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Sample records for modeling unstable eor

  1. Revisiting EOR Projects in Indonesia through Integrated Study: EOR Screening, Predictive Model, and Optimisation

    Hartono, A. D.; Hakiki, Farizal; Syihab, Z.; Ambia, F.; Yasutra, A.; Sutopo, S.; Efendi, M.; Sitompul, V.; Primasari, I.; Apriandi, R.

    2017-01-01

    EOR preliminary analysis is pivotal to be performed at early stage of assessment in order to elucidate EOR feasibility. This study proposes an in-depth analysis toolkit for EOR preliminary evaluation. The toolkit incorporates EOR screening, predictive, economic, risk analysis and optimisation modules. The screening module introduces algorithms which assimilates statistical and engineering notions into consideration. The United States Department of Energy (U.S. DOE) predictive models were implemented in the predictive module. The economic module is available to assess project attractiveness, while Monte Carlo Simulation is applied to quantify risk and uncertainty of the evaluated project. Optimization scenario of EOR practice can be evaluated using the optimisation module, in which stochastic methods of Genetic Algorithms (GA), Particle Swarm Optimization (PSO) and Evolutionary Strategy (ES) were applied in the algorithms. The modules were combined into an integrated package of EOR preliminary assessment. Finally, we utilised the toolkit to evaluate several Indonesian oil fields for EOR evaluation (past projects) and feasibility (future projects). The attempt was able to update the previous consideration regarding EOR attractiveness and open new opportunity for EOR implementation in Indonesia.

  2. Revisiting EOR Projects in Indonesia through Integrated Study: EOR Screening, Predictive Model, and Optimisation

    Hartono, A. D.

    2017-10-17

    EOR preliminary analysis is pivotal to be performed at early stage of assessment in order to elucidate EOR feasibility. This study proposes an in-depth analysis toolkit for EOR preliminary evaluation. The toolkit incorporates EOR screening, predictive, economic, risk analysis and optimisation modules. The screening module introduces algorithms which assimilates statistical and engineering notions into consideration. The United States Department of Energy (U.S. DOE) predictive models were implemented in the predictive module. The economic module is available to assess project attractiveness, while Monte Carlo Simulation is applied to quantify risk and uncertainty of the evaluated project. Optimization scenario of EOR practice can be evaluated using the optimisation module, in which stochastic methods of Genetic Algorithms (GA), Particle Swarm Optimization (PSO) and Evolutionary Strategy (ES) were applied in the algorithms. The modules were combined into an integrated package of EOR preliminary assessment. Finally, we utilised the toolkit to evaluate several Indonesian oil fields for EOR evaluation (past projects) and feasibility (future projects). The attempt was able to update the previous consideration regarding EOR attractiveness and open new opportunity for EOR implementation in Indonesia.

  3. Evaluation of EOR Processes Using Network Models

    Winter, Anatol; Larsen, Jens Kjell; Krogsbøll, Anette

    1998-01-01

    The report consists of the following parts: 1) Studies of wetting properties of model fluids and fluid mixtures aimed at an optimal selection of candidates for micromodel experiments. 2) Experimental studies of multiphase transport properties using physical models of porous networks (micromodels......) including estimation of their "petrophysical" properties (e.g. absolute permeability). 3) Mathematical modelling and computer studies of multiphase transport through pore space using mathematical network models. 4) Investigation of link between pore-scale and macroscopic recovery mechanisms....

  4. A Clustered Extragalactic Foreground Model for the EoR

    Murray, S. G.; Trott, C. M.; Jordan, C. H.

    2018-05-01

    We review an improved statistical model of extra-galactic point-source foregrounds first introduced in Murray et al. (2017), in the context of the Epoch of Reionization. This model extends the instrumentally-convolved foreground covariance used in inverse-covariance foreground mitigation schemes, by considering the cosmological clustering of the sources. In this short work, we show that over scales of k ~ (0.6, 40.)hMpc-1, ignoring source clustering is a valid approximation. This is in contrast to Murray et al. (2017), who found a possibility of false detection if the clustering was ignored. The dominant cause for this change is the introduction of a Galactic synchrotron component which shadows the clustering of sources.

  5. Impact of Three-Phase Relative Permeability and Hysteresis Models on Forecasts of Storage Associated With CO2-EOR

    Jia, Wei; McPherson, Brian; Pan, Feng; Dai, Zhenxue; Moodie, Nathan; Xiao, Ting

    2018-02-01

    Geological CO2 sequestration in conjunction with enhanced oil recovery (CO2-EOR) includes complex multiphase flow processes compared to CO2 storage in deep saline aquifers. Two of the most important factors affecting multiphase flow in CO2-EOR are three-phase relative permeability and associated hysteresis, both of which are difficult to measure and are usually represented by numerical interpolation models. The purpose of this study is to improve understanding of (1) the relative impacts of different three-phase relative permeability models and hysteresis models on CO2 trapping mechanisms, and (2) uncertainty associated with these two factors. Four different three-phase relative permeability models and three hysteresis models were applied to simulations of an active CO2-EOR site, the SACROC unit located in western Texas. To eliminate possible bias of deterministic parameters, we utilized a sequential Gaussian simulation technique to generate 50 realizations to describe heterogeneity of porosity and permeability, based on data obtained from well logs and seismic survey. Simulation results of forecasted CO2 storage suggested that (1) the choice of three-phase relative permeability model and hysteresis model led to noticeable impacts on forecasted CO2 sequestration capacity; (2) impacts of three-phase relative permeability models and hysteresis models on CO2 trapping are small during the CO2-EOR injection period, and increase during the post-EOR CO2 injection period; (3) the specific choice of hysteresis model is more important relative to the choice of three-phase relative permeability model; and (4) using the recommended three-phase WAG (Water-Alternating-Gas) hysteresis model may increase the impact of three-phase relative permeability models and uncertainty due to heterogeneity.

  6. A 2d model for the effect of gas diffusion on mobility of foam for EOR

    Nonnekes, L.E.; Cox, S.J.; Rossen, W.R.

    2012-01-01

    Transport of gas across liquid films between bubbles is cited as one reason why CO2 foams for enhanced oil recovery (EOR) are usually weaker than N2 foams and why steam foams are weaker than foams of steam mixed with N2. We examine here the effect of inter-bubble gas diffusion on flowing bubbles in

  7. Monitoring of magnetic nano-particles in EOR by using the CSEM modeling and inversion.

    Heo, J. Y.; KIM, S.; Jeong, G.; Hwang, J.; Min, D. J.

    2016-12-01

    EOR, which injects water, CO2, or other chemical components into reservoirs to increase the production rate of oil and gas, has widely been used. To promote efficiency of EOR, it is important to monitor distribution of injected materials in reservoirs. Using nano-particles in EOR has advantages that the size of particles is smaller than the pore and particles can be characterized by various physical properties. Specifically, if we use magnetic nano-particles, we can effectively monitor nano-particles by using the electromagnetic survey. CSEM, which can control the frequency range of source, is good to monitor magnetic nano-particles under various reservoir circumstances. In this study, we first perform numerical simulation of 3D CSEM for reservoir under production. In general, two wells are used for EOR: one is for injection, and the other is for extraction. We assume that sources are applied inside the injection well, and receivers are deployed inside the extraction well. To simulate the CSEM survey, we decompose the total fields into primary and secondary fields in Maxwell's equations. For the primary fields, we calculate the analytic solutions of the layered earth. With the calculated primary fields, we compute the secondary fields due to anomalies using the edge-based finite-element method. Finally, we perform electromagnetic inversion for both conductivity and permeability to trace the distribution of magnetic nano-particles. Since these two parameters react differently according to the frequency range of sources, we can effectively describe the distribution of magnetic nano-particles by considering two parameters at the same time. Acknowledgements This work was supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP) and the Ministry of Trade, Industry & Energy(MOTIE) of the Republic of Korea (No. 20168510030830), and by the International Cooperation (No. 2012-8510030010) of KETEP, and by the Dual Use Technology Program, granted

  8. Pipeline modeling and assessment in unstable slopes

    Caceres, Carlos Nieves [Oleoducto Central S.A., Bogota, Cundinamarca (Colombia); Ordonez, Mauricio Pereira [SOLSIN S.A.S, Bogota, Cundinamarca (Colombia)

    2010-07-01

    The OCENSA pipeline system is vulnerable to geotechnical problems such as faults, landslides or creeping slopes, which are well-known in the Andes Mountains and tropical countries like Colombia. This paper proposes a methodology to evaluate the pipe behaviour during the soil displacements of slow landslides. Three different cases of analysis are examined, according to site characteristics. The process starts with a simplified analytical model and develops into 3D finite element numerical simulations applied to the on-site geometry of soil and pipe. Case 1 should be used when the unstable site is subject to landslides impacting significant lengths of pipeline, pipeline is straight, and landslide is simple from the geotechnical perspective. Case 2 should be used when pipeline is straight and landslide is complex (creeping slopes and non-conventional stabilization solutions). Case 3 should be used if the pipeline presents vertical or horizontal bends.

  9. Modeling of supermodes in coupled unstable resonators

    Townsend, S.S.

    1986-01-01

    A general formalism describing the supermodes of an array of N identical, circulantly coupled resonators is presented. The symmetry of the problem results in a reduction of the N coupled integral equations to N decoupled integral equations. Each independent integral equation defines a set of single-resonator modes derived for a hypothetical resonator whose geometry resembles a member of the real array with the exception that all coupling beams are replaced by feedback beams, each with a prescribed constant phase. A given array supermode consists of a single equivalent resonator mode appearing repetitively in each resonator with a prescribed relative phase between individual resonators. The specific array design chosen for example is that of N adjoint coupled confocal unstable resonators. The impact of coupling on the computer modeling of this system is discussed and computer results for the cases of two- and four-laser coupling are presented

  10. EOR increases 24% worldwide

    Moritis, G.

    1992-01-01

    Although the higher cost of enhanced oil recovery has taken its toll in projects, the Journal's worldwide EOR survey reveals that production from EOR is a significant and growing component of the world's oil production. This paper outlines hundreds of projects in 14 countries. Pilot, field wide, and planned projects are all included

  11. EOR by stimulated microflora

    Svarovskaya, L.I.; Altunina, L.K.; Rozhenkova, Z.A.; Bulavin, V.D. [Institute of Petroleum Chemistry, Tomsk (Russian Federation)

    1995-12-31

    A combined microbiological and physico-chemical method for EOR has been developed for flooded West Siberia oil fields with formation temperature of 45{degrees}-95{degrees}C (318-365K). Formation water includes rich and various biocenoses numbering up to 2 x 10{sup 7} cells per ml. Representatives of genera, i.e, Pseudomonas, Bacillus, Actinomyces, Micrococcus, Mycobacterium, Sarcina, etc. were found to be the most widely distributed microorganisms. The method is based on injection of systems exhibiting high oil displacing capacity and at the same time being an additional nitrous nutrient for endemic populations of microorganisms. Their injection into formation water favors biomass growth by 4-6 orders and promotes syntheses of biosurfactants, biopolymers, acids, etc., and gaseous products. The features of residual oil displacement have been studied on laboratory models using a combined microbiological and physico-chemical method. A curve for the yield of residual oil is presented by two peaks. The first peak is stipulated by the washing action of oil displacement system, and the second one by the effect of metabolites produced at stimulation of biogenic processes. Oil displacement index increases by 15%-30%.

  12. Integrated Reservoir Modeling of CO2-EOR Performance and Storage Potential in the Farnsworth Field Unit, Texas.

    Ampomah, W.; Balch, R. S.; Cather, M.; Dai, Z.

    2017-12-01

    We present a performance assessment methodology and storage potential for CO2 enhanced oil recovery (EOR) in partially depleted reservoirs. A three dimensional heterogeneous reservoir model was developed based on geological, geophysics and engineering data from Farnsworth field Unit (FWU). The model aided in improved characterization of prominent rock properties within the Pennsylvanian aged Morrow sandstone reservoir. Seismic attributes illuminated previously unknown faults and structural elements within the field. A laboratory fluid analysis was tuned to an equation of state and subsequently used to predict the thermodynamic minimum miscible pressure (MMP). Datasets including net-to-gross ratio, volume of shale, permeability, and burial history were used to model initial fault transmissibility based on Sperivick model. An improved history match of primary and secondary recovery was performed to set the basis for a CO2 flood study. The performance of the current CO2 miscible flood patterns was subsequently calibrated to historical production and injection data. Several prediction models were constructed to study the effect of recycling, addition of wells and /or new patterns, water alternating gas (WAG) cycles and optimum amount of CO2 purchase on incremental oil production and CO2 storage in the FWU. The history matching study successfully validated the presence of the previously undetected faults within FWU that were seen in the seismic survey. The analysis of the various prediction scenarios showed that recycling a high percentage of produced gas, addition of new wells and a gradual reduction in CO2 purchase after several years of operation would be the best approach to ensure a high percentage of recoverable incremental oil and sequestration of anthropogenic CO2 within the Morrow reservoir. Larger percentage of stored CO2 were dissolved in residual oil and less amount existed as supercritical free CO2. The geomechanical analysis on the caprock proved to an

  13. Stability analysis of uniform equilibrium foam states for EOR processes

    Ashoori, E.; Marchesin, D.; Rossen, W.R.

    2011-01-01

    The use of foam for mobility control is a promising mean to improve sweep efficiency in EOR. Experimental studies discovered that foam exhibits three different states (weak foam, intermediate foam, and strong foam). The intermediate-foam state is found to be unstable in the lab whereas the weak- and

  14. γ-unstable nuclei in the sdg boson model

    Kuyucak, S.; Lac, V-S.; Morrison, I.; Barret, B.R.

    1991-01-01

    Following the recent Pt(p,p') experiments which indicated the need for g bosons to reproduce the E4 data, we have extended the O(6) limit of the sd boson model to the sdg bosons. It is shown that a γ-unstable Hamiltonian in the sdg model consisting of a quadrupole interaction and a g boson energy leads to results that are very similar to the O(6) limit. Deviations from the empirical energy spectrum that stem from the γ-unstable nature of the Hamiltonian can be improved by including a consistent hexadecapole interaction which induces triaxiality. The same hexadecapole operator can also account for the strong E4 transitions to the 4 + states presumed to be g boson states. Specific applications are made to the Xe and Pt isotopes. 12 refs., 2 tabs., 4 figs

  15. gamma. -unstable nuclei in the sdg boson model

    Kuyucak, S.; Lac, V.S.; Morrison, I.; Barrett, B.R. (School of Physics, Univ. of Melbourne, Parkville (Australia))

    1991-07-18

    Following the recent Pt(p, p') experiments which indicated the need for g bosons to reproduce the E4 data, we have extended the O(6) limit of the sd boson model to include g bosons. It is shown that a {gamma}-unstable hamiltonian in the sdg model consisting of a quadrupole interaction and a g boson energy leads to results that are very similar to the O(6) limit. Deviations from the empirical energy spectrum that stem from the {gamma}-unstable nature of the hamiltonian can be improved by including a consistent hexadecapole interaction which induces triaxiality. The same hexadecapole operator can also account for the strong E4 transitions. Applications are made to the Xe and Pt isotopes. (orig.).

  16. Gamma-unstable nuclei in the sdg boson model

    Kuyucak, S.; Lac, V.-S.; Morrison, I.; Barret, B. R.

    Following the recent Pt(p,p') experiments which indicated the need for high angular momentum (g) bosons to reproduce the E4 data, we have extended the O(6) limit of the sd boson model to the sdg bosons. It is shown that a gamma-unstable Hamiltonian in the sdg model consisting of a quadrupole interaction and a g boson energy leads to results that are very similar to the O(6) limit. Deviations from the empirical energy spectrum that stem from the gamma-unstable nature of the Hamiltonian can be improved by including a consistent hexadecapole interaction which induces triaxiality. The same hexadecapole operator can also account for the strong E4 transitions to the 4(sup +) states presumed to be g boson states. Specific applications are made to the Xe and Pt isotopes.

  17. γ-unstable nuclei in the sdg boson model

    Kuyucak, S.; Lac, V.-S.; Morrison, I.; Barrett, B. R.

    1991-07-01

    Following the recent Pt(p, p‧) experiments which indicated the need for g bosons to reproduce the E4 data, we have extended the O(6) limit of the sd boson model to include g bosons. It is shown that a γ-unstable hamiltonian in the sdg model consisting of a quadrupole interaction and a g boson energy leads to results that are very similar to the O(6) limit. Deviations from the empirical energy spectrum that stem from the γ-unstable nature of the hamiltonian can be improved by including a consistent hexadecapole interaction which induces triaxiality. The same hexadecapole operator can also account for the strong E4 transitions. Applications are made to the Xe and Pt isotopes.

  18. Robust Output Model Predictive Control of an Unstable Rijke Tube

    Fabian Jarmolowitz

    2012-01-01

    Full Text Available This work investigates the active control of an unstable Rijke tube using robust output model predictive control (RMPC. As internal model a polytopic linear system with constraints is assumed to account for uncertainties. For guaranteed stability, a linear state feedback controller is designed using linear matrix inequalities and used within a feedback formulation of the model predictive controller. For state estimation a robust gain-scheduled observer is developed. It is shown that the proposed RMPC ensures robust stability under constraints over the considered operating range.

  19. Ambient vibrations of unstable rock slopes - insights from numerical modeling

    Burjanek, Jan; Kleinbrod, Ulrike; Fäh, Donat

    2017-04-01

    The recent events in Nepal (2015 M7.8 Gorkha) and New Zealand (2016 M7.8 Kaikoura) highlighted the importance of earthquake-induced landslides, which caused significant damages. Moreover, landslide created dams present a potential developing hazard. In order to reduce the costly consequences of such events it is important to detect and characterize earthquake susceptible rock slope instabilities before an event, and to take mitigation measures. For the characterisation of instable slopes, acquisition of ambient vibrations might be a new alternative to the already existing methods. We present both observations and 3D numerical simulations of the ambient vibrations of unstable slopes. In particular, models of representative real sites have been developed based on detailed terrain mapping and used for the comparison between synthetics and observations. A finite-difference code has been adopted for the seismic wave propagation in a 3D inhomogeneous visco-elastic media with irregular free surface. It utilizes a curvilinear grid for a precise modeling of curved topography and local mesh refinement to make computational mesh finer near the free surface. Topographic site effects, controlled merely by the shape of the topography, do not explain the observed seismic response. In contrast, steeply-dipping compliant fractures have been found to play a key role in fitting observations. Notably, the synthetized response is controlled by inertial mass of the unstable rock, and by stiffness, depth and network density of the fractures. The developed models fit observed extreme amplification levels (factors of 70!) and show directionality as well. This represents a possibility to characterize slope structure and infer depth or volume of the slope instability from the ambient noise recordings in the future.

  20. Model of the transverse modes of stable and unstable porro–prism resonators using symmetry considerations

    Burger, L

    2007-01-01

    Full Text Available of this type of resonator. Further use of the model reveals the formation of more complex beam patterns, and the nature of these patterns is investigated. Also, the output of stable and unstable resonator modes is presented....

  1. Managing geological uncertainty in CO2-EOR reservoir assessments

    Welkenhuysen, Kris; Piessens, Kris

    2014-05-01

    therefore not suited for cost-benefit analysis. They likely result in too optimistic results because onshore configurations are cheaper and different. We propose to translate the detailed US data to the North Sea, retaining their uncertainty ranges. In a first step, a general cost correction can be applied to account for costs specific to the EU and the offshore setting. In a second step site-specific data, including laboratory tests and reservoir modelling, are used to further adapt the EOR ratio values taking into account all available geological reservoir-specific knowledge. And lastly, an evaluation of the field configuration will have an influence on both the cost and local geology dimension, because e.g. horizontal drilling is needed (cost) to improve injectivity (geology). As such, a dataset of the EOR field is obtained which contains all aspects and their uncertainty ranges. With these, a geologically realistic basis is obtained for further cost-benefit analysis of a specific field, where the uncertainties are accounted for using a stochastic evaluation. Such ad-hoc evaluation of geological parameters will provide a better assessment of the CO2-EOR potential of the North Sea oil fields.

  2. Data Analysis and Neuro-Fuzzy Technique for EOR Screening: Application in Angolan Oilfields

    Geraldo A. R. Ramos

    2017-06-01

    Full Text Available In this work, a neuro-fuzzy (NF simulation study was conducted in order to screen candidate reservoirs for enhanced oil recovery (EOR projects in Angolan oilfields. First, a knowledge pattern is extracted by combining both the searching potential of fuzzy-logic (FL and the learning capability of neural network (NN to make a priori decisions. The extracted knowledge pattern is validated against rock and fluid data trained from successful EOR projects around the world. Then, data from Block K offshore Angolan oilfields are then mined and analysed using box-plot technique for the investigation of the degree of suitability for EOR projects. The trained and validated model is then tested on the Angolan field data (Block K where EOR application is yet to be fully established. The results from the NF simulation technique applied in this investigation show that polymer, hydrocarbon gas, and combustion are the suitable EOR techniques.

  3. Capillary filling rules and displacement mechanisms for spontaneous imbibition of CO2 for carbon storage and EOR using micro-model experiments and pore scale simulation

    Chapman, E.; Yang, J.; Crawshaw, J.; Boek, E. S.

    2012-04-01

    In the 1980s, Lenormand et al. carried out their pioneering work on displacement mechanisms of fluids in etched networks [1]. Here we further examine displacement mechanisms in relation to capillary filling rules for spontaneous imbibition. Understanding the role of spontaneous imbibition in fluid displacement is essential for refining pore network models. Generally, pore network models use simple capillary filling rules and here we examine the validity of these rules for spontaneous imbibition. Improvement of pore network models is vital for the process of 'up-scaling' to the field scale for both enhanced oil recovery (EOR) and carbon sequestration. In this work, we present our experimental microfluidic research into the displacement of both supercritical CO2/deionised water (DI) systems and analogous n-decane/air - where supercritical CO2 and n-decane are the respective wetting fluids - controlled by imbibition at the pore scale. We conducted our experiments in etched PMMA and silicon/glass micro-fluidic hydrophobic chips. We first investigate displacement in single etched pore junctions, followed by displacement in complex network designs representing actual rock thin sections, i.e. Berea sandstone and Sucrosic dolomite. The n-decane/air experiments were conducted under ambient conditions, whereas the supercritical CO2/DI water experiments were conducted under high temperature and pressure in order to replicate reservoir conditions. Fluid displacement in all experiments was captured via a high speed video microscope. The direction and type of displacement the imbibing fluid takes when it enters a junction is dependent on the number of possible channels in which the wetting fluid can imbibe, i.e. I1, I2 and I3 [1]. Depending on the experiment conducted, the micro-models were initially filled with either DI water or air before the wetting fluid was injected. We found that the imbibition of the wetting fluid through a single pore is primarily controlled by the

  4. The 1992 FRDM mass model and unstable nuclei

    Moeller, P.

    1994-01-01

    We discuss the reliability of a recent global nuclear-structure calculation in regions far from β stability. We focus on the results for nuclear masses, but also mention other results obtained in the nuclear-structure calculation, for example ground-state spins. We discuss what should be some minimal requirements of a nuclear mass model and study how the macroscopic-microscopic method and other nuclear mass models fullfil such basic requirements. We study in particular the reliability of nuclear mass models in regions of nuclei that were not considered in the determination of the model parameters

  5. New insight into unstable hillslopes hydrology from hydrogeochemical modelling.

    Bertrand, C.; Marc, V.; Malet, J.-P.

    2010-05-01

    In the black marl outcrops of the French South Alps, sub surface flow conditions are considered as the main triggering factor for initiation and reactivation of landslides. The problem is traditionally addressed in term of hydrological processes (how does percolation to the water table occur?) but in some cases the origin of water is also in question. Direct rainfall is generally assumed as the only water source for groundwater recharge in shallow hillslope aquifers. The bedrock is also supposed impervious and continuous. Yet the geological environment of the study area is very complex owing to the geological history of this alpine sector. The autochthonous callovo-oxfordian black marl bedrock is highly tectonized (Maquaire et al., 2003) and may be affected by large, possibly draining discontinuities. A deep water inflow at the slip surface may at least locally result in increase the pore pressure and decrease the effective shearing resistance of the landslide material. In the active slow-moving landslide of Super-Sauze (Malet and Maquaire, 2003), this question has been addressed using hydrochemical investigations. The groundwater was sampled during five field campaigns uniformly spread out over the year from a network of boreholes. Water chemistry data were completed by geochemical and mineralogical analyses of the marl material. The major hydro-geochemical processes over area proved (1) mixing processes, (2) pyrite alteration, (3) dissolution/precipitation of carbonates and (4) cations exchange (de Montety et al., 2007). A geochemical modelling was carried out using the model Phreeqc (Parkhurst and Appelo, version 2.15, 2008) to check how suitable was observed water chemistry with the reservoir characteristics. The modelling exercise was based on a kinetics approach of soil-water interactions. The model simulates the rock alteration by the dissolution of the primary minerals and the precipitation of new phases. Initial parameters were obtained from geochemical

  6. PD/PID controller tuning based on model approximations: Model reduction of some unstable and higher order nonlinear models

    Christer Dalen

    2017-10-01

    Full Text Available A model reduction technique based on optimization theory is presented, where a possible higher order system/model is approximated with an unstable DIPTD model by using only step response data. The DIPTD model is used to tune PD/PID controllers for the underlying possible higher order system. Numerous examples are used to illustrate the theory, i.e. both linear and nonlinear models. The Pareto Optimal controller is used as a reference controller.

  7. Economics show CO2 EOR potential in central Kansas

    Dubois, M.K.; Byrnes, A.P.; Pancake, R.E.; Willhite, G.P.; Schoeling, L.G.

    2000-01-01

    Carbon dioxide (CO2) enhanced oil recovery (EOR) may be the key to recovering hundreds of millions of bbl of trapped oil from the mature fields in central Kansas. Preliminary economic analysis indicates that CO2 EOR should provide an internal rate of return (IRR) greater than 20%, before income tax, assuming oil sells for \\$20/bbl, CO2 costs \\$1/Mcf, and gross utilization is 10 Mcf of CO2/bbl of oil recovered. If the CO2 cost is reduced to \\$0.75/Mcf, an oil price of $17/bbl yields an IRR of 20%. Reservoir and economic modeling indicates that IRR is most sensitive to oil price and CO2 cost. A project requires a minimum recovery of 1,500 net bbl/acre (about 1 million net bbl/1-mile section) under a best-case scenario. Less important variables to the economics are capital costs and non-CO2 related lease operating expenses.

  8. The economics of CO2-EOR cluster developments in the UK Central North Sea

    Kemp, Alexander G.; Kasim, Sola

    2013-01-01

    Studies to date have generally shown that individual CO 2 -EOR offshore projects are uneconomic except under questionable assumptions. The present study is based on an interconnected cluster of nine oilfields in the Central North Sea linked to an onshore CO 2 collection hub by a set of existing and new pipelines. Monte Carlo simulation modelling was undertaken of the prospective returns to investments in CO 2 -EOR in the fields. Relatively high oil prices were employed for the study period (2020–2050) and two contrasting CO 2 transfer price scenarios, the first being the Carbon Price Floor (CPF) introduced by the UK Government and the second being relatively low negotiated prices reflecting recent and prospective levels under the EU-ETS. At CPF prices the investment returns were all found to be negative, but at prices averaging £10 per tonne positive returns were generally achieved. The study emphasises the importance of CO 2 prices and the taxation system in determining the viability of the investments. - Highlights: • Detailed modelling of CO 2 EOR in nine North Sea oil fields. • Overall investment risks are demonstrated to be very high. • Sharing of pipelines in network and cluster of CO 2 -EOR fields significantly reduces investment costs. • Range of plausible CO 2 prices paid by investor results in very wide range of returns from CO 2 -EOR. • CO 2 pricing and tax arrangements for EOR need further attention by policy makers

  9. Challenges in modeling unstable two-phase flow experiments in porous micromodels

    Meheust, Y.; Ferrari, A.; Jimenez-Martinez, J.; Le Borgne, T.; Lunati, I.

    2014-12-01

    The simulation of unstable invasion patterns in porous media flow is challenging since small perturbations tend to grow in time, so that slight differences in geometry or initial conditions potentially give rise to significantly different solutions. Here we present a detailed comparison of pore scale simulations and experiments of unstable primary drainage in porous micromodels. The porous medium consists of a Hele-Shaw cell containing cylindrical obstacles. Two experimental flow cells have been constructed by soft lithography, with different degrees of heterogeneity in the grain size distribution. To model two-phase flow at the pore scale, we solve Navier-Stokes equations for mass and momentum conservation in the discretized pore space and employ the Volume of Fluid (VOF) method to track the evolution of the interface. During drainage, if the defending fluid is the most viscous, viscous forces destabilize the interface, giving rise to the formation of preferential flow paths, in the form of a branched fingering structure. We test different numerical models (a 2D vertical integrated model and a full 3D model) and different initial conditions, studying their impact on the simulated spatial distributions of the fluid phases. Although due to the unstable nature of the invasion, small discrepancies between the experimental setup and the numerical model can result in different fluids patterns (see figure), simulations show a satisfactory agreement with the structures observed experimentally. To estimate the ability of the numerical approach to reproduce unstable displacement, we compare several quantities in both the statistical and deterministic sense. We demonstrate the impact of three main sources of uncertainty : i) the uncertainty on the pore space geometry, ii) the interface initialization and ii) three dimensional effects [1]. Simulations in weakly heterogeneous geometries are found to be more challenging because uncertainties on pore neck widths are on the same

  10. Robust Model-based Control of Open-loop Unstable Processes

    Emad, Ali

    1999-01-01

    This paper addresses the development of new formulations for estimating modeling errors or unmeasured disturbances to be used in Model Predictive Control (MPC) algorithms during open-loop prediction. Two different formulations were developed in this paper. One is used in MPC that directly utilizes linear models and the other in MPC that utilizes non-linear models. These estimation techniques were utilized to provide robust performance for MPC algorithms when the plant is open-loop unstable and under the influence of modeling error and/or unmeasured disturbances. For MPC that utilizes a non-linear model, the estimation technique is formulated as a fixed small size on-line optimization problem, while for linear MPC, the unmeasured disturbances are estimated via a proposed linear disturbance model. The disturbance model coefficients are identified on-line from historical estimates of plant-model mismatch. The effectiveness of incorporating these proposed estimation techniques into MPC is tested through simulated implementation on non-linear unstable exothermic fluidized bed reactor. Closed-loop simulations proved the capability of the proposed estimation methods to stabilize and, thereby, improve the MPC performance in such cases. (Author)

  11. Simulation and Optimization of Foam EOR Processes

    Namdar Zanganeh, M.

    2011-01-01

    Chemical enhanced oil recovery (EOR) is relatively expensive due to the high cost of the injected chemicals such as surfactants. Excessive use of these chemicals leads to processes that are not economically feasible. Therefore, optimizing the volume of these injected chemicals is of extreme

  12. Monitoring of magnetic EOR fluids in reservoir under production by using the electromagnetic method

    KIM, S.; Min, D. J.; Moon, S.; Kim, W. K.; Shin, Y.

    2014-12-01

    To increase the amount of oil and gas extracted during production, some techniques like EOR (Enhanced Oil Recovery) are applied by injecting some materials such as water and CO2. Recently, there are some researches for injecting magnetic nanoparticles with fluids during EOR. The size of particle is nano-scale, which can prevent particles from adhering to the pores of reservoir. The main purpose of injecting magnetic nanoparticles is to monitor movement or distribution of EOR fluids. To monitor the injected magnetic EOR fluids in the reservoir, CSEM (controlled source electromagnetic method) can be the most optimized geophysical method among various geophysical monitoring methods. Depending on the reservoir circumstances, we can control the electric or magnetic sources to monitor reservoir during oil or gas production. In this study, we perform numerical simulation of CSEM for 3D horizontal-layered models assuming a reservoir under production. We suppose that there are two wells: one is for the controlled source; the other is for the receiver. By changing the distribution, movement and magnetization of EOR fluids, we compare the electric or magnetic fields recorded at the receiver. Maxwell's equations are the governing equation of CSEM and are approximated by using the edge-based finite-element method. Direct solver is applied to solve the linear equations. Because injected magnetic nanoparticle changes the conductivity of EOR fluid, there is high contrast of conductivity of reservoir. This high contrast of conductivity induces secondary electric or magnetic fields that are recorded at the receiver well. We compare these recorded secondary fields generated by various movement or distribution of magnetic EOR fluid. Acknowledgements This work was supported by the "Development of Technology for CO2 Marine Geological Storage" grant funded by the Ministry of Oceans and Fisheries of Korea, by the "Civil Military Technology Cooperation Center", and by the International

  13. Modeling and control of an unstable system using probabilistic fuzzy inference system

    Sozhamadevi N.

    2015-09-01

    Full Text Available A new type Fuzzy Inference System is proposed, a Probabilistic Fuzzy Inference system which model and minimizes the effects of statistical uncertainties. The blend of two different concepts, degree of truth and probability of truth in a unique framework leads to this new concept. This combination is carried out both in Fuzzy sets and Fuzzy rules, which gives rise to Probabilistic Fuzzy Sets and Probabilistic Fuzzy Rules. Introducing these probabilistic elements, a distinctive probabilistic fuzzy inference system is developed and this involves fuzzification, inference and output processing. This integrated approach accounts for all of the uncertainty like rule uncertainties and measurement uncertainties present in the systems and has led to the design which performs optimally after training. In this paper a Probabilistic Fuzzy Inference System is applied for modeling and control of a highly nonlinear, unstable system and also proved its effectiveness.

  14. Coupled Modeling of Flow, Transport, and Deformation during Hydrodynamically Unstable Displacement in Fractured Rocks

    Jha, B.; Juanes, R.

    2015-12-01

    Coupled processes of flow, transport, and deformation are important during production of hydrocarbons from oil and gas reservoirs. Effective design and implementation of enhanced recovery techniques such as miscible gas flooding and hydraulic fracturing requires modeling and simulation of these coupled proceses in geologic porous media. We develop a computational framework to model the coupled processes of flow, transport, and deformation in heterogeneous fractured rock. We show that the hydrocarbon recovery efficiency during unstable displacement of a more viscous oil with a less viscous fluid in a fractured medium depends on the mechanical state of the medium, which evolves due to permeability alteration within and around fractures. We show that fully accounting for the coupling between the physical processes results in estimates of the recovery efficiency in agreement with observations in field and lab experiments.

  15. Unstable spiral waves and local Euclidean symmetry in a model of cardiac tissue

    Marcotte, Christopher D.; Grigoriev, Roman O.

    2015-01-01

    This paper investigates the properties of unstable single-spiral wave solutions arising in the Karma model of two-dimensional cardiac tissue. In particular, we discuss how such solutions can be computed numerically on domains of arbitrary shape and study how their stability, rotational frequency, and spatial drift depend on the size of the domain as well as the position of the spiral core with respect to the boundaries. We also discuss how the breaking of local Euclidean symmetry due to finite size effects as well as the spatial discretization of the model is reflected in the structure and dynamics of spiral waves. This analysis allows identification of a self-sustaining process responsible for maintaining the state of spiral chaos featuring multiple interacting spirals

  16. Unstable spiral waves and local Euclidean symmetry in a model of cardiac tissue.

    Marcotte, Christopher D; Grigoriev, Roman O

    2015-06-01

    This paper investigates the properties of unstable single-spiral wave solutions arising in the Karma model of two-dimensional cardiac tissue. In particular, we discuss how such solutions can be computed numerically on domains of arbitrary shape and study how their stability, rotational frequency, and spatial drift depend on the size of the domain as well as the position of the spiral core with respect to the boundaries. We also discuss how the breaking of local Euclidean symmetry due to finite size effects as well as the spatial discretization of the model is reflected in the structure and dynamics of spiral waves. This analysis allows identification of a self-sustaining process responsible for maintaining the state of spiral chaos featuring multiple interacting spirals.

  17. Evidence for a continental unstable triple junction as an alternate model for Vrancea seismicity

    Besutiu, L.

    2002-01-01

    The Vrancea active seismic zone located in the bending area of Romanian Carpathians stands for a long time as a challenge to geoscientists all over the world. Deep seismicity in continental collision circumstances is rather rare and always constraints on dynamics of subduction. The pattern of the intermediate-depth seismicity in the Vrancea region suggests a confined prismatic nearly vertical seismic body. The small size and geometry of the seismic zone have made it difficult to interpret the kinematics of subduction and continental collision in the area. During the years, several models, almost all subduction-related, have more or less successfully tried to explain this phenomenon. The paper represents an attempt to explain the Vrancea intermediate depth seismicity starting from a new concept, as introduced by the plate tectonics theory: the triple junction. A continental unstable triple junction is proposed as an alternate model to explain the unusual seismicity in the Vrancea seismic area. Three tectonic plates / microplates seem to join in the region: East European Plate (EEP), Moesian microplate (MoP), and the Intra-Alpine microplate (IaP). Their edges are geophysically documented and their motion is evidenced. The differentiation in their relative velocities generated an unstable transform-transform-compression triple junction that determined the vertical collapse of the lithospheric segment to which the intermediate seismicity within Vrancea zone is associated. Three major plates' wedges bound the seismic body: Tornquist-Teissyere zone, Peceneaga-Camena fault, and Trans-Getica fault. Temperature accommodation phenomena associated to the sinking lithospheric body into the hotter upper mantle environment (such as convective cells, phase-transform processes, and devolatilization) could be responsible for the earthquakes occurrence. The problem of the missing subduction related volcanism within Vrancea triple junction (VTJ) area is definitely solved in the case

  18. Unstable patterns and robust synchronization in a model of motor pathway in birdsong

    Moukam Kakmeni, F.M.; Bowong, S.; Nana, L.; Kofane, T.C.

    2006-10-01

    This paper investigates the fundamental dynamical mechanism responsible for transition to chaos in periodically modulated Duffing-Van der Pol oscillator. It is shown that a modulationally unstable pattern appears into an initially stable motionless state. A further spatiotemporal transition occurs with a sharp interface from the selected stable pattern to a stabilized pattern or chaotic state. Also, the synchronization of the chaotic state of the model is investigated. The results are discussed in the context of generalized synchronization. The main idea is to construct an augmented dynamical system from the synchronization error system, which is itself uncertain. The advantage of this method over existing results is that the synchronization time is explicitly computed. Numerical simulations are provided to verify the operation of the proposed algorithm. (author)

  19. CO2-EOR:Approaching an NCNO classification

    Nunez-Lopez, Vanessa [The University of Texas at Austin; Gil-Egui, Ramon

    2017-09-20

    This presentation provides an overview of progress made under the sponsored project and provides valuable input into the following questions: 1. Is CO2-EOR a valid option for greenhouse gas emission reduction? 2. How do different injection strategies affect EOR's Carbon Balance? 3. What is the impact of different gas separation processes on EOR emissions? 4. What is the impact of the downstream emissions on the Carbon Balance?

  20. Enzymes for Enhanced Oil Recovery (EOR)

    Nasiri, Hamidreza

    2011-04-15

    Primary oil recovery by reservoir pressure depletion and secondary oil recovery by waterflooding usually result in poor displacement efficiency. As a consequence there is always some trapped oil remaining in oil reservoirs. Oil entrapment is a result of complex interactions between viscous, gravity and capillary forces. Improving recovery from hydrocarbon fields typically involves altering the relative importance of the viscous and capillary forces. The potential of many EOR methods depends on their influence on fluid/rock interactions related to wettability and fluid/fluid interactions reflected in IFT. If the method has the potential to change the interactions favorably, it may be considered for further investigation, i.e. core flooding experiment, pilot and reservoir implementation. Enzyme-proteins can be introduced as an enhanced oil recovery method to improve waterflood performance by affecting interactions at the oil-water-rock interfaces. An important part of this thesis was to investigate how selected enzymes may influence wettability and capillary forces in a crude oil-brine-rock system, and thus possibly contribute to enhanced oil recovery. To investigate further by which mechanisms selected enzyme-proteins may contribute to enhance oil recovery, groups of enzymes with different properties and catalytic functions, known to be interfacially active, were chosen to cover a wide range of possible effects. These groups include (1) Greenzyme (GZ) which is a commercial EOR enzyme and consists of enzymes and stabilizers (surfactants), (2) The Zonase group consists of two types of pure enzyme, Zonase1 and Zonase2 which are protease enzymes and whose catalytic functions are to hydrolyze (breakdown) peptide bonds, (3) The Novozyme (NZ) group consists of three types of pure enzyme, NZ2, NZ3 and NZ6 which are esterase enzymes and whose catalytic functions are to hydrolyze ester bonds, and (4) Alpha-Lactalbumin ( -La) which is an important whey protein. The effect of

  1. Emergence of unstable itinerant orbits in a recurrent neural network model

    Suemitsu, Yoshikazu; Nara, Shigetoshi

    2005-01-01

    A recurrent neural network model with time delay is investigated by numerical methods. The model functions as both conventional associative memory and also enables us to embed a new kind of memory attractor that cannot be realized in models without time delay, for example chain-ring attractors. This is attributed to the fact that the time delay extends the available state space dimension. The difference between the basin structures of chain-ring attractors and of isolated cycle attractors is investigated with respect to the two attractor pattern sets, random memory patterns and designed memory patterns with intended structures. Compared to isolated attractors with random memory patterns, the basins of chain-ring attractors are reduced considerably. Computer experiments confirm that the basin volume of each embedded chain-ring attractor shrinks and the emergence of unstable itinerant orbits in the outer state space of the memory attractor basins is discovered. The instability of such itinerant orbits is investigated. Results show that a 1-bit difference in initial conditions does not exceed 10% of a total dimension within 100 updating steps

  2. Albania, offshore subscribed, offering EOR opportunities

    Anon.

    1992-01-01

    This paper reports that Albania is starting a campaign to offer field development/enhanced recovery projects to foreign companies. The fields chosen for EOR projects and their producing lithologies are: Patos-Marinza, sandstone. Kucova-Arrza, sandstone. Gorisht-Kocul, limestone. Ballsh-Hekal, limestone. Cakran-Mollaj, limestone. Visoka, limestone. Delvina, limestone. Field locations mostly lie along Albania's Adriatic Sea coast. Oil production began in Albania in 1929, peaked at about 60,000 b/d in 1975 and has steadily fallen

  3. Fluid characterization for miscible EOR projects and CO2 sequestration

    Jessen, Kristian; Stenby, Erling Halfdan

    2007-01-01

    Accurate performance prediction of miscible enhanced-oil-recovery (EOR) projects or CO, sequestration in depleted oil and gas reservoirs relies in part on the ability of an equation-of-state (EOS) model to adequately represent the properties of a wide range of mixtures of the resident fluid...... in the data reduction and demonstrate that for some gas/oil systems, swelling tests do not contribute to a more accurate prediction of multicontact miscibility. Finally, we report on the impact that use of EOS models based on different characterization procedures can have on recovery predictions from dynamic...... and the injected fluid(s). The mixtures that form when gas displaces oil in a porous medium will, in many cases, differ significantly from compositions created in swelling tests and other standard pressure/volume/temperature (PVT) experiments. Multicontact experiments (e.g., slimtube displacements) are often used...

  4. Unstable volatility

    Casas, Isabel; Gijbels, Irène

    2012-01-01

    The objective of this paper is to introduce the break-preserving local linear (BPLL) estimator for the estimation of unstable volatility functions for independent and asymptotically independent processes. Breaks in the structure of the conditional mean and/or the volatility functions are common...... in Finance. Nonparametric estimators are well suited for these events due to the flexibility of their functional form and their good asymptotic properties. However, the local polynomial kernel estimators are not consistent at points where the volatility function has a break. The estimator presented...

  5. A model of the transverse modes of stable and unstable porro-prism resonators using symmetry considerations

    Burger, Liesl; Forbes, Andrew

    2007-09-01

    A simple model of a Porro prism laser resonator has been found to correctly predict the formation of the "petal" mode patterns typical of these resonators. A geometrical analysis of the petals suggests that these petals are the lowest-order modes of this type of resonator. Further use of the model reveals the formation of more complex beam patterns, and the nature of these patterns is investigated. Also, the output of stable and unstable resonator modes is presented.

  6. Proton scattering from unstable nuclei 20O, 30S, 34Ar: experimental study and models

    Khan, Elias

    2000-01-01

    Elastic and inelastic proton scattering from the unstable nuclei 20 O, 30 S and 34 Ar were measured in inverse kinematics at the Grand Accelerateur National d'Ions Lourds. Secondary beams of 20 O at 43 MeV/A, 30 S at 53 MeV/A and 34 Ar at 47 MeV/A impinged on a (CH 2 ) n target. Recoiling protons were detected in the silicon strip array MUST. Energies and angular distributions of the first 2 + and 3 - states were measured. A phenomenological analysis yields values of the deformation parameters β 2 and β 3 of 0.55 (6) and 0.35 (5) for 20 O, 0.32 (3) and 0.22 (4) for 30 S, 0.27 (2) and 0.39 (3) for 34 Ar, respectively, and allows the extraction of the ratio of neutron to proton transition matrix elements (M n /M p )/(N/Z) for 2 + states: 2.35 (37) for 20 O, 0.93 (20) for 30 S and 1.35 (28) for 34 Ar. Therefore the proton rich nuclei 30 S and 34 Ar show a 2 + excitation of isoscalar character whereas the excitation of 20 O is of isovector character. In order to perform a microscopic analysis of the data, we have developed a QRPA model, using three Skyrme interaction: SIII, SG2, SLy4. This model reproduces measured B(EL) values for the oxygen, sulfur and argon isotopic chains, whereas RPA calculations, which do not take pairing into account, underestimate these values. In the case of the QRPA model the energies of the first 2 + state are overestimated by about 1 MeV, but the evolution along the isotopic chains is well reproduced. (M n /M p )/(N/Z) ratios for the first 2 + state deduced from the microscopic analysis using QRPA are 1.98 for 20 O, 1.05 for 30 S and 1.00 for 34 Ar, in agreement with the conclusions of the phenomenological analysis. However important discrepancies are observed between the two types of analysis for other isotopes, in particular neutron rich argon and sulfur nuclei. (author)

  7. 21SSD: a new public 21-cm EoR database

    Eames, Evan; Semelin, Benoît

    2018-05-01

    With current efforts inching closer to detecting the 21-cm signal from the Epoch of Reionization (EoR), proper preparation will require publicly available simulated models of the various forms the signal could take. In this work we present a database of such models, available at 21ssd.obspm.fr. The models are created with a fully-coupled radiative hydrodynamic simulation (LICORICE), and are created at high resolution (10243). We also begin to analyse and explore the possible 21-cm EoR signals (with Power Spectra and Pixel Distribution Functions), and study the effects of thermal noise on our ability to recover the signal out to high redshifts. Finally, we begin to explore the concepts of `distance' between different models, which represents a crucial step towards optimising parameter space sampling, training neural networks, and finally extracting parameter values from observations.

  8. Evaluation of EOR processes using network models

    Winter, A; Larsen, J K [Danmarks Tekniske Universitet (Denmark); Krogsboell, A

    1998-06-01

    The summary of the work performed is as follows: The experiment with air and isopropanol indicates that in the capillary flow regime the invading cluster exhibits fractal structure. In particular, its fractal dimension is 1.82 which corresponds to the invasion percolating with trapping. The trapping is expected to appear in this experiment because changes in pressure are moderate and no compression of air is present; The experiment with water and oil exhibited no fractal structure; The bimodal- and uniform distributions of pore sizes of the lattice yield the same fractal dimension of the invading cluster. No structural differences of the simulated invading clusters were observed; The check board lattice involving high and low indices associated with lattice sites yields the fractal dimension of the invading cluster of 1.742; The lower the `density` of low indices in the correlated lattices, the closer is the fractal dimension of the invading cluster to 1.82. (au)

  9. Cosmology and unstable nuclei

    Schramm, D.N.

    1995-01-01

    Primordial nucleosynthesis has established itself as one of the three pillars of Big Bang cosmology. Many of the Big Bang Nucleosynthesis reactions involve unstable nuclei. Hence there is a tight relationship hetween the subject of this conference and cosmology. The prime role of unstable nuclei in cosmology is related to lithium synthesis and the lack of cosmological synthesis of Be and B. These nuclei will thus be focused upon. Nucleosynthesis involves comparing calculated abundances with observed abundances. In general, abundance determinations are dominated by systematic rather than statistical errors, and work on bounding systematics is crucial. The quark-hadron inspired inhomogeneous calculations now unanimously agree that only relatively small variations in Ω b are possible vis-a-vis the homogeneous model; hence the robustness of Ω b ∼0.05 is now apparent. (These calculations depend critically on unstable nuclei.) The above argues that the bulk of the baryons in the universe are not producing visible light. A comparison with the ROSAT cluster data is also shown to be consistent with the standard BBN model. Ω b ∼1 seems to be definitely excluded, so if Ω TOTAL =1, as some recent observations may hint, then non-baryonic dark matter is required. The implications of the recently reported halo microlensing events are discussed. In summary, it is argued that the physics of unstable nuclei affects the fundamental dark matter argument. ((orig.))

  10. A Full-Featured User Friendly CO2-EOR and Sequestration Planning Software

    Savage, Bill [Nitec LLC, Denver, CO (United States)

    2013-11-30

    A Full-Featured, User Friendly CO2-EOR and Sequestration Planning Software This project addressed the development of an integrated software solution that includes a graphical user interface, numerical simulation, visualization tools and optimization processes for reservoir simulation modeling of CO2-EOR. The objective was to assist the industry in the development of domestic energy resources by expanding the application of CO2-EOR technologies, and ultimately to maximize the CO2} sequestration capacity of the U.S. The software resulted in a field-ready application for the industry to address the current CO2-EOR technologies. The software has been made available to the public without restrictions and with user friendly operating documentation and tutorials. The software (executable only) can be downloaded from NITEC’s website at www.nitecllc.com. This integrated solution enables the design, optimization and operation of CO2-EOR processes for small and mid-sized operators, who currently cannot afford the expensive, time intensive solutions that the major oil companies enjoy. Based on one estimate, small oil fields comprise 30% of the of total economic resource potential for the application of CO2-EOR processes in the U.S. This corresponds to 21.7 billion barrels of incremental, technically recoverable oil using the current “best practices”, and 31.9 billion barrels using “next-generation” CO2-EOR techniques. The project included a Case Study of a prospective CO2-EOR candidate field in Wyoming by a small independent, Linc Energy Petroleum Wyoming, Inc. NITEC LLC has an established track record of developing innovative and user friendly software. The Principle Investigator is an experienced manager and engineer with expertise in software development, numerical techniques, and GUI applications. Unique, presently-proprietary NITEC technologies have been integrated

  11. Carbon balance of CO2-EOR for NCNO classification

    Nunez-Lopez, Vanessa [The University of Texas at Austin; Gil-Egui, Ramon; Gonzalez-Nicolas, Ana; Hovorka, Susan D

    2017-03-18

    The question of whether carbon dioxide enhanced oil recovery (CO2-EOR) constitutes a valid alternative for greenhouse gas emission reduction has been frequently asked by the general public and environmental sectors. Through this technology, operational since 1972, oil production is enhanced by injecting CO2 into depleted oil reservoirs in order displace the residual oil toward production wells in a solvent/miscible process. For decades, the CO2 utilized for EOR has been most commonly sourced from natural CO2 accumulations. More recently, a few projects have emerged where anthropogenic CO2 (A-CO2) is captured at an industrial facility, transported to a depleted oil field, and utilized for EOR. If carbon geologic storage is one of the project objectives, all the CO2 injected into the oil field for EOR could technically be stored in the formation. Even though the CO2 is being prevented from entering the atmosphere, and permanently stored away in a secured geologic formation, a question arises as to whether the total CO2 volumes stored in order to produce the incremental oil through EOR are larger than the CO2 emitted throughout the entire CO2-EOR process, including the capture facility, the EOR site, and the refining and burning of the end product. We intend to answer some of these questions through a DOE-NETL funded study titled “Carbon Life Cycle Analysis of CO2-EOR for Net Carbon Negative Oil (NCNO) Classification”. NCNO is defined as oil whose carbon emissions to the atmosphere, when burned or otherwise used, are less than the amount of carbon permanently stored in the reservoir in order to produce the oil. In this paper, we focus on the EOR site in what is referred to as a gate-to-gate system, but are inclusive of the burning of the refined product, as this end member is explicitly stated in the definition of NCNO. Finally, we use Cranfield, Mississippi, as a case study and come to the conclusion that the incremental oil produced is net carbon negative.

  12. An intermittent control model of flexible human gait using a stable manifold of saddle-type unstable limit cycle dynamics.

    Fu, Chunjiang; Suzuki, Yasuyuki; Kiyono, Ken; Morasso, Pietro; Nomura, Taishin

    2014-12-06

    Stability of human gait is the ability to maintain upright posture during walking against external perturbations. It is a complex process determined by a number of cross-related factors, including gait trajectory, joint impedance and neural control strategies. Here, we consider a control strategy that can achieve stable steady-state periodic gait while maintaining joint flexibility with the lowest possible joint impedance. To this end, we carried out a simulation study of a heel-toe footed biped model with hip, knee and ankle joints and a heavy head-arms-trunk element, working in the sagittal plane. For simplicity, the model assumes a periodic desired joint angle trajectory and joint torques generated by a set of feed-forward and proportional-derivative feedback controllers, whereby the joint impedance is parametrized by the feedback gains. We could show that a desired steady-state gait accompanied by the desired joint angle trajectory can be established as a stable limit cycle (LC) for the feedback controller with an appropriate set of large feedback gains. Moreover, as the feedback gains are decreased for lowering the joint stiffness, stability of the LC is lost only in a few dimensions, while leaving the remaining large number of dimensions quite stable: this means that the LC becomes saddle-type, with a low-dimensional unstable manifold and a high-dimensional stable manifold. Remarkably, the unstable manifold remains of low dimensionality even when the feedback gains are decreased far below the instability point. We then developed an intermittent neural feedback controller that is activated only for short periods of time at an optimal phase of each gait stride. We characterized the robustness of this design by showing that it can better stabilize the unstable LC with small feedback gains, leading to a flexible gait, and in particular we demonstrated that such an intermittent controller performs better if it drives the state point to the stable manifold, rather

  13. Results from the MWA EoR Experiment

    Webster, Rachel L.; MWA EoR Collaboration

    2018-05-01

    The MWA EoR is one of a small handful of experiments designed to detect the statistical signal from the Epoch of Reionisation. Each of these experiments has reached a level of maturity, where the challenges, in particular of foreground removal, are being more fully understood. Over the past decade, the MWA EoR Collaboration has developed expertise and an understanding of the elements of the telescope array, the end-to-end pipelines, ionospheric conditions, and and the foreground emissions. Sufficient data has been collected to detect the theoretically predicted EoR signal. Limits have been published regularly, however we still several orders of magnitude from a possible detection. This paper outlines recent progress and indicates directions for future efforts.

  14. Discerning in situ performance of an eor agent in the midst of geological uncertainty

    Fatemi, S.A.; Jansen, J.D.; Rossen, W.R.

    2015-01-01

    An enhanced-oil-recovery pilot test has multiple goals, among them to verify the properties of the EOR agent in situ. Given the complexity of EOR processes and the inherent uncertainty in the reservoir description, it is a challenge to discern the properties of the EOR agent in situ. We present a

  15. Status and scope for EOR development in Oman

    Al-Adawy, M.S.; Nandyal, M.

    1991-01-01

    In view of a significant STOIIP (3000 + million m 3 ) of medium/heavy oil (less than 31 degrees API), EOR development in Oman has been and remains a major strategic option in its challenge to increase recovery and to meet long term production requirements. The initial EOR Development Program (1980-89) of which results are highlighted in this paper was based on a series of pilots and tests to gain experience and reduce uncertainties prior to embarking on wider EOR application. The processes tested included Steam and Polymer Flooding in the Marmul field, Steam Soak in five South Oman heavy oil fields and Hot water Injection in the Qarn Alam field. A wide range of reservoir types, oil characteristics and reservoir drive mechanisms have been covered in this test program. The initial program has provided the necessary operating/technical knowledge to enable new projects to be better defined. In this paper an overview of future EOR scope taking into consideration the current oil economic climate is developed and presented

  16. Efficacy of orthotic immobilization of the unstable subaxial cervical spine of the elderly patient: investigation in a cadaver model

    Bednar, Drew A.

    2004-01-01

    Objective To assess the efficacy of soft, semirigid and hard cervical collars to immobilize the neck in a destabilized cadaver model. Design This is a laboratory experiment. Setting The anatomy research lab of McMaster University. Patients None. Fresh cadavers from elderly patients suffering terminal medical illness and free of cervical structural disease were studied. Interventions Destabilizing discoligamentous lesions of the neck were created in the cadavers. Radiographs were taken in maximum displacement in the prone, decubitus and side-bending positions, first unsupported and then with soft, semirigid and hard collars applied. Displacements in angulation and translation were measured from the radiographs. Outcome measures Radiographic displacement under gravity load. Results In all cases there was no effective limitation of pathological displacement, and in many cases displacement was increased after collar application. Conclusions Cervical collars do not effectively support the unstable neck, and may be ineffective in preventing pathological displacements. PMID:15362326

  17. Worldwide Comparison of CO₂-EOR Conditions: Comparison of fiscal and industrial conditions in seven global regions where CO₂-EOR is active or under consideration

    Brownsort, Peter

    2015-01-01

    Previous work within the Scottish Carbon Capture & Storage (SCCS) joint industry project (JIP) on carbon dioxide enhanced oil recovery (CO2-EOR) which looked at financial incentives for CO2-EOR in the United Kingdom (UK) suggested that development of an EOR project in the UK continental shelf area was most likely only to be considered by a super-major or multinational oil company (Durusut and Pershad, 2014). For such a project to be initiated the overall conditions for CO2-EOR – financial, po...

  18. Use of Robust z in Detecting Unstable Items in Item Response Theory Models

    Huynh, Huynh; Meyer, Patrick

    2010-01-01

    The first part of this paper describes the use of the robust z[subscript R] statistic to link test forms using the Rasch (or one-parameter logistic) model. The procedure is then extended to the two-parameter and three-parameter logistic and two-parameter partial credit (2PPC) models. A real set of data was used to illustrate the extension. The…

  19. Unstable periodic orbits and chaotic economic growth

    Ishiyama, K.; Saiki, Y.

    2005-01-01

    We numerically find many unstable periodic solutions embedded in a chaotic attractor in a macroeconomic growth cycle model of two countries with different fiscal policies, and we focus on a special type of the unstable periodic solutions. It is confirmed that chaotic behavior represented by the model is qualitatively and quantitatively related to the unstable periodic solutions. We point out that the structure of a chaotic solution is dissolved into a class of finite unstable periodic solutions picked out among a large number of periodic solutions. In this context it is essential for the unstable periodic solutions to be embedded in the chaotic attractor

  20. Study of the Bellman equation in a production model with unstable demand

    Obrosova, N. K.; Shananin, A. A.

    2014-09-01

    A production model with allowance for a working capital deficit and a restricted maximum possible sales volume is proposed and analyzed. The study is motivated by the urgency of analyzing well-known problems of functioning low competitive macroeconomic structures. The original formulation of the task represents an infinite-horizon optimal control problem. As a result, the model is formalized in the form of a Bellman equation. It is proved that the corresponding Bellman operator is a contraction and has a unique fixed point in the chosen class of functions. A closed-form solution of the Bellman equation is found using the method of steps. The influence of the credit interest rate on the firm market value assessment is analyzed by applying the developed model.

  1. Stochastic integrated vendor–buyer model with unstable lead time and setup cost

    Chandra K. Jaggi

    2011-01-01

    Full Text Available This paper presents a new vendor-buyer system where there are different objectives for both sides. The proposed method of this paper is different from the other previously published works since it considers different objectives for both sides. In this paper, the vendor’s emphasis is on the crashing of the setup cost, which not only helps him compete in the market but also provides better services to his customers; and the buyer’s aim is to reduce the lead time, which not only facilitates the buyer to fulfill the customers’ demand on time but also enables him to earn a good reputation in the market or vice versa. In the light of the above stated facts, an integrated vendor-buyer stochastic inventory model is also developed. The propsed model considers two cases for demand during lead time: Case (i Complete demand information, Case (ii Partial demand information. The proposed model jointly optimizes the buyer’s ordered quantity and lead time along with vendor’s setup cost and the number of shipments. The results are demonstrated with the help of numerical examples.

  2. Epigenetic oxidative redox shift (EORS) theory of aging unifies the free radical and insulin signaling theories.

    Brewer, Gregory J

    2010-03-01

    cycle of EORS. Examples from our work in the aging rodent brain as well as other aging models are provided. Copyright 2010 Elsevier Inc. All rights reserved.

  3. Radiographic, densitometric, and biomechanical effects of recombinant canine somatotropin in an unstable ostectomy gap model of bone healing in dogs

    Millis, D.L.; Wilkens, B.E.; Daniel, G.B.; Hubner, K.; Mathews, A.; Buonomo, F.C.; Patell, K.R.; Weigel, J.P.

    1998-01-01

    Objective: To determine the effect of recombinant canine somatotropin (STH) on radiographic, densitometric, and biomechanical aspects of bone healing using an unstable ostectomy gap model. Study Design: After an ostectomy of the midshaft radius, bone healing was evaluated over an 8-week period in control dogs (n = 4) and dogs receiving recombinant canine STH (n = 4). Animals Or Sample Population: Eight sexually intact female Beagle dogs, 4 to 5 years old. Methods: Bone healing was evaluated by qualitative and quantitative evaluation of serial radiographs every 2 weeks. Terminal dual-energy x-ray absorptiometry and three-point bending biomechanical testing were also performed. Results: Dogs receiving STH had more advanced radiographic healing of ostectomy sites. Bone area, bone mineral content, and bone density were two to five times greater at the ostectomy sites of treated dogs. Ultimate load at failure and stiffness were three and five times greater in dogs receiving STH. Conclusions: Using the ostectomy gap model, recombinant canine STH enhanced the radiographic, densitometric, and biomechanical aspects of bone healing in dogs. Clinical Relevance: Dogs at risk for delayed healing of fractures may benefit from treatment with recombinant canine STH

  4. CO₂-EOR Stakeholder Perceptions and Policy Responses

    Mabon, Leslie; Littlecott, Chris

    2015-01-01

    Across the investigations undertaken in WP1 and WP10, analysis has been made of eight different stakeholder constituencies and their perceptions of CO2-EOR. The stakeholder groups investigated include both members of the public and professional groups with direct interest in energy and / or climate change issues. WP1 started this analysis with an investigation of the perceptions and concerns of Scottish environmental NGOs during 2012-13. WP10 sought to test these findings via qualitative f...

  5. Small core flood experiments for foam EOR: Screening surfactant applications

    Jones, S.A.; Van der Bent, V.; Farajzadeh, R.; Rossen, W.R.; Vincent-Bonnieu, S.

    2015-01-01

    Aqueous foams are a means of increasing the sweep efficiency of enhanced oil recovery processes. An understanding of how a foam behaves in the presence of oil is therefore of great importance when selecting suitable surfactants for EOR processes. The consensus is currently that the most reliable method for determining the foam behavior in the presence of oil is to inject foam through a rock core. Coreflood tests, however, are typically carried out using large rock cores (e.g. diameter = 4 cm,...

  6. Using Horizontal Wells for Chemical EOR: Field Cases

    E. Delamaide

    2017-09-01

    Full Text Available Primary production of heavy oil in general only achieves a recovery of less than 10% OOIP. Waterflooding has been applied for a number of years in heavy oil pools and can yield much higher recovery but the efficiency of the process diminishes when viscosity is above a few hundreds cp with high water-cuts and the need to recycle significant volumes of water; in addition, significant quantities of oil are still left behind. To increase recovery beyond that, Enhanced Oil Recovery methods are needed. Thermal methods such as steam injection or Steam-Assisted Gravity Drainage (SAGD are not always applicable, in particular when the pay is thin and in that case chemical EOR can be an alternative. The two main chemical EOR processes are polymer and Alkali-Surfactant-Polymer (ASP flooding. The earlier records of field application of polymer injection in heavy oil fields date from the 1970’s however; the process had seen very few applications until recently. ASP in heavy oil has seen even fewer applications. A major specificity of chemical EOR in heavy oil is that the highly viscous oil bank is difficult to displace and that injectivity with vertical wells can be limited, particularly in thin reservoirs which are the prime target for chemical EOR. This situation has changed with the development of horizontal drilling and as a result, several chemical floods in heavy oil have been implemented in the past 10 years, using horizontal wells. The goal of this paper is to present some of the best documented field cases. The most successful and largest of these is the Pelican Lake polymer flood in Canada, operated by CNRL and Cenovus which is currently producing over 60,000 bbl/d. The Patos Marinza polymer flood by Bankers Petroleum in Albania and the Mooney project (polymer, ASP by BlackPearl (again in Canada are also worthy of discussion.

  7. Status of Foreground and Instrument Challenges for 21cm EoR experiments - Design Strategies for SKA and HERA

    Thyagarajan, Nithyanandan

    2018-05-01

    Direct detection of the Epoch of Reionization (EoR) via redshifted 21 cm line of H i will reveal the nature of the first stars and galaxies as well as revolutionize our understanding of a poorly explored evolutionary phase of the Universe. Projects such as the MWA, LOFAR, and PAPER commenced in the last decade with the promise of high significance statistical detection of the EoR, but have so far only weakly constrained models owing to unforeseen challenges from bright foreground sources and instrument systematics. It is essential for next generation instruments like the HERA and SKA to have these challenges addressed. I present an analysis of these challenges - wide-field measurements, antenna beam chromaticity, reflections in the instrument, and antenna position errors - along with performance specifications and design solutions that will be critical to designing successful next-generation instruments in enabling the first detection and also in placing meaningful constraints on reionization models.

  8. Manual control of unstable systems

    Allen, R. W.; Hogue, J. R.; Parseghian, Z.

    1986-01-01

    Under certain operational regimes and failure modes, air and ground vehicles can present the human operator with a dynamically unstable or divergent control task. Research conducted over the last two decades has explored the ability of the human operator to control unstable systems under a variety of circumstances. Past research is reviewed and human operator control capabilities are summarized. A current example of automobile directional control under rear brake lockup conditions is also reviewed. A control system model analysis of the driver's steering control task is summarized, based on a generic driver/vehicle model presented at last year's Annual Manual. Results from closed course braking tests are presented that confirm the difficulty the average driver has in controlling the unstable directional dynamics arising from rear wheel lockup.

  9. Design and implementation of a caustic flooding EOR pilot at Court Bakken heavy oil reservoir

    Xie, J.; Chung, B.; Leung, L. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Nexen Inc., Calgary, AB (Canada)

    2008-10-15

    Successful waterflooding has been ongoing since 1988 at the Court Bakken heavy oil field in west central Saskatchewan. There are currently 20 injectors and 28 active oil producers in the Court main unit which is owned by Nexen and Pengrowth. The Court pool has an estimated 103.8 mmbbl of original oil in place (OOIP), of which 24 per cent has been successfully recovered after 20 years of waterflooding. A high-level enhanced oil recovery (EOR) screening study was conducted to evaluate other EOR technologies for a heavy oil reservoir of this viscosity range (17 degrees API). Laboratory studies showed that caustic flooding may enhance oil recovery after waterflooding at the Court Bakken heavy oil pool. A single well test demonstrated that caustic injection effectively reduced residual oil saturation. A sector model reservoir simulation revealed that caustic flood could achieve 9 per cent incremental oil recovery in the pilot area. Following the promising laboratory results, a successful caustic flood pilot was implemented at Court heavy oil pool where the major challenges encountered were low reservoir pressure and water channeling. 6 refs., 2 tabs., 6 figs.

  10. Improving Chemical EOR Simulations and Reducing the Subsurface Uncertainty Using Downscaling Conditioned to Tracer Data

    Torrealba, Victor A.

    2017-10-02

    Recovery mechanisms are more likely to be influenced by grid-block size and reservoir heterogeneity in Chemical EOR (CEOR) than in conventional Water Flood (WF) simulations. Grid upscaling based on single-phase flow is a common practice in WF simulation models, where simulation grids are coarsened to perform history matching and sensitivity analyses within affordable computational times. This coarse grid resolution (typically about 100 ft.) could be sufficient in WF, however, it usually fails to capture key physical mechanisms in CEOR. In addition to increased numerical dispersion in coarse models, these models tend to artificially increase the level of mixing between the fluids and may not have enough resolution to capture different length scales of geological features to which EOR processes can be highly sensitive. As a result of which, coarse models usually overestimate the sweep efficiency, and underestimate the displacement efficiency. Grid refinement (simple downscaling) can resolve artificial mixing but appropriately re-creating the fine-scale heterogeneity, without degrading the history-match conducted on the coarse-scale, remains a challenge. Because of the difference in recovery mechanisms involved in CEOR, such as miscibility and thermodynamic phase split, the impact of grid downscaling on CEOR simulations is not well understood. In this work, we introduce a geostatistical downscaling method conditioned to tracer data to refine a coarse history-matched WF model. This downscaling process is necessary for CEOR simulations when the original (fine) earth model is not available or when major disconnects occur between the original earth model and the history-matched coarse WF model. The proposed downscaling method is a process of refining the coarse grid, and populating the relevant properties in the newly created finer grid cells. The method considers the values of rock properties in the coarse grid as hard data, and the corresponding variograms and property

  11. on GAGD EOR in Naturally Fractured Reservoirs

    Misagh Delalat

    2013-01-01

    Full Text Available The gas-assisted gravity drainage (GAGD process is designed and practiced based on gravity drainage idea and uses the advantage of density difference between injected CO2 and reservoir oil. In this work, one of Iran western oilfields was selected as a case study and a sector model was simulated based on its rock and fluid properties. The pressure of CO2 gas injection was close to the MMP of the oil, which was measured 1740 psia. Both homogeneous and heterogeneous types of fractures were simulated by creating maps of permeability and porosity. The results showed that homogeneous fractures had the highest value of efficiency, namely 40%; however, in heterogeneous fractures, the efficiency depended on the value of fracture density and the maximum efficiency was around 37%. Also, the effect of injection rate on two different intensities of fracture was studied and the results demonstrated that the model having higher fracture intensity had less limitation in increasing the CO2 injection rate; furthermore, its BHP did not increase intensively at higher injection rates either. In addition, three different types of water influxes were inspected on GAGD performance to simulate active, partial, and weak aquifer. The results showed that strong aquifer had a reverse effect on the influence of GAGD and almost completely disabled the gravity drainage mechanism. Finally, we inventively used a method to weaken the aquifer strength, and thus the gravity drainage revived and efficiency started to increase as if there was no aquifer.

  12. Biotechnology in petroleum recovery. The microbial EOR

    Sen, Ramkrishna [Department of Biotechnology, Indian Institute of Technology (IIT), Kharagpur, West Bengal 721302 (India)

    2008-12-15

    Biotechnology has played a significant role in enhancing crude oil recovery from the depleted oil reservoirs to solve stagnant petroleum production, after a three-stage recovery process employing mechanical, physical and chemical methods. Biotechnologically enhanced oil recovery processes, known as microbial enhanced oil recovery (MEOR), involve stimulating indigenous reservoir microbes or injecting specially selected consortia of natural bacteria into the reservoir to produce specific metabolic events that lead to improved oil recovery. This also involves flooding with oil recovery agents produced ex situ by industrial or pilot scale fermentation. This paper essentially reviews the operating mechanisms and the progress made in enhanced oil recovery through the use of microbes and their metabolic products. Improvement in oil recovery by injecting solvents and gases or by energizing the reservoir microflora to produce them in situ for carbonate rock dissolution and reservoir re-pressurization has been enunciated. The role of biosurfactants in oil mobilization through emulsification and that of biopolymers for selective plugging of oil-depleted zones and for biofilm formation have been delineated. The spoil sport played by sulfate-reducing bacteria (SRB) in MEOR has also been briefly reviewed. The importance of mathematical models used in predicting the applicability of an MEOR strategy and the microbial growth and transport has been qualitatively discussed. The results of some laboratory studies and worldwide field trials applying ex situ and in situ MEOR technologies were compiled and interpreted. However, the potential of the MEOR technologies has not been fully realized due to poor yield of the useful microbial metabolic products, growth inhibition by accumulated toxic metabolites and longer time of incubation. A complete evaluation and assessment of MEOR from an engineering standpoint based on economics, applicability and performance is required to further

  13. Tailor-made surfactants for optimized chemical EOR. Meeting oil reservoir conditions by applied knowledge of structure-performance relationship in extended surfactants

    Trahan, G.; Sorensen, W. [Sasol North America Inc., Westlake, LA (United States); Jakobs-Sauter, B. [Sasol Germany GmbH (Germany)

    2013-08-01

    Formulating the surfactant package for chemical EOR is a time consuming and expensive process - the formulation needs to fit the specific reservoir conditions (like oil type, temperature, salinity, etc.) to give optimum performance and the number of formulation variables is virtually endless. This paper studies the impact of surfactant structure on EOR formulation ability and performance and how to adjust the structure of the surfactant molecule to meet a specific reservoir's needs. Data from salinity phase boundary studies of alcohol propoxy sulfates illustrate how changes in alcohol structure as well as in propylene oxide level can shift optimum salinity and temperature to the desired range in a given model oil. From these data the impact of individual structural units was evaluated. Application of the HLD model (Hydrophilic-Lipophilic Deviation) shows how to extrapolate from the known data set to actual reservoir conditions. This is illustrated by studies on crude oil samples. Additional tests study how effective the selected surfactants perform. The HLD concept proves to be a valuable tool to select and tailor surfactants to individual reservoir needs, thus simplifying the surfactant screening process for EOR formulations by pre-selection of suitable structures and ultimately reducing cost and effort on the way to the most effective chemical EOR package. (orig.)

  14. Unstable slope management program.

    2009-08-01

    This Rapid Response Project gathered information on existing unstable slope management programs, with a : focus on asset management practices in the United States and overseas. On the basis of this study, the research : team summarized and recommende...

  15. Numerical modeling of flows and pollutant dispersion within and above urban street canyons under unstable thermal stratification by large-eddy simulation

    Chan, Ming-Chung; Liu, Chun-Ho

    2013-04-01

    Recently, with the ever increasing urban areas in developing countries, the problem of air pollution due to vehicular exhaust arouses the concern of different groups of people. Understanding how different factors, such as urban morphology, meteorological conditions and human activities, affect the characteristics of street canyon ventilation, pollutant dispersion above urban areas and pollutant re-entrainment from the shear layer can help us improve air pollution control strategies. Among the factors mentioned above, thermal stratification is a significant one determining the pollutant transport behaviors in certain situation, e.g. when the urban surface is heated by strong solar radiation, which, however, is still not widely explored. The objective of this study is to gain an in-depth understanding of the effects of unstable thermal stratification on the flows and pollutant dispersion within and above urban street canyons through numerical modeling using large-eddy simulation (LES). In this study, LES equipped with one-equation subgrid-scale (SGS) model is employed to model the flows and pollutant dispersion within and above two-dimensional (2D) urban street canyons (flanked by idealized buildings, which are square solid bars in these models) under different intensities of unstable thermal stratifications. Three building-height-to-street-width (aspect) ratios, 0.5, 1 and 2, are included in this study as a representation of different building densities. The prevailing wind flow above the urban canopy is driven by background pressure gradient, which is perpendicular to the street axis, while the condition of unstable thermal stratification is induced by applying a higher uniform temperature on the no-slip urban surface. The relative importance between stratification and background wind is characterized by the Richardson number, with zero value as a neutral case and negative value as an unstable case. The buoyancy force is modeled by Boussinesq approximation and the

  16. A variable-coefficient unstable nonlinear Schroedinger model for the electron beam plasmas and Rayleigh-Taylor instability in nonuniform plasmas: Solutions and observable effects

    Gao Yitian; Tian Bo

    2003-01-01

    A variable-coefficient unstable nonlinear Schroedinger model is hereby investigated, which arises in such applications as the electron-beam plasma waves and Rayleigh-Taylor instability in nonuniform plasmas. With computerized symbolic computation, families of exact analytic dark- and bright-soliton-like solutions are found, of which some previously published solutions turn out to be the special cases. Similarity solutions also come out, which are expressible in terms of the elliptic functions and the second Painleve transcendent. Some observable effects caused by the variable coefficient are predicted, which may be detected in the future with the relevant space or laboratory plasma experiments with nonuniform background existing

  17. Paradoxes of unstable electron

    Okun, L.B.; Zeldovich, Ya.B.

    1978-01-01

    The hypothesis that electron is unstable - when it is consistent with the vanishing mass of the photon- leads to a number of paradoxical statements. The lifetime of the electron is determined by emission of a huge number of longitudinal photons and exponentially depends on the amount of emitted energy. This suggests to discuss searches for charge nonconservation in experiments with high energy particles

  18. Externally perturbed unstable systems

    Posch, H.A.; Narnhofer, H.; Thirring, W.

    1991-01-01

    We discuss computer solutions of Newton's equation of motion for unstable systems in a container with time-dependent walls. An expansion leads to the formation of a cluster and a significant increase of the temperature. The question of entropy increase for expansion and compression of the system and the related problem of the feasibility of a perpetuum mobile of the second kind are investigated. (Authors)

  19. Nanoparticle-stabilized CO₂ foam for CO₂ EOR application

    Liu, Ning [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Lee, Robert [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Yu, Jianjia [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Li, Liangxiong [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Bustamante, Elizabeth [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Khalil, Munawar [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Mo, Di [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Jia, Bao [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Wang, Sai [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); San, Jingshan [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); An, Cheng [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States)

    2015-01-31

    The purpose of this project was to develop nanoparticle-stabilized CO₂ foam for CO₂ -EOR application, in which nanoparticles instead of surfactants are used for stabilizing CO₂ foam to improve the CO₂ sweep efficiency and increase oil recovery. The studies included: (1) investigation of CO₂ foam generation nanoparticles, such as silica nanoparticles, and the effects of particle concentration and surface properties, CO₂/brine ratio, brine salinity, pressure, and temperature on foam generation and foam stability; (2) coreflooding tests to understand the nanoparticle-stabilized CO₂ foam for waterflooded residual oil recovery, which include: oil-free coreflooding experiments with nanoparticle-stabilized CO₂ foam to understand the transportation of nanoparticles through the core; measurements of foam stability and CO₂ sweep efficiency under reservoir conditions to investigate temperature and pressure effects on the foam performance and oil recovery as well as the sweep efficiency in different core samples with different rock properties; and (3) long-term coreflooding experiments with the nanoparticle- stabilized CO₂ foam for residual oil recovery. Finally, the technical and economical feasibility of this technology was evaluated.

  20. Exhaustive Classification of the Invariant Solutions for a Specific Nonlinear Model Describing Near Planar and Marginally Long-Wave Unstable Interfaces for Phase Transition

    Ahangari, Fatemeh

    2018-05-01

    Problems of thermodynamic phase transition originate inherently in solidification, combustion and various other significant fields. If the transition region among two locally stable phases is adequately narrow, the dynamics can be modeled by an interface motion. This paper is devoted to exhaustive analysis of the invariant solutions for a modified Kuramoto-Sivashinsky equation in two spatial and one temporal dimensions is presented. This nonlinear partial differential equation asymptotically characterizes near planar interfaces, which are marginally long-wave unstable. For this purpose, by applying the classical symmetry method for this model the classical symmetry operators are attained. Moreover, the structure of the Lie algebra of symmetries is discussed and the optimal system of subalgebras, which yields the preliminary classification of group invariant solutions is constructed. Mainly, the Lie invariants corresponding to the infinitesimal symmetry generators as well as associated similarity reduced equations are also pointed out. Furthermore, the nonclassical symmetries of this nonlinear PDE are also comprehensively investigated.

  1. Monitoring of IOR/EOR operations by electrical prospecting; Denki tansaho ni yoru IOR/EOR monitoring

    Ushijima, K; Mizunaga, H; Ikeda, H; Masuda, K [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1996-10-01

    Fluid flow tomography (FFT) was developed to monitor enhanced oil recovery IOR/EOR operations. This method uses a casing pipe as linear current source by connecting a current electrode with a well inlet, and the other electrode is grounded at a point far different from the well. Potentials are rapidly measured at the same time by multi-channel receiving electrodes installed on the ground to obtain time series data composed of charged potential and superimposed spontaneous potential. After separation of both potentials, the charged potential data are processed by the conventional mise-a-la-masse method to extract local anomaly, determine the residual distribution and relative change distribution of time-sliced apparent resistivity, and obtain the 3-D profile of fluid. The spontaneous potential is also processed to obtain the deflection distribution of time-sliced potential at a specific time. Quantitative 3-D interpretation is conducted focusing attention on the generation mechanism of spontaneous potential. Behavior of underground permeated flow is determined as time series animation images to image fluid direction. This method was effective in real fields. 8 refs., 4 figs.

  2. Penn West Energy Trust CO{sub 2} EOR storage monitoring project

    Chalaturnyk, R. [Alberta Univ., Edmonton, AB (Canada)

    2007-07-01

    This presentation described Penn West Energy Trust's carbon dioxide (CO{sub 2}) enhanced oil recovery (EOR) storage monitoring project. The project formed part of a royalty credit program that offered a royalty reduction to energy companies as part of a plan to encourage the development of a CO{sub 2} storage industry in Alberta. The multi-agency project is expected to provide a better understanding of the fate of CO{sub 2} injected into petroleum reservoirs and the role that CO{sub 2} storage will play in reducing greenhouse gas (GHG) emissions. The project is located in a reservoir that had previously been waterflooded. High purity CO{sub 2} is injected through 2 directional wells. Data acquired from the field is used to provide information on baseline geology and hydrogeology, as well as to provide details of baseline leakages. Rock properties are investigated in order identify issues affecting rock strength. Geophysical monitoring is conducted to interpret baseline seismic profile datasets as well as to integrate active and passive survey analyses with geochemical characterization studies and reservoir models. The project is currently in the stage of developing a simulation model based on a comprehensive understanding of CO{sub 2} injection mechanisms. The model will be used to predict CO{sub 2} storage capacity and movement. refs., tabs., figs.

  3. The system-wide economics of a carbon dioxide capture, utilization, and storage network: Texas Gulf Coast with pure CO2-EOR flood

    King, Carey W.; Gülen, Gürcan; Cohen, Stuart M.; Nuñez-Lopez, Vanessa

    2013-09-01

    This letter compares several bounding cases for understanding the economic viability of capturing large quantities of anthropogenic CO2 from coal-fired power generators within the Electric Reliability Council of Texas electric grid and using it for pure CO2 enhanced oil recovery (EOR) in the onshore coastal region of Texas along the Gulf of Mexico. All captured CO2 in excess of that needed for EOR is sequestered in saline formations at the same geographic locations as the oil reservoirs but at a different depth. We analyze the extraction of oil from the same set of ten reservoirs within 20- and five-year time frames to describe how the scale of the carbon dioxide capture, utilization, and storage (CCUS) network changes to meet the rate of CO2 demand for oil recovery. Our analysis shows that there is a negative system-wide net present value (NPV) for all modeled scenarios. The system comes close to breakeven economics when capturing CO2 from three coal-fired power plants to produce oil via CO2-EOR over 20 years and assuming no CO2 emissions penalty. The NPV drops when we consider a larger network to produce oil more quickly (21 coal-fired generators with CO2 capture to produce 80% of the oil within five years). Upon applying a CO2 emissions penalty of 602009/tCO2 to fossil fuel emissions to ensure that coal-fired power plants with CO2 capture remain in baseload operation, the system economics drop significantly. We show near profitability for the cash flow of the EOR operations only; however, this situation requires relatively cheap electricity prices during operation.

  4. Production model in the conditions of unstable demand taking into account the influence of trading infrastructure: Ergodicity and its application

    Obrosova, N. K.; Shananin, A. A.

    2015-04-01

    A production model with allowance for a working capital deficit and a restricted maximum possible sales volume is proposed and analyzed. The study is motivated by an attempt to analyze the problems of functioning of low competitive macroeconomic structures. The model is formalized in the form of a Bellman equation, for which a closed-form solution is found. The stochastic process of product stock variations is proved to be ergodic and its final probability distribution is found. Expressions for the average production load and the average product stock are found by analyzing the stochastic process. A system of model equations relating the model variables to official statistical parameters is derived. The model is identified using data from the Fiat and KAMAZ companies. The influence of the credit interest rate on the firm market value assessment and the production load level are analyzed using comparative statics methods.

  5. Imaging unstable plaque

    SRIRANJAN, Rouchelle S.; TARKIN, Jason M.; RUDD, James H.; EVANS, Nicholas R.; CHOWDHURY, Mohammed M.

    2016-01-01

    Recent advances in imaging technology have enabled us to utilise a range of diagnostic approaches to better characterise high-risk atherosclerotic plaque. The aim of this article is to review current and emerging techniques used to detect and quantify unstable plaque in the context of large and small arterial systems and will focus on both invasive and non-invasive imaging techniques. While the diagnosis of clinically relevant atherosclerosis still relies heavily on anatomical assessment of arterial luminal stenosis, evolving multimodal cross-sectional imaging techniques that encompass novel molecular probes can provide added information with regard to plaque composition and overall disease burden. Novel molecular probes currently being developed to track precursors of plaque rupture such as inflammation, micro-calcification, hypoxia and neoangiogenesis are likely to have translational applications beyond diagnostics and have the potential to play a part in quantifying early responses to therapeutic interventions and more accurate cardiovascular risk stratification.

  6. Search for unstable photinos

    Mayer, P.

    1987-04-01

    We have searched in e + e - -annihilation for the photino, the partner of the photon, which is predicted by supersymmetry. Photinos can be pair produced in e + e - annihilation by the exchange of a scalar electron, the partner of the electron. It was assumed that the photino is unstable and decays in a photon and a lighter supersymmetric particle. This second particle leaves the detector unobserved. In the final state one sees then two photons with missing energy and missing momentum. The data were taken with the detector CELLO at the e + e - storage ring PETRA at DESY, Hamburg. The CMS energy was between 38.3 GeV and 46.8 GeV, the total luminosity was 38.3 pb -1 . The liquid argon lead calorimeter of CELLO, the most important part for this analysis, is specialised for the measurement of electromagnetic showers. It has a good space resolution and covers 96% of the solid angle of 4π. We have selected events with 2 photons in the central calorimeter, both with an energy of more than 2 GeV. The high background due to cosmic showers was reduced by accepting only events which were correlated to the time of the e + e - annihilation. Also the direction of the showers had to point to the interaction point. The applied cuts accepted the expected events with a probability P≅0.3. No event was found which was compatible with the production of unstable photinos. One can give limits on the mass of the photino, which depend on the mass of the scalar electron and on the decay path of the photino. In the simplest case, if all photinos decay at the interaction point, photinos with masses below 21 GeV are excluded (with a mass of the scalar electron below 40 GeV). (orig.) [de

  7. Model-based derivation, analysis and control of unstable microaerobic steady-states--considering Rhodospirillum rubrum as an example.

    Carius, Lisa; Rumschinski, Philipp; Faulwasser, Timm; Flockerzi, Dietrich; Grammel, Hartmut; Findeisen, Rolf

    2014-04-01

    Microaerobic (oxygen-limited) conditions are critical for inducing many important microbial processes in industrial or environmental applications. At very low oxygen concentrations, however, the process performance often suffers from technical limitations. Available dissolved oxygen measurement techniques are not sensitive enough and thus control techniques, that can reliable handle these conditions, are lacking. Recently, we proposed a microaerobic process control strategy, which overcomes these restrictions and allows to assess different degrees of oxygen limitation in bioreactor batch cultivations. Here, we focus on the design of a control strategy for the automation of oxygen-limited continuous cultures using the microaerobic formation of photosynthetic membranes (PM) in Rhodospirillum rubrum as model phenomenon. We draw upon R. rubrum since the considered phenomenon depends on the optimal availability of mixed-carbon sources, hence on boundary conditions which make the process performance challenging. Empirically assessing these specific microaerobic conditions is scarcely practicable as such a process reacts highly sensitive to changes in the substrate composition and the oxygen availability in the culture broth. Therefore, we propose a model-based process control strategy which allows to stabilize steady-states of cultures grown under these conditions. As designing the appropriate strategy requires a detailed knowledge of the system behavior, we begin by deriving and validating an unstructured process model. This model is used to optimize the experimental conditions, and identify properties of the system which are critical for process performance. The derived model facilitates the good process performance via the proposed optimal control strategy. In summary the presented model-based control strategy allows to access and maintain microaerobic steady-states of interest and to precisely and efficiently transfer the culture from one stable microaerobic steady

  8. PENENTUAN LAMA SULFONASI PADA PROSES PRODUKSI SURFAKTAN MES UNTUK APLIKASI EOR

    Mira Rivai

    2011-04-01

    Full Text Available For producing oil remains that remained at old oil wells (mature field, a method of advanced oil acquirement improvement known as an Enhanced Oil Recovery (EOR should be applied. Surfactant plays an important role in EOR process by reducing interfacial tension (IFT, altering wettability, reducing oil viscosity, and stabilizing dispersion to facilitate the process of oil jetting from reservoir to production well. To optimally cleanse oil that still remained a surfactant compatible with formation water and reservoir is needed. This study was conducted to get the best time of sulfonation process for producing MES surfactant with lower interfacial tension for EOR application. Results showed that the best times of sulfonation process with lower interfacial tension value were 3 and 4 hours

  9. Importance of fines in smart water enhanced oil recovery (SmW-EOR) for chalk outcrops

    Chakravarty, Krishna Hara; Fosbøl, Philip Loldrup; Thomsen, Kaj

    2015-01-01

    In SmW-EOR it is generally believed that precipitation of brines must be avoided since it can have a negative impact on the SmW sweep efficiency. But substitution of Mg2+ by Ca2+ on calcite surfaces (a well-accepted phenomenon) can change the brine combination and enhance the possibility of fine ......W-EOR experiments reported in literature. Both the amount of available soluble SO4 2- (aq) in the solution and the amount of CaSO4 precipitation has been calculated and correlated to the corresponding oil recovery.......In SmW-EOR it is generally believed that precipitation of brines must be avoided since it can have a negative impact on the SmW sweep efficiency. But substitution of Mg2+ by Ca2+ on calcite surfaces (a well-accepted phenomenon) can change the brine combination and enhance the possibility of fine...

  10. Structure and clusters of light unstable nuclei

    En'yo, Yoshiko

    2010-01-01

    As it is known, cluster structures are often observed in light nuclei. In the recent evolution of unstable nuclear research (on nuclei having unbalanced number of neutron and proton) further new types of clusters are coming to be revealed. In this report, structures of light unstable nuclei and some of the theoretical models to describe them are reviewed. The following topics are picked up. 1. Cluster structure and theoretical models, 2. Cluster structure of unstable nuclei (low excited state). 3. Cluster structure of neutron excess beryllium isotopes. 4. Cluster gas like state in C isotope. 5. Dineutron structure of He isotopes. Numbers of strange nuclear structures of light nuclei are illustrated. Antisymmetrized molecular dynamics (AMD) is the recently developed theoretical framework which has been successfully used in heavy ion reactions and nuclear structure studies. Successful application of AMD to the isotopes of Be, B and C are illustrated. (S. Funahashi)

  11. Dynamic behavior of potentially unstable soils and application of model for seismic risk reduction from liquefaction occurrence

    Sheshov, Vlatko

    2002-11-01

    Throughout the last decades, liquefaction phenomenon has been one of the most frequently discussed subjects in geotechnical earthquake engineering. Liquefaction has been a problem arousing considerable attention among the world scientists. The consequences from liquefaction occurrence have been present after each stronger earthquake. We have been witnesses of several strong earthquakes (Kobe - Japan, Chi Chi-Taiwan, Bhuj-India) that have occurred in the last decade. In these earthquakes, the liquefaction phenomenon caused severe damage to structures, loss of their functioning and indirect loss of human lives. Liquefaction as a phenomenon should not arouse fear but should call for serious elaboration and attention instead. The destructive nature of liquefaction could be mitigated, i.e., overcome in two ways: avoiding construction at locations characterized by high liquefaction potential which is not always possible and taking of measures for improvement of foundation soil. Finding out suitable measures for improvement of soil and thus mitigating the liquefaction potential has been the main incentive for the elaboration of this dissertation. The dissipation method involving the use of vertical drains as one of the measures for improvement of soils has been elaborated in details in this scientific work. The doctoral dissertation has been realized through experimental and analytical investigations. The experimental investigations done in the first phase represent model seismic shaking table tests of the efficiency of vertical drains (prefabricated and gravel drains). The analytical investigations in this phase have involved mathematical simulation of the effect of vertical drains upon pore pressure state during the experiments. The second phase of the experimental investigations has involved model tests of the behavior of pile foundations in soils susceptible to liquefaction with installed prefabricated drains. In this phase, the 'p - y' relationships have been

  12. Balancing for Unstable Nonlinear Systems

    Scherpen, J.M.A.

    1993-01-01

    A previously obtained method of balancing for stable nonlinear systems is extended to unstable nonlinear systems. The similarity invariants obtained by the concept of LQG balancing for an unstable linear system can also be obtained by considering a past and future energy function of the system. By

  13. Pole mass, width, and propagators of unstable fermions

    Kniehl, B.A.; Sirlin, A.

    2008-01-01

    The concepts of pole mass and width are extended to unstable fermions in the general framework of parity-nonconserving gauge theories, such as the Standard Model. In contrast with the conventional on-shell definitions, these concepts are gauge independent and avoid severe unphysical singularities, properties of great importance since most fundamental fermions in nature are unstable particles. General expressions for the unrenormalized and renormalized dressed propagators of unstable fermions and their field-renormalization constants are presented. (orig.)

  14. Dual action of high estradiol doses on MNU-induced prostate neoplasms in a rodent model with high serum testosterone: Protective effect and emergence of unstable epithelial microenvironment.

    Gonçalves, Bianca F; de Campos, Silvana G P; Góes, Rejane M; Scarano, Wellerson R; Taboga, Sebastião R; Vilamaior, Patricia S L

    2017-06-01

    Estrogens are critical players in prostate growth and disease. Estrogen therapy has been the standard treatment for advanced prostate cancer for several decades; however, it has currently been replaced by alternative anti-androgenic therapies. Additionally, studies of its action on prostate biology, resulting from an association between carcinogens and estrogen, at different stages of life are scarce or inconclusive about its protective and beneficial role on induced-carcinogenesis. Thus, the aim of this study was to determine whether estradiol exerts a protective and/or stimulatory role on N-methyl-N-nitrosurea-induced prostate neoplasms. We adopted a rodent model that has been used to study induced-prostate carcinogenesis: the Mongolian gerbil. We investigated the occurrence of neoplasms, karyometric patterns, androgen and estrogen receptors, basal cells, and global methylation status in ventral and dorsolateral prostate tissues. Histopathological analysis showed that estrogen was able to slow tumor growth in both lobes after prolonged treatment. However, a true neoplastic regression was observed only in the dorsolateral prostate. In addition to the protective effects against neoplastic progression, estrogen treatment resulted in an epithelium that exhibited features distinctive from a normal prostate, including increased androgen-insensitive basal cells, high androgens and estrogen receptor positivity, and changes in DNA methylation patterns. Estrogen was able to slow tumor growth, but the epithelium exhibited features distinct from a normal prostatic epithelium, and this unstable microenvironment could trigger lesion recurrence over time. © 2017 Wiley Periodicals, Inc.

  15. Can Producing Oil Store Carbon? Greenhouse Gas Footprint of CO2EOR, Offshore North Sea.

    Stewart, R Jamie; Haszeldine, R Stuart

    2015-05-05

    Carbon dioxide enhanced oil recovery (CO2EOR) is a proven and available technology used to produce incremental oil from depleted fields while permanently storing large tonnages of injected CO2. Although this technology has been used successfully onshore in North America and Europe, there are currently no CO2EOR projects in the United Kingdom. Here, we examine whether offshore CO2EOR can store more CO2 than onshore projects traditionally have and whether CO2 storage can offset additional emissions produced through offshore operations and incremental oil production. Using a high-level Life Cycle system approach, we find that the largest contribution to offshore emissions is from flaring or venting of reproduced CH4 and CO2. These can already be greatly reduced by regulation. If CO2 injection is continued after oil production has been optimized, then offshore CO2EOR has the potential to be carbon negative--even when emissions from refining, transport, and combustion of produced crude oil are included. The carbon intensity of oil produced can be just 0.056-0.062 tCO2e/bbl if flaring/venting is reduced by regulation. This compares against conventional Saudi oil 0.040 tCO2e/bbl or mined shale oil >0.300 tCO2e/bbl.

  16. Fractional Flow Theory Applicable to Non-Newtonian Behavior in EOR Processes

    Rossen, W.R.; Venkatraman, A.; Johns, R.T.; Kibodeaux, K.R.; Lai, H.; Moradi Tehrani, N.

    2011-01-01

    The method of characteristics, or fractional-flow theory, is extremely useful in understanding complex Enhanced Oil Recovery (EOR) processes and in calibrating simulators. One limitation has been its restriction to Newtonian rheology except in rectilinear flow. Its inability to deal with

  17. Effects of particle shape and size on nanofluid properties for potential Enhanced Oil Recovery (EOR

    Tengku Mohd Tengku Amran

    2016-01-01

    Full Text Available Application of Enhanced Oil Recovery (EOR in oil and gas industry is very important to increase oil recovery and prolong the lifetime of a reservoir but it has been very costly and losing properties of EOR agent due to harsh condition. Nanoparticles have been used in EOR application since they are not degradable in reservoir condition and used in smaller amount compared to polymer usage. Commonly, EOR techniques are focusing on increasing the sweep efficiency by controlling the mobility ratio between reservoir fluid and injected fluid. Thus, this research aimed to analyze the nanofluid viscosity at different particle size and shape, volumetric concentration and types of dispersing fluid, as well as to determine the oil recovery performance at different nanofluid concentration. The nanofluid viscosity was investigated at nanoparticle sizes of 15nm and 60nm and shapes of 15nm spherical-solid and porous. Five nanofluid samples with concentration ranging from 0.1wt.% to 7wt.% were used to investigate the effect of volumetric concentration. Distilled water, ethanol, ethylene glycol (EG and brine were used for the effect of dispersing fluids. Oil recovery was investigated at five different concentrations of nanofluid samples through flooding test. It was found that viscosity of nanofluid increased with decreasing particle size and increasing volumetric concentration. Solid shape particle and increasing dispersing fluid viscosity resulted in higher nanofluid viscosity. The higher the nanofluid concentration, the higher the oil recovery obtained. It can be concluded that nanofluid properties have been significantly affected by the environment and the particle used for potential EOR application.

  18. Socio-economic analysis of CCS/EOR in Denmark; Samfundsoekonomisk analyse af CCS/EOR i Danmark

    NONE

    2012-12-15

    The Danish Energy Agency has initiated an analysis of the socio-economic sustainability of a CCS / EOR system based on CO{sub 2} capture from Danish sources and injected into selected Danish North Sea oil fields. The analysis shall assess the socioeconomic consequences of such a project as well as highlight the budgetary economic effects for the parties involved. Taking into account a realistic time frame for conversion of the cogeneration power plants and for the extent of the possible capture of CO{sub 2} in each of these plants, it has been chosen only to presuppose the establishment of CCS in three plants, namely Studstrupvaerket, Fynsvaerket and Nordjyllandsvaerket. Only the oil fields Dan, Halfdan and Gorm were selected for the analysis. The analysis shows that in the selected oil fields it is possible to increase the oil production by approx. 151 million. barrels of oil to the year 2049, which corresponds to approx. 40% of the estimated potential in these fields. The increased oil production requires that approx. 95 million. tonnes of CO{sub 2} is captured in the three power plants, which are subsequently transported and injected in the oil fields in the North Sea. The transport of CO{sub 2} from the CHP plants to the North Sea are assumed to be done by ship, since this solution is economically favorable and also offers logistical advantages and increased flexibility. The analysis shows that both the budget economic and the socio-economic analysis as a whole provide a positive economic net present value over a 30-year period. The socio-economic benefit is expected to be about. 3.5 billion DKK higher. This difference is due to especially the following conditions: a) CO{sub 2} emissions of CO{sub 2} transport are only included in the socio-economic analysis, since shipping is outside the quota system. In the socio-economic analysis, the estimated value of damage impact on the environment is included; b) The value of the oil produced after 2049 is included in

  19. Proton scattering from unstable nuclei

    Recent improvements in the intensities and optical qualities of radioactive beams have made ... The quality of the data obtained are illustrated with recent results obtained at the GANIL facility for unstable oxygen, sulfur and argon isotopes.

  20. Isotope shifts in unstable nuclei

    Rebel, H.

    1980-05-01

    Current experimental investigations of isotope shifts in atomic spectra of unstable nuclei and the resulting information about size and shape of nuclei far off stability are discussed with reference to some representative examples. (orig.)

  1. Two dimensional unstable scar statistics.

    Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Kotulski, Joseph Daniel; Lee, Kelvin S. H. (ITT Industries/AES Los Angeles, CA)

    2006-12-01

    This report examines the localization of time harmonic high frequency modal fields in two dimensional cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This paper examines the enhancements for these unstable orbits when the opposing mirrors are both convex and concave. In the latter case the construction includes the treatment of interior foci.

  2. Experimental study on electromagnetic-assisted ZnO nanofluid flooding for enhanced oil recovery (EOR)

    Ahmad Latiff, Noor Rasyada; Alnarabiji, Mohamad Sahban

    2018-01-01

    Recently, nano-EOR has emerged as a new frontier for improved and enhanced oil recovery (IOR & EOR). Despite their benefits, the nanoparticles tend to agglomerate at reservoir conditions which cause their detachment from the oil/water interface, and are consequently retained rather than transported through a porous medium. Dielectric nanoparticles including ZnO have been proposed to be a good replacement for EOR due to their high melting point and thermal properties. But more importantly, these particles can be polarized under electromagnetic (EM) irradiation, which provides an innovative smart Nano-EOR process denoted as EM-Assisted Nano-EOR. In this study, parameters involved in the oil recovery mechanism under EM waves, such as reducing mobility ratio, lowering interfacial tensions (IFT) and altering wettability were investigated. Two-phase displacement experiments were performed in sandpacks under the water-wet condition at 95°C, with permeability in the range of 265–300 mD. A crude oil from Tapis oil field was employed; while ZnO nanofluids of two different particle sizes (55.7 and 117.1 nm) were prepared using 0.1 wt. % nanoparticles that dispersed into brine (3 wt. % NaCl) along with SDBS as a dispersant. In each flooding scheme, three injection sequential scenarios have been conducted: (i) brine flooding as a secondary process, (ii) surfactant/nano/EM-assisted nano flooding, and (iii) second brine flooding to flush nanoparticles. Compare with surfactant flooding (2% original oil in place/OOIP) as tertiary recovery, nano flooding almost reaches 8.5–10.2% of OOIP. On the other hand, EM-assisted nano flooding provides an incremental oil recovery of approximately 9–10.4% of OOIP. By evaluating the contact angle and interfacial tension, it was established that the degree of IFT reduction plays a governing role in the oil displacement mechanism via nano-EOR, compare to mobility ratio. These results reveal a promising way to employ water-based ZnO nanofluid

  3. Experimental study on electromagnetic-assisted ZnO nanofluid flooding for enhanced oil recovery (EOR).

    Adil, Muhammad; Lee, Keanchuan; Mohd Zaid, Hasnah; Ahmad Latiff, Noor Rasyada; Alnarabiji, Mohamad Sahban

    2018-01-01

    Recently, nano-EOR has emerged as a new frontier for improved and enhanced oil recovery (IOR & EOR). Despite their benefits, the nanoparticles tend to agglomerate at reservoir conditions which cause their detachment from the oil/water interface, and are consequently retained rather than transported through a porous medium. Dielectric nanoparticles including ZnO have been proposed to be a good replacement for EOR due to their high melting point and thermal properties. But more importantly, these particles can be polarized under electromagnetic (EM) irradiation, which provides an innovative smart Nano-EOR process denoted as EM-Assisted Nano-EOR. In this study, parameters involved in the oil recovery mechanism under EM waves, such as reducing mobility ratio, lowering interfacial tensions (IFT) and altering wettability were investigated. Two-phase displacement experiments were performed in sandpacks under the water-wet condition at 95°C, with permeability in the range of 265-300 mD. A crude oil from Tapis oil field was employed; while ZnO nanofluids of two different particle sizes (55.7 and 117.1 nm) were prepared using 0.1 wt. % nanoparticles that dispersed into brine (3 wt. % NaCl) along with SDBS as a dispersant. In each flooding scheme, three injection sequential scenarios have been conducted: (i) brine flooding as a secondary process, (ii) surfactant/nano/EM-assisted nano flooding, and (iii) second brine flooding to flush nanoparticles. Compare with surfactant flooding (2% original oil in place/OOIP) as tertiary recovery, nano flooding almost reaches 8.5-10.2% of OOIP. On the other hand, EM-assisted nano flooding provides an incremental oil recovery of approximately 9-10.4% of OOIP. By evaluating the contact angle and interfacial tension, it was established that the degree of IFT reduction plays a governing role in the oil displacement mechanism via nano-EOR, compare to mobility ratio. These results reveal a promising way to employ water-based ZnO nanofluid for

  4. Unstable baryons without Guts

    Uschersohn, J.; Elbaz, E.

    1983-01-01

    In the rishon model the leptons and the quarks can be classified in either doublets or quadruplets of a SU(2) group. Gauge invariance leads to different charged current interactions in the doublet and the quadruplet cases. Demanding that the neutral currents be the same in the two cases, one obtains relations between the different charged current couplings to leptons and quark; moreover, if these transform as linear combinations of doublets and quadruplets, one can estimate the mass of the gauge boson responsible for baryon decay to be not larger than 10 5 GeV. A SU(2)sub(L) x U(1) model is treated in detail

  5. EoR imaging with the SKA: the challenge of foreground removal

    Bonaldi, Anna

    2018-05-01

    21-cm observations of the Cosmic dawn (CD) and Epoch of Reionization (EoR) are one of the high priority science objectives for SKA Low. One of the most difficult aspects of the 21-cm measurement is the presence of foreground emission, due to our Galaxy and extragalactic sources, which is about four orders of magnitude brighter than the cosmological signal. While end-to-end simulations are being produced to investigate in details the foreground subtraction strategy, it is useful to complement this thorough but time-consuming approach with simpler, quicker ways to evaluate performance and identify possible critical steps. In this work, I present a forecast method, based on Bonaldi et al. (2015), Bonaldi & Ricciardi (2011), to understand the level of residual contamination after a component separation step, and its impact on our ability to investigate CD and EoR.

  6. Current Status of the LOFAR EoR Key Science Project

    Koopmans, L. V. E.; LOFAR EoR KSP Team

    2018-05-01

    A short status update on the LOFAR Epoch of Reionization (EoR) Key Science Project (KSP) is given, regarding data acquisition, data processing and analysis, and current power-spectrum limits on the redshifted 21-cm signal of neutral hydrogen at redshifts z = 8 - 10. With caution, we present a preliminary astrophysical analysis of ~60 hr of processed LOFAR data and their resulting power spectrum, showing that potentially already interesting limits on X-ray heating during the Cosmic Dawn can already be gained. This is by no means the final analysis of this sub-set of data, but illustrates the future potential when all nearly 3000 hr of data in hand on two EoR windows will have been processed.

  7. Application of fractal theory in refined reservoir description for EOR pilot area

    Yue Li; Yonggang Duan; Yun Li; Yuan Lu

    1997-08-01

    A reliable reservoir description is essential to investigate scenarios for successful EOR pilot test. Reservoir characterization includes formation composition, permeability, porosity, reservoir fluids and other petrophysical parameters. In this study, various new tools have been applied to characterize Kilamayi conglomerate formation. This paper examines the merits of various statistical methods for recognizing rock property correlation in vertical columns and gives out methods to determine fractal dimension including R/S analysis and power spectral analysis. The paper also demonstrates that there is obvious fractal characteristics in conglomerate reservoirs of Kilamayi oil fields. Well log data in EOR pilot area are used to get distribution profile of parameters including permeability, porosity, water saturation and shale content.

  8. Prediction of fluid phase behaviors in a CO{sub 2}-EOR process in Weyburn Field, Saskatchewan, Canada

    Zhao, L.; Law, D.H.S. [Alberta Research Council, Edmonton, AB (Canada); Freitag, N.; Huang, S. [Saskatchewan Research Council, Regina, SK (Canada)

    2005-07-01

    The mechanisms of enhanced oil recovery (EOR) and carbon dioxide (CO{sub 2}) storage in an oil depleted reservoir are being studied at the International Energy Agency's (IEA) Weyburn CO2 Monitoring and Storage Project in Saskatchewan. One of the objectives of this multi-disciplinary project has been to develop a Pressure-Volume-Temperature (PVT) model for the CO{sub 2}-Weyburn oil system that can be coupled with compositional reservoir models for short- and long-term field-scale reservoir simulations. In order to assess the long term risk of carbon dioxide (CO{sub 2}) injection for the purpose of EOR, it is important to accurately predict the CO{sub 2} distribution in different phases in the reservoir (aqueous, oleic and gaseous). The newly developed seven-component PVT model for Weyburn oil was based on measurements of phase-behavior properties such as oil density, viscosity, gas-oil ratio, saturation pressure and minimum miscibility pressure from oil samples collected from wells in different parts of the reservoir. The Peng-Robinson equation of state was used for the PVT model development and CO{sub 2} solubility in water was described by Henry's Law. Estimations of mineral trapping, ionic trapping and solubility trapping of CO{sub 2} are based on the amount of CO{sub 2} stored in the aqueous phase, but the amount of CO{sub 2} stored in the gaseous phase, which is the most mobile phase of CO{sub 2} in the reservoir, is essential in the estimation of CO{sub 2} leakage. The model was continuously modified as the field process proceeded in order to identify the dynamic change in fluid properties and the effect of contaminants in the injecting CO{sub 2}. The model, coupled with a compositional reservoir model, was used to predict the CO{sub 2} distribution and storage performance in the Weyburn field. 2 refs., 4 tabs., 8 figs.

  9. Rheological evaluation of polymers for EOR. Proper procedures for a laboratory approach

    Kouchaki, S.; Hincapie-Reina, R.; Ganzer, L. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE

    2013-08-01

    Some discrepancies exist in the literature concerning polymer EOR (Enhanced Oil Recovery) evaluation. Laboratory investigations are essentials for every particular flooding project, with proper preliminary lab evaluation techniques in order to study the polymer behavior and rheological properties at different reservoir conditions. Different research has been shown variation in procedures during polymer preparation and filtration; affecting the result in the field. Experience from field observation indicates that even high molecular weight (MW) polymers have filtration ratio (F.R) less than 1,5; in that way polymer solutions that are still in range cannot show a good approximation to the field behavior. To deal with the discrepancies, specific procedures based in rheological polymer characterization were adapted. Two different polymers were used for rheology study using a rotational rheometer analyzing some solutions at different conditions. Additionally rheological measurements was used to characterize the apparent viscosity of polymer as a shear rate function, salinity, temperature and polymer concentration, defining additional useful values for simulation evaluations and additionally Newtonian, non-Newtonian, shear viscosity and MW impact were also investigated. Quality control of the solutions was not limited to the conventional indicator 'filtrations ratio', but it was showed how important it is to consider two qualities check indicators, filterability ratio and filterability plot, simultaneously. Results indicated how stable the N-vinyl Pyrrolidone (NVP) Superpusher SAV301 could be in comparison to the Hydrolyzed Polyacrylamide polymer (HPAM) Flopaam 3630S. Despite the high viscosity results from HPAM Flopaam 3630S due to its high MW, the polymer is overly sensitive to factors like temperature, salinity and concentration. Quite the contrary was for polymer solutions with Superpusher SAV301; constant viscosity over a wide shear rate range which is the

  10. Unstable oscillators based hyperchaotic circuit

    Murali, K.; Tamasevicius, A.; G. Mykolaitis, A.

    1999-01-01

    A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations in the circ...... in the circuit. The performance of the circuit is investigated by means of numerical integration of appropriate differential equations, PSPICE simulations, and hardware experiment.......A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations...

  11. Nuclear data for unstable isotopes

    Sorlin, O.

    1992-01-01

    Nuclear Physics and Astrophysics are both entrusted with the task of understanding nucleosynthesis and energy production in the stars. At high temperatures and densities present in explosive scenarii such as the early universe, cataclysmic binary stars (nova or accretion stars), and supernovae, the nucleosynthesis proceeds throughout unstable nuclei. In order to produce and to study the most exotic isotopes that are not accessible from stable beam - stable (or radioactive) target experiments, it is necessary to develop facilities that utilize Radioactive Nuclear Beams (RNB). The existing methods for producing unstable nuclei will be described in paragraph 2. A review of the major explosive stellar processes will be made through some selected examples using RNB

  12. Total motion generated in the unstable thoracolumbar spine during management of the typical trauma patient: a comparison of methods in a cadaver model.

    Prasarn, Mark L; Zhou, Haitao; Dubose, Dewayne; Rossi, Gianluca Del; Conrad, Bryan P; Horodyski, Marybeth; Rechtine, Glenn R

    2012-05-01

    The proper prehospital and inpatient management of patients with unstable spinal injuries is critical for prevention of secondary neurological compromise. The authors sought to analyze the amount of motion generated in the unstable thoracolumbar spine during various maneuvers and transfers that a trauma patient would typically be subjected to prior to definitive fixation. Five fresh cadavers with surgically created unstable L-1 burst fractures were tested. The amount of angular motion between the T-12 and L-2 vertebral segments was measured using a 3D electromagnetic motion analysis device. A complete sequence of maneuvers and transfers was then performed that a patient would be expected to go through from the time of injury until surgical fixation. These maneuvers and transfers included spine board placement and removal, bed transfers, lateral therapy, and turning the patient prone onto the operating table. During each of these, the authors performed what they believed to be the most commonly used versus the best techniques for preventing undesirable motion at the injury level. When placing a spine board there was more motion in all 3 planes with the log-roll technique, and this difference reached statistical significance for axial rotation (p = 0.018) and lateral bending (p = 0.003). Using logrolling for spine board removal resulted in increased motion again, and this was statistically significant for flexion-extension (p = 0.014). During the bed transfer and lateral therapy, the log-roll technique resulted in more motion in all 3 planes (p ≤ 0.05). When turning the cadavers prone for surgery there was statistically more angular motion in each plane for manually turning the patient versus the Jackson table turn (p ≤ 0.01). The total motion was decreased by almost 50% in each plane when using an alternative to the log-roll techniques during the complete sequence (p ≤ 0.007). Although it is unknown how much motion in the unstable spine is necessary to cause

  13. Rock formation characterization for CO2-EOR and carbon geosequestration; 3D seismic amplitude and coherency anomalies, Wellington Field, Kansas, USA

    Ohl, D.; Raef, A.; Watnef, L.; Bhattacharya, S.

    2011-01-01

    In this paper, we present a workflow for a Mississipian carbonates characterization case-study integrating post-stack seismic attributes, well-logs porosities, and seismic modeling to explore relating changes in small-scale "lithofacies" properties and/or sub-seismic resolution faulting to key amplitude and coherency 3D seismic attributes. The main objective of this study is to put emphasis on reservoir characterization that is both optimized for and subsequently benefiting from pilot tertiary CO2-EOR in preparation for future carbon geosequestration in a depleting reservoir and a deep saline aquifer. The extracted 3D seismic coherency attribute indicated anomalous features that can be interpreted as a lithofacies change or a sub-seismic resolution faulting. A 2D finite difference modeling has been undertaken to understand and potentially build discriminant attributes to map structural and/or lithofacies anomalies of interest especially when embarking upon CO2-EOR and/or carbon sequestration monitoring and management projects. ?? 2011 Society of Exploration Geophysicists.

  14. Heteroclinic cycles between unstable attractors

    Broer, Henk; Efstathiou, Konstantinos; Subramanian, Easwar

    2008-01-01

    We consider networks of pulse coupled linear oscillators with non-zero delay where the coupling between the oscillators is given by the Mirollo–Strogatz function. We prove the existence of heteroclinic cycles between unstable attractors for a network of four oscillators and for an open set of parameter values

  15. Heteroclinic cycles between unstable attractors

    Broer, Henk; Efstathiou, Konstantinos; Subramanian, Easwar

    We consider networks of pulse coupled linear oscillators with non-zero delay where the coupling between the oscillators is given by the Mirollo-Strogatz function. We prove the existence of heteroclinic cycles between unstable attractors for a network of four oscillators and for an open set of

  16. The Fate of Unstable Circumbinary Planets

    Kohler, Susanna

    2016-03-01

    What happens to Tattooine-like planets that are instead in unstable orbits around their binary star system? A new study examines whether such planets will crash into a host star, get ejected from the system, or become captured into orbit around one of their hosts.Orbit Around a DuoAt this point we have unambiguously detected multiple circumbinary planets, raising questions about these planets formation and evolution. Current models suggest that it is unlikely that circumbinary planets would be able to form in the perturbed environment close their host stars. Instead, its thought that the planets formed at a distance and then migrated inwards.One danger such planets face when migrating is encountering ranges of radii where their orbits become unstable. Two scientists at the University of Chicago, Adam Sutherland and Daniel Fabrycky, have studied what happens when circumbinary planets migrate into such a region and develop unstable orbits.Producing Rogue PlanetsTime for planets to either be ejected or collide with one of the two stars, as a function of the planets starting distance (in AU) from the binary barycenter. Colors represent different planetary eccentricities. [Sutherland Fabrycky 2016]Sutherland and Fabrycky used N-body simulations to determine the fates of planets orbiting around a star system consisting of two stars a primary like our Sun and a secondary roughly a tenth of its size that are separated by 1 AU.The authors find that the most common fate for a circumbinary planet with an unstable orbit is ejection from the system; over 80% of unstable planets were ejected. This has interesting implications: if the formation of circumbinary planets is common, this mechanism could be filling the Milky Way with a population of free-floating, rogue planets that no longer are associated with their host star.The next most common outcome for unstable planets is collision with one of their host stars (most often the secondary), resulting inaccretion of the planet

  17. Total motion generated in the unstable cervical spine during management of the typical trauma patient: a comparison of methods in a cadaver model.

    Prasarn, Mark L; Horodyski, MaryBeth; Dubose, Dewayne; Small, John; Del Rossi, Gianluca; Zhou, Haitao; Conrad, Bryan P; Rechtine, Glenn R

    2012-05-15

    Biomechanical cadaveric study. We sought to analyze the amount of motion generated in the unstable cervical spine during various maneuvers and transfers that a trauma patient would typically be subjected to prior to definitive fixation, using 2 different protocols. From the time of injury until the spine is adequately stabilized in the operating room, every step in management of the spine-injured patient can result in secondary injury to the spinal cord. The amount of angular motion between C5 and C6, after a surgically created unstable injury, was measured using an electromagnetic motion analysis device (Polhemus Inc., Colchester, VT). A total sequence of maneuvers and transfers was then performed that a patient would be expected to go through from the time of injury until surgical fixation. This included spine board placement and removal, bed transfers, lateral therapy, and turning the patient prone onto the operating table. During each of these, we performed what has been shown to be the best and commonly used (log-roll) techniques. During bed transfers and the turn prone for surgery, there was statistically more angular motion in each plane for traditional transfer with the spine board and manually turning the patient prone as commonly done (P patient from the field to stabilization in the operating room using the best compared with the most commonly used techniques. As previously reported, using log-roll techniques consistently results in unwanted motion at the injured spinal segment.

  18. EoR Foregrounds: the Faint Extragalactic Radio Sky

    Prandoni, Isabella

    2018-05-01

    A wealth of new data from upgraded and new radio interferometers are rapidly improving and transforming our understanding of the faint extra-galactic radio sky. Indeed the mounting statistics at sub-mJy and μJy flux levels is finally allowing us to get stringent observational constraints on the faint radio population and on the modeling of its various components. In this paper I will provide a brief overview of the latest results in areas that are potentially important for an accurate treatment of extra-galactic foregrounds in experiments designed to probe the Epoch of Reionization.

  19. Fundamentals of carbon dioxide-enhanced oil recovery (CO2-EOR): a supporting document of the assessment methodology for hydrocarbon recovery using CO2-EOR associated with carbon sequestration

    Verma, Mahendra K.

    2015-01-01

    The objective of this report is to provide basic technical information regarding the CO2-EOR process, which is at the core of the assessment methodology, to estimate the technically recoverable oil within the fields of the identified sedimentary basins of the United States. Emphasis is on CO2-EOR because this is currently one technology being considered as an ultimate long-term geologic storage solution for CO2 owing to its economic profitability from incremental oil production offsetting the cost of carbon sequestration.

  20. Exploring the Physics of Unstable Nuclei

    Volya, Alexander

    In this presentation the Continuum Shell Model (CSM) approach is advertised as a powerful theoretical tool for studying physics of unstable nuclei. The approach is illustrated using 17O as an example, which is followed by a brief presentation of the general CSM formalism. The successes of the CSM are highlighted and references are provided throughout the text. As an example, the CSM is applied perturbatively to 20O allowing one to explore the effects of continuum on positions of weakly bound states and low-lying resonances, as well as to discern some effects of threshold discontinuity.

  1. Nuclear Data on Unstable Nuclei for Astrophysics

    Smith, Michael Scott; Meyer, Richard A; Lingerfelt, Eric; Scott, J.P.; Hix, William Raphael; Ma, Zhanwen; Bardayan, Daniel W.; Blackmon, Jeff C.; Guidry, Mike W.; KOZUB, RAYMOND L.; Chae, Kyung YuK.

    2004-01-01

    Recent measurements with radioactive beams at ORNL's Holifield Radioactive Ion Beam Facility (HRIBF) have prompted the evaluation of a number of reactions involving unstable nuclei needed for stellar explosion studies. We discuss these evaluations, as well as the development of a new computational infrastructure to enable the rapid incorporation of the latest nuclear physics results in astrophysics models. This infrastructure includes programs that simplify the generation of reaction rates, manage rate databases, and visualize reaction rates, all hosted at a new website http://www.nucastrodata.org

  2. Exploring the physics of unstable nuclei

    Volya, Alexander

    2015-01-01

    In this presentation the Continuum Shell Model (CSM) approach is advertised as a powerful theoretical tool for studying physics of unstable nuclei. The approach is illustrated using 17 O as an example, which is followed by a brief presentation of the general CSM formalism. The successes of the CSM are highlighted and references are provided throughout the text. As an example, the CSM is applied perturbatively to 20 O allowing one to explore the effects of continuum on positions of weakly bound states and low-lying resonances, as well as to discern some effects of threshold discontinuity. (author)

  3. Quantum electrodynamics with unstable vacuum

    Fradkin, E.S. (P.N. Lebedev Physical Inst., USSR Academy of Sciences, Moscow (USSR)); Gitman, D.M. (Moscow Inst. of Radio Engineering Electronics and Automation (USSR)); Shvartsman, Sh.M. (Tomsk State Pedagogical Inst. (USSR))

    1991-01-01

    Intense external fields destabilize vacuum inducing the creation of particle pairs. In this book the formalism of quantum electrodynamics (QED), using a special perturbation theory with matrix propagators, is systematically analyzed for such systems. The developed approach is, however, general for any quantum field with unstable vacuum. The authors propose solutions for real pair-creating fields. They discuss the general form for the causal function and many other Green's functions, as well as methods for finding them. Analogies to the optical theorem and rules for computing total probabilities are given, as are solutions for non-Abelian theories. (orig.).

  4. Infrared sensitivity of unstable vacua

    Krotov, Dmitry; Polyakov, Alexander M.

    2011-01-01

    We discover that some unstable vacua have long memory. By that we mean that even in the theories containing only massive particles, there are correllators and expectation values which grow with time. We examine the cases of instabilities caused by the constant electric fields, expanding and contracting universes and, most importantly, the global de Sitter space. In the last case the interaction leads to a remarkable UV/IR mixing and to a large back reaction. This gives reasons to believe that the cosmological constant problem could be resolved by the infrared physics.

  5. Faults as Windows to Monitor Gas Seepage: Application to CO2 Sequestration and CO2-EOR

    Ronald W. Klusman

    2018-03-01

    Full Text Available Monitoring of potential gas seepage for CO2 sequestration and CO2-EOR (Enhanced Oil Recovery in geologic storage will involve geophysical and geochemical measurements of parameters at depth and at, or near the surface. The appropriate methods for MVA (Monitoring, Verification, Accounting are needed for both cost and technical effectiveness. This work provides an overview of some of the geochemical methods that have been demonstrated to be effective for an existing CO2-EOR (Rangely, CA, USA and a proposed project at Teapot Dome, WY, USA. Carbon dioxide and CH4 fluxes and shallow soil gas concentrations were measured, followed by nested completions of 10-m deep holes to obtain concentration gradients. The focus at Teapot Dome was the evaluation of faults as pathways for gas seepage in an under-pressured reservoir system. The measurements were supplemented by stable carbon and oxygen isotopic measurements, carbon-14, and limited use of inert gases. The work clearly demonstrates the superiority of CH4 over measurements of CO2 in early detection and quantification of gas seepage. Stable carbon isotopes, carbon-14, and inert gas measurements add to the verification of the deep source. A preliminary accounting at Rangely confirms the importance of CH4 measurements in the MVA application.

  6. Area 2. Use Of Engineered Nanoparticle-Stabilized CO2 Foams To Improve Volumetric Sweep Of CO2 EOR Processes

    DiCarlo, David [Univ. of Texas, Austin, TX (United States); Huh, Chun [Univ. of Texas, Austin, TX (United States); Johnston, Keith P. [Univ. of Texas, Austin, TX (United States)

    2015-01-31

    The goal of this project was to develop a new CO2 injection enhanced oil recovery (CO2-EOR) process using engineered nanoparticles with optimized surface coatings that has better volumetric sweep efficiency and a wider application range than conventional CO2-EOR processes. The main objectives of this project were to (1) identify the characteristics of the optimal nanoparticles that generate extremely stable CO2 foams in situ in reservoir regions without oil; (2) develop a novel method of mobility control using “self-guiding” foams with smart nanoparticles; and (3) extend the applicability of the new method to reservoirs having a wide range of salinity, temperatures, and heterogeneity. Concurrent with our experimental effort to understand the foam generation and transport processes and foam-induced mobility reduction, we also developed mathematical models to explain the underlying processes and mechanisms that govern the fate of nanoparticle-stabilized CO2 foams in porous media and applied these models to (1) simulate the results of foam generation and transport experiments conducted in beadpack and sandstone core systems, (2) analyze CO2 injection data received from a field operator, and (3) aid with the design of a foam injection pilot test. Our simulator is applicable to near-injection well field-scale foam injection problems and accounts for the effects due to layered heterogeneity in permeability field, foam stabilizing agents effects, oil presence, and shear-thinning on the generation and transport of nanoparticle-stabilized C/W foams. This report presents the details of our experimental and numerical modeling work and outlines the highlights of our findings.

  7. Tracer filamentation at an unstable ocean front

    Feng, Yen Chia; Mahadevan, Amala; Thiffeault, Jean-Luc; Yecko, Philip

    2017-11-01

    A front, where two bodies of ocean water with different physical properties meet, can become unstable and lead to a flow with high strain rate and vorticity. Phytoplankton and other oceanic tracers are stirred into filaments by such flow fields, as can often be seen in satellite imagery. The stretching and folding of a tracer by a two-dimensional flow field has been well studied. In the ocean, however, the vertical shear of horizontal velocity is typically two orders of magnitude larger than the horizontal velocity gradient. Theoretical calculations show that vertical shear alters the way in which horizontal strain affects the tracer, resulting in thin, sloping structures in the tracer field. Using a non-hydrostatic ocean model of an unstable ocean front, we simulate tracer filamentation to identify the effect of vertical shear on the deformation of the tracer. In a complementary laboratory experiment, we generate a simple, vertically sheared strain flow and use dye and particle image velocimetry to quantify the filamentary structures in terms of the strain and shear. We identify how vertical shear alters the tracer filaments and infer how the evolution of tracers in the ocean will differ from the idealized two-dimensional paradigm. Support of NSF DMS-1418956 is acknowledged.

  8. Unstable decay and state selection

    McKane, Alan; Tarlie, Martin

    2001-01-01

    The decay of unstable states when several metastable states are available for occupation is investigated using path-integral techniques. Specifically, a method is described that enables the probabilities with which the metastable states are occupied to be calculated by finding optimal paths, and fluctuations about them, in the weak-noise limit. The method is illustrated on a system described by two coupled Langevin equations, which are found in the study of instabilities in fluid dynamics and superconductivity. The problem involves a subtle interplay between nonlinearities and noise, and a naive approximation scheme that does not take this into account is shown to be unsatisfactory. The use of optimal paths is briefly reviewed and then applied to finding the conditional probability of ending up in one of the metastable states, having begun in the unstable state. There are several aspects of the calculation that distinguish it from most others involving optimal paths: (i) the paths do not begin and end on an attractor, and moreover, the final point is to a large extent arbitrary, (ii) the interplay between the fluctuations and the leading-order contribution are at the heart of the method, and (iii) the final result involves quantities that are not exponentially small in the noise strength. This final result, which gives the probability of a particular state being selected in terms of the parameters of the dynamics, is remarkably simple and agrees well with the results of numerical simulations. The method should be applicable to similar problems in a number of other areas, such as state selection in lasers, activationless chemical reactions, and population dynamics in fluctuating environments

  9. CONSTRAINING POLARIZED FOREGROUNDS FOR EoR EXPERIMENTS. I. 2D POWER SPECTRA FROM THE PAPER-32 IMAGING ARRAY

    Kohn, S. A.; Aguirre, J. E.; Moore, D. F. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA (United States); Nunhokee, C. D.; Bernardi, G. [Department of Physics and Electronics, Rhodes University, Grahamstown (South Africa); Pober, J. C. [Department of Physics, Brown University, Providence, RI (United States); Ali, Z. S.; DeBoer, D. R.; Parsons, A. R. [Astronomy Department, University of California, Berkeley, CA (United States); Bradley, R. F. [Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA (United States); Carilli, C. L. [National Radio Astronomy Observatory, Socorro, NM (United States); Gugliucci, N. E. [Saint Anselm College, Manchester, NH (United States); Jacobs, D. C. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Klima, P. [National Radio Astronomy Observatory, Charlottesville, VA (United States); MacMahon, D. H. E. [Radio Astronomy Laboratory, University of California, Berkeley, CA (United States); Manley, J. R.; Walbrugh, W. P. [SKA South Africa, Pinelands (South Africa); Stefan, I. I., E-mail: saulkohn@sas.upenn.edu [Cavendish Laboratory, Cambridge (United Kingdom)

    2016-06-01

    Current generation low-frequency interferometers constructed with the objective of detecting the high-redshift 21 cm background aim to generate power spectra of the brightness temperature contrast of neutral hydrogen in primordial intergalactic medium. Two-dimensional (2D) power spectra (power in Fourier modes parallel and perpendicular to the line of sight) that formed from interferometric visibilities have been shown to delineate a boundary between spectrally smooth foregrounds (known as the wedge ) and spectrally structured 21 cm background emission (the EoR window ). However, polarized foregrounds are known to possess spectral structure due to Faraday rotation, which can leak into the EoR window. In this work we create and analyze 2D power spectra from the PAPER-32 imaging array in Stokes I, Q, U, and V. These allow us to observe and diagnose systematic effects in our calibration at high signal-to-noise within the Fourier space most relevant to EoR experiments. We observe well-defined windows in the Stokes visibilities, with Stokes Q, U, and V power spectra sharing a similar wedge shape to that seen in Stokes I. With modest polarization calibration, we see no evidence that polarization calibration errors move power outside the wedge in any Stokes visibility to the noise levels attained. Deeper integrations will be required to confirm that this behavior persists to the depth required for EoR detection.

  10. Velocity Spectra in the Unstable Planetary Boundary Layer

    Højstrup, Jørgen

    1982-01-01

    Models for velocity spectra of all three components in the lower half of the unstable PBL are presented. The model spectra are written as a sum of two parts, nS(n) = A(fi, z/zi)w*2 + B(f, z/zi)u*02, a mixed layer part with a stability dependence, and a surface layer part without stability...

  11. Quantifying the non-Gaussianity in the EoR 21-cm signal through bispectrum

    Majumdar, Suman; Pritchard, Jonathan R.; Mondal, Rajesh; Watkinson, Catherine A.; Bharadwaj, Somnath; Mellema, Garrelt

    2018-05-01

    The epoch of reionization (EoR) 21-cm signal is expected to be highly non-Gaussian in nature and this non-Gaussianity is also expected to evolve with the progressing state of reionization. Therefore the signal will be correlated between different Fourier modes (k). The power spectrum will not be able capture this correlation in the signal. We use a higher order estimator - the bispectrum - to quantify this evolving non-Gaussianity. We study the bispectrum using an ensemble of simulated 21-cm signal and with a large variety of k triangles. We observe two competing sources driving the non-Gaussianity in the signal: fluctuations in the neutral fraction (x_{H I}) field and fluctuations in the matter density field. We find that the non-Gaussian contribution from these two sources varies, depending on the stage of reionization and on which k modes are being studied. We show that the sign of the bispectrum works as a unique marker to identify which among these two components is driving the non-Gaussianity. We propose that the sign change in the bispectrum, when plotted as a function of triangle configuration cos θ and at a certain stage of the EoR can be used as a confirmative test for the detection of the 21-cm signal. We also propose a new consolidated way to visualize the signal evolution (with evolving \\bar{x}_{H I} or redshift), through the trajectories of the signal in a power spectrum and equilateral bispectrum i.e. P(k) - B(k, k, k) space.

  12. Enhanced Oil Recovery (EOR by Miscible CO2 and Water Flooding of Asphaltenic and Non-Asphaltenic Oils

    Edwin A. Chukwudeme

    2009-09-01

    Full Text Available An EOR study has been performed applying miscible CO2 flooding and compared with that for water flooding. Three different oils are used, reference oil (n-decane, model oil (n-C10, SA, toluene and 0.35 wt % asphaltene and crude oil (10 wt % asphaltene obtained from the Middle East. Stearic acid (SA is added representing a natural surfactant in oil. For the non-asphaltenic oil, miscible CO2 flooding is shown to be more favourable than that by water. However, it is interesting to see that for first years after the start of the injection (< 3 years it is shown that there is almost no difference between the recovered oils by water and CO2, after which (> 3 years oil recovery by gas injection showed a significant increase. This may be due to the enhanced performance at the increased reservoir pressure during the first period. Maximum oil recovery is shown by miscible CO2 flooding of asphaltenic oil at combined temperatures and pressures of 50 °C/90 bar and 70 °C/120 bar (no significant difference between the two cases, about 1% compared to 80 °C/140 bar. This may support the positive influence of the high combined temperatures and pressures for the miscible CO2 flooding; however beyond a certain limit the oil recovery declined due to increased asphaltene deposition. Another interesting finding in this work is that for single phase oil, an almost linear relationship is observed between the pressure drop and the asphaltene deposition regardless of the flowing fluid pressure.

  13. Enhanced oil recovery (EOR) by miscible CO{sub 2} and water flooding of asphaltenic and non-asphaltenic oils

    Chukwudeme, E. A.; Hamouda, A. A. [Department of Petroleum Engineering, University of Stavanger, 4036 Stavanger (Norway)

    2009-07-01

    An EOR study has been performed applying miscible CO{sub 2} flooding and compared with that for water flooding. Three different oils are used, reference oil (n-decane), model oil (n-C10, SA, toluene and 0.35 wt % asphaltene) and crude oil (10 wt % asphaltene) obtained from the Middle East. Stearic acid (SA) is added representing a natural surfactant in oil. For the non-asphaltenic oil, miscible CO{sub 2} flooding is shown to be more favourable than that by water. However, it is interesting to see that for first years after the start of the injection (< 3 years) it is shown that there is almost no difference between the recovered oils by water and CO{sub 2}, after which (> 3 years) oil recovery by gas injection showed a significant increase. This may be due to the enhanced performance at the increased reservoir pressure during the first period. Maximum oil recovery is shown by miscible CO{sub 2} flooding of asphaltenic oil at combined temperatures and pressures of 50 {sup o}C/90 bar and 70 {sup o}C/120 bar (no significant difference between the two cases, about 1%) compared to 80 {sup o}C/140 bar. This may support the positive influence of the high combined temperatures and pressures for the miscible CO{sub 2} flooding; however beyond a certain limit the oil recovery declined due to increased asphaltene deposition. Another interesting finding in this work is that for single phase oil, an almost linear relationship is observed between the pressure drop and the asphaltene deposition regardless of the flowing fluid pressure. (author)

  14. Capture cross sections on unstable nuclei

    Tonchev, A. P.; Escher, J. E.; Scielzo, N.; Bedrossian, P.; Ilieva, R. S.; Humby, P.; Cooper, N.; Goddard, P. M.; Werner, V.; Tornow, W.; Rusev, G.; Kelley, J. H.; Pietralla, N.; Scheck, M.; Savran, D.; Löher, B.; Yates, S. W.; Crider, B. P.; Peters, E. E.; Tsoneva, N.; Goriely, S.

    2017-09-01

    Accurate neutron-capture cross sections on unstable nuclei near the line of beta stability are crucial for understanding the s-process nucleosynthesis. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining the most relevant observables that can constrain Hauser-Feshbach statistical-model calculations of capture cross sections. Specifically, we will consider photon scattering using monoenergetic and 100% linearly polarized photon beams. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes near and far from stability will be discussed.

  15. Unstable Temperature Distribution in Friction Stir Welding

    Sadiq Aziz Hussein

    2014-01-01

    Full Text Available In the friction stir welding process, a nonuniform and high generated temperature is undesirable. Unstable temperature and distribution affect thermal and residual stresses along the welding line, thus necessitating mitigation. This paper presents a simple method to prevent significant temperature difference along the welding line and also to help nullifying some defect types associated with this welding, such as end-hole, initial unwelded line, and deformed areas. In the experimental investigation, a heat and force thermocouple and dynamometer were utilized while couple-field thermomechanical models were used to evaluate temperature and its distribution, plastic strain, and material displacement. The suggested method generated uniform temperature distributions. Measurement results are discussed, showing a good correlation with predictions.

  16. Capture cross sections on unstable nuclei

    Tonchev A.P.

    2017-01-01

    Full Text Available Accurate neutron-capture cross sections on unstable nuclei near the line of beta stability are crucial for understanding the s-process nucleosynthesis. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining the most relevant observables that can constrain Hauser-Feshbach statistical-model calculations of capture cross sections. Specifically, we will consider photon scattering using monoenergetic and 100% linearly polarized photon beams. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes near and far from stability will be discussed.

  17. Electromagnetic Radiation Originating from Unstable Electron Oscillations

    Juul Rasmussen, Jens; Pécseli, Hans

    1975-01-01

    Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function.......Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function....

  18. Rheology of unstable mineral emulsions

    Sokolović Dunja S.

    2013-01-01

    Full Text Available In this paper, the rheology of mineral oils and their unstable water emulsion were investigated. The oil samples were domestic crude oil UA, its fractions UA1, UA4 and blend semi-product UP1, while the concentration of oil in water emulsions was in the range from 1 up to 30%. The results were analyzed based on shear stress. The oil samples UA, UA1 and UP1 are Newtonian fluids, while UA4 is pseudoplastic fluid. The samples UA and UA4 show higher value of shear stress (83.75 Pa, 297 Pa, then other two samples UA1 and UP1 (18.41 Pa, 17.52 Pa. Rheology of investigated oils due to its complex chemical composition should be analyzed as a simultaneous effect of all their components. Therefore, structural composition of the oils was determined, namely content of paraffins, naphthenes, aromatics and asphaltenes. All samples contain paraffins, naphthenes and aromatics but only oils UA and UA4 contain asphaltenes as well. All investigated emulsions except 30% EUA4 are Newtonian fluids. The EUA4 30% emulsion shows pseudoplastic behaviour, and it is the only 30% emulsion among investigated ones that achieves lower shear stress then its oil. The characteristics of oil samples that could have an influence on their properties and their emulsion rheology, were determined. These characteristics are: neutralization number, interfacial tension, dielectric constant, and emulsivity. Oil samples UA and UA4 have significantly higher values of neutralization number, dielectric constants, and emulsivity. The sample UA has the lowest value of interface tension and the greatest emulsivity, indicating that this oil, among all investigated, has the highest preference for building emulsion. This could be the reason why 20% and 30% emulsions of the oil UA achieve the highest shear stress among all investigated emulsions.

  19. Proton scattering from unstable nuclei {sup 20}O, {sup 30}S, {sup 34}Ar: experimental study and models; Diffusion de protons sur les noyaux instables {sup 20}O, {sup 30}S, {sup 34}Ar: etude experimentale et developpement de modeles

    Khan, Elias [Institut de Physique Nucleaire, CNRS - IN2P3, Universite Paris - Sud, 91406 Orsay Cedex (France)

    2000-01-28

    Elastic and inelastic proton scattering from the unstable nuclei {sup 20}O, {sup 30}S and {sup 34}Ar were measured in inverse kinematics at the Grand Accelerateur National d'Ions Lourds. Secondary beams of {sup 20}O at 43 MeV/A, {sup 30}S at 53 MeV/A and {sup 34}Ar at 47 MeV/A impinged on a (CH{sub 2}){sub n} target. Recoiling protons were detected in the silicon strip array MUST. Energies and angular distributions of the first 2{sup +} and 3{sup -} states were measured. A phenomenological analysis yields values of the deformation parameters {beta}{sub 2} and {beta}{sub 3} of 0.55 (6) and 0.35 (5) for {sup 20}O, 0.32 (3) and 0.22 (4) for {sup 30}S, 0.27 (2) and 0.39 (3) for {sup 34}Ar, respectively, and allows the extraction of the ratio of neutron to proton transition matrix elements (M{sub n}/M{sub p})/(N/Z) for 2{sup +} states: 2.35 (37) for {sup 20}O, 0.93 (20) for {sup 30}S and 1.35 (28) for {sup 34}Ar. Therefore the proton rich nuclei {sup 30}S and {sup 34}Ar show a 2{sup +} excitation of isoscalar character whereas the excitation of {sup 20}O is of isovector character. In order to perform a microscopic analysis of the data, we have developed a QRPA model, using three Skyrme interaction: SIII, SG2, SLy4. This model reproduces measured B(EL) values for the oxygen, sulfur and argon isotopic chains, whereas RPA calculations, which do not take pairing into account, underestimate these values. In the case of the QRPA model the energies of the first 2{sup +} state are overestimated by about 1 MeV, but the evolution along the isotopic chains is well reproduced. (M{sub n}/M{sub p})/(N/Z) ratios for the first 2{sup +} state deduced from the microscopic analysis using QRPA are 1.98 for {sup 20}O, 1.05 for {sup 30}S and 1.00 for {sup 34}Ar, in agreement with the conclusions of the phenomenological analysis. However important discrepancies are observed between the two types of analysis for other isotopes, in particular neutron rich argon and sulfur nuclei. (author)

  20. A biomechanical comparison of four fixed-angle dorsal plates in a finite element model of dorsally-unstable radius fracture.

    Knežević, Josip; Kodvanj, Janoš; Čukelj, Fabijan; Pamuković, Frane; Pavić, Arsen

    2017-11-01

    To compare the finite element models of two different composite radius fracture patterns, reduced and stabilised with four different fixed-angle dorsal plates during axial, dorsal and volar loading conditions. Eight different plastic models representing four AO/ASIF type 23-A3 distal radius fractures and four AO/ASIF 23-C2 distal radius fractures were obtained and fixed each with 1 of 4 methods: a standard dorsal non-anatomical fixed angle T-plate (3.5mm Dorsal T-plate, Synthes), anatomical fixed-angle double plates (2.4mm LCP Dorsal Distal Radius, Synthes), anatomical fixed angle T-plate (2.4mm Acu-Loc Dorsal Plate, Acumed) or anatomical variable-angle dorsal T-plate (3.5mm, Dorsal Plate, Zrinski). Composite radius with plate and screws were scanned with a 3D optical scanner and later processed in Abaqus Software to generate the finite element model. All models were axially loaded at 3 points (centrally, volarly and dorsally) with 50 N forces to avoid the appearance of plastic deformations of the models. Total displacements at the end of the bone and the stresses in the bones and plates were determined and compared. Maximal von Mises stress in bone for 3-part fracture models was very similar to that in 2-part fracture models. The biggest difference between models and the largest displacements were seen during volar loading. The stresses in all models were the highest above the fracture gap. The best performance in all parameters tested was with the Zrinski plate and the most modest results were with the Synthes T-plate. There was no significant difference between 2-part (AO/ASIF type 23-A3) and 3-part (AO/ASIF 23-C2) fracture models. Maximal stresses in the plates appeared above the fracture gap; therefore, it is worth considering the development of plates without screw holes above the gap. © 2017 Elsevier Ltd. All rights reserved.

  1. The effect of nonlinearity on unstable zones of Mathieu equation

    2017-02-09

    Feb 9, 2017 ... Abstract. Mathieu equation is a well-known ordinary differential equation in which the excitation term appears as the non-constant coefficient. The mathematical modelling of many dynamic systems leads to Mathieu equation. The determination of the locus of unstable zone is important for the control of ...

  2. Joint inversion of time-lapse VSP data for monitoring CO2 injection at the Farnsworth EOR field in Texas

    Zhang, M.; Gao, K.; Balch, R. S.; Huang, L.

    2016-12-01

    During the Development Phase (Phase III) of the U.S. Southwest Regional Partnership on Carbon Sequestration (SWP), time-lapse 3D vertical seismic profiling (VSP) data were acquired to monitor CO2 injection/migration at the Farnsworth Enhanced Oil Recovery (EOR) field, in partnership with the industrial partner Chaparral Energy. The project is to inject a million tons of carbon dioxide into the target formation, the deep oil-bearing Morrow Formation in the Farnsworth Unit EOR field. Quantitative time-lapse seismic monitoring has the potential to track CO2 movement in geologic carbon storage sites. Los Alamos National Laboratory (LANL) has recently developed new full-waveform inversion methods to jointly invert time-lapse seismic data for changes in elastic and anisotropic parameters in target monitoring regions such as a CO2 reservoir. We apply our new joint inversion methods to time-lapse VSP data acquired at the Farnsworth EOR filed, and present some preliminary results showing geophysical properties changes in the reservoir.

  3. Thin disk laser with unstable resonator and reduced output coupler

    Gavili, Anwar; Shayganmanesh, Mahdi

    2018-05-01

    In this paper, feasibility of using unstable resonator with reduced output coupling in a thin disk laser is studied theoretically. Unstable resonator is modeled by wave-optics using Collins integral and iterative method. An Yb:YAG crystal with 250 micron thickness is considered as a quasi-three level active medium and modeled by solving rate equations of energy levels populations. The amplification of laser beam in the active medium is calculated based on the Beer-Lambert law and Rigrod method. Using generalized beam parameters method, laser beam parameters like, width, divergence, M2 factor, output power as well as near and far-field beam profiles are calculated for unstable resonator. It is demonstrated that for thin disk laser (with single disk) in spite of the low thickness of the disk which leads to low gain factor, it is possible to use unstable resonator (with reduced output coupling) and achieve good output power with appropriate beam quality. Also, the behavior of output power and beam quality versus equivalent Fresnel number is investigated and optimized value of output coupling for maximum output power is achieved.

  4. Evaluation on Influence of Unstable Primary-Energy Price in a Deregulated Electric Power Market—Analysis based on a simulation model approach—

    Maitani, Tatsuyuki; Tezuka, Tetsuo

    The electric power market of Japan has been locally monopolized for a long time. But, like many countries, Japan is moving forward with the deregulation of its electric power industry so that any power generation company could sell electric power in the market. The power price, however, will fluctuate inevitably to balance the power supply and demand. A new appropriate market design is indispensable when introducing new market mechanisms in the electric power market to avoid undesirable results of the market. The first stage of deregulation will be the competition between an existing large-scaled power utility and a new power generation company. In this paper we have investigated the wholesale market with competition of these two power companies based on a simulation model approach. Under the competitive situation the effects of exogenous disturbance may bring serious results and we estimated the influence on the market when the price of fossil fuel rises. The conclusion of this study is that several types of Nash equilibriums have been found in the market: the larger the new power generation company becomes, the higher the electricity price under the Nash equilibriums rises. Because of the difference in their structure of generation capacity, the existing large-scaled power utility gets more profit while the new power generation company loses its profit when the price of fossil fuel rises.

  5. Study of Synthesis Polyethylene glycol oleate Sulfonated as an Anionic Surfactant for Enhanced Oil Recovery (EOR)

    Sampora, Yulianti; Juwono, Ariadne L.; Haryono, Agus; Irawan, Yan

    2017-11-01

    Mechanical Enhanced Oil Recovery (EOR) through chemical injection is using an anionic surfactant to improve the recovery of oil residues, particularly in a reservoir area that has certain characteristics. This case led the authors to conduct research on the synthesis of an anionic surfactant based on oleic acid and polyethylene glycol 400 that could be applied as a chemical injection. In this work, we investigate the sulfonation of Polyethylene glycol oleate (PDO) in a sulfuric acid agent. PDO in this experiment was derived from Indonesian palm oil. Variation of mole reactant and reaction time have been studied. The surfactant has been characterized by measuring the interfacial tension, acid value, ester value, saponification value, iodine value, Fourier Transform Infrared (FTIR), and particle size analyzer. There is a new peak at 1170-1178 cm-1 indicating that S=O bond has formed. PDO sulfonate exhibits good surface activity due to interfacial tension of 0,003 mN/m. Thus, polyethylene glycol oleate sulfonate was successfully synthesized and it could be useful as a novel an anionic surfactant.

  6. A study of unstable rock failures using finite difference and discrete element methods

    Garvey, Ryan J.

    Case histories in mining have long described pillars or faces of rock failing violently with an accompanying rapid ejection of debris and broken material into the working areas of the mine. These unstable failures have resulted in large losses of life and collapses of entire mine panels. Modern mining operations take significant steps to reduce the likelihood of unstable failure, however eliminating their occurrence is difficult in practice. Researchers over several decades have supplemented studies of unstable failures through the application of various numerical methods. The direction of the current research is to extend these methods and to develop improved numerical tools with which to study unstable failures in underground mining layouts. An extensive study is first conducted on the expression of unstable failure in discrete element and finite difference methods. Simulated uniaxial compressive strength tests are run on brittle rock specimens. Stable or unstable loading conditions are applied onto the brittle specimens by a pair of elastic platens with ranging stiffnesses. Determinations of instability are established through stress and strain histories taken for the specimen and the system. Additional numerical tools are then developed for the finite difference method to analyze unstable failure in larger mine models. Instability identifiers are established for assessing the locations and relative magnitudes of unstable failure through measures of rapid dynamic motion. An energy balance is developed which calculates the excess energy released as a result of unstable equilibria in rock systems. These tools are validated through uniaxial and triaxial compressive strength tests and are extended to models of coal pillars and a simplified mining layout. The results of the finite difference simulations reveal that the instability identifiers and excess energy calculations provide a generalized methodology for assessing unstable failures within potentially complex

  7. ${ \\mathcal P }{ \\mathcal T }$-symmetric interpretation of unstable effective potentials

    Bender, Carl M.; Mavromatos, Nick E.; Sarkar, Sarben

    2016-01-01

    The conventional interpretation of the one-loop effective potentials of the Higgs field in the Standard Model and the gravitino condensate in dynamically broken supergravity is that these theories are unstable at large field values. A ${ \\mathcal P }{ \\mathcal T }$-symmetric reinterpretation of these models at a quantum-mechanical level eliminates these instabilities and suggests that these instabilities may also be tamed at the quantum-field-theory level.

  8. Unstable system with Coulomb interaction distorted near the origin

    Kerbikov, B.O.

    1981-01-01

    An unstable system with Coulomb interaction distorted at small distances is considered. The results are applicable to hadronic atoms analysis. A detailed investigation of the model which can be solved exactly is presented. This model contains the separable short-range potential with the Yamaguchi form factor. Closed expressions for the modified effective range function and the Coulomb-modified scattering length ase obtained [ru

  9. Characterization of Unstable Rock Slopes Through Passive Seismic Measurements

    Kleinbrod, U.; Burjanek, J.; Fäh, D.

    2014-12-01

    Catastrophic rock slope failures have high social impact, causing significant damage to infrastructure and many casualties throughout the world each year. Both detection and characterization of rock instabilities are therefore of key importance. An analysis of ambient vibrations of unstable rock slopes might be a new alternative to the already existing methods, e.g. geotechnical displacement measurements. Systematic measurements have been performed recently in Switzerland to study the seismic response of potential rockslides concerning a broad class of slope failure mechanisms and material conditions. Small aperture seismic arrays were deployed at sites of interest for a short period of time (several hours) in order to record ambient vibrations. Each measurement setup included a reference station, which was installed on a stable part close to the instability. Recorded ground motion is highly directional in the unstable parts of the rock slope, and significantly amplified with respect to stable areas. These effects are strongest at certain frequencies, which were identified as eigenfrequencies of the unstable rock mass. In most cases the directions of maximum amplification are perpendicular to open cracks and in good agreement with the deformation directions obtained by geodetic measurements. Such unique signatures might improve our understanding of slope structure and stability. Thus we link observed vibration characteristics with available results of detailed geological characterization. This is supported by numerical modeling of seismic wave propagation in fractured media with complex topography.For example, a potential relation between eigenfrequencies and unstable rock mass volume is investigated.

  10. Unstable magnetic moments in Ce compounds

    Aarts, J.

    1984-01-01

    The problems which are connected with the appearance or disappearance of local moments in metals are well reflected in the magnetic behaviour of Ce intermetallic compounds. This work describes experiments on two Ce compounds which are typical examples of unstable moment systems. The first of these is CeAl 2 which at low temperatures, shows coexistence of antiferromagnetic order and the Kondo effect. Measurements are presented of the magnetization and the susceptibility in different magnetic field and temperature regions. An analysis of these measurements, using a model for the crystal field effects, shows the agreement between the measurements and the calculations to be reasonably good for CeAl 2 , but this agreement becomes worse upon decreasing Ce concentration. A phenomenological description of the observations is given. The second compound reported on is CeCu 2 Si 2 , the first 'heavy-fermion' superconductor to be investigated. The superconducting state is possibly formed by the quasi-particles of a non-magnetic many body singlet state, and not simply by the (sd) conduction electrons. This being a novel phenomenon, a number of experiments were performed to test this picture and to obtain a detailed description of the behaviour of CeCu 2 Si 2 . Measurements of the Meissner volume, confirmed the superconductivity to be intrinsic. (Auth.)

  11. Evaluation and Optimization Study on a Hybrid EOR Technique Named as Chemical-Alternating-Foam Floods

    Xu Xingguang

    2017-01-01

    Full Text Available This work presents a novel Enhanced Oil Recovery (EOR method called Chemical-Alternating-Foam (CAF floods in order to overcome the drawbacks of the conventional foam flooding such as insufficient amount of in-situ foams, severe foam collapse and surfactant retention. The first part of this research focused on the comparison of conventional foam floods and CAF floods both of which had the same amount of gas and chemicals. It showed that: (1 CAF floods possessed the much greater Residual Resistance Factor (RRF at elevated temperature; (2 the accumulative oil recovery of the CAF floods was 10%-15% higher than that of the conventional foam flooding. After 1.8 Pore Volume (PV injection, the oil recovery reached the plateau for both methods; (3 CAF floods yielded the most amount of incremental oil at the 98% water cut (water content in the effluent, while the continuous foam floods achieved the best performance at 60% water cut. The second part of this work determined the optimal foam quality (gas/liquid ratio or the volume percent gas within foam, chemical/foam slug size ratio, cycle number and injection sequence for the CAF floods. It was found that the CAF was endowed with the peak performance if the foam quality, chemical/foam slug size ratio, cycle number was fixed at 80%, 1:1 and 3 respectively with the chemical slug being introduced ahead of the foam slug. Through systematic and thorough research, the proposed hybrid process has been approved to be a viable and effective method significantly strengthening the conventional foam flooding.

  12. Natriuretic peptides in unstable coronary artery disease.

    Jernberg, Tomas; James, Stefan; Lindahl, Bertil; Johnston, Nina; Stridsberg, Mats; Venge, Per; Wallentin, Lars

    2004-09-01

    Patients with unstable coronary artery disease (CAD), i.e., unstable angina or non-ST-elevation myocardial infarction, vary widely in clinical presentation, prognosis and response to treatment. To select appropriate therapy, early risk stratification has become increasingly important. This review focuses on the emerging role of natriuretic peptides in the early assessment of patients with unstable CAD. We conclude that levels of brain natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) are strongly associated to mortality and the risk of future congestive heart failure, and carry important prognostic information independent from previously known risk factors in unstable CAD. There are some data indicating that these markers can also be helpful in the selection of appropriate therapy in these patients but further studies are needed. Before a routine use of BNP or NT-proBNP in unstable CAD can be recommended, the cost-effectiveness of adding these new markers to the currently routine markers and their impact on selection of treatment needs further evaluation. Copyright 2004 Elsevier Ltd

  13. Examination of the creep behaviour of microstructurally unstable ferritic steels

    Williams, K.R.

    1981-01-01

    The inherent microstructural instability of 1/2Cr 1/2Mo 1/4V; 21/4Cr 1Mo and carbon steels creep tested or service exposed at low stresses is demonstrated. Measurements of important dispersion parameters have been made during creep life and have been found to follow normal coarsening kinetics. Using the measured time dependent change of the dispersion parameters, a dislocation source controlled model for recovery creep is used and further developed. The model allows the calculation of the Manson-Haferd plot of log (time to failure) against temperature for unstable steels. In addition, a classification of material stability is proposed, based on the ratio of time to fracture, t(sub f), and time to tertiary creep, tsub(t). This classification enables estimates of remaining creep life to be based either on well established criteria for stable materials or modifications of these criteria for unstable steels. (author)

  14. AMD study of unstable nuclei

    Horiuchi, Hisashi; Dote, Akinobu; Kimura, Masaaki

    2000-01-01

    The formulation of AMD which can describe both mean-field states and clustering states is briefly explained. The results of the application of the AMD model to various isotopes are given. Many problems are discussed which include formation of molecular orbits, new-type of clustering near neutron drip-line, opposite deformation of neutron and proton density distributions, breaking of the neutron magic numbers N=8 and N=20, and so on. The discussions are not necessarily only for the ground states or ground rotational bands but also for the excited states or excited rotational bands in the case of Be isotopes. (author)

  15. AMD study of unstable nuclei

    Horiuchi, Hisashi; Dote, Akinobu; Kimura, Masaaki [Kyoto Univ. (Japan). Dept. of Physics; Kanada-En' yo, Yoshiko [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)

    2000-01-01

    The formulation of AMD which can describe both mean-field states and clustering states is briefly explained. The results of the application of the AMD model to various isotopes are given. Many problems are discussed which include formation of molecular orbits, new-type of clustering near neutron dripline, opposite deformation of neutron and proton density distributions, breaking of the neutron magic numbers N=8 and N=20, and so on. The discussions are not necessarily only for the ground states or ground rotational bands but also for the excited states or excited rotational bands in the case of Be isotopes. (author)

  16. Multiphonon structure of γ-unstable or O(6) nuclei

    Otsuka, T.; Kim, K.H.

    1995-01-01

    The multiphonon structure is shown for the O(6) limit of the Interacting Boson Model. The phonon states are created by the O(6) quadrupole operator with proper symmetrization. All the σ = N states can be described in this scheme in terms of phonon quanta and two-phonon anharmonicity, while the ground state is γ unstable. This structure is carried over into higher-lying σ < N states. (author)

  17. A splitting technique for analytical modelling of two-phase multicomponent flow in porous media

    Pires, A.P.; Bedrikovetsky, P.G.; Shapiro, Alexander

    2006-01-01

    In this paper we discuss one-dimensional models for two-phase Enhanced Oil Recovery (EOR) floods (oil displacement by gases, polymers, carbonized water, hot water, etc.). The main result presented here is the splitting of the EOR mathematical model into thermodynamical and hydrodynamical parts...... formation water for chemical flooding can be calculated from the reduced auxiliary system. Reduction of the number of equations allows the generation of new analytical models for EOR. The analytical model for displacement of oil by a polymer slug with water drive is presented....

  18. Unstable drift eigenmode in slab geometry

    Tsotsonis, S.; Hirose, A.

    1986-01-01

    The unstable Pearlstein-Berk mode of drift waves in plane, sheared slab geometry has later been shown to be stable when electron Landau resonance is rigorously treated. Based on the variational method previously developed the authors have found that in addition to the absolutely stable Pearlstein-Berk mode, there exists an absolutely unstable eigenfunction characterized by ω ≤ ω/sub chemical bonde/, and weak ''radial'' dependence. Also, the growth rate, only weakly depends on the magnetic shear and ion/electron temperature ratio

  19. From stable to unstable anomaly-induced inflation

    Netto, Tibério de Paula; Pelinson, Ana M.; Shapiro, Ilya L.; Starobinsky, Alexei A.

    2016-10-01

    Quantum effects derived through conformal anomaly lead to an inflationary model that can be either stable or unstable. The unstable version requires a large dimensionless coefficient of about 5× {10}^8 in front of the {R}^2 term that results in the inflationary regime in the R+{R}^2 ("Starobinsky") model being a generic intermediate attractor. In this case the non-local terms in the effective action are practically irrelevant, and there is a `graceful exit' to a low curvature matter-like dominated stage driven by high-frequency oscillations of R - scalarons, which later decay to pairs of all particles and antiparticles, with the amount of primordial scalar (density) perturbations required by observations. The stable version is a genuine generic attractor, so there is no exit from it. We discuss a possible transition from stable to unstable phases of inflation. It is shown that this transition is automatic if the sharp cut-off approximation is assumed for quantum corrections in the period of transition. Furthermore, we describe two different quantum mechanisms that may provide a required large {R}^2-term in the transition period.

  20. From stable to unstable anomaly-induced inflation

    Paula Netto, Tiberio de [Universidade Federal de Juiz de Fora, Departamento de Fisica, ICE, Juiz de Fora, MG (Brazil); Pelinson, Ana M. [Universidade Federal de Santa Catarina, Departamento de Fisica, CFM, Bairro da Trindade, Florianopolis, SC (Brazil); Shapiro, Ilya L. [Universidade Federal de Juiz de Fora, Departamento de Fisica, ICE, Juiz de Fora, MG (Brazil); Tomsk State Pedagogical University and Tomsk State University, Tomsk (Russian Federation); Starobinsky, Alexei A. [L.D. Landau Institute for Theoretical Physics RAS, Moscow (Russian Federation); Utrecht University, Department of Physics and Astronomy, Institute for Theoretical Physics, Utrecht (Netherlands)

    2016-10-15

    Quantum effects derived through conformal anomaly lead to an inflationary model that can be either stable or unstable. The unstable version requires a large dimensionless coefficient of about 5 x 10{sup 8} in front of the R{sup 2} term that results in the inflationary regime in the R+R{sup 2} (''Starobinsky'') model being a generic intermediate attractor. In this case the non-local terms in the effective action are practically irrelevant, and there is a 'graceful exit' to a low curvature matter-like dominated stage driven by high-frequency oscillations of R - scalarons, which later decay to pairs of all particles and antiparticles, with the amount of primordial scalar (density) perturbations required by observations. The stable version is a genuine generic attractor, so there is no exit from it. We discuss a possible transition from stable to unstable phases of inflation. It is shown that this transition is automatic if the sharp cut-off approximation is assumed for quantum corrections in the period of transition. Furthermore, we describe two different quantum mechanisms that may provide a required large R{sup 2}-term in the transition period. (orig.)

  1. Optical isotope shifts for unstable samarium isotopes

    Eastham, D.A.; Walker, P.M.; Griffith, J.A.R.; Evans, D.E.; Grant, I.S.; England, J.G.; Fawcett, M.J.

    1984-01-01

    Using a tunable dye laser beam intersecting a thermal atomic beam, optical isotope shifts and hyperfine splittings have been measured for the four unstable samarium isotopes between 144 Sm and 154 Sm, covering the well known transition region from spherical to deformed shapes. (orig.)

  2. Unstable Systems in Relativistic Quantum Field Theory

    Maiani, Luciano

    1998-01-01

    We show how the state of an unstable particle can be defined in terms of stable asymptotic states. This general definition is used to discuss and to solve some old problems connected with the short-time and large-time behaviour of the non-decay amplitude.

  3. Unstable Titan-generated Rayleigh-Taylor Lakes Impact Ice

    Umurhan, O. M.; Korycansky, D. G.; Zahnle, K. J.

    2014-12-01

    The evolution of surface morphology on Titan, Triton, and other worlds is strongly influenced by the interplay of various fluid dynamical processes. Specifically, overturning instabilities can easily arise due to the special circumstances of landform evolution that probably occurred on these worlds. On Titan, large impacts that formed basins like Menrva crater (and possibly Hotei Regio) would have generated impact-melt ice lakes unstably arranged over less dense ice. Cantaloupe terrains, for example as seen on Triton, may be the result of condensation of volatiles (methane, nitrogen) leading to unstably stratified layers of different compositions and densities. In each of these cases, Rayleigh-Taylor instabilities leading to large scale diapirism may be at play. In addition to the dynamics of these instabilities, other physical effects (e.g. heat diffusion, freezing/melting, porosity, temperature dependent viscosity) likely play an important role in the evolution of these features. In this ongoing study, we examine the properties of unstably stratified fluids in which the lower less-dense ice has a temperature dependent viscosity. Surprisingly, we find that there exists an optimal disturbance length scale corresponding to the fastest growth of the Rayleigh-Taylor instability. For unstably stratified layers of water (low viscosity heavy liquid lying above an ice whose viscosity increases with depth) the fastest growing mode corresponds to 40-60 km scales with overturn times of approximately 100 days. We present a detailed numerical stability analysis in a corresponding Boussinessq model (in the creeping flow limit) incorporating thermal conduction and latent heat release and we examine the stability properties surveying a variety of parameters. We have also developed a two-dimensional numerical code (a hybrid spectral/compact-differencing scheme) to model the evolution of such systems for which we shall present preliminary numerical results depicting the outcome of

  4. Unstable volatility functions: the break preserving local linear estimator

    Casas, Isabel; Gijbels, Irene

    The objective of this paper is to introduce the break preserving local linear (BPLL) estimator for the estimation of unstable volatility functions. Breaks in the structure of the conditional mean and/or the volatility functions are common in Finance. Markov switching models (Hamilton, 1989......) and threshold models (Lin and Terasvirta, 1994) are amongst the most popular models to describe the behaviour of data with structural breaks. The local linear (LL) estimator is not consistent at points where the volatility function has a break and it may even report negative values for finite samples...

  5. Output Error Method for Tiltrotor Unstable in Hover

    Lichota Piotr

    2017-03-01

    Full Text Available This article investigates unstable tiltrotor in hover system identification from flight test data. The aircraft dynamics was described by a linear model defined in Body-Fixed-Coordinate System. Output Error Method was selected in order to obtain stability and control derivatives in lateral motion. For estimating model parameters both time and frequency domain formulations were applied. To improve the system identification performed in the time domain, a stabilization matrix was included for evaluating the states. In the end, estimates obtained from various Output Error Method formulations were compared in terms of parameters accuracy and time histories. Evaluations were performed in MATLAB R2009b environment.

  6. Orbit dynamics for unstable linear motion

    Parzen, G.

    1997-01-01

    A treatment is given of the orbit dynamics for linear unstable motion that allows for the zeros in the beta function and makes no assumptions about the realness of the betatron and phase functions. The phase shift per turn is shown to be related to the beta function and the number of zeros the beta function goes through per turn. The solutions of the equations of motion are found in terms of the beta function

  7. Orbit dynamics for unstable linear motion

    Parzen, G.

    1996-04-01

    A treatment is given of the orbit dynamics for linear unstable motion that allows for the zeros in the beta function and makes no assumption about the realness of the betatron and phase functions. The phase shift per turn is shown to be related to the beta function and the number of zeros the beta function goes through per turn. The solutions of the equations of motion are found in terms of the beta function

  8. Unstable Resonator Retrofitted Handheld Laser Designator

    1978-06-01

    retrofitted with a negative-branch unstable resona- tor laser and hybrid pump cavity in place of the conventional plane-mirror/ porro prism resonator and...directed by prism B to an expanding telescope, shared with the viewing system of the designator. The actual, unfolded resonator length is approxi...was performed based on using a plane- parallel cavity consisting of a 47% reflectivity output coupler, porro - prism reflector, and the same LiNb03

  9. Monitoring Unstable Glaciers with Seismic Noise Interferometry

    Preiswerk, L. E.; Walter, F.

    2016-12-01

    Gravity-driven glacier instabilities are a threat to human infrastructure in alpine terrain, and this hazard is likely to increase with future changes in climate. Seismometers have been used previously on hazardous glaciers to monitor the natural englacial seismicity. In some situations, an increase in "icequake" activity may indicate fracture growth and thus an imminent major break-off. However, without independent constraints on unstable volumes, such mere event counting is of little use. A promising new approach to monitor unstable masses in Alpine terrain is coda wave interferometry of ambient noise. While already established in the solid earth, application to glaciers is not straightforward, because the lack of inhomogeneities typically suppresses seismic coda waves in glacier ice. Only glaciers with pervasive crevasses provide enough scattering to generate long codas. This is requirement is likely met for highly dynamic unstable glaciers. Here, we report preliminary results from a temporary 5-station on-ice array of seismometers (corner frequencies: 1 Hz, array aperture: 500m) on Bisgletscher (Switzerland). The seismometers were deployed in shallow boreholes, directly above the unstable tongue of the glacier. In the frequency band 4-12 Hz, we find stable noise cross-correlations, which in principle allows monitoring on a subdaily scale. The origin and the source processes of the ambient noise in these frequencies are however uncertain. As a first step, we evaluate the stability of the sources in order to separate effects of changing source parameters from changes of englacial properties. Since icequakes occurring every few seconds may dominate the noise field, we compare their temporal and spatial occurrences with the cross-correlation functions (stability over time, the asymmetry between causal and acausal parts of the cross-correlation functions) as well as with results from beamforming to assess the influence of these transient events on the noise field.

  10. Unstable mass outflow from a binary system

    Nariai, K [Tokyo Univ., Mitaka (Japan). Tokyo Astronomical Observatory; Sugimoto, D

    1976-12-01

    A contact binary system which fills the outer Lagrangian lobe is unstable against the mass loss from the second Lagrangian point. The effect of the mass loss on the remaining system is studied for several typical cases. It is shown that the separation between the components at the periastron decreases with a high rate in most cases; therefore, the system continues to lose mass once gas begins to flow out from the second Lagrangian point.

  11. Unstable fracture of nuclear pressure vessel

    Urata, Kazuyoshi

    1978-01-01

    Unstable fracture of nuclear pressure vessel shell for light water reactors up to 1,000 MWe class is discussed in accordance with ASME Code Sec. XI. The depth of surface crack required to protect against the unstable fracture is calculated on the basis of reactor operating conditions including loss of coolant accidents. Calculated surface crack depth a is equal to tαexp(2.19(a/l)) where l is crack length and t is weld thickness. α is crack depth required to protect against the unstable fracture in terms of the ratio of crack deth to weld thickness for surface crack have infinite length. Using this α, the safety factor included for allowable defect described in Sec. XI and the effects of thickness is discussed. It is derived that allowable defect described in Sec. XI include the safety factor of two on the crack depth for crack initiation at postulated accident and the safety factor of ten for crack depth calculated from point of view of crack arrest at normal conditions. (auth.)

  12. Signatures of unstable semiclassical trajectories in tunneling

    Levkov, D G; Panin, A G; Sibiryakov, S M

    2009-01-01

    It was found recently that processes of multidimensional tunneling are generally described at high energies by unstable semiclassical trajectories. We study two observational signatures related to the instability of trajectories. First, we find an additional power-law dependence of the tunneling probability on the semiclassical parameter as compared to the standard case of potential tunneling. The second signature is a substantial widening of the probability distribution over final-state quantum numbers. These effects are studied using a modified semiclassical technique which incorporates stabilization of the tunneling trajectories. The technique is derived from first principles. We obtain expressions for the inclusive and exclusive tunneling probabilities in the case of unstable semiclassical trajectories. We also investigate the 'phase transition' between the cases of stable and unstable trajectories across certain 'critical' values of energy. Finally, we derive the relation between the semiclassical probabilities of tunneling from the low-lying and highly excited initial states. This puts on firm ground a conjecture made previously in the semiclassical description of collision-induced tunneling in field theory

  13. PIROLISIS LIGNIN DARI LIMBAH INDUSTRI KELAPA SAWIT UNTUK PENGEMBANGAN SURFAKTAN DALAM PROSES ENHANCE OIL RECOVERY (EOR (Pyrolysis of Lignin From Waste of Palm Oil Industries for The Development of Surfactants for Enhance Oil Recovery (EOR

    Suryo Purwono

    2001-12-01

    Full Text Available ABSTRAK Pirolisis dari lignin yang berasal dari limbah industri kelapa sawit dapat menghasilkan alkohol dan derivatif lainnyd yang dapat digunakan sehagai surfaktan. Prosedur penelitian proses pirolisis ini odalah sebagai berikut: I serabut atau tandan sisa pengolahon kelapa sawit yang sudah dikeringkan dimasukkan kedalam reaktor dengan berat tertentu dan dipanaskan sampai suhu yang diinginkan, 2 produk pirolisis yang keluar dari reoktor kemudian didinginkan sampoi mencapai suhu kamor, 3 hasil cair ditampung didalam gelas ukur dan hasil gasnya ditampung di suatu botol tertentu. Suhu paling baik yang dicapai adalah 4A0 "C untuk lignin yong berasal dari serabut dan 350'C untuk lignin yang berasal dari tandan kelapa sawit. Surfaktan yang dihasilkan sekitar j4 sampai 38% dari produk pirolisis. Pada penelitian ini kecepatan reaksi dianggap order satu. Hasil penelitian menunjukkan bahwa surfakton yang dihasilkan dapat membentuk emulsi dengan minyak menta.h. Hal ini menunjukkon bahwa surfaktan yang dihasilkan dapat digunakan sebagai bahan untuk proses EOR.   ABSTRACT Pyrolysis of lignin from waste of palm oil industries produces alcohol and its derivatives which can be sulfonated to become surfactant. The experimental procedures for the pyrolysis process were as follows: 1 dried palm oil husks at a certain weight were put into the pyrolysis reactor and heated up to a certain temperafure; 2 the product leaving the reactor was cooled down to room temperature; and 3 the liquid product was collected in a flask while the gas product was put into a big bottle. The best temperature obtained for producing liquid product was 400 oC for lignin from palm oil fruit fibers and 350 oC for lignin from palm oil fruit stems. The surfactant developed was in the range between 34 and 38% from the pyrolysis product. In this experiment, the reaction rate was assumed to be in first order. The result showed that the surfactant obtained from the experiment could form emulsion

  14. Porter-Thomas distribution in unstable many-body systems

    Volya, Alexander

    2011-01-01

    We use the continuum shell model approach to explore the resonance width distribution in unstable many-body systems. The single-particle nature of a decay, the few-body character of the interaction Hamiltonian, and the collectivity that emerges in nonstationary systems due to the coupling to the continuum of reaction states are discussed. Correlations between the structures of the parent and daughter nuclear systems in the common Fock space are found to result in deviations of decay width statistics from the Porter-Thomas distribution.

  15. Crisis-induced unstable dimension variability in a dynamical system

    Kubo, Geraldo T.; Viana, Ricardo L.; Lopes, Sergio R.; Grebogi, Celso

    2008-01-01

    Unstable dimension variability is an extreme form of non-hyperbolic behavior in chaotic systems whose attractors have periodic orbits with a different number of unstable directions. We propose a new mechanism for the onset of unstable dimension variability based on an interior crisis, or a collision between a chaotic attractor and an unstable periodic orbit. We give a physical example by considering a high-dimensional dissipative physical system driven by impulsive periodic forcing

  16. The fate of unstable gauge flux compactifications

    Burgess, C P [McMaster Univ., Hamilton, ON (Canada). Dept. of Physics and Astronomy; [Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada); Parameswaran, S L [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Zavala, I [Bonn Univ. (Germany). Bethe Center for Theoretical Physics and Physikalisches Inst.

    2008-12-15

    Fluxes are widely used to stabilise extra dimensions, but the supporting monopolelike configurations are often unstable, particularly if they arise as gauge flux within a non-abelian gauge sector. We here seek the endpoint geometries to which this instability leads, focussing on the simplest concrete examples: sphere-monopole compactifications in six dimensions. Without gravity most monopoles in non-abelian gauge groups are unstable, decaying into the unique stable monopole in the same topological class. We show that the same is true in Einstein-YM systems, with the new twist that the decay leads to a shrinkage in the size of the extra dimensions and curves the non-compact directions: in D dimensions a Mink{sub D-2} x S{sub 2} geometry supported by an unstable monopole relaxes to AdS{sub D-2} x S{sub 2}, with the endpoint sphere smaller than the initial one. For supergravity the situation is more complicated because the dilaton obstructs such a simple evolution. The endpoint instead acquires a dilaton gradient, thereby breaking some of the spacetime symmetries. For 6D supergravity we argue that it is the 4D symmetries that break, and examine several candidates for the endpoint geometry. By using the trick of dimensional oxidation it is possible to recast the supergravity system as a higher-dimensional Einstein-YM monopole, allowing understanding of this system to guide us to the corresponding endpoint. The result is a Kasner-like geometry conformal to Mink{sub 4} times S{sub 2}, with nontrivial conformal factor and dilaton breaking the maximal 4D symmetry and generating a singularity. Yet the resulting configuration has a lower potential energy than did the initial one, and is perturbatively stable, making it a sensible candidate endpoint for the evolution. (orig.)

  17. The fate of unstable gauge flux compactifications

    Burgess, C.P.; Parameswaran, S.L.; Zavala, I.

    2008-12-01

    Fluxes are widely used to stabilise extra dimensions, but the supporting monopolelike configurations are often unstable, particularly if they arise as gauge flux within a non-abelian gauge sector. We here seek the endpoint geometries to which this instability leads, focussing on the simplest concrete examples: sphere-monopole compactifications in six dimensions. Without gravity most monopoles in non-abelian gauge groups are unstable, decaying into the unique stable monopole in the same topological class. We show that the same is true in Einstein-YM systems, with the new twist that the decay leads to a shrinkage in the size of the extra dimensions and curves the non-compact directions: in D dimensions a Mink D-2 x S 2 geometry supported by an unstable monopole relaxes to AdS D-2 x S 2 , with the endpoint sphere smaller than the initial one. For supergravity the situation is more complicated because the dilaton obstructs such a simple evolution. The endpoint instead acquires a dilaton gradient, thereby breaking some of the spacetime symmetries. For 6D supergravity we argue that it is the 4D symmetries that break, and examine several candidates for the endpoint geometry. By using the trick of dimensional oxidation it is possible to recast the supergravity system as a higher-dimensional Einstein-YM monopole, allowing understanding of this system to guide us to the corresponding endpoint. The result is a Kasner-like geometry conformal to Mink 4 times S 2 , with nontrivial conformal factor and dilaton breaking the maximal 4D symmetry and generating a singularity. Yet the resulting configuration has a lower potential energy than did the initial one, and is perturbatively stable, making it a sensible candidate endpoint for the evolution. (orig.)

  18. Unstable quantum states and rigged Hilbert spaces

    Gorini, V.; Parravicini, G.

    1978-10-01

    Rigged Hilbert space techniques are applied to the quantum mechanical treatment of unstable states in nonrelativistic scattering theory. A method is discussed which is based on representations of decay amplitudes in terms of expansions over complete sets of generalized eigenvectors of the interacting Hamiltonian, corresponding to complex eigenvalues. These expansions contain both a discrete and a continuum contribution. The former corresponds to eigenvalues located at the second sheet poles of the S matrix, and yields the exponential terms in the survival amplitude. The latter arises from generalized eigenvectors associated to complex eigenvalues on background contours in the complex plane, and gives the corrections to the exponential law. 27 references

  19. Unstable dynamics, nonequilibrium phases, and criticality in networked excitable media

    Franciscis, S. de; Torres, J. J.; Marro, J.

    2010-01-01

    Excitable systems are of great theoretical and practical interest in mathematics, physics, chemistry, and biology. Here, we numerically study models of excitable media, namely, networks whose nodes may occasionally be dormant and the connection weights are allowed to vary with the system activity on a short-time scale, which is a convenient and realistic representation. The resulting global activity is quite sensitive to stimuli and eventually becomes unstable also in the absence of any stimuli. Outstanding consequences of such unstable dynamics are the spontaneous occurrence of various nonequilibrium phases--including associative-memory phases and one in which the global activity wanders irregularly, e.g., chaotically among all or part of the dynamic attractors--and 1/f noise as the system is driven into the phase region corresponding to the most irregular behavior. A net result is resilience which results in an efficient search in the model attractor space that can explain the origin of some observed behavior in neural, genetic, and ill-condensed matter systems. By extensive computer simulation we also address a previously conjectured relation between observed power-law distributions and the possible occurrence of a ''critical state'' during functionality of, e.g., cortical networks, and describe the precise nature of such criticality in the model which may serve to guide future experiments.

  20. CT of hemodynamically unstable abdominal trauma

    Petridis, A.; Pilavaki, M.; Vafiadis, E.; Palladas, P.; Finitsis, S.; Drevelegas, A.

    1999-01-01

    This article is an appraisal of the use of CT in the management of patients with unstable abdominal trauma. We examined 41 patients with abdominal trauma using noncontrast dynamic CT. In 17 patients a postcontrast dynamic CT was also carried out. On CT, 25 patients had hemoperitoneum. Thirteen patients had splenic, 12 hepatic, 6 pancreatic, 8 bowel and mesenteric, 12 renal and 2 vascular injuries. Seven patients had retroperitoneal and 2 patients adrenal hematomas. All but five lesions (three renal, one pancreatic, and one splenic) were hypodense when CT was performed earlier than 8 h following the injury. Postcontrast studies (n = 17), revealed 4 splenic, 3 hepatic, 1 pancreatic, 3 renal, and 2 bowel and mesenteric injuries beyond what was found on noncontrast CT. Surgical confirmation (n = 21) was obtained in 81.81 % of splenic, 66.66 % of hepatic, 83.33 % of pancreatic, 100 % of renal, 100 % of retroperitoneal, and 85.71 % of bowel and mesenteric injuries. The majority of false diagnoses was obtained with noncontrast studies. Computed tomography is a remarkable method for evaluation and management of patients with hemodynamically unstable abdominal trauma, but only if it is revealed in the emergency room. Contrast injection, when it could be done, revealed lesions that were not suspected on initial plain scans. (orig.)

  1. CT of hemodynamically unstable abdominal trauma

    Petridis, A.; Pilavaki, M.; Vafiadis, E.; Palladas, P.; Finitsis, S.; Drevelegas, A. [Department of Radiology, General Hospital ``G. Papanikolaou,`` Thessaloniki (Greece)

    1999-03-01

    This article is an appraisal of the use of CT in the management of patients with unstable abdominal trauma. We examined 41 patients with abdominal trauma using noncontrast dynamic CT. In 17 patients a postcontrast dynamic CT was also carried out. On CT, 25 patients had hemoperitoneum. Thirteen patients had splenic, 12 hepatic, 6 pancreatic, 8 bowel and mesenteric, 12 renal and 2 vascular injuries. Seven patients had retroperitoneal and 2 patients adrenal hematomas. All but five lesions (three renal, one pancreatic, and one splenic) were hypodense when CT was performed earlier than 8 h following the injury. Postcontrast studies (n = 17), revealed 4 splenic, 3 hepatic, 1 pancreatic, 3 renal, and 2 bowel and mesenteric injuries beyond what was found on noncontrast CT. Surgical confirmation (n = 21) was obtained in 81.81 % of splenic, 66.66 % of hepatic, 83.33 % of pancreatic, 100 % of renal, 100 % of retroperitoneal, and 85.71 % of bowel and mesenteric injuries. The majority of false diagnoses was obtained with noncontrast studies. Computed tomography is a remarkable method for evaluation and management of patients with hemodynamically unstable abdominal trauma, but only if it is revealed in the emergency room. Contrast injection, when it could be done, revealed lesions that were not suspected on initial plain scans. (orig.) With 6 figs., 5 tabs., 20 refs.

  2. Dynamics and statistics of unstable quantum states

    Sokolov, V.V.; Zelevinsky, V.G.

    1989-01-01

    The statistical theory of spectra formulated in terms of random matrices is extended to unstable states. The energies and widths of these states are treated as real and imaginary parts of complex eigenvalues for an effective non-hermitian hamiltonian. Eigenvalue statistics are investigated under simple assumptions. If the coupling through common decay channels is weak we obtain a Wigner distribution for the level spacings and a Porter-Thomas one for the widths, with the only exception for spacings less than widths where level repulsion fades out. Meanwhile in the complex energy plane the repulsion of eigenvalues is quadratic in accordance with the T-noninvariant character of decaying systems. In the opposite case of strong coupling with the continuum, k short-lived states are formed (k is the number of open decay channels). These states accumulate almost the whole total width, the rest of the states becoming long-lived. Such a perestroika corresponds to separation of direct processes (a nuclear analogue of Dicke coherent superradiance). At small channel number, Ericson fluctuations of the cross sections are found to be suppressed. The one-channel case is considered in detail. The joint distribution of energies and widths is obtained. The average cross sections and density of unstable states are calculated. (orig.)

  3. Thallium-201 scintigraphy in unstable angina pectoris

    Wackers, F.J.T.; Lie, K.I.; Liem, K.L.; Sokole, E.B.; Samson, G.; Van Der Schoot, J.B.; Durrer, D.

    1978-01-01

    Thallium-201 scintigraphy was performed during the pain free period in 98 patients with unstable angina. Scintiscans were positive in 39 patients, questionable in 27 patients and normal in 32 patients. Eighty-one patients responded favorably to treatment (group I). Seventeen patients had complicated courses (group II) and despite maximal treatment with propranolol either developed infarction (six patients) or continued to have angina necessitating coronary surgery (11 patients). In group I during the pain free period 26 of 81 patients had positive thallium-201 scans, whereas 20 patients had an abnormal ECG at that time; during angina 18 patients had transient ECG changes. In group II during the pain free period 13 of 17 patients had positive scans, whereas two patients had abnormal ECG at that time; during angina 12 patients showed transient ECG changes. The sensitivity to recognize group II was 76% for thallium-201 scintigraphy, 11% for ECG during the pain free period; 70% for ECG during angina; 94% for the combination of either positive scans or abnormal ECG. Thus, positive thallium-201 scans occur in patients with unstable angina, positive scans can be obtained during the pain free period, thallium-201 scans are more frequently positive in patients with complicated course

  4. Relativistic mean field theory for unstable nuclei

    Toki, Hiroshi

    2000-01-01

    We discuss the properties of unstable nuclei in the framework of the relativistic mean field (RMF) theory. We take the RMF theory as a phenomenological theory with several parameters, whose form is constrained by the successful microscopic theory (RBHF), and whose values are extracted from the experimental values of unstable nuclei. We find the outcome with the newly obtained parameter sets (TM1 and TMA) is promising in comparison with various experimental data. We calculate systematically the ground state properties of even-even nuclei up to the drip lines; about 2000 nuclei. We find that the neutron magic shells (N=82, 128) at the standard magic numbers stay at the same numbers even far from the stability line and hence provide the feature of the r-process nuclei. However, many proton magic numbers disappear at the neutron numbers far away from the magic numbers due to the deformations. We discuss how to describe giant resonances for the case of the non-linear coupling terms for the sigma and omega mesons in the relativistic RPA. We mention also the importance of the relativistic effect on the spin observables as the Gamow-Teller strength and the longitudinal and transverse spin responses. (author)

  5. Effect of Teriparatide on Unstable Pertrochanteric Fractures

    Tsan-Wen Huang

    2015-01-01

    Full Text Available We retrospectively analyzed the radiographic and clinical outcomes of unstable pertrochanteric fractures (AO/OTA 31-A2 in 44 patients who underwent dynamic hip screw (DHS fixation and compared the results with 29 patients who received teriparatide in addition to DHS fixation. A significantly shorter time for fracture healing was recorded in the teriparatide-treated group than in the control group. Rates of lag screw sliding, femoral shortening, and varus collapse were all significantly reduced in the teriparatide-treated group. There were no significant differences with regard to superficial wound infection, pneumonia, urinary tract infection, mortality, malunion, and cutting of the lag screw. The mean overall mobility scores were significantly better in the teriparatide-treated group at 3 and 6 months (P<0.001 and P<0.001, resp. but not at 12 months or the last follow-up. The pain scores were also significantly better in the teriparatide-treated group at 3 and 6 months (P=0.040 and P=0.041, resp. but not at 12 months or the last follow-up. Teriparatide improves radiographic outcomes and yields better clinical outcomes at 3 and 6 months postoperatively. The improvement in union time may be important for elderly populations with unstable pertrochanteric fractures to enable them to return to daily activities and reduce morbidity and mortality.

  6. Management of acute unstable acromioclavicular joint injuries.

    Cisneros, Luis Natera; Reiriz, Juan Sarasquete

    2016-12-01

    Surgical management of acute unstable acromioclavicular joint injuries should be focused on realigning the torn ends of the ligaments to allow for healing potential. The most widely utilized treatment methods incorporate the use of metal hardware, which can alter the biomechanics of the acromioclavicular joint. This leads to a second surgical procedure for hardware removal once the ligaments have healed. Patients with unstable acromioclavicular joint injuries managed with arthroscopy-assisted procedures have shown good and excellent clinical outcomes, without the need for a second operation. These procedures incorporate a coracoclavicular suspension device aimed to function as an internal brace, narrowing the coracoclavicular space thus allowing for healing of the torn coracoclavicular ligaments. The lesser morbidity of a minimally invasive approach and the possibility to diagnose and treat concomitant intraarticular injuries; no obligatory implant removal, and the possibility of having a straight visualization of the inferior aspect of the base of the coracoid (convenient when placing coracoclavicular fixation systems) are the main advantages of the arthroscopic approach over classic open procedures. This article consists on a narrative review of the literature in regard to the management of acute acromioclavicular joint instability.

  7. Accelerator complex for unstable beams at INS

    Tomizawa, M.; Arai, S.; Doi, M.; Katayama, T.; Niki, K.; Tokuda, N.; Yoshizawa, M.

    1992-11-01

    The construction of the prototype facility of the Exotic arena in the Japan Hadron Project (JHP) is started in 1992 at the Institute for Nuclear Study (INS), University of Tokyo. The purpose of this facility is to study the various technical problems of the Exotic arena, and to perform the experiment on nuclear and astrophysics with unstable nuclear beam. The unstable nuclei produced by bombarding a thick target with 40 MeV proton beam from the existing SF cyclotron are ionized in the ion sources, mass-analyzed by an ISOL, and transported to the accelerator complex. The accelerator complex consists of a split coaxial RFQ and an interdigital H type linac. The construction of accelerator will be completed in fiscal year 1994. The development of the SCRFQ and the IH linac which is suitable to the post-accelerator of the SCRFQ are reported. Charge stripper and the beam matching between the SCRFQ and the IH linac are explained. A buncher is necessary for the matching of longitudinal phase space between the SCRFQ and the IH linac. (K.I.)

  8. Case Studies of the ROZ CO2 Flood and the Combined ROZ/MPZ CO2 Flood at the Goldsmith Landreth Unit, Ector County, Texas. Using ''Next Generation'' CO2 EOR Technologies to Optimize the Residual Oil Zone CO2 Flood

    Trentham, Robert C. [Univ. of Texas, Midland, TX (United States); Melzer, L. Stephen [Univ. of Texas, Midland, TX (United States); Kuuskraa, Vello [Advanced Resources International, Inc., Arlington, VA (United States); Koperna, George [Advanced Resources International, Inc., Arlington, VA (United States)

    2015-06-30

    The technology for CO2 Enhanced Oil Recovery (CO2 EOR) has significantly advanced since the earliest floods were implemented in the 1970s. At least for the Permian Basin region of the U.S., the oil recovery has been now been extended into residual oil zones (ROZs) where the mobile fluid phase is water and immobile phase is oil. But the nature of the formation and fluids within the ROZs has brought some challenges that were not present when flooding the MPZs. The Goldsmith-Landreth project in the Permian Basin was intended to first identify the most pressing issues of the ROZs floods and, secondly, begin to address them with new techniques designed to optimize a flood that commingled the MPZ and the ROZ. The early phase of the research conducted considerable reservoir and fluid characterization work and identified both technical and commercial challenges of producing the enormous quantities of water when flooding the ROZs. It also noted the differing water compositions in the ROZ as compared to the overlying MPZs. A new CO2 gas lift system using a capillary string was successfully applied during the project which conveyed the CO2 to the deeper and differing ROZ reservoir conditions at Goldsmith and added a second capillary string that facilitated applying scale inhibitors to mitigate the scaling tendencies of the mixing ROZ and MPZ formation waters. The project also undertook a reservoir modeling effort, using the acquired reservoir characterization data, to history match both the primary and water flood phases of the MPZ and to establish the initial conditions for a modeling effort to forecast response of the ROZ to CO2 EOR. With the advantage of many profile logs acquired from the operator, some concentration on the original pattern area for the ROZ pilot was accomplished to attempt to perfect the history match for that area. Several optional scenarios for producing the ROZ were simulated seeking to find the

  9. A boundary integral approach to unstable solidification

    Strain, J.

    1989-01-01

    We consider the supercooled Stefan problem with a general anisotropic curvature- and velocity-dependent boundary condition on the moving interface. We present numerical methods, based on an integral equation formulation and including a new algorithm for moving curves with curvature-dependent velocity. These methods compute a periodic interface with O(Δt) accuracy, where Δt is the time step. Previous work has been limited to short time spans and achieved slightly less than O(Δt 1/2 ) accuracy. Accurate numerical results are seen to agree with the predictions of linear stability theory. This agreement has eluded previous authors, because their numerical methods suffered from grid effects and their linear stability theory was incorrect. We study the long-time evolution of an unstable interface. Our computations exhibit the beginnings of a sidebranching instability when the boundary condition includes anisotropy and tip-splitting in the isotropic case. copyright 1989 Academic Press, Inc

  10. Expansion of Michigan EOR Operations Using Advanced Amine Technology at a 600 MW Project Wolverine Carbon Capture and Storage Project

    H Hoffman; Y kishinevsky; S. Wu; R. Pardini; E. Tripp; D. Barnes

    2010-06-16

    Wolverine Power Supply Cooperative Inc, a member owned cooperative utility based in Cadillac Michigan, proposes to demonstrate the capture, beneficial utilization and storage of CO{sub 2} in the expansion of existing Enhanced Oil Recovery operations. This project is being proposed in response to the US Department of Energy Solicitation DE-FOA-0000015 Section III D, 'Large Scale Industrial CCS projects from Industrial Sources' Technology Area 1. The project will remove 1,000 metric tons per day of CO{sub 2} from the Wolverine Clean Energy Venture 600 MW CFB power plant owned and operated by WPC. CO{sub 2} from the flue gas will be captured using Hitachi's CO{sub 2} capture system and advanced amine technology. The capture system with the advanced amine-based solvent supplied by Hitachi is expected to significantly reduce the cost and energy requirements of CO{sub 2} capture compared to current technologies. The captured CO{sub 2} will be compressed and transported for Enhanced Oil Recovery and CO{sub 2} storage purposes. Enhanced Oil Recovery is a proven concept, widely used to recover otherwise inaccessible petroleum reserves. While post-combustion CO{sub 2} capture technologies have been tested at the pilot scale on coal power plant flue gas, they have not yet been demonstrated at a commercial scale and integrated with EOR and storage operations. Amine-based CO{sub 2} capture is the leading technology expected to be available commercially within this decade to enable CCS for utility and industrial facilities firing coal and waste fuels such as petroleum coke. However, traditional CO{sub 2} capture process utilizing commercial amine solvents is very energy intensive for regeneration and is also susceptible to solvent degradation by oxygen as well as SOx and NO{sub 2} in the flue gas, resulting in large operating costs. The large volume of combustion flue gas with its low CO{sub 2} concentration requires large equipment sizes, which together with the

  11. Synthesis of unstable cyclic peroxides for chemiluminescence studies

    Bartoloni, Fernando H.; Oliveira, Marcelo A. de; Augusto, Felipe A.; Ciscato, Luiz Francisco M.L.; Bastos, Erick L.; Baader, Wilhelm J., E-mail: wjbaader@iq.usp.br [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica. Dept. de Quimica Fundamental

    2012-11-15

    Cyclic four-membered ring peroxides are important high-energy intermediates in a variety of chemi and bioluminescence transformations. Specifically, a-peroxy lactones (1,2-dioxetanones) have been considered as model systems for efficient firefly bioluminescence. However, the preparation of such highly unstable compounds is extremely difficult and, therefore, only few research groups have been able to study the properties of these substances. In this study, the synthesis, purification and characterization of three 1,2-dioxetanones are reported and a detailed procedure for the known synthesis of diphenoyl peroxide, another important model compound for the chemical generation of electronically excited states, is provided. For most of these peroxides, the complete spectroscopic characterization is reported here for the first time. (author)

  12. Development of an RFQ linac for unstable nuclei

    Arai, S.; Imanishi, A.; Morimoto, T.; Shibuya, S.; Tojyo, E.; Tokuda, N.

    1990-05-01

    A split coaxial RFQ (SCRFQ) is being developed for accelerating unstable nuclei with a charge-to-mass ratio larger than 1/60 from 1 to 170 keV/u in the JHP heavy-ion linac. The SCRFQ is equipped with modulated vanes to generate ideal quadrupole and accelerating fields. The fundamental problems on the SCRFQ have been clarified and solved through studies on a cold model, and the excellent accelerating performance has been confirmed by using a proton accelerating model working at 50 MHz. A 25.5-MHz prototype for the JHP SCRFQ is now under development. The prototype, 2.1 m in length and 0.9 m in diameter, will accelerate ions with a charge-to-mass ratio larger than 1/30 from 1 to 45 keV/u. Low-power tests conducted so far show that the prototype cavity has good rf characteristics. (author)

  13. An extended model for ultrasonic-based enhanced oil recovery with experimental validation.

    Mohsin, Mohammed; Meribout, Mahmoud

    2015-03-01

    This paper suggests a new ultrasonic-based enhanced oil recovery (EOR) model for application in oil field reservoirs. The model is modular and consists of an acoustic module and a heat transfer module, where the heat distribution is updated when the temperature rise exceeds 1 °C. The model also considers the main EOR parameters which includes both the geophysical (i.e., porosity, permeability, temperature rise, and fluid viscosity) and acoustical (e.g., acoustic penetration and pressure distribution in various fluids and mediums) properties of the wells. Extended experiments were performed using powerful ultrasonic waves which were applied for different kind of oils & oil saturated core samples. The corresponding results showed a good matching with those obtained from simulations, validating the suggested model to some extent. Hence, a good recovery rate of around 88.2% of original oil in place (OOIP) was obtained after 30 min of continuous generation of ultrasonic waves. This leads to consider the ultrasonic-based EOR as another tangible solution for EOR. This claim is supported further by considering several injection wells where the simulation results indicate that with four (4) injection wells; the recovery rate may increase up-to 96.7% of OOIP. This leads to claim the high potential of ultrasonic-based EOR as compared to the conventional methods. Following this study, the paper also proposes a large scale ultrasonic-based EOR hardware system for installation in oil fields. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Coherent production on nuclei and measurements of total cross sections for unstable particles

    Czyz, W.; Zielinski, M.

    1980-01-01

    The Koelbig-Margolis Formula is fitted to some explicity nonperturbative models of diffractive production. It is shown that, in spite of the fact that the standard procedure of fitting the integrated cross sections may give acceptable fits, thus obtained ''cross sections of unstable particles'', grossly disagree with the ''true'' cross sections known exactly from the models. (author)

  15. Potential use of California lignite and other alternate fuel for enhanced oil recovery. Phase I and II. Final report. [As alternative fuels for steam generation in thermal EOR

    Shelton, R.; Shimizu, A.; Briggs, A.

    1980-02-01

    The Nation's continued reliance on liquid fossil fuels and decreasing reserves of light oils gives increased impetus to improving the recovery of heavy oil. Thermal enhanced oil recovery EOR techniques, such as steam injection, have generally been the most effective for increasing heavy oil production. However, conventional steam generation consumes a large fraction of the produced oil. The substitution of alternate (solid) fuels would release much of this consumed oil to market. This two-part report focuses on two solid fuels available in California, the site of most thermal EOR - petroleum coke and lignite. Phase I, entitled Economic Analysis, shows detailed cost comparisons between the two candidate fuels and also with Western coal. The analysis includes fuels characterizations, process designs for several combustion systems, and a thorough evaluation of the technical and economic uncertainties. In Phase II, many technical parameters of petroleum coke combustion were measured in a pilot-plant fluidized bed. The results of the study showed that petroleum coke combustion for EOR is feasible and cost effective in a fluidized bed combustor.

  16. Weak gravitational lensing as a method to constrain unstable dark matter

    Wang Meiyu; Zentner, Andrew R.

    2010-01-01

    The nature of the dark matter remains a mystery. The possibility of an unstable dark matter particle decaying to invisible daughter particles has been explored many times in the past few decades. Meanwhile, weak gravitational lensing shear has gained a lot of attention as a probe of dark energy, though it was previously considered a dark matter probe. Weak lensing is a useful tool for constraining the stability of the dark matter. In the coming decade a number of large galaxy imaging surveys will be undertaken and will measure the statistics of cosmological weak lensing with unprecedented precision. Weak lensing statistics are sensitive to unstable dark matter in at least two ways. Dark matter decays alter the matter power spectrum and change the angular diameter distance-redshift relation. We show how measurements of weak lensing shear correlations may provide the most restrictive, model-independent constraints on the lifetime of unstable dark matter. Our results rely on assumptions regarding nonlinear evolution of density fluctuations in scenarios of unstable dark matter and one of our aims is to stimulate interest in theoretical work on nonlinear structure growth in unstable dark matter models.

  17. On the Velocity of Moving Relativistic Unstable Quantum Systems

    K. Urbanowski

    2015-01-01

    Full Text Available We study properties of moving relativistic quantum unstable systems. We show that in contrast to the properties of classical particles and quantum stable objects the velocity of freely moving relativistic quantum unstable systems cannot be constant in time. We show that this new quantum effect results from the fundamental principles of the quantum theory and physics: it is a consequence of the principle of conservation of energy and of the fact that the mass of the quantum unstable system is not defined. This effect can affect the form of the decay law of moving relativistic quantum unstable systems.

  18. GRAVITATIONALLY UNSTABLE FLAMES: RAYLEIGH-TAYLOR STRETCHING VERSUS TURBULENT WRINKLING

    Hicks, E. P.; Rosner, R.

    2013-01-01

    In this paper, we provide support for the Rayleigh-Taylor-(RT)-based subgrid model used in full-star simulations of deflagrations in Type Ia supernovae explosions. We use the results of a parameter study of two-dimensional direct numerical simulations of an RT unstable model flame to distinguish between the two main types of subgrid models (RT or turbulence dominated) in the flamelet regime. First, we give scalings for the turbulent flame speed, the Reynolds number, the viscous scale, and the size of the burning region as the non-dimensional gravity (G) is varied. The flame speed is well predicted by an RT-based flame speed model. Next, the above scalings are used to calculate the Karlovitz number (Ka) and to discuss appropriate combustion regimes. No transition to thin reaction zones is seen at Ka = 1, although such a transition is expected by turbulence-dominated subgrid models. Finally, we confirm a basic physical premise of the RT subgrid model, namely, that the flame is fractal, and thus self-similar. By modeling the turbulent flame speed, we demonstrate that it is affected more by large-scale RT stretching than by small-scale turbulent wrinkling. In this way, the RT instability controls the flame directly from the large scales. Overall, these results support the RT subgrid model.

  19. Monitoring of EOR operations by electrical prospecting. 2; Denki tansaho ni yoru sekiyu kyosei kaishuho no monitoring. 2

    Ushijima, K; Mizunaga, H; Tanaka, T; Masuda, K [Kyushu University, Fukuoka (Japan). Faculty of Engineering; Tamagawa, T [Japex Jeoscience Institute, Tokyo (Japan)

    1996-10-01

    Fluid flow tomography (FFT) was applied to monitor the behavior of underground fluid in steam enhanced oil recovery (EOR) for oil sand reservoirs. FFT uses electrode arrangement of a mise-a-la-masse method, and continuously measures time variation in charged and spontaneous potential at various surface points to obtain realtime the images of underground seepage flow. It continuously measures ground surface potentials of 120 channels at intervals of 2s by applying alternative DC between a casing pipe and distant current electrode. It separates charged and spontaneous potential components, and converts them into time series data. It estimates the time and spacial distributions of seepage flow from time variation in spontaneous potential. It determines the change rate distribution of time-sliced apparent resistivity from charged potential to estimate the scale and area of seepage flow. As the experimental result, positive and negative electrodes in the change rate distribution were observed, and the direction connecting each electrode agreed with that of resistivity anomaly. FFT could observe realtime time variation in apparent resistivity due to steam injection. 9 refs., 7 figs.

  20. Study on the reutilization of clear fracturing flowback fluids in surfactant flooding with additives for Enhanced Oil Recovery (EOR.

    Caili Dai

    Full Text Available An investigation was conducted to study the reutilization of clear fracturing flowback fluids composed of viscoelastic surfactants (VES with additives in surfactant flooding, making the process more efficient and cost-effective. The clear fracturing flowback fluids were used as surfactant flooding system with the addition of α-olefin sulfonate (AOS for enhanced oil recovery (EOR. The interfacial activity, emulsification activity and oil recovery capability of the recycling system were studied. The interfacial tension (IFT between recycling system and oil can be reduced by 2 orders of magnitude to 10(-3 mN/m, which satisfies the basic demand of surfactant flooding. The oil can be emulsified and dispersed more easily due to the synergetic effect of VES and AOS. The oil-wet surface of quartz can be easily converted to water-wet through adsorption of surfactants (VES/AOS on the surface. Thirteen core plug flooding tests were conducted to investigate the effects of AOS concentrations, slug sizes and slug types of the recycling system on the incremental oil recovery. The investigations prove that reclaiming clear fracturing flowback fluids after fracturing operation and reuse it in surfactant flooding might have less impact on environment and be more economical.

  1. Study on the reutilization of clear fracturing flowback fluids in surfactant flooding with additives for Enhanced Oil Recovery (EOR).

    Dai, Caili; Wang, Kai; Liu, Yifei; Fang, Jichao; Zhao, Mingwei

    2014-01-01

    An investigation was conducted to study the reutilization of clear fracturing flowback fluids composed of viscoelastic surfactants (VES) with additives in surfactant flooding, making the process more efficient and cost-effective. The clear fracturing flowback fluids were used as surfactant flooding system with the addition of α-olefin sulfonate (AOS) for enhanced oil recovery (EOR). The interfacial activity, emulsification activity and oil recovery capability of the recycling system were studied. The interfacial tension (IFT) between recycling system and oil can be reduced by 2 orders of magnitude to 10(-3) mN/m, which satisfies the basic demand of surfactant flooding. The oil can be emulsified and dispersed more easily due to the synergetic effect of VES and AOS. The oil-wet surface of quartz can be easily converted to water-wet through adsorption of surfactants (VES/AOS) on the surface. Thirteen core plug flooding tests were conducted to investigate the effects of AOS concentrations, slug sizes and slug types of the recycling system on the incremental oil recovery. The investigations prove that reclaiming clear fracturing flowback fluids after fracturing operation and reuse it in surfactant flooding might have less impact on environment and be more economical.

  2. Study of polyacrylamide-surfactant system on the water–oil interface properties and rheological properties for EOR

    S.Z. Mahdavi

    2017-12-01

    Full Text Available Nowadays, due to the remarkable oil reduction in oil fields, enhanced oil recovery (EOR techniques have been considered by a large number of scientists and company. Situ oil extraction is normally done by these techniques with high efficiency. In this particular study, five different surface active agents (surfactant, two kinds of oil with various API, two kinds of sulfonated polyacrylamide, two different electrolyte solutions with various TDS and two distinctive alcohols were tested and evaluated. An optimal formulation in terms of the properties and quantity of materials has to be used in order to enhance oil recovery, achieved by investigation of surface tension and the phase behavior of mentioned substances. Rheological behavior of polymer flooding and surfactant was studied. Employing this formulation, the maximum micro emulsion of oil in water occurred. Due to the synergy between surfactant and alcohol (as a co-surfactant, relatively lower amounts of surfactants were used which led to the dip in the cost of operation, and ultimately the efficiency of operation improved.

  3. Is 'bosonic matter' unstable in 2D?

    Manoukian, E B

    2003-01-01

    An upper bound is derived for the exact ground-state energy in 2D, E sub N <= -(me sup 4 /2 h-bar sup 2)(N sup 3 sup / sup 2 /50 pi sup 2), of 'bosonic matter' consisting of N positive and N negative charges with Coulombic interactions. This is to be compared with the classic N sup 7 sup / sup 5 3D-law of Dyson and gives rise to a more 'violent' collapse of such matter in 2D for large N. The derivation is based on a rigorous analysis which, in the process, controls the negative part of the Hamiltonian over its positive kinetic energy part and detailed estimates needed for counting trial wavefunctions of arbitrary states. A formal dimensional analysis in the style of Dyson alone shows, in arbitrary dimensions of space d = 1, 2, ..., that E sub N approx = -(me sup 4 /2 h-bar sup 2)C sub d N suprho, rho = (d + 4)/(d + 2), where C sub d is a positive constant depending on d, consistent with our rigorous bound, and we are led to conjecture that 'bosonic matter' is unstable in all dimensions.

  4. Superluminal warp drives are semiclassically unstable

    Finazzi, S; Liberati, S [SISSA, via Beirut 2-4, Trieste 34151, Italy and INFN sezione di Trieste (Italy); Barcelo, C, E-mail: finazzi@sissa.i, E-mail: liberati@sissa.i, E-mail: carlos@iaa.e [Instituto de Astrofisica de AndalucIa, CSIC, Camino Bajo de Huetor 50, 18008 Granada (Spain)

    2010-04-01

    Warp drives are very interesting configurations of General Relativity: they provide a way to travel at superluminal speeds, albeit at the cost of requiring exotic matter to build them. Even if one succeeded in providing the necessary exotic matter, it would still be necessary to check whether they would survive to the switching on of quantum effects. Semiclassical corrections to warp-drive geometries created out of an initially flat spacetime have been analyzed in a previous work by the present authors in special locations, close to the wall of the bubble and in its center. Here, we present an exact numerical analysis of the renormalized stress-energy tensor (RSET) in the whole bubble. We find that the the RSET will exponentially grow in time close to the front wall of the superluminal bubble, after some transient terms have disappeared, hence strongly supporting our previous conclusion that the warp-drive geometries are unstable against semiclassical back-reaction. This result seems to implement the chronology protection conjecture, forbiddig the set up of a structure potentially dangerous for causality.

  5. Unstable mixed convective transport in groundwater

    Schincariol, R.A.; Schwartz, F.W.

    1990-01-01

    This study is an experimental investigation of variable density groundwater flow in homogeneous and lenticular porous media. A solution of 500 mg/l Rhodamine WT dye served as the carrier for various concentrations of solute (NaCl) introduced into a two-dimensional flow tank at concentrations ranging from 1000 to 100,000 mg/l. At the scale of the experiments, mass transport depends upon both forced and free convection. In addition, density differences as low as 0.008 g/cm 3 (1000 mg/l NaCl) between a plume of dense water and ambient groundwater in homogeneous medium produces gravitational instabilities at realistic groundwater velocities. These instabilities are manifest by lobe-shaped protuberances that formed first along the bottom edge of the plume and later within the plume. As the density difference increases to 0.0015 g/cm 3 (2000 mg/l NaCl), 0.0037 g/cm 3 (5000 mg/l NaCl) or higher, this unstable mixing due to convective dispersion significantly alters the spreading process, resulting in a large degree of vertical spreading of the plume. In a lenticular medium the combination of convective dispersion and nonuniform flow due to heterogeneities results in relatively large dispersion. Scale considerations indicate that convective dispersion may provide an important component of mixing at the field scale. (Author) (30 refs., 12 figs., 3 tabs.)

  6. Metastable and unstable cellular solidification of colloidal suspensions

    Deville, Sylvain; Maire, Eric; Bernard-Granger, Guillaume; Lasalle, Audrey; Bogner, Agnès; Gauthier, Catherine; Leloup, Jérôme; Guizard, Christian

    2009-12-01

    Colloidal particles are often seen as big atoms that can be directly observed in real space. They are therefore becoming increasingly important as model systems to study processes of interest in condensed-matter physics such as melting, freezing and glass transitions. The solidification of colloidal suspensions has long been a puzzling phenomenon with many unexplained features. Here, we demonstrate and rationalize the existence of instability and metastability domains in cellular solidification of colloidal suspensions, by direct in situ high-resolution X-ray radiography and tomography observations. We explain such interface instabilities by a partial Brownian diffusion of the particles leading to constitutional supercooling situations. Processing under unstable conditions leads to localized and global kinetic instabilities of the solid/liquid interface, affecting the crystal morphology and particle redistribution behaviour.

  7. Managing risk in an unstable world.

    Bremmer, Ian

    2005-06-01

    With emerging markets like China and politically unstable countries like Saudi Arabia figuring more than ever into companies' investment calculations, business leaders are turning to political risk analysis to measure the impact of politics on potential markets, minimize risks, and make the most of global opportunities. But political risk is more subjective than its economic counterpart. It is influenced by the passage of laws, the foibles of government leaders, and the rise of popular movements. So corporate leaders must grapple not just with broad, easily observable trends but also with nuances of society and even quirks of personality. And those hard-to-quantify factors must constantly be pieced together into an ongoing narrative within historical and regional contexts. As goods, services, information, ideas, and people cross borders today with unprecedented velocity, corporations debating operational or infrastructural investments abroad increasingly need objective, rigorous assessments. One tool for measuring and presenting stability data, for example, incorporates 20 composite indicators of risk in emerging markets and scores risk variables according to both their structural and their temporal components. The indicators are then organized into four equally weighted subcategories whose ratings are aggregated into a single stability score. Countries are ranked on a scale of zero (a failed state) to100 (a fully institutionalized, stable democracy). Companies can buy political risk analyses from consultants or, as some large energy and financial services organizations have done, develop them in-house. Either way, a complete and accurate picture of any country's risk requires analysts with strong reportorial skills; timely, accurate data on a variety of social and political trends; and a framework for evaluating the impact of individual risks on stability.

  8. Noncontiguous double-level unstable spinal injuries.

    Takami, Masanari; Okada, Motohiro; Enyo, Yoshio; Iwasaki, Hiroshi; Yamada, Hiroshi; Yoshida, Munehito

    2017-01-01

    Noncontiguous double-level unstable spinal injuries (NDUSI) are uncommon and have not been well described. In this study, we aimed to better understand the patterns of NDUSI, in order to recommend proper diagnostic and treatment methods, as well as to raise awareness among traumatologists about the possibility of these uncommon injuries. A total of 710 consecutive patients with spine fractures were treated for >9 years since 2007 at a single regional trauma center. Of them, 18 patients with NDUSI were reviewed retrospectively. The incidence of NDUSI was 2.5 % of all spine fractures. In 17 of 18 patients (94.7 %), NDUSI was caused by a high-energy trauma. Nine patients (50.0 %) exhibited complete neurological deficit. Spinal cord injury occurred in the cranial injured region in all American Spinal Injury Association grade A cases. In one case, a second fracture was overlooked at the initial examination. NDUSI are common in cases of high-energy trauma and should be taken into consideration at the initial examination. A second fracture may be easily overlooked because of the high frequency of concomitant severe spinal cord injury in the cranial injured region and/or loss of consciousness due to associated injuries. To avoid overlooking injuries, full spine computed tomography is useful at the initial examination. Operative reduction and internal fixation with instrumentation through a posterior approach is recommendable for cases of NDUSI. In elderly patients, a very rapid stabilizing surgery should be planned before aspiration pneumonia occurs or the pulmonary condition worsens.

  9. High energy nucleus-nucleus scattering and matter radius of unstable nucleus

    Sato, H.; Okuhara, Y.

    1985-07-01

    The interaction cross sections of high energy nucleus-nucleus scattering have been studied with the Glauber Model and Hartree-Fock like variational calculation for the nuclear structure. It is found that the experimental interaction cross sections of the light unstable nucleus-stable nucleus scatterings measured by INS-LBL collaboration are well reproduceable. (author)

  10. Compositional Simulation of In-Situ Combustion EOR: A Study of Process Characteristics

    Jain, Priyanka; Stenby, Erling Halfdan; von Solms, Nicolas

    2010-01-01

    In order to facilitate the study of the influence of reservoir process characteristics in In-Situ combustion modeling and advance the work of Kristensen et al. in this domain; a fully compositional In-situ combustion (ISC) model of Virtual Kinetic Cell (VKC; single-cell model) for laboratory scale....... This incorporates fourteen pseudo components and fourteen reactions (distributed amongst thermal cracking, low temperature oxidation and high temperature oxidation). The paper presents a set of derivative plots indicating that reservoir process characterization in terms of thermal behavior of oil can be well...... construed in terms of thermo-oxidative sensitivity of SARA fractions. It can be interpreted from the results that operating parameters like air injection rate, oxygen feed concentration and activation energy have significant influence on oil recovery; an increase in air injection rate can lead to cooling...

  11. Improving Chemical EOR Simulations and Reducing the Subsurface Uncertainty Using Downscaling Conditioned to Tracer Data

    Torrealba, Victor A.; Hoteit, Hussein; Chawathe, Adwait

    2017-01-01

    and thermodynamic phase split, the impact of grid downscaling on CEOR simulations is not well understood. In this work, we introduce a geostatistical downscaling method conditioned to tracer data to refine a coarse history-matched WF model. This downscaling process

  12. Stable, metastable and unstable solutions of a spin-1 Ising system based on the free energy surfaces

    Keskİin, Mustafa; Özgan, Şükrü

    1990-04-01

    Stable, metastable and unstable solutions of a spin-1 Ising model with bilinear and biquadratic interactions are found by using the free energy surfaces. The free energy expression is obtained in the lowest approximation of the cluster variation method. All these solutions are shown in the two-dimensional phase space, especially the unstable solutions which in some cases are difficult to illustrate in the two-dimensional phase space, found by Keskin et al. recently.

  13. Constraining Polarized Foregrounds for EoR Experiments. II. Polarization Leakage Simulations in the Avoidance Scheme

    Nunhokee, C. D.; Bernardi, G.; Foster, G.; Grobler, T. L. [Department of Physics and Electronics, Rhodes University, P.O. Box 94, Grahamstown, 6140 (South Africa); Kohn, S. A.; Aguirre, J. E.; Martinot, J. Z. E. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA (United States); Thyagarajan, N. [Arizona State University, School of Earth and Space Exploration, Tempe, AZ 85287 (United States); Dillon, J. S. [Berkeley Center for Cosmological Physics, Berkeley, CA 94720 (United States); Parsons, A. R., E-mail: cnunhokee@gmail.com [Dept. of Astronomy, University of California, Berkeley, CA 94720 (United States)

    2017-10-10

    A critical challenge in the observation of the redshifted 21 cm line is its separation from bright Galactic and extragalactic foregrounds. In particular, the instrumental leakage of polarized foregrounds, which undergo significant Faraday rotation as they propagate through the interstellar medium, may harmfully contaminate the 21 cm power spectrum. We develop a formalism to describe the leakage due to instrumental widefield effects in visibility-based power spectra measured with redundant arrays, extending the delay-spectrum approach presented in Parsons et al. We construct polarized sky models and propagate them through the instrument model to simulate realistic full-sky observations with the Precision Array to Probe the Epoch of Reionization. We find that the leakage due to a population of polarized point sources is expected to be higher than diffuse Galactic polarization at any k mode for a 30 m reference baseline. For the same reference baseline, a foreground-free window at k > 0.3 h Mpc{sup −1} can be defined in terms of leakage from diffuse Galactic polarization even under the most pessimistic assumptions. If measurements of polarized foreground power spectra or a model of polarized foregrounds are given, our method is able to predict the polarization leakage in actual 21 cm observations, potentially enabling its statistical subtraction from the measured 21 cm power spectrum.

  14. Generalization in adaptation to stable and unstable dynamics.

    Abdelhamid Kadiallah

    Full Text Available Humans skillfully manipulate objects and tools despite the inherent instability. In order to succeed at these tasks, the sensorimotor control system must build an internal representation of both the force and mechanical impedance. As it is not practical to either learn or store motor commands for every possible future action, the sensorimotor control system generalizes a control strategy for a range of movements based on learning performed over a set of movements. Here, we introduce a computational model for this learning and generalization, which specifies how to learn feedforward muscle activity in a function of the state space. Specifically, by incorporating co-activation as a function of error into the feedback command, we are able to derive an algorithm from a gradient descent minimization of motion error and effort, subject to maintaining a stability margin. This algorithm can be used to learn to coordinate any of a variety of motor primitives such as force fields, muscle synergies, physical models or artificial neural networks. This model for human learning and generalization is able to adapt to both stable and unstable dynamics, and provides a controller for generating efficient adaptive motor behavior in robots. Simulation results exhibit predictions consistent with all experiments on learning of novel dynamics requiring adaptation of force and impedance, and enable us to re-examine some of the previous interpretations of experiments on generalization.

  15. Restrictions in the realisation of multipass unstable resonators

    Strakhov, S Yu

    2009-01-01

    Main restrictions in the realisation of multipass unstable resonators caused by intracavity losses and large-scale aberrations are considered. The influence of intracavity losses on the laser radiation power and divergence is analysed based on the numerical simulation of an unstable resonator. The efficiency criterion for the unstable multipass resonator is proposed, which is proportional to the radiation brightness and takes into account the influence of the misalignment, thermal deformation and the main parameters of the active medium and resonator on the parameters of laser radiation. (resonators)

  16. [Treatment aspects of unstable angina. Costs and payments for DRG].

    Brunelli, C; Spallarossa, P; Pasdera, A; Bezante, G P; Zorzet, F; Rossettin, P

    1998-01-01

    Patients with unstable angina fall into a wide prognostic and therapeutic spectrum but, in general, have great access to specialty care and invasive procedures. In the modern era, in which admissions for unstable angina outnumber those for myocardial infarction, and growing economic pressures are placed on health care systems, cardiologists must re-examine clinical strategies for treating unstable angina in the light of health-cost accounting. The aims of the present study were to examine the current management of patients admitted to our cardiology department and to calculate the medical costs. A patient schedule was drawn up to prospectively register the number and type of cardiac processes carried out during hospitalization for all unstable angina patients in the period between March 1st and May 30th, 1995. Time (minutes) actually spent by both physicians and nurses for each cardiac process were carefully recorded in order to calculate the activity budget. The effective economic budget was built for each cardiac process taking into account salaries, consumable supplies, equipment service contracts, depreciation and indirect medical and non medical costs for CCU and ward. Based to the Diagnosis Related Groups (DRG) system, 53 out of 318 patients (16%) were admitted with documented or suspected unstable angina and allocated to discharge into four DRGs: DRG 140-medically treated unstable angina: 18 patients; DRG 124-unstable angina with angiography: 16 patients; DRG 122-unstable angina evolving in myocardial infarction: 6 patients; DRG 112-unstable angina with angioplasty: 13 patients. The mean cost for hospitalized patient with unstable angina was 5,574,958 Italian Liras (DRG 140 = 2,687,719; DRG 124 = 2,800,347; DRG 122 = 6,086,563; DRG 112 = 12,751,454). The difference in costs was essentially related to the procedures involved in medical care, DRGs with expensive cardiac processes having higher costs. Furthermore, these data show a deep discrepancy between

  17. Simulations for 21 cm radiation lensing at EoR redshifts

    Romeo, Alessandro; Metcalf, Robert Benton; Pourtsidou, Alkistis

    2018-02-01

    We introduce simulations aimed at assessing how well weak gravitational lensing of 21cm radiation from the Epoch of Reionization (z ˜ 8) can be measured by a Square Kilometre Array (SKA)-like radio telescope. A simulation pipeline has been implemented to study the performance of lensing reconstruction techniques. We show how well the lensing signal can be reconstructed using the 3D quadratic lensing estimator in Fourier space assuming different survey strategies. The numerical code introduced in this work is capable of dealing with issues that cannot be treated analytically such as the discreteness of visibility measurements and the inclusion of a realistic model for the antennas distribution. This paves the way for future numerical studies implementing more realistic re-ionization models, foreground subtraction schemes, and testing the performance of lensing estimators that take into account the non-Gaussian distribution of HI after re-ionization. If multiple frequency channels covering z ˜ 7-11.6 are combined, Phase 1 of SKA-Low should be able to obtain good quality images of the lensing potential with a total resolution of ˜1.6 arcmin. The SKA-Low Phase 2 should be capable of providing images with high fidelity even using data from z ˜ 7.7 to 8.3. We perform tests aimed at evaluating the numerical implementation of the mapping reconstruction. We also discuss the possibility of measuring an accurate lensing power spectrum. Combining data from z ˜ 7 to 11.6 using the SKA2-Low telescope model, we find constraints comparable to sample variance in the range L < 1000, even for survey areas as small as 25 deg2.

  18. Characterization of glass filter micromodels used for polymer EOR flooding experiments

    Foedisch, H.; Wegner, J.; Hincapie-Reina, R.; Ganzer, L. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE

    2013-08-01

    This work is conducted as part of the research project DGMK 746 - ''Experimental and Numerical Analysis of Polymer Flooding Processes Using Micromodels - From Pore Scale to Continuum Scale''. The industry standard to assess polymer flood performance is through flooding experiments with cores or plugs. A complement to flooding experiments in cores is represented by micromodels such as glass filters, which resemble real porous media through their porous structures. In this way, an almost unlimited number of equivalent samples can be produced. Moreover, compared to cores the micromodels enable visual access to the flooding process enabling a detailed process description. The sintered glass filters used in this work represent one way to make displacement processes inside artificial structures visible. However, challenges exist to transfer the results obtained from models composed of glass to real plugs or rock sections. Therefore, this study focuses on the comparison of glass filter micromodels and real rock samples composed of Bentheimer sandstone. We determine water permeability and oil-water relative permeability endpoints with flooding experiments, compare capillary pressure functions of the glass models obtained from mercury porosimetry analysis with results from Bentheimer sandstone, and characterize the glass filter with respect of connate water saturation using NMR-spectroscopy and porosity obtained from pycnometer measurements. (orig.)

  19. Characterization of the structural collapse undergone by an unstable system of ultrasoft particles

    Prestipino, Santi; Malescio, Gianpietro

    2016-09-01

    The effective repulsion between macromolecules such as polymer chains or dendrimers is everywhere finite, implying that interaction centers can even coincide. If, in addition, the large-distance attraction is sufficiently strong, then the system is driven unstable. An unstable system lacks a conventional thermodynamics since, in the infinite-size limit, it eventually collapses to a finite-size cluster (for instance, a polymer dispersion undergoes irreversible coagulation when increasing the amount of dissolved salt beyond a certain limit). Using a double-Gaussian (DG) potential for demonstration, we study the phase behavior of a system of ultrasoft particles as a function of the attraction strength η. Above a critical threshold ηc, the DG system is unstable but its collective behavior is far from trivial since two separate regions of the thermodynamic plane can be identified, based on the value taken by the average waiting time for collapse: this is finite and small on one side of the boundary, while presumably infinite in the other region. In order to make sense of this evidence, we consider a stable system of particles interacting through a DG potential augmented with a hard core (stabilized DG, or SDG potential). We provide arguments supporting the view that the boundary line of the unstable DG model is the remnant of the spinodal line of a fluid-fluid phase transition occurring in the SDG model when the hard-core diameter is sent to zero.

  20. Experimental Design of a Polymeric Solution to Improve the Mobility Ratio in a Reservoir previous implementation of a pilot project of EOR

    Vanessa Cuenca

    2016-12-01

    Full Text Available This paper describes experimental formulations of polymeric solutions through lab evaluations with the objective of finding optimum solution concentration to fluid mobility in reservoirs as previous step before implementing a pilot project of enhanced oil recovery. The polymers, firstly, were selected based on the properties from fluids from reservoir. Two types of polymers were used TCC-330 and EOR909 and the experimental tests were: thermal stability, compatibility, adsorption, salinity, and displacement. The design with the best results was with polymer TCC-330 at 1,500 ppm concentration.

  1. Coordinated protection of the population in emergencies in Switzerland: The National Emergency Operations Centre (NAZ) and the Emergency Organisation Radioactivity (EOR)

    Brunner, H.H.

    1992-01-01

    As consequence of the nuclear weapons tests Switzerland has since 30 years expert commissions, concepts, monitoring networks, monitoring and emergency teams for the protection of the population following radiological accidents of all types inside or outside the country. Thus Chernobyl hit a prepared country - except information. The Radiological Emergency Organisation (EOR) and its National Emergency Operations Centre (NAZ) have up-to-date legal bases, concepts and operational means. Besides radiological events, NAZ deals also with chemical accidents, satellite, satellite crashes and dam breaks. Unique is the coordinated use of the combined means of civil authorities, civil defense and army in all strategic cases. (author)

  2. Evolution of the Quasar Luminosity Function: Implications for EoR-21cm

    Kulkarni, Girish; Choudhury, Tirthankar Roy; Puchwein, Ewald; Haehnelt, Martin G.

    2018-05-01

    We present predictions for the spatial distribution of 21 cm brightness temperature fluctuations from high-dynamic-range simulations for AGN-dominated reionization histories that have been tested against available Lyα and CMB data. We model AGN by extrapolating the observed Mbh-σ relation to high redshifts and assign them ionizing emissivities consistent with recent UV luminosity function measurements. AGN-dominated reionization histories increase the variance of the 21 cm emission by a factor of up to ten compared to similar reionization histories dominated by faint galaxies, to values close to 100 mK2 at scales accessible to experiments (k <~ 1 cMpc-1h). This is lower than the sensitivity reached by ongoing experiments by only a factor of about two or less. AGN dominated reionization should be easily detectable by LOFAR (and later HERA and SKA1) at their design sensitivity.

  3. Small Kerr-anti-de Sitter black holes are unstable

    Cardoso, Vitor; Dias, Oscar J.C.

    2004-01-01

    Superradiance in black hole spacetimes can trigger instabilities. Here we show that, due to superradiance, small Kerr-anti-de Sitter black holes are unstable. Our demonstration uses a matching procedure, in a long wavelength approximation

  4. Numerical investigations on unstable direct contact condensation of cryogenic fluids

    Jayachandran, K. N.; Arnab, Roy; Parthasarathi, Ghosh

    2017-02-01

    A typical problem of Direct Contact Condensation (DCC) occurs at the liquid oxygen (LOX) booster turbopump exit of oxidiser rich staged combustion cycle based semi-cryogenic rocket engines, where the hot gas mixture (predominantly oxygen and small amounts of combustion products) that runs the turbine mixes with LOX from the pump exit. This complex multiphase phenomena leads to the formation of solid CO2 & H2O, which is undesirable for the functioning of the main LOX turbopump. As a starting point for solving this complex problem, in this study, the hot gas mixture is taken as pure oxygen and hence, DCC of pure oxygen vapour jets in subcooled liquid oxygen is simulated using the commercial CFD package ANSYS CFX®. A two fluid model along with the thermal phase change model is employed for capturing the heat and mass transfer effects. The study mainly focuses on the subsonic DCC bubbling regime, which is reported as unstable with bubble formation, elongation, necking and collapsing effects. The heat transfer coefficients over a period of time have been computed and the various stages of bubbling have been analysed with the help of vapour volume fraction and pressure profiles. The results obtained for DCC of oxygen vapour-liquid mixtures is in qualitative agreement with the experimental results on DCC of steam-water mixtures.

  5. Effect of multi-component ions exchange on low salinity EOR: Coupled geochemical simulation study

    Ehsan Pouryousefy

    2016-09-01

    Upon combining the simulation and experimental results, we concluded that the multi-component ion exchange is not the sole mechanism behind low salinity effect for two reasons. First, almost 10% additional oil recovery was observed from the experiments by injecting the 2000 ppm CaCl2 compared with 50,000 ppm CaCl2 solutions. Even though in both cases the surface is expected to be fully saturated with Ca2+ according to the geochemical modelling. Second, 6% incremental oil recovery was achieved from the experiments by injecting 2000 ppm NaCl solution compared with that of 50,000 ppm NaCl. Although 25% incremental adsorption of divalent cations (Ca2+ were presented during the flooding of the 2000 ppm NaCl solution. Therefore, it is worth noting that the electrical double layer expansion due to the ion exchange needs to be taken into account to pinpoint the mechanism(s of low-salinity water effect.

  6. Laboratory and simulation approach to the polymer EOR evaluation in German reservoir characteristics

    Zheng, S.; Hincapie-Reina, R.; Ganzer, L. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE

    2013-08-01

    Nowadays, polymer flooding is widely used as it enhances oil recovery. As polymer has relatively higher viscosity than water, which leads to better mobility ratio compared to it, and thus better sweep efficiency. However, this technique is limited by some factors. As normal polymers are not tolerant to high temperature or salinity or hardness, which lead to lose of most their viscosity, and thus lost their function in enhanced oil recovery. Therefore, new polymers which are resistant to high temperature, high salinity or other factors which may happen in the reservoir should be employed. In that direction, the present work focus in characterize two different polymers, Flopaam AN 125 and ZLPAM 22051, how they would be influenced by polymer concentration, salinity, shear rate and temperature, and to predict how they would work in the reservoir. A synthetic brine from a German reservoir (Valendis, Suderbruch Field) is used to analyze the polymer. In many different previous experiments is observed the divalent and monovalent effect of salt in polymers was carried out. Rheology characterization was done under the reservoir conditions to get the best approximation related to concentration, shear rate and temperature effect; filtration ratio and filterability plot are used as a quality check for the solutions. Finally, all the data is used into the Polymer Flood Predictive Model (PFPM), to figure out how polymer acted in German typical reservoir conditions, and the specific incremental in oil recovery and effect due the possible polymer application, which might provide information for future polymer flooding application decisions. (orig.)

  7. Study on unstable fracture characteristics of light water reactor piping

    Kurihara, Ryoichi

    1998-08-01

    Many testing studies have been conducted to validate the applicability of the leak before break (LBB) concept for the light water reactor piping in the world. It is especially important among them to clarify the condition that an inside surface crack of the piping wall does not cause an unstable fracture but ends in a stable fracture propagating only in the pipe thickness direction, even if the excessive loading works to the pipe. Pipe unstable fracture tests performed in Japan Atomic Energy Research Institute had been planned under such background, and clarified the condition for the cracked pipe to cause the unstable fracture under monotonous increase loading or cyclic loading by using test pipes with the inside circumferential surface crack. This paper examines the pipe unstable fracture by dividing it into two parts. One is the static unstable fracture that breaks the pipe with the inside circumferential surface crack by increasing load monotonously. Another is the dynamic unstable fracture that breaks the pipe by the cyclic loading. (author). 79 refs

  8. Synchronizing movements with the metronome: nonlinear error correction and unstable periodic orbits.

    Engbert, Ralf; Krampe, Ralf Th; Kurths, Jürgen; Kliegl, Reinhold

    2002-02-01

    The control of human hand movements is investigated in a simple synchronization task. We propose and analyze a stochastic model based on nonlinear error correction; a mechanism which implies the existence of unstable periodic orbits. This prediction is tested in an experiment with human subjects. We find that our experimental data are in good agreement with numerical simulations of our theoretical model. These results suggest that feedback control of the human motor systems shows nonlinear behavior. Copyright 2001 Elsevier Science (USA).

  9. Computed Tomography Angiography Evaluation of Risk Factors for Unstable Intracranial Aneurysms.

    Wang, Guang-Xian; Gong, Ming-Fu; Wen, Li; Liu, Lan-Lan; Yin, Jin-Bo; Duan, Chun-Mei; Zhang, Dong

    2018-03-19

    To evaluate risk factors for instability in intracranial aneurysms (IAs) using computed tomography angiography (CTA). A total of 614 consecutive patients diagnosed with 661 IAs between August 2011 and February 2016 were reviewed. Patients and IAs were divided into stable and unstable groups. Along with clinical characteristics, IA characteristics were evaluated by CTA. Multiple logistic regression analysis was used to identify the independent risk factors associated with unstable IAs. Receiver operating characteristic (ROC) curve analysis was performed on the final model, and optimal thresholds were obtained. Patient age (odds ratio [OR], 0.946), cerebral atherosclerosis (CA; OR, 0.525), and IAs located at the middle cerebral artery (OR, 0.473) or internal carotid artery (OR, 0.512) were negatively correlated with instability, whereas IAs with irregular shape (OR, 2.157), deep depth (OR, 1.557), or large flow angle (FA; OR, 1.015) were more likely to be unstable. ROC analysis revealed threshold values of age, depth, and FA of 59.5 years, 4.25 mm, and 87.8°, respectively. The stability of IAs is significantly affected by several factors, including patient age and the presence of CA. IA shape and location also have an impact on the stability of IAs. Growth into an irregular shape, with a deep depth, and a large FA are risk factors for a change in IAs from stable to unstable. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. A genetic fuzzy system for unstable angina risk assessment.

    Dong, Wei; Huang, Zhengxing; Ji, Lei; Duan, Huilong

    2014-02-18

    Unstable Angina (UA) is widely accepted as a critical phase of coronary heart disease with patients exhibiting widely varying risks. Early risk assessment of UA is at the center of the management program, which allows physicians to categorize patients according to the clinical characteristics and stratification of risk and different prognosis. Although many prognostic models have been widely used for UA risk assessment in clinical practice, a number of studies have highlighted possible shortcomings. One serious drawback is that existing models lack the ability to deal with the intrinsic uncertainty about the variables utilized. In order to help physicians refine knowledge for the stratification of UA risk with respect to vagueness in information, this paper develops an intelligent system combining genetic algorithm and fuzzy association rule mining. In detail, it models the input information's vagueness through fuzzy sets, and then applies a genetic fuzzy system on the acquired fuzzy sets to extract the fuzzy rule set for the problem of UA risk assessment. The proposed system is evaluated using a real data-set collected from the cardiology department of a Chinese hospital, which consists of 54 patient cases. 9 numerical patient features and 17 categorical patient features that appear in the data-set are selected in the experiments. The proposed system made the same decisions as the physician in 46 (out of a total of 54) tested cases (85.2%). By comparing the results that are obtained through the proposed system with those resulting from the physician's decision, it has been found that the developed model is highly reflective of reality. The proposed system could be used for educational purposes, and with further improvements, could assist and guide young physicians in their daily work.

  11. Aqueous Hybrids of Silica Nanoparticles and Hydrophobically Associating Hydrolyzed Polyacrylamide Used for EOR in High-Temperature and High-Salinity Reservoirs

    Dingwei Zhu

    2014-06-01

    Full Text Available Water-soluble polymers are known to be used in chemically enhanced oil recovery (EOR processes, but their applications are limited in high-temperature and high-salinity oil reservoirs because of their inherent poor salt tolerance and weak thermal stability. Hydrophobic association of partially hydrolyzed polyacryamide (HAHPAM complexed with silica nanoparticles to prepare nano-hybrids is reported in this work. The rheological and enhanced oil recovery (EOR properties of such hybrids were studied in comparison with HAHPAM under simulated high-temperature and high-salinity oil reservoir conditions (T: 85 °C; total dissolved solids: 32,868 mg∙L−1; [Ca2+] + [Mg2+]: 873 mg∙L−1. It was found that the apparent viscosity and elastic modulus of HAHPAM solutions increased with addition of silica nanoparticles, and HAHPAM/silica hybrids exhibit better shear resistance and long-term thermal stability than HAHPAM in synthetic brine. Moreover, core flooding tests show that HAHPAM/silica hybrid has a higher oil recovery factor than HAHPAM solution.

  12. Analysis of Plasma Homocysteine Levels in Patients with Unstable Angina

    José Roberto Tavares

    2002-08-01

    Full Text Available OBJECTIVE - To determine the prevalence of hyperhomocystinemia in patients with acute ischemic syndrome of the unstable angina type. METHODS - We prospectively studied 46 patients (24 females with unstable angina and 46 control patients (19 males, paired by sex and age, blinded to the laboratory data. Details of diets, smoking habits, medication used, body mass index, and the presence of hypertension and diabetes were recorded, as were plasma lipid and glucose levels, C-reactive protein, and lipoperoxidation in all participants. Patients with renal disease were excluded. Plasma homocysteine was estimated using high-pressure liquid chromatography. RESULTS - Plasma homocysteine levels were significantly higher in the group of patients with unstable angina (12.7±6.7 µmol/L than in the control group (8.7±4.4 µmol/L (p<0.05. Among males, homocystinemia was higher in the group with unstable angina than in the control group, but this difference was not statistically significant (14.1±5.9 µmol/L versus 11.9±4.2 µmol/L. Among females, however, a statistically significant difference was observed between the 2 groups: 11.0±7.4 µmol/L versus 6.4±2.9 µmol/L (p<0.05 in the unstable angina and control groups, respectively. Approximately 24% of the patients had unstable angina at homocysteine levels above 15 µmol/L. CONCLUSION - High homocysteine levels seem to be a relevant prevalent factor in the population with unstable angina, particularly among females.

  13. Is the compactified vacuum semiclassically unstable

    Maeda, K.

    1987-01-01

    It is shown, by applying the positive-energy theorem, that the present vacuum (M 4 xK D ) in some higher-dimensional theories (e.g. the Candelas-Weinberg model) is stable against decay by quantum tunnelling without change of topology. Frieman and Kolb have found a quantum tunnelling instability of the present vacuum in the same models. But they did not take into account the gravitational effect, which is important and prevents the universe from decaying into the higher-dimensional de Sitter phase. (orig.)

  14. Prognostic factors for survival of women with unstable spinal bone metastases from breast cancer

    Foerster, Robert; Bruckner, Thomas; Bostel, Tilman; Schlampp, Ingmar; Debus, Juergen; Rief, Harald

    2015-01-01

    Bone metastases are an important clinical issue in women with breast cancer. Particularly, unstable spinal bone metastases (SBM) are a major cause of severe morbidity and reduced quality of life (QoL) due to frequent immobilization. Radiotherapy (RT) is the major treatment modality and is capable of promoting re-ossification and improving stability. Since local therapy response is excellent, survival of these patients with unstable SBM is of high clinical importance. We therefore conducted this analysis to assess survival and to determine prognostic factors for bone survival (BS) in women with breast cancer and unstable SBM. A total population of 92 women with unstable SBM from breast cancer who were treated with RT at our department between January 2000 and January 2012 was retrospectively investigated. We calculated overall survival (OS) and BS (time between first diagnosis of bone metastases until death) with the Kaplan-Meier method and assessed prognostic factors for BS with a Cox regression model. Mean age at first diagnosis of breast cancer was 60.8 years ± SD 12.4 years. OS after 1, 2 and 5 years was 84.8, 66.3 and 50 %, respectively. BS after 1, 2 and 5 years was 62.0, 33.7 and 12 %, respectively. An age > 50 years (p < .001; HR 1.036 [CI 1.015–1.057]), the presence of a single bone metastasis (p = .002; HR 0.469 [CI 0.292–0.753]) and triple negative phenotype (p < .001; HR 1.068 [CI 0.933–1.125]) were identified as independent prognostic factors for BS. Our analysis demonstrated a short survival of women with breast cancer and unstable SBM. Age, presence of a solitary SBM and triple-negative phenotype correlated with survival. Our results may have an impact on therapeutic decisions in the future and offer a rationale for future prospective investigations

  15. Unstable genes unstable mind: beyond the central dogma of molecular biology.

    Hegde, Mahabaleshwar V; Saraph, Arundhati A

    2011-08-01

    Schizophrenia has a polygenic mode of inheritance and an estimated heritability of over 80%, but success in understanding its genetic underpinnings to date has been modest. Unlike in trinucleotide neurodegenerative disorders, the phenomenon of genetic anticipation observed in schizophrenia or bipolar disorder has not been explained. For the first time, we provide a plausible molecular explanation of genetic anticipation and pathophysiology of schizophrenia, at least in part, with supporting evidence. We postulate that abnormally increased numbers of CAG repeats in many genes being expressed in the brain, coding for glutamine, cumulatively press for higher demand of glutamine in the respective brain cells, resulting in a metabolic crisis and dysregulation of the glutamate-glutamine cycle. This can adversely affect the functioning of both glutamate and GABA receptors, which are known to be involved in psychosis, and may also affect glutathione levels, increasing oxidative stress. The resulting psychosis (gain in function), originating from unstable genes, is described as an effect "beyond the central dogma of molecular biology". The hypothesis explains genetic anticipation, as further expansions in subsequent generations may result in increased severity and earlier occurrence. Many other well described findings provide proof of concept. This is a testable hypothesis, does not deny any known facts and opens up new avenues of research. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Unstable Resonator Mid-Infrared Laser Sources

    2016-02-26

    effective refractive indices of the guided mode at the grating ridge and groove were calcu- lated using a 4-layer slab waveguide model with a top clad... waterfall plot of the spectra. This DFB laser device demonstrated a continuous, mode-hop-free, tuning range of 80 nm, from 3057 to 3137 nm at ~2.5...curve is a quadratic fit. The inset shows the grating normal pump configuration (GNC). (b) Waterfall plot of the individual spectra vs. pump position

  17. Unstable ductile fracture conditions in upper shelf region

    Nakano, Yoshifumi; Kubo, Takahiro

    1985-01-01

    The phenomenon of unstability of ductile fracture in the upper shelf region of a forged steel for nuclear reactor pressure vessels A508 Cl. 3 was studied with a large compliance apparatus, whose spring constants were 100, 170 and 230 kgf/mm, at the test temperatures of 100, 200 and 300 0 C and at the loading rates of 2, 20 and 200 mm/min in the crosshead speed. The main results obtained are as follows: (1) The fracture modes of the specimens consisted of (a) stable fracture, (b) unstable fracture which leads to a complete fracture rapidly and (c) quasiunstable fracture which does not lead to a complete fracture though a rapid extension of ductile crack takes place. (2) Side groove, high temperature or small spring constant made a ductile crack more unstable. (3) High temperature or large spring constant made the occurrence of quasiunstable fracture easier. (4) Quasiunstable ductile fracture took place before the maximum load, that is, at the J integral value of about 10 kgf/mm. The initiation of a microscopic ductile crack, therefore, seems to lead to quasiunstable fracture. (5) The concept that unstable ductile fracture takes place when Tsub(app) exceeds Tsub(mat) seems applicable only to the case in which unstable ductile fracture takes place after the maximum load has been exceeded. (author)

  18. Cold or hot, stable or unstable collective nuclear motion

    Chomaz, Ph.; Lacroix, D.; Jacquot, B.; Colonna, M.; Ayik, S.

    1999-01-01

    We present a general discussion of the mean field dynamics of finite nuclei prepared under extreme of temperature and pressure. Many features of the dynamics are carefully studied such as the collective expansion, the evaporation process, the different time-scale. We show that under the thermal pressure and the effect of the compression, the system may reach low density regions where it may become unstable. Early development of the instabilities in a dilute nuclear source in investigated using a finite temperature quantal Rpa approach for different systems. The growth rates of the unstable collective modes are determining by solving a dispersion relation. Which is obtained by parameterizing the transition density in terms of its multipole moments. Under typical conditions of a dilute finite system at moderate temperatures the dispersion relation exhibits an ultraviolet cut-off. As a result, only a finite number of multiple modes becomes unstable , and the number of the unstable collective modes increases with the size of the source. Calculations indicate that for an expanding source, unstable modes show a transition from surface to volume character. (author)

  19. Robustness of unstable attractors in arbitrarily sized pulse-coupled networks with delay

    Broer, Henk; Efstathiou, Konstantinos; Subramanian, Easwar

    2008-01-01

    We consider arbitrarily large networks of pulse-coupled oscillators with non-zero delay where the coupling is given by the Mirollo–Strogatz function. We prove that such systems have unstable attractors (saddle periodic orbits whose stable set has non-empty interior) in an open parameter region for three or more oscillators. The evolution operator of the system can be discontinuous and we propose an improved model with continuous evolution operator

  20. Nonlinearity from quantum mechanics: Dynamically unstable Bose-Einstein condensate in a double-well trap

    Javanainen, Juha

    2010-01-01

    We study theoretically an atomic Bose-Einstein condensate in a double-well trap, both quantum-mechanically and classically, under conditions such that in the classical model an unstable equilibrium dissolves into large-scale oscillations of the atoms between the potential wells. Quantum mechanics alone does not exhibit such nonlinear dynamics, but measurements of the atom numbers in the potential wells may nevertheless cause the condensate to behave essentially classically.

  1. Numerical detection of unstable periodic orbits in continuous-time dynamical systems with chaotic behaviors

    Y. Saiki

    2007-09-01

    Full Text Available An infinite number of unstable periodic orbits (UPOs are embedded in a chaotic system which models some complex phenomenon. Several algorithms which extract UPOs numerically from continuous-time chaotic systems have been proposed. In this article the damped Newton-Raphson-Mees algorithm is reviewed, and some important techniques and remarks concerning the practical numerical computations are exemplified by employing the Lorenz system.

  2. Symmetry energy, unstable nuclei and neutron star crusts

    Iida, Kei [Kochi University, Department of Natural Science, Kochi (Japan); RIKEN Nishina Center, Saitama (Japan); Oyamatsu, Kazuhiro [RIKEN Nishina Center, Saitama (Japan); Aichi Shukutoku University, Department of Human Informatics, Aichi (Japan)

    2014-02-15

    The phenomenological approach to inhomogeneous nuclear matter is useful to describe fundamental properties of atomic nuclei and neutron star crusts in terms of the equation of state of uniform nuclear matter. We review a series of researches that we have developed by following this approach. We start with more than 200 equations of state that are consistent with empirical masses and charge radii of stable nuclei and then apply them to describe matter radii and masses of unstable nuclei, proton elastic scattering and total reaction cross sections off unstable nuclei, and nuclei in neutron star crusts including nuclear pasta. We finally discuss the possibility of constraining the density dependence of the symmetry energy from experiments on unstable nuclei and even observations of quasi-periodic oscillations in giant flares of soft gamma-ray repeaters. (orig.)

  3. On the representations of Poincare group associated with unstable particles

    Exner, RP.

    1983-01-01

    The problem of relativistically-covariant description of unstable particles is reexamined. We follow the approach which associates a unitary reducible representation of Poincare group with a larger isolated system, and compare it with the one ascribing a non-unitary irreducible representation to the unstable particle alone. It is shown that the problem roots in choice of the subspace Hsub(u) of the state Hilbert space which could be related to the unstable particle. Translational invariance of Hsub(u) is proved to be incompatible with unitarity of the boosts. Further we propose a concrete choice of Hsub(u) and argue that in most cases of the actual experimental arrangements, this subspace is effectively one-dimensional. A correct slow-down for decay of a moving particle is obtained

  4. Relevant signs of stable and unstable thoracolumbar vertebral column trauma

    Gehweiler, J.A.; Daffner, R.H.; Osborne, R.L.

    1981-01-01

    One-hundred and seventeen patients with acute thoracolumbar vertebral column fracture or fracture-dislocations were analyzed and classified into stable (36%) and unstable (64%). Eight helpful roentgen signs were observed that may serve to direct attention to serious underlying, often occult, fractures and dislocations. The changes fall into four principal groups: abnormal soft tissues, abnormal vertebral alignment, abnormal joints, and widened vertebral canal. All stable and unstable lesions showed abnormal soft tissues, while 70% demonstrated kyphosis and/or scoliosis, and an abnormal adjacent intervertebral disk space. All unstable lesions showed one or more of the following signs: displaced vertebra, widened interspinous space, abnormal apophyseal joint(s), and widened vertebral canal. (orig.)

  5. Estimation scheme for unstable ductile fracture of pressure vessel

    Takahashi, Jun; Okamura, Hiroyuki; Sakai, Shinsuke

    1990-01-01

    This paper presents a new scheme for the estimation of unstable ductile fracture using the J-integral. The proposed method uses a load-versus-displacement diagram which is generated using fully plastic solutions. By this method, the phenomena of the ductile fracture can be grasped visually. Thus, the parametrical survey can be executed far more easily than before. Then, using the proposed method, unstable ductile fracture is analyzed for single-edge cracked plates under both uniform tension and pure bending. In addition, several parametrical surveys are performed concerning (1) J-controlled crack growth, (2) compliance of the structure, (3) ductility of the material (i.e., J-resistance curve), and (4) scale of the structure (i.e., screening criterion). As a result, it is shown that the proposed method is especially effective for the paramtrical study of unstable ductile fracture. (author)

  6. Significance of Tc-99m pyrophosphate accumulation in unstable angina

    Tange, Shoichi; Kondo, Chisato; Ohta, Yoshiko; Kusakabe, Kiyoko; Shigeta, Akiko; Uchida, Tatsuro; Sumiyoshi, Tetsuya; Kaneko, Noboru; Hosoda, Saichi

    1993-01-01

    Tc-99m pyrophosphate (PYP) and Tl-201 simultaneous dual energy single photon emission computed tomography (SPECT) were performed in 33 patients with clinically unstable angina. According to the presence or absence of PYP accumulation in the myocardium, the patients were classified as PYP (+) group (n=22) and PYP (-) group (n=11). Clinical features, types of unstable angina, ECG changes, and serial creatine kinase (CK) data were compared in the two groups. The 'new angina at rest' type of unstable angina was more significantly common in the PYP (+) group (16/22) than the PYP (-) group (2/11). The remaining 6 patients in the PYP (+) group and 2 patients in the PYP (-) group had 'angina of effort with changing pattern'. There was a significant difference in the occurrence of ST elevation and ST depression between the group: 59% in the PYP (+) group vs. 18% in the PYP (-) group for ST elevation and 23% in the PYP (+) group vs. 64% in the PYP (-) group for ST depression. The PYP (+) group showed significant improvement in ejection fraction in the stable state (57±12%) as compared with the unstable state (62±11%), although there was no difference between the stable and unstable state in the PYP (-) group. Although wall motion abnormality index (WMI) was poorer in the PYP (+) group than the PYP (-) group, it improved to the same degree as the PYP (-) group one month later. These data suggest that the area showing PYP (+) may reflect stunned myocardium and that Tc-99m PYP accumulation may correlate with clinical features of unstable angina. (N.K.)

  7. Technetium-99m-pyrophosphate myocardial imaging in unstable angina

    Willerson, J.T.; Parkey, R.W.; Lewis, S.E.; Buja, L.M.; Bonte, F.J.

    1980-01-01

    The authors have found that approximately one third of patients with the syndrome of unstable angina pectoris have abnormal 99mTc-pyrophosphate myocardial scintigrams even in the absence of abnormal enzymes and electrocardiographic confirmation of the presence of acute myocardial necrosis. Thus, 99mTc-pyrophosphate myocardial imaging technique appears to represent a sensitive means to detect acute multicellular injury associated with the clinical syndrome of unstable angina pectoris even when cardiac enzymes are normal and the electrocardiogram does not definitively document the presence of acute myocardial necrosis. (Auth.)

  8. Nuclear structure and magnetic moment of the unstable 12B-12N mirror pair

    Zheng Yongnan; Zhou Dongmei; Yuan Daqing; Zuo Yi; Fan Ping; Xu Yongjun; Zhu Jiazheng; Wang Zhiqiang; Luo Hailong; Zhang Xizhen; Zhu Shengyun; Mihara, M.; Matsuta, K.; Fukuda, M.; Minamisono, T.; Suzuki, T.

    2010-01-01

    Magnetic moments of the A=12 unstable mirror pair nuclides 12 B and 12 N have been measured by the β-NMR technique. The experimentally measured magnetic moments are μ( 12 B)=1.00(17)μ N and μ( 12 N)=0.4571(1)μ N . The improved shell model using an SFO Hamiltonian with enhanced spin-isospin monopole proton-neutron interaction and modified single-particle energies is employed to calculate the magnetic moments of 12 B and 12 N. The calculation yields μ( 12 B)=0.929μ N and μ( 12 N)=0.452μ N and has produced a new magic number 6 for the short-lived unstable mirror pair nuclides 12 B and 12 N. (authors)

  9. Turbulent transport of passive scalar behind line sources in an unstably stratified open channel flow

    Liu, Chun-Ho [The Hong Kong Polytechnic University, Kowloon (Hong Kong). Department of Building and Real Estate; Leung, Dennis Y.C. [The University of Hong Kong (Hong Kong). Department of Mechanical Engineering

    2006-11-15

    This study employs a direct numerical simulation (DNS) technique to study the flow, turbulence structure, and passive scalar plume transport behind line sources in an unstably stratified open channel flow. The scalar transport behaviors for five emission heights (z{sub s}=0, 0.25H, 0.5H, 0.75H, and H, where H is the channel height) at a Reynolds number of 3000, a Prandtl number and a Schmidt number of 0.72, and a Richardson number of -0.2 are investigated. The vertically meandering mean plume heights and dispersion coefficients calculated by the current DNS model agree well with laboratory results and field measurements in literature. It is found that the plume meandering is due to the movement of the positive and negative vertical turbulent scalar fluxes above and below the mean plume heights, respectively. These findings help explaining the plume meandering mechanism in the unstably stratified atmospheric boundary layer. (author)

  10. Does Unstable Employment Have an Association with Suicide Rates among the Young?

    Kim, Chungah; Cho, Youngtae

    2017-04-28

    Although a growing body of literature has indicated that unemployment has a positive association with suicide, the dynamic aspects of unstable employment have not yet been considered in suicidology. This study explored the association between employment stability and completed suicide among people aged 25-34 years in 20 OECD (Organization for Economic Cooperation and Development) countries with time-series data (1994-2010). In order to consider the different aspects of unstable employment, we tested the impacts of employment protection legislation indicators as another proxy of job insecurity (employed, but unstable) apart from unemployment rates. Covariates, including economic growth rates, GDP per capita, fertility rates, and divorce rate, were controlled for. The analysis was designed to be gender- and age-specific, where observations with ages of 25-29 were separated from those with ages of 30-34. Random effect models were applied to examine changes over time in suicide rates, and other models were presented to check robustness. The results showed that it is a low level of employment protection, rather than unemployment itself, that was associated with increased suicide rates among all of the studied populations. The magnitude of the effect differed by gender.

  11. Effects of unstable shoes on chronic low back pain in health professionals: a randomized controlled trial.

    Armand, Stéphane; Tavcar, Ziva; Turcot, Katia; Allet, Lara; Hoffmeyer, Pierre; Genevay, Stéphane

    2014-12-01

    The aim of this study was to evaluate the effectiveness of unstable shoes in reducing low back pain in health professionals. Of a volunteer sample of 144 participants, 40 with nonspecific chronic low back pain were eligible and enrolled in this study. Participants were randomized to an intervention group, who wore unstable shoes (model MBT Fora), or a control group, who wore conventional sports shoes (model Adidas Bigroar). The participants had to wear the study shoes during their work hours, and at least 6 hours per workday, over a period of 6 weeks. The primary outcome was low back pain assessed on a Visual Analog Scale. The secondary outcomes were patient satisfaction, disability evaluated using Roland-Morris questionnaire and quality of life evaluated using EQ-VAS. The intervention group showed a significant decrease in pain scores compared to the control group. The rate of satisfaction was higher in the intervention group (79%) compared to the control group (25%). There was no significant difference for the Roland-Morris disability questionnaire score and the EQ-VAS scale. The results of this clinical trial suggest that wearing unstable shoes for 6 weeks significantly decreases low back pain in patients suffering from chronic low back pain but had no significant effect on quality of life and disability scores. Copyright © 2014 Société française de rhumatologie. Published by Elsevier SAS. All rights reserved.

  12. Neuromuscular adjustments of gait associated with unstable conditions

    Ivanenko, Y. P.; d'Avella, A.; Serrao, M.; Ranavolo, A.; Draicchio, F.; Cappellini, G.; Casali, C.; Lacquaniti, F.

    2015-01-01

    A compact description of coordinated muscle activity is provided by the factorization of electromyographic (EMG) signals. With the use of this approach, it has consistently been shown that multimuscle activity during human locomotion can be accounted for by four to five modules, each one comprised of a basic pattern timed at a different phase of gait cycle and the weighting coefficients of synergistic muscle activations. These modules are flexible, in so far as the timing of patterns and the amplitude of weightings can change as a function of gait speed and mode. Here we consider the adjustments of the locomotor modules related to unstable walking conditions. We compared three different conditions, i.e., locomotion of healthy subjects on slippery ground (SL) and on narrow beam (NB) and of cerebellar ataxic (CA) patients on normal ground. Motor modules were computed from the EMG signals of 12 muscles of the right lower limb using non-negative matrix factorization. The unstable gait of SL, NB, and CA showed significant changes compared with controls in the stride length, stride width, range of angular motion, and trunk oscillations. In most subjects of all three unstable conditions, >70% of the overall variation of EMG waveforms was accounted for by four modules that were characterized by a widening of muscle activity patterns. This suggests that the nervous system adopts the strategy of prolonging the duration of basic muscle activity patterns to cope with unstable conditions resulting from either slippery ground, reduced support surface, or pathology. PMID:26378199

  13. Wear Behavior of an Unstable Knee: Stabilization via Implant Design?

    Jörn Reinders

    2014-01-01

    Full Text Available Background. Wear-related failures and instabilities are frequent failure mechanisms of total knee replacements. High-conforming designs may provide additional stability for the joint. This study analyzes the effects of a ligamentous insufficiency on the stability and the wear behavior of a high-conforming knee design. Methods. Two simulator wear tests were performed on a high-conforming total knee replacement design. In the first, a ligamentous-stable knee replacement with a sacrificed anterior cruciate ligament was simulated. In the second, a ligamentous-unstable knee with additionally insufficient posterior cruciate ligament and medial collateral ligament was simulated. Wear was determined gravimetrically and wear particles were analyzed. Implant kinematics was recorded during simulation. Results. Significantly higher wear rates (P≤0.001 were observed for the unstable knee (14.58±0.56 mg/106 cycles compared to the stable knee (7.97 ± 0.87 mg/106 cycles. A higher number of wear particles with only small differences in wear particle characteristics were observed. Under unstable knee conditions, kinematics increased significantly for translations and rotations (P≤0.01. This increase was mainly attributed to higher tibial posterior translation and internal rotations. Conclusion. Higher kinematics under unstable test conditions is a result of insufficient stabilization via implant design. Due to the higher kinematics, increased wear was observed in this study.

  14. On Debye radius measurement in an unstable gas discharged plasma

    Shvilkin, B.N.

    1998-01-01

    It is shown that at low concentrations of charged particles conditions can be realized in a magnetized unstable-to-drift plasma for which concentration perturbations are comparable to the concentration itself. The electron temperature is then determined by potential fluctuations, and the drift oscillation wavelength is of the order of the Debye length

  15. Unstable oscillatory Pierce modes of neutralized electron beams

    Cary, J.R.; Lemons, D.S.

    1982-01-01

    Oscillatory modes of the Pierce system have been calculated. These modes are found to have growth rates comparable to the previously investigated purely growing modes. When these modes are included, it is found that the Pierce system is unstable for most values of ω/sub p/ L/V 0 >π

  16. Thallium-201 myocardial imaging in unstable angina and variant angina

    Wackers, F.J.Th.; Lie, K.I.; Liem, K.L.; Sokole, E.B.; Schoot, J.B. van der

    1980-01-01

    It is of clinical relevance in the coronary care unit to evaluate the potential role of 201 Tl scintigraphy in patients with unstable angina. In the present chapter the authors discuss 1) the pattern of 201 Tl scintigraphy in patients with unstable angina; and 2) the potential predictive value of 201 Tl scintigraphy in identifying patients with unstable angina who have a poorer prognosis or greater tendency to subsequently develop acute myocardial infarction. All patients with unstable angina pectoris were purposely studied during the pain free period. It seemed conceivable that injecting 201 Tl during an anginal attack would result in a high percentage of scintigraphic defects and probably diminish a potential discriminative value of the method. Moreover in clinical practice the majority of patients arrive at the coronary care unit some time after the last anginal attack. If a diagnostic test performed at this time could distinguish high and low risk patients, important therapeutic decisions might be made at the earliest possible times. (Auth.)

  17. Stimulation of confocal unstable resonators using thin gain sheet

    Du Yanyi

    2000-01-01

    Mode calculation in unstable resonators with flowing saturable gain using the fast Fourier transform (FFT) algorithm and thin gain sheet just nearly inside the big mirror. This method is in resonators of small disturbance (ψ 0max = π/2), middle magnification (m 0 ∼= 1%)

  18. Subphotospheric fluctuations in magnetized radiative envelopes: contribution from unstable magnetosonic waves

    Sen, Koushik; Fernández, Rodrigo; Socrates, Aristotle

    2018-06-01

    We examine the excitation of unstable magnetosonic waves in the radiative envelopes of intermediate- and high-mass stars with a magnetic field of ˜kG strength. Wind clumping close to the star and microturbulence can often be accounted for when including small-scale, subphotospheric density or velocity perturbations. Compressional waves - with wavelengths comparable to or shorter than the gas pressure scale height - can be destabilized by the radiative flux in optically thick media when a magnetic field is present, in a process called the radiation-driven magneto-acoustic instability (RMI). The instability does not require radiation or magnetic pressure to dominate over gas pressure, and acts independently of subsurface convection zones. Here we evaluate the conditions for the RMI to operate on a grid of stellar models covering a mass range 3-40 M⊙ at solar metallicity. For a uniform 1 kG magnetic field, fast magnetosonic modes are unstable down to an optical depth of a few tens, while unstable slow modes extend beyond the depth of the iron convection zone. The qualitative behaviour is robust to magnetic field strength variations by a factor of a few. When combining our findings with previous results for the saturation amplitude of the RMI, we predict velocity fluctuations in the range ˜0.1-10 km s-1. These amplitudes are a monotonically increasing function of the ratio of radiation to gas pressure, or alternatively, of the zero-age main sequence mass.

  19. Genesis and bifurcations of unstable periodic orbits in a jet flow

    Uleysky, M Yu; Budyansky, M V; Prants, S V

    2008-01-01

    We study the origin and bifurcations of typical classes of unstable periodic orbits in a jet flow that was introduced before as a kinematic model of chaotic advection, transport and mixing of passive scalars in meandering oceanic and atmospheric currents. A method to detect and locate the unstable periodic orbits and classify them by the origin and bifurcations is developed. We consider in detail period-1 and period-4 orbits playing an important role in chaotic advection. We introduce five classes of period-4 orbits: western and eastern ballistic ones, whose origin is associated with ballistic resonances of the fourth-order, rotational ones, associated with rotational resonances of the second and fourth orders and rotational-ballistic ones associated with a rotational-ballistic resonance. It is a new kind of unstable periodic orbits that may appear in a chaotic flow with jets and/or circulation cells. Varying the perturbation amplitude, we track out the origin and bifurcations of the orbits for each class

  20. Emission temperatures from the decay of particle-unstable complex nuclei

    Nayak, T.K.

    1990-01-01

    Relative populations of particle-unstable states were measured for complex fragments emitted in the reaction 14 N + Ag at E/A = 35 MeV by using a position sensitive high resolution hodoscope. Experimental population probabilities of particle-unstable states were extracted by fitting the coincidence spectra of the decay products by an appropriate R-matrix or Breit-Wigner formalism. According to thermal models, the populations of excited states at freezeout are expected to follow a Boltzmann distribution weighted by the emission temperature of the system. Tests of this freezeout assumption were made by comparing the experimental population to the predictions of statistical calculations. Extensive statistical calculation which include the effect of sequential feeding from heavier particle unstable nuclei were performed to estimate the population probabilities and the ratios of population probabilities indicate emission temperatures of about 3-4 MeV. But a detailed comparison for individual fragments for a calculation with T em = 4 MeV reveals that about half of the measured population probabilities and one third of the ratios of the population probabilities differ significantly from the predictions of statistical calculations. Calculations which include rotational effects could not satisfactorily account for this discrepancy. These results suggest a possible breakdown of the assumption of local thermal equilibrium at freezeout

  1. GPU-based simulation of the two-dimensional unstable structure of gaseous oblique detonations

    Teng, H.H.; Kiyanda, C.B.; Ng, H.D. [Department of Mechanical and Industrial Engineering, Concordia University, Montréal, QC, H3G 1M8 (Canada); Morgan, G.H.; Nikiforakis, N. [Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE (United Kingdom)

    2015-03-10

    In this paper, the two-dimensional structure of unstable oblique detonations induced by the wedge from a supersonic combustible gas flow is simulated using the reactive Euler equations with a one-step Arrhenius chemistry model. A wide range of activation energy of the combustible mixture is considered. Computations are performed on the Graphical Processing Unit (GPU) to reduce the simulation runtimes. A large computational domain covered by a uniform mesh with high grid resolution is used to properly capture the development of instabilities and the formation of different transverse wave structures. After the initiation point, where the oblique shock transits into a detonation, an instability begins to manifest and in all cases, the left-running transverse waves first appear, followed by the subsequent emergence of right-running transverse waves forming the dual-head triple point structure. This study shows that for low activation energies, a long computational length must be carefully considered to reveal the unstable surface due to the slow growth rate of the instability. For high activation energies, the flow behind the unstable oblique detonation features the formation of unburnt gas pockets and strong vortex-pressure wave interaction resulting in a chaotic-like vortical structure.

  2. Research of Medical Expenditure among Inpatients with Unstable Angina Pectoris in a Single Center.

    Wu, Suo-Wei; Pan, Qi; Chen, Tong; Wei, Liang-Yu; Xuan, Yong; Wang, Qin; Li, Chao; Song, Jing-Chen

    2017-07-05

    With the rising incidence as well as the medical expenditure among patients with unstable angina pectoris, the research aimed to investigate the inpatient medical expenditure through the combination of diagnosis-related groups (DRGs) among patients with unstable angina pectoris in a Grade A tertiary hospital to conduct the referential standards of medical costs for the diagnosis. Single-factor analysis and multiple linear stepwise regression method were used to investigate 3933 cases between 2014 and 2016 in Beijing Hospital (China) whose main diagnosis was defined as unstable angina pectoris to determine the main factors influencing the inpatient medical expenditure, and decision tree method was adopted to establish the model of DRGs grouping combinations. The major influential factors of inpatient medical expenditure included age, operative method, therapeutic effects as well as comorbidity and complications (CCs) of the disease, and the 3933 cases were divided into ten DRGs by four factors: age, CCs, therapeutic effects, and the type of surgery with corresponding inpatient medical expenditure standards setup. Data of nonparametric test on medical costs among different groups were all significant (P angina pectoris is conducive in standardizing the diagnosis and treatment behaviors of the hospital and reducing economic burdens among patients.

  3. Market potential of solar thermal enhanced oil recovery-a techno-economic model for Issaran oil field in Egypt

    Gupta, Sunay; Guédez, Rafael; Laumert, Björn

    2017-06-01

    Solar thermal enhanced oil recovery (S-EOR) is an advanced technique of using concentrated solar power (CSP) technology to generate steam and recover oil from maturing oil reservoirs. The generated steam is injected at high pressure and temperature into the reservoir wells to facilitate oil production. There are three common methods of steam injection in enhanced oil recovery - continuous steam injection, cyclic steam stimulation (CSS) and steam assisted gravity drainage (SAGD). Conventionally, this steam is generated through natural gas (NG) fired boilers with associated greenhouse gas emissions. However, pilot projects in the USA (Coalinga, California) and Oman (Miraah, Amal) demonstrated the use of S-EOR to meet their steam requirements despite the intermittent nature of solar irradiation. Hence, conventional steam based EOR projects under the Sunbelt region can benefit from S-EOR with reduced operational expenditure (OPEX) and increased profitability in the long term, even with the initial investment required for solar equipment. S-EOR can be realized as an opportunity for countries not owning any natural gas resources to make them less energy dependent and less sensible to gas price fluctuations, and for countries owning natural gas resources to reduce their gas consumption and export it for a higher margin. In this study, firstly, the market potential of S-EOR was investigated worldwide by covering some of the major ongoing steam based EOR projects as well as future projects in pipeline. A multi-criteria analysis was performed to compare local conditions and requirements of all the oil fields based on a defined set of parameters. Secondly, a modelling approach for S-EOR was designed to identify cost reduction opportunities and optimum solar integration techniques, and the Issaran oil field in Egypt was selected for a case study to substantiate the approach. This modelling approach can be consulted to develop S-EOR projects for any steam flooding based oil

  4. Trunk muscle activity increases with unstable squat movements.

    Anderson, Kenneth; Behm, David G

    2005-02-01

    The objective of this study was to determine differences in electromyographic (EMG) activity of the soleus (SOL), vastus lateralis (VL), biceps femoris (BF), abdominal stabilizers (AS), upper lumbar erector spinae (ULES), and lumbo-sacral erector spinae (LSES) muscles while performing squats of varied stability and resistance. Stability was altered by doing the squat movement on a Smith machine, a free squat, and while standing on two balance discs. Fourteen male subjects performed the movements. Activities of the SOL, AS, ULES, and LSES were highest during the unstable squat and lowest with the Smith machine protocol (p squats on unstable surfaces may permit a training adaptation of the trunk muscles responsible for supporting the spinal column (i.e., erector spinae) as well as the muscles most responsible for maintaining posture (i.e., SOL).

  5. Non-Abelian magnetized blackholes and unstable attractors

    Mosaffa, A.E.; Randjbar-Daemi, S.; Sheikh-Jabbari, M.M.

    2006-12-01

    Fluctuations of non-Abelian gauge fields in a background magnetic flux contain tachyonic modes and hence the background is unstable. We extend these results to the cases where the background flux is coupled to Einstein gravity and show that the corresponding spherically symmetric geometries, which in the absence of a cosmological constant are of the form of Reissner-Nordstroem blackholes or the AdS 2 x S 2 , are also unstable. We discuss the relevance of these instabilities to several places in string theory including various string compactifications and the attractor mechanism. Our results for the latter imply that the attractor mechanism shown to work for the extremal Abelian charged blackholes, cannot be applied in a straightforward way to the extremal non-Abelian colored blackholes. (author)

  6. Stabilization of switched nonlinear systems with unstable modes

    Yang, Hao; Cocquempot, Vincent

    2014-01-01

    This book provides its reader with a good understanding of the stabilization of switched nonlinear systems (SNS), systems that are of practical use in diverse situations: design of fault-tolerant systems in space- and aircraft; traffic control; and heat propagation control of semiconductor power chips. The practical background is emphasized throughout the book; interesting practical examples frequently illustrate the theoretical results with aircraft and spacecraft given particular prominence. Stabilization of Switched Nonlinear Systems with Unstable Modes treats several different subclasses of SNS according to the characteristics of the individual system (time-varying and distributed parameters, for example), the state composition of individual modes and the degree and distribution of instability in its various modes. Achievement and maintenance of stability across the system as a whole is bolstered by trading off between individual modes which may be either stable or unstable, or by exploiting areas of part...

  7. Spinal instrumentation for unstable C1-2 injury.

    Mizuno, J; Nakagawa, H

    1999-06-01

    Seventeen patients with unstable C1-2 injuries were treated between 1990 and 1997. Various methods of instrumentation surgery were performed in 16 patients, excluding a case of atlantoaxial rotatory fixation. Posterior stabilization was carried out in 14 cases using Halifax interlaminar clamp, Sof'wire or Danek cable, or more recently, transarticular screws. Transodontoid anterior screw fixation was performed in four cases of odontoid process fractures, with posterior instrumentation in two cases because of malunion. Rigid internal fixation by instrumentation surgery for the unstable C1-2 injury avoids long-term application of a Halo brace and facilitates early rehabilitation. However, the procedure is technically demanding with the risk of neural and vascular injuries, particularly with posterior screw fixation. Sagittal reconstruction of thin-sliced computed tomography scans at the C1-2 region, neuronavigator, and intraoperative fluoroscopy are essential to allow preoperative surgical planning and intraoperative guidance.

  8. Numerical simulation on beam breakup unstability of linear induction accelerator

    Zhang Kaizhi; Wang Huacen; Lin Yuzheng

    2003-01-01

    A code is written to simulate BBU in induction linac according to theoretical analysis. The general form of evolution of BBU in induction linac is investigated at first, then the effect of related parameters on BBU is analyzed, for example, the alignment error, oscillation frequency of beam centroid, beam pulse shape and acceleration gradient. At last measures are put forward to damp beam breakup unstability (BBU)

  9. Mixing phases of unstable two-level systems

    Sokolov, V.V.; Brentano, P. von.

    1993-01-01

    An unstable two-level system decaying into an arbitrary number of channels is considered. It is shown that the mixing phases of the two overlapping resonances can be expressed in the terms of their partial widths and one additional universal mixing parameter. Some applications to a doublet of 2 + resonances in 8 Be and to the ρ-ω systems are considered. 18 refs

  10. Scalar Hairy Black Holes in Four Dimensions are Unstable

    Ganchev, Bogdan; Santos, Jorge E.

    2018-04-01

    We present a numerical analysis of the stability properties of the black holes with scalar hair constructed by Herdeiro and Radu. We prove the existence of a novel gauge where the scalar field perturbations decouple from the metric perturbations, and analyze the resulting quasinormal mode spectrum. We find unstable modes with characteristic growth rates which for uniformly small hair are almost identical to those of a massive scalar field on a fixed Kerr background.

  11. Disabilities caused by unstable mutations in Costa Rica

    Morales Montero, Fernando; Cuenca Berger, Patricia; Castro Volio, Isabel

    2004-01-01

    Myotonic dystrophy and fragile X syndrome are two genetically determined relatively common disabilities. Both are examples of a new type of mutation mechanism called unstable or dynamic mutations, triple repeats expansions or DNA amplification. Fragile X syndrome is recognized as the main cause of hereditary mental retardation and myotonic dystrophy is considered the most common muscular dystrophy of adults. This is a prospective non randomized study of clinically affected people,...

  12. Renormalization, unstable manifolds, and the fractal structure of mode locking

    Cvitanovic, P.; Jensen, M.H.; Kadanoff, L.P.; Procaccia, I.

    1985-01-01

    The apparent universality of the fractal dimension of the set of quasiperiodic windings at the onset of chaos in a wide class of circle maps is described by construction of a universal one-parameter family of maps which lies along the unstable manifold of the renormalization group. The manifold generates a universal ''devil's staircase'' whose dimension agrees with direct numerical calculations. Applications to experiments are discussed

  13. Sutudy on exchange flow under the unstably stratified field

    文沢, 元雄

    2005-01-01

    This paper deals with the exchange flow under the unstably stratified field. The author developed the effective measurement system as well as the numerical analysis program. The system and the program are applied to the helium-air exchange flow in a rectangular channel with inclination. Following main features of the exchange flow were discussed based on the calculated results.(1) Time required for establishing a quasi-steady state exchange flow.(2) The relationship between the inclination an...

  14. Three-dimensional TDHF calculation for reactions of unstable nuclei

    Kim, Ka-Hae; Otsuka, Takaharu [Tokyo Univ. (Japan). Dept. of Physics; Bonche, P.

    1998-07-01

    The fusion is studied for reactions between a stable and an unstable nuclei with neutron skin. The reactions {sup 16,28}O+{sup 40}Ca and {sup 16}O+{sup 16,28}O are taken as examples, and the three-dimensional time-dependent Hartree-Fock method with the full Skyrme interaction is used. It is confirmed that the fusion cross section in low-energy region is sensitive to the interaction used in the calculation. (author)

  15. Scalar Hairy Black Holes in Four Dimensions are Unstable.

    Ganchev, Bogdan; Santos, Jorge E

    2018-04-27

    We present a numerical analysis of the stability properties of the black holes with scalar hair constructed by Herdeiro and Radu. We prove the existence of a novel gauge where the scalar field perturbations decouple from the metric perturbations, and analyze the resulting quasinormal mode spectrum. We find unstable modes with characteristic growth rates which for uniformly small hair are almost identical to those of a massive scalar field on a fixed Kerr background.

  16. Unstable states produced in collisions among complex nuclei

    Sepulveda J, D.

    1978-01-01

    A theory about resonant elastic dispersion is formulated and the wave function of unstable states associated with the resonances observed in the differential and total sections is studied. The object of this theory is to extend to the elastic collisions among complex nuclei interesting case, the methods and formalism of the dispersion of particles without structure by an external potential, following an idea originally formulated by H. Feshbach. (author)

  17. Ligament rupture and unstable burst behaviors of axial flaws in steam generator U-bends

    Bahn, Chi Bum, E-mail: bahn@pusan.ac.kr [Pusan National University, 2 Busandaehak-ro 63 beon-gil, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Oh, Young-Jin [KEPCO Engineering & Construction Co. Inc., Seongnam 463-870 (Korea, Republic of); Majumdar, Saurin [Argonne National Laboratory, Lemont, IL 60439 (United States)

    2015-11-15

    Highlights: • Ligament rupture and unstable burst pressure tests were conducted with U-bends. • In general, U-bends showed higher ligament rupture and burst pressures than straight tubes. • U-bend test data was bounded by 90% lower limit of the probabilistic models for straight tubes. • Prediction models for straight tubes could be conservatively applied to U-bends. - Abstract: Incidents of U-bend cracking in steam generator (SG) tubes have been reported, some of which have led to tube rupture. Experimental and analytical modeling efforts to determine the failure criteria of flawed SG U-bends are limited. To evaluate structural integrity of flawed U-bends, ligament rupture and unstable burst pressure tests were conducted on 57 and 152 mm bend radius U-bends with axial electrical discharge machining notches. In general, the ligament rupture and burst pressures of the U-bends were higher than those of straight tubes with similar notches. To quantitatively address the test data scatter issue, probabilistic models were introduced. All ligament rupture and burst pressures of U-bends were bounded by 90% lower limits of the probabilistic models for straight tubes. It was concluded that the prediction models for straight tubes could be applied to U-bends to conservatively evaluate the ligament rupture and burst pressures of U-bends with axial flaws.

  18. Ligament rupture and unstable burst behaviors of axial flaws in steam generator U-bends

    Bahn, Chi Bum; Oh, Young-Jin; Majumdar, Saurin

    2015-01-01

    Highlights: • Ligament rupture and unstable burst pressure tests were conducted with U-bends. • In general, U-bends showed higher ligament rupture and burst pressures than straight tubes. • U-bend test data was bounded by 90% lower limit of the probabilistic models for straight tubes. • Prediction models for straight tubes could be conservatively applied to U-bends. - Abstract: Incidents of U-bend cracking in steam generator (SG) tubes have been reported, some of which have led to tube rupture. Experimental and analytical modeling efforts to determine the failure criteria of flawed SG U-bends are limited. To evaluate structural integrity of flawed U-bends, ligament rupture and unstable burst pressure tests were conducted on 57 and 152 mm bend radius U-bends with axial electrical discharge machining notches. In general, the ligament rupture and burst pressures of the U-bends were higher than those of straight tubes with similar notches. To quantitatively address the test data scatter issue, probabilistic models were introduced. All ligament rupture and burst pressures of U-bends were bounded by 90% lower limits of the probabilistic models for straight tubes. It was concluded that the prediction models for straight tubes could be applied to U-bends to conservatively evaluate the ligament rupture and burst pressures of U-bends with axial flaws.

  19. Generating unstable resonances for extraction schemes based on transverse splitting

    M. Giovannozzi

    2009-02-01

    Full Text Available A few years ago, a novel multiturn extraction scheme was proposed, based on particle trapping inside stable resonances. Numerical simulations and experimental tests have confirmed the feasibility of such a scheme for low order resonances. While the third-order resonance is generically unstable and those higher than fourth order are generically stable, the fourth-order resonance can be either stable or unstable depending on the specifics of the system under consideration. By means of the normal form, a general approach to control the stability of the fourth-order resonance has been derived. This approach is based on the control of the amplitude detuning and the general form for a lattice with an arbitrary number of sextupole and octupole families is derived in this paper. Numerical simulations have confirmed the analytical results and have shown that, when crossing the unstable fourth-order resonance, the region around the center of the phase space is depleted and particles are trapped in only the four stable islands. A four-turn extraction could be designed using this technique.

  20. Quantum demolition filtering and optimal control of unstable systems.

    Belavkin, V P

    2012-11-28

    A brief account of the quantum information dynamics and dynamical programming methods for optimal control of quantum unstable systems is given to both open loop and feedback control schemes corresponding respectively to deterministic and stochastic semi-Markov dynamics of stable or unstable systems. For the quantum feedback control scheme, we exploit the separation theorem of filtering and control aspects as in the usual case of quantum stable systems with non-demolition observation. This allows us to start with the Belavkin quantum filtering equation generalized to demolition observations and derive the generalized Hamilton-Jacobi-Bellman equation using standard arguments of classical control theory. This is equivalent to a Hamilton-Jacobi equation with an extra linear dissipative term if the control is restricted to Hamiltonian terms in the filtering equation. An unstable controlled qubit is considered as an example throughout the development of the formalism. Finally, we discuss optimum observation strategies to obtain a pure quantum qubit state from a mixed one.

  1. Generating Unstable Resonances for Extraction Schemes Based on Transverse Splitting

    Giovannozzi, M; Turchetti, G

    2009-01-01

    A few years ago, a novel multi-turn extraction scheme was proposed, based on particle trapping inside stable resonances. Numerical simulations and experimental tests have confirmed the feasibility of such a scheme for low order resonances. While the third-order resonance is generically unstable and those higher than fourth-order are generically stable, the fourth-order resonance can be either stable or unstable depending on the specifics of the system under consideration. By means of the Normal Form a general approach to control the stability of the fourth-order resonance has been derived. This approach is based on the control of the amplitude detuning and the general form for a lattice with an arbitrary number of sextupole and octupole families is derived in this paper. Numerical simulations have confirmed the analytical results and have shown that, when crossing the unstable fourth-order resonance, the region around the centre of the phase space is depleted and particles are trapped in only the four stable ...

  2. Lyapunov vectors and assimilation in the unstable subspace: theory and applications

    Palatella, Luigi; Carrassi, Alberto; Trevisan, Anna

    2013-01-01

    Based on a limited number of noisy observations, estimation algorithms provide a complete description of the state of a system at current time. Estimation algorithms that go under the name of assimilation in the unstable subspace (AUS) exploit the nonlinear stability properties of the forecasting model in their formulation. Errors that grow due to sensitivity to initial conditions are efficiently removed by confining the analysis solution in the unstable and neutral subspace of the system, the subspace spanned by Lyapunov vectors with positive and zero exponents, while the observational noise does not disturb the system along the stable directions. The formulation of the AUS approach in the context of four-dimensional variational assimilation (4DVar-AUS) and the extended Kalman filter (EKF-AUS) and its application to chaotic models is reviewed. In both instances, the AUS algorithms are at least as efficient but simpler to implement and computationally less demanding than their original counterparts. As predicted by the theory when error dynamics is linear, the optimal subspace dimension for 4DVar-AUS is given by the number of positive and null Lyapunov exponents, while the EKF-AUS algorithm, using the same unstable and neutral subspace, recovers the solution of the full EKF algorithm, but dealing with error covariance matrices of a much smaller dimension and significantly reducing the computational burden. Examples of the application to a simplified model of the atmospheric circulation and to the optimal velocity model for traffic dynamics are given. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Lyapunov analysis: from dynamical systems theory to applications’. (paper)

  3. Long-term effects of electrical neurostimulation in patients with unstable angina : Refractory to conventional therapies

    de Vries, Jessica; DeJongste, Mike J. L.; Zijlstra, Felix; Staal, Michiel

    2007-01-01

    Background. Patients with unstable angina pectoris may become refractory to conventional therapies. Electrical neurostimulation with transcutaneous electrical stimulation and/or spinal cord stimulation has been shown to be effective for patients with refractory unstable angina pectoris in hospital

  4. Appearance of Unstable Monopoly State Caused by Selective and Concentrative Mergers in Business Networks.

    Goto, Hayato; Viegas, Eduardo; Jensen, Henrik Jeldtoft; Takayasu, Hideki; Takayasu, Misako

    2017-07-11

    Recently, growth mechanism of firms in complex business networks became new targets of scientific study owing to increasing availability of high quality business firms' data. Here, we paid attention to comprehensive data of M&A events for 40 years and derived empirical laws by applying methods and concepts of aggregation dynamics of aerosol physics. It is found that the probability of merger between bigger firms is bigger than that between smaller ones, and such tendency is enhancing year by year. We introduced a numerical model simulating the whole ecosystem of firms and showed that the system is already in an unstable monopoly state in which growth of middle sized firms are suppressed.

  5. Foam for Enhanced Oil Recovery : Modeling and Analytical Solutions

    Ashoori, E.

    2012-01-01

    Foam increases sweep in miscible- and immiscible-gas enhanced oil recovery by decreasing the mobility of gas enormously. This thesis is concerned with the simulations and analytical solutions for foam flow for the purpose of modeling foam EOR in a reservoir. For the ultimate goal of upscaling our

  6. Numerical simulation of a improving virtual confocal unstable resonator with circular mirrors of spherical surfaces

    Wang Taichun; Fu Hanqing; Du Xiangwan

    1999-01-01

    Based on the analysis of advantages and disadvantages of the unstable resonator with a phase-unifying output coupler, the improving unstable resonator are designed. The numerical simulation results indicate that the improving unstable resonator overcomes disadvantages of that resonator and its far-field intensity focusing is better than the conventional resonator

  7. Strategy switching in the stabilization of unstable dynamics.

    Jacopo Zenzeri

    Full Text Available In order to understand mechanisms of strategy switching in the stabilization of unstable dynamics, this work investigates how human subjects learn to become skilled users of an underactuated bimanual tool in an unstable environment. The tool, which consists of a mass and two hand-held non-linear springs, is affected by a saddle-like force-field. The non-linearity of the springs allows the users to determine size and orientation of the tool stiffness ellipse, by using different patterns of bimanual coordination: minimal stiffness occurs when the two spring terminals are aligned and stiffness size grows by stretching them apart. Tool parameters were set such that minimal stiffness is insufficient to provide stable equilibrium whereas asymptotic stability can be achieved with sufficient stretching, although at the expense of greater effort. As a consequence, tool users have two possible strategies for stabilizing the mass in different regions of the workspace: 1 high stiffness feedforward strategy, aiming at asymptotic stability and 2 low stiffness positional feedback strategy aiming at bounded stability. The tool was simulated by a bimanual haptic robot with direct torque control of the motors. In a previous study we analyzed the behavior of naïve users and we found that they spontaneously clustered into two groups of approximately equal size. In this study we trained subjects to become expert users of both strategies in a discrete reaching task. Then we tested generalization capabilities and mechanism of strategy-switching by means of stabilization tasks which consist of tracking moving targets in the workspace. The uniqueness of the experimental setup is that it addresses the general problem of strategy-switching in an unstable environment, suggesting that complex behaviors cannot be explained in terms of a global optimization criterion but rather require the ability to switch between different sub-optimal mechanisms.

  8. Analysis of PITFL injuries in rotationally unstable ankle fractures.

    Warner, Stephen J; Garner, Matthew R; Schottel, Patrick C; Hinds, Richard M; Loftus, Michael L; Lorich, Dean G

    2015-04-01

    Reduction and stabilization of the syndesmosis in unstable ankle fractures is important for ankle mortise congruity and restoration of normal tibiotalar contact forces. Of the syndesmotic ligaments, the posterior inferior tibiofibular ligament (PITFL) provides the most strength for maintaining syndesmotic stability, and previous work has demonstrated the significance of restoring PITFL function when it remains attached to a posterior malleolus fracture fragment. However, little is known regarding the nature of a PITFL injury in the absence of a posterior malleolus fracture. The goal of this study was to describe the PITFL injury pattern based on magnetic resonance imaging (MRI) and intraoperative observation. A prospective database of all operatively treated ankle fractures by a single surgeon was used to identify all supination-external rotation (SER) types III and IV ankle fracture patients with complete preoperative orthogonal ankle radiographs and MRI. All patients with a posterior malleolus fracture were excluded. Using a combination of preoperative imaging and intraoperative findings, we analyzed the nature of injuries to the PITFL. In total, 185 SER III and IV operatively treated ankle fractures with complete imaging were initially identified. Analysis of the preoperative imaging and operative reports revealed 34% (63/185) had a posterior malleolus fracture and were excluded. From the remaining 122 ankle fractures, the PITFL was delaminated from the posterior malleolus in 97% (119/122) of cases. A smaller proportion (3%; 3/122) had an intrasubstance PITFL rupture. Accurate and stable syndesmotic reduction is a significant component of restoring the ankle mortise after unstable ankle fractures. In our large cohort of rotationally unstable ankle fractures without posterior malleolus fractures, we found that most PITFL injuries occur as a delamination off the posterior malleolus. This predictable PITFL injury pattern may be used to guide new methods for

  9. Unstable Periodic Orbit Analysis of Histograms of Chaotic Time Series

    Zoldi, S.M.

    1998-01-01

    Using the Lorenz equations, we have investigated whether unstable periodic orbits (UPOs) associated with a strange attractor may predict the occurrence of the robust sharp peaks in histograms of some experimental chaotic time series. Histograms with sharp peaks occur for the Lorenz parameter value r=60.0 but not for r=28.0 , and the sharp peaks for r=60.0 do not correspond to a histogram derived from any single UPO. However, we show that histograms derived from the time series of a non-Axiom-A chaotic system can be accurately predicted by an escape-time weighting of UPO histograms. copyright 1998 The American Physical Society

  10. Stability of unstably stratified shear flow between parallel plates

    Fujimura, Kaoru; Kelly, R E

    1987-09-01

    The linear stability of unstably stratified shear flows between two horizontal parallel plates was investigated. Eigenvalue problems were solved numerically by making use of the expansion method in Chebyshev polynomials, and the critical Rayleigh numbers were obtained accurately in the Reynolds number range of (0.01, 100). It was found that the critical Rayleigh number increases with an increase of the Reynolds number. The result strongly supports previous stability analyses except for the analysis by Makino and Ishikawa (J. Jpn. Soc. Fluid Mech. 4 (1985) 148 - 158) in which a decrease of the critical Rayleigh number was obtained.

  11. Stability of unstably stratified shear flow between parallel plates

    Fujimura, Kaoru; Kelly, R.E.

    1987-01-01

    The linear stability of unstably stratified shear flows between two horizontal parallel plates was investigated. Eigenvalue problems were solved numerically by making use of the expansion method in Chebyshev polynomials, and the critical Rayleigh numbers were obtained accurately in the Reynolds number range of [0.01, 100]. It was found that the critical Rayleigh number increases with an increase of the Reynolds number. The result strongly supports previous stability analyses except for the analysis by Makino and Ishikawa [J. Jpn. Soc. Fluid Mech. 4 (1985) 148 - 158] in which a decrease of the critical Rayleigh number was obtained. (author)

  12. Sacral neuromodulation in the treatment of the unstable bladder.

    Bosch, J L

    1998-07-01

    Sacral neuromodulation as a treatment for urge incontinence in patients with an unstable bladder is the subject of ongoing clinical studies. Although approximately 75% of the patients treated with a permanent sacral foramen electrode implant have experienced significant improvements, it is now also clear that there is an initial failure rate of about 25%. Recent studies have pointed out the importance of improved patient selection on the basis of sex differences, urodynamic parameters and psychological factors. Also, newer forms of test stimulation and permanent electrode implantation are being explored in an effort to improve on the present results.

  13. On the definition of entropy for quantum unstable states

    Civitarese, Osvaldo; Gadella, Manuel

    2015-01-01

    The concept of entropy is central to the formulation of the quantum statistical mechanics, and it is linked to the definition of the density operator and the associated probabilities of occupation of quantum states. The extension of this scheme to accommodate for quantum decaying states is conceptually difficult, because of the nature of these states. Here we present a way to treat quantum unstable states in the context of statistical mechanics. We focuss on the definition of the entropy and avoid the use of complex temperatures

  14. Molecular Dynamics Simulation of Spontaneous Imbibition in Nanopores and Recovery of Asphaltenic Crude Oils Using Surfactants for EOR Applications Simulations de dynamique moléculaire d’imbibition spontanée dans des nanopores et pour la récupération d’huiles brutes asphalténiques en utilisant des agents tensioactifs pour des applications d’EOR

    Stukan M.R.

    2012-12-01

    Full Text Available We present Molecular Dynamics (MD simulations of the imbibition process in nanopores in case of two different mechanisms of the wettability modification. We compare the imbibition of an aqueous surfactant solution into an oil-wet pore driven by surfactant adsorption onto the oil-wet rock surface (coating mechanism and the imbibition of an aqueous surfactants solution driven by surfactants removing the contaminant molecules from the originally water-wet surface (cleaning mechanism. Our results show qualitative difference in the imbibition dynamics in these two cases and indicate that MD simulation is a useful tool to investigate details of the imbibition mechanisms at the pore scale with direct implications for Enhanced Oil Recovery (EOR operations. Nous presentons des simulations de Dynamique Moleculaire (DM du processus d’imbibition dans des nanopores dans le cas de deux mecanismes differents de modification de mouillabilite. Nous comparons l’imbibition d’une solution aqueuse d’agent tensioactif dans un pore mouille d’huile entrainee par une adsorption d’agent tensioactif sur la surface de roche mouillee d’huile (mecanisme de revetement et l’imbibition d’une solution aqueuse d’agent tensioactif entrainee par des agents tensioactifs eliminant les molecules contaminantes de la surface originellement mouillee d’eau (mecanisme de nettoyage. Nos resultats montrent une difference qualitative en matiere de dynamique d’imbibition dans ces deux cas et indiquent que la simulation de DM constitue un outil utile pour etudier les mecanismes d’imbibition a l’echelle des pores avec des implications directes pour des operations de recuperation renforcee d’huile (EOR, Enhanced Oil Recovery.

  15. Unstable roll motions by parametric resonance in following seas. Keisu reiki shindo ni motozuku oinamichu fuantei yokoyure

    Ishiguro, T.; Ito, A.; Mizoguchi, S. (Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan))

    1991-05-01

    The unstable rolling region and angle in the regular waves were studied by both tank test modeling a large container ship and theoretical calculation based on Mathieu{prime}s equation. Further research was made on the influence of metacentric height (GM) under the calm sea condition, ship speed and bilge keel dimension on the unstable rolling region. To avoid the unstable roll motion in the waves caused by the parametric resonance, the fluctuation in GM is designed to be diminished on the waves by U-shaping the hull fore and aft like a fat large ship hull, or the fluctuation in dynamic stability is done to be diminished by increasing the GM on the calm sea. However, the ship with a U-shaped hull fore and aft is large in rolling angle due to the smallness in righting arm at the large heeling angle. Generally regardless of oceanic condition and ship speed, it is impossible to establish the GM absolutely without the primary and secondary synchronizing points. To avoid the unstable roll motion with a low ship speed, it is desirable to do it by the ship speed to be as high as possible. 11 refs., 13 figs., 1 tab.

  16. Eor in Western Europe : Status and Outlook La récupération assistée du pétrole en Europe : situation et perspectives

    Combe J.

    2006-11-01

    Full Text Available More than sixty EOR projects implemented on the onshore oil fields of Western European countries have been taken into consideration. They cover most of the EOR processes, except the CO2 miscible drive, and several of them have been technically and economically successful. The full list of these projects is given, together with a brief description of six of the most significant among them. The conclusions which can be drawn from the publications on this Western Europe EOR experience are that steam injection remains the most efficient process for very viscous oils. The area of its applicability is the same as that found in other countries of the world, plus a successful extension to heterogeneous fissured reservoirs. Polymer injection in moderately viscous oils is confirmed to be very efficient, provided that improvements in stability of the viscous solution can be obtained. These two processes are the most promising ones on a relatively short term in Western Europe onshore. Considering horizontal drilling as an improved oil recovery technique, some experiences have been gained recently in this method. Since 1980, thirteen horizontal wells have been drilled in Western European oil fields, without taking into account the North Sea area. The first results are quite encouraging, mainly thanks to remarkable improvements in drilling performances. An investigation of the oil potential for EOR shows that 40 to 170 Mm3 of additional oil could be recovered from the currently producing onshore fields in Europe by polymer flooding and up to 75 Mm3 by steam drive, given a favorable oil price assumption. Injection of various gases, under miscible or immiscible conditions, has a theoretical potential that could reach the same magnitude as thermal and polymer processes. However the availability of gas required at cheap conditions makes the development of these reserves improbable. Orientations for research coming from this investigation are in favor of an

  17. Anatomical reconstruction of unstable trochanteric fractures through posterior approach

    Partha Saha

    2015-01-01

    Full Text Available Objective Unstable intertrochanteric fractures continue to be a challenge for orthopedic surgeons due to the functional limitations it results in the postoperative period. Anatomical reconstruction of the posteromedial fragment becomes difficult through conventional lateral approach, leading to excessive fracture collapse and limping. Materials and Methods: prospective, nonrandomized study was done with 40 patients. They were operated in prone position through posterior approach. Cancellous screws or SS-wires were used to fix the greater or lesser trochanteric fragments and dynamic hip screw (DHS or dynamic condylar screw (DCS for the main two fragments. Bone grafts were used to pack cavities at the posterior trochanteric regions. Results: Fracture healing occurred earlier compared to conventional lateral approach without excessive fracture collapse in majority of cases (average time to achieve union was 13.8 weeks; range: 10–18 weeks. Good functional recovery was noted with 75% 'Good' or 'Excellent' Harris Hip Scores at 24 weeks. Conclusion: Anatomical reconstruction of unstable trochanteric fractures becomes easier through posterior approach with earlier and better functional recovery.

  18. A chaotic system with a single unstable node

    Sprott, J.C. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Jafari, Sajad, E-mail: sajadjafari@aut.ac.ir [Biomedical Engineering Department, Amirkabir University of Technology, Tehran 15875-4413 (Iran, Islamic Republic of); Pham, Viet-Thanh [School of Electronics and Telecommunications, Hanoi University of Science and Technology, 01 Dai Co Viet, Hanoi (Viet Nam); Hosseini, Zahra Sadat [Biomedical Engineering Department, Amirkabir University of Technology, Tehran 15875-4413 (Iran, Islamic Republic of)

    2015-09-25

    This paper describes an unusual example of a three-dimensional dissipative chaotic flow with quadratic nonlinearities in which the only equilibrium is an unstable node. The region of parameter space with bounded solutions is relatively small as is the basin of attraction, which accounts for the difficulty of its discovery. Furthermore, for some values of the parameters, the system has an attracting torus, which is uncommon in three-dimensional systems, and this torus can coexist with a strange attractor or with a limit cycle. The limit cycle and strange attractor exhibit symmetry breaking and attractor merging. All the attractors appear to be hidden in that they cannot be found by starting with initial conditions in the vicinity of the equilibrium, and thus they represent a new type of hidden attractor with important and potentially problematic engineering consequences. - Highlights: • An unusual example of a three-dimensional dissipative chaotic flow is introduced. • In this system the only equilibrium is an unstable node. • For some values of the parameters, the system has an attracting torus. • This torus can coexist with a strange attractor or with a limit cycle. • These properties are uncommon in three-dimensional systems.

  19. Search for Unstable Heavy and Excited Leptons at LEP2

    Abbiendi, G.; Akesson, P.F.; Alexander, G.; Allison, John; Anderson, K.J.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Bailey, I.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Batley, J.R.; Baumann, S.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Bloodworth, I.J.; Bock, P.; Bohme, J.; Boeriu, O.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Chrisman, D.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couchman, J.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Dallison, S.; Davis, R.; de Roeck, A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Fanfani, A.; Fanti, M.; Faust, A.A.; Feld, L.; Ferrari, P.; Fiedler, F.; Fierro, M.; Fleck, I.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Gorn, W.; Grandi, C.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hajdu, C.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Harin-Dirac, M.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hobson, P.R.; Hocker, James Andrew; Hoffman, Kara Dion; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jimack, M.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klier, A.; Kobayashi, T.; Kobel, M.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kupper, M.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lauber, J.; Lawson, I.; Layter, J.G.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; Lillich, J.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, J.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Marchant, T.E.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Mendez-Lorenzo, P.; Merritt, F.S.; Mes, H.; Meyer, I.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poli, B.; Polok, J.; Przybycien, M.; Quadt, A.; Rembser, C.; Rick, H.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rosati, S.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schmitt, S.; Schoning, A.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Sproston, M.; Stahl, A.; Stephens, K.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Tafirout, R.; Talbot, S.D.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; Torrence, E.; Towers, S.; Trefzger, T.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Voss, H.; Wackerle, F.; Waller, D.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, D.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Zacek, V.; Zer-Zion, D.

    2000-01-01

    Searches for unstable neutral and charged heavy leptons, N and L+-, and for excited states of neutral and charged leptons, nu*, e*, mu*, and tau*, have been performed in e+e- collisions using data collected by the OPAL detector at LEP. The data analysed correspond to an integrated luminosity of about 58pb-1 at a centre-of-mass energy of 183GeV, and about 10pb-1 each at 161GeV and 172GeV. No evidence for new particles was found. Lower limits on the masses of unstable heavy and excited leptons are derived. From the analysis of charged-current, neutral-current, and photonic decays of singly produced excited leptons, upper limits are determined for the ratio of the coupling to the compositeness scale, f/Lambda, for masses up to the kinematic limit. For excited leptons, the limits are established independently of the relative values of the coupling constants f and f'.

  20. Boundary Between Stable and Unstable Regimes of Accretion

    Blinova A. A.

    2014-01-01

    Full Text Available We investigated the boundary between stable and unstable regimes of accretion and its dependence on different parameters. Simulations were performed using a “cubed sphere" code with high grid resolution (244 grid points in the azimuthal direction, which is twice as high as that used in our earlier studies. We chose a very low viscosity value, with alpha-parameter α=0.02. We observed from the simulations that the boundary strongly depends on the ratio between magnetospheric radius rm (where the magnetic stress in the magnetosphere matches the matter stress in the disk and corotation radius rcor (where the Keplerian velocity in the disk is equal to the angular velocity of the star. For a small misalignment angle of the dipole field, Θ = 5°, accretion is unstable if rcor/rm> 1.35, and is stable otherwise. In cases of a larger misalignment angle of the dipole, Θ = 20°, instability occurs at slightly larger values, rcor/rm> 1.41

  1. Gravitationally self-bound quantum states in unstable potentials

    Jääskeläinen, Markku

    2018-04-01

    Quantum mechanics at present cannot be unified with the theory of gravity at the deepest level, and to guide research towards the solution of this fundamental problem, we need to look for ways to observe or refute predictions originating from attempts to combine quantum theory with gravity. The influence of the gravitational field created by the material density given by the wave function itself gives rise to nontrivial phenomena. In this study I consider the wave function for the center-of-mass coordinate of a spherical mass distribution under the influence of the self-interaction of Newtonian gravity. I solve numerically for the ground state in the presence of an unstable potential and find that the energy of the free-space bound state can be lowered despite the nontrapping character of the potential. The center-of-mass ground state becomes increasingly localized for the used unstable potentials, although only in a limited parameter regime. The feebleness of the energy shift makes the observation of these effects demanding and requires further developments in the cooling of material particles. In addition, the influence of gravitational perturbations that are present in typical laboratory settings necessitates the use of extremely quiet and controlled environments such as those provided by recently proposed space-borne experiments.

  2. Malaria infection has spatial, temporal, and spatiotemporal heterogeneity in unstable malaria transmission areas in northwest Ethiopia.

    Kassahun Alemu

    Full Text Available BACKGROUND: Malaria elimination requires successful nationwide control efforts. Detecting the spatiotemporal distribution and mapping high-risk areas are useful to effectively target pockets of malaria endemic regions for interventions. OBJECTIVE: The aim of the study was to identify patterns of malaria distribution by space and time in unstable malaria transmission areas in northwest Ethiopia. METHODS: Data were retrieved from the monthly reports stored in the district malaria offices for the period between 2003 and 2012. Eighteen districts in the highland and fringe malaria areas were included and geo-coded for the purpose of this study. The spatial data were created in ArcGIS10 for each district. The Poisson model was used by applying Kulldorff methods using the SaTScan™ software to analyze the purely temporal, spatial and space-time clusters of malaria at a district levels. RESULTS: The study revealed that malaria case distribution has spatial, temporal, and spatiotemporal heterogeneity in unstable transmission areas. Most likely spatial malaria clusters were detected at Dera, Fogera, Farta, Libokemkem and Misrak Este districts (LLR =197764.1, p<0.001. Significant spatiotemporal malaria clusters were detected at Dera, Fogera, Farta, Libokemkem and Misrak Este districts (LLR=197764.1, p<0.001 between 2003/1/1 and 2012/12/31. A temporal scan statistics identified two high risk periods from 2009/1/1 to 2010/12/31 (LLR=72490.5, p<0.001 and from 2003/1/1 to 2005/12/31 (LLR=26988.7, p<0.001. CONCLUSION: In unstable malaria transmission areas, detecting and considering the spatiotemporal heterogeneity would be useful to strengthen malaria control efforts and ultimately achieve elimination.

  3. Large Eddy Simulation of Unstably Stratified Turbulent Flow over Urban-Like Building Arrays

    Bobin Wang

    2013-01-01

    Full Text Available Thermal instability induced by solar radiation is the most common condition of urban atmosphere in daytime. Compared to researches under neutral conditions, only a few numerical works studied the unstable urban boundary layer and the effect of buoyancy force is unclear. In this paper, unstably stratified turbulent boundary layer flow over three-dimensional urban-like building arrays with ground heating is simulated. Large eddy simulation is applied to capture main turbulence structures and the effect of buoyancy force on turbulence can be investigated. Lagrangian dynamic subgrid scale model is used for complex flow together with a wall function, taking into account the large pressure gradient near buildings. The numerical model and method are verified with the results measured in wind tunnel experiment. The simulated results satisfy well with the experiment in mean velocity and temperature, as well as turbulent intensities. Mean flow structure inside canopy layer varies with thermal instability, while no large secondary vortex is observed. Turbulent intensities are enhanced, as buoyancy force contributes to the production of turbulent kinetic energy.

  4. Inertial and stick-slip regimes of unstable adhesive tape peeling.

    Dalbe, Marie-Julie; Villey, Richard; Ciccotti, Matteo; Santucci, Stéphane; Cortet, Pierre-Philippe; Vanel, Loïc

    2016-05-18

    We present an experimental characterization of the detachment front unstable dynamics observed during the peeling of pressure sensitive adhesives. We use an experimental set-up specifically designed to control the peeling angle θ and the peeled tape length L, while peeling an adhesive tape from a flat substrate at a constant driving velocity V. High-speed imaging allows us to report the evolution of the period and amplitude of the front oscillations, as well as the relative durations of their fast and slow phases, as a function of the control parameters V, L and θ. Our study shows that, as the driving velocity or the peeling angle increases, the oscillations of the peeling front progressively evolve from genuine "stick-slip" oscillations, made of alternating long stick phases and very brief slip phases, to sinusoidal oscillations of amplitude twice the peeling velocity. We propose a model which, taking into account the peeling angle-dependent kinetic energy cost to accelerate and decelerate the peeled tape, explains the transition from the "stick-slip" to the "inertial" regime of the dynamical instability. Using independent direct measurements of the effective fracture energy of the adhesive-substrate joint, we show that our model quantitatively accounts for the two regimes of the unstable dynamics.

  5. Unstable Pore-Water Flow in Intertidal Wetlands

    Barry, D. A.; Shen, C.; Li, L.

    2014-12-01

    Salt marshes are important intertidal wetlands strongly influenced by interactions between surface water and groundwater. Bordered by coastal water, the marsh system undergoes cycles of inundation and exposure driven by the tide. This leads to dynamic, complex pore-water flow and solute transport in the marsh soil. Pore-water circulations occur over vastly different spatial and temporal scales with strong link to the marsh topography. These circulations control solute transport between the marsh soil and the tidal creek, and ultimately affect the overall nutrient exchange between the marsh and coastal water. The pore-water flows also dictate the soil condition, particularly aeration, which influences the marsh plant growth. Numerous studies have been carried out to examine the pore-water flow process in the marsh soil driven by tides, focusing on stable flow with the assumption of homogeneity in soil and fluid properties. This assumption, however, is questionable given the actual inhomogeneous conditions in the field. For example, the salinity of surface water in the tidal creek varies temporally and spatially due to the influence of rainfall and evapotranspiration as well as the freshwater input from upland areas to the estuary, creating density gradients across the marsh surface and within the marsh soil. Many marshes possess soil stratigraphy with low-permeability mud typically overlying high-permeability sandy deposits. Macropores such as crab burrows are commonly distributed in salt marsh sediments. All these conditions are prone to the development of non-uniform, unstable preferential pore-water flow in the marsh soil, for example, funnelling and fingering. Here we present results from laboratory experiments and numerical simulations to explore such unstable flow. In particular, the analysis aims to address how the unstable flow modifies patterns of local pore-water movement and solute transport, as well as the overall exchange between the marsh soil and

  6. Small Enterprise Strategies in an Unstable Public Environment

    Daryl D. Green

    2016-04-01

    Full Text Available Many small business owners in the United States dream about getting a large contract with the federal government, feeling that their lives would be easier if they did. Ironically, there have been numerous occasions where small businesses have gone out of business after being overwhelmed by a government contract. This case study addresses how small businesses can improve their survival and success rate in the public sector with a strategic approach to their operations. It begins by discussing the preparation that goes into federal contracting by small businesses. Case examples of four American companies involved in contracting with the Department of Energy are evaluated. Data collection is achieved through qualitative analysis. The application of these conclusions could increase the survival rate of small businesses operating in an unstable public environment. The study is significant because this research widens contemporary assumptions about strategic thinking for small businesses engaged in government contracting.

  7. Some cases of terrain unstability from the Dolenjska karst area

    Magda Čarman

    2010-12-01

    Full Text Available The paper presents some cases of terrain unstability from the Dolenjska karst area formed in the last yearsaround Žužemberk and Dolenjske Toplice. The Dolenjska karst has its own characteristic way of development. Themain features are thick soil top, mainly composed of clay, and high and strongly fluctuating water table. Presentedare a landslide, two rockfalls and a sinkhole collapse. A landslide nearby Žužemberk was initiated in soil top. Bothrockfalls appeared in tectonically highly disturbed carbonate rocks along the Žužemberk fault. The sinkhole collapsein the area around Dolenjske Toplice developed in tectonically damaged rocks inside the Dolenjska - Notranjskahorst and during a period of heavy rain.

  8. Membrane extraction with thermodynamically unstable diphosphonic acid derivatives

    Horwitz, E.P.; Gatrone, R.C.; Nash, K.L.

    1997-10-14

    Thermodynamically-unstable complexing agents which are diphosphonic acids and diphosphonic acid derivatives (or sulphur containing analogs), like carboxyhydroxymethanediphosphonic acid and vinylidene-1,1-diphosphonic acid, are capable of complexing with metal ions, and especially metal ions in the II, III, IV, V and VI oxidation states, to form stable, water-soluble metal ion complexes in moderately alkaline to highly-acidic media. However, the complexing agents can be decomposed, under mild conditions, into non-organic compounds which, for many purposes are environmentally-nondamaging compounds thereby degrading the complex and releasing the metal ion for disposal or recovery. Uses for such complexing agents as well as methods for their manufacture are also described. 1 fig.

  9. Antisocial personality disorder--stable and unstable subtypes.

    Ullrich, Simone; Coid, Jeremy

    2010-04-01

    There have been criticisms that the criteria for antisocial personality disorder (ASPD) are over-dependent on criminal behavior. This study aimed to identify unrelated criteria of social and behavioral problems and instability, and to investigate their associations in a representative household sample of adults in the UK. Approximately one third of adults with ASPD did not fulfill any of the criteria for instability. They were less aggressive and involved in illegal activities but expressed less remorse for their behaviors. Instability in ASPD was mediated primarily through comorbid anxiety disorders and borderline personality disorder. The concept of Secondary Psychopathy, which has not generally been applied to ASPD, demonstrated many similarities to the unstable subtype.

  10. Hamiltonian approach to the derivation of evolution equations for wave trains in weakly unstable media

    N. N. Romanova

    1998-01-01

    Full Text Available The dynamics of weakly nonlinear wave trains in unstable media is studied. This dynamics is investigated in the framework of a broad class of dynamical systems having a Hamiltonian structure. Two different types of instability are considered. The first one is the instability in a weakly supercritical media. The simplest example of instability of this type is the Kelvin-Helmholtz instability. The second one is the instability due to a weak linear coupling of modes of different nature. The simplest example of a geophysical system where the instability of this and only of this type takes place is the three-layer model of a stratified shear flow with a continuous velocity profile. For both types of instability we obtain nonlinear evolution equations describing the dynamics of wave trains having an unstable spectral interval of wavenumbers. The transformation to appropriate canonical variables turns out to be different for each case, and equations we obtained are different for the two types of instability we considered. Also obtained are evolution equations governing the dynamics of wave trains in weakly subcritical media and in media where modes are coupled in a stable way. Presented results do not depend on a specific physical nature of a medium and refer to a broad class of dynamical systems having the Hamiltonian structure of a special form.

  11. On the Kalman Filter error covariance collapse into the unstable subspace

    A. Trevisan

    2011-03-01

    Full Text Available When the Extended Kalman Filter is applied to a chaotic system, the rank of the error covariance matrices, after a sufficiently large number of iterations, reduces to N+ + N0 where N+ and N0 are the number of positive and null Lyapunov exponents. This is due to the collapse into the unstable and neutral tangent subspace of the solution of the full Extended Kalman Filter. Therefore the solution is the same as the solution obtained by confining the assimilation to the space spanned by the Lyapunov vectors with non-negative Lyapunov exponents. Theoretical arguments and numerical verification are provided to show that the asymptotic state and covariance estimates of the full EKF and of its reduced form, with assimilation in the unstable and neutral subspace (EKF-AUS are the same. The consequences of these findings on applications of Kalman type Filters to chaotic models are discussed.

  12. Augmentation of proximal femoral nail in unstable trochanteric fractures

    Gadegone Wasudeo M.

    2017-01-01

    Full Text Available Introduction: Biomechanically proximal femoral nail (PFN is a better choice of implant, still it is associated with screw breakage, cut out of screw through femoral head, Z effect, reverse Z effect, and lateral migration of screws. The purpose of this study is to evaluate the results of augmented PFN in terms of prevention of postoperative complications and failure rates in unstable trochanteric fractures. Material and methods: We carried out a prospective study of 82 cases with unstable trochanteric femoral fractures from April 2010 to December 2015. Forty-two females and 40 males in the age group between 58 and 81 years were included in this study. There were 45 cases of AO 31 A2 (2.2, 2.3 and 37 cases of AO 31 A3 (3.1, 3.2, 3.3. Fractures were fixed by PFN with augmentation by an additional screw from trochanter to inferior quadrant of femoral head or cerclage wire to strengthen the lateral trochanteric wall. Results: The bone healing is observed in all the cases in the mean period of 14.2 weeks. Nine patients developed complications, including lateral migration of neck screws (n = 5, Z effect (n = 1, infection (n = 2, and breakage of distal interlocking bolt in one case. Removal of screws was required in five cases. Patients were followed up for a mean of 8.4 months. At the end of follow-up the Salvati and Wilson hip function was 32 (out of 40 in 88% of patients. Conclusion: The stabilization of lateral trochanteric wall with additional screw or cerclage wire increases the stability of construct.

  13. Seismic monitoring of the unstable rock slope at Aaknes, Norway

    Roth, M.; Blikra, L. H.

    2009-04-01

    The unstable rock slope at Aaknes has an estimated volume of about 70 million cubic meters, and parts of the slope are moving at a rate between 2-15 cm/year. Amongst many other direct monitoring systems we have installed a small-scale seismic network (8 three-component geophones over an area of 250 x 150 meters) in order to monitor microseismic events related to the movement of the slope. The network has been operational since November 2005 with only a few short-term outages. Seismic data are transferred in real-time from the site to NORSAR for automatic detection processing. The resulting detection lists and charts and the associated waveform are forwarded immediately to the early warning centre of the Municipality of Stranda. Furthermore, we make them available after a delay of about 10-15 minutes on our public project web page (http://www.norsar.no/pc-47-48-Latest-Data.aspx). Seismic monitoring provides independent and complementary data to the more direct monitoring systems at Aaknes. We observe increased seismic activity in periods of heavy rain fall or snow melt, when laser ranging data and extensometer readings indicate temporary acceleration phases of the slope. The seismic network is too small and the velocity structure is too heterogeneous in order to obtain reliable localizations of the microseismic events. In summer 2009 we plan to install a high-sensitive broadband seismometer (60 s - 100 Hz) in the middle of the unstable slope. This will allow us to better constrain the locations of the microseismic events and to investigate potential low-frequency signals associated with the slope movement.

  14. Angular Stable Miniplate Fixation of Chronic Unstable Scaphoid Nonunion.

    Schormans, Philip M J; Brink, Peter R G; Poeze, Martijn; Hannemann, Pascal F W

    2018-02-01

    Background  Around 5 to 15% of all scaphoid fractures result in nonunion. Treatment of long-lasting scaphoid nonunion remains a challenge for the treating surgeon. Healing of scaphoid nonunion is essential for prevention of scaphoid nonunion advanced collapse and the subsequent predictable pattern of radiocarpal osteoarthritis. Purpose  The purpose of this study was to investigate the feasibility of fixation of the scaphoid nonunion with a volar angular stable miniplate and cancellous bone grafting. We hypothesized that this technique could be successful, even in patients with previous surgery for nonunion and in patients with a long duration of nonunion. Patients and Methods  A total of 21 patients enrolled in a single-center prospective cohort study. Healing of nonunion was assessed on multiplanar computed tomography scan of the wrist at a 3-month interval. Functional outcome was assessed by measuring grip strength, range of motion, and by means of the patient-rated wrist and hand evaluation (PRWHE) questionnaire. Results  During follow-up, 19 out of 21 patients (90%) showed radiological healing of the nonunion. The range of motion did not improve significantly. Postoperative PRWHE scores decreased by 34 points. Healing occurred regardless of the length of time of the nonunion (range: 6-183 months) and regardless of previous surgery (38% of patients). Conclusion  Volar angular stable miniplate fixation with autologous cancellous bone grafting is a successful technique for the treatment of chronic unstable scaphoid nonunion, even in patients with long-lasting nonunion and in patients who underwent previous surgery for a scaphoid fracture. Rotational interfragmentary stability might be an important determining factor for the successful treatment of unstable scaphoid nonunion. Level of Evidence  Level IV.

  15. Bohr Hamiltonian with an energy-dependent γ-unstable Coulomb-like potential

    Budaca, R. [Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele (Romania)

    2016-10-15

    An exact analytical solution for the Bohr Hamiltonian with an energy-dependent Coulomb-like γ-unstable potential is presented. Due to the linear energy dependence of the potential's coupling constant, the corresponding spectrum in the asymptotic limit of the slope parameter resembles the spectral structure of the spherical vibrator, however with a different state degeneracy. The parameter free energy spectrum as well as the transition rates for this case are given in closed form and duly compared with those of the harmonic U(5) dynamical symmetry. The model wave functions are found to exhibit properties that can be associated to shape coexistence. A possible experimental realization of the model is found in few medium nuclei with a very low second 0{sup +} state known to exhibit competing prolate, oblate and spherical shapes. (orig.)

  16. Rotation and oscillation of nonlinear dipole vortex in the drift-unstable plasma

    Orito, Kohtaro; Hatori, Tadatsugu.

    1997-10-01

    The behaviors of the nonlinear dipole vortex in the drift unstable plasma are studied by numerical approaches. Model equations used in numerical simulation are derived from two-fluid model and are composed of two equations with respect to the electrostatic potential and the density perturbation. When the initial dipole vortex is inclined at some angle with respect to the direction of the drift velocity, the dipole vortex oscillates or rotates in the first stage. These phenomenon also happen in the stable system. In the second stage, one part of the dipole vortex grows and another decays because of the destabilization. The shrunk vortex rotates around the enlarged vortex. Consequently, a monopole vortex appears out of the dipole vortex. (author)

  17. Diagnosis of Unstable Angina Pectoris Has Declined Markedly with the Advent of More Sensitive Troponin Assays

    D'Souza, Maria; Sarkisian, Laura; Saaby, Lotte

    2015-01-01

    ]) was established in cases of a rise and/or fall of cardiac troponin I together with cardiac ischemic features. Patients with unstable chest discomfort and cardiac troponin I values below the decision limit of myocardial infarction were diagnosed as having unstable angina pectoris. The definition of acute coronary...... syndrome included unstable angina pectoris, NSTEMI, and STEMI. Mortality data were obtained from the Danish Civil Personal Registration System. RESULTS: Of 3762 consecutive patients, 516 had acute coronary syndrome. Unstable angina pectoris was present in 7%, NSTEMI in 67%, and STEMI in 26%. The NSTEMI...... patients were older, more frequently women, and had more comorbidities than patients with unstable angina pectoris and STEMI. At median follow-up of 3.2 years 195 patients had died: 14% of unstable angina pectoris, 45% of NSTEMI, and 25% of STEMI patients. Age-adjusted log-rank statistics revealed...

  18. Effects of an unstable shoe construction on balance in women aged over 50 years

    Ramstrand, Nerrolyn; Thuesen, Anna Helena; Nielsen, Dennis Brandborg

    2010-01-01

    BACKGROUND: Shoes with an unstable sole construction are commonly used as a therapeutic tool by physiotherapists and are widely available from shoe and sporting goods retailers. The aim of this study was to investigate the effects of using an unstable shoe (Masai Barefoot Technology) on standing ....... INTERPRETATION: Results from the present study suggest that, for this group of individuals, use of unstable footwear may improve certain aspects of balance....

  19. Theory of elementary excitations in unstable Bose-Einstein condensates and the instability of sonic horizons

    Leonhardt, U.; Kiss, T.; Oehberg, P.

    2003-01-01

    Like classical fluids, quantum gases may suffer from hydrodynamic instabilities. Our paper develops a quantum version of the classical stability analysis in fluids, the Bogoliubov theory of elementary excitations in unstable Bose-Einstein condensates. In unstable condensates the excitation modes have complex frequencies. We derive the normalization conditions for unstable modes such that they can serve in a mode decomposition of the noncondensed component. Furthermore, we develop approximative techniques to determine the spectrum and the mode functions. Finally, we apply our theory to sonic horizons - sonic black and white holes. For sonic white holes the spectrum of unstable modes turns out to be intrinsically discrete, whereas black holes may be stable

  20. [Usefullness of intrasacral fixation in an extremely unstable lumbosacral spine].

    Nishiura, Tsukasa; Nishiguchi, Mitsuhisa; Kusaka, Noboru; Takayama, Kazuhiro; Maeda, Yasuhiko; Ogihara, Kotaro; Nakagawa, Minoru

    2007-04-01

    Intrasacral fixation technique devised by Jackson is said to provide rigid lumbosacral fixation. We treated 3 cases of lumbosacral lesions using this technique in which lumbosacral segment had become extremely unstable during surgical intervention adding to the effect of original lesions. In all cases, surgeries were performed in 2 stages, intrasacral fixation and anterior stabilization. Case 1: A 52-year-old male was diagnosed fungal discitis and spondylitis at L4 and L5. X-ray showed destruction of the vertebral bodies. L2, L3 and sacrum were fixed posteriorly using the intrasacral fixation technique. One week after the first operation, L4 and L5 vertebral bodies were replaced by long fibula grafts through the extraperitoneal approach. Case 2: A 25-year-old female with cauda equina syndrome and abnormal body form diagnosed as having spondyloptosis in which the entire vertebral body of L5 had descended below the endplate of S1. MR imaging revealed marked canal stenosis at the S1 level. In the first surgery, L5 vertebral body was resected through the transperitoneal approach. After 1 week of bed rest, posterior segments of L5 were resected, L4 was affixed to the sacrum and anterior stabilization was achieved with 2 mesh cages and lumbosacral spine was fixed using the intrasacral fixation technique. Case 3: A 64-year-old female was diagnosed as having pyogenic discitis and osteomyelitis at the L5-S1 level. In spite of successful medical treatment for infection, low back pain continued. Radiologically, L5 vertebral body was shown to have collapsed and slipped anteriorly over the sacrum. L3, L4 and sacrum were fixed by intrasacral fixation. One week after the first operation, the L5/S1 disc and the suppurtive vertebral bodies were resected through the extraperitoneal approach and anterior stabilization was performed with iliac bone grafts. At follow-up for a minimum of 6 months, initial fixation was maintained in all 3 cases and bony fusion was obtained. The

  1. [Bone surgery for unstable hips in patients with cerebral palsy].

    Poul, J; Pesl, M; Pokorná, M

    2004-01-01

    The aim of this retrospective study was to compare the efficacy of femoral osteotomy alone with that of osteotomy combined with an acetabular procedure in patients with unstable hips due to spastic cerebral palsy. Sixty-one hip joints in 50 patients who had shown distinct subluxation or dislocation of the joint were operated on. Eleven patients underwent bilateral surgery. Before bone surgery, soft-tissue release involving both the flexors and adductors was performed on 19 hips. Femoral osteotomy alone was performed on 29 hip joints and combined femoral and pelvic osteotomy was carried out on 32 joints.Twelve resections of the proximal femur in seven patients were evaluated as a separate group. All treated hip joints were assessed by clinical and radiographic examination at a follow-up of more than 5 years. The skiagraphs taken in a strictly neutral position of the lower limbs before surgery and at the final examination were evaluated on the basis of Reimers's migration index and Wiberg's centre-edge angle. The locomotor abilities of each child were categorized according to the Vojta scoring system for locomotor development. The range of motion in the treated hip joint was assessed using the standard S. F. T. R. method. The results obtained were statistically analyzed by the Kruskal- Wallis, one-way ANOVA test. A comparison of the results of femoral osteotomy alone with those of combined femoral and pelvic osteotomy showed that the post-operative values of the migration index and centre-edge angle, as compared with the pre-operative ones, were statistically higher (pVojta rating system. There was no change in the range of motion in the treated hip joints after the operation. In 28, out of the 32 joints treated by combined femoral and pelvic osteotomy, Salter osteotomy was performed and it showed a high efficacy in providing hip joint stability. The main emphasis during surgery was placed on the maximum acetabular rotation laterally. Femoral osteotomy alone was less

  2. Modeling the Radio Foreground for Detection of CMB Spectral Distortions from the Cosmic Dawn and the Epoch of Reionization

    Sathyanarayana Rao, Mayuri; Subrahmanyan, Ravi; Shankar, N Udaya [Raman Research Institute, C V Raman Avenue, Sadashivanagar, Bangalore 560080 (India); Chluba, Jens, E-mail: mayuris@rri.res.in [Jodrell Bank Centre for Astrophysics, University of Manchester, Oxford Road, M13 9PL (United Kingdom)

    2017-05-01

    Cosmic baryon evolution during the Cosmic Dawn and Reionization results in redshifted 21-cm spectral distortions in the cosmic microwave background (CMB). These encode information about the nature and timing of first sources over redshifts 30–6 and appear at meter wavelengths as a tiny CMB distortion along with the Galactic and extragalactic radio sky, which is orders of magnitude brighter. Therefore, detection requires precise methods to model foregrounds. We present a method of foreground fitting using maximally smooth (MS) functions. We demonstrate the usefulness of MS functions over traditionally used polynomials to separate foregrounds from the Epoch of Reionization (EoR) signal. We also examine the level of spectral complexity in plausible foregrounds using GMOSS, a physically motivated model of the radio sky, and find that they are indeed smooth and can be modeled by MS functions to levels sufficient to discern the vanilla model of the EoR signal. We show that MS functions are loss resistant and robustly preserve EoR signal strength and turning points in the residuals. Finally, we demonstrate that in using a well-calibrated spectral radiometer and modeling foregrounds with MS functions, the global EoR signal can be detected with a Bayesian approach with 90% confidence in 10 minutes’ integration.

  3. Non-Abelian magnetized blackholes and unstable attractors

    Mosaffa, A.E. [Institute for Studies in Theoretical Physics and Mathematics (IPM), PO Box 19395-5531, Tehran (Iran, Islamic Republic of)], E-mail: mosaffa@theory.ipm.ac.ir; Randjbar-Daemi, S. [The Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11 34014, Trieste (Italy)], E-mail: seif@ictp.trieste.it; Sheikh-Jabbari, M.M. [Institute for Studies in Theoretical Physics and Mathematics (IPM), PO Box 19395-5531, Tehran (Iran, Islamic Republic of)], E-mail: jabbari@theory.ipm.ac.ir

    2008-01-21

    Fluctuations of non-Abelian gauge fields in a background magnetic charge contain 'tachyonic' modes which as we will show cause an instability of the background. We extend this result to the cases where the background charge (flux) is coupled to four-dimensional Einstein gravity and show that the corresponding spherically symmetric geometries, which in the absence of a cosmological constant are of the form of (colored) Reissner-Nordstroem blackholes or the AdS{sub 2}xS{sup 2}, are also unstable unless the flux assumes its smallest allowed value, in which case the configuration is stable. We discuss the relevance of these instabilities to several places in string theory including various string compactifications and the attractor mechanism. Our results for the latter imply that the attractor mechanism shown to work for the extremal Abelian charged blackholes, cannot be applied in a straightforward way to the extremal non-Abelian colored blackholes, with the exception of the minimally charged stable ones.

  4. Stable and Unstable Rotational Dynamics of a Smartphone

    Loth, Matthew; Gibbons, Chad; Belaiter, Sami; Clarage, James B.

    2017-10-01

    One of the canonical, and memorable, classroom demonstrations from an upper-division mechanics course is to toss a rigid body with three distinct principal moments of inertia into the air, giving it a spin along one of its three principal axes. A student's mechanics textbook itself works great for the body, secured rigidly shut with a rubber band. The book will spin stably about its longest and shortest dimensions, just like a top or gyroscope. What is surprising is that any attempt to spin the book about its intermediate axis (the axis parallel to the book's lines of text) will result in a wildly unstable and chaotic tumbling, which most students find curious enough to warrant staying awake for a subsequent derivation of Euler's equations. However, now that most students read their text "books" off of a tablet or phone, this demonstration may seem outdated. Or is it? Like a textbook, a phone or tablet also has three distinct principal moments. Better still, not only do these solid state devices require no rubber band, but these bodies can collect detailed data on their dynamical state, turning a demonstration into an actual experiment. This article reports the results of this modern version of the classical "book toss" demonstration, fittingly carried out by a team composed of both an old physics professor and a youthful group of three undergraduate students studying physics and engineering.

  5. Unstable patients with retroperitoneal vascular trauma: an endovascular approach.

    Boufi, Mourad; Bordon, Sébastien; Dona, Bianca; Hartung, Olivier; Sarran, Anthony; Nadeau, Sébastien; Maurin, Charlotte; Alimi, Yves S

    2011-04-01

    In hemodynamically unstable patients, the management of retroperitoneal vascular trauma is both difficult and challenging. Endovascular techniques have become an alternative to surgery in several trauma centers. Between 2004 and 2006, 16 patients (nine men, mean age: 46 years, range: 19-79 years) with retroperitoneal vascular trauma and hemodynamic instability were treated using an endovascular approach. The mean injury severity score was 30.7 ± 13.1. Mean systolic blood pressure and the shock index were 74 mm Hg and 1.9, respectively. Vasopressor drugs were required in 68.7% of cases (n = 11). Injuries were attributable to road traffic accidents (n = 15) and falls (n = 1). The hemorrhage sites included the internal iliac artery or its branches (n = 12) with bilateral injury in one case, renal artery (n = 2), abdominal aorta (n = 1), and lumbar artery (n = 1). In all, 14 coil embolizations and three stent-grafts were implanted. The technical success rate was 75%, as early re-embolization was necessary in one case and three patients died during the perioperative period. Six patients died during the period of hospitalization (37.5%). No surgical conversion or major morbidity was reported. In comparison with particulates, coil ± stent-graft may provide similar efficacy with regard to survival, and thus may be a valuable solution when particulate embolization is not available or feasible. Copyright © 2011 Annals of Vascular Surgery Inc. Published by Elsevier Inc. All rights reserved.

  6. Unstable mutations: cause of some neurological hereditary diseases

    Cuenca Berger, P.; Morales Montero, F.

    1999-01-01

    Unstable mutations or amplification of triplets constitute a kind of genetic alteration discovered during the last decade. They had been found inside or near genes important for the normal neurological function of the human being. In some cases, the presence of the amplification causes the inactivation of the gene or the synthesis of a new product which functions different from the original protein. Some common characteristics of diseases caused by the amplification of triplets are that it affects the nervous system and are degenerative in nature. The expression of the manifestations varies according to age. Most of them show genetic anticipation in which the severity of the manifestations increases with each generation and appear at an earlier age. In most cases, the severity of the symptoms is correlated positively to the size of the amplification. The diagnosis of an affected individual in a family may indicate the presence of an altered gene in other relatives. These relatives may not present evident signs of the illness either because it is of late onset or because they carry premutations. The molecular diagnosis of these mutations is important to estimate the risk of developing the disease and/or of transmitting the illness to the descendants and to eliminate the fears of healthy relatives who have inherited normal copies of the gene. (Author) [es

  7. Progressively unstable c2 spondylolysis requiring spinal fusion: case report.

    Nishimura, Yusuke; Ellis, Michael John; Anderson, Jennifer; Hara, Masahito; Natsume, Atsushi; Ginsberg, Howard Joeseph

    2014-01-01

    Cervical spondylolysis is a rare condition defined as a corticated cleft at the pars interarticularis in the cervical spine. This is the case of C2 spondylolysis demonstrating progressive significant instability, which was successfully treated by anterior cervical discectomy and fusion (ACDF) with cervical anterior plate. We describe a 20-year-old female with C2 spondylolysis presenting with progressive worsening of neck pain associated with progressive instability at the C2/3 segment. The progression of instability was well-documented on flexion-extension cervical spine x-rays. She was successfully treated by C2/3 ACDF with anterior cervical plate. Her preoperative significant neck pain resolved immediately after the surgical intervention. She was completely free from neurological symptoms at 1-year postoperative follow-up. We also review the literature and discuss 24 reported cases with C2 spondylolysis. When planning treatment, we should make sure to differentiate this pathology from acute traumatic fracture, which is a hangman's fracture. Assessment of C2/3 instability associated with neurological deficits is extremely important to consider management properly. C2/3 ACDF with cervical plate is biomechanically viable, less invasive, and provides adequate surgical stabilization for unstable C2 spondylolysis.

  8. Breit-Wigner approximation for propagators of mixed unstable states

    Fuchs, Elina

    2016-10-01

    For systems of unstable particles that mix with each other, an approximation of the fully momentum- dependent propagator matrix is presented in terms of a sum of simple Breit-Wigner propagators that are multiplied with finite on-shell wave function normalisation factors. The latter are evaluated at the complex poles of the propagators. The pole structure of general propagator matrices is carefully analysed, and it is demonstrated that in the proposed approximation imaginary parts arising from absorptive parts of loop integrals are properly taken into account. Applying the formalism to the neutral MSSM Higgs sector with complex parameters, very good numerical agreement is found between cross sections based on the full propagators and the corresponding cross sections based on the described approximation. The proposed approach does not only technically simplify the treatment of propagators with non-vanishing off-diagonal contributions, it is shown that it can also facilitate an improved theoretical prediction of the considered observables via a more precise implementation of the total widths of the involved particles. It is also well-suited for the incorporation of interference effects arising from overlapping resonances.

  9. Unstable Angina Treatment in Various Periods of Geomagnetic Activity

    Parshina, S. S.; Tokayeva, L. K.; Afanasiyeva, T. N.; Samsonov, S. N.; Petrova, V. D.; Dolgova, E. M.; Manykina, V. I.; Vodolagina, E. S.

    In 145 patients with unstable angina (UA) there was analized an efficiency of a drug therapy at different types of heliogeophysical activity (HA) during the 23th solar cycle. 83 patients were examined at the period of a lower HA (Kp-index 16,19±0,18), and 62 patients - at the period of a higher HA (Kp-index 17,25±0,21, p<0,05). Baseline severity of patients' condition with UA at the moment of hospitalization at the studied periods did not differ, but the effectiveness of the therapy depended on the period of HA. At the period of a higher HA antianginal effect was stronger than at the lower period of HA (2,27±0,16 points and 1,75±0,12 points, p<0,05), and the need in nitroglycerin on the background of a drug therapy disappeared for 5-7 days quicker than at the period of a lower HA. Maximal hypotensive effect at a higher HA was achieved quicker - on the 3rd day of the treatment, and at a lower HA - only up to hospital discharge (p<0,05). Blood viscosity did not normalize in both of the studied periods, but in small vessels there was noted a decrease of a BV (p<0,05). So, at a higher HA the effectiveness of a drug therapy in patients with UA is higher than at the period of a lower HA.

  10. Vertical ground reaction force analysis during gait with unstable shoes

    Giulia Pereira

    Full Text Available AbstractIntroduction Footwear is no longer just an accessory but also a protection for the musculoskeletal system, and its most important characteristic is comfort.Objectives This study aims to identify and to analyze the vertical ground reaction force in barefoot women and women with unstable shoes.Methodology Five women aged 25 ± 4 years old and mass of 50 ± 7 kg participated in this study. An AMTI force plate was used for data acquisition. The 10 trials for each situation were considered valid where the subject approached the platform with the right foot and at the speed of 4 km/h ± 5%. The instable shoe of this study is used in the practice of physical activity.Results The results showed that the first peak force was higher for the footwear situation, about 5% and significant differences between the barefoot and footwear situation. This significant difference was in the first and second peaks force and in the time of the second peak.Conclusion The values showed that the footwear absorbs approximately 45% of the impact during gait.

  11. Decomposition of thermally unstable substances in film evaporators

    Matz, G

    1982-10-01

    It is widely known that film evaporators are considered to permit really gentle evaporation of heat-sensitive substances. Nevertheless, decomposition of such substance still occurs to an extent depending upon the design and operation of the evaporator. In the following a distinction is made between evaporators with films not generated mechanically, namely the long tube evaporator (lTE) or climbing film evaporator, the falling film evaporator (FFE) and the multiple phase helical tube (MPT) or helical coil evaporators (TFE). Figs 1 and 2 illustrate the mode of operation. A theory of the decomposition of thermally unstable substances in these evaporators is briefly outlined and compared with measurements. Such a theory cannot be developed without any experimental checks; on the other hand, meausrements urgently need a theoretical basis if only to establish what actually has to be measured. All experiments are made with a system of readily adjustable decomposability, namely with aqueous solutions of saccharose; the thermal inversion of this compound can be controlled by addition of various amounts or concentrations of hydrochloric acid. In the absence of any catalysis by hydrochloric acid, the decomposition rates within in the temperature interval studied (60-130/sup 0/C) are so low that the experiments would take much too long and determination of the concentration differences (generally by polarimetric methods) would be very complicated. Such slight effects would also be very unfavourable for comparison with theory. (orig.)

  12. Unstable femoral neck fractures in children - A new treatment option

    Pruthi K

    2006-01-01

    Full Text Available Background : Femoral neck fractures in children are an uncommon but difficult situation. The aim of our study was to evaluate clinical results of closed reduction internal fixation and primary valgus osteotomy fixed with a tension band wire loop in high angled pediatric femoral neck fractures. Methods : In a prospective nonrandomized study conducted at 2 centres, sixteen children and adolescents with a Pauwel type 2/3 fracture neck femur were taken as participants. The femoral neck fractures were stabilized using closed reduction and internal fixation (6.5 mm noncannulated screw and a primary valgus osteotomy fixed with a tension band wire loop preferably within 24-36 hours of injury. Patients were evaluated to determine complications, clinical and radiological outcome. Results : At a mean post operative follow up of 5 years, union was achieved in all cases. Three patients had AVN and one developed coxavara. Results were evaluated using IOWA hip scores. Thirteen patients had an excellent result while 3 patients had a good result. Conclusion : Use of this technique holds promise in treating these difficult unstable fractures. Although results from a larger series are still awaited yet the use of this technique can safely be extended to stable fractures also, to minimize the incidence of complications as nonunion and AVN.

  13. Revealing Bell's nonlocality for unstable systems in high energy physics

    Hiesmayr, Beatrix C.; Gabriel, Andreas; Huber, Marcus; Di Domenico, Antonio; Curceanu, Catalina; Larsson, Jan-Aake; Moskal, Pawel

    2012-01-01

    Entanglement and its consequences - in particular the violation of Bell inequalities, which defies our concepts of realism and locality - have been proven to play key roles in Nature by many experiments for various quantum systems. Entanglement can also be found in systems not consisting of ordinary matter and light, i.e. in massive meson-antimeson systems. Bell inequalities have been discussed for these systems, but up to date no direct experimental test to conclusively exclude local realism was found. This mainly stems from the fact that one only has access to a restricted class of observables and that these systems are also decaying. In this Letter we put forward a Bell inequality for unstable systems which can be tested at accelerator facilities with current technology. Herewith, the long awaited proof that such systems at different energy scales can reveal the sophisticated ''dynamical'' nonlocal feature of Nature in a direct experiment gets feasible. Moreover, the role of entanglement and CP violation, an asymmetry between matter and antimatter, is explored, a special feature offered only by these meson-antimeson systems. (orig.)

  14. Width and partial widths of unstable particles in the light of the Nielsen identities

    Grassi, P.A.; Sirlin, A.; Kniehl, B.A.; Hamburg Univ.

    2001-09-01

    Fundamental properties of unstable particles, including mass, width, and partial widths, are examined on the basis of the Nielsen identities (NI) that describe the gauge dependence of Green functions. In particular, we prove that the pole residues and associated definitions of branching ratios and partial widths are gauge independent to all orders. A simpler, previously discussed definition of branching ratios and partial widths is found to be gauge independent through next-to-next-to-leading order. It is then explained how it may be modified in order to extend the gauge independence to all orders. We also show that the physical scattering amplitude is the most general combination of self-energy, vertex, and box contributions that is gauge independent for arbitrary s, discuss the analytical properties of the NI functions, and exhibit explicitly their one-loop expressions in the Z-γ sector of the Standard Model. (orig.)

  15. Width and partial widths of unstable particles in the light of the Nielsen identities

    Grassi, Pietro A.; Kniehl, Bernd A.; Sirlin, Alberto

    2002-01-01

    Fundamental properties of unstable particles, including mass, width, and partial widths, are examined on the basis of the Nielsen identities (NI) that describe the gauge dependence of Green functions. In particular, we prove that the pole residues and associated definitions of branching ratios and partial widths are gauge independent to all orders. A simpler, previously discussed definition of branching ratios and partial widths is found to be gauge independent through next-to-next-to-leading order. It is then explained how it may be modified in order to extend the gauge independence to all orders. We also show that the physical scattering amplitude is the most general combination of self-energy, vertex, and box contributions that is gauge independent for arbitrary s, discuss the analytical properties of the NI functions, and exhibit explicitly their one-loop expressions in the Z-γ sector of the standard model

  16. Microbial EOR technology; Biseibutsu EOR gijutsu no kenkyu

    Taguchi, M.; Yonebayashi, E. [Tech. Research Center, Japan National Oil Corp., Tokyo (Japan)

    1995-11-10

    This paper describes attempts of establishing an oil recovery technology utilizing microorganisms and of aiming at improving the practicability of that technology. Fiscal 1994 has investigated effects of inorganic salts existing in reservoir beds and NaCl concentrations on proliferation of microorganisms and production of metabolites. The investigation was intended to discuss applicability of microorganisms to environments that are brought closer to actual field conditions. Furthermore, a core sweeping test using sandstone was carried out on the fiscal 1992 separated bacteria, the 4118 bacteria, that has high surfactant production capability. In addition, a sand pack was used to perform a flooding experiment under conditions of 50{degree}C and 50 KSC to evaluate functionality of microorganisms when environments in the reservoir bed are simulated with respect to pressures and temperatures. An oil recovering experiment was carried out using a sandstone with a diameter of 1.5 inches, a length of 1.0 foot and permeability of 600 md, and using Bacillus subtilis 4118 bacteria which attained the lowest interfacial tension among the bacteria examined. A recovery rate of 4.4% Sor was derived in the experiment. A recovery rate of 29.0% Sor at maximum was obtained when Bacillus licheniformis 18-2-a bacteria was supplied into a sand pack filled with silica sand. 20 figs., 7 tabs.

  17. Clinical Course of Two Children with Unstable Hemoglobins : The Effect of Hydroxyurea Therapy

    Loovers, Harriet M.; Tamminga, Nienke; Mulder, Andre B.; Tamminga, Rienk Y. J.

    Case reports on the effect of hydroxyurea (HU) therapy for unstable hemoglobins (Hbs) are sparse; only three adult cases have been reported. We report for the first time on the effect of HU therapy in children carrying unstable Hbs. The first case concerns a female child with a familial history of

  18. Incidence and follow-up of Braunwald subgroups in unstable angina pectoris

    van Miltenburg-van Zijl, A. J.; Simoons, M. L.; Veerhoek, R. J.; Bossuyt, P. M.

    1995-01-01

    OBJECTIVES. This study was performed to establish the prognosis of patients with unstable angina within the subgroups of the Braunwald classification. BACKGROUND. Among many classifications of unstable angina, the Braunwald classification is frequently used. However, the incidence and risk for each

  19. Concluding remarks of the International symposium on structure and reactions of unstable nuclei

    Mueller, A.C.

    1991-01-01

    A brief history of unstable beams is given, followed by a short description of the experimental facilities. The structure and reaction of unstable nuclei is discussed, and the neutron-halo nuclei are studied. Some considerations are given related to exotic-beam facilities. (K.A.) 14 refs., 2 figs

  20. Nonlinear particle-wave kinetics in weakly unstable plasmas

    Breizman, B.N.; Berk, H.L.; Pekker, M.S.

    1996-01-01

    With the motivation to address the behavior of the fusion produced alpha particles in a thermonuclear reactor, a theory is developed for predicting the wave saturation levels and particle transport in weakly unstable systems with a discrete number of modes in the presence of energetic particle sources and sinks. Conditions are established for either steady state or bursting nonlinear scenarios when several modes are excited for cases where there is and there is not resonance overlap. Depending on parameters, the particles can undergo benign relaxation, with only a small fraction of the available free energy released to waves and with no global transport, or the particles can experience rapid global transport caused by a substantial conversion of their free energy into wave energy. When the resonance condition of the particle-wave interaction is varied adiabatically, the particles trapped in a wave are found to form phase space holes or clumps that enhance the particle-wave energy exchange. This mechanism, which has been experimentally observed when there is frequency chirping, causes increased saturation levels of instabilities. If resonance sweeping is imposed externally, the particle free energy can even be tapped in stable systems where background dissipation suppresses linear instability. Externally applied resonance sweeping can be important for alpha particle energy channeling, as well as for understanding fishbone and some Alfven wave instability experiments. Near instability threshold, that is when the destabilizing drive just exceeds the background dissipation, a more sophisticated analysis is developed to predict the correct saturation. To leading order, this problem reduces to an integral equation for the wave amplitude with a temporally non local cubic term. This equation has a self-similar solution that blows-up in a finite time

  1. Ventilation is unstable during drowsiness before sleep onset.

    Thomson, Stuart; Morrell, Mary J; Cordingley, Jeremy J; Semple, Stephen J

    2005-11-01

    Ventilation is unstable during drowsiness before sleep onset. We have studied the effects of transitory changes in cerebral state during drowsiness on breath duration and lung volume in eight healthy subjects in the absence of changes in airway resistance and fluctuations of ventilation and CO2 tension, characteristic of the onset of non-rapid eye movement sleep. A volume-cycled ventilator in the assist control mode was used to maintain CO2 tension close to that when awake. Changes in cerebral state were determined by the EEG on a breath-by-breath basis and classified as alpha or theta breaths. Breath duration and the pause in gas flow between the end of expiratory airflow and the next breath were computed for two alpha breaths which preceded a theta breath and for the theta breath itself. The group mean (SD) results for this alpha-to-theta transition was associated with a prolongation in breath duration from 5.2 (SD 1.3) to 13.0 s (SD 2.1) and expiratory pause from 0.7 (SD 0.4) to 7.5 s (SD 2.2). Because the changes in arterial CO2 tension (PaCO2) are unknown during the theta breaths, we made in two subjects a continuous record of PaCO2 in the radial artery. PaCO2 remained constant from the alpha breaths through to the expiratory period of the theta breath by which time the duration of breath was already prolonged, representing an immediate and altered ventilatory response to the prevailing PaCO2. In the eight subjects, the CO2 tension awake was 39.6 Torr (SD 2.3) and on assisted ventilation 38.0 Torr (1.4). We conclude that the ventilatory instability recorded in the present experiments is due to the apneic threshold for CO2 being at or just below that when awake.

  2. UNSTABLE PLANETARY SYSTEMS EMERGING OUT OF GAS DISKS

    Matsumura, Soko; Thommes, Edward W.; Chatterjee, Sourav; Rasio, Frederic A.

    2010-01-01

    The discovery of over 400 extrasolar planets allows us to statistically test our understanding of the formation and dynamics of planetary systems via numerical simulations. Traditional N-body simulations of multiple-planet systems without gas disks have successfully reproduced the eccentricity (e) distribution of the observed systems by assuming that the planetary systems are relatively closely packed when the gas disk dissipates, so that they become dynamically unstable within the stellar lifetime. However, such studies cannot explain the small semimajor axes a of extrasolar planetary systems, if planets are formed, as the standard planet formation theory suggests, beyond the ice line. In this paper, we numerically study the evolution of three-planet systems in dissipating gas disks, and constrain the initial conditions that reproduce the observed a and e distributions simultaneously. We adopt initial conditions that are motivated by the standard planet formation theory, and self-consistently simulate the disk evolution and planet migration, by using a hybrid N-body and one-dimensional gas disk code. We also take into account eccentricity damping, and investigate the effect of saturation of corotation resonances on the evolution of planetary systems. We find that the a distribution is largely determined in a gas disk, while the e distribution is determined after the disk dissipation. We also find that there may be an optimum disk mass which leads to the observed a-e distribution. Our simulations generate a larger fraction of planetary systems trapped in mean-motion resonances (MMRs) than the observations, indicating that the disk's perturbation to the planetary orbits may be important to explain the observed rate of MMRs. We also find a much lower occurrence of planets on retrograde orbits than the current observations of close-in planets suggest.

  3. Unstable gravitino dark matter prospects for indirect and direct detection

    Grefe, Michael

    2011-11-01

    We confront the signals expected from unstable gravitino dark matter with observations of indirect dark matter detection experiments in all possible cosmic-ray channels. For this purpose we calculate in detail the gravitino decay widths in theories with bilinear violation of R parity, particularly focusing on decay channels with three particles in the final state. Based on these calculations we predict the fluxes of gamma rays, charged cosmic rays and neutrinos expected from decays of gravitino dark matter. Although the predicted spectra could in principal explain the anomalies observed in the cosmic ray positron and electron fluxes as measured by PAMELA and Fermi LAT, we find that this possibility is ruled out by strong constraints from gamma-ray and antiproton observations. Therefore, we employ current data of indirect detection experiments to place strong constraints on the gravitino lifetime and the strength of R-parity violation. In addition, we discuss the prospects of forthcoming searches for a gravitino signal in the spectrum of cosmic-ray antideuterons, finding that they are in particular sensitive to rather low gravitino masses. Finally, we discuss in detail the prospects for detecting a neutrino signal from gravitino dark matter decays, finding that the sensitivity of neutrino telescopes like IceCube is competitive to observations in other cosmic ray channels, especially for rather heavy gravitinos. Moreover, we discuss the prospects for a direct detection of gravitino dark matter via R-parity violating inelastic scatterings off nucleons. We find that, although the scattering cross section is considerably enhanced compared to the case of elastic gravitino scattering, the expected signal is many orders of magnitude too small in order to hope for a detection in underground detectors. (orig.)

  4. Unstable gravitino dark matter prospects for indirect and direct detection

    Grefe, Michael

    2011-11-15

    We confront the signals expected from unstable gravitino dark matter with observations of indirect dark matter detection experiments in all possible cosmic-ray channels. For this purpose we calculate in detail the gravitino decay widths in theories with bilinear violation of R parity, particularly focusing on decay channels with three particles in the final state. Based on these calculations we predict the fluxes of gamma rays, charged cosmic rays and neutrinos expected from decays of gravitino dark matter. Although the predicted spectra could in principal explain the anomalies observed in the cosmic ray positron and electron fluxes as measured by PAMELA and Fermi LAT, we find that this possibility is ruled out by strong constraints from gamma-ray and antiproton observations. Therefore, we employ current data of indirect detection experiments to place strong constraints on the gravitino lifetime and the strength of R-parity violation. In addition, we discuss the prospects of forthcoming searches for a gravitino signal in the spectrum of cosmic-ray antideuterons, finding that they are in particular sensitive to rather low gravitino masses. Finally, we discuss in detail the prospects for detecting a neutrino signal from gravitino dark matter decays, finding that the sensitivity of neutrino telescopes like IceCube is competitive to observations in other cosmic ray channels, especially for rather heavy gravitinos. Moreover, we discuss the prospects for a direct detection of gravitino dark matter via R-parity violating inelastic scatterings off nucleons. We find that, although the scattering cross section is considerably enhanced compared to the case of elastic gravitino scattering, the expected signal is many orders of magnitude too small in order to hope for a detection in underground detectors. (orig.)

  5. Salvianolate injection in the treatment of unstable angina pectoris

    Zhang, Dan; Wu, Jiarui; Liu, Shi; Zhang, Xiaomeng; Zhang, Bing

    2016-01-01

    Abstract Background: To systematically evaluate the clinical efficacy and safety of Salvianolate injection in the treatment of unstable angina pectoris (UAP). Methods: Using literature databases, we conducted a thorough and systematic retrieval of randomized controlled trials (RCTs) that using Salvianolate injection for treating UAP. The Cochrane Risk of Bias Assessment Tool was used to evaluate the methodological quality of the RCTs, and then the data were extracted and meta-analyzed by RevMan5.2 software. Results: A total of 22 RCTs with 2050 participants were included. The meta-analysis indicated that the combined use of Salvianolate injection and western medicine (WM) in the treatment of UAP can achieve a superior effect in angina pectoris total effective rate (risk ratio [RR] = 1.22, 95% confidence interval [CI] (1.17, 1.27), Z = 10.15, P < 0.00001], and the total effectiveness rate of electrocardiogram [RR = 1.26, 95% CI (1.19,1.34), Z = 7.77, P < 0.00001]. In addition, Salvianolate injection can improve the nitroglycerin withdrawal rate and the serum level of NO, decrease high-sensitivity C-reactive protein. Adverse drug reactions (ADRs) or adverse drug events (ADEs) were reported in 6 RCTs involving 15 cases; however, there were no serious ADRs/ADEs. Conclusion: Based on the systematic review, the combined use of Salvianolate injection and WM in the treatment of UAP can achieve a better effect; however, there was no definitive conclusion about its safety. More the large-sample and multicenter RCTs are needed to support its clinical usage. PMID:28002341

  6. The azimuthally anisotropic emission of unstable light nuclear in the heavy ion collisions at intermediate energy

    He Zhiyong; Jin Genming; Li Zuyu; Duan Limin; Dai Guangxi; Zhang Baoguo; Wu Heyu; Wen Wanxin; Qi Yujin; Luo Qingzheng

    1996-01-01

    The unstable light nuclei emitted in the interaction of 40 Ar on 197 Au have been detected at energy of 25 MeV/u by using particle-particle correlation measurement at small relative angle. Their in-plane and out-of-plane emission were measured for three bins of experimentally estimated impact parameter. The enhanced in-plane emission for mid-rapidity unstable nuclei is observed. This enhanced in-plane emission becomes stronger with increasing of impact parameter, but changes small with the mass of unstable nuclei. The in-plane enhancement decreases slightly with the energy of excited state of unstable nuclei. For projectile-like unstable nuclei, the in-plane emission dominates as expected

  7. Mixing height over water and its role on the correlation between temperature and humidity fluctuations in the unstable surface layer

    Sempreviva, A.M.; Gryning, Sven-Erik

    2000-01-01

    layer over land, but it is nearly constant over a 24-hour cycle. During summer, the mixed layer is higher than during winter. A second inversion was often observed. A case study of the development of the mixed layer over the sea under near-neutral and unstable atmospheric conditions during six...... consecutive days is presented. A zero-order mixed-layer height model is applied. In addition to momentum and heat fluxes the effect of subsidence was found to be important for the evolution of the mixed layer over the sea. The modelled evolution of z(i) compared successfully with measurements. We have...

  8. Persistence of unstable and stable chromosome aberrations in lymphocytes of cancer patients treated with radiotherapy

    Di Giorgio, M.; Vallerga, M.B.; Taja, M.R. [Autoridad Regulatoria Nuclear, Buenos Aires (Argentina); Sardi, M. [Hospital Italiano - Mevaterapia, Buenos Aires (Argentina)

    2006-07-01

    Background: Radiation-induced DNA damage in human lymphocytes has equal probability of producing both stable or unstable chromosome aberrations (C.A.). Reports of its in vivo persistence show considerable variations. The quantification of unstable C.A. (dicentrics) in peripheral blood lymphocytes (P.B.L.) is the most reliable biological method for estimating whole-body doses of recent overexposures to ionizing radiation. Given that during the division of T cell precursors, proliferative death of cells containing dicentrics reduces the number of such lymphocytes in peripheral blood, dicentric methodology should be modified to account for past exposures. Micronuclei (M.N.) in cytokinesis-blocked human P.B.L. are well established bio markers for assessing radiation damage in vivo. However, persistence of radiation induced M.N. is limited. Unlike dicentrics and M.N., stable C.A. (translocations) identified at present by the FISH technique, seem to be an adequate indicator for the dosimetric evaluation of past exposures, since translocations are not selected against during mitotic division in the haematopoietic stem cells compartment. Nevertheless, for partial -body exposures with high dose there is some evidence that the decline with time of dicentrics causes some reduction in the yield of translocations. Purpose: To assess the persistence along time of dicentrics, M.N. and translocations in lymphocytes of cancer patients after radiotherapy in order to model changes in C.A. frequencies with partial-body exposures. Materials and methods: 22 cancer patients with different tumor sites, treated with radiotherapy, were evaluated through dicentric chromosome, M.N. and FISH techniques with a follow-up time of up to 90 months after the end of radiotherapy. Regression analysis were performed: 1) for dicentric and for M.N. frequencies in relation to time after the end of radiotherapy and total tumor dose; 2) for the percentage of uns table cells in relation to time after the end

  9. Scaling Laws for Unstable Interfaces Driven by Strong Shocks in Cylindrical Geometry

    Zhang, Q.; Graham, M.J.; Graham, M.J.

    1997-01-01

    The Richtmyer-Meshkov (RM) instability is an interfacial interface between two fluids of different densities driven by shock waves and plays an important role in the studies of inertial confinement fusion and of supernovas. So far, most of the studies are for RM unstable interfaces driven by weak or intermediate shocks in planar geometry. For experiments conducted at the Nova laser, the unstable material interface is accelerated by very strong shocks. In this Letter, we present scaling laws for the RM unstable interface driven by strong imploding and exploding shocks. copyright 1997 The American Physical Society

  10. Investigation of unstable periodic space-time states in distributed active system with supercritical current

    Koronovskij, A.A.; Rempen, I.S.; Khramov, A.E.

    2003-01-01

    The set of the unstable periodic space-time states, characterizing the chaotic space-time dynamics of the electron beam with the supercritical current in the Pierce diode is discussed. The Lyapunov indicators of the revealed instable space-time states of the chaotic dynamics of the distributed self-excited system are calculated. It is shown that change in the set of the unstable periodic states in dependence on the Pierce parameter is determined by change in the various orbits stability, which is demonstrated by the values of senior Lyapunov unstable state index [ru

  11. Diagnostic possibilities of radionuclide investigation in patterns with stable and unstable angina pectoris

    Ponomareva, A.G.; Zudbinov, Yu.I.; Sokolov, O.K.; Kudinov, V.I.

    1986-01-01

    Myocardial radiocardiography and scintigraphy with 99m Tc-pyrophosphate was performed in 58 patients with stable angina and 60 patients with unstable angina. In patients with stable angina, positive scintigrams were mostly recorded after anginal attacks. Their central hemodynamic parameters deteriorated progressively as angina increased in severity. Patients with unstable angina typically showed myocardial accumulation of the label that was unrelated to anginal attacks and recordable by direct-projection scintigraphy. The assessment of myocardial radiocardiographic and scintigraphic data allows one to differentiate between stable and unstable angina

  12. When do anterior external or internal fixators provide additional stability in an unstable (Tile C) pelvic fracture? A biomechanical study.

    Mcdonald, E; Theologis, A A; Horst, P; Kandemir, U; Pekmezci, M

    2015-12-01

    This study aimed at evaluating the additional stability that is provided by anterior external and internal fixators in an unstable pelvic fracture model (OTA 61-C). An unstable pelvic fracture (OTA 61-C) was created in 27 synthetic pelves by making a 5-mm gap through the sacral foramina (posterior injury) and an ipsilateral pubic rami fracture (anterior injury). The posterior injury was fixed with either a single iliosacral (IS) screw, a single trans-iliac, trans-sacral (TS) screw, or two iliosacral screws (S1S2). Two anterior fixation techniques were utilized: external fixation (Ex-Fix) and supra-acetabular external fixation and internal fixation (In-Fix); supra-acetabular pedicle screws connected with a single subcutaneous spinal rod. The specimens were tested using a nondestructive single-leg stance model. Peak-to-peak (P2P) displacement and rotation and conditioning displacement (CD) were calculated. The Ex-Fix group failed in 83.3 % of specimens with concomitant single-level posterior fixation (Total: 15/18-7 of 9 IS fixation, 8 of 9 TS fixation), and 0 % (0/9) of specimens with concomitant two-level (S1S2) posterior fixation. All specimens with the In-Fix survived testing except for two specimens treated with In-Fix combined with IS fixation. Trans-sacral fixation had higher pubic rotation and greater sacral and pubic displacement than S1S2 (p < 0.05). Rotation of the pubis and sacrum was not different between In-Fix constructs combined with single-level IS and TS fixation. In this model of an unstable pelvic fracture (OTA 61-C), anterior fixation with an In-Fix was biomechanically superior to an anterior Ex-Fix in the setting of single-level posterior fixation. There was no biomechanical difference between the In-Fix and Ex-Fix when each was combined with two levels of posterior sacral fixation.

  13. Disabilities caused by unstable mutations in Costa Rica

    Patricia Cuenca

    2004-09-01

    Full Text Available La distrofia miotónica tipo1 (DM1 y el síndrome del cromosoma X frágil (FRAXA son dos enfermedades hereditarias relativamente comunes. Ambas constituyen ejemplos de un nuevo tipo de mecanismo mutacional, llamado mutaciones inestables o dinámicas, expansión de tripletas, o amplificación del ADN. La DM1 se considera como la distrofia muscular más frecuente en los adultos y FRAXA es la principal causa de retardo mental hereditario. Este trabajo presenta resultados actualizados de un estudio prospectivo no aleatorio en pacientes clínicamente afectados, que se realiza con el objetivo de confirmar el diagnóstico con técnicas moleculares (Hibridación de Southern y reacción en cadena de la polimerasa, PCR, y llevar a cabo el tamizaje en cascada del resto de la familia para ofrecerles consejo genético adecuado. Se confirmó el diagnóstico clínico inicial en la mayoría de los casos de distrofia miotónica, pero en los casos con retardo mental, más de la mitad de los análisis resultaron negativos para la amplificación en el gen FMR1, específica de FRAXA. La razón principal para esto podría ser el cuadro clínico muy sutil que muestran los niños afectados antes de la pubertad. Los únicos métodos disponibles para prevenir estas discapacidades por el momento son, el tamizaje en cascada, el consejo genético y el aborto selectivo. De los cuales, el último no se puede llevar a cabo según las leyes vigentes en Costa Rica.Myotonic dystrophy and fragile X syndrome are two genetically determined relatively common disabilities. Both are examples of a new type of mutation mechanism called unstable or dynamic mutations, triple repeats expansions or DNA amplification. Fragile X syndrome is recognized as the main cause of hereditary mental retardation and myotonic dystrophy is considered the most common muscular dystrophy of adults. This is a prospective non randomized study of clinically affected people, in order to confirm the diagnosis with

  14. Percutaneous pedicle screw for unstable spine fractures in polytraumatized patients: A report of two cases

    Boon Beng Tan

    2012-01-01

    Full Text Available Unstable spine fractures commonly occur in the setting of a polytraumatized patient. The aim of management is to balance the need for early operative stabilization and prevent additional trauma due to the surgery. Recent published literature has demonstrated the benefits of early stabilization of an unstable spine fracture particularly in patients with higher injury severity score (ISS. We report two cases of polytrauma with unstable spine fractures stabilized with a minimally invasive percutaneous pedicle screw instrumentation system as a form of damage control surgery. The patients had good recovery from the polytrauma injuries. These two cases illustrate the role of minimally invasive stabilization, its limitations and technical pitfalls in the management of unstable spine fractures in the polytrauma setting as a form of damage control surgery.

  15. A priori which-way information in quantum interference with unstable particles

    Krause, D.E.; Fischbach, E.; Rohrbach, Z.J.

    2014-01-01

    If an unstable particle used in a two-path interference experiment decays before reaching a detector, which-way information becomes available that reduces the detected interference fringe visibility V. Here we argue that even when an unstable particle does not decay while in the interferometer, a priori which-way information is still available in the form of path predictability P which depends on the particle's decay rate Γ. We further demonstrate that in a matter-wave Mach–Zehnder interferometer using an excited atom with an appropriately tuned cavity, P is related to V through the duality relation P 2 +V 2 =1. - Highlights: • Even undecayed unstable particles exhibit novel interference effects. • Interference is studied in a Mach–Zehnder interferometer with a cavity. • More which-way information is available when using unstable particles. • A relation between which-way information and interference is satisfied

  16. Unstable pigment mutants of Chlorella vulgaris B. as induced by UV irradiation

    Chankova, S.; Vinarova, K.

    1987-01-01

    The dynamics of arising of unstable 'segregating' pigment mutants of Chlorella vulgaris B. has been investigated in dependence on the dose of UV-rays applied and the macro- and microstructural changes taking place. The mutants are found to occur with a low frequency, irrespective of the dose applied and the presence or absence of photo-reactivation. A constantly recurring process of decomposition into two subclones is observed: light green (unstable) and yellow-green (stable). The existence of two cellular populations - structurally damaged and structurally undamaged - in the light-green unstable subclone has been demonstrated. There exists a qualitative and a quantitative correlation between the structural deformations in the cell and the dose with which the unstable pigment mutants are induced. Disturbances in the cell division are observed,resulting in delayed growth rate and the formation of small colonies

  17. Monitoring cardiac output during hyperbaric oxygen treatment of haemodynamically unstable patients

    Hansen, Marco Bo; Treschow, Frederik; Skielboe, Martin

    2013-01-01

    Patients suffering from necrotizing fasciitis (NF) are often haemodynamically unstable and require extended monitoring of cardiovascular parameters; yet this is limited during hyperbaric oxygen treatment (HBOT). We aimed to evaluate the use and safety of transoesophageal Doppler (TED) monitoring ...

  18. Selection of unstable patterns and control of optical turbulence by Fourier plane filtering

    Mamaev, A.V.; Saffman, M.

    1998-01-01

    We report on selection and stabilization of transverse optical patterns in a feedback mirror experiment. Amplitude filtering in the Fourier plane is used to select otherwise unstable spatial patterns. Optical turbulence observed for nonlinearities far above the pattern formation threshold...

  19. Citrobacter rodentium is an unstable pathogen showing evidence of significant genomic flux.

    Nicola K Petty

    2011-04-01

    Full Text Available Citrobacter rodentium is a natural mouse pathogen that causes attaching and effacing (A/E lesions. It shares a common virulence strategy with the clinically significant human A/E pathogens enteropathogenic E. coli (EPEC and enterohaemorrhagic E. coli (EHEC and is widely used to model this route of pathogenesis. We previously reported the complete genome sequence of C. rodentium ICC168, where we found that the genome displayed many characteristics of a newly evolved pathogen. In this study, through PFGE, sequencing of isolates showing variation, whole genome transcriptome analysis and examination of the mobile genetic elements, we found that, consistent with our previous hypothesis, the genome of C. rodentium is unstable as a result of repeat-mediated, large-scale genome recombination and because of active transposition of mobile genetic elements such as the prophages. We sequenced an additional C. rodentium strain, EX-33, to reveal that the reference strain ICC168 is representative of the species and that most of the inactivating mutations were common to both isolates and likely to have occurred early on in the evolution of this pathogen. We draw parallels with the evolution of other bacterial pathogens and conclude that C. rodentium is a recently evolved pathogen that may have emerged alongside the development of inbred mice as a model for human disease.

  20. Experiments in nonlinear dynamics using control-based continuation: Tracking stable and unstable response curves

    Bureau, Emil; Schilder, Frank; Santos, Ilmar

    2014-01-01

    We show how to implement control-based continuation in a nonlinear experiment using existing and freely available software. We demonstrate that it is possible to track the complete frequency response, including the unstable branches, for a harmonically forced impact oscillator.......We show how to implement control-based continuation in a nonlinear experiment using existing and freely available software. We demonstrate that it is possible to track the complete frequency response, including the unstable branches, for a harmonically forced impact oscillator....

  1. Considerations concering the generalization of the Dirac equations to unstable fermions

    Kniehl, Bernd A.; Sirlin, Alberto

    2014-08-01

    We discuss the generalization of the Dirac equations and spinors in momentum space to free unstable spin-1/2 fermions taking into account the fundamental requirement of Lorentz covariance. We derive the generalized adjoint Dirac equations and spinors, and explain the very simple relation that exists, in our formulation, between the unstable and stable cases. As an application of the generalized spinors, we evaluate the probability density. We also discuss the behavior of the generalized Dirac equations under time reversal.

  2. One-dimensional unstable eigenfunction and manifold computations in delay differential equations

    Green, Kirk; Krauskopf, Bernd; Engelborghs, Koen

    2004-01-01

    In this paper we present a new numerical technique for computing the unstable eigenfunctions of a saddle periodic orbit in a delay differential equation. This is used to obtain the necessary starting data for an established algorithm for computing one-dimensional (1D) unstable manifolds of an associated saddle fixed point of a suitable Poincare map. To illustrate our method, we investigate an intermittent transition to chaos in a delay system describing a semiconductor laser subject to phase-conjugate feedback

  3. Diagnosis of unstable angina pectoris has declined markedly with the advent of more sensitive troponin assays.

    D'Souza, Maria; Sarkisian, Laura; Saaby, Lotte; Poulsen, Tina S; Gerke, Oke; Larsen, Torben B; Diederichsen, Axel C P; Jangaard, Nikolaj; Diederichsen, Søren Z; Hosbond, Susanne; Hove, Jens; Thygesen, Kristian; Mickley, Hans

    2015-08-01

    Since the arrival of the universal definition of myocardial infarction more sensitive troponin assays have been developed. How these occurrences have influenced the proportions and clinical features of the components of acute coronary syndrome have not been studied prospectively in unselected hospital patients. During 2010 we evaluated all patients in whom cardiac troponin I had been measured at a single university hospital. The diagnosis of acute myocardial infarction (ST-elevation myocardial infarction [STEMI] or non-ST-elevation myocardial infarction [NSTEMI]) was established in cases of a rise and/or fall of cardiac troponin I together with cardiac ischemic features. Patients with unstable chest discomfort and cardiac troponin I values below the decision limit of myocardial infarction were diagnosed as having unstable angina pectoris. The definition of acute coronary syndrome included unstable angina pectoris, NSTEMI, and STEMI. Mortality data were obtained from the Danish Civil Personal Registration System. Of 3762 consecutive patients, 516 had acute coronary syndrome. Unstable angina pectoris was present in 7%, NSTEMI in 67%, and STEMI in 26%. The NSTEMI patients were older, more frequently women, and had more comorbidities than patients with unstable angina pectoris and STEMI. At median follow-up of 3.2 years 195 patients had died: 14% of unstable angina pectoris, 45% of NSTEMI, and 25% of STEMI patients. Age-adjusted log-rank statistics revealed differences in mortality: NSTEMI vs unstable angina pectoris (P = .0091) and NSTEMI vs STEMI (P = .0045). The application of the universal definition together with the use of a contemporary troponin assay seems to have reduced the proportion of patients with unstable angina pectoris to the benefit of patients with NSTEMI. Despite this, NSTEMI patients have a sustained higher mortality than patients with STEMI. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Can Unstable Shoe Be Used As a Safety Training Shoe for Rehabilitation Exercises?

    Amin Gandomkar

    2014-04-01

    Full Text Available Objective: Unstable shoes have been recommended to osteoarthritis patients in order to reduce walking injuries. The aim of this study was to test the effect of unstable shoe on biomechanical selected variables related to injury during stanse phase of running. Materials & Methods: Twenty five healthy young male students available men (21±2.27years participated in this study. Subjects were asked to ran on the force plate in barefoot, with unstable and control shoe conditions. Active and passive joint power, peak anterior-posterior forces, active and passive vertical force, loading rate and impulse of posterior and passive vertical forces variables were recorded using synchronizing force plate and video camera and calculated in MATLAB software. A repeated measure of ANOVA used to test the hypothesis in SPSS software (version 20, p<0.05. Results: negative power at Ankle joint decreased significantly by 49%, 35% using unstable shoe compared to contol shoe and barefoot conditions respectively (P=0.02,P<0.05. Furthemore, unstable shoe decreased significantly the active ankle power compared to barefoot condition by 23% (P=0.01. Loading rate and peak of passive vertical force, impulse and peak of posterior force increased significantly in unstable shoe compared to control shoe (P<0.05. Conclusion: Unstable shoe increased some of running related injuries risk factors such as Loading rate and peak of passive vertical force, impulse and peak of posterior force. Furthemore, this shoe could decrease absorption potential shank muscles and ankle active stability compared to control shoe. However, with increase of ankle active power compared to barefoot and lower anterior force, Unstable shoe could improve the ankle joint force generation and propulsion potential.

  5. Dynamical formation of a hairy black hole in a cavity from the decay of unstable solitons

    Sanchis-Gual, Nicolas; Font, José A; Carlos Degollado, Juan; Herdeiro, Carlos; Radu, Eugen

    2017-01-01

    Recent numerical relativity simulations within the Einstein–Maxwell–(charged-)Klein–Gordon (EMcKG) system have shown that the non-linear evolution of a superradiantly unstable Reissner–Nordström black hole (BH) enclosed in a cavity, leads to the formation of a BH with scalar hair. Perturbative evidence for the stability of such hairy BHs has been independently established, confirming they are the true endpoints of superradiant instability. The same EMcKG system admits also charged scalar soliton-type solutions, which can be either stable or unstable. Using numerical relativity techniques, we provide evidence that the time evolution of some of these unstable solitons leads, again, to the formation of a hairy BH. In some other cases, unstable solitons evolve into a (bald) Reissner–Nordström BH. These results establish that the system admits two distinct channels to form hairy BHs at the threshold of superradiance: growing hair from an unstable (bald) BH, or growing a horizon from an unstable (horizonless) soliton. Some parallelism with the case of asymptotically flat boson stars and Kerr BHs with scalar hair is drawn. (paper)

  6. Dynamical formation of a hairy black hole in a cavity from the decay of unstable solitons

    Sanchis-Gual, Nicolas; Degollado, Juan Carlos; Font, José A.; Herdeiro, Carlos; Radu, Eugen

    2017-08-01

    Recent numerical relativity simulations within the Einstein-Maxwell-(charged-)Klein-Gordon (EMcKG) system have shown that the non-linear evolution of a superradiantly unstable Reissner-Nordström black hole (BH) enclosed in a cavity, leads to the formation of a BH with scalar hair. Perturbative evidence for the stability of such hairy BHs has been independently established, confirming they are the true endpoints of superradiant instability. The same EMcKG system admits also charged scalar soliton-type solutions, which can be either stable or unstable. Using numerical relativity techniques, we provide evidence that the time evolution of some of these unstable solitons leads, again, to the formation of a hairy BH. In some other cases, unstable solitons evolve into a (bald) Reissner-Nordström BH. These results establish that the system admits two distinct channels to form hairy BHs at the threshold of superradiance: growing hair from an unstable (bald) BH, or growing a horizon from an unstable (horizonless) soliton. Some parallelism with the case of asymptotically flat boson stars and Kerr BHs with scalar hair is drawn.

  7. Direct numerical simulation of stable and unstable turbulent thermal boundary layers

    Hattori, Hirofumi; Houra, Tomoya; Nagano, Yasutaka

    2007-01-01

    This paper presents direct numerical simulations (DNS) of stable and unstable turbulent thermal boundary layers. Since a buoyancy-affected boundary layer is often encountered in an urban environmental space where stable and unstable stratifications exist, exploring a buoyancy-affected boundary layer is very important to know the transport phenomena of the flow in an urban space. Although actual observation may qualitatively provide the characteristics of these flows, the relevant quantitative turbulent quantities are very difficult to measure. Thus, in order to quantitatively investigate a buoyancy-affected boundary layer in detail, we have here carried out for the first time time- and space-developing DNS of slightly stable and unstable turbulent thermal boundary layers. The DNS results show the quantitative turbulent statistics and structures of stable and unstable thermal boundary layers, in which the characteristic transport phenomena of thermally stratified boundary layers are demonstrated by indicating the budgets of turbulent shear stress and turbulent heat flux. Even though the input of buoyant force is not large, the influence of buoyancy is clearly revealed in both stable and unstable turbulent boundary layers. In particular, it is found that both stable and unstable thermal stratifications caused by the weak buoyant force remarkably alter the structure of near-wall turbulence

  8. Arm (Advanced Reservoir Management Vs. Eor Gestion avancée de réservoir contre récupération assistée des hydrocarbures (RAH

    Chierici G. L.

    2006-11-01

    Full Text Available Advanced Reservoir Management (ARM techniques aimed at a better reservoir coverage by injected fluid(s through the improvement of interwell connectivity and recourse to gravity drainage are shown to have a better chance than EOR techniques in improving oil recovery with satisfactory economic results. Les techniques de gestion avancée de réservoir (ARM, Advanced Reservoir Management visant une meilleure couverture du réservoir par les fluides injectés grâce à l'amélioration des interconnexions entre les puits et au recours au drainage par gravité semblent offrir plus de possibilités que les techniques de RAH, pour améliorer la récupération du pétrole dans de bonnes conditions économiques.

  9. Isolation and Purification of Unstable Iridoid Glucosides from Traditional Chinese Medicine by Preparative High Performance Liquid Chromatography Coupled with Solid-phase Extraction

    LI Cun-man; XIAO Yuan-sheng; XUE Xing-ya; FENG Jia-tao; ZHANG Xiu-li; LIANG Xin-miao

    2011-01-01

    An efficient preparative method was successfully developed for isolation and purification of unstable components from medicinal plant extracts, using a combined method of preparative high performance liquid chro matography(HPLC) and solid-phase extraction(SPE). The aim of this study was to obtain an effective method with high preparative efficiency and importantly to avoid the transformation of unstable compounds. The preparative HPLC system was based on an LC/MS controlled four-channel autopurification system. The SPE method was per formed with a C1s packing material to trap the target compounds and to remove the acidic additive derived from the mobile phase. Using this method, the unstable iridoid glucosides(IGs) as model compounds were successfully iso lated and purified from the extract of Hedyotis diffusa Willd. Six IGs(including one new minor IG) and one nucleo tide compound were simultaneously obtained, each with a purity of >91% as determined by HPLC. The structures of the isolated compounds were identified by UPLC/Q-TOF MS, UV, ID and/or 2D NMR. It was demonstrated that the combination of preparative HPLC with SPE is a versatile tool for preparative purification of unstable compounds from complex natural products.

  10. Isolation and Purification of Unstable Iridoid Glucosides from Traditional Chinese Medicine by Preparative High Performance Liquid Chromatography Coupled with Solid-phase Extraction

    2011-01-01

    An efficient preparative method was successfully developed for isolation and purification of unstable components from medicinal plant extracts, using a combined method of preparative high performance liquid chro-matography(HPLC) and solid-phase extraction(SPE). The aim of this study was to obtain an effective method with high preparative efficiency and importantly to avoid the transformation of unstable compounds. The preparative HPLC system was based on an LC/MS controlled four-channel autopurification system. The SPE method was performed with a C18 packing material to trap the target compounds and to remove the acidic additive derived from the mobile phase. Using this method, the unstable iridoid glucosides(IGs) as model compounds were successfully isolated and purified from the extract of Hedyotis diffusa Willd. Six IGs(including one new minor IG) and one nucleotide compound were simultaneously obtained, each with a purity of 〉91% as determined by HPLC. The structures of the isolated compounds were identified by UPLC/Q-TOF MS, UV, 1D and/or 2D NMR. It was demonstrated that the combination of preparative HPLC with SPE is a versatile tool for preparative purification of unstable compounds from complex natural products.

  11. Preference of multi-walled carbon nanotube (MWCNT) to single-walled carbon nanotube (SWCNT) and activated carbon for preparing silica nanohybrid pickering emulsion for chemical enhanced oil recovery (C-EOR)

    AfzaliTabar, M. [Department of Chemistry, Islamic Azad University Branch of Tehran North, Tehran (Iran, Islamic Republic of); Alaei, M., E-mail: alaiem@ripi.ir [Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), Tehran (Iran, Islamic Republic of); Ranjineh Khojasteh, R.; Motiee, F. [Department of Chemistry, Islamic Azad University Branch of Tehran North, Tehran (Iran, Islamic Republic of); Rashidi, A.M. [Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), Tehran (Iran, Islamic Republic of)

    2017-01-15

    The aim of this research was to determine the best nano hybrid that can be used as a Pickering emulsion Chemical Enhanced Oil Recovery (C-EOR). Therefore, we have prepared different carbon structures nano hybrids with SiO{sub 2} nano particles with different weight percent using sol-gel method. The as-prepared nano materials were characterized with X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM) and Thermal Gravimetric Analysis (TGA). Pickering emulsions of these nanohybrids were prepared at pH=7 in ambient temperature and with distilled water. Stability of the mentioned Pickering emulsions was controlled for one month. Emulsion phase morphology was investigated using optical microscopic imaging. Evaluation results demonstrated that the best sample is the 70% MWCNT/SiO{sub 2} nanohybrid. Stability of the selected nanohybrid (70% MWCNT/SiO{sub 2} nanohybrid) was investigated by alteration of salinity, pH and temperature. Results showed that the mentioned Pickering emulsion has very good stability at 0.1%, 1% salinity, moderate and high temperature (25 °C and 90 °C) and neutral and alkaline pH (7, 10) that is suitable for the oil reservoirs conditions. The effect of the related nano fluid on the wettability of carbonate rock was investigated by measuring the contact angle and interfacial tension. Results show that the nanofluid could significantly change the wettability of the carbonate rock from oil wet to water wet and can decrease the interfacial tension. Therefore, the 70% MWCNT/SiO{sub 2} nanohybrid Pickering emulsion can be used for Chemical Enhanced Oil Recovery (C-EOR).

  12. Preference of multi-walled carbon nanotube (MWCNT) to single-walled carbon nanotube (SWCNT) and activated carbon for preparing silica nanohybrid pickering emulsion for chemical enhanced oil recovery (C-EOR)

    AfzaliTabar, M.; Alaei, M.; Ranjineh Khojasteh, R.; Motiee, F.; Rashidi, A.M.

    2017-01-01

    The aim of this research was to determine the best nano hybrid that can be used as a Pickering emulsion Chemical Enhanced Oil Recovery (C-EOR). Therefore, we have prepared different carbon structures nano hybrids with SiO 2 nano particles with different weight percent using sol-gel method. The as-prepared nano materials were characterized with X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM) and Thermal Gravimetric Analysis (TGA). Pickering emulsions of these nanohybrids were prepared at pH=7 in ambient temperature and with distilled water. Stability of the mentioned Pickering emulsions was controlled for one month. Emulsion phase morphology was investigated using optical microscopic imaging. Evaluation results demonstrated that the best sample is the 70% MWCNT/SiO 2 nanohybrid. Stability of the selected nanohybrid (70% MWCNT/SiO 2 nanohybrid) was investigated by alteration of salinity, pH and temperature. Results showed that the mentioned Pickering emulsion has very good stability at 0.1%, 1% salinity, moderate and high temperature (25 °C and 90 °C) and neutral and alkaline pH (7, 10) that is suitable for the oil reservoirs conditions. The effect of the related nano fluid on the wettability of carbonate rock was investigated by measuring the contact angle and interfacial tension. Results show that the nanofluid could significantly change the wettability of the carbonate rock from oil wet to water wet and can decrease the interfacial tension. Therefore, the 70% MWCNT/SiO 2 nanohybrid Pickering emulsion can be used for Chemical Enhanced Oil Recovery (C-EOR).

  13. An experimental study of the stable and unstable operation of an LPP gas turbine combustor

    Dhanuka, Sulabh Kumar

    A study was performed to better understand the stable operation of an LPP combustor and formulate a mechanism behind the unstable operation. A unique combustor facility was developed at the University of Michigan that incorporates the latest injector developed by GE Aircraft Engines and enables operation at elevated pressures with preheated air at flow-rates reflective of actual conditions. The large optical access has enabled the use of a multitude of state-of-the-art laser diagnostics such as PIV and PLIF, and has shed invaluable light not only into the GE injector specifically but also into gas turbine combustors in general. Results from Particle Imaging Velocimetry (PIV) have illustrated the role of velocity, instantaneous vortices, and key recirculation zones that are all critical to the combustor's operation. It was found that considerable differences exist between the iso-thermal and reacting flows, and between the instantaneous and mean flow fields. To image the flame, Planar Laser Induced Fluorescence (PLIF) of the formaldehyde radical was successfully utilized for the first time in a Jet-A flame. Parameters regarding the flame's location and structure have been obtained that assist in interpreting the velocity results. These results have also shown that some of the fuel injected from the main fuel injectors actually reacts in the diffusion flame of the pilot. The unstable operation of the combustor was studied in depth to obtain the stability limits of the combustor, behavior of the flame dynamics, and frequencies of the oscillations. Results from simultaneous pressure and high speed chemiluminescence images have shown that the low frequency dynamics can be characterized as flashback oscillations. The results have also shown that the stability of the combustor can be explained by simple and well established premixed flame stability mechanisms. This study has allowed the development of a model that describes the instability mechanism and accurately

  14. Study of shell evolution around the doubly magic $^{208}$Pb via a multinucleon transfer reaction with an unstable beam

    This proposal aims at the study of the neutron-rich region around the doubly-magic nucleus $^{208}$Pb populated via a multinucleon transfer reaction. An unstable $^{94}$Rb beam will be delivered by HIE-ISOLDE at 5.5 MeV$\\cdot$u onto a $^{208}$Pb 13.0 mg/cm$^{2}$ target. The $\\gamma$- rays will be recorded by the MINIBALL $\\gamma$-ray spectrometer. The aim of the experiment is twofold: \\\\ \\\\ i) firstly it will represent the proof of principle that multinucleon transfer reactions with neutron-rich unstable beams is efficient to populate neutron-rich heavy binary partners and represents a competitive method to cold fragmentation \\\\ ii) secondly we aim at populating medium- to high-spin states in $^{212;214}$Pb and $^{208;210}$Hg to elucidate the existence of the 16$^{+}$ isomer in the lead isotopes and at the same time to disentangle the puzzling case of a very low energy 3$^{-}$ state in $^{210}$Hg not described by any nuclear model. \\\\ \\\\ The experimental results will be compared with large-scale shell-model ...

  15. Saturation properties of asymmetric nuclear matter to be obtained from unstable nuclei

    Oyamatsu, Kazuhiro [Aichi Shukutoku Univ., Dept. of Media Production and Theories, Nagakute, Aichi (Japan); Iida, Kei [Institute of Physical and Chemical Research, Wako, Saitama (Japan)

    2002-09-01

    We examine relations among the parameters characterizing the phenomenological equation of state (EOS) of nearly symmetric, uniform nuclear matter near the saturation density from experimental data on radii and masses of stable nuclei. The EOS parameters of interest are the symmetry energy S{sub 0}, the symmetry energy density-derivative coefficient L and the incompressibility K{sub 0} at the normal nuclear density. The calculations of the nuclear properties were performed with a simplified Thomas-Fermi model. We find a constraint on (K{sub 0}, L) values from the slope of the saturation line (the line joining the saturation points of asymmetric matter EOS with fixed proton abundance). A strong correlation between S{sub 0} and L, which was discussed in the Skyrme Hartree-Fock theory for relatively small L values, is found to hold for such larger values as a relativistic mean field theory predicts. In the light of the uncertainties in the (K{sub 0}, L) values, we calculate radii of unstable nuclei as expected to be produced in future facilities. We find that the matter radii depend strongly on L almost independently of K{sub 0}, and that systematic detection of the radii of such nuclei will help to determine the L value. (author)

  16. Reliability of unstable periodic orbit based control strategies in biological systems

    Mishra, Nagender; Singh, Harinder P.; Hasse, Maria; Biswal, B.

    2015-01-01

    Presence of recurrent and statistically significant unstable periodic orbits (UPOs) in time series obtained from biological systems is now routinely used as evidence for low dimensional chaos. Extracting accurate dynamical information from the detected UPO trajectories is vital for successful control strategies that either aim to stabilize the system near the fixed point or steer the system away from the periodic orbits. A hybrid UPO detection method from return maps that combines topological recurrence criterion, matrix fit algorithm, and stringent criterion for fixed point location gives accurate and statistically significant UPOs even in the presence of significant noise. Geometry of the return map, frequency of UPOs visiting the same trajectory, length of the data set, strength of the noise, and degree of nonstationarity affect the efficacy of the proposed method. Results suggest that establishing determinism from unambiguous UPO detection is often possible in short data sets with significant noise, but derived dynamical properties are rarely accurate and adequate for controlling the dynamics around these UPOs. A repeat chaos control experiment on epileptic hippocampal slices through more stringent control strategy and adaptive UPO tracking is reinterpreted in this context through simulation of similar control experiments on an analogous but stochastic computer model of epileptic brain slices. Reproduction of equivalent results suggests that far more stringent criteria are needed for linking apparent success of control in such experiments with possible determinism in the underlying dynamics

  17. Reliability of unstable periodic orbit based control strategies in biological systems

    Mishra, Nagender; Singh, Harinder P. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Hasse, Maria [Institut für Höchstleistungsrechnen, Universität Stuttgart, D-70569 Stuttgart (Germany); Biswal, B. [Cluster Innovation Center, University of Delhi, Delhi 110007 (India); Sri Venkateswara College, University of Delhi, Delhi 110021 (India)

    2015-04-15

    Presence of recurrent and statistically significant unstable periodic orbits (UPOs) in time series obtained from biological systems is now routinely used as evidence for low dimensional chaos. Extracting accurate dynamical information from the detected UPO trajectories is vital for successful control strategies that either aim to stabilize the system near the fixed point or steer the system away from the periodic orbits. A hybrid UPO detection method from return maps that combines topological recurrence criterion, matrix fit algorithm, and stringent criterion for fixed point location gives accurate and statistically significant UPOs even in the presence of significant noise. Geometry of the return map, frequency of UPOs visiting the same trajectory, length of the data set, strength of the noise, and degree of nonstationarity affect the efficacy of the proposed method. Results suggest that establishing determinism from unambiguous UPO detection is often possible in short data sets with significant noise, but derived dynamical properties are rarely accurate and adequate for controlling the dynamics around these UPOs. A repeat chaos control experiment on epileptic hippocampal slices through more stringent control strategy and adaptive UPO tracking is reinterpreted in this context through simulation of similar control experiments on an analogous but stochastic computer model of epileptic brain slices. Reproduction of equivalent results suggests that far more stringent criteria are needed for linking apparent success of control in such experiments with possible determinism in the underlying dynamics.

  18. Neutron optical potentials in unstable nuclei and the equation of state of asymmetric nuclear matter

    Oyamatsu, K.; Iida, K.

    2003-01-01

    Neutron single particle potential is one of the basic macroscopic properties to describe structure and reactions of nuclei in nuclear reactors and in the universe. However, the potential is quite uncertain for unstable nuclei primarily because the equation of state (EOS) of asymmetric nuclear matter is not known well. The present authors studied systematically the empirical EOS of asymmetric nuclear matter using a macroscopic nuclear model; about two hundred EOS's having empirically allowed values of L (symmetry energy density derivative coefficient) and K 0 (incompressibility) were obtained from the fittings to masses and radii of stable nuclei. It was suggested that the L value could be determined from global (Z, A) dependence of nuclear radii. In the present study, the single particle potential is examined assuming kinetic energies of non-interacting Fermi gases. The potential in a nucleus can be calculated easily, once the density distribution is solved using the effective nuclear interaction (EOS). Neutron and proton single particle potentials are calculated systematically for 80 Ni using the two hundred EOS's. It is found that the neutron-proton potential difference has clear and appreciable L dependence, while the potential for each species does not show such simple dependence on L. (author)

  19. Enhanced IMC design of load disturbance rejection for integrating and unstable processes with slow dynamics.

    Liu, Tao; Gao, Furong

    2011-04-01

    In view of the deficiencies in existing internal model control (IMC)-based methods for load disturbance rejection for integrating and unstable processes with slow dynamics, a modified IMC-based controller design is proposed to deal with step- or ramp-type load disturbance that is often encountered in engineering practices. By classifying the ways through which such load disturbance enters into the process, analytical controller formulae are correspondingly developed, based on a two-degree-of-freedom (2DOF) control structure that allows for separate optimization of load disturbance rejection from setpoint tracking. An obvious merit is that there is only a single adjustable parameter in the proposed controller, which in essence corresponds to the time constant of the closed-loop transfer function for load disturbance rejection, and can be monotonically tuned to meet a good trade-off between disturbance rejection performance and closed-loop robust stability. At the same time, robust tuning constraints are given to accommodate process uncertainties in practice. Illustrative examples from the recent literature are used to show effectiveness and merits of the proposed method for different cases of load disturbance. Copyright © 2010. Published by Elsevier Ltd.

  20. The effect of topography on the evolution of unstable disturbances in a baroclinic atmosphere

    Clark, J. H. E.

    1985-01-01

    A two layer spectral quasi-geostrophic model is used to simulate the effects of topography on the equilibria, their stability, and the long term evolution of incipient unstable waves. The flow is forced by latitudinally dependent radiative heating. Dissipation is in the form of Rayleigh friction. An analytical solution is found for the propagating finite amplitude waves which result from baroclinic instability of the zonal winds when topography is absent. The appearance of this solution for wavelengths just longer than the Rossby radius of deformation and disappearance of ultra-long wavelengths is interpreted in terms of the Hopf bifurcation theory. Simple dynamic and thermodynamic criteria for the existence of periodic Rossby solutions are presented. A Floquet stability analysis shows that the waves are neutral. The nature of the form drag instability of high index equilibria is investigated. The proximity of the equilibrium shear to a resonant value is essential for the instability, provided the equilibrium occurs at a slightly stronger shear than resonance.

  1. An efficient identification approach for stable and unstable nonlinear systems using Colliding Bodies Optimization algorithm.

    Pal, Partha S; Kar, R; Mandal, D; Ghoshal, S P

    2015-11-01

    This paper presents an efficient approach to identify different stable and practically useful Hammerstein models as well as unstable nonlinear process along with its stable closed loop counterpart with the help of an evolutionary algorithm as Colliding Bodies Optimization (CBO) optimization algorithm. The performance measures of the CBO based optimization approach such as precision, accuracy are justified with the minimum output mean square value (MSE) which signifies that the amount of bias and variance in the output domain are also the least. It is also observed that the optimization of output MSE in the presence of outliers has resulted in a very close estimation of the output parameters consistently, which also justifies the effective general applicability of the CBO algorithm towards the system identification problem and also establishes the practical usefulness of the applied approach. Optimum values of the MSEs, computational times and statistical information of the MSEs are all found to be the superior as compared with those of the other existing similar types of stochastic algorithms based approaches reported in different recent literature, which establish the robustness and efficiency of the applied CBO based identification scheme. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  2. The height of the atmospheric boundary layer during unstable conditions

    Gryning, S.E.

    2005-11-01

    The height of the convective atmospheric boundary layer, also called the mixed-layer, is one of the fundamental parameters that characterise the structure of the atmosphere near the ground. It has many theoretical and practical applications such as the prediction of air pollution concentrations, surface temperature and the scaling of turbulence. However, as pointed out by Builtjes (2001) in a review paper on Major Twentieth Century Milestones in Air Pollution Modelling and Its Application, the weakest point in meteorology data is still the determination of the height of the mixed-layer, the so-called mixing height. A simple applied model for the height of the mixed-layer over homogeneous terrain is suggested in chapter 2. It is based on a parameterised budget for the turbulent kinetic energy. In the model basically three terms - the spin-up term and the production of mechanical and convective turbulent kinetic energy - control the growth of the mixed layer. The interplay between the three terms is related to the meteorological conditions and the height of the mixed layer. A stable layer, the so-called entrainment zone, which is confined between the mixed layer and the free air above, caps the mixed layer. A parameterisation of the depth of the entrainment zone is also suggested, and used to devise a combined model for the height of the mixed layer and the entrainment zone. Another important aspect of the mixed layer development exists in coastal areas where an internal boundary layer forms downwind from the coastline. A model for the growth of the internal boundary layer is developed in analogy with the model for mixed layer development over homogeneous terrain. The strength of this model is that it can operate on a very fine spatial resolution with minor computer resources. Chapter 3 deals with the validation of the models. It is based in parts on data from the literature, and on own measurements. For the validation of the formation of the internal boundary layer

  3. Stable or unstable tear of the anterior cruciate ligament of the knee: an MR diagnosis?

    Dyck, Pieter van; Gielen, Jan L.; Parizel, Paul M. [University Hospital Antwerp and University of Antwerp, Department of Radiology, Edegem (Belgium); Vanhoenacker, Filip M. [University Hospital Antwerp and University of Antwerp, Department of Radiology, Edegem (Belgium); AZ St-Maarten Duffel/Mechelen, Department of Radiology, Duffel (Belgium); Wouters, Kristien [University Hospital Antwerp and University of Antwerp, Department of Scientific Coordination and Biostatistics, Edegem (Belgium); Dossche, Lieven [University Hospital Antwerp and University of Antwerp, Department of Orthopedics, Edegem (Belgium)

    2012-03-15

    To determine the usefulness of magnetic resonance (MR) imaging to distinguish stable from unstable tears of the anterior cruciate ligament (ACL) of the knee. MR images of 97 patients with surgically confirmed ACL tear were retrospectively reviewed. According to arthroscopic and clinical examination, these patients had 36 stable and 61 unstable (9 partial and 52 complete) ACL tears. MR images were interpreted by two blinded reviewers and scored with respect to previously reported primary and secondary MR signs of ACL injury. Based on a comprehensive assessment of all the MR findings, ACLs were categorized as being stable or unstable. MR accuracy was calculated considering only primary MR signs and considering both primary and secondary MR signs of ACL injury, separately. Accuracy of each individual primary and secondary MR sign was calculated. Considering only primary MR signs, sensitivity, specificity, and accuracy of MR were 77, 92, and 82%, respectively. Considering both primary and secondary MR signs, sensitivity, specificity, and accuracy of MR were 59, 81, and 67%, respectively. Of all MR signs, discontinuity and abnormal orientation had highest test accuracy (79 and 87%, respectively). Anterior tibial translation, uncovering of the posterior horn of the lateral meniscus, and hyperbuckled PCL were only seen in unstable ACLs (specificity 100%), but these secondary findings had low sensitivity (23%). Bone contusion around the lateral knee compartment was seen in both unstable and stable ACLs (accuracy 64%). Previously reported MR imaging signs do not allow accurate distinction between clinically stable and unstable ACL injuries. Anterior tibial translation, uncovering of the posterior horn of the lateral meniscus, and hyperbuckled PCL, if present, are helpful signs in the diagnosis of an unstable tear. The presence of bone marrow edema around the lateral knee compartment is not predictive of ACL insufficiency. (orig.)

  4. Nonlinear Analysis of an Unstable Bench Press Bar Path and Muscle Activation.

    Lawrence, Michael A; Leib, Daniel J; Ostrowski, Stephanie J; Carlson, Lara A

    2017-05-01

    Lawrence, MA, Leib, DJ, Ostrowski, SJ, and Carlson, LA. Nonlinear analysis of an unstable bench press bar path and muscle activation. J Strength Cond Res 31(5): 1206-1211, 2017-Unstable resistance exercises are typically performed to improve the ability of stabilizing muscles to maintain joint integrity under a load. The purpose of this study was to examine the effects of an unstable load (as provided by a flexible barbell and a load suspended by elastic bands) on the bar path, the primary musculature, and stabilizing musculature while bench pressing using nonlinear analyses. Fifteen resistance-trained men (age 24.2 ± 2.7 years, mass 84.1 ± 12.0 kg, height 1.77 ± 0.05 m, 9.9 ± 3.4 years of lifting experience, and bench press 1 repetition maximum (RM) 107.5 ± 25.9 kg) volunteered for this study. Subjects pressed 2 sets of 5 repetitions in both stable (total load 75% 1RM) and unstable (total load 60% 1RM) conditions using a standard barbell and a flexible Earthquake bar, respectively. Surface electromyography was used to detect muscle activity of primary movers (pectoralis major, anterior deltoid, and triceps) and bar stabilizing musculature (latissimus dorsi, middle and posterior deltoid, biceps brachii, and upper trapezius). During the unstable condition, the bar moved in more ways and was less predictable in the mediolateral and anteroposterior directions. However, the muscle activation patterns of all muscles were more constrained with the unstable barbell. These findings suggest that the unstable condition was more challenging to control, but subjects controlled the instability by contracting their muscles in a more stable pattern or "staying tight" throughout the exercise.

  5. Effect of an Unstable Load on Primary and Stabilizing Muscles During the Bench Press.

    Ostrowski, Stephanie J; Carlson, Lara A; Lawrence, Michael A

    2017-02-01

    Ostrowski, SJ, Carlson, LA, and Lawrence, MA. Effect of an unstable load on primary and stabilizing muscles during the bench press. J Strength Cond Res 31(2): 430-434, 2017-Unstable resistance exercises are performed to increase activity of stabilizing muscles. The premise is that this increase in activity will yield greater strength gains than traditional resistance exercises. The purpose of this study was to determine if an unstable load increases muscle activity of stabilizing muscles during a bench press as compared with a standard bench press with a typical load. Fifteen resistance-trained males (age 24.2 ± 2.7 years, mass 84.8 ± 12.0 kg, height 1.77 ± 0.05 m, weight lifting experience 9.9 ± 3.4 years, and bench press 1 repetition maximum [1RM] 107.5 ± 25.9 kg) volunteered for this study. Subjects pressed 2 sets of 5 repetitions in both stable (75% 1RM) and unstable (60% 1RM) conditions using a standard barbell and a flexible Earthquake bar, respectively. Surface electromyography was used to detect muscle activity of primary movers (pectoralis major, anterior deltoid, and triceps) and stabilizing musculature (latissimus dorsi, middle and posterior deltoid, biceps brachii, and upper trapezius). Muscle activity was compared using a multivariate analysis of variance to determine significant (p ≤ 0.05) phase and condition differences. The right and left biceps and the left middle deltoid were significantly more active in the unstable condition. Some of the stabilizing muscles were found to be significantly more active in the unstable condition with 15% less weight. Therefore, bench pressing with an unstable load appears promising in activating stabilizing musculature compared with pressing a typical barbell.

  6. Unstable Modes and Order Parameters of Bistable Signaling Pathways at Saddle-Node Bifurcations: A Theoretical Study Based on Synergetics

    Till D. Frank

    2016-01-01

    Full Text Available Mathematical modeling has become an indispensable part of systems biology which is a discipline that has become increasingly popular in recent years. In this context, our understanding of bistable signaling pathways in terms of mathematical modeling is of particular importance because such bistable components perform crucial functions in living cells. Bistable signaling pathways can act as switches or memory functions and can determine cell fate. In the present study, properties of mathematical models of bistable signaling pathways are examined from the perspective of synergetics, a theory of self-organization and pattern formation founded by Hermann Haken. At the heart of synergetics is the concept of so-called unstable modes or order parameters that determine the behavior of systems as a whole close to bifurcation points. How to determine these order parameters for bistable signaling pathways at saddle-node bifurcation points is shown. The procedure is outlined in general and an explicit example is worked out in detail.

  7. Crisis and unstable dimension variability in the bailout embedding ...

    The complex dynamics of aerosols in the atmosphere, plankton in oceans, and impurity transport in industrial applications are a few of the varied contexts in which impurity dynamics is of interest. The fluid flow, which is the base flow, can be modeled by a two-dimensional in- compressible flow and the Lagrangian dynamics ...

  8. Relationship between the serologic status of helicobacter pylori with the presence of unstable angina

    Alavi, S.M.; Adel, S. M. H.; Rajabzadeh, A.

    2008-01-01

    To determine whether unstable angina is co-related to seropositivity to chronic Helicobacter pylori (HP) infection. It is a case control, descriptive study conducted at CCU in Razi Hospital in Ahwaz a city southwest Iran, from 2004 to 2005. We measured serum HP- lgG levels of participants in CCU in a hospital. Blood samples were drawn during study period from 96 patients (mean age 56 years) with Unstable Angina (UA) according to American Heart Association criteria and from 96 participants free of cardiovascular disease (mean age 58 years) and stored at 20 degree C. Serology results were studied in relation to UA. Using chi squared test, odds ratios (OR) and 95% confidence intervals (CI) were calculated, adjusting for age, gender, and established risk factors. Seventy nine (82.3%) of patients with unstable angina and 55(61.1%) in the control group presented a positive anti HP-lgG. Odds ratio was 3 with 95% CI: 1.9 to 4.3. There was significant relation between HP-lgG positivity and unstable angina (P 0.05). Our study revealed relationship between seropositivity of HP-lgG and unstable angina. (author)

  9. Force production during squats performed with a rotational resistance device under stable versus unstable conditions.

    Moras, Gerard; Vázquez-Guerrero, Jairo

    2015-11-01

    [Purpose] Force production during a squat action on a rotational resistance device (RRD) under stable and unstable conditions. [Subjects and Methods] Twenty-one healthy males were asked to perform six sets of six repetitions of squats on an RRD on either stable or unstable surfaces. The stable and unstable sets were performed on different days. Muscular outputs were obtained from a linear encoder and a strain gauge fixed to a vest. [Results] Overall, the results showed no significant differences for any of the dependent variables across exercise modes. Forcemean outputs were higher in the concentric phase than in the eccentric phase for each condition, but there were no differences in velocity, time or displacement. The forcepeak was similar in the eccentric and concentric phases of movement under both stable and unstable conditions. There were no significant differences in forcemean between sets per condition or between conditions. [Conclusion] These results suggest that performing squats with a RRD achieves similar forcemean and forcepeak under stable and unstable conditions. The forcepeak produced is also similar in concentric and eccentric phases.

  10. Muscular outputs during dynamic bench press under stable versus unstable conditions.

    Koshida, Sentaro; Urabe, Yukio; Miyashita, Koji; Iwai, Kanzunori; Kagimori, Aya

    2008-09-01

    Previous studies have suggested that resistance training exercise under unstable conditions decreases the isometric force output, yet little is known about its influence on muscular outputs during dynamic movement. The objective of this study was to investigate the effect of an unstable condition on power, force, and velocity outputs during the bench press. Twenty male collegiate athletes (mean age, 21.3 +/- 1.5 years; mean height, 167.7 +/- 7.7 cm; mean weight, 75.9 +/- 17.5 kg) participated in this study. Each subject attempted 3 sets of single bench presses with 50% of 1 repetition maximum (1RM) under a stable condition with a flat bench and an unstable condition with a Swiss ball. Acceleration data were obtained with an accelerometer attached to the center of a barbell shaft, and peak outputs of power, force, and velocity were computed. Although significant loss of the peak outputs was found under the unstable condition (p velocity outputs, compared with previous findings. Such small reduction rates of muscular outputs may not compromise the training effect. Prospective studies are necessary to confirm whether the resistance training under an unstable condition permits the improvement of dynamic performance and trunk stability.

  11. J-integral evaluation and stability analysis in the unstable ductile fracture

    Miyoshi, Toshiro; Yoshida, Yuichiro; Shiratori, Masaki.

    1984-01-01

    Concerning unstable ductile fracture, which is an important problem on the structural stability of line pipes, nuclear reactor piping and so on, the research on fracture mechanics parameters which control the beginning of the stable growth and unstable growth of cracks attracts interest. At present, as the parameters, the T-modulus based on J-integral crack tip opening angle, crack opening angle averaged over crack developing part, plastic work coefficient and so on have been proposed. The research on the effectiveness and inter-relation of these parameters is divided into generation phase and application phase, and by these researches, it was reported that all T-modulus, CTOA and COA took almost constant values in relation to crack development, except initial transition period. In order to decide which parameter is most appropriate, the detailed analysis is required. In this study, the analysis of unstable ductile fracture of a central crack test piece and a small tensile test piece was carried out by finite element method, and the evaluation of J-integral in relation to crack development, J-integral resistance value when COA is assumed to be a constant, the form of an unstable fracture occurring point and the compliance dependence were examined. The method of analysis, the evaluation of J-integral, J-integral resistance value, unstable fracture occurring point and stability diagram are described. (Kako, I.)

  12. The use of unstable chromosome aberrations and micronuclei in the individual biomonitoring: a comparative study

    Fernandes, Thiago de Salazar e

    2005-02-01

    Biodosimetry is based on the investigation of radioinduced biological effects in order to correlate them with the absorbed dose. The quantification of unstable chromosome aberrations and micronuclei, in peripheral blood lymphocytes, are two methods commonly used in biodosimetry. In this context, the aim of this research was to compare these methods in the biomonitoring of health care professionals occupationally exposed to ionizing radiation. In parallel, the technique of C-banding was evaluated for quality control of unstable chromosome aberrations analyses. Thus, samples of peripheral blood from health care professionals of three hospitals from Recife (Brazil) were collected, and the lymphocytes cultures were carried out based on the cytogenetic classical technique. It was pointed out that analysis of micronuclei is faster than the unstable chromosome aberrations ones, which suggests the use of the former in preliminary evaluation in cases of suspected accidental exposure. C-banding technique was efficient, as confirmatory test, in the identification of dicentrics and rings during the analyses of unstable chromosome aberrations, being able to be applied in the quality control in biodosimetry. The comparison between the individual work conditions with the frequencies of unstable aberrations and micronuclei obtained from cytogenetic analysis, resulted in the change of behavior of the professionals involved in this research, with a better observance of the radioprotection standards. (author)

  13. Soleus and lateral gastrocnemius H-reflexes during standing with unstable footwear.

    Friesenbichler, Bernd; Lepers, Romuald; Maffiuletti, Nicola A

    2015-05-01

    Unstable footwear has been shown to increase lower extremity muscle activity, but the reflex response to perturbations induced by this intervention is unknown. Twenty healthy subjects stood in stable and unstable footwear conditions (presented randomly) while H-reflex amplitude and background muscle activity were measured in the soleus and lateral gastrocnemius (LG) muscles. Wearing unstable footwear resulted in larger H-reflexes (normalized to the maximal M-wave) for the LG (+12%; P = 0.025), but not for the soleus (+4%; P > 0.05). Background activity of both muscles was significantly higher in the unstable condition. The H-reflex facilitation observed with unstable footwear was unexpected, as challenging postural conditions usually result in reflex depression. Increased muscle activity, decreased presynaptic inhibition, and/or more forward postural position may have (over-)compensated the expected reflex depression. Differences between LG and soleus H-reflex modulation may be due to diverging motor unit recruitment thresholds. © 2015 Wiley Periodicals, Inc.

  14. The exact rogue wave recurrence in the NLS periodic setting via matched asymptotic expansions, for 1 and 2 unstable modes

    Grinevich, P. G.; Santini, P. M.

    2018-04-01

    The focusing Nonlinear Schrödinger (NLS) equation is the simplest universal model describing the modulation instability (MI) of quasi monochromatic waves in weakly nonlinear media, the main physical mechanism for the generation of rogue (anomalous) waves (RWs) in Nature. In this paper we investigate the x-periodic Cauchy problem for NLS for a generic periodic initial perturbation of the unstable constant background solution, in the case of N = 1 , 2 unstable modes. We use matched asymptotic expansion techniques to show that the solution of this problem describes an exact deterministic alternate recurrence of linear and nonlinear stages of MI, and that the nonlinear RW stages are described by the N-breather solution of Akhmediev type, whose parameters, different at each RW appearance, are always given in terms of the initial data through elementary functions. This paper is motivated by a preceding work of the authors in which a different approach, the finite gap method, was used to investigate periodic Cauchy problems giving rise to RW recurrence.

  15. Evaluation of ΔGsub(f) values for unstable compounds: a Fortran program for the calculation of ternary phase equilibria

    Throop, G.J.; Rogl, P.; Rudy, E.

    1978-01-01

    A Fortran IV program was set up for the calculation of phase equilibria and tieline distributions in ternary systems of the type: transition metal-transition metal-nonmetal (interstitial type of solid solutions). The method offers the possibility of determining the thermodynamic values for unstable compounds through their influence upon ternary phase equilibria. The variation of the free enthalpy of formation of ternary solid solutions is calculated as a function of nonmetal content, thus describing the actual curvature of the phase boundaries. The integral and partial molar free enthalpies of formation of binary nonstoichiometric compounds and of phase solutions are expressed as analytical functions of the nonmetal content within their homogeneity range. The coefficient of these analytical expressions are obtained by the use either of the Wagner-Schottky vacancy model or polynomials second order in composition (parabolic approach). The free energy of formation, ΔGsub(f) has been calculated for the systems Ti-C, Zr-C, and Ta-C. Calculations of the ternary phase equilibria yielded the values for ΔGsub(f) for the unstable compounds Ti 2 C at 1500 0 C and Zr 2 C at 1775 0 C of -22.3 and 22.7 kcal g atom metal respectively. These values were used for the calculation of isothermal sections within the ternary systems Ti-Ta-C (at 1500 0 C) and Zr-Ta-C (at 1775 0 C). The ideal case of ternary phase solutions is extended to regular solutions. (author)

  16. A framework for identifying plant species to be used as 'ecological engineers' for fixing soil on unstable slopes.

    Ghestem, Murielle; Cao, Kunfang; Ma, Wenzhang; Rowe, Nick; Leclerc, Raphaëlle; Gadenne, Clément; Stokes, Alexia

    2014-01-01

    Major reforestation programs have been initiated on hillsides prone to erosion and landslides in China, but no framework exists to guide managers in the choice of plant species. We developed such a framework based on the suitability of given plant traits for fixing soil on steep slopes in western Yunnan, China. We examined the utility of 55 native and exotic species with regard to the services they provided. We then chose nine species differing in life form. Plant root system architecture, root mechanical and physiological traits were then measured at two adjacent field sites. One site was highly unstable, with severe soil slippage and erosion. The second site had been replanted 8 years previously and appeared to be physically stable. How root traits differed between sites, season, depth in soil and distance from the plant stem were determined. Root system morphology was analysed by considering architectural traits (root angle, depth, diameter and volume) both up- and downslope. Significant differences between all factors were found, depending on species. We estimated the most useful architectural and mechanical traits for physically fixing soil in place. We then combined these results with those concerning root physiological traits, which were used as a proxy for root metabolic activity. Scores were assigned to each species based on traits. No one species possessed a suite of highly desirable traits, therefore mixtures of species should be used on vulnerable slopes. We also propose a conceptual model describing how to position plants on an unstable site, based on root system traits.

  17. A framework for identifying plant species to be used as 'ecological engineers' for fixing soil on unstable slopes.

    Murielle Ghestem

    Full Text Available Major reforestation programs have been initiated on hillsides prone to erosion and landslides in China, but no framework exists to guide managers in the choice of plant species. We developed such a framework based on the suitability of given plant traits for fixing soil on steep slopes in western Yunnan, China. We examined the utility of 55 native and exotic species with regard to the services they provided. We then chose nine species differing in life form. Plant root system architecture, root mechanical and physiological traits were then measured at two adjacent field sites. One site was highly unstable, with severe soil slippage and erosion. The second site had been replanted 8 years previously and appeared to be physically stable. How root traits differed between sites, season, depth in soil and distance from the plant stem were determined. Root system morphology was analysed by considering architectural traits (root angle, depth, diameter and volume both up- and downslope. Significant differences between all factors were found, depending on species. We estimated the most useful architectural and mechanical traits for physically fixing soil in place. We then combined these results with those concerning root physiological traits, which were used as a proxy for root metabolic activity. Scores were assigned to each species based on traits. No one species possessed a suite of highly desirable traits, therefore mixtures of species should be used on vulnerable slopes. We also propose a conceptual model describing how to position plants on an unstable site, based on root system traits.

  18. Variability of the groundwater sulfate concentration in fractured rock slopes: a tool to identify active unstable areas

    S. Binet

    2009-12-01

    Full Text Available Water chemical analysis of 100 springs from the Orco and the Tinée valleys (Western Italy and Southern France and a 7 year groundwater chemistry monitoring of the 5 main springs were performed. All these springs drain from crystalline rock slopes. Some of these drain from currently active gravitational slope deformations.

    All groundwaters flowing through presently unstable slopes show anomalies in the sulfate concentrations compared to stable aquifers. Particularly, an increase of sulfate concentrations was observed repeatedly after each of five consecutive landslides on the La Clapière slope, thus attesting to the mechanical deformations are at the origin of this concentration change. Significant changes in the water chemistry are produced even from slow (mm/year and low magnitude deformations of the geological settings.

    Pyrite nuclei in open fractures were found to be coated by iron oxides. This suggests that the increase of dissolved sulfate relates to oxidative dissolution of Pyrite. Speciation calculations of Pyrite versus Gypsum confirmed that observed changes in the sulfate concentrations is predominantly provided from Pyrite. Calculated amounts of dissolved minerals in the springs water was obtained through inverse modelling of the major ion water analysis data. It is shown that the concentration ratio of calculated dissolved Pyrite versus calculated dissolved gneiss rock allows us to unambiguously distinguish water from stable and unstable areas. This result opens an interesting perspective for the follow-up of sliding or friction dynamic in landslides or in (a seismic faults.

  19. Unified studies of structure and reactions in light unstable nuclei

    Ito Makoto

    2016-01-01

    Full Text Available The generalized two-center cluster model (GTCM, which can treat covalent, ionic and atomic configurations in general systems with two inert cores plus valence nucleons, is formulated in the basis of the microscopic cluster model. In this model, the covalent configurations constructed by the molecular orbital (MO method and the atomic (or ionic configuration obtained by the valence bonding (VB method can be described in a consistent manner. GTCM is applied to the light neutron-rich system, 10,12Be = α + α + XN (X = 2,4, and the unified studies of the structural changes and the reaction problem are performed. In the structure study, the calculated energy levels are characterized in terms of the chemical bonding like structures, such as the covalent MO or ionic VB structures. The chemical bonding structures changes from level to level within a small energy interval. In the unbound region, the structure problem with the total system of α + α + XN and the reaction problem, induced by the collision of an asymptotic VB state of α+6,8He, are combined by GTCM. The properties of unbound resonant states are discussed in a close connection to the reaction mechanism, and some enhancement factors originated from the properties of the intrinsic states are predicted in the reaction observables. The unified calculation of the structures and the reactions is applied to the Coulomb shift problem in the mirror system, such the 10Be and 10C nuclei. The Coulomb displacement energy of the mirror systems are discussed.

  20. Spin correlations in the decays of two unstable particles

    Lednicky, R.; Lyuboshitz, V.L.; Lyuboshitz, V.V.

    2004-01-01

    The general theory of angular correlations in the decays of two arbitrarily polarized particles (resonances), connected with the two-particle spin correlations, is constructed. In particular, the angular correlations between the flight directions of the decay, products of two identical particles with close momenta are considered in the model of independent particle sources emitting unpolarized particles with a nonzero spin. It is established that in this case the angular correlations reflect the spin correlations caused by the effects of quantum statistics and final-state interaction. (author)

  1. Production of spin-polarized unstable nuclei by using polarized electron capture process

    Shimizu, S.

    1998-01-01

    Measurements of emitted radiation from spin polarized nuclei are used to get information on electromagnetic moment of ground state unstable nuclei together with spin or parity state of excited states of their decayed (daughter) nuclei. These data are known to be useful for experimental investigation into the structure of unstable nuclei far from the stability line. The present study aims to establish a general method applicable to 11 Be and 16 N nuclei. To produce spin polarization, a new method in which the electron spin polarization of Rb is firstly produced by laser pumping, then the electron is transferred to the unstable nuclear beam (RNB) when they passes through the Rb vapor is proposed. Finally the polarized RNB will be implanted into superfluid helium to remain with a long spin-relaxation time. Future experimental set up for the above measurement adopted in the available radioactive nuclear beam facilities is briefly described. (Ohno, S.)

  2. Effects of constant immigration on the dynamics and persistence of stable and unstable Drosophila populations

    Dey, Snigdhadip; Joshi, Amitabh

    2013-01-01

    Constant immigration can stabilize population size fluctuations but its effects on extinction remain unexplored. We show that constant immigration significantly reduced extinction in fruitfly populations with relatively stable or unstable dynamics. In unstable populations with oscillations of amplitude around 1.5 times the mean population size, persistence and constancy were unrelated. Low immigration enhanced persistence without affecting constancy whereas high immigration increased constancy without enhancing persistence. In relatively stable populations with erratic fluctuations of amplitude close to the mean population size, both low and high immigration enhanced persistence. In these populations, the amplitude of fluctuations relative to mean population size went down due to immigration, and their dynamics were altered to low-period cycles. The effects of immigration on the population size distribution and intrinsic dynamics of stable versus unstable populations differed considerably, suggesting that the mechanisms by which immigration reduced extinction risk depended on underlying dynamics in complex ways. PMID:23470546

  3. Interaction effects on the unstable discharge-energy characteristic of pump-turbine in pump mode

    Tao, R.; Xiao, R. F.; Yang, W.; Liu, W. C.

    2013-12-01

    For a pump-turbine, unstable discharge-energy characteristic is an important factor for operating stability. In this study, the rotor-stator interaction effects on the pump-turbine which has the unstable discharge-energy characteristic has been studied. A series of transient CFD simulations under different discharge conditions have been conducted. Through the contrast between the simulations and experiments, it is found out that the energy decline is strongly affected by the flow loss in the adjustable vane. More importantly, the magnitude and direction of fluid flowing into the adjustable vane are varying with the impeller rotating. Disordered flow structure occurs in the adjustable vane and causes the energy losses due to the interaction effects. Based on this study, improvements on the flow uniformity at impeller outlet will help us to solve the unstable discharge-energy problem.

  4. Energy harvesting by dynamic unstability and internal resonance for piezoelectric beam

    Lan, Chunbo; Qin, Weiyang, E-mail: 353481781@qq.com; Deng, Wangzheng [Department of Engineering Mechanics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2015-08-31

    We investigated the energy harvesting of a vertical beam with tip mass under vertical excitations. We applied dynamic unstability and internal resonance to improve the efficiency of harvesting. The experiments of harmonic excitation were carried out. Results show that for the beam there exist internal resonances in the dynamically unstable and the buckling bistable cases. The dynamic unstability is a determinant for strong internal resonance or mode coupling, which can be used to create a large output from piezoelectric patches. Then, the experiments of stochastic excitation were carried out. Results prove that the internal resonance or mode coupling can transfer the excitation energy to the low order modes, mainly the first and the second one. This can bring about a large output voltage. For a stochastic excitation, it is proved that there is an optimal weight of tip mass for realizing internal resonance and producing large outputs.

  5. Detection of unstable angina by /sup 99m/technetium pyrophosphate myocardial scintigraphy

    Abdulla, A.M.; Canedo, M.I.; Cortez, B.C.; McGinnis, K.D.; Wilhelm, S.K.

    1976-01-01

    /sup 99m/Technetium stannous pyrophosphate has been shown to accumulate in acutely infarcted myocardium. To determine if the isotope is also taken up by severely ischemic, but not necrotic myocardium, we performed myocardial scintigraphic studies in 17 patients with chest pains. Seven of the patients satisfied conventional clinical, electrocardiographic, and laboratory criteria for the diagnosis of unstable angina and showed no electrocardiographic or enzymatic evidence of myocardial necrosis. Five of these seven patients with unstable angina demonstrated abnormal localized patterns, and one showed a borderline picture. Myocardial scintiscans were normal in all of a control group of ten patients with stable angina. Thus, scanning with /sup 99m/technetium stannous pyrophosphate is shown to be of value in the objective demonstration of myocardial abnormality in unstable angina

  6. Self-consistent relativistic QRPA studies of soft modes and spin-isospin resonances in unstable nuclei

    Paar, N.; Niksic, T.; Marketin, T.; Vretenar, D.; Ring, P.

    2005-01-01

    The excitation phenomena in unstable nuclei are investigated in the framework of the relativistic quasiparticle random-phase approximation (RQRPA) in the relativistic Hartree-Bogolyubov model (RHB) which is extended to include effective interactions with explicit density-dependent meson-nucleon couplings. The properties of the pygmy dipole resonance (PDR) are examined in 132 Sn and within isotopic chains, showing that already at moderate proton-neutron asymmetry the PDR peak energy is located above the neutron emission threshold. A method is suggested for determining the size of the neutron skin within an isotopic chain, based on the measurement of the excitation energies of the Gamow-Teller resonance relative to the isobaric analog state. In addition, for the first time the relativistic RHB+RQRPA model, with tensor ω meson-nucleon couplings, is employed in calculations of β-decay half-lives of nuclei of the relevance for the r-process. (orig.)

  7. Self-consistent relativistic QRPA studies of soft modes and spin-isospin resonances in unstable nuclei

    Paar, N. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); University of Zagreb, Physics Department, Faculty of Science (Croatia); University of Washington, Institute for Nuclear Theory, Seattle (United States); Niksic, T. [University of Zagreb, Physics Department, Faculty of Science (Croatia); University of Washington, Institute for Nuclear Theory, Seattle (United States); Marketin, T.; Vretenar, D. [University of Zagreb, Physics Department, Faculty of Science (Croatia); Ring, P. [Physik-Department der Technischen Universitaet Muenchen, Garching (Germany)

    2005-09-01

    The excitation phenomena in unstable nuclei are investigated in the framework of the relativistic quasiparticle random-phase approximation (RQRPA) in the relativistic Hartree-Bogolyubov model (RHB) which is extended to include effective interactions with explicit density-dependent meson-nucleon couplings. The properties of the pygmy dipole resonance (PDR) are examined in {sup 132}Sn and within isotopic chains, showing that already at moderate proton-neutron asymmetry the PDR peak energy is located above the neutron emission threshold. A method is suggested for determining the size of the neutron skin within an isotopic chain, based on the measurement of the excitation energies of the Gamow-Teller resonance relative to the isobaric analog state. In addition, for the first time the relativistic RHB+RQRPA model, with tensor {omega} meson-nucleon couplings, is employed in calculations of {beta}-decay half-lives of nuclei of the relevance for the r-process. (orig.)

  8. A comparison of locked versus nonlocked Enders rods for length unstable pediatric femoral shaft fractures.

    Ellis, Henry Bone; Ho, Christine A; Podeszwa, David A; Wilson, Philip L

    2011-12-01

    Stainless steel flexible Enders rods have been used for intramedullary fixation of pediatric femur fractures with good success. Despite intraoperative anatomic alignment, length unstable femur fractures can present postoperatively with fracture shortening. The purpose of this study was to review all length unstable pediatric femoral shaft fractures in which Enders rods were used and compare those that were locked to those that were not locked. A retrospective clinical and radiographic review of all patients at a single institution undergoing flexible intramedullary fixation for length unstable femoral shaft fractures from 2001 to 2008. A length unstable fracture was defined as either a comminuted fracture or a spiral fracture longer than twice the diameter of the femoral shaft. A total of 107 length unstable femoral shaft fractures fixed with Enders rods were identified, of which 37 cases (35%) had both Enders rods "locked" through the eyelet in the distal femur with a 2.7 mm fully threaded cortical screw. Patient demographics, clinical course, complications, fracture characteristics, and radiographic outcomes were compared for the locked and nonlocked groups. There were no statistical differences between the groups in demographic data, operative variables, fracture pattern, fracture location, time to union, femoral alignment, or major complications. Shortening of the femur and nail migration measured at 1 to 6 weeks postoperatively was significantly greater for the nonlocked cases. The medial and lateral locked Enders rods moved 1.3 and 1.9 mm, respectively, and the unlocked Enders each moved 12.1 mm (P < 0.05). At final follow-up there were significantly more (P < 0.05) clinical complaints in nonlocked group, including limp, clinical shortening, and painful palpable rods. Locking Enders rods for length unstable pediatric fractures is an excellent option to prevent shortening and resulted in no additional complications, added surgical time, or increased blood loss

  9. Study of the X-Ray Diagnosis of Unstable Pelvic Fracture Displacements in Three-Dimensional Space and its Application in Closed Reduction.

    Shi, Chengdi; Cai, Leyi; Hu, Wei; Sun, Junying

    2017-09-19

    ABSTRACTS Objective: To study the method of X-ray diagnosis of unstable pelvic fractures displaced in three-dimensional (3D) space and its clinical application in closed reduction. Five models of hemipelvic displacement were made in an adult pelvic specimen. Anteroposterior radiographs of the pelvis were analyzed in PACS. The method of X-ray diagnosis was applied in closed reductions. From February 2012 to June 2016, 23 patients (15 men, 8 women; mean age, 43.4 years) with unstable pelvic fractures were included. All patients were treated by closed reduction and percutaneous cannulate screw fixation of the pelvic ring. According to Tile's classification, the patients were classified into type B1 in 7 cases, B2 in 3, B3 in 3, C1 in 5, C2 in 3, and C3 in 2. The operation time and intraoperative blood loss were recorded. Postoperative images were evaluated by Matta radiographic standards. Five models of displacement were made successfully. The X-ray features of the models were analyzed. For clinical patients, the average operation time was 44.8 min (range, 20-90 min) and the average intraoperative blood loss was 35.7 (range, 20-100) mL. According to the Matta standards, 7 cases were excellent, 12 cases were good, and 4 were fair. The displacements in 3D space of unstable pelvic fractures can be diagnosed rapidly by X-ray analysis to guide closed reduction, with a satisfactory clinical outcome.

  10. Stable and unstable crack growth in Type 304 stainless steel plate

    Yagawa, G.

    1984-01-01

    Experimental and theoretical results on stable as well as unstable fractures for Type 304 stainless steel plates with a central crack subjected to tension force are given. In the experiment using a testing machine with a special spring for high compliance, the transition points from the stable to the unstable crack growth are observed and comparisons are made between the test results and the finite element solutions. A round robin calculation for the elastic-plastic stable crack growth using one of the specimens mentioned above is also given. (orig.)

  11. Utilization of Point Clouds Characteristics in Interpretation and Evaluation Geophysical Resistivity Surveying of Unstable Running Block

    Marcel Brejcha

    2016-05-01

    Full Text Available Close to human residences the places often abound where anthropogenic activity and external factors cause their changes. The changes can often influence their inhabitants’ life thanks to incipient dangerous places. The project of successful design of measures to ensure stability of unstable running blocks depends on chosen approaches and primary resource preparation. Utilization of modern technologies in their taking and processing is required nowadays. The paper describes the taking and processing of data for project of solution „Stabilization of unstable running block“ in a municipal settled part with efficient utilization of unusual method of processing of geophysical resistivity method.

  12. Circumferential wires as a supplement to intramedullary nailing in unstable trochanteric hip fractures

    Ban, Ilija; Birkelund, Lasse; Palm, Henrik

    2012-01-01

    Fixation of unstable trochanteric fractures is challenging. Application of a circumferential wire may facilitate bone contact and avoid postoperative fracture displacement. However, the use of circumferential wires remains controversial due to possible disturbance of the blood supply to the under......Fixation of unstable trochanteric fractures is challenging. Application of a circumferential wire may facilitate bone contact and avoid postoperative fracture displacement. However, the use of circumferential wires remains controversial due to possible disturbance of the blood supply...... to the underlying bone. We evaluated the results of applied circumferential wires, concentrating mainly on complications and reoperations....

  13. Unstable angina pectoris: the results of intracoronary administration of fibrinolytic agents

    Gratsianskij, N.A.; Panchenko, E.P.; Agapov, A.A.; Logutov, Yu.A.; Vladimirov, S.S.

    1986-01-01

    Intracoronary thrombolytic infusions were used in 10 patients with unstable angina and high risk of myocardial infarction (MI). Streptokinase (500.000 units per hour) was used in 9 patients, and urokinase, in one. Vascular recanalization was achieved in 4 cases where angiografhy, showed coronary arterial occlusion by a thrombus. Myocardial infarction developed in 8 patients (large-focal in 6 and small focal in 2) within 1 to 16 days after the thrombolytic infuson. Therefore, short-term local thrombolytic infusion fails to prevent myocardial infarction in patients with unstable angina

  14. Temperature-Driven Change in the Unstable Growth Mode on Patterned GaAs(001)

    Tadayyon-Eslami, T.; Phaneuf, R. J.; Kan, H.-C.; Calhoun, L. C.

    2006-01-01

    We observe a dramatic change in the unstable growth mode during GaAs molecular beam epitaxy on patterned GaAs(001) as the temperature is lowered through approximately 540 deg. C, roughly coincident with the preroughening temperature. Observations of the As 2 flux dependence, however, rule out thermodynamic preroughening as driving the growth mode change. Similar observations rule out the change in surface reconstruction as the cause. Instead, we find evidence that the change in the unstable growth mode can be explained by a competition between the decreased adatom collection rate on small terraces and a small anisotropic barrier to adatom diffusion downward across step bunches

  15. Partners in crime: bidirectional transcription in unstable microsatellite disease.

    Batra, Ranjan; Charizanis, Konstantinos; Swanson, Maurice S

    2010-04-15

    Nearly two decades have passed since the discovery that the expansion of microsatellite trinucleotide repeats is responsible for a prominent class of neurological disorders, including Huntington disease and fragile X syndrome. These hereditary diseases are characterized by genetic anticipation or the intergenerational increase in disease severity accompanied by a decrease in age-of-onset. The revelation that the variable expansion of simple sequence repeats accounted for anticipation spawned a number of pathogenesis models and a flurry of studies designed to reveal the molecular events affected by these expansions. This work led to our current understanding that expansions in protein-coding regions result in extended homopolymeric amino acid tracts, often polyglutamine or polyQ, and deleterious protein gain-of-function effects. In contrast, expansions in noncoding regions cause RNA-mediated toxicity. However, the realization that the transcriptome is considerably more complex than previously imagined, as well as the emerging regulatory importance of antisense RNAs, has blurred this distinction. In this review, we summarize evidence for bidirectional transcription of microsatellite disease genes and discuss recent suggestions that some repeat expansions produce variable levels of both toxic RNAs and proteins that influence cell viability, disease penetrance and pathological severity.

  16. Unstable fluid flow in a water-cooled heating channel

    Delayre, R.; Saunier, J.P.

    1961-01-01

    Experimental investigations of the instable behavior of a pressurized water flow in forced convection in a heating channel, with subcooled or bulk boiling have been carried. Tests were conducted at 1140, 850 and 570 psi. The test section was 35 in. high, surmounted by a 25.4 in. riser, these sections were by-passed by a pipe where the flow was between 1 and 4 times the flow in the test section. The water velocity (in the test section) was between 1.6 and 6.6 ft/s. Under certain conditions oscillations with a period of several seconds and perfectly stable have been observed. A mathematical model has been defined and a good agreement obtained for the main characteristics of the oscillations. It seems that the dimensions of the riser have a determining effect: the inception of bulk boiling gives an important variation of the driving head which can generate oscillations due to the non-zero delay for the system to reach its equilibrium. (author) [fr

  17. Biological factors of natural and artificial ecosystems stable (unstable) functioning

    Pechurkin, Nikolai S.

    The problem of sustainable development of humanity on Earth and the problem of supporting human life in space have the same scientific and methodological bases. The key to solve both problems is a long term maintenance of balanced material cycle. As a whole, natural or artificial ecosystems are to be more closed than open, but their elements (links of systems) are to be substantially open in interactions with each other. Prolonged stable interactions of different links have to have unique joint results - closed material cycling or biotic turnover. It is necessary to include, at least, three types of main links into any system to support real material cycling: producers, consumers, reducers. Producer links are now under studies in many laboratories. It is evident that the higher productivity of link, the lower link stability. Especially, it concerns with parasite impact to plants. As usual, artificial ecosystems are more simple (incomplete) than natural ecosystems, sometimes, they have not enough links for prolonged stable functioning. For example, life support system for space flight can be incomplete in consumer link, having only some crew persons, instead of interacting populations of consumers. As for reducer link, it is necessary to "organize" a special coordinated work of microbial biocenoses to fulfill proper cycling. Possible evolution of links, their self development is a matter of special attention for the maintenance of prolonged stable functioning. It's the most danger for systems with populations of quickly reproducing, so-called, R - strategists, according to symbols of logistic equation. From another side, quick reproduction of R - strategists is able to increase artificial ecosystems and their links functioning. After some damages of system, R - strategist's link can be quickly "self repaired" up to level of normal functioning. Some experimental data of this kind and mathematical models are to be discussed in the paper. This work is supported by

  18. Unstable relationship between the Arctic Oscillation and East Asian jet stream in winter and possible mechanisms

    Liu, Yang; He, Shengping; Li, Fei; Wang, Huijun; Zhu, Yali

    2017-12-01

    Based on long-term reanalysis datasets, this study revealed that the relationship between the Arctic Oscillation (AO) and the East Asian jet stream (EAJS) is significant negative during 1925-1945 and 1985-2005 (significant periods; hereafter SPs) whereas insignificant during 1900-1920 and 1955-1975 (insignificant periods; ISPs). The unstable AO-EAJS relationship might be related to the interdecadal change of AO's spatial structure. During SPs winters, anomalous positive AO events are characterized by atmospheric negative anomalies in the Arctic with two anomalous positive centers located in the extratropical Atlantic and Pacific, exhibiting a quasi-barotropic structure. By contrast, the anomalous center in the North Pacific is barely observed during ISPs winters. Further analysis indicated that such interdecadal change might be attributed to change of troposphere-stratosphere coupling and the North Pacific air-sea interaction. On the one hand, anomalous AO at surface is closely related to obvious planetary waves downward from the stratosphere during SPs, which favors the subtropics-Arctic teleconnection. On the other hand, the Interdecadal Pacific Oscillation (IPO) shows warm phase during SPs, which induces larger variance of the Aleutian Low and more intensive divergence anomalies at upper level troposphere. Due to the advection of vorticity induced by stronger divergence is favorable for stronger Rossby wave source, the Rossby wave activity is much stronger and could further propagate eastward to the North Atlantic during SPs, resulting in the Pacific-Atlantic teleconnection. Such a mechanism is supported by the numerical simulations from two individual models that are perturbed by warm/cold IPO sea surface temperature anomalies.

  19. Study on Physics of Unstable Nuclei within the Framework of Vietnam-France Joint Laboratory

    Le Xuan Chung; Dao Tien Khoa; Nguyen Tuan Khai; Do Cong Cuong; Tran Huu Phat; Bui Minh Loc; Tran Viet Nhan Hao

    2015-01-01

    The study on nuclear physics is presented by both theory and experiment. For theory, we present the analyses on the scatterings of nucleon (proton and neutron) and nucleus. This approach is known as the simplest way to study nuclei of interest because nucleon is screen-tested. Precise nuclear radii of "6","8He has been obtained from the Glauber analysis on the experimental data. The microscopic calculations of elastic nucleon-nucleus scattering off double-closed shell nuclei "1"6O and "2"0"8Pb at energies below 50 MeV were performed. This work will be a key input for the prediction of elastic and inelastic scattering reactions of nuclei far from the stability valley. Through analysis on the charge-exchange ("3He,t) reaction, the neutron skins of "2"0"8Pb and "9"0Zr have been obtained which were in a good agreement with previous works. Further study on elastic α+α scattering at low energy gives possible explanation of a long-standing inconsistency of the double-folding model in its study on this system and α-nucleus scattering using the same realistic density dependent M3Y interaction. For the experiment, the experiments performed at RIKEN and IPN Orsay are reported. The results from the RIKEN experiments shows that the 2"+ and 4"+ energies of "6"6Cr and "7"0","7"2Fe were measured for the first time. The preliminary results on the data of "6"8Fe show 4 de-excited gammas on the spectrum of this isotope. The level scheme of "6"8Fe is built. The results from the IPN Orsay experimental data analysis improved level schemes of the neutron-rich "8"3","8"4Ge and "8"2As isotopes. The experimental data of unstable nuclei is significant in nuclear structure or shell evolution study. (author)

  20. W-pair production near threshold in unstable particle effective theory

    Falgari, Pietro

    2008-11-07

    In this thesis we present a dedicated study of the four-fermion production process e{sup +}e{sup -}{yields}{mu}{sup -} anti {nu}{sub {mu}}u anti dX near the W-pair production threshold, in view of its importance for a precise determination of the W-boson mass at the ILC. The calculation is performed in the framework of unstable-particle effective theory, which allows for a gauge-invariant inclusion of instability effects, and for a systematic approximation of the full cross section with an expansion in the coupling constants, the ratio {gamma}{sub W}/M{sub W}, and the non-relativistic velocity v of the W boson. The effective-theory result, computed to next-to-leading order in the expansion parameters {gamma}{sub W}/M{sub W}{proportional_to}{alpha}{sub ew}{proportional_to}v{sup 2}, is compared to the full numerical next-to-leading order calculation of the four-fermion production cross section, and agreement to better than 0.5% is found in the region of validity of the effective theory. Furthermore, we estimate the contributions of missing higher-order corrections to the four-fermion process, and how they translate into an error on the W-boson mass determination. We find that the dominant theoretical uncertainty on MW is currently due to an incomplete treatment of initial-state radiation, while the remaining combined uncertainty of the two NLO calculations translates into {delta}M{sub W}{approx} 5 MeV. The latter error is removed by an explicit computation of the dominant missing terms, which originate from the expansion in v of next-to-next-to-leading order Standard Model diagrams. The effect of resummation of logarithmically-enhanced terms is also investigated, but found to be negligible. (orig.)

  1. Polarization leakage in epoch of reionization windows - II. Primary beam model and direction-dependent calibration

    Asad, K. M. B.; Koopmans, L. V. E.; Jelić, V.; Ghosh, A.; Abdalla, F. B.; Brentjens, M. A.; de Bruyn, A. G.; Ciardi, B.; Gehlot, B. K.; Iliev, I. T.; Mevius, M.; Pandey, V. N.; Yatawatta, S.; Zaroubi, S.

    2016-11-01

    Leakage of diffuse polarized emission into Stokes I caused by the polarized primary beam of the instrument might mimic the spectral structure of the 21-cm signal coming from the epoch of reionization (EoR) making their separation difficult. Therefore, understanding polarimetric performance of the antenna is crucial for a successful detection of the EoR signal. Here, we have calculated the accuracy of the nominal model beam of Low Frequency ARray (LOFAR) in predicting the leakage from Stokes I to Q, U by comparing them with the corresponding leakage of compact sources actually observed in the 3C 295 field. We have found that the model beam has errors of ≤10 per cent on the predicted levels of leakage of ˜1 per cent within the field of view, I.e. if the leakage is taken out perfectly using this model the leakage will reduce to 10-3 of the Stokes I flux. If similar levels of accuracy can be obtained in removing leakage from Stokes Q, U to I, we can say, based on the results of our previous paper, that the removal of this leakage using this beam model would ensure that the leakage is well below the expected EoR signal in almost the whole instrumental k-space of the cylindrical power spectrum. We have also shown here that direction-dependent calibration can remove instrumentally polarized compact sources, given an unpolarized sky model, very close to the local noise level.

  2. Theoretical estimation of absorbed dose to organs in radioimmunotherapy using radionuclides with multiple unstable daughters

    Hamacher, K.A.; Sgouros, G.

    2001-01-01

    The toxicity and clinical utility of long-lived alpha emitters such as Ac-225 and Ra-223 will depend upon the fate of alpha-particle emitting unstable intermediates generated after decay of the conjugated parent. For example, decay of Ac-225 to a stable element yields four alpha particles and seven radionuclides. Each of these progeny has its own free-state biodistribution and characteristic half-life. Therefore, their inclusion for a more accurate prediction of absorbed dose and potential toxicity requires a formalism that takes these factors into consideration as well. To facilitate the incorporation of such intermediates into the dose calculation, a previously developed methodology (model 1) has been extended. Two new models (models 2 and 3) for allocation of daughter products are introduced and are compared with the previously developed model. Model 1 restricts the transport to a function that yields either the place of origin or the place(s) of biodistribution depending on the half-life of the parent radionuclide. Model 2 includes the transient time within the bloodstream and model 3 incorporates additional binding at or within the tumor. This means that model 2 also allows for radionuclide decay and further daughter production while moving from one location to the next and that model 3 relaxes the constraint that the residence time within the tumor is solely based on the half-life of the parent. The models are used to estimate normal organ absorbed doses for the following parent radionuclides: Ac-225, Pb-212, At-211, Ra-223, and Bi-213. Model simulations are for a 0.1 g rapidly accessible tumor and a 10 g solid tumor. Additionally, the effects of varying radiolabled carrier molecule purity and amount of carrier molecules, as well as tumor cell antigen saturation are examined. The results indicate that there is a distinct advantage in using parent radionuclides such as Ac-225 or Ra-223, each having a half-life of more than 10 days and yielding four alpha

  3. Computed tomography fluoroscopy-guided placement of iliosacral screws in patients with unstable posterior pelvic fractures

    Iguchi, Toshihiro; Ogawa, Ken-Ichi; Doi, Takeshi; Munetomo, Kazuo; Miyasho, Koji; Hiraki, Takao; Kanazawa, Susumu; Ozaki, Toshifumi

    2010-01-01

    The purpose of this study was to evaluate retrospectively the safety and effectiveness of the computed tomography (CT) fluoroscopy-guided placement of iliosacral screws in patients with unstable posterior pelvic fractures. Six patients (four women and two men; mean age 55.8 years; range 35-77 years) with unstable posterior pelvic fractures underwent iliosacral screw placement under CT fluoroscopy guidance between November 2007 and August 2008. Unstable pelvic ring injury (AO types B and C) was the indication for this procedure. In all the six patients except one, CT fluoroscopy-guided placement had been technically successful. In one patient, a second screw had been inserted, with a tilt to the caudal site, and slightly advanced into the extrasacral body; afterward, it could be exchanged safely for a shorter screw. Five patients and one patient underwent placement of two screws and one screw, respectively. The mean duration of the procedure was 15.0 min (range 9-30 min) per screw; the duration was 12.3 min and 18.2 min for the first and second screws, respectively. No complications requiring treatment occurred during or after the procedure. The mean clinical and radiologic follow-up period was 14 months (range 6-21 months). All pelvic injuries had healed satisfactorily, without complication, and all patients are now doing well clinically and can walk. CT fluoroscopy-guided placement of iliosacral screws is a safe and effective treatment in patients with unstable posterior pelvic fractures. (orig.)

  4. Treatment of unstable trochanteric fractures : the balance between man and material

    I.B. Schipper (Inger)

    2003-01-01

    textabstractTreatment of unstable trochanteric fractures poses a challenge to surgeons in many ways. Accepting this challenge requires understanding of those parameters that determine the outcome. In operative fracture care at least four elements influence the outcome of treatment: the patient, the

  5. Treatment of Unstable Trochanteric Femur Fractures: Proximal Femur Nail Versus Proximal Femur Locking Compression Plate.

    Singh, Ashutosh Kumar; Narsaria, Nidi; G R, Arun; Srivastava, Vivek

    Unstable trochanteric femur fractures are common fractures that are difficult to manage. We conducted a prospective study to compare functional outcomes and complications of 2 different implant designs, proximal femur nail (PFN) and proximal femur locking compression plate (PFLCP), used in internal fixation of unstable trochanteric femur fractures. On hospital admission, 48 patients with unstable trochanteric fractures were randomly assigned (using a sealed envelope method) to treatment with either PFN (24 patients) or PFLCP (24 patients). Perioperative data and complications were recorded. All cases were followed up for 2 years. The groups did not differ significantly (P > .05) in operative time, reduction quality, complications, hospital length of stay, union rate, or time to union. Compared with the PFLCP group, the PFN group had shorter incisions and less blood loss. Regarding functional outcomes, there was no significant difference in mean Harris Hip Score (P = .48) or Palmer and Parker mobility score (P = .58). Both PFN and PFLCP are effective in internal fixation of unstable trochanteric femur fractures.

  6. Treatment of unstable trochanteric fractures. Randomised comparison of the gamma nail and the proximal femoral nail.

    Schipper, I.B.; Steyerberg, E.W.; Castelein, R.M.; Heijden, F.H. van der; Hoed, P.T. den; Kerver, A.J.; Vugt, A.B. van

    2004-01-01

    The proximal femoral nail (PFN) is a recently introduced intramedullary system, designed to improve treatment of unstable trochanteric fractures of the hip. In a multicentre prospective clinical study, the intra-operative use, complications and outcome of treatment using the PFN (n = 211) were

  7. Risk stratification by using non-invasive radionuclide imaging in patients with unstable angina spec tories

    Saghari, M.

    2002-01-01

    Unstable angina represents a heterogeneous spectrum of clinical entities between chronic stable angina and acute myocardial infraction. Acute ischemic syndromes (including unstable angina) result from abrupt reduction in coronary flow, frequently after atherosclerotic plaque disruption and with or without associated thrombosis or vasospasm. Nuclear cardiology studies and in particular, myocardial perfusion imaging are powerful noninvasive tools for detecting and assessing the severity of acute ischemic syndromes, including unstable angina pec tories. The information derived from a nuclear cardiology study can answer unresolved clinical question and aid in subsequent patient management, specifically jeopardized myocardium detected during spontaneously occurring acute chest pain or controlled stress testing are important determinant of: 1) The need for admission to an intensive care monitoring unit 2) The need for and urgency of coronary angiography 3) The appropriate use of percutaneous or surgical coronary revascularization procedures. Extensive information suggests the stress nuclear perfusion imaging is the best validated technique for predischarge risk stratification with unstable angina patients who have been medically stabilized. Early information suggests avoidance of unecessary coronary angiography or revascularization is the cost effective strategy

  8. Robustness of unstable attractors in arbitrarily sized pulse-coupled networks with delay

    Broer, Hendrik; Efstathiou, Konstantinos; Subramanian, Easwar

    We consider arbitrarily large networks of pulse-coupled oscillators with non-zero delay where the coupling is given by the Mirollo-Strogatz function. We prove that such systems have unstable attractors (saddle periodic orbits whose stable set has non-empty interior) in an open parameter region for

  9. A study of unstable slopes in permafrost areas : Alaskan case studies used as a training tool.

    2011-12-01

    This report is the companion to the PowerPoint presentation for the project A Study of Unstable Slopes in Permafrost: Alaskan Case Studies Used as a Training Tool. The objectives of this study are 1) to provide a comprehensive review of literat...

  10. Experimental Demonstration of the Fermi-Pasta-Ulam Recurrence in a Modulationally Unstable Optical Wave

    Van Simaeys, G.; Emplit, Ph.; Haelterman, M.

    2001-01-01

    Through a detailed spectral analysis of the propagation of square-shaped laser pulses in optical fibers, we provide the experimental demonstration of the Fermi-Pasta-Ulam recurrence phenomenon in modulationally unstable optical waves ruled by the nonlinear Schroedinger equation

  11. Complex and unstable simple elbow dislocations: a review and quantitative analysis of individual patient data

    de Haan, Jeroen; Schep, Niels; Tuinebreijer, Wim; den Hartog, Dennis

    2010-01-01

    The primary objective of this review of the literature with quantitative analysis of individual patient data was to identify the results of available treatments for complex elbow dislocations and unstable simple elbow dislocations. The secondary objective was to compare the results of patients with

  12. Ankle proprioception is not targeted by exercises on an unstable surface

    Kiers, H.; Brumagne, S.; van Dieen, J.; Wees, P.J. van der; Vanhees, L.

    2012-01-01

    Laboratory study using a repeated measures design. The aim of this study was to determine if ankle proprioception is targeted in exercises on unstable surfaces. Lateral ankle sprain (LAS) has recurrence rates over 70%, which are believed to be due to a reduced accuracy of proprioceptive signals from

  13. Serum potassium values in relation to the use of diuretics in patients with unstable angina pectoris

    van Gilst, W. H.; Tijssen, J. G.; van Es, G. A.; Lubsen, J.

    1988-01-01

    Transient hypokalaemia may occur in acutely ill patients and is associated with an increased incidence of life-threatening arrhythmias. Therefore, we performed a retrospective analysis of the serum potassium values of 538 patients with unstable angina included in the Holland Interuniversity

  14. Research of Medical Expenditure among Inpatients with Unstable Angina Pectoris in a Single Center

    Suo-Wei Wu

    2017-01-01

    Conclusions: The classification of DRGs by adopting the type of surgery as the main branch node to develop cost control standards in inpatient treatment of unstable angina pectoris is conducive in standardizing the diagnosis and treatment behaviors of the hospital and reducing economic burdens among patients.

  15. Results of operative fixation of unstable ankle fractures in geriatric patients.

    Pagliaro, A J; Michelson, J D; Mizel, M S

    2001-05-01

    It is widely accepted that operative fixation of unstable ankle fractures yields predictably good outcomes in the general population. The current literature, however reports less acceptable results in the geriatric population age 65 years and older. The current study analyzes the outcome of the surgical treatment of unstable ankle fractures in patients at least 65 years old. Twenty three patient over 65 years old were surgically treated after sustaining 21 (91%) closed and 2 (9%) open grade II unstable ankle fractures. Fractures were classified according to the Danis-Weber and Lauge-Hansen schemes. Fracture type was predominantly Weber B (21/23, 91%), or supination external rotation stage IV (21/23, 91%). Fracture union rate was 100%. There were three significant complications including a lateral wound dehiscence with delayed fibular union in an open fracture dislocation, and two below knee amputations, neither of which was directly related to the fracture treatment. There were three minor complications; one superficial wound infection and two cases of prolonged incision drainage, all of which resolved without further surgical intervention. Complications were associated with open fractures and preexisting systemic disease. These results indicate that open reduction and internal fixation of unstable ankle fractures in geriatric patients is an efficacious treatment regime that with results that are comparable to the general population.

  16. Buoyant Unstable Behavior of Initially Spherical Lean Hydrogen-Air Premixed Flames

    Zuo-Yu Sun

    2014-07-01

    Full Text Available Buoyant unstable behavior in initially spherical lean hydrogen-air premixed flames within a center-ignited combustion vessel have been studied experimentally under a wide range of pressures (including reduced, normal, and elevated pressures. The experimental observations show that the flame front of lean hydrogen-air premixed flames will not give rise to the phenomenon of cellular instability when the equivalence ratio has been reduced to a certain value, which is totally different from the traditional understanding of the instability characteristics of lean hydrogen premixed flames. Accompanied by the smoothened flame front, the propagation mode of lean hydrogen premixed flames transitions from initially spherical outwardly towards upwardly when the flames expand to certain sizes. To quantitatively investigate such buoyant instability behaviors, two parameters, “float rate (ψ” and “critical flame radius (Rcr”, have been proposed in the present article. The quantitative results demonstrate that the influences of initial pressure (Pint on buoyant unstable behaviors are different. Based on the effects of variation of density difference and stretch rate on the flame front, the mechanism of such buoyant unstable behaviors has been explained by the competition between the stretch force and the results of gravity and buoyancy, and lean hydrogen premixed flames will display buoyant unstable behavior when the stretch effects on the flame front are weaker than the effects of gravity and buoyancy.

  17. The role of imaging in the choice of correct treatment of unstable thoraco-lumbar fractures

    Valentini, Maria Consuelo; Busch, Rolf; Ferraris, Maria Maddalena; Venturi, Fabrizio

    2006-01-01

    The concept of unstable burst fracture has been discussed since over 50 years and this injury has received much attention in the literature as regards its radiological diagnosis and clinical treatment. The purpose of this article is to review the way we use imaging to diagnose the injury and to guide treatment

  18. Brownian motion surviving in the unstable cubic potential and the role of Maxwell's demon

    Ornigotti, Luca; Ryabov, Artem; Holubec, Viktor; Filip, Radim

    2018-03-01

    The trajectories of an overdamped particle in a highly unstable potential diverge so rapidly, that the variance of position grows much faster than its mean. A description of the dynamics by moments is therefore not informative. Instead, we propose and analyze local directly measurable characteristics, which overcome this limitation. We discuss the most probable particle position (position of the maximum of the probability density) and the local uncertainty in an unstable cubic potential, V (x ) ˜x3 , both in the transient regime and in the long-time limit. The maximum shifts against the acting force as a function of time and temperature. Simultaneously, the local uncertainty does not increase faster than the observable shift. In the long-time limit, the probability density naturally attains a quasistationary form. We interpret this process as a stabilization via the measurement-feedback mechanism, the Maxwell demon, which works as an entropy pump. The rules for measurement and feedback naturally arise from the basic properties of the unstable dynamics. All reported effects are inherent in any unstable system. Their detailed understanding will stimulate the development of stochastic engines and amplifiers and, later, their quantum counterparts.

  19. Randomised, double-blind trial of intravenous diltiazem versus glyceryl trinitrate for unstable angina pectoris

    Gobel, EJAM; Hautvast, RWM; vanGilst, WH; Spanjaard, JN; Hillege, HL; DeJongste, MJL; Molhoek, GP; Lie, KI

    1995-01-01

    The effect of dihydropyridines in patients with unstable angina is discouraging. To find out the effect of the non- dihydropyridine-like calcium-channel blocker diltiazem, a randomised, double-blind trial was conducted comparing diltiazem with glyceryl trinitrate. both given intravenously, in 129

  20. Computer Cataloging of Electronic Journals in Unstable Aggregator Databases: The Hong Kong Baptist University Library Experience.

    Li, Yiu-On; Leung, Shirley W.

    2001-01-01

    Discussion of aggregator databases focuses on a project at the Hong Kong Baptist University library to integrate full-text electronic journal titles from three unstable aggregator databases into its online public access catalog (OPAC). Explains the development of the electronic journal computer program (EJCOP) to generate MARC records for…

  1. Magnetic resonance imaging in patients with unstable angina: comparison with acute myocardial infarction and normals

    Ahmad, M.; Johnson, R.F. Jr.; Fawcett, H.D.; Schreiber, M.H.

    1988-01-01

    The role of magnetic resonance imaging in characterizing normal, ischemic and infarcted segments of myocardium was examined in 8 patients with unstable angina, 11 patients with acute myocardial infarction, and 7 patients with stable angina. Eleven normal volunteers were imaged for comparison. Myocardial segments in short axis magnetic resonance images were classified as normal or abnormal on the basis of perfusion changes observed in thallium-201 images in 22 patients and according to the electrocariographic localization of infarction in 4 patients. T2 relaxation time was measured in 57 myocardial segments with abnormal perfusion (24 with reversible and 33 with irreversible perfusion changes) and in 25 normally perfused segments. T2 measurements in normally perfused segments of patients with acute myocardial infarction, unstable angina and stable angina were within normal range derived from T2 measurements in 48 myocardial segments of 11 normal volunteers (42 +/- 10 ms). T2 in abnormal myocardial segments of patients with stable angina also was not significantly different from normal. T2 of abnormal segments in patients with unstable angina (64 +/- 14 in reversibly ischemic and 67 +/- 21 in the irreversibly ischemic segments) was prolonged when compared to normal (p less than 0.0001) and was not significantly different from T2 in abnormal segments of patients with acute myocardial infarction (62 +/- 18 for reversibly and 66 +/- 11 for irreversibly ischemic segments). The data indicate that T2 prolongation is not specific for acute myocardial infarction and may be observed in abnormally perfused segments of patients with unstable angina

  2. Development of atomic-beam resonance method to measure the nuclear moments of unstable nuclei

    Sugimoto, T., E-mail: sugimoto@ribf.riken.jp [SPring-8 (Japan); Asahi, K. [Tokyo Institute of Technology, Department of Physics (Japan); Kawamura, H.; Murata, J. [Rikkyo University, Department of Physics (Japan); Nagae, D.; Shimada, K. [Tokyo Institute of Technology, Department of Physics (Japan); Ueno, H.; Yoshimi, A. [RIKEN Nishina Center (Japan)

    2008-01-15

    We have been working on the development of a new technique of atomic-beam resonance method to measure the nuclear moments of unstable nuclei. In the present study, an ion-guiding system to be used as an atomic-beam source have been developed.

  3. Background Complex angiographic lesions and clinic presentation in unstable angina. A prospective study

    LLuberas, R.; Mallo, D.; Pouso, J.; Artucio, C.; Korytnicki; Argon, L.; Besada, E.; Tavella, N.

    2002-01-01

    Background Complex angiography lesions and intracoronary thrombus have been identified in unstable angina.Braunwalds categorization has been accepted in the last years.Identifying severe clinical classes class III (angina at rest during the last 48 hours), class C (angina postinfarction) and class c (angina with maximum therapeutic). The main objective of this study was to determine independent associations of Braunwalds classes III, C and c: complex lesions, intracoronary thrombus, total occlusion and distal flux TIMI<3 of the responsible vessel. The secondary objectives were to analyze the angiographic features of the lesion and the responsible vessel. Aprospective study of 300 patients with diagnosed unstable angina, clustered according to Braunwalds clinis classification was done. The angiographic evaluation was performed identifying the responsible lesion and the presence of the complex lesion, intracoronary thrombus, total occlusion and distal flux TIMI<3 of the responsible vessel. A univariate analysis and a multivariate model of binary logistic regression were used. In the 300 patient population, 22 patients with normal coronaries(7.3%) were identified. The responsible lesion was identified in 243 out of the remaining 278 patients (87,4%). Class III was significantly associated with the complex lesion (OR=2.74, IC95%=1,27-5,9) and intracoronary thrombus (OR=2,82 IC95=1,2-6,6). Class C was significantly associated with intracoronary thrombus (OR=3.9),IC95%=1.53-10,0).Class III was and independent predictor for the presence of the complex lesion(OR=1.98, IC 95%=1,01-3,87) and intracoronary thrombus (OR=2,47 IC95%=1,14-5,37). Class C was and independent predictor for the complex lesion (OR=5,05,IC95%=2.25-11,3), infracoronary thrombus (OR=8,04, IC 95%=3,49-18,0), total occlusion (OR=6,49, IC95%=2,67-15,7) and distal flux TIMI<3(OR=3,96,IC 95%=1,87-8,4) There was no significant association between classes III, C and c and the responsible vessel, localization of

  4. Rock slope instabilities in Norway: First systematic hazard and risk classification of 22 unstable rock slopes

    Böhme, Martina; Hermanns, Reginald L.; Oppikofer, Thierry; Penna, Ivanna

    2016-04-01

    Unstable rock slopes that can cause large failures of the rock-avalanche type have been mapped in Norway for almost two decades. Four sites have earlier been characterized as high-risk objects based on expertise of few researchers. This resulted in installing continuous monitoring systems and set-up of an early-warning system for those four sites. Other unstable rock slopes have not been ranked related to their hazard or risk. There are ca. 300 other sites known of which 70 sites were installed for periodic deformation measurements using multiple techniques (Global Navigation Satellite Systems, extensometers, measurement bolts, and others). In 2012 a systematic hazard and risk classification system for unstable rock slopes was established in Norway and the mapping approach adapted to that in 2013. Now, the first 22 sites were classified for hazard, consequences and risk using this classification system. The selection of the first group of sites to be classified was based on an assumed high hazard or risk and importance given to the sites by Norwegian media and the public. Nine of the classified 22 unstable rock slopes are large sites that deform inhomogeneously or are strongly broken up in individual blocks. This suggests that different failure scenarios are possible that need to be analyzed individually. A total of 35 failure scenarios for those nine unstable rock slopes were considered. The hazard analyses were based on 9 geological parameters defined in the classification system. The classification system will be presented based on the Gamanjunni unstable rock slope. This slope has a well developed back scarp that exposes 150 m preceding displacement. The lateral limits of the unstable slope are clearly visible in the morphology and InSAR displacement data. There have been no single structures observed that allow sliding kinematically. The lower extend of the displacing rock mass is clearly defined in InSAR data and by a zone of higher rock fall activity. Yearly

  5. An Improved Statistical Point-source Foreground Model for the Epoch of Reionization

    Murray, S. G.; Trott, C. M.; Jordan, C. H. [ARC Centre of Excellence for All-sky Astrophysics (CAASTRO) (Australia)

    2017-08-10

    We present a sophisticated statistical point-source foreground model for low-frequency radio Epoch of Reionization (EoR) experiments using the 21 cm neutral hydrogen emission line. Motivated by our understanding of the low-frequency radio sky, we enhance the realism of two model components compared with existing models: the source count distributions as a function of flux density and spatial position (source clustering), extending current formalisms for the foreground covariance of 2D power-spectral modes in 21 cm EoR experiments. The former we generalize to an arbitrarily broken power law, and the latter to an arbitrary isotropically correlated field. This paper presents expressions for the modified covariance under these extensions, and shows that for a more realistic source spatial distribution, extra covariance arises in the EoR window that was previously unaccounted for. Failure to include this contribution can yield bias in the final power-spectrum and under-estimate uncertainties, potentially leading to a false detection of signal. The extent of this effect is uncertain, owing to ignorance of physical model parameters, but we show that it is dependent on the relative abundance of faint sources, to the effect that our extension will become more important for future deep surveys. Finally, we show that under some parameter choices, ignoring source clustering can lead to false detections on large scales, due to both the induced bias and an artificial reduction in the estimated measurement uncertainty.

  6. An Improved Statistical Point-source Foreground Model for the Epoch of Reionization

    Murray, S. G.; Trott, C. M.; Jordan, C. H.

    2017-08-01

    We present a sophisticated statistical point-source foreground model for low-frequency radio Epoch of Reionization (EoR) experiments using the 21 cm neutral hydrogen emission line. Motivated by our understanding of the low-frequency radio sky, we enhance the realism of two model components compared with existing models: the source count distributions as a function of flux density and spatial position (source clustering), extending current formalisms for the foreground covariance of 2D power-spectral modes in 21 cm EoR experiments. The former we generalize to an arbitrarily broken power law, and the latter to an arbitrary isotropically correlated field. This paper presents expressions for the modified covariance under these extensions, and shows that for a more realistic source spatial distribution, extra covariance arises in the EoR window that was previously unaccounted for. Failure to include this contribution can yield bias in the final power-spectrum and under-estimate uncertainties, potentially leading to a false detection of signal. The extent of this effect is uncertain, owing to ignorance of physical model parameters, but we show that it is dependent on the relative abundance of faint sources, to the effect that our extension will become more important for future deep surveys. Finally, we show that under some parameter choices, ignoring source clustering can lead to false detections on large scales, due to both the induced bias and an artificial reduction in the estimated measurement uncertainty.

  7. Artificial Neural Network Model to Estimate the Viscosity of Polymer Solutions for Enhanced Oil Recovery

    Pan-Sang Kang

    2016-06-01

    Full Text Available Polymer flooding is now considered a technically- and commercially-proven method for enhanced oil recovery (EOR. The viscosity of the injected polymer solution is the key property for successful polymer flooding. Given that the viscosity of a polymer solution has a non-linear relationship with various influential parameters (molecular weight, degree of hydrolysis, polymer concentration, cation concentration of polymer solution, shear rate, temperature and that measurement of viscosity based on these parameters is a time-consuming process, the range of solution samples and the measurement conditions need to be limited and precise. Viscosity estimation of the polymer solution is effective for these purposes. An artificial neural network (ANN was applied to the viscosity estimation of FlopaamTM 3330S, FlopaamTM 3630S and AN-125 solutions, three commonly-used EOR polymers. The viscosities measured and estimated by ANN and the Carreau model using Lee’s correlation, the only method for estimating the viscosity of an EOR polymer solution in unmeasured conditions, were compared. Estimation accuracy was evaluated by the average absolute relative deviation, which has been widely used for accuracy evaluation of the results of ANN models. In all conditions, the accuracy of the ANN model is higher than that of the Carreau model using Lee’s correlation.

  8. Unstable angina

    ... pressure High LDL cholesterol Low HDL cholesterol Male gender Sedentary lifestyle (not getting enough exercise) Obesity Older ... or it is not steady You are having trouble taking your heart medicines You have any other ...

  9. Unstable Angina

    ... for Heart.org CPR & ECC for Heart.org Shop for Heart.org Causes for Heart.org Advocate ... resting. The most common cause is reduced blood flow to the heart muscle because the coronary arteries ...

  10. A computer aided measurement method for unstable pelvic fractures based on standardized radiographs

    Zhao, Jing-xin; Zhao, Zhe; Zhang, Li-cheng; Su, Xiu-yun; Du, Hai-long; Zhang, Li-ning; Zhang, Li-hai; Tang, Pei-fu

    2015-01-01

    To set up a method for measuring radiographic displacement of unstable pelvic ring fractures based on standardized X-ray images and then test its reliability and validity using a software-based measurement technique. Twenty-five patients that were diagnosed as AO/OTA type B or C pelvic fractures with unilateral pelvis fractured and dislocated were eligible for inclusion by a review of medical records in our clinical centre. Based on the input pelvic preoperative CT data, the standardized X-ray images, including inlet, outlet, and anterior-posterior (AP) radiographs, were simulated using Armira software (Visage Imaging GmbH, Berlin, Germany). After representative anatomic landmarks were marked on the standardized X-ray images, the 2-dimensional (2D) coordinates of these points could be revealed in Digimizer software (Model: Mitutoyo Corp., Tokyo, Japan). Subsequently, we developed a formula that indicated the translational and rotational displacement patterns of the injured hemipelvis. Five separate observers calculated the displacement outcomes using the established formula and determined the rotational patterns using a 3D-CT model based on their overall impression. We performed 3D reconstruction of all the fractured pelvises using Mimics (Materialise, Haasrode, Belgium) and determined the translational and rotational displacement using 3-matic suite. The interobserver reliability of the new method was assessed by comparing the continuous measure and categorical outcomes using intraclass correlation coefficient (ICC) and kappa statistic, respectively. The interobserver reliability of the new method for translational and rotational measurement was high, with both ICCs above 0.9. Rotational outcome assessed by the new method was the same as that concluded by 3-matic software. The agreement for rotational outcome among orthopaedic surgeons based on overall impression was poor (kappa statistic, 0.250 to 0.426). Compared with the 3D reconstruction outcome, the

  11. Influence of unstable footwear on lower leg muscle activity, volume change and subjective discomfort during prolonged standing.

    Karimi, Zanyar; Allahyari, Teimour; Azghani, Mahmood Reza; Khalkhali, Hamidreza

    2016-03-01

    The present study was an attempt to investigate the effect of unstable footwear on lower leg muscle activity, volume change and subjective discomfort during prolonged standing. Ten healthy subjects were recruited to stand for 2 h in three footwear conditions: barefoot, flat-bottomed shoe and unstable shoe. During standing, lower leg discomfort and EMG activity of medial gastrocnemius (MG) and tibialis anterior (TA) muscles were continuously monitored. Changes in lower leg volume over standing time also were measured. Lower leg discomfort rating reduced significantly while subjects standing on unstable shoe compared to the flat-bottomed shoe and barefoot condition. For lower leg volume, less changes also were observed with unstable shoe. The activity level and variation of right MG muscle was greater with unstable shoe compared to the other footwear conditions; however regarding the left MG muscle, significant difference was found between unstable shoe and flat-bottomed shoe only for activity level. Furthermore no significant differences were observed for the activity level and variation of TA muscles (right/left) among all footwear conditions. The findings suggested that prolonged standing with unstable footwear produces changes in lower leg muscles activity and leads to less volume changes. Perceived discomfort also was lower for this type of footwear and this might mean that unstable footwear can be used as ergonomic solution for employees whose work requires prolonged standing. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  12. Minimal gain marching schemes: searching for unstable steady-states with unsteady solvers

    de S. Teixeira, Renan; S. de B. Alves, Leonardo

    2017-12-01

    Reference solutions are important in several applications. They are used as base states in linear stability analyses as well as initial conditions and reference states for sponge zones in numerical simulations, just to name a few examples. Their accuracy is also paramount in both fields, leading to more reliable analyses and efficient simulations, respectively. Hence, steady-states usually make the best reference solutions. Unfortunately, standard marching schemes utilized for accurate unsteady simulations almost never reach steady-states of unstable flows. Steady governing equations could be solved instead, by employing Newton-type methods often coupled with continuation techniques. However, such iterative approaches do require large computational resources and very good initial guesses to converge. These difficulties motivated the development of a technique known as selective frequency damping (SFD) (Åkervik et al. in Phys Fluids 18(6):068102, 2006). It adds a source term to the unsteady governing equations that filters out the unstable frequencies, allowing a steady-state to be reached. This approach does not require a good initial condition and works well for self-excited flows, where a single nonzero excitation frequency is selected by either absolute or global instability mechanisms. On the other hand, it seems unable to damp stationary disturbances. Furthermore, flows with a broad unstable frequency spectrum might require the use of multiple filters, which delays convergence significantly. Both scenarios appear in convectively, absolutely or globally unstable flows. An alternative approach is proposed in the present paper. It modifies the coefficients of a marching scheme in such a way that makes the absolute value of its linear gain smaller than one within the required unstable frequency spectra, allowing the respective disturbance amplitudes to decay given enough time. These ideas are applied here to implicit multi-step schemes. A few chosen test cases

  13. Fluid mechanical dispersion of airborne pollutants inside urban street canyons subjecting to multi-component ventilation and unstable thermal stratifications.

    Mei, Shuo-Jun; Liu, Cheng-Wei; Liu, Di; Zhao, Fu-Yun; Wang, Han-Qing; Li, Xiao-Hong

    2016-09-15

    The pedestrian level pollutant transport in street canyons with multiple aspect ratios (H/W) is numerically investigated in the present work, regarding of various unstable thermal stratification scenarios and plain surrounding. Non-isothermal turbulent wind flow, temperature field and pollutant spread within and above the street canyons are solved by the realizable k-ε turbulence model along with the enhanced wall treatment. One-vortex flow regime is observed for shallow canyons with H/W=0.5, whereas multi-vortex flow regime is observed for deep canyons with H/W=2.0. Both one-vortex and multi-vortex regimes could be observed for the street canyons with H/W=1.0, where the secondary vortex could be initiated by the flow separation and intensified by unstable thermal stratification. Air exchange rate (AER) and pollutant retention time are adopted to respectively evaluate the street canyon ventilation and pollutant removal performance. A second-order polynomial functional relationship is established between AER and Richardson number (Ri). Similar functional relationship could be established between retention time and Ri, and it is only valid for canyons with one-vortex flow regime. In addition, retention time could be prolonged abruptly for canyons with multi-vortex flow regime. Very weak secondary vortex is presented at the ground level of deep canyons with mild stratification, where pollutants are highly accumulated. However, with the decrease of Ri, pollutant concentration adjacent to the ground reduces accordingly. Present research could be applied to guide the urban design and city planning for enhancing pedestrian environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. On the persistence of unstable bump-on-tail electron velocity distributions in the earth's foreshock

    Klimas, Alexander J.; Fitzenreiter, Richard J.

    1988-01-01

    This paper presents further evidence for the persistence of bump-on-tail unstable reduced velocity distributions in the earth's electron foreshock, which contradicts the understanding of quasi-linear saturation of the bump-on-tail instability. A modified theory for the saturation of the bump-on-tail instability in the earth's foreshock is proposed to explain the mechanism of this persistence, and the predictions are compared to the results of a numerical simulation of the electron plasma in the foreshock. The results support the thesis that quasi-linear saturation of the bump-on-tail instability is modified in the foreshock, due to the driven nature of the region, so that at saturation the stabilized velocity distribution still appears bump-on-tail unstable to linear plasma analysis.

  15. Damping capacity of unstable steels on chromium-nickel-manganese base

    Kochkin, L.I.; Rudakov, A.A.

    1982-01-01

    The paper deals with results of a study on the energy scattering in OKh13N3G8, 20Kh13N3G4 and 30Kh13N3G4 unstable steels. It is shown that the development of microplastic strains most easily occurs in low-carbon steel having a two-phase structure in the initial state. The proceeding of microplastic deformations in carbon unstable steels is limited by the interstitial atom effect on the dislocation movement. It is established that in OKh13N3G8 steel the martensite α→γ- transformation begins under the cyclic stress amplitudes below the yield point of this steel. The steels studied possess a high vibrostrength [ru

  16. Initial and regime situations in the decay of unstable quantum systems

    Rimini, A.; Zambotti, G.

    1980-01-01

    Two different definitions of survival probability in the decay of an unstable quantum system are considered and the equations for them are deduced from the equation for the density operator. The regime situation for the ensemble of unstable systems is studied and the density operator in such a situation is derived. The possible definitions of lifetime are discussed. If the adopted definition makes reference to all time including the early ones, then it is compulsory to specify exactly the state at the initial time. The correct equations for the survival probabilities in such conditions are derived. Two typical examples of decay experiments are considered and the influence of the initial preparation on the mean life is discussed. Numerical examples are given. (author)

  17. Damping capacity of unstable steels on chromium-nickel-manganese base

    Kochkin, L.I.; Rudakov, A.A. (Kirovskij Politekhnicheskij Inst. (USSR))

    1982-02-01

    The paper deals with results of a study on the energy scattering in OKh13N3G8, 20Kh13N3G4 and 30Kh13N3G4 unstable steels. It is shown that the development of microplastic strains most easily occurs in low-carbon steel having a two-phase structure in the initial state. The proceeding of microplastic deformations in carbon unstable steels is limited by the interstitial atom effect on the dislocation movement. It is established that in OKh13N3G8 steel the martensite ..cap alpha --> gamma..- transformation begins under the cyclic stress amplitudes below the yield point of this steel. The steels studied possess a high vibrostrength.

  18. Retrospective dosimetry using Japanese brick quartz: A way forward despite an unstable fast decaying OSL signal

    Fujita, Hiroki; Jain, Mayank; Murray, A.S.

    2011-01-01

    signals has been carried out towards identification of common source traps. It is observed that OSL from Japanese brick quartz shows unusual luminescence characteristics; in particular, the initial fast decaying OSL signal contains a dominant (>90%) thermally unstable component related to the 85 °C TL...... peak, which necessitates a prior heat treatment. A single-aliquot regenerative-dose (SAR) protocol is developed and tested using thermal treatments intended to isolate a stable dosimetric signal. A minimum detection limit of 65 mGy is then estimated using this protocol. Following irradiation using 60Co...... of Japanese brick quartz examined here can be used to derive precise estimates of accident dose, and, possibly to distinguish between sources of gamma radiation in a nuclear accident. To our knowledge, this is the first report on the existence of an unstable fast decaying OSL signal in quartz derived from...

  19. Analysis of unstable secondary particles produced in jet of 30 TeV energy sum

    Ogata, Takeshi

    1978-01-01

    High energy jet shower with energy sum of about 30 TeV has been obtained in the airplane-bone emulsion chamber. The size of the emulsion chamber was 20 cm x 25 cm x 12 cm. The airplane altitude was 260 g/cm 2 , and the exposure time was 600 hours. In this experiment, two jet events were found, and one of two events, KG-7, was the largest obtained so far. Three secondary charged particles produced by high energy interaction were analysed in detail. The analysis indicated that three charged particles seemed to be created by the decay of an unstable secondary particle. The lifetime of the unstable particle was estimated to be 10 -3 - 10 -14 sec, and this particle seems to be a charm particle. (Yoshimori, M.)

  20. On the Fate of Unstable Circumbinary Planets: Tatooine’s Close Encounters with a Death Star

    Sutherland, Adam P.; Fabrycky, Daniel C.

    2016-02-01

    Circumbinary planets whose orbits become unstable may be ejected, accreted, or even captured by one of the stars. We quantify the relative rates of these channels, for a binary of secondary star’s mass fraction 0.1 with an orbit of 1 AU. The most common outcome is ejection, which happens ∼80% of the time. If binary systems form circumbinary planets readily and sloppily, this process may fill the Milky Way with free-floating planets. A significant fraction of the time, ∼20%, the unstable planet strikes the primary or secondary. We tracked whether a Jupiter-like planet would undergo tidal stripping events during close passages, and find that these events are rarely strong enough to capture the planet, although this may be observable via free-floating planets that are heated or spun-up by this process.

  1. Analysis of unstable DNA sequence in FRM1 gene in Polish families with fragile X syndrome

    Milewski, Michal; Bal, Jerzy; Obersztyn, Ewa; Bocian, Ewa; Mazurczak, Tadeusz; Zygulska, Marta; Horst, Juergen; Deelen, Wout H.; Halley, Dicky J.J.

    1996-01-01

    The unstable DNA sequence in the FMR1 gene was analyzed in 85 individuals from Polish families with fragile X syndrome in order to characterize mutations responsible for the disease in Poland. In all affected individuals classified on the basis of clinical features and expression of the fragile site at X(q27.3) a large expansion of the unstable sequence (full mutation) was detected. About 5% (2 of 43) of individuals with full mutation did not express the fragile site. Among normal alleles, ranging in size from 20 to 41 CGC repeats, allele with 29 repeats was the most frequent (37%). Transmission of premutated and fully mutated alleles to the offspring was always associated with size increase. No change in repeat number was found when normal alleles were transmitted. (author). 19 refs., 4 figs, 1 tab

  2. Fixation of Trochanteric Fragments in Cementless Bipolar Hemiarthroplasty of Unstable Intertrochanteric Fracture: Cerclage Wiring.

    Lee, Young-Kyun; Park, Chan Ho; Koo, Kyung-Hoi

    2017-12-01

    Bipolar hemiarthroplasty (HA) is an option for the treatment of unstable intertrochanteric fracture in elderly patients. There is a raising concern regarding cable-grip related complications for the fixation of trochanteric fragments. Therefore, the aim of this study was to evaluate outcome of cementless HA with fixation for the trochanteric fragments using monofilament wires in unstable intertrochanteric fracture. We reviewed 92 cementless bipolar HAs using a grit-blasted long stem design for unstable intertrochanteric fractures in 91 elderly patients with a mean age of 81.7 years. During the arthroplasty, trochanteric fracture fragments were fixed using 1 or 2 vertical wires and transverse wires. We evaluated the clinical outcomes such as abductor power, ambulatory ability and wire-related complications, and radiologic outcomes including the union of the trochanteric fragment and subsidence of stem. Sixty-two patients were followed for a minimum of 2 years (mean, 59 months) postoperatively. The mean abductor power and Koval category was 4.1 (range, 3 to 5) and 4.6 (range, 1 to 6). The wire was broken in 3 hips (4.8%) and the nonunion of the greater trochanter occurred in 1 hips (1.6%). Two stems subsided by 3 mm and 8 mm, respectively, during postoperative 6 weeks, after which the subsidence was not progressive. Cerclage wiring of the trochanter using monofilament wire leads to acceptable outcome in cementless HA for senile patients with unstable intertrochanteric fracture. Cerclage wiring using a monofilament wire is recommended for the fixation of trochanteric fragments.

  3. Closed reduction with CT-guided screw fixation for unstable sacroiliac joint fracture-dislocation

    Baskin, Kevin M.; Cahill, Ann Marie; Kaye, Robin D. [Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); Born, Christopher T. [Temple University Hospital/Temple Children' s Hospital, Temple Sports Medicine, Marlton, NJ (United States); Grudziak, Jan S. [Children' s Hospital of Pittsburgh, Department of Orthopedic Surgery, Pittsburgh, PA (United States); Towbin, Richard B.

    2004-12-01

    Unstable posterior pelvic ring fractures and dislocations are uncommon but potentially life-threatening injuries in children. Early definitive management reduces risk of immediate complications as well as chronic pain and gait dysfunction. Conventional operative therapy carries substantial risk of extensive blood loss and iatrogenic neurological and vascular injury. Minimally invasive image-guided intervention may further reduce immediate risk and improve long-term outcome. To describe CT-guided closed reduction and internal fixation (CRIF) and review outcomes of unstable fracture-dislocation of the sacroiliac (SI) joint in children. Between 2000 and 2003, three children (two girls, one boy) age 8-14 years were referred to interventional radiology for treatment of unstable SI joint fracture-dislocation not adequately treated with anterior external fixation alone. The three affected SI joints (two left, one right) were treated in a combined approach by pediatric interventional radiologists and orthopedic surgeons, using a percutaneous approach under CT guidance. Over a threaded guiding pin, 7.3 mm cannulated screws were used to achieve stable reduction of the affected SI joints. One screw was removed after slight (2 mm) migration. No neurovascular or other complications occurred. All patients had satisfactory healing with near-anatomic reduction, although recovery of the youngest was delayed by associated spinal injury. Compared to open surgical alternatives, CRIF under CT guidance reduces operating time, decreases blood loss, and allows early definitive fixation and immediate non-weight-bearing mobilization with a low rate of complication for unstable posterior pelvic ring fractures. In addition, CT-guided placement of the guide pin may allow safer screw positioning and may minimize the total number of screws needed to achieve pelvic stability. (orig.)

  4. Beautiful Trees on Unstable Ground: Notes on the Data Problem in Lexicostatistics

    Geisler , Hans; List , Johann-Mattis

    2010-01-01

    The manuscript was submitted in 2010, and is now still waiting for publication as:Geisler, H. and List, J.-M. (to appear in 201?): Beautiful trees on unstable ground: Notes on the dataproblem in lexicostatistics. In: Hettrich, Heinrich (ed.): Die Ausbreitung des Indogermanischen.Thesen aus Sprachwissenschaft, Archäologie und Genetik, Akten der Arbeitstagung derIndogermanischen Gesellschaft Würzburg, 24.-26. September 2009. Wiesbaden: Reichert.Please note that the content of this paper is outd...

  5. Cost-utility of enoxaparin compared with unfractionated heparin in unstable coronary artery disease

    Milne Ruairidh

    2001-10-01

    Full Text Available Abstract Background Low molecular weight heparins hold several advantages over unfractionated heparin including convenience of administration. Enoxaparin is one such heparin licensed in the UK for use in unstable coronary artery disease (unstable stable angina and non-Q wave myocardial infarction. In these patients, two large randomised controlled trials and their meta-analysis showed small benefits for enoxaparin over unfractionated heparin at 30–43 days and potentially at one year. We found no relevant published full economic evaluations, only cost studies, one of which was conducted in the UK. The other studies, from the US, Canada and France, are difficult to interpret since their resource use and costs may not reflect UK practice. Methods We aimed to compare the benefits and costs of short-term treatment (two to eight days with enoxaparin and unfractionated heparin in unstable coronary artery disease. We used published data sources to estimate the incremental cost per quality adjusted life year (QALY, adopting a NHS perspective and using 1998 prices. Results The base case was a 0.013 QALY gain and net cost saving of £317 per person treated with enoxaparin instead of unfractionated heparin. All but one sensitivity analysis showed net savings and QALY gains, the exception (the worst case being a cost per QALY of £3,305. Best cases were a £495 saving and 0.013 QALY gain, or a £317 saving and 0.014 QALY gain per person. Conclusions Enoxaparin appears cost saving compared with unfractionated heparin in patients with unstable coronary artery disease. However, cost implications depend on local revascularisation practice.

  6. Calculation of a CO sub 2 gasdynamic laser with selective thermal excitation and an unstable resonator

    Kuz' min, A.I.; Lavrov, A.V.; Chernysheva, N.V. (Leningradskii Gosudarstvennyi Universitet, Leningrad (USSR))

    1989-03-01

    The problem of calculating an unstable telescopic resonator for a CO{sub 2} gasdynamic laser with selective thermal excitation is studied. Parabolized Navier-Stokes equations and equations of field propagation in the resonator are used to describe the GDL in the geometric optic approximation. The efficiency is studied as a function of the magnification factor and of the distance between the mirrors. 19 refs.

  7. Suspended Particulates Concentration (PM10 under Unstable Atmospheric Conditions over Subtropical Urban Area (Qena, Egypt

    M. El-Nouby Adam

    2013-01-01

    Full Text Available The main purpose of this study is to evaluate the suspended particulates (PM10 in the atmosphere under unstable atmospheric conditions. The variation of PM10 was investigated and primary statistics were employed. The results show that, the PM10 concentrations values ranged from 6.00 to 646.74 μg m−3. The average value of PM10 is equal to 114.32 μg m−3. The high values were recorded in April and May (155.17 μg m−3 and 171.82 μg m−3, respectively and the low values were noted in February and December (73.86 μg m−3 and 74.05 μg m−3, respectively. The average value of PM10 of the hot season (125.35 × 10−6 g m−3 was higher than its value for the cold season (89.27 μg m−3. In addition, the effect of weather elements (air temperature, humidity and wind on the concentration of PM10 was determined. The multiple R between PM10 and these elements ranged from 0.05 to 0.47 and its value increased to reach 0.73 for the monthly average of the database used. Finally, the PM10 concentrations were grouped depending on their associated atmospheric stability class. These average values were equal to 122.80 ± 9 μg m−3 (highly unstable or convective, 109.37 ± 12 μg m−3 (moderately unstable and 104.42 ± 15 μg m−3 (slightly unstable.

  8. Influence of an unstable shoe on compensatory postural adjustments: An experimental evaluation

    Andreia S. P. Sousa; Rui Macedo; Rubim Santos; João Manuel R. S. Tavares

    2010-01-01

    This study attempted to evaluate the influence of using an unstable shoe in muscle re-cruitment strategies and center of pressure (CoP) displacement after the application of an external perturba-tion. Fourteen healthy female subjects participated in this study. The electromyographic activity of medial ga-strocnemius, tibialis anterior, rectus femoris, biceps femoris, rectus abdominis and erector spinae muscles and the kinetic values to calculate the CoP were collected and analyzed after the a...

  9. Closed reduction with CT-guided screw fixation for unstable sacroiliac joint fracture-dislocation

    Baskin, Kevin M.; Cahill, Ann Marie; Kaye, Robin D.; Born, Christopher T.; Grudziak, Jan S.; Towbin, Richard B.

    2004-01-01

    Unstable posterior pelvic ring fractures and dislocations are uncommon but potentially life-threatening injuries in children. Early definitive management reduces risk of immediate complications as well as chronic pain and gait dysfunction. Conventional operative therapy carries substantial risk of extensive blood loss and iatrogenic neurological and vascular injury. Minimally invasive image-guided intervention may further reduce immediate risk and improve long-term outcome. To describe CT-guided closed reduction and internal fixation (CRIF) and review outcomes of unstable fracture-dislocation of the sacroiliac (SI) joint in children. Between 2000 and 2003, three children (two girls, one boy) age 8-14 years were referred to interventional radiology for treatment of unstable SI joint fracture-dislocation not adequately treated with anterior external fixation alone. The three affected SI joints (two left, one right) were treated in a combined approach by pediatric interventional radiologists and orthopedic surgeons, using a percutaneous approach under CT guidance. Over a threaded guiding pin, 7.3 mm cannulated screws were used to achieve stable reduction of the affected SI joints. One screw was removed after slight (2 mm) migration. No neurovascular or other complications occurred. All patients had satisfactory healing with near-anatomic reduction, although recovery of the youngest was delayed by associated spinal injury. Compared to open surgical alternatives, CRIF under CT guidance reduces operating time, decreases blood loss, and allows early definitive fixation and immediate non-weight-bearing mobilization with a low rate of complication for unstable posterior pelvic ring fractures. In addition, CT-guided placement of the guide pin may allow safer screw positioning and may minimize the total number of screws needed to achieve pelvic stability. (orig.)

  10. The effect of unstable sandals on instability in gait in healthy female subjects.

    Price, Carina; Smith, Laura; Graham-Smith, Philip; Jones, Richard

    2013-07-01

    Unstable footwear generally lacks thorough peer-review published research to support concepts and marketing claims. The purpose of this study was to investigate the instability induced by four (FitFlop, Masai Barefoot Technology, Reebok Easy-Tone and Skechers Tone-Ups) commercially available unstable sandals and one stable control sandal (Earth) in walking in 15 females (mean±SD age was 29±6.7 years, mass 62.6±6.9kg and height 167.1±4.2cm). Three-dimensional motion with synchronised electromyography and kinetic data were collected. Walking speed and step length remained consistent between conditions, however double support time decreased in Masai Barefoot Technology. Centre of pressure data identified no consistent difference between the stable control and the unstable sandals, however Masai Barefoot Technology reduced the anterior-posterior range of centre of pressure. Muscle activity differed significantly at the ankle in the unstable footwear. FitFlop, Reebok and Skechers increased peroneal activity during pre-swing, whereas Masai Barefoot Technology increased medial gastrocnemius and decreased tibialis anterior activity in loading response and mid-stance. The larger rocker sole of the Masai Barefoot Technology altered gait and muscle activation with regard to braking and progression in the sagittal plane. Reebok, Skechers and FitFlop, with softer, less stable foreparts increased evertor action at toe-off, having their effect in the coronal plane. The study highlighted that any instability induced by the shoes is design-specific. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Treatment options for unstable trochanteric fractures: Screw or helical proxima femoral nail.

    Bajpai, Jeetendra; Maheshwari, Rajesh; Bajpai, Akansha; Saini, Sumit

    2015-01-01

    To compare treatment outcome of screw proximal femoral nail (PFN) system with that of a helical PFN. The study included 77 patients with closed unstable intertrochanteric fracture classified as AO 31A2&31A3, between June 2008 to August 2011. Inclusion criteria were: all mature skeletons above 50 years of age; closed unstable trochanteric fracture classified as AO 31A2&A3. Exclusion criteria were: immature skeleton, pathological fracture of any cause other than osteoporosis, inability to walk inde- pendently prior to injury. Patients were randomized to 2 treatment groups based on admission sequence. Forty patients were treated with screw PFN and thirty seven were treated with helical PFN. Both groups were similar in respect of time of surgery, blood loss and functional assessment and duration of hospitalization. In screw PFN group 2 patients had superficial wound infection, 1 patient had persistent hip pain and 1 patient had shortening>1 cm buttrochanteric fractures even in Indian patients where the bones are narrow and neck diameter is small. It is an implant of choice for osteoporotic and unstable trochanteric fractures.

  12. On the persistence of unstable bump-on-tail electron velocity distributions in the earth's foreshock

    Klimas, A.J.; Fitzenreiter, R.J.

    1988-01-01

    Further evidence for the persistence of bump-on-tail unstable reduced velocity distribution in the Earth's electron foreshock is presented. This persistence contradicts our understanding of quasi-linear saturation of the bump-on-tail instability; the distributions should be stabilized through velocity space diffusion too quickly to allow an observation of their unstable form. A modified theory for the saturation of the bump-on-tail instability in the Earth's foreshock is proposed and examined using numerical simulation and quasi-linear theoretical techniques. It is argued the mechanism due to Filbert and Kellogg and to Cairns which is responsible for the creation of the bump-on-tail velocity distribution in the foreshock is still operative during the evolution of the bump-on-tail instability. The saturated state of the plasma must represent a balance between this creation mechanism and velocity space diffusion; the saturated state is not determined by velocity space diffusion alone. Thus the velocity distribution of the saturated stat may still appear bump-on-tail unstable to standard linear analysis which does not take the creation mechanism into account. The bump-on-tail velocity distributions in the foreshock would then represent the state of the plasma after saturation of the bump-on-tail instability, not before

  13. Immediate percutaneous sacroiliac screw insertion for unstable pelvic fractures: is it safe enough?

    Acker, A; Perry, Z H; Blum, S; Shaked, G; Korngreen, A

    2018-04-01

    The purpose of this study was to compare the results of immediate and delayed percutaneous sacroiliac screws surgery for unstable pelvic fractures, regarding technical results and complication rate. Retrospective study. The study was conducted at the Soroka University Medical center, Beer Sheva, Israel, which is a level 1 trauma Center. 108 patients with unstable pelvic injuries were operated by the orthopedic department at the Soroka University Medical Center between the years 1999-2010. A retrospective analysis found 50 patients with immediate surgery and 58 patients with delayed surgery. Preoperative and postoperative imaging were analyzed and data was collected regarding complications. All patients were operated on by using the same technique-percutaneous fixation of sacroiliac joint with cannulated screws. The study's primary outcome measure was the safety and quality of the early operation in comparison with the late operation. A total of 156 sacroiliac screws were inserted. No differences were found between the immediate and delayed treatment groups regarding technical outcome measures (P value = 0.44) and complication rate (P value = 0.42). The current study demonstrated that immediate percutaneous sacroiliac screw insertion for unstable pelvic fractures produced equally good technical results, in comparison with the conventional delayed operation, without additional complications.

  14. Nd:YAG (2 omega) pumped dye laser using self-filtering unstable resonator

    Rahimian, K; Hariri, H

    2002-01-01

    A self-filtering unstable resonator with a magnification of M=-3 in a Nd:YAG (2 omega) dye laser has been studied. The dye solution is Rhodamine 6 G in alcohol with the concentration of 5*10 sub - 3 Mol/lit. The spatial intensity distribution of the resonator has been compared has been compared with that of a plane-parallel resonator of equal length. The output energy in both configurations are comparable (20 mu J ,and 26 mu J ,respectively). A significant difference between these two resonators is the laser beam divergence, where beam divergences of 0.77 mrad for the self-filtering unstable resonator and 1.6 mrad for the plane-parallel resonator have been measured. The brightness corresponding to these two resonators are 1.5* 10 sub 1 1 and 2.2* 10 sub 1 0W.cm sub - 2.Sr sub - 1, and the pulse widths are 7 and 17 ns, respectively. These figures show clearly that laser resonator based on the self-filtering unstable resonator design an increase the laser brightness a factor of 10, with a beam divergence of a f...

  15. Treatment of unstable intraarticular fracture of distal radius: POP casting with external fixation.

    ur Rahman, Obaid; Khan, Mohammad Qadeem; Rasheed, Haroon; Ahmad, Saleem

    2012-04-01

    To compare radiological and functional outcome of external fixation and distraction with conservative Plaster of Paris (POP) cast for unstable intra-articular fractures of the distal radius. The study was conducted on 60 patients with unstable intra-articular fracture of distal radius who reported to emergency or outpatient Orthopaedic Surgery department of Benazir Bhutto Hospital, Rawalpindi, between March and August 2007. They were divided into two equal groups: Group A and Group B, treated by Plaster of Paris cast, and external fixation with distraction respectively. The functional outcome in terms of freedom from pain, range of movement, grip power and deformity, and the radiological outcome of radial length, incongruity and radio-ulnar joint position were analysed at three months follow-up using a 3-point scoring scale. In Group A, 1 (3%) patient showed excellent result, 8 (27%) patients good results, 19 (63%) patients fair results and 2 (7%) patients poor result. In Group B, 14 (47%) patients showed excellent results, 11 (37%) patients good results, 4 (13%) patients fair results and 1 (3%) patient poor result. The outcome score of the Group B patients was significantly better compared to the Group A patients (p value advantages over conventional Plaster of Paris cast in the treatment of unstable intra-articular fractures of distal radius.

  16. Finite-width effects in unstable-particle production at hadron colliders

    Falgari, P.; Signer, A.; Zuerich Univ.

    2013-03-01

    We present a general formalism for the calculation of finite-width contributions to the differential production cross sections of unstable particles at hadron colliders. In this formalism, which employs an effective-theory description of unstable-particle production and decay, the matrix element computation is organized as a gauge-invariant expansion in powers of Γ X /m X , with Γ X and m X the width and mass of the unstable particle. This framework allows for a systematic inclusion of off-shell and non-factorizable effects whilst at the same time keeping the computational effort minimal compared to a full calculation in the complex-mass scheme. As a proof-of-concept example, we give results for an NLO calculation of top-antitop production in the q anti q partonic channel. As already found in a similar calculation of single-top production, the finite-width effects are small for the total cross section, as expected from the naive counting ∝Γ t /m t ∝1%. However, they can be sizeable, in excess of 10%, close to edges of certain kinematical distributions. The dependence of the results on the mass renormalization scheme, and its implication for a precise extraction of the top-quark mass, is also discussed.

  17. Unstable chromosome aberrations on peripheral blood lymphocytes from patients with cervical uterine cancer following radiotherapy

    Magnata, Simey de Souza Leao Pereira

    2002-09-01

    Absorbed dose determination is an important step for risk assessment related to an exposure to ionizing radiation. However, physical dosimetry cannot be always performed, principally in the case of retrospective estimates. In this context, the use of bioindicators (biological effects) has been proposed, which defines the so-called biological dosimetry. In particular, scoring of unstable chromosomes aberrations (dicentrics, centric rings and fragments) of peripheral blood lymphocytes, while is the most reliable biological method for estimating individual exposure to ionizing radiation. In this work, blood samples from 5 patients, with cervical uterine cancer, were evaluated after partial-body radiotherapy with a source of 69 Co. For this, conventional cytogenetic method was employed, based on Giemsa coloration and fluorescence in situ hybridization, in order to correlate the frequency of unstable chromosome aberrations of blood lymphocytes with absorbed dose, as a result of the radiotherapy. A good agreement was observed between the frequency of chromosome aberrations scored and the values of dose previously calculated by physical dosimetry during patient's radiotherapy. The results presented in this work point out the importance of concerning analyses of unstable chromosome aberrations as biological dosimeter in the investigation of partial-body exposure to ionizing radiation. (author)

  18. Use of unstable chromosome aberrations for biological dosimetry after the first postirradiation mitosis

    Doloy, M.T.; Malarbet, J.L.; Guedeney, G.; Bourguignon, M.; Leroy, A.; Reillaudou, M.; Masse, R.

    1991-01-01

    The loss of unstable chromosome aberrations after the first postirradiation mitosis makes their use difficult in radiation dosimetry. We describe here a method which, in a cell population observed at this stage, allows retrospective estimation of the frequencies of the unstable aberrations induced at the time of irradiation, and their use as a dosimeter. The laws controlling the behavior of unstable aberrations during mitosis were defined from a large-scale experiment on irradiated human lymphocytes. For cells undergoing the first, second, or third mitosis after irradiation, relationships were determined between the frequency, at irradiation time, of acentric fragments not arising from formation of dicentrics or rings, and the ratio of dicentrics and centric rings appearing without acentric fragments to the total number of dicentrics plus rings. On the basis of this ratio, the method described here provides an assessment of the postirradiation mitotic activity in a cell population. This assessment permitted estimation of the cell distribution and frequency of dicentrics plus centric rings, and of the frequency of acentric fragments at the time of irradiation. The use of this method for retrospective dosimetry after whole-body irradiation under various conditions of exposure is illustrated

  19. Finite-width effects in unstable-particle production at hadron colliders

    Falgari, P. [Utrecht Univ. (Netherlands). Inst. for Theoretical Physics; Utrecht Univ. (Netherlands). Spinoza Inst.; Papanastasiou, A.S. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Signer, A. [Paul Scherrer Institut, Villigen (Switzerland); Zuerich Univ. (Switzerland). Inst. for Theoretical Physics

    2013-03-15

    We present a general formalism for the calculation of finite-width contributions to the differential production cross sections of unstable particles at hadron colliders. In this formalism, which employs an effective-theory description of unstable-particle production and decay, the matrix element computation is organized as a gauge-invariant expansion in powers of {Gamma}{sub X}/m{sub X}, with {Gamma}{sub X} and m{sub X} the width and mass of the unstable particle. This framework allows for a systematic inclusion of off-shell and non-factorizable effects whilst at the same time keeping the computational effort minimal compared to a full calculation in the complex-mass scheme. As a proof-of-concept example, we give results for an NLO calculation of top-antitop production in the q anti q partonic channel. As already found in a similar calculation of single-top production, the finite-width effects are small for the total cross section, as expected from the naive counting {proportional_to}{Gamma}{sub t}/m{sub t}{proportional_to}1%. However, they can be sizeable, in excess of 10%, close to edges of certain kinematical distributions. The dependence of the results on the mass renormalization scheme, and its implication for a precise extraction of the top-quark mass, is also discussed.

  20. Accumulation of unstable periodic orbits and the stickiness in the two-dimensional piecewise linear map.

    Akaishi, A; Shudo, A

    2009-12-01

    We investigate the stickiness of the two-dimensional piecewise linear map with a family of marginal unstable periodic orbits (FMUPOs), and show that a series of unstable periodic orbits accumulating to FMUPOs plays a significant role to give rise to the power law correlation of trajectories. We can explicitly specify the sticky zone in which unstable periodic orbits whose stability increases algebraically exist, and find that there exists a hierarchy in accumulating periodic orbits. In particular, the periodic orbits with linearly increasing stability play the role of fundamental cycles as in the hyperbolic systems, which allows us to apply the method of cycle expansion. We also study the recurrence time distribution, especially discussing the position and size of the recurrence region. Following the definition adopted in one-dimensional maps, we show that the recurrence time distribution has an exponential part in the short time regime and an asymptotic power law part. The analysis on the crossover time T(c)(*) between these two regimes implies T(c)(*) approximately -log[micro(R)] where micro(R) denotes the area of the recurrence region.

  1. Bench Press Upper-Body Muscle Activation Between Stable and Unstable Loads.

    Dunnick, Dustin D; Brown, Lee E; Coburn, Jared W; Lynn, Scott K; Barillas, Saldiam R

    2015-12-01

    The bench press is one of the most commonly used upper-body exercises in training and is performed with many different variations, including unstable loads (ULs). Although there is much research on use of an unstable surface, there is little to none on the use of an UL. The purpose of this study was to investigate muscle activation during the bench press while using a stable load (SL) vs. UL. Twenty resistance-trained men (age = 24.1 ± 2 years; ht = 177.5 ± 5.8 cm; mass = 88.7 ± 13.7 kg) completed 2 experimental conditions (SL and UL) at 2 different intensities (60 and 80% one repetition maximum). Unstable load was achieved by hanging 16 kg kettlebells by elastic bands from the end of the bar. All trial lifts were set to a 2-second cadence with a slight pause at the bottom. Subjects had electrodes attached to 5 muscles (pectoralis major, anterior deltoid, medial deltoid, triceps brachii, and latissimus dorsi) and performed 3 isometric bench press trials to normalize electromyographic data. All 5 muscles demonstrated significantly greater activation at 80% compared with 60% load and during concentric compared with eccentric actions. These results suggest that upper body muscle activation is not different in the bench press between UL and SL. Therefore, coaches should use their preference when designing training programs.

  2. Efficacy evaluation of fluoxetine combined with conventional drug treatment on unstable angina patients complicated with depression

    Chun-Hua Liao

    2015-01-01

    Objective:To study the efficacy of fluoxetine combined with conventional drug treatment on unstable angina patients complicated with depression. Methods:120 cases of unstable angina patients with depression were randomly divided into two groups. The anti-depression group received fluoxetine combined with conventional drug therapy; the conventional group received conventional drug therapy. Then contents of monoamine neurotransmitters and their metabolites, antioxidants and inflammatory mediators of both groups were compared. Results:Serum monoamine neurotransmitters NE, 5-HT and HA levels of the anti-depression group were higher than those of the conventional group and metabolites 5-HIAA and HVA contents were lower than those of the conventional group; serum SOD, CAT, GSH and HSP-70 contents of the anti-depression group were higher than those of the conventional group, and hs-CRP, MMP9, MCP1 and HMGB1 contents were lower than those of the conventional group. Conclusion:Fluoxetine combined with conventional drug therapy can increase the contents of monoamine neurotransmitters and antioxidants, and reduce oxidative stress response and inflammatory response; it is an ideal method for treating unstable angina complicated with depression.

  3. Beneficial effect of nitrates on myocardial glucose utilization in unstable angina pectoris

    Araujo, L.I.; Camici, P.; Spinks, T.; Jones, T.; Maseri, A.

    1987-01-01

    Myocardial uptake of the glucose analog F-18-2-fluoro-2-deoxy-D-glucose (FDG) was assessed by positron emission tomography in 6 normal volunteers, 7 patients with chronic stable angina and 22 patients with unstable angina at rest in fasting conditions. Regional myocardial perfusion was assessed by rubidium-82. The study was repeated a few days later after intravenous infusion of isosorbide dinitrate. FDG uptake was similar in control subjects and patients with stable angina (0.023 +/- 0.032 vs 0.012 +/- 0.008 mol/ml/min, p less than 0.42) but was about 4-fold higher on the average in patients with unstable angina (0.084 +/- 0.047, p less than 0.01). The severity of coronary obstructions in stable and unstable angina patients was similar. The increased uptake involved the whole heart, including areas not distal to critically stenosed vessels; it was not associated with reduced myocardial perfusion and was not related to a recent episode of transient ischemia as assessed by symptoms and by Holter monitoring. After continuous infusion of nitrates, FDG uptake was consistently and significantly reduced toward normal levels both in areas perfused by critically stenosed coronary arteries and by noncritically stenosed vessels

  4. Conventional radiation-biological dosimetry using frequencies of unstable chromosome aberrations

    Ramalho, Adriana T.; Costa, Maria Lucia P.; Oliveira, Monica S.

    1998-01-01

    Frequency of chromosome aberrations detected by conventional cytogenetics is a very useful parameter in biological radiodosimetry. It can be used for estimating absorbed doses in individuals working with radioactive sources and individuals accidentally exposed to radiation. In the first case subjects wear physical dosimeters as a routine safety habit. The laboratory at the Institute of Radioprotection and Dosimetry (IRD, Brazil) has been using conventional cytogenetic analysis to complement data obtained by physical dosimetry since 1983. Until now, more than one hundred cases were investigated where individual physical dosimeters detected occupational exposure (above the safety limits allowed). In total, only 34% of these cases were confirmed by conventional cytogenetic dosimetry. Also, conventional cytogenetic analysis following the radiation accident of Goiania (Brazil) in 1987 have been used. Peripheral lymphocytes from 129 exposed or potentially exposed individuals were analyzed for the frequencies of unstable chromosomal aberrations (dicentrics, centric rings and acentrics fragments) to estimate absorbed radiation doses. During the emergency period, doses were estimated to help immediate medical treatment using in vitro calibration curves produced before the accident. Later on, doses were assessed once more using new in vitro calibration curves. A drawback of this technique is that unstable aberrations are lost after exposure. To investigate the mean lifespan of lymphocytes containing dicentric and ring aberrations, we have followed 15 victims of the Goiania accident over all these years. Results suggest that the disappearance of unstable aberrations is dose-dependent. This could explain the variation in the results found among studies in this field

  5. Conventional radiation-biological dosimetry using frequencies of unstable chromosome aberrations

    Ramalho, Adriana T.; Costa, Maria Lucia P.; Oliveira, Monica S. [Institute of Radioprotection and Dosimetry (IRD), National Commission of Nuclear Energy (CNEN), Av. Salvador Allende, Cx. P. 37750, Rio de Janeiro 22.780-160 (Brazil)

    1998-08-03

    Frequency of chromosome aberrations detected by conventional cytogenetics is a very useful parameter in biological radiodosimetry. It can be used for estimating absorbed doses in individuals working with radioactive sources and individuals accidentally exposed to radiation. In the first case subjects wear physical dosimeters as a routine safety habit. The laboratory at the Institute of Radioprotection and Dosimetry (IRD, Brazil) has been using conventional cytogenetic analysis to complement data obtained by physical dosimetry since 1983. Until now, more than one hundred cases were investigated where individual physical dosimeters detected occupational exposure (above the safety limits allowed). In total, only 34% of these cases were confirmed by conventional cytogenetic dosimetry. Also, conventional cytogenetic analysis following the radiation accident of Goiania (Brazil) in 1987 have been used. Peripheral lymphocytes from 129 exposed or potentially exposed individuals were analyzed for the frequencies of unstable chromosomal aberrations (dicentrics, centric rings and acentrics fragments) to estimate absorbed radiation doses. During the emergency period, doses were estimated to help immediate medical treatment using in vitro calibration curves produced before the accident. Later on, doses were assessed once more using new in vitro calibration curves. A drawback of this technique is that unstable aberrations are lost after exposure. To investigate the mean lifespan of lymphocytes containing dicentric and ring aberrations, we have followed 15 victims of the Goiania accident over all these years. Results suggest that the disappearance of unstable aberrations is dose-dependent. This could explain the variation in the results found among studies in this field

  6. Eos modeling and reservoir simulation study of bakken gas injection improved oil recovery in the elm coulee field, Montana

    Pu, Wanli

    The Bakken Formation in the Williston Basin is one of the most productive liquid-rich unconventional plays. The Bakken Formation is divided into three members, and the Middle Bakken Member is the primary target for horizontal wellbore landing and hydraulic fracturing because of its better rock properties. Even with this new technology, the primary recovery factor is believed to be only around 10%. This study is to evaluate various gas injection EOR methods to try to improve on that low recovery factor of 10%. In this study, the Elm Coulee Oil Field in the Williston Basin was selected as the area of interest. Static reservoir models featuring the rock property heterogeneity of the Middle Bakken Member were built, and fluid property models were built based on Bakken reservoir fluid sample PVT data. By employing both compositional model simulation and Todd-Longstaff solvent model simulation methods, miscible gas injections were simulated and the simulations speculated that oil recovery increased by 10% to 20% of OOIP in 30 years. The compositional simulations yielded lower oil recovery compared to the solvent model simulations. Compared to the homogeneous model, the reservoir model featuring rock property heterogeneity in the vertical direction resulted in slightly better oil recovery, but with earlier CO2 break-through and larger CO2 production, suggesting that rock property heterogeneity is an important property for modeling because it has a big effect on the simulation results. Long hydraulic fractures shortened CO2 break-through time greatly and increased CO 2 production. Water-alternating-gas injection schemes and injection-alternating-shut-in schemes can provide more options for gas injection EOR projects, especially for gas production management. Compared to CO2 injection, separator gas injection yielded slightly better oil recovery, meaning separator gas could be a good candidate for gas injection EOR; lean gas generated the worst results. Reservoir

  7. Safety and efficacy of angioplasty with intracoronary stenting in patients with unstable coronary syndromes. Comparison with stable coronary syndromes

    Luís C. L. Correia

    2000-06-01

    Full Text Available OBJECTIVE: To assess safety and efficacy of coronary angioplasty with stent implantation in unstable coronary syndromes. METHODS: Retrospective analysis of in-hospital and late evolution of 74 patients with unstable coronary syndromes (unstable angina or infarction without elevation of the ST segment undergoing coronary angioplasty with stent placement. These 74 patients were compared with 31 patients with stable coronary syndromes (stable angina or stable silent ischemia undergoing the same procedure. RESULTS: No death and no need for revascularization of the culprit artery occurred in the in-hospital phase. The incidences of acute non-Q-wave myocardial infarction were 1.4% and 3.2% (p=0.6 in the unstable and stable coronary syndrome groups, respectively. In the late follow-up (11.2±7.5 months, the incidences of these events combined were 5.7% in the unstable coronary syndrome group and 6.9% (p=0.8 in the stable coronary syndrome group. In the multivariate analysis, the only variable with a tendency to significance as an event predictor was diabetes mellitus (p=0.07; OR=5.2; 95% CI=0.9-29.9. CONCLUSION: The in-hospital and late evolutions of patients with unstable coronary syndrome undergoing angioplasty with intracoronary stent implantation are similar to those of the stable coronary syndrome group, suggesting that this procedure is safe and efficacious when performed in unstable coronary syndrome patients.

  8. A Biomechanical Study Comparing Helical Blade with Screw Design for Sliding Hip Fixations of Unstable Intertrochanteric Fractures

    Qiang Luo

    2013-01-01

    Full Text Available Dynamic hip screw (DHS is a well-established conventional implant for treating intertrochanteric fracture. However, revision surgery sometimes still occurs due to the cutting out of implants. A helical blade instead of threaded screw (DHS blade was designed to improve the fixation power of the osteoporotic intertrochanteric fracture. In this study, the biomechanical properties of DHS blade compared to the conventional DHS were evaluated using an unstable AO/OTA 31-A2 intertrochanteric fracture model. Fifty synthetic proximal femoral bone models with such configuration were fixed with DHS and DHS blade in five different positions: centre-centre (CC, superior-centre (SC, inferior-center (IC, centre-anterior (CA, and centre-posterior (CP. All models had undergone mechanical compression test, and the vertical and rotational displacements were recorded. The results showed that DHS blade had less vertical or rotational displacement than the conventional DHS in CC, CA, and IC positions. The greatest vertical and rotational displacements were found at CP position in both groups. Overall speaking, DHS blade was superior in resisting vertical or rotational displacement in comparison to conventional DHS, and the centre-posterior position had the poorest performance in both groups.

  9. A high-power diode-laser-pumped CW Nd:YAG laser using a stable-unstable resonator

    Mudge, M.; Ostermeyer, P.; Veitch, J.; Munch, J.; Hamilton, M.W.

    2000-01-01

    Full text: The design and operation of a power-scalable diode-laser-pumped CW Nd:YAG zigzag slab laser that uses a stable-unstable resonator with a graded reflectivity mirror as an output coupler is described. We demonstrate control of the thermal lens strength in the unstable plane and weak thermal lensing in the stable plane that is independent of pump power, vital for efficient scalability. This enabled CW operation of the stable-unstable resonator with excellent near- and far-field beam quality

  10. A Numerical Study of Nonlinear Nonhydrostatic Conditional Symmetric Instability in a Convectively Unstable Atmosphere.

    Seman, Charles J.

    1994-06-01

    Nonlinear nonhydrostatic conditional symmetric instability (CSI) is studied as an initial value problem using a two-dimensional (y, z)nonlinear, nonhydrostatic numerical mesoscale/cloud model. The initial atmosphere for the rotating, baroclinic (BCF) simulation contains large convective available potential energy (CAPE). Analytical theory, various model output diagnostics, and a companion nonrotating barotropic (BTNF) simulation are used to interpret the results from the BCF simulation. A single warm moist thermal initiates convection for the two 8-h simulations.The BCF simulation exhibited a very intricate life cycle. Following the initial convection, a series of discrete convective cells developed within a growing mesoscale circulation. Between hours 4 and 8, the circulation grew upscale into a structure resembling that of a squall-line mesoscale convective system (MCS). The mesoscale updrafts were nearly vertical and the circulation was strongest on the baroclinically cool side of the initial convection, as predicted by a two-dimensional Lagrangian parcel model of CSI with CAPE. The cool-side mesoscale circulation grew nearly exponentially over the last 5 h as it slowly propagated toward the warm air. Significant vertical transport of zonal momentum occurred in the (multicellular) convection that developed, resulting in local subgeostrophic zonal wind anomalies aloft. Over time, geostrophic adjustment acted to balance these anomalies. The system became warm core, with mesohigh pressure aloft and mesolow pressure at the surface. A positive zonal wind anomaly also formed downstream from the mesohigh.Analysis of the BCF simulation showed that convective momentum transport played a key role in the evolution of the simulated MCS, in that it fostered the development of the nonlinear CSI on mesoscale time scales. The vertical momentum transport in the initial deep convection generated a subgeostrophic zonal momentum anomaly aloft; the resulting imbalance in pressure

  11. Modeling the Impact of Deformation on Unstable Miscible Displacements in Porous Media

    Santillán, D.; Cueto-Felgueroso, L.

    2014-12-01

    Coupled flow and geomechanics is a critical research challenge in engineering and the geosciences. The simultaneous flow of two or more fluids with different densities or viscosities through deformable media is ubiquitous in environmental, industrial, and biological processes, including the removal of non-aqueous phase liquids from underground water bodies, the geological storage of CO2, and current challenges in energy technologies, such as enhanced geothermal systems, unconventional hydrocarbon resources or enhanced oil recovery techniques. Using numerical simulation, we study the interplay between viscous-driven flow instabilities (viscous fingering) and rock mechanics, and elucidate the structure of the displacement patterns as a function of viscosity contrast, injection rate and rock mechanical properties. Finally, we discuss the role of medium deformation on transport and mixing processes in porous media.

  12. Simultaneous inversion of seismic velocity and moment tensor using elastic-waveform inversion of microseismic data: Application to the Aneth CO2-EOR field

    Chen, Y.; Huang, L.

    2017-12-01

    Moment tensors are key parameters for characterizing CO2-injection-induced microseismic events. Elastic-waveform inversion has the potential to providing accurate results of moment tensors. Microseismic waveforms contains information of source moment tensors and the wave propagation velocity along the wavepaths. We develop an elastic-waveform inversion method to jointly invert the seismic velocity model and moment tensor. We first use our adaptive moment-tensor joint inversion method to estimate moment tensors of microseismic events. Our adaptive moment-tensor inversion method jointly inverts multiple microseismic events with similar waveforms within a cluster to reduce inversion uncertainty for microseismic data recorded using a single borehole geophone array. We use this inversion result as the initial model for our elastic-waveform inversion to minimize the cross-correlated-based data misfit between observed data and synthetic data. We verify our method using synthetic microseismic data and obtain improved results of both moment tensors and seismic velocity model. We apply our new inversion method to microseismic data acquired at a CO2-enhanced oil recovery field in Aneth, Utah, using a single borehole geophone array. The results demonstrate that our new inversion method significantly reduces the data misfit compared to the conventional ray-theory-based moment-tensor inversion.

  13. Cost effectiveness and value of information analyses of islet cell transplantation in the management of 'unstable' type 1 diabetes mellitus.

    Wallner, Klemens; Shapiro, A M James; Senior, Peter A; McCabe, Christopher

    2016-04-09

    Islet cell transplantation is a method to stabilize type 1 diabetes patients with hypoglycemia unawareness and unstable blood glucose levels by reducing insulin dependency and protecting against severe hypoglycemia through restoring endogenous insulin secretion. This study analyses the current cost-effectiveness of this technology and estimates the value of further research to reduce uncertainty around cost-effectiveness. We performed a cost-utility analysis using a Markov cohort model with a mean patient age of 49 to simulate costs and health outcomes over a life-time horizon. Our analysis used intensive insulin therapy (IIT) as comparator and took the provincial healthcare provider perspective. Cost and effectiveness data for up to four transplantations per patient came from the University of Alberta hospital. Costs are expressed in 2012 Canadian dollars and effectiveness in quality-adjusted life-years (QALYs) and life years. To characterize the uncertainty around expected outcomes, we carried out a probabilistic sensitivity analysis within the Bayesian decision-analytic framework. We performed a value-of-information analysis to identify priority areas for future research under various scenarios. We applied a structural sensitivity analysis to assess the dependence of outcomes on model characteristics. Compared to IIT, islet cell transplantation using non-generic (generic) immunosuppression had additional costs of $150,006 ($112,023) per additional QALY, an average gain of 3.3 life years, and a probability of being cost-effective of 0.5 % (28.3 %) at a willingness-to-pay threshold of $100,000 per QALY. At this threshold the non-generic technology has an expected value of perfect information (EVPI) of $260,744 for Alberta. This increases substantially in cost-reduction scenarios. The research areas with the highest partial EVPI are costs, followed by natural history, and effectiveness and safety. Current transplantation technology provides substantial

  14. Decreased soluble cell adhesion molecules after tirofiban infusion in patients with unstable angina pectoris

    Aliyev Emil

    2004-04-01

    Full Text Available Abstract Aim The inflammatory response, initiated by neutrophil and monocyte adhesion to endothelial cells, is important in the pathogenesis of acute coronary syndromes. Platelets play an important role in inflammatory process by interacting with monocytes and neutrophils. In this study, we investigated the effect of tirofiban on the levels of cell adhesion molecules (soluble intercellular adhesion molecule-1, sICAM-1, and vascular cell adhesion molecule-1, sVCAM-1 in patients with unstable angina pectoris (AP. Methods Thirty-five patients with unstable AP (Group I, ten patients with stable AP (Group II and ten subjects who had angiographycally normal coronary arteries (Group III were included the study. Group I was divided into two subgroups for the specific treatment regimens: Group IA (n = 15 received tirofiban and Group IB (n = 20 did not. Blood samples for investigating the cell adhesion molecules were drawn at zero time (baseline; 0 h in all patients and at 72 h in Group I. Results The baseline levels of sICAM-1 and sVCAM-1 were higher in Group I than in Groups II and III. They were higher in Group IA than in Group IB. However, the sICAM-1 and sVCAM-1 levels decreased significantly in Group IA after tirofiban infusion. In contrast, these levels remained unchanged or were increased above the baseline value in Group IB at 72 h. Conclusion The levels of cell adhesion molecules in patients with unstable AP decreased significantly after tirofiban infusion. Inhibition of platelet function by specific glycoprotein IIb/IIIa antagonists may decrease platelet-mediated inflammation and the ischemic end-point.

  15. Unstable bodyweight and incident type 2 diabetes mellitus: A meta-analysis.

    Kodama, Satoru; Fujihara, Kazuya; Ishiguro, Hajime; Horikawa, Chika; Ohara, Nobumasa; Yachi, Yoko; Tanaka, Shiro; Shimano, Hitoshi; Kato, Kiminori; Hanyu, Osamu; Sone, Hirohito

    2017-07-01

    The present meta-analysis aimed to clarify the association of unstable bodyweight with the risk of type 2 diabetes mellitus, an association that has been controversial among longitudinal studies. An electronic literature search using EMBASE and MEDLINE was followed up to 31 August 2016. The relative risks (RRs) of type 2 diabetes mellitus in individuals with unstable bodyweight were pooled using the inverse variance method. Eight studies were eligible for the meta-analysis. The median duration of measurements of weight change and follow-up years for ascertaining type 2 diabetes mellitus were 13.5 and 9.4 years, respectively. The pooled RR for the least vs most stable category was 1.33 (95% confidence interval 1.12-1.57). Between-study heterogeneity was statistically significant (P = 0.048). Whether type 2 diabetes mellitus was ascertained by blood testing explained 66.0% of the variance in the logarithm of RR (P = 0.02). In three studies in which blood testing was carried out, type 2 diabetes mellitus risk was not significant (RR 1.06, 95% confidence interval 0.91-1.25). Furthermore, publication bias that inflated type 2 diabetes mellitus risk was statistically detected by Egger's test (P = 0.09). Unstable bodyweight might be modestly associated with the elevated risk of type 2 diabetes mellitus; although serious biases, such as diagnostic suspicion bias and publication bias, made it difficult to assess this association. © 2017 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.

  16. Endotracheal Intubation in Patients with Unstable Cervical Spine Using LMA-Fastrach and Gum Elastic Bogie

    Khan, M. U.

    2014-01-01

    Objective: To evaluate the success of alternative technique of ET- intubation in patients with unstable cervical spine with Philadelphia collar around the neck. Study Design: Case series. Place and Duration of Study: The Department of Anaesthesia, College of Medicine, King Saud University, Riyadh, Saudi Arabia, from June 2009 to June 2012. Methodology: Adult patients of either gender with unstable cervical spine wearing Philadelphia collar electively scheduled for cervical spine decompression and fixation more than one level were included. Those with anticipated difficult intubation, mouth opening 27 kg/m2 were excluded. After induction of anaesthesia FT-LMA was inserted. Correct position of FT-LMA was confirmed then soft straight end of gum elastic bogie was passed through FTLMA into trachea. FT-ILMA was removed on bogie. Reinforced silicon ET- tube was rail road on bogie. The bogie was pulled out and position of ET- tube was confirmed with ETCO2, chest movement and auscultation on bag ventilation. The ease of insertion of FT-LMA, ET- intubation and maximum time taken for successful intubation was noted. Results: 26 patients were studied with mean age of 59.3 A +- 2.93 years and M: F ratio of 7:3. The mean time taken from the insertion of gum elastic bogie to the ET intubation was 38.9 A +- 1.20 seconds. The success rate of ET- intubation in the first attempt was 88.4% and 7.6% in two attempts. Intubation failed in one patient. The mean ease of insertion of FT-LMA and ET- intubation in all patients was 46.7 A +- 2.59 and 46.5 A +- 2.66 respectively on VAS ( 0-100). No complication was noted in any patient. Conclusion: This technique is safe and reliable for achieving adequate ventilation and intubation in patients with unstable cervical spine with Philadelphia collar in place. (author)

  17. Strategies for Proximal Femoral Nailing of Unstable Intertrochanteric Fractures: Lateral Decubitus Position or Traction Table.

    Sonmez, Mesut Mehmet; Camur, Savas; Erturer, Erden; Ugurlar, Meric; Kara, Adnan; Ozturk, Irfan

    2017-03-01

    The aim of this prospective randomized study was to compare the traction table and lateral decubitus position techniques in the management of unstable intertrochanteric fractures. Eighty-two patients with unstable intertrochanteric fractures between 2011 and 2013 were included in this study. All patients were treated surgically with the Proximal Femoral Nail Antirotation implant (DePuy Synthes). Patients were randomized to undergo the procedure in the lateral decubitus position (42 patients) or with the use of a traction table (40 patients). Patients whose procedure was not performed entirely with a semi-invasive method or who required the use of additional fixation materials, such as cables, were excluded from the study. The groups were compared on the basis of the setup time, surgical time, fluoroscopic exposure time, tip-to-apex distance, collodiaphyseal angle, and modified Baumgaertner criteria for radiologic reduction. The setup time, surgical time, and fluoroscopic exposure time were lower and the differences were statistically significant in the lateral decubitus group compared with the traction table group. The collodiaphyseal angles were significantly different between the groups in favor of the lateral decubitus method. The tip-to-apex distance and the classification of reduction according to the modified Baumgaertner criteria did not demonstrate a statistically significant difference between the groups. The lateral decubitus position is used for most open procedures of the hip. We found that this position facilitates exposure for the surgical treatment of unstable intertrochanteric fractures and has advantages over the traction table in terms of set up time, surgical time and fluoroscopic exposure time.

  18. Pre-failure behaviour of an unstable limestone cliff from displacement and seismic data

    J.-L. Got

    2010-04-01

    Full Text Available We monitored the displacement and seismic activity of an unstable vertical rock slice in a natural limestone cliff of the southeast Vercors massif, southeast France, during the months preceding its collapse. Displacement measurements showed an average acceleration of the movement of its top, with clear increases in the displacement velocity and in the discrete seismic event production rate during periods where temperature falls, with more activity when rainfall or frost occurs. Crises of discrete seismic events produce high amplitudes in periodograms, but do not change the high frequency base noise level rate. We infer that these crises express the critical crack growth induced by water weakening (from water vapor condensation or rain of the rock strength rather than to a rapid change in applied stresses. Seismic noise analysis showed a steady increase in the high frequency base noise level and the emergence of spectral modes in the signal recorded by the sensor installed on the unstable rock slice during the weeks preceding the collapse. High frequency seismic noise base level seems to represent subcritical crack growth. It is a smooth and robust parameter whose variations are related to generalized changes in the rupture process. Drop of the seismic noise amplitude was concomitant with the emergence of spectral modes – that are compatible with high-order eigenmodes of the unstable rock slice – during the later stages of its instability. Seismic noise analysis, especially high frequency base noise level analysis may complement that of inverse displacement velocity in early-warning approaches when strong displacement fluctuations occur.

  19. Comparison of occipitocervical and atlantoaxial fusion in treatment of unstable Jefferson fractures

    Yong Hu

    2017-01-01

    Full Text Available Background: Controversy exists regarding the management of unstable Jefferson fractures, with some surgeons performing reduction and immobilization of the patient in a halo vest and others performing open reduction and internal fixation. This study compares the clinical and radiological outcome parameters between posterior atlantoaxial fusion (AAF and occipitocervical fusion (OCF constructs in the treatment of the unstable atlas fracture. Materials and Methods: 68 consecutive patients with unstable Jefferson fractures treated by AAF or OCF between October 2004 and March 2011 were included in this retrospective evaluation from institutional databases. The authors reviewed medical records and original images. The patients were divided into two surgical groups treated with either AAF ( n = 48, F/M 30:18 and OCF ( n = 20, F/M 13:7 fusion. Blood loss, operative time, Japanese Orthopaedic Association (JOA score, visual analog scale (VAS score, atlanto-dens interval, lateral mass displacement, complications, and the bone fusion rates were recorded. Results: Five patients with incomplete paralysis (7.4% demonstrated postoperative improvement by more than 1 grade on the American Spinal Injury Association impairment scale. The JOA score of the AAF group improved from 12.5 ± 3.6 preoperatively to 15.7 ± 2.3 postoperatively, while the JOA score of the OCF group improved from 11.2 ± 3.3 preoperatively to 14.8 ± 4.2 postoperatively. The VAS score of AAF group decreased from 4.8 ± 1.5 preoperatively to 1.0 ± 0.4 postoperatively, the VAS score of the OCF group decreased from 5.4 ± 2.2 preoperatively to 1.3 ± 0.9 postoperatively. Conclusions: The OCF or AAF combined with short-term external immobilization can establish the upper cervical stability and prevent further spinal cord injury and nerve function damage.

  20. Extension of a chaos control method to unstable trajectories on infinite- or finite-time intervals: Experimental verification

    Yagasaki, Kazuyuki

    2007-01-01

    In experiments for single and coupled pendula, we demonstrate the effectiveness of a new control method based on dynamical systems theory for stabilizing unstable aperiodic trajectories defined on infinite- or finite-time intervals. The basic idea of the method is similar to that of the OGY method, which is a well-known, chaos control method. Extended concepts of the stable and unstable manifolds of hyperbolic trajectories are used here