Precision phase control for the radio frequency system of K500 superconducting cyclotron at Variable Energy Cyclotron Centre, Kolkata

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

Som, Sumit; Ghosh, Surajit; Seth, Sudeshna

2013-11-15

Variable Energy Cyclotron Centre (VECC) has commissioned K500 Superconducting cyclotron (SCC) based on MSU and Texas A and M university cyclotrons. The radio frequency (RF) system of SCC has been commissioned with the stringent requirement of various RF parameters. The three-phase RF system of Superconducting cyclotron has been developed in the frequency range 9–27 MHz with amplitude and phase stability of 100 ppm and ±0.1°, respectively. The phase control system has the option to change the relative phase difference between any two RF cavities and maintain the phase stability within ±0.1° during round-the-clock cyclotron operation. The said precision phase loopmore » consists of both analogue In-phase/Quadrature modulator to achieve faster response and also Direct Digital Synthesis based phase shifter to achieve wide dynamic range as well. This paper discusses detail insights into the various issues of phase control for the K500 SCC at VECC, Kolkata.« less

Comparison of the trunk-pelvis and lower extremities sagittal plane inter-segmental coordination and variability during walking in persons with and without chronic low back pain.

PubMed

Ebrahimi, Samaneh; Kamali, Fahimeh; Razeghi, Mohsen; Haghpanah, Seyyed Arash

2017-04-01

Inter-segmental coordination can be influenced by chronic low back pain (CLBP). The sagittal plane lower extremities inter-segmental coordination pattern and variability, in conjunction with the pelvis and trunk, were assessed in subjects with and without non-specific CLBP during free-speed walking. Kinematic data were collected from 10 non-specific CLBP and 10 non-CLBP control volunteers while the subjects were walking at their preferred speed. Sagittal plane time-normalized segmental angles and velocities were used to calculate continuous relative phase for each data point. Mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify the trunk-pelvis and bilateral pelvis-thigh, thigh-shank and shank-foot coordination pattern and variability over the stance and swing phases of gait. Mann-Whitney U test was employed to compare the means of DP and MARP values between two groups (same side comparison). Statistical analysis revealed more in-phase/less variable trunk-pelvis coordination in the CLBP group (P<0.05). CLBP group demonstrated less variable right or left pelvis-thigh coordination pattern (P<0.05). Moreover, the left thigh-shank and left shank-foot MARP values in the CLBP group, were more in-phase than left MARP values in the non-CLBP control group during the swing phase (P<0.05). In conclusion, the sagittal plane lower extremities, pelvis and trunk coordination pattern and variability could be generally affected by CLBP during walking. These changes can be possible compensatory strategies of the motor control system which can be considered in the CLBP subjects. Copyright © 2017 Elsevier B.V. All rights reserved.

Measuring P-V-T Phase Behavior with a Variable Volume View Cell

ERIC Educational Resources Information Center

Hoffmann, Markus M.; Salter, Jason D.

2004-01-01

An experiment using a variable volume cell is presented where students actively control and directly observe the phase equilibrium inside the view cell. Measuring and exploring P-V-T phase behavior through dielectric constant measurements conveys the important concept that solvent behavior can be changed continuously in the sc fluid state.

Sleep and circadian variability in people with delayed sleep-wake phase disorder versus healthy controls.

PubMed

Burgess, Helen J; Park, Margaret; Wyatt, James K; Rizvydeen, Muneer; Fogg, Louis F

2017-06-01

To compare sleep and circadian variability in adults with delayed sleep-wake phase disorder (DSWPD) to healthy controls. Forty participants (22 DSWPD, 18 healthy controls) completed a ten-day protocol, consisting of DLMO assessments on two consecutive nights, a five-day study break, followed by two more DLMO assessments. All participants were instructed to sleep within one hour of their self-reported average sleep schedule for the last four days of the study break. We analyzed the participants' wrist actigraphy data during these four days to examine intraindividual variability in sleep timing, duration and efficiency. We also examined shifts in the DLMO from before and after the study break. Under the same conditions, people with DSWPD had significantly more variable wake times and total sleep time than healthy controls (p ≤ 0.015). Intraindividual variability in sleep onset time and sleep efficiency was similar between the two groups (p ≥ 0.30). The DLMO was relatively stable across the study break, with only 11% of controls but 27% of DSWPDs showed more than a one hour shift in the DLMO. Only in the DSWPD sample was greater sleep variability associated with a larger shift in the DLMO (r = 0.46, p = 0.03). These results suggest that intraindividual variability in sleep can be higher in DSWPD versus healthy controls, and this may impact variability in the DLMO. DSWPD patients with higher intraindividual variability in sleep are more likely to have a shifting DLMO, which could impact sleep symptoms and the optimal timing of light and/or melatonin treatment for DSWPD. Circadian Phase Assessments at Home, http://clinicaltrials.gov/show/NCT01487252, NCT01487252. Copyright © 2017 Elsevier B.V. All rights reserved.

Polarization imaging apparatus

NASA Technical Reports Server (NTRS)

Zou, Yingyin Kevin (Inventor); Chen, Qiushui (Inventor); Zhao, Hongzhi (Inventor)

2010-01-01

A polarization imaging apparatus measures the Stokes image of a sample. The apparatus consists of an optical lens set 11, a linear polarizer 14 with its optical axis 18, a first variable phase retarder 12 with its optical axis 16 aligned 22.5.degree. to axis 18, a second variable phase retarder 13 with its optical axis 17 aligned 45.degree. to axis 18, a imaging sensor 15 for sensing the intensity images of the sample, a controller 101 and a computer 102. Two variable phase retarders 12 and 13 were controlled independently by a computer 102 through a controller unit 101 which generates a sequential of voltages to control the phase retardations of VPRs 12 and 13. A set of four intensity images, I.sub.0, I.sub.1, I.sub.2 and I.sub.3 of the sample were captured by imaging sensor 15 when the phase retardations of VPRs 12 and 13 were set at (0,0), (.pi.,0), (.pi.,.pi.) and (.pi./2,.pi.), respectively Then four Stokes components of a Stokes image, S.sub.0, S.sub.1, S.sub.2 and S.sub.3 were calculated using the four intensity images.

Animal-to-animal variability in the phasing of the crustacean cardiac motor pattern: an experimental and computational analysis

PubMed Central

Williams, Alex H.; Kwiatkowski, Molly A.; Mortimer, Adam L.; Marder, Eve; Zeeman, Mary Lou

2013-01-01

The cardiac ganglion (CG) of Homarus americanus is a central pattern generator that consists of two oscillatory groups of neurons: “small cells” (SCs) and “large cells” (LCs). We have shown that SCs and LCs begin their bursts nearly simultaneously but end their bursts at variable phases. This variability contrasts with many other central pattern generator systems in which phase is well maintained. To determine both the consequences of this variability and how CG phasing is controlled, we modeled the CG as a pair of Morris-Lecar oscillators coupled by electrical and excitatory synapses and constructed a database of 15,000 simulated networks using random parameter sets. These simulations, like our experimental results, displayed variable phase relationships, with the bursts beginning together but ending at variable phases. The model suggests that the variable phasing of the pattern has important implications for the functional role of the excitatory synapses. In networks in which the two oscillators had similar duty cycles, the excitatory coupling functioned to increase cycle frequency. In networks with disparate duty cycles, it functioned to decrease network frequency. Overall, we suggest that the phasing of the CG may vary without compromising appropriate motor output and that this variability may critically determine how the network behaves in response to manipulations. PMID:23446690

Motion makes sense: an adaptive motor-sensory strategy underlies the perception of object location in rats.

PubMed

Saraf-Sinik, Inbar; Assa, Eldad; Ahissar, Ehud

2015-06-10

Tactile perception is obtained by coordinated motor-sensory processes. We studied the processes underlying the perception of object location in freely moving rats. We trained rats to identify the relative location of two vertical poles placed in front of them and measured at high resolution the motor and sensory variables (19 and 2 variables, respectively) associated with this whiskers-based perceptual process. We found that the rats developed stereotypic head and whisker movements to solve this task, in a manner that can be described by several distinct behavioral phases. During two of these phases, the rats' whiskers coded object position by first temporal and then angular coding schemes. We then introduced wind (in two opposite directions) and remeasured their perceptual performance and motor-sensory variables. Our rats continued to perceive object location in a consistent manner under wind perturbations while maintaining all behavioral phases and relatively constant sensory coding. Constant sensory coding was achieved by keeping one group of motor variables (the "controlled variables") constant, despite the perturbing wind, at the cost of strongly modulating another group of motor variables (the "modulated variables"). The controlled variables included coding-relevant variables, such as head azimuth and whisker velocity. These results indicate that consistent perception of location in the rat is obtained actively, via a selective control of perception-relevant motor variables. Copyright © 2015 the authors 0270-6474/15/358777-13$15.00/0.

Digital phase-locked loop speed control for a brushless dc motor

NASA Astrophysics Data System (ADS)

Wise, M. G.

1985-06-01

Speed control of d.c. motors by phase-locked loops (PLL) is becoming increasingly popular. Primary interest has been in employing PLL for constant speed control. This thesis investigates the theory and techniques of digital PLL to speed control of a brushless d.c. motor with a variable speed of operation. Addition of logic controlled count enable/disable to a synchronous up/down counter, used as a phase-frequency detector, is shown to improve the performance of previously proposed PLL control schemes.

A design concept for an MMIC (Monolithic Microwave Integrated Circuit) microstrip phased array

NASA Technical Reports Server (NTRS)

Lee, Richard Q.; Smetana, Jerry; Acosta, Roberto

1987-01-01

A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka proposed design, which concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required.

Can Dynamic Visualizations with Variable Control Enhance the Acquisition of Intuitive Knowledge?

NASA Astrophysics Data System (ADS)

Wichmann, Astrid; Timpe, Sebastian

2015-10-01

An important feature of inquiry learning is to take part in science practices including exploring variables and testing hypotheses. Computer-based dynamic visualizations have the potential to open up various exploration possibilities depending on the level of learner control. It is assumed that variable control, e.g., by changing parameters of a variable, leads to deeper processing (Chang and Linn 2013; de Jong and Njoo 1992; Nerdel 2003; Trey and Khan 2008). Variable control may be helpful, in particular, for acquiring intuitive knowledge (Swaak and de Jong 2001). However, it bares the risk of mental exhaustion and thus may have detrimental effects on knowledge acquisition (Sweller 1998). Students ( N = 118) from four chemistry classes followed inquiry cycles using the software Molecular Workbench (Xie and Tinker 2006). Variable control was varied across the conditions (1) No-Manipulation group and (2) Manipulation group. By adding a third condition, (3) Manipulation-Plus group, we tested whether adding an active hypothesis phase prepares students before changing parameters of a variable. As expected, students in the Manipulation group and Manipulation-Plus group performed better concerning intuitive knowledge ( d = 1.14) than students in the No-Manipulation group. On a descriptive level, results indicated higher cognitive effort in the Manipulation group and the Manipulation-Plus group than in the No-Manipulation group. Unexpectedly, students in the Manipulation-Plus group did not benefit from the active hypothesis phase (intuitive knowledge: d = .36). Findings show that students benefit from variable control. Furthermore, findings point toward the direction that variable control evokes desirable difficulties (Bjork and Linn 2006).

Analysis of a Linear System for Variable-Thrust Control in the Terminal Phase of Rendezvous

NASA Technical Reports Server (NTRS)

Hord, Richard A.; Durling, Barbara J.

1961-01-01

A linear system for applying thrust to a ferry vehicle in the 3 terminal phase of rendezvous with a satellite is analyzed. This system requires that the ferry thrust vector per unit mass be variable and equal to a suitable linear combination of the measured position and velocity vectors of the ferry relative to the satellite. The variations of the ferry position, speed, acceleration, and mass ratio are examined for several combinations of the initial conditions and two basic control parameters analogous to the undamped natural frequency and the fraction of critical damping. Upon making a desirable selection of one control parameter and requiring minimum fuel expenditure for given terminal-phase initial conditions, a simplified analysis in one dimension practically fixes the choice of the remaining control parameter. The system can be implemented by an automatic controller or by a pilot.

Continuous-variable geometric phase and its manipulation for quantum computation in a superconducting circuit.

PubMed

Song, Chao; Zheng, Shi-Biao; Zhang, Pengfei; Xu, Kai; Zhang, Libo; Guo, Qiujiang; Liu, Wuxin; Xu, Da; Deng, Hui; Huang, Keqiang; Zheng, Dongning; Zhu, Xiaobo; Wang, H

2017-10-20

Geometric phase, associated with holonomy transformation in quantum state space, is an important quantum-mechanical effect. Besides fundamental interest, this effect has practical applications, among which geometric quantum computation is a paradigm, where quantum logic operations are realized through geometric phase manipulation that has some intrinsic noise-resilient advantages and may enable simplified implementation of multi-qubit gates compared to the dynamical approach. Here we report observation of a continuous-variable geometric phase and demonstrate a quantum gate protocol based on this phase in a superconducting circuit, where five qubits are controllably coupled to a resonator. Our geometric approach allows for one-step implementation of n-qubit controlled-phase gates, which represents a remarkable advantage compared to gate decomposition methods, where the number of required steps dramatically increases with n. Following this approach, we realize these gates with n up to 4, verifying the high efficiency of this geometric manipulation for quantum computation.

Dynamic control of nutrient-removal from industrial wastewater in a sequencing batch reactor, using common and low-cost online sensors.

PubMed

Dries, Jan

2016-01-01

On-line control of the biological treatment process is an innovative tool to cope with variable concentrations of chemical oxygen demand and nutrients in industrial wastewater. In the present study we implemented a simple dynamic control strategy for nutrient-removal in a sequencing batch reactor (SBR) treating variable tank truck cleaning wastewater. The control system was based on derived signals from two low-cost and robust sensors that are very common in activated sludge plants, i.e. oxidation reduction potential (ORP) and dissolved oxygen. The amount of wastewater fed during anoxic filling phases, and the number of filling phases in the SBR cycle, were determined by the appearance of the 'nitrate knee' in the profile of the ORP. The phase length of the subsequent aerobic phases was controlled by the oxygen uptake rate measured online in the reactor. As a result, the sludge loading rate (F/M ratio), the volume exchange rate and the SBR cycle length adapted dynamically to the activity of the activated sludge and the actual characteristics of the wastewater, without affecting the final effluent quality.

Methods to control for unmeasured confounding in pharmacoepidemiology: an overview.

PubMed

Uddin, Md Jamal; Groenwold, Rolf H H; Ali, Mohammed Sanni; de Boer, Anthonius; Roes, Kit C B; Chowdhury, Muhammad A B; Klungel, Olaf H

2016-06-01

Background Unmeasured confounding is one of the principal problems in pharmacoepidemiologic studies. Several methods have been proposed to detect or control for unmeasured confounding either at the study design phase or the data analysis phase. Aim of the Review To provide an overview of commonly used methods to detect or control for unmeasured confounding and to provide recommendations for proper application in pharmacoepidemiology. Methods/Results Methods to control for unmeasured confounding in the design phase of a study are case only designs (e.g., case-crossover, case-time control, self-controlled case series) and the prior event rate ratio adjustment method. Methods that can be applied in the data analysis phase include, negative control method, perturbation variable method, instrumental variable methods, sensitivity analysis, and ecological analysis. A separate group of methods are those in which additional information on confounders is collected from a substudy. The latter group includes external adjustment, propensity score calibration, two-stage sampling, and multiple imputation. Conclusion As the performance and application of the methods to handle unmeasured confounding may differ across studies and across databases, we stress the importance of using both statistical evidence and substantial clinical knowledge for interpretation of the study results.

Robust Adaptive Flight Control Design of Air-breathing Hypersonic Vehicles

DTIC Science & Technology

2016-12-07

dynamic inversion controller design for a non -minimum phase hypersonic vehicle is derived by Kuipers et al. [2008]. Moreover, integrated guidance and...stabilization time for inner loop variables is lesser than the intermediate loop variables because of the three-loop-control design methodology . The control...adaptive design . Control Engineering Practice, 2016. Michael A Bolender and David B Doman. A non -linear model for the longitudinal dynamics of a

The Education of Attention as Explanation of Variability of Practice Effects : Learning the Final Approach Phase in a Flight Simulator

ERIC Educational Resources Information Center

Huet, Michael; Jacobs, David M.; Camachon, Cyril; Missenard, Olivier; Gray, Rob; Montagne, Gilles

2011-01-01

The present study reports two experiments in which a total of 20 participants without prior flight experience practiced the final approach phase in a fixed-base simulator. All participants received self-controlled concurrent feedback during 180 practice trials. Experiment 1 shows that participants learn more quickly under variable practice…

Two-phase strategy of controlling motor coordination determined by task performance optimality.

PubMed

Shimansky, Yury P; Rand, Miya K

2013-02-01

A quantitative model of optimal coordination between hand transport and grip aperture has been derived in our previous studies of reach-to-grasp movements without utilizing explicit knowledge of the optimality criterion or motor plant dynamics. The model's utility for experimental data analysis has been demonstrated. Here we show how to generalize this model for a broad class of reaching-type, goal-directed movements. The model allows for measuring the variability of motor coordination and studying its dependence on movement phase. The experimentally found characteristics of that dependence imply that execution noise is low and does not affect motor coordination significantly. From those characteristics it is inferred that the cost of neural computations required for information acquisition and processing is included in the criterion of task performance optimality as a function of precision demand for state estimation and decision making. The precision demand is an additional optimized control variable that regulates the amount of neurocomputational resources activated dynamically. It is shown that an optimal control strategy in this case comprises two different phases. During the initial phase, the cost of neural computations is significantly reduced at the expense of reducing the demand for their precision, which results in speed-accuracy tradeoff violation and significant inter-trial variability of motor coordination. During the final phase, neural computations and thus motor coordination are considerably more precise to reduce the cost of errors in making a contact with the target object. The generality of the optimal coordination model and the two-phase control strategy is illustrated on several diverse examples.

Sleep and Circadian Variability in People with Delayed Sleep-Wake Phase Disorder versus Healthy Controls

PubMed Central

Burgess, Helen J.; Park, Margaret; Wyatt, James K.; Rizvydeen, Muneer; Fogg, Louis F.

2017-01-01

Objective/Background To compare sleep and circadian variability in adults with delayed sleep-wake phase disorder (DSWPD) to healthy controls. Patients/Methods Forty participants (22 DSWPD, 18 healthy controls) completed a 10-day protocol, consisting of DLMO assessments on two consecutive nights, a five-day study break, followed by two more DLMO assessments. All participants were instructed to sleep within one hour of their self-reported average sleep schedule for the last four days of the study break. We analyzed the participants’ wrist actigraphy data during these four days to examine intraindividual variability in sleep timing, duration and efficiency. We also examined shifts in the DLMO from before and after the study break. Results and Conclusions Under the same conditions, people with DSWPD had significantly more variable wake times and total sleep time than healthy controls (p≤0.015). Intraindividual variability in sleep onset time and sleep efficiency was similar between the two groups (p≥0.30). The DLMO was relatively stable across the study break, with only 11% of controls but 27% of DSWPDs showed more than a one hour shift in the DLMO. Only in the DSWPD sample was greater sleep variability associated with a larger shift in the DLMO (r=0.46, p=0.03). These results suggest that intraindividual variability in sleep can be higher in DSWPD versus healthy controls, and this may impact variability in the DLMO. DSWPD patients with higher intraindividual variability in sleep are more likely to have a shifting DLMO, which could impact sleep symptoms and the optimal timing of light and/or melatonin treatment for DSWPD. PMID:28522096

Position control system for use with micromechanical actuators

DOEpatents

Guckel, Henry; Stiers, Eric W.

2000-01-01

A positioning system adapted for use with micromechanical actuators provides feedback control of the position of the movable element of the actuator utilizing a low Q sensing coil. The effective inductance of the sensing coil changes with position of the movable element to change the frequency of oscillation of a variable oscillator. The output of the variable oscillator is compared in a phase detector to a reference oscillator signal. The phase detector provides a pulsed output having a pulse duty cycle related to the phase or frequency difference between the oscillator signals. The output of the phase detector is provided to a drive coil which applies a magnetic force to the movable element which balances the force of a spring. The movable element can be displaced to a new position by changing the frequency of the reference oscillator.

Knee motion variability in patients with knee osteoarthritis: the effect of self-reported instability

PubMed Central

Gustafson, Jonathan A.; Robinson, Megan E.; Fitzgerald, G. Kelley; Tashman, Scott; Farrokhi, Shawn

2015-01-01

Background Knee osteoarthritis has been previously associated with a stereotypical knee-stiffening gait pattern and reduced knee joint motion variability due to increased antagonist muscle co-contractions and smaller utilized arc of motion during gait. However, episodic self-reported instability may be a sign of excessive motion variability for a large subgroup of patients with knee osteoarthritis. The objective of this work was to evaluate the differences in knee joint motion variability during gait in patients with knee osteoarthritis with and without self-reported instability compared to a control group of older adults with asymptomatic knees. Methods Forty-three subjects, 8 with knee osteoarthritis but no reports of instability (stable), 11 with knee osteoarthritis and self-reported instability (unstable), and 24 without knee osteoarthritis or instability (control) underwent Dynamic Stereo X-ray analysis during a decline gait task on a treadmill. Knee motion variability was assessed using parametric phase plots during the loading response phase of decline gait. Findings The stable group demonstrated decreased sagittal-plane motion variability compared to the control group (p=0.04), while the unstable group demonstrated increased sagittal-plane motion variability compared to the control (p=0.003) and stable groups (p<0.001). The unstable group also demonstrated increased anterior-posterior joint contact point motion variability for the medial tibiofemoral compartment compared to the control (p=0.03) and stable groups (p=0.03). Interpretation The finding of decreased knee motion variability in patients with knee osteoarthritis without self-reported instability supports previous research. However, presence of self-reported instability is associated with increased knee motion variability in patients with knee osteoarthritis and warrants further investigation. PMID:25796536

Combinational logic for generating gate drive signals for phase control rectifiers

NASA Technical Reports Server (NTRS)

Dolland, C. R.; Trimble, D. W. (Inventor)

1982-01-01

Control signals for phase-delay rectifiers, which require a variable firing angle that ranges from 0 deg to 180 deg, are derived from line-to-line 3-phase signals and both positive and negative firing angle control signals which are generated by comparing current command and actual current. Line-to-line phases are transformed into line-to-neutral phases and integrated to produce 90 deg phase delayed signals that are inverted to produce three cosine signals, such that for each its maximum occurs at the intersection of positive half cycles of the other two phases which are inputs to other inverters. At the same time, both positive and negative (inverted) phase sync signals are generated for each phase by comparing each with the next and producing a square wave when it is greater. Ramp, sync and firing angle controls signals are than used in combinational logic to generate the gate firing control signals SCR gate drives which fire SCR devices in a bridge circuit.

SINFAC - SYSTEMS IMPROVED NUMERICAL FLUIDS ANALYSIS CODE

NASA Technical Reports Server (NTRS)

Costello, F. A.

1994-01-01

The Systems Improved Numerical Fluids Analysis Code, SINFAC, consists of additional routines added to the April 1983 revision of SINDA, a general thermal analyzer program. The purpose of the additional routines is to allow for the modeling of active heat transfer loops. The modeler can simulate the steady-state and pseudo-transient operations of 16 different heat transfer loop components including radiators, evaporators, condensers, mechanical pumps, reservoirs and many types of valves and fittings. In addition, the program contains a property analysis routine that can be used to compute the thermodynamic properties of 20 different refrigerants. SINFAC can simulate the response to transient boundary conditions. SINFAC was first developed as a method for computing the steady-state performance of two phase systems. It was then modified using CNFRWD, SINDA's explicit time-integration scheme, to accommodate transient thermal models. However, SINFAC cannot simulate pressure drops due to time-dependent fluid acceleration, transient boil-out, or transient fill-up, except in the accumulator. SINFAC also requires the user to be familiar with SINDA. The solution procedure used by SINFAC is similar to that which an engineer would use to solve a system manually. The solution to a system requires the determination of all of the outlet conditions of each component such as the flow rate, pressure, and enthalpy. To obtain these values, the user first estimates the inlet conditions to the first component of the system, then computes the outlet conditions from the data supplied by the manufacturer of the first component. The user then estimates the temperature at the outlet of the third component and computes the corresponding flow resistance of the second component. With the flow resistance of the second component, the user computes the conditions down stream, namely the inlet conditions of the third. The computations follow for the rest of the system, back to the first component. On the first pass, the user finds that the calculated outlet conditions of the last component do not match the estimated inlet conditions of the first. The user then modifies the estimated inlet conditions of the first component in an attempt to match the calculated values. The user estimated values are called State Variables. The differences between the user estimated values and calculated values are called the Error Variables. The procedure systematically changes the State Variables until all of the Error Variables are less than the user-specified iteration limits. The solution procedure is referred to as SCX. It consists of two phases, the Systems phase and the Controller phase. The X is to imply experimental. SCX computes each next set of State Variables in two phases. In the first phase, SCX fixes the controller positions and modifies the other State Variables by the Newton-Raphson method. This first phase is the Systems phase. Once the Newton-Raphson method has solved the problem for the fixed controller positions, SCX next calculates new controller positions based on Newton's method while treating each sensor-controller pair independently but allowing all to change in one iteration. This phase is the Controller phase. SINFAC is available by license for a period of ten (10) years to approved licensees. The licenced program product includes the source code for the additional routines to SINDA, the SINDA object code, command procedures, sample data and supporting documentation. Additional documentation may be purchased at the price below. SINFAC was created for use on a DEC VAX under VMS. Source code is written in FORTRAN 77, requires 180k of memory, and should be fully transportable. The program was developed in 1988.

Maximum wind energy extraction strategies using power electronic converters

NASA Astrophysics Data System (ADS)

Wang, Quincy Qing

2003-10-01

This thesis focuses on maximum wind energy extraction strategies for achieving the highest energy output of variable speed wind turbine power generation systems. Power electronic converters and controls provide the basic platform to accomplish the research of this thesis in both hardware and software aspects. In order to send wind energy to a utility grid, a variable speed wind turbine requires a power electronic converter to convert a variable voltage variable frequency source into a fixed voltage fixed frequency supply. Generic single-phase and three-phase converter topologies, converter control methods for wind power generation, as well as the developed direct drive generator, are introduced in the thesis for establishing variable-speed wind energy conversion systems. Variable speed wind power generation system modeling and simulation are essential methods both for understanding the system behavior and for developing advanced system control strategies. Wind generation system components, including wind turbine, 1-phase IGBT inverter, 3-phase IGBT inverter, synchronous generator, and rectifier, are modeled in this thesis using MATLAB/SIMULINK. The simulation results have been verified by a commercial simulation software package, PSIM, and confirmed by field test results. Since the dynamic time constants for these individual models are much different, a creative approach has also been developed in this thesis to combine these models for entire wind power generation system simulation. An advanced maximum wind energy extraction strategy relies not only on proper system hardware design, but also on sophisticated software control algorithms. Based on literature review and computer simulation on wind turbine control algorithms, an intelligent maximum wind energy extraction control algorithm is proposed in this thesis. This algorithm has a unique on-line adaptation and optimization capability, which is able to achieve maximum wind energy conversion efficiency through continuously improving the performance of wind power generation systems. This algorithm is independent of wind power generation system characteristics, and does not need wind speed and turbine speed measurements. Therefore, it can be easily implemented into various wind energy generation systems with different turbine inertia and diverse system hardware environments. In addition to the detailed description of the proposed algorithm, computer simulation results are presented in the thesis to demonstrate the advantage of this algorithm. As a final confirmation of the algorithm feasibility, the algorithm has been implemented inside a single-phase IGBT inverter, and tested with a wind simulator system in research laboratory. Test results were found consistent with the simulation results. (Abstract shortened by UMI.)

Ocean carbon and heat variability in an Earth System Model

NASA Astrophysics Data System (ADS)

Thomas, J. L.; Waugh, D.; Gnanadesikan, A.

2016-12-01

Ocean carbon and heat content are very important for regulating global climate. Furthermore, due to lack of observations and dependence on parameterizations, there has been little consensus in the modeling community on the magnitude of realistic ocean carbon and heat content variability, particularly in the Southern Ocean. We assess the differences between global oceanic heat and carbon content variability in GFDL ESM2Mc using a 500-year, pre-industrial control simulation. The global carbon and heat content are directly out of phase with each other; however, in the Southern Ocean the heat and carbon content are in phase. The global heat mutli-decadal variability is primarily explained by variability in the tropics and mid-latitudes, while the variability in global carbon content is primarily explained by Southern Ocean variability. In order to test the robustness of this relationship, we use three additional pre-industrial control simulations using different mesoscale mixing parameterizations. Three pre-industrial control simulations are conducted with the along-isopycnal diffusion coefficient (Aredi) set to constant values of 400, 800 (control) and 2400 m2 s-1. These values for Aredi are within the range of parameter settings commonly used in modeling groups. Finally, one pre-industrial control simulation is conducted where the minimum in the Gent-McWilliams parameterization closure scheme (AGM) increased to 600 m2 s-1. We find that the different simulations have very different multi-decadal variability, especially in the Weddell Sea where the characteristics of deep convection are drastically changed. While the temporal frequency and amplitude global heat and carbon content changes significantly, the overall spatial pattern of variability remains unchanged between the simulations.

A novel approach to controlling the phase angle of a variable switched reluctance motor for electric vehicle propulsion using the statistic matrix norm

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

Holling, G.H.

1994-12-31

Variable switched reluctance (VSR) motors are gaining importance for industrial applications. The paper will introduce a novel approach to simplify the computation involved in the control of VSR motors. Results are shown, that validate the approach and demonstrates the superior performance compared to tabulated control parameters with linear interpolation, which are widely used in implementations.

Investigation of phase-change coatings for variable thermal control of spacecraft

NASA Technical Reports Server (NTRS)

Kelliher, W. C.; Young, P. R.

1972-01-01

An investigation was conducted to determine the feasibility of producing a spacecraft coating system that could vary the ratio of its solar absorptance to thermal emittance to adjust automatically for changes in the thermal balance of a spacecraft. This study resulted in a new concept called the phase-change effect which uses the change that occurs in the optical properties of many materials during the phase transition from a crystalline solid to an amorphous material. A series of two-component model coatings was developed which, when placed on a highly reflecting substrate, exhibited a sharp decrease in solar absorptance within a narrow temperature range. A variable thermal control coating can have a significant amount of temperature regulation with the phase-change effect. Data are presented on several crystallite-polymer formulations, their physical and optical properties, and associated phase-change temperatures. Aspects pertaining to their use in a space environment and an example of the degree of thermal regulation attainable with these coatings is also given.

European land CO2 sink influenced by NAO and East-Atlantic Pattern coupling

PubMed Central

Bastos, Ana; Janssens, Ivan A.; Gouveia, Célia M.; Trigo, Ricardo M.; Ciais, Philippe; Chevallier, Frédéric; Peñuelas, Josep; Rödenbeck, Christian; Piao, Shilong; Friedlingstein, Pierre; Running, Steven W.

2016-01-01

Large-scale climate patterns control variability in the global carbon sink. In Europe, the North-Atlantic Oscillation (NAO) influences vegetation activity, however the East-Atlantic (EA) pattern is known to modulate NAO strength and location. Using observation-driven and modelled data sets, we show that multi-annual variability patterns of European Net Biome Productivity (NBP) are linked to anomalies in heat and water transport controlled by the NAO–EA interplay. Enhanced NBP occurs when NAO and EA are both in negative phase, associated with cool summers with wet soils which enhance photosynthesis. During anti-phase periods, NBP is reduced through distinct impacts of climate anomalies in photosynthesis and respiration. The predominance of anti-phase years in the early 2000s may explain the European-wide reduction of carbon uptake during this period, reported in previous studies. Results show that improving the capability of simulating atmospheric circulation patterns may better constrain regional carbon sink variability in coupled carbon-climate models. PMID:26777730

European land CO2 sink influenced by NAO and East-Atlantic Pattern coupling.

PubMed

Bastos, Ana; Janssens, Ivan A; Gouveia, Célia M; Trigo, Ricardo M; Ciais, Philippe; Chevallier, Frédéric; Peñuelas, Josep; Rödenbeck, Christian; Piao, Shilong; Friedlingstein, Pierre; Running, Steven W

2016-01-18

Large-scale climate patterns control variability in the global carbon sink. In Europe, the North-Atlantic Oscillation (NAO) influences vegetation activity, however the East-Atlantic (EA) pattern is known to modulate NAO strength and location. Using observation-driven and modelled data sets, we show that multi-annual variability patterns of European Net Biome Productivity (NBP) are linked to anomalies in heat and water transport controlled by the NAO-EA interplay. Enhanced NBP occurs when NAO and EA are both in negative phase, associated with cool summers with wet soils which enhance photosynthesis. During anti-phase periods, NBP is reduced through distinct impacts of climate anomalies in photosynthesis and respiration. The predominance of anti-phase years in the early 2000s may explain the European-wide reduction of carbon uptake during this period, reported in previous studies. Results show that improving the capability of simulating atmospheric circulation patterns may better constrain regional carbon sink variability in coupled carbon-climate models.

Cognitive inconsistency in bipolar patients is determined by increased intra-individual variability in initial phase of task performance.

PubMed

Krukow, Paweł; Szaniawska, Ola; Harciarek, Michał; Plechawska-Wójcik, Małgorzata; Jonak, Kamil

2017-03-01

Bipolar patients show high intra-individual variability during cognitive processing. However, it is not known whether there are a specific fluctuations of variability contributing to the overall high cognitive inconsistency. The objective was to compare dynamic profiles of patients and healthy controls to identify hypothetical differences and their associations with overall variability and processing speed. Changes of reaction times iSD during processing speed test performance over time was measured by dividing the iSD for whole task into four consecutive parts. Motor speed and cognitive effort were controlled. Patients with BD exhibited significantly lower results regarding processing speed and higher intra-individual variability comparing with HC. The profile of intra-individual variability changes over time of performance was significantly different in BD versus HC groups: F(3, 207)=8.60, p<0.0001, η p 2 =0.11. iSD of BD patients in the initial phase of performance was three times higher than in the last. There was no significant differences between four intervals in HC group. Inter-group difference in the initial part of the profiles was significant also after controlling for several cognitive and clinical variables. Applied computer version of Cognitive Speed Test was relatively new and, thus, replication studies are needed. Effect seen in the present study is driven mainly by the BD type I. Patients with BD exhibits problems with setting a stimulus-response association in starting phase of cognitive processing. This deficit may negatively interfere with the other cognitive functions, decreasing level of psychosocial functioning, therefore should be explored in future studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Phase 1 of the automated array assembly task of the low cost silicon solar array project

NASA Technical Reports Server (NTRS)

Pryor, R. A.; Grenon, L. A.; Coleman, M. G.

1978-01-01

The results of a study of process variables and solar cell variables are presented. Interactions between variables and their effects upon control ranges of the variables are identified. The results of a cost analysis for manufacturing solar cells are discussed. The cost analysis includes a sensitivity analysis of a number of cost factors.

Diagnosing GCM errors over West Africa using relaxation experiments. Part II: intraseasonal variability and African easterly waves

NASA Astrophysics Data System (ADS)

Pohl, Benjamin; Douville, Hervé

2011-10-01

A near-global grid-point nudging of the Arpege-Climat atmospheric General Circulation Model towards ECMWF reanalyses is used to diagnose the regional versus remote origin of the summer model biases and variability over West Africa. First part of this study revealed a limited impact on the monsoon climatology compared to a control experiment without nudging, but a significant improvement of interannual variability, although the amplitude of the seasonal anomalies remained underestimated. Focus is given here on intraseasonal variability of monsoon rainfall and dynamics. The reproducible part of these signals is investigated through 30-member ensemble experiments computed for the 1994 rainy season, a year abnormally wet over the Sahel but representative of the model systematic biases. In the control experiment, Arpege-Climat simulates too few rainy days that are associated with too low rainfall amounts over the central and western Sahel, in line with the seasonal dry biases. Nudging the model outside Africa tends to slightly increase the number of rainy days over the Sahel, but has little effect on associated rainfall amounts. However, results do indicate that a significant part of the monsoon intraseasonal variability simulated by Arpege-Climat is controlled by lateral boundary conditions. Parts of the wet/dry spells over the Sahel occur in phase in the 30 members of the nudging experiment, and are therefore embedded in larger-scale variability patterns. Inter-member spread is however not constant across the selected summer season. It is partly controlled by African Easterly Waves, which show dissimilar amplitude from one member to another, but a coherent phasing in all members. A lowpass filtering of the nudging fields suggests that low frequency variations in the lateral boundary conditions can lead to eastward extensions of the African Easterly Jet, creating a favorable environment for easterly waves, while high frequency perturbations seem to control their phasing.

All optical controlled photonic integrated circuits using azo dye functionized sol-gel material

NASA Astrophysics Data System (ADS)

Ke, Xianjun

The main focus of this dissertation is development and characterization of all-optical controllable azo dye functionized sol gel material, demonstrating a PIC fabrication technique on glass substrate using such material, and exploration and feasibility demonstration of three PIC functional devices namely optical variable attenuator, optical switches, and optical tunable filters using the material. The realization of all the devices in this dissertation are based on one material: dye functionalized sol-gel material. A photochromic sol-gel material functionalized with azo dye was synthesized and characterized. It possesses a photochromic characteristic under the control of green laser beam illumination. The material characteristics suggest the possibility of a new promising material platform candidate for the fabrication of alloptical controlled photonic integrated circuits. As the first potential application of the dye functionalized sol-gel material, an alloptical variable attenuator was designed and demonstrated. The optical variable attenuation is achieved in Mach-Zehnder interferometric configuration through all-optical modulation of sol-gel waveguide phase shifters. A 2 x 2 optical switch based on multimode interference (MMI) waveguide structure is proposed in the dissertation. The schematic configuration of the optical switch consists of a cascade of two identical MMIs with two all-optical controlled phase shifters realized by using the photochromic sol-gel material. The cross or bar switch state of the optical switch is determined by the phase difference between the two sol-gel waveguide phase shifters. An all-optical tunable filter is designed and its feasibility demonstrated by using the sol-gel photochromic material. Except for the phase change demonstrated on sol-gel waveguide phase shifters, dynamic gratings were observed on sol-gel film when exposed to two interference beams. This reveals the possibility of realizing Bragg grating-based tunable filters. The schematic configuration of proposed tunable filters consists of a single straight waveguide embedded with a sol-gel waveguide. The wavelength tuning of the tunable filters is accomplished by varying the grating period.

Self-controlled concurrent feedback facilitates the learning of the final approach phase in a fixed-base flight simulator.

PubMed

Huet, Michaël; Jacobs, David M; Camachon, Cyril; Goulon, Cedric; Montagne, Gilles

2009-12-01

This study (a) compares the effectiveness of different types of feedback for novices who learn to land a virtual aircraft in a fixed-base flight simulator and (b) analyzes the informational variables that learners come to use after practice. An extensive body of research exists concerning the informational variables that allow successful landing. In contrast, few studies have examined how the attention of pilots can be directed toward these sources of information. In this study, 15 participants were asked to land a virtual Cessna 172 on 245 trials while trying to follow the glide-slope area as accurately as possible. Three groups of participants practiced under different feedback conditions: with self-controlled concurrent feedback (the self-controlled group), with imposed concurrent feedback (the yoked group), or without concurrent feedback (the control group). The self-controlled group outperformed the yoked group, which in turn outperformed the control group. Removing or manipulating specific sources of information during transfer tests had different effects for different individuals. However, removing the cockpit from the visual scene had a detrimental effect on the performance of the majority of the participants. Self-controlled concurrent feedback helps learners to more quickly attune to the informational variables that allow them to control the aircraft during the approach phase. Knowledge concerning feedback schedules can be used for the design of optimal practice methods for student pilots, and knowledge about the informational variables used by expert performers has implications for the design of cockpits and runways that facilitate the detection of these variables.

The education of attention as explanation of variability of practice effects: learning the final approach phase in a flight simulator.

PubMed

Huet, Michaël; Jacobs, David M; Camachon, Cyril; Missenard, Olivier; Gray, Rob; Montagne, Gilles

2011-12-01

The present study reports two experiments in which a total of 20 participants without prior flight experience practiced the final approach phase in a fixed-base simulator. All participants received self-controlled concurrent feedback during 180 practice trials. Experiment 1 shows that participants learn more quickly under variable practice conditions than under constant practice conditions. This finding is attributed to the education of attention to the more useful informational variables: Variability of practice reduces the usefulness of initially used informational variables, which leads to a quicker change in variable use, and hence to a larger improvement in performance. In the practice phase of Experiment 2 variability was selectively applied to some experimental factors but not to others. Participants tended to converge toward the variables that were useful in the specific conditions that they encountered during practice. This indicates that an explanation for variability of practice effects in terms of the education of attention is a useful alternative to traditional explanations based on the notion of the generalized motor program and to explanations based on the notions of noise and local minima.

New approach to control the methanogenic reactor of a two-phase anaerobic digestion system.

PubMed

von Sachs, Jürgen; Meyer, Ulrich; Rys, Paul; Feitkenhauer, Heiko

2003-03-01

A new control strategy for the methanogenic reactor of a two-phase anaerobic digestion system has been developed and successfully tested on the laboratory scale. The control strategy serves the purpose to detect inhibitory effects and to achieve good conversion. The concept is based on the idea that volatile fatty acids (VFA) can be measured in the influent of the methanogenic reactor by means of titration. Thus, information on the output (methane production) and input of the methanogenic reactor is available, and a (carbon) mass balance can be obtained. The control algorithm comprises a proportional/integral structure with the ratio of (a) the methane production rate measured online and (b) a maximum methane production rate expected (derived from the stoichiometry) as a control variable. The manipulated variable is the volumetric feed rate. Results are shown for an experiment with VFA (feed) concentration ramps and for experiments with sodium chloride as inhibitor.

Autonomic neural control of dynamic cerebral autoregulation in humans

NASA Technical Reports Server (NTRS)

Zhang, Rong; Zuckerman, Julie H.; Iwasaki, Kenichi; Wilson, Thad E.; Crandall, Craig G.; Levine, Benjamin D.

2002-01-01

BACKGROUND: The purpose of the present study was to determine the role of autonomic neural control of dynamic cerebral autoregulation in humans. METHODS AND RESULTS: We measured arterial pressure and cerebral blood flow (CBF) velocity in 12 healthy subjects (aged 29+/-6 years) before and after ganglion blockade with trimethaphan. CBF velocity was measured in the middle cerebral artery using transcranial Doppler. The magnitude of spontaneous changes in mean blood pressure and CBF velocity were quantified by spectral analysis. The transfer function gain, phase, and coherence between these variables were estimated to quantify dynamic cerebral autoregulation. After ganglion blockade, systolic and pulse pressure decreased significantly by 13% and 26%, respectively. CBF velocity decreased by 6% (P<0.05). In the very low frequency range (0.02 to 0.07 Hz), mean blood pressure variability decreased significantly (by 82%), while CBF velocity variability persisted. Thus, transfer function gain increased by 81%. In addition, the phase lead of CBF velocity to arterial pressure diminished. These changes in transfer function gain and phase persisted despite restoration of arterial pressure by infusion of phenylephrine and normalization of mean blood pressure variability by oscillatory lower body negative pressure. CONCLUSIONS: These data suggest that dynamic cerebral autoregulation is altered by ganglion blockade. We speculate that autonomic neural control of the cerebral circulation is tonically active and likely plays a significant role in the regulation of beat-to-beat CBF in humans.

Gate sequence for continuous variable one-way quantum computation

PubMed Central

Su, Xiaolong; Hao, Shuhong; Deng, Xiaowei; Ma, Lingyu; Wang, Meihong; Jia, Xiaojun; Xie, Changde; Peng, Kunchi

2013-01-01

Measurement-based one-way quantum computation using cluster states as resources provides an efficient model to perform computation and information processing of quantum codes. Arbitrary Gaussian quantum computation can be implemented sufficiently by long single-mode and two-mode gate sequences. However, continuous variable gate sequences have not been realized so far due to an absence of cluster states larger than four submodes. Here we present the first continuous variable gate sequence consisting of a single-mode squeezing gate and a two-mode controlled-phase gate based on a six-mode cluster state. The quantum property of this gate sequence is confirmed by the fidelities and the quantum entanglement of two output modes, which depend on both the squeezing and controlled-phase gates. The experiment demonstrates the feasibility of implementing Gaussian quantum computation by means of accessible gate sequences.

Primary and submovement control of aiming in C6 tetraplegics following posterior deltoid transfer

PubMed Central

2014-01-01

Background Upper limb motor control in fast, goal-directed aiming is altered in tetraplegics following posterior-deltoid musculotendinous transfer. Specifically, movements have similar end-point accuracy but longer duration and lower peak velocity than those of age-matched, neurotypical controls. Here, we examine in detail the interplay between primary movement and submovement phases in five C6 tetraplegic and five control participants. Methods Aiming movements were performed in two directions (20 cm away or toward), with or without vision. Trials that contained a submovement phase (i.e., discontinuity in velocity, acceleration or jerk) were identified. Discrete kinematic variables were then extracted on the primary and submovements phases. Results The presence of submovements did not differ between the tetraplegic (68%) and control (57%) groups, and almost all submovements resulted from acceleration and jerk discontinuities. Tetraplegics tended to make a smaller amplitude primary movement, which had lower peak velocity and greater spatial variability at peak velocity. This was followed by a larger amplitude and longer duration secondary submovement. Peak velocity of primary movement was not related to submovement incidence. Together, the primary and submovement phases of both groups were equally effective in reducing end-point error. Conclusions C6 tetraplegic participants exhibit some subtle differences in measures of motor behaviour compared to control participants, but importantly feedforward and feedback processes work effectively in combination to achieve accurate goal-directed aiming. PMID:25055852

Optimized PID control of depth of hypnosis in anesthesia.

PubMed

Padula, Fabrizio; Ionescu, Clara; Latronico, Nicola; Paltenghi, Massimiliano; Visioli, Antonio; Vivacqua, Giulio

2017-06-01

This paper addresses the use of proportional-integral-derivative controllers for regulating the depth of hypnosis in anesthesia by using propofol administration and the bispectral index as a controlled variable. In fact, introducing an automatic control system might provide significant benefits for the patient in reducing the risk for under- and over-dosing. In this study, the controller parameters are obtained through genetic algorithms by solving a min-max optimization problem. A set of 12 patient models representative of a large population variance is used to test controller robustness. The worst-case performance in the considered population is minimized considering two different scenarios: the induction case and the maintenance case. Our results indicate that including a gain scheduling strategy enables optimal performance for induction and maintenance phases, separately. Using a single tuning to address both tasks may results in a loss of performance up to 102% in the induction phase and up to 31% in the maintenance phase. Further on, it is shown that a suitably designed low-pass filter on the controller output can handle the trade-off between the performance and the noise effect in the control variable. Optimally tuned PID controllers provide a fast induction time with an acceptable overshoot and a satisfactory disturbance rejection performance during maintenance. These features make them a very good tool for comparison when other control algorithms are developed. Copyright © 2017 Elsevier B.V. All rights reserved.

Movement variability and skill level of various throwing techniques.

PubMed

Wagner, Herbert; Pfusterschmied, Jürgen; Klous, Miriam; von Duvillard, Serge P; Müller, Erich

2012-02-01

In team-handball, skilled athletes are able to adapt to different game situations that may lead to differences in movement variability. Whether movement variability affects the performance of a team-handball throw and is affected by different skill levels or throwing techniques has not yet been demonstrated. Consequently, the aims of the study were to determine differences in performance and movement variability for several throwing techniques in different phases of the throwing movement, and of different skill levels. Twenty-four team-handball players of different skill levels (n=8) performed 30 throws using various throwing techniques. Upper body kinematics was measured via an 8 camera Vicon motion capture system and movement variability was calculated. Results indicated an increase in movement variability in the distal joint movements during the acceleration phase. In addition, there was a decrease in movement variability in highly skilled and skilled players in the standing throw with run-up, which indicated an increase in the ball release speed, which was highest when using this throwing technique. We assert that team-handball players had the ability to compensate an increase in movement variability in the acceleration phase to throw accurately, and skilled players were able to control the movement, although movement variability decreased in the standing throw with run-up. Copyright © 2011 Elsevier B.V. All rights reserved.

Relationship between glycaemic variability and hyperglycaemic clamp-derived functional variables in (impending) type 1 diabetes.

PubMed

Van Dalem, Annelien; Demeester, Simke; Balti, Eric V; Decochez, Katelijn; Weets, Ilse; Vandemeulebroucke, Evy; Van de Velde, Ursule; Walgraeve, An; Seret, Nicole; De Block, Christophe; Ruige, Johannes; Gillard, Pieter; Keymeulen, Bart; Pipeleers, Daniel G; Gorus, Frans K

2015-12-01

We examined whether measures of glycaemic variability (GV), assessed by continuous glucose monitoring (CGM) and self-monitoring of blood glucose (SMBG), can complement or replace measures of beta cell function and insulin action in detecting the progression of preclinical disease to type 1 diabetes. Twenty-two autoantibody-positive (autoAb(+)) first-degree relatives (FDRs) of patients with type 1 diabetes who were themselves at high 5-year risk (50%) for type 1 diabetes underwent CGM, a hyperglycaemic clamp test and OGTT, and were followed for up to 31 months. Clamp variables were used to estimate beta cell function (first-phase [AUC5-10 min] and second-phase [AUC120-150 min] C-peptide release) combined with insulin resistance (glucose disposal rate; M 120-150 min). Age-matched healthy volunteers (n = 20) and individuals with recent-onset type 1 diabetes (n = 9) served as control groups. In autoAb(+) FDRs, M 120-150 min below the 10th percentile (P10) of controls achieved 86% diagnostic efficiency in discriminating between normoglycaemic FDRs and individuals with (impending) dysglycaemia. M 120-150 min outperformed AUC5-10 min and AUC120-150 min C-peptide below P10 of controls, which were only 59-68% effective. Among GV variables, CGM above the reference range was better at detecting (impending) dysglycaemia than elevated SMBG (77-82% vs 73% efficiency). Combined CGM measures were equally efficient as M 120-150 min (86%). Daytime GV variables were inversely correlated with clamp variables, and more strongly with M 120-150 min than with AUC5-10 min or AUC120-150 min C-peptide. CGM-derived GV and the glucose disposal rate, reflecting both insulin secretion and action, outperformed SMBG and first- or second-phase AUC C-peptide in identifying FDRs with (impending) dysglycaemia or diabetes. Our results indicate the feasibility of developing minimally invasive CGM-based criteria for close metabolic monitoring and as outcome measures in trials.

Stroke patients' functions in personal activities of daily living in relation to sleep and socio-demographic and clinical variables in the acute phase after first-time stroke and at six months of follow-up.

PubMed

Bakken, Linda N; Kim, Hesook S; Finset, Arnstein; Lerdal, Anners

2012-07-01

To explore first-time stroke patients' degree of independence in activities of daily life in relation to sleep and other essential variables that might influence activities of daily life. Sleep has received little attention in rehabilitation of activities of daily life in stroke patients. This is a longitudinal survey and observational study design from the acute phase to six months poststroke. First-time stroke patients (n = 90) were recruited from two hospitals in eastern Norway in 2007 and 2008. Data were collected by survey interview, medical records and wrist actigraphy in the first two weeks at the hospital and at six months of follow-up. Actigraph measures patient activity and estimates sleep during the day and night. Linear regression showed that high dependence in personal activities of daily living was directly related to low estimated sleep time at night and higher estimated sleep during the day in the acute phase, controlling for socio-demographic and clinical variables. Furthermore, high estimated numbers of awakenings in the acute phase were related to lower activities of daily life functioning at six months of follow-up after controlling for socio-demographic and clinical variables. Stronger pain and a lower physical functioning showed direct relationships with lower independency level of in activities of daily life both in the acute phase and after six months. Sleep patterns in the acute phase may influence the patients' activities of daily life functioning up to six months poststroke. Furthermore, pain in the acute phase may influence the level of activities of daily life functioning in stroke patients. Nurses should pay attention to stroke patients' sleep quality and pain in the rehabilitation period after a stroke. Facilitating good sleep conditions and screening for pain should be an integral part of the rehabilitation programme. © 2012 Blackwell Publishing Ltd.

An experimental study of human pilot's scanning behavior

NASA Technical Reports Server (NTRS)

Washizu, K.; Tanaka, K.; Osawa, T.

1982-01-01

The scanning behavior and the control behavior of the pilot who manually controls the two-variable system, which is the most basic one of multi-variable systems are investigated. Two control tasks which simulate the actual airplane attitude and airspeed control were set up. In order to simulate the change of the situation where the pilot is placed, such as changes of flight phase, mission and others, the subject was requested to vary the weightings, as his control strategy, upon each task. Changes of human control dynamics and his canning properties caused by the modification of the situation were investigated. By making use of the experimental results, the optimal model of the control behavior and the scanning behavior of the pilot in the two-variable system is proposed from the standpoint of making the performance index minimal.

Finite State Control of a Variable Impedance Hybrid Neuroprosthesis for Locomotion after Paralysis

PubMed Central

Bulea, Thomas C.; Kobetic, R.; Audu, M.L.; Schnellenberger, J.; Triolo, R.J.

2013-01-01

We have previously reported on a novel variable impedance knee mechanism (VIKM). The VIKM was designed as a component of a hybrid neuroprosthesis to regulate knee flexion. The hybrid neuroprosthesis is a device that uses a controllable brace to support the body against collapse while stimulation provides power for movement. The hybrid neuroprosthesis requires a control system to coordinate the actions of the VIKM with the stimulation system; the development and evaluation of such a controller is presented. Brace mounted sensors and a baseline open loop stimulation pattern are utilized as control signals to activate the VIKM during stance phase while simultaneously modulating muscle stimulation in an on-off fashion. The objective is twofold: reduce the amount of stimulation necessary for walking while simultaneously restoring more biologically correct knee motion during stance using the VIKM. Custom designed hardware and software components were developed for controller implementation. The VIKM hybrid neuroprosthesis (VIKM-HNP) was evaluated during walking in one participant with thoracic level spinal cord injury. In comparison to walking with functional neuromuscular stimulation (FNS) alone, the VIKM-HNP restored near normal stance phase knee flexion during loading response and pre-swing phases while decreasing knee extensor stimulation by up to 40%. PMID:23193320

Independently variable phase and stroke control for a double acting Stirling engine

DOEpatents

Berchowitz, David M.

1983-01-01

A phase and stroke control apparatus for the pistons of a Stirling engine includes a ring on the end of each piston rod in which a pair of eccentrics is arranged in series, torque transmitting relationship. The outer eccentric is rotatably mounted in the ring and is rotated by the orbiting ring; the inner eccentric is mounted on an output shaft. The two eccentrics are mounted for rotation together within the ring during normal operation. A device is provided for rotating one eccentric with respect to another to change the effective eccentricity of the pair of eccentrics. A separately controlled phase adjustment is provided to null the phase change introduced by the change in the orientation of the outer eccentric, and also to enable the phase of the pistons to be changed independently of the stroke change.

The effect of exercise hypertrophy and disuse atrophy on muscle contractile properties: a mechanomyographic analysis.

PubMed

Than, Christian; Tosovic, Danijel; Seidl, Laura; Mark Brown, J

2016-12-01

To determine whether mechanomyographic (MMG) determined contractile properties of the biceps brachii change during exercise-induced hypertrophy and subsequent disuse atrophy. Healthy subjects (mean ± SD, 23.7 ± 2.6 years, BMI 21.8 ± 2.4, n = 19) performed unilateral biceps curls (9 sets × 12 repetitions, 5 sessions per week) for 8 weeks (hypertrophic phase) before ceasing exercise (atrophic phase) for the following 8 weeks (non-dominant limb; treatment, dominant limb; control). MMG measures of muscle contractile properties (contraction time; T c , maximum displacement; D max , contraction velocity; V c ), electromyographic (EMG) measures of muscle fatigue (median power frequency; MPF), strength measures (maximum voluntary contraction; MVC) and measures of muscle thickness (ultrasound) were obtained. Two-way repeated measures ANOVA showed significant differences (P < 0.05) between treatment and control limbs. During the hypertrophic phase treatment MVC initially declined (weeks 1-3), due to fatigue (decline in MPF), followed by improvement against control during weeks 6-8. Between weeks 5 and 8 treatment, muscle thickness was greater than control, reflecting gross hypertrophy. MMG variables Dmax (weeks 2, 7) and Vc (weeks 7, 8) declined. During the atrophic phase, MVC (weeks 9-12) and muscle thickness (weeks 9, 10) initially remained high before declining to control levels, reflecting gross atrophy. MMG variables D max (weeks 9, 14) and V c (weeks 9, 14, 15) also declined during the atrophic phase. No change in T c was found throughout the hypertrophic or atrophic phases. MMG detects changes in contractile properties during stages of exercise-induced hypertrophy and disuse atrophy suggesting its applicability as a clinical tool in musculoskeletal rehabilitation.

Control system design for the MOD-5A 7.3 mW wind turbine generator

NASA Technical Reports Server (NTRS)

Barton, Robert S.; Hosp, Theodore J.; Schanzenbach, George P.

1995-01-01

This paper provides descriptions of the requirements analysis, hardware development and software development phases of the Control System design for the MOD-5A 7.3 mW Wind Turbine Generator. The system, designed by General Electric Company, Advanced Energy Programs Department, under contract DEN 3-153 with NASA Lewis Research Center and DOE, provides real time regulation of rotor speed by control of both generator torque and rotor torque. A variable speed generator system is used to provide both airgap torque control and reactive power control. The wind rotor is designed with segmented ailerons which are positioned to control blade torque. The central component of the control system, selected early in the design process, is a programmable controller used for sequencing, alarm monitoring, communication, and real time control. Development of requirements for use of aileron controlled blades and a variable speed generator required an analytical simulation that combined drivetrain, tower and blade elastic modes with wind disturbances and control behavior. An orderly two phase plan was used for controller software development. A microcomputer based turbine simulator was used to facilitate hardware and software integration and test.

Effect of eight weeks of upper-body plyometric training during the competitive season on professional female volleyball players.

PubMed

Valades, David; Palao, José M; Femia, Pedro; Ureña, Aurelio

2017-07-25

The purpose of this study was to assess the effect of incorporating specific upper-body plyometric training for the spike into the competitive season of a women's professional volleyball team. A professional team from the Spanish first division participated in the study. An A-B-A' quasi-experimental design with experimental and control groups was used. The independent variable was the upper-body plyometric training for eight weeks during the competitive season. The dependent variables were the spiked ball's speed (Km/h); the player's body weight (Kg), BMI (Kg/m2), and muscle percentage in arms (%); 1 repetition maximum (1RM) in the bench press (Kg); 1RM in the pullover (Kg); and overhead medicine ball throws of 1, 2, 3, 4, and 5 kg (m). Inter-player and inter-group statistical analyses of the results were carried out (Wilcoxon test and linear regression model). The experimental group significantly improved their spike speed 3.8% from phase A to phase B, and they maintained this improvement after the retention phase. No improvements were found in the control group. The experimental group presented a significant improvement from phase A to phase B in dominant arm muscle area (+10.8%), 1RM for the bench press (+8.41%), 1RM for the pullover (+14.75%), and overhead medicine ball throws with 1 kg (+7.19%), 2 kg (+7.69%), and 3 kg (+5.26%). The control group did not present differences in these variables. Data showed the plyometric exercises that were tested could be used by performance-level volleyball teams to improve spike speed. The experimental group increased their upper-body maximal strength, their power application, and spike speed.

RF power recovery feedback circulator

DOEpatents

Sharamentov, Sergey I [Bolingbrook, IL

2011-03-29

A device and method for improving the efficiency of RF systems having a Reflective Load. In the preferred embodiment, Reflected Energy from a superconducting resonator of a particle accelerator is reintroduced to the resonator after the phase of the Reflected Energy is aligned with the phase of the Supply Energy from a RF Energy Source. In one embodiment, a Circulator is used to transfer Reflected Energy from the Reflective Load into a Phase Adjuster which aligns the phase of the Reflected Energy with that of the Supply Energy. The phase-aligned energy is then combined with the Supply Energy, and reintroduced into the Reflective Load. In systems having a constant phase shift, the Phase Adjuster may be designed to shift the phase of the Reflected Energy by a constant amount using a Phase Shifter. In systems having a variety (variable) phase shifts, a Phase Shifter controlled by a phase feedback loop comprising a Phase Detector and a Feedback Controller to account for the various phase shifts is preferable.

Novel Control Scheme of Power Assisted Wheelchair for Preventing Overturn (Part II)-Variable Assistance Ratio Control Based on Estimation of Center-of-Gravity Angle and Phase Plane-

NASA Astrophysics Data System (ADS)

Hata, Naoki; Seki, Hirokazu; Koyasu, Yuichi; Hori, Yoichi

Aged people and disabled people who have difficulty in walking are increasing. As one of mobility support, significance of a power assisted wheelchair which assists driving force using electric motors and spreads their living areas has been enhanced. However, the increased driving force often causes a dangerous overturn of wheelchair. This paper proposes a novel control method to prevent power assisted wheelchair from overturning. The man-wheelchair system can be regarded as an inverse pendulum model when the front wheels are rising. The center-of-gravity (COG) angle of the model is the most important information directly-linked to overturn. Behavior of the system can be analyzed using phase plane as shown in this paper. The COG angle cannot be directly measured using a sensor, therefore, COG observer based on its velocity is proposed. On the basis of the analysis on phase plane, a novel control method with variable assistance ratio to prevent a dangerous overturn is proposed. The effectiveness of the proposed method is verified by the practical experiments on the flat ground and uphill slope.

Timing matters: change depends on the stage of treatment in cognitive behavioral therapy for panic disorder with agoraphobia.

PubMed

Gloster, Andrew T; Klotsche, Jens; Gerlach, Alexander L; Hamm, Alfons; Ströhle, Andreas; Gauggel, Siegfried; Kircher, Tilo; Alpers, Georg W; Deckert, Jürgen; Wittchen, Hans-Ulrich

2014-02-01

The mechanisms of action underlying treatment are inadequately understood. This study examined 5 variables implicated in the treatment of panic disorder with agoraphobia (PD/AG): catastrophic agoraphobic cognitions, anxiety about bodily sensations, agoraphobic avoidance, anxiety sensitivity, and psychological flexibility. The relative importance of these process variables was examined across treatment phases: (a) psychoeducation/interoceptive exposure, (b) in situ exposure, and (c) generalization/follow-up. Data came from a randomized controlled trial of cognitive behavioral therapy for PD/AG (n = 301). Outcomes were the Panic and Agoraphobia Scale (Bandelow, 1995) and functioning as measured in the Clinical Global Impression scale (Guy, 1976). The effect of process variables on subsequent change in outcome variables was calculated using bivariate latent difference score modeling. Change in panic symptomatology was preceded by catastrophic appraisal and agoraphobic avoidance across all phases of treatment, by anxiety sensitivity during generalization/follow-up, and by psychological flexibility during exposure in situ. Change in functioning was preceded by agoraphobic avoidance and psychological flexibility across all phases of treatment, by fear of bodily symptoms during generalization/follow-up, and by anxiety sensitivity during exposure. The effects of process variables on outcomes differ across treatment phases and outcomes (i.e., symptomatology vs. functioning). Agoraphobic avoidance and psychological flexibility should be investigated and therapeutically targeted in addition to cognitive variables. PsycINFO Database Record (c) 2014 APA, all rights reserved.

RF MEMS and Their Applications in NASA's Space Communication Systems

NASA Technical Reports Server (NTRS)

Williams, W. Daniel; Ponchak, George E.; Simons, Rainee N.; Zaman, Afroz; Kory, Carol; Wintucky, Edwin; Wilson, Jeffrey D.; Scardelletti, Maximilian; Lee, Richard; Nguyen, Hung

2001-01-01

Radio frequency (RF) and microwave communication systems rely on frequency, amplitude, and phase control circuits to efficiently use the available spectrum. Phase control circuits are required for electronically scanning phase array antennas that enable radiation pattern shaping, scanning, and hopping. Two types of phase shifters, which are the phase control circuits, are most often used. The first is comprised of two circuits with different phase characteristics such as two transmission lines of different lengths or a high pass and low pass filter and a switch that directs the RF power through one of the two circuits. Alternatively, a variable capacitor, or varactor, is used to change the effective electrical path length of a transmission line, which changes the phase characteristics. Filter banks are required for the diplexer at the front end of wide band communication satellites. These filters greatly increase the size and mass of the RF/microwave systems, but smaller diplexers may be made with a low loss varactor or a group of capacitors, a switch and an inductor.

Recognizing and Reducing Analytical Errors and Sources of Variation in Clinical Pathology Data in Safety Assessment Studies.

PubMed

Schultze, A E; Irizarry, A R

2017-02-01

Veterinary clinical pathologists are well positioned via education and training to assist in investigations of unexpected results or increased variation in clinical pathology data. Errors in testing and unexpected variability in clinical pathology data are sometimes referred to as "laboratory errors." These alterations may occur in the preanalytical, analytical, or postanalytical phases of studies. Most of the errors or variability in clinical pathology data occur in the preanalytical or postanalytical phases. True analytical errors occur within the laboratory and are usually the result of operator or instrument error. Analytical errors are often ≤10% of all errors in diagnostic testing, and the frequency of these types of errors has decreased in the last decade. Analytical errors and increased data variability may result from instrument malfunctions, inability to follow proper procedures, undetected failures in quality control, sample misidentification, and/or test interference. This article (1) illustrates several different types of analytical errors and situations within laboratories that may result in increased variability in data, (2) provides recommendations regarding prevention of testing errors and techniques to control variation, and (3) provides a list of references that describe and advise how to deal with increased data variability.

Plasma 17-alpha-OH-progesterone in female workers exposed to urban pollutants.

PubMed

Ciarrocca, M; Cerratti, D; Capozzella, A; Rosati, M V; Anzani, M F; Bernardini, A; Casale, T; Pimpinella, B; Tomei, G; Monti, C; Tomao, E; Tomei, F

2006-01-01

The aim of this study is to evaluate whether occupational exposure to urban pollutants could cause alteration in plasma 17-alpha-OH-P levels in female workers. After excluding the subjects with the principal confounding factors, traffic police and controls were matched by age, working life, age of menarche, menstrual cycle day, BMI, drinking habits, habitual consumption of soy and Italian coffee. 68 traffic police and 82 controls (7th day; follicular phase of the ovarian cycle), 37 traffic police and 20 controls (21st day; lutheal phase of the ovarian cycle) were included in the study and matched for the above mentioned variables. In follicular and lutheal phase of ovarian cycle, 17-alpha-OH-P mean levels and the distribution of 17-alpha-OH-P values were significantly higher in traffic police vs. controls. A higher instance of mental health disorders in traffic police vs. controls was found, although the difference was not significant. Considering that the potential confounding effect of extraneous factors was controlled by restricting the study population and by matching traffic police vs. controls on the above mentioned variables, our results suggest that occupational exposure to urban pollutants may alter plasma 17-alpha-OH-P concentrations. 17-alpha-OH-P could be used in an occupational setting as an early biomarker of exposure to urban pollutants, valuable for a group, even before the onset of related pathologies.

A feedback control for the advanced launch system

NASA Technical Reports Server (NTRS)

Seywald, Hans; Cliff, Eugene M.

1991-01-01

A robust feedback algorithm is presented for a near-minimum-fuel ascent of a two-stage launch vehicle operating in the equatorial plane. The development of the algorithm is based on the ideas of neighboring optimal control and can be derived into three phases. In phase 1, the formalism of optimal control is employed to calculate fuel-optimal ascent trajectories for a simple point-mass model. In phase 2, these trajectories are used to numerically calculate gain functions of time for the control(s), the total flight time, and possibly, for other variables of interest. In phase 3, these gains are used to determine feedback expressions for the controls associated with a more realistic model of a launch vehicle. With the Advanced Launch System in mind, all calculations are performed on a two-stage vehicle with fixed thrust history, but this restriction is by no means important for the approach taken. Performance and robustness of the algorithm is found to be excellent.

Effect of shrinkage on isothermal drying behavior of 2-phase olive mill waste

USDA-ARS?s Scientific Manuscript database

The objective of this study was to determine the drying behavior of 2-phase olive mill waste (2POMW) under isothermal microwave-convection drying conditions. 2POMW samples were dried in a thin layer in a variable-power pilot microwave oven with impinging air, using a feedback controller to maintain...

Advanced supersonic propulsion study, phase 3

NASA Technical Reports Server (NTRS)

Howlett, R. A.; Johnson, J.; Sabatella, J.; Sewall, T.

1976-01-01

The variable stream control engine is determined to be the most promising propulsion system concept for advanced supersonic cruise aircraft. This concept uses variable geometry components and a unique throttle schedule for independent control of two flow streams to provide low jet noise at takeoff and high performance at both subsonic and supersonic cruise. The advanced technology offers a 25% improvement in airplane range and an 8 decibel reduction in takeoff noise, relative to first generation supersonic turbojet engines.

Multivariate areal analysis of the impact and efficiency of the family planning programme in peninsular Malaysia.

PubMed

Tan Boon Ann

1987-06-01

The findings of the final phase of a 3-phase multivariate areal analysis study undertaken by the Economic and Social Commission for Asia and the Pacific (ESCAP) in 5 countries of the Asian and Pacific Region, including Malaysia, to examine the impact of family planning programs on fertility and reproduction are reported. The study used Malaysia's administrative district as the unit of analysis because the administration and implementation of socioeconomic development activities, as well as the family planning program, depend to a large extent on the decisions of local organizations at the district or state level. In phase 1, existing program and nonprogram data were analyzed using the multivariate technique to separate the impact of the family planning program net of other developmental efforts. The methodology in the 2nd phase consisted of in-depth investigation of selected areas in order to discern the dynamics and determinants of efficiency. The insights gained in phase 2 regarding dynamics of performance were used in phase 3 to refine the input variables of the phase 1 model. Thereafter, the phase 1 analysis was repeated. Insignificant variables and factors were trimmed in order to present a simplified model for studying the impact of environmental, socioeconomic development, family planning programs, and related factors on fertility. The inclusion of a set of family planning program and development variables in phase 3 increased the predictive power of the impact model. THe explained variance for total fertility rate (TFR) of women under 30 years increased from 71% in phase 1 to 79%. It also raised the explained variance of the efficiency model from 34% to 70%. For women age 30 years and older, their TFR was affected directly by the ethnic composition variable (.76), secondary educational status (-.45), and modern nonagricultural occupation (.42), among others. When controlled for other socioeconomic development and environmental indicators, the nonagricultural activities had a positive direct effect on TFR. No direct effects were found to come from other socioeconomic development indicators, once these factors were controlled. The 3 factors that had direct effects on the fertility of women below age 30 were ethnic composition (.33), contraceptive pevalence (-.32), and secondary educational status (-.25). Other family planning program variables (contraceptive knowledge) and socioeconomic development indicators (exposure to modernization as measured by television ownership and health/living conditions as measured by infant mortality rate) affected fertility significantly but indirectly.

A kinematic flexure-based mechanism for precise parallel motion for the Hertz Variable-delay Polarization Modulator (VPM)

NASA Astrophysics Data System (ADS)

Voellmer, G. M.; Chuss, D. T.; Jackson, M.; Krejny, M.; Moseley, S. H.; Novak, G.; Wollack, E. J.

2006-06-01

We describe the design and construction of a Variable-delay Polarization Modulator (VPM) that has been built and integrated into the Hertz ground-based, submillimeter polarimeter at the SMTO on Mt. Graham in Arizona. VPMs allow polarization modulation by controlling the phase difference between two linear, orthogonal polarizations. This is accomplished by utilizing a grid-mirror pair with a controlled separation. The size of the gap between the mirror and the polarizing grid determines the amount of the phase difference. This gap must be parallel to better than 1% of the wavelength. The necessity of controlling the phase of the radiation across this device drives the two novel features of the VPM. First, a novel, kinematic, flexure is employed that passively maintains the parallelism of the mirror and the grid to 1.5 μm over a 150 mm diameter, with a 400 μm throw. A single piezoceramic actuator is used to modulate the gap, and a capacitive sensor provides position feedback for closed-loop control. Second, the VPM uses a grid flattener that highly constrains the planarity of the polarizing grid. In doing so, the phase error across the device is minimized. Engineering results from the deployment of this device in the Hertz instrument April 2006 at the Submillimeter Telescope Observatory (SMTO) in Arizona are presented.

Development of speech motor control: lip movement variability.

PubMed

Schötz, Susanne; Frid, Johan; Löfqvist, Anders

2013-06-01

This study examined variability of lip movements across repetitions of the same utterance as a function of age in Swedish speakers. The specific purpose was to extend earlier findings by examining variability in both phase and amplitude. Subjects were 50 typically developed native Swedish children and adults (28 females, 22 males, aged 5 to 31 yr). Lip movements were recorded during 15 to 20 repetitions of a short Swedish phrase using three-dimensional articulography. After correction for head movements, the kinematic records were expressed in a maxilla-based coordinate system. Movement onset and offset of the utterance were identified using kinematic landmarks. The Euclidean distance between receivers on the upper and lower lips was calculated and subjected to functional data analysis to assess both phase and amplitude variability. Results show a decrease in both indices as a function of age, with a greater reduction of amplitude variability. There was no difference between males and females for either index. The two indices were moderately correlated with each other, suggesting that they capture different aspects of speech production. Utterance duration also decreased with age, but variability was unrelated to duration. The standard deviation of utterance duration also decreased with age. The present results thus suggest that age related changes in speech motor control continue up until 30 years of age.

Kinetic measures of restabilisation during volitional stepping reveal age-related alterations in the control of mediolateral dynamic stability.

PubMed

Singer, Jonathan C; McIlroy, William E; Prentice, Stephen D

2014-11-07

Research examining age-related changes in dynamic stability during stepping has recognised the importance of the restabilisation phase, subsequent to foot-contact. While regulation of the net ground reaction force (GRFnet) line of action is believed to influence dynamic stability during steady-state locomotion, such control during restabilisation remains unknown. This work explored the origins of age-related decline in mediolateral dynamic stability by examining the line of action of GRFnet relative to the centre of mass (COM) during restabilisation following voluntary stepping. Healthy younger and older adults (n=20 per group) performed three single-step tasks (varying speed and step placement), altering the challenge to stability control. Age-related differences in magnitude and intertrial variability of the angle of divergence of GRFnet line of action relative to the COM were quantified, along with the peak mediolateral and vertical GRFnet components. The angle of divergence was further examined at discrete points during restabilisation, to uncover events of potential importance to stability control. Older adults exhibited a reduced angle of divergence throughout restabilisation. Temporal and spatial constraints on stepping increased the magnitude and intertrial variability of the angle of divergence, although not differentially among the older adults. Analysis of the time-varying angle of divergence revealed age-related reductions in magnitude, with increases in timing and intertrial timing variability during the later phase of restabilisation. This work further supports the idea that age-related challenges in lateral stability control emerge during restabilisation. Age-related alterations during the later phase of restabilisation may signify challenges with reactive control. Copyright © 2014 Elsevier Ltd. All rights reserved.

Phase transitions in distributed control systems with multiplicative noise

NASA Astrophysics Data System (ADS)

Allegra, Nicolas; Bamieh, Bassam; Mitra, Partha; Sire, Clément

2018-01-01

Contemporary technological challenges often involve many degrees of freedom in a distributed or networked setting. Three aspects are notable: the variables are usually associated with the nodes of a graph with limited communication resources, hindering centralized control; the communication is subject to noise; and the number of variables can be very large. These three aspects make tools and techniques from statistical physics particularly suitable for the performance analysis of such networked systems in the limit of many variables (analogous to the thermodynamic limit in statistical physics). Perhaps not surprisingly, phase-transition like phenomena appear in these systems, where a sharp change in performance can be observed with a smooth parameter variation, with the change becoming discontinuous or singular in the limit of infinite system size. In this paper, we analyze the so called network consensus problem, prototypical of the above considerations, that has previously been analyzed mostly in the context of additive noise. We show that qualitatively new phase-transition like phenomena appear for this problem in the presence of multiplicative noise. Depending on dimensions, and on the presence or absence of a conservation law, the system performance shows a discontinuous change at a threshold value of the multiplicative noise strength. In the absence of the conservation law, and for graph spectral dimension less than two, the multiplicative noise threshold (the stability margin of the control problem) is zero. This is reminiscent of the absence of robust controllers for certain classes of centralized control problems. Although our study involves a ‘toy’ model, we believe that the qualitative features are generic, with implications for the robust stability of distributed control systems, as well as the effect of roundoff errors and communication noise on distributed algorithms.

V/STOL propulsion control analysis: Phase 2, task 5-9

NASA Technical Reports Server (NTRS)

1981-01-01

Typical V/STOL propulsion control requirements were derived for transition between vertical and horizontal flight using the General Electric RALS (Remote Augmented Lift System) concept. Steady-state operating requirements were defined for a typical Vertical-to-Horizontal transition and for a typical Horizontal-to-Vertical transition. Control mode requirements were established and multi-variable regulators developed for individual operating conditions. Proportional/Integral gain schedules were developed and were incorporated into a transition controller with capabilities for mode switching and manipulated variable reassignment. A non-linear component-level transient model of the engine was developed and utilized to provide a preliminary check-out of the controller logic. An inlet and nozzle effects model was developed for subsequent incorporation into the engine model and an aircraft model was developed for preliminary flight transition simulations. A condition monitoring development plan was developed and preliminary design requirements established. The Phase 1 long-range technology plan was refined and restructured toward the development of a real-time high fidelity transient model of a supersonic V/STOL propulsion system and controller for use in a piloted simulation program at NASA-Ames.

Mars entry-to-landing trajectory optimization and closed loop guidance

NASA Technical Reports Server (NTRS)

Ilgen, Marc R.; Manning, Raymund A.; Cruz, Manuel I.

1991-01-01

The guidance strategy of the Mars Rover Sample Return mission is presented in detail. Aeromaneuver versus aerobrake trades are examined, and an aerobrake analysis is presented which takes into account targeting, guidance, flight control, trajectory profile, delivery accuracy. An aeromaneuver analysis is given which includes the entry corridor, maneuver footprint, guidance, preentry phase, constant drag phase, equilibrium guide phase, variable drag phase, influence of trajectory profile on the entry flight loads, parachute deployment conditions and strategies, and landing accuracy. The Mars terminal descent phase is analyzed.

Influence of some formulation variables on the optimization of pH-dependent, colon-targeted, sustained-release mesalamine microspheres.

PubMed

El-Bary, Ahmed Abd; Aboelwafa, Ahmed A; Al Sharabi, Ibrahim M

2012-03-01

The aim of this work was to understand the influence of different formulation variables on the optimization of pH-dependent, colon-targeted, sustained-release mesalamine microspheres prepared by O/O emulsion solvent evaporation method, employing pH-dependent Eudragit S and hydrophobic pH-independent ethylcellulose polymers. Formulation variables studied included concentration of Eudragit S in the internal phase and the ratios between; internal to external phase, drug to Eudragit S and Eudragit S to ethylcellulose to mesalamine. Prepared microspheres were evaluated by carrying out in vitro release studies and determination of particle size, production yield, and encapsulation efficiency. In addition, morphology of microspheres was examined using optical and scanning electron microscopy. Emulsion solvent evaporation method was found to be sensitive to the studied formulation variables. Particle size and encapsulation efficiency increased by increasing Eudragit S concentration in the internal phase, ratio of internal to external phase, and ratio of Eudragit S to the drug. Employing Eudragit S alone in preparation of the microspheres is only successful in forming acid-resistant microspheres with pulsatile release pattern at high pH. Eudragit S and ethylcellulose blend microspheres were able to control release under acidic condition and to extend drug release at high pH. The stability studies carried out at 40°C/75% RH for 6 months proved the stability of the optimized formulation. From the results of this investigation, microencapsulation of mesalamine in microspheres using blend of Eudragit S and ethylcellulose could constitute a promising approach for site-specific and controlled delivery of drug in colon.

Microgravity alters respiratory sinus arrhythmia and short-term heart rate variability in humans

NASA Technical Reports Server (NTRS)

Migeotte, P-F; Prisk, G. Kim; Paiva, M.; West, J. B. (Principal Investigator)

2003-01-01

We studied heart rate (HR), heart rate variability (HRV), and respiratory sinus arrhythmia (RSA) in four male subjects before, during, and after 16 days of spaceflight. The electrocardiogram and respiration were recorded during two periods of 4 min controlled breathing at 7.5 and 15 breaths/min in standing and supine postures on the ground and in microgravity. Low (LF)- and high (HF)-frequency components of the short-term HRV (< or =3 min) were computed through Fourier spectral analysis of the R-R intervals. Early in microgravity, HR was decreased compared with both standing and supine positions and had returned to the supine value by the end of the flight. In microgravity, overall variability, the LF-to-HF ratio, and RSA amplitude and phase were similar to preflight supine values. Immediately postflight, HR increased by approximately 15% and remained elevated 15 days after landing. LF/HF was increased, suggesting an increased sympathetic control of HR standing. The overall variability and RSA amplitude in supine decreased postflight, suggesting that vagal tone decreased, which coupled with the decrease in RSA phase shift suggests that this was the result of an adaptation of autonomic control of HR to microgravity. In addition, these alterations persisted for at least 15 days after return to normal gravity (1G).

Heart rate variability is enhanced in controls but not maladaptive perfectionists during brief mindfulness meditation following stress-induction: A stratified-randomized trial.

PubMed

Azam, Muhammad Abid; Katz, Joel; Fashler, Samantha R; Changoor, Tina; Azargive, Saam; Ritvo, Paul

2015-10-01

Heart rate variability (HRV) is a vagal nerve-mediated biomarker of cardiac function used to investigate chronic illness, psychopathology, stress and, more recently, attention-regulation processes such as meditation. This study investigated HRV in relation to maladaptive perfectionism, a stress-related personality factor, and mindfulness meditation, a stress coping practice expected to elevate HRV, and thereby promote relaxation. Maladaptive perfectionists (n=21) and Controls (n=39) were exposed to a lab-based assessment in which HRV was measured during (1) a 5-minute baseline resting phase, (2) a 5-minute cognitive stress-induction phase, and (3) a post-stress phase. In the post-stress phase, participants were randomly assigned to a 10-minute audio-instructed mindfulness meditation condition or a 10-minute rest condition with audio-description of mindfulness meditation. Analyses revealed a significant elevation in HRV during meditation for Controls but not for Perfectionists. These results suggest that mindfulness meditation promotes relaxation following cognitive stress and that the perfectionist personality hinders relaxation possibly because of decreased cardiac vagal tone. The results are discussed in the context of developing psychophysiological models to advance therapeutic interventions for distressed populations. Copyright © 2015 Elsevier B.V. All rights reserved.

Optimal control of the gear shifting process for shift smoothness in dual-clutch transmissions

NASA Astrophysics Data System (ADS)

Li, Guoqiang; Görges, Daniel

2018-03-01

The control of the transmission system in vehicles is significant for the driving comfort. In order to design a controller for smooth shifting and comfortable driving, a dynamic model of a dual-clutch transmission is presented in this paper. A finite-time linear quadratic regulator is proposed for the optimal control of the two friction clutches in the torque phase for the upshift process. An integral linear quadratic regulator is introduced to regulate the relative speed difference between the engine and the slipping clutch under the optimization of the input torque during the inertia phase. The control objective focuses on smoothing the upshift process so as to improve the driving comfort. Considering the available sensors in vehicles for feedback control, an observer design is presented to track the immeasurable variables. Simulation results show that the jerk can be reduced both in the torque phase and inertia phase, indicating good shift performance. Furthermore, compared with conventional controllers for the upshift process, the proposed control method can reduce shift jerk and improve shift quality.

Mechanical desorption of a single chain: unusual aspects of phase coexistence at a first-order transition.

PubMed

Skvortsov, Alexander M; Klushin, Leonid I; Polotsky, Alexey A; Binder, Kurt

2012-03-01

The phase transition occurring when a single polymer chain adsorbed at a planar solid surface is mechanically desorbed is analyzed in two statistical ensembles. In the force ensemble, a constant force applied to the nongrafted end of the chain (that is grafted at its other end) is used as a given external control variable. In the z-ensemble, the displacement z of this nongrafted end from the surface is taken as the externally controlled variable. Basic thermodynamic parameters, such as the adsorption energy, exhibit a very different behavior as a function of these control parameters. In the thermodynamic limit of infinite chain length the desorption transition with the force as a control parameter clearly is discontinuous, while in the z-ensemble continuous variations are found. However, one should not be misled by a too-naive application of the Ehrenfest criterion to consider the transition as a continuous transition: rather, one traverses a two-phase coexistence region, where part of the chain is still adsorbed and the other part desorbed and stretched. Similarities with and differences from two-phase coexistence at vapor-liquid transitions are pointed out. The rounding of the singularities due to finite chain length is illustrated by exact calculations for the nonreversal random walk model on the simple cubic lattice. A new concept of local order parameter profiles for the description of the mechanical desorption of adsorbed polymers is suggested. This concept give evidence for both the existence of two-phase coexistence within single polymer chains for this transition and the anomalous character of this two-phase coexistence. Consequences for the proper interpretation of experiments performed in different ensembles are briefly mentioned.

Task-related increases in fatigue predict recovery time after academic stress.

PubMed

Blasche, Gerhard; Zilic, Jelena; Frischenschlager, Oskar

2016-01-01

The aim of this study was to investigate the time course of recovery after an academic exam as a model of high workload and its association with stress-related fatigue. Thirty-six medical students (17 females, 19 males) filled out diaries during an exam phase, starting 2 days prior to the exam, and a control phase 4 weeks after the exam for 14 days, respectively. Fatigue, distress, quality of sleep, and health complaints were assessed. Recovery time was determined for each individual and variable by comparing the 3-day average with the confidence interval of the control phase. Recovery time was predicted by Cox regression analyses. Recovery times of all variables except health complaints were predicted by stress-related fatigue. Half of the individuals had recovered after 6 days, and 80% of the individuals had recovered after 8 days. The time necessary for recovery from work demands is determined by fatigue as a measure of resource depletion.

Evolution and control of the phase competition morphology in a manganite film

NASA Astrophysics Data System (ADS)

Zhou, Haibiao; Wang, Lingfei; Hou, Yubin; Huang, Zhen; Lu, Qingyou; Wu, Wenbin

2015-11-01

The competition among different phases in perovskite manganites is pronounced since their energies are very close under the interplay of charge, spin, orbital and lattice degrees of freedom. To reveal the roles of underlying interactions, many efforts have been devoted towards directly imaging phase transitions at microscopic scales. Here we show images of the charge-ordered insulator (COI) phase transition from a pure ferromagnetic metal with reducing field or increasing temperature in a strained phase-separated manganite film, using a home-built magnetic force microscope. Compared with the COI melting transition, this reverse transition is sharp, cooperative and martensitic-like with astonishingly unique yet diverse morphologies. The COI domains show variable-dimensional growth at different temperatures and their distribution can illustrate the delicate balance of the underlying interactions in manganites. Our findings also display how phase domain engineering is possible and how the phase competition can be tuned in a controllable manner.

Evolution and control of the phase competition morphology in a manganite film.

PubMed

Zhou, Haibiao; Wang, Lingfei; Hou, Yubin; Huang, Zhen; Lu, Qingyou; Wu, Wenbin

2015-11-25

The competition among different phases in perovskite manganites is pronounced since their energies are very close under the interplay of charge, spin, orbital and lattice degrees of freedom. To reveal the roles of underlying interactions, many efforts have been devoted towards directly imaging phase transitions at microscopic scales. Here we show images of the charge-ordered insulator (COI) phase transition from a pure ferromagnetic metal with reducing field or increasing temperature in a strained phase-separated manganite film, using a home-built magnetic force microscope. Compared with the COI melting transition, this reverse transition is sharp, cooperative and martensitic-like with astonishingly unique yet diverse morphologies. The COI domains show variable-dimensional growth at different temperatures and their distribution can illustrate the delicate balance of the underlying interactions in manganites. Our findings also display how phase domain engineering is possible and how the phase competition can be tuned in a controllable manner.

Preconditions for Post-Employment Learning: Preliminary Results from Ongoing Research

ERIC Educational Resources Information Center

Salter, Linda

2011-01-01

This article describes the first phase of a two-phase, mixed-method study. The study, now in progress, explores how and to what extent willingness to engage in learning in mature adulthood is influenced by prior experiences and specific individual personality variables, such as perceived locus of control and degree of self-efficacy. Study…

EVALUATING THE COSTS OF PACKED-TOWER AERATION AND GAC FOR CONTROLLING SELECTED ORGANICS

EPA Science Inventory

This article focuses on a preliminary cost analysis that compares liquid-phase granular activated carbon (GAC) treatment with packed-tower aeration (PTA) treatment, with and without air emissions control. The sensitivity of cost to design and operating variables is also discussed...

Low-Cost Phased Array Antenna for Sounding Rockets, Missiles, and Expendable Launch Vehicles

NASA Technical Reports Server (NTRS)

Mullinix, Daniel; Hall, Kenneth; Smith, Bruce; Corbin, Brian

2012-01-01

A low-cost beamformer phased array antenna has been developed for expendable launch vehicles, rockets, and missiles. It utilizes a conformal array antenna of ring or individual radiators (design varies depending on application) that is designed to be fed by the recently developed hybrid electrical/mechanical (vendor-supplied) phased array beamformer. The combination of these new array antennas and the hybrid beamformer results in a conformal phased array antenna that has significantly higher gain than traditional omni antennas, and costs an order of magnitude or more less than traditional phased array designs. Existing omnidirectional antennas for sounding rockets, missiles, and expendable launch vehicles (ELVs) do not have sufficient gain to support the required communication data rates via the space network. Missiles and smaller ELVs are often stabilized in flight by a fast (i.e. 4 Hz) roll rate. This fast roll rate, combined with vehicle attitude changes, greatly increases the complexity of the high-gain antenna beam-tracking problem. Phased arrays for larger ELVs with roll control are prohibitively expensive. Prior techniques involved a traditional fully electronic phased array solution, combined with highly complex and very fast inertial measurement unit phased array beamformers. The functional operation of this phased array is substantially different from traditional phased arrays in that it uses a hybrid electrical/mechanical beamformer that creates the relative time delays for steering the antenna beam via a small physical movement of variable delay lines. This movement is controlled via an innovative antenna control unit that accesses an internal measurement unit for vehicle attitude information, computes a beam-pointing angle to the target, then points the beam via a stepper motor controller. The stepper motor on the beamformer controls the beamformer variable delay lines that apply the appropriate time delays to the individual array elements to properly steer the beam. The array of phased ring radiators is unique in that it provides improved gain for a small rocket or missile that uses spin stabilization for stability. The antenna pattern created is symmetric about the roll axis (like an omnidirectional wraparound), and is thus capable of providing continuous coverage that is compatible with very fast spinning rockets. For larger ELVs with roll control, a linear array of elements can be used for the 1D scanned beamformer and phased array, or a 2D scanned beamformer can be used with an NxN element array.

Design, analysis, and testing of the Phase 1 CSI Evolutionary Model erectable truss

NASA Technical Reports Server (NTRS)

Gronet, M. J.; Davis, D. A.; Kintis, D. H.; Brillhart, R. D.; Atkins, E. M.

1992-01-01

This report addressed the design, analysis, and testing of the erectable truss structure for the Phase 1 CSI Evolutionary Model (CEM) testbed. The Phase 1 CEM testbed is the second testbed to form part of an ongoing program of focused research at NASA/LaRC in the development of Controls-Structures Integration (CSI) technology. The Phase 1 CEM contains the same overall geometry, weight, and sensor locations as the Phase 0 CEM, but is based in an integrated controller and structure design, whereby both structure and controller design variables are sized simultaneously. The Phase 1 CEM design features seven truss sections composed of struts with tailored mass and stiffness properties. A common erectable joint is used and the strut stiffness is tailored by varying the cross-sectional area. To characterize the structure, static tests were conducted on individual struts and 10-bay truss assemblies. Dynamic tests were conducted on 10-bay truss assemblies as well as the fully-assembled CEM truss. The results indicate that the static and dynamic properties of the structure are predictable, well-characterized, and within the performance requirements established during the Phase 1 CEM integrated controller/structure design analysis.

Water outlet control mechanism for fuel cell system operation in variable gravity environments

NASA Technical Reports Server (NTRS)

Vasquez, Arturo (Inventor); McCurdy, Kerri L. (Inventor); Bradley, Karla F. (Inventor)

2007-01-01

A self-regulated water separator provides centrifugal separation of fuel cell product water from oxidant gas. The system uses the flow energy of the fuel cell's two-phase water and oxidant flow stream and a regulated ejector or other reactant circulation pump providing the two-phase fluid flow. The system further uses a means of controlling the water outlet flow rate away from the water separator that uses both the ejector's or reactant pump's supply pressure and a compressibility sensor to provide overall control of separated water flow either back to the separator or away from the separator.

Variable speed wind turbine generator with zero-sequence filter

DOEpatents

Muljadi, Eduard

1998-01-01

A variable speed wind turbine generator system to convert mechanical power into electrical power or energy and to recover the electrical power or energy in the form of three phase alternating current and return the power or energy to a utility or other load with single phase sinusoidal waveform at sixty (60) hertz and unity power factor includes an excitation controller for generating three phase commanded current, a generator, and a zero sequence filter. Each commanded current signal includes two components: a positive sequence variable frequency current signal to provide the balanced three phase excitation currents required in the stator windings of the generator to generate the rotating magnetic field needed to recover an optimum level of real power from the generator; and a zero frequency sixty (60) hertz current signal to allow the real power generated by the generator to be supplied to the utility. The positive sequence current signals are balanced three phase signals and are prevented from entering the utility by the zero sequence filter. The zero sequence current signals have zero phase displacement from each other and are prevented from entering the generator by the star connected stator windings. The zero sequence filter allows the zero sequence current signals to pass through to deliver power to the utility.

Variable Speed Wind Turbine Generator with Zero-sequence Filter

DOEpatents

Muljadi, Eduard

1998-08-25

A variable speed wind turbine generator system to convert mechanical power into electrical power or energy and to recover the electrical power or energy in the form of three phase alternating current and return the power or energy to a utility or other load with single phase sinusoidal waveform at sixty (60) hertz and unity power factor includes an excitation controller for generating three phase commanded current, a generator, and a zero sequence filter. Each commanded current signal includes two components: a positive sequence variable frequency current signal to provide the balanced three phase excitation currents required in the stator windings of the generator to generate the rotating magnetic field needed to recover an optimum level of real power from the generator; and a zero frequency sixty (60) hertz current signal to allow the real power generated by the generator to be supplied to the utility. The positive sequence current signals are balanced three phase signals and are prevented from entering the utility by the zero sequence filter. The zero sequence current signals have zero phase displacement from each other and are prevented from entering the generator by the star connected stator windings. The zero sequence filter allows the zero sequence current signals to pass through to deliver power to the utility.

Variable speed wind turbine generator with zero-sequence filter

DOEpatents

Muljadi, E.

1998-08-25

A variable speed wind turbine generator system to convert mechanical power into electrical power or energy and to recover the electrical power or energy in the form of three phase alternating current and return the power or energy to a utility or other load with single phase sinusoidal waveform at sixty (60) hertz and unity power factor includes an excitation controller for generating three phase commanded current, a generator, and a zero sequence filter. Each commanded current signal includes two components: a positive sequence variable frequency current signal to provide the balanced three phase excitation currents required in the stator windings of the generator to generate the rotating magnetic field needed to recover an optimum level of real power from the generator; and a zero frequency sixty (60) hertz current signal to allow the real power generated by the generator to be supplied to the utility. The positive sequence current signals are balanced three phase signals and are prevented from entering the utility by the zero sequence filter. The zero sequence current signals have zero phase displacement from each other and are prevented from entering the generator by the star connected stator windings. The zero sequence filter allows the zero sequence current signals to pass through to deliver power to the utility. 14 figs.

Variable Structure PID Control to Prevent Integrator Windup

NASA Technical Reports Server (NTRS)

Hall, C. E.; Hodel, A. S.; Hung, J. Y.

1999-01-01

PID controllers are frequently used to control systems requiring zero steady-state error while maintaining requirements for settling time and robustness (gain/phase margins). PID controllers suffer significant loss of performance due to short-term integrator wind-up when used in systems with actuator saturation. We examine several existing and proposed methods for the prevention of integrator wind-up in both continuous and discrete time implementations.

Release from proactive interference in rat spatial working memory.

PubMed

Roberts, William A; MacDonald, Hayden; Brown, Lyn; Macpherson, Krista

2017-09-01

A three-phase procedure was used to produce proactive interference (PI) in one trial on an eight-arm radial maze. Rats were forced to enter four arms for reward on an initial interference phase, to then enter the four remaining arms on a target phase, and to then choose among all eight arms on a retention test, with only the arms not visited in the target phase containing reward. Control trials involved only the target phase and the retention test. Lower accuracy was found on PI trials than on control trials, but performance on PI trials significantly exceeded chance, showing some retention of target memories. Changes in temporal and reward variables between the interference, target, and retention test phases showed release from PI, but changes in context and pattern of arm entry did not. It is suggested that the release from PI paradigm can be used to understand spatial memory encoding in rats and other species.

Digital Interface Board to Control Phase and Amplitude of Four Channels

NASA Technical Reports Server (NTRS)

Smith, Amy E.; Cook, Brian M.; Khan, Abdur R.; Lux, James P.

2011-01-01

An increasing number of parts are designed with digital control interfaces, including phase shifters and variable attenuators. When designing an antenna array in which each antenna has independent amplitude and phase control, the number of digital control lines that must be set simultaneously can grow very large. Use of a parallel interface would require separate line drivers, more parts, and thus additional failure points. A convenient form of control where single-phase shifters or attenuators could be set or the whole set could be programmed with an update rate of 100 Hz is needed to solve this problem. A digital interface board with a field-programmable gate array (FPGA) can simultaneously control an essentially arbitrary number of digital control lines with a serial command interface requiring only three wires. A small set of short, high-level commands provides a simple programming interface for an external controller. Parity bits are used to validate the control commands. Output timing is controlled within the FPGA to allow for rapid update rates of the phase shifters and attenuators. This technology has been used to set and monitor eight 5-bit control signals via a serial UART (universal asynchronous receiver/transmitter) interface. The digital interface board controls the phase and amplitude of the signals for each element in the array. A host computer running Agilent VEE sends commands via serial UART connection to a Xilinx VirtexII FPGA. The commands are decoded, and either outputs are set or telemetry data is sent back to the host computer describing the status and the current phase and amplitude settings. This technology is an integral part of a closed-loop system in which the angle of arrival of an X-band uplink signal is detected and the appropriate phase shifts are applied to the Ka-band downlink signal to electronically steer the array back in the direction of the uplink signal. It will also be used in the non-beam-steering case to compensate for phase shift variations through power amplifiers. The digital interface board can be used to set four 5-bit phase shifters and four 5-bit attenuators and monitor their current settings. Additionally, it is useful outside of the closed-loop system for beamsteering alone. When the VEE program is started, it prompts the user to initialize variables (to zero) or skip initialization. After that, the program enters into a continuous loop waiting for the telemetry period to elapse or a button to be pushed. A telemetry request is sent when the telemetry period is elapsed (every five seconds). Pushing one of the set or reset buttons will send the appropriate command. When a command is sent, the interface status is returned, and the user will be notified by a pop-up window if any error has occurred. The program runs until the End Program button is depressed.

The effect of newly induced mutations on the fitness of genotypes and populations of yeast (Saccharomyces cerevisiae).

PubMed

Orthen, E; Lange, P; Wöhrmann, K

1984-12-01

This paper analyses the fate of artificially induced mutations and their importance to the fitness of populations of the yeast, Saccharomyces cerevisiae, an increasingly important model organism in population genetics. Diploid strains, treated with UV and EMS, were cultured asexually for approximately 540 generations and under conditions where the asexual growth was interrupted by a sexual phase. Growth rates of 100 randomly sampled diploid clones were estimated at the beginning and at the end of the experiment. After the induction of sporulation the growth rates of 100 randomly sampled spores were measured. UV and EMS treatment decreases the average growth rate of the clones significantly but increases the variability in comparison to the untreated control. After selection over approximately 540 generations, variability in growth rates was reduced to that of the untreated control. No increase in mean population fitness was observed. However, the results show that after selection there still exists a large amount of hidden genetic variability in the populations which is revealed when the clones are cultivated in environments other than those in which selection took place. A sexual phase increased the reduction of the induced variability.

Electrically and spatially controllable PDLC phase gratings for diffraction and modulation of laser beams

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

Hadjichristov, Georgi B., E-mail: georgibh@issp.bas.bg; Marinov, Yordan G.; Petrov, Alexander G.

2016-03-25

We present a study on electrically- and spatially-controllable laser beam diffraction, electrooptic (EO) phase modulation, as well as amplitude-frequency EO modulation by single-layer microscale polymer-dispersed liquid crystal (PDLC) phase gratings (PDLC SLPGs) of interest for device applications. PDLC SLPGs were produced from nematic liquid crystal (LC) E7 in photo-curable NOA65 polymer. The wedge-formed PDLC SLPGs have a continuously variable thickness (2–25 µm). They contain LC droplets of diameters twice as the layer thickness, with a linear-gradient size distribution along the wedge. By applying alternating-current (AC) electric field, the PDLC SLPGs produce efficient: (i) diffraction splitting of transmitted laser beams; (ii)more » spatial redistribution of diffracted light intensity; (iii) optical phase modulation; (iv) amplitude-frequency modulation, all controllable by the driven AC field and the droplet size gradient.« less

Acetabular cartilage defects cause altered hip and knee joint coordination variability during gait.

PubMed

Samaan, Michael A; Teng, Hsiang-Ling; Kumar, Deepak; Lee, Sonia; Link, Thomas M; Majumdar, Sharmila; Souza, Richard B

2015-12-01

Patients with acetabular cartilage defects reported increased pain and disability compared to those without acetabular cartilage defects. The specific effects of acetabular cartilage defects on lower extremity coordination patterns are unclear. The purpose of this study was to determine hip and knee joint coordination variability during gait in those with and without acetabular cartilage defects. A combined approach, consisting of a semi-quantitative MRI-based quantification method and vector coding, was used to assess hip and knee joint coordination variability during gait in those with and without acetabular cartilage lesions. The coordination variability of the hip flexion-extension/knee rotation, hip abduction-adduction/knee rotation, and hip rotation/knee rotation joint couplings were reduced in the acetabular lesion group compared to the control group during loading response of the gait cycle. The lesion group demonstrated increased variability in the hip flexion-extension/knee rotation and hip abduction-adduction/knee rotation joint couplings, compared to the control group, during the terminal stance/pre-swing phase of gait. Reduced variability during loading response in the lesion group may suggest reduced movement strategies and a possible compensation mechanism for lower extremity instability during this phase of the gait cycle. During terminal stance/pre-swing, a larger variability in the lesion group may suggest increased movement strategies and represent a compensation or pain avoidance mechanism caused by the load applied to the hip joint. Copyright © 2015 Elsevier Ltd. All rights reserved.

Writing executable assertions to test flight software

NASA Technical Reports Server (NTRS)

Mahmood, A.; Andrews, D. M.; Mccluskey, E. J.

1984-01-01

An executable assertion is a logical statement about the variables or a block of code. If there is no error during execution, the assertion statement results in a true value. Executable assertions can be used for dynamic testing of software. They can be employed for validation during the design phase, and exception and error detection during the operation phase. The present investigation is concerned with the problem of writing executable assertions, taking into account the use of assertions for testing flight software. They can be employed for validation during the design phase, and for exception handling and error detection during the operation phase The digital flight control system and the flight control software are discussed. The considered system provides autopilot and flight director modes of operation for automatic and manual control of the aircraft during all phases of flight. Attention is given to techniques for writing and using assertions to test flight software, an experimental setup to test flight software, and language features to support efficient use of assertions.

Deep tissue near infrared second derivative spectrophotometry for the assessment of claudication in peripheral arterial disease.

PubMed

Koutsiaris, Aristotle G

2017-01-01

The purpose of this study was the application of a second derivative near infrared spectrophotometric (NIRS) technique to the human calf muscle in order to see if peripheral arterial disease (PAD) patients can be discriminated from control subjects, before, during and after a standard treadmill exercise test. Three groups of human subjects were studied: group A consisted of 10 control subjects and groups B and C were formed by PAD patients classified as Fontaine's stage 2a (5 patients) and 2b (10 patients), respectively. The measurement protocol for all groups was 9.75 minutes of standing up (phase 1), 1 minute of exercise (phase 2) and 1 minute of rest (phase 3). Seven variables were defined at different times from the onset of the measurement protocol. All variables were significantly higher (p < 0.05) in group A in comparison to groups B and C. The level of significance was ten times higher (p < 0.005) at the onset (15 seconds) of the experiment and during phases 2 and 3. However, none of the variables in group B was significantly different from those in group C. It is shown for the first time that a second derivative NIRS technique can discriminate (p = 0.003) healthy subjects from PAD patients, in just 15 seconds of standing, with no exercise requirement. More experiments are required in order to uncover the full potential of the technique in the diagnosis of the PAD.

Neural-fuzzy control system application for monitoring process response and control of anaerobic hybrid reactor in wastewater treatment and biogas production.

PubMed

Waewsak, Chaiwat; Nopharatana, Annop; Chaiprasert, Pawinee

2010-01-01

Based on the developed neural-fuzzy control system for anaerobic hybrid reactor (AHR) in wastewater treatment and biogas production, the neural network with backpropagation algorithm for prediction of the variables pH, alkalinity (Alk) and total volatile acids (TVA) at present day time t was used as input data for the fuzzy logic to calculate the influent feed flow rate that was applied to control and monitor the process response at different operations in the initial, overload influent feeding and the recovery phases. In all three phases, this neural-fuzzy control system showed great potential to control AHR in high stability and performance and quick response. Although in the overloading operation phase II with two fold calculating influent flow rate together with a two fold organic loading rate (OLR), this control system had rapid response and was sensitive to the intended overload. When the influent feeding rate was followed by the calculation of control system in the initial operation phase I and the recovery operation phase III, it was found that the neural-fuzzy control system application was capable of controlling the AHR in a good manner with the pH close to 7, TVA/Alk < 0.4 and COD removal > 80% with biogas and methane yields at 0.45 and 0.30 m3/kg COD removed.

Stabilizing detached Bridgman melt crystal growth: Model-based nonlinear feedback control

NASA Astrophysics Data System (ADS)

Yeckel, Andrew; Daoutidis, Prodromos; Derby, Jeffrey J.

2012-12-01

The dynamics and operability limits of a nonlinear-proportional-integral controller designed to stabilize detached vertical Bridgman crystal growth are studied. The manipulated variable is the pressure difference between upper and lower vapor spaces, and the controlled variable is the gap width at the triple-phase line. The controller consists of a model-based nonlinear component coupled with a standard proportional-integral controller. The nonlinear component is based on a capillary model of shape stability. Perturbations to gap width, pressure difference, wetting angle, and growth angle are studied under both shape stable and shape unstable conditions. The nonlinear-PI controller allows a wider operating range of gain than a standard PI controller used alone, is easier to tune, and eliminates solution multiplicity from closed-loop operation.

Study of a control strategy for grid side converter in doubly- fed wind power system

NASA Astrophysics Data System (ADS)

Zhu, D. J.; Tan, Z. L.; Yuan, F.; Wang, Q. Y.; Ding, M.

2016-08-01

The grid side converter is an important part of the excitation system of doubly-fed asynchronous generator used in wind power system. As a three-phase voltage source PWM converter, it can not only transfer slip power in the form of active power, but also adjust the reactive power of the grid. This paper proposed a control approach for improving its performance. In this control approach, the dc voltage is regulated by a sliding mode variable structure control scheme and current by a variable structure controller based on the input output linearization. The theoretical bases of the sliding mode variable structure control were introduced, and the stability proof was presented. Switching function of the system has been deduced, sliding mode voltage controller model has been established, and the output of the outer voltage loop is the instruction of the inner current loop. Affine nonlinear model of two input two output equations on d-q axis for current has been established its meeting conditions of exact linearization were proved. In order to improve the anti-jamming capability of the system, a variable structure control was added in the current controller, the control law was deduced. The dual-loop control with sliding mode control in outer voltage loop and linearization variable structure control in inner current loop was proposed. Simulation results demonstrate the effectiveness of the proposed control strategy even during the dc reference voltage and system load variation.

Continuous relative phase variability during an exhaustive run in runners with a history of iliotibial band syndrome.

PubMed

Miller, Ross H; Meardon, Stacey A; Derrick, Timothy R; Gillette, Jason C

2008-08-01

Previous research has proposed that a lack of variability in lower extremity coupling during running is associated with pathology. The purpose of the study was to evaluate lower extremity coupling variability in runners with and without a history of iliotibial band syndrome (ITBS) during an exhaustive run. Sixteen runners ran to voluntary exhaustion on a motorized treadmill while a motion capture system recorded reflective marker locations. Eight runners had a history of ITBS. At the start and end of the run, continuous relative phase (CRP) angles and CRP variability between strides were calculated for key lower extremity kinematic couplings. The ITBS runners demonstrated less CRP variability than controls in several couplings between segments that have been associated with knee pain and ITBS symptoms, including tibia rotation-rearfoot motion and rearfoot motion-thigh ad/abduction, but more variability in knee flexion/extension-foot ad/abduction. The ITBS runners also demonstrated low variability at heel strike in coupling between rearfoot motion-tibia rotation. The results suggest that runners prone to ITBS use abnormal segmental coordination patterns, particular in couplings involving thigh ad/abduction and tibia internal/external rotation. Implications for variability in injury etiology are suggested.

Dynamical Galam model

NASA Astrophysics Data System (ADS)

Cheon, Taksu; Galam, Serge

2018-06-01

We introduce a model of temporal evolution of political opinions which amounts to a dynamical extension of Galam model in which the proportions of inflexibles are treated as dynamical variables. We find that the critical value of inflexibles in the original Galam model now turns into a fixed point of the system whose stability controls the phase trajectory of the political opinions. The appearance of two phases is found, in which majority-preserving and regime-changing limit cycles are respectively dominant, and the phase transition between them is observed.

Alteration of rhythmic unimanual tapping and anti-phase bimanual coordination in Alzheimer's disease: A sign of inter-hemispheric disconnection?

PubMed

Martin, Elodie; Blais, Mélody; Albaret, Jean-Michel; Pariente, Jérémie; Tallet, Jessica

2017-10-01

Little attention is paid to motor control in Alzheimer's disease (AD) although it is a relevant sign of central nervous system integrity and functioning. In particular, unimanual and bimanual tapping is a relevant paradigm because it requires intra- and inter-hemispheric transfer (IHT). Previous results indicate that both unimanual and anti-phase tapping requires more IHT than in-phase tapping, especially produced without external stimulation. The aim of the present study was to test the production of unimanual, bimanual in-phase and anti-phase tapping with a synchronization-continuation paradigm with and without visual stimulation in AD patients (N=9) and control participants (N=12). In accordance with our hypothesis, these results suggest that unimanual and anti-phase tapping is more altered in AD than in control participants. Moreover, performance is globally more variable in the AD group. These alterations are discussed in terms of possible IHT modulation, in line with functional and structural findings in AD, revealing changes in the connectivity of brain regions across hemispheres and white matter damage. Copyright © 2017 Elsevier B.V. All rights reserved.

Holonomic Quantum Control with Continuous Variable Systems.

PubMed

Albert, Victor V; Shu, Chi; Krastanov, Stefan; Shen, Chao; Liu, Ren-Bao; Yang, Zhen-Biao; Schoelkopf, Robert J; Mirrahimi, Mazyar; Devoret, Michel H; Jiang, Liang

2016-04-08

Universal computation of a quantum system consisting of superpositions of well-separated coherent states of multiple harmonic oscillators can be achieved by three families of adiabatic holonomic gates. The first gate consists of moving a coherent state around a closed path in phase space, resulting in a relative Berry phase between that state and the other states. The second gate consists of "colliding" two coherent states of the same oscillator, resulting in coherent population transfer between them. The third gate is an effective controlled-phase gate on coherent states of two different oscillators. Such gates should be realizable via reservoir engineering of systems that support tunable nonlinearities, such as trapped ions and circuit QED.

Performance Analysis of Three-Phase Induction Motor with AC Direct and VFD

NASA Astrophysics Data System (ADS)

Kumar, Dinesh

2018-03-01

The electrical machine analysis and performance calculation is a very important aspect of efficient drive system design. The development of power electronics devices and power converters provide smooth speed control of Induction Motors by changing the frequency of input supply. These converters, on one hand are providing a more flexible speed control that also leads to problems of harmonics and their associated ailments like pulsating torque, distorted current and voltage waveforms, increasing losses etc. This paper includes the performance analysis of three phase induction motor with three-phase AC direct and variable frequency drives (VFD). The comparison has been concluded with respect to various parameters. MATLAB-SIMULINKTM is used for the analysis.

Phase Variable O Antigen Biosynthetic Genes Control Expression of the Major Protective Antigen and Bacteriophage Receptor in Vibrio cholerae O1

PubMed Central

Seed, Kimberley D.; Faruque, Shah M.; Mekalanos, John J.; Calderwood, Stephen B.; Qadri, Firdausi; Camilli, Andrew

2012-01-01

The Vibrio cholerae lipopolysaccharide O1 antigen is a major target of bacteriophages and the human immune system and is of critical importance for vaccine design. We used an O1-specific lytic bacteriophage as a tool to probe the capacity of V. cholerae to alter its O1 antigen and identified a novel mechanism by which this organism can modulate O antigen expression and exhibit intra-strain heterogeneity. We identified two phase variable genes required for O1 antigen biosynthesis, manA and wbeL. manA resides outside of the previously recognized O1 antigen biosynthetic locus, and encodes for a phosphomannose isomerase critical for the initial step in O1 antigen biosynthesis. We determined that manA and wbeL phase variants are attenuated for virulence, providing functional evidence to further support the critical role of the O1 antigen for infectivity. We provide the first report of phase variation modulating O1 antigen expression in V. cholerae, and show that the maintenance of these phase variable loci is an important means by which this facultative pathogen can generate the diverse subpopulations of cells needed for infecting the host intestinal tract and for escaping predation by an O1-specific phage. PMID:23028317

Trunk-pelvis coordination during turning: A cross sectional study of young adults with and without a history of low back pain.

PubMed

Smith, Jo Armour; Kulig, Kornelia

2016-07-01

During steady-state locomotion, symptomatic individuals with low back pain demonstrate reduced ability to modulate coordination between the trunk and the pelvis in the axial plane. It is unclear if this is also true during functional locomotor perturbations such as changing direction, or if this change in coordination adaptability persists between symptomatic episodes. The purpose of this study was to compare trunk-pelvis coordination during walking turns in healthy individuals and asymptomatic individuals with a history of low back pain. Participants performed multiple ipsilateral turns. Axial plane inter-segmental coordination and stride-to-stride coordination variability were quantified using the vector coding technique. Frequency of coordination mode and amplitude of coordination variability was compared between groups using Wilcoxon signed-rank tests and paired t-tests respectively. During stance phase of the turn, there was no significant difference in either inter-segmental coordination or coordination variability between groups. Inter-segmental coordination between the trunk and the pelvis was predominantly inphase during this part of the turn. During swing phase, patterns of coordination were more diversified, and individuals with a history of low back pain had significantly greater trunk phase coordination than healthy controls. Coordination variability was the same in both groups. Changes in trunk-pelvis coordination are evident between symptomatic episodes in individuals with a history of low back pain. However, previously demonstrated decreases in coordination variability were not found between symptomatic episodes in individuals with recurrent low back pain and therefore may represent a response to concurrent pain rather than a persistent change in motor control. Copyright © 2016 Elsevier Ltd. All rights reserved.

Stability analysis of BWR nuclear-coupled thermal-hyraulics using a simple model

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

Karve, A.A.; Rizwan-uddin; Dorning, J.J.

1995-09-01

A simple mathematical model is developed to describe the dynamics of the nuclear-coupled thermal-hydraulics in a boiling water reactor (BWR) core. The model, which incorporates the essential features of neutron kinetics, and single-phase and two-phase thermal-hydraulics, leads to simple dynamical system comprised of a set of nonlinear ordinary differential equations (ODEs). The stability boundary is determined and plotted in the inlet-subcooling-number (enthalpy)/external-reactivity operating parameter plane. The eigenvalues of the Jacobian matrix of the dynamical system also are calculated at various steady-states (fixed points); the results are consistent with those of the direct stability analysis and indicate that a Hopf bifurcationmore » occurs as the stability boundary in the operating parameter plane is crossed. Numerical simulations of the time-dependent, nonlinear ODEs are carried out for selected points in the operating parameter plane to obtain the actual damped and growing oscillations in the neutron number density, the channel inlet flow velocity, and the other phase variables. These indicate that the Hopf bifurcation is subcritical, hence, density wave oscillations with growing amplitude could result from a finite perturbation of the system even where the steady-state is stable. The power-flow map, frequently used by reactor operators during start-up and shut-down operation of a BWR, is mapped to the inlet-subcooling-number/neutron-density (operating-parameter/phase-variable) plane, and then related to the stability boundaries for different fixed inlet velocities corresponding to selected points on the flow-control line. The stability boundaries for different fixed inlet subcooling numbers corresponding to those selected points, are plotted in the neutron-density/inlet-velocity phase variable plane and then the points on the flow-control line are related to their respective stability boundaries in this plane.« less

Innovative Strategic Aircraft Design Study (ISADS) Phase 1

DTIC Science & Technology

1978-06-01

will be be applicable to virtually all high-technology aircraft. TECHNICAL APPROACH (U) Required research for the implementation of active controls is...Applicable technologies were assessed In areas of aerodynamics, propulsion, struictures, controls , and stealth, and were found to offer up to SO...15 Nonplanar Wings Variable Camber 17 Laminar Flow 17 Jet Flaps 18 Wing Boundary Layer Control 19 Ground Effect 20 Aeroelastic Tailoring 20 Propulsion

Isochronic carrier-envelope phase-shift compensator.

PubMed

Görbe, Mihaly; Osvay, Karoly; Grebing, Christian; Steinmeyer, Günter

2008-11-15

A concept for orthogonal control of phase and group delay inside a laser cavity by a specially designed compensator assembly is discussed. Similar to the construction of variable polarization retarder, this assembly consists of two thin wedge prisms made from appropriately chosen optical materials. Being shifted as a whole, the assembly allows changing the phase delay with no influence on the cavity round-trip time, whereas relative shifting of the prisms enables adjustment of the latter. This scheme is discussed theoretically and verified experimentally, indicating a factor 30 reduction of the influence on the repetition rate compared to the commonly used silica wedge pair. For a 2pi adjustment of the carrier-envelope phase shift, single-pass timing differences are reduced to the single-femtosecond regime. With negligible distortions of timing and dispersion, the described compensator device greatly simplifies carrier-envelope phase control and experiments in extreme nonlinear optics. Copyright (c) 2008 Optical Society of America.

Intelligent herbicide application system for reduced herbicide vegetation control : phase II-commercialization

DOT National Transportation Integrated Search

2008-12-01

This report describes the development of a commercial prototype intelligent herbicide application system : (IHAS). The improved design incorporates a parallel add-on type fluid handling system to allow existing : variable-rate herbicide injecti...

Anthropomorphic teleoperation: Controlling remote manipulators with the DataGlove

NASA Technical Reports Server (NTRS)

Hale, J. P., II

1992-01-01

A two phase effort was conducted to assess the capabilities and limitations of the DataGlove, a lightweight glove input device that can output signals in real-time based on hand shape, orientation, and movement. The first phase was a period for system integration, checkout, and familiarization in a virtual environment. The second phase was a formal experiment using the DataGlove as input device to control the protoflight manipulator arm (PFMA) - a large telerobotic arm with an 8-ft reach. The first phase was used to explore and understand how the DataGlove functions in a virtual environment, build a virtual PFMA, and consider and select a reasonable teleoperation control methodology. Twelve volunteers (six males and six females) participated in a 2 x 3 (x 2) full-factorial formal experiment using the DataGlove to control the PFMA in a simple retraction, slewing, and insertion task. Two within-subjects variables, time delay (0, 1, and 2 seconds) and PFMA wrist flexibility (rigid/flexible), were manipulated. Gender served as a blocking variable. A main effect of time delay was found for slewing and total task times. Correlations among questionnaire responses, and between questionnaire responses and session mean scores and gender were computed. The experimental data were also compared with data collected in another study that used a six degree-of-freedom handcontroller to control the PFMA in the same task. It was concluded that the DataGlove is a legitimate teleoperations input device that provides a natural, intuitive user interface. From an operational point of view, it compares favorably with other 'standard' telerobotic input devices and should be considered in future trades in teleoperation systems' designs.

Coherent molecular transistor: control through variation of the gate wave function.

PubMed

Ernzerhof, Matthias

2014-03-21

In quantum interference transistors (QUITs), the current through the device is controlled by variation of the gate component of the wave function that interferes with the wave function component joining the source and the sink. Initially, mesoscopic QUITs have been studied and more recently, QUITs at the molecular scale have been proposed and implemented. Typically, in these devices the gate lead is subjected to externally adjustable physical parameters that permit interference control through modifications of the gate wave function. Here, we present an alternative model of a molecular QUIT in which the gate wave function is directly considered as a variable and the transistor operation is discussed in terms of this variable. This implies that we specify the gate current as well as the phase of the gate wave function component and calculate the resulting current through the source-sink channel. Thus, we extend on prior works that focus on the phase of the gate wave function component as a control parameter while having zero or certain discrete values of the current. We address a large class of systems, including finite graphene flakes, and obtain analytic solutions for how the gate wave function controls the transistor.

Global land carbon sink response to temperature and precipitation varies with ENSO phase

DOE PAGES

Fang, Yuanyuan; Michalak, Anna M.; Schwalm, Christopher R.; ...

2017-06-01

Climate variability associated with the El Niño-Southern Oscillation (ENSO) and its consequent impacts on land carbon sink interannual variability have been used as a basis for investigating carbon cycle responses to climate variability more broadly, and to inform the sensitivity of the tropical carbon budget to climate change. Past studies have presented opposing views about whether temperature or precipitation is the primary factor driving the response of the land carbon sink to ENSO. We show that the dominant driver varies with ENSO phase. And whereas tropical temperature explains sink dynamics following El Niño conditions (r TG,P = 0.59, p

Global land carbon sink response to temperature and precipitation varies with ENSO phase

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

Fang, Yuanyuan; Michalak, Anna M.; Schwalm, Christopher R.

Climate variability associated with the El Niño-Southern Oscillation (ENSO) and its consequent impacts on land carbon sink interannual variability have been used as a basis for investigating carbon cycle responses to climate variability more broadly, and to inform the sensitivity of the tropical carbon budget to climate change. Past studies have presented opposing views about whether temperature or precipitation is the primary factor driving the response of the land carbon sink to ENSO. Here, we show that the dominant driver varies with ENSO phase. Whereas tropical temperature explains sink dynamics following El Niño conditions (r TG,P=0.59, p<0.01), the post Lamore » Niña sink is driven largely by tropical precipitation (r PG,T=-0.46, p=0.04). This finding points to an ENSO-phase-dependent interplay between water availability and temperature in controlling the carbon uptake response to climate variations in tropical ecosystems. We further find that none of a suite of ten contemporary terrestrial biosphere models captures these ENSO-phase-dependent responses, highlighting a key uncertainty in modeling climate impacts on the future of the global land carbon sink.« less

Global land carbon sink response to temperature and precipitation varies with ENSO phase

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

Fang, Yuanyuan; Michalak, Anna M.; Schwalm, Christopher R.

Climate variability associated with the El Niño-Southern Oscillation (ENSO) and its consequent impacts on land carbon sink interannual variability have been used as a basis for investigating carbon cycle responses to climate variability more broadly, and to inform the sensitivity of the tropical carbon budget to climate change. Past studies have presented opposing views about whether temperature or precipitation is the primary factor driving the response of the land carbon sink to ENSO. We show that the dominant driver varies with ENSO phase. And whereas tropical temperature explains sink dynamics following El Niño conditions (r TG,P = 0.59, p

Application of optimal control theory to the design of broadband excitation pulses for high-resolution NMR.

PubMed

Skinner, Thomas E; Reiss, Timo O; Luy, Burkhard; Khaneja, Navin; Glaser, Steffen J

2003-07-01

Optimal control theory is considered as a methodology for pulse sequence design in NMR. It provides the flexibility for systematically imposing desirable constraints on spin system evolution and therefore has a wealth of applications. We have chosen an elementary example to illustrate the capabilities of the optimal control formalism: broadband, constant phase excitation which tolerates miscalibration of RF power and variations in RF homogeneity relevant for standard high-resolution probes. The chosen design criteria were transformation of I(z)-->I(x) over resonance offsets of +/- 20 kHz and RF variability of +/-5%, with a pulse length of 2 ms. Simulations of the resulting pulse transform I(z)-->0.995I(x) over the target ranges in resonance offset and RF variability. Acceptably uniform excitation is obtained over a much larger range of RF variability (approximately 45%) than the strict design limits. The pulse performs well in simulations that include homonuclear and heteronuclear J-couplings. Experimental spectra obtained from 100% 13C-labeled lysine show only minimal coupling effects, in excellent agreement with the simulations. By increasing pulse power and reducing pulse length, we demonstrate experimental excitation of 1H over +/-32 kHz, with phase variations in the spectra <8 degrees and peak amplitudes >93% of maximum. Further improvements in broadband excitation by optimized pulses (BEBOP) may be possible by applying more sophisticated implementations of the optimal control formalism.

Carbon dioxide clearance in rabbits during expiratory phase intratracheal pulmonary ventilation.

PubMed

Meyappan, Raju T; Raszynski, Andre; Bohorquez, Jorge; Totapally, Balagangadhar R; Koul, Pulin B; Norozian, Faraz M; Valcourt, Karl; Torbati, Dan

2007-01-01

The purpose of this study was to compare the efficacy of CO2 removal during conventional mechanical ventilation (CMV) with and without expiratory phase intratracheal pulmonary ventilation (expiratory ITPV or Exp-ITPV); and to compare CO2 clearance during Exp-ITPV, in pressure-controlled ventilation (PCV) and in volume-controlled ventilation (VCV) modes. Seven anesthetized rabbits were tracheotomized and intubated using a 4 mm endotracheal tube. Venous and arterial lines were established. The rabbits were paralyzed, mechanically ventilated, and ventilation parameters were adjusted to achieve baseline arterial hypercapnia. Animals were then ventilated during 30-minute trials of CMV and Exp-ITPV, in both PCV and VCV modes. A custom-built, microprocessor-controlled solenoid valve was used to limit ITPV gas flow to the expiratory phase. Proximal and carinal airway pressures and hemodynamic variables were continuously recorded, and arterial blood gases were analyzed at the end of each trial. Exp-ITPV, as compared with CMV, reduced arterial PCO2 by 12% and 21% in PCV and VCV modes, respectively (p < 0.02 and p < 0.001; one-sided paired t test), without significant changes in other cardiorespiratory variables. In conclusion, Exp-ITPV is more effective than CMV in clearing CO2 through a small endotracheal tube. Exp-ITPV is also more effective in VCV mode than PCV mode.

Variables controlling the recovery of ignitable liquid residues from simulated fire debris samples using solid-phase microextraction/gas chromatography

NASA Astrophysics Data System (ADS)

Furton, Kenneth G.; Almirall, Jose R.; Wang, Jing

1999-02-01

In this paper, we present data comparing a variety of different conditions for extracting ignitable liquid residues from simulated fire debris samples in order to optimize the conditions for using Solid Phase Microextraction. A simulated accelerant mixture containing 30 components, including those from light petroleum distillates, medium petroleum distillates and heavy petroleum distillates were used to study the important variables controlling Solid Phase Microextraction (SPME) recoveries. SPME is an inexpensive, rapid and sensitive method for the analysis of volatile residues from the headspace over solid debris samples in a container or directly from aqueous samples followed by GC. The relative effects of controllable variables, including fiber chemistry, adsorption and desorption temperature, extraction time, and desorption time, have been optimized. The addition of water and ethanol to simulated debris samples in a can was shown to increase the sensitivity when using headspace SPME extraction. The relative enhancement of sensitivity has been compared as a function of the hydrocarbon chain length, sample temperature, time, and added ethanol concentrations. The technique has also been optimized to the extraction of accelerants directly from water added to the fire debris samples. The optimum adsorption time for the low molecular weight components was found to be approximately 25 minutes. The high molecular weight components were found at a higher concentration the longer the fiber was exposed to the headspace (up to 1 hr). The higher molecular weight components were also found in higher concentrations in the headspace when water and/or ethanol was added to the debris.

Behavioral Momentum Theory Fails to Account for the Effects of Reinforcement Rate on Resurgence

PubMed Central

Craig, Andrew R.; Shahan, Timothy A.

2017-01-01

The behavioral-momentum model of resurgence predicts reinforcer rates within a resurgence preparation should have three effects on target behavior. First, higher reinforcer rates in baseline (Phase 1) produce more persistent target behavior during extinction plus alternative reinforcement. Second, higher rate alternative reinforcement during Phase 2 generates greater disruption of target responding during extinction. Finally, higher rates of either reinforcement source should produce greater responding when alternative reinforcement is suspended in Phase 3. Recent empirical reports have produced mixed results in terms of these predictions. Thus, the present experiment further examined reinforcer-rate effects on persistence and resurgence. Rats pressed target levers for high-rate or low-rate variable-interval food during Phase 1. In Phase 2, target-lever pressing was extinguished, an alternative nose-poke became available, and nose-poking produced either high-rate variable-interval, low-rate variable-interval, or no (an extinction control) alternative reinforcement. Alternative reinforcement was suspended in Phase 3. For groups that received no alternative reinforcement, target-lever pressing was less persistent following high-rate than low-rate Phase-1 reinforcement. Target behavior was more persistent with low-rate alternative reinforcement than with high-rate alternative reinforcement or extinction alone. Finally, no differences in Phase-3 responding were observed for groups that received either high-rate or low-rate alternative reinforcement, and resurgence occurred only following high-rate alternative reinforcement. These findings are inconsistent with the momentum-based model of resurgence. We conclude this model mischaracterizes the effects of rein-forcer rates on persistence and resurgence of operant behavior. PMID:27193242

Stabilizing detached Bridgman melt crystal growth: Proportional-integral feedback control

NASA Astrophysics Data System (ADS)

Yeckel, Andrew; Daoutidis, Prodromos; Derby, Jeffrey J.

2012-10-01

The dynamics, operability limits, and tuning of a proportional-integral feedback controller to stabilize detached vertical Bridgman crystal growth are analyzed using a capillary model of shape stability. The manipulated variable is the pressure difference between upper and lower vapor spaces, and the controlled variable is the gap width at the triple-phase line. Open and closed loop dynamics of step changes in these state variables are analyzed under both shape stable and shape unstable growth conditions. Effects of step changes in static contact angle and growth angle are also studied. Proportional and proportional-integral control can stabilize unstable growth, but only within tight operability limits imposed by the narrow range of allowed meniscus shapes. These limits are used to establish safe operating ranges of controller gain. Strong nonlinearity of the capillary model restricts the range of perturbations that can be stabilized, and under some circumstances, stabilizes a spurious operating state far from the set point. Stabilizing detachment at low growth angle proves difficult and becomes impossible at zero growth angle.

Reasoning and Action: Implementation of a Decision-Making Program in Sport.

PubMed

Gil-Arias, Alexander; Moreno, M Perla; García-Mas, Alex; Moreno, Alberto; García-González, Luíz; Del Villar, Fernando

2016-09-20

The objective of this study was to apply a decision training programme, based on the use of video-feedback and questioning, in real game time, in order to improve decision-making in volleyball attack actions. A three-phase quasi-experimental design was implemented: Phase A (pre-test), Phase B (Intervention) and Phase C (Retention). The sample was made up of 8 female Under-16 volleyball players, who were divided into two groups: experimental group (n = 4) and control group (n = 4). The independent variable was the decision training program, which was applied for 11 weeks in a training context, more specifically in a 6x6 game situation. The player had to analyze the reasons and causes of the decision taken. The dependent variable was decision-making, which was assessed based on systematic observation, using the "Game Performance Assessment Instrument" (GPAI) (Oslin, Mitchell, & Griffin, 1998). Results showed that, after applying the decision training program, the experimental group showed a significantly higher average percentage of successful decisions than the control group F(1, 6) = 11.26; p = .015; η2 p = .652; 95% CI [056, 360]. These results highlight the need to complement the training process with cognitive tools such as video-feedback and questioning in order to improve athletes' decision-making.

[Postural control disorders in initial phases of whiplash].

PubMed

Pleguezuelos Cobo, Eulogio; García-Alsina, Joan; García Almazán, Concepción; Ortiz Fandiño, Javier; Pérez Mesquida, M Engracia; Guirao Cano, Lluis; Samitier Pastor, Beatriz; Perucho Pont, Cristina; Coll Serra, Estel; Matarrubias, Carlos; Reveron, Genoveva

2009-05-02

Dizziness of variable intensity is a frequent complaint in patients who suffered whiplash and largely documented balance disturbances. The objective of the study was to identify balance disorders in early stage of whiplash after road traffic accidents. Ninety nine women were included in the study. Fifty four women had suffered whiplash within two weeks and 45 were included in a healthy control group. Static posturography on a force platform was carried out in all study participants, by means of the Romberg test in four sequential phases, using the postural sway area (SA) as a dependent variable. Visual Analogic Scale (VAS) and Northwick Park Neck Pain Questionnaire (NPH) were used to evaluate pain and function. Postural sway area increased significantly in each of the consecutive phases in both groups. The differences of the means of the postural sway area were statistically significant in all Romberg phases (p=.009 to P=.000). No correlation was found between SA and VAS or NPH scores. There was a positive correlation between the postural sway area standing on a thick foam cushion placed over the plate with closed eyes and the number of days of transitory incapacity (r=0.414; P=.009). Patients with recent whiplash show a postural control disturbance revealed trough a sequential static posturography analysis. This suggests that the balance disorder is not only a consequence of late whiplash syndrome evolution. Therefore, we should promote early instauration of a specific therapeutic approach if and when the patient refers dizziness and related symptoms.

An Examination of Strategy Implementation During Abstract Nonlinguistic Category Learning in Aphasia.

PubMed

Vallila-Rohter, Sofia; Kiran, Swathi

2015-08-01

Our purpose was to study strategy use during nonlinguistic category learning in aphasia. Twelve control participants without aphasia and 53 participants with aphasia (PWA) completed a computerized feedback-based category learning task consisting of training and testing phases. Accuracy rates of categorization in testing phases were calculated. To evaluate strategy use, strategy analyses were conducted over training and testing phases. Participant data were compared with model data that simulated complex multi-cue, single feature, and random pattern strategies. Learning success and strategy use were evaluated within the context of standardized cognitive-linguistic assessments. Categorization accuracy was higher among control participants than among PWA. The majority of control participants implemented suboptimal or optimal multi-cue and single-feature strategies by testing phases of the experiment. In contrast, a large subgroup of PWA implemented random patterns, or no strategy, during both training and testing phases of the experiment. Person-to-person variability arises not only in category learning ability but also in the strategies implemented to complete category learning tasks. PWA less frequently developed effective strategies during category learning tasks than control participants. Certain PWA may have impairments of strategy development or feedback processing not captured by language and currently probed cognitive abilities.

Lyapunov exponents and phase diagrams reveal multi-factorial control over TRAIL-induced apoptosis

PubMed Central

Aldridge, Bree B; Gaudet, Suzanne; Lauffenburger, Douglas A; Sorger, Peter K

2011-01-01

Receptor-mediated apoptosis proceeds via two pathways: one requiring only a cascade of initiator and effector caspases (type I behavior) and the second requiring an initiator–effector caspase cascade and mitochondrial outer membrane permeabilization (type II behavior). Here, we investigate factors controlling type I versus II phenotypes by performing Lyapunov exponent analysis of an ODE-based model of cell death. The resulting phase diagrams predict that the ratio of XIAP to pro-caspase-3 concentrations plays a key regulatory role: type I behavior predominates when the ratio is low and type II behavior when the ratio is high. Cell-to-cell variability in phenotype is observed when the ratio is close to the type I versus II boundary. By positioning multiple tumor cell lines on the phase diagram we confirm these predictions. We also extend phase space analysis to mutations affecting the rate of caspase-3 ubiquitylation by XIAP, predicting and showing that such mutations abolish all-or-none control over activation of effector caspases. Thus, phase diagrams derived from Lyapunov exponent analysis represent a means to study multi-factorial control over a complex biochemical pathway. PMID:22108795

Performance seeking control program overview

NASA Technical Reports Server (NTRS)

Orme, John S.

1995-01-01

The Performance Seeking Control (PSC) program evolved from a series of integrated propulsion-flight control research programs flown at NASA Dryden Flight Research Center (DFRC) on an F-15. The first of these was the Digital Electronic Engine Control (DEEC) program and provided digital engine controls suitable for integration. The DEEC and digital electronic flight control system of the NASA F-15 were ideally suited for integrated controls research. The Advanced Engine Control System (ADECS) program proved that integrated engine and aircraft control could improve overall system performance. The objective of the PSC program was to advance the technology for a fully integrated propulsion flight control system. Whereas ADECS provided single variable control for an average engine, PSC controlled multiple propulsion system variables while adapting to the measured engine performance. PSC was developed as a model-based, adaptive control algorithm and included four optimization modes: minimum fuel flow at constant thrust, minimum turbine temperature at constant thrust, maximum thrust, and minimum thrust. Subsonic and supersonic flight testing were conducted at NASA Dryden covering the four PSC optimization modes and over the full throttle range. Flight testing of the PSC algorithm, conducted in a series of five flight test phases, has been concluded at NASA Dryden covering all four of the PSC optimization modes. Over a three year period and five flight test phases 72 research flights were conducted. The primary objective of flight testing was to exercise each PSC optimization mode and quantify the resulting performance improvements.

Method and apparatus for stabilizing pulsed microwave amplifiers

DOEpatents

Hopkins, Donald B.

1993-01-01

Phase and amplitude variations at the output of a high power pulsed microwave amplifier arising from instabilities of the driving electron beam are suppressed with a feed-forward system that can stabilize pulses which are too brief for regulation by conventional feedback techniques. Such variations tend to be similar during successive pulses. The variations are detected during each pulse by comparing the amplifier output with the low power input signal to obtain phase and amplitude error signals. This enables storage of phase and amplitude correction signals which are used to make compensating changes in the low power input signal during the following amplifier output pulse which suppress the variations. In the preferred form of the invention, successive increments of the correction signals for each pulse are stored in separate channels of a multi-channel storage. Sequential readout of the increments during the next pulse provides variable control voltages to a voltage controlled phase shifter and voltage controlled amplitude modulator in the amplifier input signal path.

Method and apparatus for stabilizing pulsed microwave amplifiers

DOEpatents

Hopkins, D.B.

1993-01-26

Phase and amplitude variations at the output of a high power pulsed microwave amplifier arising from instabilities of the driving electron beam are suppressed with a feed-forward system that can stabilize pulses which are too brief for regulation by conventional feedback techniques. Such variations tend to be similar during successive pulses. The variations are detected during each pulse by comparing the amplifier output with the low power input signal to obtain phase and amplitude error signals. This enables storage of phase and amplitude correction signals which are used to make compensating changes in the low power input signal during the following amplifier output pulse which suppress the variations. In the preferred form of the invention, successive increments of the correction signals for each pulse are stored in separate channels of a multi-channel storage. Sequential readout of the increments during the next pulse provides variable control voltages to a voltage controlled phase shifter and voltage controlled amplitude modulator in the amplifier input signal path.

Analysis of force profile during a maximum voluntary isometric contraction task.

PubMed

Househam, Elizabeth; McAuley, John; Charles, Thompson; Lightfoot, Timothy; Swash, Michael

2004-03-01

This study analyses maximum voluntary isometric contraction (MVIC) and its measurement by recording the force profile during maximal-effort, 7-s hand-grip contractions. Six healthy subjects each performed three trials repeated at short intervals to study variation from fatigue. These three trials were performed during three separate sessions at daily intervals to look at random variation. A pattern of force development during a trial was identified. An initiation phase, with or without an initiation peak, was followed by a maintenance phase, sometimes with secondary pulses and an underlying decline in force. Of these three MVIC parameters, maximum force during the maintenance phase showed less random variability compared to intertrial fatigue variability than did maximum force during the initiation phase or absolute maximum force. Analysis of MVIC as a task, rather than a single, maximal value reveals deeper levels of motor control in its generation. Thus, force parameters other than the absolute maximum force may be better suited to quantification of muscle performance in health and disease.

Adaptive Control Using Residual Mode Filters Applied to Wind Turbines

NASA Technical Reports Server (NTRS)

Frost, Susan A.; Balas, Mark J.

2011-01-01

Many dynamic systems containing a large number of modes can benefit from adaptive control techniques, which are well suited to applications that have unknown parameters and poorly known operating conditions. In this paper, we focus on a model reference direct adaptive control approach that has been extended to handle adaptive rejection of persistent disturbances. We extend this adaptive control theory to accommodate problematic modal subsystems of a plant that inhibit the adaptive controller by causing the open-loop plant to be non-minimum phase. We will augment the adaptive controller using a Residual Mode Filter (RMF) to compensate for problematic modal subsystems, thereby allowing the system to satisfy the requirements for the adaptive controller to have guaranteed convergence and bounded gains. We apply these theoretical results to design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed wind turbine that has minimum phase zeros.

Cerebellar subjects show impaired adaptation of anticipatory EMG during catching.

PubMed

Lang, C E; Bastian, A J

1999-11-01

We evaluated the role of the cerebellum in adapting anticipatory muscle activity during a multijointed catching task. Individuals with and without cerebellar damage caught a series of balls of different weights dropped from above. In Experiment 1 (light-heavy-light), each subject was required to catch light balls (baseline phase), heavy balls (adaptation phase), and then light balls again (postadaptation phase). Subjects were not told when the balls would be switched, and they were required to keep their hand within a vertical spatial "window" during the catch. During the series of trials, we measured three-dimensional (3-D) position and electromyogram (EMG) from the catching arm. We modeled the adaptation process using an exponential decay function; this model allowed us to dissociate adaptation from performance variability. Results from the position data show that cerebellar subjects did not adapt or adapted very slowly to the changed ball weight when compared with the control subjects. The cerebellar group required an average of 30.9 +/- 8.7 trials (mean +/- SE) to progress approximately two-thirds of the way through the adaptation compared with 1.7 +/- 0.2 trials for the control group. Only control subjects showed a negative aftereffect indicating storage of the adaptation. No difference in performance variability existed between the two groups. EMG data show that control subjects increased their anticipatory muscle activity in the flexor muscles of the arm to control the momentum of the ball at impact. Cerebellar subjects were unable to differentially increase the anticipatory muscle activity across three joints to perform the task successfully. In Experiment 2 (heavy-light-heavy), we tested to see whether the rate of adaptation changed when adapting to a light ball versus a heavy ball. Subjects caught the heavy balls (baseline phase), the light balls (adaptation phase), and then heavy balls again (postadaptation phase). Comparison of rates of adaptation between Experiment 1 and Experiment 2 showed that the rate of adaptation was unchanged whether adapting to a light ball or a heavy ball. Given these findings, we conclude that the cerebellum is important in generating the appropriate anticipatory muscle activity across multiple muscles and modifying it in response to changing demands though trial-and-error practice.

Method for removing solid particulate material from within liquid fuel injector assemblies

DOEpatents

Simandl, R.F.; Brown, J.D.; Andriulli, J.B.; Strain, P.D.

1998-09-08

A method is described for removing residual solid particulate material from the interior of liquid fuel injectors and other fluid flow control mechanisms having or being operatively associated with a flow-regulating fixed or variable orifice. The method comprises the sequential and alternate introduction of columns of a non-compressible liquid phase and columns of a compressed gas phase into the body of a fuel injector whereby the expansion of each column of the gas phase across the orifice accelerates the liquid phase in each trailing column of the liquid phase and thereby generates turbulence in each liquid phase for lifting and entraining the solid particulates for the subsequent removal thereof from the body of the fuel injector. 1 fig.

Method for removing solid particulate material from within liquid fuel injector assemblies

DOEpatents

Simandl, Ronald F.; Brown, John D.; Andriulli, John B.; Strain, Paul D.

1998-01-01

A method for removing residual solid particulate material from the interior of liquid fuel injectors and other fluid flow control mechanisms having or being operatively associated with a flow-regulating fixed or variable orifice. The method comprises the sequential and alternate introduction of columns of a non-compressible liquid phase and columns of a compressed gas phase into the body of a fuel injector whereby the expansion of each column of the gas phase across the orifice accelerates the liquid phase in each trailing column of the liquid phase and thereby generates turbulence in each liquid phase for lifting and entraining the solid particulates for the subsequent removal thereof from the body of the fuel injector.

Two aspects of feedforward postural control: anticipatory postural adjustments and anticipatory synergy adjustments.

PubMed

Klous, Miriam; Mikulic, Pavle; Latash, Mark L

2011-05-01

We used the framework of the uncontrolled manifold hypothesis to explore the relations between anticipatory synergy adjustments (ASAs) and anticipatory postural adjustments (APAs) during feedforward control of vertical posture. ASAs represent a drop in the index of a multimuscle-mode synergy stabilizing the coordinate of the center of pressure in preparation to an action. ASAs reflect early changes of an index of covariation among variables reflecting muscle activation, whereas APAs reflect early changes in muscle activation levels averaged across trials. The assumed purpose of ASAs is to modify stability of performance variables, whereas the purpose of APAs is to change magnitudes of those variables. We hypothesized that ASAs would be seen before APAs and that this finding would be consistent with regard to the muscle-mode composition defined on the basis of different tasks and phases of action. Subjects performed a voluntary body sway task and a quick, bilateral shoulder flexion task under self-paced and reaction time conditions. Surface muscle activity of 12 leg and trunk muscles was analyzed to identify sets of 4 muscle modes for each task and for different phases within the shoulder flexion task. Variance components in the muscle-mode space and indexes of multimuscle-mode synergy stabilizing shift of the center of pressure were computed. ASAs were seen ∼ 100-150 ms prior to the task initiation, before APAs. The results were consistent with respect to different sets of muscle modes defined over the two tasks and different shoulder flexion phases. We conclude that the preparation for a self-triggered postural perturbation is associated with two types of anticipatory adjustments, ASAs and APAs. They reflect different feedforward processes within the hypothetical hierarchical control scheme, resulting in changes in patterns of covariation of elemental variables and in their patterns averaged across trials, respectively. The results show that synergies quantified using dissimilar sets of muscle modes show similar feedforward changes in preparation to action.

Variable speed gas engine-driven air compressor system

NASA Astrophysics Data System (ADS)

Morgan, J. R.; Ruggles, A. E.; Chen, T. N.; Gehret, J.

1992-11-01

Tecogen Inc. and Ingersoll-Rand Co. as a subcontractor have designed a nominal 150-hp gas engine-driven air compressor utilizing the TECODRIVE 8000 engine and the Ingersoll-Rand 178.5-mm twin screw compressor. Phase 1 included the system engineering and design, economic and applications studies, and a draft commercialization plan. Phase 2 included controls development, laboratory prototype construction, and performance testing. The testing conducted verified that the compressor meets all design specifications.

Development of a split-flow system for high precision variable sample introduction in supercritical fluid chromatography.

PubMed

Sakai, Miho; Hayakawa, Yoshihiro; Funada, Yasuhiro; Ando, Takashi; Fukusaki, Eiichiro; Bamba, Takeshi

2017-09-15

In this study, we propose a novel variable sample injection system based on full-loop injection, named the split-flow sample introduction system, for application in supercritical fluid chromatography (SFC). In this system, the mobile phase is split by the differential pressure between two back pressure regulators (BPRs) after full-loop injection suitable for SFC, and this differential pressure determines the introduction rate. Nine compounds with a wide range of characteristics were introduced with high reproducibility and universality, confirming that a robust variable sample injection system was achieved. We also investigated the control factors of our proposed system. Sample introduction was controlled by the ratio between the column-side pressure drops in splitless and split flow, ΔP columnsideinsplitless and ΔP columnsideinsplit , respectively, where ΔP columnsideinsplitless is related to the mobile phase flow rate and composition and the column resistance. When all other conditions are kept constant, increasing the make-up flow induces an additional pressure drop on the column side of the system, which leads to a reduced column-side flow rate, and hence decreased the amount of sample injected, even when the net pressure drop on the column side remains the same. Thus, sample introduction could be highly controlled at low sample introduction rate, regardless of the introduction conditions. This feature is advantageous because, as a control factor, the solvent in the make-up pump is independent of the column-side pressure drop. Copyright © 2017. Published by Elsevier B.V.

Exploring Genitoanal Injury and HIV Risk Among Women: Menstrual Phase, Hormonal Birth Control, and Injury Frequency and Prevalence.

PubMed

Brawner, Bridgette M; Sommers, Marilyn S; Moore, Kendra; Aka-James, Rose; Zink, Therese; Brown, Kathleen M; Fargo, Jamison D

2016-02-01

Genital, anal, and oral injuries sustained from sexual intercourse may explain HIV transmission among women. We determined the variability in genitoanal injury frequency and prevalence in women after consensual sexual intercourse, exploring the role of menstrual phase and hormonal birth control. We used a longitudinal observational design with a convenience sample of 393 women aged 21 years and older. Participants had a baseline interview with gynecological examination, followed by consensual sexual intercourse with a male partner and a second gynecological examination. We analyzed injury prevalence with logistic regression and injury frequency with negative binomial regression among women who were (1) menstrual, not using hormonal birth control, (2) menstrual, using hormonal birth control, or (3) menopausal. We also compared injury among menstrual women in the follicular, ovulatory, and luteal phases. Women using hormonal birth control had 38% more external genitalia injuries [adjusted rate ratio (ARR) = 1.38, P = 0.030] and more than twice the anal injuries (ARR = 2.67, P = 0.005) as the nonhormonal birth control menstruating group. Menopausal women had more than 3 times the anal injuries (ARR = 3.36, P = 0.020) than those in the nonhormonal menstrual group. Among menstrual women, those in the follicular phase had a greater prevalence and frequency of external genitalia injuries than those in other phases. Increased rates of postcoital genitoanal injuries are noted among women using hormonal birth control and/or in the follicular phase of menstruation. Biological factors that influence women's risk for HIV warrant further investigation.

Exploring genitoanal injury and HIV risk among women: Menstrual phase, hormonal birth control, and injury frequency and prevalence

PubMed Central

Brawner, Bridgette M.; Sommers, Marilyn S.; Moore, Kendra; Aka-James, Rose; Zink, Therese; Brown, Kathleen M.; Fargo, Jamison D.

2015-01-01

Background Genital, anal and oral injuries sustained from sexual intercourse may explain HIV transmission among women. We determined the variability in genitoanal injury frequency and prevalence in women following consensual sexual intercourse, exploring the role of menstrual phase and hormonal birth control. Methods We used a longitudinal, observational design with a convenience sample of 393 women aged 21 and older. Participants had a baseline interview with gynecologic examination, followed by consensual sexual intercourse with a male partner and a second gynecologic examination. We analyzed injury prevalence with logistic regression and injury frequency with negative binomial regression among women who were: a) menstrual, not using hormonal birth control, b) menstrual, using hormonal birth control, or c) menopausal. We also compared injury among menstrual women in the follicular, ovulatory and luteal phases. Findings Women using hormonal birth control had 38% more external genitalia injuries (adjusted rate ratio [ARR] = 1.38, p = 0.030) and more than twice the anal injuries (ARR = 2.67, p = 0.005) as the non-hormonal birth control menstruating group. Menopausal women had more than three times the anal injuries (ARR = 3.36, p = 0.020) than those in the non-hormonal menstrual group. Among menstrual women, those in the follicular phase had a greater prevalence and frequency of external genitalia injuries than those in other phases. Interpretation Increased rates of post-coital genitoanal injuries are noted among women using hormonal birth control and/or in the follicular phase of menstruation. Biological factors that influence women's risk for HIV warrant further investigation. PMID:26334741

Quadrupedal galloping control for a wide range of speed via vertical impulse scaling.

PubMed

Park, Hae-Won; Kim, Sangbae

2015-03-25

This paper presents a bio-inspired quadruped controller that allows variable-speed galloping. The controller design is inspired by observations from biological runners. Quadrupedal animals increase the vertical impulse that is generated by ground reaction forces at each stride as running speed increases and the duration of each stance phase reduces, whereas the swing phase stays relatively constant. Inspired by this observation, the presented controller estimates the required vertical impulse at each stride by applying the linear momentum conservation principle in the vertical direction and prescribes the ground reaction forces at each stride. The design process begins with deriving a planar model from the MIT Cheetah 2 robot. A baseline periodic limit cycle is obtained by optimizing ground reaction force profiles and the temporal gait pattern (timing and duration of gait phases). To stabilize the optimized limit cycle, the obtained limit cycle is converted to a state feedback controller by representing the obtained ground reaction force profiles as functions of the state variable, which is monotonically increasing throughout the gait, adding impedance control around the height and pitch trajectories of the obtained limit cycle and introducing a finite state machine and a pattern stabilizer to enforce the optimized gait pattern. The controller that achieves a stable 3 m s(-1) gallop successfully adapts the speed change by scaling the vertical ground reaction force to match the momentum lost by gravity and adding a simple speed controller that controls horizontal speed. Without requiring additional gait optimization processes, the controller achieves galloping at speeds ranging from 3 m s(-1) to 14.9 m s(-1) while respecting the torque limit of the motor used in the MIT Cheetah 2 robot. The robustness of the controller is verified by demonstrating stable running during various disturbances, including 1.49 m step down and 0.18 m step up, as well as random ground height and model parameter variations.

Long term variability of the annual hydrological regime and sensitivity to temperature phase shifts in Saxony/Germany

NASA Astrophysics Data System (ADS)

Renner, M.; Bernhofer, C.

2011-01-01

The timing of the seasons strongly effects ecosystems and human activities. Recently, there is increasing evidence of changes in the timing of the seasons, such as earlier spring seasons detected in phenological records, advanced seasonal timing of surface temperature, earlier snow melt or streamflow timing. For water resources management there is a need to quantitatively describe the variability in the timing of hydrological regimes and to understand how climatic changes control the seasonal water budget of river basins on the regional scale. In this study, changes of the annual cycle of hydrological variables are analysed for 27 river basins in Saxony/Germany. Thereby monthly series of basin runoff ratios, the ratio of runoff and basin precipitation are investigated for changes and variability of their annual periodicity over the period 1930-2009. Approximating the annual cycle by the means of harmonic functions gave acceptable results, while only two parameters, phase and amplitude, are required. It has been found that the annual phase of runoff ratio, representing the timing of the hydrological regime, is subject to considerable year-to-year variability, being concurrent with basins in similar hydro-climatic conditions. Two distinct basin classes have been identified, whereby basin elevation has been found to be the delimiting factor. An increasing importance of snow on the basin water balance with elevation is apparent and mainly governs the temporal variability of the annual timing of hydrological regimes. Further there is evidence of coincident changes in trend direction (change points in 1971 and 1988) in snow melt influenced basins. In these basins the timing of the runoff ratio is significantly correlated with the timing of temperature, and effects on runoff by temperature phase changes are even amplified. Interestingly, temperature effects may explain the low frequent variability of the second change point until today. However, the first change point can not be explained by temperature alone and other causes have to be considered.

An experimental study of pilots' control characteristics for flight of an STOL aircraft in backside of drag curve at approach and landing.

PubMed

Ema, T

1992-01-01

In general, most vehicles can be modelled by a multi-variable system which has interactive variables. It can be clearly shown that there is an interactive response in an aircraft's velocity and altitude obtained by stick control and/or throttle control. In particular, if the flight conditions fall to backside of drag curve in the flight of an STOL aircraft at approach and landing then the ratio of drag variation to velocity change has a negative value (delta D/delta u less than 0) and the system of motion presents a non-minimum phase. Therefore, the interaction between velocity and altitude response becomes so complicated that it affects to pilot's control actions and it may be difficult to control the STOL aircraft at approach and landing. In this paper, experimental results of a pilot's ability to control the STOL aircraft are presented for a multi-variable manual control system using a fixed ground base simulator and the pilot's control ability is discussed for the flight of an STOL aircraft at backside of drag curve at approach and landing.

Variability of fire emissions on interannual to multi-decadal timescales in two Earth System models

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

Ward, D. S.; Shevliakova, E.; Malyshev, S.

Connections between wildfires and modes of variability in climate are sought as a means for predicting fire activity on interannual to multi-decadal timescales. Several fire drivers, such as temperature and local drought index, have been shown to vary on these timescales, and analysis of tree-ring data suggests covariance between fires and climate oscillation indices in some regions. HBut, the shortness of the satellite record of global fire events limits investigations on larger spatial scales. Here we explore the interplay between climate variability and wildfire emissions with the preindustrial long control numerical experiments and historical ensembles of CESM1 and the NOAA/GFDLmore » ESM2Mb. We find that interannual variability in fires is underpredicted in both Earth System models (ESMs) compared to present day fire emission inventories. Modeled fire emissions respond to the El Niño/southern oscillation (ENSO) and Pacific decadal oscillation (PDO) with increases in southeast Asia and boreal North America emissions, and decreases in southern North America and Sahel emissions, during the ENSO warm phase in both ESMs, and the PDO warm phase in CESM1. In addition, CESM1 produces decreases in boreal northern hemisphere fire emissions for the warm phase of the Atlantic Meridional Oscillation. Through analysis of the long control simulations, we show that the 20th century trends in both ESMs are statistically significant, meaning that the signal of anthropogenic activity on fire emissions over this time period is detectable above the annual to decadal timescale noise. However, the trends simulated by the two ESMs are of opposite sign (CESM1 decreasing, ESM2Mb increasing), highlighting the need for improved understanding, proxy observations, and modeling to resolve this discrepancy.« less

Variability of fire emissions on interannual to multi-decadal timescales in two Earth System models

NASA Astrophysics Data System (ADS)

Ward, D. S.; Shevliakova, E.; Malyshev, S.; Lamarque, J.-F.; Wittenberg, A. T.

2016-12-01

Connections between wildfires and modes of variability in climate are sought as a means for predicting fire activity on interannual to multi-decadal timescales. Several fire drivers, such as temperature and local drought index, have been shown to vary on these timescales, and analysis of tree-ring data suggests covariance between fires and climate oscillation indices in some regions. However, the shortness of the satellite record of global fire events limits investigations on larger spatial scales. Here we explore the interplay between climate variability and wildfire emissions with the preindustrial long control numerical experiments and historical ensembles of CESM1 and the NOAA/GFDL ESM2Mb. We find that interannual variability in fires is underpredicted in both Earth System models (ESMs) compared to present day fire emission inventories. Modeled fire emissions respond to the El Niño/southern oscillation (ENSO) and Pacific decadal oscillation (PDO) with increases in southeast Asia and boreal North America emissions, and decreases in southern North America and Sahel emissions, during the ENSO warm phase in both ESMs, and the PDO warm phase in CESM1. Additionally, CESM1 produces decreases in boreal northern hemisphere fire emissions for the warm phase of the Atlantic Meridional Oscillation. Through analysis of the long control simulations, we show that the 20th century trends in both ESMs are statistically significant, meaning that the signal of anthropogenic activity on fire emissions over this time period is detectable above the annual to decadal timescale noise. However, the trends simulated by the two ESMs are of opposite sign (CESM1 decreasing, ESM2Mb increasing), highlighting the need for improved understanding, proxy observations, and modeling to resolve this discrepancy.

Variability of fire emissions on interannual to multi-decadal timescales in two Earth System models

DOE PAGES

Ward, D. S.; Shevliakova, E.; Malyshev, S.; ...

2016-12-02

Connections between wildfires and modes of variability in climate are sought as a means for predicting fire activity on interannual to multi-decadal timescales. Several fire drivers, such as temperature and local drought index, have been shown to vary on these timescales, and analysis of tree-ring data suggests covariance between fires and climate oscillation indices in some regions. HBut, the shortness of the satellite record of global fire events limits investigations on larger spatial scales. Here we explore the interplay between climate variability and wildfire emissions with the preindustrial long control numerical experiments and historical ensembles of CESM1 and the NOAA/GFDLmore » ESM2Mb. We find that interannual variability in fires is underpredicted in both Earth System models (ESMs) compared to present day fire emission inventories. Modeled fire emissions respond to the El Niño/southern oscillation (ENSO) and Pacific decadal oscillation (PDO) with increases in southeast Asia and boreal North America emissions, and decreases in southern North America and Sahel emissions, during the ENSO warm phase in both ESMs, and the PDO warm phase in CESM1. In addition, CESM1 produces decreases in boreal northern hemisphere fire emissions for the warm phase of the Atlantic Meridional Oscillation. Through analysis of the long control simulations, we show that the 20th century trends in both ESMs are statistically significant, meaning that the signal of anthropogenic activity on fire emissions over this time period is detectable above the annual to decadal timescale noise. However, the trends simulated by the two ESMs are of opposite sign (CESM1 decreasing, ESM2Mb increasing), highlighting the need for improved understanding, proxy observations, and modeling to resolve this discrepancy.« less

Grain Size as a Control for Melt Focusing Beneath Mid-Ocean Ridges

NASA Astrophysics Data System (ADS)

Turner, A.; Katz, R. F.; Behn, M. D.

2015-12-01

Grain size is a fundamental control on both the rheology and permeability of the mantle. These properties, in turn, affect the transport of melt beneath mid-ocean ridges. Previous models of grain size beneath ridges have considered only the single-phase problem of dynamic recrystallisation and the resultant pattern of grain-size variation [1,2]. These models have not coupled the spatially variable grain-size field to two-phase (partially molten) mechanics to investigate the implications of spatially variable grain size on melt transport. Here, we present new results from numerical models that investigate the consequences of this coupling. In our two-dimensional, two-phase model the grain-size is coupled to both the permeability and rheology. The rheology is strain-rate and grain-size dependent. For simplicity, however, the grain-size field is not computed dynamically — rather, it is imposed from a single-phase, steady-state model [1] that is based on the "wattmeter" theory [3]. Our calculations predicts that a spatially variable grain size field can promote focusing of melt towards the ridge axis. This focusing is distinct from the commonly discussed, sub-lithospheric decompaction channel [4]. Furthermore, our model predicts that the shape of the partially molten region is sensitive to rheological parameters associated with grain size. The comparison of this shape with observations [5] may help to constrain the rheology of the upper mantle beneath mid-ocean ridges. References: [1] Turner et al., Geochem. Geophys. Geosyst., 16, 925-946, 2015. [2] Behn et al., EPSL, 282, 178-189, 2009. [3] Austin and Evans, Geology, 35:343-346, 2007. [4] Sparks and Parmentier, EPSL, 105, 368-377, 1991. [5] Key et al., Nature, 495, 499-502, 2013.

Variable dimensionality in the uranium fluoride/2-methyl-piperazine system: Synthesis and structures of UFO-5, -6, and -7; Zero-, one-, and two-dimensional materials with unprecedented topologies

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

Francis, R.J.; Halasyamani, P.S.; Bee, J.S.

Recently, low temperature (T < 300 C) hydrothermal reactions of inorganic precursors in the presence of organic cations have proven highly productive for the synthesis of novel solid-state materials. Interest in these materials is driven by the astonishingly diverse range of structures produced, as well as by their many potential materials chemistry applications. This report describes the high yield, phase pure hydrothermal syntheses of three new uranium fluoride phases with unprecedented structure types. Through the systematic control of the synthesis conditions the authors have successfully controlled the architecture and dimensionality of the phase formed and selectively synthesized novel zero-, one-,more » and two-dimensional materials.« less

A Context-Driven Model for the Flat Roofs Construction Process through Sensing Systems, Internet-of-Things and Last Planner System

PubMed Central

Andújar-Montoya, María Dolores

2017-01-01

The main causes of building defects are errors in the design and the construction phases. These causes related to construction are mainly due to the general lack of control of construction work and represent approximately 75% of the anomalies. In particular, one of the main causes of such anomalies, which end in building defects, is the lack of control over the physical variables of the work environment during the execution of tasks. Therefore, the high percentage of defects detected in buildings that have the root cause in the construction phase could be avoidable with a more accurate and efficient control of the process. The present work proposes a novel integration model based on information and communications technologies for the automation of both construction work and its management at the execution phase, specifically focused on the flat roof construction process. Roofs represent the second area where more defects are claimed. The proposed model is based on a Web system, supported by a service oriented architecture, for the integral management of tasks through the Last Planner System methodology, but incorporating the management of task restrictions from the physical environment variables by designing specific sensing systems. Likewise, all workers are integrated into the management process by Internet-of-Things solutions that guide them throughout the execution process in a non-intrusive and transparent way. PMID:28737693

A Context-Driven Model for the Flat Roofs Construction Process through Sensing Systems, Internet-of-Things and Last Planner System.

PubMed

Andújar-Montoya, María Dolores; Marcos-Jorquera, Diego; García-Botella, Francisco Manuel; Gilart-Iglesias, Virgilio

2017-07-22

The main causes of building defects are errors in the design and the construction phases. These causes related to construction are mainly due to the general lack of control of construction work and represent approximately 75% of the anomalies. In particular, one of the main causes of such anomalies, which end in building defects, is the lack of control over the physical variables of the work environment during the execution of tasks. Therefore, the high percentage of defects detected in buildings that have the root cause in the construction phase could be avoidable with a more accurate and efficient control of the process. The present work proposes a novel integration model based on information and communications technologies for the automation of both construction work and its management at the execution phase, specifically focused on the flat roof construction process. Roofs represent the second area where more defects are claimed. The proposed model is based on a Web system, supported by a service oriented architecture, for the integral management of tasks through the Last Planner System methodology, but incorporating the management of task restrictions from the physical environment variables by designing specific sensing systems. Likewise, all workers are integrated into the management process by Internet-of-Things solutions that guide them throughout the execution process in a non-intrusive and transparent way.

Chromosomal radiosensitivity in G{sub 2}-phase lymphocytes as an indicator of cancer predisposition

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

Scott, D.; Spreadborough, A.R.; Jones, L.A.

Sanford et al. have reported that G{sub 2}-phase cells from many heritable cancer-prone conditions exhibit higher yields of X-ray-induced chromosome damage than those found in the majority of healthy controls. We have applied their protocol to lymphocytes of a group of control and cancer-prone individuals to see if we could confirm these observations. For control donors we observed higher aberration yields, different kinetics and more interexperiment variability than found by Sanford et al. These differences could not be attributed to unavoidable minor variations in procedures (e.g. serum batches, glassware washing methods), but the difference in X-ray qualities used in themore » two laboratories may have made a small contribution to the discrepancies. We attribute some of our experimental variability to the fact that, to varying extents in different experiments, centrifugation of cells prior to irradiation can slow down the progression of cells into metaphase and that cells can continue to repair during the harvesting procedure (centrifugation and hypotonic treatment). We have applied the assay to cases of ataxia telangiectasia (AT, homozygotes and heterozygotes), xeroderma pigmentosum (homozygotes and heterozygotes), familiar adenomatous polyposis and the syndromes Li-Fraumeni, basal cell nevus, Down`s and Fanconi`s but have been unable to discriminate between these groups and controls except for AT homozygotes. By including a control sample in parallel with samples from cancer-prone groups we found a significant difference in mean aberration yields between controls and AT homozygotes and heterozygotes, but not for the other groups. Since technical features could explain the discrepancies between our laboratories, we have devised our own G{sub 2}-phase assay which appears to be giving promising results. 35 refs., 24 figs., 6 tabs.« less

Integrated Controls-Structures Design Methodology: Redesign of an Evolutionary Test Structure

NASA Technical Reports Server (NTRS)

Maghami, Peiman G.; Gupta, Sandeep; Elliot, Kenny B.; Joshi, Suresh M.

1997-01-01

An optimization-based integrated controls-structures design methodology for a class of flexible space structures is described, and the phase-0 Controls-Structures-Integration evolutionary model, a laboratory testbed at NASA Langley, is redesigned using this integrated design methodology. The integrated controls-structures design is posed as a nonlinear programming problem to minimize the control effort required to maintain a specified line-of-sight pointing performance, under persistent white noise disturbance. Static and dynamic dissipative control strategies are employed for feedback control, and parameters of these controllers are considered as the control design variables. Sizes of strut elements in various sections of the CEM are used as the structural design variables. Design guides for the struts are developed and employed in the integrated design process, to ensure that the redesigned structure can be effectively fabricated. The superiority of the integrated design methodology over the conventional design approach is demonstrated analytically by observing a significant reduction in the average control power needed to maintain specified pointing performance with the integrated design approach.

Statistical quality control and quality assurance evaluation of structural & paving concrete : phase I final report.

DOT National Transportation Integrated Search

2001-08-01

This report discusses the variability associated with the production, construction, and testing of structural and paving concrete. The study evaluated data from over 900 projects constructed between 1992 and 1999, representing over 25,000 lots. The d...

In-flight acoustic measurements on a light twin-engined turboprop airplane

NASA Technical Reports Server (NTRS)

Wilby, J. F.; Mcdaniel, C. D.; Wilby, E. G.

1985-01-01

Four series of flight tests were conducted to measure sound pressure levels inside and outside the cabin of a twin-engined turboprop airplane. Particular emphasis was placed on harmonics of the propeller blade passage frequency. The cabin was unfurnished for the first three flights, when the main objective was to investigate the repeatability of the data. For the fourth flight, the cabin was treated with fiberglass batts. Typically, the exterior sound pressure levels were found to vary 3 to 5 dB for a given harmonic, but variations as high as 8 dB were observed. The variability of harmonic levels within the cabin was slightly higher but depended on control of the relative phase between the propellers; when phase was not controlled the average variability was about 10 dB. Noise reductions provided by the fuselage structure were in the range of 20 to 40 dB, when an exterior microphone in the plane of rotation of the propeller was used as reference.

Relationships between the risk of cardiovascular disease in type 2 diabetes patients and both visit-to-visit variability and time-to-effect differences in blood pressure.

PubMed

Takao, Toshiko; Kimura, Kumiko; Suka, Machi; Yanagisawa, Hiroyuki; Kikuchi, Masatoshi; Kawazu, Shoji; Matsuyama, Yutaka

2015-07-01

To determine whether visit-to-visit blood pressure (BP) variability can predict cardiovascular disease (CVD) incidence in type 2 diabetes patients independently of mean BP, and to analyze the time-to-effect relationship between BP and CVD risk. We retrospectively enrolled 629 type 2 diabetes patients with no history of CVD who first visited our hospital between 1995 and 1996, made at least one hospital visit per year, were followed-up for at least 1 year, and had undergone four or more BP measurements. The patients were followed until June 2012 at the latest. CVD occurred in 66 patients. Variability in systolic or diastolic BP (SBP and DBP, respectively) was a significant predictor of CVD incidence, independent of mean SBP or DBP. CVD incidence was significantly associated with SBP during the preceding 3-5 years, with the highest risk occurring during the preceding 3 years. Visit-to-visit BP variability independently predicts CVD incidence in type 2 diabetes patients. Increased SBP over the preceding 3-5 years indicated a significant CVD risk. To prevent CVD, BP management should focus on stable and well-timed control. In particular, BP stabilization at an early phase and BP control during late phases are important. Copyright © 2015 Elsevier Inc. All rights reserved.

Advanced Flight Simulator: Utilization in A-10 Conversion and Air-to-Surface Attack Training.

DTIC Science & Technology

1981-01-01

ASPT to the A-I0. Finally. the objectivity of the criteria ( parameters of aircraft control. bomb-drop circular error. and percentage of rounds through a...low angle strafe task. Table 4 presents a listing of these tasks and their related release parameters . 12 __ __ _ __ Tab/e .1. A/S Weapons I)eliven...Scoring. Two dependent variables, specific to the phase of student training, were used. In the conversion training phase. specific parameters for

An Examination of Strategy Implementation During Abstract Nonlinguistic Category Learning in Aphasia

PubMed Central

Kiran, Swathi

2015-01-01

Purpose Our purpose was to study strategy use during nonlinguistic category learning in aphasia. Method Twelve control participants without aphasia and 53 participants with aphasia (PWA) completed a computerized feedback-based category learning task consisting of training and testing phases. Accuracy rates of categorization in testing phases were calculated. To evaluate strategy use, strategy analyses were conducted over training and testing phases. Participant data were compared with model data that simulated complex multi-cue, single feature, and random pattern strategies. Learning success and strategy use were evaluated within the context of standardized cognitive–linguistic assessments. Results Categorization accuracy was higher among control participants than among PWA. The majority of control participants implemented suboptimal or optimal multi-cue and single-feature strategies by testing phases of the experiment. In contrast, a large subgroup of PWA implemented random patterns, or no strategy, during both training and testing phases of the experiment. Conclusions Person-to-person variability arises not only in category learning ability but also in the strategies implemented to complete category learning tasks. PWA less frequently developed effective strategies during category learning tasks than control participants. Certain PWA may have impairments of strategy development or feedback processing not captured by language and currently probed cognitive abilities. PMID:25908438

Soil moisture profile variability in land-vegetation- atmosphere continuum

NASA Astrophysics Data System (ADS)

Wu, Wanru

Soil moisture is of critical importance to the physical processes governing energy and water exchanges at the land-air boundary. With respect to the exchange of water mass, soil moisture controls the response of the land surface to atmospheric forcing and determines the partitioning of precipitation into infiltration and runoff. Meanwhile, the soil acts as a reservoir for the storage of liquid water and slow release of water vapor into the atmosphere. The major motivation of the study is that the soil moisture profile is thought to make a substantial contribution to the climate variability through two-way interactions between the land-surface and the atmosphere in the coupled ocean-atmosphere-land climate system. The characteristics of soil moisture variability with soil depth may be important in affecting the atmosphere. The natural variability of soil moisture profile is demonstrated using observations. The 16-year field observational data of soil moisture with 11-layer (top 2.0 meters) measured soil depths over Illinois are analyzed and used to identify and quantify the soil moisture profile variability, where the atmospheric forcing (precipitation) anomaly propagates down through the land-branch of the hydrological cycle with amplitude damping, phase shift, and increasing persistence. Detailed statistical data analyses, which include application of the periodogram method, the wavelet method and the band-pass filter, are made of the variations of soil moisture profile and concurrently measured precipitation for comparison. Cross-spectral analysis is performed to obtain the coherence pattern and phase correlation of two time series for phase shift and amplitude damping calculation. A composite of the drought events during this time period is analyzed and compared with the normal (non-drought) case. A multi-layer land surface model is applied for modeling the soil moisture profile variability characteristics and investigating the underlying mechanisms. Numerical experiments are conducted to examine the impacts of some potential controlling factors, which include atmospheric forcing (periodic and pulse) at the upper boundary, the initial soil moisture profile, the relative root abundance and the soil texture, on the variability of soil moisture profile and the corresponding evapotranspiration. Similar statistical data analyses are performed for the experimental data. Observations from the First International Satellite Land Surface Climatological Project (ISLSCP) Field Experiment (FIFE) are analyzed and used for the testing of model. The integration of the observational and modeling approaches makes it possible to better understand the mechanisms by which the soil moisture profile variability is generated with phase shift, fluctuation amplitude damping and low-pass frequency filtering with soil depth, to improve the strategies of parameterizations in land surface schemes, and furthermore, to assess its contribution to climate variability.

Phase Transition between Black and Blue Phosphorenes: A Quantum Monte Carlo Study

NASA Astrophysics Data System (ADS)

Li, Lesheng; Yao, Yi; Reeves, Kyle; Kanai, Yosuke

Phase transition of the more common black phosphorene to blue phosphorene is of great interest because they are predicted to exhibit unique electronic and optical properties. However, these two phases are predicted to be separated by a rather large energy barrier. In this work, we study the transition pathway between black and blue phosphorenes by using the variable cell nudge elastic band method combined with density functional theory calculation. We show how diffusion quantum Monte Carlo method can be used for determining the energetics of the phase transition and demonstrate the use of two approaches for removing finite-size errors. Finally, we predict how applied stress can be used to control the energetic balance between these two different phases of phosphorene.

Novel Cyclorotor Control System for Operation at Curtate and Prolate Advance Ratios

DTIC Science & Technology

2012-03-06

control mechanisms used until now pitch the blade by attaching control rods from the blade to a rotating eccentric ring. By varying the position of...this eccentric ring the blades are pitched approximately in a sinusoidal manner with variable amplitude and phase; however, this sinusoidal pitching...Florida, June 25-28, 2007. 19Gerhardt, H., "Paddle Wheel Rotorcraft," U.S. Patent 5,265,827, November 30, 1993. 20Bohorquez, F., Rankins, F., Baeder, J

A System-Oriented Approach for the Optimal Control of Process Chains under Stochastic Influences

NASA Astrophysics Data System (ADS)

Senn, Melanie; Schäfer, Julian; Pollak, Jürgen; Link, Norbert

2011-09-01

Process chains in manufacturing consist of multiple connected processes in terms of dynamic systems. The properties of a product passing through such a process chain are influenced by the transformation of each single process. There exist various methods for the control of individual processes, such as classical state controllers from cybernetics or function mapping approaches realized by statistical learning. These controllers ensure that a desired state is obtained at process end despite of variations in the input and disturbances. The interactions between the single processes are thereby neglected, but play an important role in the optimization of the entire process chain. We divide the overall optimization into two phases: (1) the solution of the optimization problem by Dynamic Programming to find the optimal control variable values for each process for any encountered end state of its predecessor and (2) the application of the optimal control variables at runtime for the detected initial process state. The optimization problem is solved by selecting adequate control variables for each process in the chain backwards based on predefined quality requirements for the final product. For the demonstration of the proposed concept, we have chosen a process chain from sheet metal manufacturing with simplified transformation functions.

Microfluidic generation of aqueous two-phase system (ATPS) droplets by controlled pulsating inlet pressures.

PubMed

Moon, Byeong-Ui; Jones, Steven G; Hwang, Dae Kun; Tsai, Scott S H

2015-06-07

We present a technique that generates droplets using ultralow interfacial tension aqueous two-phase systems (ATPS). Our method combines a classical microfluidic flow focusing geometry with precisely controlled pulsating inlet pressure, to form monodisperse ATPS droplets. The dextran (DEX) disperse phase enters through the central inlet with variable on-off pressure cycles controlled by a pneumatic solenoid valve. The continuous phase polyethylene glycol (PEG) solution enters the flow focusing junction through the cross channels at a fixed flow rate. The on-off cycles of the applied pressure, combined with the fixed flow rate cross flow, make it possible for the ATPS jet to break up into droplets. We observe different droplet formation regimes with changes in the applied pressure magnitude and timing, and the continuous phase flow rate. We also develop a scaling model to predict the size of the generated droplets, and the experimental results show a good quantitative agreement with our scaling model. Additionally, we demonstrate the potential for scaling-up of the droplet production rate, with a simultaneous two-droplet generating geometry. We anticipate that this simple and precise approach to making ATPS droplets will find utility in biological applications where the all-biocompatibility of ATPS is desirable.

Environmental Control of Phase Transition and Polyp Survival of a Massive-Outbreaker Jellyfish

PubMed Central

Prieto, Laura; Astorga, Diana; Navarro, Gabriel; Ruiz, Javier

2010-01-01

A number of causes have been proposed to account for the occurrence of gelatinous zooplankton (both jellyfish and ctenophore) blooms. Jellyfish species have a complex life history involving a benthic asexual phase (polyp) and a pelagic sexual phase (medusa). Strong environmental control of jellyfish life cycles is suspected, but not fully understood. This study presents a comprehensive analysis on the physicochemical conditions that control the survival and phase transition of Cotylorhiza tuberculata; a scyphozoan that generates large outbreaks in the Mediterranean Sea. Laboratory experiments indicated that the influence of temperature on strobilation and polyp survival was the critical factor controlling the capacity of this species to proliferate. Early life stages were less sensitive to other factors such as salinity variations or the competitive advantage provided by zooxanthellae in a context of coastal eutrophication. Coherently with laboratory results, the presence/absence of outbreaks of this jellyfish in a particular year seems to be driven by temperature. This is the first time the environmental forcing of the mechanism driving the life cycle of a jellyfish has been disentangled via laboratory experimentation. Projecting this understanding to a field population under climatological variability results in a pattern coherent with in situ records. PMID:21072185

On Chaotic and Hyperchaotic Complex Nonlinear Dynamical Systems

NASA Astrophysics Data System (ADS)

Mahmoud, Gamal M.

Dynamical systems described by real and complex variables are currently one of the most popular areas of scientific research. These systems play an important role in several fields of physics, engineering, and computer sciences, for example, laser systems, control (or chaos suppression), secure communications, and information science. Dynamical basic properties, chaos (hyperchaos) synchronization, chaos control, and generating hyperchaotic behavior of these systems are briefly summarized. The main advantage of introducing complex variables is the reduction of phase space dimensions by a half. They are also used to describe and simulate the physics of detuned laser and thermal convection of liquid flows, where the electric field and the atomic polarization amplitudes are both complex. Clearly, if the variables of the system are complex the equations involve twice as many variables and control parameters, thus making it that much harder for a hostile agent to intercept and decipher the coded message. Chaotic and hyperchaotic complex systems are stated as examples. Finally there are many open problems in the study of chaotic and hyperchaotic complex nonlinear dynamical systems, which need further investigations. Some of these open problems are given.

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

Seiya, K.; Drennan, C.; Pellico, W.

The extraction bucket position in the Fermilab Booster is controlled with a cogging process that involves the comparison of the Booster rf count and the Recycler Ring revolution marker. A one rf bucket jitter in the ex-traction bucket position results from the variability of the process that phase matches the Booster to the Recycler. However, the new slow phase lock process used to lock the frequency and phase of the Booster rf to the Recycler rf has been made digital and programmable and has been modified to correct the extraction notch position. The beam loss at the Recycler injection hasmore » been reduced by 20%. Beam studies and the phase lock system will be discussed in this paper.« less

On the phase form of a deformation quantization with separation of variables

NASA Astrophysics Data System (ADS)

Karabegov, Alexander

2016-06-01

Given a star product with separation of variables on a pseudo-Kähler manifold, we obtain a new formal (1, 1)-form from its classifying form and call it the phase form of the star product. The cohomology class of a star product with separation of variables equals the class of its phase form. We show that the phase forms can be arbitrary and they bijectively parametrize the star products with separation of variables. We also describe the action of a change of the formal parameter on a star product with separation of variables, its formal Berezin transform, classifying form, phase form, and canonical trace density.

Gas network model allows full reservoir coupling

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

Methnani, M.M.

The gas-network flow model (Gasnet) developed for and added to an existing Qatar General Petroleum Corp. (OGPC) in-house reservoir simulator, allows improved modeling of the interaction among the reservoir, wells, and pipeline networks. Gasnet is a three-phase model that is modified to handle gas-condensate systems. The numerical solution is based on a control volume scheme that uses the concept of cells and junctions, whereby pressure and phase densities are defined in cells, while phase flows are defined at junction links. The model features common numerical equations for the reservoir, the well, and the pipeline components and an efficient state-variable solutionmore » method in which all primary variables including phase flows are solved directly. Both steady-state and transient flow events can be simulated with the same tool. Three test cases show how the model runs. One case simulates flow redistribution in a simple two-branch gas network. The second simulates a horizontal gas well in a waterflooded gas reservoir. The third involves an export gas pipeline coupled to a producing reservoir.« less

Integrated digital flight-control system for the space shuttle orbiter

NASA Technical Reports Server (NTRS)

1973-01-01

The integrated digital flight control system is presented which provides rotational and translational control of the space shuttle orbiter in all phases of flight: from launch ascent through orbit to entry and touchdown, and during powered horizontal flights. The program provides a versatile control system structure while maintaining uniform communications with other programs, sensors, and control effectors by using an executive routine/functional subroutine format. The program reads all external variables at a single point, copies them into its dedicated storage, and then calls the required subroutines in the proper sequence. As a result, the flight control program is largely independent of other programs in the GN&C computer complex and is equally insensitive to the characteristics of the processor configuration. The integrated structure of the control system and the DFCS executive routine which embodies that structure are described along with the input and output. The specific estimation and control algorithms used in the various mission phases are given.

Guidance strategies and analysis for low thrust navigation

NASA Technical Reports Server (NTRS)

Jacobson, R. A.

1973-01-01

A low-thrust guidance algorithm suitable for operational use was formulated. A constrained linear feedback control law was obtained using a minimum terminal miss criterion and restricting control corrections to constant changes for specified time periods. Both fixed- and variable-time-of-arrival guidance were considered. The performance of the guidance law was evaluated by applying it to the approach phase of the 1980 rendezvous mission with the comet Encke.

Reliability Studies of Ceramic Capacitors.

DTIC Science & Technology

1984-10-01

Virginia Polytechnic BaTiO 3 Ispecimens with variable composition, density and grain size to be used to make carrier concentration, mobility, thermoelectric ...low fields, observed steady-state electrical behavior will be controlled by the bulk properties of the insulator, the second phase of the conduction...carrier mobility E =applied field Note that bulk properties of the Insulator control the conduction process. From this equation it can be seen that a

Adaptive Time Stepping for Transient Network Flow Simulation in Rocket Propulsion Systems

NASA Technical Reports Server (NTRS)

Majumdar, Alok K.; Ravindran, S. S.

2017-01-01

Fluid and thermal transients found in rocket propulsion systems such as propellant feedline system is a complex process involving fast phases followed by slow phases. Therefore their time accurate computation requires use of short time step initially followed by the use of much larger time step. Yet there are instances that involve fast-slow-fast phases. In this paper, we present a feedback control based adaptive time stepping algorithm, and discuss its use in network flow simulation of fluid and thermal transients. The time step is automatically controlled during the simulation by monitoring changes in certain key variables and by feedback. In order to demonstrate the viability of time adaptivity for engineering problems, we applied it to simulate water hammer and cryogenic chill down in pipelines. Our comparison and validation demonstrate the accuracy and efficiency of this adaptive strategy.

A genetic switch controls the production of flagella and toxins in Clostridium difficile.

PubMed

Anjuwon-Foster, Brandon R; Tamayo, Rita

2017-03-01

In the human intestinal pathogen Clostridium difficile, flagella promote adherence to intestinal epithelial cells. Flagellar gene expression also indirectly impacts production of the glucosylating toxins, which are essential to diarrheal disease development. Thus, factors that regulate the expression of the flgB operon will likely impact toxin production in addition to flagellar motility. Here, we report the identification a "flagellar switch" that controls the phase variable production of flagella and glucosylating toxins. The flagellar switch, located upstream of the flgB operon containing the early stage flagellar genes, is a 154 bp invertible sequence flanked by 21 bp inverted repeats. Bacteria with the sequence in one orientation expressed flagellum and toxin genes, produced flagella, and secreted the toxins ("flg phase ON"). Bacteria with the sequence in the inverse orientation were attenuated for flagellar and toxin gene expression, were aflagellate, and showed decreased toxin secretion ("flg phase OFF"). The orientation of the flagellar switch is reversible during growth in vitro. We provide evidence that gene regulation via the flagellar switch occurs post-transcription initiation and requires a C. difficile-specific regulatory factor to destabilize or degrade the early flagellar gene mRNA when the flagellar switch is in the OFF orientation. Lastly, through mutagenesis and characterization of flagellar phase locked isolates, we determined that the tyrosine recombinase RecV, which catalyzes inversion at the cwpV switch, is also responsible for inversion at the flagellar switch in both directions. Phase variable flagellar motility and toxin production suggests that these important virulence factors have both advantageous and detrimental effects during the course of infection.

The efficacy of the Microsoft KinectTM to assess human bimanual coordination.

PubMed

Liddy, Joshua J; Zelaznik, Howard N; Huber, Jessica E; Rietdyk, Shirley; Claxton, Laura J; Samuel, Arjmand; Haddad, Jeffrey M

2017-06-01

The Microsoft Kinect has been used in studies examining posture and gait. Despite the advantages of portability and low cost, this device has not been used to assess interlimb coordination. Fundamental insights into movement control, variability, health, and functional status can be gained by examining coordination patterns. In this study, we investigated the efficacy of the Microsoft Kinect to capture bimanual coordination relative to a research-grade motion capture system. Twenty-four healthy adults performed coordinated hand movements in two patterns (in-phase and antiphase) at eight movement frequencies (1.00-3.33 Hz). Continuous relative phase (CRP) and discrete relative phase (DRP) were used to quantify the means (mCRP and mDRP) and variability (sdCRP and sdDRP) of coordination patterns. Between-device agreement was assessed using Bland-Altman bias with 95 % limits of agreement, concordance correlation coefficients (absolute agreement), and Pearson correlation coefficients (relative agreement). Modest-to-excellent relative and absolute agreements were found for mCRP in all conditions. However, mDRP showed poor agreement for the in-phase pattern at low frequencies, due to large between-device differences in a subset of participants. By contrast, poor absolute agreement was observed for both sdCRP and sdDRP, while relative agreement ranged from poor to excellent. Overall, the Kinect captures the macroscopic patterns of bimanual coordination better than coordination variability.

A Linear Model of Phase-Dependent Power Correlations in Neuronal Oscillations

PubMed Central

Eriksson, David; Vicente, Raul; Schmidt, Kerstin

2011-01-01

Recently, it has been suggested that effective interactions between two neuronal populations are supported by the phase difference between the oscillations in these two populations, a hypothesis referred to as “communication through coherence” (CTC). Experimental work quantified effective interactions by means of the power correlations between the two populations, where power was calculated on the local field potential and/or multi-unit activity. Here, we present a linear model of interacting oscillators that accounts for the phase dependency of the power correlation between the two populations and that can be used as a reference for detecting non-linearities such as gain control. In the experimental analysis, trials were sorted according to the coupled phase difference of the oscillators while the putative interaction between oscillations was taking place. Taking advantage of the modeling, we further studied the dependency of the power correlation on the uncoupled phase difference, connection strength, and topology. Since the uncoupled phase difference, i.e., the phase relation before the effective interaction, is the causal variable in the CTC hypothesis we also describe how power correlations depend on that variable. For uni-directional connectivity we observe that the width of the uncoupled phase dependency is broader than for the coupled phase. Furthermore, the analytical results show that the characteristics of the phase dependency change when a bidirectional connection is assumed. The width of the phase dependency indicates which oscillation frequencies are optimal for a given connection delay distribution. We propose that a certain width enables a stimulus-contrast dependent extent of effective long-range lateral connections. PMID:21808618

Virtual Constraint Control of a Powered Prosthetic Leg: From Simulation to Experiments with Transfemoral Amputees.

PubMed

Gregg, Robert D; Lenzi, Tommaso; Hargrove, Levi J; Sensinger, Jonathon W

2014-12-01

Recent powered (or robotic) prosthetic legs independently control different joints and time periods of the gait cycle, resulting in control parameters and switching rules that can be difficult to tune by clinicians. This challenge might be addressed by a unifying control model used by recent bipedal robots, in which virtual constraints define joint patterns as functions of a monotonic variable that continuously represents the gait cycle phase. In the first application of virtual constraints to amputee locomotion, this paper derives exact and approximate control laws for a partial feedback linearization to enforce virtual constraints on a prosthetic leg. We then encode a human-inspired invariance property called effective shape into virtual constraints for the stance period. After simulating the robustness of the partial feedback linearization to clinically meaningful conditions, we experimentally implement this control strategy on a powered transfemoral leg. We report the results of three amputee subjects walking overground and at variable cadences on a treadmill, demonstrating the clinical viability of this novel control approach.

Virtual Constraint Control of a Powered Prosthetic Leg: From Simulation to Experiments with Transfemoral Amputees

PubMed Central

Lenzi, Tommaso; Hargrove, Levi J.; Sensinger, Jonathon W.

2014-01-01

Recent powered (or robotic) prosthetic legs independently control different joints and time periods of the gait cycle, resulting in control parameters and switching rules that can be difficult to tune by clinicians. This challenge might be addressed by a unifying control model used by recent bipedal robots, in which virtual constraints define joint patterns as functions of a monotonic variable that continuously represents the gait cycle phase. In the first application of virtual constraints to amputee locomotion, this paper derives exact and approximate control laws for a partial feedback linearization to enforce virtual constraints on a prosthetic leg. We then encode a human-inspired invariance property called effective shape into virtual constraints for the stance period. After simulating the robustness of the partial feedback linearization to clinically meaningful conditions, we experimentally implement this control strategy on a powered transfemoral leg. We report the results of three amputee subjects walking overground and at variable cadences on a treadmill, demonstrating the clinical viability of this novel control approach. PMID:25558185

Observation of optomechanical buckling transitions

PubMed Central

Xu, H.; Kemiktarak, U.; Fan, J.; Ragole, S.; Lawall, J.; Taylor, J. M.

2017-01-01

Correlated phases of matter provide long-term stability for systems as diverse as solids, magnets and potential exotic quantum materials. Mechanical systems, such as buckling transition spring switches, can have engineered, stable configurations whose dependence on a control variable is reminiscent of non-equilibrium phase transitions. In hybrid optomechanical systems, light and matter are strongly coupled, allowing engineering of rapid changes in the force landscape, storing and processing information, and ultimately probing and controlling behaviour at the quantum level. Here we report the observation of first- and second-order buckling transitions between stable mechanical states in an optomechanical system, in which full control of the nature of the transition is obtained by means of the laser power and detuning. The underlying multiwell confining potential we create is highly tunable, with a sub-nanometre distance between potential wells. Our results enable new applications in photonics and information technology, and may enable explorations of quantum phase transitions and macroscopic quantum tunnelling in mechanical systems. PMID:28248293

Titanium dioxide nanoparticles: Impact of increasing ionic strength during synthesis, reflux, and hydrothermal aging

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

Isley, Sara L.; Jordan, David S.; Penn, R. Lee

2009-01-08

This work investigates the role of ionic strength during synthesis, reflux, and hydrothermal aging of sol-gel synthesized titanium dioxide. Research presented here uses X-ray diffraction data and Rietveld refinements to quantify anatase, brookite, and rutile phases as functions of synthetic and aging variables. In addition, the Scherrer equation is used to obtain average crystallite sizes for each phase quantified. Results presented in this work demonstrate that the most control over the sol-gel products can be obtained by modifying the pH during hydrolysis. In addition, while varying the ionic strength during reflux and hydrothermal aging can result in enhanced control overmore » the crystalline phase and crystallite size, the most control can be achieved by varying the ionic strength during synthesis. Finally, sol-gel synthesis at low pH (-0.6) and high-chloride concentration (3 M NaCl) produced a heterogeneous sample composed of nanocrystalline anatase (3.8 nm) and rutile (2.9 nm)« less

A possible four-phase coexistence in a single-component system

NASA Astrophysics Data System (ADS)

Akahane, Kenji; Russo, John; Tanaka, Hajime

2016-08-01

For different phases to coexist in equilibrium at constant temperature T and pressure P, the condition of equal chemical potential μ must be satisfied. This condition dictates that, for a single-component system, the maximum number of phases that can coexist is three. Historically this is known as the Gibbs phase rule, and is one of the oldest and venerable rules of thermodynamics. Here we make use of the fact that, by varying model parameters, the Gibbs phase rule can be generalized so that four phases can coexist even in single-component systems. To systematically search for the quadruple point, we use a monoatomic system interacting with a Stillinger-Weber potential with variable tetrahedrality. Our study indicates that the quadruple point provides flexibility in controlling multiple equilibrium phases and may be realized in systems with tunable interactions, which are nowadays feasible in several soft matter systems such as patchy colloids.

A possible four-phase coexistence in a single-component system

PubMed Central

Akahane, Kenji; Russo, John; Tanaka, Hajime

2016-01-01

For different phases to coexist in equilibrium at constant temperature T and pressure P, the condition of equal chemical potential μ must be satisfied. This condition dictates that, for a single-component system, the maximum number of phases that can coexist is three. Historically this is known as the Gibbs phase rule, and is one of the oldest and venerable rules of thermodynamics. Here we make use of the fact that, by varying model parameters, the Gibbs phase rule can be generalized so that four phases can coexist even in single-component systems. To systematically search for the quadruple point, we use a monoatomic system interacting with a Stillinger–Weber potential with variable tetrahedrality. Our study indicates that the quadruple point provides flexibility in controlling multiple equilibrium phases and may be realized in systems with tunable interactions, which are nowadays feasible in several soft matter systems such as patchy colloids. PMID:27558452

FNAS/summer faculty fellowship research continuation program. Task 6: Integrated model development for liquid fueled rocket propulsion systems. Task 9: Aspects of model-based rocket engine condition monitoring and control

NASA Technical Reports Server (NTRS)

Santi, L. Michael; Helmicki, Arthur J.

1993-01-01

The objective of Phase I of this research effort was to develop an advanced mathematical-empirical model of SSME steady-state performance. Task 6 of Phase I is to develop component specific modification strategy for baseline case influence coefficient matrices. This report describes the background of SSME performance characteristics and provides a description of the control variable basis of three different gains models. The procedure used to establish influence coefficients for each of these three models is also described. Gains model analysis results are compared to Rocketdyne's power balance model (PBM).

Discrete wavelet transform and energy eigen value for rotor bars fault detection in variable speed field-oriented control of induction motor drive.

PubMed

Ameid, Tarek; Menacer, Arezki; Talhaoui, Hicham; Azzoug, Youness

2018-05-03

This paper presents a methodology for the broken rotor bars fault detection is considered when the rotor speed varies continuously and the induction machine is controlled by Field-Oriented Control (FOC). The rotor fault detection is obtained by analyzing a several mechanical and electrical quantities (i.e., rotor speed, stator phase current and output signal of the speed regulator) by the Discrete Wavelet Transform (DWT) in variable speed drives. The severity of the fault is obtained by stored energy calculation for active power signal. Hence, it can be a useful solution as fault indicator. The FOC is implemented in order to preserve a good performance speed control; to compensate the broken rotor bars effect in the mechanical speed and to ensure the operation continuity and to investigate the fault effect in the variable speed. The effectiveness of the technique is evaluated in simulation and in a real-time implementation by using Matlab/Simulink with the real-time interface (RTI) based on dSpace 1104 board. Copyright © 2018. Published by Elsevier Ltd.

Electrowetting Variable Optics for Visible and Infrared Applications

NASA Astrophysics Data System (ADS)

Watson, Alexander Maxwell

Miniaturized variable optical devices are important for the fields of medical technology, optical communication, and consumer imaging devices. Areas ranging from endoscopy and optogenetics to atomic clocks and imaging all benefit from versatile optical systems. These applications all require precise and rapid control of imaging focal depth and lateral scanning. Electrowetting variable optics is one emergent technology that has the capability to provide focus tuning, beam steering, and even phase modulation in a small and robust package which requires no moving parts. Furthermore, electrowetting based devices there are attractive due to their transmissive nature, polarization insensitivity, low insertion loss, low electrical power requirements, and high optical quality. These features mean that electrowetting adaptive optical components are an attractive solution, compared with MEMS and liquid crystal optical components. Electrowetting is a technique that enables control of the shape of a liquid droplet with applied voltage. A conductive droplet on a dielectric surface alters its contact angle due to charges that build up between an underlying electrode and the surface of the droplet. This effect can be used to tune the curvature and tilt of liquids within cavities. The liquid boundary creates a high quality surface to use for lensing or steering applications. This thesis will focus on the development of electrowetting based lenses and prisms and applications in imaging for both visible and infrared wavelengths. Within this dissertation is the first demonstration of electrowetting lenses for phase control, as well as the investigation of non-aqueous electrowetting lens liquids for electrowetting lenses operation in the infrared. Key considerations that affect the performance and reliability are dielectric material and thickness, liquid selection and source of ionic conduction. The optical devices presented herein utilize judicious selection of dielectric material and electrowetting liquids to enable low voltage variable optics and demonstrate applications in microscopy and microendoscopy.

Heart Rate Variability of Athletes Across Concussion Recovery Milestones: A Preliminary Study.

PubMed

Senthinathan, Arrani; Mainwaring, Lynda M; Hutchison, Michael

2017-05-01

To assess heart rate variability (HRV) in athletes with concussion across three phases of recovery. A prospective matched control group design included the collection of HRV and symptoms measured by the Rivermead Post-Concussion Questionnaire. These measures were taken at 3 phases of recovery [(1) symptomatic; (2). asymptomatic; and (3) one-week after return-to-play (RTP)]. The same protocol was completed by noninjured athletes. Interuniversity sports teams at a single institution. 11 athletes, across 7 sports, diagnosed with concussion, and 11 matched-athlete controls volunteered for the study. Physician diagnosed concussion and a sitting to standing protocol for HRV monitoring. The frequency, time, and nonlinear domains of HRV were assessed along with the absolute difference between sitting and standing for each. A 2 x 3 (group x phase) repeated-measures analysis of variance revealed significant interactions for sitting High Frequency (HF) norm, sitting Low Frequency (LF) norm, the difference between sitting and standing HF norm, and difference between sitting and standing LF norm. Acutely, athletes with concussion displayed increased LF norm and decreased HF norm while sitting and a decreased change in their HF and LF norm measures between sitting and standing. A significant group effect for sample entropy when standing was detected, with the concussed group displaying decreased values compared with the matched controls. Athletes with concussion displayed autonomic dysfunction in some measures of HRV that persisted beyond RTP and were related to a previous history of concussion.

Human H-reflexes are smaller in difficult beam walking than in normal treadmill walking.

PubMed

Llewellyn, M; Yang, J F; Prochazka, A

1990-01-01

Hoffman (H) reflexes were elicited from the soleus (SOL) muscle while subjects walked on a treadmill and on a narrow beam (3.5 cm wide, raised 34 cm from the floor). The speed of walking on the treadmill was selected for each subject to match the background activation level of their SOL muscle during beam walking. The normal reciprocal activation pattern of the tibialis anterior and SOL muscles in treadmill walking was replaced by a pattern dominated by co-contraction on the beam. In addition, the step cycle duration was more variable and the time spent in the swing phase was reduced on the beam. The H-reflexes were highly modulated in both tasks, the amplitude being high in the stance phase and low in the swing phase. The H-reflex amplitude was on average 40% lower during beam walking than treadmill walking. The relationship between the H-reflex amplitude and the SOL EMG level was quantified by a regression line relating the two variables. The slope of this line was on average 41% lower in beam walking than treadmill walking. The lower H-reflex gain observed in this study and the high level of fusimotor drive observed in cats performing similar tasks suggest that the two mechanisms which control the excitability of this reflex pathway (i.e. fusimotor action and control of transmission at the muscle spindle to moto-neuron synapse) may be controlled independently.

Advanced supersonic propulsion study, phase 2. [propulsion system performance, design analysis and technology assessment

NASA Technical Reports Server (NTRS)

Howlett, R. A.

1975-01-01

A continuation of the NASA/P and WA study to evaluate various types of propulsion systems for advanced commercial supersonic transports has resulted in the identification of two very promising engine concepts. They are the Variable Stream Control Engine which provides independent temperature and velocity control for two coannular exhaust streams, and a derivative of this engine, a Variable Cycle Engine that employs a rear flow-inverter valve to vary the bypass ratio of the cycle. Both concepts are based on advanced engine technology and have the potential for significant improvements in jet noise, exhaust emissions and economic characteristics relative to current technology supersonic engines. Extensive research and technology programs are required in several critical areas that are unique to these supersonic Variable Cycle Engines to realize these potential improvements. Parametric cycle and integration studies of conventional and Variable Cycle Engines are reviewed, features of the two most promising engine concepts are described, and critical technology requirements and required programs are summarized.

A Computational Model for Aperture Control in Reach-to-Grasp Movement Based on Predictive Variability

PubMed Central

Takemura, Naohiro; Fukui, Takao; Inui, Toshio

2015-01-01

In human reach-to-grasp movement, visual occlusion of a target object leads to a larger peak grip aperture compared to conditions where online vision is available. However, no previous computational and neural network models for reach-to-grasp movement explain the mechanism of this effect. We simulated the effect of online vision on the reach-to-grasp movement by proposing a computational control model based on the hypothesis that the grip aperture is controlled to compensate for both motor variability and sensory uncertainty. In this model, the aperture is formed to achieve a target aperture size that is sufficiently large to accommodate the actual target; it also includes a margin to ensure proper grasping despite sensory and motor variability. To this end, the model considers: (i) the variability of the grip aperture, which is predicted by the Kalman filter, and (ii) the uncertainty of the object size, which is affected by visual noise. Using this model, we simulated experiments in which the effect of the duration of visual occlusion was investigated. The simulation replicated the experimental result wherein the peak grip aperture increased when the target object was occluded, especially in the early phase of the movement. Both predicted motor variability and sensory uncertainty play important roles in the online visuomotor process responsible for grip aperture control. PMID:26696874

The Geometric Phase of Stock Trading.

PubMed

Altafini, Claudio

2016-01-01

Geometric phases describe how in a continuous-time dynamical system the displacement of a variable (called phase variable) can be related to other variables (shape variables) undergoing a cyclic motion, according to an area rule. The aim of this paper is to show that geometric phases can exist also for discrete-time systems, and even when the cycles in shape space have zero area. A context in which this principle can be applied is stock trading. A zero-area cycle in shape space represents the type of trading operations normally carried out by high-frequency traders (entering and exiting a position on a fast time-scale), while the phase variable represents the cash balance of a trader. Under the assumption that trading impacts stock prices, even zero-area cyclic trading operations can induce geometric phases, i.e., profits or losses, without affecting the stock quote.

A new on-chip all-digital three-phase full-bridge dc/ac power inverter with feedforward and frequency control techniques.

PubMed

Chen, Jiann-Jong; Kung, Che-Min

2010-09-01

The communication speed between components is far from satisfactory. To achieve high speed, simple control system configuration, and low cost, a new on-chip all-digital three-phase dc/ac power inverter using feedforward and frequency control techniques is proposed. The controller of the proposed power inverter, called the shift register, consists of six-stage D-latch flip-flops with a goal of achieving low-power consumption and area efficiency. Variable frequency is achieved by controlling the clocks of the shift register. One advantage regarding the data signal (D) and the common clock (CK) is that, regardless of the phase difference between the two, all of the D-latch flip-flops are capable of delaying data by one CK period. To ensure stability, the frequency of CK must be six times higher than that of D. The operation frequency of the proposed power inverter ranges from 10 Hz to 2 MHz, and the maximum output loading current is 0.8 A. The prototype of the proposed circuit has been fabricated with TSMC 0.35 μm 2P4M CMOS processes. The total chip area is 2.333 x 1.698 mm2. The three-phase dc/ac power inverter is applicable in uninterrupted power supplies, cold cathode fluorescent lamps, and motors, because of its ability to convert the dc supply voltage into the three-phase ac power sources.

Dose response relationship in anti-stress gene regulatory networks.

PubMed

Zhang, Qiang; Andersen, Melvin E

2007-03-02

To maintain a stable intracellular environment, cells utilize complex and specialized defense systems against a variety of external perturbations, such as electrophilic stress, heat shock, and hypoxia, etc. Irrespective of the type of stress, many adaptive mechanisms contributing to cellular homeostasis appear to operate through gene regulatory networks that are organized into negative feedback loops. In general, the degree of deviation of the controlled variables, such as electrophiles, misfolded proteins, and O2, is first detected by specialized sensor molecules, then the signal is transduced to specific transcription factors. Transcription factors can regulate the expression of a suite of anti-stress genes, many of which encode enzymes functioning to counteract the perturbed variables. The objective of this study was to explore, using control theory and computational approaches, the theoretical basis that underlies the steady-state dose response relationship between cellular stressors and intracellular biochemical species (controlled variables, transcription factors, and gene products) in these gene regulatory networks. Our work indicated that the shape of dose response curves (linear, superlinear, or sublinear) depends on changes in the specific values of local response coefficients (gains) distributed in the feedback loop. Multimerization of anti-stress enzymes and transcription factors into homodimers, homotrimers, or even higher-order multimers, play a significant role in maintaining robust homeostasis. Moreover, our simulation noted that dose response curves for the controlled variables can transition sequentially through four distinct phases as stressor level increases: initial superlinear with lesser control, superlinear more highly controlled, linear uncontrolled, and sublinear catastrophic. Each phase relies on specific gain-changing events that come into play as stressor level increases. The low-dose region is intrinsically nonlinear, and depending on the level of local gains, presence of gain-changing events, and degree of feedforward gene activation, this region can appear as superlinear, sublinear, or even J-shaped. The general dose response transition proposed here was further examined in a complex anti-electrophilic stress pathway, which involves multiple genes, enzymes, and metabolic reactions. This work would help biologists and especially toxicologists to better assess and predict the cellular impact brought about by biological stressors.

In-flight investigation of the effects of pilot location and control system design on airplane flying qualities for approach and landing

NASA Technical Reports Server (NTRS)

Weingarten, N. C.; Chalk, C. R.

1982-01-01

The handling qualities of large airplanes in the approach and landing flight phase were studied. The primary variables were relative pilot position with respect to center of rotation, command path time delays and phase shifts, augmentation schemes and levels of augmentation. It is indicated that the approach and landing task with large airplanes is a low bandwidth task. Low equivalent short period frequencies and relatively long time delays are tolerated only when the pilot is located at considerable distance forward of the center of rotation. The control problem experienced by the pilots, when seated behind the center of rotation, tended to occur at low altitude when they were using visual cues of rate of sink and altitude. A direct lift controller improved final flight path control of the shuttle like configurations.

Decentralized Feedback Controllers for Robust Stabilization of Periodic Orbits of Hybrid Systems: Application to Bipedal Walking.

PubMed

Hamed, Kaveh Akbari; Gregg, Robert D

2017-07-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially and robustly stabilize periodic orbits for hybrid dynamical systems against possible uncertainties in discrete-time phases. The algorithm assumes a family of parameterized and decentralized nonlinear controllers to coordinate interconnected hybrid subsystems based on a common phasing variable. The exponential and [Formula: see text] robust stabilization problems of periodic orbits are translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities. By investigating the properties of the Poincaré map, some sufficient conditions for the convergence of the iterative algorithm are presented. The power of the algorithm is finally demonstrated through designing a set of robust stabilizing local nonlinear controllers for walking of an underactuated 3D autonomous bipedal robot with 9 degrees of freedom, impact model uncertainties, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg.

Decentralized Feedback Controllers for Robust Stabilization of Periodic Orbits of Hybrid Systems: Application to Bipedal Walking

PubMed Central

Hamed, Kaveh Akbari; Gregg, Robert D.

2016-01-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially and robustly stabilize periodic orbits for hybrid dynamical systems against possible uncertainties in discrete-time phases. The algorithm assumes a family of parameterized and decentralized nonlinear controllers to coordinate interconnected hybrid subsystems based on a common phasing variable. The exponential and H2 robust stabilization problems of periodic orbits are translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities. By investigating the properties of the Poincaré map, some sufficient conditions for the convergence of the iterative algorithm are presented. The power of the algorithm is finally demonstrated through designing a set of robust stabilizing local nonlinear controllers for walking of an underactuated 3D autonomous bipedal robot with 9 degrees of freedom, impact model uncertainties, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg. PMID:28959117

Solar radiation control using nematic curvilinear aligned phase (NCAP) liquid crystal technology

NASA Astrophysics Data System (ADS)

vanKonynenburg, Peter; Marsland, Stephen; McCoy, James

1987-11-01

A new, advanced liquid crystal technology has made economical, large area, electrically-controlled windows a commercial reality. The new technology, Nematic Curvilinear Aligned Phase (NCAP), is based on a polymeric material containing small droplets of nematic liquid crystal which is coated and laminated between transparent electrodes and fabricated into large area field effect devices. NCAP windows feature variable solar transmission and reflection through a voltage-controlled scattering mechanism. Laminated window constructions provide the excellent transmission and visibility of glass in the powered condition. In the unpowered condition, the windows are highly translucent, and provide 1) blocked vision for privacy, security, and obscuration of information, and 2) glare control and solar shading. The stability is excellent during accelerated aging tests. Degradation mechanisms which can limit performance and lifetime are discussed. Maximum long term stability is achieved by product designs that incorporate the appropriate window materials to provide environmental protection.

THE ASSOCIATION BETWEEN MENSTRUAL CYCLE CHARACTERISTICS AND PERCEIVED BODY IMAGE: A CROSS-SECTIONAL SURVEY OF POLISH FEMALE ADOLESCENTS.

PubMed

Kaczmarek, Maria; Trambacz-Oleszak, Sylwia

2016-05-01

The increasing prevalence of negative body perceptions among adolescent girls and the tendency towards wishing to be thinner have become a cultural norm in Western culture. Adolescent girls are particularly vulnerable to developing a negative body image due to physical and sexual changes occurring during puberty. This study aimed to evaluate the association between different measures of body image perceptions and different phases of the menstrual cycle after controlling for weight status and other potential confounders in Polish adolescent girls aged 12-18 years. Three-hundred and thirty participants of a cross-sectional survey conducted in 2009, normally cycling and with no eating disorders, completed a background questionnaire and the Stunkard Figure Rating Scale, and their anthropometric measurements were collected. The dependent outcome variables were measures of body image (actual body image, ideal body image and ideal-self discrepancy) and dichotomous body image perception (satisfied versus dissatisfied) adjusted for other predictor factors: socio-demographic variables, menstrual history and cycle phases, and weight status. One-way ANOVA indicated that weight status, age at menarche and menstrual cycle phase were associated with actual body image and rate of ideal-self discrepancy. Ideal body image was associated with weight status and menstrual cycle phase. General logistic regression models were constructed to evaluate associations of body dissatisfaction and all potential predictor variables. The final selected model of the multiple logistic regression analysis using the backward elimination procedure revealed that adjusted for other factors, negative body image was significantly associated with different phases of the menstrual cycle (p trend=0.033) and increasing body weight status (p trend=0.0007). The likelihood of body dissatisfaction was greatest during the premenstrual phase of the menstrual cycle (OR=2.38; 95% CI 1.06, 5.32) and among girls in obesity class I (OR=8.04; 95% CI 2.37, 27.26). The study confirmed the association between body image dissatisfaction in adolescent girls and different phases of the menstrual cycle after controlling for weight status. The issue of negative body self-image is not only of cognitive, but also of practical value as understanding better the factors contributing to the formation of a negative body image may be instrumental in developing preventive health programmes targeted at young people.

Study of dynamics of X-14B VTOL aircraft

NASA Technical Reports Server (NTRS)

Loscutoff, W. V.; Mitchiner, J. L.; Roesener, R. A.; Seevers, J. A.

1973-01-01

Research was initiated to investigate certain facets of modern control theory and their integration with a digital computer to provide a tractable flight control system for a VTOL aircraft. Since the hover mode is the most demanding phase in the operation of a VTOL aircraft, the research efforts were concentrated in this mode of aircraft operation. Research work on three different aspects of the operation of the X-14B VTOL aircraft is discussed. A general theory for optimal, prespecified, closed-loop control is developed. The ultimate goal was optimal decoupling of the modes of the VTOL aircraft to simplify the pilot's task of handling the aircraft. Modern control theory is used to design deterministic state estimators which provide state variables not measured directly, but which are needed for state variable feedback control. The effect of atmospheric turbulence on the X-14B is investigated. A maximum magnitude gust envelope within which the aircraft could operate stably with the available control power is determined.

Design of state-feedback controllers including sensitivity reduction, with applications to precision pointing

NASA Technical Reports Server (NTRS)

Hadass, Z.

1974-01-01

The design procedure of feedback controllers was described and the considerations for the selection of the design parameters were given. The frequency domain properties of single-input single-output systems using state feedback controllers are analyzed, and desirable phase and gain margin properties are demonstrated. Special consideration is given to the design of controllers for tracking systems, especially those designed to track polynomial commands. As an example, a controller was designed for a tracking telescope with a polynomial tracking requirement and some special features such as actuator saturation and multiple measurements, one of which is sampled. The resulting system has a tracking performance comparing favorably with a much more complicated digital aided tracker. The parameter sensitivity reduction was treated by considering the variable parameters as random variables. A performance index is defined as a weighted sum of the state and control convariances that sum from both the random system disturbances and the parameter uncertainties, and is minimized numerically by adjusting a set of free parameters.

Discontinuity of the annuity curves. III. Two types of vital variability in Drosophila melanogaster.

PubMed

Bychkovskaia, I B; Mylnikov, S V; Mozhaev, G A

2016-01-01

We confirm five-phased construction of Drosophila annuity curves established earlier. Annuity curves were composed of stable five-phase component and variable one. Variable component was due to differences in phase durations. As stable, so variable components were apparent for 60 generations. Stochastic component was described as well. Viability variance which characterize «reaction norm» was apparent for all generation as well. Thus, both types of variability seem to be inherited.

A model of optimal voluntary muscular control.

PubMed

FitzHugh, R

1977-07-19

In the absence of detailed knowledge of how the CNS controls a muscle through its motor fibers, a reasonable hypothesis is that of optimal control. This hypothesis is studied using a simplified mathematical model of a single muscle, based on A.V. Hill's equations, with series elastic element omitted, and with the motor signal represented by a single input variable. Two cost functions were used. The first was total energy expended by the muscle (work plus heat). If the load is a constant force, with no inertia, Hill's optimal velocity of shortening results. If the load includes a mass, analysis by optimal control theory shows that the motor signal to the muscle consists of three phases: (1) maximal stimulation to accelerate the mass to the optimal velocity as quickly as possible, (2) an intermediate level of stimulation to hold the velocity at its optimal value, once reached, and (3) zero stimulation, to permit the mass to slow down, as quickly as possible, to zero velocity at the specified distance shortened. If the latter distance is too small, or the mass too large, the optimal velocity is not reached, and phase (2) is absent. For lengthening, there is no optimal velocity; there are only two phases, zero stimulation followed by maximal stimulation. The second cost function was total time. The optimal control for shortening consists of only phases (1) and (3) above, and is identical to the minimal energy control whenever phase (2) is absent from the latter. Generalization of this model to include viscous loads and a series elastic element are discussed.

A study of the diffusional behavior of a two-phase metal matrix composite exposed to a high temperature environment

NASA Technical Reports Server (NTRS)

Tenney, D. R.

1974-01-01

The progress of diffusion-controlled filament-matrix interaction in a metal matrix composite where the filaments and matrix comprise a two-phase binary alloy system was studied by mathematically modeling compositional changes resulting from prolonged elevated temperature exposure. The analysis treats a finite, diffusion-controlled, two-phase moving-interface problem by means of a variable-grid finite-difference technique. The Ni-W system was selected as an example system. Modeling was carried out for the 1000 to 1200 C temperature range for unidirectional composites containing from 6 to 40 volume percent tungsten filaments in a Ni matrix. The results are displayed to show both the change in filament diameter and matrix composition as a function of exposure time. Compositional profiles produced between first and second nearest neighbor filaments were calculated by superposition of finite-difference solutions of the diffusion equations.

Adaptive guidance for an aero-assisted boost vehicle

NASA Astrophysics Data System (ADS)

Pamadi, Bandu N.; Taylor, Lawrence W., Jr.; Price, Douglas B.

An adaptive guidance system incorporating dynamic pressure constraint is studied for a single stage to low earth orbit (LEO) aero-assist booster with thrust gimbal angle as the control variable. To derive an adaptive guidance law, cubic spline functions are used to represent the ascent profile. The booster flight to LEO is divided into initial and terminal phases. In the initial phase, the ascent profile is continuously updated to maximize the performance of the boost vehicle enroute. A linear feedback control is used in the terminal phase to guide the aero-assisted booster onto the desired LEO. The computer simulation of the vehicle dynamics considers a rotating spherical earth, inverse square (Newtonian) gravity field and an exponential model for the earth's atmospheric density. This adaptive guidance algorithm is capable of handling large deviations in both atmospheric conditions and modeling uncertainties, while ensuring maximum booster performance.

The Geometric Phase of Stock Trading

PubMed Central

2016-01-01

Geometric phases describe how in a continuous-time dynamical system the displacement of a variable (called phase variable) can be related to other variables (shape variables) undergoing a cyclic motion, according to an area rule. The aim of this paper is to show that geometric phases can exist also for discrete-time systems, and even when the cycles in shape space have zero area. A context in which this principle can be applied is stock trading. A zero-area cycle in shape space represents the type of trading operations normally carried out by high-frequency traders (entering and exiting a position on a fast time-scale), while the phase variable represents the cash balance of a trader. Under the assumption that trading impacts stock prices, even zero-area cyclic trading operations can induce geometric phases, i.e., profits or losses, without affecting the stock quote. PMID:27556642

A Kinematic, Flexure-based Mechanism for Precise, Parallel Motion for the Hertz Variable-delay Polarization Modulator (VPM)

NASA Technical Reports Server (NTRS)

Voellmer, G. M.; Chuss, D. T.; Jackson, M.; Krejny, M.; Moseley, S. H.; Novak, G.; Wollack, E. J.

2008-01-01

We describe the design of the linear motion stage for a Variable-delay Polarization Modulator (VPM) and of a grid flattener that has been built and integrated into the Hertz ground-based, submillimeter polarimeter. VPMs allow the modulation of a polarized source by controlling the phase difference between two linear, orthogonal polarizations. The size of the gap between a mirror and a very flat polarizing grid determines the amount of the phase difference. This gap must be parallel to better than 1% of the wavelength. A novel, kinematic, flexure-based mechanism is described that passively maintains the parallelism of the mirror and the grid to 1.5 pm over a 150 mm diameter, with a 400 pm throw. A single piezoceramic actuator is used to modulate the gap, and a capacitive sensor provides position feedback for closed-loop control. A simple device that ensures the planarity of the polarizing grid is also described. Engineering results from the deployment of this device in the Hertz instrument April 2006 at the Submillimeter Telescope Observatory (SMTO) in Arizona are presented.

An observational study of sequential protein-sparing, very low-calorie ketogenic diet (Oloproteic diet) and hypocaloric Mediterranean-like diet for the treatment of obesity.

PubMed

Castaldo, Giuseppe; Monaco, Luigi; Castaldo, Laura; Galdo, Giovanna; Cereda, Emanuele

2016-09-01

The impact of a rehabilitative multi-step dietary program consisting in different diets has been scantily investigated. In an open-label study, 73 obese patients underwent a two-phase weight loss (WL) program: a 3-week protein-sparing, very low-calorie, ketogenic diet (<500 kcal/day; Oloproteic(®) Diet) and a 6-week hypocaloric (25-30 kcal/kg of ideal body weight/day), low glycemic index, Mediterranean-like diet (hypo-MD). Both phases improved visceral adiposity, liver enzymes, GH levels, blood pressure and glucose and lipid metabolism. However, the hypo-MD was responsible for a re-increase in blood lipids and glucose tolerance parameters. Changes in visceral adiposity and glucose control-related variables were more consistent in patients with metabolic syndrome. However, in these patients the hypo-MD did not result in a consistent re-increase in glucose control-related variables. A dietary program consisting in a ketogenic regimen followed by a balanced MD appeared to be feasible and efficacious in reducing cardiovascular risk, particularly in patients with metabolic syndrome.

Hepcidin as a new biomarker for detecting autologous blood transfusion.

PubMed

Leuenberger, Nicolas; Barras, Laura; Nicoli, Raul; Robinson, Neil; Baume, Norbert; Lion, Niels; Barelli, Stefano; Tissot, Jean-Daniel; Saugy, Martial

2016-05-01

Autologous blood transfusion (ABT) is an efficient way to increase sport performance. It is also the most challenging doping method to detect. At present, individual follow-up of haematological variables via the athlete biological passport (ABP) is used to detect it. Quantification of a novel hepatic peptide called hepcidin may be a new alternative to detect ABT. In this prospective clinical trial, healthy subjects received a saline injection for the control phase, after which they donated blood that was stored and then transfused 36 days later. The impact of ABT on hepcidin as well as haematological parameters, iron metabolism, and inflammation markers was investigated. Blood transfusion had a particularly marked effect on hepcidin concentrations compared to the other biomarkers, which included haematological variables. Hepcidin concentrations increased significantly: 12 hr and 1 day after blood reinfusion, these concentrations rose by seven- and fourfold, respectively. No significant change was observed in the control phase. Hepcidin quantification is a cost-effective strategy that could be used in an "ironomics" strategy to improve the detection of ABT. © 2016 Wiley Periodicals, Inc.

Design of a robust control law for the Vega launcher ballistic phase

NASA Astrophysics Data System (ADS)

Valli, Monica; Lavagna, Michèle R.; Panozzo, Thomas

2012-02-01

This work presents the design of a robust control law, and the related control system architecture, for the Vega launcher ballistic phase, taking into account the complete six degrees of freedom dynamics. To gain robustness a non-linear control approach has been preferred: more specifically the Lyapunov's second stability theorem has been exploited, being a very powerful tool to guarantee asymptotic stability of the controlled dynamics. The dynamics of Vega's actuators has also been taken into account. The system performance has been checked and analyzed by numerical simulations run on real mission data for different operational and configuration scenarios, and the effectiveness of the synthesized control highlighted: in particular scenarios including a wide range of composite's inertial configurations performing various typologies of maneuvers have been run. The robustness of the controlled dynamics has been validated by 100 cases Monte Carlo analysis campaign: the containment of the dispersion for the controlled variables - say the composite roll, yaw and pitch angles - confirmed the wide validity and generality of the proposed control law. This paper will show the theoretical approach and discuss the obtained results.

Annual variability of PAH concentrations in the Potomac River watershed

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

Maher, I.L.; Foster, G.D.

1995-12-31

Dynamics of organic contaminant transport in a large river system is influenced by annual variability in organic contaminant concentrations. Surface runoff and groundwater input control the flow of river waters. They are also the two major inputs of contaminants to river waters. The annual variability of contaminant concentrations in rivers may or may not represent similar trends to the flow changes of river waters. The purpose of the research is to define the annual variability in concentrations of polycyclic aromatic hydrocarbons (PAH) in riverine environment. To accomplish this, from March 1992 to March 1995 samples of Potomac River water weremore » collected monthly or bimonthly downstream of the Chesapeake Bay fall line (Chain Bridge) during base flow and main storm flow hydrologic conditions. Concentrations of selected PAHs were measured in the dissolved phase and the particulate phase via GC/MS. The study of the annual variability of PAH concentrations will be performed through comparisons of PAH concentrations seasonally, annually, and through study of PAH concentration river discharge dependency and rainfall dependency. For selected PAHs monthly and annual loadings will be estimated based on their measured concentrations and average daily river discharge. The monthly loadings of selected PAHs will be compared by seasons and annually.« less

Southern Hemisphere extratropical circulation: Recent trends and natural variability

NASA Astrophysics Data System (ADS)

Thomas, Jordan L.; Waugh, Darryn W.; Gnanadesikan, Anand

2015-07-01

Changes in the Southern Annular Mode (SAM), Southern Hemisphere (SH) westerly jet location, and magnitude are linked with changes in ocean circulation along with ocean heat and carbon uptake. Recent trends have been observed in these fields but not much is known about the natural variability. Here we aim to quantify the natural variability of the SH extratropical circulation by using Coupled Model Intercomparison Project Phase 5 (CMIP5) preindustrial control model runs and compare with the observed trends in SAM, jet magnitude, and jet location. We show that trends in SAM are due partly to external forcing but are not outside the natural variability as described by these models. Trends in jet location and magnitude, however, lie outside the unforced natural variability but can be explained by a combination of natural variability and the ensemble mean forced trend. These results indicate that trends in these three diagnostics cannot be used interchangeably.

Mutual information and phase dependencies: measures of reduced nonlinear cardiorespiratory interactions after myocardial infarction.

PubMed

Hoyer, Dirk; Leder, Uwe; Hoyer, Heike; Pompe, Bernd; Sommer, Michael; Zwiener, Ulrich

2002-01-01

The heart rate variability (HRV) is related to several mechanisms of the complex autonomic functioning such as respiratory heart rate modulation and phase dependencies between heart beat cycles and breathing cycles. The underlying processes are basically nonlinear. In order to understand and quantitatively assess those physiological interactions an adequate coupling analysis is necessary. We hypothesized that nonlinear measures of HRV and cardiorespiratory interdependencies are superior to the standard HRV measures in classifying patients after acute myocardial infarction. We introduced mutual information measures which provide access to nonlinear interdependencies as counterpart to the classically linear correlation analysis. The nonlinear statistical autodependencies of HRV were quantified by auto mutual information, the respiratory heart rate modulation by cardiorespiratory cross mutual information, respectively. The phase interdependencies between heart beat cycles and breathing cycles were assessed basing on the histograms of the frequency ratios of the instantaneous heart beat and respiratory cycles. Furthermore, the relative duration of phase synchronized intervals was acquired. We investigated 39 patients after acute myocardial infarction versus 24 controls. The discrimination of these groups was improved by cardiorespiratory cross mutual information measures and phase interdependencies measures in comparison to the linear standard HRV measures. This result was statistically confirmed by means of logistic regression models of particular variable subsets and their receiver operating characteristics.

Brain Oscillations Elicited by the Cold Pressor Test: A Putative Index of Untreated Essential Hypertension.

PubMed

Papageorgiou, Christos; Manios, Efstathios; Tsaltas, Eleftheria; Koroboki, Eleni; Alevizaki, Maria; Angelopoulos, Elias; Dimopoulos, Meletios-Athanasios; Papageorgiou, Charalabos; Zakopoulos, Nikolaos

2017-01-01

Essential hypertension is associated with reduced pain sensitivity of unclear aetiology. This study explores this issue using the Cold Pressor Test (CPT), a reliable pain/stress model, comparing CPT-related EEG activity in first episode hypertensives and controls. 22 untreated hypertensives and 18 matched normotensives underwent 24-hour ambulatory blood pressure monitoring (ABPM). EEG recordings were taken before, during, and after CPT exposure. Significant group differences in CPT-induced EEG oscillations were covaried with the most robust cardiovascular differentiators by means of a Canonical Analysis. Positive correlations were noted between ABPM variables and Delta (1-4 Hz) oscillations during the tolerance phase; in high-alpha (10-12 Hz) oscillations during the stress unit and posttest phase; and in low-alpha (8-10 Hz) oscillations during CPT phases overall. Negative correlations were found between ABPM variables and Beta2 oscillations (16.5-20 Hz) during the posttest phase and Gamma (28.5-45 Hz) oscillations during the CPT phases overall. These relationships were localised at several sites across the cerebral hemispheres with predominance in the right hemisphere and left frontal lobe. These findings provide a starting point for increasing our understanding of the complex relationships between cerebral activation and cardiovascular functioning involved in regulating blood pressure changes.

Phase-I monitoring of standard deviations in multistage linear profiles

NASA Astrophysics Data System (ADS)

Kalaei, Mahdiyeh; Soleimani, Paria; Niaki, Seyed Taghi Akhavan; Atashgar, Karim

2018-03-01

In most modern manufacturing systems, products are often the output of some multistage processes. In these processes, the stages are dependent on each other, where the output quality of each stage depends also on the output quality of the previous stages. This property is called the cascade property. Although there are many studies in multistage process monitoring, there are fewer works on profile monitoring in multistage processes, especially on the variability monitoring of a multistage profile in Phase-I for which no research is found in the literature. In this paper, a new methodology is proposed to monitor the standard deviation involved in a simple linear profile designed in Phase I to monitor multistage processes with the cascade property. To this aim, an autoregressive correlation model between the stages is considered first. Then, the effect of the cascade property on the performances of three types of T 2 control charts in Phase I with shifts in standard deviation is investigated. As we show that this effect is significant, a U statistic is next used to remove the cascade effect, based on which the investigated control charts are modified. Simulation studies reveal good performances of the modified control charts.

Realization of station for testing asynchronous three-phase motors

NASA Astrophysics Data System (ADS)

Wróbel, A.; Surma, W.

2016-08-01

Nowadays, you cannot imagine the construction and operation of machines without the use of electric motors [13-15]. The proposed position is designed to allow testing of asynchronous three-phase motors. The position consists of a tested engine and the engine running as a load, both engines combined with a mechanical clutch [2]. The value of the load is recorded by measuring shaft created with Strain Gauge Bridge. This concept will allow to study the basic parameters of the engines, visualization motor parameters both vector and scalar controlled, during varying load drive system. In addition, registration during the variable physical parameters of the working electric motor, controlled by a frequency converter or controlled by a contactor will be possible. Position is designed as a teaching and research position to characterize the engines. It will be also possible selection of inverter parameters.

Phase-Amplitude Response Functions for Transient-State Stimuli

PubMed Central

2013-01-01

Abstract The phase response curve (PRC) is a powerful tool to study the effect of a perturbation on the phase of an oscillator, assuming that all the dynamics can be explained by the phase variable. However, factors like the rate of convergence to the oscillator, strong forcing or high stimulation frequency may invalidate the above assumption and raise the question of how is the phase variation away from an attractor. The concept of isochrons turns out to be crucial to answer this question; from it, we have built up Phase Response Functions (PRF) and, in the present paper, we complete the extension of advancement functions to the transient states by defining the Amplitude Response Function (ARF) to control changes in the transversal variables. Based on the knowledge of both the PRF and the ARF, we study the case of a pulse-train stimulus, and compare the predictions given by the PRC-approach (a 1D map) to those given by the PRF-ARF-approach (a 2D map); we observe differences up to two orders of magnitude in favor of the 2D predictions, especially when the stimulation frequency is high or the strength of the stimulus is large. We also explore the role of hyperbolicity of the limit cycle as well as geometric aspects of the isochrons. Summing up, we aim at enlightening the contribution of transient effects in predicting the phase response and showing the limits of the phase reduction approach to prevent from falling into wrong predictions in synchronization problems. List of Abbreviations PRC phase response curve, phase resetting curve. PRF phase response function. ARF amplitude response function. PMID:23945295

Optical phase conjugation assisted scattering lens: variable focusing and 3D patterning

PubMed Central

Ryu, Jihee; Jang, Mooseok; Eom, Tae Joong; Yang, Changhuei; Chung, Euiheon

2016-01-01

Variable light focusing is the ability to flexibly select the focal distance of a lens. This feature presents technical challenges, but is significant for optical interrogation of three-dimensional objects. Numerous lens designs have been proposed to provide flexible light focusing, including zoom, fluid, and liquid-crystal lenses. Although these lenses are useful for macroscale applications, they have limited utility in micron-scale applications due to restricted modulation range and exacting requirements for fabrication and control. Here, we present a holographic focusing method that enables variable light focusing without any physical modification to the lens element. In this method, a scattering layer couples low-angle (transverse wave vector) components into a full angular spectrum, and a digital optical phase conjugation (DOPC) system characterizes and plays back the wavefront that focuses through the scattering layer. We demonstrate micron-scale light focusing and patterning over a wide range of focal distances of 22–51 mm. The interferometric nature of the focusing scheme also enables an aberration-free scattering lens. The proposed method provides a unique variable focusing capability for imaging thick specimens or selective photoactivation of neuronal networks. PMID:27049442

A genetic switch controls the production of flagella and toxins in Clostridium difficile

PubMed Central

2017-01-01

In the human intestinal pathogen Clostridium difficile, flagella promote adherence to intestinal epithelial cells. Flagellar gene expression also indirectly impacts production of the glucosylating toxins, which are essential to diarrheal disease development. Thus, factors that regulate the expression of the flgB operon will likely impact toxin production in addition to flagellar motility. Here, we report the identification a “flagellar switch” that controls the phase variable production of flagella and glucosylating toxins. The flagellar switch, located upstream of the flgB operon containing the early stage flagellar genes, is a 154 bp invertible sequence flanked by 21 bp inverted repeats. Bacteria with the sequence in one orientation expressed flagellum and toxin genes, produced flagella, and secreted the toxins (“flg phase ON”). Bacteria with the sequence in the inverse orientation were attenuated for flagellar and toxin gene expression, were aflagellate, and showed decreased toxin secretion (“flg phase OFF”). The orientation of the flagellar switch is reversible during growth in vitro. We provide evidence that gene regulation via the flagellar switch occurs post-transcription initiation and requires a C. difficile-specific regulatory factor to destabilize or degrade the early flagellar gene mRNA when the flagellar switch is in the OFF orientation. Lastly, through mutagenesis and characterization of flagellar phase locked isolates, we determined that the tyrosine recombinase RecV, which catalyzes inversion at the cwpV switch, is also responsible for inversion at the flagellar switch in both directions. Phase variable flagellar motility and toxin production suggests that these important virulence factors have both advantageous and detrimental effects during the course of infection. PMID:28346491

Integrated Digital Flight Control System for the Space Shuttle Orbiter

NASA Technical Reports Server (NTRS)

1973-01-01

The objectives of the integrated digital flight control system (DFCS) is to provide rotational and translational control of the space shuttle orbiter in all phases of flight: from launch ascent through orbit to entry and touchdown, and during powered horizontal flights. The program provides a versatile control system structure while maintaining uniform communications with other programs, sensors, and control effectors by using an executive routine/functional subroutine format. The program reads all external variables at a single point, copies them into its dedicated storage, and then calls the required subroutines in the proper sequence. As a result, the flight control program is largely independent of other programs in the computer complex and is equally insensitive to characteristics of the processor configuration. The integrated structure is described of the control system and the DFCS executive routine which embodies that structure. The input and output, including jet selection are included. Specific estimation and control algorithm are shown for the various mission phases: cruise (including horizontal powered flight), entry, on-orbit, and boost. Attitude maneuver routines that interface with the DFCS are included.

Controller for a High-Power, Brushless dc Motor

NASA Technical Reports Server (NTRS)

Fleming, David J.; Makdad, Terence A.

1987-01-01

Driving and braking torques controllable. Control circuit operates 7-kW, 45-lb-ft (61-N-m), three-phase, brushless dc motor in both motor and generator modes. In motor modes, energy from power source is pulse-width modulated to motor through modified "H-bridge" circuit, in generator mode, energy from motor is pulse-width modulated into bank of load resistors to provide variable braking torques. Circuit provides high-resolution torque control in both directions over wide range of speeds and torques. Tested successfully at bus voltages up to 200 Vdc and currents up to 45 A.

Interannual hydroclimatic variability and the 2009-2011 extreme ENSO phases in Colombia: from Andean glaciers to Caribbean lowlands

NASA Astrophysics Data System (ADS)

Bedoya-Soto, Juan Mauricio; Poveda, Germán; Trenberth, Kevin E.; Vélez-Upegui, Jorge Julián

2018-03-01

During 2009-2011, Colombia experienced extreme hydroclimatic events associated with the extreme phases of El Niño-Southern Oscillation (ENSO). Here, we study the dynamics of diverse land-atmosphere phenomena involved in such anomalous events at continental, regional, and local scales. Standardized anomalies of precipitation, 2-m temperature, total column water (TCW), volumetric soil water (VSW), temperature at 925 hPa, surface sensible heat (SSH), latent heat (SLH), evaporation (EVP), and liquid water equivalent thickness (LWET) are analyzed to assess atmosphere-land controls and relationships over tropical South America (TropSA) during 1986-2013 (long term) and 2009-2011 (ENSO extreme phases). An assessment of the interannual covariability between precipitation and 2-m temperature is performed using singular value decomposition (SVD) to identify the dominant spatiotemporal modes of hydroclimatic variability over the region's largest river basins (Amazon, Orinoco, Tocantins, Magdalena-Cauca, and Essequibo). ENSO, its evolution in time, and strong and consistent spatial structures emerge as the dominant mode of variability. In situ anomalies during both extreme phases of ENSO 2009-2011 over the Magdalena-Cauca River basins are linked at the continental scale. The ENSO-driven hydroclimatic effects extend from the diurnal cycle to interannual timescales, as reflected in temperature data from tropical glaciers and the rain-snow boundary in the highest peaks of the Central Andes of Colombia to river levels along the Caribbean lowlands of the Magdalena-Cauca River basin.

Obesity is associated with lack of inhibitory control and impaired heart rate variability reactivity and recovery in response to food stimuli.

PubMed

Spitoni, Grazia Fernanda; Ottaviani, Cristina; Petta, Anna Maria; Zingaretti, Pietro; Aragona, Massimiliano; Sarnicola, Antonio; Antonucci, Gabriella

2017-06-01

Recent theories compare obesity with addiction in terms of lack of inhibitory control in both clinical populations. The present study hypothesized impaired inhibition in obese patients reflected both in executive functions and reduced vagal tone (indexed by a decrease in heart rate variability; HRV) in response to food stimuli. Twenty-four inpatients with obesity (19 women) and 37 controls (24 women) underwent ECG monitoring during baseline, food stimuli viewing, and a recovery phase. Tests and questionnaires assessing inhibitory control and psychopathological dispositions were also administered. As hypothesized, patients were characterized by deficits in all the tests measuring inhibitory capacities. Results also show greater HRV reduction and impaired HRV recovery in response to food stimuli in obese patients compared to controls. The drive to eat experienced by obese patients in the absence of caloric need may rely on impairments in inhibitory and vagal functioning. Results are discussed in terms of implications for therapy. Copyright © 2017. Published by Elsevier B.V.

PDO and ENSO Sea Surface Temperature Anomalies Control Grassland Plant Production across the United States Great Plains

NASA Astrophysics Data System (ADS)

Parton, W. J.; Del Grosso, S. J.; Smith, W. K.; Chen, M.

2017-12-01

The El Nino Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) are multi-annual to multi-decadal climate patterns defined by ocean temperature anomalies that can strongly modulate climate variability. Here we evaluated the impacts of PDO and ENSO sea surface temperature (SST) anomalies on observed grassland above ground plant production (ANPP; 1940 to 2015), spring (April to July) cumulative actual evapotranspiration (iAET; 1900 to 2015) , and satellite-derived growing season (April to October) cumulative normalized difference vegetation index (iNDVI 1982 to 2015) across the United States Great Plains. The results showed that grassland ANPP is well correlated to iAET (r2=0.69) and iNDVI (r2=0.50 to 0.70) for the Cheyenne Wyoming and Northeastern Colorado long-term ANPP sites. At the site scale, during the negative phase of the PDO, we find ANPP is much lower (25%) and that variability of iAET, iNDVI, and ANPP are much higher (2 to 3 times) compared to the warm phase PDO. Further, we find there is a high frequency of below normal iAET when PDO and ENSO SST's are both negative, while there is a high frequency of above normal iAET when PDO and ENSO values are positive. At the regional scale, iAET, iNDVI, and modeled ANPP data sets show that plant production and iAET values are high in the southern Great Plains and low in the northern Great Plains when spring PDO and ENSO are both in the positive phase, while the opposite pattern is observed when both PDO and ENSO are both in the negative phase. Variability of iAET, iNDVI, and modeled ANPP are much higher in the central Great Plains during the negative phase PDO. We demonstrate clearly that the PDO and ENSO SST anomalies have large impacts on mean and variability of grassland plant production across the Great Plains.

Quaternion regularization in celestial mechanics, astrodynamics, and trajectory motion control. III

NASA Astrophysics Data System (ADS)

Chelnokov, Yu. N.

2015-09-01

The present paper1 analyzes the basic problems arising in the solution of problems of the optimum control of spacecraft (SC) trajectory motion (including the Lyapunov instability of solutions of conjugate equations) using the principle of the maximum. The use of quaternion models of astrodynamics is shown to allow: (1) the elimination of singular points in the differential phase and conjugate equations and in their partial analytical solutions; (2) construction of the first integrals of the new quaternion; (3) a considerable decrease of the dimensions of systems of differential equations of boundary value optimization problems with their simultaneous simplification by using the new quaternion variables related with quaternion constants of motion by rotation transformations; (4) construction of general solutions of differential equations for phase and conjugate variables on the sections of SC passive motion in the simplest and most convenient form, which is important for the solution of optimum pulse SC transfers; (5) the extension of the possibilities of the analytical investigation of differential equations of boundary value problems with the purpose of identifying the basic laws of optimum control and motion of SC; (6) improvement of the computational stability of the solution of boundary value problems; (7) a decrease in the required volume of computation.

Segmented nanowires displaying locally controllable properties

DOEpatents

Sutter, Eli Anguelova; Sutter, Peter Werner

2013-03-05

Vapor-liquid-solid growth of nanowires is tailored to achieve complex one-dimensional material geometries using phase diagrams determined for nanoscale materials. Segmented one-dimensional nanowires having constant composition display locally variable electronic band structures that are determined by the diameter of the nanowires. The unique electrical and optical properties of the segmented nanowires are exploited to form electronic and optoelectronic devices. Using gold-germanium as a model system, in situ transmission electron microscopy establishes, for nanometer-sized Au--Ge alloy drops at the tips of Ge nanowires (NWs), the parts of the phase diagram that determine their temperature-dependent equilibrium composition. The nanoscale phase diagram is then used to determine the exchange of material between the NW and the drop. The phase diagram for the nanoscale drop deviates significantly from that of the bulk alloy.

Optimal shifting control strategy in inertia phase of an automatic transmission for automotive applications

NASA Astrophysics Data System (ADS)

Meng, Fei; Tao, Gang; Zhang, Tao; Hu, Yihuai; Geng, Peng

2015-08-01

Shifting quality is a crucial factor in all parts of the automobile industry. To ensure an optimal gear shifting strategy with best fuel economy for a stepped automatic transmission, the controller should be designed to meet the challenge of lacking of a feedback sensor to measure the relevant variables. This paper focuses on a new kind of automatic transmission using proportional solenoid valve to control the clutch pressure, a speed difference of the clutch based control strategy is designed for the shift control during the inertia phase. First, the mechanical system is shown and the system dynamic model is built. Second, the control strategy is designed based on the characterization analysis of models which are derived from dynamics of the drive line and electro-hydraulic actuator. Then, the controller uses conventional Proportional-Integral-Derivative control theory, and a robust two-degree-of-freedom controller is also carried out to determine the optimal control parameters to further improve the system performance. Finally, the designed control strategy with different controller is implemented on a simulation model. The compared results show that the speed difference of clutch can track the desired trajectory well and improve the shift quality effectively.

Evaluation of response variables in computer-simulated virtual cataract surgery

NASA Astrophysics Data System (ADS)

Söderberg, Per G.; Laurell, Carl-Gustaf; Simawi, Wamidh; Nordqvist, Per; Skarman, Eva; Nordh, Leif

2006-02-01

We have developed a virtual reality (VR) simulator for phacoemulsification (phaco) surgery. The current work aimed at evaluating the precision in the estimation of response variables identified for measurement of the performance of VR phaco surgery. We identified 31 response variables measuring; the overall procedure, the foot pedal technique, the phacoemulsification technique, erroneous manipulation, and damage to ocular structures. Totally, 8 medical or optometry students with a good knowledge of ocular anatomy and physiology but naive to cataract surgery performed three sessions each of VR Phaco surgery. For measurement, the surgical procedure was divided into a sculpting phase and an evacuation phase. The 31 response variables were measured for each phase in all three sessions. The variance components for individuals and iterations of sessions within individuals were estimated with an analysis of variance assuming a hierarchal model. The consequences of estimated variabilities for sample size requirements were determined. It was found that generally there was more variability for iterated sessions within individuals for measurements of the sculpting phase than for measurements of the evacuation phase. This resulted in larger required sample sizes for detection of difference between independent groups or change within group, for the sculpting phase as compared to for the evacuation phase. It is concluded that several of the identified response variables can be measured with sufficient precision for evaluation of VR phaco surgery.

Immediate effects of a high-velocity spine manipulation in paraspinal muscles activity of nonspecific chronic low-back pain subjects.

PubMed

Bicalho, Eduardo; Setti, João Antônio Palma; Macagnan, Jones; Cano, José Luis Rivas; Manffra, Elisangela Ferretti

2010-10-01

High-velocity spinal manipulation is commonly adopted for treating chronic low-back pain (CLBP) and has been associated with changes in muscle activity, but the evidence is controversial. The aim of this study was to analyse the immediate effects of high-velocity spine manipulation on paraspinal activity during flexion-extension trunk movements. Forty nonspecific CLBP patients were randomised into two groups, manipulation (n = 20) and control (n = 20). While the manipulation group received high-velocity spine manipulation at the L4-L5 level, the control group remained lying in the same position. EMG-related variables, perceived pain intensity (100 mm VAS) and finger-floor distance were collected before and after spinal manipulation at the L4-L5 level. EMG surface signals from the right and left paraspinal muscles (L5-S1 level) were acquired during trunk flexion-extension cycles. EMG activity during the static relaxation phase was significantly reduced following intervention for the manipulation group but not for the control group. The extension-phase EMG activity was also reduced after manipulation, but the flexion-phase EMG levels remained unchanged. Accordingly, the percent changes in FRR and ERR were significantly larger for the manipulation group compared to the control. The results suggest that a high-velocity spinal manipulation is able to acutely reduce abnormal EMG activity during the full-flexion static phase and activation during the extension phase. Copyright 2010 Elsevier Ltd. All rights reserved.

Geochemical modeling of reactions and partitioning of trace metals and radionuclides during titration of contaminated acidic sediments.

PubMed

Zhang, Fan; Luo, Wensui; Parker, Jack C; Spalding, Brian P; Brooks, Scott C; Watson, David B; Jardine, Philip M; Gu, Baohua

2008-11-01

Many geochemical reactions that control aqueous metal concentrations are directly affected by solution pH. However, changes in solution pH are strongly buffered by various aqueous phase and solid phase precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior of the soil-solution system is thus critical to predict metal transport under variable pH conditions. This studywas undertaken to develop a practical generic geochemical modeling approach to predict aqueous and solid phase concentrations of metals and anions during conditions of acid or base additions. The method of Spalding and Spalding was utilized to model soil buffer capacity and pH-dependent cation exchange capacity by treating aquifer solids as a polyprotic acid. To simulate the dynamic and pH-dependent anion exchange capacity, the aquifer solids were simultaneously treated as a polyprotic base controlled by mineral precipitation/ dissolution reactions. An equilibrium reaction model that describes aqueous complexation, precipitation, sorption and soil buffering with pH-dependent ion exchange was developed using HydroGeoChem v5.0 (HGC5). Comparison of model results with experimental titration data of pH, Al, Ca, Mg, Sr, Mn, Ni, Co, and SO4(2-) for contaminated sediments indicated close agreement suggesting that the model could potentially be used to predictthe acid-base behavior of the sediment-solution system under variable pH conditions.

Refining Functional Behavioral Assessment: Analyzing the Separate and Combined Effects of Hypothesized Controlling Variables during Ongoing Classroom Routines

ERIC Educational Resources Information Center

Hoff, Kathryn E.; Ervin, Ruth A.; Friman, Patrick C.

2005-01-01

This article presents results from an investigation using functional assessment strategies in a general education classroom for an early adolescent diagnosed with ADHD/ODD. In the first phase of the assessment, data were collected from teacher interviews, student interviews, and direct observations to generate hypotheses regarding the association…

Methods Improvement of the Fluorescent Penetrant Inspection (FPI) Process.

DTIC Science & Technology

1980-10-01

also affect his ability. There has bieen recetnt eff’o to automiate V14. unfo~rtunatelyv, the humnan factors of’ F14I currentl lv cannot be replaced liY...control, and (6) human factors like variability of training, experience, and job interest. TECHNICAL APPROACH The objective of’ Phase II was to evaluate

The acute effects of heavy back squats on mechanical variables during a series of bilateral hops.

PubMed

Moir, Gavin L; Dale, Jonathan R; Dietrich, Wendy W

2009-07-01

The purpose of the present study was to investigate the acute effects of performing a heavy resistance exercise (HRE) protocol on the mechanical variables during a series of bilateral hops. In a block-randomized design, 10 strength trained men performed an HRE or a control treatment before performing 5 series of bilateral hops separated by 2 minutes of passive recovery. Each series of bilateral hops was performed for 15 seconds on a force platform with the subject hopping at a frequency of 2.0 Hz. From the vertical force trace, the vertical force during the countermovement phase of each hop, the negative displacement during the countermovement phase, and the vertical stiffness were calculated. The HRE treatment consisted of performing parallel back squats with 40, 50, 60, and 80% of each subject's 1-repetition maximum after a series of dynamic stretches. The control treatment consisted of the dynamic stretches only. No significant differences in any of the mechanical variables were reported after the 2 treatments (p > 0.05). There were no significant correlations between the absolute maximal strength values and the percent change in any of the mechanical variables after the 2 treatments. Despite the lack of significant changes reported for the group, there were some notable individual responses. It is possible that increases in vertical stiffness during bilateral hops can be achieved after an HRE protocol in certain individuals. However, practitioners should be aware of the specificity issues and the individual nature of the responses to such protocols.

Analysis of Interrelationships among Voluntary and Prosthetic Leg Joint Parameters Using Cyclograms.

PubMed

Jasni, Farahiyah; Hamzaid, Nur Azah; Mohd Syah, Nor Elleeiana; Chung, Tze Y; Abu Osman, Noor Azuan

2017-01-01

The walking mechanism of a prosthetic leg user is a tightly coordinated movement of several joints and limb segments. The interaction among the voluntary and mechanical joints and segments requires particular biomechanical insight. This study aims to analyze the inter-relationship between amputees' voluntary and mechanical coupled leg joints variables using cyclograms. From this analysis, the critical gait parameters in each gait phase were determined and analyzed if they contribute to a better powered prosthetic knee control design. To develop the cyclogram model, 20 healthy able-bodied subjects and 25 prosthesis and orthosis users (10 transtibial amputees, 5 transfemoral amputees, and 10 different pathological profiles of orthosis users) walked at their comfortable speed in a 3D motion analysis lab setting. The gait parameters (i.e., angle, moment and power for the ankle, knee and hip joints) were coupled to form 36 cyclograms relationship. The model was validated by quantifying the gait disparities of all the pathological walking by analyzing each cyclograms pairs using feed-forward neural network with backpropagation. Subsequently, the cyclogram pairs that contributed to the highest gait disparity of each gait phase were manipulated by replacing it with normal values and re-analyzed. The manipulated cyclograms relationship that showed highest improvement in terms of gait disparity calculation suggested that they are the most dominant parameters in powered-knee control. In case of transfemoral amputee walking, it was identified using this approach that at each gait sub-phase, the knee variables most responsible for closest to normal walking were: knee power during loading response and mid-stance, knee moment and knee angle during terminal stance phase, knee angle and knee power during pre-swing, knee angle at initial swing, and knee power at terminal swing. No variable was dominant during mid-swing phase implying natural pendulum effect of the lower limb between the initial and terminal swing phases. The outcome of this cyclogram adoption approach proposed an insight into the method of determining the causal effect of manipulating a particular joint's mechanical properties toward the joint behavior in an amputee's gait by determining the curve closeness, C, of the modified cyclogram curve to the normal conventional curve, to enable quantitative judgment of the effect of changing a particular parameter in the prosthetic leg gait.

Modelling and Model-Based-Designed PID Control of the JT-60SA Cryogenic System Using the Simcryogenics Library

NASA Astrophysics Data System (ADS)

Bonne, F.; Bonnay, P.; Hoa, C.; Mahoudeau, G.; Rousset, B.

2017-02-01

This papers deals with the Japan Torus-60 Super Advanced fusion experiment JT-60SA cryogenic system. A presentation of the JT-60SA cryogenic system model, from 300K to 4.4K -using the Matlab/Simulink/Simscape Simcryogenics library- will be given. As a first validation of our modelling strategy, the obtained operating point will be compared with the one obtained from HYSYS simulations. In the JT60-SA tokamak, pulsed heat loads are expected to be coming from the plasma and must be handled properly, using both appropriate refrigerator architecture and appropriate control model, to smooth the heat load. This paper presents model-based designed PID control schemes to control the helium mass inside the phase separator. The helium mass inside the phase separator as been chosen to be the variable of interest in the phase separator since it is independent of the pressure which can vary from 1 bar to 1.8 bar during load smoothing. Dynamics simulations will be shown to assess the legitimacy of the proposed strategy. This work is partially supported through the French National Research Agency (ANR), task agreement ANR-13-SEED-0005.

Compact nanomechanical plasmonic phase modulators [Ultracompact nano-mechanical plasmonic phase modulators

DOE PAGES

Dennis, B. S.; Haftel, M. I.; Czaplewski, D. A.; ...

2015-03-30

Highly confined optical energy in plasmonic devices is advancing miniaturization in photonics. However, for mode sizes approaching ≈10 nm, the energy increasingly shifts into the metal, raising losses and hindering active phase modulation. Here, we propose a nanoelectromechanical phase-modulation principle exploiting the extraordinarily strong dependence of the phase velocity of metal–insulator–metal gap plasmons on dynamically variable gap size. We experimentally demonstrate a 23-μm-long non-resonant modulator having a 1.5π rad range, with 1.7 dB excess loss at 780 nm. Analysis shows that by simultaneously decreasing the gap, length and width, an ultracompact-footprint π rad phase modulator can be realized. This ismore » achieved without incurring the extra loss expected for plasmons confined in a decreasing gap, because the increasing phase-modulation strength from a narrowing gap offsets rising propagation losses. Here, such small, high-density electrically controllable components may find applications in optical switch fabrics and reconfigurable plasmonic optics.« less

Differences in grip force control between young and late middle-aged adults.

PubMed

Zheng, Lianrong; Li, Kunyang; Wang, Qian; Chen, Wenhui; Song, Rong; Liu, Guanzheng

2017-09-01

Grip force control is a crucial function for human to guarantee the quality of life. To examine the effects of age on grip force control, 10 young adults and 11 late middle-aged adults participated in visually guided tracking tasks using different target force levels (25, 50, and 75% of the subject's maximal grip force). Multiple measures were used to evaluate the tracking performance during force rising phase and force maintenance phase. The measurements include the rise time, fuzzy entropy, mean force percentage, coefficient of variation, and target deviation ratio. The results show that the maximal grip force was significantly lower in the late middle-aged adults than in the young adults. The time of rising phase was systematically longer among late middle-aged adults. The fuzzy entropy is a useful indicator for quantitating the force variability of the grip force signal at higher force levels. These results suggest that the late middle-aged adults applied a compensatory strategy that allow allows for sufficient time to reach the required grip force and reduce the impact of the early and subtle degenerative changes in hand motor function.

Diagenetic and compositional controls of wettability in siliceous sedimentary rocks, Monterey Formation, California

NASA Astrophysics Data System (ADS)

Hill, Kristina M.

Modified imbibition tests were performed on 69 subsurface samples from Monterey Formation reservoirs in the San Joaquin Valley to measure wettability variation as a result of composition and silica phase change. Contact angle tests were also performed on 6 chert samples from outcrop and 3 nearly pure mineral samples. Understanding wettability is important because it is a key factor in reservoir fluid distribution and movement, and its significance rises as porosity and permeability decrease and fluid interactions with reservoir grain surface area increase. Although the low permeability siliceous reservoirs of the Monterey Formation are economically important and prolific, a greater understanding of factors that alter their wettability will help better develop them. Imbibition results revealed a strong trend of decreased wettability to oil with increased detrital content in opal-CT phase samples. Opal-A phase samples exhibited less wettability to oil than both opal-CT and quartz phase samples of similar detrital content. Subsurface reservoir samples from 3 oil fields were crushed to eliminate the effect of capillary pressure and cleansed of hydrocarbons to eliminate wettability alterations by asphaltene, then pressed into discs of controlled density. Powder discs were tested for wettability by dispensing a controlled volume of water and motor oil onto the surface and measuring the time required for each fluid to imbibe into the sample. The syringe and software of a CAM101 tensiometer were used to control the amount of fluid dispensed onto each sample, and imbibition completion times were determined by high-speed photography for water drops; oil drop imbibition was significantly slower and imbibition was timed and determined visually. Contact angle of water and oil drops on polished chert and mineral sample surfaces was determined by image analysis and the Young-Laplace equation. Oil imbibition was significantly slower with increased detrital composition and faster with increased silica content in opal-CT and quartz phase samples, implying decreased wettability to oil with increased detrital (clay) content. However, contact angle tests showed that opal-CT is more wetting to oil with increased detritus and results for oil on quartz-phase samples were inconsistent between different proxies for detritus over their very small compositional range. Water contact angle trends also showed inconsistent wetting trends compared to imbibition tests. We believe this is because the small range in bulk detrital composition between the "pure" samples used in contact angle tests was close to analytical error and because small-scale spatial compositional variability may be significant enough to effect wettability. These experiments show that compositional variables significantly affect wettability, outweighing the effect of silica phase.

Abnormal gait pattern emerges during curved trajectories in high-functioning Parkinsonian patients walking in line at normal speed

PubMed Central

Godi, Marco; Giardini, Marica; Arcolin, Ilaria; Nardone, Antonio; Giordano, Andrea; Schieppati, Marco

2018-01-01

Background Several patients with Parkinson´s disease (PD) can walk normally along straight trajectories, and impairment in their stride length and cadence may not be easily discernible. Do obvious abnormalities occur in these high-functioning patients when more challenging trajectories are travelled, such as circular paths, which normally implicate a graded modulation in the duration of the interlimb gait cycle phases? Methods We compared a cohort of well-treated mildly to moderately affected PD patients to a group of age-matched healthy subjects (HS), by deliberately including HS spontaneously walking at the same speed of the patients with PD. All participants performed, in random order: linear and circular walking (clockwise and counter-clockwise) at self-selected speed. By means of pressure-sensitive insoles, we recorded walking speed, cadence, duration of single support, double support, swing phase, and stride time. Stride length-cadence relationships were built for linear and curved walking. Stride-to-stride variability of temporal gait parameters was also estimated. Results Walking speed, cadence or stride length were not different between PD and HS during linear walking. Speed, cadence and stride length diminished during curved walking in both groups, stride length more in PD than HS. In PD compared to HS, the stride length-cadence relationship was altered during curved walking. Duration of the double-support phase was also increased during curved walking, as was variability of the single support, swing phase and double support phase. Conclusion The spatio-temporal gait pattern and variability are significantly modified in well-treated, high-functioning patients with PD walking along circular trajectories, even when they exhibit no changes in speed in straight-line walking. The increased variability of the gait phases during curved walking is an identifying characteristic of PD. We discuss our findings in term of interplay between control of balance and of locomotor progression: the former is challenged by curved trajectories even in high-functioning patients, while the latter may not be critically affected. PMID:29750815

Evolutionary Design of Controlled Structures

NASA Technical Reports Server (NTRS)

Masters, Brett P.; Crawley, Edward F.

1997-01-01

Basic physical concepts of structural delay and transmissibility are provided for simple rod and beam structures. Investigations show the sensitivity of these concepts to differing controlled-structures variables, and to rational system modeling effects. An evolutionary controls/structures design method is developed. The basis of the method is an accurate model formulation for dynamic compensator optimization and Genetic Algorithm based updating of sensor/actuator placement and structural attributes. One and three dimensional examples from the literature are used to validate the method. Frequency domain interpretation of these controlled structure systems provide physical insight as to how the objective is optimized and consequently what is important in the objective. Several disturbance rejection type controls-structures systems are optimized for a stellar interferometer spacecraft application. The interferometric designs include closed loop tracking optics. Designs are generated for differing structural aspect ratios, differing disturbance attributes, and differing sensor selections. Physical limitations in achieving performance are given in terms of average system transfer function gains and system phase loss. A spacecraft-like optical interferometry system is investigated experimentally over several different optimized controlled structures configurations. Configurations represent common and not-so-common approaches to mitigating pathlength errors induced by disturbances of two different spectra. Results show that an optimized controlled structure for low frequency broadband disturbances achieves modest performance gains over a mass equivalent regular structure, while an optimized structure for high frequency narrow band disturbances is four times better in terms of root-mean-square pathlength. These results are predictable given the nature of the physical system and the optimization design variables. Fundamental limits on controlled performance are discussed based on the measured and fit average system transfer function gains and system phase loss.

Stance controlled knee flexion improves stimulation driven walking after spinal cord injury

PubMed Central

2013-01-01

Background Functional neuromuscular stimulation (FNS) restores walking function after paralysis from spinal cord injury via electrical activation of muscles in a coordinated fashion. Combining FNS with a controllable orthosis to create a hybrid neuroprosthesis (HNP) has the potential to extend walking distance and time by mechanically locking the knee joint during stance to allow knee extensor muscle to rest with stimulation turned off. Recent efforts have focused on creating advanced HNPs which couple joint motion (e.g., hip and knee or knee and ankle) to improve joint coordination during swing phase while maintaining a stiff-leg during stance phase. Methods The goal of this study was to investigate the effects of incorporating stance controlled knee flexion during loading response and pre-swing phases on restored gait. Knee control in the HNP was achieved by a specially designed variable impedance knee mechanism (VIKM). One subject with a T7 level spinal cord injury was enrolled and served as his own control in examining two techniques to restore level over-ground walking: FNS-only (which retained a stiff knee during stance) and VIKM-HNP (which allowed controlled knee motion during stance). The stimulation pattern driving the walking motion remained the same for both techniques; the only difference was that knee extensor stimulation was constant during stance with FNS-only and modulated together with the VIKM to control knee motion during stance with VIKM-HNP. Results Stance phase knee angle was more natural during VIKM-HNP gait while knee hyperextension persisted during stiff-legged FNS-only walking. During loading response phase, vertical ground reaction force was less impulsive and instantaneous gait speed was increased with VIKM-HNP, suggesting that knee flexion assisted in weight transfer to the leading limb. Enhanced knee flexion during pre-swing phase also aided flexion during swing, especially when response to stimulation was compromised. Conclusions These results show the potential advantages of incorporating stance controlled knee flexion into a hybrid neuroprosthesis for walking. The addition of such control to FNS driven walking could also enable non-level walking tasks such as uneven terrain, slope navigation and stair descent where controlled knee flexion during weight bearing is critical. PMID:23826711

Application of the generalized reduced gradient method to conceptual aircraft design

NASA Technical Reports Server (NTRS)

Gabriele, G. A.

1984-01-01

The complete aircraft design process can be broken into three phases of increasing depth: conceptual design, preliminary design, and detail design. Conceptual design consists primarily of developing general arrangements and selecting the configuration that optimally satisfies all mission requirements. The result of the conceptual phase is a conceptual baseline configuration that serves as the starting point for the preliminary design phase. The conceptual design of an aircraft involves a complex trade-off of many independent variables that must be investigated before deciding upon the basic configuration. Some of these variables are discrete (number of engines), some represent different configurations (canard vs conventional tail) and some may represent incorporation of new technologies (aluminum vs composite materials). At Lockheed-Georgia, the sizing program is known as GASP (Generalized Aircraft Sizing Program). GASP is a large program containing analysis modules covering the many different disciplines involved fin defining the aricraft, such as aerodynamics, structures, stability and control, mission performance, and cost. These analysis modules provide first-level estimates the aircraft properties that are derived from handbook, experimental, and historical sources.

Increased QT interval variability index in acute alcohol withdrawal.

PubMed

Bär, Karl-Jürgen; Boettger, Michael Karl; Koschke, Mandy; Boettger, Silke; Grotelüschen, Marei; Voss, Andreas; Yeragani, Vikram K

2007-07-10

Acute alcohol withdrawal is associated with increased cardiovascular mortality, most likely due to cardiac arrhythmias. As the QT interval reflects the most critical phase for the generation of reentry and thus for arrhythmia, we examined QT variability in patients suffering from acute alcohol withdrawal. High resolution electrocardiographic recordings were performed in 18 male unmedicated patients suffering from acute alcohol withdrawal, 18 matched controls and 15 abstained alcoholics. From these, parameters of beat-to-beat heart rate and QT variability such as approximate entropy and QT variability index (QTvi) were calculated. Measures were correlated with the severity of withdrawal symptoms and with serum electrolyte concentrations. Heart rate and QTvi were significantly increased in acute alcohol withdrawal. Abstained alcoholics did not significantly differ from controls. While QTvi correlated with the severity of alcohol withdrawal symptoms, the mean QT interval duration showed an inverse relationship with serum potassium concentrations. Our data indicate increased QT variability and thus increased repolarization lability in acute alcohol withdrawal. This might add to the elevated risk for serious cardiac arrhythmias. In part, these changes might be related to increased cardiac sympathetic activity or low potassium, thus suggesting the latter as possible targets for adjuvant pharmacological therapy during withdrawal.

Body temperature, activity and melatonin profiles in adults with attention-deficit/hyperactivity disorder and delayed sleep: a case-control study.

PubMed

Bijlenga, Denise; Van Someren, Eus J W; Gruber, Reut; Bron, Tannetje I; Kruithof, I Femke; Spanbroek, Elise C A; Kooij, J J Sandra

2013-12-01

Irregular sleep-wake patterns and delayed sleep times are common in adults with attention-deficit/hyperactivity disorder, but mechanisms underlying these problems are unknown. The present case-control study examined whether circadian abnormalities underlie these sleep problems in a naturalistic home setting. We included 12 medication-naïve patients with attention-deficit/hyperactivity disorder and delayed sleep phase syndrome, and 12 matched healthy controls. We examined associations between sleep/wake rhythm in attention-deficit/hyperactivity disorder and circadian parameters (i.e. salivary melatonin concentrations, core and skin temperatures, and activity patterns) of the patients and controls during five consecutive days and nights. Daily bedtimes were more variable within patients compared with controls (F = 8.19, P < 0.001), but melatonin profiles were equally stable within individuals. Dim-light melatonin onset was about 1.5 h later in the patient group (U = 771, Z = -4.63, P < 0.001). Patients slept about 1 h less on nights before work days compared with controls (F = 11.21, P = 0.002). The interval between dim-light melatonin onset and sleep onset was on average 1 h longer in patients compared with controls (U = 1117, Z = -2.62, P = 0.009). This interval was even longer in patients with extremely late chronotype. Melatonin, activity and body temperatures were delayed to comparable degrees in patients. Overall temperatures were lower in patients than controls. Sleep-onset difficulties correlated with greater distal-proximal temperature gradient (DPG; i.e. colder hands, r(2)  = -0.32, P = 0.028) in patients. Observed day-to-day bedtime variability of individuals with attention-deficit/hyperactivity disorder and delayed sleep phase syndrome were not reflected in their melatonin profiles. Irregular sleep-wake patterns and delayed sleep in individuals with attention-deficit/hyperactivity disorder and delayed sleep phase syndrome are associated with delays and dysregulations of the core and skin temperatures. © 2013 European Sleep Research Society.

Production of sugarcane and tropical grasses as a renewable energy source. Second annual report, 1978-1979

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

Not Available

1979-01-01

Reseach continued on tropical grasses from Saccharum and related genera as sources of intensively-produced, solar-dried biomass. Categories of candidate grasses include short-, intermediate-, and long-rotation species. These categories are based on the time interval required for maximum dry matter production, and on future management requirements of energy crops for intensive co-production with food crop commodities. Year 1 studies at the greenhouse and field-plot levels were continued and broadened during Year 2. This included candidate screening, importation and quarantine of new clones, breeding, controlled nitrogen and water regimes, chemical growth control, tissue expansion and maturation control, seeding rates, harvest frequency, andmore » variable row spacing. Second-year studies were extended to the project's field-scale and mechanized-harvest phases. These include initial economic anayses for the short-rotation phases. These include initial economic analyses for the short-rotation category of candidate species.« less

Nanometer-scale mapping of irreversible electrochemical nucleation processes on solid Li-ion electrolytes

NASA Astrophysics Data System (ADS)

Kumar, Amit; Arruda, Thomas M.; Tselev, Alexander; Ivanov, Ilia N.; Lawton, Jamie S.; Zawodzinski, Thomas A.; Butyaev, Oleg; Zayats, Sergey; Jesse, Stephen; Kalinin, Sergei V.

2013-04-01

Electrochemical processes associated with changes in structure, connectivity or composition typically proceed via new phase nucleation with subsequent growth of nuclei. Understanding and controlling reactions requires the elucidation and control of nucleation mechanisms. However, factors controlling nucleation kinetics, including the interplay between local mechanical conditions, microstructure and local ionic profile remain inaccessible. Furthermore, the tendency of current probing techniques to interfere with the original microstructure prevents a systematic evaluation of the correlation between the microstructure and local electrochemical reactivity. In this work, the spatial variability of irreversible nucleation processes of Li on a Li-ion conductive glass-ceramics surface is studied with ~30 nm resolution. An increased nucleation rate at the boundaries between the crystalline AlPO4 phase and amorphous matrix is observed and attributed to Li segregation. This study opens a pathway for probing mechanisms at the level of single structural defects and elucidation of electrochemical activities in nanoscale volumes.

Nanometer-scale mapping of irreversible electrochemical nucleation processes on solid Li-ion electrolytes.

PubMed

Kumar, Amit; Arruda, Thomas M; Tselev, Alexander; Ivanov, Ilia N; Lawton, Jamie S; Zawodzinski, Thomas A; Butyaev, Oleg; Zayats, Sergey; Jesse, Stephen; Kalinin, Sergei V

2013-01-01

Electrochemical processes associated with changes in structure, connectivity or composition typically proceed via new phase nucleation with subsequent growth of nuclei. Understanding and controlling reactions requires the elucidation and control of nucleation mechanisms. However, factors controlling nucleation kinetics, including the interplay between local mechanical conditions, microstructure and local ionic profile remain inaccessible. Furthermore, the tendency of current probing techniques to interfere with the original microstructure prevents a systematic evaluation of the correlation between the microstructure and local electrochemical reactivity. In this work, the spatial variability of irreversible nucleation processes of Li on a Li-ion conductive glass-ceramics surface is studied with ~30 nm resolution. An increased nucleation rate at the boundaries between the crystalline AlPO4 phase and amorphous matrix is observed and attributed to Li segregation. This study opens a pathway for probing mechanisms at the level of single structural defects and elucidation of electrochemical activities in nanoscale volumes.

Nanometer-scale mapping of irreversible electrochemical nucleation processes on solid Li-ion electrolytes

PubMed Central

Kumar, Amit; Arruda, Thomas M.; Tselev, Alexander; Ivanov, Ilia N.; Lawton, Jamie S.; Zawodzinski, Thomas A.; Butyaev, Oleg; Zayats, Sergey; Jesse, Stephen; Kalinin, Sergei V.

2013-01-01

Electrochemical processes associated with changes in structure, connectivity or composition typically proceed via new phase nucleation with subsequent growth of nuclei. Understanding and controlling reactions requires the elucidation and control of nucleation mechanisms. However, factors controlling nucleation kinetics, including the interplay between local mechanical conditions, microstructure and local ionic profile remain inaccessible. Furthermore, the tendency of current probing techniques to interfere with the original microstructure prevents a systematic evaluation of the correlation between the microstructure and local electrochemical reactivity. In this work, the spatial variability of irreversible nucleation processes of Li on a Li-ion conductive glass-ceramics surface is studied with ~30 nm resolution. An increased nucleation rate at the boundaries between the crystalline AlPO4 phase and amorphous matrix is observed and attributed to Li segregation. This study opens a pathway for probing mechanisms at the level of single structural defects and elucidation of electrochemical activities in nanoscale volumes. PMID:23563856

Stochastic many-particle model for LFP electrodes

NASA Astrophysics Data System (ADS)

Guhlke, Clemens; Gajewski, Paul; Maurelli, Mario; Friz, Peter K.; Dreyer, Wolfgang

2018-02-01

In the framework of non-equilibrium thermodynamics, we derive a new model for many-particle electrodes. The model is applied to LiFePO4 (LFP) electrodes consisting of many LFP particles of nanometer size. The phase transition from a lithium-poor to a lithium-rich phase within LFP electrodes is controlled by both different particle sizes and surface fluctuations leading to a system of stochastic differential equations. An explicit relation between battery voltage and current controlled by the thermodynamic state variables is derived. This voltage-current relation reveals that in thin LFP electrodes lithium intercalation from the particle surfaces into the LFP particles is the principal rate-limiting process. There are only two constant kinetic parameters in the model describing the intercalation rate and the fluctuation strength, respectively. The model correctly predicts several features of LFP electrodes, viz. the phase transition, the observed voltage plateaus, hysteresis and the rate-limiting capacity. Moreover we study the impact of both the particle size distribution and the active surface area on the voltage-charge characteristics of the electrode. Finally we carefully discuss the phase transition for varying charging/discharging rates.

Temporal dynamics of circadian phase shifting response to consecutive night shifts in healthcare workers: role of light-dark exposure.

PubMed

Stone, Julia E; Sletten, Tracey L; Magee, Michelle; Ganesan, Saranea; Mulhall, Megan D; Collins, Allison; Howard, Mark; Lockley, Steven W; Rajaratnam, Shantha M W

2018-06-01

Shift work is highly prevalent and is associated with significant adverse health impacts. There is substantial inter-individual variability in the way the circadian clock responds to changing shift cycles. The mechanisms underlying this variability are not well understood. We tested the hypothesis that light-dark exposure is a significant contributor to this variability; when combined with diurnal preference, the relative timing of light exposure accounted for 71% of individual variability in circadian phase response to night shift work. These results will drive development of personalised approaches to manage circadian disruption among shift workers and other vulnerable populations to potentially reduce the increased risk of disease in these populations. Night shift workers show highly variable rates of circadian adaptation. This study examined the relationship between light exposure patterns and the magnitude of circadian phase resetting in response to night shift work. In 21 participants (nursing and medical staff in an intensive care unit) circadian phase was measured using 6-sulphatoxymelatonin at baseline (day/evening shifts or days off) and after 3-4 consecutive night shifts. Daily light exposure was examined relative to individual circadian phase to quantify light intensity in the phase delay and phase advance portions of the light phase response curve (PRC). There was substantial inter-individual variability in the direction and magnitude of phase shift after three or four consecutive night shifts (mean phase delay -1:08 ± 1:31 h; range -3:43 h delay to +3:07 h phase advance). The relative difference in the distribution of light relative to the PRC combined with diurnal preference accounted for 71% of the variability in phase shift. Regression analysis incorporating these factors estimated phase shift to within ±60 min in 85% of participants. No participants met criteria for partial adaptation to night work after three or four consecutive night shifts. Our findings provide evidence that the phase resetting that does occur is based on individual light exposure patterns relative to an individual's baseline circadian phase. Thus, a 'one size fits all' approach to promoting adaptation to shift work using light therapy, implemented without knowledge of circadian phase, may not be efficacious for all individuals. © 2018 Monash University. The Journal of Physiology © 2018 The Physiological Society.

Effect of deformation induced nucleation and phase mixing, a two phase model for the ductile deformation of rocks.

NASA Astrophysics Data System (ADS)

Bevillard, Benoit; Richard, Guillaume; Raimbourg, Hugues

2017-04-01

Rocks are complex materials and particularly their rheological behavior under geological stresses remains a long-standing question in geodynamics. To test large scale lithosphere dynamics numerical modeling is the main tool but encounter substantial difficulties to account for this complexity. One major unknown is the origin and development of the localization of deformation. This localization is observed within a large range of scales and is commonly characterized by sharp grain size reduction. These considerations argues for a control of the microscopical scale over the largest ones through one predominant variable: the mean grain-size. However, the presence of second phase and broad grain-size distribution may also have a important impact on this phenomenon. To address this question, we built a model for ductile rocks deformation based on the two-phase damage theory of Bercovici & Ricard 2012. We aim to investigate the role of grain-size reduction but also phase mixing on strain localization. Instead of considering a Zener-pining effect on damage evolution, we propose to take into account the effect of the grain-boundary sliding (GBS)-induced nucleation mechanism which is better supported by experimental or natural observations (Precigout et al 2016). This continuum theory allows to represent a two mineral phases aggregate with explicit log-normal grain-size distribution as a reasonable approximation for polymineralic rocks. Quantifying microscopical variables using a statistical approach may allow for calibration at small (experimental) scale. The general set of evolutions equations remains up-scalable provided some conditions on the homogenization scale. Using the interface density as a measure of mixture quality, we assume unlike Bercovici & Ricard 2012 that it may depend for some part on grain-size . The grain-size independent part of it is being represented by a "contact fraction" variable, whose evolution may be constrained by the dominant deformation mechanism. To derive the related evolution equations and account for the interdependence of thermodynamic state variables, we use Onsager's thermodynamic extremum principle. Eventually, we solve for our set of equations using an Anorthite/Pyroxene gabbroic composition. The results are used to discuss the interaction between grain-size reduction and phase mixing on strain localization on several simple cases. Bercovici D, Ricard Y (2012) Mechanisms for the generation of plate tectonics by two phase grain damage and pinning. Physics of the Earth and Planetary Interiors 202-203:27-55 Precigout J, Stunitz H (2016) Evidence of phase nucleation during olivine diffusion creep: A new perspective for mantle strain localisation. Earth and Planetary Science Letters 405:94-105

Brain Oscillations Elicited by the Cold Pressor Test: A Putative Index of Untreated Essential Hypertension

PubMed Central

Tsaltas, Eleftheria; Koroboki, Eleni; Alevizaki, Maria; Angelopoulos, Elias; Dimopoulos, Meletios-Athanasios; Papageorgiou, Charalabos; Zakopoulos, Nikolaos

2017-01-01

Objective Essential hypertension is associated with reduced pain sensitivity of unclear aetiology. This study explores this issue using the Cold Pressor Test (CPT), a reliable pain/stress model, comparing CPT-related EEG activity in first episode hypertensives and controls. Method 22 untreated hypertensives and 18 matched normotensives underwent 24-hour ambulatory blood pressure monitoring (ABPM). EEG recordings were taken before, during, and after CPT exposure. Results Significant group differences in CPT-induced EEG oscillations were covaried with the most robust cardiovascular differentiators by means of a Canonical Analysis. Positive correlations were noted between ABPM variables and Delta (1–4 Hz) oscillations during the tolerance phase; in high-alpha (10–12 Hz) oscillations during the stress unit and posttest phase; and in low-alpha (8–10 Hz) oscillations during CPT phases overall. Negative correlations were found between ABPM variables and Beta2 oscillations (16.5–20 Hz) during the posttest phase and Gamma (28.5–45 Hz) oscillations during the CPT phases overall. These relationships were localised at several sites across the cerebral hemispheres with predominance in the right hemisphere and left frontal lobe. Conclusions These findings provide a starting point for increasing our understanding of the complex relationships between cerebral activation and cardiovascular functioning involved in regulating blood pressure changes. PMID:28573048

Liquid behavior of cross-linked actin bundles.

PubMed

Weirich, Kimberly L; Banerjee, Shiladitya; Dasbiswas, Kinjal; Witten, Thomas A; Vaikuntanathan, Suriyanarayanan; Gardel, Margaret L

2017-02-28

The actin cytoskeleton is a critical regulator of cytoplasmic architecture and mechanics, essential in a myriad of physiological processes. Here we demonstrate a liquid phase of actin filaments in the presence of the physiological cross-linker, filamin. Filamin condenses short actin filaments into spindle-shaped droplets, or tactoids, with shape dynamics consistent with a continuum model of anisotropic liquids. We find that cross-linker density controls the droplet shape and deformation timescales, consistent with a variable interfacial tension and viscosity. Near the liquid-solid transition, cross-linked actin bundles show behaviors reminiscent of fluid threads, including capillary instabilities and contraction. These data reveal a liquid droplet phase of actin, demixed from the surrounding solution and dominated by interfacial tension. These results suggest a mechanism to control organization, morphology, and dynamics of the actin cytoskeleton.

Survey of current and emerging technologies for biological contamination control

NASA Astrophysics Data System (ADS)

Frick, Andreas; Mogul, Rakesh

2012-07-01

This study will survey current and emerging technologies for biological contamination control within the context of planetary protection. Using a systems analysis approach, our objective is to compare various implementation variables across tasks ranging from surface cleaning to full-system sterilization for spacecraft and spacecraft components. Methods reviewed include vapor-phase hydrogen peroxide, plasma-phase sterilants such as oxygen and hydrogen peroxide, dry heat, laser-based techniques, supercritical carbon dioxide-based methods, and advanced bio-barriers. These methods will be evaluated in relation to relevant mission architectures and will address aspects of sample return missions. Results from this study, therefore, will offer new insights into the present-day engineering capabilities and future developmental concerns for missions targeting icy satellites, Mars, and other locations of astrochemical and astrobiological significance.

Final Technical Report: The effects of climate, forest age, and disturbance history on carbon and water processes at AmeriFlux sites across gradients in Pacific Northwest forests

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

Law, Beverly E.

Investigate the effects of disturbance and climate variables on processes controlling carbon and water processes at AmeriFlux cluster sites in semi-arid and mesic forests in Oregon. The observations were made at three existing and productive AmeriFlux research sites that represent climate and disturbance gradients as a natural experiment of the influence of climatic and hydrologic variability on carbon sequestration and resulting atmospheric CO 2 feedback that includes anomalies during the warm/ dry phase of the Pacific Decadal Oscillation.

Chaos, ergodic convergence, and fractal instability for a thermostated canonical harmonic oscillator

NASA Astrophysics Data System (ADS)

Hoover, Wm. G.; Hoover, Carol G.; Isbister, Dennis J.

2001-02-01

The authors thermostat a qp harmonic oscillator using the two additional control variables ζ and ξ to simulate Gibbs' canonical distribution. In contrast to the motion of purely Hamiltonian systems, the thermostated oscillator motion is completely ergodic, covering the full four-dimensional \\{q,p,ζ,ξ\\} phase space. The local Lyapunov spectrum (instantaneous growth rates of a comoving corotating phase-space hypersphere) exhibits singularities like those found earlier for Hamiltonian chaos, reinforcing the notion that chaos requires kinetic-as opposed to statistical-study, both at and away from equilibrium. The exponent singularities appear to have a fractal character.

Atmospheric controls on the precipitation isotopes over the Andaman Islands, Bay of Bengal

PubMed Central

Chakraborty, S.; Sinha, N.; Chattopadhyay, R.; Sengupta, S.; Mohan, P. M.; Datye, A.

2016-01-01

Isotopic analysis of precipitation over the Andaman Island, Bay of Bengal was carried out for the year 2012 and 2013 in order to study the atmospheric controls on rainwater isotopic variations. The oxygen and hydrogen isotopic compositions are typical of the tropical marine sites but show significant variations depending on the ocean-atmosphere conditions; maximum depletion was observed during the tropical cyclones. The isotopic composition of rainwater seems to be controlled by the dynamical nature of the moisture rather than the individual rain events. Precipitation isotopes undergo systematic depletions in response to the organized convection occurring over a large area and are modulated by the integrated effect of convective activities. Precipitation isotopes appear to be linked with the monsoon intraseasonal variability in addition to synoptic scale fluctuations. During the early to mid monsoon the amount effect arose primarily due to rain re-evaporation but in the later phase it was driven by moisture convergence rather than evaporation. Amount effect had distinct characteristics in these two years, which appeared to be modulated by the intraseasonal variability of monsoon. It is shown that the variable nature of amount effect limits our ability to reconstruct the past-monsoon rainfall variability on annual to sub-annual time scale. PMID:26806683

Liquid crystal optics for communications, signal processing and 3-D microscopic imaging

NASA Astrophysics Data System (ADS)

Khan, Sajjad Ali

This dissertation proposes, studies and experimentally demonstrates novel liquid crystal (LC) optics to solve challenging problems in RF and photonic signal processing, freespace and fiber optic communications and microscopic imaging. These include free-space optical scanners for military and optical wireless applications, variable fiber-optic attenuators for optical communications, photonic control techniques for phased array antennas and radar, and 3-D microscopic imaging. At the heart of the applications demonstrated in this thesis are LC devices that are non-pixelated and can be controlled either electrically or optically. Instead of the typical pixel-by-pixel control as is custom in LC devices, the phase profile across the aperture of these novel LC devices is varied through the use of high impedance layers. Due to the presence of the high impedance layer, there forms a voltage gradient across the aperture of such a device which results in a phase gradient across the LC layer which in turn is accumulated by the optical beam traversing through this LC device. The geometry of the electrical contacts that are used to apply the external voltage will define the nature of the phase gradient present across the optical beam. In order to steer a laser beam in one angular dimension, straight line electrical contacts are used to form a one dimensional phase gradient while an annular electrical contact results in a circularly symmetric phase profile across the optical beam making it suitable for focusing the optical beam. The geometry of the electrical contacts alone is not sufficient to form the linear and the quadratic phase profiles that are required to either deflect or focus an optical beam. Clever use of the phase response of a typical nematic liquid crystal (NLC) is made such that the linear response region is used for the angular beam deflection while the high voltage quadratic response region is used for focusing the beam. Employing an NLC deflector, a device that uses the linear angular deflection, laser beam steering is demonstrated in two orthogonal dimensions whereas an NLC lens is used to address the third dimension to complete a three dimensional (3-D) scanner. Such an NLC deflector was then used in a variable optical attenuator (VOA), whereby a laser beam coupled between two identical single mode fibers (SMF) was mis-aligned away from the output fiber causing the intensity of the output coupled light to decrease as a function of the angular deflection. Since the angular deflection is electrically controlled, hence the VOA operation is fairly simple and repeatable. An extension of this VOA for wavelength tunable operation is also shown in this dissertation. (Abstract shortened by UMI.)

Impact of nursing interventions on adherence to treatment with antituberculosis drugs in children and young people: A non-randomized controlled trial.

PubMed

Guix-Comellas, Eva Maria; Rozas-Quesada, Librada; Velasco-Arnaiz, Eneritz; Ferres-Canals, Ariadna; Estrada-Masllorens, Joan Maria; Force-Sanmartín, Enriqueta; Noguera-Julian, Antoni

2018-05-03

To evaluate the association of a new nursing intervention on the adherence to antituberculosis treatment in a pediatric cohort (<18 years). Tuberculosis remains a public health problem worldwide. The risk of developing tuberculosis after primary infection and its severity are higher in children. Proper adherence to antituberculosis treatment is critical for disease control. Non-randomized controlled trial; Phase 1, retrospective (2011-2013), compared with Phase 2, prospective with intervention (2015-2016), in a referral center for pediatric tuberculosis in Spain (NCT03230409). A total of 359 patients who received antituberculosis drugs after close contact with a smear-positive patient (primary chemoprophylaxis) or were treated for latent tuberculosis infection or tuberculosis disease were included, 261 in Phase 1 and 98 in Phase 2. In phase 2, a new nurse-led intervention was implemented in all patients and included two educational steps (written information in the child's native language and follow-up telephone calls) and two monitoring steps (Eidus-Hamilton test and follow-up questionnaire) that were exclusively carried out by nurses. Adherence to antituberculosis treatment increased from 74.7% in Phase 1 to 87.8% in Phase 2 (p=0.014; Chi-square test), after the implementation of the nurse-led intervention. In Phase 2, non-adherence was only associated with being born abroad (28.6% versus 7.8%; p=0.019; Chi-square test) and with foreign origin families (27.3% versus 0%; p<0.0001; Chi-square test). The nurse-led intervention was associated to an increase in adherence to antituberculosis treatment. Immigrant-related variables remained major risk factors for sub-optimal adherence in a low-endemic setting. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

VEMAP phase 2 bioclimatic database. I. Gridded historical (20th century) climate for modeling ecosystem dynamics across the conterminous USA

Treesearch

Timothy G.F. Kittel; Nan. A. Rosenbloom; J.A. Royle; C. Daly; W.P. Gibson; H.H. Fisher; P. Thornton; D.N. Yates; S. Aulenbach; C. Kaufman; R. McKeown; Dominque Bachelet; David S. Schimel

2004-01-01

Analysis and simulation of biospheric responses to historical forcing require surface climate data that capture those aspects of climate that control ecological processes, including key spatial gradients and modes of temporal variability. We developed a multivariate, gridded historical climate dataset for the conterminous USA as a common input database for the...

Stable and metastable nanowires displaying locally controllable properties

DOEpatents

Sutter, Eli Anguelova; Sutter, Peter Werner

2014-11-18

Vapor-liquid-solid growth of nanowires is tailored to achieve complex one-dimensional material geometries using phase diagrams determined for nanoscale materials. Segmented one-dimensional nanowires having constant composition display locally variable electronic band structures that are determined by the diameter of the nanowires. The unique electrical and optical properties of the segmented nanowires are exploited to form electronic and optoelectronic devices. Using gold-germanium as a model system, in situ transmission electron microscopy establishes, for nanometer-sized Au--Ge alloy drops at the tips of Ge nanowires (NWs), the parts of the phase diagram that determine their temperature-dependent equilibrium composition. The nanoscale phase diagram is then used to determine the exchange of material between the NW and the drop. The phase diagram for the nanoscale drop deviates significantly from that of the bulk alloy.

Vocal Acoustic and Auditory-Perceptual Characteristics During Fluctuations in Estradiol Levels During the Menstrual Cycle: A Longitudinal Study.

PubMed

Arruda, Polyanna; Diniz da Rosa, Marine Raquel; Almeida, Larissa Nadjara Alves; de Araujo Pernambuco, Leandro; Almeida, Anna Alice

2018-03-07

Estradiol production varies cyclically, changes in levels are hypothesized to affect the voice. The main objective of this study was to investigate vocal acoustic and auditory-perceptual characteristics during fluctuations in the levels of the hormone estradiol during the menstrual cycle. A total of 44 volunteers aged between 18 and 45 were selected. Of these, 27 women with regular menstrual cycles comprised the test group (TG) and 17 combined oral contraceptive users comprised the control group (CG). The study was performed in two phases. In phase 1, anamnesis was performed. Subsequently, the TG underwent blood sample collection for measurement of estradiol levels and voice recording for later acoustic and auditory-perceptual analysis. The CG underwent only voice recording. Phase 2 involved the same measurements as phase 1 for each group. Variables were evaluated using descriptive and inferential analysis to compare groups and phases and to determine relationships between variables. Voice changes were found during the menstrual cycle, and such changes were determined to be related to variations in estradiol levels. Impaired voice quality was observed to be associated with decreased levels of estradiol. The CG did not demonstrate significant vocal changes during phases 1 and 2. The TG showed significant increases in vocal parameters of roughness, tension, and instability during phase 2 (the period of low estradiol levels) when compared with the CG. Low estradiol levels were also found to be negatively correlated with the parameters of tension, instability, and jitter and positively correlated with fundamental voice frequency. Copyright © 2018 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Hypothyroidism impairs somatovisceral reflexes involved in micturition of female rabbits.

PubMed

Sánchez-García, Octavio; López-Juárez, Rhode; Rodríguez-Castelán, Julia; Corona-Quintanilla, Dora L; Martínez-Gómez, Margarita; Cuevas-Romero, Estela; Castelán, Francisco

2018-04-17

To determine the impact of hypothyroidism on the bladder and urethral functions as well as in the activation of the pubococcygeous (Pcm) and bulbospongiosus (Bsm) during micturition. Age-matched control and methimazole-induced hypothyroid female rabbits were used to simultaneously record cystometrograms, urethral pressure, and the reflex activation of Pcm and Bsm during the induced micturition. Urodynamic and urethral variables were measured. Activation or no activation of the Pcm and Bsm during the storage and voiding phases of micturition were categorized as 1 or 0. Significant differences (P ≤ 0.05) between control and hypothyroid groups were determined with unpaired Student-t or Mann-Whitney tests. One-month induced hypothyroidism increased the residual volume and threshold pressure while the opposite was true for the voided volume, maximal pressure, and voiding efficiency. Urethral pressure was also affected as supported by a notorious augmentation of the urethral resistance, among other changes in the rest of measured variables. Hypothyroidism also affected the reflex activation of the Pcm in the voiding phase of micturition. Our findings demonstrate hypothyroidism impairs the bladder and, urethral functions, and reflex activation of Pcm and Bsm affecting the micturition in female rabbits. © 2018 Wiley Periodicals, Inc.

Trunk lean gait decreases multi-segmental coordination in the vertical direction.

PubMed

Tokuda, Kazuki; Anan, Masaya; Sawada, Tomonori; Tanimoto, Kenji; Takeda, Takuya; Ogata, Yuta; Takahashi, Makoto; Kito, Nobuhiro; Shinkoda, Koichi

2017-11-01

[Purpose] The strategy of trunk lean gait to reduce external knee adduction moment (KAM) may affect multi-segmental synergy control of center of mass (COM) displacement. Uncontrolled manifold (UCM) analysis is an evaluation index to understand motor variability. The purpose of this study was to investigate how motor variability is affected by using UCM analysis on adjustment of the trunk lean angle. [Subjects and Methods] Fifteen healthy young adults walked at their preferred speed under two conditions: normal and trunk lean gait. UCM analysis was performed with respect to the COM displacement during the stance phase. The KAM data were analyzed at the points of the first KAM peak during the stance phase. [Results] The KAM during trunk lean gait was smaller than during normal gait. Despite a greater segmental configuration variance with respect to mediolateral COM displacement during trunk lean gait, the synergy index was not significantly different between the two conditions. The synergy index with respect to vertical COM displacement during trunk lean gait was smaller than that during normal gait. [Conclusion] These results suggest that trunk lean gait is effective in reducing KAM; however, it may decrease multi-segmental movement coordination of COM control in the vertical direction.

Invited Article: Generation of one-million-mode continuous-variable cluster state by unlimited time-domain multiplexing

NASA Astrophysics Data System (ADS)

Yoshikawa, Jun-ichi; Yokoyama, Shota; Kaji, Toshiyuki; Sornphiphatphong, Chanond; Shiozawa, Yu; Makino, Kenzo; Furusawa, Akira

2016-09-01

In recent quantum optical continuous-variable experiments, the number of fully inseparable light modes has drastically increased by introducing a multiplexing scheme either in the time domain or in the frequency domain. Here, modifying the time-domain multiplexing experiment reported in the work of Yokoyama et al. [Nat. Photonics 7, 982 (2013)], we demonstrate the successive generation of fully inseparable light modes for more than one million modes. The resulting multi-mode state is useful as a dual-rail continuous variable cluster state. We circumvent the previous problem of optical phase drifts, which has limited the number of fully inseparable light modes to around ten thousands, by continuous feedback control of the optical system.

Information fusion based optimal control for large civil aircraft system.

PubMed

Zhen, Ziyang; Jiang, Ju; Wang, Xinhua; Gao, Chen

2015-03-01

Wind disturbance has a great influence on landing security of Large Civil Aircraft. Through simulation research and engineering experience, it can be found that PID control is not good enough to solve the problem of restraining the wind disturbance. This paper focuses on anti-wind attitude control for Large Civil Aircraft in landing phase. In order to improve the riding comfort and the flight security, an information fusion based optimal control strategy is presented to restrain the wind in landing phase for maintaining attitudes and airspeed. Data of Boeing707 is used to establish a nonlinear mode with total variables of Large Civil Aircraft, and then two linear models are obtained which are divided into longitudinal and lateral equations. Based on engineering experience, the longitudinal channel adopts PID control and C inner control to keep longitudinal attitude constant, and applies autothrottle system for keeping airspeed constant, while an information fusion based optimal regulator in the lateral control channel is designed to achieve lateral attitude holding. According to information fusion estimation, by fusing hard constraint information of system dynamic equations and the soft constraint information of performance index function, optimal estimation of the control sequence is derived. Based on this, an information fusion state regulator is deduced for discrete time linear system with disturbance. The simulation results of nonlinear model of aircraft indicate that the information fusion optimal control is better than traditional PID control, LQR control and LQR control with integral action, in anti-wind disturbance performance in the landing phase. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Western Wind and Solar Integration Study Phase 2 (Presentation)

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

Lew, D.; Brinkman, G.; Ibanez, E.

This presentation accompanies Phase 2 of the Western Wind and Solar Integration Study, a follow-on to Phase 1, which examined the operational impacts of high penetrations of variable renewable generation on the electric power system in the West and was one of the largest variable generation studies to date. High penetrations of variable generation can induce cycling of fossil-fueled generators. Cycling leads to wear-and-tear costs and changes in emissions. Phase 2 calculated these costs and emissions, and simulated grid operations for a year to investigate the detailed impact of variable generation on the fossil-fueled fleet. The presentation highlights the scopemore » of the study and results.« less

Metacognitive Influences on Study Time Allocation in an Associative Recognition Task: An Analysis of Adult Age Differences

PubMed Central

Hines, Jarrod C.; Touron, Dayna R.; Hertzog, Christopher

2009-01-01

The current study evaluated a metacognitive account of study time allocation, which argues that metacognitive monitoring of recognition test accuracy and latency influences subsequent strategic control and regulation. We examined judgments of learning (JOLs), recognition test confidence judgments (CJs), and subjective response time (RT) judgments by younger and older adults in an associative recognition task involving two study-test phases, with self-paced study in phase 2. Multilevel regression analyses assessed the degree to which age and metacognitive variables predicted phase 2 study time independent of actual test accuracy and RT. Outcomes supported the metacognitive account – JOLs and CJs predicted study time independent of recognition accuracy. For older adults with errant RT judgments, subjective retrieval fluency influenced response confidence as well as (mediated through confidence) subsequent study time allocation. Older adults studied items longer which had been assigned lower CJs, suggesting no age deficit in using memory monitoring to control learning. PMID:19485662

Longitudinal study of microvascular involvement by nailfold capillaroscopy in children with Henoch-Schönlein purpura.

PubMed

Zampetti, Anna; Rigante, Donato; Bersani, Giulia; Rendeli, Claudia; Feliciani, Claudio; Stabile, Achille

2009-09-01

The aim of this study is to describe by video-nailfold capillaroscopy the microvascular involvement and capillary changes in children with Henoch-Schönlein purpura (HSp) and to establish a possible correlation with clinical outcome. Thirty-one patients underwent capillaroscopic evaluation through a videomicroscope during the acute phase and after 6 months. Twenty sex/age-matched controls were also examined. All capillaroscopic variables were statistically examined in combination with laboratoristic/clinical data. Architectural and morphological changes recorded during the acute phase were statistically significant in comparison to the controls (p < 0.01). At the follow-up, oedema was still observed in all patients, whereas, morphological changes only in two. There was a no significant correlation between capillaroscopy changes, laboratoristic/clinical data, and outcome. Video-nailfold capillaroscopy can be a simple tool to evaluate microvascular abnormalities in the acute phase of HSp, and the persistence of oedema could suggest an incomplete disease resolution at a microvascular level.

Pattern formation in mass conserving reaction-diffusion systems

NASA Astrophysics Data System (ADS)

Brauns, Fridtjof; Halatek, Jacob; Frey, Erwin

We present a rigorous theoretical framework able to generalize and unify pattern formation for quantitative mass conserving reaction-diffusion models. Mass redistribution controls chemical equilibria locally. Separation of diffusive mass redistribution on the level of conserved species provides a general mathematical procedure to decompose complex reaction-diffusion systems into effectively independent functional units, and to reveal the general underlying bifurcation scenarios. We apply this framework to Min protein pattern formation and identify the mechanistic roles of both involved protein species. MinD generates polarity through phase separation, whereas MinE takes the role of a control variable regulating the existence of MinD phases. Hence, polarization and not oscillations is the generic core dynamics of Min proteins in vivo. This establishes an intrinsic mechanistic link between the Min system and a broad class of intracellular pattern forming systems based on bistability and phase separation (wave-pinning). Oscillations are facilitated by MinE redistribution and can be understood mechanistically as relaxation oscillations of the polarization direction.

Phase transformations during the growth of paracetamol crystals from the vapor phase

NASA Astrophysics Data System (ADS)

Belyaev, A. P.; Rubets, V. P.; Antipov, V. V.; Bordei, N. S.

2014-07-01

Phase transformations during the growth of paracetamol crystals from the vapor phase are studied by differential scanning calorimetry. It is found that the vapor-crystal phase transition is actually a superposition of two phase transitions: a first-order phase transition with variable density and a second-order phase transition with variable ordering. The latter, being a diffuse phase transition, results in the formation of a new, "pretransition," phase irreversibly spent in the course of the transition, which ends in the appearance of orthorhombic crystals. X-ray diffraction data and micrograph are presented.

Voltage Controller

NASA Technical Reports Server (NTRS)

1997-01-01

Power Efficiency Corporation, specifically formed to manufacture and develop products from NASA technology, has a license to a three-phase power factor controller originally developed by Frank Nola, an engineer at Marshall Space Flight Center. Power Efficiency and two major distributors, Performance Control and Edison Power Technologies, use the electronic control boards to assemble three different motor controllers: Power Commander, Performance Controller, and Energy Master. The company Power Factor Controller reduces excessive energy waste in AC induction motors. It is used in industries and applications where motors operate under variable loads, including elevators and escalators, machine tools, intake and exhaust fans, oil wells, conveyors, pumps, die casting, and compressors. Customer lists include companies such as May Department Stores, Caesars Atlantic City, Ford Motors, and American Axle.

Vibration control of an energy regenerative seat suspension with variable external resistance

NASA Astrophysics Data System (ADS)

Ning, Donghong; Sun, Shuaishuai; Du, Haiping; Li, Weihua; Zhang, Nong

2018-06-01

In this paper, an energy regenerative seat suspension with a variable external resistance is proposed and built, and a semi-active controller for its vibration control is also designed and validated. The energy regenerative seat suspension is built with a three-phase generator and a gear reducer, which are installed in the scissors structure centre of the seat suspension, and the vibration energy is directly harvested from the rotary movement of suspension's scissors structure. The electromagnetic torque of the semi-active seat suspension actuator is controlled by an external variable resistor. An integrated model including the seat suspension's kinematics and the generator is built and proven to match the test result very well. A simplified experimental phenomenon model is also built based on the test results for the controller design. A state feedback H∞ controller is proposed for the regenerative seat suspension's semi-active vibration control. The proposed regenerative seat suspension and its controller are validated with both simulations and experiments. A well-tuned passive seat suspension is applied to evaluate the regenerative seat's performance. Based on ISO 2631-1, the frequency-weighted root mean square (FW-RMS) acceleration of the proposed seat suspension has a 22.84% reduction when compared with the passive one, which indicates the improvement of ride comfort. At the same time, the generated RMS power is 1.21 W. The proposed regenerative seat suspension can greatly improve the driver's ride comfort and has the potential to be developed to a self-powered semi-active system.

A fault-tolerant strategy based on SMC for current-controlled converters

NASA Astrophysics Data System (ADS)

Azer, Peter M.; Marei, Mostafa I.; Sattar, Ahmed A.

2018-05-01

The sliding mode control (SMC) is used to control variable structure systems such as power electronics converters. This paper presents a fault-tolerant strategy based on the SMC for current-controlled AC-DC converters. The proposed SMC is based on three sliding surfaces for the three legs of the AC-DC converter. Two sliding surfaces are assigned to control the phase currents since the input three-phase currents are balanced. Hence, the third sliding surface is considered as an extra degree of freedom which is utilised to control the neutral voltage. This action is utilised to enhance the performance of the converter during open-switch faults. The proposed fault-tolerant strategy is based on allocating the sliding surface of the faulty leg to control the neutral voltage. Consequently, the current waveform is improved. The behaviour of the current-controlled converter during different types of open-switch faults is analysed. Double switch faults include three cases: two upper switch fault; upper and lower switch fault at different legs; and two switches of the same leg. The dynamic performance of the proposed system is evaluated during healthy and open-switch fault operations. Simulation results exhibit the various merits of the proposed SMC-based fault-tolerant strategy.

Period variability of coupled noisy oscillators

NASA Astrophysics Data System (ADS)

Mori, Fumito; Kori, Hiroshi

2013-03-01

Period variability, quantified by the standard deviation (SD) of the cycle-to-cycle period, is investigated for noisy phase oscillators. We define the checkpoint phase as the beginning or end point of one oscillation cycle and derive an expression for the SD as a function of this phase. We find that the SD is dependent on the checkpoint phase only when oscillators are coupled. The applicability of our theory is verified using a realistic model. Our work clarifies the relationship between period variability and synchronization from which valuable information regarding coupling can be inferred.

Clustering of haemostatic variables and the effect of high cashew and walnut diets on these variables in metabolic syndrome patients.

PubMed

Pieters, Marlien; Oosthuizen, Welma; Jerling, Johann C; Loots, Du Toit; Mukuddem-Petersen, Janine; Hanekom, Susanna M

2005-09-01

We investigated the effect of a high walnut and cashew diet on haemostatic variables in people with the metabolic syndrome. Factor analysis was used to determine how the haemostatic variables cluster with other components of the metabolic syndrome and multiple regression to determine possible predictors. This randomized, control, parallel, controlled-feeding trial included 68 subjects who complied with the Third National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol criteria. After a 3-week run-in following the control diet, subjects were divided into three groups receiving either walnuts or cashews (20 energy%) or a control diet for 8 weeks. The nut intervention had no significant effect on von Willebrand factor antigen, fibrinogen, factor VII coagulant activity, plasminogen activator inhibitor 1 activity, tissue plasminogen activator activity or thrombin activatable fibrinolysis inhibitor. Statistically, fibrinogen clustered with the body-mass-correlates and acute phase response factors, and factor VII coagulant activity clustered with high-density lipoprotein cholesterol (HDL-C). Tissue plasminogen activator activity, plasminogen activator inhibitor 1 activity and von Willebrand factor antigen clustered into a separate endothelial function factor. HDL-C and markers of obesity were the strongest predictors of the haemostatic variables. We conclude that high walnut and cashew diets did not influence haemostatic factors in this group of metabolic syndrome subjects. The HDL-C increase and weight loss may be the main focus of dietary intervention for the metabolic syndrome. Furthermore, diet composition may have only limited effects if weight loss is not achieved.

Anti-calculus activity of a toothpaste with microgranules.

PubMed

Chesters, R K; O'Mullane, D M; Finnerty, A; Huntington, E; Jones, P R

1998-09-01

The objective of the trial was to determine the efficacy of the proven anticalculus active system (zinc citrate trihydrate [ZCT] and triclosan), when the ZCT is delivered from microgranules incorporated in a silica-based toothpaste containing 1450 ppm F as sodium fluoride. A monadic, single-blind, two phase design clinical trial was used to compare the effect of the test and a negative control fluoridated toothpaste on the formation of supragingival calculus. Male and female calculus-forming volunteers, aged 18 or over, were recruited for the study following a 2-week screening phase. All subjects were given a scale and polish of their eight lower anterior teeth at the start of both the pre-test and test phases. Subjects were supplied with a silica-based 1450 F ppm fluoridated toothpaste with no anti-calculus active for use during an 8-week pre-test phase. Calculus was assessed at the end of the pre-test and test phases using the Volpe-Manhold index (VMI). Subjects were stratified according to their pre-test VMI score (8-10, 10.5-12, > 12) and gender and then allocated at random to test or negative control toothpaste groups. Subjects with < 8 mm of calculus were excluded from further participation. The outcome variable was the mean VMI score for the test and negative control groups. The test toothpaste caused a statistically significant 30% reduction in calculus compared with the control paste after a 13-week use. No adverse events were reported during the study. The incorporation of the ZCT in microgranules did not adversely affect the anticalculus activity of the new formulation.

Virtual reality exercise on a home-based phase III cardiac rehabilitation program, effect on executive function, quality of life and depression, anxiety and stress: a randomized controlled trial.

PubMed

Vieira, Ágata; Melo, Cristina; Machado, Jorge; Gabriel, Joaquim

2018-02-01

To analyse the effect of a six-month home-based phase III cardiac rehabilitation (CR) specific exercise program, performed in a virtual reality (Kinect) or conventional (booklet) environment, on executive function, quality of life and depression, anxiety and stress of subjects with coronary artery disease. A randomized controlled trial was conducted with subjects, who had completed phase II, randomly assigned to intervention group 1 (IG1), whose program encompassed the use of Kinect (n = 11); or intervention group 2 (IG2), a paper booklet (n = 11); or a control group (CG), only subjected to the usual care (n = 11). The three groups received education on cardiovascular risk factors. The assessed parameters, at baseline (M0), 3 (M1) and 6 months (M2), were executive function, control and integration in the implementation of an adequate behaviour in relation to a certain objective, specifically the ability to switch information (Trail Making Test), working memory (Verbal Digit Span test), and selective attention and conflict resolution ability (Stroop test), quality of life (MacNew questionnaire) and depression, anxiety and stress (Depression, Anxiety and Stress Scale 21). Descriptive and inferential statistical measures were used, significance level was set at .05. The IG1 revealed significant improvements, in the selective attention and conflict resolution ability, in comparison with the CG in the variable difference M0 - M2 (p = .021) and in comparison with the IG2 in the variable difference M1 - M2 and M0 - M2 (p = .001 and p = .002, respectively). No significant differences were found in the quality of life, and depression, anxiety and stress. The virtual reality format had improved selective attention and conflict resolution ability, revealing the potential of CR, specifically with virtual reality exercise, on executive function. Implications for Rehabilitation In cardiac rehabilitation, especially in phase III, it is important to develop and to present alternative strategies, as virtual reality using the Kinect in a home context. Taking into account the relationship between the improvement of the executive function with physical exercise, it is relevant to access the impact of a cardiac rehabilitation program on the executive function. Enhancing the value of the phase III of cardiac rehabilitation.

VizieR Online Data Catalog: uvby photometry of 4 CP stars (Adelman, 1997)

NASA Astrophysics Data System (ADS)

Adelman, S. J.

1996-07-01

Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope refine the rotational periods and define the shapes of the light curves of four magnetic Chemically Peculiar stars. HD 32633 (P=6.43000d) exhibits an in-phase variability with asymmetrically shaped light curves. 25 Sex (P=4.37900d) has a complex variability with the v, b, and y light variability crudely in phase, but quite different from that of u. HR 7224 (P=1.123095d) shows in-phase variability with two nearly equal secondary minima. HD 200311 (P=26.0042d), which was previous thought to be a long period variable, is found to be a modest photometric variable. (5 data files).

Coupling the Solar-Wind/IMF to the Ionosphere through the High Latitude Cusps

NASA Technical Reports Server (NTRS)

Maynard, Nelson C.

2003-01-01

Magnetic merging is a primary means for coupling energy from the solar wind into the magnetosphere-ionosphere system. The location and nature of the process remain as open questions. By correlating measurements form diverse locations and using large-scale MHD models to put the measurements in context, it is possible to constrain out interpretations of the global and meso-scale dynamics of magnetic merging. Recent evidence demonstrates that merging often occurs at high latitudes in the vicinity of the cusps. The location is in part controlled by the clock angle in the interplanetary magnetic field (IMF) Y-Z plane. In fact, B(sub Y) bifurcated the cusp relative to source regions. The newly opened field lines may couple to the ionosphere at MLT locations of as much as 3 hr away from local noon. On the other side of noon the cusp may be connected to merging sites in the opposite hemisphere. In face, the small convection cell is generally driven by opposite hemisphere merging. B(sub X) controls the timing of the interaction and merging sites in each hemisphere, which may respond to planar features in the IMF at different times. Correlation times are variable and are controlled by the dynamics of the tilt of the interplanetary electric field phase plane. The orientation of the phase plane may change significantly on time scales of tens of minutes. Merging is temporally variable and may be occurring at multiple sites simultaneously. Accelerated electrons from the merging process excite optical signatures at the foot of the newly opened field lines. All-sky photometer observations of 557.7 nm emissions in the cusp region provide a "television picture" of the merging process and may be used to infer the temporal and spatial variability of merging, tied to variations in the IMF.

Mechanosensing of stem bending and its interspecific variability in five neotropical rainforest species.

PubMed

Coutand, Catherine; Chevolot, Malia; Lacointe, André; Rowe, Nick; Scotti, Ivan

2010-02-01

In rain forests, sapling survival is highly dependent on the regulation of trunk slenderness (height/diameter ratio): shade-intolerant species have to grow in height as fast as possible to reach the canopy but also have to withstand mechanical loadings (wind and their own weight) to avoid buckling. Recent studies suggest that mechanosensing is essential to control tree dimensions and stability-related morphogenesis. Differences in species slenderness have been observed among rainforest trees; the present study thus investigates whether species with different slenderness and growth habits exhibit differences in mechanosensitivity. Recent studies have led to a model of mechanosensing (sum-of-strains model) that predicts a quantitative relationship between the applied sum of longitudinal strains and the plant's responses in the case of a single bending. Saplings of five different neotropical species (Eperua falcata, E. grandiflora, Tachigali melinonii, Symphonia globulifera and Bauhinia guianensis) were subjected to a regimen of controlled mechanical loading phases (bending) alternating with still phases over a period of 2 months. Mechanical loading was controlled in terms of strains and the five species were subjected to the same range of sum of strains. The application of the sum-of-strain model led to a dose-response curve for each species. Dose-response curves were then compared between tested species. The model of mechanosensing (sum-of-strain model) applied in the case of multiple bending as long as the bending frequency was low. A comparison of dose-response curves for each species demonstrated differences in the stimulus threshold, suggesting two groups of responses among the species. Interestingly, the liana species B. guianensis exhibited a higher threshold than other Leguminosae species tested. This study provides a conceptual framework to study variability in plant mechanosensing and demonstrated interspecific variability in mechanosensing.

Abiotic variability among different aquatic systems of the central Amazon floodplain during drought and flood events.

PubMed

Affonso, A G; Queiroz, H L; Novo, E M L M

2015-11-01

This paper examines water properties from lakes, (depression lakes, sensu Junk et al., 2012), channels (scroll lakes with high connectivity, sensu Junk et al., 2012) and paleo-channels (scroll lakes with low connectivity-sensu Junk et al., 2012, locally called ressacas) located in Mamirauá Sustainable Development Reserve, in Central Amazon floodplain, Amazonas, Brazil. We analysed surface temperature, conductivity, pH, dissolved oxygen, turbidity, transparency, suspended inorganic and organic matter, chlorophyll-a, pheophytin, total nitrogen, total phosphorus, organic and inorganic carbon in 2009 high water phase, 2009 and 2010 low water phases. Multivariate statistical analyses of 24 aquatic systems (6 ressacas, 12 lakes and 6 channels, 142 samples) were applied to the variables in order to: 1) quantify differences among aquatic system types; 2) assess how those differences are affected in the different phases of the hydrological year. First, we analysed the entire set of variables to test for differences among phases of the hydrological year and types of aquatic systems using a PERMANOVA two-way crossed design. The results showed that the all measured limnological variables are distinct regarding both factors: types of aquatic systems and hydrological phases. In general, the magnitude and amplitude of all variables were higher in the low water phase than in the high water phase, except for water transparency in all aquatic system's types. PERMANOVA showed that the differences between aquatic system's types and hydrological phases of all variables were highly significant for both main factors (type and phase) and for the type x phase interaction. Limnological patterns of Amazon floodplain aquatic systems are highly dynamic, dependent on the surrounding environment, flood pulse, main river input and system type. These patterns show how undisturbed systems respond to natural variability in such a diverse environment, and how distinct are those aquatic systems, especially during the low water phase. Aquatic systems in Mamirauá floodplain represent limnological patterns of almost undisturbed areas and can be used as future reference for comparison with disturbed areas, such as those of the Lower Amazon, and as a baseline for studies on the effects of anthropogenic influences and climate change and on Amazon aquatic ecosystem.

Soil moisture dynamics and their effect on bioretention performance in Northeast Ohio

NASA Astrophysics Data System (ADS)

Bush, S. A.; Jefferson, A.; Jarden, K.; Kinsman-Costello, L. E.; Grieser, J.

2014-12-01

Urban impervious surfaces lead to increases in stormwater runoff. Green infrastructure, like bioretention cells, is being used to mitigate negative impacts of runoff by disconnecting impervious surfaces from storm water systems and redirecting flow to decentralized treatment areas. While bioretention soil characteristics are carefully designed, little research is available on soil moisture dynamics within the cells and how these might relate to inter-storm variability in performance. Bioretentions have been installed along a residential street in Parma, Ohio to determine the impact of green infrastructure on the West Creek watershed, a 36 km2 subwatershed of the Cuyahoga River. Bioretentions were installed in two phases (Phase I in 2013 and Phase II in 2014); design and vegetation density vary slightly between the two phases. Our research focuses on characterizing soil moisture dynamics of multiple bioretentions and assessing their impact on stormwater runoff at the street scale. Soil moisture measurements were collected in transects for eight bioretentions over the course of one summer. Vegetation indices of canopy height, percent vegetative cover, species richness and NDVI were also measured. A flow meter in the storm drain at the end of the street measured storm sewer discharge. Precipitation was recorded from a meteorological station 2 km from the research site. Soil moisture increased in response to precipitation and decreased to relatively stable conditions within 3 days following a rain event. Phase II bioretentions exhibited greater soil moisture and less vegetation than Phase I bioretentions, though the relationship between soil moisture and vegetative cover is inconclusive for bioretentions constructed in the same phase. Data from five storms suggest that pre-event soil moisture does not control the runoff-to-rainfall ratio, which we use as a measure of bioretention performance. However, discharge data indicate that hydrograph characteristics, such as lag time and peak flow, are altered relative to a control street. This analysis suggests that street-scale implementation of bioretention can reduce the impact of impervious surface on stormflows, but more information is needed to fully understand how soil moisture of the bioretentions affects inter-storm variability in performance.

Application of variable structure system theory to aircraft flight control. [AV-8A and the Augmentor Wing Jet STOL Research Aircraft

NASA Technical Reports Server (NTRS)

Calise, A. J.; Kadushin, I.; Kramer, F.

1981-01-01

The current status of research on the application of variable structure system (VSS) theory to design aircraft flight control systems is summarized. Two aircraft types are currently being investigated: the Augmentor Wing Jet STOL Research Aircraft (AWJSRA), and AV-8A Harrier. The AWJSRA design considers automatic control of longitudinal dynamics during the landing phase. The main task for the AWJSRA is to design an automatic landing system that captures and tracks a localizer beam. The control task for the AV-8A is to track velocity commands in a hovering flight configuration. Much effort was devoted to developing computer programs that are needed to carry out VSS design in a multivariable frame work, and in becoming familiar with the dynamics and control problems associated with the aircraft types under investigation. Numerous VSS design schemes were explored, particularly for the AWJSRA. The approaches that appear best suited for these aircraft types are presented. Examples are given of the numerical results currently being generated.

Interdecadal Change of Tropical Cyclone Genesis Controlling Parameter in Western North Pacific

NASA Astrophysics Data System (ADS)

Li, T.

2017-12-01

The main environmental parameter controlling tropical cyclone (TC) genesis in the western North Pacific (WNP) changed in different interdecadal periods. The interannual variability of TC genesis frequency was primarily control by specific humidity in 1950-1976, sea surface temperature (SST) in 1977-1998, and vorticity in 1999-2014. A further diagnosis shows that the change of environmental specific humidity during 1950-1976 was attributed to anomalous advection of mean moisture during ENSO developing summer. The SST change during 1977-1998 was associated with circulation change during ENSO decaying summer. The change of environment vorticity was primarily related to CP-type El Niño during 1999-2014. The ultimate cause of the controlling parameter change is attributed to the change of ENSO behavior. Compared to the first period, a stronger EP-type ENSO variability in the second period leads to a stronger circulation/SST response during ENSO decaying phase. The occurrence of more frequent CP type El Niño in the third period was responsible for greater vorticity controlling in the WNP.

Effects of assisted and variable mechanical ventilation on cardiorespiratory interactions in anesthetized pigs.

PubMed

Beda, Alessandro; Güldner, Andreas; Simpson, David M; Carvalho, Nadja C; Franke, Susanne; Uhlig, Christopher; Koch, Thea; Pelosi, Paolo; de Abreu, Marcelo Gama

2012-03-01

The physiological importance of respiratory sinus arrhythmia (RSA) and cardioventilatory coupling (CVC) has not yet been fully elucidated, but these phenomena might contribute to improve ventilation/perfusion matching, with beneficial effects on gas exchange. Furthermore, decreased RSA amplitude has been suggested as an indicator of impaired autonomic control and poor clinical outcome, also during positive-pressure mechanical ventilation (MV). However, it is currently unknown how different modes of MV, including variable tidal volumes (V(T)), affect RSA and CVC during anesthesia. We compared the effects of pressure controlled (PCV) versus pressure assisted (PSV) ventilation, and of random variable versus constant V(T), on RSA and CVC in eight anesthetized pigs. At comparable depth of anesthesia, global hemodynamics, and ventilation, RSA amplitude increased from 20 ms in PCV to 50 ms in PSV (p < 0.05). CVC was detected (using proportional Shannon entropy of the interval between each inspiration onset and the previous R-peak in ECG) in two animals in PCV and seven animals in PSV. Variable V(T) did not significantly influence these phenomena. Furthermore, heart period and systolic arterial pressure oscillations were in phase during PCV but in counter-phase during PSV. At the same depth of anesthesia in pigs, PSV increases RSA amplitude and CVC compared to PCV. Our data suggest that the central respiratory drive, but not the baroreflex or the mechano-electric feedback in the heart, is the main mechanism behind the RSA increase. Hence, differences in RSA and CVC between mechanically ventilated patients might reflect the difference in ventilation mode rather than autonomic impairment. Also, since gas exchange did not increase from PCV to PSV, it is questionable whether RSA has any significance in improving ventilation/perfusion matching during MV.

Generalized Autobalanced Ramsey Spectroscopy of Clock Transitions

NASA Astrophysics Data System (ADS)

Yudin, V. I.; Taichenachev, A. V.; Basalaev, M. Yu.; Zanon-Willette, T.; Pollock, J. W.; Shuker, M.; Donley, E. A.; Kitching, J.

2018-05-01

When performing precision measurements, the quantity being measured is often perturbed by the measurement process itself. Such measurements include precision frequency measurements for atomic clock applications carried out with Ramsey spectroscopy. With the aim of eliminating probe-induced perturbations, a method of generalized autobalanced Ramsey spectroscopy (GABRS) is presented and rigorously substantiated. The usual local-oscillator frequency control loop is augmented with a second control loop derived from secondary Ramsey sequences interspersed with the primary sequences and with a different Ramsey period. This second loop feeds back to a secondary clock variable and ultimately compensates for the perturbation of the clock frequency caused by the measurements in the first loop. We show that such a two-loop scheme can lead to perfect compensation for measurement-induced light shifts and does not suffer from the effects of relaxation, time-dependent pulse fluctuations and phase-jump modulation errors that are typical of other hyper-Ramsey schemes. Several variants of GABRS are explored based on different secondary variables including added relative phase shifts between Ramsey pulses, external frequency-step compensation, and variable second-pulse duration. We demonstrate that a universal antisymmetric error signal, and hence perfect compensation at a finite modulation amplitude, is generated only if an additional frequency step applied during both Ramsey pulses is used as the concomitant variable parameter. This universal technique can be applied to the fields of atomic clocks, high-resolution molecular spectroscopy, magnetically induced and two-photon probing schemes, Ramsey-type mass spectrometry, and the field of precision measurements. Some variants of GABRS can also be applied for rf atomic clocks using coherent-population-trapping-based Ramsey spectroscopy of the two-photon dark resonance.

Bioprocess development workflow: Transferable physiological knowledge instead of technological correlations.

PubMed

Reichelt, Wieland N; Haas, Florian; Sagmeister, Patrick; Herwig, Christoph

2017-01-01

Microbial bioprocesses need to be designed to be transferable from lab scale to production scale as well as between setups. Although substantial effort is invested to control technological parameters, usually the only true constant parameter is the actual producer of the product: the cell. Hence, instead of solely controlling technological process parameters, the focus should be increasingly laid on physiological parameters. This contribution aims at illustrating a workflow of data life cycle management with special focus on physiology. Information processing condenses the data into physiological variables, while information mining condenses the variables further into physiological descriptors. This basis facilitates data analysis for a physiological explanation for observed phenomena in productivity. Targeting transferability, we demonstrate this workflow using an industrially relevant Escherichia coli process for recombinant protein production and substantiate the following three points: (1) The postinduction phase is independent in terms of productivity and physiology from the preinduction variables specific growth rate and biomass at induction. (2) The specific substrate uptake rate during induction phase was found to significantly impact the maximum specific product titer. (3) The time point of maximum specific titer can be predicted by an easy accessible physiological variable: while the maximum specific titers were reached at different time points (19.8 ± 7.6 h), those maxima were reached all within a very narrow window of cumulatively consumed substrate dSn (3.1 ± 0.3 g/g). Concluding, this contribution provides a workflow on how to gain a physiological view on the process and illustrates potential benefits. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:261-270, 2017. © 2016 American Institute of Chemical Engineers.

A controlled study of concurrent therapy with a nonacetylated salicylate and naproxen in rheumatoid arthritis.

PubMed

Furst, D E; Blocka, K; Cassell, S; Harris, E R; Hirschberg, J M; Josephson, N; Lachenbruch, P A; Trimble, R B; Paulus, H E

1987-02-01

Previous studies of combinations of nonsteroidal drugs used in the treatment of rheumatoid arthritis (RA) have yielded conflicting results. We used standard methods to measure disease activity and high pressure liquid chromatography to measure plasma drug concentrations. We used doses of choline magnesium trisalicylate, adjusted to achieve therapeutic serum salicylate concentrations, and naproxen in a randomized, double-blind, placebo-controlled cross-over study of full dose trisalicylate (CMT), full dose naproxen (N), full dose of both (CMT-N), and half dose of both (cmt-n) to examine their relative efficacy and toxicity in treating RA. CMT-N was statistically superior to all other treatments in only 1 of 12 efficacy variables, but was equal to N and better than CMT or cmt-n for 7 variables. There were minimal differences among treatments for the other 4 efficacy variables. The mean percentage difference for the efficacy variables between CMT-N and N was 3%, between CMT-N and CMT was 10.6%, and between CMT-N and cmt-n was 10.5%. Thirteen percent of patients manifested toxic reactions during the initial open dose-adjustment salicylate run-in phase. During the double-blind phases of the study, CMT-N was more toxic than N, CMT, or cmt-n (7.5% versus 3.4%, 1.8%, and 3.7%, respectively). Tinnitus was more common when full-dose CMT was used; N (N or CMT-N) was associated with increased skin toxicity. Gastrointestinal complaints were equally common with all regimens. CMT-N, although sometimes statistically superior to CMT, N, or cmt-n, showed no clinically important additive or synergistic effect versus N or CMT alone.

Ocean impact on decadal Atlantic climate variability revealed by sea-level observations.

PubMed

McCarthy, Gerard D; Haigh, Ivan D; Hirschi, Joël J-M; Grist, Jeremy P; Smeed, David A

2015-05-28

Decadal variability is a notable feature of the Atlantic Ocean and the climate of the regions it influences. Prominently, this is manifested in the Atlantic Multidecadal Oscillation (AMO) in sea surface temperatures. Positive (negative) phases of the AMO coincide with warmer (colder) North Atlantic sea surface temperatures. The AMO is linked with decadal climate fluctuations, such as Indian and Sahel rainfall, European summer precipitation, Atlantic hurricanes and variations in global temperatures. It is widely believed that ocean circulation drives the phase changes of the AMO by controlling ocean heat content. However, there are no direct observations of ocean circulation of sufficient length to support this, leading to questions about whether the AMO is controlled from another source. Here we provide observational evidence of the widely hypothesized link between ocean circulation and the AMO. We take a new approach, using sea level along the east coast of the United States to estimate ocean circulation on decadal timescales. We show that ocean circulation responds to the first mode of Atlantic atmospheric forcing, the North Atlantic Oscillation, through circulation changes between the subtropical and subpolar gyres--the intergyre region. These circulation changes affect the decadal evolution of North Atlantic heat content and, consequently, the phases of the AMO. The Atlantic overturning circulation is declining and the AMO is moving to a negative phase. This may offer a brief respite from the persistent rise of global temperatures, but in the coupled system we describe, there are compensating effects. In this case, the negative AMO is associated with a continued acceleration of sea-level rise along the northeast coast of the United States.

Effects of an emotional intelligence program in variables related to the prevention of violence

PubMed Central

Garaigordobil, Maite; Peña-Sarrionandia, Ainize

2015-01-01

In recent decades, numerous studies have shown a significant increase in violence during childhood and adolescence. These data suggest the importance of implementing programs to prevent and reduce violent behavior. The study aimed to design a program of emotional intelligence (EI) for adolescents and to assess its effects on variables related to violence prevention. The possible differential effect of the program on both genders was also examined. The sample comprised 148 adolescents aged from 13 to 16 years. The study used an experimental design with repeated pretest–posttest measures and control groups. To measure the variables, four assessment instruments were administered before and after the program, as well as in the follow-up phase (1 year after the conclusion of the intervention). The program consisted of 20 one-hour sessions. The pretest–posttest ANCOVAs showed that the program significantly increased: (1) EI (attention, clarity, emotional repair); (2) assertive cognitive social interaction strategies; (3) internal control of anger; and (4) the cognitive ability to analyze negative feelings. In the follow-up phase, the positive effects of the intervention were generally maintained and, moreover, the use of aggressive strategies as an interpersonal conflict-resolution technique was significantly reduced. Regarding the effect of the program on both genders, the change was very similar, but the boys increased assertive social interaction strategies, attention, and emotional clarity significantly more than the girls. The importance of implementing programs to promote socio-emotional development and prevent violence is discussed. PMID:26082743

Effects of an emotional intelligence program in variables related to the prevention of violence.

PubMed

Garaigordobil, Maite; Peña-Sarrionandia, Ainize

2015-01-01

In recent decades, numerous studies have shown a significant increase in violence during childhood and adolescence. These data suggest the importance of implementing programs to prevent and reduce violent behavior. The study aimed to design a program of emotional intelligence (EI) for adolescents and to assess its effects on variables related to violence prevention. The possible differential effect of the program on both genders was also examined. The sample comprised 148 adolescents aged from 13 to 16 years. The study used an experimental design with repeated pretest-posttest measures and control groups. To measure the variables, four assessment instruments were administered before and after the program, as well as in the follow-up phase (1 year after the conclusion of the intervention). The program consisted of 20 one-hour sessions. The pretest-posttest ANCOVAs showed that the program significantly increased: (1) EI (attention, clarity, emotional repair); (2) assertive cognitive social interaction strategies; (3) internal control of anger; and (4) the cognitive ability to analyze negative feelings. In the follow-up phase, the positive effects of the intervention were generally maintained and, moreover, the use of aggressive strategies as an interpersonal conflict-resolution technique was significantly reduced. Regarding the effect of the program on both genders, the change was very similar, but the boys increased assertive social interaction strategies, attention, and emotional clarity significantly more than the girls. The importance of implementing programs to promote socio-emotional development and prevent violence is discussed.

Geochemical Modeling of Reactions and Partitioning of Trace Metals and Radionuclides during Titration of Contaminated Acidic Sediments

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

Zhang, Fan; Parker, Jack C.; Luo, Wensui

2008-01-01

Many geochemical reactions that control aqueous metal concentrations are directly affected by solution pH. However, changes in solution pH are strongly buffered by various aqueous phase and solid phase precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior of the soil-solution system is thus critical to predict metal transport under variable pH conditions. This study was undertaken to develop a practical generic geochemical modeling approach to predict aqueous and solid phase concentrations of metals and anions during conditions of acid or base additions. The method of Spalding and Spalding was utilized to model soil buffer capacity and pH-dependent cationmore » exchange capacity by treating aquifer solids as a polyprotic acid. To simulate the dynamic and pH-dependent anion exchange capacity, the aquifer solids were simultaneously treated as a polyprotic base controlled by mineral precipitation/dissolution reactions. An equilibrium reaction model that describes aqueous complexation, precipitation, sorption and soil buffering with pH-dependent ion exchange was developed using HydroGeoChem v5.0 (HGC5). Comparison of model results with experimental titration data of pH, Al, Ca, Mg, Sr, Mn, Ni, Co, and SO{sub 4}{sup 2-} for contaminated sediments indicated close agreement, suggesting that the model could potentially be used to predict the acid-base behavior of the sediment-solution system under variable pH conditions.« less

A Priori Subgrid Scale Modeling for a Droplet Laden Temporal Mixing Layer

NASA Technical Reports Server (NTRS)

Okongo, Nora; Bellan, Josette

2000-01-01

Subgrid analysis of a transitional temporal mixing layer with evaporating droplets has been performed using a direct numerical simulation (DNS) database. The DNS is for a Reynolds number (based on initial vorticity thickness) of 600, with droplet mass loading of 0.2. The gas phase is computed using a Eulerian formulation, with Lagrangian droplet tracking. Since Large Eddy Simulation (LES) of this flow requires the computation of unfiltered gas-phase variables at droplet locations from filtered gas-phase variables at the grid points, it is proposed to model these by assuming the gas-phase variables to be given by the filtered variables plus a correction based on the filtered standard deviation, which can be computed from the sub-grid scale (SGS) standard deviation. This model predicts unfiltered variables at droplet locations better than simply interpolating the filtered variables. Three methods are investigated for modeling the SGS standard deviation: Smagorinsky, gradient and scale-similarity. When properly calibrated, the gradient and scale-similarity methods give results in excellent agreement with the DNS.

Multivariable Hermite polynomials and phase-space dynamics

NASA Technical Reports Server (NTRS)

Dattoli, G.; Torre, Amalia; Lorenzutta, S.; Maino, G.; Chiccoli, C.

1994-01-01

The phase-space approach to classical and quantum systems demands for advanced analytical tools. Such an approach characterizes the evolution of a physical system through a set of variables, reducing to the canonically conjugate variables in the classical limit. It often happens that phase-space distributions can be written in terms of quadratic forms involving the above quoted variables. A significant analytical tool to treat these problems may come from the generalized many-variables Hermite polynomials, defined on quadratic forms in R(exp n). They form an orthonormal system in many dimensions and seem the natural tool to treat the harmonic oscillator dynamics in phase-space. In this contribution we discuss the properties of these polynomials and present some applications to physical problems.

Overview of the DARPA/AFRL/NASA Smart Wing Phase II program

NASA Astrophysics Data System (ADS)

Kudva, Jayanth N.; Sanders, Brian P.; Pinkerton-Florance, Jennifer L.; Garcia, Ephrahim

2001-06-01

The DARPA/AFRL/NASA Smart Wing program, conducted by a team led by Northrop Grumman Corporation (NGC) under the DARPA Smart Materials and Structures initiative, addresses the development of smart technologies and demonstration of relevant concepts to improve the aerodynamic performance of military aircraft. This paper presents an overview of the smart wing program. The program is divided into two phases. Under Phase 1, (1995 - 1999) the NGC team developed adaptive wing structures with integrated actuation mechanisms to replace standard hinged control surfaces and provide variable, optimal aerodynamic shapes for a variety of flight regimes. Two half-span 16% scale wind tunnel models, representative of an advanced military aircraft wing, one with conventional control surfaces and the other with shape memory alloy (SMA) actuated smart control surfaces, were fabricated and tested in the NASA Langley Research Center (LaRC) Transonic Dynamics Tunnel (TDT) wind tunnel during two series of tests, conducted in May 1996 and June 1998, respectively. Details of the Phase 1 effort are documented in several papers. The on-going Phase 2 effort discussed here was started in January 1997 and includes several significant improvements over Phase 1: 1) a much larger, full-span model; 2) both leading edge (LE) and trailing edge (TE) smart control surfaces; 3) high-band width actuation systems; and 4) wind tunnel tests at transonic Mach numbers and high dynamic pressures (up to 300 psf.) representative of operational flight regimes. Phase 2 includes two wind tunnel tests, both at the NASA LaRC TDT - the first one was completed in March 2000 and the second (and final) test is scheduled for April 2001. The first test-demonstrated roll-effectiveness over a wide range of Mach numbers achieved using a combination of hingeless, smoothly contoured, SMA actuated, LE and TE control surfaces. The second test addresses the development and demonstration of high bandwidth actuation. An overview of the Phase 2 effort is presented here; detailed discussions of the wind tunnel testing, model design and fabrication, and actuation system development are given in companion papers.

Biomechanical mechanism of lateral trunk lean gait for knee osteoarthritis patients.

PubMed

Tokuda, Kazuki; Anan, Masaya; Takahashi, Makoto; Sawada, Tomonori; Tanimoto, Kenji; Kito, Nobuhiro; Shinkoda, Koichi

2018-01-03

The biomechanical mechanism of lateral trunk lean gait employed to reduce external knee adduction moment (KAM) for knee osteoarthritis (OA) patients is not well known. This mechanism may relate to the center of mass (COM) motion. Moreover, lateral trunk lean gait may affect motor control of the COM displacement. Uncontrolled manifold (UCM) analysis is an evaluation index used to understand motor control and variability of the motor task. Here we aimed to clarify the biomechanical mechanism to reduce KAM during lateral trunk lean gait and how motor variability controls the COM displacement. Twenty knee OA patients walked under two conditions: normal and lateral trunk lean gait conditions. UCM analysis was performed with respect to the COM displacement in the frontal plane. We also determined how the variability is structured with regards to the COM displacement as a performance variable. The peak KAM under lateral trunk lean gait was lower than that under normal gait. The reduced peak KAM observed was accompanied by medially shifted knee joint center, shortened distance of the center of pressure to knee joint center, and shortened distance of the knee-ground reaction force lever arm during the stance phase. Knee OA patients with lateral trunk lean gait could maintain kinematic synergy by utilizing greater segmental configuration variance to the performance variable. However, the COM displacement variability of lateral trunk lean gait was larger than that of normal gait. Our findings may provide clinical insights to effectively evaluate and prescribe gait modification training for knee OA patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Status of NASA Rotorcraft Research

DTIC Science & Technology

2009-09-01

approximate threefold range in the values of CP. It has been found useful in many cases to include additional independent variables and group...and improved rotorcraft. These needs include better analysis and better data. Many plans proposed for NASA rotorcraft research are discussed here, to...a successful active noise- control system include : obtaining a clean reference signal with minimal phase jitter; achieving a global reduction of

A variable-mode stator consequent pole memory machine

NASA Astrophysics Data System (ADS)

Yang, Hui; Lyu, Shukang; Lin, Heyun; Zhu, Z. Q.

2018-05-01

In this paper, a variable-mode concept is proposed for the speed range extension of a stator-consequent-pole memory machine (SCPMM). An integrated permanent magnet (PM) and electrically excited control scheme is utilized to simplify the flux-weakening control instead of relatively complicated continuous PM magnetization control. Due to the nature of memory machine, the magnetization state of low coercive force (LCF) magnets can be easily changed by applying either a positive or negative current pulse. Therefore, the number of PM poles may be changed to satisfy the specific performance requirement under different speed ranges, i.e. the machine with all PM poles can offer high torque output while that with half PM poles provides wide constant power range. In addition, the SCPMM with non-magnetized PMs can be considered as a dual-three phase electrically excited reluctance machine, which can be fed by an open-winding based dual inverters that provide direct current (DC) bias excitation to further extend the speed range. The effectiveness of the proposed variable-mode operation for extending its operating region and improving the system reliability is verified by both finite element analysis (FEA) and experiments.

Screening of melon genotypes for resistance to vegetable leafminer and your phenotypic correlations with colorimetry.

PubMed

Oliveira, Frederico I C DE; Fiege, Leonardo B C; Celin, Elaine F; Innecco, Renato; Nunes, Glauber H S; Aragão, Fernando A S DE

2017-01-01

Melon is one of the most important vegetable crops in the world. With short cycle in a system of phased planting, phytosanitary control is compromised, and a great volume of agricultural chemicals is used to control vegetable leafminer. Genetic control is an ideal alternative to avoid the damage caused by this insect. Thus, the aim of this study was to evaluate Cucumis accessions in regard to resistance to leafminer and correlate the variables analyzed. Fifty-four accessions and four commercial hybrids of melon were tested. The study was divided into two experiments: with and with no choice. The following characteristics were evaluated: with choice, in field - subjective score based on the infestation and the number of mines per leaf; and with no choice, in cage - number of mines per leaf, chlorophyll content, and leaf colorimetry. The results showed variability among the accessions and some genotypes showed favorable results for resistance in both experiments. There was correlation between the two variables in the experiment in the field. The accessions CNPH 11-282, CNPH 06-1047, and CNPH 11-1077 are the most recommended for future breeding programs with aim on introgression of resistance to vegetable leafminer in melon.

Experimental investigation of high-incidence delta-wing flow control

NASA Astrophysics Data System (ADS)

Buzica, Andrei; Bartasevicius, Julius; Breitsamter, Christian

2017-09-01

The possibility of extending the flight envelope for configurations with slender delta-shaped wings is investigated in this study by means of active flow control through pulsating jets from slot pairs distributed along the leading edge. The experiments comprise stereoscopic particle image velocimetry as well as force and moment measurements on a half-delta wing model. The analysis focuses on three high-incidence regimes: pre-stall, stall, and post-stall. This study also compares different perturbation methods: blowing with spatially constant and variable parameters, frequency and phase. At an incidence of 45°, the unison pulsed blowing facilitates the most significant flow transformation. Here, the separated shear layer reattaches on the wing's suction side, thus increasing the lift. Phase-averaged flow field measurements describe, in this particular case, the underlying physics of the flow-disturbance interaction.

Application of mass spectrometry based electronic nose and chemometrics for fingerprinting radiation treatment

NASA Astrophysics Data System (ADS)

Gupta, Sumit; Variyar, Prasad S.; Sharma, Arun

2015-01-01

Volatile compounds were isolated from apples and grapes employing solid phase micro extraction (SPME) and subsequently analyzed by GC/MS equipped with a transfer line without stationary phase. Single peak obtained was integrated to obtain total mass spectrum of the volatile fraction of samples. A data matrix having relative abundance of all mass-to-charge ratios was subjected to principal component analysis (PCA) and linear discriminant analysis (LDA) to identify radiation treatment. PCA results suggested that there is sufficient variability between control and irradiated samples to build classification models based on supervised techniques. LDA successfully aided in segregating control from irradiated samples at all doses (0.1, 0.25, 0.5, 1.0, 1.5, 2.0 kGy). SPME-MS with chemometrics was successfully demonstrated as simple screening method for radiation treatment.

Factors controlling crystallization of miserite glass-ceramic.

PubMed

Muhammed, Fenik K; Moorehead, Robert; van Noort, Richard; Pollington, Sarah

2015-12-01

The purpose of this study was to investigate a range of variables affecting the synthesis of a miserite glass-ceramic (GC). Miserite glass was synthesized by the melt quench technique. The crystallization kinetics of the glass were determined using Differential Thermal Analysis (DTA). The glasses were ground with dry ball-milling and then sieved to different particle sizes prior to sintering. These particle sizes were submitted to heat treatment regimes in a high temperature furnace to form the GC. The crystal phases of the GC were analyzed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was used to examine the microstructure of the cerammed glass. XRD analysis confirmed that the predominant crystalline phase of the GC was miserite along with a minor crystalline phase of cristobalite only when the particle size is <20 μm and the heat treatment at 1000°C was carried out for 4h and slowly cooled at the furnace rate. For larger particle sizes and faster cooling rates, a pseudowollastonite crystalline phase was produced. Short sintering times produced either a pseudowollastonite or xonotolite crystalline phase. The current study has shown that particle size and heat treatment schedules are major factors in controlling the synthesis of miserite GC. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Optimal aeroassisted orbital transfer with plane change using collocation and nonlinear programming

NASA Technical Reports Server (NTRS)

Shi, Yun. Y.; Nelson, R. L.; Young, D. H.

1990-01-01

The fuel optimal control problem arising in the non-planar orbital transfer employing aeroassisted technology is addressed. The mission involves the transfer from high energy orbit (HEO) to low energy orbit (LEO) with orbital plane change. The basic strategy here is to employ a combination of propulsive maneuvers in space and aerodynamic maneuvers in the atmosphere. The basic sequence of events for the aeroassisted HEO to LEO transfer consists of three phases. In the first phase, the orbital transfer begins with a deorbit impulse at HEO which injects the vehicle into an elliptic transfer orbit with perigee inside the atmosphere. In the second phase, the vehicle is optimally controlled by lift and bank angle modulations to perform the desired orbital plane change and to satisfy heating constraints. Because of the energy loss during the turn, an impulse is required to initiate the third phase to boost the vehicle back to the desired LEO orbital altitude. The third impulse is then used to circularize the orbit at LEO. The problem is solved by a direct optimization technique which uses piecewise polynomial representation for the state and control variables and collocation to satisfy the differential equations. This technique converts the optimal control problem into a nonlinear programming problem which is solved numerically. Solutions were obtained for cases with and without heat constraints and for cases of different orbital inclination changes. The method appears to be more powerful and robust than other optimization methods. In addition, the method can handle complex dynamical constraints.

Formulation Optimization of Human Insulin Loaded Microspheres for Controlled Oral Delivery Using Response Surface Methodology.

PubMed

Agrawal, Gauravkuma; Wakte, Pravin; Shelke, Santosh

2017-01-01

The objectives of the present investigation were to prepare recombinant human insulin entrapped Eudragit-S100 microspheres containing protease inhibitors and to precisely analyze the outcome of different formulation variables on the microspheres properties using a response surface methodology to develop an optimized formulation with desirable features. A central composite design was employed to produce microspheres of therapeutic protein by w/o/w multiple emulsion solvent evaporation technique using Eudragit S-100 as coating material and polyvinyl alcohol as a stabilizer. The effect of formulation variables (independent variables) that is levels of Eudragit S-100 (X1), therapeutic protein (X2), volumes of inner aqueous phase (X3) and external aqueous phase (X4) on dependant variables, that are encapsulation efficiency (Y1), drug release at pH 1.2 after 2 h (Y2) and drug release at pH 7.4 after of 2 h (Y3) were evaluated. The significant terms in the mathematical models were generated for each response parameter using multiple linear regression analysis and analysis of variance. All the formulation variables except the volume of external aqueous phase (X4) exerted a significant effect (P <0.05) on drug encapsulation efficiency (Y1) whereas first two variables, namely the levels of Eudragit S-100 (X1) and therapeutic protein (X2) materialized as the determining factors which significantly influenced drug release at pH 1.2 after 2 h (Y2) and drug release at pH 7.4 after of 2 h (Y3). The formulation was numerically optimized by framing the constraints on the dependent and independent variables using the desirability approach. The experimental values for Y1 and Y2 of optimized formulation were found to be 77.65% and 3.64%, respectively which were quite closer to results suggested by software. The results recorded indicate that the recombinant human insulin loaded Eudragit S-100 microspheres containing aprotinin have the benefits of higher loading efficiency, pH responsive and prolonged release characteristics, which may help to carry insulin to the optimum site of absorption. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Elimination of spiral waves in a locally connected chaotic neural network by a dynamic phase space constraint.

PubMed

Li, Yang; Oku, Makito; He, Guoguang; Aihara, Kazuyuki

2017-04-01

In this study, a method is proposed that eliminates spiral waves in a locally connected chaotic neural network (CNN) under some simplified conditions, using a dynamic phase space constraint (DPSC) as a control method. In this method, a control signal is constructed from the feedback internal states of the neurons to detect phase singularities based on their amplitude reduction, before modulating a threshold value to truncate the refractory internal states of the neurons and terminate the spirals. Simulations showed that with appropriate parameter settings, the network was directed from a spiral wave state into either a plane wave (PW) state or a synchronized oscillation (SO) state, where the control vanished automatically and left the original CNN model unaltered. Each type of state had a characteristic oscillation frequency, where spiral wave states had the highest, and the intra-control dynamics was dominated by low-frequency components, thereby indicating slow adjustments to the state variables. In addition, the PW-inducing and SO-inducing control processes were distinct, where the former generally had longer durations but smaller average proportions of affected neurons in the network. Furthermore, variations in the control parameter allowed partial selectivity of the control results, which were accompanied by modulation of the control processes. The results of this study broaden the applicability of DPSC to chaos control and they may also facilitate the utilization of locally connected CNNs in memory retrieval and the exploration of traveling wave dynamics in biological neural networks. Copyright © 2017 Elsevier Ltd. All rights reserved.

Individuals with autism spectrum disorder show abnormalities during initial and subsequent phases of precision gripping

PubMed Central

Magnon, Grant C.; White, Stormi P.; Greene, Rachel K.; Vaillancourt, David E.

2014-01-01

Sensorimotor impairments are common in autism spectrum disorder (ASD), but they are not well understood. Here we examined force control during initial pulses and the subsequent rise, sustained, and relaxation phases of precision gripping in 34 individuals with ASD and 25 healthy control subjects. Participants pressed on opposing load cells with their thumb and index finger while receiving visual feedback regarding their performance. They completed 2- and 8-s trials during which they pressed at 15%, 45%, or 85% of their maximum force. Initial pulses guided by feedforward control mechanisms, sustained force output controlled by visual feedback processes, and force relaxation rates all were examined. Control subjects favored an initial pulse strategy characterized by a rapid increase in and then relaxation of force when the target force was low (Type 1). When the target force level or duration of trials was increased, control subjects transitioned to a strategy in which they more gradually increased their force, paused, and then increased their force again. Individuals with ASD showed a more persistent bias toward the Type 1 strategy at higher force levels and during longer trials, and their initial force output was less accurate than that of control subjects. Patients showed increased force variability compared with control subjects when attempting to sustain a constant force level. During the relaxation phase, they showed reduced rates of force decrease. These findings suggest that both feedforward and feedback motor control mechanisms are compromised in ASD and these deficits may contribute to the dyspraxia and sensorimotor abnormalities often seen in this disorder. PMID:25552638

Challenges in Characterizing and Controlling Complex Cellular Systems

NASA Astrophysics Data System (ADS)

Wikswo, John

2011-03-01

Multicellular dynamic biological processes such as developmental differentiation, wound repair, disease, aging, and even homeostasis can be represented by trajectories through a phase space whose extent reflects the genetic, post-translational, and metabolic complexity of the process - easily extending to tens of thousands of dimensions. Intra- and inter-cellular sensing and regulatory systems and their nested, redundant, and non-linear feed-forward and feed-back controls create high-dimensioned attractors in this phase space. Metabolism provides free energy to drive non-equilibrium processes and dynamically reconfigure attractors. Studies of single molecules and cells provide only minimalist projections onto a small number of axes. It may be difficult to infer larger-scale emergent behavior from linearized experiments that perform only small amplitude perturbations on a limited number of the dimensions. Complete characterization may succeed for bounded component problems, such as an individual cell cycle or signaling cascade, but larger systems problems will require a coarse-grained approach. Hence a new experimental and analytical framework is needed. Possibly one could utilize high-amplitude, multi-variable driving of the system to infer coarse-grained, effective models, which in turn can be tested by their ability to control systems behavior. Navigation at will between attractors in a high-dimensioned dynamical system will provide not only detailed knowledge of the shape of attractor basins, but also measures of underlying stochastic events such as noise in gene expression or receptor binding and how both affect system stability and robustness. Needed for this are wide-bandwidth methods to sense and actuate large numbers of intracellular and extracellular variables and automatically and rapidly infer dynamic control models. The success of this approach may be determined by how broadly the sensors and actuators can span the full dimensionality of the phase space. Supported by the Defense Threat Reduction Agency HDTRA-09-1-0013, NIH National Institute on Drug Abuse RC2DA028981, the National Academies Keck Futures Initiative, and the Vanderbilt Institute for Integrative Biosystems Research and Education.

Analysis of the El Niño/La Niña-Southern Oscillation variability and malaria in the Estado Sucre, Venezuela.

PubMed

Delgado-Petrocelli, Laura; Córdova, Karenia; Camardiel, Alberto; Aguilar, Víctor H; Hernández, Denise; Ramos, Santiago

2012-09-01

The last decade has seen an unprecedented, worldwide acceleration of environmental and climate changes. These processes impact the dynamics of natural systems, which include components associated with human communities such as vector-borne diseases. The dynamics of environmental and climate variables, altered by global change as reported by the Intergovernmental Panel on Climate Change, affect the distribution of many tropical diseases. Complex systems, e.g. the El Niño/La Niña-Southern Oscillation (ENSO), in which environmental variables operate synergistically, can provoke the reemergence and emergence of vector-borne diseases at new sites. This research investigated the influence of ENSO events on malaria incidence by determining the relationship between climate variations, expressed as warm, cold and neutral phases, and their relation to the number of malaria cases in some north-eastern municipalities of Venezuela (Estado Sucre) during the period 1990-2000. Significant differences in malaria incidence were found, particularly in the La Niña ENSO phases (cold) of moderate intensity. These findings should be taken into account for surveillance and control in the future as they shed light on important indicators that can lead to reduced vulnerability to malaria.

Identification and Modelling of the In-Plane Reinforcement Orientation Variations in a CFRP Laminate Produced by Manual Lay-Up

NASA Astrophysics Data System (ADS)

Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri

2017-08-01

Reinforcement angle orientation has a significant effect on the mechanical properties of composite materials. This work presents a methodology to introduce variable reinforcement angles into finite element (FE) models of composite structures. The study of reinforcement orientation variations uses meta-models to identify and control a continuous variation across the composite ply. First, the reinforcement angle is measured through image analysis techniques of the composite plies during the lay-up phase. Image analysis results show that variations in the mean ply orientations are between -0.5 and 0.5° with standard deviations ranging between 0.34 and 0.41°. An automatic post-treatment of the images determines the global and local angle variations yielding good agreements visually and numerically between the analysed images and the identified parameters. A composite plate analysed at the end of the cooling phase is presented as a case of study. Here, the variation in residual strains induced by the variability in the reinforcement orientation are up to 28% of the strain field of the homogeneous FE model. The proposed methodology has shown its capabilities to introduce material and geometrical variability into FE analysis of layered composite structures.

Identification and Modelling of the In-Plane Reinforcement Orientation Variations in a CFRP Laminate Produced by Manual Lay-Up

NASA Astrophysics Data System (ADS)

Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri

2018-06-01

Reinforcement angle orientation has a significant effect on the mechanical properties of composite materials. This work presents a methodology to introduce variable reinforcement angles into finite element (FE) models of composite structures. The study of reinforcement orientation variations uses meta-models to identify and control a continuous variation across the composite ply. First, the reinforcement angle is measured through image analysis techniques of the composite plies during the lay-up phase. Image analysis results show that variations in the mean ply orientations are between -0.5 and 0.5° with standard deviations ranging between 0.34 and 0.41°. An automatic post-treatment of the images determines the global and local angle variations yielding good agreements visually and numerically between the analysed images and the identified parameters. A composite plate analysed at the end of the cooling phase is presented as a case of study. Here, the variation in residual strains induced by the variability in the reinforcement orientation are up to 28% of the strain field of the homogeneous FE model. The proposed methodology has shown its capabilities to introduce material and geometrical variability into FE analysis of layered composite structures.

Circuit design and simulation of a transmit beamforming ASIC for high-frequency ultrasonic imaging systems.

PubMed

Athanasopoulos, Georgios I; Carey, Stephen J; Hatfield, John V

2011-07-01

This paper describes the design of a programmable transmit beamformer application-specific integrated circuit (ASIC) with 8 channels for ultrasound imaging systems. The system uses a 20-MHz reference clock. A digital delay-locked loop (DLL) was designed with 50 variable delay elements, each of which provides a clock with different phase from a single reference. Two phase detectors compare the phase difference of the reference clock with the feedback clock, adjusting the delay of the delay elements to bring the feedback clock signal in phase with the reference clock signal. Two independent control voltages for the delay elements ensure that the mark space ratio of the pulses remain at 50%. By combining a 10- bit asynchronous counter with the delays from the DLL, each channel can be programmed to give a maximum time delay of 51 μs with 1 ns resolution. It can also give bursts of up to 64 pulses. Finally, for a single pulse, it can adjust the pulse width between 9 ns and 100 ns by controlling the current flowing through a capacitor in a one-shot circuit, for use with 40-MHz and 5-MHz transducers, respectively.

Method and apparatus for thermal management of vehicle exhaust systems

DOEpatents

Benson, David K.; Potter, Thomas F.

1995-01-01

A catalytic converter is surrounded by variable conductance insulation for maintaining the operating temperature of the catalytic converter at an optimum level, for inhibiting heat loss when raising catalytic converter temperature to light-off temperature, for storing excess heat to maintain or accelerate reaching light-off temperature, and for conducting excess heat away from the catalytic converter after reaching light-off temperature. The variable conductance insulation includes vacuum gas control and metal-to-metal thermal shunt mechanisms. Radial and axial shielding inhibits radiation and convection heat loss. Thermal storage media includes phase change material, and heat exchanger chambers and fluids carry heat to and from the catalytic converter.

Analytical investigation of the dynamics of tethered constellations in Earth orbit, phase 2

NASA Technical Reports Server (NTRS)

Lorenzini, E.; Arnold, D. A.; Grossi, M. D.; Gullahorn, G. E.

1986-01-01

The development of a two dimensional analytical model that describes the dynamics of an n-mass vertical tethered system is reported. Two different approaches are described: in the first one the control quantities are the independent variables while in the second one the Cartesian coordinates of each mass expressed in the orbiting reference frame are the independent variables. The latter model was used in the 3-mass version to simulate the dynamics of the tethered system in applications involving the displacement of the middle mass along the tether. In particular, issues related to reproducing predetermined acceleration profiles and g-tuning are reported.

Influence of Processing Parameters on the Flow Path in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Schneider, J. A.; Nunes, A. C., Jr.

2006-01-01

Friction stir welding (FSW) is a solid phase welding process that unites thermal and mechanical aspects to produce a high quality joint. The process variables are rpm, translational weld speed, and downward plunge force. The strain-temperature history of a metal element at each point on the cross-section of the weld is determined by the individual flow path taken by the particular filament of metal flowing around the tool as influenced by the process variables. The resulting properties of the weld are determined by the strain-temperature history. Thus to control FSW properties, improved understanding of the processing parameters on the metal flow path is necessary.

Precipitation phase partitioning variability across the Northern Hemisphere

NASA Astrophysics Data System (ADS)

Jennings, K. S.; Winchell, T. S.; Livneh, B.; Molotch, N. P.

2017-12-01

Precipitation phase drives myriad hydrologic, climatic, and biogeochemical processes. Despite its importance, many of the land surface models used to simulate such processes and their sensitivity to climate warming rely on simple, spatially uniform air temperature thresholds to partition rainfall and snowfall. Our analysis of a 29-year dataset with 18.7 million observations of precipitation phase from 12,143 stations across the Northern Hemisphere land surface showed marked spatial variability in the near-surface air temperature at which precipitation is equally likely to fall as rain and snow, the 50% rain-snow threshold. This value averaged 1.0°C and ranged from -0.4°C to 2.4°C for 95% of the stations analyzed. High-elevation continental areas such as the Rocky Mountains of the western U.S. and the Tibetan Plateau of central Asia generally exhibited the warmest thresholds, in some cases exceeding 3.0°C. Conversely, the coldest thresholds were observed on the Pacific Coast of North America, the southeast U.S., and parts of Eurasia, with values dropping below -0.5°C. Analysis of the meteorological conditions during storm events showed relative humidity exerted the strongest control on phase partitioning, with surface pressure playing a secondary role. Lower relative humidity and surface pressure were both associated with warmer 50% rain-snow thresholds. Additionally, we trained a binary logistic regression model on the observations to classify rain and snow events and found including relative humidity as a predictor variable significantly increased model performance between 0.6°C and 3.8°C when phase partitioning is most uncertain. We then used the optimized model and a spatially continuous reanalysis product to map the 50% rain-snow threshold across the Northern Hemisphere. The map reproduced patterns in the observed thresholds with a mean bias of 0.5°C relative to the station data. The above results suggest land surface models could be improved by incorporating relative humidity into their precipitation phase prediction schemes or by using a spatially variable, optimized rain-snow temperature threshold. This is particularly important for climate warming simulations where misdiagnosing a shift from snow to rain or inaccurately quantifying snowfall fraction would likely lead to biased results.

One-leg hop kinematics 20 years following anterior cruciate ligament rupture: Data revisited using functional data analysis.

PubMed

Hébert-Losier, Kim; Pini, Alessia; Vantini, Simone; Strandberg, Johan; Abramowicz, Konrad; Schelin, Lina; Häger, Charlotte K

2015-12-01

Despite interventions, anterior cruciate ligament ruptures can cause long-term deficits. To assist in identifying and treating deficiencies, 3D-motion analysis is used for objectivizing data. Conventional statistics are commonly employed to analyze kinematics, reducing continuous data series to discrete variables. Conversely, functional data analysis considers the entire data series. Here, we employ functional data analysis to examine and compare the entire time-domain of knee-kinematic curves from one-leg hops between and within three groups. All subjects (n=95) were part of a long-term follow-up study involving anterior cruciate ligament ruptures treated ~20 years ago conservatively with physiotherapy only or with reconstructive surgery and physiotherapy, and matched knee-healthy controls. Between-group differences (injured leg, treated groups; non-dominant leg, controls) were identified during the take-off and landing phases, and in the sagittal (flexion/extension) rather than coronal (abduction/adduction) and transverse (internal/external) planes. Overall, surgical and control groups demonstrated comparable knee-kinematic curves. However, compared to controls, the physiotherapy-only group exhibited less flexion during the take-off (0-55% of the normalized phase) and landing (44-73%) phase. Between-leg differences were absent in controls and the surgically treated group, but observed during the flight (4-22%, injured leg>flexion) and the landing (57-85%, injured leg

Using Multigroup-Multiphase Latent State-Trait Models to Study Treatment-Induced Changes in Intra-Individual State Variability: An Application to Smokers' Affect.

PubMed

Geiser, Christian; Griffin, Daniel; Shiffman, Saul

2016-01-01

Sometimes, researchers are interested in whether an intervention, experimental manipulation, or other treatment causes changes in intra-individual state variability. The authors show how multigroup-multiphase latent state-trait (MG-MP-LST) models can be used to examine treatment effects with regard to both mean differences and differences in state variability. The approach is illustrated based on a randomized controlled trial in which N = 338 smokers were randomly assigned to nicotine replacement therapy (NRT) vs. placebo prior to quitting smoking. We found that post quitting, smokers in both the NRT and placebo group had significantly reduced intra-individual affect state variability with respect to the affect items calm and content relative to the pre-quitting phase. This reduction in state variability did not differ between the NRT and placebo groups, indicating that quitting smoking may lead to a stabilization of individuals' affect states regardless of whether or not individuals receive NRT.

Using Multigroup-Multiphase Latent State-Trait Models to Study Treatment-Induced Changes in Intra-Individual State Variability: An Application to Smokers' Affect

PubMed Central

Geiser, Christian; Griffin, Daniel; Shiffman, Saul

2016-01-01

Sometimes, researchers are interested in whether an intervention, experimental manipulation, or other treatment causes changes in intra-individual state variability. The authors show how multigroup-multiphase latent state-trait (MG-MP-LST) models can be used to examine treatment effects with regard to both mean differences and differences in state variability. The approach is illustrated based on a randomized controlled trial in which N = 338 smokers were randomly assigned to nicotine replacement therapy (NRT) vs. placebo prior to quitting smoking. We found that post quitting, smokers in both the NRT and placebo group had significantly reduced intra-individual affect state variability with respect to the affect items calm and content relative to the pre-quitting phase. This reduction in state variability did not differ between the NRT and placebo groups, indicating that quitting smoking may lead to a stabilization of individuals' affect states regardless of whether or not individuals receive NRT. PMID:27499744

Thermodynamics and kinetics of pack aluminide coating formation on IN-100

NASA Technical Reports Server (NTRS)

Levine, S. R.; Caves, R. M.

1973-01-01

An investigation of the effects of pack variables on the formation of aluminide coatings on nickel-base superalloy IN-100 was conducted. Also, the thermodynamics and kinetics of coating formation were analyzed. Observed coating weights were in good agreement with predictions made from the analysis. Pack temperature rather than pack aluminum activity controls the principal coating phase formed. In 1 weight percent aluminum packs, aluminum weight gains were related to the halide pack activator. Solid-state nickel diffusion controlled coating formation from sodium fluoride and chloride and ammonium fluoride activated packs. In other ammonium and sodium halide activated 1 weight percent aluminum packs, gaseous diffusion controlled coating formation.

Adaptive control schemes for improving dynamic performance of efficiency-optimized induction motor drives.

PubMed

Kumar, Navneet; Raj Chelliah, Thanga; Srivastava, S P

2015-07-01

Model Based Control (MBC) is one of the energy optimal controllers used in vector-controlled Induction Motor (IM) for controlling the excitation of motor in accordance with torque and speed. MBC offers energy conservation especially at part-load operation, but it creates ripples in torque and speed during load transition, leading to poor dynamic performance of the drive. This study investigates the opportunity for improving dynamic performance of a three-phase IM operating with MBC and proposes three control schemes: (i) MBC with a low pass filter (ii) torque producing current (iqs) injection in the output of speed controller (iii) Variable Structure Speed Controller (VSSC). The pre and post operation of MBC during load transition is also analyzed. The dynamic performance of a 1-hp, three-phase squirrel-cage IM with mine-hoist load diagram is tested. Test results are provided for the conventional field-oriented (constant flux) control and MBC (adjustable excitation) with proposed schemes. The effectiveness of proposed schemes is also illustrated for parametric variations. The test results and subsequent analysis confer that the motor dynamics improves significantly with all three proposed schemes in terms of overshoot/undershoot peak amplitude of torque and DC link power in addition to energy saving during load transitions. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Paleoenvironmental and Paleoclimate Changes Since 21,000 Cal Years BP in the Northeastern part of Brazil Inferred From Sediment Records in Lagoa do Caco (Maranhao State, Brazil)

NASA Astrophysics Data System (ADS)

Sifeddine, A.; Meyers, P. A.; Gustavo, A.; Spadano Albuquerque, A. L.; Turcq, B.; Campbello Cordeiro, R.; Abrao, J. J.

2004-12-01

Two cores from Caco Lake, Maranhao State (North Brazil) record different histories of sediment accumulation on the margin and center of the lake that reflect changes in lake level. Seismic profiles, mineralogy and organic geochemical studies, backed by radiocarbon dating, reveal variable climatic and environmental conditions over the last 21 Cal Kyr BP. During the Last Glacial Maximum, regional climate was predominantly dry but was interrupted by short humid phases as reflected by a succession of very thin layers of sand and organic matter. The late glacial climate was relatively wet and included two rapid lake-level increases accompanied by forest expansion. The two wet phases were separated by a phase where the lake level remained stable and the forest changes were marked by the development of cool "Podocarpus" forest. These humid climate periods differed significantly from present warm tropical conditions.. The Holocene period is characterized by progressive increase of lake level, which reaches his maximum at around 7,000 Cal years BP. The period between 4,000 Cal years BP and the present shows high variability in lake level. Comparing with other South American and African records, we conclude that Late Glacial humid conditions were controlled by intensification of the ITCZ or shifts of its position, resulting in southeasterly trade wind variations and in interconnection between northern South America and the Atlantic tropical ocean-atmosphere system. The climatic variability during the Holocene is probably the result of sub-Milankovitch solar cycles and regional responses to these global forcings that are related to Atlantic and Pacific variability and their interconnections.

Scheme for rapid adjustment of network impedance

DOEpatents

Vithayathil, John J.

1991-01-01

A static controlled reactance device is inserted in series with an AC electric power transmission line to adjust its transfer impedance. An inductor (reactor) is serially connected with two back-to-back connected thyristors which control the conduction period and hence the effective reactance of the inductor. Additional reactive elements are provided in parallel with the thyristor controlled reactor to filter harmonics and to obtain required range of variable reactance. Alternatively, the static controlled reactance device discussed above may be connected to the secondary winding of a series transformer having its primary winding connected in series to the transmission line. In a three phase transmission system, the controlled reactance device may be connected in delta configuration on the secondary side of the series transformer to eliminate triplen harmonics.

Resonance: The science behind the art of sonic drilling

NASA Astrophysics Data System (ADS)

Lucon, Peter Andrew

The research presented in this dissertation quantifies the system dynamics and the influence of control variables of a sonic drill system. The investigation began with an initial body of work funded by the Department of Energy under a Small Business Innovative Research Phase I Grant, grant number: DE-FG02-06ER84618, to investigate the feasibility of using sonic drills to drill micro well holes to depths of 1500 feet. The Department of Energy funding enabled feasibility testing using a 750 hp sonic drill owned by Jeffery Barrow, owner of Water Development Co. During the initial feasibility testing, data was measured and recorded at the sonic drill head while the sonic drill penetrated to a depth of 120 feet. To demonstrate feasibility, the system had to be well understood to show that testing of a larger sonic drill could simulate the results of drilling a micro well hole of 2.5 inch diameter. A first-order model of the system was developed that produced counter-intuitive findings that enabled the feasibility of using this method to drill deeper and produce micro-well holes to 1500 feet using sonic drills. Although funding was not continued, the project work continued. This continued work expanded on the sonic drill models by understanding the governing differential equation and solving the boundary value problem, finite difference methods, and finite element methods to determine the significance of the control variables that can affect the sonic drill. Using a design of experiment approach and commercially available software, the significance of the variables to the effectiveness of the drill system were determined. From the significant variables, as well as the real world testing, a control system schematic for a sonic drill was derived and is patent pending. The control system includes sensors, actuators, personal logic controllers, as well as a human machine interface. It was determined that the control system should control the resonant mode and the weight on the bit as the primary two control variables. The sonic drill can also be controlled using feedback from sensors mounted on the sonic drill head, which is the driver for the sonic drill located above ground

Multi-segmental postural coordination in professional ballet dancers.

PubMed

Kiefer, Adam W; Riley, Michael A; Shockley, Kevin; Sitton, Candace A; Hewett, Timothy E; Cummins-Sebree, Sarah; Haas, Jacqui G

2011-05-01

Ballet dancers have heightened balance skills, but previous studies that compared dancers to non-dancers have not quantified patterns of multi-joint postural coordination. This study utilized a visual tracking task that required professional ballet dancers and untrained control participants to sway with the fore-aft motion of a target while standing on one leg, at target frequencies of 0.2 and 0.6Hz. The mean and variability of relative phase between the ankle and hip, and measures from cross-recurrence quantification analysis (i.e., percent cross-recurrence, percent cross-determinism, and cross-maxline), indexed the coordination patterns and their stability. Dancers exhibited less variable ankle-hip coordination and a less deterministic ankle-hip coupling, compared to controls. The results indicate that ballet dancers have increased coordination stability, potentially achieved through enhanced neuromuscular control and/or perceptual sensitivity, and indicate proficiency at optimizing the constraints that enable dancers to perform complex balance tasks. Copyright © 2011 Elsevier B.V. All rights reserved.

A Distributed Sensor Network for the Control of a Bioclimatic House in Spain

PubMed Central

Gutiérrez, Álvaro; Jiménez-Leube, Javier; Magdalena, Luis

2009-01-01

The XXI century home should be a digital habitat, a connected residence, but at the same time it should be involved in sustainability and the environment. The location of new technologies at home, and its acceptance by the user, requires, among other actions, a significant diffusion and activity to be undertaken. This work proposes the development of a Smart House network designed for its integration into a sustainable and bioclimatic solar house. The paper focuses on a specific aspect of the house design, the control system bus, developed for the management of the different parameters, variables, sensors and actuators which coexist at home. Finally, the system has been installed in a laboratory bioclimatic house. Environmental variable experiments based on the control of passive elements, such as phase shift gels, are presented. Experimental results show that the system is able to benefit from the bioclimatic elements in the house by taking into account the user preferences. PMID:22408501

A distributed sensor network for the control of a bioclimatic house in Spain.

PubMed

Gutiérrez, Alvaro; Jiménez-Leube, Javier; Magdalena, Luis

2009-01-01

The XXI century home should be a digital habitat, a connected residence, but at the same time it should be involved in sustainability and the environment. The location of new technologies at home, and its acceptance by the user, requires, among other actions, a significant diffusion and activity to be undertaken. This work proposes the development of a Smart House network designed for its integration into a sustainable and bioclimatic solar house. The paper focuses on a specific aspect of the house design, the control system bus, developed for the management of the different parameters, variables, sensors and actuators which coexist at home. Finally, the system has been installed in a laboratory bioclimatic house. Environmental variable experiments based on the control of passive elements, such as phase shift gels, are presented. Experimental results show that the system is able to benefit from the bioclimatic elements in the house by taking into account the user preferences.

ON states as resource units for universal quantum computation with photonic architectures

NASA Astrophysics Data System (ADS)

Sabapathy, Krishna Kumar; Weedbrook, Christian

2018-06-01

Universal quantum computation using photonic systems requires gates the Hamiltonians of which are of order greater than quadratic in the quadrature operators. We first review previous proposals to implement such gates, where specific non-Gaussian states are used as resources in conjunction with entangling gates such as the continuous-variable versions of controlled-phase and controlled-not gates. We then propose ON states which are superpositions of the vacuum and the N th Fock state, for use as non-Gaussian resource states. We show that ON states can be used to implement the cubic and higher-order quadrature phase gates to first order in gate strength. There are several advantages to this method such as reduced number of superpositions in the resource state preparation and greater control over the final gate. We also introduce useful figures of merit to characterize gate performance. Utilizing a supply of on-demand resource states one can potentially scale up implementation to greater accuracy, by repeated application of the basic circuit.

Induced sadness increases persistence in a simulated slot machine task among recreational gamblers.

PubMed

Devos, Gaëtan; Clark, Luke; Maurage, Pierre; Billieux, Joël

2018-05-01

Gambling may constitute a strategy for coping with depressive mood, but a direct influence of depressive mood on gambling behaviors has never been tested via realistic experimental designs in gamblers. The current study tested whether experimentally induced sadness increases persistence on a simulated slot machine task using real monetary reinforcement in recreational gamblers. Sixty participants were randomly assigned to an experimental (sadness induction) or control (no emotional induction) condition, and then performed a slot machine task consisting of a mandatory phase followed by a persistence phase. Potential confounding variables (problem gambling symptoms, impulsivity traits, gambling cognitions) were measured to ensure that the experimental and control groups were comparable. The study showed that participants in the sadness condition displayed greater gambling persistence than control participants (p = .011). These data support the causal role of negative affect in decisions to gamble and persistence, which bears important theoretical and clinical implications. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Howling at the moon? The effect of lunar phases on post-surgical pain outcome.

PubMed

Komann, Marcus; Weinmann, Claudia; Meissner, Winfried

2014-05-01

Many people are convinced that lunar phases influence their lives - despite the fact that a lot of studies have shown that this belief is wrong. In this article, we investigate the effect of lunar phases on acute post-surgical pain and on treatment-related side effects. We hypothesize that there is no influence. The data for the study were collected in 2010 and 2011 in 10 international hospitals participating in the research project PAIN OUT. Hospitalized patients were asked for their pain after surgery and pain treatment side effects using numerical ratings scales from 0 to 10. We applied Kurskal-Wallis H-tests to find out if the four moon phases show significant differences in 14 outcome variables. Afterwards, we adjusted for age, gender and three tracer surgeries. A total of 12,224 patient data sets were assessed. For most variables and sub-groups, there is no lunar effect on the observed outcome variables. The only items that show statistically significant differences are pain interference with sleep (p = 0.01) and drowsiness (p = 0.01). The only sub-groups that show statistically significant connections to lunar phases in some variables are men (7 out of 14 variables significant) and elderly people (4 out of 14 variables significant). Even in the statistically significant sub-groups, the differences are small and only show up in some variables. We conclude that lunar phases have no effect on post-surgical pain or its side effects. The hypothesis holds. Thus, there is no reason for patients to postpone surgeries or to fear surgeries on any given date.

Congenital central hypoventilation syndrome (CCHS): Circadian temperature variation.

PubMed

Saiyed, Rehan; Rand, Casey M; Carroll, Michael S; Koliboski, Cynthia M; Stewart, Tracey M; Brogadir, Cindy D; Kenny, Anna S; Petersen, Emily K E; Carley, David W; Weese-Mayer, Debra E

2016-03-01

Congenital central hypoventilation syndrome (CCHS) is a rare neurocristopathy, which includes a control of breathing deficit and features of autonomic nervous system (ANS) dysregulation. In recognition of the fundamental role of the ANS in temperature regulation and rhythm and the lack of any prior characterization of circadian temperature rhythms in CCHS, we sought to explore peripheral and core temperatures and circadian patterning. We hypothesized that CCHS patients would exhibit lower peripheral skin temperatures (PST), variability, and circadian rhythmicity (vs. controls), as well as a disrupted relationship between core body temperature (CBT) and PST. PST was sampled every 3 min over four 24-hr periods in CCHS cases and similarly aged controls. CBT was sampled in a subset of these recordings. PST was recorded from 25 CCHS cases (110,664 measures/230 days) and 39 controls (78,772 measures/164 days). Simultaneous CBT measurements were made from 23 CCHS patients. In CCHS, mean PST was lower overall (P = 0.03) and at night (P = 0.02), and PST variability (interquartile range) was higher at night (P = 0.05) (vs. controls). PST circadian rhythm remained intact but the phase relationship of PST to CBT rhythm was extremely variable in CCHS. PST alterations in CCHS likely reflect altered autonomic control of peripheral vascular tone. These alterations represent a previously unreported manifestation of CCHS and may provide an opportunity for therapeutic intervention. The relationship between temperature dysregulation and CCHS may also offer insight into basic mechanisms underlying thermoregulation. © 2015 Wiley Periodicals, Inc.

Optimal Control of Thermo--Fluid Phenomena in Variable Domains

NASA Astrophysics Data System (ADS)

Volkov, Oleg; Protas, Bartosz

2008-11-01

This presentation concerns our continued research on adjoint--based optimization of viscous incompressible flows (the Navier--Stokes problem) coupled with heat conduction involving change of phase (the Stefan problem), and occurring in domains with variable boundaries. This problem is motivated by optimization of advanced welding techniques used in automotive manufacturing, where the goal is to determine an optimal heat input, so as to obtain a desired shape of the weld pool surface upon solidification. We argue that computation of sensitivities (gradients) in such free--boundary problems requires the use of the shape--differential calculus as a key ingredient. We also show that, with such tools available, the computational solution of the direct and inverse (optimization) problems can in fact be achieved in a similar manner and in a comparable computational time. Our presentation will address certain mathematical and computational aspects of the method. As an illustration we will consider the two--phase Stefan problem with contact point singularities where our approach allows us to obtain a thermodynamically consistent solution.

Early Results from the Lunar Atmosphere and Dust Environment Explorer (LADEE)

NASA Technical Reports Server (NTRS)

Elphic, R. C.; Hine, B.; Delory, G. T.; Mahaffy, Paul; Benna, Mehdi; Horanyi, Mihaly; Colaprete, Anthony; Noble, Sarah

2014-01-01

On 6 September, 2013, a near-perfect launch of the first Minotaur V rocket successfully carried NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) into a high-eccentricity geocentric orbit. After 30 days of phasing, LADEE arrived at the Moon on 6 October, 2013. LADEE's science objectives are twofold: (1) Determine the composition of the lunar atmosphere, investigate processes controlling its distribution and variability, including sources, sinks, and surface interactions; (2) Characterize the lunar exospheric dust environment, measure its spatial and temporal variability, and effects on the lunar atmosphere, if any. After a successful commissioning phase, the three science instruments have made systematic observations of the lunar dust and exospheric environment. These include initial observations of argon, neon and helium exospheres, and their diurnal variations; the lunar micrometeoroid impact ejecta cloud and its variations; spatial and temporal variations of the sodium exosphere; and the search for sunlight extinction caused by dust. LADEE also made observations of the effects of the Chang'e 3 landing on 14 December 2013.

NASA Tech Briefs, July 2006

NASA Technical Reports Server (NTRS)

2006-01-01

Topics covered include: Airport Remote Tower Sensor Systems; Implantable Wireless MEMS Sensors for Medical Uses; Embedded Sensors for Measuring Surface Regression; Coordinating an Autonomous Earth-Observing Sensorweb; Range-Measuring Video Sensors; Stability Enhancement of Polymeric Sensing Films Using Fillers; Sensors for Using Times of Flight to Measure Flow Velocities; Receiver Would Control Phasing of a Phased-Array Antenna; Modern Design of Resonant Edge-Slot Array Antennas; Carbon-Nanotube Schottky Diodes; Simplified Optics and Controls for Laser Communications; Coherent Detection of High-Rate Optical PPM Signals; Multichannel Phase and Power Detector; Using Satellite Data in Weather Forecasting: I; Using Dissimilarity Metrics to Identify Interesting Designs; X-Windows PVT Widget Class; Shuttle Data Center File-Processing Tool in Java; Statistical Evaluation of Utilization of the ISS; Nanotube Dispersions Made With Charged Surfactant; Aerogels for Thermal Insulation of Thermoelectric Devices; Low-Density, Creep-Resistant Single-Crystal Superalloys; Excitations for Rapidly Estimating Flight-Control Parameters; Estimation of Stability and Control Derivatives of an F-15; Tool for Coupling a Torque Wrench to a Round Cable Connector; Ultrasonically Actuated Tools for Abrading Rock Surfaces; Active Struts With Variable Spring Stiffness and Damping; Multiaxis, Lightweight, Computer-Controlled Exercise System; Dehydrating and Sterilizing Wastes Using Supercritical CO2; Alpha-Voltaic Sources Using Liquid Ga as Conversion Medium; Ice-Borehole Probe; Alpha-Voltaic Sources Using Diamond as Conversion Medium; White-Light Whispering-Gallery-Mode Optical Resonators; Controlling Attitude of a Solar-Sail Spacecraft Using Vanes; and Wire-Mesh-Based Sorber for Removing Contaminants from Air.

Volumetric capnography for the evaluation of pulmonary disease in adult patients with cystic fibrosis and noncystic fibrosis bronchiectasis.

PubMed

Veronez, L; Moreira, M M; Soares, S T P; Pereira, M C; Ribeiro, M A G O; Ribeiro, J D; Terzi, R G G; Martins, L C; Paschoal, I A

2010-06-01

This study was designed to use volumetric capnography to evaluate the breathing pattern and ventilation inhomogeneities in patients with chronic sputum production and bronchiectasis and to correlate the phase 3 slope of the capnographic curve to spirometric measurements. Twenty-four patients with cystic fibrosis (CF) and 21 patients with noncystic fibrosis idiopathic bronchiectasis (BC) were serially enrolled. The diagnosis of cystic fibrosis was based on the finding of at least two abnormal sweat chloride concentrations (iontophoresis sweat test). The diagnosis of bronchiectasis was made when the patient had a complaint of chronic sputum production and compatible findings at high-resolution computed tomography (HRCT) scan of the thorax. Spirometric tests and volumetric capnography were performed. The 114 subjects of the control group for capnographic variables were nonsmoker volunteers, who had no respiratory symptoms whatsoever and no past or present history of lung disease. Compared with controls, patients in CF group had lower SpO(2) (P < 0.0001), higher respiratory rates (RR) (P < 0.0001), smaller expiratory volumes normalized for weight (V(E)/kg) (P < 0.028), smaller expiratory times (Te) (P < 0.0001), and greater phase 3 Slopes normalized for tidal volume (P3Slp/V(E)) (P < 0.0001). Compared with controls, patients in the BC group had lower SpO(2) (P < 0.0001), higher RR (P < 0.004), smaller V(E)/kg (P < 0.04), smaller Te (P < 0.007), greater P3Slp/V(E) (P < 0.0001), and smaller VCO(2) (P < 0.0002). The pooled data from the two patient groups compared with controls showed that the patients had lower SpO(2) (P < 0.0001), higher RR (P < 0.0001), smaller V(E)/kg (P < 0.05), smaller Te (P < 0.0001), greater P3Slp/V(E) (P < 0.0001), and smaller VCO(2) (P < 0.0003). All of the capnographic and spirometric variables evaluated showed no significant differences between CF and BC patients. Spirometric data in this study reveals that the patients had obstructive defects with concomitant low vital capacities and both groups had very similar abnormalities. The capnographic variables in the patient group suggest a restrictive respiratory pattern (greater respiratory rates, smaller expiratory times and expiratory volumes, normal peak expiratory flows). Both groups of patients showed increased phase III slopes compared with controls, which probably indicates the presence of diffuse disease of small airways in both conditions leading to inhomogeneities of ventilation.

Dynamic flashing yellow arrow (FYA): a study on variable left-turn mode operational and safety impacts phase II - model expansion and testing.

DOT National Transportation Integrated Search

2016-06-01

The flashing yellow arrow (FYA) signal display creates an opportunity to enhance the left-turn phase with a : variable mode that can be changed on demand. The previously developed decision support system (DSS) in : phase I facilitated the selection o...

REGULATION OF GEOGRAPHIC VARIABILITY IN HAPLOID:DIPLOD RATIOS OF BIPHASIC SEAWEED LIFE CYCLES(1).

PubMed

da Silva Vieira, Vasco Manuel Nobre de Carvalho; Santos, Rui Orlando Pimenta

2012-08-01

The relative abundance of haploid and diploid individuals (H:D) in isomorphic marine algal biphasic cycles varies spatially, but only if vital rates of haploid and diploid phases vary differently with environmental conditions (i.e. conditional differentiation between phases). Vital rates of isomorphic phases in particular environments may be determined by subtle morphological or physiological differences. Herein, we test numerically how geographic variability in H:D is regulated by conditional differentiation between isomorphic life phases and the type of life strategy of populations (i.e. life cycles dominated by reproduction, survival or growth). Simulation conditions were selected using available data on H:D spatial variability in seaweeds. Conditional differentiation between ploidy phases had a small effect on the H:D variability for species with life strategies that invest either in fertility or in growth. Conversely, species with life strategies that invest mainly in survival, exhibited high variability in H:D through a conditional differentiation in stasis (the probability of staying in the same size class), breakage (the probability of changing to a smaller size class) or growth (the probability of changing to a bigger size class). These results were consistent with observed geographic variability in H:D of natural marine algae populations. © 2012 Phycological Society of America.

Analysis of stimulus-related activity in rat auditory cortex using complex spectral coefficients

PubMed Central

Krause, Bryan M.

2013-01-01

The neural mechanisms of sensory responses recorded from the scalp or cortical surface remain controversial. Evoked vs. induced response components (i.e., changes in mean vs. variance) are associated with bottom-up vs. top-down processing, but trial-by-trial response variability can confound this interpretation. Phase reset of ongoing oscillations has also been postulated to contribute to sensory responses. In this article, we present evidence that responses under passive listening conditions are dominated by variable evoked response components. We measured the mean, variance, and phase of complex time-frequency coefficients of epidurally recorded responses to acoustic stimuli in rats. During the stimulus, changes in mean, variance, and phase tended to co-occur. After the stimulus, there was a small, low-frequency offset response in the mean and modest, prolonged desynchronization in the alpha band. Simulations showed that trial-by-trial variability in the mean can account for most of the variance and phase changes observed during the stimulus. This variability was state dependent, with smallest variability during periods of greatest arousal. Our data suggest that cortical responses to auditory stimuli reflect variable inputs to the cortical network. These analyses suggest that caution should be exercised when interpreting variance and phase changes in terms of top-down cortical processing. PMID:23657279

Design and Methods of a Randomized Trial of Continuous Glucose Monitoring in Persons With Type 1 Diabetes With Impaired Glycemic Control Treated With Multiple Daily Insulin Injections (GOLD Study).

PubMed

Lind, Marcus; Polonsky, William; Hirsch, Irl B; Heise, Tim; Bolinder, Jan; Dahlqvist, Sofia; Pehrsson, Nils-Gunnar; Moström, Peter

2016-05-01

The majority of individuals with type 1 diabetes today have glucose levels exceeding guidelines. The primary aim of this study was to evaluate whether continuous glucose monitoring (CGM), using the Dexcom G4 stand-alone system, improves glycemic control in adults with type 1 diabetes treated with multiple daily insulin injections (MDI). Individuals with type 1 diabetes and inadequate glycemic control (HbA1c ≥ 7.5% = 58 mmol/mol) treated with MDI were randomized in a cross-over design to the Dexcom G4 versus conventional care for 6 months followed by a 4-month wash-out period. Masked CGM was performed before randomization, during conventional treatment, and during the wash-out period to evaluate effects on hypoglycemia, hyperglycemia, and glycemic variability. Questionnaires were used to evaluate diabetes treatment satisfaction, fear of hypoglycemia, hypoglycemia confidence, diabetes-related distress, overall well-being, and physical activity during the different phases of the trial. The primary endpoint was the difference in HbA1c at the end of each treatment phase. A total of 205 patients were screened, of whom 161 were randomized between February and December 2014. Study completion is anticipated in April 2016. It is expected that the results of this study will establish whether using the Dexcom G4 stand-alone system in individuals with type 1 diabetes treated with MDI improves glycemic control, reduces hypoglycemia, and influences quality-of-life indicators and glycemic variability. © 2016 Diabetes Technology Society.

Two-phase strategy of neural control for planar reaching movements: II--relation to spatiotemporal characteristics of movement trajectory.

PubMed

Rand, Miya K; Shimansky, Yury P

2013-09-01

In the companion paper utilizing a quantitative model of optimal motor coordination (Part I, Rand and Shimansky, in Exp Brain Res 225:55-73, 2013), we examined coordination between X and Y movement directions (XYC) during reaching movements performed under three prescribed speeds, two movement amplitudes, and two target sizes. The obtained results indicated that the central nervous system (CNS) utilizes a two-phase strategy, where the initial and the final phases correspond to lower and higher precision of information processing, respectively, for controlling goal-directed reach-type movements to optimize the total cost of task performance including the cost of neural computations. The present study investigates how two different well-known concepts used for describing movement performance relate to the concepts of optimal XYC and two-phase control strategy. First, it is examined to what extent XYC is equivalent to movement trajectory straightness. The data analysis results show that the variability, the movement trajectory's deviation from the straight line, increases with an increase in prescribed movement speed. In contrast, the dependence of XYC strength on movement speed is opposite (in total agreement with an assumption of task performance optimality), suggesting that XYC is a feature of much higher level of generality than trajectory straightness. Second, it is tested how well the ballistic and the corrective components described in the traditional concept of two-component model of movement performance match with the initial and the final phase of the two-phase control strategy, respectively. In fast reaching movements, the percentage of trials with secondary corrective submovement was smaller under larger-target shorter-distance conditions. In slower reaching movements, meaningful parsing was impossible due to massive fluctuations in the kinematic profile throughout the movement. Thus, the parsing points determined by the conventional submovement analysis did not consistently reflect separation between the ballistic and error-corrective components. In contrast to the traditional concept of two-component movement performance, the concept of two-phase control strategy is applicable to a wide variety of experimental conditions.

Future shift of the relative roles of precipitation and temperature in controlling annual runoff in the conterminous United States

Treesearch

Kai Duan; Ge Sun; Steven G. McNulty; Peter V. Caldwell; Erika C. Cohen; Shanlei Sun; Heather D. Aldridge; Decheng Zhou; Liangxia Zhang; Yang Zhang

2017-01-01

This study examines the relative roles of cli- matic variables in altering annual runoff in the contermi- nous United States (CONUS) in the 21st century, using a monthly ecohydrological model (the Water Supply Stress In- dex model, WaSSI) driven with historical records and future scenarios constructed from 20 Coupled Model Intercompar- ison Project Phase 5 (CMIP5)...

Walking in water and on land after an incomplete spinal cord injury.

PubMed

Tamburella, Federica; Scivoletto, Giorgio; Cosentino, Elena; Molinari, Marco

2013-10-01

Although no data are available on the effects of water environment on the gait of subjects with spinal cord injury (SCI), hydrotherapy is used in the rehabilitation protocols of SCI patients. The aim of this study was to characterize gait features of subjects with incomplete SCI walking in water and on land in comparison with healthy controls (CTRLs) to identify the specificity of water environment on influencing gait in SCI subjects. This is a matched case-control study. Kinematic gait parameters and range of motion of joint angles of 15 SCI subjects and 15 CTRLs were analyzed. Compared with gait on land, gait in water of the SCI patients was characterized by speed and stance phase reduction, gait cycle time increment, and invariance of stride length and range of motion values. Comparison with CTRL data remarked that walking in water reduces gait differences between the groups. Furthermore, in water, the SCI subjects presented a reduction in variability of the hip and knee joint angles, whereas in the CTRLs, a larger variability was observed. Gait in water of the SCI subjects is associated with kinematic parameters more similar to those of the CTRLs, particularly regarding speed, stride length, and stance phase, supporting the idea that walking in a water environment may be of rehabilitative significance for SCI subjects.

Anthropometrics and Body Composition in Adults with High-Grade Gliomas: Effects of Disease-Related Variables.

PubMed

Bertoli, Simona; Battezzati, Alberto; Petruzzi, Alessandra; Leone, Alessandro; De Amicis, Ramona; Tramacere, Elena; Meda, Maddalena; Foppiani, Andrea; Silvani, Antonio; Lamperti, Elena

2018-04-01

Nutritional status in adults with high-grade gliomas (HGGs) has been poorly investigated. We studied anthropometrics and fat mass (FM), fat free mass (FFM), and body water in HGGs patients also in relation to disease-related variables. Fifty-one patients (17 III and 34 IV-grade) and fifty-one control group (CG) matched for sex, age, and BMI were enrolled. Neurological scales, anthropometry, bioimpedance, and blood sampling were performed and analyzed according to grade, lesion location, extent of resection, phase of treatment, current steroids and antiepileptic therapy, and age of patient. 41.2% were overweight and 15.7% obese. Compared to the CG, HGGs had similar anthropometrics and body composition. IV-grade, compared to the III, had higher BMI, waist circumference, FM and lower FFM. Only patients during concomitant radio and chemotherapy showed a negative BMI variation from baseline. In conclusion, overnutrition occurs in almost 6 out of 10 HGGs patients and is more relevant in IV-grade. Throughout all the treatment phases, there is a higher risk of weight loss occurred only during concomitant radio and chemotherapy. Body composition showed no specific features compared to controls. These results may assist intervention studies directed towards neurometabolic dietary treatment. Nutritional screening is warranted during the time course of disease.

Temporal and spatial behavior of pharmaceuticals in ...

EPA Pesticide Factsheets

The behavior of active pharmaceutical ingredients (APIs) in urban estuaries is not well understood. In this study, 15 high volume usage APIs were measured over a one year period throughout Narragansett Bay, RI, USA to determine factors controlling their concentration and distribution. Dissolved APIs ranged in concentration from not detected to 310 ng/L, with numerous APIs present at all sites and sampling periods. Eight APIs were present in suspended particulate material, ranging in concentration from <1 ng/g to 44 ng/g. Partitioning coefficients (Kds) were determined for APIs present in both the dissolved and particulate phases, with their range and variability remaining relatively constant during the study. Organic carbon normalization reduced the observed variability of several APIs to a small extent; however, other factors appear to play a role in controlling partitioning behavior. The continuous discharge of wastewater treatment plant effluents into upper Narragansett Bay resulted in sustained levels of APIs, resulting in a zone of “pseudo-persistence.” For most of the APIs, there was a strong relationship with salinity, indicating conservative behavior within the estuary. Short flushing times in Narragansett Bay coupled with APIs present primarily in the dissolved phase suggests that most APIs will be diluted and transported out of the estuary, with only small amounts of several compounds removed to and sequestered in sediments. This study ide

Synthesis of sub-10 nm solid lipid nanoparticles for topical and biomarker detection applications

NASA Astrophysics Data System (ADS)

Calderón-Colón, Xiomara; Patchan, Marcia W.; Theodore, Mellisa L.; Le, Huong T.; Sample, Jennifer L.; Benkoski, Jason J.; Patrone, Julia B.

2014-02-01

Solid lipid nanoparticles (SLNs) are a promising platform for sensing in vivo biomarkers due to their biocompatibility, stability, and their ability to carry a wide range of active ingredients. The skin is a prominent target organ for numerous inflammatory and stress-related biomarkers, making it an excellent site for early detection of physiological imbalance and application of sensory nanoparticles. Though smaller particle size has generally been correlated with increased penetration of skin models, there has been little attention paid to the significance of other nanoparticle synthesis parameters with respect to their physical properties. In this study, we demonstrate the synthesis of sub-10 nm SLNs by the phase inversion temperature (PIT) method. These particles were specifically designed for topical delivery of hydrogen peroxide-detecting chemiluminescent dyes. A systematic design of experiments approach was used to investigate the role of the processing variables on SLN form and properties. The processing variables were correlated with the SLN properties (e.g., dye solubility, phase inversion temperature, particle size, polydispersity, melting point, and latent heat of melting). Statistical analysis revealed that the PIT method, while allowing total control over the thermal properties, resulted in well-controlled synthesis of ultra-small particles, while allowing great flexibility in the processing conditions and incorporated compounds.

Flight control systems properties and problems, volume 1

NASA Technical Reports Server (NTRS)

Mcruer, D. T.; Johnston, D. E.

1975-01-01

This volume contains a delineation of fundamental and mechanization-specific flight control characteristics and problems gleaned from many sources and spanning a period of over two decades. It is organized to present and discuss first some fundamental, generic problems of closed-loop flight control systems involving numerator characteristics (quadratic dipoles, non-minimum phase roots, and intentionally introduced zeros). Next the principal elements of the largely mechanical primary flight control system are reviewed with particular emphasis on the influence of nonlinearities. The characteristics and problems of augmentation (damping, stability, and feel) system mechanizations are then dealt with. The particular idiosyncracies of automatic control actuation and command augmentation schemes are stressed, because they constitute the major interfaces with the primary flight control system and an often highly variable vehicle response.

Adaptive data rate SSMA system for personal and mobile satellite communications

NASA Technical Reports Server (NTRS)

Ikegami, Tetsushi; Takahashi, Takashi; Arakaki, Yoshiya; Wakana, Hiromitsu

1995-01-01

An adaptive data rate SSMA (spread spectrum multiple access) system is proposed for mobile and personal multimedia satellite communications without the aid of system control earth stations. This system has a constant occupied bandwidth and has variable data rates and processing gains to mitigate communication link impairments such as fading, rain attenuation and interference as well as to handle variable data rate on demand. Proof of concept hardware for 6MHz bandwidth transponder is developed, that uses offset-QPSK (quadrature phase shift keying) and MSK (minimum shift keying) for direct sequence spread spectrum modulation and handle data rates of 4k to 64kbps. The RS422 data interface, low rate voice and H.261 video codecs are installed. The receiver is designed with coherent matched filter technique to achieve fast code acquisition, AFC (automatic frequency control) and coherent detection with minimum hardware losses in a single matched filter circuit. This receiver structure facilitates variable data rate on demand during a call. This paper shows the outline of the proposed system and the performance of the prototype equipment.

Repetitive transcranial magnetic stimulator with controllable pulse parameters

NASA Astrophysics Data System (ADS)

Peterchev, Angel V.; Murphy, David L.; Lisanby, Sarah H.

2011-06-01

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT) modules to generate near-rectangular electric field pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable pulse parameter TMS (cTMS) device can induce electric field pulses with phase widths of 10-310 µs and positive/negative phase amplitude ratio of 1-56. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation up to 82% and 57% and decreases coil heating up to 33% and 41%, respectively. We demonstrate repetitive TMS trains of 3000 pulses at frequencies up to 50 Hz with electric field pulse amplitude and width variability less than the measurement resolution (1.7% and 1%, respectively). Offering flexible pulse parameter adjustment and reduced power consumption and coil heating, cTMS enhances existing TMS paradigms, enables novel research applications and could lead to clinical applications with potentially enhanced potency.

Repetitive transcranial magnetic stimulator with controllable pulse parameters.

PubMed

Peterchev, Angel V; Murphy, David L; Lisanby, Sarah H

2011-06-01

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT) modules to generate near-rectangular electric field pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable pulse parameter TMS (cTMS) device can induce electric field pulses with phase widths of 10-310 µs and positive/negative phase amplitude ratio of 1-56. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation up to 82% and 57% and decreases coil heating up to 33% and 41%, respectively. We demonstrate repetitive TMS trains of 3000 pulses at frequencies up to 50 Hz with electric field pulse amplitude and width variability less than the measurement resolution (1.7% and 1%, respectively). Offering flexible pulse parameter adjustment and reduced power consumption and coil heating, cTMS enhances existing TMS paradigms, enables novel research applications and could lead to clinical applications with potentially enhanced potency.

Alabama Coronary Artery Bypass Grafting Project

PubMed Central

Holman, William L.; Sansom, Monique; Kiefe, Catarina I.; Peterson, Eric D.; Hubbard, Steve G.; Delong, James F.; Allman, Richard M.

2004-01-01

Objective/Background: This report describes the first round of results for Phase II of the Alabama CABG Project, a regional quality improvement initiative. Methods: Charts submitted by all hospitals in Alabama performing CABG (ICD-9 codes 36.10–36.20) were reviewed by a Clinical Data Abstraction Center (CDAC) (preintervention 1999–2000; postintervention 2000–2001). Variables that described quality in Phase I were abstracted for Phase II and data describing the new variables of β-blocker use and lipid management were collected. Data samples collected onsite by participating hospitals were used for rapid cycle improvement in Phase II. Results: CDAC data (n = 1927 cases in 1999; n = 2001 cases in 2000) showed that improvements from Phase I in aspirin prescription, internal mammary artery use, and duration of intubation persisted in Phase II. During Phase II, use of β-blockers before, during, or after CABG increased from 65% to 76% of patients (P < 0.05). Appropriate lipid management, an aggregate variable, occurred in 91% of patients before and 91% after the educational intervention. However, there were improvements in 3 of 5 subcategories for lipid management (documenting a lipid disorder [52%–57%], initiating drug therapy [45%–53%], and dietary counseling [74%–91%]; P < 0.05). Conclusions: In Phase II, this statewide process-oriented quality improvement program added two new measures of quality. Achievements of quality improvement from Phase I persisted in Phase II, and improvements were seen in the new variables of lipid management and perioperative use of β-blockers. PMID:14685107

Comparison of broiler performance when fed diets containing event DP-3O5423-1, nontransgenic near-isoline control, or commercial reference soybean meal, hulls, and oil.

PubMed

McNaughton, J; Roberts, M; Smith, B; Rice, D; Hinds, M; Sanders, C; Layton, R; Lamb, I; Delaney, B

2008-12-01

DP-3Ø5423-1 (305423) is a genetically modified soybean that was produced by biolistic insertion of the gm-fad2-1 gene fragment and gm-hra genes into the germline of soybean seeds. Expression of gm-fad2-1 results in greater concentrations of oleic acid (18:1) by suppressing expression of the endogenous FAD2-1 gene, which encodes an n-6 fatty acid desaturase enzyme that catalyzes desaturation of 18:1 to linoleic acid (18:2). The GM-HRA protein expressed by the gm-hra gene is a modified version of the soybean acetolactate synthase enzyme that is used as a selectable marker during transformation. A 42-d feeding trial was conducted with broiler chickens to compare the nutritional performance of 305423 soybeans with nontransgenic soybeans. Diets were prepared using processed fractions (meal, hulls, and oil) from 305423 soybean plants. For comparison, additional diets were produced with soybean fractions obtained from a nontransgenic near-isoline (control) and nontransgenic commercial Pioneer brand varieties (93B86, 93B15, and 93M40). Diets were fed to Ross x Cobb broilers (n = 120/group, 50% male and 50% female) in 3 phases. Starter, grower, and finisher diets contained 26.5, 23, and 21.5% soybean meal, respectively. Soybean hulls and oil were added at 1.0 and 0.5%, respectively, across all diets in each phase. No statistically significant differences were observed in growth performance (BW, mortality, feed efficiency), organ yield (liver and kidney), or carcass yield (breast, thigh, leg, wing, and abdominal fat) variables between broilers consuming diets prepared with isolated fractions from 305423 or near-isoline control soybean. Additionally, all performance and carcass variables from control and 305423 soybean treatment groups fell within tolerance intervals constructed for each response variable using data from broilers fed diets prepared with reference soybean fractions. Based on the results from this study, it was concluded that 305423 soybeans were nutritionally equivalent to non-transgenic control soybeans with a comparable genetic background.

A guide for measurement of circulating metabolic hormones in rodents: Pitfalls during the pre-analytical phase

PubMed Central

Bielohuby, Maximilian; Popp, Sarah; Bidlingmaier, Martin

2012-01-01

Researchers analyse hormones to draw conclusions from changes in hormone concentrations observed under specific physiological conditions and to elucidate mechanisms underlying their biological variability. It is, however, frequently overlooked that also circumstances occurring after collection of biological samples can significantly affect the hormone concentrations measured, owing to analytical and pre-analytical variability. Whereas the awareness for such potential confounders is increasing in human laboratory medicine, there is sometimes limited consensus about the control of these factors in rodent studies. In this guide, we demonstrate how such factors can affect reliability and consequent interpretation of the data from immunoassay measurements of circulating metabolic hormones in rodent studies. We also compare the knowledge about such factors in rodent studies to recent recommendations established for biomarker studies in humans and give specific practical recommendations for the control of pre-analytical conditions in metabolic studies in rodents. PMID:24024118

Functional Analysis of Problem Behavior: A Systematic Approach for Identifying Idiosyncratic Variables

PubMed Central

Roscoe, Eileen M.; Schlichenmeyer, Kevin J.; Dube, William V.

2015-01-01

When inconclusive functional analysis (FA) outcomes occur, a number of modifications have been made to enhance the putative establishing operation or consequence associated with behavioral maintenance. However, a systematic method for identifying relevant events to test during modified FAs has not been evaluated. The purpose of this study was to develop and evaluate a technology for systematically identifying events to test in a modified FA after an initial FA led to inconclusive outcomes. Six individuals whose initial FA showed little or no responding or high levels only in the control condition participated. An indirect assessment (IA) questionnaire developed for identifying idiosyncratic variables was administered, and a descriptive analysis (DA) was conducted. Results from the IA only or a combination of the IA and DA were used to inform modified FA test and control conditions. Conclusive FA outcomes were obtained with five of the six participants during the modified FA phase. PMID:25930176

Gonadotropin level abnormalities in women with cyclic mastalgia.

PubMed

Ecochard, R; Marret, H; Rabilloud, M; Boehringer, H; Mathieu, C; Guerin, J F

2001-01-01

Women with cyclic mastalgia seem to be at risk of fibrocystic breast disease and/or breast cancer. We studied the relationships between mastalgia and hormone levels throughout the menstrual cycle. Ostensibly healthy women were monitored during a sum of 326 cycles. A case-control study compared personal and hormonal variables of 30 women experiencing cyclic mastalgia with those of 77 women without this symptom. Except sleeping times, no significant differences were found in personal variables. Cyclic mastalgia and symptoms of fluid retention were slightly associated. Menses and the luteal phase were significantly longer in cases than in controls. Gonadotropin but not ovarian hormone levels were also significantly higher in cases throughout the cycle. Cyclic mastalgia is less related to symptoms of fluid retention or to ovarian hormone levels than to regularly high gonadotropin levels, specific inhibitors might thus be used to alleviate the symptom.

Quality Control Methodology Of A Surface Wind Observational Database In North Eastern North America

NASA Astrophysics Data System (ADS)

Lucio-Eceiza, Etor E.; Fidel González-Rouco, J.; Navarro, Jorge; Conte, Jorge; Beltrami, Hugo

2016-04-01

This work summarizes the design and application of a Quality Control (QC) procedure for an observational surface wind database located in North Eastern North America. The database consists of 526 sites (486 land stations and 40 buoys) with varying resolutions of hourly, 3 hourly and 6 hourly data, compiled from three different source institutions with uneven measurement units and changing measuring procedures, instrumentation and heights. The records span from 1953 to 2010. The QC process is composed of different phases focused either on problems related with the providing source institutions or measurement errors. The first phases deal with problems often related with data recording and management: (1) compilation stage dealing with the detection of typographical errors, decoding problems, site displacements and unification of institutional practices; (2) detection of erroneous data sequence duplications within a station or among different ones; (3) detection of errors related with physically unrealistic data measurements. The last phases are focused on instrumental errors: (4) problems related with low variability, placing particular emphasis on the detection of unrealistic low wind speed records with the help of regional references; (5) high variability related erroneous records; (6) standardization of wind speed record biases due to changing measurement heights, detection of wind speed biases on week to monthly timescales, and homogenization of wind direction records. As a result, around 1.7% of wind speed records and 0.4% of wind direction records have been deleted, making a combined total of 1.9% of removed records. Additionally, around 15.9% wind speed records and 2.4% of wind direction data have been also corrected.

Effects of in-sewer processes: a stochastic model approach.

PubMed

Vollertsen, J; Nielsen, A H; Yang, W; Hvitved-Jacobsen, T

2005-01-01

Transformations of organic matter, nitrogen and sulfur in sewers can be simulated taking into account the relevant transformation and transport processes. One objective of such simulation is the assessment and management of hydrogen sulfide formation and corrosion. Sulfide is formed in the biofilms and sediments of the water phase, but corrosion occurs on the moist surfaces of the sewer gas phase. Consequently, both phases and the transport of volatile substances between these phases must be included. Furthermore, wastewater composition and transformations in sewers are complex and subject to high, natural variability. This paper presents the latest developments of the WATS model concept, allowing integrated aerobic, anoxic and anaerobic simulation of the water phase and of gas phase processes. The resulting model is complex and with high parameter variability. An example applying stochastic modeling shows how this complexity and variability can be taken into account.

Determinants and impact of suboptimal asthma control in Europe: The INTERNATIONAL CROSS-SECTIONAL AND LONGITUDINAL ASSESSMENT ON ASTHMA CONTROL (LIAISON) study.

PubMed

Braido, Fulvio; Brusselle, Guy; Guastalla, Daniele; Ingrassia, Eleonora; Nicolini, Gabriele; Price, David; Roche, Nicolas; Soriano, Joan B; Worth, Heinrich

2016-05-14

According to the Global Initiative of Asthma, the aim of asthma treatment is to gain and maintain control. In the INTERNATIONAL CROSS-SECTIONAL AND LONGITUDINAL ASSESSMENT ON ASTHMA CONTROL (LIAISON) study, we evaluated the level of asthma control and quality of life (QoL), as well as their determinants and impact in a population consulting specialist settings. LIAISON is a prospective, multicentre, observational study with a cross-sectional and a 12-month longitudinal phase. Adults with an asthma diagnosis since at least 6 months, receiving the same asthma treatment in the 4 weeks before enrolment were included. Asthma control was assessed with the 6-item Asthma Control Questionnaire (ACQ) and QoL with the MiniAsthma Quality of Life Questionnaire (MiniAQLQ). Overall, 8111 asthmatic patients were enrolled in 12 European countries. Asthma control was suboptimal in 56.5 % of patients and it was associated with poorer asthma-related QoL, higher risk of exacerbations and greater consumption of healthcare resources. Variables associated with suboptimal control were age, gender, obesity, smoking and comorbidities. Major determinants of poor asthma control were seasonal worsening and persisting exposure to allergens/irritants/triggers, followed by treatment-related issues. The cross-sectional phase results confirm that suboptimal control is frequent and has a high individual and economic impact. The clinicaltrials.gov identifier is NCT01567280 .

Quantifying Intrinsic Variability of Sagittarius A* Using Closure Phase Measurements of the Event Horizon Telescope

NASA Astrophysics Data System (ADS)

Roelofs, Freek; Johnson, Michael D.; Shiokawa, Hotaka; Doeleman, Sheperd S.; Falcke, Heino

2017-09-01

General relativistic magnetohydrodynamic (GRMHD) simulations of accretion disks and jets associated with supermassive black holes show variability on a wide range of timescales. On timescales comparable to or longer than the gravitational timescale {t}G={GM}/{c}3, variation may be dominated by orbital dynamics of the inhomogeneous accretion flow. Turbulent evolution within the accretion disk is expected on timescales comparable to the orbital period, typically an order of magnitude larger than t G . For Sgr A*, t G is much shorter than the typical duration of a VLBI experiment, enabling us to study this variability within a single observation. Closure phases, the sum of interferometric visibility phases on a triangle of baselines, are particularly useful for studying this variability. In addition to a changing source structure, variations in observed closure phase can also be due to interstellar scattering, thermal noise, and the changing geometry of projected baselines over time due to Earth rotation. We present a metric that is able to distinguish the latter two from intrinsic or scattering variability. This metric is validated using synthetic observations of GRMHD simulations of Sgr A*. When applied to existing multi-epoch EHT data of Sgr A*, this metric shows that the data are most consistent with source models containing intrinsic variability from source dynamics, interstellar scattering, or a combination of those. The effects of black hole inclination, orientation, spin, and morphology (disk or jet) on the expected closure phase variability are also discussed.

Boltzmann sampling for an XY model using a non-degenerate optical parametric oscillator network

NASA Astrophysics Data System (ADS)

Takeda, Y.; Tamate, S.; Yamamoto, Y.; Takesue, H.; Inagaki, T.; Utsunomiya, S.

2018-01-01

We present an experimental scheme of implementing multiple spins in a classical XY model using a non-degenerate optical parametric oscillator (NOPO) network. We built an NOPO network to simulate a one-dimensional XY Hamiltonian with 5000 spins and externally controllable effective temperatures. The XY spin variables in our scheme are mapped onto the phases of multiple NOPO pulses in a single ring cavity and interactions between XY spins are implemented by mutual injections between NOPOs. We show the steady-state distribution of optical phases of such NOPO pulses is equivalent to the Boltzmann distribution of the corresponding XY model. Estimated effective temperatures converged to the setting values, and the estimated temperatures and the mean energy exhibited good agreement with the numerical simulations of the Langevin dynamics of NOPO phases.

Portable system for temperature monitoring in all phases of wine production.

PubMed

Boquete, Luciano; Cambralla, Rafael; Rodríguez-Ascariz, J M; Miguel-Jiménez, J M; Cantos-Frontela, J J; Dongil, J

2010-07-01

This paper presents a low-cost and highly versatile temperature-monitoring system applicable to all phases of wine production, from grape cultivation through to delivery of bottled wine to the end customer. Monitoring is performed by a purpose-built electronic system comprising a digital memory that stores temperature data and a ZigBee communication system that transmits it to a Control Centre for processing and display. The system has been tested under laboratory conditions and in real-world operational applications. One of the system's advantages is that it can be applied to every phase of wine production. Moreover, with minimum modification, other variables of interest (pH, humidity, etc.) could also be monitored and the system could be applied to other similar sectors, such as olive-oil production. 2010 ISA. Published by Elsevier Ltd. All rights reserved.

Retrospective Cost Adaptive Control with Concurrent Closed-Loop Identification

NASA Astrophysics Data System (ADS)

Sobolic, Frantisek M.

Retrospective cost adaptive control (RCAC) is a discrete-time direct adaptive control algorithm for stabilization, command following, and disturbance rejection. RCAC is known to work on systems given minimal modeling information which is the leading numerator coefficient and any nonminimum-phase (NMP) zeros of the plant transfer function. This information is normally needed a priori and is key in the development of the filter, also known as the target model, within the retrospective performance variable. A novel approach to alleviate the need for prior modeling of both the leading coefficient of the plant transfer function as well as any NMP zeros is developed. The extension to the RCAC algorithm is the use of concurrent optimization of both the target model and the controller coefficients. Concurrent optimization of the target model and controller coefficients is a quadratic optimization problem in the target model and controller coefficients separately. However, this optimization problem is not convex as a joint function of both variables, and therefore nonconvex optimization methods are needed. Finally, insights within RCAC that include intercalated injection between the controller numerator and the denominator, unveil the workings of RCAC fitting a specific closed-loop transfer function to the target model. We exploit this interpretation by investigating several closed-loop identification architectures in order to extract this information for use in the target model.

Randomized controlled dissemination study of community-to-clinic navigation to promote CRC screening: Study design and implications.

PubMed

Larkey, Linda; Szalacha, Laura; Herman, Patricia; Gonzalez, Julie; Menon, Usha

2017-02-01

Regular screening facilitates early diagnosis of colorectal cancer (CRC) and reduction of CRC morbidity and mortality. Screening rates for minorities and low-income populations remain suboptimal. Provider referral for CRC screening is one of the strongest predictors of adherence, but referrals are unlikely among those who have no clinic home (common among poor and minority populations). This group randomized controlled study will test the effectiveness of an evidence based tailored messaging intervention in a community-to-clinic navigation context compared to no navigation. Multicultural, underinsured individuals from community sites will be randomized (by site) to receive CRC screening education only, or education plus navigation. In Phase I, those randomized to education plus navigation will be guided to make a clinic appointment to receive a provider referral for CRC screening. Patients attending clinic appointments will continue to receive navigation until screened (Phase II) regardless of initial arm assignment. We hypothesize that those receiving education plus navigation will be more likely to attend clinic appointments (H1) and show higher rates of screening (H2) compared to those receiving education only. Phase I group assignment will be used as a control variable in analysis of screening follow-through in Phase II. Costs per screening achieved will be evaluated for each condition and the RE-AIM framework will be used to examine dissemination results. The novelty of our study design is the translational dissemination model that will allow us to assess the real-world application of an efficacious intervention previously tested in a randomized controlled trial. Copyright © 2016. Published by Elsevier Inc.

Mechanism of blood pressure and R-R variability: insights from ganglion blockade in humans

NASA Technical Reports Server (NTRS)

Zhang, Rong; Iwasaki, Kenichi; Zuckerman, Julie H.; Behbehani, Khosrow; Crandall, Craig G.; Levine, Benjamin D.; Blomqvist, C. G. (Principal Investigator)

2002-01-01

Spontaneous blood pressure (BP) and R-R variability are used frequently as 'windows' into cardiovascular control mechanisms. However, the origin of these rhythmic fluctuations is not completely understood. In this study, with ganglion blockade, we evaluated the role of autonomic neural activity versus other 'non-neural' factors in the origin of BP and R-R variability in humans. Beat-to-beat BP, R-R interval and respiratory excursions were recorded in ten healthy subjects (aged 30 +/- 6 years) before and after ganglion blockade with trimethaphan. The spectral power of these variables was calculated in the very low (0.0078-0.05 Hz), low (0.05-0.15 Hz) and high (0.15-0.35 Hz) frequency ranges. The relationship between systolic BP and R-R variability was examined by cross-spectral analysis. After blockade, R-R variability was virtually abolished at all frequencies; however, respiration and high frequency BP variability remained unchanged. Very low and low frequency BP variability was reduced substantially by 84 and 69 %, respectively, but still persisted. Transfer function gain between systolic BP and R-R interval variability decreased by 92 and 88 % at low and high frequencies, respectively, while the phase changed from negative to positive values at the high frequencies. These data suggest that under supine resting conditions with spontaneous breathing: (1) R-R variability at all measured frequencies is predominantly controlled by autonomic neural activity; (2) BP variability at high frequencies (> 0.15 Hz) is mediated largely, if not exclusively, by mechanical effects of respiration on intrathoracic pressure and/or cardiac filling; (3) BP variability at very low and low frequencies (< 0.15 Hz) is probably mediated by both sympathetic nerve activity and intrinsic vasomotor rhythmicity; and (4) the dynamic relationship between BP and R-R variability as quantified by transfer function analysis is determined predominantly by autonomic neural activity rather than other, non-neural factors.

Ergodicity of a singly-thermostated harmonic oscillator

NASA Astrophysics Data System (ADS)

Hoover, William Graham; Sprott, Julien Clinton; Hoover, Carol Griswold

2016-03-01

Although Nosé's thermostated mechanics is formally consistent with Gibbs' canonical ensemble, the thermostated Nosé-Hoover (harmonic) oscillator, with its mean kinetic temperature controlled, is far from ergodic. Much of its phase space is occupied by regular conservative tori. Oscillator ergodicity has previously been achieved by controlling two oscillator moments with two thermostat variables. Here we use computerized searches in conjunction with visualization to find singly-thermostated motion equations for the oscillator which are consistent with Gibbs' canonical distribution. Such models are the simplest able to bridge the gap between Gibbs' statistical ensembles and Newtonian single-particle dynamics.

Stressed Oxidation Life Prediction for C/SiC Composites

NASA Technical Reports Server (NTRS)

Levine, Stanley R.

2004-01-01

The residual strength and life of C/SiC is dominated by carbon interface and fiber oxidation if seal coat and matrix cracks are open to allow oxygen ingress. Crack opening is determined by the combination of thermal, mechanical and thermal expansion mismatch induced stresses. When cracks are open, life can be predicted by simple oxidation based models with reaction controlled kinetics at low temperature, and by gas phase diffusion controlled kinetics at high temperatures. Key life governing variables in these models include temperature, stress, initial strength, oxygen partial pressure, and total pressure. These models are described in this paper.

Psychosocial Profile of Women with Premenstrual Syndrome and Healthy Controls: A Comparative Study.

PubMed

Kleinstäuber, Maria; Schmelzer, Katarina; Ditzen, Beate; Andersson, Gerhard; Hiller, Wolfgang; Weise, Cornelia

2016-12-01

According to modern bio-psychosocial theories of premenstrual syndrome (PMS), the aim of this study is to investigate systematically associations between selected psychosocial factors and premenstrual symptoms in different menstrual cycle phases. Several psychosocial variables were assessed, in a sample of German women with PMS (N = 90) and without premenstrual complaints (N = 48) during the follicular and luteal phase of the menstrual cycle. Presence of PMS was indicated by analysis of contemporary daily ratings of premenstrual symptom severity and impairment for one menstrual cycle. Regarding perceived chronic stress (ƞ 2  = 0.34), self-efficacy (ƞ 2  = 0.12), and two dimensions of self-silencing (0.06 ≤ ƞ 2  ≤ 0.11) analyses revealed only a significant effect of group. Regarding body dissatisfaction and somatosensory amplification, a significant effect of group (0.07 ≤ ƞ 2  ≤ 0.16) and additionally a group by menstrual cycle phase interaction (ƞ 2  = 0.06) was identified. Regarding relationship quality, a significant effect of menstrual cycle phase (ƞ 2  = 0.08) and a group by menstrual cycle phase interaction (ƞ 2  = 0.06) was demonstrated. In respect to sexual contentment, acceptance of premenstrual symptoms, and the remaining two dimensions of self-silencing statistical analyses revealed no effects at all. Linear multiple regression analysis revealed that 20 % of the variance in PMS symptom severity was explained by the psychosocial variables investigated. Body dissatisfaction (ß = 0.26, p = 0.018) and the divided self-dimension of self-silencing (ß = 0.35, p = 0.016) were significant correlates of PMS severity. Results of this study are consistent with previous research and additionally show patterns of associations between specific psychosocial factors and PMS in dependence of menstrual cycle phase that have not been researched before. The role of the psychosocial variables we investigated in regard to the development and maintenance of PMS should be clarified in future research.

Terminal spacecraft rendezvous and capture with LASSO model predictive control

NASA Astrophysics Data System (ADS)

Hartley, Edward N.; Gallieri, Marco; Maciejowski, Jan M.

2013-11-01

The recently investigated ℓasso model predictive control (MPC) is applied to the terminal phase of a spacecraft rendezvous and capture mission. The interaction between the cost function and the treatment of minimum impulse bit is also investigated. The propellant consumption with ℓasso MPC for the considered scenario is noticeably less than with a conventional quadratic cost and control actions are sparser in time. Propellant consumption and sparsity are competitive with those achieved using a zone-based ℓ1 cost function, whilst requiring fewer decision variables in the optimisation problem than the latter. The ℓasso MPC is demonstrated to meet tighter specifications on control precision and also avoids the risk of undesirable behaviours often associated with pure ℓ1 stage costs.

On the adaptive sliding mode controller for a hyperchaotic fractional-order financial system

NASA Astrophysics Data System (ADS)

Hajipour, Ahamad; Hajipour, Mojtaba; Baleanu, Dumitru

2018-05-01

This manuscript mainly focuses on the construction, dynamic analysis and control of a new fractional-order financial system. The basic dynamical behaviors of the proposed system are studied such as the equilibrium points and their stability, Lyapunov exponents, bifurcation diagrams, phase portraits of state variables and the intervals of system parameters. It is shown that the system exhibits hyperchaotic behavior for a number of system parameters and fractional-order values. To stabilize the proposed hyperchaotic fractional system with uncertain dynamics and disturbances, an efficient adaptive sliding mode controller technique is developed. Using the proposed technique, two hyperchaotic fractional-order financial systems are also synchronized. Numerical simulations are presented to verify the successful performance of the designed controllers.

Thin Film Synthesis of New Complex Titanates.

NASA Astrophysics Data System (ADS)

Salvador, Paul

2008-03-01

Thin film deposition methods allow for one to synthesize rationally specific compositions in targeted crystal structures. Because most of the thermodynamic and kinetic variables that control the range of materials that can be synthesized are unknown for specific compounds/processes, epitaxial stabilization and design of artificially layered crystals are driven through empirical investigations. Using examples taken primarily from the family of complex titanates, which exhibit a range of interesting physicochemical behaviors, the thermodynamic and kinetic factors that control materials design using thin film deposition are discussed. The phase competition between the pyrochlore and the (110) layered perovskite structure in the RE2Ti2O7 family (RE = rare-earth, Bi) will be explored, using pulsed laser deposition as a synthesis method. For RE = Gd, Sm, Nd, and La, the phase stability over a wide range of conditions is dictated entirely by substrate choice, indicating that the free energies of the phases are similar enough such that by controlling nucleation one controls the phase formation. In a related fashion, the growth of AETi2O5 films (AE = Ba or Sr) will be discussed with respect to the formation of single-phase films or films that phase separate into AETiO3 and TiO2. The entire Ba1-xSrxTi2O5 series was grown and will be discussed with respect to growth technique (using MBE and PLD) and/or substrate choice. In this case, rock-salt substrates, which are not expected to interact strongly with any phase in the system, allow for the formation of single-phase films. Finally, several examples will be discussed with respect to the (SrO)m(TiO2)n system, which includes the perovskite SrTiO3 and the Ruddlesden-Popper phase Sr2TiO4, grown using layer-by-layer molecular beam epitaxy. The solid phase epitaxial formation of the perovskite SrTiO3 from superlattices of rock-salt SrO and anatase TiO2 is discussed from both a kinetic and thermodynamic perspective by exploring the growth of a range of m and n values. Using similar arguments for stability, new layered intergrowths in the SrmTiO2+m family are presented and their structures are discussed.

AC Resonant charger with charge rate unrelated to primary power frequency

DOEpatents

Watson, Harold

1982-01-01

An AC resonant charger for a capacitive load, such as a PFN, is provided with a variable repetition rate unrelated to the frequency of a multi-phase AC power source by using a control unit to select and couple the phase of the power source to the resonant charger in order to charge the capacitive load with a phase that is the next to begin a half cycle. For optimum range in repetition rate and increased charging voltage, the resonant charger includes a step-up transformer and full-wave rectifier. The next phase selected may then be of either polarity, but is always selected to be of a polarity opposite the polarity of the last phase selected so that the transformer core does not saturate. Thyristors are used to select and couple the correct phase just after its zero crossover in response to a sharp pulse generated by a zero-crossover detector. The thyristor that is turned on then automatically turns off after a full half cycle of its associated phase input. A full-wave rectifier couples the secondary winding of the transformer to the load so that the load capacitance is always charged with the same polarity.

Ac resonant charger with charge rate unrelated to preimary power requency

DOEpatents

Not Available

1979-12-07

An ac resonant charger for a capacitive load, such as a pulse forming network (PFN), is provided with a variable repetition rate unrelated to the frequency of a multi-phase ac power source by using a control unit to select and couple the phase of the power source to the resonant charger in order to charge the capacitive load with a phase that is the next to begin a half cycle. For optimum range in repetition rate and increased charging voltage, the resonant charger includes a step-up transformer and full-wave rectifier. The next phase selected may then be of either polarity, but is always selected to be of a polarity opposite the polarity of the last phase selected so that the transformer core does not saturate. Thyristors are used to select and couple the correct phase just after its zero crossover in response to a sharp pulse generated by a zero-crossover detector. The thyristor that is turned on then automatically turns off after a full half cycle of its associated phase input. A full-wave rectifier couples the secondary winding of the transformer to the load so that the load capacitance is always charged with the same polarity.

Speech production variability in fricatives of children and adults: Results of functional data analysis

PubMed Central

Koenig, Laura L.; Lucero, Jorge C.; Perlman, Elizabeth

2008-01-01

This study investigates token-to-token variability in fricative production of 5 year olds, 10 year olds, and adults. Previous studies have reported higher intrasubject variability in children than adults, in speech as well as nonspeech tasks, but authors have disagreed on the causes and implications of this finding. The current work assessed the characteristics of age-related variability across articulators (larynx and tongue) as well as in temporal versus spatial domains. Oral airflow signals, which reflect changes in both laryngeal and supralaryngeal apertures, were obtained for multiple productions of ∕h s z∕. The data were processed using functional data analysis, which provides a means of obtaining relatively independent indices of amplitude and temporal (phasing) variability. Consistent with past work, both temporal and amplitude variabilities were higher in children than adults, but the temporal indices were generally less adultlike than the amplitude indices for both groups of children. Quantitative and qualitative analyses showed considerable speaker- and consonant-specific patterns of variability. The data indicate that variability in ∕s∕ may represent laryngeal as well as supralaryngeal control and further that a simple random noise factor, higher in children than in adults, is insufficient to explain developmental differences in speech production variability. PMID:19045800

Method and apparatus for thermal management of vehicle exhaust systems

DOEpatents

Benson, D.K.; Potter, T.F.

1995-12-26

A catalytic converter is surrounded by variable conductance insulation for maintaining the operating temperature of the catalytic converter at an optimum level, for inhibiting heat loss when raising catalytic converter temperature to light-off temperature, for storing excess heat to maintain or accelerate reaching light-off temperature, and for conducting excess heat away from the catalytic converter after reaching light-off temperature. The variable conductance insulation includes vacuum gas control and metal-to-metal thermal shunt mechanisms. Radial and axial shielding inhibits radiation and convection heat loss. Thermal storage media includes phase change material, and heat exchanger chambers and fluids carry heat to and from the catalytic converter. 7 figs.

Enhancing vehicle cornering limit through sideslip and yaw rate control

NASA Astrophysics Data System (ADS)

Lu, Qian; Gentile, Pierangelo; Tota, Antonio; Sorniotti, Aldo; Gruber, Patrick; Costamagna, Fabio; De Smet, Jasper

2016-06-01

Fully electric vehicles with individually controlled drivetrains can provide a high degree of drivability and vehicle safety, all while increasing the cornering limit and the 'fun-to-drive' aspect. This paper investigates a new approach on how sideslip control can be integrated into a continuously active yaw rate controller to extend the limit of stable vehicle cornering and to allow sustained high values of sideslip angle. The controllability-related limitations of integrated yaw rate and sideslip control, together with its potential benefits, are discussed through the tools of multi-variable feedback control theory and non-linear phase-plane analysis. Two examples of integrated yaw rate and sideslip control systems are presented and their effectiveness is experimentally evaluated and demonstrated on a four-wheel-drive fully electric vehicle prototype. Results show that the integrated control system allows safe operation at the vehicle cornering limit at a specified sideslip angle independent of the tire-road friction conditions.

Intelligent Optical Systems Using Adaptive Optics

NASA Technical Reports Server (NTRS)

Clark, Natalie

2012-01-01

Until recently, the phrase adaptive optics generally conjured images of large deformable mirrors being integrated into telescopes to compensate for atmospheric turbulence. However, the development of smaller, cheaper devices has sparked interest for other aerospace and commercial applications. Variable focal length lenses, liquid crystal spatial light modulators, tunable filters, phase compensators, polarization compensation, and deformable mirrors are becoming increasingly useful for other imaging applications including guidance navigation and control (GNC), coronagraphs, foveated imaging, situational awareness, autonomous rendezvous and docking, non-mechanical zoom, phase diversity, and enhanced multi-spectral imaging. The active components presented here allow flexibility in the optical design, increasing performance. In addition, the intelligent optical systems presented offer advantages in size and weight and radiation tolerance.

Variability of western Amazon dry-season precipitation extremes: importance of decadal fluctuations and implications for predictability

NASA Astrophysics Data System (ADS)

Fernandes, K.; Baethgen, W.; Verchot, L. V.; Giannini, A.; Pinedo-Vasquez, M.

2014-12-01

A complete assessment of climate change projections requires understanding the combined effects of decadal variability and long-term trends and evaluating the ability of models to simulate them. The western Amazon severe droughts of the 2000s were the result of a modest drying trend enhanced by reduced moisture transport from the tropical Atlantic. Most of the WA dry-season precipitation decadal variability is attributable to decadal fluctuations of the north-south gradient (NSG) in Atlantic sea surface temperature (SST). The observed WA and NSG decadal co-variability is well reproduced in Global Climate Models (GCMs) pre-industrial control (PIC) and historical (HIST) experiments that were part of the Intergovernmental Panel on Climate Change fifth assessment report (IPCC-AR5). This suggests that unforced or natural climate variability, characteristic of the PIC simulations, determines the nature of this coupling, as the results from HIST simulations (forced with greenhouse gases (GHG) and natural and anthropogenic aerosols) are comparable in magnitude and spatial distribution. Decadal fluctuation in the NSG also determines shifts in the probability of repeated droughts and pluvials in WA, as there is a 65% chance of 3 or more years of droughts per decade when NSG>0 compared to 18% when NSG<0. The HIST and PIC model simulations also reproduce the observed shifts in probability distribution of droughts and pluvials as a function of the NSG decadal phase, suggesting there is great potential for decadal predictability based on GCMs. Persistence of the current NSG positive phase may lead to continuing above normal frequencies of western Amazon dry-season droughts.

Quantitative model of transport-aperture coordination during reach-to-grasp movements.

PubMed

Rand, Miya K; Shimansky, Y P; Hossain, Abul B M I; Stelmach, George E

2008-06-01

It has been found in our previous studies that the initiation of aperture closure during reach-to-grasp movements occurs when the hand distance to target crosses a threshold that is a function of peak aperture amplitude, hand velocity, and hand acceleration. Thus, a stable relationship between those four movement parameters is observed at the moment of aperture closure initiation. Based on the concept of optimal control of movements (Naslin 1969) and its application for reach-to-grasp movement regulation (Hoff and Arbib 1993), it was hypothesized that the mathematical equation expressing that relationship can be generalized to describe coordination between hand transport and finger aperture during the entire reach-to-grasp movement by adding aperture velocity and acceleration to the above four movement parameters. The present study examines whether this hypothesis is supported by the data obtained in experiments in which young adults performed reach-to-grasp movements in eight combinations of two reach-amplitude conditions and four movement-speed conditions. It was found that linear approximation of the mathematical model described the relationship among the six movement parameters for the entire aperture-closure phase with very high precision for each condition, thus supporting the hypothesis for that phase. Testing whether one mathematical model could approximate the data across all the experimental conditions revealed that it was possible to achieve the same high level of data-fitting precision only by including in the model two additional, condition-encoding parameters and using a nonlinear, artificial neural network-based approximator with two hidden layers comprising three and two neurons, respectively. This result indicates that transport-aperture coordination, as a specific relationship between the parameters of hand transport and finger aperture, significantly depends on the condition-encoding variables. The data from the aperture-opening phase also fit a linear model, whose coefficients were substantially different from those identified for the aperture-closure phase. This result supports the above hypothesis for the aperture-opening phase, and consequently, for the entire reach-to-grasp movement. However, the fitting precision was considerably lower than that for the aperture-closure phase, indicating significant trial-to-trial variability of transport-aperture coordination during the aperture-opening phase. Implications for understanding the neural mechanisms employed by the CNS for controlling reach-to-grasp movements and utilization of the mathematical model of transport-aperture coordination for data analysis are discussed.

Components of day-to-day variability of cerebral perfusion measurements - Analysis of phase contrast mapping magnetic resonance imaging measurements in healthy volunteers.

PubMed

Ismaili, Abd R A; Vestergaard, Mark B; Hansen, Adam E; Larsson, Henrik B W; Johannesen, Helle H; Law, Ian; Henriksen, Otto M

2018-01-01

The aim of the study was to investigate the components of day-to-day variability of repeated phase contrast mapping (PCM) magnetic resonance imaging measurements of global cerebral blood flow (gCBF). Two dataset were analyzed. In Dataset 1 duplicated PCM measurements of total brain flow were performed in 11 healthy young volunteers on two separate days applying a strictly standardized setup. For comparison PCM measurements obtained from a previously published study (Dataset 2) were analyzed in order to assess long-term variability in an aged population in a less strictly controlled setup. Global CBF was calculated by normalizing total brain flow to brain volume. On each day measurements of hemoglobin, caffeine and glucose were obtained. Linear mixed models were applied to estimate coefficients of variation (CV) of total (CVt), between-subject (CVb), within-subject day-to-day (CVw), and intra-session residual variability (CVr). In Dataset 1 CVt, CVb, CVw and CVr were estimated to be 11%, 9.4%, 4% and 4.2%, respectively, and to 8.8%, 7.2%, 2.7% and 4.3%, respectively, when adjusting for hemoglobin and plasma caffeine. In Dataset 2 CVt, CVb and CVw were estimated to be 25.4%, 19.2%, and 15.0%, respectively, and decreased to 16.6%, 8.2% and 12.5%, respectively, when adjusting for the same covariates. Our results suggest that short-term day-to-day variability of gCBF is relatively low compared to between-subject variability when studied in standardized conditions, whereas long-term variability in an aged population appears to be much larger when studied in less a standardized setup. The results further showed that from 20% to 35% of the total variability in gCBF can be attributed to the effects of hemoglobin and caffeine.

Operation and Maintenance Manual, TECS 18.

DTIC Science & Technology

1978-11-01

width modulated variable output voltage and frequency using a three-phase transistor bridge circuit . Reduced power line electromagnetic interference...Description 3-1 Section II. Circuit Fundamentals 3-1 Section III. System Description 3-2 CHAPTER 4. Protection and Maintenance 4-1 Section I. Internal...Number I-la TECS 18 Electronic Module Location-Evaporator Side 1-3 1-lb TECS 18 Electronic Module Location-Condenser Side 1-4 1-2 Remote Control Panel 1-5

Impact of Forecast and Model Error Correlations In 4dvar Data Assimilation

NASA Astrophysics Data System (ADS)

Zupanski, M.; Zupanski, D.; Vukicevic, T.; Greenwald, T.; Eis, K.; Vonder Haar, T.

A weak-constraint 4DVAR data assimilation system has been developed at Cooper- ative Institute for Research in the Atmosphere (CIRA), Colorado State University. It is based on the NCEP's ETA 4DVAR system, and it is fully parallel (MPI coding). The CIRA's 4DVAR system is aimed for satellite data assimilation research, with cur- rent focus on assimilation of cloudy radiances and microwave satellite measurements. Most important improvement over the previous 4DVAR system is a degree of gener- ality introduced into the new algorithm, namely for applications with different NWP models (e.g., RAMS, WRF, ETA, etc.), and for the choice of control variable. In cur- rent applications, the non-hydrostatic RAMS model and its adjoint are used, including all microphysical processess. The control variable includes potential temperature, ve- locity potential and stream function, vertical velocity, and seven mixing ratios with respect to all water phases. Since the statistics of the microphysical components of the control variable is not well known, a special attention will be paid to the impact of the forecast and model (prior) error correlations on the 4DVAR analysis. In particular, the sensitivity of the analysis with respect to decorrelation length will be examined. The prior error covariances are modelled using the compactly-supported, space-limited correlations developed at NASA DAO.

Thermal design and test of a high power spacecraft transponder platform

NASA Technical Reports Server (NTRS)

Stipandic, E. A.; Gray, A. M.; Gedeon, L.

1975-01-01

The high power transponder subsystem on board the Communications Technology Satellite (CTS) requires some unique thermal control techniques to maintain the required temperature limits throughout all mission phases. The transponder subsystem includes redundant 20-W output travelling wave tubes and a single 200-W output TWT with highly concentrated thermal dissipations of 70 W and 143 W, respectively. A thermal control system which maintains all components within the required temperature ranges has been designed and verified in thermal balance testing. Included in the design are second surface quartz mirrors on an aluminum honeycomb platform, high thermal conductivity aluminum doubler plates, commandable thermal control heaters and a Variable Conductance Heat Pipe System (VCHPS).

Variable Sampling Mapping

NASA Technical Reports Server (NTRS)

Smith, Jeffrey, S.; Aronstein, David L.; Dean, Bruce H.; Lyon, Richard G.

2012-01-01

The performance of an optical system (for example, a telescope) is limited by the misalignments and manufacturing imperfections of the optical elements in the system. The impact of these misalignments and imperfections can be quantified by the phase variations imparted on light traveling through the system. Phase retrieval is a methodology for determining these variations. Phase retrieval uses images taken with the optical system and using a light source of known shape and characteristics. Unlike interferometric methods, which require an optical reference for comparison, and unlike Shack-Hartmann wavefront sensors that require special optical hardware at the optical system's exit pupil, phase retrieval is an in situ, image-based method for determining the phase variations of light at the system s exit pupil. Phase retrieval can be used both as an optical metrology tool (during fabrication of optical surfaces and assembly of optical systems) and as a sensor used in active, closed-loop control of an optical system, to optimize performance. One class of phase-retrieval algorithms is the iterative transform algorithm (ITA). ITAs estimate the phase variations by iteratively enforcing known constraints in the exit pupil and at the detector, determined from modeled or measured data. The Variable Sampling Mapping (VSM) technique is a new method for enforcing these constraints in ITAs. VSM is an open framework for addressing a wide range of issues that have previously been considered detrimental to high-accuracy phase retrieval, including undersampled images, broadband illumination, images taken at or near best focus, chromatic aberrations, jitter or vibration of the optical system or detector, and dead or noisy detector pixels. The VSM is a model-to-data mapping procedure. In VSM, fully sampled electric fields at multiple wavelengths are modeled inside the phase-retrieval algorithm, and then these fields are mapped to intensities on the light detector, using the properties of the detector and optical system, for comparison with measured data. Ultimately, this model-to-data mapping procedure enables a more robust and accurate way of incorporating the exit-pupil and image detector constraints, which are fundamental to the general class of ITA phase retrieval algorithms.

Increased Intra-Participant Variability in Children with Autistic Spectrum Disorders: Evidence from Single-Trial Analysis of Evoked EEG

PubMed Central

Milne, Elizabeth

2011-01-01

Intra-participant variability in clinical conditions such as autistic spectrum disorder (ASD) is an important indicator of pathophysiological processing. The data reported here illustrate that trial-by-trial variability can be reliably measured from EEG, and that intra-participant EEG variability is significantly greater in those with ASD than in neuro-typical matched controls. EEG recorded at the scalp is a linear mixture of activity arising from muscle artifacts and numerous concurrent brain processes. To minimize these additional sources of variability, EEG data were subjected to two different methods of spatial filtering. (i) The data were decomposed using infomax independent component analysis, a method of blind source separation which un-mixes the EEG signal into components with maximally independent time-courses, and (ii) a surface Laplacian transform was performed (current source density interpolation) in order to reduce the effects of volume conduction. Data are presented from 13 high functioning adolescents with ASD without co-morbid ADHD, and 12 neuro-typical age-, IQ-, and gender-matched controls. Comparison of variability between the ASD and neuro-typical groups indicated that intra-participant variability of P1 latency and P1 amplitude was greater in the participants with ASD, and inter-trial α-band phase coherence was lower in the participants with ASD. These data support the suggestion that individuals with ASD are less able to synchronize the activity of stimulus-related cell assemblies than neuro-typical individuals, and provide empirical evidence in support of theories of increased neural noise in ASD. PMID:21716921

New approaches for sampling and modeling native and exotic plant species richness

USGS Publications Warehouse

Chong, G.W.; Reich, R.M.; Kalkhan, M.A.; Stohlgren, T.J.

2001-01-01

We demonstrate new multi-phase, multi-scale approaches for sampling and modeling native and exotic plant species to predict the spread of invasive species and aid in control efforts. Our test site is a 54,000-ha portion of Rocky Mountain National Park, Colorado, USA. This work is based on previous research wherein we developed vegetation sampling techniques to identify hot spots of diversity, important rare habitats, and locations of invasive plant species. Here we demonstrate statistical modeling tools to rapidly assess current patterns of native and exotic plant species to determine which habitats are most vulnerable to invasion by exotic species. We use stepwise multiple regression and modified residual kriging to estimate numbers of native species and exotic species, as well as probability of observing an exotic species in 30 × 30-m cells. Final models accounted for 62% of the variability observed in number of native species, 51% of the variability observed in number of exotic species, and 47% of the variability associated with observing an exotic species. Important independent variables used in developing the models include geographical location, elevation, slope, aspect, and Landsat TM bands 1-7. These models can direct resource managers to areas in need of further inventory, monitoring, and exotic species control efforts.

Decadal variability of tropical tropopause temperature and its relationship to the Pacific Decadal Oscillation.

PubMed

Wang, Wuke; Matthes, Katja; Omrani, Nour-Eddine; Latif, Mojib

2016-07-12

Tropopause temperatures (TPTs) control the amount of stratospheric water vapour, which influences chemistry, radiation and circulation in the stratosphere, and is also an important driver of surface climate. Decadal variability and long-term trends in tropical TPTs as well as stratospheric water vapour are largely unknown. Here, we present for the first time evidence, from reanalysis and state-of-the-art climate model simulations, of a link between decadal variability in tropical TPTs and the Pacific Decadal Oscillation (PDO). The negative phase of the PDO is associated with anomalously cold sea surface temperatures (SSTs) in the tropical east and central Pacific, which enhance the zonal SST gradient across the equatorial Pacific. The latter drives a stronger Walker Circulation and a weaker Hadley Circulation, which leads to less convection and subsequently a warmer tropopause over the central equatorial Pacific. Over the North Pacific, positive sea level pressure anomalies occur, which damp vertical wave propagation into the stratosphere. This in turn slows the Brewer-Dobson circulation, and hence warms the tropical tropopause, enabling more water vapour to enter the stratosphere. The reverse chain of events holds for the positive phase of the PDO. Such ocean-troposphere-stratosphere interactions may provide an important feedback on the Earth's global surface temperature.

Decadal variability of tropical tropopause temperature and its relationship to the Pacific Decadal Oscillation

PubMed Central

Wang, Wuke; Matthes, Katja; Omrani, Nour-Eddine; Latif, Mojib

2016-01-01

Tropopause temperatures (TPTs) control the amount of stratospheric water vapour, which influences chemistry, radiation and circulation in the stratosphere, and is also an important driver of surface climate. Decadal variability and long-term trends in tropical TPTs as well as stratospheric water vapour are largely unknown. Here, we present for the first time evidence, from reanalysis and state-of-the-art climate model simulations, of a link between decadal variability in tropical TPTs and the Pacific Decadal Oscillation (PDO). The negative phase of the PDO is associated with anomalously cold sea surface temperatures (SSTs) in the tropical east and central Pacific, which enhance the zonal SST gradient across the equatorial Pacific. The latter drives a stronger Walker Circulation and a weaker Hadley Circulation, which leads to less convection and subsequently a warmer tropopause over the central equatorial Pacific. Over the North Pacific, positive sea level pressure anomalies occur, which damp vertical wave propagation into the stratosphere. This in turn slows the Brewer-Dobson circulation, and hence warms the tropical tropopause, enabling more water vapour to enter the stratosphere. The reverse chain of events holds for the positive phase of the PDO. Such ocean-troposphere-stratosphere interactions may provide an important feedback on the Earth’s global surface temperature. PMID:27404090

Eastern South African hydroclimate over the past 270,000 years

NASA Astrophysics Data System (ADS)

Simon, Margit H.; Ziegler, Martin; Bosmans, Joyce; Barker, Stephen; Reason, Chris J. C.; Hall, Ian R.

2015-12-01

Processes that control the hydrological balance in eastern South Africa on orbital to millennial timescales remain poorly understood because proxy records documenting its variability at high resolution are scarce. In this work, we present a detailed 270,000 year-long record of terrestrial climate variability in the KwaZulu-Natal province based on elemental ratios of Fe/K from the southwest Indian Ocean, derived from X-ray fluorescence core scanning. Eastern South African climate variability on these time scales reflects both the long-term effect of regional insolation changes driven by orbital precession and the effects associated with high-latitude abrupt climate forcing over the past two glacial-interglacial cycles, including millennial-scale events not previously identified. Rapid changes towards more humid conditions in eastern South Africa as the Northern Hemisphere entered phases of extreme cooling were potentially driven by a combination of warming in the Agulhas Current and shifts of the subtropical anticyclones. These climate oscillations appear coherent with other Southern Hemisphere records but are anti-phased with respect to the East Asian Monsoon. Numerical modelling results reveal that higher precipitation in the KwaZulu-Natal province during precession maxima is driven by a combination of increased local evaporation and elevated moisture transport into eastern South Africa from the coast of Mozambique.

Eastern South African hydroclimate over the past 270,000 years.

PubMed

Simon, Margit H; Ziegler, Martin; Bosmans, Joyce; Barker, Stephen; Reason, Chris J C; Hall, Ian R

2015-12-21

Processes that control the hydrological balance in eastern South Africa on orbital to millennial timescales remain poorly understood because proxy records documenting its variability at high resolution are scarce. In this work, we present a detailed 270,000 year-long record of terrestrial climate variability in the KwaZulu-Natal province based on elemental ratios of Fe/K from the southwest Indian Ocean, derived from X-ray fluorescence core scanning. Eastern South African climate variability on these time scales reflects both the long-term effect of regional insolation changes driven by orbital precession and the effects associated with high-latitude abrupt climate forcing over the past two glacial-interglacial cycles, including millennial-scale events not previously identified. Rapid changes towards more humid conditions in eastern South Africa as the Northern Hemisphere entered phases of extreme cooling were potentially driven by a combination of warming in the Agulhas Current and shifts of the subtropical anticyclones. These climate oscillations appear coherent with other Southern Hemisphere records but are anti-phased with respect to the East Asian Monsoon. Numerical modelling results reveal that higher precipitation in the KwaZulu-Natal province during precession maxima is driven by a combination of increased local evaporation and elevated moisture transport into eastern South Africa from the coast of Mozambique.

Eastern South African hydroclimate over the past 270,000 years

PubMed Central

Simon, Margit H.; Ziegler, Martin; Bosmans, Joyce; Barker, Stephen; Reason, Chris J.C.; Hall, Ian R.

2015-01-01

Processes that control the hydrological balance in eastern South Africa on orbital to millennial timescales remain poorly understood because proxy records documenting its variability at high resolution are scarce. In this work, we present a detailed 270,000 year-long record of terrestrial climate variability in the KwaZulu-Natal province based on elemental ratios of Fe/K from the southwest Indian Ocean, derived from X-ray fluorescence core scanning. Eastern South African climate variability on these time scales reflects both the long-term effect of regional insolation changes driven by orbital precession and the effects associated with high-latitude abrupt climate forcing over the past two glacial-interglacial cycles, including millennial-scale events not previously identified. Rapid changes towards more humid conditions in eastern South Africa as the Northern Hemisphere entered phases of extreme cooling were potentially driven by a combination of warming in the Agulhas Current and shifts of the subtropical anticyclones. These climate oscillations appear coherent with other Southern Hemisphere records but are anti-phased with respect to the East Asian Monsoon. Numerical modelling results reveal that higher precipitation in the KwaZulu-Natal province during precession maxima is driven by a combination of increased local evaporation and elevated moisture transport into eastern South Africa from the coast of Mozambique. PMID:26686943

A physics-based fractional order model and state of energy estimation for lithium ion batteries. Part I: Model development and observability analysis

NASA Astrophysics Data System (ADS)

Li, Xiaoyu; Fan, Guodong; Pan, Ke; Wei, Guo; Zhu, Chunbo; Rizzoni, Giorgio; Canova, Marcello

2017-11-01

The design of a lumped parameter battery model preserving physical meaning is especially desired by the automotive researchers and engineers due to the strong demand for battery system control, estimation, diagnosis and prognostics. In light of this, a novel simplified fractional order electrochemical model is developed for electric vehicle (EV) applications in this paper. In the model, a general fractional order transfer function is designed for the solid phase lithium ion diffusion approximation. The dynamic characteristics of the electrolyte concentration overpotential are approximated by a first-order resistance-capacitor transfer function in the electrolyte phase. The Ohmic resistances and electrochemical reaction kinetics resistance are simplified to a lumped Ohmic resistance parameter. Overall, the number of model parameters is reduced from 30 to 9, yet the accuracy of the model is still guaranteed. In order to address the dynamics of phase-change phenomenon in the active particle during charging and discharging, variable solid-state diffusivity is taken into consideration in the model. Also, the observability of the model is analyzed on two types of lithium ion batteries subsequently. Results show the fractional order model with variable solid-state diffusivity agrees very well with experimental data at various current input conditions and is suitable for electric vehicle applications.

Synchronized metronome training induces changes in the kinematic properties of the golf swing.

PubMed

Sommer, Marius; Häger, Charlotte; Rönnqvist, Louise

2014-03-01

The purpose of this study was to evaluate possible effects of synchronized metronome training (SMT) on movement dynamics during golf-swing performance, as captured by kinematic analysis. A one-group, between-test design was applied on 13 male golfers (27.5 +/- 4.6 years old, 12.7 +/- 4.9 handicap) who completed 12 sessions of SMT over a four-week period. Pre- and post-assessments of golf swings with three different clubs (4-iron, 7-iron, and pitching wedge) were performed using a three-dimensional motion capture system. Club velocity at three different swing phases (backswing, downswing, and follow-through) was measured and cross-correlation analysis of time-series signals were made on joint couplings (wrist-elbow-shoulder) of both arms, and between joints and the club, during the full golf swing. There were significantly higher cross-correlations between joint-couplings and concomitant changes of the associated phase-shift differences, as well as reduced phase-shift variability at post-test. No significant effect of SMT was found for the club velocities. We suggest that domain-general influences of SMT on the underlying brain-based motor control strategies lead to a more coordinated movement pattern of the golf-swing performance, which may explain previous observations of significantly improved golf-shot accuracy and decreased variability after SMT.

Variable thickness double-refracting plate

DOEpatents

Hadeishi, Tetsuo

1976-01-01

This invention provides an A.C., cyclic, current-controlled, phase retardation plate that uses a magnetic clamp to produce stress birefringence. It was developed for an Isotope-Zeeman Atomic Absorption Spectrometer that uses polarization modulation to effect automatic background correction in atomic absorption trace-element measurements. To this end, the phase retardation plate of the invention is a variable thickness, photoelastic, double-refracting plate that is alternately stressed and released by the magnetic clamp selectively to modulate specific components selected from the group consisting of circularly and plane polarized Zeeman components that are produced in a dc magnetic field so that they correspond respectively to Zeeman reference and transmission-probe absorption components. The polarization modulation changes the phase of these polarized Zeeman components, designated as .sigma. reference and .pi. absorption components, so that every half cycle the components change from a transmission mode to a mode in which the .pi. component is blocked and the .sigma. components are transmitted. Thus, the Zeeman absorption component, which corresponds in amplitude to the amount of the trace element to be measured in a sample, is alternately transmitted and blocked by a linear polarizer, while the circularly polarized reference components are continuously transmitted thereby. The result is a sinusoidally varying output light amplitude whose average corresponds to the amount of the trace element present in the sample.

Paleotemperatures at the lunar surfaces from open system behavior of cosmogenic 38Ar and radiogenic 40Ar

DOE PAGES

Shuster, David L.; Cassata, William S.

2015-02-10

The simultaneous diffusion of both cosmogenic 38Ar and radiogenic 40Ar from solid phases is controlled by the thermal conditions of rocks while residing near planetary surfaces. Combined observations of 38Ar/ 37Ar and 40Ar/ 39Ar ratios during stepwise degassing analyses of neutron-irradiated Apollo samples can distinguish between diffusive loss of Ar due to solar heating of the rocks and that associated with elevated temperatures during or following impact events; the data provide quantitative constraints on the durations and temperatures of each process. From sequentially degassed 38Ar/ 37Ar ratios can be calculated a spectrum of apparent 38Ar exposure ages versus the cumulativemore » release fraction of 37Ar, which is particularly sensitive to conditions at the lunar surface typically over ~106–108 year timescales. Due to variable proportions of K- and Ca-bearing glass, plagioclase and pyroxene, with variability in the grain sizes of these phases, each sample will have distinct sensitivity to, and therefore different resolving power on, past near-surface thermal conditions. Furthermore, we present the underlying assumptions, and the analytical and numerical methods used to quantify the Ar diffusion kinetics in multi-phase whole-rock analyses that provide these constraints.« less

A speech-controlled environmental control system for people with severe dysarthria.

PubMed

Hawley, Mark S; Enderby, Pam; Green, Phil; Cunningham, Stuart; Brownsell, Simon; Carmichael, James; Parker, Mark; Hatzis, Athanassios; O'Neill, Peter; Palmer, Rebecca

2007-06-01

Automatic speech recognition (ASR) can provide a rapid means of controlling electronic assistive technology. Off-the-shelf ASR systems function poorly for users with severe dysarthria because of the increased variability of their articulations. We have developed a limited vocabulary speaker dependent speech recognition application which has greater tolerance to variability of speech, coupled with a computerised training package which assists dysarthric speakers to improve the consistency of their vocalisations and provides more data for recogniser training. These applications, and their implementation as the interface for a speech-controlled environmental control system (ECS), are described. The results of field trials to evaluate the training program and the speech-controlled ECS are presented. The user-training phase increased the recognition rate from 88.5% to 95.4% (p<0.001). Recognition rates were good for people with even the most severe dysarthria in everyday usage in the home (mean word recognition rate 86.9%). Speech-controlled ECS were less accurate (mean task completion accuracy 78.6% versus 94.8%) but were faster to use than switch-scanning systems, even taking into account the need to repeat unsuccessful operations (mean task completion time 7.7s versus 16.9s, p<0.001). It is concluded that a speech-controlled ECS is a viable alternative to switch-scanning systems for some people with severe dysarthria and would lead, in many cases, to more efficient control of the home.

Switching in Feedforward Control of Grip Force During Tool-Mediated Interaction With Elastic Force Fields

PubMed Central

White, Olivier; Karniel, Amir; Papaxanthis, Charalambos; Barbiero, Marie; Nisky, Ilana

2018-01-01

Switched systems are common in artificial control systems. Here, we suggest that the brain adopts a switched feedforward control of grip forces during manipulation of objects. We measured how participants modulated grip force when interacting with soft and rigid virtual objects when stiffness varied continuously between trials. We identified a sudden phase transition between two forms of feedforward control that differed in the timing of the synchronization between the anticipated load force and the applied grip force. The switch occurred several trials after a threshold stiffness level in the range 100–200 N/m. These results suggest that in the control of grip force, the brain acts as a switching control system. This opens new research questions as to the nature of the discrete state variables that drive the switching. PMID:29930504

Quasi-experimental study designs series-paper 9: collecting data from quasi-experimental studies.

PubMed

Aloe, Ariel M; Becker, Betsy Jane; Duvendack, Maren; Valentine, Jeffrey C; Shemilt, Ian; Waddington, Hugh

2017-09-01

To identify variables that must be coded when synthesizing primary studies that use quasi-experimental designs. All quasi-experimental (QE) designs. When designing a systematic review of QE studies, potential sources of heterogeneity-both theory-based and methodological-must be identified. We outline key components of inclusion criteria for syntheses of quasi-experimental studies. We provide recommendations for coding content-relevant and methodological variables and outlined the distinction between bivariate effect sizes and partial (i.e., adjusted) effect sizes. Designs used and controls used are viewed as of greatest importance. Potential sources of bias and confounding are also addressed. Careful consideration must be given to inclusion criteria and the coding of theoretical and methodological variables during the design phase of a synthesis of quasi-experimental studies. The success of the meta-regression analysis relies on the data available to the meta-analyst. Omission of critical moderator variables (i.e., effect modifiers) will undermine the conclusions of a meta-analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

Interannual variability of cut-off low systems over the European sector: The role of blocking and the Northern Hemisphere circulation modes

NASA Astrophysics Data System (ADS)

Nieto, R.; Gimeno, L.; de La Torre, L.; Ribera, P.; Barriopedro, D.; García-Herrera, R.; Serrano, A.; Gordillo, A.; Redaño, A.; Lorente, J.

2007-04-01

An earlier developed multidecadal database of Northern Hemisphere cut-off low systems (COLs), covering a 41 years period (from 1958 to 1998) is used to study COLs interannual variability in the European sector (25°-47.5° N, 50° W-40° E) and the major factors controlling it. The study focus on the influence on COLs interannual variability, of larger scale phenomena such as blocking events and other main circulation modes defined over the Euro-Atlantic region. It is shown that there is a very large interannual variability in the COLs occurrence at the annual and seasonal scales, although without significant trends. The influence of larger scale phenomena is seasonal dependent, with the positive phase of the NAO favoring autumn COL development, while winter COL occurrence is mostly related to blocking events. During summer, the season when more COLs occur, no significant influences were found.

Drag, but not buoyancy, affects swim speed in captive Steller sea lions

PubMed Central

Suzuki, Ippei; Sato, Katsufumi; Fahlman, Andreas; Naito, Yasuhiko; Miyazaki, Nobuyuki; Trites, Andrew W.

2014-01-01

ABSTRACT Swimming at an optimal speed is critical for breath-hold divers seeking to maximize the time they can spend foraging underwater. Theoretical studies have predicted that the optimal swim speed for an animal while transiting to and from depth is independent of buoyancy, but is dependent on drag and metabolic rate. However, this prediction has never been experimentally tested. Our study assessed the effects of buoyancy and drag on the swim speed of three captive Steller sea lions (Eumetopias jubatus) that made 186 dives. Our study animals were trained to dive to feed at fixed depths (10–50 m) under artificially controlled buoyancy and drag conditions. Buoyancy and drag were manipulated using a pair of polyvinyl chloride (PVC) tubes attached to harnesses worn by the sea lions, and buoyancy conditions were designed to fall within the natural range of wild animals (∼12–26% subcutaneous fat). Drag conditions were changed with and without the PVC tubes, and swim speeds were recorded and compared during descent and ascent phases using an accelerometer attached to the harnesses. Generalized linear mixed-effect models with the animal as the random variable and five explanatory variables (body mass, buoyancy, dive depth, dive phase, and drag) showed that swim speed was best predicted by two variables, drag and dive phase (AIC = −139). Consistent with a previous theoretical prediction, the results of our study suggest that the optimal swim speed of Steller sea lions is a function of drag, and is independent of dive depth and buoyancy. PMID:24771620

Understanding the contribution of phytoplankton phase functions to uncertainties in the water colour signal.

PubMed

Lain, Lisl Robertson; Bernard, Stewart; Matthews, Mark W

2017-02-20

The accurate description of a water body's volume scattering function (VSF), and hence its phase functions, is critical to the determination of the constituent inherent optical properties (IOPs), the associated spectral water-leaving reflectance, and consequently the retrieval of phytoplankton functional type (PFT) information. The equivalent algal populations (EAP) model has previously been evaluated for phytoplankton-dominated waters, and offers the ability to provide phytoplankton population-specific phase functions, unveiling a new opportunity to further understanding of the causality of the PFT signal. This study presents and evaluates the wavelength dependent, spectrally variable EAP particle phase functions and the subsequent effects on water-leaving reflectance. Comparisons are made with frequently used phase function approximations e.g. the Fournier Forand formulation, as well as with phase functions inferred from measured VSFs in coastal waters. Relative differences in shape and magnitude are quantified. Reflectance modelled with the EAP phase functions is then compared against measured reflectance data from phytoplankton-dominated waters. Further examples of modelled phytoplankton-dominated waters are discussed with reference to choice of phase function for two PFTs (eukaryote and prokaryote) across a range of biomass. Finally a demonstration of the sensitivity of reflectance due to the choice of phase function is presented. The EAP model phase functions account for both spectral and angular variability in phytoplankton backscattering i.e. they display variability which is both spectral and shape-related. It is concluded that phase functions modelled in this way are necessary for investigating the effects of assemblage variability on the ocean colour signal, and should be considered for model closure even in relatively low scattering conditions where phytoplankton dominate the IOPs.

Predictors of Hypoglycemia in the ASPIRE In-Home Study and Effects of Automatic Suspension of Insulin Delivery.

PubMed

Weiss, Ram; Garg, Satish K; Bergenstal, Richard M; Klonoff, David C; Bode, Bruce W; Bailey, Timothy S; Thrasher, James; Schwartz, Frank; Welsh, John B; Kaufman, Francine R

2015-05-18

Hypoglycemia varies between patients with type 1 diabetes and is the main obstacle to therapy intensification. We investigated known and potential risk factors for hypoglycemia in subjects with type 1 diabetes. In the ASPIRE In-Home study (NCT01497938), a randomized trial of the threshold suspend (TS) feature of sensor-augmented insulin pump (SAP) therapy, subjects' propensity to nocturnal hypoglycemia (NH) was established in a 2-week run-in phase and assessed in a 3-month study phase via continuous glucose monitoring. Categorical variables were tested for association with NH rates in both phases. Elevated rates of NH were significantly associated with baseline A1C ≤7%, with bolus insulin deliveries unassisted by the bolus estimation calculator, and with assignment to the control group during the study phase. Routine use of the TS feature and the bolus estimation calculator are strategies that may reduce the risk of NH. © 2015 Diabetes Technology Society.

Simple and Double Alfven Waves: Hamiltonian Aspects

NASA Astrophysics Data System (ADS)

Webb, G. M.; Zank, G. P.; Hu, Q.; le Roux, J. A.; Dasgupta, B.

2011-12-01

We discuss the nature of simple and double Alfvén waves. Simple waves depend on a single phase variable \\varphi, but double waves depend on two independent phase variables \\varphi1 and \\varphi2. The phase variables depend on the space and time coordinates x and t. Simple and double Alfvén waves have the same integrals, namely, the entropy, density, magnetic pressure, and group velocity (the sum of the Alfvén and fluid velocities) are constant throughout the flow. We present examples of both simple and double Alfvén waves, and discuss Hamiltonian formulations of the waves.

Predictive Variables of Half-Marathon Performance for Male Runners.

PubMed

Gómez-Molina, Josué; Ogueta-Alday, Ana; Camara, Jesus; Stickley, Christoper; Rodríguez-Marroyo, José A; García-López, Juan

2017-06-01

The aims of this study were to establish and validate various predictive equations of half-marathon performance. Seventy-eight half-marathon male runners participated in two different phases. Phase 1 (n = 48) was used to establish the equations for estimating half-marathon performance, and Phase 2 (n = 30) to validate these equations. Apart from half-marathon performance, training-related and anthropometric variables were recorded, and an incremental test on a treadmill was performed, in which physiological (VO 2max , speed at the anaerobic threshold, peak speed) and biomechanical variables (contact and flight times, step length and step rate) were registered. In Phase 1, half-marathon performance could be predicted to 90.3% by variables related to training and anthropometry (Equation 1), 94.9% by physiological variables (Equation 2), 93.7% by biomechanical parameters (Equation 3) and 96.2% by a general equation (Equation 4). Using these equations, in Phase 2 the predicted time was significantly correlated with performance (r = 0.78, 0.92, 0.90 and 0.95, respectively). The proposed equations and their validation showed a high prediction of half-marathon performance in long distance male runners, considered from different approaches. Furthermore, they improved the prediction performance of previous studies, which makes them a highly practical application in the field of training and performance.

Low velocity opposed-flow frame spread in a transport-controlled environment DARTFire

NASA Technical Reports Server (NTRS)

West, Jeff; Thomas, Pete; Chao, Ruian; Bhattacharjee, Subrata; Tang, TI; Altenkirch, Robert A.; Olson, Sandra L.

1995-01-01

The overall objectives of the DARTFire project are to uncover the underlying physics and increase understanding of the mechanisms that cause flames to propagate over solid fuels against a low velocity of oxidizer flow in a low-gravity environment. Specific objectives are (1) to analyze experimentally observed flame shapes, measured gas-phase field variables, spread rates, radiative characteristics, and solid-phase regression rates for comparison with previously developed model prediction capability that will be continually extended, and (2) to investigate the transition from ignition to either flame propagation or extinction in order to determine the characteristics of those environments that lead to flame evolution. To meet the objectives, a series of sounding rocket experiments has been designed to exercise several of the dimensional, controllable variables that affect the flame spread process over PMMA in microgravity, i.e., the opposing flow velocity (1-20 cm/s), the external radiant flux directed to the fuel surface (0-2 W/cm(exp 2)), and the oxygen concentration of the environment (35-70%). Because radiative heat transfer is critical to these microgravity flame spread experiments, radiant heating is imposed, and radiant heat loss will be measured. These are the first attempts at such an experimental control and measurement in microgravity. Other firsts associated with the experiment are (1) the control of the low velocity, opposed flow, which is of the same order as diffusive velocities and Stefan flows; (2) state-of-the-art quantitative flame imaging for species-specific emissions (both infrared and ultraviolet) in addition to novel intensified array imaging to obtain a color image of the very dim, low-gravity flames.

Effects of Respiratory Training on Heart Rate Variability and Baroreflex Sensitivity in Individuals With Chronic Spinal Cord Injury.

PubMed

Legg Ditterline, Bonnie E; Aslan, Sevda C; Randall, David C; Harkema, Susan J; Castillo, Camilo; Ovechkin, Alexander V

2018-03-01

To evaluate the effects of pressure threshold respiratory training (RT) on heart rate variability and baroreflex sensitivity in persons with chronic spinal cord injury (SCI). Before-after intervention case-controlled clinical study. SCI research center and outpatient rehabilitation unit. Participants (N=44) consisted of persons with chronic SCI ranging from C2 to T11 who participated in RT (n=24), and untrained control subjects with chronic SCI ranging from C2 to T9 (n=20). A total of 21±2 RT sessions performed 5 days a week during a 4-week period using a combination of pressure threshold inspiratory and expiratory devices. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV 1 ), and beat-to-beat arterial blood pressure and heart rate changes during the 5-second-long maximum expiratory pressure maneuver (5s MEP) and the sit-up orthostatic stress test, acquired before and after the RT program. In contrast to the untrained controls, individuals in the RT group experienced significantly increased FVC and FEV 1 (both P<.01) in association with improved quality of sleep, cough, and speech. Sympathetically (phase II) and parasympathetically (phase IV) mediated baroreflex sensitivity both significantly (P<.05) increased during the 5s MEP. During the orthostatic stress test, improved autonomic control over heart rate was associated with significantly increased sympathetic and parasympathetic modulation (low- and high-frequency change: P<.01 and P<.05, respectively). Inspiratory-expiratory pressure threshold RT is a promising technique to positively affect both respiratory and cardiovascular dysregulation observed in persons with chronic SCI. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Modeling mechanical properties of a shear thickening fluid damper based on phase transition theory

NASA Astrophysics Data System (ADS)

Wei, Minghai; Lin, Kun; Guo, Qian

2018-03-01

Shear thickening fluids (STFs) are highly concentrated colloidal suspensions consisting of monodisperse nano-particles suspended in a carrying fluid, and have the capacity to display both flowable and rigid behaviors, when subjected to sudden stimuli. In that process, the external energy that acts on an STF can be dissipated quickly. The aim of this study is to present a dynamic model of a damper filled with STF that can be directly used in control engineering fields. To this end, shear stress during phase transition of the STF material is chosen as an internal variable. A non-convex function with bifurcation behavior is used to describe the phase transitioning of STF by determining the relationship between the behavioral characteristics of the microscopic phase and macroscopic damping force. This model is able to predict force-velocity and force-displacement relationships as functions of the loading frequency. Efficacy of the model is demonstrated via comparison with experimental results from previous studies. In addition, the results confirm the hypothesis regarding the occurrence of STF phase transitioning when subject to shear stress.

The preanalytic phase in veterinary clinical pathology.

PubMed

Braun, Jean-Pierre; Bourgès-Abella, Nathalie; Geffré, Anne; Concordet, Didier; Trumel, Cathy

2015-03-01

This article presents the general causes of preanalytic variability with a few examples showing specialists and practitioners that special and improved care should be given to this too often neglected phase. The preanalytic phase of clinical pathology includes all the steps from specimen collection to analysis. It is the phase where most laboratory errors occur in human, and probably also in veterinary clinical pathology. Numerous causes may affect the validity of the results, including technical factors, such as the choice of anticoagulant, the blood vessel sampled, and the duration and conditions of specimen handling. While the latter factors can be defined, influence of biologic and physiologic factors such as feeding and fasting, stress, and biologic and endocrine rhythms can often not be controlled. Nevertheless, as many factors as possible should at least be documented. The importance of the preanalytic phase is often not given the necessary attention, although the validity of the results and consequent clinical decision making and medical management of animal patients would likely be improved if the quality of specimens submitted to the laboratory was optimized. © 2014 American Society for Veterinary Clinical Pathology.

Grassmann phase space theory and the Jaynes–Cummings model

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

Dalton, B.J., E-mail: bdalton@swin.edu.au; Centre for Atom Optics and Ultrafast Spectroscopy, Swinburne University of Technology, Melbourne, Victoria 3122; Garraway, B.M.

2013-07-15

The Jaynes–Cummings model of a two-level atom in a single mode cavity is of fundamental importance both in quantum optics and in quantum physics generally, involving the interaction of two simple quantum systems—one fermionic system (the TLA), the other bosonic (the cavity mode). Depending on the initial conditions a variety of interesting effects occur, ranging from ongoing oscillations of the atomic population difference at the Rabi frequency when the atom is excited and the cavity is in an n-photon Fock state, to collapses and revivals of these oscillations starting with the atom unexcited and the cavity mode in a coherentmore » state. The observation of revivals for Rydberg atoms in a high-Q microwave cavity is key experimental evidence for quantisation of the EM field. Theoretical treatments of the Jaynes–Cummings model based on expanding the state vector in terms of products of atomic and n-photon states and deriving coupled equations for the amplitudes are a well-known and simple method for determining the effects. In quantum optics however, the behaviour of the bosonic quantum EM field is often treated using phase space methods, where the bosonic mode annihilation and creation operators are represented by c-number phase space variables, with the density operator represented by a distribution function of these variables. Fokker–Planck equations for the distribution function are obtained, and either used directly to determine quantities of experimental interest or used to develop c-number Langevin equations for stochastic versions of the phase space variables from which experimental quantities are obtained as stochastic averages. Phase space methods have also been developed to include atomic systems, with the atomic spin operators being represented by c-number phase space variables, and distribution functions involving these variables and those for any bosonic modes being shown to satisfy Fokker–Planck equations from which c-number Langevin equations are often developed. However, atomic spin operators satisfy the standard angular momentum commutation rules rather than the commutation rules for bosonic annihilation and creation operators, and are in fact second order combinations of fermionic annihilation and creation operators. Though phase space methods in which the fermionic operators are represented directly by c-number phase space variables have not been successful, the anti-commutation rules for these operators suggest the possibility of using Grassmann variables—which have similar anti-commutation properties. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of phase space methods in quantum optics to treat fermionic systems by representing fermionic annihilation and creation operators directly by Grassmann phase space variables is rather rare. This paper shows that phase space methods using a positive P type distribution function involving both c-number variables (for the cavity mode) and Grassmann variables (for the TLA) can be used to treat the Jaynes–Cummings model. Although it is a Grassmann function, the distribution function is equivalent to six c-number functions of the two bosonic variables. Experimental quantities are given as bosonic phase space integrals involving the six functions. A Fokker–Planck equation involving both left and right Grassmann differentiations can be obtained for the distribution function, and is equivalent to six coupled equations for the six c-number functions. The approach used involves choosing the canonical form of the (non-unique) positive P distribution function, in which the correspondence rules for the bosonic operators are non-standard and hence the Fokker–Planck equation is also unusual. Initial conditions, such as those above for initially uncorrelated states, are discussed and used to determine the initial distribution function. Transformations to new bosonic variables rotating at the cavity frequency enable the six coupled equations for the new c-number functions–that are also equivalent to the canonical Grassmann distribution function–to be solved analytically, based on an ansatz from an earlier paper by Stenholm. It is then shown that the distribution function is exactly the same as that determined from the well-known solution based on coupled amplitude equations. In quantum–atom optics theories for many atom bosonic and fermionic systems are needed. With large atom numbers, treatments must often take into account many quantum modes—especially for fermions. Generalisations of phase space distribution functions of phase space variables for a few modes to phase space distribution functionals of field functions (which represent the field operators, c-number fields for bosons, Grassmann fields for fermions) are now being developed for large systems. For the fermionic case, the treatment of the simple two mode problem represented by the Jaynes–Cummings model is a useful test case for the future development of phase space Grassmann distribution functional methods for fermionic applications in quantum–atom optics. -- Highlights: •Novel phase space theory of the Jaynes–Cummings model using Grassmann variables. •Fokker–Planck equations solved analytically. •Results agree with the standard quantum optics treatment. •Grassmann phase space theory applicable to fermion many-body problems.« less

The increasing control of the Atlantic Ocean on ENSO after the early 1990s

NASA Astrophysics Data System (ADS)

Yu, J. Y.; Paek, H.; Wang, L.; Lyu, K.

2016-12-01

The El Niño-Southern Oscillation (ENSO) is the most powerful interannual variability in Earth's climate system. Previous studies have emphasized processes within the tropical Pacific or Indian Oceans for the generation of ENSO. Recent studies have increasingly suggested that the Atlantic Ocean may play an active role in forcing ENSO variability. In this talk, we will present evidence from observational analyses and modeling experiments to show that the Atlantic Ocean became more capable of influencing ENSO properties after the Atlantic Multidecadal Oscillation (AMO) changed to its positive phase in the early-1990s. A wave source mechanism is proposed to explain how the positive phase of the AMO can intensify the North Pacific Subtropical High (NPSH) to change the ENSO from the Eastern Pacific (EP) type to the Central Pacific (CP) type. A sequence of processes are identified to suggest that the AMO can displace the Pacific Walker circulation, induce a wave source in the tropical central Pacific, and excite a barotropic wave train toward higher-latitudes to enhance the NPSH, which then triggers subtropical Pacific atmospheric forcing and atmosphere-ocean coupling to increase the occurrence of the CP ENSO. An Atlantic capacitor mechanism is also proposed to explain how the positive phase of the AMO can intensify the quasi-biennial (QB) component of ENSO resulting in a more frequent occurrence of ENSO events. We will show that the capacitor mechanism works only after the AMO warmed up the Atlantic sea surface temperatures after the early-1990s. The increased feedback from the Atlantic to the Pacific has enabled the Atlantic capacitor mechanism to intensify the biennial variability in the Pacific during the past two decades. Our suggestion is very different from the previous prevailing views that have emphasized the Indo-Pacific Oceans as the pacemaker for the biennial variability in ENSO. The increasing control of the Atlantic has enabled the CP ENSO dynamics to influence most of the ENSO events during the past two decades, including the most recent 2015-16 El Niño. We will explain how the CP ENSO dynamics made the 2015-16 "Godzilla" El Niño different from the 1997-98 "Godzilla" El Niño and why these two extreme El Niño events produced different impacts on the US climate.

Cyclic Activity of Mud Volcanoes: Evidences from Trinidad (SE Caribbean)

NASA Astrophysics Data System (ADS)

Deville, E.

2007-12-01

Fluid and solid transfer in mud volcanoes show different phases of activity, including catastrophic events followed by periods of relative quiescence characterized by moderate activity. This can be notably shown by historical data onshore Trinidad. Several authors have evoked a possible link between the frequencies of eruption of some mud volcanoes and seismic activity, but in Trinidad there is no direct correlation between mud eruptions and seisms. It appears that each eruptive mud volcano has its own period of catastrophic activity, and this period is highly variable from one volcano to another. The frequency of activity of mud volcanoes seems essentially controlled by local pressure regime within the sedimentary pile. At the most, a seism can, in some cases, activate an eruption close to its term. The dynamics of expulsion of the mud volcanoes during the quiescence phases has been studied notably from temperature measurements within the mud conduits. The mud temperature is concurrently controlled by, either, the gas flux (endothermic gas depressurizing induces a cooling effect), or by the mud flux (mud is a vector for convective heat transfer). Complex temperature distribution was observed in large conduits and pools. Indeed, especially in the bigger pools, the temperature distribution characterizes convective cells with an upward displacement of mud above the deep outlet, and ring-shaped rolls associated with the burial of the mud on the flanks of the pools. In simple, tube-like shaped, narrow conduits, the temperature is more regular, but we observed different types of profiles, with either downward increasing or decreasing temperatures. If the upward flow of mud would be regular, we should expect increasing temperatures and progressively decreasing gradient with depth within the conduits. However, the variable measured profiles from one place to another, as well as time-variable measured temperatures within the conduits and especially, at the base of the conduits, shows that the fluid flow expelled by the studied mud volcanoes is not constant but highly variable through short time-periods. We notably observed very short time-period cyclic variations with a frequency of about 10 minutes. These high frequencies temperature changes could be related to the dynamics of two-phase flows (gas and mud) through the mud volcano conduits. We also observed locally a significant daily changes of the temperature of the expelled mud which shows also that the mud flux is changing very rapidly from one day to another.

Spatial variability and its main controlling factors of the permafrost soil-moisture on the northern-slope of Bayan Har Mountains in Qinghai-Tibet Plateau

NASA Astrophysics Data System (ADS)

Cao, W.; Sheng, Y.

2017-12-01

The soil moisture movement is an important carrier of material cycle and energy flow among the various geo-spheres in the cold regions. It is very critical to protect the alpine ecology and hydrologic cycle in Qinghai-Tibet Plateau. Especially, it becomes one of the key problems to reveal the spatial-temporal variability of soil moisture movement and its main influence factors in earth system science. Thus, this research takes the north slope of Bayan Har Mountains in Qinghai-Tibet Plateau as a case study. The present study firstly investigates the change of permafrost moisture in different slope positions and depths. Based on this investigation, this article attempts to investigate the spatial variability of permafrost moisture and identifies the key influence factors in different terrain conditions. The method of classification and regression tree (CART) is adopted to identify the main controlling factors influencing the soil moisture movement. And the relationships between soil moisture and environmental factors are revealed by the use of the method of canonical correspondence analysis (CCA). The results show that: 1) the change of the soil moisture on the permafrost slope is divided into 4 stages, including the freezing stability phase, the rapid thawing phase, the thawing stability phase and the fast freezing phase; 2) this greatly enhances the horizontal flow in the freezing period due to the terrain slope and the freezing-thawing process. Vertical migration is the mainly form of the soil moisture movement. It leads to that the soil-moisture content in the up-slope is higher than that in the down-slope. On the contrary, the soil-moisture content in the up-slope is lower than that in the down-slope during the melting period; 3) the main environmental factors which affect the slope-permafrost soil-moisture are elevation, soil texture, soil temperature and vegetation coverage. But there are differences in the impact factors of the soil moisture in different freezing-thawing stages; 4) the main factors that affect the slope-permafrost soil-moisture at the shallow depth of 0-20cm are slope, elevation and vegetation coverage. And the main factors influencing the soil moisture at the middle and lower depth are complex.

Anxiety and depression in care homes in Malta and Australia: Part 1.

PubMed

Baldacchino, Donia R; Bonello, Lilian

This cross-sectional comparative study, conducted in two phases, assessed the levels of and factors contributing towards anxiety and depression in older people in residential homes in Malta and Australia. A mixed-method approach was adopted and the cognitive theory of stress and coping (Lazarus and Folkman, 1984) guided the study. Maltese residents were recruited from four church-run homes in Malta and Australia and two state residences in Malta. Response rates were high, with phase 1 at 94.48% (n = 137; mean age = 72.8 years) and phase 2 at 89.4%, (n = 42, mean age = 71.9 years). All the residents were mobile, were Roman Catholics and had lived in the homes for at least 6 months. In phase 1, quantitative data was collected using a demographic questionnaire and the hospital anxiety and depression scale. Normal ranges of anxiety and depression were found (anxiety: mean = 3.53-4.35; depression: mean = 2.67-4.72). No significant differences were found in anxiety and depression between countries, demographic characteristics and some other variables. The only significant difference lay in depression by mobility (F = 5.263; P = 0.006; df = 2), with wheelchair users scoring the highest mean (mean = 6.77; SD = 5.847; P = 0.007). Mobility was linked to functional abilities, which appeared to control anxiety and depression. Recommendations are made for rehabilitation and cross-cultural longitudinal research to investigate other influencing variables such as spirituality and caring relationships.

Single-breath CO2 analysis as a predictor of lung volume in a healthy animal model during controlled ventilation.

PubMed

Stenz, R I; Grenier, B; Thompson, J E; Arnold, J H

1998-08-01

To examine the utility of single-breath CO2 analysis as a measure of lung volume. A prospective, animal cohort study comparing 21 parameters derived from single-breath CO2 analysis with lung volume measurements determined by nitrogen washout in animals during controlled ventilation. An animal laboratory in a university-affiliated medical center. Seven healthy lambs. The single-breath CO2 analysis station consists of a mainstream capnometer, a variable orifice pneumotachometer, a signal processor and computer software with capability for both on- and off-line data analysis. Twenty-one derived components of the CO2 expirogram were evaluated as predictors of lung volume. Lung volume was manipulated by 3 cm H2O incremental increases in positive end-expiratory pressure from 0 to 21 cm H2O, and ranged between 147 and 942 mL. Fifty-five measurements of lung volume were available for comparison with derived variables from the CO2 expirogam. Stepwise linear regression identified four variables that were most predictive of lung volume: a) dynamic lung compliance; b) the slope of phase 3; c) the slope of phase 2 divided by the mixed expired CO2 tension; and d) airway deadspace. The multivariate equation was highly statistically significant and explained 94% of the variance (adjusted r2 =.94, p < .0001). The bias and precision of the calculated lung volume was .00 and 51, respectively. The mean percent difference for the lung volume estimate derived from the single-breath CO2 analysis station was 0.79%. Our data indicate that analysis of the CO2 expirogram can yield accurate information about lung volume. Specifically, four variables derived from a plot of expired CO2 concentration vs. expired volume predict changes in lung volume in healthy lambs with an adjusted coefficient of determination of .94. Prospective application of this technology in the setting of lung injury and rapidly changing physiology is essential in determining the clinical usefulness of the technique.

Correlations between the circadian patterns of body temperature, metabolism and breathing in rats.

PubMed

Mortola, Jacopo P

2007-02-15

It had been demonstrated previously that the circadian patterns of activity and state of arousal are not essential for the manifestation of the daily patterns of pulmonary ventilation (V(E)), tidal volume (V(T)) and breathing frequency (f). In this study we investigated the extent of the linkage between the circadian pattern of breathing and those of body temperature (T(b)) and metabolic rate (oxygen consumption, V(O2), and carbon dioxide production, V(CO2)). Rats were instrumented for measurements of T(b) (by telemetry), and placed in a chamber for continuous 13-day period of measurement of breathing (by a modification of the barometric methodology), and of V(O2) and V(CO2) (by an open flow method). After the first 4 days in control conditions under a 12 h light:12 h dark (L:D) cycle, a perturbation was introduced on day 4, with an L-phase prolongation of 12 h, and on day 9, with an D-phase prolongation of 12 h. During the control days 1-4, all variables had daily oscillations (higher values in D), in phase with each other. During the perturbations (days 4-13), changes in T(b), V(O2) and V(CO2), averaged over the whole period, correlated significantly better with f than with V(T). Day-by-day X-Y loops indicated that V (E), V(T) and f could lead significantly the changes of T(b), V(O2) and V(CO2), and that these relations changed throughout the perturbation period. In addition, f and V(T) did not change necessarily in phase with each other. It is concluded that neither the oscillation in T(b) nor that in metabolism can be considered the direct cause of the daily oscillation of breathing. Presumably, the circadian pattern of breathing reflects the interplay of the daily patterns of many variables, none acting as the primary guide of the breathing daily rhythm.

X-29 Research Pilot Rogers Smith

NASA Technical Reports Server (NTRS)

1988-01-01

Rogers Smith, a NASA research pilot, is seen here at the cockpit of the X-29 forward-swept-wing technology demonstrator at NASA's Ames-Dryden Flight Research Facility (later the Dryden Flight Research Center), Edwards, California, in 1988. The X-29 explored the use of advanced composites in aircraft construction; variable camber wing surfaces; the unique forward-swept-wing and its thin supercritical airfoil; strake flaps; and a computerized fly-by-wire flight control system that overcame the aircraft's instability. Grumman Aircraft Corporation built two X-29s. They were flight tested at Dryden from 1984 to 1992 in a joint NASA, DARPA (Defense Advanced Research Projects Agency) and U.S. Air Force program. Two X-29 aircraft, featuring one of the most unusual designs in aviation history, flew at the Ames-Dryden Flight Research Facility (now the Dryden Flight Research Center, Edwards, California) from 1984 to 1992. The fighter-sized X-29 technology demonstrators explored several concepts and technologies including: the use of advanced composites in aircraft construction; variable-camber wing surfaces; a unique forward- swept wing and its thin supercritical airfoil; strakes; close-coupled canards; and a computerized fly-by-wire flight control system used to maintain control of the otherwise unstable aircraft. Research results showed that the configuration of forward-swept wings, coupled with movable canards, gave pilots excellent control response at angles of attack of up to 45 degrees. During its flight history, the X-29 aircraft flew 422 research missions and a total of 436 missions. Sixty of the research flights were part of the X-29 follow-on 'vortex control' phase. The forward-swept wing of the X-29 resulted in reverse airflow, toward the fuselage rather than away from it, as occurs on the usual aft-swept wing. Consequently, on the forward-swept wing, the ailerons remained unstalled at high angles of attack. This provided better airflow over the ailerons and prevented stalling (loss of lift) at high angles of attack. Introduction of composite materials in the 1970s opened a new field of aircraft construction. It also made possible the construction of the X-29's thin supercritical wing. State-of-the-art composites allowed aeroelastic tailoring which, in turn, allowed the wing some bending but limited twisting and eliminated structural divergence within the flight envelope (i.e. deformation of the wing or the wing breaking off in flight). Additionally, composite materials allowed the wing to be sufficiently rigid for safe flight without adding an unacceptable weight penalty. The X-29 project consisted of two phases plus the follow-on vortex-control phase. Phase 1 demonstrated that the forward sweep of the X-29 wings kept the wing tips unstalled at the moderate angles of attack flown in that phase (a maximum of 21 degrees). Phase I also demonstrated that the aeroelastic tailored wing prevented structural divergence of the wing within the flight envelope, and that the control laws and control-surface effectiveness were adequate to provide artificial stability for an otherwise unstable aircraft. Phase 1 further demonstrated that the X-29 configuration could fly safely and reliably, even in tight turns. During Phase 2 of the project, the X-29, flying at an angle of attack of up to 67 degrees, demonstrated much better control and maneuvering qualities than computational methods and simulation models had predicted . During 120 research flights in this phase, NASA, Air Force, and Grumman project pilots reported the X-29 aircraft had excellent control response to an angle of attack of 45 degrees and still had limited controllability at a 67-degree angle of attack. This controllability at high angles of attack can be attributed to the aircraft's unique forward-swept wing- canard design. The NASA/Air Force-designed high-gain flight control laws also contributed to the good flying qualities. During the Air Force-initiated vortex-control phase, the X-29 successfully demonstrated vortex flow control (VFC). This VFC was more effective than expected in generating yaw forces, especially in high angles of attack where the rudder is less effective. VFC was less effective in providing control when sideslip (wind pushing on the side of the aircraft) was present, and it did little to decrease rocking oscillation of the aircraft. The X-29 vehicle was a single-engine aircraft, 48.1 feet long with a wing span of 27.2 feet. Each aircraft was powered by a General Electric F404-GE-400 engine producing 16,000 pounds of thrust. The program was a joint effort of the Department of Defense's Defense Advanced Research Projects Agency (DARPA), the U.S. Air Force, the Ames-Dryden Flight Research Facility, the Air Force Flight Test Center, and the Grumman Corporation. The program was managed by the Air Force's Wright Laboratory, Wright Patterson Air Force Base, Ohio.

Arctic Climate and Atmospheric Planetary Waves

NASA Technical Reports Server (NTRS)

Cavalieri, D. J.; Haekkinen, S.

2000-01-01

Analysis of a fifty-year record (1946-1995) of monthly-averaged sea level pressure data provides a link between the phases of planetary-scale sea level pressure waves and Arctic Ocean and ice variability. Results of this analysis show: (1) a breakdown of the dominant wave I pattern in the late 1960's, (2) shifts in the mean phase of waves 1 and 2 since this breakdown, (3) an eastward shift in the phases of both waves 1 and 2 during the years of simulated cyclonic Arctic Ocean circulation relative to their phases during the years of anticyclonic circulation, (4) a strong decadal variability of wave phase associated with simulated Arctic Ocean circulation changes. Finally, the Arctic atmospheric circulation patterns that emerge when waves 1 and 2 are in their extreme eastern and western positions suggest an alternative approach to determine significant forcing patterns of sea ice and high-latitude variability.

Mutually unbiased coarse-grained measurements of two or more phase-space variables

NASA Astrophysics Data System (ADS)

Paul, E. C.; Walborn, S. P.; Tasca, D. S.; Rudnicki, Łukasz

2018-05-01

Mutual unbiasedness of the eigenstates of phase-space operators—such as position and momentum, or their standard coarse-grained versions—exists only in the limiting case of infinite squeezing. In Phys. Rev. Lett. 120, 040403 (2018), 10.1103/PhysRevLett.120.040403, it was shown that mutual unbiasedness can be recovered for periodic coarse graining of these two operators. Here we investigate mutual unbiasedness of coarse-grained measurements for more than two phase-space variables. We show that mutual unbiasedness can be recovered between periodic coarse graining of any two nonparallel phase-space operators. We illustrate these results through optics experiments, using the fractional Fourier transform to prepare and measure mutually unbiased phase-space variables. The differences between two and three mutually unbiased measurements is discussed. Our results contribute to bridging the gap between continuous and discrete quantum mechanics, and they could be useful in quantum-information protocols.

A Lean Six Sigma approach to the improvement of the selenium analysis method.

PubMed

Cloete, Bronwyn C; Bester, André

2012-11-02

Reliable results represent the pinnacle assessment of quality of an analytical laboratory, and therefore variability is considered to be a critical quality problem associated with the selenium analysis method executed at Western Cape Provincial Veterinary Laboratory (WCPVL). The elimination and control of variability is undoubtedly of significant importance because of the narrow margin of safety between toxic and deficient doses of the trace element for good animal health. A quality methodology known as Lean Six Sigma was believed to present the most feasible solution for overcoming the adverse effect of variation, through steps towards analytical process improvement. Lean Six Sigma represents a form of scientific method type, which is empirical, inductive and deductive, and systematic, which relies on data, and is fact-based. The Lean Six Sigma methodology comprises five macro-phases, namely Define, Measure, Analyse, Improve and Control (DMAIC). Both qualitative and quantitative laboratory data were collected in terms of these phases. Qualitative data were collected by using quality-tools, namely an Ishikawa diagram, a Pareto chart, Kaizen analysis and a Failure Mode Effect analysis tool. Quantitative laboratory data, based on the analytical chemistry test method, were collected through a controlled experiment. The controlled experiment entailed 13 replicated runs of the selenium test method, whereby 11 samples were repetitively analysed, whilst Certified Reference Material (CRM) was also included in 6 of the runs. Laboratory results obtained from the controlled experiment was analysed by using statistical methods, commonly associated with quality validation of chemistry procedures. Analysis of both sets of data yielded an improved selenium analysis method, believed to provide greater reliability of results, in addition to a greatly reduced cycle time and superior control features. Lean Six Sigma may therefore be regarded as a valuable tool in any laboratory, and represents both a management discipline, and a standardised approach to problem solving and process optimisation.

Without Warning: Worker Deaths From Heat 2014-2016.

PubMed

Roelofs, Cora

2018-01-01

Worker deaths from heat exposure are unlike heat deaths in the general population; workers tend to be outside in variable temperatures and younger than sixty-five years. Climate change will increase the frequency, duration, and variability of hot temperatures. Public health warning systems, such as the Heat Index of the National Weather Service, do not generally account for workers' greater likelihood of exposure to direct sunlight or exertion. Only 28% of the 79 worker heat-related fatalities during 2014-2016 occurred on days when the National Weather Service warning would have included the possibility of fatal heat stroke. Common heat illness prevention advice ignores workers' lack of control over their ability to rest and seek cooler temperatures. Additionally, acclimatization, or phased-in work in the heat, may be less useful given temperature variability under climate change. Workers' vulnerability and context of heat exposure should inform public health surveillance and response to prevent heat illness and death.

A comparison of electronic heterodyne moire deflectometry and electronic heterodyne holographic interferometry for flow measurements

NASA Technical Reports Server (NTRS)

Decker, A. J.; Stricker, J.

1985-01-01

Electronic heterodyne moire deflectometry and electronic heterodyne holographic interferometry are compared as methods for the accurate measurement of refractive index and density change distributions of phase objects. Experimental results are presented to show that the two methods have comparable accuracy for measuring the first derivative of the interferometric fringe shift. The phase object for the measurements is a large crystal of KD*P, whose refractive index distribution can be changed accurately and repeatably for the comparison. Although the refractive index change causes only about one interferometric fringe shift over the entire crystal, the derivative shows considerable detail for the comparison. As electronic phase measurement methods, both methods are very accurate and are intrinsically compatible with computer controlled readout and data processing. Heterodyne moire is relatively inexpensive and has high variable sensitivity. Heterodyne holographic interferometry is better developed, and can be used with poor quality optical access to the experiment.

Blood lipids, homocysteine, stress factors, and vitamins in clinically stable multiple sclerosis patients

PubMed Central

2010-01-01

Multiple Sclerosis (MS) patients present a decrease of antioxidants and neuroprotective and immunoregulatory vitamins and an increase of total homocysteine (tHcy), cholesterol (CHL), HDL-cholesterol, and of cellular stress markers, variably associated with the different phases of the disease. We compared the blood levels of uric acid, folic acid, vitamins B12, A, and E, tHcy, CHL, HDL-cholesterol, and triglycerides in forty MS patients during a phase of clinical inactivity with those of eighty healthy controls, matched for age and sex. We found higher levels of tHcy (p = 0.032) and of HDL-cholesterol (p = 0.001) and lower levels of vitamin E (p = 0.001) and the ratio vitamin E/CHL (p = 0.001) in MS patients. In conclusion, modifications of some biochemical markers of cell damage were detected in MS patients during a phase of clinical inactivity. PMID:20163740

The Implications of Encoder/Modulator/ Phased Array Designs for Future Broadband LEO Communications

NASA Technical Reports Server (NTRS)

Vanderaar, Mark; Jensen, Chris A.; Terry, John D.

1997-01-01

In this paper we summarize the effects of modulation and channel coding on the design of wide angle scan, broadband, phased army antennas. In the paper we perform several trade studies. First, we investigate the amplifier back-off requirement as a function of variability of modulation envelope. Specifically, we contrast constant and non-constant envelope modulations, as well as single and multiple carrier schemes. Additionally, we address the issues an(f concerns of using pulse shaping filters with the above modulation types. Second, we quantify the effects of beam steering on the quality of data, recovery using selected modulation techniques. In particular, we show that the frequency response of the array introduces intersymbol interference for broadband signals and that the mode of operation for the beam steering controller may introduce additional burst or random errors. Finally, we show that the encoder/modulator design must be performed in conjunction with the phased array antenna design.

Grassmann phase space theory and the Jaynes-Cummings model

NASA Astrophysics Data System (ADS)

Dalton, B. J.; Garraway, B. M.; Jeffers, J.; Barnett, S. M.

2013-07-01

The Jaynes-Cummings model of a two-level atom in a single mode cavity is of fundamental importance both in quantum optics and in quantum physics generally, involving the interaction of two simple quantum systems—one fermionic system (the TLA), the other bosonic (the cavity mode). Depending on the initial conditions a variety of interesting effects occur, ranging from ongoing oscillations of the atomic population difference at the Rabi frequency when the atom is excited and the cavity is in an n-photon Fock state, to collapses and revivals of these oscillations starting with the atom unexcited and the cavity mode in a coherent state. The observation of revivals for Rydberg atoms in a high-Q microwave cavity is key experimental evidence for quantisation of the EM field. Theoretical treatments of the Jaynes-Cummings model based on expanding the state vector in terms of products of atomic and n-photon states and deriving coupled equations for the amplitudes are a well-known and simple method for determining the effects. In quantum optics however, the behaviour of the bosonic quantum EM field is often treated using phase space methods, where the bosonic mode annihilation and creation operators are represented by c-number phase space variables, with the density operator represented by a distribution function of these variables. Fokker-Planck equations for the distribution function are obtained, and either used directly to determine quantities of experimental interest or used to develop c-number Langevin equations for stochastic versions of the phase space variables from which experimental quantities are obtained as stochastic averages. Phase space methods have also been developed to include atomic systems, with the atomic spin operators being represented by c-number phase space variables, and distribution functions involving these variables and those for any bosonic modes being shown to satisfy Fokker-Planck equations from which c-number Langevin equations are often developed. However, atomic spin operators satisfy the standard angular momentum commutation rules rather than the commutation rules for bosonic annihilation and creation operators, and are in fact second order combinations of fermionic annihilation and creation operators. Though phase space methods in which the fermionic operators are represented directly by c-number phase space variables have not been successful, the anti-commutation rules for these operators suggest the possibility of using Grassmann variables—which have similar anti-commutation properties. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of phase space methods in quantum optics to treat fermionic systems by representing fermionic annihilation and creation operators directly by Grassmann phase space variables is rather rare. This paper shows that phase space methods using a positive P type distribution function involving both c-number variables (for the cavity mode) and Grassmann variables (for the TLA) can be used to treat the Jaynes-Cummings model. Although it is a Grassmann function, the distribution function is equivalent to six c-number functions of the two bosonic variables. Experimental quantities are given as bosonic phase space integrals involving the six functions. A Fokker-Planck equation involving both left and right Grassmann differentiations can be obtained for the distribution function, and is equivalent to six coupled equations for the six c-number functions. The approach used involves choosing the canonical form of the (non-unique) positive P distribution function, in which the correspondence rules for the bosonic operators are non-standard and hence the Fokker-Planck equation is also unusual. Initial conditions, such as those above for initially uncorrelated states, are discussed and used to determine the initial distribution function. Transformations to new bosonic variables rotating at the cavity frequency enable the six coupled equations for the new c-number functions-that are also equivalent to the canonical Grassmann distribution function-to be solved analytically, based on an ansatz from an earlier paper by Stenholm. It is then shown that the distribution function is exactly the same as that determined from the well-known solution based on coupled amplitude equations. In quantum-atom optics theories for many atom bosonic and fermionic systems are needed. With large atom numbers, treatments must often take into account many quantum modes—especially for fermions. Generalisations of phase space distribution functions of phase space variables for a few modes to phase space distribution functionals of field functions (which represent the field operators, c-number fields for bosons, Grassmann fields for fermions) are now being developed for large systems. For the fermionic case, the treatment of the simple two mode problem represented by the Jaynes-Cummings model is a useful test case for the future development of phase space Grassmann distribution functional methods for fermionic applications in quantum-atom optics.

Acute effects of static stretching on passive stiffness and postural balance in healthy, elderly men.

PubMed

Palmer, Ty B; Agu-Udemba, Chinonye C; Palmer, Bailey M

2018-02-01

This study aimed to examine the acute effects of straight-leg raise (SLR) static stretching on passive stiffness and postural balance in healthy, elderly men. An additional aim of this study was to examine the relationships between stiffness and balance at baseline (prior to stretching) and the relationships between the stretch-induced changes in these variables. Eleven elderly men (age = 69 ± 6 years; height = 177 ± 7 cm; mass = 83 ± 13 kg) underwent postural balance and passive stiffness assessments before and after: 1) a stretching treatment consisting of four, 15-s SLR static stretches performed by the primary investigator and 2) a control treatment consisting of no static stretching. Passive stiffness was calculated from the slopes of the initial (phase 1) and final (phase 2) portions of the angle-torque curve. Unilateral postural balance was assessed on the right leg using a commercially designed balance testing device, which provides a measurement of static stability based on the overall stability index (OSI). The slope coefficients and OSI values decreased from pre- to post-treatment for the stretching intervention (P = 0.015 and 0.018, respectively); however, there were no changes for the control (P = 0.654 and 0.920). For the stretching intervention, a significant positive relationship was observed between OSI and the slope coefficient of phase 1 at baseline (r = 0.619; P = 0.042). A significant positive relationship was also observed between the stretched-induced changes in OSI and the slope coefficient of phase 1 (r = 0.731; P = 0.011). No relationship was observed between OSI and the slope coefficient of phase 2 at baseline (r = 0.262; P = 0.437) nor was there a relationship between the changes in these variables (r = 0.419; P = 0.200). A short, practical bout of SLR static stretching may be an effective intervention for reducing passive stiffness and improving postural balance in healthy, elderly men.

Towards an automatic statistical model for seasonal precipitation prediction and its application to Central and South Asian headwater catchments

NASA Astrophysics Data System (ADS)

Gerlitz, Lars; Gafurov, Abror; Apel, Heiko; Unger-Sayesteh, Katy; Vorogushyn, Sergiy; Merz, Bruno

2016-04-01

Statistical climate forecast applications typically utilize a small set of large scale SST or climate indices, such as ENSO, PDO or AMO as predictor variables. If the predictive skill of these large scale modes is insufficient, specific predictor variables such as customized SST patterns are frequently included. Hence statistically based climate forecast models are either based on a fixed number of climate indices (and thus might not consider important predictor variables) or are highly site specific and barely transferable to other regions. With the aim of developing an operational seasonal forecast model, which is easily transferable to any region in the world, we present a generic data mining approach which automatically selects potential predictors from gridded SST observations and reanalysis derived large scale atmospheric circulation patterns and generates robust statistical relationships with posterior precipitation anomalies for user selected target regions. Potential predictor variables are derived by means of a cellwise correlation analysis of precipitation anomalies with gridded global climate variables under consideration of varying lead times. Significantly correlated grid cells are subsequently aggregated to predictor regions by means of a variability based cluster analysis. Finally for every month and lead time, an individual random forest based forecast model is automatically calibrated and evaluated by means of the preliminary generated predictor variables. The model is exemplarily applied and evaluated for selected headwater catchments in Central and South Asia. Particularly the for winter and spring precipitation (which is associated with westerly disturbances in the entire target domain) the model shows solid results with correlation coefficients up to 0.7, although the variability of precipitation rates is highly underestimated. Likewise for the monsoonal precipitation amounts in the South Asian target areas a certain skill of the model could be detected. The skill of the model for the dry summer season in Central Asia and the transition seasons over South Asia is found to be low. A sensitivity analysis by means on well known climate indices reveals the major large scale controlling mechanisms for the seasonal precipitation climate of each target area. For the Central Asian target areas, both, the El Nino Southern Oscillation and the North Atlantic Oscillation are identified as important controlling factors for precipitation totals during moist spring season. Drought conditions are found to be triggered by a warm ENSO phase in combination with a positive phase of the NAO. For the monsoonal summer precipitation amounts over Southern Asia, the model suggests a distinct negative response to El Nino events.

Prevention of Trauma/Hemorrhagic Shock-Induced Mortality,Apoptosis, Inflammation and Mitochondrial Dysfunction

DTIC Science & Technology

2013-12-01

suggesting another mechanism for the apoptosis-reduction benefit of IL-6 signaling, and 7) Stat3. can substitute for Stat3. to restore mitochondrial...Rats subjected to femur fracture and T-HS (AIM 2) and 3) Swine subjected to laparotomy, splenectomy, tissue injury and controlled HS (AIM 3). Aim...unacceptable mortality during the shock phase, the second was that there was variable amounts of bleeding from the femoral fracture site. We opted based on

Crustal thickness control on Sr/Y signatures of recent arc magmas: an Earth scale perspective

PubMed Central

Chiaradia, Massimo

2015-01-01

Arc magmas originate in subduction zones as partial melts of the mantle, induced by aqueous fluids/melts liberated by the subducted slab. Subsequently, they rise through and evolve within the overriding plate crust. Aside from broadly similar features that distinguish them from magmas of other geodynamic settings (e.g., mid-ocean ridges, intraplate), arc magmas display variably high Sr/Y values. Elucidating the debated origin of high Sr/Y signatures in arc magmas, whether due to mantle-source, slab melting or intracrustal processes, is instrumental for models of crustal growth and ore genesis. Here, using a statistical treatment of >23000 whole rock geochemical data, I show that average Sr/Y values and degree of maturation (MgO depletion at peak Sr/Y values) of 19 out of 22 Pliocene-Quaternary arcs correlate positively with arc thickness. This suggests that crustal thickness exerts a first order control on the Sr/Y variability of arc magmas through the stabilization or destabilization of mineral phases that fractionate Sr (plagioclase) and Y (amphibole ± garnet). In fact, the stability of these mineral phases is function of the pressure at which magma evolves, which depends on crustal thickness. The data presented show also that high Sr/Y Pliocene-Quaternary intermediate-felsic arc rocks have a distinct origin from their Archean counterparts. PMID:25631193

Finger tapping and pre-attentive sensorimotor timing in adults with ADHD.

PubMed

Hove, Michael J; Gravel, Nickolas; Spencer, Rebecca M C; Valera, Eve M

2017-12-01

Sensorimotor timing deficits are considered central to attention-deficit/hyperactivity disorder (ADHD). However, the tasks establishing timing impairments often involve interconnected processes, including low-level sensorimotor timing and higher level executive processes such as attention. Thus, the source of timing deficits in ADHD remains unclear. Low-level sensorimotor timing can be isolated from higher level processes in a finger-tapping task that examines the motor response to unexpected shifts of metronome onsets. In this study, adults with ADHD and ADHD-like symptoms (n = 25) and controls (n = 26) performed two finger-tapping tasks. The first assessed tapping variability in a standard tapping task (metronome-paced and unpaced). In the other task, participants tapped along with a metronome that contained unexpected shifts (±15, 50 ms); the timing adjustment on the tap following the shift captures pre-attentive sensorimotor timing (i.e., phase correction) and thus should be free of potential higher order confounds (e.g., attention). In the standard tapping task, as expected, the ADHD group had higher timing variability in both paced and unpaced tappings. However, in the pre-attentive task, performance did not differ between the ADHD and control groups. Together, results suggest that low-level sensorimotor timing and phase correction are largely preserved in ADHD and that some timing impairments observed in ADHD may stem from higher level factors (such as sustained attention).

Cognitive Analytic Therapy for Bipolar Disorder: A Pilot Randomized Controlled Trial.

PubMed

Evans, Mark; Kellett, Stephen; Heyland, Simon; Hall, Jo; Majid, Shazmin

2017-01-01

The evidence base for treatment of bipolar affective disorder (BD) demands the evaluation of new psychotherapies in order to broaden patient choice. This study reports on the feasibility, safety, helpfulness and effectiveness of cognitive analytic therapy (CAT). In a pilot randomized controlled trial, BD patients in remission were randomized to either receiving 24 sessions of CAT (n = 9) or treatment as usual (n = 9) and were assessed in terms of symptoms, functioning and service usage over time. In the CAT arm no adverse events occurred, 8/9 completed treatment, 5/8 attended all 24 sessions and 2/8 were categorized as recovered. The most common helpful event during CAT was recognition of patterns in mood variability, with helpfulness themes changing according to phase of therapy. No major differences were found when comparing the arms over time in terms of service usage or psychometric outcomes. The study suggests that conducting further research into the effectiveness of CAT in treating BD is warranted and guidance regarding future trials is provided. Copyright © 2016 John Wiley & Sons, Ltd. Treating BD with CAT appears feasible and safe. Retaining fidelity to the reformulation, recognition and revision structure of CAT appears useful. Participants stated that across the phases of CAT, focussing on patterns of mood variability was consistently helpful. Copyright © 2016 John Wiley & Sons, Ltd.

Phonation interval modification and speech performance quality during fluency-inducing conditions by adults who stutter

PubMed Central

Ingham, Roger J.; Bothe, Anne K.; Wang, Yuedong; Purkhiser, Krystal; New, Anneliese

2012-01-01

Purpose To relate changes in four variables previously defined as characteristic of normally fluent speech to changes in phonatory behavior during oral reading by persons who stutter (PWS) and normally fluent controls under multiple fluency-inducing (FI) conditions. Method Twelve PWS and 12 controls each completed 4 ABA experiments. During A phases, participants read normally. B phases were 4 different FI conditions: auditory masking, chorus reading, whispering, and rhythmic stimulation. Dependent variables were the durations of accelerometer-recorded phonated intervals; self-judged speech effort; and observer-judged stuttering frequency, speech rate, and speech naturalness. The method enabled a systematic replication of Ingham et al. (2009). Results All FI conditions resulted in decreased stuttering and decreases in the number of short phonated intervals, as compared with baseline conditions, but the only FI condition that satisfied all four characteristics of normally fluent speech was chorus reading. Increases in longer phonated intervals were associated with decreased stuttering but also with poorer naturalness and/or increased speech effort. Previous findings concerning the effects of FI conditions on speech naturalness and effort were replicated. Conclusions Measuring all relevant characteristics of normally fluent speech, in the context of treatments that aim to reduce the occurrence of short-duration PIs, may aid the search for an explanation of the nature of stuttering and may also maximize treatment outcomes for adults who stutter. PMID:22365886

A new high pressure sapphire nuclear magnetic resonance cell

NASA Astrophysics Data System (ADS)

Bai, Shi; Taylor, Craig M.; Mayne, Charles L.; Pugmire, Ronald J.; Grant, David M.

1996-01-01

A new version of a single-crystal sapphire high pressure nuclear magnetic resonance (NMR) cell is described that is capable of controlling the sample pressure independent of the temperature. A movable piston inside the cell adjusts and controls the sample pressure from ambient conditions to 200 atm within ±0.3 atm. The linewidth at half-height for a 13C spectrum of carbon dioxide at 15 °C and 57.8 atm is found to be 0.5 Hz. The carbon dioxide gas/liquid phase transition is clearly observed by measuring 13C chemical shifts as the sample pressure approaches equilibrium. The time required for this NMR cell to reach equilibrium with its surroundings is relatively short, usually 15-30 min. The cell body has the same outer dimensions of a standard spinning turbine and fits into a standard 10 mm commercial probehead capable of controlling the sample temperature using the spectrometer's variable temperature unit. The flexibility of the device and the increased speed in making the measurement is demonstrated. Such control of important thermodynamic variables facilitates the NMR study of important biochemical and chemical reactions in gas, liquid, and supercritical fluid environments.

Dynamic knee joint mechanics after anterior cruciate ligament reconstruction.

PubMed

Clarke, Sarah B; Kenny, Ian C; Harrison, Andrew J

2015-01-01

There is scarcity of information on the long-term adaptations in lower limb biomechanics during game-specific movements after anterior cruciate ligament (ACL) reconstruction. Particularly, variables such as knee abduction moments and transverse plane knee motion have not been studied during a game-specific landing and cutting task after ACL reconstruction. The purpose of this study was to compare the hip and knee mechanics between the ACL-reconstructed (ACLr) group and a healthy control group. Thirty-eight reconstructed athletes (18 ACLr, 18 control) participated in the study. Three-dimensional hip, knee, and ankle angles were calculated during a maximal drop jump land from a 0.30-m box and unanticipated cutting task at 45°. During the landing phase, ACLr participants had increased hip flexion (P < 0.003) and transverse plane knee range of motion (P = 0.027). During the cutting phase, the ACLr participant's previously injured limb had increased internal knee abduction moment compared with that of the control group (P = 0.032). No significant differences were reported between the previously injured and contralateral uninjured limb. Previously injured participants demonstrated higher knee abduction moment and transverse plane range of motion when compared with those of control participants during a game-specific landing and cutting task.

Water Polo Game-Related Statistics in Women’s International Championships: Differences and Discriminatory Power

PubMed Central

Escalante, Yolanda; Saavedra, Jose M.; Tella, Victor; Mansilla, Mirella; García-Hermoso, Antonio; Dominguez, Ana M.

2012-01-01

The aims of this study were (i) to compare women’s water polo game-related statistics by match outcome (winning and losing teams) and phase (preliminary, classificatory, and semi-final/bronze medal/gold medal), and (ii) identify characteristics that discriminate performances for each phase. The game-related statistics of the 124 women’s matches played in five International Championships (World and European Championships) were analyzed. Differences between winning and losing teams in each phase were determined using the chi-squared. A discriminant analysis was then performed according to context in each of the three phases. It was found that the game-related statistics differentiate the winning from the losing teams in each phase of an international championship. The differentiating variables were both offensive (centre goals, power-play goals, counterattack goal, assists, offensive fouls, steals, blocked shots, and won sprints) and defensive (goalkeeper-blocked shots, goalkeeper-blocked inferiority shots, and goalkeeper-blocked 5-m shots). The discriminant analysis showed the game-related statistics to discriminate performance in all phases: preliminary, classificatory, and final phases (92%, 90%, and 83%, respectively). Two variables were discriminatory by match outcome (winning or losing teams) in all three phases: goals and goalkeeper-blocked shots. Key pointsThe preliminary phase that more than one variable was involved in this differentiation, including both offensive and defensive aspects of the game.The game-related statistics were found to have a high discriminatory power in predicting the result of matches with shots and goalkeeper-blocked shots being discriminatory variables in all three phases.Knowledge of the characteristics of women’s water polo game-related statistics of the winning teams and their power to predict match outcomes will allow coaches to take these characteristics into account when planning training and match preparation. PMID:24149356

Early 20th Century Arctic Warming Intensified by Pacific and Atlantic Multidecadal Variability

NASA Astrophysics Data System (ADS)

Tokinaga, H.; Xie, S. P.; Mukougawa, H.

2017-12-01

We investigate the influence of Pacific and Atlantic multidecadal variability on the Arctic temperature, with a particular focus on the early 20th century Arctic warming. Arctic surface air temperature increased rapidly over the early 20th century, at rates comparable to those of recent decades despite much weaker greenhouse gas forcing than at present. We find that the concurrent phase shift of Pacific and Atlantic multidecadal variability is the major driver for the early 20th century Arctic warming. Atmospheric model simulations reproduce the early Arctic warming when the interdecadal variability of sea surface temperature (SST) is properly prescribed. The early Arctic warming is associated with the cold-to-warm phase shifts of Atlantic and Pacific multidecadal variability modes, a SST pattern reminiscent of the positive phase of the Pacific decadal and Atlantic multidecadal oscillations. The extratropical North Atlantic and North Pacific SST warming strengthens surface westerly winds over northern Eurasia, intensifying the warming there. The equatorial Pacific warming deepens the Aleutian low, advecting warm air to the North American Arctic. Coupled ocean-atmosphere simulations support the constructive intensification of Arctic warming by a concurrent, cold-to-warm phase shift of the Pacific and Atlantic multidecadal variability. Our results aid attributing the historical Arctic warming and thereby constrain the amplified warming projected for this important region.

Adaptation to abrupt time shifts of the oscillator(s) controlling human circadian rhythms.

PubMed Central

Mills, J N; Minors, D S; Waterhouse, J M

1978-01-01

1. Thirty-six subjects in an isolation unit were subjected to time shifts of 12 hr, or of 8 hr in either direction. 2. The rhythms of body temperature and excretion of eight urinary constituents were studied before and after the shift, both on a usual nychthemeral routine and during 24 hr when they remained under constant conditions, awake, engaged in light, mainly sedentary activity, and consuming identical food and fluid every hour. 3. The rhythms on nychthemeral routine were defined by fitting cosine curves. On constant routine the rhythm after the shift was cross-correlated with the original rhythm, either with variable delay (or advance) or with an additive mixture between this variably shifted rhythm and the unshifted or a fully shifted rhythm. The process yielding the highest correlation coefficient was accepted as the best descriptor of the nature of adaptation. 4. A combination of two rhythms was observed more often for urinary sodium, chloride and phosphate than for other variables. 5. Adaptation appeared to have proceeded further after westward than eastward shifts, and this difference was particularly noticeable for urinary potassium, sodium and chloride. 6. Partial adaptation usually involved a phase delay, even after an eastward shift when a cumulative delay of 16 hr would be needed to achieve full adaptation and re-entrainment. 7. Observations under nychthemeral conditions often gave a false idea of the degree of adaptation. In particular, after an eastward shift the phase of the rhythms appeared to shift in the appropriate direction when studied under nychthemeral conditions whereas the endogenous oscillator either showed no consistent behaviour or, in the control of urate excretion, a shift in the wrong direction. 8. The implications for people undergoing time shifts, in the course of shift work or transmeridional flights, are indicated. PMID:745108

Gait analysis following treadmill training with body weight support versus conventional physical therapy: a prospective randomized controlled single blind study.

PubMed

Lucareli, P R; Lima, M O; Lima, F P S; de Almeida, J G; Brech, G C; D'Andréa Greve, J M

2011-09-01

Single-blind randomized, controlled clinical study. To evaluate, using kinematic gait analysis, the results obtained from gait training on a treadmill with body weight support versus those obtained with conventional gait training and physiotherapy. Thirty patients with sequelae from traumatic incomplete spinal cord injuries at least 12 months earlier; patients were able to walk and were classified according to motor function as ASIA (American Spinal Injury Association) impairment scale C or D. Patients were divided randomly into two groups of 15 patients by the drawing of opaque envelopes: group A (weight support) and group B (conventional). After an initial assessment, both groups underwent 30 sessions of gait training. Sessions occurred twice a week, lasted for 30 min each and continued for four months. All of the patients were evaluated by a single blinded examiner using movement analysis to measure angular and linear kinematic gait parameters. Six patients (three from group A and three from group B) were excluded because they attended fewer than 85% of the training sessions. There were no statistically significant differences in intra-group comparisons among the spatial-temporal variables in group B. In group A, the following significant differences in the studied spatial-temporal variables were observed: increases in velocity, distance, cadence, step length, swing phase and gait cycle duration, in addition to a reduction in stance phase. There were also no significant differences in intra-group comparisons among the angular variables in group B. However, group A achieved significant improvements in maximum hip extension and plantar flexion during stance. Gait training with body weight support was more effective than conventional physiotherapy for improving the spatial-temporal and kinematic gait parameters among patients with incomplete spinal cord injuries.

Mild traumatic brain injury: graph-model characterization of brain networks for episodic memory.

PubMed

Tsirka, Vasso; Simos, Panagiotis G; Vakis, Antonios; Kanatsouli, Kassiani; Vourkas, Michael; Erimaki, Sofia; Pachou, Ellie; Stam, Cornelis Jan; Micheloyannis, Sifis

2011-02-01

Episodic memory is among the cognitive functions that can be affected in the acute phase following mild traumatic brain injury (MTBI). The present study used EEG recordings to evaluate global synchronization and network organization of rhythmic activity during the encoding and recognition phases of an episodic memory task varying in stimulus type (kaleidoscope images, pictures, words, and pseudowords). Synchronization of oscillatory activity was assessed using a linear and nonlinear connectivity estimator and network analyses were performed using algorithms derived from graph theory. Twenty five MTBI patients (tested within days post-injury) and healthy volunteers were closely matched on demographic variables, verbal ability, psychological status variables, as well as on overall task performance. Patients demonstrated sub-optimal network organization, as reflected by changes in graph parameters in the theta and alpha bands during both encoding and recognition. There were no group differences in spectral energy during task performance or on network parameters during a control condition (rest). Evidence of less optimally organized functional networks during memory tasks was more prominent for pictorial than for verbal stimuli. Copyright © 2010 Elsevier B.V. All rights reserved.

Influence of the Formulation Parameters on the Particle Size and Encapsulation Efficiency of Resveratrol in PLA and PLA-PEG Blend Nanoparticles: A Factorial Design.

PubMed

Lindner, Gabriela da Rocha; Dalmolin, Luciana Facco; Khalil, Najeh Maissar; Mainardes, Rubiana Mara

2015-12-01

Polymeric nanoparticles are colloidal systems that promote protection and modification of physicochemical characteristics of a drug and that also ensure controlled and extended drug release. This paper reports a 2(3) factorial design study to optimize poly(lactide) (PLA) and poly(lactide)-polyethylene glycol (PLA-PEG) blend nanoparticles containing resveratrol (RVT) for prolonged release. The independent variables analyzed were solvent composition, surfactant concentration and ratio of aqueous to organic phase (two levels each factor). Mean particle size and RVT encapsulation efficiency were set as the dependent variables. The selected optimized parameters were set as organic phase comprised of a mixture of dichloromethane and ethyl acetate, 1% of surfactant polyvinyl alcohol and a 3:1 ratio of aqueous to organic phase, for both PLA and PLA-PEG blend nanoparticles. This formulation originated nanoparticles with size of 228 ± 10 nm and 185 ± 70 nm and RVT encapsulation efficiency of 82 ± 10% and 76 ± 7% for PLA and PLA-PEG blend nanoparticles, respectively. The in vitro release study showed a biphasic pattern with prolonged RVT release and PEG did not influence the RVT release. The in vitro release data were in favor of Higuchi-diffusion kinetics for both nanoformulations and the Kossmeyer-Peppas coefficient indicated that anomalous transport was the main release mechanism of RVT. PLA and PLA-PEG blend nanoparticles produced with single emulsion-solvent evaporation technology were found to be a promising approach for the incorporation of RVT and promoted its controlled release. The factorial design is a tool of great value in choosing formulations with optimized parameters.

Upregulation of Zinc Absorption Matches Increases in Physiologic Requirements for Zinc in Women Consuming High- or Moderate-Phytate Diets during Late Pregnancy and Early Lactation.

PubMed

Hambidge, K Michael; Miller, Leland V; Mazariegos, Manolo; Westcott, Jamie; Solomons, Noel W; Raboy, Victor; Kemp, Jennifer F; Das, Abhik; Goco, Norman; Hartwell, Ty; Wright, Linda; Krebs, Nancy F

2017-06-01

Background: Estimated physiologic requirements (PRs) for zinc increase in late pregnancy and early lactation, but the effect on dietary zinc requirements is uncertain. Objective: The aim of this study was to determine changes in daily fractional absorbed zinc and total absorbed zinc (TAZ) from ad libitum diets of differing phytate contents in relation to physiologic zinc requirements during pregnancy and lactation. Methods: This was a prospective observational study of zinc absorption at 8 (phase 1) and 34 (phase 2) wk of gestation and 2 (phase 3) and 6 (phase 4) mo of lactation. Participants were indigenous Guatemalan women of childbearing age whose major food staple was maize and who had been randomly assigned in a larger study to either of 2 ad libitum feeding groups: low-phytate maize (LP; 1.6 mg/g; n = 14) or control maize (C; 7.1 mg/g; n = 8). Total dietary zinc (milligrams per day, TDZ) and phytate (milligrams per day) were determined from duplicate diets and fractional absorption (FAZ) by dual isotope ratio technique (TAZ = TDZ × FAZ). All variables were examined longitudinally and by group and compared with PRs. TAZ values at later phases were compared with phase 1. Measured TAZ was compared with predicted TAZ for nonpregnant, nonlactating (NPNL) women. Results: TAZ was greater in the LP group than in the C group at all phases. All variables increased from phase 1 to phases 2 and 3 and declined at phase 4. TAZ increased by 1.25 mg/d ( P = 0.045) in the C group and by 0.81 mg/d ( P = 0.058) in the LP group at phase 2. At phase 3, the increases were 2.66 mg/d ( P = 0.002) in the C group and 2.28 mg/d ( P = 0.0004) in the LP group, compared with a 1.37-mg/d increase in PR. Measured TAZ was greater than predicted values in phases 2-4. Conclusions: Upregulation of zinc absorption in late pregnancy and early lactation matches increases in PRs of pregnant and lactating women, regardless of dietary phytate, which has implications for dietary zinc requirements of pregnant and lactating women. © 2017 American Society for Nutrition.

Programming and execution of movement in Parkinson's disease.

PubMed

Sheridan, M R; Flowers, K A; Hurrell, J

1987-10-01

Programming and execution of arm movements in Parkinson's disease were investigated in choice and simple reaction time (RT) situations in which subjects made aimed movements at a target. A no-aiming condition was also studied. Reaction time was fractionated using surface EMG recording into premotor (central) and motor (peripheral) components. Premotor RT was found to be greater for parkinsonian patients than normal age-matched controls in the simple RT condition, but not in the choice condition. This effect did not depend on the parameters of the impending movement. Thus, paradoxically, parkinsonian patients were not inherently slower at initiating aiming movements from the starting position, but seemed unable to use advance information concerning motor task demands to speed up movement initiation. For both groups, low velocity movements took longer to initiate than high velocity ones. In the no-aiming condition parkinsonian RTs were markedly shorter than when aiming, but were still significantly longer than control RTs. Motor RT was constant across all conditions and was not different for patient and control subjects. In all conditions, parkinsonian movements were around 37% slower than control movements, and their movement times were more variable, the differences showing up early on in the movement, that is, during the initial ballistic phase. The within-subject variability of movement endpoints was also greater in patients. The motor dysfunction displayed in Parkinson's disease involves a number of components: (1) a basic central problem with simply initiating movements, even when minimal programming is required (no-aiming condition); (2) difficulty in maintaining computed forces for motor programs over time (simple RT condition); (3) a basic slowness of movement (bradykinesia) in all conditions; and (4) increased variability of movement in both time and space, presumably caused by inherent variability in force production.

The generalised isodamping approach for robust fractional PID controllers design

NASA Astrophysics Data System (ADS)

Beschi, M.; Padula, F.; Visioli, A.

2017-06-01

In this paper, we present a novel methodology to design fractional-order proportional-integral-derivative controllers. Based on the description of the controlled system by means of a family of linear models parameterised with respect to a free variable that describes the real process operating point, we design the controller by solving a constrained min-max optimisation problem where the maximum sensitivity has to be minimised. Among the imposed constraints, the most important one is the new generalised isodamping condition, that defines the invariancy of the phase margin with respect to the free parameter variations. It is also shown that the well-known classical isodamping condition is a special case of the new technique proposed in this paper. Simulation results show the effectiveness of the proposed technique and the superiority of the fractional-order controller compared to its integer counterpart.

Delta Ori Phase-Dependent Variability from Chandra and MOST Campaign

NASA Astrophysics Data System (ADS)

Nichols, Joy; Naze, Yael; Moffatt, Anthony F. J.; Corcoran, Michael; Richardson, Noel; Williams, S.; Pollock, A. M. T.; Ignace, Richard; Hole, T.; Waldron, W.; Evans, Nancy Remage; MOST Collaboration

2013-06-01

We report preliminary results from variability analysis of delta Ori in Chandra high-resolution X-ray spectroscopy and concurrent MOST high-precision optical photometry. With nearly complete phase coverage of the 5-day eclipsing binary orbit, it is possible to measure directly radial velocity and flux variations as a function of phase, leading to a mapping of the stellar wind distribution for the massive primary star. The phase dependence of the X-ray overall intensity and the comparative behavior of the emission lines are also presented.

Predictive Variables of Half-Marathon Performance for Male Runners

PubMed Central

Gómez-Molina, Josué; Ogueta-Alday, Ana; Camara, Jesus; Stickley, Christoper; Rodríguez-Marroyo, José A.; García-López, Juan

2017-01-01

The aims of this study were to establish and validate various predictive equations of half-marathon performance. Seventy-eight half-marathon male runners participated in two different phases. Phase 1 (n = 48) was used to establish the equations for estimating half-marathon performance, and Phase 2 (n = 30) to validate these equations. Apart from half-marathon performance, training-related and anthropometric variables were recorded, and an incremental test on a treadmill was performed, in which physiological (VO2max, speed at the anaerobic threshold, peak speed) and biomechanical variables (contact and flight times, step length and step rate) were registered. In Phase 1, half-marathon performance could be predicted to 90.3% by variables related to training and anthropometry (Equation 1), 94.9% by physiological variables (Equation 2), 93.7% by biomechanical parameters (Equation 3) and 96.2% by a general equation (Equation 4). Using these equations, in Phase 2 the predicted time was significantly correlated with performance (r = 0.78, 0.92, 0.90 and 0.95, respectively). The proposed equations and their validation showed a high prediction of half-marathon performance in long distance male runners, considered from different approaches. Furthermore, they improved the prediction performance of previous studies, which makes them a highly practical application in the field of training and performance. Key points The present study obtained four equations involving anthropometric, training, physiological and biomechanical variables to estimate half-marathon performance. These equations were validated in a different population, demonstrating narrows ranges of prediction than previous studies and also their consistency. As a novelty, some biomechanical variables (i.e. step length and step rate at RCT, and maximal step length) have been related to half-marathon performance. PMID:28630571

Phase Synchronization in Electroencephalographic Recordings Prognosticates Outcome in Paediatric Coma

PubMed Central

Nenadovic, Vera; Perez Velazquez, Jose Luis; Hutchison, James Saunders

2014-01-01

Brain injury from trauma, cardiac arrest or stroke is the most important cause of death and acquired disability in the paediatric population. Due to the lifetime impact of brain injury, there is a need for methods to stratify patient risk and ultimately predict outcome. Early prognosis is fundamental to the implementation of interventions to improve recovery, but no clinical model as yet exists. Healthy physiology is associated with a relative high variability of physiologic signals in organ systems. This was first evaluated in heart rate variability research. Brain variability can be quantified through electroencephalographic (EEG) phase synchrony. We hypothesised that variability in brain signals from EEG recordings would correlate with patient outcome after brain injury. Lower variability in EEG phase synchronization, would be associated with poor patient prognosis. A retrospective study, spanning 10 years (2000–2010) analysed the scalp EEGs of children aged 1 month to 17 years in coma (Glasgow Coma Scale, GCS, <8) admitted to the paediatric critical care unit (PCCU) following brain injury from TBI, cardiac arrest or stroke. Phase synchrony of the EEGs was evaluated using the Hilbert transform and the variability of the phase synchrony calculated. Outcome was evaluated using the 6 point Paediatric Performance Category Score (PCPC) based on chart review at the time of hospital discharge. Outcome was dichotomized to good outcome (PCPC score 1 to 3) and poor outcome (PCPC score 4 to 6). Children who had a poor outcome following brain injury secondary to cardiac arrest, TBI or stroke, had a higher magnitude of synchrony (R index), a lower spatial complexity of the synchrony patterns and a lower temporal variability of the synchrony index values at 15 Hz when compared to those patients with a good outcome. PMID:24752289

Investigation on the Inertance Tubes of Pulse Tube Cryocooler Without Reservoir

NASA Astrophysics Data System (ADS)

Liu, Y. J.; Yang, L. W.; Liang, J. T.; Hong, G. T.

2010-04-01

Phase angle is of vital importance for high-efficiency pulse tube cryocoolers (PTCs). Inertance tube as the main phase shifter is useful for the PTCs to obtain appropriate phase angle. Experiments of inertance tube without reservoir under variable frequency, variable length and diameter of inertance tube and variable pressure amplitude are investigated respectively. In addition, the authors used DeltaEC, a computer program to predict the performance of low-amplitude thermoacoustic engines, to simulate the effects of inertance tube without reservoir. According to the comparison of experiments and theoretical simulations, DeltaEC method is feasible and effective to direct and improve the design of inertance tubes.

Quantum-Enhanced Sensing Based on Time Reversal of Nonlinear Dynamics.

PubMed

Linnemann, D; Strobel, H; Muessel, W; Schulz, J; Lewis-Swan, R J; Kheruntsyan, K V; Oberthaler, M K

2016-07-01

We experimentally demonstrate a nonlinear detection scheme exploiting time-reversal dynamics that disentangles continuous variable entangled states for feasible readout. Spin-exchange dynamics of Bose-Einstein condensates is used as the nonlinear mechanism which not only generates entangled states but can also be time reversed by controlled phase imprinting. For demonstration of a quantum-enhanced measurement we construct an active atom SU(1,1) interferometer, where entangled state preparation and nonlinear readout both consist of parametric amplification. This scheme is capable of exhausting the quantum resource by detecting solely mean atom numbers. Controlled nonlinear transformations widen the spectrum of useful entangled states for applied quantum technologies.

Autonomous Dome for a Robotic Telescope

NASA Astrophysics Data System (ADS)

Kumar, A.; Sengupta, A.; Ganesh, S.

2016-12-01

The Physical Research Laboratory operates a 50 cm robotic observatory at Mount Abu (Rajsthan, India). This Automated Telescope for Variability Studies (ATVS) makes use of the Remote Telescope System 2 (RTS2) for autonomous operations. The observatory uses a 3.5 m dome from Sirius Observatories. We have developed electronics using Arduino electronic circuit boards with home grown logic and software to control the dome operations. We are in the process of completing the drivers to link our Arduino based dome controller with RTS2. This document is a short description of the various phases of the development and their integration to achieve the required objective.

Controlled assessment of the efficacy of occlusal stabilization splints on sleep bruxism.

PubMed

van der Zaag, Jacques; Lobbezoo, Frank; Wicks, Darrel J; Visscher, Corine M; Hamburger, Hans L; Naeije, Machiel

2005-01-01

To assess the efficacy of occlusal stabilization splints in the management of sleep bruxism (SB) in a double-blind, parallel, controlled, randomized clinical trial. Twenty-one participants were randomly assigned to an occlusal splint group (n = 11; mean age = 34.2 +/- 13.1 years) or a palatal splint (ie, an acrylic palatal coverage) group (n = 10; mean age = 34.9 +/- 11.2 years). Two polysomnographic recordings that included bilateral masseter electromyographic activity were made: one prior to treatment, the other after a treatment period of 4 weeks. The number of bruxism episodes per hour of sleep (Epi/h), the number of bursts per hour (Bur/h), and the bruxism time index (ie, the percentage of total sleep time spent bruxing) were established as outcome variables at a 10% maximum voluntary contraction threshold level. A general linear model was used to test both the effects between splint groups and within the treatment phase as well as their interaction for each outcome variable. Neither occlusal stabilization splints nor palatal splints had an influence on the SB outcome variables or on the sleep variables measured on a group level. In individual cases, variable outcomes were found: Some patients had an increase (33% to 48% of the cases), while others showed no change (33% to 48%) or a decrease (19% to 29%) in SB outcome variables. The absence of significant group effects of splints in the management of SB indicates that caution is required when splints are indicated, apart from their role in the protection against dental wear. The application of splints should therefore be considered at the individual patient level.

Hamiltonian Dynamics of Spider-Type Multirotor Rigid Bodies Systems

NASA Astrophysics Data System (ADS)

Doroshin, Anton V.

2010-03-01

This paper sets out to develop a spider-type multiple-rotor system which can be used for attitude control of spacecraft. The multirotor system contains a large number of rotor-equipped rays, so it was called a ``Spider-type System,'' also it can be called ``Rotary Hedgehog.'' These systems allow using spinups and captures of conjugate rotors to perform compound attitude motion of spacecraft. The paper describes a new method of spacecraft attitude reorientation and new mathematical model of motion in Hamilton form. Hamiltonian dynamics of the system is investigated with the help of Andoyer-Deprit canonical variables. These variables allow obtaining exact solution for hetero- and homoclinic orbits in phase space of the system motion, which are very important for qualitative analysis.

[The effects of hatha yoga exercises on stress and anxiety levels in mastectomized women].

PubMed

Bernardi, Marina Lima Daleprane; Amorim, Maria Helena Costa; Zandonade, Eliana; Santaella, Danilo Forghieri; Barbosa, Juliana de Assis Novais

2013-12-01

This article seeks to evaluate the effects of hatha yoga on stress and anxiety levels in mastectomized women. It also investigates the relationship between these levels with the following variables: age; marital status; religion; instruction; profession; smoke addiction; elitism; staging of the disease; and treatment phase. This involved controlled random clinical trial sampling of 45 mastectomized women treated at the Ilza Bianco outpatient service of Santa Rita de Cássia Hospital in the Brazilian state of Espírito Santo from March to November 2010. The experimental group participated in 6 individually-applied sessions with incentive for ongoing home practice and was re-evaluated after the period, whereas the control group was re-evaluated after a proportional period. For the study of the variables, the interview and recording on a form technique was used, along with the Anxiety Trait and State Test, and the Stress Symptoms and Signs Test. For statistical treatment, the Statistical Pack for Social Sciences was used. The data are statistically significant and have shown that hatha yoga exercises decrease stress and anxiety in the experimental group. No connection between confounding variables and anxiety and stress levels was found.

Effects of modified Pilates on variability of inter-joint coordination during walking in the elderly.

PubMed

Yoon, Sukhoon; Kim, Joo Nyeon; Lim, Hee Sung

2016-12-01

[Purpose] This study aimed to examine the effects of an 8-week modified Pilates program on the variability of inter-joint coordination in the elderly during walking. [Subjects and Methods] Twenty elderly participants with no recent history of orthopedic abnormalities (age, 67.9 ± 2.7 years; height, 163.7 ± 8.9 cm; weight, 67.1 ± 11.6 kg) were recruited for this study and randomly allocated to a modified Pilates exercise group or a control group. Three-dimensional motion analysis was performed on both groups to evaluate the effects of the Pilates exercise. [Results] There was no significant difference in the joint variability of the ankle, knee, and hip joints between the groups, both before training and after training. However, there was a significant increase in the hip-knee deviation phase value in the exercise group after the program was completed, and this increase was also significant when compared with that in the control group. [Conclusion] This study has demonstrated that an 8-week modified Pilates exercise program can have a positive impact on the gait of elderly participants, potentially by enhancing neuromuscular adjustment, which may have positive implications for reducing their fall risk.

Angle-adjustable density field formulation for the modeling of crystalline microstructure

NASA Astrophysics Data System (ADS)

Wang, Zi-Le; Liu, Zhirong; Huang, Zhi-Feng

2018-05-01

A continuum density field formulation with particle-scale resolution is constructed to simultaneously incorporate the orientation dependence of interparticle interactions and the rotational invariance of the system, a fundamental but challenging issue in modeling the structure and dynamics of a broad range of material systems across variable scales. This generalized phase field crystal-type approach is based upon the complete expansion of particle direct correlation functions and the concept of isotropic tensors. Through applications to the modeling of various two- and three-dimensional crystalline structures, our study demonstrates the capability of bond-angle control in this continuum field theory and its effects on the emergence of ordered phases, and provides a systematic way of performing tunable angle analyses for crystalline microstructures.

Repetitive Transcranial Magnetic Stimulator with Controllable Pulse Parameters

PubMed Central

Peterchev, Angel V; Murphy, David L; Lisanby, Sarah H

2013-01-01

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT) modules to generate near-rectangular electric field pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable pulse parameter TMS (cTMS) device can induce electric field pulses with phase widths of 10–310 μs and positive/negative phase amplitude ratio of 1–56. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation by up to 82% and 57%, and decreases coil heating by up to 33% and 41%, respectively. We demonstrate repetitive TMS trains of 3,000 pulses at frequencies up to 50 Hz with electric field pulse amplitude and width variability less than the measurement resolution (1.7% and 1%, respectively). Offering flexible pulse parameter adjustment and reduced power consumption and coil heating, cTMS enhances existing TMS paradigms, enables novel research applications, and could lead to clinical applications with potentially enhanced potency. PMID:21540487

Research on Parallel Three Phase PWM Converters base on RTDS

NASA Astrophysics Data System (ADS)

Xia, Yan; Zou, Jianxiao; Li, Kai; Liu, Jingbo; Tian, Jun

2018-01-01

Converters parallel operation can increase capacity of the system, but it may lead to potential zero-sequence circulating current, so the control of circulating current was an important goal in the design of parallel inverters. In this paper, the Real Time Digital Simulator (RTDS) is used to model the converters parallel system in real time and study the circulating current restraining. The equivalent model of two parallel converters and zero-sequence circulating current(ZSCC) were established and analyzed, then a strategy using variable zero vector control was proposed to suppress the circulating current. For two parallel modular converters, hardware-in-the-loop(HIL) study based on RTDS and practical experiment were implemented, results prove that the proposed control strategy is feasible and effective.

Inter-decadal change in potential predictability of the East Asian summer monsoon

NASA Astrophysics Data System (ADS)

Li, Jiao; Ding, Ruiqiang; Wu, Zhiwei; Zhong, Quanjia; Li, Baosheng; Li, Jianping

2018-05-01

The significant inter-decadal change in potential predictability of the East Asian summer monsoon (EASM) has been investigated using the signal-to-noise ratio method. The relatively low potential predictability appears from the early 1950s through the late 1970s and during the early 2000s, whereas the potential predictability is relatively high from the early 1980s through the late 1990s. The inter-decadal change in potential predictability of the EASM can be attributed mainly to variations in the external signal of the EASM. The latter is mostly caused by the El Niño-Southern Oscillation (ENSO) inter-decadal variability. As a major external signal of the EASM, the ENSO inter-decadal variability experiences phase transitions from negative to positive phases in the late 1970s, and to negative phases in the late 1990s. Additionally, ENSO is generally strong (weak) during a positive (negative) phase of the ENSO inter-decadal variability. The strong ENSO is expected to have a greater influence on the EASM, and vice versa. As a result, the potential predictability of the EASM tends to be high (low) during a positive (negative) phase of the ENSO inter-decadal variability. Furthermore, a suite of Pacific Pacemaker experiments suggests that the ENSO inter-decadal variability may be a key pacemaker of the inter-decadal change in potential predictability of the EASM.

Energy efficiency technologies in cement and steel industry

NASA Astrophysics Data System (ADS)

Zanoli, Silvia Maria; Cocchioni, Francesco; Pepe, Crescenzo

2018-02-01

In this paper, Advanced Process Control strategies aimed at energy efficiency achievement and improvement in cement and steel industry are proposed. A flexible and smart control structure constituted by several functional modules and blocks has been developed. The designed control strategy is based on Model Predictive Control techniques, formulated on linear models. Two industrial control solutions have been developed, oriented to energy efficiency and process control improvement in cement industry clinker rotary kilns (clinker production phase) and in steel industry billets reheating furnaces. Tailored customization procedures for the design of ad hoc control systems have been executed, based on the specific needs and specifications of the analysed processes. The installation of the developed controllers on cement and steel plants produced significant benefits in terms of process control which resulted in working closer to the imposed operating limits. With respect to the previous control systems, based on local controllers and/or operators manual conduction, more profitable configurations of the crucial process variables have been provided.

A numerical study on the seasonal variability of polychlorinated biphenyls from the atmosphere in the East China Sea.

PubMed

Ono, Jun; Takahashi, Daisuke; Guo, Xinyu; Takahashi, Shin; Takeoka, Hidetaka

2012-10-01

A three-dimensional/high-resolution transport model for persistent organic pollutants (POPs) has been developed for the East China Sea (ECS). The POPs model has four compartments (gaseous, dissolved, phytoplankton-bound, and detritus-bound phases) and includes processes for diffusive air-water exchange, phytoplankton uptake/depuration to POPs, decomposition of dissolved phase, vertical sinking of phytoplankton, detritus production by phytoplankton mortality, and vertical sinking and decomposition of detritus. The POPs model is coupled with an ocean circulation model that can reproduce the seasonal variation in physical variables to represent the advection and diffusion of POPs. We applied the POPs model to the polychlorinated biphenyl congener 153 (PCB 153) from the atmosphere and examined the behavior of PCB 153 in the ocean. The model showed a remarkable seasonal variability of PCB 153. Concentrations in the dissolved and particulate phases are high in winter (January-March) and low in summer (July-September). In coastal regions, where chlorophyll a concentration is high, horizontal and vertical distributions in the dissolved and particulate PCB 153 concentrations are strongly affected by phytoplankton uptake. The sensitivity experiments on the dynamics of PCB 153 suggested that a change of Henry's law constant associated with water temperature is the major factor controlling the seasonal variability of PCB 153. The model-based yearly mass balance of PCB 153 in the ECS indicated that most of the atmospheric input (35.5 kg year(-1)) is removed by the horizontal advection outside the ECS (19.0 kg year(-1)) and accumulates to the sea bottom by vertical sinking (15.7 kg year(-1)). For comparison with PCB 153, we also conducted simulations for PCB 52, 101, and 180. The seasonal variations are similar to that of PCB 153. The mass balance of PCB 52 that has short half-life time and less hydrophobic property shows the different results compared with PCB 101, 153, and 180. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of Position- and Velocity-Dependent Forces on Reaching Movements at Different Speeds

PubMed Central

Summa, Susanna; Casadio, Maura; Sanguineti, Vittorio

2016-01-01

The speed of voluntary movements is determined by the conflicting needs of maximizing accuracy and minimizing mechanical effort. Dynamic perturbations, e.g., force fields, may be used to manipulate movements in order to investigate these mechanisms. Here, we focus on how the presence of position- and velocity-dependent force fields affects the relation between speed and accuracy during hand reaching movements. Participants were instructed to perform reaching movements under visual control in two directions, corresponding to either low or high arm inertia. The subjects were required to maintain four different movement durations (very slow, slow, fast, very fast). The experimental protocol included three phases: (i) familiarization—the robot generated no force; (ii) force field—the robot generated a force; and (iii) after-effect—again, no force. Participants were randomly assigned to four groups, depending on the type of force that was applied during the “force field” phase. The robot was programmed to generate position-dependent forces—with positive (K+) or negative stiffness (K−)—or velocity-dependent forces, with either positive (B+) or negative viscosity (B−). We focused on path curvature, smoothness, and endpoint error; in the latter we distinguished between bias and variability components. Movements in the high-inertia direction are smoother and less curved; smoothness also increases with movement speed. Endpoint bias and variability are greater in, respectively, the high and low inertia directions. A robust dependence on movement speed was only observed in the longitudinal components of both bias and variability. The strongest and more consistent effects of perturbation were observed with negative viscosity (B−), which resulted in increased variability during force field adaptation and in a reduction of the endpoint bias, which was retained in the subsequent after-effect phase. These findings confirm that training with negative viscosity produces lasting effects in movement accuracy at all speeds. PMID:27965559

Case-control study to evaluate risk factors for the development of sepsis (neutropenia and fever) in dogs receiving chemotherapy.

PubMed

Sorenmo, Karin U; Harwood, Lisa P; King, Lesley G; Drobatz, Kenneth J

2010-03-15

OBJECTIVE-To identify risk factors for development of sepsis in dogs treated with chemotherapeutics and to evaluate the impact of sepsis on outcome. DESIGN-Case-control study. ANIMALS-Client-owned dogs with various cancers undergoing standard chemotherapeutic treatment at the University of Pennsylvania veterinary hospital. PROCEDURES-39 dogs with sepsis (cases) were identified through a search of the medical record database. Controls (n = 77) were randomly selected from dogs admitted during the same time period. Variables analyzed included patient demographics, tumor type, stage, remission status, treatment phase, chemotherapeutics used, and outcome. RESULTS-Dogs that weighed less and dogs with lymphoma were significantly more likely to become septic, compared with larger dogs or dogs with solid tumors. Septic dogs were also significantly more likely to have received doxorubicin (odds ratio [OR], 12.5; 95% confidence interval [CI], 2.4 to 66.0) or vincristine (OR, 9.0; 95% CI, 1.6 to 52.0) than controls. Of the 39 cases, 28 (71.8%) were in the induction phase of their protocol, and 19 of 39 (48.7%) became septic after receiving the chemotherapeutic drug for the first time. Median survival time of the cases (253 days) was not significantly different from that of the controls (371 days). CONCLUSIONS AND CLINICAL RELEVANCE-Dogs that weighed less were at increased risk for chemotherapy-induced sepsis. Tumor type and chemotherapeutic drug used were also important risk factors. These results may lead to the implementation of prophylactic measures, especially when doxorubicin or vincristine is used in the induction phase in small dogs with lymphoma.

Treatment Strategies for Paradoxical Hypertension Following Surgical Correction of Coarctation of the Aorta in Children

PubMed Central

Zwijsen, Eline G.

2017-01-01

Background: Paradoxical hypertension after repair of coarctation of the aorta is a well-known phenomenon. The pathogenesis involves the activation of the sympathetic nervous system (first phase) and renin–angiotensin system (second phase). Only a limited number of different treatment strategies have been published in the literature, without any comparative studies. Methods: Our aim was to describe the current international practice variation surrounding pharmacological treatment currently being employed to treat paradoxical hypertension following the repair of coarctation of the aorta in children. We performed an online survey among 197 members of the Pediatric Cardiac Intensive Care Society. We also conducted a systematic review of the literature regarding the treatment of paradoxical hypertension. Results: Eighty-eight people (45%), from 62 different centers, responded and answered the questions regarding blood pressure control. Nitroprusside is the first drug of choice for initial blood pressure control in 66% of respondents, esmolol in 11%, labetalol in 11%, and angiotensin-converting enzyme inhibitors (ACEIs) are used by 3% of respondents. For oral blood pressure control after discharge from the pediatric intensive care unit, 75% of respondents use ACEIs, 18% use labetalol, and 12% use other beta-blockers (propranolol, carvedilol, atenolol, metoprolol). The systematic review identified 14 articles reporting pharmacological treatment of direct postoperative hypertension following coarctation repair. Conclusion: There is wide practice variability, due to the lack of sufficient compelling evidence. The majority (66%) of caregivers use nitroprusside to control blood pressure in the acute postoperative phase. The ACEIs are the drug of choice for chronic blood pressure control. PMID:28520538

Pulse-phase dependence of emission lines in the X-ray pulsar 4U 1626-67

NASA Astrophysics Data System (ADS)

Beri, Aru; Paul, Biswajit; Dewangan, Gulab C.

2015-07-01

We present results from a pulse-phase-resolved spectroscopy of the complex emission lines around 1 keV in the unique accretion-powered X-ray pulsar 4U 1626-67, using the observation made with XMM-Newton in 2003. In this source, the redshifted and blueshifted emission lines and the linewidths measured earlier with Chandra suggest their accretion-disc origin. Another possible signature of lines produced in the accretion disc can be a modulation of the line strength with the pulse phase. We have found that the line fluxes have pulse-phase dependence, making 4U 1626-67 only the second pulsar after Hercules X-1 to show such variability. The O VII line at 0.568 keV from 4U 1626-67 varied by a factor of ˜4, stronger than the continuum variability, which supports the accretion-disc origin. The line flux variability can appear due to variable illumination of the accretion disc by the pulsar or, more likely, a warp-like structure in the accretion disc. We also discuss some further possible diagnostics of the accretion disc in 4U 1626-67 with pulse-phase-resolved emission-line spectroscopy.

Fuzzy logic feedback control for fed-batch enzymatic hydrolysis of lignocellulosic biomass.

PubMed

Tai, Chao; Voltan, Diego S; Keshwani, Deepak R; Meyer, George E; Kuhar, Pankaj S

2016-06-01

A fuzzy logic feedback control system was developed for process monitoring and feeding control in fed-batch enzymatic hydrolysis of a lignocellulosic biomass, dilute acid-pretreated corn stover. Digested glucose from hydrolysis reaction was assigned as input while doser feeding time and speed of pretreated biomass were responses from fuzzy logic control system. Membership functions for these three variables and rule-base were created based on batch hydrolysis data. The system response was first tested in LabVIEW environment then the performance was evaluated through real-time hydrolysis reaction. The feeding operations were determined timely by fuzzy logic control system and efficient responses were shown to plateau phases during hydrolysis. Feeding of proper amount of cellulose and maintaining solids content was well balanced. Fuzzy logic proved to be a robust and effective online feeding control tool for fed-batch enzymatic hydrolysis.

Application of Bounded Linear Stability Analysis Method for Metrics-Driven Adaptive Control

NASA Technical Reports Server (NTRS)

Bakhtiari-Nejad, Maryam; Nguyen, Nhan T.; Krishnakumar, Kalmanje

2009-01-01

This paper presents the application of Bounded Linear Stability Analysis (BLSA) method for metrics-driven adaptive control. The bounded linear stability analysis method is used for analyzing stability of adaptive control models, without linearizing the adaptive laws. Metrics-driven adaptive control introduces a notion that adaptation should be driven by some stability metrics to achieve robustness. By the application of bounded linear stability analysis method the adaptive gain is adjusted during the adaptation in order to meet certain phase margin requirements. Analysis of metrics-driven adaptive control is evaluated for a second order system that represents a pitch attitude control of a generic transport aircraft. The analysis shows that the system with the metrics-conforming variable adaptive gain becomes more robust to unmodeled dynamics or time delay. The effect of analysis time-window for BLSA is also evaluated in order to meet the stability margin criteria.

Effects of feeding blends of grains naturally contaminated with Fusarium mycotoxins on small intestinal morphology of turkeys.

PubMed

Girish, C K; Smith, T K

2008-06-01

An experiment was conducted to investigate the effects of feeding grains naturally contaminated with Fusarium mycotoxins on morphometric indices of duodenum, jejunum, and ileum in turkeys. The possible preventative effect of a polymeric glucomannan mycotoxin adsorbent (GMA) was also determined. Three hundred 1-d-old male turkey poults were fed wheat, corn, and soybean meal-based starter (0 to 3 wk), grower (4 to 6 wk), developer (7 to 9 wk), and finisher (10 to 12 wk) diets formulated with control grains, contaminated grains, and contaminated grains + 0.2% GMA. Morphometric indices were measured at the end of each growth phase and included villus height (VH), crypt depth, villus width, thicknesses of submucosa and muscularis, villus-to-crypt ratio, and apparent villus surface area (AVSA). At the end of the starter phase, feedborne mycotoxins significantly decreased the VH in the duodenum, and supplementation of the contaminated diet with GMA prevented this effect. The feeding of contaminated grains also reduced (P < 0.05) VH and AVSA in jejunum, whereas none of the variables were affected in the ileum. Villus width and AVSA of duodenum, VH, and AVSA of jejunum and submucosa thickness of ileum were significantly reduced when birds were fed contaminated grains at the end of the grower phase, and supplementation with GMA prevented these effects in jejunum and ileum. No effects of diets were seen on morphometric variables at the end of the developer and finisher phases. It was concluded that consumption of grains naturally contaminated with Fusarium mycotoxins results in adverse effects on intestinal morphology during early growth phases of turkeys, and GMA can prevent many of these effects.

Mixed Layer Temperature Budget for the Northward Propagating Summer Monsoon Intraseasonal Oscillation (MISO) in the Central Bay of Bengal

NASA Astrophysics Data System (ADS)

Girishkumar, M. S.; Joseph, J.; Thangaprakash, V. P.; Pottapinjara, V.; McPhaden, M. J.

2017-11-01

Composite analyses of mixed layer temperature (MLT) budget terms from near-surface meteorological and oceanic observations in the central Bay of Bengal are utilized to evaluate the modulation of air-sea interactions and MLT processes in response to the summer monsoon intraseasonal oscillation (MISO). For this purpose, we use moored buoy data at 15°N, 12°N, and 8°N along 90°E together with TropFlux meteorological parameters and the Ocean Surface Current Analyses Real-time (OSCAR) current product. Our analysis shows a strong cooling tendency in MLT with maximum amplitude in the central and northern BoB during the northward propagation of enhanced convective activity associated with the active phase of the MISO; conversely, warming occurs during the suppressed phase of the MISO. The surface mixed layer is generally heated during convectively inactive phases of the MISO primarily due to increased net surface heat flux into the ocean. During convectively active MISO phases, the surface mixed layer is cooled by the combined influence of net surface heat loss to the atmosphere and entrainment cooling at the base of mixed layer. The variability of net surface heat flux is primarily due to modulation of latent heat flux and shortwave radiation. Shortwave is mostly controlled by an enhancement or reduction of cloudiness during the active and inactive MISO phases and latent heat flux is mostly controlled by variations in air-sea humidity difference.

Lack of effect of bezafibrate and fenofibrate on the pharmacokinetics and pharmacodynamics of repaglinide

PubMed Central

Kajosaari, Lauri I; Backman, Janne T; Neuvonen, Mikko; Laitila, Jouko; Neuvonen, Pertti J

2004-01-01

Aims Gemfibrozil markedly increases the plasma concentrations and blood glucose-lowering effects of repaglinide, but the effects of other fibrates on repaglinide pharmacokinetics are not known. Our aim was to investigate the effects of bezafibrate and fenofibrate on the pharmacokinetics and pharmacodynamics of repaglinide. Methods In a randomized, three-phase cross-over study, 12 healthy subjects received 400 mg bezafibrate, 200 mg fenofibrate or placebo once daily for 5 days. On day 5, a single 0.25 mg dose of repaglinide was ingested 1 h after the last pretreatment dose. The concentrations of plasma repaglinide, bezafibrate and fenofibrate and blood glucose were measured up to 7 h postdose. Results During the bezafibrate and fenofibrate phases, the total area under the concentration-time curve [AUC(0,∞)] of repaglinide was 99% (95% confidence interval of the ratio to the control phase 73, 143%) and 99% (85, 127%) of the corresponding value during the placebo (control) phase, respectively. Bezafibrate and fenofibrate had no significant effect on the peak concentration (Cmax) of repaglinide. The mean half-life of repaglinide was 1.3 h in all phases. The blood glucose-lowering effect of repaglinide was not affected by bezafibrate or fenofibrate. The AUC(0,8 h) values for bezafibrate and fenofibrate varied 3.0-fold and 4.4-fold between individual subjects, respectively. Neither bezafibrate nor fenofibrate affected the pharmacokinetic variables of repaglinide. Conclusions Bezafibrate and fenofibrate do not affect the pharmacokinetics or pharmacodynamics of repaglinide. PMID:15373931

Characterization of a Genomic Signature of Pregnancy in the Breast

PubMed Central

Belitskaya-Lévy, Ilana; Zeleniuch-Jacquotte, Anne; Russo, Jose; Russo, Irma H.; Bordás, Pal; Åhman, Janet; Afanasyeva, Yelena; Johansson, Robert; Lenner, Per; Li, Xiaochun; de Cicco, Ricardo López; Peri, Suraj; Ross, Eric; Russo, Patricia A.; Santucci-Pereira, Julia; Sheriff, Fathima S.; Slifker, Michael; Hallmans, Göran; Toniolo, Paolo; Arslan, Alan A.

2012-01-01

The objective of the current study was to comprehensively compare the genomic profiles in the breast of parous and nulliparous postmenopausal women to identify genes that permanently change their expression following pregnancy. The study was designed as a two-phase approach. In the discovery phase, we compared breast genomic profiles of 37 parous with 18 nulliparous postmenopausal women. In the validation phase, confirmation of the genomic patterns observed in the discovery phase was sought in an independent set of 30 parous and 22 nulliparous postmenopausal women. RNA was hybridized to Affymetrix HG_U133 Plus 2.0 oligonucleotide arrays containing probes to 54,675 transcripts; scanned and the images analyzed using Affymetrix GCOS software. Surrogate variable analysis, logistic regression and significance analysis for microarrays were used to identify statistically significant differences in expression of genes. The False Discovery Rate (FDR) approach was used to control for multiple comparisons. We found that 208 genes (305 probe sets) were differentially expressed between parous and nulliparous women in both discovery and validation phases of the study at a FDR of 10% and with at least a 1.25-fold change. These genes are involved in regulation of transcription, centrosome organization, RNA splicing, cell cycle control, adhesion and differentiation. The results provide persuasive evidence that full-term pregnancy induces long-term genomic changes in the breast. The genomic signature of pregnancy could be used as an intermediate marker to assess potential chemopreventive interventions with hormones mimicking the effects of pregnancy for prevention of breast cancer. PMID:21622728

A stochastic model of input effectiveness during irregular gamma rhythms.

PubMed

Dumont, Grégory; Northoff, Georg; Longtin, André

2016-02-01

Gamma-band synchronization has been linked to attention and communication between brain regions, yet the underlying dynamical mechanisms are still unclear. How does the timing and amplitude of inputs to cells that generate an endogenously noisy gamma rhythm affect the network activity and rhythm? How does such "communication through coherence" (CTC) survive in the face of rhythm and input variability? We present a stochastic modelling approach to this question that yields a very fast computation of the effectiveness of inputs to cells involved in gamma rhythms. Our work is partly motivated by recent optogenetic experiments (Cardin et al. Nature, 459(7247), 663-667 2009) that tested the gamma phase-dependence of network responses by first stabilizing the rhythm with periodic light pulses to the interneurons (I). Our computationally efficient model E-I network of stochastic two-state neurons exhibits finite-size fluctuations. Using the Hilbert transform and Kuramoto index, we study how the stochastic phase of its gamma rhythm is entrained by external pulses. We then compute how this rhythmic inhibition controls the effectiveness of external input onto pyramidal (E) cells, and how variability shapes the window of firing opportunity. For transferring the time variations of an external input to the E cells, we find a tradeoff between the phase selectivity and depth of rate modulation. We also show that the CTC is sensitive to the jitter in the arrival times of spikes to the E cells, and to the degree of I-cell entrainment. We further find that CTC can occur even if the underlying deterministic system does not oscillate; quasicycle-type rhythms induced by the finite-size noise retain the basic CTC properties. Finally a resonance analysis confirms the relative importance of the I cell pacing for rhythm generation. Analysis of whole network behaviour, including computations of synchrony, phase and shifts in excitatory-inhibitory balance, can be further sped up by orders of magnitude using two coupled stochastic differential equations, one for each population. Our work thus yields a fast tool to numerically and analytically investigate CTC in a noisy context. It shows that CTC can be quite vulnerable to rhythm and input variability, which both decrease phase preference.

Phenology of seed and leaves rain in response to periodic climatic variability in a seasonal wet tropical forest

NASA Astrophysics Data System (ADS)

Matteo, D.; Wright, S. J.; Davies, S. J.; Muller-Landau, H. C.; Wolfe, B.; Detto, M.

2016-12-01

Phenology, by controlling the rhythms of plants, plays a fundamental role in regulating access to resources, ecosystem processes, competition among species, interactions with consumers and feedbacks to the climate. In high biodiverse tropical forests, where phenology of flowering and leafing are complex, an adequate representation of phenology must take into account a given set of climatic, edaphic and biotic factors. Climatic factors are particularly important because plants may use them as cues for timing different phenological phases and be influenced by their intensity. Climatic variability can be periodic, if events occur with regular frequency, or aperiodic. One prominent periodic large-scale pattern that causes unusual weather is ENSO event. In general, Central America tends to be dry and warm during a mature phase of an ENSO event, which usually peaks between October and January with a frequency of 2-3 events per decade. Because in many tropical areas the effect of ENSO is highly prominent, it is plausible that plants have adapted their growth and reproduction mechanisms to synchronize ENSO phases, in a similar way that plants do during the seasonal cycle. We used a long dataset (30+ years) of fruits and leaves rains of tropical trees and lianas to determine ecosystem response and species specific response of these phenological events to local climate variability corresponding to the modes of ENSO. Specifically, we tested the hypothesis that phenological responses to ENSO are similar to response to seasonal cycles, i.e., higher litterfall before a warm-dry phase and higher fruiting after such phase, with strong correlation between seeds and leaves. At sub-community level, we evaluated whether evergreen and deciduous, biotic and abiotic dispersers and free and climbing life forms, have the same response to ENSO in terms of leaves and seeds rain. At species level we tested the hypothesis that species with low photosynthetic capacity leaves are more responsive to ENSO in relation to variation in solar radiation. High Amax is usually associated with light-demanding, fast growing, gap species. These species must disperse seeds to ephemeral gaps to germinate successfully. Consequently they strategize to have more even seed fall across years

Head Stability and Head-Trunk Coordination in Horseback Riders: The Contribution of Visual Information According to Expertise

PubMed Central

Olivier, Agnès; Faugloire, Elise; Lejeune, Laure; Biau, Sophie; Isableu, Brice

2017-01-01

Maintaining equilibrium while riding a horse is a challenging task that involves complex sensorimotor processes. We evaluated the relative contribution of visual information (static or dynamic) to horseback riders' postural stability (measured from the variability of segment position in space) and the coordination modes they adopted to regulate balance according to their level of expertise. Riders' perceptual typologies and their possible relation to postural stability were also assessed. Our main assumption was that the contribution of visual information to postural control would be reduced among expert riders in favor of vestibular and somesthetic reliance. Twelve Professional riders and 13 Club riders rode an equestrian simulator at a gallop under four visual conditions: (1) with the projection of a simulated scene reproducing what a rider sees in the real context of a ride in an outdoor arena, (2) under stroboscopic illumination, preventing access to dynamic visual cues, (3) in normal lighting but without the projected scene (i.e., without the visual consequences of displacement) and (4) with no visual cues. The variability of the position of the head, upper trunk and lower trunk was measured along the anteroposterior (AP), mediolateral (ML), and vertical (V) axes. We computed discrete relative phase to assess the coordination between pairs of segments in the anteroposterior axis. Visual field dependence-independence was evaluated using the Rod and Frame Test (RFT). The results showed that the Professional riders exhibited greater overall postural stability than the Club riders, revealed mainly in the AP axis. In particular, head variability was lower in the Professional riders than in the Club riders in visually altered conditions, suggesting a greater ability to use vestibular and somesthetic information according to task constraints with expertise. In accordance with this result, RFT perceptual scores revealed that the Professional riders were less dependent on the visual field than were the Club riders. Finally, the Professional riders exhibited specific coordination modes that, unlike the Club riders, departed from pure in-phase and anti-phase patterns and depended on visual conditions. The present findings provide evidence of major differences in the sensorimotor processes contributing to postural control with expertise in horseback riding. PMID:28194100

Dynamic balance in persons with multiple sclerosis who have a falls history is altered compared to non-fallers and to healthy controls.

PubMed

Peebles, Alexander T; Bruetsch, Adam P; Lynch, Sharon G; Huisinga, Jessie M

2017-10-03

Around 60% of persons with multiple sclerosis (MS) experience falls, however the dynamic balance differences between those who fall and those who don't are not well understood. The purpose of this study is to identify distinct biomechanical features of dynamic balance during gait that are different between fallers with MS, non-fallers with MS, and healthy controls. 27 recurrent fallers with MS, 28 persons with MS with no falls history, and 27 healthy controls walked on a treadmill at their preferred speed for 3min. The variability of trunk accelerations and the average and variability of minimum toe clearance, spatiotemporal parameters, and margin of stability were compared between groups. Fallers with MS exhibited a slower cautious gait compared to non-fallers and healthy controls, but had decreased anterior-posterior margin of stability and minimum toe clearance. Fallers walked with less locally stable and predictable trunk accelerations, and increased variability of step length, stride time, and both anterior-posterior and mediolateral margin of stability compared to non-fallers and healthy controls. The present work provides evidence that within a group of persons with MS, there are gait differences that are influenced by falls history. These differences indicate that in persons with MS who fall, the center of mass is poorly controlled through base of support placement and the foot is closer to the ground during swing phase relative to the non-fallers. These identified biomechanical differences could be used to evaluate dynamic balance in persons with MS and to help improve fall prevention strategies. Copyright © 2017. Published by Elsevier Ltd.

Wind-energy recovery by a static Scherbius induction generator

NASA Astrophysics Data System (ADS)

Smith, G. A.; Nigim, K. A.

1981-11-01

The paper describes a technique for controlling a doubly fed induction generator driven by a windmill, or other form of variable-speed prime mover, to provide power generation into the national grid system. The secondary circuit of the generator is supplied at a variable frequency from a current source inverter which for test purposes is rated to allow energy recovery, from a simulated windmill, from maximum speed to standstill. To overcome the stability problems normally associated with doubly fed machines a novel signal generator, which is locked in phase with the rotor EMF, controls the secondary power to provide operation over a wide range of subsynchronous and supersynchronous speeds. Consideration of power flow enables the VA rating of the secondary power source to be determined as a function of the gear ratio and online operating range of the system. A simple current source model is used to predict performance which is compared with experimental results. The results indicate a viable system, and suggestions for further work are proposed.

Stationarity of the Tropical Pacific Teleconnection to North America in CMIP5 PMIP3 Model Simulations

NASA Technical Reports Server (NTRS)

Coats, Sloan; Smerdon, Jason E.; Cook, Benjamin I.; Seager, Richard

2013-01-01

The temporal stationarity of the teleconnection between the tropical Pacific Ocean and North America (NA) is analyzed in atmosphere-only, and coupled last-millennium, historical, and control runs from the Coupled Model Intercomparison Project Phase 5 data archive. The teleconnection, defined as the correlation between December-January-February (DJF) tropical Pacific sea surface temperatures (SSTs) and DJF 200 mb geopotential height, is found to be nonstationary on multidecadal timescales. There are significant changes in the spatial features of the teleconnection over NA in continuous 56-year segments of the last millennium and control simulations. Analysis of atmosphere-only simulations forced with observed SSTs indicates that atmospheric noise cannot account for the temporal variability of the teleconnection, which instead is likely explained by the strength of, and multidecadal changes in, tropical Pacific Ocean variability. These results have implications for teleconnection-based analyses of model fidelity in simulating precipitation, as well as any reconstruction and forecasting efforts that assume stationarity of the observed teleconnection.

Non-equilibrium thermodynamical description of rhythmic motion patterns of active systems: a canonical-dissipative approach.

PubMed

Dotov, D G; Kim, S; Frank, T D

2015-02-01

We derive explicit expressions for the non-equilibrium thermodynamical variables of a canonical-dissipative limit cycle oscillator describing rhythmic motion patterns of active systems. These variables are statistical entropy, non-equilibrium internal energy, and non-equilibrium free energy. In particular, the expression for the non-equilibrium free energy is derived as a function of a suitable control parameter. The control parameter determines the Hopf bifurcation point of the deterministic active system and describes the effective pumping of the oscillator. In analogy to the equilibrium free energy of the Landau theory, it is shown that the non-equilibrium free energy decays as a function of the control parameter. In doing so, a similarity between certain equilibrium and non-equilibrium phase transitions is pointed out. Data from an experiment on human rhythmic movements is presented. Estimates for pumping intensity as well as the thermodynamical variables are reported. It is shown that in the experiment the non-equilibrium free energy decayed when pumping intensity was increased, which is consistent with the theory. Moreover, pumping intensities close to zero could be observed at relatively slow intended rhythmic movements. In view of the Hopf bifurcation underlying the limit cycle oscillator model, this observation suggests that the intended limit cycle movements were actually more similar to trajectories of a randomly perturbed stable focus. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

SiC MOSFET Based Single Phase Active Boost Rectifier with Power Factor Correction for Wireless Power Transfer Applications

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

Onar, Omer C; Tang, Lixin; Chinthavali, Madhu Sudhan

2014-01-01

Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges the utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance due to variable parameters such as battery state-of-charge, coupling factor, and coil misalignment. This paper presents the implementation of an active front-end rectifier on the grid side formore » power factor control and voltage boost capability for load power regulation. The proposed SiC MOSFET based single phase active front end rectifier with PFC resulted in >97% efficiency at 137mm air-gap and >95% efficiency at 160mm air-gap.« less

[Study of serum levels of interlukin-2 and its receptor, interlukin-6, sICAM-1, sVCAM-1 in patients with recurrent genital herpes].

PubMed

Zhang, Min; Zhang, Yizhi

2003-01-01

To study cellular immunity status and serum levels of adhesion molecules of patients with recurrent genital herpes. Serum levels of interlukin-2 and its soluble receptor, interlukin-6, sICAM-1, sVCAM-1 were measured by ELISA in 34 patients with recurrent genital herpes. The serum levels of IL-2 and IL-6 were significantly lower in patients than in healthy controls (P < 0.01). The levels of sIL-2R, sICAM-1 and sVCAM-1 were significantly higher in patients than in controls (P < 0.05). No significant differences were seen in all variables of patients in relapse phase and remission phase (P > 0.05). There are cellular immunity deficiency and high serum levels of adhesion molecules in patients with recurrent genital herpes, and these changes may be related to therecurrence of genital herpes and the development of inflammatory reaction.

A biphasic epigenetic switch controls immunoevasion, virulence and niche adaptation in non-typeable Haemophilus influenzae.

PubMed

Atack, John M; Srikhanta, Yogitha N; Fox, Kate L; Jurcisek, Joseph A; Brockman, Kenneth L; Clark, Tyson A; Boitano, Matthew; Power, Peter M; Jen, Freda E-C; McEwan, Alastair G; Grimmond, Sean M; Smith, Arnold L; Barenkamp, Stephen J; Korlach, Jonas; Bakaletz, Lauren O; Jennings, Michael P

2015-07-28

Non-typeable Haemophilus influenzae contains an N(6)-adenine DNA-methyltransferase (ModA) that is subject to phase-variable expression (random ON/OFF switching). Five modA alleles, modA2, modA4, modA5, modA9 and modA10, account for over two-thirds of clinical otitis media isolates surveyed. Here, we use single molecule, real-time (SMRT) methylome analysis to identify the DNA-recognition motifs for all five of these modA alleles. Phase variation of these alleles regulates multiple proteins including vaccine candidates, and key virulence phenotypes such as antibiotic resistance (modA2, modA5, modA10), biofilm formation (modA2) and immunoevasion (modA4). Analyses of a modA2 strain in the chinchilla model of otitis media show a clear selection for ON switching of modA2 in the middle ear. Our results indicate that a biphasic epigenetic switch can control bacterial virulence, immunoevasion and niche adaptation in an animal model system.

Individualized treatment with transcranial direct current stimulation in patients with chronic non-fluent aphasia due to stroke

PubMed Central

Shah-Basak, Priyanka P.; Norise, Catherine; Garcia, Gabriella; Torres, Jose; Faseyitan, Olufunsho; Hamilton, Roy H.

2015-01-01

While evidence suggests that transcranial direct current stimulation (tDCS) may facilitate language recovery in chronic post-stroke aphasia, individual variability in patient response to different patterns of stimulation remains largely unexplored. We sought to characterize this variability among chronic aphasic individuals, and to explore whether repeated stimulation with an individualized optimal montage could lead to persistent reduction of aphasia severity. In a two-phase study, we first stimulated patients with four active montages (left hemispheric anode or cathode; right hemispheric anode or cathode) and one sham montage (Phase 1). We examined changes in picture naming ability to address (1) variability in response to different montages among our patients, and (2) whether individual patients responded optimally to at least one montage. During Phase 2, subjects who responded in Phase 1 were randomized to receive either real-tDCS or to receive sham stimulation (10 days); patients who were randomized to receive sham stimulation first were then crossed over to receive real-tDCS (10 days). In both phases, 2 mA tDCS was administered for 20 min per real-tDCS sessions and patients performed a picture naming task during stimulation. Patients' language ability was re-tested after 2-weeks and 2-months following real and sham tDCS in Phase 2. In Phase 1, despite considerable individual variability, the greatest average improvement was observed after left-cathodal stimulation. Seven out of 12 subjects responded optimally to at least one montage as demonstrated by transient improvement in picture-naming. In Phase 2, aphasia severity improved at 2-weeks and 2-months following real-tDCS but not sham. Despite individual variability with respect to optimal tDCS approach, certain montages result in consistent transient improvement in persons with chronic post-stroke aphasia. This preliminary study supports the notion that individualized tDCS treatment may enhance aphasia recovery in a persistent manner. PMID:25954178

Changes in heart rate variability are associated with expression of short-term and long-term contextual and cued fear memories.

PubMed

Liu, Jun; Wei, Wei; Kuang, Hui; Zhao, Fang; Tsien, Joe Z

2013-01-01

Heart physiology is a highly useful indicator for measuring not only physical states, but also emotional changes in animals. Yet changes of heart rate variability during fear conditioning have not been systematically studied in mice. Here, we investigated changes in heart rate and heart rate variability in both short-term and long-term contextual and cued fear conditioning. We found that while fear conditioning could increase heart rate, the most significant change was the reduction in heart rate variability which could be further divided into two distinct stages: a highly rhythmic phase (stage-I) and a more variable phase (stage-II). We showed that the time duration of the stage-I rhythmic phase were sensitive enough to reflect the transition from short-term to long-term fear memories. Moreover, it could also detect fear extinction effect during the repeated tone recall. These results suggest that heart rate variability is a valuable physiological indicator for sensitively measuring the consolidation and expression of fear memories in mice.

The variable and chaotic nature of professional golf performance.

PubMed

Stöckl, Michael; Lamb, Peter F

2018-05-01

In golf, unlike most other sports, individual performance is not the result of direct interactions between players. Instead decision-making and performance is influenced by numerous constraining factors affecting each shot. This study looked at the performance of PGA TOUR golfers in 2011 in terms of stability and variability on a shot-by-shot basis. Stability and variability were assessed using Recurrence Quantification Analysis (RQA) and standard deviation, respectively. About 10% of all shots comprised short stable phases of performance (3.7 ± 1.1 shots per stable phase). Stable phases tended to consist of shots of typical performance, rather than poor or exceptional shots; this finding was consistent for all shot categories. Overall, stability measures were not correlated with tournament performance. Variability across all shots was not related to tournament performance; however, variability in tee shots and short approach shots was higher than for other shot categories. Furthermore, tee shot variability was related to tournament standing: decreased variability was associated with better tournament ranking. The findings in this study showed that PGA TOUR golf performance is chaotic. Further research on amateur golf performance is required to determine whether the structure of amateur golf performance is universal.

Dynamics and Synchronization of Nonlinear Oscillators with Time Delays: A Study with Fiber Lasers

DTIC Science & Technology

2007-07-19

or coupling lines PC Polarization Controller PD Photodetector VA Variable Attenuator WDM Wavelength Division Multiplexer x Chapter 1 Introduction 1.1...lasers and detectors. Injection locking of lasers is a common practice that can be used to lock the frequency and phase of a laser to an injected signal...finding a basis vector that maximizes the mean squared projection of the data. Succeeding basis vectors are found that max- imize the projection with the

Nonlinear Signal Processing and Team Differential Games.

DTIC Science & Technology

1986-03-01

w can be viewed as a control variable belonging to a mythical mini- mizing third party, such that (33) is a Nash strategy. It can be shown that the...Morgenstern [2] the discrete game analysis embodied most of the prin- ciples of the game theory yet recognized as important. But it is not until the...more common variety. Nor can it be treated as a second phase of a bargaining game with coalitions already formed, such as studied by Von Netman and

Effective inertial coefficient for the dinuclear regime of the exotic decay of nuclei

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

Duarte, S.B.; Goncalves, M.G.

Geometric and incompressibility constraint relations are used explicitly in reducing the number of collective variables of the dinuclear phase of the fissioning system to calculate the barrier penetrability factor. Consistently, we define an effective inertial coefficient for the relative motion of the fissioning system. With this inertial coefficient, half-lives of the exotic and alpha decays are successfully reproduced for all available experimental data, using only one well-controlled nuclear parameter, the nuclear radius constant. {copyright} {ital 1996 The American Physical Society.}

Quasielastic neutron scattering with in situ humidity control: Water dynamics in uranyl fluoride

DOE PAGES

Miskowiec, A.; Kirkegaard, M. C.; Herwig, K. W.; ...

2016-03-04

The authors confirm that water vapor pressure is the driving thermodynamic force for the conversion of the anhydrous structure to [(UO 2F 2)(H 2O)] 7 ∙ (H 2O) 4, and they demonstrate the feasibility of extending this approach to aqueous forms of UO 2F 2+ xH 2O. This method has general applicability to systems in which water content itself is a driving variable for structural or dynamical phase transitions.

Anterior Cruciate Ligament Injuries in the National Hockey League: Epidemiology and Performance Impact.

PubMed

Longstaffe, Robert; Leiter, Jeff; MacDonald, Peter

2018-03-27

To determine the incidence of anterior cruciate ligament (ACL) injuries in the National Hockey League (NHL) and to examine the effects of this injury on return-to-play status and performance. Case series; level of evidence, 4. This was a 2-phase study. Phase I used the NHL electronic injury surveillance system and Athlete Health Management System to collect data on ACL injuries and man games lost over 10 seasons (2006/2007-2015/2016). Data collected in phase I were received in deidentified form. Phase II examined the performance impact of an ACL injury. Players were identified through publically available sources, and performance-related statistics were analyzed. Data collected in phase II were not linked to data collected in phase I. A paired t test was used to determine any difference in the matching variables between controls and cases in the preinjury time period. A General linear model (mixed) was used to determine the performance impact. Phase I: 67 ACL injuries occurred over 10 seasons. The incidence for all players was 0.42/1000 player game hours (forward, 0.61; defenseman, 0.32, goalie, 0.08) and by game exposure was 0.2/1000 player game exposures (forward, 0.33; defenseman, 0.11; goalie, 0.07). Forwards had a greater incidence rate of ACL tears with both game hours and game exposures when compared with defensemen and goalies (P < 0.001, <0.001; P = 0.008, <0.001, respectively). Phase II: 70 ACL tears (60 players) were identified. Compared with controls, players who suffered an ACL tear demonstrated a decrease in goals/season (P < 0.04), goals/game (P < 0.015), points/season (0.007), and points/game (0.001). Number of games and seasons played after an ACL injury did not differ compared with controls (P = 0.068, 0.122, respectively). Anterior cruciate ligament injuries occur infrequently, as it relates to other hockey injuries. Despite a high return to play, the performance after an ACL injury demonstrated a decrease in points and goals per game and per season.

Evolving changes in fetal heart rate variability and brain injury after hypoxia-ischaemia in preterm fetal sheep.

PubMed

Yamaguchi, Kyohei; Lear, Christopher A; Beacom, Michael J; Ikeda, Tomoaki; Gunn, Alistair J; Bennet, Laura

2018-01-08

Fetal heart rate variability is a critical index of fetal wellbeing. Suppression of heart rate variability may provide prognostic information on the risk of hypoxic-ischaemic brain injury after birth. In the present study, we report the evolution of fetal heart rate variability after both mild and severe hypoxia-ischaemia. Both mild and severe hypoxia-ischaemia were associated with an initial, brief suppression of multiple measures of heart rate variability. This was followed by normal or increased levels of heart rate variability during the latent phase of injury. Severe hypoxia-ischaemia was subsequently associated with the prolonged suppression of measures of heart rate variability during the secondary phase of injury, which is the period of time when brain injury is no longer treatable. These findings suggest that a biphasic pattern of heart rate variability may be an early marker of brain injury when treatment or intervention is probably most effective. Hypoxia-ischaemia (HI) is a major contributor to preterm brain injury, although there are currently no reliable biomarkers for identifying infants who are at risk. We tested the hypothesis that fetal heart rate (FHR) and FHR variability (FHRV) would identify evolving brain injury after HI. Fetal sheep at 0.7 of gestation were subjected to either 15 (n = 10) or 25 min (n = 17) of complete umbilical cord occlusion or sham occlusion (n = 12). FHR and four measures of FHRV [short-term variation, long-term variation, standard deviation of normal to normal R-R intervals (SDNN), root mean square of successive differences) were assessed until 72 h after HI. All measures of FHRV were suppressed for the first 3-4 h in the 15 min group and 1-2 h in the 25 min group. Measures of FHRV recovered to control levels by 4 h in the 15 min group, whereas the 25 min group showed tachycardia and an increase in short-term variation and SDNN from 4 to 6 h after occlusion. The measures of FHRV then progressively declined in the 25 min group and became profoundly suppressed from 18 to 48 h. A partial recovery of FHRV measures towards control levels was observed in the 25 min group from 49 to 72 h. These findings illustrate the complex regulation of FHRV after both mild and severe HI and suggest that the longitudinal analysis of FHR and FHRV after HI may be able to help determine the timing and severity of preterm HI. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

Dynamic knee stability and ballistic knee movement after ACL reconstruction: an application on instep soccer kick.

PubMed

Cordeiro, Nuno; Cortes, Nelson; Fernandes, Orlando; Diniz, Ana; Pezarat-Correia, Pedro

2015-04-01

The instep soccer kick is a pre-programmed ballistic movement with a typical agonist-antagonist coordination pattern. The coordination pattern of the kick can provide insight into deficient neuromuscular control. The purpose of this study was to investigate knee kinematics and hamstrings/quadriceps coordination pattern during the knee ballistic extension phase of the instep kick in soccer players after anterior cruciate ligament reconstruction (ACL reconstruction). Seventeen players from the Portuguese Soccer League participated in this study. Eight ACL-reconstructed athletes (experimental group) and 9 healthy individuals (control group) performed three instep kicks. Knee kinematics (flexion and extension angles at football contact and maximum velocity instants) were calculated during the kicks. Rectus femoris (RF), vastus lateralis, vastus medialis, biceps femoralis, and semitendinosus muscle activations were quantified during the knee extension phase. The ACL-reconstructed group had significantly lower knee extension angle (-1.2 ± 1.6, p < 0.021) and increased variability (1.1 ± 1.2, p < 0.012) when compared with the control group. Within the EMG variables, the RF had a significantly greater activity in the ACL-reconstructed group than in the control group (79.9 ± 27.7 % MVC vs. 49.2 ± 20.8 % MVC, respectively, p < 0.034). No other statistically significant differences were found. The findings of this study demonstrate that changes in ACL-reconstructed individuals were observed on knee extension angle and RF muscle activation while performing an instep kick. These findings are in accordance with the knee stability recovery process after ACL reconstruction. No differences were observed in the ballistic control movement pattern between normal and ACL-reconstructed subjects. Performing open kinetic chain exercises using ballistic movements can be beneficial when recovering from ACL reconstruction. The exercises should focus on achieving multi-joint coordination and full knee extension (range of motion). III.

Diffuse-interface model for rapid phase transformations in nonequilibrium systems.

PubMed

Galenko, Peter; Jou, David

2005-04-01

A thermodynamic approach to rapid phase transformations within a diffuse interface in a binary system is developed. Assuming an extended set of independent thermodynamic variables formed by the union of the classic set of slow variables and the space of fast variables, we introduce finiteness of the heat and solute diffusive propagation at the finite speed of the interface advancing. To describe transformations within the diffuse interface, we use the phase-field model which allows us to follow steep but smooth changes of phase within the width of the diffuse interface. Governing equations of the phase-field model are derived for the hyperbolic model, a model with memory, and a model of nonlinear evolution of transformation within the diffuse interface. The consistency of the model is proved by the verification of the validity of the condition of positive entropy production and by outcomes of the fluctuation-dissipation theorem. A comparison with existing sharp-interface and diffuse-interface versions of the model is given.

Selectivity in reversed-phase separations: general influence of solvent type and mobile phase pH.

PubMed

Neue, Uwe D; Méndez, Alberto

2007-05-01

The influence of the mobile phase on retention is studied in this paper for a group of over 70 compounds with a broad range of multiple functional groups. We varied the pH of the mobile phase (pH 3, 7, and 10) and the organic modifier (methanol, acetonitrile (ACN), and tetrahydrofuran (THF)), using 15 different stationary phases. In this paper, we describe the overall retention and selectivity changes observed with these variables. We focus on the primary effects of solvent choice and pH. For example, transfer rules for solvent composition resulting in equivalent retention depend on the packing as well as on the type of analyte. Based on the retention patterns, one can calculate selectivity difference values for different variables. The selectivity difference is a measure of the importance of the different variables involved in method development. Selectivity changes specific to the type of analyte are described. The largest selectivity differences are obtained with pH changes.

Repeating coupled earthquakes at Shishaldin Volcano, Alaska

USGS Publications Warehouse

Caplan-Auerbach, J.; Petersen, T.

2005-01-01

Since it last erupted in 1999, Shishaldin Volcano, Aleutian Islands, Alaska, has produced hundreds to thousands of long-period (1-2 Hz; LP) earthquakes every day with no other sign of volcanic unrest. In 2002, the earthquakes also exhibited a short-period (4-7 Hz; SP) signal occurring between 3 and 15 s before the LP phase. Although the SP phase contains higher frequencies than the LP phase, its spectral content is still well below that expected of brittle failure events. The SP phase was never observed without the LP phase, although LP events continued to occur in the absence of the precursory signal. The two-phased events are termed "coupled events", reflecting a triggered relationship between two discrete event types. Both phases are highly repetitive in time series, suggestive of stable, non-destructive sources. Waveform cross-correlation and spectral coherence are used to extract waveforms from the continuous record and determine precise P-wave arrivals for the SP phase. Although depths are poorly constrained, the SP phase is believed to lie at shallow (<4 km) depths just west of Shishaldin's summit. The variable timing between the SP and LP arrivals indicates that the trigger mechanism between the phases itself moves at variable speeds. A model is proposed in which the SP phase results from fluid moving within the conduit, possibly around an obstruction and the LP phase results from the coalescence of a shallow gas bubble. The variable timing is attributed to changes in gas content within the conduit. The destruction of the conduit obstacle on November 21, 2002 resulted in the abrupt disappearance of the SP phase.

Comprehensive mutagenesis of the fimS promoter regulatory switch reveals novel regulation of type 1 pili in uropathogenic Escherichia coli

PubMed Central

Zhang, Huibin; Susanto, Teodorus T.; Wan, Yue

2016-01-01

Type 1 pili (T1P) are major virulence factors for uropathogenic Escherichia coli (UPEC), which cause both acute and recurrent urinary tract infections. T1P expression therefore is of direct relevance for disease. T1P are phase variable (both piliated and nonpiliated bacteria exist in a clonal population) and are controlled by an invertible DNA switch (fimS), which contains the promoter for the fim operon encoding T1P. Inversion of fimS is stochastic but may be biased by environmental conditions and other signals that ultimately converge at fimS itself. Previous studies of fimS sequences important for T1P phase variation have focused on laboratory-adapted E. coli strains and have been limited in the number of mutations or by alteration of the fimS genomic context. We surmounted these limitations by using saturating genomic mutagenesis of fimS coupled with accurate sequencing to detect both mutations and phase status simultaneously. In addition to the sequences known to be important for biasing fimS inversion, our method also identifies a previously unknown pair of 5′ UTR inverted repeats that act by altering the relative fimA levels to control phase variation. Thus we have uncovered an additional layer of T1P regulation potentially impacting virulence and the coordinate expression of multiple pilus systems. PMID:27035967

Comprehensive mutagenesis of the fimS promoter regulatory switch reveals novel regulation of type 1 pili in uropathogenic Escherichia coli.

PubMed

Zhang, Huibin; Susanto, Teodorus T; Wan, Yue; Chen, Swaine L

2016-04-12

Type 1 pili (T1P) are major virulence factors for uropathogenic Escherichia coli (UPEC), which cause both acute and recurrent urinary tract infections. T1P expression therefore is of direct relevance for disease. T1P are phase variable (both piliated and nonpiliated bacteria exist in a clonal population) and are controlled by an invertible DNA switch (fimS), which contains the promoter for the fim operon encoding T1P. Inversion of fimS is stochastic but may be biased by environmental conditions and other signals that ultimately converge at fimS itself. Previous studies of fimS sequences important for T1P phase variation have focused on laboratory-adapted E coli strains and have been limited in the number of mutations or by alteration of the fimS genomic context. We surmounted these limitations by using saturating genomic mutagenesis of fimS coupled with accurate sequencing to detect both mutations and phase status simultaneously. In addition to the sequences known to be important for biasing fimS inversion, our method also identifies a previously unknown pair of 5' UTR inverted repeats that act by altering the relative fimA levels to control phase variation. Thus we have uncovered an additional layer of T1P regulation potentially impacting virulence and the coordinate expression of multiple pilus systems.

Control of complex components with Smart Flexible Phased Arrays.

PubMed

Casula, O; Poidevin, C; Cattiaux, G; Dumas, Ph

2006-12-22

The inspection is mainly performed in contact with ultrasonic wedge transducers; However, the shape cannot fit the changing geometries of components (butt weld, nozzle, elbow). The variable thickness of the coupling layer, between the wedge and the local surface, leads to beam distortions and losses of sensitivity. Previous studies have shown that these two phenomena contribute to reduce the inspection performances leading to shadow area, split beam.... Flexible phased arrays have been developed to fit the complex profile and improve such controls. The radiating surface is composed with independent piezoelectric elements mechanically assembled and a profilometer, embedded in the transducer, measures the local distortion. The computed shape is used by an algorithm to compute in real-time the adapted delay laws compensating the distortions of 2D or 3D profiles. Those delay laws are transferred to the real-time UT acquisition system, which applies them to the piezoelectric elements. This self-adaptive process preserves, during the scanning, the features of the focused beam (orientation and focal depth) in the specimen. To validate the concept of the Smart Flexible Phased Array Transducer, prototypes have been integrated to detect flaws machined in mock-ups with realistic irregular 2D and 3D shapes. Inspections have been carried out on samples showing the enhancement performances of the "Smart Flexible Phased Array" and validating the mechanical and acoustical behaviors of these probes.

A Priori Subgrid Analysis of Temporal Mixing Layers with Evaporating Droplets

NASA Technical Reports Server (NTRS)

Okongo, Nora; Bellan, Josette

1999-01-01

Subgrid analysis of a transitional temporal mixing layer with evaporating droplets has been performed using three sets of results from a Direct Numerical Simulation (DNS) database, with Reynolds numbers (based on initial vorticity thickness) as large as 600 and with droplet mass loadings as large as 0.5. In the DNS, the gas phase is computed using a Eulerian formulation, with Lagrangian droplet tracking. The Large Eddy Simulation (LES) equations corresponding to the DNS are first derived, and key assumptions in deriving them are first confirmed by computing the terms using the DNS database. Since LES of this flow requires the computation of unfiltered gas-phase variables at droplet locations from filtered gas-phase variables at the grid points, it is proposed to model these by assuming the gas-phase variables to be the sum of the filtered variables and a correction based on the filtered standard deviation; this correction is then computed from the Subgrid Scale (SGS) standard deviation. This model predicts the unfiltered variables at droplet locations considerably better than simply interpolating the filtered variables. Three methods are investigated for modeling the SGS standard deviation: the Smagorinsky approach, the Gradient model and the Scale-Similarity formulation. When the proportionality constant inherent in the SGS models is properly calculated, the Gradient and Scale-Similarity methods give results in excellent agreement with the DNS.

H2/H∞ control for grid-feeding converter considering system uncertainty

NASA Astrophysics Data System (ADS)

Li, Zhongwen; Zang, Chuanzhi; Zeng, Peng; Yu, Haibin; Li, Shuhui; Fu, Xingang

2017-05-01

Three-phase grid-feeding converters are key components to integrate distributed generation and renewable power sources to the power utility. Conventionally, proportional integral and proportional resonant-based control strategies are applied to control the output power or current of a GFC. But, those control strategies have poor transient performance and are not robust against uncertainties and volatilities in the system. This paper proposes a H2/H∞-based control strategy, which can mitigate the above restrictions. The uncertainty and disturbance are included to formulate the GFC system state-space model, making it more accurate to reflect the practical system conditions. The paper uses a convex optimisation method to design the H2/H∞-based optimal controller. Instead of using a guess-and-check method, the paper uses particle swarm optimisation to search a H2/H∞ optimal controller. Several case studies implemented by both simulation and experiment can verify the superiority of the proposed control strategy than the traditional PI control methods especially under dynamic and variable system conditions.

High key rate continuous-variable quantum key distribution with a real local oscillator.

PubMed

Wang, Tao; Huang, Peng; Zhou, Yingming; Liu, Weiqi; Ma, Hongxin; Wang, Shiyu; Zeng, Guihua

2018-02-05

Continuous-variable quantum key distribution (CVQKD) with a real local oscillator (LO) has been extensively studied recently due to its security and simplicity. In this paper, we propose a novel implementation of a high-key-rate CVQKD with a real LO. Particularly, with the help of the simultaneously generated reference pulse, the phase drift of the signal is tracked in real time and then compensated. By utilizing the time and polarization multiplexing techniques to isolate the reference pulse and controlling the intensity of it, not only the contamination from it is suppressed, but also a high accuracy of the phase compensation can be guaranteed. Besides, we employ homodyne detection on the signal to ensure the high quantum efficiency and heterodyne detection on the reference pulse to acquire the complete phase information of it. In order to suppress the excess noise, a theoretical noise model for our scheme is established. According to this model, the impact of the modulation variance and the intensity of the reference pulse are both analysed theoretically and then optimized according to the experimental data. By measuring the excess noise in the 25km optical fiber transmission system, a 3.14Mbps key rate in the asymptotic regime proves to be achievable. This work verifies the feasibility of the high-key-rate CVQKD with a real LO within the metropolitan area.