Investigation of a Light Gas Helicon Plasma Source for the VASIMR Space Propulsion System

NASA Technical Reports Server (NTRS)

Squire, J. P.; Chang-Diaz, F. R.; Jacobson, V. T.; Glover, T. W.; Baity, F. W.; Carter, M. D.; Goulding, R. H.; Bengtson, R. D.; Bering, E. A., III

2003-01-01

An efficient plasma source producing a high-density (approx.10(exp 19/cu m) light gas (e.g. H, D, or He) flowing plasma with a high degree of ionization is a critical component of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept. We are developing an antenna to apply ICRF power near the fundamental ion cyclotron resonance to further accelerate the plasma ions to velocities appropriate for space propulsion applications. The high degree of ionization and a low vacuum background pressure are important to eliminate the problem of radial losses due to charge exchange. We have performed parametric (e.g. gas flow, power (0.5 - 3 kW), magnetic field , frequency (25 and 50 MHz)) studies of a helicon operating with gas (H2 D2, He, N2 and Ar) injected at one end with a high magnetic mirror downstream of the antenna. We have explored operation with a cusp and a mirror field upstream. Plasma flows into a low background vacuum (<10(exp -4) torr) at velocities higher than the ion sound speed. High densities (approx. 10(exp 19/cu m) have been achieved at the location where ICRF will be applied, just downstream of the magnetic mirror.

Plasma Heating Simulation in the VASIMR System

NASA Technical Reports Server (NTRS)

Ilin, Andrew V.; ChangDiaz, Franklin R.; Squire, Jared P.; Carter, Mark D.

2005-01-01

The paper describes the recent development in the simulation of the ion-cyclotron acceleration of the plasma in the VASIMR experiment. The modeling is done using an improved EMIR code for RF field calculation together with particle trajectory code for plasma transport calculat ion. The simulation results correlate with experimental data on the p lasma loading and predict higher ICRH performance for a higher density plasma target. These simulations assist in optimizing the ICRF anten na so as to achieve higher VASIMR efficiency.

Computer Simulation of the VASIMR Engine

NASA Technical Reports Server (NTRS)

Garrison, David

2005-01-01

The goal of this project is to develop a magneto-hydrodynamic (MHD) computer code for simulation of the VASIMR engine. This code is designed be easy to modify and use. We achieve this using the Cactus framework, a system originally developed for research in numerical relativity. Since its release, Cactus has become an extremely powerful and flexible open source framework. The development of the code will be done in stages, starting with a basic fluid dynamic simulation and working towards a more complex MHD code. Once developed, this code can be used by students and researchers in order to further test and improve the VASIMR engine.

A Plasma Rocket Demonstration on the International Space Station

NASA Astrophysics Data System (ADS)

Petro, A.

2002-01-01

in the development of a magneto-plasma rocket for several years. This type of rocket could be used in the future to propel interplanetary spacecraft. One feature of this concept is the ability to vary its specific impulse so that it can be operated in a mode that maximizes propellant efficiency or a mode that maximizes thrust. For this reason the system is called the Variable Specific Impulse Magneto-plasma Rocket or VASIMR. This ability to vary specific impulse and thrust will allow for optimum low thrust interplanetary trajectories and results in shorter trip times than is possible with fixed specific impulse systems while preserving adequate payload margins. demonstrations are envisioned. A ground-based experiment of a low-power VASIMR prototype rocket is currently underway at the Advanced Space Propulsion Laboratory. The next step is a proposal to build and fly a 25-kilowatt VASIMR rocket as an external payload on the International Space Station. This experiment will provide an opportunity to demonstrate the performance of the rocket in space and measure the induced environment. The experiment will also utilize the space station for its intended purpose as a laboratory with vacuum conditions that cannot be matched by any laboratory on Earth. propulsion on the space station. An electric propulsion system like VASIMR, if provided with sufficient electrical power, could provide continuous drag force compensation for the space station. Drag compensation would eliminate the need for reboosting the station, an operation that will consume about 60 metric tons of propellant in a ten-year period. In contrast, an electric propulsion system would require very little propellant. In fact, a system like VASIMR can use waste hydrogen from the station's life support system as its propellant. This waste hydrogen is otherwise dumped overboard. Continuous drag compensation would also improve the microgravity conditions on the station. So electric propulsion can reduce propellant delivery requirements and thereby increase available payload capacity and at the same time improve the conditions for scientific research. and the space environment. This is a beneficial effect that prevents a charge buildup on the station. The station already operates two dedicated non-propulsive plasma contactor devices for this purpose. A VASIMR rocket would function as an additional plasma contactor. would be delivered to orbit in the Space Shuttle payload bay. It would be mounted on a standard payload attachment structure. After removal from the payload bay by the shuttle robotic arm, it would be handed to the space station robotic arm which would place it at an external payload attach site on the station truss. A mating device for power and data connections exists at the payload site. The experiment would receive one to three kilowatts of power from the station. About 600 watts would be used for cryogenic cooling and control devices. Additional power would be stored in a set of batteries. The VASIMR experiment would be operated for short periods when the batteries can provide power to the amplifiers that feed radio-frequency power to the thruster assembly. The thruster assembly is composed of an inner tube in which the neutral propellant is injected and ionized and a larger tube, which supports the radio frequency antennas, which ionize the gas and heat the plasma. Electromagnet coils that provide the magnetic field to constrain the flow of the plasma and form the magnetic exit nozzle surround these tubes. to this supply are planned for the experiment. The experiment will carry two dedicated propellant tanks which each have the capacity to store all the propellant needed for an experimental program lasting several months. With two propellant tanks, the opportunity exists to perform experiments with more than one type of propellant. Hydrogen is the primary choice for propellant but deuterium and helium are also of interest and might also be included. All the propellant is stored and used in gaseous form at ambient temperature. rocket. There is a superconducting electromagnet that will need to be maintained at cryogenic temperatures in order to operate properly. The magnet is in close proximity to the plasma so a combination of compact insulation and passive and active heat transport techniques will be employed. activity requirements. However, provisions will be included to capitalize on the presence of humans in case repairs or servicing is required. The batteries, propellant tanks, and electronic components will be designed for on-orbit removal and replacement, if necessary. could be located on the station to provide useful thrust for drag compensation. In order to provide power for continuous thrusting, it may be necessary to augment the power generation system for the station. Another attractive possibility is to develop an electric propulsion testbed for the space station. This testbed could be used for testing and certifying a variety of propulsion systems at various stages of maturity while providing thrust for the space station. This station facility would be a valuable asset for commercial and government space transportation programs. more powerful and capable propulsion systems that will be demonstrated on free-flying spacecraft in near-Earth space and eventually on missions to the planets.

Kinetic models for the VASIMR thruster helicon plasma source

NASA Astrophysics Data System (ADS)

Batishchev, Oleg; Molvig, Kim

2001-10-01

Helicon gas discharge [1] is widely used by industry because of its remarkable efficiency [2]. High energy and fuel efficiencies make it very attractive for space electrical propulsion applications. For example, helicon plasma source is used in the high specific impulse VASIMR [3] plasma thruster, including experimental prototypes VX-3 and upgraded VX-10 [4] configurations, which operate with hydrogen (deuterium) and helium plasmas. We have developed a set of models for the VASIMR helicon discharge. Firstly, we use zero-dimensional energy and mass balance equations to characterize partially ionized gas condition/composition. Next, we couple it to one-dimensional hybrid model [6] for gas flow in the quartz tube of the helicon. We compare hybrid model results to a purely kinetic simulation of propellant flow in gas feed + helicon source subsystem. Some of the experimental data [3-4] are explained. Lastly, we discuss full-scale kinetic modeling of coupled gas and plasmas [5-6] in the helicon discharge. [1] M.A.Lieberman, A.J.Lihtenberg, 'Principles of ..', Wiley, 1994; [2] F.F.Chen, Plas. Phys. Contr. Fus. 33, 339, 1991; [3] F.Chang-Diaz et al, Bull. APS 45 (7) 129, 2000; [4] J.Squire et al., Bull. APS 45 (7) 130, 2000; [5] O.Batishchev et al, J. Plasma Phys. 61, part II, 347, 1999; [6] O.Batishchev, K.Molvig, AIAA technical paper 2000-3754, -14p, 2001.

Next Generation H- Ion Sources for the SNS

NASA Astrophysics Data System (ADS)

Welton, R. F.; Stockli, M. P.; Murray, S. N.; Crisp, D.; Carmichael, J.; Goulding, R. H.; Han, B.; Tarvainen, O.; Pennisi, T.; Santana, M.

2009-03-01

The U.S. Spallation Neutron Source (SNS) is the leading accelerator-based, pulsed neutron-scattering facility, currently in the process of ramping up neutron production. In order to insure meeting operational requirements as well as providing for future facility beam power upgrades, a multifaceted H- ion source development program is ongoing. This work discusses several aspects of this program, specifically the design and first beam measurements of an RF-driven, external antenna H- ion source based on an A1N ceramic plasma chamber, elemental and chromate Cs-systems, and plasma ignition gun. Unanalyzed beam currents of up to ˜100 mA (60 Hz, 1 ms) have been observed and sustained currents >60 mA (60 Hz, 1 ms) have been demonstrated on the test stand. Accelerated beam currents of ˜40 mA have also been demonstrated into the SNS front end. Data are also presented describing the first H- beam extraction experiments from a helicon plasma generator based on the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) engine design.

Dual-mode, high energy utilization system concept for mars missions

NASA Astrophysics Data System (ADS)

El-Genk, Mohamed S.

2000-01-01

This paper describes a dual-mode, high energy utilization system concept based on the Pellet Bed Reactor (PeBR) to support future manned missions to Mars. The system uses proven Closed Brayton Cycle (CBC) engines to partially convert the reactor thermal power to electricity. The electric power generated is kept the same during the propulsion and the power modes, but the reactor thermal power in the former could be several times higher, while maintaining the reactor temperatures almost constant. During the propulsion mode, the electric power of the system, minus ~1-5 kWe for house keeping, is used to operate a Variable Specific Impulse Magnetoplasma Rocket (VASIMR). In addition, the reactor thermal power, plus more than 85% of the head load of the CBC engine radiators, are used to heat hydrogen. The hot hydrogen is mixed with the high temperature plasma in a VASIMR to provide both high thrust and Isp>35,000 N.s/kg, reducing the travel time to Mars to about 3 months. The electric power also supports surface exploration of Mars. The fuel temperature and the inlet temperatures of the He-Xe working fluid to the nuclear reactor core and the CBC turbine are maintained almost constant during both the propulsion and power modes to minimize thermal stresses. Also, the exit temperature of the He-Xe from the reactor core is kept at least 200 K below the maximum fuel design temperature. The present system has no single point failure and could be tested fully assembled in a ground facility using electric heaters in place of the nuclear reactor. Operation and design parameters of a 40-kWe prototype are presented and discussed to illustrate the operation and design principles of the proposed system. .

Magnetic Field Effects on Plasma Plumes

NASA Technical Reports Server (NTRS)

Ebersohn, F.; Shebalin, J.; Girimaji, S.; Staack, D.

2012-01-01

Here, we will discuss our numerical studies of plasma jets and loops, of basic interest for plasma propulsion and plasma astrophysics. Space plasma propulsion systems require strong guiding magnetic fields known as magnetic nozzles to control plasma flow and produce thrust. Propulsion methods currently being developed that require magnetic nozzles include the VAriable Specific Impulse Magnetoplasma Rocket (VASIMR) [1] and magnetoplasmadynamic thrusters. Magnetic nozzles are functionally similar to de Laval nozzles, but are inherently more complex due to electromagnetic field interactions. The two crucial physical phenomenon are thrust production and plasma detachment. Thrust production encompasses the energy conversion within the nozzle and momentum transfer to a spacecraft. Plasma detachment through magnetic reconnection addresses the problem of the fluid separating efficiently from the magnetic field lines to produce maximum thrust. Plasma jets similar to those of VASIMR will be studied with particular interest in dual jet configurations, which begin as a plasma loops between two nozzles. This research strives to fulfill a need for computational study of these systems and should culminate with a greater understanding of the crucial physics of magnetic nozzles with dual jet plasma thrusters, as well as astrophysics problems such as magnetic reconnection and dynamics of coronal loops.[2] To study this problem a novel, hybrid kinetic theory and single fluid magnetohydrodynamic (MHD) solver known as the Magneto-Gas Kinetic Method is used.[3] The solver is comprised of a "hydrodynamic" portion based on the Gas Kinetic Method and a "magnetic" portion that accounts for the electromagnetic behaviour of the fluid through source terms based on the resistive MHD equations. This method is being further developed to include additional physics such as the Hall effect. Here, we will discuss the current level of code development, as well as numerical simulation results

A Flight Demonstration of Plasma Rocket Propulsion

NASA Technical Reports Server (NTRS)

Petro, Andrew; Chang-Diaz, Franklin; Schwenterly, WIlliam; Hitt, Michael; Lepore, Joseph

2000-01-01

The Advanced Space Propulsion Laboratory at the NASA Johnson Space Center has been engaged in the development of a variable specific impulse magnetoplasma rocket (V ASIMR) for several years. This type of rocket could be used in the future to propel interplanetary spacecraft and has the potential to open the entire solar system to human exploration. One feature of this propulsion technology is the ability to vary its specific impulse so that it can be operated in a mode that maximizes propellant efficiency or a mode that maximizes thrust. Variation of specific impulse and thrust enhances the ability to optimize interplanetary trajectories and results in shorter trip times and lower propellant requirements than with a fixed specific impulse. In its ultimate application for interplanetary travel, the VASIMR would be a multi-megawatt device. A much lower power system is being designed for demonstration in the 2004 timeframe. This first space demonstration would employ a lO-kilowatt thruster aboard a solar powered spacecraft in Earth orbit. The 1O-kilowatt V ASIMR demonstration unit would operate for a period of several months with hydrogen or deuterium propellant with a specific impulse of 10,000 seconds.

Preliminary design of an asteroid hopping mission

NASA Astrophysics Data System (ADS)

Scheppa, Michael D.

In 2010, NASA announced that its new vision is to support private space launch operations. It is anticipated that this new direction will create the need for new and innovative ideas that push the current boundaries of space exploration and contain the promise of substantial gain, both in research and capital. The purpose of the study is to plan and estimate the feasibility of a mission to visit a number of near Earth asteroids (NEAs). The mission would take place before the end of the 21st century, and would only use commercially available technology. Throughout the mission design process, while holding astronaut safety paramount, it was the goal to maximize the return while keeping the cost to a minimum. A mission of the nature would appeal to the private space industry because it could be easily adapted and set into motion. The mission design was divided into three main parts; mission timeline, vehicle design and power sources, with emphasis on nuclear and solar electric power, were investigated. The timeline and associated trajectories were initially selected using a numerical estimation and then optimized using Satellite Tool Kit (STK) 9.s's Design Explorer Optimizer [1]. Next, the spacecraft was design using commercially available parts that would support the mission requirements. The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) was and instrumental piece in maximizing the number of NEAs visited. Once the spacecraft was designed, acceptable power supply options were investigated. The VASIMR VX-200 requires 200 kilowatts of power to maintain thrust. This creates the need for a substantial power supply that consists of either a nuclear reactor of massive solar arrays. STK 9.1's Design Explorer Optimizer was able to create a mission time line that allowed for the exploration of seven NEAs in under two years, while keeping the total mission DeltaV under 71 kilometers per second. Based on these initial findings, it is determined that a mission of this nature is feasible and would could greatly benefit the private space industry.

MW-Class Electric Propulsion System Designs for Mars Cargo Transport

NASA Technical Reports Server (NTRS)

Gilland, James H.; LaPointe, Michael R.; Oleson, Steven; Mercer, Carolyn; Pencil, Eric; Maosn, Lee

2011-01-01

Multi-kilowatt electric propulsion systems are well developed and have been used on commercial and military satellites in Earth orbit for several years. Ion and Hall thrusters have also propelled robotic spacecraft to encounters with asteroids, the Moon, and minor planetary bodies within the solar system. High power electric propulsion systems are currently being considered to support piloted missions to near earth asteroids, as cargo transport for sustained lunar or Mars exploration, and for very high-power piloted missions to Mars and the outer planets. Using NASA Mars Design Architecture 5.0 as a reference, a preliminary parametric analysis was performed to determine the suitability of a nuclear powered, MW-class electric propulsion system for Mars cargo transport. For this initial analysis, high power 100-kW Hall thrusters and 250-kW VASIMR engines were separately evaluated to determine optimum vehicle architecture and estimated performance. The DRA 5.0 cargo mission closed for both propulsion options, delivering a 100 t payload to Mars orbit and reducing the number of heavy lift launch vehicles from five in the baseline DRA 5.0 architecture to two using electric propulsion. Under an imposed single engine-out mission success criteria, the VASIMR system took longer to reach Mars than did the Hall system, arising from the need to operate the VASIMR thrusters in pairs during the spiral out from low Earth orbit.

High Power Ion Cyclotron Heating in the VASIMR

NASA Astrophysics Data System (ADS)

Longmier, B. W.; Brukardt, M. S.; Bering, E. A.; Chang Diaz, F.; Squire, J.

2009-12-01

The Variable Specific Impulse Magnetoplasma Rocket (VASIMR®) is an electric propulsion system under development at Ad Astra Rocket Company that utilizes several processes of ion acceleration and heating that occur in the Birkeland currents of an auroral arc system. Among these processes are parallel electric field acceleration, lower hybrid resonance heating, and ion cyclotron resonance heating. The VASIMR® is capable of laboratory simulation of electromagnetic ion cyclotron wave heating during a single pass of ions through the resonance region. The plasma is generated by a helicon discharge of 35 kW then passes through a 176 kW RF booster stage that couples left hand polarized slow mode waves from the high field side of the resonance. VX-200 auroral simulation results from the past year are discussed. Ambipolar acceleration has been shown to produce 35eV argon ions in the helicon exhaust. The effects on the ion exhaust with an addition of 150-200 kW of ion cyclotron heating are presented. The changes to the VASIMR® experiment at Ad Astra Rocket Company's new facility in Webster, Texas will also be discussed, including the possibility of collaborative experiments.

The VASIMR[registered trademark] VF-200-1 ISS Experiment as a Laboratory for Astrophysics

NASA Technical Reports Server (NTRS)

Glover Tim W.; Squire, Jared P.; Longmier, Benjamin; Cassady, Leonard; Ilin, Andrew; Carter, Mark; Olsen, Chris S.; McCaskill, Greg; Diaz, Franklin Chang; Girimaji, Sharath;

Turbulence-induced anomalous electron diffusion in the plume of the VASIMR VX-200

NASA Astrophysics Data System (ADS)

Olsen, Christopher; Ballenger, Maxwell; Squire, Jared; Longmier, Benjamin; Carter, Mark; Glover, Tim

2012-10-01

The separation of electrons from magnetic nozzles is critical to the function of the VASIMR engine and is of general importance to the field of electric propulsion. Separation of electrons by means of anomalous cross field diffusion is considered. Plume measurements using spectral analysis of custom high frequency probes characterizes the nature of oscillating electric fields in the expanding magnetic nozzle. The oscillating electric field results in frequency dependent density variations that can lead to anomalously high transport in the absence of collisions mimicking collisional transport. The spatial structure of the fluctuating fields is consistent with turbulence caused by separation of energetic (> 100 eV) non-magnetized ions and low energy magnetized electrons via the modified two-stream instability (MTSI) and generalized lower hybrid drift instability (GLHDI). Electric fields as high as 300 V/m are observed at frequencies up to an order of magnitude above the lower hybrid frequency. The electric field fluctuations dissipate with increasing axial distance consistent with changes in ion flux streamlines as plasma detachment occurs.

VASIMR VX-200 thruster throttling optimization from 30 to 200 kW

NASA Astrophysics Data System (ADS)

Squire, Jared; Olsen, Chris; Chang-Diaz, Franklin; Longmier, Benjamin; Ballenger, Maxwell; Carter, Mark; Glover, Tim; McCaskill, Greg

2012-10-01

The VASIMR^ VX-200 experimental plasma thruster incorporates a 40 kW helicon plasma source with a 180 kW Ion Cyclotron Heating (ICH) acceleration stage integrated in a superconducting magnet. Argon propellant mass flow is injected up to 140 mg/s. Rapid plasma start up (< 100 ms) and high pumping speed (> 10^5 liters/s) in a 150 m^3 vacuum chamber achieve performance measurements with the charge exchange mean-free-path greater than 1 m in the background neutral gas (pressure < 10-5 Torr). The thruster efficiency at 200 kW total power is 72 ± 9%, the ratio of effective jet power to input RF power, with an Isp = 4900 ± 300 seconds (flow velocity of 49 km/s), and an ion flux of 1.7 ± 0.1 x 10^21/s. The thrust increases steadily with power to 5.8 ± 0.4 N until the power is maximized and there is no indication of saturation. The plasma density near the device exit exceeds 10^18 m-3 with a power density over 5 MW/m^2. An extensive study of thruster performance, efficiency and thrust-to-power ratio, as a function of Ar propellant flow rate and ICH-to-helicon RF power ratio has been carried out over a total power range of 30 to 200 kW. Optimized throttling set points are determined. The experimental configuration and results of this study are presented.

Helical plasma thruster

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

Beklemishev, A. D., E-mail: bekl@bk.ru

2015-10-15

A new scheme of plasma thruster is proposed. It is based on axial acceleration of rotating magnetized plasmas in magnetic field with helical corrugation. The idea is that the propellant ionization zone can be placed into the local magnetic well, so that initially the ions are trapped. The E × B rotation is provided by an applied radial electric field that makes the setup similar to a magnetron discharge. Then, from the rotating plasma viewpoint, the magnetic wells of the helically corrugated field look like axially moving mirror traps. Specific shaping of the corrugation can allow continuous acceleration of trapped plasma ionsmore » along the magnetic field by diamagnetic forces. The accelerated propellant is expelled through the expanding field of magnetic nozzle. By features of the acceleration principle, the helical plasma thruster may operate at high energy densities but requires a rather high axial magnetic field, which places it in the same class as the VASIMR{sup ®} rocket engine.« less

An Examination of "The Martian" Trajectory

NASA Technical Reports Server (NTRS)

Burke, Laura

2015-01-01

This analysis was performed to support a request to examine the trajectory of the Hermes vehicle in the novel "The Martian" by Andy Weir. Weir developed his own tool to perform the analysis necessary to provide proper trajectory information for the novel. The Hermes vehicle is the interplanetary spacecraft that shuttles the crew to and from Mars. It is notionally a Nuclear powered vehicle utilizing VASIMR engines for propulsion. The intent of this analysis was the determine whether the trajectory as it was outlined in the novel is consistent with the rules of orbital mechanics.

High Power Light Gas Helicon Plasma Source for VASIMR

NASA Technical Reports Server (NTRS)

Squire, Jared P.; Chang-Diaz, Franklin R.; Glover, Timothy W.; Jacobson, Verlin T.; Baity, F. Wally; Carter, Mark D.; Goulding, Richard H.

2004-01-01

In the Advanced Space Propulsion Laboratory (ASPL) helicon experiment (VX-10) we have measured a plasma flux to input gas rate ratio near 100% for both helium and deuterium at power levels up to 10 kW. Recent results at Oak Ridge National Laboratory (ORNL) show enhanced efficiency operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter and operates up to 10 kW of input power. The data here uses a Boswell double-saddle antenna design with a magnetic cusp just upstream of the antenna. Similar to ORNL, for deuterium at near 10 kW, we find an enhanced performance of operation at magnetic fields above the lower hybrid matching condition.

Heat flow diagnostics for helicon plasmas.

PubMed

Berisford, Daniel F; Bengtson, Roger D; Raja, Laxminarayan L; Cassady, Leonard D; Chancery, William J

2008-10-01

We present experimental studies of power balance in an argon helicon discharge. An infrared camera measures the heating of the dielectric tube containing a helicon discharge based on measurement of temperature profiles of the tube surface before and after a rf pulse. Using this diagnostic, we have measured surface heating trends at a variety of operating conditions on two helicon systems: the 10 kW VASIMR VX-50 experiment and the University of Texas at Austin 1 kW helicon experiment. Power losses downstream from the antenna are measured using thermocouples and probes. The heating of the dielectric tube increases with decreasing magnetic fields, higher gas flow rates, and higher molecular mass of the gas. These preliminary results suggest that cross-field particle diffusion contributes a significant proportion of the energy flux to the wall.

Heat flow diagnostics for helicon plasmas

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

Berisford, Daniel F.; Bengtson, Roger D.; Raja, Laxminarayan L.

2008-10-15

We present experimental studies of power balance in an argon helicon discharge. An infrared camera measures the heating of the dielectric tube containing a helicon discharge based on measurement of temperature profiles of the tube surface before and after a rf pulse. Using this diagnostic, we have measured surface heating trends at a variety of operating conditions on two helicon systems: the 10 kW VASIMR VX-50 experiment and the University of Texas at Austin 1 kW helicon experiment. Power losses downstream from the antenna are measured using thermocouples and probes. The heating of the dielectric tube increases with decreasing magneticmore » fields, higher gas flow rates, and higher molecular mass of the gas. These preliminary results suggest that cross-field particle diffusion contributes a significant proportion of the energy flux to the wall.« less

Overview of the electric propulsion plasma diagnostics suite for the VASIMR VX-200 testbed

NASA Astrophysics Data System (ADS)

Olsen, Christopher; Longmier, Benjamin; Ballenger, Maxwell; Squire, Jared; Glover, Tim; Carter, Mark; Bering, Edgar; Giambusso, Matthew

2012-10-01

Descriptions of the various plasma diagnostics and data analysis methods are given for instruments used in high power (> 100 kW) electric propulsion testing. These include planar Langmuir probes, an articulating retarding potential analyzer, a double Langmuir probe, a multi-axis magnetometer, a high frequency electric field probe, microwave interferometer, and momentum flux targets. These diagnostics have been used to measure the efficiencies of the thruster, plasma source, ion cyclotron resonance booster, and magnetic nozzle as well as used to explore physical phenomena in the plume such as ion/electron detachment, plasma turbulence, and magnetic field line stretching. Typical plume parameters range up to 10^13 cm-3 electron density, 1 kG applied magnetic fields, ion energies in excess of 150 eV, and cold electrons (2 -- 5 eV) with a spatial measurement range over 2 m.

Momentum and Heat Flux Measurements in the Exhaust of VASIMR Using Helium Propellant

NASA Technical Reports Server (NTRS)

Chavers, D. Gregory

2002-01-01

Electromagnetic thrusters typically use electric and magnetic fields to accelerate and exhaust plasma through interactions with the charged particles in the plasma. The energy required to create the plasma, i.e. ionization energy, is potential energy between the electron and ion. This potential energy is typically lost since it is not recovered as the plasma is exhausted and is known as frozen flow loss. If the frozen flow energy is a small fraction of the total plasma energy, this frozen flow loss may be negligible. However, if the frozen flow energy is a major fraction of the total plasma energy, this loss can severely reduce the energy efficiency of the thruster. Recovery and utilization of this frozen flow energy can improve the energy efficiency of a thruster during low specific impulse operating regimes when the ionization energy is a large fraction of the total plasma energy. This paper quantifies the recovery of the frozen flow energy, i.e. recombination energy, via the process of surface recombination for helium. To accomplish this task the momentum flux and heat flux of the plasma flow were measured and compared to calculated values from electrostatic probe data. This information was used to deduce the contribution of recombination energy to the total heat flux on a flat plate as well as to characterize the plasma conditions. Helium propellant was investigated initially due to its high ionization potential and hence available recombination energy.

Experimental determination of plasma detachment from the diverging magnetic nozzle of the VASIMR VX-200 Electric Thruster

NASA Astrophysics Data System (ADS)

Olsen, Christopher; Squire, Jared; Longmier, Benjamin; Ballenger, Maxwell; Cassady, Leonard; Carter, Mark; Ilin, Andrew; Cloutier, Paul; Bering, Edgar; Giambusso, Matthew; Ad Astra Rocket Company Team; Rice University Collaboration; University of Houston Collaboration

2011-10-01

Theories of magnetized plasma detachment in an expanding magnetic field have been lacking detailed experimental evidence. Recent experiments using a 200 kW class electric rocket (VX-200), run at 100 kW using argon and a peak magnetic field of 2 T, produced ion energies greater than 100 eV with a flux of 2x1022 ions/s in a 150 m3 vacuum facility. Ion-neutral charge exchange effects were reduced and the resultant data show evidence of plasma detachment in a diverging magnetic field on a scale length of 2 m. The detachment is confirmed using multiple plasma diagnostics and magnetic nozzle topologies. Spatial maps of the data are compared to simulations from a particle detachment model, ParTraj, as well as MHD detachment theory. ParTraj, when compared to experiment, is shown to be more consistent in describing the data. Unless the MHD models are modified to incorporation two-fluid effects, single fluid MHD theory is inconsistent with the observations.

NASA Technology Investments in Electric Propulsion: New Directions in the New Millennium

NASA Technical Reports Server (NTRS)

Sankovic, John M.

2002-01-01

The last decade was a period of unprecedented acceptance of NASA developed electric propulsion by the user community. The benefits of high performance electric propulsion systems are now widely recognized, and new technologies have been accepted across the commonly. NASA clearly recognizes the need for new, high performance, electric propulsion technologies for future solar system missions and is sponsoring aggressive efforts in this area. These efforts are mainly conducted under the Office of Aerospace Technology. Plans over the next six years include the development of next generation ion thrusters for end of decade missions. Additional efforts are planned for the development of very high power thrusters, including magnetoplasmadynamic, pulsed inductive, and VASIMR, and clusters of Hall thrusters. In addition to the in-house technology efforts, NASA continues to work closely with both supplier and user communities to maximize the acceptance of new technology in a timely and cost-effective manner. This paper provides an overview of NASA's activities in the area of electric propulsion with an emphasis on future program directions.

Measurement of erosion in helicon plasma thrusters using the VASIMR® VX-CR device

NASA Astrophysics Data System (ADS)

Del Valle Gamboa, Juan Ignacio; Castro-Nieto, Jose; Squire, Jared; Carter, Mark; Chang-Diaz, Franklin

2015-09-01

The helicon plasma source is one of the principal stages of the high-power VASIMR® electric propulsion system. The VASIMR® VX-CR experiment focuses solely on this stage, exploring the erosion and long-term operation effects of the VASIMR helicon source. We report on the design and operational parameters of the VX-CR experiment, and the development of modeling tools and characterization techniques allowing the study of erosion phenomena in helicon plasma sources in general, and stand-alone helicon plasma thrusters (HPTs) in particular. A thorough understanding of the erosion phenomena within HPTs will enable better predictions of their behavior as well as more accurate estimations of their expected lifetime. We present a simplified model of the plasma-wall interactions within HPTs based on current models of the plasma density distributions in helicon discharges. Results from this modeling tool are used to predict the erosion within the plasma-facing components of the VX-CR device. Experimental techniques to measure actual erosion, including the use of coordinate-measuring machines and microscopy, will be discussed.

Solid-State Thermionic Nuclear Power for Megawatt Propulsion, Planetary Surface and Commercial Power Project

NASA Technical Reports Server (NTRS)

George, Jeffrey

2014-01-01

Thermionic (TI) power conversion is a promising technology first investigated for power conversion in the 1960's, and of renewed interest due to modern advances in nanotechnology, MEMS, materials and manufacturing. Benefits include high conversion efficiency (20%), static operation with no moving parts and potential for high reliability, greatly reduced plant complexity, and the potential for reduced development costs. Thermionic emission, credited to Edison in 1880, forms the basis of vacuum tubes and much of 20th century electronics. Heat can be converted into electricity when electrons emitted from a hot surface are collected across a small gap. For example, two "small" (6 kWe) Thermionic Space Reactors were flown by the USSR in 1987-88 for ocean radar reconnaissance. Higher powered Nuclear-Thermionic power systems driving Electric Propulsion (Q-thruster, VASIMR, etc.) may offer the breakthrough necessary for human Mars missions of < 1 yr round trip. Power generation on Earth could benefit from simpler, moe economical nuclear plants, and "topping" of more fuel and emission efficient fossil-fuel plants.

Advanced Power and Propulsion: Insuring Human Survival and Productivity in Deep Space Missions

NASA Technical Reports Server (NTRS)

Chang-Diaz, Franklin R.

2001-01-01

Dr. Chang-Diaz gave an intriguing presentation of his research in advanced rocket propulsion and its relevance for planning and executing crewed deep space explorations. Though not necessarily exclusively Martian, his thrust looks critically at future Mars missions. Initially Dr. Chang-Diaz showed the time constraints of Mars missions due to orbital mechanics and our present chemically powered rocket technology. Since essentially all the energy required to place current generation spacecraft into a Martian trajectory must be expended in the early minutes of a flight, most of such a mission is spent in free-fall drift, captive to the gravitational forces among Earth, the Sun, and Mars. The simple physics of such chemically powered missions requires nearly a year in transit for each direction of a Mars mission. And the optimal orientations of Earth and Mars for rendezvous require further time on or around Mars to await return. These extensions of mission duration place any crew under a three-fold jeopardy: (1) physiological deconditioning (which in some aspects is still unknown and unpreventable), (2) psychological stress, and (3) ionizing radiation. This latter risk is due to exposure of crew members for extended time to the highly unpredictable and potentially lethal radiations of open space. Any gains in shortening mission duration would reap equivalent or greater benefits for these crew concerns. Dr. Chang-Diaz has applied his training and expertise (Ph.D. from Massachusetts Institute of Technology in applied plasma physics) toward development of continuous rocket propulsion which would offer great time advantages in travel, and also more launch options than are now available. He clearly explained the enormous gains from a relatively low thrust accelerative force applied essentially continuously versus the high, but short-lived propulsion of present chemical rockets. In fact, such spacecraft could be powered throughout the mission, accelerating to approximately the midpoint and decelerating during the latter half. This would not only provide some level of gravity (acceleration) throughout the mission but also allow very high velocities to be achieved, thus saving many months of travel time. In proposing the design of such a spacecraft propulsion system, Dr. Chang-Diaz was quick to acknowledge the need for a large power source, which undoubtedly must be nuclear fueled at the solar distances involved. He calls his system the Variable Specific Impulse Magnetoplasma Rocket (VASIMR). The other major ingredient is a mass (deuterium, which could also function as a radiation shield for crews) for energizing into the ultra hot, high velocity exhaust plasma. He foresees models now functional in the laboratory soon to be tested in space. In fact, some of these concepts have already been tried there. His optimism and determination would have operational rockets in the next decades.

All varieties of encoding variability are not created equal: Separating variable processing from variable tasks

PubMed Central

Huff, Mark J.; Bodner, Glen E.

2014-01-01

Whether encoding variability facilitates memory is shown to depend on whether item-specific and relational processing are both performed across study blocks, and whether study items are weakly versus strongly related. Variable-processing groups studied a word list once using an item-specific task and once using a relational task. Variable-task groups’ two different study tasks recruited the same type of processing each block. Repeated-task groups performed the same study task each block. Recall and recognition were greatest in the variable-processing group, but only with weakly related lists. A variable-processing benefit was also found when task-based processing and list-type processing were complementary (e.g., item-specific processing of a related list) rather than redundant (e.g., relational processing of a related list). That performing both item-specific and relational processing across trials, or within a trial, yields encoding-variability benefits may help reconcile decades of contradictory findings in this area. PMID:25018583

A Call to Standardize Preanalytic Data Elements for Biospecimens, Part II.

PubMed

Robb, James A; Bry, Lynn; Sluss, Patrick M; Wagar, Elizabeth A; Kennedy, Mary F

2015-09-01

Biospecimens must have appropriate clinical annotation (data) to ensure optimal quality for both patient care and research. Additional clinical preanalytic variables are the focus of this continuing study. To complete the identification of the essential preanalytic variables (data fields) that can, and in some instances should, be attached to every collected biospecimen by adding the additional specific variables for clinical chemistry and microbiology to our original 170 variables. The College of American Pathologists Diagnostic Intelligence and Health Information Technology Committee sponsored a second Biorepository Working Group to complete the list of preanalytic variables for annotating biospecimens. Members of the second Biorepository Working Group are experts in clinical pathology and microbiology. Additional preanalytic area-specific variables were identified and ranked along with definitions and potential negative impacts if the variable is not attached to the biospecimen. The draft manuscript was reviewed by additional national and international stakeholders. Four additional required preanalytic variables were identified specifically for clinical chemistry and microbiology biospecimens that can be used as a guide for site-specific implementation into patient care and research biorepository processes. In our collective experience, selecting which of the many preanalytic variables to attach to any specific set of biospecimens used for patient care and/or research is often difficult. The additional ranked list should be of practical benefit when selecting preanalytic variables for a given biospecimen collection.

Spatial and temporal variation in plant hydraulic traits and their relevance for climate change impacts on vegetation.

PubMed

Anderegg, William R L

2015-02-01

Plant hydraulics mediate terrestrial woody plant productivity, influencing global water, carbon, and biogeochemical cycles, as well as ecosystem vulnerability to drought and climate change. While inter-specific differences in hydraulic traits are widely documented, intra-specific hydraulic variability is less well known and is important for predicting climate change impacts. Here, I present a conceptual framework for this intra-specific hydraulic trait variability, reviewing the mechanisms that drive variability and the consequences for vegetation response to climate change. I performed a meta-analysis on published studies (n = 33) of intra-specific variation in a prominent hydraulic trait - water potential at which 50% stem conductivity is lost (P50) - and compared this variation to inter-specific variability within genera and plant functional types used by a dynamic global vegetation model. I found that intra-specific variability is of ecologically relevant magnitudes, equivalent to c. 33% of the inter-specific variability within a genus, and is larger in angiosperms than gymnosperms, although the limited number of studies highlights that more research is greatly needed. Furthermore, plant functional types were poorly situated to capture key differences in hydraulic traits across species, indicating a need to approach prediction of drought impacts from a trait-based, rather than functional type-based perspective.

LineageSpecificSeqgen: generating sequence data with lineage-specific variation in the proportion of variable sites

PubMed Central

Grievink, Liat Shavit; Penny, David; Hendy, Mike D; Holland, Barbara R

2009-01-01

Correction to Shavit Grievink L, Penny D, Hendy MD, Holland BR: LineageSpecificSeqgen: generating sequence data with lineage-specific variation in the proportion of variable sites. BMC Evol Biol 2008, 8(1):317.

The Association between Tax Structure and Cigarette Price Variability: Findings from the International Tobacco Control Policy Evaluation (ITC) Project

PubMed Central

Shang, Ce; Chaloupka, Frank J.; Fong, Geoffrey T; Thompson, Mary; O’Connor, Richard J

2015-01-01

Background Recent studies have shown that more opportunities exist for tax avoidance when cigarette excise tax structure departs from a uniform specific structure. However, the association between tax structure and cigarette price variability has not been thoroughly studied in the existing literature. Objective To examine how cigarette tax structure is associated with price variability. The variability of self-reported prices is measured using the ratios of differences between higher and lower prices to the median price such as the IQR-to-median ratio. Methods We used survey data taken from the International Tobacco Control Policy Evaluation (ITC) Project in 17 countries to conduct the analysis. Cigarette prices were derived using individual purchase information and aggregated to price variability measures for each surveyed country and wave. The effect of tax structures on price variability was estimated using Generalised Estimating Equations after adjusting for year and country attributes. Findings Our study provides empirical evidence of a relationship between tax structure and cigarette price variability. We find that, compared to the specific uniform tax structure, mixed uniform and tiered (specific, ad valorem or mixed) structures are associated with greater price variability (p≤0.01). Moreover, while a greater share of the specific component in total excise taxes is associated with lower price variability (p≤0.05), a tiered tax structure is associated with greater price variability (p≤0.01). The results suggest that a uniform and specific tax structure is the most effective tax structure for reducing tobacco consumption and prevalence by limiting price variability and decreasing opportunities for tax avoidance. PMID:25855641

Feasibility of Reusable Continuous Thrust Spacecraft for Cargo Resupply Missions to Mars

NASA Astrophysics Data System (ADS)

Rabotin, C. B.

Continuous thrust propulsion systems benefit from a much greater efficiency in vacuum than chemical rockets, at the expense of lower instantaneous thrust and high power requirements. The satellite telecommunications industry, known for greatly emphasizing heritage over innovation, now uses electric propulsion for station keeping on a number of spacecraft, and for orbit raising for some smaller satellites, such as the Boeing 702SP platform. Only a few interplanetary missions have relied on continuous thrust for most of their mission, such as ESA's 367 kg SMART-1 and NASA's 1217 kg Dawn mission. The high specific impulse of these continuous thrust engines should make them suitable for transportation of heavy payloads to inner solar system destinations in such a way to limit the dependency on heavy rocket launches. Additionally, such spacecraft should be able to perform orbital insertions at destination in order to deliver the cargo directly in a desired orbit. An example application is designing round-trip missions to Mars to support exploration and eventually colonization. This research investigates the feasibility of return journeys to Mars based on the performance of existing or in-development continuous thrust propulsion systems. In order to determine the business viability of such missions, an emphasis is made on the time of flight during different parts of the mission, the relative velocity with respect to the destination planet, and the fuel requirements. The study looks at the applicability for interplanetary mission design of simple control laws for efficient correction of orbital elements, and of thrusting purely in velocity or anti-velocity direction. The simulations explore different configurations of continuous thrusting technologies using a patched-conics approach. In addition, all simulation scenarios facilitate escape from planetary gravity wells as the initial spacecraft orbit is highly elliptical, both around the Earth and around Mars. This work does not include any optimal trajectory design. For this research, a highly configurable orbit propagation software with SPICE ephemerides was developed from scratch in Go, a modern compiled computer language. The outcome of this research is that simple orbital element control laws do not lead to more efficient or faster interplanetary transfers. In addition, spiraling out of Earth's gravity wells requires a substantial amount of time despite starting from a highly elliptical orbit, and even with clustered high thrust engines like the VASIMR VX-200. Further investigation should look into hybrid solutions with a chemical engine for departing Earth; outbound spirals from Mars take a more reasonable amount of time.

The association between tax structure and cigarette price variability: findings from the ITC Project.

PubMed

Shang, Ce; Chaloupka, Frank J; Fong, Geoffrey T; Thompson, Mary; O'Connor, Richard J

2015-07-01

Recent studies have shown that more opportunities exist for tax avoidance when cigarette excise tax structure departs from a uniform specific structure. However, the association between tax structure and cigarette price variability has not been thoroughly studied in the existing literature. To examine how cigarette tax structure is associated with price variability. The variability of self-reported prices is measured using the ratios of differences between higher and lower prices to the median price such as the IQR-to-median ratio. We used survey data taken from the International Tobacco Control Policy Evaluation (ITC) Project in 17 countries to conduct the analysis. Cigarette prices were derived using individual purchase information and aggregated to price variability measures for each surveyed country and wave. The effect of tax structures on price variability was estimated using Generalised Estimating Equations after adjusting for year and country attributes. Our study provides empirical evidence of a relationship between tax structure and cigarette price variability. We find that, compared to the specific uniform tax structure, mixed uniform and tiered (specific, ad valorem or mixed) structures are associated with greater price variability (p≤0.01). Moreover, while a greater share of the specific component in total excise taxes is associated with lower price variability (p≤0.05), a tiered tax structure is associated with greater price variability (p≤0.01). The results suggest that a uniform and specific tax structure is the most effective tax structure for reducing tobacco consumption and prevalence by limiting price variability and decreasing opportunities for tax avoidance. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Social work perspectives on human behavior.

PubMed

Wodarski, J S

1993-01-01

This manuscript addresses recent developments in human behavior research that are relevant to social work practice. Specific items addressed are biological aspects of behavior, life span development, cognitive variables, the self-efficacy learning process, the perceptual process, the exchange model, group level variables, macro level variables, and gender and ethnic-racial variables. Where relevant, specific applications to social work practice are provided.

Distribution and predictors of wing shape and size variability in three sister species of solitary bees

PubMed Central

Prunier, Jérôme G.; Dewulf, Alexandre; Kuhlmann, Michael; Michez, Denis

2017-01-01

Morphological traits can be highly variable over time in a particular geographical area. Different selective pressures shape those traits, which is crucial in evolutionary biology. Among these traits, insect wing morphometry has already been widely used to describe phenotypic variability at the inter-specific level. On the contrary, fewer studies have focused on intra-specific wing morphometric variability. Yet, such investigations are relevant to study potential convergences of variation that could highlight micro-evolutionary processes. The recent sampling and sequencing of three solitary bees of the genus Melitta across their entire species range provides an excellent opportunity to jointly analyse genetic and morphometric variability. In the present study, we first aim to analyse the spatial distribution of the wing shape and centroid size (used as a proxy for body size) variability. Secondly, we aim to test different potential predictors of this variability at both the intra- and inter-population levels, which includes genetic variability, but also geographic locations and distances, elevation, annual mean temperature and precipitation. The comparison of spatial distribution of intra-population morphometric diversity does not reveal any convergent pattern between species, thus undermining the assumption of a potential local and selective adaptation at the population level. Regarding intra-specific wing shape differentiation, our results reveal that some tested predictors, such as geographic and genetic distances, are associated with a significant correlation for some species. However, none of these predictors are systematically identified for the three species as an important factor that could explain the intra-specific morphometric variability. As a conclusion, for the three solitary bee species and at the scale of this study, our results clearly tend to discard the assumption of the existence of a common pattern of intra-specific signal/structure within the intra-specific wing shape and body size variability. PMID:28273178

The Influence of Culture-Specific Personality Traits on the Development of Delinquency in At-Risk Youth.

PubMed

Tong, Tat Seng; Ku, Lisbeth; Zaroff, Charles Mark

2016-04-01

The association between culture-specific personality variables and family factors, and juvenile delinquency, was assessed in a sample of 402 adolescents of Chinese ethnicity between 12 and 17 years of age (Mage = 15.13, SD = 1.41; 135 girls), a subgroup of whom were considered at risk for juvenile delinquency owing to addictive behavior tendencies. Culture-specific personality variables were assessed using the Chinese Personality Assessment Inventory-Adolescent version Interpersonal Relatedness factor. The General Function subscale of the Chinese version of the Family Assessment Device was utilized to assess the influence of perceived levels of family functioning. Both culture-specific personality variables and non-culture-specific familial factors were significantly and negatively associated with self-reported juvenile delinquency (p < .001). However, in a sample of at-risk adolescents, only a culture-specific variable measuring orientation toward the family was able to predict self-reported juvenile delinquency (p < .001). Implications of the current results are discussed. © The Author(s) 2014.

Examining Differences between Students with Specific Learning Disabilities and Those with Specific Language Disorders on Cognition, Emotions and Psychopathology

ERIC Educational Resources Information Center

Filippatou, Diamanto; Dimitropoulou, Panagiota; Sideridis, Georgios

2009-01-01

The purpose of the present study was to investigate the differences between students with LD and SLI on emotional psychopathology and cognitive variables. In particular, the study examined whether cognitive, emotional, and psychopathology variables are significant discriminatory variables of speech and language disordered groups versus those…

Abbreviation as a Reflection of Terms Variability in Language for Specific Purposes: Translational Features (Terminology Case Study in German, English, Kazakh, and Russia)

ERIC Educational Resources Information Center

Beisembayeva, Gulshat Z.; Yeskindirova, Manshuk Z.; Tulebayeva, Samal A.

2016-01-01

The range of modern dynamic social changes, globalization of world powers' economic cooperation, acceleration of technocratic processes have widespread impact on term systems' variability in language, in particular, on terminological variability for specific purposes. This globalized extra-linguistic factor provokes avalanche growth of…

Surgeon and type of anesthesia predict variability in surgical procedure times.

PubMed

Strum, D P; Sampson, A R; May, J H; Vargas, L G

2000-05-01

Variability in surgical procedure times increases the cost of healthcare delivery by increasing both the underutilization and overutilization of expensive surgical resources. To reduce variability in surgical procedure times, we must identify and study its sources. Our data set consisted of all surgeries performed over a 7-yr period at a large teaching hospital, resulting in 46,322 surgical cases. To study factors associated with variability in surgical procedure times, data mining techniques were used to segment and focus the data so that the analyses would be both technically and intellectually feasible. The data were subdivided into 40 representative segments of manageable size and variability based on headers adopted from the common procedural terminology classification. Each data segment was then analyzed using a main-effects linear model to identify and quantify specific sources of variability in surgical procedure times. The single most important source of variability in surgical procedure times was surgeon effect. Type of anesthesia, age, gender, and American Society of Anesthesiologists risk class were additional sources of variability. Intrinsic case-specific variability, unexplained by any of the preceding factors, was found to be highest for shorter surgeries relative to longer procedures. Variability in procedure times among surgeons was a multiplicative function (proportionate to time) of surgical time and total procedure time, such that as procedure times increased, variability in surgeons' surgical time increased proportionately. Surgeon-specific variability should be considered when building scheduling heuristics for longer surgeries. Results concerning variability in surgical procedure times due to factors such as type of anesthesia, age, gender, and American Society of Anesthesiologists risk class may be extrapolated to scheduling in other institutions, although specifics on individual surgeons may not. This research identifies factors associated with variability in surgical procedure times, knowledge of which may ultimately be used to improve surgical scheduling and operating room utilization.

Mission Advantages of Constant Power, Variable Isp Electrostatic Thrusters

NASA Technical Reports Server (NTRS)

Oleson, Steven R.

2000-01-01

Electric propulsion has moved from station-keeping capability for spacecraft to primary propulsion with the advent of both the Deep Space One asteroid flyby and geosynchronous spacecraft orbit insertion. In both cases notably more payload was delivered than would have been possible with chemical propulsion. To provide even greater improvements electrostatic thruster performance could be varied in specific impulse, but kept at constant power to provide better payload or trip time performance for different mission phases. Such variable specific impulse mission applications include geosynchronous and low earth orbit spacecraft stationkeeping and orbit insertion, geosynchronous reusable tug missions, and interplanetary probes. The application of variable specific impulse devices is shown to add from 5 to 15% payload for these missions. The challenges to building such devices include variable voltage power supplies and extending fuel throughput capabilities across the specific impulse range.

Statistical Analysis for Multisite Trials Using Instrumental Variables with Random Coefficients

ERIC Educational Resources Information Center

Raudenbush, Stephen W.; Reardon, Sean F.; Nomi, Takako

2012-01-01

Multisite trials can clarify the average impact of a new program and the heterogeneity of impacts across sites. Unfortunately, in many applications, compliance with treatment assignment is imperfect. For these applications, we propose an instrumental variable (IV) model with person-specific and site-specific random coefficients. Site-specific IV…

Exemplar Variability Facilitates Retention of Word Learning by Children with Specific Language Impairment

ERIC Educational Resources Information Center

Aguilar, Jessica M.; Plante, Elena; Sandoval, Michelle

2018-01-01

Purpose: Variability in the input plays an important role in language learning. The current study examined the role of object variability for new word learning by preschoolers with specific language impairment (SLI). Method: Eighteen 4- and 5-year-old children with SLI were taught 8 new words in 3 short activities over the course of 3 sessions.…

The Roles of Cognitive and Language Abilities in Predicting Decoding and Reading Comprehension: Comparisons of Dyslexia and Specific Language Impairment

ERIC Educational Resources Information Center

Lauterbach, Alexandra A.; Park, Yujeong; Lombardino, Linda J.

2017-01-01

This study aimed to (a) explore the roles of cognitive and language variables in predicting reading abilities of two groups of individuals with reading disabilities (i.e., dyslexia and specific language impairment) and (b) examine which variable(s) is the most predictive in differentiating two groups. Inclusion/exclusion criteria applied to…

A site specific model and analysis of the neutral somatic mutation rate in whole-genome cancer data.

PubMed

Bertl, Johanna; Guo, Qianyun; Juul, Malene; Besenbacher, Søren; Nielsen, Morten Muhlig; Hornshøj, Henrik; Pedersen, Jakob Skou; Hobolth, Asger

2018-04-19

Detailed modelling of the neutral mutational process in cancer cells is crucial for identifying driver mutations and understanding the mutational mechanisms that act during cancer development. The neutral mutational process is very complex: whole-genome analyses have revealed that the mutation rate differs between cancer types, between patients and along the genome depending on the genetic and epigenetic context. Therefore, methods that predict the number of different types of mutations in regions or specific genomic elements must consider local genomic explanatory variables. A major drawback of most methods is the need to average the explanatory variables across the entire region or genomic element. This procedure is particularly problematic if the explanatory variable varies dramatically in the element under consideration. To take into account the fine scale of the explanatory variables, we model the probabilities of different types of mutations for each position in the genome by multinomial logistic regression. We analyse 505 cancer genomes from 14 different cancer types and compare the performance in predicting mutation rate for both regional based models and site-specific models. We show that for 1000 randomly selected genomic positions, the site-specific model predicts the mutation rate much better than regional based models. We use a forward selection procedure to identify the most important explanatory variables. The procedure identifies site-specific conservation (phyloP), replication timing, and expression level as the best predictors for the mutation rate. Finally, our model confirms and quantifies certain well-known mutational signatures. We find that our site-specific multinomial regression model outperforms the regional based models. The possibility of including genomic variables on different scales and patient specific variables makes it a versatile framework for studying different mutational mechanisms. Our model can serve as the neutral null model for the mutational process; regions that deviate from the null model are candidates for elements that drive cancer development.

PROMISE: a tool to identify genomic features with a specific biologically interesting pattern of associations with multiple endpoint variables.

PubMed

Pounds, Stan; Cheng, Cheng; Cao, Xueyuan; Crews, Kristine R; Plunkett, William; Gandhi, Varsha; Rubnitz, Jeffrey; Ribeiro, Raul C; Downing, James R; Lamba, Jatinder

2009-08-15

In some applications, prior biological knowledge can be used to define a specific pattern of association of multiple endpoint variables with a genomic variable that is biologically most interesting. However, to our knowledge, there is no statistical procedure designed to detect specific patterns of association with multiple endpoint variables. Projection onto the most interesting statistical evidence (PROMISE) is proposed as a general procedure to identify genomic variables that exhibit a specific biologically interesting pattern of association with multiple endpoint variables. Biological knowledge of the endpoint variables is used to define a vector that represents the biologically most interesting values for statistics that characterize the associations of the endpoint variables with a genomic variable. A test statistic is defined as the dot-product of the vector of the observed association statistics and the vector of the most interesting values of the association statistics. By definition, this test statistic is proportional to the length of the projection of the observed vector of correlations onto the vector of most interesting associations. Statistical significance is determined via permutation. In simulation studies and an example application, PROMISE shows greater statistical power to identify genes with the interesting pattern of associations than classical multivariate procedures, individual endpoint analyses or listing genes that have the pattern of interest and are significant in more than one individual endpoint analysis. Documented R routines are freely available from www.stjuderesearch.org/depts/biostats and will soon be available as a Bioconductor package from www.bioconductor.org.

Family-related predictors of body weight and weight-related behaviours among children and adolescents: a systematic umbrella review.

PubMed

Cislak, A; Safron, M; Pratt, M; Gaspar, T; Luszczynska, A

2012-05-01

This umbrella review analysed the relationships between family variables and child/adolescent body weight, diet and physical activity. In line with theories of health behaviour change, it was assumed that behaviour-specific family variables (i.e. beliefs, perceptions and practices referring to food intake or physical activity) would have stronger support than more general family variables (i.e. socio-economic status or general parental practices). Data obtained from 18 systematic reviews (examining 375 quantitative studies) were analysed. Reviews of experimental trials generally supported the effectiveness of reward/positive reinforcement parental strategies, parental involvement in treatment or prevention programmes, and cognitive-behavioural treatment in reducing child/adolescent body mass and/or obesity. Results across reviews of correlational studies indicated that healthy nutrition of children/adolescents was related to only one parental practice (parental monitoring), but was associated with several behaviour-specific family variables (e.g. a lack of restrictive control over food choices, high intake of healthy foods and low intake of unhealthy foods by parents and siblings, low pressure to consume foods). With regard to adolescent physical activity, stronger support was also found for behaviour-specific variables (e.g. physical activity of siblings), and for certain socio-economic variables (e.g. parental education). Child and adolescent obesity prevention programmes should account for behaviour-specific family variables. © 2011 Blackwell Publishing Ltd.

Homotopy method for optimization of variable-specific-impulse low-thrust trajectories

NASA Astrophysics Data System (ADS)

Chi, Zhemin; Yang, Hongwei; Chen, Shiyu; Li, Junfeng

2017-11-01

The homotopy method has been used as a useful tool in solving fuel-optimal trajectories with constant-specific-impulse low thrust. However, the specific impulse is often variable for many practical solar electric power-limited thrusters. This paper investigates the application of the homotopy method for optimization of variable-specific-impulse low-thrust trajectories. Difficulties arise when the two commonly-used homotopy functions are employed for trajectory optimization. The optimal power throttle level and the optimal specific impulse are coupled with the commonly-used quadratic and logarithmic homotopy functions. To overcome these difficulties, a modified logarithmic homotopy function is proposed to serve as a gateway for trajectory optimization, leading to decoupled expressions of both the optimal power throttle level and the optimal specific impulse. The homotopy method based on this homotopy function is proposed. Numerical simulations validate the feasibility and high efficiency of the proposed method.

Local nutrient regimes determine site-specific environmental triggers of cyanobacterial and microcystin variability in urban lakes

NASA Astrophysics Data System (ADS)

Sinang, S. C.; Reichwaldt, E. S.; Ghadouani, A.

2014-10-01

Toxic cyanobacterial blooms in urban lakes present serious health hazards to humans and animals and require effective management strategies. In the management of toxic cyanobacteria blooms, understanding the roles of environmental factors is crucial. To date, a range of environmental factors have been proposed as potential triggers for the spatiotemporal variability of cyanobacterial biomass and microcystins in freshwater systems. However, the environmental triggers of cyanobacteria and microcystin variability remain a subject of debate due to contrasting findings. This issue has raised the question if the environmental triggers are site-specific and unique between water bodies. In this study, we investigated the site-specificity of environmental triggers for cyanobacterial bloom and cyanotoxins dynamics. Our study suggests that cyanobacterial dominance and cyanobacterial microcystin content variability were significantly correlated to phosphorus and iron concentrations. However, the correlations between phosphorus and iron with cyanobacterial biomass and microcystin variability were not consistent between lakes, thus suggesting a site specificity of these environmental factors. The discrepancies in the correlations could be explained by differences in local nutrient concentration and the cyanobacterial community in the systems. The findings of this study suggest that identification of site-specific environmental factors under unique local conditions is an important strategy to enhance positive outcomes in cyanobacterial bloom control measures.

PROMISE: a tool to identify genomic features with a specific biologically interesting pattern of associations with multiple endpoint variables

PubMed Central

Pounds, Stan; Cheng, Cheng; Cao, Xueyuan; Crews, Kristine R.; Plunkett, William; Gandhi, Varsha; Rubnitz, Jeffrey; Ribeiro, Raul C.; Downing, James R.; Lamba, Jatinder

2009-01-01

Motivation: In some applications, prior biological knowledge can be used to define a specific pattern of association of multiple endpoint variables with a genomic variable that is biologically most interesting. However, to our knowledge, there is no statistical procedure designed to detect specific patterns of association with multiple endpoint variables. Results: Projection onto the most interesting statistical evidence (PROMISE) is proposed as a general procedure to identify genomic variables that exhibit a specific biologically interesting pattern of association with multiple endpoint variables. Biological knowledge of the endpoint variables is used to define a vector that represents the biologically most interesting values for statistics that characterize the associations of the endpoint variables with a genomic variable. A test statistic is defined as the dot-product of the vector of the observed association statistics and the vector of the most interesting values of the association statistics. By definition, this test statistic is proportional to the length of the projection of the observed vector of correlations onto the vector of most interesting associations. Statistical significance is determined via permutation. In simulation studies and an example application, PROMISE shows greater statistical power to identify genes with the interesting pattern of associations than classical multivariate procedures, individual endpoint analyses or listing genes that have the pattern of interest and are significant in more than one individual endpoint analysis. Availability: Documented R routines are freely available from www.stjuderesearch.org/depts/biostats and will soon be available as a Bioconductor package from www.bioconductor.org. Contact: stanley.pounds@stjude.org Supplementary information: Supplementary data are available at Bioinformatics online. PMID:19528086

Is case-specificity content-specificity? An analysis of data from extended-matching questions.

PubMed

Dory, Valerie; Gagnon, Robert; Charlin, Bernard

2010-03-01

Case-specificity, i.e., variability of a subject's performance across cases, has been a consistent finding in medical education. It has important implications for assessment validity and reliability. Its root causes remain a matter of discussion. One hypothesis, content-specificity, links variability of performance to variable levels of relevant knowledge. Extended-matching items (EMIs) are an ideal format to test this hypothesis as items are grouped by topic. If differences pertaining to content knowledge are the main cause of case-specificity, variability across topics should be high and variability across items within the same topic low. We used generalisability analysis on results of a written test composed of 159 EMIs sat by two cohorts of general practice trainees at one university. Two hundred and twenty-seven trainees took part. The variance component attributed to subjects was small. Variance attributed to topics was smaller than variance attributed to items. The main source of error was interaction between subjects and items, accounting for two-thirds of error. The generalisability D study revealed that for the same total number of items, increasing the number of topics results in a higher G coefficient than increasing the number of items per topic. Topical knowledge does not seem to explain case-specificity observed in our data. Structure of knowledge and reasoning strategy may be more important, in particular pattern-recognition which EMIs were designed to elicit. The causal explanations of case-specificity may be dependent on test format. Increasing the number of topics with fewer items each would increase reliability but also testing time.

Specific gravity of hybrid poplars in the north-central region, USA: within-tree variability and site × genotype effects

Treesearch

William L. Headlee; Ronald S. Jr. Zalesny; Richard B. Hall; Edmund O. Bauer; Bradford Bender; Bruce A. Birr; Raymond O. Miller; Jesse A. Randall; Adam H. Wiese

2013-01-01

Specific gravity is an important consideration for traditional uses of hybrid poplars for pulp and solid wood products, as well as for biofuels and bioenergy production. While specific gravity has been shown to be under strong genetic control and subject to within-tree variability, the role of genotype × environment interactions is poorly understood. Most...

Exploratory Analysis of the Effects of Anxiety on Specific Quantifiable Variables of African-American High School Students Enrolled in Advanced Academics

ERIC Educational Resources Information Center

James, Carmela N.

2013-01-01

The purpose of this study was to examine the attrition rate of the African American high school student enrolled in advanced academics by looking at the effects of specific quantifiable variables on state-trait anxiety scores. More specifically, this study was concerned with the influence of demographic and school related factors on the…

Automatic Methods and Tools for the Verification of Real Time Systems

DTIC Science & Technology

1997-07-31

real - time systems . This was accomplished by extending techniques, based on automata theory and temporal logic, that have been successful for the verification of time-independent reactive systems. As system specification lanmaage for embedded real - time systems , we introduced hybrid automata, which equip traditional discrete automata with real-numbered clock variables and continuous environment variables. As requirements specification languages, we introduced temporal logics with clock variables for expressing timing constraints.

Uncertainty analysis of the simulations of effects of discharging treated wastewater to the Red River of the North at Fargo, North Dakota, and Moorhead, Minnesota

USGS Publications Warehouse

Wesolowski, Edwin A.

1996-01-01

Two separate studies to simulate the effects of discharging treated wastewater to the Red River of the North at Fargo, North Dakota, and Moorhead, Minnesota, have been completed. In the first study, the Red River at Fargo Water-Quality Model was calibrated and verified for icefree conditions. In the second study, the Red River at Fargo Ice-Cover Water-Quality Model was verified for ice-cover conditions.To better understand and apply the Red River at Fargo Water-Quality Model and the Red River at Fargo Ice-Cover Water-Quality Model, the uncertainty associated with simulated constituent concentrations and property values was analyzed and quantified using the Enhanced Stream Water Quality Model-Uncertainty Analysis. The Monte Carlo simulation and first-order error analysis methods were used to analyze the uncertainty in simulated values for six constituents and properties at sites 5, 10, and 14 (upstream to downstream order). The constituents and properties analyzed for uncertainty are specific conductance, total organic nitrogen (reported as nitrogen), total ammonia (reported as nitrogen), total nitrite plus nitrate (reported as nitrogen), 5-day carbonaceous biochemical oxygen demand for ice-cover conditions and ultimate carbonaceous biochemical oxygen demand for ice-free conditions, and dissolved oxygen. Results are given in detail for both the ice-cover and ice-free conditions for specific conductance, total ammonia, and dissolved oxygen.The sensitivity and uncertainty of the simulated constituent concentrations and property values to input variables differ substantially between ice-cover and ice-free conditions. During ice-cover conditions, simulated specific-conductance values are most sensitive to the headwatersource specific-conductance values upstream of site 10 and the point-source specific-conductance values downstream of site 10. These headwater-source and point-source specific-conductance values also are the key sources of uncertainty. Simulated total ammonia concentrations are most sensitive to the point-source total ammonia concentrations at all three sites. Other input variables that contribute substantially to the variability of simulated total ammonia concentrations are the headwater-source total ammonia and the instream reaction coefficient for biological decay of total ammonia to total nitrite. Simulated dissolved-oxygen concentrations at all three sites are most sensitive to headwater-source dissolved-oxygen concentration. This input variable is the key source of variability for simulated dissolved-oxygen concentrations at sites 5 and 10. Headwatersource and point-source dissolved-oxygen concentrations are the key sources of variability for simulated dissolved-oxygen concentrations at site 14.During ice-free conditions, simulated specific-conductance values at all three sites are most sensitive to the headwater-source specific-conductance values. Headwater-source specificconductance values also are the key source of uncertainty. The input variables to which total ammonia and dissolved oxygen are most sensitive vary from site to site and may or may not correspond to the input variables that contribute the most to the variability. The input variables that contribute the most to the variability of simulated total ammonia concentrations are pointsource total ammonia, instream reaction coefficient for biological decay of total ammonia to total nitrite, and Manning's roughness coefficient. The input variables that contribute the most to the variability of simulated dissolved-oxygen concentrations are reaeration rate, sediment oxygen demand rate, and headwater-source algae as chlorophyll a.

Pointwise Partial Information Decomposition Using the Specificity and Ambiguity Lattices

NASA Astrophysics Data System (ADS)

Finn, Conor; Lizier, Joseph

2018-04-01

What are the distinct ways in which a set of predictor variables can provide information about a target variable? When does a variable provide unique information, when do variables share redundant information, and when do variables combine synergistically to provide complementary information? The redundancy lattice from the partial information decomposition of Williams and Beer provided a promising glimpse at the answer to these questions. However, this structure was constructed using a much criticised measure of redundant information, and despite sustained research, no completely satisfactory replacement measure has been proposed. In this paper, we take a different approach, applying the axiomatic derivation of the redundancy lattice to a single realisation from a set of discrete variables. To overcome the difficulty associated with signed pointwise mutual information, we apply this decomposition separately to the unsigned entropic components of pointwise mutual information which we refer to as the specificity and ambiguity. This yields a separate redundancy lattice for each component. Then based upon an operational interpretation of redundancy, we define measures of redundant specificity and ambiguity enabling us to evaluate the partial information atoms in each lattice. These atoms can be recombined to yield the sought-after multivariate information decomposition. We apply this framework to canonical examples from the literature and discuss the results and the various properties of the decomposition. In particular, the pointwise decomposition using specificity and ambiguity satisfies a chain rule over target variables, which provides new insights into the so-called two-bit-copy example.

Adoption of site-specific variable rate sprinkler irrigation systems

USDA-ARS?s Scientific Manuscript database

More than twenty years of private and public research on site-specific variable-rate sprinkler irrigation (SS-VRI) technology has resulted in limited commercial adoption of the technology. Competing patents, liability and proprietary software have affected industry’s willingness to move into a new t...

Gender-specific responses to climate variability in a semi-arid ecosystem in northern Benin.

PubMed

Dah-Gbeto, Afiavi P; Villamor, Grace B

2016-12-01

Highly erratic rainfall patterns in northern Benin complicate the ability of rural farmers to engage in subsistence agriculture. This research explores gender-specific responses to climate variability in the context of agrarian Benin through a household survey (n = 260) and an experimental gaming exercise among a subset of the survey respondents. Although men and women from the sample population are equally aware of climate variability and share similar coping strategies, their specific land-use strategies, preferences, and motivations are distinct. Over the long term, these differences would likely lead to dissimilar coping strategies and vulnerability to the effects of climate change. Examination of gender-specific land-use responses to climate change and anticipatory learning can enhance efforts to improve adaptability and resilience among rural subsistence farmers.

Jury Selection in Child Sex Abuse Trials: A Case Analysis

ERIC Educational Resources Information Center

Cramer, Robert J.; Adams, Desiree D.; Brodsky, Stanley L.

2009-01-01

Child sex abuse cases have been the target of considerable psycho-legal research. The present paper offers an analysis of psychological constructs for jury selection in child sex abuse cases from the defense perspective. The authors specifically delineate general and case-specific jury selection variables. General variables include…

Integration of aerial imaging and variable-rate technology for site-specific aerial herbicide application

USDA-ARS?s Scientific Manuscript database

As remote sensing and variable rate technology are becoming more available for aerial applicators, practical methodologies on effective integration of these technologies are needed for site-specific aerial applications of crop production and protection materials. The objectives of this study were to...

Admission Criteria and Other Variables as Predictors of Business Student Graduation

ERIC Educational Resources Information Center

Truell, Allen D.; Woosley, Sherry

2008-01-01

Previous research has largely overlooked discipline specific admission criteria at the undergraduate level and its relationship to student success. Thus, the purpose of this study was to determine if college of business admission criteria and other variables predicted undergraduate college of business student graduation. The specific variables…

Culture-Specific Variables That May Affect Employment Outcomes for Mexican-American Youth with Disabilities.

ERIC Educational Resources Information Center

Meier-Kronick, Nancy

This paper reviews variables specific to the Mexican-American culture that might influence work-related behavior and outcomes for youths with disabilities from this population. Areas covered include: parental/family network; cultural view of disability; religious influences; acculturation levels; language issues; education and employment…

Is Reaction Time Variability in ADHD Mainly at Low Frequencies?

ERIC Educational Resources Information Center

Karalunas, Sarah L.; Huang-Pollock, Cynthia L.; Nigg, Joel T.

2013-01-01

Background: Intraindividual variability in reaction times (RT variability) has garnered increasing interest as an indicator of cognitive and neurobiological dysfunction in children with attention deficit hyperactivity disorder (ADHD). Recent theory and research has emphasized specific low-frequency patterns of RT variability. However, whether…

Resource utilization in home health care: results of a prospective study.

PubMed

Trisolini, M G; Thomas, C P; Cashman, S B; Payne, S M

1994-01-01

Resource utilization in home health care has become an issue of concern due to rising costs and recent initiatives to develop prospective payment systems for home health care. A number of issues remain unresolved for the development of prospective reimbursement in this sector, including the types of variables to be included as payment variables and appropriate measures of resource use. This study supplements previous work on home health case-mix by analyzing the factors affecting one aspect of resource use for skilled nursing visits--visit length--and explores the usefulness of several specially collected variables which are not routinely available in administrative records. A data collection instrument was developed with a focus group of skilled nurses, identifying a range of variables hypothesized to affect visit length. Five categories of variables were studied using multiple regression analysis: provider-related; patient's socio-economic status; patient's clinical status; patient's support services; and visit-specific. The final regression model identifies 9 variables which significantly affect visit time. Five of the 9 are visit-specific variables, a significant finding since these are not routinely collected. Case-mix systems which include visit time as a measure of resource use will need to investigate visit-specific variables, as this study indicates they could have the largest influence on visit time. Two other types of resources used in home health care, supplies and security drivers, were also investigated in less detail.

Perianth organization and intra-specific floral variability.

PubMed

Herrera, J; Arista, M; Ortiz, P L

2008-11-01

Floral symmetry and fusion of perianth parts are factors that contribute to fine-tune the match between flowers and their animal pollination vectors. In the present study, we investigated whether the possession of a sympetalous (fused) corolla and bilateral symmetry of flowers translate into decreased intra-specific variability as a result of natural stabilizing selection exerted by pollinators. Average size of the corolla and intra-specific variability were determined in two sets of southern Spanish entomophilous plant species. In the first set, taxa were paired by family to control for the effect of phylogeny (phylogenetically independent contrasts), whereas in the second set species were selected at random. Flower size data from a previous study (with different species) were also used to test the hypothesis that petal fusion contributes to decrease intra-specific variability. In the phylogenetically independent contrasts, floral symmetry was a significant correlate of intra-specific variation, with bilaterally symmetrical flowers showing more constancy than radially symmetrical flowers (i.e. unsophisticated from a functional perspective). As regards petal fusion, species with fused petals were on average more constant than choripetalous species, but the difference was not statistically significant. The reanalysis of data from a previous study yielded largely similar results, with a distinct effect of symmetry on variability, but no effect of petal fusion. The randomly-chosen species sample, on the other hand, failed to reveal any significant effect of either symmetry or petal fusion on intra-specific variation. The problem of low-statistical power in this kind of analysis, and the difficulty of testing an evolutionary hypothesis that involves phenotypic traits with a high degree of morphological correlation is discussed.

A Comparison of Joint Model and Fully Conditional Specification Imputation for Multilevel Missing Data

ERIC Educational Resources Information Center

Mistler, Stephen A.; Enders, Craig K.

2017-01-01

Multiple imputation methods can generally be divided into two broad frameworks: joint model (JM) imputation and fully conditional specification (FCS) imputation. JM draws missing values simultaneously for all incomplete variables using a multivariate distribution, whereas FCS imputes variables one at a time from a series of univariate conditional…

The Education of a Leader: Educational Credentials and Other Characteristics of Chief Executive Officers

ERIC Educational Resources Information Center

Martelli, Joseph; Abels, Patricia

2010-01-01

The authors identified and described the CEOs of Fortune 500 companies in terms of several education-related and other demographic variables. Specifically, they identified the type and level of degrees earned, including specific majors, and additionally explored several demographic variables, including age, gender and ethnicity. They also…

Performance index for virtual reality phacoemulsification surgery

NASA Astrophysics Data System (ADS)

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

2007-02-01

We have developed a virtual reality (VR) simulator for phacoemulsification (phaco) surgery. The current work aimed at developing a performance index that characterizes the performance of an individual trainee. We recorded measurements of 28 response variables during three iterated surgical sessions in 9 subjects naive to cataract surgery and 6 experienced cataract surgeons, separately for the sculpting phase and the evacuation phase of phacoemulsification surgery. We further defined a specific performance index for a specific measurement variable and a total performance index for a specific trainee. The distribution function for the total performance index was relatively evenly distributed both for the sculpting and the evacuation phase indicating that parametric statistics can be used for comparison of total average performance indices for different groups in the future. The current total performance index for an individual considers all measurement variables included with the same weight. It is possible that a future development of the system will indicate that a better characterization of a trainee can be obtained if the various measurements variables are given specific weights. The currently developed total performance index for a trainee is statistically an independent observation of that particular trainee.

The effect of patient and contextual characteristics on racial/ethnic disparity in breast cancer mortality

PubMed Central

Sposto, Richard; Keegan, Theresa H. M.; Vigen, Cheryl; Kwan, Marilyn L.; Bernstein, Leslie; John, Esther M.; Cheng, Iona; Yang, Juan; Koo, Jocelyn; Kurian, Allison W.; Caan, Bette J.; Lu, Yani; Monroe, Kristine R.; Shariff-Marco, Salma; Gomez, Scarlett Lin; Wu, Anna H.

2016-01-01

Background Racial/ethnic disparity in breast cancer-specific mortality in the U.S. is well documented. We examined whether accounting for racial/ethnic differences in the prevalence of clinical, patient, and lifestyle and contextual factors that are associated with breast cancer-specific mortality can explain this disparity. Methods The California Breast Cancer Survivorship Consortium combined interview data from six California-based breast cancer studies with cancer registry data to create a large racially diverse cohort of women with primary invasive breast cancer. We examined the contribution of variables in a previously reported Cox regression baseline model plus additional contextual, physical activity, body size, and comorbidity variables to the racial/ethnic disparity in breast cancer-specific mortality. Results The cohort comprised 12,098 women. Fifty-four percent were non-Latina Whites, 17% African Americans, 17% Latinas, and 12% Asian Americans. In a model adjusting only for age and study, breast cancer-specific hazard ratios relative to Whites were 1.69 (95% CI 1.46 -1.96), 1.00 (0.84 - 1.19), and 0.52 (0.33 - 0.85) for African Americans, Latinas, and Asian Americans respectively. Adjusting for baseline-model variables decreased disparity primarily by reducing the hazard ratio for African Americans to 1.13 (0.96 - 1.33). The most influential variables were related to disease characteristics, neighborhood socioeconomic status, and smoking status at diagnosis. Other variables had negligible impact on disparity. Conclusions While contextual, physical activity, body size, and comorbidity variables may influence breast cancer-specific mortality, they do not explain racial/ethnic mortality disparity. Impact Other factors besides those investigated here may explain the existing racial/ethnic disparity in mortality. PMID:27197297

Selection of single chain antibody fragments binding to the extracellular domain of 4-1BB receptor by phage display technology.

PubMed

Bagheri, Salman; Yousefi, Mehdi; Safaie Qamsari, Elmira; Riazi-Rad, Farhad; Abolhassani, Mohsen; Younesi, Vahid; Dorostkar, Ruhollah; Movassaghpour, Ali Akbar; Sharifzadeh, Zahra

2017-03-01

The 4-1BB is a surface glycoprotein that pertains to the tumor necrosis factor-receptor family. There is compelling evidence suggesting important roles for 4-1BB in the immune response, including cell activation and proliferation and also cytokine induction. Because of encouraging results of different agonistic monoclonal antibodies against 4-1BB in the treatment of cancer, infectious, and autoimmune diseases, 4-1BB has been suggested as an attractive target for immunotherapy. In this study, single chain variable fragment phage display libraries, Tomlinson I+J, were screened against specific synthetic oligopeptides (peptides I and II) designed from 4-1BB extracellular domain. Five rounds of panning led to selection of four 4-1BB specific single chain variable fragments (PI.12, PI.42, PII.16, and PII.29) which showed specific reaction to relevant peptides in phage enzyme-linked immunosorbent assay. The selected clones were successfully expressed in Escherichia coli Rosetta-gami 2, and their expression was confirmed by western blot analysis. Enzyme-linked immunosorbent assay experiments indicated that these antibodies were able to specifically recognize 4-1BB without any cross-reactivity with other antigens. Flow cytometry analysis demonstrated an acceptable specific binding of the single chain variable fragments to 4-1BB expressed on CCRF-CEM cells, while no binding was observed with an irrelevant antibody. Anti-4-1BB single chain variable fragments enhanced surface CD69 expression and interleukin-2 production in stimulated CCRF-CEM cells which confirmed the agonistic effect of the selected single chain variable fragments. The data from this study have provided a rationale for further experiments involving the biological functions of anti-4-1BB single chain variable fragments in future studies.

The Effects of Model Misspecification and Sample Size on LISREL Maximum Likelihood Estimates.

ERIC Educational Resources Information Center

Baldwin, Beatrice

The robustness of LISREL computer program maximum likelihood estimates under specific conditions of model misspecification and sample size was examined. The population model used in this study contains one exogenous variable; three endogenous variables; and eight indicator variables, two for each latent variable. Conditions of model…

The mortality burden of hourly temperature variability in five capital cities, Australia: Time-series and meta-regression analysis.

PubMed

Cheng, Jian; Xu, Zhiwei; Bambrick, Hilary; Su, Hong; Tong, Shilu; Hu, Wenbiao

2017-12-01

Unstable weather, such as intra- and inter-day temperature variability, can impair the health and shorten the survival time of population around the world. Climate change will cause Earth's surface temperature rise, but has unclear effects on temperature variability, making it urgent to understand the characteristics of the burden of temperature variability on mortality, regionally and nationally. This paper aims to quantify the mortality risk of exposure to short-term temperature variability, estimate the resulting death toll and explore how the strength of temperature variability effects will vary as a function of city-level characteristics. Ten-year (2000-2009) time-series data on temperature and mortality were collected for five largest Australia's cities (Sydney, Melbourne, Brisbane, Perth and Adelaide), collectively registering 708,751 deaths in different climates. Short-term temperature variability was captured and represented as the hourly temperature standard deviation within two days. Three-stage analyses were used to assess the burden of temperature variability on mortality. First, we modelled temperature variability-mortality relation and estimated the relative risk of death for each city, using a time-series quasi-Poisson regression model. Second, we used meta-analysis to pool the city-specific estimates, and meta-regression to explore if some city-level factors will modify the population vulnerability to temperature variability. Finally, we calculated the city-specific deaths attributable to temperature variability, and applied such estimates to the whole of Australia as a reflection of the nation-wide death burden associated with temperature variability. We found evidence of significant associations between temperature variability and mortality in all cities assessed. Deaths associated with each 1°C rise in temperature variability elevated by 0.28% (95% confidence interval (CI): 0.05%, 0.52%) in Melbourne to 1.00% (95%CI: 0.52%, 1.48%) in Brisbane, with a pooled estimate of 0.51% (95%CI: 0.33%, 0.69%) for Australia. Subtropical and temperate regions showed no apparent difference in temperature variability impacts. Meta-regression analyses indicated that the mortality risk could be influenced by city-specific factors: latitude, mean temperature, population density and the prevalence of several chronic diseases. Taking account of contributions from the entire time-series, temperature variability was estimated to account for 0.99% to 3.24% of deaths across cities, with a nation-wide attributable fraction of 1.67% (9.59 deaths per 100, 000 population per year). Hourly temperature variability may be an important risk factor of weather-related deaths and led to a sizeable mortality burden. This study underscores the need for developing specific and effective interventions in Australia to lessen the health consequences of temperature variability. Copyright © 2017. Published by Elsevier Ltd.

Mixed geographically weighted regression (MGWR) model with weighted adaptive bi-square for case of dengue hemorrhagic fever (DHF) in Surakarta

NASA Astrophysics Data System (ADS)

Astuti, H. N.; Saputro, D. R. S.; Susanti, Y.

2017-06-01

MGWR model is combination of linear regression model and geographically weighted regression (GWR) model, therefore, MGWR model could produce parameter estimation that had global parameter estimation, and other parameter that had local parameter in accordance with its observation location. The linkage between locations of the observations expressed in specific weighting that is adaptive bi-square. In this research, we applied MGWR model with weighted adaptive bi-square for case of DHF in Surakarta based on 10 factors (variables) that is supposed to influence the number of people with DHF. The observation unit in the research is 51 urban villages and the variables are number of inhabitants, number of houses, house index, many public places, number of healthy homes, number of Posyandu, area width, level population density, welfare of the family, and high-region. Based on this research, we obtained 51 MGWR models. The MGWR model were divided into 4 groups with significant variable is house index as a global variable, an area width as a local variable and the remaining variables vary in each. Global variables are variables that significantly affect all locations, while local variables are variables that significantly affect a specific location.

Combined model of intrinsic and extrinsic variability for computational network design with application to synthetic biology.

PubMed

Toni, Tina; Tidor, Bruce

2013-01-01

Biological systems are inherently variable, with their dynamics influenced by intrinsic and extrinsic sources. These systems are often only partially characterized, with large uncertainties about specific sources of extrinsic variability and biochemical properties. Moreover, it is not yet well understood how different sources of variability combine and affect biological systems in concert. To successfully design biomedical therapies or synthetic circuits with robust performance, it is crucial to account for uncertainty and effects of variability. Here we introduce an efficient modeling and simulation framework to study systems that are simultaneously subject to multiple sources of variability, and apply it to make design decisions on small genetic networks that play a role of basic design elements of synthetic circuits. Specifically, the framework was used to explore the effect of transcriptional and post-transcriptional autoregulation on fluctuations in protein expression in simple genetic networks. We found that autoregulation could either suppress or increase the output variability, depending on specific noise sources and network parameters. We showed that transcriptional autoregulation was more successful than post-transcriptional in suppressing variability across a wide range of intrinsic and extrinsic magnitudes and sources. We derived the following design principles to guide the design of circuits that best suppress variability: (i) high protein cooperativity and low miRNA cooperativity, (ii) imperfect complementarity between miRNA and mRNA was preferred to perfect complementarity, and (iii) correlated expression of mRNA and miRNA--for example, on the same transcript--was best for suppression of protein variability. Results further showed that correlations in kinetic parameters between cells affected the ability to suppress variability, and that variability in transient states did not necessarily follow the same principles as variability in the steady state. Our model and findings provide a general framework to guide design principles in synthetic biology.

Combined Model of Intrinsic and Extrinsic Variability for Computational Network Design with Application to Synthetic Biology

PubMed Central

Toni, Tina; Tidor, Bruce

2013-01-01

Biological systems are inherently variable, with their dynamics influenced by intrinsic and extrinsic sources. These systems are often only partially characterized, with large uncertainties about specific sources of extrinsic variability and biochemical properties. Moreover, it is not yet well understood how different sources of variability combine and affect biological systems in concert. To successfully design biomedical therapies or synthetic circuits with robust performance, it is crucial to account for uncertainty and effects of variability. Here we introduce an efficient modeling and simulation framework to study systems that are simultaneously subject to multiple sources of variability, and apply it to make design decisions on small genetic networks that play a role of basic design elements of synthetic circuits. Specifically, the framework was used to explore the effect of transcriptional and post-transcriptional autoregulation on fluctuations in protein expression in simple genetic networks. We found that autoregulation could either suppress or increase the output variability, depending on specific noise sources and network parameters. We showed that transcriptional autoregulation was more successful than post-transcriptional in suppressing variability across a wide range of intrinsic and extrinsic magnitudes and sources. We derived the following design principles to guide the design of circuits that best suppress variability: (i) high protein cooperativity and low miRNA cooperativity, (ii) imperfect complementarity between miRNA and mRNA was preferred to perfect complementarity, and (iii) correlated expression of mRNA and miRNA – for example, on the same transcript – was best for suppression of protein variability. Results further showed that correlations in kinetic parameters between cells affected the ability to suppress variability, and that variability in transient states did not necessarily follow the same principles as variability in the steady state. Our model and findings provide a general framework to guide design principles in synthetic biology. PMID:23555205

Egg buoyancy variability in local populations of Atlantic cod (Gadus morhua).

PubMed

Jung, Kyung-Mi; Folkvord, Arild; Kjesbu, Olav Sigurd; Agnalt, Ann Lisbeth; Thorsen, Anders; Sundby, Svein

2012-01-01

Previous studies have found strong evidences for Atlantic cod ( Gadus morhua ) egg retention in fjords, which are caused by the combination of vertical salinity structure, estuarine circulation, and egg specific gravity, supporting small-scaled geographical differentiations of local populations. Here, we assess the variability in egg specific gravity for selected local populations of this species, that is, two fjord-spawning populations and one coastal-spawning population from Northern Norway (66-71°N/10-25°E). Eggs were naturally spawned by raised broodstocks (March to April 2009), and egg specific gravity was measured by a density-gradient column. The phenotype of egg specific gravity was similar among the three local populations. However, the associated variability was greater at the individual level than at the population level. The noted gradual decrease in specific gravity from gastrulation to hatching with an increase just before hatching could be a generic pattern in pelagic marine fish eggs. This study provides needed input to adequately understand and model fish egg dispersal.

Autonomic specificity of basic emotions: evidence from pattern classification and cluster analysis.

PubMed

Stephens, Chad L; Christie, Israel C; Friedman, Bruce H

2010-07-01

Autonomic nervous system (ANS) specificity of emotion remains controversial in contemporary emotion research, and has received mixed support over decades of investigation. This study was designed to replicate and extend psychophysiological research, which has used multivariate pattern classification analysis (PCA) in support of ANS specificity. Forty-nine undergraduates (27 women) listened to emotion-inducing music and viewed affective films while a montage of ANS variables, including heart rate variability indices, peripheral vascular activity, systolic time intervals, and electrodermal activity, were recorded. Evidence for ANS discrimination of emotion was found via PCA with 44.6% of overall observations correctly classified into the predicted emotion conditions, using ANS variables (z=16.05, p<.001). Cluster analysis of these data indicated a lack of distinct clusters, which suggests that ANS responses to the stimuli were nomothetic and stimulus-specific rather than idiosyncratic and individual-specific. Collectively these results further confirm and extend support for the notion that basic emotions have distinct ANS signatures. Copyright © 2010 Elsevier B.V. All rights reserved.

A diabetes-specific enteral formula improves glycemic variability in patients with type 2 diabetes.

PubMed

Alish, Carolyn J; Garvey, W Timothy; Maki, Kevin C; Sacks, Gordon S; Hustead, Deborah S; Hegazi, Refaat A; Mustad, Vikkie A

2010-06-01

Well-controlled studies have demonstrated that inpatient hyperglycemia is an indicator of poor clinical outcomes, but the use of diabetes-specific enteral formulas in hospitalized patients remains a topic of great debate. In two different protocols, postprandial glycemia and insulinemia were measured in 22 subjects with diabetes fed a diabetes-specific or standard formula (protocol 1). Continuous glucose monitoring was used to assess glucose levels in 12 enterally fed patients with diabetes receiving the standard formula followed by the diabetes-specific formula continuously for 5 days each (protocol 2). End points included postprandial glycemia and insulinemia, glycemic variability (mean amplitude of glycemic excursions [MAGE]), mean glucose, and insulin use. In the postprandial response protocol, the diabetes-specific formula resulted in lower positive areas under the postprandial curve (P < 0.001) and peak glucose (P < 0.001) and insulin (P = 0.017) levels. In the protocol using continuous glucose monitoring, glycemic variability (as measured by MAGE) was lower with continuous administration of the diabetes-specific than the standard formula (64.6 +/- 6.8 mg/dL vs. 110.6 +/-15.3 mg/dL, P = 0.003). Also, administration of the diabetes-specific formula resulted in lower mean glucose concentrations during feeding (171.1 +/- 16.1 vs. 202.1 +/- 17.4 mg/dL, P = 0.024) and insulin requirements (7.8 +/- 2.3 vs. 10.9 +/- 3.3 units/day, P = 0.039) than the standard formula. Relative to the standard formula, the diabetes-specific formula reduced postprandial glycemia, mean glucose, glycemic variability, and short-acting insulin requirements. These results suggest potential clinical usefulness of a diabetes-specific enteral formula for minimizing glycemic excursions in hospitalized patients.

Is there a place for extended assessments in addressing child sexual abuse allegations? How sensitivity and specificity impact professional perspectives.

PubMed

Williams, Javonda; Nelson-Gardell, Debra; Coulborn Faller, Kathleen; Tishelman, Amy; Cordisco-Steele, Linda

2014-01-01

Using data from a survey of perceptions of 932 child welfare professionals about the utility of extended assessments, the researchers constructed a scale to measure respondents' views about sensitivity (ensuring sexually abused children are correctly identified) and specificity (ensuring nonabused children are correctly identified) in child sexual abuse evaluations. On average, respondents scored high (valuing sensitivity) on the sensitivity versus specificity scale. Next, the researchers undertook bivariate analyses to identify independent variables significantly associated with the sensitivity versus specificity scale. Then those variables were entered into a multiple regression. Four independent variables were significantly related to higher sensitivity scores: encountering cases requiring extended assessments, valuing extended assessments among scarce resources, less concern about proving cases in court, and viewing the goal of extended assessments as understanding needs of child and family (adjusted R2 = .34).

Mobility assessment: Sensitivity and specificity of measurement sets in older adults

PubMed Central

Panzer, Victoria P.; Wakefield, Dorothy B.; Hall, Charles B.; Wolfson, Leslie I.

2011-01-01

Objective To identify quantitative measurement variables that characterize mobility in older adults, meet reliability and validity criteria, distinguish fall-risk and predict future falls. Design Observational study with 1-year weekly falls follow-up Setting Mobility laboratory Participants Community-dwelling volunteers (n=74; 65–94 years old) categorized at entry as 27 ‘Non-fallers’ or 47 ‘Fallers’ by Medicare criteria (1 injury fall or >1 non-injury falls in the previous year). Interventions None Outcome Measures Test-retest and within-subject reliability, criterion and concurrent validity; predictive ability indicated by observed sensitivity and specificity to entry fall-risk group (Falls-status), Tinetti Performance Oriented Mobility Assessment (POMA), Computerized Dynamic Posturography Sensory Organization Test (SOT) and subsequent falls reported weekly. Results Measurement variables were selected that met reliability (ICC > 0.6) and/or discrimination (p<.01) criteria (Clinical variables- Turn- steps, time, Gait- velocity, Step-in-tub-time, and Downstairs- time; Force plate variables- Quiet standing Romberg ratio sway-area, Maximal lean- anterior-posterior excursion, Sit-to-stand medial-lateral excursion and sway-area). Sets were created (3 clinical, 2 force plate) utilizing combinations of variables appropriate for older adults with different functional activity levels and composite scores were calculated. Scores identified entry Falls-status and concurred with POMA and SOT. The Full clinical set (5 measurement variables) produced sensitivity/specificity (.80/.74) to Falls-status. Composite scores were sensitive and specific in predicting subsequent injury falls and multiple falls compared to Falls-status, POMA or SOT. Conclusions Sets of quantitative measurement variables obtained with this mobility battery provided sensitive prediction of future injury falls and screening for multiple subsequent falls using tasks that should be appropriate to diverse participants. PMID:21621667

Prognostic grouping of metastatic prostate cancer using conventional pretreatment prognostic factors.

PubMed

Mikkola, Arto; Aro, Jussi; Rannikko, Sakari; Ruutu, Mirja

2009-01-01

To develop three prognostic groups for disease specific mortality based on the binary classified pretreatment variables age, haemoglobin concentration (Hb), erythrocyte sedimentation rate (ESR), alkaline phosphatase (ALP), prostate-specific antigen (PSA), plasma testosterone and estradiol level in hormonally treated patients with metastatic prostate cancer (PCa). The present study comprised 200 Finnprostate 6 study patients, but data on all variables were not known for every patient. The patients were divided into three prognostic risk groups (Rgs) using the prognostically best set of pretreatment variables. The best set was found by backward stepwise selection and the effect of every excluded variable on the binary classification cut-off points of the remaining variables was checked and corrected when needed. The best group of variables was ALP, PSA, ESR and age. All data were known in 142 patients. Patients were given one risk point each for ALP > 180 U/l (normal value 60-275 U/l), PSA > 35 microg/l, ESR > 80 mm/h and age < 60 years. Three risk groups were formed: Rg-a (0-1 risk points), Rg-b (2 risk points) and Rg-c (3-4 risk points). The risk of death from PCa increased statistically significantly with advancing prognostic group. Patients with metastatic PCa can be divided into three statistically significantly different prognostic risk groups for PCa-specific mortality by using the binary classified pretreatment variables ALP, PSA, ESR and age.

Predictors of emotional problems and physical aggression among children of Hong Kong Chinese, Mainland Chinese and Filipino immigrants to Canada.

PubMed

Beiser, Morton; Hamilton, Hayley; Rummens, Joanna Anneke; Oxman-Martinez, Jacqueline; Ogilvie, Linda; Humphrey, Chuck; Armstrong, Robert

2010-10-01

Data from the New Canadian Children and Youth Study (NCCYS), a national study of immigrant children and youth in Canada, are used to examine the mental health salience of putatively universal determinants, as well as of immigration-specific factors. Universal factors (UF) include age, gender, family and neighbourhood characteristics. Migration-specific (MS) factors include ethnic background, acculturative stress, prejudice, and the impact of region of resettlement within Canada. In a sample of children from Hong Kong, the Philippines and Mainland China, the study examined the determinants of emotional problems (EP), and physical aggression (PA). A two-step regression analysis entered UF on step 1, and MS variables on step 2. Universal factors accounted for 12.1% of EP variance. Addition of MS variables increased explained variance to 15.6%. Significant UF predictors: parental depression, family dysfunction, and parent's education. Significant MS variables: country of origin, region of resettlement, resettlement stress, prejudice, and limited linguistic fluency. UF accounted for 6.3% of variance in PA scores. Adding migration-specific variables increased variance explained to 9.1%. UF: age, gender, parent's depression, family dysfunction. MS: country of origin, region of resettlement, resettlement stress, and parent's perception of prejudice. Net of the effect of factors affecting the mental health of most, if not all children, migration-specific variables contribute to understanding immigrant children's mental health.

Risk adjustment for comparing hospital quality with surgery: how many variables are needed?

PubMed

Dimick, Justin B; Osborne, Nicholas H; Hall, Bruce L; Ko, Clifford Y; Birkmeyer, John D

2010-04-01

The American College of Surgeons' National Surgical Quality Improvement Program (ACS NSQIP) will soon be reporting procedure-specific outcomes, and hopes to reduce the burden of data collection by collecting fewer variables. We sought to determine whether these changes threaten the robustness of the risk adjustment of hospital quality comparisons. We used prospective, clinical data from the ACS NSQIP from 2005 to 2007 (184 hospitals, 74,887 patients). For the 5 general surgery operations in the procedure-specific NSQIP, we compared the ability of the full model (21 variables), an intermediate model (12 variables), and a limited model (5 variables) to predict patient outcomes and to risk-adjust hospital outcomes. The intermediate and limited models were comparable with the full model in all analyses. In the assessment of patient risk, the limited and full models had very similar discrimination at the patient level (C-indices for all 5 procedures combined of 0.93 versus 0.91 for mortality and 0.78 versus 0.76 for morbidity) and showed good calibration across strata of patient risk. In assessing hospital-specific outcomes, results from the limited and full-risk models were highly correlated for both mortality (range 0.94 to 0.99 across the 5 operations) and morbidity (range 0.96 to 0.99). Procedure-specific hospital quality measures can be adequately risk-adjusted with a limited number of variables. In the context of the ACS NSQIP, moving to a more limited model will dramatically reduce the burden of data collection for participating hospitals. Published by Elsevier Inc.

Microeconomics, Private Security, and the Significance to Operational Planning

DTIC Science & Technology

2013-05-23

of microeconomic principles of supply-demand theory by looking at specific conceptual variables to determine the relationship and influence on the... microeconomic principles of supply-demand theory by looking at specific conceptual variables to determine the relationship and influence on the...study to include existing conceptual understandings of the industry, the microeconomic principles of supply- demand theory, the theoretic framework

The Variables of Composition: Process and Product in a Business Setting. Studies in Writing & Rhetoric Series.

ERIC Educational Resources Information Center

Broadhead, Glenn J.; Freed, Richard C.

Describing the variables of composition, offering researchers a methodology with which to investigate how the variables interact in specific writing strategies, and suggesting how teachers might make use of the variables of revision to help students learn successful writing strategies appropriate to a business setting, this book reports a research…

Morphological, motor and situation-motor characteristics of elite female handball players according to playing performance and position.

PubMed

Cavala, Marijana; Katić, Ratko

2010-12-01

The aim of the study was to define biomotor characteristics that determine playing performance and position in female handball. A battery of 13 variables consisting of somatotype components (3 variables), basic motor abilities (5 variables) and specific motor abilities (5 variables) were applied in a sample of 52 elite female handball players. Differences in biomotor characteristics according to playing performance and position of female handball players were determined by use of the analysis of variance (ANOVA) and discriminative analysis. Study results showed the high-quality female handball players to predominantly differ from the less successful ones in the specific factor of throw strength and basic dash factor, followed by the specific abilities of movement without and with ball, basic coordination/agility and specific ability of ball manipulation, and a more pronounced mesomorphic component. Results also revealed the wing players to be superior in the speed of movement frequency (psychomotor speed), run (explosive strength) and speed of movement with ball as compared with players at other playing positions. Also, endomorphic component was less pronounced in players at the wing and back player positions as compared with goalkeeper and pivot positions, where endomorphic component was considerably more pronounced.

Universal, developmental, and variable aspects of young children's play: a cross-cultural comparison of pretending at home.

PubMed

Haight, W L; Wang, X L; Fung, H H; Williams, K; Mintz, J

1999-01-01

Using longitudinal data from five Irish American families in the United States and nine Chinese families in Taiwan, in conjunction with an emerging body of evidence in the cultural psychology literature, we propose universal, culturally variable, and developmental dimensions of young children's pretend play. Possible universal dimensions include the use of objects, and the predominantly social nature of pretend play. Developmental dimensions include increases in the proportion of social pretend play initiated by the child, the proportion of partner initiations elaborated upon by the child, and caregivers' use of pretend play initiations to serve other, nonplay social functions. Culturally variable dimensions include the centrality of objects, the participation of specific play partners, the extent of child initiations of social pretend play with caregivers, the various functions of social pretend play in interaction, and specific themes. These findings raise the theoretical issue of how universal and variable dimensions of pretend play interact in specific communities to create distinctive development pathways.

A study of variable thrust, variable specific impulse trajectories for solar system exploration

NASA Astrophysics Data System (ADS)

Sakai, Tadashi

A study has been performed to determine the advantages and disadvantages of variable thrust and variable Isp (specific impulse) trajectories for solar system exploration. There have been several numerical research efforts for variable thrust, variable Isp, power-limited trajectory optimization problems. All of these results conclude that variable thrust, variable Isp (variable specific impulse, or VSI) engines are superior to constant thrust, constant Isp (constant specific impulse; or CSI) engines. However, most of these research efforts assume a mission from Earth to Mars, and some of them further assume that these planets are circular and coplanar. Hence they still lack the generality. This research has been conducted to answer the following questions: (1) Is a VSI engine always better than a CSI engine or a high thrust engine for any mission to any planet with any time of flight considering lower propellant mass as the sole criterion? (2) If a planetary swing-by is used for a VSI trajectory, is the fuel savings of a VSI swing-by trajectory better than that of a CSI swing-by or high thrust swing-by trajectory? To support this research, an unique, new computer-based interplanetary trajectory calculation program has been created. This program utilizes a calculus of variations algorithm to perform overall optimization of thrust, Isp, and thrust vector direction along a trajectory that minimizes fuel consumption for interplanetary travel. It is assumed that the propulsion system is power-limited, and thus the compromise between thrust and Isp is a variable to be optimized along the flight path. This program is capable of optimizing not only variable thrust trajectories but also constant thrust trajectories in 3-D space using a planetary ephemeris database. It is also capable of conducting planetary swing-bys. Using this program, various Earth-originating trajectories have been investigated and the optimized results have been compared to traditional CSI and high thrust trajectory solutions. Results show that VSI rocket engines reduce fuel requirements for any mission compared to CSI rocket engines. Fuel can be saved by applying swing-by maneuvers for VSI engines; but the effects of swing-bys due to VSI engines are smaller than that of CSI or high thrust engines.

Intercenter Differences in Bronchopulmonary Dysplasia or Death Among Very Low Birth Weight Infants

PubMed Central

Walsh, Michele; Bobashev, Georgiy; Das, Abhik; Levine, Burton; Carlo, Waldemar A.; Higgins, Rosemary D.

2011-01-01

OBJECTIVES: To determine (1) the magnitude of clustering of bronchopulmonary dysplasia (36 weeks) or death (the outcome) across centers of the Eunice Kennedy Shriver National Institute of Child and Human Development National Research Network, (2) the infant-level variables associated with the outcome and estimate their clustering, and (3) the center-specific practices associated with the differences and build predictive models. METHODS: Data on neonates with a birth weight of <1250 g from the cluster-randomized benchmarking trial were used to determine the magnitude of clustering of the outcome according to alternating logistic regression by using pairwise odds ratio and predictive modeling. Clinical variables associated with the outcome were identified by using multivariate analysis. The magnitude of clustering was then evaluated after correction for infant-level variables. Predictive models were developed by using center-specific and infant-level variables for data from 2001 2004 and projected to 2006. RESULTS: In 2001–2004, clustering of bronchopulmonary dysplasia/death was significant (pairwise odds ratio: 1.3; P < .001) and increased in 2006 (pairwise odds ratio: 1.6; overall incidence: 52%; range across centers: 32%–74%); center rates were relatively stable over time. Variables that varied according to center and were associated with increased risk of outcome included lower body temperature at NICU admission, use of prophylactic indomethacin, specific drug therapy on day 1, and lack of endotracheal intubation. Center differences remained significant even after correction for clustered variables. CONCLUSION: Bronchopulmonary dysplasia/death rates demonstrated moderate clustering according to center. Clinical variables associated with the outcome were also clustered. Center differences after correction of clustered variables indicate presence of as-yet unmeasured center variables. PMID:21149431

Spatial variability of specific surface area of arable soils in Poland

NASA Astrophysics Data System (ADS)

Sokolowski, S.; Sokolowska, Z.; Usowicz, B.

2012-04-01

Evaluation of soil spatial variability is an important issue in agrophysics and in environmental research. Knowledge of spatial variability of physico-chemical properties enables a better understanding of several processes that take place in soils. In particular, it is well known that mineralogical, organic, as well as particle-size compositions of soils vary in a wide range. Specific surface area of soils is one of the most significant characteristics of soils. It can be not only related to the type of soil, mainly to the content of clay, but also largely determines several physical and chemical properties of soils and is often used as a controlling factor in numerous biological processes. Knowledge of the specific surface area is necessary in calculating certain basic soil characteristics, such as the dielectric permeability of soil, water retention curve, water transport in the soil, cation exchange capacity and pesticide adsorption. The aim of the present study is two-fold. First, we carry out recognition of soil total specific surface area patterns in the territory of Poland and perform the investigation of features of its spatial variability. Next, semivariograms and fractal analysis are used to characterize and compare the spatial variability of soil specific surface area in two soil horizons (A and B). Specific surface area of about 1000 samples was determined by analyzing water vapor adsorption isotherms via the BET method. The collected data of the values of specific surface area of mineral soil representatives for the territory of Poland were then used to describe its spatial variability by employing geostatistical techniques and fractal theory. Using the data calculated for some selected points within the entire territory and along selected directions, the values of semivariance were determined. The slope of the regression line of the log-log plot of semi-variance versus the distance was used to estimate the fractal dimension, D. Specific surface area in A and B horizons was space-dependent, with the range of spatial dependence of about 2.5°. Variogram surfaces showed anisotropy of the specific surface area in both horizons with a trend toward the W to E directions. The smallest fractal dimensions were obtained for W to E directions and the highest values - for S to N directions. * The work was financially supported in part by the ESA Programme for European Cooperating States (PECS), No.98084 "SWEX-R, Soil Water and Energy Exchange/Research", AO3275.

Using Instrumental Variable (IV) Tests to Evaluate Model Specification in Latent Variable Structural Equation Models*

PubMed Central

Kirby, James B.; Bollen, Kenneth A.

2009-01-01

Structural Equation Modeling with latent variables (SEM) is a powerful tool for social and behavioral scientists, combining many of the strengths of psychometrics and econometrics into a single framework. The most common estimator for SEM is the full-information maximum likelihood estimator (ML), but there is continuing interest in limited information estimators because of their distributional robustness and their greater resistance to structural specification errors. However, the literature discussing model fit for limited information estimators for latent variable models is sparse compared to that for full information estimators. We address this shortcoming by providing several specification tests based on the 2SLS estimator for latent variable structural equation models developed by Bollen (1996). We explain how these tests can be used to not only identify a misspecified model, but to help diagnose the source of misspecification within a model. We present and discuss results from a Monte Carlo experiment designed to evaluate the finite sample properties of these tests. Our findings suggest that the 2SLS tests successfully identify most misspecified models, even those with modest misspecification, and that they provide researchers with information that can help diagnose the source of misspecification. PMID:20419054

Surgical Risk Preoperative Assessment System (SURPAS): II. Parsimonious Risk Models for Postoperative Adverse Outcomes Addressing Need for Laboratory Variables and Surgeon Specialty-specific Models.

PubMed

Meguid, Robert A; Bronsert, Michael R; Juarez-Colunga, Elizabeth; Hammermeister, Karl E; Henderson, William G

2016-07-01

To develop parsimonious prediction models for postoperative mortality, overall morbidity, and 6 complication clusters applicable to a broad range of surgical operations in adult patients. Quantitative risk assessment tools are not routinely used for preoperative patient assessment, shared decision making, informed consent, and preoperative patient optimization, likely due in part to the burden of data collection and the complexity of incorporation into routine surgical practice. Multivariable forward selection stepwise logistic regression analyses were used to develop predictive models for 30-day mortality, overall morbidity, and 6 postoperative complication clusters, using 40 preoperative variables from 2,275,240 surgical cases in the American College of Surgeons National Surgical Quality Improvement Program data set, 2005 to 2012. For the mortality and overall morbidity outcomes, prediction models were compared with and without preoperative laboratory variables, and generic models (based on all of the data from 9 surgical specialties) were compared with specialty-specific models. In each model, the cumulative c-index was used to examine the contribution of each added predictor variable. C-indexes, Hosmer-Lemeshow analyses, and Brier scores were used to compare discrimination and calibration between models. For the mortality and overall morbidity outcomes, the prediction models without the preoperative laboratory variables performed as well as the models with the laboratory variables, and the generic models performed as well as the specialty-specific models. The c-indexes were 0.938 for mortality, 0.810 for overall morbidity, and for the 6 complication clusters ranged from 0.757 for infectious to 0.897 for pulmonary complications. Across the 8 prediction models, the first 7 to 11 variables entered accounted for at least 99% of the c-index of the full model (using up to 28 nonlaboratory predictor variables). Our results suggest that it will be possible to develop parsimonious models to predict 8 important postoperative outcomes for a broad surgical population, without the need for surgeon specialty-specific models or inclusion of laboratory variables.

A general theoretical framework for interpreting patient-reported outcomes estimated from ordinally scaled item responses.

PubMed

Massof, Robert W

2014-10-01

A simple theoretical framework explains patient responses to items in rating scale questionnaires. Fixed latent variables position each patient and each item on the same linear scale. Item responses are governed by a set of fixed category thresholds, one for each ordinal response category. A patient's item responses are magnitude estimates of the difference between the patient variable and the patient's estimate of the item variable, relative to his/her personally defined response category thresholds. Differences between patients in their personal estimates of the item variable and in their personal choices of category thresholds are represented by random variables added to the corresponding fixed variables. Effects of intervention correspond to changes in the patient variable, the patient's response bias, and/or latent item variables for a subset of items. Intervention effects on patients' item responses were simulated by assuming the random variables are normally distributed with a constant scalar covariance matrix. Rasch analysis was used to estimate latent variables from the simulated responses. The simulations demonstrate that changes in the patient variable and changes in response bias produce indistinguishable effects on item responses and manifest as changes only in the estimated patient variable. Changes in a subset of item variables manifest as intervention-specific differential item functioning and as changes in the estimated person variable that equals the average of changes in the item variables. Simulations demonstrate that intervention-specific differential item functioning produces inefficiencies and inaccuracies in computer adaptive testing. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Moderation and Mediation in Structural Equation Modeling: Applications for Early Intervention Research

ERIC Educational Resources Information Center

Hopwood, Christopher J.

2007-01-01

Second-generation early intervention research typically involves the specification of multivariate relations between interventions, outcomes, and other variables. Moderation and mediation involve variables or sets of variables that influence relations between interventions and outcomes. Following the framework of Baron and Kenny's (1986) seminal…

Measurement Model Specification Error in LISREL Structural Equation Models.

ERIC Educational Resources Information Center

Baldwin, Beatrice; Lomax, Richard

This LISREL study examines the robustness of the maximum likelihood estimates under varying degrees of measurement model misspecification. A true model containing five latent variables (two endogenous and three exogenous) and two indicator variables per latent variable was used. Measurement model misspecification considered included errors of…

Reinforcement and Induction of Operant Variability

ERIC Educational Resources Information Center

Neuringer, Allen

2012-01-01

The target paper by Barba (2012) raises issues that were the focus of the author's first two publications on operant variability. The author will describe the main findings in those papers and then discuss Barba's specific arguments. Barba has argued against the operant nature of variability. (Contains 2 figures.)

The Variability of Gender-Based Communication in Japanese Magazine Advertising.

ERIC Educational Resources Information Center

Maynard, Michael L.

1995-01-01

Analyzes Japanese magazine advertising text from an intracultural perspective based on gender. Uses content analysis to examine advertising text of eight gender-specific magazines. Reveals significant difference in the variability of message perception depending on target gender. Suggests the importance of recognizing intracultural variability,…

Spatial Topography of Individual-Specific Cortical Networks Predicts Human Cognition, Personality, and Emotion.

PubMed

Kong, Ru; Li, Jingwei; Orban, Csaba; Sabuncu, Mert R; Liu, Hesheng; Schaefer, Alexander; Sun, Nanbo; Zuo, Xi-Nian; Holmes, Avram J; Eickhoff, Simon B; Yeo, B T Thomas

2018-06-06

Resting-state functional magnetic resonance imaging (rs-fMRI) offers the opportunity to delineate individual-specific brain networks. A major question is whether individual-specific network topography (i.e., location and spatial arrangement) is behaviorally relevant. Here, we propose a multi-session hierarchical Bayesian model (MS-HBM) for estimating individual-specific cortical networks and investigate whether individual-specific network topography can predict human behavior. The multiple layers of the MS-HBM explicitly differentiate intra-subject (within-subject) from inter-subject (between-subject) network variability. By ignoring intra-subject variability, previous network mappings might confuse intra-subject variability for inter-subject differences. Compared with other approaches, MS-HBM parcellations generalized better to new rs-fMRI and task-fMRI data from the same subjects. More specifically, MS-HBM parcellations estimated from a single rs-fMRI session (10 min) showed comparable generalizability as parcellations estimated by 2 state-of-the-art methods using 5 sessions (50 min). We also showed that behavioral phenotypes across cognition, personality, and emotion could be predicted by individual-specific network topography with modest accuracy, comparable to previous reports predicting phenotypes based on connectivity strength. Network topography estimated by MS-HBM was more effective for behavioral prediction than network size, as well as network topography estimated by other parcellation approaches. Thus, similar to connectivity strength, individual-specific network topography might also serve as a fingerprint of human behavior.

Asthma-specific cognitions, self-focused attention, and fear of negative evaluation in adolescents and young adults diagnosed with childhood-onset asthma.

PubMed

Junghans-Rutelonis, Ashley N; Tackett, Alayna P; Suorsa, Kristina I; Chaney, John M; Mullins, Larry L

2018-01-01

The present study examined the impact of asthma-specific thought intrusion (TI) and thought suppression (TS) on two cognitive-affective variables (self-focused attention and fear of negative evaluation) among adolescents and young adults (AYAs) diagnosed with childhood-onset asthma. Participants were 290 AYAs who completed assessment questionnaires and participated in a written exercise electronically. Asthma-TI and TS were reported by participants following participation in a writing assignment. Asthma-TI was associated with increased private, public, and social anxiety self-focused attention, and greater fear of negative evaluation. Interestingly, asthma-TS was not associated with these same outcome variables. Findings suggest illness-specific cognitions are associated with cognitive-affective variables and it may be important to assess for illness-specific intrusive thoughts following asthma-focused medical appointments. Additionally, findings suggest the importance of assessing asthma-TI and TS separately in order to better understand thoughts about health and psychological functioning.

Specification of the ISS Plasma Environment Variability

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Neergaard, Linda F.; Bui, Them H.; Mikatarian, Ronald R.; Barsamian, H.; Koontz, Steven L.

2002-01-01

Quantifying the spacecraft charging risks and corresponding hazards for the International Space Station (ISS) requires a plasma environment specification describing the natural variability of ionospheric temperature (Te) and density (Ne). Empirical ionospheric specification and forecast models such as the International Reference Ionosphere (IRI) model typically only provide estimates of long term (seasonal) mean Te and Ne values for the low Earth orbit environment. Knowledge of the Te and Ne variability as well as the likelihood of extreme deviations from the mean values are required to estimate both the magnitude and frequency of occurrence of potentially hazardous spacecraft charging environments for a given ISS construction stage and flight configuration. This paper describes the statistical analysis of historical ionospheric low Earth orbit plasma measurements used to estimate Ne, Te variability in the ISS flight environment. The statistical variability analysis of Ne and Te enables calculation of the expected frequency of Occurrence of any particular values of Ne and Te, especially those that correspond to possibly hazardous spacecraft charging environments. The database used in the original analysis included measurements from the AE-C, AE-D, and DE-2 satellites. Recent work on the database has added additional satellites to the database and ground based incoherent scatter radar observations as well. Deviations of the data values from the IRI estimated Ne, Te parameters for each data point provide a statistical basis for modeling the deviations of the plasma environment from the IRI model output. This technique, while developed specifically for the Space Station analysis, can also be generalized to provide ionospheric plasma environment risk specification models for low Earth orbit over an altitude range of 200 km through approximately 1000 km.

Intra- and interspecific trait variations reveal functional relationships between specific leaf area and soil niche within a subtropical forest.

PubMed

He, Dong; Chen, Yongfa; Zhao, Kangning; Cornelissen, J H C; Chu, Chengjin

2018-02-03

How functional traits vary with environmental conditions is of fundamental importance in trait-based community ecology. However, how intraspecific variability in functional traits is connected to species distribution is not well understood. This study investigated inter- and intraspecific variation of a key functional trait, i.e. specific leaf area (leaf area per unit dry mass; SLA), in relation to soil factors and tested if trait variation is more closely associated with specific environmental regimes for low-variability species than for high-variability species. In a subtropical evergreen forest plot (50 ha, southern China), 106 700 leaves from 5335 individuals of 207 woody species were intensively collected, with 30 individuals sampled for most species to ensure a sufficient sample size representative of intraspecific variability. Soil conditions for each plant were estimated by kriging from more than 1700 observational soil locations across the plot. Intra- and interspecific variation in SLA were separately related to environmental factors. Based on the species-specific variation of SLA, species were categorized into three groups: low-, intermediate- and high-intraspecific variability. Intraspecific habitat ranges and the strength of SLA-habitat relationships were compared among these three groups. Interspecific variation in SLA overrides the intraspecific variation (77 % vs. 8 %). Total soil nitrogen (TN, positively) and total organic carbon (TOC, negatively) are the most important explanatory factors for SLA variation at both intra- and interspecific levels. SLA, both within and between species, decreases with decreasing soil nitrogen availability. As predicted, species with low intraspecific variability in SLA have narrower habitat ranges with respect to soil TOC and TN and show a stronger SLA-habitat association than high-variability species. For woody plants low SLA is a phenotypic and probably adaptive response to nitrogen stress, which drives the predominance of species with ever-decreasing SLA towards less fertile habitats. Intraspecific variability in SLA is positively connected to species' niche breadth, suggesting that low-variability species may play a more deterministic role in structuring plant assemblages than high-variability species. This study highlights the importance of quantifying intraspecific trait variation to improve our understanding of species distributions across a vegetated landscape. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The Relationship between Brand-Specific Alcohol Advertising on Television and Brand-Specific Consumption among Underage Youth

PubMed Central

Ross, Craig S.; Maple, Emily; Siegel, Michael; DeJong, William; Naimi, Timothy S.; Ostroff, Joshua; Padon, Alisa A.; Borzekowski, Dina L.G.; Jernigan, David H.

2014-01-01

Background Being able to investigate the relationship between underage drinkers' preferences for particular brands and their exposure to advertising for those brands would represent a significant advance in alcohol marketing research. However, no previous national study has examined the relationship between underage youth exposure to brand-specific alcohol advertising and consumption of those brands. Methods We conducted a cross-sectional, internet-based survey of a national sample of 1,031 youths, ages 13-20, who had consumed at least one drink of alcohol in the past 30 days. We ascertained all alcohol brands consumed by respondents in the past 30 days. The main outcome measure was brand-specific consumption during the past 30 days, measured as a dichotomous variable. The main predictor variable was exposure to brand-specific alcohol advertising on television. The respondents reported which of 20 television shows popular with youth they had watched during the past 30 days. For each respondent, we calculated a standard measure of potential exposure to the brand-specific alcohol advertising that aired on those shows during the preceding 12 months, based on Nielsen (New York, NY) estimates of the youth audience for each show's telecasts. Results Compared to no brand-specific advertising exposure, any exposure was associated with an increased likelihood of brand-specific consumption (adjusted odds ratio 3.02; 95% confidence interval: 2.61-3.49) after controlling for several individual- and brand-level variables. When measured as a continuous variable, the relationship between advertising exposure and brand consumption was nonlinear, with a large association at lower levels of exposure and diminishing incremental effects as the level of exposure increased. Conclusions There is a robust relationship between youth's brand-specific exposure to alcohol advertising on television and their consumption of those same alcohol brands during the past 30 days. This study provides further evidence of a strong association between alcohol advertising and youth drinking behavior. PMID:24986257

The relationship between brand-specific alcohol advertising on television and brand-specific consumption among underage youth.

PubMed

Ross, Craig S; Maple, Emily; Siegel, Michael; DeJong, William; Naimi, Timothy S; Ostroff, Joshua; Padon, Alisa A; Borzekowski, Dina L G; Jernigan, David H

2014-08-01

Being able to investigate the relationship between underage drinkers' preferences for particular brands and their exposure to advertising for those brands would represent a significant advance in alcohol marketing research. However, no previous national study has examined the relationship between underage youth exposure to brand-specific alcohol advertising and consumption of those brands. We conducted a cross-sectional, Internet-based survey of a national sample of 1,031 youth, ages 13-20, who had consumed at least 1 drink of alcohol in the past 30 days. We ascertained all alcohol brands consumed by respondents in the past 30 days. The main outcome measure was brand-specific consumption during the past 30 days, measured as a dichotomous variable. The main predictor variable was exposure to brand-specific alcohol advertising on television. The respondents reported which of 20 television shows popular with youth they had watched during the past 30 days. For each respondent, we calculated a standard measure of potential exposure to the brand-specific alcohol advertising that aired on those shows during the preceding 12 months, based on Nielsen (New York, NY) estimates of the youth audience for each show's telecasts. Compared to no brand-specific advertising exposure, any exposure was associated with an increased likelihood of brand-specific consumption (adjusted odds ratio 3.02; 95% confidence interval: 2.61-3.49) after controlling for several individual- and brand-level variables. When measured as a continuous variable, the relationship between advertising exposure and brand consumption was nonlinear, with a large association at lower levels of exposure and diminishing incremental effects as the level of exposure increased. There is a robust relationship between youth's brand-specific exposure to alcohol advertising on television and their consumption of those same alcohol brands during the past 30 days. This study provides further evidence of a strong association between alcohol advertising and youth drinking behavior. Copyright © 2014 by the Research Society on Alcoholism.

13 CFR 120.214 - What conditions apply for variable interest rates?

Code of Federal Regulations, 2010 CFR

2010-01-01

... interest rates? 120.214 Section 120.214 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Policies Specific to 7(a) Loans Maturities; Interest Rates; Loan and Guarantee Amounts § 120.214 What conditions apply for variable interest rates? A Lender may use a variable rate of interest...

Much Ado about Nothing--Or at Best, Very Little

ERIC Educational Resources Information Center

Widaman, Keith F.

2014-01-01

Latent variable structural equation modeling has become the analytic method of choice in many domains of research in psychology and allied social sciences. One important aspect of a latent variable model concerns the relations hypothesized to hold between latent variables and their indicators. The most common specification of structural equation…

Five-Factor Model of Personality and Career Exploration

ERIC Educational Resources Information Center

Reed, Mary Beth; Bruch, Monroe A.; Haase, Richard F.

2004-01-01

This study investigates whether the dimensions of the five-factor model (FFM) of personality are related to specific career exploration variables. Based on the FFM, predictions were made about the relevance of particular traits to career exploration variables. Results from a canonical correlation analysis showed that variable loadings on three…

A Composite Likelihood Inference in Latent Variable Models for Ordinal Longitudinal Responses

ERIC Educational Resources Information Center

Vasdekis, Vassilis G. S.; Cagnone, Silvia; Moustaki, Irini

2012-01-01

The paper proposes a composite likelihood estimation approach that uses bivariate instead of multivariate marginal probabilities for ordinal longitudinal responses using a latent variable model. The model considers time-dependent latent variables and item-specific random effects to be accountable for the interdependencies of the multivariate…

Demographic and Indication-Specific Characteristics Have Limited Association With Social Network Engagement: Evidence From 24,954 Members of Four Health Care Support Groups

PubMed Central

2017-01-01

Background Digital health social networks (DHSNs) are widespread, and the consensus is that they contribute to wellness by offering social support and knowledge sharing. The success of a DHSN is based on the number of participants and their consistent creation of externalities through the generation of new content. To promote network growth, it would be helpful to identify characteristics of superusers or actors who create value by generating positive network externalities. Objective The aim of the study was to investigate the feasibility of developing predictive models that identify potential superusers in real time. This study examined associations between posting behavior, 4 demographic variables, and 20 indication-specific variables. Methods Data were extracted from the custom structured query language (SQL) databases of 4 digital health behavior change interventions with DHSNs. Of these, 2 were designed to assist in the treatment of addictions (problem drinking and smoking cessation), and 2 for mental health (depressive disorder, panic disorder). To analyze posting behavior, 10 models were developed, and negative binomial regressions were conducted to examine associations between number of posts, and demographic and indication-specific variables. Results The DHSNs varied in number of days active (3658-5210), number of registrants (5049-52,396), number of actors (1085-8452), and number of posts (16,231-521,997). In the sample, all 10 models had low R2 values (.013-.086) with limited statistically significant demographic and indication-specific variables. Conclusions Very few variables were associated with social network engagement. Although some variables were statistically significant, they did not appear to be practically significant. Based on the large number of study participants, variation in DHSN theme, and extensive time-period, we did not find strong evidence that demographic characteristics or indication severity sufficiently explain the variability in number of posts per actor. Researchers should investigate alternative models that identify superusers or other individuals who create social network externalities. PMID:28213340

Interobserver variability of sonography for prediction of placenta accreta.

PubMed

Bowman, Zachary S; Eller, Alexandra G; Kennedy, Anne M; Richards, Douglas S; Winter, Thomas C; Woodward, Paula J; Silver, Robert M

2014-12-01

The sensitivity of sonography to predict accreta has been reported as higher than 90%. However, most studies are from single expert investigators. Our objective was to analyze interobserver variability of sonography for prediction of placenta accreta. Patients with previa with and without accreta were ascertained, and images with placental views were collected, deidentified, and placed in random sequence. Three radiologists and 3 maternal-fetal medicine specialists interpreted each study for the presence of accreta and specific findings reported to be associated with its diagnosis. Investigator-specific sensitivity, specificity, and accuracy were calculated. κ statistics were used to assess variability between individuals and types of investigators. A total of 229 sonographic studies from 55 patients with accreta and 56 control patients were examined. Accuracy ranged from 55.9% to 76.4%. Of imaging studies yielding diagnoses, sensitivity ranged from 53.4% to 74.4%, and specificity ranged from 70.8% to 94.8%. Overall interobserver agreement was moderate (mean κ ± SD = 0.47 ± 0.12). κ values between pairs of investigators ranged from 0.32 (fair agreement) to 0.73 (substantial agreement). Average individual agreement ranged from fair (κ = 0.35) to moderate (κ = 0.53). Blinded from clinical data, sonography has significant interobserver variability for the diagnosis of placenta accreta. © 2013 by the American Institute of Ultrasound in Medicine.

Is continence status associated with quality of life in young children with spina bifida?

PubMed

Freeman, Kurt A; Smith, Kathryn; Adams, Elizabeth; Mizokawa, Stacey; Neville-Jan, Ann

2013-01-01

To evaluate the relationship between child- and parent-reported quality of life (QOL) and bowel and bladder continence among young children with spina bifida (SB). 104 children ages 5-12 years and one of their parents/guardians completed the Pediatric Quality of Life Inventory - Generic Form (PedsQL; parent and child) and the Quality of Life in Spina Bifida Questionnaire (QOLSBQ, parent only). Data on continence, child age, and condition-specific variables were obtained by chart review. Parent and child QOL scores (on all measures of QOL) were positively correlated; parents rated child QOL lower than children's self report. QOL scores did not differ based on continence status. Total PedsQL scores were associated with age and mobility based on child report and with mobility based on parent report. QOL may not be affected by continence status among young children with SB, though demographic (i.e., age) and condition-specific (i.e., functional mobility status) variables appear relevant. Additional research is needed to further evaluate condition-specific variables, other protective variables, and possible measurement issues that influence QOL in young children with SB.

The protection motivation theory within the stages of the transtheoretical model - stage-specific interplay of variables and prediction of exercise stage transitions.

PubMed

Lippke, Sonia; Plotnikoff, Ronald C

2009-05-01

Two different theories of health behaviour have been chosen with the aim of theory integration: a continuous theory (protection motivation theory, PMT) and a stage model (transtheoretical model, TTM). This is the first study to test whether the stages of the TTM moderate the interrelation of PMT-variables and the mediation of motivation, as well as PMT-variables' interactions in predicting stage transitions. Hypotheses were tested regarding (1) mean patterns, stage pair-comparisons and nonlinear trends using ANOVAs; (2) prediction-patterns for the different stage groups employing multi-group structural equation modelling (MSEM) and nested model analyses; and (3) stage transitions using binary logistic regression analyses. Adults (N=1,602) were assessed over a 6 month period on their physical activity stages, PMT-variables and subsequent behaviour. (1) Particular mean differences and nonlinear trends in all test variables were found. (2) The PMT adequately fitted the five stage groups. The MSEM revealed that covariances within threat appraisal and coping appraisal were invariant and all other constrains were stage-specific, i.e. stage was a moderator. Except for self-efficacy, motivation fully mediated the relationship between the social-cognitive variables and behaviour. (3) Predicting stage transitions with the PMT-variables underscored the importance of self-efficacy. Only when threat appraisal and coping appraisal were high, stage movement was more likely in the preparation stage. Results emphasize stage-specific differences of the PMT mechanisms, and hence, support the stage construct. The findings may guide further theory building and research integrating different theoretical approaches.

Modelling and Simulation of the Dynamics of the Antigen-Specific T Cell Response Using Variable Structure Control Theory.

PubMed

Anelone, Anet J N; Spurgeon, Sarah K

2016-01-01

Experimental and mathematical studies in immunology have revealed that the dynamics of the programmed T cell response to vigorous infection can be conveniently modelled using a sigmoidal or a discontinuous immune response function. This paper hypothesizes strong synergies between this existing work and the dynamical behaviour of engineering systems with a variable structure control (VSC) law. These findings motivate the interpretation of the immune system as a variable structure control system. It is shown that dynamical properties as well as conditions to analytically assess the transition from health to disease can be developed for the specific T cell response from the theory of variable structure control. In particular, it is shown that the robustness properties of the specific T cell response as observed in experiments can be explained analytically using a VSC perspective. Further, the predictive capacity of the VSC framework to determine the T cell help required to overcome chronic Lymphocytic Choriomeningitis Virus (LCMV) infection is demonstrated. The findings demonstrate that studying the immune system using variable structure control theory provides a new framework for evaluating immunological dynamics and experimental observations. A modelling and simulation tool results with predictive capacity to determine how to modify the immune response to achieve healthy outcomes which may have application in drug development and vaccine design.

Detection of specific antibody responses to vaccination in variable flying foxes (Pteropus hypomelanus).

PubMed

Wellehan, James F X; Green, Linda G; Duke, Diane G; Bootorabi, Shadi; Heard, Darryl J; Klein, Paul A; Jacobson, Elliott R

2009-09-01

Megachiropteran bats are biologically important both as endangered species and reservoirs for emerging human pathogens. Reliable detection of antibodies to specific pathogens in bats is thus epidemiologically critical. Eight variable flying foxes (Pteropus hypomelanus) were immunized with 2,4-dinitrophenylated bovine serum albumin (DNP-BSA). Each bat received monthly inoculations for 2 months. Affinity-purified IgG was used for production of polyclonal and monoclonal anti-variable flying fox IgG antibodies. ELISA and western blot analysis were used to monitor immune responses and for assessment of polyclonal and monoclonal antibody species cross-reactivity. Protein G, polyclonal antibodies, and monoclonal antibodies detected specific anti-DNP antibody responses in immunized variable flying foxes, with protein G being the most sensitive, followed by monoclonal antibodies and then polyclonal antibodies. While the polyclonal antibody was found to cross-react well against IgG of all bat species tested, some non-specific background was observed. The monoclonal antibody was found to cross-react well against IgG of six other species in the genus Pteropus and to cross-react less strongly against IgG from Eidolon helvum or Phyllostomus hastatus. Protein G distinguished best between vaccinated and unvaccinated bats, and these results validate the use of protein G for detection of bat IgG. Monoclonal antibodies developed in this study recognized immunoglobulins from other members of the genus Pteropus well, and may be useful in applications where specific detection of Pteropus IgG is needed.

The specification of a hospital cost function. A comment on the recent literature.

PubMed

Breyer, F

1987-06-01

In the empirical estimation of hospital cost functions, two radically different types of specifications have been chosen to date, ad-hoc forms and flexible functional forms based on neoclassical production theory. This paper discusses the respective strengths and weaknesses of both approaches and emphasizes the apparently unreconcilable conflict between the goals of maintaining functional flexibility and keeping the number of variables manageable if at the same time patient heterogeneity is to be adequately reflected in the case mix variables. A new specification is proposed which strikes a compromise between these goals, and the underlying assumptions are discussed critically.

Relations between basic and specific motor abilities and player quality of young basketball players.

PubMed

Marić, Kristijan; Katić, Ratko; Jelicić, Mario

2013-05-01

Subjects from 5 first league clubs from Herzegovina were tested with the purpose of determining the relations of basic and specific motor abilities, as well as the effect of specific abilities on player efficiency in young basketball players (cadets). A battery of 12 tests assessing basic motor abilities and 5 specific tests assessing basketball efficiency were used on a sample of 83 basketball players. Two significant canonical correlations, i.e. linear combinations explained the relation between the set of twelve variables of basic motor space and five variables of situational motor abilities. Underlying the first canonical linear combination is the positive effect of the general motor factor, predominantly defined by jumping explosive power, movement speed of the arms, static strength of the arms and coordination, on specific basketball abilities: movement efficiency, the power of the overarm throw, shooting and passing precision, and the skill of handling the ball. The impact of basic motor abilities of precision and balance on specific abilities of passing and shooting precision and ball handling is underlying the second linear combination. The results of regression correlation analysis between the variable set of specific motor abilities and game efficiency have shown that the ability of ball handling has the largest impact on player quality in basketball cadets, followed by shooting precision and passing precision, and the power of the overarm throw.

Relative efficiency of joint-model and full-conditional-specification multiple imputation when conditional models are compatible: The general location model.

PubMed

Seaman, Shaun R; Hughes, Rachael A

2018-06-01

Estimating the parameters of a regression model of interest is complicated by missing data on the variables in that model. Multiple imputation is commonly used to handle these missing data. Joint model multiple imputation and full-conditional specification multiple imputation are known to yield imputed data with the same asymptotic distribution when the conditional models of full-conditional specification are compatible with that joint model. We show that this asymptotic equivalence of imputation distributions does not imply that joint model multiple imputation and full-conditional specification multiple imputation will also yield asymptotically equally efficient inference about the parameters of the model of interest, nor that they will be equally robust to misspecification of the joint model. When the conditional models used by full-conditional specification multiple imputation are linear, logistic and multinomial regressions, these are compatible with a restricted general location joint model. We show that multiple imputation using the restricted general location joint model can be substantially more asymptotically efficient than full-conditional specification multiple imputation, but this typically requires very strong associations between variables. When associations are weaker, the efficiency gain is small. Moreover, full-conditional specification multiple imputation is shown to be potentially much more robust than joint model multiple imputation using the restricted general location model to mispecification of that model when there is substantial missingness in the outcome variable.

Predictors of Coping in Divorced Single Mothers.

ERIC Educational Resources Information Center

Propst, L. Rebecca; And Others

1986-01-01

Examined the effects of demographic variables, variables specific to marriage and divorce, and coping resources (internal and external) on the adjustment of single mothers. Results indicate that four classes of variables have an effect on the mother's adjustment: phase of divorce and/or separation; numbers and ages of children; style of coping;…

Variables Influencing Teacher Autonomy, Administrative Coordination, and Collaboration

ERIC Educational Resources Information Center

Prichard, Caleb; Moore, Jana E.

2016-01-01

Purpose: Schools often vary in how they balance teacher autonomy (TA) and administrative control, and research suggests that there may be several context-specific variables which may be influential. The purpose of this paper is to determine the influence of program variables on the level of TA, administrative coordination, and administration-staff…

Personality and Demographic Variables Related to Career Development and Career Concerns.

ERIC Educational Resources Information Center

Ralph, Joan; And Others

Following a literature search of the theories of personal maturation and career development, a study was conducted to identify personality and demographic variables related to career development and career concerns. Specifically investigated was the relationship between two sets of variables with self-concept, locus of control, and age in one set…

Sex estimation based on tooth measurements using panoramic radiographs.

PubMed

Capitaneanu, Cezar; Willems, Guy; Jacobs, Reinhilde; Fieuws, Steffen; Thevissen, Patrick

2017-05-01

Sex determination is an important step in establishing the biological profile of unidentified human remains. The aims of the study were, firstly, to assess the degree of sexual dimorphism in permanent teeth, based on digital tooth measurements performed on panoramic radiographs. Secondly, to identify sex-related tooth position-specific measurements or combinations of such measurements, and to assess their applicability for potential sex determination. Two hundred digital panoramic radiographs (100 males, 100 females; age range 22-34 years) were retrospectively collected from the dental clinic files of the Dentomaxillofacial Radiology Center of the University Hospitals Leuven, Belgium, and imported in image enhancement software. Tooth length- and width-related variables were measured on all teeth in upper and lower left quadrant, and ratios of variables were calculated. Univariate and multivariate analyses were performed to quantify the sex discriminative value of the tooth position-specific variables and their combinations. The mandibular and maxillary canine showed the greatest sexual dimorphism, and tooth length variables had the highest discriminative potential. Compared to single variables, combining variables or ratios of variables did not improve substantially the discrimination between males and females. Considering that the discriminative ability values (area under the curve (AUC)) were not higher than 0.80, it is not advocated to use the currently studied dental variables for accurate sex estimation in forensic practice.

What weather variables are important in predicting heat-related mortality? A new application of statistical learning methods

PubMed Central

Zhang, Kai; Li, Yun; Schwartz, Joel D.; O'Neill, Marie S.

2014-01-01

Hot weather increases risk of mortality. Previous studies used different sets of weather variables to characterize heat stress, resulting in variation in heat-mortality- associations depending on the metric used. We employed a statistical learning method – random forests – to examine which of various weather variables had the greatest impact on heat-related mortality. We compiled a summertime daily weather and mortality counts dataset from four U.S. cities (Chicago, IL; Detroit, MI; Philadelphia, PA; and Phoenix, AZ) from 1998 to 2006. A variety of weather variables were ranked in predicting deviation from typical daily all-cause and cause-specific death counts. Ranks of weather variables varied with city and health outcome. Apparent temperature appeared to be the most important predictor of heat-related mortality for all-cause mortality. Absolute humidity was, on average, most frequently selected one of the top variables for all-cause mortality and seven cause-specific mortality categories. Our analysis affirms that apparent temperature is a reasonable variable for activating heat alerts and warnings, which are commonly based on predictions of total mortality in next few days. Additionally, absolute humidity should be included in future heat-health studies. Finally, random forests can be used to guide choice of weather variables in heat epidemiology studies. PMID:24834832

Variability in Costs across Hospital Wards. A Study of Chinese Hospitals

PubMed Central

Adam, Taghreed; Evans, David B.; Ying, Bian; Murray, Christopher J. L.

2014-01-01

Introduction Analysts estimating the costs or cost-effectiveness of health interventions requiring hospitalization often cut corners because they lack data and the costs of undertaking full step-down costing studies are high. They sometimes use the costs taken from a single hospital, sometimes use simple rules of thumb for allocating total hospital costs between general inpatient care and the outpatient department, and sometimes use the average cost of an inpatient bed-day instead of a ward-specific cost. Purpose In this paper we explore for the first time the extent and the causes of variation in ward-specific costs across hospitals, using data from China. We then use the resulting model to show how ward-specific costs for hospitals outside the data set could be estimated using information on the determinants identified in the paper. Methodology Ward-specific costs estimated using step-down costing methods from 41 hospitals in 12 provinces of China were used. We used seemingly unrelated regressions to identify the determinants of variability in the ratio of the costs of specific wards to that of the outpatient department, and explain how this can be used to generate ward-specific unit costs. Findings Ward-specific unit costs varied considerably across hospitals, ranging from 1 to 24 times the unit cost in the outpatient department — average unit costs are not a good proxy for costs at specialty wards in general. The most important sources of variability were the number of staff and the level of capacity utilization. Practice Implications More careful hospital costing studies are clearly needed. In the meantime, we have shown that in China it is possible to estimate ward-specific unit costs taking into account key determinants of variability in costs across wards. This might well be a better alternative than using simple rules of thumb or using estimates from a single study. PMID:24874566

Geography and the costs of urban energy infrastructure: The case of electricity and natural gas capital investments

NASA Astrophysics Data System (ADS)

Senyel, Muzeyyen Anil

Investments in the urban energy infrastructure for distributing electricity and natural gas are analyzed using (1) property data measuring distribution plant value at the local/tax district level, and (2) system outputs such as sectoral numbers of customers and energy sales, input prices, company-specific characteristics such as average wages and load factor. Socio-economic and site-specific urban and geographic variables, however, often been neglected in past studies. The purpose of this research is to incorporate these site-specific characteristics of electricity and natural gas distribution into investment cost model estimations. These local characteristics include (1) socio-economic variables, such as income and wealth; (2) urban-related variables, such as density, land-use, street pattern, housing pattern; (3) geographic and environmental variables, such as soil, topography, and weather, and (4) company-specific characteristics such as average wages, and load factor. The classical output variables include residential and commercial-industrial customers and sales. In contrast to most previous research, only capital investments at the local level are considered. In addition to aggregate cost modeling, the analysis focuses on the investment costs for the system components: overhead conductors, underground conductors, conduits, poles, transformers, services, street lighting, and station equipment for electricity distribution; and mains, services, regular and industrial measurement and regulation stations for natural gas distribution. The Box-Cox, log-log and additive models are compared to determine the best fitting cost functions. The Box-Cox form turns out to be superior to the other forms at the aggregate level and for network components. However, a linear additive form provides a better fit for end-user related components. The results show that, in addition to output variables and company-specific variables, various site-specific variables are statistically significant at the aggregate and disaggregate levels. Local electricity and natural gas distribution networks are characterized by a natural monopoly cost structure and economies of scale and density. The results provide evidence for the economies of scale and density for the aggregate electricity and natural gas distribution systems. However, distribution components have varying economic characteristics. The backbones of the networks (overhead conductors for electricity, and mains for natural gas) display economies of scale and density, but services in both systems and street lighting display diseconomies of scale and diseconomies of density. Finally multi-utility network cost analyses are presented for aggregate and disaggregate electricity and natural gas capital investments. Economies of scope analyses investigate whether providing electricity and natural gas jointly is economically advantageous, as compared to providing these products separately. Significant economies of scope are observed for both the total network and the underground capital investments.

Daily affect variability and context-specific alcohol consumption.

PubMed

Mohr, Cynthia D; Arpin, Sarah; McCabe, Cameron T

2015-11-01

Research explored the effects of variability in negative and positive affect on alcohol consumption, specifying daily fluctuation in affect as a critical form of emotion dysregulation. Using daily process methodology allows for a more objective calculation of affect variability relative to traditional self-reports. The present study models within-person negative and positive affect variabilities as predictors of context-specific consumption (i.e. solitary vs. social drinking), controlling for mean levels of affect. A community sample of moderate-to-heavy drinkers (n = 47; 49% women) from a US metropolitan area reported on affect and alcohol consumption thrice daily for 30 days via a handheld electronic interviewer. Within-person affect variability was calculated using daily standard deviations in positive and negative affect. Within person, greater negative and positive variabilities are related to greater daily solitary and social consumption. Across study days, mean levels of negative and positive affect variabilities related to greater social consumption between persons; yet, aggregated negative affect variability was related to less solitary consumption. Results affirm affect variability as a unique predictor of alcohol consumption, independent of mean affect levels. Yet, it is important to differentiate social context of consumption, as well as type of affect variability, particularly at the between-person level. These distinctions help clarify inconsistencies in the self-medication literature regarding associations between average levels of affect and consumption. Importantly, consistent within-person relationships for both variabilities support arguments that both negative and positive affect variabilities are detrimental and reflect an inability to regulate emotional experience. © 2015 Australasian Professional Society on Alcohol and other Drugs.

Variable selection based cotton bollworm odor spectroscopic detection

NASA Astrophysics Data System (ADS)

Lü, Chengxu; Gai, Shasha; Luo, Min; Zhao, Bo

2016-10-01

Aiming at rapid automatic pest detection based efficient and targeting pesticide application and shooting the trouble of reflectance spectral signal covered and attenuated by the solid plant, the possibility of near infrared spectroscopy (NIRS) detection on cotton bollworm odor is studied. Three cotton bollworm odor samples and 3 blank air gas samples were prepared. Different concentrations of cotton bollworm odor were prepared by mixing the above gas samples, resulting a calibration group of 62 samples and a validation group of 31 samples. Spectral collection system includes light source, optical fiber, sample chamber, spectrometer. Spectra were pretreated by baseline correction, modeled with partial least squares (PLS), and optimized by genetic algorithm (GA) and competitive adaptive reweighted sampling (CARS). Minor counts differences are found among spectra of different cotton bollworm odor concentrations. PLS model of all the variables was built presenting RMSEV of 14 and RV2 of 0.89, its theory basis is insect volatilizes specific odor, including pheromone and allelochemics, which are used for intra-specific and inter-specific communication and could be detected by NIR spectroscopy. 28 sensitive variables are selected by GA, presenting the model performance of RMSEV of 14 and RV2 of 0.90. Comparably, 8 sensitive variables are selected by CARS, presenting the model performance of RMSEV of 13 and RV2 of 0.92. CARS model employs only 1.5% variables presenting smaller error than that of all variable. Odor gas based NIR technique shows the potential for cotton bollworm detection.

A composite model including visfatin, tissue polypeptide-specific antigen, hyaluronic acid, and hematological variables for the diagnosis of moderate-to-severe fibrosis in nonalcoholic fatty liver disease: a preliminary study.

PubMed

Chwist, Alina; Hartleb, Marek; Lekstan, Andrzej; Kukla, Michał; Gutkowski, Krzysztof; Kajor, Maciej

2014-01-01

Histopathological risk factors for end-stage liver failure in patients with nonalcoholic fatty liver disease (NAFLD) include nonalcoholic steatohepatitis (NASH) and advanced liver fibrosis. There is a need for noninvasive diagnostic methods for these 2 conditions. The aim of this study was to investigate new laboratory variables with a predictive potential to detect advanced fibrosis (stages 2 and 3) in NAFLD. The study involved 70 patients with histologically proven NAFLD of varied severity. Additional laboratory variables included zonulin, haptoglobin, visfatin, adiponectin, leptin, tissue polypeptide-specific antigen (TPSA), hyaluronic acid, and interleukin 6. Patients with NASH (NAFLD activity score of ≥5) had significantly higher HOMA-IR values and serum levels of visfatin, haptoglobin, and zonulin as compared with those without NASH on histological examination. Advanced fibrosis was found in 16 patients (22.9%) and the risk factors associated with its prevalence were age, the ratio of erythrocyte count to red blood cell distribution width, platelet count, and serum levels of visfatin and TPSA. Based on these variables, we constructed a scoring system that differentiated between NAFLD patients with and without advanced fibrosis with a sensitivity of 75% and specificity of 100% (area under the receiver operating characteristic curve, 0.93). The scoring system based on the above variables allows to predict advanced fibrosis with high sensitivity and specificity. However, its clinical utility should be verified in further studies involving a larger number of patients.

Predictors of Cell Phone Use in Distracted Driving: Extending the Theory of Planned Behavior.

PubMed

Tian, Yan; Robinson, James D

2017-09-01

This study examines the predictors of six distracted driving behaviors, and the survey data partially support Ajzen's (1991) Theory of Planned Behavior (TPB). The data suggest that the attitude variable predicted intention to engage in all six distracted driving behaviors (reading and sending text messages, making and answering cell phone calls, reading/viewing social media, and posting on social media while driving). Extending the model to include past experience and the variable perceived safety of technology yielded an improvement in the prediction of the distraction variables. Specifically, past experience predicted all six distracted driving behaviors, and the variable perceived safety of technology predicted intentions to read/view social media and intention to post on social media while driving. The study provides evidence for the importance of incorporating expanded variables into the original TPB model to predict cell phone use behaviors while driving, and it suggests that it is essential to tailor campaign materials for each specific cell phone use behavior to reduce distracted driving.

Emotional Variability and Clarity in Depression and Social Anxiety

PubMed Central

Thompson, Renee J.; Boden, Matthew Tyler; Gotlib, Ian H.

2016-01-01

Recent research has underscored the importance of elucidating specific patterns of emotion that characterize mental disorders. We examined two emotion traits, emotional variability and emotional clarity, in relation to both categorical (diagnostic interview) and dimensional (self-report) measures of Major Depressive Disorder (MDD) and Social Anxiety Disorder (SAD) in women diagnosed with MDD only (n=35), SAD only (n=31), MDD and SAD (n=26), or no psychiatric disorder (n=38). Results of the categorical analyses suggest that elevated emotional variability and diminished emotional clarity are transdiagnostic of MDD and SAD. More specifically, emotional variability was elevated for MDD and SAD diagnoses compared to no diagnosis, showing an additive effect for co-occurring MDD and SAD. Similarly diminished levels of emotional clarity characterized all three clinical groups compared to the healthy control group. Dimensional findings suggest that whereas emotional variability is associated more consistently with depression than with social anxiety, emotional clarity is associated more consistently with social anxiety than with depression. Results are interpreted using a threshold- and dose-response framework. PMID:26371579

Developmental mechanisms underlying variable, invariant and plastic phenotypes

PubMed Central

Abley, Katie; Locke, James C. W.; Leyser, H. M. Ottoline

2016-01-01

Background Discussions of phenotypic robustness often consider scenarios where invariant phenotypes are optimal and assume that developmental mechanisms have evolved to buffer the phenotypes of specific traits against stochastic and environmental perturbations. However, plastic plant phenotypes that vary between environments or variable phenotypes that vary stochastically within an environment may also be advantageous in some scenarios. Scope Here the conditions under which invariant, plastic and variable phenotypes of specific traits may confer a selective advantage in plants are examined. Drawing on work from microbes and multicellular organisms, the mechanisms that may give rise to each type of phenotype are discussed. Conclusion In contrast to the view of robustness as being the ability of a genotype to produce a single, invariant phenotype, changes in a phenotype in response to the environment, or phenotypic variability within an environment, may also be delivered consistently (i.e. robustly). Thus, for some plant traits, mechanisms have probably evolved to produce plasticity or variability in a reliable manner. PMID:27072645

Correlates of alcohol consumption on heavy drinking occasions of young risky drinkers: event versus personal characteristics.

PubMed

Dietze, Paul; Agius, Paul A; Livingston, Michael; Callinan, Sarah; Jenkinson, Rebecca; Lim, Megan S C; Wright, Cassandra J C; Room, Robin

2017-08-01

Risky single-occasion drinking (RSOD) by young people is a serious public health issue, yet little is known about the specific circumstances of risky drinking occasions. This study examined the independent effects of event- and individual-specific variables on RSOD. Longitudinal cohort study measuring self-reported RSOD and event- and individual-specific variables across two drinking occasions approximately 1 year apart. Metropolitan Melbourne, Australia. A sample of 710 young risky drinkers aged between 18 and 25 years and defined as engaging in risky drinking practices (males: consumed alcohol in excess of 10 Australian Standard Drinks (ASD: 10 g ethanol) in a single occasion in the previous year; females: consumed alcohol in excess of seven ASD for females in a single occasion in the previous year). Random digit-dial telephone landline survey of the most recent heavy drinking occasion and socio-demographic variables. The primary outcome was the log of the total drinks consumed in the most recent heavy drinking occasion. Event-specific (e.g. number of drinking locations) and time-varying (e.g. weekly income) and time-invariant (e.g. sex) individual-specific variables were examined as correlates of total drinks consumed. Changes in event-specific characteristics including the length of the drinking occasion (Likelihood Ratio χ 2 (2) = 24.4, P < 0.001), the number of drinking locations (Wald χ 2 (1)  = 7.6, P = 0.006) and the number of different drink types (Wald χ 2 (1)  = 13.6, P < 0.001) were associated with increases in total drinks consumed, after adjustment for time-invariant and time-variant individual-specific variables such as gender, income level and weekly consumption. Few other effects were noted. Event-specific characteristics are important predictors of the number of drinks consumed during risky single occasion drinking (RSOD) and illustrate the importance of event contexts when considering interventions targeting RSOD. The total number of drinks consumed in a RSOD session appears to rise independently with the duration of the drinking event, the number of drinking locations and the number of different types of beverage consumed. © 2017 Society for the Study of Addiction.

Acute Mental Discomfort Associated with Suicide Behavior in a Clinical Sample of Patients with Affective Disorders: Ascertaining Critical Variables Using Artificial Intelligence Tools.

PubMed

Morales, Susana; Barros, Jorge; Echávarri, Orietta; García, Fabián; Osses, Alex; Moya, Claudia; Maino, María Paz; Fischman, Ronit; Núñez, Catalina; Szmulewicz, Tita; Tomicic, Alemka

2017-01-01

In efforts to develop reliable methods to detect the likelihood of impending suicidal behaviors, we have proposed the following. To gain a deeper understanding of the state of suicide risk by determining the combination of variables that distinguishes between groups with and without suicide risk. A study involving 707 patients consulting for mental health issues in three health centers in Greater Santiago, Chile. Using 345 variables, an analysis was carried out with artificial intelligence tools, Cross Industry Standard Process for Data Mining processes, and decision tree techniques. The basic algorithm was top-down, and the most suitable division produced by the tree was selected by using the lowest Gini index as a criterion and by looping it until the condition of belonging to the group with suicidal behavior was fulfilled. Four trees distinguishing the groups were obtained, of which the elements of one were analyzed in greater detail, since this tree included both clinical and personality variables. This specific tree consists of six nodes without suicide risk and eight nodes with suicide risk (tree decision 01, accuracy 0.674, precision 0.652, recall 0.678, specificity 0.670, F measure 0.665, receiver operating characteristic (ROC) area under the curve (AUC) 73.35%; tree decision 02, accuracy 0.669, precision 0.642, recall 0.694, specificity 0.647, F measure 0.667, ROC AUC 68.91%; tree decision 03, accuracy 0.681, precision 0.675, recall 0.638, specificity 0.721, F measure, 0.656, ROC AUC 65.86%; tree decision 04, accuracy 0.714, precision 0.734, recall 0.628, specificity 0.792, F measure 0.677, ROC AUC 58.85%). This study defines the interactions among a group of variables associated with suicidal ideation and behavior. By using these variables, it may be possible to create a quick and easy-to-use tool. As such, psychotherapeutic interventions could be designed to mitigate the impact of these variables on the emotional state of individuals, thereby reducing eventual risk of suicide. Such interventions may reinforce psychological well-being, feelings of self-worth, and reasons for living, for each individual in certain groups of patients.

Can Preoperative Magnetic Resonance Imaging Predict the Reparability of Massive Rotator Cuff Tears?

PubMed

Kim, Jung Youn; Park, Ji Seon; Rhee, Yong Girl

2017-06-01

Numerous studies have shown preoperative fatty infiltration of rotator cuff muscles to be strongly negatively correlated with the successful repair of massive rotator cuff tears (RCTs). To assess the association between factors identified on preoperative magnetic resonance imaging (MRI), especially infraspinatus fatty infiltration, and the reparability of massive RCTs. Case-control study; Level of evidence, 3. We analyzed a total of 105 patients with massive RCTs for whom MRI was performed ≤6 months before arthroscopic procedures. The mean age of the patients was 62.7 years (range, 46-83 years), and 46 were men. Among them, complete repair was possible in 50 patients (48%) and not possible in 55 patients (52%). The tangent sign, fatty infiltration of the rotator cuff, and Patte classification were evaluated as predictors of reparability. Using the receiver operating characteristic curve and the area under the curve (AUC), the prediction accuracy of each variable and combinations of variables were measured. Reparability was associated with fatty infiltration of the supraspinatus ( P = .0045) and infraspinatus ( P < .001) muscles, the tangent sign ( P = .0033), and the Patte classification ( P < .001) but not with fatty infiltration of the subscapularis and teres minor ( P = .425 and .132, respectively). The cut-off values for supraspinatus and infraspinatus fatty infiltration were grade >3 and grade >2, respectively. The examination of single variables revealed that infraspinatus fatty infiltration showed the highest AUC value (0.812; sensitivity: 0.86; specificity: 0.76), while the tangent sign showed the lowest AUC value (0.626; sensitivity: 0.38; specificity: 0.87). Among 2-variable combinations, the combination of infraspinatus fatty infiltration and the Patte classification showed the highest AUC value (0.874; sensitivity: 0.54; specificity: 0.96). The combination of 4 variables, that is, infraspinatus and supraspinatus fatty infiltration, the tangent sign, and the Patte classification, had an AUC of 0.866 (sensitivity: 0.28; specificity: 0.98), which was lower than the highest AUC value (0.874; sensitivity: 0.54; specificity: 0.96) among the 2-variable combinations. The tangent sign or Patte classification alone was not a predictive indicator of the reparability of massive RCTs. Among single variables, infraspinatus fatty infiltration was the most effective in predicting reparability, while the combination of Goutallier classification <3 of the infraspinatus and Patte classification ≤2 of the rotator cuff muscles was the most predictive among the combinations of variables. This information may help predict the reparability of massive RCTs.

Screening and Identification of a Phage Display Derived Peptide That Specifically Binds to the CD44 Protein Region Encoded by Variable Exons.

PubMed

Zhang, Dan; Jia, Huan; Li, Weiming; Hou, Yingchun; Lu, Shaoying; He, Shuixiang

2016-01-01

CD44, especially the isoforms with variable exons (CD44v), is a promising biomarker for the detection of cancer. To develop a CD44v-specific probe, we screened a 7-mer phage peptide library against the CD44v3-v10 protein using an improved subtractive method. The consensus sequences with the highest frequency (designated CV-1) emerged after four rounds of panning. The binding affinity and specificity of the CV-1 phage and the synthesized peptide for the region of CD44 encoded by the variable exons were confirmed using enzyme-linked immunosorbent assay and competitive inhibition assays. Furthermore, the binding of the CV-1 probe to gastric cancer cells and tissues was validated using immunofluorescence and immunohistochemistry assays. CV-1 sensitively and specifically bound to CD44v on cancer cells and tissues. Thus, CV-1 has the potential to serve as a promising probe for cancer molecular imaging and target therapy. © 2015 Society for Laboratory Automation and Screening.

Socio-Ecological Variables Associated with Context-Specific Sitting Time in Belgian Older Adults: A One-Year Follow-Up Study

PubMed Central

Busschaert, Cedric; Scherrens, Anne-Lore; De Bourdeaudhuij, Ilse; Cardon, Greet; Van Cauwenberg, Jelle; De Cocker, Katrien

2016-01-01

Introduction Knowledge about variables associated with context-specific sitting time in older adults is limited. Therefore, this study explored cross-sectional and longitudinal associations of socio-demographic, social-cognitive, physical-environmental and health-related variables with sitting during TV viewing, computer use and motorized transport in older adults. Methods A sample of Belgian older adults completed structured interviews on context-specific sitting time and associated variables using a longitudinal study design. Objective measurements of grip strength and physical performance were also completed. Complete baseline data were available of 258 participants (73.98±6.16 years) of which 229 participants remained in the study at one year follow-up (retention rate: 91.60%). Cross-sectional correlates (baseline data) and longitudinal predictors (change-scores in relation with change in sitting time) were explored through multiple linear regression analyses. Results Per context-specific sitting time, most of the cross-sectional correlates differed from the longitudinal predictors. Increases over time in enjoyment of watching TV (+one unit), encouragement of partner to watch less TV (+one unit) and TV time of partner (+30.0 min/day) were associated with respectively 9.1 min/day (p<0.001), 16.0 min/day (p<0.001) and 12.0 min/day (p<0.001) more sitting during TV viewing at follow-up. Increases over time in enjoyment of using a computer (+one unit), the number of smartphones and tablets (+1) and computer use of the partner (+30.0 min/day) were associated with respectively 5.5 min/day (p < .01), 10.4 min/day (p < .05) and 3.0 min/day (p < .05) more sitting during computer use at follow-up. An increase over time in self-efficacy regarding taking a bicycle or walking was associated with 2.9 min/day (p < .05) less sitting during motorized transport at follow-up. Conclusions The results stressed the importance of looking at separate contexts of sitting. Further, the results highlighted the importance of longitudinal research in order to reveal which changes in particular variables predicted changes in context-specific sitting time. Variables at the social-cognitive level were most frequently related to context-specific sitting. PMID:27997603

Multiple and variable speed electrical generator systems for large wind turbines

NASA Technical Reports Server (NTRS)

Andersen, T. S.; Hughes, P. S.; Kirschbaum, H. S.; Mutone, G. A.

1982-01-01

A cost effective method to achieve increased wind turbine generator energy conversion and other operational benefits through variable speed operation is presented. Earlier studies of multiple and variable speed generators in wind turbines were extended for evaluation in the context of a specific large sized conceptual design. System design and simulation have defined the costs and performance benefits which can be expected from both two speed and variable speed configurations.

[Mix 10] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2011-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 4] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2011-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 5] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2011-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

Variable-cycle engines for supersonic cruise aircraft

NASA Technical Reports Server (NTRS)

Willis, E.

1976-01-01

Progress and the current status of the Variable Cycle Engine (VCE) study are reviewed with emphasis placed on the impact of technology advancements and design specifications. A large variety of VCE concepts are also examined.

[Mix 13] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2007-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 3] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2010-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 14] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2007-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 7] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2004-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 16] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2004-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 6] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2007-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 12] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2004-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 1] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2010-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 2] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2010-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 8] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2007-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 11] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2007-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 15] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2004-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

[Mix 9] HMACP mixture design : combined gradation.

DOT National Transportation Integrated Search

2007-01-01

Getting Started: Begin with the Combined Gradations or Summary sheet. Here you will select dependent variables such as specification year, mix type, asphalt content, combined aggregate, and others. These variable will affect the calculation of other ...

Learning (Not) to Talk about Race: Investigating What Doctoral Students Learn about Race Variables and Statistical Modeling

ERIC Educational Resources Information Center

Armijo, Michael; Lundy-Wagner, Valerie; Merrill, Elizabeth

2012-01-01

This paper asks how doctoral students understand the use of race variables in statistical modeling. More specifically, it examines how doctoral students at two universities are trained to define, operationalize, and analyze race variables. The authors interviewed students and instructors in addition to conducting a document analysis of their texts…

Temporal Variability and Stability in Infant-Directed Sung Speech: Evidence for Language-Specific Patterns

ERIC Educational Resources Information Center

Falk, Simone

2011-01-01

In this paper, sung speech is used as a methodological tool to explore temporal variability in the timing of word-internal consonants and vowels. It is hypothesized that temporal variability/stability becomes clearer under the varying rhythmical conditions induced by song. This is explored cross-linguistically in German--a language that exhibits a…

Comparing Indirect Effects in SEM: A Sequential Model Fitting Method Using Covariance-Equivalent Specifications

ERIC Educational Resources Information Center

Chan, Wai

2007-01-01

In social science research, an indirect effect occurs when the influence of an antecedent variable on the effect variable is mediated by an intervening variable. To compare indirect effects within a sample or across different samples, structural equation modeling (SEM) can be used if the computer program supports model fitting with nonlinear…

76 FR 34685 - Energy Conservation Program for Certain Commercial and Industrial Equipment: Decision and Order...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-14

.... The waiver is specific to the Daikin VRV III-PB variable refrigerant flow (VRF) multi-split commercial... this notice to test and rate its VRV III-PB variable refrigerant flow (VRF) multi-split commercial heat... Institute (ANSI/ AHRI) Standard 1230-2010, ``Performance Rating of Variable Refrigerant Flow (VRF) Multi...

Variability in "DIBELS Next" Progress Monitoring Measures for Students at Risk for Reading Difficulties

ERIC Educational Resources Information Center

O'Keeffe, Breda V.; Bundock, Kaitlin; Kladis, Kristin L.; Yan, Rui; Nelson, Kat

2017-01-01

Previous research on curriculum-based measurement of oral reading fluency (CBM ORF) found high levels of variability around the estimates of students' fluency; however, little research has studied the issue of variability specifically with well-designed passage sets and a sample of students who scored below benchmark for the purpose of progress…

Socio-Demographic, Social-Cognitive, Health-Related and Physical Environmental Variables Associated with Context-Specific Sitting Time in Belgian Adolescents: A One-Year Follow-Up Study.

PubMed

Busschaert, Cedric; Ridgers, Nicola D; De Bourdeaudhuij, Ilse; Cardon, Greet; Van Cauwenberg, Jelle; De Cocker, Katrien

2016-01-01

More knowledge is warranted about multilevel ecological variables associated with context-specific sitting time among adolescents. The present study explored cross-sectional and longitudinal associations of ecological domains of sedentary behaviour, including socio-demographic, social-cognitive, health-related and physical-environmental variables with sitting during TV viewing, computer use, electronic gaming and motorized transport among adolescents. For this longitudinal study, a sample of Belgian adolescents completed questionnaires at school on context-specific sitting time and associated ecological variables. At baseline, complete data were gathered from 513 adolescents (15.0±1.7 years). At one-year follow-up, complete data of 340 participants were available (retention rate: 66.3%). Multilevel linear regression analyses were conducted to explore cross-sectional correlates (baseline variables) and longitudinal predictors (change scores variables) of context-specific sitting time. Social-cognitive correlates/predictors were most frequently associated with context-specific sitting time. Longitudinal analyses revealed that increases over time in considering it pleasant to watch TV (p < .001), in perceiving TV watching as a way to relax (p < .05), in TV time of parents/care givers (p < .01) and in TV time of siblings (p < .001) were associated with more sitting during TV viewing at follow-up. Increases over time in considering it pleasant to use a computer in leisure time (p < .01) and in the computer time of siblings (p < .001) were associated with more sitting during computer use at follow-up. None of the changes in potential predictors were significantly related to changes in sitting during motorized transport or during electronic gaming. Future intervention studies aiming to decrease TV viewing and computer use should acknowledge the importance of the behaviour of siblings and the pleasure adolescents experience during these screen-related behaviours. In addition, more time parents or care givers spent sitting may lead to more sitting during TV viewing of the adolescents, so that a family-based approach may be preferable for interventions. Experimental study designs are warranted to confirm the present findings.

Variability among the Most Rapidly Evolving Plastid Genomic Regions is Lineage-Specific: Implications of Pairwise Genome Comparisons in Pyrus (Rosaceae) and Other Angiosperms for Marker Choice

PubMed Central

Ter-Voskanyan, Hasmik; Allgaier, Martin; Borsch, Thomas

2014-01-01

Plastid genomes exhibit different levels of variability in their sequences, depending on the respective kinds of genomic regions. Genes are usually more conserved while noncoding introns and spacers evolve at a faster pace. While a set of about thirty maximum variable noncoding genomic regions has been suggested to provide universally promising phylogenetic markers throughout angiosperms, applications often require several regions to be sequenced for many individuals. Our project aims to illuminate evolutionary relationships and species-limits in the genus Pyrus (Rosaceae)—a typical case with very low genetic distances between taxa. In this study, we have sequenced the plastid genome of Pyrus spinosa and aligned it to the already available P. pyrifolia sequence. The overall p-distance of the two Pyrus genomes was 0.00145. The intergenic spacers between ndhC–trnV, trnR–atpA, ndhF–rpl32, psbM–trnD, and trnQ–rps16 were the most variable regions, also comprising the highest total numbers of substitutions, indels and inversions (potentially informative characters). Our comparative analysis of further plastid genome pairs with similar low p-distances from Oenothera (representing another rosid), Olea (asterids) and Cymbidium (monocots) showed in each case a different ranking of genomic regions in terms of variability and potentially informative characters. Only two intergenic spacers (ndhF–rpl32 and trnK–rps16) were consistently found among the 30 top-ranked regions. We have mapped the occurrence of substitutions and microstructural mutations in the four genome pairs. High AT content in specific sequence elements seems to foster frequent mutations. We conclude that the variability among the fastest evolving plastid genomic regions is lineage-specific and thus cannot be precisely predicted across angiosperms. The often lineage-specific occurrence of stem-loop elements in the sequences of introns and spacers also governs lineage-specific mutations. Sequencing whole plastid genomes to find markers for evolutionary analyses is therefore particularly useful when overall genetic distances are low. PMID:25405773

Socio-Demographic, Social-Cognitive, Health-Related and Physical Environmental Variables Associated with Context-Specific Sitting Time in Belgian Adolescents: A One-Year Follow-Up Study

PubMed Central

Busschaert, Cedric; Ridgers, Nicola D.; De Bourdeaudhuij, Ilse; Cardon, Greet; Van Cauwenberg, Jelle; De Cocker, Katrien

2016-01-01

Introduction More knowledge is warranted about multilevel ecological variables associated with context-specific sitting time among adolescents. The present study explored cross-sectional and longitudinal associations of ecological domains of sedentary behaviour, including socio-demographic, social-cognitive, health-related and physical-environmental variables with sitting during TV viewing, computer use, electronic gaming and motorized transport among adolescents. Methods For this longitudinal study, a sample of Belgian adolescents completed questionnaires at school on context-specific sitting time and associated ecological variables. At baseline, complete data were gathered from 513 adolescents (15.0±1.7 years). At one-year follow-up, complete data of 340 participants were available (retention rate: 66.3%). Multilevel linear regression analyses were conducted to explore cross-sectional correlates (baseline variables) and longitudinal predictors (change scores variables) of context-specific sitting time. Results Social-cognitive correlates/predictors were most frequently associated with context-specific sitting time. Longitudinal analyses revealed that increases over time in considering it pleasant to watch TV (p < .001), in perceiving TV watching as a way to relax (p < .05), in TV time of parents/care givers (p < .01) and in TV time of siblings (p < .001) were associated with more sitting during TV viewing at follow-up. Increases over time in considering it pleasant to use a computer in leisure time (p < .01) and in the computer time of siblings (p < .001) were associated with more sitting during computer use at follow-up. None of the changes in potential predictors were significantly related to changes in sitting during motorized transport or during electronic gaming. Conclusions Future intervention studies aiming to decrease TV viewing and computer use should acknowledge the importance of the behaviour of siblings and the pleasure adolescents experience during these screen-related behaviours. In addition, more time parents or care givers spent sitting may lead to more sitting during TV viewing of the adolescents, so that a family-based approach may be preferable for interventions. Experimental study designs are warranted to confirm the present findings. PMID:27936073

Interannual Variation in Phytoplankton Class-Specific Primary Production at a Global Scale

NASA Technical Reports Server (NTRS)

Rousseaux, Cecile Severine; Gregg, Watson W.

2014-01-01

We used the NASA Ocean Biogeochemical Model (NOBM) combined with remote sensing data via assimilation to evaluate the contribution of 4 phytoplankton groups to the total primary production. First we assessed the contribution of each phytoplankton groups to the total primary production at a global scale for the period 1998-2011. Globally, diatoms were the group that contributed the most to the total phytoplankton production (50, the equivalent of 20 PgC y-1. Coccolithophores and chlorophytes each contributed to 20 (7 PgC y-1 of the total primary production and cyanobacteria represented about 10 (4 PgC y(sub-1) of the total primary production. Primary production by diatoms was highest in high latitude (45) and in major upwelling systems (Equatorial Pacific and Benguela system). We then assessed interannual variability of this group-specific primary production over the period 1998-2011. Globally the annual relative contribution of each phytoplankton groups to the total primary production varied by maximum 4 (1-2 PgC y-1. We assessed the effects of climate variability on the class-specific primary production using global (i.e. Multivariate El Nio Index, MEI) and regional climate indices (e.g. Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO)). Most interannual variability occurred in the Equatorial Pacific and was associated with climate variability as indicated by significant correlation (p 0.05) between the MEI and the class-specific primary production from all groups except coccolithophores. In the Atlantic, climate variability as indicated by NAO was significantly correlated to the primary production of 2 out of the 4 groups in the North Central Atlantic (diatomscyanobacteria) and in the North Atlantic (chlorophytes and coccolithophores). We found that climate variability as indicated by SAM had only a limited effect on the class-specific primary production in the Southern Ocean. These results provide a modeling and data assimilation perspective to phytoplankton partitioning of primary production and contribute to our understanding of the dynamics of the carbon cycle in the oceans at a global scale.

International Endometrial Tumor Analysis (IETA) terminology in women with postmenopausal bleeding and sonographic endometrial thickness ≥ 4.5 mm: agreement and reliability study.

PubMed

Sladkevicius, P; Installé, A; Van Den Bosch, T; Timmerman, D; Benacerraf, B; Jokubkiene, L; Di Legge, A; Votino, A; Zannoni, L; De Moor, B; De Cock, B; Van Calster, B; Valentin, L

2018-02-01

To estimate intra- and interrater agreement and reliability with regard to describing ultrasound images of the endometrium using the International Endometrial Tumor Analysis (IETA) terminology. Four expert and four non-expert raters assessed videoclips of transvaginal ultrasound examinations of the endometrium obtained from 99 women with postmenopausal bleeding and sonographic endometrial thickness ≥ 4.5 mm but without fluid in the uterine cavity. The following features were rated: endometrial echogenicity, endometrial midline, bright edge, endometrial-myometrial junction, color score, vascular pattern, irregularly branching vessels and color splashes. The color content of the endometrial scan was estimated using a visual analog scale graded from 0 to 100. To estimate intrarater agreement and reliability, the same videoclips were assessed twice with a minimum of 2 months' interval. The raters were blinded to their own results and to those of the other raters. Interrater differences in the described prevalence of most IETA variables were substantial, and some variable categories were observed rarely. Specific agreement was poor for variables with many categories. For binary variables, specific agreement was better for absence than for presence of a category. For variables with more than two outcome categories, specific agreement for expert and non-expert raters was best for not-defined endometrial midline (93% and 96%), regular endometrial-myometrial junction (72% and 70%) and three-layer endometrial pattern (67% and 56%). The grayscale ultrasound variable with the best reliability was uniform vs non-uniform echogenicity (multirater kappa (κ), 0.55 for expert and 0.52 for non-expert raters), and the variables with the lowest reliability were appearance of the endometrial-myometrial junction (κ, 0.25 and 0.16) and the nine-category endometrial echogenicity variable (κ, 0.29 and 0.28). The most reliable color Doppler variable was color score (mean weighted κ, 0.77 and 0.69). Intra- and interrater agreement and reliability were similar for experts and non-experts. Inter- and intrarater agreement and reliability when using IETA terminology were limited. This may have implications when assessing the association between a particular ultrasound feature and a specific histological diagnosis, because lack of reproducibility reduces the reliability of the association between a feature and the outcome. Future studies should investigate whether using fewer categories of variable or offering practical training could improve agreement and reliability. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Temporal Proof Methodologies for Real-Time Systems,

DTIC Science & Technology

1990-09-01

real time systems that communicate either through shared variables or by message passing and real time issues such as time-outs, process priorities (interrupts) and process scheduling. The authors exhibit two styles for the specification of real - time systems . While the first approach uses bounded versions of temporal operators the second approach allows explicit references to time through a special clock variable. Corresponding to two styles of specification the authors present and compare two fundamentally different proof

Differential sensory fMRI signatures in autism and schizophrenia: Analysis of amplitude and trial-to-trial variability.

PubMed

Haigh, Sarah M; Gupta, Akshat; Barb, Scott M; Glass, Summer A F; Minshew, Nancy J; Dinstein, Ilan; Heeger, David J; Eack, Shaun M; Behrmann, Marlene

2016-08-01

Autism and schizophrenia share multiple phenotypic and genotypic markers, and there is ongoing debate regarding the relationship of these two disorders. To examine whether cortical dynamics are similar across these disorders, we directly compared fMRI responses to visual, somatosensory and auditory stimuli in adults with autism (N=15), with schizophrenia (N=15), and matched controls (N=15). All participants completed a one-back letter detection task presented at fixation (to control attention) while task-irrelevant sensory stimulation was delivered to the different modalities. We focused specifically on the response amplitudes and the variability in sensory fMRI responses of the two groups, given the evidence of greater trial-to-trial variability in adults with autism. Both autism and schizophrenia individuals showed weaker signal-to-noise ratios (SNR) in sensory-evoked responses compared to controls (d>0.42), but for different reasons. For the autism group, the fMRI response amplitudes were indistinguishable from controls but were more variable trial-to-trial (d=0.47). For the schizophrenia group, response amplitudes were smaller compared to autism (d=0.44) and control groups (d=0.74), but were not significantly more variable (d<0.29). These differential group profiles suggest (1) that greater trial-to-trial variability in cortical responses may be specific to autism and is not a defining characteristic of schizophrenia, and (2) that blunted response amplitudes may be characteristic of schizophrenia. The relationship between the amplitude and the variability of cortical activity might serve as a specific signature differentiating these neurodevelopmental disorders. Identifying the neural basis of these responses and their relationship to the underlying genetic bases may substantially enlighten the understanding of both disorders. Copyright © 2016 Elsevier B.V. All rights reserved.

Simulations of the Boreal Winter Upper Mesosphere and Lower Thermosphere With Meteorological Specifications in SD-WACCM-X

NASA Astrophysics Data System (ADS)

Sassi, Fabrizio; Siskind, David E.; Tate, Jennifer L.; Liu, Han-Li; Randall, Cora E.

2018-04-01

We investigate the benefit of high-altitude nudging in simulations of the structure and short-term variability of the upper mesosphere and lower thermosphere (UMLT) dynamical meteorology during boreal winter, specifically around the time of the January 2009 sudden stratospheric warming. We compare simulations using the Specified Dynamics, Whole Atmosphere Community Climate Model, extended version, nudged using atmospheric specifications generated by the Navy Operational Global Atmospheric Prediction System, Advanced Level Physics High Altitude. Two sets of simulations are carried out: one uses nudging over a vertical domain from 0 to 90 km; the other uses nudging over a vertical domain from 0 to 50 km. The dynamical behavior is diagnosed from ensemble mean and standard deviation of winds, temperature, and zonal accelerations due to resolved and parameterized waves. We show that the dynamical behavior of the UMLT is quite different in the two experiments, with prominent differences in the structure and variability of constituent transport. We compare the results of our numerical experiments to observations of carbon monoxide by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer to show that the high-altitude nudging is capable of reproducing with high fidelity the observed variability, and traveling planetary waves are a crucial component of the dynamics. The results of this study indicate that to capture the key physical processes that affect short-term variability (defined as the atmospheric behavior within about 10 days of a stratospheric warming) in the UMLT, specification of the atmospheric state in the stratosphere alone is not sufficient, and upper atmospheric specifications are needed.

Universal Quantum Computing with Arbitrary Continuous-Variable Encoding.

PubMed

Lau, Hoi-Kwan; Plenio, Martin B

2016-09-02

Implementing a qubit quantum computer in continuous-variable systems conventionally requires the engineering of specific interactions according to the encoding basis states. In this work, we present a unified formalism to conduct universal quantum computation with a fixed set of operations but arbitrary encoding. By storing a qubit in the parity of two or four qumodes, all computing processes can be implemented by basis state preparations, continuous-variable exponential-swap operations, and swap tests. Our formalism inherits the advantages that the quantum information is decoupled from collective noise, and logical qubits with different encodings can be brought to interact without decoding. We also propose a possible implementation of the required operations by using interactions that are available in a variety of continuous-variable systems. Our work separates the "hardware" problem of engineering quantum-computing-universal interactions, from the "software" problem of designing encodings for specific purposes. The development of quantum computer architecture could hence be simplified.

Universal Quantum Computing with Arbitrary Continuous-Variable Encoding

NASA Astrophysics Data System (ADS)

Lau, Hoi-Kwan; Plenio, Martin B.

2016-09-01

Implementing a qubit quantum computer in continuous-variable systems conventionally requires the engineering of specific interactions according to the encoding basis states. In this work, we present a unified formalism to conduct universal quantum computation with a fixed set of operations but arbitrary encoding. By storing a qubit in the parity of two or four qumodes, all computing processes can be implemented by basis state preparations, continuous-variable exponential-swap operations, and swap tests. Our formalism inherits the advantages that the quantum information is decoupled from collective noise, and logical qubits with different encodings can be brought to interact without decoding. We also propose a possible implementation of the required operations by using interactions that are available in a variety of continuous-variable systems. Our work separates the "hardware" problem of engineering quantum-computing-universal interactions, from the "software" problem of designing encodings for specific purposes. The development of quantum computer architecture could hence be simplified.

Richer concepts are better remembered: number of features effects in free recall

PubMed Central

Hargreaves, Ian S.; Pexman, Penny M.; Johnson, Jeremy C.; Zdrazilova, Lenka

2012-01-01

Many models of memory build in a term for encoding variability, the observation that there can be variability in the richness or extensiveness of processing at encoding, and that this variability has consequences for retrieval. In four experiments, we tested the expectation that encoding variability could be driven by the properties of the to-be-remembered item. Specifically, that concepts associated with more semantic features would be better remembered than concepts associated with fewer semantic features. Using feature listing norms we selected sets of items for which people tend to list higher numbers of features (high NoF) and items for which people tend to list lower numbers of features (low NoF). Results showed more accurate free recall for high NoF concepts than for low NoF concepts in expected memory tasks (Experiments 1–3) and also in an unexpected memory task (Experiment 4). This effect was not the result of associative chaining between study items (Experiment 3), and can be attributed to the amount of item-specific processing that occurs at study (Experiment 4). These results provide evidence that stimulus-specific differences in processing at encoding have consequences for explicit memory retrieval. PMID:22514526

Identification of the need for home visiting nurse: development of a new assessment tool.

PubMed

Taguchi, Atsuko; Nagata, Satoko; Naruse, Takashi; Kuwahara, Yuki; Yamaguchi, Takuhiro; Murashima, Sachiyo

2014-01-01

To develop a Home Visiting Nursing Service Need Assessment Form (HVNS-NAF) to standardize the decision about the need for home visiting nursing service. The sample consisted of older adults who had received coordinated services by care managers. We defined the need for home visiting nursing service by elderly individuals as the decision of the need by a care manager so that the elderly can continue to live independently. Explanatory variables included demographic factors, medical procedure, severity of illness, and caregiver variables. Multiple logistic regression was carried out after univariate analyses to decide the variables to include and the weight of each variable in the HVNS-NAF. We then calculated the sensitivity and specificity of each cutoff value, and defined the score with the highest sensitivity and specificity as the cutoff value. Nineteen items were included in the final HVNS-NAF. When the cutoff value was 2 points, the sensitivity was 77.0%, specificity 68.5%, and positive predictive value 56.8%. HVNS-NAF is the first validated standard based on characteristics of elderly clients who required home visiting nursing service. Using the HVNS-NAF may result in reducing the unmet need for home visiting nursing service and preventing hospitalization.

Plant Trait Variation along an Altitudinal Gradient in Mediterranean High Mountain Grasslands: Controlling the Species Turnover Effect

PubMed Central

Pescador, David S.; de Bello, Francesco; Valladares, Fernando; Escudero, Adrián

2015-01-01

Assessing changes in plant functional traits along gradients is useful for understanding the assembly of communities and their response to global and local environmental drivers. However, these changes may reflect the effects of species composition (i.e. composition turnover), species abundance (i.e. species interaction), and intra-specific trait variability (i.e. species plasticity). In order to determine the relevance of the latter, trait variation can be assessed under minimal effects of composition turnover. Nine sampling sites were established along an altitudinal gradient in a Mediterranean high mountain grassland community with low composition turnover (Madrid, Spain; 1940 m–2419 m). Nine functional traits were also measured for ten individuals of around ten plant species at each site, for a total of eleven species across all sites. The relative importance of different sources of variability (within/between site and intra-/inter-specific functional diversity) and trait variation at species and community level along the considered gradients were explored. We found a weak individual species response to altitude and other environmental variables although in some cases, individuals were smaller and leaves were thicker at higher elevations. This lack of species response was most likely due to greater within- than between-site species variation. At the community level, inter-specific functional diversity was generally greater than the intra-specific component except for traits linked to leaf element content (leaf carbon content, leaf nitrogen content, δ13C and δ15N). Inter-specific functional diversity decreased with lower altitude for four leaf traits (specific leaf area, leaf dry matter content, δ13C and δ15N), suggesting trait convergence between species at lower elevations, where water shortage may have a stronger environmental filtering effect than colder temperatures at higher altitudes. Our results suggest that, within a vegetation type encompassing various environmental gradients, both, changes in species abundance and intra-specific trait variability adjust for the community functional response to environmental changes. PMID:25774532

Plant trait variation along an altitudinal gradient in mediterranean high mountain grasslands: controlling the species turnover effect.

PubMed

Pescador, David S; de Bello, Francesco; Valladares, Fernando; Escudero, Adrián

2015-01-01

Assessing changes in plant functional traits along gradients is useful for understanding the assembly of communities and their response to global and local environmental drivers. However, these changes may reflect the effects of species composition (i.e. composition turnover), species abundance (i.e. species interaction), and intra-specific trait variability (i.e. species plasticity). In order to determine the relevance of the latter, trait variation can be assessed under minimal effects of composition turnover. Nine sampling sites were established along an altitudinal gradient in a Mediterranean high mountain grassland community with low composition turnover (Madrid, Spain; 1940 m-2419 m). Nine functional traits were also measured for ten individuals of around ten plant species at each site, for a total of eleven species across all sites. The relative importance of different sources of variability (within/between site and intra-/inter-specific functional diversity) and trait variation at species and community level along the considered gradients were explored. We found a weak individual species response to altitude and other environmental variables although in some cases, individuals were smaller and leaves were thicker at higher elevations. This lack of species response was most likely due to greater within- than between-site species variation. At the community level, inter-specific functional diversity was generally greater than the intra-specific component except for traits linked to leaf element content (leaf carbon content, leaf nitrogen content, δ13C and δ15N). Inter-specific functional diversity decreased with lower altitude for four leaf traits (specific leaf area, leaf dry matter content, δ13C and δ15N), suggesting trait convergence between species at lower elevations, where water shortage may have a stronger environmental filtering effect than colder temperatures at higher altitudes. Our results suggest that, within a vegetation type encompassing various environmental gradients, both, changes in species abundance and intra-specific trait variability adjust for the community functional response to environmental changes.

Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) processing speed scores as measures of noncredible responding: The third generation of embedded performance validity indicators.

PubMed

Erdodi, Laszlo A; Abeare, Christopher A; Lichtenstein, Jonathan D; Tyson, Bradley T; Kucharski, Brittany; Zuccato, Brandon G; Roth, Robert M

2017-02-01

Research suggests that select processing speed measures can also serve as embedded validity indicators (EVIs). The present study examined the diagnostic utility of Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) subtests as EVIs in a mixed clinical sample of 205 patients medically referred for neuropsychological assessment (53.3% female, mean age = 45.1). Classification accuracy was calculated against 3 composite measures of performance validity as criterion variables. A PSI ≤79 produced a good combination of sensitivity (.23-.56) and specificity (.92-.98). A Coding scaled score ≤5 resulted in good specificity (.94-1.00), but low and variable sensitivity (.04-.28). A Symbol Search scaled score ≤6 achieved a good balance between sensitivity (.38-.64) and specificity (.88-.93). A Coding-Symbol Search scaled score difference ≥5 produced adequate specificity (.89-.91) but consistently low sensitivity (.08-.12). A 2-tailed cutoff on the Coding/Symbol Search raw score ratio (≤1.41 or ≥3.57) produced acceptable specificity (.87-.93), but low sensitivity (.15-.24). Failing ≥2 of these EVIs produced variable specificity (.81-.93) and sensitivity (.31-.59). Failing ≥3 of these EVIs stabilized specificity (.89-.94) at a small cost to sensitivity (.23-.53). Results suggest that processing speed based EVIs have the potential to provide a cost-effective and expedient method for evaluating the validity of cognitive data. Given their generally low and variable sensitivity, however, they should not be used in isolation to determine the credibility of a given response set. They also produced unacceptably high rates of false positive errors in patients with moderate-to-severe head injury. Combining evidence from multiple EVIs has the potential to improve overall classification accuracy. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Predictors of academic performance in the discipline-specific bioscience paper: a retrospective qualitative study.

PubMed

Khareedi, R

2018-05-01

The cohort of students enrolled in the discipline-specific bioscience paper reflects a structural diversity in that it includes students of multiple ethnicities, varied age groups, differing scholastic and life experiences. These divergent identities of students are known to influence academic performance. The purpose of this retrospective quantitative study was to determine the ability of a set of variables such as age, gender, ethnicity, level of prior education, the place from which prior education was obtained, work experience and prior academic achievement to predict academic performance in the discipline-specific bioscience paper. The sample for this study was a purposive sample of all oral health students who had enrolled in the paper at the Auckland University of Technology from 2011 to 2014. The desensitised empirical data of 116 students from the University's database were subject to multivariable regression analysis. Pearson's correlation coefficients were calculated. Prior academic achievement was a statistically significant predictor variable (P < 0.001) for the academic performance in the discipline-specific bioscience paper and was also positively correlated (r = 0.641, P < 0.001) to the grades in the discipline-specific bioscience paper. Prior academic achievement was the only variable that was demonstrated to be correlated to and predictive of the academic performance in the discipline-specific bioscience paper. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Goal orientation, perceived task outcome and task demands in mathematics tasks: effects on students' attitude in actual task settings.

PubMed

Seegers, Gerard; van Putten, Cornelis M; de Brabander, Cornelis J

2002-09-01

In earlier studies, it has been found that students' domain-specific cognitions and personal learning goals (goal orientation) influence task-specific appraisals of actual learning tasks. The relations between domain-specific and task-specific variables have been specified in the model of adaptive learning. In this study, additional influences, i.e., perceived task outcome on a former occasion and variations in task demands, were investigated. The purpose of this study was to identify personality and situational variables that mediate students' attitude when confronted with a mathematics task. Students worked on a mathematics task in two subsequent sessions. Effects of perceived task outcome at the first session on students' attitude at the second session were investigated. In addition, we investigated how differences in task demands influenced students' attitude. Variations in task demands were provoked by different conditions in task-instruction. In one condition, students were told that the result on the test would add to their mark on mathematics. This outcome orienting condition was contrasted with a task-orienting condition where students were told that the results on the test would not be used to give individual grades. Participants were sixth grade students (N = 345; aged 11-12 years) from 14 primary schools. Multivariate and univariate analyses of (co)variance were applied to the data. Independent variables were goal orientation, task demands, and perceived task outcome, with task-specific variables (estimated competence for the task, task attraction, task relevance, and willingness to invest effort) as the dependent variables. The results showed that previous perceived task outcome had a substantial impact on students' attitude. Additional but smaller effects were found for variation in task demands. Furthermore, effects of previous perceived task outcome and task demands were related to goal orientation. The resulting pattern confirmed that, in general, performance-oriented learning goals emphasised the negative impact of failure experiences, whereas task-oriented learning goals had a strengthening effect on how success experiences influenced students' attitude.

Temporal change in biological community structure in the Fountain Creek basin, Colorado, 2001-2008

USGS Publications Warehouse

Zuellig, Robert E.; Bruce, James F.; Stogner, Sr., Robert W.

2010-01-01

In 2001, the U.S. Geological Survey, in cooperation with Colorado Springs City Engineering, began a study to better understand the relations between environmental characteristics and biological communities in the Fountain Creek basin in order to aide water-resource management and guide future monitoring activities. To accomplish this task, environmental (streamflow, habitat, and water chemistry) and biological (fish and macroinvertebrate) data were collected annually at 24 sites over a 6- or 8-year period (fish, 2003 to 2008; macroinvertebrates, 2001 to 2008). For this report, these data were first analyzed to determine the presence of temporal change in macroinvertebrate and fish community structure among years using nonparametric multivariate statistics. Where temporal change in the biological communities was found, these data were further analyzed using additional nonparametric multivariate techniques to determine which subset of selected streamflow, habitat, or water-chemistry variables best described site-specific changes in community structure relative to a gradient of urbanization. This study identified significant directional patterns of temporal change in macroinvertebrate and fish community structure at 15 of 24 sites in the Fountain Creek basin. At four of these sites, changes in environmental variables were significantly correlated with the concurrent temporal change identified in macroinvertebrate and fish community structure (Monument Creek above Woodmen Road at Colorado Springs, Colo.; Monument Creek at Bijou Street at Colorado Springs, Colo.; Bear Creek near Colorado Springs, Colo.; Fountain Creek at Security, Colo.). Combinations of environmental variables describing directional temporal change in the biota appeared to be site specific as no single variable dominated the results; however, substrate composition variables (percent substrate composition composed of sand, gravel, or cobble) collectively were present in 80 percent of the environmental variable subsets that were significantly correlated with temporal change in the macroinvertebrate and fish community structure. Other important environmental variables related to temporal change in the biological community structure included those describing channel form (streambank height) and streamflow (normalized annual mean daily flow, high flood-pulse count). Site-specific results from this study were derived from a relatively small number of observations (6 or 8 years of data); therefore, additional years of data may reveal other sites with temporal change in biological community structure, or could define stronger and more consistent linkages between environmental variables and observed temporal change. Likewise current variable subsets could become weaker. Nonetheless, there were several sites where temporal change was detected in this study that could not be explained by the available environmental variables studied herein. Modification of current data-collection activities may be necessary to better understand site-specific temporal relations between biological communities and environmental variables.

Analytical and biological variability in biomarker measurement in the Hispanic Community Health Study/Study of Latinos.

PubMed

Thyagarajan, Bharat; Howard, Annie Green; Durazo-Arvizu, Ramon; Eckfeldt, John H; Gellman, Marc D; Kim, Ryung S; Liu, Kiang; Mendez, Armando J; Penedo, Frank J; Talavera, Gregory A; Youngblood, Marston E; Zhao, Lihui; Sotres-Alvarez, Daniela

2016-12-01

Biomarker variability, which includes within-individual variability (CV I ), between-individual variability (CV G ) and methodological variability (CV P + A ) is an important determinant of our ability to detect biomarker-disease associations. Estimates of CV I and CV G may be population specific and little data exists on biomarker variability in diverse Hispanic populations. Hence, we evaluated all 3 components of biomarker variability in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) using repeat blood collections (n=58) and duplicate blood measurements (n=761-929 depending on the biomarker). We estimated the index of individuality (II) ((CV I +CV P + A )/CV G ) for 41 analytes and evaluated differences in the II across sexes and age groups. Biomarkers such as fasting glucose, triglycerides and ferritin had substantially higher inter-individual variability and lower II in HCHS/SOL as compared to the published literature. We also found significant sex-specific differences in the II for neutrophil count, platelet count, hemoglobin, % eosinophils and fasting glucose. The II for fasting insulin, post oral glucose tolerance test glucose and cystatin C was significantly higher among the 18-44y age group as compared to the 45+y age group. The implications of these findings for determining biomarker-disease associations in Hispanic populations need to be evaluated in future studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Demographic and Indication-Specific Characteristics Have Limited Association With Social Network Engagement: Evidence From 24,954 Members of Four Health Care Support Groups.

PubMed

van Mierlo, Trevor; Li, Xinlong; Hyatt, Douglas; Ching, Andrew T

2017-02-17

Digital health social networks (DHSNs) are widespread, and the consensus is that they contribute to wellness by offering social support and knowledge sharing. The success of a DHSN is based on the number of participants and their consistent creation of externalities through the generation of new content. To promote network growth, it would be helpful to identify characteristics of superusers or actors who create value by generating positive network externalities. The aim of the study was to investigate the feasibility of developing predictive models that identify potential superusers in real time. This study examined associations between posting behavior, 4 demographic variables, and 20 indication-specific variables. Data were extracted from the custom structured query language (SQL) databases of 4 digital health behavior change interventions with DHSNs. Of these, 2 were designed to assist in the treatment of addictions (problem drinking and smoking cessation), and 2 for mental health (depressive disorder, panic disorder). To analyze posting behavior, 10 models were developed, and negative binomial regressions were conducted to examine associations between number of posts, and demographic and indication-specific variables. The DHSNs varied in number of days active (3658-5210), number of registrants (5049-52,396), number of actors (1085-8452), and number of posts (16,231-521,997). In the sample, all 10 models had low R 2 values (.013-.086) with limited statistically significant demographic and indication-specific variables. Very few variables were associated with social network engagement. Although some variables were statistically significant, they did not appear to be practically significant. Based on the large number of study participants, variation in DHSN theme, and extensive time-period, we did not find strong evidence that demographic characteristics or indication severity sufficiently explain the variability in number of posts per actor. Researchers should investigate alternative models that identify superusers or other individuals who create social network externalities. ©Trevor van Mierlo, Xinlong Li, Douglas Hyatt, Andrew T Ching. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 17.02.2017.

A call to standardize preanalytic data elements for biospecimens.

PubMed

Robb, James A; Gulley, Margaret L; Fitzgibbons, Patrick L; Kennedy, Mary F; Cosentino, L Mark; Washington, Kay; Dash, Rajesh C; Branton, Philip A; Jewell, Scott D; Lapham, Rosanna L

2014-04-01

Biospecimens must have appropriate clinical annotation (data) to ensure optimal quality for both patient care and research. Clinical preanalytic variables are the focus of this study. To define the essential preanalytic variables (data fields) that should be attached to every collected biospecimen and to provide a complete list of such variables, along with their relative importance, which can vary, depending on downstream use, institutional needs, and information technology capabilities. The College of American Pathologists Diagnostic Intelligence and Health Information Technology Committee sponsored a Biorepository Working Group to develop a ranked list of the preanalytic variables for annotating biospecimens. Members of the working group were experts in anatomic, clinical, and molecular pathology; biobanking; medical informatics; and accreditation. Several members had experience with federal government programs, such as the National Cancer Institute's Biospecimens and Biorepository Branch and the National Cancer Institute's Community Cancer Center Program. Potential preanalytic variables were identified and ranked along with available supporting evidence, definitions, and potential negative effects if the variable was not attached to the biospecimen. Additional national and international stakeholders reviewed the draft manuscript. The ranked listing of 170 preanalytic variables produced can be used as a guide for site-specific implementation into patient care and/or research biorepository processes. Conclusions.-In our collective experience, it is often difficult to choose which of the many preanalytic variables to attach to any specific set of biospecimens used for patient care and/or research. The provided ranked list should aid in the selection of preanalytic variables for a given biospecimen collection.

The Mission Defines the Cycle: Turbojet, Turbofan and Variable Cycle Engines for High Speed Propulsion

DTIC Science & Technology

2010-09-01

RTO-EN-AVT-185 2 - 1 The Mission Defines the Cycle: Turbojet, Turbofan and Variable Cycle Engines for High Speed Propulsion Joachim Kurzke...following turbine parts 1 %. With T4=2000K the amounts of cooling air are 10% and 6% respectively. Burner pressure ratio is taken into account with 0.97 and...Figure 2 . Figure 3 shows specific thrust (i.e. thrust per unit of air flow) and specific fuel consumption SFC for three altitude / Mach number

Variability of human corticospinal excitability tracks the state of action preparation.

PubMed

Klein-Flügge, Miriam C; Nobbs, David; Pitcher, Julia B; Bestmann, Sven

2013-03-27

Task-evoked trial-by-trial variability is a ubiquitous property of neural responses, yet its functional role remains largely unclear. Recent work in nonhuman primates shows that the temporal structure of neural variability in several brain regions is task-related. For example, trial-by-trial variability in premotor cortex tracks motor preparation with increasingly consistent firing rates and thus a decline in variability before movement onset. However, whether noninvasive measures of the variability of population activity available from humans can similarly track the preparation of actions remains unknown. We tested this by using single-pulse transcranial magnetic stimulation (TMS) over primary motor cortex (M1) to measure corticospinal excitability (CSE) at different times during action preparation. First, we established the basic properties of intrinsic CSE variability at rest. Then, during the task, responses (left or right button presses) were either directly instructed (forced choice) or resulted from a value decision (choice). Before movement onset, we observed a temporally specific task-related decline in CSE variability contralateral to the responding hand. This decline was stronger in fast-response compared with slow-response trials, consistent with data in nonhuman primates. For the nonresponding hand, CSE variability also decreased, but only in choice trials, and earlier compared with the responding hand, possibly reflecting choice-specific suppression of unselected actions. These findings suggest that human CSE variability measured by TMS over M1 tracks the state of motor preparation, and may reflect the optimization of preparatory population activity. This provides novel avenues in humans to assess the dynamics of action preparation but also more complex processes, such as choice-to-action transformations.

Antisaccade performance of 1,273 men: effects of schizotypy, anxiety, and depression.

PubMed

Smyrnis, Nikolaos; Evdokimidis, Ioannis; Stefanis, Nicholas C; Avramopoulos, Dimitrios; Constantinidis, Theodoros S; Stavropoulos, Alexios; Stefanis, Costas N

2003-08-01

A total of 1,273 conscripts of the Greek Air Force performed antisaccades and completed self-reporting questionnaires measuring schizotypy and current state-dependent psychopathology. Only 1.0% of variability in antisaccade performance indices was related to psychometric scores in the population and could be attributed more to current state-dependent symptoms such as anxiety rather than to schizotypy. In contrast, a specific increase of error rate and response latency variability and a high correlation of these 2 variables was observed in a group with very high schizotypy scores. This effect was independent of anxiety and depression, suggesting that a specific group of psychosis-prone individuals has a characteristic deviance in antisaccade performance that is not present in the general population.

An estimator for the standard deviation of a natural frequency. II.

NASA Technical Reports Server (NTRS)

Schiff, A. J.; Bogdanoff, J. L.

1971-01-01

A method has been presented for estimating the variability of a system's natural frequencies arising from the variability of the system's parameters. The only information required to obtain the estimates is the member variability, in the form of second-order properties, and the natural frequencies and mode shapes of the mean system. It has also been established for the systems studied by means of Monte Carlo estimates that the specification of second-order properties is an adequate description of member variability.

Influence of lake surface area and total phosphorus on annual bluegill growth in small impoundments of central Georgia

USGS Publications Warehouse

Jennings, Cecil A.; Sundmark, Aaron P.

2017-01-01

The relationships between environmental variables and the growth rates of fishes are important and rapidly expanding topics in fisheries ecology. We used an informationtheoretic approach to evaluate the influence of lake surface area and total phosphorus on the age-specific growth rates of Lepomis macrochirus (Bluegill) in 6 small impoundments in central Georgia. We used model averaging to create composite models and determine the relative importance of the variables within each model. Results indicated that surface area was the most important factor in the models predicting growth of Bluegills aged 1–4 years; total phosphorus was also an important predictor for the same age-classes. These results suggest that managers can use water quality and lake morphometry variables to create predictive models specific to their waterbody or region to help develop lake-specific management plans that select for and optimize local-level habitat factors for enhancing Bluegill growth.

Technical variables in high-throughput miRNA expression profiling: much work remains to be done.

PubMed

Nelson, Peter T; Wang, Wang-Xia; Wilfred, Bernard R; Tang, Guiliang

2008-11-01

MicroRNA (miRNA) gene expression profiling has provided important insights into plant and animal biology. However, there has not been ample published work about pitfalls associated with technical parameters in miRNA gene expression profiling. One source of pertinent information about technical variables in gene expression profiling is the separate and more well-established literature regarding mRNA expression profiling. However, many aspects of miRNA biochemistry are unique. For example, the cellular processing and compartmentation of miRNAs, the differential stability of specific miRNAs, and aspects of global miRNA expression regulation require specific consideration. Additional possible sources of systematic bias in miRNA expression studies include the differential impact of pre-analytical variables, substrate specificity of nucleic acid processing enzymes used in labeling and amplification, and issues regarding new miRNA discovery and annotation. We conclude that greater focus on technical parameters is required to bolster the validity, reliability, and cultural credibility of miRNA gene expression profiling studies.

Genome-wide analysis of differential transcriptional and epigenetic variability across human immune cell types.

PubMed

Ecker, Simone; Chen, Lu; Pancaldi, Vera; Bagger, Frederik O; Fernández, José María; Carrillo de Santa Pau, Enrique; Juan, David; Mann, Alice L; Watt, Stephen; Casale, Francesco Paolo; Sidiropoulos, Nikos; Rapin, Nicolas; Merkel, Angelika; Stunnenberg, Hendrik G; Stegle, Oliver; Frontini, Mattia; Downes, Kate; Pastinen, Tomi; Kuijpers, Taco W; Rico, Daniel; Valencia, Alfonso; Beck, Stephan; Soranzo, Nicole; Paul, Dirk S

2017-01-26

A healthy immune system requires immune cells that adapt rapidly to environmental challenges. This phenotypic plasticity can be mediated by transcriptional and epigenetic variability. We apply a novel analytical approach to measure and compare transcriptional and epigenetic variability genome-wide across CD14 + CD16 - monocytes, CD66b + CD16 + neutrophils, and CD4 + CD45RA + naïve T cells from the same 125 healthy individuals. We discover substantially increased variability in neutrophils compared to monocytes and T cells. In neutrophils, genes with hypervariable expression are found to be implicated in key immune pathways and are associated with cellular properties and environmental exposure. We also observe increased sex-specific gene expression differences in neutrophils. Neutrophil-specific DNA methylation hypervariable sites are enriched at dynamic chromatin regions and active enhancers. Our data highlight the importance of transcriptional and epigenetic variability for the key role of neutrophils as the first responders to inflammatory stimuli. We provide a resource to enable further functional studies into the plasticity of immune cells, which can be accessed from: http://blueprint-dev.bioinfo.cnio.es/WP10/hypervariability .

ADPROCLUS: a graphical user interface for fitting additive profile clustering models to object by variable data matrices.

PubMed

Wilderjans, Tom F; Ceulemans, Eva; Van Mechelen, Iven; Depril, Dirk

2011-03-01

In many areas of psychology, one is interested in disclosing the underlying structural mechanisms that generated an object by variable data set. Often, based on theoretical or empirical arguments, it may be expected that these underlying mechanisms imply that the objects are grouped into clusters that are allowed to overlap (i.e., an object may belong to more than one cluster). In such cases, analyzing the data with Mirkin's additive profile clustering model may be appropriate. In this model: (1) each object may belong to no, one or several clusters, (2) there is a specific variable profile associated with each cluster, and (3) the scores of the objects on the variables can be reconstructed by adding the cluster-specific variable profiles of the clusters the object in question belongs to. Until now, however, no software program has been publicly available to perform an additive profile clustering analysis. For this purpose, in this article, the ADPROCLUS program, steered by a graphical user interface, is presented. We further illustrate its use by means of the analysis of a patient by symptom data matrix.

Biomarker progressions explain higher variability in stage-specific cognitive decline than baseline values in Alzheimer disease.

PubMed

Dodge, Hiroko H; Zhu, Jian; Harvey, Danielle; Saito, Naomi; Silbert, Lisa C; Kaye, Jeffrey A; Koeppe, Robert A; Albin, Roger L

2014-11-01

It is unknown which commonly used Alzheimer disease (AD) biomarker values-baseline or progression-best predict longitudinal cognitive decline. 526 subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI). ADNI composite memory and executive scores were the primary outcomes. Individual-specific slope of the longitudinal trajectory of each biomarker was first estimated. These estimates and observed baseline biomarker values were used as predictors of cognitive declines. Variability in cognitive declines explained by baseline biomarker values was compared with variability explained by biomarker progression values. About 40% of variability in memory and executive function declines was explained by ventricular volume progression among mild cognitive impairment patients. A total of 84% of memory and 65% of executive function declines were explained by fluorodeoxyglucose positron emission tomography (FDG-PET) score progression and ventricular volume progression, respectively, among AD patients. For most biomarkers, biomarker progressions explained higher variability in cognitive decline than biomarker baseline values. This has important implications for clinical trials targeted to modify AD biomarkers. Copyright © 2014 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

Climate change/variability science and adaptive strategies for state and regional transportation decision making.

DOT National Transportation Integrated Search

2010-04-01

The objective of this study was to generate a baseline understanding of current policy responses to climate : change/variability at the state and regional transportation-planning and -decision levels. Specifically, : researchers were interested in th...

Computational Integration of Human Genetic Data to Evaluate AOP-Specific Susceptibility

EPA Science Inventory

There is a need for approaches to efficiently evaluate human genetic variability and susceptibility related to environmental chemical exposure. Direct estimation of the genetic contribution to variability in susceptibility to environmental chemicals is only possible in special ca...

Black Male Labor Force Participation.

ERIC Educational Resources Information Center

Baer, Roger K.

This study attempts to test (via multiple regression analysis) hypothesized relationships between designated independent variables and age specific incidences of labor force participation for black male subpopulations in 54 Standard Metropolitan Statistical Areas. Leading independent variables tested include net migration, earnings, unemployment,…

Scenarios for Motivating the Learning of Variability: An Example in Finances

ERIC Educational Resources Information Center

Cordani, Lisbeth K.

2013-01-01

This article explores an example in finances in order to motivate the random variable learning to the very beginners in statistics. In addition, it offers a relationship between standard deviation and range in a very specific situation.

[Environmental and genetic variables related with alterations in language acquisition in early childhood].

PubMed

Moriano-Gutierrez, A; Colomer-Revuelta, J; Sanjuan, J; Carot-Sierra, J M

2017-01-01

A great deal of research has addressed problems in the correct acquisition of language, but with few overall conclusions. The reasons for this lie in the individual variability, the existence of different measures for assessing language and the fact that a complex network of genetic and environmental factors are involved in its development. To review the environmental and genetic variables that have been studied to date, in order to gain a better under-standing of the causes of specific language impairment and create new evidence that can help in the development of screening systems for the early detection of these disorders. The environmental variables related with poorer early child language development include male gender, low level of education of the mother, familial history of problems with language or psychiatric problems, perinatal problems and health problems in early childhood. Bilingualism seems to be a protective factor. Temperament and language are related. Within the genetic factors there are several specific genes associated with language, two of which have a greater influence on its physiological acquisition: FOXP2 and CNTNAP2. The other genes that are most related with specific language disorders are ATP2C2, CMIP, ROBO2, ZNF277 and NOP9. The key to comprehending the development of specific language disorders lies in reaching an understanding of the true role played by genes in the ontogenesis, in the regulation of the different developmental processes, and how this role is modulated by the environment.

Anthropometric and performance comparisons in professional baseball players.

PubMed

Hoffman, Jay R; Vazquez, Jose; Pichardo, Napoleon; Tenenbaum, Gershon

2009-11-01

This study compared anthropometric and performance variables in professional baseball players and examined the relationship between these variables and baseball-specific performance (i.e., home runs, total bases, slugging percentage, and stolen bases). During a 2-year period, 343 professional baseball players were assessed for height, weight, body composition, grip strength, vertical jump power, 10-yard sprint speed, and agility. Subject population consisted of players on the rosters of one of the minor league affiliates (Rookie, A, AA, AAA) or major league team (MLB). All testing occurred at the beginning of spring training. Players in Rookie and A were significantly (p < 0.05) leaner than players in MLB and AAA. These same players had significantly lower lean body mass than seen in MLB, AAA, and AA players. Greater grip strength (p < 0.05) was seen in MLB and AAA than in Rookie and A. Players in MLB were also faster (p < 0.05) than players in AA, A, and Rookie. Vertical jump power measures were greater (p < 0.05) in MLB than AA, A, and Rookie. Regression analysis revealed that performance measures accounted for 25-31% of the variance in baseball-specific power performance. Anthropometric measures failed to add any additional explanation to the variance in these baseball-specific performance variables. Results indicated that both anthropometric and performance variables differed between players of different levels of competition in professional baseball. Agility, speed, and lower-body power appeared to provide the greatest predictive power of baseball-specific performance.

Probe-specific mixed-model approach to detect copy number differences using multiplex ligation-dependent probe amplification (MLPA)

PubMed Central

González, Juan R; Carrasco, Josep L; Armengol, Lluís; Villatoro, Sergi; Jover, Lluís; Yasui, Yutaka; Estivill, Xavier

2008-01-01

Background MLPA method is a potentially useful semi-quantitative method to detect copy number alterations in targeted regions. In this paper, we propose a method for the normalization procedure based on a non-linear mixed-model, as well as a new approach for determining the statistical significance of altered probes based on linear mixed-model. This method establishes a threshold by using different tolerance intervals that accommodates the specific random error variability observed in each test sample. Results Through simulation studies we have shown that our proposed method outperforms two existing methods that are based on simple threshold rules or iterative regression. We have illustrated the method using a controlled MLPA assay in which targeted regions are variable in copy number in individuals suffering from different disorders such as Prader-Willi, DiGeorge or Autism showing the best performace. Conclusion Using the proposed mixed-model, we are able to determine thresholds to decide whether a region is altered. These threholds are specific for each individual, incorporating experimental variability, resulting in improved sensitivity and specificity as the examples with real data have revealed. PMID:18522760

Measuring performance in virtual reality phacoemulsification surgery

NASA Astrophysics Data System (ADS)

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

2008-02-01

We have developed a virtual reality (VR) simulator for phacoemulsification surgery. The current work aimed at developing a relative performance index that characterizes the performance of an individual trainee. We recorded measurements of 28 response variables during three iterated surgical sessions in 9 experienced cataract surgeons, separately for the sculpting phase and the evacuation phase of phacoemulsification surgery and compared their outcome to that of a reference group of naive trainees. We defined an individual overall performance index, an individual class specific performance index and an individual variable specific performance index. We found that on an average the experienced surgeons performed at a lower level than a reference group of naive trainees but that this was particularly attributed to a few surgeons. When their overall performance index was further analyzed as class specific performance index and variable specific performance index it was found that the low level performance was attributed to a behavior that is acceptable for an experienced surgeon but not for a naive trainee. It was concluded that relative performance indices should use a reference group that corresponds to the measured individual since the definition of optimal surgery may vary among trainee groups depending on their level of experience.

Country-Specific Effects of Climate Variability on Human Migration.

PubMed

Gray, Clark; Wise, Erika

2016-04-01

Involuntary human migration is among the social outcomes of greatest concern in the current era of global climate change. Responding to this concern, a growing number of studies have investigated the consequences of short to medium-term climate variability for human migration using demographic and econometric approaches. These studies have provided important insights, but at the same time have been significantly limited by lack of expertise in the use of climate data, access to cross-national data on migration, and attention to model specification. To address these limitations, we link data on internal and international migration over a 6-year period from 9,812 origin households in Kenya, Uganda, Nigeria, Burkina Faso and Senegal to high-resolution gridded climate data from both station and satellite sources. Analyses of these data using several plausible specifications reveal that climate variability has country-specific effects on migration: Migration tends to increase with temperature anomalies in Uganda, tends to decrease with temperature anomalies in Kenya and Burkina Faso, and shows no consistent relationship with temperature in Nigeria and Senegal. Consistent with previous studies, precipitation shows weak and inconsistent relationships with migration across countries. These results challenge generalizing narratives that foresee a consistent migratory response to climate change across the globe.

Variability in the American Society of Anesthesiologists (ASA) Physical Status (PS) Classification Scale

DTIC Science & Technology

2000-01-03

was altered by several variables (patient condition, planned surgical procedure, experience and skill of surgeon and anesthetist, and attention to...be developed. Variables in addition to the patient physical status ( experience of the surgeon, anesthetist, and hospital personnel) could be entered...specific surgery. Surgical risks include experience of the surgical team, the medical institution, elective versus emergent, availability of

A Framework for Categorizing Important Project Variables

NASA Technical Reports Server (NTRS)

Parsons, Vickie S.

2003-01-01

While substantial research has led to theories concerning the variables that affect project success, no universal set of such variables has been acknowledged as the standard. The identification of a specific set of controllable variables is needed to minimize project failure. Much has been hypothesized about the need to match project controls and management processes to individual projects in order to increase the chance for success. However, an accepted taxonomy for facilitating this matching process does not exist. This paper surveyed existing literature on classification of project variables. After an analysis of those proposals, a simplified categorization is offered to encourage further research.

Etiological Beliefs, Treatments, Stigmatizing Attitudes toward Schizophrenia. What Do Italians and Israelis Think?

PubMed

Mannarini, Stefania; Boffo, Marilisa; Rossi, Alessandro; Balottin, Laura

2017-01-01

Background: Although scientific research on the etiology of mental disorders has improved the knowledge of biogenetic and psychosocial aspects related to the onset of mental illness, stigmatizing attitudes and behaviors are still very prevalent and pose a significant social problem. Aim: The aim of this study was to deepen the knowledge of how attitudes toward people with mental illness are affected by specific personal beliefs and characteristics, such as culture and religion of the perceiver. More precisely, the main purpose is the definition of a structure of variables, namely perceived dangerousness, social closeness, and avoidance of the ill person, together with the beliefs about the best treatment to be undertaken and the sick person' gender, capable of describing the complexity of the stigma construct in particular as far as schizophrenia is concerned. Method: The study involved 305 university students, 183 from the University of Padua, Italy, and 122 from the University of Haifa, Israel. For the analyses, a latent class analysis (LCA) approach was chosen to identify a latent categorical structure accounting for the covariance between the observed variables. Such a latent structure was expected to be moderated by cultural background (Italy versus Israel) and religious beliefs, whereas causal beliefs, recommended treatment, dangerousness, social closeness, and public avoidance were the manifest variables, namely the observed indicators of the latent variable. Results: Two sets of results were obtained. First, the relevance of the manifest variables as indicators of the hypothesized latent variable was highlighted. Second, a two-latent-class categorical dimension represented by prejudicial attitudes, causal beliefs, and treatments concerning schizophrenia was found. Specifically, the differential effects of the two cultures and the religious beliefs on the latent structure and their relations highlighted the relevance of the observed variables as indicators of the expected latent variable. Conclusion: The present study contributes to the improvement of the understanding of how attitudes toward people with mental illness are affected by specific personal beliefs and characteristics of the perceiver. The definition of a structure of variables capable of describing the complexity of the stigma construct in particular as far as schizophrenia is concerned was achieved from a cross-cultural perspective.

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 pragmatic approach for mortality prediction after surgery in infective endocarditis: optimizing and refining EuroSCORE.

PubMed

Fernández-Hidalgo, N; Ferreria-González, I; Marsal, J R; Ribera, A; Aznar, M L; de Alarcón, A; García-Cabrera, E; Gálvez-Acebal, J; Sánchez-Espín, G; Reguera-Iglesias, J M; De La Torre-Lima, J; Lomas, J M; Hidalgo-Tenorio, C; Vallejo, N; Miranda, B; Santos-Ortega, A; Castro, M A; Tornos, P; García-Dorado, D; Almirante, B

2018-03-03

To simplify and optimize the ability of EuroSCORE I and II to predict early mortality after surgery for infective endocarditis (IE). Multicentre retrospective study (n = 775). Simplified scores, eliminating irrelevant variables, and new specific scores, adding specific IE variables, were created. The performance of the original, recalibrated and specific EuroSCOREs was assessed by Brier score, C-statistic and calibration plot in bootstrap samples. The Net Reclassification Index was quantified. Recalibrated scores including age, previous cardiac surgery, critical preoperative state, New York Heart Association >I, and emergent surgery (EuroSCORE I and II); renal failure and pulmonary hypertension (EuroSCORE I); and urgent surgery (EuroSCORE II) performed better than the original EuroSCOREs (Brier original and recalibrated: EuroSCORE I: 0.1770 and 0.1667; EuroSCORE II: 0.2307 and 0.1680). Performance improved with the addition of fistula, staphylococci and mitral location (EuroSCORE I and II) (Brier specific: EuroSCORE I 0.1587, EuroSCORE II 0.1592). Discrimination improved in specific models (C-statistic original, recalibrated and specific: EuroSCORE I: 0.7340, 0.7471 and 0.7728; EuroSCORE II: 0.7442, 0.7423 and 0.7700). Calibration improved in both EuroSCORE I models (intercept 0.295, slope 0.829 (original); intercept -0.094, slope 0.888 (recalibrated); intercept -0.059, slope 0.925 (specific)) but only in specific EuroSCORE II model (intercept 2.554, slope 1.114 (original); intercept -0.260, slope 0.703 (recalibrated); intercept -0.053, slope 0.930 (specific)). Net Reclassification Index was 5.1% and 20.3% for the specific EuroSCORE I and II CONCLUSIONS: The use of simplified EuroSCORE I and EuroSCORE II models in IE with the addition of specific variables may lead to simpler and more accurate models. Copyright © 2018 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

External quality-assurance results for the National Atmospheric Deposition Program / National Trends Network and Mercury Deposition Network, 2004

USGS Publications Warehouse

Wetherbee, Gregory A.; Latysh, Natalie E.; Greene, Shannon M.

2006-01-01

The U.S. Geological Survey (USGS) used five programs to provide external quality-assurance monitoring for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) and two programs to provide external quality-assurance monitoring for the NADP/Mercury Deposition Network (NADP/MDN) during 2004. An intersite-comparison program was used to estimate accuracy and precision of field-measured pH and specific-conductance. The variability and bias of NADP/NTN data attributed to field exposure, sample handling and shipping, and laboratory chemical analysis were estimated using the sample-handling evaluation (SHE), field-audit, and interlaboratory-comparison programs. Overall variability of NADP/NTN data was estimated using a collocated-sampler program. Variability and bias of NADP/MDN data attributed to field exposure, sample handling and shipping, and laboratory chemical analysis were estimated using a system-blank program and an interlaboratory-comparison program. In two intersite-comparison studies, approximately 89 percent of NADP/NTN site operators met the pH measurement accuracy goals, and 94.7 to 97.1 percent of NADP/NTN site operators met the accuracy goals for specific conductance. Field chemistry measurements were discontinued by NADP at the end of 2004. As a result, the USGS intersite-comparison program also was discontinued at the end of 2004. Variability and bias in NADP/NTN data due to sample handling and shipping were estimated from paired-sample concentration differences and specific conductance differences obtained for the SHE program. Median absolute errors (MAEs) equal to less than 3 percent were indicated for all measured analytes except potassium and hydrogen ion. Positive bias was indicated for most of the measured analytes except for calcium, hydrogen ion and specific conductance. Negative bias for hydrogen ion and specific conductance indicated loss of hydrogen ion and decreased specific conductance from contact of the sample with the collector bucket. Field-audit results for 2004 indicate dissolved analyte loss in more than one-half of NADP/NTN wet-deposition samples for all analytes except chloride. Concentrations of contaminants also were estimated from field-audit data. On the basis of 2004 field-audit results, at least 25 percent of the 2004 NADP/NTN concentrations for sodium, potassium, and chloride were lower than the maximum sodium, potassium, and chloride contamination likely to be found in 90 percent of the samples with 90-percent confidence. Variability and bias in NADP/NTN data attributed to chemical analysis by the NADP Central Analytical Laboratory (CAL) were comparable to the variability and bias estimated for other laboratories participating in the interlaboratory-comparison program for all analytes. Variability in NADP/NTN ammonium data evident in 2002-03 was reduced substantially during 2004. Sulfate, hydrogen-ion, and specific conductance data reported by CAL during 2004 were positively biased. A significant (a = 0.05) bias was identified for CAL sodium, potassium, ammonium, and nitrate data, but the absolute values of the median differences for these analytes were less than the method detection limits. No detections were reported for CAL analyses of deionized-water samples, indicating that contamination was not a problem for CAL. Control charts show that CAL data were within statistical control during at least 90 percent of 2004. Most 2004 CAL interlaboratory-comparison results for synthetic wet-deposition solutions were within ?10 percent of the most probable values (MPVs) for solution concentrations except for chloride, nitrate, sulfate, and specific conductance results from one sample in November and one specific conductance result in December. Overall variability of NADP/NTN wet-deposition measurements was estimated during water year 2004 by the median absolute errors for weekly wet-deposition sample concentrations and precipitation measurements for tw

Bilateral hegu acupoints have the same effect on the heart rate variability of the healthy subjects.

PubMed

Guangjun, Wang; Yuying, Tian; Shuyong, Jia; Wenting, Zhou; Weibo, Zhang

2014-01-01

Background. The specificity of acupuncture points (acupoints) is one of the key concepts in traditional acupuncture theory, but the question of whether there is adequate scientific evidence to prove or disprove specificity has been vigorously debated in recent years. Acupoint laterality is an important aspect of acupoint specificity. Data is particularly scarce regarding the laterality of the same channel, namesake acupoint located on opposite sides of the body. Our previous study results suggest that Neiguan acupoint (PC6) has the laterality. The aim of this study was to investigate whether Hegu (LI4) also has laterality from the perspective of heart rate variability. Methods. A total of twenty-eight healthy female volunteers were recruited for this study and were randomly separated into the group I (n = 14) and the group II (n = 14) according to the register order. In the group I, left LI4 was stimulated in the first epoch and the right LI4 was stimulated in the second epoch. In the group II, right LI4 was stimulated in the first epoch and left LI4 was stimulated in the second epoch. Electrocardiogram was recorded and heart rate variability was analyzed. Results. The results show that there were no significant differences of heart rate variablity between the group I and the group II in the time domain and in the frequency domain. Conclusions. Bilateral Hegu acupoints have the same effect on the heart rate variability of the healthy subjects.

Predictors of Full Enteral Feeding Achievement in Very Low Birth Weight Infants

PubMed Central

Corvaglia, Luigi; Fantini, Maria Pia; Aceti, Arianna; Gibertoni, Dino; Rucci, Paola; Baronciani, Dante; Faldella, Giacomo

2014-01-01

Background To elucidate the role of prenatal, neonatal and early postnatal variables in influencing the achievement of full enteral feeding (FEF) in very low birth weight (VLBW) infants and to determine whether neonatal intensive care units (NICUs) differ in this outcome. Methods Population-based retrospective cohort study using data on 1,864 VLBW infants drawn from the “Emilia-Romagna Perinatal Network” Registry from 2004 to 2009. The outcome of interest was time to FEF achievement. Eleven prenatal, neonatal and early postnatal variables and the study NICUs were selected as potential predictors of time to FEF. Parametric survival analysis was used to model time to FEF as a function of the predictors. Marginal effects were used to obtain adjusted estimates of median time to FEF for specific subgroups of infants. Results Lower gestational age, exclusive formula feeding, higher CRIB II score, maternal hypertension, cesarean delivery, SGA and PDA predicted delayed FEF. NICUs proved to be heterogeneous in terms of FEF achievement. Newborns with PDA had a 4.2 days longer predicted median time to FEF compared to those without PDA; newborns exclusively formula-fed had a 1.4 days longer time to FEF compared to those fed human milk. Conclusions The results of our study suggest that time to FEF is influenced by clinical variables and NICU-specific practices. Knowledge of the variables associated with delayed/earlier FEF achievement could help in improving specific aspects of routine clinical management of VLBW infants and to reduce practice variability. PMID:24647523

Management Styles, Mediating Variables, and Stress among HRD Professionals.

ERIC Educational Resources Information Center

Lind, Susan L.; Otte, Fred L.

1994-01-01

Data from 355 valid responses from 1,000 human resource professionals showed that specific variables predicted stress according to the management style of respondents' managers (authoritative, benevolent, consultative, participative). Self-esteem, locus of control, and Type A behavior were consistent predictors. (SK)

Field variability and vulnerability index to identify precision agriculture opportunity

USDA-ARS?s Scientific Manuscript database

Innovations in precision agriculture (PA) have created opportunities to achieve a greater understanding of within-field variability. However, PA adoption has been hindered due to uncertainty about field-specific performance and return on investment. Uncertainty could be better addressed by analyzing...

Predictor variable resolution governs modeled soil types

USDA-ARS?s Scientific Manuscript database

Soil mapping identifies different soil types by compressing a unique suite of spatial patterns and processes across multiple spatial scales. It can be quite difficult to quantify spatial patterns of soil properties with remotely sensed predictor variables. More specifically, matching the right scale...

Variability of cement-treated layers in MDOT road projects.

DOT National Transportation Integrated Search

2011-12-01

The Mississippi Department of Transportation revised the specifications for cement-treated : bases between the 1990 and 2004 editions of Mississippi Standard Specifications for Road and Bridge : Construction. The required compressive strength o...

Measuring motivation in schizophrenia: Is a general state of motivation necessary for task-specific motivation?

PubMed Central

Choi, Jimmy; Choi, Kee-Hong; Reddy, Felice; Fiszdon, Joanna M.

2014-01-01

Despite the important role of motivation in rehabilitation and functional outcomes in schizophrenia, to date, there has been little emphasis on how motivation is assessed. This is important, since different measures may tap potentially discrete motivational constructs, which in turn may have very different associations to important outcomes. In the current study, we used baseline data from 71 schizophrenia spectrum outpatients enrolled in a rehabilitation program to examine the relationship between task-specific motivation, as measured by the Intrinsic Motivation Inventory (IMI), and a more general state of volition/initiation, as measured by the three item Quality of Life (QLS) motivation index. We also examined the relationship of these motivation measures to demographic, clinical and functional variables relevant to rehabilitation outcomes. The two motivation measures were not correlated, and participants with low general state motivation exhibited a full range of task-specific motivation. Only the QLS motivation index correlated with variables relevant to rehabilitation outcomes. The lack of associations between QLS motivation index and IMI subscales suggests that constructs tapped by these measures may be divergent in schizophrenia, and specifically that task-specific intrinsic motivation is not contingent on a general state of motivation. That is, even in individuals with a general low motivational state (i.e. amotivation), interventions aimed at increasing task-specific motivation may still be effective. Moreover, the pattern of interrelationships between the QLS motivation index and variables relevant to psychosocial rehabilitation supports its use in treatment outcome studies. PMID:24529609

The Structural Model of Spirituality and Psychological Well-Being for Pregnancy-Specific Stress.

PubMed

Dolatian, Mahrokh; Mahmoodi, Zohreh; Dilgony, Taibeh; Shams, Jamal; Zaeri, Farid

2017-12-01

Women experience different types of stress in their lifetime. The present study was conducted to examine the structural model of spirituality and psychological well-being for pregnancy-specific stress. The present descriptive correlational study was conducted on 450 pregnant Iranian women (150 women from each trimester) in Dehdasht city in 2015. Data were collected using the personal-social questionnaire, the pregnancy-specific stress questionnaire, the spirituality questionnaire and the psychological well-being questionnaire and were then analyzed in SPSS-16 and Lisrel-8.8 for carrying out a path analysis. The fit indices of the model indicate the good fit and high compatibility of the model and rational relationships between the variables (GFI = 0.94, NFI = 0.85, CFI = 0.94 and RMSEA = 0.048). Of the variables that affected pregnancy-specific stress through both paths, spirituality had a positive effect (B = 0.11) and the personal-social variable a negative effect (B = -0.37). Psychological well-being affected pregnancy-specific stress negatively and directly and through one path only (B = -0.59). The results obtained through the model confirm the effect of spirituality and psychological well-being in reducing pregnancy-specific stress. Given that handling stress has a major role in the quality of daily life in pregnant women, stress management skills are recommended to be promoted among pregnant women so as to mitigate stress and its negative consequences.

Occurrence of and Sequence Variation among F-Specific RNA Bacteriophage Subgroups in Feces and Wastewater of Urban and Animal Origins

PubMed Central

Hartard, C.; Rivet, R.; Banas, S.

2015-01-01

F-specific RNA bacteriophages (FRNAPH) have been widely studied as tools for evaluating fecal or viral pollution in water. It has also been proposed that they can be used to differentiate human from animal fecal contamination. While FRNAPH subgroup I (FRNAPH-I) and FRNAPH-IV are often associated with animal pollution, FRNAPH-II and -III prevail in human wastewater. However, this distribution is not absolute, and variable survival rates in these subgroups lead to misinterpretation of the original distribution. In this context, we studied FRNAPH distribution in urban wastewater and animal feces/wastewater. To increase the specificity, we partially sequenced the genomes of phages of urban and animal origins. The persistence of the genomes and infectivity were also studied, over time in wastewater and during treatment, for each subgroup. FRNAPH-I genome sequences did not show any specific urban or animal clusters to allow development of molecular tools for differentiation. They were the most resistant and as such may be used as fecal or viral indicators. FRNAPH-II's low prevalence and low sequence variability in animal stools, combined with specific clusters formed by urban strains, allowed differentiation between urban and animal pollution by using a specific reverse transcription-PCR (RT-PCR) method. The subgroup's resistance over time was comparable to that of FRNAPH-I, but its surface properties allowed higher elimination rates during activated-sludge treatment. FRNAPH-III's low sequence variability in animal wastewater and specific cluster formation by urban strains also allowed differentiation by using a specific RT-PCR method. Nevertheless, its low resistance restricted it to being used only for recent urban pollution detection. FRNAPH-IV was too rare to be used. PMID:26162878

Occurrence of and Sequence Variation among F-Specific RNA Bacteriophage Subgroups in Feces and Wastewater of Urban and Animal Origins.

PubMed

Hartard, C; Rivet, R; Banas, S; Gantzer, C

2015-09-01

F-specific RNA bacteriophages (FRNAPH) have been widely studied as tools for evaluating fecal or viral pollution in water. It has also been proposed that they can be used to differentiate human from animal fecal contamination. While FRNAPH subgroup I (FRNAPH-I) and FRNAPH-IV are often associated with animal pollution, FRNAPH-II and -III prevail in human wastewater. However, this distribution is not absolute, and variable survival rates in these subgroups lead to misinterpretation of the original distribution. In this context, we studied FRNAPH distribution in urban wastewater and animal feces/wastewater. To increase the specificity, we partially sequenced the genomes of phages of urban and animal origins. The persistence of the genomes and infectivity were also studied, over time in wastewater and during treatment, for each subgroup. FRNAPH-I genome sequences did not show any specific urban or animal clusters to allow development of molecular tools for differentiation. They were the most resistant and as such may be used as fecal or viral indicators. FRNAPH-II's low prevalence and low sequence variability in animal stools, combined with specific clusters formed by urban strains, allowed differentiation between urban and animal pollution by using a specific reverse transcription-PCR (RT-PCR) method. The subgroup's resistance over time was comparable to that of FRNAPH-I, but its surface properties allowed higher elimination rates during activated-sludge treatment. FRNAPH-III's low sequence variability in animal wastewater and specific cluster formation by urban strains also allowed differentiation by using a specific RT-PCR method. Nevertheless, its low resistance restricted it to being used only for recent urban pollution detection. FRNAPH-IV was too rare to be used. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

The effects of basic fitness parameters on the implementation of specific military activities.

PubMed

Sporiš, Goran; Harasin, Dražen; Baić, Mario; Krističević, Tomislav; Krakan, Ivan; Milanović, Zoran; Cular, Dražen; Bagarić-Krakan, Lucija

2014-12-01

The aim of this study was to determine whether basic fitness parameters have the impact on the specific military activity such as walking 18 km with 25 kg of load. The members of Croatian Armed Forces (30 soldiers) were tested before the beginning of the training program. The study has included variables for the assessment of muscular endurance: push-ups in 2 minutes, sit-ups in 2 minutes, maximum number of pull-ups before dropping from the bar, bench press with 70% of body weight-max number of repetitions, max number of squats for 60 seconds, then the variables for the assessment of aerobic capacity: the 3200m run and relative oxygen uptake using the direct method of measurement on a treadmill as well as the variable for the assessment of body fat (body fat %). As the criterion variable, it was used the 18 km walking with 25 kg of load. The results of the regression analysis have shown statistically significant relation of predictor variables with the criterion variable. The two variables, 3200m run and RVO2 had a significant Beta coefficient. Based on the obtained results it could be concluded that great cardio-respiratory endurance has a much larger impact on the walking length of 18 km with a load of 25 kg than other fitness parameters.

Input-variable sensitivity assessment for sediment transport relations

NASA Astrophysics Data System (ADS)

Fernández, Roberto; Garcia, Marcelo H.

2017-09-01

A methodology to assess input-variable sensitivity for sediment transport relations is presented. The Mean Value First Order Second Moment Method (MVFOSM) is applied to two bed load transport equations showing that it may be used to rank all input variables in terms of how their specific variance affects the overall variance of the sediment transport estimation. In sites where data are scarce or nonexistent, the results obtained may be used to (i) determine what variables would have the largest impact when estimating sediment loads in the absence of field observations and (ii) design field campaigns to specifically measure those variables for which a given transport equation is most sensitive; in sites where data are readily available, the results would allow quantifying the effect that the variance associated with each input variable has on the variance of the sediment transport estimates. An application of the method to two transport relations using data from a tropical mountain river in Costa Rica is implemented to exemplify the potential of the method in places where input data are limited. Results are compared against Monte Carlo simulations to assess the reliability of the method and validate its results. For both of the sediment transport relations used in the sensitivity analysis, accurate knowledge of sediment size was found to have more impact on sediment transport predictions than precise knowledge of other input variables such as channel slope and flow discharge.

Electronic medical record integration with a database for adult congenital heart disease: Early experience and progress in automating multicenter data collection.

PubMed

Broberg, Craig S; Mitchell, Julie; Rehel, Silven; Grant, Andrew; Gianola, Ann; Beninato, Peter; Winter, Christiane; Verstappen, Amy; Valente, Anne Marie; Weiss, Joseph; Zaidi, Ali; Earing, Michael G; Cook, Stephen; Daniels, Curt; Webb, Gary; Khairy, Paul; Marelli, Ariane; Gurvitz, Michelle Z; Sahn, David J

2015-10-01

The adoption of electronic health records (EHR) has created an opportunity for multicenter data collection, yet the feasibility and reliability of this methodology is unknown. The aim of this study was to integrate EHR data into a homogeneous central repository specifically addressing the field of adult congenital heart disease (ACHD). Target data variables were proposed and prioritized by consensus of investigators at five target ACHD programs. Database analysts determined which variables were available within their institutions' EHR and stratified their accessibility, and results were compared between centers. Data for patients seen in a single calendar year were extracted to a uniform database and subsequently consolidated. From 415 proposed target variables, only 28 were available in discrete formats at all centers. For variables of highest priority, 16/28 (57%) were available at all four sites, but only 11% for those of high priority. Integration was neither simple nor straightforward. Coding schemes in use for congenital heart diagnoses varied and would require additional user input for accurate mapping. There was considerable variability in procedure reporting formats and medication schemes, often with center-specific modifications. Despite the challenges, the final acquisition included limited data on 2161 patients, and allowed for population analysis of race/ethnicity, defect complexity, and body morphometrics. Large-scale multicenter automated data acquisition from EHRs is feasible yet challenging. Obstacles stem from variability in data formats, coding schemes, and adoption of non-standard lists within each EHR. The success of large-scale multicenter ACHD research will require institution-specific data integration efforts. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Countermovement jump height: gender and sport-specific differences in the force-time variables.

PubMed

Laffaye, Guillaume; Wagner, Phillip P; Tombleson, Tom I L

2014-04-01

The goal of this study was to assess (a) the eccentric rate of force development, the concentric force, and selected time variables on vertical performance during countermovement jump, (b) the existence of gender differences in these variables, and (c) the sport-specific differences. The sample was composed of 189 males and 84 females, all elite athletes involved in college and professional sports (primarily football, basketball, baseball, and volleyball). The subjects performed a series of 6 countermovement jumps on a force plate (500 Hz). Average eccentric rate of force development (ECC-RFD), total time (TIME), eccentric time (ECC-T), Ratio between eccentric and total time (ECC-T:T) and average force (CON-F) were extracted from force-time curves and the vertical jumping performance, measured by impulse momentum. Results show that CON-F (r = 0.57; p < 0.001) and ECC-RFD (r = 0.52, p < 0.001) are strongly correlated with the jump height (JH), whereas the time variables are slightly and negatively correlated (r = -0.21-0.23, p < 0.01). Force variables differ between both sexes (p < 0.01), whereas time variables did not differ, showing a similar temporal structure. The best way to jump high is to increase CON-F and ECC-RFD thus minimizing the ECC-T. Principal component analysis (PCA) accounted for 76.8% of the JH variance and revealed that JH is predicted by a temporal and a force component. Furthermore, the PCA comparison made among athletes revealed sport-specific signatures: volleyball players revealed a temporal-prevailing profile, a weak-force with large ECC-T:T for basketball players and explosive and powerful profiles for football and baseball players.

Combining measurements from three anatomical areas for glaucoma diagnosis using Fourier-domain optical coherence tomography.

PubMed

Loewen, Nils A; Zhang, Xinbo; Tan, Ou; Francis, Brian A; Greenfield, David S; Schuman, Joel S; Varma, Rohit; Huang, David

2015-09-01

To improve the diagnostic power for glaucoma by combining measurements of peripapillary nerve fibre layer (NFL), macular ganglion cell complex (GCC) and disc variables obtained with Fourier-domain optical coherence tomography (FD-OCT) into the glaucoma structural diagnostic index (GSDI). In this observational, cross-sectional study of subjects from the Advanced Imaging of Glaucoma Study, GCC and NFL of healthy and perimetrical glaucoma subjects from four major academic referral centres of the Advanced Imaging of Glaucoma Study were mapped with the RTVue FD-OCT. Global loss volume and focal loss volume parameters were defined using NFL and GCC normative reference maps. Optimal weights for NFL, GCC and disc variables were combined using multivariate logistic regression to build the GSDI. Glaucoma severity was classified using the Enhanced Glaucoma Staging System (GSS2). Diagnostic accuracy was assessed by sensitivity, specificity and the area under the receiver operator characteristic curve (AUC). We analysed 118 normal eyes of 60 subjects, 236 matched eyes of 166 subjects with perimetrical glaucoma, and 105 eyes from a healthy reference group of 61 subjects. The GSDI included composite overall thickness and focal loss volume with weighted NFL and GCC components, as well as the vertical cup-to-disc ratio. The AUC of 0.922 from leave-one-out cross validation was better than the best component variable alone (p=0.047). The partial AUC in the high specificity region was also better (p=0.01), with a sensitivity of 69% at 99% specificity, and a sensitivity of 80.3% at 95% specificity. For GSS2 stages 3-5 the sensitivity was 98% at 99% specificity, and 100% at 95% specificity. Combining structural measurements of GCC, NFL and disc variables from FD-OCT created a GSDI that improved the accuracy for glaucoma diagnosis. NCT01314326. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Identification of the need for home visiting nurse: development of a new assessment tool

PubMed Central

Taguchi, Atsuko; Nagata, Satoko; Naruse, Takashi; Kuwahara, Yuki; Yamaguchi, Takuhiro; Murashima, Sachiyo

2014-01-01

Objective To develop a Home Visiting Nursing Service Need Assessment Form (HVNS-NAF) to standardize the decision about the need for home visiting nursing service. Methods The sample consisted of older adults who had received coordinated services by care managers. We defined the need for home visiting nursing service by elderly individuals as the decision of the need by a care manager so that the elderly can continue to live independently. Explanatory variables included demographic factors, medical procedure, severity of illness, and caregiver variables. Multiple logistic regression was carried out after univariate analyses to decide the variables to include and the weight of each variable in the HVNS-NAF. We then calculated the sensitivity and specificity of each cutoff value, and defined the score with the highest sensitivity and specificity as the cutoff value. Results Nineteen items were included in the final HVNS-NAF. When the cutoff value was 2 points, the sensitivity was 77.0%, specificity 68.5%, and positive predictive value 56.8%. Conclusions HVNS-NAF is the first validated standard based on characteristics of elderly clients who required home visiting nursing service. Using the HVNS-NAF may result in reducing the unmet need for home visiting nursing service and preventing hospitalization. PMID:24665229

A Systematic Review of the Effect of Cognitive Strategies on Strength Performance.

PubMed

Tod, David; Edwards, Christian; McGuigan, Mike; Lovell, Geoff

2015-11-01

Researchers have tested the beliefs of sportspeople and sports medicine specialists that cognitive strategies influence strength performance. Few investigators have synthesised the literature. The specific objectives were to review evidence regarding (a) the cognitive strategy-strength performance relationship; (b) participant skill level as a moderator; and (c) cognitive, motivational, biomechanical/physiological, and emotional mediators. Studies were sourced via electronic databases, reference lists of retrieved articles, and manual searches of relevant journals. Studies had to be randomised or counterbalanced experiments with a control group or condition, repeated measures, and a quality control score above 0.5 (out of 1). Cognitive strategies included goal setting, imagery, self-talk, preparatory arousal, and free choice. Dependent variables included maximal strength, local muscular endurance, or muscular power. Globally, cognitive strategies were reliability associated with increased strength performance (results ranged from 61 to 65 %). Results were mixed when examining the effects of specific strategies on particular dependent variables, although no intervention had an overall negative influence. Indeterminate relationships emerged regarding hypothesised mediators (except cognitive variables) and participant skill level as a moderator. Although cognitive strategies influence strength performance, there are knowledge gaps regarding specific types of strength, especially muscular power. Cognitive variables, such as concentration, show promise as possible mediators.

The Usefulness of Clinical-Practice-Based Laboratory Data in Facilitating the Diagnosis of Dengue Illness

PubMed Central

Liu, Jien-Wei; Lee, Ing-Kit; Wang, Lin; Chen, Rong-Fu; Yang, Kuender D.

2013-01-01

Alertness to dengue and making a timely diagnosis is extremely important in the treatment of dengue and containment of dengue epidemics. We evaluated the complementary role of clinical-practice-based laboratory data in facilitating suspicion/diagnosis of dengue. One hundred overall dengue (57 dengue fever [DF] and 43 dengue hemorrhagic fever [DHF]) cases and another 100 nondengue cases (78 viral infections other than dengue, 6 bacterial sepsis, and 16 miscellaneous diseases) were analyzed. We separately compared individual laboratory variables (platelet count [PC] , prothrombin time [PT], activated partial thromboplastin time [APTT], alanine aminotransferase [ALT], and aspartate aminotransferase [AST]) and varied combined variables of DF and/or DHF cases with the corresponding ones of nondengue cases. The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) in the diagnosis of DF and/or DHF were measured based on these laboratory variables. While trade-off between sensitivity and specificity, and/or suboptimal PPV/NPV was found at measurements using these variables, prolonged APTT + normal PT + PC < 100 × 109 cells/L had a favorable sensitivity, specificity, PPV, and NPV in diagnosis of DF and/or DHF. In conclusion, these data suggested that prolonged APTT + normal PT + PC < 100 × 109 cells/L is useful in evaluating the likelihood of DF and/or DHF. PMID:24455678

Comparative jet wake structure and swimming performance of salps.

PubMed

Sutherland, Kelly R; Madin, Laurence P

2010-09-01

Salps are barrel-shaped marine invertebrates that swim by jet propulsion. Morphological variations among species and life-cycle stages are accompanied by differences in swimming mode. The goal of this investigation was to compare propulsive jet wakes and swimming performance variables among morphologically distinct salp species (Pegea confoederata, Weelia (Salpa) cylindrica, Cyclosalpa sp.) and relate swimming patterns to ecological function. Using a combination of in situ dye visualization and particle image velocimetry (PIV) measurements, we describe properties of the jet wake and swimming performance variables including thrust, drag and propulsive efficiency. Locomotion by all species investigated was achieved via vortex ring propulsion. The slow-swimming P. confoederata produced the highest weight-specific thrust (T=53 N kg(-1)) and swam with the highest whole-cycle propulsive efficiency (eta(wc)=55%). The fast-swimming W. cylindrica had the most streamlined body shape but produced an intermediate weight-specific thrust (T=30 N kg(-1)) and swam with an intermediate whole-cycle propulsive efficiency (eta(wc)=52%). Weak swimming performance variables in the slow-swimming C. affinis, including the lowest weight-specific thrust (T=25 N kg(-1)) and lowest whole-cycle propulsive efficiency (eta(wc)=47%), may be compensated by low energetic requirements. Swimming performance variables are considered in the context of ecological roles and evolutionary relationships.

Computer Optimization of Biodegradable Nanoparticles Fabricated by Dispersion Polymerization.

PubMed

Akala, Emmanuel O; Adesina, Simeon; Ogunwuyi, Oluwaseun

2015-12-22

Quality by design (QbD) in the pharmaceutical industry involves designing and developing drug formulations and manufacturing processes which ensure predefined drug product specifications. QbD helps to understand how process and formulation variables affect product characteristics and subsequent optimization of these variables vis-à-vis final specifications. Statistical design of experiments (DoE) identifies important parameters in a pharmaceutical dosage form design followed by optimizing the parameters with respect to certain specifications. DoE establishes in mathematical form the relationships between critical process parameters together with critical material attributes and critical quality attributes. We focused on the fabrication of biodegradable nanoparticles by dispersion polymerization. Aided by a statistical software, d-optimal mixture design was used to vary the components (crosslinker, initiator, stabilizer, and macromonomers) to obtain twenty nanoparticle formulations (PLLA-based nanoparticles) and thirty formulations (poly-ɛ-caprolactone-based nanoparticles). Scheffe polynomial models were generated to predict particle size (nm), zeta potential, and yield (%) as functions of the composition of the formulations. Simultaneous optimizations were carried out on the response variables. Solutions were returned from simultaneous optimization of the response variables for component combinations to (1) minimize nanoparticle size; (2) maximize the surface negative zeta potential; and (3) maximize percent yield to make the nanoparticle fabrication an economic proposition.

Predictors of competitive achievement among pubescent synchronized swimmers: an analysis of the solo-figure competition.

PubMed

Peric, M; Cavar, M; Zenic, N; Sekulic, D; Sajber, D

2014-02-01

This study examined the applicability of sport-specific fitness tests (SSTs), anthropometrics, and respiratory parameters in predicting competitive results among pubescent synchronized swimmers. A total of 25 synchronized swimmers (16-17 years; 166.2 ± 5.4 cm; and 58.4 ± 4.3 kg) volunteered for this study. The independent variables were body mass, body height, Body Mass Index (BMI), body fat percentage (BF%), lean body mass percentage, respiratory variables, and four SSTs (two specific power tests plus one aerobic- and one anaerobic-endurance test). The dependent variable was competitive achievement in the solo figure competition. The reliability analyses, Pearson's correlation coefficient and forward stepwise regression were calculated. The SSTs were reliable for testing fitness status among pubescent synchronized swimmers. The forward stepwise regression retained two SSTs, BF% and forced vital capacity (FVC, relative for age and stature) in a set of predictors of competitive achievement. Significant Beta coefficients are found for aerobic-endurance, SST and FVC. The sport-specific measure of aerobic endurance and FVC appropriately predicted competitive achievement with regard to the figures used in the competition when competitive results (the dependent variable) were obtained. Athletes and coaches should be aware of the probable negative influence of very low body fat levels on competitive achievement.

Moment-to-Moment BOLD Signal Variability Reflects Regional Changes in Neural Flexibility across the Lifespan.

PubMed

Nomi, Jason S; Bolt, Taylor S; Ezie, C E Chiemeka; Uddin, Lucina Q; Heller, Aaron S

2017-05-31

Variability of neuronal responses is thought to underlie flexible and optimal brain function. Because previous work investigating BOLD signal variability has been conducted within task-based fMRI contexts on adults and older individuals, very little is currently known regarding regional changes in spontaneous BOLD signal variability in the human brain across the lifespan. The current study used resting-state fMRI data from a large sample of male and female human participants covering a wide age range (6-85 years) across two different fMRI acquisition parameters (TR = 0.645 and 1.4 s). Variability in brain regions including a key node of the salience network (anterior insula) increased linearly across the lifespan across datasets. In contrast, variability in most other large-scale networks decreased linearly over the lifespan. These results demonstrate unique lifespan trajectories of BOLD variability related to specific regions of the brain and add to a growing literature demonstrating the importance of identifying normative trajectories of functional brain maturation. SIGNIFICANCE STATEMENT Although brain signal variability has traditionally been considered a source of unwanted noise, recent work demonstrates that variability in brain signals during task performance is related to brain maturation in old age as well as individual differences in behavioral performance. The current results demonstrate that intrinsic fluctuations in resting-state variability exhibit unique maturation trajectories in specific brain regions and systems, particularly those supporting salience detection. These results have implications for investigations of brain development and aging, as well as interpretations of brain function underlying behavioral changes across the lifespan. Copyright © 2017 the authors 0270-6474/17/375539-10$15.00/0.

Teachers' Occupation-Specific Work-Family Conflict

ERIC Educational Resources Information Center

Cinamon, Rachel Gali; Rich, Yisrael; Westman, Mina

2007-01-01

To expand work-family conflict (WFC) research to specific occupations, this study investigated how work and family generic and occupation-specific stressors and support variables related to family interfering with work (F [right arrow] W) and work interfering with family (W [right arrow] F) among 230 Israeli high school teachers. Further expanding…

Using a Participatory Culture-Specific Model to Increase the Effectiveness of Social Justice Courses in School Psychology

ERIC Educational Resources Information Center

Graybill, Emily C.; Varjas, Kris; Meyers, Joel; Greenberg, Daphne; Roach, Andrew T.

2013-01-01

The Participatory Culture-Specific Model of Course Development (PCSMCD), adapted from the Participatory Culture-Specific Intervention Model, is a proposed framework to address challenges to social justice education by addressing the following four course variables: instructor characteristics, instructor experiences, student characteristics, and…

Variability in the American Society of Anesthesiologists (ASA) Physical Status (PS) Classifcation Scale

DTIC Science & Technology

1999-10-01

instrument, and was deemed unsuitable because it was altered by several variables (patient condition, planned surgical procedure, experience and skill...index of anesthetic risk could be developed. Variables in addition to the patient physical status ( experience of the surgeon, anesthetist, and hospital...and other concurrent illnesses), but also by risk inherent to the specific surgery. Surgical risks include experience of the surgical team, the

Determinants of virtual water flows in the Mediterranean.

PubMed

Fracasso, Andrea; Sartori, Martina; Schiavo, Stefano

2016-02-01

The aim of the paper is to investigate the main determinants of the bilateral virtual water (water used in the production of a commodity or service) flows associated with international trade in agricultural goods across the Mediterranean basin. We consider the bilateral gross flows of virtual water in the area and study what export-specific and import-specific factors are significantly associated with virtual water flows. We follow a sequential approach. Through a gravity model of trade, we obtain a "refined" version of the variable we aim to explain, one that is free of the amount of flows due to pair-specific factors affecting bilateral trade flows and that fully reflects the impact of country-specific determinants of virtual water trade. A number of country-specific potential explanatory variables, ranging from water endowments to trade barriers, from per capita GDP to irrigation prices, is presented and tested. To identify the variables that help to explain the bilateral flows of virtual water, we adopt a model selection procedure based on model averaging. Our findings confirm one of the main controversial results in the literature: larger water endowments do not necessarily lead to a larger 'export' of virtual water, as one could expect. We also find some evidence that higher water irrigation prices reduce (increase) virtual water 'exports' ('imports'). Copyright © 2015 Elsevier B.V. All rights reserved.

Bacterial community assembly in activated sludge: mapping beta diversity across environmental variables.

PubMed

Isazadeh, Siavash; Jauffur, Shameem; Frigon, Dominic

2016-12-01

Effect of ecological variables on community assembly of heterotrophic bacteria at eight full-scale and two pilot-scale activated sludge wastewater treatment plants (AS-WWTPs) were explored by pyrosequencing of 16S rRNA gene amplicons. In total, 39 samples covering a range of abiotic factors spread over space and time were analyzed. A core bacterial community of 24 families detected in at least six of the eight AS-WWTPs was defined. In addition to the core families, plant-specific families (observed at <50% AS-WWTPs) were found to be also important in the community structure. Observed beta diversity was partitioned with respect to ecological variables. Specifically, the following variables were considered: influent wastewater characteristics, season (winter vs. summer), process operations (conventional, oxidation ditch, and sequence batch reactor), reactor sizes (pilot-scale vs. full-scale reactors), chemical stresses defined by ozonation of return activated sludge, interannual variation, and geographical locations. Among the assessed variables, influent wastewater characteristics and geographical locations contributed more in explaining the differences between AS-WWTP bacterial communities with a maximum of approximately 26% of the observed variations. Partitioning of beta diversity is necessary to interpret the inherent variability in microbial community assembly and identify the driving forces at play in engineered microbial ecosystem. © 2016 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Lower limb kinematics during treadmill walking after space flight: implications for gaze stabilization

NASA Technical Reports Server (NTRS)

McDonald, P. V.; Basdogan, C.; Bloomberg, J. J.; Layne, C. S.

1996-01-01

We examined the lower limb joint kinematics observed during pre- and postflight treadmill walking performed by seven subjects from three Space Shuttle flights flown between March 1992 and February 1994. Basic temporal characteristics of the gait patterns, such as stride time and duty cycle, showed no significant changes after flight. Evaluation of phaseplane variability across the gait cycle suggests that postflight treadmill walking is more variable than preflight, but the response throughout the course of a cycle is joint dependent and, furthermore, the changes are subject dependent. However, analysis of the phaseplane variability at the specific locomotor events of heel strike and toe off indicated statistically significant postflight increases in knee variability at the moment of heel strike and significantly higher postflight hip joint variability at the moment of toe off. Nevertheless, the observation of component-specific variability was not sufficient to cause a change in the overall lower limb joint system stability, since there was no significant change in an index used to evaluate this at both toe off and heel strike. The implications of the observed lower limb kinematics for head and gaze control during locomotion are discussed in light of a hypothesized change in the energy attenuation capacity of the musculoskeletal system in adapting to weightlessness.

Lower limb kinematics during treadmill walking after space flight: implications for gaze stabilization.

PubMed

McDonald, P V; Basdogan, C; Bloomberg, J J; Layne, C S

1996-11-01

We examined the lower limb joint kinematics observed during pre- and postflight treadmill walking performed by seven subjects from three Space Shuttle flights flown between March 1992 and February 1994. Basic temporal characteristics of the gait patterns, such as stride time and duty cycle, showed no significant changes after flight. Evaluation of phaseplane variability across the gait cycle suggests that postflight treadmill walking is more variable than preflight, but the response throughout the course of a cycle is joint dependent and, furthermore, the changes are subject dependent. However, analysis of the phaseplane variability at the specific locomotor events of heel strike and toe off indicated statistically significant postflight increases in knee variability at the moment of heel strike and significantly higher postflight hip joint variability at the moment of toe off. Nevertheless, the observation of component-specific variability was not sufficient to cause a change in the overall lower limb joint system stability, since there was no significant change in an index used to evaluate this at both toe off and heel strike. The implications of the observed lower limb kinematics for head and gaze control during locomotion are discussed in light of a hypothesized change in the energy attenuation capacity of the musculoskeletal system in adapting to weightlessness.

Systems effects on family planning innovativeness.

PubMed

Lee, S B

1983-12-01

Data from Korea were used to explore the importance of community level variables in explaining family planning adoption at the individual level. An open system concept was applied, assuming that individual family planning behavior is influenced by both environmental and individual factors. The environmental factors were measured at the village level and designated as community characteristics. The dimension of communication network variables was introduced. Each individual was characterized in terms of the degree of her involvement in family planning communication with others in her village. It was assumed that the nature of the communication network linking individuals with each other effects family planning adoption at the individual level. Specific objectives were to determine 1) the relative importance of the specific independent variables in explaining family planning adoption and 2) the relative importance of the community level variables in comparison with the individual level variables in explaining family planning adoption at the individual level. The data were originally gathered in a 1973 research project on Korea's mothers' clubs. 1047 respondents were interviewed, comprising all married women in 25 sample villages having mothers' clubs. The dependent variable was family planning adoption behavior, defined as current use of any of the modern methods of family planning. The independent variables were defined at 3 levels: individual, community, and at a level intermediate between them involving communication links between individuals. More of the individual level independent variables were significantly correlated with the dependent variables than the community level variables. Among those variables with statistically significant correlations, the correlation coefficients were consistently higher for the individual level than for the community level variables. More of the variance in the dependent variable was explained by individual level than by community level variables. Community level variables accounted for only about 2.5% of the total variance in the dependent variable, in marked contrast to the result showing individual level variables accounting for as much as 19% of the total variance. When both individual and community level variables were entered into a multiple correlation analysis, a multiple correlation coefficient of .4714 was obtained together they explained about 20% of the total variance. The 2 communication network variables--connectedness and integrativeness--were correlated with the dependent variable at much higher levels than most of the individual or community level variables. Connectedness accounted for the greatest amount of the total variance. The communication network variables as a group explained as much of the total variance in the dependent variable as the individual level variables and greatly more that the community level variables.

Nonintellective Variables and Nontraditional College Students: A Domain-Based Investigation of Academic Achievement

ERIC Educational Resources Information Center

Warden, David N; Myers, Charlsie A.

2017-01-01

The relationship between domain-specific nonintellective variables and academic achievement among nontraditional students was explored to address uninvestigated factors and clarify distinctions between nontraditional and traditional student achievement. College students (nontraditional n = 72, traditional n = 67) completed an online survey…

A Theoretical Approach for Selecting Elementary School Environmental Variables.

ERIC Educational Resources Information Center

Sinclair, Robert L.

To determine specific environmental variables of the elementary school is the purpose of this study. Stable characteristics of intelligence and achievement were selected because they were considered useful for generating salient environmental counterparts likely to exist in elementary institutions. Achievement motivation, language development, and…

Variable & Recode Definitions - SEER Documentation

Cancer.gov

Resources that define variables and provide documentation for reporting using SEER and related datasets. Choose from SEER coding and staging manuals plus instructions for recoding behavior, site, stage, cause of death, insurance, and several additional topics. Also guidance on months survived, calculating Hispanic mortality, and site-specific surgery.

Production of biodiesel from Jatropha curcas L. oil catalyzed by SO₄²⁻/ZrO₂ catalyst: effect of interaction between process variables.

PubMed

Yee, Kian Fei; Lee, Keat Teong; Ceccato, Riccardo; Abdullah, Ahmad Zuhairi

2011-03-01

This study reports the conversion of Jatrophacurcas L. oil to biodiesel catalyzed by sulfated zirconia loaded on alumina catalyst using response surface methodology (RSM), specifically to study the effect of interaction between process variables on the yield of biodiesel. The transesterification process variables studied were reaction temperature, reaction duration, molar ratio of methanol to oil and catalyst loading. Results from this study revealed that individual as well as interaction between variables significantly affect the yield of biodiesel. With this information, it was found that 4h of reaction at 150°C, methanol to oil molar ratio of 9.88 mol/mol and 7.61 wt.% for catalyst loading gave an optimum biodiesel yield of 90.32 wt.%. The fuel properties of Jatropha biodiesel were characterized and it indeed met the specification for biodiesel according to ASTM D6751. Copyright © 2010 Elsevier Ltd. All rights reserved.

Variability of Actinobacteria, a minor component of rumen microflora.

PubMed

Suľák, M; Sikorová, L; Jankuvová, J; Javorský, P; Pristaš, P

2012-07-01

Actinobacteria (Actinomycetes) are a significant and interesting group of gram-positive bacteria. They are regular, though infrequent, members of the microbial life in the rumen and represent up to 3 % of total rumen bacteria; there is considerable lack of information about ecology and biology of rumen actinobacteria. During the characterization of variability of rumen treponemas using non-cultivation approach, we also noted the variability of rumen actinobacteria. By using Treponema-specific primers a specific 16S rRNA gene library was prepared from cow and sheep rumen total DNA. About 10 % of recombinant clones contained actinobacteria-like sequences. Phylogenetic analyses of 11 clones obtained showed the high variability of actinobacteria in the ruminant digestive system. While some sequences are nearly identical to known sequences of actinobacteria, we detected completely new clusters of actinobacteria-like sequences, representing probably new, as yet undiscovered, group of rumen Actinobacteria. Further research will be necessary for understanding their nature and functions in the rumen.

Programming with non-heap memory in the real time specification for Java

NASA Technical Reports Server (NTRS)

Bollella, G.; Canham, T.; Carson, V.; Champlin, V.; Dvorak, D.; Giovannoni, B.; Indictor, M.; Meyer, K.; Reinholtz, A.; Murray, K.

2003-01-01

The Real-Time Specification for Java (RTSJ) provides facilities for deterministic, real-time execution in a language that is otherwise subject to variable latencies in memory allocation and garbage collection.

The Importance of Postural Control in Relation to Technical Abilities in Small-Sided Soccer Games

PubMed Central

Edis, Çağlar; Vurgun, Hikmet

2016-01-01

Abstract Making assessments regarding postural control and balance is very important for injury prevention in soccer. However, there has been no study that has associated postural control variables with branch-specific technical properties in a game. The aim of the present study was to determine the relationships between variables designating postural control levels and technical performance variables in different (1:1, 2:2 and 3:3) small-sided games (SSGs). Sixteen trained male amateur soccer players volunteered to take part in the study (age 17.2 ± 1.02 years, body height 176.25 ± 0.07 m, body mass 67.67 ± 13.27 kg). Following familiarization sessions, postural control was evaluated using one-leg and both-leg quiet-stance positions by measuring postural sway with a Tekscan HR Mat™ in anterior–posterior and medial–lateral directions. Later, 1:1, 2:2 and 3:3 SSGs were performed at two-day intervals and the technical variables specified for each game were analyzed. A Spearman’s rank-order correlation analysis demonstrated the relationship between postural control and soccer-specific technical variables in 1:1 (r-values ranging from 0.582 to 0.776), 2:2 (rvalues ranging from 0.511 to 0.740) and 3:3 (r-values ranging from 0.502 to 0.834) SSGs. In addition, a Wilcoxon signed rank test revealed differences between SSGs in terms of several variables. The results of the study showed that higher postural control levels are among the important variables that affect success in the performance of technical skills under rival pressure and suddenly changing conditions. Therefore, it is recommended that in addition to its use for injury prevention purposes, balance training should be conducted to improve branch-specific technical skills and to increase the levels of their successful performance in a game. PMID:28149410

The Importance of Postural Control in Relation to Technical Abilities in Small-Sided Soccer Games.

PubMed

Edis, Çağlar; Vural, Faik; Vurgun, Hikmet

2016-12-01

Making assessments regarding postural control and balance is very important for injury prevention in soccer. However, there has been no study that has associated postural control variables with branch-specific technical properties in a game. The aim of the present study was to determine the relationships between variables designating postural control levels and technical performance variables in different (1:1, 2:2 and 3:3) small-sided games (SSGs). Sixteen trained male amateur soccer players volunteered to take part in the study (age 17.2 ± 1.02 years, body height 176.25 ± 0.07 m, body mass 67.67 ± 13.27 kg). Following familiarization sessions, postural control was evaluated using one-leg and both-leg quiet-stance positions by measuring postural sway with a Tekscan HR Mat™ in anterior-posterior and medial-lateral directions. Later, 1:1, 2:2 and 3:3 SSGs were performed at two-day intervals and the technical variables specified for each game were analyzed. A Spearman's rank-order correlation analysis demonstrated the relationship between postural control and soccer-specific technical variables in 1:1 (r-values ranging from 0.582 to 0.776), 2:2 (rvalues ranging from 0.511 to 0.740) and 3:3 (r-values ranging from 0.502 to 0.834) SSGs. In addition, a Wilcoxon signed rank test revealed differences between SSGs in terms of several variables. The results of the study showed that higher postural control levels are among the important variables that affect success in the performance of technical skills under rival pressure and suddenly changing conditions. Therefore, it is recommended that in addition to its use for injury prevention purposes, balance training should be conducted to improve branch-specific technical skills and to increase the levels of their successful performance in a game.

Ventricular repolarization variability for hypoglycemia detection.

PubMed

Ling, Steve; Nguyen, H T

2011-01-01

Hypoglycemia is the most acute and common complication of Type 1 diabetes and is a limiting factor in a glycemic management of diabetes. In this paper, two main contributions are presented; firstly, ventricular repolarization variabilities are introduced for hypoglycemia detection, and secondly, a swarm-based support vector machine (SVM) algorithm with the inputs of the repolarization variabilities is developed to detect hypoglycemia. By using the algorithm and including several repolarization variabilities as inputs, the best hypoglycemia detection performance is found with sensitivity and specificity of 82.14% and 60.19%, respectively.

Accounting for substitution and spatial heterogeneity in a labelled choice experiment.

PubMed

Lizin, S; Brouwer, R; Liekens, I; Broeckx, S

2016-10-01

Many environmental valuation studies using stated preferences techniques are single-site studies that ignore essential spatial aspects, including possible substitution effects. In this paper substitution effects are captured explicitly in the design of a labelled choice experiment and the inclusion of different distance variables in the choice model specification. We test the effect of spatial heterogeneity on welfare estimates and transfer errors for minor and major river restoration works, and the transferability of river specific utility functions, accounting for key variables such as site visitation, spatial clustering and income. River specific utility functions appear to be transferable, resulting in low transfer errors. However, ignoring spatial heterogeneity increases transfer errors. Copyright © 2016 Elsevier Ltd. All rights reserved.

Gaia DR2 documentation Chapter 7: Variability

NASA Astrophysics Data System (ADS)

Eyer, L.; Guy, L.; Distefano, E.; Clementini, G.; Mowlavi, N.; Rimoldini, L.; Roelens, M.; Audard, M.; Holl, B.; Lanzafame, A.; Lebzelter, T.; Lecoeur-Taïbi, I.; Molnár, L.; Ripepi, V.; Sarro, L.; Jevardat de Fombelle, G.; Nienartowicz, K.; De Ridder, J.; Juhász, Á.; Molinaro, R.; Plachy, E.; Regibo, S.

2018-04-01

This chapter of the Gaia DR2 documentation describes the models and methods used on the 22 months of data to produce the Gaia variable star results for Gaia DR2. The variability processing and analysis was based mostly on the calibrated G and integrated BP and RP photometry. The variability analysis approach to the Gaia data has been described in Eyer et al. (2017), and the Gaia DR2 results are presented in Holl et al. (2018). Detailed methods on specific topics will be published in a number of separate articles. Variability behaviour in the colour magnitude diagram is presented in Gaia Collaboration et al. (2018c).

Kinematic constraints associated with the acquisition of overarm throwing part II: upper extremity actions.

PubMed

Stodden, David F; Langendorfer, Stephen J; Fleisig, Glenn S; Andrews, James R

2006-12-01

The purposes of this study were to: (a) examine the differences within 11 specific kinematic variables and an outcome measure (ball velocity) associated with component developmental levels of humerus and forearm action (Roberton & Halverson, 1984), and (b) if the differences in kinematic variables were significantly associated with the differences in component levels, determine potential kinematic constraints associated with skilled throwing acquisition. Significant differences among component levels in five of six humerus kinematic variables (p <.01) and all five forearm kinematic variables (p < .01) were identified using multivariate analysis of variance. These kinematic variables represent potential control parameters and, therefore, constraints on overarm throwing acquisition.

Tree-, stand- and site-specific controls on landscape-scale patterns of transpiration

NASA Astrophysics Data System (ADS)

Kathrin Hassler, Sibylle; Weiler, Markus; Blume, Theresa

2018-01-01

Transpiration is a key process in the hydrological cycle, and a sound understanding and quantification of transpiration and its spatial variability is essential for management decisions as well as for improving the parameterisation and evaluation of hydrological and soil-vegetation-atmosphere transfer models. For individual trees, transpiration is commonly estimated by measuring sap flow. Besides evaporative demand and water availability, tree-specific characteristics such as species, size or social status control sap flow amounts of individual trees. Within forest stands, properties such as species composition, basal area or stand density additionally affect sap flow, for example via competition mechanisms. Finally, sap flow patterns might also be influenced by landscape-scale characteristics such as geology and soils, slope position or aspect because they affect water and energy availability; however, little is known about the dynamic interplay of these controls.We studied the relative importance of various tree-, stand- and site-specific characteristics with multiple linear regression models to explain the variability of sap velocity measurements in 61 beech and oak trees, located at 24 sites across a 290 km2 catchment in Luxembourg. For each of 132 consecutive days of the growing season of 2014 we modelled the daily sap velocity and derived sap flow patterns of these 61 trees, and we determined the importance of the different controls.Results indicate that a combination of mainly tree- and site-specific factors controls sap velocity patterns in the landscape, namely tree species, tree diameter, geology and aspect. For sap flow we included only the stand- and site-specific predictors in the models to ensure variable independence. Of those, geology and aspect were most important. Compared to these predictors, spatial variability of atmospheric demand and soil moisture explains only a small fraction of the variability in the daily datasets. However, the temporal dynamics of the explanatory power of the tree-specific characteristics, especially species, are correlated to the temporal dynamics of potential evaporation. We conclude that transpiration estimates on the landscape scale would benefit from not only consideration of hydro-meteorological drivers, but also tree, stand and site characteristics in order to improve the spatial and temporal representation of transpiration for hydrological and soil-vegetation-atmosphere transfer models.

Construction of an environmental quality index for public health research

PubMed Central

2014-01-01

Background A more comprehensive estimate of environmental quality would improve our understanding of the relationship between environmental conditions and human health. An environmental quality index (EQI) for all counties in the U.S. was developed. Methods The EQI was developed in four parts: domain identification; data source acquisition; variable construction; and data reduction. Five environmental domains (air, water, land, built and sociodemographic) were recognized. Within each domain, data sources were identified; each was temporally (years 2000–2005) and geographically (county) restricted. Variables were constructed for each domain and assessed for missingness, collinearity, and normality. Domain-specific data reduction was accomplished using principal components analysis (PCA), resulting in domain-specific indices. Domain-specific indices were then combined into an overall EQI using PCA. In each PCA procedure, the first principal component was retained. Both domain-specific indices and overall EQI were stratified by four rural–urban continuum codes (RUCC). Higher values for each index were set to correspond to areas with poorer environmental quality. Results Concentrations of included variables differed across rural–urban strata, as did within-domain variable loadings, and domain index loadings for the EQI. In general, higher values of the air and sociodemographic indices were found in the more metropolitan areas and the most thinly populated areas have the lowest values of each of the domain indices. The less-urbanized counties (RUCC 3) demonstrated the greatest heterogeneity and range of EQI scores (−4.76, 3.57) while the thinly populated strata (RUCC 4) contained counties with the most positive scores (EQI score ranges from −5.86, 2.52). Conclusion The EQI holds promise for improving our characterization of the overall environment for public health. The EQI describes the non-residential ambient county-level conditions to which residents are exposed and domain-specific EQI loadings indicate which of the environmental domains account for the largest portion of the variability in the EQI environment. The EQI was constructed for all counties in the United States, incorporating a variety of data to provide a broad picture of environmental conditions. We undertook a reproducible approach that primarily utilized publically-available data sources. PMID:24886426

Relationship between cotton yield and soil electrical conductivity, topography, and landsat imagery

USDA-ARS?s Scientific Manuscript database

Understanding spatial and temporal variability in crop yield is a prerequisite to implementing site-specific management of crop inputs. Apparent soil electrical conductivity (ECa), soil brightness, and topography are easily obtained data that can explain yield variability. The objectives of this stu...

10 CFR 50.36 - Technical specifications.

Code of Federal Regulations, 2013 CFR

2013-01-01

... nuclear reactors are limits upon important process variables that are found to be necessary to reasonably... Commission terminates the license for the reactor, except for nuclear power reactors licensed under § 50.21(b... for nuclear reactors are settings for automatic protective devices related to those variables having...

10 CFR 50.36 - Technical specifications.

Code of Federal Regulations, 2014 CFR

2014-01-01

... nuclear reactors are limits upon important process variables that are found to be necessary to reasonably... Commission terminates the license for the reactor, except for nuclear power reactors licensed under § 50.21(b... for nuclear reactors are settings for automatic protective devices related to those variables having...

10 CFR 50.36 - Technical specifications.

Code of Federal Regulations, 2012 CFR

2012-01-01

... nuclear reactors are limits upon important process variables that are found to be necessary to reasonably... Commission terminates the license for the reactor, except for nuclear power reactors licensed under § 50.21(b... for nuclear reactors are settings for automatic protective devices related to those variables having...

Interannual Variation in Phytoplankton Primary Production at a Global Scale

NASA Technical Reports Server (NTRS)

Rousseaux, Cecile Severine; Gregg, Watson W.

2013-01-01

We used the NASA Ocean Biogeochemical Model (NOBM) combined with remote sensing data via assimilation to evaluate the contribution of four phytoplankton groups to the total primary production. First, we assessed the contribution of each phytoplankton groups to the total primary production at a global scale for the period 1998-2011. Globally, diatoms contributed the most to the total phytoplankton production ((is)approximately 50%, the equivalent of 20 PgC·y1). Coccolithophores and chlorophytes each contributed approximately 20% ((is) approximately 7 PgC·y1) of the total primary production and cyanobacteria represented about 10% ((is) approximately 4 PgC·y1) of the total primary production. Primary production by diatoms was highest in the high latitudes ((is) greater than 40 deg) and in major upwelling systems (Equatorial Pacific and Benguela system). We then assessed interannual variability of this group-specific primary production over the period 1998-2011. Globally the annual relative contribution of each phytoplankton groups to the total primary production varied by maximum 4% (1-2 PgC·y1). We assessed the effects of climate variability on group-specific primary production using global (i.e., Multivariate El Niño Index, MEI) and "regional" climate indices (e.g., Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO)). Most interannual variability occurred in the Equatorial Pacific and was associated with climate variability as indicated by significant correlation (p (is) less than 0.05) between the MEI and the group-specific primary production from all groups except coccolithophores. In the Atlantic, climate variability as indicated by NAO was significantly correlated to the primary production of 2 out of the 4 groups in the North Central Atlantic (diatoms/cyanobacteria) and in the North Atlantic (chlorophytes and coccolithophores). We found that climate variability as indicated by SAM had only a limited effect on group-specific primary production in the Southern Ocean. These results provide a modeling and data assimilation perspective to phytoplankton partitioning of primary production and contribute to our understanding of the dynamics of the carbon cycle in the oceans at a global scale.

Validation of a Cochlear Implant Patient-Specific Model of the Voltage Distribution in a Clinical Setting

PubMed Central

Nogueira, Waldo; Schurzig, Daniel; Büchner, Andreas; Penninger, Richard T.; Würfel, Waldemar

2016-01-01

Cochlear Implants (CIs) are medical implantable devices that can restore the sense of hearing in people with profound hearing loss. Clinical trials assessing speech intelligibility in CI users have found large intersubject variability. One possibility to explain the variability is the individual differences in the interface created between electrodes of the CI and the auditory nerve. In order to understand the variability, models of the voltage distribution of the electrically stimulated cochlea may be useful. With this purpose in mind, we developed a parametric model that can be adapted to each CI user based on landmarks from individual cone beam computed tomography (CBCT) scans of the cochlea before and after implantation. The conductivity values of each cochlea compartment as well as the weighting factors of different grounding modes have also been parameterized. Simulations were performed modeling the cochlea and electrode positions of 12 CI users. Three models were compared with different levels of detail: a homogeneous model (HM), a non-patient-specific model (NPSM), and a patient-specific model (PSM). The model simulations were compared with voltage distribution measurements obtained from the backward telemetry of the 12 CI users. Results show that the PSM produces the lowest error when predicting individual voltage distributions. Given a patient-specific geometry and electrode positions, we show an example on how to optimize the parameters of the model and how to couple it to an auditory nerve model. The model here presented may help to understand speech performance variability and support the development of new sound coding strategies for CIs. PMID:27933290

High Power Light Gas Helicon Plasma Source For VASMIR

NASA Technical Reports Server (NTRS)

Squire, J. P.; Chang-Diaz, F. R.; Glover, T. W.; Jacobson, V. T.; McCaskill, G. E.; Winter, D. S.; Baity, F. W.; Carter, M. D.; Goulding, R. H.

2004-01-01

The VASIMR space propulsion development effort relies on a high power (greater than 10kW) helicon source to produce a dense flowing plasma (H, D and He) target for ion cyclotron resonance (ICR) acceleration of the ions. Subsequent expansion in an expanding magnetic field (magnetic nozzle) converts ion lunetic energy to directed momentum. This plasma source must have critical features to enable an effective propulsion device. First, it must ionize most of the input neutral flux of gas, thus producing a plasma stream with a high degree of ionization for application of ICR power. This avoids propellant waste and potential power losses due to charge exchange. Next, the plasma stream must flow into a region of high magnetic field (approximately 0.5 T) for efficient ICR acceleration. Third, the ratio of input power to plasma flux must be low, providing an energy per ion-electron pair approaching 100 eV. Lastly, the source must be robust and capable of very long life-times (years). In our helicon experiment (VX-10) we have measured a ratio of input gas to plasma flux near 100%. The plasma flows from the helicon region (B approximately 0.1 T) into a region with a peak magnetic field of 0.8 T. The energy input per ion-electron pair has been measured at 300 plus or minus 100 eV. Recent results at Oak Ridge National Laboratory (ORNL) show an enhanced efficiency mode of operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter and operates up to 3.5 kW of input power. An upgrade to a power level of 10 kW is underway. Much of our recent work has been with a Boswell double-saddle antenna design. We are also converting the antenna design to a helical type. With these modifications, we anticipate an improvement in the ionization efficiency. This paper presents the results from scaling the helicon in the VX-10 device from 3.5 to 10 kW. We also compare the operation with a double-saddle to a helical antenna design. Finally, we discuss modeling of these configurations using ORNL's EMIR code.

Treatment of specific phobia in older adults

PubMed Central

Pachana, Nancy A; Woodward, Rana M; Byrne, Gerard JA

2007-01-01

Phobias are common in later life, yet treatment research in this population remains scant. The efficacy of exposure therapy, in combination with other Cognitive-Behavioral Therapy (CBT) components, in the treatment of specific phobia with a middle and older aged sample was examined. Sixteen adults aged 45–68 with DSM-IV diagnosis of a specific phobia received a manualized intervention over ten weeks, and were compared with a control group. Results indicated significant time effects in the treatment group for the primary outcome variables of phobic severity and avoidance as well as secondary outcome variables including depression and anxiety. Symptom presence and severity also significantly declined in the treatment group. No significant changes in state anxiety were noted across the treatment period. Such results provide support for the efficacy of exposure combined with CBT treatment for specific phobia in middle to older aged adults. PMID:18044196

Variability in functional brain networks predicts expertise during action observation.

PubMed

Amoruso, Lucía; Ibáñez, Agustín; Fonseca, Bruno; Gadea, Sebastián; Sedeño, Lucas; Sigman, Mariano; García, Adolfo M; Fraiman, Ricardo; Fraiman, Daniel

2017-02-01

Observing an action performed by another individual activates, in the observer, similar circuits as those involved in the actual execution of that action. This activation is modulated by prior experience; indeed, sustained training in a particular motor domain leads to structural and functional changes in critical brain areas. Here, we capitalized on a novel graph-theory approach to electroencephalographic data (Fraiman et al., 2016) to test whether variability in functional brain networks implicated in Tango observation can discriminate between groups differing in their level of expertise. We found that experts and beginners significantly differed in the functional organization of task-relevant networks. Specifically, networks in expert Tango dancers exhibited less variability and a more robust functional architecture. Notably, these expertise-dependent effects were captured within networks derived from electrophysiological brain activity recorded in a very short time window (2s). In brief, variability in the organization of task-related networks seems to be a highly sensitive indicator of long-lasting training effects. This finding opens new methodological and theoretical windows to explore the impact of domain-specific expertise on brain plasticity, while highlighting variability as a fruitful measure in neuroimaging research. Copyright © 2016 Elsevier Inc. All rights reserved.

A cross-linguistic data bank for oral picture naming in Dutch, English, German, French, Italian, Russian, Spanish, and Swedish (PEDOI).

PubMed

Kremin, Helgard; Akhutina, Tanya; Basso, Anna; Davidoff, Jules; De Wilde, Martine; Kitzing, Peter; Lorenz, Antje; Perrier, Danièle; van der Sandt-Koenderman, Mieke; Vendrell, Josep; Weniger, Dorothea; Apt, Pia; Arabia, Catherine; De Bleser, Ria; Cohen, Henri; Corbineau, Mathilde; Dolivet, Marie-Christine; Hirsh, Kathi; Lehoux, Emilie; Metz-Lutz, Mari Noëlle; Montañes, Patricia; Plagne, Stéphanie; Polonskaya, Natalya; Sirois, Mélanie; Stachowiak, Franz; Sweeney, Trione; Vish-Brink, Evy

2003-11-01

The well established effect of word frequency on adult's picture naming performance is now called into question. This is particularly true for variables which are correlated with frequency, as is the case of age of word acquisition. Since the work of [Carrol and White, 1973] there is growing agreement among researchers to confer an important role in lexical access to this variable. Indeed, it has been shown ( [Hodgson and Ellis, 1998]) that for normal English-speaking adults only the variables 'age-of-acquisition' and 'name agreement' are independent predictors of naming success among the various variables considered. However, when brain-damaged subjects with and without degenerative pathologies are studied, word frequency and word length as well as concept familiarity all give significant effects ( [Hirsh and Funnell, 1995]; [Lambon Ralph et al., 1998]; [Nickels and Howard, 1995]). Finally, it has been suggested that the production of specific error types may be related to such variables. According to [Nickels and Howard, 1994] the production of semantic errors is specifically affected by 'imageability' and in the recent study by [Kremin et al., 2001] 'age of acquisition' predicts (frank) word finding difficulties.

Analysis of Lower Body Kinematic and Kinetic: Differences Between Age and Handicap in Golfers of Various Ages and Skill Levels

NASA Astrophysics Data System (ADS)

Smilensky, Alexander

The purpose of this thesis was to provide a preliminary analysis of lower body golf swing biomechanics. Fourteen golfers of various ages and handicaps performed 10 swings off a tee with their driver. This study focused on a number of dependent variables including lead knee joint flexion angles, internal/external rotations, valgus/varus angles, as well as ground reaction forces normalized to body weight (%BW), X-Factor angle and club head velocity. Dependent variables were analyzed at four specifically defined events (start, initiation of downswing, contact and swing termination). Simple linear regressions were performed using age and handicap as independent variables to see if patterns could be determined at any of the events. No significant trends or results were reported within our sample. An analysis of variance (ANOVA) was then used to examine the effect of event on specific dependent variables. A number of differences were reported within each of the variables across the four events. This study hoped to provide a more comprehensive understanding of the movement patterns occurring at the lower body with special focus on the lead knee.

Structural Equation Models in a Redundancy Analysis Framework With Covariates.

PubMed

Lovaglio, Pietro Giorgio; Vittadini, Giorgio

2014-01-01

A recent method to specify and fit structural equation modeling in the Redundancy Analysis framework based on so-called Extended Redundancy Analysis (ERA) has been proposed in the literature. In this approach, the relationships between the observed exogenous variables and the observed endogenous variables are moderated by the presence of unobservable composites, estimated as linear combinations of exogenous variables. However, in the presence of direct effects linking exogenous and endogenous variables, or concomitant indicators, the composite scores are estimated by ignoring the presence of the specified direct effects. To fit structural equation models, we propose a new specification and estimation method, called Generalized Redundancy Analysis (GRA), allowing us to specify and fit a variety of relationships among composites, endogenous variables, and external covariates. The proposed methodology extends the ERA method, using a more suitable specification and estimation algorithm, by allowing for covariates that affect endogenous indicators indirectly through the composites and/or directly. To illustrate the advantages of GRA over ERA we propose a simulation study of small samples. Moreover, we propose an application aimed at estimating the impact of formal human capital on the initial earnings of graduates of an Italian university, utilizing a structural model consistent with well-established economic theory.

Do diagnosis-related groups appropriately explain variations in costs and length of stay of hip replacement? A comparative assessment of DRG systems across 10 European countries.

PubMed

Geissler, Alexander; Scheller-Kreinsen, David; Quentin, Wilm

2012-08-01

This paper assesses the variations in costs and length of stay for hip replacement cases in Austria, England, Estonia, Finland, France, Germany, Ireland, Poland, Spain and Sweden and examines the ability of national diagnosis-related group (DRG) systems to explain the variation in resource use against a set of patient characteristic and treatment specific variables. In total, 195,810 cases clustered in 712 hospitals were analyzed using OLS fixed effects models for cost data (n=125,698) and negative binominal models for length-of-stay data (n=70,112). The number of DRGs differs widely across the 10 European countries (range: 2-14). Underlying this wide range is a different use of classification variables, especially secondary diagnoses and treatment options are considered to a different extent. In six countries, a standard set of patient characteristics and treatment variables explain the variation in costs or length of stay better than the DRG variables. This raises questions about the adequacy of the countries' DRG system or the lack of specific criteria, which could be used as classification variables. Copyright © 2012 John Wiley & Sons, Ltd.

Measuring wood specific gravity, correctly

Treesearch

G. Bruce Williamson; Michael C. Wiemann

2010-01-01

The specific gravity (SG) of wood is a measure of the amount of structural material a tree species allocates to support and strength. In recent years, wood specific gravity, traditionally a forester’s variable, has become the domain of ecologists exploring the universality of plant functional traits and conservationists estimating global carbon stocks. While these...

Forced Attention to Specific Applicant Qualifications: Impact on Physical Attractiveness and Sex of Applicant Biases.

ERIC Educational Resources Information Center

Cann, Arnie; And Others

1981-01-01

Undergraduates evaluated the qualifications of an attractive, average, or unattractive male or female applicant. Ratings of specific qualifications preceded or followed an overall and hiring decision rating. The order variable influenced ratings of specific qualifications but not the overall or hiring decision. Male and attractive applicants were…

The Specificity of Empathic Responses in Young Children.

ERIC Educational Resources Information Center

Marcus, Robert F.; Roke, Edward J.

Empathy as a personality variable and as related to social behavior in young children has not been examined for its specificity with regard to various affect classes but has generally been treated as a global response to all affect classes. Three kinds of evidence relative to the specificity of empathic responses are analyzed: (1) correlations…

Algebraic Functions of H-Functions with Specific Dependency Structure.

DTIC Science & Technology

1984-05-01

a study of its characteristic function. Such analysis is reproduced in books by Springer (17), Anderson (23), Feller (34,35), Mood and Graybill (52...following linearity property for expectations of jointly distributed random variables is derived. r 1 Theorem 1.1: If X and Y are real random variables...appear in American Journal of Mathematical and Management Science. 13. Mathai, A.M., and R.K. Saxena, "On linear combinations of stochastic variables

Prejudices in Cultural Contexts: Shared Stereotypes (Gender, Age) Versus Variable Stereotypes (Race, Ethnicity, Religion).

PubMed

Fiske, Susan T

2017-09-01

Some prejudices share cross-cultural patterns, but others are more variable and culture specific. Those sharing cross-cultural patterns (sexism, ageism) each combine societal status differences and intimate interdependence. For example, in stereotypes of sex and age, lower status groups-women and elders-gain stereotypic warmth (from their cooperative interdependence) but lose stereotypic competence (from their lower status); men and middle-aged adults show the opposite trade-off, stereotypically more competent than warm. Meta-analyses support these widespread ambivalent (mixed) stereotypes for gender and age across cultures. Social class stereotypes often share some similarities (cold but competent rich vs. warm but incompetent poor). These compensatory warmth versus competence stereotypes may function to manage common human dilemmas of interacting across societal and personal positions. However, other stereotypes are more variable and culture specific (ethnicity, race, religion). Case studies of specific race/ethnicities and religions reveal much more cultural variation in their stereotype content, supporting their being responses to particular cultural contexts, apparent accidents of history. To change stereotypes requires understanding their commonalities and differences, their origins and patterns across cultures.

Palaeoclimate dynamics : a voyage through scales

NASA Astrophysics Data System (ADS)

Crucifix, Michel; Mitsui, Takahito

2015-04-01

Our knowledge of climate dynamics depends on indirect observations of past climate evolution, as well as on what can be inferred from theoretical arguments. At the scale of the Cenozoic, it is common to define a framework of nested time scales, the longest time scale of interest being related to the slow tectonic evolution, then variability associated with or controlled by the astronomical forcing, and finally the fastest dynamics associated with the natural modes of variability of the ocean and the atmosphere. For example, in a model, the astronomical modes of variability may be simulated with deterministic equations under fixed boundary conditions representing the tectonic state, and associated with stochastic parameterisations of the ocean-atmosphere (chaotic) modes of motion. Bifurcations or, more generally, qualitative changes in climate dynamics may be scanned by changing slowly the tectonic state, in order to provide explanations to observed changes in regimes such as the appearance of ice ages and their changes in length or amplitude. The above framework, largely theorized by B. Saltzman, may still be partly justified but is in need of a review. We address here specifically three questions: To what extent astronomical variability interacts with natural modes of ocean - atmosphere variability ? Specifically, how does millennial variability (e.g.: Dansgaard-Oeschger events) fit the Saltzman scheme ? The astronomical forcing is quasi-periodic, and we recently showed that it may produce somewhat counter-intuitive dynamics associated with the emergence of strange non-chaotic attractors. What are the consequences on the spectrum of climate variability ? What are the effects of centennial climate variability on the slow variability of climate ? These three questions are addressed by reference to recently published material, with the objective of emphasising research questions to be explored in the near future.

Country-Specific Effects of Climate Variability on Human Migration

PubMed Central

Gray, Clark; Wise, Erika

2016-01-01

Involuntary human migration is among the social outcomes of greatest concern in the current era of global climate change. Responding to this concern, a growing number of studies have investigated the consequences of short to medium-term climate variability for human migration using demographic and econometric approaches. These studies have provided important insights, but at the same time have been significantly limited by lack of expertise in the use of climate data, access to cross-national data on migration, and attention to model specification. To address these limitations, we link data on internal and international migration over a 6-year period from 9,812 origin households in Kenya, Uganda, Nigeria, Burkina Faso and Senegal to high-resolution gridded climate data from both station and satellite sources. Analyses of these data using several plausible specifications reveal that climate variability has country-specific effects on migration: Migration tends to increase with temperature anomalies in Uganda, tends to decrease with temperature anomalies in Kenya and Burkina Faso, and shows no consistent relationship with temperature in Nigeria and Senegal. Consistent with previous studies, precipitation shows weak and inconsistent relationships with migration across countries. These results challenge generalizing narratives that foresee a consistent migratory response to climate change across the globe. PMID:27092012

Accounting for stimulus-specific variation in precision reveals a discrete capacity limit in visual working memory

PubMed Central

Pratte, Michael S.; Park, Young Eun; Rademaker, Rosanne L.; Tong, Frank

2016-01-01

If we view a visual scene that contains many objects, then momentarily close our eyes, some details persist while others seem to fade. Discrete models of visual working memory (VWM) assume that only a few items can be actively maintained in memory, beyond which pure guessing will emerge. Alternatively, continuous resource models assume that all items in a visual scene can be stored with some precision. Distinguishing between these competing models is challenging, however, as resource models that allow for stochastically variable precision (across items and trials) can produce error distributions that resemble random guessing behavior. Here, we evaluated the hypothesis that a major source of variability in VWM performance arises from systematic variation in precision across the stimuli themselves; such stimulus-specific variability can be incorporated into both discrete-capacity and variable-precision resource models. Participants viewed multiple oriented gratings, and then reported the orientation of a cued grating from memory. When modeling the overall distribution of VWM errors, we found that the variable-precision resource model outperformed the discrete model. However, VWM errors revealed a pronounced “oblique effect”, with larger errors for oblique than cardinal orientations. After this source of variability was incorporated into both models, we found that the discrete model provided a better account of VWM errors. Our results demonstrate that variable precision across the stimulus space can lead to an unwarranted advantage for resource models that assume stochastically variable precision. When these deterministic sources are adequately modeled, human working memory performance reveals evidence of a discrete capacity limit. PMID:28004957

Accounting for stimulus-specific variation in precision reveals a discrete capacity limit in visual working memory.

PubMed

Pratte, Michael S; Park, Young Eun; Rademaker, Rosanne L; Tong, Frank

2017-01-01

If we view a visual scene that contains many objects, then momentarily close our eyes, some details persist while others seem to fade. Discrete models of visual working memory (VWM) assume that only a few items can be actively maintained in memory, beyond which pure guessing will emerge. Alternatively, continuous resource models assume that all items in a visual scene can be stored with some precision. Distinguishing between these competing models is challenging, however, as resource models that allow for stochastically variable precision (across items and trials) can produce error distributions that resemble random guessing behavior. Here, we evaluated the hypothesis that a major source of variability in VWM performance arises from systematic variation in precision across the stimuli themselves; such stimulus-specific variability can be incorporated into both discrete-capacity and variable-precision resource models. Participants viewed multiple oriented gratings, and then reported the orientation of a cued grating from memory. When modeling the overall distribution of VWM errors, we found that the variable-precision resource model outperformed the discrete model. However, VWM errors revealed a pronounced "oblique effect," with larger errors for oblique than cardinal orientations. After this source of variability was incorporated into both models, we found that the discrete model provided a better account of VWM errors. Our results demonstrate that variable precision across the stimulus space can lead to an unwarranted advantage for resource models that assume stochastically variable precision. When these deterministic sources are adequately modeled, human working memory performance reveals evidence of a discrete capacity limit. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Life history theory predicts fish assemblage response to hydrologic regimes.

PubMed

Mims, Meryl C; Olden, Julian D

2012-01-01

The hydrologic regime is regarded as the primary driver of freshwater ecosystems, structuring the physical habitat template, providing connectivity, framing biotic interactions, and ultimately selecting for specific life histories of aquatic organisms. In the present study, we tested ecological theory predicting directional relationships between major dimensions of the flow regime and life history composition of fish assemblages in perennial free-flowing rivers throughout the continental United States. Using long-term discharge records and fish trait and survey data for 109 stream locations, we found that 11 out of 18 relationships (61%) tested between the three life history strategies (opportunistic, periodic, and equilibrium) and six hydrologic metrics (two each describing flow variability, predictability, and seasonality) were statistically significant (P < or = 0.05) according to quantile regression. Our results largely support a priori hypotheses of relationships between specific flow indices and relative prevalence of fish life history strategies, with 82% of all significant relationships observed supporting predictions from life history theory. Specifically, we found that (1) opportunistic strategists were positively related to measures of flow variability and negatively related to predictability and seasonality, (2) periodic strategists were positively related to high flow seasonality and negatively related to variability, and (3) the equilibrium strategists were negatively related to flow variability and positively related to predictability. Our study provides important empirical evidence illustrating the value of using life history theory to understand both the patterns and processes by which fish assemblage structure is shaped by adaptation to natural regimes of variability, predictability, and seasonality of critical flow events over broad biogeographic scales.

Fluxes all of the time? A primer on the temporal representativeness of FLUXNET

NASA Astrophysics Data System (ADS)

Chu, Housen; Baldocchi, Dennis D.; John, Ranjeet; Wolf, Sebastian; Reichstein, Markus

2017-02-01

FLUXNET, the global network of eddy covariance flux towers, provides the largest synthesized data set of CO2, H2O, and energy fluxes. To achieve the ultimate goal of providing flux information "everywhere and all of the time," studies have attempted to address the representativeness issue, i.e., whether measurements taken in a set of given locations and measurement periods can be extrapolated to a space- and time-explicit extent (e.g., terrestrial globe, 1982-2013 climatological baseline). This study focuses on the temporal representativeness of FLUXNET and tests whether site-specific measurement periods are sufficient to capture the natural variability of climatological and biological conditions. FLUXNET is unevenly representative across sites in terms of the measurement lengths and potentials of extrapolation in time. Similarity of driver conditions among years generally enables the extrapolation of flux information beyond measurement periods. Yet such extrapolation potentials are further constrained by site-specific variability of driver conditions. Several driver variables such as air temperature, diurnal temperature range, potential evapotranspiration, and normalized difference vegetation index had detectable trends and/or breakpoints within the baseline period, and flux measurements generally covered similar and biased conditions in those drivers. About 38% and 60% of FLUXNET sites adequately sampled the mean conditions and interannual variability of all driver conditions, respectively. For long-record sites (≥15 years) the percentages increased to 59% and 69%, respectively. However, the justification of temporal representativeness should not rely solely on the lengths of measurements. Whenever possible, site-specific consideration (e.g., trend, breakpoint, and interannual variability in drivers) should be taken into account.

Quantifying Intrinsic and Extrinsic Variability in Stochastic Gene Expression Models

PubMed Central

Singh, Abhyudai; Soltani, Mohammad

2013-01-01

Genetically identical cell populations exhibit considerable intercellular variation in the level of a given protein or mRNA. Both intrinsic and extrinsic sources of noise drive this variability in gene expression. More specifically, extrinsic noise is the expression variability that arises from cell-to-cell differences in cell-specific factors such as enzyme levels, cell size and cell cycle stage. In contrast, intrinsic noise is the expression variability that is not accounted for by extrinsic noise, and typically arises from the inherent stochastic nature of biochemical processes. Two-color reporter experiments are employed to decompose expression variability into its intrinsic and extrinsic noise components. Analytical formulas for intrinsic and extrinsic noise are derived for a class of stochastic gene expression models, where variations in cell-specific factors cause fluctuations in model parameters, in particular, transcription and/or translation rate fluctuations. Assuming mRNA production occurs in random bursts, transcription rate is represented by either the burst frequency (how often the bursts occur) or the burst size (number of mRNAs produced in each burst). Our analysis shows that fluctuations in the transcription burst frequency enhance extrinsic noise but do not affect the intrinsic noise. On the contrary, fluctuations in the transcription burst size or mRNA translation rate dramatically increase both intrinsic and extrinsic noise components. Interestingly, simultaneous fluctuations in transcription and translation rates arising from randomness in ATP abundance can decrease intrinsic noise measured in a two-color reporter assay. Finally, we discuss how these formulas can be combined with single-cell gene expression data from two-color reporter experiments for estimating model parameters. PMID:24391934

Quantifying intrinsic and extrinsic variability in stochastic gene expression models.

PubMed

Singh, Abhyudai; Soltani, Mohammad

2013-01-01

Genetically identical cell populations exhibit considerable intercellular variation in the level of a given protein or mRNA. Both intrinsic and extrinsic sources of noise drive this variability in gene expression. More specifically, extrinsic noise is the expression variability that arises from cell-to-cell differences in cell-specific factors such as enzyme levels, cell size and cell cycle stage. In contrast, intrinsic noise is the expression variability that is not accounted for by extrinsic noise, and typically arises from the inherent stochastic nature of biochemical processes. Two-color reporter experiments are employed to decompose expression variability into its intrinsic and extrinsic noise components. Analytical formulas for intrinsic and extrinsic noise are derived for a class of stochastic gene expression models, where variations in cell-specific factors cause fluctuations in model parameters, in particular, transcription and/or translation rate fluctuations. Assuming mRNA production occurs in random bursts, transcription rate is represented by either the burst frequency (how often the bursts occur) or the burst size (number of mRNAs produced in each burst). Our analysis shows that fluctuations in the transcription burst frequency enhance extrinsic noise but do not affect the intrinsic noise. On the contrary, fluctuations in the transcription burst size or mRNA translation rate dramatically increase both intrinsic and extrinsic noise components. Interestingly, simultaneous fluctuations in transcription and translation rates arising from randomness in ATP abundance can decrease intrinsic noise measured in a two-color reporter assay. Finally, we discuss how these formulas can be combined with single-cell gene expression data from two-color reporter experiments for estimating model parameters.

Age-dependent radial increases in wood specific gravity of tropical pioneers in Costa Rica

Treesearch

Bruce G. Williamson; Michael C. Wiemann

2010-01-01

Wood specific gravity is the single best descriptor of wood functional properties and tree life-history traits, and it is the most important variable in estimating carbon stocks in forests. Tropical pioneer trees produce wood of increasing specific gravity across the trunk radius as they grow in stature. Here, we tested whether radial increases in wood specific gravity...

Assessing Weather-Yield Relationships in Rice at Local Scale Using Data Mining Approaches

PubMed Central

Delerce, Sylvain; Dorado, Hugo; Grillon, Alexandre; Rebolledo, Maria Camila; Prager, Steven D.; Patiño, Victor Hugo; Garcés Varón, Gabriel; Jiménez, Daniel

2016-01-01

Seasonal and inter-annual climate variability have become important issues for farmers, and climate change has been shown to increase them. Simultaneously farmers and agricultural organizations are increasingly collecting observational data about in situ crop performance. Agriculture thus needs new tools to cope with changing environmental conditions and to take advantage of these data. Data mining techniques make it possible to extract embedded knowledge associated with farmer experiences from these large observational datasets in order to identify best practices for adapting to climate variability. We introduce new approaches through a case study on irrigated and rainfed rice in Colombia. Preexisting observational datasets of commercial harvest records were combined with in situ daily weather series. Using Conditional Inference Forest and clustering techniques, we assessed the relationships between climatic factors and crop yield variability at the local scale for specific cultivars and growth stages. The analysis showed clear relationships in the various location-cultivar combinations, with climatic factors explaining 6 to 46% of spatiotemporal variability in yield, and with crop responses to weather being non-linear and cultivar-specific. Climatic factors affected cultivars differently during each stage of development. For instance, one cultivar was affected by high nighttime temperatures in the reproductive stage but responded positively to accumulated solar radiation during the ripening stage. Another was affected by high nighttime temperatures during both the vegetative and reproductive stages. Clustering of the weather patterns corresponding to individual cropping events revealed different groups of weather patterns for irrigated and rainfed systems with contrasting yield levels. Best-suited cultivars were identified for some weather patterns, making weather-site-specific recommendations possible. This study illustrates the potential of data mining for adding value to existing observational data in agriculture by allowing embedded knowledge to be quickly leveraged. It generates site-specific information on cultivar response to climatic factors and supports on-farm management decisions for adaptation to climate variability. PMID:27560980

Assessing Weather-Yield Relationships in Rice at Local Scale Using Data Mining Approaches.

PubMed

Delerce, Sylvain; Dorado, Hugo; Grillon, Alexandre; Rebolledo, Maria Camila; Prager, Steven D; Patiño, Victor Hugo; Garcés Varón, Gabriel; Jiménez, Daniel

2016-01-01

Seasonal and inter-annual climate variability have become important issues for farmers, and climate change has been shown to increase them. Simultaneously farmers and agricultural organizations are increasingly collecting observational data about in situ crop performance. Agriculture thus needs new tools to cope with changing environmental conditions and to take advantage of these data. Data mining techniques make it possible to extract embedded knowledge associated with farmer experiences from these large observational datasets in order to identify best practices for adapting to climate variability. We introduce new approaches through a case study on irrigated and rainfed rice in Colombia. Preexisting observational datasets of commercial harvest records were combined with in situ daily weather series. Using Conditional Inference Forest and clustering techniques, we assessed the relationships between climatic factors and crop yield variability at the local scale for specific cultivars and growth stages. The analysis showed clear relationships in the various location-cultivar combinations, with climatic factors explaining 6 to 46% of spatiotemporal variability in yield, and with crop responses to weather being non-linear and cultivar-specific. Climatic factors affected cultivars differently during each stage of development. For instance, one cultivar was affected by high nighttime temperatures in the reproductive stage but responded positively to accumulated solar radiation during the ripening stage. Another was affected by high nighttime temperatures during both the vegetative and reproductive stages. Clustering of the weather patterns corresponding to individual cropping events revealed different groups of weather patterns for irrigated and rainfed systems with contrasting yield levels. Best-suited cultivars were identified for some weather patterns, making weather-site-specific recommendations possible. This study illustrates the potential of data mining for adding value to existing observational data in agriculture by allowing embedded knowledge to be quickly leveraged. It generates site-specific information on cultivar response to climatic factors and supports on-farm management decisions for adaptation to climate variability.

Performance evaluation of a center pivot variable rate irrigation system

USDA-ARS?s Scientific Manuscript database

Variable Rate Irrigation (VRI) for center pivots offers potential to match specific application rates to non-uniform soil conditions along the length of the lateral. The benefit of such systems is influenced by the areal extent of these variations and the smallest scale to which the irrigation syste...

Complex Variables throughout the Curriculum

ERIC Educational Resources Information Center

D'Angelo, John P.

2017-01-01

We offer many specific detailed examples, several of which are new, that instructors can use (in lecture or as student projects) to revitalize the role of complex variables throughout the curriculum. We conclude with three primary recommendations: revise the syllabus of Calculus II to allow early introductions of complex numbers and linear…

Variable thickness transient ground-water flow model. Volume 1. Formulation

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

Reisenauer, A.E.

1979-12-01

Mathematical formulation for the variable thickness transient (VTT) model of an aquifer system is presented. The basic assumptions are described. Specific data requirements for the physical parameters are discussed. The boundary definitions and solution techniques of the numerical formulation of the system of equations are presented.

Further Evidence on Field Differences in Consensus from the NSF Peer Review Studies.

ERIC Educational Resources Information Center

Hargens, Lowell L.

1988-01-01

Cole, Simon, and Cole identify the following variables that may affect scholarly journal rejection rates: (1) field-specific publication norms; (2) diffuseness of journal structures; and (3) differences in training practices. However, they do not explain why the variables they identify covary across disciplines. (BJV)

Generalized Structured Component Analysis with Latent Interactions

ERIC Educational Resources Information Center

Hwang, Heungsun; Ho, Moon-Ho Ringo; Lee, Jonathan

2010-01-01

Generalized structured component analysis (GSCA) is a component-based approach to structural equation modeling. In practice, researchers may often be interested in examining the interaction effects of latent variables. However, GSCA has been geared only for the specification and testing of the main effects of variables. Thus, an extension of GSCA…

Variable rate application of nematicides on cotton fields: A promising site-specific management strategy.

USDA-ARS?s Scientific Manuscript database

Field tests were conducted to determine if differences in response to nematicide application (i.e., root-knot nematode (RKN) population levels, cotton yield, and profitability) occurred among RKN management zones (MZ). The MZ were delineated using variables related to soil texture, including appare...

Dynamic prescription maps for site-specific variable rate irrigation of cotton

USDA-ARS?s Scientific Manuscript database

A prescription map is a set of instructions that controls a variable rate irrigation (VRI) system. These maps, which may be based on prior yield, soil texture, topography, or soil electrical conductivity data, are often manually applied at the beginning of an irrigation season and remain static. The...

Variable Rate Application of Nematicides on Cotton Fields: A Promising Site-Specific Management Strategy

USDA-ARS?s Scientific Manuscript database

Cotton (Gossypium hirsutum L.) lint yield losses associated with southern root-knot nematode [Meloidogyne incognita] (RKN) parasitism have increased during the last 20 years. The hypothesis that variable rate application of nematicides can reduce yield losses and reduce the risk for under- and over-...

Sex-Role Ideology and the Aspirations of High School Girls

ERIC Educational Resources Information Center

Gaskell, Jane

1977-01-01

Variables specifically related to sex-role definitions in our society must be considered in accounting for the generally lower aspirations of women since after controlling the variables of social class and academic achievement, sex continues to make a difference in the aspiration levels of high school girls. (MJB)

Climate variability and plant response at the Santa Rita Experimental Range, Arizona

Treesearch

Michael A. Crimmins; Theresa M. Mau-Crimmins

2003-01-01

Climatic variability is reflected in differential establishment, persistence, and spread of plant species. Although studies have investigated these relationships for some species and functional groups, few have attempted to characterize the specific sequences of climatic conditions at various temporal scales (subseasonal, seasonal, and interannual) associated with...

Environmental Concern and Sociodemographic Variables: A Study of Statistical Models

ERIC Educational Resources Information Center

Xiao, Chenyang; McCright, Aaron M.

2007-01-01

Studies of the social bases of environmental concern over the past 30 years have produced somewhat inconsistent results regarding the effects of sociodemographic variables, such as gender, income, and place of residence. The authors argue that model specification errors resulting from violation of two statistical assumptions (interval-level…

EFFECTS OF APPLIANCE TYPE AND OPERATING VARIABLES ON WOODSTOVE EMISSIONS: VOLUME II. APPENDICIES D-F.

EPA Science Inventory

The report gives results of a project, in support of the intergared Air Cancer Project (IACP), to provide data on the specific effects of appliance type and operating variables on woodstove emissions. samples of particulate material and volatile organic compounds (VOCs) were coll...

Site-specific cotton management: Soil measurements

USDA-ARS?s Scientific Manuscript database

oil variability within fields has a large effect on crop growth and yield, often due to variations in soil texture and water holding capacity. This is particularly true in the alluvial soils of the Mississippi Delta, where profile sand contents can range from 20% to 90% within a field. Variable-rate...

The Effects of Family Size, Birth Order, Sibling Separation and Crowding on the Academic Achievement of Boys and Girls

ERIC Educational Resources Information Center

Nuttall, Ena Vazquez; And Others

1976-01-01

Family constellation variables such as family size, birth order, spacing of children, and crowding were significantly associated with academic achievement when IQ was controlled. The effects of family constellation variables were found to be sex specific. (RC)

Effect of Response Practice Variables on Learning Spelling and Sight Vocabulary.

ERIC Educational Resources Information Center

Cuvo, Anthony J.; And Others

1995-01-01

Response practice variables for learning spelling and sight vocabulary were studied in 4 experiments involving a total of 18 rehabilitation clients and adolescents with developmental disabilities or behavior disorders. The experiments specifically examined the "cover write" method, written versus oral practice, less versus more response practice,…

Developing a Predictive Metric to Assess School Viability

ERIC Educational Resources Information Center

James, John T.; Tichy, Karen L.; Collins, Alan; Schwob, John

2008-01-01

This article examines a wide range of parish school indicators that can be used to predict long-term viability. The study reported in this article explored the relationship between demographic variables, financial variables, and parish grade school closures in the Archdiocese of Saint Louis. Specifically, this study investigated whether…

Selection Practices of Group Leaders: A National Survey.

ERIC Educational Resources Information Center

Riva, Maria T.; Lippert, Laurel; Tackett, M. Jan

2000-01-01

Study surveys the selection practices of group leaders. Explores methods of selection, variables used to make selection decisions, and the types of selection errors that leaders have experienced. Results suggest that group leaders use clinical judgment to make selection decisions and endorse using some specific variables in selection. (Contains 22…

Frequency-Specific Fractal Analysis of Postural Control Accounts for Control Strategies

PubMed Central

Gilfriche, Pierre; Deschodt-Arsac, Véronique; Blons, Estelle; Arsac, Laurent M.

2018-01-01

Diverse indicators of postural control in Humans have been explored for decades, mostly based on the trajectory of the center-of-pressure. Classical approaches focus on variability, based on the notion that if a posture is too variable, the subject is not stable. Going deeper, an improved understanding of underlying physiology has been gained from studying variability in different frequency ranges, pointing to specific short-loops (proprioception), and long-loops (visuo-vestibular) in neural control. More recently, fractal analyses have proliferated and become useful additional metrics of postural control. They allowed identifying two scaling phenomena, respectively in short and long timescales. Here, we show that one of the most widely used methods for fractal analysis, Detrended Fluctuation Analysis, could be enhanced to account for scalings on specific frequency ranges. By computing and filtering a bank of synthetic fractal signals, we established how scaling analysis can be focused on specific frequency components. We called the obtained method Frequency-specific Fractal Analysis (FsFA) and used it to associate the two scaling phenomena of postural control to proprioceptive-based control loop and visuo-vestibular based control loop. After that, convincing arguments of method validity came from an application on the study of unaltered vs. altered postural control in athletes. Overall, the analysis suggests that at least two timescales contribute to postural control: a velocity-based control in short timescales relying on proprioceptive sensors, and a position-based control in longer timescales with visuo-vestibular sensors, which is a brand-new vision of postural control. Frequency-specific scaling exponents are promising markers of control strategies in Humans. PMID:29643816

Retrospective Analysis of Inflight Exercise Loading and Physiological Outcomes

NASA Technical Reports Server (NTRS)

Ploutz-Snyder, L. L.; Buxton, R. E.; De Witt, J. K.; Guilliams, M. E.; Hanson, A. M.; Peters, B. T.; Pandorf, M. M. Scott; Sibonga, J. D.

2014-01-01

Astronauts perform exercise throughout their missions to counter the health declines that occur as a result of long-term exposure to weightlessness. Although all astronauts perform exercise during their missions, the specific prescriptions, and thus the mechanical loading, differs among individuals. For example, inflight ground reaction force data indicate that subject-specific differences exist in foot forces created when exercising on the second-generation treadmill (T2) [1]. The current exercise devices allow astronauts to complete prescriptions at higher intensities, resulting in greater benefits with increased efficiency. Although physiological outcomes have improved, the specific factors related to the increased benefits are unknown. In-flight exercise hardware collect data that allows for exploratory analyses to determine if specific performance factors relate to physiological outcomes. These analyses are vital for understanding which components of exercise are most critical for optimal human health and performance. The relationship between exercise performance variables and physiological changes during flight has yet to be fully investigated. Identifying the critical performance variables that relate to improved physiological outcomes is vital for creating current and future exercise prescriptions to optimize astronaut health. The specific aims of this project are: 1) To quantify the exercise-related mechanical loading experienced by crewmembers on T2 and ARED during their mission on ISS; 2) To explore relationships between exercise loading variables, bone, and muscle health changes during the mission; 3) To determine if specific mechanical loading variables are more critical than others in protecting physiology; 4) To develop methodology for operational use in monitoring accumulated training loads during crew exercise programs. This retrospective analysis, which is currently in progress, is being conducted using data from astronauts that have flown long-duration missions onboard the ISS and have had access to exercise on the T2 and the Advanced Resistive Exercise Device (ARED). The specific exercise prescriptions vary for each astronaut. General exercise summary metrics will be developed to quantify exercise intensities, volumes, and durations for each subject. Where available, ground reaction force data will be used to quantify mechanical loading experienced by each astronaut. These inflight exercise metrics will be investigated relative to changes in pre- to post-flight bone and muscle health to identify which specific variables are related with improved or degraded physiological outcomes. The information generated from this analysis will fill gaps related to typical bone loading characterization, exercise performance capability, exercise volume and efficiency, and importance of exercise hardware. In addition, methods for quantification of exercise loading for use in monitoring the exercise programs during future space missions will be explored with the intent to inform exercise scientists and trainers as to the critical aspects of inflight exercise prescriptions.

So Many Brands and Varieties to Choose from: Does This Compromise the Control of Food Intake in Humans?

PubMed

Hardman, Charlotte A; Ferriday, Danielle; Kyle, Lesley; Rogers, Peter J; Brunstrom, Jeffrey M

2015-01-01

The recent rise in obesity is widely attributed to changes in the dietary environment (e.g., increased availability of energy-dense foods and larger portion sizes). However, a critical feature of our "obesogenic environment" may have been overlooked - the dramatic increase in "dietary variability" (the tendency for specific mass-produced foods to be available in numerous varieties that differ in energy content). In this study we tested the hypothesis that dietary variability compromises the control of food intake in humans. Specifically, we examined the effects of dietary variability in pepperoni pizza on two key outcome variables; i) compensation for calories in pepperoni pizza and ii) expectations about the satiating properties of pepperoni pizza (expected satiation). We reasoned that dietary variability might generate uncertainty about the postingestive effects of a food. An internet-based questionnaire was completed by 199 adults. This revealed substantial variation in exposure to different varieties of pepperoni pizza. In a follow-up study (n= 66; 65% female), high pizza variability was associated with i) poorer compensation for calories in pepperoni pizza and ii) lower expected satiation for pepperoni pizza. Furthermore, the effect of uncertainty on caloric compensation was moderated by individual differences in decision making (loss aversion). For the first time, these findings highlight a process by which dietary variability may compromise food-intake control in humans. This is important because it exposes a new feature of Western diets (processed foods in particular) that might contribute to overeating and obesity.

Pharmacogenomics in pediatric rheumatology.

PubMed

Becker, Mara L

2012-09-01

Despite major advancements in therapeutics, variability in drug response remains a challenge in both adults and children diagnosed with rheumatic disease. The genetic contribution to interindividual variability has emerged as a promising avenue of exploration; however, challenges remain in making this knowledge relevant in the clinical realm. New genetic associations in patients with rheumatic disease have been reported for disease modifying antirheumatic drugs, antimetabolites and biologic drugs. However, many of these findings are in need of replication, and few have taken into account the concept of ontogeny, specific to pediatrics. In the current era in which we practice, genetic variation will undoubtedly contribute to variability in therapeutic response and may be a factor that will ultimately impact individualized care. However, preliminary studies have shown that there are many hurdles that need to be overcome as we explore pharmacogenomic associations specifically in the field of pediatric rheumatology.

Symbolic dynamics marker of heart rate variability combined with clinical variables enhance obstructive sleep apnea screening

NASA Astrophysics Data System (ADS)

Ravelo-García, A. G.; Saavedra-Santana, P.; Juliá-Serdá, G.; Navarro-Mesa, J. L.; Navarro-Esteva, J.; Álvarez-López, X.; Gapelyuk, A.; Penzel, T.; Wessel, N.

2014-06-01

Many sleep centres try to perform a reduced portable test in order to decrease the number of overnight polysomnographies that are expensive, time-consuming, and disturbing. With some limitations, heart rate variability (HRV) has been useful in this task. The aim of this investigation was to evaluate if inclusion of symbolic dynamics variables to a logistic regression model integrating clinical and physical variables, can improve the detection of subjects for further polysomnographies. To our knowledge, this is the first contribution that innovates in that strategy. A group of 133 patients has been referred to the sleep center for suspected sleep apnea. Clinical assessment of the patients consisted of a sleep related questionnaire and a physical examination. The clinical variables related to apnea and selected in the statistical model were age (p < 10-3), neck circumference (p < 10-3), score on a questionnaire scale intended to quantify daytime sleepiness (p < 10-3), and intensity of snoring (p < 10-3). The validation of this model demonstrated an increase in classification performance when a variable based on non-linear dynamics of HRV (p < 0.01) was used additionally to the other variables. For diagnostic rule based only on clinical and physical variables, the corresponding area under the receiver operating characteristic (ROC) curve was 0.907 (95% confidence interval (CI) = 0.848, 0.967), (sensitivity 87.10% and specificity 80%). For the model including the average of a symbolic dynamic variable, the area under the ROC curve was increased to 0.941 (95% = 0.897, 0.985), (sensitivity 88.71% and specificity 82.86%). In conclusion, symbolic dynamics, coupled with significant clinical and physical variables can help to prioritize polysomnographies in patients with a high probability of apnea. In addition, the processing of the HRV is a well established low cost and robust technique.

Design Specification Issues in Time-Series Intervention Models.

ERIC Educational Resources Information Center

Huitema, Bradley E.; McKean, Joseph W.

2000-01-01

Presents examples of egregious errors of interpretation in time-series intervention models and makes recommendations regarding the correct specification of the design matrix. Discusses the profound effects of variants of the slope change variable in the design matrix. (SLD)

Autosomal Dominant Cataract: Intrafamilial Phenotypic Variability, Interocular Asymmetry, and Variable Progression in Four Chilean Families

PubMed Central

Shafie, Suraiya M.; Barria von-Bischhoffshausen, Fernando R.; Bateman, J. Bronwyn

2006-01-01

PURPOSE To document intrafamilial and interocular phenotypic variability of autosomal dominant cataract (ADC). DESIGN Prospective observational case series. METHODS We performed ophthalmologic examination in four Chilean ADC families. RESULTS The families exhibited variability with respect to morphology, location with the lens, color and density of cataracts among affected members. We documented asymmetry between eyes in the morphology, location within the lens, color and density of cataracts, and a variable rate of progression. CONCLUSIONS The cataracts in these families exhibit wide intrafamilial and interocular phenotypic variability, supporting the premise that the mutated genes are expressed differentially in individuals and between eyes; other genes or environmental factors may be the bases for this variability. Marked progression among some family members underscores the variable clinical course of a common mutation within a family. Like retinitis pigmentosa, classification of ADC will be most useful if based on the gene and specific mutation. PMID:16564818

Output variability across animals and levels in a motor system

PubMed Central

Norris, Brian J; Günay, Cengiz; Kueh, Daniel

2018-01-01

Rhythmic behaviors vary across individuals. We investigated the sources of this output variability across a motor system, from the central pattern generator (CPG) to the motor plant. In the bilaterally symmetric leech heartbeat system, the CPG orchestrates two coordinations in the bilateral hearts with different intersegmental phase relations (Δϕ) and periodic side-to-side switches. Population variability is large. We show that the system is precise within a coordination, that differences in repetitions of a coordination contribute little to population output variability, but that differences between bilaterally homologous cells may contribute to some of this variability. Nevertheless, much output variability is likely associated with genetic and life history differences among individuals. Variability of Δϕ were coordination-specific: similar at all levels in one, but significantly lower for the motor pattern than the CPG pattern in the other. Mechanisms that transform CPG output to motor neurons may limit output variability in the motor pattern. PMID:29345614

A neural circuit mechanism for regulating vocal variability during song learning in zebra finches.

PubMed

Garst-Orozco, Jonathan; Babadi, Baktash; Ölveczky, Bence P

2014-12-15

Motor skill learning is characterized by improved performance and reduced motor variability. The neural mechanisms that couple skill level and variability, however, are not known. The zebra finch, a songbird, presents a unique opportunity to address this question because production of learned song and induction of vocal variability are instantiated in distinct circuits that converge on a motor cortex analogue controlling vocal output. To probe the interplay between learning and variability, we made intracellular recordings from neurons in this area, characterizing how their inputs from the functionally distinct pathways change throughout song development. We found that inputs that drive stereotyped song-patterns are strengthened and pruned, while inputs that induce variability remain unchanged. A simple network model showed that strengthening and pruning of action-specific connections reduces the sensitivity of motor control circuits to variable input and neural 'noise'. This identifies a simple and general mechanism for learning-related regulation of motor variability.

The GISS global climate-middle atmosphere model. II - Model variability due to interactions between planetary waves, the mean circulation and gravity wave drag

NASA Technical Reports Server (NTRS)

Rind, D.; Suozzo, R.; Balachandran, N. K.

1988-01-01

The variability which arises in the GISS Global Climate-Middle Atmosphere Model on two time scales is reviewed: interannual standard deviations, derived from the five-year control run, and intraseasonal variability as exemplified by statospheric warnings. The model's extratropical variability for both mean fields and eddy statistics appears reasonable when compared with observations, while the tropical wind variability near the stratopause may be excessive possibly, due to inertial oscillations. Both wave 1 and wave 2 warmings develop, with connections to tropospheric forcing. Variability on both time scales results from a complex set of interactions among planetary waves, the mean circulation, and gravity wave drag. Specific examples of these interactions are presented, which imply that variability in gravity wave forcing and drag may be an important component of the variability of the middle atmosphere.

Host specificity in biological control: insights from opportunistic pathogens

PubMed Central

Brodeur, Jacques

2012-01-01

Host/prey specificity is a significant concern in biological control. It influences the effectiveness of a natural enemy and the risks it might have on non-target organisms. Furthermore, narrow host specificity can be a limiting factor for the commercialization of natural enemies. Given the great diversity in taxonomy and mode of action of natural enemies, host specificity is a highly variable biological trait. This variability can be illustrated by opportunist fungi from the genus Lecanicillium, which have the capacity to exploit a wide range of hosts – from arthropod pests to fungi causing plant diseases – through different modes of action. Processes determining evolutionary trajectories in host specificity are closely linked to the modes of action of the natural enemy. This hypothesis is supported by advances in fungal genomics concerning the identity of genes and biological traits that are required for the evolution of life history strategies and host range. Despite the significance of specificity, we still need to develop a conceptual framework for better understanding of the relationship between specialization and successful biological control. The emergence of opportunistic pathogens and the development of ‘omic’ technologies offer new opportunities to investigate evolutionary principles and applications of the specificity of biocontrol agents. PMID:22949922

Specificity and detail in autobiographical memory: Same or different constructs?

PubMed

Kyung, Yoonhee; Yanes-Lukin, Paula; Roberts, John E

2016-01-01

Research on autobiographical memory has focused on whether memories are coded as specific (i.e., describe a single event that happened at a particular time and place). Although some theory and research suggests that the amount of detail in autobiographical memories reflects a similar underlying construct as memory specificity, past research has not investigated whether these variables converge. Therefore, the present study compared the proportion of specific memories and the amount of detail embedded in memory responses to cue words. Results demonstrated that memory detail and proportion of specific memories were not correlated with each other and showed different patterns of association with other conceptually relevant variables. When responses to neutral cue words were examined in multiple linear and logistic regression analyses, the proportion of specific memories uniquely predicted less depressive symptoms, low emotional avoidance, lower emotion reactivity, better executive control and lower rumination, whereas the amount of memory detail uniquely predicted the presence of depression diagnosis, as well as greater depressive symptoms, subjective stress, emotion reactivity and rumination. Findings suggest that the ability to retrieve specific memories and the tendency to retrieve detailed personal memories reflect different constructs that have different implications in the development of emotional distress.

Bias, Confounding, and Interaction: Lions and Tigers, and Bears, Oh My!

PubMed

Vetter, Thomas R; Mascha, Edward J

2017-09-01

Epidemiologists seek to make a valid inference about the causal effect between an exposure and a disease in a specific population, using representative sample data from a specific population. Clinical researchers likewise seek to make a valid inference about the association between an intervention and outcome(s) in a specific population, based upon their randomly collected, representative sample data. Both do so by using the available data about the sample variable to make a valid estimate about its corresponding or underlying, but unknown population parameter. Random error in an experiment can be due to the natural, periodic fluctuation or variation in the accuracy or precision of virtually any data sampling technique or health measurement tool or scale. In a clinical research study, random error can be due to not only innate human variability but also purely chance. Systematic error in an experiment arises from an innate flaw in the data sampling technique or measurement instrument. In the clinical research setting, systematic error is more commonly referred to as systematic bias. The most commonly encountered types of bias in anesthesia, perioperative, critical care, and pain medicine research include recall bias, observational bias (Hawthorne effect), attrition bias, misclassification or informational bias, and selection bias. A confounding variable is a factor associated with both the exposure of interest and the outcome of interest. A confounding variable (confounding factor or confounder) is a variable that correlates (positively or negatively) with both the exposure and outcome. Confounding is typically not an issue in a randomized trial because the randomized groups are sufficiently balanced on all potential confounding variables, both observed and nonobserved. However, confounding can be a major problem with any observational (nonrandomized) study. Ignoring confounding in an observational study will often result in a "distorted" or incorrect estimate of the association or treatment effect. Interaction among variables, also known as effect modification, exists when the effect of 1 explanatory variable on the outcome depends on the particular level or value of another explanatory variable. Bias and confounding are common potential explanations for statistically significant associations between exposure and outcome when the true relationship is noncausal. Understanding interactions is vital to proper interpretation of treatment effects. These complex concepts should be consistently and appropriately considered whenever one is not only designing but also analyzing and interpreting data from a randomized trial or observational study.

Altitude Performance Characteristics of Tail-pipe Burner with Variable-area Exhaust Nozzle

NASA Technical Reports Server (NTRS)

Jansen, Emmert T; Thorman, H Carl

1950-01-01

An investigation was conducted in the NACA Lewis altitude wind tunnel to determine effect of altitude and flight Mach number on performance of tail-pipe burner equipped with variable-area exhaust nozzle and installed on full-scale turbojet engine. At a given flight Mach number, with constant exhaust-gas and turbine-outlet temperatures, increasing altitude lowered the tail-pipe combustion efficiency and raised the specific fuel consumption while the augmented thrust ratio remained approximately constant. At a given altitude, increasing flight Mach number raised the combustion efficiency and augmented thrust ratio and lowered the specific fuel consumption.

Spectrum sensitivity, energy yield, and revenue prediction of PV and CPV modules

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

Kinsey, Geoffrey S., E-mail: Geoffrey.kinsey@ee.doe.gov

2015-09-28

Impact on module performance of spectral irradiance variation has been determined for III-V multijunctions compared against the four most common flat-plate module types (cadmium telluride, multicrystalline silicon, copper indium gallium selenide, and monocrystalline silicon. Hour-by-hour representative spectra were generated using atmospheric variables for Albuquerque, New Mexico, USA. Convolution with published values for external quantum efficiency gave the predicted current output. When combined with specifications of commercial PV modules, energy yield and revenue were predicted. This approach provides a means for optimizing PV module design based on various site-specific temporal variables.

Spectrum sensitivity, energy yield, and revenue prediction of PV and CPV modules

NASA Astrophysics Data System (ADS)

Kinsey, Geoffrey S.

2015-09-01

Impact on module performance of spectral irradiance variation has been determined for III-V multijunctions compared against the four most common flat-plate module types (cadmium telluride, multicrystalline silicon, copper indium gallium selenide, and monocrystalline silicon. Hour-by-hour representative spectra were generated using atmospheric variables for Albuquerque, New Mexico, USA. Convolution with published values for external quantum efficiency gave the predicted current output. When combined with specifications of commercial PV modules, energy yield and revenue were predicted. This approach provides a means for optimizing PV module design based on various site-specific temporal variables.

A Novel Information-Theoretic Approach for Variable Clustering and Predictive Modeling Using Dirichlet Process Mixtures

PubMed Central

Chen, Yun; Yang, Hui

2016-01-01

In the era of big data, there are increasing interests on clustering variables for the minimization of data redundancy and the maximization of variable relevancy. Existing clustering methods, however, depend on nontrivial assumptions about the data structure. Note that nonlinear interdependence among variables poses significant challenges on the traditional framework of predictive modeling. In the present work, we reformulate the problem of variable clustering from an information theoretic perspective that does not require the assumption of data structure for the identification of nonlinear interdependence among variables. Specifically, we propose the use of mutual information to characterize and measure nonlinear correlation structures among variables. Further, we develop Dirichlet process (DP) models to cluster variables based on the mutual-information measures among variables. Finally, orthonormalized variables in each cluster are integrated with group elastic-net model to improve the performance of predictive modeling. Both simulation and real-world case studies showed that the proposed methodology not only effectively reveals the nonlinear interdependence structures among variables but also outperforms traditional variable clustering algorithms such as hierarchical clustering. PMID:27966581

A Novel Information-Theoretic Approach for Variable Clustering and Predictive Modeling Using Dirichlet Process Mixtures.

PubMed

Chen, Yun; Yang, Hui

2016-12-14

In the era of big data, there are increasing interests on clustering variables for the minimization of data redundancy and the maximization of variable relevancy. Existing clustering methods, however, depend on nontrivial assumptions about the data structure. Note that nonlinear interdependence among variables poses significant challenges on the traditional framework of predictive modeling. In the present work, we reformulate the problem of variable clustering from an information theoretic perspective that does not require the assumption of data structure for the identification of nonlinear interdependence among variables. Specifically, we propose the use of mutual information to characterize and measure nonlinear correlation structures among variables. Further, we develop Dirichlet process (DP) models to cluster variables based on the mutual-information measures among variables. Finally, orthonormalized variables in each cluster are integrated with group elastic-net model to improve the performance of predictive modeling. Both simulation and real-world case studies showed that the proposed methodology not only effectively reveals the nonlinear interdependence structures among variables but also outperforms traditional variable clustering algorithms such as hierarchical clustering.

Multi-level multi-task learning for modeling cross-scale interactions in nested geospatial data

USGS Publications Warehouse

Yuan, Shuai; Zhou, Jiayu; Tan, Pang-Ning; Fergus, Emi; Wagner, Tyler; Sorrano, Patricia

2017-01-01

Predictive modeling of nested geospatial data is a challenging problem as the models must take into account potential interactions among variables defined at different spatial scales. These cross-scale interactions, as they are commonly known, are particularly important to understand relationships among ecological properties at macroscales. In this paper, we present a novel, multi-level multi-task learning framework for modeling nested geospatial data in the lake ecology domain. Specifically, we consider region-specific models to predict lake water quality from multi-scaled factors. Our framework enables distinct models to be developed for each region using both its local and regional information. The framework also allows information to be shared among the region-specific models through their common set of latent factors. Such information sharing helps to create more robust models especially for regions with limited or no training data. In addition, the framework can automatically determine cross-scale interactions between the regional variables and the local variables that are nested within them. Our experimental results show that the proposed framework outperforms all the baseline methods in at least 64% of the regions for 3 out of 4 lake water quality datasets evaluated in this study. Furthermore, the latent factors can be clustered to obtain a new set of regions that is more aligned with the response variables than the original regions that were defined a priori from the ecology domain.

National variability in provision of health services for major long-term conditions in New Zealand (a report from the ABCC NZ study).

PubMed

Connolly, Martin J; Kenealy, Timothy; Barber, P Alan; Carswell, Peter; Clinton, Janet; Dyall, Lorna; Devlin, Gerard; Doughty, Robert N; Kerse, Ngaire; Kolbe, John; Lawrenson, Ross; Moffitt, Allan; Sheridan, Nicolette

2011-10-14

Chronic illness is the leading cause of morbidity, mortality, and inequitable health outcomes in New Zealand. The ABCCNZ Stocktake aimed to identify extent of long-term conditions management evidence-based practices in stroke, cardiovascular disease, chronic obstructive pulmonary disease and congestive heart failure in New Zealand's District Health Boards (DHBs). Eleven 'dimensions' of care for long-term conditions, identified by literature review and confirmed at workshops with long-term conditions professionals, formed the basis of the Stocktake of all 21 DHBs. It comprised two questionnaires: a generic component capturing perceptions of practice; and a disease-specific component assessing service provision. Fifteen DHBs completed all or parts of the questionnaires. Data accrual was completed in July 2008. Although most DHBs had developed long-term conditions management strategies to a moderate degree, there was considerable variability of practice between DHBs. DHBs thought their PHOs had developed strategies in some areas to a low to moderate level, though cardiovascular disease provision rated more highly. Regarding disease-specific services, larger DHBs had greater long-term conditions management provision not only of tertiary services, but of standard care, leadership, self-management, case-management, and audit. There is considerable variability in perceptions of long-term conditions management service provision across DHBs. In many instances variability in actual disease-specific service provision appears to relate to DHB size.

Assessing groundwater vulnerability to agrichemical contamination in the Midwest US

USGS Publications Warehouse

Burkart, M.R.; Kolpin, D.W.; James, D.E.

1999-01-01

Agrichemicals (herbicides and nitrate) are significant sources of diffuse pollution to groundwater. Indirect methods are needed to assess the potential for groundwater contamination by diffuse sources because groundwater monitoring is too costly to adequately define the geographic extent of contamination at a regional or national scale. This paper presents examples of the application of statistical, overlay and index, and process-based modeling methods for groundwater vulnerability assessments to a variety of data from the Midwest U.S. The principles for vulnerability assessment include both intrinsic (pedologic, climatologic, and hydrogeologic factors) and specific (contaminant and other anthropogenic factors) vulnerability of a location. Statistical methods use the frequency of contaminant occurrence, contaminant concentration, or contamination probability as a response variable. Statistical assessments are useful for defining the relations among explanatory and response variables whether they define intrinsic or specific vulnerability. Multivariate statistical analyses are useful for ranking variables critical to estimating water quality responses of interest. Overlay and index methods involve intersecting maps of intrinsic and specific vulnerability properties and indexing the variables by applying appropriate weights. Deterministic models use process-based equations to simulate contaminant transport and are distinguished from the other methods in their potential to predict contaminant transport in both space and time. An example of a one-dimensional leaching model linked to a geographic information system (GIS) to define a regional metamodel for contamination in the Midwest is included.

Determination of colonoscopy indication from administrative claims data.

PubMed

Ko, Cynthia W; Dominitz, Jason A; Neradilek, Moni; Polissar, Nayak; Green, Pam; Kreuter, William; Baldwin, Laura-Mae

2014-04-01

Colonoscopy outcomes, such as polyp detection or complication rates, may differ by procedure indication. To develop methods to classify colonoscopy indications from administrative data, facilitating study of colonoscopy quality and outcomes. We linked 14,844 colonoscopy reports from the Clinical Outcomes Research Initiative, a national repository of endoscopic reports, to the corresponding Medicare Carrier and Outpatient File claims. Colonoscopy indication was determined from the procedure reports. We developed algorithms using classification and regression trees and linear discriminant analysis (LDA) to classify colonoscopy indication. Predictor variables included ICD-9CM and CPT/HCPCS codes present on the colonoscopy claim or in the 12 months prior, patient demographics, and site of colonoscopy service. Algorithms were developed on a training set of 7515 procedures, then validated using a test set of 7329 procedures. Sensitivity was lowest for identifying average-risk screening colonoscopies, varying between 55% and 86% for the different algorithms, but specificity for this indication was consistently over 95%. Sensitivity for diagnostic colonoscopy varied between 77% and 89%, with specificity between 55% and 87%. Algorithms with classification and regression trees with 7 variables or LDA with 10 variables had similar overall accuracy, and generally lower accuracy than the algorithm using LDA with 30 variables. Algorithms using Medicare claims data have moderate sensitivity and specificity for colonoscopy indication, and will be useful for studying colonoscopy quality in this population. Further validation may be needed before use in alternative populations.

Sigh rate and respiratory variability during mental load and sustained attention.

PubMed

Vlemincx, Elke; Taelman, Joachim; De Peuter, Steven; Van Diest, Ilse; Van den Bergh, Omer

2011-01-01

Spontaneous breathing consists of substantial correlated variability: Parameters characterizing a breath are correlated with parameters characterizing previous and future breaths. On the basis of dynamic system theory, negative emotion states are predicted to reduce correlated variability whereas sustained attention is expected to reduce total respiratory variability. Both are predicted to evoke sighing. To test this, respiratory variability and sighing were assessed during a baseline, stressful mental arithmetic task, nonstressful sustained attention task, and recovery in between tasks. For respiration rate (excluding sighs), reduced total variability was found during the attention task, whereas correlated variation was reduced during mental load. Sigh rate increased during mental load and during recovery from the attention task. It is concluded that mental load and task-related attention show specific patterns in respiratory variability and sigh rate. Copyright © 2010 Society for Psychophysiological Research.

Difficulties with Regression Analysis of Age-Adjusted Rates.

DTIC Science & Technology

1982-09-01

variables used in those analyses, such as death rates in various states, have been age adjusted, whereas the predictor variables have not been age adjusted...The use of crude state death rates as the outcome variable with crude covariates and age as predictors can avoid the problem, at least under some...should be regressed on age-adjusted exposure Z+B+ Although age-specific death rates , Yas+’ may be available, it is often difficult to obtain age

Large-Scale Effects of Timber Harvesting on Stream Systems in the Ouachita Mountains, Arkansas, USA

NASA Astrophysics Data System (ADS)

Williams, Lance R.; Taylor, Christopher M.; Warren, Melvin L., Jr.; Clingenpeel, J. Alan

2002-01-01

Using Basin Area Stream Survey (BASS) data from the United States Forest Service, we evaluated how timber harvesting influenced patterns of variation in physical stream features and regional fish and macroinvertebrate assemblages. Data were collected for three years (1990-1992) from six hydrologically variable streams in the Ouachita Mountains, Arkansas, USA that were paired by management regime within three drainage basins. Specifically, we used multivariate techniques to partition variability in assemblage structure (taxonomic and trophic) that could be explained by timber harvesting, drainage basin differences, year-to-year variability, and their shared variance components. Most of the variation in fish assemblages was explained by drainage basin differences, and both basin and year-of-sampling influenced macroinvertebrate assemblages. All three factors modeled, including interactions between drainage basins and timber harvesting, influenced variability in physical stream features. Interactions between timber harvesting and drainage basins indicated that differences in physical stream features were important in determining the effects of logging within a basin. The lack of a logging effect on the biota contradicts predictions for these small, hydrologically variable streams. We believe this pattern is related to the large scale of this study and the high levels of natural variability in the streams. Alternatively, there may be time-specific effects we were unable to detect with our sampling design and analyses.

Constrained Stochastic Extended Redundancy Analysis.

PubMed

DeSarbo, Wayne S; Hwang, Heungsun; Stadler Blank, Ashley; Kappe, Eelco

2015-06-01

We devise a new statistical methodology called constrained stochastic extended redundancy analysis (CSERA) to examine the comparative impact of various conceptual factors, or drivers, as well as the specific predictor variables that contribute to each driver on designated dependent variable(s). The technical details of the proposed methodology, the maximum likelihood estimation algorithm, and model selection heuristics are discussed. A sports marketing consumer psychology application is provided in a Major League Baseball (MLB) context where the effects of six conceptual drivers of game attendance and their defining predictor variables are estimated. Results compare favorably to those obtained using traditional extended redundancy analysis (ERA).

Perceived patient control over personal health information in the presence of context-specific concerns

NASA Astrophysics Data System (ADS)

Nanayakkara, Prabhashi A.

Information privacy issues have plagued the world of electronic media since its inception. This research focused mainly on factors that increase or decrease perceived patient control over personal health information (CTL) in the presence of context-specific concerns. Control agency theory was used for the paper's theoretical contributions. Personal and proxy control agencies acted as the independent variables, and context-specific concerns for information privacy (CFIP) were used as the moderator between proxy control agency, healthcare provider, and CTL. Demographic data and three control variables-- the desire for information control, privacy experience, and trust propensity--were also included in the model to gauge the contribution to CTL from external factors. Only personal control agency and desire for information control were found to impact CTL.

Cerebrospinal fluid anti-Epstein-Barr virus specific oligoclonal IgM and IgG bands in patients with clinically isolated and Guillain-Barré syndrome.

PubMed

Ferraro, Diana; Galli, Veronica; Simone, Anna Maria; Bedin, Roberta; Vitetta, Francesca; Merelli, Elisa; Nichelli, Paolo Frigio; Sola, Patrizia

2017-04-01

Epstein-Barr virus (EBV) has been implicated in multiple sclerosis (MS) pathogenesis. We aimed to assess the frequency of EBV-specific IgG and IgM oligoclonal bands (OCB) in cerebrospinal fluid (CSF) of 50 patients with clinically isolated syndrome (CIS) and in 27 controls with Guillain-Barré syndrome (GBS). Furthermore, we assessed correlations between the presence of OCB and CIS patients' CSF, MRI, and clinical variables. There was no difference in the proportion of CIS and GB patients with positivity for anti-EBV-specific IgG/IgM OCB. There were no correlations between OCB and analyzed variables, nor were they predictive of a higher disability at 3 years.

Estimating, Testing, and Comparing Specific Effects in Structural Equation Models: The Phantom Model Approach

ERIC Educational Resources Information Center

Macho, Siegfried; Ledermann, Thomas

2011-01-01

The phantom model approach for estimating, testing, and comparing specific effects within structural equation models (SEMs) is presented. The rationale underlying this novel method consists in representing the specific effect to be assessed as a total effect within a separate latent variable model, the phantom model that is added to the main…

Site-specific nutrient management systems

USDA-ARS?s Scientific Manuscript database

Site-specific nutrient management systems were created to manage for spatial and temporal variability in biophysical factors that determine the availability and demand of crop nutrients. These systems differ among geographical regions in the information utilized and way they operate to accomplish th...

Things that go bump in the light - On the optical specification of contact severity

NASA Technical Reports Server (NTRS)

Kaiser, Mary K.; Phatak, Anil V.

1993-01-01

Psychologists are intrigued with the idea that optical variables can specify not only the time until an object impacts an observer but also the severity of the impact. However, the mapping between the optical variables and the kinematic variables has been misstated, erroneously implying that there exist critical values of the optical variables used for locomotion and control. In this commentary, the mathematical relationship between the optical and kinematic variables is reexamined and the erroneous assumptions that have led to the proposal of critical values are shown. Also examined are the empirical data on deceleration to approach to assess whether the proposed optical variables are likely candidates for control strategies. Finally, problems associated with numerical approximations to dynamic systems, particularly when analytic solutions exist, are discussed.

Coupled Ethical–Epistemic Analysis of Public Health Research and Practice: Categorizing Variables to Improve Population Health and Equity

PubMed Central

Katikireddi, S. Vittal; Valles, Sean A

2015-01-01

The categorization of variables can stigmatize populations, which is ethically problematic and threatens the central purpose of public health: to improve population health and reduce health inequities. How social variables (e.g., behavioral risks for HIV) are categorized can reinforce stigma and cause unintended harms to the populations practitioners and researchers strive to serve. Although debates about the validity or ethical consequences of epidemiological variables are familiar for specific variables (e.g., ethnicity), these issues apply more widely. We argue that these tensions and debates regarding epidemiological variables should be analyzed simultaneously as ethical and epistemic challenges. We describe a framework derived from the philosophy of science that may be usefully applied to public health, and we illustrate its application. PMID:25393193

Phospholipase C-β1 and β4 Contribute to Non-Genetic Cell-to-Cell Variability in Histamine-Induced Calcium Signals in HeLa Cells

PubMed Central

Ishida, Sachiko; Matsu-ura, Toru; Fukami, Kiyoko; Michikawa, Takayuki; Mikoshiba, Katsuhiko

2014-01-01

A uniform extracellular stimulus triggers cell-specific patterns of Ca2+ signals, even in genetically identical cell populations. However, the underlying mechanism that generates the cell-to-cell variability remains unknown. We monitored cytosolic inositol 1,4,5-trisphosphate (IP3) concentration changes using a fluorescent IP3 sensor in single HeLa cells showing different patterns of histamine-induced Ca2+ oscillations in terms of the time constant of Ca2+ spike amplitude decay and the Ca2+ oscillation frequency. HeLa cells stimulated with histamine exhibited a considerable variation in the temporal pattern of Ca2+ signals and we found that there were cell-specific IP3 dynamics depending on the patterns of Ca2+ signals. RT-PCR and western blot analyses showed that phospholipase C (PLC)-β1, -β3, -β4, -γ1, -δ3 and -ε were expressed at relatively high levels in HeLa cells. Small interfering RNA-mediated silencing of PLC isozymes revealed that PLC-β1 and PLC-β4 were specifically involved in the histamine-induced IP3 increases in HeLa cells. Modulation of IP3 dynamics by knockdown or overexpression of the isozymes PLC-β1 and PLC-β4 resulted in specific changes in the characteristics of Ca2+ oscillations, such as the time constant of the temporal changes in the Ca2+ spike amplitude and the Ca2+ oscillation frequency, within the range of the cell-to-cell variability found in wild-type cell populations. These findings indicate that the heterogeneity in the process of IP3 production, rather than IP3-induced Ca2+ release, can cause cell-to-cell variability in the patterns of Ca2+ signals and that PLC-β1 and PLC-β4 contribute to generate cell-specific Ca2+ signals evoked by G protein-coupled receptor stimulation. PMID:24475116

Salivary aldehyde dehydrogenase - temporal and population variability, correlations with drinking and smoking habits and activity towards aldehydes contained in food.

PubMed

Giebułtowicz, Joanna; Dziadek, Marta; Wroczyński, Piotr; Woźnicka, Katarzyna; Wojno, Barbara; Pietrzak, Monika; Wierzchowski, Jacek

2010-01-01

Fluorimetric method based on oxidation of the fluorogenic 6-methoxy-2-naphthaldehyde was applied to evaluate temporal and population variability of the specific activity of salivary aldehyde dehydrogenase (ALDH) and the degree of its inactivation in healthy human population. Analyzed was also its dependence on drinking and smoking habits, coffee consumption, and its sensitivity to N-acetylcysteine. Both the specific activity of salivary ALDH and the degree of its inactivation were highly variable during the day, with the highest activities recorded in the morning hours. The activities were also highly variable both intra- and interpersonally, and negatively correlated with age, and this correlation was stronger for the subgroup of volunteers declaring abstinence from alcohol and tobacco. Moderately positive correlations of salivary ALDH specific activity with alcohol consumption and tobacco smoking were also recorded (r(s) ~0.27; p=0.004 and r(s) =0.30; p=0.001, respectively). Moderate coffee consumption correlated positively with the inactivation of salivary ALDH, particularly in the subgroup of non-drinking and non-smoking volunteers. It was found that mechanical stimulation of the saliva flow increases the specific activity of salivary ALDH. The specific activity of the salivary ALDH was strongly and positively correlated with that of superoxide dismutase, and somewhat less with salivary peroxidase. The antioxidant-containing drug N-acetylcysteine increased activity of salivary ALDH presumably by preventing its inactivation in the oral cavity. Some food-related aldehydes, mainly cinnamic aldehyde and anisaldehyde, were excellent substrates of the salivary ALDH3A1 enzyme, while alkenals, particularly those with short chain, were characterized by lower affinity towards this enzyme but high catalytic constants. The protective role of salivary ALDH against aldehydes in food and those found in the cigarette smoke is discussed, as well as its participation in diminishing the effects of alcohol- and smoking-related oxidative stress.

Tree-, stand- and site-specific controls on landscape-scale patterns of transpiration

NASA Astrophysics Data System (ADS)

Hassler, Sibylle; Markus, Weiler; Theresa, Blume

2017-04-01

Transpiration is a key process in the hydrological cycle and a sound understanding and quantification of transpiration and its spatial variability is essential for management decisions as well as for improving the parameterisation of hydrological and soil-vegetation-atmosphere transfer models. For individual trees, transpiration is commonly estimated by measuring sap flow. Besides evaporative demand and water availability, tree-specific characteristics such as species, size or social status control sap flow amounts of individual trees. Within forest stands, properties such as species composition, basal area or stand density additionally affect sap flow, for example via competition mechanisms. Finally, sap flow patterns might also be influenced by landscape-scale characteristics such as geology, slope position or aspect because they affect water and energy availability; however, little is known about the dynamic interplay of these controls. We studied the relative importance of various tree-, stand- and site-specific characteristics with multiple linear regression models to explain the variability of sap velocity measurements in 61 beech and oak trees, located at 24 sites spread over a 290 km2-catchment in Luxembourg. For each of 132 consecutive days of the growing season of 2014 we modelled the daily sap velocities of these 61 trees and determined the importance of the different predictors. Results indicate that a combination of tree-, stand- and site-specific factors controls sap velocity patterns in the landscape, namely tree species, tree diameter, the stand density, geology and aspect. Compared to these predictors, spatial variability of atmospheric demand and soil moisture explains only a small fraction of the variability in the daily datasets. However, the temporal dynamics of the explanatory power of the tree-specific characteristics, especially species, are correlated to the temporal dynamics of potential evaporation. Thus, transpiration estimates at the landscape scale would benefit from not only considering hydro-meteorological drivers, but also including tree, stand and site characteristics in order to improve the spatial representation of transpiration for hydrological and soil-vegetation-atmosphere transfer models.

CAN'T MISS--conquer any number task by making important statistics simple. Part 1. Types of variables, mean, median, variance, and standard deviation.

PubMed

Hansen, John P

2003-01-01

Healthcare quality improvement professionals need to understand and use inferential statistics to interpret sample data from their organizations. In quality improvement and healthcare research studies all the data from a population often are not available, so investigators take samples and make inferences about the population by using inferential statistics. This three-part series will give readers an understanding of the concepts of inferential statistics as well as the specific tools for calculating confidence intervals for samples of data. This article, Part 1, presents basic information about data including a classification system that describes the four major types of variables: continuous quantitative variable, discrete quantitative variable, ordinal categorical variable (including the binomial variable), and nominal categorical variable. A histogram is a graph that displays the frequency distribution for a continuous variable. The article also demonstrates how to calculate the mean, median, standard deviation, and variance for a continuous variable.

Example-Based Learning: Exploring the Use of Matrices and Problem Variability

ERIC Educational Resources Information Center

Hancock-Niemic, Mary A.; Lin, Lijia; Atkinson, Robert K.; Renkl, Alexander; Wittwer, Joerg

2016-01-01

The purpose of the study was to investigate the efficacy of using faded worked examples presented in matrices with problem structure variability to enhance learners' ability to recognize the underlying structure of the problems. Specifically, this study compared the effects of matrix-format versus linear-format faded worked examples combined with…

Feelings of Existential Fulfilment and Burnout among Secondary School Teachers

ERIC Educational Resources Information Center

Loonstra, Bert; Brouwers, Andre; Tomic, Welko

2009-01-01

Teacher burnout is recognized as a serious problem. In research it has been related to many person-specific variables; one of these, the variable of existential fulfilment, has received very little attention thus far. The present study focuses on the relationship between existential fulfilment and burnout among secondary school teachers in the…

Variability in Written Japanese: Towards a Sociolinguistics of Script Choice.

ERIC Educational Resources Information Center

Smith, Janet S.; Schmidt, David L.

1996-01-01

Tests widely-held associations among script types, genres, writers, and target readers via statistical analysis in popular Japanese fiction. Subjects texts to lexical analysis to see whether choice of vocabulary can account for variability in script selection. Finds that Japanese writers fashion their script type choices to specific contexts, as…

Language Experience Interviews: What Can They Tell Us about Individual Differences?

ERIC Educational Resources Information Center

Polat, Brittany

2013-01-01

While language learners and teachers have long known that individual differences (IDs) among students result in differential learning, we still do not know how traditional ID variables interact or the specific impact each one has on language learning. The present study proposes that instead of looking at isolated variables, researchers should…

Projecting county pulpwood production with historical production and macro-economic variables

Treesearch

Consuelo Brandeis; Dayton M. Lambert

2014-01-01

We explored forecasting of county roundwood pulpwood produc-tion with county-vector autoregressive (CVAR) and spatial panelvector autoregressive (SPVAR) methods. The analysis used timberproducts output data for the state of Florida, together with a set ofmacro-economic variables. Overall, we found the SPVAR specifica-tion produced forecasts with lower error rates...

Delphi-Discrepancy Evaluation: A Model for the Quality Control of Federal, State, and Locally Mandated Programs.

ERIC Educational Resources Information Center

Sirois, Herman A.; Iwanick, Edward F.

Legally mandated educational programs often lack specificity and guidelines for such programs are often vague and subject to considerable variability in interpretation. This situation presents perennial problems for evaluators. Few evaluation models have the flexibility for dealing with this ambiguity and variability while at the same time…

Multivariate geomorphic analysis of forest streams: Implications for assessment of land use impacts on channel condition

Treesearch

Richard. D. Wood-Smith; John M. Buffington

1996-01-01

Multivariate statistical analyses of geomorphic variables from 23 forest stream reaches in southeast Alaska result in successful discrimination between pristine streams and those disturbed by land management, specifically timber harvesting and associated road building. Results of discriminant function analysis indicate that a three-variable model discriminates 10...

Impacts of climate change and variability on transportation systems and infrastructure : Gulf Coast study, phase 2 : task 2 : climate variability and change in Mobile, Alabama.

DOT National Transportation Integrated Search

2012-09-01

Despite increasing confidence in global climate change projections in recent years, projections of : climate effects at local scales remains scarce. Location-specific risks to transportation systems : imposed by changes in climate are not yet well kn...

Kinematic Constraints Associated with the Acquisition of Overarm Throwing Part II: Upper Extremity Actions

ERIC Educational Resources Information Center

Stodden, David F.; Langendorfer, Stephen J.; Fleisig, Glenn S.; Andrews, James R.

2006-01-01

The purposes of this study were to: (a) examine the differences within 11 specific kinematic variables and an outcome measure (ball velocity) associated with component developmental levels of humerus and forearm action (Roberton & Halverson, 1984), and (b) if the differences in kinematic variables were significantly associated with the differences…

Kinematic Constraints Associated with the Acquisition of Overarm Throwing Part I: Step and Trunk Actions

ERIC Educational Resources Information Center

Stodden, David F.; Langendorfer, Stephen J.; Fleisig, Glenn S.; Andrews, James R.

2006-01-01

The purposes of this study were to: (a) examine differences within specific kinematic variables and ball velocity associated with developmental component levels of step and trunk action (Roberton & Halverson, 1984), and (b) if the differences in kinematic variables were significantly associated with the differences in component levels, determine…

Identification of Student- and Teacher-Level Variables in Modeling Variation of Mathematics Achievement Data

ERIC Educational Resources Information Center

Tarr, James E.; Ross, Daniel J.; McNaught, Melissa D.; Chavez, Oscar; Grouws, Douglas A.; Reys, Robert E.; Sears, Ruthmae; Taylan, R. Didem

2010-01-01

The Comparing Options in Secondary Mathematics: Investigating Curriculum (COSMIC) project is a longitudinal study of student learning from two types of mathematics curricula: integrated and subject-specific. Previous large-scale research studies such as the National Assessment of Educational Progress (NAEP) indicate that numerous variables are…

Increased Intraindividual Variability Is a Marker of ADHD but Also of Dyslexia: A Study on Handwriting

ERIC Educational Resources Information Center

Borella, Erika; Chicherio, Christian; Re, Anna Maria; Sensini, Vanessa; Cornoldi, Cesare

2011-01-01

It has been suggested that intraindividual variability (IIV) in neuropsychological tasks may be a specific characteristic of Attention-Deficit Hyperactivity Disorder (ADHD), but previous research has not thoroughly examined whether IIV also concerns academic performance or other types of developmental disabilities. The present study investigates…

Students' Self-Regulation for Interaction with Others in Online Learning Environments

ERIC Educational Resources Information Center

Cho, Moon-Heum; Kim, B. Joon

2013-01-01

The purpose of this study was to explore variables explaining students' self-regulation (SR) for interaction with others, specifically peers and instructors, in online learning environments. A total of 407 students participated in the study. With hierarchical regression model (HRM), several variables were regressed on students' SR for interaction…

The microcomputer scientific software series 5: the BIOMASS user's guide.

Treesearch

George E. Host; Stephen C. Westin; William G. Cole; Kurt S. Pregitzer

1989-01-01

BIOMASS is an interactive microcomputer program that uses allometric regression equations to calculate aboveground biomass of common tree species of the Lake States. The equations are species-specific and most use both diameter and height as independent variables. The program accommodates fixed area and variable radius sample designs and produces both individual tree...

Current status and future directions of precision aerial application for site-specific crop management in the USA

USDA-ARS?s Scientific Manuscript database

The first variable-rate aerial application system was developed about a decade ago in the USA and since then, aerial application has benefitted from these technologies. Many areas of the United States rely on readily available agricultural airplanes or helicopters for pest management, and variable-...

Assessment of Adolescent Perceptions on Parental Attitudes on Different Variables

ERIC Educational Resources Information Center

Ersoy, Evren

2015-01-01

The purpose of this study is to examine secondary school student perceptions of parental attitudes with regards to specific variables. Independent samples t test for parametric distributions and one-way variance analysis (ANOVA) was used for analyzing the data, when the ANOVA analyses were significant Scheffe test was conducted on homogeneous…

Mixture Distribution Latent State-Trait Analysis: Basic Ideas and Applications

ERIC Educational Resources Information Center

Courvoisier, Delphine S.; Eid, Michael; Nussbeck, Fridtjof W.

2007-01-01

Extensions of latent state-trait models for continuous observed variables to mixture latent state-trait models with and without covariates of change are presented that can separate individuals differing in their occasion-specific variability. An empirical application to the repeated measurement of mood states (N = 501) revealed that a model with 2…

Continuous water-quality monitoring and regression analysis to estimate constituent concentrations and loads in the Red River of the North at Fargo and Grand Forks, North Dakota, 2003-12

USGS Publications Warehouse

Galloway, Joel M.

2014-01-01

The Red River of the North (hereafter referred to as “Red River”) Basin is an important hydrologic region where water is a valuable resource for the region’s economy. Continuous water-quality monitors have been operated by the U.S. Geological Survey, in cooperation with the North Dakota Department of Health, Minnesota Pollution Control Agency, City of Fargo, City of Moorhead, City of Grand Forks, and City of East Grand Forks at the Red River at Fargo, North Dakota, from 2003 through 2012 and at Grand Forks, N.Dak., from 2007 through 2012. The purpose of the monitoring was to provide a better understanding of the water-quality dynamics of the Red River and provide a way to track changes in water quality. Regression equations were developed that can be used to estimate concentrations and loads for dissolved solids, sulfate, chloride, nitrate plus nitrite, total phosphorus, and suspended sediment using explanatory variables such as streamflow, specific conductance, and turbidity. Specific conductance was determined to be a significant explanatory variable for estimating dissolved solids concentrations at the Red River at Fargo and Grand Forks. The regression equations provided good relations between dissolved solid concentrations and specific conductance for the Red River at Fargo and at Grand Forks, with adjusted coefficients of determination of 0.99 and 0.98, respectively. Specific conductance, log-transformed streamflow, and a seasonal component were statistically significant explanatory variables for estimating sulfate in the Red River at Fargo and Grand Forks. Regression equations provided good relations between sulfate concentrations and the explanatory variables, with adjusted coefficients of determination of 0.94 and 0.89, respectively. For the Red River at Fargo and Grand Forks, specific conductance, streamflow, and a seasonal component were statistically significant explanatory variables for estimating chloride. For the Red River at Grand Forks, a time component also was a statistically significant explanatory variable for estimating chloride. The regression equations for chloride at the Red River at Fargo provided a fair relation between chloride concentrations and the explanatory variables, with an adjusted coefficient of determination of 0.66 and the equation for the Red River at Grand Forks provided a relatively good relation between chloride concentrations and the explanatory variables, with an adjusted coefficient of determination of 0.77. Turbidity and streamflow were statistically significant explanatory variables for estimating nitrate plus nitrite concentrations at the Red River at Fargo and turbidity was the only statistically significant explanatory variable for estimating nitrate plus nitrite concentrations at Grand Forks. The regression equation for the Red River at Fargo provided a relatively poor relation between nitrate plus nitrite concentrations, turbidity, and streamflow, with an adjusted coefficient of determination of 0.46. The regression equation for the Red River at Grand Forks provided a fair relation between nitrate plus nitrite concentrations and turbidity, with an adjusted coefficient of determination of 0.73. Some of the variability that was not explained by the equations might be attributed to different sources contributing nitrates to the stream at different times. Turbidity, streamflow, and a seasonal component were statistically significant explanatory variables for estimating total phosphorus at the Red River at Fargo and Grand Forks. The regression equation for the Red River at Fargo provided a relatively fair relation between total phosphorus concentrations, turbidity, streamflow, and season, with an adjusted coefficient of determination of 0.74. The regression equation for the Red River at Grand Forks provided a good relation between total phosphorus concentrations, turbidity, streamflow, and season, with an adjusted coefficient of determination of 0.87. For the Red River at Fargo, turbidity and streamflow were statistically significant explanatory variables for estimating suspended-sediment concentrations. For the Red River at Grand Forks, turbidity was the only statistically significant explanatory variable for estimating suspended-sediment concentration. The regression equation at the Red River at Fargo provided a good relation between suspended-sediment concentration, turbidity, and streamflow, with an adjusted coefficient of determination of 0.95. The regression equation for the Red River at Grand Forks provided a good relation between suspended-sediment concentration and turbidity, with an adjusted coefficient of determination of 0.96.

Pathogen prevalence predicts human cross-cultural variability in individualism/collectivism.

PubMed

Fincher, Corey L; Thornhill, Randy; Murray, Damian R; Schaller, Mark

2008-06-07

Pathogenic diseases impose selection pressures on the social behaviour of host populations. In humans (Homo sapiens), many psychological phenomena appear to serve an antipathogen defence function. One broad implication is the existence of cross-cultural differences in human cognition and behaviour contingent upon the relative presence of pathogens in the local ecology. We focus specifically on one fundamental cultural variable: differences in individualistic versus collectivist values. We suggest that specific behavioural manifestations of collectivism (e.g. ethnocentrism, conformity) can inhibit the transmission of pathogens; and so we hypothesize that collectivism (compared with individualism) will more often characterize cultures in regions that have historically had higher prevalence of pathogens. Drawing on epidemiological data and the findings of worldwide cross-national surveys of individualism/collectivism, our results support this hypothesis: the regional prevalence of pathogens has a strong positive correlation with cultural indicators of collectivism and a strong negative correlation with individualism. The correlations remain significant even when controlling for potential confounding variables. These results help to explain the origin of a paradigmatic cross-cultural difference, and reveal previously undocumented consequences of pathogenic diseases on the variable nature of human societies.

Selection of specific protein binders for pre-defined targets from an optimized library of artificial helicoidal repeat proteins (alphaRep).

PubMed

Guellouz, Asma; Valerio-Lepiniec, Marie; Urvoas, Agathe; Chevrel, Anne; Graille, Marc; Fourati-Kammoun, Zaineb; Desmadril, Michel; van Tilbeurgh, Herman; Minard, Philippe

2013-01-01

We previously designed a new family of artificial proteins named αRep based on a subgroup of thermostable helicoidal HEAT-like repeats. We have now assembled a large optimized αRep library. In this library, the side chains at each variable position are not fully randomized but instead encoded by a distribution of codons based on the natural frequency of side chains of the natural repeats family. The library construction is based on a polymerization of micro-genes and therefore results in a distribution of proteins with a variable number of repeats. We improved the library construction process using a "filtration" procedure to retain only fully coding modules that were recombined to recreate sequence diversity. The final library named Lib2.1 contains 1.7×10(9) independent clones. Here, we used phage display to select, from the previously described library or from the new library, new specific αRep proteins binding to four different non-related predefined protein targets. Specific binders were selected in each case. The results show that binders with various sizes are selected including relatively long sequences, with up to 7 repeats. ITC-measured affinities vary with Kd values ranging from micromolar to nanomolar ranges. The formation of complexes is associated with a significant thermal stabilization of the bound target protein. The crystal structures of two complexes between αRep and their cognate targets were solved and show that the new interfaces are established by the variable surfaces of the repeated modules, as well by the variable N-cap residues. These results suggest that αRep library is a new and versatile source of tight and specific binding proteins with favorable biophysical properties.

Cost-effectiveness analysis using data from multinational trials: The use of bivariate hierarchical modelling

PubMed Central

Manca, Andrea; Lambert, Paul C; Sculpher, Mark; Rice, Nigel

2008-01-01

Healthcare cost-effectiveness analysis (CEA) often uses individual patient data (IPD) from multinational randomised controlled trials. Although designed to account for between-patient sampling variability in the clinical and economic data, standard analytical approaches to CEA ignore the presence of between-location variability in the study results. This is a restrictive limitation given that countries often differ in factors that could affect the results of CEAs, such as the availability of healthcare resources, their unit costs, clinical practice, and patient case-mix. We advocate the use of Bayesian bivariate hierarchical modelling to analyse multinational cost-effectiveness data. This analytical framework explicitly recognises that patient-level costs and outcomes are nested within countries. Using real life data, we illustrate how the proposed methods can be applied to obtain (a) more appropriate estimates of overall cost-effectiveness and associated measure of sampling uncertainty compared to standard CEA; and (b) country-specific cost-effectiveness estimates which can be used to assess the between-location variability of the study results, while controlling for differences in country-specific and patient-specific characteristics. It is demonstrated that results from standard CEA using IPD from multinational trials display a large degree of variability across the 17 countries included in the analysis, producing potentially misleading results. In contrast, ‘shrinkage estimates’ obtained from the modelling approach proposed here facilitate the appropriate quantification of country-specific cost-effectiveness estimates, while weighting the results based on the level of information available within each country. We suggest that the methods presented here represent a general framework for the analysis of economic data collected from different locations. PMID:17641141

Generation and characterization of ABT-981, a dual variable domain immunoglobulin (DVD-Ig(TM)) molecule that specifically and potently neutralizes both IL-1α and IL-1β.

PubMed

Lacy, Susan E; Wu, Chengbin; Ambrosi, Dominic J; Hsieh, Chung-Ming; Bose, Sahana; Miller, Renee; Conlon, Donna M; Tarcsa, Edit; Chari, Ravi; Ghayur, Tariq; Kamath, Rajesh V

2015-01-01

Interleukin-1 (IL-1) cytokines such as IL-1α, IL-1β, and IL-1Ra contribute to immune regulation and inflammatory processes by exerting a wide range of cellular responses, including expression of cytokines and chemokines, matrix metalloproteinases, and nitric oxide synthetase. IL-1α and IL-1β bind to IL-1R1 complexed to the IL-1 receptor accessory protein and induce similar physiological effects. Preclinical and clinical studies provide significant evidence for the role of IL-1 in the pathogenesis of osteoarthritis (OA), including cartilage degradation, bone sclerosis, and synovial proliferation. Here, we describe the generation and characterization of ABT-981, a dual variable domain immunoglobulin (DVD-Ig) of the IgG1/k subtype that specifically and potently neutralizes IL-1α and IL-1β. In ABT-981, the IL-1β variable domain resides in the outer domain of the DVD-Ig, whereas the IL-1α variable domain is located in the inner position. ABT-981 specifically binds to IL-1α and IL-1β, and is physically capable of binding 2 human IL-1α and 2 human IL-1β molecules simultaneously. Single-dose intravenous and subcutaneous pharmacokinetics studies indicate that ABT-981 has a half-life of 8.0 to 10.4 d in cynomolgus monkey and 10.0 to 20.3 d in rodents. ABT-981 exhibits suitable drug-like-properties including affinity, potency, specificity, half-life, and stability for evaluation in human clinical trials. ABT-981 offers an exciting new approach for the treatment of OA, potentially addressing both disease modification and symptom relief as a disease-modifying OA drug.

High Liver Enzyme Concentrations are Associated with Higher Glycemia, but not with Glycemic Variability, in Individuals without Diabetes Mellitus.

PubMed

Noordam, Raymond; Vermond, Debbie; Drenth, Hermijntje; Wijman, Carolien A; Akintola, Abimbola A; van der Kroef, Sabrina; Jansen, Steffy W M; Huurman, Neline C; Schutte, Bianca A M; Beekman, Marian; Slagboom, P Eline; Mooijaart, Simon P; van Heemst, Diana

2017-01-01

Elevated concentrations of liver enzymes have been associated with an increased risk of developing type 2 diabetes mellitus. However, it remains unclear to which specific aspects of diurnal glucose metabolism these associate most. We aimed to investigate the associations between liver enzyme concentrations and 24 h-glucose trajectories in individuals without diabetes mellitus from three independent cohorts. This cross-sectional study included 436 participants without diabetes mellitus from the Active and Healthy Aging Study, the Switchbox Study, and the Growing Old Together Study. Fasting blood samples were drawn to measure gamma-glutamyltransferase (GGT), alanine transaminase, and aspartate transaminase. Measures of glycemia (e.g., nocturnal and diurnal mean glucose levels) and glycemic variability (e.g., mean amplitude of glucose excursions) were derived from continuous glucose monitoring. Analyses were performed separately for the three cohorts; derived estimates were additionally meta-analyzed. After meta-analyses of the three cohorts, elevated liver enzyme concentrations, and specifically elevated GGT concentrations, were associated with higher glycemia. More specific, participants in the highest GGT tertile (GGT ≥37.9 U/L) had a 0.39 mmol/L (95% confidence interval: 0.23, 0.56) higher mean nocturnal glucose (3:00 to 6:00 a.m.) and a 0.23 mmol/L (0.10, 0.36) higher diurnal glucose (6:00 to 0:00 a.m.) than participants in the lowest GGT tertile (GGT <21.23 U/L). However, elevated liver enzyme concentrations were not associated with a higher glycemic variability. Though elevated liver enzyme concentrations did not associate with higher glycemic variability in participants without diabetes mellitus, specifically, elevated GGT concentrations associated with higher glycemia.

Selection of Specific Protein Binders for Pre-Defined Targets from an Optimized Library of Artificial Helicoidal Repeat Proteins (alphaRep)

PubMed Central

Chevrel, Anne; Graille, Marc; Fourati-Kammoun, Zaineb; Desmadril, Michel; van Tilbeurgh, Herman; Minard, Philippe

2013-01-01

We previously designed a new family of artificial proteins named αRep based on a subgroup of thermostable helicoidal HEAT-like repeats. We have now assembled a large optimized αRep library. In this library, the side chains at each variable position are not fully randomized but instead encoded by a distribution of codons based on the natural frequency of side chains of the natural repeats family. The library construction is based on a polymerization of micro-genes and therefore results in a distribution of proteins with a variable number of repeats. We improved the library construction process using a “filtration” procedure to retain only fully coding modules that were recombined to recreate sequence diversity. The final library named Lib2.1 contains 1.7×109 independent clones. Here, we used phage display to select, from the previously described library or from the new library, new specific αRep proteins binding to four different non-related predefined protein targets. Specific binders were selected in each case. The results show that binders with various sizes are selected including relatively long sequences, with up to 7 repeats. ITC-measured affinities vary with Kd values ranging from micromolar to nanomolar ranges. The formation of complexes is associated with a significant thermal stabilization of the bound target protein. The crystal structures of two complexes between αRep and their cognate targets were solved and show that the new interfaces are established by the variable surfaces of the repeated modules, as well by the variable N-cap residues. These results suggest that αRep library is a new and versatile source of tight and specific binding proteins with favorable biophysical properties. PMID:24014183

Single neuropsychological test scores associated with rate of cognitive decline in early Alzheimer disease.

PubMed

Parikh, Mili; Hynan, Linda S; Weiner, Myron F; Lacritz, Laura; Ringe, Wendy; Cullum, C Munro

2014-01-01

Alzheimer disease (AD) characteristically begins with episodic memory impairment followed by other cognitive deficits; however, the course of illness varies, with substantial differences in the rate of cognitive decline. For research and clinical purposes it would be useful to distinguish between persons who will progress slowly from persons who will progress at an average or faster rate. Our objective was to use neurocognitive performance features and disease-specific and health information to determine a predictive model for the rate of cognitive decline in participants with mild AD. We reviewed the records of a series of 96 consecutive participants with mild AD from 1995 to 2011 who had been administered selected neurocognitive tests and clinical measures. Based on Clinical Dementia Rating (CDR) of functional and cognitive decline over 2 years, participants were classified as Faster (n = 45) or Slower (n = 51) Progressors. Stepwise logistic regression analyses using neurocognitive performance features, disease-specific, health, and demographic variables were performed. Neuropsychological scores that distinguished Faster from Slower Progressors included Trail Making Test - A, Digit Symbol, and California Verbal Learning Test (CVLT) Total Learned and Primacy Recall. No disease-specific, health, or demographic variable predicted rate of progression; however, history of heart disease showed a trend. Among the neuropsychological variables, Trail Making Test - A best distinguished Faster from Slower Progressors, with an overall accuracy of 68%. In an omnibus model including neuropsychological, disease-specific, health, and demographic variables, only Trail Making Test - A distinguished between groups. Several neuropsychological performance features were associated with the rate of cognitive decline in mild AD, with baseline Trail Making Test - A performance best separating those who declined at an average or faster rate from those who showed slower progression.

Improving preparedness of farmers to Climate Variability: A case study of Vidarbha region of Maharashtra, India

NASA Astrophysics Data System (ADS)

Swami, D.; Parthasarathy, D.; Dave, P.

2016-12-01

A key objective of the ongoing research is to understand the risk and vulnerability of agriculture and farming communities with respect to multiple climate change attributes, particularly monsoon variability and hydrology such as ground water availability. Climate Variability has always been a feature affecting Indian agriculture but the nature and characteristics of this variability is not well understood. Indian monsoon patterns are highly variable and most of the studies focus on larger domain such as Central India or Western coast (Ghosh et al., 2009) but district level analysis is missing i.e. the linkage between agriculture and climate variables at finer scale has not been investigated comprehensively. For example, Eastern Vidarbha region in Maharashtra is considered as one of the most agriculturally sensitive region in India, where every year a large number of farmers commit suicide. The main reasons for large number of suicides are climate related stressors such as droughts, hail storms, and monsoon variability aggravated with poor socio-economic conditions. Present study has tried to explore the areas in Vidarbha region of Maharashtra where famers and crop productivity, specifically cotton, sorghum, is highly vulnerable to monsoon variability, hydrological and socio-economic variables which are further modelled to determine the maximal contributing factor towards crops and farmers' vulnerability. After analysis using primary and secondary data, it will aid in decision making regarding field operations such as time of sowing, harvesting and irrigation requirements by optimizing the cropping pattern with climatic, hydrological and socio-economic variables. It also suggests the adaptation strategies to farmers regarding different types of cropping and water harvesting practices, optimized dates and timings for harvesting, sowing, water and nutrient requirements of particular crops according to the specific region. Primarily along with secondary analysis captured here can be highly beneficial for the farmers and policy makers while formulating agricultural policies related to climate change.

The sequential hypothesis of sleep function. IV. A correlative analysis of sleep variables in learning and nonlearning rats.

PubMed

Langella, M; Colarieti, L; Ambrosini, M V; Giuditta, A

1992-02-01

Female adult rats were trained for a two-way active avoidance task (4 h), and allowed free sleep (3 h). Control rats (C) were left in their home cages during the acquisition period. Dural electrodes and an intraventricular cannula, implanted one week in advance, were used for EEG recording during the period of sleep and for the injection of [3H]thymidine at the beginning of the training session, respectively. Rats were killed at the end of the sleep period, and the DNA-specific activity was determined in the main brain regions and in liver. Correlations among sleep, behavioral and biochemical variables were assessed using Spearman's nonparametric method. In learning rats (L), the number of avoidances was negatively correlated with SS-W variables, and positively correlated with SS-PS variables (episodes of synchronized sleep followed by wakefulness or paradoxical sleep, respectively) and with PS variables. An inverse pattern of correlations was shown by the number of escapes or freezings. No correlations occurred in rats unable to achieve the learning criterion (NL). In L rats, the specific activity of brain DNA was negatively correlated with SS-W variables and positively correlated with SS-PS variables, while essentially no correlation concerned PS variables. On the other hand, in NL rats, comparable correlations were positive with SS-W variables and negative with SS-PS and PS variables. Few and weak correlations occurred in C rats. The data support a role of SS in brain information processing, as postulated by the sequential hypothesis on the function of sleep. In addition, they suggest that the elimination of nonadaptive memory traces may require several SS-W episodes and a terminal SS-PS episode. During PS episodes, adaptive memory traces cleared of nonadaptive components may be copied in more suitable brain sites.

Understanding the context of healthcare utilization: assessing environmental and provider-related variables in the behavioral model of utilization.

PubMed Central

Phillips, K A; Morrison, K R; Andersen, R; Aday, L A

1998-01-01

OBJECTIVE: The behavioral model of utilization, developed by Andersen, Aday, and others, is one of the most frequently used frameworks for analyzing the factors that are associated with patient utilization of healthcare services. However, the use of the model for examining the context within which utilization occurs-the role of the environment and provider-related factors-has been largely neglected. OBJECTIVE: To conduct a systematic review and analysis to determine if studies of medical care utilization that have used the behavioral model during the last 20 years have included environmental and provider-related variables and the methods used to analyze these variables. We discuss barriers to the use of these contextual variables and potential solutions. DATA SOURCES: The Social Science Citation Index and Science Citation Index. We included all articles from 1975-1995 that cited any of three key articles on the behavioral model, that included all articles that were empirical analyses and studies of formal medical care utilization, and articles that specifically stated their use of the behavioral model (n = 139). STUDY DESIGN: Design was a systematic literature review. DATA ANALYSIS: We used a structured review process to code articles on whether they included contextual variables: (1) environmental variables (characteristics of the healthcare delivery system, external environment, and community-level enabling factors); and (2) provider-related variables (patient factors that may be influenced by providers and provider characteristics that interact with patient characteristics to influence utilization). We also examined the methods used in studies that included contextual variables. PRINCIPAL FINDINGS: Forty-five percent of the studies included environmental variables and 51 percent included provider-related variables. Few studies examined specific measures of the healthcare system or provider characteristics or used methods other than simple regression analysis with hierarchical entry of variables. Only 14 percent of studies analyzed the context of healthcare by including both environmental and provider-related variables as well as using relevant methods. CONCLUSIONS: By assessing whether and how contextual variables are used, we are able to highlight the contributions made by studies using these approaches, to identify variables and methods that have been relatively underused, and to suggest solutions to barriers in using contextual variables. PMID:9685123

Correlation of Metabolic Variables with the Number of ORFs in Human Pathogenic and Phylogenetically Related Non- or Less-Pathogenic Bacteria.

PubMed

Brambila-Tapia, Aniel Jessica Leticia; Poot-Hernández, Augusto Cesar; Garcia-Guevara, Jose Fernando; Rodríguez-Vázquez, Katya

2016-06-01

To date, a few works have performed a correlation of metabolic variables in bacteria; however specific correlations with these variables have not been reported. In this work, we included 36 human pathogenic bacteria and 18 non- or less-pathogenic-related bacteria and obtained all metabolic variables, including enzymes, metabolic pathways, enzymatic steps and specific metabolic pathways, and enzymatic steps of particular metabolic processes, from a reliable metabolic database (KEGG). Then, we correlated the number of the open reading frames (ORF) with these variables and with the proportions of these variables, and we observed a negative correlation with the proportion of enzymes (r = -0.506, p < 0.0001), metabolic pathways (r = -0.871, p < 00.0001), enzymatic reactions (r = -0.749, p < 00.0001), and with the proportions of central metabolism variables as well as a positive correlation with the proportions of multistep reactions (r = 0.650, p < 00.0001) and secondary metabolism variables. The proportion of multifunctional reactions (r: -0.114, p = 0.41) and the proportion of enzymatic steps (r: -0.205, p = 0.14) did not present a significant correlation. These correlations indicate that as the size of a genome (measured in the number of ORFs) increases, the proportion of genes that encode enzymes significantly diminishes (especially those related to central metabolism), suggesting that when essential metabolic pathways are complete, an increase in the number of ORFs does not require a similar increase in the metabolic pathways and enzymes, but only a slight increase is sufficient to cope with a large genome.

Precision of information, sensational information, and self-efficacy information as message-level variables affecting risk perceptions.

PubMed

Dahlstrom, Michael F; Dudo, Anthony; Brossard, Dominique

2012-01-01

Studies that investigate how the mass media cover risk issues often assume that certain characteristics of content are related to specific risk perceptions and behavioral intentions. However, these relationships have seldom been empirically assessed. This study tests the influence of three message-level media variables--risk precision information, sensational information, and self-efficacy information--on perceptions of risk, individual worry, and behavioral intentions toward a pervasive health risk. Results suggest that more precise risk information leads to increased risk perceptions and that the effect of sensational information is moderated by risk precision information. Greater self-efficacy information is associated with greater intention to change behavior, but none of the variables influence individual worry. The results provide a quantitative understanding of how specific characteristics of informational media content can influence individuals' responses to health threats of a global and uncertain nature. © 2011 Society for Risk Analysis.

Variable context Markov chains for HIV protease cleavage site prediction.

PubMed

Oğul, Hasan

2009-06-01

Deciphering the knowledge of HIV protease specificity and developing computational tools for detecting its cleavage sites in protein polypeptide chain are very desirable for designing efficient and specific chemical inhibitors to prevent acquired immunodeficiency syndrome. In this study, we developed a generative model based on a generalization of variable order Markov chains (VOMC) for peptide sequences and adapted the model for prediction of their cleavability by certain proteases. The new method, called variable context Markov chains (VCMC), attempts to identify the context equivalence based on the evolutionary similarities between individual amino acids. It was applied for HIV-1 protease cleavage site prediction problem and shown to outperform existing methods in terms of prediction accuracy on a common dataset. In general, the method is a promising tool for prediction of cleavage sites of all proteases and encouraged to be used for any kind of peptide classification problem as well.

Development of Micro Air Vehicle Technology With In-Flight Adaptive-Wing Structure

NASA Technical Reports Server (NTRS)

Waszak, Martin R. (Technical Monitor); Shkarayev, Sergey; Null, William; Wagner, Matthew

2004-01-01

This is a final report on the research studies, "Development of Micro Air Vehicle Technology with In-Flight Adaptrive-Wing Structure". This project involved the development of variable-camber technology to achieve efficient design of micro air vehicles. Specifically, it focused on the following topics: 1) Low Reynolds number wind tunnel testing of cambered-plate wings. 2) Theoretical performance analysis of micro air vehicles. 3) Design of a variable-camber MAV actuated by micro servos. 4) Test flights of a variable-camber MAV.

Parameter Stability of the Functional–Structural Plant Model GREENLAB as Affected by Variation within Populations, among Seasons and among Growth Stages

PubMed Central

Ma, Yuntao; Li, Baoguo; Zhan, Zhigang; Guo, Yan; Luquet, Delphine; de Reffye, Philippe; Dingkuhn, Michael

2007-01-01

Background and Aims It is increasingly accepted that crop models, if they are to simulate genotype-specific behaviour accurately, should simulate the morphogenetic process generating plant architecture. A functional–structural plant model, GREENLAB, was previously presented and validated for maize. The model is based on a recursive mathematical process, with parameters whose values cannot be measured directly and need to be optimized statistically. This study aims at evaluating the stability of GREENLAB parameters in response to three types of phenotype variability: (1) among individuals from a common population; (2) among populations subjected to different environments (seasons); and (3) among different development stages of the same plants. Methods Five field experiments were conducted in the course of 4 years on irrigated fields near Beijing, China. Detailed observations were conducted throughout the seasons on the dimensions and fresh biomass of all above-ground plant organs for each metamer. Growth stage-specific target files were assembled from the data for GREENLAB parameter optimization. Optimization was conducted for specific developmental stages or the entire growth cycle, for individual plants (replicates), and for different seasons. Parameter stability was evaluated by comparing their CV with that of phenotype observation for the different sources of variability. A reduced data set was developed for easier model parameterization using one season, and validated for the four other seasons. Key Results and Conclusions The analysis of parameter stability among plants sharing the same environment and among populations grown in different environments indicated that the model explains some of the inter-seasonal variability of phenotype (parameters varied less than the phenotype itself), but not inter-plant variability (parameter and phenotype variability were similar). Parameter variability among developmental stages was small, indicating that parameter values were largely development-stage independent. The authors suggest that the high level of parameter stability observed in GREENLAB can be used to conduct comparisons among genotypes and, ultimately, genetic analyses. PMID:17158141

Decoding the spatial signatures of multi-scale climate variability - a climate network perspective

NASA Astrophysics Data System (ADS)

Donner, R. V.; Jajcay, N.; Wiedermann, M.; Ekhtiari, N.; Palus, M.

2017-12-01

During the last years, the application of complex networks as a versatile tool for analyzing complex spatio-temporal data has gained increasing interest. Establishing this approach as a new paradigm in climatology has already provided valuable insights into key spatio-temporal climate variability patterns across scales, including novel perspectives on the dynamics of the El Nino Southern Oscillation or the emergence of extreme precipitation patterns in monsoonal regions. In this work, we report first attempts to employ network analysis for disentangling multi-scale climate variability. Specifically, we introduce the concept of scale-specific climate networks, which comprises a sequence of networks representing the statistical association structure between variations at distinct time scales. For this purpose, we consider global surface air temperature reanalysis data and subject the corresponding time series at each grid point to a complex-valued continuous wavelet transform. From this time-scale decomposition, we obtain three types of signals per grid point and scale - amplitude, phase and reconstructed signal, the statistical similarity of which is then represented by three complex networks associated with each scale. We provide a detailed analysis of the resulting connectivity patterns reflecting the spatial organization of climate variability at each chosen time-scale. Global network characteristics like transitivity or network entropy are shown to provide a new view on the (global average) relevance of different time scales in climate dynamics. Beyond expected trends originating from the increasing smoothness of fluctuations at longer scales, network-based statistics reveal different degrees of fragmentation of spatial co-variability patterns at different scales and zonal shifts among the key players of climate variability from tropically to extra-tropically dominated patterns when moving from inter-annual to decadal scales and beyond. The obtained results demonstrate the potential usefulness of systematically exploiting scale-specific climate networks, whose general patterns are in line with existing climatological knowledge, but provide vast opportunities for further quantifications at local, regional and global scales that are yet to be explored.

The extraction of simple relationships in growth factor-specific multiple-input and multiple-output systems in cell-fate decisions by backward elimination PLS regression.

PubMed

Akimoto, Yuki; Yugi, Katsuyuki; Uda, Shinsuke; Kudo, Takamasa; Komori, Yasunori; Kubota, Hiroyuki; Kuroda, Shinya

2013-01-01

Cells use common signaling molecules for the selective control of downstream gene expression and cell-fate decisions. The relationship between signaling molecules and downstream gene expression and cellular phenotypes is a multiple-input and multiple-output (MIMO) system and is difficult to understand due to its complexity. For example, it has been reported that, in PC12 cells, different types of growth factors activate MAP kinases (MAPKs) including ERK, JNK, and p38, and CREB, for selective protein expression of immediate early genes (IEGs) such as c-FOS, c-JUN, EGR1, JUNB, and FOSB, leading to cell differentiation, proliferation and cell death; however, how multiple-inputs such as MAPKs and CREB regulate multiple-outputs such as expression of the IEGs and cellular phenotypes remains unclear. To address this issue, we employed a statistical method called partial least squares (PLS) regression, which involves a reduction of the dimensionality of the inputs and outputs into latent variables and a linear regression between these latent variables. We measured 1,200 data points for MAPKs and CREB as the inputs and 1,900 data points for IEGs and cellular phenotypes as the outputs, and we constructed the PLS model from these data. The PLS model highlighted the complexity of the MIMO system and growth factor-specific input-output relationships of cell-fate decisions in PC12 cells. Furthermore, to reduce the complexity, we applied a backward elimination method to the PLS regression, in which 60 input variables were reduced to 5 variables, including the phosphorylation of ERK at 10 min, CREB at 5 min and 60 min, AKT at 5 min and JNK at 30 min. The simple PLS model with only 5 input variables demonstrated a predictive ability comparable to that of the full PLS model. The 5 input variables effectively extracted the growth factor-specific simple relationships within the MIMO system in cell-fate decisions in PC12 cells.

Multilayer Joint Gait-Pose Manifolds for Human Gait Motion Modeling.

PubMed

Ding, Meng; Fan, Guolian

2015-11-01

We present new multilayer joint gait-pose manifolds (multilayer JGPMs) for complex human gait motion modeling, where three latent variables are defined jointly in a low-dimensional manifold to represent a variety of body configurations. Specifically, the pose variable (along the pose manifold) denotes a specific stage in a walking cycle; the gait variable (along the gait manifold) represents different walking styles; and the linear scale variable characterizes the maximum stride in a walking cycle. We discuss two kinds of topological priors for coupling the pose and gait manifolds, i.e., cylindrical and toroidal, to examine their effectiveness and suitability for motion modeling. We resort to a topologically-constrained Gaussian process (GP) latent variable model to learn the multilayer JGPMs where two new techniques are introduced to facilitate model learning under limited training data. First is training data diversification that creates a set of simulated motion data with different strides. Second is the topology-aware local learning to speed up model learning by taking advantage of the local topological structure. The experimental results on the Carnegie Mellon University motion capture data demonstrate the advantages of our proposed multilayer models over several existing GP-based motion models in terms of the overall performance of human gait motion modeling.

Strontium isotopes in otoliths of a non-migratory fish (slimy sculpin): Implications for provenance studies

USGS Publications Warehouse

Brennan, Sean R.; Fernandez, Diego P.; Zimmerman, Christian E.; Cerling, Thure E.; Brown, Randy J.; Wooller, Matthew J.

2015-01-01

Heterogeneity in 87Sr/86Sr ratios of river-dissolved strontium (Sr) across geologically diverse environments provides a useful tool for investigating provenance, connectivity and movement patterns of various organisms and materials. Evaluation of site-specific 87Sr/86Sr temporal variability throughout study regions is a prerequisite for provenance research, but the dynamics driving temporal variability are generally system-dependent and not accurately predictable. We used the time-keeping properties of otoliths from non-migratory slimy sculpin (Cottus cognatus) to evaluate multi-scale 87Sr/86Sr temporal variability of river waters throughout the Nushagak River, a large (34,700 km2) remote watershed in Alaska, USA. Slimy sculpin otoliths incorporated site-specific temporal variation at sub-annual resolution and were able to record on the order of 0.0001 changes in the 87Sr/86Sr ratio. 87Sr/86Sr profiles of slimy sculpin collected in tributaries and main-stem channels of the upper watershed indicated that these regions were temporally stable, whereas the Lower Nushagak River exhibited some spatio-teporal variability. This study illustrates how the behavioral ecology of a non-migratory organism can be used to evaluate sub-annual 87Sr/86Sr temporal variability and has broad implications for provenance studies employing this tracer.

Four hundred or more participants needed for stable contingency table estimates of clinical prediction rule performance.

PubMed

Kent, Peter; Boyle, Eleanor; Keating, Jennifer L; Albert, Hanne B; Hartvigsen, Jan

2017-02-01

To quantify variability in the results of statistical analyses based on contingency tables and discuss the implications for the choice of sample size for studies that derive clinical prediction rules. An analysis of three pre-existing sets of large cohort data (n = 4,062-8,674) was performed. In each data set, repeated random sampling of various sample sizes, from n = 100 up to n = 2,000, was performed 100 times at each sample size and the variability in estimates of sensitivity, specificity, positive and negative likelihood ratios, posttest probabilities, odds ratios, and risk/prevalence ratios for each sample size was calculated. There were very wide, and statistically significant, differences in estimates derived from contingency tables from the same data set when calculated in sample sizes below 400 people, and typically, this variability stabilized in samples of 400-600 people. Although estimates of prevalence also varied significantly in samples below 600 people, that relationship only explains a small component of the variability in these statistical parameters. To reduce sample-specific variability, contingency tables should consist of 400 participants or more when used to derive clinical prediction rules or test their performance. Copyright © 2016 Elsevier Inc. All rights reserved.

Profiles of drug addicts in relation to personality variables and disorders.

PubMed

Carou, María; Romero, Estrella; Luengo, Mª Ángeles

2016-10-07

In recent decades, research has identified a set of impulsive/disinhibited personality variables closely associated with drug addiction. As well as this, disorders linked with these variables, such as ADHD and personality disorders, are being closely studied in the field of drug addiction. Although much knowledge has been accumulated about the relation of these variables and disorders taken separately, less is known about how these constructs allow identify-specific profiles within the drug dependent population to be identified. This work, on the basis of data collected on a sample of drug addicts in treatment, analyzes how impulsiveness, sensation seeking, self-control, ADHD and personality disorders contribute to identifying specific profiles of addicts. Cluster analysis allowed two profiles to be outlined according to these personality and psychopathology characteristics. Self-control, impulsiveness, impulsive and antisocial personality disorders, as well as scores in ADHD, emerge as the variables that contribute more to profile differentiation. One of these profiles (56.1% of participants) with a high disinhibition pattern, is associated with severe indicators of consumption and criminal career patterns. These results allow us to emphasize the role of personality and impulsiveness-related disorders in the identification of distinctive profiles within the addict population, and suggest the need to generate treatment strategies adapted to personal/psychopathology configurations of drug addicts.

Alcohol use variability in a community-based sample of nonstudent emerging adult heavy drinkers

PubMed Central

Lau-Barraco, Cathy; Braitman, Abby L.; Stamates, Amy L.; Linden-Carmichael, Ashley N.

2017-01-01

Background While nonstudent emerging adults are at elevated risk for experiencing alcohol-related problems, there remains a paucity of research devoted specifically to addressing drinking in this group. Objectives The present study sought to offer unique insights into nonstudent drinking by examining drinking variability across 30 days using a retrospective diary method. Specific aims were to: (1) compare within- and between-person variability in alcohol use across 30 days, and (2) determine the extent to which central social-cognitive between-person factors (i.e., social expectancies, perceived drinking norms, social drinking motivations) predict between-person alcohol use as well as within-person variability in drinking. Methods Participants were 195 (65.1% men) nonstudent emerging adults recruited from the community with a mean age of 21.88 (SD = 2.08) years. Results Findings showed that a substantial portion of variation in daily alcohol consumption was attributable to the within-person (83%) rather than between-person (17.2%) level. Social expectancies, perceived drinking norms, and social motives were found to influence variability in daily alcohol consumption. Conclusion Our findings contribute to knowledge that could guide efforts to design and tailor intervention strategies to minimize the harms experienced by an understudied and at-risk population of drinkers. PMID:27314308

Explaining the heterogeneous scrapie surveillance figures across Europe: a meta-regression approach.

PubMed

Del Rio Vilas, Victor J; Hopp, Petter; Nunes, Telmo; Ru, Giuseppe; Sivam, Kumar; Ortiz-Pelaez, Angel

2007-06-28

Two annual surveys, the abattoir and the fallen stock, monitor the presence of scrapie across Europe. A simple comparison between the prevalence estimates in different countries reveals that, in 2003, the abattoir survey appears to detect more scrapie in some countries. This is contrary to evidence suggesting the greater ability of the fallen stock survey to detect the disease. We applied meta-analysis techniques to study this apparent heterogeneity in the behaviour of the surveys across Europe. Furthermore, we conducted a meta-regression analysis to assess the effect of country-specific characteristics on the variability. We have chosen the odds ratios between the two surveys to inform the underlying relationship between them and to allow comparisons between the countries under the meta-regression framework. Baseline risks, those of the slaughtered populations across Europe, and country-specific covariates, available from the European Commission Report, were inputted in the model to explain the heterogeneity. Our results show the presence of significant heterogeneity in the odds ratios between countries and no reduction in the variability after adjustment for the different risks in the baseline populations. Three countries contributed the most to the overall heterogeneity: Germany, Ireland and The Netherlands. The inclusion of country-specific covariates did not, in general, reduce the variability except for one variable: the proportion of the total adult sheep population sampled as fallen stock by each country. A large residual heterogeneity remained in the model indicating the presence of substantial effect variability between countries. The meta-analysis approach was useful to assess the level of heterogeneity in the implementation of the surveys and to explore the reasons for the variation between countries.

Drugs meeting the molecular basis of diabetic kidney disease: bridging from molecular mechanism to personalized medicine.

PubMed

Lambers Heerspink, Hiddo J; Oberbauer, Rainer; Perco, Paul; Heinzel, Andreas; Heinze, Georg; Mayer, Gert; Mayer, Bernd

2015-08-01

Diabetic kidney disease (DKD) is a complex, multifactorial disease and is associated with a high risk of renal and cardiovascular morbidity and mortality. Clinical practice guidelines for diabetes recommend essentially identical treatments for all patients without taking into account how the individual responds to the instituted therapy. Yet, individuals vary widely in how they respond to medications and therefore optimal therapy differs between individuals. Understanding the underlying molecular mechanisms of variability in drug response will help tailor optimal therapy. Polymorphisms in genes related to drug pharmacokinetics have been used to explore mechanisms of response variability in DKD, but with limited success. The complex interaction between genetic make-up and environmental factors on the abundance of proteins and metabolites renders pharmacogenomics alone insufficient to fully capture response variability. A complementary approach is to attribute drug response variability to individual variability in underlying molecular mechanisms involved in the progression of disease. The interplay of different processes (e.g. inflammation, fibrosis, angiogenesis, oxidative stress) appears to drive disease progression, but the individual contribution of each process varies. Drugs at the other hand address specific targets and thereby interfere in certain disease-associated processes. At this level, biomarkers may help to gain insight into which specific pathophysiological processes are involved in an individual followed by a rational assessment whether a specific drug's mode of action indeed targets the relevant process at hand. This article describes the conceptual background and data-driven workflow developed by the SysKid consortium aimed at improving characterization of the molecular mechanisms underlying DKD at the interference of the molecular impact of individual drugs in order to tailor optimal therapy to individual patients. © The Author 2015. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

A study of lateral fall-off (penumbra) optimisation for pencil beam scanning (PBS) proton therapy

NASA Astrophysics Data System (ADS)

Winterhalter, C.; Lomax, A.; Oxley, D.; Weber, D. C.; Safai, S.

2018-01-01

The lateral fall-off is crucial for sparing organs at risk in proton therapy. It is therefore of high importance to minimize the penumbra for pencil beam scanning (PBS). Three optimisation approaches are investigated: edge-collimated uniformly weighted spots (collimation), pencil beam optimisation of uncollimated pencil beams (edge-enhancement) and the optimisation of edge collimated pencil beams (collimated edge-enhancement). To deliver energies below 70 MeV, these strategies are evaluated in combination with the following pre-absorber methods: field specific fixed thickness pre-absorption (fixed), range specific, fixed thickness pre-absorption (automatic) and range specific, variable thickness pre-absorption (variable). All techniques are evaluated by Monte Carlo simulated square fields in a water tank. For a typical air gap of 10 cm, without pre-absorber collimation reduces the penumbra only for water equivalent ranges between 4-11 cm by up to 2.2 mm. The sharpest lateral fall-off is achieved through collimated edge-enhancement, which lowers the penumbra down to 2.8 mm. When using a pre-absorber, the sharpest fall-offs are obtained when combining collimated edge-enhancement with a variable pre-absorber. For edge-enhancement and large air gaps, it is crucial to minimize the amount of material in the beam. For small air gaps however, the superior phase space of higher energetic beams can be employed when more material is used. In conclusion, collimated edge-enhancement combined with the variable pre-absorber is the recommended setting to minimize the lateral penumbra for PBS. Without collimator, it would be favourable to use a variable pre-absorber for large air gaps and an automatic pre-absorber for small air gaps.

Home oximetry to screen for obstructive sleep apnoea in Down syndrome.

PubMed

Hill, Catherine M; Elphick, Heather E; Farquhar, Michael; Gringras, Paul; Pickering, Ruth M; Kingshott, Ruth N; Martin, Jane; Reynolds, Janine; Joyce, Anna; Gavlak, Johanna C; Evans, Hazel J

2018-05-14

Children with Down syndrome are at high risk of obstructive sleep apnoea (OSA) and screening is recommended. Diagnosis of OSA should be confirmed with multichannel sleep studies. We aimed to determine whether home pulse oximetry (HPO) discriminates children at high risk of OSA, who need further diagnostic multichannel sleep studies. Cross-sectional prospective study in a training sample recruited through three UK centres. Validation sample used single-centre retrospective analysis of clinical data. Children with Down syndrome aged 0.5-6 years. Diagnostic multichannel sleep study and HPO. Sensitivity and specificity of HPO to predict moderate-to-severe OSA. 161/202 children with Down syndrome met quality criteria for inclusion and 25 had OSA. In this training sample, the best HPO parameter predictors of OSA were the delta 12 s index >0.555 (sensitivity 92%, specificity 65%) and 3% oxyhaemoglobin (SpO 2 ) desaturation index (3% ODI)>6.15 dips/hour (sensitivity 92%, specificity 63%). Combining variables (delta 12 s index, 3% ODI, mean and minimum SpO 2 ) achieved sensitivity of 96% but reduced specificity to 52%. All predictors retained or improved sensitivity in a clinical validation sample of 50 children with variable loss of specificity, best overall was the delta 12 s index, a measure of baseline SpO 2 variability (sensitivity 92%; specificity 63%). HPO screening could halve the number of children with Down syndrome needing multichannel sleep studies and reduce the burden on children, families and health services alike. This approach offers a practical universal screening approach for OSA in Down syndrome that is accessible to the non-specialist paediatrician. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Biomotor structures in elite female handball players according to performance.

PubMed

Cavala, Marijana; Rogulj, Nenad; Srhoj, Vatromir; Srhoj, Ljerka; Katić, Ratko

2008-03-01

In order to identify biomotor structures in elite female handball players, factor structures of morphological characteristics and basic motor abilities, and of variables evaluating situation motor abilities of elite female handball players (n = 53) were determined first, followed by determination of differences and relations of the morphological, motor and specific motor space according to handball performance. Factor analysis of 16 morphological measures produced three morphological factors, i.e. factor of absolute voluminosity, i.e. mesoendomorphy, factor of longitudinal skeleton dimensionality, and factor of transverse hand dimensionality. Factor analysis of 15 motor variables yielded five basic motor dimensions, i.e. factor of agility, factor of throwing explosive strength, factor of running explosive strength (sprint), factor of jumping explosive strength and factor of movement frequency rate. Factor analysis of 5 situation motor variables produced two dimensions: factor of specific agility with explosiveness and factor of specific precision with ball manipulation. Analysis of variance yielded greatest differences relative to handball performance in the factor of specific agility and throwing strength, and the factor of basic motoricity that integrates the ability of coordination (agility) with upper extremity throwing explosiveness and lower extremity sprint (30-m sprint) and jumping (standing triple jump). Considering morphological factors, the factor of voluminosity, i.e. mesoendomorphy, which is defined by muscle mass rather than adipose tissue, was found to contribute significantly to the players'performance. Results of regression analysis indicated the handball performance to be predominantly determined by the general specific motor factor based on specific agility and explosiveness, and by the morphological factor based on body mass and volume, i.e. muscle mass. Concerning basic motor abilities, the factor of movement frequency rate, which is associated with the ability of ball manipulation, was observed to predict significantly the handball players' performance.

Biodiversity of mannose-specific adhesion in Lactobacillus plantarum revisited: strain-specific domain composition of the mannose-adhesin.

PubMed

Gross, G; Snel, J; Boekhorst, J; Smits, M A; Kleerebezem, M

2010-03-01

Recently, we have identified the mannose-specific adhesin encoding gene (msa) of Lactobacillus plantarum. In the current study, structure and function of this potentially probiotic effector gene were further investigated, exploring genetic diversity of msa in L. plantarum in relation to mannose adhesion capacity. The results demonstrate that there is considerable variation in quantitative in vitro mannose adhesion capacity, which is paralleled by msa gene sequence variation. The msa genes of different L. plantarum strains encode proteins with variable domain composition. Construction of L. plantarum 299v mutant strains revealed that the msa gene product is the key-protein for mannose adhesion, also in a strain with high mannose adhering capacity. However, no straightforward correlation between adhesion capacity and domain composition of Msa in L. plantarum could be identified. Nevertheless, differences in Msa sequences in combination with variable genetic background of specific bacterial strains appears to determine mannose adhesion capacity and potentially affects probiotic properties. These findings exemplify the strain-specificity of probiotic characteristics and illustrate the need for careful and molecular selection of new candidate probiotics.

Hispanic-White Differences in Lifespan Variability in the United States

PubMed Central

Lariscy, Joseph T.; Nau, Claudia; Firebaugh, Glenn; Hummer, Robert A.

2016-01-01

This study is the first to investigate whether and, if so, why Hispanics and non-Hispanic whites in the United States differ in the variability of their lifespans. Although Hispanics enjoy higher life expectancy than whites, very little is known about how lifespan variability—and thus uncertainty about length of life—differs by race/ethnicity. We use 2010 U.S. National Vital Statistics System data to calculate lifespan variance at ages 10 and older for Hispanics and whites, and then decompose the Hispanic-white variance difference into cause-specific spread, allocation, and timing effects. In addition to their higher life expectancy relative to whites, Hispanics also exhibit 7 % lower lifespan variability, with a larger gap among women than men. Differences in cause-specific incidence (allocation effects) explain nearly two-thirds of Hispanics’ lower lifespan variability, mainly because of the higher mortality from suicide, accidental poisoning, and lung cancer among whites. Most of the remaining Hispanic-white variance difference is due to greater age dispersion (spread effects) in mortality from heart disease and residual causes among whites than Hispanics. Thus, the Hispanic paradox—that a socioeconomically disadvantaged population (Hispanics) enjoys a mortality advantage over a socioeconomically advantaged population (whites)—pertains to lifespan variability as well as to life expectancy. Efforts to reduce U.S. lifespan variability and simultaneously increase life expectancy, especially for whites, should target premature, young adult causes of death—in particular, suicide, accidental poisoning, and homicide. We conclude by discussing how the analysis of Hispanic-white differences in lifespan variability contributes to our understanding of the Hispanic paradox. PMID:26682740

A mouse model of high trait anxiety shows reduced heart rate variability that can be reversed by anxiolytic drug treatment.

PubMed

Gaburro, Stefano; Stiedl, Oliver; Giusti, Pietro; Sartori, Simone B; Landgraf, Rainer; Singewald, Nicolas

2011-11-01

Increasing evidence suggests that specific physiological measures may serve as biomarkers for successful treatment to alleviate symptoms of pathological anxiety. Studies of autonomic function investigating parameters such as heart rate (HR), HR variability and blood pressure (BP) indicated that HR variability is consistently reduced in anxious patients, whereas HR and BP data show inconsistent results. Therefore, HR and HR variability were measured under various emotionally challenging conditions in a mouse model of high innate anxiety (high anxiety behaviour; HAB) vs. control normal anxiety-like behaviour (NAB) mice. Baseline HR, HR variability and activity did not differ between mouse lines. However, after cued Pavlovian fear conditioning, both elevated tachycardia and increased fear responses were observed in HAB mice compared to NAB mice upon re-exposure to the conditioning stimulus serving as the emotional stressor. When retention of conditioned fear was tested in the home cage, HAB mice again displayed higher fear responses than NAB mice, while the HR responses were similar. Conversely, in both experimental settings HAB mice consistently exhibited reduced HR variability. Repeated administration of the anxiolytic NK1 receptor antagonist L-822429 lowered the conditioned fear response and shifted HR dynamics in HAB mice to a more regular pattern, similar to that in NAB mice. Additional receiver-operating characteristic (ROC) analysis demonstrated the high specificity and sensitivity of HR variability to distinguish between normal and high anxiety trait. These findings indicate that assessment of autonomic response in addition to freezing might be a useful indicator of the efficacy of novel anxiolytic treatments.

A comprehensive analysis of coherent rainfall patterns in China and potential drivers. Part I: Interannual variability

NASA Astrophysics Data System (ADS)

Stephan, Claudia Christine; Klingaman, Nicholas Pappas; Vidale, Pier Luigi; Turner, Andrew George; Demory, Marie-Estelle; Guo, Liang

2018-06-01

Interannual rainfall variability in China affects agriculture, infrastructure and water resource management. To improve its understanding and prediction, many studies have associated precipitation variability with particular causes for specific seasons and regions. Here, a consistent and objective method, Empirical Orthogonal Teleconnection (EOT) analysis, is applied to 1951-2007 high-resolution precipitation observations over China in all seasons. Instead of maximizing the explained space-time variance, the method identifies regions in China that best explain the temporal variability in domain-averaged rainfall. The EOT method is validated by the reproduction of known relationships to the El Niño Southern Oscillation (ENSO): high positive correlations with ENSO are found in eastern China in winter, along the Yangtze River in summer, and in southeast China during spring. New findings include that wintertime rainfall variability along the southeast coast is associated with anomalous convection over the tropical eastern Atlantic and communicated to China through a zonal wavenumber-three Rossby wave. Furthermore, spring rainfall variability in the Yangtze valley is related to upper-tropospheric midlatitude perturbations that are part of a Rossby wave pattern with its origin in the North Atlantic. A circumglobal wave pattern in the northern hemisphere is also associated with autumn precipitation variability in eastern areas. The analysis is objective, comprehensive, and produces timeseries that are tied to specific locations in China. This facilitates the interpretation of associated dynamical processes, is useful for understanding the regional hydrological cycle, and allows the results to serve as a benchmark for assessing general circulation models.

Reliable change of the sensory organization test.

PubMed

Broglio, Steven P; Ferrara, Michael S; Sopiarz, Kay; Kelly, Michael S

2008-03-01

To establish the sensitivity and specificity of the NeuroCom Sensory Organization Test (SOT) and provide practitioners with cut-scores for clinical decision making using estimates of reliable change. Retrospective cohort study. Research laboratory. Healthy (n = 66) and concussed (n = 63) young adult participants. Postural control assessments on the NeuroCom SOT were completed twice (baseline and follow-up) for both groups. Postconcussion assessments were administered within 24 hours of injury diagnosis. The reliable change technique was used to calculated cut-scores for each SOT variable (composite balance; somatosensory, visual, and vestibular ratios) at the 95%, 90%, 85%, 80%, 75%, and 70% confidence interval levels. When cut-scores were applied to the post-concussion evaluations, sensitivity and specificity varied with SOT variable and confidence interval. An evaluation for change on one or more SOT variable resulted in the highest combined sensitivity (57%) and specificity (80%) at the 75% confidence interval. Use of reliable change scores to detect significant changes in performance on the SOT resulted in decreased sensitivity and improved specificity compared to a previous report. These findings indicate that some concussed athletes may not show large changes in postconcussion postural control and this postural control evaluation should not be used in exclusion of other assessment techniques. The postural control assessment should be combined with other evaluative measures to gain the highest sensitivity to concussive injuries.

Self-reported personality variability across the social network is associated with interpersonal dysfunction.

PubMed

Clifton, Allan; Kuper, Laura E

2011-04-01

We describe 2 studies (n=52 and n=82) examining variability in perceptions of personality using a social network methodology. Undergraduate participants completed self-report measures of personality and interpersonal dysfunction and then subsequently reported on their personalities with each of 30 members of their social networks. Results across the 2 studies found substantial variability in participants' perceived personalities within their social networks. Measures of interpersonal dysfunction were associated with the amount of variability in dyadic ratings of personality, specifically Agreeableness and Openness to Experience. Results suggest that personality variability across interpersonal contexts may be an important individual difference related to social behavior and dysfunction. © 2011 The Authors. Journal of Personality © 2011, Wiley Periodicals, Inc.

Altitude Performance Characteristics of Turbojet-engine Tail-pipe Burner with Variable-area Exhaust Nozzle Using Several Fuel Systems and Flame Holders

NASA Technical Reports Server (NTRS)

Johnson, Lavern A; Meyer, Carl L

1950-01-01

A tail-pipe burner with a variable-area exhaust nozzle was investigated. From five configurations a fuel-distribution system and a flame holder were selected. The best configuration was investigated over a range of altitudes and flight Mach numbers. For the best configuration, an increase in altitude lowered the augmented thrust ratio, exhaust-gas total temperature, and tail-pipe combustion efficiency, and raised the specific fuel consumption. An increase in flight Mach number raised the augmented thrust ratio but had no apparent effect on exhaust-gas total temperature, tail-pipe combustion efficiency, or specific fuel consumption.

The slug parasitic nematode Phasmarhabditis hermaphrodita associates with complex and variable bacterial assemblages that do not affect its virulence.

PubMed

Rae, Robbie G; Tourna, Maria; Wilson, Michael J

2010-07-01

Phasmarhabditis hermaphrodita is a nematode parasite of slugs that is commercially reared in monoxenic culture with the bacterium Moraxella osloensis and sold as a biological molluscicide. However, its bacterial associations when reared in vivo in slugs are unknown. We show that when reared in vivo in slugs, P. hermaphrodita does not retain M. osloensis and associates with complex and variable bacterial assemblages that do not influence its virulence. This is in marked contrast to the entomopathogenic nematodes that form highly specific mutualistic associations with Enterobacteriaceae that are specifically retained during in vivo growth. (c) 2010 Elsevier Inc. All rights reserved.

Instrumental variable specifications and assumptions for longitudinal analysis of mental health cost offsets.

PubMed

O'Malley, A James

2012-12-01

Instrumental variables (IVs) enable causal estimates in observational studies to be obtained in the presence of unmeasured confounders. In practice, a diverse range of models and IV specifications can be brought to bear on a problem, particularly with longitudinal data where treatment effects can be estimated for various functions of current and past treatment. However, in practice the empirical consequences of different assumptions are seldom examined, despite the fact that IV analyses make strong assumptions that cannot be conclusively tested by the data. In this paper, we consider several longitudinal models and specifications of IVs. Methods are applied to data from a 7-year study of mental health costs of atypical and conventional antipsychotics whose purpose was to evaluate whether the newer and more expensive atypical antipsychotic medications lead to a reduction in overall mental health costs.

Variability analysis of SAR from 20 MHz to 2.4 GHz for different adult and child models using finite-difference time-domain

NASA Astrophysics Data System (ADS)

Conil, E.; Hadjem, A.; Lacroux, F.; Wong, M. F.; Wiart, J.

2008-03-01

This paper deals with the variability of body models used in numerical dosimetry studies. Six adult anthropomorphic voxel models have been collected and used to build 5-, 8- and 12-year-old children using a morphing method respecting anatomical parameters. Finite-difference time-domain calculations of a specific absorption rate (SAR) have been performed for a range of frequencies from 20 MHz to 2.4 GHz for isolated models illuminated by plane waves. A whole-body-averaged SAR is presented as well as the average on specific tissues such as skin, muscles, fat or bones and the average on specific parts of the body such as head, legs, arms or torso. Results point out the variability of adult models. The standard deviation of whole-body-averaged SAR of adult models can reach 40%. All phantoms are exposed to the ICNIRP reference levels. Results show that for adults, compliance with reference levels ensures compliance with basic restrictions, but concerning children models involved in this study, the whole-body-averaged SAR goes over the fundamental safety limits up to 40%. For more information on this article, see medicalphysicsweb.org

Relationship beliefs and illness appraisals are differentially associated with specific ways of coping in spouses of patients with type 2 diabetes.

PubMed

Johnson, Matthew D; Anderson, Jared R; Wilcox, Allison; Walker, Ann; Robbins, David C; Lewis, Virginia L

2013-01-01

Using data from 117 spouses of patients diagnosed with type 2 diabetes and multiple-group path analysis, the current study explored the association of four relationship beliefs (satisfaction, sacrifice, confidence and instability) and four diabetes appraisals (consequences, distress, control and efficacy) with illness-specific coping behaviour: active engagement, protective buffering and overprotection. The potential moderating effect of gender was also tested. Results indicated gender did moderate the associations among the variables in the model, with the association of relationship satisfaction and active engagement being significantly stronger for men, while diabetes control was more strongly related to protective buffering for women. The only variables associated with active engagement were three relationship-specific cognitions: higher levels of relationship satisfaction (for men only), satisfaction with sacrifice and relationship confidence were all related to higher active engagement. The diabetes appraisals were the only variables associated with protective buffering and overprotection. Higher diabetes distress and diabetes control (for women only) and lower diabetes efficacy were predictive of greater protective buffering. Lower diabetes efficacy and higher diabetes control were associated with greater overprotection. Implications for theory, research and practice are discussed.

Chemometrics Methods for Specificity, Authenticity and Traceability Analysis of Olive Oils: Principles, Classifications and Applications.

PubMed

Messai, Habib; Farman, Muhammad; Sarraj-Laabidi, Abir; Hammami-Semmar, Asma; Semmar, Nabil

2016-11-17

Olive oils (OOs) show high chemical variability due to several factors of genetic, environmental and anthropic types. Genetic and environmental factors are responsible for natural compositions and polymorphic diversification resulting in different varietal patterns and phenotypes. Anthropic factors, however, are at the origin of different blends' preparation leading to normative, labelled or adulterated commercial products. Control of complex OO samples requires their (i) characterization by specific markers; (ii) authentication by fingerprint patterns; and (iii) monitoring by traceability analysis. These quality control and management aims require the use of several multivariate statistical tools: specificity highlighting requires ordination methods; authentication checking calls for classification and pattern recognition methods; traceability analysis implies the use of network-based approaches able to separate or extract mixed information and memorized signals from complex matrices. This chapter presents a review of different chemometrics methods applied for the control of OO variability from metabolic and physical-chemical measured characteristics. The different chemometrics methods are illustrated by different study cases on monovarietal and blended OO originated from different countries. Chemometrics tools offer multiple ways for quantitative evaluations and qualitative control of complex chemical variability of OO in relation to several intrinsic and extrinsic factors.

Sensitivity and specificity of radiographic methods for predicting insertion torque of dental implants.

PubMed

Cortes, Arthur Rodriguez Gonzalez; Eimar, Hazem; Barbosa, Jorge de Sá; Costa, Claudio; Arita, Emiko Saito; Tamimi, Faleh

2015-05-01

Subjective radiographic classifications of alveolar bone have been proposed and correlated with implant insertion torque (IT). The present diagnostic study aims to identify quantitative bone features influencing IT and to use these findings to develop an objective radiographic classification for predicting IT. Demographics, panoramic radiographs (taken at the beginning of dental treatment), and cone-beam computed tomographic scans (taken for implant surgical planning) of 25 patients receiving 31 implants were analyzed. Bone samples retrieved from implant sites were assessed with dual x-ray absorptiometry, microcomputed tomography, and histology. Odds ratio, sensitivity, and specificity of all variables to predict high peak IT were assessed. A ridge cortical thickness >0.75 mm and a normal appearance of the inferior mandibular cortex were the most sensitive variables for predicting high peak IT (87.5% and 75%, respectively). A classification based on the combination of both variables presented high sensitivity (90.9%) and specificity (100%) for predicting IT. Within the limitations of this study, the results suggest that it is possible to predict IT accurately based on radiographic findings of the patient. This could be useful in the treatment plan of immediate loading cases.

Evaluation of potential water conservation using site-specific irrigation

USDA-ARS?s Scientific Manuscript database

With the advent of site-specific variable-rate irrigation (VRI) systems, irrigation can be spatially managed within sub-field-sized zones. Spatial irrigation management can optimize spatial water use efficiency and may conserve water. Spatial VRI systems are currently being managed by consultants ...

The generality of working memory capacity: a latent-variable approach to verbal and visuospatial memory span and reasoning.

PubMed

Kane, Michael J; Hambrick, David Z; Tuholski, Stephen W; Wilhelm, Oliver; Payne, Tabitha W; Engle, Randall W

2004-06-01

A latent-variable study examined whether verbal and visuospatial working memory (WM) capacity measures reflect a primarily domain-general construct by testing 236 participants in 3 span tests each of verbal WM. visuospatial WM, verbal short-term memory (STM), and visuospatial STM. as well as in tests of verbal and spatial reasoning and general fluid intelligence (Gf). Confirmatory' factor analyses and structural equation models indicated that the WM tasks largely reflected a domain-general factor, whereas STM tasks, based on the same stimuli as the WM tasks, were much more domain specific. The WM construct was a strong predictor of Gf and a weaker predictor of domain-specific reasoning, and the reverse was true for the STM construct. The findings support a domain-general view of WM capacity, in which executive-attention processes drive the broad predictive utility of WM span measures, and domain-specific storage and rehearsal processes relate more strongly to domain-specific aspects of complex cognition. ((c) 2004 APA, all rights reserved)

Fear and disgust in women: Differentiation of cardiovascular regulation patterns.

PubMed

Comtesse, Hannah; Stemmler, Gerhard

2017-02-01

Both fear and disgust facilitate avoidance of threat. From a functional view, however, cardiovascular responses to fear and disgust should differ as they prepare for appropriate behavior to protect from injury and infection, respectively. Therefore, we examined the cardiovascular responses to fear and contamination-related disgust in comparison to an emotionally neutral state induced with auditory scripts and film clips in female participants. Ten emotion and motivation self-reports and ninecardiovascular response factors derived from 23 cardiovascular variables served as dependent variables. Self-reports confirmed the specific induction of fear and disgust. In addition, fear and disgust differed in their cardiovascular response patterning. For fear, we observed specific increases in factors indicating vasoconstriction and cardiac pump function. For disgust, we found specific increases in vagal cardiac control and decreases in myocardial contractility. These findings provide support for the cardiovascular specificity of fear and disgust and are discussed in terms of a basic emotions approach. Copyright © 2016. Published by Elsevier B.V.

Reliability of a Qualitative Video Analysis for Running.

PubMed

Pipkin, Andrew; Kotecki, Kristy; Hetzel, Scott; Heiderscheit, Bryan

2016-07-01

Study Design Reliability study. Background Video analysis of running gait is frequently performed in orthopaedic and sports medicine practices to assess biomechanical factors that may contribute to injury. However, the reliability of a whole-body assessment has not been determined. Objective To determine the intrarater and interrater reliability of the qualitative assessment of specific running kinematics from a 2-dimensional video. Methods Running-gait analysis was performed on videos recorded from 15 individuals (8 male, 7 female) running at a self-selected pace (3.17 ± 0.40 m/s, 8:28 ± 1:04 min/mi) using a high-speed camera (120 frames per second). These videos were independently rated on 2 occasions by 3 experienced physical therapists using a standardized qualitative assessment. Fifteen sagittal and frontal plane kinematic variables were rated on a 3- or 5-point categorical scale at specific events of the gait cycle, including initial contact (n = 3) and midstance (n = 9), or across the full gait cycle (n = 3). The video frame number corresponding to each gait event was also recorded. Intrarater and interrater reliability values were calculated for gait-event detection (intraclass correlation coefficient [ICC] and standard error of measurement [SEM]) and the individual kinematic variables (weighted kappa [κw]). Results Gait-event detection was highly reproducible within raters (ICC = 0.94-1.00; SEM, 0.3-1.0 frames) and between raters (ICC = 0.77-1.00; SEM, 0.4-1.9 frames). Eleven of the 15 kinematic variables demonstrated substantial (κw = 0.60-0.799) or excellent (κw>0.80) intrarater agreement, with the exception of foot-to-center-of-mass position (κw = 0.59), forefoot position (κw = 0.58), ankle dorsiflexion at midstance (κw = 0.49), and center-of-mass vertical excursion (κw = 0.36). Interrater agreement for the kinematic measures varied more widely (κw = 0.00-0.85), with 5 variables showing substantial or excellent reliability. Conclusion The qualitative assessment of specific kinematic measures during running can be reliably performed with the use of a high-speed video camera. Detection of specific gait events was highly reproducible, as were common kinematic variables such as rearfoot position, foot-strike pattern, tibial inclination angle, knee flexion angle, and forward trunk lean. Other variables should be used with caution. J Orthop Sports Phys Ther 2016;46(7):556-561. Epub 6 Jun 2016. doi:10.2519/jospt.2016.6280.

Identifying populations sensitive to environmental chemicals by simulating toxicokinetic variability.

PubMed

Ring, Caroline L; Pearce, Robert G; Setzer, R Woodrow; Wetmore, Barbara A; Wambaugh, John F

2017-09-01

The thousands of chemicals present in the environment (USGAO, 2013) must be triaged to identify priority chemicals for human health risk research. Most chemicals have little of the toxicokinetic (TK) data that are necessary for relating exposures to tissue concentrations that are believed to be toxic. Ongoing efforts have collected limited, in vitro TK data for a few hundred chemicals. These data have been combined with biomonitoring data to estimate an approximate margin between potential hazard and exposure. The most "at risk" 95th percentile of adults have been identified from simulated populations that are generated either using standard "average" adult human parameters or very specific cohorts such as Northern Europeans. To better reflect the modern U.S. population, we developed a population simulation using physiologies based on distributions of demographic and anthropometric quantities from the most recent U.S. Centers for Disease Control and Prevention National Health and Nutrition Examination Survey (NHANES) data. This allowed incorporation of inter-individual variability, including variability across relevant demographic subgroups. Variability was analyzed with a Monte Carlo approach that accounted for the correlation structure in physiological parameters. To identify portions of the U.S. population that are more at risk for specific chemicals, physiologic variability was incorporated within an open-source high-throughput (HT) TK modeling framework. We prioritized 50 chemicals based on estimates of both potential hazard and exposure. Potential hazard was estimated from in vitro HT screening assays (i.e., the Tox21 and ToxCast programs). Bioactive in vitro concentrations were extrapolated to doses that produce equivalent concentrations in body tissues using a reverse dosimetry approach in which generic TK models are parameterized with: 1) chemical-specific parameters derived from in vitro measurements and predicted from chemical structure; and 2) with physiological parameters for a virtual population. For risk-based prioritization of chemicals, predicted bioactive equivalent doses were compared to demographic-specific inferences of exposure rates that were based on NHANES urinary analyte biomonitoring data. The inclusion of NHANES-derived inter-individual variability decreased predicted bioactive equivalent doses by 12% on average for the total population when compared to previous methods. However, for some combinations of chemical and demographic groups the margin was reduced by as much as three quarters. This TK modeling framework allows targeted risk prioritization of chemicals for demographic groups of interest, including potentially sensitive life stages and subpopulations. Published by Elsevier Ltd.

The Sun as a variable star: Solar and stellar irradiance variations; Colloquium of the International Astronomical Union, 143rd, Boulder, CO, Jun. 20-25, 1993

NASA Technical Reports Server (NTRS)

Pap, Judit M. (Editor); Froehlich, Claus (Editor); Hudson, Hugh S. (Editor); Tobiska, W. Kent (Editor)

1994-01-01

Variations in solar and stellar irradiances have long been of interest. An International Astronomical Union (IAU) colloquium reviewed such relevant subjects as observations, theoretical interpretations, and empirical and physical models, with a special emphasis on climatic impact of solar irradiance variability. Specific topics discussed included: (1) General Reviews on Observations of Solar and Stellar Irradiance Variability; (2) Observational Programs for Solar and Stellar Irradiance Variability; (3) Variability of Solar and Stellar Irradiance Related to the Network, Active Regions (Sunspots and Plages), and Large-Scale Magnetic Structures; (4) Empirical Models of Solar Total and Spectral Irradiance Variability; (5) Solar and Stellar Oscillations, Irradiance Variations and their Interpretations; and (6) The Response of the Earth's Atmosphere to Solar Irradiance Variations and Sun-Climate Connections.

Promoter architecture dictates cell-to-cell variability in gene expression.

PubMed

Jones, Daniel L; Brewster, Robert C; Phillips, Rob

2014-12-19

Variability in gene expression among genetically identical cells has emerged as a central preoccupation in the study of gene regulation; however, a divide exists between the predictions of molecular models of prokaryotic transcriptional regulation and genome-wide experimental studies suggesting that this variability is indifferent to the underlying regulatory architecture. We constructed a set of promoters in Escherichia coli in which promoter strength, transcription factor binding strength, and transcription factor copy numbers are systematically varied, and used messenger RNA (mRNA) fluorescence in situ hybridization to observe how these changes affected variability in gene expression. Our parameter-free models predicted the observed variability; hence, the molecular details of transcription dictate variability in mRNA expression, and transcriptional noise is specifically tunable and thus represents an evolutionarily accessible phenotypic parameter. Copyright © 2014, American Association for the Advancement of Science.

Quantifying Landscape Spatial Pattern: What Is the State of the Art?

Treesearch

Eric J. Gustafson

1998-01-01

Landscape ecology is based on the premise that there are strong links between ecological pattern and ecological function and process. Ecological systems are spatially heterogeneous, exhibiting consid-erable complexity and variability in time and space. This variability is typically represented by categorical maps or by a collection of samples taken at specific spatial...

Longitudinal Reliability of Self-Reported Age at Menarche in Adolescent Girls: Variability across Time and Setting

ERIC Educational Resources Information Center

Dorn, Lorah D.; Sontag-Padilla, Lisa M.; Pabst, Stephanie; Tissot, Abbigail; Susman, Elizabeth J.

2013-01-01

Age at menarche is critical in research and clinical settings, yet there is a dearth of studies examining its reliability in adolescents. We examined age at menarche during adolescence, specifically, (a) average method reliability across 3 years, (b) test-retest reliability between time points and methods, (c) intraindividual variability of…

Whistle-Blowing and the Code of Silence in Police Agencies: Policy and Structural Predictors

ERIC Educational Resources Information Center

Rothwell, Gary R.; Baldwin, J. Norman

2007-01-01

This article reports the findings from a study that investigates predictors of police willingness to blow the whistle and police frequency of blowing the whistle on seven forms of misconduct. It specifically investigates the capacity of nine policy and structural variables to predict whistle-blowing. The results indicate that two variables, a…

Effects of the Proximal Home Environment on Language and Behavioral Outcomes in Children Prenatally Exposed to Cocaine

ERIC Educational Resources Information Center

Bono, Katherine E.; Dinehart, Laura H. Bolzani; Dobbins, Dionne R.; Claussen, Angelika H.

2008-01-01

Proximal environmental variables illustrate aspects of the environment that are experienced directly and specifically by the child. The current study examined the associations between three proximal environmental variables: (1) quality of the home environment, (2) regularity of family routines and (3) frequency of parenting daily hassles and…

Using the Contextual Model of Learning to Understand Visitor Learning from a Science Center Exhibition

ERIC Educational Resources Information Center

Falk, John; Storksdieck, Martin

2005-01-01

Falk and Dierking's Contextual Model of Learning was used as a theoretical construct for investigating learning within a free-choice setting. A review of previous research identified key variables fundamental to free-choice science learning. The study sought to answer two questions: (1) How do specific independent variables individually contribute…

Interindividual Differences in Neonatal Imitation and the Development of Action Chains in Rhesus Macaques

ERIC Educational Resources Information Center

Ferrari, Pier Francesco; Paukner, Annika; Ruggiero, Angela; Darcey, Lisa; Unbehagen, Sarah; Suomi, Stephen J.

2009-01-01

The capacity to imitate facial gestures is highly variable in rhesus macaques and this variability may be related to differences in specific neurobehavioral patterns of development. This study evaluated the differential neonatal imitative response of 41 macaques in relation to the development of sensory, motor, and cognitive skills throughout the…

More than Numbers: Individual and Contextual Factors in How Gender Diversity Affects Women's Well-Being

ERIC Educational Resources Information Center

Miner-Rubino, Kathi; Settles, Isis H.; Stewart, Abigail J.

2009-01-01

This study examined factors related to workplace gender diversity in a sample of 87 college-educated White women. Specifically, we investigated the moderating effects of one individual difference variable (sensitivity to sexism) and one contextual variable (perceptions of the workplace climate) in the relationship between the gender composition at…

Elementary Students' Affective Variables in a Networked Learning Environment Supported by a Blog: A Case Study

ERIC Educational Resources Information Center

Allaire, Stéphane; Thériault, Pascale; Gagnon, Vincent; Lalancette, Evelyne

2013-01-01

This study documents to what extent writing on a blog in a networked learning environment could influence the affective variables of elementary-school students' writing. The framework is grounded more specifically in theory of self-determination (Deci & Ryan, 1985), relationship to writing (Chartrand & Prince, 2009) and the transactional…

Method and apparatus for conducting variable thickness vapor deposition

DOEpatents

Nesslage, G.V.

1984-08-03

A method of vapor depositing metal on a substrate in variable thickness comprises conducting the deposition continuously without interruption to avoid formation of grain boundaries. To achieve reduced deposition in specific regions a thin wire or ribbon blocking body is placed between source and substrate to partially block vapors from depositing in the region immediately below.

The Effect of Listening to Specific Musical Genre Selections on Measures of Heart Rate Variability

ERIC Educational Resources Information Center

Orman, Evelyn K.

2011-01-01

University students (N = 30) individually listened to the Billboard 100 top-ranked musical selection for their most and least liked musical genre. Two minutes of silence preceded each musical listening condition, and heart rate variability (HRV) was recorded throughout. All HRV measures decreased during music listening as compared with silence.…

Assessing West Virginia NIPF owner preferred forest management assistance topics and delivery methods

Treesearch

Daniel J. Magill; Rory F. Fraser; David W. McGill

2003-01-01

Four hundred and fourteen non-industrial private forest (NIPF) owners in West Virginia responded to a mail survey questionnaire assessing their forest management assistance topics and delivery methods of interest. Logistic regression was used to analyze 39 independent variables in relation to the dependent variables of wanting a specific topic of forestry assistance or...

Secondary Teacher Attitudes toward the Inclusion of Students with Learning Disabilities in the General Mathematics Classroom

ERIC Educational Resources Information Center

Lindsey, Jacqueline

2012-01-01

The primary focus of this study was to examine the attitudes of the secondary mathematics teachers toward the inclusion of students with learning disabilities in the general mathematics classroom. Specifically, this study was concerned with the influence of selected demographic variables and school variables on the attitudes of secondary…

Individual and hospital-specific factors influencing medical graduates' time to medical specialization.

PubMed

Johannessen, Karl-Arne; Hagen, Terje P

2013-11-01

Previous studies of gender differences in relation to medical specialization have focused more on social variables than hospital-specific factors. In a multivariate analysis with extended Cox regression, we used register data for socio-demographic variables (gender, family and having a child born during the study period) together with hospital-specific variables (the amount of supervision available, efficiency pressure and the type of teaching hospital) to study the concurrent effect of these variables on specialty qualification among all 2474 Norwegian residents who began specialization in 1999-2001. We followed the residents until 2010. A lower proportion of women qualified for a specialty in the study period (67.9% compared with 78.7% of men, p < 0.001), and they took on average six months longer than men did to complete the specialization qualification (p < 0.01). Fewer women than men entered specialties providing emergency services and those with longer working hours, and women worked shorter hours than men in all specialties. Hospital factors were significant predictors for the timely attainment of specialization: working at university hospitals (regional) or central hospitals was associated with a reduction in the time taken to complete the specialization, whereas an increased patient load and less supervision had the opposite effect. Multivariate analysis showed that the smaller proportion of women who qualified for a specialty was explained principally by childbirth and by the number of children aged under 18 years. Copyright © 2013 Elsevier Ltd. All rights reserved.

Differentiation chronic post traumatic stress disorder patients from healthy subjects using objective and subjective sleep-related parameters.

PubMed

Tahmasian, Masoud; Jamalabadi, Hamidreza; Abedini, Mina; Ghadami, Mohammad R; Sepehry, Amir A; Knight, David C; Khazaie, Habibolah

2017-05-22

Sleep disturbance is common in chronic post-traumatic stress disorder (PTSD). However, prior work has demonstrated that there are inconsistencies between subjective and objective assessments of sleep disturbance in PTSD. Therefore, we investigated whether subjective or objective sleep assessment has greater clinical utility to differentiate PTSD patients from healthy subjects. Further, we evaluated whether the combination of subjective and objective methods improves the accuracy of classification into patient versus healthy groups, which has important diagnostic implications. We recruited 32 chronic war-induced PTSD patients and 32 age- and gender-matched healthy subjects to participate in this study. Subjective (i.e. from three self-reported sleep questionnaires) and objective sleep-related data (i.e. from actigraphy scores) were collected from each participant. Subjective, objective, and combined (subjective and objective) sleep data were then analyzed using support vector machine classification. The classification accuracy, sensitivity, and specificity for subjective variables were 89.2%, 89.3%, and 89%, respectively. The classification accuracy, sensitivity, and specificity for objective variables were 65%, 62.3%, and 67.8%, respectively. The classification accuracy, sensitivity, and specificity for the aggregate variables (combination of subjective and objective variables) were 91.6%, 93.0%, and 90.3%, respectively. Our findings indicate that classification accuracy using subjective measurements is superior to objective measurements and the combination of both assessments appears to improve the classification accuracy for differentiating PTSD patients from healthy individuals. Copyright © 2017 Elsevier B.V. All rights reserved.

Anthropometrics of Italian Senior Male Rugby Union Players: From Elite to Second Division.

PubMed

Fontana, Federico Y; Colosio, Alessandro; De Roia, Gabriela F; Da Lozzo, Giorgio; Pogliaghi, Silvia

2015-09-01

Anthropometric evaluation of athletes is necessary to optimize talent identification and player development. To provide a specific anthropometric reference database of senior male rugby players competing at different levels in the southern European region. Cross-sectional. In 362 professional players (25 ± 4 y; 138 Italian national team, 97 first-division, and 127 second-division national championships) the authors measured mass, stature, and percentage body fat (plicometry). Mean, SD, and coefficient of variation were calculated for forwards and backs and for positional subgroups. Binomial logistic regression and receiver-operating-characteristic curve were performed to assess which variables best predicted level assignment (international vs national level). For all competitive levels forwards were significantly heavier and taller and had a larger percentage body fat and fat-free mass than backs. The lower the competitive level, the higher the within-role variability observed; furthermore, players in a specific positional subgroup were lighter, shorter, and fatter and had less fat-free mass. Fatfree mass is the variable that best predicts the likelihood of being classified as an international or national player (cutoff value 79.54 kg). The data confirm the specificity in the physical requirements of rugby in individual playing positions at all competitive levels and document significant differences among elite and 1st- and 2nd-division players in the same positional role. These differences may reflect the variable technical abilities, selection, training practices, and requirements of the game among these categories.

The role of context in preschool learning: a multilevel examination of the contribution of context-specific problem behaviors and classroom process quality to low-income children's approaches to learning.

PubMed

Domínguez, Ximena; Vitiello, Virginia E; Fuccillo, Janna M; Greenfield, Daryl B; Bulotsky-Shearer, Rebecca J

2011-04-01

Research suggests that promoting adaptive approaches to learning early in childhood may help close the gap between advantaged and disadvantaged children. Recent research has identified specific child-level and classroom-level variables that are significantly associated with preschoolers' approaches to learning. However, further research is needed to understand the interactive effects of these variables and determine whether classroom-level variables buffer the detrimental effects of child-level risk variables. Using a largely urban and minority sample (N=275) of preschool children, the present study examined the additive and interactive effects of children's context-specific problem behaviors and classroom process quality dimensions on children's approaches to learning. Teachers rated children's problem behavior and approaches to learning and independent assessors conducted classroom observations to assess process quality. Problem behaviors in structured learning situations and in peer and teacher interactions were found to negatively predict variance in approaches to learning. Classroom process quality domains did not independently predict variance in approaches to learning. Nonetheless, classroom process quality played an important role in these associations; high emotional support buffered the detrimental effects of problem behavior, whereas high instructional support exacerbated them. The findings of this study have important implications for classroom practices aimed at helping children who exhibit problem behaviors. Copyright © 2010 Society for the Study of School Psychology. Published by Elsevier Ltd. All rights reserved.

Panic anxiety, under the weather?

NASA Astrophysics Data System (ADS)

Bulbena, A.; Pailhez, G.; Aceña, R.; Cunillera, J.; Rius, A.; Garcia-Ribera, C.; Gutiérrez, J.; Rojo, C.

2005-03-01

The relationship between weather conditions and psychiatric disorders has been a continuous subject of speculation due to contradictory findings. This study attempts to further clarify this relationship by focussing on specific conditions such as panic attacks and non-panic anxiety in relation to specific meteorological variables. All psychiatric emergencies attended at a general hospital in Barcelona (Spain) during 2002 with anxiety as main complaint were classified as panic or non-panic anxiety according to strict independent and retrospective criteria. Both groups were assessed and compared with meteorological data (wind speed and direction, daily rainfall, temperature, humidity and solar radiation). Seasons and weekend days were also included as independent variables. Non-parametric statistics were used throughout since most variables do not follow a normal distribution. Logistic regression models were applied to predict days with and without the clinical condition. Episodes of panic were three times more common with the poniente wind (hot wind), twice less often with rainfall, and one and a half times more common in autumn than in other seasons. These three trends (hot wind, rainfall and autumn) were accumulative for panic episodes in a logistic regression formula. Significant reduction of episodes on weekends was found only for non-panic episodes. Panic attacks, unlike other anxiety episodes, in a psychiatric emergency department in Barcelona seem to show significant meteorotropism. Assessing specific disorders instead of overall emergencies or other variables of a more general quality could shed new light on the relationship between weather conditions and behaviour.

Modeling variability in air pollution-related health damages from individual airport emissions.

PubMed

Penn, Stefani L; Boone, Scott T; Harvey, Brian C; Heiger-Bernays, Wendy; Tripodis, Yorghos; Arunachalam, Sarav; Levy, Jonathan I

2017-07-01

In this study, we modeled concentrations of fine particulate matter (PM 2.5 ) and ozone (O 3 ) attributable to precursor emissions from individual airports in the United States, developing airport-specific health damage functions (deaths per 1000t of precursor emissions) and physically-interpretable regression models to explain variability in these functions. We applied the Community Multiscale Air Quality model using the Decoupled Direct Method to isolate PM 2.5 - or O 3 -related contributions from precursor pollutants emitted by 66 individual airports. We linked airport- and pollutant-specific concentrations with population data and literature-based concentration-response functions to create health damage functions. Deaths per 1000t of primary PM 2.5 emissions ranged from 3 to 160 across airports, with variability explained by population patterns within 500km of the airport. Deaths per 1000t of precursors for secondary PM 2.5 varied across airports from 0.1 to 2.7 for NOx, 0.06 to 2.9 for SO 2 , and 0.06 to 11 for VOCs, with variability explained by population patterns and ambient concentrations influencing particle formation. Deaths per 1000t of O 3 precursors ranged from -0.004 to 1.0 for NOx and 0.03 to 1.5 for VOCs, with strong seasonality and influence of ambient concentrations. Our findings reinforce the importance of location- and source-specific health damage functions in design of health-maximizing emissions control policies. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluation of Death among the Patients Undergoing Permanent Pacemaker Implantation: A Competing Risks Analysis.

PubMed

Ghaem, Haleh; Ghorbani, Mohammad; Zare Dorniani, Samira

2017-06-01

Permanent artificial pacemaker is one of the important therapies for treatment of cardiac conduction system problems. The present study aimed to determine the association between some predictive variables and all-cause and cause-specific mortality in the patients who had undergone pacemaker implantation. This study was conducted on 1207 patients who had undergone permanent pacemaker implantation in the hospitals affiliated with Shiraz University of Medical Sciences, Iran, from Mar 2002 to Mar 2012. The variables that existed in the patients' medical records included sex, diabetes mellitus, obesity, cerebrovascular accident, cardiomegaly, smoking, hypertension, ischemic heart disease, congenital heart disease, sick sinus syndrome, and atrial fibrillation. Competing risks model was used to assess the association between the predictive variables and cause-specific (i.e., cardiac and vascular) mortality. The patients' mean age was 66.32±17.92 yr (70.62±14.45 yr in the patients with single-chamber pacemakers vs. 61.91±17.69 yr in those with two-chamber pacemakers) ( P <0.001). Sick sinus syndrome and age increased the risk of all-cause mortality, while two-chamber pacemaker decreased this risk. Obesity increased the risk of cardiac death, and diabetes mellitus and heart valve disease increased the risk of vascular death. The variables predicting mortality in all-cause model were completely different from those in cause-specific model. Moreover, death in such patients may occur due to reasons other than pacemaker. Therefore, future studies, particularly prospective ones, are recommended to use competing risks models.

Tree-based flood damage modeling of companies: Damage processes and model performance

NASA Astrophysics Data System (ADS)

Sieg, Tobias; Vogel, Kristin; Merz, Bruno; Kreibich, Heidi

2017-07-01

Reliable flood risk analyses, including the estimation of damage, are an important prerequisite for efficient risk management. However, not much is known about flood damage processes affecting companies. Thus, we conduct a flood damage assessment of companies in Germany with regard to two aspects. First, we identify relevant damage-influencing variables. Second, we assess the prediction performance of the developed damage models with respect to the gain by using an increasing amount of training data and a sector-specific evaluation of the data. Random forests are trained with data from two postevent surveys after flood events occurring in the years 2002 and 2013. For a sector-specific consideration, the data set is split into four subsets corresponding to the manufacturing, commercial, financial, and service sectors. Further, separate models are derived for three different company assets: buildings, equipment, and goods and stock. Calculated variable importance values reveal different variable sets relevant for the damage estimation, indicating significant differences in the damage process for various company sectors and assets. With an increasing number of data used to build the models, prediction errors decrease. Yet the effect is rather small and seems to saturate for a data set size of several hundred observations. In contrast, the prediction improvement achieved by a sector-specific consideration is more distinct, especially for damage to equipment and goods and stock. Consequently, sector-specific data acquisition and a consideration of sector-specific company characteristics in future flood damage assessments is expected to improve the model performance more than a mere increase in data.

Inter- and intra-specific variability in δ13C and δ18O values of freshwater gastropod shells from Lake Lednica, western Poland

NASA Astrophysics Data System (ADS)

Apolinarska, Karina; Pełechaty, Mariusz

2017-09-01

This study focuses on the inter- and intra-specific variability in δ13C and δ18O values of shells and opercula of gastropods sampled live from the littoral zone of Lake Lednica, western Poland. The δ13C and δ18O values were measured in individual opercula of Bithynia tentaculata and in shells of Bithynia tentaculata, Gyraulus albus, Gyraulus crista, Lymnaea sp., Physa fontinalis, Radix auricularia, Theodoxus fluviatilis and Valvata cristata. The gastropods selected for the study are among the species most commonly found in European Quaternary lacustrine sediments. The carbon isotope composition of the gastropod shells was species-specific and the same order of species from the most to the least 13C-depleted was observed at all sites sampled. Differences in shell δ13C values between species were similar at all sampling sites, thus the factors influencing shell isotopic composition were interpreted as species-specific. The δ18O values of shells were similar in all the species investigated. Significant intra-specific variability in shell δ13C and δ18O values was observed not only within the populations of Lake Lednica, which can be explained by heterogeneity of δ13C DIC, δ18O water and water temperature between the sites where macrophytes with snails attached were sampled, but also between individuals sampled from restricted areas of the lake's bottom. The latter points to the importance of factors related to the ontogeny of individual gastropods.

[Analysis of the technical efficiency of hospitals in the Spanish National Health Service].

PubMed

Pérez-Romero, Carmen; Ortega-Díaz, M Isabel; Ocaña-Riola, Ricardo; Martín-Martín, José Jesús

To analyse the technical efficiency and productivity of general hospitals in the Spanish National Health Service (NHS) (2010-2012) and identify explanatory hospital and regional variables. 230 NHS hospitals were analysed by data envelopment analysis for overall, technical and scale efficiency, and Malmquist index. The robustness of the analysis is contrasted with alternative input-output models. A fixed effects multilevel cross-sectional linear model was used to analyse the explanatory efficiency variables. The average rate of overall technical efficiency (OTE) was 0.736 in 2012; there was considerable variability by region. Malmquist index (2010-2012) is 1.013. A 23% variability in OTE is attributable to the region in question. Statistically significant exogenous variables (residents per 100 physicians, aging index, average annual income per household, essential public service expenditure and public health expenditure per capita) explain 42% of the OTE variability between hospitals and 64% between regions. The number of residents showed a statistically significant relationship. As regards regions, there is a statistically significant direct linear association between OTE and annual income per capita and essential public service expenditure, and an indirect association with the aging index and annual public health expenditure per capita. The significant room for improvement in the efficiency of hospitals is conditioned by region-specific characteristics, specifically aging, wealth and the public expenditure policies of each one. Copyright © 2016 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

Teachers' Situation-Specific Mastery Experiences: Teacher, Student Group and Lesson Effects

ERIC Educational Resources Information Center

Malmberg, Lars-Erik; Hagger, Hazel; Webster, Sophie

2014-01-01

Following a model on the cyclical nature of teacher ("trait") self-efficacy and context-, task- and situation-specific ("state") "mastery experiences" (TSSME), we investigated the variability and effects of lesson characteristics (e.g. lesson sequence), student group characteristics (e.g. proportion of students…

Do Dispositional Characteristics Influence Reading? Examining the Impact of Personality on Reading Fluency

ERIC Educational Resources Information Center

Krach, S. Kathleen; McCreery, Michael P.; Loe, Scott A.; Jones, W. Paul

2016-01-01

Previous research demonstrates specific relationships between personality traits and general academic performance. In addition, research studies have demonstrated relationships among personality and variables related to reading fluency (i.e. speed, accuracy, automaticity, and prosody). However, little investigation has examined specific links…

Developing Clade-Specific Microsatellite Markers: A Case Study in the Filamentous Fungal Genus Aspergillus

USDA-ARS?s Scientific Manuscript database

Microsatellite markers are highly variable and very commonly used in population genetics studies. However, microsatellite loci are typically poorly conserved and cannot be used in distant related species. Thus, development of clade-specific microsatellite markers would increase efficiency and allow ...

Humidity: A review and primer on atmospheric moisture and human health.

PubMed

Davis, Robert E; McGregor, Glenn R; Enfield, Kyle B

2016-01-01

Research examining associations between weather and human health frequently includes the effects of atmospheric humidity. A large number of humidity variables have been developed for numerous purposes, but little guidance is available to health researchers regarding appropriate variable selection. We examine a suite of commonly used humidity variables and summarize both the medical and biometeorological literature on associations between humidity and human health. As an example of the importance of humidity variable selection, we correlate numerous hourly humidity variables to daily respiratory syncytial virus isolates in Singapore from 1992 to 1994. Most water-vapor mass based variables (specific humidity, absolute humidity, mixing ratio, dewpoint temperature, vapor pressure) exhibit comparable correlations. Variables that include a thermal component (relative humidity, dewpoint depression, saturation vapor pressure) exhibit strong diurnality and seasonality. Humidity variable selection must be dictated by the underlying research question. Despite being the most commonly used humidity variable, relative humidity should be used sparingly and avoided in cases when the proximity to saturation is not medically relevant. Care must be taken in averaging certain humidity variables daily or seasonally to avoid statistical biasing associated with variables that are inherently diurnal through their relationship to temperature. Copyright © 2015 Elsevier Inc. All rights reserved.

Development and internal validation of a side-specific, multiparametric magnetic resonance imaging-based nomogram for the prediction of extracapsular extension of prostate cancer.

PubMed

Martini, Alberto; Gupta, Akriti; Lewis, Sara C; Cumarasamy, Shivaram; Haines, Kenneth G; Briganti, Alberto; Montorsi, Francesco; Tewari, Ashutosh K

2018-04-19

To develop a nomogram for predicting side-specific extracapsular extension (ECE) for planning nerve-sparing radical prostatectomy. We retrospectively analysed data from 561 patients who underwent robot-assisted radical prostatectomy between February 2014 and October 2015. To develop a side-specific predictive model, we considered the prostatic lobes separately. Four variables were included: prostate-specific antigen; highest ipsilateral biopsy Gleason grade; highest ipsilateral percentage core involvement; and ECE on multiparametric magnetic resonance imaging (mpMRI). A multivariable logistic regression analysis was fitted to predict side-specific ECE. A nomogram was built based on the coefficients of the logit function. Internal validation was performed using 'leave-one-out' cross-validation. Calibration was graphically investigated. The decision curve analysis was used to evaluate the net clinical benefit. The study population consisted of 829 side-specific cases, after excluding negative biopsy observations (n = 293). ECE was reported on mpMRI and final pathology in 115 (14%) and 142 (17.1%) cases, respectively. Among these, mpMRI was able to predict ECE correctly in 57 (40.1%) cases. All variables in the model except highest percentage core involvement were predictors of ECE (all P ≤ 0.006). All variables were considered for inclusion in the nomogram. After internal validation, the area under the curve was 82.11%. The model demonstrated excellent calibration and improved clinical risk prediction, especially when compared with relying on mpMRI prediction of ECE alone. When retrospectively applying the nomogram-derived probability, using a 20% threshold for performing nerve-sparing, nine out of 14 positive surgical margins (PSMs) at the site of ECE resulted above the threshold. We developed an easy-to-use model for the prediction of side-specific ECE, and hope it serves as a tool for planning nerve-sparing radical prostatectomy and in the reduction of PSM in future series. © 2018 The Authors BJU International © 2018 BJU International Published by John Wiley & Sons Ltd.

On the specification of structural equation models for ecological systems

USGS Publications Warehouse

Grace, J.B.; Michael, Anderson T.; Han, O.; Scheiner, S.M.

2010-01-01

The use of structural equation modeling (SEM) is often motivated by its utility for investigating complex networks of relationships, but also because of its promise as a means of representing theoretical concepts using latent variables. In this paper, we discuss characteristics of ecological theory and some of the challenges for proper specification of theoretical ideas in structural equation models (SE models). In our presentation, we describe some of the requirements for classical latent variable models in which observed variables (indicators) are interpreted as the effects of underlying causes. We also describe alternative model specifications in which indicators are interpreted as having causal influences on the theoretical concepts. We suggest that this latter nonclassical specification (which involves another variable type-the composite) will often be appropriate for ecological studies because of the multifaceted nature of our theoretical concepts. In this paper, we employ the use of meta-models to aid the translation of theory into SE models and also to facilitate our ability to relate results back to our theories. We demonstrate our approach by showing how a synthetic theory of grassland biodiversity can be evaluated using SEM and data from a coastal grassland. In this example, the theory focuses on the responses of species richness to abiotic stress and disturbance, both directly and through intervening effects on community biomass. Models examined include both those based on classical forms (where each concept is represented using a single latent variable) and also ones in which the concepts are recognized to be multifaceted and modeled as such. To address the challenge of matching SE models with the conceptual level of our theory, two approaches are illustrated, compositing and aggregation. Both approaches are shown to have merits, with the former being preferable for cases where the multiple facets of a concept have widely differing effects in the system and the latter being preferable where facets act together consistently when influencing other parts of the system. Because ecological theory characteristically deals with concepts that are multifaceted, we expect the methods presented in this paper will be useful for ecologists wishing to use SEM. ?? 2010 by the Ecological Society of America.

Distributions of eight meteorological variables at Cape Kennedy, Florida and Vandenberg Air Force Base, California

NASA Technical Reports Server (NTRS)

Graves, M. E.; King, R. L.; Brown, S. C.

1973-01-01

Extreme values, median values, and nine percentile values are tabulated for eight meteorological variables at Cape Kennedy, Florida and at Vandenberg Air Force Base, California. The variables are temperature, relative humidity, station pressure, water vapor pressure, water vapor mixing ratio, density, and enthalpy. For each month eight hours are tabulated, namely, 0100, 0400, 0700, 1000, 1300, 1600, 1900, and 2200 local time. These statistics are intended for general use for the space shuttle design trade-off analysis and are not to be used for specific design values.

Secure quantum key distribution using continuous variables of single photons.

PubMed

Zhang, Lijian; Silberhorn, Christine; Walmsley, Ian A

2008-03-21

We analyze the distribution of secure keys using quantum cryptography based on the continuous variable degree of freedom of entangled photon pairs. We derive the information capacity of a scheme based on the spatial entanglement of photons from a realistic source, and show that the standard measures of security known for quadrature-based continuous variable quantum cryptography (CV-QKD) are inadequate. A specific simple eavesdropping attack is analyzed to illuminate how secret information may be distilled well beyond the bounds of the usual CV-QKD measures.

Site-specific management of cotton root rot using airborne and satellite imagery

USDA-ARS?s Scientific Manuscript database

Cotton root rot is a serious cotton disease that can now be effectively controlled with Topguard Terra Fungicide. The objectives of this research were to demonstrate how site-specific fungicide application could be implemented based on historical remote sensing imagery and variable rate technology. ...

Testing Specific Hypotheses Concerning Latent Group Differences in Multi-group Covariance Structure Analysis with Structured Means.

ERIC Educational Resources Information Center

Dolan, Conor V.; Molenaar, Peter C. M.

1994-01-01

In multigroup covariance structure analysis with structured means, the traditional latent selection model is formulated as a special case of phenotypic selection. Illustrations with real and simulated data demonstrate how one can test specific hypotheses concerning selection on latent variables. (SLD)

Perceived Relational Support in Adolescence: Dimensions, Configurations, and Adolescent Adjustment.

ERIC Educational Resources Information Center

Scholte, Ron H. J.; van Lieshout, Cornelis F. M.; van Aken, Marcel A. G.

2001-01-01

Examined characteristics of perceived relational support from four key providers for 12- to 18-year-olds. Variable-centered factor analyses yielded five support dimensions, three specific to providers and two specific to provisions. Person-centered factor analyses identified five types of adolescents with different configurations of perceived…

New Approach to Total Dose Specification for Spacecraft Electronics

NASA Technical Reports Server (NTRS)

Xapsos, Michael

2017-01-01

Variability of the space radiation environment is investigated with regard to total dose specification for spacecraft electronics. It is shown to have a significant impact. A new approach is developed for total dose requirements that replaces the radiation design margin concept with failure probability during a mission.

Effects of Verb Familiarity on Finiteness Marking in Children with Specific Language Impairment

ERIC Educational Resources Information Center

Abel, Alyson D.; Rice, Mabel L.; Bontempo, Daniel E.

2015-01-01

Purpose: Children with specific language impairment (SLI) have known deficits in the verb lexicon and finiteness marking. This study investigated a potential relationship between these 2 variables in children with SLI and 2 control groups considering predictions from 2 different theoretical perspectives, morphosyntactic versus morphophonological.…

Bayesian Estimation of Panel Data Fractional Response Models with Endogeneity: An Application to Standardized Test Rates

ERIC Educational Resources Information Center

Kessler, Lawrence M.

2013-01-01

In this paper I propose Bayesian estimation of a nonlinear panel data model with a fractional dependent variable (bounded between 0 and 1). Specifically, I estimate a panel data fractional probit model which takes into account the bounded nature of the fractional response variable. I outline estimation under the assumption of strict exogeneity as…

Tense Marking in Black English. A Linguistic and Social Analysis. Urban Language Series, No. 8.

ERIC Educational Resources Information Center

Fasold, Ralph W.

In recent years a considerable amount of interest has developed in language variability and in the educational problems connected with it. This volume is a report of linguistic research on the variable language behavior in a community of American English speakers, specifically on some aspects of tense marking in Black English. The following topics…

Fuels planning: science synthesis and integration; economic uses fact sheet 08: prescribed fire costs

Treesearch

Rocky Mountain Research Station USDA Forest Service

2004-01-01

Although the use of prescribed fire as a management tool is widespread, there is great variability and uncertainty in the treatment costs. Given specific site variables and management objectives, how much will it cost to use prescribed fire? This paper describes the FASTRACS database, a tool that has been developed to aid managers in addressing this question.

Psychological Well-Being of Mothers of Youth with Fragile X Syndrome: Syndrome Specificity and within-Syndrome Variability

ERIC Educational Resources Information Center

Lewis, P.; Abbeduto, L.; Murphy, M.; Richmond, E.; Giles, N.; Bruno, L.; Schroeder, S.; Anderson, J.; Orsmond, G.

2006-01-01

Background: Research on parental well-being has focused largely on Down syndrome and autism; however, fragile X syndrome is likely to pose different challenges for parents compared with these other diagnostic conditions. Moreover, there is considerable variability among youth with fragile X syndrome; for example, 25% to 33% of affected youth meet…

An Investigation of Selected Variables Related to Student Algebra I Performance in Mississippi

ERIC Educational Resources Information Center

Scott, Undray

2016-01-01

This research study attempted to determine if specific variables were related to student performance on the Algebra I subject-area test. This study also sought to determine in which of grades 8, 9, or 10 students performed better on the Algebra I Subject Area Test. This study also investigated the different criteria that are used to schedule…

A Study of the Relationship between Cognitive Emotion Regulation, Optimism, and Perceived Stress among Selected Teachers in Lutheran Schools

ERIC Educational Resources Information Center

Gliebe, Sudi Kate

2012-01-01

Problem: The problem of this study was to determine the relationship between perceived stress, as measured by the Perceived Stress Scale (PSS), and a specific set of predictor variables among selected teachers in Lutheran schools in the United States. These variables were cognitive emotion regulation strategies (positive reappraisal and…

A Probabilistic Model for Students' Errors and Misconceptions on the Structure of Matter in Relation to Three Cognitive Variables

ERIC Educational Resources Information Center

Tsitsipis, Georgios; Stamovlasis, Dimitrios; Papageorgiou, George

2012-01-01

In this study, the effect of 3 cognitive variables such as logical thinking, field dependence/field independence, and convergent/divergent thinking on some specific students' answers related to the particulate nature of matter was investigated by means of probabilistic models. Besides recording and tabulating the students' responses, a combination…

Not All Children Agree: Acquisition of Agreement when the Input Is Variable

ERIC Educational Resources Information Center

Miller, Karen

2012-01-01

In this paper we investigate the effect of variable input on the acquisition of grammar. More specifically, we examine the acquisition of the third person singular marker -s on the auxiliary "do" in comprehension and production in two groups of children who are exposed to similar varieties of English but that differ with respect to adult…

Using a Lag Schedule to Increase Variability of Verbal Responding in an Individual with Autism

ERIC Educational Resources Information Center

Susa, Carrie; Schlinger, Henry D., Jr.

2012-01-01

Research has shown that reinforcing novel behaviors can increase the number of different ways that an individual behaves (Goetz & Baer, 1973; Pryor, Haag, & O'Reilly, 1969). However, it was not until more recently that researchers began to consider "variability" to be a reinforceable operant in and of itself (Neuringer, 2002). More specifically,…

Emotional and Cognitive Variables Associated with Contamination-Related Obsessive-Compulsive Symptoms.

PubMed

García-Soriano, Gemma; Rosell-Clari, Vicent; Serrano, Miguel Ángel

2016-05-23

Different variables have been associated with the development/ maintenance of contamination-related obsessive-compulsive disorder (OCD), although the relevance of these factors has not been clearly established. The present study aimed to analyze the relevance and specificity of these variables. Forty-five women with high scores on obsessive-compulsive contamination symptoms (n = 16) or checking symptoms (n = 15), or non-clinical scores (n = 14) participated in a behavioral approach/avoidance task (BAT) with a contamination-OCD stimulus. Vulnerability variables and participants' emotional, cognitive, physiological and behavioral responses to the BAT were appraised. Results show that fear of illness was a relevant vulnerability variable specific to contamination participants (p = .001; η2 p = .291). Contamination participants responded with significantly higher subjective disgust (p =.001; η2 p = .269), anxiety (p = .001; η2 p = .297), urge to wash (p < .001; η2 p = 370), threat from emotion (p < .001; η2 p = .338) and contamination severity (p = .002; η2 p = .260) appraisals, and with lower behavioral approach (p = .008; η2 p = .208) than the other two groups. Moreover, contamination participants showed lower heart rate acceleration (p = .046; η2 p = .170) and higher contamination likelihood appraisals (p < .001; η2 p = .342) than the non-clinical group. Urge to wash was predicted by state disgust (R 2 change = .346) and threat from emotion (R 2 change = .088). These responses were predicted by general anxiety sensitivity (R 2 change = .161), disgust propensity (R 2 change = .255) and fear of illness (R 2 change = .116), but not by other vulnerability variables such as dysfunctional beliefs about thoughts (Responsibility and Overestimation of threat) or disgust sensitivity. State disgust, threat from disgust, anxiety sensitivity and fear of illness were found to be the most relevant variables in contamination symptoms.

Assessment of economic status in trauma registries: A new algorithm for generating population-specific clustering-based models of economic status for time-constrained low-resource settings.

PubMed

Eyler, Lauren; Hubbard, Alan; Juillard, Catherine

2016-10-01

Low and middle-income countries (LMICs) and the world's poor bear a disproportionate share of the global burden of injury. Data regarding disparities in injury are vital to inform injury prevention and trauma systems strengthening interventions targeted towards vulnerable populations, but are limited in LMICs. We aim to facilitate injury disparities research by generating a standardized methodology for assessing economic status in resource-limited country trauma registries where complex metrics such as income, expenditures, and wealth index are infeasible to assess. To address this need, we developed a cluster analysis-based algorithm for generating simple population-specific metrics of economic status using nationally representative Demographic and Health Surveys (DHS) household assets data. For a limited number of variables, g, our algorithm performs weighted k-medoids clustering of the population using all combinations of g asset variables and selects the combination of variables and number of clusters that maximize average silhouette width (ASW). In simulated datasets containing both randomly distributed variables and "true" population clusters defined by correlated categorical variables, the algorithm selected the correct variable combination and appropriate cluster numbers unless variable correlation was very weak. When used with 2011 Cameroonian DHS data, our algorithm identified twenty economic clusters with ASW 0.80, indicating well-defined population clusters. This economic model for assessing health disparities will be used in the new Cameroonian six-hospital centralized trauma registry. By describing our standardized methodology and algorithm for generating economic clustering models, we aim to facilitate measurement of health disparities in other trauma registries in resource-limited countries. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Running Technique is an Important Component of Running Economy and Performance

PubMed Central

FOLLAND, JONATHAN P.; ALLEN, SAM J.; BLACK, MATTHEW I.; HANDSAKER, JOSEPH C.; FORRESTER, STEPHANIE E.

2017-01-01

ABSTRACT Despite an intuitive relationship between technique and both running economy (RE) and performance, and the diverse techniques used by runners to achieve forward locomotion, the objective importance of overall technique and the key components therein remain to be elucidated. Purpose This study aimed to determine the relationship between individual and combined kinematic measures of technique with both RE and performance. Methods Ninety-seven endurance runners (47 females) of diverse competitive standards performed a discontinuous protocol of incremental treadmill running (4-min stages, 1-km·h−1 increments). Measurements included three-dimensional full-body kinematics, respiratory gases to determine energy cost, and velocity of lactate turn point. Five categories of kinematic measures (vertical oscillation, braking, posture, stride parameters, and lower limb angles) and locomotory energy cost (LEc) were averaged across 10–12 km·h−1 (the highest common velocity < velocity of lactate turn point). Performance was measured as season's best (SB) time converted to a sex-specific z-score. Results Numerous kinematic variables were correlated with RE and performance (LEc, 19 variables; SB time, 11 variables). Regression analysis found three variables (pelvis vertical oscillation during ground contact normalized to height, minimum knee joint angle during ground contact, and minimum horizontal pelvis velocity) explained 39% of LEc variability. In addition, four variables (minimum horizontal pelvis velocity, shank touchdown angle, duty factor, and trunk forward lean) combined to explain 31% of the variability in performance (SB time). Conclusions This study provides novel and robust evidence that technique explains a substantial proportion of the variance in RE and performance. We recommend that runners and coaches are attentive to specific aspects of stride parameters and lower limb angles in part to optimize pelvis movement, and ultimately enhance performance. PMID:28263283

Survival of white-tailed deer neonates in Minnesota and South Dakota

USGS Publications Warehouse

Grovenburg, T.W.; Swanson, C.C.; Jacques, C.N.; Klaver, R.W.; Brinkman, T.J.; Burris, B.M.; Deperno, C.S.; Jenks, J.A.

2011-01-01

Understanding the influence of intrinsic (e.g., age, birth mass, and sex) and habitat factors on survival of neonate white-tailed deer improves understanding of population ecology. During 2002–2004, we captured and radiocollared 78 neonates in eastern South Dakota and southwestern Minnesota, of which 16 died before 1 September. Predation accounted for 80% of mortality; the remaining 20% was attributed to starvation. Canids (coyotes [Canis latrans], domestic dogs) accounted for 100% of predation on neonates. We used known fate analysis in Program MARK to estimate survival rates and investigate the influence of intrinsic and habitat variables on survival. We developed 2 a priori model sets, including intrinsic variables (model set 1) and habitat variables (model set 2; forested cover, wetlands, grasslands, and croplands). For model set 1, model {Sage-interval} had the lowest AICc (Akaike's information criterion for small sample size) value, indicating that age at mortality (3-stage age-interval: 0–2 weeks, 2–8 weeks, and >8 weeks) best explained survival. Model set 2 indicated that habitat variables did not further influence survival in the study area; β-estimates and 95% confidence intervals for habitat variables in competing models encompassed zero; thus, we excluded these models from consideration. Overall survival rate using model {Sage-interval} was 0.87 (95% CI = 0.83–0.91); 61% of mortalities occurred at 0–2 weeks of age, 26% at 2–8 weeks of age, and 13% at >8 weeks of age. Our results indicate that variables influencing survival may be area specific. Region-specific data are needed to determine influences of intrinsic and habitat variables on neonate survival before wildlife managers can determine which habitat management activities influence neonate populations.

Increased Force Variability in Chronic Stroke: Contributions of Force Modulation below 1 Hz

PubMed Central

Lodha, Neha; Misra, Gaurav; Coombes, Stephen A.; Christou, Evangelos A.; Cauraugh, James H.

2013-01-01

Increased force variability constitutes a hallmark of arm disabilities following stroke. Force variability is related to the modulation of force below 1 Hz in healthy young and older adults. However, whether the increased force variability observed post stroke is related to the modulation of force below 1 Hz remains unknown. Thus, the purpose of this study was to compare force modulation below 1 Hz in chronic stroke and age-matched healthy individuals. Both stroke and control individuals (N = 26) performed an isometric grip task to submaximal force levels. Coefficient of variation quantified force variability, and power spectrum density of force quantified force modulation below 1 Hz with a high resolution (0.07 Hz). Analyses indicated that force variability was greater for the stroke group compared with to healthy controls and for the paretic hand compared with the non-paretic hand. Force modulation below 1 Hz differentiated the stroke individuals and healthy controls, as well as the paretic and non-paretic hands. Specifically, stroke individuals (paretic hand) exhibited greater power ∼0.2 Hz (0.07–0.35 Hz) and lesser power ∼0.6 Hz (0.49–0.77 Hz) compared to healthy controls (non-dominant hand). Similarly, the paretic hand exhibited greater power ∼0.2 Hz, and lesser power ∼0.6 Hz than the non-paretic hand. Moreover, variability of force was strongly predicted from the modulation of specific frequencies below 1 Hz (R 2 = 0.80). Together, these findings indicate that the modulation of force below 1 Hz provides significant insight into changes in motor control after stroke. PMID:24386208

Some anthropologic characteristics of elite female handball players at different playing positions.

PubMed

Rogulj, Nenad; Srhoj, Vatromir; Nazor, Mirjana; Srhoj, Ljerka; Cavala, Marijana

2005-12-01

Differences in motor and psychologic variables according to playing positions were analyzed in a sample of 53 elite female handball players, members of junior and senior national team. Motor status included 8 variables for assessment of explosive strength of landing and throwing, agility, speed strength, movement frequency, and flexibility. Psychologic status was analyzed through 4 dimensions according to Eysenck: extroversion, psychotic behavior, neurotic behavior, and lie. The anthropologic features analyzed showed statistically significant differences. Considering motor abilities, differences were recorded in the variables for assessment of speed strength, agility and leg movement frequency, where wings predominated, whereas goalkeepers showed predominance in flexibility. In psychologic status, differences were present in the variable for assessment of extroversion, which was most pronounced in wings, whereas psychotic behavior was more expressed in those at pivot position. The differences were primarily consequential to the selection of players of a specific anthropologic profile for particular playing positions. The hypothesis of the impact of kinesiologic specificities of a particular playing position on the formation of the players' anthropologic profile should be scientifically tested. Study results may found application in training and contest practice, especially in forming anthropologic models for particular positions during the process of player selection.

Use of real-time monitoring to predict concentrations of select constituents in the Menomonee River drainage basin, Southeast Wisconsin, 2008-9

USGS Publications Warehouse

Baldwin, Austin K.; Graczyk, David J.; Robertson, Dale M.; Saad, David A.; Magruder, Christopher

2012-01-01

The models to estimate chloride concentrations all used specific conductance as the explanatory variable, except for the model for the Little Menomonee River near Freistadt, which used both specific conductance and turbidity as explanatory variables. Adjusted R2 values for the chloride models ranged from 0.74 to 0.97. Models to estimate total suspended solids and total phosphorus used turbidity as the only explanatory variable. Adjusted R2 values ranged from 0.77 to 0.94 for the total suspended solids models and from 0.55 to 0.75 for the total phosphorus models. Models to estimate indicator bacteria used water temperature and turbidity as the explanatory variables, with adjusted R2 values from 0.54 to 0.69 for Escherichia coli bacteria models and from 0.54 to 0.74 for fecal coliform bacteria models. Dissolved oxygen was not used in any of the final models. These models may help managers measure the effects of land-use changes and improvement projects, establish total maximum daily loads, estimate important water-quality indicators such as bacteria concentrations, and enable informed decision making in the future.

Detecting subject-specific activations using fuzzy clustering

PubMed Central

Seghier, Mohamed L.; Friston, Karl J.; Price, Cathy J.

2007-01-01

Inter-subject variability in evoked brain responses is attracting attention because it may reflect important variability in structure–function relationships over subjects. This variability could be a signature of degenerate (many-to-one) structure–function mappings in normal subjects or reflect changes that are disclosed by brain damage. In this paper, we describe a non-iterative fuzzy clustering algorithm (FCP: fuzzy clustering with fixed prototypes) for characterizing inter-subject variability in between-subject or second-level analyses of fMRI data. The approach identifies the contribution of each subject to response profiles in voxels surviving a classical F-statistic criterion. The output identifies subjects who drive activation in specific cortical regions (local effects) or in voxels distributed across neural systems (global effects). The sensitivity of the approach was assessed in 38 normal subjects performing an overt naming task. FCP revealed that several subjects had either abnormally high or abnormally low responses. FCP may be particularly useful for characterizing outlier responses in rare patients or heterogeneous populations. In these cases, atypical activations may not be detected by standard tests, under parametric assumptions. The advantage of using FCP is that it searches all voxels systematically and can identify atypical activation patterns in a quantitative and unsupervised manner. PMID:17478103

Pathogen prevalence predicts human cross-cultural variability in individualism/collectivism

PubMed Central

Fincher, Corey L; Thornhill, Randy; Murray, Damian R; Schaller, Mark

2008-01-01

Pathogenic diseases impose selection pressures on the social behaviour of host populations. In humans (Homo sapiens), many psychological phenomena appear to serve an antipathogen defence function. One broad implication is the existence of cross-cultural differences in human cognition and behaviour contingent upon the relative presence of pathogens in the local ecology. We focus specifically on one fundamental cultural variable: differences in individualistic versus collectivist values. We suggest that specific behavioural manifestations of collectivism (e.g. ethnocentrism, conformity) can inhibit the transmission of pathogens; and so we hypothesize that collectivism (compared with individualism) will more often characterize cultures in regions that have historically had higher prevalence of pathogens. Drawing on epidemiological data and the findings of worldwide cross-national surveys of individualism/collectivism, our results support this hypothesis: the regional prevalence of pathogens has a strong positive correlation with cultural indicators of collectivism and a strong negative correlation with individualism. The correlations remain significant even when controlling for potential confounding variables. These results help to explain the origin of a paradigmatic cross-cultural difference, and reveal previously undocumented consequences of pathogenic diseases on the variable nature of human societies. PMID:18302996

The absence of an Atlantic imprint on the multidecadal variability of wintertime European temperature.

PubMed

Yamamoto, Ayako; Palter, Jaime B

2016-03-15

Northern Hemisphere climate responds sensitively to multidecadal variability in North Atlantic sea surface temperature (SST). It is therefore surprising that an imprint of such variability is conspicuously absent in wintertime western European temperature, despite that Europe's climate is strongly influenced by its neighbouring ocean, where multidecadal variability in basin-average SST persists in all seasons. Here we trace the cause of this missing imprint to a dynamic anomaly of the atmospheric circulation that masks its thermodynamic response to SST anomalies. Specifically, differences in the pathways Lagrangian particles take to Europe during anomalous SST winters suppress the expected fluctuations in air-sea heat exchange accumulated along those trajectories. Because decadal variability in North Atlantic-average SST may be driven partly by the Atlantic Meridional Overturning Circulation (AMOC), the atmosphere's dynamical adjustment to this mode of variability may have important implications for the European wintertime temperature response to a projected twenty-first century AMOC decline.

Discerning strain effects in microbial dose-response data.

PubMed

Coleman, Margaret E; Marks, Harry M; Golden, Neal J; Latimer, Heejeong K

In order to estimate the risk or probability of adverse events in risk assessment, it is necessary to identify the important variables that contribute to the risk and provide descriptions of distributions of these variables for well-defined populations. One component of modeling dose response that can create uncertainty is the inherent genetic variability among pathogenic bacteria. For many microbial risk assessments, the "default" assumption used for dose response does not account for strain or serotype variability in pathogenicity and virulence, other than perhaps, recognizing the existence of avirulent strains. However, an examination of data sets from human clinical trials in which Salmonella spp. and Campylobacter jejuni strains were administered reveals significant strain differences. This article discusses the evidence for strain variability and concludes that more biologically based alternatives are necessary to replace the default assumptions commonly used in microbial risk assessment, specifically regarding strain variability.

Specification of ISS Plasma Environment Variability

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Neergaard, Linda F.; Bui, Them H.; Mikatarian, Ronald R.; Barsamian, H.; Koontz, Steven L.

2004-01-01

Quantifying spacecraft charging risks and associated hazards for the International Space Station (ISS) requires a plasma environment specification for the natural variability of ionospheric temperature (Te) and density (Ne). Empirical ionospheric specification and forecast models such as the International Reference Ionosphere (IRI) model typically only provide long term (seasonal) mean Te and Ne values for the low Earth orbit environment. This paper describes a statistical analysis of historical ionospheric low Earth orbit plasma measurements from the AE-C, AE-D, and DE-2 satellites used to derive a model of deviations of observed data values from IRI-2001 estimates of Ne, Te parameters for each data point to provide a statistical basis for modeling the deviations of the plasma environment from the IRI model output. Application of the deviation model with the IRI-2001 output yields a method for estimating extreme environments for the ISS spacecraft charging analysis.

A novel porous framework as variable chemo-sensor: from response of specific carcinogenic alkyl-aromatic to selective detection of explosive nitro-aromatics.

PubMed

Chen, Qihui

2018-06-07

Selective probing one molecule from one class similar molecules is highly challenging due to their similar chemical and physical properties. Here, a novel metal-organic framework FJI-H15 with flexible porous cages has been designed and synthesized, which can specifically recognize ethyl-benzene with ultrahigh enhancement efficiency from series of alkyl-aromatics, in which an unusual size-dependent interaction has been found and proved. While it also can selectively detect phenolic-nitroaromatics among series of nitro-aromatics based on energy transferring and electrostatic interaction. Such unusual specificity and variable mechanisms responding to different type molecules has not been reported, which will provide a new strategy for developing more effective chemo-sensor based on MOFs for probing small structural differences in molecules. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Learning Instance-Specific Predictive Models

PubMed Central

Visweswaran, Shyam; Cooper, Gregory F.

2013-01-01

This paper introduces a Bayesian algorithm for constructing predictive models from data that are optimized to predict a target variable well for a particular instance. This algorithm learns Markov blanket models, carries out Bayesian model averaging over a set of models to predict a target variable of the instance at hand, and employs an instance-specific heuristic to locate a set of suitable models to average over. We call this method the instance-specific Markov blanket (ISMB) algorithm. The ISMB algorithm was evaluated on 21 UCI data sets using five different performance measures and its performance was compared to that of several commonly used predictive algorithms, including nave Bayes, C4.5 decision tree, logistic regression, neural networks, k-Nearest Neighbor, Lazy Bayesian Rules, and AdaBoost. Over all the data sets, the ISMB algorithm performed better on average on all performance measures against all the comparison algorithms. PMID:25045325

Familial cancer syndromes and clusters.

PubMed

Birch, J M

1994-07-01

The study of rare families in which a variety of cancers occur, usually at an early age and with patterns consistent with a common hereditary mechanism, has contributed much to our understanding of the process of carcinogenesis. So far, genes identified as having a role in cancer predisposition in these families have also been important in the histogenesis of sporadic cancers. In the two most clearly defined cancer family syndromes, the Li-Fraumeni syndrome and Lynch syndrome II, the genes involved predispose to diverse but specific constellations of cancers. Genes associated with site-specific familial cancer clusters may also give rise to increased susceptibility to other cancers, and site-specific clusters may represent one end of a spectrum. A consistent feature of familial cancer syndromes is the variable expression within and between families. A challenge for the future will be to determine other factors which may interact with the principal genes involved, giving rise to this variability.

Rapid isolation of IgNAR variable single-domain antibody fragments from a shark synthetic library.

PubMed

Shao, Cui-Ying; Secombes, Chris J; Porter, Andrew J

2007-01-01

The immunoglobulin isotype IgNAR (Novel Antigen Receptor) was discovered in the serum of the nurse shark (Ginglymostoma cirratum) and wobbegong shark (Orectolobus maculates) as a homodimer of two protein chains, each composed of a single variable domain (V) domain and five constant domains. The IgNAR variable domain contains an intact antigen-binding site and functions as an independent domain able to react to antigen with both high specificity and affinity. Here we describe the successful construction of a synthetic phage-displayed library based upon a single anti-lysozyme clone HEL-5A7 scaffold, which was previously selected from an immune IgNAR variable domain library. The complementarity-determining region 3 (CDR3) loop of this clone was varied in both length and composition and the derived library was used to pan against two model proteins, lysozyme and leptin. A single anti-lysozyme clone (Ly-X20) and anti-leptin clone (Lep-12E1) were selected for further study. Both clones were shown to be functionally expressed in Escherichia coli, extremely thermostable and bind to corresponding antigens specifically. The results here demonstrate that a synthetic IgNAR variable domain library based on a single framework scaffold can be used as a route to generate antigen binders quickly, easily and without the need of immunization.

Modelling the meteorological forest fire niche in heterogeneous pyrologic conditions.

PubMed

De Angelis, Antonella; Ricotta, Carlo; Conedera, Marco; Pezzatti, Gianni Boris

2015-01-01

Fire regimes are strongly related to weather conditions that directly and indirectly influence fire ignition and propagation. Identifying the most important meteorological fire drivers is thus fundamental for daily fire risk forecasting. In this context, several fire weather indices have been developed focussing mainly on fire-related local weather conditions and fuel characteristics. The specificity of the conditions for which fire danger indices are developed makes its direct transfer and applicability problematic in different areas or with other fuel types. In this paper we used the low-to-intermediate fire-prone region of Canton Ticino as a case study to develop a new daily fire danger index by implementing a niche modelling approach (Maxent). In order to identify the most suitable weather conditions for fires, different combinations of input variables were tested (meteorological variables, existing fire danger indices or a combination of both). Our findings demonstrate that such combinations of input variables increase the predictive power of the resulting index and surprisingly even using meteorological variables only allows similar or better performances than using the complex Canadian Fire Weather Index (FWI). Furthermore, the niche modelling approach based on Maxent resulted in slightly improved model performance and in a reduced number of selected variables with respect to the classical logistic approach. Factors influencing final model robustness were the number of fire events considered and the specificity of the meteorological conditions leading to fire ignition.

Modelling the Meteorological Forest Fire Niche in Heterogeneous Pyrologic Conditions

PubMed Central

De Angelis, Antonella; Ricotta, Carlo; Conedera, Marco; Pezzatti, Gianni Boris

2015-01-01

Fire regimes are strongly related to weather conditions that directly and indirectly influence fire ignition and propagation. Identifying the most important meteorological fire drivers is thus fundamental for daily fire risk forecasting. In this context, several fire weather indices have been developed focussing mainly on fire-related local weather conditions and fuel characteristics. The specificity of the conditions for which fire danger indices are developed makes its direct transfer and applicability problematic in different areas or with other fuel types. In this paper we used the low-to-intermediate fire-prone region of Canton Ticino as a case study to develop a new daily fire danger index by implementing a niche modelling approach (Maxent). In order to identify the most suitable weather conditions for fires, different combinations of input variables were tested (meteorological variables, existing fire danger indices or a combination of both). Our findings demonstrate that such combinations of input variables increase the predictive power of the resulting index and surprisingly even using meteorological variables only allows similar or better performances than using the complex Canadian Fire Weather Index (FWI). Furthermore, the niche modelling approach based on Maxent resulted in slightly improved model performance and in a reduced number of selected variables with respect to the classical logistic approach. Factors influencing final model robustness were the number of fire events considered and the specificity of the meteorological conditions leading to fire ignition. PMID:25679957

Studies of educational interventions and outcomes in diabetic adults: a meta-analysis revisited.

PubMed

Brown, S A

1990-12-01

This paper reports a follow-up of previous meta-analysis research conducted by the author on the effects of diabetes patient education on patient outcomes. An expanded sample of studies and psychological outcome variables were added to the previously studied variables of patient knowledge, self-care behaviors (compliance and skill performance) and metabolic control. The purpose was to determine: (1) the effects of patient education on specific outcome variables; and (2) the relationships between effects of education and characteristics of the studies and/or subjects. Following an extensive literature search, a total of 82 studies were found which met the inclusion criteria for this analysis; 68% were published and 32% were unpublished. Homogeneity analyses of specific patient outcome variables yielded the following results: knowledge effects ranged from 0.49 to 1.05; self-care behavior effects from 0.17 to 0.57, with insulin injection and weight loss associated with the smallest effect sizes; metabolic control from 0.16 to 0.41; and psychological outcomes 0.27. Mean age of the subjects was negatively correlated with knowledge and cholesterol, indicating that the older the mean age of the subjects, the lower the effects of patient education on these variables. Findings of this meta-analysis on the expanded data set were consistent with the previous meta-analysis and lend support to the effectiveness of diabetes patient education in improving patient outcomes.

Convection in the Rayleigh-Bénard flow with all fluid properties variable

NASA Astrophysics Data System (ADS)

Sassos, Athanasios; Pantokratoras, Asterios

2011-10-01

In the present paper, the effect of variable fluid properties (density, viscosity, thermal conductivity and specific heat) on the convection in the classical Rayleigh-Bénard problem is investigated. The investigation concerns water, air, and engine oil by taking into account the variation of fluid properties with temperature. The results are obtained by numerically solving the governing equations, using the SIMPLE algorithm and covering large temperature differences. It is found that the critical Rayleigh number increases as the temperature difference increases considering all fluid properties variable. However, when the fluid properties are kept constant, calculated at the mean temperature, and only density is considered variable, the critical Rayleigh number either decreases or remains constant.

Sustainability knowledge using “AKASA” model among architecture students from Klang Valley private universities, Malaysia.

NASA Astrophysics Data System (ADS)

Kuppusamy, Sivaraman; Faris Khamidi, Mohd; Sheng, Lee Xia; Salvi Mari, Tamil

2017-12-01

The study intend to investigate sustainability knowledge using “AKASA” model. This model comprises all the literacy level which is the awareness, knowledge, attitude, skills and action. 234 students from 5 selected private universities were surveyed using questionnaires. Students were specifically selected from year 2 and year 3 from private universities in Klang valley, Malaysia. The study intends to investigate the environmental literacy level specifically the knowledge variable. The parametric study was conducted with descriptive analysis and the results shows that the environmental knowledge is at high level compared to other environmental literacy variables among year 2, year 3 and combine year 2 and year 3.

Developmental Trajectories in Toddlers’ Self-restraint Predict Individual Differences in Executive Functions 14 Years Later: A Behavioral Genetic Analysis

PubMed Central

Friedman, Naomi P.; Miyake, Akira; Robinson, JoAnn L.; Hewitt, John K.

2011-01-01

We examined whether self-restraint in early childhood predicted individual differences in three executive functions (EFs; inhibiting prepotent responses, updating working memory, and shifting task sets) in late adolescence in a sample of ~950 twins. At ages 14, 20, 24, and 36 months, the children were shown an attractive toy and told not to touch it for 30 seconds. Latency to touch the toy increased with age, and latent class growth modeling distinguished two groups of children that differed in their latencies to touch the toy at all 4 time points. Using confirmatory factor analysis, the three EFs (measured with latent variables at age 17 years) were decomposed into a Common EF factor (isomorphic to response inhibition ability) and two factors specific to updating and shifting, respectively. Less restrained children had significantly lower scores on the Common EF factor, equivalent scores on the Updating-specific factor, and higher scores on the Shifting-specific factor than the more restrained children. The less restrained group also had lower IQ scores, but this effect was entirely mediated by the EF components. Twin models indicated that the associations were primarily genetic in origin for the Common EF variable but split between genetics and nonshared environment for the Shifting-specific variable. These results suggest a biological relation between individual differences in self-restraint and EFs, one that begins early in life and persists into late adolescence. PMID:21668099

Insomnia in patients with chronic tinnitus: Cognitive and emotional distress as moderator variables.

PubMed

Crönlein, Tatjana; Langguth, Berthold; Pregler, Maximilian; Kreuzer, Peter M; Wetter, Thomas C; Schecklmann, Martin

2016-04-01

Tinnitus is often associated with disturbed sleep, but there are also patients without sleep problems. The mechanisms for developing insomnia or not in tinnitus patients are still unknown. The aim of the present study was to extract possible tinnitus specific factors that increase the risk of developing insomnia based on the analysis of a large patient cohort suffering from chronic tinnitus. 173 patients presenting at the multidisciplinary tinnitus center of a University Hospital completed a questionnaire measuring specific psychological symptoms of insomnia (RIS) and a tinnitus questionnaire (TQ). The scores of all ten RIS items were compared between tinnitus patients and 94 healthy individuals by separate ANOVAs in order to specify the extent of insomnia specific symptoms in the tinnitus group. In a second step a multiple linear regression analysis was performed in the tinnitus sample with subscales of the TQ (excluding the TQ sleep scale), age and duration of tinnitus as independent variables and the RIS score as the dependent variables. Tinnitus patients differed from healthy controls not only in impaired sleep quality but also in insomnia specific concerns and anxiety. Tinnitus related emotional and cognitive distress and somatic complaints correlated with severity of insomnia, whereas no association of age or duration of tinnitus with severity of insomnia was found. Our results suggest that chronic tinnitus patients have more sleeping difficulties and associated worries about sleep or negative emotions in contrast to healthy controls. Tinnitus-related distress is related to insomnia. Copyright © 2016. Published by Elsevier Inc.

Separating Common from Unique Variance Within Emotional Distress: An Examination of Reliability and Relations to Worry.

PubMed

Marshall, Andrew J; Evanovich, Emma K; David, Sarah Jo; Mumma, Gregory H

2018-01-17

High comorbidity rates among emotional disorders have led researchers to examine transdiagnostic factors that may contribute to shared psychopathology. Bifactor models provide a unique method for examining transdiagnostic variables by modelling the common and unique factors within measures. Previous findings suggest that the bifactor model of the Depression Anxiety and Stress Scale (DASS) may provide a method for examining transdiagnostic factors within emotional disorders. This study aimed to replicate the bifactor model of the DASS, a multidimensional measure of psychological distress, within a US adult sample and provide initial estimates of the reliability of the general and domain-specific factors. Furthermore, this study hypothesized that Worry, a theorized transdiagnostic variable, would show stronger relations to general emotional distress than domain-specific subscales. Confirmatory factor analysis was used to evaluate the bifactor model structure of the DASS in 456 US adult participants (279 females and 177 males, mean age 35.9 years) recruited online. The DASS bifactor model fitted well (CFI = 0.98; RMSEA = 0.05). The General Emotional Distress factor accounted for most of the reliable variance in item scores. Domain-specific subscales accounted for modest portions of reliable variance in items after accounting for the general scale. Finally, structural equation modelling indicated that Worry was strongly predicted by the General Emotional Distress factor. The DASS bifactor model is generalizable to a US community sample and General Emotional Distress, but not domain-specific factors, strongly predict the transdiagnostic variable Worry.

Boosting multi-state models.

PubMed

Reulen, Holger; Kneib, Thomas

2016-04-01

One important goal in multi-state modelling is to explore information about conditional transition-type-specific hazard rate functions by estimating influencing effects of explanatory variables. This may be performed using single transition-type-specific models if these covariate effects are assumed to be different across transition-types. To investigate whether this assumption holds or whether one of the effects is equal across several transition-types (cross-transition-type effect), a combined model has to be applied, for instance with the use of a stratified partial likelihood formulation. Here, prior knowledge about the underlying covariate effect mechanisms is often sparse, especially about ineffectivenesses of transition-type-specific or cross-transition-type effects. As a consequence, data-driven variable selection is an important task: a large number of estimable effects has to be taken into account if joint modelling of all transition-types is performed. A related but subsequent task is model choice: is an effect satisfactory estimated assuming linearity, or is the true underlying nature strongly deviating from linearity? This article introduces component-wise Functional Gradient Descent Boosting (short boosting) for multi-state models, an approach performing unsupervised variable selection and model choice simultaneously within a single estimation run. We demonstrate that features and advantages in the application of boosting introduced and illustrated in classical regression scenarios remain present in the transfer to multi-state models. As a consequence, boosting provides an effective means to answer questions about ineffectiveness and non-linearity of single transition-type-specific or cross-transition-type effects.

Scrub typhus in South India: clinical and laboratory manifestations, genetic variability, and outcome.

PubMed

Varghese, George M; Janardhanan, Jeshina; Trowbridge, Paul; Peter, John V; Prakash, John A J; Sathyendra, Sowmya; Thomas, Kurien; David, Thambu S; Kavitha, M L; Abraham, Ooriapadickal C; Mathai, Dilip

2013-11-01

This study sought to document the clinical and laboratory manifestations, genetic variability, and outcomes of scrub typhus, an often severe infection caused by Orientia tsutsugamushi, in South India. Patients admitted to a large teaching hospital with IgM ELISA-confirmed scrub typhus were evaluated. Clinical examination with a thorough search for an eschar, laboratory testing, chest X-ray, and outcome were documented and analyzed. Additionally, a 410-bp region of the 56-kDa type-specific antigen gene of O. tsutsugamushi was sequenced and compared with isolates from other regions of Asia. Most of the 154 patients evaluated presented with fever and non-specific symptoms. An eschar was found in 86 (55%) patients. Mild hepatic involvement was seen in most, with other organ involvement including respiratory, cardiovascular, and renal. Multi-organ dysfunction was noted in 59 (38.3%), and the fatality rate was 7.8%. Hypotension requiring vasoactive agents was found to be an independent predictor of mortality (p<0.001). The phylogeny of 26 samples showed 17 (65%) clustering with the Kato-like group and eight (31%) with the Karp-like group. The presentation of scrub typhus can be variable, often non-specific, but with potentially severe multi-organ dysfunction. Prompt recognition is key to specific treatment and good outcomes. Further study of the circulating strains is essential for the development of a successful vaccine and sensitive point-of-care testing. Copyright © 2013 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Cognitive correlates of white matter lesion load and brain atrophy

PubMed Central

Dong, Chuanhui; Nabizadeh, Nooshin; Caunca, Michelle; Cheung, Ying Kuen; Rundek, Tatjana; Elkind, Mitchell S.V.; DeCarli, Charles; Sacco, Ralph L.; Stern, Yaakov

2015-01-01

Objective: We investigated white matter lesion load and global and regional brain volumes in relation to domain-specific cognitive performance in the stroke-free Northern Manhattan Study (NOMAS) population. Methods: We quantified white matter hyperintensity volume (WMHV), total cerebral volume (TCV), and total lateral ventricular (TLV) volume, as well as hippocampal and cortical gray matter (GM) lobar volumes in a subgroup. We used general linear models to examine MRI markers in relation to domain-specific cognitive performance, adjusting for key covariates. Results: MRI and cognitive data were available for 1,163 participants (mean age 70 ± 9 years; 60% women; 66% Hispanic, 17% black, 15% white). Across the entire sample, those with greater WMHV had worse processing speed. Those with larger TLV volume did worse on episodic memory, processing speed, and semantic memory tasks, and TCV did not explain domain-specific variability in cognitive performance independent of other measures. Age was an effect modifier, and stratified analysis showed that TCV and WMHV explained variability in some domains above age 70. Smaller hippocampal volume was associated with worse performance across domains, even after adjusting for APOE ε4 and vascular risk factors, whereas smaller frontal lobe volumes were only associated with worse executive function. Conclusions: In this racially/ethnically diverse, community-based sample, white matter lesion load was inversely associated with cognitive performance, independent of brain atrophy. Lateral ventricular, hippocampal, and lobar GM volumes explained domain-specific variability in cognitive performance. PMID:26156514

Commitment to personal values and guilt feelings in dementia caregivers.

PubMed

Gallego-Alberto, Laura; Losada, Andrés; Márquez-González, María; Romero-Moreno, Rosa; Vara, Carlos

2017-01-01

Caregivers' commitment to personal values is linked to caregivers' well-being, although the effects of personal values on caregivers' guilt have not been explored to date. The goal of this study is to analyze the relationship between caregivers´ commitment to personal values and guilt feelings. Participants were 179 dementia family caregivers. Face-to-face interviews were carried out to describe sociodemographic variables and assess stressors, caregivers' commitment to personal values and guilt feelings. Commitment to values was conceptualized as two factors (commitment to own values and commitment to family values) and 12 specific individual values (e.g. education, family or caregiving role). Hierarchical regressions were performed controlling for sociodemographic variables and stressors, and introducing the two commitment factors (in a first regression) or the commitment to individual/specific values (in a second regression) as predictors of guilt. In terms of the commitment to values factors, the analyzed regression model explained 21% of the variance of guilt feelings. Only the factor commitment to family values contributed significantly to the model, explaining 7% of variance. With regard to the regression analyzing the contribution of specific values to caregivers' guilt, commitment to the caregiving role and with leisure contributed negatively and significantly to the explanation of caregivers' guilt. Commitment to work contributed positively to guilt feelings. The full model explained 30% of guilt feelings variance. The specific values explained 16% of the variance. Our findings suggest that commitment to personal values is a relevant variable to understand guilt feelings in caregivers.

High stimulus variability in nonnative speech learning supports formation of abstract categories: evidence from Japanese geminates.

PubMed

Sadakata, Makiko; McQueen, James M

2013-08-01

This study reports effects of a high-variability training procedure on nonnative learning of a Japanese geminate-singleton fricative contrast. Thirty native speakers of Dutch took part in a 5-day training procedure in which they identified geminate and singleton variants of the Japanese fricative /s/. Participants were trained with either many repetitions of a limited set of words recorded by a single speaker (low-variability training) or with fewer repetitions of a more variable set of words recorded by multiple speakers (high-variability training). Both types of training enhanced identification of speech but not of nonspeech materials, indicating that learning was domain specific. High-variability training led to superior performance in identification but not in discrimination tests, and supported better generalization of learning as shown by transfer from the trained fricatives to the identification of untrained stops and affricates. Variability thus helps nonnative listeners to form abstract categories rather than to enhance early acoustic analysis.

FTP Extensions for Variable Protocol Specification

NASA Technical Reports Server (NTRS)

Allman, Mark; Ostermann, Shawn

2000-01-01

The specification for the File Transfer Protocol (FTP) assumes that the underlying network protocols use a 32-bit network address and a 16-bit transport address (specifically IP version 4 and TCP). With the deployment of version 6 of the Internet Protocol, network addresses will no longer be 32-bits. This paper species extensions to FTP that will allow the protocol to work over a variety of network and transport protocols.

Effects of practice schedule and task specificity on the adaptive process of motor learning.

PubMed

Barros, João Augusto de Camargo; Tani, Go; Corrêa, Umberto Cesar

2017-10-01

This study investigated the effects of practice schedule and task specificity based on the perspective of adaptive process of motor learning. For this purpose, tasks with temporal and force control learning requirements were manipulated in experiments 1 and 2, respectively. Specifically, the task consisted of touching with the dominant hand the three sequential targets with specific movement time or force for each touch. Participants were children (N=120), both boys and girls, with an average age of 11.2years (SD=1.0). The design in both experiments involved four practice groups (constant, random, constant-random, and random-constant) and two phases (stabilisation and adaptation). The dependent variables included measures related to the task goal (accuracy and variability of error of the overall movement and force patterns) and movement pattern (macro- and microstructures). Results revealed a similar error of the overall patterns for all groups in both experiments and that they adapted themselves differently in terms of the macro- and microstructures of movement patterns. The study concludes that the effects of practice schedules on the adaptive process of motor learning were both general and specific to the task. That is, they were general to the task goal performance and specific regarding the movement pattern. Copyright © 2017 Elsevier B.V. All rights reserved.

Screening and identification of human ZnT8-specific single-chain variable fragment (scFv) from type 1 diabetes phage display library.

PubMed

Wu, Qian; Wang, Xiaodong; Gu, Yong; Zhang, Xiao; Qin, Yao; Chen, Heng; Xu, Xinyu; Yang, Tao; Zhang, Mei

2016-07-01

Zinc transporter 8 (ZnT8) is a major autoantigen and a predictive marker in type 1 diabetes (T1D). To investigate ZnT8-specific antibodies, a phage display library from T1D was constructed and single-chain antibodies against ZnT8 were screened and identified. Human T1D single-chain variable fragment (scFv) phage display library consists of approximately 1×10(8) clones. After four rounds of bio-panning, seven unique clones were positive by phage ELISA. Among them, C27 and C22, which demonstrated the highest affinity to ZnT8, were expressed in Escherichia coli Top10F' and then purified by affinity chromatography. C27 and C22 specifically bound ZnT8 N/C fusion protein and ZnT8 C terminal dimer with one Arg325Trp mutation. The specificity to human islet cells of these scFvs were further confirmed by immunohistochemistry. In conclusion, we have successfully constructed a T1D phage display antibody library and identified two ZnT8-specific scFv clones, C27 and C22. These ZnT8-specific scFvs are potential agents in immunodiagnostic and immunotherapy of T1D.

Comparison of taxon-specific versus general locus sets for targeted sequence capture in plant phylogenomics.

PubMed

Chau, John H; Rahfeldt, Wolfgang A; Olmstead, Richard G

2018-03-01

Targeted sequence capture can be used to efficiently gather sequence data for large numbers of loci, such as single-copy nuclear loci. Most published studies in plants have used taxon-specific locus sets developed individually for a clade using multiple genomic and transcriptomic resources. General locus sets can also be developed from loci that have been identified as single-copy and have orthologs in large clades of plants. We identify and compare a taxon-specific locus set and three general locus sets (conserved ortholog set [COSII], shared single-copy nuclear [APVO SSC] genes, and pentatricopeptide repeat [PPR] genes) for targeted sequence capture in Buddleja (Scrophulariaceae) and outgroups. We evaluate their performance in terms of assembly success, sequence variability, and resolution and support of inferred phylogenetic trees. The taxon-specific locus set had the most target loci. Assembly success was high for all locus sets in Buddleja samples. For outgroups, general locus sets had greater assembly success. Taxon-specific and PPR loci had the highest average variability. The taxon-specific data set produced the best-supported tree, but all data sets showed improved resolution over previous non-sequence capture data sets. General locus sets can be a useful source of sequence capture targets, especially if multiple genomic resources are not available for a taxon.

Exploring the full natural variability of eruption sizes within probabilistic hazard assessment of tephra dispersal

NASA Astrophysics Data System (ADS)

Selva, Jacopo; Sandri, Laura; Costa, Antonio; Tonini, Roberto; Folch, Arnau; Macedonio, Giovanni

2014-05-01

The intrinsic uncertainty and variability associated to the size of next eruption strongly affects short to long-term tephra hazard assessment. Often, emergency plans are established accounting for the effects of one or a few representative scenarios (meant as a specific combination of eruptive size and vent position), selected with subjective criteria. On the other hand, probabilistic hazard assessments (PHA) consistently explore the natural variability of such scenarios. PHA for tephra dispersal needs the definition of eruptive scenarios (usually by grouping possible eruption sizes and vent positions in classes) with associated probabilities, a meteorological dataset covering a representative time period, and a tephra dispersal model. PHA results from combining simulations considering different volcanological and meteorological conditions through a weight given by their specific probability of occurrence. However, volcanological parameters, such as erupted mass, eruption column height and duration, bulk granulometry, fraction of aggregates, typically encompass a wide range of values. Because of such a variability, single representative scenarios or size classes cannot be adequately defined using single values for the volcanological inputs. Here we propose a method that accounts for this within-size-class variability in the framework of Event Trees. The variability of each parameter is modeled with specific Probability Density Functions, and meteorological and volcanological inputs are chosen by using a stratified sampling method. This procedure allows avoiding the bias introduced by selecting single representative scenarios and thus neglecting most of the intrinsic eruptive variability. When considering within-size-class variability, attention must be paid to appropriately weight events falling within the same size class. While a uniform weight to all the events belonging to a size class is the most straightforward idea, this implies a strong dependence on the thresholds dividing classes: under this choice, the largest event of a size class has a much larger weight than the smallest event of the subsequent size class. In order to overcome this problem, in this study, we propose an innovative solution able to smoothly link the weight variability within each size class to the variability among the size classes through a common power law, and, simultaneously, respect the probability of different size classes conditional to the occurrence of an eruption. Embedding this procedure into the Bayesian Event Tree scheme enables for tephra fall PHA, quantified through hazard curves and maps representing readable results applicable in planning risk mitigation actions, and for the quantification of its epistemic uncertainties. As examples, we analyze long-term tephra fall PHA at Vesuvius and Campi Flegrei. We integrate two tephra dispersal models (the analytical HAZMAP and the numerical FALL3D) into BET_VH. The ECMWF reanalysis dataset are used for exploring different meteorological conditions. The results obtained clearly show that PHA accounting for the whole natural variability significantly differs from that based on a representative scenarios, as in volcanic hazard common practice.

Strategies and methods to study female-specific cardiovascular health and disease: a guide for clinical scientists.

PubMed

Ouyang, Pamela; Wenger, Nanette K; Taylor, Doris; Rich-Edwards, Janet W; Steiner, Meir; Shaw, Leslee J; Berga, Sarah L; Miller, Virginia M; Merz, Noel Bairey

2016-01-01

In 2001, the Institute of Medicine's (IOM) report, "Exploring the Biological Contributions to Human Health: Does Sex Matter?" advocated for better understanding of the differences in human diseases between the sexes, with translation of these differences into clinical practice. Sex differences are well documented in the prevalence of cardiovascular (CV) risk factors, the clinical manifestation and incidence of cardiovascular disease (CVD), and the impact of risk factors on outcomes. There are also physiologic and psychosocial factors unique to women that may affect CVD risk, such as issues related to reproduction. The Society for Women's Health Research (SWHR) CV Network compiled an inventory of sex-specific strategies and methods for the study of women and CV health and disease across the lifespan. References for methods and strategy details are provided to gather and evaluate this information. Some items comprise robust measures; others are in development. To address female-specific CV health and disease in population, physiology, and clinical trial research, data should be collected on reproductive history, psychosocial variables, and other factors that disproportionately affect CVD in women. Variables related to reproductive health include the following: age of menarche, menstrual cycle regularity, hormone levels, oral contraceptive use, pregnancy history/complications, polycystic ovary syndrome (PCOS) components, menopause age, and use and type of menopausal hormone therapy. Other factors that differentially affect women's CV risk include diabetes mellitus, autoimmune inflammatory disease, and autonomic vasomotor control. Sex differences in aging as well as psychosocial variables such as depression and stress should also be considered. Women are frequently not included/enrolled in mixed-sex CVD studies; when they are included, information on these variables is generally not collected. These omissions limit the ability to determine the role of sex-specific contributors to CV health and disease. Lack of sex-specific knowledge contributes to the CVD health disparities that women face. The purpose of this review is to encourage investigators to consider ways to increase the usefulness of physiological and psychosocial data obtained from clinical populations, in an effort to improve the understanding of sex differences in clinical CVD research and health-care delivery for women and men.

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

Klima, Matej; Kucharik, MIlan; Shashkov, Mikhail Jurievich

We analyze several new and existing approaches for limiting tensor quantities in the context of deviatoric stress remapping in an ALE numerical simulation of elastic flow. Remapping and limiting of the tensor component-by-component is shown to violate radial symmetry of derived variables such as elastic energy or force. Therefore, we have extended the symmetry-preserving Vector Image Polygon algorithm, originally designed for limiting vector variables. This limiter constrains the vector (in our case a vector of independent tensor components) within the convex hull formed by the vectors from surrounding cells – an equivalent of the discrete maximum principle in scalar variables.more » We compare this method with a limiter designed specifically for deviatoric stress limiting which aims to constrain the J 2 invariant that is proportional to the specific elastic energy and scale the tensor accordingly. We also propose a method which involves remapping and limiting the J 2 invariant independently using known scalar techniques. The deviatoric stress tensor is then scaled to match this remapped invariant, which guarantees conservation in terms of elastic energy.« less

Selection and characterization of naturally occurring single-domain (IgNAR) antibody fragments from immunized sharks by phage display.

PubMed

Dooley, Helen; Flajnik, Martin F; Porter, Andrew J

2003-09-01

The novel immunoglobulin isotype novel antigen receptor (IgNAR) is found in cartilaginous fish and is composed of a heavy-chain homodimer that does not associate with light chains. The variable regions of IgNAR function as independent domains similar to those found in the heavy-chain immunoglobulins of Camelids. Here, we describe the successful cloning and generation of a phage-displayed, single-domain library based upon the variable domain of IgNAR. Selection of such a library generated from nurse sharks (Ginglymostoma cirratum) immunized with the model antigen hen egg-white lysozyme (HEL) enabled the successful isolation of intact antigen-specific binders matured in vivo. The selected variable domains were shown to be functionally expressed in Escherichia coli, extremely stable, and bind to antigen specifically with an affinity in the nanomolar range. This approach can therefore be considered as an alternative route for the isolation of minimal antigen-binding fragments with favorable characteristics.

Associations between race, sex and immune response variations to rubella vaccination in two independent cohorts

PubMed Central

Haralambieva, Iana H.; Salk, Hannah M.; Lambert, Nathaniel D.; Ovsyannikova, Inna G.; Kennedy, Richard B.; Warner, Nathaniel D.; Pankratz, V.Shane; Poland, Gregory A.

2014-01-01

Introduction Immune response variations after vaccination are influenced by host genetic factors and demographic variables, such as race, ethnicity and sex. The latter have not been systematically studied in regard to live rubella vaccine, but are of interest for developing next generation vaccines for diverse populations, for predicting immune responses after vaccination, and for better understanding the variables that impact immune response. Methods We assessed associations between demographic variables, including race, ethnicity and sex, and rubella-specific neutralizing antibody levels and secreted cytokines (IFN! , IL-6) in two independent cohorts (1,994 subjects), using linear and linear mixed models approaches, and genetically defined racial and ethnic categorizations. Results Our replicated findings in two independent, large, racially diverse cohorts indicate that individuals of African descent have significantly higher rubella-specific neutralizing antibody levels compared to individuals of European descent and/or Hispanic ethnicity (p! 0.001). Conclusion Our study provides consistent evidence for racial/ethnic differences in humoral immune response following rubella vaccination. PMID:24530932

Evolution of Alternative Adaptive Immune Systems in Vertebrates.

PubMed

Boehm, Thomas; Hirano, Masayuki; Holland, Stephen J; Das, Sabyasachi; Schorpp, Michael; Cooper, Max D

2018-04-26

Adaptive immunity in jawless fishes is based on antigen recognition by three types of variable lymphocyte receptors (VLRs) composed of variable leucine-rich repeats, which are differentially expressed by two T-like lymphocyte lineages and one B-like lymphocyte lineage. The T-like cells express either VLRAs or VLRCs of yet undefined antigen specificity, whereas the VLRB antibodies secreted by B-like cells bind proteinaceous and carbohydrate antigens. The incomplete VLR germline genes are assembled into functional units by a gene conversion-like mechanism that employs flanking variable leucine-rich repeat sequences as templates in association with lineage-specific expression of cytidine deaminases. B-like cells develop in the hematopoietic typhlosole and kidneys, whereas T-like cells develop in the thymoid, a thymus-equivalent region at the gill fold tips. Thus, the dichotomy between T-like and B-like cells and the presence of dedicated lymphopoietic tissues emerge as ancestral vertebrate features, whereas the somatic diversification of structurally distinct antigen receptor genes evolved independently in jawless and jawed vertebrates.

Oxytocin receptor gene polymorphism modulates the effects of social support on heart rate variability

PubMed Central

Kanthak, Magdalena K.; Chen, Frances S.; Kumsta, Robert; Hill, LaBarron K.; Thayer, Julian F.; Heinrichs, Markus

2017-01-01

A large body of empirical research has demonstrated stress-buffering effects of social support. However, recent studies suggest that genetic variation of the oxytocin system (specifically, a common single nucleotide polymorphism, rs53576, of the oxytocin receptor gene) modulates the efficacy of social support. The timing and neurobiological basis of this genetic modulation were investigated using a standardized, laboratory-based psychological stress procedure (Trier Social Stress Test for Groups, TSST-G). To index potential stress buffering effects of social support mediated by the oxytocin system, heart rate variability (HRV) was obtained before and during the TSST-G from 40 healthy participants. Results indicate that social support is associated with higher HRV only in G allele carriers. Specifically, social support increased heart rate variability during direct social interaction and only in individuals with at least one copy of the G allele of rs53576. These findings support the idea that the stress-attenuating effects of social support are modulated by genetic variation of the oxytocin system. PMID:26903384

A diagnostic model for chronic hypersensitivity pneumonitis

PubMed Central

Johannson, Kerri A; Elicker, Brett M; Vittinghoff, Eric; Assayag, Deborah; de Boer, Kaïssa; Golden, Jeffrey A; Jones, Kirk D; King, Talmadge E; Koth, Laura L; Lee, Joyce S; Ley, Brett; Wolters, Paul J; Collard, Harold R

2017-01-01

The objective of this study was to develop a diagnostic model that allows for a highly specific diagnosis of chronic hypersensitivity pneumonitis using clinical and radiological variables alone. Chronic hypersensitivity pneumonitis and other interstitial lung disease cases were retrospectively identified from a longitudinal database. High-resolution CT scans were blindly scored for radiographic features (eg, ground-glass opacity, mosaic perfusion) as well as the radiologist’s diagnostic impression. Candidate models were developed then evaluated using clinical and radiographic variables and assessed by the cross-validated C-statistic. Forty-four chronic hypersensitivity pneumonitis and eighty other interstitial lung disease cases were identified. Two models were selected based on their statistical performance, clinical applicability and face validity. Key model variables included age, down feather and/or bird exposure, radiographic presence of ground-glass opacity and mosaic perfusion and moderate or high confidence in the radiographic impression of chronic hypersensitivity pneumonitis. Models were internally validated with good performance, and cut-off values were established that resulted in high specificity for a diagnosis of chronic hypersensitivity pneumonitis. PMID:27245779

A model to assess lactic acid bacteria aminopeptidase activities in Parmigiano Reggiano cheese during ripening.

PubMed

Gatti, M; De Dea Lindner, J; Gardini, F; Mucchetti, G; Bevacqua, D; Fornasari, M E; Neviani, E

2008-11-01

The aim of this work was to investigate in which phases of ripening of Parmigiano Reggiano cheese lactic acid bacteria aminopeptidases present in cheese extract could be involved in release of free amino acids and to better understand the behavior of these enzymes in physical-chemical conditions that are far from their optimum. In particular, we evaluated 6 different substrates to reproduce broad-specificity aminopeptidase N, broad-specificity aminopeptidase C, glutamyl aminopeptidase A, peptidase with high specificity for leucine and alanine, proline iminopeptidase, and X-prolyl dipeptidyl aminopeptidase activities releasing different N-terminal amino acids. The effects of pH, NaCl concentration, and temperature on the enzyme activities of amino acid beta-naphthylamide (betaNA)-substrates were determined by modulating the variables in 19 different runs of an experimental design, which allowed the building of mathematical models able to assess the effect on aminopeptidases activities over a range of values, obtained with bibliographic data, covering different environmental conditions in different zones of the cheese wheel at different aging times. The aminopeptidases tested in this work were present in cell-free Parmigiano Reggiano cheese extract after a 17-mo ripening and were active when tested in model system. The modeling approach shows that to highlight the individual and interactive effects of chemical-physical variables on enzyme activities, it is helpful to determine the true potential of an amino-peptidase in cheese. Our results evidenced that the 6 different lactic acid bacteria peptidases participate in cheese proteolysis and are induced or inhibited by the cheese production parameters that, in turn, depend on the cheese dimension. Generally, temperature and pH exerted the more relevant effects on the enzymatic activities, and in many cases, a relevant interactive effect of these variables was observed. Increasing salt concentration slowed down broad-specificity amino-peptidase C, glutamyl aminopeptidase A, proline iminopeptidase, and peptidase with high specificity for leucine and alanine. Interestingly, this variable did not affect broad-specificity aminopeptidase N and positively affected X-prolyl dipeptidyl aminopeptidase. The models elaborated varying pH, temperatures, and salt concentration and were a useful, low cost, and fast tool to understand the role of the main peptidases in the different phases of cheese ripening in relation to the major environmental factors influencing enzyme activity.

Impact of marital status during diagnosis on cancer-caused specific survival in acute myeloid leukemia patients: a case-control and population-based study

PubMed Central

Zheng, Zhuojun; Zhu, Yuandong; Li, Xiaodong; Hu, Wenwei; Jiang, Jingting

2017-01-01

Objective This study investigated the impact of marital status on cancer-caused specific mortality among acute myeloid leukemia (AML) patients in the United States. Methods We used the Surveillance, Epidemiology and End Results program to identify 50,825 patients who had their clinical and follow-up information available and were diagnosed for AML between the years 1988 and 2015. The univariate and multivariable Cox regression models were used to analyze the patient data, and to minimize the group differences due to covariates between groups, a 1:1 propensity score matching was used in subsequent subgroup analysis. Results Our study demonstrated that married patients were less likely to die due to AML after adjusting for demographic and clinicopathological variables, than patients with variable unmarried status. Further analysis indicated that widowed, divorced and never married status correlated with poor cancer-cause specific survival than being married in almost all subgroups after being adjusted for the aforementioned variables (P<0.05). However, the difference between married and separated was not apparent. Moreover, similar survival analysis results were also observed in the 1:1 matched subgroups of marital status, but they displayed varied prognostic factors between them. The association of survival benefit with marriage in AML was consistent with the published survival benefit of conventional therapeutic approaches. Conclusion Overall, our study concluded that unmarried AML patients were at greater risk of cancer-specific mortality than married, and thus indicated that physicians should focus on health care strategies that target social support, in order to reduce the cancer-specific mortality in unmarried patients. PMID:28977979