431 kA/cm2 peak tunneling current density in GaN/AlN resonant tunneling diodes

NASA Astrophysics Data System (ADS)

Growden, Tyler A.; Zhang, Weidong; Brown, Elliott R.; Storm, David F.; Hansen, Katurah; Fakhimi, Parastou; Meyer, David J.; Berger, Paul R.

2018-01-01

We report on the design and fabrication of high current density GaN/AlN double barrier resonant tunneling diodes grown via plasma assisted molecular-beam epitaxy on bulk GaN substrates. A quantum-transport solver was used to model and optimize designs with high levels of doping and ultra-thin AlN barriers. The devices displayed repeatable room temperature negative differential resistance with peak-to-valley current ratios ranging from 1.20 to 1.60. A maximum peak tunneling current density (Jp) of 431 kA/cm2 was observed. Cross-gap near-UV (370-385 nm) electroluminescence (EL) was observed above +6 V when holes, generated from a polarization induced Zener tunneling effect, recombine with electrons in the emitter region. Analysis of temperature dependent measurements, thermal resistance, and the measured EL spectra revealed the presence of severe self-heating effects.

50 MHz-10 GHz low-power resistive feedback current-reuse mixer with inductive peaking for cognitive radio receiver.

PubMed

Vitee, Nandini; Ramiah, Harikrishnan; Chong, Wei-Keat; Tan, Gim-Heng; Kanesan, Jeevan; Reza, Ahmed Wasif

2014-01-01

A low-power wideband mixer is designed and implemented in 0.13 µm standard CMOS technology based on resistive feedback current-reuse (RFCR) configuration for the application of cognitive radio receiver. The proposed RFCR architecture incorporates an inductive peaking technique to compensate for gain roll-off at high frequency while enhancing the bandwidth. A complementary current-reuse technique is used between transconductance and IF stages to boost the conversion gain without additional power consumption by reusing the DC bias current of the LO stage. This downconversion double-balanced mixer exhibits a high and flat conversion gain (CG) of 14.9 ± 1.4 dB and a noise figure (NF) better than 12.8 dB. The maximum input 1-dB compression point (P1dB) and maximum input third-order intercept point (IIP3) are -13.6 dBm and -4.5 dBm, respectively, over the desired frequency ranging from 50 MHz to 10 GHz. The proposed circuit operates down to a supply headroom of 1 V with a low-power consumption of 3.5 mW.

F2 layer characteristics and electrojet strength over an equatorial station

NASA Astrophysics Data System (ADS)

Adebesin, B. O.; Adeniyi, J. O.; Adimula, I. A.; Reinisch, B. W.; Yumoto, K.

2013-09-01

The data presented in this work describes the diurnal and seasonal variation in hmF2, NmF2, and the electrojet current strength over an African equatorial station during a period of low solar activity. The F2 region horizontal magnetic element H revealed that the Solar quiet Sq(H) daily variation rises from early morning period to maximum around local noon and falls to lower values towards evening. The F2 ionospheric current responsible for the magnetic field variations is inferred to build up at the early morning hours, attaining maximum strength around 1200 LT. The Sq variation across the entire months was higher during the daytime than nighttime. This is ascribed to the variability of the ionospheric parameters like conductivity and winds structure in this region. Seasonal daytime electrojet (EEJ) current strength for June solstice, March and September equinoxes, respectively had peak values ranging within 27-35 nT (at 1400 LT) , 30-40 nT (at 1200 LT) and 35-45 nT (at 1500 LT). The different peak periods of the EEJ strength were attributed to the combined effects of the peak electron density and electric field. Lastly, the EEJ strength was observed to be higher during the equinoxes than the solstice period.

The safe use of automated external defibrillators in a wet environment.

PubMed

Lyster, Tom; Jorgenson, Dawn; Morgan, Carl

2003-01-01

There has been concern regarding potential shock hazards for rescuers or bystanders when a defibrillator is used in a wet environment and the recommended safety procedure, moving the patient to a dry area, is not followed. To measure the electrical potentials associated with the use of an automated external defibrillator (AED) in a realistically modeled wet environment. A raw processed turkey was used as a patient surrogate. The turkey was placed on a cement floor while pool water was applied to the surrounding area. To simulate a rescuer or bystander in the vicinity of a patient, a custom sense probe was constructed. Defibrillation shocks were delivered to the turkey and the probe was used to measure the voltage an operator/bystander would receive at different points surrounding the surrogate. The test was repeated with salt water. The maximum voltage occurred approximately 15 cm from the simulated patient and measured 14 V peak (current 14 mA peak) in the case of pool water, and 30 V peak (current 30 mA peak) in the case of salt water. Thirty volts may result in some minor sensation by the operator or bystander, but is considered unlikely to be hazardous under these circumstances. The maximum currents were lower than allowed by safety standards. Although defibrillation in a wet environment is not recommended practice, our simulation of a patient and a rescuer/bystander in a wet environment did not show significant risk should circumstances demand it.

Review of Seismic Hazard Issues Associated with Auburn Dam Project, Sierra Nevada Foothills, California

USGS Publications Warehouse

Schwartz, D.P.; Joyner, W.B.; Stein, R.S.; Brown, R.D.; McGarr, A.F.; Hickman, S.H.; Bakun, W.H.

1996-01-01

Summary -- The U.S. Geological Survey was requested by the U.S. Department of the Interior to review the design values and the issue of reservoir-induced seismicity for a concrete gravity dam near the site of the previously-proposed Auburn Dam in the western foothills of the Sierra Nevada, central California. The dam is being planned as a flood-control-only dam with the possibility of conversion to a permanent water-storage facility. As a basis for planning studies the U.S. Army Corps of Engineers is using the same design values approved by the Secretary of the Interior in 1979 for the original Auburn Dam. These values were a maximum displacement of 9 inches on a fault intersecting the dam foundation, a maximum earthquake at the site of magnitude 6.5, a peak horizontal acceleration of 0.64 g, and a peak vertical acceleration of 0.39 g. In light of geological and seismological investigations conducted in the western Sierran foothills since 1979 and advances in the understanding of how earthquakes are caused and how faults behave, we have developed the following conclusions and recommendations: Maximum Displacement. Neither the pre-1979 nor the recent observations of faults in the Sierran foothills precisely define the maximum displacement per event on a fault intersecting the dam foundation. Available field data and our current understanding of surface faulting indicate a range of values for the maximum displacement. This may require the consideration of a design value larger than 9 inches. We recommend reevaluation of the design displacement using current seismic hazard methods that incorporate uncertainty into the estimate of this design value. Maximum Earthquake Magnitude. There are no data to indicate that a significant change is necessary in the use of an M 6.5 maximum earthquake to estimate design ground motions at the dam site. However, there is a basis for estimating a range of maximum magnitudes using recent field information and new statistical fault relations. We recommend reevaluating the maximum earthquake magnitude using current seismic hazard methodology. Design Ground Motions. A large number of strong-motion records have been acquired and significant advances in understanding of ground motion have been achieved since the original evaluations. The design value for peak horizontal acceleration (0.64 g) is larger than the median of one recent study and smaller than the median value of another. The value for peak vertical acceleration (0.39 g) is somewhat smaller than median values of two recent studies. We recommend a reevaluation of the design ground motions that takes into account new ground motion data with particular attention to rock sites at small source distances. Reservoir-Induced Seismicity. The potential for reservoir-induced seismicity must be considered for the Auburn Darn project. A reservoir-induced earthquake is not expected to be larger than the maximum naturally occurring earthquake. However, the probability of an earthquake may be enhanced by reservoir impoundment. A flood-control-only project may involve a lower probability of significant induced seismicity than a multipurpose water-storage dam. There is a need to better understand and quantify the likelihood of this hazard. A methodology should be developed to quantify the potential for reservoir induced seismicity using seismicity data from the Sierran foothills, new worldwide observations of induced and triggered seismicity, and current understanding of the earthquake process. Reevaluation of Design Parameters. The reevaluation of the maximum displacement, maximum magnitude earthquake, and design ground motions can be made using available field observations from the Sierran foothills, updated statistical relations for faulting and ground motions, and current computational seismic hazard methodologies that incorporate uncertainty into the analysis. The reevaluation does not require significant new geological field studies.

PIC simulation of the vacuum power flow for a 5 terawatt, 5 MV, 1 MA pulsed power system

NASA Astrophysics Data System (ADS)

Liu, Laqun; Zou, Wenkang; Liu, Dagang; Guo, Fan; Wang, Huihui; Chen, Lin

2018-03-01

In this paper, a 5 Terawatt, 5 MV, 1 MA pulsed power system based on vacuum magnetic insulation is simulated by the particle-in-cell (PIC) simulation method. The system consists of 50 100-kV linear transformer drive (LTD) cavities in series, using magnetically insulated induction voltage adder (MIVA) technology for pulsed power addition and transmission. The pulsed power formation and the vacuum power flow are simulated when the system works in self-limited flow and load-limited flow. When the pulsed power system isn't connected to the load, the downstream magnetically insulated transmission line (MITL) works in the self-limited flow, the maximum of output current is 1.14 MA and the amplitude of voltage is 4.63 MV. The ratio of the electron current to the total current is 67.5%, when the output current reached the peak value. When the impedance of the load is 3.0 Ω, the downstream MITL works in the self-limited flow, the maximums of output current and the amplitude of voltage are 1.28 MA and 3.96 MV, and the ratio of the electron current to the total current is 11.7% when the output current reached the peak value. In addition, when the switches are triggered in synchronism with the passage of the pulse power flow, it effectively reduces the rise time of the pulse current.

30 CFR 817.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2014 CFR

2014-07-01

... either the maximum peak-particle-velocity limits of paragraph (d)(2), the scaled-distance equation of... authority before the initiation of blasting. (2) Maximum peak-particle velocity. (i) The maximum ground... site, in feet Maximum allowable peak particle velocity (V max) for ground vibration, in inches/second 1...

30 CFR 817.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2013 CFR

2013-07-01

... either the maximum peak-particle-velocity limits of paragraph (d)(2), the scaled-distance equation of... authority before the initiation of blasting. (2) Maximum peak-particle velocity. (i) The maximum ground... site, in feet Maximum allowable peak particle velocity (V max) for ground vibration, in inches/second 1...

30 CFR 817.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2012 CFR

2012-07-01

... either the maximum peak-particle-velocity limits of paragraph (d)(2), the scaled-distance equation of... authority before the initiation of blasting. (2) Maximum peak-particle velocity. (i) The maximum ground... site, in feet Maximum allowable peak particle velocity (V max) for ground vibration, in inches/second 1...

30 CFR 817.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2010 CFR

2010-07-01

... either the maximum peak-particle-velocity limits of paragraph (d)(2), the scaled-distance equation of... authority before the initiation of blasting. (2) Maximum peak-particle velocity. (i) The maximum ground... site, in feet Maximum allowable peak particle velocity (V max) for ground vibration, in inches/second 1...

30 CFR 817.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2011 CFR

2011-07-01

... either the maximum peak-particle-velocity limits of paragraph (d)(2), the scaled-distance equation of... authority before the initiation of blasting. (2) Maximum peak-particle velocity. (i) The maximum ground... site, in feet Maximum allowable peak particle velocity (V max) for ground vibration, in inches/second 1...

Assessment of the magnetic field exposure due to the battery current of digital mobile phones.

PubMed

Jokela, Kari; Puranen, Lauri; Sihvonen, Ari-Pekka

2004-01-01

Hand-held digital mobile phones generate pulsed magnetic fields associated with the battery current. The peak value and the waveform of the battery current were measured for seven different models of digital mobile phones, and the results were applied to compute approximately the magnetic flux density and induced currents in the phone-user's head. A simple circular loop model was used for the magnetic field source and a homogeneous sphere consisting of average brain tissue equivalent material simulated the head. The broadband magnetic flux density and the maximal induced current density were compared with the guidelines of ICNIRP using two various approaches. In the first approach the relative exposure was determined separately at each frequency and the exposure ratios were summed to obtain the total exposure (multiple-frequency rule). In the second approach the waveform was weighted in the time domain with a simple low-pass RC filter and the peak value was divided by a peak limit, both derived from the guidelines (weighted peak approach). With the maximum transmitting power (2 W) the measured peak current varied from 1 to 2.7 A. The ICNIRP exposure ratio based on the current density varied from 0.04 to 0.14 for the weighted peak approach and from 0.08 to 0.27 for the multiple-frequency rule. The latter values are considerably greater than the corresponding exposure ratios 0.005 (min) to 0.013 (max) obtained by applying the evaluation based on frequency components presented by the new IEEE standard. Hence, the exposure does not seem to exceed the guidelines. The computed peak magnetic flux density exceeded substantially the derived peak reference level of ICNIRP, but it should be noted that in a near-field exposure the external field strengths are not valid indicators of exposure. Currently, no biological data exist to give a reason for concern about the health effects of magnetic field pulses from mobile phones.

Transport of ion beam in an annular magnetically expanding helicon double layer thruster

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

Zhang, Yunchao, E-mail: yunchao.zhang@anu.edu.au; Charles, Christine; Boswell, Rod

2014-06-15

An ion beam generated by an annular double layer has been measured in a helicon thruster, which sustains a magnetised low-pressure (5.0 × 10{sup −4} Torr) argon plasma at a constant radio-frequency (13.56 MHz) power of 300 W. After the ion beam exits the annular structure, it merges into a solid centrally peaked structure in the diffusion chamber. As the annular ion beam moves towards the inner region in the diffusion chamber, a reversed-cone plasma wake (with a half opening angle of about 30°) is formed. This process is verified by measuring both the radial and axial distributions of the beam potential and beammore » current. The beam potential changes from a two-peak radial profile (maximum value ∼ 30 V, minimum value ∼ 22.5 V) to a flat (∼28 V) along the axial direction; similarly, the beam current changes from a two-peak to one-peak radial profile and the maximum value decreases by half. The inward cross-magnetic-field motion of the beam ions is caused by a divergent electric field in the source. Cross-field diffusion of electrons is also observed in the inner plume and is determined as being of non-ambipolar origin.« less

Strategy for the elucidation of elemental compositions of trace analytes based on a mass resolution of 100,000 full width at half maximum.

PubMed

Kaufmann, Anton

2010-07-30

Elemental compositions (ECs) can be elucidated by evaluating the high-resolution mass spectra of unknown or suspected unfragmented analyte ions. Classical approaches utilize the exact mass of the monoisotopic peak (M + 0) and the relative abundance of isotope peaks (M + 1 and M + 2). The availability of high-resolution instruments like the Orbitrap currently permits mass resolutions up to 100,000 full width at half maximum. This not only allows the determination of relative isotopic abundances (RIAs), but also the extraction of other diagnostic information from the spectra, such as fully resolved signals originating from (34)S isotopes and fully or partially resolved signals related to (15)N isotopes (isotopic fine structure). Fully and partially resolved peaks can be evaluated by visual inspection of the measured peak profiles. This approach is shown to be capable of correctly discarding many of the EC candidates which were proposed by commercial EC calculating algorithms. Using this intuitive strategy significantly extends the upper mass range for the successful elucidation of ECs. Copyright 2010 John Wiley & Sons, Ltd.

Indirectly pumped 3.7 THz InGaAs/InAlAs quantum-cascade lasers grown by metal-organic vapor-phase epitaxy.

PubMed

Fujita, Kazuue; Yamanishi, Masamichi; Furuta, Shinichi; Tanaka, Kazunori; Edamura, Tadataka; Kubis, Tillmann; Klimeck, Gerhard

2012-08-27

Device-performances of 3.7 THz indirect-pumping quantum-cascade lasers are demonstrated in an InGaAs/InAlAs material system grown by metal-organic vapor-phase epitaxy. The lasers show a low threshold-current-density of ~420 A/cm2 and a peak output power of ~8 mW at 7 K, no sign of parasitic currents with recourse to well-designed coupled-well injectors in the indirect pump scheme, and a maximum operating temperature of Tmax ~100 K. The observed roll-over of output intensities in current ranges below maximum currents and limitation of Tmax are discussed with a model for electron-gas heating in injectors. Possible ways toward elevation of Tmax are suggested.

NEUTRON SOURCE USING MAGNETIC COMPRESSION OF PLASMA

DOEpatents

Quinn, W.E.; Elmore, W.C.; Little, E.M.; Boyer, K.; Tuck, J.L.

1961-10-31

A fusion reactor is described that utilizes compression and heating of an ionized thermonuclear fuel by an externally applied magnetic field, thus avoiding reliance on the pinch effect and its associated instability problems. The device consists of a gas-confining ceramic container surrounded by a single circumferential coil having a shape such as to produce a magnetic mirror geometry. A sinusoidally-oscillating, exponentially-damped current is passed circumferentially around the container, through the coil, inducing a circumferential current in the gas. Maximum compression and plasma temperature are obtained at the peak of the current oscillations, coinciding with maximum magnetic field intensity. Enhanced temperatures are obtained in the second and succeeding half cycles because the thermal energy accumulates from one half cycle to the next. (AEC)

Maximizing ion current rectification in a bipolar conical nanopore fluidic diode using optimum junction location.

PubMed

Singh, Kunwar Pal

2016-10-12

The ion current rectification has been obtained as a function of the location of a heterojunction in a bipolar conical nanopore fluidic diode for different parameters to determine the junction location for maximum ion current rectification using numerical simulations. Forward current peaks for a specific location of the junction and reverse current decreases with the junction location due to a change in ion enrichment/depletion in the pore. The optimum location of the heterojunction shifts towards the tip with base/tip diameter and surface charge density, and towards the base with the electrolyte concentration. The optimum location of the heterojunction has been approximated by an equation as a function of pore length, base/tip diameter, surface charge density and electrolyte concentration. The study is useful to design a rectifier with maximum ion current rectification for practical purposes.

30 CFR 816.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2013 CFR

2013-07-01

... established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2), the... in the blasting plan and approved by the regulatory authority. (2) Maximum peak particle velocity. (i... (D), from the blasting site, in feet Maximum allowable peak particle velocity (V max) for ground...

30 CFR 816.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2014 CFR

2014-07-01

... established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2), the... in the blasting plan and approved by the regulatory authority. (2) Maximum peak particle velocity. (i... (D), from the blasting site, in feet Maximum allowable peak particle velocity (V max) for ground...

30 CFR 816.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2010 CFR

2010-07-01

... established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2), the... in the blasting plan and approved by the regulatory authority. (2) Maximum peak particle velocity. (i... (D), from the blasting site, in feet Maximum allowable peak particle velocity (V max) for ground...

30 CFR 816.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2012 CFR

2012-07-01

... established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2), the... in the blasting plan and approved by the regulatory authority. (2) Maximum peak particle velocity. (i... (D), from the blasting site, in feet Maximum allowable peak particle velocity (V max) for ground...

30 CFR 816.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2011 CFR

2011-07-01

... established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2), the... in the blasting plan and approved by the regulatory authority. (2) Maximum peak particle velocity. (i... (D), from the blasting site, in feet Maximum allowable peak particle velocity (V max) for ground...

A simple sub-nanosecond ultraviolet light pulse generator with high repetition rate and peak power.

PubMed

Binh, P H; Trong, V D; Renucci, P; Marie, X

2013-08-01

We present a simple ultraviolet sub-nanosecond pulse generator using commercial ultraviolet light-emitting diodes with peak emission wavelengths of 290 nm, 318 nm, 338 nm, and 405 nm. The generator is based on step recovery diode, short-circuited transmission line, and current-shaping circuit. The narrowest pulses achieved have 630 ps full width at half maximum at repetition rate of 80 MHz. Optical pulse power in the range of several hundreds of microwatts depends on the applied bias voltage. The bias voltage dependences of the output optical pulse width and peak power are analysed and discussed. Compared to commercial UV sub-nanosecond generators, the proposed generator can produce much higher pulse repetition rate and peak power.

Delay of cognitive gamma responses in Alzheimer's disease

PubMed Central

Başar, Erol; Emek-Savaş, Derya Durusu; Güntekin, Bahar; Yener, Görsev G.

2016-01-01

Event-related oscillations (EROs) reflect cognitive brain dynamics, while sensory-evoked oscillations (SEOs) reflect sensory activities. Previous reports from our lab have shown that those with Alzheimer's disease (AD) or mild cognitive impairment (MCI) have decreased activity and/or coherence in delta, theta, alpha and beta cognitive responses. In the current study, we investigated gamma responses in visual SEO and ERO in 15 patients with AD and in 15 age-, gender- and education-matched healthy controls. The following parameters were analyzed over the parietal-occipital regions in both groups: (i) latency of the maximum gamma response over a 0–800 ms time window; (ii) the maximum peak-to-peak amplitudes for each participant's averaged SEO and ERO gamma responses in 3 frequency ranges (25–30, 30–35, 40–48 Hz); and (iii) the maximum peak-to-peak amplitudes for each participant's averaged SEO and ERO gamma responses over a 0–800 ms time block containing four divided time windows (0–200, 200–400, 400–600, and 600–800 ms). There were main group effects in terms of both latency and peak-to-peak amplitudes of gamma ERO. However, peak-to-peak gamma ERO amplitude differences became noticeable only when the time block was divided into four time windows. SEO amplitudes in the 25–30 Hz frequency range of the 0–200 ms time window over the left hemisphere were greater in the healthy controls than in those with AD. Gamma target ERO latency was delayed up to 138 ms in AD patients when compared to healthy controls. This finding may be an effect of lagged neural signaling in cognitive circuits, which is reflected by the delayed gamma responses in those with AD. Based on the results of this study, we propose that gamma responses should be examined in a more detailed fashion using multiple frequency and time windows. PMID:26937378

Experimental Investigations on Combustion Behaviors of Live PVC Cables

NASA Astrophysics Data System (ADS)

Wang, Liufang; Zhang, Jiaqing; Zhang, Bosi; Liu, Min; Fan, Minghao; Li, Qiang

2018-03-01

This paper investigated the combustion behaviors of live PVC cables with overload currents experimentally. The smoke coefficient of released smoke and the released gas concentration were examined. The results indicate that the combustion of live PVC cables can be divided into four stages, i.e., core exposed with a little smoke, obvious flame, maximum smoke and smoke depress. For most cases, using blue laser is better than using rad laser, since the extinction coefficient of the rad laser was larger than that of the blue laser. The response time of the detection of the released typical gases due to cable pyrolysis decreased and the peak values of the typical gases increased with the overload currents. In addition, the time to reach the peak value of gas concentration also decreased with the overload currents.

Walking performance in people with diabetic neuropathy: benefits and threats.

PubMed

Kanade, R V; van Deursen, R W M; Harding, K; Price, P

2006-08-01

Walking is recommended as an adjunct therapy to diet and medication in diabetic patients, with the aim of improving physical fitness, glycaemic control and body weight reduction. Therefore we evaluated walking activity on the basis of capacity, performance and potential risk of plantar injury in the diabetic population before it can be prescribed safely. Twenty-three subjects with diabetic neuropathy (DMPN) were compared with 23 patients with current diabetic foot ulcers, 16 patients with partial foot amputations and 22 patients with trans-tibial amputations. The capacity for walking was measured using a total heart beat index (THBI). Gait velocity and average daily strides were measured to assess the performance of walking, and its impact on weight-bearing was studied using maximum peak pressure. THBI increased (p<0.01) and gait velocity and daily stride count fell (p<0.001 for both) with progression of foot complications. The maximum peak pressures over the affected foot of patients with diabetic foot ulcers (p<0.05) and partial foot amputations (p<0.01) were higher than in the group with DMPN. On the contralateral side, the diabetic foot ulcer group showed higher maximum peak pressure over the total foot (p<0.05), and patients with partial foot amputations (p<0.01) and trans-tibial amputations (p<0.05) showed higher maximum peak pressure over the heel. Walking capacity and performance decrease with progression of foot complications. Although walking is recommended to improve fitness, it cannot be prescribed in isolation, considering the increased risk of plantar injury. For essential walking we therefore recommend the use of protective footwear. Walking exercise should be supplemented by partial or non-weight-bearing exercises to improve physical fitness in diabetic populations.

A low noise and high precision linear power supply with thermal foldback protection.

PubMed

Carniti, P; Cassina, L; Gotti, C; Maino, M; Pessina, G

2016-05-01

A low noise and high precision linear power supply was designed for use in rare event search experiments with macrobolometers. The circuit accepts at the input a "noisy" dual supply voltage up to ±15 V and gives at the output precise, low noise, and stable voltages that can be set between ±3.75 V and ±12.5 V in eight 1.25 V steps. Particular care in circuit design, component selection, and proper filtering results in a noise spectral density of 50nV/Hz at 1 Hz and 20nV/Hz white when the output is set to ±5 V. This corresponds to 125 nV RMS (0.8 μV peak to peak) between 0.1 Hz and 10 Hz, and 240 nV RMS (1.6 μV peak to peak) between 0.1 Hz and 100 Hz. The power supply rejection ratio (PSRR) of the circuit is 100 dB at low frequency, and larger than 40 dB up to high frequency, thanks to a proper compensation design. Calibration allows to reach a precision in the absolute value of the output voltage of ±70 ppm, or ±350 μV at ±5 V, and to reduce thermal drifts below ±1 ppm/(∘)C in the expected operating range. The maximum peak output current is about 6 A from each output. An original foldback protection scheme was developed that dynamically limits the maximum output current to keep the temperature of the output transistors within their safe operating range. An add-on card based on an ARM Cortex-M3 microcontroller is devoted to the monitoring and control of all circuit functionalities and provides remote communication via CAN bus.

Plasma bullet current measurements in a free-stream helium capillary jet

NASA Astrophysics Data System (ADS)

Oh, Jun-Seok; Walsh, James L.; Bradley, James W.

2012-06-01

A commercial current monitor has been used to measure the current associated with plasma bullets created in both the positive and negative half cycles of the sinusoidal driving voltage sustaining a plasma jet. The maximum values of the positive bullet current are typically ˜750 µA and persist for 10 µs, while the peaks in the negative current of several hundred μA are broad, persisting for about 40 µs. From the time delay of the current peaks with increasing distance from the jet nozzle, an average bullet propagation speed has been measured; the positive and negative bullets travel at 17.5 km s-1 and 3.9 km s-1 respectively. The net space charge associated with the bullet(s) has also been calculated; the positive and negative bullets contain a similar net charge of the order of 10-9 C measured at all monitor positions, with estimated charged particle densities nb of ˜1010-1011 cm-3 in the bullet.

Radial tunnel diodes based on InP/InGaAs core-shell nanowires

NASA Astrophysics Data System (ADS)

Tizno, Ofogh; Ganjipour, Bahram; Heurlin, Magnus; Thelander, Claes; Borgström, Magnus T.; Samuelson, Lars

2017-03-01

We report on the fabrication and characterization of radial tunnel diodes based on InP(n+)/InGaAs(p+) core-shell nanowires, where the effect of Zn-dopant precursor flow on the electrical properties of the devices is evaluated. Selective and local etching of the InGaAs shell is employed to access the nanowire core in the contact process. Devices with an n+-p doping profile show normal diode rectification, whereas n+-p+ junctions exhibit typical tunnel diode characteristics with peak-to-valley current ratios up to 14 at room temperature and 100 at 4.2 K. A maximum peak current density of 28 A/cm2 and a reverse current density of 7.3 kA/cm2 at VSD = -0.5 V are extracted at room temperature after normalization with the effective junction area.

ZT Optimization: An Application Focus

PubMed Central

Tuley, Richard; Simpson, Kevin

2017-01-01

Significant research has been performed on the challenge of improving thermoelectric materials, with maximum peak figure of merit, ZT, the most common target. We use an approximate thermoelectric material model, matched to real materials, to demonstrate that when an application is known, average ZT is a significantly better optimization target. We quantify this difference with some examples, with one scenario showing that changing the doping to increase peak ZT by 19% can lead to a performance drop of 16%. The importance of average ZT means that the temperature at which the ZT peak occurs should be given similar weight to the value of the peak. An ideal material for an application operates across the maximum peak ZT, otherwise maximum performance occurs when the peak value is reduced in order to improve the peak position. PMID:28772668

Early detection of Candida albicans biofilms at porous electrodes.

PubMed

Congdon, Robert B; Feldberg, Alexander S; Ben-Yakar, Natalie; McGee, Dennis; Ober, Christopher; Sammakia, Bahgat; Sadik, Omowunmi A

2013-02-15

We describe the development of an electrochemical sensor for early detection of biofilm using Candida albicans. The electrochemical sensor used the ability of biofilms to accept electrons from redox mediators relative to the number of metabolically active cells present. Cyclic voltammetry and differential pulse voltammetry techniques were used to monitor the redox reaction of K(3)Fe(CN)(6) at porous reticulated vitreous carbon (RVC) (238.7 cm(2)) working electrodes versus Ag/AgCl reference. A shift in the peak potential occurred after 12 h of film growth, which is attributed to the presence of C. albicans. Moreover, the intensity of the ferricyanide reduction peak first increased as C. albicans deposited onto the porous electrodes at various growth times. The peak current subsequently decreased at extended periods of growth of 48 h. The reduction in peak current was attributed to the biofilm reaching its maximum growth thickness, which correlated with the maximum number of metabolically active cells. The observed diffusion coefficients for the bare RVC and biofilm-coated electrodes were 2.2 × 10(-3) and 7.0 × 10(-6) cm(2)/s, respectively. The increase in diffusivity from the bare electrode to the biofilm-coated electrode indicated some enhancement of electron transfer mediated by the biofilm to the porous electrode. Verification of the growth of biofilm was achieved using scanning electron microcopy and laser scanning confocal imaging microscopy. Validation with conventional plating techniques confirmed that the correlation (R(2) = 0.9392) could be achieved between the electrochemical sensors data and colony-forming units. Copyright © 2012 Elsevier Inc. All rights reserved.

Monitoring of Time-Dependent System Profiles by Multiplex Gas Chromatography with Maximum Entropy Demodulation

NASA Technical Reports Server (NTRS)

Becker, Joseph F.; Valentin, Jose

1996-01-01

The maximum entropy technique was successfully applied to the deconvolution of overlapped chromatographic peaks. An algorithm was written in which the chromatogram was represented as a vector of sample concentrations multiplied by a peak shape matrix. Simulation results demonstrated that there is a trade off between the detector noise and peak resolution in the sense that an increase of the noise level reduced the peak separation that could be recovered by the maximum entropy method. Real data originated from a sample storage column was also deconvoluted using maximum entropy. Deconvolution is useful in this type of system because the conservation of time dependent profiles depends on the band spreading processes in the chromatographic column, which might smooth out the finer details in the concentration profile. The method was also applied to the deconvolution of previously interpretted Pioneer Venus chromatograms. It was found in this case that the correct choice of peak shape function was critical to the sensitivity of maximum entropy in the reconstruction of these chromatograms.

Synthesis and electroluminescence characterization of a new aluminum complex, [8-hydroxyquinoline] bis [2, 2'bipyridine] aluminum Al(Bpy)2q

NASA Astrophysics Data System (ADS)

Rahul, Kumar; Ritu, Srivastava; Punita, Singh

2016-01-01

We have synthesized and characterized a new electroluminescent material, [8-hydroxyquinoline] bis [2,2'bipyridine] aluminum. A solution of this material Al(Bpy)2q in toluene showed absorption maxima at 380 nm, which was attributed to the moderate energy (π-π*) transitions of the aromatic rings. The photoluminescence spectrum of Al(Bpy)2q in the toluene solution showed a peak at 518 nm. This material shows thermal stability up to 300 °C. The structure of the device is ITO/F4-TCNQ (1 nm)/α-NPD (35 nm)/Al(Bpy)2q (35 nm)/ BCP (6 nm)/Alq3 (28 nm)/LiF (1 nm)/Al (150 nm). This device exhibited a luminescence peak at 515 nm (CIE coordinates, x = 0.32, y = 0.49). The maximum luminescence of the device was 214 cd/m2 at 21 V. The maximum current efficiency of OLED was 0.12 cd/A at 13 V and the maximum power efficiency was 0.03 lm/W at 10 V.

Observation and measurement of negative differential resistance on PtSi Schottky junctions on porous silicon.

PubMed

Banihashemian, Seyedeh Maryam; Hajghassem, Hassan; Erfanian, Alireza; Aliahmadi, Majidreza; Mohtashamifar, Mansor; Mosakazemi, Seyed Mohamadhosein

2010-01-01

Nanosize porous Si is made by two step controlled etching of Si. The first etching step is carried on the Si surface and the second is performed after deposition of 75 Å of platinum on the formed surface. A platinum silicide structure with a size of less than 25 nm is formed on the porous Si surface, as measured with an Atomic Forced Microscope (AFM). Differential resistance curve as a function of voltage in 77 K and 100 K shows a negative differential resistance and indicates the effect of quantum tunneling. In general form, the ratio of maximum to minimum tunneling current (PVR) and the number of peaks in I-V curves reduces by increasing the temperature. However, due to accumulation of carriers behind the potential barrier and superposition of several peaks, it is observed that the PVR increases at 100 K and the maximum PVR at 100 K is 189.6.

Two Ca current components of the receptor current in the electroreceptors of the marine catfish Plotosus.

PubMed

Sugawara, Y

1989-02-01

In the isolated sensory epithelium of the Plotosus electroreceptor, the receptor current has been dissected into inward Ca current, ICa, and superimposed outward transient of Ca-gated K current, IK(Ca). In control saline (170 mM/liter Na), with IK(Ca) abolished by K blockers, ICa declined in two successive exponential phases with voltage-dependent time constants. Double-pulse experiments revealed that the test ICa was partially depressed by prepulses, maximally near voltage levels for the control ICa maximum, which suggests current-dependent inactivation. In low Na saline (80 mM/liter), ICa declined in a single phase with time constants similar to those of the slower phase in control saline. The test ICa was then unaffected by prepulses. The implied presence of two Ca current components, the fast and slow ICa's, were further examined. In control saline, the PSP externally recorded from the afferent nerve showed a fast peak and a slow tonic phase. The double-pulse experiments revealed that IK(Ca) and the peak PSP were similarly depressed, i.e., secondarily to inactivation of the peak current. The steady inward current, however, was unaffected by prolonged prepulses that were stepped to 0 mV, the in situ DC level. Therefore, the fast ICa seems to initiate IK(Ca) and phasic release of transmitter, which serves for phasic receptor responses. The slow ICa may provide persistent active current, which has been shown to maintain tonic receptor operation.

Plasma-filled diode based on the coaxial gun

NASA Astrophysics Data System (ADS)

Zherlitsyn, A. A.; Kovalchuk, B. M.; Pedin, N. N.

2012-10-01

The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of ≥1 MeV at the current of ≈100 kA was obtained in the experiments with a plasma-filled diode. The energy of ≈5 kJ with the peak power of ≥100 GW dissipated in the diode.

Plasma-filled diode based on the coaxial gun.

PubMed

Zherlitsyn, A A; Kovalchuk, B M; Pedin, N N

2012-10-01

The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of ≥1 MeV at the current of ≈100 kA was obtained in the experiments with a plasma-filled diode. The energy of ≈5 kJ with the peak power of ≥100 GW dissipated in the diode.

Measured close lightning leader-step electric-field-derivative waveforms.

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

Jordan, Doug M.; Hill, Dustin; Biagi, Christopher J.

2010-12-01

We characterize the measured electric field-derivative (dE/dt) waveforms of lightning stepped-leader steps from three negative lightning flashes at distances of tens to hundreds of meters. Electromagnetic signatures of leader steps at such close distances have rarely been documented in previous literature. Individual leader-step three-dimensional locations are determined by a dE/dt TOA system. The leader-step field derivative is typically a bipolar pulse with a sharp initial half-cycle of the same polarity as that of the return stroke, followed by an opposite polarity overshoot that decays relatively slowly to background level. This overshoot increases in amplitude relative to the initial peak andmore » becomes dominant as range decreases. The initial peak is often preceded by a 'slow front,' similar to the slow front that precedes the fast transition to peak in first return stroke dE/dt and E waveforms. The overall step-field waveform duration is typically less than 1 {micro}s. The mean initial peak of dE/dt, range-normalized to 100 km, is 7.4 V m{sup -1} {micro}s{sup -1} (standard deviation (S.D.), 3.7 V m{sup -1} {micro}s{sup -1}, N = 103), the mean half-peak width is 33.5 ns (S.D., 11.9 ns, N = 69), and the mean 10-to-90% risetime is 43.6 ns (S.D., 24.2 ns, N = 69). From modeling, we determine the properties of the leader step currents which produced two typical measured field derivatives, and we use one of these currents to calculate predicted leader step E and dE/dt as a function of source range and height, the results being in good agreement with our observations. The two modeled current waveforms had maximum rates of current rise-to-peak near 100 kA {micro}s{sup -1}, peak currents in the 5-7 kA range, current half-peak widths of about 300 ns, and charge transfers of {approx}3 mC. As part of the modeling, those currents were propagated upward at 1.5 x 10{sup 8} m s{sup -1}, with their amplitudes decaying exponentially with a decay height constant of 25 m.« less

Magnitude and frequency of floods in Nebraska

USGS Publications Warehouse

Beckman, Emil W.

1976-01-01

Observed maximum flood peaks at 303 gaging stations with 13 or more years of record and significant peaks at 57 short-term stations and 31 miscellaneous sites are useful in designing flood-control works for maximum safety from flood damage. Comparison is made with maximum observed floods in the United States.

Study of the second magnetization peak and the pinning behaviour in Ba(Fe0.935Co0.065)2As2 pnictide superconductor

NASA Astrophysics Data System (ADS)

Sundar, Shyam; Mosqueira, J.; Alvarenga, A. D.; Sóñora, D.; Sefat, A. S.; Salem-Sugui, S., Jr.

2017-12-01

Isothermal magnetic field dependence of magnetization and magnetic relaxation measurements were performed for the H\\parallel {{c}} axis on a single crystal of Ba(Fe0.935 Co0.065)2As2 pnictide superconductor having T c = 21.7 K. The second magnetization peak (SMP) for each isothermal M(H) was observed in a wide temperature range from T c to the lowest temperature of measurement (2 K). The magnetic field dependence of relaxation rate R(H), showed a peak (H spt) between H on (onset of SMP in M(H)) and H p (peak field of SMP in M(H)), which is likely to be related to a vortex-lattice structural phase transition, as suggested in the literature for a similar sample. In addition, the magnetic relaxation measured for magnetic fields near H spt showed some noise, which might be the signature of the structural phase transition of the vortex lattice. Analysis of the magnetic relaxation data using Maley’s criterion and the collective pinning theory suggested that the SMP in the sample was due to the collective (elastic) to plastic creep crossover, which was also accompanied by a rhombic to square vortex lattice phase transition. Analysis of the pinning force density suggested a single dominating pinning mechanism in the sample, which did not showing the usual δ {l} and δ {T}{{c}} nature of pinning. The critical current density (J c), estimated using the Bean critical state model, was found to be 5 × 105 A cm- 2 at 2 K in the zero magnetic field limit. Surprisingly, the maximum of the pinning force density was not responsible for the maximum value of the critical current density in the sample.

Generation of a pulsed low-energy electron beam using the channel spark device

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

Elgarhy, M. A. I., E-mail: elgarhy@azhar.edu.eg; Hassaballa, S. E.; Rashed, U. M.

2015-12-15

For the generation of low-energy electron beam, the design and characteristics of channel spark discharge (CSD) operating at a low voltage are presented in this paper. The discharge voltage, discharge current, X-ray emissions, and electron beam current were experimentally determined. The effects of the applied voltage, working gas pressure, and external capacitance on the CSD and beam parameters were measured. At an applied voltage of 11 kV, an oxygen gas pressure of 25 mTorr, and an external capacitance of 16.45 nF, the maximum measured current was 900 A. The discharge current increased with the increase in the pressure and capacitance,more » while its periodic time decreased with the increase in the pressure. Two types of the discharge were identified and recorded: the hollow cathode discharge and the conduction discharge. A Faraday cup was used to measure the beam current. The maximum measured beam current was 120 A, and the beam signal exhibited two peaks. The increase in both the external capacitance and the applied discharge voltage increased the maximum electron beam current. The electron-beam pulse time decreased with the increase in the gas pressure at a constant voltage and increased with the decrease in the applied discharge voltage. At an applied voltage of 11 kV and an oxygen gas pressure of 15 mTorr, the maximum beam energy was 2.8 keV. The X-ray signal intensity decreased with the increase in the gas pressure and increased with the increase in the capacitance.« less

Study on transport properties of silicene monolayer under external field using NEGF method

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

Syaputra, Marhamni, E-mail: marhamni@students.itb.ac.id; Wella, Sasfan Arman; Wungu, Triati Dewi Kencana

2015-09-30

We investigate the current-voltage (I-V) characteristics of a pristine monolayer silicene using non-equilibrium Green function (NEGF) method combining with density functional theory (DFT). This method succeeded in showing the relationship of I and V on silicene corresponding to the electronic characteristics such as density of states. The external field perpendicular to the silicene monolayer affects in increasing of the current. Under 0.2 eV external field, the current reaches the maximum peak at Vb = 0.3 eV with the increase is about 60% from what it is in zero external field.

Three years of lightning impulse charge moment change measurements in the United States

NASA Astrophysics Data System (ADS)

Cummer, Steven A.; Lyons, Walter A.; Stanley, Mark A.

2013-06-01

We report and analyze 3 years of lightning impulse charge moment change (iCMC) measurements obtained from an automated, real time lightning charge moment change network (CMCN). The CMCN combines U.S. National Lightning Detection Network (NLDN) lightning event geolocations with extremely low frequency (≲1 kHz) data from two stations to provide iCMC measurements across the entire United States. Almost 14 million lightning events were measured in the 3 year period. We present the statistical distributions of iCMC versus polarity and NLDN-measured peak current, including corrections for the detection efficiency of the CMCN versus peak current. We find a broad distribution of iCMC for a given peak current, implying that these parameters are at best only weakly correlated. Curiously, the mean iCMC does not monotonically increase with peak current, and in fact, drops for positive CG strokes above +150 kA. For all positive strokes, there is a boundary near 20 C km that separates seemingly distinct populations of high and low iCMC strokes. We also explore the geographic distribution of high iCMC lightning strokes. High iCMC positive strokes occur predominantly in the northern midwest portion of the U.S., with a secondary peak over the gulf stream region just off the U.S. east coast. High iCMC negative strokes are also clustered in the midwest, although somewhat south of most of the high iCMC positive strokes. This is a region far from the locations of maximum occurrence of high peak current negative strokes. Based on assumed iCMC thresholds for sprite production, we estimate that approximately 35,000 positive polarity and 350 negative polarity sprites occur per year over the U.S. land and near-coastal areas. Among other applications, this network is useful for the nowcasting of sprite-producing storms and storm regions.

Electron acceleration in downward auroral field-aligned currents

NASA Astrophysics Data System (ADS)

Cran-McGreehin, Alexandra P.; Wright, Andrew N.

2005-10-01

The auroral downward field-aligned current is mainly carried by electrons accelerated up from the ionosphere into the magnetosphere along magnetic field lines. Current densities are typically of the order of a few μ Am-2, and the associated electrons are accelerated to energies of several hundred eV up to a few keV. This downward current has been modeled by Temerin and Carlson (1998) using an electron fluid. This paper extends that model by describing the electron populations via distribution functions and modeling all of the F region. We assume a given ion density profile, and invoke quasi-neutrality to solve for the potential along the field line. Several important locations and quantities emerge from this model: the ionospheric trapping point, below which the ionospheric population is trapped by an ambipolar electric field; the location of maximum E∥, of the order of a few mVm-1, which lies earthward of the B/n peak; the acceleration region, located around the B/n peak, which normally extends between altitudes of 500 and 3000 km; and the total potential increase along the field line, of the order of a few hundred V up to several kV. The B/n peak is found to be the central factor determining the altitude and magnitude of the accelerating potential required. Indeed, the total potential drop is found to depend solely on the equilibrium properties in the immediate vicinity of the B/n peak.

Evaluation of the antibacterial activity of a cationic polymer in aqueous solution with a convenient electrochemical method.

PubMed

Wang, Yihong; Guo, Qing; Wang, Huafu; Qian, Kun; Tian, Liang; Yao, Chen; Song, Wei; Shu, Weixia; Chen, Ping; Qi, Jinxu

2017-02-01

Quaternized chitosan is a cationic biopolymer with good antibacterial activity, biocompatibility, and biodegradability, and it has been widely applied in many fields. We have developed a convenient method to evaluate the antibacterial activity of hydroxypropyltrimethylammonium chloride chitosan (HACC) with a nonionic surfactant poloxamer in aqueous solution by monitoring the change of the oxidation peak current in cyclic voltammetry. Increasing values of the oxidation peak current were positively correlated with the antibacterial activity of HACC-poloxamer solutions. Optical microscope images, the zeta potential, and fluorescence spectroscopy showed that the aggregation state of HACC-poloxamer was related to the ratio of the two polymers and also to the antibacterial activity and oxidation peak current. At an HACC-to-poloxamer ratio of 1:0.75, the maximum surface charge density and the smooth edge of HACC-poloxamer aggregates can accelerate diffusion in aqueous solution. It is expected that this convenient method can be applied for a quick evaluation of the antibacterial activity of cationic biopolymers in aqueous solution. Graphical Abstract The cyclic voltammograms of MB in HACC/poloxamer solution, and the antibacterial efficiency against S. aureus after incubated with HACC (a) and 1/0.75 of HACC/poloxamer (b).

Optimization of Surface Roughness Parameters of Al-6351 Alloy in EDC Process: A Taguchi Coupled Fuzzy Logic Approach

NASA Astrophysics Data System (ADS)

Kar, Siddhartha; Chakraborty, Sujoy; Dey, Vidyut; Ghosh, Subrata Kumar

2017-10-01

This paper investigates the application of Taguchi method with fuzzy logic for multi objective optimization of roughness parameters in electro discharge coating process of Al-6351 alloy with powder metallurgical compacted SiC/Cu tool. A Taguchi L16 orthogonal array was employed to investigate the roughness parameters by varying tool parameters like composition and compaction load and electro discharge machining parameters like pulse-on time and peak current. Crucial roughness parameters like Centre line average roughness, Average maximum height of the profile and Mean spacing of local peaks of the profile were measured on the coated specimen. The signal to noise ratios were fuzzified to optimize the roughness parameters through a single comprehensive output measure (COM). Best COM obtained with lower values of compaction load, pulse-on time and current and 30:70 (SiC:Cu) composition of tool. Analysis of variance is carried out and a significant COM model is observed with peak current yielding highest contribution followed by pulse-on time, compaction load and composition. The deposited layer is characterised by X-Ray Diffraction analysis which confirmed the presence of tool materials on the work piece surface.

New GaN based HEMT with Si3N4 or un-doped region in the barrier for high power applications

NASA Astrophysics Data System (ADS)

Razavi, S. M.; Tahmasb Pour, S.; Najari, P.

2018-06-01

New AlGaN/GaN high electron mobility transistors (HEMTs) that their barrier layers under the gate are divided into two regions horizontally are presented in this work. Upper region is Si3N4 (SI-HEMT) or un-doped AlGaN (UN-HEMT) and lower region is AlGaN with heavier doping compared to barrier layer. Upper region in SI-HEMT and UN-HEMT reduces peak electric field in the channel and then improves breakdown voltage considerably. Lower region increases electron density in the two dimensional electron gas (2-DEG) and enhances drain current significantly. For instance, saturated drain current in SI-HEMT is about 100% larger than that in the conventional one. Moreover, the maximum breakdown voltage in the proposed structures is 65 V. This value is about 30% larger than that in the conventional transistor (50 V). Also, suggested structure reduces short channel effect such as DIBL. The maximum gm is obtained in UN-HEMT and conventional devices. Proposed structures improve breakdown voltage and saturated drain current and then enhance maximum output power density. Maximum output power density in the new structures is about 150% higher than that in the conventional.

A comparison of cleat types during two football-specific tasks on FieldTurf.

PubMed

Queen, R M; Charnock, B L; Garrett, W E; Hardaker, W M; Sims, E L; Moorman, C T

2008-04-01

To examine the effect of different cleat plate configurations on plantar pressure during two tasks. Thirty-six athletes ran an agility course 5 times while wearing 4 different types of Nike Vitoria cleats: (1) bladed, (2) elliptical firm ground, (3) hard ground and (4) turf. Plantar pressure data were recorded during a side cut and a cross cut using Pedar-X insoles. Controlled laboratory study No history of lower extremity injury in the past 6 months, no previous foot or ankle surgery, not currently wearing foot orthotics and play a cleated sport at least twice a week. Total foot contact time, contact area, maximum force, peak pressure and the force-time integral (FTI) in the medial, middle and lateral regions of the forefoot were collected. A 1x4 ANOVA (alpha = 0.05) was performed on each dependent variable. A Bonferroni adjustment was conducted (alpha = 0.008). In the cross cut task, statistical differences between cleats were observed in three variables: total foot peak pressure, lateral forefoot FTI, and lateral forefoot normalised maximum force. In the side cut task, statistical differences between cleats were observed in 4 variables: total foot peak pressure, the medial and middle forefoot FTI, and the medial and middle forefoot normalised maximum force. Significant differences in forefoot loading patterns existed between cleat types. Based on the results of this study, it might be beneficial to increase the forefoot cushioning in cleats in an attempt to decrease loading in these regions of the foot.

The influence of synthetic hyetograph parameters on simulation results of runoff from urban catchment

NASA Astrophysics Data System (ADS)

Mazurkiewicz, Karolina; Skotnicki, Marcin

2018-02-01

The paper presents the results of analysis of the influence of the maximum intensity (peak) location in the synthetic hyetograph and rainfall duration on the maximum outflow from urban catchment. For the calculation Chicago hyetographs with a duration from 15 minutes to 180 minutes and peak location between 20% and 50% of the total rainfall duration were design. Runoff simulation was performed using the SWMM5 program for three models of urban catchment with area from 0.9 km2 to 6.7 km2. It was found that the increase in the rainfall peak location causes the increase in the maximum outflow up to 17%. For a given catchment the greatest maximum outflow is generated by the rainfall, which time to peak corresponds to the flow time through the catchment. Presented results may be useful for choosing the rainfall parameters for storm sewer systems modeling.

Influence of nitromethane concentration on ignition energy and explosion parameters in gaseous nitromethane/air mixtures.

PubMed

Zhang, Qi; Li, Wei; Lin, Da-Chao; He, Ning; Duan, Yun

2011-01-30

The aim of this paper is to provide new experimental data of the minimum ignition energy (MIE) of gaseous nitromethane/air mixtures to discuss the explosion pressure and the flame temperature as a function of nitromethane concentration. Observations on the influence of nitromethane concentration on combustion pressure and temperature through the pressure and temperature measure system show that peak temperature (the peak of combustion temperature wave) is always behind peak pressure (the peak of the combustion pressure wave) in arrival time, the peak combustion pressure of nitromethane increases in the range of its volume fraction 10-40% as the concentration of nitromethane increases, and it slightly decreases in the range of 40-50%. The maximum peak pressure is equal to 0.94 MPa and the minimum peak pressure 0.58 MPa. Somewhat similar to the peak pressure, the peak combustion temperature increases with the volume fraction of nitromethane in the range of 10-40%, and slightly decreases in 40-50%. The maximum peak temperature is 1340 °C and the minimum 860 °C. The combustion temperature rise rate increases with the concentration of nitromethane in 10-30%, while decreases in 30-50% and its maximum value of combustion temperature rise rate in 10-50% is 4200 °C/s at the volume fraction of 30%. Influence of the concentration of nitromethane on the combustion pressure rise rate is relatively complicated, and the maximum value of rise rate of combustion pressure wave in 10-50% is 11 MPa/s at the concentration 20%. Copyright © 2010 Elsevier B.V. All rights reserved.

Narrowband ultraviolet photodetector based on MgZnO and NPB heterojunction.

PubMed

Hu, Zuofu; Li, Zhenjun; Zhu, Lu; Liu, Fengjuan; Lv, Yanwu; Zhang, Xiqing; Wang, Yongsheng

2012-08-01

An ultraviolet photodetector was fabricated based on Mg0.07Zn0.93O heterojunction. N, N'-bis (naphthalen-1-y1)-N, N'-bis(pheny) benzidine was selected as the hole transporting layer. I-V characteristic curves of the device were measured in the dark and under the illumination of 340 nm UV light with density of 1.33 mW/cm2. The device showed a low dark current of about 3×10(-10) A and a high photo-dark current ratio of 1×10(5) at -2 V bias. A narrowband photoresponse was observed from 300 to 400 nm and centered at 340 nm with a full width at half-maximum of only 30 nm. The maximum peak response is at 340 nm, which is 0.192 A/W at the bias of -1 V.

Effects of Wildfire on the Hydrology of Capulin and Rito de los Frijoles canyons, Bandelier National Monument, New Mexico

USGS Publications Warehouse

Veenhuis, Jack E.

2002-01-01

In June of 1977, the La Mesa wildfire burned 15,270 acres in and around Frijoles Canyon in Bandelier National Monument and the adjacent Santa Fe National Forest, New Mexico. The Dome wildfire in April of 1996 in Bandelier National Monument burned 16,516 acres in Capulin Canyon and the surrounding Dome Wilderness area. Both watersheds are characterized by abundant and extensive archeological sites that could be affected by increased runoff and accelerated rates of erosion, which typically occur after a wildfire. The U.S. Geological Survey in cooperation with the National Park Service monitored the wildfires' effects on streamflow in both canyons. The magnitude of large stormflows increased dramatically after these wildfires; peak flows at the most downstream streamflow-gaging station in Frijoles and Capulin Canyons increased to about 160 times the maximum recorded flood prior to the fire. Maximum peak flow was 3,030 cubic feet per second at the gaging station in Frijoles Canyon (drainage area equals 18.1 square miles) and 3,630 cubic feet per second at the most downstream crest-stage gage in Capulin Canyon (drainage area equals 14.1 square miles). The pre-fire maximum peak flow recorded in these two canyons was 19 and an estimated 25 cubic feet per second, respectively. As vegetation reestablished itself during the second year, the post-fire annual maximum peak flow decreased to about 10 to 15 times the pre-fire annual maximum peak flow. During the third year, maximum annual peak flows decreased to about three to five times the pre-fire maximum peak flow. In the 22 years since the La Mesa wildfire, flood magnitudes have not completely returned to pre-fire size. Post-fire flood magnitudes in Frijoles and Capulin Canyons do not exceed the maximum floods per drainage area for physiographic regions 5 and 6 in New Mexico. For a burned watershed, however, the peak flows that occur after a wildfire are several orders of magnitude larger than normal forested watershed peak flows. The frequency of larger stormflows also increased in response to the effects of the wildfires in both canyons. In Frijoles Canyon, the number of peak stormflows greater than the pre-fire maximum flow of 19 cubic feet per second was 15 in 1977, 9 in 1978, and 5 in 1979, which is about the magnitude of the maximum pre-fire peak flow in both canyons. Again the hydrologic effects of a wildfire seem to be more pronounced for the 3 years following the date of the fire. Likewise, larger peakflows occurred more frequently in Capulin Canyon for the first 3 years after the 1996 wildfire. Median suspended-sediment concentrations in samples collected in Frijoles Canyon in 1977 were 1,330 milligrams per liter; median concentrations were 16 milligrams per liter after the watershed stabilized in 1993-95. The annual load calculated from regression equations for load compared to flow for the first year after the wildfire was 220 times the annual load for the post-recovery period. To convey the increased frequency and magnitude of average flows in Capulin Canyon after the 1996 Dome wildfire, the stream channel in Capulin Canyon increased in flow capacity by widening and downcutting. As Capulin Canyon peak flows have decreased in both magnitude and frequency with vegetative recovery, the stream channel also has slowly begun to readjust. The channel at the most downstream crest-stage gage, which has the shallowest initial valley slope, is showing the first signs of aggradation.

First-principles study on electron transport properties of carbon-silicon mixed chains

NASA Astrophysics Data System (ADS)

Hu, Wei; Zhou, Qinghua; Liang, Yan; Liu, Wenhua; Wang, Tao; Wan, Haiqing

2018-03-01

In this paper, the transport properties of carbon-silicon mixed chains are studied by using the first-principles. We studied five atomic chain models. In these studies, we found that the equilibrium conductances of atomic chains appear to oscillate, the maximum conductance and the minimum conductance are more than twice the difference. Their I-V curves are linear and show the behavior of metal resistance, M5 system and M2 system current ratio is the largest in 0.9 V, which is 3.3, showing a good molecular switch behavior. In the case of bias, while the bias voltage increases, the transmission peaks move from the Fermi level. The resonance transmission peak height is reduced near the Fermi level. In the higher energy range, a large resonance transmission peak reappears, there is still no energy cut-off range.

Contribution of ASDEX Upgrade to disruption studies for ITER

NASA Astrophysics Data System (ADS)

Pautasso, G.; Zhang, Y.; Reiter, B.; Giannone, L.; Gruber, O.; Herrmann, A.; Kardaun, O.; Khayrutdinov, K. K.; Lukash, V. E.; Maraschek, M.; Mlynek, A.; Nakamura, Y.; Schneider, W.; Sias, G.; Sugihara, M.; ASDEX Upgrade Team

2011-10-01

This paper describes the most recent contributions of ASDEX Upgrade to ITER in the field of disruption studies. (1) The ITER specifications for the halo current magnitude are based on data collected from several tokamaks and summarized in the plot of the toroidal peaking factor versus the maximum halo current fraction. Even if the maximum halo current in ASDEX Upgrade reaches 50% of the plasma current, the duration of this maximum lasts a fraction of a ms. (2) Long-lasting asymmetries of the halo current are rare and do not give rise to a large asymmetric component of the mechanical forces on the machine. Differently from JET, these asymmetries are neither locked nor exhibit a stationary harmonic structure. (3) Recent work on disruption prediction has concentrated on the search for a simple function of the most relevant plasma parameters, which is able to discriminate between the safe and pre-disruption phases of a discharge. For this purpose, the disruptions of the last four years have been classified into groups and then discriminant analysis is used to select the most significant variables and to derive the discriminant function. (4) The attainment of the critical density for the collisional suppression of the runaway electrons seems to be technically and physically possible on our medium size tokamak. The CO2 interferometer and the AXUV diagnostic provide information on the highly 3D impurity transport process during the whole plasma quench.

Post-fire, rainfall intensity-peak discharge relations for three mountainous watersheds in the Western USA

USGS Publications Warehouse

Moody, J.A.; Martin, D.A.

2001-01-01

Wildfire alters the hydrologic response of watersheds, including the peak discharges resulting from subsequent rainfall. Improving predictions of the magnitude of flooding that follows wildfire is needed because of the increase in human population at risk in the wildland-urban interface. Because this wildland-urban interface is typically in mountainous terrain, we investigated rainfall-runoff relations by measuring the maximum 30 min rainfall intensity and the unit-area peak discharge (peak discharge divided by the area burned) in three mountainous watersheds (17-26.8 km2) after a wildfire. We found rainfall-runoff relations that relate the unit-area peak discharges to the maximum 30 min rainfall intensities by a power law. These rainfall-runoff relations appear to have a threshold value for the maximum 30 min rainfall intensity (around 10 mm h-1) such that, above this threshold, the magnitude of the flood peaks increases more rapidly with increases in intensity. This rainfall intensity could be used to set threshold limits in rain gauges that are part of an early-warning flood system after wildfire. The maximum unit-area peak discharges from these three burned watersheds ranged from 3.2 to 50 m3 s-1 km-2. These values could provide initial estimates of the upper limits of runoff that can be used to predict floods after wildfires in mountainous terrain. Published in 2001 by John Wiley and Sons, Ltd.

New Raman-peak at 1850 cm(-1) observed in multiwalled carbon nanotubes produced by hydrogen arc discharge.

PubMed

Chen, B; Kadowaki, Y; Inoue, S; Ohkohchi, M; Zhao, X; Ando, Y

2010-06-01

The new peak (near 1850 cm(-1)) assigned to carbon linear chain included in the centre of very thin innermost multiwalled carbon nanotubes (MWNTs) has been verified by Raman spectroscopy. These MWNTs were produced by dc arc discharge of pure graphite rods in pure hydrogen gas and existed in the cathode deposit. In this paper, we clarified that the new Raman-peaks could also be observed in the cathode deposit including MWNTs produced by hydrogen dc arc discharge using graphite electrode with added Y or La. By changing the quantity of addition (Y or La), dc arc current and pressure of ambient hydrogen gas, the optimum condition to get maximum intensity of the new Raman-peaks was obtained. For the case of 1 wt% La, dc 50 A, H2 pressure of 50 Torr was found to be optimum, and the intensity of new Raman-peak was even higher than the G-band peak. For the case of 1 wt% Y, dc 50 A, H2 pressure of 50 Torr was optimum, but the intensity of new Raman-peak was weaker than the G-band peak. Transmission electron microscopy observation revealed that the crystallinity of MWNTs produced with pure graphite rod was better than those produced with added Y or La.

Cladding-pumped 70-kW-peak-power 2-ns-pulse Er-doped fiber amplifier

NASA Astrophysics Data System (ADS)

Khudyakov, M. M.; Bubnov, M. M.; Senatorov, A. K.; Lipatov, D. S.; Guryanov, A. N.; Rybaltovsky, A. A.; Butov, O. V.; Kotov, L. V.; Likhachev, M. E.

2018-02-01

An all-fiber pulsed erbium laser with pulse width of 2.4 ns working in a MOPA configuration has been created. Cladding pumped double clad erbium doped large mode area fiber was used in the final stage amplifier. Peculiarity of the current work is utilization of custom-made multimode diode wavelength stabilized at 981+/-0.5 nm - wavelength of maximum absorption by Er ions. It allowed us to shorten Er-doped fiber down to 1.7 m and keep a reasonably high pump-to signal conversion efficiency of 8.4%. The record output peak power for all-fiber amplifiers of 84 kW was achieved within 1555.9+/-0.15 nm spectral range.

Modeled future peak streamflows in four coastal Maine rivers

USGS Publications Warehouse

Hodgkins, Glenn A.; Dudley, Robert W.

2013-01-01

To safely and economically design bridges and culverts, it is necessary to compute the magnitude of peak streamflows that have specified annual exceedance probabilities (AEPs). Annual precipitation and air temperature in the northeastern United States are, in general, projected to increase during the 21st century. It is therefore important for engineers and resource managers to understand how peak flows may change in the future. This report, prepared in cooperation with the Maine Department of Transportation (MaineDOT), presents modeled changes in peak flows at four basins in coastal Maine on the basis of projected changes in air temperature and precipitation. To estimate future peak streamflows at the four basins in this study, historical values for climate (temperature and precipitation) in the basins were adjusted by different amounts and input to a hydrologic model of each study basin. To encompass the projected changes in climate in coastal Maine by the end of the 21st century, air temperatures were adjusted by four different amounts, from -3.6 degrees Fahrenheit (ºF) (-2 degrees Celsius (ºC)) to +10.8 ºF (+6 ºC) of observed temperatures. Precipitation was adjusted by three different percentage values from -15 percent to +30 percent of observed precipitation. The resulting 20 combinations of temperature and precipitation changes (includes the no-change scenarios) were input to Precipitation-Runoff Modeling System (PRMS) watershed models, and annual daily maximum peak flows were calculated for each combination. Modeled peak flows from the adjusted changes in temperature and precipitation were compared to unadjusted (historical) modeled peak flows. Annual daily maximum peak flows increase or decrease, depending on whether temperature or precipitation is adjusted; increases in air temperature (with no change in precipitation) lead to decreases in peak flows, whereas increases in precipitation (with no change in temperature) lead to increases in peak flows. As the magnitude of air temperatures increase in the four basins, peak flows decrease by larger amounts. If precipitation is held constant (no change from historical values), 17 to 26 percent decreases in peak flow occur at the four basins when temperature is increased by 7.2°F. If temperature is held constant, 26 to 38 percent increases in peak flow result from a 15-percent increase in precipitation. The largest decreases in peak flows at the four basins result from 15-percent decreases in precipitation combined with temperature increases of 10.8°F. The largest increases in peak flows generally result from 30-percent increases in precipitation combined with 3.6 °F decreases in temperatures. In many cases when temperature and precipitation both increase, small increases or decreases in annual daily maximum peak flows result. For likely changes projected for the northeastern United States for the middle of the 21st century (temperature increase of 3.6 °F and precipitation increases of 0 to 15 percent), peak-flow changes at the four coastal Maine basins in this study are modeled to be evenly distributed between increases and decreases of less than 25 percent. Peak flows with 50-percent and 1-percent AEPs (equivalent to 2-year and 100-year recurrence interval peak flows, respectively) were calculated for the four basins in the study using the PRMS-modeled annual daily maximum peak flows. Modeled peak flows with 50-percent and 1-percent AEPs with adjusted temperatures and precipitation were compared to unadjusted (historical) modeled values. Changes in peak flows with 50-percent AEPs are similar to changes in annual daily maximum peak flow; changes in peak flows with 1-percent AEPs are similar in pattern to changes in annual daily maximum peak flow, but some of the changes associated with increasing precipitation are much larger than changes in annual daily maximum peak flow. Substantial decreases in maximum annual winter snowpack water equivalent are modeled to occur with increasing air temperatures at the four basins in the study. (Snowpack is the snow on the ground that accumulates during a winter, and water equivalent is the amount of water in a snowpack if it were melted.) The decrease in modeled peak flows with increasing air temperature, given no change in precipitation amount, is likely caused by these decreases in winter snowpack and resulting decreases in snowmelt runoff. This Scientific Investigations Report, prepared in cooperation with the Maine Department of Transportation, presents a summary of modeled changes in peak flows at four basins in coastal Maine on the basis of projected changes in air temperature and precipitation. The full Fact Sheet (Hodgkins and Dudley, 2013) is available at http://pubs.usgs.gov/fs/2013/3021/.

On the road to self-sputtering in high power impulse magnetron sputtering: particle balance and discharge characteristics

NASA Astrophysics Data System (ADS)

Huo, Chunqing; Lundin, Daniel; Raadu, Michael A.; Anders, André; Tomas Gudmundsson, Jon; Brenning, Nils

2014-04-01

The onset and development of self-sputtering (SS) in a high power impulse magnetron sputtering (HiPIMS) discharge have been studied using a plasma chemical model and a set of experimental data, taken with an aluminum target and argon gas. The model is tailored to duplicate the discharge in which the data are taken. The pulses are long enough to include both an initial transient and a following steady state. The model is used to unravel how the internal discharge physics evolves with pulse power and time, and how it is related to features in the discharge current-voltage-time characteristics such as current densities, maxima, kinks and slopes. The connection between the self-sputter process and the discharge characteristics is quantified and discussed in terms of three parameters: a critical target current density Jcrit based on the maximum refill rate of process (argon) gas above the target, an SS recycling factor ΠSS-recycle, and an approximation \\tilde{\\alpha} of the probabilities of ionization of species that come from the target (both sputtered metal and embedded argon atoms). For low power pulses, discharge voltages UD ⩽ 380 V with peak current densities below ≈ 0.2 A cm-2, the discharge is found to be dominated by process gas sputtering. In these pulses there is an initial current peak in time, associated with partial gas rarefaction, which is followed by a steady-state-like plateau in all parameters similar to direct current magnetron sputtering. In contrast, high power pulses, with UD ⩾ 500 V and peak current densities above JD ≈ 1.6 A cm-2, make a transition to a discharge mode where SS dominates. The transition is found not to be driven by process gas rarefaction which is only about 10% at this time. Maximum gas rarefaction is found later in time and always after the initial peak in the discharge current. With increasing voltage, and pulse power, the discharge can be described as following a route where the role of SS increases in four steps: process gas sputtering, gas-sustained SS, self-sustained SS and SS runaway. At the highest voltage, 1000 V, the discharge is very close to, but does not go into, the SS runaway mode. This absence of runaway is proposed to be connected to an unexpected finding: that twice ionized ions of the target species play almost no role in this discharge, not even at the highest powers. This reduces ionization by secondary-emitted energetic electrons almost to zero in the highest power range of the discharge.

Lightweight Battery Charge Regulator Used to Track Solar Array Peak Power

NASA Technical Reports Server (NTRS)

Soeder, James F.; Button, Robert M.

1999-01-01

A battery charge regulator based on the series-connected boost regulator (SCBR) technology has been developed for high-voltage spacecraft applications. The SCBR regulates the solar array power during insolation to prevent battery overcharge or undercharge conditions. It can also be used to provide regulated battery output voltage to spacecraft loads if necessary. This technology uses industry-standard dc-dc converters and a unique interconnection to provide size, weight, efficiency, fault tolerance, and modularity benefits over existing systems. The high-voltage SCBR shown in the photograph has demonstrated power densities of over 1000 watts per kilogram (W/kg). Using four 150-W dc-dc converter modules, it can process 2500 W of power at 120 Vdc with a minimum input voltage of 90 Vdc. Efficiency of the SCBR was 94 to 98 percent over the entire operational range. Internally, the unit is made of two separate SCBR s, each with its own analog control circuitry, to demonstrate the modularity of the technology. The analog controllers regulate the output current and incorporate the output voltage limit with active current sharing between the two units. They also include voltage and current telemetry, on/off control, and baseplate temperature sensors. For peak power tracking, the SCBR was connected to a LabView-based data acquisition system for telemetry and control. A digital control algorithm for tracking the peak power point of a solar array was developed using the principle of matching the source impedance with the load impedance for maximum energy transfer. The algorithm was successfully demonstrated in a simulated spacecraft electrical system at the Boeing PhantomWorks High Voltage Test Facility in Seattle, Washington. The system consists of a 42-string, high-voltage solar array simulator, a 77-cell, 80-ampere-hour (A-hr) nickel-hydrogen battery, and a constant power-load module. The SCBR and the LabView control algorithm successfully tracked the solar array peak power point through various load transients, including sunlight discharge transients when the total load exceeded the maximum solar array output power.

Pu and 137Cs in the Yangtze River estuary sediments: distribution and source identification.

PubMed

Liu, Zhiyong; Zheng, Jian; Pan, Shaoming; Dong, Wei; Yamada, Masatoshi; Aono, Tatsuo; Guo, Qiuju

2011-03-01

Pu isotopes and (137)Cs were analyzed using sector field ICP-MS and γ spectrometry, respectively, in surface sediment and core sediment samples from the Yangtze River estuary. (239+240)Pu activity and (240)Pu/(239)Pu atom ratios (>0.18) shows a generally increasing trend from land to sea and from north to south in the estuary. This spatial distribution pattern indicates that the Pacific Proving Grounds (PPG) source Pu transported by ocean currents was intensively scavenged into the suspended sediment under favorable conditions, and mixed with riverine sediment as the water circulated in the estuary. This process is the main control for the distribution of Pu in the estuary. Moreover, Pu is also an important indicator for monitoring the changes of environmental radioactivity in the estuary as the river basin is currently the site of extensive human activities and the sea level is rising because of global climate changes. For core sediment samples the maximum peak of (239+240)Pu activity was observed at a depth of 172 cm. The sedimentation rate was estimated on the basis of the Pu maximum deposition peak in 1963-1964 to be 4.1 cm/a. The contributions of the PPG close-in fallout Pu (44%) and the riverine Pu (45%) in Yangtze River estuary sediments are equally important for the total Pu deposition in the estuary, which challenges the current hypothesis that the riverine Pu input was the major source of Pu budget in this area.

On the Origin of a Maximum Peak Pressure on the Target Outside of the Stagnation Point upon Normal Impact of a Blunt Projectile and with Underwater Explosion

NASA Astrophysics Data System (ADS)

Gonor, Alexander; Hooton, Irene

2006-07-01

Impact of a rigid projectile (impactor), against a metal target and a condensed explosive surface considered as the important process accompanying the normal entry of a rigid projectile into a target, was overlooked in the preceding studies. Within the framework of accurate shock wave theory, the flow-field, behind the shock wave attached to the perimeter of the adjoined surface, was defined. An important result is the peak pressure rises at points along the target surface away from the stagnation point. The maximum values of the peak pressure are 2.2 to 3.2 times higher for the metallic and soft targets (nitromethane, PBX 9502), than peak pressure values at the stagnation point. This effect changes the commonly held notion that the maximum peak pressure is reached at the projectile stagnation point. In the present study the interaction of a spherical decaying blast wave, caused by an underwater explosion, with a piece-wise plane target, having corner configurations, is investigated. The numerical calculation results in the determination of the vulnerable spots on the target, where the maximum peak overpressure surpassed that for the head-on shock wave reflection by a factor of 4.

Numerical Analysis of the Temperature Impact on Performance of GaN-Based 460-nm Light-Emitting Diode.

PubMed

Tawfik, Wael Z; Lee, June Key

2018-03-01

The influence of temperature on the characteristics of a GaN-based 460-nm light-emitting diode (LED) prepared on sapphire substrate was simulated using the SiLENSe and SpeCLED software programs. High temperatures impose negative effects on the performance of GaN-based LEDs. As the temperature increases, electrons acquire higher thermal energies, and therefore LEDs may suffer more from high-current loss mechanisms, which in turn causes a reduction in the radiative recombination rate in the active region. The internal quantum efficiency was reduced by about 24% at a current density of 35 A/cm2, and the electroluminescence spectral peak wavelength was redshifted. The LED operated at 260 K and exhibited its highest light output power of ~317.5 mW at a maximum injection current of 350 mA, compared to 212.2 mW for an LED operated at 400 K. However, increasing temperature does not cause a droop in efficiency under high injection conditions. The peak efficiency at 1 mA of injection current decreases more rapidly by ~15% with increasing temperature from 260 to 400 K than the efficiency at high injection current of 350 mA by ~11%.

Flood frequency analysis for nonstationary annual peak records in an urban drainage basin

USGS Publications Warehouse

Villarini, G.; Smith, J.A.; Serinaldi, F.; Bales, J.; Bates, P.D.; Krajewski, W.F.

2009-01-01

Flood frequency analysis in urban watersheds is complicated by nonstationarities of annual peak records associated with land use change and evolving urban stormwater infrastructure. In this study, a framework for flood frequency analysis is developed based on the Generalized Additive Models for Location, Scale and Shape parameters (GAMLSS), a tool for modeling time series under nonstationary conditions. GAMLSS is applied to annual maximum peak discharge records for Little Sugar Creek, a highly urbanized watershed which drains the urban core of Charlotte, North Carolina. It is shown that GAMLSS is able to describe the variability in the mean and variance of the annual maximum peak discharge by modeling the parameters of the selected parametric distribution as a smooth function of time via cubic splines. Flood frequency analyses for Little Sugar Creek (at a drainage area of 110 km2) show that the maximum flow with a 0.01-annual probability (corresponding to 100-year flood peak under stationary conditions) over the 83-year record has ranged from a minimum unit discharge of 2.1 m3 s- 1 km- 2 to a maximum of 5.1 m3 s- 1 km- 2. An alternative characterization can be made by examining the estimated return interval of the peak discharge that would have an annual exceedance probability of 0.01 under the assumption of stationarity (3.2 m3 s- 1 km- 2). Under nonstationary conditions, alternative definitions of return period should be adapted. Under the GAMLSS model, the return interval of an annual peak discharge of 3.2 m3 s- 1 km- 2 ranges from a maximum value of more than 5000 years in 1957 to a minimum value of almost 8 years for the present time (2007). The GAMLSS framework is also used to examine the links between population trends and flood frequency, as well as trends in annual maximum rainfall. These analyses are used to examine evolving flood frequency over future decades. ?? 2009 Elsevier Ltd.

Description of an aircraft lightning and simulated nuclear electromagnetic pulse (NEMP) threat based on experimental data

NASA Technical Reports Server (NTRS)

Rustan, Pedro L., Jr.

1987-01-01

Lightning data obtained by measuring the surface electromagnetic fields on a CV-580 research aircraft during 48 lightning strikes between 1500 and 18,000 feet in central Florida during the summers of 1984 and 1985, and nuclear electromagnetic pulse (NEMP) data obtained by surface electromagnetic field measurements using a 1:74 CV-580 scale model, are presented. From one lightning event, maximum values of 3750 T/s for the time rate of change of the surface magnetic flux density, and 4.7 kA for the peak current, were obtained. From the simulated NEMP test, maximum values of 40,000 T/s for the time rate of change of the surface magnetic flux density, and 90 A/sq m for the total normal current density, were found. The data have application to the development of a military aircraft lightning/NEMP standard.

Novel plasma source for safe beryllium spectral line studies in the presence of beryllium dust

NASA Astrophysics Data System (ADS)

Stankov, B. D.; Vinić, M.; Gavrilović Božović, M. R.; Ivković, M.

2018-05-01

Plasma source for beryllium spectral line studies in the presence of beryllium dust particles was realised. The guideline during construction was to prevent exposure to formed dust, considering the toxicity of beryllium. Plasma source characterization through determination of optimal working conditions is described. The necessary conditions for Be spectral line appearance and optimal conditions for line shape measurements are found. It is proven experimentally that under these conditions dust appears coincidently with the second current maximum. The electron density measured after discharge current maximum is determined from the peak separation of the hydrogen Balmer beta spectral line, and the electron temperature is determined from the ratios of the relative intensities of Be spectral lines emitted from successive ionized stages of atoms. Maximum values of electron density and temperature are measured to be 9.3 × 1022 m-3 and 16 800 K, respectively. Construction details and testing of the BeO discharge tube in comparison with SiO2 and Al2O3 discharge tubes are also presented in this paper.

Challenges and Opportunities for Biophotonic Devices in the Liquid State and the Solid State

DTIC Science & Technology

2006-07-01

of the NPB:Eu device and a baseline device (without the NPB layer and emitting from the Alq3 layer) as a function of current density. The luminance...of the NPB:Eu device is clearly superior, with a maximum of 590 cd/m2 at 375 mA/cm2, whereas the Alq3 OLED peaks at only 45 cd/m2 at 30 mA/cm2...Luminance versus current density for Eu-doped BioLED and for baseline Alq3 device. 1-4244-0078-3/06/$20.00 (c) 2006 IEEE B. Electrofluidic

CFD-Based Design Optimization Tool Developed for Subsonic Inlet

NASA Technical Reports Server (NTRS)

1995-01-01

The traditional approach to the design of engine inlets for commercial transport aircraft is a tedious process that ends with a less-than-optimum design. With the advent of high-speed computers and the availability of more accurate and reliable computational fluid dynamics (CFD) solvers, numerical optimization processes can effectively be used to design an aerodynamic inlet lip that enhances engine performance. The designers' experience at Boeing Corporation showed that for a peak Mach number on the inlet surface beyond some upper limit, the performance of the engine degrades excessively. Thus, our objective was to optimize efficiency (minimize the peak Mach number) at maximum cruise without compromising performance at other operating conditions. Using a CFD code NPARC, the NASA Lewis Research Center, in collaboration with Boeing, developed an integrated procedure at Lewis to find the optimum shape of a subsonic inlet lip and a numerical optimization code, ADS. We used a GRAPE-based three-dimensional grid generator to help automate the optimization procedure. The inlet lip shape at the crown and the keel was described as a superellipse, and the superellipse exponents and radii ratios were considered as design variables. Three operating conditions: cruise, takeoff, and rolling takeoff, were considered in this study. Three-dimensional Euler computations were carried out to obtain the flow field. At the initial design, the peak Mach numbers for maximum cruise, takeoff, and rolling takeoff conditions were 0.88, 1.772, and 1.61, respectively. The acceptable upper limits on the takeoff and rolling takeoff Mach numbers were 1.55 and 1.45. Since the initial design provided by Boeing was found to be optimum with respect to the maximum cruise condition, the sum of the peak Mach numbers at takeoff and rolling takeoff were minimized in the current study while the maximum cruise Mach number was constrained to be close to that at the existing design. With this objective, the optimum design satisfied the upper limits at takeoff and rolling takeoff while retaining the desirable cruise performance. Further studies are being conducted to include static and cross-wind operating conditions in the design optimization procedure. This work was carried out in collaboration with Dr. E.S. Reddy of NYMA, Inc.

Hot-carrier-induced current capability degradation and optimization for lateral IGBT on thick SOI substrate

NASA Astrophysics Data System (ADS)

Zhang, Chunwei; Li, Yang; Yue, Wenjing; Fu, Xiaoqian; Li, Zhiming

2018-07-01

In this paper, the hot-carrier-induced current capability degradation of a 600 V lateral insulated gate bipolar transistor (LIGBT) on thick silicon on insulator (SOI) substrate is investigated. Our experiments found that, for the SOI-LIGBT, the worst stress condition is the maximum gate voltage (Vgmax) condition and the current degradation is dominated by the damages in the channel region under the Vgmax stress condition. However, further analyses show that the influence of channel region damages on the collector current degradation increases with the increase of measured collector voltage and is maximum in the current saturation region. Therefore, in our opinion, the hot-carrier-induced current capability degradation of the SOI-LIGBT should be evaluated by the degradation of saturation current under the Vgmax stress condition. In addition, a novel SOI-LIGBT structure with an external p-type region was also proposed, which can alleviate the damage in the channel region by reducing the lateral electric field peak. Our experimental results demonstrate that the proposed structure could optimize the hot-carrier reliability effectively with the other characteristics maintained. He is currently a lecturer at the University of Jinan, Jinan, China. His research interests include power electronics, high voltage devices and the electronics reliability.

Are cooler surfaces a cost-effect mitigation of urban heat islands?

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

Pomerantz, Melvin

Much research has gone into technologies to mitigate urban heat islands by making urban surfaces cooler by increasing their albedos. To be practical, the benefit of the technology must be greater than its cost. Here, this report provides simple methods for quantifying the maxima of some benefits that albedo increases may provide. The method used is an extension of an earlier paper that estimated the maximum possible electrical energy saving achievable in an entire city in a year by a change of albedo of its surfaces. The present report estimates the maximum amounts and monetary savings of avoided CO 2more » emissions and the decreases in peak power demands. As examples, for several warm cities in California, a 0.2 increase in albedo of pavements is found to reduce CO 2 emissions by < 1 kg per m 2 per year. At the current price of CO 2 reduction in California, the monetary saving is < US$ 0.01 per year per m 2 modified. The resulting maximum peak-power reductions are estimated to be < 7% of the base power of the city. In conclusion, the magnitudes of the savings are such that decision-makers should choose carefully which urban heat island mitigation techniques are cost effective.« less

Are cooler surfaces a cost-effect mitigation of urban heat islands?

DOE PAGES

Pomerantz, Melvin

2017-04-20

Much research has gone into technologies to mitigate urban heat islands by making urban surfaces cooler by increasing their albedos. To be practical, the benefit of the technology must be greater than its cost. Here, this report provides simple methods for quantifying the maxima of some benefits that albedo increases may provide. The method used is an extension of an earlier paper that estimated the maximum possible electrical energy saving achievable in an entire city in a year by a change of albedo of its surfaces. The present report estimates the maximum amounts and monetary savings of avoided CO 2more » emissions and the decreases in peak power demands. As examples, for several warm cities in California, a 0.2 increase in albedo of pavements is found to reduce CO 2 emissions by < 1 kg per m 2 per year. At the current price of CO 2 reduction in California, the monetary saving is < US$ 0.01 per year per m 2 modified. The resulting maximum peak-power reductions are estimated to be < 7% of the base power of the city. In conclusion, the magnitudes of the savings are such that decision-makers should choose carefully which urban heat island mitigation techniques are cost effective.« less

A Computational approach in optimizing process parameters of GTAW for SA 106 Grade B steel pipes using Response surface methodology

NASA Astrophysics Data System (ADS)

Sumesh, A.; Sai Ramnadh, L. V.; Manish, P.; Harnath, V.; Lakshman, V.

2016-09-01

Welding is one of the most common metal joining techniques used in industry for decades. As in the global manufacturing scenario the products should be more cost effective. Therefore the selection of right process with optimal parameters will help the industry in minimizing their cost of production. SA 106 Grade B steel has a wide application in Automobile chassis structure, Boiler tubes and pressure vessels industries. Employing central composite design the process parameters for Gas Tungsten Arc Welding was optimized. The input parameters chosen were weld current, peak current and frequency. The joint tensile strength was the response considered in this study. Analysis of variance was performed to determine the statistical significance of the parameters and a Regression analysis was performed to determine the effect of input parameters over the response. From the experiment the maximum tensile strength obtained was 95 KN reported for a weld current of 95 Amp, frequency of 50 Hz and peak current of 100 Amp. With an aim of maximizing the joint strength using Response optimizer a target value of 100 KN is selected and regression models were optimized. The output results are achievable with a Weld current of 62.6148 Amp, Frequency of 23.1821 Hz, and Peak current of 65.9104 Amp. Using Die penetration test the weld joints were also classified in to 2 categories as good weld and weld with defect. This will also help in getting a defect free joint when welding is performed using GTAW process.

Plasma fluctuations in a Kaufman thruster

NASA Technical Reports Server (NTRS)

Serafini, J. S.; Terdan, F. F.

1973-01-01

Measurements of the RMS magnitude, spectra, and cross correlations for the fluctuations in the beam, discharge, and neutralizer keeper currents are presented for a 30 cm diameter dished grid ion thruster for a range of magnetic baffle currents. The ratio of RMS to mean ion beam current varied from 0.04 to 0.23. The spectra of the amplitudes of the beam and discharge current fluctuations were taken up to 9 MHz and show that the predominant amplitudes occur at frequencies of 10 kHz or below. The falloff with increasing frequency is rapid. Frequencies above 100 kHz the spectral levels are 45 kb or more below the maximum peak amplitudes. The cross correlations revealed the ion beam fluctuations to have large radial and axial scales.

Sleep spindle alterations in patients with Parkinson's disease

PubMed Central

Christensen, Julie A. E.; Nikolic, Miki; Warby, Simon C.; Koch, Henriette; Zoetmulder, Marielle; Frandsen, Rune; Moghadam, Keivan K.; Sorensen, Helge B. D.; Mignot, Emmanuel; Jennum, Poul J.

2015-01-01

The aim of this study was to identify changes of sleep spindles (SS) in the EEG of patients with Parkinson's disease (PD). Five sleep experts manually identified SS at a central scalp location (C3-A2) in 15 PD and 15 age- and sex-matched control subjects. Each SS was given a confidence score, and by using a group consensus rule, 901 SS were identified and characterized by their (1) duration, (2) oscillation frequency, (3) maximum peak-to-peak amplitude, (4) percent-to-peak amplitude, and (5) density. Between-group comparisons were made for all SS characteristics computed, and significant changes for PD patients vs. control subjects were found for duration, oscillation frequency, maximum peak-to-peak amplitude and density. Specifically, SS density was lower, duration was longer, oscillation frequency slower and maximum peak-to-peak amplitude higher in patients vs. controls. We also computed inter-expert reliability in SS scoring and found a significantly lower reliability in scoring definite SS in patients when compared to controls. How neurodegeneration in PD could influence SS characteristics is discussed. We also note that the SS morphological changes observed here may affect automatic detection of SS in patients with PD or other neurodegenerative disorders (NDDs). PMID:25983685

ESTIMATING RISK TO CALIFORNIA ENERGY INFRASTRUCTURE FROM PROJECTED CLIMATE CHANGE

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

Sathaye, Jayant; Dale, Larry; Larsen, Peter

2011-06-22

This report outlines the results of a study of the impact of climate change on the energy infrastructure of California and the San Francisco Bay region, including impacts on power plant generation; transmission line and substation capacity during heat spells; wildfires near transmission lines; sea level encroachment upon power plants, substations, and natural gas facilities; and peak electrical demand. Some end-of-century impacts were projected:Expected warming will decrease gas-fired generator efficiency. The maximum statewide coincident loss is projected at 10.3 gigawatts (with current power plant infrastructure and population), an increase of 6.2 percent over current temperature-induced losses. By the end ofmore » the century, electricity demand for almost all summer days is expected to exceed the current ninetieth percentile per-capita peak load. As much as 21 percent growth is expected in ninetieth percentile peak demand (per-capita, exclusive of population growth). When generator losses are included in the demand, the ninetieth percentile peaks may increase up to 25 percent. As the climate warms, California's peak supply capacity will need to grow faster than the population.Substation capacity is projected to decrease an average of 2.7 percent. A 5C (9F) air temperature increase (the average increase predicted for hot days in August) will diminish the capacity of a fully-loaded transmission line by an average of 7.5 percent.The potential exposure of transmission lines to wildfire is expected to increase with time. We have identified some lines whose probability of exposure to fire are expected to increase by as much as 40 percent. Up to 25 coastal power plants and 86 substations are at risk of flooding (or partial flooding) due to sea level rise.« less

Electroluminescence properties of LEDs based on electron-irradiated p-Si

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

Sobolev, N. A., E-mail: nick@sobolev.ioffe.rssi.ru; Shtel’makh, K. F.; Kalyadin, A. E.

2016-02-15

The electroluminescence (EL) in n{sup +}–p–p{sup +} light-emitting-diode (LED) structures based on Si irradiated with electrons and annealed at high temperature is studied. The LEDs are fabricated by the chemical- vapor deposition of polycrystalline silicon layers doped with high concentrations of boron and phosphorus. Transformation of the EL spectra with current in the LEDs is well described by six Gaussian curves. The peak positions of these curves are current-independent and equal to 1233, 1308, 1363, 1425, 1479, and 1520 nm. The dependences of the integrated EL intensity and of the full-width at half-maximum (FWHM) of the lines on current aremore » examined.« less

Study on the mechanism of Si-glass-Si two step anodic bonding process

NASA Astrophysics Data System (ADS)

Hu, Lifang; Wang, Hao; Xue, Yongzhi; Shi, Fangrong; Chen, Shaoping

2018-04-01

Si-glass-Si was successfully bonded together through a two-step anodic bonding process. The bonding current in each step of the two-step bonding process was investigated, and found to be quite different. The first bonding current decreased quickly to a relatively small value, but for the second bonding step, there were two current peaks; the current first decreased, then increased, and then decreased again. The second current peak occurred earlier with higher temperature and voltage. The two-step anodic bonding process was investigated in terms of bonding current. SEM and EDS tests were conducted to investigate the interfacial structure of the Si-glass-Si samples. The two bonding interfaces were almost the same, but after an etching process, transitional layers could be found in the bonding interface and a deeper trench with a thickness of ~1.5 µm could be found in the second bonding interface. Atomic force microscopy mapping results indicated that sodium precipitated from the back of the glass, which makes the roughness of the surface become coarse. Tensile tests indicated that the fracture occurred at the glass substrate and that the bonding strength increased with the increment of bonding temperature and voltage with the maximum strength of 6.4 MPa.

The action of alcohols and other non-ionic surface active substances on the sodium current of the squid giant axon.

PubMed Central

Haydon, D A; Urban, B W

1983-01-01

The effects of several n-alkanols and n-alkyl oxyethylene alcohols, methyl octanoate, glycerol 1-monooctanoate and dioctanoyl phosphatidylcholine on the ionic currents and electrical capacity of the squid giant axon membrane have been examined. The peak inward current in voltage-clamped axons was reduced reversibly by each substance. For n-pentanol to n-decanol the concentrations required to suppress the peak inward current by 50% were determined. From these data, it was estimated that the standard free energy per CH2 for adsorption to the site of action was -3.04 kJ mole-1, as compared with -3.11 kJ mole-1 for adsorption into phospholipid bilayers or an n-alkane/aqueous solution interface. The membrane capacity at 100 kHz was not greatly by any of the test substances at concentrations which reduced the inward current by 50%. Na currents under voltage clamp were recorded in intracellularly perfused axons before, during and sometimes after exposure to the test substances and the records were fitted with equations similar to those proposed by Hodgkin & Huxley (1952). Shifts in the curves of the steady-state activation and inactivation parameters (m infinity and h infinity) against membrane potential, changes in the peak heights of the activation and inactivation time constants (tau m and tau h) and reductions in the maximum Na conductance (gNa) have been tabulated. All of the test substances shifted the voltage dependence of the steady-state activation in the depolarizing direction and lowered the peak time constants for both activation and inactivation. The origins of these effects, and of the differences in the present results from those of the hydrocarbons (Haydon & Urban, 1983), have been discussed in terms of the physico-chemical properties of the two groups of substances and with reference to their effects on artificial membranes. PMID:6312030

Solar maximum: Solar array degradation

NASA Technical Reports Server (NTRS)

Miller, T.

1985-01-01

The 5-year in-orbit power degradation of the silicon solar array aboard the Solar Maximum Satellite was evaluated. This was the first spacecraft to use Teflon R FEP as a coverglass adhesive, thus avoiding the necessity of an ultraviolet filter. The peak power tracking mode of the power regulator unit was employed to ensure consistent maximum power comparisons. Telemetry was normalized to account for the effects of illumination intensity, charged particle irradiation dosage, and solar array temperature. Reference conditions of 1.0 solar constant at air mass zero and 301 K (28 C) were used as a basis for normalization. Beginning-of-life array power was 2230 watts. Currently, the array output is 1830 watts. This corresponds to a 16 percent loss in array performance over 5 years. Comparison of Solar Maximum Telemetry and predicted power levels indicate that array output is 2 percent less than predictions based on an annual 1.0 MeV equivalent election fluence of 2.34 x ten to the 13th power square centimeters space environment.

Moderate Geomagnetic Storms: Interplanetary Origins and Coupling Functions (ISEE3 Data)

NASA Technical Reports Server (NTRS)

Mendes, Odim, Jr.; Gonzalez, W. D.; Gonzalez, A. L. C.; Pinto, O., Jr.; Tsurutani, B. T.

1996-01-01

Geomagnetic storms are related to the ring current intensification, which is driven by energy injection primarily during energetic solar wind-magnetosphere coupling due to reconnection at the magnetopause. This work identified the interplanetary origins of moderate geomagnetic storms (-100nT is less or equal to Dst(sub peak) is less than or equal to -50 nT) and analyzed the coupling processes during the storm main phase at solar maximum (1978-1979).

On the suitability of the copula types for the joint modelling of flood peaks and volumes along the Danube River

NASA Astrophysics Data System (ADS)

Kohnová, Silvia; Papaioannou, George; Bacigál, Tomáš; Szolgay, Ján; Hlavčová, Kamila; Loukas, Athanasios; Výleta, Roman

2017-04-01

Flood frequency analysis is often performed as a univariate analysis of flood peaks using a suitable theoretical probability distribution of the annual maximum flood peaks or peak over threshold values. However, also other flood attributes, such as flood volume and duration, are often necessary for the design of hydrotechnical structures and projects. In this study, the suitability of various copula families for a bivariate analysis of peak discharges and flood volumes has been tested on the streamflow data from gauging stations along the whole Danube River. Kendall's rank correlation coefficient (tau) quantifies the dependence between flood peak discharge and flood volume settings. The methodology is tested on two different data samples: 1) annual maximum flood (AMF) peaks with corresponding flood volumes, which is a typical choice for engineering studies and 2). annual maximum flood (AMF) peaks combined with annual maximum flow volumes of fixed durations at 5, 10, 15, 20, 25, 30 and 60 days, which can be regarded as a regime analysis of the dependence between the extremes of both variables in a given year. The bivariate modelling of the peak discharge - flood volume couples is achieved with the use of the the following copulas: Ali-Mikhail-Haq (AMH), Clayton, Frank, Joe, Gumbel, HuslerReiss, Galambos, Tawn, Normal, Plackett and FGM, respectively. Scatterplots of the observed and simulated peak discharge - flood volume pairs and goodness-of-fit tests have been used to assess the overall applicability of the copulas as well as observing any changes in suitable models along the Danube River. The results indicate that, almost all of the considered Archimedean class copulas (e.g. Frank, Clayton and Ali-Mikhail-Haq) perform better than the other copula families selected for this study, and that for the second data samples mostly the upper-tail-flat copulas were suitable.

Competition between ionic adsorption and desorption on electrochemical double layer capacitor electrodes in acetonitrile solutions at different currents and temperatures

NASA Astrophysics Data System (ADS)

Park, Sieun; Kang, Seok-Won; Kim, Ketack

2017-12-01

The operation of electrochemical double layer capacitors at high currents and viscosities and at low temperatures is difficult. Under these conditions, ion transport is limited, and some of the electrode area is unavailable for adsorption, which results in a low capacitance. Increasing the temperature helps to increase the ionic movement, leading to enhanced adsorption and increased capacitance. In contrast, ion desorption (self-discharge) surpasses the capacitance improvement when ions gain a high amount of energy with increasing temperature. For example, temperatures as high as 70 °C cause a very high rate of ionic desorption in acetonitrile solutions in which the individual properties of the two electrolytes-tetraethylammonium tetrafluoroborate (TEA BF4) and ethylmethylimidazolium tetrafluoroborate (EMI BF4)-are not distinguishable. The capacitance improvement and self-discharge are balanced, resulting in a capacitance peak at mid-range temperatures, i.e., 35-45 °C, in the more viscous electrolyte, i.e., TEA BF4. The less viscous electrolyte, i.e., EMI BF4 has a wider capacitance peak from 25 to 45 °C and higher capacitance than that of TEA BF4. Because the maximum power is obtained in the mid-temperature range (35-45 °C), it is necessary to control the viscosity and temperature to obtain the maximum power in a given device.

The effects of some inhalation anaesthetics on the sodium current of the squid giant axon.

PubMed Central

Haydon, D A; Urban, B W

1983-01-01

The effects of diethyl ether, methoxyflurane, halothane, dichloromethane and chloroform on the ionic currents and electrical capacity of the squid giant axon have been examined. The peak inward current in voltage-clamped axons was reduced reversibly by each substance. Sodium currents under voltage clamp were recorded in intracellularly perfused axons before, during, and sometimes after exposure to the test substances, and the records were fitted with equations similar to those proposed by Hodgkin & Huxley (1952). Shifts in the dependence of the steady-state activation and inactivation parameters (m infinity and h infinity) on membrane potential, reductions in the peak heights of the activation and inactivation time constants (tau m and tau h) and decreases in the maximum Na conductance (gNa) have been tabulated. For each of the anaesthetics the steady-state inactivation curve was shifted in the hyperpolarizing direction though less markedly than for the hydrocarbons. The steady-state activation curve was in each instance shifted in the depolarizing direction, as for the alcohols and other surface active substances. In common with both the hydrocarbons and the surface active substances the peak time constants were invariably reduced. The membrane capacity at 100 kHz was affected significantly only by methoxyflurane, where decreases of ca. 9% were observed for 3 mM solutions. The extent to which the results can be accounted for in terms of the perturbation of membrane lipid has been discussed. PMID:6312031

Carbon nanotube modified glassy carbon electrode for electrochemical oxidation of alkylphenol ethoxylate.

PubMed

Patiño, Yolanda; Díaz, Eva; Lobo-Castañón, María Jesús; Ordóñez, Salvador

2018-06-01

Electrochemical oxidation of an emerging pollutant, 2-(4-methylphenoxy)ethanol (MPET), from water has been studied by cyclic voltammetry (CV). Multiwall carbon nanotubes glassy carbon electrodes (MWCNT-GCE) were used as working electrode due to their extraordinary properties. The oxidation process is irreversible, since no reduction peaks were observed in the reverse scan. The electrocatalytic effect of MWCNT was confirmed as the oxidation peak intensity increases in comparison to bare-GCE. The effect of functional groups on MWCNT was also studied by MWCNT functionalized with NH 2 (MWCNT-NH 2 ) and COOH (MWCNT-COOH) groups. The oxidation peak current decreases in the following order: MWCNT > MWCNT-NH 2 > MWCNT-COOH. Taking into account the normalized peak current, MWCNT-NH 2 exhibits the best results due to its strong interaction with MPET. Under optimal conditions (pH = 5.0 and volume of MWCNT = 10 μL), degradation was studied for MWCNT-GCE and MWCNT-NH 2 -GCE. A complete MPET removal was observed using MWCNT-GCE after four CV cycles, for a volume/area (V/A) ratio equal to 19. In the case of MWCNT-NH 2 -GCE, the maximum MPET removal was close to 90% for V/A = 37, higher than that obtained for MWCNT-GCE at the same conditions (≈80%). In both cases, no organic by-products were detected.

Evaluation of Drying Process on the Composition of Black Pepper Ethanolic Extract by High Performance Liquid Chromatography With Diode Array Detector

PubMed Central

Namjoyan, Foroogh; Hejazi, Hoda; Ramezani, Zahra

2012-01-01

Background Black pepper (Piper nigrum) is one of the well-known spices extensively used worldwide especially in India, and Southeast Asia. The presence of alkaloids in the pepper, namely, piperine and its three stereoisomers, isopiperine, chavicine and isochavicine are well noticed. Objectives The current study evaluated the effect of lyophilization and oven drying on the stability and decomposition of constituents of black pepper ethanolic extract. Materials and Methods In the current study ethanolic extract of black pepper obtained by maceration method was dried using two methods. The effect of freeze and oven drying on the chemical composition of the extract especially piperine and its three isomers were evaluated by HPLC analysis of the ethanolic extract before and after drying processes using diode array detector. The UV Vis spectra of the peaks at piperine retention time before and after each drying methods indicated maximum absorbance at 341.2 nm corresponding to standard piperine. Results The results indicated a decrease in intensity of the chromatogram peaks at approximately all retention times after freeze drying, indicating a few percent loss of piperine and its isomers upon lyophilization. Two impurity peaks were completely removed from the extract. Conclusions In oven dried samples two of the piperine stereoisomers were completely removed from the extract and the intensity of piperine peak was increased. PMID:24624176

Characterization of peak capacity of microbore liquid chromatography columns using gradient kinetic plots.

PubMed

Hetzel, Terence; Blaesing, Christina; Jaeger, Martin; Teutenberg, Thorsten; Schmidt, Torsten C

2017-02-17

The performance of micro-liquid chromatography columns with an inner diameter of 0.3mm was investigated on a dedicated micro-LC system for gradient elution. Core-shell as well as fully porous particle packed columns were compared on the basis of peak capacity and gradient kinetic plot limits. The results for peak capacity showed the superior performance of columns packed with sub-2μm fully porous particles compared to 3.0μm fully porous and 2.7μm core-shell particles within a range of different gradient time to column void time ratios. For ultra-fast chromatography a maximum peak capacity of 16 can be obtained using a 30s gradient for the sub-2μm fully porous particle packed column. A maximum peak capacity of 121 can be achieved using a 5min gradient. In addition, the influence of an alternative detector cell on the basis of optical waveguide technology and contributing less to system variance was investigated showing an increased peak capacity for all applied gradient time/column void time ratios. Finally, the influence of pressure was evaluated indicating increased peak capacity for maximum performance whereas a limited benefit for ultra-fast chromatography with gradient times below 30s was observed. Copyright © 2017 Elsevier B.V. All rights reserved.

A simple multi-scale Gaussian smoothing-based strategy for automatic chromatographic peak extraction.

PubMed

Fu, Hai-Yan; Guo, Jun-Wei; Yu, Yong-Jie; Li, He-Dong; Cui, Hua-Peng; Liu, Ping-Ping; Wang, Bing; Wang, Sheng; Lu, Peng

2016-06-24

Peak detection is a critical step in chromatographic data analysis. In the present work, we developed a multi-scale Gaussian smoothing-based strategy for accurate peak extraction. The strategy consisted of three stages: background drift correction, peak detection, and peak filtration. Background drift correction was implemented using a moving window strategy. The new peak detection method is a variant of the system used by the well-known MassSpecWavelet, i.e., chromatographic peaks are found at local maximum values under various smoothing window scales. Therefore, peaks can be detected through the ridge lines of maximum values under these window scales, and signals that are monotonously increased/decreased around the peak position could be treated as part of the peak. Instrumental noise was estimated after peak elimination, and a peak filtration strategy was performed to remove peaks with signal-to-noise ratios smaller than 3. The performance of our method was evaluated using two complex datasets. These datasets include essential oil samples for quality control obtained from gas chromatography and tobacco plant samples for metabolic profiling analysis obtained from gas chromatography coupled with mass spectrometry. Results confirmed the reasonability of the developed method. Copyright © 2016 Elsevier B.V. All rights reserved.

Collateral Damage to Satellites from an EMP Attack

DTIC Science & Technology

2010-08-01

peak dose is computed in an infinite half plane of silicon. The resulting in- plane stresses in silicon are shown in Figure VI.23. In- plane refers to...achieved by the SLAR coating 81 Figure VIII.6. Ratio of the peak in- plane compressive stress to the maximum compressive stress for the SLAR coating...82 Figure VIII.7. Maximum in- plane compressive stress in a SLAR coating on DMSP/NOAA subjected to the threat events 83 Figure VIII.8. Maximum in

Osteoclastogenesis in Local Alveolar Bone in Early Decortication-Facilitated Orthodontic Tooth Movement

PubMed Central

Liu, Chang; Jiang, Yu-Xi; Qu, Hong; Li, Cui-Ying; Jiang, Jiu-Hui

2016-01-01

Objective In the current study, we aimed to investigate the effects of alveolar decortication on local bone remodeling, and to explore the possible mechanism by which decortication facilitates tooth movement. Materials and Methods Forty rabbits were included in the experiment. The left mandible was subjected to decortication-facilitated orthodontics, and the right mandible underwent traditional orthodontics as a control. The animals were sacrificed on the days 1, 3, 5, 7 and 14, after undergoing orthodontic procedures. Tooth movement was measured by Micro-CT, and the local periodontal tissues were investigated using H&E, Masson's trichrome and tartrate-resistant acid phosphatase (TRAP) staining. The mRNA levels of genes related to bone remodeling in the alveolar bone were analyzed using real-time PCR. Result On days 3, 5, 7 and 14, tooth movement was statistically accelerated by decortication (P < 0.05) and was accompanied by increased hyperemia. Despite the lack of new bone formation in both groups, more osteoclasts were noted in the decorticated group, with two peak counts (P < 0.05). The first peak count was consistent with the maximum values of ctsk and TRAP expression, and the second peak counts accompanied the maximum nfatc1 and jdp2 expression. The increased fra2 expression and the ratio of rankl/opg also accompanied the second peak counts. Conclusions Following alveolar decortication, osteoclastogenesis was initially induced to a greater degree than the new bone formation which was thought to have caused a regional acceleratory phenomenon (RAP). The amount of steoclastogenesis in the decorticated alveolar bone was found to have two peaks, perhaps due to attenuated local resistance. The first peak count in osteoclasts may have been due to previously existing osteoclast precursors, whereas the second may represent the differentiation of peripheral blood mononuclear cells which came from circulation as the result of hyperemia. PMID:27096621

Power Management for Space Advanced Life Support

NASA Technical Reports Server (NTRS)

Jones, Harry

2001-01-01

Space power systems include the power source, storage, and management subsystems. In current crewed spacecraft, solar cells are the power source, batteries provide storage, and the crew performs any required load scheduling. For future crewed planetary surface systems using Advanced Life Support, we assume that plants will be grown to produce much of the crew's food and that nuclear power will be employed. Battery storage is much more costly than nuclear power capacity and so is not likely to be used. We investigate the scheduling of power demands by the crew or automatic control, to reduce the peak power load and the required generating capacity. The peak to average power ratio is a good measure of power use efficiency. We can easily schedule power demands to reduce the peak power from its maximum, but simple scheduling approaches may not find the lowest possible peak to average power ratio. An initial power scheduling example was simple enough for a human to solve, but a more complex example with many intermittent load demands required automatic scheduling. Excess power is a free resource and can be used even for minor benefits.

n-ZnO/p-4H-SiC diode: Structural, electrical, and photoresponse characteristics

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

Guziewicz, M., E-mail: margu@ite.waw.pl; Jung, W.; Schifano, R.

Epitaxial n-type ZnO film has been grown, on a commercial 5 μm thick p-type 4H-SiC(00.1) Al doped epilayer, by atomic layer deposition. A full width at half maximum of the ZnO 00.2 diffraction peak rocking curve of 0.34°{sup  }± 0.02° has been measured. Diodes formed on the n-ZnO/p-4H-SiC heterostructure show rectifying behavior with a forward to reverse current ratio at the level of 10{sup 9} at ±4 V, a leakage current density of ∼6 × 10{sup −8} A/cm{sup 2}, and a low ideality factor equal to 1.17 ± 0.04. In addition, the diodes exhibit selective photoresponse with a maximum at 367 nm, and with a current increasemore » of ∼10{sup 3} under illuminations with respect to the dark value, which makes such devices prospective candidates for ultraviolet light sensors.« less

Electron energy distributions measured during electron beam/plasma interactions. [in E region

NASA Technical Reports Server (NTRS)

Jost, R. J.; Anderson, H. R.; Mcgarity, J. O.

1980-01-01

In the large vacuum facility at the NASA-Johnson Space Center an electron beam was projected 20 m parallel to B from a gun with variable accelerating potential (1.0 to 2.5 kV) to an aluminum target. The ionospheric neutral pressure and field were approximated. Beam electron energy distributions were measured directly using an electrostatic deflection analyzer and indirectly with a detector that responded to the X-rays produced by electron impact on the target. At low currents the distribution is sharply peaked at the acceleration potential. At high currents a beam plasma discharge occurs and electrons are redistributed in energy so that the former energy peak broadens to 10-15 percent FWHM with a strongly enhanced low energy tail. At the 10% of maximum point the energy spectrum ranges from less than 1/2 to 1.2 times the gun energy. The effect is qualitatively the same at all pitch angles and locations sampled.

A comparison of different powder compaction processes adopted for synthesis of lead-free piezoelectric ceramics

NASA Astrophysics Data System (ADS)

Mahesh, M. L. V.; Bhanu Prasad, V. V.; James, A. R.

2016-04-01

Barium zirconium titanate, Ba(Zr0.15Ti0.85)O3 nano-crystalline powders were synthesized using high energy ball milling. The calcined powders were compacted adopting two different approaches viz. the conventional uniaxial pressing and cold-isostatic pressing (CIP) and the compacts were sintered at 1350 °C. A single phase perovskite structure was observed in both cases. BZT ceramics compacted using CIP technique exhibited enhanced dielectric and ferroelectric properties compared to ceramics compacted by uniaxial pressing. The polarization current peaks have been used in this paper as an experimental evidence to prove the existence of ferroelectricity in the BZT ceramics under study. The peak polarization current was found to be ~700% higher in case of cold iso-statically compacted ceramics. Similarly electric field induces strain showed a maximum strain ( S max) of 0.08% at an electric field of 28 kV/cm. The dielectric and ferroelectric properties observed are comparable to single crystals of the same material.

Caffeine depression of spontaneous activity in rabbit sino-atrial node cells.

PubMed

Satoh, H

1993-05-01

1. Effects of caffeine on the action potentials and the membrane currents in spontaneously beating rabbit sino-atrial (SA) node cells were examined using a two-microelectrode technique. 2. Cumulative administrations of caffeine (1-10 mM) caused a negative chronotropic effect in a concentration-dependent manner, which was not modified by atropine (0.1 microM). At 10 mM, caffeine increased the amplitude and prolonged the duration of action potentials significantly; the other parameters were unaffected. 3. In 3 of 16 preparations, caffeine (5 mM) elicited arrhythmia. At high Ca2+ (8.1 mM), caffeine (5 mM) increased the incidence of arrhythmia. 4. Caffeine (0.5-10 mM) enhanced the slow inward current, but at 10 mM decreased the enhanced peak current by 5 mM. The hyperpolarization-activated inward current was also enhanced by caffeine, but 10 mM caffeine decreased the current peak as compared with that at 5 mM. In addition, caffeine inhibited the delayed rectifying outward current in a concentration-dependent manner, accompanied by a depressed activation curve without any shift in the half-maximum activation voltage. 5. Caffeine elevated the cytoplasmic Ca2+ level in the SA node cells loaded with Ca(2+)-sensitive fluorescent dye (fura-2). 6. These results suggest that caffeine enhances and/or inhibits the ionic currents and elicits arrhythmia due to the induction of cellular calcium overload.

Effect of σ2 on All Aspects of Failure in Rocks from Granite to Sandstone

NASA Astrophysics Data System (ADS)

Haimson, B. C.; Ma, X.

2014-12-01

We have studied the effect of σ2 on failure characteristics of two crystalline and three clastic rocks subjected to true triaxial stresses. Common to all rocks tested is the rise in both strain localization onset and σ1 at failure (σ1,peak) for a given σ3, as σ2 is elevated beyond its base level (σ2 = σ3). σ1,peak reaches a maximum at some level of σ2, beyond which it gradually declines, approaching its base magnitude when σ2 nears its own maximum. Failure-plane angle with respect to σ1 for a given σ3 also increases with σ2, at least until the maximum σ1,peak is reached. Westerly granite (Haimson and Chang, IJRMMS, 2000) and KTB amphibolite (Chang and Haimson, JGR, 2000), exhibited a dramatic σ2 effect: at low σ3 (20-30 MPa), higher σ2 lifted σ1,peak by up to 50% over its base level. At high σ3, the increase in σ1,peak was reduced, but even at σ3 = 100 MPa, maximum σ1,peak in both rocks was over 20% higher than its base level. Failure mode remained brittle throughout the stress range tested, but the onset of dilatancy rose with σ2, as did the failure-plane (shear-band) angle (by up to 20°). A gentler effect of σ2 on σ1, peak and failure-plane angle was observed in the clastics, and that effect subsided as porosity increased. In low porosity (φ = 7%) TCDP siltstone (Oku, et al, GRL, 2007), the maximum σ1,peak at σ3 = 25 MPa was about 30% larger than at σ2 = σ3 level, and only 12.5% larger at σ3 = 100 MPa. Failure mode stayed brittle throughout, but shear-band angle increase with σ2 was limited to about 10°, irrespective of σ3 level. An even smaller σ2 effect was observed in Coconino sandstone (φ = 17%) (Ma, PhD thesis, 2014). σ1,peak reached a maximum of about 10% higher than at σ2 = σ3 level; failure-plane angle rise with σ2 was less than 10°. The weakest σ2 effect was found in the high porosity (φ= 25%) Bentheim sandstone (Ma, PhD thesis, 2014). Here σ1, peak reached a maximum of well under 10% higher than its base magnitude, regardless of σ3 level; average failure-plane angle rise with σ2 was below 10°. Failure at σ3 = 150 MPa was along a compaction band(s) normal to σ1, regardless of σ2. Both Coconino and Bentheim underwent dilatant failure at low σ3, shifting to compactive failure at high σ3 levels. But σ2 also affected the failure mode: compactive failure at σ2 = σ3 gradually reverted to a dilatant mode as σ2 was raised.

Eddy current testing probe with dual half-cylindrical coils

NASA Astrophysics Data System (ADS)

Bae, Byung-Hoon; Choi, Jung-Mi; Kim, Soo-Yong

2000-02-01

We have developed a new eddy current probe composed of a dual half-cylindrical (2HC) coil as an exciting coil and a sensing coil that is placed in the small gap of the 2HC coil. The 2HC coil induces a linear eddy current on the narrow region within the target medium. The magnitude of eddy current has a maximum peak with the narrow width, underneath the center of the exciting 2HC coil. Because of the linear eddy current, the probe can be used to detect not only the existence of a crack but also its direction in conducting materials. Using specimen with a machined crack, and varying the exciting frequency from 0.5 to 100 kHz, we investigated the relationships between the direction of crack and the output voltage of the sensing coil.

Critical current oscillations of elliptical Josephson junctions with single-domain ferromagnetic layers

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

Glick, Joseph A.; Khasawneh, Mazin A.; Niedzielski, Bethany M.

We report that josephson junctions containing ferromagnetic layers are of considerable interest for the development of practical cryogenic memory and superconducting qubits. Such junctions exhibit a ground-state phase shift of π for certain ranges of ferromagnetic layer thicknesses. We present studies of Nb based micron-scale elliptically shaped Josephson junctions containing ferromagnetic barriers of Ni 81Fe 19 or Ni 65Fe 15Co 20. By applying an external magnetic field, the critical current of the junctions is found to follow characteristic Fraunhofer patterns and display sharp switching behavior suggestive of single-domain magnets. The high quality of the Fraunhofer patterns enables us to extractmore » the maximum value of the critical current even when the peak is shifted significantly outside the range of the data due to the magnetic moment of the ferromagnetic layer. The maximum value of the critical current oscillates as a function of the ferromagnetic barrier thickness, indicating transitions in the phase difference across the junction between values of zero and π. Lastly, we compare the data to previous work and to models of the 0-π transitions based on existing theories.« less

Critical current oscillations of elliptical Josephson junctions with single-domain ferromagnetic layers

DOE PAGES

Glick, Joseph A.; Khasawneh, Mazin A.; Niedzielski, Bethany M.; ...

2017-10-06

We report that josephson junctions containing ferromagnetic layers are of considerable interest for the development of practical cryogenic memory and superconducting qubits. Such junctions exhibit a ground-state phase shift of π for certain ranges of ferromagnetic layer thicknesses. We present studies of Nb based micron-scale elliptically shaped Josephson junctions containing ferromagnetic barriers of Ni 81Fe 19 or Ni 65Fe 15Co 20. By applying an external magnetic field, the critical current of the junctions is found to follow characteristic Fraunhofer patterns and display sharp switching behavior suggestive of single-domain magnets. The high quality of the Fraunhofer patterns enables us to extractmore » the maximum value of the critical current even when the peak is shifted significantly outside the range of the data due to the magnetic moment of the ferromagnetic layer. The maximum value of the critical current oscillates as a function of the ferromagnetic barrier thickness, indicating transitions in the phase difference across the junction between values of zero and π. Lastly, we compare the data to previous work and to models of the 0-π transitions based on existing theories.« less

Effects of a 6-Week Bench Press Program Using the Freak Bar in a Sample of Collegiate Club Powerlifters.

PubMed

Ghigiarelli, Jamie J; Pelton, Luke M; Gonzalez, Adam M; Fulop, Andras M; Gee, Joshua Y; Sell, Katie M

2018-04-01

Ghigiarelli, JJ, Pelton, LM, Gonzalez, AM, Fulop, AM, Gee, JY, and Sell, KM. Effects of a 6-week bench press program using the freak bar in a sample of collegiate club powerlifters. J Strength Cond Res 32(4): 938-949, 2018-Powerlifters train using specialty bars for unstable load (UL) training. For the bench press, the acute effects of UL are mixed, with few studies that examine training interventions. The purpose of this study was to examine the effects of a 6-week bench press training program that uses the Freak Bar (FB) as compared to a traditional barbell (TB) on maximum bench press, peak force, and peak impulse. Seven men and 3 women (21 ± 2.0 years, 172.2 ± 2.9 cm, and 95.3 ± 20.3 kg) were required to bench press 2 days per week as part of a structured program. On the second bench press day, the FB and TB groups performed 3-position pause bench presses at 60-70% one repetition maximum (1RM). One repetition maximum, peak force, and peak impulse were measured before test and after test after the 6-week program. Peak force and peak impulse were tested at 3 bench positions, including the presticking, sticking, and poststicking points, defined by the distance of the barbell from the chest. Posttraining 1RM for the FB group and TB group increased 6.7% (6.78 ± 1.6 kg, p = 0.006) and 4.3% (4.5 ± 2.7 kg, p = 0.23), respectively, with no significant differences between the groups (p = 0.589, ηp = 0.044). There were no significant differences between the groups at each bench position for peak force (p = 0.606) or peak impulse (p = 0.542). Freak Bar can be an alternative for improving maximum strength and peak force but is not significantly better than TB training when performing the 3-position pause bench press.

Cellular effects of acute exposure to high peak power microwave systems: Morphology and toxicology.

PubMed

Ibey, Bennett L; Roth, Caleb C; Ledwig, Patrick B; Payne, Jason A; Amato, Alayna L; Dalzell, Danielle R; Bernhard, Joshua A; Doroski, Michael W; Mylacraine, Kevin S; Seaman, Ronald L; Nelson, Gregory S; Woods, Clifford W

2016-03-15

Electric fields produced by advanced pulsed microwave transmitter technology now readily exceed the Institute of Electrical and Electronic Engineers (IEEE) C.95.1 peak E-field limit of 100 kV/m, highlighting a need for scientific validation of such a specific limit. Toward this goal, we exposed Jurkat Clone E-6 human lymphocyte preparations to 20 high peak power microwave (HPPM) pulses (120 ns duration) with a mean peak amplitude of 2.3 MV/m and standard deviation of 0.1 with the electric field at cells predicted to range from 0.46 to 2.7 MV/m, well in excess of current standard limit. We observed that membrane integrity and cell morphology remained unchanged 4 h after exposure and cell survival 24 h after exposure was not statistically different from sham exposure or control samples. Using flow cytometry to analyze membrane disruption and morphological changes per exposed cell, no changes were observed in HPPM-exposed samples. Current IEEE C95.1-2005 standards for pulsed radiofrequency exposure limits peak electric field to 100 kV/m for pulses shorter than 100 ms [IEEE (1995) PC95.1-Standard for Safety Levels with Respect to Human Exposure to Electric, Magnetic and Electromagnetic Fields, 0 Hz to 300 GHz, Institute of Electrical and Electronic Engineers: Piscataway, NJ, USA]. This may impose large exclusion zones that limit HPPM technology use. In this study, we offer evidence that maximum permissible exposure of 100 kV/m for peak electric field may be unnecessarily restrictive for HPPM devices. Bioelectromagnetics. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Reproduction of the giant jellyfish, Nemopilema nomurai (Scyphozoa: Rhizostomeae), in 2006-2008 as peripherally-transported populations

NASA Astrophysics Data System (ADS)

Iguchi, Naoki; Lee, Hye Eun; Yoon, Won Duk; Kim, Suam

2010-06-01

This study investigated the sexual maturation process, release of spermatozoa or eggs and oocyte diameter of the rhizostomid medusae Nemopilema nomurai using samples collected from August 2006 to June 2008 from the waters around Korea and Japan, including peripheral areas outside the species’ usual habitat. Immature medusae were observed from June to October only in the western sector of the study area. The onset of spermatozoa and egg release occurred in September and October, respectively, and peaked in December and January. Medusae migrated eastward from source areas with the Tsushima Warm Current, where they formed gametes and spawned. Peak position and maximum oocyte diameter increased as the gonads developed according to the size-frequency distribution of oocytes. No fertilized eggs or embryos were found in the gonads. The correlation was analyzed with bell diameter, maximum oocyte diameter, sampling date, surface water temperature and gonad color to estimate which environmental factors and maturation indices were related to the maturation stage of females. Maturation stage correlated well with maximum oocyte diameter, which correlated negatively with surface water temperature. There was no significant correlation between bell diameter and maturation stage. Therefore, bell diameter was inappropriate for determining maturation index. Sex could not be distinguished clearly by gonad color. However, light pink gonads were more prevalent in males and various deep colors such as orange and brown were more frequent in female medusae.

Total peak shape analysis: detection and quantitation of concurrent fronting, tailing, and their effect on asymmetry measurements.

PubMed

Wahab, M Farooq; Patel, Darshan C; Armstrong, Daniel W

2017-08-04

Most peak shapes obtained in separation science depart from linearity for various reasons such as thermodynamic, kinetic, or flow based effects. An indication of the nature of asymmetry often helps in problem solving e.g. in column overloading, slurry packing, buffer mismatch, and extra-column band broadening. However, existing tests for symmetry/asymmetry only indicate the skewness in excess (tail or front) and not the presence of both. Two simple graphical approaches are presented to analyze peak shapes typically observed in gas, liquid, and supercritical fluid chromatography as well as capillary electrophoresis. The derivative test relies on the symmetry of the inflection points and the maximum and minimum values of the derivative. The Gaussian test is a constrained curve fitting approach and determines the residuals. The residual pattern graphically allows the user to assess the problematic regions in a given peak, e.g., concurrent tailing or fronting, something which cannot be easily done with other current methods. The template provided in MS Excel automates this process. The total peak shape analysis extracts the peak parameters from the upper sections (>80% height) of the peak rather than the half height as is done conventionally. A number of situations are presented and the utility of this approach in solving practical problems is demonstrated. Copyright © 2017 Elsevier B.V. All rights reserved.

Improving peak detection in high-resolution LC/MS metabolomics data using preexisting knowledge and machine learning approach.

PubMed

Yu, Tianwei; Jones, Dean P

2014-10-15

Peak detection is a key step in the preprocessing of untargeted metabolomics data generated from high-resolution liquid chromatography-mass spectrometry (LC/MS). The common practice is to use filters with predetermined parameters to select peaks in the LC/MS profile. This rigid approach can cause suboptimal performance when the choice of peak model and parameters do not suit the data characteristics. Here we present a method that learns directly from various data features of the extracted ion chromatograms (EICs) to differentiate between true peak regions from noise regions in the LC/MS profile. It utilizes the knowledge of known metabolites, as well as robust machine learning approaches. Unlike currently available methods, this new approach does not assume a parametric peak shape model and allows maximum flexibility. We demonstrate the superiority of the new approach using real data. Because matching to known metabolites entails uncertainties and cannot be considered a gold standard, we also developed a probabilistic receiver-operating characteristic (pROC) approach that can incorporate uncertainties. The new peak detection approach is implemented as part of the apLCMS package available at http://web1.sph.emory.edu/apLCMS/ CONTACT: tyu8@emory.edu Supplementary data are available at Bioinformatics online. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Non-censored rib fracture data during frontal PMHS sled tests.

PubMed

Kemper, Andrew R; Beeman, Stephanie M; Porta, David J; Duma, Stefan M

2016-09-01

The purpose of this study was to obtain non-censored rib fracture data due to three-point belt loading during dynamic frontal post-mortem human surrogate (PMHS) sled tests. The PMHS responses were then compared to matched tests performed using the Hybrid-III 50(th) percentile male ATD. Matched dynamic frontal sled tests were performed on two male PMHSs, which were approximately 50(th) percentile height and weight, and the Hybrid-III 50(th) percentile male ATD. The sled pulse was designed to match the vehicle acceleration of a standard sedan during a FMVSS-208 40 kph test. Each subject was restrained with a 4 kN load limiting, driver-side, three-point seatbelt. A 59-channel chestband, aligned at the nipple line, was used to quantify the chest contour, anterior-posterior sternum deflection, and maximum anterior-posterior chest deflection for all test subjects. The internal sternum deflection of the ATD was quantified with the sternum potentiometer. For the PMHS tests, a total of 23 single-axis strain gages were attached to the bony structures of the thorax, including the ribs, sternum, and clavicle. In order to create a non-censored data set, the time history of each strain gage was analyzed to determine the timing of each rib fracture and corresponding timing of each AIS level (AIS = 1, 2, 3, etc.) with respect to chest deflection. Peak sternum deflection for PMHS 1 and PMHS 2 were 48.7 mm (19.0%) and 36.7 mm (12.2%), respectively. The peak sternum deflection for the ATD was 20.8 mm when measured by the chest potentiometer and 34.4 mm (12.0%) when measured by the chestband. Although the measured ATD sternum deflections were found to be well below the current thoracic injury criterion (63 mm) specified for the ATD in FMVSS-208, both PMHSs sustained AIS 3+ thoracic injuries. For all subjects, the maximum chest deflection measured by the chestband occurred to the right of the sternum and was found to be 83.0 mm (36.0%) for PMHS 1, 60.6 mm (23.9%) for PMHS 2, and 56.3 mm (20.0%) for the ATD. The non-censored rib fracture data in the current study (n = 2 PMHS) in conjunction with the non-censored rib fracture data from two previous table-top studies (n = 4 PMHS) show that AIS 3+ injury timing occurs prior to peak sternum compression, prior to peak maximum chest compression, and at lower compressions than might be suggested by current PMHS thoracic injury criteria developed using censored rib fracture data. In addition, the maximum chest deflection results showed a more reasonable correlation between deflection, rib fracture timing, and injury severity than sternum deflection. Overall, these data provide compelling empirical evidence that suggests a more conservative thoracic injury criterion could potentially be developed based on non-censored rib fracture data with additional testing performed over a wider range of subjects and loading conditions.

Estimation of peak discharge quantiles for selected annual exceedance probabilities in northeastern Illinois

USGS Publications Warehouse

Over, Thomas M.; Saito, Riki J.; Veilleux, Andrea G.; Sharpe, Jennifer B.; Soong, David T.; Ishii, Audrey L.

2016-06-28

This report provides two sets of equations for estimating peak discharge quantiles at annual exceedance probabilities (AEPs) of 0.50, 0.20, 0.10, 0.04, 0.02, 0.01, 0.005, and 0.002 (recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years, respectively) for watersheds in Illinois based on annual maximum peak discharge data from 117 watersheds in and near northeastern Illinois. One set of equations was developed through a temporal analysis with a two-step least squares-quantile regression technique that measures the average effect of changes in the urbanization of the watersheds used in the study. The resulting equations can be used to adjust rural peak discharge quantiles for the effect of urbanization, and in this study the equations also were used to adjust the annual maximum peak discharges from the study watersheds to 2010 urbanization conditions.The other set of equations was developed by a spatial analysis. This analysis used generalized least-squares regression to fit the peak discharge quantiles computed from the urbanization-adjusted annual maximum peak discharges from the study watersheds to drainage-basin characteristics. The peak discharge quantiles were computed by using the Expected Moments Algorithm following the removal of potentially influential low floods defined by a multiple Grubbs-Beck test. To improve the quantile estimates, regional skew coefficients were obtained from a newly developed regional skew model in which the skew increases with the urbanized land use fraction. The drainage-basin characteristics used as explanatory variables in the spatial analysis include drainage area, the fraction of developed land, the fraction of land with poorly drained soils or likely water, and the basin slope estimated as the ratio of the basin relief to basin perimeter.This report also provides the following: (1) examples to illustrate the use of the spatial and urbanization-adjustment equations for estimating peak discharge quantiles at ungaged sites and to improve flood-quantile estimates at and near a gaged site; (2) the urbanization-adjusted annual maximum peak discharges and peak discharge quantile estimates at streamgages from 181 watersheds including the 117 study watersheds and 64 additional watersheds in the study region that were originally considered for use in the study but later deemed to be redundant.The urbanization-adjustment equations, spatial regression equations, and peak discharge quantile estimates developed in this study will be made available in the web application StreamStats, which provides automated regression-equation solutions for user-selected stream locations. Figures and tables comparing the observed and urbanization-adjusted annual maximum peak discharge records by streamgage are provided at https://doi.org/10.3133/sir20165050 for download.

Stature and body weight growth during adolescence based on longitudinal data of Japanese children born during World War II.

PubMed

Ashizawa, K; Takahashi, C; Yanagisawa, S

1978-09-01

Longitudinal survey data of stature and body weight from age 7 to 17 were obtained for 100 boys and 100 girls during World War II. The growth rates and the average annual increments were compared with those of children born after the war. Growth attained at age 7 as a percentage of that at age 17 is larger in children of the control group, presumably as a result of an improved environment affecting the growth increment. The age at maximum velocity is six months to one year earlier for the current group of children. Although the maximum velocities for both items and sexes are nearly the same in the groups compared, the total increments are larger in the current group of children. Age, distance, and maximum velocity at adolescent growth spurt were obtained for each child. The mean values were compared according to growth patterns and growth attained at age 7. The "increasing type" growth group has the highest velocity at the greatest distance and the oldest age for stature. Children who were taller or heavier at age 7 have velocity peaks with greater distances.

Carbon nanotube wires with continuous current rating exceeding 20 Amperes

NASA Astrophysics Data System (ADS)

Cress, Cory D.; Ganter, Matthew J.; Schauerman, Christopher M.; Soule, Karen; Rossi, Jamie E.; Lawlor, Colleen C.; Puchades, Ivan; Ubnoske, Stephen M.; Bucossi, Andrew R.; Landi, Brian J.

2017-07-01

A process to fabricate carbon nanotube (CNT) wires with diameters greater than 1 cm and continuous current carrying capability exceeding 20 A is demonstrated. Wires larger than 5 mm are formed using a multi-step radial densification process that begins with a densified CNT wire core followed by successive wrapping of additional CNT material to increase the wire size. This process allows for a wide range of wire diameters to be fabricated, with and without potassium tetrabromoaurate (KAuBr4) chemical doping, and the resulting electrical and thermal properties to be characterized. Electrical measurements are performed with on/off current steps to obtain the maximum current before reaching a peak CNT wire temperature of 100 °C and before failure, yielding values of instantaneous currents in excess of 45 A for KAuBr4 doped CNT wires with a diameter of 6 mm achieved prior to failure. The peak temperature of the wires at failure (˜530 °C) is correlated with the primary decomposition peak observed in thermal gravimetric analysis of a wire sample confirming that oxidation is the primary failure mode of CNT wires operated in air. The in operando stability of doped CNT wires is confirmed by monitoring the resistance and temperature, which remain largely unaltered over 40 days and 1 day for wires with 1.5 mm and 11.2 mm diameters, respectively. The 100 °C continuous current rating, or ampacity, is measured for a range of doped CNT wire diameters and corresponding linear mass densities ρL. To describe the results, a new form of the fuse-law, where the critical current is defined as I ∝ρL3 /4, is developed and shows good agreement with the experimental data. Ultimately, CNT wires are shown to be stable electrical conductors, with failure current densities in excess of 50 A in the case of a convectively cooled 11.2 mm doped CNT wire, and amenable for use in applications that have long-term, high-current demands.

Photoemission experiments of a large area scandate dispenser cathode

NASA Astrophysics Data System (ADS)

Zhang, Huang; Liu, Xing-guang; Chen, Yi; Chen, De-biao; Jiang, Xiao-guo; Yang, An-min; Xia, Lian-sheng; Zhang, Kai-zhi; Shi, Jin-shui; Zhang, Lin-wen

2010-09-01

A 100-mm-diameter scandate dispenser cathode was tested as a photocathode with a 10 ns Nd:YAG laser (266 nm) on an injector test stand for linear induction accelerators. This thermionic dispenser cathode worked at temperatures ranging from room temperature to 930 °C (below or near the thermionic emission threshold) while the vacuum was better than 4×10 -7 Torr. The laser pulse was synchronized with a 120 ns diode voltage pulse stably and they were in single pulse mode. Emission currents were measured by a Faraday cup. The maximum peak current collected at the anode was about 100 A. The maximum quantum efficiency measured at low laser power was 2.4×10 -4. Poisoning effect due to residual gas was obvious and uninterrupted heating was needed to keep cathode's emission capability. The cathode was exposed to air one time between experiments and recovered after being reconditioned. Photoemission uniformity of the cathode was also explored by changing the laser spot's position.

Rip Current Velocity Structure in Drifter Trajectories and Numerical Simulations

NASA Astrophysics Data System (ADS)

Schmidt, W. E.; Slinn, D. N.

2008-12-01

Estimates of rip current velocity and cross-shore structure were made using surfzone drifters, bathymetric surveys, and rectified video images. Over 60 rip current trajectories were observed during a three year period at a Southern California beach in July 2000, 2001, and 2002. Incident wave heights (Hs) immediately offshore (~7 m depth) were obtained by initializing a refraction model with data from nearby directional wave buoys, and varied from 0.3 to 1.0 m. Tide levels varied over approximately 1 m and winds were light. Numerical simulations using the non-linear shallow water equations and modeled over measured bathymetry also produced similar flows and statistics. Time series of drifter position, sampled at 1 Hz, were first-differenced to produce velocity time series. Maximum observed velocities varied between 25 and 80 cm s-1, whereas model maximum velocities were lower by a factor 2 to 3. When velocity maxima were non-dimensionalized by respective trajectory mean velocity, both observed and modeled values varied between 1.5 and 3.5. Cross-shore location of rip current velocity maxima for both shore-normal and shore-oblique rip currents were strongly coincident with the surfzone edge (Xb), as determined by rectified video (observations) or breakpoint (model). Once outside of the surfzone, observed and modeled rip current velocities decreased to 10% of their peak values within 2 surfzone widths of the shoreline, a useful definition of rip current cross-shore extent.

Runners with Patellofemoral Pain Exhibit Greater Peak Patella Cartilage Stress Compared to Pain-Free Runners.

PubMed

Liao, Tzu-Chieh; Keyak, Joyce H; Powers, Christopher M

2018-02-27

The purpose of this study is to determine whether recreational runners with patellofemoral pain (PFP) exhibit greater peak patella cartilage stress compared to pain-free runners. A secondary purpose was to determine the kinematic and/or kinetic predictors of peak patella cartilage stress during running. Twenty-two female recreational runners participated (12 with PFP and 10 pain-free controls). Patella cartilage stress profiles were quantified using subject-specific finite element models simulating the maximum knee flexion angle during stance phase of running. Input parameters to the finite element model included subject-specific patellofemoral joint geometry, quadriceps muscle forces, and lower extremity kinematics in the frontal and transverse planes. Tibiofemoral joint kinematics and kinetics were quantified to determine the best predictor of stress using stepwise regression analysis. Compared to the pain-free runners, those with PFP exhibited greater peak hydrostatic pressure (PFP vs. control, 21.2 ± 5.6 MPa vs. 16.5 ± 4.6 MPa) and maximum shear stress (11.3 ± 4.6 MPa vs. 8.7 ± 2.3 MPa). Knee external rotation was the best predictor of peak hydrostatic pressure and peak maximum shear stress (38% and 25% of variances, respectively) followed by the knee extensor moment (21% and 25% of variances, respectively). Runners with PFP exhibit greater peak patella cartilage stress during running compared to pain-free individuals. The combination of knee external rotation and a high knee extensor moment best predicted elevated peak stress during running.

Low frequency spectra of type III solar radio bursts

NASA Technical Reports Server (NTRS)

Weber, R. R.

1978-01-01

Flux density spectra have been determined for 91 simple type III solar bursts observed by the Goddard Space Flight Center radio astronomy experiment on the IMP-6 spacecraft during 1971 and 1972. Spectral peaks were found to occur at frequencies ranging from 44 kHz up to 2500 kHz. Half of the bursts peaked between 250 kHz and 900 kHz, corresponding to emission at solar distances of about 0.3 to 0.1 AU. Maximum burst flux density sometimes exceeds 10 to the -14th W/sq m/Hz. The primary factor controlling the spectral peak frequency of these bursts appears to be a variation in intrinsic power radiated by the source as the exciter moves outward from the sun, rather than radio propagation effects between the source and IMP-6. Thus, a burst spectrum strongly reflects the evolution of the properties of the exciting electron beam, and according to current theory, beam deceleration could help account for the observations.

A thermal/nonthermal model for solar microwave bursts

NASA Technical Reports Server (NTRS)

Benka, Stephen G.; Holman, Gordon D.

1992-01-01

A theoretical framework is developed for modeling high-resolution spectra of microwave bursts from the Owens Valley Radio Observatory which can account for departures from expectations based on simple thermal or nonthermal models. Specifically, 80 percent of the events show more than one spectral peak; many bursts have a low-side spectral index steeper than the maximum expected slope; and the peak frequency stays relatively constant and changes intensity in concert with the secondary peaks throughout a given event's solution. It is shown that the observed spectral features can be explained through gyrosynchrotron radiation. The 'secondary' components seen on the LF side of many spectra are nonthermal enhancements superposed upon thermal radiation, occurring between the thermal harmonics. A steep optically thick slope is accounted for by the thermal absorption of nonthermal radiation. If the coexistence of thermal and nonthermal particles is interpreted in terms of electron heating and acceleration in current sheets, a changing electric field strength can account for the gross evolution of the microwave spectra.

Numerical modelling of organic waste dispersion from fjord located fish farms

NASA Astrophysics Data System (ADS)

Ali, Alfatih; Thiem, Øyvind; Berntsen, Jarle

2011-07-01

In this study, a three-dimensional particle tracking model coupled to a terrain following ocean model is used to investigate the dispersion and the deposition of fish farm particulate matter (uneaten food and fish faeces) on the seabed due to tidal currents. The particle tracking model uses the computed local flow field for advection of the particles and random movement to simulate the turbulent diffusion. Each particle is given a settling velocity which may be drawn from a probability distribution according to settling velocity measurements of faecal and feed pellets. The results show that the maximum concentration of organic waste for fast sinking particles is found under the fish cage and continue monotonically decreasing away from the cage area. The maximum can split into two maximum peaks located at both sides of the centre of the fish cage area in the current direction. This process depends on the sinking time (time needed for a particle to settle at the bottom), the tidal velocity and the fish cage size. If the sinking time is close to a multiple of the tidal period, the maximum concentration point will be under the fish cage irrespective of the tide strength. This is due to the nature of the tidal current first propagating the particles away and then bringing them back when the tide reverses. Increasing the cage size increases the likelihood for a maximum waste accumulation beneath the fish farm, and larger farms usually means larger biomasses which can make the local pollution even more severe. The model is validated by using an analytical model which uses an exact harmonic representation of the tidal current, and the results show an excellent agreement. This study shows that the coupled ocean and particle model can be used in more realistic applications to help estimating the local environmental impact due to fish farms.

Fast switching thyristor applied in nanosecond-pulse high-voltage generator with closed transformer core.

PubMed

Li, Lee; Bao, Chaobing; Feng, Xibo; Liu, Yunlong; Fochan, Lin

2013-02-01

For a compact and reliable nanosecond-pulse high-voltage generator (NPHVG), the specification parameter selection and potential usage of fast controllable state-solid switches have an important bearing on the optimal design. The NPHVG with closed transformer core and fast switching thyristor (FST) was studied in this paper. According to the analysis of T-type circuit, the expressions for the voltages and currents of the primary and secondary windings on the transformer core of NPHVG were deduced, and the theoretical maximum analysis was performed. For NPHVG, the rise-rate of turn-on current (di/dt) across a FST may exceed its transient rating. Both mean and maximum values of di/dt were determined by the leakage inductances of the transformer, and the difference is 1.57 times. The optimum winding ratio is helpful to getting higher voltage output with lower specification FST, especially when the primary and secondary capacitances have been established. The oscillation period analysis can be effectively used to estimate the equivalent leakage inductance. When the core saturation effect was considered, the maximum di/dt estimated from the oscillating period of the primary current is more accurate than one from the oscillating period of the secondary voltage. Although increasing the leakage inductance of NPHVG can decrease di/dt across FST, it may reduce the output peak voltage of the NPHVG.

A Systematic Review of Isometric Lingual Strength-Training Programs in Adults With and Without Dysphagia.

PubMed

McKenna, Victoria S; Zhang, Bin; Haines, Morgan B; Kelchner, Lisa N

2017-05-17

This systematic review summarizes the effects of isometric lingual strength training on lingual strength and swallow function in adult populations. Furthermore, it evaluates the designs of the reviewed studies and identifies areas of future research in isometric lingual strength training for dysphagia remediation. A comprehensive literature search of 3 databases and additional backward citation search identified 10 studies for inclusion in the review. The review reports and discusses the isometric-exercise intervention protocols, pre- and postintervention lingual-pressure data (maximum peak pressures and lingual-palatal pressures during swallowing), and oropharyngeal swallowing measures such as penetration-aspiration scales, oropharyngeal residue and duration, lingual volumes, and quality-of-life assessments. Studies reported gains in maximum peak lingual pressures following isometric lingual strength training for both healthy adults and select groups of individuals with dysphagia. However, due to the variability in study designs, it remains unclear whether strength gains generalize to swallow function. Although isometric lingual strength training is a promising intervention for oropharyngeal dysphagia, the current literature is too variable to confidently report specific therapeutic benefits. Future investigations should target homogenous patient populations and use randomized controlled trials to determine the efficacy of this treatment for individuals with dysphagia.

Optimizing integrated luminosity of future hadron colliders

NASA Astrophysics Data System (ADS)

Benedikt, Michael; Schulte, Daniel; Zimmermann, Frank

2015-10-01

The integrated luminosity, a key figure of merit for any particle-physics collider, is closely linked to the peak luminosity and to the beam lifetime. The instantaneous peak luminosity of a collider is constrained by a number of boundary conditions, such as the available beam current, the maximum beam-beam tune shift with acceptable beam stability and reasonable luminosity lifetime (i.e., the empirical "beam-beam limit"), or the event pileup in the physics detectors. The beam lifetime at high-luminosity hadron colliders is largely determined by particle burn off in the collisions. In future highest-energy circular colliders synchrotron radiation provides a natural damping mechanism, which can be exploited for maximizing the integrated luminosity. In this article, we derive analytical expressions describing the optimized integrated luminosity, the corresponding optimum store length, and the time evolution of relevant beam parameters, without or with radiation damping, while respecting a fixed maximum value for the total beam-beam tune shift or for the event pileup in the detector. Our results are illustrated by examples for the proton-proton luminosity of the existing Large Hadron Collider (LHC) at its design parameters, of the High-Luminosity Large Hadron Collider (HL-LHC), and of the Future Circular Collider (FCC-hh).

Variability of Surface pollutants and aerosol concentration over Abu Dhabi, UAE - sources, transport and current levels

NASA Astrophysics Data System (ADS)

Phanikumar, Devulapalli V.; Basha, Ghouse; Ouarda, Taha B. M. J.

2015-04-01

In the view of recent economic, industrial, and rapid development, Abu Dhabi (24.4oN; 54.4oE; 27m msl) has become one of the most populated regions in the world despite of extreme heat, frequent dust storms, and with distinctive topography. The major sources of air pollution are from the dust and sand storms, greenhouse gas emissions, and to some extent from industrial pollution. In order to realize the accurate and comprehensive understanding of air quality and plausible sources over this region, we have made a detailed analysis of three years simultaneous measurements during 2011-13 of pollutants such as O3, SO2, NO2, CO, and PM10 concentrations. Diurnal variation of meteorological parameters such as temperature and wind speed/relative humidity clearly shows daytime maximum/minimum in summer followed by pre-monsoon, post-monsoon and winter. The prevailing winds over this region are mostly from northwesterly direction (Shamal wind). Diurnal wind pattern showed a clear contrast with the majority of the wind pattern during nighttime and early morning is from the westerly/northwesterly and daytime is from southwesterly/southeasterly directions. The diurnal pattern of O3 shows minimum during 08 LT and increases thereafter reaching maximum at 17 LT and decreases during nighttime. However, the diurnal pattern of SO2 and NO2 show a peak at ~ 08 LT and dip at ~ 14 LT during all the seasons with some variability in each season. On the other hand, the diurnal pattern of CO shows a peculiar picture of elevated levels during daytime peaking at ~ 10 LT (prominent in summer and post-monsoon) followed by a sharp decrease and minimum is ~14 LT. PM10 concentration has an early morning peak at ~ 02 LT and then decreases to a minimum value at ~11 LT and again increases in the afternoon hours (maximum at ~17 LT) depicting a forenoon-afternoon asymmetry. Monthly variation of PM10 shows maximum in pre-monsoon season and minimum in winter. Our observations show the diurnal pattern of pollutants are in contrast with the diurnal pattern of wind speed as evident from the previous observations. Wind rose diagram of pollutants reveal that the dominant source directions are scattered from northwesterly to southwesterly. Our results (2011-13) are compared with earlier observations from the same region (2007-08) and no alarming differences were observed in the pollutant levels. Our observations are discussed in the light of current understanding of pollutants sources over this region.

The Effect of the Ionosphere on Radiowave Signals and Systems Performance Based on Ionospheric Effects Symposium Held on 1-3 May 1990

DTIC Science & Technology

1990-05-03

winter and a minimum in summer ; in contrast, at sunspot maximum the seasonal peaks tend to occur around the equinoxes and the minima in summer . ’riis is...more clearly seen in Figures 4(b) ahnd 4(c). Note that around sunspot maximum the summer noon value may be less than the summer midnight value. (3) The...seasonal variation of the midnight values show summer peaks and winter minima with high values near the peaks of the sunspot cycles and low values

Positive inotropic effects of RP 62719, a new pure class III antiarrhythmic agent, on guinea pig myocardium.

PubMed

Beregi, J P; Escande, D; Coudray, N; Mery, P; Mestre, M; Chemla, D; Lecarpentier, Y

1992-12-01

The mechanical effects of RP 62719 [(-)1-[-2-(3,4-dihydro-2H-1- benzopyran-4-yl)ethyl]-4-(3,4-dimethoxyphenyl)-piperidine] were tested in vitro on guinea pig left ventricular papillary muscle. RP 62719 is a novel pure class III antiarrhythmic agent known to prolong the cardiac action potential duration by selectively blocking the inward rectifying K+ current. Mechanical parameters were determined from contraction and relaxation phases under isotonic and isometric conditions. At a concentration of 0.02 microM, RP 62719 did not produce significant effects on inotropy or lusitropy. At 0.2 and 2 microM, the drug improved contraction under both heavy and low loading conditions, as evidenced by a 30% increase in maximum unloaded shortening velocity (Vmax, P < .001), peak amplitude of shortening (delta L, P < .001), peak isometric active force normalized per cross-sectional area (AF/s, P < .001) and positive peak of the force derivative per mm2 (+dF/s, P < .001). At the same concentrations, positive lusitropic effects were evidenced by an increase in maximum lengthening velocity (maxVr) and negative peak of force derivative per mm2 (-dF/s, P < .001). At a higher concentration (20 microM), effects of RP 62719 on inotropy and lusitropy were less marked, thus accounting for the bell-shaped form of the dose-response curve. An increase in the extracellular Ca++ concentration from 2.5 to 3.75 mM improved inotropy to a similar extent (+30-50%) as did 2 microM RP 62719. However, lusitropy and mechanical coupling between contraction and relaxation were not modified in the same proportion under RP 62719 and under 3.75 mM Ca++.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro effects of recombinant activated factor VII on thrombin generation and coagulation following inhibition of platelet procoagulant activity by prasugrel.

PubMed

Mazzeffi, Michael; Szlam, Fania; Jakubowski, Joseph A; Tanaka, Kenichi A; Sugidachi, Atsuhiro; Levy, Jerrold H

2013-07-01

Prasugrel is a thienopyridyl P2Y12 antagonist with potent antiplatelet effects. At present, little is known about its effects on thrombin generation or what strategies may emergently reverse its anticoagulant effects. In the current study we evaluated whether recombinant activated factor VII may reverse prasugrel induced effects and increase thrombin generation in an in vitro model. The effect of prasugrel active metabolite, PAM (R-138727), was evaluated on platelet aggregation, thrombin generation, and rotational thromboelastometry parameters using blood from 20 healthy volunteers. Additionally, we evaluated the effects of adenosine diphosphate (ADP) and recombinant activated factor VII on restoring these parameters towards baseline values. PAM reduced maximum platelet aggregation and led to platelet disaggregation. It also decreased peak thrombin, increased lag time, and increased time to peak thrombin. Treatment with recombinant activated factor VII restored all three parameters of thrombin generation towards baseline. ADP decreased lag time and time to peak thrombin, but had no effect on peak thrombin. When recombinant activated factor VII and ADP were combined they had a greater effect on thrombin parameters than either drug alone. PAM also increased thromboelastometric clotting time and clot formation time, but had no effect on maximum clot firmness. Treatment with either recombinant activated factor VII or ADP restored these values towards baseline. Recombinant activated factor VII restores thrombin generation in the presence of PAM. In patients taking prasugrel with life-threatening refractory bleeding it has the potential to be a useful therapeutic approach. Additional clinical studies are needed to validate our findings. Copyright © 2013 Elsevier Ltd. All rights reserved.

Application of high-quality SiO2 grown by multipolar ECR source to Si/SiGe MISFET

NASA Technical Reports Server (NTRS)

Sung, K. T.; Li, W. Q.; Li, S. H.; Pang, S. W.; Bhattacharya, P. K.

1993-01-01

A 5 nm-thick SiO2 gate was grown on an Si(p+)/Si(0.8)Ge(0.2) modulation-doped heterostructure at 26 C with an oxygen plasma generated by a multipolar electron cyclotron resonance source. The ultrathin oxide has breakdown field above 12 MV/cm and fixed charge density about 3 x 10 exp 10/sq cm. Leakage current as low as 1/micro-A was obtained with the gate biased at 4 V. The MISFET with 0.25 x 25 sq m gate shows maximum drain current of 41.6 mA/mm and peak transconductance of 21 mS/mm.

Bridge-scour analysis on Cuchillo Negro Creek at the Interstate 25 crossing near Truth or Consequences, New Mexico

USGS Publications Warehouse

Waltemeyer, S.D.

1995-01-01

A sediment-transport model to simulate channel change was applied to a 1-mile reach of Cuchillo Negro Creek at the Interstate 25 crossing at Truth or Consequences, New Mexico, using the Bridge-Stream Tube model for Alluvial River Simulation (BRI-STARS). The 500-year flood discharge was estimated to be 10,700 cubic feet per second. The 100-year, 500-year, and regional maximum discharges were used to design synthetic and discretized hydrographs using a flood volume equation. The regional maximum discharge relation was developed for New Mexico based on 259 streamflow-gaging stations' maximum peak discharge. The regional maximum-peak discharge for the site was determined to be 81,700 cubic feet per second. Bed-material particle-size distribution was determined for six size classes ranging from 1 to 30 millimeters. The median diameter was 4.6 millimeters at the bed surface and 9.0 millimeters 13 feet below the bed surface. Bed-material discharge for use in the model was estimated to be 18,770 tons per day using hydraulic properties, water temperature, and Yang's gravel equation. Channel-change simulations showed a maximum channel degradation of 1.38 feet for the regional maximum-peak discharge hydrograph.

A Study of the Response of the Human Cadaver Head to Impact

PubMed Central

Hardy, Warren N.; Mason, Matthew J.; Foster, Craig D.; Shah, Chirag S.; Kopacz, James M.; Yang, King H.; King, Albert I.; Bishop, Jennifer; Bey, Michael; Anderst, William; Tashman, Scott

2008-01-01

High-speed biplane x-ray and neutral density targets were used to examine brain displacement and deformation during impact. Relative motion, maximum principal strain, maximum shear strain, and intracranial pressure were measured in thirty-five impacts using eight human cadaver head and neck specimens. The effect of a helmet was evaluated. During impact, local brain tissue tends to keep its position and shape with respect to the inertial frame, resulting in relative motion between the brain and skull and deformation of the brain. The local brain motions tend to follow looping patterns. Similar patterns are observed for impact in different planes, with some degree of posterior-anterior and right-left symmetry. Peak coup pressure and pressure rate increase with increasing linear acceleration, but coup pressure pulse duration decreases. Peak average maximum principal strain and maximum shear are on the order of 0.09 for CFC 60 Hz data for these tests. Peak average maximum principal strain and maximum shear increase with increasing linear acceleration, coup pressure, and coup pressure rate. Linear and angular acceleration of the head are reduced with use of a helmet, but strain increases. These results can be used for the validation of finite element models of the human head. PMID:18278591

Climate Change Impacts on Peak Electricity Consumption: US vs. Europe.

NASA Astrophysics Data System (ADS)

Auffhammer, M.

2016-12-01

It has been suggested that climate change impacts on the electric sector will account for the majority of global economic damages by the end of the current century and beyond. This finding is at odds with the relatively modest increase in climate driven impacts on consumption. Comprehensive high frequency load balancing authority level data have not been used previously to parameterize the relationship between electric demand and temperature for any major economy. Using statistical models we analyze multi-year data from load balancing authorities in the United States of America and the European Union, which are responsible for more than 90% of the electricity delivered to residential, industrial, commercial and agricultural customers. We couple the estimated response functions between total daily consumption and daily peak load with an ensemble of downscaled GCMs from the CMIP5 archive to simulate climate change driven impacts on both outcomes. We show moderate and highly spatially heterogeneous changes in consumption. The results of our peak load simulations, however, suggest significant changes in the intensity and frequency of peak events throughout the United States and Europe. As the electricity grid is built to endure maximum load, which usually occurs on the hottest day of the year, our findings have significant implications for the construction of costly peak generating and transmission capacity.

Inlet Flow Characteristics During Rapid Maneuvers for an F/A-18A Airplane

NASA Technical Reports Server (NTRS)

Steenken, William G.; Williams, John G.; Walsh, Kevin R.

1999-01-01

The F404-GE-400 engine powered F/A-18A High Alpha Research Vehicle (HARV) was used to examine the characteristics of inlet airflow during rapid aircraft maneuvers. A study of the degree of similarity between inlet data obtained during rapid aircraft maneuvers and inlet data obtained at steady aerodynamic attitudes was conducted at the maximum engine airflow of approximately 145 Ibm/sec using a computer model that was generated from inlet data obtained during steady aerodynamic maneuvers. Results show that rapid-maneuver inlet recoveries agreed very well with the recoveries obtained at equivalent stabilized angle-of-attack conditions. The peak dynamic circumferential distortion values obtained during rapid maneuvers agreed within 0.01 units of distortion over the 10 - 38 degree angle of attack range with the values obtained during steady aerodynamic maneuvers while similar agreement was found for the peak dynamic radial distortion values up to 29 degrees angle-of-attack. Exceedences of the rapid-maneuver peak dynamic circumferential distortion values relative to the peak distortion model values at steady attitudes occurred only at low or negative angles of attack and were inconsequential from an engine-stability assessment point of view. The results of this study validate the current industry practice of testing at steady aerodynamic conditions to characterize inlet recovery and peak dynamic distortion levels.

Top-Off Injection and Higher Currents at the Stanford Synchrotron Radiation Lightsource

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

Bauer, Johannes M.; Liu, James C.; Prinz, Alyssa A.

2011-04-05

The Stanford Synchrotron Radiation Lightsource (SSRL) at the SLAC National Accelerator Laboratory is a 234 m circumference storage ring for 3 GeV electrons with its synchrotron radiation serving currently 13 beamlines with about 27 experimental stations. It operated for long time with 100 mA peak current provided by usually three injections per day. In July 2009, the maximum beam current was raised to 200 mA. Over the period from June 2009 to March 2010, Top-Off operation started at every beamline. Top-Off, i.e., the injection of electrons into the storage ring with injection stoppers open, is necessary for SSRL to reachmore » its design current of 500 mA. In the future, the maximal power of the injection current will also soon be raised from currently 1.5 W to 5 W. The Radiation Protection Department at SLAC worked with SSRL on the specifications for the safety systems for operation with Top-Off injection and higher beam currents.« less

ZnS-Based ZnSTe:N/n-ZnS Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Ichino, Kunio; Kojima, Takahiro; Obata, Shunsuke; Kuroyanagi, Takuma; Nakazawa, Shoichi; Kashiyama, Shota

2013-11-01

ZnS1-xTex:N/n-ZnS diodes have been fabricated in an attempt to convert ZnS into p-type by Te incorporation and the resulting upward shift of the valence band maximum. The diodes exhibit clear rectification in the current-voltage characteristic and a peak of the electron-beam-induced current at the ZnS1-xTex:N/n-ZnS interface. Furthermore, a ZnS0.85Te0.15:N/n-ZnS diode exhibits blue-green electroluminescence due to self-activated emission in n-ZnS at 290 K under a forward current. These results suggest p-type conduction in ZnS1-xTex:N, and thus the LED operation of a ZnS-based pn-junction.

Power Generation Evaluated on a Bismuth Telluride Unicouple Module

NASA Astrophysics Data System (ADS)

Hu, Xiaokai; Nagase, Kazuo; Jood, Priyanka; Ohta, Michihiro; Yamamoto, Atsushi

2015-06-01

The power generated by a thermoelectric unicouple module made of Bi2Te3 alloy was evaluated by use of a newly developed instrument. An electrical load was connected to the module, and the terminal voltage and output power of the module were obtained by altering electric current. Water flow was used to cool the cold side of the module and for heat flow measurement, by monitoring inlet and outlet temperatures. When the electric current was increased, heat flow was enhanced as a result of the Peltier effect and Joule heating. Voltage, power, heat flow, and efficiency as functions of current were determined for hot-side temperatures from 50 to 220°C. Maximum power output and peak conversion efficiency could thus be easily derived for each temperature.

Pi meson radiotherapy for advanced head and neck neoplasms: preliminary results.

PubMed

Khan, K M; Bush, S; Herzon, F; Klingerman, M M

1981-01-01

Under the auspices of the University of New Mexico Cancer Research and Treatment Center, trials are under way at the Los Alamos Meson Physics Facility to evaluate the effects of pi meson irradiation on locally advanced human tumors. This paper summarizes the preliminary results in patients with locally advanced head and neck tumors treated under Phase 1 and Phase II studies. A total of 26 patients were treated between June 1977 and May 1979 with a minimum follow-up of 9 months and a maximum follow-up of 33 months. Sites of disease included the oropharynx in 10 cases (base of tongue in 7, tonsil in 2, and pharyngoepiglottic fold in 1), the supraglottic larynx in 4, the nasopharynx in 5, the oral cavity in 4, the hypopharynx in 2, and the sublingual salivary gland in 1. Twelve of the 26 patients are alive, and 10 survive with no evidence of disease. Doses employed ranged from a minimum of 1,000 peak pion rad in 7 fractions over 9 days to a maximum of 5,4000 peak pion rad in 51 fractions of 89 days. The minimum dose employed for any patients treated with peak pions alone was 3,000 rad. These data are analyzed according to dose, sit, histology, tumor response, local control, and survival. Results from these cases form the basis of the Phase III randomized trials for advanced squamous-cell carcinomas of the head and neck, which are currently in progress.

Application of the Extreme Value Distribution to Estimate the Uncertainty of Peak Sound Pressure Levels at the Workplace.

PubMed

Lenzuni, Paolo

2015-07-01

The purpose of this article is to develop a method for the statistical inference of the maximum peak sound pressure level and of the associated uncertainty. Both quantities are requested by the EU directive 2003/10/EC for a complete and solid assessment of the noise exposure at the workplace. Based on the characteristics of the sound pressure waveform, it is hypothesized that the distribution of the measured peak sound pressure levels follows the extreme value distribution. The maximum peak level is estimated as the largest member of a finite population following this probability distribution. The associated uncertainty is also discussed, taking into account not only the contribution due to the incomplete sampling but also the contribution due to the finite precision of the instrumentation. The largest of the set of measured peak levels underestimates the maximum peak sound pressure level. The underestimate can be as large as 4 dB if the number of measurements is limited to 3-4, which is common practice in occupational noise assessment. The extended uncertainty is also quite large (~2.5 dB), with a weak dependence on the sampling details. Following the procedure outlined in this article, a reliable comparison between the peak sound pressure levels measured in a workplace and the EU directive action limits is possible. Non-compliance can occur even when the largest of the set of measured peak levels is several dB below such limits. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Induction linear accelerators

NASA Astrophysics Data System (ADS)

Birx, Daniel

1992-03-01

Among the family of particle accelerators, the Induction Linear Accelerator is the best suited for the acceleration of high current electron beams. Because the electromagnetic radiation used to accelerate the electron beam is not stored in the cavities but is supplied by transmission lines during the beam pulse it is possible to utilize very low Q (typically<10) structures and very large beam pipes. This combination increases the beam breakup limited maximum currents to of order kiloamperes. The micropulse lengths of these machines are measured in 10's of nanoseconds and duty factors as high as 10-4 have been achieved. Until recently the major problem with these machines has been associated with the pulse power drive. Beam currents of kiloamperes and accelerating potentials of megavolts require peak power drives of gigawatts since no energy is stored in the structure. The marriage of liner accelerator technology and nonlinear magnetic compressors has produced some unique capabilities. It now appears possible to produce electron beams with average currents measured in amperes, peak currents in kiloamperes and gradients exceeding 1 MeV/meter, with power efficiencies approaching 50%. The nonlinear magnetic compression technology has replaced the spark gap drivers used on earlier accelerators with state-of-the-art all-solid-state SCR commutated compression chains. The reliability of these machines is now approaching 1010 shot MTBF. In the following paper we will briefly review the historical development of induction linear accelerators and then discuss the design considerations.

Magnetic Configurations of the Tilted Current Sheets and Dynamics of Their Flapping in Magnetotail

NASA Astrophysics Data System (ADS)

Shen, C.; Rong, Z. J.; Li, X.; Dunlop, M.; Liu, Z. X.; Malova, H. V.; Lucek, E.; Carr, C.

2009-04-01

Based on multiple spacecraft measurements, the geometrical structures of tilted current sheet and tail flapping waves have been analyzed and some features of the tilted current sheets have been made clear for the first time. The geometrical features of the tilted current sheet revealed in this investigation are as follows: (1) The magnetic field lines (MFLs) are generally plane curves and the osculating planes in which the MFLs lie are about vertical to the magnetic equatorial plane, while the tilted current sheet may lean severely to the dawn or dusk side. (2) The tilted current sheet may become very thin, its half thickness is generally much less than the minimum radius of the curvature of the MFLs. (3) In the neutral sheet, the field-aligned current density becomes very large and has a maximum value at the center of the current sheet. (4) In some cases, the current density is a bifurcated one, and the two humps of the current density often superpose two peaks in the gradient of magnetic strength, indicating that the magnetic gradient drift current is possibly responsible for the formation of the two humps of the current density in some tilted current sheets. Tilted current sheets often appear along with tail thick current sheet flapping waves. It is found that, in the tail flapping current sheets, the minimum curvature radius of the MFLs in the current sheet is rather large with values around 1RE, while the neutral sheet may be very thin, with its half thickness being several tenths ofRE. During the flapping waves, the current sheet is tilted substantially, and the maximum tilt angle is generally larger than 45

The effects of respiratory muscle training on peak cough flow in patients with Parkinson's disease: a randomized controlled study.

PubMed

Reyes, Alvaro; Castillo, Adrián; Castillo, Javiera; Cornejo, Isabel

2018-05-01

To compare the effects of an inspiratory versus and expiratory muscle-training program on voluntary and reflex peak cough flow in patients with Parkinson disease. A randomized controlled study. Home-based training program. In all, 40 participants with diagnosis of Parkinson's disease were initially recruited in the study and randomly allocated to three study groups. Of them, 31 participants completed the study protocol (control group, n = 10; inspiratory training group, n = 11; and expiratory training group, n = 10) Intervention: The inspiratory and expiratory group performed a home-based inspiratory and expiratory muscle-training program, respectively (five sets of five repetitions). Both groups trained six times a week for two months using a progressively increased resistance. The control group performed expiratory muscle training using the same protocol and a fixed resistance. Spirometric indices, maximum inspiratory pressure, maximum expiratory pressure, and peak cough flow during voluntary and reflex cough were assessed before and at two months after training. The magnitude of increase in maximum expiratory pressure ( d = 1.40) and voluntary peak cough flow ( d = 0.89) was greater for the expiratory muscle-training group in comparison to the control group. Reflex peak cough flow had a moderate effect ( d = 0.27) in the expiratory group in comparison to the control group. Slow vital capacity ( d = 0.13) and forced vital capacity ( d = 0.02) had trivial effects in the expiratory versus the control group. Two months of expiratory muscle-training program was more beneficial than inspiratory muscle-training program for improving maximum expiratory pressure and voluntary peak cough flow in patients with Parkinson's disease.

Observation of room temperature negative differential resistance in multi-layer heterostructures of quantum dots and conducting polymers.

PubMed

Kannan, V; Kim, M R; Chae, Y S; Ramana, Ch V V; Rhee, J K

2011-01-14

Multi-layer heterostructure negative differential resistance devices based on poly-[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH-PPV) conducting polymer and CdSe quantum dots is reported. The conducting polymer MEH-PPV acts as a barrier while CdSe quantum dots form the well layer. The devices exhibit negative differential resistance (NDR) at low voltages. For these devices, strong negative differential resistance is observed at room temperature. A maximum value of 51 for the peak-to-valley ratio of current is reported. Tunneling of electrons through the discrete quantum confined states in the CdSe quantum dots is believed to be responsible for the multiple peaks observed in the I-V measurement. Depending on the observed NDR signature, operating mechanisms are explored based on resonant tunneling and Coulomb blockade effects.

Estimation of cardiac reserve by peak power: validation and initial application of a simplified index

NASA Technical Reports Server (NTRS)

Armstrong, G. P.; Carlier, S. G.; Fukamachi, K.; Thomas, J. D.; Marwick, T. H.

1999-01-01

OBJECTIVES: To validate a simplified estimate of peak power (SPP) against true (invasively measured) peak instantaneous power (TPP), to assess the feasibility of measuring SPP during exercise and to correlate this with functional capacity. DESIGN: Development of a simplified method of measurement and observational study. SETTING: Tertiary referral centre for cardiothoracic disease. SUBJECTS: For validation of SPP with TPP, seven normal dogs and four dogs with dilated cardiomyopathy were studied. To assess feasibility and clinical significance in humans, 40 subjects were studied (26 patients; 14 normal controls). METHODS: In the animal validation study, TPP was derived from ascending aortic pressure and flow probe, and from Doppler measurements of flow. SPP, calculated using the different flow measures, was compared with peak instantaneous power under different loading conditions. For the assessment in humans, SPP was measured at rest and during maximum exercise. Peak aortic flow was measured with transthoracic continuous wave Doppler, and systolic and diastolic blood pressures were derived from brachial sphygmomanometry. The difference between exercise and rest simplified peak power (Delta SPP) was compared with maximum oxygen uptake (VO(2)max), measured from expired gas analysis. RESULTS: SPP estimates using peak flow measures correlated well with true peak instantaneous power (r = 0.89 to 0.97), despite marked changes in systemic pressure and flow induced by manipulation of loading conditions. In the human study, VO(2)max correlated with Delta SPP (r = 0.78) better than Delta ejection fraction (r = 0.18) and Delta rate-pressure product (r = 0.59). CONCLUSIONS: The simple product of mean arterial pressure and peak aortic flow (simplified peak power, SPP) correlates with peak instantaneous power over a range of loading conditions in dogs. In humans, it can be estimated during exercise echocardiography, and correlates with maximum oxygen uptake better than ejection fraction or rate-pressure product.

Modelling of crater formation on anode surface by high-current vacuum arcs

NASA Astrophysics Data System (ADS)

Tian, Yunbo; Wang, Zhenxing; Jiang, Yanjun; Ma, Hui; Liu, Zhiyuan; Geng, Yingsan; Wang, Jianhua; Nordlund, Kai; Djurabekova, Flyura

2016-11-01

Anode melting and crater formation significantly affect interruption of high-current vacuum arcs. The primary objective of this paper is to theoretically investigate the mechanism of anode surface crater formation, caused by the combined effect of surface heating during the vacuum arc and pressure exerted on the molten surface by ions and electrons from the arc plasma. A model of fluid flow and heat transfer in the arc anode is developed and combined with a magnetohydrodynamics model of the vacuum arc plasma. Crater formation is observed in simulation for a peak arcing current higher than 15 kA on 40 mm diam. Cu electrodes spaced 10 mm apart. The flow of liquid metal starts after 4 or 5 ms of arcing, and the maximum velocities are 0.95 m/s and 1.39 m/s for 20 kA and 25 kA arcs, respectively. This flow redistributes thermal energy, and the maximum temperature of the anode surface does not remain in the center. Moreover, the condition for the liquid droplet formation on the anode surfaces is developed. The solidification process after current zero is also analyzed. The solidification time has been found to be more than 3 ms after 25 kA arcing. The long solidification time and sharp features on crater rims induce Taylor cone formation.

Design of electrodes and current limits for low frequency electrical impedance tomography of the brain.

PubMed

Gilad, O; Horesh, L; Holder, D S

2007-07-01

For the novel application of recording of resistivity changes related to neuronal depolarization in the brain with electrical impedance tomography, optimal recording is with applied currents below 100 Hz, which might cause neural stimulation of skin or underlying brain. The purpose of this work was to develop a method for application of low frequency currents to the scalp, which delivered the maximum current without significant stimulation of skin or underlying brain. We propose a recessed electrode design which enabled current injection with an acceptable skin sensation to be increased from 100 muA using EEG electrodes, to 1 mA in 16 normal volunteers. The effect of current delivered to the brain was assessed with an anatomically realistic finite element model of the adult head. The modelled peak cerebral current density was 0.3 A/m(2), which was 5 to 25-fold less than the threshold for stimulation of the brain estimated from literature review.

ICRF fast wave current drive and mode conversion current drive in EAST tokamak

NASA Astrophysics Data System (ADS)

Yin, L.; Yang, C.; Gong, X. Y.; Lu, X. Q.; Du, D.; Chen, Y.

2017-10-01

Fast wave in the ion-cyclotron resonance frequency (ICRF) range is a promising candidate for non-inductive current drive (CD), which is essential for long pulse and high performance operation of tokamaks. A numerical study on the ICRF fast wave current drive (FWCD) and mode-conversion current drive (MCCD) in the Experimental Advanced Superconducting Tokamak (EAST) is carried out by means of the coupled full wave and Ehst-Karney parameterization methods. The results show that FWCD efficiency is notable in two frequency regimes, i.e., f ≥ 85 MHz and f = 50-65 MHz, where ion cyclotron absorption is effectively avoided, and the maximum on-axis driven current per unit power can reach 120 kA/MW. The sensitivity of the CD efficiency to the minority ion concentration is confirmed, owing to fast wave mode conversion, and the peak MCCD efficiency is reached for 22% minority-ion concentration. The effects of the wave-launch position and the toroidal wavenumber on the efficiency of current drive are also investigated.

Design analysis and simulation study of an efficiency enhanced L-band MILO

NASA Astrophysics Data System (ADS)

Dixit, Gargi; Kumar, Arjun; Jain, P. K.

2017-01-01

In this article, an experimental L-band compact magnetically insulated transmission line oscillator (MILO) has been simulated using the 3D PIC simulation code "Particle Studio," and an improvement in the device efficiency has been obtained. The detailed interaction and operating mechanism describing the role of sub-assemblies have been explained. The performance of the device was found to be the function of the distance between the end-surface of the cathode and the beam-dump disk. During simulation, a high power microwave of the TM01 mode is generated with the peak RF-power of 6 GW and the power conversion efficiency of 19.2%, at the operating voltage of ˜600 kV and at the current of 52 kA. For better impedance matching or maximum power transfer, four stubs have been placed at the λg/4 distance from the extractor cavity, which results in the stable RF power output. In this work, an improved L-band MILO along with a new type beam-dump disk is selected for performance improvement with typical design parameters and beam parameters. The total peak power of improved MILO is 7 GW, and the maximum power conversion efficiency is 22.4%. This improvement is achieved due to the formation of the virtual cathode at the load side, which helps in modulating the energy of electrons owing to maximum reflection of electrons from the mesh or foil.

Analysis of the Magnitude and Frequency of Peak Discharge and Maximum Observed Peak Discharge in New Mexico and Surrounding Areas

USGS Publications Warehouse

Waltemeyer, Scott D.

2008-01-01

Estimates of the magnitude and frequency of peak discharges are necessary for the reliable design of bridges, culverts, and open-channel hydraulic analysis, and for flood-hazard mapping in New Mexico and surrounding areas. The U.S. Geological Survey, in cooperation with the New Mexico Department of Transportation, updated estimates of peak-discharge magnitude for gaging stations in the region and updated regional equations for estimation of peak discharge and frequency at ungaged sites. Equations were developed for estimating the magnitude of peak discharges for recurrence intervals of 2, 5, 10, 25, 50, 100, and 500 years at ungaged sites by use of data collected through 2004 for 293 gaging stations on unregulated streams that have 10 or more years of record. Peak discharges for selected recurrence intervals were determined at gaging stations by fitting observed data to a log-Pearson Type III distribution with adjustments for a low-discharge threshold and a zero skew coefficient. A low-discharge threshold was applied to frequency analysis of 140 of the 293 gaging stations. This application provides an improved fit of the log-Pearson Type III frequency distribution. Use of the low-discharge threshold generally eliminated the peak discharge by having a recurrence interval of less than 1.4 years in the probability-density function. Within each of the nine regions, logarithms of the maximum peak discharges for selected recurrence intervals were related to logarithms of basin and climatic characteristics by using stepwise ordinary least-squares regression techniques for exploratory data analysis. Generalized least-squares regression techniques, an improved regression procedure that accounts for time and spatial sampling errors, then were applied to the same data used in the ordinary least-squares regression analyses. The average standard error of prediction, which includes average sampling error and average standard error of regression, ranged from 38 to 93 percent (mean value is 62, and median value is 59) for the 100-year flood. The 1996 investigation standard error of prediction for the flood regions ranged from 41 to 96 percent (mean value is 67, and median value is 68) for the 100-year flood that was analyzed by using generalized least-squares regression analysis. Overall, the equations based on generalized least-squares regression techniques are more reliable than those in the 1996 report because of the increased length of record and improved geographic information system (GIS) method to determine basin and climatic characteristics. Flood-frequency estimates can be made for ungaged sites upstream or downstream from gaging stations by using a method that transfers flood-frequency data at the gaging station to the ungaged site by using a drainage-area ratio adjustment equation. The peak discharge for a given recurrence interval at the gaging station, drainage-area ratio, and the drainage-area exponent from the regional regression equation of the respective region is used to transfer the peak discharge for the recurrence interval to the ungaged site. Maximum observed peak discharge as related to drainage area was determined for New Mexico. Extreme events are commonly used in the design and appraisal of bridge crossings and other structures. Bridge-scour evaluations are commonly made by using the 500-year peak discharge for these appraisals. Peak-discharge data collected at 293 gaging stations and 367 miscellaneous sites were used to develop a maximum peak-discharge relation as an alternative method of estimating peak discharge of an extreme event such as a maximum probable flood.

Chemometric Analysis of Gas Chromatography – Mass Spectrometry Data using Fast Retention Time Alignment via a Total Ion Current Shift Function

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

Nadeau, Jeremy S.; Wright, Bob W.; Synovec, Robert E.

2010-04-15

A critical comparison of methods for correcting severely retention time shifted gas chromatography-mass spectrometry (GC-MS) data is presented. The method reported herein is an adaptation to the Piecewise Alignment Algorithm to quickly align severely shifted one-dimensional (1D) total ion current (TIC) data, then applying these shifts to broadly align all mass channels throughout the separation, referred to as a TIC shift function (SF). The maximum shift varied from (-) 5 s in the beginning of the chromatographic separation to (+) 20 s toward the end of the separation, equivalent to a maximum shift of over 5 peak widths. Implementing themore » TIC shift function (TIC SF) prior to Fisher Ratio (F-Ratio) feature selection and then principal component analysis (PCA) was found to be a viable approach to classify complex chromatograms, that in this study were obtained from GC-MS separations of three gasoline samples serving as complex test mixtures, referred to as types C, M and S. The reported alignment algorithm via the TIC SF approach corrects for large dynamic shifting in the data as well as subtle peak-to-peak shifts. The benefits of the overall TIC SF alignment and feature selection approach were quantified using the degree-of-class separation (DCS) metric of the PCA scores plots using the type C and M samples, since they were the most similar, and thus the most challenging samples to properly classify. The DCS values showed an increase from an initial value of essentially zero for the unaligned GC-TIC data to a value of 7.9 following alignment; however, the DCS was unchanged by feature selection using F-Ratios for the GC-TIC data. The full mass spectral data provided an increase to a final DCS of 13.7 after alignment and two-dimensional (2D) F-Ratio feature selection.« less

Climate change is projected to have severe impacts on the frequency and intensity of peak electricity demand across the United States.

PubMed

Auffhammer, Maximilian; Baylis, Patrick; Hausman, Catherine H

2017-02-21

It has been suggested that climate change impacts on the electric sector will account for the majority of global economic damages by the end of the current century and beyond [Rose S, et al. (2014) Understanding the Social Cost of Carbon: A Technical Assessment ]. The empirical literature has shown significant increases in climate-driven impacts on overall consumption, yet has not focused on the cost implications of the increased intensity and frequency of extreme events driving peak demand, which is the highest load observed in a period. We use comprehensive, high-frequency data at the level of load balancing authorities to parameterize the relationship between average or peak electricity demand and temperature for a major economy. Using statistical models, we analyze multiyear data from 166 load balancing authorities in the United States. We couple the estimated temperature response functions for total daily consumption and daily peak load with 18 downscaled global climate models (GCMs) to simulate climate change-driven impacts on both outcomes. We show moderate and heterogeneous changes in consumption, with an average increase of 2.8% by end of century. The results of our peak load simulations, however, suggest significant increases in the intensity and frequency of peak events throughout the United States, assuming today's technology and electricity market fundamentals. As the electricity grid is built to endure maximum load, our findings have significant implications for the construction of costly peak generating capacity, suggesting additional peak capacity costs of up to 180 billion dollars by the end of the century under business-as-usual.

Global Investigation of the Mg Atom and ion Layers using SCIAMACHY/Envisat Observations between 70 km and 150 km Altitude and WACCM-MG Model Results

NASA Technical Reports Server (NTRS)

Langowski, M.; vonSavigny, C.; Burrows, J. P.; Feng, W.; Plane, J. M. C.; Marsh, D. R.; Janches, Diego; Sinnhuber, M.; Aikin, A. C.

2014-01-01

Mg and Mg+ concentration fields in the upper mesosphere/lower thermosphere (UMLT) region are retrieved from SCIAMACHY/Envisat limb measurements of Mg and Mg+ dayglow emissions using a 2-D tomographic retrieval approach. The time series of monthly means of Mg and Mg+ for number density as well as vertical column density in different latitudinal regions are shown. Data from the limb mesosphere-thermosphere mode of SCIAMACHY/Envisat are used, which covers the 50 km to 150 km altitude region with a vertical sampling of 3.3 km and a highest latitude of 82 deg. The high latitudes are not covered in the winter months, because there is no dayglow emission during polar night. The measurements were performed every 14 days from mid-2008 until April 2012. Mg profiles show a peak at around 90 km altitude with a density between 750 cm(exp-3) and 2000 cm(exp-3). Mg does not show strong seasonal variation at mid-latitudes. The Mg+ peak occurs 5-15 km above the neutral Mg peak at 95-105 km. Furthermore, the ions show a significant seasonal cycle with a summer maximum in both hemispheres at mid- and high-latitudes. The strongest seasonal variations of the ions are observed at mid-latitudes between 20-40 deg and densities at the peak altitude range from 500 cm(exp-3) to 6000 cm(exp-3). The peak altitude of the ions shows a latitudinal dependence with a maximum at mid-latitudes that is up to 10 km higher than the peak altitude at the equator. The SCIAMACHY measurements are compared to other measurements and WACCM model results. In contrast to the SCIAMACHY results, the WACCM results show a strong seasonal variability for Mg with a winter maximum, which is not observable by SCIAMACHY, and globally higher peak densities. Although the peak densities do not agree the vertical column densities agree, since SCIAMACHY results show a wider vertical profile. The agreement of SCIAMACHY and WACCM results is much better for Mg+, showing the same seasonality and similar peak densities. However, there are the following minor differences: there is no latitudinal dependence of the peak altitude for WACCM and the density maximum, passing the equatorial region during equinox conditions, is not reduced as for SCIAMACHY.

Calculation of induced current densities for humans by magnetic fields from electronic article surveillance devices

NASA Astrophysics Data System (ADS)

Gandhi, Om P.; Kang, Gang

2001-11-01

This paper illustrates the use of the impedance method to calculate the electric fields and current densities induced in millimetre resolution anatomic models of the human body, namely an adult and 10- and 5-year-old children, for exposure to nonuniform magnetic fields typical of two assumed but representative electronic article surveillance (EAS) devices at 1 and 30 kHz, respectively. The devices assumed for the calculations are a solenoid type magnetic deactivator used at store checkouts and a pass-by panel-type EAS system consisting of two overlapping rectangular current-carrying coils used at entry and exit from a store. The impedance method code is modified to obtain induced current densities averaged over a cross section of 1 cm2 perpendicular to the direction of induced currents. This is done to compare the peak current densities with the limits or the basic restrictions given in the ICNIRP safety guidelines. Because of the stronger magnetic fields at lower heights for both the assumed devices, the peak 1 cm2 area-averaged current densities for the CNS tissues such as the brain and the spinal cord are increasingly larger for smaller models and are the highest for the model of the 5-year-old child. For both the EAS devices, the maximum 1 cm2 area-averaged current densities for the brain of the model of the adult are lower than the ICNIRP safety guideline, but may approach or exceed the ICNIRP basic restrictions for models of 10- and 5-year-old children if sufficiently strong magnetic fields are used.

Calculation of induced current densities for humans by magnetic fields from electronic article surveillance devices.

PubMed

Gandhi, O P; Kang, G

2001-11-01

This paper illustrates the use of the impedance method to calculate the electric fields and current densities induced in millimetre resolution anatomic models of the human body, namely an adult and 10- and 5-year-old children, for exposure to nonuniform magnetic fields typical of two assumed but representative electronic article surveillance (EAS) devices at 1 and 30 kHz, respectively. The devices assumed for the calculations are a solenoid type magnetic deactivator used at store checkouts and a pass-by panel-type EAS system consisting of two overlapping rectangular current-carrying coils used at entry and exit from a store. The impedance method code is modified to obtain induced current densities averaged over a cross section of 1 cm2 perpendicular to the direction of induced currents. This is done to compare the peak current densities with the limits or the basic restrictions given in the ICNIRP safety guidelines. Because of the stronger magnetic fields at lower heights for both the assumed devices, the peak 1 cm2 area-averaged current densities for the CNS tissues such as the brain and the spinal cord are increasingly larger for smaller models and are the highest for the model of the 5-year-old child. For both the EAS devices, the maximum 1 cm2 area-averaged current densities for the brain of the model of the adult are lower than the ICNIRP safety guideline, but may approach or exceed the ICNIRP basic restrictions for models of 10- and 5-year-old children if sufficiently strong magnetic fields are used.

Method and apparatus for current-output peak detection

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

De Geronimo, Gianluigi

2017-01-24

A method and apparatus for a current-output peak detector. A current-output peak detector circuit is disclosed and works in two phases. The peak detector circuit includes switches to switch the peak detector circuit from the first phase to the second phase upon detection of the peak voltage of an input voltage signal. The peak detector generates a current output with a high degree of accuracy in the second phase.

Wind-enhanced resuspension in the shallow waters of South San Francisco Bay: Mechanisms and potential implications for cohesive sediment transport

USGS Publications Warehouse

Brand, Andreas; Lacy, Jessica R.; Hsu, Kevin; Hoover, Daniel; Gladding, Steve; Stacey, Mark T.

2010-01-01

We investigated the driving forces of sediment dynamics at the shoals in South San Francisco Bay. Two stations were deployed along a line perpendicular to a 14 m deep channel, 1000 and 2000 m from the middle of the channel. Station depths were 2.59 and 2.19 m below mean lower low water, respectively. We used acoustic Doppler velocimeters for the simultaneous determination of current velocities, turbulence, sediment concentration and fluxes. Maximum current shear velocities were 0.015 m s−1 at the station further from the channel (closer to the shore) and 0.02 m s−1 at the station closer to the channel. Peak wave-induced shear velocities exceeded 0.015 m s−1 at both stations. Maximum sediment concentrations were around 30 g m−3 during calm periods (root mean square wave height −3 and sediment fluxes were 5 times higher than in calm conditions (0.02 g m−2 s−1 versus >0.10 g m−2 s−1) at the station further from the channel 0.36 m above the bed. Closer to the channel, sediment concentrations and vertical fluxes due to wind wave resuspension were persistently lower (maximum concentrations around 50 g m−3 and maximum fluxes around 0.04 g m−2 s−1). Most resuspension events occurred during flood tides that followed wave events during low water. Although wave motions are able to resuspend sediment into the wave boundary layer at low tide, the observed large increases in sediment fluxes are due to the nonlinear interaction of wind waves and the tidal currents.

Cloth-Based Power Shirt for Wearable Energy Harvesting and Clothes Ornamentation.

PubMed

Li, Suling; Zhong, Qize; Zhong, Junwen; Cheng, Xiaofeng; Wang, Bo; Hu, Bin; Zhou, Jun

2015-07-15

Harvesting ambient mechanical energy from human body motion has attracted great research interest. In this work, a power shirt based on triboelectrification and the electrostatic induction effect between fluorinated ethylene propylene (FEP) and external objects is demonstrated. This power shirt can effectively convert the ambient mechanical energy into electric power, and the working mechanism is systematically discussed. A maximum short-circuit current density of ∼0.37 μA/cm2 and a maximum peak power density of ∼4.65 μW/cm2 were achieved. Simultaneously, 11 blue LEDs were lit by sliding the sleeve and power shirt, indicating the potential application of the power shirt in clothes ornamentation and risk warning. This study develops an efficient path for harvesting human body energy and promoting the development of wearable electronics and smart garments.

Characterization of diode-laser stacks for high-energy-class solid state lasers

NASA Astrophysics Data System (ADS)

Pilar, Jan; Sikocinski, Pawel; Pranowicz, Alina; Divoky, Martin; Crump, P.; Staske, R.; Lucianetti, Antonio; Mocek, Tomas

2014-03-01

In this work, we present a comparative study of high power diode stacks produced by world's leading manufacturers such as DILAS, Jenoptik, and Quantel. The diode-laser stacks are characterized by central wavelength around 939 nm, duty cycle of 1 %, and maximum repetition rate of 10 Hz. The characterization includes peak power, electrical-to-optical efficiency, central wavelength and full width at half maximum (FWHM) as a function of diode current and cooling temperature. A cross-check of measurements performed at HiLASE-IoP and Ferdinand-Braun-Institut (FBH) shows very good agreement between the results. Our study reveals also the presence of discontinuities in the spectra of two diode stacks. We consider the results presented here a valuable tool to optimize pump sources for ultra-high average power lasers, including laser fusion facilities.

Dephasing effects on ac-driven triple quantum dot systems

NASA Astrophysics Data System (ADS)

Maldonado, I.; Villavicencio, J.; Contreras-Pulido, L. D.; Cota, E.; Maytorena, J. A.

2018-05-01

We analyze the effect of environmental dephasing on the electrical current in an ac-driven triple quantum dot system in a symmetric Λ configuration. The current is explored by solving the time evolution equation of the density matrix as a function of the frequency and amplitude of the driving field. Two characteristic spectra are observed depending on the field amplitude. At the resonance condition, when the frequency matches the interdot energy difference, one spectrum shows a distinctive Fano-type peak, while the other, occurring at larger values of the field amplitude, exhibits a strong current suppression due to dynamic localization. In the former case we observe that the current maximum is reduced due to dephasing, while in the latter it is shown that dephasing partially alleviates the localization. In both cases, away from resonance, we observe current oscillations which are dephasing-enhanced for a wide range of frequencies. These effects are also discussed using Floquet theory, and analytical expressions for the electrical current are obtained within the rotating wave approximation.

Development of magnitude scaling relationship for earthquake early warning system in South Korea

NASA Astrophysics Data System (ADS)

Sheen, D.

2011-12-01

Seismicity in South Korea is low and magnitudes of recent earthquakes are mostly less than 4.0. However, historical earthquakes of South Korea reveal that many damaging earthquakes had occurred in the Korean Peninsula. To mitigate potential seismic hazard in the Korean Peninsula, earthquake early warning (EEW) system is being installed and will be operated in South Korea in the near future. In order to deliver early warnings successfully, it is very important to develop stable magnitude scaling relationships. In this study, two empirical magnitude relationships are developed from 350 events ranging in magnitude from 2.0 to 5.0 recorded by the KMA and the KIGAM. 1606 vertical component seismograms whose epicentral distances are within 100 km are chosen. The peak amplitude and the maximum predominant period of the initial P wave are used for finding magnitude relationships. The peak displacement of seismogram recorded at a broadband seismometer shows less scatter than the peak velocity of that. The scatters of the peak displacement and the peak velocity of accelerogram are similar to each other. The peak displacement of seismogram differs from that of accelerogram, which means that two different magnitude relationships for each type of data should be developed. The maximum predominant period of the initial P wave is estimated after using two low-pass filters, 3 Hz and 10 Hz, and 10 Hz low-pass filter yields better estimate than 3 Hz. It is found that most of the peak amplitude and the maximum predominant period are estimated within 1 sec after triggering.

Streamflow and Erosion Response to Prolonged Intense Rainfall of November 1-2, 2000, Island of Hawaii, Hawaii

USGS Publications Warehouse

Fontaine, Richard A.; Hill, Barry R.

2002-01-01

A combination of several meteorologic and topographic factors produced extreme rainfall over the eastern part of the island of Hawaii on November 1-2, 2000. Storm rainfall was concentrated in two distinct areas, the Waiakea and Kapapala areas, where maximum rainfall totals of 32.47 and 38.97 inches were recorded. Resultant flooding caused damages in excess of 70 million dollars, among the highest totals associated with flooding in the State's history. Storm rainfall had recurrence intervals that ranged from 10 years or less for maximum 1-hour totals to 100 years or more for maximum 24-hour totals As part of this study, peak flow and/or erosion data were collected at 41 sites. Analyses of these data indicated that peak discharges of record occurred at 6 of 12 sites where historic data were available. Peak flows with estimated recurrence intervals from 50 to over 100 years were recorded at 4 of 11 sites. Peak flows were poorly correlated with total storm rainfall. Critical rainfall durations associated with peak flows ranged from 1 to 12 hours and were about 3 hours at most sites. Rainfall-runoff computations and field observations indicated that infiltration-excess overland flow alone was not sufficient to have caused the observed flood peaks and therefore saturation-excess overland flow and subsurface flow probably contributed to peak flows at most sites Most hillslope erosion associated with the storm took place along or near the Kaoiki Pali in the Kapapala area. Hillslope erosion was predominately caused by overland flow.

[Positive inotropic and lusitropic effect of RP 62719, a new class III antiarrhythmia agent].

PubMed

Beregi, J P; Escande, D; Coudray, N; Chemla, D; Mestre, M; Péry, N; Lecarpentier, Y

1994-02-01

Antiarrhythmic drugs, especially the Class I family, exert a negative inotropic effect on the myocardium which is particularly undesirable in patients with depressed left ventricular function. Therefore, research has been directed to the development of new, more specific molecules of the Class III family. The authors studies the mechanical effects of RP 62719 on guinea pig left ventricular papillary muscle. This new molecule is a pure Class III antiarrhythmic, known to lengthen the duration of the cardiac action potential by selectively blocking the potassium current iK1 (inward rectifier K+ current). The mechanical parameters were determined during the phases of contraction and relaxation under isotonic and isometric conditions. At 0.2 and 2 microM concentrations, RP 62719 improved cardiac contraction under both isotonic and isometric conditions with an increase of about 30% of Vmax (p < 0.001), the maximum unloaded shortening velocity delta 1 (p < 0.001), the peak isometric active force normalized per cross-sectional area [AF/S (p < 0.001)]. At these two concentrations, a positive lusitropic effect (improved relaxation) was demonstrated by an increase in negative peak of derivative per mm2-dF/s and maximum lengthening velocity VR max (p < 0.01). At higher concentrations (20 microM), the inotropic and lusitropic effects were less marked with a bell-shaped form of the dose-effect curve. This study indicates that RP 62719 has moderate but significant positive inotropic and lusitropic effects. These actions could provide significant therapeutic advantages especially in patients cardiac failure.

Subjective and Cardiovascular Effects of Intravenous Methamphetamine during Perindopril Maintenance: A Randomized, Double-Blind, Placebo-Controlled Human Laboratory Study.

PubMed

Verrico, Christopher D; Haile, Colin N; De La Garza, Richard; Grasing, Kenneth; Kosten, Thomas R; Newton, Thomas F

2016-07-01

Our pilot study suggested that the angiotensin-converting enzyme inhibitor perindopril might reduce some subjective effects produced by i.v. methamphetamine. We characterized the impact of a wider range of perindopril doses on methamphetamine-induced effects in a larger group of non-treatment-seeking, methamphetamine-using volunteers. Before treatment, participants received 30mg methamphetamine. After 5 to 7 days of perindopril treatment (0, 4, 8, or 16mg/d), participants received 15 and 30mg of methamphetamine on alternate days. Before and after treatment, participants rated subjective effects and cardiovascular measures were collected. Prior to treatment with perindopril, there were no significant differences between treatment groups on maximum or peak subjective ratings or on peak cardiovascular effects. Following perindopril treatment, there were significant main effects of treatment on peak subjective ratings of "anxious" and "stimulated"; compared to placebo treatment, treatment with 8mg perindopril significantly reduced peak ratings of both anxious (P=.0009) and stimulated (P=.0070). There were no significant posttreatment differences between groups on peak cardiovascular effects. Moderate doses of perindopril (8mg) significantly reduced peak subjective ratings of anxious and stimulated as well as attenuated many other subjective effects produced by methamphetamine, likely by inhibiting angiotensin II synthesis. Angiotensin II is known to facilitate the effects of norepinephrine, which contributes to methamphetamine's subjective effects. The lack of a classic dose-response function likely results from either nonspecific effects of perindopril or from between-group differences that were not accounted for in the current study (i.e., genetic variations and/or caffeine use). The current findings suggest that while angiotensin-converting enzyme inhibitors can reduce some effects produced by methamphetamine, more consistent treatment effects might be achieved by targeting components of the renin-angiotensin system that are downstream of angiotensin-converting enzyme. © The Author 2016. Published by Oxford University Press on behalf of CINP.

Different signaling pathway between sphingosine-1-phosphate and lysophosphatidic acid in Xenopus oocytes: functional coupling of the sphingosine-1-phosphate receptor to PLC-xbeta in Xenopus oocytes.

PubMed

Noh, S J; Kim, M J; Shim, S; Han, J K

1998-08-01

In Xenopus oocytes, both sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) activate Ca2+-dependent oscillatory Cl- currents by acting through membrane-bound receptors. External application of 50 microM S1P elicited a long-lasting oscillatory current that continued over 30 min from the beginning of oscillation, with 300 nA (n = 11) as a usual maximum peak of current, whereas 1-microM LPA treatment showed only transiently oscillating but more vigorous current responses, with 2,800 nA (n = 18) as a maximum peak amplitude. Both phospholipid-induced Ca2+-dependent Cl- currents were observed in the absence of extracellular Ca2+, were blocked by intracellular injection of the Ca2+ chelator, EGTA, and could not be elicited by treatment with thapsigargin, an inhibitor of endoplasmic reticulum (ER) Ca2+ ATPase. Intracellular Ca2+ release appeared to be from inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ store, because Cl- currents were blocked by heparin injection. Pretreatment with the aminosteroid, U-73122, an inhibitor of G protein-mediated phospholipase C (PLC) activation, to oocytes inhibited the current responses evoked both by S1P and LPA. However, when they were injected with 10 ng of antisense oligonucleotide (AS-ODN) against Xenopus phospholipase C (PLC-xbeta), oocytes could not respond to S1P application, whereas they responded normally to LPA, indicating that the S1P signaling pathway goes through PLC-xbeta, whereas LPA signaling goes through another unknown PLC. To determine the types of G proteins involved, we introduced AS-ODNs against four types of G-protein alpha subunits that were identified in Xenopus laevis; G(q)alpha, G11alpha, G0alpha, and G(i1)alpha. Among AS-ODNs against the G alphas tested, AS-G(q)alpha and AS-G(i1)alpha to S1P and AS-G(q)alpha and AS-G11alpha to LPA specifically reduced current responses, respectively, to about 20-30% of controls. These results demonstrate that LPA and S1P, although they have similar structural features, release intracellular Ca2+ from the IP3-sensitive pool, use different components in their signal transduction pathways in Xenopus oocytes.

Evaluation of peak force of a manually operated chiropractic adjusting instrument with an adapter for use in animals.

PubMed

Duarte, Felipe Coutinho Kullmann; Kolberg, Carolina; Barros, Rodrigo R; Silva, Vivian G A; Gehlen, Günter; Vassoler, Jakson M; Partata, Wania A

2014-05-01

This study was designed to assess the peak force of a manually operated chiropractic adjusting instrument, the Activator Adjusting Instrument 4 (AAI 4), with an adapter for use in animals, which has a 3- to 4-fold smaller contact surface area than the original rubber tip. Peak force was determined by thrusting the AAI 4 with the adapter or the original rubber tip onto a load cell. First, the AAI 4 was applied perpendicularly by a doctor of chiropractic onto the load cell. Then, the AAI 4 was fixed in a rigid framework and applied to the load cell. This procedure was done to prevent any load on the load cell before the thrust impulse. In 2 situations, trials were performed with the AAI 4 at all force settings (settings I, II, III, and IV, minimum to maximum, respectively). A total of 50000 samples per second over a period of 3 seconds were collected. In 2 experimental protocols, the use of the adapter in the AAI 4 increased the peak force only with setting I. The new value was around 80% of the maximum value found for the AAI 4. Nevertheless, the peak force values of the AAI 4 with the adapter and with the original rubber tip in setting IV were similar. The adapter effectively determines the maximum peak force value at force setting I of AAI 4. Copyright © 2014 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

Volumetric velocity measurements in restricted geometries using spiral sampling: a phantom study.

PubMed

Nilsson, Anders; Revstedt, Johan; Heiberg, Einar; Ståhlberg, Freddy; Bloch, Karin Markenroth

2015-04-01

The aim of this study was to evaluate the accuracy of maximum velocity measurements using volumetric phase-contrast imaging with spiral readouts in a stenotic flow phantom. In a phantom model, maximum velocity, flow, pressure gradient, and streamline visualizations were evaluated using volumetric phase-contrast magnetic resonance imaging (MRI) with velocity encoding in one (extending on current clinical practice) and three directions (for characterization of the flow field) using spiral readouts. Results of maximum velocity and pressure drop were compared to computational fluid dynamics (CFD) simulations, as well as corresponding low-echo-time (TE) Cartesian data. Flow was compared to 2D through-plane phase contrast (PC) upstream from the restriction. Results obtained with 3D through-plane PC as well as 4D PC at shortest TE using a spiral readout showed excellent agreements with the maximum velocity values obtained with CFD (<1 % for both methods), while larger deviations were seen using Cartesian readouts (-2.3 and 13 %, respectively). Peak pressure drop calculations from 3D through-plane PC and 4D PC spiral sequences were respectively 14 and 13 % overestimated compared to CFD. Identification of the maximum velocity location, as well as the accurate velocity quantification can be obtained in stenotic regions using short-TE spiral volumetric PC imaging.

Near-fault peak ground velocity from earthquake and laboratory data

USGS Publications Warehouse

McGarr, A.; Fletcher, Joe B.

2007-01-01

We test the hypothesis that peak ground velocity (PGV) has an upper bound independent of earthquake magnitude and that this bound is controlled primarily by the strength of the seismogenic crust. The highest PGVs, ranging up to several meters per second, have been measured at sites within a few kilometers of the causative faults. Because the database for near-fault PGV is small, we use earthquake slip models, laboratory experiments, and evidence from a mining-induced earthquake to investigate the factors influencing near-fault PGV and the nature of its scaling. For each earthquake slip model we have calculated the peak slip rates for all subfaults and then chosen the maximum of these rates as an estimate of twice the largest near-fault PGV. Nine slip models for eight earthquakes, with magnitudes ranging from 6.5 to 7.6, yielded maximum peak slip rates ranging from 2.3 to 12 m/sec with a median of 5.9 m/sec. By making several adjustments, PGVs for small earthquakes can be simulated from peak slip rates measured during laboratory stick-slip experiments. First, we adjust the PGV for differences in the state of stress (i.e., the difference between the laboratory loading stresses and those appropriate for faults at seismogenic depths). To do this, we multiply both the slip and the peak slip rate by the ratio of the effective normal stresses acting on fault planes measured at 6.8 km depth at the KTB site, Germany (deepest available in situ stress measurements), to those acting on the laboratory faults. We also adjust the seismic moment by replacing the laboratory fault with a buried circular shear crack whose radius is chosen to match the experimental unloading stiffness. An additional, less important adjustment is needed for experiments run in triaxial loading conditions. With these adjustments, peak slip rates for 10 stick-slip events, with scaled moment magnitudes from -2.9 to 1.0, range from 3.3 to 10.3 m/sec, with a median of 5.4 m/sec. Both the earthquake and laboratory results are consistent with typical maximum peak slip rates averaging between 5 and 6 m/sec or corresponding maximum near-fault PGVs between 2.5 and 3 m/sec at seismogenic depths, independent of magnitude. Our ability to replicate maximum slip rates in the fault zones of earthquakes by adjusting the corresponding laboratory rates using the ratio of effective normal stresses acting on the fault planes suggests that the strength of the seismogenic crust is the important factor limiting the near-fault PGV.

Comparison of current distributions in electroconvulsive therapy and transcranial magnetic stimulation

NASA Astrophysics Data System (ADS)

Sekino, Masaki; Ueno, Shoogo

2002-05-01

We compared current density distributions in electroconvulsive therapy (ECT) and transcranial magnetic stimulation (TMS) by numerical calculations. The model consisted of an air region and three types of tissues with different conductivities representing the brain, the skull, and the scalp. In the ECT model, electric currents were applied through electrodes with a voltage of 100 V. In the TMS model, a figure-eight coil (6 cm diameter per coil) was placed on the vertex of the head model. An alternating current with a peak intensity of 3.0 kA and a frequency of 4.2 kHz was applied to the coil. The maximum current densities inside the brain in ECT (bilateral electrode position) and TMS were 234 and 322 A/m2, respectively. The results indicate that magnetic stimulators can generate comparable current densities to ECT. While the skull significantly affected current distributions in ECT, TMS efficiently induced eddy currents in the brain. In addition, TMS is more beneficial than ECT because the localized current distribution reduces the risk of adverse side effects.

Species diversity: Benthonic Foraminifera in Western North Atlantic

USGS Publications Warehouse

Buzas, M.A.; Gibson, T.G.

1969-01-01

Maximum species diversity occurs at abyssal depths of greater than 2500 meters. Other diversity peaks occur at depths of 35 to 45 meters and 100 to 200 meters. The peak at 35 to 45 meters is due to species equitability, whereas the other two peaks correspond to an increase in the number of species.

A Systematic Review of Isometric Lingual Strength-Training Programs in Adults With and Without Dysphagia

PubMed Central

Zhang, Bin; Haines, Morgan B.; Kelchner, Lisa N.

2017-01-01

Purpose This systematic review summarizes the effects of isometric lingual strength training on lingual strength and swallow function in adult populations. Furthermore, it evaluates the designs of the reviewed studies and identifies areas of future research in isometric lingual strength training for dysphagia remediation. Method A comprehensive literature search of 3 databases and additional backward citation search identified 10 studies for inclusion in the review. The review reports and discusses the isometric-exercise intervention protocols, pre- and postintervention lingual-pressure data (maximum peak pressures and lingual-palatal pressures during swallowing), and oropharyngeal swallowing measures such as penetration-aspiration scales, oropharyngeal residue and duration, lingual volumes, and quality-of-life assessments. Results Studies reported gains in maximum peak lingual pressures following isometric lingual strength training for both healthy adults and select groups of individuals with dysphagia. However, due to the variability in study designs, it remains unclear whether strength gains generalize to swallow function. Conclusion Although isometric lingual strength training is a promising intervention for oropharyngeal dysphagia, the current literature is too variable to confidently report specific therapeutic benefits. Future investigations should target homogenous patient populations and use randomized controlled trials to determine the efficacy of this treatment for individuals with dysphagia. PMID:28282484

A compact, low jitter, nanosecond rise time, high voltage pulse generator with variable amplitude.

PubMed

Mao, Jiubing; Wang, Xin; Tang, Dan; Lv, Huayi; Li, Chengxin; Shao, Yanhua; Qin, Lan

2012-07-01

In this paper, a compact, low jitter, nanosecond rise time, command triggered, high peak power, gas-switch pulse generator system is developed for high energy physics experiment. The main components of the system are a high voltage capacitor, the spark gap switch and R = 50 Ω load resistance built into a structure to obtain a fast high power pulse. The pulse drive unit, comprised of a vacuum planar triode and a stack of avalanche transistors, is command triggered by a single or multiple TTL (transistor-transistor logic) level pulses generated by a trigger pulse control unit implemented using the 555 timer circuit. The control unit also accepts user input TTL trigger signal. The vacuum planar triode in the pulse driving unit that close the first stage switches is applied to drive the spark gap reducing jitter. By adjusting the charge voltage of a high voltage capacitor charging power supply, the pulse amplitude varies from 5 kV to 10 kV, with a rise time of <3 ns and the maximum peak current up to 200 A (into 50 Ω). The jitter of the pulse generator system is less than 1 ns. The maximum pulse repetition rate is set at 10 Hz that limited only by the gas-switch and available capacitor recovery time.

A comparison of peak power in the shoulder press and shoulder throw.

PubMed

Dalziel, W M; Neal, R J; Watts, M C

2002-09-01

The ability to generate peak power is central for performance in many sports. Currently two distinct resistance training methods are used to develop peak power, the heavy weight/slow velocity and light weight/fast velocity regimes. When using the light weight/fast velocity power training method it was proposed that peak power would be greater in a shoulder throw exercise compared with a normal shoulder press. Nine males performed three lifts in the shoulder press and shoulder throw at 30% and 40% of their one repetition maximum (1RM). These lifts were performed identically, except for the release of the bar in the throw condition. A potentiometer attached to the bar measured displacement and duration of the lifts. The time of bar release in the shoulder throw was determined with a pressure switch. ANOVA was used to examine statistically significant differences where the level of acceptance was set at p < 0.05. Peak power was found to be significantly greater in the shoulder throw at 30% of 1 RM condition [F, (1, 23) = 2.325 p < 0.051 and at 40% of 1 RM [F, (1, 23) = 2.905 p < 0.05] compared to values recorded for the respective shoulder presses. Peak power was also greater in the 30% of 1 RM shoulder throw (510 +/- 103W) than in the 40% of 1 RM shoulder press (471 +/- 96W). Peak power was produced significantly later in the shoulder throw versus the shoulder press. This differing power reflected a greater bar velocity of the shoulder throw at both assigned weights compared with the shoulder press.

Methodology and Implications of Maximum Paleodischarge Estimates for

USGS Publications Warehouse

Channels, M.; Pruess, J.; Wohl, E.E.; Jarrett, R.D.

1998-01-01

Historical and geologic records may be used to enhance magnitude estimates for extreme floods along mountain channels, as demonstrated in this study from the San Juan Mountains of Colorado. Historical photographs and local newspaper accounts from the October 1911 flood indicate the likely extent of flooding and damage. A checklist designed to organize and numerically score evidence of flooding was used in 15 field reconnaissance surveys in the upper Animas River valley of southwestern Colorado. Step-backwater flow modeling estimated the discharges necessary to create longitudinal flood bars observed at 6 additional field sites. According to these analyses, maximum unit discharge peaks at approximately 1.3 m3 s~' km"2 around 2200 m elevation, with decreased unit discharges at both higher and lower elevations. These results (1) are consistent with Jarrett's (1987, 1990, 1993) maximum 2300-m elevation limit for flash-flooding in the Colorado Rocky Mountains, and (2) suggest that current Probable Maximum Flood (PMF) estimates based on a 24-h rainfall of 30 cm at elevations above 2700 m are unrealistically large. The methodology used for this study should be readily applicable to other mountain regions where systematic streamflow records are of short duration or nonexistent. ?? 1998 Regents of the University of Colorado.

CEDAR-GEM Challenge for Systematic Assessment of Ionosphere/Thermosphere Models in Predicting TEC During the 2006 December Storm Event

NASA Astrophysics Data System (ADS)

Shim, J. S.; Rastätter, L.; Kuznetsova, M.; Bilitza, D.; Codrescu, M.; Coster, A. J.; Emery, B. A.; Fedrizzi, M.; Förster, M.; Fuller-Rowell, T. J.; Gardner, L. C.; Goncharenko, L.; Huba, J.; McDonald, S. E.; Mannucci, A. J.; Namgaladze, A. A.; Pi, X.; Prokhorov, B. E.; Ridley, A. J.; Scherliess, L.; Schunk, R. W.; Sojka, J. J.; Zhu, L.

2017-10-01

In order to assess current modeling capability of reproducing storm impacts on total electron content (TEC), we considered quantities such as TEC, TEC changes compared to quiet time values, and the maximum value of the TEC and TEC changes during a storm. We compared the quantities obtained from ionospheric models against ground-based GPS TEC measurements during the 2006 AGU storm event (14-15 December 2006) in the selected eight longitude sectors. We used 15 simulations obtained from eight ionospheric models, including empirical, physics-based, coupled ionosphere-thermosphere, and data assimilation models. To quantitatively evaluate performance of the models in TEC prediction during the storm, we calculated skill scores such as RMS error, Normalized RMS error (NRMSE), ratio of the modeled to observed maximum increase (Yield), and the difference between the modeled peak time and observed peak time. Furthermore, to investigate latitudinal dependence of the performance of the models, the skill scores were calculated for five latitude regions. Our study shows that RMSE of TEC and TEC changes of the model simulations range from about 3 TECU (total electron content unit, 1 TECU = 1016 el m-2) (in high latitudes) to about 13 TECU (in low latitudes), which is larger than latitudinal average GPS TEC error of about 2 TECU. Most model simulations predict TEC better than TEC changes in terms of NRMSE and the difference in peak time, while the opposite holds true in terms of Yield. Model performance strongly depends on the quantities considered, the type of metrics used, and the latitude considered.

Effects of shoe cleat position on physiology and performance of competitive cyclists.

PubMed

Paton, Carl D

2009-12-01

Aerobic economy is an important factor that affects the performance of competitive cyclists. It has been suggested that placing the foot more anteriorly on the bicycle pedals may improve economy over the traditional foot position by improving pedaling efficiency. The current study examines the effects of changing the anterior-posterior pedal foot position on the physiology and performance of well-trained cyclists. In a crossover study, 10 competitive cyclists completed two maximal incremental and two submaximal tests in either their preferred (control) or a forward (arch) foot position. Maximum oxygen consumption and peak power output were determined from the incremental tests for both foot positions. On two further occasions, cyclists also completed a two-part 60-min submaximal test that required them to maintain a constant power output (equivalent to 60% of their incremental peak power) for 30 min, during which respiratory and blood lactate samples were taken at predetermined intervals. Thereafter, subjects completed a 30-min self-paced maximal effort time trial. Relative to the control, the mean changes (+/-90% confidence limits) in the arch condition were as follows: maximum oxygen consumption, -0.5% (+/-2.0%); incremental peak power output, -0.8% (+/-1.3%); steady-state oxygen consumption at 60%, -2.4% (+/-1.1%); steady-state heart rate 60%, 0.4% (+/-1.7%); lactate concentration 60%, 8.7% (+/-14.4%); and mean time trial power, -1.5% (+/-2.9%). We conclude that there was no substantial physiological or performance advantage in this group using an arch-cleat shoe position in comparison with a cyclist's normal preferred condition.

Running with a minimalist shoe increases plantar pressure in the forefoot region of healthy female runners.

PubMed

Bergstra, S A; Kluitenberg, B; Dekker, R; Bredeweg, S W; Postema, K; Van den Heuvel, E R; Hijmans, J M; Sobhani, S

2015-07-01

Minimalist running shoes have been proposed as an alternative to barefoot running. However, several studies have reported cases of forefoot stress fractures after switching from standard to minimalist shoes. Therefore, the aim of the current study was to investigate the differences in plantar pressure in the forefoot region between running with a minimalist shoe and running with a standard shoe in healthy female runners during overground running. Randomized crossover design. In-shoe plantar pressure measurements were recorded from eighteen healthy female runners. Peak pressure, maximum mean pressure, pressure time integral and instant of peak pressure were assessed for seven foot areas. Force time integral, stride time, stance time, swing time, shoe comfort and landing type were assessed for both shoe types. A linear mixed model was used to analyze the data. Peak pressure and maximum mean pressure were higher in the medial forefoot (respectively 13.5% and 7.46%), central forefoot (respectively 37.5% and 29.2%) and lateral forefoot (respectively 37.9% and 20.4%) for the minimalist shoe condition. Stance time was reduced with 3.81%. No relevant differences in shoe comfort or landing strategy were found. Running with a minimalist shoe increased plantar pressure without a change in landing pattern. This increased pressure in the forefoot region might play a role in the occurrence of metatarsal stress fractures in runners who switched to minimalist shoes and warrants a cautious approach to transitioning to minimalist shoe use. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Development of 600 kV triple resonance pulse transformer.

PubMed

Li, Mingjia; Zhang, Faqiang; Liang, Chuan; Xu, Zhou

2015-06-01

In this paper, a triple-resonance pulse transformer based on an air-core transformer is introduced. The voltage across the high-voltage winding of the air-core transformer is significantly less than the output voltage; instead, the full output voltage appears across the tuning inductor. The maximum ratio of peak load voltage to peak transformer voltage is 2.77 in theory. By analyzing pulse transformer's lossless circuit, the analytical expression for the output voltage and the characteristic equation of the triple-resonance circuit are presented. Design method for the triple-resonance pulse transformer (iterated simulation method) is presented, and a triple-resonance pulse transformer is developed based on the existing air-core transformer. The experimental results indicate that the maximum ratio of peak voltage across the load to peak voltage across the high-voltage winding of the air-core transformer is approximately 2.0 and the peak output voltage of the triple-resonance pulse transformer is approximately 600 kV.

Multiple current peaks in room-temperature atmospheric pressure homogenous dielectric barrier discharge plasma excited by high-voltage tunable nanosecond pulse in air

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

Yang, De-Zheng; Wang, Wen-Chun; Zhang, Shuai

2013-05-13

Room temperature homogenous dielectric barrier discharge plasma with high instantaneous energy efficiency is acquired by using nanosecond pulse voltage with 20-200 ns tunable pulse width. Increasing the voltage pulse width can lead to the generation of regular and stable multiple current peaks in each discharge sequence. When the voltage pulse width is 200 ns, more than 5 organized current peaks can be observed under 26 kV peak voltage. Investigation also shows that the organized multiple current peaks only appear in homogenous discharge mode. When the discharge is filament mode, organized multiple current peaks are replaced by chaotic filament current peaks.

A new approach for white organic light-emitting diodes of single emitting layer using large stokes shift.

PubMed

Kim, Beomjin; Park, Youngil; Kim, Seungho; Lee, Younggu; Park, Jongwook

2014-08-01

DPPZ showed UV-Vis. and PL maximum values of 412 and 638 nm, meaning the large stokes shift. Blue host compound, TAT was synthesized and used for co-mixed white emission. TAT exhibited UV-Vis. and PL maximum values of 403 nm and 445 nm in film state. Thus, when two compounds are used as co-mixed emitter in OLED device, there is no energy transfer from blue emission of TAT to DPPZ due to large stokes shift of DPPZ. Based on the PL result, it is available to realize two-colored white in PL and EL spectra. As a result of this, two-mixed compounds showed vivid their own PL emission peaks of 449 and 631 nm in film state. Also, white OLED device using two-mixed compounds system was fabricated. EL spectrum shows 457 and 634 nm peaks and two separate EL peaks, respectively. As the operation voltage is increased from 7 to 11 V, EL spectrum does not change the peak shape and maximum wavelength values. EL performance of white device showed 0.29 cd/A, 0.14 lm/W, and CIE (0.325, 0.195) at 7 V.

Body mass and antler development patterns of Rocky Mountain elk (Cervus elaphus nelsoni) in Michigan

USGS Publications Warehouse

Bender, L.C.; Carlson, E.; Schmitt, S.M.; Haufler, J.B.

2003-01-01

We documented mean and maximum body mass, mass accretion patterns and ander development patterns of Rocky Mountain elk in Michigan. Mean body mass of bulls averaged 9-11% heavier, and maximum body mass 23-27% heavier, in Michigan than in other Rocky Mountain elk populations. Mean live body mass of cows averaged 11% heavier in Michigan, but mean eviscerated body mass did not differ. Maximum body mass of cows was 10-24% heavier in Michigan. Body mass peaked at age 7.5 for bulls and 8.5 for cows, similar to other Rocky Mountain elk populations despite the greater body mass achieved in Michigan. Sexual dimorphism in bull and cow body mass increased until peak body mass was attained, whereupon bulls were ???38% heavier than cows. Antler development of bull elk peaked at age 10.5, comparable to other Rocky Mountain elk populations. Relations between antler development and body mass within age classes were highly variable, but generally weak. Greater body mass seen in Michigan, and the peaking of antler development well after body mass in bulls, suggested a phenotypic response to nutritional conditions that allow Rocky Mountain elk in Michigan to maximize the species growth potential.

Climate change is projected to have severe impacts on the frequency and intensity of peak electricity demand across the United States

PubMed Central

Auffhammer, Maximilian; Baylis, Patrick; Hausman, Catherine H.

2017-01-01

It has been suggested that climate change impacts on the electric sector will account for the majority of global economic damages by the end of the current century and beyond [Rose S, et al. (2014) Understanding the Social Cost of Carbon: A Technical Assessment]. The empirical literature has shown significant increases in climate-driven impacts on overall consumption, yet has not focused on the cost implications of the increased intensity and frequency of extreme events driving peak demand, which is the highest load observed in a period. We use comprehensive, high-frequency data at the level of load balancing authorities to parameterize the relationship between average or peak electricity demand and temperature for a major economy. Using statistical models, we analyze multiyear data from 166 load balancing authorities in the United States. We couple the estimated temperature response functions for total daily consumption and daily peak load with 18 downscaled global climate models (GCMs) to simulate climate change-driven impacts on both outcomes. We show moderate and heterogeneous changes in consumption, with an average increase of 2.8% by end of century. The results of our peak load simulations, however, suggest significant increases in the intensity and frequency of peak events throughout the United States, assuming today’s technology and electricity market fundamentals. As the electricity grid is built to endure maximum load, our findings have significant implications for the construction of costly peak generating capacity, suggesting additional peak capacity costs of up to 180 billion dollars by the end of the century under business-as-usual. PMID:28167756

Solution-processable red-emission organic materials containing triphenylamine and benzothiodiazole units: synthesis and applications in organic light-emitting diodes.

PubMed

Yang, Yi; Zhou, Yi; He, Qingguo; He, Chang; Yang, Chunhe; Bai, Fenglian; Li, Yongfang

2009-06-04

Three solution-processable red-emissive organic materials with a hole-transporting unit triphenylamine (TPA) as the core part and a D-pi-A bipolar structure as the branch part, TPA-BT (single-branched molecule), b-TPA-BT (bibranched molecule), and t-TPA-BT (tribranched molecule), were synthesized by the Heck coupling reaction. Herein, for the D-pi-A push-pull structure, we use TPA as the electron donor, benzothiodiazole (BT) as the electron acceptor, and the vinylene bond as the pi-bridge connecting the TPA and BT units. The compounds exhibit good solubility in common organic solvents, benefited from the three-dimensional spatial configuration of TPA units and the branch structure of the molecules. TPA-BT, b-TPA-BT, and t-TPA-BT show excellent photoluminescent properties with maximum emission peaks at ca. 630 nm. High-performance red-emission organic light-emitting diodes (OLEDs) were fabricated with the active layer spin coated from a solution of these compounds. The OLED based on TPA-BT displayed a low turn-on voltage of 2.0 V, a maximum luminance of 12192 cd/m2, and a maximum current efficiency of 1.66 cd/A, which is among the highest values for the solution-processed red-emission OLEDs. In addition, high-performance white-light-emitting diodes (WLEDs) with maximum luminance around 4400 cd/m2 and maximum current efficiencies above 4.5 cd/A were realized by separately doping the three TPA-BT-containing molecules as red emitter and poly(6,6'-bi-(9,9'-dihexylfluorene)- co-(9,9'-dihexylfluorene-3-thiophene-5'-yl)) as green emitter into blue poly(9,9-dioctylfluorene-2,7-diyl) host material with suitable weight ratios.

Lower Thoracic Spinal Cord Stimulation to Restore Cough in Patients with Spinal Cord Injury: Results of a National Institutes of Health-Sponsored Clinical Trial Part I: Methodology and Effectiveness of Expiratory Muscle Activation

PubMed Central

DiMarco, Anthony F.; Kowalski, Krzysztof E.; Geertman, Robert T.; Hromyak, Dana R.

2009-01-01

Objective Evaluation of the capacity of lower thoracic spinal cord stimulation (SCS) to activate the expiratory muscles and generate large airway pressures and high peak airflows characteristic of cough, in subjects with tetraplegia. Design Clinical trial. Setting In-patient hospital setting for electrode insertion; out-patient setting for measurement of respiratory pressures; home setting for application of SCS. Participants Subjects (N = 9; 8 men, 1 woman) with cervical spinal cord injury and weak cough. Intervention(s) A fully implantable electrical stimulation system was surgically placed in each subject. Partial hemilaminectomies were made to place single-disc electrodes in the epidural space at the T9, T11 and L1 spinal levels. A radiofrequency receiver was placed in the subcutaneous pocket over the anterior portion of the chest wall. Electrode wires were tunneled subcutaneously and connected to the receiver. Stimulation was applied by activating a small portable external stimulus controller box powered by a rechargeable battery to each electrode lead alone and in combination. Main Outcome Measure(s) Airway pressure and peak airflow generation achieved with SCS. Results Supramaximal SCS resulted in large airway pressures and high peak airflow rates during stimulation at each electrode lead. Maximum airway pressures and peak airflow rates were achieved with combined stimulation of any 2 leads. At total lung capacity, mean maximum airway pressure generation and peak airflow rates were 137 ± 30 cmH2O (mean ± SE) and 8.6 ± 1.8 (mean ± SE) L/s, respectively. Conclusions Lower thoracic SCS results in near maximum activation of the expiratory muscles and the generation of high positive airway pressures and peak airflow rates in the range of those observed with maximum cough efforts in normal individuals. PMID:19406289

Cardiorespiratory responses of a dance session designed for older women: A cross sectional study.

PubMed

Rodrigues-Krause, Josianne; Farinha, Juliano Boufleur; Ramis, Thiago Rozales; Boeno, Francesco Pinto; Dos Santos, Gabriela Cristina; Krause, Mauricio; Reischak-Oliveira, Alvaro

2018-06-04

Dancing has been increasingly used as a type of exercise intervention to improve cardiovascular fitness of older people. However, it is unclear which may be the exercise intensity of the dance sessions. To describe cardiorespiratory responses of a dance session for older women, and to identify intensity zones in relation to peak oxygen consumption (VO 2 peak), first and second ventilatory thresholds (VT1 and VT2). Ten women (66 ± 5 yrs., BMI 27 ± 4) were examined on three occasions: Familiarization, maximum effort and dance sessions. Incremental treadmill test: 5 km/h, 2% slope each min, until maximum effort. Dance class (60 min): warm-up (20 min), across-the-floor (10 min), choreography (15 min), show (10 min) and cool-down (5 min). Ventilatory parameters were measured continuously (breath-by-breath). VO 2 (mL·kg -1 ·min -1 ): Maximum effort: VO 2 peak (23.3 ± 4.3), VT1 (17.2 ± 3.5) and VT2 (20.9 ± 3.4). Dancing: warm-up (12.8 ± 2.4, ~55%VO 2 peak), across-the-floor (14.2 ± 2.4 ~62%VO 2 peak), choreography (14.6 ± 3.2 ~63%VO 2 peak) and show (16.1 ± 3.3, ~69% VO 2 peak). Show was similar to VT1. Cardiorespiratory demands of a dance class for older women are at low aerobic intensity. Show was similar to VT1, indicating that a dance class may be modulated to improve aerobic fitness, at least at initial stages of training. Copyright © 2018 Elsevier Inc. All rights reserved.

Simulations of cataclysmic outburst floods from Pleistocene Glacial Lake Missoula

USGS Publications Warehouse

Denlinger, Roger P.; O'Connell, D. R. H.

2009-01-01

Using a flow domain that we constructed from 30 m digital-elevation model data of western United States and Canada and a two-dimensional numerical model for shallow-water flow over rugged terrain, we simulated outburst floods from Pleistocene Glacial Lake Missoula. We modeled a large, but not the largest, flood, using initial lake elevation at 1250 m instead of 1285 m. Rupture of the ice dam, centered on modern Lake Pend Oreille, catastrophically floods eastern Washington and rapidly fills the broad Pasco, Yakima, and Umatilla Basins. Maximum flood stage is reached in Pasco and Yakima Basins 38 h after the dam break, whereas maximum flood stage in Umatilla Basin occurs 17 h later. Drainage of these basins through narrow Columbia gorge takes an additional 445 h. For this modeled flood, peak discharges in eastern Washington range from 10 to 20 × 106 m3/s. However, constrictions in Columbia gorge limit peak discharges to 6 m3/s and greatly extend the duration of flooding. We compare these model results with field observations of scabland distribution and high-water indicators. Our model predictions of the locations of maximum scour (product of bed shear stress and average flow velocity) match the distribution of existing scablands. We compare model peak stages to high-water indicators from the Rathdrum-Spokane valley, Walulla Gap, and along Columbia gorge. Though peak stages from this less-than-maximal flood model attain or exceed peak-stage indicators along Rathdrum-Spokane valley and along Columbia gorge, simulated peak stages near Walulla Gap are 10–40 m below observed peak-stage indicators. Despite this discrepancy, our match to field observations in most of the region indicates that additional sources of water other than Glacial Lake Missoula are not required to explain the Missoula floods.

Electron penetration of spacecraft thermal insulation

NASA Technical Reports Server (NTRS)

Powers, W. L.; Adams, B. F.; Inouye, G. T.

1981-01-01

The external thermal blanket with 13 mils of polyethylene which has the known range and stopping power as a function of electron energy is investiated. The most recent omnidirectional peak Jovian electron flux at 5 Jupiter radii is applied, the electron current penetrating the thermal blanket is calculated and allowed to impinge on a typical 20 mil polyethylene insulator surrounding a wire. The radiation dose rate to the insulator is then calculated and the electrical conductivity found. The results demonstrate that the increased electronic mobility is sufficient to keep the maximum induced electric field two orders of magnitude below the critical breakdown strength.

Efficiency optimization in a correlation ratchet with asymmetric unbiased fluctuations

NASA Astrophysics Data System (ADS)

Ai, Bao-Quan; Wang, Xian-Ju; Liu, Guo-Tao; Wen, De-Hua; Xie, Hui-Zhang; Chen, Wei; Liu, Liang-Gang

2003-12-01

The efficiency of a Brownian particle moving in a periodic potential in the presence of asymmetric unbiased fluctuations is investigated. We found that even on the quasistatic limit there is a regime where the efficiency can be a peaked function of temperature, which proves that thermal fluctuations facilitate the efficiency of energy transformation, contradicting the earlier findings [H. Kamegawa et al., Phys. Rev. Lett. 80, 5251 (1998)]. It is also found that the mutual interplay between temporal asymmetry and spatial asymmetry may induce optimized efficiency at finite temperatures. The ratchet is not most efficient when it gives maximum current.

Ozone uptake, water loss and carbon exchange dynamics in annually drought-stressed Pinus ponderosa forests: measured trends and parameters for uptake modeling.

PubMed

Panek, Jeanne A

2004-03-01

This paper describes 3 years of physiological measurements on ponderosa pine (Pinus ponderosa Dougl. ex Laws.) growing along an ozone concentration gradient in the Sierra Nevada, California, including variables necessary to parameterize, validate and modify photosynthesis and stomatal conductance algorithms used to estimate ozone uptake. At all sites, gas exchange was under tight stomatal control during the growing season. Stomatal conductance was strongly correlated with leaf water potential (R2=0.82), which decreased over the growing season with decreasing soil water content (R2=0.60). Ozone uptake, carbon uptake, and transpirational water loss closely followed the dynamics of stomatal conductance. Peak ozone and CO2 uptake occurred in early summer and declined progressively thereafter. As a result, periods of maximum ozone uptake did not correspond to periods of peak ozone concentration, underscoring the inappropriateness of using current metrics based on concentration (e.g., SUM0, W126 and AOT40) for assessing ozone exposure risk to plants in this climate region. Both Jmax (maximum CO2-saturated photosynthetic rate, limited by electron transport) and Vcmax (maximum rate of Rubisco-limited carboxylation) increased toward the middle of the growing season, then decreased in September. Intrinsic water-use efficiency rose with increasing drought stress, as expected. The ratio of Jmax to Vcmax was similar to literature values of 2.0. Nighttime respiration followed a Q10 of 2.0, but was significantly higher at the high-ozone site. Respiration rates decreased by the end of the summer as a result of decreased metabolic activity and carbon stores.

Flow and turbulence structure in a hypertidal estuary with the world's biggest tidal bore

NASA Astrophysics Data System (ADS)

Tu, Junbiao; Fan, Daidu

2017-04-01

Turbulent and flow structure associated with breaking tidal bores are deliberately investigated on the basis of field measurements. High-resolution velocity and hydrographic data are collected in the middle Qiantang Estuary by a vertical array of acoustic Doppler velocimeters and optical backscatter sensors, collaborated with a bottom-mounted acoustic Doppler current profiler. Besides obvious variations in diurnal and spring-neap tidal cycles, the estuarine dynamics is featured by extreme asymmetry in flood and ebb tides. The flood tide is abnormally accelerated to generate tidal bores at the first 10 min or more, with breaking or undular configurations at the front. The occurrence of peak flow velocity, turbulent kinetic energy (TKE), and TKE dissipation rate (ɛ) is definitely associated with breaking bores, with their values several times to 2 orders of magnitude larger than the corresponding secondary peak values during the maximum ebb flows. Flow and turbulence dynamics are significantly affected by the tidal-bore Froude number. A sandwich ɛ structure is clear exhibited with the maximum value at the surface, secondary maximum near the bed, and the minimum at the intermediate. Dual TKE sources are indicated by an approximate local balance between shear production and dissipation near the bottom, and a top-down TKE dissipation using the modified Froude scaling in the vertical water column. The highly elevated dissipation by breaking bores is comparable to that by intense breaking waves in the surf zone, and the former potentially penetrates the entire water column to produce extreme sediment-resuspension events in combination with intense bottom shear stress.

Method and apparatus for electrospark deposition

DOEpatents

Bailey, Jeffrey A.; Johnson, Roger N.; Park, Walter R.; Munley, John T.

2004-12-28

A method and apparatus for controlling electrospark deposition (ESD) comprises using electrical variable waveforms from the ESD process as a feedback parameter. The method comprises measuring a plurality of peak amplitudes from a series of electrical energy pulses delivered to an electrode tip. The maximum peak value from among the plurality of peak amplitudes correlates to the contact force between the electrode tip and a workpiece. The method further comprises comparing the maximum peak value to a set point to determine an offset and optimizing the contact force according to the value of the offset. The apparatus comprises an electrode tip connected to an electrical energy wave generator and an electrical signal sensor, which connects to a high-speed data acquisition card. An actuator provides relative motion between the electrode tip and a workpiece by receiving a feedback drive signal from a processor that is operably connected to the actuator and the high-speed data acquisition card.

Effects of squat lift training and free weight muscle training on maximum lifting load and isolinetic peak torque of young adults without impairments.

PubMed

Yeung, S S; Ng, G Y

2000-06-01

Manual lifting is a frequent cause of back injury, and there is no evidence as to which training mode can provide the best training effect for lifting performance and muscle force. The purpose of this study was to examine the effects of a squat lift training and a free weight muscle training program on the maximum lifting load and isokinetic peak torque in subjects without known neuromuscular or musculoskeletal impairments. Thirty-six adults (20 male, 16 female) without known neuromuscular or musculoskeletal impairments participated. The subjects' mean age was 21.25 years (SD=1.16, range=20-24). Subjects were divided into 3 groups. Subjects in group 1 (n=12) performed squat lift training. Subjects in group 2 (n=12) participated in free weight resistance training of their shoulder abductors, elbow flexors, knee extensors and trunk extensors. Subjects in group 3 (n=12) served as controls. The maximum lifting load and isokinetic peak torques of the trunk extensors, knee extensors, elbow flexors, and shoulder abductors of each subject were measured before and after the study. Training was conducted on alternate days for 4 weeks, with an initial load of 80% of each subject's maximum capacity and with the load increased by 5% weekly. All groups were comparable for all measured variables before the study. After 4 weeks, subjects in groups 1 and 2 demonstrated more improvement in maximum lifting load and isokinetic peak torque of the back extensors compared with the subjects in group 3, but the 2 training groups were not different. The findings demonstrate that both squat lift and free weight resistance training are equally effective in improving the lifting load and isokinetic back extension performance of individuals without impairments.

Performance Study of Earth Networks Total Lightning Network using Rocket-Triggered Lightning Data in 2014

NASA Astrophysics Data System (ADS)

Heckman, S.

2015-12-01

Modern lightning locating systems (LLS) provide real-time monitoring and early warning of lightningactivities. In addition, LLS provide valuable data for statistical analysis in lightning research. It isimportant to know the performance of such LLS. In the present study, the performance of the EarthNetworks Total Lightning Network (ENTLN) is studied using rocket-triggered lightning data acquired atthe International Center for Lightning Research and Testing (ICLRT), Camp Blanding, Florida.In the present study, 18 flashes triggered at ICLRT in 2014 were analyzed and they comprise of 78negative cloud-to-ground return strokes. The geometric mean, median, minimum, and maximum for thepeak currents of the 78 return strokes are 13.4 kA, 13.6 kA, 3.7 kA, and 38.4 kA, respectively. The peakcurrents represent typical subsequent return strokes in natural cloud-to-ground lightning.Earth Networks has developed a new data processor to improve the performance of their network. Inthis study, results are presented for the ENTLN data using the old processor (originally reported in 2014)and the ENTLN data simulated using the new processor. The flash detection efficiency, stroke detectionefficiency, percentage of misclassification, median location error, median peak current estimation error,and median absolute peak current estimation error for the originally reported data from old processorare 100%, 94%, 49%, 271 m, 5%, and 13%, respectively, and those for the simulated data using the newprocessor are 100%, 99%, 9%, 280 m, 11%, and 15%, respectively. The use of new processor resulted inhigher stroke detection efficiency and lower percentage of misclassification. It is worth noting that theslight differences in median location error, median peak current estimation error, and median absolutepeak current estimation error for the two processors are due to the fact that the new processordetected more number of return strokes than the old processor.

A brief review of strength and ballistic assessment methodologies in sport.

PubMed

McMaster, Daniel Travis; Gill, Nicholas; Cronin, John; McGuigan, Michael

2014-05-01

An athletic profile should encompass the physiological, biomechanical, anthropometric and performance measures pertinent to the athlete's sport and discipline. The measurement systems and procedures used to create these profiles are constantly evolving and becoming more precise and practical. This is a review of strength and ballistic assessment methodologies used in sport, a critique of current maximum strength [one-repetition maximum (1RM) and isometric strength] and ballistic performance (bench throw and jump capabilities) assessments for the purpose of informing practitioners and evolving current assessment methodologies. The reliability of the various maximum strength and ballistic assessment methodologies were reported in the form of intra-class correlation coefficients (ICC) and coefficient of variation (%CV). Mean percent differences (Mdiff = [/Xmethod1 - Xmethod2/ / (Xmethod1 + Xmethod2)] x 100) and effect size (ES = [Xmethod2 - Xmethod1] ÷ SDmethod1) calculations were used to assess the magnitude and spread of methodological differences for a given performance measure of the included studies. Studies were grouped and compared according to their respective performance measure and movement pattern. The various measurement systems (e.g., force plates, position transducers, accelerometers, jump mats, optical motion sensors and jump-and-reach apparatuses) and assessment procedures (i.e., warm-up strategies, loading schemes and rest periods) currently used to assess maximum isometric squat and mid-thigh pull strength (ICC > 0.95; CV < 2.0%), 1RM bench press, back squat and clean strength (ICC > 0.91; CV < 4.3%), and ballistic (vertical jump and bench throw) capabilities (ICC > 0.82; CV < 6.5%) were deemed highly reliable. The measurement systems and assessment procedures employed to assess maximum isometric strength [M(Diff) = 2-71%; effect size (ES) = 0.13-4.37], 1RM strength (M(Diff) = 1-58%; ES = 0.01-5.43), vertical jump capabilities (M(Diff) = 2-57%; ES = 0.02-4.67) and bench throw capabilities (M(Diff) = 7-27%; ES = 0.49-2.77) varied greatly, producing trivial to very large effects on these respective measures. Recreational to highly trained athletes produced maximum isometric squat and mid-thigh pull forces of 1,000-4,000 N; and 1RM bench press, back squat and power clean values of 80-180 kg, 100-260 kg and 70-140 kg, respectively. Mean and peak power production across the various loads (body mass to 60% 1RM) were between 300 and 1,500 W during the bench throw and between 1,500 and 9,000 W during the vertical jump. The large variations in maximum strength and power can be attributed to the wide range in physical characteristics between different sports and athletic disciplines, training and chronological age as well as the different measurement systems of the included studies. The reliability and validity outcomes suggest that a number of measurement systems and testing procedures can be implemented to accurately assess maximum strength and ballistic performance in recreational and elite athletes, alike. However, the reader needs to be cognisant of the inherent differences between measurement systems, as selection will inevitably affect the outcome measure. The strength and conditioning practitioner should also carefully consider the benefits and limitations of the different measurement systems, testing apparatuses, attachment sites, movement patterns (e.g., direction of movement, contraction type, depth), loading parameters (e.g., no load, single load, absolute load, relative load, incremental loading), warm-up strategies, inter-trial rest periods, dependent variables of interest (i.e., mean, peak and rate dependent variables) and data collection and processing techniques (i.e., sampling frequency, filtering and smoothing options).

[Caloric value and energy allocation of Chloris virgata in northeast grassland].

PubMed

Guo, J; Wang, R; Wang, W

2001-06-01

The rules of seasonal changes in caloric values of individual plant, stem, and leaves of Chloris virgata were similar, which had two peak values from early July to early August, and then decreased gradually. Those of inflorescence assumed U shape, and had two peak values in early August and middle September, respectively. The seasonal changes in caloric values of dead standing were irregular, and the maximum value was appeared in early August. The seasonal changes in existent energy value of the aboveground parts in Chloris virgata population presented double peak curve. The two peak values were appeared in early August and early September respectively, and the maximum value was 7381.27 kJ.m-2 in early September. The energy allocation in different seasons was leaf > stem in early July, stem > leaf > dead standing in middle July, stem > leaf > inflorescence > dead standing in August, stem > inflorescence > leaf > dead standing in early September, and stem > inflorescence > dead standing > leaf in middle September. The vertical structure of energy in the aboveground parts was that the energy value gradually increased from the earth's surface to 20 cm high, and then decreased. The maximum value, which accounted for 25.75% of energy in the aboveground parts, was appeared in the layer of 10-20 cm high. In the underground parts, the energy value progressively decreased with the increase of depth, and the maximum value, which accounted for 74.21% of energy in the underground parts, was appeared in the layer of 0-10 cm depth.

Prognostic value of metabolic metrics extracted from baseline PET images in NSCLC

PubMed Central

Carvalho, Sara; Leijenaar, Ralph T.H.; Velazquez, Emmanuel Rios; Oberije, Cary; Parmar, Chintan; van Elmpt, Wouter; Reymen, Bart; Troost, Esther G.C.; Oellers, Michel; Dekker, Andre; Gillies, Robert; Aerts, Hugo J.W.L.; Lambin, Philippe

2015-01-01

Background Maximum, mean and peak SUV of primary tumor at baseline FDG-PET scans, have often been found predictive for overall survival in non-small cell lung cancer (NSCLC) patients. In this study we further investigated the prognostic power of advanced metabolic metrics derived from Intensity-Volume Histograms (IVH) extracted from PET imaging. Methods A cohort of 220 NSCLC patients (mean age, 66.6 years; 149 men, 71 women), stages I-IIIB, treated with radiotherapy with curative intent were included (NCT00522639). Each patient underwent standardized pre-treatment CT-PET imaging. Primary GTV was delineated by an experienced radiation oncologist on CT-PET images. Common PET descriptors such as maximum, mean and peak SUV, and metabolic tumor volume (MTV) were quantified. Advanced descriptors of metabolic activity were quantified by IVH. These comprised 5 groups of features: Absolute and Relative Volume above Relative Intensity threshold (AVRI and RVRI), Absolute and Relative Volume above Absolute Intensity threshold (AVAI and RVAI), and Absolute Intensity above Relative Volume threshold (AIRV). MTV was derived from the IVH curves for volumes with SUV above 2.5, 3 and 4, and of 40% and 50% maximum SUV. Univariable analysis using Cox Proportional Hazard Regression was performed for overall survival assessment. Results Relative volume above higher SUV (80 %) was an independent predictor of OS (p = 0.05). None of the possible surrogates for MTV based on volumes above SUV of 3, 40% and 50% of maximum SUV showed significant associations with OS (p (AVAI3) = 0.10, p (AVAI4) = 0.22, p (AVRI40%) = 0.15, p (AVRI50%) = 0.17). Maximum and peak SUV (r = 0.99) revealed no prognostic value for OS (p (maximum SUV) = 0.20, p (peak SUV) = 0.22). Conclusions New methods using more advanced imaging features extracted from PET were analyzed. Best prognostic value for OS of NSCLC patients was found for relative portions of the tumor above higher uptakes (80% SUV). PMID:24047338

Limitations to maximum running speed on flat curves.

PubMed

Chang, Young-Hui; Kram, Rodger

2007-03-01

Why is maximal running speed reduced on curved paths? The leading explanation proposes that an increase in lateral ground reaction force necessitates a decrease in peak vertical ground reaction force, assuming that maximum leg extension force is the limiting factor. Yet, no studies have directly measured these forces or tested this critical assumption. We measured maximum sprint velocities and ground reaction forces for five male humans sprinting along a straight track and compared them to sprints along circular tracks of 1, 2, 3, 4 and 6 m radii. Circular track sprint trials were performed either with or without a tether that applied centripetal force to the center of mass. Sprinters generated significantly smaller peak resultant ground reaction forces during normal curve sprinting compared to straight sprinting. This provides direct evidence against the idea that maximum leg extension force is always achieved and is the limiting factor. Use of the tether increased sprint speed, but not to expected values. During curve sprinting, the inside leg consistently generated smaller peak forces compared to the outside leg. Several competing biomechanical constraints placed on the stance leg during curve sprinting likely make the inside leg particularly ineffective at generating the ground reaction forces necessary to attain maximum velocities comparable to straight path sprinting. The ability of quadrupeds to redistribute function across multiple stance legs and decouple these multiple constraints may provide a distinct advantage for turning performance.

Pulsed characterization of a UV LED for pulsed power applications on a silicon carbide photoconductive semiconductor switch

NASA Astrophysics Data System (ADS)

Wilson, Nicholas; Mauch, Daniel; Meyers, Vincent; Feathers, Shannon; Dickens, James; Neuber, Andreas

2017-08-01

The electrical and optical characteristics of a high-power UV light emitting diode (LED) (365 nm wavelength) were evaluated under pulsed operating conditions at current amplitudes several orders of magnitude beyond the LED's manufacturer specifications. Geared towards triggering of photoconductive semiconductor switches (PCSSs) for pulsed power applications, measurements were made over varying pulse widths (25 ns-100 μs), current (0 A-250 A), and repetition rates (single shot-5 MHz). The LED forward voltage was observed to increase linearly with increasing current (˜3.5 V-53 V) and decrease with increasing pulse widths. The peak optical power observed was >30 W, and a maximum system efficiency of 23% was achieved. The evaluated LED and auxiliary hardware were successfully used as the optical trigger source for a 4H-SiC PCSS. The lowest measured on-resistance of SiC was approximately 67 kΩ.

Pulsed characterization of a UV LED for pulsed power applications on a silicon carbide photoconductive semiconductor switch.

PubMed

Wilson, Nicholas; Mauch, Daniel; Meyers, Vincent; Feathers, Shannon; Dickens, James; Neuber, Andreas

2017-08-01

The electrical and optical characteristics of a high-power UV light emitting diode (LED) (365 nm wavelength) were evaluated under pulsed operating conditions at current amplitudes several orders of magnitude beyond the LED's manufacturer specifications. Geared towards triggering of photoconductive semiconductor switches (PCSSs) for pulsed power applications, measurements were made over varying pulse widths (25 ns-100 μs), current (0 A-250 A), and repetition rates (single shot-5 MHz). The LED forward voltage was observed to increase linearly with increasing current (∼3.5 V-53 V) and decrease with increasing pulse widths. The peak optical power observed was >30 W, and a maximum system efficiency of 23% was achieved. The evaluated LED and auxiliary hardware were successfully used as the optical trigger source for a 4H-SiC PCSS. The lowest measured on-resistance of SiC was approximately 67 kΩ.

Phonons in Confinement and the Boson Peak Using Nuclear Inelastic Absorption

NASA Astrophysics Data System (ADS)

Asthalter, T.; Bauer, M.; van Bürck, U.; Sergueev, I.; Franz, H.; Chumakov, A. I.

2002-12-01

We have applied nuclear inelastic absorption (NIA) to the molecular glass former dibutylphthalate/ferrocene, both in bulk and in nanoporous matrices having pore sizes of 50 and 25 Å, respectively. The quantity g(E)/E 2, where g(E) is the vibrational phonon density of states (VDOS) of the resonant nuclei, exhibits a pronounced maximum at low energies. Confinement in pores leads to a suppression of the VDOS below 1.5 meV, independent of the pore size. Also in the scaled heat capacity C(T)/T 3, we observe a decrease of the peak maximum for low temperatures. Our observations are discussed in the light of experimental and theoretical results on nanocrystals and a recent theoretical model for the boson peak.

Generation of High-Power High-Intensity Short X-Ray Free-Electron-Laser Pulses

DOE PAGES

Guetg, Marc W.; Lutman, Alberto A.; Ding, Yuantao; ...

2018-01-03

X-ray free-electron lasers combine a high pulse power, short pulse length, narrow bandwidth, and high degree of transverse coherence. Any increase in the photon pulse power, while shortening the pulse length, will further push the frontier on several key x-ray free-electron laser applications including single-molecule imaging and novel nonlinear x-ray methods. This Letter shows experimental results at the Linac Coherent Light Source raising its maximum power to more than 300% of the current limit while reducing the photon pulse length to 10 fs. As a result, this was achieved by minimizing residual transverse-longitudinal centroid beam offsets and beam yaw andmore » by correcting the dispersion when operating over 6 kA peak current with a longitudinally shaped beam.« less

Generation of High-Power High-Intensity Short X-Ray Free-Electron-Laser Pulses

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

Guetg, Marc W.; Lutman, Alberto A.; Ding, Yuantao

X-ray free-electron lasers combine a high pulse power, short pulse length, narrow bandwidth, and high degree of transverse coherence. Any increase in the photon pulse power, while shortening the pulse length, will further push the frontier on several key x-ray free-electron laser applications including single-molecule imaging and novel nonlinear x-ray methods. This Letter shows experimental results at the Linac Coherent Light Source raising its maximum power to more than 300% of the current limit while reducing the photon pulse length to 10 fs. As a result, this was achieved by minimizing residual transverse-longitudinal centroid beam offsets and beam yaw andmore » by correcting the dispersion when operating over 6 kA peak current with a longitudinally shaped beam.« less

Tidal asymmetries of velocity and stratification over a bathymetric depression in a tropical inlet

NASA Astrophysics Data System (ADS)

Waterhouse, Amy F.; Valle-Levinson, Arnoldo; Morales Pérez, Rubén A.

2012-10-01

Observations of current velocity, sea surface elevation and vertical profiles of density were obtained in a tropical inlet to determine the effect of a bathymetric depression (hollow) on the tidal flows. Surveys measuring velocity profiles were conducted over a diurnal tidal cycle with mixed spring tides during dry and wet seasons. Depth-averaged tidal velocities during ebb and flood tides behaved according to Bernoulli dynamics, as expected. The dynamic balance of depth-averaged quantities in the along-channel direction was governed by along-channel advection and pressure gradients with baroclinic pressure gradients only being important during the wet season. The vertical structure of the along-channel flow during flood tides exhibited a mid-depth maximum with lateral shear enhanced during the dry season as a result of decreased vertical stratification. During ebb tides, along-channel velocities in the vicinity of the hollow were vertically sheared with a weak return flow at depth due to choking of the flow on the seaward slope of the hollow. The potential energy anomaly, a measure of the amount of energy required to fully mix the water column, showed two peaks in stratification associated with ebb tide and a third peak occurring at the beginning of flood. After the first mid-ebb peak in stratification, ebb flows were constricted on the seaward slope of the hollow resulting in a bottom return flow. The sinking of surface waters and enhanced mixing on the seaward slope of the hollow reduced the potential energy anomaly after maximum ebb. The third peak in stratification during early flood occurred as a result of denser water entering the inlet at mid-depth. This dense water mixed with ambient deep waters increasing the stratification. Lateral shear in the along-channel flow across the hollow allowed trapping of less dense water in the surface layers further increasing stratification.

Changes in patellofemoral pain resulting from repetitive impact landings are associated with the magnitude and rate of patellofemoral joint loading.

PubMed

Atkins, Lee T; James, C Roger; Yang, Hyung Suk; Sizer, Phillip S; Brismée, Jean-Michel; Sawyer, Steven F; Powers, Christopher M

2018-03-01

Although a relationship between elevated patellofemoral forces and pain has been proposed, it is unknown which joint loading variable (magnitude, rate) is best associated with pain changes. The purpose of this study was to examine associations among patellofemoral joint loading variables and changes in patellofemoral pain across repeated single limb landings. Thirty-one females (age: 23.5(2.8) year; height: 166.8(5.8) cm; mass: 59.6(8.1) kg) with PFP performed 5 landing trials from 0.25 m. The dependent variable was rate of change in pain obtained from self-reported pain scores following each trial. Independent variables included 5-trial averages of peak, time-integral, and average and maximum development rates of the patellofemoral joint reaction force obtained using a previously described model. Pearson correlation coefficients were calculated to evaluate individual associations between rate of change in pain and each independent variable (α = 0.05). Stepwise linear multiple regression (α enter  = 0.05; α exit  = 0.10) was used to identify the best predictor of rate of change in pain. Subjects reported an average increase of 0.38 pain points with each landing trial. Although, rate of change in pain was positively correlated with peak force (r = 0.44, p = 0.01), and average (r = 0.41, p = 0.02) and maximum force development rates (r = 0.39, p = 0.03), only the peak force entered the predictive model explaining 19% of variance in rate of change in pain (r 2  = 0.19, p = 0.01). Peak patellofemoral joint reaction force was the best predictor of the rate of change in pain following repetitive singe limb landings. The current study supports the theory that patellofemoral joint loading contributes to changes in patellofemoral pain. Copyright © 2018 Elsevier Ltd. All rights reserved.

Proton transport polarization and depolarization of hydroxyapatite ceramics

NASA Astrophysics Data System (ADS)

Nakamura, Satoshi; Takeda, Hiroaki; Yamashita, Kimihiro

2001-05-01

Polarization of sintered hydroxyapatite (HAp) ceramics by application of an external dc field at higher temperature was analyzed by thermally stimulated depolarization current (TSDC) measurements. The mechanisms for the polarization and depolarization of HAp were discussed in relation to the instability of the protons in the hydroxide groups. The TSDC spectra consisted of broad peaks, while the ferroelectric substances such as the BaTiO3 ceramics exhibited a sharp peak. Although the maximum current density of 7.87 nA cm-2 for the HAp polarized at 400 °C under 1.0 kV cm-1 was approximately 1/12 lower than that of BaTiO3, the polarization charge of 14.9 μC cm-2 was almost twice as large as that of BaTiO3. Considering the activation energy of 0.72-0.89 eV for the depolarization, it was revealed that the polarization of HAp was ascribed to the migration of protons in the columnar OH- channels with a micrometer-order distance. It was also found that the polarization charge was large and long enough to enhance the biological reactivity of HAp ceramics for biomedical implants.

High sensitivity field asymmetric ion mobility spectrometer

NASA Astrophysics Data System (ADS)

Chavarria, Mario A.; Matheoud, Alessandro V.; Marmillod, Philippe; Liu, Youjiang; Kong, Deyi; Brugger, Jürgen; Boero, Giovanni

2017-03-01

A high sensitivity field asymmetric ion mobility spectrometer (FAIMS) was designed, fabricated, and tested. The main components of the system are a 10.6 eV UV photoionization source, an ion filter driven by a high voltage/high frequency n-MOS inverter circuit, and a low noise ion detector. The ion filter electronics are capable to generate square waveforms with peak-to-peak voltages up to 1000 V at frequencies up to 1 MHz with adjustable duty cycles. The ion detector current amplifier has a gain up to 1012 V/A with an effective equivalent input noise level down to about 1 fA/Hz1/2 during operation with the ion filter at the maximum voltage and frequency. The FAIMS system was characterized by detecting different standard chemical compounds. Additionally, we investigated the use of a synchronous modulation/demodulation technique to improve the signal-to-noise ratio in FAIMS measurements. In particular, we implemented the modulation of the compensation voltage with the synchronous demodulation of the ion current. The analysis of the measurements at low concentration levels led to an extrapolated limit of detection for acetone of 10 ppt with an averaging time of 1 s.

The use of distributed hydrological models for the Gard 2002 flash flood event: Analysis of associated hydrological processes

NASA Astrophysics Data System (ADS)

Braud, Isabelle; Roux, Hélène; Anquetin, Sandrine; Maubourguet, Marie-Madeleine; Manus, Claire; Viallet, Pierre; Dartus, Denis

2010-11-01

SummaryThis paper presents a detailed analysis of the September 8-9, 2002 flash flood event in the Gard region (southern France) using two distributed hydrological models: CVN built within the LIQUID® hydrological platform and MARINE. The models differ in terms of spatial discretization, infiltration and water redistribution representation, and river flow transfer. MARINE can also account for subsurface lateral flow. Both models are set up using the same available information, namely a DEM and a pedology map. They are forced with high resolution radar rainfall data over a set of 18 sub-catchments ranging from 2.5 to 99 km2 and are run without calibration. To begin with, models simulations are assessed against post field estimates of the time of peak and the maximum peak discharge showing a fair agreement for both models. The results are then discussed in terms of flow dynamics, runoff coefficients and soil saturation dynamics. The contribution of the subsurface lateral flow is also quantified using the MARINE model. This analysis highlights that rainfall remains the first controlling factor of flash flood dynamics. High rainfall peak intensities are very influential of the maximum peak discharge for both models, but especially for the CVN model which has a simplified overland flow transfer. The river bed roughness also influences the peak intensity and time. Soil spatial representation is shown to have a significant role on runoff coefficients and on the spatial variability of saturation dynamics. Simulated soil saturation is found to be strongly related with soil depth and initial storage deficit maps, due to a full saturation of most of the area at the end of the event. When activated, the signature of subsurface lateral flow is also visible in the spatial patterns of soil saturation with higher values concentrating along the river network. However, the data currently available do not allow the assessment of both patterns. The paper concludes with a set of recommendations for enhancing field observations in order to progress in process understanding and gather a larger set of data to improve the realism of distributed models.

Memory Effect Manifested by a Boson Peak in Metallic Glass.

PubMed

Luo, P; Li, Y Z; Bai, H Y; Wen, P; Wang, W H

2016-04-29

We explore the correlation between a boson peak and structural relaxation in a typical metallic glass. Consistent with enthalpy recovery, a boson peak shows a memory effect in an aging-and-scan procedure. Single-step isothermal aging produces a monotonic decrease of enthalpy and boson peak intensity; for double-step isothermal aging, both enthalpy and boson peak intensity experience, coincidently, an incipient increase to a maximum and a subsequent decrease toward the equilibrium state. Our results indicate a direct link between slow structural relaxation and fast boson peak dynamics, which presents a profound understanding of the two dynamic behaviors in glass.

Variability of the occurrence frequency of solar flares as a function of peak hard X-ray rate

NASA Technical Reports Server (NTRS)

Bai, T.

1993-01-01

We study the occurrence frequency of solar flares as a function of the hard X-ray peak count rate, using observations of the Solar Maximum Mission. The size distributions are well represented by power-law distributions with negative indices. As a better alternative to the conventional method, we devise a maximum likelihood method of determining the power-law index of the size distribution. We find that the power-law index of the size distribution changes with time and with the phase of the 154-day periodicity. The size distribution is steeper during the maximum years of solar cycle 21 (1980 and 1981) than during the declining phase (1982-1984). The size distribution, however, is flatter during the maximum phase of the 154-day periodicity than during the minimum phase. The implications of these findings are discussed.

Enhanced light out-coupling efficiency of organic light-emitting diodes with an extremely low haze by plasma treated nanoscale corrugation

NASA Astrophysics Data System (ADS)

Hwang, Ju Hyun; Lee, Hyun Jun; Shim, Yong Sub; Park, Cheol Hwee; Jung, Sun-Gyu; Kim, Kyu Nyun; Park, Young Wook; Ju, Byeong-Kwon

2015-01-01

Extremely low-haze light extraction from organic light-emitting diodes (OLEDs) was achieved by utilizing nanoscale corrugation, which was simply fabricated with plasma treatment and sonication. The haze of the nanoscale corrugation for light extraction (NCLE) corresponds to 0.21% for visible wavelengths, which is comparable to that of bare glass. The OLEDs with NCLE showed enhancements of 34.19% in current efficiency and 35.75% in power efficiency. Furthermore, the OLEDs with NCLE exhibited angle-stable electroluminescence (EL) spectra for different viewing angles, with no change in the full width at half maximum (FWHM) and peak wavelength. The flexibility of the polymer used for the NCLE and plasma treatment process indicates that the NCLE can be applied to large and flexible OLED displays.Extremely low-haze light extraction from organic light-emitting diodes (OLEDs) was achieved by utilizing nanoscale corrugation, which was simply fabricated with plasma treatment and sonication. The haze of the nanoscale corrugation for light extraction (NCLE) corresponds to 0.21% for visible wavelengths, which is comparable to that of bare glass. The OLEDs with NCLE showed enhancements of 34.19% in current efficiency and 35.75% in power efficiency. Furthermore, the OLEDs with NCLE exhibited angle-stable electroluminescence (EL) spectra for different viewing angles, with no change in the full width at half maximum (FWHM) and peak wavelength. The flexibility of the polymer used for the NCLE and plasma treatment process indicates that the NCLE can be applied to large and flexible OLED displays. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06547f

The Canary Basin contribution to 26ºN AMOC Seasonality

NASA Astrophysics Data System (ADS)

Pérez-Hernández, M. D.; McCarthy, G.; Smeed, D.; Hernandez-Guerra, A.; Vélez-Belchí, P.

2014-12-01

Recent studies have shown that the seasonal transport of the Atlantic Meridional Overturning Circulation (AMOC) is linked with seasonal density changes in the eastern boundary of the Atlantic. As measured by the RAPID/MOCHA array, the AMOC has a seasonal peak-to-peak value of 6 Sv, with two relative maximums in July and October. The relative maximum in October coincides with the weakest transport of the upper mid-ocean transport (UMO), from the Bahamas to the eastern boundary, whose amplitude is 4 Sv. The seasonally averaged dynamic height indicates that the major source of seasonal variability in the UMO is due to the eastern boundary in fall. Data from the RAPID/MOCHA array at 26ºN is analyzed together with the data from a 15-year mooring between the African coast and the Canary Islands at 28ºN, in the Lanzarote Passage, the so-called Eastern Boundary Current Mooring (EBC4). The seasonal dynamics of the eastern boundary is analyzed: the recirculation of the Canary Current in fall through the Lanzarote Passage, the Rossby wave formation and the wind forcing. Significant correlations are found between the transport through the LP and the UMO. The transport of the North Atlantic Central Water (NACW) as measured by the EBC4 mooring has a correlation of 0.75 at zero lag with the UMO transport, and the transport of the Antarctic Intermediate Water (AAIW) and Mediterranean Water (MW) are correlated 0.77/0.85 respectively, with a lag of one moth with the UMO. The results stress the importance of the eastern boundary in determining the seasonal variability of the AMOC, as measured by the RAPID/MOCHA array.

Measurements of the ripple effect and geometric distribution of switched gradient fields inside a magnetic resonance scanner.

PubMed

Sundström, Henrik; Mild, Kjell Hansson; Wilén, Jonna

2015-02-01

Knowledge of patient exposure during magnetic resonance imaging (MRI) procedures is limited, and the need for such knowledge has been demonstrated in recent in vitro and in vivo studies of the genotoxic effects of MRI. This study focuses on the dB/dt of the switched gradient field (SGF) and its geometric distribution. These values were characterized by measuring the peak dB/dt generated by a programmed gradient current of alternating triangles inside a 1.5T MR scanner. The maximum dB/dt exposure to the gradient field was 6-14 T/s, and this occurred at the edges of the field of view (FOV) 20-25 cm from the isocenter in the longitudinal direction. The dB/dt exposure dropped off to roughly half the maximum (3-7 T/s) at the edge of the bore. It was found that the dB/dt of the SGF was distorted by a 200 kHz ripple arising from the amplifier. The ripple is small in terms of B-field, but the high frequency content contributes to a peak dB/dt up to 18 times larger than that predicted by the slew rate (4 T/s m) and the distance from the isocenter. Measurements on a 3 T MRI scanner, however, revealed a much smaller filtered ripple of 100 kHz in dB/dt. These findings suggest that the gradient current to each coil together with information on the geometrical distribution of the gradient field and ripple effects could be used to assess the SGF exposure within an MRI bore. © 2014 Wiley Periodicals, Inc.

Ankle and knee kinetics between strike patterns at common training speeds in competitive male runners.

PubMed

Kuhman, Daniel; Melcher, Daniel; Paquette, Max R

2016-01-01

The purpose of this study was to investigate the interaction of foot strike and common speeds on sagittal plane ankle and knee joint kinetics in competitive rear foot strike (RFS) runners when running with a RFS pattern and an imposed forefoot strike (FFS) pattern. Sixteen competitive habitual male RFS runners ran at two different speeds (i.e. 8 and 6 min mile(-1)) using their habitual RFS and an imposed FFS pattern. A repeated measures analysis of variance was used to assess a potential interaction between strike pattern and speed for selected ground reaction force (GRF) variables and, sagittal plane ankle and knee kinematic and kinetic variables. No foot strike and speed interaction was observed for any of the kinetic variables. Habitual RFS yielded a greater loading rate of the vertical GRF, peak ankle dorsiflexor moment, peak knee extensor moment, peak knee eccentric extensor power, peak dorsiflexion and sagittal plane knee range of motion compared to imposed FFS. Imposed FFS yielded greater maximum vertical GRF, peak ankle plantarflexor moment, peak ankle eccentric plantarflexor power and sagittal plane ankle ROM compared to habitual RFS. Consistent with previous literature, imposed FFS in habitual RFS reduces eccentric knee extensor and ankle dorsiflexor involvement but produce greater eccentric ankle plantarflexor action compared to RFS. These acute differences between strike patterns were independent of running speeds equivalent to typical easy and hard training runs in competitive male runners. Current findings along with previous literature suggest differences in lower extremity kinetics between habitual RFS and imposed FFS running are consistent among a variety of runner populations.

Do diurnal patterns of branch carbon uptake and transpiration recover after heat waves? Results from a Mediterranean-type ecosystem experiencing seasonal and exceptional drought

NASA Astrophysics Data System (ADS)

Pivovaroff, A. L.; Pesqueira, A.; Sun, W.; Seibt, U.

2016-12-01

Mediterranean-type ecosystems are biodiversity hotspots, but increasing temperature and changes in precipitation will have significant impacts on vegetation, as evidenced by the current die-back of many woody species in southern California, USA, due to exceptional drought conditions. We installed flow-through chambers on four native woody plant species at Stunt Ranch, a University of California Natural Reserve System site, in order to continuously monitor fluxes of carbon and water at the branch-scale from the growing season through the annual seasonal drought period. Study species included Heteromeles arbutifolia, Malosma laurina, Salvia leucophylla, and Quercus agrifolia. Here we present the results of diurnal flux patterns before, during, and after two extreme heat waves events, when daily maximum temperatures doubled. Under typical summer conditions, which include hot, sunny days, study species exhibited two peaks in carbon assimilation during a diurnal cycle: a peak in the morning and a smaller, secondary peak in the afternoon, separated by a midday depression. During heat wave events, which generally lasted 3 days, species exhibited a small morning peak and no afternoon peak at all. All study species returned to their pre-heat wave diurnal flux patterns, which included the second afternoon peak, when weather conditions returned to normal. Since soil moisture was not affected by the short-term heat wave events, we conclude that the pronounced changes in diurnal patterns, including disappearance of the secondary afternoon peak, are the result of stomatal regulation in response to atmospheric water demand rather than root responses to soil moisture deficits. Our results demonstrate that carbon uptake of native species may be impacted under ongoing climate change when increased temperatures and drought conditions may be sustained.

Implementation and Initial Validation of a 100-Kilowatt Class Nested-Channel Hall Thruster

NASA Technical Reports Server (NTRS)

Hall, Scott J.; Florenz, Roland E.; Gallimore, Alec D.; Kamhawi, Hani; Brown, Daniel L.; Polk, James E.; Goebel, Dan; Hofer, Richard R.

2014-01-01

The X3 is a 100-kilowatt class nested-channel Hall thruster developed by the Plasmadynamics and Electric Propulsion Laboratory at the University of Michigan in collaboration with the Air Force Research Laboratory and NASA. The cathode, magnetic circuit, boron nitride channel rings, and anodes all required specific design considerations during thruster development, and thermal modeling was used to properly account for thermal growth in material selection and component design. A number of facility upgrades were required at the University of Michigan to facilitate operation of the X3. These upgrades included a re-worked propellant feed system, a completely redesigned power and telemetry break-out box, and numerous updates to thruster handling equipment. The X3 was tested on xenon propellant at two current densities, 37% and 73% of the nominal design value. It was operated to a maximum steady-state discharge power of 60.8 kilowatts. The tests presented here served as an initial validation of thruster operation. Thruster behavior was monitored with telemetry, photography and high-speed current probes. The photography showed a uniform plume throughout testing. At constant current density, reductions in mass flow rate of 18% and 26% were observed in the three-channel operating configuration as compared to the superposition of each channel running individually. The high-speed current probes showed that the thruster was stable at all operating points and that the channels influence each other when more than one is operating simultaneously. Additionally, the ratio of peak-to-peak AC-coupled discharge current oscillations to mean discharge current did not exceed 51% for any operating points reported here, and did not exceed 17% at the higher current density.

Comparison of settling particles and sediments at IMAGES coring site in the northwestern North Pacific — Effect of resuspended particles on paleorecords

NASA Astrophysics Data System (ADS)

Kawahata, Hodaka; Minoshima, Kayo; Ishizaki, Yui; Yamaoka, Kyoko; Gupta, Lallan P.; Nagao, Masayuki; Kuroyanagi, Azumi

2009-12-01

In order to understand settling process of particles in high sedimentation area, one mooring of sediment trap was deployed right above the IMAGES coring site in the northwestern North Pacific. In spite of two large maxima of settling particle fluxes in June-July 2002 and October-early January 2003, organic matter (OM) and carbonate showed higher peaks in June-July while lithogenics showed a large peak in October-early January with degraded OM (low aspartic acid/beta-alanine (Asp/Bala) and glutamic acid/gamma-aminobutyric (Glu/Gaba) ratios). Fresh OM production peaked in June-July 2002 and April-May 2003. Thus a large export production occurred in spring-early summer (April-June). Alkenone production was enhanced mainly in June-July. The mean alkenone SST of the settling particles was rather consistent with the observed annual mean SST and alkenone SST determined from the surface sediments. On the other hand, the maximum lithogenic flux along with the degradation of OM indicated that a significant amount of resuspended matter contaminated the bottom sediments. Based upon idealized model, the current and settling speeds make fractionation by size and density of resuspended particles during the settling process. Accumulation rates of lithogenics were ~ 5 times those in the sediment traps, which indicate large contribution of resuspended particles to settling particles especially during October-early January, when the Tsugaru current showed high current speed. These observations call our attention to carefully reconstruct paleo-environments based upon lithogenics and several other proxies such as biogenic silica, which would be biased for example in the record of IMAGES core at Site Shimokita located on the gentle continental slope.

Low-temperature vibrational dynamics of fused silica and binary silicate glasses

NASA Astrophysics Data System (ADS)

Cai, Ling; Shi, Ying; Hrdina, Ken; Moore, Lisa; Wu, Jingshi; Daemen, Luke L.; Cheng, Yongqiang

2018-02-01

Inelastic neutron scattering was used to study the vibrational dynamics of fused silica and its mixed binary glasses that were doped with either TiO2 or K2O . The energy transfer was measured from zero to 180 meV where the so-called Boson peaks (BP) at low energy and molecular vibrations at high energy are included. Although most of the vibrational spectra at the high energy resemble those reported in earlier literature, a defect-mode-like peak is observed for the doped binary systems near 120 meV . At very low temperature, the BP intensity increases rapidly with temperature and then, at higher temperature, the peak intensity decreases. As a result, a maximum is observed in the temperature dependence of the BP intensity. This maximum was shown in all four samples, but the pure SiO2 sample shows the highest intensity peak and the lowest temperature for peak position. Broadband energy spectra reveal a shift of intensity from BP to the more localized modes at higher energy. Temperature evolution of BP and its relationship with heat conduction and thermal expansion are discussed.

Transition from the Unipolar Region to the Sector Zone: Voyager 2, 2013 and 2014

NASA Astrophysics Data System (ADS)

Burlaga, L. F.; Ness, N. F.; Richardson, J. D.

2017-05-01

We discuss magnetic field and plasma observations of the heliosheath made by Voyager 2 (V2) during 2013 and 2014 near solar maximum. A transition from a unipolar region to a sector zone was observed in the azimuthal angle λ between ˜2012.45 and 2013.82. The distribution of λ was strongly singly peaked at 270^\\circ in the unipolar region and double peaked in the sector zone. The δ-distribution was strongly peaked in the unipolar region and very broad in the sector zone. The distribution of daily averages of the magnetic field strength B was Gaussian in the unipolar region and lognormal in the sector zone. The correlation function of B was exponential with an e-folding time of ˜5 days in both regions. The distribution of hourly increments of B was a Tsallis distribution with nonextensivity parameter q = 1.7 ± 0.04 in the unipolar region and q = 1.44 ± 0.12 in the sector zone. The CR-B relationship qualitatively describes the 2013 observations, but not the 2014 observations. A 40 km s-1 increase in the bulk speed associated with an increase in B near 2013.5 might have been produced by the merging of streams. A “D sheet” (a broad depression in B containing a current sheet moved past V2 from days 320 to 345, 2013. The R- and N-components of the plasma velocity changed across the current sheet.

A novel fast phase correlation algorithm for peak wavelength detection of Fiber Bragg Grating sensors.

PubMed

Lamberti, A; Vanlanduit, S; De Pauw, B; Berghmans, F

2014-03-24

Fiber Bragg Gratings (FBGs) can be used as sensors for strain, temperature and pressure measurements. For this purpose, the ability to determine the Bragg peak wavelength with adequate wavelength resolution and accuracy is essential. However, conventional peak detection techniques, such as the maximum detection algorithm, can yield inaccurate and imprecise results, especially when the Signal to Noise Ratio (SNR) and the wavelength resolution are poor. Other techniques, such as the cross-correlation demodulation algorithm are more precise and accurate but require a considerable higher computational effort. To overcome these problems, we developed a novel fast phase correlation (FPC) peak detection algorithm, which computes the wavelength shift in the reflected spectrum of a FBG sensor. This paper analyzes the performance of the FPC algorithm for different values of the SNR and wavelength resolution. Using simulations and experiments, we compared the FPC with the maximum detection and cross-correlation algorithms. The FPC method demonstrated a detection precision and accuracy comparable with those of cross-correlation demodulation and considerably higher than those obtained with the maximum detection technique. Additionally, FPC showed to be about 50 times faster than the cross-correlation. It is therefore a promising tool for future implementation in real-time systems or in embedded hardware intended for FBG sensor interrogation.

A new approach way for white organic light-emitting diodes based on single emitting layer and large stokes shift.

PubMed

Kim, Beomjin; Park, Youngil; Shin, Yunseop; Lee, Jiwon; Shin, Hwangyu; Park, Jongwook

2014-07-01

New red dopant, DPPZ based on porphyrin moiety was synthesized. DPPZ showed UV-Vis and PL maximum values of 412 and 638 nm, indicating the large stokes shift. New blue host compound, TATa was also synthesized and used for co-mixed white emission. TATa exhibited UV-Vis. and PL maximum values of 403 nm and 463 nm in film state. Thus, when two compounds are used as co-mixed emitter in OLED device, there is no energy transfer from blue emission of TATa to DPPZ due to large stokes shift of DPPZ. Based on the PL result, it is available to realize two-colored white in PL and EL spectra. As a result of this, two-mixed compounds showed vivid their own PL emission peaks of 466 and 638 nm in film state. Also, white OLED device using two-mixed compounds system was fabricated. EL spectrum shows 481 and 646 nm peaks and two separate EL peaks. As the operation voltage is increased from 8 to 11 V, EL spectrum does not change the peak shape and maximum wavelength values. EL performance of white device showed 0.041 cd/A, 0.018 Im/W, and CIE (0.457, 0.331) at 8 V.

Selective effects of weight and inertia on maximum lifting.

PubMed

Leontijevic, B; Pazin, N; Kukolj, M; Ugarkovic, D; Jaric, S

2013-03-01

A novel loading method (loading ranged from 20% to 80% of 1RM) was applied to explore the selective effects of externally added simulated weight (exerted by stretched rubber bands pulling downward), weight+inertia (external weights added), and inertia (covariation of the weights and the rubber bands pulling upward) on maximum bench press throws. 14 skilled participants revealed a load associated decrease in peak velocity that was the least associated with an increase in weight (42%) and the most associated with weight+inertia (66%). However, the peak lifting force increased markedly with an increase in both weight (151%) and weight+inertia (160%), but not with inertia (13%). As a consequence, the peak power output increased most with weight (59%), weight+inertia revealed a maximum at intermediate loads (23%), while inertia was associated with a gradual decrease in the peak power output (42%). The obtained findings could be of importance for our understanding of mechanical properties of human muscular system when acting against different types of external resistance. Regarding the possible application in standard athletic training and rehabilitation procedures, the results speak in favor of applying extended elastic bands which provide higher movement velocity and muscle power output than the usually applied weights. © Georg Thieme Verlag KG Stuttgart · New York.

Persistent and energetic bottom-trapped topographic Rossby waves observed in the southern South China Sea.

PubMed

Shu, Yeqiang; Xue, Huijie; Wang, Dongxiao; Chai, Fei; Xie, Qiang; Cai, Shuqun; Chen, Rongyu; Chen, Ju; Li, Jian; He, Yunkai

2016-04-14

Energetic fluctuations with periods of 9-14 days below a depth of 1400 m were observed in the southern South China Sea (SCS) from 5 years of direct measurements. We interpreted such fluctuations as topographic Rossby waves (TRWs) because they obey the dispersion relation. The TRWs persisted from May 24, 2009 to August 23, 2013, and their bottom current speed with a maximum of ~10 cm/s was one order of magnitude greater than the mean current and comparable to the tidal currents near the bottom. The bottom-trapped TRWs had an approximate trapping depth of 325 m and reference wavelength of ~82 km, which were likely excited by eddies above. Upper layer current speed that peaked approximately every 2 months could offer the energy sources for the persistent TRWs in the southern SCS. Energetic bottom-trapped TRWs may have a comparable role in deep circulation to tides in areas with complex topography.

Persistent and energetic bottom-trapped topographic Rossby waves observed in the southern South China Sea

PubMed Central

Shu, Yeqiang; Xue, Huijie; Wang, Dongxiao; Chai, Fei; Xie, Qiang; Cai, Shuqun; Chen, Rongyu; Chen, Ju; Li, Jian; He, Yunkai

2016-01-01

Energetic fluctuations with periods of 9–14 days below a depth of 1400 m were observed in the southern South China Sea (SCS) from 5 years of direct measurements. We interpreted such fluctuations as topographic Rossby waves (TRWs) because they obey the dispersion relation. The TRWs persisted from May 24, 2009 to August 23, 2013, and their bottom current speed with a maximum of ~10 cm/s was one order of magnitude greater than the mean current and comparable to the tidal currents near the bottom. The bottom-trapped TRWs had an approximate trapping depth of 325 m and reference wavelength of ~82 km, which were likely excited by eddies above. Upper layer current speed that peaked approximately every 2 months could offer the energy sources for the persistent TRWs in the southern SCS. Energetic bottom-trapped TRWs may have a comparable role in deep circulation to tides in areas with complex topography. PMID:27075644

Influence of sleep and meal schedules on performance peaks in competitive sprinters.

PubMed

Javierre, C; Calvo, M; Díez, A; Garrido, E; Segura, R; Ventura, J L

1996-08-01

The influence of sleep and meal schedules on performance in short distance running was assessed in a group of 8 national-class competition male sprinters. They were tested on Saturdays for five consecutive weeks. On each testing day, the performance time for an 80 m sprint was registered on eight different occasions during days 1 and 4, on 9 occasions on days 2 and 5, and on 7 occasions on day 3. On control days (days 1 and 4) performance gradually improved during the morning up to 13:00 h, decreased at 15:00 h, and again improved thereafter, with a maximum peak performance at 19:00 h. On day 2, in which sleep/wake cycles and meal-times were advanced for two hours, and on day 3, in which timetables were delayed for two hours, maximum peak performance was observed at 17:00 h and 21:00 h, respectively. At the time of maximum peak performance on both days a statistically significant improvement was observed as compared with the control day (day 2, p < 0.01; day 3, p = 0.001). On day 5, in which only the sleep/wake cycle was advanced for two hours, performance in the afternoon and evening was similar to that recorded on days 1 and 4. We observed that easy manipulation of sleep and meal schedules would allow competitive sprinters to synchronize peak power output with the time of the athletic event, increasing the chances for improvement in performance.

The associations between quadriceps muscle strength, power, and knee joint mechanics in knee osteoarthritis: A cross-sectional study.

PubMed

Murray, Amanda M; Thomas, Abbey C; Armstrong, Charles W; Pietrosimone, Brian G; Tevald, Michael A

2015-12-01

Abnormal knee joint mechanics have been implicated in the pathogenesis and progression of knee osteoarthritis. Deficits in muscle function (i.e., strength and power) may contribute to abnormal knee joint loading. The associations between quadriceps strength, power and knee joint mechanics remain unclear in knee osteoarthritis. Three-dimensional motion analysis was used to collect peak knee joint angles and moments during the first 50% of stance phase of gait in 33 participants with knee osteoarthritis. Quadriceps strength and power were assessed using a knee extension machine. Strength was quantified as the one repetition maximum. Power was quantified as the peak power produced at 40-90% of the one repetition maximum. Quadriceps strength accounted for 15% of the variance in peak knee flexion angle (P=0.016). Quadriceps power accounted for 20-29% of the variance in peak knee flexion angle (P<0.05). Quadriceps power at 90% of one repetition maximum accounted for 9% of the variance in peak knee adduction moment (P=0.05). These data suggest that quadriceps power explains more variance in knee flexion angle and knee adduction moment during gait in knee osteoarthritis than quadriceps strength. Additionally, quadriceps power at multiple loads is associated with knee joint mechanics and therefore should be assessed at a variety of loads. Taken together, these results indicate that quadriceps power may be a potential target for interventions aimed at changing knee joint mechanics in knee osteoarthritis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characterization of a High Current, Long Life Hollow Cathode

NASA Technical Reports Server (NTRS)

VanNoord, Jonathan L.; Kamhawi, Hani; McEwen, Heather K.

2006-01-01

The advent of higher power spacecraft makes it desirable to use higher power electric propulsion thrusters such as ion thrusters or Hall thrusters. Higher power thrusters require cathodes that are capable of producing higher currents. One application of these higher power spacecraft is deep-space missions that require tens of thousands of hours of operation. This paper presents the approach used to design a high current, long life hollow cathode assembly for that application, along with test results from the corresponding hollow cathode. The design approach used for the candidate hollow cathode was to reduce the temperature gradient in the insert, yielding a lower peak temperature and allowing current to be produced more uniformly along the insert. The lower temperatures result in a hollow cathode with increased life. The hollow cathode designed was successfully operated at currents from 10 to 60 A with flow rates of 5 to 19 sccm with a maximum orifice temperature measured of 1100 C. Data including discharge voltage, keeper voltage, discharge current, flow rates, and orifice plate temperatures are presented.

In Vivo Voltage-Sensitive Dye Study of Lateral Spreading of Cortical Activity in Mouse Primary Visual Cortex Induced by a Current Impulse

PubMed Central

Fehérvári, Tamás Dávid; Sawai, Hajime; Yagi, Tetsuya

2015-01-01

In the mammalian primary visual cortex (V1), lateral spreading of excitatory potentials is believed to be involved in spatial integrative functions, but the underlying cortical mechanism is not well understood. Visually-evoked population-level responses have been shown to propagate beyond the V1 initial activation site in mouse, similar to higher mammals. Visually-evoked responses are, however, affected by neuronal circuits prior to V1 (retina, LGN), making the separate analysis of V1 difficult. Intracortical stimulation eliminates these initial processing steps. We used in vivo RH1691 voltage-sensitive dye (VSD) imaging and intracortical microstimulation in adult C57BL/6 mice to elucidate the spatiotemporal properties of population-level signal spreading in V1 cortical circuits. The evoked response was qualitatively similar to that measured in single-cell electrophysiological experiments in rodents: a fast transient fluorescence peak followed by a fast and a slow decrease or hyperpolarization, similar to EPSP and fast and slow IPSPs in single cells. The early cortical response expanded at speeds commensurate with long horizontal projections (at 5% of the peak maximum, 0.08–0.15 m/s) however, the bulk of the VSD signal propagated slowly (at half-peak maximum, 0.05–0.08 m/s) suggesting an important role of regenerative multisynaptic transmission through short horizontal connections in V1 spatial integrative functions. We also found a tendency for a widespread and fast cortical response suppression in V1, which was eliminated by GABAA-antagonists gabazine and bicuculline methiodide. Our results help understand the neuronal circuitry involved in lateral spreading in V1. PMID:26230520

Faster Movement Speed Results in Greater Tendon Strain during the Loaded Squat Exercise

PubMed Central

Earp, Jacob E.; Newton, Robert U.; Cormie, Prue; Blazevich, Anthony J.

2016-01-01

Introduction: Tendon dynamics influence movement performance and provide the stimulus for long-term tendon adaptation. As tendon strain increases with load magnitude and decreases with loading rate, changes in movement speed during exercise should influence tendon strain. Methods: Ten resistance-trained men [squat one repetition maximum (1RM) to body mass ratio: 1.65 ± 0.12] performed parallel-depth back squat lifts with 60% of 1RM load at three different speeds: slow fixed-tempo (TS: 2-s eccentric, 1-s pause, 2-s concentric), volitional-speed without a pause (VS) and maximum-speed jump (JS). In each condition joint kinetics, quadriceps tendon length (LT), patellar tendon force (FT), and rate of force development (RFDT) were estimated using integrated ultrasonography, motion-capture, and force platform recordings. Results: Peak LT, FT, and RFDT were greater in JS than TS (p < 0.05), however no differences were observed between VS and TS. Thus, moving at faster speeds resulted in both greater tendon stress and strain despite an increased RFDT, as would be predicted of an elastic, but not a viscous, structure. Temporal comparisons showed that LT was greater in TS than JS during the early eccentric phase (10–14% movement duration) where peak RFDT occurred, demonstrating that the tendon's viscous properties predominated during initial eccentric loading. However, during the concentric phase (61–70 and 76–83% movement duration) differing FT and similar RFDT between conditions allowed for the tendon's elastic properties to predominate such that peak tendon strain was greater in JS than TS. Conclusions: Based on our current understanding, there may be an additional mechanical stimulus for tendon adaptation when performing large range-of-motion isoinertial exercises at faster movement speeds. PMID:27630574

ScienceCast 94: Solar Max Double Peaked

NASA Image and Video Library

2013-03-01

Something unexpected is happening on the sun. 2013 is supposed to be the year of Solar Max, but solar activity is much lower than expected. At least one leading forecaster expects the sun to rebound with a double-peaked maximum later this year.

Validation of an "Intelligent Mouthguard" Single Event Head Impact Dosimeter.

PubMed

Bartsch, Adam; Samorezov, Sergey; Benzel, Edward; Miele, Vincent; Brett, Daniel

2014-11-01

Dating to Colonel John Paul Stapp MD in 1975, scientists have desired to measure live human head impacts with accuracy and precision. But no instrument exists to accurately and precisely quantify single head impact events. Our goal is to develop a practical single event head impact dosimeter known as "Intelligent Mouthguard" and quantify its performance on the benchtop, in vitro and in vivo. In the Intelligent Mouthguard hardware, limited gyroscope bandwidth requires an algorithm-based correction as a function of impact duration. After we apply gyroscope correction algorithm, Intelligent Mouthguard results at time of CG linear acceleration peak correlate to the Reference Hybrid III within our tested range of pulse durations and impact acceleration profiles in American football and Boxing in vitro tests: American football, IMG=1.00REF-1.1g, R2=0.99; maximum time of peak XYZ component imprecision 3.6g and 370 rad/s2; maximum time of peak azimuth and elevation imprecision 4.8° and 2.9°; maximum average XYZ component temporal imprecision 3.3g and 390 rad/s2. Boxing, IMG=1.00REF-0.9 g, R2=0.99, R2=0.98; maximum time of peak XYZ component imprecision 3.9 g and 390 rad/s2, maximum time of peak azimuth and elevation imprecision 2.9° and 2.1°; average XYZ component temporal imprecision 4.0 g and 440 rad/s2. In vivo Intelligent Mouthguard true positive head impacts from American football players and amateur boxers have temporal characteristics (first harmonic frequency from 35 Hz to 79 Hz) within our tested benchtop (first harmonic frequency<180 Hz) and in vitro (first harmonic frequency<100 Hz) ranges. Our conclusions apply only to situations where the rigid body assumption is valid, sensor-skull coupling is maintained and the ranges of tested parameters and harmonics fall within the boundaries of harmonics validated in vitro. For these situations, Intelligent Mouthguard qualifies as a single event dosimeter in American football and Boxing.

Analysis of trends in selected streamflow statistics for the Concho River Basin, Texas, 1916-2009

USGS Publications Warehouse

Barbie, Dana L.; Wehmeyer, Loren L.; May, Jayne E.

2012-01-01

Six U.S. Geological Survey streamflow-gaging stations were selected for analysis. Streamflow-gaging station 08128000 South Concho River at Christoval has downward trends for annual maximum daily discharge and annual instantaneous peak discharge for the combined period 1931-95, 2002-9. Streamflow-gaging station 08128400 Middle Concho River above Tankersley has downward trends for annual maximum daily discharge and annual instantaneous peak discharge for the combined period 1962-95, 2002-9. Streamflow-gaging station 08128500 Middle Concho River near Tankersley has no significant trends in the streamflow statistics considered for the period 1931-60. Streamflow-gaging station 08134000 North Concho River near Carlsbad has downward trends for annual mean daily discharge, annual 7-day minimum daily discharge, annual maximum daily discharge, and annual instantaneous peak discharge for the period 1925-2009. Streamflow-gaging stations 08136000 Concho River at San Angelo and 08136500 Concho River at Paint Rock have downward trends for 1916-2009 for all streamflow statistics calculated, but streamflow-gaging station 08136000 Concho River at San Angelo has an upward trend for annual maximum daily discharge during 1964-2009. The downward trends detected during 1916-2009 for the Concho River at San Angelo are not unexpected because of three reservoirs impounding and profoundly regulating streamflow.

Efficient 1.5-μm Raman generation in ethane-filled hollow-core fiber

NASA Astrophysics Data System (ADS)

Chen, Yubin; Gu, Bo; Wang, Zefeng; Lu, Qisheng

2016-11-01

We demonstrated for the first time a novel and effective method for obtaining both high peak-power and narrow linewidth 1.5 μm fiber sources through gas Raman effect in hollow core fibers. An Ethane-filled ice-cream antiresonance hollow-core fiber is pumped with a high peak-power pulse 1064 nm microchip laser, generating 1552.7 nm Stokes wave by pure vibrational stimulated Raman scattering of ethane molecules. A maximum peak-power of about 400 kW is achieved with 6 meter fiber length at 2 bar pressure, and the linewidth is about 6.3 GHz. The maximum Raman conversion efficiency of 1064 nm to 1552.7 nm is about 38%, and the corresponding laser slope efficiency is about 61.5%.

Characterization of 3-Dimensional PET Systems for Accurate Quantification of Myocardial Blood Flow.

PubMed

Renaud, Jennifer M; Yip, Kathy; Guimond, Jean; Trottier, Mikaël; Pibarot, Philippe; Turcotte, Eric; Maguire, Conor; Lalonde, Lucille; Gulenchyn, Karen; Farncombe, Troy; Wisenberg, Gerald; Moody, Jonathan; Lee, Benjamin; Port, Steven C; Turkington, Timothy G; Beanlands, Rob S; deKemp, Robert A

2017-01-01

Three-dimensional (3D) mode imaging is the current standard for PET/CT systems. Dynamic imaging for quantification of myocardial blood flow with short-lived tracers, such as 82 Rb-chloride, requires accuracy to be maintained over a wide range of isotope activities and scanner counting rates. We proposed new performance standard measurements to characterize the dynamic range of PET systems for accurate quantitative imaging. 82 Rb or 13 N-ammonia (1,100-3,000 MBq) was injected into the heart wall insert of an anthropomorphic torso phantom. A decaying isotope scan was obtained over 5 half-lives on 9 different 3D PET/CT systems and 1 3D/2-dimensional PET-only system. Dynamic images (28 × 15 s) were reconstructed using iterative algorithms with all corrections enabled. Dynamic range was defined as the maximum activity in the myocardial wall with less than 10% bias, from which corresponding dead-time, counting rates, and/or injected activity limits were established for each scanner. Scatter correction residual bias was estimated as the maximum cavity blood-to-myocardium activity ratio. Image quality was assessed via the coefficient of variation measuring nonuniformity of the left ventricular myocardium activity distribution. Maximum recommended injected activity/body weight, peak dead-time correction factor, counting rates, and residual scatter bias for accurate cardiac myocardial blood flow imaging were 3-14 MBq/kg, 1.5-4.0, 22-64 Mcps singles and 4-14 Mcps prompt coincidence counting rates, and 2%-10% on the investigated scanners. Nonuniformity of the myocardial activity distribution varied from 3% to 16%. Accurate dynamic imaging is possible on the 10 3D PET systems if the maximum injected MBq/kg values are respected to limit peak dead-time losses during the bolus first-pass transit. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Time-resolved imaging of the plasma development in a triggered vacuum switch

NASA Astrophysics Data System (ADS)

Park, Wung-Hoa; Kim, Moo-Sang; Son, Yoon-Kyoo; Frank, Klaus; Lee, Byung-Joon; Ackerman, Thilo; Iberler, Marcus

2017-12-01

Triggered vacuum switches (TVS) are particularly used in pulsed power technology as closing switches for high voltages and high charge transfer. A non-sealed-off prototype was designed with a side-on quartz window to investigate the evolution of the trigger discharge into the main discharge. The image acquisition was done with a fast CCD camera PI-MAX2 from Princeton Instruments. The CCD camera has a maximum exposure time of 2 ns. The electrode configuration of the prototype is a conventional six-rod gap type, a capacitor bank with C = 16.63 μF, which corresponds at 20 kV charging voltage to a total stored charge of 0.3 C or a total energy of 3.3 kJ. The peak current is 88 kA. According to the tremendously highly different light intensities during the trigger and main discharge, the complete discharge is split into three phases: a trigger breakdown phase, an intermediate phase and a main discharge phase. The CCD camera images of the first phase show instabilities of the trigger breakdown, in phase 2 three different discharge modes are observed. After the first current maximum the discharge behavior is reproducible.

Variations in Solar Parameters and Cosmic Rays with Solar Magnetic Polarity

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

Oh, S.; Yi, Y., E-mail: suyeonoh@jnu.ac.kr

The sunspot number varies with the 11-year Schwabe cycle, and the solar magnetic polarity reverses every 11 years approximately at the solar maximum. Because of polarity reversal, the difference between odd and even solar cycles is seen in solar activity. In this study, we create the mean solar cycle expressed by phase using the monthly sunspot number for all solar cycles 1–23. We also generate the mean solar cycle for sunspot area, solar radio flux, and cosmic ray flux within the allowance of observational range. The mean solar cycle has one large peak at solar maximum for odd solar cyclesmore » and two small peaks for most even solar cycles. The odd and even solar cycles have the statistical difference in value and shape at a confidence level of at least 98%. For solar cycles 19–23, the second peak in the even solar cycle is larger than the first peak. This result is consistent with the frequent solar events during the declining phase after the solar maximum. The difference between odd and even solar cycles can be explained by a combined model of polarity reversal and solar rotation. In the positive/negative polarity, the polar magnetic field introduces angular momentum in the same/opposite direction as/to the solar rotation. Thus the addition/subtraction of angular momentum can increase/decrease the motion of plasma to support the formation of sunspots. Since the polarity reverses at the solar maximum, the opposite phenomenon occurs in the declining phase.« less

The effects of age and step length on joint kinematics and kinetics of large out-and-back steps.

PubMed

Schulz, Brian W; Ashton-Miller, James A; Alexander, Neil B

2008-06-01

Maximum step length (MSL) is a clinical test that has been shown to correlate with age, various measures of fall risk, and knee and hip joint extension speed, strength, and power capacities, but little is known about the kinematics and kinetics of the large out-and-back step utilized. Body motions and ground reaction forces were recorded for 11 unimpaired younger and 10 older women while attaining maximum step length. Joint kinematics and kinetics were calculated using inverse dynamics. The effects of age group and step length on the biomechanics of these large out-and-back steps were determined. Maximum step length was 40% greater in the younger than in the older women (P<0.0001). Peak knee and hip, but not ankle, angle, velocity, moment, and power were generally greater for younger women and longer steps. After controlling for age group, step length generally explained significant additional variance in hip and torso kinematics and kinetics (incremental R2=0.09-0.37). The young reached their peak knee extension moment immediately after landing of the step out, while the old reached their peak knee extension moment just before the return step liftoff (P=0.03). Maximum step length is strongly associated with hip kinematics and kinetics. Delays in peak knee extension moment that appear to be unrelated to step length, may indicate a reduced ability of older women to rapidly apply force to the ground with the stepping leg and thus arrest the momentum of a fall.

The effects of age and step length on joint kinematics and kinetics of large out-and-back steps

PubMed Central

Schulz, Brian W.; Ashton-Miller, James A.; Alexander, Neil B.

2008-01-01

Background Maximum Step Length is a clinical test that has been shown to correlate with age, various measures of fall risk, and knee and hip joint extension speed, strength, and power capacities, but little is known about the kinematics and kinetics of the large out-and-back step utilized. Methods Body motions and ground reaction forces were recorded for 11 unimpaired younger and 10 older women while attaining Maximum Step Length. Joint kinematics and kinetics were calculated using inverse dynamics. The effects of age group and step length on the biomechanics of these large out-and-back steps were determined. Findings Maximum Step Length was 40% greater in the younger than in the older women (p<0.0001). Peak knee and hip, but not ankle, angle, velocity, moment, and power were generally greater for younger women and longer steps. After controlling for age group, step length generally explained significant additional variance in hip and torso kinematics and kinetics (incremental R2=0.09–0.37). The young reached their peak knee extension moment immediately after landing of the step out, while the old reached their peak knee extension moment just before the return step lift off (p=0.03). Interpretation Maximum Step Length is strongly associated with hip kinematics and kinetics. Delays in peak knee extension moment that appear to be unrelated to step length, may indicate a reduced ability of older women to rapidly apply force to the ground with the stepping leg and thus arrest the momentum of a fall. PMID:18308435

Ice Action on Pairs of Cylindrical and Conical Structures,

DTIC Science & Technology

1983-09-01

correlation because the forces generated ficult to pick a distinct peak in the autospectra for between the structure and the ice sheet are af- the...against two conical structures ...... 20 24. Normalized maximum ice force versus ice velocity ................. 20 25. Normalized initial peak force...versus ice velocity .................. 21 26. Ratio of initial peak ice force to theoretical ice force versus ratio of center-to-center distance

Power and impulse applied during push press exercise.

PubMed

Lake, Jason P; Mundy, Peter D; Comfort, Paul

2014-09-01

The aim of this study was to quantify the load, which maximized peak and mean power, and impulse applied to these loads, during the push press and to compare them to equivalent jump squat data. Resistance-trained men performed 2 push press (n = 17; age: 25.4 ± 7.4 years; height: 183.4 ± 5 cm; body mass: 87 ± 15.6 kg) and jump squat (n = 8 of original 17; age: 28.7 ± 8.1 years; height: 184.3 ± 5.5 cm; mass: 98 ± 5.3 kg) singles with 10-90% of their push press and back squat 1 repetition maximum (1RM), respectively, in 10% 1RM increments while standing on a force platform. Push press peak and mean power was maximized with 75.3 ± 16.4 and 64.7 ± 20% 1RM, respectively, and impulses applied to these loads were 243 ± 29 N·s and 231 ± 36 N·s. Increasing and decreasing load, from the load that maximized peak and mean power, by 10 and 20% 1RM reduced peak and mean power by 6-15% (p ≤ 0.05). Push press and jump squat maximum peak power (7%, p = 0.08) and the impulse that was applied to the load that maximized peak (8%, p = 0.17) and mean (13%, p = 0.91) power were not significantly different, but push press maximum mean power was significantly greater than the jump squat equivalent (∼9.5%, p = 0.03). The mechanical demand of the push press is comparable with the jump squat and could provide a time-efficient combination of lower-body power and upper-body and trunk strength training.

Determinant Factors of the Squat Jump in Sprinting and Jumping Athletes

PubMed Central

González-Badillo, Juan José; Jiménez-Reyes, Pedro; Ramírez-Lechuga, Jorge

2017-01-01

Abstract The aim of this study was to assess the relationship between strength variables and maximum velocity (Vmax) in the squat jump (SJ) in sprinting and jumping athletes. Thirty-two sprinting and jumping athletes of national level (25.4 ± 4.5 years; 79.4 ± 6.9 kg and 180.4 ± 6.0 cm) participated in the study. Vmax in the SJ showed significant relationships with peak force 1 (PF1) (r = 0.82, p ≤ 0.001), peak force 2 (PF2) (r = 0.68, p ≤ 0.001), PF2 by controlling for PF1 (r = 0.30, non-significant), the maximum rate of force development at peak force 1 (RFDmax1) (r = 0.62, p ≤ 0.001), mean RFD 1 (RFDmean1) (r = 0.48, p ≤ 0.01), mean RFD 2 (RFDmean2) (r = 0.70, p ≤ 0.001), force at RFDmax1 (r = 0.36, p ≤ 0.05), force at RFDmax2 (r = 0.83, p ≤ 0.001) and force at RFDmax2 by controlling for PF1 (r = 0.40, p ≤ 0.05). However, Vmax in the SJ was associated negatively with the ratio PF2/PF1 (r = -0.54, p ≤ 0.01), time at peak force 2 (Tp2) (r = -0.64, p ≤ 0.001) and maximum rate of force development at peak force 2 (RFDmax2) (r = -0.71, p ≤ 0.001). These findings indicate that the peak force achieved at the beginning of the movement (PF1) is the main predictor of performance in jumping, although the RFDmax values and the ratio PF2/PF1 are also variables to be taken into account when analyzing the determinant factors of vertical jumping. PMID:28828074

Tunneling measurement of quantum spin oscillations

NASA Astrophysics Data System (ADS)

Bulaevskii, L. N.; Hruška, M.; Ortiz, G.

2003-09-01

We consider the problem of tunneling between two leads via a localized spin 1/2 or any other microscopic system (e.g., a quantum dot) which can be modeled by a two-level Hamiltonian. We assume that a constant magnetic field B0 acts on the spin, that electrons in the leads are in a voltage driven thermal equilibrium, and that the tunneling electrons are coupled to the spin through exchange and spin-orbit interactions. Using the nonequilibrium Keldysh formalism we find the dependence of the spin-spin and current-current correlation functions on the applied voltage between leads V, temperature T, B0, and on the degree and orientation mα of spin polarization of the electrons in the right (α=R) and left (α=L) leads. We show the following (a) The spin-spin correlation function exhibits a peak at the Larmor frequency, ωL, corresponding to the effective magnetic field B acting upon the spin as determined by B0 and the exchange field induced by tunneling of spin-polarized electrons. (b) If the mα’s are not parallel to B the second-order derivative of the average tunneling current I(V) with respect to V is proportional to the spectral density of the spin-spin correlation function, i.e., exhibits a peak at the voltage V=ħωL/e. (c) In the same situation when V>B the current-current correlation function exhibits a peak at the same frequency. (d) The signal-to-noise (shot-noise) ratio R for this peak reaches a maximum value of order unity, R⩽4, at large V when the spin is decoupled from the environment and the electrons in both leads are fully polarized in the direction perpendicular to B. (e) R≪1 if the electrons are weakly polarized, or if they are polarized in a direction close to B0, or if the spin interacts with the environment stronger than with the tunneling electrons. Our results of a full quantum-mechanical treatment of the tunneling-via-spin model when V≫B are in agreement with those previously obtained in the quasiclassical approach. We discuss also the experimental results observed using scanning tunneling microscopy dynamic probes of the localized spin.

Methodology and implications of maximum paleodischarge estimates for mountain channels, upper Animas River basin, Colorado, U.S.A.

USGS Publications Warehouse

Pruess, J.; Wohl, E.E.; Jarrett, R.D.

1998-01-01

Historical and geologic records may be used to enhance magnitude estimates for extreme floods along mountain channels, as demonstrated in this study from the San Juan Mountains of Colorado. Historical photographs and local newspaper accounts from the October 1911 flood indicate the likely extent of flooding and damage. A checklist designed to organize and numerically score evidence of flooding was used in 15 field reconnaissance surveys in the upper Animas River valley of southwestern Colorado. Step-backwater flow modeling estimated the discharges necessary to create longitudinal flood bars observed at 6 additional field sites. According to these analyses, maximum unit discharge peaks at approximately 1.3 m3 s-1 km-2 around 2200 m elevation, with decreased unit discharges at both higher and lower elevations. These results (1) are consistent with Jarrett's (1987, 1990, 1993) maximum 2300-m elevation limit for flash-flooding in the Colorado Rocky Mountains, and (2) suggest that current Probable Maximum Flood (PMF) estimates based on a 24-h rainfall of 30 cm at elevations above 2700 m are unrealistically large. The methodology used for this study should be readily applicable to other mountain regions where systematic streamflow records are of short duration or nonexistent.

Floods of August and September 1971 in Maryland and Delaware

USGS Publications Warehouse

Carpenter, D.H.

1974-01-01

Flood discharge data are presented for 75 gaging stations and for 6 miscellaneous sites. New peaks of record occurred at 32 of the gaging stations. The maximum unit peak discharge rate recorded was 2,400 cubic fee t per second per square mile.

Rheoencephalographic (REG) Assessment of Head and Neck Cooling for use with Multiple Sclerosis Patients

NASA Technical Reports Server (NTRS)

Montogomery, Leslie D.; Ku, Yu-Tsuan E.; Webbon, Bruce W. (Technical Monitor)

1995-01-01

We have prepared a computer program (RHEOSYS:RHEOencephalographic impedance trace scanning SyStem) that can be used to automate the analysis of segmental impedance blood flow waveforms. This program was developed to assist in the post test analysis of recorded impedance traces from multiple segments of the body. It incorporates many of the blood flow, segmental volume, and vascular state indices reported in the world literature. As it is currently programmed, seven points are selected from each blood flow pulse and associated ECG waveforrn: 1. peak of the first ECG QRS complex, 2. start of systolic slope on the blood flow trace, 3. maximum amplitude of the impedance pulse, 4. position of the dicrotic notch, 5. maximum amplitude of the postdicrotic segment, 6. peak of the second ECG QRS complex, and 7. start of the next blood flow pulse. These points we used to calculate various geometric, area, and time-related values associated with the impedance pulse morphology. RHEOSYS then calculates a series of 34 impedance and cardiac cycle parameters which include pulse amplitudes; areas; pulse propagation times; cardiac cycle times; and various measures of arterial and various tone, contractility, and pulse volume. We used this program to calculate the scalp and intracranial blood flow responses to head and neck cooling as it may be applied to lower the body temperatures of multiple sclerosis patients. Twelve women and twelve men were tested using a commercially available head and neck cooling system operated at its maximum cooling capacity for a period of 30 minutes. Head and neck cooling produced a transient change in scalp blood flow and a significant, (P<0.05) decrease of approx. 30% in intracranial blood flow. Results of this experiment will illustrate how REG and RHEOSYS can be used in biomedical applications.

Two classes of fast-declining Type Ia supernovae

NASA Astrophysics Data System (ADS)

Dhawan, Suhail; Leibundgut, B.; Spyromilio, J.; Blondin, S.

2017-06-01

We aim to characterise a sample of fast-declining Type Ia supernovae (SN Ia) using their bolometric and near-infrared (NIR) properties. Based on these properties, we find that fast-declining SN Ia separate into two categories based on their bolometric and NIR properties. The peak bolometric luminosity (Lmax), the phase of the first maximum relative to the optical, the NIR peak luminosity, and the occurrence of a second maximum in the NIR distinguish a group of very faint SN Ia. Fast-declining supernovae show a large range of peak bolometric luminosities (Lmax differing by up to a factor of 8). All fast-declining SN Ia with Lmax < 0.3× 1043 erg s-1 are spectroscopically classified as 91bg-like and show only a single NIR peak. SNe with Lmax > 0.5× 1043 erg s-1 appear to smoothly connect to normal SN Ia. The total ejecta mass (Mej) values for SNe with enough late time data are ≲1 M⊙, indicating a sub-Chandrasekhar mass progenitor for these SNe.

Variations of Scale Height at F-Region Peak Based on Ionosonde Measurements during Solar Maximum over the Crest of Equatorial Ionization Anomaly Region

PubMed Central

Chuo, Yu-Jung

2014-01-01

Scale height is an important parameter in characterizing the shape of the ionosphere and its physical processes. In this study, we attempt to examine and discuss the variation of scale height, H m, around the F-layer peak height during high solar activity at the northern crest of the equatorial ionization anomaly (EIA) region. H m exhibits day-to-day variation and seasonal variation, with a greater average daily variation during daytime in summer. Furthermore, the diurnal variation of H m exhibits an abnormal peak at presunrise during all the seasons, particularly in winter. This increase is also observed in the F2-layer peak height for the same duration with an upward movement associated with thermospheric wind toward the equator; this upward movement increases the N2/O ratio and H m, but it causes a decrease in the F2-layer maximum critical frequency during the presunrise period. PMID:25162048

Different types of maximum power point tracking techniques for renewable energy systems: A survey

NASA Astrophysics Data System (ADS)

Khan, Mohammad Junaid; Shukla, Praveen; Mustafa, Rashid; Chatterji, S.; Mathew, Lini

2016-03-01

Global demand for electricity is increasing while production of energy from fossil fuels is declining and therefore the obvious choice of the clean energy source that is abundant and could provide security for development future is energy from the sun. In this paper, the characteristic of the supply voltage of the photovoltaic generator is nonlinear and exhibits multiple peaks, including many local peaks and a global peak in non-uniform irradiance. To keep global peak, MPPT is the important component of photovoltaic systems. Although many review articles discussed conventional techniques such as P & O, incremental conductance, the correlation ripple control and very few attempts have been made with intelligent MPPT techniques. This document also discusses different algorithms based on fuzzy logic, Ant Colony Optimization, Genetic Algorithm, artificial neural networks, Particle Swarm Optimization Algorithm Firefly, Extremum seeking control method and hybrid methods applied to the monitoring of maximum value of power at point in systems of photovoltaic under changing conditions of irradiance.

Thermal emission from large area chemical vapor deposited graphene devices

NASA Astrophysics Data System (ADS)

Luxmoore, I. J.; Adlem, C.; Poole, T.; Lawton, L. M.; Mahlmeister, N. H.; Nash, G. R.

2013-09-01

The spatial variation of thermal emission from large area graphene grown by chemical vapor deposition, transferred onto SiO2/Si substrates and fabricated into field effect transistor structures, has been investigated using infra-red microscopy. A peak in thermal emission occurs, the position of which can be altered by reversal of the current direction. The experimental results are compared with a one dimensional finite element model, which accounts for Joule heating and electrostatic effects, and it is found that the thermal emission is governed by the charge distribution in the graphene and maximum Joule heating occurs at the point of minimum charge density.

Returners Exhibit Greater Jumping Performance Improvements During a Peaking Phase Compared With New Players on a Volleyball Team.

PubMed

Bazyler, Caleb D; Mizuguchi, Satoshi; Kavanaugh, Ashley A; McMahon, John J; Comfort, Paul; Stone, Michael H

2018-06-21

To determine if jumping-performance changes during a peaking phase differed among returners and new players on a female collegiate volleyball team and to determine which variables best explained the variation in performance changes. Fourteen volleyball players were divided into 2 groups-returners (n = 7) and new players (n = 7)-who completed a 5-wk peaking phase prior to conference championships. Players were tested at baseline before the preseason on measures of the vastus lateralis cross-sectional area using ultrasonography, estimated back-squat 1-repetition maximum, countermovement jump height (JH), and relative peak power on a force platform. Jumping performance, rating of perceived exertion training load, and sets played were recorded weekly during the peaking phase. There were moderate to very large (P < .01, Glass Δ = 1.74) and trivial to very large (P = .07, Δ = 1.09) differences in JH and relative peak power changes in favor of returners over new players, respectively, during the peaking phase. Irrespective of group, 7 of 14 players achieved peak JH 2 wk after the initial overreach. The number of sets played (r = .78, P < .01) and the athlete's preseason relative 1-repetition maximum (r = .54, P = .05) were the strongest correlates of JH changes during the peaking phase. Returners achieved greater improvements in jumping performance during the peaking phase compared with new players, which may be explained by the returners' greater relative maximal strength, time spent competing, and training experience. Thus, volleyball and strength coaches should consider these factors when prescribing training during a peaking phase to ensure their players are prepared for important competitions.

Role of peak current in conversion of patients with ventricular fibrillation.

PubMed

Anantharaman, Venkataraman; Wan, Paul Weng; Tay, Seow Yian; Manning, Peter George; Lim, Swee Han; Chua, Siang Jin Terrance; Mohan, Tiru; Rabind, Antony Charles; Vidya, Sudarshan; Hao, Ying

2017-07-01

Peak currents are the final arbiter of defibrillation in patients with ventricular fibrillation (VF). However, biphasic defibrillators continue to use energy in joules for electrical conversion in hopes that their impedance compensation properties will address transthoracic impedance (TTI), which must be overcome when a fixed amount of energy is delivered. However, optimal peak currents for conversion of VF remain unclear. We aimed to determine the role of peak current and optimal peak levels for conversion in collapsed VF patients. Adult, non-pregnant patients presenting with non-traumatic VF were included in the study. All defibrillations that occurred were included. Impedance values during defibrillation were used to calculate peak current values. The endpoint was return of spontaneous circulation (ROSC). Of the 197 patients analysed, 105 had ROSC. Characteristics of patients with and without ROSC were comparable. Short duration of collapse < 10 minutes correlated positively with ROSC. Generally, patients with average or high TTI converted at lower peak currents. 25% of patients with high TTI converted at 13.3 ± 2.3 A, 22.7% with average TTI at 18.2 ± 2.5 A and 18.6% with low TTI at 27.0 ± 4.7 A (p = 0.729). Highest peak current conversions were at < 15 A and 15-20 A. Of the 44 patients who achieved first-shock ROSC, 33 (75.0%) received < 20 A peak current vs. > 20 A for the remaining 11 (25%) patients (p = 0.002). For best effect, priming biphasic defibrillators to deliver specific peak currents should be considered. Copyright: © Singapore Medical Association

Role of peak current in conversion of patients with ventricular fibrillation

PubMed Central

Anantharaman, Venkataraman; Wan, Paul Weng; Tay, Seow Yian; Manning, Peter George; Lim, Swee Han; Chua, Siang Jin Terrance; Mohan, Tiru; Rabind, Antony Charles; Vidya, Sudarshan; Hao, Ying

2017-01-01

INTRODUCTION Peak currents are the final arbiter of defibrillation in patients with ventricular fibrillation (VF). However, biphasic defibrillators continue to use energy in joules for electrical conversion in hopes that their impedance compensation properties will address transthoracic impedance (TTI), which must be overcome when a fixed amount of energy is delivered. However, optimal peak currents for conversion of VF remain unclear. We aimed to determine the role of peak current and optimal peak levels for conversion in collapsed VF patients. METHODS Adult, non-pregnant patients presenting with non-traumatic VF were included in the study. All defibrillations that occurred were included. Impedance values during defibrillation were used to calculate peak current values. The endpoint was return of spontaneous circulation (ROSC). RESULTS Of the 197 patients analysed, 105 had ROSC. Characteristics of patients with and without ROSC were comparable. Short duration of collapse < 10 minutes correlated positively with ROSC. Generally, patients with average or high TTI converted at lower peak currents. 25% of patients with high TTI converted at 13.3 ± 2.3 A, 22.7% with average TTI at 18.2 ± 2.5 A and 18.6% with low TTI at 27.0 ± 4.7 A (p = 0.729). Highest peak current conversions were at < 15 A and 15–20 A. Of the 44 patients who achieved first-shock ROSC, 33 (75.0%) received < 20 A peak current vs. > 20 A for the remaining 11 (25%) patients (p = 0.002). CONCLUSION For best effect, priming biphasic defibrillators to deliver specific peak currents should be considered. PMID:28741007

Linkage to 10q22 for maximum intraocular pressure and 1p32 for maximum cup-to-disc ratio in an extended primary open-angle glaucoma pedigree.

PubMed

Charlesworth, Jac C; Dyer, Thomas D; Stankovich, Jim M; Blangero, John; Mackey, David A; Craig, Jamie E; Green, Catherine M; Foote, Simon J; Baird, Paul N; Sale, Michèle M

2005-10-01

The purpose of this study was to identify genetic contributions to primary open-angle glaucoma (POAG) through investigations of two quantitative components of the POAG phenotype. Genome-wide multipoint variance-components linkage analyses of maximum recorded intraocular pressure (IOP) and maximum vertical cup-to-disc ratio were conducted on data from a single, large Australian POAG pedigree that has been found to segregate the myocilin Q368X mutation in some individuals. Multipoint linkage analysis of maximum recorded IOP produced a peak LOD score of 3.3 (P = 0.00015) near marker D10S537 on 10q22, whereas the maximum cup-to-disc ratio produced a peak LOD score of 2.3 (P = 0.00056) near markers D1S197 to D1S220 on 1p32. Inclusion of the myocilin Q368X mutation as a covariate provided evidence of an interaction between this mutation and the IOP and cup-to-disc ratio loci. Significant linkage has been identified for maximum IOP and suggestive linkage for vertical cup-to-disc ratio. Identification of genes contributing to the variance of these traits will enhance understanding of the pathophysiology of POAG as a whole.

Survey of Occupational Noise Exposure in CF Personnel in Selected High-Risk Trades

DTIC Science & Technology

2003-11-01

peak, maximum level , minimum level , average sound level , time weighted average, dose, projected 8-hour dose, and upper limit time were measured for...10 4.4.2 Maximum Sound Level ...11 4.4.3 Minimum Sound Level

CORRIGENDUM of the MJO Transition from Shallow to Deep Convection in Cloudsat-Calipso Data and GISS GCM Simulations

NASA Technical Reports Server (NTRS)

Del Genio, Anthony; Chen, Yonghua; Kim, Daehyun; Yao, Mao-Sung

2015-01-01

We have identified several errors in the calculations that were performed to create Fig. 3 of Del Genio et al. (2012). These errors affect the composite evolution of precipitation and column water vapor versus lag relative to the Madden-Julian oscillation (MJO) peak presented in that figure. The precipitation and column water vapor data for the April and November 2009 MJO events were composited incorrectly because the date of the MJO peak at a given longitude was assigned to the incorrect longitude band. In addition, the precipitation data for all MJO events were first accumulated daily and the daily accumulations averaged at each lag to create the composite, rather than the averaging of instantaneous values that was used for other composite figures in the paper. One poorly sampled day in the west Pacific therefore biases the composite precipitation in that region at several lags after the MJO peak. Finally, a 4-day running mean was mistakenly applied to the precipitation and column water vapor data rather than the intended 5-day running mean. The results of the corrections are that an anomalous west Pacific precipitation maximum510 days after the MJO peak is removed and the maximum in west Pacific precipitation one pentad before the MJO peak is now more evident; there is now a clear maximum in precipitation for the entire warm pool one pentad before the MJO peak; west Pacific column water vapor now varies more strongly as a function of lag relative to the peak; and precipitation, and to a lesser extent column water vapor, in general vary more smoothly with time. The corrections do not affect any other parts of the paper nor do they change the scientific conclusions we reached. The 4-day running mean error also affects Figs. 1 and 2 therein, with almost imperceptible impacts that do not affect any results or necessitate major changes to the text.

Vibrational dynamics and boson peak in a supercooled polydisperse liquid.

PubMed

Abraham, Sneha Elizabeth; Bagchi, Biman

2010-03-01

Vibrational density of states (VDOS) in a supercooled polydisperse liquid is computed by diagonalizing the Hessian matrix evaluated at the potential energy minima for systems with different values of polydispersity. An increase in polydispersity leads to an increase in the relative population of localized high-frequency modes. At low frequencies, the density of states shows an excess compared to the Debye squared-frequency law, which has been identified with the boson peak. The height of the boson peak increases with polydispersity and shows a rather narrow sensitivity to changes in temperature. While the modes comprising the boson peak appear to be largely delocalized, there is a sharp drop in the participation ratio of the modes that exist just below the boson peak indicative of the quasilocalized nature of the low-frequency vibrations. Study of the difference spectrum at two different polydispersity reveals that the increase in the height of boson peak is due to a population shift from modes with frequencies above the maximum in the VDOS to that below the maximum, indicating an increase in the fraction of the unstable modes in the system. The latter is further supported by the facilitation of the observed dynamics by polydispersity. Since the strength of the liquid increases with polydispersity, the present result provides an evidence that the intensity of boson peak correlates positively with the strength of the liquid, as observed earlier in many experimental systems.

An Evaluation of Selected Extraordinary Floods in the United States Reported by the U.S. Geological Survey and Implications for Future Advancement of Flood Science

USGS Publications Warehouse

Costa, John E.; Jarrett, Robert D.

2008-01-01

Thirty flood peak discharges determine the envelope curve of maximum floods documented in the United States by the U.S. Geological Survey. These floods occurred from 1927 to 1978 and are extraordinary not just in their magnitude, but in their hydraulic and geomorphic characteristics. The reliability of the computed discharge of these extraordinary floods was reviewed and evaluated using current (2007) best practices. Of the 30 flood peak discharges investigated, only 7 were measured at daily streamflow-gaging stations that existed when the flood occurred, and 23 were measured at miscellaneous (ungaged) sites. Methods used to measure these 30 extraordinary flood peak discharges consisted of 21 slope-area measurements, 2 direct current-meter measurements, 1 culvert measurement, 1 rating-curve extension, and 1 interpolation and rating-curve extension. The remaining four peak discharges were measured using combinations of culvert, slope-area, flow-over-road, and contracted-opening measurements. The method of peak discharge determination for one flood is unknown. Changes to peak discharge or rating are recommended for 20 of the 30 flood peak discharges that were evaluated. Nine floods retained published peak discharges, but their ratings were downgraded. For two floods, both peak discharge and rating were corrected and revised. Peak discharges for five floods that are subject to significant uncertainty due to complex field and hydraulic conditions, were re-rated as estimates. This study resulted in 5 of the 30 peak discharges having revised values greater than about 10 percent different from the original published values. Peak discharges were smaller for three floods (North Fork Hubbard Creek, Texas; El Rancho Arroyo, New Mexico; South Fork Wailua River, Hawaii), and two peak discharges were revised upward (Lahontan Reservoir tributary, Nevada; Bronco Creek, Arizona). Two peak discharges were indeterminate because they were concluded to have been debris flows with peak discharges that were estimated by an inappropriate method (slope-area) (Big Creek near Waynesville, North Carolina; Day Creek near Etiwanda, California). Original field notes and records could not be found for three of the floods, however, some data (copies of original materials, records of reviews) were available for two of these floods. A rating was assigned to each of seven peak discharges that had no rating. Errors identified in the reviews include misidentified flow processes, incorrect drainage areas for very small basins, incorrect latitude and longitude, improper field methods, arithmetic mistakes in hand calculations, omission of measured high flows when developing rating curves, and typographical errors. Common problems include use of two-section slope-area measurements, poor site selection, uncertainties in Manning's n-values, inadequate review, lost data files, and insufficient and inadequately described high-water marks. These floods also highlight the extreme difficulty in making indirect discharge measurements following extraordinary floods. Significantly, none of the indirect measurements are rated better than fair, which indicates the need to improve methodology to estimate peak discharge. Highly unsteady flow and resulting transient hydraulic phenomena, two-dimensional flow patterns, debris flows at streamflow-gaging stations, and the possibility of disconnected flow surfaces are examples of unresolved problems not well handled by current indirect discharge methodology. On the basis of a comprehensive review of 50,000 annual peak discharges and miscellaneous floods in California, problems with individual flood peak discharges would be expected to require a revision of discharge or rating curves at a rate no greater than about 0.10 percent of all floods. Many extraordinary floods create complex flow patterns and processes that cannot be adequately documented with quasi-steady, uniform one-dimensional analyses. These floods are most accura

The NASA F-106B Storm Hazards Program

NASA Technical Reports Server (NTRS)

Neely, W. R., Jr.; Fisher, B. D.

1983-01-01

During the NASA LRC Storm Hazards Program, 698 thunderstorm precipitations were made from 1980 to 1983 with an F-106B aircraft in order to record direct lightning strike data and the associated flight conditions. It was found that each of the three composite fin caps tested experienced multiple lightning attachments with only minor cosmetic damage. The maximum current level was only 20 ka, which is well below the design standard of 200 ka; however, indications are that the current rate of rise standard has been approached and may be exceeded in a major strike. The peak lightning strike rate occurred at ambient temperatures between -40 and -45 C, while most previously reported strikes have occurred at or near the freezing level. No significant operational difficulties or major aircraft damage resulting from the thunderstorm penetrations have been found.

Superconducting characteristics in purified tantalum-foils

NASA Astrophysics Data System (ADS)

Hu, Qinghua; Wang, Zhihe

2018-07-01

We have conducted extensive investigations on the electrical transport and magnetization on a purified tantalum foil with extremely sharp resistive transition (transition width ΔTc < 0.02 K) at 0 T and residual resistivity ratio ρ290K/ρ5K= 16.75. Many effects, such as anisotropic field-induced resistive broadening and second peak of the magnetization-hysteresis loop, are observed in the sample. The maximum upper critical field determined by criteria of R/Rn = 0.9 is about 1.08 T rather weak compared to that in cuprate and/or iron-based superconductors. Although the value of upper critical field Hc2(0) and the field dependence of effective pinning energy U show that the flux pinning potential is weaker, the critical current density Jc(2 K, 0 T) = 1.145 × 105 A/cm2 and the effect of second peak indicate that there should be higher collective vortex pinning potential in the tantalum foil. The carriers are dominated by holes with the density n = 6.6 × 1022/cm3.

Space charge effect in spectrometers of ion mobility increment with planar drift chamber.

PubMed

Elistratov, A A; Sherbakov, L A

2007-01-01

The effect of space charge on the ion beam in a spectrometer of ion mobility increment with the planar drift chamber has been investigated. A model for the drift of ions under a non-uniform high-frequency electric field(1-3) has been developed recently. We have amplified this model by taking space charge effect into account. The ion peak shape taking into consideration the space charge effect is obtained. The output current saturation effect limiting the rise of the ion peak with increasing ion density at the input of the drift chamber of a spectrometer is observed. We show that the saturation effect is caused by the following phenomenon. The maximum possible output ion density exists, depending on the ion type (constant ion mobility, k(0)) and the time of the motion of ions through the drift chamber. At the same time, the ion density does not depend on the parameters of the drift chamber.

Development of flood regressions and climate change scenarios to explore estimates of future peak flows

USGS Publications Warehouse

Burns, Douglas A.; Smith, Martyn J.; Freehafer, Douglas A.

2015-12-31

The application uses predictions of future annual precipitation from five climate models and two future greenhouse gas emissions scenarios and provides results that are averaged over three future periods—2025 to 2049, 2050 to 2074, and 2075 to 2099. Results are presented in ensemble form as the mean, median, maximum, and minimum values among the five climate models for each greenhouse gas emissions scenario and period. These predictions of future annual precipitation are substituted into either the precipitation variable or a water balance equation for runoff to calculate potential future peak flows. This application is intended to be used only as an exploratory tool because (1) the regression equations on which the application is based have not been adequately tested outside the range of the current climate and (2) forecasting future precipitation with climate models and downscaling these results to a fine spatial resolution have a high degree of uncertainty. This report includes a discussion of the assumptions, uncertainties, and appropriate use of this exploratory application.

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

Abliz, M.; Grimmer, J.; Dejus, R.

The current design of the Advanced Photon Source Upgrade (APS-U) project is a multi-bend achromat (MBA) lattice, which incorporates three-pole wigglers as radiation sources for the bending magnet beamlines. They are located in the short section between the M4 dipole and Q8 quadrupole magnets. Due to space constraints, a hybrid permanent magnet design is necessary to provide the required magnetic field strength. A three-pole wiggler with a flat peak field profile along the beam axis was designed to enhance the photon flux and flatten the transverse flux density distributions. The magnetic peak field at the center pole reached 1.08 Teslamore » for a magnetic gap of 26 mm. The maximum power density, integrated over all vertical angles, is 3.1 W/mm 2, which is substantially higher than that of the existing bending magnets at the APS (0.86 W/mm 2). Detailed designs of the three-pole wiggler is presented, including calculated spectral-angular flux distributions.« less

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

Abliz, M., E-mail: mabliz@aps.anl.gov; Grimmer, J., E-mail: grimmer@aps.anl.gov; Dejus, R.

The current design of the Advanced Photon Source Upgrade (APS-U) project is a multi-bend achromat (MBA) lattice, which incorporates three-pole wigglers as radiation sources for the bending magnet beamlines. They are located in the short section between the M4 dipole and Q8 quadrupole magnets. Due to space constraints, a hybrid permanent magnet design is necessary to provide the required magnetic field strength. A three-pole wiggler with a flat peak field profile along the beam axis was designed to enhance the photon flux and flatten the transverse flux density distributions. The magnetic peak field at the center pole reached 1.08 Teslamore » for a magnetic gap of 26 mm. The maximum power density, integrated over all vertical angles, is 3.1 W/mm{sup 2}, which is substantially higher than that of the existing bending magnets at the APS (0.86 W/mm{sup 2}). Detailed designs of the three-pole wiggler is presented, including calculated spectral-angular flux distributions.« less

IRI STORM validation over Europe

NASA Astrophysics Data System (ADS)

Haralambous, Haris; Vryonides, Photos; Demetrescu, Crişan; Dobrică, Venera; Maris, Georgeta; Ionescu, Diana

2014-05-01

The International Reference Ionosphere (IRI) model includes an empirical Storm-Time Ionospheric Correction Model (STORM) extension to account for storm-time changes of the F layer peak electron density (NmF2) during increased geomagnetic activity. This model extension is driven by past history values of the geomagnetic index ap (The magnetic index applied is the integral of ap over the previous 33 hours with a weighting function deduced from physically based modeling) and it adjusts the quiet-time F layer peak electron density (NmF2) to account for storm-time changes in the ionosphere. In this investigation manually scaled hourly values of NmF2 measured during the main and recovery phases of selected storms for the maximum solar activity period of the current solar cycle are compared with the predicted IRI-2012 NmF2 over European ionospheric stations using the STORM model option. Based on the comparison a subsequent performance evaluation of the STORM option during this period is quantified.

Optimization of OT-MACH Filter Generation for Target Recognition

NASA Technical Reports Server (NTRS)

Johnson, Oliver C.; Edens, Weston; Lu, Thomas T.; Chao, Tien-Hsin

2009-01-01

An automatic Optimum Trade-off Maximum Average Correlation Height (OT-MACH) filter generator for use in a gray-scale optical correlator (GOC) has been developed for improved target detection at JPL. While the OT-MACH filter has been shown to be an optimal filter for target detection, actually solving for the optimum is too computationally intensive for multiple targets. Instead, an adaptive step gradient descent method was tested to iteratively optimize the three OT-MACH parameters, alpha, beta, and gamma. The feedback for the gradient descent method was a composite of the performance measures, correlation peak height and peak to side lobe ratio. The automated method generated and tested multiple filters in order to approach the optimal filter quicker and more reliably than the current manual method. Initial usage and testing has shown preliminary success at finding an approximation of the optimal filter, in terms of alpha, beta, gamma values. This corresponded to a substantial improvement in detection performance where the true positive rate increased for the same average false positives per image.

Floods of January-February 1959 in Indiana

USGS Publications Warehouse

Hale, Malcolm D.; Hoggatt, Richard Earl

1961-01-01

Previous maximum stages during the period of record were exceeded at 26 gaging stations. The peak discharge of Big Indian Creek near Corydon, and peak stages of Laughery Creek near Farmers Retreat and Vernon Fork at Vernon on January 21, were greater than any since at least 1897. The peak stage of Wabash River at Huntington on February 10 exceeded that of the historical 1913 flood by 0.5 foot.

In Vivo potassium-39 NMR spectra by the burg maximum-entropy method

NASA Astrophysics Data System (ADS)

Uchiyama, Takanori; Minamitani, Haruyuki

The Burg maximum-entropy method was applied to estimate 39K NMR spectra of mung bean root tips. The maximum-entropy spectra have as good a linearity between peak areas and potassium concentrations as those obtained by fast Fourier transform and give a better estimation of intracellular potassium concentrations. Therefore potassium uptake and loss processes of mung bean root tips are shown to be more clearly traced by the maximum-entropy method.

The effect of motorcycle helmet fit on estimating head impact kinematics from residual liner crush.

PubMed

Bonin, Stephanie J; Gardiner, John C; Onar-Thomas, Arzu; Asfour, Shihab S; Siegmund, Gunter P

2017-09-01

Proper helmet fit is important for optimizing head protection during an impact, yet many motorcyclists wear helmets that do not properly fit their heads. The goals of this study are i) to quantify how a mismatch in headform size and motorcycle helmet size affects headform peak acceleration and head injury criteria (HIC), and ii) to determine if peak acceleration, HIC, and impact speed can be estimated from the foam liner's maximum residual crush depth or residual crush volume. Shorty-style helmets (4 sizes of a single model) were tested on instrumented headforms (4 sizes) during linear impacts between 2.0 and 10.5m/s to the forehead region. Helmets were CT scanned to quantify residual crush depth and volume. Separate linear regression models were used to quantify how the response variables (peak acceleration (g), HIC, and impact speed (m/s)) were related to the predictor variables (maximum crush depth (mm), crush volume (cm 3 ), and the difference in circumference between the helmet and headform (cm)). Overall, we found that increasingly oversized helmets reduced peak headform acceleration and HIC for a given impact speed for maximum residual crush depths less than 7.9mm and residual crush volume less than 40cm 3 . Below these levels of residual crush, we found that peak headform acceleration, HIC, and impact speed can be estimated from a helmet's residual crush. Above these crush thresholds, large variations in headform kinematics are present, possibly related to densification of the foam liner during the impact. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of patella bone strain between females with and without patellofemoral pain: a finite element analysis study.

PubMed

Ho, Kai-Yu; Keyak, Joyce H; Powers, Christopher M

2014-01-03

Elevated bone principal strain (an indicator of potential bone injury) resulting from reduced cartilage thickness has been suggested to contribute to patellofemoral symptoms. However, research linking patella bone strain, articular cartilage thickness, and patellofemoral pain (PFP) remains limited. The primary purpose was to determine whether females with PFP exhibit elevated patella bone strain when compared to pain-free controls. A secondary objective was to determine the influence of patella cartilage thickness on patella bone strain. Ten females with PFP and 10 gender, age, and activity-matched pain-free controls participated. Patella bone strain fields were quantified utilizing subject-specific finite element (FE) models of the patellofemoral joint (PFJ). Input parameters for the FE model included (1) PFJ geometry, (2) elastic moduli of the patella bone, (3) weight-bearing PFJ kinematics, and (4) quadriceps muscle forces. Using quasi-static simulations, peak and average minimum principal strains as well as peak and average maximum principal strains were quantified. Cartilage thickness was quantified by computing the perpendicular distance between opposing voxels defining the cartilage edges on axial plane magnetic resonance images. Compared to the pain-free controls, individuals with PFP exhibited increased peak and average minimum and maximum principal strain magnitudes in the patella. Additionally, patella cartilage thickness was negatively associated with peak minimum principal patella strain and peak maximum principal patella strain. The elevated bone strain magnitudes resulting from reduced cartilage thickness may contribute to patellofemoral symptoms and bone injury in persons with PFP. © 2013 Published by Elsevier Ltd.

Seasonal Variation in Meteor Decay Time Profiles Measured by a Meteor Radar at King Sejong Station (62°S, 58°W), Antarctica

NASA Astrophysics Data System (ADS)

Kim, Y.; Kim, J.; Lee, C.; Jee, G.

2008-12-01

A VHF meteor radar at King Sejong Station (62°S, 58°W), Antarctica has been detecting echoes from more than 20,000 meteors per day since March 2007. Meteor echoes are decayed typically within seconds as meteor trail plasma spread away or are neutralized. Assuming that diffusion is the only process for decay of meteor echo signals, the atmospheric temperatures and pressures have been inferred from the measured meteor decay times at the peak meteor altitudes around 90 km. In this study, we analyze altitude profiles of meteor decay times in each month, which clearly show a maximum at 80 ~ 85 km. The maximum appears at higher altitude during austral summer than winter. The fast decay of meteor signals below the maximum cannot be explained by atmospheric diffusion which decreases with increasing atmospheric densities. We find that the measured meteor decay time profiles can be fitted with a loss rate profile, in addition to diffusion, with a peak altitude of 55 ~ 73 km and a peak rate of 4 ~ 15 sec- 1. The additional loss of meteor plasma may be due to electron absorption by icy particles in the mesosphere, but the estimated peak altitudes are much lower than the layers of NLC or PME. The estimated peak loss rates seem to be too large to be accounted by absorption by icy or dust particles. We will discuss other processes to explain the fast meteor times and their variation over season.

Evaluation of the dependence of the exposure dose on the attenuation correction in brain PET/CT scans using 18F-FDG

NASA Astrophysics Data System (ADS)

Choi, Eun-Jin; Jeong, Moon-Taeg; Jang, Seong-Joo; Choi, Nam-Gil; Han, Jae-Bok; Yang, Nam-Hee; Dong, Kyung-Rae; Chung, Woon-Kwan; Lee, Yun-Jong; Ryu, Young-Hwan; Choi, Sung-Hyun; Seong, Kyeong-Jeong

2014-01-01

This study examined whether scanning could be performed with minimum dose and minimum exposure to the patient after an attenuation correction. A Hoffman 3D Brain Phantom was used in BIO_40 and D_690 PET/CT scanners, and the CT dose for the equipment was classified as a low dose (minimum dose), medium dose (general dose for scanning) and high dose (dose with use of contrast medium) before obtaining the image at a fixed kilo-voltage-peak (kVp) and milliampere (mA) that were adjusted gradually in 17-20 stages. A PET image was then obtained to perform an attenuation correction based on an attenuation map before analyzing the dose difference. Depending on tube current in the range of 33-190 milliampere-second (mAs) when BIO_40 was used, a significant difference in the effective dose was observed between the minimum and the maximum mAs (p < 0.05). According to a Scheffe post-hoc test, the ratio of the minimum to the maximum of the effective dose was increased by approximately 5.26-fold. Depending on the change in the tube current in the range of 10-200 mA when D_690 was used, a significant difference in the effective dose was observed between the minimum and the maximum of mA (p < 0.05). The Scheffe posthoc test revealed a 20.5-fold difference. In conclusion, because effective exposure dose increases with increasing operating current, it is possible to reduce the exposure limit in a brain scan can be reduced if the CT dose can be minimized for a transmission scan.

Inter-individual similarities and variations in muscle forces acting on the ankle joint during gait.

PubMed

Błażkiewicz, Michalina; Wiszomirska, Ida; Kaczmarczyk, Katarzyna; Naemi, Roozbeh; Wit, Andrzej

2017-10-01

Muscle forces acting over the ankle joint play an important role in the forward progression of the body during gait. Yet despite the importance of ankle muscle forces, direct in-vivo measurements are neither possible nor practical. This makes musculoskeletal simulation useful as an indirect technique to quantify the muscle forces at work during locomotion. The purpose of this study was to: 1) identify the maximum peaks of individual ankle muscle forces during gait; 2) investigate the order over which the muscles are sorted based on their maximum peak force. Three-dimensional kinematics and ground reaction forces were measured during the gait of 10 healthy subjects, and the data so obtained were input into the musculoskeletal model distributed with the OpenSim software. In all 10 individuals we observed that the soleus muscle generated the greatest strength both in dynamic (1856.1N) and isometric (3549N) conditions, followed by the gastrocnemius in dynamic conditions (1232.5N). For all other muscles, however, the sequence looks different across subjects, so the k-means clustering method was used to obtain one main order over which the muscles' peak-forces are sorted. The results indicate a common theme, with some variations in the maximum peaks of ankle muscle force across subjects. Copyright © 2017 Elsevier B.V. All rights reserved.

A new maximum power tracking in PV system during partially shaded conditions based on shuffled frog leap algorithm

NASA Astrophysics Data System (ADS)

Sridhar, R.; Jeevananthan, S.; Dash, S. S.; Vishnuram, Pradeep

2017-05-01

Maximum Power Point Trackers (MPPTs) are power electronic conditioners used in photovoltaic (PV) system to ensure that PV structures feed maximum power for the given ambient temperature and sun's irradiation. When the PV panels are shaded by a fraction due to any environment hindrances then, conventional MPPT trackers may fail in tracking the appropriate peak power as there will be multi power peaks. In this work, a shuffled frog leap algorithm (SFLA) is proposed and it successfully identifies the global maximum power point among other local maxima. The SFLA MPPT is compared with a well-entrenched conventional perturb and observe (P&O) MPPT algorithm and a global search particle swarm optimisation (PSO) MPPT. The simulation results reveal that the proposed algorithm is highly advantageous than P&O, as it tracks nearly 30% more power for a given shading pattern. The credible nature of the proposed SFLA is ensured when it outplays PSO MPPT in convergence. The whole system is realised in MATLAB/Simulink environment.

Average current is better than peak current as therapeutic dosage for biphasic waveforms in a ventricular fibrillation pig model of cardiac arrest.

PubMed

Chen, Bihua; Yu, Tao; Ristagno, Giuseppe; Quan, Weilun; Li, Yongqin

2014-10-01

Defibrillation current has been shown to be a clinically more relevant dosing unit than energy. However, the effects of average and peak current in determining shock outcome are still undetermined. The aim of this study was to investigate the relationship between average current, peak current and defibrillation success when different biphasic waveforms were employed. Ventricular fibrillation (VF) was electrically induced in 22 domestic male pigs. Animals were then randomized to receive defibrillation using one of two different biphasic waveforms. A grouped up-and-down defibrillation threshold-testing protocol was used to maintain the average success rate of 50% in the neighborhood. In 14 animals (Study A), defibrillations were accomplished with either biphasic truncated exponential (BTE) or rectilinear biphasic waveforms. In eight animals (Study B), shocks were delivered using two BTE waveforms that had identical peak current but different waveform durations. Both average and peak currents were associated with defibrillation success when BTE and rectilinear waveforms were investigated. However, when pathway impedance was less than 90Ω for the BTE waveform, bivariate correlation coefficient was 0.36 (p=0.001) for the average current, but only 0.21 (p=0.06) for the peak current in Study A. In Study B, a high defibrillation success (67.9% vs. 38.8%, p<0.001) was observed when the waveform delivered more average current (14.9±2.1A vs. 13.5±1.7A, p<0.001) while keeping the peak current unchanged. In this porcine model of VF, average current was better than peak current to be an adequate parameter to describe the therapeutic dosage when biphasic defibrillation waveforms were used. The institutional protocol number: P0805. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Combining axial and radial nanowire heterostructures: radial Esaki diodes and tunnel field-effect transistors.

PubMed

Dey, Anil W; Svensson, Johannes; Ek, Martin; Lind, Erik; Thelander, Claes; Wernersson, Lars-Erik

2013-01-01

The ever-growing demand on high-performance electronics has generated transistors with very impressive figures of merit (Radosavljevic et al., IEEE Int. Devices Meeting 2009, 1-4 and Cho et al., IEEE Int. Devices Meeting 2011, 15.1.1-15.1.4). The continued scaling of the supply voltage of field-effect transistors, such as tunnel field-effect transistors (TFETs), requires the implementation of advanced transistor architectures including FinFETs and nanowire devices. Moreover, integration of novel materials with high electron mobilities, such as III-V semiconductors and graphene, are also being considered to further enhance the device properties (del Alamo, Nature 2011, 479, 317-323, and Liao et al., Nature 2010, 467, 305-308). In nanowire devices, boosting the drive current at a fixed supply voltage or maintaining a constant drive current at a reduced supply voltage may be achieved by increasing the cross-sectional area of a device, however at the cost of deteriorated electrostatics. A gate-all-around nanowire device architecture is the most favorable electrostatic configuration to suppress short channel effects; however, the arrangement of arrays of parallel vertical nanowires to address the drive current predicament will require additional chip area. The use of a core-shell nanowire with a radial heterojunction in a transistor architecture provides an attractive means to address the drive current issue without compromising neither chip area nor device electrostatics. In addition to design advantages of a radial transistor architecture, we in this work illustrate the benefit in terms of drive current per unit chip area and compare the experimental data for axial GaSb/InAs Esaki diodes and TFETs to their radial counterparts and normalize the electrical data to the largest cross-sectional area of the nanowire, i.e. the occupied chip area, assuming a vertical device geometry. Our data on lateral devices show that radial Esaki diodes deliver almost 7 times higher peak current, Jpeak = 2310 kA/cm(2), than the maximum peak current of axial GaSb/InAs(Sb) Esaki diodes per unit chip area. The radial TFETs also deliver high peak current densities Jpeak = 1210 kA/cm(2), while their axial counterparts at most carry Jpeak = 77 kA/cm(2), normalized to the largest cross-sectional area of the nanowire.

SWIFT OBSERVATIONS OF GAMMA-RAY BURST PULSE SHAPES: GRB PULSE SPECTRAL EVOLUTION CLARIFIED

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

Hakkila, Jon; Lien, Amy; Sakamoto, Takanori

Isolated Swift gamma-ray burst (GRB) pulses, like their higher-energy BATSE counterparts, emit the bulk of their pulsed emission as a hard-to-soft component that can be fitted by the Norris et al. empirical pulse model. This signal is overlaid by a fainter, three-peaked signal that can be modeled by the residual fit of Hakkila and Preece: the two fits combine to reproduce GRB pulses with distinctive three-peaked shapes. The precursor peak appears on or before the pulse rise and is often the hardest component, the central peak is the brightest, and the decay peak converts exponentially decaying emission into a long,more » soft, power-law tail. Accounting for systematic instrumental differences, the general characteristics of the fitted pulses are remarkably similar. Isolated GRB pulses are dominated by hard-to-soft evolution; this is more pronounced for asymmetric pulses than for symmetric ones. Isolated GRB pulses can also exhibit intensity tracking behaviors that, when observed, are tied to the timing of the three peaks: pulses with the largest maximum hardnesses are hardest during the precursor, those with smaller maximum hardnesses are hardest during the central peak, and all pulses can re-harden during the central peak and/or during the decay peak. Since these behaviors are essentially seen in all isolated pulses, the distinction between “hard-to-soft and “intensity-tracking” pulses really no longer applies. Additionally, the triple-peaked nature of isolated GRB pulses seems to indicate that energy is injected on three separate occasions during the pulse duration: theoretical pulse models need to account for this.« less

A High Peak Current Source for the CEBAF Injector

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

Yunn, Byung; Sinclair, Charles; Krafft, Geoffrey

1992-07-01

The CEBAF accelerator can drive high power IR and UV FELs, if a high peak current source is added to the existing front end. We present a design for a high peak current injector which is compatible with simultaneous operation of the accelerator for cw nulear physics (NP) beam. The high peak current injector provides 60 A peak current in 2 psec long bunches carrying 120 pC charge at 7.485 MHz. At 10 MeV that beam is combined with 5 MeV NP beam (0.13pC, 2 psec long bunches at 1497 MHz) in an energy combination chicane for simultaneous acceleration inmore » the injector linac. The modifications to the low-energy NP transport are described. Results of optical and beam dynamics calculations for both high peak current and NP beams in combined operation are presented.« less

Spectral properties of the association nanoparticle system of ciprofloxacin-phloxine and its application to fluorescence analysis.

PubMed

Zou, Jieming; Jiang, Zhiliang; Wang, Lisheng; Li, Tingsheng; Liu, Qinye

2004-06-01

There is a fluorescence peak at 570 nm, and a maximum absorption peak at 560 nm for phloxine (PHLO) in a pH 7 water solution. Under these conditions, the ciprofloxacin cation (CPFX+) and PHLO- combine into hydrophobic CPFX-PHLO association molecule by means of static gravitation. There are stronger van der Waals forces and hydrophobic forces among the CPFX-PHLO molecules. Thus, they aggregate automatically to the (CPFX-PHLO)n association nanoparticle in red-violet color. That was characterized by scan electron microscopy (SEM), hyperfiltration and dialysis tests. In 0.04 M HCl, the red-violet nanoparticles exhibited a Rayleigh scattering peak at 470 nm, a resonance scattering peak at 580 nm, a maximum absorption wavelength at 565 nm, and a fluorescence peak at 450 nm. The fluorescence analytical conditions of CPFX have been considered. The CPFX concentration in the range of 1.0 x 10(-6)-4.0 x 10(-5) M is linear to the fluorescence intensity, F450nm. The detection limit was achieved at 4.0 x 10(-7) M CPFX. The CPFX in real samples was determined with satisfactory results.

Cellulose polymorphy, crystallite size, and the Segal crystallinity index

USDA-ARS?s Scientific Manuscript database

The X-ray diffraction-based Segal Crystallinity Index (CI) was calculated for simulated different sizes of crystallites for cellulose I' and II. The Mercury software was used, and different crystallite sizes were based on different input peak widths at half of the maximum peak intensity (pwhm). The ...

Flood of August 2, 1972, in the Little Maquoketa River basin, Dubuque County, Iowa

USGS Publications Warehouse

Heinitz, Albert J.

1973-01-01

Flood-peak discharges at 12 sites, basin rainfall, a description of the 1972 flood, brief accounts of other major floods in the basin, maximum flood peaks in northeastern Iowa, selected flood-frequency data, and annual floods of record at 5 sites are given.

Determination of adsorption isotherms of chlorinated hydrocarbons on halloysite adsorbent by inverse gas chromatography.

PubMed

Czech, K; Słomkiewicz, P M

2013-05-03

Inverse gas chromatographic methods of isotherm determination peak maximum (PM) and peak division (PD) were compared. These methods were applied to determine adsorption isotherms of dichloroethylene, trichloroethylene and tetrachloroethylene on acid-activated halloysite and adsorption enthalpy. Copyright © 2013 Elsevier B.V. All rights reserved.

Laser pulse heating of steel mixing with WC particles in a irradiated region

NASA Astrophysics Data System (ADS)

Shuja, S. Z.; Yilbas, B. S.; Ali, H.; Karatas, C.

2016-12-01

Laser pulse heating of steel mixing with tungsten carbide (WC) particles is carried out. Temperature field in the irradiated region is simulated in line with the experimental conditions. In the analysis, a laser pulse parameter is introduced, which defines the laser pulse intensity distribution at the irradiated surface. The influence of the laser parameter on the melt pool size and the maximum temperature increase in the irradiated region is examined. Surface temperature predictions are compared with the experimental data. In addition, the distribution of WC particles and their re-locations in the treated layer, due to combination of the natural convection and Marangoni currents, are predicted. The findings are compared to the experimental data. It is found that surface temperature predictions agree well with the experimental data. The dislocated WC particles form a streamlining in the near region of the melt pool wall, which agree with the experimental findings. The Gaussian distribution of the laser pulse intensity results in the maximum peak temperature and the maximum flow velocity inside the melt pool. In this case, the melt pool depth becomes the largest as compared to those corresponding to other laser pulse intensity distributions at the irradiated surface.

Lidar measurements of mesospheric temperature inversion at a low latitude

NASA Astrophysics Data System (ADS)

Siva Kumar, V.; Bhavani Kumar, Y.; Raghunath, K.; Rao, P. B.; Krishnaiah, M.; Mizutani, K.; Aoki, T.; Yasui, M.; Itabe, T.

2001-08-01

The Rayleigh lidar data collected on 119 nights from March 1998 to February 2000 were used to study the statistical characteristics of the low latitude mesospheric temperature inversion observed over Gadanki (13.5° N, 79.2° E), India. The occurrence frequency of the inversion showed semiannual variation with maxima in the equinoxes and minima in the summer and winter, which was quite different from that reported for the mid-latitudes. The peak of the inversion layer was found to be confined to the height range of 73 to 79 km with the maximum occurrence centered around 76 km, with a weak seasonal dependence that fits well to an annual cycle with a maximum in June and a minimum in December. The magnitude of the temperature deviation associated with the inversion was found to be as high as 32 K, with the most probable value occurring at about 20 K. Its seasonal dependence seems to follow an annual cycle with a maximum in April and a minimum in October. The observed characteristics of the inversion layer are compared with that of the mid-latitudes and discussed in light of the current understanding of the source mechanisms.

Countermovement depth - a variable which clarifies the relationship between the maximum power output and height of a vertical jump.

PubMed

Gajewski, Jan; Michalski, Radosław; Buśko, Krzysztof; Mazur-Różycka, Joanna; Staniak, Zbigniew

2018-01-01

The aim of this study was to identify the determinants of peak power achieved during vertical jumps in order to clarify relationship between the height of jump and the ability to exert maximum power. One hundred young (16.8±1.8 years) sportsmen participated in the study (body height 1.861 ± 0.109 m, body weight 80.3 ± 9.2 kg). Each participant performed three jump tests: countermovement jump (CMJ), akimbo countermovement jump (ACMJ), and spike jump (SPJ). A force plate was used to measure ground reaction force and to determine peak power output. The following explanatory variables were included in the model: jump height, body mass, and the lowering of the centre of mass before launch (countermovement depth). A model was created using multiple regression analysis and allometric scaling. The model was used to calculate the expected power value for each participant, which correlated strongly with real values. The value of the coefficient of determination R2 equalled 0.89, 0.90 and 0.98, respectively, for the CMJ, ACMJ, and SPJ jumps. The countermovement depth proved to be a variable strongly affecting the maximum power of jump. If the countermovement depth remains constant, the relative peak power is a simple function of jump height. The results suggest that the jump height of an individual is an exact indicator of their ability to produce maximum power. The presented model has a potential to be utilized under field condition for estimating the maximum power output of vertical jumps.

Do patients with diabetic neuropathy use a higher proportion of their maximum strength when walking?

PubMed

Brown, Steven J; Handsaker, Joseph C; Bowling, Frank L; Maganaris, Costantinos N; Boulton, Andrew J M; Reeves, Neil D

2014-11-28

Diabetic patients have an altered gait strategy during walking and are known to be at high risk of falling, especially when diabetic peripheral neuropathy is present. This study investigated alterations to lower limb joint torques during walking and related these torques to maximum strength in an attempt to elucidate why diabetic patients are more likely to fall. 20 diabetic patients with moderate/severe peripheral neuropathy (DPN), 33 diabetic patients without peripheral neuropathy (DM), and 27 non-diabetic controls (Ctrl) underwent gait analysis using a motion analysis system and force plates to measure kinetic parameters. Lower limb peak joint torques and joint work done (energy expenditure) were calculated during walking. The ratio of peak joint torques and individual maximum joint strengths (measured on a dynamometer) was then calculated for 59 of the 80 participants to yield the ‘operating strength’ for those participants. During walking DM and DPN patients showed significantly reduced peak torques at the ankle and knee. Maximum joint strengths at the knee were significantly less in both DM and DPN groups than Ctrls, and for the DPN group at the ankle. Operating strengths were significantly higher at the ankle in the DPN group compared to the Ctrls. These findings show that diabetic patients walk with reduced lower limb joint torques; however due to a decrement in their maximum ability at the ankle and knee, their operating strengths are higher. This allows less reserve strength if responding to a perturbation in balance, potentially increasing their risk of falling.

Laboratory Measured Emission Losses of Methyl Isothiocyanate at Pacific Northwest Soil Surface Fumigation Temperatures.

PubMed

Lu, Zhou; Hebert, Vincent R; Miller, Glenn C

2017-02-01

Temperature is a major environmental factor influencing land surface volatilization at the time of agricultural field fumigation. Cooler fumigation soil temperatures relevant to Pacific Northwest (PNW) application practices with metam sodium/potassium should result in appreciably reduced methyl isothiocyanate (MITC) emission rates, thus minimizing off target movement and bystander inhalation exposure. Herein, a series of laboratory controlled flow-through soil column assessments were performed evaluating MITC emissions over the range of cooler temperatures (2-13°C). Assessments were also conducted at the maximum allowed label application temperature of 32°C. All assessments were conducted at registration label-specified field moisture capacity, and no more than 50% cumulative MITC loss was observed over the 2-day post-fumigation timeframe. Three-fold reductions in MITC peak fluxes at cooler PNW application temperatures were observed compared to the label maximum temperature. This study supports current EPA metam sodium/potassium label language that indicates surface fumigations during warmer soil conditions should be discouraged.

Spatiotemporal focusing-based widefield multiphoton microscopy for fast optical sectioning.

PubMed

Cheng, Li-Chung; Chang, Chia-Yuan; Lin, Chun-Yu; Cho, Keng-Chi; Yen, Wei-Chung; Chang, Nan-Shan; Xu, Chris; Dong, Chen Yuan; Chen, Shean-Jen

2012-04-09

In this study, a microscope based on spatiotemporal focusing offering widefield multiphoton excitation has been developed to provide fast optical sectioning images. Key features of this microscope are the integrations of a 10 kHz repetition rate ultrafast amplifier featuring high instantaneous peak power (maximum 400 μJ/pulse at a 90 fs pulse width) and a TE-cooled, ultra-sensitive photon detecting, electron multiplying charge-coupled camera into a spatiotemporal focusing microscope. This configuration can produce multiphoton images with an excitation area larger than 200 × 100 μm² at a frame rate greater than 100 Hz (current maximum of 200 Hz). Brownian motions of fluorescent microbeads as small as 0.5 μm were observed in real-time with a lateral spatial resolution of less than 0.5 μm and an axial resolution of approximately 3.5 μm. Furthermore, second harmonic images of chicken tendons demonstrate that the developed widefield multiphoton microscope can provide high resolution z-sectioning for bioimaging.

The effects of co-administration of benzhexol on the peripheral pharmacokinetics of oral levodopa in young volunteers.

PubMed

Roberts, J; Waller, D G; von Renwick, A G; O'Shea, N; Macklin, B S; Bulling, M

1996-04-01

1. The effects of benzhexol on the absorption and pharmacokinetics of an oral dose of levodopa have been studied in 10 young healthy volunteers. Subjects were given a suspension of levodopa (250 mg) 90 min after either benzhexol (5 mg) or placebo in a randomized cross over design with doses separated by at least 1 week; on each occasion carbidopa was given 1 h before and 5 h after the dose of levodopa. Soluble paracetamol and radiolabelled DTPA were given with the levodopa as markers of gastric emptying. 2. Most subjects showed two peaks in the levodopa plasma concentration-time curve on the placebo day, with the second minor peak occurring 1-2 h after the dose. After benzhexol administration all subjects showed two or more peak levodopa concentrations in plasma. Benzhexol administration caused a significant decrease in the maximum concentration (43%; P < 0.05) of the initial peak and an increase (22%; P < 0.1) in the maximum concentration of the second peak. This change in absorption profile caused by benzhexol significantly altered the ratios of the second peak compared with the initial peak for both the maximum concentrations (P < 0.02) and for the AUC values (P < 0.05). Benzhexol administration did not affect the total AUC of levodopa (7.30 +/- 1.09 vs 7.19 +/- 1.26 micrograms ml-1 h; means +/- s.d.). 3. The plasma concentration-time curves for paracetamol showed similar profiles to those for levodopa and the ratios of the peak concentrations and AUC values for the second peak compared with the initial peak were increased significantly by benzhexol administration (P < 0.05). The total AUC of paracetamol was not affected by benzhexol administration (39.4 +/- 8.2 vs 40.0 +/- 8.9 micrograms ml-1 h; mean +/- s.d.) 4. Benzhexol altered the gastric emptying profile, shown by gamma-scintigraphy, with a reduced extent of initial emptying prior to the establishment of the plateau which is characteristic of levodopa administration in the fasting state. In consequence the ratio of the second to the initial phase of emptying was significantly higher (P < 0.01) following benzhexol treatment. 5. Benzhexol reduces the initial phase of gastric emptying after a dose of levodopa so that there is a decrease in the initial peak and a greater proportion of the dose is absorbed subsequently following the second phase of gastric emptying which occurs approximately 1 h later. Theoretically, this altered concentration-time profile could be an advantage for some patients with Parkinson's disease.

Parameters of triggered-lightning flashes in Florida and Alabama

NASA Astrophysics Data System (ADS)

Fisher, R. J.; Schnetzer, G. H.; Thottappillil, R.; Rakov, V. A.; Uman, M. A.; Goldberg, J. D.

1993-12-01

Channel base currents from triggered lightning were measured at the NASA Kennedy Space Center, Florida, during summer 1990 and at Fort McClellan, Alabama, during summer 1991. Additionally, 16-mm cinematic records with 3- or 5-ms resolution were obtained for all flashes, and streak camera records were obtained for three of the Florida flashes. The 17 flashes analyzed here contained 69 strokes, all lowering negative charge from cloud to ground. Statistics on interstroke interval, no-current interstroke interval, total stroke duration, total stroke charge, total stroke action integral (∫ i2dt), return stroke current wave front characteristics, time to half peak value, and return stroke peak current are presented. Return stroke current pulses, characterized by rise times of the order of a few microseconds or less and peak values in the range of 4 to 38 kA, were found not to occur until after any preceding current at the bottom of the lightning channel fell below the noise level of less than 2 A. Current pulses associated with M components, characterized by slower rise times (typically tens to hundreds of microseconds) and peak values generally smaller than those of the return stroke pulses, occurred during established channel current flow of some tens to some hundreds of amperes. A relatively strong positive correlation was found between return stroke current average rate of rise and current peak. There was essentially no correlation between return stroke current peak and 10-90% rise time or between return stroke peak and the width of the current waveform at half of its peak value. Parameters of the lightning flashes triggered in Florida and Alabama are similar to each other but are different from those of triggered lightning recorded in New Mexico during the 1981 Thunderstorm Research International Program. Continuing currents that follow return stroke current peaks and last for more than 10 ms exhibit a variety of wave shapes that we have subdivided into four categories. All such continuing currents appear to start with a current pulse presumably associated with an M component. A brief summary of lightning parameters important for lightning protection, in a form convenient for practical use, is presented in an appendix.

Adsorption characteristics of sulfur solution by acticarbon against drinking-water toxicosis.

PubMed

Ge, Shengbo; Liu, Zhenling; Furuta, Yuzo; Peng, Wanxi

2017-09-01

Sulfur and ammonia nitrogen are rich nutrient pollutants, after entering water can cause algal blooms, cause eutrophication of water body, the spread of them will not only pollute the environment, destroy the ecological balance, but also harm human health through food chain channels, especially drinking-water toxicosis. Acticarbon can adsorb harmful substances, it was beneficial for people's health. In order to figure out the optimal adsorption condition and the intrinsic change of acticarbon, five chemicals were adsorbed by acticarbon and analyzed by FT-IR. The optimal adsorption condition of Fe 2 (SO 4 ) 3 , Na 2 SO 4 , Na 2 S 2 O 8 , S and Na 2 SO 3 was 9 g/1000 g at 80 min, 21 g/1000 g at 20 min, 15g/1000 g at 20 min, 21 g/1000 g at 60 min and 21 g/1000 g at 100 min, respectively. FT-IR spectra showed that acticarbon had eight characteristic peaks, such as S-S stretch, H 2 O stretch, O-H stretch, -C-H stretch, C 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 O or CC stretch, CH 2 bend, C-H were at 3850 cm -1 , 3740 cm -1 , 3435 cm -1 , 2925 cm -1 , 1630 cm -1 , 1390 cm -1 , 1115 cm -1 , 600 cm -1 , respectively. For FT-IR spectra of Fe 2 (SO 4 ) 3 , the peaks at 3850 cm -1 , 3740 cm -1 , 2925 cm -1 achieved the maximum with 9 g/1000 g at 20 min. For Na 2 SO 4 , the peaks at 2925 cm -1 , 1630 cm -1 , 1390 cm -1 , 1115 cm -1 , 600 cm -1 achieved the maximum with 21 g/1000 g at 120 min. For ones of Na 2 S 2 O 8 , the peaks at 3850 cm -1 , 3740 cm -1 , 1390 cm -1 , 1115 cm -1 , 600 cm -1 , achieved the maximum with 2 g/1000 g at 80 min. For ones of S, the peaks at 3850 cm -1 , 3740 cm -1 , 2925 cm -1 achieved the maximum with 19 g/1000 g at 100 min, the peaks at 1390 cm -1 , 1115 cm -1 , 600 cm -1 achieved the maximum with 19 g/1000 g at 20 min. For FT-IR spectra of Na 2 SO 3 , the peaks at 1630 cm -1 , 1390 cm -1 , 1115 cm -1 , 600 cm -1 achieved the maximum with 2 g/1000 g at 100 min. It provided that acticarbon could adsorb and desulphurize from sulfur solution against drinking-water toxicosis.

High-temperature performance of gallium-nitride-based pin alpha-particle detectors grown on sapphire substrates

NASA Astrophysics Data System (ADS)

Zhu, Zhifu; Zhang, Heqiu; Liang, Hongwei; Tang, Bin; Peng, Xincun; Liu, Jianxun; Yang, Chao; Xia, Xiaochuan; Tao, Pengcheng; Shen, Rensheng; Zou, Jijun; Du, Guotong

2018-06-01

The temperature-dependent radiation-detection performance of an alpha-particle detector that was based on a gallium-nitride (GaN)-based pin structure was studied from 290 K to 450 K. Current-voltage-temperature measurements (I-V-T) of the reverse bias show the exponential dependence of leakage currents on the voltage and temperature. The current transport mechanism of the GaN-based pin diode from the reverse bias I-V fitting was analyzed. The temperature-dependent pulse-height spectra of the detectors were studied using an 241 Am alpha-particle source at a reverse bias of 10 V, and the peak positions shifted from 534 keV at 290 K to 490 keV at 450 K. The variation of full width at half maximum (FWHM) from 282 keV at 290 K to 292 keV at 450 K is almost negligible. The GaN-based pin detectors are highly promising for high-temperature environments up to 450 K.

Magnetic configurations of the tilted current sheets in magnetotail

NASA Astrophysics Data System (ADS)

Shen, C.; Rong, Z. J.; Li, X.; Dunlop, M.; Liu, Z. X.; Malova, H. V.; Lucek, E.; Carr, C.

2008-11-01

In this research, the geometrical structures of tilted current sheet and tail flapping waves have been analysed based on multiple spacecraft measurements and some features of the tilted current sheets have been made clear for the first time. The geometrical features of the tilted current sheet revealed in this investigation are as follows: (1) The magnetic field lines (MFLs) in the tilted current sheet are generally plane curves and the osculating planes in which the MFLs lie are about vertical to the equatorial plane, while the normal of the tilted current sheet leans severely to the dawn or dusk side. (2) The tilted current sheet may become very thin, the half thickness of its neutral sheet is generally much less than the minimum radius of the curvature of the MFLs. (3) In the neutral sheet, the field-aligned current density becomes very large and has a maximum value at the center of the current sheet. (4) In some cases, the current density is a bifurcated one, and the two humps of the current density often superpose two peaks in the gradient of magnetic strength, indicating that the magnetic gradient drift current is possibly responsible for the formation of the two humps of the current density in some tilted current sheets. Tilted current sheets often appear along with tail current sheet flapping waves. It is found that, in the tail flapping current sheets, the minimum curvature radius of the MFLs in the current sheet is rather large with values around 1 RE, while the neutral sheet may be very thin, with its half thickness being several tenths of RE. During the flapping waves, the current sheet is tilted substantially, and the maximum tilt angle is generally larger than 45°. The phase velocities of these flapping waves are several tens km/s, while their periods and wavelengths are several tens of minutes, and several earth radii, respectively. These tail flapping events generally last several hours and occur during quiet periods or periods of weak magnetospheric activity.

Analysis of rapid eye movement periodicity in narcoleptics based on maximum entropy method.

PubMed

Honma, H; Ohtomo, N; Kohsaka, M; Fukuda, N; Kobayashi, R; Sakakibara, S; Nakamura, F; Koyama, T

1999-04-01

We examined REM sleep periodicity in typical narcoleptics and patients who had shown signs of a narcoleptic tetrad without HLA-DRB1*1501/DQB1*0602 or DR2 antigens, using spectral analysis based on the maximum entropy method. The REM sleep period of typical narcoleptics showed two peaks, one at 70-90 min and one at 110-130 min at night, and a single peak at around 70-90 min during the daytime. The nocturnal REM sleep period of typical narcoleptics may be composed of several different periods, one of which corresponds to that of their daytime REM sleep.

Updated Model of the Solar Energetic Proton Environment in Space

NASA Astrophysics Data System (ADS)

Jiggens, Piers; Heynderickx, Daniel; Sandberg, Ingmar; Truscott, Pete; Raukunen, Osku; Vainio, Rami

2018-05-01

The Solar Accumulated and Peak Proton and Heavy Ion Radiation Environment (SAPPHIRE) model provides environment specification outputs for all aspects of the Solar Energetic Particle (SEP) environment. The model is based upon a thoroughly cleaned and carefully processed data set. Herein the evolution of the solar proton model is discussed with comparisons to other models and data. This paper discusses the construction of the underlying data set, the modelling methodology, optimisation of fitted flux distributions and extrapolation of model outputs to cover a range of proton energies from 0.1 MeV to 1 GeV. The model provides outputs in terms of mission cumulative fluence, maximum event fluence and peak flux for both solar maximum and solar minimum periods. A new method for describing maximum event fluence and peak flux outputs in terms of 1-in-x-year SPEs is also described. SAPPHIRE proton model outputs are compared with previous models including CREME96, ESP-PSYCHIC and the JPL model. Low energy outputs are compared to SEP data from ACE/EPAM whilst high energy outputs are compared to a new model based on GLEs detected by Neutron Monitors (NMs).

Temperature and pressure influence on maximum rates of pressure rise during explosions of propane-air mixtures in a spherical vessel.

PubMed

Razus, D; Brinzea, V; Mitu, M; Movileanu, C; Oancea, D

2011-06-15

The maximum rates of pressure rise during closed vessel explosions of propane-air mixtures are reported, for systems with various initial concentrations, pressures and temperatures ([C(3)H(8)]=2.50-6.20 vol.%, p(0)=0.3-1.3 bar; T(0)=298-423 K). Experiments were performed in a spherical vessel (Φ=10 cm) with central ignition. The deflagration (severity) index K(G), calculated from experimental values of maximum rates of pressure rise is examined against the adiabatic deflagration index, K(G, ad), computed from normal burning velocities and peak explosion pressures. At constant temperature and fuel/oxygen ratio, both the maximum rates of pressure rise and the deflagration indices are linear functions of total initial pressure, as reported for other fuel-air mixtures. At constant initial pressure and composition, the maximum rates of pressure rise and deflagration indices are slightly influenced by the initial temperature; some influence of the initial temperature on maximum rates of pressure rise is observed only for propane-air mixtures far from stoichiometric composition. The differentiated temperature influence on the normal burning velocities and the peak explosion pressures might explain this behaviour. Copyright © 2011 Elsevier B.V. All rights reserved.

Resonant tube for measurement of sound absorption in gases at low frequency/pressure ratios

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J.; Griffin, W. A.

1980-01-01

The paper describes a resonant tube for measuring sound absorption in gases, with specific emphasis on the vibrational relaxation peak of N2, over a range of frequency/pressure ratios from 0.1 to 2500 Hz/atm. The experimental background losses measured in argon agree with the theoretical wall losses except at few isolated frequencies. Rigid cavity terminations, external excitation, and a differential technique of background evaluation were used to minimize spurious contributions to the background losses. Room temperature measurements of sound absorption in binary mixtures of N2-CO2 in which both components are excitable resulted in the maximum frequency/pressure ratio in Hz/atm of 0.063 + 123m for the N2 vibrational relaxation peak, where m is mole percent of added CO2; the maximum ratio for the CO2 peak was 34,500 268m where m is mole percent of added N2.

Conductive graphene as passive saturable absorber with high instantaneous peak power and pulse energy in Q-switched regime

NASA Astrophysics Data System (ADS)

Zuikafly, Siti Nur Fatin; Khalifa, Ali; Ahmad, Fauzan; Shafie, Suhaidi; Harun, SulaimanWadi

2018-06-01

The Q-switched pulse regime is demonstrated by integrating conductive graphene as passive saturable absorber producing relatively high instantaneous peak power and pulse energy. The fabricated conductive graphene is investigated using Raman spectroscopy. The single wavelength Q-switching operates at 1558.28 nm at maximum input pump power of 151.47 mW. As the pump power is increased from threshold power of 51.6 mW to 151.47 mW, the pulse train repetition rate increases proportionally from 47.94 kHz to 67.8 kHz while the pulse width is reduced from 9.58 μs to 6.02 μs. The generated stable pulse produced maximum peak power and pulse energy of 32 mW and 206 nJ, respectively. The first beat node of the measured signal-to-noise ratio is about 62 dB indicating high pulse stability.

Sensitivity of Heterointerfaces on Emission Wavelength in Quantum Cascade Lasers

DTIC Science & Technology

2016-08-18

sharp satellite peaks and highly resolved thickness interference fringes. The full-width at 4 half-maximum of the n=0 peak is nominally similar... Watanabe , M. Sugiyama, and Y. Nakano, "Effect of hetero-interfaces on in situ wafer curvature behavior in InGaAs/GaAsP strain-balanced MQWs

Fourier transform spectrometer observations of solar carbon monoxide. III - Time-resolved spectroscopy of the Delta V = 1 bands

NASA Astrophysics Data System (ADS)

Ayres, Thomas R.; Brault, James W.

1990-11-01

Time series of the 2100/cm Delta v = 1 absorption bands of CO at the center of the solar disk and at the extreme limb have been recorded by Fourier transform spectrometer. The photospheric 5-min oscillation appears prominently at sun center. The peak-to-peak brightness temperature amplitude is roughly 300 K, and the peak-to-peak Doppler shift is roughly 1100 m/s. The 70 deg phase lag of maximum core intensity with respect to maximum redshift for the strongest Delta v = 1 absorptions is less than the 90 deg expected in the adiabatic limit. No dominant four-minute signal in the line intensity like that reported by Deming et al. (1984, 1986, and 1987) is found, nor is evidence for extreme fluctuations on short time scales like those proposed by Kalkofen et al. (1984). The strong Delta v = 1 lines exhibit systematic Doppler shifts of less than about 1 km/s, contrary to the predictions of transonic redshifts if the CO 'clouds' are associated with a dynamic cooling phase of the Ca II 'cell flashes.'

Crystal growth, structural, low temperature thermoluminescence and mechanical properties of cubic fluoroperovskite single crystal (LiBaF3)

NASA Astrophysics Data System (ADS)

Daniel, D. Joseph; Ramasamy, P.; Ramaseshan, R.; Kim, H. J.; Kim, Sunghwan; Bhagavannarayana, G.; Cheon, Jong-Kyu

2017-10-01

Polycrystalline compounds of LiBaF3 were synthesized using conventional solid state reaction route and the phase purity was confirmed using powder X-ray diffraction technique. Using vertical Bridgman technique single crystal was grown from melt. Rocking curve measurements have been carried out to study the structural perfection of the grown crystal. The single peak of diffraction curve clearly reveals that the grown crystal was free from the structural grain boundaries. The low temperature thermoluminescence of the X-ray irradiated sample has been analyzed and found four distinguishable peaks having maximum temperatures at 18, 115, 133 and 216 K. Activation energy (E) and frequency factor (s) for the individual peaks have been studied using Peak shape method and the computerized curve fitting method combining with the Tmax- TStop procedure. Nanoindentation technique was employed to study the mechanical behaviour of the crystal. The indentation modulus and Vickers hardness of the grown crystal have values of 135.15 GPa and 680.81 respectively, under the maximum indentation load of 10 mN.

Voltage-clamp analysis of membrane currents and excitation-contraction coupling in a crustacean muscle.

PubMed

Weiss, T; Erxleben, C; Rathmayer, W

2001-01-01

A single fibre preparation from the extensor muscle of a marine isopod crustacean is described which allows the analysis of membrane currents and simultaneously recorded contractions under two-electrode voltage-clamp conditions. We show that there are three main depolarisation-gated currents, two are outward and carried by K+, the third is an inward Ca2+ current, I(Ca). Normally, the K+ currents which can be isolated by using K+ channel blockers, mask I(Ca). I(Ca) activates at potentials more positive than -40 mV, is maximal around 0 mV, and shows strong inactivation at higher depolarisation. Inactivation depends on current rather than voltage. Ba2+, Sr2+ and Mg2+ can substitute for Ca2+. Ba2+ currents are about 80% larger than Ca2+ currents and inactivate little. The properties of I(Ca) characterise it as a high threshold L-type current. The outward current consists primarily of a fast, transient A current, I(K(A)) and a maintained, delayed rectifier current, I(K(V)). In some fibres, a small Ca2+-dependent K+ current is also present. I(K(A)) activates fast at depolarisation above -45 mV, shows pronounced inactivation and is almost completely inactivated at holding potentials more positive than -40 mV. I(K(A)) is half-maximally blocked by 70 microM 4-aminopyridine (4-AP), and 70 mM tetraethylammonium (TEA). I(K(V)) activates more slowly, at about -30 mV, and shows no inactivation. It is half-maximally blocked by 2 mM TEA but rather insensitive to 4-AP. Physiologically, the two K+ currents prevent all-or-nothing action potentials and determine the graded amplitude of active electrical responses and associated contractions. Tension development depends on and is correlated with depolarisation-induced Ca2+ influx mediated by I(Ca). The voltage dependence of peak tension corresponds directly to the voltage dependence of the integrated I(Ca). The threshold potential for contraction is at about -38 mV. Peak tension increases with increasing voltage steps, reaches maximum at around 0 mV, and declines with further depolarisation.

Ring Current Dynamics in Moderate and Strong Storms: Comparative Analysis of TWINS and IMAGE/HENA Data with the Comprehensive Ring Current Model

NASA Technical Reports Server (NTRS)

Buzulukova, N.; Fok, M.-C.; Goldstein, J.; Valek, P.; McComas, D. J.; Brandt, P. C.

2010-01-01

We present a comparative study of ring current dynamics during strong and moderate storms. The ring current during the strong storm is studied with IMAGE/HENA data near the solar cycle maximum in 2000. The ring current during the moderate storm is studied using energetic neutral atom (ENA) data from the Two Wide-Angle Imaging Neutral- Atom Spectrometers (TWINS) mission during the solar minimum in 2008. For both storms, the local time distributions of ENA emissions show signatures of postmidnight enhancement (PME) during the main phases. To model the ring current and ENA emissions, we use the Comprehensive Ring Current Model (CRCM). CRCM results show that the main-phase ring current pressure peaks in the premidnight-dusk sector, while the most intense CRCM-simulated ENA emissions show PME signatures. We analyze two factors to explain this difference: the dependence of charge-exchange cross section on energy and pitch angle distributions of ring current. We find that the IMF By effect (twisting of the convection pattern due to By) is not needed to form the PME. Additionally, the PME is more pronounced for the strong storm, although relative shielding and hence electric field skewing is well developed for both events.

Water- and humidity-enhanced UV detector by using p-type La-doped ZnO nanowires on flexible polyimide substrate.

PubMed

Hsu, Cheng-Liang; Li, Hsieh-Heng; Hsueh, Ting-Jen

2013-11-13

High-density La-doped ZnO nanowires (NWs) were grown hydrothermally on flexible polyimide substrate. The length and diameter of the NWs were around 860 nm and 80-160 nm, respectively. All XRD peaks of the La-doped sample shift to a larger angle. The strong PL peak of the La-doped sample is 380 nm, which is close to the 3.3 eV ZnO bandgap. That PL dominated indicates that the La-doped sample has a great amount of oxygen vacancies. The lattice constants ~0.514 nm of the ZnO:La NW were smaller when measured by HR-TEM. The EDX spectrum determined that the La-doped sample contains approximately 1.27 at % La. The La-doped sample was found to be p-type by Hall Effect measurement. The dark current of the p-ZnO:La NWs decreased with increased relative humidity (RH), while the photocurrent of the p-ZnO:La nanowires increased with increased RH. The higher RH environment was improved that UV response performance. Based on the highest 98% RH, the photocurrent/dark current ratio was around 47.73. The UV response of water drops on the p-ZnO:La NWs was around 2 orders compared to 40% RH. In a water environment, the photocurrent/dark current ratio of p-ZnO:La NWs was 212.1, which is the maximum UV response.

Preparation of Al-Si Master Alloy by Electrochemical Reduction of Fly Ash in Molten Salt

NASA Astrophysics Data System (ADS)

Liu, Aimin; Li, Liangxing; Xu, Junli; Shi, Zhongning; Hu, Xianwei; Gao, Bingliang; Wang, Zhaowen; Yu, Jiangyu; Chen, Gong

2014-05-01

An electrochemical method on preparation of Al-Si master alloy was investigated in fluoride-based molten salts of 47.7wt.%NaF-43.3wt.%AlF3-4wt.%CaF2 containing 5 wt.% fly ash at 1233 K. The cathodic products obtained by galvanostatic electrolysis were analyzed by means of x-ray diffraction, x-ray fluorescence, scanning electron microscopy, and energy-dispersive spectrometry. The result showed that the compositions of the products are Al, Si, and Al3.21Si0.47. Meanwhile, the cathodic electrochemical process was studied by cyclic voltammetry, and the results showed the reduction peak of aluminum deposition is at -1.3 V versus the platinum quasi-reference electrode in 50.3wt.%NaF-45.7wt.%AlF3-4wt.%CaF2 molten salts, while the reduction peak at -1.3 V was the co-deposition of aluminum and silicon when the fly ash was added. The silicon and iron were formed via both co-deposition and aluminothermic reduction. In the electrolysis experiments, current efficiency first increased to a maximum value of 40.7% at a current density of 0.29 A/cm2, and then it decreased with the increase of current density. With the electrolysis time lasting, the content of aluminum in the alloys decreased from 76.05 wt.% to 48.29 wt.% during 5 h, while the content of silicon increased from 15.94 wt.% to 37.89 wt.%.

Molecular transistors based on BDT-type molecular bridges.

PubMed

Wheeler, W D; Dahnovsky, Yu

2008-10-21

In this work we study the effect of electron correlations in molecular transistors with molecular bridges based on 1,4-benzene-dithiol (BDT) and 2-nitro-1,4-benzene-dithiol (nitro-BDT) by using ab initio electron propagator calculations. We find that there is no gate field effect for the BDT based transistor in accordance with the experimental data. After verifying the computational method on the BDT molecule, we consider a transistor with a nitro-BDT molecular bridge. From the electron propagator calculations, we predict strong negative differential resistance at small positive and negative values of source-drain voltages. The explanation of the peak and the minimum in the current is given in terms of the molecular orbital picture and switch-on (-off) properties due to the voltage dependencies of the Dyson poles (ionization potentials). When the current is off, the electronic states on both electrodes are populated resulting in the vanishing tunneling probability due to the Pauli principle. Besides the minimum and the maximum in the I-V characteristics, we find a strong gate field effect in the conductance where the peak at V(sd) = 0.15 eV and E(g) = 4x10(-3) a.u. switches to the minimum at E(g) = -4x10(-3) a.u. A similar behavior is discovered at the negative V(sd). Such a feature can be used for fast current modulation by changing the polarity of a gate field.

Correlation peak analysis applied to a sequence of images using two different filters for eye tracking model

NASA Astrophysics Data System (ADS)

Patrón, Verónica A.; Álvarez Borrego, Josué; Coronel Beltrán, Ángel

2015-09-01

Eye tracking has many useful applications that range from biometrics to face recognition and human-computer interaction. The analysis of the characteristics of the eyes has become one of the methods to accomplish the location of the eyes and the tracking of the point of gaze. Characteristics such as the contrast between the iris and the sclera, the shape, and distribution of colors and dark/light zones in the area are the starting point for these analyses. In this work, the focus will be on the contrast between the iris and the sclera, performing a correlation in the frequency domain. The images are acquired with an ordinary camera, which with were taken images of thirty-one volunteers. The reference image is an image of the subjects looking to a point in front of them at 0° angle. Then sequences of images are taken with the subject looking at different angles. These images are processed in MATLAB, obtaining the maximum correlation peak for each image, using two different filters. Each filter were analyzed and then one was selected, which is the filter that gives the best performance in terms of the utility of the data, which is displayed in graphs that shows the decay of the correlation peak as the eye moves progressively at different angle. This data will be used to obtain a mathematical model or function that establishes a relationship between the angle of vision (AOV) and the maximum correlation peak (MCP). This model will be tested using different input images from other subject not contained in the initial database, being able to predict angle of vision using the maximum correlation peak data.

Carpooling: status and potential

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

Kendall, D.C.

1975-06-01

Studies were conducted to analyze the status and potential of work-trip carpooling as a means of achieving more efficient use of the automobile. Current and estimated maximum potential levels of carpooling are presented together with analyses revealing characteristics of carpool trips, incentives, impacts of increased carpooling and issues related to carpool matching services. National survey results indicate the average auto occupancy for urban work-trip is 1.2 passengers per auto. This value, and average carpool occupancy of 2.5, have been relatively stable over the last five years. An increase in work-trip occupancy from 1.2 to 1.8 would require a 100% increasemore » in the number of carpoolers. A model was developed to predict the maximum potential level of carpooling in an urban area. Results from applying the model to the Boston region were extrapolated to estimate a maximum nationwide potential between 47 and 71% of peak period auto commuters. Maximum benefits of increased carpooling include up to 10% savings in auto fuel consumption. A technique was developed for estimating the number of participants required in a carpool matching service to achieve a chosen level of matching among respondents, providing insight into tradeoffs between employer and regional or centralized matching services. Issues recommended for future study include incentive policies and their impacts on other modes, and the evaluation of new and ongoing carpool matching services. (11 references) (GRA)« less

Site-specific Seismic Hazard Assessment to Establish Elastic Design Properties for Oman Museum-Across Ages, Manah, Sultante of Oman

NASA Astrophysics Data System (ADS)

El Hussain, I. W.

2017-12-01

The current study provides a site specific deterministic seismic hazard assessment (DSHA) at the selected site for establishing the Oman Museum-Across Ages at Manah area, as a part of a comprehensive geotechnical and seismological plan to design the facilities accordingly. The DSHA first defines the seismic sources that might influence the site and assesses the maximum possible earthquake magnitude for each of them. By assuming each of these maximum earthquakes to occur at a location placing them at the closest distances to the site, the ground motion is predicted utilizing empirical ground motion prediction equations. The local site effects are performed by determining the fundamental frequency of the soft soil using HVSR technique and by estimating amplification spectra using the soil characteristics (mainly shear-wave velocity). Shear-wave velocity has been evaluated using the MASW technique. The maximum amplification value of 2.1 at spectral period 0.06 sec is observed at the ground surface, while the largest amplification value at the top of the conglomerate layer (at 5m depth) is 1.6 for a spectral period of 0.04 Sec. The maximum median 5% damped peak ground acceleration is found to be 0.263g at a spectral period of 0.1 sec. Keywords: DSHA; Site Effects; HVSR; MASW; PGA; Spectral Period

Drain current enhancement induced by hole injection from gate of 600-V-class normally off gate injection transistor under high temperature conditions up to 200 °C

NASA Astrophysics Data System (ADS)

Ishii, Hajime; Ueno, Hiroaki; Ueda, Tetsuzo; Endoh, Tetsuo

2018-06-01

In this paper, the current–voltage (I–V) characteristics of a 600-V-class normally off GaN gate injection transistor (GIT) from 25 to 200 °C are analyzed, and it is revealed that the drain current of the GIT increases during high-temperature operation. It is found that the maximum drain current (I dmax) of the GIT is 86% higher than that of a conventional 600-V-class normally off GaN metal insulator semiconductor hetero-FET (MIS-HFET) at 150 °C, whereas the GIT obtains 56% I dmax even at 200 °C. Moreover, the mechanism of the drain current increase of the GIT is clarified by examining the relationship between the temperature dependence of the I–V characteristics of the GIT and the gate hole injection effect determined from the shift of the second transconductance (g m) peak of the g m–V g characteristic. From the above, the GIT is a promising device with enough drivability for future power switching applications even under high-temperature conditions.

Velocity and bottom-stress measurements in the bottom boundary layer, outer Norton Sound, Alaska.

USGS Publications Warehouse

Cacchione, D.A.; Drake, D.E.; Wiberg, P.

1982-01-01

We have used long-term measurements of near-bottom velocities at four heights above the sea floor in Norton Sound, Alaska, to compute hourly values of shear velocity u., roughness and bottom-drag coefficient. Maximum sediment resuspension and transport, predicted for periods when the computed value of u. exceeds a critical level, occur during peak tidal currents associated with spring tides. The fortnightly variation in u. is correlated with a distinct nepheloid layer that intensifies and thickens during spring tides and diminishes and thins during neap tides. The passage of a storm near the end of the experiment caused significantly higher u. values than those found during fair weather.-from Authros

High-frequency resonant-tunneling oscillators

NASA Technical Reports Server (NTRS)

Brown, E. R.; Parker, C. D.; Calawa, A. R.; Manfra, M. J.; Chen, C. L.

1991-01-01

Advances in high-frequency resonant-tunneling-diode (RTD) oscillators are described. Oscillations up to a frequency of 420 GHz have been achieved in the GaAs/AlAs system. Recent results obtained with In0.53Ga0.47As/AlAs and InAs/AlSb RTDs show a greatly increased power density and indicate the potential for fundamental oscillations up to about 1 THz. These results are consistent with a lumped-element equivalent circuit model of the RTD. The model shows that the maximum oscillation frequency of the GaAs/AlAs RTDs is limited primarily by series resistance, and that the power density is limited by low peak-to-valley current ratio.

Resonant tunneling with high peak to valley current ratio in SiO{sub 2}/nc-Si/SiO{sub 2} multi-layers at room temperature

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

Chen, D. Y., E-mail: cdy7659@126.com; Nanjing University of posts and Telecommunications, Nanjing 210046; Sun, Y.

We have investigated carrier transport in SiO{sub 2}/nc-Si/SiO{sub 2} multi-layers by room temperature current-voltage measurements. Resonant tunneling signatures accompanied by current peaks are observed. Carrier transport in the multi-layers were analyzed by plots of ln(I/V{sup 2}) as a function of 1/V and ln(I) as a function of V{sup 1/2}. Results suggest that besides films quality, nc-Si and barrier sub-layer thicknesses are important parameters that restrict carrier transport. When thicknesses are both small, direct tunneling dominates carrier transport, resonant tunneling occurs only at certain voltages and multi-resonant tunneling related current peaks can be observed but with peak to valley current ratiomore » (PVCR) values smaller than 1.5. When barrier thickness is increased, trap-related and even high field related tunneling is excited, causing that multi-current peaks cannot be observed clearly, only one current peak with higher PVCR value of 7.7 can be observed. While if the thickness of nc-Si is large enough, quantum confinement is not so strong, a broad current peak with PVCR value as high as 60 can be measured, which may be due to small energy difference between the splitting energy levels in the quantum dots of nc-Si. Size distribution in a wide range may cause un-controllability of the peak voltages.« less

Quasi-free-standing bilayer epitaxial graphene field-effect transistors on 4H-SiC (0001) substrates

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

Yu, C.; Li, J.; Song, X. B.

2016-01-04

Quasi-free-standing epitaxial graphene grown on wide band gap semiconductor SiC demonstrates high carrier mobility and good material uniformity, which make it promising for graphene-based electronic devices. In this work, quasi-free-standing bilayer epitaxial graphene is prepared and its transistors with gate lengths of 100 nm and 200 nm are fabricated and characterized. The 100 nm gate length graphene transistor shows improved DC and RF performances including a maximum current density I{sub ds} of 4.2 A/mm, and a peak transconductance g{sub m} of 2880 mS/mm. Intrinsic current-gain cutoff frequency f{sub T} of 407 GHz is obtained. The exciting DC and RF performances obtained in the quasi-free-standingmore » bilayer epitaxial graphene transistor show the great application potential of this material system.« less

Numerical Stress Analysis during Cooldown and Compressive Loading in an Imperfect Nb 3Sn Wire

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

d’Hauthuille, Luc; Zhai, Yuhu

In this paper, high field superconductors are critical to the success of next step magnetic fusion confinement devices such as ITER and DEMO. The low-temperature superconducting material that is currently favored for these applications, Nb 3Sn, is susceptible to performance due to its brittleness and high strain-sensitivity. Under extreme loads, an irreversible degradation in the maximum critical current density has been shown to occur and believed to be strongly influenced by two factors: plasticity and cracked filaments. Cracks in filaments are induced when sufficiently high stress concentrations occur in the wire. In this paper, we explore using finite element analysismore » the impact that voids have on the stress distributions and peak stresses under two loading conditions: transverse compressive loading in a 2D model, and a full cool down phase in a 3D model.« less

Electron beam emission from a diamond-amplifier cathode.

PubMed

Chang, Xiangyun; Wu, Qiong; Ben-Zvi, Ilan; Burrill, Andrew; Kewisch, Jorg; Rao, Triveni; Smedley, John; Wang, Erdong; Muller, Erik M; Busby, Richard; Dimitrov, Dimitre

2010-10-15

The diamond amplifier (DA) is a new device for generating high-current, high-brightness electron beams. Our transmission-mode tests show that, with single-crystal, high-purity diamonds, the peak current density is greater than 400  mA/mm², while its average density can be more than 100  mA/mm². The gain of the primary electrons easily exceeds 200, and is independent of their density within the practical range of DA applications. We observed the electron emission. The maximum emission gain measured was 40, and the bunch charge was 50  pC/0.5  mm². There was a 35% probability of the emission of an electron from the hydrogenated surface in our tests. We identified a mechanism of slow charging of the diamond due to thermal ionization of surface states that cancels the applied field within it. We also demonstrated that a hydrogenated diamond is extremely robust.

Orange a-plane InGaN/GaN light-emitting diodes grown on r-plane sapphire substrates.

PubMed

Seo, Yong Gon; Baik, Kwang Hyeon; Song, Hooyoung; Son, Ji-Su; Oh, Kyunghwan; Hwang, Sung-Min

2011-07-04

We report on orange a-plane light-emitting diodes (LEDs) with InGaN single quantum well (SQW) grown on r-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). The peak wavelength and the full-width at half maximum (FWHM) at a drive current of 20mA were 612.2 nm and 72 nm, respectively. The device demonstrated a blue shift in emission wavelength from 614.6 nm at 10 mA to 607.5 nm at 100 mA, representing a net shift of 7.1 nm over a 90 mA range, which is the longest wavelength compared with reported values in nonpolar LEDs. The polarization ratio values obtained from the orange LED varied between 0.36 and 0.44 from 10 to 100mA and a weak dependence of the polarization ratio on the injection current was observed.

Influence of insulating coating on aluminum wire explosions

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

Li, Yang; Wu, Jian, E-mail: jxjawj@gmail.com; State Key Laboratory of Intense Pulse Radiation of Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024

2014-10-15

Single wire explosions are widely used in understanding the early stages of z-pinch experiments. This paper presents a serial of experiments conducted on the pulse power generator with ∼1 kA peak current and ∼10 ns rising time in Xi'an Jiao Tong University. Polyimide coated aluminum wires and uncoated ones were tested under three different voltages to analyze the effect of insulating coating. Experimental results showed that insulating coating can increase the energy deposition 10%∼30% in aluminum wires by delaying the voltage collapse and raising the maximum load resistance. The substantial energy deposition resulted in about 20% faster expansion rates for coated wires.more » Experimental evidence that plasma channel shunts the current from the wire core was observed by streak camera and schlieren graphs. This paper also briefly discussed the influence of nonuniform coating on the morphology of wire expansion.« less

Numerical Stress Analysis during Cooldown and Compressive Loading in an Imperfect Nb 3Sn Wire

DOE PAGES

d’Hauthuille, Luc; Zhai, Yuhu

2017-07-11

In this paper, high field superconductors are critical to the success of next step magnetic fusion confinement devices such as ITER and DEMO. The low-temperature superconducting material that is currently favored for these applications, Nb 3Sn, is susceptible to performance due to its brittleness and high strain-sensitivity. Under extreme loads, an irreversible degradation in the maximum critical current density has been shown to occur and believed to be strongly influenced by two factors: plasticity and cracked filaments. Cracks in filaments are induced when sufficiently high stress concentrations occur in the wire. In this paper, we explore using finite element analysismore » the impact that voids have on the stress distributions and peak stresses under two loading conditions: transverse compressive loading in a 2D model, and a full cool down phase in a 3D model.« less

Investigation of molten pool oscillation during GMAW-P process based on a 3D model

NASA Astrophysics Data System (ADS)

Wang, L. L.; Lu, F. G.; Cui, H. C.; Tang, X. H.

2014-11-01

In order to better reveal the oscillation mechanism of the pulsed gas metal arc welding (GMAW-P) process due to an alternately varied welding current, arc plasma and molten pool oscillation were simulated through a self-consistent three-dimensional model. Based on an experimental analysis of the dynamic variation of the arc plasma and molten pool captured by a high-speed camera, the model was validated by comparison of the measured and predicted results. The calculated results showed that arc pressure was the key factor causing the molten pool to oscillate. The variation in arc size and temperature from peak time to base time resulted in a great difference in the heat input and arc pressure acting on the molten pool. The surface deformation of the molten pool due to the varying degrees of arc pressure induced alternate displacement and backflow in the molten metal. The periodic iteration of deeper and shallower surface deformation, drain and backflow of molten metal caused the molten pool to oscillate at a certain frequency. In this condition, the arc pressure at the peak time is more than six times higher than that at the base time, and the maximum surface depression is 1.4 mm and 0.6 mm, respectively, for peak time and base time.

Direct alcohol fuel cells: toward the power densities of hydrogen-fed proton exchange membrane fuel cells.

PubMed

Chen, Yanxin; Bellini, Marco; Bevilacqua, Manuela; Fornasiero, Paolo; Lavacchi, Alessandro; Miller, Hamish A; Wang, Lianqin; Vizza, Francesco

2015-02-01

A 2 μm thick layer of TiO2 nanotube arrays was prepared on the surface of the Ti fibers of a nonwoven web electrode. After it was doped with Pd nanoparticles (1.5 mgPd  cm(-2) ), this anode was employed in a direct alcohol fuel cell. Peak power densities of 210, 170, and 160 mW cm(-2) at 80 °C were produced if the cell was fed with 10 wt % aqueous solutions of ethanol, ethylene glycol, and glycerol, respectively, in 2 M aqueous KOH. The Pd loading of the anode was increased to 6 mg cm(-2) by combining four single electrodes to produce a maximum peak power density with ethanol at 80 °C of 335 mW cm(-2) . Such high power densities result from a combination of the open 3 D structure of the anode electrode and the high electrochemically active surface area of the Pd catalyst, which promote very fast kinetics for alcohol electro-oxidation. The peak power and current densities obtained with ethanol at 80 °C approach the output of H2 -fed proton exchange membrane fuel cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Roles of Magnetosphere-Ionosphere Coupling on Ring Current development: Comparison of TWINS Measurements and CIMI Simulations for the 7-10 September 2015 Geomagnetic Storm

NASA Astrophysics Data System (ADS)

Edmond, J. A.; Hill, S. C.; Xu, H.; Perez, J. D.; Fok, M. C. H.; Goldstein, J.; McComas, D. J.; Valek, P. W.

2017-12-01

The Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS) mission obtained energetic neutral atom (ENA) images during a 4 day storm on 7-10 September 2015. The storm has two separate SYM/H minima, so we divide the storm into four intervals: first main phase, first recovery phase, second main phase, and second recovery phase. Simulations with the Comprehensive Inner Magnetosphere-Ionosphere Model (CIMI) are compared and contrasted with the TWINS observations. We find good agreement in most aspects of the storm. E. G. (1) the location of the ion pressure peaks are most often in the dusk-midnight sector, (2) the pitch angle distributions at the pressure peaks most often display perpendicular anisotropy, and (3) the energy spectra at the pressure peaks have similar maximum energies. There are, however, some exceptions to these general features. We describe and interpret these notable events. We also have examined particle paths determined from the CIMI model simulations to assist in the interpretation of the notable events.In this poster, we focus upon the features of the CIMI simulations with a self-consistent electric field and with the semi-empirical Weimer electric potential in relationship to the TWINS observations.

Manipulation of Thermally Activated Delayed Fluorescence of Blue Exciplex Emission: Fully Utilizing Exciton Energy for Highly Efficient Organic Light Emitting Diodes with Low Roll-Off.

PubMed

Wang, Zixing; Wang, Hedan; Zhu, Jun; Wu, Peng; Shen, Bowen; Dou, Dehai; Wei, Bin

2017-06-28

The application of exciplex energy has become a unique way to achieve organic light-emitting diodes (OLEDs) with high efficiencies, low turn-on voltage, and low roll-off. Novel δ-carboline derivatives with high triplet energy (T 1 ≈ 2.92 eV) and high glass transition temperature (T g ≈ 153 °C) were employed to manipulate exciplex emissions in this paper. Deep blue (peak at 436 nm) and pure blue (peak at 468 nm) thermally activated delayed fluorescence (TADF) of exciplex OLEDs were demonstrated by utilizing them as emitters with the maximum current efficiency (CE) of 4.64 cd A -1 , power efficiency (PE) of 2.91 lm W -1 , and external quantum efficiency (EQE) of 2.36%. Highly efficient blue phosphorescent OLEDs doped with FIrpic showed a maximum CE of 55.6 cd A -1 , PE of 52.9 lm W -1 , and EQE of 24.6% respectively with very low turn on voltage at 2.7 V. The devices still remain high CE of 46.5 cd A -1 at 100 cd m -2 , 45.4 cd A -1 at 1000 cd m -2 and 42.3 cd A -1 at 5000 cd m -2 with EQE close to 20% indicating low roll-off. Manipulating blue exciplex emissions by chemical structure gives an ideal strategy to fully utilize all exciton energies for lighting of OLEDs.

Snowpack Regimes of the Western United States

NASA Astrophysics Data System (ADS)

Trujillo, E.; Molotch, N. P.

2011-12-01

Snow accumulation and melt patterns play a significant role in the water, energy, carbon and nutrient cycles in the montane environments of the Western United States. Recent studies have illustrated that changes in the snow/rainfall apportionments, and snow accumulation and melt patterns may occur as a consequence of changes in climate in the region. In order to understand how these changes may affect the snow regimes of the region, the current characteristics of the snow accumulation and melt patterns must be identified. Here, we characterize the snow water equivalent (SWE) curve formed by the daily SWE values at over seven hundred snow pillow stations in the Western U.S., focusing on several metrics of the yearly SWE curves and the cross relationships between the different metrics. The metrics include the initial snow accumulation and meltout dates, the peak accumulation and date of peak, the time from initial accumulation to peak, the time from peak to meltout, the accumulation and melt slopes, and the daily rates of accumulation and melt. Three distinct regimes emerge from these results: a maritime, an intermediate (intercontinental), and a continental regime. The maritime regime is characterized by higher maximum snow accumulations reaching 300 cm and shorter accumulation periods of less than 220 days, while on the other hand; the continental regime is characterized by lower maximum accumulations below 200 cm and longer accumulation periods reaching over 260 days. The intercontinental regime lies in between. Several other differences are identified between the metrics of the SWE curve in these regimes. The regions that show the characteristics of the maritime regime include the Cascade Mountains, the Klamath Mountains, and the Sierra Nevada Mountains. The intercontinental regime includes the Northern and Central basins and ranges, the Idaho Batholith, the Northern Rockies and the Blue Mountains. Lastly, the Continental regime includes the Middle and Southern Rockies, and the Wasatch and Uinta Mountains. The consequences of the differences between these snow regimes are discussed in the framework of the implications of possible changes in accumulation and melt patterns as a consequence of changes in climate.

Recognition of maximum flooding events in mixed siliciclastic-carbonate systems: Key to global chronostratigraphic correlation

USGS Publications Warehouse

Mancini, E.A.; Tew, B.H.

1997-01-01

The maximum flooding event within a depositional sequence is an important datum for correlation because it represents a virtually synchronous horizon. This event is typically recognized by a distinctive physical surface and/or a significant change in microfossil assemblages (relative fossil abundance peaks) in siliciclastic deposits from shoreline to continental slope environments in a passive margin setting. Recognition of maximum flooding events in mixed siliciclastic-carbonate sediments is more complicated because the entire section usually represents deposition in continental shelf environments with varying rates of biologic and carbonate productivity versus siliciclastic influx. Hence, this event cannot be consistently identified simply by relative fossil abundance peaks. Factors such as siliciclastic input, carbonate productivity, sediment accumulation rates, and paleoenvironmental conditions dramatically affect the relative abundances of microfossils. Failure to recognize these complications can lead to a sequence stratigraphic interpretation that substantially overestimates the number of depositional sequences of 1 to 10 m.y. duration.

Radio Frequency Transistors and Circuits Based on CVD MoS2.

PubMed

Sanne, Atresh; Ghosh, Rudresh; Rai, Amritesh; Yogeesh, Maruthi Nagavalli; Shin, Seung Heon; Sharma, Ankit; Jarvis, Karalee; Mathew, Leo; Rao, Rajesh; Akinwande, Deji; Banerjee, Sanjay

2015-08-12

We report on the gigahertz radio frequency (RF) performance of chemical vapor deposited (CVD) monolayer MoS2 field-effect transistors (FETs). Initial DC characterizations of fabricated MoS2 FETs yielded current densities exceeding 200 μA/μm and maximum transconductance of 38 μS/μm. A contact resistance corrected low-field mobility of 55 cm(2)/(V s) was achieved. Radio frequency FETs were fabricated in the ground-signal-ground (GSG) layout, and standard de-embedding techniques were applied. Operating at the peak transconductance, we obtain short-circuit current-gain intrinsic cutoff frequency, fT, of 6.7 GHz and maximum intrinsic oscillation frequency, fmax, of 5.3 GHz for a device with a gate length of 250 nm. The MoS2 device afforded an extrinsic voltage gain Av of 6 dB at 100 MHz with voltage amplification until 3 GHz. With the as-measured frequency performance of CVD MoS2, we provide the first demonstration of a common-source (CS) amplifier with voltage gain of 14 dB and an active frequency mixer with conversion gain of -15 dB. Our results of gigahertz frequency performance as well as analog circuit operation show that large area CVD MoS2 may be suitable for industrial-scale electronic applications.

Giant Peak Voltage of Thermopower Waves Driven by the Chemical Potential Gradient of Single-Crystalline Bi2 Te3.

PubMed

Singh, Swati; Mun, Hyeona; Lee, Sanghoon; Kim, Sung Wng; Baik, Seunghyun

2017-09-01

The self-propagating exothermic chemical reaction with transient thermovoltage, known as the thermopower wave, has received considerable attention recently. A greater peak voltage and specific power are still demanded, and materials with greater Seebeck coefficients have been previously investigated. However, this study employs an alternative mechanism of transient chemical potential gradient providing an unprecedentedly high peak voltage (maximum: 8 V; average: 2.3 V) and volume-specific power (maximum: 0.11 W mm -3 ; average: 0.04 W mm -3 ) using n-type single-crystalline Bi 2 Te 3 substrates. A mixture of nitrocellulose and sodium azide is used as a fuel, and ultraviolet photoelectron spectroscopy reveals a significant downshift in Fermi energy (≈5.09 eV) of the substrate by p-doping of the fuel. The induced electrical potential by thermopower waves has two distinct sources: the Seebeck effect and the transient chemical potential gradient. Surprisingly, the Seebeck effect contribution is less than 2.5% (≈201 mV) of the maximum peak voltage. The right combination of substrate, fuel doping, and anisotropic substrate geometry results in an order of magnitude greater transient chemical potential gradient (≈5.09 eV) upon rapid removal of fuel by exothermic chemical reaction propagation. The role of fuel doping and chemical potential gradient can be viewed as a key mechanism for enhanced heat to electric conversion performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Intracranial stimulation of the trigeminal nerve in man. III. Sensory potentials.

PubMed Central

Cruccu, G; Inghilleri, M; Manfredi, M; Meglio, M

1987-01-01

Percutaneous electrical stimulation of the trigeminal root was performed in 18 subjects undergoing surgery for idiopathic trigeminal neuralgia or implantation of electrodes into Meckel's cave for recording of limbic epileptic activity. All subjects had normal trigeminal reflexes and evoked potentials. Sensory action potentials were recorded antidromically from the supraorbital (V1), infraorbital (V2) and mental (V3) nerves. In the awake subject, sensory potentials were usually followed by myogenic artifacts due to direct activation of masticatory muscles or reflex activation of facial muscles. In the anaesthetised and curarised subject, sensory potentials from the three nerves showed 1.4-2.2 ms onset latency, 1.9-2.7 ms peak latency and 17-29 microV amplitude. Sensory conduction velocity was computed at the onset latency (maximum CV) and at the peak latency (peak CV). On average, maximum and peak CV were 52 and 39 m/s for V1, 54 and 42 m/s for V2 and 54 and 44 m/s for V3. There was no apparent difference in CV between subjects with trigeminal neuralgia and those with epilepsy. A significant inverse correlation was found between CV and age, the overall maximum CV declining from 59 m/s (16 years) to 49 m/s (73 years). This range of CV is compatible both with histometric data and previous electrophysiological findings on trigeminal nerve conduction. Intraoperative intracranial stimulation is also proposed as a method of monitoring trigeminal function under general anaesthesia. Images PMID:3681311

Electromagnetic pulse-induced current measurement device

NASA Astrophysics Data System (ADS)

Gandhi, Om P.; Chen, Jin Y.

1991-08-01

To develop safety guidelines for exposure to high fields associated with an electromagnetic pulse (EMP), it is necessary to devise techniques that would measure the peak current induced in the human body. The main focus of this project was to design, fabricate, and test a portable, self-contained stand-on device that would measure and hold the peak current and the integrated change Q. The design specifications of the EMP-Induced Current Measurement Device are as follows: rise time of the current pulse, 5 ns; peak current, 20-600 A; charge Q, 0-20 microcoulombs. The device uses a stand-on parallel-plate bilayer sensor and fast high-frequency circuit that are well-shielded against spurious responses to high incident fields. Since the polarity of the incident peak electric field of the EMP may be either positive or negative, the induced peak current can also be positive or negative. Therefore, the device is designed to respond to either of these polarities and measure and hold both the peak current and the integrated charge which are simultaneously displayed on two separate 3-1/2 digit displays. The prototype device has been preliminarily tested with the EMP's generated at the Air Force Weapons Laboratory (ALECS facility) at Kirtland AFB, New Mexico.

Optical monitoring of ion beam Y-Ba-Cu-O sputtering

NASA Astrophysics Data System (ADS)

Klein, J. D.; Yen, A.

1990-11-01

The emission spectra resulting from ion beam sputtering a Y-Ba-Cu-O target were observed as a function of beam voltage and beam current. The spectra were relatively clean with several peaks readily attributed to each of Y, Ba, and Ar. Monitoring of copper and oxygen was more difficult with a single CuO peak and one O peak evident. The intensities of the cation peaks were linear with respect to beam voltage above 400 V. Since target current was found not to be directly proportional to beam current, target power was defined as the product of beam voltage and target current. The response of cation peak height to changes in target power was linear and similar for variations of either beam voltage or target current.

Relation between Peak Power Output in Sprint Cycling and Maximum Voluntary Isometric Torque Production.

PubMed

Kordi, Mehdi; Goodall, Stuart; Barratt, Paul; Rowley, Nicola; Leeder, Jonathan; Howatson, Glyn

2017-08-01

From a cycling paradigm, little has been done to understand the relationships between maximal isometric strength of different single joint lower body muscle groups and their relation with, and ability to predict PPO and how they compare to an isometric cycling specific task. The aim of this study was to establish relationships between maximal voluntary torque production from isometric single-joint and cycling specific tasks and assess their ability to predict PPO. Twenty male trained cyclists participated in this study. Peak torque was measured by performing maximum voluntary contractions (MVC) of knee extensors, knee flexors, dorsi flexors and hip extensors whilst instrumented cranks measured isometric peak torque from MVC when participants were in their cycling specific position (ISOCYC). A stepwise regression showed that peak torque of the knee extensors was the only significant predictor of PPO when using SJD and accounted for 47% of the variance. However, when compared to ISOCYC, the only significant predictor of PPO was ISOCYC, which accounted for 77% of the variance. This suggests that peak torque of the knee extensors was the best single-joint predictor of PPO in sprint cycling. Furthermore, a stronger prediction can be made from a task specific isometric task. Copyright © 2017 Elsevier Ltd. All rights reserved.

Surface morphology and electrical properties of Au/Ni/ Left-Pointing-Angle-Bracket C Right-Pointing-Angle-Bracket /n-Ga{sub 2}O{sub 3}/p-GaSe Left-Pointing-Angle-Bracket KNO{sub 3} Right-Pointing-Angle-Bracket hybrid structures fabricated on the basis of a layered semiconductor with nanoscale ferroelectric inclusions

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

Bakhtinov, A. P., E-mail: chimsp@ukrpost.ua; Vodopyanov, V. N.; Netyaga, V. V.

2012-03-15

Features of the formation of Au/Ni/ Left-Pointing-Angle-Bracket C Right-Pointing-Angle-Bracket /n-Ga{sub 2}O{sub 3} hybrid nanostructures on a Van der Waals surface (0001) of 'layered semiconductor-ferroelectric' composite nanostructures (p-GaSe Left-Pointing-Angle-Bracket KNO{sub 3} Right-Pointing-Angle-Bracket ) are studied using atomic-force microscopy. The room-temperature current-voltage characteristics and the dependence of the impedance spectrum of hybrid structures on a bias voltage are studied. The current-voltage characteristic includes a resonance peak and a portion with negative differential resistance. The current attains a maximum at a certain bias voltage, when electric polarization switching in nanoscale three-dimensional inclusions in the layered GaSe matrix occurs. In the high-frequency region (fmore » > 10{sup 6} Hz), inductive-type impedance (a large negative capacitance of structures, {approx}10{sup 6} F/mm{sup 2}) is detected. This effect is due to spinpolarized electron transport in a series of interconnected semiconductor composite nanostructures with multiple p-GaSe Left-Pointing-Angle-Bracket KNO{sub 3} Right-Pointing-Angle-Bracket quantum wells and a forward-biased 'ferromagnetic metal-semiconductor' polarizer (Au/Ni/ Left-Pointing-Angle-Bracket C Right-Pointing-Angle-Bracket /n{sup +}-Ga{sub 2}O{sub 3}/n-Ga{sub 2}O{sub 3}). A shift of the maximum (current hysteresis) is detected in the current-voltage characteristics for various directions of the variations in bias voltage.« less

Associations of Leisure-Time and Occupational Physical Activity and Cardiorespiratory Fitness With Incident and Recurrent Major Depressive Disorder, Depressive Symptoms, and Incident Anxiety in a General Population.

PubMed

Baumeister, Sebastian E; Leitzmann, Michael F; Bahls, Martin; Dörr, Marcus; Schmid, Daniela; Schomerus, Georg; Appel, Katja; Markus, Marcello R P; Völzke, Henry; Gläser, Sven; Grabe, Hans-Jörgen

2017-01-01

Physical activity and cardiorespiratory fitness may help prevent depression and anxiety. Previous studies have been limited by error-prone measurements. We examined whether self-reported physical activity domains and peak exercise capacity (peakVO₂) are associated with incident and recurrent major depressive disorder (MDD), depressive symptoms, and anxiety disorders. This was a prospective population-based study of 1,080 adult men and women (25-83 years) with a median follow-up of 4.5 years and measures of physical activity during leisure time, sports, and work (Baecke questionnaire); a measure of depressive symptoms (Beck Depression Inventory II); symptom-limited cycle ergometer testing (peakVO₂, oxygen uptake at anaerobic threshold [VO₂@AT], maximum power output at peak exertion); and a structured psychiatric interview (Munich Composite International Diagnostic Interview). Baseline data were collected between 2002 and 2006, and follow-up data, between 2007 and 2010. After adjustment for age, sex, education, smoking, alcohol consumption, and waist circumference, the relative risks for incident MDD per standard deviation (SD) increase in leisure-time physical activity, physical activity during sport, physical activity at work, peakVO₂, VO₂@AT, and maximum power output were 1.002 (95% confidence interval, 0.90 to 1.12), 1.02 (0.90 to 1.15), 0.94 (0.80 to 1.10), 0.71 (0.52 to 0.98), 0.83 (0.66 to 1.04), and 0.71 (0.52 to 0.96), respectively. PeakVO₂, VO₂@AT, and maximum power output were associated with recurrent MDD, depressive symptoms, and anxiety. PeakVO₂ was more strongly related to the co-occurrence of MDD and anxiety (adjusted odds ratio [OR] = 0.45 [0.24 to 0.84]) than depression or anxiety alone (OR = 0.71 [0.53 to 0.94]). Greater cardiorespiratory fitness but not domain-specific physical activity was associated with a lower incidence of MDD and clinical anxiety. © Copyright 2017 Physicians Postgraduate Press, Inc.

The visual framing of graphics when used in preventative health digital news packages: exploring the use of a narrative structure as the message infrastructure.

PubMed

Sontag, Jennah M; Barnes, Spencer R

2017-09-26

Visual framing can improve health-message effectiveness. Narrative structure provides a template needed for determining how to frame visuals to maximise message effectiveness. Participants (N = 190) were assigned to a message condition determined by segments (establisher, initial, peak), graphic (static, animated) and cancer (lung, melanoma). ANOVAs revealed that melanoma was more believable than lung cancer with static graphics at the establisher and peak; narratives were more believable with animated graphics at the peak segment; melanoma elicited greater positive attitudes; graphics in the peak influenced greatest intentions. Animated graphics visually framed to emphasise information at the establisher and peak segments suggest maximum effectiveness.

In-shoe plantar tri-axial stress profiles during maximum-effort cutting maneuvers.

PubMed

Cong, Yan; Lam, Wing Kai; Cheung, Jason Tak-Man; Zhang, Ming

2014-12-18

Soft tissue injuries, such as anterior cruciate ligament rupture, ankle sprain and foot skin problems, frequently occur during cutting maneuvers. These injuries are often regarded as associated with abnormal joint torque and interfacial friction caused by excessive external and in-shoe shear forces. This study simultaneously investigated the dynamic in-shoe localized plantar pressure and shear stress during lateral shuffling and 45° sidestep cutting maneuvers. Tri-axial force transducers were affixed at the first and second metatarsal heads, lateral forefoot, and heel regions in the midsole of a basketball shoe. Seventeen basketball players executed both cutting maneuvers with maximum efforts. Lateral shuffling cutting had a larger mediolateral braking force than 45° sidestep cutting. This large braking force was concentrated at the first metatarsal head, as indicated by its maximum medial shear stress (312.2 ± 157.0 kPa). During propulsion phase, peak shear stress occurred at the second metatarsal head (271.3 ± 124.3 kPa). Compared with lateral shuffling cutting, 45° sidestep cutting produced larger peak propulsion shear stress (463.0 ± 272.6 kPa) but smaller peak braking shear stress (184.8 ± 181.7 kPa), of which both were found at the first metatarsal head. During both cutting maneuvers, maximum medial and posterior shear stress occurred at the first metatarsal head, whereas maximum pressure occurred at the second metatarsal head. The first and second metatarsal heads sustained relatively high pressure and shear stress and were expected to be susceptible to plantar tissue discomfort or injury. Due to different stress distribution, distinct pressure and shear cushioning mechanisms in basketball footwear might be considered over different foot regions. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Formation of Lunar Impact Basins: Observational Constraints from LRO Datasets and Comparisons with Models

NASA Astrophysics Data System (ADS)

Baker, D. M. H.; Head, J. W., III

2016-12-01

Impact basins provide windows into the subsurface and through time on a planetary body. However, meaningful geologic interpretations rely on a detailed understanding of their formation and the origin of basin materials. Data from the Lunar Reconnaissance Orbiter (LRO) have been critical to advancing our understanding of the formation of impact basins. We present a number of recent observations, including measurements of basin morphometry, mineralogy, and gravity anomalies, which provide a framework for constraining current formation models. Image data from the LRO Wide Angle Camera (WAC) and altimetry data from the Lunar Orbiter Laser Altimeter (LOLA) were used to refine the recognition of both fresh and degraded impact basins, including their ring structures. Analyses of gravity anomalies from the GRAIL mission show that mantle uplifts confined within the inner basin rings are characteristics that basins acquire from the onset. We used LOLA data to also make new measurements of basin morphometry. Small basins possessing two concentric rings ("peak-ring basins") have unique topographic signatures, consisting of inner depressions bounded by a peak ring and a higher annulus that grades to steeper wall material. LRO Narrow Angle Camera (NAC) images and Diviner rock abundance maps were used to identify boulder-rich outcrops in basin rings, which focused mineralogical analyses using Moon Mineralogy Mapper hyperspectral data. Crystalline plagioclase and candidate shock plagioclase outcrops were found to be abundant within basins of all sizes. These observations combined with crater scaling laws and lunar crustal thickness constrain the depth of origin of basin peak rings to be near the maximum depth of excavation. Comparisons between iSALE numerical models and observations show important consistencies and inconsistencies that can help to refine current models. In particular, improvements in the match between observed and modeled morphometry of craters transitional between complex craters with central peaks and peak-ring basins are needed. Models of the predicted gravity signature for a range of basin sizes could also benefit from additional comparisons with those observed. This work also provides a framework for understanding the degraded impact-basin record on Earth, including the Chicxulub basin.

THE FAST DECLINING TYPE Ia SUPERNOVA 2003gs, AND EVIDENCE FOR A SIGNIFICANT DISPERSION IN NEAR-INFRARED ABSOLUTE MAGNITUDES OF FAST DECLINERS AT MAXIMUM LIGHT

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

Krisciunas, Kevin; Marion, G. H.; Suntzeff, Nicholas B.

2009-12-15

We obtained optical photometry of SN 2003gs on 49 nights, from 2 to 494 days after T(B {sub max}). We also obtained near-IR photometry on 21 nights. SN 2003gs was the first fast declining Type Ia SN that has been well observed since SN 1999by. While it was subluminous in optical bands compared to more slowly declining Type Ia SNe, it was not subluminous at maximum light in the near-IR bands. There appears to be a bimodal distribution in the near-IR absolute magnitudes of Type Ia SNe at maximum light. Those that peak in the near-IR after T(B {sub max})more » are subluminous in the all bands. Those that peak in the near-IR prior to T(B {sub max}), such as SN 2003gs, have effectively the same near-IR absolute magnitudes at maximum light regardless of the decline rate {delta}m {sub 15}(B). Near-IR spectral evidence suggests that opacities in the outer layers of SN 2003gs are reduced much earlier than for normal Type Ia SNe. That may allow {gamma} rays that power the luminosity to escape more rapidly and accelerate the decline rate. This conclusion is consistent with the photometric behavior of SN 2003gs in the IR, which indicates a faster than normal decline from approximately normal peak brightness.« less

Effect of motor unit recruitment on functional vasodilatation in hamster retractor muscle

PubMed Central

Van Teeffelen, Jurgen W G E; Segal, Steven S

2000-01-01

The effect of motor unit recruitment on functional vasodilatation was investigated in hamster retractor muscle. Recruitment (i.e. peak tension) was controlled with voltage applied to the spinal accessory nerve (high = maximum tension; intermediate = ∼50% maximum; low = ∼25% maximum). Vasodilatory responses (diameter × time integral, DTI) to rhythmic contractions (1 per 2 s for 65 s) were evaluated in first, second and third orderarterioles and in feed arteries. Reciprocal changes in duty cycle (range, 2·5–25 %) effectively maintained the total active tension (tension × time integral, TTI) constant across recruitment levels. With constant TTI and stimulation frequency (40 Hz), DTI in all vessels increased with motor unit recruitment. DTI increased from distal arterioles up through proximal feed arteries. To determine whether the effect of recruitment on DTI was due to increased peak tension, the latter was controlled with stimulation frequency (15, 20 and 40 Hz) during maximum (high) recruitment. With constant TTI, DTI then decreased as peak tension increased. To explore the interaction between recruitment and duty cycle on DTI, each recruitment level was applied at 2.5, 10 and 20 % duty cycle (at 40 Hz). For a given increase in TTI, recruitment had a greater effect on DTI than did duty cycle. Functional vasodilatation in response to rhythmic contractions is facilitated by motor unit recruitment. Thus, vasodilatory responses are determined not only by the total tension produced, but also by the number of active motor units. PMID:10747197

Cooling System to Treat Exercise-Induced Hyperthermia

DTIC Science & Technology

2016-06-01

temperatures . Additionally, individual variations in sweat rates, ventilation rates, fitness levels, and oxygen consumption were not...gastrointestinal MHR maximum heart rate NASA National Aeronautics and Space Administration Tc core temperature UCHS uncompensated heat stress VO2peak peak oxygen consumption ...the effectiveness of a cooling pump based patient thermal management system supplied by Aspen Systems on lowering core body temperature

Silicon-Based Quantum MOS Technology Development

DTIC Science & Technology

2000-03-07

resonant interband tunnel diodes were demonstrated with peak current density greater than 104 A/cm2; peak-to-valley current ratio exceeding 2 was...photon emission reduce the peak-to-valley current ratio and device performance. Therefore, interband tunnel devices should be more resilient to...Comparison of bipolar interband tunnel and optical devices: (a) Esaki diode biased into the valley current region and (b) optical light emitter. The Esaki

Repetitive flash x-ray generator having a high-durability diode driven by a two-cable-type line pulser

NASA Astrophysics Data System (ADS)

Shikoda, A.; Sato, E.; Sagae, M.; Oizumi, T.; Tamakawa, Y.; Yanagisawa, T.

1994-04-01

The fundamental studies of a repetitive soft flash x-ray generator having a high-durability diode for high-speed radiography in biomedical and technological fields are described. This generator consisted of the following essential components: a constant negative high-voltage power supply, a line-type high-voltage pulser with two 10 m coaxial-cable condensers, each with a capacity of 1.0 nF, a thyratron pulser as a trigger device, an oil-diffusion pump, and a flash x-ray tube. The x-ray tube was of a diode type which was evacuated by an oil-diffusion pump with a pressure of approximately 6.7×10-3 Pa and was composed of a planar tungsten anode, a planar ferrite cathode, and a polymethylmethacrylate tube body. The space between the anode and cathode electrodes (AC space) could be regulated from the outside of the tube. The two cable condensers were charged from -40 to -60 kV by a power supply, and the output voltage was about -1.5 times the charged voltage. Both the first peak voltage and current increased according to increases in the charged voltage, and the maximum values of the voltage and current were about 90 kV and 0.72 kA, respectively. The pulse widths had values of less than 100 ns, and the maximum x-ray intensity was approximately 1.1 μC/kg at 0.5 m per pulse. The repetition rate was less than 54 Hz, and the maximum focal spot size was about 2.0×2.5 mm.

Adjusting measured peak discharges from an urbanizing watershed to reflect a stationary land use signal

NASA Astrophysics Data System (ADS)

Beighley, R. Edward; Moglen, Glenn E.

2003-04-01

A procedure to adjust gauged streamflow data from watersheds urbanized during or after their gauging period is presented. The procedure adjusts streamflow to be representative of a fixed land use condition, which may reflect current or future development conditions. Our intent is to determine what an event resulting in a peak discharge in, for example, 1950 (i.e., before urbanization) would produce on the current urban watershed. While past approaches assumed uniform spatial and temporal changes in urbanization, this study focuses on the use of geographic information systems (GIS) based methodologies for precisely locating in space and time where land use change has occurred. This information is incorporated into a hydrologic model to simulate the change in discharge as a result of changing land use conditions. In this paper, we use historical aerial photographs, GIS linked tax-map data, and recent land use/land cover data to recreate the spatial development history of eight gauged watersheds in the Baltimore-Washington, D. C., metropolitan area. Using our procedure to determine discharge series representative of the current urban watersheds, we found that the increase of the adjusted 2-year discharge ranged from 16 to 70 percent compared with the measured annual maximum discharge series. For the 100-year discharge the adjusted values ranged from 0 to 47 percent greater than the measured values. Additionally, relationships between the increase in flood flows and four measures of urbanization (increase in urban land, decrease in forested land, increase in high-density development, and the spatial development pattern) are investigated for predicting the increase in flood flows for ungauged watersheds. Watersheds with the largest increases in flood flows typically had more extensive development in the areas far removed from the outlet. In contrast, watersheds with development located nearer to the outlet typically had the smallest increases in peak discharge.

Heart Rate Dynamics During A Treadmill Cardiopulmonary Exercise Test in Optimized Beta-Blocked Heart Failure Patients

PubMed Central

Carvalho, Vitor Oliveira; Guimarães, Guilherme Veiga; Ciolac, Emmanuel Gomes; Bocchi, Edimar Alcides

2008-01-01

BACKGROUND Calculating the maximum heart rate for age is one method to characterize the maximum effort of an individual. Although this method is commonly used, little is known about heart rate dynamics in optimized beta-blocked heart failure patients. AIM The aim of this study was to evaluate heart rate dynamics (basal, peak and % heart rate increase) in optimized beta-blocked heart failure patients compared to sedentary, normal individuals (controls) during a treadmill cardiopulmonary exercise test. METHODS Twenty-five heart failure patients (49±11 years, 76% male), with an average LVEF of 30±7%, and fourteen controls were included in the study. Patients with atrial fibrillation, a pacemaker or noncardiovascular functional limitations or whose drug therapy was not optimized were excluded. Optimization was considered to be 50 mg/day or more of carvedilol, with a basal heart rate between 50 to 60 bpm that was maintained for 3 months. RESULTS Basal heart rate was lower in heart failure patients (57±3 bpm) compared to controls (89±14 bpm; p<0.0001). Similarly, the peak heart rate (% maximum predicted for age) was lower in HF patients (65.4±11.1%) compared to controls (98.6±2.2; p<0.0001). Maximum respiratory exchange ratio did not differ between the groups (1.2±0.5 for controls and 1.15±1 for heart failure patients; p=0.42). All controls reached the maximum heart rate for their age, while no patients in the heart failure group reached the maximum. Moreover, the % increase of heart rate from rest to peak exercise between heart failure (48±9%) and control (53±8%) was not different (p=0.157). CONCLUSION No patient in the heart failure group reached the maximum heart rate for their age during a treadmill cardiopulmonary exercise test, despite the fact that the percentage increase of heart rate was similar to sedentary normal subjects. A heart rate increase in optimized beta-blocked heart failure patients during cardiopulmonary exercise test over 65% of the maximum age-adjusted value should be considered an effort near the maximum. This information may be useful in rehabilitation programs and ischemic tests, although further studies are required. PMID:18719758

Highly efficient near ultraviolet organic light-emitting diode based on a meta-linked donor–acceptor molecule† †Electronic supplementary information (ESI) available: The details of the synthesis; the ground state and excited state geometries in PPI, TPA–PPI and mTPA–PPI; absorption and emission properties of PPI, TPA–PPI and mTPA–PPI in the gas phase; detailed absorption peak positions, emission peak positions and ηPL values of PPI and mTPA–PPI in different solvents; HOMO and LUMO of mTPA–PPI at ground state; NTO for the S0 → S1 absorption transition in PPI, TPA–PPI and mTPA–PPI; NTO for S0 → Sn electronic transition character in mTPA–PPI; lifetime measurement, radiative transition rates and non-radiative transition rates of PPI and mTPA–PPI in hexane and THF solutions; low-temperature fluorescence and phosphorescence spectra of PPI and mTPA–PPI; CV curves of PPI and mTPA–PPI, and schematic diagram of design principle of mTPA–PPI; TGA and DSC graphs of PPI and mTPA–PPI; current efficiency–current density–power efficiency curves and EL spectra at different driving voltages of PPI and mTPA–PPI devices. See DOI: 10.1039/c5sc01131k

PubMed Central

Liu, Haichao; Bai, Qing; Yao, Liang; Zhang, Haiyan; Xu, Hai; Zhang, Shitong; Li, Weijun; Gao, Yu; Li, Jinyu; Lu, Ping; Wang, Hongyan; Ma, Yuguang

2015-01-01

A novel near ultraviolet (NUV) emitter with a meta-linked donor–acceptor (D–A) structure between triphenylamine (TPA) and phenanthroimidazole (PPI), mTPA–PPI, was designed and synthesized. This molecular design is expected to resolve the conflict between the non-red-shifted emission and the introduction of a charge-transfer (CT) state in the D–A system, aiming at NUV organic light-emitting diodes (OLEDs) with high-efficiency and colour-purity. Theoretical calculations and photophysical experiments were implemented to verify the unique excited state properties of mTPA–PPI. The mTPA–PPI device exhibited excellent NUV electroluminescence (EL) performance with an emission peak at 404 nm, a full width at half maximum (FWHM) of only 47 nm corresponding to a CIE coordinate of (0.161, 0.049), and a maximum external quantum efficiency (EQE) of 3.33%, which is among the best results for NUV OLEDs. This work not only demonstrates the promising potential of mTPA–PPI in NUV OLEDs, but also provides a valuable strategy for the rational design of NUV materials by using the meta-linked D–A architecture. PMID:29218149

Estimations of One Repetition Maximum and Isometric Peak Torque in Knee Extension Based on the Relationship Between Force and Velocity.

PubMed

Sugiura, Yoshito; Hatanaka, Yasuhiko; Arai, Tomoaki; Sakurai, Hiroaki; Kanada, Yoshikiyo

2016-04-01

We aimed to investigate whether a linear regression formula based on the relationship between joint torque and angular velocity measured using a high-speed video camera and image measurement software is effective for estimating 1 repetition maximum (1RM) and isometric peak torque in knee extension. Subjects comprised 20 healthy men (mean ± SD; age, 27.4 ± 4.9 years; height, 170.3 ± 4.4 cm; and body weight, 66.1 ± 10.9 kg). The exercise load ranged from 40% to 150% 1RM. Peak angular velocity (PAV) and peak torque were used to estimate 1RM and isometric peak torque. To elucidate the relationship between force and velocity in knee extension, the relationship between the relative proportion of 1RM (% 1RM) and PAV was examined using simple regression analysis. The concordance rate between the estimated value and actual measurement of 1RM and isometric peak torque was examined using intraclass correlation coefficients (ICCs). Reliability of the regression line of PAV and % 1RM was 0.95. The concordance rate between the actual measurement and estimated value of 1RM resulted in an ICC(2,1) of 0.93 and that of isometric peak torque had an ICC(2,1) of 0.87 and 0.86 for 6 and 3 levels of load, respectively. Our method for estimating 1RM was effective for decreasing the measurement time and reducing patients' burden. Additionally, isometric peak torque can be estimated using 3 levels of load, as we obtained the same results as those reported previously. We plan to expand the range of subjects and examine the generalizability of our results.

Thermal power and heat energy of cloud-to-ground lightning process

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

Wang, Xuejuan; Yuan, Ping; Xue, Simin

2016-07-15

A cloud-to-ground lightning flash with nine return strokes has been recorded using a high speed slitless spectrograph and a system composed of a fast antenna and a slow antenna. Based on the spectral data and the synchronous electric field changes that were caused by the lightning, the electrical conductivity, the channel radii, the resistance per unit length, the peak current, the thermal power at the instant of peak current, and the heat energy per unit length during the first 5 μs in the discharge channel have all been calculated. The results indicate that the channel radii have linear relationships with themore » peak current. The thermal power at the peak current time increases with increasing resistance, but exponential decays with the square of the peak current.« less

Intravenous lipid emulsion alters the hemodynamic response to epinephrine in a rat model.

PubMed

Carreiro, Stephanie; Blum, Jared; Jay, Gregory; Hack, Jason B

2013-09-01

Intravenous lipid emulsion (ILE) is an adjunctive antidote used in selected critically ill poisoned patients. These patients may also require administration of advanced cardiac life support (ACLS) drugs. Limited data is available to describe interactions of ILE with standard ACLS drugs, specifically epinephrine. Twenty rats with intra-arterial and intravenous access were sedated with isoflurane and split into ILE or normal saline (NS) pretreatment groups. All received epinephrine 15 μm/kg intravenously (IV). Continuous mean arterial pressure (MAP) and heart rate (HR) were monitored until both indices returned to baseline. Standardized t tests were used to compare peak MAP, time to peak MAP, maximum change in HR, time to maximum change in HR, and time to return to baseline MAP/HR. There was a significant difference (p = 0.023) in time to peak MAP in the ILE group (54 s, 95 % CI 44-64) versus the NS group (40 s, 95 % CI 32-48) and a significant difference (p = 0.004) in time to return to baseline MAP in ILE group (171 s, 95 % CI 148-194) versus NS group (130 s, 95 % CI 113-147). There were no significant differences in the peak change in MAP, peak change in HR, time to minimum HR, or time to return to baseline HR between groups. ILE-pretreated rats had a significant difference in MAP response to epinephrine; ILE delayed the peak effect and prolonged the duration of effect of epinephrine on MAP, but did not alter the peak increase in MAP or the HR response.

A study of the geomagnetic indices asymmetry based on the interplanetary magnetic field polarities

NASA Astrophysics Data System (ADS)

El-Borie, M. A.; El-Taher, A. M.; Aly, N. E.; Bishara, A. A.

2018-05-01

Data of geomagnetic indices ( aa, Kp, Ap, and Dst) recorded near 1 AU over the period 1967-2016, have been studied based on the asymmetry between the interplanetary magnetic field (IMF) directions above and below of the heliospheric current sheet (HCS). Our results led to the following conclusions: (i) Throughout the considered period, 31 random years (62%) showed apparent asymmetries between Toward (T) and Away (A) polarity days and 19 years (38%) exhibited nearly a symmetrical behavior. The days of A polarity predominated over the T polarity days by 4.3% during the positive magnetic polarity epoch (1991-1999). While the days of T polarity exceeded the days of A polarity by 5.8% during the negative magnetic polarity epoch (2001-2012). (ii) Considerable yearly North-South (N-S) asymmetries of geomagnetic indices observed throughout the considered period. (iii) The largest toward dominant peaks for aa and Ap indices occurred in 1995 near to minimum of solar activity. Moreover, the most substantial away dominant peaks for aa and Ap indices occurred in 2003 (during the descending phase of the solar cycle 23) and in 1991 (near the maximum of solar activity cycle) respectively. (iv) The N-S asymmetry of Kp index indicated a most significant away dominant peak occurred in 2003. (v) Four of the away dominant peaks of Dst index occurred at the maxima of solar activity in the years 1980, 1990, 2000, and 2013. The largest toward dominant peak occurred in 1991 (at the reversal of IMF polarity). (vi) The geomagnetic indices ( aa, Ap, and Kp) all have northern dominance during positive magnetic polarity epoch (1971-1979), while the asymmetries shifts to the southern solar hemisphere during negative magnetic polarity epoch (2001-2012).

The effects of co-administration of benzhexol on the peripheral pharmacokinetics of oral levodopa in young volunteers

PubMed Central

ROBERTS, J.; WALLER, D. G.; RENWICK, A. G.; O'SHEA, N.; MACKLIN, B. S.; BULLING, M.

1996-01-01

1 The effects of benzhexol on the absorption and pharmacokinetics of an oral dose of levodopa have been studied in 10 young healthy volunteers. Subjects were given a suspension of levodopa (250 mg) 90 min after either benzhexol (5 mg) or placebo in a randomized cross over design with doses separated by at least 1 week; on each occasion carbidopa was given 1 h before and 5 h after the dose of levodopa. Soluble paracetamol and radiolabelled DTPA were given with the levodopa as markers of gastric emptying. 2 Most subjects showed two peaks in the levodopa plasma concentration–time curve on the placebo day, with the second minor peak occurring 1–2 h after the dose. After benzhexol administration all subjects showed two or more peak levodopa concentrations in plasma. Benzhexol administration caused a significant decrease in the maximum concentration (43%; P<0.05) of the initial peak and an increase (22%; P<0.1) in the maximum concentration of the second peak. This change in absorption profile caused by benzhexol significantly altered the ratios of the second peak compared with the initial peak for both the maximum concentrations (P<0.02) and for the AUC values (P<0.05). Benzhexol administration did not affect the total AUC of levodopa (7.30±1.09 vs 7.19±1.26 μg ml−1 h; means±s.d.). 3 The plasma concentration–time curves for paracetamol showed similar profiles to those for levodopa and the ratios of the peak concentrations and AUC values for the second peak compared with the initial peak were increased significantly by benzhexol administration (P<0.05). The total AUC of paracetamol was not affected by benzhexol administration (39.4±8.2 vs 40.0±8.9 μg ml−1 h; mean±s.d.) 4 Benzhexol altered the gastric emptying profile, shown by γ-scintigraphy, with a reduced extent of initial emptying prior to the establishment of the plateau which is characteristic of levodopa administration in the fasting state. In consequence the ratio of the second to the initial phase of emptying was significantly higher (P<0.01) following benzhexol treatment. 5 Benzhexol reduces the initial phase of gastric emptying after a dose of levodopa so that there is a decrease in the initial peak and a greater proportion of the dose is absorbed subsequently following the second phase of gastric emptying which occurs approximately 1 h later. Theoretically, this altered concentration-time profile could be an advantage for some patients with Parkinson's disease. PMID:8730980

Large variations in diurnal and seasonal patterns of sap flux among Aleppo pine trees in semi-arid forest reflect tree-scale hydraulic adjustments

NASA Astrophysics Data System (ADS)

Preisler, Yakir; Tatarinov, Fyodor; Rohatyn, Shani; Rotenberg, Eyal; Grünzweig, José M.; Klein, Tamir; Yakir, Dan

2015-04-01

Adjustments and adaptations of trees to drought vary across different biomes, species and habitats, with important implications for tree mortality and forest dieback associated with global climate change. The aim of this study was to investigate possible links between the patterns of variations in water flux dynamics and drought resistance in Aleppo pine (Pinus halepensis) trees in a semi-arid stand (Yatir forest, Israel). We measured sap flow (SF) and variations in stem diameter, complemented with short-term campaigns of leaf-scale measurements of water vapour and CO2 gas exchange, branch water potential and hydraulic conductivity, as well as eddy flux measurements of evapotranspiration (ET) from a permanent flux tower at the site. SF rates were well synchronized with ET, reaching maximum rates during midday in all trees during the rainy season (Dec-Apr). However, during the dry season (May-Nov), the daily trend in the rates of SF greatly varied among trees, allowing classification into three tree classes: 1) trees with SF maximum rate constantly occurring in mid-day (12:00-13:00); 2)trees showing a shift to an early morning SF peak (04:00-06:00); and 3) trees shifting their daily SF peak to the evening (16:00-18:00). This classification did not change during the four years study period, between 2010 and 2014. Checking for correlation of tree parameters as DBH, tree height, crown size, and competition indices with rates of SF, indicated that timing of maximum SF in summer was mainly related to tree size (DBH), when large trees tended to have a later SF maximum. Dendrometer measurements indicated that large trees (high DBH) had maximum daily diameter in the morning during summer and winter, while small trees typically had maximum daily diameter during midday and afternoon in winter and summer, respectively. Leaf-scale transpiration (T) measurements showed typical morning peak in all trees, and another peak in the afternoon in large trees only. Different diurnal curves observed during the dry season, indicated that water potential and hydraulic conductivity values in larger trees restored from midday depression earlier than in smaller ones. The results demonstrate large heterogeneity in the behaviour related to tree water relations among trees of the same species and in the same stand. The combination of diurnal leaf-scale measurements, SF and changes in DBH demonstrated the different strategies of individual trees of different sizes. Large trees with sufficient internal water storage can more freely manipulate their water storage capacity, with reduced dependence on environmental conditions (e.g., morning and afternoon peaks of T). On the other hand, during the dry summer small trees with insufficient internal water storage are strongly restricted by low soil water availability and extreme environmental conditions, which is expressed in only one peak of T, midday to afternoon shift of diurnal DBH maximum, and shift in SF to predawn when soil water potential is highest. Refilling of internal water storage seems to be in the afternoon/evening since T becomes smaller than SF and DBH increases. Reliance on external water availability in small trees might be insufficient during long drought episodes when soil water content decreases below threshold required for extraction by the trees, leading to increased tree mortality in small DBH trees.

Plasma fluctuations in a Kaufman thruster. [root mean square magnitude, spectra and cross correlation

NASA Technical Reports Server (NTRS)

Serafini, J. S.; Terdan, F. F.

1973-01-01

Measurements of the RMS magnitude, spectra and cross-correlations for the fluctuations in the beam, discharge and neutralizer keeper currents are presented for a 30-cm diameter dished grid ion thrustor for a range of magnetic baffle currents and up to 2.0 amperes beam current. The ratio of RMS to mean ion beam current varied from 0.04 to 0.23. The spectra of the amplitudes of the beam and discharge current fluctuations were taken up to 9 MHz and show that the predominant amplitudes occur at frequencies of 10 kHz or below. The fall-off with increasing frequency is rapid. Frequencies above 100 kHz the spectral levels are 45 kb or more below the maximum peak amplitudes. The cross-correlations revealed the ion beam fluctuations to have large radial and axial scales which implied that the beam fluctuates as a whole or 'in-phase.' The cross-correlations of the beam and neutralizer keeper current fluctuations indicated the neutralizer contributions to the beam fluctuations to be small, but not negligible. The mode of operation of the thrustor (values of beam and magnetic baffle currents) was significant in determining the RMS magnitude and spectral shape of the beam fluctuations. The major oscillations were not found to be directly dependent on the power conditioner inverter frequencies.

A high output voltage flexible piezoelectric nanogenerator using porous lead-free KNbO3 nanofibers

NASA Astrophysics Data System (ADS)

Ganeshkumar, Rajasekaran; Cheah, Chin Wei; Xu, Ruize; Kim, Sang-Gook; Zhao, Rong

2017-07-01

Self-powered nanodevices for applications such as sensor networks and IoTs are among the emerging technologies in electronics. Piezoelectric nanogenerators (P-NGs) that harvest energy from mechanical stimuli are highly valuable in the development of self-sufficient nanosystems. Despite progress in the development of P-NGs, the use of porous perovskite ferroelectric nanofibers was barely considered or discussed. In this letter, a flexible high output nanogenerator is fabricated using a nanocomposite comprising porous potassium niobate (KNbO3) nanofibers and polydimethylsiloxane. When a compressive force was applied to as-fabricated P-NG, a peak-to-peak output voltage of ˜16 V and a maximum closed circuit current of 230 nA were obtained, which are high enough to realize self-powered nanodevices. In addition, due to their porosity and non-toxic nature, KNbO3 nanofibers may be used as an alternative to the dominant lead-based piezoelectric devices. Besides the high output performance of the device, multifunctional capability, flexible design, and cost-effective construction of the as-fabricated P-NG can be crucial to large-scale deployment of autonomous devices.

Evaluation of a multiarray system for pharmaceutical analysis by microemulsion electrokinetic chromatography.

PubMed

Lynen, Frederic; Saavedra, Luis; Saveedra, Luis; Nickerson, Beverly; Sandra, Pat

2011-05-15

A multiplexed capillary electrophoresis (CE) system equipped with 96 channels was evaluated for high-throughput screening in drug discovery by microemulsion electrokinetic chromatography (MEEKC). Method transfer from a single channel to a multichannel CE system is described. Loss of efficiency and reduced migration times could be elucidated to the poor efficacy in Joule heat dissipation by forced air cooling in the multiarray system compared to liquid cooling in the single channel instrument. On the other hand, only 48 channels could actually be used because of the maximum total current of 3 mA. Precision data remained below 8% and 9% for migration times and peak areas, respectively. Some UV-detector cross-talk interference between neighboring capillary channels was noted. Impurities at 0.5% compared to the main peak (100%) could be detected with the multiplexed system which is 10 times lower compared to the single capillary system. Higher efficiency and improved figures of merit (absolute sensitivity and no cross-talk interferences) were obtained by using an array of only 24 capillaries. Copyright © 2011 Elsevier B.V. All rights reserved.

Annealing dependence on flexible p-CuGaO2/n-ZnO heterojunction diode deposited by RF sputtering method

NASA Astrophysics Data System (ADS)

Li Lam, Mui; Hafiz Abu Bakar, Muhammad; Lam, Wai Yip; Alias, Afishah; Rahman, Abu Bakar Abd; Anuar Mohamad, Khairul; Uesugi, Katsuhiro

2017-11-01

In this work, p-CuGaO2/n-ZnO heterojunction diodes were deposited by RF powered sputtering method on polyethylene terephthalate (PETP, PET) substrates. Structural, morphology, optical and electrical properties of CuGaO2/ZnO heterojunction was investigated as a function of annealing duration. The structural properties show the ZnO films (002) peak were stronger at the range of 34° while CuGaO2 (015) peak is not visible at 44°. The surface morphology revealed that RMS roughness become smoother as the annealing duration increase to 30 minutes and become rougher as the annealing duration is increased to 60 minutes. The optical properties of CuGaO2/ZnO heterojunction diode at 30 minutes exhibit approximately 75% optical transmittance in the invisible region. The diodes exhibited a rectifying characteristic and the maximum forward current was observed for the diode annealed for 30 minutes. The diodes show an ideality factor range from 43.69 to 71.29 and turn on voltage between 0.75 V and 1.05 V.

Novel Design of Iridium Phosphors with Pyridinylphosphinate Ligands for High-Efficiency Blue Organic Light-emitting Diodes

PubMed Central

Wu, Zheng-Guang; Jing, Yi-Ming; Lu, Guang-Zhao; Zhou, Jie; Zheng, You-Xuan; Zhou, Liang; Wang, Yi; Pan, Yi

2016-01-01

Due to the high quantum efficiency and wide scope of emission colors, iridium (Ir) (III) complexes have been widely applied as guest materials for OLEDs (organic light-emitting diodes). Contrary to well-developed Ir(III)-based red and green phosphorescent complexes, the efficient blue emitters are rare reported. Like the development of the LED, the absence of efficient and stable blue materials hinders the widely practical application of the OLEDs. Inspired by this, we designed two novel ancillary ligands of phenyl(pyridin-2-yl)phosphinate (ppp) and dipyridinylphosphinate (dpp) for efficient blue phosphorescent iridium complexes (dfppy)2Ir(ppp) and (dfppy)2Ir(dpp) (dfppy = 2-(2,4-difluorophenyl)pyridine) with good electron transport property. The devices using the new iridium phosphors display excellent electroluminescence (EL) performances with a peak current efficiency of 58.78 cd/A, a maximum external quantum efficiency of 28.3%, a peak power efficiency of 52.74 lm/W and negligible efficiency roll-off ratios. The results demonstrated that iridium complexes with pyridinylphosphinate ligands are potential blue phosphorescent materials for OLEDs. PMID:27929124

1300 nm wavelength InAs quantum dot photodetector grown on silicon.

PubMed

Sandall, Ian; Ng, Jo Shien; David, John P R; Tan, Chee Hing; Wang, Ting; Liu, Huiyun

2012-05-07

The optical and electrical properties of InAs quantum dots epitaxially grown on a silicon substrate have been investigated to evaluate their potential as both photodiodes and avalanche photodiodes (APDs) operating at a wavelength of 1300 nm. A peak responsivity of 5 mA/W was observed at 1280 nm, with an absorption tail extending beyond 1300 nm, while the dark currents were two orders of magnitude lower than those reported for Ge on Si photodiodes. The diodes exhibited avalanche breakdown at 22 V reverse bias which is probably dominated by impact ionisation occurring in the GaAs and AlGaAs barrier layers. A red shift in the absorption peak of 61.2 meV was measured when the reverse bias was increased from 0 to 22 V, which we attributed to the quantum confined stark effect. This shift also leads to an increase in the responsivity at a fixed wavelength as the bias is increased, yielding a maximum increase in responsivity by a factor of 140 at the wavelength of 1365 nm, illustrating the potential for such a structure to be used as an optical modulator.

A system for applying rapid warming or cooling stimuli to cells during patch clamp recording or ion imaging.

PubMed

Reid, G; Amuzescu, B; Zech, E; Flonta, M L

2001-10-15

We describe a system for superfusing small groups of cells at a precisely controlled and rapidly adjustable local temperature. Before being applied to the cell or cells under study, solutions are heated or cooled in a chamber of small volume ( approximately 150 microl) and large surface area, sandwiched between four small Peltier elements. The current through the Peltier elements is controlled by a microprocessor using a PID (proportional-integral-derivative) feedback algorithm. The chamber can be heated to at least 60 degrees C and cooled to 0 degrees C, changing its temperature at a maximum rate of about 7 degrees C per second; temperature ramps can be followed under feedback control at up to 4 degrees C per second. Temperature commands can be applied from the digital-to-analogue converter of any laboratory interface or generated digitally by the microprocessor. The peak-to-peak noise contributed by the system does not exceed that contributed by a patch pipette, holder and headstage, making it suitable for single channel as well as whole cell recordings.

DFT calculations of graphene monolayer in presence of Fe dopant and vacancy

NASA Astrophysics Data System (ADS)

Ostovari, Fatemeh; Hasanpoori, Marziyeh; Abbasnejad, Mohaddeseh; Salehi, Mohammad Ali

2018-07-01

In the present work, the effects of Fe doping and vacancies on the electronic, magnetic and optical properties of graphene are studied by density functional theory based calculations. The conductive behavior is revealed for the various defected graphene by means of electronic density of states. However, defected structures show different magnetic and optical properties compared to those of pure one. The ferromagnetic phase is the most probable phase by substituting Fe atoms and vacancies at AA sublattice of graphene. The optical properties of impure graphene differ from pure graphene under illumination with parallel polarization of electric field, whereas for perpendicular polarization it remains unchanged. In presence of defect and under parallel polarization of light, the static dielectric constant rises strongly and the maximum peak of Im ε(ω) shows red shift relative to pure graphene. Moreover, the maximum absorption peak gets broaden in the visible to infrared region at the same condition and the magnitude and related energy of peaks shift to higher value in the EELS spectra. Furthermore, the results show that the maximum values of refractive index and reflectivity spectra increase rapidly and represent the red and blue shifts; respectively. Generally; substituting the C atom with Fe has more effect on magnetic and optical properties relative to the C vacancies.

F-18 high alpha research vehicle surface pressures: Initial in-flight results and correlation with flow visualization and wind-tunnel data

NASA Technical Reports Server (NTRS)

Fisher, David F.; Banks, Daniel W.; Richwine, David M.

1990-01-01

Pressure distributions measured on the forebody and the leading-edge extensions (LEX's) of the NASA F-18 high alpha research vehicle (HARV) were reported at 10 and 50 degree angles of attack and at Mach 0.20 to 0.60. The results were correlated with HARV flow visualization and 6-percent scale F-18 wind-tunnel-model test results. The general trend in the data from the forebody was for the maximum suction pressure peaks to first appear at an angle of attack (alpha) of approximately 19 degrees and increase in magnitude with angle of attack. The LEX pressure distribution general trend was the inward progression and increase in magnitude of the maximum suction peaks up to vortex core breakdown and then the decrease and general flattening of the pressure distribution beyond that. No significant effect of Mach number was noted for the forebody results. However, a substantial compressibility effect on the LEX's resulted in a significant reduction in vortex-induced suction pressure as Mach number increased. The forebody primary and the LEX secondary vortex separation lines, from surface flow visualization, correlated well with the end of pressure recovery, leeward and windward, respectively, of maximum suction pressure peaks. The flight to wind-tunnel correlations were generally good with some exceptions.

Evaluation of hearing protection used by police officers in the shooting range.

PubMed

Guida, Heraldo Lorena; Taxini, Carla Linhares; Gonçalves, Claudia Giglio de Oliveira; Valenti, Vitor Engrácia

2014-01-01

Impact noise is characterized by acoustic energy peaks that last less than a second, at intervals of more than 1s. To quantify the levels of impact noise to which police officers are exposed during activities at the shooting range and to evaluate the attenuation of the hearing protector. Measurements were performed in the shooting range of a military police department. An SV 102 audiodosimeter (Svantek) was used to measure sound pressure levels. Two microphones were used simultaneously: one external and one insertion type; the firearm used was a 0.40 Taurus® rimless pistol. The values obtained with the external microphone were 146 dBC (peak), and a maximum sound level of 129.4 dBC (fast). The results obtained with the insertion microphone were 138.7 dBC (peak), and a maximum sound level of 121.6 dBC (fast). The findings showed high levels of sound pressure in the shooting range, which exceeded the maximum recommended noise (120 dBC), even when measured through the insertion microphone. Therefore, alternatives to improve the performance of hearing protection should be considered. Copyright © 2014 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Analysis of Japanese Radionuclide Monitoring Data of Food Before and After the Fukushima Nuclear Accident

PubMed Central

2015-01-01

In an unprecedented food monitoring campaign for radionuclides, the Japanese government took action to secure food safety after the Fukushima nuclear accident (Mar. 11, 2011). In this work we analyze a part of the immense data set, in particular radiocesium contaminations in food from the first year after the accident. Activity concentrations in vegetables peaked immediately after the campaign had commenced, but they decreased quickly, so that by early summer 2011 only a few samples exceeded the regulatory limits. Later, accumulating mushrooms and dried produce led to several exceedances of the limits again. Monitoring of meat started with significant delay, especially outside Fukushima prefecture. After a buildup period, contamination levels of meat peaked by July 2011 (beef). Levels then decreased quickly, but peaked again in September 2011, which was primarily due to boar meat (a known accumulator of radiocesium). Tap water was less contaminated; any restrictions for tap water were canceled by April 1, 2011. Pre-Fukushima 137Cs and 90Sr levels (resulting from atmospheric nuclear explosions) in food were typically lower than 0.5 Bq/kg, whereby meat was typically higher in 137Cs and vegetarian produce was usually higher in 90Sr. The correlation of background radiostrontium and radiocesium indicated that the regulatory assumption after the Fukushima accident of a maximum activity of 90Sr being 10% of the respective 137Cs concentrations may soon be at risk, as the 90Sr/137Cs ratio increases with time. This should be taken into account for the current Japanese food policy as the current regulation will soon underestimate the 90Sr content of Japanese foods. PMID:25621976

Cloud-to-ground lightning activity in Colombia: A 14-year study using lightning location system data

NASA Astrophysics Data System (ADS)

Herrera, J.; Younes, C.; Porras, L.

2018-05-01

This paper presents the analysis of 14 years of cloud-to-ground lightning activity observation in Colombia using lightning location systems (LLS) data. The first Colombian LLS operated from 1997 to 2001. After a few years, this system was upgraded and a new LLS has been operating since 2007. Data obtained from these two systems was analyzed in order to obtain lightning parameters used in designing lightning protection systems. The flash detection efficiency was estimated using average peak current maps and some theoretical results previously published. Lightning flash multiplicity was evaluated using a stroke grouping algorithm resulting in average values of about 1.0 and 1.6 for positive and negative flashes respectively and for both LLS. The time variation of this parameter changes slightly for the years considered in this study. The first stroke peak current for negative and positive flashes shows median values close to 29 kA and 17 kA respectively for both networks showing a great dependence on the flash detection efficiency. The average percentage of negative and positive flashes shows a 74.04% and 25.95% of occurrence respectively. The daily variation shows a peak between 23 and 02 h. The monthly variation of this parameter exhibits a bimodal behavior typical of the regions located near The Equator. The lightning flash density was obtained dividing the study area in 3 × 3 km cells and resulting in maximum average values of 25 and 35 flashes km- 2 year- 1 for each network respectively. A comparison of these results with global lightning activity hotspots was performed showing good correlation. Besides, the lightning flash density variation with altitude shows an inverse relation between these two variables.

Impact of cardiosynchronous brain pulsations on Monte Carlo calculated doses for synchrotron micro- and minibeam radiation therapy.

PubMed

Manchado de Sola, Francisco; Vilches, Manuel; Prezado, Yolanda; Lallena, Antonio M

2018-05-15

The purpose of this study was to assess the effects of brain movements induced by heartbeat on dose distributions in synchrotron micro- and minibeam radiation therapy and to develop a model to help guide decisions and planning for future clinical trials. The Monte Carlo code PENELOPE was used to simulate the irradiation of a human head phantom with a variety of micro- and minibeam arrays, with beams narrower than 100 μm and above 500 μm, respectively, and with radiation fields of 1 × 2 cm and 2 × 2 cm. The dose in the phantom due to these beams was calculated by superposing the dose profiles obtained for a single beam of 1 μm × 2 cm. A parameter δ, accounting for the total displacement of the brain during the irradiation and due to the cardiosynchronous pulsation, was used to quantify the impact on peak-to-valley dose ratios and the full width at half maximum. The difference between the maximum (at the phantom entrance) and the minimum (at the phantom exit) values of the peak-to-valley dose ratio reduces when the parameter δ increases. The full width at half maximum remains almost constant with depth for any δ value. Sudden changes in the two quantities are observed at the interfaces between the various tissues (brain, skull, and skin) present in the head phantom. The peak-to-valley dose ratio at the center of the head phantom reduces when δ increases, remaining above 70% of the static value only for minibeams and δ smaller than ∼200 μm. Optimal setups for brain treatments with synchrotron radiation micro- and minibeam combs depend on the brain displacement due to cardiosynchronous pulsation. Peak-to-valley dose ratios larger than 90% of the maximum values obtained in the static case occur only for minibeams and relatively large dose rates. © 2018 American Association of Physicists in Medicine.

Probable flood predictions in ungauged coastal basins of El Salvador

USGS Publications Warehouse

Friedel, M.J.; Smith, M.E.; Chica, A.M.E.; Litke, D.

2008-01-01

A regionalization procedure is presented and used to predict probable flooding in four ungauged coastal river basins of El Salvador: Paz, Jiboa, Grande de San Miguel, and Goascoran. The flood-prediction problem is sequentially solved for two regions: upstream mountains and downstream alluvial plains. In the upstream mountains, a set of rainfall-runoff parameter values and recurrent peak-flow discharge hydrographs are simultaneously estimated for 20 tributary-basin models. Application of dissimilarity equations among tributary basins (soft prior information) permitted development of a parsimonious parameter structure subject to information content in the recurrent peak-flow discharge values derived using regression equations based on measurements recorded outside the ungauged study basins. The estimated joint set of parameter values formed the basis from which probable minimum and maximum peak-flow discharge limits were then estimated revealing that prediction uncertainty increases with basin size. In the downstream alluvial plain, model application of the estimated minimum and maximum peak-flow hydrographs facilitated simulation of probable 100-year flood-flow depths in confined canyons and across unconfined coastal alluvial plains. The regionalization procedure provides a tool for hydrologic risk assessment and flood protection planning that is not restricted to the case presented herein. ?? 2008 ASCE.

Temporal Variability of Daily Personal Magnetic Field Exposure Metrics in Pregnant Women

PubMed Central

Lewis, Ryan C.; Evenson, Kelly R.; Savitz, David A.; Meeker, John D.

2015-01-01

Recent epidemiology studies of power-frequency magnetic fields and reproductive health have characterized exposures using data collected from personal exposure monitors over a single day, possibly resulting in exposure misclassification due to temporal variability in daily personal magnetic field exposure metrics, but relevant data in adults are limited. We assessed the temporal variability of daily central tendency (time-weighted average, median) and peak (upper percentiles, maximum) personal magnetic field exposure metrics over seven consecutive days in 100 pregnant women. When exposure was modeled as a continuous variable, central tendency metrics had substantial reliability, whereas peak metrics had fair (maximum) to moderate (upper percentiles) reliability. The predictive ability of a single day metric to accurately classify participants into exposure categories based on a weeklong metric depended on the selected exposure threshold, with sensitivity decreasing with increasing exposure threshold. Consistent with the continuous measures analysis, sensitivity was higher for central tendency metrics than for peak metrics. If there is interest in peak metrics, more than one day of measurement is needed over the window of disease susceptibility to minimize measurement error, but one day may be sufficient for central tendency metrics. PMID:24691007

Miniaturized power limiter metasurface based on Fano-type resonance and Babinet principle.

PubMed

Loo, Y L; Wang, H G; Zhang, H; Ong, C K

2016-09-05

In this work, we present a miniaturize power limiter, a device with size smaller than that required by the working frequency, made of coupled self-complementary electric inductive-capacitive (CELC) resonator and original electric inductive-capacitive (ELC) structure. We also make use of Babinet principle to ensure both CELC and ELC are resonating at the same frequency. The CELC structure is loaded with a Schottky diode to achieve the effect of a nonlinear power limiter. The constructive interference of CELC and ELC structure produces a new Fano-type resonance peak at a lower frequency. The Fano peak is sharp and able to concentrate electric field at a region between the inner and outer metallic patch of the metastructure, hence enhancing the nonlinear properties of the loaded diode. The Fano peak enhances the maximum isolation of the power limiter due to the local field enhancement at where the diode is loaded. Numerical simulation and experiment are conducted in the S-band frequency to verify the power limiting effect of the device designed and to discuss the formation of Fano peak. The power limiter designed has a maximum isolation of 8.4 dB and a 3-dB isolation bandwidth of 6%.

Long-range wind monitoring in real time with optimized coherent lidar

NASA Astrophysics Data System (ADS)

Dolfi-Bouteyre, Agnes; Canat, Guillaume; Lombard, Laurent; Valla, Matthieu; Durécu, Anne; Besson, Claudine

2017-03-01

Two important enabling technologies for pulsed coherent detection wind lidar are the laser and real-time signal processing. In particular, fiber laser is limited in peak power by nonlinear effects, such as stimulated Brillouin scattering (SBS). We report on various technologies that have been developed to mitigate SBS and increase peak power in 1.5-μm fiber lasers, such as special large mode area fiber designs or strain management. Range-resolved wind profiles up to a record range of 16 km within 0.1-s averaging time have been obtained thanks to those high-peak power fiber lasers. At long range, the lidar signal gets much weaker than the noise and special care is required to extract the Doppler peak from the spectral noise. To optimize real-time processing for weak carrier-to-noise ratio signal, we have studied various Doppler mean frequency estimators (MFE) and the influence of data accumulation on outliers occurrence. Five real-time MFEs (maximum, centroid, matched filter, maximum likelihood, and polynomial fit) have been compared in terms of error and processing time using lidar experimental data. MFE errors and data accumulation limits are established using a spectral method.

Properties of micro-arc oxidation coatings on aluminum alloy at different negative peak current densities

NASA Astrophysics Data System (ADS)

Gu, Xin; Jiang, Bailing; Li, Hongtao; Liu, Cancan; Shao, Lianlian

2018-05-01

Micro-arc oxidation coatings were fabricated on 6061 aluminum alloy using whereby bipolar pulse mode in the case of different negative peak current densities. The phase composition, microstructures and wear properties were studied using x-ray diffraction, scanning electron microscopy and ball-on-disk wear tester, respectively. As results indicate, by virtue of negative peak current density, the oxygen can be expelled by produced hydrogen on anode in the case of negative pulse width and via the opened discharge channel. The results of x-ray diffraction, surface and cross-sectional morphology indicated that the coating was structured compactly taking on less small-diameter micro-pores and defects with negative peak current density of 75 A dm‑2. Additionally, as the results of wear tracks and weight loss bespeak, by virtue of appropriate negative peak current density, coatings resisted the abrasive wear and showed excellent wear resistance.

Energy and public health: the challenge of peak petroleum.

PubMed

Frumkin, Howard; Hess, Jeremy; Vindigni, Stephen

2009-01-01

Petroleum is a unique and essential energy source, used as the principal fuel for transportation, in producing many chemicals, and for numerous other purposes. Global petroleum production is expected to reach a maximum in the near future and to decline thereafter, a phenomenon known as "peak petroleum." This article reviews petroleum geology and uses, describes the phenomenon of peak petroleum, and reviews the scientific literature on the timing of this transition. It then discusses how peak petroleum may affect public health and health care, by reference to four areas: medical supplies and equipment, transportation, energy generation, and food production. Finally, it suggests strategies for anticipating and preparing for peak petroleum, both general public health preparedness strategies and actions specific to the four expected health system impacts.

Increased in-shoe lateral plantar pressures with chronic ankle instability.

PubMed

Schmidt, Heather; Sauer, Lindsay D; Lee, Sae Yong; Saliba, Susan; Hertel, Jay

2011-11-01

Previous plantar pressure research found increased loads and slower loading response on the lateral aspect of the foot during gait with chronic ankle instability compared to healthy controls. The studies had subjects walking barefoot over a pressure mat and results have not been confirmed with an in-shoe plantar pressure system. Our purpose was to report in-shoe plantar pressure measures for chronic ankle instability subjects compared to healthy controls. Forty-nine subjects volunteered (25 healthy controls, 24 chronic ankle instability) for this case-control study. Subjects jogged continuously on a treadmill at 2.68 m/s (6.0 mph) while three trials of ten consecutive steps were recorded. Peak pressure, time-to-peak pressure, pressure-time integral, maximum force, time-to-maximum force, and force-time integral were assessed in nine regions of the foot with the Pedar-x in-shoe plantar pressure system (Novel, Munich, Germany). Chronic ankle instability subjects demonstrated a slower loading response in the lateral rearfoot indicated by a longer time-to-peak pressure (16.5% +/- 10.1, p = 0.001) and time-to-maximum force (16.8% +/- 11.3, p = 0.001) compared to controls (6.5% +/- 3.7 and 6.6% +/- 5.5, respectively). In the lateral midfoot, ankle instability subjects demonstrated significantly greater maximum force (318.8 N +/- 174.5, p = 0.008) and peak pressure (211.4 kPa +/- 57.7, p = 0.008) compared to controls (191.6 N +/- 74.5 and 161.3 kPa +/- 54.7). Additionally, ankle instability subjects demonstrated significantly higher force-time integral (44.1 N/s +/- 27.3, p = 0.005) and pressure-time integral (35.0 kPa/s +/- 12.0, p = 0.005) compared to controls (23.3 N/s +/- 10.9 and 24.5 kPa/s +/- 9.5). In the lateral forefoot, ankle instability subjects demonstrated significantly greater maximum force (239.9N +/- 81.2, p = 0.004), force-time integral (37.0 N/s +/- 14.9, p = 0.003), and time-to-peak pressure (51.1% +/- 10.9, p = 0.007) compared to controls (170.6 N +/- 49.3, 24.3 N/s +/- 7.2 and 43.8% +/- 4.3). Using an in-shoe plantar pressure system, chronic ankle instability subjects had greater plantar pressures and forces in the lateral foot compared to controls during jogging. These findings may have implications in the etiology and treatment of chronic ankle instability.

A comparison of lead pollution record in Sphagnum peat with known historical Pb emission rates in the British Isles and the Czech Republic

NASA Astrophysics Data System (ADS)

Novak, Martin; Erel, Yigal; Zemanova, Leona; Bottrell, Simon H.; Adamova, Marie

Vertical Pb concentration gradients and isotope ratios ( 206Pb/ 207Pb, 208Pb/ 207Pb) are reported for five 210Pb-dated Sphagnum peat profiles. The studied peat bogs are in the British Isles (Thorne Moors, England; Mull, Scotland; and Connemara, Eire) and central Europe (Ocean, northern Czech Republic; Rybarenska slat, southern Czech Republic). Both the U.K. and the Czech Republic experienced maximum Pb emissions from Ag-Pb smelting around 1880. Pb emissions from coal burning peaked in 1955 in the U.K. and in the 1980s in the Czech Republic. In both countries, use of alkyl-lead additives to gasoline resulted in large Pb emissions between 1950 and 2000. We hypothesized that peaks in Pb emissions from smelting, coal burning and gasoline burning, respectively, should be mirrored in the peat profiles. However, a more complicated pattern emerged. Maximum annual Pb accumulation rates occurred in 1870 at Ocean, 1940 at Thorne Moors, 1988 at Rybarenska slat, and 1990 at Mull and Connemara. Atmospheric Pb inputs decreased in the order Thorne Moors ≥ Ocean > Rybarenska slat > Mull > Connemara. The Ocean bog was unique in the central European region in that its maximum Pb pollution dated back to the 19th century and coincided with maximum Pb smelting at Freiberg and Pribram. In contrast, numerous previously studied sites showed no Pb accumulation maximum in the 19th century, but increasing pollution until the 1980s. It remains unclear why Ocean did not record the regional peak in Pb emissions caused by high coal and gasoline burning around 1980, while an array of nearby bogs studied previously did record the 1980 coal/gasoline peak, but no 1880 smelting peak. Mean 206Pb/ 207Pb ratios of potential pollution sources were 1.07 and 1.11 for gasoline, 1.17 and 1.17 for local ores, and 1.18 and 1.19 for coal in the U.K. and the Czech Republic, respectively. The calculated percentages of gasoline-derived Pb in peat (≤55% for the British Isles and ≤63% for the Czech Republic) were surprisingly low. An explanation for the low percentage of gasoline-derived Pb in peat can be more easily found for the Czech sites (until 1989 Czechoslovakia was the third largest lignite producer in the world). Regional differences in deposition rates of gasoline-derived Pb in the U.K. need further study.

Mathematical model of a parallel plate ammonia electrolyzer for combined wastewater remediation and hydrogen production.

PubMed

Estejab, Ali; Daramola, Damilola A; Botte, Gerardine G

2015-06-15

A mathematical model was developed for the simulation of a parallel plate ammonia electrolyzer to convert ammonia in wastewater to nitrogen and hydrogen under basic conditions. The model consists of fundamental transport equations, the ammonia oxidation kinetics at the anode, and the hydrogen evolution kinetics at the cathode of the electrochemical reactor. The model shows both qualitative and quantitative agreement with experimental measurements at ammonia concentrations found within wastewater (200-1200 mg L(-1)). The optimum electrolyzer performance is dependent on both the applied voltage and the inlet concentrations. Maximum conversion of ammonia to nitrogen at the rates of 0.569 and 0.766 mg L(-1) min(-1) are achieved at low (0.01 M NH4Cl and 0.1 M KOH) and high (0.07 M NH4Cl and 0.15 M KOH) inlet concentrations, respectively. At high and low concentrations, an initial increase in the cell voltage will cause an increase in the system response - current density generated and ammonia converted. These system responses will approach a peak value before they start to decrease due to surface blockage and/or depletion of solvated species at the electrode surface. Furthermore, the model predicts that by increasing the reactant and electrolyte concentrations at a certain voltage, the peak current density will plateau, showing an asymptotic response. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spatially variant red blood cell crenation in alternating current non-uniform fields.

PubMed

An, Ran; Wipf, David O; Minerick, Adrienne R

2014-03-01

Alternating-current (AC) electrokinetics involve the movement and behaviors of particles or cells. Many applications, including dielectrophoretic manipulations, are dependent upon charge interactions between the cell or particle and the surrounding medium. Medium concentrations are traditionally treated as spatially uniform in both theoretical models and experiments. Human red blood cells (RBCs) are observed to crenate, or shrink due to changing osmotic pressure, over 10 min experiments in non-uniform AC electric fields. Cell crenation magnitude is examined as functions of frequency from 250 kHz to 1 MHz and potential from 10 Vpp to 17.5 Vpp over a 100 μm perpendicular electrode gap. Experimental results show higher peak to peak potential and lower frequency lead to greater cell volume crenation up to a maximum volume loss of 20%. A series of experiments are conducted to elucidate the physical mechanisms behind the red blood cell crenation. Non-uniform and uniform electrode systems as well as high and low ion concentration experiments are compared and illustrate that AC electroporation, system temperature, rapid temperature changes, medium pH, electrode reactions, and convection do not account for the crenation behaviors observed. AC electroosmotic was found to be negligible at these conditions and AC electrothermal fluid flows were found to reduce RBC crenation behaviors. These cell deformations were attributed to medium hypertonicity induced by ion concentration gradients in the spatially nonuniform AC electric fields.

Fabrication of a transparent ultraviolet detector by using n-type Ga2O3 and p-type Ga-doped SnO2 core-shell nanowires.

PubMed

Hsu, Cheng-Liang; Lu, Ying-Ching

2012-09-21

This study investigates the feasibility of synthesizing high-density transparent Ga(2)O(3)/SnO(2):Ga core-shell nanowires on a sapphire substrate at 1000 °C by VLS. The doping Ga concentrations are 0.46, 1.07, 2.30 and 17.53 atomic%. The XRD spectrum and HR-TEM reveal Ga(2)O(3) and SnO(2) as having monoclinic and tetragonal rutile structures, respectively. Experimental results indicate that the XRD peak shift of SnO(2) to a larger angle increases with the increasing amount of Ga doping. According to the CL spectrum, SnO(2) and Ga(2)O(3) peak at approximately 528-568 nm and 422-424 nm, respectively. The maximum quantum efficiency of Ga(2)O(3)/SnO(2):Ga core-shell nanowires is around 0.362%. The UV light on-off current contrast ratio of Ga(2)O(3)/SnO(2):Ga core-shell nanowires is around 1066.7 at a bias of 5 V. Moreover, the dynamic response of Ga(2)O(3)/SnO(2):Ga core-shell nanowires has an on-off current contrast ratio of around 16. Furthermore, the Ga(2)O(3) region functions similar to a capacitor and continues to accumulate SnO(2):Ga excited electrons under UV light exposure.

Aerothermodynamic Design of the Mars Science Laboratory Heatshield

NASA Technical Reports Server (NTRS)

Edquist, Karl T.; Dyakonov, Artem A.; Wright, Michael J.; Tang, Chun Y.

2009-01-01

Aerothermodynamic design environments are presented for the Mars Science Laboratory entry capsule heatshield. The design conditions are based on Navier-Stokes flowfield simulations on shallow (maximum total heat load) and steep (maximum heat flux, shear stress, and pressure) entry trajectories from a 2009 launch. Boundary layer transition is expected prior to peak heat flux, a first for Mars entry, and the heatshield environments were defined for a fully-turbulent heat pulse. The effects of distributed surface roughness on turbulent heat flux and shear stress peaks are included using empirical correlations. Additional biases and uncertainties are based on computational model comparisons with experimental data and sensitivity studies. The peak design conditions are 197 W/sq cm for heat flux, 471 Pa for shear stress, 0.371 Earth atm for pressure, and 5477 J/sq cm for total heat load. Time-varying conditions at fixed heatshield locations were generated for thermal protection system analysis and flight instrumentation development. Finally, the aerothermodynamic effects of delaying launch until 2011 are previewed.

Flood hydrology for Dry Creek, Lake County, Northwestern Montana

USGS Publications Warehouse

Parrett, C.; Jarrett, R.D.

2004-01-01

Dry Creek drains about 22.6 square kilometers of rugged mountainous terrain upstream from Tabor Dam in the Mission Range near St. Ignatius, Montana. Because of uncertainty about plausible peak discharges and concerns regarding the ability of the Tabor Dam spillway to safely convey these discharges, the flood hydrology for Dry Creek was evaluated on the basis of three hydrologic and geologic methods. The first method involved determining an envelope line relating flood discharge to drainage area on the basis of regional historical data and calculating a 500-year flood for Dry Creek using a regression equation. The second method involved paleoflood methods to estimate the maximum plausible discharge for 35 sites in the study area. The third method involved rainfall-runoff modeling for the Dry Creek basin in conjunction with regional precipitation information to determine plausible peak discharges. All of these methods resulted in estimates of plausible peak discharges that are substantially less than those predicted by the more generally applied probable maximum flood technique. Copyright ASCE 2004.

Synthesis and application of a highly selective copper ions fluorescent probe based on the coumarin group

NASA Astrophysics Data System (ADS)

He, Guangjie; Liu, Xiangli; Xu, Jinhe; Ji, Liguo; Yang, Linlin; Fan, Aiying; Wang, Songjun; Wang, Qingzhi

2018-02-01

A highly selective copper ions fluorescent probe based on the coumarin-type Schiff base derivative 1 (probe) was produced by condensation reaction between coumarin carbohydrazide and 1H-indazole-3-carbaldehyde. The UV-vis spectroscopy showed that the maximum absorption peak of compound 1 appeared at 439 nm. In the presence of Cu2 + ions, the maximum peak decreased remarkably compared with other physiological important metal ions and a new absorption peak at 500 nm appeared. The job's plot experiments showed that complexes of 1:2 binding mode were formed in CH3CN:HEPES (3:2, v/v) solution. Compound 1 exhibited a strong blue fluorescence. Upon addition of copper ions, the fluorescence gradually decreased and reached a plateau with the fluorescence quenching rate up to 98.73%. The detection limit for Cu2 + ions was estimated to 0.384 ppm. Fluorescent microscopy experiments demonstrated that probe 1 had potential to be used to investigate biological processes involving Cu2 + ions within living cells.

Enhancement of magneto-optical Faraday effects and extraordinary optical transmission in a tri-layer structure with rectangular annular arrays.

PubMed

Lei, Chengxin; Chen, Leyi; Tang, Zhixiong; Li, Daoyong; Cheng, Zhenzhi; Tang, Shaolong; Du, Youwei

2016-02-15

The properties of optics and magneto-optical Faraday effects in a metal-dielectric tri-layer structure with subwavelength rectangular annular arrays are investigated. It is noteworthy that we obtained the strongly enhanced Faraday rotation of the desired sign along with high transmittance by optimizing the parameters of the nanostructure in the visible spectral ranges. In this system, we obtained two extraordinary optical transmission (EOT) resonant peaks with enhanced Faraday rotations, whose signs are opposite, which may provide the possibility of designing multi-channel magneto-optical devices. Study results show that the maximum of the figure of merit (FOM) of the structure can be obtained between two EOT resonant peaks accompanied by an enhanced Faraday rotation. The positions of the maximum value of the FOM and resonant peaks of transmission along with a large Faraday rotation can be tailored by simply adjusting the geometric parameters of our models. These research findings are of great importance for future applications of magneto-optical devices.

Method and apparatus for clockless analog-to-digital conversion and peak detection

DOEpatents

DeGeronimo, Gianluigi

2007-03-06

An apparatus and method for analog-to-digital conversion and peak detection includes at least one stage, which includes a first switch, second switch, current source or capacitor, and discriminator. The discriminator changes state in response to a current or charge associated with the input signal exceeding a threshold, thereby indicating whether the current or charge associated with the input signal is greater than the threshold. The input signal includes a peak or a charge, and the converter includes a peak or charge detect mode in which a state of the switch is retained in response to a decrease in the current or charge associated with the input signal. The state of the switch represents at least a portion of a value of the peak or of the charge.

WE-E-17A-01: Characterization of An Imaging-Based Model of Tumor Angiogenesis

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

Adhikarla, V; Jeraj, R

2014-06-15

Purpose: Understanding the transient dynamics of tumor oxygenation is important when evaluating tumor-vasculature response to anti-angiogenic therapies. An imaging-based tumor-vasculature model was used to elucidate factors that affect these dynamics. Methods: Tumor growth depends on its doubling time (Td). Hypoxia increases pro-angiogenic factor (VEGF) concentration which is modeled to reduce vessel perfusion, attributing to its effect of increasing vascular permeability. Perfused vessel recruitment depends on the existing perfused vasculature, VEGF concentration and maximum VEGF concentration (VEGFmax) for vessel dysfunction. A convolution-based algorithm couples the tumor to the normal tissue vessel density (VD-nt). The parameters are benchmarked to published pre-clinical datamore » and a sensitivity study evaluating the changes in the peak and time to peak tumor oxygenation characterizes them. The model is used to simulate changes in hypoxia and proliferation PET imaging data obtained using [Cu- 61]Cu-ATSM and [F-18]FLT respectively. Results: Td and VD-nt were found to be the most influential on peak tumor pO2 while VEGFmax was marginally influential. A +20 % change in Td, VD-nt and VEGFmax resulted in +50%, +25% and +5% increase in peak pO2. In contrast, Td was the most influential on the time to peak oxygenation with VD-nt and VEGFmax playing marginal roles. A +20% change in Td, VD-nt and VEGFmax increased the time to peak pO2 by +50%, +5% and +0%. A −20% change in the above parameters resulted in comparable decreases in the peak and time to peak pO2. Model application to the PET data was able to demonstrate the voxel-specific changes in hypoxia of the imaged tumor. Conclusion: Tumor-specific doubling time and vessel density are important parameters to be considered when evaluating hypoxia transients. While the current model simulates the oxygen dynamics of an untreated tumor, incorporation of therapeutic effects can make the model a potent tool for analyzing anti-angiogenic therapies.« less

Metamagnetism and weak ferromagnetism in nickel (II) oxalate crystals

NASA Astrophysics Data System (ADS)

Romero-Tela, E.; Mendoza, M. E.; Escudero, R.

2012-05-01

Microcrystals of orthorhombic nickel (II) oxalate dihydrate were synthesized through a precipitation reaction of aqueous solutions of nickel chloride and oxalic acid. Magnetic susceptibility exhibits a sharp peak at 3.3 K and a broad rounded maximum near 43 K. We associated the lower maximum with a metamagnetic transition that occurs when the magnetic field is about ≥ 3.5 T. The maximum at 43 K is typical of 1D antiferromagnets, whereas weak ferromagnetism behavior was observed in the range of 3.3-43 K.

Observation of emission process in hydrogen-like nitrogen Z-pinch discharge with time integrated soft X-ray spectrum pinhole image

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

Sakai, Y.; Kumai, H.; Nakanishi, Y.

2013-02-15

The emission spectra of hydrogen-like nitrogen Balmer at the wavelength of 13.4 nm in capillary Z-pinch discharge plasma are experimentally examined. Ionization to fully strip nitrogen at the pinch maximum, and subsequent rapid expansion cooling are required to establish the population inversion between the principal quantum number of n = 2 and n = 3. The ionization and recombination processes with estimated plasma parameters are evaluated by utilizing a time integrated spectrum pinhole image containing radial spatial information. A cylindrical capillary plasma is pinched by a triangular pulsed current with peak amplitude of 50 kA and pulse width of 50more » ns.« less

Multi-degree-of-freedom ultrasonic micromotor for guidewire and catheter navigation: The NeuroGlide actuator

NASA Astrophysics Data System (ADS)

Yun, Cheol-Ho; Yeo, Leslie Y.; Friend, James R.; Yan, Bernard

2012-04-01

A 240-μm diameter ultrasonic micromotor is presented as a potential solution for an especially difficult task in minimally invasive neurosurgery, navigating a guidewire to an injury in the neurovasculature as the first step of surgery. The peak no-load angular velocity and maximum torque were 600 rad/s and 1.6 nN-m, respectively, and we obtained rotation about all three axes. By using a burst drive scheme, open-loop position and speed control were achieved. The construction method and control scheme proposed in this study remove most of the current limitations in minimally invasive, catheter-based actuation, enabling minimally invasive vascular surgery concepts to be pursued for a broad variety of applications.

Spot size measurement of a flash-radiography source using the pinhole imaging method

NASA Astrophysics Data System (ADS)

Wang, Yi; Li, Qin; Chen, Nan; Cheng, Jin-Ming; Xie, Yu-Tong; Liu, Yun-Long; Long, Quan-Hong

2016-07-01

The spot size of the X-ray source is a key parameter of a flash-radiography facility, and is usually quoted as an evaluation of the resolving power. The pinhole imaging technique is applied to measure the spot size of the Dragon-I linear induction accelerator, by which a two-dimensional spatial distribution of the source spot is obtained. Experimental measurements are performed to measure the spot image when the transportation and focusing of the electron beam are tuned by adjusting the currents of solenoids in the downstream section. The spot size of full-width at half maximum and that defined from the spatial frequency at half peak value of the modulation transfer function are calculated and discussed.

Stratospheric Ozone Climatology from Lidar Measurements at Table Mountain (34.0 deg N, 117.7 deg W) and Mauna Loa (19.5 deg N, 155.6 deg W)

NASA Technical Reports Server (NTRS)

Leblanc, T.; McDermid, I. S.

2000-01-01

Using more than 1600 nighttime profiles obtained by the JPL differential absorption lidars (DIAL) located at Table Mountain Facility (TMF, 34.4 N) and Mauna Loa Observatory (MLO, 19.5 N) is presented in this paper. These two systems have been providing high-resolution vertical profiles of ozone number density between 15-50 km, several nights a week since 1989 (TMF) and 1993 (MLO). The climatology presented here is typical of early night ozone values with only a small influence of the Pinatubo aerosols and the 11-year solar cycle. The observed seasonal and vertical structure of the ozone concentration at TMF is consistent with that typical of mid- to subtropical latitudes. A clear annual cycle in opposite phase below and above the ozone concentration peak is observed. The observed winter maximum below the ozone peak is associated with a maximum day-to-day variability, typical of a dynamically driven lower stratosphere. The maximum concentration observed in summer above the ozone peak emphasizes the more dominant role of photochemistry. Unlike TMF, the ozone concentration observed at MLO tends to be higher during the summer months and lower during the winter months throughout the entire stratospheric ozone layer. Only a weak signature of the extra-tropical latitudes is observed near 19-20 km, with a secondary maximum in late winter. The only large variability observed at MLO is associated with the natural variability of the tropical tropopause.

REVERSING CYCLIC ELASTO-PLASTIC DEMANDS ON STRUCTURES DURING STRONG MOTION EARTHQUAKE EXCITATION.

USGS Publications Warehouse

Perez, V.; Brady, A.G.; Safak, E.

1986-01-01

Using the horizontal components from El Centro 1940, Taft 1952, and 4 accelerograms from the San Fernando earthquake of 2/9/71, the time history of the elasto-plastic displacement response was calculated for oscillators having periods within the range of 1 to 6 s and ductility factors within the range of 3 to 6. The Nth largest peak of the elasto-plastic response (N equals 2,4,8,16), when expressed as a percentage of maximum response (that is, N equals 1), is fairly independent of period within our period range. When considering only plastic peaks occurring, sometimes in a one-directional group of peaks, in the reverse direction from the preceding plastic peak, the amplitude of the Nth reversing plastic peak is similar to the Nth elastic peak, regardless of the ductility factor.

Mechanisms Underlying Isovolumic Contraction and Ejection Peaks in Seismocardiogram Morphology

PubMed Central

Gurev, Viatcheslav; Tavakolian, Kouhyar; Constantino, Jason; Kaminska, Bozena; Blaber, Andrew P.; Trayanova, Natalia A.

2012-01-01

A three-dimensional (3D) finite element electromechanical model of the heart is employed in simulations of seismocardiograms (SCGs). To simulate SCGs, a previously developed 3D model of ventricular contraction is extended by adding the mechanical interaction of the heart with the chest and internal organs. The proposed model reproduces the major peaks of seismocardiographic signals during the phases of the cardiac cycle. Results indicate that SCGs record the pressure of the heart acting on the ribs. In addition, the model reveals that the rotation of the rib with respect to the heart has a minor effect on seismocardiographic signal morphology during the respiratory cycle. SCGs are obtained from 24 human volunteers and their morphology is analyzed. Experimental results demonstrate that the peak of the maximum acceleration of blood in the aorta occurs at the same time as the global minimum of the SCG. It is confirmed that the first SCG peak after the electrocardiogram R-wave corresponds to aortic valve opening, as determined from the impedance cardiogram (p = 0.92). The simulation results reveal that the SCG peaks corresponding to aortic valve opening and the maximum acceleration of blood in the aorta result from ventricular contraction in the longitudinal direction of the ventricles and a decrease in the dimensions of the ventricles due to the ejection of blood, respectively. PMID:23105942

Gamma-ray spectroscopy and pulse shape discrimination with a plastic scintillator

NASA Astrophysics Data System (ADS)

van Loef, E.; Markosyan, G.; Shirwadkar, U.; McClish, M.; Shah, K.

2015-07-01

The scintillation properties of a novel plastic scintillator loaded with an organolead compound are presented. Under X-ray and gamma-ray excitation, emission is observed peaking at 435 nm. The scintillation light output is 9000 ph/MeV. An energy resolution (full width at half maximum over the peak position) of about 16% was observed for the 662 keV full absorption peak. Excellent pulse shape discrimination between neutrons and gamma-rays with a Figure of Merit of 2.6 at 1 MeVee was observed.

Lahar hazard zones for eruption-generated lahars in the Lassen Volcanic Center, California

USGS Publications Warehouse

Robinson, Joel E.; Clynne, Michael A.

2012-01-01

Lahar deposits are found in drainages that head on or near Lassen Peak in northern California, demonstrating that these valleys are susceptible to future lahars. In general, lahars are uncommon in the Lassen region. Lassen Peak's lack of large perennial snowfields and glaciers limits its potential for lahar development, with the winter snowpack being the largest source of water for lahar generation. The most extensive lahar deposits are related to the May 1915 eruption of Lassen Peak, and evidence for pre-1915 lahars is sparse and spatially limited. The May 1915 eruption of Lassen Peak was a small-volume eruption that generated a snow and hot-rock avalanche, a pyroclastic flow, and two large and four smaller lahars. The two large lahars were generated on May 19 and 22 and inundated sections of Lost and Hat Creeks. We use 80 years of snow depth measurements from Lassen Peak to calculate average and maximum liquid water depths, 2.02 meters (m) and 3.90 m respectively, for the month of May as estimates of the 1915 lahars. These depths are multiplied by the areal extents of the eruptive deposits to calculate a water volume range, 7.05-13.6x106 cubic meters (m3). We assume the lahars were a 50/50 mix of water and sediment and double the water volumes to provide an estimate of the 1915 lahars, 13.2-19.8x106 m3. We use a representative volume of 15x106 m3 in the software program LAHARZ to calculate cross-sectional and planimetric areas for the 1915 lahars. The resultant lahar inundation zone reasonably portrays both of the May 1915 lahars. We use this same technique to calculate the potential for future lahars in basins that head on or near Lassen Peak. LAHARZ assumes that the total lahar volume does not change after leaving the potential energy, H/L, cone (the height of the edifice, H, down to the approximate break in slope at its base, L); therefore, all water available to initiate a lahar is contained inside this cone. Because snow is the primary source of water for lahar generation, we assume that the maximum historical water equivalent, 3.90 m, covers the entire basin area inside the H/L cone. The product of planimetric area of each basin inside the H/L and the maximum historical water equivalent yields the maximum water volume available to generate a lahar. We then double the water volumes to approximate maximum lahar volumes. The maximum lahar volumes and an understanding of the statistical uncertainties inherent to the LAHARZ calculations guided our selection of six hypothetical volumes, 1, 3, 10, 30, 60, and 90x106 m3, to delineate concentric lahar inundation zones. The lahar inundation zones extend, in general, tens of kilometers away from Lassen Peak. The small, more-frequent lahar inundation zones (1 and 3x106 m3) are, on average, 10 km long. The exceptions are the zones in Warner Creek and Mill Creek, which extend much further. All but one of the small, more-frequent lahar inundation zones reach outside of the Lassen Volcanic National Park boundary, and the zone in Mill Creek extends well past the park boundary. All of the medium, moderately frequent lahar inundation zones (10 and 30x106 m3) extend past the park boundary and could potentially impact the communities of Viola and Old Station and State Highways 36 and 44, both north and west of Lassen Peak. The approximately 27-km-long on average, large, less-frequent lahar inundation zones (60 and 90x106 m3) represent worst-case lahar scenarios that are unlikely to occur. Flood hazards continue downstream from the toes of the lahars, potentially affecting communities in the Sacramento River Valley.

Combined effect of storm movement and drainage network configuration on flood peaks

NASA Astrophysics Data System (ADS)

Seo, Yongwon; Son, Kwang Ik; Choi, Hyun Il

2016-04-01

This presentation reports the combined effect of storm movement and drainage network layout on resulting hydrographs and its implication to flood process and also flood mitigation. First, we investigate, in general terms, the effects of storm movement on the resulting flood peaks, and the underlying process controls. For this purpose, we utilize a broad theoretical framework that uses characteristic time and space scales associated with stationary rainstorms as well as moving rainstorms. For a stationary rainstorm the characteristic timescales that govern the peak response include two intrinsic timescales of a catchment and one extrinsic timescale of a rainstorm. On the other hand, for a moving rainstorm, two additional extrinsic scales are required; the storm travel time and storm size. We show that the relationship between the peak response and the timescales appropriate for a stationary rainstorm can be extended in a straightforward manner to describe the peak response for a moving rainstorm. For moving rainstorms, we show that the augmentation of peak response arises from both effect of overlaying the responses from subcatchments (resonance condition) and effect of increased responses from subcatchments due to increased duration (interdependence), which results in maximum peak response when the moving rainstorm is slower than the channel flow velocity. Second, we show the relation between channel network configurations and hydrograph sensitivity to storm kinematics. For this purpose, Gibbs' model is used to evaluate the network characteristics. The results show that the storm kinematics that produces the maximum peak discharge depends on the network configuration because the resonance condition changes with the network configuration. We show that an "efficient" network layout is more sensitive and results in higher increase in peak response compared to "inefficient" one. These results imply different flood potential risks for river networks depending on network characteristics. In addition, they imply a possibility of an alternative drainage network layout as an effective measure for flood mitigation in urban environments.

Note: An approach to 1000 T using the electro-magnetic flux compression.

PubMed

Nakamura, D; Sawabe, H; Takeyama, S

2018-01-01

The maximum magnetic field obtained by the electro-magnetic flux compression technique was investigated with respect to the initial seed magnetic field. It was found that the reduction in the seed magnetic field from 3.8 T to 3.0 T led to a substantial increase in the final peak magnetic field. The optical Faraday rotation method with a minimal size probe evades disturbances from electromagnetic noise and shockwave effects to detect such final peak fields in a reduced space of an inner wall of the imploding liner. The Faraday rotation signal recorded the maximum magnetic field increased significantly to the highest magnetic field of 985 T approaching 1000 T, ever achieved by the electro-magnetic flux compression technique as an indoor experiment.

Instructional control of an autonomic sexual response1

PubMed Central

Laws, D. R.; Rubin, H. B.

1969-01-01

Four of seven human male subjects developed full penile erections when exposed to erotically stimulating motion pictures. Changes in penile size were detected by a mercury strain gauge transducer and automatically recorded on a continuous paper record. When instructed to inhibit penile erection in the presence of such effective stimulus films, every subject was able to reduce his erection by at least 50%. This inhibition was apparent as long as the instructions were in effect; when the instructions were removed and the film reshown, the erection returned almost to its maximum state. This was true whether the films were presented as few as three or as many as nine times in succession. When instructed to develop an erection in the absence of a film, every subject was able to do so, each reaching a peak of about 30% of his maximum. Such erections had longer latencies to the peak produced and lower maximum levels than those elicited by a film. PMID:16795214

Double Q-switch Ho:Sc2SiO5 laser by acousto-optic modulator combined with Cr2+:ZnSe saturable absorber

NASA Astrophysics Data System (ADS)

Yang, Xiao-tao; Zhang, Peng; Xie, Wen-qiang; Li, Lin-jun

2018-01-01

A double Q-switch (DQS) Ho:Sc2SiO5 laser modulated by a acousto-optic modulators (AOM) combined with a Cr2+:ZnSe saturable absorber (SA) was reported for the first time. The actively Q-switch (AQS) and passively Q-switch (PQS) were also studied. For the DQS mode, a maximum average output power of 2.49 W under the incident pump power of 12.5 W was obtained, corresponding to a slope efficiency of 24%. The characteristics of the DQS Ho:SSO laser versus different repetition frequencies (RF) of the AOM were researched. The maximum single-pulse energy of the DQS Ho:SSO laser was calculated to 1.98 mJ. The maximum peak power of the DQS Ho:SSO laser was 49.5 kW. The output beam quality factor M2 of DQS Ho:SSO laser was measured to be 1.15 with the highest peak power by knife-edge method at different positions.

Innovative conception and performance evaluation of a compact on-site treatment system.

PubMed

Sousa, V P; Chernicharo, C A L

2006-01-01

The purpose of this study was to develop a new configuration for a compact on-site treatment system, which could become an attractive alternative, from technical, economic, social and environmental viewpoints, to the technologies that are currently employed. The treatment unit consists of a cylindrical tank, where half of the volume is used as a modified septic tank and the other half is divided between an anaerobic hybrid reactor and a trickling filter. An intermittent feeding system was used, with minimum, mean and maximum flowrate settings (Qmin = 0.25l.s(-1), Qmean = 0.50l.s(-1) and Qmax = 1.00l.s(-1)), to reflect the actual operating conditions of a compact on-site treatment system serving a typical dwelling. An average 24-hour hydraulic detention time was used, corresponding to a flowrate of 750l.d(-1). High removal efficiencies and low concentrations of COD, BOD and TSS in the final effluent were achieved, even when the unit was exposed to hydraulic loading peaks during feeding periods at maximum flowrate.

Prospect for a 60 GHz multicharged ECR ion source

NASA Astrophysics Data System (ADS)

Thuillier, T.; Bondoux, D.; Angot, J.; Baylac, M.; Froidefond, E.; Jacob, J.; Lamy, T.; Leduc, A.; Sole, P.; Debray, F.; Trophime, C.; Skalyga, V.; Izotov, I.

2018-05-01

The conceptual design of a fourth generation hybrid electron cyclotron resonance (ECR) ion source operated at 60 GHz is proposed. The axial magnetic mirror is generated with a set of three Nb3Sn coils, while the hexapole is made with room temperature (RT) copper coils. The motivations for such a hybrid development are to study further the ECR plasma physics and the intense multicharged ion beams' production and transport at a time when a superconducting (SC) hexapole appears unrealistic at 60 GHz. The RT hexapole coil designed is an evolution of the polyhelix technology developed at the French High Magnetic Field Facility. The axial magnetic field is generated by means of 3 Nb3Sn SC coils operated with a maximum current density of 350 A/mm2 and a maximum coil load line factor of 81%. The ECR plasma chamber resulting from the design features an inner radius of 94 mm and a length of 500 mm. The radial magnetic intensity is 4.1 T at the wall. Characteristic axial mirror peaks are 8 and 4.5 T, with 1.45 T minimum in between.

Plantar pressure and daily cumulative stress in persons affected by leprosy with current, previous and no previous foot ulceration.

PubMed

van Schie, Carine H M; Slim, Frederik J; Keukenkamp, Renske; Faber, William R; Nollet, Frans

2013-03-01

Not only plantar pressure but also weight-bearing activity affects accumulated mechanical stress to the foot and may be related to foot ulceration. To date, activity has not been accounted for in leprosy. The purpose was to compare barefoot pressure, in-shoe pressure and daily cumulative stress between persons affected by leprosy with and without previous or current foot ulceration. Nine persons with current plantar ulceration were compared to 15 with previous and 15 without previous ulceration. Barefoot peak pressure (EMED-X), in-shoe peak pressure (Pedar-X) and daily cumulative stress (in-shoe forefoot pressure time integral×mean daily strides (Stepwatch™ Activity Monitor)) were measured. Barefoot peak pressure was increased in persons with current and previous compared to no previous foot ulceration (mean±SD=888±222 and 763±335 vs 465±262kPa, p<0.05). In-shoe peak pressure was only increased in persons with current compared to without previous ulceration (mean±SD=412±145 vs 269±70kPa, p<0.05). Daily cumulative stress was not different between groups, although persons with current and previous foot ulceration were less active. Although barefoot peak pressure was increased in people with current and previous plantar ulceration, it did not discriminate between these groups. While in-shoe peak pressure was increased in persons with current ulceration, they were less active, resulting in no difference in daily cumulative stress. Increased in-shoe peak pressure suggests insufficient pressure reducing footwear in persons with current ulceration, highlighting the importance of pressure reducing qualities of footwear. Copyright © 2012 Elsevier B.V. All rights reserved.

MERGING GALAXY CLUSTERS: OFFSET BETWEEN THE SUNYAEV-ZEL'DOVICH EFFECT AND X-RAY PEAKS

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

Molnar, Sandor M.; Hearn, Nathan C.; Stadel, Joachim G., E-mail: sandor@phys.ntu.edu.tw

2012-03-20

Galaxy clusters, the most massive collapsed structures, have been routinely used to determine cosmological parameters. When using clusters for cosmology, the crucial assumption is that they are relaxed. However, subarcminute resolution Sunyaev-Zel'dovich (SZ) effect images compared with high-resolution X-ray images of some clusters show significant offsets between the two peaks. We have carried out self-consistent N-body/hydrodynamical simulations of merging galaxy clusters using FLASH to study these offsets quantitatively. We have found that significant displacements result between the SZ and X-ray peaks for large relative velocities for all masses used in our simulations as long as the impact parameters were aboutmore » 100-250 kpc. Our results suggest that the SZ peak coincides with the peak in the pressure times the line-of-sight characteristic length and not the pressure maximum (as it would for clusters in equilibrium). The peak in the X-ray emission, as expected, coincides with the density maximum of the main cluster. As a consequence, the morphology of the SZ signal, and therefore the offset between the SZ and X-ray peaks, change with viewing angle. As an application, we compare the morphologies of our simulated images to observed SZ and X-ray images and mass surface densities derived from weak-lensing observations of the merging galaxy cluster CL0152-1357, we find that a large relative velocity of 4800 km s{sup -1} is necessary to explain the observations. We conclude that an analysis of the morphologies of multi-frequency observations of merging clusters can be used to put meaningful constraints on the initial parameters of the progenitors.« less

Development of new S-band SLED for PAL-XFEL Linac

NASA Astrophysics Data System (ADS)

Joo, Youngdo; Park, Yongjung; Heo, Hoon; Heo, Jinyul; Park, Sung-Soo; Kim, Sang-Hee; Kim, Kwang-Hoon; Kang, Heung-Sik; Lee, Heung-Soo; Noh, Sungju; Oh, Kyoungmin

2017-01-01

In order to achieve beam acceleration to the beam energy of 10 GeV at the end of its 716 m-long linear accelerator (Linac), the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL) is going to operate the Stanford Linear Accelerator Energy Doubler (SLED) at the maximum klystron output peak power of 80 MW, with a pulse length of 4 μs, and at a repetition rate of 60 Hz. The original SLED that had been used in Pohang Light Source-II (PLS-II) can no longer sustain such a high-power operation because excessive radiation caused by RF breakdown has been frequently detected even at the lower klystron peak power during the PLS-II operation. Therefore, a new SLED is designed by modifying both the 3-dB power hybrid and the waveguide-cavity coupling structure of the original SLED where the excessive radiation has been mainly detected. The finite-difference time-domain (FDTD) simulation in the CST Microwave Studio shows that the new SLED has a peak electric field and a surface current lower than those of the original SLED at the same level of the RF input peak power, which would secure stable high-power operation. All of the 42 SLEDs in the PAL-XFEL Linac are newly fabricated and installed. During the RF conditioning of the PAL-XFEL Linac, no significant vacuum and radiation issue was found in the new SLEDs. Finally, the accelerated electron beam energy of 10 GeV obtained at the end of the PAL-XFEL Linac verified that the RF performance of the new SLED is stable.

Optimization of electrode characteristics for the Br₂/H₂ redox flow cell

DOE PAGES

Tucker, Michael C.; Cho, Kyu Taek; Weber, Adam Z.; ...

2014-10-17

The Br₂/H₂ redox flow cell shows promise as a high-power, low-cost energy storage device. The effect of various aspects of material selection, processing, and assembly of electrodes on the operation, performance, and efficiency of the system is determined. In particular, (+) electrode thickness, cell compression, hydrogen pressure, and (–) electrode architecture are investigated. Increasing hydrogen pressure and depositing the (–) catalyst layer on the membrane instead of on the carbon-paper backing layers have a large positive impact on performance, enabling a limiting current density above 2 A cm -2 and a peak power density of 1.4 W cm -2. Maximummore » energy efficiency of 79% is achieved. In addition, the root cause of limiting-current behavior in this system is elucidated, where it is found that Br - reversibly adsorbs at the Pt (–) electrode for potentials exceeding a critical value, and the extent of Br - coverage is potential-dependent. This phenomenon limits maximum cell current density and must be addressed in system modeling and design. These findings are expected to lower system cost and enable higher efficiency.« less

Floods of December 1964 and January 1965 in the Far Western States; Part 1 Description

USGS Publications Warehouse

Waananen, A.O.; Harris, D.D.; Williams, R.C.

1971-01-01

The floods of December 1964 and January 1965 in the Far Western States were extreme; in many areas, the greatest in the history of recorded streamflow and substantially greater than those of December 1955. An unusually large area--Oregon, most of Idaho, northern California, southern Washington, and small areas in western and northern Nevada--was involved. It exceeded the area flooded in 1955. Outstanding features included recordbreaking peak discharges, high sediment concentrations, large sediment loads, and extensive flood damage. The loss of 47 lives and direct property damage of more than $430 million was attributable to the floods. Yet, storage in reservoirs and operation of flood-control facilities were effective in preventing far greater damages in many areas, particularly in the Central Valley in California and the Willamette River basin in Oregon. The floods were caused by three principal storms during the period December 19 to January 31. The December 19-23 storm was the greatest in overall intensity and areal extent. Crests occurred on many major streams December 23, 1964, 9 years to the day after the great flood of December 23, 1955. The January 2-7 storm produced extreme floods in some basins in California. The January 21-31 storm produced maximum stages in some streams in northeastern Oregon and southeastern Washington and a repetition of high flows in part of the Willamette River basin and in some basins in coastal Oregon. All the storms, and particularly the warm torrential rain December 21-23, reflected the combined effect of moist unstable airmasses, strong west-southwest winds, and mountain ranges oriented nearly at right angles to the flow of air. High air temperatures and strong winds associated with the storms caused melting of snow, and the meltwater augmented the rain that fell on frozen ground. The coastal areas of northern California and southern Oregon had measurable rain on as many as 50 days in December and January. A maximum precipitation of nearly 69 inches in the 2-month period was recorded in southern Oregon, and recorded runoff at several streamflow-measurement stations indicates that greater precipitation probably occurred at higher altitudes in these areas. Flood runoff in streams, not affected by regulation, exceeded any previously recorded throughout much of the area. Some streams that had particularly notable floods are: Deep and Plush Creeks in the Great Basin ix Oregon, where the maximum flows were nearly twice those of the record floods of 1963 ; Thomes Creek, a west-side Sacramento River tributary in the Central Valley, where the maximum flow was 160 percent of the record peak of 1955; Eel, Klamath, and Smith Rivers in north-coastal California, where the catastrophic peak flows were about 1-1/3 times the floods of 1955 and the legendary winter floods of 1861-62 and inundated, damaged, or destroyed nearly all communities along the main rivers; Grande Ronde River in the lower Snake River basin, where the peak discharge at La Grande was 1.6 times the previous maximum flow during 57 years of record; John Day River in the lower Columbia River basin, where the peak discharge at the McDonald Ferry gaging station exceeded the historic peak of 1894; many Willamette River tributaries, where maximum flows exceeded previous record flows; and the Rogue River in coastal Oregon, where the maximum flow of about 500,000 cfs below the Illinois River near Agness was 86,000 cfs greater than the previous maximum in a 74-year record. The partly regulated flow of the Willamette River far exceeded that in 1955. The suspended-sediment concentration and load of most streams greatly exceeded any that had been measured previously in the flood area. In Idaho, Washington, and Oregon, the ground thaw that preceded the period of high runoff resulted in conditions conducive to severe erosion of the uplands and subsequent deposition on flooded stream terraces. The greatest concentrations of suspended sedimen

Complex crater formation: Insights from combining observations of shock pressure distribution with numerical models at the West Clearwater Lake impact structure

NASA Astrophysics Data System (ADS)

Rae, A. S. P.; Collins, G. S.; Grieve, R. A. F.; Osinski, G. R.; Morgan, J. V.

2017-07-01

Large impact structures have complex morphologies, with zones of structural uplift that can be expressed topographically as central peaks and/or peak rings internal to the crater rim. The formation of these structures requires transient strength reduction in the target material and one of the proposed mechanisms to explain this behavior is acoustic fluidization. Here, samples of shock-metamorphosed quartz-bearing lithologies at the West Clearwater Lake impact structure, Canada, are used to estimate the maximum recorded shock pressures in three dimensions across the crater. These measurements demonstrate that the currently observed distribution of shock metamorphism is strongly controlled by the formation of the structural uplift. The distribution of peak shock pressures, together with apparent crater morphology and geological observations, is compared with numerical impact simulations to constrain parameters used in the block-model implementation of acoustic fluidization. The numerical simulations produce craters that are consistent with morphological and geological observations. The results show that the regeneration of acoustic energy must be an important feature of acoustic fluidization in crater collapse, and should be included in future implementations. Based on the comparison between observational data and impact simulations, we conclude that the West Clearwater Lake structure had an original rim (final crater) diameter of 35-40 km and has since experienced up to 2 km of differential erosion.

Kinematic determinants of weapon velocity during the fencing lunge in experienced épée fencers.

PubMed

Bottoms, Lindsay; Greenhalgh, Andrew; Sinclair, Jonathan

2013-01-01

The lunge is the most common attack in fencing, however there is currently a paucity of published research investigating the kinematics of this movement. The aim of this study was to investigate if kinematics measured during the épée fencing lunge had a significant effect on sword velocity at touch and whether there were any key movement tactics that produced the maximum velocity. Lower extremity kinematic data were obtained from fourteen right handed club épée fencers using a 3D motion capture system as they completed simulated lunges. A forward stepwise multiple linear regression was performed on the data. The overall regression model yielded an Adj R2 of 0.74, p ≤ 0.01. The results show that the rear lower extremity's knee range of motion, peak hip flexion and the fore lower extremity's peak hip flexion all in the sagittal plane were significant predictors of sword velocity. The results indicate that flexion of the rear extremity's knee is an important predictor, suggesting that the fencer sits low in their stance to produce power during the lunge. Furthermore it would appear that the magnitude of peak flexion of the fore extremity's hip was a significant indicator of sword velocity suggesting movement of fore limbs should also be considered in lunge performance.

Time-temperature dependent variations in beta-carotene contents in carrot using different spectrophotometric techniques

NASA Astrophysics Data System (ADS)

Ullah, Rahat; Khan, Saranjam; Shah, Attaullah; Ali, Hina; Bilal, Muhammad

2018-05-01

The current study presents time dependent variations in the concentration of beta-carotene in carrot under different storage-temperature conditions using UV–VIS and Raman spectrophotometric techniques. The UV–VIS absorption spectra of beta-carotene extracted from carrot shows three distinct absorption peaks at 442, 467, and 500 nm with maximum absorption at 467 nm. These absorption peaks are very much reproducible and are assigned to β-carotene. Similarly, Raman spectra of carrot samples also confirmed the three main Raman peaks of beta-carotene at shift positions 1003, 1150, and 1515 cm‑1. An overall decrease in beta-carotene content has been observed for time-temperature conditions. These results depict a decrease of about 40% in the content of beta-carotene when carrot samples were stored in a refrigerator (4 °C) for the first 20 d, whereas a decrease of about 25% was observed when carrot samples were stored in a freezer (‑16 °C) for the same period. The objective of this study is to investigate the possible use of Raman spectroscopy and UV–VIS spectroscopy for quick and detailed analysis of changes (degradation) in beta-carotene content associated with time and temperature in storage (frozen foods) in order to promote quality foods for consumers. Future study with a greater focus on the concentration/content of beta-carotene in other fruits/vegetables is also desirable.

Functional morphology of prey capture in the sturgeon, Scaphirhynchus albus.

PubMed

Carroll, Andrew M; Wainwright, Peter C

2003-06-01

Acipenseriformes (sturgeon and paddlefish) are basal actinopterygians with a highly derived cranial morphology that is characterized by an anatomical independence of the jaws from the neurocranium. We examined the morphological and kinematic basis of prey capture in the Acipenseriform fish Scaphirhynchus albus, the pallid sturgeon. Feeding pallid sturgeon were filmed in lateral and ventral views and movement of cranial elements was measured from video sequences. Sturgeon feed by creating an anterior to posterior wave of cranial expansion resulting in prey movement through the mouth. The kinematics of S. albus resemble those of other aquatic vertebrates: maximum hyoid depression follows maximum gape by an average of 15 ms and maximum opercular abduction follows maximum hyoid depression by an average of 57 ms. Neurocranial rotation was not a part of prey capture kinematics in S. albus, but was observed in another sturgeon species, Acipenser medirostris. Acipenseriformes have a novel jaw protrusion mechanism, which converts rostral rotation of the hyomandibula into ventral protrusion of the jaw joint. The relationship between jaw protrusion and jaw opening in sturgeon typically resembles that of elasmobranchs, with peak upper jaw protrusion occurring after peak gape. Copyright 2003 Wiley-Liss, Inc.

[Application of the vanillin sulfuric acid colorimetry-ultraviolet spectrometry on quality evaluation of Panax notoginseng].

PubMed

Ding, Yong-Li; Wang, Yuan-Zhong; Zhang, Ji; Zhang, Qing-Zhi; Zhang, Jin-Yu; Jin, Hang

2013-02-01

In this study, Panax notoginseng samples were extracted by chloroform, ethanol and water, or by those extracted solution with 5% vanillin sulfuric acid to establish two kinds of UV fingerprint of P. notoginseng which were compared by applying the common and variation peak ratio dual index sequence analysis method and SIMCA software qualitative analysis. The results indicated that the optimization extraction time of P. notoginseng samples was 20 min with chloroform, ethanol and water extraction, but the fingerprint differed significantly after add vanillin sulfuric acid. The common peak ratios of UV fingerprint of P. notoginseng were scattered. The minimum was 25% (Y5-Y8), while the maximum was 84.38% (Y11-Y13, Y20-Y21). The maximum variation peak ratio was 177.78% (Y8-Y5), meanwhile, the variation peak ratios of several samples were more than 100%. However, the common peak ratios of UV fingerprint of P. notoginseng with vanillin sulfuric acid were concentrated (distributed in the range of 50%-70%): the minimum was 42.86%(Y1-Y19), whereas the maximum was 79.55% (Y22-Y23); the range of the variation peak ratios was also smaller with the ranges of 20%-50% in general. The result of the dual index sequence analysis was agreement with the fingerprint implied. The similarity of the UV fingerprint of the extracts of P. notoginseng after adding vanillin sulfuric acid was greater than before. Both the ages and origin was related with the difference of UV fingerprint. The similarity of the two samples with same age was more significant than those with different ages. The similarity and difference between samples was no correlation with the distance of geographic space, the near origin samples maybe have a significant similarity or difference. This method appears as good alternative for evaluate quality of the P. notoginseng and can distinguish at least two samples quantitatively, duo to it reaches the limitation of the multiple methods which only could be used to indistinctly distinguish herbs.

Optical absorption and thermally stimulated depolarization current studies of nickel chloride-doped poly(vinyl alcohol) irradiated with low-level fast neutron doses

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

Abd El-Kader, F.H.; Ibrahim, S.S.; Attia, G.

1993-11-15

The influence of neutron irradiation on ultraviolet/visible absorption and thermally stimulated depolarization current in nickel chloride-poly(vinyl alcohol) (PVA) cast films has been investigated. The spectral measurements indicate the responsibility of the Ni[sup 2][sup +] ion in its octahedral symmetry. Dopant concentrations higher than 10 wt % NiCl[sub 2] are found to make the samples more resistant to a degradation effect caused by neutron irradiation. The thermally stimulated depolarization currents (TSDC) of pure PVA revealed the existence of the glass transition T[sub g] and space charge relaxation peaks, whereas doped-PVA samples show a new sub-T[sub g] relaxation peak. A proposed mechanismmore » is introduced to account for the neutron effects on both glass transition and space charge relaxation peaks. The peak positions, peak currents, and stored charges of the sub-T[sub g] relaxation peak are strongly affected by both the concentration of the dopant and neutron exposure doses.« less

Contribution For Arc Temperature Affected By Current Increment Ratio At Peak Current In Pulsed Arc

NASA Astrophysics Data System (ADS)

Kano, Ryota; Mitubori, Hironori; Iwao, Toru

2015-11-01

Tungsten Inert Gas (TIG) Welding is one of the high quality welding. However, parameters of the pulsed arc welding are many and complicated. if the welding parameters are not appropriate, the welding pool shape becomes wide and shallow.the convection of driving force contributes to the welding pool shape. However, in the case of changing current waveform as the pulse high frequency TIG welding, the arc temperature does not follow the change of the current. Other result of the calculation, in particular, the arc temperature at the reaching time of peak current is based on these considerations. Thus, the accurate measurement of the temperature at the time is required. Therefore, the objective of this research is the elucidation of contribution for arc temperature affected by current increment ratio at peak current in pulsed arc. It should obtain a detail knowledge of the welding model in pulsed arc. The temperature in the case of increment of the peak current from the base current is measured by using spectroscopy. As a result, when the arc current increases from 100 A to 150 A at 120 ms, the transient response of the temperature didn't occur during increasing current. Thus, during the current rise, it has been verified by measuring. Therefore, the contribution for arc temperature affected by current increment ratio at peak current in pulsed arc was elucidated in order to obtain more knowledge of welding model of pulsed arc.

Pulse charging of lead-acid traction cells

NASA Technical Reports Server (NTRS)

Smithrick, J. J.

1980-01-01

Pulse charging, as a method of rapidly and efficiently charging 300 amp-hour lead-acid traction cells for an electric vehicle application was investigated. A wide range of charge pulse current square waveforms were investigated and the results were compared to constant current charging at the time averaged pulse current values. Representative pulse current waveforms were: (1) positive waveform-peak charge pulse current of 300 amperes (amps), discharge pulse-current of zero amps, and a duty cycle of about 50%; (2) Romanov waveform-peak charge pulse current of 300 amps, peak discharge pulse current of 15 amps, and a duty of 50%; and (3) McCulloch waveform peak charge pulse current of 193 amps, peak discharge pulse current of about 575 amps, and a duty cycle of 94%. Experimental results indicate that on the basis of amp-hour efficiency, pulse charging offered no significant advantage as a method of rapidly charging 300 amp-hour lead-acid traction cells when compared to constant current charging at the time average pulse current value. There were, however, some disadvantages of pulse charging in particular a decrease in charge amp-hour and energy efficiencies and an increase in cell electrolyte temperature. The constant current charge method resulted in the best energy efficiency with no significant sacrifice of charge time or amp-hour output. Whether or not pulse charging offers an advantage over constant current charging with regard to the cell charge/discharge cycle life is unknown at this time.

Monitoring the deep western boundary current in the western North Pacific by echo intensity measured with lowered acoustic Doppler current profiler

NASA Astrophysics Data System (ADS)

Komaki, Kanae; Nagano, Akira

2018-05-01

Oxidation of iron and manganese ions is predominant in the oxygen-rich deep western boundary current (DWBC) within the Pacific Ocean. By the faster removal of particulate iron hydroxide and manganese oxide, densities of the particulate matters are considered to be lower in the DWBC than the interior region. To detect the density variation of suspended particles between the DWBC and interior regions, we analyzed echo intensity (EI) measured in the western North Pacific by hydrographic casts with a 300 kHz lowered acoustic Doppler current profiler (LADCP) in a whole water column. At depths greater than 3000 m ( 3000 dbar), EI is almost uniformly low between 12°N and 30°N but peaks sharply from 30°N to 35°N to a maximum north of 35°N. EI is found to be anomalously low in the DWBC compared to the background distribution. The DWBC pathways are identifiable by the low EI and high dissolved oxygen concentration. EI data by LADCPs and other acoustic instruments may be used to observe the temporal variations of the DWBC pathways.

Combined current-modulation annealing induced enhancement of giant magnetoimpedance effect of Co-rich amorphous microwires

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

Liu, Jingshun, E-mail: jingshun-liu@163.com, E-mail: faxiang.qin@gmail.com; School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051; Qin, Faxiang, E-mail: jingshun-liu@163.com, E-mail: faxiang.qin@gmail.com

2014-05-07

We report on a combined current-modulation annealing (CCMA) method, which integrates the optimized pulsed current (PC) and DC annealing techniques, for improving the giant magnetoimpedance (GMI) effect and its field sensitivity of Co-rich amorphous microwires. Relative to an as-prepared Co{sub 68.2}Fe{sub 4.3}B{sub 15}Si{sub 12.5} wire, CCMA is shown to remarkably improve the GMI response of the wire. At 10 MHz, the maximum GMI ratio and its field sensitivity of the as-prepared wire were, respectively, increased by 3.5 and 2.28 times when subjected to CCMA. CCMA increased atomic order orientation and circumferential permeability of the wire by the co-action of high-density pulsedmore » magnetic field energy and thermal activation energy at a PC annealing stage, as well as the formation of uniform circular magnetic domains by a stable DC magnetic field at a DC annealing stage. The magnetic moment can overcome eddy-current damping or nail-sticked action in rotational magnetization, giving rise to a double-peak feature and wider working field range (up to ±2 Oe) at relatively higher frequency (f ≥ 1 MHz)« less

808nm high-power high-efficiency GaAsP/GaInP laser bars

NASA Astrophysics Data System (ADS)

Wang, Ye; Yang, Ye; Qin, Li; Wang, Chao; Yao, Di; Liu, Yun; Wang, Lijun

2008-11-01

808nm high power diode lasers, which is rapidly maturing technology technically and commercially since the introduction in 1999 of complete kilowatt-scale diode laser systems, have important applications in the fields of industry and pumping solid-state lasers (DPSSL). High power and high power conversion efficiency are extremely important in diode lasers, and they could lead to new applications where space, weight and electrical power are critical. High efficiency devices generate less waste heat, which means less strain on the cooling system and more tolerance to thermal conductivity variation, a lower junction temperature and longer lifetimes. Diode lasers with Al-free materials have superior power conversion efficiency compared with conventional AlGaAs/GaAs devices because of their lower differential series resistance and higher thermal conductivity. 808nm GaAsP/GaInP broad-waveguide emitting diode laser bars with 1mm cavity length have been fabricated. The peak power can reach to 100.9W at 106.5A at quasicontinuous wave operation (200μs, 1000Hz). The maximum power conversion efficiency is 57.38%. Based on these high power laser bars, we fabricate a 1x3 arrays, the maximum power is 64.3W in continuous wave mode when the current is 25.0A. And the threshold current is 5.9A, the slope efficiency is 3.37 W/A.

Flux focusing eddy current probe

NASA Technical Reports Server (NTRS)

Simpson, John W. (Inventor); Clendenin, C. Gerald (Inventor); Fulton, James P. (Inventor); Wincheski, Russell A. (Inventor); Todhunter, Ronald G. (Inventor); Namkung, Min (Inventor); Nath, Shridhar C. (Inventor)

1997-01-01

A flux-focusing electromagnetic sensor which uses a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks and material loss in high conductivity material. The unique feature of the device is the ferrous shield isolating a high-turn pick-up coil from an excitation coil. The use of the magnetic shield is shown to produce a null voltage output across the receiving coil in the presence of an unflawed sample. A redistribution of the current flow in the sample caused by the presence of flaws, however, eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal. The maximum sensor output is obtained when positioned symmetrically above the crack. Hence, by obtaining the position of the maximum sensor output, it is possible to track the fault and locate the area surrounding its tip. The accuracy of tip location is enhanced by two unique features of the sensor; a very high signal-to-noise ratio of the probe's output which results in an extremely smooth signal peak across the fault, and a rapidly decaying sensor output outside a small area surrounding the crack tip which enables the region for searching to be clearly defined. Under low frequency operation, material thinning due to corrosion damage causes an incomplete shielding of the pick-up coil. The low frequency output voltage of the probe is therefore a direct indicator of the thickness of the test sample.

Lightning Attachment to Wind Turbines in Central Kansas: Video Observations, Correlation with the NLDN and in-situ Peak Current Measurements

NASA Astrophysics Data System (ADS)

Myers, J.; Cummins, K. L.; Hutchinson, M.; Nag, A.

2012-12-01

Lightning attachment to tall objects has been studied for decades. The attachment of lightning to electric power transmission towers in elevated terrain has driven much of the quantitative assessment of lightning characteristics in the 1970's and 80's. This has led to the understanding that in flat terrain, the probability of upward-initiated lightning is negligible for tower heights less than 100 m. For tower heights greater than 100, the probability increases roughly linearly with the log of height, reaching 100% at a height of 400 m. Additionally, the probability of upward initiation increases when the object resides on locally-elevated terrain. Over the last decade, there has been renewed interest in the study of lightning attachment to tall objects in general, and wind turbines in particular, following the establishment of large "wind farms" in lightning-prone regions. In this study, we present video observations, radiation magnetic field, and in-situ peak current measurements of lightning from an ongoing field program in a large wind farm in north-central Kansas, located in the U.S. Central Great Plains. The terrain variations within the wind farm are small rolling hills with peak variations on the order of 25 m. All turbines had a turbine hub height of 80 m, and a blade tip maximum height of 125 m. Two digital video camera systems (60 fields-per-second) were configured to self-trigger 2-second video sequences using a sequential-field-subtraction scene analysis (ufo-Capture). The two cameras had a common field of view that included 8 of the wind turbines. Nearby NLDN sensors were configured to record information that allows reconstruction of magnetic field waveforms within the bandwidth of the NLDN sensors. Some of the turbines were equipped with semi-quantitative in-situ peak current measuring devices. To date, more than 100 cloud-to-ground (CG) flashes have terminated within the perimeter of the wind farm. Video observations of flashes that attached to turbines (all to turbine blades) include five natural (downward leader) flashes and two "upward flashes" (fully developed upward leaders lasting 10's of milliseconds). Both upward flashes appear to have been triggered by nearby positive CG flashes, resulting in upward (presumably positive) leaders. Selected video observations in conjunction with NLDN data and waveform measurements, and in situ current measurements obtained during this campaign, will be presented and discussed in the context of storm characteristics. Differences with previous findings for fixed towers (no rotating blades) will also be discussed.

Direct current performance and current collapse in AlGaN/GaN insulated gate high-electron mobility transistors on Si (1 1 1) substrate with very thin SiO2 gate dielectric

NASA Astrophysics Data System (ADS)

Lachab, M.; Sultana, M.; Fatima, H.; Adivarahan, V.; Fareed, Q.; Khan, M. A.

2012-12-01

This work reports on the dc performance of AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) grown on Si (1 1 1) substrate and the study of current dispersion in these devices using various widely adopted methods. The MOSHEMTs were fabricated using a very thin (4.2 nm) SiO2 film as the gate insulator and were subsequently passivated with about 30 nm thick Si3N4 layer. For devices with 2.5 µm long gates and a 4 µm drain-to-source spacing, the maximum saturation drain current density was 822 mA mm-1 at + 4 V gate bias and the peak external transconductance was ˜100 mS mm-1. Furthermore, the oxide layer successfully suppressed the drain and gate leakage currents with the subthreshold current and the gate diode current levels exceeding by more than three orders of magnitude the levels found in their Schottky gate counterparts. Capacitance-voltage and dynamic current-voltage measurements were carried out to assess the oxide quality as well as the devices’ surface properties after passivation. The efficacy of each of these characterization techniques to probe the presence of interface traps and oxide charge in the nitride-based transistors is also discussed.

InP tunnel junction for InGaAs/InP tandem solar cells

NASA Technical Reports Server (NTRS)

Vilela, M. F.; Freundlich, A.; Bensaoula, A.; Medelci, N.; Renaud, P.

1995-01-01

Chemical beam epitaxy (CBE) has been shown to allow the growth of high quality materials with reproducible complex compositional and doping profiles. The main advantage of CBE compared to metalorganic chemical vapor deposition (MOCVD), the most popular technique for InP-based photovoltaic device fabrication, is the ability to grow high purity epilayers at much lower temperatures (450-530 C). We have previously shown that CBE is perfectly suited toward the fabrication of complex photovoltaic devices such as InP/InGaAs monolithically integrated tandem solar cells, because its low process temperature preserves the electrical characteristics of the InGaAs tunnel junction commonly used as an ohmic interconnect. In this work using CBE for the fabrication of optically transparent (with respect to the bottom cell) InP tunnel diodes is demonstrated. Epitaxial growth were performed in a Riber CBE 32 system using PH3 and TMIn as III and V precursors. Solid Be (p-type) and Si (n-type) have been used as doping sources, allowing doping levels up to 2 x 10(exp -19)/cu cm and 1 x 10(exp -19)/cu cm for n and p type respectively. The InP tunnel junction characteristics and the influence of the growth's conditions (temperature, growth rate) over its performance have been carefully investigated. InP p(++)/n(++) tunnel junction with peak current densities up to 1600 A/sq cm and maximum specific resistivities (V(sub p)/I(sub p) - peak voltage to peak current ratio) in the range of 10(exp -4) Omega-sq cm were obtained. The obtained peak current densities exceed the highest results previously reported for their lattice matched counterparts, In(0.53)Ga( 0.47)As and should allow the realization of improved minimal absorption losses in the interconnect InP/InGaAs tandem devices for Space applications. Owing to the low process temperature required for the top cell, these devices exhibit almost no degradation of its characteristics after the growth of subsequent thick InP layer suggesting minimal doping cross diffusion in the narrow space-charge region (approximately 1-5 nm) of the device. The fabrication of tandem devices using InP tunnel diodes as interconnect is in progress and will be reported at the conference.

Observed and modeled tsunami current velocities in Humboldt Bay and Crescent City Harbor, northern California

NASA Astrophysics Data System (ADS)

Admire, A. R.; Dengler, L.; Crawford, G. B.; uslu, B. U.; Montoya, J.

2012-12-01

A pilot project was initiated in 2009 in Humboldt Bay, about 370 kilometers (km) north of San Francisco, California, to measure the currents produced by tsunamis. Northern California is susceptible to both near- and far-field tsunamis and has a historic record of damaging events. Crescent City Harbor, located approximately 100 km north of Humboldt Bay, suffered US 20 million in damages from strong currents produced by the 2006 Kuril Islands tsunami and an additional US 20 million from the 2011 Japan tsunami. In order to better evaluate these currents in northern California, we deployed a Nortek Aquadopp 600kHz 2D Acoustic Doppler Current Profiler (ADCP) with a one-minute sampling interval in Humboldt Bay, near the existing National Oceanic and Atmospheric Administration (NOAA) National Ocean Service (NOS) tide gauge station. The instrument recorded the tsunamis produced by the Mw 8.8 Chile earthquake on February 27, 2010 and the Mw 9.0 Japan earthquake on March 11, 2011. Currents from the 2010 tsunami persisted in Humboldt Bay for at least 30 hours with peak amplitudes of about 0.3 meters per second (m/s). The 2011 tsunami signal lasted for over 86 hours with peak amplitude of 0.95 m/s. Strongest currents corresponded to the maximum change in water level as recorded on the NOAA NOS tide gauge, and occurred 90 minutes after the initial wave arrival. No damage was observed in Humboldt Bay for either event. In Crescent City, currents for the first three and a half hours of the 2011 Japan tsunami were estimated using security camera video footage from the Harbor Master building across from the entrance to the small boat basin, approximately 70 meters away from the NOAA NOS tide gauge station. The largest amplitude tide gauge water-level oscillations and most of the damage occurred within this time window. The currents reached a velocity of approximately 4.5 m/s and six cycles exceeded 3 m/s during this period. Measured current velocities both in Humboldt Bay and in Crescent City were compared to calculated velocities from the Method of Splitting Tsunamis (MOST) numerical model. For Humboldt Bay, the 2010 model tsunami frequencies matched the actual values for the first two hours after the initial arrival however the amplitudes were underestimated by approximately 65%. MOST replicated the first four hours of the 2011 tsunami signal in Humboldt Bay quite well although the peak flood currents were underestimated by about 50%. MOST predicted attenuation of the signal after four hours but the actual signal persisted at a nearly constant level for more than 48 hours. In Crescent City, the model prediction of the 2011 frequency agreed quite well with the observed signal for the first two and a half hours after the initial arrival with a 50% underestimation of the peak amplitude. The results from this project demonstrate that ADCPs can effectively record tsunami currents for small to moderate events and can be used to calibrate and validate models (i.e. MOST) in order to better predict hazardous tsunami conditions and improve planned responses to protect lives and property, especially within harbors. An ADCP will be installed in Crescent City Harbor and four additional ADCPs are being deployed in Humboldt Bay during the fall of 2012.

Onset and duration of intravenous and intraosseous rocuronium in hypovolemic swine.

PubMed

Nemeth, Miguel; Williams, George N; Prichard, Debbie; McConnico, Angie; Johnson, Don; Loughren, Michael

2016-01-01

Compare the onset and duration of rocuronium administered via the intravenous (IV), and intraosseous (IO) routes in a hypovolemic swine model. Prospective, between subjects, experimental study. Vivarium. Yorkshire-cross swine (N = 8). Electromyography (EMG) amplitudes were recorded at baseline and for every 15 seconds after administering 1.2 mg/kg of rocuronium via IV or IO routes to hypovolemic swine. EMG amplitudes were measured until termination of EMG activity and then measured every 5 minutes until there was a return to baseline values. Individual data were transformed to percent baseline. The time from the end of injection to 90 percent reduction of baseline EMG activity (Onset 90 ), the time to maximum reduction (Onset peak ), and the maximum reduction of the neuromuscular response (peak effect), as well as, time from the end of injection to the return of 25, 50, 75, and 95 percent of baseline EMG activity was used to characterize onset and recovery of neuromuscular function. Maximum reduction, Onset 90 and Onset peak times were not statistically different between groups. The IV group's mean time to recovery of all benchmarks was faster than the IO group. The IO group took statistically longer than the IV group to return to 25, 50, 75, and 95 percent of baseline activity. The IO route is an effective method of administering rocuronium and is comparable to the IV route even under conditions of significant hemorrhage.

Analysis of read-out heating rate effects on the glow peaks of TLD-100 using WinGCF software

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

Bauk, Sabar, E-mail: sabar@usm.my; Hussin, Siti Fatimah; Alam, Md. Shah

This study was done to analyze the effects of the read-out heating rate on the LiF:Mg,Ti (TLD-100) thermoluminescent dosimeters (TLD) glow peaks using WinGCF computer software. The TLDs were exposed to X-ray photons with a potential difference of 72 kVp and 200 mAs in air and were read-out using a Harshaw 3500 TLD reader. The TLDs were read-out using four read-out heating rates at 10, 7, 4 and 1 °C s{sup −1}. It was observed that lowering the heating rate could separate more glow peaks. The activation energy for peak 5 was found to be lower than that for peakmore » 4. The peak maximum temperature and the integral value of the main peak decreased as the heating rate decreases.« less

Coil optimisation for transcranial magnetic stimulation in realistic head geometry.

PubMed

Koponen, Lari M; Nieminen, Jaakko O; Mutanen, Tuomas P; Stenroos, Matti; Ilmoniemi, Risto J

Transcranial magnetic stimulation (TMS) allows focal, non-invasive stimulation of the cortex. A TMS pulse is inherently weakly coupled to the cortex; thus, magnetic stimulation requires both high current and high voltage to reach sufficient intensity. These requirements limit, for example, the maximum repetition rate and the maximum number of consecutive pulses with the same coil due to the rise of its temperature. To develop methods to optimise, design, and manufacture energy-efficient TMS coils in realistic head geometry with an arbitrary overall coil shape. We derive a semi-analytical integration scheme for computing the magnetic field energy of an arbitrary surface current distribution, compute the electric field induced by this distribution with a boundary element method, and optimise a TMS coil for focal stimulation. Additionally, we introduce a method for manufacturing such a coil by using Litz wire and a coil former machined from polyvinyl chloride. We designed, manufactured, and validated an optimised TMS coil and applied it to brain stimulation. Our simulations indicate that this coil requires less than half the power of a commercial figure-of-eight coil, with a 41% reduction due to the optimised winding geometry and a partial contribution due to our thinner coil former and reduced conductor height. With the optimised coil, the resting motor threshold of abductor pollicis brevis was reached with the capacitor voltage below 600 V and peak current below 3000 A. The described method allows designing practical TMS coils that have considerably higher efficiency than conventional figure-of-eight coils. Copyright © 2017 Elsevier Inc. All rights reserved.

Eddy Current Method for Fatigue Testing

NASA Technical Reports Server (NTRS)

Simpson, John W. (Inventor); Fulton, James P. (Inventor); Wincheski, Russell A. (Inventor); Todhunter, Ronald G. (Inventor); Namkung, Min (Inventor); Nath, Shridhar C. (Inventor)

1997-01-01

Flux-focusing electromagnetic sensor using a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks and material loss in high conductivity material. A ferrous shield isolates a high-turn pick-up coil from an excitation coil. Use of the magnetic shield produces a null voltage output across the receiving coil in presence of an unflawed sample. Redistribution of the current flow in the sample caused by the presence of flaws. eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal. Maximum sensor output is obtained when positioned symmetrically above the crack. By obtaining position of maximum sensor output, it is possible to track the fault and locate the area surrounding its tip. Accuracy of tip location is enhanced by two unique features of the sensor; a very high signal-to-noise ratio of the probe's output resulting in an extremely smooth signal peak across the fault, and a rapidly decaying sensor output outside a small area surrounding the crack tip enabling the search region to be clearly defined. Under low frequency operation, material thinning due to corrosion causes incomplete shielding of the pick-up coil. Low frequency output voltage of the probe is therefore a direct indicator of thickness of the test sample. Fatigue testing a conductive material is accomplished by applying load to the material, applying current to the sensor, scanning the material with the sensor, monitoring the sensor output signal, adjusting material load based on the sensor output signal of the sensor, and adjusting position of the sensor based on its output signal.

PeakWorks

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

2016-11-30

The PeakWorks software is designed to assist in the quantitative analysis of atom probe tomography (APT) generated mass spectra. Specifically, through an interactive user interface, mass peaks can be identified automatically (defined by a threshold) and/or identified manually. The software then provides a means to assign specific elemental isotopes (including more than one) to each peak. The software also provides a means for the user to choose background subtraction of each peak based on background fitting functions, the choice of which is left to the users discretion. Peak ranging (the mass range over which peaks are integrated) is also automatedmore » allowing the user to chose a quantitative range (e.g. full-widthhalf- maximum). The software then integrates all identified peaks, providing a background-subtracted composition, which also includes the deconvolution of peaks (i.e. those peaks that happen to have overlapping isotopic masses). The software is also able to output a 'range file' that can be used in other software packages, such as within IVAS. A range file lists the peak identities, the mass range of each identified peak, and a color code for the peak. The software is also able to generate 'dummy' peak ranges within an outputted range file that can be used within IVAS to provide a means for background subtracted proximity histogram analysis.« less

Increasing the Life of a Xenon-Ion Spacecraft Thruster

NASA Technical Reports Server (NTRS)

Goebel, Dan; Polk, James; Sengupta, Anita; Wirz, Richard

2007-01-01

A short document summarizes the redesign of a xenon-ion spacecraft thruster to increase its operational lifetime beyond a limit heretofore imposed by nonuniform ion-impact erosion of an accelerator electrode grid. A peak in the ion current density on the centerline of the thruster causes increased erosion in the center of the grid. The ion-current density in the NSTAR thruster that was the subject of this investigation was characterized by peak-to-average ratio of 2:1 and a peak-to-edge ratio of greater than 10:1. The redesign was directed toward distributing the same beam current more evenly over the entire grid andinvolved several modifications of the magnetic- field topography in the thruster to obtain more nearly uniform ionization. The net result of the redesign was to reduce the peak ion current density by nearly a factor of two, thereby halving the peak erosion rate and doubling the life of the thruster.

Analysis and Assessment of Peak Lightning Current Probabilities at the NASA Kennedy Space Center

NASA Technical Reports Server (NTRS)

Johnson, D. L.; Vaughan, W. W.

1999-01-01

This technical memorandum presents a summary by the Electromagnetics and Aerospace Environments Branch at the Marshall Space Flight Center of lightning characteristics and lightning criteria for the protection of aerospace vehicles. Probability estimates are included for certain lightning strikes (peak currents of 200, 100, and 50 kA) applicable to the National Aeronautics and Space Administration Space Shuttle at the Kennedy Space Center, Florida, during rollout, on-pad, and boost/launch phases. Results of an extensive literature search to compile information on this subject are presented in order to answer key questions posed by the Space Shuttle Program Office at the Johnson Space Center concerning peak lightning current probabilities if a vehicle is hit by a lightning cloud-to-ground stroke. Vehicle-triggered lightning probability estimates for the aforementioned peak currents are still being worked. Section 4.5, however, does provide some insight on estimating these same peaks.

High Mid-Flow to Vital Capacity Ratio and the Response to Exercise in Children With Congenital Heart Disease.

PubMed

Vilozni, Daphna; Alcaneses-Ofek, Maria Rosario; Reuveny, Ronen; Rosenblum, Omer; Inbar, Omri; Katz, Uriel; Ziv-Baran, Tomer; Dubnov-Raz, Gal

2016-12-01

Pulmonary mechanics may play a role in exercise intolerance in patients with congenital heart disease (CHD). A reduced FVC volume could increase the ratio between mid-flow (FEF 25-75% ) and FVC, which is termed high dysanapsis. The relationship between high dysanapsis and the response to maximum-intensity exercise in children with CHD had not yet been studied. The aim of this work was to examine whether high dysanapsis is related to the cardiopulmonary response to maximum-intensity exercise in pediatric subjects with CHD. We retrospectively collected data from 42 children and adolescents with CHD who had either high dysanapsis (ratio >1.2; n = 21) or normal dysanapsis (control) (n = 21) as measured by spirometry. Data extracted from cardiopulmonary exercise test reports included peak values of heart rate, work load, V̇ O 2 , V̇ CO 2 , and ventilation parameters and submaximum values, including ventilatory threshold and ventilatory equivalents. There were no significant differences in demographic and clinical parameters between the groups. Participants with high dysanapsis differed from controls in lower median peak oxygen consumption (65.8% vs 83.0% of predicted, P = .02), peak oxygen pulse (78.6% vs 87.8% of predicted, P = .02), ventilatory threshold (73.8% vs 85.3% of predicted, P = .03), and maximum breathing frequency (106% vs 121% of predicted, P = .035). In the high dysanapsis group only, median peak ventilation and tidal volume were significantly lower than 80% of predicted values. In children and adolescents with corrected CHD, high dysanapsis was associated with a lower ventilatory capacity and reduced aerobic fitness, which may indicate respiratory muscle impairments. Copyright © 2016 by Daedalus Enterprises.

Cardiorespiratory functional assessment after pediatric heart transplantation.

PubMed

Pastore, E; Turchetta, A; Attias, L; Calzolari, A; Giordano, U; Squitieri, C; Parisi, F

2001-12-01

Limited data are available on the exercise capacity of young heart transplant recipients. The aim of this study was therefore to assess cardiorespiratory responses to exercise in this group of patients. Fourteen consecutive heart transplant recipients (six girls and eight boys, age-range 5-15 yr) and 14 healthy matched controls underwent a Bruce treadmill test to determine: duration of test; resting and maximum heart rates; maximum systolic blood pressure; peak oxygen consumption (VO2 peak); and cardiac output. Duration of test and heart rate increase were then compared with: time since transplantation, rejections per year, and immunosuppressive drugs received. The recipients also underwent the following lung function tests: forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). When compared with healthy controls, transplant recipients had tachycardia at rest (126 +/- 3.7 beats/min; p < 0.001); significantly reduced tolerance (9.3 +/- 0.4 min; p < 0.001), a maximum heart rate of 169 +/- 5.4 beats/min (p < 0.05); a cardiac output of 5.65 +/- 0.6 L/min (p < 0.05); and a lower heart-rate increase from rest to peak exercise (p < 0.001) but a similar VO2 peak. The heart-rate increase correlated significantly with time post-transplant (r = 0.55; p < 0.05), number of rejection episodes per year (r = - 0.63; p < 0.05), and number of immunosuppressive drugs (r = - 0.60; p < 0.05). The recipients had normal FVC and FEV1 values. After surgery, few heart transplant recipients undertake physical activity, possibly owing to over-protective parents and teachers and to a lack of suitable supervised facilities. The authors stress the importance of a cardiorespiratory functional evaluation for assessment of health status and to encourage recipients, if possible, to undertake regular physical activity.

Analysis on the time and frequency domains of the acceleration in front crawl stroke.

PubMed

Gil, Joaquín Madera; Moreno, Luis-Millán González; Mahiques, Juan Benavent; Muñoz, Víctor Tella

2012-05-01

The swimming involves accelerations and decelerations in the swimmer's body. Thus, the main objective of this study is to make a temporal and frequency analysis of the acceleration in front crawl swimming, regarding the gender and the performance. The sample was composed by 31 male swimmers (15 of high-level and 16 of low-level) and 20 female swimmers (11 of high-level and 9 of low-level). The acceleration was registered from the third complete cycle during eight seconds in a 25 meters maximum velocity test. A position transducer (200Hz) was used to collect the data, and it was synchronized to an aquatic camera (25Hz). The acceleration in the temporal (root mean square, minimum and maximum of the acceleration) and frequency (power peak, power peak frequency and spectral area) domains was calculated with Fourier analysis, as well as the velocity and the spectrums distribution in function to present one or more main peaks (type 1 and type 2). A one-way ANOVA was used to establish differences between gender and performance. Results show differences between genders in all the temporal domain variables (p<0.05) and only the Spectral Area (SA) in the frequency domain (p<0.05). Between gender and performance, only the Root Mean Square (RMS) showed differences in the performance of the male swimmers (p<0.05) and in the higher level swimmers, the Maximum (Max) and the Power Peak (PP) of the acceleration showed differences between both genders (p<0.05). These results confirms the importance of knowing the RMS to determine the efficiency of the swimmers regarding gender and performance level.

High methane natural gas/air explosion characteristics in confined vessel.

PubMed

Tang, Chenglong; Zhang, Shuang; Si, Zhanbo; Huang, Zuohua; Zhang, Kongming; Jin, Zebing

2014-08-15

The explosion characteristics of high methane fraction natural gas were investigated in a constant volume combustion vessel at different initial conditions. Results show that with the increase of initial pressure, the peak explosion pressure, the maximum rate of pressure rise increase due to a higher amount (mass) of flammable mixture, which delivers an increased amount of heat. The increased total flame duration and flame development time result as a consequence of the higher amount of flammable mixture. With the increase of the initial temperature, the peak explosion pressures decrease, but the pressure increase during combustion is accelerated, which indicates a faster flame speed and heat release rate. The maximum value of the explosion pressure, the maximum rate of pressure rise, the minimum total combustion duration and the minimum flame development time is observed when the equivalence ratio of the mixture is 1.1. Additionally, for higher methane fraction natural gas, the explosion pressure and the maximum rate of pressure rise are slightly decreased, while the combustion duration is postponed. The combustion phasing is empirically correlated with the experimental parameters with good fitting performance. Furthermore, the addition of dilute gas significantly reduces the explosion pressure, the maximum rate of pressure rise and postpones the flame development and this flame retarding effect of carbon dioxide is stronger than that of nitrogen. Copyright © 2014 Elsevier B.V. All rights reserved.

Assessing women's lacrosse head impacts using finite element modelling.

PubMed

Clark, J Michio; Hoshizaki, T Blaine; Gilchrist, Michael D

2018-04-01

Recently studies have assessed the ability of helmets to reduce peak linear and rotational acceleration for women's lacrosse head impacts. However, such measures have had low correlation with injury. Maximum principal strain interprets loading curves which provide better injury prediction than peak linear and rotational acceleration, especially in compliant situations which create low magnitude accelerations but long impact durations. The purpose of this study was to assess head and helmet impacts in women's lacrosse using finite element modelling. Linear and rotational acceleration loading curves from women's lacrosse impacts to a helmeted and an unhelmeted Hybrid III headform were input into the University College Dublin Brain Trauma Model. The finite element model was used to calculate maximum principal strain in the cerebrum. The results demonstrated for unhelmeted impacts, falls and ball impacts produce higher maximum principal strain values than stick and shoulder collisions. The strain values for falls and ball impacts were found to be within the range of concussion and traumatic brain injury. The results also showed that men's lacrosse helmets reduced maximum principal strain for follow-through slashing, falls and ball impacts. These findings are novel and demonstrate that for high risk events, maximum principal strain can be reduced by implementing the use of helmets if the rules of the sport do not effectively manage such situations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Oceanic Lightning versus Continental Lightning: VLF Peak Current Discrepancies

NASA Astrophysics Data System (ADS)

Dupree, N. A., Jr.; Moore, R. C.

2015-12-01

Recent analysis of the Vaisala global lightning data set GLD360 suggests that oceanic lightning tends to exhibit larger peak currents than continental lightning (lightning occurring over land). The GLD360 peak current measurement is derived from distant measurements of the electromagnetic fields emanated during the lightning flash. Because the GLD360 peak current measurement is a derived quantity, it is not clear whether the actual peak currents of oceanic lightning tend to be larger, or whether the resulting electromagnetic field strengths tend to be larger. In this paper, we present simulations of VLF signal propagation in the Earth-ionosphere waveguide to demonstrate that the peak field values for oceanic lightning can be significantly stronger than for continental lightning. Modeling simulations are performed using the Long Wave Propagation Capability (LWPC) code to directly evaluate the effect of ground conductivity on VLF signal propagation in the 5-15 kHz band. LWPC is an inherently narrowband propagation code that has been modified to predict the broadband response of the Earth-Ionosphere waveguide to an impulsive lightning flash while preserving the ability of LWPC to account for an inhomogeneous waveguide. Furthermore, we evaluate the effect of return stroke speed on these results.

Analysis of flood-magnitude and flood-frequency data for streamflow-gaging stations in the Delaware and North Branch Susquehanna River Basins in Pennsylvania

USGS Publications Warehouse

Roland, Mark A.; Stuckey, Marla H.

2007-01-01

The Delaware and North Branch Susquehanna River Basins in Pennsylvania experienced severe flooding as a result of intense rainfall during June 2006. The height of the flood waters on the rivers and tributaries approached or exceeded the peak of record at many locations. Updated flood-magnitude and flood-frequency data for streamflow-gaging stations on tributaries in the Delaware and North Branch Susquehanna River Basins were analyzed using data through the 2006 water year to determine if there were any major differences in the flood-discharge data. Flood frequencies for return intervals of 2, 5, 10, 50, 100, and 500 years (Q2, Q5, Q10, Q50, Q100, and Q500) were determined from annual maximum series (AMS) data from continuous-record gaging stations (stations) and were compared to flood discharges obtained from previously published Flood Insurance Studies (FIS) and to flood frequencies using partial-duration series (PDS) data. A Wilcoxon signed-rank test was performed to determine any statistically significant differences between flood frequencies computed from updated AMS station data and those obtained from FIS. Percentage differences between flood frequencies computed from updated AMS station data and those obtained from FIS also were determined for the 10, 50, 100, and 500 return intervals. A Mann-Kendall trend test was performed to determine statistically significant trends in the updated AMS peak-flow data for the period of record at the 41 stations. In addition to AMS station data, PDS data were used to determine flood-frequency discharges. The AMS and PDS flood-frequency data were compared to determine any differences between the two data sets. An analysis also was performed on AMS-derived flood frequencies for four stations to evaluate the possible effects of flood-control reservoirs on peak flows. Additionally, flood frequencies for three stations were evaluated to determine possible effects of urbanization on peak flows. The results of the Wilcoxon signed-rank test showed a significant difference at the 95-percent confidence level between the Q100 computed from AMS station data and the Q100 determined from previously published FIS for 97 sites. The flood-frequency discharges computed from AMS station data were consistently larger than the flood discharges from the FIS; mean percentage difference between the two data sets ranged from 14 percent for the Q100 to 20 percent for the Q50. The results of the Mann-Kendall test showed that 8 stations exhibited a positive trend (i.e., increasing annual maximum peaks over time) over their respective periods of record at the 95-percent confidence level, and an additional 7 stations indicated a positive trend, for a total of 15 stations, at a confidence level of greater than or equal to 90 percent. The Q2, Q5, Q10, Q50, and Q100 determined from AMS and PDS data for each station were compared by percentage. The flood magnitudes for the 2-year return period were 16 percent higher when partial-duration peaks were incorporated into the analyses, as opposed to using only the annual maximum peaks. The discharges then tended to converge around the 5-year return period, with a mean collective difference of only 1 percent. At the 10-, 50-, and 100-year return periods, the flood magnitudes based on annual maximum peaks were, on average, 6 percent higher compared to corresponding flood magnitudes based on partial-duration peaks. Possible effects on flood peaks from flood-control reservoirs and urban development within the basin also were examined. Annual maximum peak-flow data from four stations were divided into pre- and post-regulation periods. Comparisons were made between the Q100 determined from AMS station data for the periods of record pre- and post-regulation. Two stations showed a nearly 60- and 20-percent reduction in the 100-year discharges; the other two stations showed negligible differences in discharges. Three stations within urban basins were compared to 38 stations

Optically controlled resonant tunneling in a double-barrier diode

NASA Astrophysics Data System (ADS)

Kan, S. C.; Wu, S.; Sanders, S.; Griffel, G.; Yariv, A.

1991-03-01

The resonant tunneling effect is optically enhanced in a GaAs/GaAlAs double-barrier structure that has partial lateral current confinement. The peak current increases and the valley current decreases simultaneously when the device surface is illuminated, due to the increased conductivity of the top layer of the structure. The effect of the lateral current confinement on the current-voltage characteristic of a double-barrier resonant tunneling structure was also studied. With increased lateral current confinement, the peak and valley current decrease at a different rate such that the current peak-to-valley ratio increases up to three times. The experimental results are explained by solving the electrostatic potential distribution in the structure using a simple three-layer model.

TRPV3 channels mediate strontium-induced mouse egg activation

PubMed Central

Carvacho, Ingrid; Lee, Hoi Chang; Fissore, Rafael A.; Clapham, David E.

2014-01-01

SUMMARY In mammals, calcium influx is required for oocyte maturation and egg activation. The molecular identities of the calcium-permeant channels that underlie the initiation of embryonic development are not established. Here, we describe a Transient Receptor Potential (TRP) ion channel current activated by TRP agonists that is absent in TrpV3−/− eggs. TRPV3 current is differentially expressed during oocyte maturation, reaching a peak of maximum density and activity at metaphase of meiosis II (MII), the stage of fertilization. Selective activation of TRPV3 channels provokes egg activation by mediating massive calcium entry. Widely used to activate eggs, strontium application is known to yield normal offspring in combination with somatic cell nuclear transfer. We show that TRPV3 is required for strontium influx, as TrpV3−/− eggs failed to permeate Sr2+ or undergo strontium-induced activation. We propose that TRPV3 is the major mediator of calcium influx in mouse eggs and is a putative target for artificial egg activation. PMID:24316078

DNA bases thymine and adenine in bio-organic light emitting diodes.

PubMed

Gomez, Eliot F; Venkatraman, Vishak; Grote, James G; Steckl, Andrew J

2014-11-24

We report on the use of nucleic acid bases (NBs) in organic light emitting diodes (OLEDs). NBs are small molecules that are the basic building blocks of the larger DNA polymer. NBs readily thermally evaporate and integrate well into the vacuum deposited OLED fabrication. Adenine (A) and thymine (T) were deposited as electron-blocking/hole-transport layers (EBL/HTL) that resulted in increases in performance over the reference OLED containing the standard EBL material NPB. A-based OLEDs reached a peak current efficiency and luminance performance of 48 cd/A and 93,000 cd/m(2), respectively, while T-based OLEDs had a maximum of 76 cd/A and 132,000 cd/m(2). By comparison, the reference OLED yielded 37 cd/A and 113,000 cd/m(2). The enhanced performance of T-based devices is attributed to a combination of energy levels and structured surface morphology that causes more efficient and controlled hole current transport to the emitting layer.

Combined Ceria Reduction and Methane Reforming in a Solar-Driven Particle-Transport Reactor.

PubMed

Welte, Michael; Warren, Kent; Scheffe, Jonathan R; Steinfeld, Aldo

2017-09-20

We report on the experimental performance of a solar aerosol reactor for carrying out the combined thermochemical reduction of CeO 2 and reforming of CH 4 using concentrated radiation as the source of process heat. The 2 kW th solar reactor prototype utilizes a cavity receiver enclosing a vertical Al 2 O 3 tube which contains a downward gravity-driven particle flow of ceria particles, either co-current or counter-current to a CH 4 flow. Experimentation under a peak radiative flux of 2264 suns yielded methane conversions up to 89% at 1300 °C for residence times under 1 s. The maximum extent of ceria reduction, given by the nonstoichiometry δ (CeO 2-δ ), was 0.25. The solar-to-fuel energy conversion efficiency reached 12%. The syngas produced had a H 2 :CO molar ratio of 2, and its calorific value was solar-upgraded by 24% over that of the CH 4 reformed.

Combined Ceria Reduction and Methane Reforming in a Solar-Driven Particle-Transport Reactor

PubMed Central

2017-01-01

We report on the experimental performance of a solar aerosol reactor for carrying out the combined thermochemical reduction of CeO2 and reforming of CH4 using concentrated radiation as the source of process heat. The 2 kWth solar reactor prototype utilizes a cavity receiver enclosing a vertical Al2O3 tube which contains a downward gravity-driven particle flow of ceria particles, either co-current or counter-current to a CH4 flow. Experimentation under a peak radiative flux of 2264 suns yielded methane conversions up to 89% at 1300 °C for residence times under 1 s. The maximum extent of ceria reduction, given by the nonstoichiometry δ (CeO2−δ), was 0.25. The solar-to-fuel energy conversion efficiency reached 12%. The syngas produced had a H2:CO molar ratio of 2, and its calorific value was solar-upgraded by 24% over that of the CH4 reformed. PMID:28966440

GaSb superluminescent diodes with broadband emission at 2.55 μm

NASA Astrophysics Data System (ADS)

Zia, Nouman; Viheriälä, Jukka; Koivusalo, Eero; Virtanen, Heikki; Aho, Antti; Suomalainen, Soile; Guina, Mircea

2018-01-01

We report the development of superluminescent diodes (SLDs) emitting mW-level output power in a broad spectrum centered at a wavelength of 2.55 μm. The emitting structure consists of two compressively strained GaInAsSb/GaSb-quantum wells placed within a lattice-matched AlGaAsSb waveguide. An average output power of more than 3 mW and a peak power of 38 mW are demonstrated at room temperature under pulsed operation. A cavity suppression element is used to prevent lasing at high current injection allowing emission in a broad spectrum with a full width at half maximum (FWHM) of 124 nm. The measured far-field of the SLD confirms a good beam quality at different currents. These devices open further development possibilities in the field of spectroscopy, enabling, for example, detection of complex molecules and mixtures of gases that manifest a complex absorption spectrum over a broad spectral range.

Tide-related variability of TAG hydrothermal activity observed by deep-sea monitoring system and OBSH

NASA Astrophysics Data System (ADS)

Fujioka, Kantaro; Kobayashi, Kazuo; Kato, Kazuhiro; Aoki, Misumi; Mitsuzawa, Kyohiko; Kinoshita, Masataka; Nishizawa, Azusa

1997-12-01

Hydrothermal activities were monitored by an ocean bottom seismometer with hydrophone (OBSH) and a composite measuring system (Manatee) including CTD, current meter, transmission meter and cameras at a small depression on the TAG hydrothermal mound in the Mid-Atlantic Ridge. Low-frequency pressure pulses detected by the hydrophone with semi-diurnal periodicity seem to correspond to cycles of hydrothermal upflow from a small and short-lived smoker vent close to the observing site. The peaks of pressure pulses are synchronous with the maximum gradient of areal strain decrease due to tidal load release. Microearthquakes with very near epicenters occur sporadically and do not appear to be directly correlatable to hydrothermal venting. Temporal variations in bottom water temperature also have semi-diurnal periodicity but are more complicated than the pressure events. Temperatures may be affected both by upwelling of hot water and by lateral flow of the bottom current changing its directions with ocean tide.

Current-wave spectra coupling project. Volume III. Cumulative distribution of forces on structures subjected to the combined action of currents and random waves for potential OTEC sites: (A) Keahole Point, Hawaii, 100 year hurricane; (B) Punta Tuna, Puerto Rico, 100 year hurricane; (C) New Orleans, Louisiana, 100 year hurricane; (D) West Coast of Florida, 100 year hurricane. [CUFOR code

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

Venezian, G.; Bretschneider, C.L.

1980-08-01

This volume details a new methodology to analyze statistically the forces experienced by a structure at sea. Conventionally a wave climate is defined using a spectral function. The wave climate is described using a joint distribution of wave heights and periods (wave lengths), characterizing actual sea conditions through some measured or estimated parameters like the significant wave height, maximum spectral density, etc. Random wave heights and periods satisfying the joint distribution are then generated. Wave kinetics are obtained using linear or non-linear theory. In the case of currents a linear wave-current interaction theory of Venezian (1979) is used. The peakmore » force experienced by the structure for each individual wave is identified. Finally, the probability of exceedance of any given peak force on the structure may be obtained. A three-parameter Longuet-Higgins type joint distribution of wave heights and periods is discussed in detail. This joint distribution was used to model sea conditions at four potential OTEC locations. A uniform cylindrical pipe of 3 m diameter, extending to a depth of 550 m was used as a sample structure. Wave-current interactions were included and forces computed using Morison's equation. The drag and virtual mass coefficients were interpolated from published data. A Fortran program CUFOR was written to execute the above procedure. Tabulated and graphic results of peak forces experienced by the structure, for each location, are presented. A listing of CUFOR is included. Considerable flexibility of structural definition has been incorporated. The program can easily be modified in the case of an alternative joint distribution or for inclusion of effects like non-linearity of waves, transverse forces and diffraction.« less

Estimating the hemodynamic influence of variable main body-to-iliac limb length ratios in aortic endografts.

PubMed

Georgakarakos, Efstratios; Xenakis, Antonios; Georgiadis, George S

2018-02-01

We conducted a computational study to assess the hemodynamic impact of variant main body-to-iliac limb length (L1/L2) ratios on certain hemodynamic parameters acting on the endograft (EG) either on the normal bifurcated (Bif) or the cross-limb (Cx) fashion. A customary bifurcated 3D model was computationally created and meshed using the commercially available ANSYS ICEM (Ansys Inc., Canonsburg, PA, USA) software. The total length of the EG, was kept constant, while the L1/L2 ratio ranged from 0.3 to 1.5 in the Bif and Cx reconstructed EG models. The compliance of the graft was modeled using a Fluid Structure Interaction method. Important hemodynamic parameters such as pressure drop along EG, wall shear stress (WSS) and helicity were calculated. The greatest pressure decrease across EG was calculated in the peak systolic phase. With increasing L1/L2 it was found that the Pressure Drop was increasing for the Cx configuration, while decreasing for the Bif. The greatest helicity (4.1 m/s2) was seen in peak systole of Cx with ratio of 1.5 whereas its greatest value (2 m/s2) was met in peak systole in the Bif with the shortest L1/L2 ratio (0.3). Similarly, the maximum WSS value was highest (2.74Pa) in the peak systole for the 1.5 L1/L2 of the Cx configuration, while the maximum WSS value equaled 2 Pa for all length ratios of the Bif modification (with the WSS found for L1/L2=0.3 being marginally higher). There was greater discrepancy in the WSS values for all L1/L2 ratios of the Cx bifurcation compared to Bif. Different L1/L2 rations are shown to have an impact on the pressure distribution along the entire EG while the length ratio predisposing to highest helicity or WSS values is also determined by the iliac limbs pattern of the EG. Since current custom-made EG solutions can reproduce variability in main-body/iliac limbs length ratios, further computational as well as clinical research is warranted to delineate and predict the hemodynamic and clinical effect of variable length ratios.

Spatial distribution of impacts to channel bed mobility due to flow regulation, Kootenai River, USA

Treesearch

Michael Burke; Klaus Jorde; John M. Buffington; Jeffrey H. Braatne; Rohan Benjakar

2006-01-01

The regulated hydrograph of the Kootenai River between Libby Dam and Kootenay Lake has altered the natural flow regime, resulting in a significant decrease in maximum flows (60% net reduction in median 1-day annual maximum, and 77%-84% net reductions in median monthly flows for the historic peak flow months of May and June, respectively). Other key hydrologic...

Major and Daytime Meteor Showers using Global Radio Meteor Observations covering the period 2001-2016

NASA Astrophysics Data System (ADS)

Ogawa, Hiroshi; Steyaert, Christian

2017-10-01

With radio, it is possible to observe meteor activity even in bad weather and during daytime. The research in this paper succeeded in detecting the important stream features, such as peak time, peak level and FWHM (Full Width Half Maximum) in not only major streams but also daytime meteor showers, using worldwide radio forward scattering data covering the period 2001-2016.

12  mJ Yb:YAG/Cr:YAG microchip laser.

PubMed

Guo, Xiaoyang; Tokita, Shigeki; Kawanaka, Junji

2018-02-01

We have developed a quasi-continuous wave diode end-pumped cryogenically cooled Yb:YAG/Cr:YAG passively Q-switched microchip laser. A maximum energy of 12.1 mJ with 3.7 MW of peak power was obtained. To the best of our knowledge, this is the highest energy and peak power obtained by an Yb:YAG/Cr:YAG microchip laser so far.

[Energy accumulation and allocation of main plant populations in Aneurolepidium chinense grassland in Songnen Plain].

PubMed

Qu, Guohui; Wen, Mingzhang; Guo, Jixun

2003-05-01

The calorific value of plants is dependent on their biological characteristics and energy-containing materials. The allocation of calorific value in different organs of Aneurolepidium chinese, Calamagrostic epigejos, Puccinellia tenuiflora and Chloris virgata was inflorescence > leaf > stem > dead standing. The seasonal dynamics of standing crop energy of aboveground part of four plant populations showed single-peak curve, and the energy production was Aneurolepidium chinense > Calamagrostic epigejos > Chloris virgata > Puccinellia tenuiflora. Energy increasing rate showed double-peak curve, with the first peak at heading stage and the second peak at maturing stage of seeds. Energy increasing rate was negative at the final stage of growth. The horizontal distribution of energy of aboveground part was that the allocation ratio of different organs at different growth stages was different. There existed a similar trend for vertical distribution of energy among four plant populations, i.e., was the vertical distribution of energy of aboveground part showed a tower shape, with the maximum value in 10-30 cm height. The vertical distribution of energy of underground part showed an inverted tower shape from soil surface to deeper layer, with the maximum value in 0-10 cm depth. The standing crop energy of underground part was about 3-4 times than that of aboveground part.

Multiple negative differential resistance devices with ultra-high peak-to-valley current ratio for practical multi-valued logic and memory applications

NASA Astrophysics Data System (ADS)

Shin, Sunhae; Rok Kim, Kyung

2015-06-01

In this paper, we propose a novel multiple negative differential resistance (NDR) device with ultra-high peak-to-valley current ratio (PVCR) over 106 by combining tunnel diode with a conventional MOSFET, which suppresses the valley current with transistor off-leakage level. Band-to-band tunneling (BTBT) in tunnel junction provides the first peak, and the second peak and valley are generated from the suppression of diffusion current in tunnel diode by the off-state MOSFET. The multiple NDR curves can be controlled by doping concentration of tunnel junction and the threshold voltage of MOSFET. By using complementary multiple NDR devices, five-state memory is demonstrated only with six transistors.

Lightning Characteristics and Lightning Strike Peak Current Probabilities as Related to Aerospace Vehicle Operations

NASA Technical Reports Server (NTRS)

Johnson, Dale L.; Vaughan, William W.

1998-01-01

A summary is presented of basic lightning characteristics/criteria for current and future NASA aerospace vehicles. The paper estimates the probability of occurrence of a 200 kA peak lightning return current, should lightning strike an aerospace vehicle in various operational phases, i.e., roll-out, on-pad, launch, reenter/land, and return-to-launch site. A literature search was conducted for previous work concerning occurrence and measurement of peak lighting currents, modeling, and estimating probabilities of launch vehicles/objects being struck by lightning. This paper presents these results.

Vertical Structure of Ice Cloud Layers From CloudSat and CALIPSO Measurements and Comparison to NICAM Simulations

NASA Technical Reports Server (NTRS)

Ham, Seung-Hee; Sohn, Byung-Ju; Kato, Seiji; Satoh, Masaki

2013-01-01

The shape of the vertical profile of ice cloud layers is examined using 4 months of CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) global measurements taken on January, April, July, and October 2007. Ice clouds are selected using temperature profiles when the cloud base is located above the 253K temperature level. The obtained ice water content (IWC), effective radius, or extinction coefficient profiles are normalized by their layer mean values and are expressed in the normalized vertical coordinate, which is defined as 0 and 1 at the cloud base and top heights, respectively. Both CloudSat and CALIPSO observations show that the maximum in the IWC and extinction profiles shifts toward the cloud bottom, as the cloud depth increases. In addition, clouds with a base reaching the surface in a high-latitude region show that the maximum peak of the IWC and extinction profiles occurs near the surface, which is presumably due to snow precipitation. CloudSat measurements show that the seasonal difference in normalized cloud vertical profiles is not significant, whereas the normalized cloud vertical profile significantly varies depending on the cloud type and the presence of precipitation. It is further examined if the 7 day Nonhydrostatic Icosahedral Atmospheric Model (NICAM) simulation results from 25 December 2006 to 1 January 2007 generate similar cloud profile shapes. NICAM IWC profiles also show maximum peaks near the cloud bottom for thick cloud layers and maximum peaks at the cloud bottom for low-level clouds near the surface. It is inferred that oversized snow particles in the NICAM cloud scheme produce a more vertically inhomogeneous IWC profile than observations due to quick sedimentation.

Does team lifting increase the variability in peak lumbar compression in ironworkers?

PubMed

Faber, Gert; Visser, Steven; van der Molen, Henk F; Kuijer, P Paul F M; Hoozemans, Marco J M; Van Dieën, Jaap H; Frings-Dresen, Monique H W

2012-01-01

Ironworkers frequently perform heavy lifting tasks in teams of two or four workers. Team lifting could potentially lead to a higher variation in peak lumbar compression forces than lifts performed by one worker, resulting in higher maximal peak lumbar compression forces. This study compared single-worker lifts (25-kg, iron bar) to two-worker lifts (50-kg, two iron bars) and to four-worker lifts (100-kg, iron lattice). Inverse dynamics was used to calculate peak lumbar compression forces. To assess the variability in peak lumbar loading, all three lifting tasks were performed six times. Results showed that the variability in peak lumbar loading was somewhat higher in the team lifts compared to the single-worker lifts. However, despite this increased variability, team lifts did not result in larger maximum peak lumbar compression forces. Therefore, it was concluded that, from a biomechanical point of view, team lifting does not result in an additional risk for low back complaints in ironworkers.

The Southern Glacial Maximum 65,000 years ago and its Unfinished Termination

NASA Astrophysics Data System (ADS)

Schaefer, Joerg M.; Putnam, Aaron E.; Denton, George H.; Kaplan, Michael R.; Birkel, Sean; Doughty, Alice M.; Kelley, Sam; Barrell, David J. A.; Finkel, Robert C.; Winckler, Gisela; Anderson, Robert F.; Ninneman, Ulysses S.; Barker, Stephen; Schwartz, Roseanne; Andersen, Bjorn G.; Schluechter, Christian

2015-04-01

Glacial maxima and their terminations provide key insights into inter-hemispheric climate dynamics and the coupling of atmosphere, surface and deep ocean, hydrology, and cryosphere, which is fundamental for evaluating the robustness of earth's climate in view of ongoing climate change. The Last Glacial Maximum (LGM, ∼26-19 ka ago) is widely seen as the global cold peak during the last glacial cycle, and its transition to the Holocene interglacial, dubbed 'Termination 1 (T1)', as the most dramatic climate reorganization during this interval. Climate records show that over the last 800 ka, ice ages peaked and terminated on average every 100 ka ('100 ka world'). However, the mechanisms pacing glacial-interglacial transitions remain controversial and in particular the hemispheric manifestations and underlying orbital to regional driving forces of glacial maxima and subsequent terminations remain poorly understood. Here we show evidence for a full glacial maximum in the Southern Hemisphere 65.1 ± 2.7 ka ago and its 'Unfinished Termination'. Our 10Be chronology combined with a model simulation demonstrates that New Zealand's glaciers reached their maximum position of the last glacial cycle during Marine Isotope Stage-4 (MIS-4). Southern ocean and greenhouse gas records indicate coeval peak glacial conditions, making the case for the Southern Glacial Maximum about halfway through the last glacial cycle and only 15 ka after the last warm period (MIS-5a). We present the hypothesis that subsequently, driven by boreal summer insolation forcing, a termination began but remained unfinished, possibly because the northern ice sheets were only moderately large and could not supply enough meltwater to the North Atlantic through Heinrich Stadial 6 to drive a full termination. Yet the Unfinished Termination left behind substantial ice on the northern continents (about 50% of the full LGM ice volume) and after another 45 ka of cooling and ice sheet growth the earth was at inter-hemispheric Last Glacial Maximum configuration, when similar orbital forcing hit maximum-size northern ice sheets and ushered in T1 and thus the ongoing interglacial. This argument highlights the critical role of full glacial conditions in both hemispheres for terminations and implies that the Southern Hemisphere climate could transition from interglacial to full glacial conditions in about 15,000 years, while the Northern Hemisphere and its continental ice-sheets required half a glacial cycle.

An experimental study on effect of coke ratio on SO2 and NOx emissions in sintering process

NASA Astrophysics Data System (ADS)

Wang, Hui; Zhang, Pu; Yang, Jingling

2018-02-01

By using the sinter cup experiment, the effects of different coke ratios of 0%, 25%, 50%, 75%, and 100% on the formation and total emissions of SO2 and NOx in the sintering process were studied with the Testo350 flue gas analyzer. The experimental results show that the emissions of SO2 and NOx are closely related to sintering process. With the increase of the coke proportion, the sintering temperature changes and the maximum peak time appears earlier. SO2 concentration has a bimodal distribution and NOx concentration has a triple peak. Besides, the both maximum peaks appear at the end of sintering. In addition, due to the increasing of the S and N contents in the fuel with the coke ratios from 0% to 100%, the amounts of SO2 and NOx emissions are raised respectively at 10.82 mg, 11.42 mg, 13.84 mg, 13.69 mg, 20.36 mg and 3.11 mg, 3.39 mg, 4.44 mg, 4.31 mg, 6.16 mg.

Effects of UV light intensity on electrochemical wet etching of SiC for the fabrication of suspended graphene

NASA Astrophysics Data System (ADS)

O, Ryong-Sok; Takamura, Makoto; Furukawa, Kazuaki; Nagase, Masao; Hibino, Hiroki

2015-03-01

We report on the effects of UV light intensity on the photo assisted electrochemical wet etching of SiC(0001) underneath an epitaxially grown graphene for the fabrication of suspended structures. The maximum etching rate of SiC(0001) was 2.5 µm/h under UV light irradiation in 1 wt % KOH at a constant current of 0.5 mA/cm2. The successful formation of suspended structures depended on the etching rate of SiC. In the Raman spectra of the suspended structures, we did not observe a significant increase in the intensity of the D peak, which originates from defects in graphene sheets. This is most likely explained by the high quality of the single-crystalline graphene epitaxially grown on SiC.

Highly efficient phosphorescence from organic light-emitting devices with an exciton-block layer

NASA Astrophysics Data System (ADS)

Ikai, Masamichi; Tokito, Shizuo; Sakamoto, Youichi; Suzuki, Toshiyasu; Taga, Yasunori

2001-07-01

One of the keys to highly efficient phosphorescent emission in organic light-emitting devices is to confine triplet excitons generated within the emitting layer. We employ "starburst" perfluorinated phenylenes (C60F42) as a both hole- and exciton-block layer, and a hole-transport material 4,4',4″-tri(N-carbazolyl) triphenylamine as a host for the phosphorescent dopant dye in the emitting layer. A maximum external quantum efficiency reaches to 19.2%, and keeps over 15% even at high current densities of 10-20 mA/cm2, providing several times the brightness of fluorescent tubes for lighting. The onset voltage of the electroluminescence is as low as 2.4 V and the peak power efficiency is 70-72 lm/W, promising for low-power display devices.

Active stabilization of a diode laser injection lock.

PubMed

Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

2016-06-01

We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

Enhanced amperometric detection of metronidazole in drug formulations and urine samples based on chitosan protected tetrasulfonated copper phthalocyanine thin-film modified glassy carbon electrode.

PubMed

Meenakshi, S; Pandian, K; Jayakumari, L S; Inbasekaran, S

2016-02-01

An enhanced electrocatalytic reduction of metronidazole antibiotic drug molecule using chitosan protected tetrasulfonated copper phthalocyanine (Chit/CuTsPc) thin-film modified glassy carbon electrode (GCE) has been developed. An irreversible reduction occurs at -0.47V (vs. Ag/AgCl) using Chit/CuTsPc modified GCE. A maximum peak current value is obtained at pH1 and the electrochemical reduction reaction is a diffusion controlled one. The detection limit is found to be 0.41nM from differential pulse voltammetry (DPV) method. This present investigation method is adopted for electrochemical detection of metronidazole in drug formulation and urine samples by using DPV method. Copyright © 2015 Elsevier B.V. All rights reserved.

10th order laterally coupled GaN-based DFB laser diodes with V-shaped surface gratings

NASA Astrophysics Data System (ADS)

Kang, J. H.; Wenzel, H.; Hoffmann, V.; Freier, E.; Sulmoni, L.; Unger, R.-S.; Einfeldt, S.; Wernicke, T.; Kneissl, M.

2018-02-01

Single longitudinal mode operation of laterally coupled distributed feedback (DFB) laser diodes (LDs) based on GaN containing 10th-order surface Bragg gratings with V-shaped grooves is demonstrated using i-line stepper lithography and inductively coupled plasma etching. A threshold current of 82 mA, a slope efficiency of 1.7 W/A, a single peak emission at 404.5 nm with a full width at half maximum of 0.04 nm and a side mode suppression ratio of > 23 dB at an output power of about 46 mW were achieved under pulsed operation. The shift of the lasing wavelength of DFB LDs with temperature was around three times smaller than that of conventional ridge waveguide LDs.

A realistic treatment of geomagnetic Cherenkov radiation from cosmic ray air showers

NASA Astrophysics Data System (ADS)

Werner, Klaus; de Vries, Krijn D.; Scholten, Olaf

2012-09-01

We present a macroscopic calculation of coherent electro-magnetic radiation from air showers initiated by ultra-high energy cosmic rays, based on currents obtained from three-dimensional Monte Carlo simulations of air showers in a realistic geo-magnetic field. We discuss the importance of a correct treatment of the index of refraction in air, given by the law of Gladstone and Dale, which affects the pulses enormously for certain configurations, compared to a simplified treatment using a constant index. We predict in particular a geomagnetic Cherenkov radiation, which provides strong signals at high frequencies (GHz), for certain geometries together with "normal radiation" from the shower maximum, leading to a double peak structure in the frequency spectrum. We also provide some information about the numerical procedures referred to as EVA 1.0.

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

Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser’s transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399more » nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.« less

Growth and characterization of high current density, high-speed InAs/AlSb resonant tunneling diodes

NASA Technical Reports Server (NTRS)

Soderstrom, J. R.; Brown, E. R.; Parker, C. D.; Mahoney, L. J.; Yao, J. Y.

1991-01-01

InAs/AlSb double-barrier resonant tunneling diodes with peak current densities up to 370,000 A/sq cm and high peak-to-valley current ratios of 3.2 at room temperature have been fabricated. The peak current density is well-explained by a stationary-state transport model with the two-band envelope function approximation. The valley current density predicted by this model is less than the experimental value by a factor that is typical of the discrepancy found in other double-barrier structures. It is concluded that threading dislocations are largely inactive in the resonant tunneling process.

Associations Between Rate of Force Development Metrics and Throwing Velocity in Elite Team Handball Players: a Short Research Report

PubMed Central

Marques, Mário C.; Saavedra, Francisco J.; Abrantes, Catarina; Aidar, Felipe J.

2011-01-01

Performance assessment has become an invaluable component of monitoring participant’s development in distinct sports, yet limited and contradictory data are available in trained subjects. The purpose of this study was to examine the relationship between ball throwing velocity during a 3-step running throw in elite team handball players and selected measures of rate of force development like force, power, velocity, and bar displacement during a concentric only bench press exercise in elite male handball players. Fitteen elite senior male team handball players volunteered to participate. Each volunteer had power and bar velocity measured during a concentric only bench press test with 25, 35, and 45 kg as well as having one-repetition maximum strength determined. Ball throwing velocity was evaluated with a standard 3-step running throw using a radar gun. The results of this study indicated significant associations between ball velocity and time at maximum rate of force development (0, 66; p<0.05) and rate of force development at peak force (0,56; p<0.05) only with 25kg load. The current research indicated that ball velocity was only median associated with maximum rate of force development with light loads. A training regimen designed to improve ball-throwing velocity in elite male team handball players should emphasize bench press movement using light loads. PMID:23487363

Physical and economic potential of geological CO2 storage in saline aquifers.

PubMed

Eccles, Jordan K; Pratson, Lincoln; Newell, Richard G; Jackson, Robert B

2009-03-15

Carbon sequestration in sandstone saline reservoirs holds great potential for mitigating climate change, but its storage potential and cost per ton of avoided CO2 emissions are uncertain. We develop a general model to determine the maximum theoretical constraints on both storage potential and injection rate and use it to characterize the economic viability of geosequestration in sandstone saline aquifers. When applied to a representative set of aquifer characteristics, the model yields results that compare favorably with pilot projects currently underway. Over a range of reservoir properties, maximum effective storage peaks at an optimal depth of 1600 m, at which point 0.18-0.31 metric tons can be stored per cubic meter of bulk volume of reservoir. Maximum modeled injection rates predict minima for storage costs in a typical basin in the range of $2-7/ ton CO2 (2005 U.S.$) depending on depth and basin characteristics in our base-case scenario. Because the properties of natural reservoirs in the United States vary substantially, storage costs could in some cases be lower or higher by orders of magnitude. We conclude that available geosequestration capacity exhibits a wide range of technological and economic attractiveness. Like traditional projects in the extractive industries, geosequestration capacity should be exploited starting with the low-cost storage options first then moving gradually up the supply curve.

Associations between rate of force development metrics and throwing velocity in elite team handball players: a short research report.

PubMed

Marques, Mário C; Saavedra, Francisco J; Abrantes, Catarina; Aidar, Felipe J

2011-09-01

Performance assessment has become an invaluable component of monitoring participant's development in distinct sports, yet limited and contradictory data are available in trained subjects. The purpose of this study was to examine the relationship between ball throwing velocity during a 3-step running throw in elite team handball players and selected measures of rate of force development like force, power, velocity, and bar displacement during a concentric only bench press exercise in elite male handball players. Fitteen elite senior male team handball players volunteered to participate. Each volunteer had power and bar velocity measured during a concentric only bench press test with 25, 35, and 45 kg as well as having one-repetition maximum strength determined. Ball throwing velocity was evaluated with a standard 3-step running throw using a radar gun. The results of this study indicated significant associations between ball velocity and time at maximum rate of force development (0, 66; p<0.05) and rate of force development at peak force (0,56; p<0.05) only with 25kg load. The current research indicated that ball velocity was only median associated with maximum rate of force development with light loads. A training regimen designed to improve ball-throwing velocity in elite male team handball players should emphasize bench press movement using light loads.

Random walk on a leash: a simple single-molecule diffusion model for surface-tethered redox molecules with flexible linkers.

PubMed

Huang, Kuan-Chun; White, Ryan J

2013-08-28

We develop a random walk model to simulate the Brownian motion and the electrochemical response of a single molecule confined to an electrode surface via a flexible molecular tether. We use our simple model, which requires no prior knowledge of the physics of the molecular tether, to predict and better understand the voltammetric response of surface-confined redox molecules when motion of the redox molecule becomes important. The single molecule is confined to a hemispherical volume with a maximum radius determined by the flexible molecular tether (5-20 nm) and is allowed to undergo true three-dimensional diffusion. Distance- and potential-dependent electron transfer probabilities are evaluated throughout the simulations to generate cyclic voltammograms of the model system. We find that at sufficiently slow cyclic voltammetric scan rates the electrochemical reaction behaves like an adsorbed redox molecule with no mass transfer limitation; thus, the peak current is proportional to the scan rate. Conversely, at faster scan rates the diffusional motion of the molecule limits the simulated peak current, which exhibits a linear dependence on the square root of the scan rate. The switch between these two limiting regimes occurs when the diffusion layer thickness, (2Dt)(1/2), is ~10 times the tether length. Finally, we find that our model predicts the voltammetric behavior of a redox-active methylene blue tethered to an electrode surface via short flexible single-stranded, polythymine DNAs, allowing the estimation of diffusion coefficients for the end-tethered molecule.

The interactive effects of estrogen and progesterone on changes in emotional eating across the menstrual cycle.

PubMed

Klump, Kelly L; Keel, Pamela K; Racine, Sarah E; Burt, S Alexandra; Burt, Alexandra S; Neale, Michael; Sisk, Cheryl L; Boker, Steven; Hu, Jean Yueqin

2013-02-01

Studies suggest that within-person changes in estrogen and progesterone predict changes in binge eating across the menstrual cycle. However, samples have been extremely small (maximum N = 9), and analyses have not examined the interactive effects of hormones that are critical for changes in food intake in animals. The aims of the current study were to examine ovarian hormone interactions in the prediction of within-subject changes in emotional eating in the largest sample of women to date (N = 196). Participants provided daily ratings of emotional eating and saliva samples for hormone measurement for 45 consecutive days. Results confirmed that changes in ovarian hormones predict changes in emotional eating across the menstrual cycle, with a significant estradiol × progesterone interaction. Emotional eating scores were highest during the midluteal phase, when progesterone peaks and estradiol demonstrates a secondary peak. Findings extend previous work by highlighting significant interactions between estrogen and progesterone that explain midluteal increases in emotional eating. Future work should explore mechanisms (e.g., gene-hormone interactions) that contribute to both within- and between-subjects differences in emotional eating. 2013 APA, all rights reserved

Prediction Methods in Solar Sunspots Cycles

PubMed Central

Ng, Kim Kwee

2016-01-01

An understanding of the Ohl’s Precursor Method, which is used to predict the upcoming sunspots activity, is presented by employing a simplified movable divided-blocks diagram. Using a new approach, the total number of sunspots in a solar cycle and the maximum averaged monthly sunspots number Rz(max) are both shown to be statistically related to the geomagnetic activity index in the prior solar cycle. The correlation factors are significant and they are respectively found to be 0.91 ± 0.13 and 0.85 ± 0.17. The projected result is consistent with the current observation of solar cycle 24 which appears to have attained at least Rz(max) at 78.7 ± 11.7 in March 2014. Moreover, in a statistical study of the time-delayed solar events, the average time between the peak in the monthly geomagnetic index and the peak in the monthly sunspots numbers in the succeeding ascending phase of the sunspot activity is found to be 57.6 ± 3.1 months. The statistically determined time-delayed interval confirms earlier observational results by others that the Sun’s electromagnetic dipole is moving toward the Sun’s Equator during a solar cycle. PMID:26868269

Two-dimensional CdS nanosheet-based TFT and LED nanodevices.

PubMed

Ye, Yu; Yu, Bin; Gao, Zhiwei; Meng, Hu; Zhang, Hui; Dai, Lun; Qin, Guogang

2012-05-17

Semiconductor nanosheets have several unique applications in electronic and optoelectronic nanodevices. We have successfully synthesized single-crystalline n-type CdS nanosheets via a chemical vapor deposition (CVD) method in a Cd-enriched ambient. The as-synthesized nanosheets are typically 40-100 nm thick, 10-300 µm wide, and up to several millimeters long. Using the nanosheets, we fabricated for the first time (to our knowledge), nano thin-film transistors (nano-TFTs) based on individual CdS nanosheets. A typical unit of such nanosheet TFTs has a high on-off ratio (∼1.7 ×10(9)) and peak transconductance (∼14.1µS), which to our knowledge are the best values reported so far for semiconductor nano-TFTs. In addition, we fabricated n-CdS nanosheet/p(+)-Si heterojunction light emitting diodes (LEDs) with a top electrode structure. This structure, where the n-type electrode is directly above the junction, has the advantage of a large active region and injection current favorable for high-efficiency electroluminescence (EL) and lasing. Room-temperature spectra of the LEDs consist of only an intense CdS band-edge emission peak (∼507.7 nm) with a full width at half-maximum of about 14 nm.

An enhanced low-frequency vibration ZnO nanorod-based tuning fork piezoelectric nanogenerator.

PubMed

Deng, Weili; Jin, Long; Chen, Yueqi; Chu, Wenjun; Zhang, Binbin; Sun, Huan; Xiong, Da; Lv, Zekai; Zhu, Minhao; Yang, Weiqing

2018-01-03

In this paper, a piezoelectric nanogenerator (PENG) based on a tuning fork-shaped cantilever was designed and fabricated, aiming at harvesting low frequency vibration energy in the environment. In the PENG, a tuning fork-shaped elastic beam combined with ZnO nanorods (NRs), instead of conventional rectangular cantilever beams, was adopted to extract vibration energy. Benefiting from the high flexibility and the controllable shape of the substrate, this PENG was extremely sensitive to vibration and can harvest weak vibration energy at a low frequency. Moreover, a series of simulation models were established to compare the performance of the PENG with that of different shapes. On this basis, the experimental results further verify that this designed energy harvester could operate at a low frequency which was about 13 Hz. The peak output voltage and current could respectively reach about 160 mV and 11 nA, and a maximum instantaneous peak power of 0.92 μW cm -3 across a matched load of 9 MΩ was obtained. Evidently, this newly designed PENG could harvest vibration energy at a lower frequency, which will contribute to broaden the application range of the PENG in energy harvesting and self-powered systems.

An observational study of the nightside ionospheres of Mars and Venus with radio occultation methods

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

Zhang, M.H.G.; Luhmann, J.G.; Kliore, A.J.

1990-10-01

An analysis of Mars and Venus nightside electron density profiles obtained with radio occultation methods shows how the nightside ionospheres of both planets vary with solar zenith angle. From previous studies it is known that the dayside peak electron densities at Mars and Venus show a basic similarity in that they both exhibit Chapman layer-like behavior. In contrast, the peak altitudes at mars behave like an ideal Chapman layer on the dayside, whereas the altitude of the peak at Venus is fairly constant up to the terminator. The effect of major dust storms can also be seen in the peakmore » altitudes at Mars. All Venus nightside electron density profiles show a distinct main peak for both solar minimum and maximum, whereas many profiles from the nightside of Mars do not show any peak at all. This suggests that the electron density in the Mars nightside ionosphere is frequently too low to be detected by radio occultation. On the Pioneer Venus orbiter, disappearing ionospheres were observed near solar maximum in the in-situ data when the solar wind dynamic pressure was exceptionally high. This condition occurs because the high solar wind dynamic pressure decreases the altitude of the ionopause near the terminator below {approximately}250 km, thus reducing the normal nightward transport of dayside ionospheric plasma. On the basis of the Venus observations, one might predict that if a positive correlation of nightside peak density with dynamic pressure was found, it could mean that transport from the dayside is the only significant source for the nightside ionosphere of Mars. The lack of a correlation would imply that the precipitation source at Mars is quite variable.« less

Comparison of VO[subscript 2] Maximum Obtained from 20 m Shuttle Run and Cycle Ergometer in Children with and without Developmental Coordination Disorder

ERIC Educational Resources Information Center

Cairney, John; Hay, John; Veldhuizen, Scott; Faught, Brent

2010-01-01

Oxygen consumption at peak physical exertion (VO[subscript 2] maximum) is the most widely used indicator of cardiorespiratory fitness. The purpose of this study was to compare two protocols for its estimation, cycle ergometer testing and the 20 m shuttle run, among children with and without probable developmental coordination disorder (pDCD). The…

A model-based method for estimating Ca2+ release fluxes from linescan images in Xenopus oocytes.

PubMed

Baran, Irina; Popescu, Anca

2009-09-01

We propose a model-based method of interpreting linescan images observed in Xenopus oocytes with the use of Oregon Green-1 as a fluorescent dye. We use a detailed modeling formalism based on numerical simulations that incorporate physical barriers for local diffusion, and, by assuming a Gaussian distribution of release durations, we derive the distributions of release Ca(2+) amounts and currents, fluorescence amplitudes, and puff widths. We analyze a wide set of available data collected from 857 and 281 events observed in the animal and the vegetal hemispheres of the oocyte, respectively. A relatively small fraction of events appear to involve coupling of two or three adjacent clusters of Ca(2+) releasing channels. In the animal hemisphere, the distribution of release currents with a mean of 1.4 pA presents a maximum at 1.0 pA and a rather long tail extending up to 5 pA. The overall distribution of liberated Ca(2+) amounts exhibits a dominant peak at 120 fC, a smaller peak at 375 fC, and an average of 166 fC. Ca(2+) amounts and release fluxes in the vegetal hemisphere appear to be 3.6 and 1.6 times smaller than in the animal hemisphere, respectively. Predicted diameters of elemental release sites are approximately 1.0 microm in the animal and approximately 0.5 microm in the vegetal hemisphere, but the side-to-side separation between adjacent sites appears to be identical (approximately 0.4 microm). By fitting the model to individual puffs we can estimate the quantity of liberated calcium, the release current, the orientation of the scan line, and the dimension of the corresponding release site.

Experimental investigation of high power pulsed 2.8 μm Er3+-doped ZBLAN fiber lasers

NASA Astrophysics Data System (ADS)

Shen, Yanlong; Wang, Yishan; Huang, Ke; Luan, Kunpeng; Chen, Hongwei; Tao, Mengmeng; Yu, Li; Yi, Aiping; Si, Jinhai

2017-05-01

We report on the recent progress on high power pulsed 2.8 μm Er3+-doped ZBLAN fiber laser through techniques of passively and actively Q-switching in our research group. In passively Q-switched operation, a diode-cladding-pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) was demonstrated. Stable pulse train was produced at a slope efficient of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ. The maximum peak power was calculated to be 21.9 W. In actively Q-switched operation, a diode-pumped actively Q-switched Er3+-doped ZBLAN fiber laser at 2.8 μm with an optical chopper was reported. The maximum laser pulse energy of up to 130 μJ and a pulse width of 127.3 ns at a repetition rate of 10 kHz with an operating wavelength of 2.78 μm was obtained, yielding the maximum peak power of exceeding 1.1 kW.

Lower Extremity Kinematics During a Drop Jump in Individuals With Patellar Tendinopathy

PubMed Central

Rosen, Adam B.; Ko, Jupil; Simpson, Kathy J.; Kim, Seock-Ho; Brown, Cathleen N.

2015-01-01

Background: Patellar tendinopathy (PT) is a common degenerative condition in physically active populations. Knowledge regarding the biomechanics of landing in populations with symptomatic PT is limited, but altered mechanics may play a role in the development or perpetuation of PT. Purpose: To identify whether study participants with PT exhibited different landing kinematics compared with healthy controls. Study Design: Controlled laboratory study. Methods: Sixty recreationally active participants took part in this study; 30 had current signs and symptoms of PT, including self-reported pain within the patellar tendon during loading activities for at least 3 months and ≤80 on the Victorian Institute of Sport Assessment Scale–Patella (VISA-P). Thirty healthy participants with no history of PT or other knee joint pathology were matched by sex, age, height, and weight. Participants completed 5 trials of a 40-cm, 2-legged drop jump followed immediately by a 50% maximum vertical jump. Dependent variables of interest included hip, knee, and ankle joint angles at initial ground contact, peak angles, and maximum angular displacements during the landing phase in 3 planes. Independent-samples t tests (P ≤ .05) were utilized to compare the joint angles and angular displacements between PT and control participants. Results: Individuals with PT displayed significantly decreased peak hip (PT, 59.2° ± 14.6°; control, 67.2° ± 13.9°; P = .03) and knee flexion angles (PT, 74.8° ± 13.2°; control, 82.5° ± 9.0°; P = .01) compared with control subjects. The PT group displayed decreased maximum angular displacement in the sagittal plane at the hip (PT, 49.3° ± 10.8°; control, 55.2° ± 11.4°; P = .04) and knee (PT, 71.6° ± 8.4°; control, 79.7° ± 8.3°; P < .001) compared with the control group. Conclusion: Participants with PT displayed decreased maximum flexion and angular displacement in the sagittal plane, at both the knee and the hip. The altered movement patterns in those with PT may be perpetuating symptoms associated with PT and could be due to the contributions of the rectus femoris during dynamic movement. Clinical Relevance: Based on kinematic alterations in symptomatic participants, rehabilitation efforts may benefit from focusing on both the knee and the hip to treat symptoms associated with PT. PMID:26665034

Global characteristics in the diurnal variations of the thermospheric temperature and composition

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Hedin, A. E.; Reber, C. A.; Carignan, G. R.

1973-01-01

Global characteristics in the diurnal components of OGO-6 neutral mass spectrometer measurements near 450 km are discussed qualitatively as well as quantitatively on the basis of a theoretical model. Observations and conclusion are summarized: (1) During equinox the temperature maximum occurs after 1600 LT at the equator and shifts toward 1500 LT at the poles, while the oxygen concentration at 450 km peaks about one hour earlier. (2) There is general agreement between the magnitudes and phases of the diurnal, semidiurnal and terdiuranal temperature components at 450 km from theory as well as OGO-6 and radar backscatter measurements. (3) The maximum in the diurnal variation of He is observed near 1030 LT consistent with theoretical results which further emphasize the importance of dynamics and diffusion. (4) During solstice conditions the diurnal temperature maximum shifts toward later local times, in substantial agreement with radar temperature measurements. (5) the temperature-oxygen density phase difference at 450 km is observed to decrease with latitude from the winter toward the summer hemisphere, where oxygen may even peak after the temperature at high latitudes.

Improving maximum power point tracking of partially shaded photovoltaic system by using IPSO-BELBIC

NASA Astrophysics Data System (ADS)

Al-Alim El-Garhy, M. Abd; Mubarak, R. I.; El-Bably, M.

2017-08-01

Solar photovoltaic (PV) arrays in remote applications are often related to the rapid changes in the partial shading pattern. Rapid changes of the partial shading pattern make the tracking of maximum power point (MPP) of the global peak through the local ones too difficult. An essential need to make a fast and efficient algorithm to detect the peaks values which always vary as the sun irradiance changes. This paper presents two algorithms based on the improved particle swarm optimization technique one of them with PID controller (IPSO-PID), and the other one with Brain Emotional Learning Based Intelligent Controller (IPSO-BELBIC). These techniques improve the maximum power point (MPP) tracking capabilities for photovoltaic (PV) system under partial shading circumstances. The main aim of these improved algorithms is to accelerate the velocity of IPSO to reach to (MPP) and increase its efficiency. These algorithms also improve the tracking time under complex irradiance conditions. Based on these conditions, the tracking time of these presented techniques improves to 2 msec, with an efficiency of 100%.

2 µm high-power dissipative soliton resonance in a compact σ-shaped Tm-doped double-clad fiber laser

NASA Astrophysics Data System (ADS)

Du, Tuanjie; Li, Weiwei; Ruan, Qiujun; Wang, Kaijie; Chen, Nan; Luo, Zhengqian

2018-05-01

We report direct generation of a high-power, large-energy dissipative soliton resonance (DSR) in a 2 µm Tm-doped double-clad fiber laser. A compact σ-shaped cavity is formed by a fiber Bragg grating and a 10/90 fiber loop mirror (FLM). The 10/90 FLM is not only used as an output mirror, but also acts as a nonlinear optical loop mirror for initiating mode locking. The mode-locked laser can deliver high-power, nanosecond DSR pulses at 2005.9 nm. We further perform a comparison study of the effect of the FLM’s loop length on the mode-locking threshold, peak power, pulse energy, and optical spectrum of the DSR pulses. We achieve a maximum average output power as high as 1.4 W, a maximum pulse energy of 353 nJ, and a maximum peak power of 84 W. This is, to the best of our knowledge, the highest power for 2 µm DSR pulses obtained in a mode-locked fiber laser.

Improving Weak Lensing Mass Map Reconstructions using Gaussian and Sparsity Priors: Application to DES SV

NASA Astrophysics Data System (ADS)

Jeffrey, N.; Abdalla, F. B.; Lahav, O.; Lanusse, F.; Starck, J.-L.; Leonard, A.; Kirk, D.; Chang, C.; Baxter, E.; Kacprzak, T.; Seitz, S.; Vikram, V.; Whiteway, L.; Abbott, T. M. C.; Allam, S.; Avila, S.; Bertin, E.; Brooks, D.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Castander, F. J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Davis, C.; De Vicente, J.; Desai, S.; Doel, P.; Eifler, T. F.; Evrard, A. E.; Flaugher, B.; Fosalba, P.; Frieman, J.; García-Bellido, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Hartley, W. G.; Honscheid, K.; Hoyle, B.; James, D. J.; Jarvis, M.; Kuehn, K.; Lima, M.; Lin, H.; March, M.; Melchior, P.; Menanteau, F.; Miquel, R.; Plazas, A. A.; Reil, K.; Roodman, A.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Walker, A. R.

2018-05-01

Mapping the underlying density field, including non-visible dark matter, using weak gravitational lensing measurements is now a standard tool in cosmology. Due to its importance to the science results of current and upcoming surveys, the quality of the convergence reconstruction methods should be well understood. We compare three methods: Kaiser-Squires (KS), Wiener filter, and GLIMPSE. KS is a direct inversion, not accounting for survey masks or noise. The Wiener filter is well-motivated for Gaussian density fields in a Bayesian framework. GLIMPSE uses sparsity, aiming to reconstruct non-linearities in the density field. We compare these methods with several tests using public Dark Energy Survey (DES) Science Verification (SV) data and realistic DES simulations. The Wiener filter and GLIMPSE offer substantial improvements over smoothed KS with a range of metrics. Both the Wiener filter and GLIMPSE convergence reconstructions show a 12% improvement in Pearson correlation with the underlying truth from simulations. To compare the mapping methods' abilities to find mass peaks, we measure the difference between peak counts from simulated ΛCDM shear catalogues and catalogues with no mass fluctuations (a standard data vector when inferring cosmology from peak statistics); the maximum signal-to-noise of these peak statistics is increased by a factor of 3.5 for the Wiener filter and 9 for GLIMPSE. With simulations we measure the reconstruction of the harmonic phases; the phase residuals' concentration is improved 17% by GLIMPSE and 18% by the Wiener filter. The correlation between reconstructions from data and foreground redMaPPer clusters is increased 18% by the Wiener filter and 32% by GLIMPSE.

Lightning Strike Peak Current Probabilities as Related to Space Shuttle Operations

NASA Technical Reports Server (NTRS)

Johnson, Dale L.; Vaughan, William W.

2000-01-01

A summary is presented of basic lightning characteristics/criteria applicable to current and future aerospace vehicles. The paper provides estimates on the probability of occurrence of a 200 kA peak lightning return current, should lightning strike an aerospace vehicle in various operational phases, i.e., roll-out, on-pad, launch, reenter/land, and return-to-launch site. A literature search was conducted for previous work concerning occurrence and measurement of peak lighting currents, modeling, and estimating the probabilities of launch vehicles/objects being struck by lightning. This paper presents a summary of these results.

Measurements of Tibiofemoral Kinematics During Soft and Stiff Drop Landings Using Biplane Fluoroscopy

PubMed Central

Myers, Casey A.; Torry, Michael R.; Peterson, Daniel S.; Shelburne, Kevin B.; Giphart, J. Erik; Krong, Jacob P.; Woo, Savio L-Y.; Steadman, J. Richard

2014-01-01

Background Previous laboratory studies of landing have defined landing techniques in terms of soft or stiff landings according to the degree of maximal knee flexion angle attained during the landing phase and the relative magnitude of the ground-reaction force. Current anterior cruciate ligament injury prevention programs are instructing athletes to land softly to avoid excessive strain on the anterior cruciate ligament. Purpose This study was undertaken to measure, describe, and compare tibiofemoral rotations and translations of soft and stiff landings in healthy individuals using biplane fluoroscopy. Study Design Controlled laboratory study. Methods The in vivo, lower extremity, 3-dimensional knee kinematics of 16 healthy adults (6 male and 10 female) instructed to land softly and stiffly in different trials were collected in biplane fluoroscopy as they performed the landing from a height of 40 cm. Results Average and maximum relative anterior tibial translation (average, 2.8 ± 1.2 mm vs 3.0 ± 1.4 mm; maximum, 4.7 ± 1.6 mm vs 4.4 ± 0.8 mm), internal/external rotation (average, 3.7° ± 5.1° vs 2.7° ± 4.3°; maximum, 5.6° ± 5.5° vs 4.9° ± 4.7°), and varus/valgus (average, 0.2° ± 1.2° vs 0.2° ± 1.0°; maximum, 1.7° ± 1.2° vs 1.6° ± 0.9°) were all similar between soft and stiff landings, respectively. The peak vertical ground-reaction force was significantly larger for stiff landings than for soft landings (2.60 ± 1.32 body weight vs 1.63 ± 0.73; P < .001). The knee flexion angle total range of motion from the minimum angle at contact to the maximum angle at peak knee flexion was significantly greater for soft landings than for stiff (55.4° ± 8.8° vs 36.8° ± 11.1°; P < .01). Conclusion Stiff landings, as defined by significantly lower knee flexion angles and significantly greater peak ground-reaction forces, do not result in larger amounts of anterior tibial translation or knee rotation in either varus/valgus or internal/external rotation in healthy individuals. Clinical Relevance In healthy knees, the musculature and soft tissues of the knee are able to maintain translations and rotations within a small, safe range during controlled landing tasks of differing demand. The knee kinematics of this healthy population will serve as a comparison for injured knees in future studies. It should be stressed that because the authors did not compare how the loads were distributed over the soft tissues of the knee between the 2 landing styles, the larger ground-reaction forces and more extended knee position observed during stiff landings should still be considered dangerous to the anterior cruciate ligament and other structures of the lower extremities, particularly in competitive settings where movements are often unanticipated. PMID:21602566

Progress toward accurate high spatial resolution actinide analysis by EPMA

NASA Astrophysics Data System (ADS)

Jercinovic, M. J.; Allaz, J. M.; Williams, M. L.

2010-12-01

High precision, high spatial resolution EPMA of actinides is a significant issue for geochronology, resource geochemistry, and studies involving the nuclear fuel cycle. Particular interest focuses on understanding of the behavior of Th and U in the growth and breakdown reactions relevant to actinide-bearing phases (monazite, zircon, thorite, allanite, etc.), and geochemical fractionation processes involving Th and U in fluid interactions. Unfortunately, the measurement of minor and trace concentrations of U in the presence of major concentrations of Th and/or REEs is particularly problematic, especially in complexly zoned phases with large compositional variation on the micro or nanoscale - spatial resolutions now accessible with modern instruments. Sub-micron, high precision compositional analysis of minor components is feasible in very high Z phases where scattering is limited at lower kV (15kV or less) and where the beam diameter can be kept below 400nm at high current (e.g. 200-500nA). High collection efficiency spectrometers and high performance electron optics in EPMA now allow the use of lower overvoltage through an exceptional range in beam current, facilitating higher spatial resolution quantitative analysis. The U LIII edge at 17.2 kV precludes L-series analysis at low kV (high spatial resolution), requiring careful measurements of the actinide M series. Also, U-La detection (wavelength = 0.9A) requires the use of LiF (220) or (420), not generally available on most instruments. Strong peak overlaps of Th on U make highly accurate interference correction mandatory, with problems compounded by the ThMIV and ThMV absorption edges affecting peak, background, and interference calibration measurements (especially the interference of the Th M line family on UMb). Complex REE bearing phases such as monazite, zircon, and allanite have particularly complex interference issues due to multiple peak and background overlaps from elements present in the activation volume, as well as interferences from fluorescence at a distance from adjacent phases or distinct compositional domains in the same phase. Interference corrections for elements detected during boundary fluorescence are further complicated by X-ray focusing geometry considerations. Additional complications arise from the high current densities required for high spatial resolution and high count precision, such as fluctuations in internal charge distribution and peak shape changes as satellite production efficiency varies from calibration to analysis. No flawless method has yet emerged. Extreme care in interference corrections, especially where multiple and sometime mutual overlaps are present, and maximum care (and precision) in background characterization to account for interferences and curvature (e.g., WDS scan or multipoint regression), are crucial developments. Calibration curves from multiple peak and interference calibration measurements at different concentrations, and iterative software methodologies for incorporating absorption edge effects, and non-linearities in interference corrections due to peak shape changes and off-axis X-ray defocussing during boundary fluorescence at a distance, are directions with significant potential.

Are equilibrium multichannel networks predictable? The case of the regulated Indus River, Pakistan

NASA Astrophysics Data System (ADS)

Carling, P. A.; Trieu, H.; Hornby, D. D.; Huang, He Qing; Darby, S. E.; Sear, D. A.; Hutton, C.; Hill, C.; Ali, Z.; Ahmed, A.; Iqbal, I.; Hussain, Z.

2018-02-01

Arguably, the current planform behaviour of the Indus River is broadly predictable. Between Chashma and Taunsa, Pakistan, the Indus is a 264-km-long multiple-channel reach. Remote sensing imagery, encompassing major floods in 2007 and 2010, shows that the Indus has a minimum of two and a maximum of nine channels, with on average four active channels during the dry season and five during the annual monsoon. Thus, the network structure, if not detailed planform, remains stable even for the record 2010 flood (27,100 m3 s- 1; recurrence interval > 100 years). Bankline recession is negligible for discharges less than a peak annual discharge of 6000 m3 s- 1 ( 80% of mean annual flood). The Maximum Flow Efficiency (MFE) principle demonstrates that the channel network is insensitive to the monsoon floods, which typically peak at 13,200 m3 s- 1. Rather, the network is in near-equilibrium with the mean annual flood (7530 m3 s- 1). The MFE principle indicates that stable networks have three to four channels, thus the observed stability in the number of active channels accords with the presence of a near-equilibrium reach-scale channel network. Insensitivity to the annual hydrological cycle demonstrates that the timescale for network adjustment is much longer than the timescale of the monsoon hydrograph, with the annual excess water being stored on floodplains rather than being conveyed in an enlarged channel network. The analysis explains the lack of significant channel adjustment following the largest flood in 40 years and the extensive Indus flooding experienced on an annual basis, with its substantial impacts on the populace and agricultural production.

Maximum density echogram analysis : a novel approach to study the characteristics of oblique echoes observed by MARSIS/Mars Express

NASA Astrophysics Data System (ADS)

P, M.; Narukull, V. R.; Rao, S. V. B.

2017-12-01

The ionograms of the Mars Advance Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument aboard Mars Express spacecraft show vertical and oblique echoes from the Martian ionosphere. The vertical echoes are from the normal ionosphere while the oblique echoes are believed to be from ionization bulges that occur in regions of strong vertical magnetic fields. These oblique echoes appear as downward facing hyperbolas when plotted as radargram (at 1.9 MHz), which is a color coded plot of apparent altitude as a function of time at a single frequency. In order to extract further information from these ionization bulges, we considered the peak density of the oblique echoes and plotted them in a format similar to a radargram and called it as a 'maximum density radargram' (MDR). Thus, an MDR shows the peak densities in entire ionization bulge. This analysis revealed several new aspects of the ionization bulges. We found that there is an asymmetry in the ionization bulge so that the density on one side of the hyperbola is different than the other side. In some cases, the density on the same side of the hyperbola, between the edge and apex, changes. Occasionally, the radargrams show only one side of the hyperbola, while the MDRs show a full hyperbola. When the density structures are repeatedly observed over the same location with a few days interval, the MDR analysis shows that the density inside the bulge varies from one pass to another. Finally, the ionization bulges in the MDR displays are clearly observed on several nights. Several of these nighttime bulges were not apparent in radargram analysis. These observations are discussed in the light of current understanding on the ionization bulges.

Photometry of symbiotic stars. X. EG And, Z And, BF Cyg, CH Cyg, V1329 Cyg, AG Dra, RW Hya, AX Per and IV Vir

NASA Astrophysics Data System (ADS)

Skopal, A.; Vanko, M.; Pribulla, T.; Wolf, M.; Semkov, E.; Jones, A.

2002-04-01

We present new photometric observations of EG And, Z And, BF Cyg, CH Cyg, V1329 Cyg, AG Dra, RW Hya, AX Per and IV Vir made in the standard Johnson UBVR system. The current issue summarizes observations of these objects to 2001 December. The main results can be summarized as follows: EG And: A periodic double-wave variation in all bands as a function of the orbital phase was confirmed. A maximum of the light changes was observed in U (Delta U ~ 0.5 mag). Z And: Our observations cover an active phase, which peaked around 8.4 in U at the beginning of 2000 December. Consequently, a gradual decrease in the star's brightness has been observed. BF Cyg: A periodic wave-like variation in the optical continuum reflects a quiescent phase of this star. A complex light curve (LC) profile was observed. CH Cyg: The recent episode of activity ended in Spring 2000. We determined the position of an eclipse in the outer binary at JD 2451426 +/- 3. Recent observations indicate a slow increase in the star's brightness. V1329 Cyg: Observations were made around a maximum at 2001.2. AG Dra: Our measurements from the Autumn of 2001 revealed a new eruption, which peaked at ~JD 2452217. RW Hya: The light minimum in our mean visual LC precedes the time of the spectroscopic conjunction of the giant in the binary. AX Per: A periodic wave-like variation was observed. Our recent observations revealed a secondary minimum at the orbital phase 0.5, seen best in the V and B bands. IV Vir: The LC displays a double-wave throughout the orbital cycle.

Wave Transformation over a Fringing Coral Reef and the Importance of Low-Frequency Waves and Offshore Water Levels to Runup and Island Overtopping

NASA Astrophysics Data System (ADS)

Cheriton, O. M.; Storlazzi, C. D.; Rosenberger, K. J.

2016-02-01

Low-lying, reef-fringed islands are susceptible to sea-level rise and often subjected to overwash and flooding during large wave events. To quantify wave dynamics and wave-driven water levels on fringing coral reefs, wave gauges and a current meter were deployed for 5 months across two shore-normal transects on Roi-Namur, an atoll island in the Republic of the Marshall Islands. These observations captured two large wave events that had maximum wave heights greater than 6 m and peak periods of 16 s over the fore reef. The larger event coincided with a peak spring tide, leading to energetic, highly-skewed infragravity (0.04-0.004 Hz) and very low frequency (0.004-0.001 Hz) waves at the shoreline, which reached heights of 1.0 and 0.7 m, respectively. Water surface elevations, combined with wave runup, exceeded 3.7 m at the innermost reef flat adjacent to the toe of the beach, resulting in flooding of inland areas. This overwash occurred during a 3-hr time window that coincided with high tide and maximum low-frequency reef flat wave heights. The relatively low-relief characteristics of this narrow reef flat may further drive shoreline amplification of low-frequency waves due to resonance modes. These results demonstrate how the coupling of high offshore water levels with low-frequency reef flat wave energetics can lead to large impacts along atoll and fringing reef-lined shorelines, such as island overwash. These observations lend support to the hypothesis that predicted higher sea levels will lead to more frequent occurrences of both extreme shoreline runup and island overwash, threatening the sustainability of these islands.

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

Li, X; Yang, F

Purpose: Knowing MLC leaf positioning error over the course of treatment would be valuable for treatment planning, QA design, and patient safety. The objective of the current study was to quantify the MLC positioning accuracy for VMAT delivery of head and neck treatment plans. Methods: A total of 837 MLC log files were collected from 14 head and neck cancer patients undergoing full arc VMAT treatment on one Varian Trilogy machine. The actual and planned leaf gaps were extracted from the retrieved MLC log files. For a given patient, the leaf gap error percentage (LGEP), defined as the ratio ofmore » the actual leaf gap over the planned, was evaluated for each leaf pair at all the gantry angles recorded over the course of the treatment. Statistics describing the distribution of the largest LGEP (LLGEP) of the 60 leaf pairs including the maximum, minimum, mean, Kurtosis, and skewness were evaluated. Results: For the 14 studied patients, their PTV located at tonsil, base of tongue, larynx, supraglottis, nasal cavity, and thyroid gland with volume ranging from 72.0 cm{sup 3} to 602.0 cm{sup 3}. The identified LLGEP differed between patients. It ranged from 183.9% to 457.7% with a mean of 368.6%. For the majority of the patients, the LLGEP distributions peaked at non-zero positions and showed no obvious dependence on gantry rotations. Kurtosis and skewness, with minimum/maximum of 66.6/217.9 and 6.5/12.6, respectively, suggested relatively more peaked while right-skewed leaf error distribution pattern. Conclusion: The results indicate pattern of MLC leaf gap error differs between patients of lesion located at similar anatomic site. Understanding the systemic mechanisms underlying these observed error patterns necessitates examining more patient-specific plan parameters in a large patient cohort setting.« less

Observations of wave transformation over a fringing coral reef and the importance of low-frequency waves and offshore water levels to runup, overwash, and coastal flooding

NASA Astrophysics Data System (ADS)

Cheriton, Olivia M.; Storlazzi, Curt D.; Rosenberger, Kurt J.

2016-05-01

Many low-lying tropical islands are susceptible to sea level rise and often subjected to overwash and flooding during large wave events. To quantify wave dynamics and wave-driven water levels on fringing coral reefs, a 5 month deployment of wave gauges and a current meter was conducted across two shore-normal transects on Roi-Namur Island in the Republic of the Marshall Islands. These observations captured two large wave events that had waves with maximum heights greater than 6 m with peak periods of 16 s over the fore reef. The larger event coincided with a peak spring tide, leading to energetic, highly skewed infragravity (0.04-0.004 Hz) and very low frequency (0.004-0.001 Hz) waves at the shoreline, which reached heights of 1.0 and 0.7 m, respectively. Water surface elevations, combined with wave runup, reached 3.7 m above the reef bed at the innermost reef flat adjacent to the toe of the beach, resulting in flooding of inland areas. This overwash occurred during a 3 h time window that coincided with high tide and maximum low-frequency reef flat wave heights. The relatively low-relief characteristics of this narrow reef flat may further drive shoreline amplification of low-frequency waves due to resonance modes. These results (1) demonstrate how the coupling of high offshore water levels with low-frequency reef flat wave energetics can lead to large impacts along fringing reef-lined shorelines, such as island overwash, and (2) lend support to the hypothesis that predicted higher sea levels will lead to more frequent occurrences of these extreme events, negatively impacting coastal resources and infrastructure.

Observations of wave transformation over a fringing coral reef and the importance of low-frequency waves and offshore water levels to runup, overwash, and coastal flooding

USGS Publications Warehouse

Cheriton, Olivia; Storlazzi, Curt; Rosenberger, Kurt

2016-01-01

Many low-lying tropical islands are susceptible to sea level rise and often subjected to overwash and flooding during large wave events. To quantify wave dynamics and wave-driven water levels on fringing coral reefs, a 5 month deployment of wave gauges and a current meter was conducted across two shore-normal transects on Roi-Namur Island in the Republic of the Marshall Islands. These observations captured two large wave events that had waves with maximum heights greater than 6 m with peak periods of 16 s over the fore reef. The larger event coincided with a peak spring tide, leading to energetic, highly skewed infragravity (0.04–0.004 Hz) and very low frequency (0.004–0.001 Hz) waves at the shoreline, which reached heights of 1.0 and 0.7 m, respectively. Water surface elevations, combined with wave runup, reached 3.7 m above the reef bed at the innermost reef flat adjacent to the toe of the beach, resulting in flooding of inland areas. This overwash occurred during a 3 h time window that coincided with high tide and maximum low-frequency reef flat wave heights. The relatively low-relief characteristics of this narrow reef flat may further drive shoreline amplification of low-frequency waves due to resonance modes. These results (1) demonstrate how the coupling of high offshore water levels with low-frequency reef flat wave energetics can lead to large impacts along fringing reef-lined shorelines, such as island overwash, and (2) lend support to the hypothesis that predicted higher sea levels will lead to more frequent occurrences of these extreme events, negatively impacting coastal resources and infrastructure.

Development and modification of a Gaussian and non-Gaussian noise exposure system

NASA Astrophysics Data System (ADS)

Schlag, Adam W.

Millions of people across the world currently have noise induced hearing loss, and many are working in conditions with both continuous Gaussian and non-Gaussian noises that could affect their hearing. It was hypothesized that the energy of the noise was the cause of the hearing loss and did not depend on temporal pattern of a noise. This was referred to as the equal energy hypothesis. This hypothesis has been shown to have limitations though. This means that there is a difference in the types of noise a person receives to induce hearing loss and it is necessary to build a system that can easily mimic various conditions to conduct research. This study builds a system that can produce both non-Gaussian impulse/impact noises and continuous Gaussian noise. It was found that the peak sound pressure level of the system could reach well above the needed 120 dB level to represent acoustic trauma and could replicate well above the 85 dB A-weighted sound pressure level to produce conditions of gradual developing hearing loss. The system reached a maximum of 150 dB sound peak pressure level and a maximum of 133 dB A-weighted sound pressure level. Various parameters could easily be adjusted to control the sound, such as the high and low cutoff frequency to center the sound at 4 kHz. The system build can easily be adjusted to create numerous sound conditions and will hopefully be modified and improved in hopes of eventually being used for animal studies to lead to the creation of a method to treat or prevent noise induced hearing loss.

Magnetostatic interactions in a natural magnetite-ulvospinel intergrowth system

NASA Astrophysics Data System (ADS)

Evans, M. E.; Krasa, D.; Williams, W.; Winklhofer, M.

2005-12-01

The difficult problem of magnetostatic interactions in naturally-occurring minerals has a long history but a renewed attack on it is currently being driven by recent advances in instrumentation and computing power. We report a new investigation of a finely exsolved magnetite/ulvöspinel intergrowth first studied magnetically by Evans & Wayman (1974) and more recently by Harrison et al. (2002). Transmission electron micrographs reveal a rectilinear pattern of tiny magnetite blocks separated by ulvöspinel sheets. The magnetite blocks have a gaussian size distribution with mean and standard deviation of 193 and 46 nm, respectively (n ~ 500), with the separation between nearest neighbours being typically 40 nm, but often much less. Thermomagnetic analysis yields a well-defined Curie point of 548°C indicating that the ``magnetite" actually has a compostion of Fe2.9Ti0.1O4. Routine hysteresis measurements immediately reflect the interaction between neighbouring ``magnetite" regions, with Mrs/Ms = 0.22, well below the expected value for non-interacting single-domain particles. The corresponding FORC diagram clearly reveals the interaction fields with Hi = 30 mT (full-width at half-maximum, FWHM) centred on a well-defined Hc peak at 20 mT. Furthermore, the maximum interaction field observed (~50 mT) agrees well with that expected from simple theory and micromagnetic calculations. Elimination of the intergrowth structure by heating in an evacuated quartz vial for 2 hours at 1000 °C leads to marked changes in the magnetic properties: Mrs/Ms drops to 0.11, Hcr/Hc increases from 1.98 to 2.73, the main peak on the FORC diagram shifts to 6 mT and the interaction field profile drastically narrows (FWHM Hi = 14 mT).

High Power SiGe X-Band (8-10 GHz) Heterojunction Bipolar Transistors and Amplifiers

NASA Technical Reports Server (NTRS)

Ma, Zhenqiang; Jiang, Ningyue; Ponchak, George E.; Alterovitz, Samuel A.

2005-01-01

Limited by increased parasitics and thermal effects as the device size becomes large, current commercial SiGe power HBTs are difficult to operate at X-band (8-12 GHz) with adequate power added efficiencies at high power levels. We found that, by changing the heterostructure and doping profile of SiGe HBTs, their power gain can be significantly improved without resorting to substantial lateral scaling. Furthermore, employing a common-base configuration with proper doping profile instead of a common-emitter configuration improves the power gain characteristics of SiGe HBTs, which thus permits these devices to be efficiently operated at X-band. In this paper, we report the results of SiGe power HBTs and MMIC power amplifiers operating at 8-10 GHz. At 10 GHz, 22.5 dBm (178 mW) RF output power with concurrent gain of 7.32 dB is measured at the peak power-added efficiency of 20.0% and the maximum RF output power of 24.0 dBm (250 mW) is achieved from a 20 emitter finger SiGe power HBT. Demonstration of single-stage X-band medium-power linear MMIC power amplifier is also realized at 8 GHz. Employing a 10-emitter finger SiGe HBT and on-chip input and output matching passive components, a linear gain of 9.7 dB, a maximum output power of 23.4 dBm and peak power added efficiency of 16% is achieved from the power amplifier. The MMIC exhibits very low distortion with third order intermodulation (IM) suppression C/I of -13 dBc at output power of 21.2 dBm and over 20dBm third order output intercept point (OIP3).

Factors affecting the estimate of primary production from space

NASA Technical Reports Server (NTRS)

Balch, W. M.; Byrne, C. F.

1994-01-01

Remote sensing of primary production in the euphotic zone has been based mostly on visible-band and water-leaving radiance measured with the coastal zone color scanner. There are some robust, simple relationships for calculating integral production based on surface measurements, but they also require knowledge for photoadaptive parameters such as maximum photosynthesis which currently cannot be obtained from spave. A 17,000-station data set is used to show that space-based estimates of maximum photosynthesis could improve predictions of psi, the water column light utiliztion index, which is an important term in many primary productivity models. Temperature is also examined as a factor for predicting hydrographic structure and primary production. A simple model is used to relate temperature and maximum photosynthesis; the model incorporates (1) the positive relationship between maximum photosynthesis and temperature and (2) the strongly negative relationship between temperature and nitrate in the ocean (which directly affects maximum growth rates via nitrogen limitation). Since these two factors relate to carbon and nitrogen, 'balanced carbon/nitrogen assimilation' was calculated using the Redfield ratio, It is expected that the relationship between maximum balanced carbon assimilation versus temperature is concave-down, with the peak dependent on nitrate uptake kinetics, temperature-nitrate relationships,a nd the carbon chlorophyll ration. These predictions were compared with the sea truth data. The minimum turnover time for nitrate was also calculated using this approach. Lastly, sea surface temperature gradients were used to predict the slope of isotherms (a proxy for the slope of isopycnals in many waters). Sea truth data show that at size scales of several hundred kilometers, surface temperature gradients can provide information on the slope of isotherms in the top 200 m of the water column. This is directly relevant to the supply of nutrients into the surface mixed layer, which is useful for predicting integral biomass and primary production.

Evaluation of left ventricular performance during supine exercise by transoesophageal M-mode echocardiography in normal subjects.

PubMed Central

Matsumoto, M; Hanrath, P; Kremer, P; Tams, C; Langenstein, B A; Schlüter, M; Weiter, R; Bleifeld, W

1982-01-01

In order to evaluate left ventricular function during dynamic exercise transoesophageal M-mode recordings of the left ventricle were carried out with a newly developed transducer gastroscope system. Twelve healthy subjects performed a graded supine bicycle exercise test. Stable and good quality images of the left ventricle at rest and during exercise at different steps up to a maximum workload of 100 watts were obtained in all patients. Isotonic maximum exercise resulted in a significant increase in fractional shortening of the left ventricle, peak shortening rate, and peak lengthening rate of the left ventricular minor axis. Left ventricular end-diastolic dimension decreased significantly. With increasing workload the pressure rate product increased significantly. It is concluded that transoesophageal M-mode echocardiography is a useful method of evaluating left ventricular performance during dynamic exercise. Images PMID:7082515

A High-Voltage Integrated Circuit Engine for a Dielectrophoresis-based Programmable Micro-Fluidic Processor

PubMed Central

Current, K. Wayne; Yuk, Kelvin; McConaghy, Charles; Gascoyne, Peter R. C.; Schwartz, Jon A.; Vykoukal, Jody V.; Andrews, Craig

2010-01-01

A high-voltage (HV) integrated circuit has been demonstrated to transport droplets on programmable paths across its coated surface. This chip is the engine for a dielectrophoresis (DEP)-based micro-fluidic lab-on-a-chip system. This chip creates DEP forces that move and help inject droplets. Electrode excitation voltage and frequency are variable. With the electrodes driven with a 100V peak-to-peak periodic waveform, the maximum high-voltage electrode waveform frequency is about 200Hz. Data communication rate is variable up to 250kHz. This demonstration chip has a 32×32 array of nominally 100V electrode drivers. It is fabricated in a 130V SOI CMOS fabrication technology, dissipates a maximum of 1.87W, and is about 10.4 mm × 8.2 mm. PMID:23989241

Frequency domain analysis of droplet-based electrostatic transducers

NASA Astrophysics Data System (ADS)

Allegretto, Graham; Dobashi, Yuta; Dixon, Katelyn; Wyss, Justin; Yao, Dickson; Madden, John D. W.

2018-07-01

Squeezing a water droplet between two electrodes can generate a potential difference by converting some of the mechanical energy in vibrations into electrical energy. By utilizing the high capacitance inherent to electric double layers, and the surface charging at a polymer/water interface, we demonstrate a sensor that generates up to 892 mV peak-to-peak between 1 and 100 Hz, in response to a 250 μm deformation. This frequency response is described and explained using a linearized model in which the interfacial charge acts as the priming voltage, removing the need for external charging normally required in capacitive generators. The model suggests how to design the cell for maximum power output and provides an intuitive understanding of the high pass nature of the sensor. It successfully predicts the point of maximum power transfer.

Optimum Suction Distribution for Transition Control

NASA Technical Reports Server (NTRS)

Balakumar, P.; Hall, P.

1996-01-01

The optimum suction distribution which gives the longest laminar region for a given total suction is computed. The goal here is to provide the designer with a method to find the best suction distribution subject to some overall constraint applied to the suction. We formulate the problem using the Lagrangian multiplier method with constraints. The resulting non-linear system of equations is solved using the Newton-Raphson technique. The computations are performed for a Blasius boundary layer on a flat-plate and crossflow cases. For the Blasius boundary layer, the optimum suction distribution peaks upstream of the maximum growth rate region and remains flat in the middle before it decreases to zero at the end of the transition point. For the stationary and travelling crossflow instability, the optimum suction peaks upstream of the maximum growth rate region and decreases gradually to zero.