Evaluation of innovative rocket engines for single-stage earth-to-orbit vehicles

NASA Astrophysics Data System (ADS)

Manski, Detlef; Martin, James A.

1988-07-01

Computer models of rocket engines and single-stage-to-orbit vehicles that were developed by the authors at DFVLR and NASA have been combined. The resulting code consists of engine mass, performance, trajectory and vehicle sizing models. The engine mass model includes equations for each subsystem and describes their dependences on various propulsion parameters. The engine performance model consists of multidimensional sets of theoretical propulsion properties and a complete thermodynamic analysis of the engine cycle. The vehicle analyses include an optimized trajectory analysis, mass estimation, and vehicle sizing. A vertical-takeoff, horizontal-landing, single-stage, winged, manned, fully reusable vehicle with a payload capability of 13.6 Mg (30,000 lb) to low earth orbit was selected. Hydrogen, methane, propane, and dual-fuel engines were studied with staged-combustion, gas-generator, dual bell, and the dual-expander cycles. Mixture ratio, chamber pressure, nozzle exit pressure liftoff acceleration, and dual fuel propulsive parameters were optimized.

Evaluation of innovative rocket engines for single-stage earth-to-orbit vehicles

NASA Technical Reports Server (NTRS)

Manski, Detlef; Martin, James A.

1988-01-01

Computer models of rocket engines and single-stage-to-orbit vehicles that were developed by the authors at DFVLR and NASA have been combined. The resulting code consists of engine mass, performance, trajectory and vehicle sizing models. The engine mass model includes equations for each subsystem and describes their dependences on various propulsion parameters. The engine performance model consists of multidimensional sets of theoretical propulsion properties and a complete thermodynamic analysis of the engine cycle. The vehicle analyses include an optimized trajectory analysis, mass estimation, and vehicle sizing. A vertical-takeoff, horizontal-landing, single-stage, winged, manned, fully reusable vehicle with a payload capability of 13.6 Mg (30,000 lb) to low earth orbit was selected. Hydrogen, methane, propane, and dual-fuel engines were studied with staged-combustion, gas-generator, dual bell, and the dual-expander cycles. Mixture ratio, chamber pressure, nozzle exit pressure liftoff acceleration, and dual fuel propulsive parameters were optimized.

Comparison of CFD-calculations of centrifugal compressor stages by NUMECA Fine Turbo and ANSYS CFX programs

NASA Astrophysics Data System (ADS)

Galerkin, Y. B.; Voinov, I. B.; Drozdov, A. A.

2017-08-01

Computational Fluid Dynamics (CFD) methods are widely used for centrifugal compressors design and flow analysis. The calculation results are dependent on the chosen software, turbulence models and solver settings. Two of the most widely applicable programs are NUMECA Fine Turbo and ANSYS CFX. The objects of the study were two different stages. CFD-calculations were made for a single blade channel and for full 360-degree flow paths. Stage 1 with 3D impeller and vaneless diffuser was tested experimentally. Its flow coefficient is 0.08 and loading factor is 0.74. For stage 1 calculations were performed with different grid quality, a different number of cells and different models of turbulence. The best results have demonstrated the Spalart-Allmaras model and mesh with 1.854 million cells. Stage 2 with return channel, vaneless diffuser and 3D impeller with flow coefficient 0.15 and loading factor 0.5 was designed by the known Universal Modeling Method. Its performances were calculated by the well identified Math model. Stage 2 performances by CFD calculations shift to higher flow rate in comparison with design performances. The same result was obtained for stage 1 in comparison with measured performances. Calculated loading factor is higher in both cases for a single blade channel. Loading factor performance calculated for full flow path (“360 degrees”) by ANSYS CFX is in satisfactory agreement with the stage 2 design performance. Maximum efficiency is predicted accurately by the ANSYS CFX “360 degrees” calculation. “Sector” calculation is less accurate. Further research is needed to solve the problem of performances mismatch.

SINGLE-STAGE SPACESHIPS SHOULD BE OUR GOAL

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

Hunter, M.W. Jr.

1963-02-01

The ultimate vehicle for manned space travel within the solar system was considered to be the high-performance single-stage spaceship---a vehicle that could travel from earth to points in space and back time after time. If the performance of single-stage rockets can be made high enough, one can begin to think of reusing equipment exactly as in transport airplane practice. The prospects for a practical gaseous fission rocket have brightened with the recent invention of a new family of systems that operates on a basically different principle. The propellant is heated by radiation from the fission plasma, rather than by directmore » intermixing. Several such systems were suggested. Safety factors were considered to make operation of a spaceship propelled by a gaseous-fission engine safe. (C.E.S.)« less

Maximizing the performance of a multiple-stage variable-throat venturi scrubber for particle collection

NASA Astrophysics Data System (ADS)

Muir, D. M.; Akeredolu, F.

The high collection efficiencies that are required nowadays to meet the stricter pollution control standards necessitate the use of high-energy scrubbers, such as the venturi scrubber, for the arrestment of fine particulate matter from exhaust gas streams. To achieve more energy-efficient particle collection, several venturi stages may be used in series. This paper is principally a theoretical investigation of the performance of a multiple-stage venturi scrubber, the main objective of the study being to establish the best venturi design configuration for any given set of operating conditions. A mathematical model is used to predict collection efficiency vs pressure drop relationships for particle sizes in the range 0.2-5.0 μm for one-, two-, three- and four-stage scrubbers. The theoretical predictions are borne out qualitatively by experimental work. The paper shows that the three-stage venturi produces the highest collection efficiencies over the normal operating range except for the collection of very fine particles at low pressure drops, when the single-stage venturi is best. The significant improvement in performance achieved by the three-stage venturi when compared with conventional single-stage operation increases as both the particle size and system pressure drop increase.

Is Single-stage Revision Safe Following Infected Total Knee Arthroplasty? A Critical Review.

PubMed

Vaishya, Raju; Agarwal, Amit Kumar; Rawat, Sudheer K; Singh, Harsh; Vijay, Vipul

2017-08-30

With the improvement in outcomes and modern prosthesis design, total knee arthroplasty (TKA) has now become a commonly performed surgery. It is postulated that a total of 2-5% of the primary and revision TKA becomes infected every year, requiring a revision procedure which to date is the conventional two-stage revision. The diagnosis and treatment of these periprosthetic infections is a major and challenging task, as it requires precise identification of the pathogen, meticulous debridement, and postoperative rehabilitation. To date, there have been very few studies in existing literature comparing the outcomes of single-stage versus two-stage procedure in infected TKA. The aim of the review was to provide the clinicians an insight into the outcome of the single-stage procedure compared to two-stage procedures and to suggest ways to improve the results further. In the following critical review, a total of 669 cases that underwent either a single or two-stage revision for infected TKA were studied. The postoperative functional scores were comparable in most studies during the early postoperative period. Our data supports the use of a single-stage revision surgery in infected TKA as an alternative to a conventional two-stage procedure. However, larger prospective and multicentric trials are required to validate our findings.

Two-Stage Centrifugal Fan

NASA Technical Reports Server (NTRS)

Converse, David

2011-01-01

Fan designs are often constrained by envelope, rotational speed, weight, and power. Aerodynamic performance and motor electrical performance are heavily influenced by rotational speed. The fan used in this work is at a practical limit for rotational speed due to motor performance characteristics, and there is no more space available in the packaging for a larger fan. The pressure rise requirements keep growing. The way to ordinarily accommodate a higher DP is to spin faster or grow the fan rotor diameter. The invention is to put two radially oriented stages on a single disk. Flow enters the first stage from the center; energy is imparted to the flow in the first stage blades, the flow is redirected some amount opposite to the direction of rotation in the fixed stators, and more energy is imparted to the flow in the second- stage blades. Without increasing either rotational speed or disk diameter, it is believed that as much as 50 percent more DP can be achieved with this design than with an ordinary, single-stage centrifugal design. This invention is useful primarily for fans having relatively low flow rates with relatively high pressure rise requirements.

Space Launch System Mission Flexibility Assessment

NASA Technical Reports Server (NTRS)

Monk, Timothy; Holladay, Jon; Sanders, Terry; Hampton, Bryan

2012-01-01

The Space Launch System (SLS) is envisioned as a heavy lift vehicle that will provide the foundation for future beyond low Earth orbit (LEO) missions. While multiple assessments have been performed to determine the optimal configuration for the SLS, this effort was undertaken to evaluate the flexibility of various concepts for the range of missions that may be required of this system. These mission scenarios include single launch crew and/or cargo delivery to LEO, single launch cargo delivery missions to LEO in support of multi-launch mission campaigns, and single launch beyond LEO missions. Specifically, we assessed options for the single launch beyond LEO mission scenario using a variety of in-space stages and vehicle staging criteria. This was performed to determine the most flexible (and perhaps optimal) method of designing this particular type of mission. A specific mission opportunity to the Jovian system was further assessed to determine potential solutions that may meet currently envisioned mission objectives. This application sought to significantly reduce mission cost by allowing for a direct, faster transfer from Earth to Jupiter and to determine the order-of-magnitude mass margin that would be made available from utilization of the SLS. In general, smaller, existing stages provided comparable performance to larger, new stage developments when the mission scenario allowed for optimal LEO dropoff orbits (e.g. highly elliptical staging orbits). Initial results using this method with early SLS configurations and existing Upper Stages showed the potential of capturing Lunar flyby missions as well as providing significant mass delivery to a Jupiter transfer orbit.

A dual-stage sodium thermal electrochemical converter (Na-TEC)

NASA Astrophysics Data System (ADS)

Limia, Alexander; Ha, Jong Min; Kottke, Peter; Gunawan, Andrey; Fedorov, Andrei G.; Lee, Seung Woo; Yee, Shannon K.

2017-12-01

The sodium thermal electrochemical converter (Na-TEC) is a heat engine that generates electricity through the isothermal expansion of sodium ions. The Na-TEC is a closed system that can theoretically achieve conversion efficiencies above 45% when operating between thermal reservoirs at 1150 K and 550 K. However, thermal designs have confined previous single-stage devices to thermal efficiencies below 20%. To mitigate some of these limitations, we consider dividing the isothermal expansion into two stages; one at the evaporator temperature (1150 K) and another at an intermediate temperature (650 K-1050 K). This dual-stage Na-TEC takes advantage of regeneration and reheating, and could be amenable to better thermal management. Herein, we demonstrate how the dual-stage device can improve the efficiency by up to 8% points over the best performing single-stage device. We also establish an application regime map for the single- and dual-stage Na-TEC in terms of the power density and the total thermal parasitic loss. Generally, a single-stage Na-TEC should be used for applications requiring high power densities, whereas a dual-stage Na-TEC should be used for applications requiring high efficiency.

Control of DC gas flow in a single-stage double-inlet pulse tube cooler

NASA Astrophysics Data System (ADS)

Wang, C.; Thummes, G.; Heiden, C.

The use of double-inlet mode in the pulse tube cooler opens up a possibility of DC gas flow circulating around the regenerator and pulse tube. Numerical analysis shows that effects of DC flow in a single-stage pulse tube cooler are different in some aspects from that in a 4 K pulse tube cooler. For highest cooler efficiency, DC flow should be compensated to a small value, i.e. DC flow over average AC flow at regenerator inlet should be in the range -0.0013 to +0.00016. Dual valves with reversed asymmetric geometries were used for the double-inlet bypass to control the DC flow in this paper. The experiment, performed in a single-stage double-inlet pulse tube cooler, verified that the cooler performance can be significantly improved by precisely controlling the DC flow.

Single shaft automotive gas turbine engine characterization test

NASA Technical Reports Server (NTRS)

Johnson, R. A.

1979-01-01

An automotive gas turbine incorporating a single stage centrifugal compressor and a single stage radial inflow turbine is described. Among the engine's features is the use of wide range variable geometry at the inlet guide vanes, the compressor diffuser vanes, and the turbine inlet vanes to achieve improved part load fuel economy. The engine was tested to determine its performance in both the variable geometry and equivalent fixed geometry modes. Testing was conducted without the originally designed recuperator. Test results were compared with the predicted performance of the nonrecuperative engine based on existing component rig test maps. Agreement between test results and the computer model was achieved.

18.6 K single-stage high frequency multi-bypass coaxial pulse tube cryocooler

NASA Astrophysics Data System (ADS)

Chen, Liubiao; Jin, Hai; Wang, Junjie; Zhou, Yuan; Zhu, Wenxiu; Zhou, Qiang

2013-02-01

A single-stage high frequency multi-bypass coaxial pulse tube cryocooler (PTC) has been developed for physical experiments. The performance characteristics are presented. At present, the cooler has reached the lowest temperature of 18.6 K with an electric input power of 268 W, which is the reported lowest temperature for single-stage high frequency PTC. The cooler typically provides 0.2 W at 20.6 K and 0.5 W at 24.1 K with the input power of 260 W at 300 K ambient temperature. The cooperation phase adjustment method of multi-bypass and double-inlet shows its advantages in experiments, they might be the best way to get temperature below 20 K for single-stage high frequency PTC. The temperature stability of the developed PTC is also observed.

Effect of rotor design tip seed on aerodynamic performance of a model VTOL lift fan under static and crossflow conditions

NASA Technical Reports Server (NTRS)

Stockman, N. O.; Loeffler, I. J.; Lieblein, S.

1973-01-01

Results are presented for a wind tunnel investigation of three single VTOL lift fan stages designed for the same overall total pressure ratio at different rotor tip speeds. The stages were tested in a model lift fan installed in a wing pod. The three stages had essentially the same aerodynamic performance along the operating line. However, differences in stage thrust characteristics were obtained when a variation in back pressure was imposed on the stages by cross-flow effects and thrust-vectoring louvers.

Titanium nitride formation by a dual-stage femtosecond laser process

NASA Astrophysics Data System (ADS)

Hammouti, S.; Holybee, B.; Zhu, W.; Allain, J. P.; Jurczyk, B.; Ruzic, D. N.

2018-06-01

Formation of TiN by femtosecond laser processing in controlled gas atmosphere is reported. A dual-stage process was designed and aimed to first remove and restructure the native oxide layer of titanium surface through laser irradiation under an argon-controlled atmosphere, and then to maximize titanium nitride formation through an irradiation under a nitrogen reactive environment. An extensive XPS study was performed to identify and quantify laser-induced titanium surface chemistry modifications after a single-stage laser process (Ar and N2 individually), and a dual-stage laser process. The importance of each step that composes the dual-stage laser process was demonstrated and leads to the dual-stage laser process for the formation of TiO, Ti2O3 and TiN. In this study, the largest nitride formation occurs for the dual stage process with laser conditions at 4 W/1.3 J cm-2 under argon and 5 W/1.6 J cm-2 under nitrogen, yielding a total TiN composition of 8.9%. Characterization of both single-stage and dual-stage laser process-induced surface morphologies has been performed as well, leading to the observation of a wide range of hierarchical surface structures such as high-frequency ripples, grooves, protuberances and pillow-like patterns. Finally, water wettability was assessed by means of contact angle measurements on untreated titanium surface, and titanium surfaces resulting from either single-stage laser process or dual-stage laser process. Dual-stage laser process allows a transition of titanium surface, from phobic (93°) to philic (35°), making accessible both hydrophilic and chemically functionalized hierarchical surfaces.

Genomic Prediction of Single Crosses in the Early Stages of a Maize Hybrid Breeding Pipeline.

PubMed

Kadam, Dnyaneshwar C; Potts, Sarah M; Bohn, Martin O; Lipka, Alexander E; Lorenz, Aaron J

2016-09-19

Prediction of single-cross performance has been a major goal of plant breeders since the beginning of hybrid breeding. Recently, genomic prediction has shown to be a promising approach, but only limited studies have examined the accuracy of predicting single-cross performance. Moreover, no studies have examined the potential of predicting single crosses among random inbreds derived from a series of biparental families, which resembles the structure of germplasm comprising the initial stages of a hybrid maize breeding pipeline. The main objectives of this study were to evaluate the potential of genomic prediction for identifying superior single crosses early in the hybrid breeding pipeline and optimize its application. To accomplish these objectives, we designed and analyzed a novel population of single crosses representing the Iowa Stiff Stalk Synthetic/Non-Stiff Stalk heterotic pattern commonly used in the development of North American commercial maize hybrids. The performance of single crosses was predicted using parental combining ability and covariance among single crosses. Prediction accuracies were estimated using cross-validation and ranged from 0.28 to 0.77 for grain yield, 0.53 to 0.91 for plant height, and 0.49 to 0.94 for staygreen, depending on the number of tested parents of the single cross and genomic prediction method used. The genomic estimated general and specific combining abilities showed an advantage over genomic covariances among single crosses when one or both parents of the single cross were untested. Overall, our results suggest that genomic prediction of single crosses in the early stages of a hybrid breeding pipeline holds great potential to re-design hybrid breeding and increase its efficiency. Copyright © 2016 Author et al.

160 W 800 fs Yb:YAG single crystal fiber amplifier without CPA.

PubMed

Markovic, Vesna; Rohrbacher, Andreas; Hofmann, Peter; Pallmann, Wolfgang; Pierrot, Simonette; Resan, Bojan

2015-10-05

We demonstrate a compact and simple two-stage Yb:YAG single crystal fiber amplifier which delivers 160 W average power, 800 fs pulses without chirped pulse amplification. This is the highest average power of femtosecond laser based on SCF. Additionally, we demonstrate the highest small signal gain of 32.5 dB from the SCF in the first stage and the highest extraction efficiency of 42% in the second stage. The excellent performance of the second stage was obtained using the bidirectional pumping scheme, which is applied to SCF for the first time.

Two-step single slope/SAR ADC with error correction for CMOS image sensor.

PubMed

Tang, Fang; Bermak, Amine; Amira, Abbes; Amor Benammar, Mohieddine; He, Debiao; Zhao, Xiaojin

2014-01-01

Conventional two-step ADC for CMOS image sensor requires full resolution noise performance in the first stage single slope ADC, leading to high power consumption and large chip area. This paper presents an 11-bit two-step single slope/successive approximation register (SAR) ADC scheme for CMOS image sensor applications. The first stage single slope ADC generates a 3-bit data and 1 redundant bit. The redundant bit is combined with the following 8-bit SAR ADC output code using a proposed error correction algorithm. Instead of requiring full resolution noise performance, the first stage single slope circuit of the proposed ADC can tolerate up to 3.125% quantization noise. With the proposed error correction mechanism, the power consumption and chip area of the single slope ADC are significantly reduced. The prototype ADC is fabricated using 0.18 μ m CMOS technology. The chip area of the proposed ADC is 7 μ m × 500 μ m. The measurement results show that the energy efficiency figure-of-merit (FOM) of the proposed ADC core is only 125 pJ/sample under 1.4 V power supply and the chip area efficiency is 84 k  μ m(2) · cycles/sample.

Temperature-phased anaerobic digestion of food waste: A comparison with single-stage digestions based on performance and energy balance.

PubMed

Xiao, Benyi; Qin, Yu; Zhang, Wenzhe; Wu, Jing; Qiang, Hong; Liu, Junxin; Li, Yu-You

2018-02-01

The temperature-phased anaerobic digestion (TPAD) of food waste was studied for the purpose of comparing with single-stage mesophilic and thermophilic anaerobic digestion. The biogas and methane yields in the TPAD during the steady period were 0.759 ± 0.115 L/g added VS and 0.454 ± 0.201 L/g added VS, which were lower than those in the two single-stage anaerobic digestion. The improper sludge retention time may be the reason for the lower biogas and methane production in TPAD. The removal of volatile solids in the TPAD was 78.55 ± 4.59% and the lowest among the three anaerobic digestion processes. The reaction ratios of the four anaerobic digestion steps in the TPAD were all lower than those in the two single-stage anaerobic digestion. The energy conversion efficiency of the degraded substrate in the TPAD was similar with those in single-stage mesophilic and thermophilic anaerobic digestion systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparative assessment of single-stage and two-stage anaerobic digestion for the treatment of thin stillage.

PubMed

Nasr, Noha; Elbeshbishy, Elsayed; Hafez, Hisham; Nakhla, George; El Naggar, M Hesham

2012-05-01

A comparative evaluation of single-stage and two-stage anaerobic digestion processes for biomethane and biohydrogen production using thin stillage was performed to assess the impact of separating the acidogenic and methanogenic stages on anaerobic digestion. Thin stillage, the main by-product from ethanol production, was characterized by high total chemical oxygen demand (TCOD) of 122 g/L and total volatile fatty acids (TVFAs) of 12 g/L. A maximum methane yield of 0.33 L CH(4)/gCOD(added) (STP) was achieved in the two-stage process while a single-stage process achieved a maximum yield of only 0.26 L CH(4)/gCOD(added) (STP). The separation of acidification stage increased the TVFAs to TCOD ratio from 10% in the raw thin stillage to 54% due to the conversion of carbohydrates into hydrogen and VFAs. Comparison of the two processes based on energy outcome revealed that an increase of 18.5% in the total energy yield was achieved using two-stage anaerobic digestion. Copyright © 2012 Elsevier Ltd. All rights reserved.

Single-stage experimental evaluation of tandem-airfoil rotor stator blading for compressors. Part 6: Data and performance for stage D

NASA Technical Reports Server (NTRS)

Clemmons, D. R.

1973-01-01

An axial flow compressor stage, having single-airfoil blading, was designed for zero rotor prewhirl, constant rotor work across the span, and axial discharge flow. The stage was designed to produce a pressure ratio of 1.265 at a rotor tip velocity of 757 ft/sec. The rotor had an inlet hub/tip ratio of 0.8. The design procedure accounted for the rotor inlet boundary layer and included the effects of axial velocity ratio and secondary flow on blade row performance. The objectives of this experimental program were: (1) to obtain performance with uniform and distorted inlet flow for comparison with the performance of a stage consisting of tandem-airfoil blading designed for the same vector diagrams; and (2) to evaluate the effectiveness of accounting for the inlet boundary layer, axial velocity ratio, and secondary flows in the stage design. With uniform inlet flow, the rotor achieved a maximum adiabatic efficiency of 90.1% at design equivalent rotor speed and a pressure ratio of 1.281. The stage maximum adiabatic efficiency at design equivalent rotor speed with uniform inlet flow was 86.1% at a pressure ratio of 1.266. Hub radial, tip radial, and circumferential distortion of the inlet flow caused reductions in surge pressure ratio of approximately 2, 10 and 5%, respectively, at design rotor speed.

Single-stage laparoscopic common bile duct exploration and cholecystectomy versus two-stage endoscopic stone extraction followed by laparoscopic cholecystectomy for patients with concomitant gallbladder stones and common bile duct stones: a randomized controlled trial.

PubMed

Bansal, Virinder Kumar; Misra, Mahesh C; Rajan, Karthik; Kilambi, Ragini; Kumar, Subodh; Krishna, Asuri; Kumar, Atin; Pandav, Chandrakant S; Subramaniam, Rajeshwari; Arora, M K; Garg, Pramod Kumar

2014-03-01

The ideal method for managing concomitant gallbladder stones and common bile duct (CBD) stones is debatable. The currently preferred method is two-stage endoscopic stone extraction followed by laparoscopic cholecystectomy (LC). This prospective randomized trial compared the success and cost effectiveness of single- and two-stage management of patients with concomitant gallbladder and CBD stones. Consecutive patients with concomitant gallbladder and CBD stones were randomized to either single-stage laparoscopic CBD exploration and cholecystectomy (group 1) or endoscopic retrograde cholangiopancreatography (ERCP) for endoscopic extraction of CBD stones followed by LC (group 2). Success was defined as complete clearance of CBD and cholecystectomy by the intended method. Cost effectiveness was measured using the incremental cost-effectiveness ratio. Intention-to-treat analysis was performed to compare outcomes. From February 2009 to October 2012, 168 patients were randomized: 84 to the single-stage procedure (group 1) and 84 to the two-stage procedure (group 2). Both groups were matched with regard to demographic and clinical parameters. The success rates of laparoscopic CBD exploration and ERCP for clearance of CBD were similar (91.7 vs. 88.1 %). The overall success rate also was comparable: 88.1 % in group 1 and 79.8 % in group 2 (p = 0.20). Direct choledochotomy was performed in 83 of the 84 patients. The mean operative time was significantly longer in group 1 (135.7 ± 36.6 vs. 72.4 ± 27.6 min; p ≤ 0.001), but the overall hospital stay was significantly shorter (4.6 ± 2.4 vs. 5.3 ± 6.2 days; p = 0.03). Group 2 had a significantly greater number of procedures per patient (p < 0.001) and a higher cost (p = 0.002). The two groups did not differ significantly in terms of postoperative wound infection rates or major complications. Single- and two-stage management for uncomplicated concomitant gallbladder and CBD stones had similar success and complication rates, but the single-stage strategy was better in terms of shorter hospital stay, need for fewer procedures, and cost effectiveness.

Effect of Blade-surface Finish on Performance of a Single-stage Axial-flow Compressor

NASA Technical Reports Server (NTRS)

Moses, Jason J; Serovy, George, K

1951-01-01

A set of modified NACA 5509-34 rotor and stator blades was investigated with rough-machine, hand-filed, and highly polished surface finishes over a range of weight flows at six equivalent tip speeds from 672 to 1092 feet per second to determine the effect of blade-surface finish on the performance of a single-stage axial-flow compressor. Surface-finish effects decreased with increasing compressor speed and with decreasing flow at a given speed. In general, finishing blade surfaces below the roughness that may be considered aerodynamically smooth on the basis of an admissible-roughness formula will have no effect on compressor performance.

Recording single neurons' action potentials from freely moving pigeons across three stages of learning.

PubMed

Starosta, Sarah; Stüttgen, Maik C; Güntürkün, Onur

2014-06-02

While the subject of learning has attracted immense interest from both behavioral and neural scientists, only relatively few investigators have observed single-neuron activity while animals are acquiring an operantly conditioned response, or when that response is extinguished. But even in these cases, observation periods usually encompass only a single stage of learning, i.e. acquisition or extinction, but not both (exceptions include protocols employing reversal learning; see Bingman et al.(1) for an example). However, acquisition and extinction entail different learning mechanisms and are therefore expected to be accompanied by different types and/or loci of neural plasticity. Accordingly, we developed a behavioral paradigm which institutes three stages of learning in a single behavioral session and which is well suited for the simultaneous recording of single neurons' action potentials. Animals are trained on a single-interval forced choice task which requires mapping each of two possible choice responses to the presentation of different novel visual stimuli (acquisition). After having reached a predefined performance criterion, one of the two choice responses is no longer reinforced (extinction). Following a certain decrement in performance level, correct responses are reinforced again (reacquisition). By using a new set of stimuli in every session, animals can undergo the acquisition-extinction-reacquisition process repeatedly. Because all three stages of learning occur in a single behavioral session, the paradigm is ideal for the simultaneous observation of the spiking output of multiple single neurons. We use pigeons as model systems, but the task can easily be adapted to any other species capable of conditioned discrimination learning.

Core compressor exit stage study. Volume 4: Data and performance report for the best stage configuration

NASA Technical Reports Server (NTRS)

Wisler, D. C.

1981-01-01

The core compressor exit stage study program develops rear stage blading designs that have lower losses in their endwall boundary layer regions. The test data and performance results for the best stage configuration consisting of Rotor-B running with Stator-B are described. The technical approach in this efficiency improvement program utilizes a low speed research compressor. Tests were conducted in two ways: (1) to use four identical stages of blading to obtain test data in a true multistage environment and (2) to use a single stage of blading to compare with the multistage test results. The effects of increased rotor tip clearances and circumferential groove casing treatment are evaluated.

Plasma gasification of refuse derived fuel in a single-stage system using different gasifying agents.

PubMed

Agon, N; Hrabovský, M; Chumak, O; Hlína, M; Kopecký, V; Masláni, A; Bosmans, A; Helsen, L; Skoblja, S; Van Oost, G; Vierendeels, J

2016-01-01

The renewable evolution in the energy industry and the depletion of natural resources are putting pressure on the waste industry to shift towards flexible treatment technologies with efficient materials and/or energy recovery. In this context, a thermochemical conversion method of recent interest is plasma gasification, which is capable of producing syngas from a wide variety of waste streams. The produced syngas can be valorized for both energetic (heat and/or electricity) and chemical (ammonia, hydrogen or liquid hydrocarbons) end-purposes. This paper evaluates the performance of experiments on a single-stage plasma gasification system for the treatment of refuse-derived fuel (RDF) from excavated waste. A comparative analysis of the syngas characteristics and process yields was done for seven cases with different types of gasifying agents (CO2+O2, H2O, CO2+H2O and O2+H2O). The syngas compositions were compared to the thermodynamic equilibrium compositions and the performance of the single-stage plasma gasification of RDF was compared to that of similar experiments with biomass and to the performance of a two-stage plasma gasification process with RDF. The temperature range of the experiment was from 1400 to 1600 K and for all cases, a medium calorific value syngas was produced with lower heating values up to 10.9 MJ/Nm(3), low levels of tar, high levels of CO and H2 and which composition was in good agreement to the equilibrium composition. The carbon conversion efficiency ranged from 80% to 100% and maximum cold gas efficiency and mechanical gasification efficiency of respectively 56% and 95%, were registered. Overall, the treatment of RDF proved to be less performant than that of biomass in the same system. Compared to a two-stage plasma gasification system, the produced syngas from the single-stage reactor showed more favourable characteristics, while the recovery of the solid residue as a vitrified slag is an advantage of the two-stage set-up. Copyright © 2015 Elsevier Ltd. All rights reserved.

Laparoscopic sleeve gastrectomy as revisional surgery for adjustable gastric band erosion.

PubMed

Park, Yeon Ho; Kim, Seong Min

2014-09-01

Laparoscopic sleeve gastrectomy (LSG) has been increasingly adopted as a revisional surgery for failed gastric banding. However, little information is available regarding the outcome of revisional LSG for band erosion. A retrospective database analysis was performed to study LSG as revisional surgery for band erosion. For staged revision, we waited a minimum of 3 months after band removal, and for single-stage revision, the band was removed by gastrotomy, and sleeve gastrectomy was performed at the same time. Main outcome measures were success rates of therapeutic strategies, morbidity, and mortality rates, length of stay, and body mass index (BMI) (percentage excess weight loss [%EWL]) before and after revision. From March 2011 to February 2013, 9 female patients underwent revisional LSG. Average age was 34.7 years. Six patients underwent a staged procedure, and the other 3 underwent a single-stage revision. Among the 6 staged patients, eroded bands had been removed by laparoscopy in 4 and by endoscopy in 2 without complications. Their LSGs were performed at a median of 4.4 months after band removal. Another 2 patients underwent single-stage revision. In the last patient, band erosion was incidentally found during a revisional LSG for insufficient weight loss. No mortality occurred. There were one stenosis and two proximal leaks. Two patients with leak underwent total gastrectomy and fistulojejunostomy. After a mean follow-up of 19.1 months, all 9 patients exhibited weight loss. The mean (±standard deviation [SD]) pre- and post-LSG BMIs were 34.0±4.4 and 25.6±2.1 kg/m(2), respectively, and their mean (±SD) %EWL from prebanding was 86.8±10.1%. Revisional LSG resulted in a further median %EWL of 28.0% (range, 7.9%-68.9%) versus weight at time of band removal. Revisional LSG after band erosion was found to be feasible and effective. However, it is prone to severe complication. In selected cases of band erosion, LSG can be performed at the time of band removal in a single stage.

Performance evaluation of a piezoactuator-based single-stage valve system subjected to high temperature

NASA Astrophysics Data System (ADS)

Jeon, Juncheol; Han, Chulhee; Chung, Jye Ung; Choi, Seung-Bok

2015-01-01

In this paper, a novel single-stage valve system activated by a piezostack actuator is proposed and experimentally evaluated at both room temperature (20 °C) and high temperature (100 °C) conditions. A hinge-lever displacement amplifier is adopted in the valve system to magnify the displacement generated from the piezostack actuator. After explaining the operating principle of the proposed piezostack-driven single-stage valve system, the geometric dimensions and mechanical properties of the valve components are discussed in details. An experimental apparatus is then manufactured to evaluate the performances of the valve system such as flow rate. The experimental apparatus consists of a heat chamber, which can regulate the temperature of the valve system and oil, pneumatic-hydraulic cylinders, a hydraulic circuit, a pneumatic circuit, electronic devices, an interface card, and a high voltage amplifier. The pneumatic-hydraulic cylinder transforms the pneumatic pressure into hydraulic pressure. The performances of the valve system regarding spool response, pressure drop, and flow rate are evaluated and presented. In addition, the performance of the valve system under high temperature condition is compared with that under room temperature condition. The experimental results are plotted in both frequency and time domains.

Performance of single-stage axial-flow transonic compressor with rotor and stator aspect ratios of 1.19 and 1.26 respectively, and with design pressure ratio of 2.05

NASA Technical Reports Server (NTRS)

Moore, R. D.; Reid, L.

1980-01-01

The overall and blade-element performances of a low-aspect-ratio transonic compressor stage are presented over the stable operating flow range for speeds from 50 to 100 percent of design. At design speed the rotor and stage achieved peak efficiencies of 0.876 and 0.840 at pressure ratios of 2.056 and 2.000, respectively. The stage stall margin at design speed was 10 percent.

Single stage to orbit vertical takeoff and landing concept technology challenges

NASA Astrophysics Data System (ADS)

Heald, Daniel A.; Kessler, Thomas L.

1991-10-01

General Dynamics has developed a VTOL concept for a single-stage-to-orbit under contract to the Strategic Defense Initiative Organization. This paper briefly describes the configuration and its basic operations. Two key advanced technolgy areas are then discussed: high-performance rocket propulsion employing a plug nozzle arrangement and integrated health management to facilitate very rapid turnaround between flights, more like an aircraft than today's rockets.

Performance characteristics of an excimer laser (XeCl) with single-stage magnetic pulse compression

NASA Astrophysics Data System (ADS)

Varshnay, N. K.; Singh, A.; Benerji, N. S.

2017-02-01

Performance characteristics of an excimer laser (XeCl) with single-stage magnetic pulse compression suitable for material processing applications are presented here. The laser incorporates in-built compact gas circulation and gas cooling to ensure fresh gas mixture between the electrodes for repetitive operation. A magnetically coupled tangential blower is used for gas circulation inside the laser chamber for repetitive operation. The exciter consists of C-C energy transfer circuit and thyratron is used as a high-voltage main switch with single-stage magnetic pulse compression (MPC) between thyratron and the laser electrodes. Low inductance of the laser head and uniform and intense pre-ionization are the main features of the electric circuit used in the laser. A 250 ns rise time voltage pulse was compressed to 100 ns duration with a single-stage magnetic pulse compressor using Ni-Zn ferrite cores. The laser can generate about 150 mJ at ˜100 Hz rep-rate reliably from a discharge volume of 100 cm 3. 2D spatial laser beam profile generated is presented here. The profile shows that the laser beam is completely filled with flat-top which is suitable for material processing applications. The SEM image of the microhole generated on copper target is presented here.

Effects of Compression, Staging, and Braid Angle on Braided Rope Seal Performance

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Adams, Michael L.

1997-01-01

Future turbine engines and industrial systems will be operating at increased temperatures to achieve more demanding efficiency and performance goals. In the highest temperature sections of the engine new material systems such as ceramics and intermetallics are being considered to withstand the harsh thermal environment. Components constructed of these low expansion-rate materials experience thermal strains and a resulting reduction of life when rigidly attached to high expansion-rate, superalloy support structures. Seals are being designed to both seal and to serve as compliant mounts allowing for relative thermal growths between high temperature but brittle primary structures and the surrounding support structures. Previous seal research yielded several braided rope seal designs which demonstrated the ability to both seal and serve as a compliant mount. The hybrid seal was constructed of an all-ceramic (alumina-silica) core overbraided with a superalloy wire sheath (cobalt based superalloy). The all ceramic seal was constructed of an all-ceramic (alumina-silica) core overbraided with multiple ceramic (alumina-silica) sheath layers. Program goals for braided rope seals are to improve flow resistance and/or seal resilience. To that end, the current report studies the test results of: baseline and modified hybrid seals; two stage hybrid and two stage all-ceramic seal configurations; and single stage hybrid and single stage all-ceramic seal configurations for a range of seal crush conditions. Hybrid seal modifications include increasing the sheath braid angle and core coverage. For the same percent seal cross-sectional crush, results show that increasing the hybrid seal braid angle increased seal stiffness and seal unit load, resulting in flows approximately one third of the baseline hybrid seal flows. For both hybrid and all-ceramic seals, two stage seal configurations significantly outperformed single stage configurations. Two stage seal flows were at least 30% less than the single stage seal flows for the same seal crush. Furthermore, test results of single stage seals indicate that for both all-ceramic and hybrid seals, a specific seal crush condition exists at which minimum flows are achieved (i.e. increasing seal crush beyond a certain point does not result in better flow performance). Flow results are presented for a range of pressures and temperatures from ambient to 1300 F, before and after scrubbing. Compression tests results show that for both all-ceramic and hybrid seals, seal preload and stiffness increase with seal crush, but residual seal interference remains constant.

Rho-Isp Revisited and Basic Stage Mass Estimating for Launch Vehicle Conceptual Sizing Studies

NASA Technical Reports Server (NTRS)

Kibbey, Timothy P.

2015-01-01

The ideal rocket equation is manipulated to demonstrate the essential link between propellant density and specific impulse as the two primary stage performance drivers for a launch vehicle. This is illustrated by examining volume-limited stages such as first stages and boosters. This proves to be a good approximation for first-order or Phase A vehicle design studies for solid rocket motors and for liquid stages, except when comparing to hydrogen-fueled stages. A next-order mass model is developed that is able to model the mass differences between hydrogen-fueled and other stages. Propellants considered range in density from liquid methane to inhibited red fuming nitric acid. Calculated comparisons are shown for solid rocket boosters, liquid first stages, liquid upper stages, and a balloon-deployed single-stage-to-orbit concept. The derived relationships are ripe for inclusion in a multi-stage design space exploration and optimization algorithm, as well as for single-parameter comparisons such as those shown herein.

Investigation of different ethylenediamine-N,N'-disuccinic acid-enhanced washing configurations for remediation of a Cu-contaminated soil: process kinetics and efficiency comparison between single-stage and multi-stage configurations.

PubMed

Ferraro, Alberto; Fabbricino, Massimiliano; van Hullebusch, Eric D; Esposito, Giovanni

2017-09-01

A comparison of Cu extraction yields for three different ethylenediamine-N,N'-disuccinic acid (EDDS)-enhanced washing configurations was performed on a Cu-contaminated soil. Batch experiments were used to simulate a single-stage continuous stirred tank reactor (CSTR) and a multi-stage (side feeding and counter-current) reactor. Single-stage CSTR conditions were simulated for various EDDS:(Cu + Cd + Pb + Co + Ni + Zn) molar ratio (EDDS:M ratio) (from 1 to 30) and liquid to soil (L/S) ratio (from 15 to 45). The highest Cu extraction yield (≃56%) was achieved with EDDS:M = 30. In contrast, a Cu extraction yield decrease was observed with increasing L/S ratio with highest extracted Cu achievement (≃48%) for L/S = 15. Side feeding configuration was tested in four experimental conditions through different fractionation mode of EDDS dose and treatment time at each washing step. Results from the four tests showed all enhanced Cu extraction (maximum values from ≃43 to ≃51%) achieved at lower treatment time and lower EDDS:M molar ratio compared to CSTR configuration with L/S = 25 and EDDS:M = 10. The counter-current washing was carried out through two washing flows achieving a process performance enhancement with 27% increase of extracted Cu compared to single-stage CSTR configuration. Higher Cu extraction percentage (36.8%) was observed in the first washing phase than in the second one (24.7%).

Use of real time gas production data for more accurate comparison of continuous single-stage and two-stage fermentation.

PubMed

Massanet-Nicolau, Jaime; Dinsdale, Richard; Guwy, Alan; Shipley, Gary

2013-02-01

Changes in fermenter gas composition within a given 24h period can cause severe bias in calculations of biogas or energy yields based on just one or two measurements of gas composition per day, as is common in other studies of two-stage fermentation. To overcome this bias, real time recording of gas composition and production were used to undertake a detailed and controlled comparison of single-stage and two-stage fermentation using a real world substrate (wheat feed pellets). When a two-stage fermentation system was used, methane yields increased from 261 L kg(-1)VS using a 20 day HRT, single-stage fermentation, to 359 L kg(-1) VS using a two-stage fermentation with the same overall retention time--an increase of 37%. Additionally a hydrogen yield of 7 L kg(-1) VS was obtained when two-stage fermentation was used. The two-stage system could also be operated at a shorter, 12 day HRT and still produce higher methane yields (306 L kg(-1) VS). Both two-stage fermentation systems evaluated exhibited methane yields in excess of that predicted by a biological methane potential test (BMP) performed using the same feedstock (260 L kg(-1)VS). Copyright © 2012 Elsevier Ltd. All rights reserved.

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 2: Data and performance for stage A

NASA Technical Reports Server (NTRS)

Brent, J. A.

1972-01-01

Stage A, comprised of a conventional rotor and stator, was designed and tested to establish a performance baseline for comparison with the results of subsequent tests planned for two tandem-blade stages. The rotor had an inlet hub/tip ratio of 0.8 and a design tip velocity of 757 ft/sec. At design equivalent rotor speed, rotor A achieved a maximum adiabatic efficiency of 85.1 percent at a pressure ratio of 1.29. The stage maximum adiabatic efficiency was 78.6 percent at a pressure ratio of 1.27.

Expendable solid rocket motor upper stages for the Space Shuttle

NASA Technical Reports Server (NTRS)

Davis, H. P.; Jones, C. M.

1974-01-01

A family of expendable solid rocket motor upper stages has been conceptually defined to provide the payloads for the Space Shuttle with performance capability beyond the low earth operational range of the Shuttle Orbiter. In this concept-feasibility assessment, three new solid rocket motors of fixed impulse are defined for use with payloads requiring levels of higher energy. The conceptual design of these motors is constrained to limit thrusting loads into the payloads and to conserve payload bay length. These motors are combined in various vehicle configurations with stage components derived from other programs for the performance of a broad range of upper-stage missions from spin-stabilized, single-stage transfers to three-axis stabilized, multistage insertions. Estimated payload delivery performance and combined payload mission loading configurations are provided for the upper-stage configurations.

Investigation of Single-Stage Modified Turbine of Mark 25 Torpedo Power Plant

NASA Technical Reports Server (NTRS)

Hoyt, Jack W.

1947-01-01

Efficiency investigations have been made on a single-stage modification of the turbine of a Mark 25 aerial torpedo to determine the performance of the unit with five different turbine nozzles. The output of the turbine blades was computed by analyzing the windage and mechanical-friction losses of the unit. The turbine was faund to be most efficient with a cast nozzle having sharp-edged inlets to the nine nozzle ports. An analysis af the effectiveness af the first and second stages of the standard Mark 25 torpedo turbine indicates that the first- stage turbine contributes nearly all the brake power produced at blade-jet speed ratios above 0.26.

Raytheon's next generation compact inline cryocooler architecture

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

Schaefer, B. R.; Bellis, L.; Ellis, M. J.

2014-01-29

Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determinemore » the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (≤25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing techniques and hardware can be utilized to null all motion along the common axis. Low vibration translates to better sensor performance resulting in simpler, more direct mechanical mounting configurations, eliminating the need for convoluted, expensive, massive, long lead damping hardware.« less

Raytheon's next generation compact inline cryocooler architecture

NASA Astrophysics Data System (ADS)

Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T.

2014-01-01

Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (≤25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing techniques and hardware can be utilized to null all motion along the common axis. Low vibration translates to better sensor performance resulting in simpler, more direct mechanical mounting configurations, eliminating the need for convoluted, expensive, massive, long lead damping hardware.

Nonimaging concentrators for solar thermal energy

NASA Astrophysics Data System (ADS)

Winston, R.; Gallagher, J. J.

1980-03-01

A small experimental solar collector test facility was used to explore applications of nonimaging optics for solar thermal concentration in three substantially different configurations: a single stage system with moderate concentration on an evacuated absorber (a 5.25X evacuated tube Compound Parabolic Concentrator or CPC), a two stage system with high concentration and a non-evacuated absorber (a 16X Fresnel lens/CPC type mirror) and moderate concentration single stage systems with non-evacuated absorbers for lower temperature (a 3X and a 6.5X CPC). Prototypes of each of these systems were designed, built and tested. The performance characteristics are presented.

Single-stage electrohydraulic servosystem for actuating on airflow valve with frequencies to 500 hertz

NASA Technical Reports Server (NTRS)

Webb, J. A., Jr.; Mehmed, O.; Lorenzo, C. F.

1980-01-01

An airflow valve and its electrohydraulic actuation servosystem are described. The servosystem uses a high-power, single-stage servovalve to obtain a dynamic response beyond that of systems designed with conventional two-stage servovalves. The electrohydraulic servosystem is analyzed and the limitations imposed on system performance by such nonlinearities as signal saturations and power limitations are discussed. Descriptions of the mechanical design concepts and developmental considerations are included. Dynamic data, in the form of sweep-frequency test results, are presented and comparison with analytical results obtained with an analog computer model is made.

Total Cavopulmonary Connection for Functionally Single Ventricle without Cardiopulmonary Bypass Support.

PubMed

Bangash, Sohail Khan; Pathan, Iqbal Hussain; Zaki, Saad Bader

2016-10-01

A heart with two atriums but one ventricle, an anatomy with a unique physiology, is responsible for many creative surgical and interventional approaches in history. Different surgical techniques have been used to address this strange physiology of parallel circulation. All these attempts met with failure till the concept of Fontan circulation was described. Currently, controversy exists between multistage vs. single stage total cavopulmonary connections. Total cavopulmonary connection is the only definitive procedure performed to provide palliation for patients with complex congenital heart defects which cannot support a biventricular circulation. We report a case with tricuspid atresia with transposition of great arteries and pulmonary stenosis with persistant left-sided superior vena cava and functionally single ventricle. Patient successfully underwent single stage extra-cardiac total cavopulmonary connection. In this case, bilateral Glenn with extra-cardiac inferior vena cava to main pulmonary artery shunt was performed off-pump.

Standardized Protocol for Virtual Surgical Plan and 3-Dimensional Surgical Template-Assisted Single-Stage Mandible Contour Surgery.

PubMed

Fu, Xi; Qiao, Jia; Girod, Sabine; Niu, Feng; Liu, Jian Feng; Lee, Gordon K; Gui, Lai

2017-09-01

Mandible contour surgery, including reduction gonioplasty and genioplasty, has become increasingly popular in East Asia. However, it is technically challenging and, hence, leads to a long learning curve and high complication rates and often needs secondary revisions. The increasing use of 3-dimensional (3D) technology makes accurate single-stage mandible contour surgery with minimum complication rates possible with a virtual surgical plan (VSP) and 3-D surgical templates. This study is to establish a standardized protocol for VSP and 3-D surgical templates-assisted mandible contour surgery and evaluate the accuracy of the protocol. In this study, we enrolled 20 patients for mandible contour surgery. Our protocol is to perform VSP based on 3-D computed tomography data. Then, design and 3-D print surgical templates based on preoperative VSP. The accuracy of the method was analyzed by 3-D comparison of VSP and postoperative results using detailed computer analysis. All patients had symmetric, natural osteotomy lines and satisfactory facial ratios in a single-stage operation. The average relative error of VSP and postoperative result on the entire skull was 0.41 ± 0.13 mm. The average new left gonial error was 0.43 ± 0.77 mm. The average new right gonial error was 0.45 ± 0.69 mm. The average pognion error was 0.79 ± 1.21 mm. Patients were very satisfied with the aesthetic results. Surgeons were very satisfied with the performance of surgical templates to facilitate the operation. Our standardized protocol of VSP and 3-D printed surgical templates-assisted single-stage mandible contour surgery results in accurate, safe, and predictable outcome in a single stage.

Role of endorectal coil magnetic resonance imaging in treatment of patients with prostate cancer and in determining radical prostatectomy surgical margin status: report of a single surgeon's practice.

PubMed

Zhang, Jian Qing; Loughlin, Kevin R; Zou, Kelly H; Haker, Steven; Tempany, Clare M C

2007-06-01

To evaluate the role of the combination of endorectal coil and external multicoil array magnetic resonance imaging (MRI) in the management of prostate cancer and predicting the surgical margin status in a single-surgeon practice. We reviewed all patients referred by a single surgeon from January 1993 to May 2002 for staging prostate MRI before selecting treatment. All MRI examinations were performed using 1.5T (Signa, GE Medical Systems) with a combination of endorectal and pelvic multicoil array. The tumor size, stage, and total gland volume on MRI, prostate-specific antigen (PSA) level, and Gleason score were all compared with the pathologic stage and diagnosis of positive surgical margins (PSMs). A total of 232 patients were evaluated, of whom 110 underwent radical prostatectomy, all performed by one surgeon (group 1), and 122 did not (group 2). The results showed that MRI stage, PSA level, and age were all significantly different (P <0.001). In group 1, the results showed a high specificity (99%) and accuracy (91%) for MRI staging of T3 cancer. The postoperative follow-up (median 4.5 years) revealed that 90% of men had PSA levels of less than 0.1 ng/mL. The PSM rate was 16%. No significant difference was found on MRI between the PSM group and non-PSM group. A single tumor length greater than 1.8 cm was the cutpoint above which PSMs were found (P = 0.002). The results of our study have shown that the combined use of clinical data and endorectal MRI can help optimize patient treatment and selection for surgery and, in a single surgeon's practice, lead to successful outcomes.

The Role of Endorectal Coil MRI in the management of patients with prostate cancer and in determining radical prostatectomy surgical margin status: A report of a single surgeon's practice

PubMed Central

Zhang, Jianqing; Loughlin, Kevin R.; Zou, Kelly H.; Haker, Steven; Tempany, Clare M.C.

2009-01-01

Objective To evaluate the role of combination of endorectal coil and external multicoil array MRI in the management of prostate cancer and predicting the surgical margin status in a single surgical practice. Materials and Methods We reviewed all patients referred by a single surgeon from January 1993 to May 2002 for staging prostate MRI prior to selecting treatment. All MRI examinations were performed using 1.5T (Signa; GE Medical Systems) with a combination of endorectal and pelvic multi-coil array. The tumor size, stage and total gland volume on MR, PSA and Gleason grade were all compared with the pathological stage and diagnosis of positive surgical margin (PSM). Result A total of 232 patients were evaluated, of which 110 underwent radical prostatectomy all performed by one surgeon (Group 1), and 122 did not (Group 2). The results showed MRI stage, PSA and age, all significantly different (P<0.001). In Group 1, the results showed a high specificity (99%) and accuracy (91%) of the MRI staging T3. Post-surgical follow up (median 4.5 years) showed 90% of men had PSA levels below 0.1ng/ml. The positive surgical margin (PSM) rate was 16%. There was no significant difference found on MR imaging between PSM group and non-PSM group. A single tumor length above 1.8cm was the cut point above which there was PSM (P=0.002). Conclusion In conclusion, the combined use of clinical data and endorectal MR imaging can help optimize patient management and selection for surgery, and in a single surgeon's practice lead to successful outcomes. PMID:17572201

Immediate Implant-based Prepectoral Breast Reconstruction Using a Vertical Incision

PubMed Central

Lind, Jeffrey G.; Hopkins, Elizabeth G.

2015-01-01

Background: Ideally, breast reconstruction is performed at the time of mastectomy in a single stage with minimal scarring. However, postoperative complications with direct-to-implant subpectoral reconstruction remain significant. These include asymmetry, flap necrosis, animation deformity, and discomfort. We report on a series of patients who have undergone immediate single-stage prepectoral, implant-based breast reconstruction with a smooth, adjustable saline implant covered with mesh/acellular dermal matrix for support using a vertical mastectomy incision. This technique, when combined with an adjustable implant, addresses the complications related to subpectoral implant placement of traditional expanders. Our follow-up time, 4.6 years (55 months), shows a low risk of implant loss and elimination of animation deformity while also providing patients with a safe and aesthetically pleasing result. Methods: All patients who underwent immediate implant-based prepectoral breast reconstruction using a vertical mastectomy incision as a single-staged procedure were included. Charts were reviewed retrospectively. Adjustable smooth round saline implants and mesh/acellular dermal matrix were used for fixation in all cases. Results: Thirty-one patients (62 breasts) underwent single-staged implant-based prepectoral breast reconstruction using a vertical mastectomy incision. Postoperative complications occurred in 9 patients, 6 of which were resolved with postoperative intervention while only 2 cases resulted in implant loss. Conclusions: There can be significant morbidity associated with traditional subpectoral implant-based breast reconstruction. As an alternative, the results of this study show that an immediate single-stage prepectoral breast reconstruction with a smooth saline adjustable implant, using a vertical incision, in conjunction with mesh/matrix support can be performed with excellent aesthetic outcomes and minimal complications. PMID:26180713

Design and control of a decoupled two degree of freedom translational parallel micro-positioning stage.

PubMed

Lai, Lei-Jie; Gu, Guo-Ying; Zhu, Li-Min

2012-04-01

This paper presents a novel decoupled two degrees of freedom (2-DOF) translational parallel micro-positioning stage. The stage consists of a monolithic compliant mechanism driven by two piezoelectric actuators. The end-effector of the stage is connected to the base by four independent kinematic limbs. Two types of compound flexure module are serially connected to provide 2-DOF for each limb. The compound flexure modules and mirror symmetric distribution of the four limbs significantly reduce the input and output cross couplings and the parasitic motions. Based on the stiffness matrix method, static and dynamic models are constructed and optimal design is performed under certain constraints. The finite element analysis results are then given to validate the design model and a prototype of the XY stage is fabricated for performance tests. Open-loop tests show that maximum static and dynamic cross couplings between the two linear motions are below 0.5% and -45 dB, which are low enough to utilize the single-input-single-out control strategies. Finally, according to the identified dynamic model, an inversion-based feedforward controller in conjunction with a proportional-integral-derivative controller is applied to compensate for the nonlinearities and uncertainties. The experimental results show that good positioning and tracking performances are achieved, which verifies the effectiveness of the proposed mechanism and controller design. The resonant frequencies of the loaded stage at 2 kg and 5 kg are 105 Hz and 68 Hz, respectively. Therefore, the performance of the stage is reasonably good in term of a 200 N load capacity. © 2012 American Institute of Physics

High Frequency Single-Stage Multi-Bypass Pulse Tube Cryocooler for 23.8K

NASA Astrophysics Data System (ADS)

Yang, Junling; Hou, Xiaofeng; Yang, Luwei; Zhou, Yuan; Zhang, Liang

2008-03-01

A below 30K single-stage high-frequency multi-bypass pulse tube cryocooler(PTC) is introduced in this paper. At present, the lowest temperature of 27.46K has been achieved with input power of 100W and 23.8K with input power of 200W. Experiments show that if the area of multi-bypass and the length of inertance tube matching well, a better performance of PTC will be obtained.

Performance Improvement of a Single Stage GM Cryocooler at 25 K

NASA Astrophysics Data System (ADS)

Wang, C.; Gifford, P. E.

2008-03-01

To meet the cooling demand of some HTS devices, Cryomech, Inc. has redesigned and improved a single stage GM cryocooler to have a maximum capacity at 25K. The losses in a rotary valve and a low temperature regenerator have been reduced. The improved GM cryocooler provides a cooling capacity of 109 W at 25 K with an input power of 10.4 kW while running with the 50Hz electrical source.

How can recovery be enhanced after single-stage laparoscopic management of CBD stones? Endoscopic treatment versus laparoscopic surgery.

PubMed

Chapuis-Roux, Emilie; Pellissier, Laurent; Browet, Francois; Berthou, Jean Charles; Hakim, Sami; Brazier, Franck; Cosse, Cyril; Delcenserie, Richard; Regimbeau, Jean Marc

2017-07-01

Single-stage management of CBD stones comprises simultaneous common bile duct (CBD) clearance and cholecystectomy. The CBD can be cleared by using endoscopic treatment (ET) or laparoscopic surgery (LS) alone. To determine the most rapid recovery after the single-stage laparoscopic management of CBD stones. Patients with CBD stones treated at either of two centers (one performing ET only and one performing LS only for single-stage treatment) were included. The primary endpoint was "the textbook outcome". The feasibility rate was 74% for ET and 100% for LS (p≤0.001). The proportion of cases with the textbook outcome was higher in the ET group than in the LS-only group (73% vs. 10%; p<0.001). The CBD clearance rate was similar in the ET and LS-only groups (100% vs. 96.6%, respectively; p=0.17). The overall morbidity rate was lower in the ET group than in the LS-only group (23% vs. 29%, p=0.05). Both ET and LS are feasible, safe and effective for clearance of the CBD. ET was better than LS in terms of a less frequent requirement for drainage and a shorter length of hospital stay. LS was associated with a shorter operating time. Copyright © 2017 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Experimental Investigation of a High Pressure Ratio Aspirated Fan Stage

NASA Technical Reports Server (NTRS)

Merchant, Ali; Kerrebrock, Jack L.; Adamczyk, John J.; Braunscheidel, Edward

2004-01-01

The experimental investigation of an aspirated fan stage designed to achieve a pressure ratio of 3.4:1 at 1500 ft/sec is presented in this paper. The low-energy viscous flow is aspirated from diffusion-limiting locations on the blades and flowpath surfaces of the stage, enabling a very high pressure ratio to be achieved in a single stage. The fan stage performance was mapped at various operating speeds from choke to stall in a compressor facility at fully simulated engine conditions. The experimentally determined stage performance, in terms of pressure ratio and corresponding inlet mass flow rate, was found to be in good agreement with the three-dimensional viscous computational prediction, and in turn close to the design intent. Stage pressure ratios exceeding 3:1 were achieved at design speed, with an aspiration flow fraction of 3.5 percent of the stage inlet mass flow. The experimental performance of the stage at various operating conditions, including detailed flowfield measurements, are presented and discussed in the context of the computational analyses. The sensitivity of the stage performance and operability to reduced aspiration flow rates at design and off design conditions are also discussed.

Design and optimization of a single stage centrifugal compressor for a solar dish-Brayton system

NASA Astrophysics Data System (ADS)

Wang, Yongsheng; Wang, Kai; Tong, Zhiting; Lin, Feng; Nie, Chaoqun; Engeda, Abraham

2013-10-01

According to the requirements of a solar dish-Brayton system, a centrifugal compressor stage with a minimum total pressure ratio of 5, an adiabatic efficiency above 75% and a surge margin more than 12% needs to be designed. A single stage, which consists of impeller, radial vaned diffuser, 90° crossover and two rows of axial stators, was chosen to satisfy this system. To achieve the stage performance, an impeller with a 6:1 total pressure ratio and an adiabatic efficiency of 90% was designed and its preliminary geometry came from an in-house one-dimensional program. Radial vaned diffuser was applied downstream of the impeller. Two rows of axial stators after 90° crossover were added to guide the flow into axial direction. Since jet-wake flow, shockwave and boundary layer separation coexisted in the impeller-diffuser region, optimization on the radius ratio of radial diffuser vane inlet to impeller exit, diffuser vane inlet blade angle and number of diffuser vanes was carried out at design point. Finally, an optimized centrifugal compressor stage fulfilled the high expectations and presented proper performance. Numerical simulation showed that at design point the stage adiabatic efficiency was 79.93% and the total pressure ratio was 5.6. The surge margin was 15%. The performance map including 80%, 90% and 100% design speed was also presented.

Understand Centrifugal Compressor stage curves

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

Stadler, E.L.

1986-08-01

Multistage Centrifugal Compressor Performance is generally presented in the form of a composite curve showing discharge pressure and bhp plotted as a function of capacity. This composite curve represents the cumulative performance of each stage performance curve. A simple yet quite accurate means of measuring compressor total performance is to test each stage as a single-stage compressor, usually on air with atmospheric inlets. Stage curves are then generated from the test data and three important variables are plotted: head coefficient, work coefficient and adiabatic efficiency. These variables are plotted against a normalized flow coefficient, Q/N, which is inlet volume flowmore » (cfm) divided by impeller speed (rpm). The nomenclature used to define these stage variables changes from manufacturer to manufacturer; however, the parameters presented are the same. An understanding of each parameter's theoretical derivation and determination from test data will help the engineer reviewing test curves to be more cognizant of the interrelationships between these variables; specifically, how they affect overall machine pressure rise and power consumption.« less

Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

NASA Technical Reports Server (NTRS)

Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

2014-01-01

The measured aerodynamic performance of a compact, high work factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90-bend, and exit guide vane (EGV), is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level are reported for operation between 70 to 105 of design corrected speed, with subcomponent (impeller, diffuser, and exitguide-vane) detailed flow field measurements presented and discussed at the 100 design-speed condition. Individual component losses from measurements are compared with pre-test predictions on a limited basis.

Cultivation of E. coli in single- and ten-stage tower-loop reactors.

PubMed

Adler, I; Schügerl, K

1983-02-01

E. Coli was cultivated in batch and continuous operations in the presence of an antifoam agent in stirred-tank and in single- and ten-stage airlift tower reactors with an outer loop. The maximum specific growth rate, mu(m), the substrate yield coefficient, Y(x/s), the respiratory quotient, RQ, substrate conversion, U(s), the volumetric mass transfer coefficient, K(L)a, the specific interfacial area, a, and the specific power input, P/V(L), were measured and compared. If a medium is used with a concentration of complex substrates (extracts) 2.5 times higher than that of glucose, a spectrum of C sources is available and cell regulation influences reactor performance. Both mu(m) and Y(X/S), which were evaluated in batch reactors, cannot be used for continuous reactors or, when measured in stirred-tank reactors, cannot be employed for tower-loop reactors: mu(m) is higher in the stirred-tank batch than in the tower-loop batch reactor, mu(m) and Y(x/s) are higher in the continuous reactor than in the batch single-stage tower-loop reactor. The performance of the single-stage is better than that of the ten-stage reactor due to the inefficient trays employed. A reduction of the medium recirculation rate reduces OTR, U(s), Pr, and Y(X/S) and causes cell sedimentation and flocculation. The volumetric mass transfer coefficient is reduced with increasing cultivation time; the Sauter bubble diameter, d(s), remains constant and does not depend on operational conditions. An increase in the medium recirculation rate reduces k(L)a. The specific power input, P/V(L), for the single-stage tower loop is much lower with the same k(L)a value than for a stirred tank. The relationship k(L)a vs. P/V(L) evaluated for model media in stirred tanks, can also be used for cultivations in these reactors.

Feasibility study of generating ultra-high harmonic radiation with a single stage echo-enabled harmonic generation scheme

NASA Astrophysics Data System (ADS)

Zhou, Kaishang; Feng, Chao; Wang, Dong

2016-10-01

The echo enabled harmonic generation (EEHG) scheme holds the ability for the generation of fully coherent soft x-ray free-electron laser (FEL) pulses directly from external UV seeding sources. In this paper, we study the feasibility of using a single stage EEHG to generate coherent radiation in the "water window" and beyond. Using the high-order operating modes of the EEHG scheme, intensive numerical simulations have been performed considering various three-dimensional effects. The simulation results demonstrated that coherent soft x-ray radiation at 150th harmonic (1.77 nm) of the seed can be produced by a single stage EEHG. The decreasing of the final bunching factor at the desired harmonic caused by intra beam scattering (IBS) effect has also been analyzed.

Abort performance for a winged-body single-stage to orbit vehicle. M.S. Thesis - George Washington Univ.

NASA Technical Reports Server (NTRS)

Lyon, Jeffery A.

1995-01-01

Optimal control theory is employed to determine the performance of abort to orbit (ATO) and return to launch site (RTLS) maneuvers for a single-stage to orbit vehicle. The vehicle configuration examined is a seven engine, winged-body vehicle, that lifts-off vertically and lands horizontally. The abort maneuvers occur as the vehicle ascends to orbit and are initiated when the vehicle suffers an engine failure. The optimal control problems are numerically solved in discretized form via a nonlinear programming (NLP) algorithm. A description highlighting the attributes of this NLP method is provided. ATO maneuver results show that the vehicle is capable of ascending to orbit with a single engine failure at lift-off. Two engine out ATO maneuvers are not possible from the launch pad, but are possible after launch when the thrust to weight ratio becomes sufficiently large. Results show that single engine out RTLS maneuvers can be made for up to 180 seconds after lift-off and that there are scenarios for which RTLS maneuvers should be performed instead of ATP maneuvers.

Accomplishing the genotype-specific serodiagnosis of single and dual Trypanosoma cruzi infections by flow cytometry Chagas-Flow ATE-IgG2a.

PubMed

Alessio, Glaucia Diniz; de Araújo, Fernanda Fortes; Sales Júnior, Policarpo Ademar; Gomes, Matheus de Souza; Amaral, Laurence Rodrigues do; Pascoal Xavier, Marcelo Antônio; Teixeira-Carvalho, Andréa; de Lana, Marta; Martins-Filho, Olindo Assis

2018-02-01

The methods currently available for genotype-specific diagnosis of T. cruzi infection still present relevant limitations, especially to identify mixed infection. In the present investigation, we have evaluated the performance of Chagas-Flow ATE-IgG2a test for early and late differential diagnosis of single and dual genotype-specific T. cruzi infections. Serum samples from Swiss mice at early and late stages of T. cruzi infection were assayed in parallel batches for genotype-specific diagnosis of single (TcI, TcVI or TcII) and dual (TcI+TcVI, TcVI+TcII or TcII+TcI) infections. The intrinsic reactivity to TcI, TcVI and TcII target antigens, including amastigote (AI/AVI/AII), trypomastigote-(TI/TVI/TII) and epimastigote (EI/EVI/EII), at specific reverse of serum dilutions (500 to 64,000), was employed to provide reliable decision-trees for "early" vs "late", "single vs "dual" and "genotype-specific" serology. The results demonstrated that selective set of attributes "EII 500/EI 2,000/AII 500" were able to provide high-quality accuracy (81%) to segregate early and late stages of T. cruzi infection. The sets "TI 2,000/AI 1,000/EII 1,000" and "TI 8,000/AII 32,000" presented expressive scores to discriminate single from dual T. cruzi infections at early (85%) and late stages (84%), respectively. Moreover, the attributes "TI 4,000/TVI 500/TII 1,000", "TI 16,000/EI 2,000/EII 2,000/AI 500/TVI 500" showed good performance for genotype-specific diagnosis at early stage of single (72%) and dual (80%) T. cruzi infections, respectively. In addition, the attributes "TI 4,000/AII 1,000/EVI 1,000", "TI 64,000/AVI 500/AI 2,000/AII 1,000/EII 4,000" showed moderate performance for genotype-specific diagnosis at late stage of single (69%) and dual (76%) T. cruzi infections, respectively. The sets of decision-trees were assembled to construct a sequential algorithm with expressive accuracy (81%) for serological diagnosis of T. cruzi infection. These findings engender new perspectives for the application of Chagas-Flow ATE-IgG2a method for genotype-specific diagnosis in humans, with relevant contributions for epidemiological surveys as well as clinical and post-therapeutic monitoring of Chagas disease.

Single-session versus staged procedures for elective multivessel percutaneous coronary intervention.

PubMed

Toyota, Toshiaki; Morimoto, Takeshi; Shiomi, Hiroki; Yamaji, Kyohei; Ando, Kenji; Ono, Koh; Shizuta, Satoshi; Saito, Naritatsu; Kato, Takao; Kaji, Shuichiro; Furukawa, Yutaka; Nakagawa, Yoshihisa; Kadota, Kazushige; Horie, Minoru; Kimura, Takeshi

2018-06-01

To clarify the effect of single-session multivessel percutaneous coronary intervention (PCI) strategy relative to the staged multivessel strategy on clinical outcomes in patients with stable coronary artery disease (CAD) or non-ST-elevation acute coronary syndrome. In the Coronary REvascularisation Demonstrating Outcome Study in Kyoto PCI/coronary artery bypass grafting registry cohort-2, there were 2018 patients who underwent elective multivessel PCI. Primary outcome measure was composite of all-cause death, myocardial infarction and stroke at 5-year follow-up. Single-session multivessel PCI and staged multivessel PCI were performed in 707 patients (35.0%) and 1311 patients (65.0%), respectively. The cumulative 5-year incidence of and adjusted risk for the primary outcome measure were not significantly different between the single-session and staged groups (26.7% vs 23.0%, p=0.45; HR 0.91, 95% CI 0.72 to 1.16, p=0.47). The 30-day incidence of all-cause death was significantly higher in the single-session group than in the staged group (1.1% vs 0.2%, p=0.009). However, the causes of death in 11 patients who died within 30 days were generally not related to the procedural complications, but related to the serious clinical status before PCI. For the subgroup analyses including age, gender, extent of CAD, severe chronic kidney disease and heart failure, there was no significant interaction between the subgroup factors and the effect of the single-session strategy relative to the staged strategy for the primary outcome measure. The single-session multivessel PCI strategy was associated with at least comparable 5-year clinical outcomes compared with the staged multivessel PCI, although the prevalence of the single-session strategy was low in the present study. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Summary of Investigations of Mark 25 Aerial-Torpedo Turbine

NASA Technical Reports Server (NTRS)

Schum, Harold J.; Whitney, Warren J.; Buckner, Howard A., Jr.

1950-01-01

The power plant from a Mark 25 aerial torpedo was investigated both as a two-stage turbine and as a single-stage modified turbine to determine the effect on overall performance of nozzle size and shape, first-stage rotor-blade configuration, and axial nozzle-rotor running clearance. Performance was evaluated in terms of brake, rotor, and blade efficiencies. All the performance data were obtained for inlet total to outlet static pressure ratios of 8, 15 (design), and 20 with inlet conditions maintained constant at 95 pounds per square inch gage and 1000 F for rotor speeds from approximately 6000 to 18,000 rpm.

Simulation model of a single-stage lithium bromide-water absorption cooling unit

NASA Technical Reports Server (NTRS)

Miao, D.

1978-01-01

A computer model of a LiBr-H2O single-stage absorption machine was developed. The model, utilizing a given set of design data such as water-flow rates and inlet or outlet temperatures of these flow rates but without knowing the interior characteristics of the machine (heat transfer rates and surface areas), can be used to predict or simulate off-design performance. Results from 130 off-design cases for a given commercial machine agree with the published data within 2 percent.

Single-state electronic ballast with dimming feature and unity power factor

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

Wu, T.F.; Yu, T.H.; Chiang, M.C.

1998-05-01

Analysis, design, and practical consideration of a single-stage electronic ballast with dimming feature and unity power factor are presented in this paper. The proposed single-stage ballast is the combination of a boost converter and a half-bridge series-resonant parallel-loaded inverter. The boost semistage working in the discontinuous conduction mode functions as a power factor corrector and the inverter semistage operated above resonance are employed to ballast the lamp. Replacing the lamp with the plasma model, analysis of the ballast is fulfilled. The dimming feature is carried out by pulse-width modulation (PWM) and variable-frequency controls simultaneously. The proposed single-stage ballast is suitablemore » for applications with moderate power level and low-line voltage while requiring a high-output voltage. It can save a controller, an active switch and its driver, reduce size, and possibly increase system reliability while requiring two additional diodes over a conventional two-stage system. A prototype was implemented to verify the theoretical discussion. The hardware measurements have shown that the desired performance can be achieved feasibly.« less

Laparoscopic Common Bile Duct Exploration for Choledocholithiasis: Analysis of Practice Patterns of Intermountain HealthCare.

PubMed

Gilsdorf, Daniel; Henrichsen, Jake; Liljestrand, Katie; Staheli, Allison; Olsen, Griffin; Narayanan, Prem; Ott, Mark; Morris, David S; Price, Raymond

2018-06-01

The ideal management of common bile duct (CBD) stones remains controversial, whether with single-stage management using laparoscopic CBD exploration (LCBDE) during laparoscopic cholecystectomy, or with 2-stage management using preoperative or postoperative ERCP. We wished to elucidate the practice patterns within our health system, which includes both large urban referral centers and small rural critical access hospitals. We conducted a retrospective data analysis from our 22-hospital, not-for-profit, integrated healthcare system. All patients with a diagnosis of choledocholithiasis who underwent laparoscopic cholecystectomy (LC) and either ERCP or LCBDE for duct clearance between 2008 and 2013 were included. Demographic data, along with disease-specific characteristics and outcomes, were collected and compared. During the study period, 37,301 patients underwent LC. Of these, 1,961 (5.3%) met inclusion criteria. Single-stage management with LC+LCBDE was performed in 28% of patients, and the remaining 72% underwent 2-stage management with ERCP (73% postoperative ERCP, 27% preoperative). Mean total number of procedures was lowest in the LC+LCBDE group vs the post-cholecystectomy ERCP group vs the preoperative ERCP group (mean 1.4 vs 2.1 vs 2.3; p < 0.05). Hospital charges were also lower in the LC+LCBDE group vs post-cholecystectomy ERCP vs preoperative ERCP groups ($9,000 vs $10,800 vs $14,200; p < 0.05). Single-stage vs two-stage management varied greatly between hospitals (from 0% to 93%). Single-stage management of CBD stones resulted in the fewest procedures and lower hospital charges without an increase in complications. Single-stage management (LC+LCBDE) of CBD stones is underused and can offer better value in today's cost-constrained environment. Copyright © 2018 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Single-staged uniportal VATS in the supine position for simultaneous bilateral primary spontaneous pneumothorax.

PubMed

Kim, Kyung Soo

2017-05-15

Simultaneous bilateral primary spontaneous pneumothorax (SBPSP) is rare, but requires surgery on both sides, in patients with definite bilateral bullae to prevent life-threatening conditions. Recently, uniportal video-assisted thoracoscopic surgery (VATS) has been widely accepted as a less invasive technique for the treatment of pneumothorax. Thus, we introduced single-staged uniportal VATS technique in the supine position, for the management of two cases of SBPSP. A 17-year-old boy presented with bilateral spontaneous pneumothorax and he underwent single-staged uniportal VATS in the supine position. Single wide draping in consecutive bilateral approaches removes the needs of changing patients' position. Whole thoracoscopic procedure for wedge resection of bullae lesions was conducted without difficulty. The total operation time took 65 min and the patient discharged 3 days after the operation. The patient was followed for 24 months without recurrence of both sides. Another 18-year-old boy was admitted with bilateral spontaneous pneumothorax and single-staged uniportal VATS was also performed in the supine position. The total operation time took 79 min and the patient discharged on postoperative day 4. He was followed for 19 months without recurrence of both sides. Single-staged uniportal VATS approach yielded satisfactory results from simplicity that not requires position change compared to conventional multi-ports VATS in the lateral position, and with better cosmetics. This technique is thought to be a feasible procedure in selective patients with SBPSP or with contralateral bullae for preventive role.

Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

NASA Technical Reports Server (NTRS)

Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

2015-01-01

The measured aerodynamic performance of a compact, high work-factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90deg-bend, and exit guide vane is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level is reported for operation between 70 to 105 percent of design corrected speed, with subcomponent (impeller, diffuser, and exit-guide-vane) flow field measurements presented and discussed at the 100 percent design-speed condition. Individual component losses from measurements are compared with pre-test CFD predictions on a limited basis.

Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

NASA Technical Reports Server (NTRS)

Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

2014-01-01

The measured aerodynamic performance of a compact, high work-factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90º-bend, and exit guide vane is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level is reported for operation between 70 to 105% of design corrected speed, with subcomponent (impeller, diffuser, and exit-guide-vane) flow field measurements presented and discussed at the 100% design-speed condition. Individual component losses from measurements are compared with pre-test CFD predictions on a limited basis.

One-stage Revision ACL reconstruction with hamstring autograft results in satisfactory outcome

PubMed Central

Kejriwal, Ritwik; Buelow, Jens

2017-01-01

Objectives: Revision anterior cruciate ligament (ACL) reconstruction is associated with poorer outcomes and higher rerupture rates when compared to primary ACL reconstruction. There is also a significant heterogeneity in surgical technique, number of stages, and graft options. We report a large single surgeon case series with hamstring autograft as a graft option. Methods: Observational series of revision ACL reconstructions performed by the senior author between 2005 and 2015 was carried out. Chart reviews and clinic follow-ups were performed with the following recorded – re-rupture rate, radiographic grading of osteoarthritis, KT-1000 arthrometer test, IKDC outcome scores and knee range of motion. All patients underwent single bundle four-strand hamstring autograft performed in one stage with use of new tunnels in majority of the cases. Results: 66 patients underwent hamstring autograft one-stage revision ACL reconstruction by Dr Jens Buelow. Chart review was carried out on all patients, and 26 (39%) were followed up in clinic and/or by phone with a mean follow up of 4.7 years. Outcomes included re-rupture rate of 4.5%, reoperation rate of 12%, mean visual analogue scale score of 7.6, mean side-to-side difference of 2.6 mm for KT-1000 arthrometer test, and mean IKDC score of 79. Of the 17 patients with radiographs, 40% had moderate osteoarthritis (grade 2 or 3) at follow-up. Conclusion: Revision ACL reconstruction can result in a satisfactory outcome when performed with a hamstring autograft in one stage.

Sildenafil exposure and hemodynamic effect after stage II single-ventricle surgery

PubMed Central

Hill, Kevin D.; Tunks, Robert D.; Barker, Piers C. A.; Benjamin, Daniel K.; Cohen-Wolkowiez, Michael; Fleming, Gregory A.; Laughon, Matthew; Li, Jennifer S.

2013-01-01

Objective To determine sildenafil exposure and hemodynamic effect in children after stage II single-ventricle surgery. Design Prospective, dose escalation trial. Setting Single-center, pediatric catheterization laboratory. Patients 12 children post stage II single-ventricle surgical palliation and undergoing elective cardiac catheterization: median age 1.9 years (range: 0.8, 4.0), weight 11 kg (8, 13), 9 females, and 10 with a single right ventricle. Interventions Catheterization and echocardiography performed before and immediately after single-dose intravenous sildenafil (0.125, 0.25, 0.35, or 0.45 mg/kg over 20 minutes). Measurements Peak sildenafil and des-methyl sildenafil concentration, change in hemodynamic parameters measured by cardiac catheterization and echocardiography including indexed pulmonary vascular resistance, and myocardial performance. Main Results Maximum sildenafil concentrations ranged from 92–775 ng/ml and were above the in vitro threshold needed for 77% phosphodiesterase type-5 (PDE-5) inhibition in 80% of subjects and 90% inhibition in 80% of subjects with doses ≥0.35 mg/kg. Sildenafil lowered pulmonary vascular resistance index (PVRI) in all 12 subjects (median PVRI 2.2 [range: 1.6, 7.9]; decreased to 1.7 [1.2, 5.4] WU x m2; p<0.01) with no dose-response effect. Sildenafil improved pulmonary blood flow (+8% [0, 20], p=0.04) and saturations (+2% [0, 16], p=0.04) in those with baseline PVRI ≥2 WU x m2 (n=7). Change in saturations correlated inversely with change in PVRI (r2 = 0.74 p<0.01). Sildenafil also lowered mean blood pressure (−12% [−20, +10]; p=0.04). There was no change in cardiac index and no effect on myocardial performance. There were no adverse events. Conclusions Sildenafil demonstrated non-linear exposure with high inter-individual variability but was well tolerated and effectively lowered PVRI in all subjects. Sildenafil did not acutely improve myocardial performance or increase cardiac index. PMID:23823195

Development of a high-specific-speed centrifugal compressor

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

Rodgers, C.

1997-07-01

This paper describes the development of a subscale single-stage centrifugal compressor with a dimensionless specific speed (Ns) of 1.8, originally designed for full-size application as a high volume flow, low pressure ratio, gas booster compressor. The specific stage is noteworthy in that it provides a benchmark representing the performance potential of very high-specific-speed compressors, of which limited information is found in the open literature. Stage and component test performance characteristics are presented together with traverse results at the impeller exit. Traverse test results were compared with recent CFD computational predictions for an exploratory analytical calibration of a very high-specific-speed impellermore » geometry. The tested subscale (0.583) compressor essentially satisfied design performance expectations with an overall stage efficiency of 74% including, excessive exit casing losses. It was estimated that stage efficiency could be increased to 81% with exit casing losses halved.« less

Advances in single- and multi-stage Stirling-type pulse tube cryocoolers for space applications in NLIP/SITP/CAS

NASA Astrophysics Data System (ADS)

Dang, Haizheng; Tan, Jun; Zha, Rui; Li, Jiaqi; Zhang, Lei; Zhao, Yibo; Gao, Zhiqian; Bao, Dingli; Li, Ning; Zhang, Tao; Zhao, Yongjiang; Zhao, Bangjian

2017-12-01

This paper presents a review of recent advances in single- and multi-stage Stirling-type pulse tube cryocoolers (SPTCs) for space applications developed at the National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences (NLIP/SITP/CAS). A variety of single-stage SPTCs operating at 25-150 K have been developed, including several mid-sized ones operating at 80-110 K. Significant progress has been achieved in coolers operating at 30-40 K which use common stainless steel meshes as regenerator matrices. Another important advance is the micro SPTCs with an overall mass of 300-800 g operating at high frequencies varying from 100 Hz to 400 Hz. The main purpose of developing two-stage SPTCs is to simultaneously acquire cooling capacities at both stages, obviating the need for auxiliary precooling in various applications. The three-stage SPTCs are developed mainly for applications at around 10 K, which are also used for precooling the J-T coolers to achieve further lower temperatures. The four-stage SPTCs are developed to directly achieve the liquid helium temperature for cooling space low-Tc superconducting devices and for the deep space exploration as well. Several typical development programs are described and an overview of the cooler performances is presented.

PET/CT and contrast enhanced CT in single vs. two separate sessions: a cost analysis study.

PubMed

Picchio, M; Mansueto, M; Crivellaro, C; Guerra, L; Marcelli, S; Arosio, M; Sironi, S; Gianolli, L; Grimaldi, A; Messa, C

2012-06-01

Aim of the study was to quantify the economic impact of PET/CT and contrast enhanced (c.e.) CT performed in a single session examination vs. stand-alone modalities in oncological patients. One-hundred-forty-five cancer patients referred to both PET/CT and c.e. CT, to either stage (N.=46) or re-stage (N.=99) the disease, were included. Seventy-two/145 performed both studies in a single session (innovative method) and 73/145 in two different sessions (traditional method). The cost-minimization analysis was performed by evaluating: 1) institutional costs, data obtained by hospital accountability (staff, medical materials, equipment maintenance and depreciation, departments utilities); 2) patients costs, data obtained by a specific survey provided to patients (travel, food, accommodation costs, productivity loss). Economic data analysis showed that the costs for innovative method was lower than those of traditional method, both for Institution (106 € less per test) and for patient (21 € less per patient). The loss of productivity for patient and caregivers resulted lower for the innovative method than the traditional method (3 work-hour less per person). PET/CT and c.e. CT performed in a single session is more cost-effective than stand-alone modalities, by reducing both Institutional and patients costs. These advantages are mainly due to lower Institutional cost (single procedure) and to lower cost related to travel and housing.

Investigation of TESCOM Driveshaft Assembly Failure

DTIC Science & Technology

1998-10-01

ratio, two-stage axial -flow compressor with a corrected tip speed of 1250 ft/sec at design . The flowpath casing diameter downstream of the inlet... Design of a 1250 ft/sec. Low-Aspect-Ratio, Single-Stage Axial -Flow Compressor , AFAPL-TR-79-2096, Air Force Aero Propulsion Laboratory, Wright...The TESCOM compressor described in this report is a 2.5-stage, low aspect ratio, axial -flow compressor . The performance objectives of this compressor

Preoperative Embolization to Improve the Surgical Management and Outcome of Juvenile Nasopharyngeal Angiofibroma (JNA) in a Single Center: 10-Year Experience.

PubMed

Lutz, J; Holtmannspötter, M; Flatz, W; Meier-Bender, A; Berghaus, A; Brückmann, H; Zengel, P

2016-12-01

Juvenile nasopharyngeal angiofibroma (JNA) is a rare benign neoplasm that occurs almost exclusively in the nasopharynx of adolescent male individuals. We performed a retrospective study to determine the efficacy and safety of preoperative embolization and the surgical outcome in patients with JNA in a single-center institution. Fifteen cases undergoing embolization and surgical treatment between April 2003 and February 2013 were evaluated retrospectively. The demographic data, clinical presentation, and treatment were reviewed including the kind of preoperative embolization and different surgical approaches performed. The parameters investigated were the amount of blood loss, the tumor stage, and the rates of recurrence. Subsequently, a comparison was made between patients who had undergone Onyx ® embolization versus those who had been embolized with the standard approach. In these 15 patients (mean age, 15 years), a total of 27 surgical procedures were performed. One patient was at stage Ia, two were at stage Ib, two were at stage IIa, six were at stage IIb, one was at stage IIc, and three were at stage IIIa based on the Radkowsky classification. All patients underwent preoperative embolization and subsequent surgery. The surgical approach and the embolization technique varied and evolved during time. The embolization procedure decreased the intraoperative blood loss to a minimum of 250 ml, and with the advent of intratumoral embolization, the rate of recurrence diminished. Preoperative Onyx ® embolization facilitates the shift in the treatment to endoscopic excision in selected patients, which reduces recurrence rates and overall morbidity.

SSME single crystal turbine blade dynamics

NASA Technical Reports Server (NTRS)

Moss, Larry A.; Smith, Todd E.

1987-01-01

A study was performed to determine the dynamic characteristics of the Space Shuttle main engine high pressure fuel turbopump (HPFTP) blades made of single crystal (SC) material. The first and second stage drive turbine blades of HPFTP were examined. The nonrotating natural frequencies were determined experimentally and analytically. The experimental results of the SC second stage blade were used to verify the analytical procedures. The analytical study examined the SC first stage blade natural frequencies with respect to crystal orientation at typical operating conditions. The SC blade dynamic response was predicted to be less than the directionally solidified blade. Crystal axis orientation optimization indicated the third mode interference will exist in any SC orientation.

Single- versus dual-process models of lexical decision performance: insights from response time distributional analysis.

PubMed

Yap, Melvin J; Balota, David A; Cortese, Michael J; Watson, Jason M

2006-12-01

This article evaluates 2 competing models that address the decision-making processes mediating word recognition and lexical decision performance: a hybrid 2-stage model of lexical decision performance and a random-walk model. In 2 experiments, nonword type and word frequency were manipulated across 2 contrasts (pseudohomophone-legal nonword and legal-illegal nonword). When nonwords became more wordlike (i.e., BRNTA vs. BRANT vs. BRANE), response latencies to nonwords were slowed and the word frequency effect increased. More important, distributional analyses revealed that the Nonword Type = Word Frequency interaction was modulated by different components of the response time distribution, depending on the specific nonword contrast. A single-process random-walk model was able to account for this particular set of findings more successfully than the hybrid 2-stage model. (c) 2006 APA, all rights reserved.

PTT functional recovery in early stage II PTTD after tendon balancing and calcaneal lengthening osteotomy.

PubMed

Brilhault, Jean; Noël, Vincent

2012-10-01

The decision to offer surgery for Stage II posterior tibial tendon deficiency (PTTD) is a difficult one since orthotic treatment has been documented to be a viable alternative to surgery at this stage. Taking this into consideration we limited our treatment to bony realignment by a lengthening calcaneus Evans osteotomy and tendon balancing. The goal of the study was to clinically evaluate PTT functional recovery with this procedure. The patient population included 17 feet in 13 patients. Inclusion was limited to early Stage II PTTD flatfeet with grossly intact but deficient PTT. Deficiency was assessed by the lack of hindfoot inversion during single heel rise test. The surgical procedure included an Evans calcaneal opening wedge osteotomy with triceps surae and peroneus brevis tendon lengthening. PTT function at follow up was evaluated by an independent examiner. Evaluation was performed at an average of 4 (range, 2 to 6.3) years. One case presented postoperative subtalar pain that required subtalar fusion. Every foot could perform a single heel rise with 13 feet having active inversion of the hindfoot during elevation. The results of this study provide evidence of PTT functional recovery without augmentation in early Stage II. It challenges our understanding of early Stage II PTTD as well as the surgical guidelines recommending PTT augmentation at this specific stage.

Factors affecting the surgical approach and timing of bilateral adrenalectomy.

PubMed

Lan, Billy Y; Taskin, Halit E; Aksoy, Erol; Birsen, Onur; Dural, Cem; Mitchell, Jamie; Siperstein, Allan; Berber, Eren

2015-07-01

Laparoscopic adrenalectomy has gained widespread acceptance. However, the optimal surgical approach to laparoscopic bilateral adrenalectomy has not been clearly defined. The aim of this study is to analyze the patient and intraoperative factors affecting the feasibility and outcome of different surgical approaches to define an algorithm for bilateral adrenalectomy. Between 2000 and 2013, all patients who underwent bilateral adrenalectomy at a single institution were selected for retrospective analysis. Patient factors, surgical approach, operative outcomes, and complications were analyzed. From 2000 to 2013, 28 patients underwent bilateral adrenalectomy. Patient diagnoses included Cushing's disease (n = 19), pheochromocytoma (n = 7), and adrenal metastasis (n = 2). Of these 28 patients, successful laparoscopic adrenalectomy was performed in all but 2 patients. Twenty-three out of the 26 adrenalectomies were completed in a single stage, while three were performed as a staged approach due to deterioration in intraoperative respiratory status in two patients and patient body habitus in one. Of the adrenalectomies completed using the minimally invasive approach, a posterior retroperitoneal (PR) approach was performed in 17 patients and lateral transabdominal (LT) approach in 9 patients. Patients who underwent a LT approach had higher BMI, larger tumor size, and other concomitant intraabdominal pathology. Hospital stay for laparoscopic adrenalectomy was 3.5 days compared to 5 and 12 days for the two open cases. There were no 30-day hospital mortality and 5 patients had minor complications for the entire cohort. A minimally invasive operation is feasible in 93% of patients undergoing bilateral adrenalectomy with 65% of adrenalectomies performed using the PR approach. Indications for the LT approach include morbid obesity, tumor size >6 cm, and other concomitant intraabdominal pathology. Single-stage adrenalectomies are feasible in most patients, with prolonged operative time causing respiratory instability being the main indication for a staged approach.

Simulator Study of Helmet-Mounted Symbology System Concepts in Degraded Visual Environments.

PubMed

Cheung, Bob; McKinley, Richard A; Steels, Brad; Sceviour, Robert; Cosman, Vaughn; Holst, Peter

2015-07-01

A sudden loss of external visual cues during critical phases of flight results in spatial disorientation. This is due to undetected horizontal and vertical drift when there is little tolerance for error and correction delay as the helicopter is close to the ground. Three helmet-mounted symbology system concepts were investigated in the simulator as potential solutions for the legacy Griffon helicopters. Thirteen Royal Canadian Air Force (RCAF) Griffon pilots were exposed to the Helmet Display Tracking System for Degraded Visual Environments (HDTS), the BrownOut Symbology System (BOSS), and the current RCAF AVS7 symbology system. For each symbology system, the pilot performed a two-stage departure and a single-stage approach. The presentation order of the symbology systems was randomized. Objective performance metrics included aircraft speed, altitude, attitude, and distance from the landing point. Subjective measurements included situation awareness, mental effort, perceived performance, perceptual cue rating, and NASA Task Load Index. Repeated measures analysis of variance and subsequent planned comparison for all the objective and subjective measurements were performed between the AVS7, HDTS, and BOSS. Our results demonstrated that HDTS and BOSS showed general improvement over AVS7 in two-stage departure. However, only HDTS performed significantly better in heading error than AVS7. During the single-stage approach, BOSS performed worse than AVS7 in heading root mean square error, and only HDTS performed significantly better in distance to landing point and approach heading than the others. Both the HDTS and BOSS possess their own limitations; however, HDTS is the pilots' preferred flight display.

Performance of the rebuilt SUERC single-stage accelerator mass spectrometer

NASA Astrophysics Data System (ADS)

Shanks, Richard P.; Ascough, Philippa L.; Dougans, Andrew; Gallacher, Paul; Gulliver, Pauline; Rood, Dylan H.; Xu, Sheng; Freeman, Stewart P. H. T.

2015-10-01

The SUERC bipolar single-stage accelerator mass spectrometer (SSAMS) has been dismantled and rebuilt to accommodate an additional rotatable pre-accelerator electrostatic spherical analyser (ESA) and a second ion source injector. This is for the attachment of an experimental positive-ion electron cyclotron resonance (ECR) ion source in addition to a Cs-sputter source. The ESA significantly suppresses oxygen interference to radiocarbon detection, and remaining measurement interference is now thought to be from 13C injected as 13CH molecule scattering off the plates of a second original pre-detector ESA.

40 K single-stage coaxial pulse tube cryocoolers

NASA Astrophysics Data System (ADS)

Dang, Haizheng

2012-04-01

Several 40 K single-stage coaxial high frequency pulse tube cryocoolers (PTCs) have been developed to provide reliable and low-noise cooling for GaAs/AlGaAs Quantum-Well infrared photodetectors (QWIPs). The inertance tubes together with the gas reservoir become the only phase shifter to guarantee the required long-term stability. The mixed regenerator consisting of three segments has been developed to enhance the overall regenerator performance. At present, the cooler prototype has achieved a no-load temperature of 29.7 K and can typically provide 860 mW cooling at 40 K with 200 W electric input power rejecting at 300 K. The performance characteristics such as the temperature stability and ambient temperature adaptability are also presented.

Emergency skill training--a randomized controlled study on the effectiveness of the 4-stage approach compared to traditional clinical teaching.

PubMed

Greif, Robert; Egger, Lars; Basciani, Reto M; Lockey, Andrew; Vogt, Andreas

2010-12-01

The "4-stage approach" has been widely accepted for practical skill training replacing the traditional 2 stages ("see one, do one"). However, the superior effectiveness of the 4-stage approach was never proved. To evaluate whether skill training with the 4-stage approach results in shorter performance time needed for a successful percutaneous needle-puncture cricothyroidotomy, and consequently in a reduced number of attempts needed to perform the skill in <60s compared to traditional teaching. Randomized controlled single-blinded parallel group study at the University Hospital Bern. With IRB approval and informed consent 128 undergraduate medical students were randomized in four groups: traditional teaching, no stage 2, no stage 3, and 4-stage approach for the training of cricothyroidotomy. Everyone watched a video of the cricothyroidotomy as stage 1 followed by skill training in the respective teaching group. Participants had to perform the cricothyroidotomy 10 times on skin-covered pig larynxes. Performance time was measured from skin palpation to trachea ventilation. Study participants filled out a self-rating on competency during the training. Performance time for each attempt was comparable in all groups and improved similarly to reach a performance time of <60 s. Self-rating revealed that all groups felt equally competent throughout. Even if the 4-stage approach is widely accepted and used as a didactic method for skill teaching we could not find evidence that its use or omitting stage 2 or 3 results in superior learning of an emergency skill compared to traditional teaching. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Liquid oxygen turbopump technology

NASA Technical Reports Server (NTRS)

Nielson, C. E.

1981-01-01

A small, high-pressure, LOX turbopump was designed, fabricated and tested. The pump is a single-stage centrifugal type with power to the pump supplied by a single-stage partial-admission axial-impulse turbine. Design conditions included an operating speed of 7330 rad/s (70,000 rpm), pump discharge pressure of 2977 N/sqcm (4318 psia), and a pump flowrate of 16.4 Kg/s (36.21 lb/s). The turbopump contains a self-compensating axial thrust balance piston to eliminate axial thrust loads on the bearings during steady-state operation. Testing of the turbopump was achieved usng a gaseous hydrogen high-pressure flow to drive the turbine, which generally is propelled by LOX/LH2 combustion products, at 1041K (1874 R) inlet temperature and at a design pressure ratio of 1.424. Test data obtained with the turbopump are presented which include head-flow-efficiency performance, suction performance, balance piston performance and LOX seal performance. Mechanical performance of the turbopump is also discussed.

Accomplishing the genotype-specific serodiagnosis of single and dual Trypanosoma cruzi infections by flow cytometry Chagas-Flow ATE-IgG2a

PubMed Central

Alessio, Glaucia Diniz; de Araújo, Fernanda Fortes; Sales Júnior, Policarpo Ademar; Gomes, Matheus de Souza; do Amaral, Laurence Rodrigues; Pascoal Xavier, Marcelo Antônio; Teixeira-Carvalho, Andréa; de Lana, Marta

2018-01-01

The methods currently available for genotype-specific diagnosis of T. cruzi infection still present relevant limitations, especially to identify mixed infection. In the present investigation, we have evaluated the performance of Chagas-Flow ATE-IgG2a test for early and late differential diagnosis of single and dual genotype-specific T. cruzi infections. Serum samples from Swiss mice at early and late stages of T. cruzi infection were assayed in parallel batches for genotype-specific diagnosis of single (TcI, TcVI or TcII) and dual (TcI+TcVI, TcVI+TcII or TcII+TcI) infections. The intrinsic reactivity to TcI, TcVI and TcII target antigens, including amastigote (AI/AVI/AII), trypomastigote-(TI/TVI/TII) and epimastigote (EI/EVI/EII), at specific reverse of serum dilutions (500 to 64,000), was employed to provide reliable decision-trees for “early” vs “late”, “single vs “dual” and “genotype-specific” serology. The results demonstrated that selective set of attributes “EII 500/EI 2,000/AII 500” were able to provide high-quality accuracy (81%) to segregate early and late stages of T. cruzi infection. The sets “TI 2,000/AI 1,000/EII 1,000” and “TI 8,000/AII 32,000” presented expressive scores to discriminate single from dual T. cruzi infections at early (85%) and late stages (84%), respectively. Moreover, the attributes “TI 4,000/TVI 500/TII 1,000”, “TI 16,000/EI 2,000/EII 2,000/AI 500/TVI 500” showed good performance for genotype-specific diagnosis at early stage of single (72%) and dual (80%) T. cruzi infections, respectively. In addition, the attributes “TI 4,000/AII 1,000/EVI 1,000”, “TI 64,000/AVI 500/AI 2,000/AII 1,000/EII 4,000” showed moderate performance for genotype-specific diagnosis at late stage of single (69%) and dual (76%) T. cruzi infections, respectively. The sets of decision-trees were assembled to construct a sequential algorithm with expressive accuracy (81%) for serological diagnosis of T. cruzi infection. These findings engender new perspectives for the application of Chagas-Flow ATE-IgG2a method for genotype-specific diagnosis in humans, with relevant contributions for epidemiological surveys as well as clinical and post-therapeutic monitoring of Chagas disease. PMID:29462135

Preliminary Design Optimization For A Supersonic Turbine For Rocket Propulsion

NASA Technical Reports Server (NTRS)

Papila, Nilay; Shyy, Wei; Griffin, Lisa; Huber, Frank; Tran, Ken; McConnaughey, Helen (Technical Monitor)

2000-01-01

In this study, we present a method for optimizing, at the preliminary design level, a supersonic turbine for rocket propulsion system application. Single-, two- and three-stage turbines are considered with the number of design variables increasing from 6 to 11 then to 15, in accordance with the number of stages. Due to its global nature and flexibility in handling different types of information, the response surface methodology (RSM) is applied in the present study. A major goal of the present Optimization effort is to balance the desire of maximizing aerodynamic performance and minimizing weight. To ascertain required predictive capability of the RSM, a two-level domain refinement approach has been adopted. The accuracy of the predicted optimal design points based on this strategy is shown to he satisfactory. Our investigation indicates that the efficiency rises quickly from single stage to 2 stages but that the increase is much less pronounced with 3 stages. A 1-stage turbine performs poorly under the engine balance boundary condition. A portion of fluid kinetic energy is lost at the turbine discharge of the 1-stage design due to high stage pressure ratio and high-energy content, mostly hydrogen, of the working fluid. Regarding the optimization technique, issues related to the design of experiments (DOE) has also been investigated. It is demonstrated that the criteria for selecting the data base exhibit significant impact on the efficiency and effectiveness of the construction of the response surface.

Application of dual-fuel propulsion to a single stage AMLS vehicle

NASA Technical Reports Server (NTRS)

Lepsch, Roger A., Jr.; Stanley, Douglas O.; Unal, Resit

1993-01-01

As part of NASA's Advanced Manned Launch System (AMLS) study to determine a follow-on, or complement, to the Space Shuttle, a reusable single-stage-to-orbit concept utilizing dual-fuel rocket propulsion has been examined. Several dual-fuel propulsion concepts were investigated. These include: a separate engine concept combining Russian RD-170 kerosene-fueled engines with SSME-derivative engines; the kerosene and hydrogen-fueled Russian RD-701 engine concept; and a dual-fuel, dual-expander engine concept. Analysis to determine vehicle weight and size characteristics was performed using conceptual level design techniques. A response surface methodology for multidisciplinary design was utilized to optimize the dual-fuel vehicle concepts with respect to several important propulsion system and vehicle design parameters in order to achieve minimum empty weight. Comparisons were then made with a hydrogen-fueled reference, single-stage vehicle. The tools and methods employed in the analysis process are also summarized.

Performance improvement of coherent free-space optical communication with quadrature phase-shift keying modulation using digital phase estimation.

PubMed

Li, Xueliang; Geng, Tianwen; Ma, Shuang; Li, Yatian; Gao, Shijie; Wu, Zhiyong

2017-06-01

The performance of coherent free-space optical (CFSO) communication with phase modulation is limited by both phase fluctuations and intensity scintillations induced by atmospheric turbulence. To improve the system performance, one effective way is to use digital phase estimation. In this paper, a CFSO communication system with quadrature phase-shift keying modulation is studied. With consideration of the effects of log-normal amplitude fluctuations and Gauss phase fluctuations, a two-stage Mth power carrier phase estimation (CPE) scheme is proposed. The simulation results show that the phase noise can be suppressed greatly by this scheme, and the system symbol error rate performance with the two-stage Mth power CPE can be three orders lower than that of the single-stage Mth power CPE. Therefore, the two-stage CPE we proposed can contribute to the performance improvements of the CFSO communication system and has determinate guidance sense to its actual application.

Performance of high intensity fed-batch mammalian cell cultures in disposable bioreactor systems.

PubMed

Smelko, John Paul; Wiltberger, Kelly Rae; Hickman, Eric Francis; Morris, Beverly Janey; Blackburn, Tobias James; Ryll, Thomas

2011-01-01

The adoption of disposable bioreactor technology as an alternate to traditional nondisposable technology is gaining momentum in the biotechnology industry. Evaluation of current disposable bioreactors systems to sustain high intensity fed-batch mammalian cell culture processes needs to be explored. In this study, an assessment was performed comparing single-use bioreactors (SUBs) systems of 50-, 250-, and 1,000-L operating scales with traditional stainless steel (SS) and glass vessels using four distinct mammalian cell culture processes. This comparison focuses on expansion and production stage performance. The SUB performance was evaluated based on three main areas: operability, process scalability, and process performance. The process performance and operability aspects were assessed over time and product quality performance was compared at the day of harvest. Expansion stage results showed disposable bioreactors mirror traditional bioreactors in terms of cellular growth and metabolism. Set-up and disposal times were dramatically reduced using the SUB systems when compared with traditional systems. Production stage runs for both Chinese hamster ovary and NS0 cell lines in the SUB system were able to model SS bioreactors runs at 100-, 200-, 2,000-, and 15,000-L scales. A single 1,000-L SUB run applying a high intensity fed-batch process was able to generate 7.5 kg of antibody with comparable product quality. Copyright © 2011 American Institute of Chemical Engineers (AIChE).

Predicting Jakarta composite index using hybrid of fuzzy time series and support vector regression models

NASA Astrophysics Data System (ADS)

Febrian Umbara, Rian; Tarwidi, Dede; Budi Setiawan, Erwin

2018-03-01

The paper discusses the prediction of Jakarta Composite Index (JCI) in Indonesia Stock Exchange. The study is based on JCI historical data for 1286 days to predict the value of JCI one day ahead. This paper proposes predictions done in two stages., The first stage using Fuzzy Time Series (FTS) to predict values of ten technical indicators, and the second stage using Support Vector Regression (SVR) to predict the value of JCI one day ahead, resulting in a hybrid prediction model FTS-SVR. The performance of this combined prediction model is compared with the performance of the single stage prediction model using SVR only. Ten technical indicators are used as input for each model.

Improving adsorption cryocoolers by multi-stage compression and reducing void volume

NASA Technical Reports Server (NTRS)

Bard, S.

1986-01-01

It is shown that the performance of gas adsorption cryocoolers is greatly improved by using adsorbents with low void volume within and between individual adsorbent particles (reducing void volumes in plumbing lines), and by compressing the working fluid in more than one stage. Refrigerator specific power requirements and compressor volumetric efficiencies are obtained in terms of adsorbent and plumbing line void volumes and operating pressures for various charcoal adsorbents using an analytical model. Performance optimization curves for 117.5 and 80 K charcoal/nitrogen adsorption cryocoolers are given for both single stage and multistage compressor systems, and compressing the nitrogen in two stages is shown to lower the specific power requirements by 18 percent for the 117.5 K system.

Core compressor exit stage study. Volume 2: Data and performance report for the baseline configuration

NASA Technical Reports Server (NTRS)

Wisler, D. C.

1980-01-01

The objective of the program is to develop rear stage blading designs that have lower losses in their endwall boundary layer regions. The overall technical approach in this efficiency improvement program utilized General Electric's Low Speed Research Compressor as the principal investigative tool. Tests were conducted in two ways: using four identical stages of blading so that test data would be obtained in a true multistage environment and using a single stage of blading so that comparison with the multistage test results could be made.

Pediatric Liver Transplant For Hepatoblastoma: A Single-Center Experience.

PubMed

Kirnap, Mahir; Ayvazoglu Soy, Ebru; Ozcay, Figen; Moray, Gokhan; Ozdemir, Binnaz Handan; Haberal, Mehmet

2017-02-01

Our aim was to analyze our experience with orthotopic liver transplant for hepatoblastoma patients. We performed a single-center retrospective analysis of 6 orthotopic liver transplant cases in children with hepatoblastoma from 2001 to March 2015. We evaluated patient demographic features, pretreatment extent of disease stage, type of transplant, change in serum alpha-fetoprotein levels, complications, and follow-up results. Orthotopic liver transplant was performed for pretreatment extent of disease stage III with a central location (n = 3) and pretreatment extent of disease stage IV (n = 3). All children underwent living-donor orthotopic liver transplant. Postoperative serum alpha-fetoprotein levels remained below 10 ng/mL during the follow-up period in 3 patients who were free of recurrences or metastases. Five patients were free of tumor recurrences at a median follow-up of 29.9 months. The limited number of cases we present without long-term follow-up of orthotopic liver transplant for unresectable hepatoblastoma seemed to show good clinical results.

Feasibility study for long lifetime helium dewar

NASA Technical Reports Server (NTRS)

Parmley, R. T.

1981-01-01

A feasible concept for a launchable three year lifetime helium dewar was investigted. Current helium dewar designs were examined to see where the largest potential reductions in parasitic heat loads can be made. The study was also devoted to examining support concepts. The support concept chosen, a passive orbital disconnect strut (PODS), has an orbital support conductance that is lower by more than an order of magnitude over current tension band supports. This lower support conductance cuts the total dewar weight in half for the same three year life time requirements. Effort was also concentrated on efficient wire feed through designs and vapor cooling of the multilayer insulation, supports, wire feed throughs and plumbing penetrations. A single stage helium dewar vs. dual stage dewars with a guard cryogen of nitrogen or neon was examined. The single stage dewar concept was selected. Different support concepts were analyzed from which the PODS support concepts was chosen. A preliminary design of the dewar was thermally and structurally analyzed and laid out including system weights, thermal performance and performance sensitivities.

Hypersonic airbreathing vehicle visions and enhancing technologies

NASA Astrophysics Data System (ADS)

Hunt, James L.; Lockwood, Mary Kae; Petley, Dennis H.; Pegg, Robert J.

1997-01-01

This paper addresses the visions for hypersonic airbreathing vehicles and the advanced technologies that forge and enhance the designs. The matrix includes space access vehicles (single-stage-to-orbit (SSTO), two-stage-to-orbit (2STO) and three-stage-to-orbit (3STO)) and endoatmospheric vehicles (airplanes—missiles are omitted). The characteristics, the performance potential, the technologies and the synergies will be discussed. A common design constraint is that all vehicles (space access and endoatmospheric) have enclosed payload bays.

Undergraduate Double Majors' Perceptions of Performer and Teacher Identity Development

ERIC Educational Resources Information Center

Sieger, Crystal

2016-01-01

The purpose of this research was to investigate music performer/music teacher identity by examining double majors in various stages of their programs of study aspiring to become a performer and music educator. Unlike their single-major peers, double majors cope with additional challenges as they simultaneously develop both identities, determining…

Callus Distraction Versus Single-Stage Lengthening With Bone Graft for Treatment of Brachymetatarsia: A Systematic Review.

PubMed

Jones, Marc D; Pinegar, David M; Rincker, Sarah A

2015-01-01

Brachymetatarsia deformity is a cosmetically displeasing anomaly that can become physically symptomatic. The surgical techniques most commonly used to repair the anomaly include single-stage lengthening with a bone graft, callus distraction, or a combination of bone grafting and callus distraction. A systematic review of the published data was performed to compare the outcomes of these 3 surgical procedures. A total of 61 studies reporting the use of callus distraction or single-stage lengthening, or both, for the treatment of brachymetatarsia were included in the present review. The incidence of major postoperative complications after callus distraction, single-stage lengthening, and the combination procedure was 49 (12.62%), 13 (3.72%), and 3 (33.33%), respectively. The number of minor complications with callus distraction, single-stage lengthening, and the combination procedure was 152 (39.18%), 55 (15.76%), and 1 (11.11%); the mean percentage of the original length achieved was 37.36%, 25.98% and 36.00%; and the mean length achieved was 17.5, 13.2, and 14.0 mm, respectively. The healing index (mo/cm) and healing time was 2.31 and 16.04 weeks, 1.90 and 9.35 weeks, and 3.93 and 14.62 weeks for callus distraction, single-stage lengthening, and the combination procedure, respectively. Our findings indicate that the callus distraction technique is associated with greater length gained but results in greater complication rates and requires almost twice the time to heal. Single-stage lengthening with a bone graft was associated with fewer complications and faster healing times than callus distraction but with lesser gains in length. From the information reported in the studies we reviewed, the prevalence of bilateral brachymetatarsia was 44.52%, and the female/male ratio was 13.7:1. Both of these findings seem to contradict the usual data given (72% for bilateral brachymetatarsia and a female/male ratio of 25:1). Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Single organ metastatic disease and local disease status, prognostic factors for overall survival in stage IV non-small cell lung cancer: Results from a population-based study.

PubMed

Hendriks, L E; Derks, J L; Postmus, P E; Damhuis, R A; Houben, R M A; Troost, E G C; Hochstenbag, M M; Smit, E F; Dingemans, A-M C

2015-11-01

To analyse the prognostic impact on overall survival (OS) of single versus multiple organ metastases, organ affected, and local disease status in a population based stage IV non-small cell lung cancer (NSCLC) cohort. In this observational study, data were analysed of all histologically confirmed stage IV NSCLC patients diagnosed between 1 January 2006 and 31 December 2012 registered in the Netherlands Cancer Registry. Location of metastases before treatment was registered. Multivariable survival analyses [age, gender, histology, M-status, local disease status, number of involved organs, actual organ affected] were performed for all patients and for an (18)fluorodeoxyglucose-positron emission tomography ((18)FDG-PET)-staged subgroup. 11,094 patients were selected: 60% male, mean age 65 years, 73% adenocarcinoma. Median OS for 1 (N = 5676), 2 (N = 3280), and ⩾ 3 (N = 2138) metastatically affected organs was 6.7, 4.3, 2.8 months, respectively (p < 0.001). Hazard ratio (HR) for 2 versus 1 organ(s) was 1.33 (p < 0.001), for ⩾ 3 versus 1 organ(s) 1.91 (p < 0.001). Results were confirmed in the (18)FDG-PET-staged cohort (N = 1517): patients with single organ versus 2 and ⩾ 3 organ metastases had higher OS (8.6, 5.7, 3.8 months, HR 1.40 and 2.17, respectively, p < 0.001). In single organ metastases, OS for low versus high TN-status was 8.5 versus 6.5 months [HR 1.40 (p < 0 .001)]. (18)FDG-PET-staged single organ metastases patients with low TN-status had a superior OS than those with high TN-status (11.6 versus 8.2 months, HR 1.62, p < 0.001). Patients with single organ metastases stage IV NSCLC have a favourable prognosis, especially in combination with low TN status. They have to be regarded as a separate subgroup of stage IV disease. Copyright © 2015 Elsevier Ltd. All rights reserved.

Automatic sleep stage classification using two facial electrodes.

PubMed

Virkkala, Jussi; Velin, Riitta; Himanen, Sari-Leena; Värri, Alpo; Müller, Kiti; Hasan, Joel

2008-01-01

Standard sleep stage classification is based on visual analysis of central EEG, EOG and EMG signals. Automatic analysis with a reduced number of sensors has been studied as an easy alternative to the standard. In this study, a single-channel electro-oculography (EOG) algorithm was developed for separation of wakefulness, SREM, light sleep (S1, S2) and slow wave sleep (S3, S4). The algorithm was developed and tested with 296 subjects. Additional validation was performed on 16 subjects using a low weight single-channel Alive Monitor. In the validation study, subjects attached the disposable EOG electrodes themselves at home. In separating the four stages total agreement (and Cohen's Kappa) in the training data set was 74% (0.59), in the testing data set 73% (0.59) and in the validation data set 74% (0.59). Self-applicable electro-oculography with only two facial electrodes was found to provide reasonable sleep stage information.

Rotor redesign for a highly loaded 1800 ft/sec tip speed fan, 2

NASA Technical Reports Server (NTRS)

Bolt, C. R.

1980-01-01

Tests were conducted on a 0.5 hub/tip ratio single-stage fan designed to produce a pressure ratio of 2.280 at an efficiency of 83.8 percent with a rotor tip speed of 548.6 m/sec (1800 ft/sec). The rotor was designed utilizing a quasi three dimensional design system and four-part, multiple-circular-arc airfoil sections. The rotor is the third in a series of single-stage fans that have included a precompression airfoil design and a multiple-circular-arc airfoil design. The stage achieved a peak efficiency of 82.8 percent after performance had deteriorated by 0.6 of a point. The design mass flow was achieved at the peak efficiency point, and the stage total pressure ratio was 2.20, which is lower than the design goal of 2.28. The surge margin of 13% from the peak efficiency point exceeded the design goal of 7%.

A grid-connected single-phase photovoltaic micro inverter

NASA Astrophysics Data System (ADS)

Wen, X. Y.; Lin, P. J.; Chen, Z. C.; Wu, L. J.; Cheng, S. Y.

2017-11-01

In this paper, the topology of a single-phase grid-connected photovoltaic (PV) micro-inverter is proposed. The PV micro-inverter consists of DC-DC stage with high voltage gain boost and DC-AC conversion stage. In the first stage, we apply the active clamp circuit and two voltage multipliers to achieve soft switching technology and high voltage gain. In addition, the flower pollination algorithm (FPA) is employed for the maximum power point tracking (MPPT) in the PV module in this stage. The second stage cascades a H-bridge inverter and LCL filter. To feed high quality sinusoidal power into the grid, the software phase lock, outer voltage loop and inner current loop control method are adopted as the control strategy. The performance of the proposed topology is tested by Matlab/Simulink. A PV module with maximum power 300W and maximum power point voltage 40V is applied as the input source. The simulation results indicate that the proposed topology and the control strategy are feasible.

Comparative Study of Survival following Videothoracoscopic Lobectomy Procedures for Lung Cancer: Single- versus Multiple-port Approaches.

PubMed

Borro, José M; Regueiro, Francisco; Pértega, Sonia; Constenla, Manuel; Pita, Salvador

2017-04-01

Video-assisted thoracoscopic surgery has become the technique of choice in the early stages of lung cancer in many centers although there is no evidence that all of the surgical approaches achieve the same long-term survival. We carried out a retrospective review of 276 VATS lobectomies performed in our department, analyzing age, sex, comorbidities, current smoker, FEV1 and FCV, surgical approach, TNM and pathological stage, histologic type, neoadjuvant or coadjuvant chemotherapy, relapse and metastasis time, with the main aim of evaluating the survival rate and disease-free time, especially with regard to the two/three versus single port approach. The one/four year global survival rate was 88.1 and 67.6% respectively. Bivariate analysis found that the variables associated with survival are comorbidity, histological type, stage, surgical approach and need for chemotherapy. When we independently analyzed the surgical approach, we found a lower survival rate in the single-port group vs. the two/three-port group (VATS). Stratifying by tumoral stage (stage I) and by tumor size (T2) survival was significantly lower for patients with single-port group in comparison to VATS approach. In the multivariate analysis, single-port group is associated with a higher risk of death (HR=1.78). In analyzing disease-free survival, differences were found in both cases in favor of two/three port VATS: p=.093 for local relapses and p=.091 for the development of metastasis. These results challenge the use of the single port technique in malignant lung pathologies, suggesting the need for clinical trials in order to identify the role this technique may have in lung cancer surgery. Copyright © 2016 SEPAR. Publicado por Elsevier España, S.L.U. All rights reserved.

Single-Port Video-Assisted Thoracoscopic Major Lung Resections: Experience with 150 Consecutive Cases.

PubMed

Ng, Calvin S H; Kim, Hyun Koo; Wong, Randolph H L; Yim, Anthony P C; Mok, Tony S K; Choi, Young Ho

2016-06-01

Background Video-assisted thoracic surgery (VATS) for major lung resection has undergone major changes from three or four-port approach to the recently possible single-port VATS approach. Outcomes following single-port VATS major lung resection are analyzed to determine safety and efficacy. Methods A prospective database of 150 consecutive patients who underwent single-port VATS major lung resection between March 2012 and January 2014 was reviewed. Patient demographics, perioperative parameters, histopathology, and outcomes up to follow-up of 2 years were analyzed by descriptive and Kaplan-Meier survival statistics. Results Single-port VATS major lung resection was successfully performed in 142 patients (conversion rate 5.3%) for both malignant and benign diseases of the lung. Overall, 130 patients (87%) had nonsmall-cell lung carcinoma (NSCLC), 9 (6%) had other types of primary lung cancer, and the remaining for secondary malignancies and benign diseases. Among the 130 patients with NSCLC, 93 (71.5%) were stage I, 28 were stage II (21.5%), and 9 (7%) were stage III or greater. There was no intraoperative or 30-day mortality. However, one perioperative death occurred on day 49, and another on day 60 postoperatively due to infective causes. The overall 2-year mortality rate for all patients was 3%. The disease-free survival rate for subgroups, stage I NSCLC, and stage II or greater NSCLC were 96 and 83%, respectively. Conclusions Single-port VATS major lung resection for malignant and benign lung diseases is associated with low perioperative morbidity and mortality. Disease-free survival rates for NSCLC are acceptable and comparable with conventional VATS. Georg Thieme Verlag KG Stuttgart · New York.

Delayed Single Stage Perineal Posterior Urethroplasty.

PubMed

Ali, Shahzad; Shahnawaz; Shahzad, Iqbal; Baloch, Muhammad Umar

2015-06-01

To determine the delayed single stage perineal posterior urethroplasty for treatment of posterior urethral stricture/distraction defect. Descriptive case series. Department of Urology, Jinnah Postgraduate Medical Centre, Karachi, from January 2009 to December 2011. Patients were selected for delayed single stage perineal posterior urethroplasty for treatment of posterior urethral stricture / distraction defect. All were initially suprapubically catheterized followed by definitive surgery after at least 3 months. Thirty male patients were analyzed with a mean follow-up of 10 months, 2 patients were excluded as they developed failure in first 3 months postoperatively. Mean patient's age was 26.25 ± 7.9 years. On follow-up, 7 patients (23.3%) experienced recurrent stricture during first 10 months. Five (16.6%) patients were treated successfully with single direct visual internal urethrotomy. Two patients (6.6%) had more than one direct visual internal urethrotomy and considered failed. Re-do perineal urethroplasty was eventually performed. The overall success rate was 93.3% with permissive criteria allowing single direct visual internal urethrotomy and 76.6% with strict criteria allowing no more procedures postoperatively. Posterior anastomotic urethroplasty offers excellent long-term results to patients with posterior urethral trauma and distraction defect even after multiple prior procedures.

Improving Dual-Task Control With a Posture-Second Strategy in Early-Stage Parkinson Disease.

PubMed

Huang, Cheng-Ya; Chen, Yu-An; Hwang, Ing-Shiou; Wu, Ruey-Meei

2018-03-31

To examine the task prioritization effects on postural-suprapostural dual-task performance in patients with early-stage Parkinson disease (PD) without clinically observed postural symptoms. Cross-sectional study. Participants performed a force-matching task while standing on a mobile platform, and were instructed to focus their attention on either the postural task (posture-first strategy) or the force-matching task (posture-second strategy). University research laboratory. Individuals (N=16) with early-stage PD who had no clinically observed postural symptoms. Not applicable. Dual-task change (DTC; percent change between single-task and dual-task performance) of posture error, posture approximate entropy (ApEn), force error, and reaction time (RT). Positive DTC values indicate higher postural error, posture ApEn, force error, and force RT during dual-task conditions compared with single-task conditions. Compared with the posture-first strategy, the posture-second strategy was associated with smaller DTC of posture error and force error, and greater DTC of posture ApEn. In contrast, greater DTC of force RT was observed under the posture-second strategy. Contrary to typical recommendations, our results suggest that the posture-second strategy may be an effective dual-task strategy in patients with early-stage PD who have no clinically observed postural symptoms in order to reduce the negative effect of dual tasking on performance and facilitate postural automaticity. Copyright © 2018 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Single-stage repair of rectoperineal and rectovestibular fistulae can be safely delayed beyond the neonatal period.

PubMed

Short, Scott S; Bucher, Brian T; Barnhart, Douglas C; Van Der Watt, Nadia; Zobell, Sarah; Allen, Ashley; Rollins, Michael D

2018-02-12

We sought to examine the short-term outcomes following single-stage repair of rectoperineal and rectovestibular fistulae in infants and identify risk factors for wound complication. Patients with a rectoperineal or rectovestibular fistula treated with a single-stage repair beyond the neonatal period (>30days of age) at a pediatric colorectal center (2011-2016) were reviewed. 36 patients with a rectoperineal and 7 patients with a rectovestibular fistula were repaired using the Posterior Sagittal Anorectoplasty (PSARP) approach. Median follow-up was 31months. The median age and weight at the time of repair were 166days and 6.5kg. Four patients (11%) suffered a wound complication (3 rectoperineal, 1 rectovestibular). Two required a diverting colostomy to allow wound healing. Two patients suffered skin separation managed with local wound care. All 4 patients experienced satisfactory wound healing without anoplasty stricture. Two different patients developed a stricture of the neo-anus. Age and weight at time of repair, gender, and presence of a genitourinary anomaly were not associated with wound complications. Delayed single-stage repair of rectoperineal and rectovestibular fistulae can be performed safely in infants beyond the newborn period. With attentive treatment, satisfactory healing can be anticipated if a wound complication is encountered. Retrospective Comparative Study, Level III. Copyright © 2018. Published by Elsevier Inc.

Hypersonic airbreathing vehicle visions and enhancing technologies

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

Hunt, J.L.; Lockwood, M.K.; Petley, D.H.

1997-01-01

This paper addresses the visions for hypersonic airbreathing vehicles and the advanced technologies that forge and enhance the designs. The matrix includes space access vehicles (single-stage-to-orbit (SSTO), two-stage-to-orbit (2STO) and three-stage-to-orbit (3STO)) and endoatmospheric vehicles (airplanes{emdash}missiles are omitted). The characteristics, the performance potential, the technologies and the synergies will be discussed. A common design constraint is that all vehicles (space access and endoatmospheric) have enclosed payload bays. {copyright} {ital 1997 American Institute of Physics.}

Northrop Grumman HEC flight coaxial cryocoolers performance

NASA Astrophysics Data System (ADS)

Nguyen, T.; Russo, J.; Basel, G.; Chi, D.; Abelson, L.

2018-05-01

The Northrop Grumman Aerospace Systems (NGAS) has expanded the cryocooler product line to include a single stage High Efficiency Cryocooler (HEC) cooler with a coaxial pulse tube cold head that operates at temperatures down to 45K. The HEC coaxial pulse tube cooler has been adopted by several customers, and has completed acceptance testing to meet program flight requirements. The NGAS TRL 9 HEC is a pulse tube cryocooler with a flexure bearing compressor which has been delivered for a number of flight payloads that are currently operating in space. To date, NGAS has delivered space cryocoolers in several configurations including single stage with a linear cold head and two stage with both linear and coaxial cold heads. The new HEC coaxial cooler uses the same TRL9 HEC compressor with a passive pulse tube cold head, to maintain the flight heritage of the HEC linear cooler. In this paper, we present the flight acceptance test data of the HEC coaxial cryocooler, which includes thermal performance, launch vibration and thermal cycling. The HEC coaxial cooler has demonstrated excellent performance in family with the flight qualified HEC linear cooler. The HEC coaxial cooler provides users with additional flexibility in selecting the cold head configuration to meet their particular applications.

A new technique for high performance tandem time-of- flight mass spectrometry

NASA Astrophysics Data System (ADS)

Katz, Daniel Louis

2001-08-01

The main result of this written dissertation is a mathematical solution to the problem of multiplex recording for high performance tandem time-of-flight mass spectrometry. The prescription is to use a time-lag accelerator in the second stage to match the ion optical properties of the decay fragments to the requirements of the electrostatic ion mirror. With this technique the ion mirror is able to focus the full mass range of fragment ions at a single voltage setting, permitting acquisition of the entire mass spectrum from a single ionization event. This work was performed in support of a joint project carried out by researchers at Oregon State University and The University of Uppsala, Sweden, to design, build and test a tandem instrument featuring precision selection of the precursor species in the first stage of the spectrometer, a means of fragmenting the precursor species, and multiplex recording of the resulting fragment spectrum in the second stage. A patent application has been filed on the complete instrument with the United States Patent Office, a copy of which has been included as an appendix, and a prototype of that instrument has been constructed and awaits testing at Oregon State University.

Multi-stage decoding of multi-level modulation codes

NASA Technical Reports Server (NTRS)

Lin, Shu; Kasami, Tadao; Costello, Daniel J., Jr.

1991-01-01

Various types of multi-stage decoding for multi-level modulation codes are investigated. It is shown that if the component codes of a multi-level modulation code and types of decoding at various stages are chosen properly, high spectral efficiency and large coding gain can be achieved with reduced decoding complexity. Particularly, it is shown that the difference in performance between the suboptimum multi-stage soft-decision maximum likelihood decoding of a modulation code and the single-stage optimum soft-decision decoding of the code is very small, only a fraction of dB loss in signal to noise ratio at a bit error rate (BER) of 10(exp -6).

Concerted evolution of life stage performances signals recent selection on yeast nitrogen use.

PubMed

Ibstedt, Sebastian; Stenberg, Simon; Bagés, Sara; Gjuvsland, Arne B; Salinas, Francisco; Kourtchenko, Olga; Samy, Jeevan K A; Blomberg, Anders; Omholt, Stig W; Liti, Gianni; Beltran, Gemma; Warringer, Jonas

2015-01-01

Exposing natural selection driving phenotypic and genotypic adaptive differentiation is an extraordinary challenge. Given that an organism's life stages are exposed to the same environmental variations, we reasoned that fitness components, such as the lag, rate, and efficiency of growth, directly reflecting performance in these life stages, should often be selected in concert. We therefore conjectured that correlations between fitness components over natural isolates, in a particular environmental context, would constitute a robust signal of recent selection. Critically, this test for selection requires fitness components to be determined by different genetic loci. To explore our conjecture, we exhaustively evaluated the lag, rate, and efficiency of asexual population growth of natural isolates of the model yeast Saccharomyces cerevisiae in a large variety of nitrogen-limited environments. Overall, fitness components were well correlated under nitrogen restriction. Yeast isolates were further crossed in all pairwise combinations and coinheritance of each fitness component and genetic markers were traced. Trait variations tended to map to quantitative trait loci (QTL) that were private to a single fitness component. We further traced QTLs down to single-nucleotide resolution and uncovered loss-of-function mutations in RIM15, PUT4, DAL1, and DAL4 as the genetic basis for nitrogen source use variations. Effects of SNPs were unique for a single fitness component, strongly arguing against pleiotropy between lag, rate, and efficiency of reproduction under nitrogen restriction. The strong correlations between life stage performances that cannot be explained by pleiotropy compellingly support adaptive differentiation of yeast nitrogen source use and suggest a generic approach for detecting selection. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Effects of Hot Streak Shape on Rotor Heating in a High-Subsonic Single-Stage Turbine

NASA Technical Reports Server (NTRS)

Dorney, Daniel J.; Gundy-Burlet, Karen L.; Norvig, Peter (Technical Monitor)

1999-01-01

Experimental data have shown that combustor temperature non-uniformities can lead to the excessive heating of first-stage rotor blades in turbines. This heating of the rotor blades can lead to thermal fatigue and degrade turbine performance. The results of recent studies have shown that variations in the circumferential location (clocking) of the hot streak relative to the first-stage vane airfoils can be used to minimize the adverse effects of the hot streak. The effects of the hot streak/airfoil count ratio on the heating patterns of turbine airfoils have also been evaluated. In the present investigation, three-dimensional unsteady Navier-Stokes simulations have been performed for a single-stage high-pressure turbine operating in high subsonic flow. In addition to a simulation of the baseline turbine, simulations have been performed for circular and elliptical hot streaks of varying sizes in an effort to represent different combustor designs. The predicted results for the baseline simulation show good agreement with the available experimental data. The results of the hot streak simulations indicate: that a) elliptical hot streaks mix more rapidly than circular hot streaks, b) for small hot streak surface area the average rotor temperature is not a strong function of hot streak temperature ratio or shape, and c) hot streaks with larger surface area interact with the secondary flows at the rotor hub endwall, generating an additional high temperature region.

Advanced Launch Vehicle Upper Stages Using Liquid Propulsion and Metallized Propellants

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan A.

1990-01-01

Metallized propellants are liquid propellants with a metal additive suspended in a gelled fuel or oxidizer. Typically, aluminum (Al) particles are the metal additive. These propellants provide increase in the density and/or the specific impulse of the propulsion system. Using metallized propellant for volume-and mass-constrained upper stages can deliver modest increases in performance for low earth orbit to geosynchronous earth orbit (LEO-GEO) and other earth orbital transfer missions. Metallized propellants, however, can enable very fast planetary missions with a single-stage upper stage system. Trade studies comparing metallized propellant stage performance with non-metallized upper stages and the Inertial Upper Stage (IUS) are presented. These upper stages are both one- and two-stage vehicles that provide the added energy to send payloads to altitudes and onto trajectories that are unattainable with only the launch vehicle. The stage designs are controlled by the volume and the mass constraints of the Space Transportation System (STS) and Space Transportation System-Cargo (STS-C) launch vehicles. The influences of the density and specific impulse increases enabled by metallized propellants are examined for a variety of different stage and propellant combinations.

Assessment of Stage 35 With APNASA

NASA Technical Reports Server (NTRS)

Celestina, Mark L.; Mulac, Richard

2009-01-01

An assessment of APNASA was conducted at NASA Glenn Research Center under the Fundamental Aeronautics Program to determine their predictive capabilities. The geometry selected for this study was Stage 35 which is a single stage transonic compressor. A speedline at 100% speed was generated and compared to experimental data at 100% speed for two turbulence models. Performance of the stage at 100% speed and profiles of several key aerodynamic parameters are compared to the survey data downstream of the stator in this report. In addition, hub leakage was modeled and compared to solutions without leakage and the available experimental data.

Single-stage experimental evaluation of compressor blading with slots and vortex generators, part 5

NASA Technical Reports Server (NTRS)

Brent, J. A.

1972-01-01

An experimental investigation was conducted to determine the extent that slots and vortex generators can increase the efficiency and stable operating range of highly loaded compressor stages. With slots in the rotor and stator, the stage performance both with and without vortex generators was inferior to that achieved with the unslotted blading. However, with vortex generators, stator slots, and an unslotted rotor, the stable operating range increased 25% and the stage peak efficiency increased 2.1% over the values achieved with the unslotted rotor and stator without vortex generators, at design equivalent rotor speed.

Figures of merit for microwave photonic phase shifters based on semiconductor optical amplifiers.

PubMed

Sancho, Juan; Lloret, Juan; Gasulla, Ivana; Sales, Salvador; Capmany, José

2012-05-07

We theoretically and experimentally compare the performance of two fully tunable phase shifter structures based on semiconductor optical amplifiers (SOA) by means of several figures of merit common to microwave photonic systems. A single SOA stage followed by a tailored notch filter is compared with a cascaded implementation comprising three SOA-based phase shifter stages. Attention is focused on the assessment of the RF net gain, noise figure and nonlinear distortion. Recommendations on the performance optimization of this sort of approaches are detailed.

Lunar lander and return propulsion system trade study

NASA Technical Reports Server (NTRS)

Hurlbert, Eric A.; Moreland, Robert; Sanders, Gerald B.; Robertson, Edward A.; Amidei, David; Mulholland, John

1993-01-01

This trade study was initiated at NASA/JSC in May 1992 to develop and evaluate main propulsion system alternatives to the reference First Lunar Outpost (FLO) lander and return-stage transportation system concept. Thirteen alternative configurations were developed to explore the impacts of various combinations of return stage propellants, using either pressure or pump-fed propulsion systems and various staging options. Besides two-stage vehicle concepts, the merits of single-stage and stage-and-a-half options were also assessed in combination with high-performance liquid oxygen and liquid hydrogen propellants. Configurations using an integrated modular cryogenic engine were developed to assess potential improvements in packaging efficiency, mass performance, and system reliability compared to non-modular cryogenic designs. The selection process to evaluate the various designs was the analytic hierarchy process. The trade study showed that a pressure-fed MMH/N2O4 return stage and RL10-based lander stage is the best option for a 1999 launch. While results of this study are tailored to FLO needs, the design date, criteria, and selection methodology are applicable to the design of other crewed lunar landing and return vehicles.

Raytheon advanced pulse-tube cryocoolers

NASA Astrophysics Data System (ADS)

Conrad, Ted; Yates, Ryan; Kuo, Daniel; Schaefer, Brian; Arnoult, Matt

2016-05-01

Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Recently, Raytheon has developed an advanced regenerator technology capable of operating efficiently at high frequencies and outperforming traditional screen regenerators. The Raytheon Advanced Miniature (RAM-100) cryocooler, a flight packaged, high frequency, single stage pulse tube cooler with an integrated surge volume and inertance tube, has been designed for use with this regenerator. Design details and experimentally measured performance of two iterations of the RAM cryocooler are presented in this paper.

A comprehensive method for preliminary design optimization of axial gas turbine stages. II - Code verification

NASA Technical Reports Server (NTRS)

Jenkins, R. M.

1983-01-01

The present effort represents an extension of previous work wherein a calculation model for performing rapid pitchline optimization of axial gas turbine geometry, including blade profiles, is developed. The model requires no specification of geometric constraints. Output includes aerodynamic performance (adiabatic efficiency), hub-tip flow-path geometry, blade chords, and estimates of blade shape. Presented herein is a verification of the aerodynamic performance portion of the model, whereby detailed turbine test-rig data, including rig geometry, is input to the model to determine whether tested performance can be predicted. An array of seven (7) NASA single-stage axial gas turbine configurations is investigated, ranging in size from 0.6 kg/s to 63.8 kg/s mass flow and in specific work output from 153 J/g to 558 J/g at design (hot) conditions; stage loading factor ranges from 1.15 to 4.66.

CUDAMPF: a multi-tiered parallel framework for accelerating protein sequence search in HMMER on CUDA-enabled GPU.

PubMed

Jiang, Hanyu; Ganesan, Narayan

2016-02-27

HMMER software suite is widely used for analysis of homologous protein and nucleotide sequences with high sensitivity. The latest version of hmmsearch in HMMER 3.x, utilizes heuristic-pipeline which consists of MSV/SSV (Multiple/Single ungapped Segment Viterbi) stage, P7Viterbi stage and the Forward scoring stage to accelerate homology detection. Since the latest version is highly optimized for performance on modern multi-core CPUs with SSE capabilities, only a few acceleration attempts report speedup. However, the most compute intensive tasks within the pipeline (viz., MSV/SSV and P7Viterbi stages) still stand to benefit from the computational capabilities of massively parallel processors. A Multi-Tiered Parallel Framework (CUDAMPF) implemented on CUDA-enabled GPUs presented here, offers a finer-grained parallelism for MSV/SSV and Viterbi algorithms. We couple SIMT (Single Instruction Multiple Threads) mechanism with SIMD (Single Instructions Multiple Data) video instructions with warp-synchronism to achieve high-throughput processing and eliminate thread idling. We also propose a hardware-aware optimal allocation scheme of scarce resources like on-chip memory and caches in order to boost performance and scalability of CUDAMPF. In addition, runtime compilation via NVRTC available with CUDA 7.0 is incorporated into the presented framework that not only helps unroll innermost loop to yield upto 2 to 3-fold speedup than static compilation but also enables dynamic loading and switching of kernels depending on the query model size, in order to achieve optimal performance. CUDAMPF is designed as a hardware-aware parallel framework for accelerating computational hotspots within the hmmsearch pipeline as well as other sequence alignment applications. It achieves significant speedup by exploiting hierarchical parallelism on single GPU and takes full advantage of limited resources based on their own performance features. In addition to exceeding performance of other acceleration attempts, comprehensive evaluations against high-end CPUs (Intel i5, i7 and Xeon) shows that CUDAMPF yields upto 440 GCUPS for SSV, 277 GCUPS for MSV and 14.3 GCUPS for P7Viterbi all with 100 % accuracy, which translates to a maximum speedup of 37.5, 23.1 and 11.6-fold for MSV, SSV and P7Viterbi respectively. The source code is available at https://github.com/Super-Hippo/CUDAMPF.

Design of single piece sabot for a single stage gas gun

NASA Astrophysics Data System (ADS)

Vemparala, Vignesh; Mathew, Arun Tom; Rao Koka, Tirumala

2017-11-01

Single piece sabot is a vital part in single stage gas guns for impact testing in aerospace industries. Depending on the type of projectile used the design of sabot varies to accommodate the testing equipment. The velocity of the projectile exiting the barrel is dependent on the material and shape of the sabot used. The material selected for the design of sabot is rigid polyurethane foam, due to their low elastic modulus and low density. Two samples of rigid PU foam is taken and tests are performed to get their exact material properties. These properties are incorporated in numerical simulation to determine the best fit for practical use. Since the PU foams has a wide range of porosity which plays a prominent role in deciding the exit velocity and accuracy of the projectile coming out of the barrel. By optimisation, to the best suitable material sample can be determined.

Optimized design and performance of a shared pump single clad 2 μm TDFA

NASA Astrophysics Data System (ADS)

Tench, Robert E.; Romano, Clément; Delavaux, Jean-Marc

2018-05-01

We report the design, experimental performance, and simulation of a single stage, co- and counter-pumped Tm-doped fiber amplifier (TDFA) in the 2 μm signal wavelength band with an optimized 1567 nm shared pump source. We investigate the dependence of output power, gain, and efficiency on pump coupling ratio and signal wavelength. Small signal gains of >50 dB, an output power of 2 W, and small signal noise figures of <3.5 dB are demonstrated. Simulations of TDFA performance agree well with the experimental data. We also discuss performance tradeoffs with respect to amplifier topology for this simple and efficient TDFA.

Identifying subgroups of patients using latent class analysis: should we use a single-stage or a two-stage approach? A methodological study using a cohort of patients with low back pain.

PubMed

Nielsen, Anne Molgaard; Kent, Peter; Hestbaek, Lise; Vach, Werner; Kongsted, Alice

2017-02-01

Heterogeneity in patients with low back pain (LBP) is well recognised and different approaches to subgrouping have been proposed. Latent Class Analysis (LCA) is a statistical technique that is increasingly being used to identify subgroups based on patient characteristics. However, as LBP is a complex multi-domain condition, the optimal approach when using LCA is unknown. Therefore, this paper describes the exploration of two approaches to LCA that may help improve the identification of clinically relevant and interpretable LBP subgroups. From 928 LBP patients consulting a chiropractor, baseline data were used as input to the statistical subgrouping. In a single-stage LCA, all variables were modelled simultaneously to identify patient subgroups. In a two-stage LCA, we used the latent class membership from our previously published LCA within each of six domains of health (activity, contextual factors, pain, participation, physical impairment and psychology) (first stage) as the variables entered into the second stage of the two-stage LCA to identify patient subgroups. The description of the results of the single-stage and two-stage LCA was based on a combination of statistical performance measures, qualitative evaluation of clinical interpretability (face validity) and a subgroup membership comparison. For the single-stage LCA, a model solution with seven patient subgroups was preferred, and for the two-stage LCA, a nine patient subgroup model. Both approaches identified similar, but not identical, patient subgroups characterised by (i) mild intermittent LBP, (ii) recent severe LBP and activity limitations, (iii) very recent severe LBP with both activity and participation limitations, (iv) work-related LBP, (v) LBP and several negative consequences and (vi) LBP with nerve root involvement. Both approaches identified clinically interpretable patient subgroups. The potential importance of these subgroups needs to be investigated by exploring whether they can be identified in other cohorts and by examining their possible association with patient outcomes. This may inform the selection of a preferred LCA approach.

Propulsion requirements for reusable single-stage-to-orbit rocket vehicles

NASA Astrophysics Data System (ADS)

Stanley, Douglas O.; Engelund, Walter C.; Lepsch, Roger

1994-05-01

The conceptual design of a single-stage-to-orbit (SSTO) vehicle using a wide variety of evolutionary technologies has recently been completed as a part of NASA's Advanced Manned Launch System (AMLS) study. The employment of new propulsion system technologies is critical to the design of a reasonably sized, operationally efficient SSTO vehicle. This paper presents the propulsion system requirements identified for this near-term AMLS SSTO vehicle. Sensitivities of the vehicle to changes in specific impulse and sea-level thrust-to-weight ratio are examined. The results of a variety of vehicle/propulsion system trades performed on the near-term AMLS SSTO vehicle are also presented.

Small, high-pressure, liquid oxygen turbopump

NASA Technical Reports Server (NTRS)

Csomor, A.

1978-01-01

A small, high-pressure, LOX turbopump was designed, fabricated, and tested. The pump was of a single-stage, centrifugal type; power to the pump was supplied by a single-stage, partial-admission, axial-impulse turbine. Design conditions included an operating speed of 7330 rad/sec (70,000 rpm) pump discharge pressure of 2977 N/sq cm (4318 psia), and a pump flowrate of 16.4 kg/s (36.21 lb/sec). The turbine was propelled by LOX/LH2 combustion products at 1041 K (1874 R) inlet temperature, and at a design pressure ratio of 1.424. Test data obtained with the turbopump are presented and mechanical performance is discussed.

Analytical design of an advanced radial turbine. [automobile engines

NASA Technical Reports Server (NTRS)

Large, G. D.; Finger, D. G.; Linder, C. G.

1981-01-01

The aerodynamic and mechanical potential of a single stage ceramic radial inflow turbine was evaluated for a high temperature single stage automotive engine. The aerodynamic analysis utilizes a turbine system optimization technique to evaluate both radial and nonradial rotor blading. Selected turbine rotor configurations were evaluated mechanically with three dimensional finite element techniques. Results indicate that exceptionally high rotor tip speeds (2300 ft/sec) and performance potential are feasible with radial bladed rotors if the projected ceramic material properties are realized. Nonradial rotors reduced tip speed requirements (at constant turbine efficiency) but resulted in a lower cumulative probability of success due to higher blade and disk stresses.

An integrated approach to patient-specific predictive modeling for single ventricle heart palliation.

PubMed

Corsini, Chiara; Baker, Catriona; Kung, Ethan; Schievano, Silvia; Arbia, Gregory; Baretta, Alessia; Biglino, Giovanni; Migliavacca, Francesco; Dubini, Gabriele; Pennati, Giancarlo; Marsden, Alison; Vignon-Clementel, Irene; Taylor, Andrew; Hsia, Tain-Yen; Dorfman, Adam

2014-01-01

In patients with congenital heart disease and a single ventricle (SV), ventricular support of the circulation is inadequate, and staged palliative surgery (usually 3 stages) is needed for treatment. In the various palliative surgical stages individual differences in the circulation are important and patient-specific surgical planning is ideal. In this study, an integrated approach between clinicians and engineers has been developed, based on patient-specific multi-scale models, and is here applied to predict stage 2 surgical outcomes. This approach involves four distinct steps: (1) collection of pre-operative clinical data from a patient presenting for SV palliation, (2) construction of the pre-operative model, (3) creation of feasible virtual surgical options which couple a three-dimensional model of the surgical anatomy with a lumped parameter model (LPM) of the remainder of the circulation and (4) performance of post-operative simulations to aid clinical decision making. The pre-operative model is described, agreeing well with clinical flow tracings and mean pressures. Two surgical options (bi-directional Glenn and hemi-Fontan operations) are virtually performed and coupled to the pre-operative LPM, with the hemodynamics of both options reported. Results are validated against postoperative clinical data. Ultimately, this work represents the first patient-specific predictive modeling of stage 2 palliation using virtual surgery and closed-loop multi-scale modeling.

Multi-stage versus single-stage inflation and deflation cycle for alternating low pressure air mattresses to prevent pressure ulcers in hospitalised patients: a randomised-controlled clinical trial.

PubMed

Demarré, L; Beeckman, D; Vanderwee, K; Defloor, T; Grypdonck, M; Verhaeghe, S

2012-04-01

The duration and the amount of pressure and shear must be reduced in order to minimize the risk of pressure ulcer development. Alternating low pressure air mattresses with multi-stage inflation and deflation cycle of the air cells have been developed to relieve pressure by sequentially inflating and deflating the air cells. Evidence about the effectiveness of this type of mattress in clinical practice is lacking. This study aimed to compare the effectiveness of an alternating low pressure air mattress that has a standard single-stage inflation and deflation cycle of the air cells with an alternating low pressure air mattress with multi-stage inflation and deflation cycle of the air cells. A randomised controlled trial was performed in a convenience sample of 25 wards in five hospitals in Belgium. In total, 610 patients were included and randomly assigned to the experimental group (n=298) or the control group (n=312). In the experimental group, patients were allocated to an alternating low pressure air mattress with multi-stage inflation and deflation cycle of the air cells. In the control group, patients were allocated to an alternating low pressure air mattress with a standard single-stage inflation and deflation cycle of the air cells. The outcome was defined as cumulative pressure ulcer incidence (Grade II-IV). An intention-to-treat analysis was performed. There was no significant difference in cumulative pressure ulcer incidence (Grade II-IV) between both groups (Exp.=5.7%, Contr.=5.8%, p=0.97). When patients developed a pressure ulcer, the median time was 5.0 days in the experimental group (IQR=3.0-8.5) and 8.0 days in the control group (IQR=3.0-8.5) (Mann-Whitney U-test=113, p=0.182). The probability to remain pressure ulcer free during the observation period in this trial did not differ significantly between the experimental group and the control group (log-rank χ(2)=0.013, df=1, p=0.911). An alternating low pressure air mattress with multi-stage inflation and deflation of the air cells does not result in a significantly lower pressure ulcer incidence compared to an alternating low pressure air mattress with a standard single-stage inflation and deflation cycle of the air cells. Both alternating mattress types are equally effective to prevent pressure ulcer development. © 2011 Elsevier Ltd. All rights reserved.

Anaerobic digestion of municipal solid waste composed of food waste, wastepaper, and plastic in a single-stage system: performance and microbial community structure characterization.

PubMed

Wan, Shungang; Sun, Lei; Douieb, Yaniv; Sun, Jian; Luo, Wensui

2013-10-01

The performance of municipal organic solid waste anaerobic digestion was investigated using a single-stage bioreactor, and the microbial community structures were characterized during the digestion. The results showed that the biogas and methane production rates were 592.4 and 370.1L/kg with volatile solid added at the ratio of 2:1:1 for food waste, wastepaper, and plastic based on dry weight. The methane volume concentration fluctuated between 44.3% and 75.4% at steady stage. Acetic acid, propionic acid, and butyric acid were the major volatile fatty acids produced during the digestion process. The anaerobic process was not inhibited by the accumulation of ammonia and free ammonia. The bacterial community was found to consist of at least 21 bands of bacteria and 12 bands of archaea at the steady state. All of the results indicated that the mixture of food waste, wastepaper, and plastic could be efficiently co-digested using the anaerobic digestion system. Copyright © 2013 Elsevier Ltd. All rights reserved.

Does cemented or cementless single-stage exchange arthroplasty of chronic periprosthetic hip infections provide similar infection rates to a two-stage? A systematic review.

PubMed

George, D A; Logoluso, N; Castellini, G; Gianola, S; Scarponi, S; Haddad, F S; Drago, L; Romano, C L

2016-10-10

The best surgical modality for treating chronic periprosthetic hip infections remains controversial, with a lack of randomised controlled studies. The aim of this systematic review is to compare the infection recurrence rate after a single-stage versus a two-stage exchange arthroplasty, and the rate of cemented versus cementless single-stage exchange arthroplasty for chronic periprosthetic hip infections. We searched for eligible studies published up to December 2015. Full text or abstract in English were reviewed. We included studies reporting the infection recurrence rate as the outcome of interest following single- or two-stage exchange arthroplasty, or both, with a minimum follow-up of 12 months. Two reviewers independently abstracted data and appraised quality assessment. After study selection, 90 observational studies were included. The majority of studies were focused on a two-stage hip exchange arthroplasty (65 %), 18 % on a single-stage exchange, and only a 17 % were comparative studies. There was no statistically significant difference between a single-stage versus a two-stage exchange in terms of recurrence of infection in controlled studies (pooled odds ratio of 1.37 [95 % CI = 0.68-2.74, I 2  = 45.5 %]). Similarly, the recurrence infection rate in cementless versus cemented single-stage hip exchanges failed to demonstrate a significant difference, due to the substantial heterogeneity among the studies. Despite the methodological limitations and the heterogeneity between single cohorts studies, if we considered only the available controlled studies no superiority was demonstrated between a single- and two-stage exchange at a minimum of 12 months follow-up. The overalapping of confidence intervals related to single-stage cementless and cemented hip exchanges, showed no superiority of either technique.

Performance comparison of single-stage mixed-refrigerant Joule-Thomson cycle and reverse Brayton cycle for cooling 80 to 120 K temperature-distributed heat loads

NASA Astrophysics Data System (ADS)

Wang, H. C.; Chen, G. F.; Gong, M. Q.; Li, X.

2017-12-01

Thermodynamic performance comparison of single-stage mixed-refrigerant Joule-Thomson cycle (MJTR) and pure refrigerant reverse Brayton cycle (RBC) for cooling 80 to 120 K temperature-distributed heat loads was conducted in this paper. Nitrogen under various liquefaction pressures was employed as the heat load. The research was conducted under nonideal conditions by exergy analysis methods. Exergy efficiency and volumetric cooling capacity are two main evaluation parameters. Exergy loss distribution in each process of refrigeration cycle was also investigated. The exergy efficiency and volumetric cooling capacity of MJTR were obviously superior to RBC in 90 to 120 K temperature zone, but still inferior to RBC at 80 K. The performance degradation of MJTR was caused by two main reasons: The high fraction of neon resulted in large entropy generation and exergy loss in throttling process. Larger duty and WLMTD lead to larger exergy losses in recuperator.

A Robust High-Performance GPS L1 Receiver with Single-stage Quadrature Redio-Frequency Circuit

NASA Astrophysics Data System (ADS)

Liu, Jianghua; Xu, Weilin; Wan, Qinq; Liu, Tianci

2018-03-01

A low power current reuse single-stage quadrature raido-frequency part (SQRF) is proposed for GPS L1 receiver in 180nm CMOS process. The proposed circuit consists of LNA, Mixer, QVCO, is called the QLMV cell. A two blocks stacked topology is adopted in this design. The parallel QVCO and mixer placed on the top forms the upper stacked block, and the LNA placed on the bottom forms the other stacked block. The two blocks share the current and achieve low power performance. To improve the stability, a float current source is proposed. The float current isolated the local oscillation signal and the input RF signal, which bring the whole circuit robust high-performance. The result shows conversion gain is 34 dB, noise figure is three dB, the phase noise is -110 dBc/Hz at 1MHz and IIP3 is -20 dBm. The proposed circuit dissipated 1.7mW with 1 V supply voltage.

Single stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 4: Data and performance for stage B

NASA Technical Reports Server (NTRS)

Brent, J. A.; Cheatham, J. G.

1973-01-01

Stage B, composed of tandem-airfoil rotor B and stator B, was tested with uniform inlet flow and with hub radial, tip radial and 90 degree one-per-revolution circumferential distortion of the inlet flow as part of an overall program to evaluate the effectiveness of tandem airfoils for increasing the design point loading capability and stable operating range of rotor and stator blading. The results of this series of tests provide overall performance and blade element data for evaluating: (1) the potential of tandem blading for extending the loading limit and stable operating range of a stage representative of a middle stage of an advanced high pressure compressor, (2) the effect of loading split between the two airfoils in tandem on the performance of tandem blading, and (3) the effects of inlet flow distortion on the stage performance. The rotor had an inlet hub/tip ratio of 0.8 and a design tip velocity of 757 ft/sec. With uniform inlet flow, rotor B achieved a maximum adiabatic efficiency of 88.4% at design equivalent rotor speed and a pressure ratio of 1.31. The stage maximum adiabatic efficiency at design equivalent rotor speed with uniform inlet flow was 82.5% at a pressure ratio of 1.28. Tip radial and circumferential distortion of the inlet flow caused substantial reductions in surge margin.

Overview of the Beta II Two-Stage-To-Orbit vehicle design

NASA Technical Reports Server (NTRS)

Plencner, Robert M.

1991-01-01

A study of a near-term, low risk two-stage-to-orbit (TSTO) vehicle was undertaken. The goal of the study was to assess a fully reusable TSTO vehicle with horizontal takeoff and landing capability that could deliver 10,000 pounds to a 120 nm polar orbit. The configuration analysis was based on the Beta vehicle design. A cooperative study was performed to redesign and refine the Beta concept to meet the mission requirements. The vehicle resulting from this study was named Beta II. It has an all-airbreathing first stage and a staging Mach number of 6.5. The second stage is a conventional wing-body configuration with a single SSME.

In-Flight Study of Helmet-Mounted Symbology System Concepts in Degraded Visual Environments.

PubMed

Cheung, Bob; Craig, Gregory; Steels, Brad; Sceviour, Robert; Cosman, Vaughn; Jennings, Sion; Holst, Peter

2015-08-01

During approach and departure in rotary wing aircraft, a sudden loss of external visual reference precipitates spatial disorientation. There were 10 Royal Canadian Air Force (RCAF) Griffon pilots who participated in an in-flight investigation of a 3-dimensional conformal Helmet Display Tracking System (HDTS) and the BrownOut Symbology System (BOSS) aboard an Advanced System Research Aircraft. For each symbology system, pilots performed a two-stage departure followed by a single-stage approach. The presentation order of the two symbology systems was randomized across the pilots. Subjective measurements included situation awareness, mental effort, perceived performance, perceptual cue rating, NASA Task Load Index, and physiological response. Objective performance included aircraft speed, altitude, attitude, and distance from the landing point, control position, and control activity. Repeated measures analysis of variance and planned comparison tests for the subjective and objective responses were performed. For both maneuvers, the HDTS system afforded better situation awareness, lower workload, better perceptual cueing in attitude, horizontal and vertical translation, and lower overall workload index. During the two-stage departure, HDTS achieved less lateral drift from initial takeoff and hover, lower root mean square error (RMSE) in altitude during hover, and lower track error during the acceleration to forward flight. During the single-stage approach, HDTS achieved less error in lateral and longitudinal position offset from the landing point and lower RMSE in heading. In both maneuvers, pilots exhibited higher control activity when using HDTS, which suggested that more pertinent information was available to the pilots. Pilots preferred the HDTS system.

Single-Stage Resection of Type II Constriction Rings in Limbs on the Basis of Histologic and Magnetic Resonance Imaging Observations: A Retrospective Study of 21 Consecutive Patients.

PubMed

Jiang, Yongkang; Mao, Hailei; Yang, Xi; Zhou, Shengbo; Ni, Feng; Xu, Qiming; Wang, Bin

2016-07-01

The purpose of this study was to determine the feasibility of single-stage resection for type II congenital constriction rings by means of histologic examination of resected specimens and imaging examination of affected extremities, and to evaluate the appearance and function of the extremities after single-stage surgery. The features of the skin on the constriction rings and the subcutaneous tissues were identified through continuous sectioning, hematoxylin and eosin staining, and immunohistologic staining of specimens of type II constriction rings obtained by means of surgery. The relationship between the constriction rings and the deep main blood vessels was evaluated using magnetic resonance imaging. Single-stage resection of the constriction band, reduction of the fascial flap, and triangular flap-plasty were performed for 21 patients. The appearance, lymphedema, and movement of the extremities were compared before and after the operation. Type II constriction rings in the extremities had normal full-layer skin structures. Collagen was found deposited densely at the base of the grooves, but the normal subcutaneous tissue space remained, and the vital nerves and blood vessels were unaffected. Complete resection of the constriction rings was achieved in all 21 patients, and lymphedema subsided 2 months after the operation. No episode of recurrence was found, and limb function was not affected at 26-month follow-up. Type II congenital constriction rings in limbs possess normal subcutaneous tissue spaces. A single-stage operation, which includes complete resection of the rings, fascial flap reduction, and triangular flap-plasty, could achieve a satisfactory appearance and good function. Therapeutic, III.

Research in the design of high-performance reconfigurable systems

NASA Technical Reports Server (NTRS)

Slotnick, D. L.; Mcewan, S. D.; Spry, A. J.

1984-01-01

An initial design for the Bit Processor (BP) referred to in prior reports as the Processing Element or PE has been completed. Eight BP's, together with their supporting random-access memory, a 64 k x 9 ROM to perform addition, routing logic, and some additional logic, constitute the components of a single stage. An initial stage design is given. Stages may be combined to perform high-speed fixed or floating point arithmetic. Stages can be configured into a range of arithmetic modules that includes bit-serial one or two-dimensional arrays; one or two dimensional arrays fixed or floating point processors; and specialized uniprocessors, such as long-word arithmetic units. One to eight BP's represent a likely initial chip level. The Stage would then correspond to a first-level pluggable module. As both this project and VLSI CAD/CAM progress, however, it is expected that the chip level would migrate upward to the stage and, perhaps, ultimately the box level. The BP RAM, consisting of two banks, holds only operands and indices. Programs are at the box (high-level function) and system level. At the system level initial effort has been concentrated on specifying the tools needed to evaluate design alternatives.

Stages in Learning Motor Synergies: A View Based on the Equilibrium-Point Hypothesis

PubMed Central

Latash, Mark L.

2009-01-01

This review describes a novel view on stages in motor learning based on recent developments of the notion of synergies, the uncontrolled manifold hypothesis, and the equilibrium-point hypothesis (referent configuration) that allow to merge these notions into a single scheme of motor control. The principle of abundance and the principle of minimal final action form the foundation for analyses of natural motor actions performed by redundant sets of elements. Two main stages of motor learning are introduced corresponding to (1) discovery and strengthening of motor synergies stabilizing salient performance variable(s), and (2) their weakening when other aspects of motor performance are optimized. The first stage may be viewed as consisting of two steps, the elaboration of an adequate referent configuration trajectory and the elaboration of multi-joint (multi-muscle) synergies stabilizing the referent configuration trajectory. Both steps are expected to lead to more variance in the space of elemental variables that is compatible with a desired time profile of the salient performance variable (“good variability”). Adjusting control to other aspects of performance during the second stage (for example, esthetics, energy expenditure, time, fatigue, etc.) may lead to a drop in the “good variability”. Experimental support for the suggested scheme is reviewed. PMID:20060610

Stages in learning motor synergies: a view based on the equilibrium-point hypothesis.

PubMed

Latash, Mark L

2010-10-01

This review describes a novel view on stages in motor learning based on recent developments of the notion of synergies, the uncontrolled manifold hypothesis, and the equilibrium-point hypothesis (referent configuration) that allow to merge these notions into a single scheme of motor control. The principle of abundance and the principle of minimal final action form the foundation for analyses of natural motor actions performed by redundant sets of elements. Two main stages of motor learning are introduced corresponding to (1) discovery and strengthening of motor synergies stabilizing salient performance variable(s) and (2) their weakening when other aspects of motor performance are optimized. The first stage may be viewed as consisting of two steps, the elaboration of an adequate referent configuration trajectory and the elaboration of multi-joint (multi-muscle) synergies stabilizing the referent configuration trajectory. Both steps are expected to lead to more variance in the space of elemental variables that is compatible with a desired time profile of the salient performance variable ("good variability"). Adjusting control to other aspects of performance during the second stage (for example, esthetics, energy expenditure, time, fatigue, etc.) may lead to a drop in the "good variability". Experimental support for the suggested scheme is reviewed. Copyright © 2009 Elsevier B.V. All rights reserved.

Multi-stage decoding for multi-level block modulation codes

NASA Technical Reports Server (NTRS)

Lin, Shu; Kasami, Tadao

1991-01-01

Various types of multistage decoding for multilevel block modulation codes, in which the decoding of a component code at each stage can be either soft decision or hard decision, maximum likelihood or bounded distance are discussed. Error performance for codes is analyzed for a memoryless additive channel based on various types of multi-stage decoding, and upper bounds on the probability of an incorrect decoding are derived. It was found that, if component codes of a multi-level modulation code and types of decoding at various stages are chosen properly, high spectral efficiency and large coding gain can be achieved with reduced decoding complexity. It was found that the difference in performance between the suboptimum multi-stage soft decision maximum likelihood decoding of a modulation code and the single stage optimum decoding of the overall code is very small, only a fraction of dB loss in SNR at the probability of an incorrect decoding for a block of 10(exp -6). Multi-stage decoding of multi-level modulation codes really offers a way to achieve the best of three worlds, bandwidth efficiency, coding gain, and decoding complexity.

Core compressor exit stage study, volume 6

NASA Technical Reports Server (NTRS)

Wisler, D. C.

1981-01-01

Rear stage blading designs that have lower losses in their endwall boundary layer regions were studied. A baseline Stage A was designed as a low-speed model of stage 7 of a 10-stage compressor. Candidate rotors and stators were designed which have the potential of reducing endwall losses relative to the baseline. Rotor B uses a type of meanline in the tip region that unloads the leading edge and loads the trailing edge relative to the baseline rotor A designs. Rotor C incorporates a more skewed (hub strong) radial distribution of total pressure and smoother distribution of static pressure on the rotor tip than those of rotor B. Candidate stator B embodies twist gradients in the endwall region. Stator C embodies airfoil sections near the endwalls that have reduced trailing edge loading relative to stator A. The baseline and candidate bladings were tested using four identical stages to produce a true multistage environment. Single-stage tests were also conducted. The test data were analyzed and performances were compared. Several of the candidate configurations showed a performance improvement relative to the baseline.

[Primary, single-stage arterial switch operations at a newly-established, comprehensive congenital cardiac center performed in the neonatal age and beyond].

PubMed

Király, László; Tamás, Csaba

2015-06-21

Outcome of arterial switch operation for transposition of the great arteries with/without ventricular septal defect is a service key-performance-indicator. The aim of the authors was to assess patient characteristics and parameters in the perioperative course. In the setting of a newly-established, comprehensive tertiary-care center, primary complete repair was performed including associated anomalies, e.g. transverse arch repairs. Patients with d-transposition were grouped according to coexistence of ventricular septal defect. 118 arterial switch operations were performed between 2007 and 2014 with 96.62% survival (114/118). Ventricular septal defect and repair of associated anomalies did not yield worse outcome. Left ventricular re-training with late presentation necessitated mechanical circulatory support for 4.5±1.5 days. D-transposition is suitable for standardization of clinical algorithm and surgical technique. Quality standards contribute to excellent outcomes, minimize complications, and serve as blueprint for other neonatal open-heart procedures. Availability of mechanical circulatory support is key for single-stage left ventricular re-training beyond the neonatal period.

Rocket-Induced Magnetohydrodynamic Ejector: A Single-Stage-to-Orbit Advanced Propulsion Concept

NASA Technical Reports Server (NTRS)

Cole, John; Campbell, Jonathan; Robertson, Anthony

1995-01-01

During the atmospheric boost phase of a rocket trajectory, magnetohydrodynamic (MHD) principles can be utilized to augment the thrust by several hundred percent without the input of additional energy. The concept is an MHD implementation of a thermodynamic ejector. Some ejector history is described and some test data showing the impressive thrust augmentation capabilities of thermodynamic ejectors are provided. A momentum and energy balance is used to derive the equations to predict the MHD ejector performance. Results of these equations are compared with the test data and then applied to a specific performance example. The rocket-induced MHD ejector (RIME) engine is described and a status of the technology and availability of the engine components is provided. A top level vehicle sizing analysis is performed by scaling existing MHD designs to the required flight vehicle levels. The vehicle can achieve orbit using conservative technology. Modest improvements are suggested using recently developed technologies, such as superconducting magnets, which can improve predicted performance well beyond those expected for current single-stage-to-orbit (SSTO) designs.

Modified single-port non-intubated video-assisted thoracoscopic decortication in high-risk parapneumonic empyema patients.

PubMed

Hsiao, Chen-Hao; Chen, Ke-Cheng; Chen, Jin-Shing

2017-04-01

Parapneumonic empyema patients with coronary artery disease and reduced left ventricular ejection fraction are risky to receive surgical decortication under general anesthesia. Non-intubated video-assisted thoracoscopy surgery is successfully performed to avoid complications of general anesthesia. We performed single-port non-intubated video-assisted flexible thoracoscopy surgery in an endoscopic center. In this study, the possible role of our modified surgery to treat fibrinopurulent stage of parapneumonic empyema with high operative risks is investigated. We retrospectively reviewed fibrinopurulent stage of parapneumonic empyema patients between July 2011 and June 2014. Thirty-three patients with coronary artery disease and reduced left ventricular ejection fraction were included in this study. One group received tube thoracostomy, and the other group received single-port non-intubated video-assisted flexible thoracoscopy surgery decortication. Patient demographics, characteristics, laboratory findings, etiology, and treatment outcomes were compared. Mean age of 33 patients (24 males, 9 females) was 76.2 ± 9.7 years. Twelve patients received single-port non-intubated video-assisted flexible thoracoscopy surgery decortication, and 21 patients received tube thoracostomy. Visual analog scale scores on postoperative first hour and first day were not significantly different in two groups (p value = 0.5505 and 0.2750, respectively). Chest tube drainage days, postoperative fever subsided days, postoperative hospital days, and total length of stay were significantly short in single-port non-intubated video-assisted flexible thoracoscopy surgery decortication (p value = 0.0027, 0.0001, 0.0009, and 0.0065, respectively). Morbidities were low, and mortality was significantly low (p value = 0.0319) in single-port non-intubated video-assisted flexible thoracoscopy surgery decortication. Single-port non-intubated video-assisted flexible thoracoscopy surgery decortication may be suggested to be a method other than tube thoracostomy to deal with fibrinopurulent stage of parapneumonic empyema patients with coronary artery disease and reduced left ventricular ejection fraction.

Effect of Operating Parameters on a Dual-Stage High Velocity Oxygen Fuel Thermal Spray System

NASA Astrophysics Data System (ADS)

Khan, Mohammed N.; Shamim, Tariq

2014-08-01

High velocity oxygen fuel (HVOF) thermal spray systems are being used to apply coatings to prevent surface degradation. The coatings of temperature sensitive materials such as titanium and copper, which have very low melting points, cannot be applied using a single-stage HVOF system. Therefore, a dual-stage HVOF system has been introduced and modeled computationally. The dual-spray system provides an easy control of particle oxidation by introducing a mixing chamber. In addition to the materials being sprayed, the thermal spray coating quality depends to a large extent on flow behavior of reacting gases and the particle dynamics. The present study investigates the influence of various operating parameters on the performance of a dual-stage thermal spray gun. The objective is to develop a predictive understanding of various parameters. The gas flow field and the free jet are modeled by considering the conservation of mass, momentum, and energy with the turbulence and the equilibrium combustion sub models. The particle phase is decoupled from the gas phase due to very low particle volume fractions. The results demonstrate the advantage of a dual-stage system over a single-stage system especially for the deposition of temperature sensitive materials.

Oesophagectomy for tumours and dysplasia of the oesophagus and gastro-oesophageal junction.

PubMed

Epari, Krishna; Cade, Richard

2009-04-01

Neoadjuvant therapy, radical lymphadenectomy and treatment in high-volume centres have been proposed to improve outcomes for resectable oesophageal tumours. The aim of the present study was to review the oesophagectomy experience of a single surgeon with a moderate caseload who uses neoadjuvant therapy selectively and performs a conservative lymphadenectomy. A retrospective review of prospectively collected data was performed. The study included 125 consecutive attempted oesophageal resections performed by a single surgeon (RC) from 1993 to 2006. All patients were staged with computed tomography and also laparoscopy for lower third and junctional tumours. Endoscopic ultrasound was used in 69%. Seventy-seven per cent were adenocarcinomas. Neoadjuvant therapy was used selectively in 23%. One hundred and twenty-one resections were carried out, giving an overall resection rate of 97% with an R0 resection in 82%. In-hospital mortality was 0.8%, clinical anastomotic leak 1.7% and median length of stay 14 days. Overall median and 5-year survival were 46 months and 47%. Stage-specific 5-year survival was 100%, 71%, 41% and 21% for stages 0, I, II and III, respectively. Isolated local recurrence occurred in 8%. A moderate volume surgeon with specialist training in oesophageal resectional surgery can achieve a low mortality and anastomotic leak rate with good survival outcomes. The role for neoadjuvant therapy and radical lymphadenectomy is controversial and remains to be clearly defined. Accurate preoperative staging is essential for selection of patients for curative surgery with or without neoadjuvant therapy and for comparison of results.

A rapid method for optimization of the rocket propulsion system for single-stage-to-orbit vehicles

NASA Technical Reports Server (NTRS)

Eldred, C. H.; Gordon, S. V.

1976-01-01

A rapid analytical method for the optimization of rocket propulsion systems is presented for a vertical take-off, horizontal landing, single-stage-to-orbit launch vehicle. This method utilizes trade-offs between propulsion characteristics affecting flight performance and engine system mass. The performance results from a point-mass trajectory optimization program are combined with a linearized sizing program to establish vehicle sizing trends caused by propulsion system variations. The linearized sizing technique was developed for the class of vehicle systems studied herein. The specific examples treated are the optimization of nozzle expansion ratio and lift-off thrust-to-weight ratio to achieve either minimum gross mass or minimum dry mass. Assumed propulsion system characteristics are high chamber pressure, liquid oxygen and liquid hydrogen propellants, conventional bell nozzles, and the same fixed nozzle expansion ratio for all engines on a vehicle.

Turbulent heat transfer performance of single stage turbine

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

Amano, R.S.; Song, B.

1999-07-01

To increase the efficiency and the power of modern power plant gas turbines, designers are continually trying to raise the maximum turbine inlet temperature. Here, a numerical study based on the Navier-Stokes equations on a three-dimensional turbulent flow in a single stage turbine stator/rotor passage has been conducted and reported in this paper. The full Reynolds-stress closure model (RSM) was used for the computations and the results were also compared with the computations made by using the Launder-Sharma low-Reynolds-number {kappa}-{epsilon} model. The computational results obtained using these models were compared in order to investigate the turbulence effect in the near-wallmore » region. The set of the governing equations in a generalized curvilinear coordinate system was discretized by using the finite volume method with non-staggered grids. The numerical modeling was performed to interact between the stator and rotor blades.« less

Mechatronic design of a novel linear compliant positioning stage with large travel range and high out-of-plane payload capacity

NASA Astrophysics Data System (ADS)

Liu, Hua; Xie, Xin; Tan, Ruoyu; Zhang, Lianchao; Fan, Dapeng

2017-06-01

Most of the XY positioning stages proposed in previous studies are mainly designed by considering only a single performance indicator of the stage. As a result, the other performance indicators are relatively weak. In this study, a 2-degree-of-freedom linear compliant positioning stage (LCPS) is developed by mechatronic design to balance the interacting performance indicators and realize the desired positioning stage. The key parameters and the coupling of the structure and actuators are completely considered in the design. The LCPS consists of four voice coil motors (VCMs), which are conformally designed for compactness, and six spatial leaf spring parallelograms. These parallelograms are serially connected for a large travel range and a high out-of-plane payload capacity. The mechatronic model is established by matrix structural analysis for structural modeling and by Kirchhoff's law for the VCMs. The sensitivities of the key parameters are analyzed, and the design parameters are subsequently determined. The analytical model of the stage is confirmed by experiments. The stage has a travel range of 4.4 mm × 7.0 mm and a 0.16% area ratio of workspace to the outer dimension of the stage. The values of these performance indicators are greater than those of any existing stage reported in the literature. The closed-loop bandwidth is 9.5 Hz in both working directions. The stage can track a circular trajectory with a radius of 1.5 mm, with 40 mm error and a resolution of lower than 3 mm. The results of payload tests indicate that the stage has at least 20 kg outof- plane payload capacity.

Mathematical modeling of a continuous alcoholic fermentation process in a two-stage tower reactor cascade with flocculating yeast recycle.

PubMed

de Oliveira, Samuel Conceição; de Castro, Heizir Ferreira; Visconti, Alexandre Eliseu Stourdze; Giudici, Reinaldo

2015-03-01

Experiments of continuous alcoholic fermentation of sugarcane juice with flocculating yeast recycle were conducted in a system of two 0.22-L tower bioreactors in series, operated at a range of dilution rates (D 1 = D 2 = 0.27-0.95 h(-1)), constant recycle ratio (α = F R /F = 4.0) and a sugar concentration in the feed stream (S 0) around 150 g/L. The data obtained in these experimental conditions were used to adjust the parameters of a mathematical model previously developed for the single-stage process. This model considers each of the tower bioreactors as a perfectly mixed continuous reactor and the kinetics of cell growth and product formation takes into account the limitation by substrate and the inhibition by ethanol and biomass, as well as the substrate consumption for cellular maintenance. The model predictions agreed satisfactorily with the measurements taken in both stages of the cascade. The major differences with respect to the kinetic parameters previously estimated for a single-stage system were observed for the maximum specific growth rate, for the inhibition constants of cell growth and for the specific rate of substrate consumption for cell maintenance. Mathematical models were validated and used to simulate alternative operating conditions as well as to analyze the performance of the two-stage process against that of the single-stage process.

Staged Single Ventricle Palliation and Homozygous Sickle Cell Disease.

PubMed

Maddali, Madan Mohan; Junghare, Minakshi Sandip; Nishant, Arora Ram; Kandachar, Pranav Subbaraya; Valliattu, Johan

2016-04-01

Hypoxemia is a well-known trigger for precipitating a sickling crisis in patients with sickle cell disease. Patients undergoing staged single ventricle palliation have hypoxemia during the initial stages of the Fontan pathway. The successful completion of staged single ventricle palliation in a child with a combination of homozygous sickle cell disease and a single ventricle physiology that tolerate prolonged hypoxemia during earlier stages of Fontan pathway is described. © 2016 Wiley Periodicals, Inc.

Anaerobic-aerobic treatment of purified terephthalic acid (PTA) effluent; a techno-economic alternative to two-stage aerobic process.

PubMed

Pophali, G R; Khan, R; Dhodapkar, R S; Nandy, T; Devotta, S

2007-12-01

This paper addresses the treatment of purified terephthalic acid (PTA) effluent using anaerobic and aerobic processes. Laboratory studies were carried out on flow proportionate composite wastewater generated from the manufacturing of PTA. An activated sludge process (ASP-two stage and single stage) and an upflow anaerobic fixed film fixed bed reactor (AFFFBR) were used, individually and in combination. The performance of a full-scale ETP under existing operating conditions was also studied. Full scale ETP studies revealed that the treatment of PTA effluent using a two-stage ASP alone does not meet treated effluent quality within the prescribed Indian Standards. The biomass produced in the two stage ASP was very viscous and fluffy and the sludge volume index (SVI) was very high (200-450 ml/g). However, pretreatment of PTA effluent using an upflow AFFFBR ensured substantial reduction in BOD (63%) and COD (62%) with recovery of biogas at 1.8-1.96 l/l effluent treated at a volumetric loading rate (VLR) 4-5 kg COD/m(3) d. The methane content in the biogas varied between 55% and 60%. The pretreated effluent from the upflow AFFFBR was then treated through a single stage ASP. The biomass produced in the ASP after anaerobic treatment had very good settlability (SVI: 75-90 ml/g) as compared to the two stage ASP and the treated effluent quality with respect to BOD, COD and SS was within the prescribed Indian Standards. The alternative treatment process comprising an upflow AFFFBR and a single stage ASP ensured net power saving of 257 kW and in addition generated 442 kW of power through the AFFFBR.

Rocketdyne - J-2 Saturn V 2nd and 3rd Stage Engine. Chapter 2, Appendix D

NASA Technical Reports Server (NTRS)

Coffman, Paul

2009-01-01

The J-2 engine was unique in many respects. Technology was not nearly as well-developed in oxygen/hydrogen engines at the start of the J-2 project. As a result, it experienced a number of "teething" problems. It was used in two stages on the Saturn V vehicle in the Apollo Program, as well as on the later Skylab and Apollo/Soyuz programs. In the Apollo Program, it was used on the S-II stage, which was the second stage of the Saturn V vehicle. There were five J-2 engines at the back end of the S-II Stage. In the S-IV-B stage, it was a single engine, but that single engine had to restart. The Apollo mission called for the entire vehicle to reach orbital velocity in low Earth orbit after the first firing of the Saturn-IV-B stage and, subsequently, to fire a second time to go on to the moon. The engine had to be man-rated (worthy of transporting humans). It had to have a high thrust rate and performance associated with oxygen/hydrogen engines, although there were some compromises there. It had to gimbal for thrust vector control. It was an open-cycle gas generator engine delivering up to 230,000 pounds of thrust.

Single stage reduction and stabilization of basilar invagination after failed prior fusion surgery in children with Down's syndrome.

PubMed

Hedequist, Daniel; Bekelis, Kimon; Emans, John; Proctor, Mark R

2010-02-15

We describe an innovative single-stage reduction and stabilization technique using modern cervical instrumentation. We hypothesis modern instrumentation has made more aggressive surgical corrections possible and has reduced the need for transoral resection of the odontoid and traction reduction in children with basilar invagination. Craniocervical junction abnormalities, including atlantoaxial instability and progressive basilar invagination, are relatively common phenomenon in Down's syndrome patients, and can lead to chronic progressive neurologic deficits, catastrophic injury, and death. This patient population also can be a difficult one in which to perform successful stabilization and fusion. We reviewed the records and films on 2 children with Down's syndrome and atlantoaxial instability who had undergone prior occipital-cervical fusion and then presented with symptomatic progressive basilar invagination due to atlantoaxial displacement. In both cases, the children had progressive symptoms of spinal cord and brain stem compression. Multiple approaches for surgical correction, including preoperative traction and transoral odontoid resection, were considered, but ultimately it was elected to perform a single stage posterior operation. In both patients, we performed fusion takedown, intraoperative realignment with reduction of the basilar invagination, and stabilization using modern occipito-cervical instrumentation. In both children, excellent cranio-cervical realignment was achieved; along with successful fusion and improvement in clinical symptoms. In this article we will discuss the clinical cases and review the background of craniocervical junction abnormalities in Down's syndrome patients. We hypothesis modern instrumentation has made more aggressive surgical corrections possible and has reduced the need for transoral resection of the odontoid and traction reduction in children with basilar invagination.

Multi-stage decoding for multi-level block modulation codes

NASA Technical Reports Server (NTRS)

Lin, Shu

1991-01-01

In this paper, we investigate various types of multi-stage decoding for multi-level block modulation codes, in which the decoding of a component code at each stage can be either soft-decision or hard-decision, maximum likelihood or bounded-distance. Error performance of codes is analyzed for a memoryless additive channel based on various types of multi-stage decoding, and upper bounds on the probability of an incorrect decoding are derived. Based on our study and computation results, we find that, if component codes of a multi-level modulation code and types of decoding at various stages are chosen properly, high spectral efficiency and large coding gain can be achieved with reduced decoding complexity. In particular, we find that the difference in performance between the suboptimum multi-stage soft-decision maximum likelihood decoding of a modulation code and the single-stage optimum decoding of the overall code is very small: only a fraction of dB loss in SNR at the probability of an incorrect decoding for a block of 10(exp -6). Multi-stage decoding of multi-level modulation codes really offers a way to achieve the best of three worlds, bandwidth efficiency, coding gain, and decoding complexity.

The structure and propagation of laminar flames under autoignitive conditions

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

Krisman, Alex; Hawkes, Evatt R.; Chen, Jacqueline H.

Tmore » he laminar flame speed s l is an important reference quantity for characterising and modelling combustion. Experimental measurements of laminar flame speed require the residence time of the fuel/air mixture (τ f) to be shorter than the autoignition delay time (τ). his presents a considerable challenge for conditions where autoignition occurs rapidly, such as in compression ignition engines. As a result, experimental measurements in typical compression ignition engine conditions do not exist. Simulations of freely propagating premixed flames, where the burning velocity is found as an eigenvalue of the solution, are also not well posed in such conditions, since the mixture ahead of the flame can autoignite, leading to the so called “cold boundary problem”. In this paper, a numerical method for estimating a reference flame speed, s R, is proposed that is valid for laminar flame propagation at autoignitive conditions. wo isomer fuels are considered to test this method: ethanol, which in the considered conditions is a single-stage ignition fuel; and dimethyl ether, which has a temperature-dependent single- or two-stage ignition and a negative temperature coefficient regime for τ. Calculations are performed for the flame position in a one-dimensional computational domain with inflow-outflow boundary conditions, as a function of the inlet velocity U I and for stoichiometric fuel–air premixtures. he response of the flame position, L F, to U I shows distinct stabilisation regimes. For single-stage ignition fuels, at low U I the flame speed exceeds U I and the flame becomes attached to the inlet. Above a critical U I value, the flame detaches from the inlet and L f becomes extremely sensitive to U I until, for sufficiently high U I, the sensitivity decreases and L f corresponds to the location expected from a purely autoignition stabilised flame. he transition from the attached to the autoignition regimes has a corresponding peak dL f/dU I value which is proposed to be a unique reference flame speed s R for single-stage ignition fuels. For two-stage ignition fuels, there is an additional stable regime where a high-temperature flame propagates into a pool of combustion intermediates generated by the first stage of autoignition. his results in two peaks in dL f/dU I and therefore two reference flame speed values. he lower value corresponds to the definition of s R for single-stage ignition fuels, while the higher value exists only for two-stage ignition fuels and corresponds to a high temperature flame propagating into the first stage of autoignition and is denoted s R ' . Finally, a transport budget analysis for low- and high-temperature radical species is also performed, which confirms that the flame structures at U I = s R and U I = s R ' do indeed correspond to premixed flames (deflagrations), as opposed to spontaneous ignition fronts which do not have a unique propagation speed.« less

The structure and propagation of laminar flames under autoignitive conditions

DOE PAGES

Krisman, Alex; Hawkes, Evatt R.; Chen, Jacqueline H.

2017-11-05

Tmore » he laminar flame speed s l is an important reference quantity for characterising and modelling combustion. Experimental measurements of laminar flame speed require the residence time of the fuel/air mixture (τ f) to be shorter than the autoignition delay time (τ). his presents a considerable challenge for conditions where autoignition occurs rapidly, such as in compression ignition engines. As a result, experimental measurements in typical compression ignition engine conditions do not exist. Simulations of freely propagating premixed flames, where the burning velocity is found as an eigenvalue of the solution, are also not well posed in such conditions, since the mixture ahead of the flame can autoignite, leading to the so called “cold boundary problem”. In this paper, a numerical method for estimating a reference flame speed, s R, is proposed that is valid for laminar flame propagation at autoignitive conditions. wo isomer fuels are considered to test this method: ethanol, which in the considered conditions is a single-stage ignition fuel; and dimethyl ether, which has a temperature-dependent single- or two-stage ignition and a negative temperature coefficient regime for τ. Calculations are performed for the flame position in a one-dimensional computational domain with inflow-outflow boundary conditions, as a function of the inlet velocity U I and for stoichiometric fuel–air premixtures. he response of the flame position, L F, to U I shows distinct stabilisation regimes. For single-stage ignition fuels, at low U I the flame speed exceeds U I and the flame becomes attached to the inlet. Above a critical U I value, the flame detaches from the inlet and L f becomes extremely sensitive to U I until, for sufficiently high U I, the sensitivity decreases and L f corresponds to the location expected from a purely autoignition stabilised flame. he transition from the attached to the autoignition regimes has a corresponding peak dL f/dU I value which is proposed to be a unique reference flame speed s R for single-stage ignition fuels. For two-stage ignition fuels, there is an additional stable regime where a high-temperature flame propagates into a pool of combustion intermediates generated by the first stage of autoignition. his results in two peaks in dL f/dU I and therefore two reference flame speed values. he lower value corresponds to the definition of s R for single-stage ignition fuels, while the higher value exists only for two-stage ignition fuels and corresponds to a high temperature flame propagating into the first stage of autoignition and is denoted s R ' . Finally, a transport budget analysis for low- and high-temperature radical species is also performed, which confirms that the flame structures at U I = s R and U I = s R ' do indeed correspond to premixed flames (deflagrations), as opposed to spontaneous ignition fronts which do not have a unique propagation speed.« less

A prospective evaluation of early detection biomarkers for ovarian cancer in the European EPIC cohort

PubMed Central

Terry, Kathryn L.; Schock, Helena; Fortner, Renée T.; Hüsing, Anika; Fichorova, Raina N.; Yamamoto, Hidemi S.; Vitonis, Allison F.; Johnson, Theron; Overvad, Kim; Tjønneland, Anne; Boutron-Ruault, Marie-Christine; Mesrine, Sylvie; Severi, Gianluca; Dossus, Laure; Rinaldi, Sabina; Boeing, Heiner; Benetou, Vassiliki; Lagiou, Pagona; Trichopoulou, Antonia; Krogh, Vittorio; Kuhn, Elisabetta; Panico, Salvatore; Bueno-de-Mesquita, H. Bas; Onland-Moret, N. Charlotte; Peeters, Petra H.; Gram, Inger Torhild; Weiderpass, Elisabete; Duell, Eric J.; Sanchez, Maria-Jose; Ardanaz, Eva; Etxezarreta, Nerea; Navarro, Carmen; Idahl, Annika; Lundin, Eva; Jirström, Karin; Manjer, Jonas; Wareham, Nicholas J.; Khaw, Kay-Tee; Byrne, Karl Smith; Travis, Ruth C.; Gunter, Marc J.; Merritt, Melissa A.; Riboli, Elio; Cramer, Daniel W.; Kaaks, Rudolf

2016-01-01

Purpose About 60% of ovarian cancers are diagnosed at late stage, when 5-year survival is less than 30% in contrast to 90% for local disease. This has prompted search for early detection biomarkers. For initial testing, specimens taken months or years before ovarian cancer diagnosis are the best source of information to evaluate early detection biomarkers. Here we evaluate the most promising ovarian cancer screening biomarkers in prospectively collected samples from the European Prospective Investigation into Cancer and Nutrition study. Experimental Design We measured CA125, HE4, CA72.4 and CA15.3 in 810 invasive epithelial ovarian cancer cases and 1,939 controls. We calculated the sensitivity at 95% and 98% specificity as well as Area under the Receiver Operator Curve (C-statistic) for each marker individually and in combination. Additionally, we evaluated marker performance by stage at diagnosis and time between blood draw and diagnosis. Results We observed the best discrimination between cases and controls within six months of diagnosis for CA125 (C-statistic=0.92), then HE4 (0.84), CA72.4 (0.77), and CA15.3 (0.73). Marker performance declined with longer time between blood draw and diagnosis and for earlier staged disease. However, assessment of discriminatory ability at early stage was limited by small numbers. Combinations of markers performed modestly, but significantly better than any single marker. Conclusions CA125 remains the single best marker for the early detection of invasive epithelial ovarian cancer, but can be slightly improved by combining with other markers. Identifying novel markers for ovarian cancer will require studies including larger numbers of early stage cases. PMID:27060155

A Prospective Evaluation of Early Detection Biomarkers for Ovarian Cancer in the European EPIC Cohort.

PubMed

Terry, Kathryn L; Schock, Helena; Fortner, Renée T; Hüsing, Anika; Fichorova, Raina N; Yamamoto, Hidemi S; Vitonis, Allison F; Johnson, Theron; Overvad, Kim; Tjønneland, Anne; Boutron-Ruault, Marie-Christine; Mesrine, Sylvie; Severi, Gianluca; Dossus, Laure; Rinaldi, Sabina; Boeing, Heiner; Benetou, Vassiliki; Lagiou, Pagona; Trichopoulou, Antonia; Krogh, Vittorio; Kuhn, Elisabetta; Panico, Salvatore; Bueno-de-Mesquita, H Bas; Onland-Moret, N Charlotte; Peeters, Petra H; Gram, Inger Torhild; Weiderpass, Elisabete; Duell, Eric J; Sanchez, Maria-Jose; Ardanaz, Eva; Etxezarreta, Nerea; Navarro, Carmen; Idahl, Annika; Lundin, Eva; Jirström, Karin; Manjer, Jonas; Wareham, Nicholas J; Khaw, Kay-Tee; Byrne, Karl Smith; Travis, Ruth C; Gunter, Marc J; Merritt, Melissa A; Riboli, Elio; Cramer, Daniel W; Kaaks, Rudolf

2016-09-15

About 60% of ovarian cancers are diagnosed at late stage, when 5-year survival is less than 30% in contrast to 90% for local disease. This has prompted search for early detection biomarkers. For initial testing, specimens taken months or years before ovarian cancer diagnosis are the best source of information to evaluate early detection biomarkers. Here we evaluate the most promising ovarian cancer screening biomarkers in prospectively collected samples from the European Prospective Investigation into Cancer and Nutrition study. We measured CA125, HE4, CA72.4, and CA15.3 in 810 invasive epithelial ovarian cancer cases and 1,939 controls. We calculated the sensitivity at 95% and 98% specificity as well as area under the receiver operator curve (C-statistic) for each marker individually and in combination. In addition, we evaluated marker performance by stage at diagnosis and time between blood draw and diagnosis. We observed the best discrimination between cases and controls within 6 months of diagnosis for CA125 (C-statistic = 0.92), then HE4 (0.84), CA72.4 (0.77), and CA15.3 (0.73). Marker performance declined with longer time between blood draw and diagnosis and for earlier staged disease. However, assessment of discriminatory ability at early stage was limited by small numbers. Combinations of markers performed modestly, but significantly better than any single marker. CA125 remains the single best marker for the early detection of invasive epithelial ovarian cancer, but can be slightly improved by combining with other markers. Identifying novel markers for ovarian cancer will require studies including larger numbers of early-stage cases. Clin Cancer Res; 22(18); 4664-75. ©2016 AACRSee related commentary by Skates, p. 4542. ©2016 American Association for Cancer Research.

Performance of μ-RWELL detector vs resistivity of the resistive stage

NASA Astrophysics Data System (ADS)

Bencivenni, G.; De Oliveira, R.; Felici, G.; Gatta, M.; Morello, G.; Ochi, A.; Lener, M. Poli; Tskhadadze, E.

2018-04-01

The μ-RWELL is a compact spark-protected single amplification stage Micro-Pattern-Gaseous-Detector (MPGD). The detector amplification stage is realized with a polyimide structure, micro-patterned with a dense matrix of blind-holes, integrated into the readout structure. The anode is formed by a thin Diamond Like Carbon (DLC) resistive layer separated by an insulating glue layer from the readout strips. The introduction of the resistive layer strongly suppressing the transition from streamer to spark gives the possibility to achieve large gains (> 104), without significantly affecting the capability to be efficiently operated in high particle fluxes. In this work we present the results of a systematic study of the μ-RWELL performance as a function of the DLC resistivity. The tests have been performed either with collimated 5.9 keV X-rays or with pion and muon beams at the SPS Secondary Beamline H4 and H8 at CERN.

Two-stage urethroplasty is a better choice for proximal hypospadias with severe chordee after urethral plate transection: a single-center experience.

PubMed

Zheng, Da-Chao; Yao, Hai-Jun; Cai, Zhi-Kang; Da, Jun; Chen, Qi; Chen, Yan-Bo; Zhang, Ke; Xu, Ming-Xi; Lu, Mu-Jun; Wang, Zhong

2015-01-01

It is still debatable whether single- or two-stage urethroplasty is a more suitable technique for treating hypospadias with severe chordee after urethral plate transection. This retrospective study evaluated these two techniques. A total of 66 patients of proximal hypospadias with severe chordee were divided into two groups according to the techniques they underwent: 32 and 34 patients underwent single-stage (Duckett) or two-stage urethroplasty, respectively. Median ages at presentation were 7.5 years and 11.0 years in single-stage and two-stage repair groups, respectively. Median follow-ups were 28.5 months (20-60 months) and 35 months (18-60 months) in the single-stage and two-stage groups, respectively. The meatus of the neourethra was located at the top of the glans in all patients. No recurrence of chordee was found during follow-up, and all patients or parents were satisfied with the penile length and appearance. Complications were encountered in eight patients in both groups, with no statistically significant differences between the two techniques. The late complication rate of stricture was higher after the single-stage procedure (18.75% vs 0%). The complication rate after single-stage repairs was significantly lower in the prepubescent subgroup (10.52%) than in the postpubescent cohort (46.15%). These results indicate that the urethral plate transection effectively corrects severe chordee associated with proximal hypospadias during the intermediate follow-up period. Considering the higher rate of stricture after single-stage urethroplasty, two-stage urethroplasty is recommended for proximal hypospadias with severe chordee after urethral plate transection.

Dual-Fuel Propulsion in Single-Stage Advanced Manned Launch System Vehicle

NASA Technical Reports Server (NTRS)

Lepsch, Roger A., Jr.; Stanley, Douglas O.; Unal, Resit

1995-01-01

As part of the United States Advanced Manned Launch System study to determine a follow-on, or complement, to the Space Shuttle, a reusable single-stage-to-orbit concept utilizing dual-fuel rocket propulsion has been examined. Several dual-fuel propulsion concepts were investigated. These include: a separate-engine concept combining Russian RD-170 kerosene-fueled engines with space shuttle main engine-derivative engines: the kerosene- and hydrogen-fueled Russian RD-701 engine; and a dual-fuel, dual-expander engine. Analysis to determine vehicle weight and size characteristics was performed using conceptual-level design techniques. A response-surface methodology for multidisciplinary design was utilized to optimize the dual-fuel vehicles with respect to several important propulsion-system and vehicle design parameters, in order to achieve minimum empty weight. The tools and methods employed in the analysis process are also summarized. In comparison with a reference hydrogen- fueled single-stage vehicle, results showed that the dual-fuel vehicles were from 10 to 30% lower in empty weight for the same payload capability, with the dual-expander engine types showing the greatest potential.

Accounting for uncertainty in the historical response rate of the standard treatment in single-arm two-stage designs based on Bayesian power functions.

PubMed

Matano, Francesca; Sambucini, Valeria

2016-11-01

In phase II single-arm studies, the response rate of the experimental treatment is typically compared with a fixed target value that should ideally represent the true response rate for the standard of care therapy. Generally, this target value is estimated through previous data, but the inherent variability in the historical response rate is not taken into account. In this paper, we present a Bayesian procedure to construct single-arm two-stage designs that allows to incorporate uncertainty in the response rate of the standard treatment. In both stages, the sample size determination criterion is based on the concepts of conditional and predictive Bayesian power functions. Different kinds of prior distributions, which play different roles in the designs, are introduced, and some guidelines for their elicitation are described. Finally, some numerical results about the performance of the designs are provided and a real data example is illustrated. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

The Trailblazer Program

NASA Technical Reports Server (NTRS)

Trefney, Charles J.

1999-01-01

This paper presents the "Three Pillars of Success" for the Trailblazer Program. The topics include: 1) The "Rocket Equation" for SSTO (Single Stage To Orbit); 2) The Rocket I* Barrier; 3) Rocket-Based Combined-Cycle Engine; 4) Potential for Reusability; 5) Factors Mitigating RBCC Performance; 6) The "Trailblazer" Program; 7) Trailblazer Performance Goals; 8) Trailblazer Reference Vehicle; and 9) Trailblazer Program Architecture.

Overall and blade element performance of a 1.20-pressure-ratio fan stage with rotor blades reset -5 deg

NASA Technical Reports Server (NTRS)

Lewis, G. W., Jr.; Osborn, W. M.; Moore, R. D.

1976-01-01

A 51-cm-diam model of a fan stage for a short haul aircraft was tested in a single stage-compressor research facility. The rotor blades were set 5 deg toward the axial direction (opened) from design setting angle. Surveys of the air flow conditions ahead of the rotor, between the rotor and stator, and behind the stator were made over the stable operating range of the stage. At the design speed of 213.3 m/sec and a weight flow of 31.5 kg/sec, the stage pressure ratio and efficiency were 1.195 and 0.88, respectively. The design speed rotor peak efficiency of 0.91 occurred at the same flow rate.

Overall and blade element performance of a 1.20 pressure ratio fan stage with rotor blades reset -7 deg

NASA Technical Reports Server (NTRS)

Lewis, G. W., Jr.; Kovich, G.

1976-01-01

A 51-cm-diam model of a fan stage for short haul aircraft was tested in a single stage compressor research facility. The rotor blades were set 7 deg toward the axial direction (opened) from the design setting angle. Surveys of the air flow conditions ahead of the rotor, between the rotor and stator, and behind the stator were made over the stable operating range of the stage. At the design speed and a weight flow of 30.9 kg/sec, the stage pressure ratio and efficiency were 1.205 and 0.85, respectively. The design speed rotor peak efficiency of 0.90 occurred at a flow rate of 32.5 kg/sec.

A single-stage optical load-balanced switch for data centers.

PubMed

Huang, Qirui; Yeo, Yong-Kee; Zhou, Luying

2012-10-22

Load balancing is an attractive technique to achieve maximum throughput and optimal resource utilization in large-scale switching systems. However current electronic load-balanced switches suffer from severe problems in implementation cost, power consumption and scaling. To overcome these problems, in this paper we propose a single-stage optical load-balanced switch architecture based on an arrayed waveguide grating router (AWGR) in conjunction with fast tunable lasers. By reuse of the fast tunable lasers, the switch achieves both functions of load balancing and switching through the AWGR. With this architecture, proof-of-concept experiments have been conducted to investigate the feasibility of the optical load-balanced switch and to examine its physical performance. Compared to three-stage load-balanced switches, the reported switch needs only half of optical devices such as tunable lasers and AWGRs, which can provide a cost-effective solution for future data centers.

Downstream processing of antibodies: single-stage versus multi-stage aqueous two-phase extraction.

PubMed

Rosa, P A J; Azevedo, A M; Ferreira, I F; Sommerfeld, S; Bäcker, W; Aires-Barros, M R

2009-12-11

Single-stage and multi-stage strategies have been evaluated and compared for the purification of human antibodies using liquid-liquid extraction in aqueous two-phase systems (ATPSs) composed of polyethylene glycol 3350 (PEG 3350), dextran, and triethylene glycol diglutaric acid (TEG-COOH). The performance of single-stage extraction systems was firstly investigated by studying the effect of pH, TEG-COOH concentration and volume ratio on the partitioning of the different components of a Chinese hamster ovary (CHO) cells supernatant. It was observed that lower pH values and high TEG-COOH concentrations favoured the selective extraction of human immunoglobulin G (IgG) to the PEG-rich phase. Higher recovery yields, purities and percentage of contaminants removal were always achieved in the presence of the ligand, TEG-COOH. The extraction of IgG could be enhanced using higher volume ratios, however with a significant decrease in both purity and percentage of contaminants removal. The best single-stage extraction conditions were achieved for an ATPS containing 1.3% (w/w) TEG-COOH with a volume ratio of 2.2, which allowed the recovery of 96% of IgG in the PEG-rich phase with a final IgG concentration of 0.21mg/mL, a protein purity of 87% and a total purity of 43%. In order to enhance simultaneously both recovery yield and purity, a four stage cross-current operation was simulated and the corresponding liquid-liquid equilibrium (LLE) data determined. A predicted optimised scheme of a counter-current multi-stage aqueous two-phase extraction was hence described. IgG can be purified in the PEG-rich top phase with a final recovery yield of 95%, a final concentration of 1.04mg/mL and a protein purity of 93%, if a PEG/dextran ATPS containing 1.3% (w/w) TEG-COOH, 5 stages and volume ratio of 0.4 are used. Moreover, according to the LLE data of all CHO cells supernatant components, it was possible to observe that most of the cells supernatant contaminants can be removed during this extraction step leading to a final total purity of about 85%.

Metacarpal lengthening in children: comparison of three different techniques in 15 consecutive cases.

PubMed

Dana, C; Aurégan, J-C; Salon, A; Guéro, S; Glorion, C; Pannier, S

2016-09-22

Metacarpal lengthening is a useful procedure to address hand deficiencies in children. In this study, we aimed to compare the results of three different techniques from one consecutive clinical series of hand deficiencies. A total of 15 metacarpal lengthenings have been performed in 12 children aged from 9 to 14 years. The callotasis technique was used in seven cases, the two-stage distraction-graft technique in four cases and the single-stage lengthening in four cases. All the metacarpals healed with bone. The lengthening obtained was a mean of 13 mm (range 8-21 mm), a mean of 22 mm (range 13-32 mm) and a mean of 12 mm (range 9-15 mm), respectively, in the three different techniques. The healing index was longer for callotasis (81 days/cm) compared with the other techniques (41 days/cm and 46 days/cm, respectively). We observed one case of fracture after callotasis and one after distraction-graft. One patient underwent tenolysis of the extensor mechanism after single-stage lengthening. In conclusion, distraction graft and single-stage lengthening may be valuable alternatives to callotasis. IV; therapeutic study; multi-case series. © The Author(s) 2016.

Merits of full flow vs. conventional staged combustion cycles for reusable launch vehicle propulsion

NASA Astrophysics Data System (ADS)

Peery, Steven D.; Parsley, Randy C.

1996-03-01

This paper provides a comparison between full-flow and conventional staged combustion thermodynamic O2/H2 rocket engine cycles for Reusable Launch Vehicle, RLV, single-stage-to-orbit applications. The impact of the cycle thermodynamics, component configuration, and component operating parameters on engine performance and weight for the two approaches is presented. Both cycles were modeled with equivalent technology turbomachinery and chamber/nozzle RLV life requirements. The first order impact of cycle selection, pump exit pressure, and turbine temperature on the empty weight of an SSTO Reusable Launch Vehicle is presented.

Use of Perceive, Recall, Plan, Perform Stage Two Cognitive Task Analysis for Students with Autism and Intellectual Disability: The Impact of a Sensory Activity Schedule

ERIC Educational Resources Information Center

Mills, Caroline; Chapparo, Christine

2017-01-01

The aim of this study was to determine the impact of a classroom sensory activity schedule (SAS) on cognitive strategy use during task performance. This work studies a single-system AB research design with seven students with autism and intellectual disability. Repeated measures using the Perceive, Recall, Plan and Perform (PRPP) Cognitive Task…

A Multidisciplinary Performance Analysis of a Lifting-Body Single-Stage-to-Orbit Vehicle

NASA Technical Reports Server (NTRS)

Tartabini, Paul V.; Lepsch, Roger A.; Korte, J. J.; Wurster, Kathryn E.

2000-01-01

Lockheed Martin Skunk Works (LMSW) is currently developing a single-stage-to-orbit reusable launch vehicle called VentureStar(TM) A team at NASA Langley Research Center participated with LMSW in the screening and evaluation of a number of early VentureStar(TM) configurations. The performance analyses that supported these initial studies were conducted to assess the effect of a lifting body shape, linear aerospike engine and metallic thermal protection system (TPS) on the weight and performance of the vehicle. These performance studies were performed in a multidisciplinary fashion that indirectly linked the trajectory optimization with weight estimation and aerothermal analysis tools. This approach was necessary to develop optimized ascent and entry trajectories that met all vehicle design constraints. Significant improvements in ascent performance were achieved when the vehicle flew a lifting trajectory and varied the engine mixture ratio during flight. Also, a considerable reduction in empty weight was possible by adjusting the total oxidizer-to-fuel and liftoff thrust-to-weight ratios. However, the optimal ascent flight profile had to be altered to ensure that the vehicle could be trimmed in pitch using only the flow diverting capability of the aerospike engine. Likewise, the optimal entry trajectory had to be tailored to meet TPS heating rate and transition constraints while satisfying a crossrange requirement.

Using Saliency-Weighted Disparity Statistics for Objective Visual Comfort Assessment of Stereoscopic Images

NASA Astrophysics Data System (ADS)

Zhang, Wenlan; Luo, Ting; Jiang, Gangyi; Jiang, Qiuping; Ying, Hongwei; Lu, Jing

2016-06-01

Visual comfort assessment (VCA) for stereoscopic images is a particularly significant yet challenging task in 3D quality of experience research field. Although the subjective assessment given by human observers is known as the most reliable way to evaluate the experienced visual discomfort, it is time-consuming and non-systematic. Therefore, it is of great importance to develop objective VCA approaches that can faithfully predict the degree of visual discomfort as human beings do. In this paper, a novel two-stage objective VCA framework is proposed. The main contribution of this study is that the important visual attention mechanism of human visual system is incorporated for visual comfort-aware feature extraction. Specifically, in the first stage, we first construct an adaptive 3D visual saliency detection model to derive saliency map of a stereoscopic image, and then a set of saliency-weighted disparity statistics are computed and combined to form a single feature vector to represent a stereoscopic image in terms of visual comfort. In the second stage, a high dimensional feature vector is fused into a single visual comfort score by performing random forest algorithm. Experimental results on two benchmark databases confirm the superior performance of the proposed approach.

Single-stage surgery for symptomatic small-angle strabismus under topical anaesthesia.

PubMed

Zou, Leilei; Liu, Rui; Liu, Hong; Huang, Liwen; Liu, Yan; Wang, Aihou

2014-04-01

To report outcomes of single-stage surgery under topical anaesthesia for the treatment of small-angle strabismus. Case series. Thirteen patients, 7 males and 6 females, with a median age of 32 years (range, 20-59 years) were included. Patients with symptomatic small-angle strabismus with stable deviations of no more than 20 prism diopters (PD) in horizontal and 10 PD in vertical were consecutively recruited from the Eye and ENT Hospital of Fudan University between January 2010 and April 2012. Single-stage surgery was performed under topical anaesthesia. Outcome measures were PD, Amblyopia and Strabismus Questionnaire (ASQE) scores, and subjective reduction of symptoms. The median duration of symptoms was 40 months (range, 6-96 months). Nine patients had horizontal deviations, 3 had vertical deviations, and 1 had an exodeviation combined with a vertical deviation. All surgeries were completed without complications, and no patients experienced significant discomfort. All patients reported elimination of symptoms on postoperative day 1. Two patients required a second procedure at 1 week because of a return of symptoms. At 6-month follow-up, no patient reported recurrence of symptoms. The overall ASQE score improved from 70 preoperatively to 96 postoperatively (p = 0.001). These results suggest single-stage surgery under topical anaesthesia is an effective treatment for small-angle strabismus. A large, randomized, prospective study to confirm these findings is warranted. © 2013 Canadian Ophthalmological Society Published by Canadian Ophthalmological Society All rights reserved.

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

PubMed

Fink, Bernd; Schlumberger, Michael; Oremek, Damian

2017-08-01

The treatment of periprosthetic infections of hip arthroplasties typically involves use of either a single- or two-stage (with implantation of a temporary spacer) revision surgery. In patients with severe acetabular bone deficiencies, either already present or after component removal, spacers cannot be safely implanted. In such hips where it is impossible to use spacers and yet a two-stage revision of the prosthetic stem is recommended, we have combined a two-stage revision of the stem with a single revision of the cup. To our knowledge, this approach has not been reported before. (1) What proportion of patients treated with single-stage acetabular reconstruction as part of a two-stage revision for an infected THA remain free from infection at 2 or more years? (2) What are the Harris hip scores after the first stage and at 2 years or more after the definitive reimplantation? Between June 2009 and June 2014, we treated all patients undergoing surgical treatment for an infected THA using a single-stage acetabular revision as part of a two-stage THA exchange if the acetabular defect classification was Paprosky Types 2B, 2C, 3A, 3B, or pelvic discontinuity and a two-stage procedure was preferred for the femur. The procedure included removal of all components, joint débridement, definitive acetabular reconstruction (with a cage to bridge the defect, and a cemented socket), and a temporary cemented femoral component at the first stage; the second stage consisted of repeat joint and femoral débridement and exchange of the femoral component to a cementless device. During the period noted, 35 patients met those definitions and were treated with this approach. No patients were lost to followup before 2 years; mean followup was 42 months (range, 24-84 months). The clinical evaluation was performed with the Harris hip scores and resolution of infection was assessed by the absence of clinical signs of infection and a C-reactive protein level less than 10 mg/L. All patients were assessed before surgery, between stages, every 3 months during the first year after surgery, every 6 months during the second year postoperative, and at latest followup, and were retrospectively drawn from a longitudinally maintained institutional database. Thirty-four of 35 patients (97.2%; 95% CI, 85.4%-99.5%) appeared free of infection by criteria of Masri et al. and Zimmerli et al. at latest followup. The Harris hip score was 61 ± 13 points after the first operation and 82 ± 16 points 2 years after the second operation. This technique is a promising treatment option for periprosthetic infections of the hip in which substantial acetabular defects exclude implantation of a normal spacer and a two-stage revision of the femoral component is favored. Level IV, therapeutic study.

Stimulus encoding and feature extraction by multiple sensory neurons.

PubMed

Krahe, Rüdiger; Kreiman, Gabriel; Gabbiani, Fabrizio; Koch, Christof; Metzner, Walter

2002-03-15

Neighboring cells in topographical sensory maps may transmit similar information to the next higher level of processing. How information transmission by groups of nearby neurons compares with the performance of single cells is a very important question for understanding the functioning of the nervous system. To tackle this problem, we quantified stimulus-encoding and feature extraction performance by pairs of simultaneously recorded electrosensory pyramidal cells in the hindbrain of weakly electric fish. These cells constitute the output neurons of the first central nervous stage of electrosensory processing. Using random amplitude modulations (RAMs) of a mimic of the fish's own electric field within behaviorally relevant frequency bands, we found that pyramidal cells with overlapping receptive fields exhibit strong stimulus-induced correlations. To quantify the encoding of the RAM time course, we estimated the stimuli from simultaneously recorded spike trains and found significant improvements over single spike trains. The quality of stimulus reconstruction, however, was still inferior to the one measured for single primary sensory afferents. In an analysis of feature extraction, we found that spikes of pyramidal cell pairs coinciding within a time window of a few milliseconds performed significantly better at detecting upstrokes and downstrokes of the stimulus compared with isolated spikes and even spike bursts of single cells. Coincident spikes can thus be considered "distributed bursts." Our results suggest that stimulus encoding by primary sensory afferents is transformed into feature extraction at the next processing stage. There, stimulus-induced coincident activity can improve the extraction of behaviorally relevant features from the stimulus.

Evaluation of a low aspect ratio small axial compressor stage, volume 1

NASA Technical Reports Server (NTRS)

Sawyer, C. W., III

1977-01-01

A program was conducted to evaluate the effects of scaling, tip clearance, and IGV reset on the performance of a low aspect ratio compressor stage. Stage design was obtained by scaling an existing single stage compressor by a linear factor of 0.304. The design objective was to maintain the meanline velocity field of the base machine in the smaller size. Adjustments were made to account for predicted blockage differences and to chord lengths and airfoil edge radii to obtain reasonable blade geometries. Meanline velocity diagrams of the base stage were not maintained at the scaled size. At design speed and flowrate the scaled stage achieved a pressure ratio of 1.423, adiabatic efficiency of 0.822, and surge margin of 18.5%. The corresponding performance parameters for the base stage were 1.480, 0.872, and 25.2%, respectively. The base stage demonstrated a peak efficiency at design speed of 0.872; the scaled stage achieved a level of 0.838. When the scaled stage rotor and stator tip clearances were doubled, the stage achieved a pressure ratio of 1.413, efficiency of 0.799, and surge margin of 16.0% at the design flowrate. The peak stage efficiency at design speed was 0.825 with the increased clearance. Increased prewhirl lowered the stage pressure ratio as expected. Stage efficiency was maintained with ten degrees of increased prewhirl and then decreased substantially with ten additional degrees of reset.

Cooperative vaccinia infection demonstrated at the single-cell level using FluidFM.

PubMed

Stiefel, Philipp; Schmidt, Florian I; Dörig, Pablo; Behr, Pascal; Zambelli, Tomaso; Vorholt, Julia A; Mercer, Jason

2012-08-08

The mechanisms used by viruses to enter and replicate within host cells are subjects of intense investigation. These studies are ultimately aimed at development of new drugs that interfere with these processes. Virus entry and infection are generally monitored by dispensing bulk virus suspensions on layers of cells without accounting for the fate of each virion. Here, we take advantage of the recently developed FluidFM to deposit single vaccinia virions onto individual cells in a controlled manner. While the majority of virions were blocked prior to early gene expression, infection of individual cells increased in a nondeterministic fashion with respect to the number of viruses placed. Microscopic analyses of several stages of the virus lifecycle indicated that this was the result of cooperativity between virions during early stages of infection. These findings highlight the importance of performing controlled virus infection experiments at the single cell level.

Determination of the Shock Properties of Ceramic Corbit 98: 98% Alumina

DTIC Science & Technology

2010-06-01

sapphire or aluminum. A single stage three inch bore gas gun was used to accelerate the projectile for experiments at NPS. Los Alamos National Lab used...stage three inch bore gas gun was used to accelerate the projectile for experiments at NPS. Los Alamos National Lab used a higher performance gun...Gigapascals, one billion pascals of pressure or force per unit area HEL Hugoniot elastic limit LANL Los Alamos National Lab mm Millimeter, or one

Performance of Single-Stage Turbine of Mark 25 Torpedo Power Plant with Two Special Nozzles. II; Efficiency with 20 Degrees-Inlet-Angle Rotor Blades

NASA Technical Reports Server (NTRS)

Schum, Harold J.; Whitney, Warren J.

1949-01-01

A single-stage modification of the turbine from a Mark 25 torpedo power plant was investigated to determine the performance with two nozzle designs in combination with special rotor blades having a 20 inlet angle. The performance is presented in terms of blade, rotor, and brake efficiency as a function of blade-jet speed ratio for pressure ratios of 8, 15 (design), and 20. The blade efficiency with the nozzle having circular pas- sages (K) was equal to or higher than that with the nozzle having rectangular passages (J) for all pressure ratios and speeds investigated. The maximum blade efficiency of 0.571 was obtained with nozzle K at a pressure ratio of 8 and a blade-jet speed ratio of 0.296. The difference in blade efficiency was negligible at a pressure ratio of 8 at the low speeds; the maxim difference was 0.040 at a pressure ratio of 20 and a blade-jet speed ratio of 0.260.

Single-Site Cannulation Venovenous Extracorporeal CO2 Removal as Bridge to Lung Volume Reduction Surgery in End-Stage Lung Emphysema.

PubMed

Redwan, Bassam; Ziegeler, Stephan; Semik, Michael; Fichter, Joachim; Dickgreber, Nicolas; Vieth, Volker; Ernst, Erik Christian; Fischer, Stefan

Lung volume reduction surgery (LVRS) is an important treatment option for end-stage lung emphysema in carefully selected patients. Here, we first describe the application of low-flow venovenous extracorporeal CO2 removal (LFVV-ECCO2R) as bridge to LVRS in patients with end-stage lung emphysema experiencing severe hypercapnia caused by acute failure of the breathing pump. Between March and October 2015, n = 4 patients received single-site LFVV-ECCO2R as bridge to LVRS. Indication for extracorporeal lung support was severe hypercapnia with respiratory acidosis and acute breathing pump failure. Two patients required continuous mechanical ventilation over a temporary tracheostomy and were bed ridden. The other two patients were nearly immobile because of severe dyspnea at rest. Length of preoperative ECCO2R was 14 (1-42) days. All patients underwent unilateral LVRS. Anatomical resection of the right (n = 3) or left (n = 1) upper lobe was performed. Postoperatively, both patients with previous mechanical ventilatory support were successfully weaned. ECCO2R in patients with end-stage lung emphysema experiencing severe hypercapnia caused by acute breathing pump failure is a safe and effective bridging tool to LVRS. In such patients, radical surgery leads to a significant improvement of the performance status and furthermore facilitates respiratory weaning from mechanical ventilation.

Axial and Centrifugal Compressor Mean Line Flow Analysis Method

NASA Technical Reports Server (NTRS)

Veres, Joseph P.

2009-01-01

This paper describes a method to estimate key aerodynamic parameters of single and multistage axial and centrifugal compressors. This mean-line compressor code COMDES provides the capability of sizing single and multistage compressors quickly during the conceptual design process. Based on the compressible fluid flow equations and the Euler equation, the code can estimate rotor inlet and exit blade angles when run in the design mode. The design point rotor efficiency and stator losses are inputs to the code, and are modeled at off design. When run in the off-design analysis mode, it can be used to generate performance maps based on simple models for losses due to rotor incidence and inlet guide vane reset angle. The code can provide an improved understanding of basic aerodynamic parameters such as diffusion factor, loading levels and incidence, when matching multistage compressor blade rows at design and at part-speed operation. Rotor loading levels and relative velocity ratio are correlated to the onset of compressor surge. NASA Stage 37 and the three-stage NASA 74-A axial compressors were analyzed and the results compared to test data. The code has been used to generate the performance map for the NASA 76-B three-stage axial compressor featuring variable geometry. The compressor stages were aerodynamically matched at off-design speeds by adjusting the variable inlet guide vane and variable stator geometry angles to control the rotor diffusion factor and incidence angles.

Space Van system update

NASA Astrophysics Data System (ADS)

Cormier, Len

1992-07-01

The Space Van is a proposed commercial launch vehicle that is designed to carry 1150 kg to a space-station orbit for a price of $1,900,000 per flight in 1992 dollars. This price includes return on preoperational investment. Recurring costs are expected to be about $840,000 per flight. The Space Van is a fully reusable, assisted-single-stage-to orbit system. The most innovative new feature of the Space Van system is the assist-stage concept. The assist stage uses only airbreathing engines for vertical takeoff and vertical landing in the horizontal attitude and for launching the rocket-powered orbiter stage at mach 0.8 and an altitude of about 12 km. The primary version of the orbiter is designed for cargo-only without a crew. However, a passenger version of the Space Van should be able to carry a crew of two plus six passengers to a space-station orbit. Since the Space Van is nearly single-stage, performance to polar orbit drops off significantly. The cargo version should be capable of carrying 350 kg to a 400-km polar orbit. In the passenger version, the Space Van should be able to carry two crew members - or one crew member plus a passenger.

NASA Constellation Program (CxP) Key Driving Requirements and Element Descriptions for International Architecture Working Group (IAWG) Functional Teams Human Transportation Cargo Transportation

NASA Technical Reports Server (NTRS)

Martinez, Roland M.

2009-01-01

The NASA Constellation uncrewed cargo mission delivers cargo to any designated location on the lunar surface (or other staging point) in a single mission. This capability is used to deliver surface infrastructure needed for lunar outpost construction, to provide periodic logistics resupply to support a continuous human lunar presence, and potentially deliver other assets to various locations.In the nominal mission mode, the Altair lunar lander is launched on Ares V into Low Earth Orbit (LEO), following a short Low Earth Orbit (LEO) loiter period, the Earth Departure Stage (EDS) performs the Trans Lunar Injection (TLI) burn and is then jettisoned. The Altair performs translunar trajectory correction maneuvers as necessary and performs the Lunar Orbit Insertion (LOI) burn. Altair then descends to the surface to land near a designated target, presumably in proximity to an Outpost location or another site of interest for exploration.Alternatively, the EDS and Altair Descent Stage could deliver assets to various staging points within their propulsive capabilities.

Deep Vein Thrombosis After Complex Posterior Spine Surgery: Does Staged Surgery Make a Difference?

PubMed

Edwards, Charles C; Lessing, Noah L; Ford, Lisa; Edwards, Charles C

Retrospective review of a prospectively collected database. To assess the incidence of deep vein thrombosis (DVT) associated with single- versus multistage posterior-only complex spinal surgeries. Dividing the physiologic burden of spinal deformity surgery into multiple stages has been suggested as a potential means of reducing perioperative complications. DVT is a worrisome complication owing to its potential to lead to pulmonary embolism. Whether or not staging affects DVT incidence in this population is unknown. Consecutive patients undergoing either single- or multistage posterior complex spinal surgeries over a 12-year period at a single institution were eligible. All patients received lower extremity venous duplex ultrasonographic (US) examinations 2 to 4 days postoperatively in the single-stage group and 2 to 4 days postoperatively after each stage in the multistage group. Multivariate logistic regression was used to assess the independent contribution of staging to developing a DVT. A total of 107 consecutive patients were enrolled-26 underwent multistage surgery and 81 underwent single-stage surgery. The single-stage group was older (63 years vs. 45 years; p < .01) and had a higher Charlson comorbidity index (2.25 ± 1.27 vs. 1.23 ± 1.58; p < .01). More multistage patients had positive US tests than single-stage patients (5 of 26 vs. 6 of 81; 19% vs. 7%; p = .13). Adjusting for all the above-mentioned covariates, a multistage surgery was 8.17 (95% CI 0.35-250.6) times more likely to yield a DVT than a single-stage surgery. Patients who undergo multistage posterior complex spine surgery are at a high risk for developing a DVT compared to those who undergo single-stage procedures. The difference in DVT incidence may be understated as the multistage group had a lower pre- and intraoperative risk profile with a younger age, lower medical comorbidities, and less per-stage blood loss. Copyright © 2017 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.

Coordinates for a High Performance 4:1 Pressure Ratio Centrifugal Compressor

NASA Technical Reports Server (NTRS)

McKain, Ted F.; Holbrook, Greg J.

1997-01-01

The objective of this program was to define the aerodynamic design and manufacturing coordinates for an advanced 4:1 pressure ratio, single stage centrifugal compressor at a 10 lbm/sec flow size. The approach taken was to perform an exact scale of an existing DDA compressor originally designed at a flow size of 3.655 lbm/sec.

Urinary Tract Resections in Advanced-stage Cervical Cancer - A Series of Eight Cases.

PubMed

Oprescu, Dana Nuti; Bacalbasa, Nicolae; Balescu, Irina; Filipescu, Alexandru

2017-06-01

Cervical cancer is one of the most frequent malignancies in women worldwide and is unfortunately diagnosed in advanced stages of the disease. Whenever local invasion is present, neoadjuvant therapy might be needed in order to limit the degree of local invasion. However, in certain cases local invasion persists even after completing the neoadjuvant radiochemotherapy; in these patients more extensive resections might be needed in order to achieve a radical resection. We present a case series of eight patients in whom segmental ureteral or uretero-vesical resections were performed as part of the radical resections for locally advanced cervical tumors. The continuity of the urinary tract was re-established by performing ureteral reimplantation via uretero-neocystostomy, augmentation cystoplasties with ureteral reimplantations. In a single case ureteral reimplantation was not feasible, a definitive cutaneous ureterostomy being performed. The postoperative course was uneventful in seven cases while in a single case urinary leak occurred, necessitating the exteriorization of the ureter in terminal cutaneous ureterostomy. Ureteral resections can be safely performed in patients with locally advanced cervical cancer. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Conceptual Mean-Line Design of Single and Twin-Shaft Oxy-Fuel Gas Turbine in a Semiclosed Oxy-Fuel Combustion Combined Cycle.

PubMed

Sammak, Majed; Thorbergsson, Egill; Grönstedt, Tomas; Genrup, Magnus

2013-08-01

The aim of this study was to compare single- and twin-shaft oxy-fuel gas turbines in a semiclosed oxy-fuel combustion combined cycle (SCOC-CC). This paper discussed the turbomachinery preliminary mean-line design of oxy-fuel compressor and turbine. The conceptual turbine design was performed using the axial through-flow code luax-t, developed at Lund University. A tool for conceptual design of axial compressors developed at Chalmers University was used for the design of the compressor. The modeled SCOC-CC gave a net electrical efficiency of 46% and a net power of 106 MW. The production of 95% pure oxygen and the compression of CO 2 reduced the gross efficiency of the SCOC-CC by 10 and 2 percentage points, respectively. The designed oxy-fuel gas turbine had a power of 86 MW. The rotational speed of the single-shaft gas turbine was set to 5200 rpm. The designed turbine had four stages, while the compressor had 18 stages. The turbine exit Mach number was calculated to be 0.6 and the calculated value of AN 2 was 40 · 10 6 rpm 2 m 2 . The total calculated cooling mass flow was 25% of the compressor mass flow, or 47 kg/s. The relative tip Mach number of the compressor at the first rotor stage was 1.15. The rotational speed of the twin-shaft gas generator was set to 7200 rpm, while that of the power turbine was set to 4800 rpm. A twin-shaft turbine was designed with five turbine stages to maintain the exit Mach number around 0.5. The twin-shaft turbine required a lower exit Mach number to maintain reasonable diffuser performance. The compressor turbine was designed with two stages while the power turbine had three stages. The study showed that a four-stage twin-shaft turbine produced a high exit Mach number. The calculated value of AN 2 was 38 · 10 6 rpm 2 m 2 . The total calculated cooling mass flow was 23% of the compressor mass flow, or 44 kg/s. The compressor was designed with 14 stages. The preliminary design parameters of the turbine and compressor were within established industrial ranges. From the results of this study, it was concluded that both single- and twin-shaft oxy-fuel gas turbines have advantages. The choice of a twin-shaft gas turbine can be motivated by the smaller compressor size and the advantage of greater flexibility in operation, mainly in the off-design mode. However, the advantages of a twin-shaft design must be weighed against the inherent simplicity and low cost of the simple single-shaft design.

The midline-based nasolabial transposition (MNT) flap: an original single-stage technique for nasal tip reconstruction.

PubMed

Beustes-Stefanelli, Matthieu; O'Toole, Greg; Schertenleib, Pierre

2015-04-01

Nasolabial flaps based on the lateral side of the nose for the reconstruction of lateral nasal defects in a single-stage procedure have been described. Similarly, in midline defects, nasolabial flaps can be used but a 2-stage procedure is classically required. The Midline-based Nasolabial Transposition (MNT) flap is presented as a new single-stage procedure for nasal tip reconstruction. Between 2009 and 2011, an MNT flap was used as a single-stage procedure in 3 cases of large nasal defects of the tip where the forehead flap was either contraindicated or rejected as an option by the patient. There were no complications and a satisfactory aesthetic result was achieved in all cases. The MNT flap is a new single-stage procedure for large nasal tip defects and as such represents an interesting alternative to the classical 2-stage forehead and nasolabial flaps, especially in elderly patients.

Performance and control study of a low-pressure-ratio turbojet engine for a drone aircraft

NASA Technical Reports Server (NTRS)

Seldner, K.; Geyser, L. C.; Gold, H.; Walker, D.; Burgner, G.

1972-01-01

The results of analog and digital computer studies of a low-pressure-ratio turbojet engine system for use in a drone vehicle are presented. The turbojet engine consists of a four-stage axial compressor, single-stage turbine, and a fixed area exhaust nozzle. Three simplified fuel schedules and a generalized parameter fuel control for the engine system are presented and evaluated. The evaluation is based on the performance of each schedule or control during engine acceleration from a windmill start at Mach 0.8 and 6100 meters to 100 percent corrected speed. It was found that, because of the higher acceleration margin permitted by the control, the generalized parameter control exhibited the best dynamic performance.

Small, high-pressure liquid oxygen turbopump

NASA Technical Reports Server (NTRS)

Csomor, A.; Sutton, R.

1977-01-01

A small, high-pressure, liquid oxygen turbopump was designed, fabricated, and tested. The pump was of a single-stage, centrifugal type; power to the pump was supplied by a single-stage, partial emission, axial-impulse turbine. Design conditions included an operating speed of 70,000 rpm, pump discharge pressure of 2977 N/sq cm (4318 psia), and a pump flowrate of 16.4 kg/s (36.21 lb/sec). The turbine was propelled by LO2/LH2 combustion products at 1041 K (1874 R) inlet temperature, and at a design pressure ratio of 1.424. The approaches used in the detail analysis and design of the turbopump are described, and fabrication methods are discussed. Data obtained from gas generator tests, turbine performance calibration, and turbopump testing are presented.

Shock Equation of State of Multi-Phase Epoxy-Based Composite (Al-MnO2-Epoxy)

DTIC Science & Technology

2010-10-01

single stage light gas gun , two...using three different loading techniques— single stage light gas gun , two stage light gas gun , and explosive loading—with multiple diagnostic...wave speed. B. Single stage gas gun loading experiments Four gas gun -driven equation of state experiments were conducted at NSWC-Indian Head using

Ascent performance feasibility for next-generation spacecraft

NASA Astrophysics Data System (ADS)

Mancuso, Salvatore Massimo

This thesis deals with the optimization of the ascent trajectories for single-stage suborbital (SSSO), single-stage-to-orbit (SSTO), and two-stage-to-orbit (TSTO) rocket-powered spacecraft. The maximum payload weight problem has been solved using the sequential gradient-restoration algorithm. For the TSTO case, some modifications to the original version of the algorithm have been necessary in order to deal with discontinuities due to staging and the fact that the functional being minimized depends on interface conditions. The optimization problem is studied for different values of the initial thrust-to-weight ratio in the range 1.3 to 1.6, engine specific impulse in the range 400 to 500 sec, and spacecraft structural factor in the range 0.08 to 0.12. For the TSTO configuration, two subproblems are studied: uniform structural factor between stages and nonuniform structural factor between stages. Due to the regular behavior of the results obtained, engineering approximations have been developed which connect the maximum payload weight to the engine specific impulse and spacecraft structural factor; in turn, this leads to useful design considerations. Also, performance sensitivity to the scale of the aerodynamic drag is studied, and it is shown that its effect on payload weight is relatively small, even for drag changes approaching ± 50%. The main conclusions are that: the design of a SSSO configuration appears to be feasible; the design of a SSTO configuration might be comfortably feasible, marginally feasible, or unfeasible, depending on the parameter values assumed; the design of a TSTO configuration is not only feasible, but its payload appears to be considerably larger than that of a SSTO configuration. Improvements in engine specific impulse and spacecraft structural factor are desirable and crucial for SSTO feasibility; indeed, it appears that aerodynamic improvements do not yield significant improvements in payload weight.

Implanted component faults and their effects on gas turbine engine performance

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

MacLeod, J.D.; Taylor, V.; Laflamme, J.C.G.

Under the sponsorship of the Canadian Department of National Defence, the Engine Laboratory of the National Research Council of Canada (NRCC) has established a program for the evaluation of component deterioration on gas turbine engine performance. The effect is aimed at investigating the effects of typical in-service faults on the performance characteristics of each individual engine component. The objective of the program is the development of a generalized fault library, which will be used with fault identification techniques in the field, to reduce unscheduled maintenance. To evaluate the effects of implanted faults on the performance of a single spool engine,more » such as an Allison T56 turboprop engine, a series of faulted parts were installed. For this paper the following faults were analyzed: (a) first-stage turbine nozzle erosion damage; (b) first-stage turbine rotor blade untwist; (c) compressor seal wear; (d) first and second-stage compressor blade tip clearance increase. This paper describes the project objectives, the experimental installation, and the results of the fault implantation on engine performance. Discussed are performance variations on both engine and component characteristics. As the performance changes were significant, a rigorous measurement uncertainty analysis is included.« less

Cost analysis and outcomes of a second-look tympanoplasty-mastoidectomy strategy for cholesteatoma.

PubMed

Crowson, Matthew G; Ramprasad, Vaibhav H; Chapurin, Nikita; Cunningham, Calhoun D; Kaylie, David M

2016-11-01

To analyze cost and compare cholesteatoma recidivism and hearing outcomes with single-stage and second-look operative strategies. Retrospective review and cost analysis. Adult and pediatric patients who underwent a tympanoplasty with mastoidectomy for cholesteatoma with a single-stage or second-look operative strategy were identified. Variables included procedure approach, residual or recurrent cholesteatoma, ossicular chain reconstruction frequency, and operative complications. Audiologic outcomes included pre-/postoperative air bone gap (ABG) and word recognition score (WRS). Cost analysis included charges for consultation and follow-up visits, surgical procedures, computed tomography temporal bone scans, and audiology visits. One hundred and six patients had a tympanoplasty with mastoidectomy for cholesteatoma, with 80 canal wall-up procedures (CWU) as initial approach. Of these, 46 (57.5%) CWU patients had a planned second look. Two (4.3%) CWU patients had recurrent cholesteatoma and 20 (43.4%) had residual identified at second look. Four (11.7%) single-stage CWU strategy patients developed recurrent cholesteatoma. There was no significant difference in pre-/postoperative ABG and WRS between second look and single stage (P > 0.05). Compared to second-look patients, single-stage patients had significantly fewer postoperative visits (6.32 vs. 10.4; P = 0.007), and significantly lower overall charges for care ($23,529. vs. $41.411; P < 0.0001). The goal of cholesteatoma surgery is to produce a safe ear, and a second-look strategy after CWU has historically been used to evaluate for recurrent or residual disease. The cholesteatoma recurrence rate at a second look after a CWU tympanoplasty-mastoidectomy is low. Costs of operative procedures are a significant proportion of healthcare resource expenditures. Considering the low rate of cholesteatoma recurrence and relatively high cost of care, implementation of a second-look strategy should be individually tailored and not universally performed. 4. Laryngoscope, 126:2574-2579, 2016. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Single-stage intraoperative transhepatic biliary stenting in patients with unresectable hepatobiliary pancreatic tumors.

PubMed

Iwasaki, Yoshimi; Kubota, Keiichi; Kita, Junji; Katoh, Masato; Shimoda, Mitsugi; Sawada, Tokihiko; Iso, Yukihiro

2013-02-01

The current study was conducted to evaluate the safety and utility of intraoperative transhepatic biliary stenting (ITBS) in patients with unresectable malignant biliary obstruction (UMBO) diagnosed intraoperatively. In this study, 50 patients who underwent ITBS for UMBO between April 2001 and May 2009 were retrospectively reviewed. For 26 patients who underwent preoperative percutaneous transhepatic biliary drainage (PTBD), the expandable metallic stent (EMS) was inserted intraoperatively by the PTBD route in a single stage. For 24 patients, the intrahepatic bile ducts were intentionally dilated by injection of saline via the endoscopic nasobiliary drainage or the percutaneous transhepatic gallbladder drainage route, and the puncture was performed under intraoperative ultrasound guidance followed by guidewire and catheter insertion. Thereafter, the EMS was placed in the same manner. The initial postoperative complications and long-term results of ITBS were evaluated. In all cases, ITBS was technically successful. Stenting alone was performed in 22 patients and stenting combined with other procedures in 28 patients. Hospital mortality occurred for three patients (6 %), and complication-related mortality occurred in two cases (4 %). There were nine cases (18 %) of postoperative complications. The median survival time was 179 days, and the EMS patency time was 137 days. During the follow-up period, EMS occlusion occurred in 23 cases (46 %). Best supportive care was a significant independent risk factor for early mortality within 100 days after ITBS (p = 0.020, odds ratio, 9.398). Single-stage ITBS is feasible for palliation of UMBO and seems to have a low complication rate.

Early Language Abilities of High-Risk Infants.

ERIC Educational Resources Information Center

Hubatch, Leona M.; And Others

1985-01-01

Ten children with a history of prematurity and respiratory distress syndrome (RDS) were matched with 101 full-term controls in the single-word stage of language. Control subjects demonstrated superior performance on all receptive language and child verbosity measures despite their younger age. (Author/CL)

Nitrogen removal performance and loading capacity of a novel single-stage nitritation-anammox system with syntrophic micro-granules.

PubMed

Wang, Shaopo; Liu, Yuan; Niu, Qigui; Ji, Jiayuan; Hojo, Toshimasa; Li, Yu-You

2017-07-01

The operation performance of a novel micro-granule based syntrophic system of nitritation and anammox was studied by controlling the oxygen concentration and maintaining a constant temperature of 25°C. With the oxygen concentration of around 0.11 (<0.15)mg/L, the single-stage nitritation-anammox system was startup successfully at a nitrogen loading rate (NLR) of 1.5kgN/m 3 /d. The reactor was successfully operated at volumetric N loadings ranging from 0.5 to 2.5kgN/m 3 /d with a high nitrogen removal of 82%. The microbial community was composed by ammonia oxidizing bacteria (AOB) and anammox bacteria forming micro-granules with an average diameter of 0.8mm and good settleability. Results from pyrosequencing analysis revealed that Ca. Kuenenia and Nitrosomonas were selected and enriched in the community over the startup period, and these were identified as the dominant anammox bacteria and AOB species, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Performance improvement of a centrifugal compressor stage by using different vaned diffusers

NASA Astrophysics Data System (ADS)

Zhang, Y. C.; Kong, X. Z.; Li, F.; Sun, W.; Chen, Q. G.

2013-12-01

The vaneless diffuser (VLD) is usually adopted in the traditional design of the multi-stage centrifugal compressor because of the stage's match problem. The drawback of the stage with vaneless diffusers is low efficiency. In order to increase the efficiency and at the same time, induce no significant decline in the operating range of the stage, three different types of vaned diffusers are designed and numerically investigated: the traditional vaned diffuser (TVD), the low-solidity cascade diffuser (LSD) and the partial-height vane diffuser (PVD). These three types of vaned diffusers have different influences on the performance of the centrifugal compressor. In the present investigation, the first part investigates the performance of a centrifugal compressor stage with three different vaned diffusers. The second part studies the influences of the height and the position of partial height vanes on the stage performance, and discusses the matching problem between the PVD and the downstream return channel. The stage investigated in this paper includes the impeller, the diffuser, the bend and the return channel. In the process of numerical investigation, the flow is assumed to be steady, and this process includes calculation and simulation. The calculation of 3-D turbulent flow in the stage uses the commercial CFD code NUMECA together with the Spalart-Allmaras turbulence model. The simulation of the computational region includes the impeller passages, the diffuser passages and return channel passages. The structure and surrounding region are assumed to have a perfect cyclic symmetry, so the single channel model and periodic boundary condition are applied at the middle of the passage, that is to reduce the calculation region to only one region. The investigation showed that the low-solidity cascade diffuser would be a better choice as a middle course for the first stage of the multistage centrifugal compressor. Besides, the influences of the height and the position of partial height vanes on the stage performance are intensively investigated and concluded at the design point, the isentropic efficiency and the static pressure ratio of the stage are improved with the increasing of the partial vane's height, and that installing the half-height vanes on the shroud side the stage would obtain a more uniform diffuser outflow and a better aerodynamic performance.

Exprimental Results of the First Two Stages of an Advanced Transonic Core Compressor Under Isolated and Multi-Stage Conditions.

NASA Technical Reports Server (NTRS)

Prahst, Patricia S.; Kulkarni, Sameer; Sohn, Ki H.

2015-01-01

NASA's Environmentally Responsible Aviation (ERA) Program calls for investigation of the technology barriers associated with improved fuel efficiency for large gas turbine engines. Under ERA, the highly loaded core compressor technology program attempts to realize the fuel burn reduction goal by increasing overall pressure ratio of the compressor to increase thermal efficiency of the engine. Study engines with overall pressure ratio of 60 to 70 are now being investigated. This means that the high pressure compressor would have to almost double in pressure ratio while keeping a high level of efficiency. NASA and GE teamed to address this challenge by testing the first two stages of an advanced GE compressor designed to meet the requirements of a very high pressure ratio core compressor. Previous test experience of a compressor which included these front two stages indicated a performance deficit relative to design intent. Therefore, the current rig was designed to run in 1-stage and 2-stage configurations in two separate tests to assess whether the bow shock of the second rotor interacting with the upstream stage contributed to the unpredicted performance deficit, or if the culprit was due to interaction of rotor 1 and stator 1. Thus, the goal was to fully understand the stage 1 performance under isolated and multi-stage conditions, and additionally to provide a detailed aerodynamic data set for CFD validation. Full use was made of steady and unsteady measurement methods to understand fluid dynamics loss source mechanisms due to rotor shock interaction and endwall losses. This paper will present the description of the compressor test article and its measured performance and operability, for both the single stage and two stage configurations. We focus the paper on measurements at 97% corrected speed with design intent vane setting angles.

Performance analysis of single stage libr-water absorption machine operated by waste thermal energy of internal combustion engine: Case study

NASA Astrophysics Data System (ADS)

Sharif, Hafiz Zafar; Leman, A. M.; Muthuraman, S.; Salleh, Mohd Najib Mohd; Zakaria, Supaat

2017-09-01

Combined heating, cooling, and power is also known as Tri-generation. Tri-generation system can provide power, hot water, space heating and air -conditioning from single source of energy. The objective of this study is to propose a method to evaluate the characteristic and performance of a single stage lithium bromide-water (LiBr-H2O) absorption machine operated with waste thermal energy of internal combustion engine which is integral part of trigeneration system. Correlations for computer sensitivity analysis are developed in data fit software for (P-T-X), (H-T-X), saturated liquid (water), saturated vapor, saturation pressure and crystallization temperature curve of LiBr-H2O Solution. Number of equations were developed with data fit software and exported into excel work sheet for the evaluation of number of parameter concerned with the performance of vapor absorption machine such as co-efficient of performance, concentration of solution, mass flow rate, size of heat exchangers of the unit in relation to the generator, condenser, absorber and evaporator temperatures. Size of vapor absorption machine within its crystallization limits for cooling and heating by waste energy recovered from exhaust gas, and jacket water of internal combustion engine also presented in this study to save the time and cost for the facilities managers who are interested to utilize the waste thermal energy of their buildings or premises for heating and air conditioning applications.

Experimental vibration damping characteristics of the third-stage rotor of a three-stage transonic axial-flow compressor

NASA Technical Reports Server (NTRS)

Newman, Frederick A.

1988-01-01

Rotor blade aerodynamic damping is experimentally determined in a three-stage transonic axial flow compressor having design aerodynamic performance goals of 4.5:1 pressure ratio and 65.5 lbm/sec weight flow. The combined damping associated with each mode is determined by a least squares fit of a single degree of freedom system transfer function to the nonsynchronous portion of the rotor blade strain gage output power spectra. The combined damping consists of the aerodynanmic damping and the structural and mechanical damping. The aerodynamic damping varies linearly with the inlet total pressure for a given corrected speed, weight flow, and pressure ratio while the structural and mechanical damping is assumed to remain constant. The combined damping is determined at three inlet total pressure levels to obtain the aerodynamic damping. The third-stage rotor blade aerodynamic damping is presented and discussed for the design equivalent speed with the stator blades reset for maximum efficiency. The compressor overall performance and experimental Campbell diagrams for the third-stage rotor blade row are also presented.

Catheter interventions in the staged management of hypoplastic left heart syndrome.

PubMed

Reinhardt, Zdenka; De Giovanni, Joseph; Stickley, John; Bhole, Vinay K; Anderson, Benjamin; Murtuza, Bari; Mehta, Chetan; Miller, Paul; Dhillon, Rami; Stumper, Oliver

2014-04-01

To analyse the current practice and contribution of catheter interventions in the staged management of patients with hypoplastic left heart syndrome. This study is a retrospective case note review of 527 patients undergoing staged Norwood/Fontan palliation at a single centre between 1993 and 2010. Indications and type of catheter interventions were reviewed over a median follow-up period of 7.5 years. A staged Norwood/Fontan palliation for hypoplastic left heart syndrome was performed in 527 patients. The 30-day survival rate after individual stages was 76.5% at Stage I, 96.3% at Stage II, and 99.4% at Stage III. A total of 348 interventions were performed in 189 out of 527 patients. Freedom from catheter intervention in survivors was 58.2% before Stage II and 46.7% before Stage III. Kaplan-Meier freedom from intervention post Fontan completion was 55% at 10.8 years of follow-up. Post-stage I interventions were mostly directed to relieve aortic arch obstruction--84 balloon angioplasties--and augment pulmonary blood flow--15 right ventricle-to-pulmonary conduit interventions; post-Stage II interventions centred on augmenting size of the left pulmonary artery--73 procedures and abolishing systemic venous collaterals--32 procedures. After Stage III, the focus was on manipulating the size of the fenestration--42 interventions--and the left pulmonary artery -31 procedures. Interventional cardiac catheterisation constitutes an integral part in the staged palliative management of patients with hypoplastic left heart syndrome. Over one-third (37%) of patients undergoing staged palliation required catheter intervention over the follow-up period.

The Incidence of Complications in Single-stage Endoscopic Stone Removal for Patients with Common Bile Duct Stones: A Propensity Score Analysis.

PubMed

Saito, Hirokazu; Kadono, Yoshihiro; Kamikawa, Kentaro; Urata, Atsushi; Imamura, Haruo; Matsushita, Ikuo; Kakuma, Tatsuyuki; Tada, Shuji

2018-02-15

Objective Single-stage endoscopic stone removal for choledocholithiasis is an advantageous approach because it is associated with a shorter hospital stay; however, few studies have reported the incidence of complications related to this procedure in detail. The aim of this study was to examine the incidence of complications and efficacy of this procedure. Methods This retrospective study investigated the incidence of complications in 345 patients with naive papilla who underwent therapeutic endoscopic retrograde cholangiopancreatography (ERCP) for choledocholithiasis at three institutions between April 2014 and March 2016 by a propensity score analysis. The efficacy of single-stage endoscopic stone removal was assessed based on a hospital stay of within 7 days and the number of ERCP attempts. Results Among 114 patients who underwent single-stage endoscopic stone removal, 15 patients (13.2%) experienced complications. Among the remaining 231 patients in the two-stage endoscopic stone removal group, complications were observed in 17 patients (7.4%). The propensity score analysis, which was adjusted for confounding factors, revealed that single-stage endoscopic stone removal was not a significant risk factor for complications (p=0.52). In patients in whom >10 min was required for deep cannulation, single-stage endoscopic stone removal was not a significant risk factor for complications in the propensity score analysis (p=0.37). In the single-stage group, the proportion of patients with a hospital stay of within 7 days was significantly higher and the number of ERCP attempts was significantly lower in comparison to the two-stage group (p <0.0001 and <0.0001, respectively). Conclusion Single-stage endoscopic stone removal did not increase the incidence of complications associated with ERCP and was effective for reducing the hospital stay and the number of ERCP attempts.

The Incidence of Complications in Single-stage Endoscopic Stone Removal for Patients with Common Bile Duct Stones: A Propensity Score Analysis

PubMed Central

Saito, Hirokazu; Kadono, Yoshihiro; Kamikawa, Kentaro; Urata, Atsushi; Imamura, Haruo; Matsushita, Ikuo; Kakuma, Tatsuyuki; Tada, Shuji

2017-01-01

Objective Single-stage endoscopic stone removal for choledocholithiasis is an advantageous approach because it is associated with a shorter hospital stay; however, few studies have reported the incidence of complications related to this procedure in detail. The aim of this study was to examine the incidence of complications and efficacy of this procedure. Methods This retrospective study investigated the incidence of complications in 345 patients with naive papilla who underwent therapeutic endoscopic retrograde cholangiopancreatography (ERCP) for choledocholithiasis at three institutions between April 2014 and March 2016 by a propensity score analysis. The efficacy of single-stage endoscopic stone removal was assessed based on a hospital stay of within 7 days and the number of ERCP attempts. Results Among 114 patients who underwent single-stage endoscopic stone removal, 15 patients (13.2%) experienced complications. Among the remaining 231 patients in the two-stage endoscopic stone removal group, complications were observed in 17 patients (7.4%). The propensity score analysis, which was adjusted for confounding factors, revealed that single-stage endoscopic stone removal was not a significant risk factor for complications (p=0.52). In patients in whom >10 min was required for deep cannulation, single-stage endoscopic stone removal was not a significant risk factor for complications in the propensity score analysis (p=0.37). In the single-stage group, the proportion of patients with a hospital stay of within 7 days was significantly higher and the number of ERCP attempts was significantly lower in comparison to the two-stage group (p <0.0001 and <0.0001, respectively). Conclusion Single-stage endoscopic stone removal did not increase the incidence of complications associated with ERCP and was effective for reducing the hospital stay and the number of ERCP attempts. PMID:29151506

On the economics of staging for reusable launch vehicles

NASA Astrophysics Data System (ADS)

Griffin, Michael D.; Claybaugh, William R.

1996-03-01

There has been much recent discussion concerning possible replacement systems for the current U.S. fleet of launch vehicles, including both the shuttle and expendable vehicles. Attention has been focused upon the feasibility and potential benefits of reusable single-stage-to-orbit (SSTO) launch systems for future access to low Earth orbit (LEO). In this paper we assume the technical feasibility of such vehicles, as well as the benefits to be derived from system reusability. We then consider the benefits of launch vehicle staging from the perspective of economic advantage rather than performance necessity. Conditions are derived under which two-stage-to-orbit (TSTO) launch systems, utilizing SSTO-class vehicle technology, offer a relative economic advantage for access to LEO.

Thermodynamic performance of the 3-stage ADR for the Astro-H Soft-X-ray Spectrometer instrument

NASA Astrophysics Data System (ADS)

Shirron, Peter J.; Kimball, Mark O.; James, Bryan L.; Muench, Theodore; DiPirro, Michael J.; Bialas, Thomas G.; Sneiderman, Gary A.; Porter, Frederick S.; Kelley, Richard L.

2016-03-01

The Soft X-ray Spectrometer (SXS) instrument (Mitsuda et al., 2010) [1] on Astro-H (Takahashi et al., 2010) [2] will use a 3-stage ADR (Shirron et al., 2012) to cool the microcalorimeter array to 50 mK. In the primary operating mode, two stages of the ADR cool the detectors using superfluid helium at ⩽1.20 K as the heat sink (Fujimoto et al., 2010). In the secondary mode, which is activated when the liquid helium is depleted, the ADR uses a 4.5 K Joule-Thomson cooler as its heat sink. In this mode, all three stages operate together to continuously cool the (empty) helium tank and single-shot cool the detectors. The flight instrument - dewar, ADR, detectors and electronics - were integrated in 2014 and have since undergone extensive performance testing. This paper presents a thermodynamic analysis of the ADR's operation, including cooling capacity, heat rejection to the heat sinks, and various measures of efficiency.

Multiple kernel learning using single stage function approximation for binary classification problems

NASA Astrophysics Data System (ADS)

Shiju, S.; Sumitra, S.

2017-12-01

In this paper, the multiple kernel learning (MKL) is formulated as a supervised classification problem. We dealt with binary classification data and hence the data modelling problem involves the computation of two decision boundaries of which one related with that of kernel learning and the other with that of input data. In our approach, they are found with the aid of a single cost function by constructing a global reproducing kernel Hilbert space (RKHS) as the direct sum of the RKHSs corresponding to the decision boundaries of kernel learning and input data and searching that function from the global RKHS, which can be represented as the direct sum of the decision boundaries under consideration. In our experimental analysis, the proposed model had shown superior performance in comparison with that of existing two stage function approximation formulation of MKL, where the decision functions of kernel learning and input data are found separately using two different cost functions. This is due to the fact that single stage representation helps the knowledge transfer between the computation procedures for finding the decision boundaries of kernel learning and input data, which inturn boosts the generalisation capacity of the model.

Single stage, low noise, advanced technology fan. Volume 5: Fan acoustics. Section 2: One-third octave data tabulations and selected narrowband traces

NASA Technical Reports Server (NTRS)

Jutras, R. R.

1976-01-01

The raw-acoustic data corrected to standard day, from acoustic tests performed on a 0.508-scale fan vehicle of a 111,300 newton thrust, full-size engine, which has application on an advanced transport aircraft, are presented. The single-stage advanced technology fan was designed to a pressure ratio of 1.8 at a tip speed of 503 m/sec to achieve the desired pressure ratio in a single-stage fan with low radius ratio, and to maintain adequate stall margin. The two basic approaches taken in the acoustic design were: (1) minimization of noise at the source, and (2) suppression of the generated noise in the inlet and bypass exhaust duct. Suppression of the generated noise was accomplished in the inlet through use of the hybrid concept (wall acoustic treatment plus airflow acceleration suppression) and in the exhaust duct with extensive acoustic treatment including a splitter. The goal of the design was attainment of twenty effective perceived noise decibels. The suppression goal of FAR 36-20 was not reached, but improvements in the technology of both front and aft fan-noise suppression were realized.

Upgrading of the symbiosis of Nitrosomanas and anammox bacteria in a novel single-stage partial nitritation-anammox system: Nitrogen removal potential and Microbial characterization.

PubMed

Liu, Yuan; Niu, Qigui; Wang, Shaopo; Ji, Jiayuan; Zhang, Yu; Yang, Min; Hojo, Toshimasa; Li, Yu-You

2017-11-01

A novel single-stage partial nitritation-anammox process equipped with porous functional suspended carriers was developed at 25°C in a CSTR by controlling dissolved oxygen <0.3mg/L. The nitrogen removal performance was almost unchanged over a nitrogen loading rate ranging from 0.5 to 2.5kgNH 4 + -N/m 3 /d with a high nitrogen removal efficiency of 81.1%. The specific activity of AOB and anammox bacteria was of 3.00g-N/g-MLVSS/d (the suspended sludge), 3.56g-N/g-MLVSS/d (the biofilm sludge), respectively. The results of pyrosequencing revealed that Nitrosomonas (5.66%) and Candidatus_Kuenenia (4.95%) were symbiotic in carriers while Nitrosomonas (40.70%) was predominant in the suspended flocs. Besides, two specific types of heterotrophic filamentous bacteria in the suspended flocs (Haliscomenobacter) and the functional carrier biofilm (Longilinea) were shown to confer structural integrity to the aggregates. The novel single-stage partial nitritation-anammox process equipped with functional suspended carriers was shown to have good potential for the nitrogen-rich wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantum jointly assisted cloning of an unknown three-dimensional equatorial state

NASA Astrophysics Data System (ADS)

Ma, Peng-Cheng; Chen, Gui-Bin; Li, Xiao-Wei; Zhan, You-Bang

2018-02-01

We present two schemes for perfectly cloning an unknown single-qutrit equatorial state with assistance from two and N state preparers, respectively. In the first scheme, the sender wishes to teleport an unknown single-qutrit equatorial state from two state preparers to a remote receiver, and then to create a perfect copy of the unknown state at her location. The scheme consists of two stages. The first stage of the scheme requires the usual teleportation. In the second stage, to help the sender realize the quantum cloning, two state preparers perform single-qutrit projective measurements on their own qutrits from the sender, then the sender can acquire a perfect copy of the unknown state. It is shown that, only if the two state preparers collaborate with each other, the sender can create a copy of the unknown state by means of some appropriate unitary operations. In the second scheme, we generalized the jointly assisted cloning in the first scheme to the case of N state prepares. In the present schemes, the total probability of success for assisted cloning of a perfect copy of the unknown state can reach 1.

The efficacy of intravenous ketorolac for pain relief in single-stage adjustable strabismus surgery: a prospective, randomized, placebo-controlled trial

PubMed Central

Rhiu, S; Chung, S A; Kim, W K; Chang, J H; Bae, S J; Lee, J B

2011-01-01

Purpose To determine the efficacy of preoperative intravenous ketorolac in reducing intraoperative and postoperative pain and improving patient satisfaction in patients undergoing single-stage adjustable strabismus surgery. Methods A prospective, randomized, placebo-controlled clinical trial was performed with 67 patients who underwent horizontal recti muscle surgery with adjustable sutures. The test group received intravenous ketorolac (60 mg) before surgery, and the control group received intravenous normal saline. Topical 0.5% proparacaine was administered to both groups during surgery. Vital signs including heart rate and blood pressure were recorded every 10 min throughout the surgery. The patients were asked to rate their maximum intraoperative and postoperative pain scores using a numerical pain rating scale. Patient satisfaction was also assessed using a five-point analogue scale. Results The ketorolac-premedicated patients had less pain both during and after surgery (P=0.033 and P=0.024, respectively). There were no differences in vital signs during surgery and patient satisfaction between the two groups. Conclusions Intravenous ketorolac, when administered preoperatively for single-stage adjustable strabismus surgery under topical anaesthesia, was effective in reducing pain during and after surgery. PMID:21102493

Dynamic working memory performance in individuals with single-domain amnestic mild cognitive impairment.

PubMed

Guild, Emma B; Vasquez, Brandon P; Maione, Andrea M; Mah, Linda; Ween, Jon; Anderson, Nicole D

2014-01-01

Previous studies have observed poorer working memory performance in individuals with amnestic mild cognitive impairment than in healthy older adults. It is unclear, however, whether these difficulties are true only of the multiple-domain clinical subtype in whom poorer executive functioning is common. The current study examined working memory, as measured by the self-ordered pointing task (SOPT) and an n-back task, in healthy older adults and adults with single-domain amnestic mild cognitive impairment (aMCI). Individuals with single-domain aMCI committed more errors and required longer to develop an organizational strategy on the SOPT. The single-domain aMCI group did not differ from healthy older adults on the 1-back or 2-back, but had poorer discrimination on the 3-back task. This is, to our knowledge, the first characterization of dynamic working memory performance in a single-domain aMCI group. These results lend support for the idea that clinical amnestic MCI subtypes may reflect different stages on a continuum of progression to dementia and question whether standardized measures of working memory (span tasks) are sensitive enough to capture subtle changes in performance.

Routine conventional karyotyping of lymphoma staging bone marrow samples does not contribute clinically relevant information.

PubMed

Nardi, Valentina; Pulluqi, Olja; Abramson, Jeremy S; Dal Cin, Paola; Hasserjian, Robert P

2015-06-01

Bone marrow (BM) evaluation is an important part of lymphoma staging, which guides patient management. Although positive staging marrow is defined as morphologically identifiable disease, such samples often also include flow cytometric analysis and conventional karyotyping. Cytogenetic analysis is a labor-intensive and costly procedure and its utility in this setting is uncertain. We retrospectively reviewed pathological reports of 526 staging marrow specimens in which conventional karyotyping had been performed. All samples originated from a single institution from patients with previously untreated Hodgkin and non-Hodgkin lymphomas presenting in an extramedullary site. Cytogenetic analysis revealed clonal abnormalities in only eight marrow samples (1.5%), all of which were positive for lymphoma by morphologic evaluation. Flow cytometry showed a small clonal lymphoid population in three of the 443 morphologically negative marrow samples (0.7%). Conventional karyotyping is rarely positive in lymphoma staging marrow samples and, in our cohort, the BM karyotype did not contribute clinically relevant information in the vast majority of cases. Our findings suggest that karyotyping should not be performed routinely on BM samples taken to stage previously diagnosed extramedullary lymphomas unless there is pathological evidence of BM involvement by lymphoma. © 2015 Wiley Periodicals, Inc.

A New Technique for Achieving Impact Velocities Greater Than 10 km/sec

NASA Astrophysics Data System (ADS)

Piekutowski, A. J.

2001-05-01

This Contractor Report describes and presents the results of work that was done in an attempt to develop an augmented acceleration technique that would launch small projectiles of known shape, mass, and state to velocities of 10 km/sec and higher. The higher velocities were to be achieved by adding a third stage to a conventional two-stage, light-gas gun and using a modified firing cycle for the third stage. The technique did not achieve the desired results and was modified for use during the development program. Since the design of the components used for the augmented-acceleration, three-stage launcher could be readily adapted for use as a three-stage launcher that used a single-stage acceleration cycle; the remainder of the contract period was spent performing test firings using the modified three-stage launcher. Work with the modified three-stage launcher, although not complete, did produce test firings in which an 0.11-g cylindrical nylon projectile was launched to a velocity of 8.65 km/sec.

A New Technique for Achieving Impact Velocities Greater Than 10 km/sec

NASA Technical Reports Server (NTRS)

Piekutowski, A. J.; Nolen, Angie (Technical Monitor)

2001-01-01

This Contractor Report describes and presents the results of work that was done in an attempt to develop an augmented acceleration technique that would launch small projectiles of known shape, mass, and state to velocities of 10 km/sec and higher. The higher velocities were to be achieved by adding a third stage to a conventional two-stage, light-gas gun and using a modified firing cycle for the third stage. The technique did not achieve the desired results and was modified for use during the development program. Since the design of the components used for the augmented-acceleration, three-stage launcher could be readily adapted for use as a three-stage launcher that used a single-stage acceleration cycle; the remainder of the contract period was spent performing test firings using the modified three-stage launcher. Work with the modified three-stage launcher, although not complete, did produce test firings in which an 0.11-g cylindrical nylon projectile was launched to a velocity of 8.65 km/sec.

Technology Roadmap for Dual-Mode Scramjet Propulsion to Support Space-Access Vision Vehicle Development

NASA Technical Reports Server (NTRS)

Cockrell, Charles E., Jr.; Auslender, Aaron H.; Guy, R. Wayne; McClinton, Charles R.; Welch, Sharon S.

2002-01-01

Third-generation reusable launch vehicle (RLV) systems are envisioned that utilize airbreathing and combined-cycle propulsion to take advantage of potential performance benefits over conventional rocket propulsion and address goals of reducing the cost and enhancing the safety of systems to reach earth orbit. The dual-mode scramjet (DMSJ) forms the core of combined-cycle or combination-cycle propulsion systems for single-stage-to-orbit (SSTO) vehicles and provides most of the orbital ascent energy. These concepts are also relevant to two-stage-to-orbit (TSTO) systems with an airbreathing first or second stage. Foundation technology investments in scramjet propulsion are driven by the goal to develop efficient Mach 3-15 concepts with sufficient performance and operability to meet operational system goals. A brief historical review of NASA scramjet development is presented along with a summary of current technology efforts and a proposed roadmap. The technology addresses hydrogen-fueled combustor development, hypervelocity scramjets, multi-speed flowpath performance and operability, propulsion-airframe integration, and analysis and diagnostic tools.

Accuracy of Oxygen Flow Delivered by Compressed-Gas Cylinders in Hospital and Prehospital Emergency Care.

PubMed

Duprez, Frédéric; Michotte, Jean Bernard; Cuvelier, Gregory; Legrand, Alexandre; Mashayekhi, Sharam; Reychler, Gregory

2018-03-01

Oxygen cylinders are widely used both in hospital and prehospital care. Excessive or inappropriate F IO 2 may be critical for patients with hypercapnia or hypoxia. Moreover, over-oxygenation could be deleterious in ischemic disorders. Supplemental oxygen from oxygen cylinder should therefore be delivered accurately. The aim of this study was to assess the accuracy of oxygen flows for oxygen cylinder in hospital and prehospital care. A prospective trial was conducted to evaluate accuracy of delivered oxygen flows (2, 4, 6, 9 and 12 L/min) for different oxygen cylinder ready for use in different hospital departments. Delivered flows were analyzed randomly using a calibrated thermal mass flow meter. Two types of oxygen cylinder were evaluated: 78 oxygen cylinder with a single-stage regulator and 70 oxygen cylinder with a dual-stage regulator. Delivered flows were compared to the required oxygen flow. The residual pressure value for each oxygen cylinder was considered. A coefficient of variation was calculated to compare the variability of the delivered flow between the two types of oxygen cylinder. The median values of delivered flows were all ≥ 100% of the required flow for single stage (range 100-109%) and < 100% of required flow for dual stage (range 95-97%). The median values of the delivered flow differed between single and dual stage. It was found that single stage is significantly higher than dual stage ( P = .01). At low flow, the dispersion of the measures for single stage was higher than with a high oxygen flow. Delivered flow differences were also found between low and high residual pressures, but only with single stage ( P = .02). The residual pressure for both oxygen cylinders (no. = 148) ranged from 73 to 2,900 pounds per square inch, and no significant difference was observed between the 2 types ( P = .86). The calculated coefficient of variation ranged from 7% (±1%) for dual stage to 8% (±2%) for single stage. This study shows good accuracy of oxygen flow delivered via oxygen cylinders. This accuracy was higher with dual stage. Single stage was also accurate, however, at low flow this accuracy is slightly less. Moreover, with single stage, when residual pressure decreases, the median value of delivered flow decreased. Copyright © 2018 by Daedalus Enterprises.

A two-stage spectrum sensing scheme based on energy detection and a novel multitaper method

NASA Astrophysics Data System (ADS)

Qi, Pei-Han; Li, Zan; Si, Jiang-Bo; Xiong, Tian-Yi

2015-04-01

Wideband spectrum sensing has drawn much attention in recent years since it provides more opportunities to the secondary users. However, wideband spectrum sensing requires a long time and a complex mechanism at the sensing terminal. A two-stage wideband spectrum sensing scheme is considered to proceed spectrum sensing with low time consumption and high performance to tackle this predicament. In this scheme, a novel multitaper spectrum sensing (MSS) method is proposed to mitigate the poor performance of energy detection (ED) in the low signal-to-noise ratio (SNR) region. The closed-form expression of the decision threshold is derived based on the Neyman-Pearson criterion and the probability of detection in the Rayleigh fading channel is analyzed. An optimization problem is formulated to maximize the probability of detection of the proposed two-stage scheme and the average sensing time of the two-stage scheme is analyzed. Numerical results validate the efficiency of MSS and show that the two-stage spectrum sensing scheme enjoys higher performance in the low SNR region and lower time cost in the high SNR region than the single-stage scheme. Project supported by the National Natural Science Foundation of China (Grant No. 61301179), the China Postdoctoral Science Foundation (Grant No. 2014M550479), and the Doctorial Programs Foundation of the Ministry of Education, China (Grant No. 20110203110011).

Rho-Isp Revisited and Basic Stage Mass Estimating for Launch Vehicle Conceptual Sizing Studies

NASA Technical Reports Server (NTRS)

Kibbey, Timothy P.

2015-01-01

A single metric for judging between two candidate propellant combinations for a given application is sought. By using the ideal rocket equation, the essential link between propellant density and specific impulse as the two primary performance drivers can be demonstrated.

The Potential of a Cascaded TEG System for Waste Heat Usage in Railway Vehicles

NASA Astrophysics Data System (ADS)

Wilbrecht, Sebastian; Beitelschmidt, Michael

2018-02-01

This work focuses on the conceptual design and optimization of a near series prototype of a high-power thermoelectric generator system (TEG system) for diesel-electric locomotives. The replacement of the silencer in the exhaust line enables integration with already existing vehicles. However, compliance with the technical and legal frameworks and the assembly space requirements is just as important as the limited exhaust back pressure, the high power density and the low life cycle costs. A special emphasis is given to the comparison of cascaded two-stage Bi2Te3 and Mg2Si0.4Sn0.6/MnSi1.81 modules with single-stage Bi2Te3 modules, both manufactured in lead-frame technology. In addition to the numerous, partly competing boundary conditions for the use in rail vehicles, the additional degree of freedom from the cascaded thermoelectric modules (TEM) is considered. The problem is investigated by coupling one-dimensional multi-domain simulations with an optimization framework using a genetic algorithm. The achievable electrical power of the single-stage system is significantly higher, at 3.2 kW, than the performance of the two-stage system (2.5 kW). Although the efficiency of the two-stage system is 44.2% higher than the single-stage system, the overall power output is 22.8% lower. This is because the lower power density and the lower number of TEM more than compensates the better efficiency. Hence, the available installation space, and thus the power density, is a critical constraint for the design of TEG systems. Furthermore, for applications recovering exhaust gas enthalpy, the large temperature drop across the heat exchanger is characteristic and must be considered carefully within the design process.

The Potential of a Cascaded TEG System for Waste Heat Usage in Railway Vehicles

NASA Astrophysics Data System (ADS)

Wilbrecht, Sebastian; Beitelschmidt, Michael

2018-06-01

This work focuses on the conceptual design and optimization of a near series prototype of a high-power thermoelectric generator system (TEG system) for diesel-electric locomotives. The replacement of the silencer in the exhaust line enables integration with already existing vehicles. However, compliance with the technical and legal frameworks and the assembly space requirements is just as important as the limited exhaust back pressure, the high power density and the low life cycle costs. A special emphasis is given to the comparison of cascaded two-stage Bi2Te3 and Mg2Si0.4Sn0.6/MnSi1.81 modules with single-stage Bi2Te3 modules, both manufactured in lead-frame technology. In addition to the numerous, partly competing boundary conditions for the use in rail vehicles, the additional degree of freedom from the cascaded thermoelectric modules (TEM) is considered. The problem is investigated by coupling one-dimensional multi-domain simulations with an optimization framework using a genetic algorithm. The achievable electrical power of the single-stage system is significantly higher, at 3.2 kW, than the performance of the two-stage system (2.5 kW). Although the efficiency of the two-stage system is 44.2% higher than the single-stage system, the overall power output is 22.8% lower. This is because the lower power density and the lower number of TEM more than compensates the better efficiency. Hence, the available installation space, and thus the power density, is a critical constraint for the design of TEG systems. Furthermore, for applications recovering exhaust gas enthalpy, the large temperature drop across the heat exchanger is characteristic and must be considered carefully within the design process.

Discriminating cellular heterogeneity using microwell-based RNA cytometry

PubMed Central

Dimov, Ivan K.; Lu, Rong; Lee, Eric P.; Seita, Jun; Sahoo, Debashis; Park, Seung-min; Weissman, Irving L.; Lee, Luke P.

2014-01-01

Discriminating cellular heterogeneity is important for understanding cellular physiology. However, it is limited by the technical difficulties of single-cell measurements. Here, we develop a two-stage system to determine cellular heterogeneity. In the first stage, we perform multiplex single-cell RNA-cytometry in a microwell array containing over 60,000 reaction chambers. In the second stage, we use the RNA-cytometry data to determine cellular heterogeneity by providing a heterogeneity likelihood score. Moreover, we use Monte-Carlo simulation and RNA-cytometry data to calculate the minimum number of cells required for detecting heterogeneity. We applied this system to characterize the RNA distributions of aging related genes in a highly purified mouse hematopoietic stem cell population. We identified genes that reveal novel heterogeneity of these cells. We also show that changes in expression of genes such as Birc6 during aging can be attributed to the shift of relative portions of cells in the high-expressing subgroup versus low-expressing subgroup. PMID:24667995

Measured effects of coolant injection on the performance of a film cooled turbine

NASA Technical Reports Server (NTRS)

Mcdonel, J. D.; Eiswerth, J. E.

1977-01-01

Tests have been conducted on a 20-inch diameter single-stage air-cooled turbine designed to evaluate the effects of film cooling air on turbine aerodynamic performance. The present paper reports the results of five test configurations, including two different cooling designs and three combinations of cooled and solid airfoils. A comparison is made of the experimental results with a previously published analytical method of evaluating coolant injection effects on turbine performance.

Performance Validation Approach for the GTX Air-Breathing Launch Vehicle

NASA Technical Reports Server (NTRS)

Trefny, Charles J.; Roche, Joseph M.

2002-01-01

The primary objective of the GTX effort is to determine whether or not air-breathing propulsion can enable a launch vehicle to achieve orbit in a single stage. Structural weight, vehicle aerodynamics, and propulsion performance must be accurately known over the entire flight trajectory in order to make a credible assessment. Structural, aerodynamic, and propulsion parameters are strongly interdependent, which necessitates a system approach to design, evaluation, and optimization of a single-stage-to-orbit concept. The GTX reference vehicle serves this purpose, by allowing design, development, and validation of components and subsystems in a system context. The reference vehicle configuration (including propulsion) was carefully chosen so as to provide high potential for structural and volumetric efficiency, and to allow the high specific impulse of air-breathing propulsion cycles to be exploited. Minor evolution of the configuration has occurred as analytical and experimental results have become available. With this development process comes increasing validation of the weight and performance levels used in system performance determination. This paper presents an overview of the GTX reference vehicle and the approach to its performance validation. Subscale test rigs and numerical studies used to develop and validate component performance levels and unit structural weights are outlined. The sensitivity of the equivalent, effective specific impulse to key propulsion component efficiencies is presented. The role of flight demonstration in development and validation is discussed.

Cryogenic Boil-Off Reduction System

NASA Astrophysics Data System (ADS)

Plachta, David W.; Guzik, Monica C.

2014-03-01

A computational model of the cryogenic boil-off reduction system being developed by NASA as part of the Cryogenic Propellant Storage and Transfer technology maturation project has been applied to a range of propellant storage tanks sizes for high-performing in-space cryogenic propulsion applications. This effort focuses on the scaling of multi-layer insulation (MLI), cryocoolers, broad area cooling shields, radiators, solar arrays, and tanks for liquid hydrogen propellant storage tanks ranging from 2 to 10 m in diameter. Component scaling equations were incorporated into the Cryogenic Analysis Tool, a spreadsheet-based tool used to perform system-level parametric studies. The primary addition to the evolution of this updated tool is the integration of a scaling method for reverse turbo-Brayton cycle cryocoolers, as well as the development and inclusion of Self-Supporting Multi-Layer Insulation. Mass, power, and sizing relationships are traded parametrically to establish the appropriate loiter period beyond which this boil-off reduction system application reduces mass. The projected benefit compares passive thermal control to active thermal control, where active thermal control is evaluated for reduced boil-off with a 90 K shield, zero boil-off with a single heat interception stage at the tank wall, and zero boil-off with a second interception stage at a 90 K shield. Parametric studies show a benefit over passive storage at loiter durations under one month, in addition to showing a benefit for two-stage zero boil-off in terms of reducing power and mass as compared to single stage zero boil-off. Furthermore, active cooling reduces the effect of varied multi-layer insulation performance, which, historically, has been shown to be significant.

Use of skin stretchers for single-stage bilateral mastectomies in a dog and a cat.

PubMed

Miyazaki, Yuta; Aikawa, Takeshi; Shimatsu, Taichi; Nishimura, Masaaki; Sadahiro, Shigeo

2018-04-01

To describe the application of skin stretchers for closure of single-stage bilateral mastectomies in a dog and a cat. Clinical case report. A 12-year-old intact female Miniature Dachshund and a 13-year-old spayed female domestic short-hair cat. Skin stretchers were applied to the site of the skin adjacent to mammary glands for 2-4 days before surgery. Cable tension was adjusted every 6-8 hours to elongate the skin and to achieve primary closure of single-stage bilateral mastectomy without tension. Wound closure after single-stage bilateral mastectomy was achieved without tension or major complication in both animals. Use of skin stretchers allows primary closure of single-stage bilateral mastectomy in dogs and cats. © 2017 The American College of Veterinary Surgeons.

Reestablishment of an Unknown State and Its Orthogonal Complement State with Assistance

NASA Astrophysics Data System (ADS)

Chen, Ai-Xi; Wu, Shu-Dong

2003-12-01

In this paper, we propose a protocol where one can realize reestablishment of an unknown state and its orthogonal complement state with a certain probability. In the first stage of the protocol, teleportation is performed between Alice (a sender) and Bob (a receiver) through a nonmaximally entangled quantum channel. In the process of teleportation, Alice performs nonmaximally entangled state measurement. In the second stage of the protocol, Victor (a state preparer) disentangles leftover nonmaximally entangled states by a single-particle measurement. With the assistance of Victor Alice can reestablish the original state or produce its orthogonal state. The project partially supported by National Natural Science Foundation of China under Grant Nos. 90103026 and 60078023

Rotating stall investigation of 0.72 hub-tip ratio single-stage compressor

NASA Technical Reports Server (NTRS)

Graham, Robert W; Prian, Vasily D

1954-01-01

The rotating stall characteristics of a 0.72 hub-tip ratio, single-stage compressor were investigated. The stage was a 14-inch-diameter replica of the fourth stage of an experimental multistage compressor. No similarity existed between the frequency and propagation rate of the stall patterns observed in the single-stage replica and those observed in the multistage compressor after the fourth stage. A fatigue failure of the rotor blades occurred during the testing which was attributed to a resonance between the stall frequency and the natural bending frequency of the blades.

White blood cell differential count of maturation stages in bone marrow smear using dual-stage convolutional neural networks.

PubMed

Choi, Jin Woo; Ku, Yunseo; Yoo, Byeong Wook; Kim, Jung-Ah; Lee, Dong Soon; Chai, Young Jun; Kong, Hyoun-Joong; Kim, Hee Chan

2017-01-01

The white blood cell differential count of the bone marrow provides information concerning the distribution of immature and mature cells within maturation stages. The results of such examinations are important for the diagnosis of various diseases and for follow-up care after chemotherapy. However, manual, labor-intensive methods to determine the differential count lead to inter- and intra-variations among the results obtained by hematologists. Therefore, an automated system to conduct the white blood cell differential count is highly desirable, but several difficulties hinder progress. There are variations in the white blood cells of each maturation stage, small inter-class differences within each stage, and variations in images because of the different acquisition and staining processes. Moreover, a large number of classes need to be classified for bone marrow smear analysis, and the high density of touching cells in bone marrow smears renders difficult the segmentation of single cells, which is crucial to traditional image processing and machine learning. Few studies have attempted to discriminate bone marrow cells, and even these have either discriminated only a few classes or yielded insufficient performance. In this study, we propose an automated white blood cell differential counting system from bone marrow smear images using a dual-stage convolutional neural network (CNN). A total of 2,174 patch images were collected for training and testing. The dual-stage CNN classified images into 10 classes of the myeloid and erythroid maturation series, and achieved an accuracy of 97.06%, a precision of 97.13%, a recall of 97.06%, and an F-1 score of 97.1%. The proposed method not only showed high classification performance, but also successfully classified raw images without single cell segmentation and manual feature extraction by implementing CNN. Moreover, it demonstrated rotation and location invariance. These results highlight the promise of the proposed method as an automated white blood cell differential count system.

White blood cell differential count of maturation stages in bone marrow smear using dual-stage convolutional neural networks

PubMed Central

Choi, Jin Woo; Ku, Yunseo; Yoo, Byeong Wook; Kim, Jung-Ah; Lee, Dong Soon; Chai, Young Jun; Kong, Hyoun-Joong

2017-01-01

The white blood cell differential count of the bone marrow provides information concerning the distribution of immature and mature cells within maturation stages. The results of such examinations are important for the diagnosis of various diseases and for follow-up care after chemotherapy. However, manual, labor-intensive methods to determine the differential count lead to inter- and intra-variations among the results obtained by hematologists. Therefore, an automated system to conduct the white blood cell differential count is highly desirable, but several difficulties hinder progress. There are variations in the white blood cells of each maturation stage, small inter-class differences within each stage, and variations in images because of the different acquisition and staining processes. Moreover, a large number of classes need to be classified for bone marrow smear analysis, and the high density of touching cells in bone marrow smears renders difficult the segmentation of single cells, which is crucial to traditional image processing and machine learning. Few studies have attempted to discriminate bone marrow cells, and even these have either discriminated only a few classes or yielded insufficient performance. In this study, we propose an automated white blood cell differential counting system from bone marrow smear images using a dual-stage convolutional neural network (CNN). A total of 2,174 patch images were collected for training and testing. The dual-stage CNN classified images into 10 classes of the myeloid and erythroid maturation series, and achieved an accuracy of 97.06%, a precision of 97.13%, a recall of 97.06%, and an F-1 score of 97.1%. The proposed method not only showed high classification performance, but also successfully classified raw images without single cell segmentation and manual feature extraction by implementing CNN. Moreover, it demonstrated rotation and location invariance. These results highlight the promise of the proposed method as an automated white blood cell differential count system. PMID:29228051

Electromechanical actuation for cryogenic valve control

NASA Technical Reports Server (NTRS)

Lister, M. J.; Reichmuth, D. M.

1993-01-01

The design and analysis of the electromechanical actuator (EMA) being developed for the NASA/Marshall Space Flight Center as part of the National Launch System (NLS) Propellant Control Effector Advanced Development Program (ADP) are addressed. The EMA design uses several proven technologies combined into a single modular package which includes single stage high ratio gear reduction, redundant electric motors mounted on a common drive shaft, redundant drive and control electronics, and digital technology for performing the closed loop position feedback, communication, and health monitoring functions. Results of tests aimed at evaluating both component characteristics and overall system performance demonstrated that the goal of low cost, reliable control in a cryogenic environment is feasible.

Energy efficient engine high-pressure turbine detailed design report

NASA Technical Reports Server (NTRS)

Thulin, R. D.; Howe, D. C.; Singer, I. D.

1982-01-01

The energy efficient engine high-pressure turbine is a single stage system based on technology advancements in the areas of aerodynamics, structures and materials to achieve high performance, low operating economics and durability commensurate with commercial service requirements. Low loss performance features combined with a low through-flow velocity approach results in a predicted efficiency of 88.8 for a flight propulsion system. Turbine airfoil durability goals are achieved through the use of advanced high-strength and high-temperature capability single crystal materials and effective cooling management. Overall, this design reflects a considerable extension in turbine technology that is applicable to future, energy efficient gas-turbine engines.

Single-Mode Deceleration Stage Rayleigh-Taylor Instability Growth in Cylindrical Implosions

NASA Astrophysics Data System (ADS)

Sauppe, J. P.; Palaniyappan, S.; Bradley, P. A.; Batha, S. H.; Loomis, E. N.; Kline, J. L.; Srinivasan, B.; Bose, A.; Malka, E.; Shvarts, D.

2017-10-01

We present design calculations demonstrating the feasibility of measuring single-mode deceleration stage Rayleigh-Taylor instability (RTI) growth at a factor of four convergence. RTI growth rates are modified as a result of convergence [Bell LA-1321, 1951], and cylindrical targets are considered here, as they allow direct diagnostic access along the interface. The 2D computations, performed with the radiation-hydrodynamics code xRAGE [Gittings et al., CSD 2008] utilizing a new laser ray-tracing package, predict growth factors of 6 to 10 for mode 10 and 4 to 6 for mode 4, both of high interest in evaluating inertial confinement fusion capsule degradation mechanisms [Bose et al., this conference]. These results compare favorably to a linear theory [Epstein, PoP 2004] and to a buoyancy-drag model [Srebro et al., LPB 2003], which accounts for the linear and non-linear stages. Synthetic radiographs, produced by combining 2D computations of axial and transverse cross-sections, indicate this growth will be observable, and these will be compared to experimental data obtained at the OMEGA laser facility. Work performed by Los Alamos National Laboratory under contract DE-AC52-06NA25396 for the National Nuclear Security Administration of the U.S. Department of Energy. (LA-UR-17-25608).

Effects of perforation number of blade on aerodynamic performance of dual-rotor small axial flow fans

NASA Astrophysics Data System (ADS)

Hu, Yongjun; Wang, Yanping; Li, Guoqi; Jin, Yingzi; Setoguchi, Toshiaki; Kim, Heuy Dong

2015-04-01

Compared with single rotor small axial flow fans, dual-rotor small axial flow fans is better regarding the static characteristics. But the aerodynamic noise of dual-rotor small axial flow fans is worse than that of single rotor small axial flow fans. In order to improve aerodynamic noise of dual-rotor small axial flow fans, the pre-stage blades with different perforation numbers are designed in this research. The RANS equations and the standard k-ɛ turbulence model as well as the FW-H noise model are used to simulate the flow field within the fan. Then, the aerodynamic performance of the fans with different perforation number is compared and analyzed. The results show that: (1) Compared to the prototype fan, the noise of fans with perforation blades is reduced. Additionally, the noise of the fans decreases with the increase of the number of perforations. (2) The vorticity value in the trailing edge of the pre-stage blades of perforated fans is reduced. It is found that the vorticity value in the trailing edge of the pre-stage blades decreases with the increase of the number of perforations. (3) Compared to the prototype fan, the total pressure rising and efficiency of the fans with perforation blades drop slightly.

Single-stage-to-orbit performance enhancement from take-off thrust augmentation

NASA Astrophysics Data System (ADS)

Galati, Terence; Elkins, Travis

1997-01-01

Thrust augmentation offers the Single Stage to Orbit (SSTO) space launch vehicle improved payload capability while reducing vehicle weight and cost. Optimization of vehicle configuration and flight profile are studied. Using a 612,000 kg Gross Lift Off Weight (GLOW) SSTO with three Castor® strap-on motors, payloads in excess of 18,000 kg to Low Earth Orbit (LEO) are achievable. Emphasis is placed on finding vehicle optimums in the 9,000 kg payload range to capture over 80% of commercial payloads. Strap-on boosters allow a small SSTO vehicle to fly with a mass fraction of only 0.88 and LOX/H2 engines operating at 445 sec vacuum specific impulse. Payload sensitivity due to variations of mass fraction, Isp and pitch rate are quantified.

Improving Functional and Aesthetic Outcomes in Syndromic Patients With Webbed Neck Deformity: Utilizing a Staged Endoscopic-Assisted Approach to Improve the Posterior Hairline and Decrease Scar Burden.

PubMed

Van Kouwenberg, Emily; Chattha, Anmol S; Adetayo, Oluwaseun A

2017-06-01

Webbed neck deformity (WND) can have significant functional and psychosocial impact on the developing child. Surgical correction can be challenging depending on the extent of the deformity, and patients often also have low posterior hairlines requiring simultaneous correction. Current surgical techniques include various methods of single-stage radical excision that often result in visible scar burden and residual deformity. There is currently no general consensus of which technique provides the best outcomes. A modified approach to WND was designed by the senior author aimed to decrease scar burden. Endoscopic-assisted fasciectomy was performed with simultaneous posterior hairline reconstruction with local tissue rearrangement camouflaged within the hair-bearing scalp. Staged surgical correction was planned rather than correction in a single operation. A retrospective review was performed to evaluate all patients who underwent this approach over a 2-year period. Two patients underwent the modified approach, a 17-year-old female with Noonan syndrome and a 2-year-old female with Turner syndrome. Both patients showed postoperative improvement in range of motion, contour of the jaw and neckline, and posterior hairline definition. Patients were found to have decreased scar burden compared with traditional techniques. A staged, combination approach of endoscopic-assisted fasciectomy and strategic local tissue reconstruction of the posterior hairline to correct WND achieves good functional and aesthetic results and good patient satisfaction. This modification should be considered when managing WND.

A two-dimensional biased coin design for dual-agent dose-finding trials.

PubMed

Sun, Zhichao; Braun, Thomas M

2015-12-01

Given the limited efficacy observed with single agents, there is growing interest in Phase I clinical trial designs that allow for identification of the maximum tolerated combination of two agents. Existing parametric designs may suffer from over- or under-parameterization. Thus, we have designed a nonparametric approach that can be easily understood and implemented for combination trials. We propose a two-stage adaptive biased coin design that extends existing methods for single-agent trials to dual-agent dose-finding trials. The basic idea of our design is to divide the entire trial into two stages and apply the biased coin design, with modification, in each stage. We compare the operating characteristics of our design to four competing parametric approaches via simulation in several numerical examples. Under all simulation scenarios we have examined, our method performs well in terms of identification of the maximum tolerated combination and allocation of patients relative to the performance of its competitors. In our design, stopping rule criteria and the distribution of the total sample size among the two stages are context-dependent, and both need careful consideration before adopting our design in practice. Efficacy is not a part of the dose-assignment algorithm, nor used to define the maximum tolerated combination. Our design inherits the favorable statistical properties of the biased coin design, is competitive with existing designs, and promotes patient safety by limiting patient exposure to toxic combinations whenever possible. © The Author(s) 2015.

Analysis of honeybush tea (Cyclopia spp.) volatiles by comprehensive two-dimensional gas chromatography using a single-stage thermal modulator.

PubMed

Ntlhokwe, Gaalebalwe; Tredoux, Andreas G J; Górecki, Tadeusz; Edwards, Matthew; Vestner, Jochen; Muller, Magdalena; Erasmus, Lené; Joubert, Elizabeth; Christel Cronje, J; de Villiers, André

2017-07-01

The applicability of comprehensive two-dimensional gas chromatography (GC×GC) using a single-stage thermal modulator was explored for the analysis of honeybush tea (Cyclopia spp.) volatile compounds. Headspace solid phase micro-extraction (HS-SPME) was used in combination with GC×GC separation on a non-polar × polar column set with flame ionisation (FID) detection for the analysis of fermented Cyclopia maculata, Cyclopia subternata and Cyclopia genistoides tea infusions of a single harvest season. Method optimisation entailed evaluation of the effects of several experimental parameters on the performance of the modulator, the choice of columns in both dimensions, as well as the HS-SPME extraction fibre. Eighty-four volatile compounds were identified by co-injection of reference standards. Principal component analysis (PCA) showed clear differentiation between the species based on their volatile profiles. Due to the highly reproducible separations obtained using the single-stage thermal modulator, multivariate data analysis was simplified. The results demonstrate both the complexity of honeybush volatile profiles and the potential of GC×GC separation in combination with suitable data analysis techniques for the investigation of the relationship between sensory properties and volatile composition of these products. The developed method therefore offers a fast and inexpensive methodology for the profiling of honeybush tea volatiles. Graphical abstract Surface plot obtained for the GC×GC-FID analysis of honeybush tea volatiles.

Injection blow moulding single stage process: Validation of the numerical simulation through tomography analysis

NASA Astrophysics Data System (ADS)

Biglione, Jordan; Béreaux, Yves; Charmeau, Jean-Yves

2016-10-01

The injection blow moulding single stage process has been made available on standard injection moulding machine. Both the injection moulding stage and the blow moulding stage are being taken care of in an injection mould. Thus the dimensions of this mould are those of a conventional injection moulding mould. The fact that the two stages are located in the same mould leads to a process more constrained than the conventional one. This process introduces temperature gradients, molecular orientation, high stretch rates and high cooling rates. These constraints lead to a small processing window. In practice, the preform has to remain sufficiently melted to be blown so that the process takes place between the melting temperature and the crystallization temperature. In our numerical approach, the polymer is supposed to be blown in its molten state. Hence we have identified the mechanical behaviour of the polymer in its molten state through dynamical rheology experiments. A viscous Cross model has been proved to be relevant to the problem. Thermal dependence is assumed by an Arrhenius law. The process is simulated through a finite element code (POLYFLOW software) in the Ansys Workbench framework. Thickness measurements using image analysis of tomography data are performed and comparisons with the simulation results show good agreements.

Lifetime test and heritage on orbit of coolers for space use

NASA Astrophysics Data System (ADS)

Narasaki, Katsuhiro; Tsunematsu, Shoji; Ootsuka, Kiyomi; Kanao, Kenichi; Okabayashi, Akinobu; Mitsuda, Kazuhisa; Murakami, Hiroshi; Nakagawa, Takao; Kikuchi, Kenichi; Sato, Ryota; Sugita, Hiroyuki; Sato, Youichi; Murakami, Masahide; Kobayashi, Masanori

2012-04-01

This report describes the results and operating status of ground lifetime testing and achievements on orbit of coolers for space use. Ground lifetime tests of coolers of three types were conducted to demonstrate their long life and reliability. Three single-stage Stirling coolers were tested for 89,016, 71,871 and 68,273 h from 1998, a two-stage Stirling cooler was tested for 72,906 h, and a 4-K class cooler with a two-stage Stirling cooler and a Joule-Thomson cooler was tested for over 2.5 years. After lifetime tests were completed, a few coolers were investigated to determine the cause of the cooling performance degradation. Additionally, the filled gas of the coolers was analyzed. These coolers have shown good results on orbit. Three single-stage Stirling coolers were carried on the X-ray astronomical satellite "SUZAKU" (launched in July 2005), Japanese lunar polar orbiter "KAGUYA" (launched in September 2007), and the Japanese Venus Climate Orbiter "AKATSUKI" (launched in June 2010). Two units of a two-stage Stirling cooler were carried on the infrared astronomical satellite "AKARI" launched in February 2006. A 4-K class cooler was carried on the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) aboard the Japanese Experiment Module (JEM) of the International Space Station (ISS). SMILES was launched in September 2009.

Hybrid maize breeding with doubled haploids: II. Optimum type and number of testers in two-stage selection for general combining ability.

PubMed

Longin, C Friedrich H; Utz, H Friedrich; Melchinger, Albrecht E; Reif, Jochen C

2007-02-01

Optimum allocation of test resources is of crucial importance for the efficiency of breeding programs. Our objectives were to (1) determine the optimum allocation of the number of lines, test locations, as well as number and type of testers in hybrid maize breeding using doubled haploids with two breeding strategies for improvement of general combining ability (GCA), (2) compare the maximum selection gain (DeltaG) achievable under both strategies, and (3) give recommendations for the optimum implementation of doubled haploids in commercial hybrid maize breeding. We calculated DeltaG by numerical integration for two two-stage selection strategies with evaluation of (1) testcross performance in both stages (BS1) or (2) line per se performance in the first stage followed by testcross performance in the second stage (BS2). Different assumptions were made regarding the budget, variance components (VCs), and the correlation between line per se performance and GCA. Selection gain for GCA increased with a broader genetic base of the tester. Hence, testers combining a large number of divergent lines are advantageous. However, in applied breeding programs, the use of single- or double-cross testers in the first and inbred testers in the second selection stage may be a good compromise between theoretical and practical requirements. With a correlation between line per se performance and GCA of 0.50, DeltaG for BS1 is about 5% higher than for BS2, if an economic weight of line per se performance is neglected. With increasing economic weight of line per se performance, relative efficiency of BS2 increased rapidly resulting in a superiority of BS2 over BS1 already for an economic weight for line per se performance larger than 0.1. Considering the importance of an economic seed production, an economic weight larger than 0.1 seems realistic indicating the necessity of separate breeding strategies for seed and pollen parent heterotic groups.

Digital Microwave System Design Guide.

DTIC Science & Technology

1984-02-01

traffic analysis is a continuous effort, setting parameters for subsequent stages of expansion after the system design is finished. 2.1.3 Quality of...operational structure of the user for whom he is providing service. 2.2.3 Quality of Service. In digital communications, the basic performance parameter ...the basic interpretation of system performance is measured in terms of a single parameter , throughput. Throughput can be defined as the number of

Evaluation of single and two-stage adaptive sampling designs for estimation of density and abundance of freshwater mussels in a large river

USGS Publications Warehouse

Smith, D.R.; Rogala, J.T.; Gray, B.R.; Zigler, S.J.; Newton, T.J.

2011-01-01

Reliable estimates of abundance are needed to assess consequences of proposed habitat restoration and enhancement projects on freshwater mussels in the Upper Mississippi River (UMR). Although there is general guidance on sampling techniques for population assessment of freshwater mussels, the actual performance of sampling designs can depend critically on the population density and spatial distribution at the project site. To evaluate various sampling designs, we simulated sampling of populations, which varied in density and degree of spatial clustering. Because of logistics and costs of large river sampling and spatial clustering of freshwater mussels, we focused on adaptive and non-adaptive versions of single and two-stage sampling. The candidate designs performed similarly in terms of precision (CV) and probability of species detection for fixed sample size. Both CV and species detection were determined largely by density, spatial distribution and sample size. However, designs did differ in the rate that occupied quadrats were encountered. Occupied units had a higher probability of selection using adaptive designs than conventional designs. We used two measures of cost: sample size (i.e. number of quadrats) and distance travelled between the quadrats. Adaptive and two-stage designs tended to reduce distance between sampling units, and thus performed better when distance travelled was considered. Based on the comparisons, we provide general recommendations on the sampling designs for the freshwater mussels in the UMR, and presumably other large rivers.

Vibration-based angular speed estimation for multi-stage wind turbine gearboxes

NASA Astrophysics Data System (ADS)

Peeters, Cédric; Leclère, Quentin; Antoni, Jérôme; Guillaume, Patrick; Helsen, Jan

2017-05-01

Most processing tools based on frequency analysis of vibration signals are only applicable for stationary speed regimes. Speed variation causes the spectral content to smear, which encumbers most conventional fault detection techniques. To solve the problem of non-stationary speed conditions, the instantaneous angular speed (IAS) is estimated. Wind turbine gearboxes however are typically multi-stage gearboxes, consisting of multiple shafts, rotating at different speeds. Fitting a sensor (e.g. a tachometer) to every single stage is not always feasible. As such there is a need to estimate the IAS of every single shaft based on the vibration signals measured by the accelerometers. This paper investigates the performance of the multi-order probabilistic approach for IAS estimation on experimental case studies of wind turbines. This method takes into account the meshing orders of the gears present in the system and has the advantage that a priori it is not necessary to associate harmonics with a certain periodic mechanical event, which increases the robustness of the method. It is found that the MOPA has the potential to easily outperform standard band-pass filtering techniques for speed estimation. More knowledge of the gearbox kinematics is beneficial for the MOPA performance, but even with very little knowledge about the meshing orders, the MOPA still performs sufficiently well to compete with the standard speed estimation techniques. This observation is proven on two different data sets, both originating from vibration measurements on the gearbox housing of a wind turbine.

Automatic sleep stage classification of single-channel EEG by using complex-valued convolutional neural network.

PubMed

Zhang, Junming; Wu, Yan

2018-03-28

Many systems are developed for automatic sleep stage classification. However, nearly all models are based on handcrafted features. Because of the large feature space, there are so many features that feature selection should be used. Meanwhile, designing handcrafted features is a difficult and time-consuming task because the feature designing needs domain knowledge of experienced experts. Results vary when different sets of features are chosen to identify sleep stages. Additionally, many features that we may be unaware of exist. However, these features may be important for sleep stage classification. Therefore, a new sleep stage classification system, which is based on the complex-valued convolutional neural network (CCNN), is proposed in this study. Unlike the existing sleep stage methods, our method can automatically extract features from raw electroencephalography data and then classify sleep stage based on the learned features. Additionally, we also prove that the decision boundaries for the real and imaginary parts of a complex-valued convolutional neuron intersect orthogonally. The classification performances of handcrafted features are compared with those of learned features via CCNN. Experimental results show that the proposed method is comparable to the existing methods. CCNN obtains a better classification performance and considerably faster convergence speed than convolutional neural network. Experimental results also show that the proposed method is a useful decision-support tool for automatic sleep stage classification.

Sub-classification of Advanced-Stage Hepatocellular Carcinoma: A Cohort Study Including 612 Patients Treated with Sorafenib.

PubMed

Yoo, Jeong-Ju; Chung, Goh Eun; Lee, Jeong-Hoon; Nam, Joon Yeul; Chang, Young; Lee, Jeong Min; Lee, Dong Ho; Kim, Hwi Young; Cho, Eun Ju; Yu, Su Jong; Kim, Yoon Jun; Yoon, Jung-Hwan

2018-04-01

Advanced hepatocellular carcinoma (HCC) is associated with various clinical conditions including major vessel invasion, metastasis, and poor performance status. The aim of this study was to establish a prognostic scoring system and to propose a sub-classification of the Barcelona-Clinic Liver Cancer (BCLC) stage C. This retrospective study included consecutive patientswho received sorafenib for BCLC stage C HCC at a single tertiary hospital in Korea. A Cox proportional hazard model was used to develop a scoring system, and internal validationwas performed by a 5-fold cross-validation. The performance of the model in predicting risk was assessed by the area under the curve and the Hosmer-Lemeshow test. A total of 612 BCLC stage C HCC patients were sub- classified into strata depending on their performance status. Five independent prognostic factors (Child-Pugh score, α-fetoprotein, tumor type, extrahepatic metastasis, and portal vein invasion) were identified and used in the prognostic scoring system. This scoring system showed good discrimination (area under the receiver operating characteristic curve, 0.734 to 0.818) and calibration functions (both p < 0.05 by the Hosmer-Lemeshow test at 1 month and 12 months, respectively). The differences in survival among the different risk groups classified by the total score were significant (p < 0.001 by the log-rank test in both the Eastern Cooperative Oncology Group 0 and 1 strata). The heterogeneity of patientswith BCLC stage C HCC requires sub-classification of advanced HCC. A prognostic scoring system with five independent factors is useful in predicting the survival of patients with BCLC stage C HCC.

Evaluation of an intelligent wheelchair system for older adults with cognitive impairments

PubMed Central

2013-01-01

Background Older adults are the most prevalent wheelchair users in Canada. Yet, cognitive impairments may prevent an older adult from being allowed to use a powered wheelchair due to safety and usability concerns. To address this issue, an add-on Intelligent Wheelchair System (IWS) was developed to help older adults with cognitive impairments drive a powered wheelchair safely and effectively. When attached to a powered wheelchair, the IWS adds a vision-based anti-collision feature that prevents the wheelchair from hitting obstacles and a navigation assistance feature that plays audio prompts to help users manoeuvre around obstacles. Methods A two stage evaluation was conducted to test the efficacy of the IWS. Stage One: Environment of Use – the IWS’s anti-collision and navigation features were evaluated against objects found in a long-term care facility. Six different collision scenarios (wall, walker, cane, no object, moving and stationary person) and three different navigation scenarios (object on left, object on right, and no object) were performed. Signal detection theory was used to categorize the response of the system in each scenario. Stage Two: User Trials – single-subject research design was used to evaluate the impact of the IWS on older adults with cognitive impairment. Participants were asked to drive a powered wheelchair through a structured obstacle course in two phases: 1) with the IWS and 2) without the IWS. Measurements of safety and usability were taken and compared between the two phases. Visual analysis and phase averages were used to analyze the single-subject data. Results Stage One: The IWS performed correctly for all environmental anti-collision and navigation scenarios. Stage Two: Two participants completed the trials. The IWS was able to limit the number of collisions that occurred with a powered wheelchair and lower the perceived workload for driving a powered wheelchair. However, the objective performance (time to complete course) of users navigating their environment did not improve with the IWS. Conclusions This study shows the efficacy of the IWS in performing with a potential environment of use, and benefiting members of its desired user population to increase safety and lower perceived demands of powered wheelchair driving. PMID:23924489

Single-stage three-phase boost power factor correction circuit for AC-DC converter

NASA Astrophysics Data System (ADS)

Azazi, Haitham Z.; Ahmed, Sayed M.; Lashine, Azza E.

2018-01-01

This article presents a single-stage three-phase power factor correction (PFC) circuit for AC-to-DC converter using a single-switch boost regulator, leading to improve the input power factor (PF), reducing the input current harmonics and decreasing the number of required active switches. A novel PFC control strategy which is characterised as a simple and low-cost control circuit was adopted, for achieving a good dynamic performance, unity input PF, and minimising the harmonic contents of the input current, at which it can be applied to low/medium power converters. A detailed analytical, simulation and experimental studies were therefore conducted. The effectiveness of the proposed controller algorithm is validated by the simulation results, which were carried out using MATLAB/SIMULINK environment. The proposed system is built and tested in the laboratory using DSP-DS1104 digital control board for an inductive load. The results revealed that the total harmonic distortion in the supply current was very low. Finally, a good agreement between simulation and experimental results was achieved.

A method for determining optimum phasing of a multiphase propulsion system for a single-stage vehicle with linearized inert weight

NASA Technical Reports Server (NTRS)

Martin, J. A.

1974-01-01

A general analytical treatment is presented of a single-stage vehicle with multiple propulsion phases. A closed-form solution for the cost and for the performance and a derivation of the optimal phasing of the propulsion are included. Linearized variations in the inert weight elements are included, and the function to be minimized can be selected. The derivation of optimal phasing results in a set of nonlinear algebraic equations for optimal fuel volumes, for which a solution method is outlined. Three specific example cases are analyzed: minimum gross lift-off weight, minimum inert weight, and a minimized general function for a two-phase vehicle. The results for the two-phase vehicle are applied to the dual-fuel rocket. Comparisons with single-fuel vehicles indicate that dual-fuel vehicles can have lower inert weight either by development of a dual-fuel engine or by parallel burning of separate engines from lift-off.

Hemodynamic consequences of LPA stenosis in single ventricle stage 2 LPN circulation with automatic registration

NASA Astrophysics Data System (ADS)

Schiavazzi, Daniele E.; Kung, Ethan O.; Dorfman, Adam L.; Hsia, Tain-Yen; Baretta, Alessia; Arbia, Gregory; Marsden, Alison L.

2013-11-01

Congenital heart diseases such as hypoplastic left heart syndrome annually affect about 3% of births in the US alone. Surgical palliation of single ventricle patients is performed in stages. Consequently to the stage 2 surgical procedure or other previous conditions, a stenosis of the left pulmonary artery (LPA) is often observed, raising the clinical question of whether or not it should be treated. The severity of stenoses are commonly assessed through geometric inspection or catheter in-vivo pressure measurements with limited quantitative information about patient-specific physiology. The present study uses a multiscale CFD approach to provide an assessment of the severity of LPA stenoses. A lumped parameter 0D model is used to simulate stage 2 circulation, and parameters are automatically identified accounting for uncertainty in the clinical data available for a cohort of patients. The importance of the latter parameters, whether alone or in groups, is also ranked using forward uncertainty propagation methods. Various stenosis levels are applied to the three-dimensional SVC-PA junction model using a dual mesh-morphing approach. Traditional assessments methodologies are compared to the results of our findings and critically discussed.

Design study and performance analysis of a high-speed multistage variable-geometry fan for a variable cycle engine

NASA Technical Reports Server (NTRS)

Sullivan, T. J.; Parker, D. E.

1979-01-01

A design technology study was performed to identify a high speed, multistage, variable geometry fan configuration capable of achieving wide flow modulation with near optimum efficiency at the important operating condition. A parametric screening study of the front and rear block fans was conducted in which the influence of major fan design features on weight and efficiency was determined. Key design parameters were varied systematically to determine the fan configuration most suited for a double bypass, variable cycle engine. Two and three stage fans were considered for the front block. A single stage, core driven fan was studied for the rear block. Variable geometry concepts were evaluated to provide near optimum off design performance. A detailed aerodynamic design and a preliminary mechanical design were carried out for the selected fan configuration. Performance predictions were made for the front and rear block fans.

Empirical modeling of Single-Event Upset (SEU) in NMOS depletion-mode-load static RAM (SRAM) chips

NASA Technical Reports Server (NTRS)

Zoutendyk, J. A.; Smith, L. S.; Soli, G. A.; Smith, S. L.; Atwood, G. E.

1986-01-01

A detailed experimental investigation of single-event upset (SEU) in static RAM (SRAM) chips fabricated using a family of high-performance NMOS (HMOS) depletion-mode-load process technologies, has been done. Empirical SEU models have been developed with the aid of heavy-ion data obtained with a three-stage tandem van de Graaff accelerator. The results of this work demonstrate a method by which SEU may be empirically modeled in NMOS integrated circuits.

Robotic planetary science missions enabled with small NTR engine/stage technologies

NASA Astrophysics Data System (ADS)

Borowski, Stanley K.

1995-10-01

The high specific impulse (Isp) and engine thrust-to-weight ratio of liquid hydrogen (LH2)-cooled nuclear thermal rocket (NTR) engines makes them ideal for upper stage applications to difficult robotic planetary science missions. A small 15 thousand pound force (klbf) NTR engine using a uranium-zirconium-niobium 'ternary carbide' fuel (Isp approximately 960 seconds at approximately 3025K) developed in the Commonwealth of Independent States (CIS) is examined and its use on an expendable injection stage is shown to provide major increases in payload delivered to the outer planets (Saturn, Uranus, Neptune and Pluto). Using a single 'Titan IV-class' launch vehicle, with a lift capability to low Earth orbit (LEO) of approximately 20 metric tons (t), an expendable NTR upper stage can inject two Pluto 'Fast Flyby' spacecraft (PFF/SC) plus support equipment-combined mass of approximately 508 kg--on high energy, '6.5-9.2 year' direct trajectory missions to Pluto. A conventional chemical propulsion mission would use a liquid oxygen (LOX)/LH2 'Centaur' upper stage and two solid rocket 'kick motors' to inject a single PFF/SC on the same Titan IV launch vehicle. For follow on Pluto missions, the NTR injection stage would utilize a Jupiter 'gravity assist' (JGA) maneuver to launch a LOX/liquid methane (CH4) capture stage (Isp approximately 375 seconds) and a Pluto 'orbiter' spacecraft weighing between approximately 167-312 kg. With chemical propulsion, a Pluto orbiter mission is not a viable option because c inadequate delivered mass. Using a 'standardized' NTR injection stage and the same single Titan IV launch scenario, 'direct flight' (no gravity assist) orbiter missions to Saturn, Uranus and Neptune are also enabled with transit times of 2.3, 6.6, and 12.6 years, respectively. Injected mass includes a storable, nitrogen tetroxide/monomethyl hydrazine (N2O4/MMH) capture stage (Isp approximately 330 seconds) and orbiter payloads 340 to 820% larger than that achievable using a LOX/LH2-fueled injection stage. The paper discusses NTR technology and mission characteristics, shows NTR stage and payload accommodations within the 26.2 m long Titan IV payload fairing, and discusses NTR stage performance as a function of assumed cryogenic tank technology.

Robotic Planetary Science Missions Enabled with Small NTR Engine/Stage Technologies

NASA Technical Reports Server (NTRS)

Borowski, Stanley K.

1995-01-01

The high specific impulse (Isp) and engine thrust-to-weight ratio of liquid hydrogen (LH2)-cooled nuclear thermal rocket (NTR) engines makes them ideal for upper stage applications to difficult robotic planetary science missions. A small 15 thousand pound force (klbf) NTR engine using a uranium-zirconium-niobium 'ternary carbide' fuel (Isp approximately 960 seconds at approximately 3025K) developed in the Commonwealth of Independent States (CIS) is examined and its use on an expendable injection stage is shown to provide major increases in payload delivered to the outer planets (Saturn, Uranus, Neptune and Pluto). Using a single 'Titan IV-class' launch vehicle, with a lift capability to low Earth orbit (LEO) of approximately 20 metric tons (t), an expendable NTR upper stage can inject two Pluto 'Fast Flyby' spacecraft (PFF/SC) plus support equipment-combined mass of approximately 508 kg--on high energy, '6.5-9.2 year' direct trajectory missions to Pluto. A conventional chemical propulsion mission would use a liquid oxygen (LOX)/LH2 'Centaur' upper stage and two solid rocket 'kick motors' to inject a single PFF/SC on the same Titan IV launch vehicle. For follow on Pluto missions, the NTR injection stage would utilize a Jupiter 'gravity assist' (JGA) maneuver to launch a LOX/liquid methane (CH4) capture stage (Isp approximately 375 seconds) and a Pluto 'orbiter' spacecraft weighing between approximately 167-312 kg. With chemical propulsion, a Pluto orbiter mission is not a viable option because c inadequate delivered mass. Using a 'standardized' NTR injection stage and the same single Titan IV launch scenario, 'direct flight' (no gravity assist) orbiter missions to Saturn, Uranus and Neptune are also enabled with transit times of 2.3, 6.6, and 12.6 years, respectively. Injected mass includes a storable, nitrogen tetroxide/monomethyl hydrazine (N2O4/MMH) capture stage (Isp approximately 330 seconds) and orbiter payloads 340 to 820% larger than that achievable using a LOX/LH2-fueled injection stage. The paper discusses NTR technology and mission characteristics, shows NTR stage and payload accommodations within the 26.2 m long Titan IV payload fairing, and discusses NTR stage performance as a function of assumed cryogenic tank technology.

Cold-air performance of a 12.766-centimeter-tip-diameter axial-flow cooled turbine. 1: Design and performance of a solid blade configuration

NASA Technical Reports Server (NTRS)

Haas, J. E.; Kofskey, M. G.

1975-01-01

A solid blade version of a single-stage, axial-flow turbine was investigated to determine its performance over a range of speeds from 0 to 105 percent of equivalent design speed and over a range of total to static pressure ratios from 1.62 to 5.07. The results of this investigation will be used as a baseline for comparison with those obtained from a cooled version of this turbine.

V/STOL model fan stage rig design report

NASA Technical Reports Server (NTRS)

Cheatham, J. G.; Creason, T. L.

1983-01-01

A model single-stage fan with variable inlet guide vanes (VIGV) was designed to demonstrate efficient point operation while providing flow and pressure ratio modulation capability required for a V/STOL propulsion system. The fan stage incorporates a split-flap VIGV with an independently actuated ID flap to permit independent modulation of fan and core engine airstreams, a flow splitter integrally designed into the blade and vanes to completely segregate fan and core airstreams in order to maximize core stream supercharging for V/STOL operation, and an EGV with a variable leading edge fan flap for rig performance optimization. The stage was designed for a maximum flow size of 37.4 kg/s (82.3 lb/s) for compatibility with LeRC test facility requirements. Design values at maximum flow for blade tip velocity and stage pressure ratio are 472 m/s (1550 ft/s) and 1.68, respectively.

Stages as models of scene geometry.

PubMed

Nedović, Vladimir; Smeulders, Arnold W M; Redert, André; Geusebroek, Jan-Mark

2010-09-01

Reconstruction of 3D scene geometry is an important element for scene understanding, autonomous vehicle and robot navigation, image retrieval, and 3D television. We propose accounting for the inherent structure of the visual world when trying to solve the scene reconstruction problem. Consequently, we identify geometric scene categorization as the first step toward robust and efficient depth estimation from single images. We introduce 15 typical 3D scene geometries called stages, each with a unique depth profile, which roughly correspond to a large majority of broadcast video frames. Stage information serves as a first approximation of global depth, narrowing down the search space in depth estimation and object localization. We propose different sets of low-level features for depth estimation, and perform stage classification on two diverse data sets of television broadcasts. Classification results demonstrate that stages can often be efficiently learned from low-dimensional image representations.

Estimating rice yield related traits and quantitative trait loci analysis under different nitrogen treatments using a simple tower-based field phenotyping system with modified single-lens reflex cameras

NASA Astrophysics Data System (ADS)

Naito, Hiroki; Ogawa, Satoshi; Valencia, Milton Orlando; Mohri, Hiroki; Urano, Yutaka; Hosoi, Fumiki; Shimizu, Yo; Chavez, Alba Lucia; Ishitani, Manabu; Selvaraj, Michael Gomez; Omasa, Kenji

2017-03-01

Application of field based high-throughput phenotyping (FB-HTP) methods for monitoring plant performance in real field conditions has a high potential to accelerate the breeding process. In this paper, we discuss the use of a simple tower based remote sensing platform using modified single-lens reflex cameras for phenotyping yield traits in rice under different nitrogen (N) treatments over three years. This tower based phenotyping platform has the advantages of simplicity, ease and stability in terms of introduction, maintenance and continual operation under field conditions. Out of six phenological stages of rice analyzed, the flowering stage was the most useful in the estimation of yield performance under field conditions. We found a high correlation between several vegetation indices (simple ratio (SR), normalized difference vegetation index (NDVI), transformed vegetation index (TVI), corrected transformed vegetation index (CTVI), soil-adjusted vegetation index (SAVI) and modified soil-adjusted vegetation index (MSAVI)) and multiple yield traits (panicle number, grain weight and shoot biomass) across a three trials. Among all of the indices studied, SR exhibited the best performance in regards to the estimation of grain weight (R2 = 0.80). Under our tower-based field phenotyping system (TBFPS), we identified quantitative trait loci (QTL) for yield related traits using a mapping population of chromosome segment substitution lines (CSSLs) and a single nucleotide polymorphism data set. Our findings suggest the TBFPS can be useful for the estimation of yield performance during early crop development. This can be a major opportunity for rice breeders whom desire high throughput phenotypic selection for yield performance traits.

Strategies for enhanced deammonification performance and reduced nitrous oxide emissions.

PubMed

Leix, Carmen; Drewes, Jörg E; Ye, Liu; Koch, Konrad

2017-07-01

Deammonification's performance and associated nitrous oxide emissions (N 2 O) depend on operational conditions. While studies have investigated factors for high performances and low emissions separately, this study investigated optimizing deammonification performance while simultaneously reducing N 2 O emissions. Using a design of experiment (DoE) method, two models were developed for the prediction of the nitrogen removal rate and N 2 O emissions during single-stage deammonification considering three operational factors (i.e., pH value, feeding and aeration strategy). The emission factor varied between 0.7±0.5% and 4.1±1.2% at different DoE-conditions. The nitrogen removal rate was predicted to be maximized at settings of pH 7.46, intermittent feeding and aeration. Conversely, emissions were predicted to be minimized at the design edges at pH 7.80, single feeding, and continuous aeration. Results suggested a weak positive correlation between the nitrogen removal rate and N 2 O emissions, thus, a single optimizing operational set-point for maximized performance and minimized emissions did not exist. Copyright © 2017 Elsevier Ltd. All rights reserved.

Oligonucleotide arrays vs. metaphase-comparative genomic hybridisation and BAC arrays for single-cell analysis: first applications to preimplantation genetic diagnosis for Robertsonian translocation carriers.

PubMed

Ramos, Laia; del Rey, Javier; Daina, Gemma; García-Aragonés, Manel; Armengol, Lluís; Fernandez-Encinas, Alba; Parriego, Mònica; Boada, Montserrat; Martinez-Passarell, Olga; Martorell, Maria Rosa; Casagran, Oriol; Benet, Jordi; Navarro, Joaquima

2014-01-01

Comprehensive chromosome analysis techniques such as metaphase-Comparative Genomic Hybridisation (CGH) and array-CGH are available for single-cell analysis. However, while metaphase-CGH and BAC array-CGH have been widely used for Preimplantation Genetic Diagnosis, oligonucleotide array-CGH has not been used in an extensive way. A comparison between oligonucleotide array-CGH and metaphase-CGH has been performed analysing 15 single fibroblasts from aneuploid cell-lines and 18 single blastomeres from human cleavage-stage embryos. Afterwards, oligonucleotide array-CGH and BAC array-CGH were also compared analysing 16 single blastomeres from human cleavage-stage embryos. All three comprehensive analysis techniques provided broadly similar cytogenetic profiles; however, non-identical profiles appeared when extensive aneuploidies were present in a cell. Both array techniques provided an optimised analysis procedure and a higher resolution than metaphase-CGH. Moreover, oligonucleotide array-CGH was able to define extra segmental imbalances in 14.7% of the blastomeres and it better determined the specific unbalanced chromosome regions due to a higher resolution of the technique (≈ 20 kb). Applicability of oligonucleotide array-CGH for Preimplantation Genetic Diagnosis has been demonstrated in two cases of Robertsonian translocation carriers 45,XY,der(13;14)(q10;q10). Transfer of euploid embryos was performed in both cases and pregnancy was achieved by one of the couples. This is the first time that an oligonucleotide array-CGH approach has been successfully applied to Preimplantation Genetic Diagnosis for balanced chromosome rearrangement carriers.

Oligonucleotide Arrays vs. Metaphase-Comparative Genomic Hybridisation and BAC Arrays for Single-Cell Analysis: First Applications to Preimplantation Genetic Diagnosis for Robertsonian Translocation Carriers

PubMed Central

Ramos, Laia; del Rey, Javier; Daina, Gemma; García-Aragonés, Manel; Armengol, Lluís; Fernandez-Encinas, Alba; Parriego, Mònica; Boada, Montserrat; Martinez-Passarell, Olga; Martorell, Maria Rosa; Casagran, Oriol; Benet, Jordi; Navarro, Joaquima

2014-01-01

Comprehensive chromosome analysis techniques such as metaphase-Comparative Genomic Hybridisation (CGH) and array-CGH are available for single-cell analysis. However, while metaphase-CGH and BAC array-CGH have been widely used for Preimplantation Genetic Diagnosis, oligonucleotide array-CGH has not been used in an extensive way. A comparison between oligonucleotide array-CGH and metaphase-CGH has been performed analysing 15 single fibroblasts from aneuploid cell-lines and 18 single blastomeres from human cleavage-stage embryos. Afterwards, oligonucleotide array-CGH and BAC array-CGH were also compared analysing 16 single blastomeres from human cleavage-stage embryos. All three comprehensive analysis techniques provided broadly similar cytogenetic profiles; however, non-identical profiles appeared when extensive aneuploidies were present in a cell. Both array techniques provided an optimised analysis procedure and a higher resolution than metaphase-CGH. Moreover, oligonucleotide array-CGH was able to define extra segmental imbalances in 14.7% of the blastomeres and it better determined the specific unbalanced chromosome regions due to a higher resolution of the technique (≈20 kb). Applicability of oligonucleotide array-CGH for Preimplantation Genetic Diagnosis has been demonstrated in two cases of Robertsonian translocation carriers 45,XY,der(13;14)(q10;q10). Transfer of euploid embryos was performed in both cases and pregnancy was achieved by one of the couples. This is the first time that an oligonucleotide array-CGH approach has been successfully applied to Preimplantation Genetic Diagnosis for balanced chromosome rearrangement carriers. PMID:25415307

Single-stage soft tissue reconstruction and orbital fracture repair for complex facial injuries.

PubMed

Wu, Peng Sen; Matoo, Reshvin; Sun, Hong; Song, Li Yuan; Kikkawa, Don O; Lu, Wei

2017-02-01

Orbital fractures with open periorbital wounds cause significant morbidity. Timing of debridement with fracture repair and soft tissue reconstruction is controversial. This study focuses on the efficacy of early single-stage repair in combined bony and soft tissue injuries. Retrospective review. Twenty-three patients with combined open soft tissue wounds and orbital fractures were studied for single-stage orbital reconstruction and periorbital soft tissue repair. Inclusion criteria were open soft tissue wounds with clinical and radiographic evidence of orbital fractures and repair performed within 48 h after injury. Surgical complications and reconstructive outcomes were assessed over 6 months. The main outcome measures were enophthalmos, pre- and post-CT imaging of orbits, scar evaluation, presence of diplopia, and eyelid position. Enophthalmos was corrected in 16/19 cases and improved in 3/19 cases. 3D reconstruction of CT images showed markedly improved orbital alignment with objective measurements of the optic foramen to cornea distance (mm) in reconstructed orbits relative to intact orbits of 0.66, 95% confidence interval [CI] (lower 0.33, upper 0.99) mm. The mean baseline of Stony Brook Scar Evaluation Scale was 0.6, 95%CI (0.30-0.92), and for 6 months, the mean score was 3.4, 95%CI (3.05-3.73). Residual diplopia in secondary gazes was present in two patients; one patient had ectropion. Complications included one case of local wound infection. An early single-stage repair of combined soft tissue and orbital fractures yields satisfactory functional and aesthetic outcomes. Complications are low and likely related to trauma severity. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Tissue Expansion Using Hyaluronic Acid Filler for Single-Stage Ear Reconstruction: A Novel Concept for Difficult Areas.

PubMed

Inbal, Amir; Lemelman, Benjamin T; Millet, Eran; Greensmith, Andrew

2017-10-16

Auricular reconstruction is one of the most challenging procedures in plastic surgery. An adequate skin envelope is essential for cartilage framework coverage, yet few good options exist without additional surgery. We propose a novel method for minimally invasive tissue expansion, using hyaluronic acid (HA) filler to allow for single-stage ear reconstruction. To introduce the novel concept of HA filler for tissue expansion in ear reconstruction, and as an alternative to traditional expansion techniques. Macrolane is a large particle HA gel developed for large volume restoration. Expansion of the non-hair-bearing mastoid skin was performed in our clinic weekly or every other week. Final expansion was completed one week prior to reconstructive surgery. Tissue from one patient's expanded pocket was sent for histological analysis. Ten patients underwent single-stage auricular reconstruction with preoperative expansion. Injection sessions ranged from 7 to 13 (mean, 9.7). Mean injected volume per session was 2.03 mL per patient, for an average total of 19.8 mL (range, 14.5-30 mL). There were no major complications. One minor complication required removal of exposed wire from the antihelix in the office. Hematoxylin and eosin stain revealed similar histology to that seen with traditional expanders. This novel expansion technique using serial HA injections allowed for optimized skin coverage in single-stage ear reconstruction. The concept of tissue expansion using HA filler is a new frontier for research that may be applicable to other arenas of reconstruction. 4. © 2017 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com

Retrograde Ureteroscopic Management of Large Renal Calculi: A Single Institutional Experience and Concise Literature Review.

PubMed

Scotland, Kymora B; Rudnick, Benjamin; Healy, Kelly A; Hubosky, Scott G; Bagley, Demetrius H

2018-06-06

Advances in flexible ureteroscope design and accessory instrumentation have allowed for more challenging cases to be treated ureteroscopically. Here, we evaluate our experience with ureteroscopy (URS) for the management of large renal calculi (≥2 cm) and provide a concise review of recent reports. A retrospective review was undertaken of all URS cases between 2004 and 2014 performed by the endourologic team at a single academic tertiary care institution. We identified patients with at least one stone ≥2 cm managed with retrograde URS. Stone size was defined as the largest linear diameter of the index stone. Small diameter flexible ureteroscopes were used primarily with holmium laser. Patient demographics, intraoperative data, and postoperative outcomes were evaluated. We evaluated 167 consecutive patients who underwent URS for large renal stones ≥2 cm. The initial reason for choosing URS included patient preference (29.5%), failure of other therapies (8.2%), anatomic considerations/body habitus (30.3%), and comorbidities (28.8%). Mean patient age was 55.5 years (22-84). The mean stone size was 2.75 cm with mean number of procedures per patient of 1.65 (1-6). The single session stone-free rate was 57.1%, two-stage procedure stone-free rate was 90.2% and three-stage stone-free rate was 94.0%. Access sheaths were used in 47% of patients. An association was identified between stone size and patient outcomes; smaller stones correlated with decreased number of procedures. Postoperative complications were minor. Single or multi-stage retrograde ureteroscopic lithotripsy is a safe and effective mode of surgical management of large renal calculi. Total stone burden is a reliable predictor of the need for a staged procedure and of stone-free rate.

Multi-Stage ADRs for Current and Future Astronomy Missions: Performance and Requirements for Cryogen-Free Operation

NASA Technical Reports Server (NTRS)

Shirron, Peter; Kimball, Mark; Vlahacos, Kosta

2010-01-01

The cooling requirements for current (e.g. Astro-H) and future (e.g. IXO and ASP) astronomy missions pose significant challenges for the sub-Kelvin Cooler. In particular, the use of large detector arrays increases the cooling power needed, and the variety of cryocoolers that can be used for pre-cooling greatly expands the range of temperatures at which the sub-Kelvin cooler can be designed to reject heat. In most cases, there is also a need for a stable higher temperature stage for cooling amplifiers or telescope components. NASA/GSFC is currently building a 3-stage ADR for the Astro-H mission, and is developing a 5-stage ADR suitable for IXO and ASP, as well as many other missions in the early planning stages. The architecture of these ADRs allows them to be adapted rather easily for different cooling requirements and to accommodate different cryocooler capabilities (operating temperature and cooling power). This paper will discuss the performance of these ADRs, which operate in both continuous, and single-shot cooling modes, and the minimum cryocooler capabilities needed to meet the requirements of future missions.

Dysphagia in Infants with Single Ventricle Anatomy Following Stage 1 Palliation: Physiologic Correlates and Response to Treatment

PubMed Central

McGrattan, Katlyn Elizabeth; McGhee, Heather; DeToma, Allan; Hill, Elizabeth G.; Zyblewski, Sinai C.; Lefton-Greif, Maureen; Halstead, Lucinda; Bradley, Scott M.; Martin-Harris, Bonnie

2017-01-01

Background Deficits in swallowing physiology are a leading morbidity for infants with functional single ventricles and systemic outflow tract obstruction following stage 1 palliation. Despite the high prevalence of this condition, the underlying deficits that cause this post-operative impairment remain poorly understood. Objective Identify the physiologic correlates of dysphagia in infants with functional single ventricles and systemic outflow tract obstruction following stage 1 palliative surgery. Methods Postoperative fiberoptic laryngoscopies and videofluoroscopic swallow studies (VFSS) were conducted sequentially on infants with functional single ventricles following stage 1 palliative surgery. Infants were dichotomized as having normal or impaired laryngeal function based on laryngoscopy findings. VFSS were evaluated frame-by-frame using a scale that quantifies performance within 11 components of swallowing physiology. Physiologic attributes within each component were categorized as high functioning or low functioning based on their ability to support milk ingestion without bolus airway entry. Results Thirty-six infants (25 male) were included in the investigation. Twenty-four underwent the Norwood procedure and twelve underwent the Hybrid procedure. Low function physiologic patterns were observed within multiple swallowing components during the ingestion of thin barium as characterized by ≥ 4 sucks per swallow (36%), initiation of pharyngeal swallow below the level of the valleculae (83%), and incomplete late laryngeal vestibular closure (56%) at the height of the swallow. Swallowing deficits contributed to aspiration in 50% of infants. Although nectar thick liquids reduced the rate of aspiration (p=0.006), aspiration rates remained high (27%). No differences in rates of penetration or aspiration were observed between infants with normal and impaired laryngeal function. Conclusions Deficits in swallowing physiology contribute to penetration and aspiration following stage 1 palliation among infants with normal and impaired laryngeal function. Although thickened liquids may improve airway protection for select infants, they may inhibit their ability to extract the bolus and meet nutritional needs. PMID:28244680

Dysphagia in infants with single ventricle anatomy following stage 1 palliation: Physiologic correlates and response to treatment.

PubMed

McGrattan, Katlyn Elizabeth; McGhee, Heather; DeToma, Allan; Hill, Elizabeth G; Zyblewski, Sinai C; Lefton-Greif, Maureen; Halstead, Lucinda; Bradley, Scott M; Martin-Harris, Bonnie

2017-05-01

Deficits in swallowing physiology are a leading morbidity for infants with functional single ventricles and systemic outflow tract obstruction following stage 1 palliation. Despite the high prevalence of this condition, the underlying deficits that cause this post-operative impairment remain poorly understood. Identify the physiologic correlates of dysphagia in infants with functional single ventricles and systemic outflow tract obstruction following stage 1 palliative surgery. Postoperative fiberoptic laryngoscopies and videofluoroscopic swallow studies (VFSS) were conducted sequentially on infants with functional single ventricles following stage 1 palliative surgery. Infants were dichotomized as having normal or impaired laryngeal function based on laryngoscopy findings. VFSS were evaluated frame-by-frame using a scale that quantifies performance within 11 components of swallowing physiology. Physiologic attributes within each component were categorized as high functioning or low functioning based on their ability to support milk ingestion without bolus airway entry. Thirty-six infants (25 male) were included in the investigation. Twenty-four underwent the Norwood procedure and twelve underwent the Hybrid procedure. Low function physiologic patterns were observed within multiple swallowing components during the ingestion of thin barium as characterized by ≥4 sucks per swallow (36%), initiation of pharyngeal swallow below the level of the valleculae (83%), and incomplete late laryngeal vestibular closure (56%) at the height of the swallow. Swallowing deficits contributed to aspiration in 50% of infants. Although nectar thick liquids reduced the rate of aspiration (P = .006), aspiration rates remained high (27%). No differences in rates of penetration or aspiration were observed between infants with normal and impaired laryngeal function. Deficits in swallowing physiology contribute to penetration and aspiration following stage 1 palliation among infants with normal and impaired laryngeal function. Although thickened liquids may improve airway protection for select infants, they may inhibit their ability to extract the bolus and meet nutritional needs. © 2017 Wiley Periodicals, Inc.

The Impact of Dominant Ventricle Morphology on Palliation Outcomes of Single Ventricle Anomalies.

PubMed

Alsoufi, Bahaaldin; Gillespie, Scott; Kim, Dennis; Shashidharan, Subhadra; Kanter, Kirk; Maher, Kevin; Kogon, Brian

2016-08-01

Differences in right ventricle and tricuspid valve structure compared with left ventricle and mitral valve structure make them less equipped to support the systemic circulation long term, with subsequent systemic right ventricle failure. We examined the effect of dominant ventricle morphology on single ventricle palliation outcomes. We grouped 530 neonates who underwent first-stage palliation into two groups based on dominant ventricle morphology: right dominant ventricle (RV group; n = 302, 57%) and left dominant ventricle or functional single ventricle with two well-formed ventricles (LV group; n = 228, 43%). Comparisons of hospital outcomes, interstage mortality, progression to subsequent palliation stages, and late survival was performed, and factors affecting outcomes were examined. After first-stage palliation, the RV group and LV group, respectively, had comparable extracorporeal membrane oxygenation requirements (12% versus 11%, p = 0.648), unplanned reoperation (12% versus 13%, p = 0.586), and hospital death (16% versus 13%, p = 0.437). Among hospital survivors, interstage mortality (11% versus 9%, p = 0.509) and progression to Glenn operation (89% versus 84%, p = 0.182) were comparable; however, death after Glenn was higher in the RV group (10%, versus LV group 4%, p = 0.020) with a trend for lower 8-year survival (66% versus 73%, p = 0.081). On multivariable analysis, dominant RV was not associated with mortality (hazard ratio 0.75, 95% confidence interval: 0.6 to 1.0, p = 0.081), whereas factors such as genetic syndromes, weight 2.5 kg or less, underlying cardiac anomaly, and first-stage palliation type affected survival. At midterm follow-up, underlying cardiac anomaly and patient characteristics affect single ventricle palliation outcomes more than dominant ventricular morphology. As right ventricle and associated tricuspid valve failure might occur at late stages, the impact of dominant ventricular morphology on long-term outcomes requires further assessment. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Single-stage osseointegrated reconstruction and rehabilitation of lower limb amputees: the Osseointegration Group of Australia Accelerated Protocol-2 (OGAAP-2) for a prospective cohort study.

PubMed

Al Muderis, Munjed; Lu, William; Tetsworth, Kevin; Bosley, Belinda; Li, Jiao Jiao

2017-03-22

Lower limb amputations have detrimental influences on the quality of life, function and body image of the affected patients. Following amputation, prolonged rehabilitation is required for patients to be fitted with traditional socket prostheses, and many patients experience symptomatic socket-residuum interface problems which lead to reduced prosthetic use and quality of life. Osseointegration has recently emerged as a novel approach for the reconstruction of amputated limbs, which overcomes many of the socket-related problems by directly attaching the prosthesis to the skeletal residuum. To date, the vast majority of osseointegration procedures worldwide have been performed in 2 stages, which require at least 4 months and up to 18 months for the completion of reconstruction and rehabilitation from the time of the initial surgery. The current prospective cohort study evaluates the safety and efficacy of a single-stage osseointegration procedure performed under the Osseointegration Group of Australia Accelerated Protocol-2 (OGAAP-2), which dramatically reduces the time of recovery to ∼3-6 weeks. The inclusion criteria for osseointegrated reconstruction under the OGAAP-2 procedure are age over 18 years, unilateral transfemoral amputation and experiencing problems or difficulties in using socket prostheses. All patients receive osseointegrated implants which are press-fitted into the residual bone. Functional and quality-of-life outcome measures are recorded preoperatively and at defined postoperative follow-up intervals up to 2 years. Postoperative adverse events are also recorded. The preoperative and postoperative values are compared for each outcome measure, and the benefits and harms of the single-stage OGAAP-2 procedure will be compared with the results obtained using a previously employed 2-stage procedure. This study has received ethics approval from the University of Notre Dame, Sydney, Australia (014153S). The study outcomes will be disseminated by publications in peer-reviewed academic journals and presentations at relevant clinical and orthopaedic conferences. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Single-stage osseointegrated reconstruction and rehabilitation of lower limb amputees: the Osseointegration Group of Australia Accelerated Protocol-2 (OGAAP-2) for a prospective cohort study

PubMed Central

Al Muderis, Munjed; Lu, William; Tetsworth, Kevin; Bosley, Belinda; Li, Jiao Jiao

2017-01-01

Introduction Lower limb amputations have detrimental influences on the quality of life, function and body image of the affected patients. Following amputation, prolonged rehabilitation is required for patients to be fitted with traditional socket prostheses, and many patients experience symptomatic socket–residuum interface problems which lead to reduced prosthetic use and quality of life. Osseointegration has recently emerged as a novel approach for the reconstruction of amputated limbs, which overcomes many of the socket-related problems by directly attaching the prosthesis to the skeletal residuum. To date, the vast majority of osseointegration procedures worldwide have been performed in 2 stages, which require at least 4 months and up to 18 months for the completion of reconstruction and rehabilitation from the time of the initial surgery. The current prospective cohort study evaluates the safety and efficacy of a single-stage osseointegration procedure performed under the Osseointegration Group of Australia Accelerated Protocol-2 (OGAAP-2), which dramatically reduces the time of recovery to ∼3–6 weeks. Methods and analysis The inclusion criteria for osseointegrated reconstruction under the OGAAP-2 procedure are age over 18 years, unilateral transfemoral amputation and experiencing problems or difficulties in using socket prostheses. All patients receive osseointegrated implants which are press-fitted into the residual bone. Functional and quality-of-life outcome measures are recorded preoperatively and at defined postoperative follow-up intervals up to 2 years. Postoperative adverse events are also recorded. The preoperative and postoperative values are compared for each outcome measure, and the benefits and harms of the single-stage OGAAP-2 procedure will be compared with the results obtained using a previously employed 2-stage procedure. Ethics and dissemination This study has received ethics approval from the University of Notre Dame, Sydney, Australia (014153S). The study outcomes will be disseminated by publications in peer-reviewed academic journals and presentations at relevant clinical and orthopaedic conferences. PMID:28336738

Retrospective cohort study of the clinical performance of 1-stage dental implants.

PubMed

Carr, Alan B; Choi, Yong-Geun; Eckert, Steven E; Desjardins, Ronald P

2003-01-01

To evaluate long-term clinical performance of 1-stage dental implant prostheses at a single clinic, emphasizing clinical and demographic characteristics that affect implant survival. Dental records of all 308 patients (674 implants) treated with 1-stage implants at Mayo Clinic from October 1993 through May 2000 were reviewed from implant placement to last visit. Exposure and outcome variables affecting performance were collected separately to control bias in the data collection process. Additional confounding factors (age and sex) were adjusted with the stratified Cox proportional hazards model. Implant survival was determined by means of a Kaplan-Meier survival estimate. The log-rank test was used to determine the role of clinical and demographic variables in implant survival. The relative risk associated with the possible effect of clinical and demographic variables on implant survival was estimated with the Cox proportional hazards model. The implant survival rate (n = 654 implants) was 97% (mean +/- SD follow-up, 21.0 +/- 18.8 months; range, 1 to 78 months). Performance bias was limited because nearly all patients were treated by 1 prosthodontist. Two implants failed after loading (6 and 9 months). The incidence of complications was less than 4%. Among the implant failures, use of heterogeneous bone graft was associated with 4.8 times more failures than was use of autogenous bone graft (P = .04). After augmentation, delaying implant placement for 5 to 6 months resulted in 8.6 times more failures than the rate after earlier placement (P < .001). Retrospective review of the clinical performance of a 1-stage dental implant system yielded a 97% survival rate, with no failures noted after 13 months. Prosthetic complications were low, especially for fixed implant prostheses. Clinical performance of 1-stage dental implant prostheses between 1993 and 2000 demonstrated a high level of predictability.

Shape Optimization of the Assisted Bi-directional Glenn surgery for stage-1 single ventricle palliation

NASA Astrophysics Data System (ADS)

Verma, Aekaansh; Shang, Jessica; Esmaily-Moghadam, Mahdi; Wong, Kwai; Marsden, Alison

2016-11-01

Babies born with a single functional ventricle typically undergo three open-heart surgeries starting as neonates. The first of these stages (BT shunt or Norwood) has the highest mortality rates of the three, approaching 30%. Proceeding directly to a stage-2 Glenn surgery has historically demonstrated inadequate pulmonary flow (PF) & high mortality. Recently, the Assisted Bi-directional Glenn (ABG) was proposed as a promising means to achieve a stable physiology by assisting the PF via an 'ejector pump' from the systemic circulation. We present preliminary parametrization and optimization results for the ABG geometry, with the goal of increasing PF. To limit excessive pressure increases in the Superior Vena Cava (SVC), the SVC pressure is included as a constraint. We use 3-D finite element flow simulations coupled with a single ventricle lumped parameter network to evaluate PF & the pressure constraint. We employ a derivative free optimization method- the Surrogate Management Framework, in conjunction with the OpenDIEL framework to simulate multiple simultaneous evaluations. Results show that nozzle diameter is the most important design parameter affecting ABG performance. The application of these results to patient specific situations will be discussed. This work was supported by an NSF CAREER award (OCI1150184) and by the XSEDE National Computing Resource.

Space shuttle OMS helium regulator design and development

NASA Technical Reports Server (NTRS)

Wichmann, H.; Kelly, T. L.; Lynch, R.

1974-01-01

Analysis, design, fabrication and design verification testing was conducted on the technological feasiblity of the helium pressurization regulator for the space shuttle orbital maneuvering system application. A prototype regulator was fabricated which was a single-stage design featuring the most reliable and lowest cost concept. A tradeoff study on regulator concepts indicated that a single-stage regulator with a lever arm between the valve and the actuator section would offer significant weight savings. Damping concepts were tested to determine the amount of damping required to restrict actuator travel during vibration. Component design parameters such as spring rates, effective area, contamination cutting, and damping were determined by test prior to regulator final assembly. The unit was subjected to performance testing at widely ranging flow rates, temperatures, inlet pressures, and random vibration levels. A test plan for propellant compatibility and extended life tests is included.

Note: Heated flyer-plate impact system

NASA Astrophysics Data System (ADS)

Dolan, D. H.; Seagle, C. T.; Ao, T.; Hacking, R. G.

2014-07-01

A technique for launching heated flyer plates was developed on a single-stage gas gun. This type of impact creates a well-posed mechanical state and a tunable thermal state, which is useful for calibrating dynamic temperature measurements. Proof-of-principle thermoreflectance measurements were performed using this technique. Since the target remains at room temperature until the moment of impact, heated flyers avoid differential expansion and annealing issues, allowing novel impact experiments to be performed.

Note: Heated flyer-plate impact system.

PubMed

Dolan, D H; Seagle, C T; Ao, T; Hacking, R G

2014-07-01

A technique for launching heated flyer plates was developed on a single-stage gas gun. This type of impact creates a well-posed mechanical state and a tunable thermal state, which is useful for calibrating dynamic temperature measurements. Proof-of-principle thermoreflectance measurements were performed using this technique. Since the target remains at room temperature until the moment of impact, heated flyers avoid differential expansion and annealing issues, allowing novel impact experiments to be performed.

User's design handbook for a Standardized Control Module (SCM) for DC to DC Converters, volume 2

NASA Technical Reports Server (NTRS)

Lee, F. C.

1980-01-01

A unified design procedure is presented for selecting the key SCM control parameters for an arbitrarily given power stage configuration and parameter values, such that all regulator performance specifications can be met and optimized concurrently in a single design attempt. All key results and performance indices, for buck, boost, and buck/boost switching regulators which are relevant to SCM design considerations are included to facilitate frequent references.

A New {sup 14}C-AMS Facility at UFF- Niteroi, Brazil

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

Gomes, P. R. S.; Macario, K. D.; Anjos, R. M.

2010-08-04

We report a new Accelerator Mass Spectrometry facility at the Physics Institute of Fluminense Federal University in Brazil, the Nuclear Chronology Laboratory - LACRON. The sample preparation laboratory is ready to perform chemical treatment through graphitization and the acquisition of a Single Stage Accelerator Mass Spectrometry System is in progress. LACRON will be the first independent laboratory to perform the {sup 14}C-AMS technique not only in Brazil but in Latin America.

A New 14C-AMS Facility at UFF- Niteroi, Brazil

NASA Astrophysics Data System (ADS)

Gomes, P. R. S.; Macario, K. D.; Anjos, R. M.; Linares, R.; Carvalho, C.; Queiroz, E.

2010-08-01

We report a new Accelerator Mass Spectrometry facility at the Physics Institute of Fluminense Federal University in Brazil, the Nuclear Chronology Laboratory—LACRON. The sample preparation laboratory is ready to perform chemical treatment through graphitization and the acquisition of a Single Stage Accelerator Mass Spectrometry System is in progress. LACRON will be the first independent laboratory to perform the 14C-AMS technique not only in Brazil but in Latin America.

Sea wind parameters retrieval using Y-configured Doppler navigation system data. Performance and accuracy

NASA Astrophysics Data System (ADS)

Khachaturian, A. B.; Nekrasov, A. V.; Bogachev, M. I.

2018-05-01

The authors report the results of the computer simulations of the performance and accuracy of the sea wind speed and direction retrieval. The analyzed measurements over the sea surface are made by the airborne microwave Doppler navigation system (DNS) with three Y-configured beams operated as a scatterometer enhancing its functionality. Single- and double-stage wind measurement procedures are proposed and recommendations for their implementation are described.

Buckling Collapse of Midcervical Spine Secondary to Neurofibromatosis.

PubMed

Shah, Kunal C; Gadia, Akshay; Nagad, Premik; Bhojraj, Shekhar; Nene, Abhay

2018-06-01

Buckling collapse is the term typically used to describe severe kyphosis >100 degrees, characteristically seen in thoracolumbar tuberculosis. Neurofibromatosis is rarely associated with severe cervical kyphosis. Dystrophic changes in vertebra make surgical correction and fusion challenging. Single-stage cervical osteotomies (e.g., pedicle subtraction osteotomy, vertebral column resection) are commonly done in cervicothoracic junction. However, it is technically challenging and associated with high risk of vertebral artery injury, neural injury, etc. when performed in higher cervical spine. Hence in our case we did a staged procedure performing circumferential osteotomy for buckling kyphosis in the midcervical spine. Because it involved midcervical spine and there was no chin-to-chest deformity, we preferred the anterior-posterior-anterior sequence. Copyright © 2018 Elsevier Inc. All rights reserved.

Breast surgery techniques: preoperative bracketing wire localization by surgeons.

PubMed

Burkholder, Hans C; Witherspoon, Laura E; Burns, R Phillip; Horn, Jeffrey S; Biderman, Michael D

2007-06-01

With the development of expertise in image guidance for breast surgery, many surgeons now perform preoperative wire localization themselves. Use of a single wire versus multiple wires to bracket a radiographic breast abnormality has previously been described, although benefits of this technique based on clinical outcomes such as margin status, tissue volume removed, and re-excision rates have not been established. This study is a retrospective analysis of wire-localized breast biopsies performed by 14 surgeons over 29 months; stereotactic and ultrasound guidance were used. During this time, 489 wire localizations were done, of which 159 used multiple wires. Two hundred eleven of these biopsies were done for malignant disease, 86 using multiple wires. After controlling for tumor node metastases stage, single and multiple wire placements were compared using endpoints of margin status, need for re-excision, and total volume of tissue removed. Neither margin status nor re-excision was related to the number of wires placed. However, the number of wires placed was significantly related to the total volume of tissue removed. Use of more than one localizing wire was associated with greater volume of tissue removal (measured in centimeters cubed) in benign disease (46 vs 25, P < 0.001), equivalent volumes in stage 0 disease (73 vs 67), less volume in stage 1 disease (113 vs 164), and less volume in stages 2 through 4 (158 vs 207, P = 0.03). Outcomes based on surgeon case volume during the study period demonstrated that low- (1-40), medium- (41-80), and high-volume (>80) surgeons did not differ in the type or stage of breast pathology treated. Surgeons with high case volumes were more likely to place multiple localizing wires (P < 0.001) and were more likely to do a breast-conserving procedure if re-excision was performed (P < 0.018). Surgeons with low case volumes were more likely to perform a re-excision (P < 0.025). Surgeon experience has a positive impact on quality outcome measures such as performance of a definitive procedure at the time of initial surgery and use of breast-conserving procedures at the time of re-excision. Multiple wire localization can be used to significantly reduce the volume of breast tissue removed in malignant disease without sacrificing margin status or increasing the need for future re-excision.

Compact, Single-Stage MMIC InP HEMT Amplifier

NASA Technical Reports Server (NTRS)

Pukala, David; Samoska, Lorene; Fung, King Man; Gaier, Todd; Deal, W. R.; Mei, Gerry; Radisic, Vesna; Lai, Richard

2008-01-01

A monolithic micro - wave integrated-circuit (MMIC) singlestage amplifier containing an InP-based high-electron-mobility transistor (HEMT) plus coplanar-waveguide (CPW) transmission lines for impedance matching and input and output coupling, all in a highly miniaturized layout as needed for high performance at operating frequencies of hundreds of gigahertz is described.

Experimental research on a 12.1 K gas-coupled two-stage high frequency pulse tube cryocooler

NASA Astrophysics Data System (ADS)

Xiaoshuang, Zhu; Yuan, Zhou; Wenxiu, Zhu; Wei, Dai; Junjie, Wang

2017-02-01

High frequency pulse tube cryocoolers (HFPTC) have been widely used in many fields like physics experimental research and aerospace, for no moving part in cold region, low vibration and long life. A gas-coupled two-stage high frequency pulse tube cryocooler with single compressor is introduced in this paper. In the first stage of the cryocooler, double-inlet and multi-bypass has been adopted as phase shifters. To get a better performance in phase shifting the reservoir and the inertance tube of the second stage has been located on the cold head of the first stage. With SS mesh screen as the regenerator of both stage, no-load temperature of 13.5K has been achieved. To improve the heat capacity of the regenerator of the second stage magnetic material Er3Ni has been employed in the second stage as regenerator matrix. With the charge pressure of 1.8MPa, input power of 260W and operating frequency of 23.5 Hz, the no-load temperature of 12.1K has been achieved.

Temperature control in a 30 stage, 5-cm Centrifugal Contactor Pilot Plant

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

Jack D. Law; Troy G. Garn; David H. Meikrantz

2009-09-01

Temperature profile testing was performed using a 30 stage 5-cm centrifugal contactor pilot plant. These tests were performed to evaluate the ability to control process temperature by adjusting feed solution temperatures. This would eliminate the need for complex jacketed heat exchanger installation on the centrifugal contactors. Thermocouples were installed on the inlet and outlets of each stage, as well as directly in the mixing zone of several of the contactor stages. Lamp oil, a commercially available alkane mixture of C14 to C18 chains, and tap water adjusted to pH 2 with nitric acid were the solution feeds for the temperaturemore » profile testing. Temperature data profiles for an array of total throughputs and contactor rpm values for both single-phase and two-phase systems were collected with selected profiles. The total throughput ranged from 0.5-1.4 L/min with rotor speeds from 3500-4000 rpm. Inlet solution temperatures ranging from ambient up to 50 °C were tested. Results of the two-phase temperature profile testing are detailed« less

Experimental Determination of Aerodynamic Damping in a Three-Stage Transonic Axial-Flow Compressor. Degree awarded by Case Western Reserve Univ.

NASA Technical Reports Server (NTRS)

Newman, Frederick A.

1988-01-01

Rotor blade aerodynamic damping is experimentally determined in a three-stage transonic axial flow compressor having design aerodynamic performance goals of 4.5:1 pressure ratio and 65.5 lbm/sec weight flow. The combined damping associated with each mode is determined by a least squares fit of a single degree of freedom system transfer function to the nonsynchronous portion of the rotor blade strain gauge output power spectra. The combined damping consists of aerodynamic and structural and mechanical damping. The aerodynamic damping varies linearly with the inlet total pressure for a given equivalent speed, equivalent mass flow, and pressure ratio while structural and mechanical damping are assumed to be constant. The combined damping is determined at three inlet total pressure levels to obtain the aerodynamic damping. The third stage rotor blade aerodynamic damping is presented and discussed for 70, 80, 90, and 100 percent design equivalent speed. The compressor overall performance and experimental Campbell diagrams for the third stage rotor blade row are also presented.

Boiling water jet outflow from a thin nozzle: spatial modeling

NASA Astrophysics Data System (ADS)

Bolotnova, R. Kh.; Korobchinskaya, V. A.

2017-09-01

This study presents dual-temperature two-phase model for liquid-vapor mixture with account for evaporation and inter-phase heat transfer (taken in single-velocity single-pressure approximation). Simulation was performed using the shock-capturing method and moving Lagrangian grids. Analysis was performed for simulated and experimental values of nucleation frequency (for refining the initial number and radius of microbubbles) which affect the evaporation rate. Validity of 2D and 1D simulation was examined through comparison with experimental data. The peculiarities of the water-steam formation at the initial stage of outflow through a thin nozzle were studied for different initial equilibrium states of water for the conditions close to chosen experimental conditions.

Performance of Single-Stage Turbine of Mark 25 Torpedo Power Plant with Two Special Nozzles. III; Efficiency with Standard Rotor Blades

NASA Technical Reports Server (NTRS)

Schum, Harold J.; Whitney, Warren J.

1949-01-01

A Mark 25 torpedo power plant modified to operate as a single-stage turbine was investigated to determine the performance with two nozzle designs and a standard first-stage rotor having 0.40-inch blades with a 17O met-air angle. Both nozzles had smaller port cross-sectional areas than those nozzles of similar design, which were previously investigated. The performance of the two nozzles was compared on the basis of blade, rotor, and brake efficiencies as a function of blade-jet speed ratio for pressure ratios of 8, 15 (design), and 20. At pressure ratios of 15 and 20, the blade efficiency obtained with the nozzle having circular passages (K) was higher than that obtained with the nozzle having rectangular passages (J). At a pressure ratio of 8, the efficiencies obtained with the two nozzles were comparable for blade-jet speed ratios of less than 0.260. For blade-jet speed ratios exceeding this value, nozzle K yielded slightly higher efficiencies. The maximum blade efficiency of 0.569 was obtained with nozzle K at a pressure ratio of 8 and a blade-jet speed ratio of 0.295. At design speed and pressure ratio, nozzle K yielded a maximum blade efficiency of 0.534, an increase of 0.031 over that obtained with nozzle J. When the blade efficiencies of the two nozzles were compared with those of four other nozzles previously investigated, the maximum difference for the six nozzles with this rotor was 0.050. From, this comparison, no specific effect of nozzles size or shape on over-all performance was discernible.

Comparison of the 7(th) and proposed 8(th) editions of the AJCC/UICC TNM staging system for non-small cell lung cancer undergoing radical surgery.

PubMed

Jin, Ying; Chen, Ming; Yu, Xinmin

2016-09-19

The present study aims to compare the 7(th) and the proposed 8(th) edition of the AJCC/UICC TNM staging system for NSCLC in a cohort of patients from a single institution. A total of 408 patients with NSCLC who underwent radical surgery were analyzed retrospectively. Survivals were analyzed using the Kaplan -Meier method and were compared using the log-rank test. Multivariate analysis was performed by the Cox proportional hazard model. The Akaike information criterion (AIC) and C-index were applied to compare the two prognostic systems with different numbers of stages. The 7(th) AJCC T categories, the proposed 8(th) AJCC T categories, N categories, visceral pleural invasion, and vessel invasion were found to have statistically significant associations with disease-free survival (DFS) on univariate analysis. In the 7(th) edition staging system as well as in the proposed 8(th) edition, T categories, N categories, and pleural invasion were independent factors for DFS on multivariate analysis. The AIC value was smaller for the 8(th) edition compared to the 7(th) edition staging system. The C-index value was larger for the 8(th) edition compared to the 7(th) edition staging system. Based on the data from our single center, the proposed 8(th) AJCC T classification seems to be superior to the 7(th) AJCC T classification in terms of DFS for patients with NSCLC underwent radical surgery.

Design considerations for a Space Shuttle Main Engine turbine blade made of single crystal material

NASA Technical Reports Server (NTRS)

Abdul-Aziz, A.; August, R.; Nagpal, V.

1993-01-01

Nonlinear finite-element structural analyses were performed on the first stage high-pressure fuel turbopump blade of the Space Shuttle Main Engine. The analyses examined the structural response and the dynamic characteristics at typical operating conditions. Single crystal material PWA-1480 was considered for the analyses. Structural response and the blade natural frequencies with respect to the crystal orientation were investigated. The analyses were conducted based on typical test stand engine cycle. Influence of combined thermal, aerodynamic, and centrifugal loadings was considered. Results obtained showed that the single crystal secondary orientation effects on the maximum principal stresses are not highly significant.

AGT101 automotive gas turbine system development

NASA Technical Reports Server (NTRS)

Rackley, R. A.; Kidwell, J. R.

1982-01-01

The AGT101 automotive gas turbine system consisting of a 74.6 kw regenerated single-shaft gas turbine engine, is presented. The development and testing of the system is reviewed, and results for aerothermodynamic components indicate that compressor and turbine performance levels are within one percent of projected levels. Ceramic turbine rotor development is encouraging with successful cold spin testing of simulated rotors to speeds over 12,043 rad/sec. Spin test results demonstrate that ceramic materials having the required strength levels can be fabricated by net shape techniques to the thick hub cross section, which verifies the feasibility of the single-stage radial rotor in single-shaft engines.

Fluorodeoxyglucose positron emission tomography–computed tomography in evaluation of pelvic and para-aortic nodal involvement in early stage and operable cervical cancer: Comparison with surgicopathological findings

PubMed Central

Bansal, Vandana; Damania, Kaizad; Sharma, Anshu Rajnish

2011-01-01

Introduction: Nodal metastases in cervical cancer have prognostic implications. Imaging is used as an adjunct to clinical staging for evaluation of nodal metastases. Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) has an advantage of superior resolution of its CT component and detecting nodal disease based on increased glycolytic activity rather than node size. But there are limited studies describing its limitations in early stage cervical cancers. Objective: We have done meta-analysis with an objective to evaluate the efficacy of FDG PET/CT and its current clinical role in early stage and operable cervical cancer. Materials and Methods: Studies in which FDG PET/CT was performed before surgery in patients with early stage cervical cancers were included for analysis. PET findings were confirmed with histopathological diagnosis rather than clinical follow-up. FDG PET/CT showed lower sensitivity and clinically unacceptable negative predictive value in detecting nodal metastases in early stage cervical cancer and therefore, can not replace surgicopathological staging. False negative results in presence of microscopic disease and sub-centimeter diseased nodes are still the area of concern for metabolic imaging. However, these studies are single institutional and performed in a small group of patients. There is enough available evidence of clinical utility of FDG PET/CT in locally advanced cervical cancer. But these results can not be extrapolated for early stage disease. Conclusion: The current data suggest that FDG PET/CT is suboptimal in nodal staging in early stage cervical cancer. PMID:23559711

Goal-oriented cognitive rehabilitation in early-stage dementia: study protocol for a multi-centre single-blind randomised controlled trial (GREAT)

PubMed Central

2013-01-01

Background Preliminary evidence suggests that goal-oriented cognitive rehabilitation (CR) may be a clinically effective intervention for people with early-stage Alzheimer’s disease, vascular or mixed dementia and their carers. This study aims to establish whether CR is a clinically effective and cost-effective intervention for people with early-stage dementia and their carers. Methods/design In this multi-centre, single-blind randomised controlled trial, 480 people with early-stage dementia, each with a carer, will be randomised to receive either treatment as usual or cognitive rehabilitation (10 therapy sessions over 3 months, followed by 4 maintenance sessions over 6 months). We will compare the effectiveness of cognitive rehabilitation with that of treatment as usual with regard to improving self-reported and carer-rated goal performance in areas identified as causing concern by people with early-stage dementia; improving quality of life, self-efficacy, mood and cognition of people with early-stage dementia; and reducing stress levels and ameliorating quality of life for carers of participants with early-stage dementia. The incremental cost-effectiveness of goal-oriented cognitive rehabilitation compared to treatment as usual will also be examined. Discussion If the study confirms the benefits and cost-effectiveness of cognitive rehabilitation, it will be important to examine how the goal-oriented cognitive rehabilitation approach can most effectively be integrated into routine health-care provision. Our aim is to provide training and develop materials to support the implementation of this approach following trial completion. Trial registration Current Controlled Trials ISRCTN21027481 PMID:23710796

A method of estimating conceptus doses resulting from multidetector CT examinations during all stages of gestation

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

Damilakis, John; Tzedakis, Antonis; Perisinakis, Kostas

Purpose: Current methods for the estimation of conceptus dose from multidetector CT (MDCT) examinations performed on the mother provide dose data for typical protocols with a fixed scan length. However, modified low-dose imaging protocols are frequently used during pregnancy. The purpose of the current study was to develop a method for the estimation of conceptus dose from any MDCT examination of the trunk performed during all stages of gestation. Methods: The Monte Carlo N-Particle (MCNP) radiation transport code was employed in this study to model the Siemens Sensation 16 and Sensation 64 MDCT scanners. Four mathematical phantoms were used, simulatingmore » women at 0, 3, 6, and 9 months of gestation. The contribution to the conceptus dose from single simulated scans was obtained at various positions across the phantoms. To investigate the effect of maternal body size and conceptus depth on conceptus dose, phantoms of different sizes were produced by adding layers of adipose tissue around the trunk of the mathematical phantoms. To verify MCNP results, conceptus dose measurements were carried out by means of three physical anthropomorphic phantoms, simulating pregnancy at 0, 3, and 6 months of gestation and thermoluminescence dosimetry (TLD) crystals. Results: The results consist of Monte Carlo-generated normalized conceptus dose coefficients for single scans across the four mathematical phantoms. These coefficients were defined as the conceptus dose contribution from a single scan divided by the CTDI free-in-air measured with identical scanning parameters. Data have been produced to take into account the effect of maternal body size and conceptus position variations on conceptus dose. Conceptus doses measured with TLD crystals showed a difference of up to 19% compared to those estimated by mathematical simulations. Conclusions: Estimation of conceptus doses from MDCT examinations of the trunk performed on pregnant patients during all stages of gestation can be made using the method developed in the current study.« less

Progression and timing of treatment of zone I retinopathy of prematurity.

PubMed

Soh, Yuka; Fujino, Takahiro; Hatsukawa, Yoshikazu

2008-09-01

To clarify the progression of zone I retinopathy of prematurity (ROP) and elucidate the most suitable time and method of treatment. Interventional case series. Forty-six eyes of 23 zone I ROP infants were studied at a single institution. Birth weight ranged from 448 to 954 g, and gestational age ranged from 22 to 26 weeks. Fundus examination was started at 29 or 30 weeks postmenstrual age and was performed once or more per week. The first treatment was performed using laser photocoagulation or cryotherapy when zone I ROP progressed to the following criteria. Treatment criteria A included 35 eyes of 18 cases of zone I any stage ROP with plus disease (Early Treatment for Retinopathy of Prematurity [ETROP] type 1), criteria B included five eyes of three cases of zone I stage 3 ROP with or without plus disease (ETROP type 1), criteria C included six eyes of four cases of stage 1 or stage 2 ROP without plus disease; the demarcation lines belonged, in large part, within the zone I area. Hazy media such as corneal opacity, miotic pupil, tunica vasculosa lentis, and hazy vitreous persisted until approximately 32 weeks postmenstrual age. The mean period between stage 1 and stage 3 mild was one week, that between stage 1 and stage 3 moderate was 1.7 weeks, and that between stage 1 and stage 3 severe was 1.3 weeks. The period between stage 1 and the first treatment was zero to 20 days, and 60.9% of all the cases were treated within 10 days after stage 1. Six of 46 eyes had unfavorable outcomes. Surgical results of our treatment were comparable or better than those of other reports. Immediate treatment was required when zone I ROP was diagnosed behind persistent hazy media.

[The treatment of extremity bone fractures in the cases of combined injuries].

PubMed

Peshekhonov, E V; Galin, V I; Zudilin, A V; Zubok, D N

2006-12-01

The experience of treatment of 76 injured with fractures of two or more extremities in combination with affection of other anatomical areas (head, abdomen, breast, pelvis) was summarized. The extrafocal osteosynthesis was preferable because this method is characterized by low traumatism, minimal blood loss, adequate reposition, stable immobilization and possibility of early load in the apparatus of external fixation. Immersed osteosynthesis is used with great caution as it can cause the development of fat embolism. One-stage operations were performed in 26.3% victims. Their treatment periods were significantly shorter than during the multi-stage operations. One-stage operations for polytrauma have the following advantages over the multi-stage operations: single narcosis, simplified treatment in reanimation department, one post-operation period, quick rehabilitation and economic benefit. The extrafocal osteosynthesis causes less purulent complications.

The principle of a three-staged operation in the surgery of acne scars.

PubMed

Whang, K K; Lee, M

1999-01-01

Acne scars cannot be effectively corrected by a single treatment modality because of their widely varied depth and width. We assessed the effectiveness of staged combinations of several surgical modalities in the treatment of acne scars. Focal chemical peeling, carbon dioxide (CO2) laser, scar excision, punch grafting, and dermabrasion were used. Initially, focal chemical peeling was performed on all patients and then CO2 laser, scar excision, and punch grafts were used for deep scars. Finally, dermabrasion was done for the remaining scars. Seventy-five percent of patients showed excellent or good results. The degree of improvement increased as the follow-up periods and number of focal chemical peeling procedures increased and as the 3-staged operation progressed. A 3-staged operation is effective in the treatment of patients with various types of acne scars.

Performance of single-stage compressor designed on basis of constant total enthalpy with symmetrical velocity diagram at all radii and velocity ratio of 0.7 at rotor hub / Jack R. Burtt and Robert J. Jackson

NASA Technical Reports Server (NTRS)

Burtt, Jack R; Jackson, Robert J

1951-01-01

A typical inlet axial-flow compressor inlet stage, which was designed on the basis of constant total enthalpy with symmetrical velocity diagram at all radii, was investigated. At a tip speed of 1126 feet per second, a peak pressure ratio of 1.28 was obtained at an efficiency of 0.76. At a tip speed, the highest practical flow was 28 pounds per second per square foot frontal area with an efficiency of 0.78. Data for a rotor relative inlet Mach number range of from 0.5 to 0.875 indicates that the critical value for any stage radial element is approximately 0.80 for the stage investigated.

ARES I Upper Stage Subsystems Design and Development

NASA Technical Reports Server (NTRS)

Frate, David T.; Senick, Paul F.; Tolbert, Carol M.

2011-01-01

From 2005 through early 2011, NASA conducted concept definition, design, and development of the Ares I launch vehicle. The Ares I was conceived to serve as a crew launch vehicle for beyond-low-Earth-orbit human space exploration missions as part of the Constellation Program Architecture. The vehicle was configured with a single shuttle-derived solid rocket booster first stage and a new liquid oxygen/liquid hydrogen upper stage, propelled by a single, newly developed J-2X engine. The Orion Crew Exploration Vehicle was to be mated to the forward end of the Ares I upper stage through an interface with fairings and a payload adapter. The vehicle design passed a Preliminary Design Review in August 2008, and was nearing the Critical Design Review when efforts were concluded as a result of the Constellation Program s cancellation. At NASA Glenn Research Center, four subsystems were developed for the Ares I upper stage. These were thrust vector control (TVC) for the J-2X, electrical power system (EPS), purge and hazardous gas (P&HG), and development flight instrumentation (DFI). The teams working each of these subsystems achieved 80 percent or greater design completion and extensive development testing. These efforts were extremely successful representing state-of-the-art technology and hardware advances necessary to achieve Ares I reliability, safety, availability, and performance requirements. This paper documents the designs, development test activity, and results.

CFD-Modeling of the Multistage Gasifier Capacity of 30 KW

NASA Astrophysics Data System (ADS)

Levin, A. A.; Kozlov, A. N.; Svishchev, D. A.; Donskoy, I. G.

2017-11-01

Single-stage fuel gasification processes have been developed and widely studied in Russia and abroad throughout the 20th century. They are fundamental to the creation and design of modern gas generator equipment. Many studies have shown that single-stage gasification process, have already reached the limit of perfection, which was a significant improvement in their performance becomes impossible and unprofitable. The most fully meet modern technical requirements of multistage gasification technology. In the first step of the process, is organized allothermic biomass pyrolysis using heat of exhaust gas and generating power plant. At this stage, the yield of volatile products (gas and tar) of fuel. In the second step, the layer of fuel is, the tar is decomposed by the action of hot air and steam, steam-gas mixture is formed further reacts with the charcoal in the third process stage. The paper presents a model developed by the authors of the multi-stage gasifier for wood chips. The model is made with the use of CFD-modeling software package (COMSOL Multiphisics). To describe the kinetics of wood pyrolysis and gasification of charcoal studies were carried out using a set of simultaneous thermal analysis. For this complex developed original methods of interpretation of measurements, including methods of technical analysis of fuels and determine the parameters of the detailed kinetics and mechanism of pyrolysis.

Large cooling differentials and high heat flux capability with p-type Bi2Te3/Sb2Te3 and n-type Bi2Te3/Bi2SexTe3-x Superlattice Thermoelectric Devices

NASA Astrophysics Data System (ADS)

Bulman, Gary; Siivola, Ed; Wiitala, Ryan; Grant, Brian; Pierce, Jonathan; Venkatasubramanian, Rama

2007-03-01

Thin film superlattice (SL) based thermoelectric (TE) devices offer the potential for improved efficiency and high heat flux cooling over conventional bulk materials. Recently, we have demonstrated external cooling of 55K and heat pumping capacity of 128 W/cm^2. These high heat fluxes in thin film devices, while attractive for cooling hot-spots in electronics, also make the device performance sensitive to various thermal resistances in the device structure. We will discuss advances in the cooling performance of Bi2Te3-based SL TE devices and describe a method to extract device material parameters, including thermal resistance, from measurements of their δT-I-V characteristics. These parameters will be compared to values obtained through Hall and Seebeck coefficient measurement on epitaxial materials. Results will be presented for both single couple and multi-couple modules, as well as multi-stage cascaded devices made with these materials. Single stage cooling couples with δTmax of 57.8K (Tc˜242K) and multi-stage modules with δTmax˜92.2K (Tc˜209K) have been measured. G.E. Bulman, E. Siivola, B. Shen and R. Venkatasubramanian, Appl. Phys. Lett. 89, 122117 (2006).

Rocket nozzle expansion ratio analysis for dual-fuel earth-to-orbit vehicles

NASA Technical Reports Server (NTRS)

Martin, James A.

1989-01-01

Results are reported from a recent study of the effects of Space Shuttle Main Engine expansion ratio modifications, in the cases of both single-stage and two-stage systems. Two-position nozzles were employed; after varying the lower expansion ratio while the higher was held constant at 120, the lower expansion ratio was held constant at 40 or 60 while the higher expansion ratio was varied. The expansion ratios for minimum vehicle dry mass are different for single-stage and two-stage systems. For two-stage systems, a single expansion ratio of 77.5 provides a lower dry mass than any two-position nozzle.

Single-Phase Single-Stage Grid Tied Solar PV System with Active Power Filtering Using Power Balance Theory

NASA Astrophysics Data System (ADS)

Singh, Yashi; Hussain, Ikhlaq; Singh, Bhim; Mishra, Sukumar

2018-06-01

In this paper, power quality features such as harmonics mitigation, power factor correction with active power filtering are addressed in a single-stage, single-phase solar photovoltaic (PV) grid tied system. The Power Balance Theory (PBT) with perturb and observe based maximum power point tracking algorithm is proposed for the mitigation of power quality problems in a solar PV grid tied system. The solar PV array is interfaced to a single phase AC grid through a Voltage Source Converter (VSC), which provides active power flow from a solar PV array to the grid as well as to the load and it performs harmonics mitigation using PBT based control. The solar PV array power varies with sunlight and due to this, the solar PV grid tied VSC works only 8-10 h per day. At night, when PV power is zero, the VSC works as an active power filter for power quality improvement, and the load active power is delivered by the grid to the load connected at the point of common coupling. This increases the effective utilization of a VSC. The system is modelled and simulated using MATLAB and simulated responses of the system at nonlinear loads and varying environmental conditions are also validated experimentally on a prototype developed in the laboratory.

Single-Phase Single-Stage Grid Tied Solar PV System with Active Power Filtering Using Power Balance Theory

NASA Astrophysics Data System (ADS)

Singh, Yashi; Hussain, Ikhlaq; Singh, Bhim; Mishra, Sukumar

2018-03-01

In this paper, power quality features such as harmonics mitigation, power factor correction with active power filtering are addressed in a single-stage, single-phase solar photovoltaic (PV) grid tied system. The Power Balance Theory (PBT) with perturb and observe based maximum power point tracking algorithm is proposed for the mitigation of power quality problems in a solar PV grid tied system. The solar PV array is interfaced to a single phase AC grid through a Voltage Source Converter (VSC), which provides active power flow from a solar PV array to the grid as well as to the load and it performs harmonics mitigation using PBT based control. The solar PV array power varies with sunlight and due to this, the solar PV grid tied VSC works only 8-10 h per day. At night, when PV power is zero, the VSC works as an active power filter for power quality improvement, and the load active power is delivered by the grid to the load connected at the point of common coupling. This increases the effective utilization of a VSC. The system is modelled and simulated using MATLAB and simulated responses of the system at nonlinear loads and varying environmental conditions are also validated experimentally on a prototype developed in the laboratory.

Comparison of digital signal-signal beat interference compensation techniques in direct-detection subcarrier modulation systems.

PubMed

Li, Zhe; Erkilinc, M Sezer; Galdino, Lidia; Shi, Kai; Thomsen, Benn C; Bayvel, Polina; Killey, Robert I

2016-12-12

Single-polarization direct-detection transceivers may offer advantages compared to digital coherent technology for some metro, back-haul, access and inter-data center applications since they offer low-cost and complexity solutions. However, a direct-detection receiver introduces nonlinearity upon photo detection, since it is a square-law device, which results in signal distortion due to signal-signal beat interference (SSBI). Consequently, it is desirable to develop effective and low-cost SSBI compensation techniques to improve the performance of such transceivers. In this paper, we compare the performance of a number of recently proposed digital signal processing-based SSBI compensation schemes, including the use of single- and two-stage linearization filters, an iterative linearization filter and a SSBI estimation and cancellation technique. Their performance is assessed experimentally using a 7 × 25 Gb/s wavelength division multiplexed (WDM) single-sideband 16-QAM Nyquist-subcarrier modulation system operating at a net information spectral density of 2.3 (b/s)/Hz.

An Efficient Framework Model for Optimizing Routing Performance in VANETs.

PubMed

Al-Kharasani, Nori M; Zulkarnain, Zuriati Ahmad; Subramaniam, Shamala; Hanapi, Zurina Mohd

2018-02-15

Routing in Vehicular Ad hoc Networks (VANET) is a bit complicated because of the nature of the high dynamic mobility. The efficiency of routing protocol is influenced by a number of factors such as network density, bandwidth constraints, traffic load, and mobility patterns resulting in frequency changes in network topology. Therefore, Quality of Service (QoS) is strongly needed to enhance the capability of the routing protocol and improve the overall network performance. In this paper, we introduce a statistical framework model to address the problem of optimizing routing configuration parameters in Vehicle-to-Vehicle (V2V) communication. Our framework solution is based on the utilization of the network resources to further reflect the current state of the network and to balance the trade-off between frequent changes in network topology and the QoS requirements. It consists of three stages: simulation network stage used to execute different urban scenarios, the function stage used as a competitive approach to aggregate the weighted cost of the factors in a single value, and optimization stage used to evaluate the communication cost and to obtain the optimal configuration based on the competitive cost. The simulation results show significant performance improvement in terms of the Packet Delivery Ratio (PDR), Normalized Routing Load (NRL), Packet loss (PL), and End-to-End Delay (E2ED).

Legal abortion services in Brazil--a national study.

PubMed

Madeiro, Alberto Pereira; Diniz, Debora

2016-02-01

This article presents the results of a mixed methods study of 68 legal abortion services in Brazil. The services were analyzed in two stages. The first stage was a census, in which all the institutions were sent an electronic questionnaire about the organization of the legal abortion services. The second stage was conducted in a sample of 5 reference services, one for each region of the country. In this stage, a form was used to collect data about the women and the abortions in the medical records, and 82 interviews with health professionals were conducted. Thirty-seven of the services informed they performed legal abortions, and the services were inactive in 7 states. Police reports, forensic reports, and court orders were required by 14%, 8% and 8% of the services, respectively. Women who underwent abortions were predominantly aged 15-29, single and Catholic. Most abortions were performed until 14 weeks in the case of rape-related pregnancy, by means of manual vacuum aspiration. According to the health professionals, the main difficulties faced in the services are the low availability of physicians to perform abortions and the insufficient training of the staff. The data reveal a discrepancy between the legal provision and the reality of the services. The implementation of more services and the strengthening of the existing services available are necessary.

Correlation Between the Microstructural Defects and Residual Stress in a Single Crystal Nickel-Based Superalloy During Different Creep Stages

NASA Astrophysics Data System (ADS)

Mo, Fangjie; Wu, Erdong; Zhang, Changsheng; Wang, Hong; Zhong, Zhengye; Zhang, Jian; Chen, Bo; Hofmann, Michael; Gan, Weimin; Sun, Guangai

2018-03-01

The present work attempts to reveal the correlation between the microstructural defects and residual stress in the single crystal nickel-based superalloy, both of which play the significant role on properties and performance. Neutron diffraction was employed to investigate the microstructural defects and residual stresses in a single crystal (SC) nickel-based superalloy, which was subjected to creeping under 220 MPa and 1000 °C for different times. The measured superlattice and fundamental lattice reflections confirm that the mismatch and tetragonal distortions with c/a > 1 exist in the SC superalloy. At the initially unstrained state, there exists the angular distortion between γ and γ' phases with small triaxial compressive stresses, ensuring the structural stability of the superalloy. After creeping, the tetragonal distortion for the γ phase is larger than that for the γ' phase. With increasing the creeping time, the mismatch between γ and γ' phases increases to the maximum, then decreases gradually and finally remains unchanged. The macroscopic residual stress shows a similar behavior with the mismatch, indicating the correlation between them. Based on the model of shear and dislocations, the evolution of microstructural defects and residual stress are reasonably explained. The effect of shear is dominant at the primary creep stage, which greatly enlarges the mismatch and the residual stress. The dislocations weaken the effect of shear for the further creep stage, resulting in the decrease of the mismatch and relaxation of the residual stress. Those findings add some helpful understanding into the microstructure-performance relationship in the SC nickel-based superalloy, which might provide the insight to materials design and applications.

SPECHT - single-stage phosphopeptide enrichment and stable-isotope chemical tagging: quantitative phosphoproteomics of insulin action in muscle.

PubMed

Kettenbach, Arminja N; Sano, Hiroyuki; Keller, Susanna R; Lienhard, Gustav E; Gerber, Scott A

2015-01-30

The study of cellular signaling remains a significant challenge for translational and clinical research. In particular, robust and accurate methods for quantitative phosphoproteomics in tissues and tumors represent significant hurdles for such efforts. In the present work, we design, implement and validate a method for single-stage phosphopeptide enrichment and stable isotope chemical tagging, or SPECHT, that enables the use of iTRAQ, TMT and/or reductive dimethyl-labeling strategies to be applied to phosphoproteomics experiments performed on primary tissue. We develop and validate our approach using reductive dimethyl-labeling and HeLa cells in culture, and find these results indistinguishable from data generated from more traditional SILAC-labeled HeLa cells mixed at the cell level. We apply the SPECHT approach to the quantitative analysis of insulin signaling in a murine myotube cell line and muscle tissue, identify known as well as new phosphorylation events, and validate these phosphorylation sites using phospho-specific antibodies. Taken together, our work validates chemical tagging post-single-stage phosphoenrichment as a general strategy for studying cellular signaling in primary tissues. Through the use of a quantitatively reproducible, proteome-wide phosphopeptide enrichment strategy, we demonstrated the feasibility of post-phosphopeptide purification chemical labeling and tagging as an enabling approach for quantitative phosphoproteomics of primary tissues. Using reductive dimethyl labeling as a generalized chemical tagging strategy, we compared the performance of post-phosphopeptide purification chemical tagging to the well established community standard, SILAC, in insulin-stimulated tissue culture cells. We then extended our method to the analysis of low-dose insulin signaling in murine muscle tissue, and report on the analytical and biological significance of our results. Copyright © 2014 Elsevier B.V. All rights reserved.

High average power diode pumped solid state laser

NASA Astrophysics Data System (ADS)

Gao, Yue; Wang, Yanjie; Chan, Amy; Dawson, Murray; Greene, Ben

2017-03-01

A new generation of high average power pulsed multi-joule solid state laser system has been developed at EOS Space Systems for various space related tracking applications. It is a completely diode pumped, fully automated multi-stage system consisting of a pulsed single longitudinal mode oscillator, three stages of pre-amplifiers, two stages of power amplifiers, completely sealed phase conjugate mirror or stimulated Brillouin scattering (SBS) cell and imaging relay optics with spatial filters in vacuum cells. It is capable of generating pulse energy up to 4.7 J, a beam quality M 2 ~ 3, pulse width between 10-20 ns, and a pulse repetition rate between 100-200 Hz. The system has been in service for more than two years with excellent performance and reliability.

Thermal performance testing of two Thales 9310 pulse-tube cryocoolers for PHyTIR

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

Paine, Christopher G.

2014-01-29

PHyTIR is a NASA-funded technology demonstration for a near-term earth-observing instrument in the thermal infrared spectrum, intended for use in the HyspIRI mission. PHyTIR will use two Thales 9310 single-stage pulse tube cryocoolers, one to directly cool the FPA, the other to simulate a passive radiator. We report performance measurements for the two Thales 9310 cryocoolers intended for inclusion in the PHyTIR demonstrator.

Hyperventilation complaints in music performance anxiety among classical music students.

PubMed

Studer, Regina; Danuser, Brigitta; Hildebrandt, Horst; Arial, Marc; Gomez, Patrick

2011-06-01

Despite the importance of respiration and hyperventilation in anxiety disorders, research on breathing disturbances associated with hyperventilation is rare in the field of music performance anxiety (MPA, also known as stage fright). The only comparable study in this area reported a positive correlation between negative feelings of MPA and hyperventilation complaints during performance. The goals of this study were (a) to extend these previous findings to the period before performance, (b) to test whether a positive correlation also exists between hyperventilation complaints and the experience of stage fright as a problem, (c) to investigate instrument-specific symptom reporting, and (d) to confirm gender differences in negative feelings of MPA and hyperventilation complaints reported in other studies. We assessed 169 university students of classical music with a questionnaire comprising: the State-Trait Anxiety Inventory for negative feelings of MPA, the Nijmegen Questionnaire for hyperventilation complaints, and a single item for the experience of stage fright as a problem. We found a significant positive correlation between hyperventilation complaints and negative feelings of MPA before performance and a significant positive correlation between hyperventilation complaints and the experience of stage fright as a problem. Wind musicians/singers reported a significantly higher frequency of respiratory symptoms than other musicians. Furthermore, women scored significantly higher on hyperventilation complaints and negative feelings of MPA. These results further the findings of previous reports by suggesting that breathing disturbances associated with hyperventilation may play a role in MPA prior to going on stage. Experimental studies are needed to confirm whether hyperventilation complaints associated with negative feelings of MPA manifest themselves at the physiological level. Copyright © 2010 Elsevier Inc. All rights reserved.

A comprehensive method for preliminary design optimization of axial gas turbine stages

NASA Technical Reports Server (NTRS)

Jenkins, R. M.

1982-01-01

A method is presented that performs a rapid, reasonably accurate preliminary pitchline optimization of axial gas turbine annular flowpath geometry, as well as an initial estimate of blade profile shapes, given only a minimum of thermodynamic cycle requirements. No geometric parameters need be specified. The following preliminary design data are determined: (1) the optimum flowpath geometry, within mechanical stress limits; (2) initial estimates of cascade blade shapes; (3) predictions of expected turbine performance. The method uses an inverse calculation technique whereby blade profiles are generated by designing channels to yield a specified velocity distribution on the two walls. Velocity distributions are then used to calculate the cascade loss parameters. Calculated blade shapes are used primarily to determine whether the assumed velocity loadings are physically realistic. Model verification is accomplished by comparison of predicted turbine geometry and performance with four existing single stage turbines.

Two-stage earth-to-orbit vehicles with dual-fuel propulsion in the Orbiter

NASA Technical Reports Server (NTRS)

Martin, J. A.

1982-01-01

Earth-to-orbit vehicle studies of future replacements for the Space Shuttle are needed to guide technology development. Previous studies that have examined single-stage vehicles have shown advantages for dual-fuel propulsion. Previous two-stage system studies have assumed all-hydrogen fuel for the Orbiters. The present study examined dual-fuel Orbiters and found that the system dry mass could be reduced with this concept. The possibility of staging the booster at a staging velocity low enough to allow coast-back to the launch site is shown to be beneficial, particularly in combination with a dual-fuel Orbiter. An engine evaluation indicated the same ranking of engines as did a previous single-stage study. Propane and RP-1 fuels result in lower vehicle dry mass than methane, and staged-combustion engines are preferred over gas-generator engines. The sensitivity to the engine selection is less for two-stage systems than for single-stage systems.

[Comparative study on clinical and pathological changes of liver fibrosis with diffusion-weighted imaging].

PubMed

Zhou, Mei-Ling; Yan, Fu-Hua; Xu, Peng-Ju; Chen, Cai-Zhong; Shen, Ji-Zhang; Li, Ren-Chen; Ji, Yuan; Shi, Jian-Ying

2009-07-07

To evaluate the clinical practical value of apparent diffusion coefficient (ADC) measurements based on diffusion-weighted MR imaging (DWI) for quantification of liver fibrosis and inflammation for hepatitis viral infection. Diffusion-weighted MRI with parallel imaging was prospectively performed on 85 patients with chronic hepatitis and on 22 healthy volunteers within a single breath-hold using a single-shot spin-echo echo-planar sequence at b values of 100, 300, 500, 800 and 1000 s/mm2 respectively. ADC values of liver were measured with five different b values. The inflammation grades and fibrosis stages were evaluated histologically by biopsy. One-way analysis of variance and Spearman' s rank correlation test were used for statistical analysis. Receiver operating characteristics analysis was used to assess the performance of ADC in predicting the presence of stage > or = 2 and stage > or = 3 hepatic fibrosis, and grade > or = 1 hepatic inflammation. There was moderate negative correlation between hepatic ADC values and fibrosis stage. And the best correlation was obtained for a b value of 800 s/mm2 (r = -0.697, P = 0. 000). At all b values there was a significant decrease in hepatic ADC in patients with stage < or = 1 versus stage > or = 2 fibrosis and stage < or = 2 versus stage > or = 3 fibrosis (P < 0.05). Hepatic ADC was a significant predictor of stage > or = 2 and > or = 3 fibrosis. The areas under the curve were 0.909 vs 0.917, sensitivity 76.6% vs 80.0% and specificity 88.3% vs 91.5% (ADC with a b value of 800 s/mm2, 1.26 x 10(-3) mm2/s or less and 1.19 x 10(-3) mm2/s or less). There was weak to moderate negative correlation between ADCs and inflammation grade. Hepatic ADC was a significant predictor of grade > 1 inflammation with an area under the curve of 0.781, sensitivity of 60.0% and specificity of 86.4% (ADC with a b value of 500 s/mm2, 1.54 x 10(-3) mm2/s or less). The DWI measurement of hepatic ADC can be used to quantify liver fibrosis and inflammation. It will be a new approach for early diagnosis and therapeutic follow-up of hepatic fibrosis.

FATE OF TRACE METALS IN A ROTARY KILN INCINERATOR WITH A SINGLE-STAGE IONIZING WET SCRUBBER. VOLUME 1. TECHNICAL RESULTS.

EPA Science Inventory

A series of pilot-scale incineration tests was performed at EPA's Incineration Research Facility (IRF) in Jefferson, Arkansas, to evaluate the fate of trace metals fed to a rotary kiln incinerator equipped with an ionizing wet scrubber (IWS) for particulate and acid gas control. ...

Rocket-powered single-stage-to-orbit vehicles for safe economical access to low earth orbit

NASA Astrophysics Data System (ADS)

Andrews, D. G.; Davis, E. E.; Bangsund, E. L.

1991-10-01

Rocket-powered SSTO vehicles were investigated during the SSTO technology demonstration contracts. Vehicle configurations were defined to include various technology concepts such as advanced rocket or air breathing engines, takeoff assist options, and advanced high temperature structural materials. Results of these investigations are summarized and performance and turnaround data are presented.

Note: a transimpedance amplifier for remotely located quartz tuning forks.

PubMed

Kleinbaum, Ethan; Csáthy, Gábor A

2012-12-01

The cable capacitance in cryogenic and high vacuum applications of quartz tuning forks imposes severe constraints on the bandwidth and noise performance of the measurement. We present a single stage low noise transimpedance amplifier with a bandwidth exceeding 1 MHz and provide an in-depth analysis of the dependence of the amplifier parameters on the cable capacitance.

THE FATE OF TRACE METALS IN A ROTARY KILN INCINERATOR WITH A SINGLE-STAGE IONIZING WET SCRUBBER - VOLUME II: APPENDICES

EPA Science Inventory

A series of pilot-scale incineration tests was performed at EPA's Incineration Research Facility (IRF) in Jefferson, Arkansas, to evaluate the fate of trace metals fed to a rotary kiln incinerator equipped with an ionizing wet scrubber (IWS) for particulate and acid gas control. ...

Identification and functional analysis of long non-coding RNAs in human and mouse early embryos based on single-cell transcriptome data

PubMed Central

Qiu, Jia-jun; Ren, Zhao-rui; Yan, Jing-bin

2016-01-01

Epigenetics regulations have an important role in fertilization and proper embryonic development, and several human diseases are associated with epigenetic modification disorders, such as Rett syndrome, Beckwith-Wiedemann syndrome and Angelman syndrome. However, the dynamics and functions of long non-coding RNAs (lncRNAs), one type of epigenetic regulators, in human pre-implantation development have not yet been demonstrated. In this study, a comprehensive analysis of human and mouse early-stage embryonic lncRNAs was performed based on public single-cell RNA sequencing data. Expression profile analysis revealed that lncRNAs are expressed in a developmental stage–specific manner during human early-stage embryonic development, whereas a more temporal-specific expression pattern was identified in mouse embryos. Weighted gene co-expression network analysis suggested that lncRNAs involved in human early-stage embryonic development are associated with several important functions and processes, such as oocyte maturation, zygotic genome activation and mitochondrial functions. We also found that the network of lncRNAs involved in zygotic genome activation was highly preservative between human and mouse embryos, whereas in other stages no strong correlation between human and mouse embryo was observed. This study provides insight into the molecular mechanism underlying lncRNA involvement in human pre-implantation embryonic development. PMID:27542205

Optimized multiple linear mappings for single image super-resolution

NASA Astrophysics Data System (ADS)

Zhang, Kaibing; Li, Jie; Xiong, Zenggang; Liu, Xiuping; Gao, Xinbo

2017-12-01

Learning piecewise linear regression has been recognized as an effective way for example learning-based single image super-resolution (SR) in literature. In this paper, we employ an expectation-maximization (EM) algorithm to further improve the SR performance of our previous multiple linear mappings (MLM) based SR method. In the training stage, the proposed method starts with a set of linear regressors obtained by the MLM-based method, and then jointly optimizes the clustering results and the low- and high-resolution subdictionary pairs for regression functions by using the metric of the reconstruction errors. In the test stage, we select the optimal regressor for SR reconstruction by accumulating the reconstruction errors of m-nearest neighbors in the training set. Thorough experimental results carried on six publicly available datasets demonstrate that the proposed SR method can yield high-quality images with finer details and sharper edges in terms of both quantitative and perceptual image quality assessments.

Temperature Profile Measurements in a Newly Constructed 30-Stage 5 cm Centrifugal Contactor pilot Plant

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

Troy G. Garn; Dave H. Meikrantz; Mitchell R. Greenhalgh

2008-09-01

An annular centrifugal contactor pilot plant incorporating 30 stages of commercial 5 cm CINC V-02 units has been built and operated at INL during the past year. The pilot plant includes an automated process control and data acquisitioning system. The primary purpose of the pilot plant is to evaluate the performance of a large number of inter-connected centrifugal contactors and obtain temperature profile measurements within a 30-stage cascade. Additional solvent extraction flowsheet testing using stable surrogates is also being considered. Preliminary hydraulic testing was conducted with all 30 contactors interconnected for continuous counter-current flow. Hydraulic performance and system operational testsmore » were conducted successfully but with higher single-stage rotor speeds found necessary to maintain steady interstage flow at flowrates of 1 L/min and higher. Initial temperature profile measurements were also completed in this configuration studying the performance during single aqueous and two-phase counter-current flow at ambient and elevated inlet solution temperatures. Temperature profile testing of two discreet sections of the cascade required additional feed and discharge connections. Lamp oil, a commercially available alkane mixture of C14 to C18 chains, and tap water adjusted to pH 2 were the solution feeds for all the testing described in this report. Numerous temperature profiles were completed using a newly constructed 30-stage centrifugal contactor pilot plant. The automated process control and data acquisition system worked very well throughout testing. Temperature data profiles for an array of total flowrates (FT) and contactor rpm values for both single-phase and two-phase systems have been collected with selected profiles and comparisons reported. Total flowrates (FT) ranged from 0.5-1.4 L/min with rotor speeds from 3500-4000 rpm. Solution inlet temperatures ranging from ambient up to 50° C were tested. Ambient temperature testing shows that a small amount of heat is added to the processed solution by the mechanical energy of the contactors. The temperature profiles match the ambient temperature of the laboratory but are nearly 10° C higher toward the middle of the cascade. Heated input solution testing provides temperature profiles with smaller temperature gradients and are more influenced by the temperature of the inlet solutions than the ambient laboratory temperature. The temperature effects of solution mixing, even at 4000 rpm, were insignificant in any of the studies conducted on lamp oil and water.« less

Single-Stage Primary Cleft Lip and Palate Repair: A Review of the Literature.

PubMed

Kantar, Rami S; Rifkin, William J; Cammarata, Michael J; Maliha, Samantha G; Diaz-Siso, J Rodrigo; Farber, Scott J; Flores, Roberto L

2018-06-26

Single-stage cleft lip and palate repair is a debated surgical approach. While some studies have described favorable outcomes, concerns include the effect on craniomaxillofacial growth and increased risk of complications. To this date, there has not been a comprehensive appraisal of available data following combined cleft lip and palate repair. An extensive literature review was performed to identify all relevant articles. The level of evidence of these articles was graded according to the Oxford Centre for Evidence-Based Medicine Levels of Evidence Scale. A total of 22 relevant articles were identified, all of which were retrospective in nature. Patient age at the time of surgery ranged from 1 month to 10 years, the longest duration of follow-up was 18 years, and the largest study included 106 patients. Review of the literature shows that overall surgical outcomes following combined cleft lip and palate repair are encouraging. An increased rate of postoperative fistulas with associated speech abnormalities in some studies is noteworthy. Importantly, there is no evidence to suggest an impact on craniomaxillofacial growth, and psychosocial outcomes and parental satisfaction seem to be improved with single-stage surgery as compared with the staged approach. Our review shows overall favorable outcomes associated with combined cleft lip and palate repair. The limited follow-up time or nature of evaluated outcomes in some studies may underrepresent the true rate of adverse events, and highlights the need for additional long-term studies with standardized follow-up. To our knowledge, our review is the first to evaluate existing data regarding outcomes following combined cleft lip and palate repair.

Multi-stage FE simulation of hot ring rolling

NASA Astrophysics Data System (ADS)

Wang, C.; Geijselaers, H. J. M.; van den Boogaard, A. H.

2013-05-01

As a unique and important member of the metal forming family, ring rolling provides a cost effective process route to manufacture seamless rings. Applications of ring rolling cover a wide range of products in aerospace, automotive and civil engineering industries [1]. Above the recrystallization temperature of the material, hot ring rolling begins with the upsetting of the billet cut from raw stock. Next a punch pierces the hot upset billet to form a hole through the billet. This billet, referred to as preform, is then rolled by the ring rolling mill. For an accurate simulation of hot ring rolling, it is crucial to include the deformations, stresses and strains from the upsetting and piercing process as initial conditions for the rolling stage. In this work, multi-stage FE simulations of hot ring rolling process were performed by mapping the local deformation state of the workpiece from one step to the next one. The simulations of upsetting and piercing stages were carried out by 2D axisymmetric models using adaptive remeshing and element erosion. The workpiece for the ring rolling stage was subsequently obtained after performing a 2D to 3D mapping. The commercial FE package LS-DYNA was used for the study and user defined subroutines were implemented to complete the control algorithm. The simulation results were analyzed and also compared with those from the single-stage FE model of hot ring rolling.

Signal detection evidence for limited capacity in visual search

PubMed Central

Fencsik, David E.; Flusberg, Stephen J.; Horowitz, Todd S.; Wolfe, Jeremy M.

2014-01-01

The nature of capacity limits (if any) in visual search has been a topic of controversy for decades. In 30 years of work, researchers have attempted to distinguish between two broad classes of visual search models. Attention-limited models have proposed two stages of perceptual processing: an unlimited-capacity preattentive stage, and a limited-capacity selective attention stage. Conversely, noise-limited models have proposed a single, unlimited-capacity perceptual processing stage, with decision processes influenced only by stochastic noise. Here, we use signal detection methods to test a strong prediction of attention-limited models. In standard attention-limited models, performance of some searches (feature searches) should only be limited by a preattentive stage. Other search tasks (e.g., spatial configuration search for a “2” among “5”s) should be additionally limited by an attentional bottleneck. We equated average accuracies for a feature and a spatial configuration search over set sizes of 1–8 for briefly presented stimuli. The strong prediction of attention-limited models is that, given overall equivalence in performance, accuracy should be better on the spatial configuration search than on the feature search for set size 1, and worse for set size 8. We confirm this crossover interaction and show that it is problematic for at least one class of one-stage decision models. PMID:21901574

Single-Anesthetic Versus Staged Bilateral Total Hip Arthroplasty: A Matched Cohort Study.

PubMed

Houdek, Matthew T; Wyles, Cody C; Watts, Chad D; Wagner, Eric R; Sierra, Rafael J; Trousdale, Robert T; Taunton, Michael J

2017-01-04

There is debate regarding the role of single-anesthetic versus staged bilateral total hip arthroplasty (THA) for patients with end-stage bilateral osteoarthritis. Studies have shown that single-anesthetic bilateral THA is associated with systemic complications, but there are limited data comparing patient outcomes in a matched setting of bilateral THA. We identified 94 patients (188 hips) who underwent single-anesthetic bilateral THA. Fifty-seven percent of the patients were male. Patients had a mean age of 52.2 years and body mass index of 27.1 kg/m. They were matched 1:1 on the basis of sex, age (±1 year), and year of surgery (±3 years) to a cohort of patients undergoing staged bilateral THA. In the staged group, there was <1 year between procedures (range, 5 days to 10 months). Mean follow-up was 4 years for each group. Patients in the single-anesthetic group experienced shorter total operating room time and length of stay. There was no difference (hazard ratio [HR] = 0.73, p = 0.50) in the overall revision-free survival in patients undergoing single-anesthetic or staged bilateral THA. The risks of reoperation (HR = 0.69, p = 0.40), complications (HR = 0.83, p = 0.48), and mortality (HR = 0.47, p = 0.10) were similar. Single-anesthetic bilateral THA reduced the total cost of care (by 27%, p = 0.0001). In this matched cohort analysis, single-anesthetic bilateral THA was not associated with an increased risk of revision, reoperation, or postoperative complications, while decreasing cost. In our experience, single-anesthetic bilateral THA is a safe procedure that, for certain patients, offers an excellent means to deal with bilateral hip osteoarthritis. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The tensile effect on crack formation in single crystal silicon irradiated by intense pulsed ion beam

NASA Astrophysics Data System (ADS)

Liang, Guoying; Shen, Jie; Zhang, Jie; Zhong, Haowen; Cui, Xiaojun; Yan, Sha; Zhang, Xiaofu; Yu, Xiao; Le, Xiaoyun

2017-10-01

Improving antifatigue performance of silicon substrate is very important for the development of semiconductor industry. The cracking behavior of silicon under intense pulsed ion beam irradiation was studied by numerical simulation in order to understand the mechanism of induced surface peeling observed by experimental means. Using molecular dynamics simulation based on Stillinger Weber potential, tensile effect on crack growth and propagation in single crystal silicon was investigated. Simulation results reveal that stress-strain curves of single crystal silicon at a constant strain rate can be divided into three stages, which are not similar to metal stress-strain curves; different tensile load velocities induce difference of single silicon crack formation speed; the layered stress results in crack formation in single crystal silicon. It is concluded that the crack growth and propagation is more sensitive to strain rate, tensile load velocity, stress distribution in single crystal silicon.

EUS for the staging of gastric cancer: a meta-analysis.

PubMed

Mocellin, Simone; Marchet, Alberto; Nitti, Donato

2011-06-01

The role of EUS in the locoregional staging of gastric carcinoma is undefined. We aimed to comprehensively review and quantitatively summarize the available evidence on the staging performance of EUS. We systematically searched the MEDLINE, Cochrane, CANCERLIT, and EMBASE databases for relevant studies published until July 2010. Formal meta-analysis of diagnostic accuracy parameters was performed by using a bivariate random-effects model. Fifty-four studies enrolling 5601 patients with gastric cancer undergoing disease staging with EUS were eligible for the meta-analysis. EUS staging accuracy across eligible studies was measured by computing overall sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR). EUS can differentiate T1-2 from T3-4 gastric cancer with high accuracy, with overall sensitivity, specificity, PLR, NLR, and DOR of 0.86 (95% CI, 0.81-0.90), 0.91 (95% CI, 0.89-0.93), 9.8 (95% CI, 7.5-12.8), 0.15 (95% CI, 0.11-0.21), and 65 (95% CI, 41-105), respectively. In contrast, the diagnostic performance of EUS for lymph node status is less reliable, with overall sensitivity, specificity, PLR, NLR, and DOR of 0.69 (95% CI, 0.63-0.74), 0.84 (95% CI, 0.81-0.88), 4.4 (95% CI, 3.6-5.4), 0.37 (95% CI, 0.32-0.44), and 12 (95% CI, 9-16), respectively. Results regarding single T categories (including T1 substages) and Bayesian nomograms to calculate posttest probabilities for any target condition prevalence are also provided. Statistical heterogeneity was generally high; unfortunately, subgroup analysis did not identify a consistent source of the heterogeneity. Our results support the use of EUS for the locoregional staging of gastric cancer, which can affect the therapeutic management of these patients. However, clinicians must be aware of the performance limits of this staging tool. Copyright © 2011 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

Investigation of modification design of the fan stage in axial compressor

NASA Astrophysics Data System (ADS)

Zhou, Xun; Yan, Peigang; Han, Wanjin

2010-04-01

The S2 flow path design method of the transonic compressor is used to design the one stage fan in order to replace the original designed blade cascade which has two-stage transonic fan rotors. In the modification design, the camber line is parameterized by a quartic polynomial curve and the thickness distribution of the blade profile is controlled by the double-thrice polynomial. Therefore, the inlet flow has been pre-compressed and the location and intensity of the shock wave at supersonic area have been controlled in order to let the new blade profiles have better aerodynamic performance. The computational results show that the new single stage fan rotor increases the efficiency by two percent at the design condition and the total pressure ratio is slightly higher than that of the original design. At the same time, it also meets the mass flow rate and the geometrical size requirements for the modification design.

Comparison of oncological and functional outcomes of pure versus robotic-assisted laparoscopic radical prostatectomy performed by a single surgeon.

PubMed

Park, Bumsoo; Kim, Woojung; Jeong, Byong Chang; Jeon, Seong Soo; Lee, Hyun Moo; Choi, Han Yong; Seo, Seong Il

2013-02-01

The aim of this study was to compare oncological and functional outcomes of pure laparoscopic radical prostatectomy (LRP) and robotic-assisted laparoscopic radical prostatectomy (RALRP) performed by a single surgeon. In total, 327 consecutive patients with prostate cancer who underwent radical prostatectomy (144 with LRP and 183 with RALRP) were enrolled. No significant differences were found in prostate-specific antigen level, biopsy Gleason score, clinical T stage or D'Amico risk stratification between the two groups. The operating time was longer in the LRP group (p < 0.001). The RALRP group patients had significantly lower postoperative pain numerical rating scale (NRS) (p = 0.016) and catheter duration (p < 0.001). There were no differences in pathological Gleason score, pathological T stage or positive surgical margin rate. No differences were found in biochemical recurrence-free survival. Postoperative pad-free continence rates revealed a more rapid recovery in the RALRP group, but rates at 12 months were not significantly different. Multivariate analysis showed that the type of surgery was a strong independent factor to predict early postoperative pad use. Postoperative potency rates were not significantly different at 3, 6 and 12 months in patients who underwent nerve-sparing procedures. LRP and RALRP performed by a single surgeon yielded similar results in terms of safety and oncological outcomes. More favorable outcomes were noted in operating time, pain NRS and catheter duration, as well as urinary continence recovery time. Therefore, RALRP showed more favorable components in terms of postoperative quality of life than LRP.

Experimental Results of the First Two Stages of an Advanced Transonic Core Compressor Under Isolated and Multi-Stage Conditions

NASA Technical Reports Server (NTRS)

Prahst, Patricia S.; Kulkarni, Sameer; Sohn, Ki H.

2015-01-01

NASA's Environmentally Responsible Aviation (ERA) Program calls for investigation of the technology barriers associated with improved fuel efficiency of large gas turbine engines. Under ERA the task for a High Pressure Ratio Core Technology program calls for a higher overall pressure ratio of 60 to 70. This mean that the HPC would have to almost double in pressure ratio and keep its high level of efficiency. The challenge is how to match the corrected mass flow rate of the front two supersonic high reaction and high corrected tip speed stages with a total pressure ratio of 3.5. NASA and GE teamed to address this challenge by using the initial geometry of an advanced GE compressor design to meet the requirements of the first 2 stages of the very high pressure ratio core compressor. The rig was configured to run as a 2 stage machine, with Strut and IGV, Rotor 1 and Stator 1 run as independent tests which were then followed by adding the second stage. The goal is to fully understand the stage performances under isolated and multi-stage conditions and fully understand any differences and provide a detailed aerodynamic data set for CFD validation. Full use was made of steady and unsteady measurement methods to isolate fluid dynamics loss source mechanisms due to interaction and endwalls. The paper will present the description of the compressor test article, its predicted performance and operability, and the experimental results for both the single stage and two stage configurations. We focus the detailed measurements on 97 and 100 of design speed at 3 vane setting angles.

Modeling and Validation of a Three-Stage Solidification Model for Sprays

NASA Astrophysics Data System (ADS)

Tanner, Franz X.; Feigl, Kathleen; Windhab, Erich J.

2010-09-01

A three-stage freezing model and its validation are presented. In the first stage, the cooling of the droplet down to the freezing temperature is described as a convective heat transfer process in turbulent flow. In the second stage, when the droplet has reached the freezing temperature, the solidification process is initiated via nucleation and crystal growth. The latent heat release is related to the amount of heat convected away from the droplet and the rate of solidification is expressed with a freezing progress variable. After completion of the solidification process, in stage three, the cooling of the solidified droplet (particle) is described again by a convective heat transfer process until the particle approaches the temperature of the gaseous environment. The model has been validated by experimental data of a single cocoa butter droplet suspended in air. The subsequent spray validations have been performed with data obtained from a cocoa butter melt in an experimental spray tower using the open-source computational fluid dynamics code KIVA-3.

Object-based detection of vehicles using combined optical and elevation data

NASA Astrophysics Data System (ADS)

Schilling, Hendrik; Bulatov, Dimitri; Middelmann, Wolfgang

2018-02-01

The detection of vehicles is an important and challenging topic that is relevant for many applications. In this work, we present a workflow that utilizes optical and elevation data to detect vehicles in remotely sensed urban data. This workflow consists of three consecutive stages: candidate identification, classification, and single vehicle extraction. Unlike in most previous approaches, fusion of both data sources is strongly pursued at all stages. While the first stage utilizes the fact that most man-made objects are rectangular in shape, the second and third stages employ machine learning techniques combined with specific features. The stages are designed to handle multiple sensor input, which results in a significant improvement. A detailed evaluation shows the benefits of our workflow, which includes hand-tailored features; even in comparison with classification approaches based on Convolutional Neural Networks, which are state of the art in computer vision, we could obtain a comparable or superior performance (F1 score of 0.96-0.94).

Self-assembly of single-wall carbon nanotubes during the cooling process of hot carbon gas.

PubMed

Wen, Yushi; Zheng, Ke; Long, Xinping; Li, Ming; Xue, Xianggui; Dai, Xiaogan; Deng, Chuan

2018-04-25

In this work, self-assembly mechanism of single-wall carbon nanotube (SWCNT) during the annealing process of hot gaseous carbon is presented using reactive force field (ReaxFF)-based reactive molecular simulations. A series of simulations were performed on the evolution of reactive carbon gas. The simulation results show that the reactive carbon gas can be assembled into regular SWCNT without a catalyst. Five distinct stages of SWCNT self-assembly are proposed. For some initial configurations, the CNT was found to spin at an ultra-high rate after the nucleation. Graphical abstract Self-assembly process of single-wall carbon nanotube from the annealing of hot gaseous carbon.

MMIC DHBT Common-Base Amplifier for 172 GHz

NASA Technical Reports Server (NTRS)

Paidi, Vamsi; Griffith, Zack; Wei, Yun; Dahlstrom, Mttias; Urteaga, Miguel; Rodwell, Mark; Samoska, Lorene; Fung, King Man; Schlecht, Erich

2006-01-01

Figure 1 shows a single-stage monolithic microwave integrated circuit (MMIC) power amplifier in which the gain element is a double-heterojunction bipolar transistor (DHBT) connected in common-base configuration. This amplifier, which has been demonstrated to function well at a frequency of 172 GHz, is part of a continuing effort to develop compact, efficient amplifiers for scientific instrumentation, wide-band communication systems, and radar systems that will operate at frequencies up to and beyond 180 GHz. The transistor is fabricated from a layered structure formed by molecular beam epitaxy in the InP/InGaAs material system. A highly doped InGaAs base layer and a collector layer are fabricated from the layered structure in a triple mesa process. The transistor includes two separate emitter fingers, each having dimensions of 0.8 by 12 m. The common-base configuration was chosen for its high maximum stable gain in the frequency band of interest. The input-matching network is designed for high bandwidth. The output of the transistor is matched to a load line for maximum saturated output power under large-signal conditions, rather than being matched for maximum gain under small-signal conditions. In a test at a frequency of 172 GHz, the amplifier was found to generate an output power of 7.5 mW, with approximately 5 dB of large-signal gain (see Figure 2). Moreover, the amplifier exhibited a peak small-signal gain of 7 dB at a frequency of 176 GHz. This performance of this MMIC single-stage amplifier containing only a single transistor represents a significant advance in the state of the art, in that it rivals the 170-GHz performance of a prior MMIC three-stage, four-transistor amplifier. [The prior amplifier was reported in "MMIC HEMT Power Amplifier for 140 to 170 GHz" (NPO-30127), NASA Tech Briefs, Vol. 27, No. 11 (November 2003), page 49.] This amplifier is the first heterojunction- bipolar-transistor (HBT) amplifier built for medium power operation in this frequency band. The performance of the amplifier as measured in the aforementioned tests suggests that InP/InGaAs HBTs may be superior to high-electron-mobility (HEMT) transistors in that the HBTs may offer more gain per stage and more output power per transistor.

Secondary plasma formation after single pulse laser ablation underwater and its advantages for laser induced breakdown spectroscopy (LIBS).

PubMed

Gavrilović, M R; Cvejić, M; Lazic, V; Jovićević, S

2016-06-07

In this work we present studies of spatial and temporal plasma evolution after single pulse ablation of an aluminium target in water. The laser ablation was performed using 20 ns long pulses emitted at 1064 nm. The plasma characterization was performed by fast photography, the Schlieren technique, shadowgraphy and optical emission spectroscopy. The experimental results indicate the existence of two distinct plasma stages: the first stage has a duration of approximately 500 ns from the laser pulse, and is followed by a new plasma growth starting from the crater center. The secondary plasma slowly evolves inside the growing vapor bubble, and its optical emission lasts over several tens of microseconds. Later, the hot glowing particles, trapped inside the vapor cavity, were detected during the whole cycle of the bubble, where the first collapse occurs after 475 μs from the laser pulse. Differences in the plasma properties during the two evolution phases are discussed, with an accent on the optical emission since its detection is of primary importance for LIBS. Here we demonstrate that the LIBS signal quality in single pulse excitation underwater can be greatly enhanced by detecting only the secondary plasma emission, and also by applying long acquisition gates (in the order of 10-100 μs). The presented results are of great importance for LIBS measurements inside a liquid environment, since they prove that a good analytical signal can be obtained by using nanosecond pulses from a single commercial laser source and by employing cost effective, not gated detectors.

Is knowledge translation adequate? A quality assurance study of staging investigations in early stage breast cancer patients.

PubMed

Han, Dolly; Hogeveen, Sophie; Sweet Goldstein, Miriam; George, Ralph; Brezden-Masley, Christine; Hoch, Jeffrey; Haq, Rashida; Simmons, Christine E

2012-02-01

After primary surgery, patients diagnosed with early stage breast cancer undergo radiological investigations based on pathologic stage of disease to rule out distant metastases. Published guidelines can aid clinicians in determining which tests are appropriate based on stage of disease. We wished to assess the consistency of radiological staging in an academic community oncology setting with standard guidelines and to determine the overall impact of non-adherence to these guidelines. A retrospective cohort study was conducted for new breast cancer patients seen at a single institution between January 2009 and April 2010. Patients were included if initial diagnosis and primary surgery was at this institution. Pathologic stage and radiological tests completed were recorded. A literature review was performed and the results were compared with those from this study to determine overall adherence rates. Subsequently, a cost analysis was performed to determine the financial impact at this centre. 231 patients met eligibility criteria for inclusion in this study. A large proportion of patients were over-staged with 129 patients (55%) undergoing unnecessary investigations according to guidelines. Specifically, 59% of stage I patients and 58% of stage II patients were over-investigated. Distant metastases at the time of diagnosis were found in three patients, all of whom had stage III disease (1.3%). The literature reviewed revealed similar non-adherence rates in other centres. The estimated cost of such non-adherence is in the range of $78 (CDN) per new early stage breast cancer patient seen at this centre. This oncology centre has a low adherence to practice guidelines for staging investigations in breast cancer patients, with 55% of patients undergoing unnecessary tests. Very few patients had metastases at diagnosis, and all had pathological stage III disease. Efforts may need to focus on improving knowledge translation across clinical oncology settings to increase guideline adherence.

A parametric sensitivity study for single-stage-to-orbit hypersonic vehicles using trajectory optimization

NASA Astrophysics Data System (ADS)

Lovell, T. Alan; Schmidt, D. K.

1994-03-01

The class of hypersonic vehicle configurations with single stage-to-orbit (SSTO) capability reflect highly integrated airframe and propulsion systems. These designs are also known to exhibit a large degree of interaction between the airframe and engine dynamics. Consequently, even simplified hypersonic models are characterized by tightly coupled nonlinear equations of motion. In addition, hypersonic SSTO vehicles present a major system design challenge; the vehicle's overall mission performance is a function of its subsystem efficiencies including structural, aerodynamic, propulsive, and operational. Further, all subsystem efficiencies are interrelated, hence, independent optimization of the subsystems is not likely to lead to an optimum design. Thus, it is desired to know the effect of various subsystem efficiencies on overall mission performance. For the purposes of this analysis, mission performance will be measured in terms of the payload weight inserted into orbit. In this report, a trajectory optimization problem is formulated for a generic hypersonic lifting body for a specified orbit-injection mission. A solution method is outlined, and results are detailed for the generic vehicle, referred to as the baseline model. After evaluating the performance of the baseline model, a sensitivity study is presented to determine the effect of various subsystem efficiencies on mission performance. This consists of performing a parametric analysis of the basic design parameters, generating a matrix of configurations, and determining the mission performance of each configuration. Also, the performance loss due to constraining the total head load experienced by the vehicle is evaluated. The key results from this analysis include the formulation of the sizing problem for this vehicle class using trajectory optimization, characteristics of the optimal trajectories, and the subsystem design sensitivities.

A parametric sensitivity study for single-stage-to-orbit hypersonic vehicles using trajectory optimization

NASA Technical Reports Server (NTRS)

Lovell, T. Alan; Schmidt, D. K.

1994-01-01

The class of hypersonic vehicle configurations with single stage-to-orbit (SSTO) capability reflect highly integrated airframe and propulsion systems. These designs are also known to exhibit a large degree of interaction between the airframe and engine dynamics. Consequently, even simplified hypersonic models are characterized by tightly coupled nonlinear equations of motion. In addition, hypersonic SSTO vehicles present a major system design challenge; the vehicle's overall mission performance is a function of its subsystem efficiencies including structural, aerodynamic, propulsive, and operational. Further, all subsystem efficiencies are interrelated, hence, independent optimization of the subsystems is not likely to lead to an optimum design. Thus, it is desired to know the effect of various subsystem efficiencies on overall mission performance. For the purposes of this analysis, mission performance will be measured in terms of the payload weight inserted into orbit. In this report, a trajectory optimization problem is formulated for a generic hypersonic lifting body for a specified orbit-injection mission. A solution method is outlined, and results are detailed for the generic vehicle, referred to as the baseline model. After evaluating the performance of the baseline model, a sensitivity study is presented to determine the effect of various subsystem efficiencies on mission performance. This consists of performing a parametric analysis of the basic design parameters, generating a matrix of configurations, and determining the mission performance of each configuration. Also, the performance loss due to constraining the total head load experienced by the vehicle is evaluated. The key results from this analysis include the formulation of the sizing problem for this vehicle class using trajectory optimization, characteristics of the optimal trajectories, and the subsystem design sensitivities.

An analysis on combined GPS/COMPASS data quality and its effect on single point positioning accuracy under different observing conditions

NASA Astrophysics Data System (ADS)

Cai, Changsheng; Gao, Yang; Pan, Lin; Dai, Wujiao

2014-09-01

With the rapid development of the COMPASS system, it is currently capable of providing regional navigation services. In order to test its data quality and performance for single point positioning (SPP), experiments have been conducted under different observing conditions including open sky, under trees, nearby a glass wall, nearby a large area of water, under high-voltage lines and under a signal transmitting tower. To assess the COMPASS data quality, the code multipath, cycle slip occurrence rate and data availability were analyzed and compared to GPS data. The datasets obtained from the experiments have also been utilized to perform combined GPS/COMPASS SPP on an epoch-by-epoch basis using unsmoothed single-frequency code observations. The investigation on the regional navigation performance aims at low-accuracy applications and all tests are made in Changsha, China, using the “SOUTH S82-C” GPS/COMPASS receivers. The results show that adding COMPASS observations can significantly improve the positioning accuracy of single-frequency GPS-only SPP in environments with limited satellite visibility. Since the COMPASS system is still in an initial operational stage, all results are obtained based on a fairly limited amount of data.

Ambient temperature cadmium zinc telluride radiation detector and amplifier circuit

DOEpatents

McQuaid, James H.; Lavietes, Anthony D.

1998-05-29

A low noise, low power consumption, compact, ambient temperature signal amplifier for a Cadmium Zinc Telluride (CZT) radiation detector. The amplifier can be used within a larger system (e.g., including a multi-channel analyzer) to allow isotopic analysis of radionuclides in the field. In one embodiment, the circuit stages of the low power, low noise amplifier are constructed using integrated circuit (IC) amplifiers , rather than discrete components, and include a very low noise, high gain, high bandwidth dual part preamplification stage, an amplification stage, and an filter stage. The low noise, low power consumption, compact, ambient temperature amplifier enables the CZT detector to achieve both the efficiency required to determine the presence of radio nuclides and the resolution necessary to perform isotopic analysis to perform nuclear material identification. The present low noise, low power, compact, ambient temperature amplifier enables a CZT detector to achieve resolution of less than 3% full width at half maximum at 122 keV for a Cobalt-57 isotope source. By using IC circuits and using only a single 12 volt supply and ground, the novel amplifier provides significant power savings and is well suited for prolonged portable in-field use and does not require heavy, bulky power supply components.

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

PubMed

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

2017-04-12

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

Multicolor Bioluminescence Boosts Malaria Research: Quantitative Dual-Color Assay and Single-Cell Imaging in Plasmodium falciparum Parasites

PubMed Central

2015-01-01

New reliable and cost-effective antimalarial drug screening assays are urgently needed to identify drugs acting on different stages of the parasite Plasmodium falciparum, and particularly those responsible for human-to-mosquito transmission, that is, the P. falciparum gametocytes. Low Z′ factors, narrow dynamic ranges, and/or extended assay times are commonly reported in current gametocyte assays measuring gametocyte-expressed fluorescent or luciferase reporters, endogenous ATP levels, activity of gametocyte enzymes, or redox-dependent dye fluorescence. We hereby report on a dual-luciferase gametocyte assay with immature and mature P. falciparum gametocyte stages expressing red and green-emitting luciferases from Pyrophorus plagiophthalamus under the control of the parasite sexual stage-specific pfs16 gene promoter. The assay was validated with reference antimalarial drugs and allowed to quantitatively and simultaneously measure stage-specific drug effects on parasites at different developmental stages. The optimized assay, requiring only 48 h incubation with drugs and using a cost-effective luminogenic substrate, significantly reduces assay cost and time in comparison to state-of-the-art analogous assays. The assay had a Z′ factor of 0.71 ± 0.03, and it is suitable for implementation in 96- and 384-well microplate formats. Moreover, the use of a nonlysing d-luciferin substrate significantly improved the reliability of the assay and allowed one to perform, for the first time, P. falciparum bioluminescence imaging at single-cell level. PMID:25102353

Harnessing Teams and Technology to Improve Outcomes in Infants With Single Ventricle.

PubMed

Shirali, Girish; Erickson, Lori; Apperson, Jonathan; Goggin, Kathy; Williams, David; Reid, Kimberly; Bradley-Ewing, Andrea; Tucker, Dawn; Bingler, Michael; Spertus, John; Rabbitt, Leslie; Stroup, Richard

2016-05-01

Infants with single ventricle require staged cardiac surgery, with stage I typically performed shortly after birth, stage II at 4 to 6 months of age, and stage III at 3 to 5 years of age. There is a high risk of interstage mortality and morbidity after infants are discharged from the hospital between stages I and II. Traditional home monitoring requires caregivers to record measurements of weight and oxygen saturation into a binder and requires families to assume a surveillance role. We have developed a tablet PC-based solution that provides secure and nearly instantaneous transfer of patient information to a cloud-based server, with the capacity for instant alerts to be sent to the caregiver team. The cloud-based IT infrastructure lends itself well to being able to be scaled to multiple sites while maintaining strict control over the privacy of each site. All transmitted data are transferred to the electronic medical record daily. The system conforms to recently released Food and Drug Administration regulation that pertains to mobile health technologies and devices. Since this platform was developed in March 2014, 30 patients have been monitored. There have been no interstage deaths. The experience of care providers has been unanimously positive. The addition of video has added to the use of the monitoring program. Of 30 families, 23 expressed a preference for the tablet PC over the notebook, 3 had no preference, and 4 preferred the notebook to the tablet PC. © 2016 American Heart Association, Inc.

Parallel Distributed Processing and Lexical-Semantic Effects in Visual Word Recognition: Are a Few Stages Necessary?

ERIC Educational Resources Information Center

Borowsky, Ron; Besner, Derek

2006-01-01

D. C. Plaut and J. R. Booth presented a parallel distributed processing model that purports to simulate human lexical decision performance. This model (and D. C. Plaut, 1995) offers a single mechanism account of the pattern of factor effects on reaction time (RT) between semantic priming, word frequency, and stimulus quality without requiring a…

Feasibility of a responsive, hybrid propulsion augmented, Vertical-Takeoff-and-Landing, Single-Stage-to-Orbit launch system

NASA Astrophysics Data System (ADS)

Pelaccio, Dennis G.

1996-03-01

A novel, reusable, Vertical-Takeoff-and-Landing, Single-Stage-to-Orbit (VTOL/SSTO) launch system concept, named HYP-SSTO, is presented in this paper. This launch vehicle system concept uses a highly coupled, main high performance liquid oxygen/liquid hydrogen (LOX/LH2) propulsion system, that is used only for launch, with a hybrid auxiliary propulsion system which is used during final orbit insertion, major orbit maneuvering, and landing propulsive burn phases of flight. By using a hybrid propulsion system for major orbit maneuver burns and landing, this launch system concept has many advantages over conventional VTOL/SSTO concepts that use LOX/LH2 propulsion system(s) burns for all phases of flight. Because hybrid propulsion systems are relatively simple and inert by their nature, this concept has the potential to support short turnaround times between launches, be economical to develop, and be competitive in terms of overall system life-cycle cost. This paper provides a technical description of the novel, reusable HYP-SSTO launch system concept. Launch capability performance, as well as major design and operational system attributes, are identified and discussed.

Fibular free flap reconstruction for the management of advanced bilateral mandibular osteoradionecrosis.

PubMed

Shan, Xiao-Feng; Li, Ru-Huang; Lu, Xu-Guang; Cai, Zhi-Gang; Zhang, Jie; Zhang, Jian-Guo

2015-03-01

Fibular osteoseptocutaneous flap has been widely used for unilateral mandibular reconstruction. However, reports about the effects of fibular osteoseptocutaneous flap for the reconstruction of bilateral mandibular defects are limited. In this study, we used free vascularized fibular flaps to successfully manage bilateral mandibular osteoradionecrosis(ORN) in 5 patients. Functional aspects were evaluated during the reconstruction process. All 5 patients had bilateral refractory ORN of the mandible and underwent radical resection between 2003 and 2011. The reconstruction surgery was performed in 2 stages using 2 free fibular flaps in 3 patients. In the other 2 patients, reconstruction was performed in a single stage using 2 separate flaps prepared from a single fibula. All patients had a healthy mandibular symphysis and meniscus of the temporomandibular joint, and these structures were preserved during the reconstruction.Of the 10 defects involving the mandible sides, 9 were successfully reconstructed. One microvascular composite flap failed because of radiation injury to the arterial endothelium at the recipient site. After the treatments, all patients had good esthetic and functional outcomes. Preoperative clinical features such as trismus and dysphagia were also markedly improved. Our surgical method may be an effective alternative for the clinical management of advanced bilateral mandibular ORN.

Singer's preferred acoustic condition in performance in an opera house and self-perception of the singer's voice

NASA Astrophysics Data System (ADS)

Noson, Dennis; Kato, Kosuke; Ando, Yoichi

2004-05-01

Solo singers have been shown to over estimate the relative sound pressure level of a delayed, external reproduction of their own voice, singing single syllables, which, in turn, appears to influence the preferred delay of simulated stage reflections [Noson, Ph.D. thesis, Kobe University, 2003]. Bone conduction is thought to be one factor separating singer versus instrumental performer judgments of stage acoustics. Using a parameter derived from the vocal signal autocorrelation function (ACF envelope), the changes in singer preference for delayed reflections is primarily explained by the ACF parameter, rather than internal bone conduction. An auditory model of a singer's preferred reflection delay is proposed, combining the effects of acoustical environment (reflection amplitude), bone conduction, and performer vocal overestimate, which may be applied to the acoustic design of reflecting elements in both upstage and forestage environments of opera stages. For example, soloists who characteristically underestimate external voice levels (or overestimate their own voice) should be provided shorter distances to reflective panels-irrespective of their singing style. Adjustable elements can be deployed to adapt opera houses intended for bel canto style performances to other styles. Additional examples will also be discussed. a)Now at Kumamoto Univ., Kumamoto, Japan. b)Now at: 1-10-27 Yamano Kami, Kumamoto, Japan.

Conceptual Knowledge Influences Decision Making Differently in Individuals with High or Low Cognitive Flexibility: An ERP Study.

PubMed

Dong, Xiaofei; Du, Xiumin; Qi, Bing

2016-01-01

Studies using the Iowa Gambling Task (IGT) have distinguished between good and bad decision makers and have provided an explanation for deficits in decision making. Previous studies have demonstrated a link between Wisconsin Card Sorting Test (WCST) performance and IGT performance, but the results were not consistent and failed to explain why WCST performance can predict IGT performance. The present study aimed to demonstrate that WCST performance can predict IGT performance and to identify the cognitive component of the WCST that affects IGT performance using event-related potentials (ERPs). In this study, 39 healthy subjects (5 subjects were excluded) were divided into a high group and a low group based on their global score on the WCST. A single-choice version of the IGT was used to eliminate the impact of retrieval strategies on the choice evaluation process and interference due to uncorrelated decks. Differences in the underlying neural mechanisms and explicit knowledge between the two groups during the three stages of the decision-making process were described. Based on the information processing perspective, we divided the decision-making process into three stages: choice evaluation, response selection, and feedback processing. The behavioral results showed that the highly cognitively flexible participants performed better on the IGT and acquired more knowledge of the task. The ERP results showed that during the choice evaluation stage, the P300 recorded from central and parietal regions when a bad deck appeared was larger in the high group participants than in the low group participants. During the response selection stage, the effect of choice type was significant only in the frontal region in the high group, with a larger effect for passing. During the feedback evaluation stage, a larger FRN was evoked for a loss than for a win in the high group, whereas the FRN effect was absent in the low group. Compared with the participants with low cognitive flexibility, the participants with high cognitive flexibility performed better on the IGT, acquired more knowledge of the task, and displayed more obvious somatic markers. The low group participants showed reduced working memory abilities during the choice evaluation stage. The appropriate somatic markers reflected by the DPN is formed only when conceptual knowledge is gained in the response selection stage. The absence of an FRN effect in the subjects who performed poorly on the WCST suggests a significant deficit in feedback learning and reward prediction.

Conceptual Knowledge Influences Decision Making Differently in Individuals with High or Low Cognitive Flexibility: An ERP Study

PubMed Central

Dong, Xiaofei; Du, Xiumin; Qi, Bing

2016-01-01

Objective Studies using the Iowa Gambling Task (IGT) have distinguished between good and bad decision makers and have provided an explanation for deficits in decision making. Previous studies have demonstrated a link between Wisconsin Card Sorting Test (WCST) performance and IGT performance, but the results were not consistent and failed to explain why WCST performance can predict IGT performance. The present study aimed to demonstrate that WCST performance can predict IGT performance and to identify the cognitive component of the WCST that affects IGT performance using event-related potentials (ERPs). Methods In this study, 39 healthy subjects (5 subjects were excluded) were divided into a high group and a low group based on their global score on the WCST. A single-choice version of the IGT was used to eliminate the impact of retrieval strategies on the choice evaluation process and interference due to uncorrelated decks. Differences in the underlying neural mechanisms and explicit knowledge between the two groups during the three stages of the decision-making process were described. Results Based on the information processing perspective, we divided the decision-making process into three stages: choice evaluation, response selection, and feedback processing. The behavioral results showed that the highly cognitively flexible participants performed better on the IGT and acquired more knowledge of the task. The ERP results showed that during the choice evaluation stage, the P300 recorded from central and parietal regions when a bad deck appeared was larger in the high group participants than in the low group participants. During the response selection stage, the effect of choice type was significant only in the frontal region in the high group, with a larger effect for passing. During the feedback evaluation stage, a larger FRN was evoked for a loss than for a win in the high group, whereas the FRN effect was absent in the low group. Conclusion Compared with the participants with low cognitive flexibility, the participants with high cognitive flexibility performed better on the IGT, acquired more knowledge of the task, and displayed more obvious somatic markers. The low group participants showed reduced working memory abilities during the choice evaluation stage. The appropriate somatic markers reflected by the DPN is formed only when conceptual knowledge is gained in the response selection stage. The absence of an FRN effect in the subjects who performed poorly on the WCST suggests a significant deficit in feedback learning and reward prediction. PMID:27479484

Engine/vehicle integration for vertical takeoff and landing single stage to orbit vehicles

NASA Astrophysics Data System (ADS)

Weegar, R. K.

1992-08-01

SSTO vehicles design which is currently being developed under the Single Stage Rocket Technology program of the Strategic Defense Initiative Organization is discussed. Particular attention is given to engine optimization and integration of ascent, orbital, and landing propulsion requirements into a single system.

Performance of a RBCC Engine in Rocket-Operation

NASA Astrophysics Data System (ADS)

Tomioka, Sadatake; Kubo, Takahiro; Noboru Sakuranaka; Tani, Koichiro

Combination of a scramjet (supersonic combustion ramjet) flow-pass with embedded rocket engines (the combined system termed as Rocket-based Combined Cycle engine) are expected to be the most effective propulsion system for space launch vehicles. Either SSTO (Single Stage To Orbit) system or TSTO (Two Stage To Orbit) system with separation at high altitude needs final stage acceleration in space, so that the RBCC (Rocket Based Combined Cycle) engine should be operated as rocket engines. Performance of the scramjet combustor as the extension to the rocket nozzle, was experimentally evaluated by injecting inert gas at various pressure through the embedded rocket chamber while the whole sub-scaled model was placed in a low pressure chamber connected to an air-driven ejector system. The results showed that the thrust coefficient was about 1.2, the low value being found to mainly due to the friction force on the scramjet combustor wall, while blocking the scramjet flow pass’s opening to increase nozzle extension thrust surface, was found to have little effects on the thrust performance. The combustor was shortened to reduce the friction loss, however, degree of reduction was limited as friction decreased rapidly with distance from the onset of the scramjet combustor.

Hybrid video-assisted thoracic surgery with segmental-main bronchial sleeve resection for non-small cell lung cancer.

PubMed

Li, Shuben; Chai, Huiping; Huang, Jun; Zeng, Guangqiao; Shao, Wenlong; He, Jianxing

2014-04-01

The purpose of the current study is to present the clinical and surgical results in patients who underwent hybrid video-assisted thoracic surgery with segmental-main bronchial sleeve resection. Thirty-one patients, 27 men and 4 women, underwent segmental-main bronchial sleeve anastomoses for non-small cell lung cancer between May 2004 and May 2011. Twenty-six (83.9%) patients had squamous cell carcinoma, and 5 patients had adenocarcinoma. Six patients were at stage IIB, 24 patients at stage IIIA, and 1 patient at stage IIIB. Secondary sleeve anastomosis was performed in 18 patients, and Y-shaped multiple sleeve anastomosis was performed in 8 patients. Single segmental bronchiole anastomosis was performed in 5 cases. The average time for chest tube removal was 5.6 days. The average length of hospital stay was 11.8 days. No anastomosis fistula developed in any of the patients. The 1-, 2-, and 3-year survival rates were 83.9%, 71.0%, and 41.9%, respectively. Hybrid video-assisted thoracic surgery with segmental-main bronchial sleeve resection is a complex technique that requires training and experience, but it is an effective and safe operation for selected patients.

Computational analysis of a multistage axial compressor

NASA Astrophysics Data System (ADS)

Mamidoju, Chaithanya

Turbomachines are used extensively in Aerospace, Power Generation, and Oil & Gas Industries. Efficiency of these machines is often an important factor and has led to the continuous effort to improve the design to achieve better efficiency. The axial flow compressor is a major component in a gas turbine with the turbine's overall performance depending strongly on compressor performance. Traditional analysis of axial compressors involves throughflow calculations, isolated blade passage analysis, Quasi-3D blade-to-blade analysis, single-stage (rotor-stator) analysis, and multi-stage analysis involving larger design cycles. In the current study, the detailed flow through a 15 stage axial compressor is analyzed using a 3-D Navier Stokes CFD solver in a parallel computing environment. Methodology is described for steady state (frozen rotor stator) analysis of one blade passage per component. Various effects such as mesh type and density, boundary conditions, tip clearance and numerical issues such as turbulence model choice, advection model choice, and parallel processing performance are analyzed. A high sensitivity of the predictions to the above was found. Physical explanation to the flow features observed in the computational study are given. The total pressure rise verses mass flow rate was computed.

Single-stage laparoscopic common bile duct exploration and cholecystectomy versus two-stage endoscopic stone extraction followed by laparoscopic cholecystectomy for patients with gallbladder stones with common bile duct stones: systematic review and meta-analysis of randomized trials with trial sequential analysis.

PubMed

Singh, Anand Narayan; Kilambi, Ragini

2018-03-30

The ideal management of common bile duct (CBD) stones associated with gall stones is a matter of debate. We planned a meta-analysis of randomized trials comparing single-stage laparoscopic CBD exploration and cholecystectomy (LCBDE) with two-stage preoperative endoscopic stone extraction followed by cholecystectomy (ERCP + LC). We searched the Pubmed/Medline, Web of science, Science citation index, Google scholar and Cochrane Central Register of Controlled trials electronic databases till June 2017 for all English language randomized trials comparing the two approaches. Statistical analysis was performed using Review Manager (RevMan) [Computer program], Version 5.3. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014 and results were expressed as odds ratio for dichotomous variables and mean difference for continuous. p value ≤ 0.05 was considered significant. Trial sequential analysis (TSA) was performed using TSA version 0.9.5.5 (Copenhagen: The Copenhagen Trial Unit, Centre for Clinical Intervention Research, 2016). PROSPERO trial registration number is CRD42017074673. A total of 11 trials were included in the analysis, with a total of 1513 patients (751-LCBDE; 762-ERCP + LC). LCBDE was found to have significantly lower rates of technical failure [OR 0.59, 95% CI (0.38, 0.93), p = 0.02] and shorter hospital stay [MD - 1.63, 95% CI (- 3.23, - 0.03), p = 0.05]. There was no significant difference in mortality [OR 0.37, 95% CI (0.09, 1.51), p = 0.17], morbidity [OR 0.97, 95% CI (0.70, 1.33), p = 0.84], cost [MD - 379.13, 95% CI (- 784.80, 111.2), p = 0.13] or recurrent/retained stones [OR 1.01, 95% CI (0.38, 2.73), p = 0.98]. TSA showed that although the Z-curve crossed the boundaries of conventional significance, the estimated information size is yet to be achieved. Single-stage LCBDE is superior to ERCP + LC in terms of technical success and shorter hospital stay in good-risk patients with gallstones and CBD stones, where expertise, operative time and instruments are available.

Laryngotracheal Stenosis in Children and Infants With Neurological Disorders: Management and Outcome.

PubMed

Nicollas, Richard; Moreddu, Eric; Le Treut-Gay, Claire; Roman, Stéphane; Mancini, Julien; Triglia, Jean-Michel

2016-12-01

The goal of this retrospective study is to compare the management and outcome of surgical treatment of laryngotracheal stenosis in children and infants with and without an associated neurological disorder. In a series of children operated on for subglottic stenosis (SGS), patients with an associated neurological disorder were identified. The following criteria were compared in children with and without neurological disease: grade of stenosis, age, technique (Crico-Tracheal Resection (CTR), Laryngo-Tracheo-Plasty (LTP) in single and 2 stage, laser), analyzing duration, preoperative tracheostomy, decannulation rate, preoperative gastrostomy, and number of days in intensive care unit and in hospital. Two hundred twenty-three children were operated on for subglottic stenosis, of whom 68 (30.5%) had an associated neurological disorder. Some criteria were found to be statistically different between the 2 populations: mean age of 43 months in neurological population versus 13 months (P < .001). The distribution of the grades of SGS appeared similar in the 2 groups (P = .088), and the mean duration of stay in hospital and in ICU were not statistically different (respectively, P = .186 and P = .056) between the 2 groups; a 2-stage procedure was performed more frequently than 1-stage in the cases with associated neurological disorder-66.6% versus 36.5% (P = .013); the median duration of stenting was 20 days in those with neurological disease versus 12 (P = .021). Preoperative tracheotomy was noted in 75% of neurological patients versus 47.7% of the others (P < .001). The outcome was considered to be good (decannulation and no further treatment) following a single procedure in 82.4% of patients with neurological disorder, as against 86.5% of neurologically unimpaired subjects. The difference in outcome of surgery was not statistically different (P = .392) between the 2 groups. It appears that subglottic stenosis in children with associated neurological disorder is not more severe than in neurologically normal patients. In three-quarters of the neurologically impaired cases, a preoperative tracheostomy was needed, but the rates of failure of postoperative decannulation are not statistically significant between the 2 groups. In our experience, 2-stage techniques are more often performed than single stage in this population in order to allow airway safety, for example after feeding. If properly managed, the final results are similar in the 2 populations. © The Author(s) 2016.

Impairments of Motor Function While Multitasking in HIV

PubMed Central

Kronemer, Sharif I.; Mandel, Jordan A.; Sacktor, Ned C.; Marvel, Cherie L.

2017-01-01

Human immunodeficiency virus (HIV) became a treatable illness with the introduction of combination antiretroviral therapy (CART). As a result, patients with regular access to CART are expected to live decades with HIV. Long-term HIV infection presents unique challenges, including neurocognitive impairments defined by three major stages of HIV-associated neurocognitive disorders (HAND). The current investigation aimed to study cognitive and motor impairments in HIV using a novel multitasking paradigm. Unlike current standard measures of cognitive and motor performance in HIV, multitasking increases real-world validity by mimicking the dual motor and cognitive demands that are part of daily professional and personal settings (e.g., driving, typing and writing). Moreover, multitask assessments can unmask compensatory mechanisms, normally used under single task conditions, to maintain performance. This investigation revealed that HIV+ participants were impaired on the motor component of the multitask, while cognitive performance was spared. A patient-specific positive interaction between motor performance and working memory recall was driven by poor HIV+ multitaskers. Surprisingly, HAND stage did not correspond with multitask performance and a variety of commonly used assessments indicated normal motor function among HIV+ participants with poor motor performance during the experimental task. These results support the use of multitasks to reveal otherwise hidden impairment in chronic HIV by expanding the sensitivity of clinical assessments used to determine HAND stage. Future studies should examine the capability of multitasks to predict performance in personal, professional and health-related behaviors and prognosis of patients living with chronic HIV. PMID:28503143

Impairments of Motor Function While Multitasking in HIV.

PubMed

Kronemer, Sharif I; Mandel, Jordan A; Sacktor, Ned C; Marvel, Cherie L

2017-01-01

Human immunodeficiency virus (HIV) became a treatable illness with the introduction of combination antiretroviral therapy (CART). As a result, patients with regular access to CART are expected to live decades with HIV. Long-term HIV infection presents unique challenges, including neurocognitive impairments defined by three major stages of HIV-associated neurocognitive disorders (HAND). The current investigation aimed to study cognitive and motor impairments in HIV using a novel multitasking paradigm. Unlike current standard measures of cognitive and motor performance in HIV, multitasking increases real-world validity by mimicking the dual motor and cognitive demands that are part of daily professional and personal settings (e.g., driving, typing and writing). Moreover, multitask assessments can unmask compensatory mechanisms, normally used under single task conditions, to maintain performance. This investigation revealed that HIV+ participants were impaired on the motor component of the multitask, while cognitive performance was spared. A patient-specific positive interaction between motor performance and working memory recall was driven by poor HIV+ multitaskers. Surprisingly, HAND stage did not correspond with multitask performance and a variety of commonly used assessments indicated normal motor function among HIV+ participants with poor motor performance during the experimental task. These results support the use of multitasks to reveal otherwise hidden impairment in chronic HIV by expanding the sensitivity of clinical assessments used to determine HAND stage. Future studies should examine the capability of multitasks to predict performance in personal, professional and health-related behaviors and prognosis of patients living with chronic HIV.

Retention of laparoscopic and robotic skills among medical students: a randomized controlled trial.

PubMed

Orlando, Megan S; Thomaier, Lauren; Abernethy, Melinda G; Chen, Chi Chiung Grace

2017-08-01

Although simulation training beneficially contributes to traditional surgical training, there are less objective data on simulation skills retention. To investigate the retention of laparoscopic and robotic skills after simulation training. We present the second stage of a randomized single-blinded controlled trial in which 40 simulation-naïve medical students were randomly assigned to practice peg transfer tasks on either laparoscopic (N = 20, Fundamentals of Laparoscopic Surgery, Venture Technologies Inc., Waltham, MA) or robotic (N = 20, dV-Trainer, Mimic, Seattle, WA) platforms. In the first stage, two expert surgeons evaluated participants on both tasks before (Stage 1: Baseline) and immediately after training (Stage 1: Post-training) using a modified validated global rating scale of laparoscopic and robotic operative performance. In Stage 2, participants were evaluated on both tasks 11-20 weeks after training. Of the 40 students who participated in Stage 1, 23 (11 laparoscopic and 12 robotic) underwent repeat evaluation. During Stage 2, there were no significant differences between groups in objective or subjective measures for the laparoscopic task. Laparoscopic-trained participants' performances on the laparoscopic task were improved during Stage 2 compared to baseline measured by time to task completion, but not by the modified global rating scale. During the robotic task, the robotic-trained group demonstrated superior economy of motion (p = .017), Tissue Handling (p = .020), and fewer errors (p = .018) compared to the laparoscopic-trained group. Robotic skills acquisition from baseline with no significant deterioration as measured by modified global rating scale scores was observed among robotic-trained participants during Stage 2. Robotic skills acquired through simulation appear to be better maintained than laparoscopic simulation skills. This study is registered on ClinicalTrials.gov (NCT02370407).

[Effects of long-term mixed application of organic and inorganic fertilizers on canopy apparent photosynthesis and yield of winter wheat].

PubMed

Zhao, Jun; Dong, Shu-ting; Liu, Peng; Zhang, Ji-wang; Zhao, Bin

2015-08-01

A field experiment was conducted using the winter wheat (Triticum aestivum) variety Shimai 15. The source of organic nitrogen was cow manure, and four fertilization treatments were included, i.e., no N fertilizer application, single application of urea, single application of cow manure, and mixed application of urea and cow manure. The effects of different applications of inorganic and organic nitrogen on canopy apparent photosynthesis (CAP), photosynthetic rate of flag leaves (Pn), leaf area index (LAI), florescence parameters and grain yield of winter wheat were determined. The results showed that urea had the largest effect on the early growth period, as at this stage the CAP, Pn and LAI of the single application of urea were the highest, which was followed by the mixed application and the single application of cow manure. However, 10 days after anthesis, the single application of cow manure and the mixed application delayed the leaf senescence process when compared with the single application of urea. This could be due to the two treatments having higher anti-oxidant enzyme activity and promoting a longer green leaf duration, which could maintain a higher photosynthetic capability. What' s more, the mixed application had a better performance and got the highest grain yield. Consequently, the mixed application of organic and inorganic fertilizers could delay leaf senescence and maintain a better canopy structure and higher photosynthesis capability at the late grain filling stage, which resulted in a higher grain yield.

Single Marital Status and Infectious Mortality in Women With Cervical Cancer in the United States.

PubMed

Machida, Hiroko; Eckhardt, Sarah E; Castaneda, Antonio V; Blake, Erin A; Pham, Huyen Q; Roman, Lynda D; Matsuo, Koji

2017-10-01

Unmarried status including single marital status is associated with increased mortality in women bearing malignancy. Infectious disease weights a significant proportion of mortality in patients with malignancy. Here, we examined an association of single marital status and infectious mortality in cervical cancer. This is a retrospective observational study examining 86,555 women with invasive cervical cancer identified in the Surveillance, Epidemiology, and End Results Program between 1973 and 2013. Characteristics of 18,324 single women were compared with 38,713 married women in multivariable binary logistic regression models. Propensity score matching was performed to examine cumulative risk of all-cause and infectious mortality between the 2 groups. Single marital status was significantly associated with young age, black/Hispanic ethnicity, Western US residents, uninsured status, high-grade tumor, squamous histology, and advanced-stage disease on multivariable analysis (all, P < 0.05). In a prematched model, single marital status was significantly associated with increased cumulative risk of all-cause mortality (5-year rate: 32.9% vs 29.7%, P < 0.001) and infectious mortality (0.5% vs 0.3%, P < 0.001) compared with the married status. After propensity score matching, single marital status remained an independent prognostic factor for increased cumulative risk of all-cause mortality (adjusted hazards ratio [HR], 1.15; 95% confidence interval [CI], 1.11-1.20; P < 0.001) and those of infectious mortality on multivariable analysis (adjusted HR, 1.71; 95% CI, 1.27-2.32; P < 0.001). In a sensitivity analysis for stage I disease, single marital status remained significantly increased risk of infectious mortality after propensity score matching (adjusted HR, 2.24; 95% CI, 1.34-3.73; P = 0.002). Single marital status was associated with increased infectious mortality in women with invasive cervical cancer.

An Efficient Framework Model for Optimizing Routing Performance in VANETs

PubMed Central

Zulkarnain, Zuriati Ahmad; Subramaniam, Shamala

2018-01-01

Routing in Vehicular Ad hoc Networks (VANET) is a bit complicated because of the nature of the high dynamic mobility. The efficiency of routing protocol is influenced by a number of factors such as network density, bandwidth constraints, traffic load, and mobility patterns resulting in frequency changes in network topology. Therefore, Quality of Service (QoS) is strongly needed to enhance the capability of the routing protocol and improve the overall network performance. In this paper, we introduce a statistical framework model to address the problem of optimizing routing configuration parameters in Vehicle-to-Vehicle (V2V) communication. Our framework solution is based on the utilization of the network resources to further reflect the current state of the network and to balance the trade-off between frequent changes in network topology and the QoS requirements. It consists of three stages: simulation network stage used to execute different urban scenarios, the function stage used as a competitive approach to aggregate the weighted cost of the factors in a single value, and optimization stage used to evaluate the communication cost and to obtain the optimal configuration based on the competitive cost. The simulation results show significant performance improvement in terms of the Packet Delivery Ratio (PDR), Normalized Routing Load (NRL), Packet loss (PL), and End-to-End Delay (E2ED). PMID:29462884

Immediate Single-Stage Reconstruction of Complex Frontofaciobasal Injuries: Part I

PubMed Central

Awadalla, Akram Mohamed; Ezzeddine, Hichem; Fawzy, Naglaaa; Saeed, Mohammad Al; Ahmad, Mohammad R.

2014-01-01

Objective To determine if immediate (within 6 hours of adequate resuscitation) single-stage repair of complex craniofacial injuries could be accomplished with acceptable morbidity and mortality taking into consideration the cosmetic appearance of the patient. Patients and Methods A total of 26 patients (19 men, 7 women) ranging in age from 8 to 58 years with Glasgow Coma Scale scores of 5 to 15 all had a combined single-stage repair of their complex craniofacial injuries within 6 hours of their admission. After initial assessment and adequate resuscitation, they were evaluated with three-dimensional computed tomography of the face and head. Coronal skin flap was used for maximum exposure for frontal sinus exenteration as well as dural repair, cortical debridement, calvarial reconstruction, and titanium mesh placement. Results Neurosurgical outcome at both the early and late evaluations was judged as good in 22 of 26 patients (85%), moderate in 3 of 26 (11%), and poor in 1 of the 26 (3.8%). Cosmetic surgical outcome at the early evaluation showed 17 of 26 (65%) to be excellent, 4 of 26 (15.5%) to be good, 4 patients (15.5%) to be fair, and 1 patient (3.8%) to be poor. At the late reevaluation, the fair had improved to good with an additional reconstructive procedure, and the poor had improved to fair with another surgery. There was no calvarial osteomyelitis, graft resorption, or intracranial abscess. Complications included three patients (11%): one (3.8%) had tension pneumocephaly and meningitis, one (3.8%) had delayed cerebrospinal fluid leak with recurrent attacks of meningitis, and one had a maxillary sinus infection (3.8%) secondary to front maxillary fistula. Conclusion The immediate single-stage repair of complex craniofacial injuries can be performed with acceptable results, a decreased need for reoperation, and improved cosmetic and functional outcomes. PMID:25844296

Impedance-matched Marx generators

NASA Astrophysics Data System (ADS)

Stygar, W. A.; LeChien, K. R.; Mazarakis, M. G.; Savage, M. E.; Stoltzfus, B. S.; Austin, K. N.; Breden, E. W.; Cuneo, M. E.; Hutsel, B. T.; Lewis, S. A.; McKee, G. R.; Moore, J. K.; Mulville, T. D.; Muron, D. J.; Reisman, D. B.; Sceiford, M. E.; Wisher, M. L.

2017-04-01

We have conceived a new class of prime-power sources for pulsed-power accelerators: impedance-matched Marx generators (IMGs). The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with L C time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22 -Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19 -Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-power-output time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.

Slip and Twinning in the [ 1 ¯ $ /line{mathbf{1}} $ 49]-Oriented Single Crystals of a High-Entropy Alloy

NASA Astrophysics Data System (ADS)

Kireeva, I. V.; Chumlyakov, Yu. I.; Pobedennaya, Z. V.; Platonova, Yu. N.; Kuksgauzen, I. V.; Kuksgauzen, D. A.; Poklonov, V. V.; Karaman, I.; Sehitoglu, H.

2016-12-01

Using [ overline{1} 49] - oriented single crystals of an FCC Fe20Ni20Mn20Cr20Co20 (at.%) high-entropy alloy subjected to tensile deformation, the temperature dependence of critical resolved shear stresses τcr(T) and the deformation mechanism of slip and twinning are investigated in the early stages of deformation at ɛ ≤ 5% within the temperature interval T = 77-573 K. It is shown that τcr increases with decreasing the testing temperature and the τcr(T) temperature dependence is controlled by the slip of perfect dislocations a/2<110>. The early deformation stages ɛ ≤ 5% are associated with the development of planar slip by pileups of perfect dislocations a/2<110>, stacking faults and mechanical twins, which is observed in the temperature interval from 77 to 423 K. A comparison of the temperature dependence τcr(T) and the development of mechanical twinning is performed between the [ overline{1} 49] -oriented single crystals of the Fe20Ni20Mn20Cr20Co20 high-entropy alloy, the single crystals of the austenitic stainless steel, Fe - 18% Cr - 12% Ni - 2Mo (wt.%) without nitrogen atoms (Steel 316) and Hadfield steel, Fe - 13% Mn - (1-1.3)% C (wt.%).

Design options for advanced manned launch systems

NASA Astrophysics Data System (ADS)

Freeman, Delma C.; Talay, Theodore A.; Stanley, Douglas O.; Lepsch, Roger A.; Wilhite, Alan W.

1995-03-01

Various concepts for advanced manned launch systems are examined for delivery missions to space station and polar orbit. Included are single-and two-stage winged systems with rocket and/or air-breathing propulsion systems. For near-term technologies, two-stage reusable rocket systems are favored over single-stage rocket or two-stage air-breathing/rocket systems. Advanced technologies enable viable single-stage-to-orbit (SSTO) concepts. Although two-stage rocket systems continue to be lighter in dry weight than SSTO vehicles, advantages in simpler operations may make SSTO vehicles more cost-effective over the life cycle. Generally, rocket systems maintain a dry-weight advantage over air-breathing systems at the advanced technology levels, but to a lesser degree than when near-term technologies are used. More detailed understanding of vehicle systems and associated ground and flight operations requirements and procedures is essential in determining quantitative discrimination between these latter concepts.

Inlet Development for a Rocket Based Combined Cycle, Single Stage to Orbit Vehicle Using Computational Fluid Dynamics

NASA Technical Reports Server (NTRS)

DeBonis, J. R.; Trefny, C. J.; Steffen, C. J., Jr.

1999-01-01

Design and analysis of the inlet for a rocket based combined cycle engine is discussed. Computational fluid dynamics was used in both the design and subsequent analysis. Reynolds averaged Navier-Stokes simulations were performed using both perfect gas and real gas assumptions. An inlet design that operates over the required Mach number range from 0 to 12 was produced. Performance data for cycle analysis was post processed using a stream thrust averaging technique. A detailed performance database for cycle analysis is presented. The effect ot vehicle forebody compression on air capture is also examined.

Viscoelastic stability in a single-screw channel flow

NASA Astrophysics Data System (ADS)

Agbessi, Y.; Bu, L. X.; Béreaux, Y.; Charmeau, J.-Y.

2018-05-01

In this work, we perform a linear stability analysis on pressure and drag flows of an Upper Convected Maxwell viscoelastic fluid. We use the well-recognised method of expanding the disturbances in Chebyschev polynomials and solve the resulting generalized eigenvalues problem with a collocation spectra method. Both the level of elasticity and the back-pressure vary. In a second stage, recent analytic solutions of viscoelastic fluid flows in slowly varying sections [1] are used to extend this stability analysis to flows in a compression or in a diverging section of a single screw channel, for example a wave mixing screw.

Quantum-classical interface based on single flux quantum digital logic

NASA Astrophysics Data System (ADS)

McDermott, R.; Vavilov, M. G.; Plourde, B. L. T.; Wilhelm, F. K.; Liebermann, P. J.; Mukhanov, O. A.; Ohki, T. A.

2018-04-01

We describe an approach to the integrated control and measurement of a large-scale superconducting multiqubit array comprising up to 108 physical qubits using a proximal coprocessor based on the Single Flux Quantum (SFQ) digital logic family. Coherent control is realized by irradiating the qubits directly with classical bitstreams derived from optimal control theory. Qubit measurement is performed by a Josephson photon counter, which provides access to the classical result of projective quantum measurement at the millikelvin stage. We analyze the power budget and physical footprint of the SFQ coprocessor and discuss challenges and opportunities associated with this approach.

The XQC microcalorimeter sounding rocket: a stable LTD platform 30 seconds after rocket motor burnout

NASA Astrophysics Data System (ADS)

Porter, F. S.; Almy, R.; Apodaca, E.; Figueroa-Feliciano, E.; Galeazzi, M.; Kelley, R.; McCammon, D.; Stahle, C. K.; Szymkowiak, A. E.; Sanders, W. T.

2000-04-01

The XQC microcalorimeter sounding rocket experiment is designed to provide a stable thermal environment for an LTD detector system within 30 s of the burnout of its second stage rocket motor. The detector system used for this instrument is a 36-pixel microcalorimeter array operated at 60 mK with a single-stage adiabatic demagnetization refrigerator (ADR). The ADR is mounted on a space-pumped liquid helium tank with vapor cooled shields which is vibration isolated from the rocket structure. We present here some of the design and performance details of this mature LTD instrument, which has just completed its third suborbital flight.

Metric learning for automatic sleep stage classification.

PubMed

Phan, Huy; Do, Quan; Do, The-Luan; Vu, Duc-Lung

2013-01-01

We introduce in this paper a metric learning approach for automatic sleep stage classification based on single-channel EEG data. We show that learning a global metric from training data instead of using the default Euclidean metric, the k-nearest neighbor classification rule outperforms state-of-the-art methods on Sleep-EDF dataset with various classification settings. The overall accuracy for Awake/Sleep and 4-class classification setting are 98.32% and 94.49% respectively. Furthermore, the superior accuracy is achieved by performing classification on a low-dimensional feature space derived from time and frequency domains and without the need for artifact removal as a preprocessing step.

A new gun facility dedicated to performing shock physics and terminal ballistics experiments

NASA Astrophysics Data System (ADS)

Zakraysek, Alan J.; Sutherland, Gerrit T.; Sandusky, Harold D.; Strange, David

2000-04-01

A new building has been constructed to house various powder and single-stage and two-stage gas guns at the Naval Surface Warfare Center, Indian Head Division. Guns previously located at the Naval Research Laboratory and the former White Oak Site of the Naval Surface Warfare Center have been relocated here. Most of the guns are mounted on moveable pedestals to allow them to be shot into various chambers. The facility includes a concrete blast chamber, a target chamber/catch tank for flyer plate experiments, and a target chamber outfitted for terminal ballistics measurements. This paper will discuss the capabilities of this new facility.

Evaluation of Water Injection Effect on NO(x) Formation for a Staged Gas Turbine Combustor

NASA Technical Reports Server (NTRS)

Fan, L.; Yang, S. L.; Kundu, K. P.

1996-01-01

NO(x) emission control by water injection on a staged turbine combustor (STC) was modeled using the KIVA-2 code with modification. Water is injected into the rich-burn combustion zone of the combustor by a single nozzle. Parametric study for different water injection patterns was performed. Results show NO(x) emission will decrease after water being injected. Water nozzle location also has significant effect for NO formation and fuel ignition. The chemical kinetic model is also sensitive to the excess water. Through this study, a better understanding of the physics and chemical kinetics is obtained, this will enhance the STC design process.

Fatique crack growth behavior of a single crystal alloy as observed through an in situ fatigue loading stage

NASA Technical Reports Server (NTRS)

Telesman, Jack; Kantzos, Peter

1988-01-01

An in situ fatigue loading stage inside a scanning electron microscope (SEM) was used to determine the fatigue crack growth behavior of a PWA 1480 single-crystal nickel-based superalloy. The loading stage permits real-time viewing of the fatigue damage processes at high magnification. The PWA 1480 single-crystal, single-edge notch specimens were tested with the load axis parallel to the (100) orientation. Two distinct fatigue failure mechanisms were identified. The crack growth rate differed substantially when the failure occurred on a single slip system in comparison to multislip system failure. Two processes by which crack branching is produced were identified and are discussed. Also discussed are the observed crack closure mechanisms.

Systematic review and meta-analysis of feasibility, safety, and efficacy of a novel procedure: associating liver partition and portal vein ligation for staged hepatectomy.

PubMed

Schadde, Erik; Schnitzbauer, Andreas A; Tschuor, Christoph; Raptis, Dimitri A; Bechstein, Wolf O; Clavien, Pierre-Alain

2015-09-01

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a novel strategy to resect liver tumors despite the small size of the liver remnant. It is an hepatectomy in two stages, with PVL and parenchymal transection during the first stage, which induces rapid growth of the remnant liver exceeding any other technique. Despite high postoperative morbidity and mortality in most reports, the technique was adopted by a number of surgeons. This systematic review explores current data regarding the feasibility, safety, and oncologic efficacy of ALPPS; the search strategy has been published online. A meta-analysis of hypertrophy, feasibility (ALPPS stage 2 performed), mortality, complications, and R0 (complete) resection was performed. A literature search revealed a total of 13 publications that met the search criteria, reporting data from 295 patients. Evidence levels were low, with the highest Oxford evidence level being 2c. The most common indication was colorectal liver metastasis in 203 patients. Hypertrophy in the meta-analysis was 84 %, feasibility (ALPPS stage 2 performed) 97 % (CI 94-99 %), 90-day mortality 11 % (CI 8-16 %), and complications grade IIIa or higher occured in 44 % (CI 38-50 %) of patients. A standardized reporting format for complications is lacking despite the widespread use of the Clavien-Dindo classification. Oncological outcome is not well-documented. The most common topics in the selected studies published were technical feasibility and indications for the procedures. Publication bias due to case-series and single-center reports is common. A systematic exploration of this novel operation with a rigid methodology, such as registry analyses and a randomized controlled trial, is highly advised.

Earth-to-orbit reusable launch vehicles: A comparative assessment

NASA Technical Reports Server (NTRS)

Chase, R. L.

1978-01-01

A representative set of space systems, functions, and missions for NASA and DoD from which launch vehicle requirements and characteristics was established as well as a set of air-breathing launch vehicles based on graduated technology capabilities corresponding to increasingly higher staging Mach numbers. The utility of the air-breathing launch vehicle candidates based on lift-off weight, performance, technology needs, and risk was assessed and costs were compared to alternative concepts. The results indicate that a fully reusable launch vehicle, whether two stage or one stage, could potentially reduce the cost per flight 60-80% compared to that for a partially reusable vehicle but would require advances in thermal protection system technology. A two-stage-to-orbit, parallel-lift vehicle with an air-breathing booster would cost approximately the same as a single-stage-to-orbit vehicle, but the former would have greater flexibility and a significantly reduced developmental risk. A twin-booster, subsonic-staged, parallel-lift vehicle represents the lowest system cost and developmental risk. However, if a large supersonic turbojet engine in the 350,000-N thrust class were available, supersonic staging would be preferred, and the investment in development would be returned in reduced program cost.

Relative Value of Restaging MRI, CT, and FDG-PET Scan After Preoperative Chemoradiation for Rectal Cancer.

PubMed

Schneider, Daniel A; Akhurst, Timothy J; Ngan, Samuel Y; Warrier, Satish K; Michael, Michael; Lynch, Andrew C; Te Marvelde, Luc; Heriot, Alexander G

2016-03-01

Management of rectal cancer has become multidisciplinary and is driven by the stage of the disease, with increased focus on restaging rectal cancer after neoadjuvant therapy. The purpose of this study was to assess the relative impact of restaging after preoperative chemoradiation with FDG-PET scan, CT, and MRI in the management of patients with rectal cancer. This was a retrospective study from a single institution. This study was conducted at a tertiary cancer center. A total of 199 patients met the inclusion criteria: patients with rectal adenocarcinoma; staged with positron emission tomography, CT, and MRI; T2 to T4, N0 to N2, M0 to M1; treated with neoadjuvant chemoradiation 50.4 Gy and infusional 5-fluorouracil; and restaged 4 weeks after chemoradiation before surgery between 2003 and 2013. Comparisons of the tumor stage among different imaging modalities before and after neoadjuvant chemoradiation were performed. The impact of restaging on the management plan was assessed. The stage at presentation was T2, 8.04%; T3, 65.33%; T4, 26.63%; N0, 17.09%; N1, 47.74%; N2, 34.67%; M0, 81.91%; and M1, 18.09%. Changes in disease stage postneoadjuvant chemoradiation were observed in 99 patients (50%). The management plans of 29 patients (15%) were changed. The impact of each restaging modality on management for all of the patients was positron emission tomography, 11%; CT, 4%; and MRI, 4%. In patients with metastatic disease at primary staging, the relative impact of each restaging modality in changing management was positron emission tomography, 32%; CT, 18%; and MRI, 6%. This study was limited by its single-center and retrospective design. Operations were performed 4 weeks after restaging. Changes in the extent of disease after long-course chemoradiotherapy result in changes of management in a significant percentage of patients. Positron emission tomography has the most significant impact in the change of management overall, and its use in restaging advanced rectal cancer should be further explored.

Multicohort Genomewide Association Study Reveals a New Signal of Protection Against HIV-1 Acquisition

PubMed Central

Limou, Sophie; Delaneau, Olivier; van Manen, Daniëlle; An, Ping; Sezgin, Efe; Le Clerc, Sigrid; Coulonges, Cédric; Troyer, Jennifer L.; Veldink, Jan H.; van den Berg, Leonard H.; Spadoni, Jean-Louis; Taing, Lieng; Labib, Taoufik; Montes, Matthieu; Delfraissy, Jean-François; Schachter, François; O’Brien, Stephen J.; Buchbinder, Susan; van Natta, Mark L.; Jabs, Douglas A.; Froguel, Philippe; Schuitemaker, Hanneke; Winkler, Cheryl A.

2012-01-01

Background. To date, only mutations in CCR5 have been shown to confer resistance to human immunodeficiency virus type 1 (HIV-1) infection, and these explain only a small fraction of the observed variability in HIV susceptibility. Methods. We performed a meta-analysis between 2 independent European genomewide association studies, each comparing HIV-1 seropositive cases with normal population controls known to be HIV uninfected, to identify single-nucleotide polymorphisms (SNPs) associated with the HIV-1 acquisition phenotype. SNPs exhibiting P < 10−5 in this first stage underwent second-stage analysis in 2 independent US cohorts of European descent. Results. After the first stage, a single highly significant association was revealed for the chromosome 8 rs6996198 with HIV-1 acquisition and was replicated in both second-stage cohorts. Across the 4 groups, the rs6996198-T allele was consistently associated with a significant reduced risk of HIV-1 infection, and the global meta-analysis reached genomewide significance: Pcombined = 7.76 × 10−8. Conclusions. We provide strong evidence of association for a common variant with HIV-1 acquisition in populations of European ancestry. This protective signal against HIV-1 infection is the first identified outside the CCR5 nexus. First clues point to a potential functional role for a nearby candidate gene, CYP7B1, but this locus warrants further investigation. PMID:22362864

Experimental analysis of the aerodynamic performance of an innovative low pressure turbine rotor

NASA Astrophysics Data System (ADS)

Infantino, Daniele; Satta, Francesca; Simoni, Daniele; Ubaldi, Marina; Zunino, Pietro; Bertini, Francesco

2016-02-01

In the present work the aerodynamic performances of an innovative rotor blade row have been experimentally investigated. Measurements have been carried out in a large scale low speed single stage cold flow facility at a Reynolds number typical of aeroengine cruise, under nominal and off-design conditions. The time-mean blade aerodynamic loadings have been measured at three radial positions along the blade height through a pressure transducer installed inside the hollow shaft, by delivering the signal to the stationary frame with a slip ring. The time mean aerodynamic flow fields upstream and downstream of the rotor have been measured by means of a five-hole probe to investigate the losses associated with the rotor. The investigations in the single stage research turbine allow the reproduction of both wake-boundary layer interaction as well as vortex-vortex interaction. The detail of the present results clearly highlights the strong dissipative effects induced by the blade tip vortex and by the momentum defect as well as the turbulence production, which is generated during the migration of the stator wake in the rotor passage. Phase-locked hot-wire investigations have been also performed to analyze the time-varying flow during the wake passing period. In particular the interaction between stator and rotor structures has been investigated also under off-design conditions to further explain the mechanisms contributing to the loss generation for the different conditions.

Applications of the Magnetocaloric Effect in Single-Stage, Multi-Stage and Continuous Adiabatic Demagnetization Refrigerators

NASA Technical Reports Server (NTRS)

Shirron, Peter J.

2014-01-01

Adiabatic demagnetization refrigerators (ADR), based on the magnetocaloric effect, are solid-state coolers that were the first to achieve cooling well into the sub-kelvin regime. Although supplanted by more powerful dilution refrigerators in the 1960s, ADRs have experienced a revival due to the needs of the space community for cooling astronomical instruments and detectors to temperatures below 100 mK. The earliest of these were single-stage refrigerators using superfluid helium as a heat sink. Their modest cooling power (<1 µW at 60 mK[1]) was sufficient for the small (6x6) detector arrays[2], but recent advances in arraying and multiplexing technologies[3] are generating a need for higher cooling power (5-10 µW), and lower temperature (<30 mK). Single-stage ADRs have both practical and fundamental limits to their operating range, as mass grows very rapidly as the operating range is expanded. This has led to the development of new architectures that introduce multi-staging as a way to improve operating range, efficiency and cooling power. Multi-staging also enables ADRs to be configured for continuous operation, which greatly improves cooling power per unit mass. This paper reviews the current field of adiabatic demagnetization refrigeration, beginning with a description of the magnetocaloric effect and its application in single-stage systems, and then describing the challenges and capabilities of multi-stage and continuous ADRs.

Meta-Analysis in Genome-Wide Association Datasets: Strategies and Application in Parkinson Disease

PubMed Central

Evangelou, Evangelos; Maraganore, Demetrius M.; Ioannidis, John P.A.

2007-01-01

Background Genome-wide association studies hold substantial promise for identifying common genetic variants that regulate susceptibility to complex diseases. However, for the detection of small genetic effects, single studies may be underpowered. Power may be improved by combining genome-wide datasets with meta-analytic techniques. Methodology/Principal Findings Both single and two-stage genome-wide data may be combined and there are several possible strategies. In the two-stage framework, we considered the options of (1) enhancement of replication data and (2) enhancement of first-stage data, and then, we also considered (3) joint meta-analyses including all first-stage and second-stage data. These strategies were examined empirically using data from two genome-wide association studies (three datasets) on Parkinson disease. In the three strategies, we derived 12, 5, and 49 single nucleotide polymorphisms that show significant associations at conventional levels of statistical significance. None of these remained significant after conservative adjustment for the number of performed analyses in each strategy. However, some may warrant further consideration: 6 SNPs were identified with at least 2 of the 3 strategies and 3 SNPs [rs1000291 on chromosome 3, rs2241743 on chromosome 4 and rs3018626 on chromosome 11] were identified with all 3 strategies and had no or minimal between-dataset heterogeneity (I2 = 0, 0 and 15%, respectively). Analyses were primarily limited by the suboptimal overlap of tested polymorphisms across different datasets (e.g., only 31,192 shared polymorphisms between the two tier 1 datasets). Conclusions/Significance Meta-analysis may be used to improve the power and examine the between-dataset heterogeneity of genome-wide association studies. Prospective designs may be most efficient, if they try to maximize the overlap of genotyping platforms and anticipate the combination of data across many genome-wide association studies. PMID:17332845

Quantifying gait patterns in Parkinson's disease

NASA Astrophysics Data System (ADS)

Romero, Mónica; Atehortúa, Angélica; Romero, Eduardo

2017-11-01

Parkinson's disease (PD) is constituted by a set of motor symptoms, namely tremor, rigidity, and bradykinesia, which are usually described but not quantified. This work proposes an objective characterization of PD gait patterns by approximating the single stance phase a single grounded pendulum. This model estimates the force generated by the gait during the single support from gait data. This force describes the motion pattern for different stages of the disease. The model was validated using recorded videos of 8 young control subjects, 10 old control subjects and 10 subjects with Parkinson's disease in different stages. The estimated force showed differences among stages of Parkinson disease, observing a decrease of the estimated force for the advanced stages of this illness.

Multi-stage responsive 4D printed smart structure through varying geometric thickness of shape memory polymer

NASA Astrophysics Data System (ADS)

Teoh, Joanne Ee Mei; Zhao, Yue; An, Jia; Chua, Chee Kai; Liu, Yong

2017-12-01

Shape memory polymers (SMPs) have gained a presence in additive manufacturing due to their role in 4D printing. They can be printed either in multi-materials for multi-stage shape recovery or in a single material for single-stage shape recovery. When printed in multi-materials, material or material-based design is used as a controlling factor for multi-stage shape recovery. However, when printed in a single material, it is difficult to design multi-stage shape recovery due to the lack of a controlling factor. In this research, we explore the use of geometric thickness as a controlling factor to design smart structures possessing multi-stage shape recovery using a single SMP. L-shaped hinges with a thickness ranging from 0.3-2 mm were designed and printed in four different SMPs. The effect of thickness on SMP’s response time was examined via both experiment and finite element analysis using Ansys transient thermal simulation. A method was developed to accurately measure the response time in millisecond resolution. Temperature distribution and heat transfer in specimens during thermal activation were also simulated and discussed. Finally, a spiral square and an artificial flower consisting of a single SMP were designed and printed with appropriate thickness variation for the demonstration of a controlled multi-stage shape recovery. Experimental results indicated that smart structures printed using single material with controlled thickness parameters are able to achieve controlled shape recovery characteristics similar to those printed with multiple materials and uniform geometric thickness. Hence, the geometric parameter can be used to increase the degree of freedom in designing future smart structures possessing complex shape recovery characteristics.

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

PubMed

Demissie, Serkalem; Cupples, L Adrienne

2011-11-01

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

One-Stage Cleft Lip and Palate Repair in an Older Population.

PubMed

Guneren, Ethem; Canter, Halil Ibrahim; Yildiz, Kemalettin; Kayan, Resit Burak; Ozpur, Mustafa Aykut; Baygol, Emre Gonenc; Sagir, Haci Omer; Kuzu, Ismail Melih; Akman, Onur; Arslan, Serap

2015-07-01

In underdeveloped countries one-stage definitive repair of cleft lip and palate is considered for late-presenting patients. A total of 25 patients with unoperated cleft lip and palate more than 2 years of age were enrolled in this study for one-stage simultaneous repair of cleft lip and palate. According to Veau-Wardill-Kilner push-back technique, 2 flap palatoplasties were performed for palatal repairs; all of the lips were repaired with the Millard II rotation-advancement technique. The authors experienced no perioperative or postoperative life-threatening complications. With respect to the registered operation periods, longer times were required to perform these double operations, but this elongation is shorter than the sum of the periods if the 2 operations had been performed separately. Although the authors were unable to evaluate the late postoperative results because the authors could not follow-up the patients after they were discharged the day after surgery, the early results related to the success of the operation without any surgical complication were prone to meet the parents' and patients' expectations. The authors presented their experiences with many volunteer cleft lip and palate trips to third world countries; however the structure of this article is not a new hypothesis and data based to support a scientific study, but observations are objective to get a conclusion. To perform one-stage definitive repair of the cleft lip and palate in late-presented patients was the reality that they had only 1 chance to undergo these operations. According to the terms and conditions of this challenging operation, one-stage simultaneous repair of cleft lip and palate is a more demanding and time-consuming procedure than is isolated cleft lip repair or cleft palate repair. Although technically challenging, single-stage repair of the whole deformity in late-presenting patients is a feasible, reliable, successful, and safe procedure in authors' experience.

Using public control genotype data to increase power and decrease cost of case-control genetic association studies.

PubMed

Ho, Lindsey A; Lange, Ethan M

2010-12-01

Genome-wide association (GWA) studies are a powerful approach for identifying novel genetic risk factors associated with human disease. A GWA study typically requires the inclusion of thousands of samples to have sufficient statistical power to detect single nucleotide polymorphisms that are associated with only modest increases in risk of disease given the heavy burden of a multiple test correction that is necessary to maintain valid statistical tests. Low statistical power and the high financial cost of performing a GWA study remains prohibitive for many scientific investigators anxious to perform such a study using their own samples. A number of remedies have been suggested to increase statistical power and decrease cost, including the utilization of free publicly available genotype data and multi-stage genotyping designs. Herein, we compare the statistical power and relative costs of alternative association study designs that use cases and screened controls to study designs that are based only on, or additionally include, free public control genotype data. We describe a novel replication-based two-stage study design, which uses free public control genotype data in the first stage and follow-up genotype data on case-matched controls in the second stage that preserves many of the advantages inherent when using only an epidemiologically matched set of controls. Specifically, we show that our proposed two-stage design can substantially increase statistical power and decrease cost of performing a GWA study while controlling the type-I error rate that can be inflated when using public controls due to differences in ancestry and batch genotype effects.

A Study of the Effects of School Size and Single-Sex Education in English Schools

ERIC Educational Resources Information Center

Spielhofer, Thomas; Benton, Tom; Schagen, Sandie

2004-01-01

National value-added datasets have recently become available that record a pupil's progress from Key Stage 2 right through to GCSE. Such a dataset is clearly a useful tool for assessing the impact various characteristics of secondary schools have on pupil performance. This paper reports on a research project which involved the use of a variety of…

High-gain EDFA using ASE suppression: numerical simulation and experimental characterization

NASA Astrophysics Data System (ADS)

Woellner, Eudes F.; Fugihara, Meire C.; Vendramin, Marcio; Chitz, Edson; Kalinowski, Hypolito J.; Pontes, Maria J.

2001-08-01

A single stage, bi-directionally pumped Erbium Doped Fiber Amplifier is studied, using a scheme that reduces the counter propagating ASE, avoiding self saturation due to ASE. The amplifier is numerically simulated and experimentally characterized. Gain, saturation and polarization dependence measurements are carried to compare with simulated results. Transient response is simulated to verify the amplifier performance in cable television distribution network.

Comparison of two-stage thermophilic (68 degrees C/55 degrees C) anaerobic digestion with one-stage thermophilic (55 degrees C) digestion of cattle manure.

PubMed

Nielsen, H B; Mladenovska, Z; Westermann, P; Ahring, B K

2004-05-05

A two-stage 68 degrees C/55 degrees C anaerobic degradation process for treatment of cattle manure was studied. In batch experiments, an increase of the specific methane yield, ranging from 24% to 56%, was obtained when cattle manure and its fractions (fibers and liquid) were pretreated at 68 degrees C for periods of 36, 108, and 168 h, and subsequently digested at 55 degrees C. In a lab-scale experiment, the performance of a two-stage reactor system, consisting of a digester operating at 68 degrees C with a hydraulic retention time (HRT) of 3 days, connected to a 55 degrees C reactor with 12-day HRT, was compared with a conventional single-stage reactor running at 55 degrees C with 15-days HRT. When an organic loading of 3 g volatile solids (VS) per liter per day was applied, the two-stage setup had a 6% to 8% higher specific methane yield and a 9% more effective VS-removal than the conventional single-stage reactor. The 68 degrees C reactor generated 7% to 9% of the total amount of methane of the two-stage system and maintained a volatile fatty acids (VFA) concentration of 4.0 to 4.4 g acetate per liter. Population size and activity of aceticlastic methanogens, syntrophic bacteria, and hydrolytic/fermentative bacteria were significantly lower in the 68 degrees C reactor than in the 55 degrees C reactors. The density levels of methanogens utilizing H2/CO2 or formate were, however, in the same range for all reactors, although the degradation of these substrates was significantly lower in the 68 degrees C reactor than in the 55 degrees C reactors. Temporal temperature gradient electrophoresis profiles (TTGE) of the 68 degrees C reactor demonstrated a stable bacterial community along with a less divergent community of archaeal species. Copyright 2004 Wiley Periodicals, Inc.

Extra-Zodiacal-Cloud Astronomy via Solar Electric Propulsion

NASA Technical Reports Server (NTRS)

Benson, Scott W.; Falck, Robert D.; Oleson, Steven R.; Greenhouse, Matthew A.; Kruk, Jeffrey W.; Gardner, Jonathan P.; Thronson, Harley A.; Vaughn, Frank J.; Fixsen, Dale J.

2011-01-01

Solar electric propulsion (SEP) is often considered as primary propulsion for robotic planetary missions, providing the opportunity to deliver more payload mass to difficult, high-delta-velocity destinations. However, SEP application to astrophysics has not been well studied. This research identifies and assesses a new application of SEP as primary propulsion for low-cost high-performance robotic astrophysics missions. The performance of an optical/infrared space observatory in Earth orbit or at the Sun-Earth L2 point (SEL2) is limited by background emission from the Zodiacal dust cloud that has a disk morphology along the ecliptic plane. By delivering an observatory to a inclined heliocentric orbit, most of this background emission can be avoided, resulting in a very substantial increase in science performance. This advantage enabled by SEP allows a small-aperture telescope to rival the performance of much larger telescopes located at SEL2. In this paper, we describe a novel mission architecture in which SEP technology is used to enable unprecedented telescope sensitivity performance per unit collecting area. This extra-zodiacal mission architecture will enable a new class of high-performance, short-development time, Explorer missions whose sensitivity and survey speed can rival flagship-class SEL2 facilities, thus providing new programmatic flexibility for NASA's astronomy mission portfolio. A mission concept study was conducted to evaluate this application of SEP. Trajectory analyses determined that a 700 kg-class science payload could be delivered in just over 2 years to a 2 AU mission orbit inclined 15 to the ecliptic using a 13 kW-class NASA's Evolutionary Xenon Thruster (NEXT) SEP system. A mission architecture trade resulted in a SEP stage architecture, in which the science spacecraft separates from the stage after delivery to the mission orbit. The SEP stage and science spacecraft concepts were defined in collaborative engineering environment studies. The SEP stage architecture approach offers benefits beyond a single astrophysics mission. A variety of low-cost astrophysics missions could employ a standard SEP stage to achieve substantial science benefit. This paper describes the results of this study in detail, including trajectory analysis, spacecraft concept definition, description of telescope/instrument benefits, and application of the resulting SEP stage to other missions. In addition, the benefits of cooperative development and use of the SEP stage, in conjunction with a SEP flight demonstration mission currently in definition at NASA, are considered.

Single Incision Laparoscopic Surgery in Treating Patients With Colorectal Disease

ClinicalTrials.gov

2017-12-04

Adenomatous Polyp; Crohn Disease; Familial Adenomatous Polyposis; Hereditary Intestinal Polyposis Syndrome; Recurrent Colon Cancer; Stage I Colon Cancer; Stage IIA Colon Cancer; Stage IIB Colon Cancer; Stage IIC Colon Cancer; Stage IIIA Colon Cancer; Stage IIIB Colon Cancer; Stage IIIC Colon Cancer

Development of an efficient anaerobic co-digestion process for garbage, excreta, and septic tank sludge to create a resource recycling-oriented society.

PubMed

Sun, Zhao-Yong; Liu, Kai; Tan, Li; Tang, Yue-Qin; Kida, Kenji

2017-03-01

In order to develop a resource recycling-oriented society, an efficient anaerobic co-digestion process for garbage, excreta and septic tank sludge was studied based on the quantity of each biomass waste type discharged in Ooki machi, Japan. The anaerobic digestion characteristics of garbage, excreta and 5-fold condensed septic tank sludge (hereafter called condensed sludge) were determined separately. In single-stage mesophilic digestion, the excreta with lower C/N ratios yielded lower biogas volumes and accumulated higher volumes of volatile fatty acid (VFA). On the other hand, garbage allowed for a significantly larger volatile total solid (VTS) digestion efficiency as well as biogas yield by thermophilic digestion. Thus, a two-stage anaerobic co-digestion process consisting of thermophilic liquefaction and mesophilic digestion phases was proposed. In the thermophilic liquefaction of mixed condensed sludge and household garbage (wet mass ratio of 2.2:1), a maximum VTS loading rate of 24g/L/d was achieved. In the mesophilic digestion of mixed liquefied material and excreta (wet mass ratio of 1:1), biogas yield reached approximately 570ml/g-VTS fed with a methane content of 55% at a VTS loading rate of 1.0g/L/d. The performance of the two-stage process was evaluated by comparing it with a single-stage process in which biomass wastes were treated separately. Biogas production by the two-stage process was found to increase by approximately 22.9%. These results demonstrate the effectiveness of a two-stage anaerobic co-digestion process in enhancement of biogas production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Performance of CT scan of abdomen and pelvis in detecting asymptomatic synchronous metastasis in breast cancer.

PubMed

James, Justin; Teo, Melanie; Ramachandran, Vivekananda; Law, Michael; Stoney, David; Cheng, Michael

2017-10-01

In many centres in Australia, CT scan of abdomen and pelvis (CTAP) is a commonly used staging investigation to detect asymptomatic synchronous metastasis (ASM) in newly diagnosed breast cancer. However, its routine use is not supported by strong evidence either on its cost effectiveness or on specificity. Despite contrary recommendations by international guidelines this staging investigation is widely used among new early breast cancers(EBC). This retrospective study aims to assess the cost effectiveness and usefulness of CTAP in new breast cancers. All patients with primary invasive breast cancers who underwent breast cancer treatment through Eastern health breast unit during 50-month period from January 2012 were included in the study. All staging CTAP results were reviewed to evaluate its yield, false positive rate and cost of investigation per single positive result. Odds ratio for positive test results were calculated for five possible risk factors (Age less than 40 years, stage III disease, presence of LVI, HER2 positive disease and presence of metastasis in lymph node). 49% (n = 285) of all breast cancer patient underwent staging CTAP which lead to the detection of 4 ASM. (Over all yield of 1%) Overall false positive rate was 15% because of 42 indeterminate results needing further tests. Based merely on approved billing rates this amounted to $ 40733 per single ASM identified. Presence of lymph node metastasis did not increase the chance of positive test result (OR = 1.3; CI:0.13-12.69). Staging CTAP is associated with high incidence of false positive rates and low yield, especially among EBCs. It is desirable to choose this investigation more selectively than currently practiced. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Assessing the Validity of a Single-Item HIV Risk Stage-of-Change Measure

ERIC Educational Resources Information Center

Napper, Lucy E.; Branson, Catherine M.; Fisher, Dennis G.; Reynolds, Grace L.; Wood, Michelle M.

2008-01-01

This study examined the validity of a single-item measure of HIV risk stage of change that HIV prevention contractors were required to collect by the California State Office of AIDS. The single-item measure was compared to the more conventional University of Rhode Island Change Assessment (URICA). Participants were members of Los Angeles…

Clinical and Cost Implications of Universal Versus Locally Advanced-Stage and Advanced-Stage-Only Molecular Testing for Epidermal Growth Factor Receptor Mutations and Anaplastic Lymphoma Kinase Rearrangements in Non-Small Cell Lung Carcinoma: A Tertiary Academic Institution Experience.

PubMed

Sauter, Jennifer L; Butnor, Kelly J

2016-04-01

Although epidermal growth factor receptor (EGFR)- and anaplastic lymphoma kinase (ALK)-directed therapies are not approved for patients with early-stage non-small cell lung carcinoma (NSCLC), many institutions perform EGFR and ALK testing for all patients with NSCLC at the time of initial diagnosis. Current consensus guidelines recommend EGFR testing and suggest ALK testing at the time of initial diagnosis for patients with advanced disease. To examine the cost and clinical impact of EGFR and ALK testing of patients with early-stage NSCLC. Records from all patients with a diagnosis of NSCLC made on a nonresection specimen at our institution during a single calendar year (2012) were reviewed, and a cost analysis was performed. Of 133 total patients, 47 (35%) had early-stage (stage I or II) disease and 86 (65%) had locally advanced (stage III) or advanced (stage IV) disease at presentation. Eight of 47 patients with early-stage disease (17%) had progression/recurrence during 18 to 30 months of follow-up, 6 of 8 (75%) of whom had pathologic confirmation of progression/recurrence. The estimated additional cost of EGFR and ALK testing for all newly diagnosed patients with NSCLC at our institution is $75,200 per year, compared to testing only patients with locally advanced and advanced-stage disease. The cost of universal molecular testing of NSCLC is substantial. EGFR and ALK testing of patients with early-stage disease appears to have negligible clinical impact, as most patients do not have disease recurrence/progression. Those whose disease recurs/progresses typically undergo rebiopsy. Our findings do not support the practice of universal EGFR and ALK testing in NSCLC at the time of initial diagnosis.

Lengthening Temporalis Myoplasty for Single-Stage Smile Reconstruction in Children with Facial Paralysis.

PubMed

Panossian, Andre

2016-04-01

Free muscle transfer for dynamic smile reanimation in facial paralysis is not always predictable with regard to cosmesis. Hospital stays range from 5 to 7 days. Prolonged operative times, longer hospital stays, and excessive cheek bulk are associated with free flap options. Lengthening temporalis myoplasty offers single-stage smile reanimation with theoretical advantages over free tissue transfer. From 2012 to 2014, 18 lengthening temporalis myoplasties were performed in 14 children for smile reconstruction. A retrospective chart review was completed for demographics, operative times, length of hospital stay, and perioperative complications. Fourteen consecutive patients with complete facial paralysis were included. Four patients underwent single-stage bilateral reconstruction, and 10 underwent unilateral procedures. Diagnoses included Möbius syndrome (n = 5), posterior cranial fossa tumors (n = 4), posttraumatic (n = 2), hemifacial microsomia (n = 1), and idiopathic (n = 2). Average patient age was 10.1 years. Average operative time was 410 minutes (499 minutes for bilateral lengthening temporalis myoplasty and 373 for unilateral lengthening temporalis myoplasty). Average length of stay was 3.3 days (4.75 days for bilateral lengthening temporalis myoplasty and 2.8 for unilateral lengthening temporalis myoplasty). Nine patients required minor revisions. Lengthening temporalis myoplasty is a safe alternative to free tissue transfer for dynamic smile reconstruction in children with facial paralysis. Limited donor-site morbidity, shorter operative times, and shorter hospital stays are some benefits over free flap options. However, revisions are required frequently secondary to tendon avulsions and adhesions. Therapeutic, IV.

Effects of sludge recirculation rate and mixing time on performance of a prototype single-stage anaerobic digester for conversion of food wastes to biogas and energy recovery.

PubMed

Ratanatamskul, Chavalit; Saleart, Tawinan

2016-04-01

Food wastes have been recognized as the largest waste stream and accounts for 39.25 % of total municipal solid waste in Thailand. Chulalongkorn University has participated in the program of in situ energy recovery from food wastes under the Ministry of Energy (MOE), Thailand. This research aims to develop a prototype single-stage anaerobic digestion system for biogas production and energy recovery from food wastes inside Chulalongkorn University. Here, the effects of sludge recirculation rate and mixing time were investigated as the main key parameters for the system design and operation. From the results obtained in this study, it was found that the sludge recirculation rate of 100 % and the mixing time of 60 min per day were the most suitable design parameters to achieve high efficiencies in terms of chemical oxygen demand (COD), total solids (TS), and total volatile solid (TVS) removal and also biogas production by this prototype anaerobic digester. The obtained biogas production was found to be 0.71 m(3)/kg COD and the composition of methane was 61.6 %. Moreover, the efficiencies of COD removal were as high as 82.9 % and TVS removal could reach 83.9 % at the optimal condition. Therefore, the developed prototype single-stage anaerobic digester can be highly promising for university canteen application to recover energy from food wastes via biogas production.

An analytical method of estimating turbine performance

NASA Technical Reports Server (NTRS)

Kochendorfer, Fred D; Nettles, J Cary

1949-01-01

A method is developed by which the performance of a turbine over a range of operating conditions can be analytically estimated from the blade angles and flow areas. In order to use the method, certain coefficients that determine the weight flow and the friction losses must be approximated. The method is used to calculate the performance of the single-stage turbine of a commercial aircraft gas-turbine engine and the calculated performance is compared with the performance indicated by experimental data. For the turbine of the typical example, the assumed pressure losses and the tuning angles give a calculated performance that represents the trends of the experimental performance with reasonable accuracy. The exact agreement between analytical performance and experimental performance is contingent upon the proper selection of a blading-loss parameter.

Single-stage-to-orbit versus two-stage-two-orbit: A cost perspective

NASA Astrophysics Data System (ADS)

Hamaker, Joseph W.

1996-03-01

This paper considers the possible life-cycle costs of single-stage-to-orbit (SSTO) and two-stage-to-orbit (TSTO) reusable launch vehicles (RLV's). The analysis parametrically addresses the issue such that the preferred economic choice comes down to the relative complexity of the TSTO compared to the SSTO. The analysis defines the boundary complexity conditions at which the two configurations have equal life-cycle costs, and finally, makes a case for the economic preference of SSTO over TSTO.

Waterhammer Testing and Modeling of the Ares I Upper Stage Reaction Control System

NASA Technical Reports Server (NTRS)

Williams, J. Hunter; Holt, Kimberly A.

2010-01-01

NASA's Ares I rocket is the agency's first step in completing the goals of the Constellation Program, which plans to deliver a new generation of space explorers into low earth orbit for future missions to the International Space Station, the moon, and other destinations within the solar system. Ares I is a two-stage rocket topped by the Orion crew capsule and its service module. The launch vehicle's First Stage is a single, five-segment reusable solid rocket booster (RSRB), derived from the Space Shuttle Program's four segment RSRB. The vehicle's Upper Stage, being designed at Marshall Space Flight Center (MSFC), is propelled by a single J-2X Main Engine fueled with liquid oxygen and liquid hydrogen. During active Upper Stage flight of the Ares I launch vehicle, the Upper Stage Reaction Control System (US ReCS) will perform attitude control operations for the vehicle. The US ReCS will provide three-axis attitude control capability (roll, pitch, and yaw) for the Upper Stage while the J-2X is not firing and roll control capability while the engine is firing. Because of the requirements imposed upon the system, the design must accommodate rapid pulsing of multiple thrusters simultaneously to maintain attitude control. In support of these design activities and in preparation for Critical Design Review, analytical models of the US ReCS propellant feed system have been developed using the Thermal Hydraulic Library of MSC.EASY5 v.2008, herein referred to as EASY5. EASY5 is a commercially available fluid system modeling package with significant history of modeling space propulsion systems. In Fall 2009, a series of development tests were conducted at MSFC on a cold-flow test article for the US ReCS, herein referred to as System Development Test Article (SDTA). A subset of those tests performed were aimed at examining the effects of waterhammer on a flight-representative system and to ensure that those effects could be quantified with analytical models and incorporated into the design of the flight system. This paper presents an overview of the test article and the test approach, along with a discussion of the analytical modeling methodology. In addition, the results of that subset of development tests, along with analytical model pre-test predictions and post-test model correlations, will also be discussed in detail.

Eye of the Beholder: Stage Entrance Behavior and Facial Expression Affect Continuous Quality Ratings in Music Performance

PubMed Central

Waddell, George; Williamon, Aaron

2017-01-01

Judgments of music performance quality are commonly employed in music practice, education, and research. However, previous studies have demonstrated the limited reliability of such judgments, and there is now evidence that extraneous visual, social, and other “non-musical” features can unduly influence them. The present study employed continuous measurement techniques to examine how the process of forming a music quality judgment is affected by the manipulation of temporally specific visual cues. Video footage comprising an appropriate stage entrance and error-free performance served as the standard condition (Video 1). This footage was manipulated to provide four additional conditions, each identical save for a single variation: an inappropriate stage entrance (Video 2); the presence of an aural performance error midway through the piece (Video 3); the same error accompanied by a negative facial reaction by the performer (Video 4); the facial reaction with no corresponding aural error (Video 5). The participants were 53 musicians and 52 non-musicians (N = 105) who individually assessed the performance quality of one of the five randomly assigned videos via a digital continuous measurement interface and headphones. The results showed that participants viewing the “inappropriate” stage entrance made judgments significantly more quickly than those viewing the “appropriate” entrance, and while the poor entrance caused significantly lower initial scores among those with musical training, the effect did not persist long into the performance. The aural error caused an immediate drop in quality judgments that persisted to a lower final score only when accompanied by the frustrated facial expression from the pianist; the performance error alone caused a temporary drop only in the musicians' ratings, and the negative facial reaction alone caused no reaction regardless of participants' musical experience. These findings demonstrate the importance of visual information in forming evaluative and aesthetic judgments in musical contexts and highlight how visual cues dynamically influence those judgments over time. PMID:28487662

Comparing SiGe HBT Amplifier Circuits for Fast Single-shot Spin Readout

NASA Astrophysics Data System (ADS)

England, Troy; Curry, Matthew; Carr, Stephen; Mounce, Andrew; Jock, Ryan; Sharma, Peter; Bureau-Oxton, Chloe; Rudolph, Martin; Hardin, Terry; Carroll, Malcolm

Fast, low-power quantum state readout is one of many challenges facing quantum information processing. Single electron transistors (SETs) are potentially fast, sensitive detectors for performing spin readout. From a circuit perspective, however, their output impedance and nonlinear conductance are ill suited to drive the parasitic capacitance of coaxial conductors used in cryogenic environments, necessitating a cryogenic amplification stage. We will compare two amplifiers based on single-transistor circuits implemented with silicon germanium heterojunction bipolar transistors. Both amplifiers provide gain at low power levels, but the dynamics of each circuit vary significantly. We will explore the gain mechanisms, linearity, and noise of each circuit and explain the situations in which each amplifier is best used. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

Drug response in a genetically engineered mouse model of multiple myeloma is predictive of clinical efficacy

PubMed Central

Chesi, Marta; Matthews, Geoffrey M.; Garbitt, Victoria M.; Palmer, Stephen E.; Shortt, Jake; Lefebure, Marcus; Stewart, A. Keith; Johnstone, Ricky W.

2012-01-01

The attrition rate for anticancer drugs entering clinical trials is unacceptably high. For multiple myeloma (MM), we postulate that this is because of preclinical models that overemphasize the antiproliferative activity of drugs, and clinical trials performed in refractory end-stage patients. We validate the Vk*MYC transgenic mouse as a faithful model to predict single-agent drug activity in MM with a positive predictive value of 67% (4 of 6) for clinical activity, and a negative predictive value of 86% (6 of 7) for clinical inactivity. We identify 4 novel agents that should be prioritized for evaluation in clinical trials. Transplantation of Vk*MYC tumor cells into congenic mice selected for a more aggressive disease that models end-stage drug-resistant MM and responds only to combinations of drugs with single-agent activity in untreated Vk*MYC MM. We predict that combinations of standard agents, histone deacetylase inhibitors, bromodomain inhibitors, and hypoxia-activated prodrugs will demonstrate efficacy in the treatment of relapsed MM. PMID:22451422

Broad specification fuels technology program, phase 1

NASA Technical Reports Server (NTRS)

Lohmann, R. P.; Jeroszko, R. A.

1982-01-01

An experimental evaluation was conducted to assess the impact of the use of broadened properties fuels on combustor design concepts. Emphasis was placed on establishing the viability of design modifications to current combustor concepts and the use of advanced technology concepts to facilitate operation on Experimental Referee Broad Specification (ERBS) fuel while meeting exhaust emissions and performance specifications and maintaining acceptable durability. Three different combustor concepts, representative of progressively more aggressive technology levels, were evaluated. When operated on ERBS rather than Jet A fuel, a single stage combustor typical of that in the most recent versions of the JT9D-7 engine was found to produce excess carbon monoxide emissions at idle and elevated liner temperatures at high power levels that were projected to reduced liner life by 13 percent. The introduction of improved component technology, such as refined fuel injectors and advanced liner cooling concepts were shown to have the potential of enhancing the fuel flexibility of the single stage combustor.

Single-Cell RNA-Seq Analysis Maps Development of Human Germline Cells and Gonadal Niche Interactions.

PubMed

Li, Li; Dong, Ji; Yan, Liying; Yong, Jun; Liu, Xixi; Hu, Yuqiong; Fan, Xiaoying; Wu, Xinglong; Guo, Hongshan; Wang, Xiaoye; Zhu, Xiaohui; Li, Rong; Yan, Jie; Wei, Yuan; Zhao, Yangyu; Wang, Wei; Ren, Yixin; Yuan, Peng; Yan, Zhiqiang; Hu, Boqiang; Guo, Fan; Wen, Lu; Tang, Fuchou; Qiao, Jie

2017-06-01

Human fetal germ cells (FGCs) are precursors to sperm and eggs and are crucial for maintenance of the species. However, the developmental trajectories and heterogeneity of human FGCs remain largely unknown. Here we performed single-cell RNA-seq analysis of over 2,000 FGCs and their gonadal niche cells in female and male human embryos spanning several developmental stages. We found that female FGCs undergo four distinct sequential phases characterized by mitosis, retinoic acid signaling, meiotic prophase, and oogenesis. Male FGCs develop through stages of migration, mitosis, and cell-cycle arrest. Individual embryos of both sexes simultaneously contain several subpopulations, highlighting the asynchronous and heterogeneous nature of FGC development. Moreover, we observed reciprocal signaling interactions between FGCs and their gonadal niche cells, including activation of the bone morphogenic protein (BMP) and Notch signaling pathways. Our work provides key insights into the crucial features of human FGCs during their highly ordered mitotic, meiotic, and gametogenetic processes in vivo. Copyright © 2017 Elsevier Inc. All rights reserved.

High-power single-stage thulium-doped superfluorescent fiber source

NASA Astrophysics Data System (ADS)

Hu, Z. Y.; Yan, P.; Liu, Q.; Ji, E. C.; Xiao, Q. R.; Gong, M. L.

2015-01-01

In this paper, we report a high-power thulium (Tm)-doped superfluorescent fiber source (SFS) in the 2-μm spectral region. The SFS is based on double angle-cleaved facet operation and uses a simple single-stage geometry. The copropagating amplified spontaneous emission (ASE) yields a maximum output of 20.7 W at a center wavelength of 1,960.7 nm, with a full width at half maximum (FWHM) of ~45 nm. The counterpropagating ASE yields a maximum output of 25.2 W at a center wavelength of 1,948.2 nm, with a FWHM of ~50 nm. The maximum combined output of the SFS is as much as 45.9 W, which corresponds to a slope efficiency of 38.9 %. In addition, a model of the ~2 μm SFS in Tm-doped silica fibers pumped at ~790 nm is developed, and the influence of fiber length and end-facet reflectivity on the ASE output performance and the parasitic lasing threshold are studied numerically.

Effect of reservoir zones and hedging factor dynamism on reservoir adaptive capacity for climate change impacts

NASA Astrophysics Data System (ADS)

Adeloye, Adebayo J.; Soundharajan, Bankaru-Swamy

2018-06-01

When based on the zones of available water in storage, hedging has traditionally used a single hedged zone and a constant rationing ratio for constraining supply during droughts. Given the usual seasonality of reservoir inflows, it is also possible that hedging could feature multiple hedged zones and temporally varying rationing ratios but very few studies addressing this have been reported especially in relation to adaptation to projected climate change. This study developed and tested Genetic Algorithms (GA) optimised zone-based operating policies of various configurations using data for the Pong reservoir, Himachal Pradesh, India. The results show that hedging does lessen vulnerability, which dropped from ≥ 60 % without hedging to below 25 % with the single stage hedging. More complex hedging policies, e.g. two stage and/or temporally varying rationing ratios only produced marginal improvements in performance. All this shows that water hedging policies do not have to be overly complex to effectively offset reservoir vulnerability caused by water shortage resulting from e.g. projected climate change.

High Performance Pulse Tube Cryocoolers

NASA Astrophysics Data System (ADS)

Olson, J. R.; Roth, E.; Champagne, P.; Evtimov, B.; Nast, T. C.

2008-03-01

Lockheed Martin's Advanced Technology Center has been developing pulse tube cryocoolers for more than ten years. Recent innovations include successful testing of four-stage coldheads, no-load temperature below 4 K, and the recent development of a high-efficiency compressor. This paper discusses the predicted performance of single and multiple stage pulse tube coldheads driven by our new 6 kg "M5Midi" compressor, which is capable of 90% efficiency with 200 W input power, and a maximum input power of 1000 W. This compressor retains the simplicity of earlier LM-ATC compressors: it has a moving magnet and an external electrical coil, minimizing organics in the working gas and requiring no electrical penetrations through the pressure wall. Motor losses were minimized during design, resulting in a simple, easily-manufactured compressor with state-of-the-art motor efficiency. The predicted cryocooler performance is presented as simple formulae, allowing an engineer to include the impact of a highly-optimized cryocooler into a full system analysis. Performance is given as a function of the heat rejection temperature and the cold tip temperatures and cooling loads.

Heat transfer and performance characteristics of axial cooling fans with downstream guide vanes

NASA Astrophysics Data System (ADS)

Terzis, Alexandros; Stylianou, Ioannis; Kalfas, Anestis I.; Ott, Peter

2012-04-01

This study examines experimentally the effect of stators on the performance and heat transfer characteristics of small axial cooling fans. A single fan impeller, followed by nine stator blades in the case of a complete stage, was used for all the experimental configurations. Performance measurements were carried out in a constant speed stage performance test rig while the transient liquid crystal technique was used for the heat transfer measurements. Full surface heat transfer coefficient distributions were obtained by recording the temperature history of liquid crystals on a target plate. The experimental data indicated that the results are highly affected by the flow conditions at the fan outlet. Stators can be beneficial in terms of pressure drop and efficiency, and thus more economical operation, as well as, in the local heat transfer distribution at the wake of the stator blades if the fan is installed very close to the cooling object. However, as the separation distance increases, enhanced heat transfer rate in the order of 25% is observed in the case of the fan impeller.

A Modified Penalty Parameter Approach for Optimal Estimation of UH with Simultaneous Estimation of Infiltration Parameters

NASA Astrophysics Data System (ADS)

Bhattacharjya, Rajib Kumar

2018-05-01

The unit hydrograph and the infiltration parameters of a watershed can be obtained from observed rainfall-runoff data by using inverse optimization technique. This is a two-stage optimization problem. In the first stage, the infiltration parameters are obtained and the unit hydrograph ordinates are estimated in the second stage. In order to combine this two-stage method into a single stage one, a modified penalty parameter approach is proposed for converting the constrained optimization problem to an unconstrained one. The proposed approach is designed in such a way that the model initially obtains the infiltration parameters and then searches the optimal unit hydrograph ordinates. The optimization model is solved using Genetic Algorithms. A reduction factor is used in the penalty parameter approach so that the obtained optimal infiltration parameters are not destroyed during subsequent generation of genetic algorithms, required for searching optimal unit hydrograph ordinates. The performance of the proposed methodology is evaluated by using two example problems. The evaluation shows that the model is superior, simple in concept and also has the potential for field application.

Experimental Vibration Damping Characteristics of the Third-stage Rotor of a Three-stage Transonic Axial-flow Compressor

NASA Technical Reports Server (NTRS)

Newman, Frederick A.

1988-01-01

Rotor blade aerodynamic damping is experimentally determined in a three-stage transonic axial flow compressor having design aerodynamic performance goals of 4.5:1 pressure ratio and 65.5 lbm/sec weight flow. The combined damping associated with each mode is determined by a least squares fit of a single degree of freedom system transfer function to the nonsynchronous portion of the rotor blade strain gage output power spectra. The combined damping consists of the aerodynamic damping and the structural and mechanical damping. The aerodynamic damping varies linearly with the inlet total pressure for a given corrected speed, weight flow, and pressure ratio while the structural and mechanical damping is assumed to remain constant. The combined damping is determined at three inlet total pressure levels to obtain the aerodynamic damping. The third-stage rotor blade aerodynamic damping is presented and discussed for the design equivalent speed with the stator blades reset for maximum efficiency. The compressor overall preformance and experimental Campbell diagrams for the third-stage rotor blade row are also presented.

Vibration isolation and dual-stage actuation pointing system for space precision payloads

NASA Astrophysics Data System (ADS)

Kong, Yongfang; Huang, Hai

2018-02-01

Pointing and stability requirements for future space missions are becoming more and more stringent. This work follows the pointing control method which consists of a traditional spacecraft attitude control system and a payload active pointing loop, further proposing a vibration isolation and dual-stage actuation pointing system for space precision payloads based on a soft Stewart platform. Central to the concept is using the dual-stage actuator instead of the traditional voice coil motor single-stage actuator to improve the payload active pointing capability. Based on a specified payload, the corresponding platform was designed to be installed between the spacecraft bus and the payload. The performance of the proposed system is demonstrated by preliminary closed-loop control investigations in simulations. With the ordinary spacecraft bus, the line-of-sight pointing accuracy can be controlled to below a few milliarcseconds in tip and tilt. Meanwhile, utilizing the voice coil motor with the softening spring in parallel, which is a portion of the dual-stage actuator, the system effectively achieves low-frequency motion transmission and high-frequency vibration isolation along the other four degree-of-freedom directions.

A Bayesian predictive two-stage design for phase II clinical trials.

PubMed

Sambucini, Valeria

2008-04-15

In this paper, we propose a Bayesian two-stage design for phase II clinical trials, which represents a predictive version of the single threshold design (STD) recently introduced by Tan and Machin. The STD two-stage sample sizes are determined specifying a minimum threshold for the posterior probability that the true response rate exceeds a pre-specified target value and assuming that the observed response rate is slightly higher than the target. Unlike the STD, we do not refer to a fixed experimental outcome, but take into account the uncertainty about future data. In both stages, the design aims to control the probability of getting a large posterior probability that the true response rate exceeds the target value. Such a probability is expressed in terms of prior predictive distributions of the data. The performance of the design is based on the distinction between analysis and design priors, recently introduced in the literature. The properties of the method are studied when all the design parameters vary.

Ambient temperature cadmium zinc telluride radiation detector and amplifier circuit

DOEpatents

McQuaid, J.H.; Lavietes, A.D.

1998-05-26

A low noise, low power consumption, compact, ambient temperature signal amplifier for a Cadmium Zinc Telluride (CZT) radiation detector is disclosed. The amplifier can be used within a larger system (e.g., including a multi-channel analyzer) to allow isotopic analysis of radionuclides in the field. In one embodiment, the circuit stages of the low power, low noise amplifier are constructed using integrated circuit (IC) amplifiers , rather than discrete components, and include a very low noise, high gain, high bandwidth dual part preamplification stage, an amplification stage, and an filter stage. The low noise, low power consumption, compact, ambient temperature amplifier enables the CZT detector to achieve both the efficiency required to determine the presence of radionuclides and the resolution necessary to perform isotopic analysis to perform nuclear material identification. The present low noise, low power, compact, ambient temperature amplifier enables a CZT detector to achieve resolution of less than 3% full width at half maximum at 122 keV for a Cobalt-57 isotope source. By using IC circuits and using only a single 12 volt supply and ground, the novel amplifier provides significant power savings and is well suited for prolonged portable in-field use and does not require heavy, bulky power supply components. 9 figs.

Deep-cascade: Cascading 3D Deep Neural Networks for Fast Anomaly Detection and Localization in Crowded Scenes.

PubMed

Sabokrou, Mohammad; Fayyaz, Mohsen; Fathy, Mahmood; Klette, Reinhard

2017-02-17

This paper proposes a fast and reliable method for anomaly detection and localization in video data showing crowded scenes. Time-efficient anomaly localization is an ongoing challenge and subject of this paper. We propose a cubicpatch- based method, characterised by a cascade of classifiers, which makes use of an advanced feature-learning approach. Our cascade of classifiers has two main stages. First, a light but deep 3D auto-encoder is used for early identification of "many" normal cubic patches. This deep network operates on small cubic patches as being the first stage, before carefully resizing remaining candidates of interest, and evaluating those at the second stage using a more complex and deeper 3D convolutional neural network (CNN). We divide the deep autoencoder and the CNN into multiple sub-stages which operate as cascaded classifiers. Shallow layers of the cascaded deep networks (designed as Gaussian classifiers, acting as weak single-class classifiers) detect "simple" normal patches such as background patches, and more complex normal patches are detected at deeper layers. It is shown that the proposed novel technique (a cascade of two cascaded classifiers) performs comparable to current top-performing detection and localization methods on standard benchmarks, but outperforms those in general with respect to required computation time.

ECL-IAA and ECL-GADA Can Identify High-Risk Single Autoantibody-Positive Relatives in the TrialNet Pathway to Prevention Study.

PubMed

Steck, Andrea K; Fouts, Alexandra; Miao, Dongmei; Zhao, Zhiyuan; Dong, Fran; Sosenko, Jay; Gottlieb, Peter; Rewers, Marian J; Yu, Liping

2016-07-01

Relatives with single positive islet autoantibodies have a much lower risk of progression to diabetes than those with multiple autoantibodies. TrialNet subjects positive for single autoantibody to insulin (mIAA) (n = 50) or single autoantibody to glutamic acid decarboxylase (GADA) (n = 50) were analyzed using new electrochemiluminescence (ECL) assays (ECL-IAA and ECL-GADA, respectively) at their initial visit and longitudinally over time. Affinity assays were performed on a subset of single autoantibody-positive subjects at initial and most recent visits. After a mean follow-up of 5.3 years, 20 subjects developed type 1 diabetes. Among either single GADA or single mIAA subjects, those who were positive in the ECL assay showed higher affinity at the initial visit, and affinity results stayed consistent over time. No converting events from low to high or high to low affinity were seen over time. Confirmed positivity for ECL is associated with high affinity and can help staging of risk for type 1 diabetes in single autoantibody-positive subjects.

One vs two primary LOX feedline configuration study for the National Launch System

NASA Technical Reports Server (NTRS)

Dill, K.; Davis, D.; Bates, R.; Tarwater, R.

1992-01-01

Six single LOX feedline designs were evaluated for use on the National Launch Vehicle. A single feedline design, designated the 'Spider', was chosen and compared to the baseline system. The baseline configuration employs two 20-inch I.D. lines, each supplying LOX to three 650,000 lbf thrust Space Transportation Main Engines. Five single feedline diameters were examined for the spider configuration; 22, 24, 26, 28, and 30-inch I.D. System dry weights and LOX residuals were estimated. These parameters, along with calculated staged mass for the different single line and baseline configurations, were used to calculate the payload mass to orbit. For the cases where LOX is drained to minimum NPSP conditions, none of the single lines performed as well as the dual line system, although the 22-inch diameter single line compared well. However, for the cases where LOX is drained to operating levels (LOX level at the booster and spider manifolds for the dual and single line configurations, respectively), the 22 - 26-inch I.D. single line systems show a greater payload capability.

Feasibility and Performance of the Microwave Thermal Rocket Launcher

NASA Astrophysics Data System (ADS)

Parkin, Kevin L. G.; Culick, Fred E. C.

2004-03-01

Beamed-energy launch concepts employing a microwave thermal thruster are feasible in principle, and microwave sources of sufficient power to launch tons into LEO already exist. Microwave thermal thrusters operate on an analogous principle to nuclear thermal thrusters, which have experimentally demonstrated specific impulses exceeding 850 seconds. Assuming such performance, simple application of the rocket equation suggests that payload fractions of 10% are possible for a single stage to orbit (SSTO) microwave thermal rocket. We present an SSTO concept employing a scaled X-33 aeroshell. The flat aeroshell underside is covered by a thin-layer microwave absorbent heat-exchanger that forms part of the thruster. During ascent, the heat-exchanger faces the microwave beam. A simple ascent trajectory analysis incorporating X-33 aerodynamic data predicts a 10% payload fraction for a 1 ton craft of this type. In contrast, the Saturn V had 3 non-reusable stages and achieved a payload fraction of 4%.

Optimization of Adaboost Algorithm for Sonar Target Detection in a Multi-Stage ATR System

NASA Technical Reports Server (NTRS)

Lin, Tsung Han (Hank)

2011-01-01

JPL has developed a multi-stage Automated Target Recognition (ATR) system to locate objects in images. First, input images are preprocessed and sent to a Grayscale Optical Correlator (GOC) filter to identify possible regions-of-interest (ROIs). Second, feature extraction operations are performed using Texton filters and Principal Component Analysis (PCA). Finally, the features are fed to a classifier, to identify ROIs that contain the targets. Previous work used the Feed-forward Back-propagation Neural Network for classification. In this project we investigate a version of Adaboost as a classifier for comparison. The version we used is known as GentleBoost. We used the boosted decision tree as the weak classifier. We have tested our ATR system against real-world sonar images using the Adaboost approach. Results indicate an improvement in performance over a single Neural Network design.

Small axial compressor technology, volume 1

NASA Technical Reports Server (NTRS)

Holman, F. F.; Kidwell, J. R.; Ware, T. C.

1976-01-01

A scaled single-stage, highly-loaded, axial-flow transonic compressor was tested at speeds from 70 to 110% design equivalent speed to evaluate the effects of scaling compromises and the individual and combined effects of rotor tip running clearance and rotor shroud casing treatment on the overall and blade element performance. At design speed and 1% tip clearance the stage demonstrated an efficiency of 83.2% at 96.4% design flow and a pressure ratio of 1.865. Casing treatment increased design speed surge margin 2.0 points to 12.8%. Overall performance was essentially unchanged. An increase in rotor running clearance to 2.2%, with smooth casing, reduced design speed peak efficiency 5.7 points, flow by 7.4%, pressure ratio to 1.740, and surge margin to 5.4%. Reinstalling casing treatment regained 3.5 points in design speed peak efficiency, 4.7% flow, increased pressure ratio to 1.800 and surge margin to 8.7%.

Ovarian Cancer Stage I

MedlinePlus

... Stage I Description: Three-panel drawing of stage IA, IB, and IC; the first panel (stage IA) shows cancer inside one ovary. The second panel ( ... fallopian tubes, uterus, cervix, and vagina. In stage IA, cancer is found inside a single ovary or ...

A Two-Stage-to-Orbit Spaceplane Concept With Growth Potential

NASA Technical Reports Server (NTRS)

Mehta, Unmeel B.; Bowles, Jeffrey V.

2001-01-01

A two-stage-to-orbit (TSTO) spaceplane concept developed in 1993 is revisited, and new information is provided to assist in the development of the next-generation space transportation vehicles. The design philosophy, TSTO spaceplane concept, and the design method are briefly described. A trade study between cold and hot structures leads to the choice of cold structures with external thermal protection systems. The optimal Mach number for staging the second stage of the TSTO spaceplane (with air-breathing propulsion on the first stage) is 10, based on life-cycle cost analysis. The performance and specification of a prototype/experimental (P/X) TSTO spaceplane with a turbo/ram/scramjet propulsion system and built-in growth potential are presented and discussed. The internal rate of return on investment is the highest for the proposed TSTO spaceplane, vis-A-vis a single-stage-to-orbit (SSTO) rocket vehicle and a TSTO spaceplane without built-in growth. Additional growth potentials for the proposed spaceplane are suggested. This spaceplane can substantially decrease access-to-space cost and risk, and increase safety and reliability in the near term It can be a serious candidate for the next-generation space transportation system.

Optimized FPGA Implementation of Multi-Rate FIR Filters Through Thread Decomposition

NASA Technical Reports Server (NTRS)

Zheng, Jason Xin; Nguyen, Kayla; He, Yutao

2010-01-01

Multirate (decimation/interpolation) filters are among the essential signal processing components in spaceborne instruments where Finite Impulse Response (FIR) filters are often used to minimize nonlinear group delay and finite-precision effects. Cascaded (multi-stage) designs of Multi-Rate FIR (MRFIR) filters are further used for large rate change ratio, in order to lower the required throughput while simultaneously achieving comparable or better performance than single-stage designs. Traditional representation and implementation of MRFIR employ polyphase decomposition of the original filter structure, whose main purpose is to compute only the needed output at the lowest possible sampling rate. In this paper, an alternative representation and implementation technique, called TD-MRFIR (Thread Decomposition MRFIR), is presented. The basic idea is to decompose MRFIR into output computational threads, in contrast to a structural decomposition of the original filter as done in the polyphase decomposition. Each thread represents an instance of the finite convolution required to produce a single output of the MRFIR. The filter is thus viewed as a finite collection of concurrent threads. The technical details of TD-MRFIR will be explained, first showing its applicability to the implementation of downsampling, upsampling, and resampling FIR filters, and then describing a general strategy to optimally allocate the number of filter taps. A particular FPGA design of multi-stage TD-MRFIR for the L-band radar of NASA's SMAP (Soil Moisture Active Passive) instrument is demonstrated; and its implementation results in several targeted FPGA devices are summarized in terms of the functional (bit width, fixed-point error) and performance (time closure, resource usage, and power estimation) parameters.

Performance and safety of collagenated xenogeneic bone block for lateral alveolar ridge augmentation and staged implant placement. A monocenter, prospective single-arm clinical study.

PubMed

Schwarz, Frank; Mihatovic, Ilja; Ghanaati, Shahram; Becker, Jürgen

2017-08-01

To assess the clinical safety and performance of collagenated xenogeneic bone block (CXBB) for lateral alveolar ridge augmentation and two-stage implant placement. In ten patients exhibiting a single-tooth gap, the surgical procedure included the preparation of mucoperiosteal flaps, a rigid fixation of CXBB (Geistlich Bio-Graft ® ) using an osteosynthesis screw, and contour augmentation. After 24 weeks of submerged healing, the primary endpoint was defined as the final ridge width sufficient to place an adequately dimensioned titanium implant at the respective sites. Secondary outcomes included, for example, the gain in ridge width (mm). Clinical parameters (e.g., bleeding on probing - BOP, probing depth - PD, mucosal recession - MR) were assessed immediately after the cementation of the crown and at the final visit. At 24 weeks, implant placement could be achieved in 8 of 10 patients exhibiting a mean gain in ridge width (mean ± SD) of 3.88 ± 1.75 mm. Histological analysis has pointed to a homogeneous osseous organization of CXBB. The changes of mean BOP, PD, and MR values at the final visit amounted to 16.62 ± 32.02%, 0.04 ± 0.21 mm, and -0.04 ± 0.12 mm, respectively. CXBB may be successfully used to support lateral alveolar ridge augmentation and two-stage implant placement. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Performance of Axial-Flow Supersonic Compressor on XJ-55-FF-1 Turbojet Engine. I - Preliminary Performance of Compressor. 1; Preliminary Performance of Compressor

NASA Technical Reports Server (NTRS)

Hartmann, Melvin J.; Graham, Robert C.

1949-01-01

An investigation was conducted to determine the performance characteristics of the axial-flow supersonic compressor of the XJ-55-FF-1 turbo Jet engine. The test unit consisted of a row of inlet guide vanes and a supersonic rotor; the stator vanes after the rotor were omitted. The maximum pressure ratio produced in the single stage was 2.28 at an equivalent tip speed or 1814 feet per second with an adiabatic efficiency of approximately 0.61, equivalent weight flow of 13.4 pounds per second. The maximum efficiency of 0.79 was obtained at an equivalent tip speed of 801 feet per second.

The effect of ASE reinjection configuration through FBGs on the gain and noise figure performance of L-Band EDFA

NASA Astrophysics Data System (ADS)

Durak, Fırat Ertaç; Altuncu, Ahmet

2017-03-01

In this study, we present the gain and noise figure performance improvement in L-band erbium-doped fiber amplifier (L-EDFA) provided by amplified spontaneous emission (ASE) reinjection through different configurations of 1533 nm band FBGs. The experimental results are compared with a single-stage bidirectionally pumped conventional L-EDFA design. It is shown that when the forward and/or the backward ASE noise is partly reinjected to L-EDFA using a double/single 1533 nm fiber Bragg gratings (FBG), the gain and noise figure performance of L-EDFA increases depending on the FBG configuration. The best gain and NF performance in our L-EDFA was achieved by reinjection of forward and backward ASE through FBG1 and FBG2 leading to an 4.5 dB increase in gain and 1 dB decrease in NF at 1585 nm and -30 dBm input signal power. The results show that both FBGs must be used at the same time to improve gain and NF performance in L-band EDFAs.

Transrectal ultrasonography-guided biopsy does not reliably identify dominant cancer location in men with low-risk prostate cancer.

PubMed

Washington, Samuel L; Bonham, Michael; Whitson, Jared M; Cowan, Janet E; Carroll, Peter R

2012-07-01

Study Type - Diagnostic (exploratory cohort) Level of Evidence 2b What's known on the subject? and What does the study add? The widespread use of serum PSA testing followed by TRUS-guided biopsy have resulted in profound prostate cancer stage migration with many patients presenting with focal rather than multifocal disease. There is increasing interest in the use of focal rather than whole-gland treatment. However, current biopsy schemes may still miss cancer or, even when cancer is identified, its extent or grade might not be accurately characterized. In order for focal therapy to be effective, the area of highest tumour volume and/or grade needs to localized accurately. The aim of this study was to assess how well biopsy, as currently performed, locates the focus of highest prostate cancer volume and/or grade. To evaluate the ability of transrectal ultrasonography (TRUS)-guided extended core biopsy to identify the dominant tumour accurately in men with early stage prostate cancer. Patients with early stage, low-risk prostate cancer who subsequently underwent radical prostatectomy (RP) and had complete surgical specimens were identified. Re-review was performed by a single uropathologist using ImageJ software to identify tumour location, dominant grade (DG) and dominant volume (DV). Pathology findings were then compared with biopsy results. A total of 51 men with early stage, low-risk prostate cancer, who had undergone RP, had complete specimens for review and a median of 15 biopsy cores taken for diagnosis and grading. Sixteen men had a single diagnostic biopsy, 21 had one repeat biopsy, and 14 had two or more repeat biopsies. Compared with surgical findings, biopsy correctly identified the sextant with the largest tumour volume in 55% (95% CI 0.5-0.6) of specimens and the highest grade in 37% (95 CI 0.3-0.5). No demographic or clinical factors were significantly associated with identification of DG. Interval between last biopsy and RP, total tissue length taken and total length of tumour identified were significantly associated with correct identification of DV. Our findings show that TRUS-guided biopsy detects and localizes DV better than it does DG. Even with an extended scheme, TRUS-guided biopsy does not reliably identify dominant cancer location in this low-risk cohort of men with early stage prostate cancer. TRUS-guided biopsy may perform better in similar men with low stage, but higher volume disease. © 2011 BJU INTERNATIONAL.

Preprocedural Anxiety and Pain Perception Following Root Surface Debridement in Chronic Periodontitis Patients.

PubMed

Naik, Vanaja Krishna; Balasundaram, Aruna; Appukuttan, Devapriya; Nainar, Deepavalli Arumuga; Milward, Michael Robert; Victor, Dhayanand John; Junaid, Mohammed

2018-01-01

The aim of this study was to evaluate and compare preprocedural dental anxiety levels and postprocedural pain perception in chronic periodontitis patients during conventional-staged root surface debridement (RSD) and single-stage RSD. Thirty-seven adult generalized chronic periodontitis patients requiring RSD were recruited in this study. Preprocedural anxiety levels were assessed using a self-reported questionnaire and postprocedural pain perceptions were assessed using 0-10 cm visual analog scale. The subject population was divided into two groups: staged RSD ( n = 18) and single-stage RSD ( n = 19). Staged RSD patients visited four times as opposed to single-stage RSD patients. Data were subjected to Pearson Chi-square test, Mann-Whitney U-test, and Spearman's rank correlation. There was no statistically significant difference in dental anxiety levels or pain perceptions in both the groups. Within Group 1, there was statistical significant difference in dental anxiety levels between visit 4 and visit 3 ( P = 0.037) and pain perception between visit 3 and visit 1 ( P = 0.005), visit 4 and visit 1 ( P = 0.002), and visit 4 and visit 2 (0.04) was statistically significant. There was a positive correlation of anxiety questionnaire (Q1-Q4) to the pain score in Group 1 which was statistically significant and in single-stage RSD. Conventional quadrant-wise RSD tends to cognitively condition the anxiety experience thus influencing pain experience.

Radiofrequency ablation versus resection for Barcelona clinic liver cancer very early/early stage hepatocellular carcinoma: a systematic review.

PubMed

He, Zhen-Xin; Xiang, Pu; Gong, Jian-Ping; Cheng, Nan-Sheng; Zhang, Wei

2016-01-01

To compare the long-term survival outcomes of radiofrequency ablation and liver resection for single very early/early stage hepatocellular carcinoma (HCC). The Cochrane Library (Issue 3, 2015), Embase (1974 to March 15, 2015), PubMed (1950 to March 15, 2015), Web of Science (1900 to March 15, 2015), and Chinese Biomedical Literature Database (1978 to March 15, 2015) were searched to identify relevant trials. Only trials that compared radiofrequency ablation and liver resection for single very early stage (≤2 cm) or early stage (≤3 cm) HCC according to the Barcelona clinic liver cancer (BCLC) staging system were considered for inclusion in this review. The primary outcomes that we analyzed were the 3-year and 5-year overall survival (OS) rates, and the secondary outcomes that we analyzed were the 3-year and 5-year disease-free survival (DFS) rates. Review Manager 5.3 was used to perform a cumulative meta-analysis. Possible publication bias was examined using a funnel plot. A random-effects model was applied to summarize the various outcomes. Six studies involving 947 patients were identified that compared radiofrequency ablation (n=528) to liver resection (n=419) for single BCLC very early HCC. In these six studies, the rates of 3-year OS, 5-year OS, 3-year DFS, and 5-year DFS were significantly lower in the radiofrequency ablation group than in the liver resection group (risk ratio [RR] =0.90, 95% confidence interval [CI]: 0.83-0.98, P=0.01; RR =0.84, 95% CI: 0.75-0.95, P=0.004; RR =0.77, 95% CI: 0.60-0.98, P=0.04; and RR =0.70, 95% CI: 0.52-0.94, P=0.02, respectively). Ten studies involving 2,501 patients were identified that compared radiofrequency ablation (n=1,476) to liver resection (n=1,025) for single BCLC early HCC. In these ten studies, the rates of 3-year OS, 5-year OS, 3-year DFS, and 5-year DFS were also significantly lower in the radiofrequency ablation group than in the liver resection group (RR =0.93, 95% CI: 0.88-0.98, P=0.003; RR =0.84, 95% CI: 0.75-0.94, P=0.002; RR =0.72, 95% CI: 0.58-0.89, P=0.002; and RR =0.47, 95% CI: 0.33-0.67, P<0.0001, respectively). The long-term survival outcomes for patients with single BCLC very early/early stage HCC appear to be superior after liver resection compared to radiofrequency ablation.

Radiofrequency ablation versus resection for Barcelona clinic liver cancer very early/early stage hepatocellular carcinoma: a systematic review

PubMed Central

He, Zhen-Xin; Xiang, Pu; Gong, Jian-Ping; Cheng, Nan-Sheng; Zhang, Wei

2016-01-01

Aim To compare the long-term survival outcomes of radiofrequency ablation and liver resection for single very early/early stage hepatocellular carcinoma (HCC). Methods The Cochrane Library (Issue 3, 2015), Embase (1974 to March 15, 2015), PubMed (1950 to March 15, 2015), Web of Science (1900 to March 15, 2015), and Chinese Biomedical Literature Database (1978 to March 15, 2015) were searched to identify relevant trials. Only trials that compared radiofrequency ablation and liver resection for single very early stage (≤2 cm) or early stage (≤3 cm) HCC according to the Barcelona clinic liver cancer (BCLC) staging system were considered for inclusion in this review. The primary outcomes that we analyzed were the 3-year and 5-year overall survival (OS) rates, and the secondary outcomes that we analyzed were the 3-year and 5-year disease-free survival (DFS) rates. Review Manager 5.3 was used to perform a cumulative meta-analysis. Possible publication bias was examined using a funnel plot. A random-effects model was applied to summarize the various outcomes. Results Six studies involving 947 patients were identified that compared radiofrequency ablation (n=528) to liver resection (n=419) for single BCLC very early HCC. In these six studies, the rates of 3-year OS, 5-year OS, 3-year DFS, and 5-year DFS were significantly lower in the radiofrequency ablation group than in the liver resection group (risk ratio [RR] =0.90, 95% confidence interval [CI]: 0.83–0.98, P=0.01; RR =0.84, 95% CI: 0.75–0.95, P=0.004; RR =0.77, 95% CI: 0.60–0.98, P=0.04; and RR =0.70, 95% CI: 0.52–0.94, P=0.02, respectively). Ten studies involving 2,501 patients were identified that compared radiofrequency ablation (n=1,476) to liver resection (n=1,025) for single BCLC early HCC. In these ten studies, the rates of 3-year OS, 5-year OS, 3-year DFS, and 5-year DFS were also significantly lower in the radiofrequency ablation group than in the liver resection group (RR =0.93, 95% CI: 0.88–0.98, P=0.003; RR =0.84, 95% CI: 0.75–0.94, P=0.002; RR =0.72, 95% CI: 0.58–0.89, P=0.002; and RR =0.47, 95% CI: 0.33–0.67, P<0.0001, respectively). Conclusion The long-term survival outcomes for patients with single BCLC very early/early stage HCC appear to be superior after liver resection compared to radiofrequency ablation. PMID:26966370

Dorsolateral prefrontal cortex bridges bilateral primary somatosensory cortices during cross-modal working memory.

PubMed

Zhao, Di; Ku, Yixuan

2018-05-01

Neural activity in the dorsolateral prefrontal cortex (DLPFC) has been suggested to integrate information from distinct sensory areas. However, how the DLPFC interacts with the bilateral primary somatosensory cortices (SIs) in tactile-visual cross-modal working memory has not yet been established. In the present study, we applied single-pulse transcranial magnetic stimulation (sp-TMS) over the contralateral DLPFC and bilateral SIs of human participants at various time points, while they performed a tactile-visual delayed matching-to-sample task with a 2-second delay. sp-TMS over the contralateral DLPFC or the contralateral SI at either an sensory encoding stage [i.e. 100 ms after the onset of a vibrotactile sample stimulus (200-ms duration)] or an early maintenance stage (i.e. 300 ms after the onset), significantly impaired the accuracy of task performance; sp-TMS over the contralateral DLPFC or the ipsilateral SI at a late maintenance stage (1600 ms and 1900 ms) also significantly disrupted the performance. Furthermore, at 300 ms after the onset of the vibrotactile sample stimulus, there was a significant correlation between the deteriorating effects of sp-TMS over the contralateral SI and the contralateral DLPFC. These results imply that the DLPFC and the bilateral SIs play causal roles at distinctive stages during cross-modal working memory, while the contralateral DLPFC communicates with the contralateral SI in the early delay, and cooperates with the ipsilateral SI in the late delay. Copyright © 2018 Elsevier B.V. All rights reserved.

Perception-based 3D tactile rendering from a single image for human skin examinations by dynamic touch.

PubMed

Kim, K; Lee, S

2015-05-01

Diagnosis of skin conditions is dependent on the assessment of skin surface properties that are represented by more tactile properties such as stiffness, roughness, and friction than visual information. Due to this reason, adding tactile feedback to existing vision based diagnosis systems can help dermatologists diagnose skin diseases or disorders more accurately. The goal of our research was therefore to develop a tactile rendering system for skin examinations by dynamic touch. Our development consists of two stages: converting a single image to a 3D haptic surface and rendering the generated haptic surface in real-time. Converting to 3D surfaces from 2D single images was implemented with concerning human perception data collected by a psychophysical experiment that measured human visual and haptic sensibility to 3D skin surface changes. For the second stage, we utilized real skin biomechanical properties found by prior studies. Our tactile rendering system is a standalone system that can be used with any single cameras and haptic feedback devices. We evaluated the performance of our system by conducting an identification experiment with three different skin images with five subjects. The participants had to identify one of the three skin surfaces by using a haptic device (Falcon) only. No visual cue was provided for the experiment. The results indicate that our system provides sufficient performance to render discernable tactile rendering with different skin surfaces. Our system uses only a single skin image and automatically generates a 3D haptic surface based on human haptic perception. Realistic skin interactions can be provided in real-time for the purpose of skin diagnosis, simulations, or training. Our system can also be used for other applications like virtual reality and cosmetic applications. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Solving Single Machine Total Weighted Tardiness Problem with Unequal Release Date Using Neurohybrid Particle Swarm Optimization Approach.

PubMed

Cakar, Tarik; Koker, Rasit

2015-01-01

A particle swarm optimization algorithm (PSO) has been used to solve the single machine total weighted tardiness problem (SMTWT) with unequal release date. To find the best solutions three different solution approaches have been used. To prepare subhybrid solution system, genetic algorithms (GA) and simulated annealing (SA) have been used. In the subhybrid system (GA and SA), GA obtains a solution in any stage, that solution is taken by SA and used as an initial solution. When SA finds better solution than this solution, it stops working and gives this solution to GA again. After GA finishes working the obtained solution is given to PSO. PSO searches for better solution than this solution. Later it again sends the obtained solution to GA. Three different solution systems worked together. Neurohybrid system uses PSO as the main optimizer and SA and GA have been used as local search tools. For each stage, local optimizers are used to perform exploitation to the best particle. In addition to local search tools, neurodominance rule (NDR) has been used to improve performance of last solution of hybrid-PSO system. NDR checked sequential jobs according to total weighted tardiness factor. All system is named as neurohybrid-PSO solution system.

Ion-beam assisted laser fabrication of sensing plasmonic nanostructures

PubMed Central

Kuchmizhak, Aleksandr; Gurbatov, Stanislav; Vitrik, Oleg; Kulchin, Yuri; Milichko, Valentin; Makarov, Sergey; Kudryashov, Sergey

2016-01-01

Simple high-performance, two-stage hybrid technique was developed for fabrication of different plasmonic nanostructures, including nanorods, nanorings, as well as more complex structures on glass substrates. In this technique, a thin noble-metal film on a dielectric substrate is irradiated by a single tightly focused nanosecond laser pulse and then the modified region is slowly polished by an accelerated argon ion (Ar+) beam. As a result, each nanosecond laser pulse locally modifies the initial metal film through initiation of fast melting and subsequent hydrodynamic processes, while the following Ar+-ion polishing removes the rest of the film, revealing the hidden topography features and fabricating separate plasmonic structures on the glass substrate. We demonstrate that the shape and lateral size of the resulting functional plasmonic nanostructures depend on the laser pulse energy and metal film thickness, while subsequent Ar+-ion polishing enables to vary height of the resulting nanostructures. Plasmonic properties of the fabricated nanostructures were characterized by dark-field micro-spectroscopy, Raman and photoluminescence measurements performed on single nanofeatures, as well as by supporting numerical calculations of the related electromagnetic near-fields and Purcell factors. The developed simple two-stage technique represents a new step towards direct large-scale laser-induced fabrication of highly ordered arrays of complex plasmonic nanostructures. PMID:26776569

Analytical evaluation of the impact of broad specification fuels on high bypass turbofan engine combustors

NASA Technical Reports Server (NTRS)

Lohmann, R. P.; Szetela, E. J.; Vranos, A.

1978-01-01

The impact of the use of broad specification fuels on the design, performance durability, emissions and operational characteristics of combustors for commercial aircraft gas turbine engines was assessed. Single stage, vorbix and lean premixed prevaporized combustors, in the JT9D and an advanced energy efficient engine cycle were evaluated when operating on Jet A and ERBS (Experimental Referee Broad Specification) fuels. Design modifications, based on criteria evolved from a literature survey, were introduced and their effectiveness at offsetting projected deficiencies resulting from the use of ERBS was estimated. The results indicate that the use of a broad specification fuel such as ERBS, will necessitate significant technology improvements and redesign if deteriorated performance, durability and emissions are to be avoided. Higher radiant heat loads are projected to seriously compromise liner life while the reduced thermal stability of ERBS will require revisions to the engine-airframe fuel system to reduce the thermal stress on the fuel. Smoke and emissions output are projected to increase with the use of broad specification fuels. While the basic geometry of the single stage and vorbix combustors are compatible with the use of ERBS, extensive redesign of the front end of the lean premixed prevaporized burner will be required to achieve satisfactory operation and optimum emissions.

Native kidney function following liver transplantation using calcineurin inhibitors: single-center analysis with 20 years of follow-up.

PubMed

LaMattina, John C; Mezrich, Joshua D; Fernandez, Luis A; D'Alessandro, Anthony M; Djamali, Arjang; Musat, Alexandru I; Pirsch, John D; Foley, David P

2013-01-01

The incidence of chronic kidney disease (CKD) in liver transplant recipients has been estimated to be from 18% to 28% at 10 yr after transplantation. As outcomes from liver transplantation continue to improve, long-term native kidney function in these recipients becomes more critical to patient survival. We analyzed 1151 adult, deceased-donor, single-organ primary liver transplantations performed at our center between 7/17/84 and 12/31/07. Analysis of renal function was performed on 972 patients with liver allograft survival >1 yr. Kaplan-Meier analysis revealed that 3%, 7%, and 18% of liver transplant recipients with allograft survival >1 yr developed end-stage renal disease (ESRD) at five, 10, and 20 yr, respectively. Significant independent risk factors for ESRD included dialysis during the transplant hospitalization, the stage of CKD at one yr, hypercholesterolemia, non-Caucasian race, and hepatitis C as the primary indication for liver transplantation. The initial immunosuppression of essentially all recipients was a calcineurin inhibitor-based regimen. Close, long-term follow-up of liver transplant recipients permits optimal management of liver allograft and native renal function and can lead to excellent long-term outcomes despite a calcineurin inhibitor-based immunosuppressive regimen. © 2013 John Wiley & Sons A/S.

Septic single-stage knee arthrodesis after failed total knee arthroplasty using a cemented coupled nail.

PubMed

Hawi, N; Kendoff, D; Citak, M; Gehrke, T; Haasper, C

2015-05-01

Knee arthrodesis is a potential salvage procedure for limb preservation after failure of total knee arthroplasty (TKA) due to infection. In this study, we evaluated the outcome of single-stage knee arthrodesis using an intramedullary cemented coupled nail without bone-on-bone fusion after failed and infected TKA with extensor mechanism deficiency. Between 2002 and 2012, 27 patients (ten female, 17 male; mean age 68.8 years; 52 to 87) were treated with septic single-stage exchange. Mean follow-up duration was 67.1months (24 to 143, n = 27) (minimum follow-up 24 months) and for patients with a minimum follow-up of five years 104.9 (65 to 143,; n = 13). A subjective patient evaluation (Short Form (SF)-36) was obtained, in addition to the Visual Analogue Scale (VAS). The mean VAS score was 1.44 (SD 1.48). At final follow-up, four patients had recurrent infections after arthrodesis (14.8%). Of these, three patients were treated with a one-stage arthrodesis nail exchange; one of the three patients had an aseptic loosening with a third single-stage exchange, and one patient underwent knee amputation for uncontrolled sepsis at 108 months. All patients, including the amputee, indicated that they would choose arthrodesis again. Data indicate that a single-stage knee arthrodesis offers an acceptable salvage procedure after failed and infected TKA. ©2015 The British Editorial Society of Bone & Joint Surgery.

The Efficacy of Bulbar Urethral Mobilization for Anastomotic Anterior Urethroplasty in a Case With Recurrent Anterior Urethral Stricture

PubMed Central

Fukui, Shinji; Aoki, Katsuya; Kaneko, Yoshiteru; Samma, Shoji; Fujimoto, Kiyohide

2014-01-01

A 2-month-old boy was diagnosed with febrile urinary tract infection. Voiding cystourethrography showed bulbar and anterior urethral strictures, and endoscopic internal urethrotomy was performed. He developed febrile urinary tract infection again and revealed the recurrence of the anterior urethral stricture. Consequently, endoscopic internal urethrotomy was performed 4 times. Because the anterior urethral stricture had not improved, he was referred to us. Anterior urethroplasty was performed when he was 5 years. After excision of the scarred portions of the urethra, the defect of the urethra was 20 mm. Transperineal bulbar urethral mobilization was performed, and a single-stage end-to-end anterior urethroplasty without tension could be performed simultaneously. PMID:26955558

The Efficacy of Bulbar Urethral Mobilization for Anastomotic Anterior Urethroplasty in a Case With Recurrent Anterior Urethral Stricture.

PubMed

Fukui, Shinji; Aoki, Katsuya; Kaneko, Yoshiteru; Samma, Shoji; Fujimoto, Kiyohide

2014-05-01

A 2-month-old boy was diagnosed with febrile urinary tract infection. Voiding cystourethrography showed bulbar and anterior urethral strictures, and endoscopic internal urethrotomy was performed. He developed febrile urinary tract infection again and revealed the recurrence of the anterior urethral stricture. Consequently, endoscopic internal urethrotomy was performed 4 times. Because the anterior urethral stricture had not improved, he was referred to us. Anterior urethroplasty was performed when he was 5 years. After excision of the scarred portions of the urethra, the defect of the urethra was 20 mm. Transperineal bulbar urethral mobilization was performed, and a single-stage end-to-end anterior urethroplasty without tension could be performed simultaneously.

Energy efficient engine high-pressure turbine component rig performance test report

NASA Technical Reports Server (NTRS)

Leach, K. P.

1983-01-01

A rig test of the cooled high-pressure turbine component for the Energy Efficient Engine was successfully completed. The principal objective of this test was to substantiate the turbine design point performance as well as determine off-design performance with the interaction of the secondary flow system. The measured efficiency of the cooled turbine component was 88.5 percent, which surpassed the rig design goal of 86.5 percent. The secondary flow system in the turbine performed according to the design intent. Characterization studies showed that secondary flow system performance is insensitive to flow and pressure variations. Overall, this test has demonstrated that a highly-loaded, transonic, single-stage turbine can achieve a high level of operating efficiency.

Statistical study of single and multiple pulse laser-induced damage in glasses.

PubMed

Gallais, L; Natoli, J; Amra, C

2002-12-16

Single and multiple pulse laser damage studies are performed in Suprasil silica and BK-7 borosilicate glasses. Experiments are made in the bulk of materials at 1.064microm with nanosecond pulses, using an accurate and reliable measurement system. By means of a statistical study on laser damage probabilities, we demonstrate that the same nano-precursors could be involved in the multiple shot and single shot damage process. A damage mechanism with two stages is then proposed to explain the results. Firstly, a pre-damage process, corresponding to material changes at a microscopic level, leads the precursor to a state that can induce a one-pulse damage. And secondly a final damage occurs, with a mechanism identical to the single shot case. For each material, a law is found to predict the precursor life-time. We can then deduce the long term life of optical elements in high-power laser systems submitted to multipulse irradiation.

Removal of pharmaceuticals in pre-denitrifying MBBR - Influence of organic substrate availability in single- and three-stage configurations.

PubMed

Polesel, Fabio; Torresi, Elena; Loreggian, Luca; Casas, Mònica Escolà; Christensson, Magnus; Bester, Kai; Plósz, Benedek Gy

2017-10-15

Due to the limited efficiency of conventional biological treatment, innovative solutions are being explored to improve the removal of trace organic chemicals in wastewater. Controlling biomass exposure to growth substrate represents an appealing option for process optimization, as substrate availability likely impacts microbial activity, hence organic trace chemical removal. This study investigated the elimination of pharmaceuticals in pre-denitrifying moving bed biofilm reactors (MBBRs), where biofilm exposure to different organic substrate loading and composition was controlled by reactor staging. A three-stage MBBR and a single-stage reference MBBR (with the same operating volume and filling ratio) were operated under continuous-flow conditions (18 months). Two sets of batch experiments (day 100 and 471) were performed to quantify and compare pharmaceutical removal and denitrification kinetics in the different MBBRs. Experimental results revealed the possible influence of retransformation (e.g., from conjugated metabolites) and enantioselectivity on the removal of selected pharmaceuticals. In the second set of experiments, specific trends in denitrification and biotransformation kinetics were observed, with highest and lowest rates/rate constants in the first (S1) and the last (S3) staged sub-reactors, respectively. These observations were confirmed by removal efficiency data obtained during continuous-flow operation, with limited removal (<10%) of recalcitrant pharmaceuticals and highest removal in S1 within the three-stage MBBR. Notably, biotransformation rate constants obtained for non-recalcitrant pharmaceuticals correlated with mean specific denitrification rates, maximum specific growth rates and observed growth yield values. Overall, these findings suggest that: (i) the long-term exposure to tiered substrate accessibility in the three-stage configuration shaped the denitrification and biotransformation capacity of biofilms, with significant reduction under substrate limitation; (ii) biotransformation of pharmaceuticals may have occurred as a result of cometabolism by heterotrophic denitrifying bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

Forward osmosis membrane modular configurations for osmotic dilution of seawater by forward osmosis and reverse osmosis hybrid system.

PubMed

Kim, Jung Eun; Phuntsho, Sherub; Ali, Syed Muztuza; Choi, Joon Young; Shon, Ho Kyong

2018-01-01

This study evaluates various options for full-scale modular configuration of forward osmosis (FO) process for osmotic dilution of seawater using wastewater for simultaneous desalination and water reuse through FO-reverse osmosis (RO) hybrid system. Empirical relationship obtained from one FO membrane element operation was used to simulate the operational performances of different FO module configurations. The main limiting criteria for module operation is to always maintain the feed pressure higher than the draw pressure throughout the housing module for safe operation without affecting membrane integrity. Experimental studies under the conditions tested in this study show that a single membrane housing cannot accommodate more than four elements as the draw pressure exceeds the feed pressure. This then indicates that a single stage housing with eight elements is not likely to be practical for safe FO operation. Hence, six different FO modular configurations were proposed and simulated. A two-stage FO configuration with multiple housings (in parallel) in the second stage using same or larger spacer thickness reduces draw pressure build-up as the draw flow rates are reduced to half in the second stage thereby allowing more than four elements in the second stage housing. The loss of feed pressure (pressure drop) and osmotic driving force in the second stage are compensated by operating under the pressure assisted osmosis (PAO) mode, which helps enhance permeate flux and maintains positive pressure differences between the feed and draw chamber. The PAO energy penalty is compensated by enhanced permeate throughput, reduced membrane area, and plant footprint. The contribution of FO/PAO to total energy consumption was not significant compared to post RO desalination (90%) indicating that the proposed two-stage FO modular configuration is one way of making the FO full-scale operation practical for FO-RO hybrid system. Copyright © 2017 Elsevier Ltd. All rights reserved.

A portable high-power diode laser-based single-stage ceramic tile grout sealing system

NASA Astrophysics Data System (ADS)

Lawrence, J.; Schmidt, M. J. J.; Li, L.; Edwards, R. E.; Gale, A. W.

2002-02-01

By means of a 60 W high-power diode laser (HPDL) and a specially developed grout material the void between adjoining ceramic tiles has been successfully sealed. A single-stage process has been developed which uses a crushed ceramic tile mix to act as a tough, inexpensive bulk substrate and a glazed enamel surface to provide an impervious surface glaze. The single-stage ceramic tile grout sealing process yielded seals produced in normal atmospheric conditions that displayed no discernible cracks and porosities. The single-stage grout is simple to formulate and easy to apply. Tiles were successfully sealed with power densities as low as 200 kW/ mm2 and at rates of up to 600 mm/ min. Bonding of the enamel to the crushed ceramic tile mix was identified as being primarily due to van der Waals forces and, on a very small scale, some of the crushed ceramic tile mix material dissolving into the glaze. In terms of mechanical, physical and chemical characteristics, the single-stage ceramic tile grout was found to be far superior to the conventional epoxy tile grout and, in many instances, matched and occasionally surpassed that of the ceramic tiles themselves. What is more, the development of a hand-held HPDL beam delivery unit and the related procedures necessary to lead to the commercialisation of the single-stage ceramic tile grout sealing process are presented. Further, an appraisal of the potential hazards associated with the use of the HPDL in an industrial environment and the solutions implemented to ensure that the system complies with the relevant safety standards are given.

Comparison of Clinicopathological Characteristics in the Patients with Cardiac Cancer with or without Esophagogastric Junctional Invasion: A Single-Center Retrospective Cohort Study

PubMed Central

Ito, Hiroaki; Inoue, Haruhiro; Odaka, Noriko; Satodate, Hitoshi; Suzuki, Michitaka; Mukai, Shumpei; Takehara, Yusuke; Omoto, Tomokatsu; Kudo, Shin-ei

2013-01-01

Background. This study addresses clinicopathological differences between patients with gastric cardia and subcardial cancer with and without esophagogastric junctional invasion. Methods. We performed a single-center, retrospective cohort study. We studied patients who underwent curative surgery for gastric cardia and subcardial cancers. Tumors centered in the proximal 5 cm of the stomach were classed into two types, according to whether they did (Ge) or did not (G) invade the esophagogastric junction. Results. A total of 80 patients were studied; 19 (73.1%) of 26 Ge tumors and 16 (29.6%) of 54 G tumors had lymph nodes metastases. Incidence of nodal metastasis in pT1 tumors was significantly higher in the Ge tumor group. No nodal metastasis in cervical lymph nodes was recognized. Only two patients with Ge tumors had mediastinal lymph node metastases. Incidence of perigastric lymph node metastasis was significantly higher in those with Ge tumors. Ge tumors tended to be staged as progressive disease using the esophageal cancer staging manual rather than the gastric cancer staging manual. Conclusion. Because there are some differences in clinicopathological characteristics, it is thought to be adequate to distinguish type Ge from type G tumor. PMID:23365732

Effects of size and thermophilic pre-hydrolysis of banana peel during anaerobic digestion, and biomethanation potential of key tropical fruit wastes.

PubMed

Odedina, Mary Jesuyemi; Charnnok, Boonya; Saritpongteeraka, Kanyarat; Chaiprapat, Sumate

2017-10-01

Methane production potential of tropical fruit wastes, namely lady-finger banana peel, rambutan waste and longan waste were compared using BMP assay and stoichiometric modified Buswell and Mueller equation. Methane yields based on volatile solid (VS) were in the order of ground banana peel, chopped banana peel, chopped longan waste, and chopped rambutan waste (330.6, 268.3, 234.6 and 193.2 mLCH 4 /gVS) that corresponded to their calculated biodegradability. In continuous operations of banana peel digestion at feed concentrations based on total solid (TS) 1-2%, mesophilic single stage digester run at 20-day hydraulic retention time (20-day HRT) failed at 2%TS, but successfully recovered at 1.5%TS. Pre-hydrolysis thermophilic reactor (4-d HRT) was placed as pre-treatment to mesophilic reactor (20-d HRT). Higher biogas (with an evolution of H 2 ) and energy yields were obtained and greater system stability was achieved over the single stage digestion, particularly at higher solid feedstock. The best performance of two stage digestion was 68.5% VS destruction and energy yield of 2510.9kJ/kgVS added at a feed concentration of 2%TS. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

PubMed

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

2016-01-01

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

SOS2 and ACP1 Loci Identified through Large-Scale Exome Chip Analysis Regulate Kidney Development and Function.

PubMed

Li, Man; Li, Yong; Weeks, Olivia; Mijatovic, Vladan; Teumer, Alexander; Huffman, Jennifer E; Tromp, Gerard; Fuchsberger, Christian; Gorski, Mathias; Lyytikäinen, Leo-Pekka; Nutile, Teresa; Sedaghat, Sanaz; Sorice, Rossella; Tin, Adrienne; Yang, Qiong; Ahluwalia, Tarunveer S; Arking, Dan E; Bihlmeyer, Nathan A; Böger, Carsten A; Carroll, Robert J; Chasman, Daniel I; Cornelis, Marilyn C; Dehghan, Abbas; Faul, Jessica D; Feitosa, Mary F; Gambaro, Giovanni; Gasparini, Paolo; Giulianini, Franco; Heid, Iris; Huang, Jinyan; Imboden, Medea; Jackson, Anne U; Jeff, Janina; Jhun, Min A; Katz, Ronit; Kifley, Annette; Kilpeläinen, Tuomas O; Kumar, Ashish; Laakso, Markku; Li-Gao, Ruifang; Lohman, Kurt; Lu, Yingchang; Mägi, Reedik; Malerba, Giovanni; Mihailov, Evelin; Mohlke, Karen L; Mook-Kanamori, Dennis O; Robino, Antonietta; Ruderfer, Douglas; Salvi, Erika; Schick, Ursula M; Schulz, Christina-Alexandra; Smith, Albert V; Smith, Jennifer A; Traglia, Michela; Yerges-Armstrong, Laura M; Zhao, Wei; Goodarzi, Mark O; Kraja, Aldi T; Liu, Chunyu; Wessel, Jennifer; Boerwinkle, Eric; Borecki, Ingrid B; Bork-Jensen, Jette; Bottinger, Erwin P; Braga, Daniele; Brandslund, Ivan; Brody, Jennifer A; Campbell, Archie; Carey, David J; Christensen, Cramer; Coresh, Josef; Crook, Errol; Curhan, Gary C; Cusi, Daniele; de Boer, Ian H; de Vries, Aiko P J; Denny, Joshua C; Devuyst, Olivier; Dreisbach, Albert W; Endlich, Karlhans; Esko, Tõnu; Franco, Oscar H; Fulop, Tibor; Gerhard, Glenn S; Glümer, Charlotte; Gottesman, Omri; Grarup, Niels; Gudnason, Vilmundur; Hansen, Torben; Harris, Tamara B; Hayward, Caroline; Hocking, Lynne; Hofman, Albert; Hu, Frank B; Husemoen, Lise Lotte N; Jackson, Rebecca D; Jørgensen, Torben; Jørgensen, Marit E; Kähönen, Mika; Kardia, Sharon L R; König, Wolfgang; Kooperberg, Charles; Kriebel, Jennifer; Launer, Lenore J; Lauritzen, Torsten; Lehtimäki, Terho; Levy, Daniel; Linksted, Pamela; Linneberg, Allan; Liu, Yongmei; Loos, Ruth J F; Lupo, Antonio; Meisinger, Christine; Melander, Olle; Metspalu, Andres; Mitchell, Paul; Nauck, Matthias; Nürnberg, Peter; Orho-Melander, Marju; Parsa, Afshin; Pedersen, Oluf; Peters, Annette; Peters, Ulrike; Polasek, Ozren; Porteous, David; Probst-Hensch, Nicole M; Psaty, Bruce M; Qi, Lu; Raitakari, Olli T; Reiner, Alex P; Rettig, Rainer; Ridker, Paul M; Rivadeneira, Fernando; Rossouw, Jacques E; Schmidt, Frank; Siscovick, David; Soranzo, Nicole; Strauch, Konstantin; Toniolo, Daniela; Turner, Stephen T; Uitterlinden, André G; Ulivi, Sheila; Velayutham, Dinesh; Völker, Uwe; Völzke, Henry; Waldenberger, Melanie; Wang, Jie Jin; Weir, David R; Witte, Daniel; Kuivaniemi, Helena; Fox, Caroline S; Franceschini, Nora; Goessling, Wolfram; Köttgen, Anna; Chu, Audrey Y

2017-03-01

Genome-wide association studies have identified >50 common variants associated with kidney function, but these variants do not fully explain the variation in eGFR. We performed a two-stage meta-analysis of associations between genotypes from the Illumina exome array and eGFR on the basis of serum creatinine (eGFRcrea) among participants of European ancestry from the CKDGen Consortium ( n Stage1 : 111,666; n Stage2 : 48,343). In single-variant analyses, we identified single nucleotide polymorphisms at seven new loci associated with eGFRcrea ( PPM1J , EDEM3, ACP1, SPEG, EYA4, CYP1A1 , and ATXN2L ; P Stage1 <3.7×10 -7 ), of which most were common and annotated as nonsynonymous variants. Gene-based analysis identified associations of functional rare variants in three genes with eGFRcrea, including a novel association with the SOS Ras/Rho guanine nucleotide exchange factor 2 gene, SOS2 ( P =5.4×10 -8 by sequence kernel association test). Experimental follow-up in zebrafish embryos revealed changes in glomerular gene expression and renal tubule morphology in the embryonic kidney of acp1- and sos2 -knockdowns. These developmental abnormalities associated with altered blood clearance rate and heightened prevalence of edema. This study expands the number of loci associated with kidney function and identifies novel genes with potential roles in kidney formation. Copyright © 2017 by the American Society of Nephrology.

Performance Evaluation of Staged Bosch Process for CO2 Reduction to Produce Life Support Consumables

NASA Technical Reports Server (NTRS)

Vilekar, Saurabh A.; Hawley, Kyle; Junaedi, Christian; Walsh, Dennis; Roychoudhury, Subir; Abney. Morgan B.; Mansell, James M.

2012-01-01

Utilizing carbon dioxide to produce water and hence oxygen is critical for sustained manned missions in space, and to support both NASA's cabin Atmosphere Revitalization System (ARS) and In-Situ Resource Utilization (ISRU) concepts. For long term missions beyond low Earth orbit, where resupply is significantly more difficult and costly, open loop ARS, like Sabatier, consume inputs such as hydrogen. The Bosch process, on the other hand, has the potential to achieve complete loop closure and is hence a preferred choice. However, current single stage Bosch reactor designs suffer from a large recycle penalty due to slow reaction rates and the inherent limitation in approaching thermodynamic equilibrium. Developmental efforts are seeking to improve upon the efficiency (hence reducing the recycle penalty) of current single stage Bosch reactors which employ traditional steel wool catalysts. Precision Combustion, Inc. (PCI), with support from NASA, has investigated the potential for utilizing catalysts supported over short-contact time Microlith substrates for the Bosch reaction to achieve faster reaction rates, higher conversions, and a reduced recycle flows. Proof-of-concept testing was accomplished for a staged Bosch process by splitting the chemistry in two separate reactors, first being the reverse water-gas-shift (RWGS) and the second being the carbon formation reactor (CFR) via hydrogenation and/or Boudouard. This paper presents the results from this feasibility study at various operating conditions. Additionally, results from two 70 hour durability tests for the RWGS reactor are discussed.

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

PubMed

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

2002-03-29

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

Reading Aloud: Discrete Stage(s) Redux

PubMed Central

Robidoux, Serje; Besner, Derek

2017-01-01

Interactive activation accounts of processing have had a broad and deep influence on cognitive psychology, particularly so in the context of computational accounts of reading aloud at the single word level. Here we address the issue of whether such a framework can simulate the joint effects of stimulus quality and word frequency (which have been shown to produce both additive and interactive effects depending on the context). We extend previous work on this question by considering an alternative implementation of a stimulus quality manipulation, and the role of interactive activation. Simulations with a version of the Dual Route Cascaded model (a model with interactive activation dynamics along the lexical route) demonstrate that the model is unable to simulate the entire pattern seen in human performance. We discuss how a hybrid interactive activation model that includes some context dependent staged processing could accommodate these data. PMID:28289395

Feminising genitoplasty: one-stage genital reconstruction in congenital adrenal hyperplasia: 30 years' experience.

PubMed

Roll, M F; Kneppo, C; Roth, H; Bettendorf, M; Waag, K-L; Holland-Cunz, S

2006-10-01

The study objective is to evaluate the results of our surgical technique for children with congenital adrenal hyperplasia and ambiguous genitalia at the University Hospital of Heidelberg, Department of Paediatric Surgery. The records of 19 patients with congenital adrenal hyperplasia treated between 1972 and 2004 were reviewed with respect to age at surgery, operative procedures and outcome. We describe the recession clitoroplasty technique currently used in our hospital and highlight the importance of short and long-term follow-up results with respect to appearance, position and size of the clitoris and quality of the vagina. One-stage recession clitoroplasty and vaginoplasty gives very satisfactory cosmetic and functional results, with few complications and a reduced need for secondary surgical interventions. The results of this study support the assumption that total correction can be achieved through a single-stage operation, performed in infancy.

Proximal hypospadias: A persistent challenge. Single institution outcome analysis of three surgical techniques over a 10-year period.

PubMed

Pippi Salle, J L; Sayed, S; Salle, A; Bagli, D; Farhat, W; Koyle, M; Lorenzo, A J

2016-02-01

The optimal treatment of proximal hypospadias remains controversial. Several techniques have been described, but the best approach remains unsettled. To evaluate and compare the complication rates of proximal hypospadias with and without ventral curvature (VC), according to three different surgical techniques: tubularized incised plate (TIP) uretroplasty, dorsal inlay graft TIP (DIG), and staged preputial repair (SR). It was hypothesized that SR performs better than TIP and DIG for proximal hypospadias. Single-center, retrospective chart review of all patients with primary proximal hypospadias reconstructed between 2003 and 2013. The DIG was selectively employed in cases with narrow urethral plate (UP) and deficient spongiosum. Extensive urethral plate (UP) mobilization (UPM), dorsal plication (DP) and/or deep transverse incisions of tunica albuginea (DTITA) were selectively performed when attempting to spare transecting the UP. Division of UP and SR was favored in cases with severe VC (>50°), which was often concurrently managed with DTITA if intrinsic curvature was present. For SR, tubularization of the graft was performed 6 months later. A total of 140 patients were included. Tubularized incised plate (TIP), DIG, and SR techniques were performed in 57, 23, and 60 patients, respectively. The TIP and DIG techniques achieved similar success rates, although DIG was performed in cases of narrow and spongiosum-deficient plates. Reoperation rates with TIP and DIG techniques was 52.6% and 52.1% (NS). Urethro-cutaneous fistulas were seen in 31.5% and 13% of TIP and DIG techniques, respectively. Staged repair accomplished better results than both TIP and DIG techniques, despite being performed in the most unfavorable cases (reoperation rate 28%). After technical modifications, the DIG technique achieved similar outcomes of SR. Proximal hypospadias remains challenging, regardless of the technique utilized for its repair. Urethro-cutaneous fistulas were more commonly seen after long TIP repairs. Approximately half of the patients undergoing long TIP and DIG procedures needed re-intervention, although the percentage decreased significantly with late modifications in the DIG group. Recurrence of VC after TIP and DIG techniques seemed to be a significant and under-reported complication. Staged repairs, despite being performed for the most severe cases, resulted in overall better outcomes. Copyright © 2015 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

Discriminating ability of Cirrus and RTVue optical coherence tomography in different stages of glaucoma

PubMed Central

Mittal, Deepti; Dubey, Suneeta; Gandhi, Monica; Pegu, Julie; Bhoot, Madhu; Gupta, Yadunandan Prasad

2018-01-01

Purpose: The aim of this study is to determine which parameter of Cirrus and RTVue optical coherence tomography (OCT) has the highest ability to discriminate between early, moderate, and advanced glaucoma. Simultaneously, to compare the performance of the two OCT devices in terms of their ability to differentiate the three stages of glaucoma. Further, to analyze the macular parameters of both devices and compare them with the conventional retinal nerve fiber layer (RNFL) parameters. Methods: One hundred and twenty eyes (30 healthy and 90 glaucomatous [30 mild, 30 moderate, and 30 advanced glaucoma]) of 65 participants (15 healthy, 50 glaucomatous [15 mild, 15 moderate, and 20 advanced glaucoma]) underwent Cirrus and RTVue OCT scanning on a single visit. Results: Average RNFL thickness and superior RNFL thickness of both the devices and inferior (ganglion cell complex [GCC] of RTVue device best differentiated normals from all stage glaucomatous eyes (P > 0.05). Cirrus average RNFL thickness and superior RNFL thickness performed better than other parameters (P < 0.05) in differentiating early glaucoma from moderate and advanced. In differentiating advanced from early and moderate glaucoma, RTVue average, superior, and inferior RNFL thickness and inferior GCC parameters had the highest discriminating ability (P < 0.05). Conclusion: Overall, average RNFL thickness had the highest ability to distinguish different stages of the disease. No significant difference was found between RTVue and Cirrus OCT device in different severity levels. No significant difference was observed between RNFL and macular parameters in different stages of glaucoma. PMID:29676314

Two-stage distraction lengthening of the forearm.

PubMed

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

2013-01-01

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

Discriminating ability of Cirrus and RTVue optical coherence tomography in different stages of glaucoma.

PubMed

Mittal, Deepti; Dubey, Suneeta; Gandhi, Monica; Pegu, Julie; Bhoot, Madhu; Gupta, Yadunandan Prasad

2018-05-01

The aim of this study is to determine which parameter of Cirrus and RTVue optical coherence tomography (OCT) has the highest ability to discriminate between early, moderate, and advanced glaucoma. Simultaneously, to compare the performance of the two OCT devices in terms of their ability to differentiate the three stages of glaucoma. Further, to analyze the macular parameters of both devices and compare them with the conventional retinal nerve fiber layer (RNFL) parameters. One hundred and twenty eyes (30 healthy and 90 glaucomatous [30 mild, 30 moderate, and 30 advanced glaucoma]) of 65 participants (15 healthy, 50 glaucomatous [15 mild, 15 moderate, and 20 advanced glaucoma]) underwent Cirrus and RTVue OCT scanning on a single visit. Average RNFL thickness and superior RNFL thickness of both the devices and inferior (ganglion cell complex [GCC] of RTVue device best differentiated normals from all stage glaucomatous eyes (P > 0.05). Cirrus average RNFL thickness and superior RNFL thickness performed better than other parameters (P < 0.05) in differentiating early glaucoma from moderate and advanced. In differentiating advanced from early and moderate glaucoma, RTVue average, superior, and inferior RNFL thickness and inferior GCC parameters had the highest discriminating ability (P < 0.05). Overall, average RNFL thickness had the highest ability to distinguish different stages of the disease. No significant difference was found between RTVue and Cirrus OCT device in different severity levels. No significant difference was observed between RNFL and macular parameters in different stages of glaucoma.

Measurement of Liver Stiffness Using Shear Wave Elastography in a Rat Model: Factors Impacting Stiffness Measurement with Multiple- and Single-Tracking-Location Techniques.

PubMed

Langdon, Jonathan H; Elegbe, Etana; Gonzalez, Raul S; Osapoetra, Laurentius; Ford, Tristan; McAleavey, Stephen A

2017-11-01

The clinical use of elastography for monitoring fibrosis progression is challenged by the subtle changes in liver stiffness associated with early-stage fibrosis and the comparatively large variance in stiffness estimates provided by elastography. Single-tracking-location (STL) shear wave elasticity imaging (SWEI) is an ultrasound elastography technique previously found to provide improved estimate precision compared with multiple-tracking-location (MTL) SWEI. Because of the improved precision, it is reasonable to expect that STL-SWEI would provide improved ability to differentiate liver fibrosis stage compared with MTL-SWEI. However, this expectation has not been previously challenged rigorously. In this work, the performance of STL- and MTL-SWEI in the setting of a rat model of liver fibrosis is characterized, and the advantages of STL-SWEI in staging fibrosis are explored. The purpose of this study was to determine what advantages, if any, arise from using STL-SWEI instead of MTL-SWEI in the characterization of fibrotic liver. Thus, the ability of STL-SWEI to differentiate livers at various METAVIR fibrosis scores, for ex vivo postmortem measurements, is explored. In addition, we examined the effect of the common confounding factor of fluid versus solid boundary conditions in SWEI experiments. Sprague-Dawley rats were treated with carbon tetrachloride over several weeks to produce liver disease of varying severity. STL and MTL stiffness measurements were performed ex vivo and compared with the METAVIR scores from histological analysis and the duration of treatment. A strong association was observed between liver stiffness and weeks of treatment with the liver toxin carbon tetrachloride. Direct comparison of STL- and MTL-SWEI measurements revealed no significant difference in ability to differentiate fibrosis stages based on SWEI mean values. However, image interquartile range was greatly improved in the case of STL-SWEI, compared with MTL-SWEI, at small beam spacing. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Single-Stage Ear Reconstruction and Hearing Restoration Using Polyethylene Implant and Implantable Hearing Devices.

PubMed

Hempel, John Martin

2015-12-01

The use of porous polyethylene in reconstructive surgery of the auricle is becoming increasingly accepted. This is a single-stage procedure providing pleasing cosmetic rehabilitation. Further advantages are the possibility of early implantation and the lack of complications caused by harvesting costal cartilage. Additional hearing restoration using middle ear implants allows functional rehabilitation at an early stage. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Standing balance in individuals with Parkinson's disease during single and dual-task conditions.

PubMed

Fernandes, Ângela; Coelho, Tiago; Vitória, Ana; Ferreira, Augusto; Santos, Rubim; Rocha, Nuno; Fernandes, Lia; Tavares, João Manuel R S

2015-09-01

This study aimed to examine the differences in standing balance between individuals with Parkinson's disease (PD) and subjects without PD (control group), under single and dual-task conditions. A cross-sectional study was designed using a non-probabilistic sample of 110 individuals (50 participants with PD and 60 controls) aged 50 years old and over. The individuals with PD were in the early or middle stages of the disease (characterized by Hoehn and Yahr as stages 1-3). The standing balance was assessed by measuring the centre of pressure (CoP) displacement in single-task (eyes-open/eyes-closed) and dual-task (while performing two different verbal fluency tasks). No significant differences were found between the groups regarding sociodemographic variables. In general, the standing balance of the individuals with PD was worse than the controls, as the CoP displacement across tasks was significantly higher for the individuals with PD (p<0.01), both in anteroposterior and mediolateral directions. Moreover, there were significant differences in the CoP displacement based parameters between the conditions, mainly between the eyes-open condition and the remaining conditions. However, there was no significant interaction found between group and condition, which suggests that changes in the CoP displacement between tasks were not influenced by having PD. In conclusion, this study shows that, although individuals with PD had a worse overall standing balance than individuals without the disease, the impact of performing an additional task on the CoP displacement is similar for both groups. Copyright © 2015 Elsevier B.V. All rights reserved.

What is the most accurate lymph node staging method for perihilar cholangiocarcinoma? Comparison of UICC/AJCC pN stage, number of metastatic lymph nodes, lymph node ratio, and log odds of metastatic lymph nodes.

PubMed

Conci, S; Ruzzenente, A; Sandri, M; Bertuzzo, F; Campagnaro, T; Bagante, F; Capelli, P; D'Onofrio, M; Piccino, M; Dorna, A E; Pedrazzani, C; Iacono, C; Guglielmi, A

2017-04-01

We compared the prognostic performance of the International Union Against Cancer/American Joint Committee on Cancer (UICC/AJCC) 7th edition pN stage, number of metastatic LNs (MLNs), LN ratio (LNR), and log odds of MLNs (LODDS) in patients with perihilar cholangiocarcinoma (PCC) undergoing curative surgery in order to identify the best LN staging method. Ninety-nine patients who underwent surgery with curative intent for PCC in a single tertiary hepatobiliary referral center were included in the study. Two approaches were used to evaluate and compare the predictive power of the different LN staging methods: one based on the estimation of variable importance with prediction error rate and the other based on the calculation of the receiver operating characteristic (ROC) curve. LN dissection was performed in 92 (92.9%) patients; 49 were UICC/AJCC pN0 (49.5%), 33 pN1 (33.3%), and 10 pN2 (10.1%). The median number of LNs retrieved was 8. The prediction error rate ranged from 42.7% for LODDS to 47.1% for UICC/AJCC pN stage. Moreover, LODDS was the variable with the highest area under the ROC curve (AUC) for prediction of 3-year survival (AUC = 0.71), followed by LNR (AUC = 0.60), number of MLNs (AUC = 0.59), and UICC/AJCC pN stage (AUC = 0.54). The number of MLNs, LNR, and LODDS appear to better predict survival than the UICC/AJCC pN stage in patients undergoing curative surgery for PCC. Moreover, LODDS seems to be the most accurate and predictive LN staging method. Copyright © 2017 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.

Energy efficient engine component development and integration program

NASA Technical Reports Server (NTRS)

1982-01-01

The objective of the Energy Efficient Engine Component Development and Integration program is to develop, evaluate, and demonstrate the technology for achieving lower installed fuel consumption and lower operating costs in future commercial turbofan engines. Minimum goals have been set for a 12 percent reduction in thrust specific fuel consumption (TSFC), 5 percent reduction in direct operating cost (DOC), and 50 percent reduction in performance degradation for the Energy Efficient Engine (flight propulsion system) relative to the JT9D-7A reference engine. The Energy Efficienct Engine features a twin spool, direct drive, mixed flow exhaust configuration, utilizing an integrated engine nacelle structure. A short, stiff, high rotor and a single stage high pressure turbine are among the major enhancements in providing for both performance retention and major reductions in maintenance and direct operating costs. Improved clearance control in the high pressure compressor and turbines, and advanced single crystal materials in turbine blades and vanes are among the major features providing performance improvement. Highlights of work accomplished and programs modifications and deletions are presented.

Crystal Growth and Dissolution of Methylammonium Lead Iodide Perovskite in Sequential Deposition: Correlation between Morphology Evolution and Photovoltaic Performance.

PubMed

Hsieh, Tsung-Yu; Huang, Chi-Kai; Su, Tzu-Sen; Hong, Cheng-You; Wei, Tzu-Chien

2017-03-15

Crystal morphology and structure are important for improving the organic-inorganic lead halide perovskite semiconductor property in optoelectronic, electronic, and photovoltaic devices. In particular, crystal growth and dissolution are two major phenomena in determining the morphology of methylammonium lead iodide perovskite in the sequential deposition method for fabricating a perovskite solar cell. In this report, the effect of immersion time in the second step, i.e., methlyammonium iodide immersion in the morphological, structural, optical, and photovoltaic evolution, is extensively investigated. Supported by experimental evidence, a five-staged, time-dependent evolution of the morphology of methylammonium lead iodide perovskite crystals is established and is well connected to the photovoltaic performance. This result is beneficial for engineering optimal time for methylammonium iodide immersion and converging the solar cell performance in the sequential deposition route. Meanwhile, our result suggests that large, well-faceted methylammonium lead iodide perovskite single crystal may be incubated by solution process. This offers a low cost route for synthesizing perovskite single crystal.

In situ fatigue loading stage inside scanning electron microscope

NASA Technical Reports Server (NTRS)

Telesman, Jack; Kantzos, Peter; Brewer, David

1988-01-01

A fatigue loading stage inside a scanning electron microscopy (SEM) was developed. The stage allows dynamic and static high-magnification and high-resolution viewing of the fatigue crack initiation and crack propagation processes. The loading stage is controlled by a closed-loop servohydraulic system. Maximum load is 1000 lb (4450 N) with test frequencies ranging up to 30 Hz. The stage accommodates specimens up to 2 inches (50 mm) in length and tolerates substantial specimen translation to view the propagating crack. At room temperature, acceptable working resolution is obtainable for magnifications ranging up to 10,000X. The system is equipped with a high-temperature setup designed for temperatures up to 2000 F (1100 C). The signal can be videotaped for further analysis of the pertinent fatigue damage mechanisms. The design allows for quick and easy interchange and conversion of the SEM from a loading stage configuration to its normal operational configuration and vice versa. Tests are performed entirely in the in-situ mode. In contrast to other designs, the NASA design has greatly extended the life of the loading stage by not exposing the bellows to cyclic loading. The loading stage was used to investigate the fatigue crack growth mechanisms in the (100)-oriented PWA 1480 single-crystal, nickel-based supperalloy. The high-magnification observations revealed the details of the crack growth processes.

Comparison of a single-channel EEG sleep study to polysomnography

PubMed Central

Lucey, Brendan P.; McLeland, Jennifer S.; Toedebusch, Cristina D.; Boyd, Jill; Morris, John C.; Landsness, Eric C.; Yamada, Kelvin; Holtzman, David M.

2016-01-01

Summary An accurate home sleep study to assess electroencephalography (EEG)-based sleep stages and EEG power would be advantageous for both clinical and research purposes, such as for longitudinal studies measuring changes in sleep stages over time. The purpose of this study was to compare sleep scoring of a single-channel EEG recorded simultaneously on the forehead against attended polysomnography. Participants were recruited from both a clinical sleep center and a longitudinal research study investigating cognitively-normal aging and Alzheimer's disease. Analysis for overall epoch-by-epoch agreement found strong and substantial agreement between the single-channel EEG compared to polysomnography (kappa=0.67). Slow wave activity in the frontal regions was also similar when comparing the single-channel EEG device to polysomnography. As expected, stage N1 showed poor agreement (sensitivity 0.2) due to lack of occipital electrodes. Other sleep parameters such as sleep latency and REM onset latency had decreased agreement. Participants with disrupted sleep consolidation, such as from obstructive sleep apnea, also had poor agreement. We suspect that disagreement in sleep parameters between the single-channel EEG and polysomnography is partially due to altered waveform morphology and/or poorer signal quality in the single-channel derivation. Our results show that single-channel EEG provides comparable results to polysomnography in assessing REM, combined stages N2 and N3 sleep, and several other parameters including frontal slow wave activity. The data establish that single-channel EEG can be a useful research tool. PMID:27252090

Linguistic Knowledge at Early Stage I; Evidence from Successive Single Word Utterances. Papers and Reports on Child Language Development, No. 12.

ERIC Educational Resources Information Center

Horgan, Dianne

A study was conducted to determine whether the child expresses linguistic knowledge during the single-word period. The order of mention in 65 sets of successive single-word utterances from five children at Stage 1, two to four years old, were analyzed. To elicit speech, the children were shown line drawings representing such situations as animate…

A novel, fast and efficient single-sensor automatic sleep-stage classification based on complementary cross-frequency coupling estimates.

PubMed

Dimitriadis, Stavros I; Salis, Christos; Linden, David

2018-04-01

Limitations of the manual scoring of polysomnograms, which include data from electroencephalogram (EEG), electro-oculogram (EOG), electrocardiogram (ECG) and electromyogram (EMG) channels have long been recognized. Manual staging is resource intensive and time consuming, and thus considerable effort must be spent to ensure inter-rater reliability. As a result, there is a great interest in techniques based on signal processing and machine learning for a completely Automatic Sleep Stage Classification (ASSC). In this paper, we present a single-EEG-sensor ASSC technique based on the dynamic reconfiguration of different aspects of cross-frequency coupling (CFC) estimated between predefined frequency pairs over 5 s epoch lengths. The proposed analytic scheme is demonstrated using the PhysioNet Sleep European Data Format (EDF) Database with repeat recordings from 20 healthy young adults. We validate our methodology in a second sleep dataset. We achieved very high classification sensitivity, specificity and accuracy of 96.2 ± 2.2%, 94.2 ± 2.3%, and 94.4 ± 2.2% across 20 folds, respectively, and also a high mean F1 score (92%, range 90-94%) when a multi-class Naive Bayes classifier was applied. High classification performance has been achieved also in the second sleep dataset. Our method outperformed the accuracy of previous studies not only on different datasets but also on the same database. Single-sensor ASSC makes the entire methodology appropriate for longitudinal monitoring using wearable EEG in real-world and laboratory-oriented environments. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

78 FR 4138 - Notice of Intent To Grant Co-Exclusive Licenses

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-18

... brine solution.//Patent Application Serial No. 13/426294: Process and apparatus for the selective dimerization of terpenes and alpha-olefin oligomers with a single-stage reactor and a single-stage fractionation system.//Patent Application Serial No. 13/426347: Process and apparatus for the selective...

A progressive 5-week exercise therapy program leads to significant improvement in knee function early after anterior cruciate ligament injury.

PubMed

Eitzen, Ingrid; Moksnes, Håvard; Snyder-Mackler, Lynn; Risberg, May Arna

2010-11-01

Prospective cohort study without a control group. Firstly, to present our 5-week progressive exercise therapy program in the early stage after anterior cruciate ligament (ACL) injury. Secondly, to evaluate changes in knee function after completion of the program for patients with ACL injury in general and also when classified as potential copers or noncopers, and, finally, to examine potential adverse events. Few studies concerning early-stage ACL rehabilitation protocols exist. Consequently, little is known about the tolerance for, and outcomes from, short-term exercise therapy programs in the early stage after injury. One-hundred patients were included in a 5-week progressive exercise therapy program, within 3 months after injury. Knee function before and after completion of the program was evaluated from isokinetic quadriceps and hamstrings muscle strength tests, 4 single-leg hop tests, 2 different self-assessment questionnaires, and a global rating of knee function. A 2-way mixed-model analysis of variance was conducted to evaluate changes from pretest to posttest for the limb symmetry index for muscle strength and single-leg hop tests, and the change in scores for the patient-reported questionnaires. In addition, absolute values and the standardized response mean for muscle strength and single-leg hop tests were calculated at pretest and posttest for the injured and uninjured limb. Adverse events during the 5-week period were recorded. The progressive 5-week exercise therapy program led to significant improvements (P<.05) in knee function from pretest to posttest both for patients classified as potential copers and noncopers. Standardized response mean values for changes in muscle strength and single-leg hop performance from pretest to posttest for the injured limb were moderate to strong (0.49-0.84), indicating the observed improvements to be clinically relevant. Adverse events occurred in 3.9% of the patients. Short-term progressive exercise therapy programs are well tolerated and should be incorporated in early-stage ACL rehabilitation, either to improve knee function before ACL reconstruction or as a first step in further nonoperative management. Therapy, level 2b.

The efficacy of single-stage open intramedullary nailing of neglected femur fractures.

PubMed

Boopalan, P R J V C; Sait, Azad; Jepegnanam, Thilak Samuel; Matthai, Thomas; Varghese, Viju Daniel

2014-02-01

Neglected femur fractures are not rare in the developing world. Treatment options include single-stage open reduction and intramedullary nailing, or open release, skeletal traction, and then second-stage open intramedullary nailing, with bone grafting. Single-stage procedures have the potential advantage of avoiding neurovascular complications secondary to acute lengthening, but they require a second operation, with potentially increased resource use and infection risk. We sought to determine the (1) likelihood of union, (2) complications and reoperations, and (3) functional results with single-stage open intramedullary nailing without bone grafting in patients with neglected femur fractures. Between January 2003 and December 2007, 17 consecutive patients presented to our practice with neglected femoral shaft fractures. All were treated with single-stage nailing without bone grafting. There were 15 men and two women with a median age of 27 years. The average time from fracture to treatment was 13 weeks (range, 4-44 weeks). Eleven patients underwent open nailing with interlocked nails and six were treated with cloverleaf Kuntscher nails. Patients were followed for a minimum of 6 months (mean, 33 months; range, 6-72 months). The mean preoperative ROM of the knee was 28° (range, 10°-150°) and femoral length discrepancy was 3.1 cm (range, 1-5 cm). All fractures united and the mean time to union was 16 weeks (range, 7-32 weeks). There were no neurologic complications secondary to acute lengthening. The mean postoperative ROM of the knee was 130° (range, 60°-150°). All patients were able to return to preinjury work. Sixteen patients regained their original femoral length. One-stage open intramedullary nailing of neglected femoral diaphyseal fractures without bone grafting was safe and effective, and obviated the need for a two-stage approach. Although the findings need to be replicated in larger numbers of patients, we believe this technique may be useful in treating patients with this injury, and may offer advantages in resource-constrained environments.

Proverb and idiom comprehension in Alzheimer disease.

PubMed

Kempler, D; Van Lancker, D; Read, S

1988-01-01

Twenty-nine patients diagnosed with Probable Alzheimer Disease were administered tests of word, familiar phrases (idioms and proverbs), and novel phrase comprehension. From the early stage of the disease, patients performed worse at understanding familiar phrases than single words or novel phrases. The results uphold common observations that AD patients have difficulty interpreting abstract meanings. Cognitive variables responsible for poor idiom/proverb comprehension and the clinical implications of this new protocol are discussed.

The Modeling, Simulation and Comparison of Interconnection Networks for Parallel Processing.

DTIC Science & Technology

1987-12-01

performs better at a lower hardware cost than do the single stage cube and mesh networks. As a result, the designer of a paralll pro- cessing system is...attempted, and in most cases succeeded, in designing and implementing faster. more powerful systems. Due to design innovations and technological advances...largely to the computational complexity of the algorithms executed. In the von Neumann machine, instructions must be executed in a sequential manner. Design

Interleukin-10 gene polymorphisms are associated with Behcet's disease but not with Vogt-Koyanagi-Harada syndrome in the Chinese Han population.

PubMed

Hu, Jianmin; Hou, Shengping; Zhu, Xueping; Fang, Jing; Zhou, Yan; Liu, Yunjia; Bai, Lin; Kijlstra, Aize; Yang, Peizeng

2015-01-01

This study aimed to investigate the association of interleukin (IL)-10 gene polymorphisms with Behcet's disease (BD) and Vogt-Koyanagi-Harada (VKH) syndrome in the Chinese Han population. A two-stage association study was performed on 718 BD patients, 300 VKH patients, and 1,753 controls. Genotyping of the IL-10 gene was performed for six single nucleotide polymorphisms (SNPs), including rs1800871, rs1800872, rs1800896, rs3021094, rs3790622, and rs1554286 using PCR-restricted fragment length polymorphism or TaqMan SNP assays. Real-time PCR was performed to test the IL-10 mRNA expression of the associated polymorphisms. The first-stage result showed significantly increased frequencies of the rs1800871 T allele, rs1800872 A allele, and rs1554286 T allele in BD patients compared with controls (Pcorrected (Pcorr)=1.82×10(-5), OR=1.837; Pcorr=6.1×10(-5), OR=1.780; Pcorr=3.15×10(-5), OR=1.794, respectively). There was no association of the tested six SNPs with VKH syndrome. A second-stage study was therefore performed in BD patients to validate the result of the first stage, showing a significantly increased frequency of the rs1800871 T allele (Second stage, Pcorr=5.59×10(-5), OR=1.493; Combined data, Pcorr=3.65×10(-11), OR=1.632). Compared to the controls, an increased frequency of the rs1800871 T allele was observed in BD patients with extraocular findings, including genital ulcers, skin lesions, and a positive pathergy test. No difference was found among the mRNA expressions of IL-10 in the peripheral blood mononuclear cells (PBMCs) of controls with different genotypes of rs1800871 after stimulation of lipopolysaccharide (LPS) or anti-CD3/CD28 antibodies. The findings showed that IL-10 is a risk gene for BD but not for VKH syndrome.

Investigation of the effect of pilot burner on lean blow out performance of a staged injector

NASA Astrophysics Data System (ADS)

Yang, Jinhu; Zhang, Kaiyu; Liu, Cunxi; Ruan, Changlong; Liu, Fuqiang; Xu, Gang

2014-12-01

The staged injector has exhibited great potential to achieve low emissions and is becoming the preferable choice of many civil airplanes. Moreover, it is promising to employ this injector design in military engine, which requires most of the combustion air enters the combustor through injector to reduce smoke emission. However, lean staged injector is prone to combustion instability and extinction in low load operation, so techniques for broadening its stable operation ranges are crucial for its application in real engine. In this work, the LBO performance of a staged injector is assessed and analyzed on a single sector test section. The experiment was done in atmospheric environment with optical access. Kerosene-PLIF technique was used to visualize the spray distribution and common camera was used to record the flame patterns. Emphasis is put on the influence of pilot burner on LBO performance. The fuel to air ratios at LBO of six injectors with different pilot swirler vane angle were evaluated and the obtained LBO data was converted into data at idle condition. Results show that the increase of pilot swirler vane angle could promote the air assisted atomization, which in turn improves the LBO performance slightly. Flame patterns typical in the process of LBO are analyzed and attempts are made to find out the main factors which govern the extinction process with the assistance of spray distribution and numerical flow field results. It can be learned that the flame patterns are mainly influenced by structure of the flow field just behind the pilot burner when the fuel mass flow rate is high; with the reduction of fuel, atomization quality become more and more important and is the main contributing factor of LBO. In the end of the paper, conclusions are drawn and suggestions are made for the optimization of the present staged injector.

Shortest path problem on a grid network with unordered intermediate points

NASA Astrophysics Data System (ADS)

Saw, Veekeong; Rahman, Amirah; Eng Ong, Wen

2017-10-01

We consider a shortest path problem with single cost factor on a grid network with unordered intermediate points. A two stage heuristic algorithm is proposed to find a feasible solution path within a reasonable amount of time. To evaluate the performance of the proposed algorithm, computational experiments are performed on grid maps of varying size and number of intermediate points. Preliminary results for the problem are reported. Numerical comparisons against brute forcing show that the proposed algorithm consistently yields solutions that are within 10% of the optimal solution and uses significantly less computation time.

Validation of the CPS+EG and Neo-Bioscore staging systems after preoperative systemic therapy for breast cancer in a single center in China.

PubMed

Xu, Ling; Duan, Xuening; Zhou, Bin; Liu, Yinhua; Ye, Jingming; Liu, Zhaorui; Ma, Chao; Zhang, Hong; Zhang, Shuang; Zhang, Lanbo; Zhao, Jianxin; Cheng, Yuanjia

2018-04-17

Prognostic assessment after preoperative systemic therapy (PST) plays a vital role in determining treatment in breast cancer patients. Many researchers have sought to develop a system to quantitate residual tumor and its correlation with prognosis after PST. This retrospective study validated the CPS + EG staging system and Neo-Bioscore in a single center in China. Data from patients with non-metastatic primary breast cancer who were treated with PST and surgery from Jan. 2008 to Dec. 2014 at the Breast Disease Center of Peking University First Hospital, China, were reviewed. DFS, DSS and OS were calculated using the K-M curve and AUC. Multivariate analysis was used for a Cox proportional hazards model. All calculations were performed with SAS 9.4. A total of 403 patients were enrolled in this study. The median follow-up period was 45 (range 11-107) months. The five-year DFS, DSS and OS rates were 86.4%, 91.2% and 90.5%, respectively. The CS, PS, CPS + EG staging system and Neo-Bioscore stratified patients according to DFS, DSS, and OS after PST, with all P values < 0.0001. The CPS + EG staging system and Neo-Bioscore stratified prognosis after PST better than CS. HER2-positive patients without trastuzumab treatment had obviously worse DFS and OS than other subgroups with different HER2 statuses that scored a 3 in the Neo-Bioscore system. The CPS + EG staging system and Neo-Bioscore can improve prognostic prediction in non-pCR breast cancer patients after PST and, provided unfavorable prognostic factors such as insufficient treatment are incorporated, will have broader clinical applicability. Copyright © 2018 Elsevier Ltd. All rights reserved.

Simultaneous above and below approach to giant pituitary adenomas: surgical strategies and long-term follow-up

PubMed Central

D’Ambrosio, Anthony L.; Grobelny, Bartosz T.; Freda, Pamela U.; Wardlaw, Sharon; Bruce, Jeffrey N.

2012-01-01

Introduction Giant pituitary adenomas of excessive size, fibrous consistency or unfavorable geometric configuration may be unresectable through conventional operative approaches. We present our select case series for operative resection and long-term follow-up for these unusual tumors, employing both a staged procedure and a combined transsphenoidal-transcranial above and below approach. Method A retrospective chart review was performed on patients operated via the staged, and combined approaches by the senior author (J.N·B.). Pre-operative characteristics and postoperative outcomes were reviewed. A detailed description of the operative technique and perioperative management is provided. Results Between 1993 and 1996, two patients harboring giant pituitary adenomas underwent an intentionally staged resection, and between 1997 and 2006, nine patients harboring giant pituitary adenomas underwent surgery via a single-stage above and below approach. Nine patients (82%) presented with non-secreting adenomas and two patients (18%) presented with prolactinomas refractory to medical management. Gross total resection was achieved in six patients (55%), near total resection in 1 (9%), and subtotal removal in 4 (36%). Seven patients (64%) experienced visual improvement postoperatively and no major complications occurred. Long-term follow-up averaged 51.6 months. Panhypopituitarism was observed in four patients, partial hypopituitarism in four, persistent DI in two, and persistent SIADH in one. Conclusions The addition of a transcranial component to the transsphenoidal approach offers additional visualization of critical neurovascular structures during giant pituitary adenoma resection. Complications rates are similar to other series in which complex pituitary adenomas are resected by other means. The above and below approach is both safe and effective and the immediate and long-term advantages of a single-stage approach justify its utility in this select group of patients. PMID:19242807

Efficacy of Cyclooctadepsipeptides and Aminophenylamidines against Larval, Immature and Mature Adult Stages of a Parasitologically Characterized Trichurosis Model in Mice

PubMed Central

Kulke, Daniel; Krücken, Jürgen; Harder, Achim; von Samson-Himmelstjerna, Georg

2014-01-01

Background The genus Trichuris includes parasites of major relevance in veterinary and human medicine. Despite serious economic losses and enormous impact on public health, treatment options against whipworms are very limited. Additionally, there is an obvious lack of appropriately characterized experimental infection models. Therefore, a detailed parasitological characterization of a Trichuris muris isolate was performed in C57BL/10 mice. Subsequently, the in vivo efficacies of the aminophenylamidines amidantel, deacylated amidantel (dAMD) and tribendimidine as well as the cyclooctadepsipeptides emodepside and in particular PF1022A were analyzed. This was performed using various administration routes and treatment schemes targeting histotropic and further developed larval as well as immature and mature adult stages. Methodology/Principal Findings Duration of prepatent period, time-dependent localization of larvae during period of prepatency as well as the duration of patency of the infection were determined before drugs were tested in the characterized trichurosis model. Amidantel showed no effect against mature adult T. muris. Tribendimidine showed significantly higher potency than dAMD after oral treatments (ED50 values of 6.5 vs. 15.1 mg/kg). However, the opposite was found for intraperitoneal treatments (ED50 values of 15.3 vs. 8.3 mg/kg). When emodepside and PF1022A were compared, the latter was significantly less effective against mature adults following intraperitoneal (ED50 values of 6.1 vs. 55.7 mg/kg) or subcutaneous (ED50 values of 15.2 vs. 225.7 mg/kg) administration. Only minimal differences were observed following oral administration (ED50 values of 2.7 vs. 5.2 mg/kg). Triple and most single oral doses with moderate to high dosages of PF1022A showed complete efficacy against histotropic second stage larvae (3×100 mg/kg or 1×250 mg/kg), further developed larvae (3×10 mg/kg or 1×100 mg/kg) and immature adults (3×10 mg/kg or 1×100 mg/kg). Histotropic first stage larvae were only eliminated after three doses of PF1022A (3×100 mg/kg) but not after a single dose. Conclusions/Significance These results indicate that the cyclooctadepsipeptides are a drug class with promising candidates for further evaluation for the treatment of trichurosis of humans and livestock animals in single dose regimens. PMID:24587460

Booster propulsion/vehicle impact study

NASA Technical Reports Server (NTRS)

Weldon, Vincent; Dunn, Michael; Fink, Lawrence; Phillips, Dwight; Wetzel, Eric

1988-01-01

The use of hydrogen RP-1, propane, and methane as fuels for booster engines of launch vehicles is discussed. An automated procedure for integrated launch vehicle, engine sizing, and design optimization was used to define two stage and single stage concepts for minimum dry weight. The two stage vehicles were unmanned and used a flyback booster and partially reusable orbiter. The single stage designs were fully reusable, manned flyback vehicles. Comparisons of these vehicle designs, showing the effects of using different fuels, as well as sensitivity and trending data, are presented. In addition, the automated design technique utilized for the study is described.

Fabrication technique for a custom face mask for the treatment of obstructive sleep apnea.

PubMed

Prehn, Ronald S; Colquitt, Tom

2016-05-01

The development of the positive airway pressure custom mask (TAP-PAP CM) has changed the treatment of obstructive sleep apnea. The TAP-PAP CM is used in continuous positive airway pressure therapy (CPAP) and is fabricated from the impression of the face. This mask is then connected to a post screwed into the mechanism of the TAP3 (Thornton Anterior Positioner) oral appliance. This strapless CPAP face mask features an efficient and stable CPAP interface with mandibular stabilization (Hybrid Therapy). A technique with a 2-stage polyvinyl siloxane face impression is described that offers improvements over the established single-stage face impression. This 2-stage impression technique eliminates problems inherent in the single-stage face impression, including voids, compressed tissue, inadequate borders, and a rushed experience due to the setting time of the single stage. The result is a custom mask with an improved seal to the CPAP device. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

A phasing and imputation method for pedigreed populations that results in a single-stage genomic evaluation

PubMed Central

2012-01-01

Background Efficient, robust, and accurate genotype imputation algorithms make large-scale application of genomic selection cost effective. An algorithm that imputes alleles or allele probabilities for all animals in the pedigree and for all genotyped single nucleotide polymorphisms (SNP) provides a framework to combine all pedigree, genomic, and phenotypic information into a single-stage genomic evaluation. Methods An algorithm was developed for imputation of genotypes in pedigreed populations that allows imputation for completely ungenotyped animals and for low-density genotyped animals, accommodates a wide variety of pedigree structures for genotyped animals, imputes unmapped SNP, and works for large datasets. The method involves simple phasing rules, long-range phasing and haplotype library imputation and segregation analysis. Results Imputation accuracy was high and computational cost was feasible for datasets with pedigrees of up to 25 000 animals. The resulting single-stage genomic evaluation increased the accuracy of estimated genomic breeding values compared to a scenario in which phenotypes on relatives that were not genotyped were ignored. Conclusions The developed imputation algorithm and software and the resulting single-stage genomic evaluation method provide powerful new ways to exploit imputation and to obtain more accurate genetic evaluations. PMID:22462519

A systematic review of the evidence for single stage and two stage revision of infected knee replacement

PubMed Central

2013-01-01

Background Periprosthetic infection about the knee is a devastating complication that may affect between 1% and 5% of knee replacement. With over 79 000 knee replacements being implanted each year in the UK, periprosthetic infection (PJI) is set to become an important burden of disease and cost to the healthcare economy. One of the important controversies in treatment of PJI is whether a single stage revision operation is superior to a two-stage procedure. This study sought to systematically evaluate the published evidence to determine which technique had lowest reinfection rates. Methods A systematic review of the literature was undertaken using the MEDLINE and EMBASE databases with the aim to identify existing studies that present the outcomes of each surgical technique. Reinfection rate was the primary outcome measure. Studies of specific subsets of patients such as resistant organisms were excluded. Results 63 studies were identified that met the inclusion criteria. The majority of which (58) were reports of two-stage revision. Reinfection rated varied between 0% and 41% in two-stage studies, and 0% and 11% in single stage studies. No clinical trials were identified and the majority of studies were observational studies. Conclusions Evidence for both one-stage and two-stage revision is largely of low quality. The evidence basis for two-stage revision is significantly larger, and further work into direct comparison between the two techniques should be undertaken as a priority. PMID:23895421

Pre-Stall Behavior of a Transonic Axial Compressor Stage via Time-Accurate Numerical Simulation

NASA Technical Reports Server (NTRS)

Chen, Jen-Ping; Hathaway, Michael D.; Herrick, Gregory P.

2008-01-01

CFD calculations using high-performance parallel computing were conducted to simulate the pre-stall flow of a transonic compressor stage, NASA compressor Stage 35. The simulations were run with a full-annulus grid that models the 3D, viscous, unsteady blade row interaction without the need for an artificial inlet distortion to induce stall. The simulation demonstrates the development of the rotating stall from the growth of instabilities. Pressure-rise performance and pressure traces are compared with published experimental data before the study of flow evolution prior to the rotating stall. Spatial FFT analysis of the flow indicates a rotating long-length disturbance of one rotor circumference, which is followed by a spike-type breakdown. The analysis also links the long-length wave disturbance with the initiation of the spike inception. The spike instabilities occur when the trajectory of the tip clearance flow becomes perpendicular to the axial direction. When approaching stall, the passage shock changes from a single oblique shock to a dual-shock, which distorts the perpendicular trajectory of the tip clearance vortex but shows no evidence of flow separation that may contribute to stall.