behaviors. The specific criterion variables studied included consumer affairs knowledge, puffery filtering, consumer finance management,…

  18. Two-stage hepatectomy: who will not jump over the second hurdle?

    Science.gov (United States)

    Turrini, O; Ewald, J; Viret, F; Sarran, A; Goncalves, A; Delpero, J-R

    2012-03-01

    Two-stage hepatectomy uses compensatory liver regeneration after a first noncurative hepatectomy to enable a second curative resection in patients with bilobar colorectal liver metastasis (CLM). To determine the predictive factors of failure of two-stage hepatectomy. Between 2000 and 2010, 48 patients with irresectable CLM were eligible for two-stage hepatectomy. The planned strategy was a) cleaning of the left hepatic lobe (first hepatectomy), b) right portal vein embolisation and c) right hepatectomy (second hepatectomy). Six patients had occult CLM (n = 5) or extra-hepatic disease (n = 1), which was discovered during the first hepatectomy. Thus, 42 patients completed the first hepatectomy and underwent portal vein embolisation in order to receive the second hepatectomy. Eight patients did not undergo a second hepatectomy due to disease progression. Upon univariate analysis, two factors were identified that precluded patients from having the second hepatectomy: the combined resection of a primary tumour during the first hepatectomy (p = 0.01) and administration of chemotherapy between the two hepatectomies (p = 0.03). An independent association with impairment to perform the two-stage strategy was demonstrated by multivariate analysis for only the combined resection of the primary colorectal cancer during the first hepatectomy (p = 0.04). Due to the small number of patients and the absence of equivalent conclusions in other studies, we cannot recommend performance of an isolated colorectal resection prior to chemotherapy. However, resection of an asymptomatic primary tumour before chemotherapy should not be considered as an outdated procedure. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Application of two-stage biofilter system for the removal of odorous compounds.

    Science.gov (United States)

    Jeong, Gwi-Taek; Park, Don-Hee; Lee, Gwang-Yeon; Cha, Jin-Myeong

    2006-01-01

    Biofiltration is a biological process which is considered to be one of the more successful examples of biotechnological applications to environmental engineering, and is most commonly used in the removal of odoriferous compounds. In this study, we have attempted to assess the efficiency with which both single and complex odoriferous compounds could be removed, using one- or two-stage biofiltration systems. The tested single odor gases, limonene, alpha-pinene, and iso-butyl alcohol, were separately evaluated in the biofilters. Both limonene and alpha-pinene were removed by 90% or more EC (elimination capacity), 364 g/m3/h and 321 g/m3/h, respectively, at an input concentration of 50 ppm and a retention time of 30 s. The iso-butyl alcohol was maintained with an effective removal yield of more than 90% (EC 375 g/m3/h) at an input concentration of 100 ppm. The complex gas removal scheme was applied with a 200 ppm inlet concentration of ethanol, 70 ppm of acetaldehyde, and 70 ppm of toluene with residence time of 45 s in a one- or two-stage biofiltration system. The removal yield of toluene was determined to be lower than that of the other gases in the one-stage biofilter. Otherwise, the complex gases were sufficiently eliminated by the two-stage biofiltration system.

  20. Effects of earthworm casts and zeolite on the two-stage composting of green waste

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lu, E-mail: zhanglu1211@gmail.com; Sun, Xiangyang, E-mail: xysunbjfu@gmail.com

    2015-05-15

    Highlights: • Earthworm casts (EWCs) and clinoptilolite (CL) were used in green waste composting. • Addition of EWCs + CL improved physico-chemical and microbiological properties. • Addition of EWCs + CL extended the duration of thermophilic periods during composting. • Addition of EWCs + CL enhanced humification, cellulose degradation, and nutrients. • Combined addition of 0.30% EWCs + 25% CL reduced composting time to 21 days. - Abstract: Because it helps protect the environment and encourages economic development, composting has become a viable method for organic waste disposal. The objective of this study was to investigate the effects of earthworm casts (EWCs) (at 0.0%, 0.30%, and 0.60%) and zeolite (clinoptilolite, CL) (at 0%, 15%, and 25%) on the two-stage composting of green waste. The combination of EWCs and CL improved the conditions of the composting process and the quality of the compost products in terms of the thermophilic phase, humification, nitrification, microbial numbers and enzyme activities, the degradation of cellulose and hemicellulose, and physico-chemical characteristics and nutrient contents of final composts. The compost matured in only 21 days with the optimized two-stage composting method rather than in the 90–270 days required for traditional composting. The optimal two-stage composting and the best quality compost were obtained with 0.30% EWCs and 25% CL.

  1. Effects of earthworm casts and zeolite on the two-stage composting of green waste

    International Nuclear Information System (INIS)

    Zhang, Lu; Sun, Xiangyang

    2015-01-01

    Highlights: • Earthworm casts (EWCs) and clinoptilolite (CL) were used in green waste composting. • Addition of EWCs + CL improved physico-chemical and microbiological properties. • Addition of EWCs + CL extended the duration of thermophilic periods during composting. • Addition of EWCs + CL enhanced humification, cellulose degradation, and nutrients. • Combined addition of 0.30% EWCs + 25% CL reduced composting time to 21 days. - Abstract: Because it helps protect the environment and encourages economic development, composting has become a viable method for organic waste disposal. The objective of this study was to investigate the effects of earthworm casts (EWCs) (at 0.0%, 0.30%, and 0.60%) and zeolite (clinoptilolite, CL) (at 0%, 15%, and 25%) on the two-stage composting of green waste. The combination of EWCs and CL improved the conditions of the composting process and the quality of the compost products in terms of the thermophilic phase, humification, nitrification, microbial numbers and enzyme activities, the degradation of cellulose and hemicellulose, and physico-chemical characteristics and nutrient contents of final composts. The compost matured in only 21 days with the optimized two-stage composting method rather than in the 90–270 days required for traditional composting. The optimal two-stage composting and the best quality compost were obtained with 0.30% EWCs and 25% CL

  2. Is the continuous two-stage anaerobic digestion process well suited for all substrates?

    Science.gov (United States)

    Lindner, Jonas; Zielonka, Simon; Oechsner, Hans; Lemmer, Andreas

    2016-01-01

    Two-stage anaerobic digestion systems are often considered to be advantageous compared to one-stage processes. Although process conditions and fermenter setups are well examined, overall substrate degradation in these systems is controversially discussed. Therefore, the aim of this study was to investigate how substrates with different fibre and sugar contents (hay/straw, maize silage, sugar beet) influence the degradation rate and methane production. Intermediates and gas compositions, as well as methane yields and VS-degradation degrees were recorded. The sugar beet substrate lead to a higher pH-value drop 5.67 in the acidification reactor, which resulted in a six time higher hydrogen production in comparison to the hay/straw substrate (pH-value drop 5.34). As the achieved yields in the two-stage system showed a difference of 70.6% for the hay/straw substrate, and only 7.8% for the sugar beet substrate. Therefore two-stage systems seem to be only recommendable for digesting sugar rich substrates. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Longitudinal MRI studies of brain morphometry

    DEFF Research Database (Denmark)

    Skimminge, Arnold Jesper Møller

    High resolution MR images acquired at multiple time points of the brain allow quantification of localized changes induced by external factors such as maturation, ageing or disease progression/recovery. High-dimensional warping of such MR images incorporates changes induced by external factors...... into the accompanying deformation field. Deformation fields from high dimensional warping founds tensor based morphometry (TBM), and provides unique opportunities to study human brain morphology and plasticity. In this thesis, specially adapted image processing streams utilizing several image registration techniques...... to characterize differences between brains, demonstrate the versatility and specificity of the employed voxel-wise morphometric methods. More specifically TBM is used to study neurodegenerative changes following severe traumatic brain injuries. Such injuries progress for months, perhaps even years postinjury...

  4. Personality, Schizophrenia, and Violence: A Longitudinal Study.

    Science.gov (United States)

    Candini, Valentina; Ghisi, Marta; Bottesi, Gioia; Ferrari, Clarissa; Bulgari, Viola; Iozzino, Laura; Boero, Maria Elena; De Francesco, Alessandra; Maggi, Paolo; Segalini, Beatrice; Zuccalli, Vanessa; Giobbio, Gian Marco; Rossi, Giuseppe; de Girolamo, Giovanni

    2017-07-31

    The aims of this study were (a) to investigate the presence of clinically significant personality traits and personality disorders (PD) in patients living in residential facilities, with or without a history of violence (69 and 46, respectively); and (b) to investigate any associations between clinically significant personality traits and PDs, aggression, impulsivity, hostility, and violent behavior during a 1-year follow-up. The most frequent primary diagnoses were schizophrenia (58.3%) and PD (20.9%). Those with a history of violence demonstrated more antisocial and alcohol dependence features and lower depressive PD symptoms than the control group. Hostility levels, antisocial symptoms, and drug dependence, as well as a Structured Clinical Interview for DSM-IV Axis II diagnosis of PD, predicted aggressive and violent behavior during follow-up. The study confirms the relevance of assessing PDs both to evaluate the risk of violent behavior and to plan appropriate preventive and treatment intervention.

  5. Benchmarking energy performance of residential buildings using two-stage multifactor data envelopment analysis with degree-day based simple-normalization approach

    International Nuclear Information System (INIS)

    Wang, Endong; Shen, Zhigang; Alp, Neslihan; Barry, Nate

    2015-01-01

    Highlights: • Two-stage DEA model is developed to benchmark building energy efficiency. • Degree-day based simple normalization is used to neutralize the climatic noise. • Results of a real case study validated the benefits of this new model. - Abstract: Being able to identify detailed meta factors of energy performance is essential for creating effective residential energy-retrofitting strategies. Compared to other benchmarking methods, nonparametric multifactor DEA (data envelopment analysis) is capable of discriminating scale factors from management factors to reveal more details to better guide retrofitting practices. A two-stage DEA energy benchmarking method is proposed in this paper. This method includes (1) first-stage meta DEA which integrates the common degree day metrics for neutralizing noise energy effects of exogenous climatic variables; and (2) second-stage Tobit regression for further detailed efficiency analysis. A case study involving 3-year longitudinal panel data of 189 residential buildings indicated the proposed method has advantages over existing methods in terms of its efficiency in data processing and results interpretation. The results of the case study also demonstrated high consistency with existing linear regression based DEA.

  6. Accounting for dropout reason in longitudinal studies with nonignorable dropout.

    Science.gov (United States)

    Moore, Camille M; MaWhinney, Samantha; Forster, Jeri E; Carlson, Nichole E; Allshouse, Amanda; Wang, Xinshuo; Routy, Jean-Pierre; Conway, Brian; Connick, Elizabeth

    2017-08-01

    Dropout is a common problem in longitudinal cohort studies and clinical trials, often raising concerns of nonignorable dropout. Selection, frailty, and mixture models have been proposed to account for potentially nonignorable missingness by relating the longitudinal outcome to time of dropout. In addition, many longitudinal studies encounter multiple types of missing data or reasons for dropout, such as loss to follow-up, disease progression, treatment modifications and death. When clinically distinct dropout reasons are present, it may be preferable to control for both dropout reason and time to gain additional clinical insights. This may be especially interesting when the dropout reason and dropout times differ by the primary exposure variable. We extend a semi-parametric varying-coefficient method for nonignorable dropout to accommodate dropout reason. We apply our method to untreated HIV-infected subjects recruited to the Acute Infection and Early Disease Research Program HIV cohort and compare longitudinal CD4 + T cell count in injection drug users to nonusers with two dropout reasons: anti-retroviral treatment initiation and loss to follow-up.

  7. Neuropathologic Studies of the Baltimore Longitudinal Study of Aging (BLSA)

    Science.gov (United States)

    O’Brien, Richard J.; Resnick, Susan M.; Zonderman, Alan B.; Ferrucci, Luigi; Crain, Barbara J.; Pletnikova, Olga; Rudow, Gay; Iacono, Diego; Riudavets, Miguel A.; Driscoll, Ira; Price, Donald L.; Martin, Lee J.; Troncoso, Juan C.

    2010-01-01

    The Baltimore Longitudinal Study of Aging (BLSA) was established in 1958 and is one the oldest prospective studies of aging in the USA and the world. The BLSA is supported by the National Institute of Aging (NIA) and its mission is to learn what happens to people as they get old and how to sort out changes due to aging and from those due to disease or other causes. In 1986, an autopsy program combined with comprehensive neurologic and cognitive evaluations was established in collaboration with the Johns Hopkins University Alzheimer’s Disease Research Center (ADRC). Since then, 211 subjects have undergone autopsy. Here we review the key clinical neuropathological correlations from this autopsy series. The focus is on the morphological and biochemical changes that occur in normal aging, and the early neuropathological changes of neurodegenerative diseases, especially Alzheimer’s disease (AD). We highlight the combined clinical, pathologic, morphometric, and biochemical evidence of asymptomatic AD, a state characterized by normal clinical evaluations in subjects with abundant AD pathology. We conclude that in some individuals, successful cognitive aging results from compensatory mechanisms that occur at the neuronal level (i.e., neuronal hypertrophy and synaptic plasticity) whereas a failure of compensation may culminate in disease. PMID:19661626

  8. The Two-stage Constrained Equal Awards and Losses Rules for Multi-Issue Allocation Situation

    NARCIS (Netherlands)

    Lorenzo-Freire, S.; Casas-Mendez, B.; Hendrickx, R.L.P.

    2005-01-01

    This paper considers two-stage solutions for multi-issue allocation situations.Characterisations are provided for the two-stage constrained equal awards and constrained equal losses rules, based on the properties of composition and path independence.

  9. Plasma HVA in psychiatric patients: longitudinal studies.

    Science.gov (United States)

    Javaid, J I; Sharma, R P; Janicak, P G; Davis, J M

    1990-01-01

    Plasma homovanillic acid (pHVA) was measured in 40 inpatients (25 schizophrenic and 15 nonschizophrenic patients) who underwent up to 3 weeks of drug washout. Schizophrenic patients were then treated with trifluoperazine for 4 weeks, and weekly behavioral and pHVA measures were obtained. The baseline pHVA had no relationship to age, sex, washout period, diagnosis, or behavioral rating scores. In schizophrenic patients, the baseline pHVA did not differ significantly from any value obtained during 4 weeks of treatment. Although there was significant improvement in clinical symptoms, this was not related to changes in pHVA. Further, changes in any of the four Brief Psychiatric Rating Scale (BPRS) factors (i.e., positive symptoms, negative symptoms, hostility/suspicion, or anxiety/depression) were not correlated with changes in pHVA. Although other studies have reported a positive correlation between pHVA and psychotic symptoms, results of this study suggest that any observed relationship between pHVA and psychosis must be carefully interpreted.

  10. Two-stage distraction lengthening of the forearm.

    Science.gov (United States)

    Taghinia, Amir H; Al-Sheikh, Ayman A; Panossian, Andre E; Upton, Joseph

    2013-01-01

    Single-stage lengthening of the forearm using callus distraction is well described; however, forearm lengthening using a 2-stage technique of distraction followed by bone grafting has received less attention. A 2-staged technique can be a better alternative in cases where the surgeon desires extensive lengthening. A retrospective review was undertaken of eleven 2-stage forearm lengthening procedures performed by 1 surgeon over a 15-year period. Indications were radial longitudinal deficiency (8 patients), neonatal ischemic contractures (2 patients), and septic growth arrest (1 patient). Average follow-up was 2.8 years. Distraction was performed on patients an average of 82 mm over an average duration of 24 weeks. Average time to union from the time of distractor removal and grafting was 87 days. Average healing index was 32.1 d/cm. Distraction problems were common and related to the length of time that the distractor was in place; they included pain, pin-related infections, and multiple mechanical device difficulties. Three patients had nonunion, and another had delayed union; however, additional procedures resulted in ultimate bony union in all patients. Demineralized bone matrix and autologous corticocancellous bone grafts yielded predictable healing and good functional results in short-distance distractions. For longer distractions, free vascularized fibula transfer produced the best outcomes. Intercalary cortical allografts did not heal well. Patients with neonatal Volkmann contractures had the most difficulty with distraction and healing, ultimately obtaining little to no lengthening and poor functional outcomes.

  11. Shapes related to longitudinal studies of disease

    DEFF Research Database (Denmark)

    Erleben, Lene Lillemark

    investigated four different proximity markers which lead to significantly improved marker values between NC and AD after correction for whole brain and hippocampus volume. Based on the different proximity markers we have chosen the surface connectivity marker that gave the best separation to investigate......This dissertation investigates novel markers for cardiovascular diseases (CVD) and Alzheimer's disease (AD). Both CVD and AD are among the large diseases counted in morbidity and mortality in the western world, which makes them huge and increasing problems. By investigating and learning....... The first part of this dissertation studies the growth patterns of atherosclerotic calcified deposits in the lumbar aorta based on x-ray images over an 8-year time period. We have been able to find simple growth patterns that explain how the calcifications evolve. The calcifications grew on average 41 % (p...

  12. Two-stage revision of septic knee prosthesis with articulating knee spacers yields better infection eradication rate than one-stage or two-stage revision with static spacers.

    Science.gov (United States)

    Romanò, C L; Gala, L; Logoluso, N; Romanò, D; Drago, L

    2012-12-01

    The best method for treating chronic periprosthetic knee infection remains controversial. Randomized, comparative studies on treatment modalities are lacking. This systematic review of the literature compares the infection eradication rate after two-stage versus one-stage revision and static versus articulating spacers in two-stage procedures. We reviewed full-text papers and those with an abstract in English published from 1966 through 2011 that reported the success rate of infection eradication after one-stage or two-stage revision with two different types of spacers. In all, 6 original articles reporting the results after one-stage knee exchange arthoplasty (n = 204) and 38 papers reporting on two-stage revision (n = 1,421) were reviewed. The average success rate in the eradication of infection was 89.8% after a two-stage revision and 81.9% after a one-stage procedure at a mean follow-up of 44.7 and 40.7 months, respectively. The average infection eradication rate after a two-stage procedure was slightly, although significantly, higher when an articulating spacer rather than a static spacer was used (91.2 versus 87%). The methodological limitations of this study and the heterogeneous material in the studies reviewed notwithstanding, this systematic review shows that, on average, a two-stage procedure is associated with a higher rate of eradication of infection than one-stage revision for septic knee prosthesis and that articulating spacers are associated with a lower recurrence of infection than static spacers at a comparable mean duration of follow-up. IV.

  13. Considerations Regarding Age at Surgery and Fistula Incidence Using One- and Two-stage Closure for Cleft Palate

    Directory of Open Access Journals (Sweden)

    Simona Stoicescu

    2013-12-01

    Full Text Available Introduction: Although cleft lip and palate (CLP is one of the most common congenital malformations, occurring in 1 in 700 live births, there is still no generally accepted treatment protocol. Numerous surgical techniques have been described for cleft palate repair; these techniques can be divided into one-stage (one operation cleft palate repair and two-stage cleft palate closure. The aim of this study is to present our cleft palate team experience in using the two-stage cleft palate closure and the clinical outcomes in terms of oronasal fistula rate. Material and methods: A retrospective analysis was performed on medical records of 80 patients who underwent palate repair over a five-year period, from 2008 to 2012. All cleft palate patients were incorporated. Information on patient’s gender, cleft type, age at repair, one- or two-stage cleft palate repair were collected and analyzed. Results: Fifty-three (66% and twenty-seven (34% patients underwent two-stage and one-stage repair, respectively. According to Veau classification, more than 60% of them were Veau III and IV, associating cleft lip to cleft palate. Fistula occurred in 34% of the two-stage repairs versus 7% of one-stage repairs, with an overall incidence of 24%. Conclusions: Our study has shown that a two-stage cleft palate closure has a higher rate of fistula formation when compared with the one-stage repair. Two-stage repair is the protocol of choice in wide complete cleft lip and palate cases, while one-stage procedure is a good option for cleft palate alone, or some specific cleft lip and palate cases (narrow cleft palate, older age at surgery

  14. Predictors of workplace violence among ambulance personnel: a longitudinal study

    OpenAIRE

    van der Velden, Peter G.; Bosmans, Mark W.G.; van der Meulen, Erik

    2015-01-01

    Abstract Aim To examine predictors of repeated confrontations with workplace violence among ambulance personnel, the proportion of exposure to potentially traumatic events that are aggression-related and to what extent personnel was able to prevent escalations. Although previous research assessed the prevalences among this group, little is known about predictors, to what extent PTE’s are WPV-related and their abilities to prevent escalations. Design A longitudinal study with a 6 months’ time ...

  15. Weaving leadership longitudinally: a qualitative study on faculty development

    OpenAIRE

    Joyce, Pauline

    2015-01-01

    Purpose The purpose of this study was to explore if faculty who undertake teacher preparation, which has a leadership intervention across each module, are better prepared to take on educational leadership roles. Methods A cross sectional qualitative approach was used as part of a longitudinal evaluation of a program. The aim was to explore the perceptions of a purposive sample across three cohorts of students. Data was collected via semi-structured interviews and were analyzed by thema...

  16. Longitudinal study on reciprocity between personality traits and parenting stress

    OpenAIRE

    Rantanen, Johanna; Tillemann, Kati; Metsäpelto, Riitta-Leena; Kokko, Katja; Pulkkinen, Lea

    2014-01-01

    Reciprocal associations between the Big Five personality traits and parenting stress—including both parents’ feelings of their distress and perception of their incompetence as parents—were studied with 248 participants (49% of which were males). Longitudinal data, collected at ages 33/36, 42 and 50 years, were used. Cross-lagged path analysis revealed that in case of both mothers and fathers, neuroticism at age 33 predicted high parenting stress, and extraversion at age 33 predicted low paren...

  17. Longitudinal tracking studies for a high intensity proton synchrotron

    International Nuclear Information System (INIS)

    Lessner, E.; Cho, Y.; Harkay, K.; Symon, K.

    1995-01-01

    Results from longitudinal tracking studies for a high intensity proton synchrotron designed for a 1-MW spallation source are presented. The machine delivers a proton beam of 0.5 mA time-averaged current at a repetition rate of 30 Hz. The accelerator is designed to have radiation levels that allow hands-on-maintenance. However, the high beam intensity causes strong space charge fields whose effects may lead to particle loss and longitudinal instabilities. The space charge fields modify the particle distribution, distort the stable bucket area and reduce the rf linear restoring force. Tracking simulations were conducted to analyze the space charge effects on the dynamics of the injection and acceleration processes and means to circumvent them. The tracking studies led to the establishment of the injected beam parameters and rf voltage program that minimized beam loss and longitudinal instabilities. Similar studies for a 10-GeV synchrotron that uses the 2-GeV synchrotron as its injector are also discussed

  18. The global stability of a delayed predator-prey system with two stage-structure

    International Nuclear Information System (INIS)

    Wang Fengyan; Pang Guoping

    2009-01-01

    Based on the classical delayed stage-structured model and Lotka-Volterra predator-prey model, we introduce and study a delayed predator-prey system, where prey and predator have two stages, an immature stage and a mature stage. The time delays are the time lengths between the immature's birth and maturity of prey and predator species. Results on global asymptotic stability of nonnegative equilibria of the delay system are given, which generalize and suggest that good continuity exists between the predator-prey system and its corresponding stage-structured system.

  19. Modelling of Two-Stage Methane Digestion With Pretreatment of Biomass

    Science.gov (United States)

    Dychko, A.; Remez, N.; Opolinskyi, I.; Kraychuk, S.; Ostapchuk, N.; Yevtieieva, L.

    2018-04-01

    Systems of anaerobic digestion should be used for processing of organic waste. Managing the process of anaerobic recycling of organic waste requires reliable predicting of biogas production. Development of mathematical model of process of organic waste digestion allows determining the rate of biogas output at the two-stage process of anaerobic digestion considering the first stage. Verification of Konto's model, based on the studied anaerobic processing of organic waste, is implemented. The dependencies of biogas output and its rate from time are set and may be used to predict the process of anaerobic processing of organic waste.

  20. An Investigation on the Formation of Carbon Nanotubes by Two-Stage Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    M. S. Shamsudin

    2012-01-01

    Full Text Available High density of carbon nanotubes (CNTs has been synthesized from agricultural hydrocarbon: camphor oil using a one-hour synthesis time and a titanium dioxide sol gel catalyst. The pyrolysis temperature is studied in the range of 700–900°C at increments of 50°C. The synthesis process is done using a custom-made two-stage catalytic chemical vapor deposition apparatus. The CNT characteristics are investigated by field emission scanning electron microscopy and micro-Raman spectroscopy. The experimental results showed that structural properties of CNT are highly dependent on pyrolysis temperature changes.

  1. A Novel Two-Stage Dynamic Spectrum Sharing Scheme in Cognitive Radio Networks

    Institute of Scientific and Technical Information of China (English)

    Guodong Zhang; Wei Heng; Tian Liang; Chao Meng; Jinming Hu

    2016-01-01

    In order to enhance the efficiency of spectrum utilization and reduce communication overhead in spectrum sharing process,we propose a two-stage dynamic spectrum sharing scheme in which cooperative and noncooperative modes are analyzed in both stages.In particular,the existence and the uniqueness of Nash Equilibrium (NE) strategies for noncooperative mode are proved.In addition,a distributed iterative algorithm is proposed to obtain the optimal solutions of the scheme.Simulation studies are carried out to show the performance comparison between two modes as well as the system revenue improvement of the proposed scheme compared with a conventional scheme without a virtual price control factor.

  2. Maximally efficient two-stage screening: Determining intellectual disability in Taiwanese military conscripts

    OpenAIRE

    Chien, Chia-Chang; Huang, Shu-Fen; Lung, For-Wey

    2009-01-01

    Chia-Chang Chien1, Shu-Fen Huang1,2,3,4, For-Wey Lung1,2,3,41Department of Psychiatry, Kaohsiung Armed Forces General Hospital, Kaohsiung, Taiwan; 2Graduate Institute of Behavioral Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan; 3Department of Psychiatry, National Defense Medical Center, Taipei, Taiwan; 4Calo Psychiatric Center, Pingtung County, TaiwanObjective: The purpose of this study was to apply a two-stage screening method for the large-scale intelligence screening of militar...

  3. Residents' perceptions of an integrated longitudinal curriculum: a qualitative study.

    Science.gov (United States)

    Lubitz, Rebecca; Lee, Joseph; Hillier, Loretta M

    2015-01-01

    The purpose of this study was to explore family medicine residents' perceptions of a newly restructured integrated longitudinal curriculum. A purposeful sample of 16 family medicine residents participated in focus group interviews conducted from a grounded theory perspective to identify the characteristics of this training model that contribute to and that challenge learning. Eight key themes were identified: continuity of care, relevance to family medicine, autonomy, program-focused preparation, professional development as facilitated by role modeling, patient volume, clarity of expectations for learners, and logistics. Positive learning experiences were marked by high levels of autonomy, continuity, and relevance to family medicine. Less favorable learning experiences were characterized by limited opportunities for continuity of care, limited relevance to family medicine practice and unclear expectations for the resident's role. Family physician-led learning experiences contributed to residents' understanding of the full scope of family medicine practice, more so than specialist-led experiences. The logistics of implementing the integrated block were challenging and negatively impacted continuity and learning. This study suggests that an integrated longitudinalized family medicine block training model has the potential to support the principles of a longitudinal integrated competency-based curriculum to effectively prepare residents for family medicine practice.

  4. A preventive maintenance policy based on dependent two-stage deterioration and external shocks

    International Nuclear Information System (INIS)

    Yang, Li; Ma, Xiaobing; Peng, Rui; Zhai, Qingqing; Zhao, Yu

    2017-01-01

    This paper proposes a preventive maintenance policy for a single-unit system whose failure has two competing and dependent causes, i.e., internal deterioration and sudden shocks. The internal failure process is divided into two stages, i.e. normal and defective. Shocks arrive according to a non-homogeneous Poisson process (NHPP), leading to the failure of the system immediately. The occurrence rate of a shock is affected by the state of the system. Both an age-based replacement and finite number of periodic inspections are schemed simultaneously to deal with the competing failures. The objective of this study is to determine the optimal preventive replacement interval, inspection interval and number of inspections such that the expected cost per unit time is minimized. A case study on oil pipeline maintenance is presented to illustrate the maintenance policy. - Highlights: • A maintenance model based on two-stage deterioration and sudden shocks is developed. • The impact of internal system state on external shock process is studied. • A new preventive maintenance strategy combining age-based replacements and periodic inspections is proposed. • Postponed replacement of a defective system is provided by restricting the number of inspections.

  5. Two-stage optimization in a transportation problem

    CSIR Research Space (South Africa)

    Stewart, TJ

    1979-01-01

    Full Text Available A study of the economic distribution of maize throughout South Africa is reported. Although the problem of minimizing total transportation costs in such a situation is a classical one, and its solution is well known, there was in this case a high...

  6. A cause and effect two-stage BSC-DEA method for measuring the relative efficiency of organizations

    Directory of Open Access Journals (Sweden)

    Seyed Esmaeel Najafi

    2011-01-01

    Full Text Available This paper presents an integration of balanced score card (BSE with two-stage data envelopment analysis (DEA. The proposed model of this paper uses different financial and non-financial perspectives to evaluate the performance of decision making units in different BSC stages. At each stage, a two-stage DEA method is implemented to measure the relative efficiency of decision making units and the results are monitored using the cause and effect relationships. An empirical study for a banking sector is also performed using the method developed in this paper and the results are briefly analyzed.

  7. Enhancement of bioenergy production from organic wastes by two-stage anaerobic hydrogen and methane production process

    DEFF Research Database (Denmark)

    Luo, Gang; Xie, Li; Zhou, Qi

    2011-01-01

    The present study investigated a two-stage anaerobic hydrogen and methane process for increasing bioenergy production from organic wastes. A two-stage process with hydraulic retention time (HRT) 3d for hydrogen reactor and 12d for methane reactor, obtained 11% higher energy compared to a single......:12 to 1:14, 6.7%, more energy could be obtained. Microbial community analysis indicated that the dominant bacterial species were different in the hydrogen reactors (Thermoanaerobacterium thermosaccharolyticum-like species) and methane reactors (Clostridium thermocellum-like species). The changes...

  8. Properties of a two stage adiabatic demagnetization refrigerator

    International Nuclear Information System (INIS)

    Fukuda, H; Ueda, S; Arai, R; Numazawa, T; Li, J; Saito, A T; Nakagome, H

    2015-01-01

    Currently, many space missions using cryogenic temperatures are being planned. In particular, high resolution sensors such as Transition Edge Sensors need very low temperatures, below 100 mK. It is well known that the adiabatic demagnetization refrigerator (ADR) is one of most useful tools for producing ultra-low temperatures in space because it is gravity independent. We studied a continuous ADR system consisting of 4 stages and demonstrated it could provide continuous temperatures around 100 mK. However, there was some heat leakage from the power leads which resulted in reduced cooling power. Our efforts to upgrade our ADR system are presented. We show the effect of using the HTS power leads and discuss a cascaded Carnot cycle consisting of 2 ADR units. (paper)

  9. Two-stage model of development of heterogeneous uranium-lead systems in zircon

    International Nuclear Information System (INIS)

    Mel'nikov, N.N.; Zevchenkov, O.A.

    1985-01-01

    Behaviour of isotope systems of multiphase zircons at their two-stage distortion is considered. The results of calculations testify to the fact that linear correlations on the diagram with concordance can be explained including two-stage discovery of U-Pb systems of cogenetic zircons if zircon is considered physically heterogeneous and losing in its different part different ratios of accumulated radiogenic lead. ''Metamorphism ages'' obtained by these two-stage opening zircons are intermediate, and they not have geochronological significance while ''crystallization ages'' remain rather close to real ones. Two-stage opening zircons in some cases can be diagnosed by discordance of their crystal component

  10. A two-stage stochastic programming model for the optimal design of distributed energy systems

    International Nuclear Information System (INIS)

    Zhou, Zhe; Zhang, Jianyun; Liu, Pei; Li, Zheng; Georgiadis, Michael C.; Pistikopoulos, Efstratios N.

    2013-01-01

    Highlights: ► The optimal design of distributed energy systems under uncertainty is studied. ► A stochastic model is developed using genetic algorithm and Monte Carlo method. ► The proposed system possesses inherent robustness under uncertainty. ► The inherent robustness is due to energy storage facilities and grid connection. -- Abstract: A distributed energy system is a multi-input and multi-output energy system with substantial energy, economic and environmental benefits. The optimal design of such a complex system under energy demand and supply uncertainty poses significant challenges in terms of both modelling and corresponding solution strategies. This paper proposes a two-stage stochastic programming model for the optimal design of distributed energy systems. A two-stage decomposition based solution strategy is used to solve the optimization problem with genetic algorithm performing the search on the first stage variables and a Monte Carlo method dealing with uncertainty in the second stage. The model is applied to the planning of a distributed energy system in a hotel. Detailed computational results are presented and compared with those generated by a deterministic model. The impacts of demand and supply uncertainty on the optimal design of distributed energy systems are systematically investigated using proposed modelling framework and solution approach.

  11. Use of a two-stage light-gas gun as an injector for electromagnetic railguns

    International Nuclear Information System (INIS)

    Shahinpoor, M.

    1989-01-01

    Ablation of wall materials is known to be a major factor limiting the performance of railguns. To minimize this effect, it is desirable too inject projectiles into railgun at velocities greater than the ablation threshold velocity (6-8 km/s for copper rails). Because two-stage light-gas guns are capable of achieving such velocities, a program was initiated to design, build and evaluate the performance of a two-stage light gas gun, utilizing hydrogen gas, for use as an injector to an electromagnetic railgun. This effort is part of a project to develop a hypervelocity electromagnetic launcher (HELEOS) for use in equation-of-state studies. In this paper, the specific design features that enhance compatibility of the injector with the railgun, including a slip-joint between the injector launch tube and the coupling section to the railgun are described. The operational capabilities for using all major projectile velocity measuring techniques, such as in-bore pressure gauges, laser and CW x-ray interrupt techniques, flash x-ray and continuous in-bore velocity measurements using VISAR interferometry are also discussed. Finally an internal ballistics code for optimizing gun performance has been utilized to interpret performance data of the gun

  12. Two-stage heterotrophic and phototrophic culture strategy for algal biomass and lipid production.

    Science.gov (United States)

    Zheng, Yubin; Chi, Zhanyou; Lucker, Ben; Chen, Shulin

    2012-01-01

    A two-stage heterotrophic and phototrophic culture strategy for algal biomass and lipid production was studied, wherein high density heterotrophic cultures of Chlorellasorokiniana serve as seed for subsequent phototrophic growth. The data showed growth rate, cell density and productivity of heterotrophic C.sorokiniana were 3.0, 3.3 and 7.4 times higher than phototrophic counterpart, respectively. Hetero- and phototrophic algal seeds had similar biomass/lipid production and fatty acid profile when inoculated into phototrophic culture system. To expand the application, food waste and wastewater were tested as feedstock for heterotrophic growth, and supported cell growth successfully. These results demonstrated the advantages of using heterotrophic algae cells as seeds for open algae culture system. Additionally, high inoculation rate of heterotrophic algal seed can be utilized as an effective method for contamination control. This two-stage heterotrophic phototrophic process is promising to provide a more efficient way for large scale production of algal biomass and biofuels. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Two-stage single-volume exchange transfusion in severe hemolytic disease of the newborn.

    Science.gov (United States)

    Abbas, Wael; Attia, Nayera I; Hassanein, Sahar M A

    2012-07-01

    Evaluation of two-stage single-volume exchange transfusion (TSSV-ET) in decreasing the post-exchange rebound increase in serum bilirubin level, with subsequent reduction of the need for repeated exchange transfusions. The study included 104 neonates with hyperbilirubinemia needing exchange transfusion. They were randomly enrolled into two equal groups, each group comprised 52 neonates. TSSV-ET was performed for the 52 neonates and the traditional single-stage double-volume exchange transfusion (SSDV-ET) was performed to 52 neonates. TSSV-ET significantly lowered rebound serum bilirubin level (12.7 ± 1.1 mg/dL), compared to SSDV-ET (17.3 ± 1.7 mg/dL), p < 0.001. Need for repeated exchange transfusions was significantly lower in TSSV-ET group (13.5%), compared to 32.7% in SSDV-ET group, p < 0.05. No significant difference was found between the two groups as regards the morbidity (11.5% and 9.6%, respectively) and the mortality (1.9% for both groups). Two-stage single-volume exchange transfusion proved to be more effective in reducing rebound serum bilirubin level post-exchange and in decreasing the need for repeated exchange transfusions.

  14. Fate of dissolved organic nitrogen in two stage trickling filter process.

    Science.gov (United States)

    Simsek, Halis; Kasi, Murthy; Wadhawan, Tanush; Bye, Christopher; Blonigen, Mark; Khan, Eakalak

    2012-10-15

    Dissolved organic nitrogen (DON) represents a significant portion of nitrogen in the final effluent of wastewater treatment plants (WWTPs). Biodegradable portion of DON (BDON) can support algal growth and/or consume dissolved oxygen in the receiving waters. The fate of DON and BDON has not been studied for trickling filter WWTPs. DON and BDON data were collected along the treatment train of a WWTP with a two-stage trickling filter process. DON concentrations in the influent and effluent were 27% and 14% of total dissolved nitrogen (TDN). The plant removed about 62% and 72% of the influent DON and BDON mainly by the trickling filters. The final effluent BDON values averaged 1.8 mg/L. BDON was found to be between 51% and 69% of the DON in raw wastewater and after various treatment units. The fate of DON and BDON through the two-stage trickling filter treatment plant was modeled. The BioWin v3.1 model was successfully applied to simulate ammonia, nitrite, nitrate, TDN, DON and BDON concentrations along the treatment train. The maximum growth rates for ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria, and AOB half saturation constant influenced ammonia and nitrate output results. Hydrolysis and ammonification rates influenced all of the nitrogen species in the model output, including BDON. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Optimization of Two-Stage Peltier Modules: Structure and Exergetic Efficiency

    Directory of Open Access Journals (Sweden)

    Cesar Ramirez-Lopez

    2012-08-01

    Full Text Available In this paper we undertake the theoretical analysis of a two-stage semiconductor thermoelectric module (TEM which contains an arbitrary and different number of thermocouples, n1 and n2, in each stage (pyramid-styled TEM. The analysis is based on a dimensionless entropy balance set of equations. We study the effects of n1 and n2, the flowing electric currents through each stage, the applied temperatures and the thermoelectric properties of the semiconductor materials on the exergetic efficiency. Our main result implies that the electric currents flowing in each stage must necessarily be different with a ratio about 4.3 if the best thermal performance and the highest temperature difference possible between the cold and hot side of the device are pursued. This fact had not been pointed out before for pyramid-styled two stage TEM. The ratio n1/n2 should be about 8.

  16. Two-stage stochastic programming model for the regional-scale electricity planning under demand uncertainty

    International Nuclear Information System (INIS)

    Huang, Yun-Hsun; Wu, Jung-Hua; Hsu, Yu-Ju

    2016-01-01

    Traditional electricity supply planning models regard the electricity demand as a deterministic parameter and require the total power output to satisfy the aggregate electricity demand. But in today's world, the electric system planners are facing tremendously complex environments full of uncertainties, where electricity demand is a key source of uncertainty. In addition, electricity demand patterns are considerably different for different regions. This paper developed a multi-region optimization model based on two-stage stochastic programming framework to incorporate the demand uncertainty. Furthermore, the decision tree method and Monte Carlo simulation approach are integrated into the model to simplify electricity demands in the form of nodes and determine the values and probabilities. The proposed model was successfully applied to a real case study (i.e. Taiwan's electricity sector) to show its applicability. Detail simulation results were presented and compared with those generated by a deterministic model. Finally, the long-term electricity development roadmap at a regional level could be provided on the basis of our simulation results. - Highlights: • A multi-region, two-stage stochastic programming model has been developed. • The decision tree and Monte Carlo simulation are integrated into the framework. • Taiwan's electricity sector is used to illustrate the applicability of the model. • The results under deterministic and stochastic cases are shown for comparison. • Optimal portfolios of regional generation technologies can be identified.

  17. A two-stage inexact joint-probabilistic programming method for air quality management under uncertainty.

    Science.gov (United States)

    Lv, Y; Huang, G H; Li, Y P; Yang, Z F; Sun, W

    2011-03-01

    A two-stage inexact joint-probabilistic programming (TIJP) method is developed for planning a regional air quality management system with multiple pollutants and multiple sources. The TIJP method incorporates the techniques of two-stage stochastic programming, joint-probabilistic constraint programming and interval mathematical programming, where uncertainties expressed as probability distributions and interval values can be addressed. Moreover, it can not only examine the risk of violating joint-probability constraints, but also account for economic penalties as corrective measures against any infeasibility. The developed TIJP method is applied to a case study of a regional air pollution control problem, where the air quality index (AQI) is introduced for evaluation of the integrated air quality management system associated with multiple pollutants. The joint-probability exists in the environmental constraints for AQI, such that individual probabilistic constraints for each pollutant can be efficiently incorporated within the TIJP model. The results indicate that useful solutions for air quality management practices have been generated; they can help decision makers to identify desired pollution abatement strategies with minimized system cost and maximized environmental efficiency. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. Risk averse optimal operation of a virtual power plant using two stage stochastic programming

    International Nuclear Information System (INIS)

    Tajeddini, Mohammad Amin; Rahimi-Kian, Ashkan; Soroudi, Alireza

    2014-01-01

    VPP (Virtual Power Plant) is defined as a cluster of energy conversion/storage units which are centrally operated in order to improve the technical and economic performance. This paper addresses the optimal operation of a VPP considering the risk factors affecting its daily operation profits. The optimal operation is modelled in both day ahead and balancing markets as a two-stage stochastic mixed integer linear programming in order to maximize a GenCo (generation companies) expected profit. Furthermore, the CVaR (Conditional Value at Risk) is used as a risk measure technique in order to control the risk of low profit scenarios. The uncertain parameters, including the PV power output, wind power output and day-ahead market prices are modelled through scenarios. The proposed model is successfully applied to a real case study to show its applicability and the results are presented and thoroughly discussed. - Highlights: • Virtual power plant modelling considering a set of energy generating and conversion units. • Uncertainty modelling using two stage stochastic programming technique. • Risk modelling using conditional value at risk. • Flexible operation of renewable energy resources. • Electricity price uncertainty in day ahead energy markets

  19. SCI Longitudinal Aging Study: 40 Years of Research.

    Science.gov (United States)

    Krause, James S; Clark, Jillian M R; Saunders, Lee L

    2015-01-01

    The Spinal Cord Injury (SCI) Longitudinal Aging Study was initiated in 1973 and has conducted 8 assessments over the past 40 years. It was designed to help rehabilitation professionals understand the life situation of people with SCI, but it has developed into the most long-standing study of aging and SCI and has resulted in over 50 publications. Our purpose was to provide a detailed history of the study, response patterns, utilization of measures, and a summary of key findings reported in the literature. Five participant samples have been incorporated over the 40 years, with enrollment in 1973, 1984, 1993 (2 samples), and 2003. A total of 2,208 participants have completed 6,001 assessments, with a particularly large number of assessments among those who are more than 40 years post injury (n = 349). The overall results have indicated changing patterns of outcomes over time as persons with SCI age, with some notable declines in participation and health. There has been a survivor effect whereby persons who are more active, well-adjusted, and healthier live longer. This study has several important features that are required for longitudinal research including (a) consistency of follow-up, (b) consistency of measures over time, (c) addition of new participant samples to counteract attrition, and (d) inclusion of a large number of individuals who have reached aging milestones unparalleled in the literature. Data from this study can inform the literature on the natural course of aging with SCI.

  20. Children in care (CIC): A Danish longitudinal study

    DEFF Research Database (Denmark)

    Egelund, Tine; Hestbæk, Anne-Dorthe

    This paper presents results describing what characterizes young, Danish children in care and their parents, and, furthermore, discusses social policy implications of the complex psychosocial disadvantages influencing the families. The paper is based on a longitudinal study of all Danish children......, born in 1995, who currently are or formerly have been placed in care. The first data collection was conducted in the spring 2003, where the children were 7-8 years of age. It is the intention to follow up the children every third year during childhood, adolescence, and adult life. At each new data...

  1. Leadership in transformation: a longitudinal study in a nursing organization.

    Science.gov (United States)

    Viitala, Riitta

    2014-01-01

    Not only does leadership produce changes, but those changes produce leadership in organisations. The purpose of this paper is to present a theoretical and empirical analysis of the transformation of leadership at two different historical points in a health care organisation. It leans on the perspective of social constructionism, drawing especially from the ideas of Berger and Luckmann (1966). The paper seeks to improve understanding of how leaders themselves construct leadership in relation to organisational change. The empirical material was gathered in a longitudinal case study in a nursing organisation in two different historical and situational points. It consists of written narratives produced by nurse leaders that are analysed by applying discourse analysis. The empirical study revealed that the constructions of leadership were dramatically different at the two different historical and situational points. Leadership showed up as a complex, fragile and changing phenomenon, which fluctuates along with the other organisational changes. The results signal the importance of agency in leadership and the central role of "significant others". The paper questions the traditional categorisation and labelling of leadership as well as the cross-sectional studies in understanding leadership transformation. Its originality relates to the longitudinal perspective on transformation of leadership in the context of a health care organisation.

  2. Two-stage process analysis using the process-based performance measurement framework and business process simulation

    NARCIS (Netherlands)

    Han, K.H.; Kang, J.G.; Song, M.S.

    2009-01-01

    Many enterprises have recently been pursuing process innovation or improvement to attain their performance goals. To align a business process with enterprise performances, this study proposes a two-stage process analysis for process (re)design that combines the process-based performance measurement

  3. External Fixation versus two-stage Open Reduction Internal Fixation of distal intra-articular Tibia fractures; a Systematic Review

    DEFF Research Database (Denmark)

    Ladeby Erichsen, Julie; Jensen, Carsten; Damborg, Frank Lindhøj

    Internal Fixation (ORIF) or External Fixation (EF). Method : A search was conducted using PUBMED, Embase, Cochrane Central, Open Grey, Orthopaedic Proceedings and WHO International Clinical Trials Registry Platform. Studies with level of evidence I-IV comparing EF with two-stage ORIF of DIATF in patients...

  4. A Two-Stage Diagnosis Framework for Wind Turbine Gearbox Condition Monitoring

    Directory of Open Access Journals (Sweden)

    Janet M. Twomey

    2013-01-01

    Full Text Available Advances in high performance sensing technologies enable the development of wind turbine condition monitoring system to diagnose and predict the system-wide effects of failure events. This paper presents a vibration-based two stage fault detection framework for failure diagnosis of rotating components in wind turbines. The proposed framework integrates an analytical defect detection method and a graphical verification method together to ensure the diagnosis efficiency and accuracy. The efficacy of the proposed methodology is demonstrated with a case study with the gearbox condition monitoring Round Robin study dataset provided by the National Renewable Energy Laboratory (NREL. The developed methodology successfully picked five faults out of seven in total with accurate severity levels without producing any false alarm in the blind analysis. The case study results indicated that the developed fault detection framework is effective for analyzing gear and bearing faults in wind turbine drive train system based upon system vibration characteristics.

  5. The Australian longitudinal study on male health-methods

    Directory of Open Access Journals (Sweden)

    Dianne Currier

    2016-10-01

    Full Text Available Abstract Background The Australian Longitudinal Study on Male Health (Ten to Men was established in 2011 to build the evidence base on male health to inform policy and program development. Methods Ten to Men is a national longitudinal study with a stratified multi-stage cluster random sample design and oversampling in rural and regional areas. Household recruitment was conducted from October 2013 to July 2014. Males who were aged 10 to 55 years residing in private dwellings were eligible to participate. Data were collected via self-completion paper questionnaires (participants aged 15 to 55 and by computer-assisted personal interview (boys aged 10 to 14. Household and proxy health data for boys were collected from a parent via a self-completion paper-based questionnaire. Questions covered socio-demographics, health status, mental health and wellbeing, health behaviours, social determinants, and health knowledge and service use. Results A cohort of 15,988 males aged between 10 and 55 years was recruited representing a response fraction of 35 %. Conclusion Ten to Men is a unique resource for investigating male health and wellbeing. Wave 1 data are available for approved research projects.

  6. Association between bacterial vaginosis and partner concurrency: a longitudinal study.

    Science.gov (United States)

    Kenyon, Chris R; Buyze, Jozefien; Klebanoff, Mark; Brotman, Rebecca M

    2018-02-01

    The study aimed to test if there was an association between prevalent bacterial vaginosis (BV) and women reporting that their partner had other partners at the same time (partner concurrency). This association has not been assessed in a longitudinal cohort. The Longitudinal Study of Vaginal Flora recruited a cohort of 3620 non-pregnant women aged 15-44 years who presented for routine primary healthcare at 12 clinics in Birmingham, Alabama. Behavioural questionnaires and vaginal smears were obtained quarterly for a year and BV was defined by a Nugent score 7 or higher as well as Amsel criteria. Mixed effects logistic regression was used to assess the relationship between prevalent BV and reporting that one's partner had other partners in the preceding 3-6 months time interval. Nugent score prevalent BV was associated with both reporting that one's partner definitely (adjusted OR (aOR) 1.5; 95% CI 1.2 to 1.8) and possibly (aOR 1.5; 95% CI 1.2 to 1.8) engaged in partner concurrency in the preceding 3-6 months time period. Prevalent BV diagnosed by Amsel criteria was similar. A diagnosis of prevalent BV was associated with reporting that one's partner possibly or definitely engaged in partner concurrency. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  7. One-stage versus two-stage exchange arthroplasty for infected total knee arthroplasty: a systematic review.

    Science.gov (United States)

    Nagra, Navraj S; Hamilton, Thomas W; Ganatra, Sameer; Murray, David W; Pandit, Hemant

    2016-10-01

    Infection complicating total knee arthroplasty (TKA) has serious implications. Traditionally the debate on whether one- or two-stage exchange arthroplasty is the optimum management of infected TKA has favoured two-stage procedures; however, a paradigm shift in opinion is emerging. This study aimed to establish whether current evidence supports one-stage revision for managing infected TKA based on reinfection rates and functional outcomes post-surgery. MEDLINE/PubMed and CENTRAL databases were reviewed for studies that compared one- and two-stage exchange arthroplasty TKA in more than ten patients with a minimum 2-year follow-up. From an initial sample of 796, five cohort studies with a total of 231 patients (46 single-stage/185 two-stage; median patient age 66 years, range 61-71 years) met inclusion criteria. Overall, there were no significant differences in risk of reinfection following one- or two-stage exchange arthroplasty (OR -0.06, 95 % confidence interval -0.13, 0.01). Subgroup analysis revealed that in studies published since 2000, one-stage procedures have a significantly lower reinfection rate. One study investigated functional outcomes and reported that one-stage surgery was associated with superior functional outcomes. Scarcity of data, inconsistent study designs, surgical technique and antibiotic regime disparities limit recommendations that can be made. Recent studies suggest one-stage exchange arthroplasty may provide superior outcomes, including lower reinfection rates and superior function, in select patients. Clinically, for some patients, one-stage exchange arthroplasty may represent optimum treatment; however, patient selection criteria and key components of surgical and post-operative anti-microbial management remain to be defined. III.

  8. A longitudinal study of memory advantages in bilinguals.

    Directory of Open Access Journals (Sweden)

    Jessica K Ljungberg

    Full Text Available Typically, studies of cognitive advantages in bilinguals have been conducted previously by using executive and inhibitory tasks (e.g. Simon task and applying cross-sectional designs. This study longitudinally investigated bilingual advantages on episodic memory recall, verbal letter and categorical fluency during the trajectory of life. Monolingual and bilingual participants (n=178 between 35-70 years at baseline were drawn from the Betula Prospective Cohort Study of aging, memory, and health. Results showed that bilinguals outperformed monolinguals at the first testing session and across time both in episodic memory recall and in letter fluency. No interaction with age was found indicating that the rate of change across ages was similar for bilinguals and monolinguals. As predicted and in line with studies applying cross-sectional designs, no advantages associated with bilingualism were found in the categorical fluency task. The results are discussed in the light of successful aging.

  9. Postural changes in dental hygienists. Four-year longitudinal study.

    Science.gov (United States)

    Barry, R M; Woodall, W R; Mahan, J M

    1992-01-01

    Numerous surveys identify the occurrence of musculoskeletal complaints as a concern in dentistry. However, no longitudinal data exist to indicate whether postural changes occur as a result of practicing dental hygiene. The purpose of this preliminary, four-year longitudinal study was to investigate whether any postural changes developed during the hygienists' clinical education and/or during subsequent dental hygiene practice after one and/or two years. It was anticipated that the awkward positions and intense physical demands placed on hygienists might initiate musculoskeletal problems, but that no postural changes would occur over this short period of time. Nine of 10 dental hygienists in the graduating class of 1987 were surveyed for existing musculoskeletal complaints, and the subjects were photographed for a measurement of postural change. Responses from participants indicated an increase in musculoskeletal-related complaints in each of the six areas investigated. The photographic findings indicated that one of the nine hygienists showed an increase in forward head posture, a postural change.

  10. [Comparative analysis of one- and two-stage augmentation urethroplasty with dorsal INLAY buccal graft for extended stricturesof spongious urethra].

    Science.gov (United States)

    Kogan, M I; Glukhov, V P; Mitusov, V V; Krasulin, V V; Ilyash, A V

    2018-03-01

    Urethral reconstructive surgery is in constant development. At present, reconstructive urethroplasty with buccal mucosa is increasingly being used. The study aimed to compare the results of a one- and two-stage augmentation urethroplasty with dorsal inlay buccal graft for strictures of the spongious urethra. The study comprised 72 patients aged 19-64 with urethral strictures 3-18 cm long. In 34 (47.2%) patients, the stricture was localized in the penile urethra, in 30 patients (41.6%) in the penile-bulbous urethra and in 8 patients (11%) in the bulbous urethra. All patients underwent augmentation urethroplasty with dorsal inlay buccal graft. The results were evaluated separately in 55 (76.4%, group 1) and 17 (23.6%, group 2) patients who underwent one-stage and two-stage surgery, respectively. The incidence rate of early postoperative complications was higher after one-stage (23.6%) compared two-stage surgery (11.8%) (purethroplasty with dorsal inlay buccal graft was achieved in 88.9% of patients; treatment effectiveness in the group 1 was 89.1%, in the group 2 - 88.2% (p>0.05). The final effectiveness of the operation, achieved with the use of additional surgical interventions, is estimated at 98.6%. The results of augmentation urethroplasty with dorsal inlay buccal graft do not depend on the number of stages, but fewer complications accompany two-stage surgery.

  11. Impact of two-stage turbocharging architectures on pumping losses of automotive engines based on an analytical model

    International Nuclear Information System (INIS)

    Galindo, J.; Serrano, J.R.; Climent, H.; Varnier, O.

    2010-01-01

    Present work presents an analytical study of two-stage turbocharging configuration performance. The aim of this work is to understand the influence of different two-stage-architecture parameters to optimize the use of exhaust manifold gases energy and to aid decision making process. An analytical model giving the relationship between global compression ratio and global expansion ratio is developed as a function of basic engine and turbocharging system parameters. Having an analytical solution, the influence of different variables, such as expansion ratio between HP and LP turbine, intercooler efficiency, turbochargers efficiency, cooling fluid temperature and exhaust temperature are studied independently. Engine simulations with proposed analytical model have been performed to analyze the influence of these different parameters on brake thermal efficiency and pumping mean effective pressure. The results obtained show the overall performance of the two-stage system for the whole operative range and characterize the optimum control of the elements for each operative condition. The model was also used to compare single-stage and two-stage architectures performance for the same engine operative conditions. Benefits and limits in terms of breathing capabilities and brake thermal efficiency of each type of system have been presented and analyzed.

  12. Illumination uniformity issue explored via two-stage solar concentrator system based on Fresnel lens and compound flat concentrator

    International Nuclear Information System (INIS)

    Yeh, Naichia

    2016-01-01

    This paper illustrates details about the solar radiation distribution on the target of a two-stage solar concentrator that combines the Fresnel lens (FL) and the compound flat concentrator (CFC). The paper starts with a review of some FL development milestones such as the two-stage systems and the comparisons of flat vs. curved lenses in addition to the most noteworthy FL-based solar energy application, concentration photovoltaic (CPV). Through the review of the FL based CPV and two-stage concentrators, this study leads to the development of an algorithm to explore the spectrum distribution insight on the receiver of a two-stage (FL plus CFC) solar concentration system. It established the potential for using a correctly positioned 2nd stage reflector of right dimension to selectively redirect the desired spectrum on the target area so as to enhance the concentration flux intensity and uniformity at the same time. The study also helped to chart out the approximate locations of certain spectrum segments on the FL's target area, which is useful for exploring the spectrum control mechanism via the Fresnel lenses. - Highlights: • Map out the approximate locations of spectrum segments on FL's focal area. • Use the 2nd stage reflector to selectively reflect the desired spectrum on target. • Explore the spectrum distribution insight on FL solar concentrators' target area.

  13. Two stages and three components of the postural preparation to action.

    Science.gov (United States)

    Krishnan, Vennila; Aruin, Alexander S; Latash, Mark L

    2011-07-01

    Previous studies of postural preparation to action/perturbation have primarily focused on anticipatory postural adjustments (APAs), the changes in muscle activation levels resulting in the production of net forces and moments of force. We hypothesized that postural preparation to action consists of two stages: (1) Early postural adjustments (EPAs), seen a few hundred ms prior to an expected external perturbation and (2) APAs seen about 100 ms prior to the perturbation. We also hypothesized that each stage consists of three components, anticipatory synergy adjustments seen as changes in covariation of the magnitudes of commands to muscle groups (M-modes), changes in averaged across trials levels of muscle activation, and mechanical effects such as shifts of the center of pressure. Nine healthy participants were subjected to external perturbations created by a swinging pendulum while standing in a semi-squatting posture. Electrical activity of twelve trunk and leg muscles and displacements of the center of pressure were recorded and analyzed. Principal component analysis was used to identify four M-modes within the space of muscle activations using indices of integrated muscle activation. This analysis was performed twice, over two phases, 400-700 ms prior to the perturbation and over 200 ms just prior to the perturbation. Similar robust results were obtained using the data from both phases. An index of a multi-M-mode synergy stabilizing the center of pressure displacement was computed using the framework of the uncontrolled manifold hypothesis. The results showed high synergy indices during quiet stance. Each of the two stages started with a drop in the synergy index followed by a change in the averaged across trials activation levels in postural muscles. There was a very long electromechanical delay during the early postural adjustments and a much shorter delay during the APAs. Overall, the results support our main hypothesis on the two stages and three components

  14. Evaluation of a modified two-stage inferior alveolar nerve block technique: A preliminary investigation

    Directory of Open Access Journals (Sweden)

    Ashwin Rao

    2017-01-01

    Full Text Available Introduction: The two-stage technique of inferior alveolar nerve block (IANB administration does not address the pain associated with “needle insertion” and “local anesthetic solution deposition” in the “first stage” of the injection. This study evaluated a “modified two stage technique” to the reaction of children during “needle insertion” and “local anesthetic solution deposition” during the “first stage” and compared it to the “first phase” of the IANB administered with the standard one-stage technique. Materials and Methods: This was a parallel, single-blinded comparative study. A total of 34 children (between 6 and 10 years of age were randomly divided into two groups to receive an IANB either through the modified two-stage technique (MTST (Group A; 15 children or the standard one-stage technique (SOST (Group B; 19 children. The evaluation was done using the Face Legs Activity Cry Consolability (FLACC; which is an objective scale based on the expressions of the child scale. The obtained data was analyzed using Fishers Exact test with the P value set at <0.05 as level of significance. Results: 73.7% of children in Group B indicated moderate pain during the “first phase” of SOST and no children indicated such in the “first stage” of group A. Group A had 33.3% children who scored “0” indicating relaxed/comfortable children compared to 0% in Group B. In Group A, 66.7% of children scored between 1–3 indicating mild discomfort compared to 26.3% in group B. The difference in the scores between the two groups in each category (relaxed/comfortable, mild discomfort, moderate pain was highly significant (P < 0.001. Conclusion: Reaction of children in Group A during “needle insertion” and “local anesthetic solution deposition” in the “first stage” of MTST was significantly lower than that of Group B during the “first phase” of the SOST.

  15. Longitudinal Study: Efficacy of Online Technology Tools for Instructional Use

    Science.gov (United States)

    Uenking, Michael D.

    2011-01-01

    Studies show that the student population (secondary and post secondary) is becoming increasingly more technologically savvy. Use of the internet, computers, MP3 players, and other technologies along with online gaming has increased tremendously amongst this population such that it is creating an apparent paradigm shift in the learning modalities of these students. Instructors and facilitators of learning can no longer rely solely on traditional lecture-based lesson formals. In order to achieve student academic success and satisfaction and to increase student retention, instructors must embrace various technology tools that are available and employ them in their lessons. A longitudinal study (January 2009-June 2010) has been performed that encompasses the use of several technology tools in an instructional setting. The study provides further evidence that students not only like the tools that are being used, but prefer that these tools be used to help supplement and enhance instruction.

  16. A Longitudinal Examination of Childhood Maltreatment and Adolescent Obesity: Results from the National Longitudinal Study of Adolescent Health (AddHealth) Study

    Science.gov (United States)

    Shin, Sunny Hyucksun; Miller, Daniel P.

    2012-01-01

    Objectives: We sought to explore the association between childhood maltreatment (e.g., neglect, physical and sexual abuse) and longitudinal growth trajectories of body mass index (BMI) from adolescence to young adulthood. Methods: We used latent curve modeling to examine data from the National Longitudinal Study of Adolescent Health (N = 8,471),…

  17. A coupling model for the two-stage core calculation method with subchannel analysis for boiling water reactors

    International Nuclear Information System (INIS)

    Mitsuyasu, Takeshi; Aoyama, Motoo; Yamamoto, Akio

    2017-01-01

    Highlights: • A coupling model of the two-stage core calculation with subchannel analysis. • BWR fuel assembly parameters are assumed and verified. • The model was evaluated for heterogeneous problems. - Abstract: The two-stage core analysis method is widely used for BWR core analysis. The purpose of this study is to develop a core analysis model coupled with subchannel analysis within the two-stage calculation scheme using an assembly-based thermal-hydraulics calculation in the core analysis. The model changes the 2D lattice physics scheme, and couples with 3D subchannel analysis which evaluates the thermal-hydraulics characteristics within the coolant flow area divided as some subchannel regions. In order to couple with these two analyses, some BWR fuel assembly parameters are assumed and verified. The developed model is evaluated for the heterogeneous problem with and without a control rod. The present model is especially effective for the control rod inserted condition. The present model can incorporate the subchannel effect into the current two-stage core calculation method.

  18. A longitudinal study of adult foreign language learning

    DEFF Research Database (Denmark)

    Nielsen, Andreas Højlund; Horn, Nynne Thorup; Sørensen, Stine Derdau

    Models of speech learning suggest that adaptations to foreign language sound categories should happen early in the acquisition process. Results from laboratory language training show effects on non-native perception within one to three weeks of training. Results from linguistic immersion studies...... show differences in adaptations when contrasting averages of 1-2 yrs of experience with 6-7 yrs of experience. We investigated this apparent discrepancy in a longitudinal study on Danish language officer cadets learning either Arabic (MSA and Egyptian dialect) or Dari (Afghan Farsi) through intensive...... (emphatic frication) and a phonemic Dari contrast (fricative voicing) as stimuli for both groups. We saw an effect of learning on the Dari learners’ identification of the Dari stimuli already after three weeks of language training, which was sustained, but not improved, after six and 20 months. The extents...

  19. Hearing loss in the Royal Norwegian Navy: A longitudinal study.

    Science.gov (United States)

    Irgens-Hansen, Kaja; Baste, Valborg; Bråtveit, Magne; Lind, Ola; Koefoed, Vilhelm F; Moen, Bente E

    2016-01-01

    The aims of this longitudinal study were to investigate a significant threshold shift (STS) among personnel working on board the Royal Norwegian Navy's (RNoN) vessels between 2012 and 2014 and to identify possible determinants of STS. Hearing thresholds were measured by pure tone audiometry in two consecutive examinations (n = 226). STS was defined as an average change in hearing thresholds ≥ + 10 dB at 2,000 Hz, 3,000 Hz, and 4,000 Hz in either ear. Determinants of STS were assessed through a questionnaire. The incidence of STS was 23.0%. Significant determinants of STS were the number of episodes of temporary threshold shifts (TTS) in the Navy, exposure to continuous loud noise during work on board, and the number of gun shots (in the Navy, hunting, and sports). This study indicated a significant association between noise exposure on board Navy vessels and development of STS.

  20. Hearing loss in the Royal Norwegian Navy: A longitudinal study

    Directory of Open Access Journals (Sweden)

    Kaja Irgens-Hansen

    2016-01-01

    Full Text Available The aims of this longitudinal study were to investigate a significant threshold shift (STS among personnel working on board the Royal Norwegian Navy′s (RNoN vessels between 2012 and 2014 and to identify possible determinants of STS. Hearing thresholds were measured by pure tone audiometry in two consecutive examinations (n = 226. STS was defined as an average change in hearing thresholds ≥ + 10 dB at 2,000 Hz, 3,000 Hz, and 4,000 Hz in either ear. Determinants of STS were assessed through a questionnaire. The incidence of STS was 23.0%. Significant determinants of STS were the number of episodes of temporary threshold shifts (TTS in the Navy, exposure to continuous loud noise during work on board, and the number of gun shots (in the Navy, hunting, and sports. This study indicated a significant association between noise exposure on board Navy vessels and development of STS.

  1. Longitudinal study of spatial working memory development in young children.

    Science.gov (United States)

    Tsujii, Takeo; Yamamoto, Eriko; Masuda, Sayako; Watanabe, Shigeru

    2009-05-27

    This study longitudinally compared activity in the frontal cortex during a spatial working memory task between 5-year-old and 7-year-old children using near-infrared spectroscopy. Eight children participated in this study twice, once at 5 years and once at 7 years of age. Behavioral analysis showed that older children performed the working memory task more precisely and more rapidly than younger children. Near-infrared spectroscopy analysis showed that right hemisphere dominance was observed in older children, whereas no hemispheric difference was apparent in younger children. Children with strengthened lateralization showed improved performance from 5 to 7 years. We therefore offer the first demonstration of the developmental changes in frontal cortical activation during spatial working memory tasks during the preschool period.

  2. Two-stage autotransplantation of human submandibular gland: a novel approach to treat postradiogenic xerostomia.

    Science.gov (United States)

    Hagen, Rudolf; Scheich, Matthias; Kleinsasser, Norbert; Burghartz, Marc

    2016-08-01

    Xerostomia is a persistent side effect of radiotherapy (RT), which severely reduces the quality of life of the patients affected. Besides drug treatment and new irradiation strategies, surgical procedures aim for tissue protection of the submandibular gland. Using a new surgical approach, the submandibular gland was autotransplanted in 6 patients to the patient's forearm for the period of RT and reimplanted into the floor of the mouth 2-3 months after completion of RT. Saxon's test was performed during different time points to evaluate patient's saliva production. Furthermore patients had to answer EORTC QLQ-HN35 questionnaire and visual analog scale. Following this two-stage autotransplantation, xerostomia in the patients was markedly reduced due to improved saliva production of the reimplanted gland. Whether this promising novel approach is a reliable treatment option for RT patients in general should be evaluated in further studies.

  3. On the optimal use of a slow server in two-stage queueing systems

    Science.gov (United States)

    Papachristos, Ioannis; Pandelis, Dimitrios G.

    2017-07-01

    We consider two-stage tandem queueing systems with a dedicated server in each queue and a slower flexible server that can attend both queues. We assume Poisson arrivals and exponential service times, and linear holding costs for jobs present in the system. We study the optimal dynamic assignment of servers to jobs assuming that two servers cannot collaborate to work on the same job and preemptions are not allowed. We formulate the problem as a Markov decision process and derive properties of the optimal allocation for the dedicated (fast) servers. Specifically, we show that the one downstream should not idle, and the same is true for the one upstream when holding costs are larger there. The optimal allocation of the slow server is investigated through extensive numerical experiments that lead to conjectures on the structure of the optimal policy.

  4. The Sources of Efficiency of the Nigerian Banking Industry: A Two- Stage Approach

    Directory of Open Access Journals (Sweden)

    Frances Obafemi

    2013-11-01

    Full Text Available The paper employed a two-stage Data Envelopment Analysis (DEA approach to examine the sources oftechnical efficiency in the Nigerian banking sub-sector. Using a cross sectionof commercial and merchant banks, the study showed that the Nigerian bankingindustry was not efficient both in the pre-and-post-liberalization era. Thestudy further revealed that market share was the strongest determinant oftechnical efficiency in the Nigerian banking Industry. Thus, appropriatemacroeconomic policy, institutional development and structural reforms mustaccompany financial liberalization to create the stable environment requiredfor it to succeed. Hence, the present bank consolidation and reforms by theCentral Bank of Nigeria, which started with Soludo and continued with Sanusi,are considered necessary, especially in the areas of e banking and reorganizingthe management of banks.

  5. Hydrogen and methane production from household solid waste in the two-stage fermentation process

    DEFF Research Database (Denmark)

    Lui, D.; Liu, D.; Zeng, Raymond Jianxiong

    2006-01-01

    A two-stage process combined hydrogen and methane production from household solid waste was demonstrated working successfully. The yield of 43 mL H-2/g volatile solid (VS) added was generated in the first hydrogen production stage and the methane production in the second stage was 500 mL CH4/g VS...... added. This figure was 21% higher than the methane yield from the one-stage process, which was run as control. Sparging of the hydrogen reactor with methane gas resulted in doubling of the hydrogen production. PH was observed as a key factor affecting fermentation pathway in hydrogen production stage....... Furthermore, this study also provided direct evidence in the dynamic fermentation process that, hydrogen production increase was reflected by acetate to butyrate ratio increase in liquid phase. (c) 2006 Elsevier Ltd. All rights reserved....

  6. Discrete time population dynamics of a two-stage species with recruitment and capture

    International Nuclear Information System (INIS)

    Ladino, Lilia M.; Mammana, Cristiana; Michetti, Elisabetta; Valverde, Jose C.

    2016-01-01

    This work models and analyzes the dynamics of a two-stage species with recruitment and capture factors. It arises from the discretization of a previous model developed by Ladino and Valverde (2013), which represents a progress in the knowledge of the dynamics of exploited populations. Although the methods used here are related to the study of discrete-time systems and are different from those related to continuous version, the results are similar in both the discrete and the continuous case what confirm the skill in the selection of the factors to design the model. Unlike for the continuous-time case, for the discrete-time one some (non-negative) parametric constraints are derived from the biological significance of the model and become fundamental for the proofs of such results. Finally, numerical simulations show different scenarios of dynamics related to the analytical results which confirm the validity of the model.

  7. Stepwise encapsulation and controlled two-stage release system for cis-Diamminediiodoplatinum.

    Science.gov (United States)

    Chen, Yun; Li, Qian; Wu, Qingsheng

    2014-01-01

    cis-Diamminediiodoplatinum (cis-DIDP) is a cisplatin-like anticancer drug with higher anticancer activity, but lower stability and price than cisplatin. In this study, a cis-DIDP carrier system based on micro-sized stearic acid was prepared by an emulsion solvent evaporation method. The maximum drug loading capacity of cis-DIDP-loaded solid lipid nanoparticles was 22.03%, and their encapsulation efficiency was 97.24%. In vitro drug release in phosphate-buffered saline (pH =7.4) at 37.5°C exhibited a unique two-stage process, which could prove beneficial for patients with tumors and malignancies. MTT (3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay results showed that cis-DIDP released from cis-DIDP-loaded solid lipid nanoparticles had better inhibition activity than cis-DIDP that had not been loaded.

  8. Gastrocnemius muscle contracture after spinal cord injury: a longitudinal study.

    Science.gov (United States)

    Diong, Joanna; Harvey, Lisa A; Kwah, Li Khim; Clarke, Jillian L; Bilston, Lynne E; Gandevia, Simon C; Herbert, Robert D

    2013-07-01

    The aim of this study was to examine changes in passive length and stiffness of the gastrocnemius muscle-tendon unit in people after spinal cord injury. In a prospective longitudinal study, eight wheelchair-dependent participants with severe paralysis were assessed 3 and 12 mos after spinal cord injury. Passive torque-angle data were obtained as the ankle was slowly rotated through range at six knee angles. Differences in passive ankle torque-angle data recorded at different knee angles were used to derive passive length-tension curves of the gastrocnemius muscle-tendon unit. Ultrasound imaging was used to determine fascicle and tendon contributions to the muscle-tendon unit length-tension curves. The participants had ankle contractures (mean [SD] maximum passive ankle dorsiflexion angle, 88 [9] degrees) 3 mos after spinal cord injury. Ankle range did not worsen significantly during the subsequent 9 mos (mean change, -5 degrees; 95% confidence interval, -16 to 6 degrees). There were no changes in the mean slack length or the stiffness of the gastrocnemius muscle-tendon unit or in the slack lengths of the fascicles or the tendon between 3 and 12 mos after spinal cord injury. There were no consistent patterns of the change in slack length or stiffness with the changes in ankle range in the data from the individual participants. This study, the first longitudinal study of muscle length and stiffness after spinal cord injury, showed that the length and the stiffness of the gastrocnemius did not change substantially between 3 and 12 mos after injury.

  9. Optimal design of distributed energy resource systems based on two-stage stochastic programming

    International Nuclear Information System (INIS)

    Yang, Yun; Zhang, Shijie; Xiao, Yunhan

    2017-01-01

    Highlights: • A two-stage stochastic programming model is built to design DER systems under uncertainties. • Uncertain energy demands have a significant effect on the optimal design. • Uncertain energy prices and renewable energy intensity have little effect on the optimal design. • The economy is overestimated if the system is designed without considering the uncertainties. • The uncertainty in energy prices has the significant and greatest effect on the economy. - Abstract: Multiple uncertainties exist in the optimal design of distributed energy resource (DER) systems. The expected energy, economic, and environmental benefits may not be achieved and a deficit in energy supply may occur if the uncertainties are not handled properly. This study focuses on the optimal design of DER systems with consideration of the uncertainties. A two-stage stochastic programming model is built in consideration of the discreteness of equipment capacities, equipment partial load operation and output bounds as well as of the influence of ambient temperature on gas turbine performance. The stochastic model is then transformed into its deterministic equivalent and solved. For an illustrative example, the model is applied to a hospital in Lianyungang, China. Comparative studies are performed to evaluate the effect of the uncertainties in load demands, energy prices, and renewable energy intensity separately and simultaneously on the system’s economy and optimal design. Results show that the uncertainties in load demands have a significant effect on the optimal system design, whereas the uncertainties in energy prices and renewable energy intensity have almost no effect. Results regarding economy show that it is obviously overestimated if the system is designed without considering the uncertainties.

  10. Anti-kindling induced by two-stage coordinated reset stimulation with weak onset intensity

    Directory of Open Access Journals (Sweden)

    Magteld eZeitler

    2016-05-01

    Full Text Available Abnormal neuronal synchrony plays an important role in a number of brain diseases. To specifically counteract abnormal neuronal synchrony by desynchronization, Coordinated Reset (CR stimulation, a spatiotemporally patterned stimulation technique, was designed with computational means. In neuronal networks with spike timing–dependent plasticity CR stimulation causes a decrease of synaptic weights and finally anti-kindling, i.e. unlearning of abnormally strong synaptic connectivity and abnormal neuronal synchrony. Long-lasting desynchronizing aftereffects of CR stimulation have been verified in pre-clinical and clinical proof of concept studies. In general, for different neuromodulation approaches, both invasive and non-invasive, it is desirable to enable effective stimulation at reduced stimulation intensities, thereby avoiding side effects. For the first time, we here present a two-stage CR stimulation protocol, where two qualitatively different types of CR stimulation are delivered one after another, and the first stage comes at a particularly weak stimulation intensity. Numerical simulations show that a two-stage CR stimulation can induce the same degree of anti-kindling as a single-stage CR stimulation with intermediate stimulation intensity. This stimulation approach might be clinically beneficial in patients suffering from brain diseases characterized by abnormal neuronal synchrony where a first treatment stage should be performed at particularly weak stimulation intensities in order to avoid side effects. This might, e.g., be relevant in the context of acoustic CR stimulation in tinnitus patients with hyperacusis or in the case of electrical deep brain CR stimulation with sub-optimally positioned leads or side effects caused by stimulation of the target itself. We discuss how to apply our method in first in man and proof of concept studies.

  11. Two-stage double-effect ammonia/lithium nitrate absorption cycle

    International Nuclear Information System (INIS)

    Ventas, R.; Lecuona, A.; Vereda, C.; Legrand, M.

    2016-01-01

    Highlights: • A two stage double effect cycle with NH3-LiNO3 is proposed. • The cycle operates at lower pressures than conventional. • Adiabatic absorber offers better performance than the diabatic version. • Evaporator external inlet temperatures higher than −10 °C avoids crystallization. • Maximum COP is 1.25 for driving water inlet temperature of 100 C. - Abstract: The two-stage configuration of a double-effect absorption cycle using ammonia/lithium nitrate as working fluid is studied by means of a thermodynamic model. The maximum pressure of this cycle configuration is the same as the single-effect cycle, up to 15.8 bars, being an advantage over the double-effect conventional configuration with three pressure levels that exhibits much higher maximum pressure. The performance of the cycle and the limitation imposed by crystallization of the working fluid is determined for both adiabatic and diabatic absorber cycles. Both cycles offer similar COP; however the adiabatic variant shows a larger margin against crystallization. This cycle can produce cold for external inlet evaporator temperatures down to −10 °C, but for this limit the crystallization could happen at high inlet generator temperatures. The maximum COP can be 1.25 for an external inlet generator temperature of 100 °C. This cycle shows a better COP than a typical double effect cycle with in-parallel configuration for the range of the moderate temperatures under study and using the same working fluid. Comparisons with double effect cycles using H_2O/LiBr and NH_3/H_2O as working fluids are also offered, highlighting the present configurations advantages regarding COP, evaporation and condensation temperatures as well as crystallization.

  12. An unit cost adjusting heuristic algorithm for the integrated planning and scheduling of a two-stage supply chain

    Directory of Open Access Journals (Sweden)

    Jianhua Wang

    2014-10-01

    Full Text Available Purpose: The stable relationship of one-supplier-one-customer is replaced by a dynamic relationship of multi-supplier-multi-customer in current market gradually, and efficient scheduling techniques are important tools of the dynamic supply chain relationship establishing process. This paper studies the optimization of the integrated planning and scheduling problem of a two-stage supply chain with multiple manufacturers and multiple retailers to obtain a minimum supply chain operating cost, whose manufacturers have different production capacities, holding and producing cost rates, transportation costs to retailers.Design/methodology/approach: As a complex task allocation and scheduling problem, this paper sets up an INLP model for it and designs a Unit Cost Adjusting (UCA heuristic algorithm that adjust the suppliers’ supplying quantity according to their unit costs step by step to solve the model.Findings: Relying on the contrasting analysis between the UCA and the Lingo solvers for optimizing many numerical experiments, results show that the INLP model and the UCA algorithm can obtain its near optimal solution of the two-stage supply chain’s planning and scheduling problem within very short CPU time.Research limitations/implications: The proposed UCA heuristic can easily help managers to optimizing the two-stage supply chain scheduling problems which doesn’t include the delivery time and batch of orders. For two-stage supply chains are the most common form of actual commercial relationships, so to make some modification and study on the UCA heuristic should be able to optimize the integrated planning and scheduling problems of a supply chain with more reality constraints.Originality/value: This research proposes an innovative UCA heuristic for optimizing the integrated planning and scheduling problem of two-stage supply chains with the constraints of suppliers’ production capacity and the orders’ delivering time, and has a great

  13. Comparison of Oone-Stage Free Gracilis Muscle Flap With Two-Stage Method in Chronic Facial Palsy

    Directory of Open Access Journals (Sweden)

    J Ghaffari

    2007-08-01

    Full Text Available Background:Rehabilitation of facial paralysis is one of the greatest challenges faced by reconstructive surgeons today. The traditional method for treatment of patients with facial palsy is the two-stage free gracilis flap which has a long latency period of between the two stages of surgery.Methods: In this paper, we prospectively compared the results of the one-stage gracilis flap method with the two -stage technique.Results:Out of 41 patients with facial palsy refered to Hazrat-e-Fatemeh Hospital 31 were selected from whom 22 underwent two- stage and 9 one-stage method treatment. The two groups were identical according to age,sex,intensity of illness, duration, and chronicity of illness. Mean duration of follow up was 37 months. There was no significant relation between the two groups regarding the symmetry of face in repose, smiling, whistling and nasolabial folds. Frequency of complications was equal in both groups. The postoperative surgeons and patients' satisfaction were equal in both groups. There was no significant difference between the mean excursion of muscle flap in one-stage (9.8 mm and two-stage groups (8.9 mm. The ratio of contraction of the affected side compared to the normal side was similar in both groups. The mean time of the initial contraction of the muscle flap in the one-stage group (5.5 months had a significant difference (P=0.001 with the two-stage one (6.5 months.The study revealed a highly significant difference (P=0.0001 between the mean waiting period from the first operation to the beginning of muscle contraction in one-stage(5.5 monthsand two-stage groups(17.1 months.Conclusion:It seems that the results and complication of the two methods are the same,but the one-stage method requires less time for facial reanimation,and is costeffective because it saves time and decreases hospitalization costs.

  14. Confounding adjustment through front-door blocking in longitudinal studies

    Directory of Open Access Journals (Sweden)

    Arvid Sjölander

    2013-03-01

    Full Text Available A common aim of epidemiological research is to estimate the causal effect of a particular exposure on a particular outcome. Towards this end, observed associations are often ‘adjusted’ for potential confounding variables. When the potential confounders are unmeasured, explicit adjustment becomes unfeasible. It has been demonstrated that causal effects can be estimated even in the presence of umeasured confounding, utilizing a method called ‘front-door blocking’. In this paper we generalize this method to longitudinal studies. We demonstrate that the method of front-door blocking poses a number of challenging statistical problems, analogous to the famous problems associ- ated with the method of ‘back-door blocking’.

  15. [Autoaggression and pulse rate--a longitudinal study].

    Science.gov (United States)

    Rohmann, U H; Elbing, U; Hartmann, H

    1988-12-01

    This article presents a model of autoaggressive behavior in which a distinction is made between determining and maintaining factors. Specific environmental, in particular social, and organismic variables are linked to them. The two types of variables interact, thus causing or maintaining autoaggressive behavior. A theory of autoaggression must therefore rely on multicausal/multimodal explanations. A connection between autoaggression and a high level of arousal suggests itself. In this single-case longitudinal study a comparison was made between heart rate and frequency of autoaggressive behavior. High heart rates were found to be correlated with low frequencies of autoaggressive behavior and vice versa. Decreasing autoaggressive behavior was coupled with increasing muscle relaxation and increasing motor activity. However, abnormally high heart rates were associated with both low and high levels of motor activity.

  16. Design of a Two-Stage Light Gas Gun for Muzzle Velocities of 10 - 11 kms

    Science.gov (United States)

    Bogdanoff, David W.

    2016-01-01

    Space debris poses a major risk to spacecraft. In low earth orbit, impact velocities can be 10 11 kms and as high as 15 kms. For debris shield design, it would be desirable to be able to launch controlled shape projectiles to these velocities. The design of the proposed 10 11 kmsec gun uses, as a starting point, the Ames 1.280.22 two stage gun, which has achieved muzzle velocities of 10 11.3 kmsec. That gun is scaled up to a 0.3125 launch tube diameter. The gun is then optimized with respect to maximum pressures by varying the pump tube length to diameter ratio (LD), the piston mass and the hydrogen pressure. A pump tube LD of 36.4 is selected giving the best overall performance. Piezometric ratios for the optimized guns are found to be 2.3, much more favorable than for more traditional two stage light gas guns, which range from 4 to 6. The maximum powder chamber pressures are 20 to 30 ksi. To reduce maximum pressures, the desirable range of the included angle of the cone of the high pressure coupling is found to be 7.3 to 14.6 degrees. Lowering the break valve rupture pressure is found to lower the maximum projectile base pressure, but to raise the maximum gun pressure. For the optimized gun with a pump tube LD of 36.4, increasing the muzzle velocity by decreasing the projectile mass and increasing the powder loads is studied. It appears that saboted spheres could be launched to 10.25 and possibly as high as 10.7 10.8 kmsec, and that disc-like plastic models could be launched to 11.05 kms. The use of a tantalum liner to greatly reduce bore erosion and increase muzzle velocity is discussed. With a tantalum liner, CFD code calculations predict muzzle velocities as high as 12 to 13 kms.

  17. Longitudinal study of body composition in spinal cord injury patients

    Directory of Open Access Journals (Sweden)

    Roop Singh

    2014-01-01

    Full Text Available Background: Bone mass loss and muscle atrophy are the frequent complications occurring after spinal cord injury (SCI. The potential risks involved with these changes in the body composition have implications for the health of the SCI individual. Thus, there is a need to quantitate and monitor body composition changes accurately in an individual with SCI. Very few longitudinal studies have been reported in the literature to assess body composition and most include relatively small number of patients. The present prospective study aimed to evaluate the body composition changes longitudinally by DEXA in patients with acute SCI. Materials and Methods: Ninety five patients with acute SCI with neurological deficits were evaluated for bone mineral content (BMC, body composition [lean body mass (LBM and fat mass] by dual-energy X-ray absorptiometry during the first year of SCI. Results: There was a significant decrease in BMC ( P < 0.05 and LBM ( P < 0.05 and increase in total body fat mass (TBFM and percentage fat at infra-lesional sites. The average decrease was 14.5% in BMC in lower extremities, 20.5% loss of LBM in legs and 15.1% loss of LBM in trunk, and increase of 0.2% in fat mass in legs and 17.3% increased fat in the lower limbs at 1 year. The tetraplegic patients had significant decrease in arm BMC ( P < 0.001, arm LBM ( P < 0.01 and fat percentage ( P < 0.01 compared to paraplegics. Patients with complete motor injury had higher values of TBFM and fat percentage, but comparable values of BMC and LBM to patients with incomplete motor injury. Conclusions: Our findings suggest that there is a marked decrease in BMC and LBM with increase in adiposity during the first year of SCI. Although these changes depend on the level and initial severity of lesions, they are also influenced by the neurological recovery after SCI.

  18. Design considerations for single-stage and two-stage pneumatic pellet injectors

    International Nuclear Information System (INIS)

    Gouge, M.J.; Combs, S.K.; Fisher, P.W.; Milora, S.L.

    1988-09-01

    Performance of single-stage pneumatic pellet injectors is compared with several models for one-dimensional, compressible fluid flow. Agreement is quite good for models that reflect actual breech chamber geometry and incorporate nonideal effects such as gas friction. Several methods of improving the performance of single-stage pneumatic pellet injectors in the near term are outlined. The design and performance of two-stage pneumatic pellet injectors are discussed, and initial data from the two-stage pneumatic pellet injector test facility at Oak Ridge National Laboratory are presented. Finally, a concept for a repeating two-stage pneumatic pellet injector is described. 27 refs., 8 figs., 3 tabs

  19. Parent and Child Cigarette Use: A Longitudinal, Multigenerational Study

    Science.gov (United States)

    Staff, Jeremy

    2013-01-01

    OBJECTIVES: Using longitudinal data from the multigenerational Youth Development Study (YDS), this article documents how parents’ long-term smoking trajectories are associated with adolescent children’s likelihood of smoking. Prospective data from the parents (from age 14–38 years) enable unique comparisons of the parents’ and children’s smoking behavior, as well as that of siblings. METHODS: Smoking trajectories are constructed using latent class analysis for the original YDS cohort (n = 1010). Multigenerational longitudinal data from 214 parents and 314 offspring ages 11 years and older are then analyzed by using logistic regression with cluster-corrected SEs. RESULTS: Four latent smoking trajectories emerged among the original cohort: stable nonsmokers (54%), early-onset light smokers who quit/reduce (16%), late-onset persistent smokers (14%), and early-onset persistent heavy smokers (16%). Although 8% of children of stable nonsmokers smoked in the last year, the other groups’ children had much higher percentages, ranging from 23% to 29%. Multivariate logistic regression models confirm that these significant differences were robust to the inclusion of myriad child- and parent-level measures (for which child age and grade point average [GPA] are significant predictors). Older sibling smoking, however, mediated the link between parental heavy smoking and child smoking. CONCLUSIONS: Even in an era of declining rates of teenage cigarette use in the United States, children of current and former smokers face an elevated risk of smoking. Prevention efforts to weaken intergenerational associations should consider parents’ long-term cigarette use, as well as the smoking behavior of older siblings in the household. PMID:23918887

  20. Muscle reinnervation in one or two stages?: experimental study in rats with end-to-side nerve graft Reinervação muscular em um ou dois estágios?: estudo experimental em ratos com enxerto de nervo término-lateral

    Directory of Open Access Journals (Sweden)

    Joseli Assem Bersaneti

    2012-12-01

    Full Text Available PURPOSE: To compare muscle reinnervation in one and two surgical stages using end-to-side neurorrhaphy (ESN without donor nerve injury. METHODS: The experiment was performed on four groups of 20 rats. Group 1 (G1, one stage, received the graft which was sutured to the tibial nerve, with ESN, and its free stump was sutured end-to-end to the distal stump of the sectioned peroneal nerve (PN, all in the same operation. In Group 2 (G2, two stages, the nerve graft was sutured to the tibial nerve, with ESN. Two months later the PN was sectioned and its distal stump connected to the distal stump of the graft as in G1. Normal control group (Gn received the graft only sutured to the tibial nerve, with ESN. Denervated control group (Gd, as well received the graft and had the PN sectioned and its two stumps buried in adjacent musculature, with the aim of denervating the cranial tibial muscle (CTM, the target of this study. The parameters used to evaluate CTM reinnervation were muscle mass, muscle fiber's minimum diameter and area. RESULTS: The mean CTM mass, the average of the muscular fibers areas and the average of the muscular fiber minimum diameters was higher (all pOBJETIVO: Comparar a reinervação muscular com enxerto de nervo em um e dois tempos operatórios, utilizando a neurorrafia término-lateral (NTL sem lesão do nervo doador. MÉTODOS: Vinte ratos foram distribuídos em quatro grupos. O grupo 1 (G1, um estágio, recebeu o enxerto que foi suturado ao nervo tibial (NT, por meio de NTL, e seu coto livre foi suturado por NTL ao coto distal do nervo peroneal (NP, seccionado a um centímetro do NT, na mesma cirurgia. O grupo 2 (G2, dois estágios, recebeu o enxerto de nervo na primeira cirurgia, como já descrito. Dois meses depois, na segunda cirurgia, o NP foi seccionado e seu coto distal ligado ao coto distal do enxerto como em G1. O grupo controle de normalidade (Gn recebeu o enxerto da mesma forma, apenas. E o grupo controle de denerva

  1. Hydrogen production from cellulose in a two-stage process combining fermentation and electrohydrogenesis

    KAUST Repository

    Lalaurette, Elodie; Thammannagowda, Shivegowda; Mohagheghi, Ali; Maness, Pin-Ching; Logan, Bruce E.

    2009-01-01

    A two-stage dark-fermentation and electrohydrogenesis process was used to convert the recalcitrant lignocellulosic materials into hydrogen gas at high yields and rates. Fermentation using Clostridium thermocellum produced 1.67 mol H2/mol

  2. Lingual mucosal graft two-stage Bracka technique for redo hypospadias repair

    Directory of Open Access Journals (Sweden)

    Ahmed Sakr

    2017-09-01

    Conclusion: Lingual mucosa is a reliable and versatile graft material in the armamentarium of two-stage Bracka hypospadias repair with the merits of easy harvesting and minor donor-site complications.

  3. TWO-STAGE CHARACTER CLASSIFICATION : A COMBINED APPROACH OF CLUSTERING AND SUPPORT VECTOR CLASSIFIERS

    NARCIS (Netherlands)

    Vuurpijl, L.; Schomaker, L.

    2000-01-01

    This paper describes a two-stage classification method for (1) classification of isolated characters and (2) verification of the classification result. Character prototypes are generated using hierarchical clustering. For those prototypes known to sometimes produce wrong classification results, a

  4. Cost-effectiveness Analysis of a Two-stage Screening Intervention for Hepatocellular Carcinoma in Taiwan

    Directory of Open Access Journals (Sweden)

    Sophy Ting-Fang Shih

    2010-01-01

    Conclusion: Screening the population of high-risk individuals for HCC with the two-stage screening intervention in Taiwan is considered potentially cost-effective compared with opportunistic screening in the target population of an HCC endemic area.

  5. A Two-Stage Fuzzy Logic Control Method of Traffic Signal Based on Traffic Urgency Degree

    OpenAIRE

    Yan Ge

    2014-01-01

    City intersection traffic signal control is an important method to improve the efficiency of road network and alleviate traffic congestion. This paper researches traffic signal fuzzy control method on a single intersection. A two-stage traffic signal control method based on traffic urgency degree is proposed according to two-stage fuzzy inference on single intersection. At the first stage, calculate traffic urgency degree for all red phases using traffic urgency evaluation module and select t...

  6. Noncausal two-stage image filtration at presence of observations with anomalous errors

    OpenAIRE

    S. V. Vishnevyy; S. Ya. Zhuk; A. N. Pavliuchenkova

    2013-01-01

    Introduction. It is necessary to develop adaptive algorithms, which allow to detect such regions and to apply filter with respective parameters for suppression of anomalous noises for the purposes of image filtration, which consist of regions with anomalous errors. Development of adaptive algorithm for non-causal two-stage images filtration at pres-ence of observations with anomalous errors. The adaptive algorithm for noncausal two-stage filtration is developed. On the first stage the adaptiv...

  7. Chronic pain in multiple sclerosis: A 10-year longitudinal study.

    Science.gov (United States)

    Young, Jamie; Amatya, Bhasker; Galea, Mary P; Khan, Fary

    2017-07-01

    Pain is a common symptom associated with multiple sclerosis (MS), and has lasting effects on an individual's functional capacity and quality of life. A wide range of prevalence rates of pain (between 23% and 90%)have been reported in MS and this is mainly due to the methodological differences amongst the studies such as variability in patient sources, method of sampling and the definition of pain used. Chronic pain in MS, defined as pain lasting for greater than 3-6 months, can have a significant impact on their biopsychosocial health, including negative impact on activities of daily living, relationships and social participation. The long-term course of MS-related pain and its impact in an Australian cohort over a 7-year period has been investigated earlier. The aim of this longitudinal study was to describe the impact of chronic pain, pain-related disability and carer burden in persons with MS over a 10-year period. The aim of this longitudinal study was to describe the impact of chronic pain, pain-related disability and carer burden in persons with MS over a 10-year period. This was a prospective longitudinal study conducted at the Rehabilitation Department of Royal Melbourne Hospital (RMH), a tertiary referral hospital in Victoria and Australia. The source of participants was from the RMH MS database and contains detailed MS patient information including demographic data, diagnosis details (using McDonald's criteria), pain characteristics. Structured face-face interviews and validated measures were used, which include the visual analogue scale (VAS); chronic pain grade (CPG); the assessment of quality of life (AQoL) and the carer strain index (CSI). The mean age of the participants (n=70) was 55.3 years and majority (70%) were female. The mean age of the participants (n=70) was 55.3 years and majority (70%) were female. The findings show that over time (10 years), participants report having greater bilateral bodily pain and greater description of pain as 'worse

  8. Prediction of the development of reading comprehension: a longitudinal study

    NARCIS (Netherlands)

    Verhoeven, L.T.W.; Leeuwe, J.F.J. van

    2008-01-01

    Specific effects of word decoding, vocabulary and listening comprehension abilities on the development of reading comprehension were longitudinally examined for a representative sample of 2143 Dutch children throughout the elementary school period. An attempt was made to test two theoretical

  9. Parental influences on adolescent physical activity: a longitudinal study

    Directory of Open Access Journals (Sweden)

    Ayala Guadalupe X

    2007-02-01

    Full Text Available Abstract Background Physical inactivity is increasing among adolescents in the U.S., especially among girls. Despite growing evidence that parents are an important influence on adolescent health, few longitudinal studies have explored the causal relationship between parental influence and physical activity. This study examines how the relationships between parental influences and adolescent physical activity differ by gender and tests whether these relationships are mediated by adolescents' self-esteem and depression. Methods Data are from the National Longitudinal Study of Adolescent Health. The sample includes 13,246 youth, grades 7 to 12, interviewed in 1995 and again 1 year later. Logit models were used to evaluate parental influences on achieving five or more bouts of moderate to vigorous physical activity per week [MVPA] and whether the relationship between parental influence and MVPA was mediated by adolescents' level of self-esteem and depression. Results Family cohesion, parent-child communication and parental engagement positively predicted MVPA for both genders one year later (odds ratios and 95% confidence intervals for females, 1.09 [1.05–1.12], 1.13 [1.07–1.19], 1.25 [1.17–1.33] and males, 1.08 [1.04–1.11], 1.14 [1.07–1.23], 1.23 [1.14–1.33], respectively; however, parental monitoring did not (odds ratio and confidence intervals for females and males, 1.02 [.97–1.07]. For both females and males, self-esteem mediated the relationship between parental influence and physical activity. Depressive symptoms were only a mediator among males. Females reported higher levels of parent-child communication and lower family cohesion compared with males. There were no gender differences in levels of parental monitoring and engagement. Females had significantly lower levels of self-esteem and higher levels of depressive symptoms than males. Conclusion Strategies to promote physical activity among adolescents should focus on

  10. Studies of the longitudinal instability with an electron beam

    International Nuclear Information System (INIS)

    1993-01-01

    Goals for our first-year period are as follows: To study the evolution of a small perturbation in the current pulse (introduced via the grid voltage on the electron gun) when the beam propagates through our 5-m long periodic solenoid channel. Specifically, to see if the perturbation is reflected from the rear end of the pulse. So far these objectives have been met without any delays. We were able to launch different perturbations on the beam resulting in either a slow space-charge wave or a fast wave or both waves. The relative strength of each wave was found to depend on the electron emission temperature of the cathode. The propagation of these waves on an initially rectangular longitudinal beam profile was measured with fast current monitors and the kinetic energy was measured with sensitive energy analyzers at various positions along the 5-m long solenoidal focusing channel. We have also begun to study the behavior of the waves when they reach the respective edge of the beam. But this work is still of a preliminary nature, and we need to refine the beam conditions and measurements in future studies to reach any firm conclusions. Preparations for the resistive-wall instability experiment are in progress

  11. A longitudinal study of language learners’ images about Russia

    Directory of Open Access Journals (Sweden)

    Nikitina Larisa

    2016-05-01

    Full Text Available Several studies in the field of applied linguistics have explored images held by language learners about a target language country. However, for the most part, these studies focused on learners of modern European languages, such as German, Spanish and French and they were conducted in Western educational contexts. Besides, none of the previous investigations attempted to conduct a systematic classification of the language learners’ images. The present longitudinal study addressed these gaps in the research literature. It explored images about Russia held by Malaysian learners of the Russian language in a large university in East Malaysia. This article reports the findings of three questionnaire surveys conducted in 2004, 2007 and 2010. It was found that the images about Russia held by the participants were diverse and clustered around eight countryrelated aspects. Content of some categories of images was stable and changed little over time. Other categories were more fluid and more prone to change. The paper concludes with a discussion of pedagogical implications that can be derived from the findings.

  12. Becoming a mental health nurse; A three year longitudinal study

    Directory of Open Access Journals (Sweden)

    Harvey Wells

    2015-03-01

    Full Text Available This longitudinal case series study explores how students’ conceptions of ‘mental health nursing’ changed whilst on a three-year pre-registration Mental Health Nursing programme. The study was carried out in two university nursing schools in the South East of England and this paper reports a detailed analysis of 6 individual case studies. The researchers utilised Novak’s approach to concept mapping to elicit students’ personal knowledge structures, which were explored further using semi-structured individual qualitative interviews. The maps were analysed by looking at their gross morphology to interpret changes over time into types of learning achieved and the associated interview data were analysed using thematic content analysis. Results from analysis of the map structures suggest that whilst four of the selected students learned deeply, one participant learned superficially and one appeared not to learn at all. The associated interview data provides an interesting insight into the students’ reflective narratives on the process of learning. The findings also demonstrate further evidence of the practicability of using Novakian concept maps to self-prompt qualitative research interviews. Implications for the professional education of Mental Health Nurses are discussed.

  13. Clustering of unhealthy behaviors in the aerobics center longitudinal study.

    Science.gov (United States)

    Héroux, Mariane; Janssen, Ian; Lee, Duck-chul; Sui, Xuemei; Hebert, James R; Blair, Steven N

    2012-04-01

    Clustering of unhealthy behaviors has been reported in previous studies; however the link with all-cause mortality and differences between those with and without chronic disease requires further investigation. To observe the clustering effects of unhealthy diet, fitness, smoking, and excessive alcohol consumption in adults with and without chronic disease and to assess all-cause mortality risk according to the clustering of unhealthy behaviors. Participants were 13,621 adults (aged 20-84) from the Aerobics Center Longitudinal Study. Four health behaviors were observed (diet, fitness, smoking, and drinking). Baseline characteristics of the study population and bivariate relations between pairs of the health behaviors were evaluated separately for those with and without chronic disease using cross-tabulation and a chi-square test. The odds of partaking in unhealthy behaviors were also calculated. Latent class analysis (LCA) was used to assess clustering. Cox regression was used to assess the relationship between the behaviors and mortality. The four health behaviors were related to each other. LCA results suggested that two classes existed. Participants in class 1 had a higher probability of partaking in each of the four unhealthy behaviors than participants in class 2. No differences in health behavior clustering were found between participants with and without chronic disease. Mortality risk increased relative to the number of unhealthy behaviors participants engaged in. Unhealthy behaviors cluster together irrespective of chronic disease status. Such findings suggest that multi-behavioral intervention strategies can be similar in those with and without chronic disease.

  14. The USA National Longitudinal Lesbian Family Study (NLLFS): homophobia, psychological adjustment, and protective factors

    NARCIS (Netherlands)

    Bos, H.M.W.; Gartrell, N.K.; Peyser, H.; van Balen, F.

    2008-01-01

    The study assessed the influence of protective factors on the psychological adjustment of children who had experienced homophobia and whose mothers were participants in a longitudinal study of planned lesbian families. Data were collected as part of the National Longitudinal Lesbian Family Study by

  15. Stress Process of Illicit Drug Use among U.S. Immigrants' Adolescent Children: A Longitudinal Study

    Science.gov (United States)

    Choo, Hyekyung

    2012-01-01

    This study examined a full path model of stress process for predicting illicit drug use among Asian and Latino immigrants' adolescent children. Using 2-year longitudinal data (National Longitudinal Study of Adolescent Health) from a sample of adolescents with Asian or Latino immigrant parents (N = 2,353), the study explored structural…

  16. Insights from an 8-Year Longitudinal Study of Female REU Participants

    Science.gov (United States)

    Slater, S. J.

    2009-12-01

    The long-running REU program is tacitly intended to increase retention and provide "an important educational experience" for undergraduates, particularly women, minorities and underrepresented groups. This 8-year, two-stage study was designed to explore the ways in which the REU acted as an educational experience for 51 women from a single scientific discipline. This paper describes the results of that analysis in two sections. The first section describes the results from an ex post facto longitudinal data analysis. This data included multiple interviews with each participant during their REU, annual open-ended alumni surveys, faculty interviews, and extensive field notes, over an 8-year period. As a result of this analysis, four themes emerged, related to developing understandings of the nature of professional scientific work, the nature of the scientific process, the culture of academia, and finally, an understanding of the "self." This analysis served as an initial theory that was used to design the second stage, interview protocol. In the second stage over 10 hours of interviews with 8 participants were conducted and analyzed. These 8 participants were selected to represent a variety of career stages, and for their potential to disconfirm the initial theory. Analysis of this interview data failed to provide disconfirming evidence. Results from this study indicate that the REU did not provide a substantive educational experience related to the nature of scientific work, the scientific process, or the culture of academia. Results further indicated that the REU did not serve to transform participants' conceptions about themselves as situated in science, and learning gains with regard to other aspects of the self, were somewhat limited. Instead, the data suggests that these women arrived at the REU with pre-existing and remarkably strong conceptions in these areas, and that the REU did not functional to alter those states. These conceptions were frequently the

  17. Natural course of behavioral addictions: a 5-year longitudinal study.

    Science.gov (United States)

    Konkolÿ Thege, Barna; Woodin, Erica M; Hodgins, David C; Williams, Robert J

    2015-01-22

    Resolving the theoretical controversy on the labeling of an increasing number of excessive behaviors as behavioral addictions may also be facilitated by more empirical data on these behavioral problems. For instance, an essential issue to the classification of psychiatric disorders is information on their natural course. However, longitudinal research on the chronic vs. episodic nature of behavioral addictions is scarce. The aim of the present study, therefore, was to provide data on prevalence, substance use comorbidity, and five-year trajectories of six excessive behaviors-namely exercising, sexual behavior, shopping, online chatting, video gaming, and eating. Analyses were based on the data of the Quinte Longitudinal Study, where a cohort of 4,121 adults from Ontario, Canada was followed for 5 years (2006 to 2011). The response rate was 21.3%, while retention rate was 93.9%. To assess the occurrence of each problem behavior, a single self-diagnostic question asked people whether their over-involvement in the behavior had caused significant problems for them in the past 12 months. To assess the severity of each problem behavior reported, the Behavioral Addiction Measure was administered. A mixed design ANOVA was used to investigate symptom trajectories over time for each problem behavior and whether these symptom trajectories varied as a function of sex. The large majority of people reported having problematic over-involvement for just one of these behaviors and just in a single time period. A main effect of time was found for each problem behavior, indicating a moderately strong decrease in symptom severity across time. The time x sex interaction was insignificant in each model indicating that the decreasing trend is similar for males and females. The data also showed that help seeking was very low in the case of excessive sexual behavior, shopping, online chatting, and video gaming but substantially more prevalent in the case of excessive eating and

  18. Longitudinal study of prognostic factors in established periodontitis patients.

    Science.gov (United States)

    Machtei, E E; Dunford, R; Hausmann, E; Grossi, S G; Powell, J; Cummins, D; Zambon, J J; Genco, R J

    1997-02-01

    Numerous indicators for disease progression have been described in the last decade. The purpose of this study was to examine, longitudinally, a large battery of clinical, microbiological, and immunological indicators, to try to determine whether the presence of one or a combination of these parameters at baseline, would correlate positively with increased attachment and or bone loss (true prognostic factors). Following initial screening, 79 patients with established periodontitis were monitored longitudinally for one year. Whole mouth clinical measurements, plaque gingival and calculus indices, together with pocket depth and attachment level measurements, were repeated every three months. Full mouth radiographic survey, performed at baseline and 12 months, served to determine changes in crestal bone height using an image enhancement technique. Subgingival plaque samples were taken at baseline and every 3 months. Immunofluorescence assays were performed for the a battery of target microorganisms. Serum and GCF samples for IgG subclasses analysis were obtained at each visit and assayed using ELISA techniques. Likewise blood, samples were also drawn at each visit for a quantitative analysis of serum cotinine level. The overall mean attachment loss (AL) and bone loss (BL) were almost identical (0.159 mm and 0.164 mm, respectively). Individual patients variation was large (-0.733 to +1.004 mm). An overall 6.89% of sites were active; individual patients' means ranged from 0-28.9%. Mean pocket depth (PD) showed minimal change over the study period (-0.033 mm) thus suggesting that most if not all the AL was accompained by concomitant gingival recession. Smokers exhibited greater AL and radiographic BL compared to non-smokers. Likewise, patients' cotinine level showed direct correlation with outcomes of progressive periodontal breakdown. Past severity of periodontal involvement, as reflected in the patients baseline PD, AL and crestal bone height, showed good correlation

  19. Indicadores precoces da dislexia de desenvolvimento: um estudo longitudinal || Early indicators of dyslexia: a longitudinal study

    Directory of Open Access Journals (Sweden)

    Anabela Carvalho

    2017-12-01

    Full Text Available A dislexia do desenvolvimento é frequentemente diagnosticada quando os problemas na aprendizagem da leitura já afetaram negativamente outras áreas académicas e até o bem-estar emocional. A pesquisa internacional aponta para a existência de alguns preditores desta perturbação da aprendizagem, permitindo uma intervenção atempada e preventiva. No entanto, as diferenças relativas ao código ortográfico do Português Europeu não nos permitem tirar ilações de estudos realizados noutros contextos linguísticos. Com este problema em mente, desenvolvemos um estudo longitudinal que pretende destacar os preditores da dislexia em crianças portuguesas. A investigação seguiu um plano longitudinal ao longo de três anos e os resultados obtidos junto de uma amostra de 200 crianças permitem identificar a existência de poder preditivo em duas variáveis: no conhecimento que a criança tem do nome das letras e no seu desempenho em tarefas de fluência verbal, mostrando a influência que os fatores relativos às dificuldades na aquisição do princípio alfabético e no acesso ao léxico terão na manifestação posterior de problemas na aquisição da leitura.

  20. A longitudinal study of maternal attachment and infant developmental outcomes.

    Science.gov (United States)

    Alhusen, Jeanne L; Hayat, Matthew J; Gross, Deborah

    2013-12-01

    Extant research has demonstrated that compared to adults with insecure attachment styles, more securely attached parents tend to be more responsive, sensitive, and involved parents, resulting in improved outcomes for their children. Less studied is the influence of a mother's attachment style on her attachment to her unborn child during pregnancy and the consequent developmental outcomes of the child during early childhood. Thus, the aim of this prospective longitudinal study was to examine the relationship between maternal-fetal attachment (MFA) during pregnancy and infant and toddler outcomes and the role of mothers' attachment style on early childhood developmental outcomes in an economically disadvantaged sample of women and their children. Gamma regression modeling demonstrated that an avoidant maternal attachment style (b = .98, 95 % CI [.97, .98], p attachment styles and greater depressive symptomatology were more likely to have children demonstrating early childhood developmental delays than those women with less avoidant attachment styles and less depressive symptomatology. Furthermore, women reporting higher MFA during pregnancy had more secure attachment styles, and their children had more optimal early childhood development than those women reporting lower MFA and less secure attachment styles. Findings have implications for enhancing early intervention programs aimed at improving maternal and childhood outcomes. An earlier identification of disruptions in attachment may be beneficial in tailoring interventions focused on the mother-child dyad.

  1. Childhood predictors of adult adiposity: findings from a longitudinal study.

    Science.gov (United States)

    McLeod, Geraldine Fh; Fergusson, David M; Horwood, L John; Boden, Joseph M; Carter, Frances A

    2018-03-23

    The increasing prevalence of overweight and obesity has become a key challenge for New Zealand. The purpose of the present study was to examine childhood risk factors for adult adiposity in a longitudinal birth cohort. Data were gathered from the Christchurch Health and Development Study (CHDS), a birth cohort of 1,265 children born in Christchurch in 1977. Associations were examined between socio-demographic background, perinatal factors, infant and child characteristics, family functioning/child maltreatment and adiposity at ages 30 and 35 years. Adiposity was assessed using body mass index scores. At ages 30 and 35, approximately one-third of cohort members were overweight and one-fifth were obese. Generalised estimating equation models showed that statistically significant (p<.05) predictors of later adiposity and overweight/obesity were: male gender, being born into a single-parent family, having parents with larger body size, higher early infant growth, limited or no breastfeeding, lower levels of cognitive ability and exposure to severe sexual abuse. Overweight and obesity was associated with social and family background, biological endowment, cognitive ability and childhood adversity factors. These findings may assist in the development of structured adiposity intervention programmes in conjunction with established community organisations specialising in child and family health.

  2. Interpersonal social responsibility model of service learning: A longitudinal study.

    Science.gov (United States)

    Lahav, Orit; Daniely, Noa; Yalon-Chamovitz, Shira

    2018-01-01

    Service-learning (SL) is commonly used in Occupational Therapy (OT) programs worldwide as a community placement educational strategy. However, most SL models are not clearly defined in terms of both methodology and learning outcomes. This longitudinal study explores a structured model of Service-Learning (Interpersonal Social Responsibility-Service Learning: ISR-SL) aimed towards the development of professional identity among OT students. Based on OT students experiences from the end of the course through later stages as mature students and professionals. A qualitative research design was used to explore the perceptions and experiences of 150 first, second, and third-year OT students and graduates who have participated in ISR-SL during their first academic year. Our findings suggest that the structured, long-term relationship with a person with a disability in the natural environment, which is the core of the ISR-SL, allowed students to develop a professional identity based on seeing the person as a whole and recognizing his/her centrality in the therapeutic relationship. This study suggests ISR-SL as future direction or next step for implementing SL in OT and other healthcare disciplines programs.

  3. Cardiovascular Health and Arterial Stiffness: The Maine Syracuse Longitudinal Study

    Science.gov (United States)

    Crichton, Georgina E; Elias, Merrill F; Robbins, Michael A

    2014-01-01

    Ideal cardiovascular health is a recently defined construct by the American Heart Association (AHA) to promote cardiovascular disease reduction. Arterial stiffness is a major risk factor for cardiovascular disease. The extent to which the presence of multiple prevalent cardiovascular risk factors and health behaviors is associated with arterial stiffness is unknown. The aim of this study was to examine the association between the AHA construct of cardiovascular health and arterial stiffness, as indexed by pulse wave velocity and pulse pressure. The AHA health metrics, comprising of four health behaviors (smoking, body mass index, physical activity, and diet) and three health factors (total cholesterol, blood pressure, and fasting plasma glucose) were evaluated among 505 participants in the Maine-Syracuse Longitudinal Study. Outcome measures were carotid-femoral pulse wave velocity (PWV) and pulse pressure measured at 4 to 5-year follow-up. Better cardiovascular health, comprising both health factors and behaviors, was associated with lower arterial stiffness, as indexed by pulse wave velocity and pulse pressure. Those with at least five health metrics at ideal levels had significantly lower PWV (9.8 m/s) than those with two or less ideal health metrics (11.7 m/s) (P<0.001). This finding remained with the addition of demographic and PWV-related variables (P=0.004). PMID:24384629

  4. Intellectual development in Noonan syndrome: a longitudinal study.

    Science.gov (United States)

    Roelofs, Renée L; Janssen, Nikki; Wingbermühle, Ellen; Kessels, Roy P C; Egger, Jos I M

    2016-07-01

    Although cognitive impairments in adults with Noonan syndrome seem to be limited to a low-average intelligence and slower processing speed, studies in children with Noonan syndrome have demonstrated more extensive cognitive problems. These include deficits in language skills, memory, attention, and executive functioning. This longitudinal study is the first to investigate intellectual development in a group of individuals with Noonan syndrome. Sixteen patients with Noonan syndrome underwent intelligence assessment both in childhood and in adulthood, using Wechsler's intelligence scales. IQ scores and Wechsler standard scores achieved in childhood and adulthood were compared. Subsequently, verbal and performance IQ in childhood were used as predictors for adult IQ and index scores. Compared with childhood scores, adult full-scale IQ and performance IQ significantly increased. Adult performance IQ was higher than verbal IQ. Childhood performance IQ and verbal IQ together predicted all adult IQ and index scores, except for the processing speed index. Childhood IQ was a significant predictor of adult intelligence in patients with Noonan syndrome. Performance IQ advanced to a normal level in adulthood, while verbal IQ did not develop proportionately, resulting in a discrepancy between adult performance IQ and verbal IQ. This finding could suggest a delay in the development of executive functioning in patients with Noonan syndrome, which seems to be outgrown in adulthood.

  5. Whole grain intake: The Baltimore Longitudinal Study of Aging.

    Science.gov (United States)

    Maras, Janice E; Newby, P K; Bakun, Peter J; Ferrucci, Luigi; Tucker, Katherine L

    2009-02-01

    Our objective was to identify major dietary sources of whole grains and to describe the construction of a database of whole grain content of foods. Dietary information was collected with 7-d food records from men and women in the Baltimore Longitudinal Study of Aging, mean age 62.1 +/- 16.0 years, who participated in the dietary assessment portion of the study (n = 1516), and estimates of whole grain intake were obtained from a newly developed database. The Pyramid Servings database and 1994-1996 Continuing Survey of Food Intakes by Individuals (CSFII) recipe ingredients database were then used to calculate both servings and gram weights of whole grain intakes. Mean intakes of whole grains, refined grains, and total grains, as well as frequency of intake for major whole grain food groups and whole grain content for each group, were calculated. Top contributors of whole grains were ready-to-eat breakfast cereals (made with whole grain as well as bran), hot breakfast cereals (made with whole grain), multi-grain bread, and whole wheat bread. While more research is needed to better understand the benefits of whole grains, the development of research tools, including databases to accurately assess whole grain intake, is a critical step in completing such research.

  6. From prenatal anxiety to parenting stress: a longitudinal study.

    Science.gov (United States)

    Huizink, A C; Menting, B; De Moor, M H M; Verhage, M L; Kunseler, F C; Schuengel, C; Oosterman, M

    2017-10-01

    The objective of this study was to explore how maternal mood during pregnancy, i.e., general anxiety, pregnancy-specific anxiety, and depression predicted parenting stress 3 months after giving birth, thereby shaping the child's early postnatal environmental circumstances. To this end, data were used from 1073 women participating in the Dutch longitudinal cohort Generations 2 , which studies first-time pregnant mothers during pregnancy and across the transition to parenthood. Women filled out the State Trait Anxiety Inventory (STAI), Pregnancy-Related Anxiety Questionnaire-revised (PRAQ-R), and Beck Depression Index (BDI) three times during pregnancy: at 12, 22, and 32 weeks gestational age. Three months postpartum, a parenting stress questionnaire was filled out yielding seven different parenting constructs. Latent scores were computed for each of the repeatedly measured maternal mood variables with Mplus and parenting stress constructs were simultaneously regressed on these latent scores. Results showed that trait anxiety and pregnancy-specific anxiety were uniquely related to almost all parenting stress constructs, taking depression into account. Early prevention and intervention to reduce maternal anxiety in pregnancy could hold the key for a more advantageous trajectory of early postnatal parenting.

  7. Race, ideology, and the tea party: a longitudinal study.

    Directory of Open Access Journals (Sweden)

    Eric D Knowles

    Full Text Available The Tea Party movement, which rose to prominence in the United States after the election of President Barack Obama, provides an ideal context in which to examine the roles of racial concerns and ideology in politics. A three-wave longitudinal study tracked changes in White Americans' self-identification with the Tea Party, racial concerns (prejudice and racial identification, and ideologies (libertarianism and social conservatism over nine months. Latent Growth Modeling (LGM was used to evaluate potential causal relationships between Tea Party identification and these factors. Across time points, racial prejudice was indirectly associated with movement identification through Whites' assertions of national decline. Although initial levels of White identity did not predict change in Tea Party identification, initial levels of Tea Party identification predicted increases in White identity over the study period. Across the three assessments, support for the Tea Party fell among libertarians, but rose among social conservatives. Results are discussed in terms of legitimation theories of prejudice, the "racializing" power of political judgments, and the ideological dynamics of the Tea Party.

  8. Race, Ideology, and the Tea Party: A Longitudinal Study

    Science.gov (United States)

    Knowles, Eric D.; Lowery, Brian S.; Shulman, Elizabeth P.; Schaumberg, Rebecca L.

    2013-01-01

    The Tea Party movement, which rose to prominence in the United States after the election of President Barack Obama, provides an ideal context in which to examine the roles of racial concerns and ideology in politics. A three-wave longitudinal study tracked changes in White Americans’ self-identification with the Tea Party, racial concerns (prejudice and racial identification), and ideologies (libertarianism and social conservatism) over nine months. Latent Growth Modeling (LGM) was used to evaluate potential causal relationships between Tea Party identification and these factors. Across time points, racial prejudice was indirectly associated with movement identification through Whites’ assertions of national decline. Although initial levels of White identity did not predict change in Tea Party identification, initial levels of Tea Party identification predicted increases in White identity over the study period. Across the three assessments, support for the Tea Party fell among libertarians, but rose among social conservatives. Results are discussed in terms of legitimation theories of prejudice, the “racializing” power of political judgments, and the ideological dynamics of the Tea Party. PMID:23825630

  9. Orotracheal intubation and temporomandibular disorder: a longitudinal controlled study

    Directory of Open Access Journals (Sweden)

    Cláudia Branco Battistella

    2016-04-01

    Full Text Available ABSTRACT BACKGROUND AND OBJECTIVES: To determine the incidence of signs and symptoms of temporomandibular disorder in elective surgery patients who underwent orotracheal intubation. METHODS: This was a longitudinal controlled study with two groups. The study group included patients who underwent orotracheal intubation and a control group. We used the American Academy of Orofacial Pain questionnaire to assess the temporomandibular disorder signs and symptoms one-day postoperatively (T1, and the patients' baseline status prior to surgery (T0 was also recorded. The same questionnaire was used after three months (T2. The mouth opening amplitude was measured at T1 and T2. We considered a pvalue of less than 0.05 to be significant. RESULTS: We included 71 patients, with 38 in the study group and 33 in the control. There was no significant difference between the groups in age (study group: 66.0 [52.5-72.0]; control group: 54.0 [47.0-68.0]; p = 0.117 or in their belonging to the female gender (study group: 57.9%; control group: 63.6%; p = 0.621. At T1, there were no statistically significant differences between the groups in the incidence of mouth opening limitation (study group: 23.7% vs. control group: 18.2%;p = 0.570 or in the mouth opening amplitude (study group: 45.0 [40.0-47.0] vs. control group: 46.0 [40.0-51.0];p = 0.278. At T2 we obtained similar findings. There was no significant difference in the affirmative response to all the individual questions in the American Academy of Orofacial Pain questionnaire. CONCLUSIONS: In our population, the incidence of signs and symptoms of temporomandibular disorder of muscular origin was not different between the groups.

  10. Two stage catalytic converter system to reduce exhaust emissions of HC, CO and NO in a motor vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Nagalingam, B; Gopalakrishnan, K V; Murthy, B S

    1978-09-01

    Two-stage catalytic converter system is currently receiving considerable attention as a means to control the primary pollutants, namely, HC, CO and NO in the automobile exhaust. In order to explore the possibility of developing catalysts from indigenous and inexpensive sources of materials, sponge iron for NO reduction and manganese ore pebbles for HC/CO oxidation were tested as candidate-catalysts in an engine dynamometer test bed to study their catalytic activity. The results of these experiments are reported.

  11. Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

    OpenAIRE

    Saed, Mohand O.; Torbati, Amir H.; Nair, Devatha P.; Yakacki, Christopher M.

    2016-01-01

    This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline elastomers (LCEs) with facile control over network structure and programming of an aligned monodomain. Tailored LCE networks were synthesized using routine mixing of commercially available starting materials and pouring monomer solutions into molds to cure. An initial polydomain LCE network is formed via a self-limiting thiol-acrylate Michael-addi...

  12. Accelerated Brain Aging in Schizophrenia: A Longitudinal Pattern Recognition Study.

    Science.gov (United States)

    Schnack, Hugo G; van Haren, Neeltje E M; Nieuwenhuis, Mireille; Hulshoff Pol, Hilleke E; Cahn, Wiepke; Kahn, René S

    2016-06-01

    Despite the multitude of longitudinal neuroimaging studies that have been published, a basic question on the progressive brain loss in schizophrenia remains unaddressed: Does it reflect accelerated aging of the brain, or is it caused by a fundamentally different process? The authors used support vector regression, a supervised machine learning technique, to address this question. In a longitudinal sample of 341 schizophrenia patients and 386 healthy subjects with one or more structural MRI scans (1,197 in total), machine learning algorithms were used to build models to predict the age of the brain and the presence of schizophrenia ("schizophrenia score"), based on the gray matter density maps. Age at baseline ranged from 16 to 67 years, and follow-up scans were acquired between 1 and 13 years after the baseline scan. Differences between brain age and chronological age ("brain age gap") and between schizophrenia score and healthy reference score ("schizophrenia gap") were calculated. Accelerated brain aging was calculated from changes in brain age gap between two consecutive measurements. The age prediction model was validated in an independent sample. In schizophrenia patients, brain age was significantly greater than chronological age at baseline (+3.36 years) and progressively increased during follow-up (+1.24 years in addition to the baseline gap). The acceleration of brain aging was not constant: it decreased from 2.5 years/year just after illness onset to about the normal rate (1 year/year) approximately 5 years after illness onset. The schizophrenia gap also increased during follow-up, but more pronounced variability in brain abnormalities at follow-up rendered this increase nonsignificant. The progressive brain loss in schizophrenia appears to reflect two different processes: one relatively homogeneous, reflecting accelerated aging of the brain and related to various measures of outcome, and a more variable one, possibly reflecting individual variation and

  13. Phase I (or phase II) dose-ranging clinical trials: proposal of a two-stage Bayesian design.

    Science.gov (United States)

    Zohar, Sarah; Chevret, Sylvie

    2003-02-01

    We propose a new design for phase I (or phase II) dose-ranging clinical trials aiming at determining a dose of an experimental treatment to satisfy safety (respectively efficacy) requirements, at treating a sufficiently large number of patients to estimate the toxicity (respectively failure) probability of the dose level with a given reliability, and at stopping the trial early if it is likely that no dose is safe (respectively efficacious). A two-stage design was derived from the Continual Reassessment Method (CRM), with implementation of Bayesian criteria to generate stopping rules. A simulation study was conducted to compare the operating characteristics of the proposed two-stage design to those reached by the traditional CRM. Finally, two applications to real data sets are provided.

  14. Two-stage soil infiltration treatment system for treating ammonium wastewaters of low COD/TN ratios.

    Science.gov (United States)

    Lei, Zhongfang; Wu, Ting; Zhang, Yi; Liu, Xiang; Wan, Chunli; Lee, Duu-Jong; Tay, Joo-Hwa

    2013-01-01

    Soil infiltration treatment (SIT) is ineffective to treat ammonium wastewaters of total nitrogen (TN) > 100 mg l(-1). This study applied a novel two-stage SIT process for effective TN removal from wastewaters of TN>100 mg l(-1) and of chemical oxygen demand (COD)/TN ratio of 3.2-8.6. The wastewater was first fed into the soil column (stage 1) at hydraulic loading rate (HLR) of 0.06 m(3) m(-2) d(-1) for COD removal and total phosphorus (TP) immobilization. Then the effluent from stage 1 was fed individually into four soil columns (stage 2) at 0.02 m(3) m(-2) d(-1) of HLR with different proportions of raw wastewater as additional carbon source. Over the one-year field test, balanced nitrification and denitrification in the two-stage SIT revealed excellent TN removal (>90%) from the tested wastewaters. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. A two-stage optimal planning and design method for combined cooling, heat and power microgrid system

    International Nuclear Information System (INIS)

    Guo, Li; Liu, Wenjian; Cai, Jiejin; Hong, Bowen; Wang, Chengshan

    2013-01-01

    Highlights: • A two-stage optimal method is presented for CCHP microgrid system. • Economic and environmental performance are considered as assessment indicators. • Application case demonstrates its good economic and environmental performance. - Abstract: In this paper, a two-stage optimal planning and design method for combined cooling, heat and power (CCHP) microgrid system was presented. The optimal objective was to simultaneously minimize the total net present cost and carbon dioxide emission in life circle. On the first stage, multi-objective genetic algorithm based on non-dominated sorting genetic algorithm-II (NSGA-II) was applied to solve the optimal design problem including the optimization of equipment type and capacity. On the second stage, mixed-integer linear programming (MILP) algorithm was used to solve the optimal dispatch problem. The approach was applied to a typical CCHP microgrid system in a hospital as a case study, and the effectiveness of the proposed method was verified

  16. Longitudinal study of leptin levels in chronic hemodialysis patients

    Directory of Open Access Journals (Sweden)

    Averbukh Zhan

    2011-06-01

    Full Text Available Abstract Background The influence of serum leptin levels on nutritional status and survival in chronic hemodialysis patients remained to be elucidated. We conducted a prospective longitudinal study of leptin levels and nutritional parameters to determine whether changes of serum leptin levels modify nutritional status and survival in a cohort of prevalent hemodialysis patients. Methods Leptin, dietary energy and protein intake, biochemical markers of nutrition and body composition (anthropometry and bioimpedance analysis were measured at baseline and at 6, 12, 18 and 24 months following enrollment, in 101 prevalent hemodialysis patients (37% women with a mean age of 64.6 ± 11.5 years. Observation of this cohort was continued over 2 additional years. Changes in repeated measures were evaluated, with adjustment for baseline differences in demographic and clinical parameters. Results Significant reduction of leptin levels with time were observed (linear estimate: -2.5010 ± 0.57 ng/ml/2y; p Conclusions Thus leptin levels reflect fat mass depots, rather than independently contributing to uremic anorexia or modifying nutritional status and/or survival in chronic hemodialysis patients. The importance of such information is high if leptin is contemplated as a potential therapeutic target in hemodialysis patients.

  17. Spiritual stress and coping model of divorce: a longitudinal study.

    Science.gov (United States)

    Krumrei, Elizabeth J; Mahoney, Annette; Pargament, Kenneth I

    2011-12-01

    This study represents the first longitudinal effort to use a spiritual stress and coping model to predict adults' psychosocial adjustment following divorce. A community sample of 89 participants completed measures at the time of their divorce and 1 year later. Though the sample endorsed slightly lower levels of religiosity than the general U.S. population, most reported spiritual appraisals and positive and negative religious coping tied to divorce. Hierarchical regression analyses controlling general religiousness and nonreligious forms of coping indicated that (a) appraising divorce as a sacred loss or desecration at the time it occurred predicted more depressive symptoms and dysfunctional conflict tactics with the ex-spouse 1 year later; (b) positive religious coping reported about the year following divorce predicted greater posttraumatic growth 1 year after divorce; and (c) negative religious coping reported about the year following divorce predicted more depressive symptoms 1 year after the divorce. Bootstrapping mediation analyses indicated that negative religious coping fully mediated links between appraising the divorce as a sacred loss or desecration at the time it occurred and depressive symptoms 1 year later. In addition, moderation analyses revealed that negative religious coping is more strongly associated with depressive symptoms among those who form high versus low appraisals of their divorce as a sacred loss or desecration. These findings are relevant to divorce education and intervention provided by professionals in legal, family, mental health, and clerical roles. Implications are discussed for clinical and counseling psychology and religious communities.

  18. Mild traumatic brain injury and fatigue: a prospective longitudinal study.

    Science.gov (United States)

    Norrie, Joan; Heitger, Marcus; Leathem, Janet; Anderson, Tim; Jones, Richard; Flett, Ross

    2010-01-01

    To examine fatigue prevalence, severity, predictors and co-variates over 6 months post-mild traumatic brain injury (MTBI). Longitudinal prospective study including 263 adults with MTBI. Participants completed the Fatigue Severity Scale (FSS), Rivermead Post-concussion Symptoms Questionnaire (RPSQ), Hospital Anxiety and Depression Scale (HADS) and the Short Form 36 Health Survey-Version 2 (SF-36v2). Complete data were available for 159 participants. Key measures; prevalence--RPSQ Item 6: severity--FSS. The effect of time on fatigue prevalence and severity was examined using ANOVA. Multiple regression analysis identified statistically significant covariates. Post-MTBI fatigue prevalence was 68%, 38% and 34% at 1 week, 3 and 6 months, respectively. There was a strong effect for time over the first 3 months and moderate-to-high correlations between fatigue prevalence and severity. Early fatigue strongly predicted later fatigue; depression, but not anxiety was a predictor. Fatigue was seen as laziness by family or friends in 30% of cases. Post-MTBI fatigue is a persistent post-concussion symptom, exacerbated by depression but not anxiety. It diminishes in the first 3 months and then becomes relatively stable, suggesting the optimum intervention placement is at 3 months or more post-MTBI.

  19. Religiousness, spiritual seeking, and personality: findings from a longitudinal study.

    Science.gov (United States)

    Wink, Paul; Ciciolla, Lucia; Dillon, Michele; Tracy, Allison

    2007-10-01

    The hypothesis that personality characteristics in adolescence can be used to predict religiousness and spiritual seeking in late adulthood was tested using a structural equation modeling framework to estimate cross-lagged and autoregressive effects in a two-wave panel design. The sample consisted of 209 men and women participants in the Berkeley Guidance and Oakland Growth studies. In late adulthood, religiousness was positively related to Conscientiousness and Agreeableness, and spiritual seeking was related to Openness to Experience. Longitudinal models indicated that Conscientiousness in adolescence significantly predicted religiousness in late adulthood above and beyond adolescent religiousness. Similarly, Openness in adolescence predicted spiritual seeking in late adulthood. The converse effect, adolescent religiousness to personality in late adulthood, was not significant in either model. Among women, adolescent Agreeableness predicted late-life religiousness and adolescent religiousness predicted late-life Agreeableness; both these effects were absent among men. Adolescent personality appears to shape late-life religiousness and spiritual seeking independent of early religious socialization.

  20. Predictors of workplace violence among ambulance personnel: a longitudinal study.

    Science.gov (United States)

    van der Velden, Peter G; Bosmans, Mark W G; van der Meulen, Erik

    2016-04-01

    To examine predictors of repeated confrontations with workplace violence among ambulance personnel, the proportion of exposure to potentially traumatic events that are aggression-related and to what extent personnel was able to prevent escalations. Although previous research assessed the prevalences among this group, little is known about predictors, to what extent PTE's are WPV-related and their abilities to prevent escalations. A longitudinal study with a 6 months' time interval ( N  =   103). At T1 demographics, workplace violence and potentially traumatic events in the past year, mental health, personality, handling of rules, coping and social organizational stressors were assessed. Confrontations with aggression were also examined at T2. Multivariate logistic regression analyses showed that only problems with superiors independently predicted repeated verbal aggression and that only the (absence of the) ability to compromise very easily predicted repeatedly being on guard and repeatedly confronted with any form of aggression. Due to very low prevalences, we could not examine predictors of repeated confrontations with physical aggression ( N  =   5) and serious threat ( N  =   7). A large majority reported that in most workplace violence cases they could prevent further escalations. About 2% reported a potentially traumatic event in the year before T1 that was WPV related and perceived as very stressful.

  1. Executive function influences sedentary behavior: A longitudinal study

    Directory of Open Access Journals (Sweden)

    Paul D. Loprinzi

    2016-10-01

    Full Text Available Background: No study has evaluated the effects of executive function on follow-up sedentary behavior, which was this study’s purpose. Methods: A longitudinal design was employed among 18 young adult college students (Mage = 23.7 years; 88.9% female. Accelerometer-determined sedentary behavior and physical activity, along with executive function, were assessed at baseline. Approximately 8 weeks later, re-assessment of accelerometer-determined sedentary behavior and physical activity occurred. Executive function was assessed using the Parametric Go/No-Go (PGNG computer task. From this, 2 primary executive function outcome parameters were evaluated, including the Simple Rule and Repeating Rule. Results: After adjusting for baseline sedentary behavior, age, gender, body mass index and baseline moderate-to-vigorous physical activity (MVPA, for every 25% increase in the number of correctly identified targets for the Repeating rule at the baseline assessment, participants engaged in 91.8 fewer minutes of sedentary behavior at the follow-up assessment (β = -91.8; 95% CI: -173.5, -10.0; P = 0.03. Results were unchanged when also adjusting for total baseline or follow-up physical activity. Conclusion: Greater executive function is associated with less follow-up sedentary behavior.

  2. Shifting accountability: a longitudinal qualitative study of diabetes causation accounts.

    Science.gov (United States)

    Lawton, Julia; Peel, Elizabeth; Parry, Odette; Douglas, Margaret

    2008-07-01

    We undertook a longitudinal qualitative study involving of 20 patients from Scotland who had type 2 diabetes. We looked at their perceptions and understandings of why they had developed diabetes and how, and why, their causation accounts had changed or remained stable over time. Respondents, all of whom were white, were interviewed four times over a 4-year period (at baseline, 6, 12 and 48 months). Their causation accounts often shifted, sometimes subtly, sometimes radically, over the 4 years. The experiential dimensions of living with, observing, and managing their disease over time were central to understanding the continuities and changes we observed. We also highlight how, through a process of removing, adding and/or de-emphasising explanatory factors, causation accounts could be used as "resources" to justify or enable present treatment choices. We use our work to support critiques of social cognition theories, with their emphasis upon beliefs being antecedent to behaviours. We also provide reflections upon the implications of our findings for qualitative research designs and sampling strategies.

  3. Two-stage categorization in brand extension evaluation: electrophysiological time course evidence.

    Directory of Open Access Journals (Sweden)

    Qingguo Ma

    Full Text Available A brand name can be considered a mental category. Similarity-based categorization theory has been used to explain how consumers judge a new product as a member of a known brand, a process called brand extension evaluation. This study was an event-related potential study conducted in two experiments. The study found a two-stage categorization process reflected by the P2 and N400 components in brand extension evaluation. In experiment 1, a prime-probe paradigm was presented in a pair consisting of a brand name and a product name in three conditions, i.e., in-category extension, similar-category extension, and out-of-category extension. Although the task was unrelated to brand extension evaluation, P2 distinguished out-of-category extensions from similar-category and in-category ones, and N400 distinguished similar-category extensions from in-category ones. In experiment 2, a prime-probe paradigm with a related task was used, in which product names included subcategory and major-category product names. The N400 elicited by subcategory products was more significantly negative than that elicited by major-category products, with no salient difference in P2. We speculated that P2 could reflect the early low-level and similarity-based processing in the first stage, whereas N400 could reflect the late analytic and category-based processing in the second stage.

  4. The Timing of Maternal Depressive Symptoms and Child Cognitive Development: A Longitudinal Study

    Science.gov (United States)

    Evans, Jonathan; Melotti, Roberto; Heron, Jon; Ramchandani, Paul; Wiles, Nicola; Murray, Lynne; Stein, Alan

    2012-01-01

    Background: Maternal depression is known to be associated with impairments in child cognitive development, although the effect of timing of exposure to maternal depression is unclear. Methods: Data collected for the Avon Longitudinal Study of Parents and Children, a longitudinal study beginning in pregnancy, included self-report measures of…

  5. Transition overtime in household latrine use in rural Bangladesh: a longitudinal cohort study

    Science.gov (United States)

    2014-01-01

    Background In a low-income country like Bangladesh, where the poverty rate is higher in rural compared to urban areas, the consistent use of sanitary latrines over time is a challenge. To address this issue, the Water, Sanitation, and Hygiene (WASH) program of the Bangladesh Rural Advancement Committee (BRAC) was devised to improve health of the rural poor through enhanced sanitation services, such as by providing loans or education. Sanitary latrine use in households and changes over time were assessed in this study. Methods This was a longitudinal cohort study of the baseline, midline, and end line status of the WASH project. Households assessed in all three rounds of surveys (26,404 in each survey) were included in the analysis. Thirty thousand households from 50 upazilas (sub-districts) were selected in two stages: i) thirty villages were selected from each of the 50 upazilas by cluster sampling, and ii) twenty households were chosen systematically from each selected village. A female member capable of providing household-level information was interviewed from each house using the pre-tested questionnaire. Spot observations of some components were made to assess the quality of sanitary latrine use. The adjusted log-binomial regression was performed and risk ratios with 95% confidence intervals were estimated for sanitary latrine use. Data were analyzed using Statistical Package for the Social Sciences (SPSS) and Stata software. Results The use of sanitary latrines by households increased significantly from the baseline (31.7%) to midline (41.5%) and end line (57.4%) assessment points. The proportion of physically verified clean latrines increased significantly from 33.4% at baseline to 50.8% at the midline and 53.3% at the end line. Analysis of changes in latrine-use showed that 73.3% of the baseline latrine-using households continued to do so at the end line, while the rest switched to unsanitary practices. Households with better socioeconomic status were more

  6. Psychological characteristics of chronic depression: a longitudinal cohort study.

    Science.gov (United States)

    Wiersma, Jenneke E; van Oppen, Patricia; van Schaik, Digna J F; van der Does, A J Willem; Beekman, Aartjan T F; Penninx, Brenda W J H

    2011-03-01

    Few studies have investigated the importance of psychological characteristics for chronicity of depression. Knowledge about psychological differences between chronically depressed persons and nonchronically depressed persons may help to improve treatment of chronic depression. This is the first study to simultaneously compare in large samples various psychological characteristics between chronically depressed and nonchronically depressed adults. Baseline data were drawn from the Netherlands Study of Depression and Anxiety (NESDA), an ongoing longitudinal cohort study aimed at examining the long-term course of depressive and anxiety disorders in different health care settings and phases of illness. Participants were aged 18 to 65 years at the baseline assessment in 2004-2007 and had a current diagnosis of DSM-IV major depressive disorder (N = 1,002). Chronicity of depression was defined as being depressed for 24 months or more in the past 4 to 5 years. The chronicity criterion was fulfilled by 31% (n = 312). The NEO Five-Factor Inventory measured the 5 personality domains, the Leiden Index of Depression Sensitivity-Revised was used to measure cognitive reactivity (eg, hopelessness, rumination), and the Mastery Scale measured external locus of control. Compared to the nonchronically depressed persons, the chronically depressed persons reported significantly higher levels of neuroticism (OR = 1.81; 95% CI, 1.55-2.12; P testing these variables multivariably, the odds of chronic depression were significantly increased among those with low extraversion (OR = 0.73; 95% CI, 0.61-0.88; P = .001), high rumination (OR = 1.24; 95% CI, 1.01-1.53; P = .04), and high external locus of control (OR = 1.48; 95% CI, 1.21-1.80; P psychological characteristics for chronicity of depression. These findings provide suggestions for more specific interventions, focused on extraversion, rumination, and external locus of control, in the treatment of chronic depression. © Copyright 2011

  7. Rationales, design and recruitment for the Elfe longitudinal study

    Directory of Open Access Journals (Sweden)

    Salines Georges

    2009-09-01

    Full Text Available Abstract Background Many factors act simultaneously in childhood to influence health status, life chances and well being, including pre-birth influences, the environmental pollutants of early life, health status but also the social influences of family and school. A cohort study is needed to disentangle these influences and explore attribution. Methods Elfe will be a nationally representative cohort of 20 000 children followed from birth to adulthood using a multidisciplinary approach. The cohort will be based on the INSEE Permanent Demographic Panel (EDP established using census data and civil records. The sample size has been defined in order to match the representativeness criteria and to obtain some prevalence estimation, but also to address the research area of low exposure/rare effects. The cohort will be based on repeated surveys by face to face or phone interview (at birth and each year as well as medical interview (at 2 years and examination (at 6 years. Furthermore, biological samples will be taken at birth to evaluate the foetal exposition to toxic substances, environmental sensors will be placed in the child's homes. Pilot studies have been initiated in 2007 (500 children with an overall acceptance rate of 55% and are currently under progress, the 2-year survey being carried out in October this year. Discussion The longitudinal study will provide a unique source of data to analyse the development of children in their environment, to study the various factors interacting throughout the life course up to adulthood and to determine the impact of childhood experience on the individual's physical, psychological, social and professional development.

  8. Adaptive Urban Stormwater Management Using a Two-stage Stochastic Optimization Model

    Science.gov (United States)

    Hung, F.; Hobbs, B. F.; McGarity, A. E.

    2014-12-01

    In many older cities, stormwater results in combined sewer overflows (CSOs) and consequent water quality impairments. Because of the expense of traditional approaches for controlling CSOs, cities are considering the use of green infrastructure (GI) to reduce runoff and pollutants. Examples of GI include tree trenches, rain gardens, green roofs, and rain barrels. However, the cost and effectiveness of GI are uncertain, especially at the watershed scale. We present a two-stage stochastic extension of the Stormwater Investment Strategy Evaluation (StormWISE) model (A. McGarity, JWRPM, 2012, 111-24) to explicitly model and optimize these uncertainties in an adaptive management framework. A two-stage model represents the immediate commitment of resources ("here & now") followed by later investment and adaptation decisions ("wait & see"). A case study is presented for Philadelphia, which intends to extensively deploy GI over the next two decades (PWD, "Green City, Clean Water - Implementation and Adaptive Management Plan," 2011). After first-stage decisions are made, the model updates the stochastic objective and constraints (learning). We model two types of "learning" about GI cost and performance. One assumes that learning occurs over time, is automatic, and does not depend on what has been done in stage one (basic model). The other considers learning resulting from active experimentation and learning-by-doing (advanced model). Both require expert probability elicitations, and learning from research and monitoring is modelled by Bayesian updating (as in S. Jacobi et al., JWRPM, 2013, 534-43). The model allocates limited financial resources to GI investments over time to achieve multiple objectives with a given reliability. Objectives include minimizing construction and O&M costs; achieving nutrient, sediment, and runoff volume targets; and community concerns, such as aesthetics, CO2 emissions, heat islands, and recreational values. CVaR (Conditional Value at Risk) and

  9. Combined two-stage xanthate processes for the treatment of copper-containing wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Y.K. [Department of Safety Health and Environmental Engineering, Central Taiwan University of Sciences and Technology, Taichung (Taiwan); Leu, M.H. [Department of Environmental Engineering, Kun Shan University of Technology, Yung-Kang City (Taiwan); Chang, J.E.; Lin, T.F.; Chen, T.C. [Department of Environmental Engineering, National Cheng Kung University, Tainan City (Taiwan); Chiang, L.C.; Shih, P.H. [Department of Environmental Engineering and Science, Fooyin University, Kaohsiung County (Taiwan)

    2007-02-15

    Heavy metal removal is mainly conducted by adjusting the wastewater pH to form metal hydroxide precipitates. However, in recent years, the xanthate process with a high metal removal efficiency, attracted attention due to its use of sorption/desorption of heavy metals from aqueous solutions. In this study, two kinds of agricultural xanthates, insoluble peanut-shell xanthate (IPX) and insoluble starch xanthate (ISX), were used as sorbents to treat the copper-containing wastewater (Cu concentration from 50 to 1,000 mg/L). The experimental results showed that the maximum Cu removal efficiency by IPX was 93.5 % in the case of high Cu concentrations, whereby 81.1 % of copper could rapidly be removed within one minute. Moreover, copper-containing wastewater could also be treated by ISX over a wide range (50 to 1,000 mg/L) to a level that meets the Taiwan EPA's effluent regulations (3 mg/L) within 20 minutes. Whereas IPX had a maximum binding capacity for copper of 185 mg/g IPX, the capacity for ISX was 120 mg/g ISX. IPX is cheaper than ISX, and has the benefits of a rapid reaction and a high copper binding capacity, however, it exhibits a lower copper removal efficiency. A sequential IPX and ISX treatment (i.e., two-stage xanthate processes) could therefore be an excellent alternative. The results obtained using the two-stage xanthate process revealed an effective copper treatment. The effluent (C{sub e}) was below 0.6 mg/L, compared to the influent (C{sub 0}) of 1,001 mg/L at pH = 4 and a dilution rate of 0.6 h{sup -1}. Furthermore, the Cu-ISX complex formed could meet the Taiwan TCLP regulations, and be classified as non-hazardous waste. The xanthatilization of agricultural wastes offers a comprehensive strategy for solving both agricultural waste disposal and metal-containing wastewater treatment problems. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  10. A farm-scale pilot plant for biohydrogen and biomethane production by two-stage fermentation

    Directory of Open Access Journals (Sweden)

    R. Oberti

    2013-09-01

    Full Text Available Hydrogen is considered one of the possible main energy carriers for the future, thanks to its unique environmental properties. Indeed, its energy content (120 MJ/kg can be exploited virtually without emitting any exhaust in the atmosphere except for water. Renewable production of hydrogen can be obtained through common biological processes on which relies anaerobic digestion, a well-established technology in use at farm-scale for treating different biomass and residues. Despite two-stage hydrogen and methane producing fermentation is a simple variant of the traditional anaerobic digestion, it is a relatively new approach mainly studied at laboratory scale. It is based on biomass fermentation in two separate, seuqential stages, each maintaining conditions optimized to promote specific bacterial consortia: in the first acidophilic reactorhydrogen is produced production, while volatile fatty acids-rich effluent is sent to the second reactor where traditional methane rich biogas production is accomplished. A two-stage pilot-scale plant was designed, manufactured and installed at the experimental farm of the University of Milano and operated using a biomass mixture of livestock effluents mixed with sugar/starch-rich residues (rotten fruits and potatoes and expired fruit juices, afeedstock mixture based on waste biomasses directly available in the rural area where plant is installed. The hydrogenic and the methanogenic reactors, both CSTR type, had a total volume of 0.7m3 and 3.8 m3 respectively, and were operated in thermophilic conditions (55 2 °C without any external pH control, and were fully automated. After a brief description of the requirements of the system, this contribution gives a detailed description of its components and of engineering solutions to the problems encountered during the plant realization and start-up. The paper also discusses the results obtained in a first experimental run which lead to production in the range of previous

  11. Two-stage laparoscopic approaches for high anorectal malformation: transumbilical colostomy and anorectoplasty.

    Science.gov (United States)

    Yang, Li; Tang, Shao-Tao; Li, Shuai; Aubdoollah, T H; Cao, Guo-Qing; Lei, Hai-Yan; Wang, Xin-Xing

    2014-11-01

    Trans-umbilical colostomy (TUC) has been previously created in patients with Hirschsprung's disease and intermediate anorectal malformation (ARM), but not in patients with high-ARM. The purposes of this study were to assess the feasibility, safety, complications and cosmetic results of TUC in a divided fashion, and subsequently stoma closure and laparoscopic assisted anorectoplasty (LAARP) were simultaneously completed by using the colostomy site for a laparoscopic port in high-ARM patients. Twenty male patients with high-ARMs were chosen for this two-stage procedure. The first-stage consisted of creating the TUC in double-barreled fashion colostomy with a high chimney at the umbilicus, and the loop was divided at the same time, in such a way that the two diverting ends were located at the umbilical incision with the distal end half closed and slightly higher than proximal end. In the second-stage, 3 to 7 months later, the stoma was closed through a peristomal skin incision followed by end-to-end anastomosis and simultaneously LAARP was performed by placing a laparoscopic port at the umbilicus, which was previously the colonostomy site. Umbilical wound closure was performed in a semi-opened fashion to create a deep umbilicus. TUC and LAARP were successfully performed in 20 patients. Four cases with bladder neck fistulas and 16 cases with prostatic urethra fistulas were found. Postoperative complications were rectal mucosal prolapsed in three cases, anal stricture in two cases and wound dehiscence in one case. Neither umbilical ring narrowing, parastomal hernia nor obstructive symptoms was observed. Neither umbilical nor perineal wound infection was observed. Stoma care was easily carried-out by attaching stoma bag. Healing of umbilical wounds after the second-stage was excellent. Early functional stooling outcome were satisfactory. The umbilicus may be an alternative stoma site for double-barreled colostomy in high-ARM patients. The two-stage laparoscopic

  12. Assessing vanadium and arsenic exposure of people living near a petrochemical complex with two-stage dispersion models

    International Nuclear Information System (INIS)

    Chio, Chia-Pin; Yuan, Tzu-Hsuen; Shie, Ruei-Hao; Chan, Chang-Chuan

    2014-01-01

    Highlights: • Two-stage dispersion models can estimate exposures to hazardous air pollutants. • Spatial distribution of V levels is derived for sources without known emission rates. • A distance-to-source gradient is found for V levels from a petrochemical complex. • Two-stage dispersion is useful for modeling air pollution in resource-limited areas. - Abstract: The goal of this study is to demonstrate that it is possible to construct a two-stage dispersion model empirically for the purpose of estimating air pollution levels in the vicinity of petrochemical plants. We studied oil refineries and coal-fired power plants in the No. 6 Naphtha Cracking Complex, an area of 2,603-ha situated on the central west coast of Taiwan. The pollutants targeted were vanadium (V) from oil refineries and arsenic (As) from coal-fired power plants. We applied a backward fitting method to determine emission rates of V and As, with 192 PM 10 filters originally collected between 2009 and 2012. Our first-stage model estimated emission rates of V and As (median and 95% confidence intervals at 0.0202 (0.0040–0.1063) and 0.1368 (0.0398–0.4782) g/s, respectively. In our second stage model, the predicted zone-average concentrations showed a strong correlation with V, but a poor correlation with As. Our findings show that two-stage dispersion models are relatively precise for estimating V levels at residents’ addresses near the petrochemical complex, but they did not work as well for As levels. In conclusion, our model-based approach can be widely used for modeling exposure to air pollution from industrial areas in countries with limited resources

  13. Combined effects of channel curvature and rotor configuration on the performance of two-stage viscous micropumps

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Dong Jin [Yeungnam University, Gyeongsan (Korea, Republic of)

    2017-06-15

    The combined effects of channel curvature and rotor configuration on the performance of two-stage viscous micropumps were studied numerically. The Navier-Stokes equations were simulated to investigate the performance of two-stage micropumps. The performance of two-stage micropumps was studied in terms of the dimensionless mass flow rate and dimensionless driving power. Four different rotor configurations were designed by changing placement of two rotors inside a microchannel: Two aligned and two staggered configurations. The aligned rotor configuration of type 1 is to place the two rotors along the convex wall, while type 2 is to place them along the concave wall. Numerical results show that the rotor configuration plays a significant role in the performance of two-stage micropumps. The chan-nel curvature acts in a different way according to the rotor configuration. The mass flow rate of aligned rotor configuration of type 1 is greatly improved by the channel curvature, while it diminishes the mass flow rate of type 2. The maximum mass flow rate for the aligned rotor configuration of type 1 is obtained when the two rotors are placed at the junction of the circular and straight sections of the channel. The performance of staggered configurations is negligibly affected by the channel curvature. This characteristics is found due to rotation direction of the rotors. As the two rotors rotate in the opposite direction for the staggered configurations, the flow characteristics in the circular section is little affected by the channel curvature. The circumferential distance between the two rotors can be optimized in terms of the mass flow rate. The optimal value of the circumferential distance is about L = 1.4 for the staggered rotor configurations, and it is almost independent of the channel curvature. As the channel height increases, the circumferential distance becomes less significant for the staggered rotor configurations while it becomes significant for the aligned

  14. A Two-Stage Maximum Entropy Prior of Location Parameter with a Stochastic Multivariate Interval Constraint and Its Properties

    Directory of Open Access Journals (Sweden)

    Hea-Jung Kim

    2016-05-01

    Full Text Available This paper proposes a two-stage maximum entropy prior to elicit uncertainty regarding a multivariate interval constraint of the location parameter of a scale mixture of normal model. Using Shannon’s entropy, this study demonstrates how the prior, obtained by using two stages of a prior hierarchy, appropriately accounts for the information regarding the stochastic constraint and suggests an objective measure of the degree of belief in the stochastic constraint. The study also verifies that the proposed prior plays the role of bridging the gap between the canonical maximum entropy prior of the parameter with no interval constraint and that with a certain multivariate interval constraint. It is shown that the two-stage maximum entropy prior belongs to the family of rectangle screened normal distributions that is conjugate for samples from a normal distribution. Some properties of the prior density, useful for developing a Bayesian inference of the parameter with the stochastic constraint, are provided. We also propose a hierarchical constrained scale mixture of normal model (HCSMN, which uses the prior density to estimate the constrained location parameter of a scale mixture of normal model and demonstrates the scope of its applicability.

  15. Energy production from agricultural residues: High methane yields in pilot-scale two-stage anaerobic digestion

    International Nuclear Information System (INIS)

    Parawira, W.; Read, J.S.; Mattiasson, B.; Bjoernsson, L.

    2008-01-01

    There is a large, unutilised energy potential in agricultural waste fractions. In this pilot-scale study, the efficiency of a simple two-stage anaerobic digestion process was investigated for stabilisation and biomethanation of solid potato waste and sugar beet leaves, both separately and in co-digestion. A good phase separation between hydrolysis/acidification and methanogenesis was achieved, as indicated by the high carbon dioxide production, high volatile fatty acid concentration and low pH in the acidogenic reactors. Digestion of the individual substrates gave gross energy yields of 2.1-3.4 kWh/kg VS in the form of methane. Co-digestion, however, gave up to 60% higher methane yield, indicating that co-digestion resulted in improved methane production due to the positive synergism established in the digestion liquor. The integrity of the methane filters (MFs) was maintained throughout the period of operation, producing biogas with 60-78% methane content. A stable effluent pH showed that the methanogenic reactors had good ability to withstand the variations in load and volatile fatty acid concentrations that occurred in the two-stage process. The results of this pilot-scale study show that the two-stage anaerobic digestion system is suitable for effective conversion of semi-solid agricultural residues as potato waste and sugar beet leaves

  16. Hourly cooling load forecasting using time-indexed ARX models with two-stage weighted least squares regression

    International Nuclear Information System (INIS)

    Guo, Yin; Nazarian, Ehsan; Ko, Jeonghan; Rajurkar, Kamlakar

    2014-01-01

    Highlights: • Developed hourly-indexed ARX models for robust cooling-load forecasting. • Proposed a two-stage weighted least-squares regression approach. • Considered the effect of outliers as well as trend of cooling load and weather patterns. • Included higher order terms and day type patterns in the forecasting models. • Demonstrated better accuracy compared with some ARX and ANN models. - Abstract: This paper presents a robust hourly cooling-load forecasting method based on time-indexed autoregressive with exogenous inputs (ARX) models, in which the coefficients are estimated through a two-stage weighted least squares regression. The prediction method includes a combination of two separate time-indexed ARX models to improve prediction accuracy of the cooling load over different forecasting periods. The two-stage weighted least-squares regression approach in this study is robust to outliers and suitable for fast and adaptive coefficient estimation. The proposed method is tested on a large-scale central cooling system in an academic institution. The numerical case studies show the proposed prediction method performs better than some ANN and ARX forecasting models for the given test data set

  17. Social Strategies during University Studies Predict Early Career Work Burnout and Engagement: 18-Year Longitudinal Study

    Science.gov (United States)

    Salmela-Aro, Katariina; Tolvanen, Asko; Nurmi, Jari-Erik

    2011-01-01

    This longitudinal study spanning 18 years examined the role of social strategies in early career adaptation. The aim was to find out whether individuals' social strategies measured during their university studies had an impact on work burnout and work engagement measured 10-18 years later. A sample of 292 university students completed the SAQ…

  18. A Risk-Based Interval Two-Stage Programming Model for Agricultural System Management under Uncertainty

    Directory of Open Access Journals (Sweden)

    Ye Xu

    2016-01-01

    Full Text Available Nonpoint source (NPS pollution caused by agricultural activities is main reason that water quality in watershed becomes worse, even leading to deterioration. Moreover, pollution control is accompanied with revenue’s fall for agricultural system. How to design and generate a cost-effective and environmentally friendly agricultural production pattern is a critical issue for local managers. In this study, a risk-based interval two-stage programming model (RBITSP was developed. Compared to general ITSP model, significant contribution made by RBITSP model was that it emphasized importance of financial risk under various probabilistic levels, rather than only being concentrated on expected economic benefit, where risk is expressed as the probability of not meeting target profit under each individual scenario realization. This way effectively avoided solutions’ inaccuracy caused by traditional expected objective function and generated a variety of solutions through adjusting weight coefficients, which reflected trade-off between system economy and reliability. A case study of agricultural production management with the Tai Lake watershed was used to demonstrate superiority of proposed model. Obtained results could be a base for designing land-structure adjustment patterns and farmland retirement schemes and realizing balance of system benefit, system-failure risk, and water-body protection.

  19. Two stage enucleation and deflation of a large unicystic ameloblastoma with mural invasion in mandible.

    Science.gov (United States)

    Sasaki, Ryo; Watanabe, Yorikatsu; Ando, Tomohiro; Akizuki, Tanetaka

    2014-06-01

    A treatment for strategy of unicystic ameloblastoma (UA) should be decided by its pathology type including luminal or mural type. Luminal type of UA can be treated only by enucleation alone, but UA with mural invasion should be treated aggressively like conventional ameloblastomas. However, it is difficult to diagnose the subtype of UA by an initial biopsy. There is a possibility that the lesion is an ordinary cyst or keratocystic odontogenic tumor, leading to a possible overtreatment. Therefore, this study performed the enucleation of the cyst wall and deflation at first, and the pathological finding confirmed mural invasion into the cystic wall, leading to the second surgery. The second surgery enucleated scar tissue, bone curettage, and deflation, and was able to contribute to the reduction of the recurrence rate by removing tumor nest in scar tissue or new bone, enhancing new bone formation, and shrinking the mandibular expanding by fenestration. In this study, a large UA with mural invasion including condyle was treated by "two-stage enucleation and deflation" in a 20-year-old patient.

  20. Fleet Planning Decision-Making: Two-Stage Optimization with Slot Purchase

    Directory of Open Access Journals (Sweden)

    Lay Eng Teoh

    2016-01-01

    Full Text Available Essentially, strategic fleet planning is vital for airlines to yield a higher profit margin while providing a desired service frequency to meet stochastic demand. In contrast to most studies that did not consider slot purchase which would affect the service frequency determination of airlines, this paper proposes a novel approach to solve the fleet planning problem subject to various operational constraints. A two-stage fleet planning model is formulated in which the first stage selects the individual operating route that requires slot purchase for network expansions while the second stage, in the form of probabilistic dynamic programming model, determines the quantity and type of aircraft (with the corresponding service frequency to meet the demand profitably. By analyzing an illustrative case study (with 38 international routes, the results show that the incorporation of slot purchase in fleet planning is beneficial to airlines in achieving economic and social sustainability. The developed model is practically viable for airlines not only to provide a better service quality (via a higher service frequency to meet more demand but also to obtain a higher revenue and profit margin, by making an optimal slot purchase and fleet planning decision throughout the long-term planning horizon.

  1. Compressed gas combined single- and two-stage light-gas gun

    Science.gov (United States)

    Lamberson, L. E.; Boettcher, P. A.

    2018-02-01

    With more than 1 trillion artificial objects smaller than 1 μm in low and geostationary Earth orbit, space assets are subject to the constant threat of space debris impact. These collisions occur at hypervelocity or speeds greater than 3 km/s. In order to characterize material behavior under this extreme event as well as study next-generation materials for space exploration, this paper presents a unique two-stage light-gas gun capable of replicating hypervelocity impacts. While a limited number of these types of facilities exist, they typically are extremely large and can be costly and dangerous to operate. The design presented in this paper is novel in two distinct ways. First, it does not use a form of combustion in the first stage. The projectile is accelerated from a pressure differential using air and inert gases (or purely inert gases), firing a projectile in a nominal range of 1-4 km/s. Second, the design is modular in that the first stage sits on a track sled and can be pulled back and used in itself to study lower speed impacts without any further modifications, with the first stage piston as the impactor. The modularity of the instrument allows the ability to investigate three orders of magnitude of impact velocities or between 101 and 103 m/s in a single, relatively small, cost effective instrument.

  2. Two-stage combined treatment of acid mine drainage and municipal wastewater.

    Science.gov (United States)

    Deng, Dongyang; Lin, Lian-Shin

    2013-01-01

    This study examined the feasibility of the combined treatment of field-collected acid mine drainages (AMD, pH = 4.2 ± 0.9, iron = 112 ± 118 mg/L, sulfate = 1,846 ± 594 mg/L) and municipal wastewater (MWW, avg. chemical oxygen demand (COD) = 234-333 mg/L) using a two-stage process. The process consisted of batch mixing of the two wastes to condition the mixture solutions, followed by anaerobic biological treatment. The mixings performed under a range of AMD/MWW ratios resulted in phosphate removal of 9 to ∼100%, the mixture pH of 6.2-7.9, and COD/sulfate concentration ratio of 0.05-5.4. The biological treatment consistently removed COD and sulfate by >80% from the mixture solutions for COD/sulfate ratios of 0.6-5.4. Alkalinity was produced in the biological treatment causing increased pH and further removal of metals from the solutions. Scanning electron microscopy of produced sludge with energy dispersion analysis suggested chemical precipitation and associated adsorption and co-precipitation as the mechanisms for metal removal (Fe: >99%, Al: ∼100%, Mn: 75 to ∼100%, Ca: 52-81%, Mg: 13-76%, and Na: 56-76%). The study showed promising results for the treatment method and denoted the potential of developing innovative technologies for combined management of the two wastes in mining regions.

  3. Determinan Tingkat Efisiensi Perbankan Syariah Di Indonesia: Two Stages Data Envelopment Analysis

    Directory of Open Access Journals (Sweden)

    Zulfikar Bagus Pambuko

    2016-12-01

    Full Text Available Efficiency is an important indicator to observe the banks’ ability in resisting and facing the tight rivalry at banking industry. The study aims to evaluate the efficiency and to analyze the determinants of efficiency of Islamic bank in Indonesia on 2010 – 2013 with Two-Stage Data Envelopment Analysis approach. The objects of the study are 11 Islamic banks (BUS. The first phase of testing uses the Data Envelopment Analysis (DEA method showed that the efficiency of Islamic bank is inefficient on managing the resources and small Islamic banks are more efficient than the larger. The second phase of testing uses Tobit model showed that Capital Adequacy Ratio (CAR, Return on Asset (ROA, Non Performing Financing (NPF, Financing to Deposit Ratio (FDR, and Net Interest Margin (NIM have positive significant effect on the efficiency of Islamic banks, while Good Corporate Governance (GCG has a negative significant effect. Moreover, the macroeconomic variables, such as GDP growth and inflation have no significant effect on efficiency of Islamic banks. It suggests that to realize the optimum level of Islamic banks’ efficiency is only related with bank-specific, while the volatility of macroeconomics condition contributes nothing

  4. A Two-Stage Reconstruction Processor for Human Detection in Compressive Sensing CMOS Radar.

    Science.gov (United States)

    Tsao, Kuei-Chi; Lee, Ling; Chu, Ta-Shun; Huang, Yuan-Hao

    2018-04-05

    Complementary metal-oxide-semiconductor (CMOS) radar has recently gained much research attraction because small and low-power CMOS devices are very suitable for deploying sensing nodes in a low-power wireless sensing system. This study focuses on the signal processing of a wireless CMOS impulse radar system that can detect humans and objects in the home-care internet-of-things sensing system. The challenges of low-power CMOS radar systems are the weakness of human signals and the high computational complexity of the target detection algorithm. The compressive sensing-based detection algorithm can relax the computational costs by avoiding the utilization of matched filters and reducing the analog-to-digital converter bandwidth requirement. The orthogonal matching pursuit (OMP) is one of the popular signal reconstruction algorithms for compressive sensing radar; however, the complexity is still very high because the high resolution of human respiration leads to high-dimension signal reconstruction. Thus, this paper proposes a two-stage reconstruction algorithm for compressive sensing radar. The proposed algorithm not only has lower complexity than the OMP algorithm by 75% but also achieves better positioning performance than the OMP algorithm especially in noisy environments. This study also designed and implemented the algorithm by using Vertex-7 FPGA chip (Xilinx, San Jose, CA, USA). The proposed reconstruction processor can support the 256 × 13 real-time radar image display with a throughput of 28.2 frames per second.

  5. A Two-Stage Reconstruction Processor for Human Detection in Compressive Sensing CMOS Radar

    Directory of Open Access Journals (Sweden)

    Kuei-Chi Tsao

    2018-04-01

    Full Text Available Complementary metal-oxide-semiconductor (CMOS radar has recently gained much research attraction because small and low-power CMOS devices are very suitable for deploying sensing nodes in a low-power wireless sensing system. This study focuses on the signal processing of a wireless CMOS impulse radar system that can detect humans and objects in the home-care internet-of-things sensing system. The challenges of low-power CMOS radar systems are the weakness of human signals and the high computational complexity of the target detection algorithm. The compressive sensing-based detection algorithm can relax the computational costs by avoiding the utilization of matched filters and reducing the analog-to-digital converter bandwidth requirement. The orthogonal matching pursuit (OMP is one of the popular signal reconstruction algorithms for compressive sensing radar; however, the complexity is still very high because the high resolution of human respiration leads to high-dimension signal reconstruction. Thus, this paper proposes a two-stage reconstruction algorithm for compressive sensing radar. The proposed algorithm not only has lower complexity than the OMP algorithm by 75% but also achieves better positioning performance than the OMP algorithm especially in noisy environments. This study also designed and implemented the algorithm by using Vertex-7 FPGA chip (Xilinx, San Jose, CA, USA. The proposed reconstruction processor can support the 256 × 13 real-time radar image display with a throughput of 28.2 frames per second.

  6. A two-stage stochastic rule-based model to determine pre-assembly buffer content

    Science.gov (United States)

    Gunay, Elif Elcin; Kula, Ufuk

    2018-01-01

    This study considers instant decision-making needs of the automobile manufactures for resequencing vehicles before final assembly (FA). We propose a rule-based two-stage stochastic model to determine the number of spare vehicles that should be kept in the pre-assembly buffer to restore the altered sequence due to paint defects and upstream department constraints. First stage of the model decides the spare vehicle quantities, where the second stage model recovers the scrambled sequence respect to pre-defined rules. The problem is solved by sample average approximation (SAA) algorithm. We conduct a numerical study to compare the solutions of heuristic model with optimal ones and provide following insights: (i) as the mismatch between paint entrance and scheduled sequence decreases, the rule-based heuristic model recovers the scrambled sequence as good as the optimal resequencing model, (ii) the rule-based model is more sensitive to the mismatch between the paint entrance and scheduled sequences for recovering the scrambled sequence, (iii) as the defect rate increases, the difference in recovery effectiveness between rule-based heuristic and optimal solutions increases, (iv) as buffer capacity increases, the recovery effectiveness of the optimization model outperforms heuristic model, (v) as expected the rule-based model holds more inventory than the optimization model.

  7. Montessori Preschool Elevates and Equalizes Child Outcomes: A Longitudinal Study.

    Science.gov (United States)

    Lillard, Angeline S; Heise, Megan J; Richey, Eve M; Tong, Xin; Hart, Alyssa; Bray, Paige M

    2017-01-01

    Quality preschool programs that develop the whole child through age-appropriate socioemotional and cognitive skill-building hold promise for significantly improving child outcomes. However, preschool programs tend to either be teacher-led and didactic, or else to lack academic content. One preschool model that involves both child-directed, freely chosen activity and academic content is Montessori. Here we report a longitudinal study that took advantage of randomized lottery-based admission to two public Montessori magnet schools in a high-poverty American city. The final sample included 141 children, 70 in Montessori and 71 in other schools, most of whom were tested 4 times over 3 years, from the first semester to the end of preschool (ages 3-6), on a variety of cognitive and socio-emotional measures. Montessori preschool elevated children's outcomes in several ways. Although not different at the first test point, over time the Montessori children fared better on measures of academic achievement, social understanding, and mastery orientation, and they also reported relatively more liking of scholastic tasks. They also scored higher on executive function when they were 4. In addition to elevating overall performance on these measures, Montessori preschool also equalized outcomes among subgroups that typically have unequal outcomes. First, the difference in academic achievement between lower income Montessori and higher income conventionally schooled children was smaller at each time point, and was not (statistically speaking) significantly different at the end of the study. Second, defying the typical finding that executive function predicts academic achievement, in Montessori classrooms children with lower executive function scored as well on academic achievement as those with higher executive function. This suggests that Montessori preschool has potential to elevate and equalize important outcomes, and a larger study of public Montessori preschools is warranted.

  8. Montessori Preschool Elevates and Equalizes Child Outcomes: A Longitudinal Study

    Directory of Open Access Journals (Sweden)

    Angeline S. Lillard

    2017-10-01

    Full Text Available Quality preschool programs that develop the whole child through age-appropriate socioemotional and cognitive skill-building hold promise for significantly improving child outcomes. However, preschool programs tend to either be teacher-led and didactic, or else to lack academic content. One preschool model that involves both child-directed, freely chosen activity and academic content is Montessori. Here we report a longitudinal study that took advantage of randomized lottery-based admission to two public Montessori magnet schools in a high-poverty American city. The final sample included 141 children, 70 in Montessori and 71 in other schools, most of whom were tested 4 times over 3 years, from the first semester to the end of preschool (ages 3–6, on a variety of cognitive and socio-emotional measures. Montessori preschool elevated children’s outcomes in several ways. Although not different at the first test point, over time the Montessori children fared better on measures of academic achievement, social understanding, and mastery orientation, and they also reported relatively more liking of scholastic tasks. They also scored higher on executive function when they were 4. In addition to elevating overall performance on these measures, Montessori preschool also equalized outcomes among subgroups that typically have unequal outcomes. First, the difference in academic achievement between lower income Montessori and higher income conventionally schooled children was smaller at each time point, and was not (statistically speaking significantly different at the end of the study. Second, defying the typical finding that executive function predicts academic achievement, in Montessori classrooms children with lower executive function scored as well on academic achievement as those with higher executive function. This suggests that Montessori preschool has potential to elevate and equalize important outcomes, and a larger study of public Montessori

  9. Changes in taste preference after colorectal surgery: A longitudinal study.

    Science.gov (United States)

    Welchman, Sophie; Hiotis, Perryhan; Pengelly, Steven; Hughes, Georgina; Halford, Jason; Christiansen, Paul; Lewis, Stephen

    2015-10-01

    Nutrition is a key component of surgical enhanced recovery programmes. However, alterations in food preferences are often reported as reasons for patients not eating in the early postoperative period. We hypothesised that taste preferences are altered in the early postoperative period and this dysgeusia affects patients' food choices during this critical time. This is a longitudinal study looking at taste preferences of patients recovering from surgery. Patients undergoing colonic resections were recruited. Using visual analogue scales participants completed a questionnaire, taste tests and preference scoring of food images for the 6 groups of taste (bitter, salty, savoury, sour, spicy and sweet) preoperatively and on postoperative days 1-3. Patients were also offered snacks postoperatively, which represented foods from the six groups and consumption was measured. Differences from baseline were assessed using the Friedman's and Wilcoxon tests. 31 patients were studied. In the immediate postoperative period participants reported deterioration in their sense of taste (p ≤ 0.001), increased nausea (p palatability for salty taste increased (p = 0.001) following surgery. The highest rated images were for savoury food with only the ratings for salty food increasing after surgery (p foods in the postoperative period. Bitter, sour and spicy foods were the least frequently consumed. This is the first study to investigate postsurgical patients' food preferences. A consistent change in all the individual tastes with the exception of salty in the postoperative period was observed. The most desirable tastes were for savoury and sweet, reflecting patients' preoperative preferences. An improved understanding of taste may improve the resumption of eating after colonic surgery. Copyright © 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  10. Ten-Year Retrospective Longitudinal-Study of Student Perspectives on Value of REU

    Science.gov (United States)

    Slater, T. F.; Slater, S. J.

    2013-12-01

    For more than two decades, federal agencies have been enthusiastically supporting summer research experiences for undergraduates. These REU programs are tacitly intended to increase retention and provide "an important educational experience" for undergraduates, particularly women, minorities and underrepresented groups. Numerous authors (viz., Laursen, Lopatto, Dolan, among many others) have enthusiastically described positive impacts of summer REU programs from exit interview data. These results include enhanced persistence to pursue STEM careers and confirmed desire to attend graduate school in the field targeted by a particular REU. Perhaps surprisingly, negative student experiences are rarely described in the scholarly literature, but do appear in more informal publications (viz., Gueterma, 2007). One wonders how REU alumni, looking back over their entire collective portfolio of experiences, now perceive the educational value of their REU experience relative to their other educational experiences. To obtain a backwards-looking, reflective description from REU alumni on the value of their REU experiences, we conducted a 10-year, two-stage study was designed to explore the ways in which the REU acted as an educational experience for 51 women from a single geoscience sub-discipline. The first phase was an ex post facto longitudinal analysis of data, including multiple interviews with each participant during their REU, annual open-ended alumni surveys, faculty interviews, and extensive field notes, over a 10-year period. This analysis informed the second phase, a clinical interview. Over 10 hours of interviews with 8 participants were conducted and analyzed. These 8 participants were selected to represent a variety of career stages, and for their potential to reflect on a wide variety of educational experiences. Results from the interviews, done many years after their REU experience, indicate that the interviewees' REU did not provide a substantive educational

  11. Longitudinal variability of time-location/activity patterns of population at different ages: a longitudinal study in California

    Directory of Open Access Journals (Sweden)

    Cassady Diana L

    2011-09-01

    Full Text Available Abstract Background Longitudinal time-activity data are important for exposure modeling, since the extent to which short-term time-activity data represent long-term activity patterns is not well understood. This study was designed to evaluate longitudinal variations in human time-activity patterns. Method We report on 24-hour recall diaries and questionnaires collected via the internet from 151 parents of young children (mostly under age 55, and from 55 older adults of ages 55 and older, for both a weekday and a weekend day every three months over an 18-month period. Parents also provided data for their children. The self-administrated diary and questionnaire distinguished ~30 frequently visited microenvironments and ~20 activities which we selected to represent opportunities for exposure to toxic environmental compounds. Due to the non-normal distribution of time-location/activity data, we employed generalized linear mixed-distribution mixed-effect models to examine intra- and inter-individual variations. Here we describe variation in the likelihood of and time spent engaging in an activity or being in a microenvironment by age group, day-type (weekday/weekend, season (warm/cool, sex, employment status, and over the follow-up period. Results As expected, day-type and season influence time spent in many location and activity categories. Longitudinal changes were also observed, e.g., young children slept less with increasing follow-up, transit time increased, and time spent on working and shopping decreased during the study, possibly related to human physiological changes with age and changes in macro-economic factors such as gas prices and the economic recession. Conclusions This study provides valuable new information about time-activity assessed longitudinally in three major age groups and greatly expands our knowledge about intra- and inter-individual variations in time-location/activity patterns. Longitudinal variations beyond weekly and

  12. Two-Stage Robust Security-Constrained Unit Commitment with Optimizable Interval of Uncertain Wind Power Output

    Directory of Open Access Journals (Sweden)

    Dayan Sun

    2017-01-01

    Full Text Available Because wind power spillage is barely considered, the existing robust unit commitment cannot accurately analyze the impacts of wind power accommodation on on/off schedules and spinning reserve requirements of conventional generators and cannot consider the network security limits. In this regard, a novel double-level robust security-constrained unit commitment formulation with optimizable interval of uncertain wind power output is firstly proposed in this paper to obtain allowable interval solutions for wind power generation and provide the optimal schedules for conventional generators to cope with the uncertainty in wind power generation. The proposed double-level model is difficult to be solved because of the invalid dual transform in solution process caused by the coupling relation between the discrete and continuous variables. Therefore, a two-stage iterative solution method based on Benders Decomposition is also presented. The proposed double-level model is transformed into a single-level and two-stage robust interval unit commitment model by eliminating the coupling relation, and then this two-stage model can be solved by Benders Decomposition iteratively. Simulation studies on a modified IEEE 26-generator reliability test system connected to a wind farm are conducted to verify the effectiveness and advantages of the proposed model and solution method.

  13. The dynamics of patients' life quality indices under the conditions of two-stage knee joint replacement

    Directory of Open Access Journals (Sweden)

    Shpinyak S.P.

    2017-09-01

    Full Text Available  The aim: to analyze the changes in the life quality indices of the patients with deep periprosthetic joint infection of the knee under the two-stage surgical treatment. Material and Methods. 57 patients who underwent two-stage revision-ary treatment in Research Institute of Traumatology, Orthopedics and Neurosurgery were interviewed with life quality questionnaire Short Form Medical Outcomes Study (SF 36 v.1. Interview results were compared with standardized population indices of SF-36 scales for males and females. Results. In all groups regardless of sex there was a general tendency for an increase in physical and psychological health component up to mean population values after the first stage of surgery and further growth after the second stage. Rehabilitation potential of psychomotor health was higher in women than in men. The ability to handle stress was lower in direct ratio with the patients' age. Conclusion. Two-stage reendoprosthetic treatment with articulating antimicrobial spacer implantation having high grade of fixation is an effective treatment method for deep periprosthetic infection which increases physical health and improves social functioning of patients.

  14. Two-stage pervaporation process for effective in situ removal acetone-butanol-ethanol from fermentation broth.

    Science.gov (United States)

    Cai, Di; Hu, Song; Miao, Qi; Chen, Changjing; Chen, Huidong; Zhang, Changwei; Li, Ping; Qin, Peiyong; Tan, Tianwei

    2017-01-01

    Two-stage pervaporation for ABE recovery from fermentation broth was studied to reduce the energy cost. The permeate after the first stage in situ pervaporation system was further used as the feedstock in the second stage of pervaporation unit using the same PDMS/PVDF membrane. A total 782.5g/L of ABE (304.56g/L of acetone, 451.98g/L of butanol and 25.97g/L of ethanol) was achieved in the second stage permeate, while the overall acetone, butanol and ethanol separation factors were: 70.7-89.73, 70.48-84.74 and 9.05-13.58, respectively. Furthermore, the theoretical evaporation energy requirement for ABE separation in the consolidate fermentation, which containing two-stage pervaporation and the following distillation process, was estimated less than ∼13.2MJ/kg-butanol. The required evaporation energy was only 36.7% of the energy content of butanol. The novel two-stage pervaporation process was effective in increasing ABE production and reducing energy consumption of the solvents separation system. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Design and construction of the X-2 two-stage free piston driven expansion tube

    Science.gov (United States)

    Doolan, Con

    1995-01-01

    This report outlines the design and construction of the X-2 two-stage free piston driven expansion tube. The project has completed its construction phase and the facility has been installed in the new impulsive research laboratory where commissioning is about to take place. The X-2 uses a unique, two-stage driver design which allows a more compact and lower overall cost free piston compressor. The new facility has been constructed in order to examine the performance envelope of the two-stage driver and how well it couple to sub-orbital and super-orbital expansion tubes. Data obtained from these experiments will be used for the design of a much larger facility, X-3, utilizing the same free piston driver concept.

  16. Orthodontic treatment stability predictors: A retrospective longitudinal study.

    Science.gov (United States)

    de Bernabé, Paloma González-Gil; Montiel-Company, José María; Paredes-Gallardo, Vanessa; Gandía-Franco, Jose Luis; Bellot-Arcís, Carlos

    2017-03-01

    To examine medium- to long-term orthodontic treatment stability and its possible association with certain variables. In a retrospective longitudinal study of 70 postretention patients, the Peer Assessment Rating (PAR) index was measured at the start (T1) and end (T2) of treatment and between 4 and 10 years afterwards (T3). The stability was considered absolute when the T2 and T3 values were identical and relative when the difference was within the ±5 range. Among the 70 patients, 65.8% were female and 34.2% were male. Their mean age was 14.5 years. The mean treatment length was 2.4 years. The mean retention phase was 3.3 years. The mean pre- and posttreatment PAR scores were 29.8 (T1) and 6.3 (T2). The mean T1-T2 difference was 23.6. The mean T2-T3 difference was -0.39. Within the study, 7.1% presented absolute stability and 68.6% presented relative stability. Lower anterior segment alignment and overbite were the most unstable occlusal features and tended to worsen. Fixed retainer (odds ratio [OR] 0.31; 95% confidence interval [CI] 0.10-0.98) as a protective factor and years without retention (OR 1.32; 95% CI 1.03-1.68) as a risk factor are predictor variables of instability in the case of lower anterior segment alignment. The PAR value at the end of treatment (OR 1.29; 95% CI 1.08-1.54) and extractions (OR 4.76; 95% CI 1.05-21.6) before treatment are predictors for midline instability.

  17. Comparing Longitudinal Profile Patterns of Mathematics and Reading in Early Child Longitudinal Study, Kindergarten: The Profile Analysis via Multidimensional Scaling (PAMS) Approach

    Science.gov (United States)

    Kim, Se-Kang

    2010-01-01

    The aim of the study is to compare longitudinal patterns from Mathematics and Reading data from the direct child assessment of Early Child Longitudinal Study, Kindergarten (ECLS-K, US Department of Education, National Center for Education Statistics 2006), utilizing Profile Analysis via Multidimensional Scaling (PAMS). PAMS has been used initially…

  18. Normal Theory Two-Stage ML Estimator When Data Are Missing at the Item Level.

    Science.gov (United States)

    Savalei, Victoria; Rhemtulla, Mijke

    2017-08-01

    In many modeling contexts, the variables in the model are linear composites of the raw items measured for each participant; for instance, regression and path analysis models rely on scale scores, and structural equation models often use parcels as indicators of latent constructs. Currently, no analytic estimation method exists to appropriately handle missing data at the item level. Item-level multiple imputation (MI), however, can handle such missing data straightforwardly. In this article, we develop an analytic approach for dealing with item-level missing data-that is, one that obtains a unique set of parameter estimates directly from the incomplete data set and does not require imputations. The proposed approach is a variant of the two-stage maximum likelihood (TSML) methodology, and it is the analytic equivalent of item-level MI. We compare the new TSML approach to three existing alternatives for handling item-level missing data: scale-level full information maximum likelihood, available-case maximum likelihood, and item-level MI. We find that the TSML approach is the best analytic approach, and its performance is similar to item-level MI. We recommend its implementation in popular software and its further study.

  19. A two-stage bioprocess for hydrogen and methane production from rice straw bioethanol residues.

    Science.gov (United States)

    Cheng, Hai-Hsuan; Whang, Liang-Ming; Wu, Chao-Wei; Chung, Man-Chien

    2012-06-01

    This study evaluates a two-stage bioprocess for recovering hydrogen and methane while treating organic residues of fermentative bioethanol from rice straw. The obtained results indicate that controlling a proper volumetric loading rate, substrate-to-biomass ratio, or F/M ratio is important to maximizing biohydrogen production from rice straw bioethanol residues. Clostridium tyrobutyricum, the identified major hydrogen-producing bacteria enriched in the hydrogen bioreactor, is likely utilizing lactate and acetate for biohydrogen production. The occurrence of acetogenesis during biohydrogen fermentation may reduce the B/A ratio and lead to a lower hydrogen production. Organic residues remained in the effluent of hydrogen bioreactor can be effectively converted to methane with a rate of 2.8 mmol CH(4)/gVSS/h at VLR of 4.6 kg COD/m(3)/d. Finally, approximately 75% of COD in rice straw bioethanol residues can be removed and among that 1.3% and 66.1% of COD can be recovered in the forms of hydrogen and methane, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Antioxidant activity and total phenolic content of Moringa oleifera leaves in two stages of maturity.

    Science.gov (United States)

    Sreelatha, S; Padma, P R

    2009-12-01

    Antioxidants play an important role in inhibiting and scavenging free radicals, thus providing protection to human against infections and degenerative diseases. Current research is now directed towards natural antioxidants originated from plants due to safe therapeutics. Moringa oleifera is used in Indian traditional medicine for a wide range of various ailments. To understand the mechanism of pharmacological actions, antioxidant properties of the Moringa oleifera leaf extracts were tested in two stages of maturity using standard in vitro models. The successive aqueous extract of Moringa oleifera exhibited strong scavenging effect on 2, 2-diphenyl-2-picryl hydrazyl (DPPH) free radical, superoxide, nitric oxide radical and inhibition of lipid per oxidation. The free radical scavenging effect of Moringa oleifera leaf extract was comparable with that of the reference antioxidants. The data obtained in the present study suggests that the extracts of Moringa oleifera both mature and tender leaves have potent antioxidant activity against free radicals, prevent oxidative damage to major biomolecules and afford significant protection against oxidative damage.

  1. Two-stage light-gas magnetoplasma accelerator for hypervelocity impact simulation

    International Nuclear Information System (INIS)

    Khramtsov, P P; Vasetskij, V A; Makhnach, A I; Grishenko, V M; Chernik, M Yu; Shikh, I A; Doroshko, M V

    2016-01-01

    The development of macroparticles acceleration methods for high-speed impact simulation in a laboratory is an actual problem due to increasing of space flights duration and necessity of providing adequate spacecraft protection against micrometeoroid and space debris impacts. This paper presents results of experimental study of a two-stage light- gas magnetoplasma launcher for acceleration of a macroparticle, in which a coaxial plasma accelerator creates a shock wave in a high-pressure channel filled with light gas. Graphite and steel spheres with diameter of 2.5-4 mm were used as a projectile and were accelerated to the speed of 0.8-4.8 km/s. A launching of particle occurred in vacuum. For projectile velocity control the speed measuring method was developed. The error of this metod does not exceed 5%. The process of projectile flight from the barrel and the process of a particle collision with a target were registered by use of high-speed camera. The results of projectile collision with elements of meteoroid shielding are presented. In order to increase the projectile velocity, the high-pressure channel should be filled with hydrogen. However, we used helium in our experiments for safety reasons. Therefore, we can expect that the range of mass and velocity of the accelerated particles can be extended by use of hydrogen as an accelerating gas. (paper)

  2. Two-stage light-gas magnetoplasma accelerator for hypervelocity impact simulation

    Science.gov (United States)

    Khramtsov, P. P.; Vasetskij, V. A.; Makhnach, A. I.; Grishenko, V. M.; Chernik, M. Yu; Shikh, I. A.; Doroshko, M. V.

    2016-11-01

    The development of macroparticles acceleration methods for high-speed impact simulation in a laboratory is an actual problem due to increasing of space flights duration and necessity of providing adequate spacecraft protection against micrometeoroid and space debris impacts. This paper presents results of experimental study of a two-stage light- gas magnetoplasma launcher for acceleration of a macroparticle, in which a coaxial plasma accelerator creates a shock wave in a high-pressure channel filled with light gas. Graphite and steel spheres with diameter of 2.5-4 mm were used as a projectile and were accelerated to the speed of 0.8-4.8 km/s. A launching of particle occurred in vacuum. For projectile velocity control the speed measuring method was developed. The error of this metod does not exceed 5%. The process of projectile flight from the barrel and the process of a particle collision with a target were registered by use of high-speed camera. The results of projectile collision with elements of meteoroid shielding are presented. In order to increase the projectile velocity, the high-pressure channel should be filled with hydrogen. However, we used helium in our experiments for safety reasons. Therefore, we can expect that the range of mass and velocity of the accelerated particles can be extended by use of hydrogen as an accelerating gas.

  3. Evaluation of carcinogenic potential of diuron in a rat mammary two-stage carcinogenesis model.

    Science.gov (United States)

    Grassi, Tony Fernando; Rodrigues, Maria Aparecida Marchesan; de Camargo, João Lauro Viana; Barbisan, Luís Fernando

    2011-04-01

    This study aimed to evaluate the carcinogenic potential of the herbicide Diuron in a two-stage rat medium-term mammary carcinogenesis model initiated by 7,12-dimethylbenz(a)anthracene (DMBA). Female seven-week-old Sprague-Dawley (SD) rats were allocated to six groups: groups G1 to G4 received intragastrically (i.g.) a single 50 mg/kg dose of DMBA; groups G5 and G6 received single administration of canola oil (vehicle of DMBA). Groups G1 and G5 received a basal diet, and groups G2, G3, G4, and G6 were fed the basal diet with the addition of Diuron at 250, 1250, 2500, and 2500 ppm, respectively. After twenty-five weeks, the animals were euthanized and mammary tumors were histologically confirmed and quantified. Tumor samples were also processed for immunohistochemical evaluation of the expressions of proliferating cell nuclear antigen (PCNA), cleaved caspase-3, estrogen receptor-α (ER-α), p63, bcl-2, and bak. Diuron treatment did not increase the incidence or multiplicity of mammary tumors (groups G2 to G4 versus Group G1). Also, exposure to Diuron did not alter tumor growth (cell proliferation and apoptosis indexes) or immunoreactivity to ER-α, p63 (myoephitelial marker), or bcl-2 and bak (apoptosis regulatory proteins). These findings indicate that Diuron does not have a promoting potential on mammary carcinogenesis in female SD rats initiated with DMBA.

  4. Stepwise encapsulation and controlled two-stage release system for cis-Diamminediiodoplatinum

    Directory of Open Access Journals (Sweden)

    Chen Y

    2014-06-01

    Full Text Available Yun Chen,1,* Qian Li,1,2,* Qingsheng Wu1 1Department of Chemistry, Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shanghai; 2Shanghai Institute of Quality Inspection and Technical Research, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: cis-Diamminediiodoplatinum (cis-DIDP is a cisplatin-like anticancer drug with higher anticancer activity, but lower stability and price than cisplatin. In this study, a cis-DIDP carrier system based on micro-sized stearic acid was prepared by an emulsion solvent evaporation method. The maximum drug loading capacity of cis-DIDP-loaded solid lipid nanoparticles was 22.03%, and their encapsulation efficiency was 97.24%. In vitro drug release in phosphate-buffered saline (pH =7.4 at 37.5°C exhibited a unique two-stage process, which could prove beneficial for patients with tumors and malignancies. MTT (3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide assay results showed that cis-DIDP released from cis-DIDP-loaded solid lipid nanoparticles had better inhibition activity than cis-DIDP that had not been loaded. Keywords: stearic acid, emulsion solvent evaporation method, drug delivery, cis-DIDP, in vitro

  5. Two-Stage Dynamic Pricing and Advertising Strategies for Online Video Services

    Directory of Open Access Journals (Sweden)

    Zhi Li

    2017-01-01

    Full Text Available As the demands for online video services increase intensively, the selection of business models has drawn the great attention of online providers. Among them, pay-per-view mode and advertising mode are two important resource modes, where the reasonable fee charge and suitable volume of ads need to be determined. This paper establishes an analytical framework studying the optimal dynamic pricing and advertising strategies for online providers; it shows how the strategies are influenced by the videos available time and the viewers’ emotional factor. We create the two-stage strategy of revenue models involving a single fee mode and a mixed fee-free mode and find out the optimal fee charge and advertising level of online video services. According to the results, the optimal video price and ads volume dynamically vary over time. The viewer’s aversion level to advertising has direct effects on both the volume of ads and the number of viewers who have selected low-quality content. The optimal volume of ads decreases with the increase of ads-aversion coefficient, while increasing as the quality of videos increases. The results also indicate that, in the long run, a pure fee mode or free mode is the optimal strategy for online providers.

  6. Armature formation in a railgun using a two-stage light-gas gun injector

    International Nuclear Information System (INIS)

    Hawke, R.S.; Susoeff, A.R.; Asay, J.R.; Hall, C.A.; Konrad, C.H.; Hickman, R.J.; Sauve, J.L.

    1989-01-01

    During the past decade several research groups have tried to achieve reliable acceleration of projectiles to velocities in excess of 8 km/s by using a railgun. All attempts have met with difficulties. However, in the past four years the researchers have come to agree on the nature and causes of the difficulties. The consensus is that the hot plasma armature - used to commutate across the rails and to accelerate the projectile - causes ablation of the barrel wall; this ablation ultimately results in parasitic secondary arc formation through armature separation and/or restrike. The subsequence deprivation of current to the propulsion armature results in a limit to the achievable projectile velocity. Methods of mitigating the process are under study. One method uses a two-stage light-gas gun as a preaccelerator/injector to the railgun. The gas gun serves a double purpose: It quickly accelerates the projectile to a high velocity, and it fills the barrel behind the propulsive armature with insulating gas. While this approach is expected to improve railgun performance, it also requires development of techniques to form the propulsive armature behind the projectile in the high-velocity, high-pressure gas stream. This paper briefly summarizes the problems encountered in attempts to achieve hypervelocities with a railgun. Included is a description of the phenomenology and details of joint Sandia National Laboratories, Albuquerque/Lawrence Livermore National Laboratory (SNLA/LNLL) work at SNLA on a method for forming the needed plasma armature

  7. Two stages of directed forgetting: Electrophysiological evidence from a short-term memory task.

    Science.gov (United States)

    Gao, Heming; Cao, Bihua; Qi, Mingming; Wang, Jing; Zhang, Qi; Li, Fuhong

    2016-06-01

    In this study, a short-term memory test was used to investigate the temporal course and neural mechanism of directed forgetting under different memory loads. Within each trial, two memory items with high or low load were presented sequentially, followed by a cue indicating whether the presented items should be remembered. After an interval, subjects were asked to respond to the probe stimuli. The ERPs locked to the cues showed that (a) the effect of cue type was initially observed during the P2 (160-240 ms) time window, with more positive ERPs for remembering relative to forgetting cues; (b) load effects were observed during the N2-P3 (250-500 ms) time window, with more positive ERPs for the high-load than low-load condition; (c) the cue effect was also observed during the N2-P3 time window, with more negative ERPs for forgetting versus remembering cues. These results demonstrated that directed forgetting involves two stages: task-relevance identification and information discarding. The cue effects during the N2 epoch supported the view that directed forgetting is an active process. © 2016 Society for Psychophysiological Research.

  8. Computational Modelling of Large Scale Phage Production Using a Two-Stage Batch Process

    Directory of Open Access Journals (Sweden)

    Konrad Krysiak-Baltyn

    2018-04-01

    Full Text Available Cost effective and scalable methods for phage production are required to meet an increasing demand for phage, as an alternative to antibiotics. Computational models can assist the optimization of such production processes. A model is developed here that can simulate the dynamics of phage population growth and production in a two-stage, self-cycling process. The model incorporates variable infection parameters as a function of bacterial growth rate and employs ordinary differential equations, allowing application to a setup with multiple reactors. The model provides simple cost estimates as a function of key operational parameters including substrate concentration, feed volume and cycling times. For the phage and bacteria pairing examined, costs and productivity varied by three orders of magnitude, with the lowest cost found to be most sensitive to the influent substrate concentration and low level setting in the first vessel. An example case study of phage production is also presented, showing how parameter values affect the production costs and estimating production times. The approach presented is flexible and can be used to optimize phage production at laboratory or factory scale by minimizing costs or maximizing productivity.

  9. Performance analysis of a potassium-steam two stage vapour cycle

    International Nuclear Information System (INIS)

    Mitachi, Kohshi; Saito, Takeshi

    1983-01-01

    It is an important subject to raise the thermal efficiency in thermal power plants. In present thermal power plants which use steam cycle, the plant thermal efficiency has already reached 41 to 42 %, steam temperature being 839 K, and steam pressure being 24.2 MPa. That is, the thermal efficiency in a steam cycle is facing a limit. In this study, analysis was made on the performance of metal vapour/steam two-stage Rankine cycle obtained by combining a metal vapour cycle with a present steam cycle. Three different combinations using high temperature potassium regenerative cycle and low temperature steam regenerative cycle, potassium regenerative cycle and steam reheat and regenerative cycle, and potassium bleed cycle and steam reheat and regenerative cycle were systematically analyzed for the overall thermal efficiency, the output ratio and the flow rate ratio, when the inlet temperature of a potassium turbine, the temperature of a potassium condenser, and others were varied. Though the overall thermal efficiency was improved by lowering the condensing temperature of potassium vapour, it is limited by the construction because the specific volume of potassium in low pressure section increases greatly. In the combinatipn of potassium vapour regenerative cycle with steam regenerative cycle, the overall thermal efficiency can be 58.5 %, and also 60.2 % if steam reheat and regenerative cycle is employed. If a cycle to heat steam with the bled vapor out of a potassium vapour cycle is adopted, the overall thermal efficiency of 63.3 % is expected. (Wakatsuki, Y.)

  10. Non-ideal magnetohydrodynamic simulations of the two-stage fragmentation model for cluster formation

    International Nuclear Information System (INIS)

    Bailey, Nicole D.; Basu, Shantanu

    2014-01-01

    We model molecular cloud fragmentation with thin-disk, non-ideal magnetohydrodynamic simulations that include ambipolar diffusion and partial ionization that transitions from primarily ultraviolet-dominated to cosmic-ray-dominated regimes. These simulations are used to determine the conditions required for star clusters to form through a two-stage fragmentation scenario. Recent linear analyses have shown that the fragmentation length scales and timescales can undergo a dramatic drop across the column density boundary that separates the ultraviolet- and cosmic-ray-dominated ionization regimes. As found in earlier studies, the absence of an ionization drop and regular perturbations leads to a single-stage fragmentation on pc scales in transcritical clouds, so that the nonlinear evolution yields the same fragment sizes as predicted by linear theory. However, we find that a combination of initial transcritical mass-to-flux ratio, evolution through a column density regime in which the ionization drop takes place, and regular small perturbations to the mass-to-flux ratio is sufficient to cause a second stage of fragmentation during the nonlinear evolution. Cores of size ∼0.1 pc are formed within an initial fragment of ∼pc size. Regular perturbations to the mass-to-flux ratio also accelerate the onset of runaway collapse.

  11. Addition of seaweed and bentonite accelerates the two-stage composting of green waste.

    Science.gov (United States)

    Zhang, Lu; Sun, Xiangyang

    2017-11-01

    Green waste (GW) is an important recyclable resource, and composting is an effective technology for the recycling of organic solid waste, including GW. This study investigated the changes in physical and chemical characteristics during the two-stage composting of GW with or without addition of seaweed (SW, Ulva ohnoi) (at 0, 35, and 55%) and bentonite (BT) (at 0.0, 2.5%, and 4.5%). During the bio-oxidative phase, the combined addition of SW and BT improved the physicochemical conditions, increased the respiration rate and enzyme activities, and decreased ammonia and nitrous oxide emissions. The combination of SW and BT also enhanced the quality of the final compost in terms of water-holding capacity, porosity, particle-size distribution, water soluble organic carbon/organic nitrogen ratio, humification, nutrient content, and phytotoxicity. The best quality compost, which matured in only 21days, was obtained with 35% SW and 4.5% BT. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Design and Analysis of a Split Deswirl Vane in a Two-Stage Refrigeration Centrifugal Compressor

    Directory of Open Access Journals (Sweden)

    Jeng-Min Huang

    2014-09-01

    Full Text Available This study numerically investigated the influence of using the second row of a double-row deswirl vane as the inlet guide vane of the second stage on the performance of the first stage in a two-stage refrigeration centrifugal compressor. The working fluid was R134a, and the turbulence model was the Spalart-Allmaras model. The parameters discussed included the cutting position of the deswirl vane, the staggered angle of two rows of vane, and the rotation angle of the second row. The results showed that the performance of staggered angle 7.5° was better than that of 15° or 22.5°. When the staggered angle was 7.5°, the performance of cutting at 1/3 and 1/2 of the original deswirl vane length was slightly different from that of the original vane but obviously better than that of cutting at 2/3. When the staggered angle was 15°, the cutting position influenced the performance slightly. At a low flow rate prone to surge, when the second row at a staggered angle 7.5° cutting at the half of vane rotated 10°, the efficiency was reduced by only about 0.6%, and 10% of the swirl remained as the preswirl of the second stage, which is generally better than other designs.

  13. Changes in HRM in Europe: A Longitudinal Comparative Study among 18 European Countries

    Science.gov (United States)

    Nikandrou, Irene; Apospori, Eleni; Papalexandris, Nancy

    2005-01-01

    Purpose: To examine HRM strategies and practices and HRM position within organizations in various cultural, economic and sociopolitical contexts from a longitudinal perspective. Design/methodology/approach: The study uses the 1995 and 1999 Cranet data in a longitudinal methodological framework to explore the changes and trends in 18 European…

  14. A Longitudinal Study of Children's Social Behaviors and Their Causal Relationship to Reading Growth

    Science.gov (United States)

    Lim, Hyo Jin; Kim, Junyeop

    2011-01-01

    This paper aims at investigating the causal effects of social behaviors on subsequent reading growth in elementary school, using the "Early Childhood Longitudinal Study-Kindergarten" ("ECLS-K") data. The sample was 8,869 subjects who provided longitudinal measures of reading IRT scores from kindergarten (1998-1999) to fifth…

  15. Ultrafast X-ray absorption study of longitudinal-transverse phonon coupling in electrolyte aqueous solution

    DEFF Research Database (Denmark)

    Jiao, Yishuo; Adams, Bernhard W.; Dohn, Asmus Ougaard

    2017-01-01

    Ultrafast X-ray absorption spectroscopy is applied to study the conversion of longitudinal to transverse phonons in aqueous solution. Permanganate solutes serve as X-ray probe molecules that permit the measurement of the conversion of 13.5 GHz, longitudinal phonons to 27 GHz, transverse phonons...

  16. Kinetics analysis of two-stage austenitization in supermartensitic stainless steel

    DEFF Research Database (Denmark)

    Nießen, Frank; Villa, Matteo; Hald, John

    2017-01-01

    The martensite-to-austenite transformation in X4CrNiMo16-5-1 supermartensitic stainless steel was followed in-situ during isochronal heating at 2, 6 and 18 K min−1 applying energy-dispersive synchrotron X-ray diffraction at the BESSY II facility. Austenitization occurred in two stages, separated...... that the austenitization kinetics is governed by Ni-diffusion and that slow transformation kinetics separating the two stages is caused by soft impingement in the martensite phase. Increasing the lath width in the kinetics model had a similar effect on the austenitization kinetics as increasing the heating-rate....

  17. One-stage and two-stage penile buccal mucosa urethroplasty

    Directory of Open Access Journals (Sweden)

    G. Barbagli

    2016-03-01

    Full Text Available The paper provides the reader with the detailed description of current techniques of one-stage and two-stage penile buccal mucosa urethroplasty. The paper provides the reader with the preoperative patient evaluation paying attention to the use of diagnostic tools. The one-stage penile urethroplasty using buccal mucosa graft with the application of glue is preliminary showed and discussed. Two-stage penile urethroplasty is then reported. A detailed description of first-stage urethroplasty according Johanson technique is reported. A second-stage urethroplasty using buccal mucosa graft and glue is presented. Finally postoperative course and follow-up are addressed.

  18. Longitudinal study of computerized cardiotocography in early fetal growth restriction

    NARCIS (Netherlands)

    Wolf, H.; Arabin, B.; Lees, Christoph C.; Oepkes, D.; Prefumo, Federico; Thilaganathan, B.; Todros, T.; Visser, G.H.A.; Bilardo, Caterina M.; Derks, J. B.; Diemert, A.; Duvekot, Johannes J.; Ferrazzi, E.; Frusca, T.; Hecher, K.; Marlow, N.; Martinelli, P.; Ostermayer, E.; Papageorghiou, Aris T.; Scheepers, Hubertina C. J.; Schlembach, D.; Schneider, K. T M; Valcamonico, A.; van Wassenaer-Leemhuis, A.; Ganzevoort, W.; Aktas, Ayse; Borgione, Silvia; Brezinka, Christoph; Calvert, Sandra; Chaoui, Rabih; Cornette, Jerome M J; Diehl, Thilo; van Eyck, Jim; Fratelli, Nicola; van Haastert, Inge Lot; Johnson, Samantha; Lobmaier, Silvia; Lopriore, Enrico; Mansi, Giuseppina; Missfelder-Lobos, Hannah; Martelli, Paola; Maso, Gianpaolo; Maurer-Fellbaum, Ute; Van Charante, Nico Mensing; De Tollenaer, Susanne Mulder; Moore, Tamanna; Napolitano, Raffaele; Oberto, Manuela; Ogge, Giovanna; van der Post, Joris Am; Preston, Lucy; Raimondi, Francesco; Reiss, Irwin K M; Rigano, Serena; Schuit, Ewoud; Skabar, Aldo; Spaanderman, Marc E.; Weisglas-Kuperus, Nynke; Zimmermann, Andrea

    2017-01-01

    Objectives: To explore whether, in early fetal growth restriction (FGR), the longitudinal pattern of fetal heart rate (FHR) short-term variation (STV) can be used to identify imminent fetal distress and whether abnormalities of FHR recordings are associated with 2-year infant outcome. Methods: The

  19. A Chinese Longitudinal Study on Work/Family Enrichment

    Science.gov (United States)

    Lu, Luo

    2011-01-01

    Purpose: The purpose of this paper is to explore reciprocal relationships between work/family resources, work/family enrichment (WFE), and work/family satisfaction in a Chinese society. Design/methodology/approach: A longitudinal design was adopted using a three-wave panel sample. Data were obtained from 310 Taiwanese employees on three occasions,…

  20. A Longitudinal Study of Accounting Students' Ethical Judgement Making Ability

    Science.gov (United States)

    Mohamed Saat, Maisarah; Porter, Stacey; Woodbine, Gordon

    2012-01-01

    This paper reports the effect of a moral education programme on the ethical judgement making ability of university students. The programme comprises two forms of intervention: a dedicated ethics course and subsequent practical training. A total of 113 accounting students from six Malaysian universities participated in a longitudinal study…

  1. Effects of Team and Organizational Commitment--A Longitudinal Study

    Science.gov (United States)

    Neininger, Alexandra; Lehmann-Willenbrock, Nale; Kauffeld, Simone; Henschel, Angela

    2010-01-01

    Retention management, i.e., keeping qualified employees, is a top priority for contemporary organizations. Commitment, and especially team commitment, can be the key to mastering this challenge. There is a lack of longitudinal research concerning the development and the direction of the effects of team commitment over time. In a longitudinal…

  2. Use of social media by Western European hospitals: longitudinal study.

    Science.gov (United States)

    Van de Belt, Tom H; Berben, Sivera A A; Samsom, Melvin; Engelen, Lucien J L P G; Schoonhoven, Lisette

    2012-05-01

    Patients increasingly use social media to communicate. Their stories could support quality improvements in participatory health care and could support patient-centered care. Active use of social media by health care institutions could also speed up communication and information provision to patients and their families, thus increasing quality even more. Hospitals seem to be becoming aware of the benefits social media could offer. Data from the United States show that hospitals increasingly use social media, but it is unknown whether and how Western European hospitals use social media. To identify to what extent Western European hospitals use social media. In this longitudinal study, we explored the use of social media by hospitals in 12 Western European countries through an Internet search. We collected data for each country during the following three time periods: April to August 2009, August to December 2010, and April to July 2011. We included 873 hospitals from 12 Western European countries, of which 732 were general hospitals and 141 were university hospitals. The number of included hospitals per country ranged from 6 in Luxembourg to 347 in Germany. We found hospitals using social media in all countries. The use of social media increased significantly over time, especially for YouTube (n = 19, 2% to n = 172, 19.7%), LinkedIn (n =179, 20.5% to n = 278, 31.8%), and Facebook (n = 85, 10% to n = 585, 67.0%). Differences in social media usage between the included countries were significant. Social media awareness in Western European hospitals is growing, as well as its use. Social media usage differs significantly between countries. Except for the Netherlands and the United Kingdom, the group of hospitals that is using social media remains small. Usage of LinkedIn for recruitment shows the awareness of the potential of social media. Future research is needed to investigate how social media lead to improved health care.

  3. Electronic cigarette: a longitudinal study of regular vapers.

    Science.gov (United States)

    Etter, Jean-François

    2017-06-07

    It is unclear how vaping behaviour changes over time in regular vapers, and what occurs when vapers relapse to smoking or when they stop vaping. We assessed change in vaping and smoking behaviours over 12 months in regular vapers. A longitudinal study of 3868 regular vapers enrolled on the Internet in 2012-2015 ("baseline"), followed after one (n=1631, 42%), three (n=1337, 35%), six (n=1148, 30%) and 12 months (n=893, 23%). Participants had been vaping for a median of five months at baseline. Most (77%) were former smokers, who had not smoked for a median of three months at baseline. Over 12 months, enjoyment gradually became the most frequently cited reason to vape (93%), and vaping to deal with craving for tobacco gradually decreased (from 87% to 56%). In exclusive vapers (ex-smokers), nicotine concentration in e-liquids decreased over time (from 12 to 9 mg/mL), but puffs/day remained stable (200 puffs/day). After 12 months, 9% of 687 former smokers relapsed to smoking and 28% of 64 daily smokers (dual users) stopped smoking. After 12 months, when participants stopped vaping, they tended to relapse to smoking (+18% daily smokers among those who stopped vaping versus -2% in permanent vapers, preasons to vape. Rates of relapse to smoking were low in former smokers and quit rates were high in current smokers. Stopping vaping was associated with relapsing to smoking. Even in established vapers, vaping behaviour and reasons to vape change over time. This should be taken into account by clinicians, manufacturers and regulators. Results from this non-representative sample can help generate hypotheses that can later be tested in representative samples of vapers. © The Author 2017. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Holocaust survivors in old age: the Jerusalem Longitudinal Study.

    Science.gov (United States)

    Stessman, Jochanan; Stesssman, Jochanan; Cohen, Aaron; Hammerman-Rozenberg, Robert; Bursztyn, Michael; Azoulay, Daniel; Maaravi, Yoram; Jacobs, Jeremy M

    2008-03-01

    To examine the hypothesis that Holocaust exposure during young adulthood negatively affects physical aging, causing greater morbidity, faster deterioration in health parameters, and shorter survival. A longitudinal cohort study of the natural history of an age-homogenous representative sample born in 1920/21 and living in Jerusalem. Community-based home assessments. Four hundred fifty-eight subjects of European origin aged 70 at baseline and 77 at follow-up. Comprehensive assessment of physical, functional, and psychosocial domains; biographical history of concentration camp internment (Camp), exposure to Nazi occupation during World War II (Exposure), or lack thereof (Controls); and 7-year mortality data from the National Death Registry. Holocaust survivors of the Camp (n=93) and Exposure (n=129) groups were more likely than Controls (n=236) to be male and less educated and have less social support (P=.01), less physical activity (P=.03), greater difficulty in basic activities of daily living (P=.009), poorer self-rated health (P=.04), and greater usage of psychiatric medication (P=.008). No other differences in health parameters or physical illnesses were found. Holocaust survivors had similar rates of deterioration in health and illness parameters over the follow-up period, and 7-year mortality rates were identical. Proportional hazard models showed that being an elderly Holocaust survivor was not predictive of greater 7-year mortality. Fifty years after their Holocaust trauma, survivors still displayed significant psychosocial and functional impairment, although no evidence was found to support the hypothesis that the delayed effects of the trauma of the Holocaust negatively influence physical health, health trajectories, or mortality.

  5. Prediction in Child Development: A Longitudinal Study of Adoptive and Nonadoptive Families. The Delaware Family Study.

    Science.gov (United States)

    Hoopes, Janet L.

    A longitudinal study was conducted to determine factors predicting successful adoptions before placement and to identify differences and similarities between adoptive and biological families. Data collected on both adopted children and on their adoptive families before placement was related to data collected on the same children and families 6…

  6. Stability and change in adult personality over 6 years: findings from the Victoria Longitudinal Study.

    Science.gov (United States)

    Small, Brent J; Hertzog, Christopher; Hultsch, David F; Dixon, Roger A

    2003-05-01

    Data from the Victoria Longitudinal Study were used to examine the 6-year longitudinal stability of personality in older adults. Personality was measured with the NEO Personality Inventory. The longitudinal sample consisted of 223 adults initially ranging from 55 to 85 years of age. Longitudinal confirmatory factor analyses were used to examine the stability of individual differences in change over time, and the stability of the longitudinal factor structure. The results indicated both substantial stability at the level of individual differences in change, as well as significant individual differences in change that were related to age and gender. Finally, the factor structure of personality was invariant over time but did not approximate simple structure for the five dimensions of personality. Our study of 6-year personality development provided both (a). a confirmation of early significant stability findings and (b). unique evidence for significant individual differences in late adulthood.

  7. Longitudinal study of perinatal maternal stress, depressive symptoms and anxiety.

    Science.gov (United States)

    Liou, Shwu-Ru; Wang, Panchalli; Cheng, Ching-Yu

    2014-06-01

    to understand the trends in, and relationships between, maternal stress, depressive symptoms and anxiety in pregnancy and post partum. a prospective longitudinal survey study was undertaken to explore maternal psychological distress throughout the perinatal period. The participants were recruited after 24 completed weeks of gestation, and were followed-up monthly until one month post partum (four surveys in total). participants were recruited from a single hospital in southern Taiwan, and asked to complete questionnaires in the hospital waiting area. inclusion criteria were: age ≥18 years, able to read and write Chinese, ≥24 weeks of gestation, singleton pregnancy and no pregnancy complications (including a diagnosis of antenatal depression or anxiety disorder). In total, 197 women completed all four surveys (response rate 74.62%). stress was measured with the 10-item Perceived Stress Scale, depressive symptoms were measured with the Center for Epidemiologic Studies' Depression scale, and anxiety was measured with the Zung Self-reported Anxiety Scale. Participants were followed-up at four time points: T1 (25-29 gestational weeks), T2 (30-34 gestational weeks), T3 (>34 gestational weeks) and T4 (4-6 weeks post partum). Appointments for data collection were made in accordance with the participants' antenatal and postnatal check-ups. The three types of maternal distress had different courses of change throughout the perinatal period, as levels of depressive symptoms remained unchanged, anxiety levels increased as gestation advanced but declined after birth, and stress decreased gradually during pregnancy but returned to the T1 level after birth. There was a low to high degree of correlation in maternal stress, depressive symptoms and anxiety in pregnancy and post partum. around one-quarter of the study participants had depressive symptoms during pregnancy and post partum. Stress and anxiety showed opposing courses during the perinatal period. Regardless of the

  8. A two-stage biological gas to liquid transfer process to convert carbon dioxide into bioplastic

    KAUST Repository

    Al Rowaihi, Israa; Kick, Benjamin; Grö tzinger, Stefan W.; Burger, Christian; Karan, Ram; Weuster-Botz, Dirk; Eppinger, Jö rg; Arold, Stefan T.

    2018-01-01

    The fermentation of carbon dioxide (CO2) with hydrogen (H2) uses available low-cost gases to synthesis acetic acid. Here, we present a two-stage biological process that allows the gas to liquid transfer (Bio-GTL) of CO2 into the biopolymer

  9. On response time and cycle time distributions in a two-stage cyclic queue

    NARCIS (Netherlands)

    Boxma, O.J.; Donk, P.

    1982-01-01

    We consider a two-stage closed cyclic queueing model. For the case of an exponential server at each queue we derive the joint distribution of the successive response times of a custumer at both queues, using a reversibility argument. This joint distribution turns out to have a product form. The

  10. One-stage and two-stage penile buccal mucosa urethroplasty

    African Journals Online (AJOL)

    G. Barbagli

    2015-12-02

    Dec 2, 2015 ... there also seems to be a trend of decreasing urethritis and an increase of instrumentation and catheter related strictures in these countries as well [4–6]. The repair of penile urethral strictures may require one- or two- stage urethroplasty [7–10]. Certainly, sexual function can be placed at risk by any surgery ...

  11. An Efficient Robust Solution to the Two-Stage Stochastic Unit Commitment Problem

    DEFF Research Database (Denmark)

    Blanco, Ignacio; Morales González, Juan Miguel

    2017-01-01

    This paper proposes a reformulation of the scenario-based two-stage unitcommitment problem under uncertainty that allows finding unit-commitment plansthat perform reasonably well both in expectation and for the worst caserealization of the uncertainties. The proposed reformulation is based onpart...

  12. Design and construction of a two-stage centrifugal pump | Nordiana ...

    African Journals Online (AJOL)

    Centrifugal pumps are widely used in moving liquids from one location to another in homes, offices and industries. Due to the ever increasing demand for centrifugal pumps it became necessary to design and construction of a two-stage centrifugal pump. The pump consisted of an electric motor, a shaft, two rotating impellers ...

  13. Some design aspects of a two-stage rail-to-rail CMOS op amp

    NARCIS (Netherlands)

    Gierkink, Sander L.J.; Holzmann, Peter J.; Wiegerink, Remco J.; Wassenaar, R.F.

    1999-01-01

    A two-stage low-voltage CMOS op amp with rail-to-rail input and output voltage ranges is presented. The circuit uses complementary differential input pairs to achieve the rail-to-rail common-mode input voltage range. The differential pairs operate in strong inversion, and the constant

  14. Insufficient sensitivity of joint aspiration during the two-stage exchange of the hip with spacers.

    Science.gov (United States)

    Boelch, Sebastian Philipp; Weissenberger, Manuel; Spohn, Frederik; Rudert, Maximilian; Luedemann, Martin

    2018-01-10

    Evaluation of infection persistence during the two-stage exchange of the hip is challenging. Joint aspiration before reconstruction is supposed to rule out infection persistence. Sensitivity and specificity of synovial fluid culture and synovial leucocyte count for detecting infection persistence during the two-stage exchange of the hip were evaluated. Ninety-two aspirations before planned joint reconstruction during the two-stage exchange with spacers of the hip were retrospectively analyzed. The sensitivity and specificity of synovial fluid culture was 4.6 and 94.3%. The sensitivity and specificity of synovial leucocyte count at a cut-off value of 2000 cells/μl was 25.0 and 96.9%. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) values were significantly higher before prosthesis removal and reconstruction or spacer exchange (p = 0.00; p = 0.013 and p = 0.039; p = 0.002) in the infection persistence group. Receiver operating characteristic area under the curve values before prosthesis removal and reconstruction or spacer exchange for ESR were lower (0.516 and 0.635) than for CRP (0.720 and 0.671). Synovial fluid culture and leucocyte count cannot rule out infection persistence during the two-stage exchange of the hip.

  15. Two-Stage Power Factor Corrected Power Supplies: The Low Component-Stress Approach

    DEFF Research Database (Denmark)

    Petersen, Lars; Andersen, Michael Andreas E.

    2002-01-01

    The discussion concerning the use of single-stage contra two-stage PFC solutions has been going on for the last decade and it continues. The purpose of this paper is to direct the focus back on how the power is processed and not so much as to the number of stages or the amount of power processed...

  16. A two-stage stochastic programming approach for operating multi-energy systems

    DEFF Research Database (Denmark)

    Zeng, Qing; Fang, Jiakun; Chen, Zhe

    2017-01-01

    This paper provides a two-stage stochastic programming approach for joint operating multi-energy systems under uncertainty. Simulation is carried out in a test system to demonstrate the feasibility and efficiency of the proposed approach. The test energy system includes a gas subsystem with a gas...

  17. EVALUATION OF A TWO-STAGE PASSIVE TREATMENT APPROACH FOR MINING INFLUENCE WATERS

    Science.gov (United States)

    A two-stage passive treatment approach was assessed at bench-scale using two Colorado Mining Influenced Waters (MIWs). The first-stage was a limestone drain with the purpose of removing iron and aluminum and mitigating the potential effects of mineral acidity. The second stage w...

  18. Two-Stage MAS Technique for Analysis of DRA Elements and Arrays on Finite Ground Planes

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2007-01-01

    A two-stage Method of Auxiliary Sources (MAS) technique is proposed for analysis of dielectric resonator antenna (DRA) elements and arrays on finite ground planes (FGPs). The problem is solved by first analysing the DRA on an infinite ground plane (IGP) and then using this solution to model the FGP...

  19. A Two-Stage Approach to Civil Conflict: Contested Incompatibilities and Armed Violence

    DEFF Research Database (Denmark)

    Bartusevicius, Henrikas; Gleditsch, Kristian Skrede

    2017-01-01

    conflict origination but have no clear effect on militarization, whereas other features emphasized as shaping the risk of civil war, such as refugee flows and soft state power, strongly influence militarization but not incompatibilities. We posit that a two-stage approach to conflict analysis can help...

  20. Wide-bandwidth bilateral control using two-stage actuator system

    International Nuclear Information System (INIS)

    Kokuryu, Saori; Izutsu, Masaki; Kamamichi, Norihiro; Ishikawa, Jun

    2015-01-01

    This paper proposes a two-stage actuator system that consists of a coarse actuator driven by a ball screw with an AC motor (the first stage) and a fine actuator driven by a voice coil motor (the second stage). The proposed two-stage actuator system is applied to make a wide-bandwidth bilateral control system without needing expensive high-performance actuators. In the proposed system, the first stage has a wide moving range with a narrow control bandwidth, and the second stage has a narrow moving range with a wide control bandwidth. By consolidating these two inexpensive actuators with different control bandwidths in a complementary manner, a wide bandwidth bilateral control system can be constructed based on a mechanical impedance control. To show the validity of the proposed method, a prototype of the two-stage actuator system has been developed and basic performance was evaluated by experiment. The experimental results showed that a light mechanical impedance with a mass of 10 g and a damping coefficient of 2.5 N/(m/s) that is an important factor to establish good transparency in bilateral control has been successfully achieved and also showed that a better force and position responses between a master and slave is achieved by using the proposed two-stage actuator system compared with a narrow bandwidth case using a single ball screw system. (author)

  1. On A Two-Stage Supply Chain Model In The Manufacturing Industry ...

    African Journals Online (AJOL)

    We model a two-stage supply chain where the upstream stage (stage 2) always meet demand from the downstream stage (stage 1).Demand is stochastic hence shortages will occasionally occur at stage 2. Stage 2 must fill these shortages by expediting using overtime production and/or backordering. We derive optimal ...

  2. Efficiency assessment of wind farms in China using two-stage data envelopment analysis

    International Nuclear Information System (INIS)

    Wu, Yunna; Hu, Yong; Xiao, Xinli; Mao, Chunyu

    2016-01-01

    Highlights: • The efficiency of China’s wind farms is assessed by data envelopment analysis. • Tobit model is used to analyze the impact of uncontrollable factors on efficiency. • Sensitivity analysis is conducted to verify the stability of evaluation results. • Efficiency levels of Chinese wind farms are relatively high in general. • Age and wind curtailment rate negatively affect the productive efficiency. - Abstract: China has been the world’s leader in wind power capacity due to the promotion of favorable policies. Given the rare research on the efficiency of China’s wind farms, this study analyzes the productive efficiency of 42 large-scale wind farms in China using a two-stage analysis. In the first stage, efficiency scores of wind farms are determined with data envelopment analysis and the sensitivity analysis is conducted to verify the robustness of efficiency calculation results. In the second stage, the Tobit regression is employed to explore the relationship between the efficiency scores and the environment variables that are beyond the control of wind farms. According to the results, all wind farms studied operate at an acceptable level. However, 50% of them overinvest in the installed capacity and about 48% have the electricity-saving potential. The most important factors affecting the efficiency of wind farms are the installed capacity and the wind power density. In addition, the age of the wind farm and the wind curtailment rate have a negative effect on productive efficiency, whereas the ownership of the wind farm has no significant effect. Findings from this study may be helpful for stakeholders in the wind industry to select wind power projects, optimize operational strategies and make related policies.

  3. Longitudinal patterns and predictors of multiple health risk behaviors among adolescents : the TRAILS study

    NARCIS (Netherlands)

    Visser, Leenke; de Winter, Andrea F.; Verhulst, Frank C.; Vollebergh, Wilma A.M.; Reijneveld, Sijmen A.

    BACKGROUND: Most studies on multiple health risk behaviors among adolescents have cross-sectionally studied a limited number of health behaviors or determinants. PURPOSE: To examine the prevalence, longitudinal patterns and predictors of individual and multiple health risk behaviors among

  4. Efficiency of primary care in rural Burkina Faso. A two-stage DEA analysis.

    Science.gov (United States)

    Marschall, Paul; Flessa, Steffen

    2011-07-20

    Providing health care services in Africa is hampered by severe scarcity of personnel, medical supplies and financial funds. Consequently, managers of health care institutions are called to measure and improve the efficiency of their facilities in order to provide the best possible services with their resources. However, very little is known about the efficiency of health care facilities in Africa and instruments of performance measurement are hardly applied in this context. This study determines the relative efficiency of primary care facilities in Nouna, a rural health district in Burkina Faso. Furthermore, it analyses the factors influencing the efficiency of these institutions. We apply a two-stage Data Envelopment Analysis (DEA) based on data from a comprehensive provider and household information system. In the first stage, the relative efficiency of each institution is calculated by a traditional DEA model. In the second stage, we identify the reasons for being inefficient by regression technique. The DEA projections suggest that inefficiency is mainly a result of poor utilization of health care facilities as they were either too big or the demand was too low. Regression results showed that distance is an important factor influencing the efficiency of a health care institution Compared to the findings of existing one-stage DEA analyses of health facilities in Africa, the share of relatively efficient units is slightly higher. The difference might be explained by a rather homogenous structure of the primary care facilities in the Burkina Faso sample. The study also indicates that improving the accessibility of primary care facilities will have a major impact on the efficiency of these institutions. Thus, health decision-makers are called to overcome the demand-side barriers in accessing health care.

  5. Two-Stage Multi-Objective Collaborative Scheduling for Wind Farm and Battery Switch Station

    Directory of Open Access Journals (Sweden)

    Zhe Jiang

    2016-10-01

    Full Text Available In order to deal with the uncertainties of wind power, wind farm and electric vehicle (EV battery switch station (BSS were proposed to work together as an integrated system. In this paper, the collaborative scheduling problems of such a system were studied. Considering the features of the integrated system, three indices, which include battery swapping demand curtailment of BSS, wind curtailment of wind farm, and generation schedule tracking of the integrated system are proposed. In addition, a two-stage multi-objective collaborative scheduling model was designed. In the first stage, a day-ahead model was built based on the theory of dependent chance programming. With the aim of maximizing the realization probabilities of these three operating indices, random fluctuations of wind power and battery switch demand were taken into account simultaneously. In order to explore the capability of BSS as reserve, the readjustment process of the BSS within each hour was considered in this stage. In addition, the stored energy rather than the charging/discharging power of BSS during each period was optimized, which will provide basis for hour-ahead further correction of BSS. In the second stage, an hour-ahead model was established. In order to cope with the randomness of wind power and battery swapping demand, the proposed hour-ahead model utilized ultra-short term prediction of the wind power and the battery switch demand to schedule the charging/discharging power of BSS in a rolling manner. Finally, the effectiveness of the proposed models was validated by case studies. The simulation results indicated that the proposed model could realize complement between wind farm and BSS, reduce the dependence on power grid, and facilitate the accommodation of wind power.

  6. Optimization of a two stage process for biodiesel production from shea butter using response surface methodology

    Directory of Open Access Journals (Sweden)

    E.O. Ajala

    2017-12-01

    Full Text Available The challenges of biodiesel production from high free fatty acid (FFA shea butter (SB necessitated this study. The reduction of %FFA of SB by esterification and its subsequent utilization by transesterification for biodiesel production in a two stage process for optimization studies was investigated using response surface methodology based on a central composite design (CCD. Four operating conditions were investigated to reduce the %FFA of SB and increase the %yield of shea biodiesel (SBD. The operating conditions were temperature (40–60°C, agitation speed (200–1400 rpm, methanol (MeOH: oil mole ratio: 2:1–6:1 (w/w for esterification and 4:1–8:1 (w/w for transesterification and catalyst loading: 1–2% (H2SO4, (v/v for esterification and KOH, (w/w for transesterification. The significance of the parameters obtained in linear and non-linear form from the models were determined using analysis of variance (ANOVA. The optimal operating conditions that gave minimum FFA of 0.26% were 52.19°C, 200 rpm, 2:1 (w/w and 1.5% (v/v, while those that gave maximum yield of 92.16% SBD were 40°C, 800 rpm, 7:1 (w/w and 1% (w/w. The p-value of <0.0001 for each of the stages showed that the models were significant with R2 of 0.96 each. These results indicate the reproducibility of the models and showed that the RSM is suitable to optimize the esterification and transesterification of SB for SBD production. Therefore, RSM is a useful tool that can be employed in industrial scale production of SBD from high FFA SB.

  7. Neuroscience and approach/avoidance personality traits: a two stage (valuation-motivation) approach.

    Science.gov (United States)

    Corr, Philip J; McNaughton, Neil

    2012-11-01

    Many personality theories link specific traits to the sensitivities of the neural systems that control approach and avoidance. But there is no consensus on the nature of these systems. Here we combine recent advances in economics and neuroscience to provide a more solid foundation for a neuroscience of approach/avoidance personality. We propose a two-stage integration of valuation (loss/gain) sensitivities with motivational (approach/avoidance/conflict) sensitivities. Our key conclusions are: (1) that valuation of appetitive and aversive events (e.g. gain and loss as studied by behavioural economists) is an independent perceptual input stage--with the economic phenomenon of loss aversion resulting from greater negative valuation sensitivity compared to positive valuation sensitivity; (2) that valuation of an appetitive stimulus then interacts with a contingency of presentation or omission to generate a motivational 'attractor' or 'repulsor', respectively (vice versa for an aversive stimulus); (3) the resultant behavioural tendencies to approach or avoid have distinct sensitivities to those of the valuation systems; (4) while attractors and repulsors can reinforce new responses they also, more usually, elicit innate or previously conditioned responses and so the perception/valuation-motivation/action complex is best characterised as acting as a 'reinforcer' not a 'reinforcement'; and (5) approach-avoidance conflict must be viewed as activating a third motivation system that is distinct from the basic approach and avoidance systems. We provide examples of methods of assessing each of the constructs within approach-avoidance theories and of linking these constructs to personality measures. We sketch a preliminary five-element reinforcer sensitivity theory (RST-5) as a first step in the integration of existing specific approach-avoidance theories into a coherent neuroscience of personality. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Neural mechanisms of human perceptual learning: electrophysiological evidence for a two-stage process.

    Science.gov (United States)

    Hamamé, Carlos M; Cosmelli, Diego; Henriquez, Rodrigo; Aboitiz, Francisco

    2011-04-26

    Humans and other animals change the way they perceive the world due to experience. This process has been labeled as perceptual learning, and implies that adult nervous systems can adaptively modify the way in which they process sensory stimulation. However, the mechanisms by which the brain modifies this capacity have not been sufficiently analyzed. We studied the neural mechanisms of human perceptual learning by combining electroencephalographic (EEG) recordings of brain activity and the assessment of psychophysical performance during training in a visual search task. All participants improved their perceptual performance as reflected by an increase in sensitivity (d') and a decrease in reaction time. The EEG signal was acquired throughout the entire experiment revealing amplitude increments, specific and unspecific to the trained stimulus, in event-related potential (ERP) components N2pc and P3 respectively. P3 unspecific modification can be related to context or task-based learning, while N2pc may be reflecting a more specific attentional-related boosting of target detection. Moreover, bell and U-shaped profiles of oscillatory brain activity in gamma (30-60 Hz) and alpha (8-14 Hz) frequency bands may suggest the existence of two phases for learning acquisition, which can be understood as distinctive optimization mechanisms in stimulus processing. We conclude that there are reorganizations in several neural processes that contribute differently to perceptual learning in a visual search task. We propose an integrative model of neural activity reorganization, whereby perceptual learning takes place as a two-stage phenomenon including perceptual, attentional and contextual processes.

  9. Influence of Cu(NO32 initiation additive in two-stage mode conditions of coal pyrolytic decomposition

    Directory of Open Access Journals (Sweden)

    Larionov Kirill

    2017-01-01

    Full Text Available Two-stage process (pyrolysis and oxidation of brown coal sample with Cu(NO32 additive pyrolytic decomposition was studied. Additive was introduced by using capillary wetness impregnation method with 5% mass concentration. Sample reactivity was studied by thermogravimetric analysis with staged gaseous medium supply (argon and air at heating rate 10 °C/min and intermediate isothermal soaking. The initiative additive introduction was found to significantly reduce volatile release temperature and accelerate thermal decomposition of sample. Mass-spectral analysis results reveal that significant difference in process characteristics is connected to volatile matter release stage which is initiated by nitrous oxide produced during copper nitrate decomposition.

  10. Mathematics, Language, and Learning: A Longitudinal Study of Elementary Teachers and Their Mathematics Teaching Practices

    OpenAIRE

    Yeh, Cathery

    2016-01-01

    Elementary school mathematics has gained increased attention in the last few decades. A growing field of research has studied the programmatic design and development of elementary mathematics teaching in teacher education, however, few studies have examined longitudinally the mathematics teaching of novice elementary teachers. Existing longitudinal studies on elementary mathematics teaching have generally focused on the effects of teacher preparation on their beginning practices and have exam...

  11. CFD simulations of compressed air two stage rotary Wankel expander – Parametric analysis

    International Nuclear Information System (INIS)

    Sadiq, Ghada A.; Tozer, Gavin; Al-Dadah, Raya; Mahmoud, Saad

    2017-01-01

    Highlights: • CFD ANSYS-Fluent 3D simulation of Wankel expander is developed. • Single and two-stage expander’s performance is compared. • Inlet and outlet ports shape and configurations are investigated. • Isentropic efficiency of two stage Wankel expander of 91% is achieved. - Abstract: A small scale volumetric Wankel expander is a powerful device for small-scale power generation in compressed air energy storage (CAES) systems and Organic Rankine cycles powered by different heat sources such as, biomass, low temperature geothermal, solar and waste heat leading to significant reduction in CO_2 emissions. Wankel expanders outperform other types of expander due to their ability to produce two power pulses per revolution per chamber additional to higher compactness, lower noise and vibration and lower cost. In this paper, a computational fluid dynamics (CFD) model was developed using ANSYS 16.2 to simulate the flow dynamics for a single and two stage Wankel expanders and to investigate the effect of port configurations, including size and spacing, on the expander’s power output and isentropic efficiency. Also, single-stage and two-stage expanders were analysed with different operating conditions. Single-stage 3D CFD results were compared to published work showing close agreement. The CFD modelling was used to investigate the performance of the rotary device using air as an ideal gas with various port diameters ranging from 15 mm to 50 mm; port spacing varying from 28 mm to 66 mm; different Wankel expander sizes (r = 48, e = 6.6, b = 32) mm and (r = 58, e = 8, b = 40) mm both as single-stage and as two-stage expanders with different configurations and various operating conditions. Results showed that the best Wankel expander design for a single-stage was (r = 48, e = 6.6, b = 32) mm, with the port diameters 20 mm and port spacing equal to 50 mm. Moreover, combining two Wankel expanders horizontally, with a larger one at front, produced 8.52 kW compared

  12. Personality factors and breast cancer development: a prospective longitudinal study.

    Science.gov (United States)

    Bleiker, E M; van der Ploeg, H M; Hendriks, J H; Adèr, H J

    1996-10-16

    It has been estimated that approximately 25% of all breast cancers in women can be explained by currently recognized somatic (i.e., hereditary and physiologic) risk factors. It has also been hypothesized that psychological factors may play a role in the development of breast cancer. We investigated the extent to which personality factors, in addition to somatic risk factors, may be associated with the development of primary breast cancer. We employed a prospective, longitudinal study design. From 1989 through 1990, a personality questionnaire was sent to all female residents of the Dutch city of Nijmegen who were 43 years of age or older. This questionnaire was sent as part of an invitation to participate in a population-based breast cancer screening program. Women who developed breast cancer among those who returned completed questionnaires were compared with women without such a diagnosis in regard to somatic risk factors and personality traits, including anxiety, anger, depression, rationality, anti-emotionality (i.e., an absence of emotional behavior or a lack of trust in one's own feelings), understanding, optimism, social support, and the expression and control of emotions. Conditional logistic regression analysis was used to identify variables that could best explain group membership (i.e., belonging to the case [breast cancer] or the control [without disease] group). Personality questionnaires were sent to 28 940 women, and 9705 (34%) were returned in such a way that they could be used for statistical analyses. Among the 9705 women who returned useable questionnaires, 131 were diagnosed with breast cancer during the period from 1989 through 1994. Seven hundred seventy-one age-matched control subjects (up to six per case patient) were selected for the analyses. Three variables were found to be statistically significantly associated with an increased risk of breast cancer: 1) having a first-degree family member with breast cancer (versus not having an

  13. A Longitudinal Study of the Role of T Cell subset, Th1/Th2 cytokines ...

    African Journals Online (AJOL)

    A Longitudinal Study of the Role of T Cell subset, Th1/Th2 cytokines and antiplasmodial antibodies in uncomplicated Malaria in a Village Population Chronically Exposed to Plasmodium falciparum Malaria.

  14. Sports participation and psychosocial health : a longitudinal observational study in children

    NARCIS (Netherlands)

    Moeijes, Janet; van Busschbach, Jooske T; Bosscher, Ruud J; Twisk, Jos W R

    2018-01-01

    BACKGROUND: It is well known that sports participation is positively associated with psychosocial health in children, but details about this association over time are lacking. This study aimed to explore longitudinal associations between several characteristics of sports participation and three

  15. A longitudinal study of the effects of television viewing on aggressive and prosocial behaviours

    NARCIS (Netherlands)

    Wiegman, O.; Kuttschreuter, M.; Baarda, B.

    1992-01-01

    A longitudinal study investigated the extent to which children's exposure to aggressive and prosocial television models in drama programmes influences their aggressive and prosocial behaviour. In The Netherlands we did not find significant positive correlations between prosocial behaviour and the

  16. Wealth Distribution and Mobility in Denmark: a Longitudinal Study

    DEFF Research Database (Denmark)

    Bentzen, Jan Børsen; Schmidt-Sørensen, Jan Beyer

    1994-01-01

    We describe and analyse wealth mobility in a national sample of 32,675 individuals from the Danish Longitudinal Database over the period from 1983 to 1990. A transition matrix, the Shorrocks measure, average decile position for various subgroups, and wealth in 1990 compared with wealth in 1983...... are used to describe patterns of wealth mobility. These results and regression models of change in percentile position identify winners and losers. The losers include students, singles with children, those who changed residence and those who experienced unemployment, while the winners were the houseowners...

  17. Self-stigma and suicidality: a longitudinal study.

    Science.gov (United States)

    Oexle, Nathalie; Rüsch, Nicolas; Viering, Sandra; Wyss, Christine; Seifritz, Erich; Xu, Ziyan; Kawohl, Wolfram

    2017-06-01

    Mental illness stigma is a source of distress for persons with mental illness. Self-stigma occurs when negative stereotypes are internalized, leading to low self-esteem, shame and hopelessness. Due to its consequences self-stigma may contribute to suicidality and be a modifiable target for suicide prevention. Based on 222 disability pensioners with mental illness we examined whether self-stigma at baseline is associated with suicidal ideation over a 2-year period, controlling for baseline suicidal ideation, symptoms, age and gender. More self-stigma predicted suicidal ideation at baseline and longitudinally. Interventions on different levels to reduce self-stigma could improve suicide prevention.

  18. Psychological predictors of eco-driving: A longitudinal study

    OpenAIRE

    Lauper Elisabeth; Moser Stephanie; Fischer Maja; Matthies Ellen; Kaufmann-Hayoz Ruth

    2015-01-01

    Eco-driving has well-known positive effects on fuel economy and greenhouse-gas emissions. Moreover, eco-driving reduces road-traffic noise, which is a serious threat to the health and well-being of many people. We investigated the psychological predictors of the adoption of eco-driving from the perspective of road-traffic noise abatement. The data came from 890 car drivers who participated in a longitudinal survey over four months. Specifically, we tested the effects of the intention to preve...

  19. Trajectories of Mental Health over 16 Years amongst Young Adult Women: The Australian Longitudinal Study on Women's Health

    Science.gov (United States)

    Holden, Libby; Ware, Robert S.; Lee, Christina

    2016-01-01

    This article used data from 5,171 young women participating in the Australian Longitudinal Study on Women's Health, a nationally representative longitudinal cohort study, to identify longitudinal trajectory patterns of mental health across 6 surveys over 16 years of early adulthood, from age 18-23 to age 34-39. In addition, we identified both…

  20. Development of Food Functions and Production Process for Onion Vinegar Using a Two-Stage Continuous-Tank Reactor

    OpenAIRE

    小林, 秀彰; 山口, 文; 富田, 弘毅; 中井, 義昭; 管野, 亨; 小林, 正義; KOBAYASHI, Hideaki; YAMAGUCHI, Kazaru; TOMITA, Koki; NAKAI, Yoshiaki; KANNO, Tohru; KOBAYASHI, Masayoshi

    1998-01-01

    A two-stage continuous-tank reactor was developed to optimize the production of onion vinegar, and the onion vinegar produced was studied to determine its benefits for human health. The ”Silan ring” porous ceramics support was available to immobilize microorganisms, maintain higher mechanical strength and provide a stable rate of alcohol production even at higher dilution rates than 1.2 hr^, without wash-out. The forced cyclic operation of reaction temperature yielded an increase of 25% for ...

  1. A longitudinal study of multidimensional performance characteristics related to physical capacities in youth handball.

    Science.gov (United States)

    Matthys, Stijn P J; Vaeyens, Roel; Fransen, Job; Deprez, Dieter; Pion, Johan; Vandendriessche, Joric; Vandorpe, Barbara; Lenoir, Matthieu; Philippaerts, Renaat

    2013-01-01

    Longitudinal research provides valuable information about change and progress towards elite performance. Unfortunately, there is a lack of longitudinal research in handball. In this study, 94 youth handball players (oldest group: n = 41; age 15-17 and youngest group: n = 53; age 13-15) were followed over a three-year period. Repeated measures ANCOVA was conducted to reveal longitudinal changes in anthropometry and physical performance between elite and non-elite players, controlling for maturation. Maturation effects were found for anthropometry (P team handball should recognise the importance of good skills and an excellent endurance for talent identification purposes.

  2. [Information management in multicenter studies: the Brazilian longitudinal study for adult health].

    Science.gov (United States)

    Duncan, Bruce Bartholow; Vigo, Álvaro; Hernandez, Émerson; Luft, Vivian Cristine; Ahlert, Hubert; Bergmann, Kaiser; Mota, Eduardo

    2013-06-01

    Information management in large multicenter studies requires a specialized approach. The Estudo Longitudinal da Saúde do Adulto (ELSA-Brasil - Brazilian Longitudinal Study for Adult Health) has created a Datacenter to enter and manage its data system. The aim of this paper is to describe the steps involved, including the information entry, transmission and management methods. A web system was developed in order to allow, in a safe and confidential way, online data entry, checking and editing, as well as the incorporation of data collected on paper. Additionally, a Picture Archiving and Communication System was implemented and customized for echocardiography and retinography. It stores the images received from the Investigation Centers and makes them available at the Reading Centers. Finally, data extraction and cleaning processes were developed to create databases in formats that enable analyses in multiple statistical packages.

  3. A Two-stage Improvement Method for Robot Based 3D Surface Scanning

    Science.gov (United States)

    He, F. B.; Liang, Y. D.; Wang, R. F.; Lin, Y. S.

    2018-03-01

    As known that the surface of unknown object was difficult to measure or recognize precisely, hence the 3D laser scanning technology was introduced and used properly in surface reconstruction. Usually, the surface scanning speed was slower and the scanning quality would be better, while the speed was faster and the quality would be worse. In this case, the paper presented a new two-stage scanning method in order to pursuit the quality of surface scanning in a faster speed. The first stage was rough scanning to get general point cloud data of object’s surface, and then the second stage was specific scanning to repair missing regions which were determined by chord length discrete method. Meanwhile, a system containing a robotic manipulator and a handy scanner was also developed to implement the two-stage scanning method, and relevant paths were planned according to minimum enclosing ball and regional coverage theories.

  4. Target tracking system based on preliminary and precise two-stage compound cameras

    Science.gov (United States)

    Shen, Yiyan; Hu, Ruolan; She, Jun; Luo, Yiming; Zhou, Jie

    2018-02-01

    Early detection of goals and high-precision of target tracking is two important performance indicators which need to be balanced in actual target search tracking system. This paper proposed a target tracking system with preliminary and precise two - stage compound. This system using a large field of view to achieve the target search. After the target was searched and confirmed, switch into a small field of view for two field of view target tracking. In this system, an appropriate filed switching strategy is the key to achieve tracking. At the same time, two groups PID parameters are add into the system to reduce tracking error. This combination way with preliminary and precise two-stage compound can extend the scope of the target and improve the target tracking accuracy and this method has practical value.

  5. A Two Stage Solution Procedure for Production Planning System with Advance Demand Information

    Science.gov (United States)

    Ueno, Nobuyuki; Kadomoto, Kiyotaka; Hasuike, Takashi; Okuhara, Koji

    We model for ‘Naiji System’ which is a unique corporation technique between a manufacturer and suppliers in Japan. We propose a two stage solution procedure for a production planning problem with advance demand information, which is called ‘Naiji’. Under demand uncertainty, this model is formulated as a nonlinear stochastic programming problem which minimizes the sum of production cost and inventory holding cost subject to a probabilistic constraint and some linear production constraints. By the convexity and the special structure of correlation matrix in the problem where inventory for different periods is not independent, we propose a solution procedure with two stages which are named Mass Customization Production Planning & Management System (MCPS) and Variable Mesh Neighborhood Search (VMNS) based on meta-heuristics. It is shown that the proposed solution procedure is available to get a near optimal solution efficiently and practical for making a good master production schedule in the suppliers.

  6. A simple two stage optimization algorithm for constrained power economic dispatch

    International Nuclear Information System (INIS)

    Huang, G.; Song, K.

    1994-01-01

    A simple two stage optimization algorithm is proposed and investigated for fast computation of constrained power economic dispatch control problems. The method is a simple demonstration of the hierarchical aggregation-disaggregation (HAD) concept. The algorithm first solves an aggregated problem to obtain an initial solution. This aggregated problem turns out to be classical economic dispatch formulation, and it can be solved in 1% of overall computation time. In the second stage, linear programming method finds optimal solution which satisfies power balance constraints, generation and transmission inequality constraints and security constraints. Implementation of the algorithm for IEEE systems and EPRI Scenario systems shows that the two stage method obtains average speedup ratio 10.64 as compared to classical LP-based method

  7. A Sensorless Power Reserve Control Strategy for Two-Stage Grid-Connected PV Systems

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

    2017-01-01

    Due to the still increasing penetration of grid-connected Photovoltaic (PV) systems, advanced active power control functionalities have been introduced in grid regulations. A power reserve control, where namely the active power from the PV panels is reserved during operation, is required for grid...... support. In this paper, a cost-effective solution to realize the power reserve for two-stage grid-connected PV systems is proposed. The proposed solution routinely employs a Maximum Power Point Tracking (MPPT) control to estimate the available PV power and a Constant Power Generation (CPG) control...... performed on a 3-kW two-stage single-phase grid-connected PV system, where the power reserve control is achieved upon demands....

  8. A two staged condensation of vapors of an isobutane tower in installations for sulfuric acid alkylation

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, N.P.; Feyzkhanov, R.I.; Idrisov, A.D.; Navalikhin, P.G.; Sakharov, V.D.

    1983-01-01

    In order to increase the concentration of isobutane to greater than 72 to 76 percent in an installation for sulfuric acid alkylation, a system of two staged condensation of vapors from an isobutane tower is placed into operation. The first stage condenses the heavier part of the upper distillate of the tower, which is achieved through somewhat of an increase in the condensate temperature. The product which is condensed in the first stage is completely returned to the tower as a live irrigation. The vapors of the isobutane fraction which did not condense in the first stage are sent to two newly installed condensers, from which the product after condensation passes through intermediate tanks to further depropanization. The two staged condensation of vapors of the isobutane tower reduces the content of the inert diluents, the propane and n-butane in the upper distillate of the isobutane tower and creates more favorable conditions for the operation of the isobutane and propane tower.

  9. Optimising the refrigeration cycle with a two-stage centrifugal compressor and a flash intercooler

    Energy Technology Data Exchange (ETDEWEB)

    Roeyttae, Pekka; Turunen-Saaresti, Teemu; Honkatukia, Juha [Lappeenranta University of Technology, Laboratory of Energy and Environmental Technology, PO Box 20, 53851 Lappeenranta (Finland)

    2009-09-15

    The optimisation of a refrigeration process with a two-stage centrifugal compressor and flash intercooler is presented in this paper. The two-stage centrifugal compressor stages are on the same shaft and the electric motor is cooled with the refrigerant. The performance of the centrifugal compressor is evaluated based on semi-empirical specific-speed curves and the effect of the Reynolds number, surface roughness and tip clearance have also been taken into account. The thermodynamic and transport properties of the working fluids are modelled with a real-gas model. The condensing and evaporation temperatures, the temperature after the flash intercooler, and cooling power have been chosen as fixed values in the process. The aim is to gain a maximum coefficient of performance (COP). The method of optimisation, the operation of the compressor and flash intercooler, and the method for estimating the electric motor cooling are also discussed in the article. (author)

  10. A Two-Stage Queue Model to Optimize Layout of Urban Drainage System considering Extreme Rainstorms

    OpenAIRE

    He, Xinhua; Hu, Wenfa

    2017-01-01

    Extreme rainstorm is a main factor to cause urban floods when urban drainage system cannot discharge stormwater successfully. This paper investigates distribution feature of rainstorms and draining process of urban drainage systems and uses a two-stage single-counter queue method M/M/1→M/D/1 to model urban drainage system. The model emphasizes randomness of extreme rainstorms, fuzziness of draining process, and construction and operation cost of drainage system. Its two objectives are total c...

  11. Generation of dense, pulsed beams of refractory metal atoms using two-stage laser ablation

    International Nuclear Information System (INIS)

    Kadar-Kallen, M.A.; Bonin, K.D.

    1994-01-01

    We report a technique for generating a dense, pulsed beam of refractory metal atoms using two-stage laser ablation. An atomic beam of uranium was produced with a peak, ground-state number density of 1x10 12 cm -3 at a distance of z=27 cm from the source. This density can be scaled as 1/z 3 to estimate the density at other distances which are also far from the source

  12. Single-stage-to-orbit versus two-stage-two-orbit: A cost perspective

    Science.gov (United States)

    Hamaker, Joseph W.

    1996-03-01

    This paper considers the possible life-cycle costs of single-stage-to-orbit (SSTO) and two-stage-to-orbit (TSTO) reusable launch vehicles (RLV's). The analysis parametrically addresses the issue such that the preferred economic choice comes down to the relative complexity of the TSTO compared to the SSTO. The analysis defines the boundary complexity conditions at which the two configurations have equal life-cycle costs, and finally, makes a case for the economic preference of SSTO over TSTO.

  13. Control strategy research of two stage topology for pulsed power supply

    International Nuclear Information System (INIS)

    Shi Chunfeng; Wang Rongkun; Huang Yuzhen; Chen Youxin; Yan Hongbin; Gao Daqing

    2013-01-01

    A kind of pulsed power supply of HIRFL-CSR was introduced, the ripple and the current error of the topological structure of the power in the operation process were analyzed, and two stage topology of pulsed power supply was given. The control strategy was simulated and the experiment was done in digital power platform. The results show that the main circuit structure and control method are feasible. (authors)

  14. A novel flow sensor based on resonant sensing with two-stage microleverage mechanism

    Science.gov (United States)

    Yang, B.; Guo, X.; Wang, Q. H.; Lu, C. F.; Hu, D.

    2018-04-01

    The design, simulation, fabrication, and experiments of a novel flow sensor based on resonant sensing with a two-stage microleverage mechanism are presented in this paper. Different from the conventional detection methods for flow sensors, two differential resonators are adopted to implement air flow rate transformation through two-stage leverage magnification. The proposed flow sensor has a high sensitivity since the adopted two-stage microleverage mechanism possesses a higher amplification factor than a single-stage microleverage mechanism. The modal distribution and geometric dimension of the two-stage leverage mechanism and hair are analyzed and optimized by Ansys simulation. A digital closed-loop driving technique with a phase frequency detector-based coordinate rotation digital computer algorithm is implemented for the detection and locking of resonance frequency. The sensor fabricated by the standard deep dry silicon on a glass process has a device dimension of 5100 μm (length) × 5100 μm (width) × 100 μm (height) with a hair diameter of 1000 μm. The preliminary experimental results demonstrate that the maximal mechanical sensitivity of the flow sensor is approximately 7.41 Hz/(m/s)2 at a resonant frequency of 22 kHz for the hair height of 9 mm and increases by 2.42 times as hair height extends from 3 mm to 9 mm. Simultaneously, a detection-limit of 3.23 mm/s air flow amplitude at 60 Hz is confirmed. The proposed flow sensor has great application prospects in the micro-autonomous system and technology, self-stabilizing micro-air vehicles, and environmental monitoring.

  15. Two Stage Fuzzy Methodology to Evaluate the Credit Risks of Investment Projects

    OpenAIRE

    O. Badagadze; G. Sirbiladze; I. Khutsishvili

    2014-01-01

    The work proposes a decision support methodology for the credit risk minimization in selection of investment projects. The methodology provides two stages of projects’ evaluation. Preliminary selection of projects with minor credit risks is made using the Expertons Method. The second stage makes ranking of chosen projects using the Possibilistic Discrimination Analysis Method. The latter is a new modification of a well-known Method of Fuzzy Discrimination Analysis.

  16. A Two-Stage Rural Household Demand Analysis: Microdata Evidence from Jiangsu Province, China

    OpenAIRE

    X.M. Gao; Eric J. Wailes; Gail L. Cramer

    1996-01-01

    In this paper we evaluate economic and demographic effects on China's rural household demand for nine food commodities: vegetables, pork, beef and lamb, poultry, eggs, fish, sugar, fruit, and grain; and five nonfood commodity groups: clothing, fuel, stimulants, housing, and durables. A two-stage budgeting allocation procedure is used to obtain an empirically tractable amalgamative demand system for food commodities which combine an upper-level AIDS model and a lower-level GLES as a modeling f...

  17. Latent Inhibition as a Function of US Intensity in a Two-Stage CER Procedure

    Science.gov (United States)

    Rodriguez, Gabriel; Alonso, Gumersinda

    2004-01-01

    An experiment is reported in which the effect of unconditioned stimulus (US) intensity on latent inhibition (LI) was examined, using a two-stage conditioned emotional response (CER) procedure in rats. A tone was used as the pre-exposed and conditioned stimulus (CS), and a foot-shock of either a low (0.3 mA) or high (0.7 mA) intensity was used as…

  18. Modelling of an air-cooled two-stage Rankine cycle for electricity production

    International Nuclear Information System (INIS)

    Liu, Bo

    2014-01-01

    This work considers a two stage Rankine cycle architecture slightly different from a standard Rankine cycle for electricity generation. Instead of expanding the steam to extremely low pressure, the vapor leaves the turbine at a higher pressure then having a much smaller specific volume. It is thus possible to greatly reduce the size of the steam turbine. The remaining energy is recovered by a bottoming cycle using a working fluid which has a much higher density than the water steam. Thus, the turbines and heat exchangers are more compact; the turbine exhaust velocity loss is lower. This configuration enables to largely reduce the global size of the steam water turbine and facilitate the use of a dry cooling system. The main advantage of such an air cooled two stage Rankine cycle is the possibility to choose the installation site of a large or medium power plant without the need of a large and constantly available water source; in addition, as compared to water cooled cycles, the risk regarding future operations is reduced (climate conditions may affect water availability or temperature, and imply changes in the water supply regulatory rules). The concept has been investigated by EDF R and D. A 22 MW prototype was developed in the 1970's using ammonia as the working fluid of the bottoming cycle for its high density and high latent heat. However, this fluid is toxic. In order to search more suitable working fluids for the two stage Rankine cycle application and to identify the optimal cycle configuration, we have established a working fluid selection methodology. Some potential candidates have been identified. We have evaluated the performances of the two stage Rankine cycles operating with different working fluids in both design and off design conditions. For the most acceptable working fluids, components of the cycle have been sized. The power plant concept can then be evaluated on a life cycle cost basis. (author)

  19. A Sensorless Power Reserve Control Strategy for Two-Stage Grid-Connected PV Systems

    OpenAIRE

    Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

    2017-01-01

    Due to the still increasing penetration of grid-connected Photovoltaic (PV) systems, advanced active power control functionalities have been introduced in grid regulations. A power reserve control, where namely the active power from the PV panels is reserved during operation, is required for grid support. In this paper, a cost-effective solution to realize the power reserve for two-stage grid-connected PV systems is proposed. The proposed solution routinely employs a Maximum Power Point Track...

  20. Actuator Fault Diagnosis in a Boeing 747 Model via Adaptive Modified Two-Stage Kalman Filter

    Directory of Open Access Journals (Sweden)

    Fikret Caliskan

    2014-01-01

    Full Text Available An adaptive modified two-stage linear Kalman filtering algorithm is utilized to identify the loss of control effectiveness and the magnitude of low degree of stuck faults in a closed-loop nonlinear B747 aircraft. Control effectiveness factors and stuck magnitudes are used to quantify faults entering control systems through actuators. Pseudorandom excitation inputs are used to help distinguish partial loss and stuck faults. The partial loss and stuck faults in the stabilizer are isolated and identified successfully.

  1. Two-stage energy storage equalization system for lithium-ion battery pack

    Science.gov (United States)

    Chen, W.; Yang, Z. X.; Dong, G. Q.; Li, Y. B.; He, Q. Y.

    2017-11-01

    How to raise the efficiency of energy storage and maximize storage capacity is a core problem in current energy storage management. For that, two-stage energy storage equalization system which contains two-stage equalization topology and control strategy based on a symmetric multi-winding transformer and DC-DC (direct current-direct current) converter is proposed with bidirectional active equalization theory, in order to realize the objectives of consistent lithium-ion battery packs voltages and cells voltages inside packs by using a method of the Range. Modeling analysis demonstrates that the voltage dispersion of lithium-ion battery packs and cells inside packs can be kept within 2 percent during charging and discharging. Equalization time was 0.5 ms, which shortened equalization time of 33.3 percent compared with DC-DC converter. Therefore, the proposed two-stage lithium-ion battery equalization system can achieve maximum storage capacity between lithium-ion battery packs and cells inside packs, meanwhile efficiency of energy storage is significantly improved.

  2. Production of endo-pectate lyase by two stage cultivation of Erwinia carotovora

    Energy Technology Data Exchange (ETDEWEB)

    Fukuoka, Satoshi; Kobayashi, Yoshiaki

    1987-02-26

    The productivity of endo-pectate lyase from Erwinia carotovora GIR 1044 was found to be greatly improved by two stage cultivation: in the first stage the bacterium was grown with an inducing carbon source, e.g., pectin, and in the second stage it was cultivated with glycerol, xylose, or fructose with the addition of monosodium L-glutamate as nitrogen source. In the two stage cultivation using pectin or glycerol as the carbon source the enzyme activity reached 400 units/ml, almost 3 times as much as that of one stage cultivation in a 10 liter fermentor. Using two stage cultivation in the 200 liter fermentor improved enzyme productivity over that in the 10 liter fermentor, with 500 units/ml of activity. Compared with the cultivation in Erlenmeyer flasks, fermentor cultivation improved enzyme productivity. The optimum cultivating conditions were agitation of 480 rpm with aeration of 0.5 vvm at 28 /sup 0/C. (4 figs, 4 tabs, 14 refs)

  3. A two-stage extraction procedure for insensitive munition (IM) explosive compounds in soils.

    Science.gov (United States)

    Felt, Deborah; Gurtowski, Luke; Nestler, Catherine C; Johnson, Jared; Larson, Steven

    2016-12-01

    The Department of Defense (DoD) is developing a new category of insensitive munitions (IMs) that are more resistant to detonation or promulgation from external stimuli than traditional munition formulations. The new explosive constituent compounds are 2,4-dinitroanisole (DNAN), nitroguanidine (NQ), and nitrotriazolone (NTO). The production and use of IM formulations may result in interaction of IM component compounds with soil. The chemical properties of these IM compounds present unique challenges for extraction from environmental matrices such as soil. A two-stage extraction procedure was developed and tested using several soil types amended with known concentrations of IM compounds. This procedure incorporates both an acidified phase and an organic phase to account for the chemical properties of the IM compounds. The method detection limits (MDLs) for all IM compounds in all soil types were regulatory risk-based Regional Screening Level (RSL) criteria for soil proposed by the U.S. Army Public Health Center. At defined environmentally relevant concentrations, the average recovery of each IM compound in each soil type was consistent and greater than 85%. The two-stage extraction method decreased the influence of soil composition on IM compound recovery. UV analysis of NTO established an isosbestic point based on varied pH at a detection wavelength of 341 nm. The two-stage soil extraction method is equally effective for traditional munition compounds, a potentially important point when examining soils exposed to both traditional and insensitive munitions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Two-stage solar concentrators based on parabolic troughs: asymmetric versus symmetric designs.

    Science.gov (United States)

    Schmitz, Max; Cooper, Thomas; Ambrosetti, Gianluca; Steinfeld, Aldo

    2015-11-20

    While nonimaging concentrators can approach the thermodynamic limit of concentration, they generally suffer from poor compactness when designed for small acceptance angles, e.g., to capture direct solar irradiation. Symmetric two-stage systems utilizing an image-forming primary parabolic concentrator in tandem with a nonimaging secondary concentrator partially overcome this compactness problem, but their achievable concentration ratio is ultimately limited by the central obstruction caused by the secondary. Significant improvements can be realized by two-stage systems having asymmetric cross-sections, particularly for 2D line-focus trough designs. We therefore present a detailed analysis of two-stage line-focus asymmetric concentrators for flat receiver geometries and compare them to their symmetric counterparts. Exemplary designs are examined in terms of the key optical performance metrics, namely, geometric concentration ratio, acceptance angle, concentration-acceptance product, aspect ratio, active area fraction, and average number of reflections. Notably, we show that asymmetric designs can achieve significantly higher overall concentrations and are always more compact than symmetric systems designed for the same concentration ratio. Using this analysis as a basis, we develop novel asymmetric designs, including two-wing and nested configurations, which surpass the optical performance of two-mirror aplanats and are comparable with the best reported 2D simultaneous multiple surface designs for both hollow and dielectric-filled secondaries.

  5. Final Report on Two-Stage Fast Spectrum Fuel Cycle Options

    International Nuclear Information System (INIS)

    Yang, Won Sik; Lin, C. S.; Hader, J. S.; Park, T. K.; Deng, P.; Yang, G.; Jung, Y. S.; Kim, T. K.; Stauff, N. E.

    2016-01-01

    This report presents the performance characteristics of two ''two-stage'' fast spectrum fuel cycle options proposed to enhance uranium resource utilization and to reduce nuclear waste generation. One is a two-stage fast spectrum fuel cycle option of continuous recycle of plutonium (Pu) in a fast reactor (FR) and subsequent burning of minor actinides (MAs) in an accelerator-driven system (ADS). The first stage is a sodium-cooled FR fuel cycle starting with low-enriched uranium (LEU) fuel; at the equilibrium cycle, the FR is operated using the recovered Pu and natural uranium without supporting LEU. Pu and uranium (U) are co-extracted from the discharged fuel and recycled in the first stage, and the recovered MAs are sent to the second stage. The second stage is a sodium-cooled ADS in which MAs are burned in an inert matrix fuel form. The discharged fuel of ADS is reprocessed, and all the recovered heavy metals (HMs) are recycled into the ADS. The other is a two-stage FR/ADS fuel cycle option with MA targets loaded in the FR. The recovered MAs are not directly sent to ADS, but partially incinerated in the FR in order to reduce the amount of MAs to be sent to the ADS. This is a heterogeneous recycling option of transuranic (TRU) elements

  6. Two-stage commercial evaluation of engineering systems production projects for high-rise buildings

    Science.gov (United States)

    Bril, Aleksander; Kalinina, Olga; Levina, Anastasia

    2018-03-01

    The paper is devoted to the current and debatable problem of methodology of choosing the effective innovative enterprises for venture financing. A two-stage system of commercial innovation evaluation based on the UNIDO methodology is proposed. Engineering systems account for 25 to 40% of the cost of high-rise residential buildings. This proportion increases with the use of new construction technologies. Analysis of the construction market in Russia showed that the production of internal engineering systems elements based on innovative technologies has a growth trend. The production of simple elements is organized in small enterprises on the basis of new technologies. The most attractive for development is the use of venture financing of small innovative business. To improve the efficiency of these operations, the paper proposes a methodology for a two-stage evaluation of small business development projects. A two-stage system of commercial evaluation of innovative projects allows creating an information base for informed and coordinated decision-making on venture financing of enterprises that produce engineering systems elements for the construction business.

  7. Two-stage commercial evaluation of engineering systems production projects for high-rise buildings

    Directory of Open Access Journals (Sweden)

    Bril Aleksander

    2018-01-01

    Full Text Available The paper is devoted to the current and debatable problem of methodology of choosing the effective innovative enterprises for venture financing. A two-stage system of commercial innovation evaluation based on the UNIDO methodology is proposed. Engineering systems account for 25 to 40% of the cost of high-rise residential buildings. This proportion increases with the use of new construction technologies. Analysis of the construction market in Russia showed that the production of internal engineering systems elements based on innovative technologies has a growth trend. The production of simple elements is organized in small enterprises on the basis of new technologies. The most attractive for development is the use of venture financing of small innovative business. To improve the efficiency of these operations, the paper proposes a methodology for a two-stage evaluation of small business development projects. A two-stage system of commercial evaluation of innovative projects allows creating an information base for informed and coordinated decision-making on venture financing of enterprises that produce engineering systems elements for the construction business.

  8. Two-Stage Liver Transplantation with Temporary Porto-Middle Hepatic Vein Shunt

    Directory of Open Access Journals (Sweden)

    Giovanni Varotti

    2010-01-01

    Full Text Available Two-stage liver transplantation (LT has been reported for cases of fulminant liver failure that can lead to toxic hepatic syndrome, or massive hemorrhages resulting in uncontrollable bleeding. Technically, the first stage of the procedure consists of a total hepatectomy with preservation of the recipient's inferior vena cava (IVC, followed by the creation of a temporary end-to-side porto-caval shunt (TPCS. The second stage consists of removing the TPCS and implanting a liver graft when one becomes available. We report a case of a two-stage total hepatectomy and LT in which a temporary end-to-end anastomosis between the portal vein and the middle hepatic vein (TPMHV was performed as an alternative to the classic end-to-end TPCS. The creation of a TPMHV proved technically feasible and showed some advantages compared to the standard TPCS. In cases in which a two-stage LT with side-to-side caval reconstruction is utilized, TPMHV can be considered as a safe and effective alternative to standard TPCS.

  9. Habilidades cognitivas em indivíduos muito idosos: um estudo longitudinal Cognitive abilities in older seniors: a longitudinal study

    Directory of Open Access Journals (Sweden)

    Irani I. de Lima Argimon

    2005-02-01

    Full Text Available Estudos longitudinais com idosos com mais de oitenta anos são escassos na literatura. A pesquisa foi delineada com o objetivo de analisar as modificações no perfil de algumas habilidades cognitivas em indivíduos muito idosos, em dois momentos, com um intervalo de três anos. Pesquisa do tipo quantitativo, com delineamento longitudinal e prospectivo. A amostra, randômica, foi constituída por 66 indivíduos de 80 a 95 anos de idade na etapa I e, três anos após, na etapa II, por 46 idosos. Os instrumentos usados foram: Escala de Depressão Geriátrica, Questionário de Percepção Subjetiva de Queixas de Memória, Mini-Exame do Estado Mental, Span de Números, Teste de Lembranças Livres e com Pistas de Buschke, Teste de Fluência Verbal - Categoria Animal. Houve uma pequena tendência de decréscimo no desempenho cognitivo em um período de três anos. Maior número de atividades de lazer e mais anos de escolaridade foram fatores preditivos de menor variação no desempenho cognitivo. Apesar da idade avançada, os idosos apresentaram um desempenho de habilidades cognitivas cujo declínio foi de intensidade leve, não sendo suficiente para acarretar mudanças significativas no seu padrão cognitivo.Longitudinal studies of older seniors (over 80 years are rare in the literature. This research was designed to study cognitive abilities in the oldest old at two different moments with a three-year interval. The research was quantitative, with a longitudinal and prospective design. The sample consisted of 66 individuals from 80 to 95 years of age, randomly selected for phase I, with 46 of these individuals tested again three years later, in phase II. The instruments used were: Geriatric Depression Scale, Subjective Perception of Memory Problems, Mini-Mental State Examination, Digit Span, Buschke Test of Free and Cued Recall, and the Verbal Fluency Test - Animal Category. The results indicated that there was a small downward trend in the older

  10. Use of missing data methods in longitudinal studies: the persistence of bad practices in developmental psychology.

    Science.gov (United States)

    Jelicić, Helena; Phelps, Erin; Lerner, Richard M

    2009-07-01

    Developmental science rests on describing, explaining, and optimizing intraindividual changes and, hence, empirically requires longitudinal research. Problems of missing data arise in most longitudinal studies, thus creating challenges for interpreting the substance and structure of intraindividual change. Using a sample of reports of longitudinal studies obtained from three flagship developmental journals-Child Development, Developmental Psychology, and Journal of Research on Adolescence-we examined the number of longitudinal studies reporting missing data and the missing data techniques used. Of the 100 longitudinal studies sampled, 57 either reported having missing data or had discrepancies in sample sizes reported for different analyses. The majority of these studies (82%) used missing data techniques that are statistically problematic (either listwise deletion or pairwise deletion) and not among the methods recommended by statisticians (i.e., the direct maximum likelihood method and the multiple imputation method). Implications of these results for developmental theory and application, and the need for understanding the consequences of using statistically inappropriate missing data techniques with actual longitudinal data sets, are discussed.

  11. Simulation-based power calculations for planning a two-stage individual participant data meta-analysis.

    Science.gov (United States)

    Ensor, Joie; Burke, Danielle L; Snell, Kym I E; Hemming, Karla; Riley, Richard D

    2018-05-18

    Researchers and funders should consider the statistical power of planned Individual Participant Data (IPD) meta-analysis projects, as they are often time-consuming and costly. We propose simulation-based power calculations utilising a two-stage framework, and illustrate the approach for a planned IPD meta-analysis of randomised trials with continuous outcomes where the aim is to identify treatment-covariate interactions. The simulation approach has four steps: (i) specify an underlying (data generating) statistical model for trials in the IPD meta-analysis; (ii) use readily available information (e.g. from publications) and prior knowledge (e.g. number of studies promising IPD) to specify model parameter values (e.g. control group mean, intervention effect, treatment-covariate interaction); (iii) simulate an IPD meta-analysis dataset of a particular size from the model, and apply a two-stage IPD meta-analysis to obtain the summary estimate of interest (e.g. interaction effect) and its associated p-value; (iv) repeat the previous step (e.g. thousands of times), then estimate the power to detect a genuine effect by the proportion of summary estimates with a significant p-value. In a planned IPD meta-analysis of lifestyle interventions to reduce weight gain in pregnancy, 14 trials (1183 patients) promised their IPD to examine a treatment-BMI interaction (i.e. whether baseline BMI modifies intervention effect on weight gain). Using our simulation-based approach, a two-stage IPD meta-analysis has meta-analysis was appropriate. Pre-specified adjustment for prognostic factors would increase power further. Incorrect dichotomisation of BMI would reduce power by over 20%, similar to immediately throwing away IPD from ten trials. Simulation-based power calculations could inform the planning and funding of IPD projects, and should be used routinely.

  12. Evaluating the Validity of a Two-stage Sample in a Birth Cohort Established from Administrative Databases.

    Science.gov (United States)

    El-Zein, Mariam; Conus, Florence; Benedetti, Andrea; Parent, Marie-Elise; Rousseau, Marie-Claude

    2016-01-01

    When using administrative databases for epidemiologic research, a subsample of subjects can be interviewed, eliciting information on undocumented confounders. This article presents a thorough investigation of the validity of a two-stage sample encompassing an assessment of nonparticipation and quantification of the extent of bias. Established through record linkage of administrative databases, the Québec Birth Cohort on Immunity and Health (n = 81,496) aims to study the association between Bacillus Calmette-Guérin vaccination and asthma. Among 76,623 subjects classified in four Bacillus Calmette-Guérin-asthma strata, a two-stage sampling strategy with a balanced design was used to randomly select individuals for interviews. We compared stratum-specific sociodemographic characteristics and healthcare utilization of stage 2 participants (n = 1,643) with those of eligible nonparticipants (n = 74,980) and nonrespondents (n = 3,157). We used logistic regression to determine whether participation varied across strata according to these characteristics. The effect of nonparticipation was described by the relative odds ratio (ROR = ORparticipants/ORsource population) for the association between sociodemographic characteristics and asthma. Parental age at childbirth, area of residence, family income, and healthcare utilization were comparable between groups. Participants were slightly more likely to be women and have a mother born in Québec. Participation did not vary across strata by sex, parental birthplace, or material and social deprivation. Estimates were not biased by nonparticipation; most RORs were below one and bias never exceeded 20%. Our analyses evaluate and provide a detailed demonstration of the validity of a two-stage sample for researchers assembling similar research infrastructures.

  13. Using external and internal locking plates in a two-stage protocol for treatment of segmental tibial fractures.

    Science.gov (United States)

    Ma, Ching-Hou; Tu, Yuan-Kun; Yeh, Jih-Hsi; Yang, Shih-Chieh; Wu, Chin-Hsien

    2011-09-01

    The tibial segmental fractures usually follow high-energy trauma and are often associated with many complications. We designed a two-stage protocol for these complex injuries. The aim of this study was to assess the outcome of tibial segmental fractures treated according to this protocol. A prospective series of 25 consecutive segmental tibial fractures were treated using a two-stage procedure. In the first stage, a low-profile locking plate was applied as an external fixator to temporarily immobilize the fractures after anatomic reduction had been achieved followed by soft-tissue reconstruction. The second stage involved definitive internal fixation with a locking plate using a minimally invasive percutaneous plate osteosynthesis technique. The median follow-up was 32 months (range, 20-44 months). All fractures achieved union. The median time for the proximal fracture union was 23 weeks (range, 12-30 weeks) and that for distal fracture union was 27 weeks (range, 12-46 weeks; p = 0.08). Functional results were excellent in 21 patients and good in 4 patients. There were three cases of delayed union of distal fracture. Valgus malunion >5 degrees occurred in two patients, and length discrepancy >1 cm was observed in two patients. Pin tract infection occurred in three patients. Use of the two-stage procedure for treatment of segmental tibial fractures is recommended. Surgeons can achieve good reduction with stable temporary fixation, soft-tissue reconstruction, ease of subsequent definitive fixation, and high union rates. Our patients obtained excellent knee and ankle joint motion, good functional outcomes, and a comfortable clinical course.

  14. SU-E-J-128: Two-Stage Atlas Selection in Multi-Atlas-Based Image Segmentation

    International Nuclear Information System (INIS)

    Zhao, T; Ruan, D

    2015-01-01

    Purpose: In the new era of big data, multi-atlas-based image segmentation is challenged by heterogeneous atlas quality and high computation burden from extensive atlas collection, demanding efficient identification of the most relevant atlases. This study aims to develop a two-stage atlas selection scheme to achieve computational economy with performance guarantee. Methods: We develop a low-cost fusion set selection scheme by introducing a preliminary selection to trim full atlas collection into an augmented subset, alleviating the need for extensive full-fledged registrations. More specifically, fusion set selection is performed in two successive steps: preliminary selection and refinement. An augmented subset is first roughly selected from the whole atlas collection with a simple registration scheme and the corresponding preliminary relevance metric; the augmented subset is further refined into the desired fusion set size, using full-fledged registration and the associated relevance metric. The main novelty of this work is the introduction of an inference model to relate the preliminary and refined relevance metrics, based on which the augmented subset size is rigorously derived to ensure the desired atlases survive the preliminary selection with high probability. Results: The performance and complexity of the proposed two-stage atlas selection method were assessed using a collection of 30 prostate MR images. It achieved comparable segmentation accuracy as the conventional one-stage method with full-fledged registration, but significantly reduced computation time to 1/3 (from 30.82 to 11.04 min per segmentation). Compared with alternative one-stage cost-saving approach, the proposed scheme yielded superior performance with mean and medium DSC of (0.83, 0.85) compared to (0.74, 0.78). Conclusion: This work has developed a model-guided two-stage atlas selection scheme to achieve significant cost reduction while guaranteeing high segmentation accuracy. The benefit

  15. Effect of two-stage sintering process on microstructure and mechanical properties of ODS tungsten heavy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyong H. [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Taejon 305-701 (Korea, Republic of); Cha, Seung I. [International Center for Young Scientists, National Institute for Materials Science 1-1, Namiki, Tsukuba 305-0044 (Japan); Ryu, Ho J. [DUPIC, Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yusong-gu, Taejon 305-353 (Korea, Republic of); Hong, Soon H. [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Taejon 305-701 (Korea, Republic of)], E-mail: shhong@kaist.ac.kr

    2007-06-15

    Oxide dispersion strengthened (ODS) tungsten heavy alloys have been considered as promising candidates for advanced kinetic energy penetrator due to their characteristic fracture mode compared to conventional tungsten heavy alloy. In order to obtain high relative density, the ODS tungsten heavy alloy needs to be sintered at higher temperature for longer time, however, induces growth of tungsten grains. Therefore, it is very difficult to obtain controlled microstructure of ODS tungsten heavy alloy having fine tungsten grains with full densification. In this study, two-stage sintering process, consisted of primary solid-state sintering and followed by secondary liquid phase sintering, was introduced for ODS tungsten heavy alloys. The mechanically alloyed 94W-4.56Ni-1.14Fe-0.3Y{sub 2}O{sub 3} powders are solid-state sintered at 1300-1450 deg. C for 1 h in hydrogen atmosphere, and followed by liquid phase sintering temperature at 1465-1485 deg. C for 0-60 min. The microstructure of ODS tungsten heavy alloys showed high relative density above 97%, with contiguous tungsten grains after primary solid-state sintering. The microstructure of solid-state sintered ODS tungsten heavy alloy was changed into spherical tungsten grains embedded in W-Ni-Fe matrix during secondary liquid phase sintering. The two-stage sintered ODS tungsten heavy alloy from mechanically alloyed powders showed finer microstructure and higher mechanical properties than conventional liquid phase sintered alloy. The mechanical properties of ODS tungsten heavy alloys are dependent on the microstructural parameters such as tungsten grain size, matrix volume fraction and tungsten/tungsten contiguity, which can be controlled through the two-stage sintering process.

  16. Motivational interview with alcoholics: a longitudinal study abstract / A entrevista motivacional com alcoolistas: um estudo longitudinal

    Directory of Open Access Journals (Sweden)

    Margareth da Silva Oliveira

    2008-01-01

    Full Text Available This was a follow up study with alcoholic patients participating in a clinical trial with the use of Motivational Interviewing. 152 subjects were randomly allocated into two groups: the intervention group (IG, which was submitted to Motivational Interviewing, and the control group (CG, submitted to standard treatment. Data were collected with a structured interview and FORM-90. 152 subjects were assessed at the first evaluation (T1, approximately 4 years ago. From 89 subjects who were assessed at follow-up 1 (T2, 59 remained abstinent (37 IG and 22 CG and 30 had relapsed (13 IG and CG. 46 subjects returned for the final evaluation, at follow-up 2 (T3. 29 of them had remained abstinent (20 IG and 10 CG and 17 had relapsed (13 IG and 4CG. Data show that subjects submitted to Motivational Interviewing had better outcomes than the control group in both abstinence maintenance and follow-up attendance.

  17. Longitudinal Andhra Pradesh Eye Disease Study: rationale, study design and research methodology.

    Science.gov (United States)

    Khanna, Rohit C; Murthy, Gudlavalleti Vs; Marmamula, Srinivas; Mettla, Asha Latha; Giridhar, Pyda; Banerjee, Seema; Shekhar, Konegari; Chakrabarti, Subhabrata; Gilbert, Clare; Rao, Gullapalli N

    2016-03-01

    The rationale, objectives, study design and procedures for the longitudinal Andhra Pradesh Eye Disease Study are described. A longitudinal cohort study was carried out. Participants include surviving cohort from the rural component of Andhra Pradesh Eye Disease Study. During 1996-2000, Andhra Pradesh Eye Disease Survey was conducted in three rural (n = 7771) and one urban (n = 2522) areas (now called Andhra Pradesh Eye Disease Study 1). In 2009-2010, a feasibility exercise (Andhra Pradesh Eye Disease Study 2) for a longitudinal study (Andhra Pradesh Eye Disease Study 3) was undertaken in the rural clusters only, as urban clusters no longer existed. In Andhra Pradesh Eye Disease Study 3, a detailed interview will be carried out to collect data on sociodemographic factors, ocular and systemic history, risk factors, visual function, knowledge of eye diseases and barriers to accessing services. All participants will also undergo a comprehensive eye examination including photography of lens, optic disc and retina, Optic Coherence Tomography of the posterior segment, anthropometry, blood pressure and frailty measures. Measures include estimates of the incidence of visual impairment and age-related eye disease (lens opacities, glaucoma and age-related macular degeneration) and the progression of eye disease (lens opacities and myopia) and associated risk factors. Of the 7771 respondents examined in rural areas in Andhra Pradesh Eye Disease Study 1, 5447 (70.1%) participants were traced in Andhra Pradesh Eye Disease Study 2. These participants will be re-examined. Andhra Pradesh Eye Disease Study 3 will provide data on the incidence and progression of visual impairment and major eye diseases and their associated risk factors in India. The study will provide further evidence to aid planning eye care services. © 2015 Royal Australian and New Zealand College of Ophthalmologists.

  18. Development and testing of a two stage granular filter to improve collection efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Rangan, R.S.; Prakash, S.G.; Chakravarti, S.; Rao, S.R.

    1999-07-01

    A circulating bed granular filter (CBGF) with a single filtration stage was tested with a PFB combustor in the Coal Research Facility of BHEL R and D in Hyderabad during the years 1993--95. Filter outlet dust loading varied between 20--50 mg/Nm{sup 3} for an inlet dust loading of 5--8 gms/Nm{sup 3}. The results were reported in Fluidized Bed Combustion-Volume 2, ASME 1995. Though the outlet consists of predominantly fine particulates below 2 microns, it is still beyond present day gas turbine specifications for particulate concentration. In order to enhance the collection efficiency, a two-stage granular filtration concept was evolved, wherein the filter depth is divided between two stages, accommodated in two separate vertically mounted units. The design also incorporates BHEL's scale-up concept of multiple parallel stages. The two-stage concept minimizes reentrainment of captured dust by providing clean granules in the upper stage, from where gases finally exit the filter. The design ensures that dusty gases come in contact with granules having a higher dust concentration at the bottom of the two-stage unit, where most of the cleaning is completed. A second filtration stage of cleaned granules is provided in the top unit (where the granules are returned to the system after dedusting) minimizing reentrainment. Tests were conducted to determine the optimum granule to dust ratio (G/D ratio) which decides the granule circulation rate required for the desired collection efficiency. The data brings out the importance of pre-separation and the limitation on inlet dust loading for any continuous system of granular filtration. Collection efficiencies obtained were much higher (outlet dust being 3--9 mg/Nm{sub 3}) than in the single stage filter tested earlier for similar dust loading at the inlet. The results indicate that two-stage granular filtration has a high potential for HTHT application with fewer risks as compared to other systems under development.

  19. Parenting practices and school dropout: a longitudinal study.

    Science.gov (United States)

    Blondal, Kristjana S; Adalbjarnardottir, Sigrun

    2009-01-01

    Adolescents' perceptions of parenting style and parental involvement in their education were examined longitudinally and related to school dropout among Icelandic youth (N = 427). Results indicated that adolescents who, at age 14, characterized their parents as authoritative (showing acceptance and supervision) were more likely to have completed upper secondary school by age 22 than adolescents from non-authoritative families, controlling for adolescents' gender, socioeconomic status (SES), temperament, and parental involvement. Parenting style seems to more strongly predict school dropout than parental involvement. Further, parenting style may moderate the relationship between parental involvement and dropout, but not in all groups; only in authoritative families does parental involvement decrease the likelihood of school dropout. Furthermore, even after controlling for previous academic achievement, adolescents from authoritative families were less likely to drop out than adolescents from authoritarian and neglectful families. These findings emphasize the importance of encouraging quality parent-child relationships in order to reduce the likelihood of school dropout.

  20. A Longitudinal Study on Human Outdoor Decomposition in Central Texas.

    Science.gov (United States)

    Suckling, Joanna K; Spradley, M Katherine; Godde, Kanya

    2016-01-01

    The development of a methodology that estimates the postmortem interval (PMI) from stages of decomposition is a goal for which forensic practitioners strive. A proposed equation (Megyesi et al. 2005) that utilizes total body score (TBS) and accumulated degree days (ADD) was tested using longitudinal data collected from human remains donated to the Forensic Anthropology Research Facility (FARF) at Texas State University-San Marcos. Exact binomial tests examined the rate of the equation to successfully predict ADD. Statistically significant differences were found between ADD estimated by the equation and the observed value for decomposition stage. Differences remained significant after carnivore scavenged donations were removed from analysis. Low success rates for the equation to predict ADD from TBS and the wide standard errors demonstrate the need to re-evaluate the use of this equation and methodology for PMI estimation in different environments; rather, multivariate methods and equations should be derived that are environmentally specific. © 2015 American Academy of Forensic Sciences.

  1. The construction and use of bacterial DNA microarrays based on an optimized two-stage PCR strategy

    Directory of Open Access Journals (Sweden)

    Pesta David

    2003-06-01

    Full Text Available Abstract Background DNA microarrays are a powerful tool with important applications such as global gene expression profiling. Construction of bacterial DNA microarrays from genomic sequence data using a two-stage PCR amplification approach for the production of arrayed DNA is attractive because it allows, in principal, the continued re-amplification of DNA fragments and facilitates further utilization of the DNA fragments for additional uses (e.g. over-expression of protein. We describe the successful construction and use of DNA microarrays by the two-stage amplification approach and discuss the technical challenges that were met and resolved during the project. Results Chimeric primers that contained both gene-specific and shared, universal sequence allowed the two-stage amplification of the 3,168 genes identified on the genome of Synechocystis sp. PCC6803, an important prokaryotic model organism for the study of oxygenic photosynthesis. The gene-specific component of the primer was of variable length to maintain uniform annealing temperatures during the 1st round of PCR synthesis, and situated to preserve full-length ORFs. Genes were truncated at 2 kb for efficient amplification, so that about 92% of the PCR fragments were full-length genes. The two-stage amplification had the additional advantage of normalizing the yield of PCR products and this improved the uniformity of DNA features robotically deposited onto the microarray surface. We also describe the techniques utilized to optimize hybridization conditions and signal-to-noise ratio of the transcription profile. The inter-lab transportability was demonstrated by the virtual error-free amplification of the entire genome complement of 3,168 genes using the universal primers in partner labs. The printed slides have been successfully used to identify differentially expressed genes in response to a number of environmental conditions, including salt stress. Conclusions The technique detailed

  2. A entrevista motivacional com alcoolistas: um estudo longitudinal Motivational interview with alcoholics: a longitudinal study abstract

    Directory of Open Access Journals (Sweden)

    Margareth da Silva Oliveira

    2008-01-01

    Full Text Available Este foi um estudo de seguimento com pacientes alcoolistas que participaram de um ensaio clínico em que foi empregada Entrevista Motivacional. A amostra constituiu-se de 152 sujeitos alocados randomicamente em dois grupos: grupo de intervenção submetido à Entrevista Motivacional (GI, e um grupo controle submetido a tratamento padrão (GC. Os instrumentos utilizados foram: entrevista estruturada e o FORM-90. Na avaliação inicial (T1, realizada entre os anos de 1999 e 2001, foram avaliados 152 sujeitos; para o follow-up 1, na segunda avaliação (T2, foram avaliados 89 sujeitos, dos quais 59 permaneciam abstinentes (37GI e 22GC e 30 haviam recaído (13GE e 17GC; já para o follow-up 2, na avaliação final (T3 - entre os anos de 2003 e 2005, regressaram 46 sujeitos, dos quais 29 mantinham-se abstinentes (20GI e 10GC e 17 recaíram (13GI e 4GC. Esses dados demonstram que os sujeitos submetidos à Entrevista Motivacional tiveram mais êxito na manutenção da abstinência e compareceram em maior número aos follow-up, demonstrando melhores resultados comparados com o grupo controle.This was a follow up study with alcoholic patients participating in a clinical trial with the use of Motivational Interviewing. 152 subjects were randomly allocated into two groups: the intervention group (IG, which was submitted to Motivational Interviewing, and the control group (CG, submitted to standard treatment. Data were collected with a structured interview and FORM-90. 152 subjects were assessed at the first evaluation (T1, approximately 4 years ago. From 89 subjects who were assessed at follow-up 1 (T2, 59 remained abstinent (37 IG and 22 CG and 30 had relapsed (13 IG and CG. 46 subjects returned for the final evaluation, at follow-up 2 (T3. 29 of them had remained abstinent (20 IG and 10 CG and 17 had relapsed (13 IG and 4CG. Data show that subjects submitted to Motivational Interviewing had better outcomes than the control group in both abstinence

  3. A simulation-based interval two-stage stochastic model for agricultural nonpoint source pollution control through land retirement

    International Nuclear Information System (INIS)

    Luo, B.; Li, J.B.; Huang, G.H.; Li, H.L.

    2006-01-01

    This study presents a simulation-based interval two-stage stochastic programming (SITSP) model for agricultural nonpoint source (NPS) pollution control through land retirement under uncertain conditions. The modeling framework was established by the development of an interval two-stage stochastic program, with its random parameters being provided by the statistical analysis of the simulation outcomes of a distributed water quality approach. The developed model can deal with the tradeoff between agricultural revenue and 'off-site' water quality concern under random effluent discharge for a land retirement scheme through minimizing the expected value of long-term total economic and environmental cost. In addition, the uncertainties presented as interval numbers in the agriculture-water system can be effectively quantified with the interval programming. By subdividing the whole agricultural watershed into different zones, the most pollution-related sensitive cropland can be identified and an optimal land retirement scheme can be obtained through the modeling approach. The developed method was applied to the Swift Current Creek watershed in Canada for soil erosion control through land retirement. The Hydrological Simulation Program-FORTRAN (HSPF) was used to simulate the sediment information for this case study. Obtained results indicate that the total economic and environmental cost of the entire agriculture-water system can be limited within an interval value for the optimal land retirement schemes. Meanwhile, a best and worst land retirement scheme was obtained for the study watershed under various uncertainties

  4. Chronic infections in hip arthroplasties: comparing risk of reinfection following one-stage and two-stage revision: a systematic review and meta-analysis

    Directory of Open Access Journals (Sweden)

    Lange J

    2012-03-01

    Full Text Available Jeppe Lange1,2, Anders Troelsen3, Reimar W Thomsen4, Kjeld Søballe1,51Lundbeck Foundation Centre for Fast-Track Hip and Knee Surgery, Aarhus C, 2Center for Planned Surgery, Silkeborg Regional Hospital, Silkeborg, 3Department of Orthopaedics, Hvidovre Hospital, Hvidovre, 4Department of Clinical Epidemiology, Aarhus University Hospital, Aalborg, 5Department of Orthopaedics, Aarhus University Hospital, Aarhus C, DenmarkBackground: Two-stage revision is regarded by many as the best treatment of chronic infection in hip arthroplasties. Some international reports, however, have advocated one-stage revision. No systematic review or meta-analysis has ever compared the risk of reinfection following one-stage and two-stage revisions for chronic infection in hip arthroplasties.Methods: The review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis. Relevant studies were identified using PubMed and Embase. We assessed studies that included patients with a chronic infection of a hip arthroplasty treated with either one-stage or two-stage revision and with available data on occurrence of reinfections. We performed a meta-analysis estimating absolute risk of reinfection using a random-effects model.Results: We identified 36 studies eligible for inclusion. None were randomized controlled trials or comparative studies. The patients in these studies had received either one-stage revision (n = 375 or two-stage revision (n = 929. Reinfection occurred with an estimated absolute risk of 13.1% (95% confidence interval: 10.0%–17.1% in the one-stage cohort and 10.4% (95% confidence interval: 8.5%–12.7% in the two-stage cohort. The methodological quality of most included studies was considered low, with insufficient data to evaluate confounding factors.Conclusions: Our results may indicate three additional reinfections per 100 reimplanted patients when performing a one-stage versus two-stage revision. However, the

  5. Biotransformation of Domestic Wastewater Treatment Plant Sludge by Two-Stage Integrated Processes -Lsb & Ssb

    Directory of Open Access Journals (Sweden)

    Md. Zahangir Alam, A. H. Molla and A. Fakhru’l-Razi

    2012-10-01

    Full Text Available The study of biotransformation of domestic wastewater treatment plant (DWTP sludge was conducted in laboratory-scale by two-stage integrated process i.e. liquid state bioconversion (LSB and solid state bioconversion (SSB processes. The liquid wastewater sludge [4% w/w of total suspended solids (TSS] was treated by mixed filamentous fungi Penicillium corylophilum and Aspergillus niger, isolated, screened and mixed cultured in terms of their higher biodegradation potential to wastewater sludge. The biosolids was increased to about 10% w/w. Conversely, the soluble [i.e. Total dissolve solid (TDS] and insoluble substances (TSS in treated supernatant were decreased effectively in the LSB process. In the developed LSB process, 93.8 g kg-1of biosolids were enriched with fungal biomass protein and nutrients (NPK, and 98.8% of TSS, 98.2% of TDS, 97.3% of turbidity, 80.2% of soluble protein, 98.8% of reducing sugar and 92.7% of chemical oxygen demand (COD in treated sludge supernatant were removed after 8 days of treatment. Specific resistance to filtration (1.39x1012 m/kg was decreased tremendously by the microbial treatment of DWTP sludge after 6 days of fermentation. The treated biosolids in DWTP sludge was considered as pretreated resource materials for composting and converted into compost by SSB process. The SSB process was evaluated for composting by monitoring the microbial growth and its subsequent roles in biodegradation in composting bin (CB. The process was conducted using two mixed fungal cultures, Trichoderma harzianum with Phanerochaete chrysosporium 2094 and (T/P and T. harzianum and Mucor hiemalis (T/M; and two bulking materials, sawdust (SD and rice straw (RS. The most encouraging results of microbial growth and subsequent solid state bioconversion were exhibited in the RS than the SD. Significant decrease of the C/N ratio and germination index (GI were attained as well as the higher value of glucosamine was exhibited in compost; which

  6. A longitudinal study of age-related changes in intraocular pressure: the Kangbuk Samsung Health Study.

    Science.gov (United States)

    Zhao, Di; Kim, Myung Hun; Pastor-Barriuso, Roberto; Chang, Yoosoo; Ryu, Seungho; Zhang, Yiyi; Rampal, Sanjay; Shin, Hocheol; Kim, Joon Mo; Friedman, David S; Guallar, Eliseo; Cho, Juhee

    2014-09-02

    To examine the longitudinal association between age and intraocular pressure (IOP) in a large sample of Korean men and women. We conducted a prospective cohort study of 274,064 young and middle-aged Korean adults with normal fundoscopic findings, following them from January 1, 2002, to February 28, 2010. Health exams were scheduled annually or biennially. At each visit, IOP was measured in both eyes using automated noncontact tonometers. The longitudinal change in IOP with age was evaluated using three-level mixed models for longitudinal paired-eye data, accounting for correlations between paired eyes and repeated measurements over time. In fully adjusted models, the average longitudinal change in IOP per 1-year increase in age was -0.065 mm Hg (95% confidence interval [CI] -0.068 to -0.063), with marked sex differences (P < 0.001). In men, the average annual IOP change was -0.093 mm Hg (95% CI -0.096 to -0.091) throughout follow-up. In women, the average annual IOP change was -0.006 mm Hg (95% CI -0.010 to -0.003), with a relatively flat association in the age range of 30 to 59 years and more marked annual decreases at younger and older ages. Intraocular pressure was inversely associated with age in a large cohort of Korean adults attending health-screening visits. For men, this inverse association was observed throughout the entire age range, while for women it was evident only in younger (<30 years of age) and older (≥60 years of age) women, with no association in women aged 30 to 59. Further research is needed to better understand the underlying mechanisms and to reconsider cutoffs for defining high IOP by age and sex groups in Asian populations. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  7. Maximum likelihood estimation of signal detection model parameters for the assessment of two-stage diagnostic strategies.

    Science.gov (United States)

    Lirio, R B; Dondériz, I C; Pérez Abalo, M C

    1992-08-01

    The methodology of Receiver Operating Characteristic curves based on the signal detection model is extended to evaluate the accuracy of two-stage diagnostic strategies. A computer program is developed for the maximum likelihood estimation of parameters that characterize the sensitivity and specificity of two-stage classifiers according to this extended methodology. Its use is briefly illustrated with data collected in a two-stage screening for auditory defects.

  8. What is learned from longitudinal studies of advertising and youth drinking and smoking? A critical assessment.

    Science.gov (United States)

    Nelson, Jon P

    2010-03-01

    This paper assesses the methodology employed in longitudinal studies of advertising and youth drinking and smoking behaviors. These studies often are given a causal interpretation in the psychology and public health literatures. Four issues are examined from the perspective of econometrics. First, specification and validation of empirical models. Second, empirical issues associated with measures of advertising receptivity and exposure. Third, potential endogeneity of receptivity and exposure variables. Fourth, sample selection bias in baseline and follow-up surveys. Longitudinal studies reviewed include 20 studies of youth drinking and 26 studies of youth smoking. Substantial shortcomings are found in the studies, which preclude a causal interpretation.

  9. What is Learned from Longitudinal Studies of Advertising and Youth Drinking and Smoking? A Critical Assessment

    Directory of Open Access Journals (Sweden)

    Jon P. Nelson

    2010-03-01

    Full Text Available This paper assesses the methodology employed in longitudinal studies of advertising and youth drinking and smoking behaviors. These studies often are given a causal interpretation in the psychology and public health literatures. Four issues are examined from the perspective of econometrics. First, specification and validation of empirical models. Second, empirical issues associated with measures of advertising receptivity and exposure. Third, potential endogeneity of receptivity and exposure variables. Fourth, sample selection bias in baseline and follow-up surveys. Longitudinal studies reviewed include 20 studies of youth drinking and 26 studies of youth smoking. Substantial shortcomings are found in the studies, which preclude a causal interpretation.

  10. A Comparison of Two-Stage Approaches for Fitting Nonlinear Ordinary Differential Equation Models with Mixed Effects.

    Science.gov (United States)

    Chow, Sy-Miin; Bendezú, Jason J; Cole, Pamela M; Ram, Nilam

    2016-01-01

    Several approaches exist for estimating the derivatives of observed data for model exploration purposes, including functional data analysis (FDA; Ramsay & Silverman, 2005 ), generalized local linear approximation (GLLA; Boker, Deboeck, Edler, & Peel, 2010 ), and generalized orthogonal local derivative approximation (GOLD; Deboeck, 2010 ). These derivative estimation procedures can be used in a two-stage process to fit mixed effects ordinary differential equation (ODE) models. While the performance and utility of these routines for estimating linear ODEs have been established, they have not yet been evaluated in the context of nonlinear ODEs with mixed effects. We compared properties of the GLLA and GOLD to an FDA-based two-stage approach denoted herein as functional ordinary differential equation with mixed effects (FODEmixed) in a Monte Carlo (MC) study using a nonlinear coupled oscillators model with mixed effects. Simulation results showed that overall, the FODEmixed outperformed both the GLLA and GOLD across all the embedding dimensions considered, but a novel use of a fourth-order GLLA approach combined with very high embedding dimensions yielded estimation results that almost paralleled those from the FODEmixed. We discuss the strengths and limitations of each approach and demonstrate how output from each stage of FODEmixed may be used to inform empirical modeling of young children's self-regulation.

  11. Research on the Power Recovery of Diesel Engines with Regulated Two-Stage Turbocharging System at Different Altitudes

    Directory of Open Access Journals (Sweden)

    Hualei Li

    2014-01-01

    Full Text Available Recovering the boost pressure is very important in improving the dynamic performance of diesel engines at high altitudes. A regulated two-stage turbocharging system is an adequate solution for power recovery of diesel engines. In the present study, the change of boost pressure and engine power at different altitudes was investigated, and a regulated two-stage turbocharging system was constructed with an original turbocharger and a matched low pressure turbocharger. The valve control strategies for boost pressure recovery, which formed the basis of the power recovery method, are presented here. The simulation results showed that this system was effective in recovering the boost pressure at different speeds and various altitudes. The turbine bypass valve and compressor bypass valve had different modes to adapt to changes in operating conditions. The boost pressure recovery could not ensure power recovery over the entire operating range of the diesel engine, because of variation in overall turbocharger efficiency. The fuel-injection compensation method along with the valve control strategies for boost pressure recovery was able to reach the power recovery target.

  12. Evaluation of hydrogen and methane production from sugarcane bagasse hemicellulose hydrolysates by two-stage anaerobic digestion process.

    Science.gov (United States)

    Baêta, Bruno Eduardo Lobo; Lima, Diego Roberto Sousa; Filho, José Gabriel Balena; Adarme, Oscar Fernando Herrera; Gurgel, Leandro Vinícius Alves; Aquino, Sérgio Francisco de

    2016-10-01

    This study aimed at optimizing the net energy recovery from hydrogen and methane production through anaerobic digestion of the hemicellulose hydrolysate (HH) obtained by desirable conditions (DC) of autohydrolysis pretreatment (AH) of sugarcane bagasse (SB). Anaerobic digestion was carried out in a two-stage (acidogenic-methanogenic) batch system where the acidogenic phase worked as a hydrolysis and biodetoxification step. This allowed the utilization of more severe AH pretreatment conditions, i.e. T=178.6°C and t=55min (DC3) and T=182.9°C and t=40.71min (DC4). Such severe conditions resulted in higher extraction of hemicelluloses from SB (DC1=68.07%, DC2=48.99%, DC3=77.40% and DC4=73.90%), which consequently improved the net energy balance of the proposed process. The estimated energy from the combustion of both biogases (H2 and CH4) accumulated during the two-stage anaerobic digestion of HH generated by DC4 condition was capable of producing a net energy of 3.15MJ·kgSB(-1)dry weight. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. An adaptive two-stage analog/regression model for probabilistic prediction of small-scale precipitation in France

    Science.gov (United States)

    Chardon, Jérémy; Hingray, Benoit; Favre, Anne-Catherine

    2018-01-01

    Statistical downscaling models (SDMs) are often used to produce local weather scenarios from large-scale atmospheric information. SDMs include transfer functions which are based on a statistical link identified from observations between local weather and a set of large-scale predictors. As physical processes driving surface weather vary in time, the most relevant predictors and the regression link are likely to vary in time too. This is well known for precipitation for instance and the link is thus often estimated after some seasonal stratification of the data. In this study, we present a two-stage analog/regression model where the regression link is estimated from atmospheric analogs of the current prediction day. Atmospheric analogs are identified from fields of geopotential heights at 1000 and 500 hPa. For the regression stage, two generalized linear models are further used to model the probability of precipitation occurrence and the distribution of non-zero precipitation amounts, respectively. The two-stage model is evaluated for the probabilistic prediction of small-scale precipitation over France. It noticeably improves the skill of the prediction for both precipitation occurrence and amount. As the analog days vary from one prediction day to another, the atmospheric predictors selected in the regression stage and the value of the corresponding regression coefficients can vary from one prediction day to another. The model allows thus for a day-to-day adaptive and tailored downscaling. It can also reveal specific predictors for peculiar and non-frequent weather configurations.

  14. High-power free-electron laser amplifier using a scalloped electron beam and a two-stage wiggler

    Directory of Open Access Journals (Sweden)

    D. C. Nguyen

    2006-05-01

    Full Text Available High-power free-electron laser (FEL amplifiers present many practical design and construction problems. One such problem is possible damage to any optical beam control elements beyond the wiggler. The ability to increase the optical beam’s divergence angle after the wiggler, thereby reducing the intensity on the first optical element, is important to minimize such damage. One proposal to accomplish this optical beam spreading is to pinch the electron beam thereby focusing the radiation as well. In this paper, we analyze an approach that relies on the natural betatron motion to pinch the electron beam near the end of the wiggler. We also consider a step-tapered, two-stage wiggler to enhance the efficiency. The combination of a pinched electron beam and step-taper wiggler leads to additional optical guiding of the optical beam. This novel configuration is studied in simulation using the MEDUSA code. For a representative set of beam and wiggler parameters, we discuss (i the effect of the scalloped beam on the interaction in the FEL and on the focusing and propagation of the radiation, and (ii the efficiency enhancement in the two-stage wiggler.

  15. Efficiency and productivity (TFP) of the Turkish electricity distribution companies: An application of two-stage (DEA and Tobit) analysis

    International Nuclear Information System (INIS)

    Çelen, Aydın

    2013-01-01

    In this study, we analyze the efficiency performances of 21 Turkish electricity distribution companies during the period of 2002–2009. For this aim, we employ a two-stage analysis in order to take into account the business environment variables which are beyond the control of distribution companies. We determine the efficiency performances of the electricity distribution companies by help of DEA in the first stage. Then, in the second stage, using these calculated efficiency scores as dependent variable, we utilize Tobit model to determine the business environment variables which may explain the efficiency scores. According to the results, customer density of the region and the private ownership affect the efficiencies positively. Thus, the best strategy to improve efficiency in the market is privatizing the public distribution companies. - Highlights: • We analyze the efficiencies of 21 Turkish electricity distribution companies. • A two-stage analysis is employed to take into account environmental variables. • We firstly calculate efficiencies of companies with DEA, then Tobit model is used to determine the effects of the variables. • Customer density and ownership type affect the efficiencies positively. • Privatization is a good strategy to improve efficiencies

  16. Comparisons of single-stage and two-stage approaches to genomic selection.

    Science.gov (United States)

    Schulz-Streeck, Torben; Ogutu, Joseph O; Piepho, Hans-Peter

    2013-01-01

    Genomic selection (GS) is a method for predicting breeding values of plants or animals using many molecular markers that is commonly implemented in two stages. In plant breeding the first stage usually involves computation of adjusted means for genotypes which are then used to predict genomic breeding values in the second stage. We compared two classical stage-wise approaches, which either ignore or approximate correlations among the means by a diagonal matrix, and a new method, to a single-stage analysis for GS using ridge regression best linear unbiased prediction (RR-BLUP). The new stage-wise method rotates (orthogonalizes) the adjusted means from the first stage before submitting them to the second stage. This makes the errors approximately independently and identically normally distributed, which is a prerequisite for many procedures that are potentially useful for GS such as machine learning methods (e.g. boosting) and regularized regression methods (e.g. lasso). This is illustrated in this paper using componentwise boosting. The componentwise boosting method minimizes squared error loss using least squares and iteratively and automatically selects markers that are most predictive of genomic breeding values. Results are compared with those of RR-BLUP using fivefold cross-validation. The new stage-wise approach with rotated means was slightly more similar to the single-stage analysis than the classical two-stage approaches based on non-rotated means for two unbalanced datasets. This suggests that rotation is a worthwhile pre-processing step in GS for the two-stage approaches for unbalanced datasets. Moreover, the predictive accuracy of stage-wise RR-BLUP was higher (5.0-6.1%) than that of componentwise boosting.

  17. Clinical evaluation of two-stage mandibular wisdom tooth extraction method to avoid mental nerve paresthesia

    International Nuclear Information System (INIS)

    Nozoe, Etsuro; Nakamura, Yasunori; Okawachi, Takako; Ishihata, Kiyohide; Shinnakasu, Mana; Nakamura, Norifumi

    2011-01-01

    Clinical courses following two-stage mandibular wisdom tooth extraction (TMWTE) carried out for preventing postoperative mental nerve paresthesia (MNP) were analyzed. When panoramic X-ray showed overlapping of wisdom tooth root on the superior 1/2 or more of the mandibular canal, interruption of the white line of the superior wall of the canal, or diversion of the canal, CT examination was facilitated. In cases where contact between the tooth root and canal was demonstrated in CT examination, TMWTE was then selected after gaining the patient's consent. TMWTE consisted of removing more than a half of the tooth crown and tooth root extraction at the second step after 2-3 months. The clinical features of wisdom teeth extracted and postoperative courses including tooth movement and occurrence of MNP during two-stage MWTE were evaluated. TMWTE was carried out for 40 teeth among 811 wisdom teeth (4.9%) that were extracted from 2007 to 2009. Among them, complete procedures were accomplished in 39 teeth, and crown removal was performed insufficiently at the first-stage operation in one tooth. Tooth movement was detected in 37 of 40 cases (92.5%). No postoperative MNP was observed in cases in which complete two-stage MWTE was carried out, but one case with insufficient crown removal was complicated by postoperative MNP. Seven mild complications (dehiscence, cold sensitivity, etc.) were noted after the first-stage operation. Therefore, we conclude that TMWTE for high-risk cases assessed by X-ray findings is useful to avoid MNP after MWTE. (author)

  18. Forbidden fruit? A longitudinal study of Christianity, sex, and marriage.

    Science.gov (United States)

    Pedersen, Willy

    2014-01-01

    Does religion still play a role in explorations of romance and sexuality among adolescents and young adults in a secular society such as Norway? Does it influence the type of living arrangements chosen? A population-based sample (n = 2,454) was followed longitudinally from their midteens to their late 20s using survey and register data. Christian involvement in teenage years was associated with subsequent less "precoital" exploration, less masturbation, delayed sexual intercourse, and a smaller number of sex partners. However, there were no associations with prevalence of same-sex experiences. Christians also postponed initiating romantic relationships and chose marriage over cohabitation. Associations were reduced after controlling for confounding factors but remained significant. Some associations (for example, the form of residential union chosen) were present only in the most "active" Christians. In other areas, such as "precoital explorations" and the age at which intercourse is initiated, Christian norms seem to play a role in much broader segments of the population. The findings indicate that Christianity may continue to influence young Norwegians' experiences of sexuality and cohabitation more than has been expected.

  19. Cumulative risk, cumulative outcome: a 20-year longitudinal study.

    Directory of Open Access Journals (Sweden)

    Leslie Atkinson

    Full Text Available Cumulative risk (CR models provide some of the most robust findings in the developmental literature, predicting numerous and varied outcomes. Typically, however, these outcomes are predicted one at a time, across different samples, using concurrent designs, longitudinal designs of short duration, or retrospective designs. We predicted that a single CR index, applied within a single sample, would prospectively predict diverse outcomes, i.e., depression, intelligence, school dropout, arrest, smoking, and physical disease from childhood to adulthood. Further, we predicted that number of risk factors would predict number of adverse outcomes (cumulative outcome; CO. We also predicted that early CR (assessed at age 5/6 explains variance in CO above and beyond that explained by subsequent risk (assessed at ages 12/13 and 19/20. The sample consisted of 284 individuals, 48% of whom were diagnosed with a speech/language disorder. Cumulative risk, assessed at 5/6-, 12/13-, and 19/20-years-old, predicted aforementioned outcomes at age 25/26 in every instance. Furthermore, number of risk factors was positively associated with number of negative outcomes. Finally, early risk accounted for variance beyond that explained by later risk in the prediction of CO. We discuss these findings in terms of five criteria posed by these data, positing a "mediated net of adversity" model, suggesting that CR may increase some central integrative factor, simultaneously augmenting risk across cognitive, quality of life, psychiatric and physical health outcomes.

  20. Teaching basic life support with an automated external defibrillator using the two-stage or the four-stage teaching technique.

    Science.gov (United States)

    Bjørnshave, Katrine; Krogh, Lise Q; Hansen, Svend B; Nebsbjerg, Mette A; Thim, Troels; Løfgren, Bo

    2018-02-01

    Laypersons often hesitate to perform basic life support (BLS) and use an automated external defibrillator (AED) because of self-perceived lack of knowledge and skills. Training may reduce the barrier to intervene. Reduced training time and costs may allow training of more laypersons. The aim of this study was to compare BLS/AED skills' acquisition and self-evaluated BLS/AED skills after instructor-led training with a two-stage versus a four-stage teaching technique. Laypersons were randomized to either two-stage or four-stage teaching technique courses. Immediately after training, the participants were tested in a simulated cardiac arrest scenario to assess their BLS/AED skills. Skills were assessed using the European Resuscitation Council BLS/AED assessment form. The primary endpoint was passing the test (17 of 17 skills adequately performed). A prespecified noninferiority margin of 20% was used. The two-stage teaching technique (n=72, pass rate 57%) was noninferior to the four-stage technique (n=70, pass rate 59%), with a difference in pass rates of -2%; 95% confidence interval: -18 to 15%. Neither were there significant differences between the two-stage and four-stage groups in the chest compression rate (114±12 vs. 115±14/min), chest compression depth (47±9 vs. 48±9 mm) and number of sufficient rescue breaths between compression cycles (1.7±0.5 vs. 1.6±0.7). In both groups, all participants believed that their training had improved their skills. Teaching laypersons BLS/AED using the two-stage teaching technique was noninferior to the four-stage teaching technique, although the pass rate was -2% (95% confidence interval: -18 to 15%) lower with the two-stage teaching technique.