48 CFR 1816.405-271 - Base fee.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... For other contracts, such as those for hardware or software development, the procurement officer may... during the life of the contract at defined intervals on a provisional basis. If the final award fee...

48 CFR 1816.405-271 - Base fee.

Code of Federal Regulations, 2012 CFR

2012-10-01

.... For other contracts, such as those for hardware or software development, the procurement officer may... during the life of the contract at defined intervals on a provisional basis. If the final award fee...

48 CFR 1816.405-271 - Base fee.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... For other contracts, such as those for hardware or software development, the procurement officer may... during the life of the contract at defined intervals on a provisional basis. If the final award fee...

Monitoring of the alignment in developing tissue-engineered constructs by elastic scattering spectroscopy

NASA Astrophysics Data System (ADS)

Kostyuk, Oksana P.; Brown, Robert A.

2004-07-01

Elastic light scattering spectroscopy was applied to monitor the development of alignment in fibroblast-populated collagen gels. Gels were seeded with human dermal fibroblasts in rectangular moulds so uniaxial tension was generated in the central zone of the gels due to cell contraction. There was a gradual transition from a disorganized matrix with round cells to highly organized cell/collagen matrix, aligned in the direction of the principal strain developed during gel contraction (observed with light microscopy under phase contrast). Spectra of the backscattered light (320 - 850 nm) were acquired via an optical probe with 2.75-mm source-detector separation, positioned perpendicularly to the gel surface, at 0, 17, 24, 41, 47, 65 and 72h. Spectra were registered for light propagating along, perpendicular and at intermediate angles relative to the cell/collagen matrix alignment, at 45° intervals. Backscatter was isotropic for non-contracted gels. However, as gels contracted, anisotropy of backscatter gradually increased. This was characterized by an 'anisotropy factor,' AF (500 nm), calculated as the ratio of backscatter intensities at 90° and 0° positions of the probe, at 500 nm. AF (500nm) increased from 1.2 +/- 0.1 at 0h up to 2.6 +/- 0.4 at 72h of contraction, with more backscatter detected perpendicular to the cell/collagen matrix alignment than in parallel direction. Thus, backscatter anisotropy allows determination of the direction of the preferential alignment and quantitative monitoring of its development during gel contraction. It is possible to use measurements of this type to quantify a proportion of oriented fibrils in the gel using modeling.

Motor Unit Interpulse Intervals During High Force Contractions.

PubMed

Stock, Matt S; Thompson, Brennan J

2016-01-01

We examined the means, medians, and variability for motor-unit interpulse intervals (IPIs) during voluntary, high force contractions. Eight men (mean age = 22 years) attempted to perform isometric contractions at 90% of their maximal voluntary contraction force while bipolar surface electromyographic (EMG) signals were detected from the vastus lateralis and vastus medialis muscles. Surface EMG signal decomposition was used to determine the recruitment thresholds and IPIs of motor units that demonstrated accuracy levels ≥ 96.0%. Motor units with high recruitment thresholds demonstrated longer mean IPIs, but the coefficients of variation were similar across all recruitment thresholds. Polynomial regression analyses indicated that for both muscles, the relationship between the means and standard deviations of the IPIs was linear. The majority of IPI histograms were positively skewed. Although low-threshold motor units were associated with shorter IPIs, the variability among motor units with differing recruitment thresholds was comparable.

Generation of poleward moving auroral forms (PMAFs) during periods of dayside auroral oval expansions/contractions and periods when the dayside auroral oval is expanded and stable

NASA Astrophysics Data System (ADS)

Fasel, G. J.; Flicker, J.; Sibeck, D. G.; Alyami, M.; Angelo, A.; Aylward, R. J.; Bender, S.; Christensen, M.; Kim, J.; Kristensen, H.; Orellana, Y.; Sahin, O.; Yoon, J.; Green, D.; Sigernes, F.; Lorentzen, D. A.

2013-12-01

The latitude of the equatorial edge of the dayside auroral oval has been shown to vary with the direction of the IMF Bz-component. The equatorward/poleward edge of the dayside auroral oval shifts equatorward/poleward when the IMF Bz-component is negative/positive [Burch, 1973; Akasofu, 1977; Horwitz and Akasofu, 1977; Sandholt et al., 1986, 1988]. Past studies have shown that poleward-moving auroral forms (PMAFs) are a common feature during equatorward expansions of the dayside auroral oval. Horwitz and Akasofu [1977] noted a one-to-one correspondence of luminous PMAFs associated with an equatorward expansion of the dayside auroral oval. During the southward turning of the IMF Bz-component the merging rate on the dayside increases [Newell and Meng, 1987] leading to the erosion of the dayside magnetopause. The field line merging process is thought to be most efficient when the interplanetary magnetic field (IMF) Bz-component turns southward. Both Vorobjev et al. [1975] and Horwitz and Akasofu [1977] attributed these PMAFs to magnetic flux being eroded away from the dayside magnetopause and transported antisunward. Dayside poleward-moving auroral forms are also observed during periods of an expanded and stable dayside auroral oval for both northern and southern hemisphere observations [Sandholt et al., 1986, 1989, 1990; Rairden and Mende, 1989; Mende et al., 1990]. Poleward-moving auroral forms have also been observed during some dayside oval contractions but have not been discussed much in the literature. This study examines the dayside auroral oval during periods of expansion, contraction, and during periods of an expanded and stable dayside auroral oval. This statistical study will provide the following results: number of poleward-moving auroral forms that are generated during dayside auroral oval expansions/contractions and during periods of a stable and expanded dayside auroral oval, the average initial and final elevation angle of the dayside auroral oval, time for dayside auroral oval to expand or contract, and the solar wind parameters (IMF Bx, By, Bz, speed, and pressure) associated with each interval (expansion, contraction, or stable and expanded).

Mechanomyography-Based Wearable Monitor of Quasi-Isometric Muscle Fatigue for Motor Neural Prostheses.

PubMed

Krueger, Eddy; Popović-Maneski, Lana; Nohama, Percy

2018-02-01

A motor neural prosthesis based on surface functional electrical stimulation (sFES) can restore functional movement (e.g., standing, walking) in patients with a spinal cord injury (SCI). sFES generates muscle contractions in antigravity muscles and allows balance-assisted standing. This induced standing has several benefits, such as improved cardiovascular function, decreased incidence of urinary infections, reduced joint contractures, and muscle atrophy. The duration of sFES assisted standing is limited due to the quick onset of muscle fatigue. Currently, there is no method available to reliably estimate real-time muscle fatigue during sFES. Simply monitoring the M-wave changes is not suitable due to the high signal disturbances that arise during multi-channel electrical stimulation. Mechanomyography (MMG) is immune to electrical stimulation artifacts and can be used to detect subtle vibrations on the surface of the skin related to activation of the underlying muscle's motor units (MU). The aim of this study was to develop a method for detecting muscle fatigue brought on by sFES. The method was tested in three different heads of the quadriceps muscle in SCI patients during electrically elicited quasi-isometric contraction. Six spinal cord-injured male volunteers, with no voluntary control of the quadriceps muscle participated in the study. Electrical bursts of voltage-controlled monophasic square pulses at frequencies of 1 kHz (50% duty cycle) at 50 Hz (15% duty cycle) were used to generate thigh muscle contractions that controlled the knee joint in the sagittal plane. The pulse amplitudes were set to position the knee joint at a 5° angle from the horizontal plane and when the knee angle dropped to 20° (e.g., the quadriceps were unable to hold the lower leg in the desired position), the test was terminated. Two data segments lasting 10 s each, at the beginning and end of each test, were analyzed. The muscle contraction was assessed by MMG sensors positioned on the rectus femoris, vastus lateralis, and vastus medialis muscles. Data segments were decomposed into 11 frequency bands using a Cauchy wavelet transform. In the initial time interval (non-fatigued muscle), the power peak was concentrated in the 11.31 Hz frequency band. In the final interval (muscle fatigued) this peak shifted to lower frequencies (2 and 6 Hz frequency bands). The decreased frequency was most prominent during the last 4 s of the recordings. It was shown that MMG could be used as a real-time indicator of muscle fatigue during FES-induced isometric contraction of quadriceps; hence, MMG could be used in closed-loop control as a fatigue detector. Subsequent studies for non-isometric contractions could possibly lead to prediction of muscle fatigue before contractile failure during functional use of the muscle. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

7 CFR 1726.125 - Generating plant facilities.

Code of Federal Regulations, 2011 CFR

2011-01-01

... buildings are covered under subpart E of this part. (a) Contract forms. (1) The borrower must use RUS Form... RUS Form 200, Construction Contract—Generating, for generating project construction contracts in the.... (3) The borrower may, in its discretion, use other contract or written purchase order forms for those...

7 CFR 1726.125 - Generating plant facilities.

Code of Federal Regulations, 2010 CFR

2010-01-01

... buildings are covered under subpart E of this part. (a) Contract forms. (1) The borrower must use RUS Form... RUS Form 200, Construction Contract—Generating, for generating project construction contracts in the.... (3) The borrower may, in its discretion, use other contract or written purchase order forms for those...

7 CFR 1726.125 - Generating plant facilities.

Code of Federal Regulations, 2014 CFR

2014-01-01

... buildings are covered under subpart E of this part. (a) Contract forms. (1) The borrower shall use RUS Form... RUS Form 200, Construction Contract—Generating, for generating project construction contracts in the.... (3) The borrower may, in its discretion, use other contract forms or written purchase order forms for...

7 CFR 1726.125 - Generating plant facilities.

Code of Federal Regulations, 2012 CFR

2012-01-01

... buildings are covered under subpart E of this part. (a) Contract forms. (1) The borrower must use RUS Form... RUS Form 200, Construction Contract—Generating, for generating project construction contracts in the.... (3) The borrower may, in its discretion, use other contract or written purchase order forms for those...

7 CFR 1726.125 - Generating plant facilities.

Code of Federal Regulations, 2013 CFR

2013-01-01

... buildings are covered under subpart E of this part. (a) Contract forms. (1) The borrower shall use RUS Form... RUS Form 200, Construction Contract—Generating, for generating project construction contracts in the.... (3) The borrower may, in its discretion, use other contract forms or written purchase order forms for...

Measurement of high-resolution mechanical contraction of cardiac muscle by induced eddy current.

PubMed

Lee, Young-Jae; Lee, Kang-Hwi; Kang, Seung-Jin; Kim, Kyeung-Nam; Khang, Seonah; Koo, Hye Ran; Gi, Sunok; Lee, Joo Hyeon; Lee, Jeong-Whan

2014-01-01

There are many types of devices which help to manage a personal health conditions such as heartbeat chest belt, pedometer and smart watch. And the most common device has the relationship with heart rate or ECG data. However, users have to attach some electrode or fasten the belt on the bare skin to measure bio-signal information. Therefore, most of people want more convenient and short-ready-time and no-need to attach electrode. In this paper, we proposed the high-resolution measuring system of mechanical activity of cardiac muscle and thereby measure heartbeat. The principle of the proposed measuring method is that the alternating current generate alternating magnetic field around coil. This primary magnetic field induces eddy current which makes magnetic field against primary coil in the nearby objects. To measure high-resolution changes of the induced secondary magnetic fields, we used digital Phase-locked loop(PLL) circuit which provides more high-resolution traces of frequency changes than the previous studies based on digital frequency counter method. As a result of our preliminary experiment, peak-peak intervals of the proposed method showed high correlation with R-R intervals of clinical ECG signals(r=0.9249). Also, from signal traces of the proposed method, we might make a conjecture that the contraction of atrium or ventricle is reflected by changing conductivity of cardiac muscle which is beating ceaselessly.

Dynamics of myosin-driven skeletal muscle contraction: I. Steady-state force generation.

PubMed

Lan, Ganhui; Sun, Sean X

2005-06-01

Skeletal muscle contraction is a canonical example of motor-driven force generation. Despite the long history of research in this topic, a mechanistic explanation of the collective myosin force generation is lacking. We present a theoretical model of muscle contraction based on the conformational movements of individual myosins and experimentally measured chemical rate constants. Detailed mechanics of the myosin motor and the geometry of the sarcomere are taken into account. Two possible scenarios of force generation are examined. We find only one of the scenarios can give rise to a plausible contraction mechanism. We propose that the synchrony in muscle contraction is due to a force-dependent ADP release step. Computational results of a half sarcomere with 150 myosin heads can explain the experimentally measured force-velocity relationship and efficiency data. We predict that the number of working myosin motors increases as the load force is increased, thus showing synchrony among myosin motors during muscle contraction. We also find that titin molecules anchoring the thick filament are passive force generators in assisting muscle contraction.

Dynamics of Myosin-Driven Skeletal Muscle Contraction: I. Steady-State Force Generation

PubMed Central

Lan, Ganhui; Sun, Sean X.

2005-01-01

Skeletal muscle contraction is a canonical example of motor-driven force generation. Despite the long history of research in this topic, a mechanistic explanation of the collective myosin force generation is lacking. We present a theoretical model of muscle contraction based on the conformational movements of individual myosins and experimentally measured chemical rate constants. Detailed mechanics of the myosin motor and the geometry of the sarcomere are taken into account. Two possible scenarios of force generation are examined. We find only one of the scenarios can give rise to a plausible contraction mechanism. We propose that the synchrony in muscle contraction is due to a force-dependent ADP release step. Computational results of a half sarcomere with 150 myosin heads can explain the experimentally measured force-velocity relationship and efficiency data. We predict that the number of working myosin motors increases as the load force is increased, thus showing synchrony among myosin motors during muscle contraction. We also find that titin molecules anchoring the thick filament are passive force generators in assisting muscle contraction. PMID:15778440

Pacific Northwest GridWise™ Testbed Demonstration Projects; Part I. Olympic Peninsula Project

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

Hammerstrom, Donald J.; Ambrosio, Ron; Carlon, Teresa A.

2008-01-09

This report describes the implementation and results of a field demonstration wherein residential electric water heaters and thermostats, commercial building space conditioning, municipal water pump loads, and several distributed generators were coordinated to manage constrained feeder electrical distribution through the two-way communication of load status and electric price signals. The field demonstration took place in Washington and Oregon and was paid for by the U.S. Department of Energy and several northwest utilities. Price is found to be an effective control signal for managing transmission or distribution congestion. Real-time signals at 5-minute intervals are shown to shift controlled load in time.more » The behaviors of customers and their responses under fixed, time-of-use, and real-time price contracts are compared. Peak loads are effectively reduced on the experimental feeder. A novel application of portfolio theory is applied to the selection of an optimal mix of customer contract types.« less

Exposure to Radiofrequency Radiation Emitted from Common Mobile Phone Jammers Alters the Pattern of Muscle Contractions: an Animal Model Study.

PubMed

Rafati, A; Rahimi, S; Talebi, A; Soleimani, A; Haghani, M; Mortazavi, S M J

2015-09-01

The rapid growth of wireless communication technologies has caused public concerns regarding the biological effects of electromagnetic radiations on human health. Some early reports indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians such as the alterations of the pattern of muscle extractions. This study is aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted from mobile phone jammers on the pulse height of contractions, the time interval between two subsequent contractions and the latency period of frog's isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz). Frogs were kept in plastic containers in a room. Animals in the jammer group were exposed to radiofrequency (RF) radiation emitted from a common Jammer at a distance of 1m from the jammer's antenna for 2 hours while the control frogs were only sham exposed. Then animals were sacrificed and isolated gastrocnemius muscles were exposed to on/off jammer radiation for 3 subsequent 10 minute intervals. Isolated gastrocnemius muscles were attached to the force transducer with a string. Using a PowerLab device (26-T), the pattern of muscular contractions was monitored after applying single square pulses of 1V (1 Hz) as stimuli. The findings of this study showed that the pulse height of muscle contractions could not be affected by the exposure to electromagnetic fields. However, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions.

Polypyrrole-chitosan conductive biomaterial synchronizes cardiomyocyte contraction and improves myocardial electrical impulse propagation.

PubMed

Cui, Zhi; Ni, Nathan C; Wu, Jun; Du, Guo-Qing; He, Sheng; Yau, Terrence M; Weisel, Richard D; Sung, Hsing-Wen; Li, Ren-Ke

2018-01-01

Background: The post-myocardial infarction (MI) scar interrupts electrical impulse propagation and delays regional contraction, which contributes to ventricular dysfunction. We investigated the potential of an injectable conductive biomaterial to restore scar tissue conductivity and re-establish synchronous ventricular contraction. Methods: A conductive biomaterial was generated by conjugating conductive polypyrrole (PPY) onto chitosan (CHI) backbones. Trypan blue staining of neonatal rat cardiomyocytes (CMs) cultured on biomaterials was used to evaluate the biocompatibility of the conductive biomaterials. Ca 2+ imaging was used to visualize beating CMs. A cryoablation injury rat model was used to investigate the ability of PPY:CHI to improve cardiac electrical propagation in the injured heart in vivo . Electromyography was used to evaluate conductivity of scar tissue ex vivo . Results: Cell survival and morphology were similar between cells cultured on biomaterials-coated and uncoated-control dishes. PPY:CHI established synchronous contraction of two distinct clusters of spontaneously-beating CMs. Intramyocardial PPY:CHI injection into the cryoablation-induced injured region improved electrical impulse propagation across the scarred tissue and decreased the QRS interval, whereas saline- or CHI-injected hearts continued to have delayed propagation patterns and significantly reduced conduction velocity compared to healthy controls. Ex vivo evaluation found that scar tissue from PPY:CHI-treated rat hearts had higher signal amplitude compared to those from saline- or CHI-treated rat heart tissue. Conclusions: The PPY:CHI biomaterial is electrically conductive, biocompatible and injectable. It improved synchronous contraction between physically separated beating CM clusters in vitro . Intra-myocardial injection of PPY:CHI following cardiac injury improved electrical impulse propagation of scar tissue in vivo .

Effect of short-term hypothyroidism on reproduction in the bitch.

PubMed

Panciera, D L; Purswell, B J; Kolster, K A

2007-08-01

Hypothyroidism in bitches has been reported to cause a variable interestrus interval, infertility, abortion, and stillbirth. The objective of this study was to evaluate the effect of experimentally induced hypothyroidism in bitches on fertility, pregnancy, parturition, and neonatal health. Eighteen healthy multiparous bitches were used; hypothyroidism was induced (by radioiodine administration) in nine bitches and the remaining nine served as untreated controls. After breeding, bitches were evaluated for pregnancy, fetal resorption, gestation length, litter size, duration and strength of uterine contractions (during parturition), interval between delivery of pups, viability of pups at birth, periparturient survival, and weight of pups at birth through 4 weeks of age. Bitches were bred a median of 19 weeks after induction of hypothyroidism. All bitches became pregnant and delivered term litters. There was no difference in the interestrus interval, litter size, or gestation length between hypothyroid and control bitches. Duration of uterine contractions was longer, but contraction strength was weaker in hypothyroid than control bitches; however, the interval between delivery of pups was not affected. Periparturient puppy mortality was significantly higher in litters from hypothyroid bitches. Viability scores and weight at birth were significantly lower in pups from hypothyroid bitches than controls. There was no difference between groups in pup weight gain during the first 4 weeks, in the interval from birth to the eyes opened, or to the onset of walking. Although hypothyroidism of relatively short duration did not affect fertility, it prolonged parturition and reduced pup survival in the periparturient period.

The pacemaker activity generating the intrinsic myogenic contraction of the dorsal vessel of Tenebrio molitor (Coleoptera).

PubMed

Markou, T; Theophilidis, G

2000-11-01

Combined intracellular and extracellular recordings from various parts of the isolated dorsal vessel of Tenebrio molitor revealed some of the following electrophysiological properties of the heart and the aorta. (i) The wave of depolarization causing forward pulsation of the dorsal vessel was always transmitted from posterior to anterior, with a conduction velocity of 0.014 m s(-1) in the heart and 0.001 m s(-1) in the aorta when the heart rate was 60 beats min(-1). (ii) There was no pacemaker activity in the aorta. (iii) The duration of the compound action potential in the aortic muscle depended on the duration of the pacemaker action potential generated in the heart. (iv) Isolated parts of the heart continued to contract rhythmically for hours, indicating powerful pacemaker activity in individual cardiac segments. (v) There was a direct relationship between action potential duration and the length of the preceding diastolic interval. (vi) The rhythmic wave of depolarization was dependent on the influx of Ca(2+). (vii) The recovery of the electrical properties of myocardial cells that had been disrupted by sectioning was rapid. (viii) In hearts sectioned into two halves, the rhythmic pacemaker action potentials recorded simultaneously from the two isolated halves eventually drifted out of phase, but they had the same intrinsic frequency. In the light of these data, we discuss two alternative models for the generation of spontaneous rhythmic pumping movements of the heart and aorta.

Microprocessor controlled movement of solid colonic content using sequential neural electrical stimulation

PubMed Central

Amaris, M A; Rashev, P Z; Mintchev, M P; Bowes, K L

2002-01-01

Background and aims: Invoked peristaltic contractions and movement of solid content have not been attempted in normal canine colon. The purpose of this study was to determine if movement of solid content through the colon could be produced by microprocessor controlled sequential stimulation. Methods: The study was performed on six anaesthetised dogs. At laparotomy, a 15 cm segment of descending colon was selected, the proximal end closed with a purse string suture, and the distal end opened into a collecting container. Four sets of subserosal stimulating electrodes were implanted at 3 cm intervals. The segment of bowel was filled with a mixture of dog food and 50 plastic pellets before each of 2–5 random sessions of non-stimulated or stimulated emptying. Propagated contractions were generated using microprocessor controlled bipolar trains of 50 Hz rectangular voltage having 20 V (peak to peak) amplitude, 18 second stimulus duration, and a nine second phase lag between stimulation trains in sequential electrode sets. Results: Electrical stimulation using the above mentioned parameters resulted in powerful phasic contractions that closed the lumen. By phase locking the stimulation voltage between adjacent sets of electrodes, propagated contractions could be produced in an aboral or orad direction. The number of evacuated pellets during the stimulation sessions was significantly higher than during the non-stimulated sessions (p<0.01). Conclusions: Microprocessor controlled electrical stimulation accelerated movement of colonic content suggesting the possibility of future implantable colonic stimulators. PMID:11889065

Intravenous or local injections of flavoxate in the rostral pontine reticular formation inhibit urinary frequency induced by activation of medial frontal lobe neurons in rats.

PubMed

Sugaya, Kimio; Nishijima, Saori; Kadekawa, Katsumi; Ashitomi, Katsuhiro; Ueda, Tomoyuki; Yamamoto, Hideyuki

2014-10-01

The rostral pontine reticular formation has a strong inhibitory effect on micturition by facilitating lumbosacral glycinergic neurons. We assessed the influence of the rostral pontine reticular formation on the micturition reflex after noradrenaline injection in the medial frontal lobe. We also examined the relation between the medial frontal lobe and the rostral pontine reticular formation. Continuous cystometry was performed in 28 female rats. After the interval between bladder contractions was shortened by noradrenaline injection in the medial frontal lobe we injected glutamate or flavoxate hydrochloride in the rostral pontine reticular formation or intravenously injected flavoxate or propiverine. The change in bladder activity was examined. Noradrenaline injection in the medial frontal lobe shortened the interval between bladder contractions. In contrast to the bladder contraction interval before and after noradrenaline injection in the medial frontal lobe, the interval was prolonged after noradrenaline injection when glutamate or flavoxate was injected in the rostral pontine reticular formation, or flavoxate was injected intravenously. Noradrenaline injection in the medial frontal lobe plus intravenous propiverine injection also prolonged the interval compared to that after noradrenaline injection alone. However, the interval after noradrenaline injection in the medial frontal lobe plus intravenous injection of propiverine was shorter than that before noradrenaline injection only. Medial frontal lobe neurons excited by noradrenaline may facilitate the micturition reflex via activation of inhibitory interneurons, which inhibit descending rostral pontine reticular formation neurons that innervate the lumbosacral glycinergic inhibitory neurons. Therefore, the mechanism of micturition reflex facilitation by the activation of medial frontal lobe neurons involves the rostral pontine reticular formation. Copyright © 2014 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Electrically induced contraction levels of the quadriceps femoris muscles in healthy men: the effects of three patterns of burst-modulated alternating current and volitional muscle fatigue.

PubMed

Parker, Michael G; Broughton, Alex J; Larsen, Ben R; Dinius, Josh W; Cimbura, Mac J; Davis, Matthew

2011-12-01

The purpose of this study was to compare electrically induced contraction levels produced by three patterns of alternating current in fatigued and nonfatigued skeletal muscles. Eighteen male volunteers without health conditions, with a mean (SD) age of 24.9 (3.4) yrs were randomly exposed to a fatiguing volitional isometric quadriceps contraction and one of three patterns of 2.5-KHz alternating current; two were modulated at 50 bursts per second (10% burst duty cycle with five cycles per burst and 90% burst duty cycle with 45 cycles per burst), and one pattern was modulated at 100 bursts per second (10% burst duty cycle with 2.5 cycles per burst). The electrically induced contraction levels produced by the three patterns of electrical stimulation were compared before and after the fatiguing contraction. The 10% burst duty cycles produced 42.9% (95% confidence interval, 29.1%-56.7%) and 32.1% (95% confidence interval, 18.2%-45.9%) more muscle force (P < 0.001) than did the 90% burst duty cycle pattern. There was no significant interaction effect (P = 0.392) of electrical stimulation patterns and fatigue on the electrically induced contraction levels. The lower burst duty cycle (10%) patterns of electrical stimulation produced stronger muscle contractions. Furthermore, the stimulation patterns had no influence on the difference in muscle force before and after the fatiguing quadriceps contraction. Consequently, for clinical applications in which high forces are desired, the patterns using the 10% burst duty cycle may be helpful.

Career Stage and Generational Differences in Psychological Contracts

ERIC Educational Resources Information Center

Hess, Narelle; Jepsen, Denise M.

2009-01-01

Purpose: The purpose of this paper is to determine how employees in different generational groups (or cohorts) and different career stages perceive their psychological contracts. Design/methodology/approach: A survey of 345 working adults included psychological contract obligations, incentives and importance and the cognitive responses of job…

Survey of the Effects of Exposure to 900 MHz Radiofrequency Radiation Emitted by a GSM Mobile Phone on the Pattern of Muscle Contractions in an Animal Model.

PubMed

Mortazavi, S M J; Rahimi, S; Talebi, A; Soleimani, A; Rafati, A

2015-09-01

The rapid development of wireless telecommunication technologies over the past decades, has led to significant changes in the exposure of the general public to electromagnetic fields. Nowadays, people are continuously exposed to different sources of electromagnetic fields such as mobile phones, mobile base stations, cordless phones, Wi-Fi routers, and power lines. Therefore, the last decade witnessed a rapidly growing concern about the possible health effects of exposure to electromagnetic fields emitted by these sources. In this study that was aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted by a GSM mobile phone on the pattern of contraction in frog's isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz), pulse height of contractions, the time interval between two subsequent contractions and the latency period were measured. Our findings showed that the pulse height of contractions muscle could be affected by the exposure to electromagnetic fields. Especially, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions.

Exposure to Radiofrequency Radiation Emitted from Common Mobile Phone Jammers Alters the Pattern of Muscle Contractions: an Animal Model Study

PubMed Central

Rafati, A.; Rahimi, S.; Talebi, A.; Soleimani, A.; Haghani, M.; Mortazavi, S. M. J.

2015-01-01

Introduction The rapid growth of wireless communication technologies has caused public concerns regarding the biological effects of electromagnetic radiations on human health. Some early reports indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians such as the alterations of the pattern of muscle extractions. This study is aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted from mobile phone jammers on the pulse height of contractions, the time interval between two subsequent contractions and the latency period of frog’s isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz). Materials and Methods Frogs were kept in plastic containers in a room. Animals in the jammer group were exposed to radiofrequency (RF) radiation emitted from a common Jammer at a distance of 1m from the jammer’s antenna for 2 hours while the control frogs were only sham exposed. Then animals were sacrificed and isolated gastrocnemius muscles were exposed to on/off jammer radiation for 3 subsequent 10 minute intervals. Isolated gastrocnemius muscles were attached to the force transducer with a string. Using a PowerLab device (26-T), the pattern of muscular contractions was monitored after applying single square pulses of 1V (1 Hz) as stimuli. Results The findings of this study showed that the pulse height of muscle contractions could not be affected by the exposure to electromagnetic fields. However, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. Conclusion These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions. PMID:26396969

Advanced Computational Methods for Optimization of Non-Periodic Inspection Intervals for Aging Infrastructure

DTIC Science & Technology

2017-01-05

AFRL-AFOSR-JP-TR-2017-0002 Advanced Computational Methods for Optimization of Non-Periodic Inspection Intervals for Aging Infrastructure Manabu...Computational Methods for Optimization of Non-Periodic Inspection Intervals for Aging Infrastructure 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386...UNLIMITED: PB Public Release 13. SUPPLEMENTARY NOTES 14. ABSTRACT This report for the project titled ’Advanced Computational Methods for Optimization of

Reduction of construction wastes by improving construction contract management: a multinational evaluation.

PubMed

Mendis, Daylath; Hewage, Kasun N; Wrzesniewski, Joanna

2013-10-01

The Canadian construction industry generates 30% of the total municipal solid waste deposited in landfills. Ample evidence can be found in the published literature about rework and waste generation due to ambiguity and errors in contract documents. Also, the literature quotes that disclaimer clauses in contract documents are included in the contractual agreements to prevent contractor claims, which often cause rework. Our professional practice has also noted that there are several disclaimer clauses in standard contract documents which have the potential to cause rework (and associated waste). This article illustrates a comparative study of standard contractual documents and their potential to create rework (and associated waste) in different regions of the world. The objectives of this study are (1) to analyse standard contractual documents in Canada, the USA and Australia in terms of their potential to generate rework and waste, and (2) to propose changes/amendments to the existing standard contract documents to minimise/avoid rework. In terms of construction waste management, all the reviewed standard contract documents have deficiencies. The parties that produce the contract documents include exculpatory clauses to avoid the other party's claims. This approach tends to result in rework and construction waste. The contractual agreements/contract documents should be free from errors, deficiencies, ambiguity and unfair risk transfers to minimise/avoid potential to generate rework and waste.

Reducing composite restoration polymerization shrinkage stress through resin modified glass-ionomer based adhesives.

PubMed

Naoum, S J; Mutzelburg, P R; Shumack, T G; Thode, Djg; Martin, F E; Ellakwa, A E

2015-12-01

The aim of this study was to determine whether employing resin modified glass-ionomer based adhesives can reduce polymerization contraction stress generated at the interface of restorative composite adhesive systems. Five resin based adhesives (G Bond, Optibond-All-in-One, Optibond-Solo, Optibond-XTR and Scotchbond-Universal) and two resin modified glass-ionomer based adhesives (Riva Bond-LC, Fuji Bond-LC) were analysed. Each adhesive was applied to bond restorative composite Filtek-Z250 to opposing acrylic rods secured within a universal testing machine. Stress developed at the interface of each adhesive-restorative composite system (n = 5) was calculated at 5-minute intervals over 6 hours. The resin based adhesive-restorative composite systems (RBA-RCS) demonstrated similar interface stress profiles over 6 hours; initial rapid contraction stress development (0-300 seconds) followed by continued contraction stress development ≤0.02MPa/s (300 seconds - 6 hours). The interface stress profile of the resin modified glass-ionomer based adhesive-restorative composite systems (RMGIBA-RCS) differed substantially to the RBA-RCS in several ways. Firstly, during 0-300 seconds the rate of contraction stress development at the interface of the RMGIBA-RCS was significantly (p < 0.05) lower than at the interface of the RBA-RCS. Secondly, at 300 seconds and 6 hours the interface contraction stress magnitude of the RMGIBA-RCS was significantly (p < 0.05) lower than the stress of all assessed RBA-RCS. Thirdly, from 300 seconds to 6 hours both the magnitude and rate of interface stress of the RMGIBA-RCS continued to decline over the 6 hours from the 300 seconds peak. The use of resin modified glass-ionomer based adhesives can significantly reduce the magnitude and rate of polymerization contraction stress developed at the interface of adhesive-restorative composite systems. © 2015 Australian Dental Association.

Implantable power generation system utilizing muscle contractions excited by electrical stimulation.

PubMed

Sahara, Genta; Hijikata, Wataru; Tomioka, Kota; Shinshi, Tadahiko

2016-06-01

An implantable power generation system driven by muscle contractions for supplying power to active implantable medical devices, such as pacemakers and neurostimulators, is proposed. In this system, a muscle is intentionally contracted by an electrical stimulation in accordance with the demands of the active implantable medical device for electrical power. The proposed system, which comprises a small electromagnetic induction generator, electrodes with an electrical circuit for stimulation and a transmission device to convert the linear motion of the muscle contractions into rotational motion for the magneto rotor, generates electrical energy. In an ex vivo demonstration using the gastrocnemius muscle of a toad, which was 28 mm in length and weighed 1.3 g, the electrical energy generated by the prototype exceeded the energy consumed for electrical stimulation, with the net power being 111 µW. It was demonstrated that the proposed implantable power generation system has the potential to replace implantable batteries for active implantable medical devices. © IMechE 2016.

Survey of the Effects of Exposure to 900 MHz Radiofrequency Radiation Emitted by a GSM Mobile Phone on the Pattern of Muscle Contractions in an Animal Model

PubMed Central

Mortazavi, S. M. J.; Rahimi, S.; Talebi, A.; Soleimani, A.; Rafati, A.

2015-01-01

Background: The rapid development of wireless telecommunication technologies over the past decades, has led to significant changes in the exposure of the general public to electromagnetic fields. Nowadays, people are continuously exposed to different sources of electromagnetic fields such as mobile phones, mobile base stations, cordless phones, Wi-Fi routers, and power lines. Therefore, the last decade witnessed a rapidly growing concern about the possible health effects of exposure to electromagnetic fields emitted by these sources. Materials and Methods: In this study that was aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted by a GSM mobile phone on the pattern of contraction in frog’s isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz), pulse height of contractions, the time interval between two subsequent contractions and the latency period were measured. Results: Our findings showed that the pulse height of contractions muscle could be affected by the exposure to electromagnetic fields. Especially, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. Conclusion: These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions. PMID:26396968

Comparison between Measurements Obtained with three Different Perineometers

PubMed Central

Barbosa, Patrícia Brentegani; Franco, Maíra Menezes; de Oliveira Souza, Flaviane; Antônio, Flávia Ignácio; Montezuma, Thaís; Ferreira, Cristine Homsi Jorge

2009-01-01

OBJECTIVE: To analyze the results obtained in the evaluation of intra-vaginal pressure using three different brands of perineometers in nulliparous volunteers. MATERIALS AND METHODS: Twenty nulliparous women with no anatomical alterations and/or dysfunction of the pelvic floor were enrolled in our study. All the women had the ability to voluntarily contract their PFM (Pelvic Floor Muscles), as assessed by digital palpation. The intra-vaginal pressure was assessed using three different brands of perineometer (Neurodyn Evolution™, SensuPower™ and Peritron™). Each volunteer was evaluated on three alternate days by a single examiner using a single brand of perineometer on each day. In the assessment, the volunteers were required to pull (contract) their PFM in and up as strongly as possible 3 times and to sustain the contraction for 5 seconds, with an interval of 30 seconds between each pull. For the statistical analysis, a concordance correlation coefficient was used to compare the values that were obtained with each brand of perineometer. RESULTS: A moderate concordance (0.51) was found between the results from the Peritron™ and Neurodyn™ perineometers, a fair concordance (0.21) between the Peritron™ and SensuPower™ brands and a poor concordance (0.19) between the Neurodyn™ and SensuPower™ brands. CONCLUSION: The concordance of the measurements of the intra-vaginal pressure ranged from poor to moderate, suggesting that perineometers of different brands generate different results. PMID:19578656

Ensuring Reliable Natural Gas-Fired Generation with Fuel Contracts and Storage - DOE/NETL-2017/1816

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

Myles, Paul T.; Labarbara, Kirk A.; Logan, Cecilia Elise

This report finds that natural gas-fired power plants purchase fuel both on the spot market and through firm supply contracts; there do not appear to be clear drivers propelling power plants toward one or the other type. Most natural gas-fired power generators are located near major natural gas transmission pipelines, and most natural gas contracts are currently procured on the spot market. Although there is some regional variation in the type of contract used, a strong regional pattern does not emerge. Whether gas prices are higher with spot or firm contracts varies by both region and year. Natural gas pricesmore » that push the generators higher in the supply curve would make them less likely to dispatch. Most of the natural gas generators discussed in this report would be unlikely to enter firm contracts if the agreed price would decrease their dispatch frequency. The price points at which these generators would be unlikely to enter a firm contract depends upon the region that the generator is in, and how dependent that region is on natural gas. The Electric Reliability Council of Texas (ERCOT) is more dependent on natural gas than either Eastern Interconnection or Western Interconnection. This report shows that above-ground storage is prohibitively expensive with respect to providing storage for an extended operational fuel reserve comparable to the amount of on-site fuel storage used for coal-fired plants. Further, both pressurized and atmospheric tanks require a significant amount of land for storage, even to support one day’s operation at full output. Underground storage offers the only viable option for 30-day operational storage of natural gas, and that is limited by the location of suitable geologic formations and depleted fields.« less

75 FR 66402 - Self-Regulatory Organizations; Chicago Board Options Exchange, Incorporated; Notice of Filing and...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-28

... necessary systems capacity to handle the additional traffic associated with the expanded range of strike... Effectiveness of Proposed Rule Change To Expand the Range of Strike Price Intervals for VIX Options October 21... amend Rule 24.9.01(e), Terms of Index Option Contracts, to expand the range of strike price intervals...

Analyzing Contingency Contracting Purchases for Operation Iraqi Freedom (Unrestricted Version)

DTIC Science & Technology

2008-01-01

that could inform such strategic purchasing decisions. 14 We used the unique contract identification number to check for cross -organization...beds, mattresses, dressers , footlockers) Other (stools, rugs, seats, cabinets, tables, folding chairs, paintings) Generators Various power generators

Static Verification for Code Contracts

NASA Astrophysics Data System (ADS)

Fähndrich, Manuel

The Code Contracts project [3] at Microsoft Research enables programmers on the .NET platform to author specifications in existing languages such as C# and VisualBasic. To take advantage of these specifications, we provide tools for documentation generation, runtime contract checking, and static contract verification.

Contributions of Central Command and Muscle Feedback to Sympathetic Nerve Activity in Contracting Human Skeletal Muscle.

PubMed

Boulton, Daniel; Taylor, Chloe E; Macefield, Vaughan G; Green, Simon

2016-01-01

During voluntary contractions, muscle sympathetic nerve activity (MSNA) to contracting muscles increases in proportion to force but the underlying mechanisms are not clear. To shed light on these mechanisms, particularly the influences of central command and muscle afferent feedback, the present study tested the hypothesis that MSNA is greater during voluntary compared with electrically-evoked contractions. Seven male subjects performed a series of 1-min isometric dorsiflexion contractions (left leg) separated by 2-min rest periods, alternating between voluntary and electrically-evoked contractions at similar forces (5-10% of maximum). MSNA was recorded continuously (microneurography) from the left peroneal nerve and quantified from cardiac-synchronized, negative-going spikes in the neurogram. Compared with pre-contraction values, MSNA increased by 51 ± 34% (P < 0.01) during voluntary contractions but did not change significantly during electrically-evoked contractions (-8 ± 12%, P > 0.05). MSNA analyzed at 15-s intervals revealed that this effect of voluntary contraction appeared 15-30 s after contraction onset (P < 0.01), remained elevated until the end of contraction, and disappeared within 15 s after contraction. These findings suggest that central command, and not feedback from contracting muscle, is the primary mechanism responsible for the increase in MSNA to contracting muscle. The time-course of MSNA suggests that there is a longer delay in the onset of this effect compared with its cessation after contraction.

Stirling Convertor Technologies Being Developed for a Stirling Radioisotope Generator

NASA Technical Reports Server (NTRS)

Thieme, Lanny G.

2003-01-01

The Department of Energy, Lockheed Martin, Stirling Technology Company (STC), and the NASA Glenn Research Center are developing a high-efficiency Stirling Radioisotope Generator (SRG) for NASA space science missions. The SRG is being developed for multimission use, including providing electric power for unmanned Mars rovers and deep space missions. On Mars, rovers with SRGs would be used for missions that might not be able to use photovoltaic power systems, such as exploration at high Martian latitudes and missions of long duration. The projected SRG system efficiency of 23 percent will reduce the required amount of radioisotope by a factor of 4 or more in comparison to currently used Radioisotope Thermoelectric Generators. The Department of Energy recently named Lockheed Martin as the system integration contractor. Lockheed Martin has begun to develop the SRG engineering unit under contract to the Department of Energy, and has contract options to develop the qualification unit and the first flight units. The developers expect the SRG to produce about 114 Wdc at the beginning of mission, using two opposed Stirling convertors and two General Purpose Heat Source modules. STC previously developed the Stirling convertor under contract to the Department of Energy and is now providing further development as a subcontractor to Lockheed Martin. Glenn is conducting an in-house technology project to assist in developing the convertor for space qualification and mission implementation. A key milestone was recently reached with the accumulation of 12 000 hr of long-term aging on two types of neodymium-iron boron permanent magnets. These tests are characterizing any possible aging in the strength or demagnetization resistance of the magnets used in the linear alternator. Preparations are underway for a thermal/vacuum system demonstration and unattended operation during endurance testing of the 55-We Technology Demonstration Convertors. In addition, Glenn is developing a charging system for the convertors to ensure clean fills of the helium working fluid and to monitor levels of any possible contaminants at different test intervals. Possible oxidation effects depend on the level of any oxygen contamination-regenerator materials and displacer radiation shields are now being evaluated for possible oxidation effects.

Standby power generation under utility curtailment contract agreements

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

Nolan, G.J.; Puccio, V.J.; Calhoun, C.W.

1995-12-31

Many utilities in the US offer large industrial and commercial customers power sales contracts which have attractive rates under a curtailment requirement. This curtailment requirement allows the utility to require the customer to reduce its power demand to a predetermined level within a specific time period. If the required curtailment is not achieved by the customer within the allocated time period, stiff financial penalties are usually enforced by the utility. The attractiveness of the contract rates usually is proportional to the amount of curtailment required. To take advantage of these attractive rates, a customer must be able to withstand themore » curtailment without supplemental generation or must add standby generation to meet its needs. Obviously, the cost of the curtailments to the customer should not exceed the economic benefits of reduced rates. This paper reviews the alternatives faced by a curtailment contract customer together with potential load shedding and standby generation system designs. An example of implementing a curtailment contract at an existing industrial facility is presented. The example facility, Boeing Helicopters of Philadelphia, Pennsylvania required both load shedding and standby generation. The load shedding scheme is fairly complex and is controlled by a programmable logic controller (PLC). The standby generation and load shedding systems for the example facility are examined in detail. Also, lessons learned from implementing the required modifications to the example facility are discussed.« less

Army Contract Writing System (ACWS)

DTIC Science & Technology

2016-03-01

2016 Major Automated Information System Annual Report Army Contract Writing System (ACWS) Defense Acquisition Management Information Retrieval...Program Information Program Name Army Contract Writing System (ACWS) DoD Component Army Responsible Office Program Manager References MAIS...UNCLASSIFIED 4 Program Description The Army Contract Writing System (ACWS) will be the Army’s single, next-generation, enterprise-wide contract writing

Muscular control of a learned movement: the speed control system hypothesis.

PubMed

Enoka, R M

1983-01-01

The "speed control system" hypothesis, which represents an attempt to identify an invariant characteristic of learned movements, postulates that movements of variable extent are controlled by regulating the intensity of muscle contractions such that the contraction duration remains constant. The contingency set originally utilized to develop this hypothesis was expanded by examining a movement that was multidirectional and multiarticular, and executed by large muscle groups generating near maximum torques. The investigation focused on the techniques utilized by weightlifters to control lower extremity displacement during the initial phase of the double knee bend execution of the "clean" in Olympic weightlifting. The combination of the quantified muscle activity and the angular velocity, both about the knee joint, revealed a sequence of shortening-lengthening muscle contractions throughout the movement. The first two periods of net muscular activity, one extensor and the other flexor, were utilized to examine the movement for invariant characteristics. As predicted by the speed control system hypothesis, the duration of the first period of net muscle torque activity (extensor) did not vary significantly, for either group of subjects, over the relative loads examined. The duration of the second period of activity (resultant flexor muscle torque), however, was not constant across loads, and further, the direction of the change depended upon the level of expertise. The more capable lifters tended to increase the duration of the resultant flexor involvement while the less skilled athletes utilized the reverse strategy when the load was increased. Conversely, the intensity of the muscle activity for both groups of subjects and both the extensor and flexor periods covaried with load, as predicted by the hypothesis. The speed control system hypothesis, therefore, provided an appropriate explanation for the first component of the movement, the period of extensor dominated (shortening contraction) muscle torque, but was inappropriate for the subsequent interval, a resultant flexor (largely lengthening contraction) muscle torque.

[Evaluation of the principles of distribution of electrocardiographic R-R intervals for elaboration of methods of automated diagnosis of cardiac rhythm disorders].

PubMed

Tsukerman, B M; Finkel'shteĭn, I E

1987-07-01

A statistical analysis of prolonged ECG records has been carried out in patients with various heart rhythm and conductivity disorders. The distribution of absolute R-R duration values and relationships between adjacent intervals have been examined. A two-step algorithm has been constructed that excludes anomalous and "suspicious" intervals from a sample of consecutively recorded R-R intervals, until only the intervals between contractions of veritably sinus origin remain in the sample. The algorithm has been developed into a programme for microcomputer Electronica NC-80. It operates reliably even in cases of complex combined rhythm and conductivity disorders.

Mutsβ generates both expansions and contractions in a mouse model of the Fragile X-associated disorders

PubMed Central

Zhao, Xiao-Nan; Kumari, Daman; Gupta, Shikha; Wu, Di; Evanitsky, Maya; Yang, Wei; Usdin, Karen

2015-01-01

Fragile X-associated disorders are Repeat Expansion Diseases that result from expansion of a CGG/CCG-repeat in the FMR1 gene. Contractions of the repeat tract also occur, albeit at lower frequency. However, these contractions can potentially modulate disease symptoms or generate an allele with repeat numbers in the normal range. Little is known about the expansion mechanism and even less about contractions. We have previously demonstrated that the mismatch repair (MMR) protein MSH2 is required for expansions in a mouse model of these disorders. Here, we show that MSH3, the MSH2-binding partner in the MutSβ complex, is required for 98% of germ line expansions and all somatic expansions in this model. In addition, we provide evidence for two different contraction mechanisms that operate in the mouse model, a MutSβ-independent one that generates small contractions and a MutSβ-dependent one that generates larger ones. We also show that MutSβ complexes formed with the repeats have altered kinetics of ATP hydrolysis relative to complexes with bona fide MMR substrates and that MutSβ increases the stability of the CCG-hairpins at physiological temperatures. These data may have important implications for our understanding of the mechanism(s) of repeat instability and for the role of MMR proteins in this process. PMID:26420841

Effect of neuromuscular electrical stimulation on motor cortex excitability upon release of tonic muscle contraction.

PubMed

Sugawara, Kenichi; Tanabe, Shigeo; Suzuki, Tomotaka; Higashi, Toshio

The aim of the present study was to investigate the neurophysiological triggers underlying muscle relaxation from the contracted state, and to examine the mechanisms involved in this process and their subsequent modification by neuromuscular electrical stimulation (NMES). Single-pulse transcranial magnetic stimulation (TMS) was used to produce motor-evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) in 23 healthy participants, wherein motor cortex excitability was examined at the onset of voluntary muscle relaxation following a period of voluntary tonic muscle contraction. In addition, the effects of afferent input on motor cortex excitability, as produced by NMES during muscle contraction, were examined. In particular, two NMES intensities were used for analysis: 1.2 times the sensory threshold and 1.2 times the motor threshold (MT). Participants were directed to execute constant wrist extensions and to release muscle contraction in response to an auditory "GO" signal. MEPs were recorded from the flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles, and TMS was applied at three different time intervals (30, 60, and 90 ms) after the "GO" signal. Motor cortex excitability was greater during voluntary ECR and FCR relaxation using high-intensity NMES, and relaxation time was decreased. Each parameter differed significantly between 30 and 60 ms. Moreover, in both muscles, SICI was larger in the presence than in the absence of NMES. Therefore, the present findings suggest that terminating a muscle contraction triggers transient neurophysiological mechanisms that facilitate the NMES-induced modulation of cortical motor excitability in the period prior to muscle relaxation. High-intensity NMES might facilitate motor cortical excitability as a function of increased inhibitory intracortical activity, and therefore serve as a transient trigger for the relaxation of prime mover muscles in a therapeutic context.

Premature Ventricular Contraction Coupling Interval Variability Destabilizes Cardiac Neuronal and Electrophysiological Control: Insights From Simultaneous Cardioneural Mapping.

PubMed

Hamon, David; Rajendran, Pradeep S; Chui, Ray W; Ajijola, Olujimi A; Irie, Tadanobu; Talebi, Ramin; Salavatian, Siamak; Vaseghi, Marmar; Bradfield, Jason S; Armour, J Andrew; Ardell, Jeffrey L; Shivkumar, Kalyanam

2017-04-01

Variability in premature ventricular contraction (PVC) coupling interval (CI) increases the risk of cardiomyopathy and sudden death. The autonomic nervous system regulates cardiac electrical and mechanical indices, and its dysregulation plays an important role in cardiac disease pathogenesis. The impact of PVCs on the intrinsic cardiac nervous system, a neural network on the heart, remains unknown. The objective was to determine the effect of PVCs and CI on intrinsic cardiac nervous system function in generating cardiac neuronal and electric instability using a novel cardioneural mapping approach. In a porcine model (n=8), neuronal activity was recorded from a ventricular ganglion using a microelectrode array, and cardiac electrophysiological mapping was performed. Neurons were functionally classified based on their response to afferent and efferent cardiovascular stimuli, with neurons that responded to both defined as convergent (local reflex processors). Dynamic changes in neuronal activity were then evaluated in response to right ventricular outflow tract PVCs with fixed short, fixed long, and variable CI. PVC delivery elicited a greater neuronal response than all other stimuli ( P <0.001). Compared with fixed short and long CI, PVCs with variable CI had a greater impact on neuronal response ( P <0.05 versus short CI), particularly on convergent neurons ( P <0.05), as well as neurons receiving sympathetic ( P <0.05) and parasympathetic input ( P <0.05). The greatest cardiac electric instability was also observed after variable (short) CI PVCs. Variable CI PVCs affect critical populations of intrinsic cardiac nervous system neurons and alter cardiac repolarization. These changes may be critical for arrhythmogenesis and remodeling, leading to cardiomyopathy. © 2017 American Heart Association, Inc.

Independent Prognostic Value of Stroke Volume Index in Patients With Immunoglobulin Light Chain Amyloidosis.

PubMed

2018-05-01

Heart involvement is the most important prognostic determinant in AL amyloidosis patients. Echocardiography is a cornerstone for the diagnosis and provides important prognostic information. We studied 754 patients with AL amyloidosis who underwent echocardiographic assessment at the Mayo Clinic, including a Doppler-derived measurement of stroke volume (SV) within 30 days of their diagnosis to explore the prognostic role of echocardiographic variables in the context of a well-established soluble cardiac biomarker staging system. Reproducibility of SV, myocardial contraction fraction, and left ventricular strain was assessed in a separate, yet comparable, study cohort of 150 patients from the Pavia Amyloidosis Center. The echocardiographic measures most predictive for overall survival were SV index <33 mL/min, myocardial contraction fraction <34%, and cardiac index <2.4 L/min/m 2 with respective hazard ratios (95% confidence intervals) of 2.95 (2.37-3.66), 2.36 (1.96-2.85), and 2.32 (1.91-2.80). For the subset that had left ventricular strain performed, the prognostic cut point was -14% (hazard ratios, 2.70; 95% confidence intervals, 1.84-3.96). Each parameter was independent of systolic blood pressure, Mayo staging system (NT-proBNP [N-terminal pro-B-type natriuretic peptide] and troponin), and ejection fraction on multivariable analysis. Simple predictive models for survival, including biomarker staging along with SV index or left ventricular strain, were generated. SV index prognostic performance was similar to left ventricular strain in predicting survival in AL amyloidosis, independently of biomarker staging. Because SV index is routinely calculated and widely available, it could serve as the preferred echocardiographic measure to predict outcomes in AL amyloidosis patients. © 2018 American Heart Association, Inc.

Premature Ventricular Contraction Coupling Interval Variability Destabilizes Cardiac Neuronal and Electrophysiological Control: Insights from Simultaneous Cardio-Neural Mapping

PubMed Central

Hamon, David; Rajendran, Pradeep S.; Chui, Ray W.; Ajijola, Olujimi A.; Irie, Tadanobu; Talebi, Ramin; Salavatian, Siamak; Vaseghi, Marmar; Bradfield, Jason S.; Armour, J. Andrew; Ardell, Jeffrey L.; Shivkumar, Kalyanam

2017-01-01

Background Variability in premature ventricular contraction (PVC) coupling interval (CI) increases the risk of cardiomyopathy and sudden death. The autonomic nervous system regulates cardiac electrical and mechanical indices, and its dysregulation plays an important role in cardiac disease pathogenesis. The impact of PVCs on the intrinsic cardiac nervous system (ICNS), a neural network on the heart, remains unknown. The objective was to determine the effect of PVCs and CI on ICNS function in generating cardiac neuronal and electrical instability using a novel cardio-neural mapping approach. Methods and Results In a porcine model (n=8) neuronal activity was recorded from a ventricular ganglion using a microelectrode array, and cardiac electrophysiological mapping was performed. Neurons were functionally classified based on their response to afferent and efferent cardiovascular stimuli, with neurons that responded to both defined as convergent (local reflex processors). Dynamic changes in neuronal activity were then evaluated in response to right ventricular outflow tract PVCs with fixed short, fixed long, and variable CI. PVC delivery elicited a greater neuronal response than all other stimuli (P<0.001). Compared to fixed short and long CI, PVCs with variable CI had a greater impact on neuronal response (P<0.05 versus short CI), particularly on convergent neurons (P<0.05), as well as neurons receiving sympathetic (P<0.05) and parasympathetic input (P<0.05). The greatest cardiac electrical instability was also observed following variable (short) CI PVCs. Conclusions Variable CI PVCs affect critical populations of ICNS neurons and alter cardiac repolarization. These changes may be critical for arrhythmogenesis and remodeling leading to cardiomyopathy. PMID:28408652

Generation Of A Mouse Model For Schwannomatosis

DTIC Science & Technology

2010-09-01

TITLE: Generation of a Mouse Model for Schwannomatosis PRINCIPAL INVESTIGATOR: Long-Sheng Chang, Ph.D. CONTRACTING ORGANIZATION: The...Annual 3. DATES COVERED (From - To) 1 Sep 2009 - 31 Aug 2010 4. TITLE AND SUBTITLE Generation of a Mouse Model for Schwannomatosis 5a. CONTRACT...hypothesis involving inactivation of both the INI1/SNF5 and NF2 tumor suppressor genes in the formation of schwannomatosis -associated tumors. To

Eccentric Contraction-Induced Muscle Injury: Reproducible, Quantitative, Physiological Models to Impair Skeletal Muscle’s Capacity to Generate Force

PubMed Central

Call, Jarrod A.; Lowe, Dawn A.

2018-01-01

In order to investigate the molecular and cellular mechanisms of muscle regeneration an experimental injury model is required. Advantages of eccentric contraction-induced injury are that it is a controllable, reproducible, and physiologically relevant model to cause muscle injury, with injury being defined as a loss of force generating capacity. While eccentric contractions can be incorporated into conscious animal study designs such as downhill treadmill running, electrophysiological approaches to elicit eccentric contractions and examine muscle contractility, for example before and after the injurious eccentric contractions, allows researchers to circumvent common issues in determining muscle function in a conscious animal (e.g., unwillingness to participate). Herein, we describe in vitro and in vivo methods that are reliable, repeatable, and truly maximal because the muscle contractions are evoked in a controlled, quantifiable manner independent of subject motivation. Both methods can be used to initiate eccentric contraction-induced injury and are suitable for monitoring functional muscle regeneration hours to days to weeks post-injury. PMID:27492161

Coiled fiber scaffolds embedded with gold nanoparticles improve the performance of engineered cardiac tissues

NASA Astrophysics Data System (ADS)

Fleischer, Sharon; Shevach, Michal; Feiner, Ron; Dvir, Tal

2014-07-01

Coiled perimysial fibers within the heart muscle provide it with the ability to contract and relax efficiently. Here, we report on a new nanocomposite scaffold for cardiac tissue engineering, integrating coiled electrospun fibers with gold nanoparticles. Cultivation of cardiac cells within the hybrid scaffolds promoted cell organization into elongated and aligned tissues generating a strong contraction force, high contraction rate and low excitation threshold.Coiled perimysial fibers within the heart muscle provide it with the ability to contract and relax efficiently. Here, we report on a new nanocomposite scaffold for cardiac tissue engineering, integrating coiled electrospun fibers with gold nanoparticles. Cultivation of cardiac cells within the hybrid scaffolds promoted cell organization into elongated and aligned tissues generating a strong contraction force, high contraction rate and low excitation threshold. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00300d

Constant-load versus heart rate-targeted exercise - Responses of systolic intervals

NASA Technical Reports Server (NTRS)

Lance, V. Q.; Spodick, D. H.

1975-01-01

Various systolic intervals were measured prior to and during heart rate-targeted bicycle ergometer exercise. There were striking similarities within each matched exercise set for Q-Im, isovolumetric contraction time, preejection period (PEP), and PEP/left ventricular ejection time (LVET). LVET was significantly shorter for rate-targeted exercise. It is concluded that either constant-load or rate-targeted bicycle ergometry may be used with the choice of method determined by the purpose of the protocol, and that systolic intervals (except LVET) should not be much altered owing to the method chosen.

A meta-analysis of single-case research on behavior contracts: effects on behavioral and academic outcomes among children and youth.

PubMed

Bowman-Perrott, Lisa; Burke, Mack D; de Marin, Sharon; Zhang, Nan; Davis, Heather

2015-03-01

The purpose of this meta-analysis was to quantitatively summarize the single-case research (SCR) literature on the use of behavior contracts with children and youth. This study examined the efficacy of behavior contracts on problem behaviors and academic behaviors across 18 SCR studies. Academic and behavioral outcomes were examined for 58 children and youth ages 5 to 21 using the TauU effect size index. Results indicated the overall moderate effect of the use of behavior contracts was ES = .57 (95% confidence interval [CI95] = [0.55, 0.58]) with a range of effects across studies (ES = .27 to ES = 1.00). Moderator analyses indicated that behavior contracts are beneficial for students regardless of grade level, gender, or disability status. Findings suggest that the intervention is more effective in reducing inappropriate behaviors than increasing appropriate behaviors, and that academic outcomes are positively affected by behavior contracting. © The Author(s) 2014.

Long Wavelength Electromagnetic Light Bullets Generated by a 10.6 micron CO2 Ultrashort Pulsed Source

DTIC Science & Technology

2016-11-29

AFRL-AFOSR-VA-TR-2016-0365 Long Wavelength Electromagnetic Light Bullets Generated by a 10.6 micron CO2 Ultrashort Pulsed Source Jerome Moloney...SUBTITLE "Long Wavelength Electromagnetic Light Bullets Generated by a 10.6 micron CO2 Ultrashort Pulsed Source 5a. CONTRACT NUMBER FA9550-15-1-0272 5b...afosr.reports.sgizmo.com/s3/> Subject: Final Report to Dr. Arje Nachman Contract/Grant Title: Long Wavelength Electromagnetic Light Bullets Generated by a 10.6

Generation of Breast Cancer Stem Cells by the EMT

DTIC Science & Technology

2009-10-01

shift in the type of human breast cancer cells. We began to use experimentally immortalized HMLE cells that were then transformed through...Generation of Breast Cancer Stem Cells by the EMT PRINCIPAL INVESTIGATOR: Robert A. Weinberg, Ph.D. CONTRACTING...Generation of Breast Cancer Stem Cells by the EMT 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-08-1-0464 5c. PROGRAM ELEMENT NUMBER 6

Optimizing Tensor Contraction Expressions for Hybrid CPU-GPU Execution

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

Ma, Wenjing; Krishnamoorthy, Sriram; Villa, Oreste

2013-03-01

Tensor contractions are generalized multidimensional matrix multiplication operations that widely occur in quantum chemistry. Efficient execution of tensor contractions on Graphics Processing Units (GPUs) requires several challenges to be addressed, including index permutation and small dimension-sizes reducing thread block utilization. Moreover, to apply the same optimizations to various expressions, we need a code generation tool. In this paper, we present our approach to automatically generate CUDA code to execute tensor contractions on GPUs, including management of data movement between CPU and GPU. To evaluate our tool, GPU-enabled code is generated for the most expensive contractions in CCSD(T), a key coupledmore » cluster method, and incorporated into NWChem, a popular computational chemistry suite. For this method, we demonstrate speedup over a factor of 8.4 using one GPU (instead of one core per node) and over 2.6 when utilizing the entire system using hybrid CPU+GPU solution with 2 GPUs and 5 cores (instead of 7 cores per node). Finally, we analyze the implementation behavior on future GPU systems.« less

Multimodal second harmonic generation and two photon fluorescence imaging of microdomain calcium contraction coupling in single cardiomyocytes

NASA Astrophysics Data System (ADS)

Chan, James; Awasthi, Samir; Izu, Leighton; Mao, Ziliang; Jian, Zhong; Landas, Trevor; Lerner, Aaron; Shimkunas, Rafael; Woldeyesus, Rahwa; Bossuyt, Julie; Wood, Brittani; Chen, Yi-Je; Matthews, Dennis; Lieu, Deborah; Chiamvimonvat, Nipavan; Lam, Kit; Chen-Izu, Ye

2016-11-01

The objective of this study was to develop a method for simultaneously measuring the calcium and contraction dynamics of single, live cardiomyocytes at high spatial resolutions. Such measurements are important to investigate local calcium release and the mechanical response at the sarcomere level (i.e. the basic unit of contraction), which have important implications in cardiac dysfunction and arrhythmias in conditions such as hypertension, atrial fibrillation, and myocardial infarction. Here, we describe a multimodal second harmonic generation (SHG) and two photon fluorescence (2PF) microscopy technique that is used to simultaneously measure subsarcomere calcium and contraction events at high spatial and temporal resolutions. The method takes advantage of the label-free nature of SHG for imaging the sarcomeres and the high spatial colocalization of the SHG signal and the fluorescence signal excited from calcium indicators. This microscope was used to measure calcium sparks and waves and associated contractions in subcellular microdomains, leading to the generation of subcellular strain. We anticipate this new imaging tool will play an important role in studying mechanical stress-induced heart disease.

An Experimental Model Using Cultured Cardiac Myocytes for a Study of the Generation of Premature Ventricular Contractions Under Ultrasound Exposure

NASA Astrophysics Data System (ADS)

Kudo, Nobuki; Yamamoto, Masaya

2011-09-01

It is known that use of a contrast agents in echocardiography increases the probability of generation of premature ventricular contractions (PVCs). As a basic study to elucidate the mechanisms and to reduce adverse effects, the generation of PVCs was investigated using cultured cardiac myocytes instead of the intact heart in vivo. Cardiac myocytes were isolated from neonatal rats and cultured on a cover slip. The myocyte sample was exposed to pulsed ultrasound with microbubbles adjacent to the myocytes, and generation of PVCs was examined with ultrasound exposure at various delay times after onset of myocyte contraction. The experimental results showed that generation of PVCs had a stable threshold delay time and that PVCs were generated only when myocytes were exposed to ultrasound with delay times longer than the threshold. The results indicate that the model used in this study is useful for revealing the mechanisms by which PVCs are induced by ultrasound exposure.

History dependence of human muscle-fiber conduction velocity during voluntary isometric contractions.

PubMed

McGill, Kevin C; Lateva, Zoia C

2011-09-01

The conduction velocity (CV) of a muscle fiber is affected by the fiber's discharge history going back ∼1 s. We investigated this dependence by measuring CV fluctuations during voluntary isometric contractions of the human brachioradialis muscle. We recorded electromyogram (EMG) signals simultaneously from multiple intramuscular electrodes, identified potentials belonging to the same motor unit using EMG decomposition, and estimated the CV of each discharge from the interpotential interval. In 12 of 14 subjects, CV increased by ∼10% during the first second after recruitment and then fluctuated by about ±2% in a way that mirrored the fluctuations in the instantaneous firing rate. The CV profile could be precisely described in terms of the discharge history by a simple mathematical model. In the other two subjects, and one subject retested after cooling the arm, the CV fluctuations were inversely correlated with instantaneous firing rate. In all subjects, CV was additionally affected by very short interdischarge intervals (<25 ms): it was increased in doublets at recruitment, but decreased in doublets during continuous firing and after short interdischarge intervals in doubly innervated fibers. CV also exhibited a slow trend of about -0.05%/s that did not depend on the immediate discharge history. We suggest that measurements of CV fluctuations during voluntary contractions, or during stimulation protocols that involve longer and more complex stimulation patterns than are currently being used, may provide a sensitive approach for estimating the dynamic characteristics of ion channels in the human muscle-fiber membrane.

History dependence of human muscle-fiber conduction velocity during voluntary isometric contractions

PubMed Central

Lateva, Zoia C.

2011-01-01

The conduction velocity (CV) of a muscle fiber is affected by the fiber's discharge history going back ∼1 s. We investigated this dependence by measuring CV fluctuations during voluntary isometric contractions of the human brachioradialis muscle. We recorded electromyogram (EMG) signals simultaneously from multiple intramuscular electrodes, identified potentials belonging to the same motor unit using EMG decomposition, and estimated the CV of each discharge from the interpotential interval. In 12 of 14 subjects, CV increased by ∼10% during the first second after recruitment and then fluctuated by about ±2% in a way that mirrored the fluctuations in the instantaneous firing rate. The CV profile could be precisely described in terms of the discharge history by a simple mathematical model. In the other two subjects, and one subject retested after cooling the arm, the CV fluctuations were inversely correlated with instantaneous firing rate. In all subjects, CV was additionally affected by very short interdischarge intervals (<25 ms): it was increased in doublets at recruitment, but decreased in doublets during continuous firing and after short interdischarge intervals in doubly innervated fibers. CV also exhibited a slow trend of about −0.05%/s that did not depend on the immediate discharge history. We suggest that measurements of CV fluctuations during voluntary contractions, or during stimulation protocols that involve longer and more complex stimulation patterns than are currently being used, may provide a sensitive approach for estimating the dynamic characteristics of ion channels in the human muscle-fiber membrane. PMID:21565985

Contracting for Agile Software Development in the Department of Defense: An Introduction

DTIC Science & Technology

2015-08-01

Requirements are fixed at a more granular level; reviews of the work product happen more frequently and assess each individual increment rather than a “ big bang ...boundaries than “ big - bang ” development. The implementation of incremental or progressive reviews enables just that—any issues identified at the time of the...the contract needs to support the delivery of deployable software at defined increments/intervals, rather than incentivizing “ big - bang ” efforts or

Cross-cultural estimation of the human generation interval for use in genetics-based population divergence studies.

PubMed

Fenner, Jack N

2005-10-01

The length of the human generation interval is a key parameter when using genetics to date population divergence events. However, no consensus exists regarding the generation interval length, and a wide variety of interval lengths have been used in recent studies. This makes comparison between studies difficult, and questions the accuracy of divergence date estimations. Recent genealogy-based research suggests that the male generation interval is substantially longer than the female interval, and that both are greater than the values commonly used in genetics studies. This study evaluates each of these hypotheses in a broader cross-cultural context, using data from both nation states and recent hunter-gatherer societies. Both hypotheses are supported by this study; therefore, revised estimates of male, female, and overall human generation interval lengths are proposed. The nearly universal, cross-cultural nature of the evidence justifies using these proposed estimates in Y-chromosomal, mitochondrial, and autosomal DNA-based population divergence studies.

Identification of a rhythmic firing pattern in the enteric nervous system that generates rhythmic electrical activity in smooth muscle.

PubMed

Spencer, Nick J; Hibberd, Timothy J; Travis, Lee; Wiklendt, Lukasz; Costa, Marcello; Hu, Hongzhen; Brookes, Simon J; Wattchow, David A; Dinning, Phil G; Keating, Damien J; Sorensen, Julian

2018-05-28

The enteric nervous system (ENS) contains millions of neurons essential for organization of motor behaviour of the intestine. It is well established the large intestine requires ENS activity to drive propulsive motor behaviours. However, the firing pattern of the ENS underlying propagating neurogenic contractions of the large intestine remains unknown. To identify this, we used high resolution neuronal imaging with electrophysiology from neighbouring smooth muscle. Myoelectric activity underlying propagating neurogenic contractions along murine large intestine (referred to as colonic migrating motor complexes, CMMCs) consisted of prolonged bursts of rhythmic depolarizations at a frequency of ∼2 Hz. Temporal coordination of this activity in the smooth muscle over large spatial fields (∼7mm, longitudinally) was dependent on the ENS. During quiescent periods between neurogenic contractions, recordings from large populations of enteric neurons, in mice of either sex, revealed ongoing activity. The onset of neurogenic contractions was characterized by the emergence of temporally synchronized activity across large populations of excitatory and inhibitory neurons. This neuronal firing pattern was rhythmic and temporally synchronized across large numbers of ganglia at ∼2 Hz. ENS activation preceded smooth muscle depolarization, indicating rhythmic depolarizations in smooth muscle were controlled by firing of enteric neurons. The cyclical emergence of temporally coordinated firing of large populations of enteric neurons represents a unique neural motor pattern outside the central nervous system. This is the first direct observation of rhythmic firing in the ENS underlying rhythmic electrical depolarizations in smooth muscle. The pattern of neuronal activity we identified underlies the generation of CMMCs. SIGNIFICANCE STATEMENT How the enteric nervous system (ENS) generates neurogenic contractions of smooth muscle in the gastrointestinal (GI) tract has been a long-standing mystery in vertebrates. It is well known that myogenic pacemaker cells exist in the GI-tract (called Interstitial cells of Cajal, ICC) that generate rhythmic myogenic contractions. However, the mechanisms underlying the generation of rhythmic neurogenic contractions of smooth muscle in the GI-tract remains unknown. We developed a high resolution neuronal imaging method with electrophysiology to address this issue. This technique revealed a novel pattern of rhythmic coordinated neuronal firing in the ENS that has never been identified. Rhythmic neuronal firing in the ENS was found to generate rhythmic neurogenic depolarizations in smooth muscle that underlie contraction of the GI-tract. Copyright © 2018 the authors.

[Heart rate variability study based on a novel RdR RR Intervals Scatter Plot].

PubMed

Lu, Hongwei; Lu, Xiuyun; Wang, Chunfang; Hua, Youyuan; Tian, Jiajia; Liu, Shihai

2014-08-01

On the basis of Poincare scatter plot and first order difference scatter plot, a novel heart rate variability (HRV) analysis method based on scatter plots of RR intervals and first order difference of RR intervals (namely, RdR) was proposed. The abscissa of the RdR scatter plot, the x-axis, is RR intervals and the ordinate, y-axis, is the difference between successive RR intervals. The RdR scatter plot includes the information of RR intervals and the difference between successive RR intervals, which captures more HRV information. By RdR scatter plot analysis of some records of MIT-BIH arrhythmias database, we found that the scatter plot of uncoupled premature ventricular contraction (PVC), coupled ventricular bigeminy and ventricular trigeminy PVC had specific graphic characteristics. The RdR scatter plot method has higher detecting performance than the Poincare scatter plot method, and simpler and more intuitive than the first order difference method.

Fluctuations in isometric muscle force can be described by one linear projection of low-frequency components of motor unit discharge rates

PubMed Central

Negro, Francesco; Holobar, Aleš; Farina, Dario

2009-01-01

The aim of the study was to investigate the relation between linear transformations of motor unit discharge rates and muscle force. Intramuscular (wire electrodes) and high-density surface EMG (13 × 5 electrode grid) were recorded from the abductor digiti minimi muscle of eight healthy men during 60 s contractions at 5%, 7.5% and 10% of the maximal force. Spike trains of a total of 222 motor units were identified from the EMG recordings with decomposition algorithms. Principal component analysis of the smoothed motor unit discharge rates indicated that one component (first common component, FCC) described 44.2 ± 7.5% of the total variability of the smoothed discharge rates when computed over the entire contraction interval and 64.3 ± 10.2% of the variability when computed over 5 s intervals. When the FCC was computed from four or more motor units per contraction, it correlated with the force produced by the muscle (62.7 ± 10.1%) by a greater degree (P < 0.001) than the smoothed discharge rates of individual motor units (41.4 ± 7.8%). The correlation between FCC and the force signal increased up to 71.8 ± 13.1% when the duration and the shape of the smoothing window for discharge rates were similar to the average motor unit twitch force. Moreover, the coefficients of variation (CoV) for the force and for the FCC signal were correlated in all subjects (R2 range = 0.14–0.56; P < 0.05) whereas the CoV for force was correlated to the interspike interval variability in only one subject (R2= 0.12; P < 0.05). Similar results were further obtained from measures on the tibialis anterior muscle of an additional eight subjects during contractions at forces up to 20% of the maximal force (e.g. FCC explained 59.8 ± 11.0% of variability of the smoothed discharge rates). In conclusion, one signal captures most of the underlying variability of the low-frequency components of motor unit discharge rates and explains large part of the fluctuations in the motor output during isometric contractions. PMID:19840996

Fluctuations in isometric muscle force can be described by one linear projection of low-frequency components of motor unit discharge rates.

PubMed

Negro, Francesco; Holobar, Ales; Farina, Dario

2009-12-15

The aim of the study was to investigate the relation between linear transformations of motor unit discharge rates and muscle force. Intramuscular (wire electrodes) and high-density surface EMG (13 x 5 electrode grid) were recorded from the abductor digiti minimi muscle of eight healthy men during 60 s contractions at 5%, 7.5% and 10% of the maximal force. Spike trains of a total of 222 motor units were identified from the EMG recordings with decomposition algorithms. Principal component analysis of the smoothed motor unit discharge rates indicated that one component (first common component, FCC) described 44.2 +/- 7.5% of the total variability of the smoothed discharge rates when computed over the entire contraction interval and 64.3 +/- 10.2% of the variability when computed over 5 s intervals. When the FCC was computed from four or more motor units per contraction, it correlated with the force produced by the muscle (62.7 +/- 10.1%) by a greater degree (P < 0.001) than the smoothed discharge rates of individual motor units (41.4 +/- 7.8%). The correlation between FCC and the force signal increased up to 71.8 +/- 13.1% when the duration and the shape of the smoothing window for discharge rates were similar to the average motor unit twitch force. Moreover, the coefficients of variation (CoV) for the force and for the FCC signal were correlated in all subjects (R(2) range = 0.14-0.56; P < 0.05) whereas the CoV for force was correlated to the interspike interval variability in only one subject (R(2) = 0.12; P < 0.05). Similar results were further obtained from measures on the tibialis anterior muscle of an additional eight subjects during contractions at forces up to 20% of the maximal force (e.g. FCC explained 59.8 +/- 11.0% of variability of the smoothed discharge rates). In conclusion, one signal captures most of the underlying variability of the low-frequency components of motor unit discharge rates and explains large part of the fluctuations in the motor output during isometric contractions.

Kinetics and mechanics of clot contraction are governed by the molecular and cellular composition of the blood.

PubMed

Tutwiler, Valerie; Litvinov, Rustem I; Lozhkin, Andrey P; Peshkova, Alina D; Lebedeva, Tatiana; Ataullakhanov, Fazoil I; Spiller, Kara L; Cines, Douglas B; Weisel, John W

2016-01-07

Platelet-driven blood clot contraction (retraction) is thought to promote wound closure and secure hemostasis while preventing vascular occlusion. Notwithstanding its importance, clot contraction remains a poorly understood process, partially because of the lack of methodology to quantify its dynamics and requirements. We used a novel automated optical analyzer to continuously track in vitro changes in the size of contracting clots in whole blood and in variously reconstituted samples. Kinetics of contraction was complemented with dynamic rheometry to characterize the viscoelasticity of contracting clots. This combined approach enabled investigation of the coordinated mechanistic impact of platelets, including nonmuscle myosin II, red blood cells (RBCs), fibrin(ogen), factor XIIIa (FXIIIa), and thrombin on the kinetics and mechanics of the contraction process. Clot contraction is composed of 3 sequential phases, each characterized by a distinct rate constant. Thrombin, Ca(2+), the integrin αIIbβ3, myosin IIa, FXIIIa cross-linking, and platelet count all promote 1 or more phases of the clot contraction process. In contrast, RBCs impair contraction and reduce elasticity, while increasing the overall contractile stress generated by the platelet-fibrin meshwork. A better understanding of the mechanisms by which blood cells, fibrin(ogen), and platelet-fibrin interactions modulate clot contraction may generate novel approaches to reveal and to manage thrombosis and hemostatic disorders. © 2016 by The American Society of Hematology.

Kinetics and mechanics of clot contraction are governed by the molecular and cellular composition of the blood

PubMed Central

Tutwiler, Valerie; Litvinov, Rustem I.; Lozhkin, Andrey P.; Peshkova, Alina D.; Lebedeva, Tatiana; Ataullakhanov, Fazoil I.; Spiller, Kara L.; Cines, Douglas B.

2016-01-01

Platelet-driven blood clot contraction (retraction) is thought to promote wound closure and secure hemostasis while preventing vascular occlusion. Notwithstanding its importance, clot contraction remains a poorly understood process, partially because of the lack of methodology to quantify its dynamics and requirements. We used a novel automated optical analyzer to continuously track in vitro changes in the size of contracting clots in whole blood and in variously reconstituted samples. Kinetics of contraction was complemented with dynamic rheometry to characterize the viscoelasticity of contracting clots. This combined approach enabled investigation of the coordinated mechanistic impact of platelets, including nonmuscle myosin II, red blood cells (RBCs), fibrin(ogen), factor XIIIa (FXIIIa), and thrombin on the kinetics and mechanics of the contraction process. Clot contraction is composed of 3 sequential phases, each characterized by a distinct rate constant. Thrombin, Ca2+, the integrin αIIbβ3, myosin IIa, FXIIIa cross-linking, and platelet count all promote 1 or more phases of the clot contraction process. In contrast, RBCs impair contraction and reduce elasticity, while increasing the overall contractile stress generated by the platelet-fibrin meshwork. A better understanding of the mechanisms by which blood cells, fibrin(ogen), and platelet-fibrin interactions modulate clot contraction may generate novel approaches to reveal and to manage thrombosis and hemostatic disorders. PMID:26603837

Comparison of the ballistic contractile responses generated during microstimulation of single human motor axons with brief irregular and regular stimuli.

PubMed

Leitch, Michael; Macefield, Vaughan G

2017-08-01

Ballistic contractions are induced by brief, high-frequency (60-100 Hz) trains of action potentials in motor axons. During ramp voluntary contractions, human motoneurons exhibit significant discharge variability of ∼20% and have been shown to be advantageous to the neuromuscular system. We hypothesized that ballistic contractions incorporating discharge variability would generate greater isometric forces than regular trains with zero variability. High-impedance tungsten microelectrodes were inserted into human fibular nerve, and single motor axons were stimulated with both irregular and constant-frequency stimuli at mean frequencies ranging from 57.8 to 68.9 Hz. Irregular trains generated significantly greater isometric peak forces than regular trains over identical mean frequencies. The high forces generated by ballistic contractions are not based solely on high frequencies, but rather a combination of high firing rates and discharge irregularity. It appears that irregular ballistic trains take advantage of the "catchlike property" of muscle, allowing augmentation of force. Muscle Nerve 56: 292-297, 2017. © 2016 Wiley Periodicals, Inc.

VARIABLE TIME-INTERVAL GENERATOR

DOEpatents

Gross, J.E.

1959-10-31

This patent relates to a pulse generator and more particularly to a time interval generator wherein the time interval between pulses is precisely determined. The variable time generator comprises two oscillators with one having a variable frequency output and the other a fixed frequency output. A frequency divider is connected to the variable oscillator for dividing its frequency by a selected factor and a counter is used for counting the periods of the fixed oscillator occurring during a cycle of the divided frequency of the variable oscillator. This defines the period of the variable oscillator in terms of that of the fixed oscillator. A circuit is provided for selecting as a time interval a predetermined number of periods of the variable oscillator. The output of the generator consists of a first pulse produced by a trigger circuit at the start of the time interval and a second pulse marking the end of the time interval produced by the same trigger circuit.

Late Holocene paleoseismicity, tsunamis and relative sea- level changes along the south-central Cascadia subduction zone, southern Oregon, United States of America

NASA Astrophysics Data System (ADS)

Witter, Robert Carleton

1999-10-01

This dissertation investigates stratigraphic evidence for great (M w >= 8) earthquakes, tsunamis and relative sea-level change at three coastal sites above the Cascadia subduction zone (CSZ). Accelerator mass spectrometry radiocarbon analyses, diatom analyses and vibracoring techniques were employed. Euchre Creek marsh stratigraphic sequences contain four sand beds deposited by extreme storm waves within the last 600 years and a tsunami ~300 years ago. A 150- year recurrence interval for sand deposition compared to an average recurrence interval of 500-540 years for great Cascadia, earthquakes precludes local tsunamis that accompany Cascadia earthquakes as the only candidate depositional mechanism for the sand beds. Alternatively, magnitude-frequency analyses of extreme ocean levels generated during El Niño years suggest that storm- wave runup is a more likely mechanism for sand deposition in washover settings than either locally or remotely generated tsunamis. Late Holocene stratigraphic sequences at the Coquille River estuary provide a ~6600-year record of twelve great Cascadia earthquakes and attendant tsunamis in southern Oregon. A relative sea-level history chronicles repeated sudden expansion followed by gradual emergence of the Coquille estuary in response to the earthquake cycle. The average earthquake-recurrence interval for the central CSZ (~570-590 yrs) overlaps similar estimates for northern Oregon estuaries. In contrast, more inferred earthquakes recorded at Willapa and Humboldt Bays in the last ~2000 years compared to the earthquake record at Coquille suggest that segmented rupture of the CSZ occurs. Late Holocene (since 6.3 ka) relative sea-level data generated within the Coquille estuary allow 20 m of vertical deformation across the Coquille anticline in the last 80 ky. Contrasting relative sea-level histories in southern Oregon provide evidence for late Holocene contraction on upper-plate anticlines. Two relative sea-level curves, 35 km apart, show 0.5-0.6 m/ka difference in uplift rate, although both sites demonstrate long-term tectonic uplift. Upper-plate structures above the central CSZ probably deform during megathrust events. The Cape Blanco and Coquille anticlines overlie a candidate segment boundary because they separate subduction zone segments with different earthquake histories. This dissertation includes co-authored material.

Systolic and diastolic time intervals in pulsus alternans - Significance of alternating isovolumic relaxation

NASA Technical Reports Server (NTRS)

Spodick, D. H.; Quarry, V. M.; Khan, A. H.

1974-01-01

Systolic and diastolic time intervals in 14 cardiac patients with pulsus alternans revealed significant alternation of preinjection period (PEP), isovolumic contraction time (IVCT), left ventricular ejection time (LVET), ejection time index (ETI), PEP/LVET, and carotid dD/dt with better functional values in the strong beats. Cycle length, duration of electromechanical systole (EMS) and total diastole, i.e., isovolumic relaxation period (IRP) and diastolic filling period (DFP) occurred in 7 out of 8 patients. These diastolic intervals alternated reciprocally such that the IRP of the strong beats encroached upon the DFP of the next (weak) beats.

Scientific Data Analysis and Software Support: Geodynamics

NASA Technical Reports Server (NTRS)

Klosko, Steven; Sanchez, B. (Technical Monitor)

2000-01-01

The support on this contract centers on development of data analysis strategies, geodynamic models, and software codes to study four-dimensional geodynamic and oceanographic processes, as well as studies and mission support for near-Earth and interplanetary satellite missions. SRE had a subcontract to maintain the optical laboratory for the LTP, where instruments such as MOLA and GLAS are developed. NVI performed work on a Raytheon laser altimetry task through a subcontract, providing data analysis and final data production for distribution to users. HBG had a subcontract for specialized digital topography analysis and map generation. Over the course of this contract, Raytheon ITSS staff have supported over 60 individual tasks. Some tasks have remained in place during this entire interval whereas others have been completed and were of shorter duration. Over the course of events, task numbers were changed to reflect changes in the character of the work or new funding sources. The description presented below will detail the technical accomplishments that have been achieved according to their science and technology areas. What will be shown is a brief overview of the progress that has been made in each of these investigative and software development areas. Raytheon ITSS staff members have received many awards for their work on this contract, including GSFC Group Achievement Awards for TOPEX Precision Orbit Determination and the Joint Gravity Model One Team. NASA JPL gave the TOPEX/POSEIDON team a medal commemorating the completion of the primary mission and a Certificate of Appreciation. Raytheon ITSS has also received a Certificate of Appreciation from GSFC for its extensive support of the Shuttle Laser Altimeter Experiment.

Postactivation potentiation: effect of various recovery intervals on bench press power performance.

PubMed

Ferreira, Sandra Lívia de Assis; Panissa, Valéria Leme Gonçalves; Miarka, Bianca; Franchini, Emerson

2012-03-01

Postactivation potentiation (PAP) is a strategy used to improve performance in power activities. The aim of this study was to determine if power during bench press exercise was increased when preceded by 1 repetition maximum (1RM) in the same exercise and to determine which time interval could optimize PAP response. For this, 11 healthy male subjects (age, 25 ± 4 years; height, 178 ± 6 cm; body mass, 74 ± 8 kg; bench press 1RM, 76 ± 19 kg) underwent 6 sessions. Two control sessions were conducted to determine both bench press 1RM and power (6 repetitions at 50% 1RM). The 4 experimental sessions were composed of a 1RM exercise followed by power sets with different recovery intervals (1, 3, 5, and 7 minutes), performed on different days, and determined randomly. Power values were measured via Peak Power equipment (Cefise, Nova Odessa, São Paulo, Brazil). The conditions were compared using an analysis of variance with repeated measures, followed by a Tukey test. The significance level was set at p < 0.05. There was a significant increase in PAP in concentric contractions after 7 minutes of recovery compared with the control and 1-minute recovery conditions (p < 0.05). Our results indicated that 7 minutes of recovery has generated an increase in PAP in bench press and that such a strategy could be applied as an interesting alternative to enhance the performance in tasks aimed at increasing upper-body power performance.

Women's Learning in Contract Work: Practicing Contradictions in Boundaryless Conditions

ERIC Educational Resources Information Center

Fenwick, Tara

2008-01-01

The general rise in contractors, particularly among knowledge workers negotiating "boundaryless" employment conditions, has generated interest in the nature and forms of contract work. This article explores the learning of contract workers as they negotiate these conditions, with a focus on women. Drawing from a qualitative study of…

Surface-EMG analysis for the quantification of thigh muscle dynamic co-contractions during normal gait.

PubMed

Strazza, Annachiara; Mengarelli, Alessandro; Fioretti, Sandro; Burattini, Laura; Agostini, Valentina; Knaflitz, Marco; Di Nardo, Francesco

2017-01-01

The research purpose was to quantify the co-contraction patterns of quadriceps femoris (QF) vs. hamstring muscles during free walking, in terms of onset-offset muscular activation, excitation intensity, and occurrence frequency. Statistical gait analysis was performed on surface-EMG signals from vastus lateralis (VL), rectus femoris (RF), and medial hamstrings (MH), in 16315 strides walked by 30 healthy young adults. Results showed full superimpositions of MH with both VL and RF activity from terminal swing, 80 to 100% of gait cycle (GC), to the successive loading response (≈0-15% of GC), in around 90% of the considered strides. A further superimposition was detected during the push-off phase both between VL and MH activation intervals (38.6±12.8% to 44.1±9.6% of GC) in 21.9±13.6% of strides, and between RF and MH activation intervals (45.9±5.3% to 50.7±9.7 of GC) in 32.7±15.1% of strides. These findings led to identify three different co-contractions among QF and hamstring muscles during able-bodied walking: in early stance (in ≈90% of strides), in push-off (in 25-30% of strides) and in terminal swing (in ≈90% of strides). The co-contraction in terminal swing is the one with the highest levels of muscle excitation intensity. To our knowledge, this analysis represents the first attempt for quantification of QF/hamstring muscles co-contraction in young healthy subjects during normal gait, able to include the physiological variability of the phenomenon. Copyright © 2016 Elsevier B.V. All rights reserved.

Oxygen Generating Biomaterials Preserve Skeletal Muscle Homeostasis under Hypoxic and Ischemic Conditions

PubMed Central

Ward, Catherine L.; Corona, Benjamin T.; Yoo, James J.; Harrison, Benjamin S.; Christ, George J.

2013-01-01

Provision of supplemental oxygen to maintain soft tissue viability acutely following trauma in which vascularization has been compromised would be beneficial for limb and tissue salvage. For this application, an oxygen generating biomaterial that may be injected directly into the soft tissue could provide an unprecedented treatment in the acute trauma setting. The purpose of the current investigation was to determine if sodium percarbonate (SPO), an oxygen generating biomaterial, is capable of maintaining resting skeletal muscle homeostasis under otherwise hypoxic conditions. In the current studies, a biologically and physiologically compatible range of SPO (1–2 mg/mL) was shown to: 1) improve the maintenance of contractility and attenuate the accumulation of HIF1α, depletion of intramuscular glycogen, and oxidative stress (lipid peroxidation) that occurred following ∼30 minutes of hypoxia in primarily resting (duty cycle = 0.2 s train/120 s contraction interval <0.002) rat extensor digitorum longus (EDL) muscles in vitro (95% N2–5% CO2, 37°C); 2) attenuate elevations of rat EDL muscle resting tension that occurred during contractile fatigue testing (3 bouts of 25 100 Hz tetanic contractions; duty cycle = 0.2 s/2 s = 0.1) under oxygenated conditions in vitro (95% O2–5% CO2, 37°C); and 3) improve the maintenance of contractility (in vivo) and prevent glycogen depletion in rat tibialis anterior (TA) muscle in a hindlimb ischemia model (i.e., ligation of the iliac artery). Additionally, injection of a commercially available lipid oxygen-carrying compound or the components (sodium bicarbonate and hydrogen peroxide) of 1 mg/mL SPO did not improve EDL muscle contractility under hypoxic conditions in vitro. Collectively, these findings demonstrate that a biological and physiological concentration of SPO (1–2 mg/mL) injected directly into rat skeletal muscle (EDL or TA muscles) can partially preserve resting skeletal muscle homeostasis under hypoxic conditions. PMID:23991116

Mechanics and contraction dynamics of single platelets and implications for clot stiffening

NASA Astrophysics Data System (ADS)

Lam, Wilbur A.; Chaudhuri, Ovijit; Crow, Ailey; Webster, Kevin D.; Li, Tai-De; Kita, Ashley; Huang, James; Fletcher, Daniel A.

2011-01-01

Platelets interact with fibrin polymers to form blood clots at sites of vascular injury. Bulk studies have shown clots to be active materials, with platelet contraction driving the retraction and stiffening of clots. However, neither the dynamics of single-platelet contraction nor the strength and elasticity of individual platelets, both of which are important for understanding clot material properties, have been directly measured. Here we use atomic force microscopy to measure the mechanics and dynamics of single platelets. We find that platelets contract nearly instantaneously when activated by contact with fibrinogen and complete contraction within 15 min. Individual platelets can generate an average maximum contractile force of 29 nN and form adhesions stronger than 70 nN. Our measurements show that when exposed to stiffer microenvironments, platelets generated higher stall forces, which indicates that platelets may be able to contract heterogeneous clots more uniformly. The high elasticity of individual platelets, measured to be 10 kPa after contraction, combined with their high contractile forces, indicates that clots may be stiffened through direct reinforcement by platelets as well as by strain stiffening of fibrin under tension due to platelet contraction. These results show how the mechanosensitivity and mechanics of single cells can be used to dynamically alter the material properties of physiologic systems.

Force development and intracellular Ca2+ in intact cardiac muscles from gravin mutant mice.

PubMed

Li, Zhitao; Singh, Sonal; Suryavanshi, Santosh V; Ding, Wengang; Shen, Xiaoxu; Wijaya, Cori S; Gao, Wei Dong; McConnell, Bradley K

2017-07-15

Gravin (AKAP12) is an A-kinase-anchoring-protein that scaffolds protein kinase A (PKA), β 2 -adrenergic receptor (β 2 -AR), protein phosphatase 2B and protein kinase C. Gravin facilitates β 2 -AR-dependent signal transduction through PKA to modulate cardiac excitation-contraction coupling and its removal positively affects cardiac contraction. Trabeculae from the right ventricles of gravin mutant (gravin-t/t) mice were employed for force determination. Simultaneously, corresponding intracellular Ca 2+ transient ([Ca 2+ ] i ) were measured. Twitch force (T f )-interval relationship, [Ca 2+ ] i -interval relationship, and the rate of decay of post-extrasysolic potentiation (R f ) were also obtained. Western blot analysis were performed to correlate sarcomeric protein expression with alterations in calcium cycling between the WT and gravin-t/t hearts. Gravin-t/t muscles had similar developed force compared to WT muscles despite having lower [Ca 2+ ] i at any given external Ca 2+ concentration ([Ca 2+ ] o ). The time to peak force and peak [Ca 2+ ] i were slower and the time to 75% relaxation was significantly prolonged in gravin-t/t muscles. Both T f -interval and [Ca 2+ ] i -interval relations were depressed in gravin-t/t muscles. R f , however, did not change. Furthermore, Western blot analysis revealed decreased ryanodine receptor (RyR2) phosphorylation in gravin-t/t hearts. Gravin-t/t cardiac muscle exhibits increased force development in responsiveness to Ca 2+ . The Ca 2+ cycling across the SR appears to be unaltered in gravin-t/t muscle. Our study suggests that gravin is an important component of cardiac contraction regulation via increasing myofilament sensitivity to calcium. Further elucidation of the mechanism can provide insights to role of gravin if any in the pathophysiology of impaired contractility. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of axisymmetric contractions on turbulence of various scales

NASA Technical Reports Server (NTRS)

Tan-Atichat, J.; Nagib, H. M.; Drubka, R. E.

1980-01-01

Digitally acquired and processed results from an experimental investigation of grid generated turbulence of various scales through and downstream of nine matched cubic contour contractions ranging in area ratio from 2 to 36, and in length to inlet diameter ratio from 0.25 to 1.50 are reported. An additional contraction with a fifth order contour was also utilized for studying the shape effect. Thirteen homogeneous and nearly isotropic test flow conditions with a range of turbulence intensities, length scales and Reynolds numbers were generated and used to examine the sensitivity of the contractions to upstream turbulence. The extent to which the turbulence is altered by the contraction depends on the incoming turbulence scales, the total strain experienced by the fluid, as well as the contraction ratio and the strain rate. Varying the turbulence integral scale influences the transverse turbulence components more than the streamwise component. In general, the larger the turbulence scale, the lesser the reduction in the turbulence intensity of the transverse components. Best agreement with rapid distortion theory was obtained for large scale turbulence, where viscous decay over the contraction length was negligible, or when a first order correction for viscous decay was applied to the results.

Effect of muscle mass and intensity of isometric contraction on heart rate.

PubMed

Gálvez, J M; Alonso, J P; Sangrador, L A; Navarro, G

2000-02-01

The purpose of this study was to determine the effect of muscle mass and the level of force on the contraction-induced rise in heart rate. We conducted an experimental study in a sample of 28 healthy men between 20 and 30 yr of age (power: 95%, alpha: 5%). Smokers, obese subjects, and those who performed regular physical activity over a certain amount of energetic expenditure were excluded from the study. The participants exerted two types of isometric contractions: handgrip and turning a 40-cm-diameter wheel. Both were sustained to exhaustion at 20 and 50% of maximal force. Twenty-five subjects finished the experiment. Heart rate increased a mean of 15.1 beats/min [95% confidence interval (CI): 5.5-24.6] from 20 to 50% handgrip contractions, and 20.7 beats/min (95% CI: 11.9-29.5) from 20 to 50% wheel-turn contractions. Heart rate also increased a mean of 13.3 beats/min (95% CI: 10.4-16.1) from handgrip to wheel-turn contractions at 20% maximal force, and 18.9 beats/min (95% CI: 9. 8-28.0) from handgrip to wheel-turn contractions at 50% maximal force. We conclude that the magnitude of the heart rate increase during isometric exercise is related to the intensity of the contraction and the mass of the contracted muscle.

Committing to coal and gas: Long-term contracts, regulation, and fuel switching in power generation

NASA Astrophysics Data System (ADS)

Rice, Michael

Fuel switching in the electricity sector has important economic and environmental consequences. In the United States, the increased supply of gas during the last decade has led to substantial switching in the short term. Fuel switching is constrained, however, by the existing infrastructure. The power generation infrastructure, in turn, represents commitments to specific sources of energy over the long term. This dissertation explores fuel contracts as the link between short-term price response and long-term plant investments. Contracting choices enable power plant investments that are relationship-specific, often regulated, and face uncertainty. Many power plants are subject to both hold-up in investment and cost-of-service regulation. I find that capital bias is robust when considering either irreversibility or hold-up due to the uncertain arrival of an outside option. For sunk capital, the rental rate is inappropriate for determining capital bias. Instead, capital bias depends on the regulated rate of return, discount rate, and depreciation schedule. If policies such as emissions regulations increase fuel-switching flexibility, this can lead to capital bias. Cost-of-service regulation can shorten the duration of a long-term contract. From the firm's perspective, the existing literature provides limited guidance when bargaining and writing contracts for fuel procurement. I develop a stochastic programming framework to optimize long-term contracting decisions under both endogenous and exogenous sources of hold-up risk. These typically include policy changes, price shocks, availability of fuel, and volatility in derived demand. For price risks, the optimal contract duration is the moment when the expected benefits of the contract are just outweighed by the expected opportunity costs of remaining in the contract. I prove that imposing early renegotiation costs decreases contract duration. Finally, I provide an empirical approach to show how coal contracts can limit short-term fuel switching in power production. During the era prior to shale gas and electricity market deregulation, I do not find evidence that gas generation substituted for coal in response to fuel price changes. However, I do find evidence that coal plant operations are constrained by fuel contracts. As the min-take commitment to coal increases, changes to annual coal plant output decrease. My conclusions are robust in spite of bias due to the selective reporting of proprietary coal delivery contracts by utilities.

Characterization of muscle contraction with second harmonic generation microscopy

NASA Astrophysics Data System (ADS)

Prent, Nicole

Muscle cells have the ability to change length and generate force due to orchestrated action of myosin nanomotors that cause sliding of actin filaments along myosin filaments in the sarcomeres, the fundamental contractile units, of myocytes. The correlated action of hundreds of sarcomeres is needed to produce the myocyte contractions. This study probes the molecular structure of the myofilaments and investigates the movement correlations between sarcomeres during contraction. In this study, second harmonic generation (SHG) microscopy is employed for imaging striated myocytes. Myosin filaments in striated myocytes inherently have a nonzero second-order susceptibility, [special characters omitted] and therefore generate efficient SHG. Employing polarization-in polarization-out (PIPO) SHG microscopy allows for the accurate determination of the characteristic ratio, [special characters omitted] in birefringent myocytes, which describes the structure of the myosin filament. Analysis shows that the b value at the centre of the myosin filament, where the nonlinear dipoles are better aligned, is slightly lower than the value at the edges of the filament, where there is more disorder in orientation of the nonlinear dipoles from the myosin heads. Forced stretching of myocytes resulted in an SHG intensity increase with the elongation of the sarcomere. SHG microscopy captured individual sarcomeres during contraction, allowing for the measurement of sarcomere length (SL) and SHG intensity (SI) fluctuations. The fluctuations also revealed higher SHG intensity in elongated sarcomeres. The sarcomere synchronization model (SSM) for contracting and quiescent myocytes was developed, and experimentally verified for three cases (isolated cardiomyocyte, embryonic chicken cardiomyocyte, and larva myocyte). During contraction, the action of SLs and SIs between neighbouring sarcomeres partially correlated, whereas in quiescent myocytes the SLs show an anti-correlation and the SIs have no correlations. The characteristic correlation coefficients and amplitudes were obtained for each case, allowing for the characterization of the synchronization of sarcomere movement during muscle contraction. These investigations constitute the basis for studying the structure and physiology of muscle cell contractions with polarization SHG microscopy. Live dynamic imaging of myocytes is applicable for contractility research, drug discovery, and as a diagnostic tool for monitoring muscular diseases.

A Feasibility Assessment of a Single Contracting Office for Common-User Transportation Services

DTIC Science & Technology

1990-09-01

feasibility of consolidating the contracting functions that purchase common-user transportation services and occurs within the headquarters of the three...responsible for and the dollars spent in the procurement of those services. A complete breakdown of the services purchased is in chapter three. The...34 while contracting is the process a’contracting officer completes to satisfy a funded purchase request generated in response to a identified

A Communication-Optimal Framework for Contracting Distributed Tensors

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

Rajbhandari, Samyam; NIkam, Akshay; Lai, Pai-Wei

Tensor contractions are extremely compute intensive generalized matrix multiplication operations encountered in many computational science fields, such as quantum chemistry and nuclear physics. Unlike distributed matrix multiplication, which has been extensively studied, limited work has been done in understanding distributed tensor contractions. In this paper, we characterize distributed tensor contraction algorithms on torus networks. We develop a framework with three fundamental communication operators to generate communication-efficient contraction algorithms for arbitrary tensor contractions. We show that for a given amount of memory per processor, our framework is communication optimal for all tensor contractions. We demonstrate performance and scalability of our frameworkmore » on up to 262,144 cores of BG/Q supercomputer using five tensor contraction examples.« less

Psychological contract breaches, organizational commitment, and innovation-related behaviors: a latent growth modeling approach.

PubMed

Ng, Thomas W H; Feldman, Daniel C; Lam, Simon S K

2010-07-01

This study examined the relationships among psychological contract breaches, organizational commitment, and innovation-related behaviors (generating, spreading, implementing innovative ideas at work) over a 6-month period. Results indicate that the effects of psychological contract breaches on employees are not static. Specifically, perceptions of psychological contract breaches strengthened over time and were associated with decreased levels of affective commitment over time. Further, increased perceptions of psychological contract breaches were associated with decreases in innovation-related behaviors. We also found evidence that organizational commitment mediates the relationship between psychological contract breaches and innovation-related behaviors. These results highlight the importance of examining the nomological network of psychological contract breaches from a change perspective.

Chapter 34: Geology and petroleum potential of the rifted margins of the Canada Basin

USGS Publications Warehouse

Houseknecht, D.W.; Bird, K.J.

2011-01-01

Three sides of the Canada Basin are bordered by high-standing, conjugate rift shoulders of the Chukchi Borderland, Alaska and Canada. The Alaska and Canada margins are mantled with thick, growth-faulted sediment prisms, and the Chukchi Borderland contains only a thin veneer of sediment. The rift-margin strata of Alaska and Canada reflect the tectonics and sediment dispersal systems of adjacent continental regions whereas the Chukchi Borderland was tectonically isolated from these sediment dispersal systems. Along the eastern Alaska-southern Canada margin, termed herein the 'Canning-Mackenzie deformed margin', the rifted margin is deformed by ongoing Brooks Range tectonism. Additional contractional structures occur in a gravity fold belt that may be present along the entire Alaska and Canada margins of the Canada Basin. Source-rock data inboard of the rift shoulders and regional palaeogeographic reconstructions suggest three potential source-rock intervals: Lower Cretaceous (Hauterivian-Albian), Upper Cretaceous (mostly Turonian) and Lower Palaeogene. Burial history modelling indicates favourable timing for generation from all three intervals beneath the Alaska and Canada passive margins, and an active petroleum system has been documented in the Canning-Mackenzie deformed margin. Assessment of undiscovered petroleum resources indicates the greatest potential in the Canning-Mackenzie deformed margin and significant potential in the Canada and Alaska passive margins. ?? 2011 The Geological Society of London.

Does the Momentum Flux Generated by Gravitational Contraction Drive Asymptotic Giant Branch Mass Loss?

NASA Astrophysics Data System (ADS)

Lewis, B. M.

1997-12-01

Gravitational contraction always generates a radially directed momentum flow. A particularly simple example occurs in the electron-degenerate cores of asymptotic giant branch (AGB) stars, which contract steadily under the addition of helium ashes from shell hydrogen burning. The resulting momentum flux is quantified here. And since the cores of AGB stars lack efficient momentum-cancellation mechanisms, they can maintain equilibrium by exporting their excess momentum flux to the stellar envelope, which disposes of much of it in a low velocity wind. Gravitational contraction easily accounts for the momentum flux in the solar wind, as well as the flux required to lift mass into the dust formation zone of every AGB star, whereon radiation pressure continues its ejection as a low-velocity wind. This mechanism explains the dependence of the AGB mass-loss rate on core mass; its generalization to objects with angular momentum and/or strong magnetic fields suggests a novel explanation as to why most planetary nebulae and proto-planetary nebulae exhibit axial symmetry. Quasi-static contraction is inherently biased to the generation of the maximum possible momentum flux. Its formalism is, therefore, readily adapted to providing an upper limit to the momentum flux needed to sustain mass loss when this begins from a semicontinuous rather than an impulsive process.

Grid Stiffened Structure Analysis Tool

NASA Technical Reports Server (NTRS)

1999-01-01

The Grid Stiffened Analysis Tool contract is contract performed by Boeing under NASA purchase order H30249D. The contract calls for a "best effort" study comprised of two tasks: (1) Create documentation for a composite grid-stiffened structure analysis tool, in the form of a Microsoft EXCEL spread sheet, that was developed by originally at Stanford University and later further developed by the Air Force, and (2) Write a program that functions as a NASTRAN pre-processor to generate an FEM code for grid-stiffened structure. In performing this contract, Task 1 was given higher priority because it enables NASA to make efficient use of a unique tool they already have; Task 2 was proposed by Boeing because it also would be beneficial to the analysis of composite grid-stiffened structures, specifically in generating models for preliminary design studies. The contract is now complete, this package includes copies of the user's documentation for Task 1 and a CD ROM & diskette with an electronic copy of the user's documentation and an updated version of the "GRID 99" spreadsheet.

Effect of Contraction on Turbulence and Temperature Fluctuations Generated by a Warm Grid

NASA Technical Reports Server (NTRS)

Mills, Robert R., Jr.; Corrsin, Stanley

1959-01-01

Hot-wire anemometer measurements were made of several statistical properties of approximately homogeneous and isotropic fields of turbulence and temperature fluctuations generated by a warm grid in a uniform airstream sent through a 4-to-1 contraction. These measurements were made both in the contraction and in the axisymmetric domain farther downstream. In addition to confirming the well-known turbulence anisotropy induced by strain, the data show effects on the skewnesses of both longitudinal velocity fluctuation (which has zero skewness in isotropic turbulence) and its derivative. The concomitant anisotropy in the temperature field accelerates the decay of temperature fluctuations.

Structural alterations of thin actin filaments in muscle contraction by synchrotron X-ray fiber diffraction.

PubMed

Wakabayashi, Katsuzo; Sugimoto, Yasunobu; Takezawa, Yasunori; Ueno, Yutaka; Minakata, Shiho; Oshima, Kanji; Matsuo, Tatsuhito; Kobayashi, Takakazu

2007-01-01

Strong evidence has been accumulated that the conformational changes of the thin actin filaments are occurring and playing an important role in the entire process of muscle contraction. The conformational changes and the mechanical properties of the thin actin filaments we have found by X-ray fiber diffraction on skeletal muscle contraction are explored. Recent studies on the conformational changes of regulatory proteins bound to actin filaments upon activation and in the force generation process are also described. Finally, the roles of structural alterations and dynamics of the actin filaments are discussed in conjunction with the regulation mechanism and the force generation mechanism.

Hospice agencies' hospital contract status and differing levels of hospice care.

PubMed

Chung, Kyusuk; Richards, Nicole; Burke, Sloane

2015-05-01

In response to a 2011 finding that approximately 27% of Medicare-certified hospices do not provide a single day of general inpatient care (GIP), the authors explored the extent to which hospices have contracts with hospitals for GIP. Using the 2007 National Home and Hospice Care Survey, we estimated that 1119 (32%) agencies had no contract with any hospitals in 2007 and half of those with no contract did not have a contract with a skilled nursing facility (SNF) either. As a result, these hospices were unable to provide GIP referrals for those in need of inpatient care for acute pain and symptom management. More importantly, not having a contract with a hospital was just one of the factors influencing GIP provision. In the multivariate logistic model, after controlling for contract status with a hospital and other hospice characteristics, agencies in the second quartile of hospice patient census (12-29 vs 73 or more, adjusted odds ratio = 14.10; 95% confidence interval 4.26-46.62) were independently related to providing only routine home care. These hospices are more likely to rely solely on scatter beds for GIP provision. Given that a significant portion of hospices do not have a contract with a hospital, policy makers need to understand barriers to contracts with a hospital/SNF for GIP and consider a hospice's contract status as one of the standards for hospice certification. In addition, further research is necessary to understand why hospices that do have a contract with a hospital do not make GIP referral. © The Author(s) 2014.

Physical principles demonstrate that the biceps femoris muscle relative to the other hamstring muscles exerts the most force: implications for hamstring muscle strain injuries

PubMed Central

Dolman, Bronwyn; Verrall, Geoffrey; Reid, Iain

2014-01-01

Summary Of the hamstring muscle group the biceps femoris muscle is the most commonly injured muscle in sports requiring interval sprinting. The reason for this observation is unknown. The objective of this study was to calculate the forces of all three hamstring muscles, relative to each other, during a lengthening contraction to assess for any differences that may help explain the biceps femoris predilection for injury during interval sprinting. To calculate the displacement of each individual hamstring muscle previously performed studies on cadaveric anatomical data and hamstring kinematics during sprinting were used. From these displacement calculations for each individual hamstring muscle physical principles were then used to deduce the proportion of force exerted by each individual hamstring muscle during a lengthening muscle contraction. These deductions demonstrate that the biceps femoris muscle is required to exert proportionally more force in a lengthening muscle contraction relative to the semimembranosus and semitendinosus muscles primarily as a consequence of having to lengthen over a greater distance within the same time frame. It is hypothesized that this property maybe a factor in the known observation of the increased susceptibility of the biceps femoris muscle to injury during repeated sprints where recurrent higher force is required. PMID:25506583

Physical principles demonstrate that the biceps femoris muscle relative to the other hamstring muscles exerts the most force: implications for hamstring muscle strain injuries.

PubMed

Dolman, Bronwyn; Verrall, Geoffrey; Reid, Iain

2014-07-01

Of the hamstring muscle group the biceps femoris muscle is the most commonly injured muscle in sports requiring interval sprinting. The reason for this observation is unknown. The objective of this study was to calculate the forces of all three hamstring muscles, relative to each other, during a lengthening contraction to assess for any differences that may help explain the biceps femoris predilection for injury during interval sprinting. To calculate the displacement of each individual hamstring muscle previously performed studies on cadaveric anatomical data and hamstring kinematics during sprinting were used. From these displacement calculations for each individual hamstring muscle physical principles were then used to deduce the proportion of force exerted by each individual hamstring muscle during a lengthening muscle contraction. These deductions demonstrate that the biceps femoris muscle is required to exert proportionally more force in a lengthening muscle contraction relative to the semimembranosus and semitendinosus muscles primarily as a consequence of having to lengthen over a greater distance within the same time frame. It is hypothesized that this property maybe a factor in the known observation of the increased susceptibility of the biceps femoris muscle to injury during repeated sprints where recurrent higher force is required.

Detrusor expulsive strength is preserved, but responsiveness to bladder filling and urinary sensitivity is diminished in the aging mouse

PubMed Central

DeAngelis, Anthony; Kuchel, George A.

2012-01-01

The prevalence of urinary symptoms increases with age and is a significant source of distress, morbidity, and expense in the elderly. Recent evidence suggests that symptoms in the aged may result from sensory dysfunction, rather than abnormalities of detrusor performance. Therefore, we employed a pressure/flow multichannel urethane-anesthetized mouse cystometry model to test the hypothesis that in vivo detrusor performance does not degrade with aging. Secondarily, we sought to evaluate sensory responsiveness to volume using pressure-volume data generated during bladder filling. Cystometric data from 2-, 12-, 22-, and 26-mo-old female C57BL6 mice were compared. All 2- and 12-mo-old mice, 66% of 22-mo-old mice, and 50% of 26-mo-old mice responded to continuous bladder filling with periodic reflex voiding. Abdominal wall contraction with voiding had a minimal contribution to expulsive pressure, whereas compliance pressure was a significant contributor. Maximum bladder pressure, estimated detrusor pressure, detrusor impulse (pressure-time integral), as well as indices of detrusor power and work, did not decrease with aging. Bladder precontraction pressures decreased, compliance increased, and nonvoiding contraction counts did not change with increasing age. Intervoid intervals, per-void volumes, and voiding flow rates increased with age. Calculations approximating wall stress during filling suggested loss of bladder volume sensitivity with increasing age. We conclude that aging is associated with an impaired ability to respond to the challenge of continuous bladder filling with cyclic voiding, yet among responsive animals, voiding detrusor contraction strength does not degrade with aging in this murine model. Furthermore, indirect measures suggest that bladder volume sensitivity is diminished. Thus, changes in homeostatic reserve and peripheral and/or central sensory mechanisms may be important contributors to aging-associated changes in bladder function. PMID:22204955

Computer assisted generation of the matrix elements between contracted wavefunctions in a Complete Active Space scheme

NASA Astrophysics Data System (ADS)

Angeli, C.; Cimiraglia, R.

2005-02-01

Starting from a CAS-SCF calculation a sequence of contracted functions can be generated by applying strings of spin-traced replacement operators to the CAS-SCF solution. The laborious task of producing the Hamiltonian matrix elements between such functions can be substantially reduced making use of a computer algebra system. An implementation employing the MuPAD system is presented and illustrated.

Utilizing Physiological Principles of Motor Unit Recruitment to Reduce Fatigability of Electrically-Evoked Contractions: A Narrative Review.

PubMed

Barss, Trevor S; Ainsley, Emily N; Claveria-Gonzalez, Francisca C; Luu, M John; Miller, Dylan J; Wiest, Matheus J; Collins, David F

2018-04-01

Neuromuscular electrical stimulation (NMES) is used to produce contractions to restore movement and reduce secondary complications for individuals experiencing motor impairment. NMES is conventionally delivered through a single pair of electrodes over a muscle belly or nerve trunk using short pulse durations and frequencies between 20 and 40Hz (conventional NMES). Unfortunately, the benefits and widespread use of conventional NMES are limited by contraction fatigability, which is in large part because of the nonphysiological way that contractions are generated. This review provides a summary of approaches designed to reduce fatigability during NMES, by using physiological principles that help minimize fatigability of voluntary contractions. First, relevant principles of the recruitment and discharge of motor units (MUs) inherent to voluntary contractions and conventional NMES are introduced, and the main mechanisms of fatigability for each contraction type are briefly discussed. A variety of NMES approaches are then described that were designed to reduce fatigability by generating contractions that more closely mimic voluntary contractions. These approaches include altering stimulation parameters, to recruit MUs in their physiological order, and stimulating through multiple electrodes, to reduce MU discharge rates. Although each approach has unique advantages and disadvantages, approaches that minimize MU discharge rates hold the most promise for imminent translation into rehabilitation practice. The way that NMES is currently delivered limits its utility as a rehabilitative tool. Reducing fatigability by delivering NMES in ways that better mimic voluntary contractions holds promise for optimizing the benefits and widespread use of NMES-based programs. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Inhibitory effects of different ATP-sensitive potassium channel openers on electrically generated and carbachol-induced contractions of porcine and human detrusor muscle.

PubMed

Badawi, Jasmin Katrin; Ding, Andrea; Bross, Stephan

2008-02-01

The inhibitory effects of different potassium channel openers (PCOs) on electrically generated and carbachol-induced contractions of porcine and human detrusor muscle were examined. PCOs could be an interesting substance class for treatment of detrusor overactivity. Experiments were performed on muscle strips suspended in a tissue bath. Human tissue originated from patients who underwent total cystectomy. The concentration-relaxation curves of the first-generation PCOs cromakalim and pinacidil and the untypical PCO minoxidil were performed using carbachol-precontracted detrusor muscle strips of pigs and humans. Additionally, the inhibitory effects of cromakalim, pinacidil and minoxidil on electrically generated contractions of porcine detrusor muscle were examined. Furthermore, the inhibitory effect of the second-generation, bladder-selective PCO ZM 226600 on electrically generated contractions of the human detrusor muscle was determined. Frequency-response curves were performed before and after incubation with one PCO used in two different concentrations. In humans, cromakalim and pinacidil led to a maximum decrease of 73.5 and 68.4% and showed mean pD2 values of 6.65 and 5.5, respectively. In pigs, cromakalim and pinacidil led to a maximum decrease of 90.6 and 93.6% and showed mean pD2 values of 6.39 and 5.01, respectively. Minoxidil did not significantly decrease the precontraction at the highest used concentration in both species. Cromakalim exhibited the biggest inhibitory effect being significant at 10(-5) and 10(-6) M. Pinacidil showed only a significant inhibitory effect at 10(-5) M which was smaller than that of cromakalim. At 3 x 10(-6) M only a very small effect occurred at 1 Hz. Minoxidil did not inhibit the contractions at both examined concentrations except for a very small effect at 1 Hz. In humans, ZM 226600 exhibited at 10(-6) and 10(-5) M a significant inhibitory effect. At 10(-7) M it was only significant at one frequency.

Cardiac cycle-dependent left atrial dynamics: implications for catheter ablation of atrial fibrillation.

PubMed

Patel, Amit R; Fatemi, Omid; Norton, Patrick T; West, J Jason; Helms, Adam S; Kramer, Christopher M; Ferguson, John D

2008-06-01

Left atrial (LA) volume determines prognosis and response to therapy for atrial fibrillation. Integration of electroanatomic maps with three-dimensional images rendered from computed tomography and magnetic resonance imaging (MRI) is used to facilitate atrial fibrillation ablation. The purpose of this study was to measure LA volume changes and regional motion during the cardiac cycle that might affect the accuracy of image integration and to determine their relationship to standard LA volume measurements. MRI was performed in 30 patients with paroxysmal atrial fibrillation. LA time-volume curves were generated and used to divide LA ejection fraction into pumping ejection fraction and conduit ejection fraction and to determine maximum LA volume (LA(max)) and preatrial contraction volume. LA volume was measured using an MRI angiogram and traditional geometric models from echocardiography (area-length model and ellipsoid model). In-plane displacement of the pulmonary veins, anterior left atrium, mitral annulus, and LA appendage was measured. LA(max) was 107 +/- 36 mL and occurred at 42% +/- 5% of the R-R interval. Preatrial contraction volume was 86 +/- 34 mL and occurred at 81% +/- 4% of the R-R interval. LA ejection fraction was 45% +/- 10%, and pumping ejection fraction was 31% +/- 10%. LA volume measurements made from MRI angiogram, area-length model, and ellipsoid model underestimated LA(max) by 21 +/- 25 mL, 16 +/- 26 mL, and 35 +/- 22 mL, respectively. Anterior LA, mitral annulus, and LA appendage were significantly displaced during the cardiac cycle (8.8 +/- 2.0 mm, 13.2 +/- 3.8 mm, and 10.2 +/- 3.4 mm, respectively); the pulmonary veins were not displaced. LA volume changes significantly during the cardiac cycle, and substantial regional variation in LA motion exists. Standard measurements of LA volume significantly underestimate LA(max) compared to the gold standard measure of three-dimensional volumetrics.

Preceding muscle activity influences motor unit discharge and rate of torque development during ballistic contractions in humans

PubMed Central

Van Cutsem, Michaël; Duchateau, Jacques

2005-01-01

To investigate the effect of initial conditions on the modulation of motor unit discharge during fast voluntary contractions, we compared ballistic isometric contractions of the ankle dorsiflexor muscles that were produced from either a resting state or superimposed on a sustained contraction. The torque of the dorsiflexors and the surface and intramuscular EMGs from the tibialis anterior were recorded. The results showed that the performance of a ballistic contraction from a sustained contraction (∼25% maximal voluntary contraction (MVC)) had a negative effect on the maximal rate of torque development. Although the electromechanical delay was shortened, the EMG activity during the ballistic contraction was less synchronized. These observations were associated with a significant decline in the average discharge rate of single motor units (89.8 ± 3.8 versus 115 ± 5.8 Hz) and in the percentage of units (6.2 versus 15.5% of the whole sample) that exhibited double discharges at brief intervals (= 5 ms). High-threshold units that were not recruited during the sustained contraction displayed the same activation pattern, which indicates that the mechanisms responsible for the decline in discharge rate were not restricted to previously activated units, but appear to influence the entire motor unit pool. When a premotor silent period (SP) was observed at the transition from the sustained muscular activity to the ballistic contraction (19% of the trials), these adjustments in motor unit activity were not present, and the ballistic contractions were similar to those performed from a resting state. Together, these results indicate that initial conditions can influence the capacity for motor unit discharge rate and hence the performance of a fast voluntary contraction. PMID:15539402

48 CFR 1913.505-2 - Board order forms in lieu of Optional and Standard Forms.

Code of Federal Regulations, 2011 CFR

2011-10-01

... BROADCASTING BOARD OF GOVERNORS CONTRACTING METHODS AND CONTRACT TYPES SMALL PURCHASES AND OTHER SIMPLIFIED...-case basis, in order to accommodate computer-generated purchase order forms. Exception approval for...

48 CFR 1913.505-2 - Board order forms in lieu of Optional and Standard Forms.

Code of Federal Regulations, 2010 CFR

2010-10-01

... BROADCASTING BOARD OF GOVERNORS CONTRACTING METHODS AND CONTRACT TYPES SMALL PURCHASES AND OTHER SIMPLIFIED...-case basis, in order to accommodate computer-generated purchase order forms. Exception approval for...

Task-dependent activation of distinct fast and slow(er) motor pathways during motor imagery.

PubMed

Keller, Martin; Taube, Wolfgang; Lauber, Benedikt

2018-02-22

Motor imagery and actual movements share overlapping activation of brain areas but little is known about task-specific activation of distinct motor pathways during mental simulation of movements. For real contractions, it was demonstrated that the slow(er) motor pathways are activated differently in ballistic compared to tonic contractions but it is unknown if this also holds true for imagined contractions. The aim of the present study was to assess the activity of fast and slow(er) motor pathways during mentally simulated movements of ballistic and tonic contractions. H-reflexes were conditioned with transcranial magnetic stimulation at different interstimulus intervals to assess the excitability of fast and slow(er) motor pathways during a) the execution of tonic and ballistic contractions, b) motor imagery of these contraction types, and c) at rest. In contrast to the fast motor pathways, the slow(er) pathways displayed a task-specific activation: for imagined ballistic as well as real ballistic contractions, the activation was reduced compared to rest whereas enhanced activation was found for imagined tonic and real tonic contractions. This study provides evidence that the excitability of fast and slow(er) motor pathways during motor imagery resembles the activation pattern observed during real contractions. The findings indicate that motor imagery results in task- and pathway-specific subliminal activation of distinct subsets of neurons in the primary motor cortex. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Radial stiffness characteristics of the overlap regions of sarcomeres in isolated skeletal myofibrils in pre-force generating state.

PubMed

Miyashiro, Daisuke; Ohtsuki, Misato; Shimamoto, Yuta; Wakayama, Jun'ichi; Kunioka, Yuki; Kobayashi, Takakazu; Ishiwata, Shin'ichi; Yamada, Takenori

2017-01-01

We have studied the stiffness of myofilament lattice in sarcomeres in the pre-force generating state, which was realized by a relaxing reagent, BDM (butane dione monoxime). First, the radial stiffness for the overlap regions of sarcomeres of isolated single myofibrils was estimated from the resulting decreases in diameter by osmotic pressure applied with the addition of Dextran. Then, the radial stiffness was also estimated from force-distance curve measurements with AFM technology. The radial stiffness for the overlap regions thus obtained was composed of a soft and a rigid component. The soft component visco-elastically changed in a characteristic fashion depending on the physiological conditions of myofibrils, suggesting that it comes from cross-bridge structures. BDM treatments significantly affected the soft radial component of contracting myofibrils depending on the approach velocity of cantilever: It was nearly equal to that in the contracting state at high approach velocity, whereas as low as that in the relaxing state at low approach velocity. However, comparable BDM treatments greatly suppressed the force production and the axial stiffness in contracting glycerinated muscle fibers and also the sliding velocity of actin filaments in the in vitro motility assay. Considering that BDM shifts the cross-bridge population from force generating to pre-force generating states in contracting muscle, the obtained results strongly suggest that cross-bridges in the pre-force generating state are visco-elastically attached to the thin filaments in such a binding manner that the axial stiffness is low but the radial stiffness significantly high similar to that in force generating state.

Stiffness, working stroke, and force of single-myosin molecules in skeletal muscle: elucidation of these mechanical properties via nonlinear elasticity evaluation.

PubMed

Kaya, Motoshi; Higuchi, Hideo

2013-11-01

In muscles, the arrays of skeletal myosin molecules interact with actin filaments and continuously generate force at various contraction speeds. Therefore, it is crucial for myosin molecules to generate force collectively and minimize the interference between individual myosin molecules. Knowledge of the elasticity of myosin molecules is crucial for understanding the molecular mechanisms of muscle contractions because elasticity directly affects the working and drag (resistance) force generation when myosin molecules are positively or negatively strained. The working stroke distance is also an important mechanical property necessary for elucidation of the thermodynamic efficiency of muscle contractions at the molecular level. In this review, we focus on these mechanical properties obtained from single-fiber and single-molecule studies and discuss recent findings associated with these mechanical properties. We also discuss the potential molecular mechanisms associated with reduction of the drag effect caused by negatively strained myosin molecules.

Effect of combined actions of hip adduction/abduction on the force generation and maintenance of pelvic floor muscles in healthy women

PubMed Central

Amorim, Amanda C.; Cacciari, Licia P.; Passaro, Anice C.; Silveira, Simone R. B.; Amorim, Cesar F.; Loss, Jefferson F.

2017-01-01

Pelvic floor muscle (PFM) force and coordination are related to urinary incontinence severity and to sexual satisfaction. Health professionals frequently combine classic PFM exercises with hip adduction/abduction contraction to treat these disorders, but the real benefits of this practice are still unknown. Based on a theoretical anatomy approach whereby the levator ani muscle is inserted into the obturator internus myofascia and in which force generated by hip movements should increase the contraction quality of PFMs, our aim was to investigate the effects of isometric hip adduction and abduction on PFM force generation. Twenty healthy, nulliparous women were evaluated using two strain-gauge dynamometers (one cylinder-like inside the vaginal cavity, and the other measuring hip adduction/abduction forces around both thighs) while performing three different tasks: (a) isolated PFM contraction; (b) PFM contraction combined with hip adduction (30% and 50% maximum hip force); and (c) PFM contraction combined with hip abduction (30% and 50% maximum hip force). Data were sampled at 100Hz and subtracted from the offset if existent. We calculated a gradient between the isolated PFM contraction and each hip condition (Δ Adduction and Δ Abduction) for all variables: Maximum force (N), instant of maximum-force occurrence (s), mean force in an 8-second window (N), and PFM force loss (N.s). We compared both conditions gradients in 30% and 50% by paired t-tests. All variables did not differ between hip conditions both in 30% and 50% of maximum hip force (p>.05). PFM contraction combined with isometric hip abduction did not increase vaginal force in healthy and nulliparous women compared to PFM contraction combined with isometric hip adduction. Therefore, so far, the use of hip adduction or abduction in PFM training and treatments are not justified for improving PFM strength and endurance. PMID:28542276

Effect of combined actions of hip adduction/abduction on the force generation and maintenance of pelvic floor muscles in healthy women.

PubMed

Amorim, Amanda C; Cacciari, Licia P; Passaro, Anice C; Silveira, Simone R B; Amorim, Cesar F; Loss, Jefferson F; Sacco, Isabel C N

2017-01-01

Pelvic floor muscle (PFM) force and coordination are related to urinary incontinence severity and to sexual satisfaction. Health professionals frequently combine classic PFM exercises with hip adduction/abduction contraction to treat these disorders, but the real benefits of this practice are still unknown. Based on a theoretical anatomy approach whereby the levator ani muscle is inserted into the obturator internus myofascia and in which force generated by hip movements should increase the contraction quality of PFMs, our aim was to investigate the effects of isometric hip adduction and abduction on PFM force generation. Twenty healthy, nulliparous women were evaluated using two strain-gauge dynamometers (one cylinder-like inside the vaginal cavity, and the other measuring hip adduction/abduction forces around both thighs) while performing three different tasks: (a) isolated PFM contraction; (b) PFM contraction combined with hip adduction (30% and 50% maximum hip force); and (c) PFM contraction combined with hip abduction (30% and 50% maximum hip force). Data were sampled at 100Hz and subtracted from the offset if existent. We calculated a gradient between the isolated PFM contraction and each hip condition (Δ Adduction and Δ Abduction) for all variables: Maximum force (N), instant of maximum-force occurrence (s), mean force in an 8-second window (N), and PFM force loss (N.s). We compared both conditions gradients in 30% and 50% by paired t-tests. All variables did not differ between hip conditions both in 30% and 50% of maximum hip force (p>.05). PFM contraction combined with isometric hip abduction did not increase vaginal force in healthy and nulliparous women compared to PFM contraction combined with isometric hip adduction. Therefore, so far, the use of hip adduction or abduction in PFM training and treatments are not justified for improving PFM strength and endurance.

Commercial nuclear power 1990

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

Not Available

1990-09-28

This report presents the status at the end of 1989 and the outlook for commercial nuclear capacity and generation for all countries in the world with free market economies (FME). The report provides documentation of the US nuclear capacity and generation projections through 2030. The long-term projections of US nuclear capacity and generation are provided to the US Department of Energy's (DOE) Office of Civilian Radioactive Waste Management (OCRWM) for use in estimating nuclear waste fund revenues and to aid in planning the disposal of nuclear waste. These projections also support the Energy Information Administration's annual report, Domestic Uranium Miningmore » and Milling Industry: Viability Assessment, and are provided to the Organization for Economic Cooperation and Development. The foreign nuclear capacity projections are used by the DOE uranium enrichment program in assessing potential markets for future enrichment contracts. The two major sections of this report discuss US and foreign commercial nuclear power. The US section (Chapters 2 and 3) deals with (1) the status of nuclear power as of the end of 1989; (2) projections of nuclear capacity and generation at 5-year intervals from 1990 through 2030; and (3) a discussion of institutional and technical issues that affect nuclear power. The nuclear capacity projections are discussed in terms of two projection periods: the intermediate term through 2010 and the long term through 2030. A No New Orders case is presented for each of the projection periods, as well as Lower Reference and Upper Reference cases. 5 figs., 30 tabs.« less

Rheosensing by impulsive cells at intermediate Reynolds numbers

NASA Astrophysics Data System (ADS)

Mathijssen, Arnold; Bhamla, Saad; Prakash, Manu

2017-11-01

For aquatic organisms, mechanical signals are often carried by the surrounding liquid, through viscous and inertial forces. Here we consider a unicellular yet millimetric ciliate, Spirostomum ambiguum, as a model organism to study hydrodynamic sensing. This protist typically swims at moderate Reynolds numbers, Re < 0.5, but upon stimulation it surges to Re > 100 during impulsive contractions where its elongated body recoils within milliseconds. First, using high-speed PIV and an electrophysiology setup, we deliver controlled voltage pulses to induce these rapid contractions and visualise the vortex flows generated thereby. By comparing these measurements with CFD simulations the range of these hydrodynamic ``signals'' is characterized. Second, we probe the mechano-sensing of the organism with externally applied flows and find a critical shear rate necessary to trigger a contraction. The combination of high Re flow generation and rheosensing could facilitate intercellular communication over large distances. Please also see our other talk ``Collective hydrodynamic communication through ultra-fast contractions''.

In vitro contraction of cytokinetic ring depends on myosin II but not on actin dynamics.

PubMed

Mishra, Mithilesh; Kashiwazaki, Jun; Takagi, Tomoko; Srinivasan, Ramanujam; Huang, Yinyi; Balasubramanian, Mohan K; Mabuchi, Issei

2013-07-01

Cytokinesis in many eukaryotes involves the contraction of an actomyosin-based contractile ring. However, the detailed mechanism of contractile ring contraction is not fully understood. Here, we establish an experimental system to study contraction of the ring to completion in vitro. We show that the contractile ring of permeabilized fission yeast cells undergoes rapid contraction in an ATP- and myosin-II-dependent manner in the absence of other cytoplasmic constituents. Surprisingly, neither actin polymerization nor its disassembly is required for contraction of the contractile ring, although addition of exogenous actin-crosslinking proteins blocks ring contraction. Using contractile rings generated from fission yeast cytokinesis mutants, we show that not all proteins required for assembly of the ring are required for its contraction in vitro. Our work provides the beginnings of the definition of a minimal contraction-competent cytokinetic ring apparatus.

DELTA-DIESEL ENGINE LIGHT TRUCK APPLICATION Contract DE-FC05-97OR22606 Final Report

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

Hakim, Nabil Balnaves, Mike

2003-05-27

DELTA Diesel Engine Light Truck Application End of Contract Report DE-FC05-97-OR22606 EXECUTIVE SUMMARY This report is the final technical report of the Diesel Engine Light Truck Application (DELTA) program under contract DE-FC05-97-OR22606. During the course of this contract, Detroit Diesel Corporation analyzed, designed, tooled, developed and applied the ''Proof of Concept'' (Generation 0) 4.0L V-6 DELTA engine and designed the successor ''Production Technology Demonstration'' (Generation 1) 4.0L V-6 DELTA engine. The objectives of DELTA Program contract DE-FC05-97-OR22606 were to: Demonstrate production-viable diesel engine technologies, specifically intended for the North American LDT and SUV markets; Demonstrate emissions compliance with significant fuelmore » economy advantages. With a clean sheet design, DDC produced the DELTA engine concept promising the following attributes: 30-50% improved fuel economy; Low cost; Good durability and reliability; Acceptable noise, vibration and harshness (NVH); State-of-the-art features; Even firing, 4 valves per cylinder; High pressure common rail fuel system; Electronically controlled; Turbocharged, intercooled, cooled EGR; Extremely low emissions via CLEAN Combustion{copyright} technology. To demonstrate the engine technology in the SUV market, DDC repowered a 1999 Dodge Durango with the DELTA Generation 0 engine. Fuel economy improvements were approximately 50% better than the gasoline engine replaced in the vehicle.« less

Office of Inspector General audit report on Project Hanford management contract costs and performance

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

NONE

1998-11-01

On August 6, 1996, the Richland Operations Office (Richland) awarded the Project Hanford Management Contract (Management Contract) to Fluor Daniel Hanford, Inc. (Fluor Daniel). This performance-based, 5-year contract to support cleanup of the Department of Energy`s (DOE) Hanford Site (Hanford) contained performance goals or expectations related to the stabilization, transition, and diversification of the Tri-Cities` economy near Hanford in southeastern Washington. One of these economic goals was that Fluor Daniel and its major subcontractors would help generate 3,000 new, non-Hanford, private sector jobs that would help stabilize and diversify the Tri-Cities` economy. The contract specifically called for Fluor Daniel tomore » help generate 200 jobs, establish an investment fund, and bring 6 new growth-oriented enterprise companies to the Tri-Cities by the end of Fiscal Year (FY) 1997. The objective of the audit was to determine whether Richland was making adequate progress in stabilizing and diversifying the economy of the Tri-Cities by creating 3,000 new, non-Hanford jobs within 5 years. Accordingly, the author examined the progress made in FY 1997, which was the first year of the Management Contract. Richland and Fluor Daniel are at risk of not meeting the Management Contract`s goals of stabilizing and diversifying the economy of the Tri-Cities because most of the new jobs created during FY 1997 were not comparable to Hanford jobs and, thus, may not sustain long-term economic goals. Therefore, Fluor Daniel has not met its expectations in the first year and is not making adequate progress toward meeting the Management Contract`s overall economic goals.« less

Paleosol sequences within Lower Permian cyclothems of Kansas: Evidence of climatic cyclicity

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

Miller, K.B.; McCahon, T.J.

The Lower Permian (Wolfcampian) cycles of Kansas are broadly similar to the better known Upper Pennsylvanian (Missourian) cyclothems of the midcontinent. The morphological features of paleosols within five successive variegated mudstone units of the Council Grove and Chase Groups have been described in detail. A consistent pattern has emerged with aridic paleosols near the bases of the mudstones intervals and vertic paleosols toward the tops. The lower paleosol profiles are typically calcareous with well-developed carbonate accumulation (Bk) horizons. These may contain carbonate nodules, rhizocretions, or less commonly calcretes (K-horizons). Drab haloed root races are a common feature of these grayishmore » reddish brown B horizons. The reddish color records oxidation under fairly well drained conditions, the underlying greenish gray horizons probably indicating the average position of the water table. Thin greenish gray to gray elluvial (E) horizons are preserved at the tops of many profiles. The upper paleosols within each variegated interval are characterized by well-developed vertic structures. Pedogenic slickensides, pseudoanticlines, and occasional gilgai result from the expansion and contraction of the soil such as occurs in a seasonal wet/dry environment. These paleosols are greenish gray to olive gray and often have abundant concertina root traces. The absence of a red oxidized horizon suggests more poorly drained conditions. The upward trend from drier, better drained soils to vertic, poorly drained soils could have been generated by short-term climate change toward increasing, though still seasonal, precipitation. If so, this observation suggests that cyclic climatic change may have been an important factor in generating Lower Permian cyclothems. Such a conclusion is consistent with other evidence that the limestone and shale facies of these cyclothems were deposited in consistently shallow depositional environments.« less

24 CFR 3280.608 - Hangers and supports.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Hangers and supports. (a) Strains and stresses. Piping in a plumbing system shall be installed without undue strains and stresses, and provision shall be made for expansion, contraction, and structural..., plastic drainage piping shall be supported at intervals not to exceed 4 feet and plastic water piping...

24 CFR 3280.608 - Hangers and supports.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Hangers and supports. (a) Strains and stresses. Piping in a plumbing system shall be installed without undue strains and stresses, and provision shall be made for expansion, contraction, and structural..., plastic drainage piping shall be supported at intervals not to exceed 4 feet and plastic water piping...

25 CFR 175.24 - Utility responsibilities.

Code of Federal Regulations, 2010 CFR

2010-04-01

... BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER INDIAN ELECTRIC POWER UTILITIES...; (e) Read meters or authorize the customer(s) to read meters at intervals prescribed in the operations manual, service agreement, or special contract, except in those situations where the meter cannot be read...

Green Power Partnership Long-term Contracts

EPA Pesticide Factsheets

The U.S. EPA's Green Power Partnership is a voluntary program designed to reduce the environmental impact of electricity generation by promoting renewable energy. This page lists Partners that signed a contract to purchase green power for 5 years or more.

Deregulation Impact in Negotiating a New Electrical Contract Between NASA Glenn Research Center at Lewis Field and FirstEnergy Corp., Cleveland, Ohio, USA

NASA Technical Reports Server (NTRS)

Quach, Quyen T.; Zala, Laszlo F.

2002-01-01

The governor of the State of Ohio signed amended substitute Senate bill 3 on July 6, 1999, requiring Ohio's electric industry to change from a monopoly environment to a competitive electric environment for generation services. The start date for competitive retail generation services was set for January 1, 2001. This new deregulation law allowed all Ohioans to choose the supplier of generation service, but the transmission and distribution would remain regulated. It also required electric utilities to unbundle the three main components (generation, transmission, and distribution) and make other changes designed to produce a competitive electric generation market. While deregulation was taking shape, the NASA Glenn Research Center electrical contract with FirstEnergy Corp. of Cleveland, Ohio, was to expire on September 7, 1999. Glenn strategically evaluated and incorporated the impacts of electric deregulation in the negotiations. Glenn and FirstEnergy spent over a year in negotiations until the Glenn utility team and the FirstEnergy negotiating team came to an agreement in the fall of 2000, and a new contract became effective on January 1, 2001.

Measurement of the Lorentz-FitzGerald body contraction

NASA Astrophysics Data System (ADS)

Rafelski, Johann

2018-02-01

A complete foundational discussion of acceleration in the context of Special Relativity (SR) is presented. Acceleration allows the measurement of a Lorentz-FitzGerald body contraction created. It is argued that in the back scattering of a probing laser beam from a relativistic flying electron cloud mirror generated by an ultra-intense laser pulse, a first measurement of a Lorentz-FitzGerald body contraction is feasible.

Level-2 Milestone 5213. CTS-1 Contract Award Completed

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

Leininger, Matt

2015-09-24

This report documents the fact that the first commodity technology (CT) system contract award, CTS-1, has been completed. The description of the milestone is: Based on Tri-Lab CTS-1 process and review, LLNL successfully awards the procurement for the next-generation Tri-Lab Linux CTS-1. The milestone completion criterion is: Signed contract. The milestone was completed on September 24th. 2015.

15 CFR Supplement No. 2 to Part 742 - Anti-Terrorism Controls: North Korea, Syria and Sudan Contract Sanctity Dates and Related Policies

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Robots capable of employing feedback information in real time processing to generate or modify programs...-uses in Syria will be considered on a case-by case basis. (A) Contract sanctity date for such robots... Supplement. (B) Contract sanctity date for all other such robots: August 28, 1991. (iii) Sudan. Applications...

15 CFR Supplement No. 2 to Part 742 - Anti-Terrorism Controls: North Korea, Syria and Sudan Contract Sanctity Dates and Related Policies

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Robots capable of employing feedback information in real time processing to generate or modify programs...-uses in Syria will be considered on a case-by case basis. (A) Contract sanctity date for such robots... Supplement. (B) Contract sanctity date for all other such robots: August 28, 1991. (iii) Sudan. Applications...

15 CFR Supplement No. 2 to Part 742 - Anti-Terrorism Controls: North Korea, Syria and Sudan Contract Sanctity Dates and Related Policies

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Robots capable of employing feedback information in real time processing to generate or modify programs...-uses in Syria will be considered on a case-by case basis. (A) Contract sanctity date for such robots... Supplement. (B) Contract sanctity date for all other such robots: August 28, 1991. (iii) Sudan. Applications...

15 CFR Supplement No. 2 to Part 742 - Anti-Terrorism Controls: North Korea, Syria and Sudan Contract Sanctity Dates and Related Policies

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Robots capable of employing feedback information in real time processing to generate or modify programs...-uses in Syria will be considered on a case-by case basis. (A) Contract sanctity date for such robots... Supplement. (B) Contract sanctity date for all other such robots: August 28, 1991. (iii) Sudan. Applications...

Sustained contraction and endothelial dysfunction induced by reactive oxygen species in porcine coronary artery.

PubMed

Ishihara, Yasuhiro; Sekine, Masaya; Hatano, Ai; Shimamoto, Norio

2008-09-01

A combination of purine and xanthine oxidase (XOD) dose-dependently elicited sustained contraction of porcine coronary arterial rings and resulted in increased concentrations of superoxide anions and hydrogen peroxide. These contractile responses appeared, with a delay, after the application of purine and XOD, used as a reactive oxygen species (ROS)-generating system. Coronary arteries precontracted with prostaglandin F(2alpha) failed to relax in response to substance P after exposing the arterial preparation to this ROS-generating system. The contractile response of the coronary artery to the ROS-generating system was almost completely inhibited by catalase (130 U/ml), and was partially inhibited by superoxide dismutase (60 U/ml), or mannitol (30 mM). A voltage-dependent L-type Ca(2+) channel antagonist, nicardipine, had no effect on contraction. Dysfunction of endothelial cells was completely prevented by catalase, but not by superoxide dismutase or mannitol. These results suggest that superoxide anions, hydrogen peroxide and hydroxyl radicals might be involved in eliciting sustained, delayed-onset coronary artery contraction, which is not related to L-type Ca(2+) channels. They also suggest that hydrogen peroxide might play a major role in endothelial dysfunction of the porcine coronary artery.

A STRICTLY CONTRACTIVE PEACEMAN-RACHFORD SPLITTING METHOD FOR CONVEX PROGRAMMING.

PubMed

Bingsheng, He; Liu, Han; Wang, Zhaoran; Yuan, Xiaoming

2014-07-01

In this paper, we focus on the application of the Peaceman-Rachford splitting method (PRSM) to a convex minimization model with linear constraints and a separable objective function. Compared to the Douglas-Rachford splitting method (DRSM), another splitting method from which the alternating direction method of multipliers originates, PRSM requires more restrictive assumptions to ensure its convergence, while it is always faster whenever it is convergent. We first illustrate that the reason for this difference is that the iterative sequence generated by DRSM is strictly contractive, while that generated by PRSM is only contractive with respect to the solution set of the model. With only the convexity assumption on the objective function of the model under consideration, the convergence of PRSM is not guaranteed. But for this case, we show that the first t iterations of PRSM still enable us to find an approximate solution with an accuracy of O (1/ t ). A worst-case O (1/ t ) convergence rate of PRSM in the ergodic sense is thus established under mild assumptions. After that, we suggest attaching an underdetermined relaxation factor with PRSM to guarantee the strict contraction of its iterative sequence and thus propose a strictly contractive PRSM. A worst-case O (1/ t ) convergence rate of this strictly contractive PRSM in a nonergodic sense is established. We show the numerical efficiency of the strictly contractive PRSM by some applications in statistical learning and image processing.

Functional difference in short- and long-latency interhemispheric inhibitions from active to resting hemisphere during a unilateral muscle contraction.

PubMed

Uehara, Kazumasa; Morishita, Takuya; Kubota, Shinji; Hirano, Masato; Funase, Kozo

2014-01-01

The aim of the present study was to investigate whether there is a functional difference in short-latency (SIHI) and long-latency (LIHI) interhemispheric inhibition from the active to the resting primary motor cortex (M1) with paired-pulse transcranial magnetic stimulation during a unilateral muscle contraction. In nine healthy right-handed participants, IHI was tested from the dominant to the nondominant M1 and vice versa under resting conditions or during performance of a sustained unilateral muscle contraction with the right or left first dorsal interosseous muscle at 10% and 30% maximum voluntary contraction. To obtain measurements of SIHI and LIHI, a conditioning stimulus (CS) was applied over the M1 contralateral to the muscle contraction, followed by a test stimulus over the M1 ipsilateral to the muscle contraction at short (10 ms) and long (40 ms) interstimulus intervals. We used four CS intensities to investigate SIHI and LIHI from the active to the resting M1 systematically. The amount of IHI during the unilateral muscle contractions showed a significant difference between SIHI and LIHI, but the amount of IHI during the resting condition did not. In particular, SIHI during the muscle contractions, but not LIHI, significantly increased with increase in CS intensity compared with the resting condition. Laterality of IHI was not detected in any of the experimental conditions. The present study provides novel evidence that a functional difference between SIHI and LIHI from the active to the resting M1 exists during unilateral muscle contractions.

Peroxide generation by p47phox-Src activation of Nox2 has a key role in protein kinase C-induced arterial smooth muscle contraction.

PubMed

Gupte, Sachin A; Kaminski, Pawel M; George, Shimran; Kouznestova, Lioubov; Olson, Susan C; Mathew, Rajamma; Hintze, Thomas H; Wolin, Michael S

2009-04-01

Protein kinase C (PKC) stimulation of NAD(P)H oxidases (Nox) is an important component of multiple vascular disease processes; however, the relationship between oxidase activation and the regulation of vascular smooth muscle contraction by PKC remains poorly understood. Therefore, we examined the signaling cascade of PKC-elicited Nox activation and the role of superoxide and hydrogen peroxide in mediating PKC-induced vascular contraction. Endothelium-denuded bovine coronary arteries showed a PKC-dependent basal production of lucigenin (5 muM)-detected Nox oxidase-derived superoxide, which was stimulated fourfold by PKC activation with 10 muM phorbol 12,13-dibutyrate (PDBu). PDBu appeared to increase superoxide generation by Nox2 through both p47(phox) and peroxide-dependent Src activation mechanisms based on the actions of inhibitors, properties of Src phosphorylation, and the loss of responses in aorta from mice deficient in Nox2 and p47(phox). The actions of inhibitors of contractile regulating mechanisms, scavengers of superoxide and peroxide, and responses in knockout mouse aortas suggest that a major component of the contraction elicited by PDBu appeared to be mediated through peroxide derived from Nox2 activation stimulating force generation through Rho kinase and calmodulin kinase-II mechanisms. Superoxide generated by PDBu also attenuated relaxation to nitroglycerin. Peroxide-derived from Nox2 activation by PKC appeared to be a major contributor to the thromboxane A(2) receptor agonist U46619 (100 nM)-elicited contraction of coronary arteries. Thus a p47(phox) and Src kinase activation of peroxide production by Nox2 appears to be an important contributor to vascular contractile mechanisms mediated through activation of PKC.

Selenide isotope generator for the Galileo mission. Reliability program plan

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

Not Available

1978-10-01

The reliability program plan for the Selenide Isotope Generator (SIG) program is presented. It delineates the specific tasks that will be accomplished by Teledyne Energy Systems and its suppliers during design, development, fabrication and test of deliverable Radioisotopic Thermoelectric Generators (RTG), Electrical Heated Thermoelectric Generators (ETG) and associated Ground Support Equipment (GSE). The Plan is formulated in general accordance with procedures specified in DOE Reliability Engineering Program Requirements Publication No. SNS-2, dated June 17, 1974. The Reliability Program Plan presented herein defines the total reliability effort without further reference to Government Specifications. The reliability tasks to be accomplished are delineatedmore » herein and become the basis for contract compliance to the extent specified in the SIG contract Statement of Work.« less

Systems Biology of Skeletal Muscle: Fiber Type as an Organizing Principle

PubMed Central

Greising, Sarah M; Gransee, Heather M; Mantilla, Carlos B; Sieck, Gary C

2012-01-01

Skeletal muscle force generation and contraction are fundamental to countless aspects of human life. The complexity of skeletal muscle physiology is simplified by fiber type classification where differences are observed from neuromuscular transmission to release of intracellular Ca2+ from the sarcoplasmic reticulum and the resulting recruitment and cycling of cross-bridges. This review uses fiber type classification as an organizing and simplifying principle to explore the complex interactions between the major proteins involved in muscle force generation and contraction. PMID:22811254

In vitro models of tail contraction and cytoplasmic streaming in amoeboid cells.

PubMed

Janson, L W; Taylor, D L

1993-10-01

We have developed a reconstituted gel-sol and contractile model system that mimics the structure and dynamics found at the ectoplasm/endoplasm interface in the tails of many amoeboid cells. We tested the role of gel-sol transformations of the actin-based cytoskeleton in the regulation of contraction and in the generation of endoplasm from ectoplasm. In a model system with fully phosphorylated myosin II, we demonstrated that either decreasing the actin filament length distribution or decreasing the extent of actin filament cross-linking initiated both a weakening of the gel strength and contraction. However, streaming of the solated gel components occurred only under conditions where the length distribution of actin was decreased, causing a self-destruct process of continued solation and contraction of the gel. These results offer significant support that gel strength plays an important role in the regulation of actin/myosin II-based contractions of the tail cortex in many amoeboid cells as defined by the solation-contraction coupling hypothesis (Taylor, D. L., and M. Fechheimer. 1982. Phil. Trans. Soc. Lond. B. 299:185-197). The competing processes of solation and contraction of the gel would appear to be mutually exclusive. However, it is the temporal-spatial balance of the rate and extent of two stages of solation, coupled to contraction, that can explain the conversion of gelled ectoplasm in the tail to a solated endoplasm within the same small volume, generation of a force for the retraction of tails, maintenance of cell polarity, and creation of a positive hydrostatic pressure to push against the newly formed endoplasm. The mechanism of solation-contraction of cortical cytoplasm may be a general component of the normal movement of a variety of amoeboid cells and may also be a component of other contractile events such as cytokinesis.

Dexmedetomidine-induced Contraction Involves Phosphorylation of Caldesmon by JNK in Endothelium-denuded Rat Aortas

PubMed Central

Baik, Jiseok; Ok, Seong-Ho; Cho, Hyunhoo; Yu, Jongsun; Kim, Woochan; Nam, In-Koo; Choi, Mun-Jeoung; Lee, Heon-Keun; Sohn, Ju-Tae

2014-01-01

Caldesmon, an inhibitory actin binding protein, binds to actin and inhibits actin-myosin interactions, whereas caldesmon phosphorylation reverses the inhibitory effect of caldesmon on actin-myosin interactions, potentially leading to enhanced contraction. The goal of this study was to investigate the cellular signaling pathway responsible for caldesmon phosphorylation, which is involved in the regulation of the contraction induced by dexmedetomidine (DMT), an alpha-2 adrenoceptor agonist, in endothelium-denuded rat aortas. SP600125 (a c-Jun NH2-terminal kinase [JNK] inhibitor) dose-response curves were generated in aortas that were pre-contracted with DMT or phorbol 12,13-dibutyrate (PDBu), a protein kinase C (PKC) activator. Dose-response curves to the PKC inhibitor chelerythrine were generated in rat aortas pre-contracted with DMT. The effects of SP600125 and rauwolscine (an alpha-2 adrenoceptor inhibitor) on DMT-induced caldesmon phosphorylation in rat aortic vascular smooth muscle cells (VSMCs) were investigated by western blot analysis. PDBu-induced caldesmon and DMT-induced PKC phosphorylation in rat aortic VSMCs was investigated by western blot analysis. The effects of GF109203X (a PKC inhibitor) on DMT- or PDBu-induced JNK phosphorylation in VSMCs were assessed. SP600125 resulted in the relaxation of aortas that were pre-contracted with DMT or PDBu, whereas rauwolscine attenuated DMT-induced contraction. Chelerythrine resulted in the vasodilation of aortas pre-contracted with DMT. SP600125 and rauwolscine inhibited DMT-induced caldesmon phosphorylation. Additionally, PDBu induced caldesmon phosphorylation, and GF109203X attenuated the JNK phosphorylation induced by DMT or PDBu. DMT induced PKC phosphorylation in rat aortic VSMCs. These results suggest that alpha-2 adrenoceptor-mediated, DMT-induced contraction involves caldesmon phosphorylation that is mediated by JNK phosphorylation by PKC. PMID:25332685

Observational study of contracts processing at 29 CTSA sites.

PubMed

Kiriakis, James; Gaich, Nicholas; Johnston, S Claiborne; Kitterman, Darlene; Rosenblum, Daniel; Salberg, Libby; Rifkind, Adam

2013-08-01

We measured contracts final negotiation (FN) and full execution (FE) times using shared definitions in a prospective observational study of management of contracts for clinical trials at 29 CTSA institutions. Median FN and FE times were reached in 39 and 91 days, respectively; mean times for FN and FE were 55 and 103 days, respectively. Individual site medians ranged from 3 to 116 days for FN and 34 to 197 days for FE. The use of master agreements (MAs) and previously negotiated terms (PNTs) was associated with significant reduction of FN times by a mean of 33 days (p < 0) and 22 days (p < 0.001), respectively. PNTs, but not MAs, were associated with significantly reduced FE time (22 days, p < 0.007). Gap analysis revealed a gap of 22 days between contracts negotiation and Institutional Review Board (IRB) review and intervals of 33 days (contracts) and 48 days (IRB review) during which the process steps were being conducted alone, suggesting a potential benefit with parallel processing. These baseline data support a plan to investigate root causes of prolonged study start-up time by examining causes of variation and outliers. © 2013 Wiley Periodicals, Inc.

Observational Study of Contracts Processing at 29 CTSA Sites

PubMed Central

Kiriakis, James; Gaich, Nicholas; Johnston, S. Claiborne; Kitterman, Darlene; Salberg, Libby; Rifkind, Adam

2013-01-01

Abstract We measured contracts final negotiation (FN) and full execution (FE) times using shared definitions in a prospective observational study of management of contracts for clinical trials at 29 CTSA institutions. Median FN and FE times were reached in 39 and 91 days, respectively; mean times for FN and FE were 55 and 103 days, respectively. Individual site medians ranged from 3 to 116 days for FN and 34 to 197 days for FE. The use of master agreements (MAs) and previously negotiated terms (PNTs) was associated with significant reduction of FN times by a mean of 33 days (p < 0) and 22 days (p < 0.001), respectively. PNTs, but not MAs, were associated with significantly reduced FE time (22 days, p < 0.007). Gap analysis revealed a gap of 22 days between contracts negotiation and Institutional Review Board (IRB) review and intervals of 33 days (contracts) and 48 days (IRB review) during which the process steps were being conducted alone, suggesting a potential benefit with parallel processing. These baseline data support a plan to investigate root causes of prolonged study start‐up time by examining causes of variation and outliers. PMID:23919362

Electrically contractile polymers augment right ventricular output in the heart.

PubMed

Ruhparwar, Arjang; Piontek, Patricia; Ungerer, Matthias; Ghodsizad, Ali; Partovi, Sasan; Foroughi, Javad; Szabo, Gabor; Farag, Mina; Karck, Matthias; Spinks, Geoffrey M; Kim, Seon Jeong

2014-12-01

Research into the development of artificial heart muscle has been limited to assembly of stem cell-derived cardiomyocytes seeded around a matrix, while nonbiological approaches to tissue engineering have rarely been explored. The aim of the study was to apply electrically contractile polymer-based actuators as cardiomyoplasty for positive inotropic support of the right ventricle. Complex trilayer polypyrrole (PPy) bending polymers for high-speed applications were generated. Bending motion occurred directly as a result of electrochemically driven charging and discharging of the PPy layers. In a rat model (n = 5), strips of polymers (3 × 20 mm) were attached and wrapped around the right ventricle (RV). RV pressure was continuously monitored invasively by direct RV cannulation. Electrical activation occurred simultaneously with either diastole (in order to evaluate the polymer's stand-alone contraction capacity; group 1) or systole (group 2). In group 1, the pressure generation capacity of the polymers was measured by determining the area under the pressure curve (area under curve, AUC). In group 2, the RV pressure AUC was measured in complexes directly preceding those with polymer contraction and compared to RV pressure complexes with simultaneous polymer contraction. In group 1, the AUC generated by polymer contraction was 2768 ± 875 U. In group 2, concomitant polymer contraction significantly increased AUC compared with complexes without polymer support (5987 ± 1334 U vs. 4318 ± 691 U, P ≤ 0.01). Electrically contractile polymers are able to significantly augment right ventricular contraction. This approach may open new perspectives for myocardial tissue engineering, possibly in combination with fetal or embryonic stem cell-derived cardiomyocytes. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Pigeons' Choices between Fixed-Interval and Random-Interval Schedules: Utility of Variability?

ERIC Educational Resources Information Center

Andrzejewski, Matthew E.; Cardinal, Claudia D.; Field, Douglas P.; Flannery, Barbara A.; Johnson, Michael; Bailey, Kathleen; Hineline, Philip N.

2005-01-01

Pigeons' choosing between fixed-interval and random-interval schedules of reinforcement was investigated in three experiments using a discrete-trial procedure. In all three experiments, the random-interval schedule was generated by sampling a probability distribution at an interval (and in multiples of the interval) equal to that of the…

A phenomenological model that predicts forces generated when electrical stimulation is superimposed on submaximal volitional contractions

PubMed Central

Perumal, Ramu; Wexler, Anthony S.; Kesar, Trisha M.; Jancosko, Angela; Laufer, Yocheved

2010-01-01

Superimposition of electrical stimulation during voluntary contractions is used to produce functional movements in individuals with central nervous system impairment, to evaluate the ability to activate a muscle, to characterize the nature of fatigue, and to improve muscle strength during postsurgical rehabilitation. Currently, the manner in which voluntary contractions and electrically elicited forces summate is not well understood. The objective of the present study is to develop a model that predicts the forces obtained when electrical stimulation is superimposed on a volitional contraction. Quadriceps femoris muscles of 12 able-bodied subjects were tested. Our results showed that the total force produced when electrical stimulation was superimposed during a volitional contraction could be modeled by the equation T = V + S[(MaxForce − V)/MaxForce]N, where T is the total force produced, V is the force in response to volitional contraction alone, S is the force response to the electrical stimulation alone, MaxForce is the maximum force-generating ability of the muscle, and N is a parameter that we posit depends on the differences in the motor unit recruitment order and firing rates between volitional and electrically elicited contractions. In addition, our results showed that the model predicted accurately (intraclass correlation coefficient ≥0.97) the total force in response to a wide range of stimulation intensities and frequencies superimposed on a wide range of volitional contraction levels. Thus the model will be helpful to clinicians and scientists to predict the amount of stimulation needed to produce the targeted force levels in individuals with partial paralysis. PMID:20299613

An IDEA for Short Term Outbreak Projection: Nearcasting Using the Basic Reproduction Number

PubMed Central

Fisman, David N.; Hauck, Tanya S.; Tuite, Ashleigh R.; Greer, Amy L.

2013-01-01

Background Communicable disease outbreaks of novel or existing pathogens threaten human health around the globe. It would be desirable to rapidly characterize such outbreaks and develop accurate projections of their duration and cumulative size even when limited preliminary data are available. Here we develop a mathematical model to aid public health authorities in tracking the expansion and contraction of outbreaks with explicit representation of factors (other than population immunity) that may slow epidemic growth. Methodology The Incidence Decay and Exponential Adjustment (IDEA) model is a parsimonious function that uses the basic reproduction number R0, along with a discounting factor to project the growth of outbreaks using only basic epidemiological information (e.g., daily incidence counts). Principal Findings Compared to simulated data, IDEA provides highly accurate estimates of total size and duration for a given outbreak when R0 is low or moderate, and also identifies turning points or new waves. When tested with an outbreak of pandemic influenza A (H1N1), the model generates estimated incidence at the i+1th serial interval using data from the ith serial interval within an average of 20% of actual incidence. Conclusions and Significance This model for communicable disease outbreaks provides rapid assessments of outbreak growth and public health interventions. Further evaluation in the context of real-world outbreaks will establish the utility of IDEA as a tool for front-line epidemiologists. PMID:24391797

An IDEA for short term outbreak projection: nearcasting using the basic reproduction number.

PubMed

Fisman, David N; Hauck, Tanya S; Tuite, Ashleigh R; Greer, Amy L

2013-01-01

Communicable disease outbreaks of novel or existing pathogens threaten human health around the globe. It would be desirable to rapidly characterize such outbreaks and develop accurate projections of their duration and cumulative size even when limited preliminary data are available. Here we develop a mathematical model to aid public health authorities in tracking the expansion and contraction of outbreaks with explicit representation of factors (other than population immunity) that may slow epidemic growth. The Incidence Decay and Exponential Adjustment (IDEA) model is a parsimonious function that uses the basic reproduction number R0, along with a discounting factor to project the growth of outbreaks using only basic epidemiological information (e.g., daily incidence counts). Compared to simulated data, IDEA provides highly accurate estimates of total size and duration for a given outbreak when R0 is low or moderate, and also identifies turning points or new waves. When tested with an outbreak of pandemic influenza A (H1N1), the model generates estimated incidence at the i+1(th) serial interval using data from the i(th) serial interval within an average of 20% of actual incidence. This model for communicable disease outbreaks provides rapid assessments of outbreak growth and public health interventions. Further evaluation in the context of real-world outbreaks will establish the utility of IDEA as a tool for front-line epidemiologists.

The work of titin protein folding as a major driver in muscle contraction

PubMed Central

Eckels, Edward C.; Tapia-Rojo, Rafael; Rivas-Pardo, Jamie Andrés; Fernández, Julio M.

2018-01-01

Single molecule atomic force microscopy and magnetic tweezers experiments have demonstrated that titin Ig domains are capable of folding against a pulling force, generating mechanical work which exceeds that produced by a myosin motor. We hypothesize that upon muscle activation, formation of actomyosin crossbridges reduces the force on titin causing entropic recoil of the titin polymer and triggering the folding of the titin Ig domains. In the physiological force range of 4–15 pN under which titin operates in muscle, the folding contraction of a single Ig domain can generate 200% of the work of entropic recoil, and occurs at forces which exceed the maximum stalling force of single myosin motors. Thus titin operates like a mechanical battery storing elastic energy efficiently by unfolding Ig domains, and delivering the charge back by folding when the motors are activated during a contraction. We advance the hypothesis that titin folding and myosin activation act as inextricable partners during muscle contraction. PMID:29433413

Generating variable and random schedules of reinforcement using Microsoft Excel macros.

PubMed

Bancroft, Stacie L; Bourret, Jason C

2008-01-01

Variable reinforcement schedules are used to arrange the availability of reinforcement following varying response ratios or intervals of time. Random reinforcement schedules are subtypes of variable reinforcement schedules that can be used to arrange the availability of reinforcement at a constant probability across number of responses or time. Generating schedule values for variable and random reinforcement schedules can be difficult. The present article describes the steps necessary to write macros in Microsoft Excel that will generate variable-ratio, variable-interval, variable-time, random-ratio, random-interval, and random-time reinforcement schedule values.

Cell-populated collagen lattice contraction model for the investigation of fibroblast collagen interactions.

PubMed

Ehrlich, H Paul; Moyer, Kurtis E

2013-01-01

The fibroblast-populated collagen lattice (FPCL) was intended to act as the dermal component for "skin-equivalent" or artificial skin developed for skin grafting burn patients. The "skin-equivalent" was clinically unsuccessful as a skin graft, but today it is successfully used as a dressing for the management of chronic wounds. The FPCL has, however, become an instrument for investigating cell-connective tissue interactions within a three-dimensional matrix. Through the capacity of cell compaction of collagen fibrils, the FPCL undergoes a reduction in volume referred to as lattice contraction. Lattice contraction proceeds by cell-generated forces that reduce the water mass between collagen fibers, generating a closer relationship between collagen fibers. The compaction of collagen fibers is responsible for the reduction in the FPCL volume. Cell-generated forces through the linkage of collagen fibers with fibroblast's cytoskeletal actin-rich microfilament structures are responsible for the completion of the collagen matrix compaction. The type of culture dish used to cast FPCL as well as the cell number will dictate the mechanism for compacting collagen matrices. Fibroblasts, at moderate density, cast as an FPCL within a petri dish and released from the surface of the dish soon after casting compact collagen fibers through cell tractional forces. Fibroblasts at moderate density cast as an FPCL within a tissue culture dish and not released for 4 days upon release show rapid lattice contraction through a mechanism of cell contraction forces. Fibroblasts at high density cast in an FPCL within a petri dish, released from the surface of the dish soon after casting, compact a collagen lattice very rapidly through forces related to cell elongation. The advantage of the FPCL contraction model is the study of cells in the three-dimensional environment, which is similar to the environment from which these cells were isolated. In this chapter methods are described for manufacturing collagen lattices, which assess the three forces involved in compacting and/or organizing collagen fibrils into thicker collagen fibers. The clinical relevance of the FPCL contraction model is related to advancing our understanding of wound contraction and scar contracture.

Effects of cross-bridge compliance on the force-velocity relationship and muscle power output

PubMed Central

Fenwick, Axel J.; Wood, Alexander M.

2017-01-01

Muscles produce force and power by utilizing chemical energy through ATP hydrolysis. During concentric contractions (shortening), muscles generate less force compared to isometric contractions, but consume greater amounts of energy as shortening velocity increases. Conversely, more force is generated and less energy is consumed during eccentric muscle contractions (lengthening). This relationship between force, energy use, and the velocity of contraction has important implications for understanding muscle efficiency, but the molecular mechanisms underlying this behavior remain poorly understood. Here we used spatially-explicit, multi-filament models of Ca2+-regulated force production within a half-sarcomere to simulate how force production, energy utilization, and the number of bound cross-bridges are affected by dynamic changes in sarcomere length. These computational simulations show that cross-bridge binding increased during slow-velocity concentric and eccentric contractions, compared to isometric contractions. Over the full ranges of velocities that we simulated, cross-bridge cycling and energy utilization (i.e. ATPase rates) increased during shortening, and decreased during lengthening. These findings are consistent with the Fenn effect, but arise from a complicated relationship between velocity-dependent cross-bridge recruitment and cross-bridge cycling kinetics. We also investigated how force production, power output, and energy utilization varied with cross-bridge and myofilament compliance, which is impossible to address under typical experimental conditions. These important simulations show that increasing cross-bridge compliance resulted in greater cross-bridge binding and ATPase activity, but less force was generated per cross-bridge and throughout the sarcomere. These data indicate that the efficiency of force production decreases in a velocity-dependent manner, and that this behavior is sensitive to cross-bridge compliance. In contrast, significant effects of myofilament compliance on force production were only observed during isometric contractions, suggesting that changes in myofilament compliance may not influence power output during non-isometric contractions as greatly as changes in cross-bridge compliance. These findings advance our understanding of how cross-bridge and myofilament properties underlie velocity-dependent changes in contractile efficiency during muscle movement. PMID:29284062

Effects of cross-bridge compliance on the force-velocity relationship and muscle power output.

PubMed

Fenwick, Axel J; Wood, Alexander M; Tanner, Bertrand C W

2017-01-01

Muscles produce force and power by utilizing chemical energy through ATP hydrolysis. During concentric contractions (shortening), muscles generate less force compared to isometric contractions, but consume greater amounts of energy as shortening velocity increases. Conversely, more force is generated and less energy is consumed during eccentric muscle contractions (lengthening). This relationship between force, energy use, and the velocity of contraction has important implications for understanding muscle efficiency, but the molecular mechanisms underlying this behavior remain poorly understood. Here we used spatially-explicit, multi-filament models of Ca2+-regulated force production within a half-sarcomere to simulate how force production, energy utilization, and the number of bound cross-bridges are affected by dynamic changes in sarcomere length. These computational simulations show that cross-bridge binding increased during slow-velocity concentric and eccentric contractions, compared to isometric contractions. Over the full ranges of velocities that we simulated, cross-bridge cycling and energy utilization (i.e. ATPase rates) increased during shortening, and decreased during lengthening. These findings are consistent with the Fenn effect, but arise from a complicated relationship between velocity-dependent cross-bridge recruitment and cross-bridge cycling kinetics. We also investigated how force production, power output, and energy utilization varied with cross-bridge and myofilament compliance, which is impossible to address under typical experimental conditions. These important simulations show that increasing cross-bridge compliance resulted in greater cross-bridge binding and ATPase activity, but less force was generated per cross-bridge and throughout the sarcomere. These data indicate that the efficiency of force production decreases in a velocity-dependent manner, and that this behavior is sensitive to cross-bridge compliance. In contrast, significant effects of myofilament compliance on force production were only observed during isometric contractions, suggesting that changes in myofilament compliance may not influence power output during non-isometric contractions as greatly as changes in cross-bridge compliance. These findings advance our understanding of how cross-bridge and myofilament properties underlie velocity-dependent changes in contractile efficiency during muscle movement.

A STRICTLY CONTRACTIVE PEACEMAN–RACHFORD SPLITTING METHOD FOR CONVEX PROGRAMMING

PubMed Central

BINGSHENG, HE; LIU, HAN; WANG, ZHAORAN; YUAN, XIAOMING

2014-01-01

In this paper, we focus on the application of the Peaceman–Rachford splitting method (PRSM) to a convex minimization model with linear constraints and a separable objective function. Compared to the Douglas–Rachford splitting method (DRSM), another splitting method from which the alternating direction method of multipliers originates, PRSM requires more restrictive assumptions to ensure its convergence, while it is always faster whenever it is convergent. We first illustrate that the reason for this difference is that the iterative sequence generated by DRSM is strictly contractive, while that generated by PRSM is only contractive with respect to the solution set of the model. With only the convexity assumption on the objective function of the model under consideration, the convergence of PRSM is not guaranteed. But for this case, we show that the first t iterations of PRSM still enable us to find an approximate solution with an accuracy of O(1/t). A worst-case O(1/t) convergence rate of PRSM in the ergodic sense is thus established under mild assumptions. After that, we suggest attaching an underdetermined relaxation factor with PRSM to guarantee the strict contraction of its iterative sequence and thus propose a strictly contractive PRSM. A worst-case O(1/t) convergence rate of this strictly contractive PRSM in a nonergodic sense is established. We show the numerical efficiency of the strictly contractive PRSM by some applications in statistical learning and image processing. PMID:25620862

H2O2 generated from mitochondrial electron transport chain in thoracic perivascular adipose tissue is crucial for modulation of vascular smooth muscle contraction.

PubMed

Costa, Rafael M; Filgueira, Fernando P; Tostes, Rita C; Carvalho, Maria Helena C; Akamine, Eliana H; Lobato, Nubia S

2016-09-01

The perivascular adipose tissue (PVAT) releases a variety of factors that affect vascular function. PVAT in the thoracic aorta shares characteristics with the brown adipose tissue, including a large amount of mitochondria. PVAT-derived factors influence both endothelial and smooth muscle function via several signaling mechanisms including the release/generation of reactive nitrogen and oxygen species. Considering the importance of reactive oxygen species (ROS) on vascular function and that mitochondria are an important source of ROS, we hypothesized that mitochondria-derived ROS in the PVAT modulates vascular reactivity. Vascular reactivity to norephinephrine (NE) was evaluated in thoracic aortic rings, with or without endothelium and/or PVAT, from male Wistar rats. Mitochondrial uncoupling, as well as hydrogen peroxide (H2O2) removal, increased the contraction in vessels surrounded by PVAT. PVAT stimulated with NE exhibited increased protein expression, determined by Western blot analysis, of manganese superoxide dismutase (Mn-SOD) and decreased protein expression of catalase. Ultimately, NE increased superoxide anion (O2(-)) generation in PVAT via increases in intracellular calcium. These results clearly demonstrate that mitochondrial electron transport chain (mETC) in PVAT contributes to modulation of aortic muscle contraction by generating higher amounts of O2(-) that is, in turn, dismutated to hydrogen peroxide, which then acts as a pivotal signaling molecule regulating vascular smooth muscle contraction. Copyright © 2015 Elsevier Inc. All rights reserved.

Long-term effects of substance P on the isolated guinea pig trachea.

PubMed

Schreiber, J; Slapke, J; Nieber, K; Oehme, P

1988-01-01

The undecapeptide substance P(SP) and its C-terminal sequence SP-5-11 induced a dose-dependent contraction of the isolated guinea pig trachea. SP-5-11 had a more potent bronchoconstrictive action than SP-1-11. The distal part of the isolated guinea pig trachea showed a greater reagibility to SP-5-11 than the proximal one. There was a continuous increase of the amplitude of the SP-1-11-induced contractions when the neuropeptide was added several times at one-hour intervals. Incubation with 10(-6) M SP-1-11 for 5 h reduced the reagibility of the isolated guinea pig trachea to acetylcholine.

History-dependence of muscle slack length following contraction and stretch in the human vastus lateralis.

PubMed

Stubbs, Peter W; Walsh, Lee D; D'Souza, Arkiev; Héroux, Martin E; Bolsterlee, Bart; Gandevia, Simon C; Herbert, Robert D

2018-06-01

In reduced muscle preparations, the slack length and passive stiffness of muscle fibres have been shown to be influenced by previous muscle contraction or stretch. In human muscles, such behaviours have been inferred from measures of muscle force, joint stiffness and reflex magnitudes and latencies. Using ultrasound imaging, we directly observed that isometric contraction of the vastus lateralis muscle at short lengths reduces the slack lengths of the muscle-tendon unit and muscle fascicles. The effect is apparent 60 s after the contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles. In reduced muscle preparations, stretch and muscle contraction change the properties of relaxed muscle fibres. In humans, effects of stretch and contraction on properties of relaxed muscles have been inferred from measurements of time taken to develop force, joint stiffness and reflex latencies. The current study used ultrasound imaging to directly observe the effects of stretch and contraction on muscle-tendon slack length and fascicle slack length of the human vastus lateralis muscle in vivo. The muscle was conditioned by (a) strong isometric contractions at long muscle-tendon lengths, (b) strong isometric contractions at short muscle-tendon lengths, (c) weak isometric contractions at long muscle-tendon lengths and (d) slow stretches. One minute after conditioning, ultrasound images were acquired from the relaxed muscle as it was slowly lengthened through its physiological range. The ultrasound image sequences were used to identify muscle-tendon slack angles and fascicle slack lengths. Contraction at short muscle-tendon lengths caused a mean 13.5 degree (95% CI 11.8-15.0 degree) shift in the muscle-tendon slack angle towards shorter muscle-tendon lengths, and a mean 5 mm (95% CI 2-8 mm) reduction in fascicle slack length, compared to the other conditions. A supplementary experiment showed the effect could be demonstrated if the muscle was conditioned by contraction at short lengths but not if the relaxed muscle was held at short lengths, confirming the role of muscle contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

Advanced Radioisotope Power Conversion Technology Research and Development

NASA Technical Reports Server (NTRS)

Wong, Wayne A.

2004-01-01

NASA's Radioisotope Power Conversion Technology program is developing next generation power conversion technologies that will enable future missions that have requirements that cannot be met by either the ubiquitous photovoltaic systems or by current Radioisotope Power System (RPS) technology. Performance goals of advanced radioisotope power systems include improvement over the state-of-practice General Purpose Heat Source/Radioisotope Thermoelectric Generator by providing significantly higher efficiency to reduce the number of radioisotope fuel modules, and increase specific power (watts/kilogram). Other Advanced RPS goals include safety, long-life, reliability, scalability, multi-mission capability, resistance to radiation, and minimal interference with the scientific payload. NASA has awarded ten contracts in the technology areas of Brayton, Stirling, Thermoelectric, and Thermophotovoltaic power conversion including five development contracts that deal with more mature technologies and five research contracts. The Advanced RPS Systems Assessment Team includes members from NASA GRC, JPL, DOE and Orbital Sciences whose function is to review the technologies being developed under the ten Radioisotope Power Conversion Technology contracts and assess their relevance to NASA's future missions. Presented is an overview of the ten radioisotope power conversion technology contracts and NASA's Advanced RPS Systems Assessment Team.

Pattern and forcing of Northern Hemisphere glacier variations during the last millennium

NASA Astrophysics Data System (ADS)

Porter, Stephen C.

1986-07-01

Time series depicting mountain glacier fluctuations in the Alps display generally similar patterns over the last two centuries, as do chronologies of glacier variations for the same interval from elsewhere in the Northern Hemisphere. Episodes of glacier advance consistently are associated with intervals of high average volcanic aerosol production, as inferred from acidity variations in a Greenland ice core. Advances occur whenever acidity levels rise sharply from background values to reach concentrations ≥1.2 μequiv H +/kg above background. A phase lag of about 10-15 yr, equivalent to reported response lags of Alpine glacier termini, separates the beginning of acidity increases from the beginning of subsequent ice advances. A similar relationship, but based on limited and less-reliable historical data and on lichenometric ages, is found for the preceding 2 centuries. Calibrated radiocarbon dates related to advances of non-calving and non-surging glaciers during the earlier part of the Little Ice Age display a comparable consistent pattern. An interval of reduced acidity values between about 1090 and 1230 A.D. correlates with a time of inferred glacier contraction during the Medieval Optimum. The observed close relation between Noothern Hemisphere glacier fluctuations and variations in Greenland ice-core acidity suggests that sulfur-rich aerosols generated by volcanic eruptions are a primary forcing mechanism of glacier fluctuations, and therefore of climate, on a decadal scale. The amount of surface cooling attributable to individual large eruptions or to episodes of eruptions is simlar to the probable average temperature reduction during culminations of Little Ice Age alacier advances (ca. 0.5°-1.2°C), as inferred from depression of equilibrium-line altitudes.

It Is Chloride Depletion Alkalosis, Not Contraction Alkalosis

PubMed Central

Galla, John H.

2012-01-01

Maintenance of metabolic alkalosis generated by chloride depletion is often attributed to volume contraction. In balance and clearance studies in rats and humans, we showed that chloride repletion in the face of persisting alkali loading, volume contraction, and potassium and sodium depletion completely corrects alkalosis by a renal mechanism. Nephron segment studies strongly suggest the corrective response is orchestrated in the collecting duct, which has several transporters integral to acid-base regulation, the most important of which is pendrin, a luminal Cl/HCO3− exchanger. Chloride depletion alkalosis should replace the notion of contraction alkalosis. PMID:22223876

The Reinforcing Event (RE) Menu

ERIC Educational Resources Information Center

Addison, Roger M.; Homme, Lloyd E.

1973-01-01

A motivational system, the Contingency Management System, uses contracts in which some amount of defined task behavior is demanded for some interval of reinforcing event. The Reinforcing Event Menu, a list of high probability reinforcing behaviors, is used in the system as a prompting device for the learner and as an aid for the administrator in…

78 FR 62771 - Self-Regulatory Organizations; BOX Options Exchange LLC; Notice of Filing and Immediate...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-22

... The Exchange proposes to amend interpretive material to Rule 5050 (Series of Options Contracts Open... Proposed Rule Change 1. Purpose The Exchange proposes to amend IM-5050-6 to Rule 5050 (Series of Options... the strike price interval setting parameters for their Short Term Option Series (``STOS'') Programs...

Gastrointestinal motility in relation to spontaneous meal occurrence in domestic fowls.

PubMed

Savory, C J

1987-10-01

The relationship between gastrointestinal (GI) motility and spontaneous feeding activity was investigated in five immature domestic hens, by recording simultaneously their feeding and contraction of the gizzard and duodenum. Different parameters of GI motility were interrelated, and gizzard contraction frequency (GCF) was used as an overall index of motility. Significant (P less than 0.05) changes in GCF relative to mealtimes varied between individual birds and between different meal length classes. The most consistent change was a rapid increase in GCF at the start of meals, followed by a decline which usually commenced before the end of long meals, but after the end of shorter ones. The increase in GCF commenced before the start of meals in one bird which had longer inter-meal intervals than the rest. There were no consistent changes in GCF at the ends of intervals or meals that might suggest a causal association between motility and hunger and satiety. It is suggested that the observed variation in GI motility may be accounted for mainly by variation in extrinsic stimulation from the vagus nerve.

Grandparental Exposures and Risk of Autism in the Third Generation

DTIC Science & Technology

2017-08-01

Generation PRINCIPAL INVESTIGATOR: Dr. Barbara A. Cohn CONTRACTING ORGANIZATION: Public Health Institute, Oakland, CA 94607...Fort Detrick, Maryland 21702-5012 DISTRIBUTION STATEMENT: Approved for Public Release

Arteriolar vasomotor control and contractile performance during fatiguing tetanic contractions in rat skeletal muscle: role of sympathetic system.

PubMed

Inagaki, Tadakatsu; Sonobe, Takashi; Poole, David C; Kano, Yutaka

2010-01-01

Using a fatiguing stimulation protocol designed specifically to enhance sympathetically-mediated vasoconstrictor tone, we explored the temporal profile of the evoked vasoconstrictor response, evaluated the presence of sympatholysis, and assessed the role of alpha1-adrenergic receptor-mediated vasoconstriction on muscle performance. Spinotrapezius muscles of Wistar rats were exteriorized and stimulated tetanically (100 Hz, 4-7 V, stimulus duration 700 ms) every 3 s for 2.5 min under control and prazosin (1 muM) superfused conditions. The extent and time course of diameter changes in arterioles (2 A) and venules (2 V) were determined after each of 10 discrete sets of muscle stimulation at 5-min intervals. A significant decrease of luminal diameter was observed in arterioles after tetanic contractions at 8-10 sets (8 sets: -34.4%, 9 sets: -39.4%, 10 sets: -38.6% vs pre-contraction at each set, p < 0.01). Prazosin significantly reduced but did not abolish the contraction-induced vasoconstriction. In both conditions, there was no reduction of venules diameter observed. Tetanic contractions force at the final 10th set was significantly decreased to 29.3 +/- 11.9% from pre-fatigue conditions, while tetanic contractions with prazosin force production was maintained at 70.4 +/- 14.2% at the 10th set. We conclude that in sequential bouts of contractions there was a progressively greater degree of arteriolar (but not venular) vasoconstriction which was attenuated substantially by prazosin.

Zero entropy continuous interval maps and MMLS-MMA property

NASA Astrophysics Data System (ADS)

Jiang, Yunping

2018-06-01

We prove that the flow generated by any continuous interval map with zero topological entropy is minimally mean-attractable and minimally mean-L-stable. One of the consequences is that any oscillating sequence is linearly disjoint from all flows generated by all continuous interval maps with zero topological entropy. In particular, the Möbius function is linearly disjoint from all flows generated by all continuous interval maps with zero topological entropy (Sarnak’s conjecture for continuous interval maps). Another consequence is a non-trivial example of a flow having discrete spectrum. We also define a log-uniform oscillating sequence and show a result in ergodic theory for comparison. This material is based upon work supported by the National Science Foundation. It is also partially supported by a collaboration grant from the Simons Foundation (grant number 523341) and PSC-CUNY awards and a grant from NSFC (grant number 11571122).

Marketing and commercialization of computational research services.

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

Toevs, J. W.

Physical and computational scientists and mathematicians in Russia's nuclear cities are turning their work toward generating profits from Western markets. Successful ventures require an understanding of the marketing of contract research as well as Western expectations regarding contract execution, quality, and performance. This paper will address fundamentals in business structure, marketing, and contract performance for organizations engaging in the marketing and commercialization of research services. Considerable emphasis will be placed on developing adequate communication within the organization.

Intrinsic rhythm and basic tonus in insect skeletal muscle.

PubMed

Hoyle, G

1978-04-01

The jumping muscle of orthopterous insects contains fibres that possess an intrinsic rhythm (IR) of slow contraction. The contributing fibres are generally synchronized, but as many as three or four pacemakers are present. The frequency, amplitude and duration of IR contractions fluctuate erratically over a 24 h period. Metathoracic DUM neurone bursts suppress IR for a few minutes. Other, unidentified dorsal neurones enhance its amplitude. In addition to IR, the extensor tibiae shows intrinsic basic tonus (BT). BT is relaxed for several s by low-frequency burst output from unidentified metathoracic dorsal neurones. DUM neurone bursts may enhance extensor BT, relax it, or leave it unaffected. The effects on IR of various regimes of activity in the slow extensor tibiae (SETi) and the common inhibitor (CI) axons were examined. CI affects IR when stimulated at frequencies above 2 Hz. It causes amplitude depression and reduced duration of individual IR contractions as well as increased frequency. At 30 Hz and above, CI completely suppresses IR. An enhanced IR contraction starts within a few milliseconds of the termination of a CI train. At low frequencies (below 10 Hz) SETi causes increased frequency and decreased amplitude of IR, with a depressed IR contraction following cessation of the SETi burst. At frequencies above 15 Hz the SETi-evoked contraction dominates tension development, though IR summates with it during the rising phase. In quiescent preparations not showing IR, SETi stimulation at 10 Hz often started up IR. Single SETi or FETi impulses can initiate an IR contraction, and cause altered phasing, with up to a quintupling of frequency. After a critical period has elapsed following the onset of an IR contraction, a single single impulse in any one of the three axons will terminate it abruptly. The early termination is followed by a reduced interval which is proportional to the reduced IR contraction time. The rhythm of accumulated readiness to go into an IR contraction is independent of the pacemaker rhythm that initiates the contraction.

A new technique for calculating individual dermal fibroblast contractile forces generated within collagen-GAG scaffolds.

PubMed

Harley, Brendan A; Freyman, Toby M; Wong, Matthew Q; Gibson, Lorna J

2007-10-15

Cell-mediated contraction plays a critical role in many physiological and pathological processes, notably organized contraction during wound healing. Implantation of an appropriately formulated (i.e., mean pore size, chemical composition, degradation rate) three-dimensional scaffold into an in vivo wound site effectively blocks the majority of organized wound contraction and results in induced regeneration rather than scar formation. Improved understanding of cell contraction within three-dimensional constructs therefore represents an important area of study in tissue engineering. Studies of cell contraction within three-dimensional constructs typically calculate an average contractile force from the gross deformation of a macroscopic substrate by a large cell population. In this study, cellular solids theory has been applied to conventional column buckling relationships to quantify the magnitude of individual cell contraction events within a three-dimensional, collagen-glycosaminoglycan scaffold. This new technique can be used for studying cell mechanics with a wide variety of porous scaffolds that resemble low-density, open-cell foams. It extends previous methods for analyzing cell buckling of two-dimensional substrates to three-dimensional constructs. From data available in the literature, the mean contractile force (Fc) generated by individual dermal fibroblasts within the collagen-glycosaminoglycan scaffold was calculated to range between 11 and 41 nN (Fc=26+/-13 nN, mean+/-SD), with an upper bound of cell contractility estimated at 450 nN.

ELECTRICAL LOAD ANTICIPATOR AND RECORDER

DOEpatents

Werme, J.E.

1961-09-01

A system is described in which an indication of the prevailing energy consumption in an electrical power metering system and a projected power demand for one demand in terval is provided at selected increments of time within the demand interval. Each watt-hour meter in the system is provided with an impulse generator that generates two impulses for each revolution of the meter disc. In each demand interval, for example, one half-hour, of the metering system, the total impulses received from all of the meters are continuously totaled for each 5-minute interval and multiplied by a number from 6 to 1 depending upon which 5- minute interval the impulses were received. This value is added to the total pulses received in the intervals preceding the current 5-minute interval within the half-hour demand interval tc thereby provide an indication of the projected power demand every 5 minutes in the demand interval.

Recommended Changes to Interval Management to Achieve Operational Implementation

NASA Technical Reports Server (NTRS)

Baxley, Brian; Swieringa, Kurt; Roper, Roy; Hubbs, Clay; Goess, Paul; Shay, Richard

2017-01-01

A 19-day flight test of an Interval Management (IM) avionics prototype was conducted in Washington State using three aircraft to precisely achieve and maintain a spacing interval behind the preceding aircraft. NASA contracted with Boeing, Honeywell, and United Airlines to build this prototype, and then worked closely with them, the FAA, and other industry partners to test this prototype in flight. Four different IM operation types were investigated during this test in the en route, arrival, and final approach phases of flight. Many of the IM operations met or exceeded the design goals established prior to the test. However, there were issues discovered throughout the flight test, including the rate and magnitude of IM commanded speed changes and the difference between expected and actual aircraft deceleration rates.

Motor training reduces surround inhibition in the motor cortex.

PubMed

Akkad, Haya; Di Stasio, Flavio; Tibold, Robert; Kassavetis, Panagiotis; Rothwell, John C; Edwards, Mark J

2016-06-01

Surround inhibition (SI) is thought to facilitate focal contraction of a hand muscle by keeping nearby muscles silent. Unexpectedly, SI is reduced in skilled pianists. We tested whether repeated practice of focal contraction in non-pianists could reduce SI. Motor-evoked potentials were elicited by transcranial magnetic stimulation in the relaxed abductor digiti minimi randomly at the onset and 5s after offset of a 2s focal contraction (10% maximum) of the first dorsal interosseous (FDI). Over 5 blocks of 40 trials participants obtained points for increasing contraction speed and stability in FDI. In a final block, the interval between contractions was varied randomly to increase attention to the task. Over the first 5 blocks, SI declined as performance (points scored) improved. In the final "attention" block SI increased towards baseline without affecting performance. Although SI may be useful during the early stages of learning, skilled focal finger movement does not require SI to prevent activity in non-involved muscles. This could be due to better targeting of the excitatory command to move. Results from the final block suggest that increased attention can re-engage SI when task parameters change. SI is not necessary for successful focal contraction, but may contribute during learning and during attention to task. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Geometric estimation of intestinal contraction for motion tracking of video capsule endoscope

NASA Astrophysics Data System (ADS)

Mi, Liang; Bao, Guanqun; Pahlavan, Kaveh

2014-03-01

Wireless video capsule endoscope (VCE) provides a noninvasive method to examine the entire gastrointestinal (GI) tract, especially small intestine, where other endoscopic instruments can barely reach. VCE is able to continuously provide clear pictures in short fixed intervals, and as such researchers have attempted to use image processing methods to track the video capsule in order to locate the abnormalities inside the GI tract. To correctly estimate the speed of the motion of the endoscope capsule, the radius of the intestinal track must be known a priori. Physiological factors such as intestinal contraction, however, dynamically change the radius of the small intestine, which could bring large errors in speed estimation. In this paper, we are aiming to estimate the radius of the contracted intestinal track. First a geometric model is presented for estimating the radius of small intestine based on the black hole on endoscopic images. To validate our proposed model, a 3-dimentional virtual testbed that emulates the intestinal contraction is then introduced in details. After measuring the size of the black holes on the test images, we used our model to esimate the radius of the contracted intestinal track. Comparision between analytical results and the emulation model parameters has verified that our proposed method could preciously estimate the radius of the contracted small intestine based on endoscopic images.

Evaluation of purinergic mechanism for the treatment of voiding dysfunction: a study in conscious spinal cord-injured rats.

PubMed

Lu, Shing-Hwa; Groat, William C de; Lin, Alex T L; Chen, Kuang-Kuo; Chang, Luke S

2007-10-01

To investigate the effect of a selective P2X(3-)P2X(2/3) purinergic receptor antagonist (a-317491) on detrusor hyperreflexia in conscious chronic spinal cord-injured female rats. Six chronic spinal cord-transected female Sprague-Dawley rats (290-336 g) were used in this study. Spinal transection at the T8-T9 segmental level was performed using aseptic techniques under halothane anesthesia. Fourteen to 16 weeks after spinal transection, A-317491, a selective P2X(3-)P2X(2/3) purinergic receptor antagonist, was administered intravenously in cystometry studies at increasing doses of 0.03, 0.1, 0.3, 1, 3, 10 and 30 micromol/kg at 40-50 minute intervals. Cystometrograms (CMGs) were performed before and after the administration of each dose of the drug. The continuous filling of CMGs revealed a large number of small-amplitude (> 8 cmH(2)O), non-voiding contractions (NVCs) (average, 9.7 per voiding cycle) preceding voiding contractions (mean amplitude, 31 cmH(2)O; duration, 2.5 minutes), which occurred at an interval of 539 seconds and at a pressure threshold of 5.7 cmH(2)O. When tested in a range of doses (0.03-30 micromol/kg, intravenous), A-317491 in doses between 1 and 30 micromol/kg significantly (p < 0.05) increased the interval between voids by 25%, reduced the number of NVCs by 42-62%, and increased the pressure threshold for voiding by 53-73%, but did not change the amplitude of the duration of the voiding contractions. The effects of the drug were apparent within 10 minutes following administration. These results indicate that purinergic mechanisms, presumably involving P2X(3) or P2X(2/3) receptors on bladder C-fiber afferent nerves, play an important role in the detrusor hyperreflexia that occurs after spinal cord injury in rats.

Defense Health Care: Acquisition Process for TRICARE’s Third Generation of Managed Care Support Contracts

DTIC Science & Technology

2014-03-01

nearly $92 billion by 2030.6 An advisory committee to the Secretary of Defense reported that rising health costs result from a number of factors that... report by a DOD advisory board.8 As of fiscal year 2012, the third generation of TRICARE’s MCSCs comprised DOD’s largest purchased care contracts. 9...North region, in 2017 in the South region, and in 2018 in the West region. The report raised concerns regarding the growth in DOD’s health care

48 CFR 1403.104-4 - Disclosure, protection, and marking of contractor bid or proposal information and source...

Code of Federal Regulations, 2010 CFR

2010-10-01

... a particular procurement: (1) Individuals who generate contract requirements, including program and... the contracting activity directly involved in the procurement; (4) Supervisors in the CO's chain of... ethics official and servicing Ethics Counselors; (17) Members of Congress and members of their staff...

Next Generation Enterprise Network: Navy Implementing Revised Approach, but Improvement Needed in Mitigating Risks

DTIC Science & Technology

2012-09-01

Hewlett Packard Enterprise Services) that ended in September 2010.2 To bridge the time between the end of the NMCI contract and the full transition to...some leasehold improvements; and moveable infrastructure associated with local network operations. Award contract for transport services and

Periodic organization of the contractile apparatus in smooth muscle revealed by the motion of dense bodies in single cells.

PubMed

Kargacin, G J; Cooke, P H; Abramson, S B; Fay, F S

1989-04-01

To study the organization of the contractile apparatus in smooth muscle and its behavior during shortening, the movement of dense bodies in contracting saponin skinned, isolated cells was analyzed from digital images collected at fixed time intervals. These cells were optically lucent so that punctate structures, identified immunocytochemically as dense bodies, were visible in them with the phase contrast microscope. Methods were adapted and developed to track the bodies and to study their relative motion. Analysis of their tracks or trajectories indicated that the bodies did not move passively as cells shortened and that nearby bodies often had similar patterns of motion. Analysis of the relative motion of the bodies indicated that some bodies were structurally linked to one another or constrained so that the distance between them remained relatively constant during contraction. Such bodies tended to fall into laterally oriented, semirigid groups found at approximately 6-microns intervals along the cell axis. Other dense bodies moved rapidly toward one another axially during contraction. Such bodies were often members of separate semirigid groups. This suggests that the semirigid groups of dense bodies in smooth muscle cells may provide a framework for the attachment of the contractile structures to the cytoskeleton and the cell surface and indicates that smooth muscle may be more well-ordered than previously thought. The methods described here for the analysis of the motion of intracellular structures should be directly applicable to the study of motion in other cell types.

Contracts in radiology practices: breaches and remedies.

PubMed

Muroff, Julie A; Muroff, Lawrence R

2004-08-01

Contracts between radiology groups and their physician members are often ambiguous. Key clauses may not be precise as to the intent of the contracting parties. For example, the requirements for a group member to achieve shareholder status may be discussed but not reduced to a written form. Other contract provisions, such as termination or noncompete clauses, may be subject to different interpretations. The ambiguities of these provisions often generate disparate expectations regarding the parties' obligations to one another. When this occurs, the results may vary from disappointment to litigation. This paper discusses the causes and consequences of common breaches of radiology contracts. The types of remedies that may be available to the parties of the contract are also enumerated, and case law is cited to illustrate the challenges that radiology groups and their members may encounter. Finally, alternative forms of dispute resolution are discussed.

Digital time delay

DOEpatents

Martin, A.D.

1986-05-09

Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay provides a first output signal at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits latch the high resolution data to form a first synchronizing data set. A selected time interval has been preset to internal counters and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses count down the counters to generate an internal pulse delayed by an internal which is functionally related to the preset time interval. A second LCD corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD to generate a second set of synchronizing data which is complementary with the first set of synchronizing data for presentation to logic circuits. The logic circuits further delay the internal output signal with the internal pulses. The final delayed output signal thereafter enables the output pulse generator to produce the desired output pulse at the preset time delay interval following input of the trigger pulse.

Generating Variable and Random Schedules of Reinforcement Using Microsoft Excel Macros

PubMed Central

Bancroft, Stacie L; Bourret, Jason C

2008-01-01

Variable reinforcement schedules are used to arrange the availability of reinforcement following varying response ratios or intervals of time. Random reinforcement schedules are subtypes of variable reinforcement schedules that can be used to arrange the availability of reinforcement at a constant probability across number of responses or time. Generating schedule values for variable and random reinforcement schedules can be difficult. The present article describes the steps necessary to write macros in Microsoft Excel that will generate variable-ratio, variable-interval, variable-time, random-ratio, random-interval, and random-time reinforcement schedule values. PMID:18595286

Acceleration of genetic gain in cattle by reduction of generation interval.

PubMed

Kasinathan, Poothappillai; Wei, Hong; Xiang, Tianhao; Molina, Jose A; Metzger, John; Broek, Diane; Kasinathan, Sivakanthan; Faber, David C; Allan, Mark F

2015-03-02

Genomic selection (GS) approaches, in combination with reproductive technologies, are revolutionizing the design and implementation of breeding programs in livestock species, particularly in cattle. GS leverages genomic readouts to provide estimates of breeding value early in the life of animals. However, the capacity of these approaches for improving genetic gain in breeding programs is limited by generation interval, the average age of an animal when replacement progeny are born. Here, we present a cost-effective approach that combines GS with reproductive technologies to reduce generation interval by rapidly producing high genetic merit calves.

Influence of different shortening velocities preceding stretch on human triceps surae moment generation in vivo.

PubMed

De Monte, Gianpiero; Arampatzis, Adamantios

2008-07-19

The purpose of this study was to examine the influence of different shortening velocities preceding the stretch on moment generation of the triceps surae muscles and architecture of the m. gastrocnemius medialis after shortening-stretch cycles of equal magnitude in vivo. Eleven male subjects (31.6+/-5.8 years, 178.4+/-7.3cm, 80.6+/-9.6kg) performed a series of electro-stimulated (85Hz) shortening-stretch plantar flexion contractions. The shortening-stretch cycles were performed at three constant angular velocities (25, 50, 100 degrees /s) in the plantar flexion direction (shortening) and at 50 degrees /s in the dorsiflexion direction (stretching). The resultant ankle joint moments were calculated through inverse dynamics. Pennation angle and fascicle length of the m. gastrocnemius medialis at rest and during contractions were measured using ultrasonography. The corresponding ankle moments, kinematics and changes in muscle architecture were analysed at seven time intervals. An analysis of variance for repeated measurements and post hoc test with Bonferroni correction was used to check the velocity-related effects on moment enhancement (alpha=0.05). The results show an increase in pennation angles and a decrease in fascicle lengths after the shortening-stretch cycle. The ankle joint moment ratio (post to pre) was higher (p<0.01) than 1.0 indicating a moment enhancement after the shortening-stretch cycle. The found ankle joint moment enhancement was 2-5% after the shortening-stretch cycle and was independed of the shortening velocity. Furthermore, the decrease in fascicle length after the shortening-stretch cycle indicates that the moment enhancement found in the present study is underestimated at least by 1-3%. Considering that the experiments have been done at the ascending limb of the force-length curve and that force enhancement is higher at the descending and the plateau region of the force-length curve, we conclude that the moment enhancement after shortening-stretch cycle can have important physiological affects while locomotion.

Studies of Cell-Mediated Immunity Against Immune Disorders Using Synthetic Peptides and Rotating Bioreactor System

NASA Technical Reports Server (NTRS)

Sastry, Jagannadha K.

1997-01-01

Our proposed experiments included: (1) immunzing mice with synthetic peptides; (2) preparing spleen and lymph node cells; (3) growing them under conventional conditions as well as in the rotatory vessel in appropriate medium reconstituting with synthetic peptides and/or cytokines as needed; and (4) comparing at regular time intervals the specific CTL activity as well as helper T-cell activity (in terms of both proliferative responses and cytokine production) using established procedures in my laboratory. We further proposed that once we demonstrated the merit of rotatory vessel technology to achieve desired results, these studies would be expanded to include immune cells from non-human primates (rhesus monkeys and chimpanzees) and also humans. We conducted a number of experiments to determine CTL induction by the synthetic peptides corresponding to antigenic proteins in HIV and HPV in different mouse strains that express MHC haplotypes H-2b or H-2d. We immunized mice with 100 ug of the synthetic peptide, suspended in sterile water, and emulsified in CFA (1:1). The immune lymph node cells obtained after 7 days were restimulated by culturing in T25 flask, HARV-10, or STLV-50, in the presence of the peptide at 20 ug/ml. The results from the 5'Cr-release assay consistently revealed complete abrogation of CTL activity of cells grown in the bioreactors (both HARV and STLV), while significant antigen-specific CTL activity was observed with cells cultured in tissue culture flasks. Thus, overall the data we generated in this study proved the usefulness of the NASA-developed developed technology for understanding the known immune deficiency during space travel. Additionally, this ex vivo microgravity technology since it mimics effectively the in vivo situation, it is also useful in understanding immune disorders in general. Thus, our proposed studies in TMC-NASA contract round II application benefit from data generated in this TMC-NASA contract round I study.

High resolution time interval meter

DOEpatents

Martin, A.D.

1986-05-09

Method and apparatus are provided for measuring the time interval between two events to a higher resolution than reliability available from conventional circuits and component. An internal clock pulse is provided at a frequency compatible with conventional component operating frequencies for reliable operation. Lumped constant delay circuits are provided for generating outputs at delay intervals corresponding to the desired high resolution. An initiation START pulse is input to generate first high resolution data. A termination STOP pulse is input to generate second high resolution data. Internal counters count at the low frequency internal clock pulse rate between the START and STOP pulses. The first and second high resolution data are logically combined to directly provide high resolution data to one counter and correct the count in the low resolution counter to obtain a high resolution time interval measurement.

What are the origins and relevance of spontaneous bladder contractions? ICI-RS 2017.

PubMed

Drake, Marcus J; Fry, Christopher H; Hashitani, Hikaru; Kirschner-Hermanns, Ruth; Rahnama'i, Mohammad S; Speich, John E; Tomoe, Hikaru; Kanai, Anthony J; McCloskey, Karen D

2018-01-23

Storage phase bladder activity is a counter-intuitive observation of spontaneous contractions. They are potentially an intrinsic feature of the smooth muscle, but interstitial cells in the mucosa and the detrusor itself, as well as other muscular elements in the mucosa may substantially influence them. They are identified in several models explaining lower urinary tract dysfunction. A consensus meeting at the International Consultation on Incontinence Research Society (ICI-RS) 2017 congress considered the origins and relevance of spontaneous bladder contractions by debating which cell type(s) modulate bladder spontaneous activity, whether the methodologies are sufficiently robust, and implications for healthy and abnormal lower urinary tract function. The identified research priorities reflect a wide range of unknown aspects. Cellular contributions to spontaneous contractions in detrusor smooth muscle are still uncertain. Accordingly, insight into the cellular physiology of the bladder wall, particularly smooth muscle cells, interstitial cells, and urothelium, remains important. Upstream influences, such as innervation, endocrine, and paracrine factors, are particularly important. The cellular interactions represent the key understanding to derive the integrative physiology of organ function, notably the nature of signalling between mucosa and detrusor layers. Indeed, it is still not clear to what extent spontaneous contractions generated in isolated preparations mirror their normal and pathological counterparts in the intact bladder. Improved models of how spontaneous contractions influence pressure generation and sensory nerve function are also needed. Deriving approaches to robust evaluation of spontaneous contractions and their influences for experimental and clinical use could yield considerable progress in functional urology. © 2018 Wiley Periodicals, Inc.

Communication between functional and denervated muscles using radiofrequency.

PubMed

Jacob, Doreen K; Stefko, Susan Tonya; Hackworth, Steven A; Lovell, Michael R; Mickle, Marlin H

2006-05-01

This article focuses on establishing communication between a functional muscle and a denervated muscle using a radiofrequency communications link. The ultimate objective of the project is to restore the eye blink in patients with facial nerve paralysis. Two sets of experiments were conducted using the gastrocnemius leg muscles of Sprague-Dawley rats. In the initial tests, varying magnitudes of voltages ranging from 0.85 to 2.5 V were applied directly to a denervated muscle to determine the voltage required to produce visible contraction. The second set of experiments was then conducted to determine the voltage output from an in vivo muscle contraction that could be sensed and used to coordinate a signal for actuation of a muscle in a separate limb. After designing the appropriate external communication circuitry, a third experiment was performed to verify that a signal between a functional and a denervated muscle can be generated and used as a stimulus. Voltages below 2 V at a 10-millisecond pulse width elicited a gentle, controlled contraction of the denervated muscle in vivo. It was also observed that with longer pulse widths, higher stimulation voltages were required to produce sufficient contractions. It is possible to detect contraction of a muscle, use this to generate a signal to an external base station, and subsequently cause a separate, denervated muscle to contract in response to the signal. This demonstration in vivo of a signaling system for pacing of electrical stimulation of 1 muscle to spontaneous contraction of another, separate muscle, using radiofrequency communication without direct connection, may be used in numerous ways to overcome nerve damage.

Microjet Generator for Highly Viscous Fluids

NASA Astrophysics Data System (ADS)

Onuki, Hajime; Oi, Yuto; Tagawa, Yoshiyuki

2018-01-01

This paper describes a simple system for generating a highly viscous microjet. The jet is produced inside a wettable thin tube partially submerged in a liquid. The gas-liquid interface inside the tube, which is initially concave, is kept much deeper than that outside the tube. An impulsive force applied at the bottom of a liquid container leads to significant acceleration of the liquid inside the tube followed by flow focusing due to the concave interface. The jet generation process can be divided into two parts that occur in different time scales, i.e., the impact interval [impact duration ≤O (10-4) s ] and the focusing interval [focusing duration ≫O (10-4) s ]. During the impact interval, the liquid accelerates suddenly due to the impact. During the focusing interval, the microjet emerges due to flow focusing. In order to explain the sudden acceleration inside the tube during the impact interval, we develop a physical model based on a pressure impulse approach. Numerical simulations confirm the proposed model, indicating that the basic mechanism of the acceleration of the liquid due to the impulsive force is elucidated. Remarkably, the viscous effect is negligible during the impact interval. In contrast, during the focusing interval, the viscosity plays an important role in the microjet generation. We experimentally and numerically investigate the velocity of microjets with various viscosities. We find that higher viscosities lead to reduction of the jet velocity, which can be described by using the Reynolds number (the ratio between the inertia force and the viscous force). This device may be a starting point for next-generation technologies, such as high-viscosity inkjet printers including bioprinters and needle-free injection devices for minimally invasive medical treatments.

Muscle activation and the isokinetic torque-velocity relationship of the human triceps surae.

PubMed

Harridge, S D; White, M J

1993-01-01

The influence of muscle activation and the time allowed for torque generation on the angle-specific torque-velocity relationship of the triceps surae was studied during plantar flexion using supramaximal electrical stimulation and a release technique on six male subjects [mean (SD) age 25 (4) years]. Torque-velocity data were obtained under different levels of constant muscle activation by varying the stimulus frequency and the time allowed for isometric torque generation prior to release and isokinetic shortening. To eliminate the effects of the frequency response on absolute torque the isokinetic data were normalized to the maximum isometric torque values at 0.44 rad. There were no significant differences in the normalized torques generated at any angular velocity using stimulus frequencies of 20, 50 or 80 Hz. When the muscle was stimulated at 50 Hz the torques obtained after a 400 ms and 1 s pre-release isometric contraction did not differ significantly. However, with no pre-release contraction significantly less torque was generated at all angular velocities beyond 1.05 rad.s-1 when compared with either the 200, 400 ms or 1 s condition. With a 200 ms pre-release contraction significantly less torque was generated at angular velocities beyond 1.05 rad.s-1 when compared with the 400 ms or 1 s conditions. It would seem that the major factor governing the shape of the torque-velocity curve at a constant level of muscle activation is the time allowed for torque generation.

Probing cooperative force generation in collective cancer invasion

NASA Astrophysics Data System (ADS)

Alobaidi, Amani A.; Xu, Yaopengxiao; Chen, Shaohua; Jiao, Yang; Sun, Bo

2017-08-01

Collective cellular dynamics in the three-dimensional extracellular matrix (ECM) plays a crucial role in many physiological processes such as cancer invasion. Both chemical and mechanical signaling support cell-cell communications on a variety of length scales, leading to collective migratory behaviors. Here we conduct experiments using 3D in vitro tumor models and develop a phenomenological model in order to probe the cooperativity of force generation in the collective invasion of breast cancer cells. In our model, cell-cell communication is characterized by a single parameter that quantifies the correlation length of cellular migration cycles. We devise a stochastic reconstruction method to generate realizations of cell colonies with specific contraction phase correlation functions and correlation length a. We find that as a increases, the characteristic size of regions containing cells with similar contraction phases grows. For small a values, the large fluctuations in individual cell contraction phases smooth out the temporal fluctuations in the time-dependent deformation field in the ECM. For large a values, the periodicity of an individual cell contraction cycle is clearly manifested in the temporal variation of the overall deformation field in the ECM. Through quantitative comparisons of the simulated and experimentally measured deformation fields, we find that the correlation length for collective force generation in the breast cancer diskoid in geometrically micropatterned ECM (DIGME) system is a≈ 25~μ \\text{m} , which is roughly twice the linear size of a single cell. One possible mechanism for this intermediate cell correlation length is the fiber-mediated stress propagation in the 3D ECM network in the DIGME system.

Renal myofibroblasts contract collagen I matrix lattices in vitro.

PubMed

Kelynack, K J; Hewitson, T D; Pedagogos, E; Nicholls, K M; Becker, G J

1999-01-01

Myofibroblasts, cells with both fibroblastic and smooth muscle cell features, have been implicated in renal scarring. In addition to synthetic properties, contractile features and integrin expression may allow myofibroblasts to rearrange and contract interstitial collagenous proteins. Myofibroblasts from normal rat kidneys were grown in cell-populated collagen lattices to measure cell generated contraction. Following detachment of cell populated collagen lattices, myofibroblasts progressively contracted collagen lattices, reducing lattice diameter by 42% at 24 h. Alignment of myofibroblasts, rearrangement of fibrils and beta(1) integrin expression were observed within lattices. We postulate that interstitial myofibroblasts contribute to renal scarring through manipulation of collagenous proteins. Copyright 1999 S. Karger AG, Basel

Stretch-induced contraction in pulmonary arteries.

PubMed

Kulik, T J; Evans, J N; Gamble, W J

1988-12-01

Stretch stimulates contraction of systemic blood vessels, but the response has not been described in pulmonary vessels. To determine whether pulmonary arteries contract when stretched, isolated cylindrical segments of pulmonary arteries were suspended between two parallel wires, stretched, and the active force was generated in response to stretch measured. Eighty-nine percent of segments from small (in situ diameter less than 1,000 microns) feline pulmonary arteries contracted when stretched, and in 65% of these the magnitude of stretch was related to the magnitude of contraction. Large (in situ diameter greater than or equal to 1,000 microns) feline pulmonary arteries did not contract with stretch. Multiple, rapidly repeated stretches resulted in a diminution of active force development. Stretch-induced contraction required external Ca2+ and was abolished by diltiazem (10 microns), but it was not affected by phenoxybenzamine, phentolamine, diethylcarbamazine, or mechanical removal of endothelium. Indomethacin blunted but did not abolish stretch-induced contraction, an effect that may have been nonspecific. This study suggests that stretch can act, probably directly, on smooth muscle in small feline pulmonary arteries to elicit contraction and that it may be a determinant of pulmonary vascular tone. In addition, feline pulmonary arteries are suitable for the in vitro study of stretch-induced contraction.

Differences in force normalising procedures during submaximal anisometric contractions.

PubMed

Škarabot, Jakob; Ansdell, Paul; Brownstein, Callum; Howatson, Glyn; Goodall, Stuart; Durbaba, Rade

2018-05-26

Eccentric contractions are thought to require a unique neural activation strategy. However, due to greater intrinsic force generating capacity of muscle fibres during eccentric contraction, the understanding of neural modulation of different contraction types during submaximal contractions may be impeded by the force normalisation procedure employed. In the present experiment, subjects performed maximal isometric dorsiflexion at shorter (80°), intermediate (90°) and longer (100°) muscle lengths, and maximal concentric and eccentric contractions. Thereafter, submaximal concentric and eccentric contractions were performed normalised to either isometric maximum at 90° (ISO), contraction type specific maximum (CTS) or muscle length specific maximum (MLS). When using ISO or MLS for normalisation, mean submaximal eccentric torque levels were significantly lower when compared to CTS normalisation (11 and 7% lower compared to CTS; p = 0.003 and p = 0.018 for ISO and MLS, respectively). These experimentally observed differences closely matched those expected from the predictive model. During submaximal concentric contraction, mean torque levels were similar between ISO and CTS normalisation with similar discrepancies noted in EMG activity. These findings suggest that normalising to ISO and MLS might not be accurate for assessment and prescription of submaximal eccentric contractions. Copyright © 2018 Elsevier Ltd. All rights reserved.

High resolution digital delay timer

DOEpatents

Martin, Albert D.

1988-01-01

Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay (20) provides a first output signal (24) at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits (26, 28) latch the high resolution data (24) to form a first synchronizing data set (60). A selected time interval has been preset to internal counters (142, 146, 154) and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses (32, 34) count down the counters to generate an internal pulse delayed by an interval which is functionally related to the preset time interval. A second LCD (184) corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD (74) to generate a second set of synchronizing data (76) which is complementary with the first set of synchronizing data (60) for presentation to logic circuits (64). The logic circuits (64) further delay the internal output signal (72) to obtain a proper phase relationship of an output signal (80) with the internal pulses (32, 34). The final delayed output signal (80) thereafter enables the output pulse generator (82) to produce the desired output pulse (84) at the preset time delay interval following input of the trigger pulse (10, 12).

Postextrasystolic potentiation and contractile reserve: requirements and restrictions.

PubMed

Lust, R M; Lutherer, L O; Gardner, M E; Cooper, M W

1982-12-01

These studies were conducted to examine the basic characteristics of postextrasystolic potentiation (PESP) and the relationship of loading effects to PESP. Measurements of left ventricular (LV) and aortic pressures, the rate of pressure rise, and echocardiographically determined LV dimensions were made in anesthetized open-chest dogs. The hearts were paced, and timed extrasystoles were introduced that were followed by postextrasystoles (PES). PES's were elicited after an interval equal to either a full compensatory pause or a time when the diastolic properties of the LV could not be distinguished from control (isolength). Potentiation of contraction for the PES's introduced after an isolength pause was dependent on both the heart rate and the extrasystolic interval, whereas the PES's that occurred after a full pause showed no dependence on either of these intervals. PESP elicited during the isolength period was not dependent on either preload and afterload. It is concluded that PESP depends on the combination of heart rate and extrasystolic and postextrasystolic intervals. Further, PESP may be inaccurate in assessing contractile reserve unless the heart rate and extrasystolic interval are known and the PES is introduced after an isolength pause.

Managed Utility Services Contracts | Climate Neutral Research Campuses |

Science.gov Websites

the energy cost savings generated by the project. Managed Utility Services Contracts In a Managed . The owner, in this case the research campus, bears no upfront cost through this agreement, pays the revenue to capital cost repayment and maintenance costs. In addition to removing the burden of an upfront

43 CFR 3287.2 - When may BLM grant a suspension of unit obligations?

Code of Federal Regulations, 2012 CFR

2012-10-01

..., the unit operator is prevented from complying with such obligations, in whole or in part, by: (1) Acts... operator's inability to obtain an electrical sales contract, or when poor economics affect the electrical generation market, limiting the opportunity to obtain a viable sales contract. BLM may grant a suspension of...

43 CFR 3287.2 - When may BLM grant a suspension of unit obligations?

Code of Federal Regulations, 2014 CFR

2014-10-01

..., the unit operator is prevented from complying with such obligations, in whole or in part, by: (1) Acts... operator's inability to obtain an electrical sales contract, or when poor economics affect the electrical generation market, limiting the opportunity to obtain a viable sales contract. BLM may grant a suspension of...

43 CFR 3287.2 - When may BLM grant a suspension of unit obligations?

Code of Federal Regulations, 2013 CFR

2013-10-01

..., the unit operator is prevented from complying with such obligations, in whole or in part, by: (1) Acts... operator's inability to obtain an electrical sales contract, or when poor economics affect the electrical generation market, limiting the opportunity to obtain a viable sales contract. BLM may grant a suspension of...

48 CFR 227.7104 - Contracts under the Small Business Innovation Research (SBIR) Program.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Data and Computer Software—Small Business Innovation Research (SBIR) Program, when technical data or computer software will be generated during performance of contracts under the SBIR program. (b) Under the clause at 252.227-7018, the Government obtains SBIR data rights in technical data and computer software...

48 CFR 227.7104 - Contracts under the Small Business Innovation Research (SBIR) Program.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Data and Computer Software—Small Business Innovation Research (SBIR) Program, when technical data or computer software will be generated during performance of contracts under the SBIR program. (b) Under the clause at 252.227-7018, the Government obtains SBIR data rights in technical data and computer software...

13 CFR 127.604 - How will SBA process an EDWOSB or WOSB status protest?

Code of Federal Regulations, 2011 CFR

2011-01-01

... award the contract or begin performance after receipt of a protest if the contracting officer determines... to begin performance. (2) Where award was made and performance commenced before receipt of a negative... must update the Federal Procurement Data System-Next Generation (FPDS-NG) and other databases from the...

Contrasting Scientific Knowledge with Knowledge from the Lifeworld: The Dialogic Inclusion Contract

ERIC Educational Resources Information Center

Padros, Maria; Garcia, Rocio; de Mello, Roseli; Molina, Silvia

2011-01-01

The Dialogic Inclusion Contract (DIC) consists in an agreement between the scientific community and social agents to define successful actions aimed at overcoming social exclusion in highly underprivileged areas. Taking the case of a Spanish neighborhood that is generating important transformations, this article explores the process of defining…

Retest reliability of force-time variables of neck muscles under isometric conditions.

PubMed

Almosnino, Sivan; Pelland, Lucie; Stevenson, Joan M

2010-01-01

Proper conditioning of the neck muscles may play a role in reducing the risk of neck injury and, possibly, concussions in contact sports. However, the ability to reliably measure the force-time-based variables that might be relevant for this purpose has not been addressed. To assess the between-days reliability of discrete force-time-based variables of neck muscles during maximal voluntary isometric contractions in 5 directions. Cohort study. University research center. Twenty-six highly physically active men (age  =  21.6 ± 2.1 years, height  =  1.85 ± 0.09 m, mass  =  81.6 ± 9.9 kg, head circumference  =  0.58 ± 0.01 m, neck circumference  =  0.39 ± 0.02 m). We used a custom-built testing apparatus to measure maximal voluntary isometric contractions of the neck muscles in 5 directions (extension, flexion, protraction, left lateral bending, and right lateral bending) on 2 separate occasions separated by 7 to 8 days. Variables measured were peak force (PF), rate of force development (RFD), and time to 50% of PF (T(50)PF). Reliability indices calculated for each variable comprised the difference in scores between the testing sessions, with corresponding 95% confidence intervals, the coefficient of variation of the typical error of measurement (CV(TE)), and intraclass correlation coefficients (ICC [3,3]). No evidence of systematic bias was detected for the dependent measures across any movement direction; retest differences in measurements were between 1.8% and 2.7%, with corresponding 95% confidence interval ranges of less than 10% and overlapping zero. The CV(TE) was lowest for PF (range, 2.4%-6.3%) across all testing directions, followed by RFD (range, 4.8%-9.0%) and T(50)PF (range, 7.1%-9.3%). The ICC score range for all dependent measures was 0.90 to 0.99. Discrete variables representative of the force-generating capacity of neck muscles under isometric conditions can be measured with an acceptable degree of reliability. This finding has possible applications for investigating the role of neck muscle strength-training programs in reducing the risk of injuries in sport settings.

NASA Project Develops Next-Generation Low-Emissions Combustor Technologies

NASA Technical Reports Server (NTRS)

Lee, Chi-Ming; Chang, Clarence T.; Herbon, John T.; Kramer, Stephen K.

2013-01-01

NASA's Environmentally Responsible Aviation (ERA) Project is working with industry to develop the fuel flexible combustor technologies for a new generation of low-emissions engine targeted for the 2020 timeframe. These new combustors will reduce nitrogen oxide (NOx) emissions to half of current state-of-the-art (SOA) combustors, while simultaneously reducing noise and fuel burn. The purpose of the low NOx fuel-flexible combustor research is to advance the Technology Readiness Level (TRL) and Integration Readiness Level (IRL) of a low NOx, fuel flexible combustor to the point where it can be integrated in the next generation of aircraft. To reduce project risk and optimize research benefit NASA chose to found two Phase 1 contracts. The first Phase 1 contracts went to engine manufactures and were awarded to: General Electric Company, and Pratt & Whitney Company. The second Phase 1 contracts went to fuel injector manufactures Goodrich Corporation, Parker Hannifin Corporation, and Woodward Fuel System Technology. In 2012, two sector combustors were tested at NASA's ASCR. The results indicated 75% NOx emission reduction below the 2004 CAEP/6 regulation level.

What evidence implicates airway smooth muscle in the cause of BHR?

PubMed

Dulin, Nickolai O; Fernandes, Darren J; Dowell, Maria; Bellam, Shashi; McConville, John; Lakser, Oren; Mitchell, Richard; Camoretti-Mercado, Blanca; Kogut, Paul; Solway, Julian

2003-02-01

Bronchial hyperresponsiveness (BHR), the occurrence of excessive bronchoconstriction in response to relatively small constrictor stimuli, is a cardinal feature of asthma. Here, we consider the role that airway smooth muscle might play in the generation of BHR. The weight of evidence suggests that smooth muscle isolated from asthmatic tissues exhibits normal sensitivity to constrictor agonists when studied during isometric contraction, but the increased muscle mass within asthmatic airways might generate more total force than the lesser amount of muscle found in normal bronchi. Another salient difference between asthmatic and normal individuals lies in the effect of deep inhalation (DI) on bronchoconstriction. DI often substantially reverses induced bronchoconstriction in normals, while it often has much less effect on spontaneous or induced bronchoconstriction in asthmatics. It has been proposed that abnormal dynamic aspects of airway smooth muscle contraction velocity of contraction or plasticity- elasticity balance might underlie the abnormal DI response in asthma. We suggest a speculative model in which abnormally long actin filaments might account for abnormally increased elasticity of contracted airway smooth muscle.

Potentiation and recovery following low- and high-speed isokinetic contractions in boys.

PubMed

Chaouachi, Anis; Haddad, Monoem; Castagna, Carlo; Wong, Del P; Kaouech, Fathi; Chamari, Karim; Behm, David G

2011-02-01

The objective of this study was to examine the response and recovery to a single set of maximal, low and high angular velocity isokinetic leg extension-flexion contractions with boys. Sixteen boys (11-14 yrs) performed 10 isokinetic contractions at 60°.s-1 (Isok60) and 300°.s-1 (Isok300). Three contractions at both velocities, blood lactate and ratings of perceived exertion were monitored pretest and at 2, 3, 4, and 5 min of recovery (RI). Participants were tested in a random counterbalanced order for each velocity and recovery period. Only a single contraction velocity (300°.s-1 or 60°.s-1) was tested during recovery at each session to remove confounding influences between the recovery intervals. Recovery results showed no change in quadriceps' power at 300°.s-1, quadriceps' power, work and torque at 60°.s-1 and hamstrings' power and work with 60°.s-1. There was an increase during the 2 min RI in hamstrings' power, work and torque and quadriceps' torque with isokinetic contractions at 300°.s-1 suggesting a potentiating effect. Performance impairments during recovery occurred for the hamstrings torque at 60°.s-1 and quadriceps work with 300°.s-1. In conclusion, 10 repetitions of either low or high velocity isokinetic contractions (Isok60 or Isok300) resulted in full recovery or potentiation of most measures within 2 min in boys. The potentiation effect predominantly occurred following the hamstrings Isok300 which might be attributed to a greater agonist-antagonist torque balance and less metabolic stress associated with the shorter duration higher velocity contractions.

Does the Length of Elbow Flexors and Visual Feedback Have Effect on Accuracy of Isometric Muscle Contraction in Men after Stroke?

PubMed Central

Juodzbaliene, Vilma; Darbutas, Tomas; Skurvydas, Albertas

2016-01-01

The aim of the study was to determine the effect of different muscle length and visual feedback information (VFI) on accuracy of isometric contraction of elbow flexors in men after an ischemic stroke (IS). Materials and Methods. Maximum voluntary muscle contraction force (MVMCF) and accurate determinate muscle force (20% of MVMCF) developed during an isometric contraction of elbow flexors in 90° and 60° of elbow flexion were measured by an isokinetic dynamometer in healthy subjects (MH, n = 20) and subjects after an IS during their postrehabilitation period (MS, n = 20). Results. In order to evaluate the accuracy of the isometric contraction of the elbow flexors absolute errors were calculated. The absolute errors provided information about the difference between determinate and achieved muscle force. Conclusions. There is a tendency that greater absolute errors generating determinate force are made by MH and MS subjects in case of a greater elbow flexors length despite presence of VFI. Absolute errors also increase in both groups in case of a greater elbow flexors length without VFI. MS subjects make greater absolute errors generating determinate force without VFI in comparison with MH in shorter elbow flexors length. PMID:27042670

Method and apparatus for granting processors access to a resource

DOEpatents

Blumrich, Matthias A.; Salapura, Valentina

2010-03-16

An apparatus and method for granting one or more requesting entities access to a resource in a predetermined time interval. The apparatus includes a first circuit receiving one or more request signals, and implementing logic for assigning a priority to the one or more request signals, and, generating a set of first_request signals based on the priorities assigned. One or more priority select circuits for receiving the set of first_request signals and generating corresponding one or more fixed grant signals representing one or more highest priority request signals when asserted during the predetermined time interval. A second circuit device receives the one or more fixed grant signals generates one or more grant signals associated with one or more highest priority request signals assigned, the grant signals for enabling one or more respective requesting entities access to the resource in the predetermined time interval, wherein the priority assigned to the one or more request signals changes each successive predetermined time interval. In one embodiment, the assigned priority is based on a numerical pattern, the first circuit changing the numerical pattern with respect to the first_request signals generated at each successive predetermined time interval.

Identifying Psychological Contract Breaches to Guide Improvements in Faculty Recruitment, Retention, and Development

PubMed Central

Desselle, Shane P.; Draugalis, JoLaine R.; Spies, Alan R.; Davis, Tamra S.; Bolino, Mark

2012-01-01

Objective. To identify pharmacy faculty members’ perceptions of psychological contract breaches that can be used to guide improvements in faculty recruitment, retention, and development. Methods. A list of psychological contract breaches was developed using a Delphi procedure involving a panel of experts assembled through purposive sampling. The Delphi consisted of 4 rounds, the first of which elicited examples of psychological contract breaches in an open-ended format. The ensuing 3 rounds consisting of a survey and anonymous feedback on aggregated group responses. Results. Usable responses were obtained from 11 of 12 faculty members who completed the Delphi procedure. The final list of psychological contract breaches included 27 items, after modifications based on participant feedback in subsequent rounds. Conclusion. The psychological contract breach items generated in this study provide guidance for colleges and schools of pharmacy regarding important aspects of faculty recruitment, retention, and development. PMID:22919084

Identifying psychological contract breaches to guide improvements in faculty recruitment, retention, and development.

PubMed

Peirce, Gretchen L; Desselle, Shane P; Draugalis, JoLaine R; Spies, Alan R; Davis, Tamra S; Bolino, Mark

2012-08-10

To identify pharmacy faculty members' perceptions of psychological contract breaches that can be used to guide improvements in faculty recruitment, retention, and development. A list of psychological contract breaches was developed using a Delphi procedure involving a panel of experts assembled through purposive sampling. The Delphi consisted of 4 rounds, the first of which elicited examples of psychological contract breaches in an open-ended format. The ensuing 3 rounds consisting of a survey and anonymous feedback on aggregated group responses. Usable responses were obtained from 11 of 12 faculty members who completed the Delphi procedure. The final list of psychological contract breaches included 27 items, after modifications based on participant feedback in subsequent rounds. The psychological contract breach items generated in this study provide guidance for colleges and schools of pharmacy regarding important aspects of faculty recruitment, retention, and development.

Ruminal motility of stocker cattle grazed on winter wheat pasture.

PubMed

Horn, G W; Frost, D F

1982-10-01

A 2-yr study was conducted to determine whether bloat of stocker cattle grazing winter wheat pasture is a primary bloat or a secondary bloat as a result of reduced ruminal motility. Amplitude (mm Hg) and frequency of ruminal contractions (contractions/min) of steers were measured before and after the steers were placed on wheat pasture, and at about weekly intervals during the pasture grazing periods. Implantable pressure transducers and water-filled balloon cannulas were used to measure ruminal motility. During the first year, amplitude of contractions increased (P less than .005) during grazing of wheat pasture (i.e., 20.5 vs 6.7 and 21.6 vs 12.9, respectively, for steers with implanted pressure transducers and water-filled balloon cannulas). Frequency of ruminal contractions of steers on wheat pasture was not decreased (P greater than .05). In the second year, amplitudes of ruminal contractions of steers on wheat pasture ranged from 11.0 to 33.5, and were either similar or greater (P less than .05) than the mean for the pre- and post-wheat pasture period (16.5). Frequencies of ruminal contractions that ranged from 1.66 to 1.80 were observed on four dates during the pasture grazing period, and were decreased (P less than .05) as compared with the mean for the pre- and post-wheat pasture period (2.43). However, the reduced frequencies were not accompanied by reduced (P greater than .05) amplitude x frequency of contractions. The data indicate that ruminal motility is not decreased in stocker cattle grazing winter wheat pasture.

Intraarticular arthrofibrosis of the knee alters patellofemoral contact biomechanics.

PubMed

Mikula, Jacob D; Slette, Erik L; Dahl, Kimi D; Montgomery, Scott R; Dornan, Grant J; O'Brien, Luke; Turnbull, Travis Lee; Hackett, Thomas R

2017-12-19

Arthrofibrosis in the suprapatellar pouch and anterior interval can develop after knee injury or surgery, resulting in anterior knee pain. These adhesions have not been biomechanically characterized. The biomechanical effects of adhesions in the suprapatellar pouch and anterior interval during simulated quadriceps muscle contraction from 0 to 90° of knee flexion were assessed. Adhesions of the suprapatellar pouch and anterior interval were hypothesized to alter the patellofemoral contact biomechanics and increase the patellofemoral contact force compared to no adhesions. Across all flexion angles, suprapatellar adhesions increased the patellofemoral contact force compared to no adhesions by a mean of 80 N. Similarly, anterior interval adhesions increased the contact force by a mean of 36 N. Combined suprapatellar and anterior interval adhesions increased the mean patellofemoral contact force by 120 N. Suprapatellar adhesions resulted in a proximally translated patella from 0 to 60°, and anterior interval adhesions resulted in a distally translated patella at all flexion angles other than 15° (p < 0.05). The most important finding in this study was that patellofemoral contact forces were significantly increased by simulated adhesions in the suprapatellar pouch and anterior interval. Anterior knee pain and osteoarthritis may result from an increase in patellofemoral contact force due to patellar and quadriceps tendon adhesions. For these patients, arthroscopic lysis of adhesions may be beneficial.

An Analysis of the Speed Commands from an Interval Management Algorithm during the ATD-1 Flight Test

NASA Technical Reports Server (NTRS)

Watters, Christine; Wilson, Sara R.; Swieringa, Kurt A.

2017-01-01

NASA's first Air Traffic Management Technology Demonstration (ATD-1) successfully completed a nineteen-day flight test under a NASA contract with Boeing, with Honeywell and United Airlines as sub-contractors. An Interval Management (IM) avionics prototype was built based on international IM standards, integrated into two test aircraft, and then flown in real-world conditions to determine if the goals of improving aircraft efficiency and airport throughput during high-density arrival operations could be met. This paper describes the speed behavior of the IM avionics prototype, focusing on the speed command rate and the number of speed increases.

Torque, Current, and Discomfort During 3 Types of Neuromuscular Electrical Stimulation of Tibialis Anterior.

PubMed

Wiest, Matheus J; Bergquist, Austin J; Collins, David F

2017-08-01

The benefits of neuromuscular electrical stimulation (NMES) for rehabilitation depend on the capacity to generate functionally relevant torque with minimal fatigability and discomfort. Traditionally, NMES is delivered either over a muscle belly (mNMES) or a nerve trunk (nNMES). Recently, a technique that minimizes contraction fatigability by alternating pulses between the mNMES and nNMES sites, termed "interleaved" NMES (iNMES), was developed. However, discomfort and the ability to generate large torque during iNMES have not been explored adequately. The study objective was to compare discomfort and maximal torque between mNMES, nNMES, and iNMES. Stimulation trains (12 pulses at 40 Hz) were delivered to produce dorsiflexion torque using mNMES, nNMES, and iNMES. Discomfort was assessed using a visual analogue scale for contractions that generated 5-30% of a maximal voluntary isometric contraction (MVIC), and for the maximal tolerable torque. Discomfort scores were not different between NMES types when torque was ≤20% MVIC. At 30% MVIC, mNMES produced more discomfort than nNMES and iNMES. nNMES produced the most torque (65% MVIC), followed by iNMES (49% MVIC) and mNMES (33% MVIC); in these trials, mNMES produced more discomfort than nNMES, but not iNMES. The present results may be limited to individuals with no history of neuromusculoskeletal impairment. In terms of discomfort, there were no differences between mNMES, nNMES, or iNMES for contractions between 5-20% MVIC. However, mNMES produced more discomfort than nNMES and iNMES for contractions of 30% MVIC, while for larger contractions, mNMES only produced more discomfort than nNMES. The advantages and disadvantages of each NMES type should be considered prior to implementation in rehabilitation programs. © 2017 American Physical Therapy Association

Reformation of PURPA contracts: Strategies for success in power marketing

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

Scalzo, P.J.

With the passage of the Energy Policy Act of 1992, real competition entered into the world of electric utilities. A slide presentations is given on reformation of Public Utility Regulatory Policies Act (PURPA) Contracts for success in power marketing strategies. Two ways to compete: Be the least cost provider or add value and `sell hard`. The PURPA vision was to increase efficiency in power generation, utilize renewable or waste fuels, and bolster the independent producers. Cogenerators and small power producers qualified. Utility planners predicted, avoided cost, utility loads, and oil and gas prices to increase. However, avoided costs, and oilmore » and gase prices declined. Two scenarios are discussed for contract reformation: Contract buyouts, and renegotiation of contracts. Options for for dealing with existing fuel agreements are presented.« less

Generator Set Environmental and Stability Testing

DTIC Science & Technology

2015-03-01

UNCLASSIFIED GENERATOR SET ENVIRONMENTAL AND STABILITY TESTING INTERIM REPORT TFLRF No. 460 by Gregory A. Hansen Edwin A...it to the originator. UNCLASSIFIED GENERATOR SET ENVIRONMENTAL AND STABILITY TESTING INTERIM REPORT TFLRF No. 460 by...TITLE AND SUBTITLE Generator Set Environmental and Stability Testing 5a. CONTRACT NUMBER W56HZV-09-C-0100 5b. GRANT NUMBER 5c. PROGRAM

NASA Glenn Research Center Support of the Advanced Stirling Radioisotope Generator Project

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Wong, Wayne A.

2015-01-01

A high-efficiency radioisotope power system was being developed for long-duration NASA space science missions. The U.S. Department of Energy (DOE) managed a flight contract with Lockheed Martin Space Systems Company to build Advanced Stirling Radioisotope Generators (ASRGs), with support from NASA Glenn Research Center. DOE initiated termination of that contract in late 2013, primarily due to budget constraints. Sunpower, Inc., held two parallel contracts to produce Advanced Stirling Convertors (ASCs), one with Lockheed Martin to produce ASC-F flight units, and one with Glenn for the production of ASC-E3 engineering unit "pathfinders" that are built to the flight design. In support of those contracts, Glenn provided testing, materials expertise, Government-furnished equipment, inspection capabilities, and related data products to Lockheed Martin and Sunpower. The technical support included material evaluations, component tests, convertor characterization, and technology transfer. Material evaluations and component tests were performed on various ASC components in order to assess potential life-limiting mechanisms and provide data for reliability models. Convertor level tests were conducted to characterize performance under operating conditions that are representative of various mission conditions. Despite termination of the ASRG flight development contract, NASA continues to recognize the importance of high-efficiency ASC power conversion for Radioisotope Power Systems (RPS) and continues investment in the technology, including the continuation of the ASC-E3 contract. This paper describes key Government support for the ASRG project and future tests to be used to provide data for ongoing reliability assessments.

Weaker Seniors Exhibit Motor Cortex Hypoexcitability and Impairments in Voluntary Activation

PubMed Central

Taylor, Janet L.; Hong, S. Lee; Law, Timothy D.; Russ, David W.

2015-01-01

Background. Weakness predisposes seniors to a fourfold increase in functional limitations. The potential for age-related degradation in nervous system function to contribute to weakness and physical disability has garnered much interest of late. In this study, we tested the hypothesis that weaker seniors have impairments in voluntary (neural) activation and increased indices of GABAergic inhibition of the motor cortex, assessed using transcranial magnetic stimulation. Methods. Young adults (N = 46; 21.2±0.5 years) and seniors (N = 42; 70.7±0.9 years) had their wrist flexion strength quantified along with voluntary activation capacity (by comparing voluntary and electrically evoked forces). Single-pulse transcranial magnetic stimulation was used to measure motor-evoked potential amplitude and silent period duration during isometric contractions at 15% and 30% of maximum strength. Paired-pulse transcranial magnetic stimulation was used to measure intracortical facilitation and short-interval and long-interval intracortical inhibition. The primary analysis compared seniors to young adults. The secondary analysis compared stronger seniors (top two tertiles) to weaker seniors (bottom tertile) based on strength relative to body weight. Results. The most novel findings were that weaker seniors exhibited: (i) a 20% deficit in voluntary activation; (ii) ~20% smaller motor-evoked potentials during the 30% contraction task; and (iii) nearly twofold higher levels of long-interval intracortical inhibition under resting conditions. Conclusions. These findings indicate that weaker seniors exhibit significant impairments in voluntary activation, and that this impairment may be mechanistically associated with increased GABAergic inhibition of the motor cortex. PMID:25834195

Shuttle Flight Operations Contract Generator Maintenance Facility Land Use Control Implementation Plan (LUCIP)

NASA Technical Reports Server (NTRS)

Applegate, Joseph L.

2014-01-01

This Land Use Control Implementation Plan (LUCIP) has been prepared to inform current and potential future users of the Kennedy Space Center (KSC) Shuttle Flight Operations Contract Generator Maintenance Facility (SFOC; SWMU 081; "the Site") of institutional controls that have been implemented at the Site1. Although there are no current unacceptable risks to human health or the environment associated with the SFOC, an institutional land use control (LUC) is necessary to prevent human health exposure to antimony-affected groundwater at the Site. Controls will include periodic inspection, condition certification, and agency notification.

Stochastic Stabilityfor Contracting Lorenz Maps and Flows

NASA Astrophysics Data System (ADS)

Metzger, R. J.

In a previous work [M], we proved the existence of absolutely continuous invariant measures for contracting Lorenz-like maps, and constructed Sinai-Ruelle-Bowen measures f or the flows that generate them. Here, we prove stochastic stability for such one-dimensional maps and use this result to prove that the corresponding flows generating these maps are stochastically stable under small diffusion-type perturbations, even though, as shown by Rovella [Ro], they are persistent only in a measure theoretical sense in a parameter space. For the one-dimensional maps we also prove strong stochastic stability in the sense of Baladi and Viana[BV].

Design, fabricate, and provide engineering support for radiosotope thermoelectric generators for NASA'S CRHF and CASSINI missions

NASA Astrophysics Data System (ADS)

The technical progress achieved during the period 11 January through 31 March 1991 on Contract DE-AC03-91SF18852.000 Radioisotope Thermoelectric Generators and ancillary activities is described. The system contract consists of the following tasks: (1) Spacecraft Integration and Liaison; (2) Engineering Support; (3) Safety; (4) Qualify Unicouple Fabrication; (5) ETG Fabrication, Assembly and Test; (6) GSE; (7) RTG Shipping and Launch Support; (8) Designs, Reviews, and Mission Applications; (9) Project Management, Quality Assurance and Reliability; and (10) CAGO Acquisition (Capital Funds). The progress achieved is broken down into these tasks.

New-generation stents compared with coronary bypass surgery for unprotected left main disease: A word of caution.

PubMed

Benedetto, Umberto; Taggart, David P; Sousa-Uva, Miguel; Biondi-Zoccai, Giuseppe; Di Franco, Antonino; Ohmes, Lucas B; Rahouma, Mohamed; Kamel, Mohamed; Caputo, Massimo; Girardi, Leonard N; Angelini, Gianni D; Gaudino, Mario

2018-05-01

With the advent of bare metal stents and drug-eluting stents, percutaneous coronary intervention has emerged as an alternative to coronary artery bypass grafting surgery for unprotected left main disease. However, whether the evolution of stents technology has translated into better results after percutaneous coronary intervention remains unclear. We aimed to compare coronary artery bypass grafting with stents of different generations for left main disease by performing a Bayesian network meta-analysis of available randomized controlled trials. All randomized controlled trials with at least 1 arm randomized to percutaneous coronary intervention with stents or coronary artery bypass grafting for left main disease were included. Bare metal stents and drug-eluting stents of first- and second-generation were compared with coronary artery bypass grafting. Poisson methods and Bayesian framework were used to compute the head-to-head incidence rate ratio and 95% credible intervals. Primary end points were the composite of death/myocardial infarction/stroke and repeat revascularization. Nine randomized controlled trials were included in the final analysis. Six trials compared percutaneous coronary intervention with coronary artery bypass grafting (n = 4654), and 3 trials compared different types of stents (n = 1360). Follow-up ranged from 6 months to 5 years. Second-generation drug-eluting stents (incidence rate ratio, 1.3; 95% credible interval, 1.1-1.6), but not bare metal stents (incidence rate ratio, 0.63; 95% credible interval, 0.27-1.4), and first-generation drug-eluting stents (incidence rate ratio, 0.85; 95% credible interval, 0.65-1.1) were associated with a significantly increased risk of death/myocardial infarction/stroke when compared with coronary artery bypass grafting. When compared with coronary artery bypass grafting, the highest risk of repeat revascularization was observed for bare metal stents (hazard ratio, 5.1; 95% confidence interval, 2.1-14), whereas first-generation drug-eluting stents (incidence rate ratio, 1.8; 95% confidence interval, 1.4-2.4) and second-generation drug-eluting stents (incidence rate ratio, 1.8; 95% confidence interval, 1.4-2.4) were comparable. The introduction of new-generation drug-eluting stents did not translate into better outcomes for percutaneous coronary intervention when compared with coronary artery bypass grafting. Copyright © 2017 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Contractile and mechanical properties of epithelia with perturbed actomyosin dynamics.

PubMed

Fischer, Sabine C; Blanchard, Guy B; Duque, Julia; Adams, Richard J; Arias, Alfonso Martinez; Guest, Simon D; Gorfinkiel, Nicole

2014-01-01

Mechanics has an important role during morphogenesis, both in the generation of forces driving cell shape changes and in determining the effective material properties of cells and tissues. Drosophila dorsal closure has emerged as a reference model system for investigating the interplay between tissue mechanics and cellular activity. During dorsal closure, the amnioserosa generates one of the major forces that drive closure through the apical contraction of its constituent cells. We combined quantitation of live data, genetic and mechanical perturbation and cell biology, to investigate how mechanical properties and contraction rate emerge from cytoskeletal activity. We found that a decrease in Myosin phosphorylation induces a fluidization of amnioserosa cells which become more compliant. Conversely, an increase in Myosin phosphorylation and an increase in actin linear polymerization induce a solidification of cells. Contrary to expectation, these two perturbations have an opposite effect on the strain rate of cells during DC. While an increase in actin polymerization increases the contraction rate of amnioserosa cells, an increase in Myosin phosphorylation gives rise to cells that contract very slowly. The quantification of how the perturbation induced by laser ablation decays throughout the tissue revealed that the tissue in these two mutant backgrounds reacts very differently. We suggest that the differences in the strain rate of cells in situations where Myosin activity or actin polymerization is increased arise from changes in how the contractile forces are transmitted and coordinated across the tissue through ECadherin-mediated adhesion. Altogether, our results show that there is an optimal level of Myosin activity to generate efficient contraction and suggest that the architecture of the actin cytoskeleton and the dynamics of adhesion complexes are important parameters for the emergence of coordinated activity throughout the tissue.

Contractile and Mechanical Properties of Epithelia with Perturbed Actomyosin Dynamics

PubMed Central

Fischer, Sabine C.; Blanchard, Guy B.; Duque, Julia; Adams, Richard J.; Arias, Alfonso Martinez; Guest, Simon D.; Gorfinkiel, Nicole

2014-01-01

Mechanics has an important role during morphogenesis, both in the generation of forces driving cell shape changes and in determining the effective material properties of cells and tissues. Drosophila dorsal closure has emerged as a reference model system for investigating the interplay between tissue mechanics and cellular activity. During dorsal closure, the amnioserosa generates one of the major forces that drive closure through the apical contraction of its constituent cells. We combined quantitation of live data, genetic and mechanical perturbation and cell biology, to investigate how mechanical properties and contraction rate emerge from cytoskeletal activity. We found that a decrease in Myosin phosphorylation induces a fluidization of amnioserosa cells which become more compliant. Conversely, an increase in Myosin phosphorylation and an increase in actin linear polymerization induce a solidification of cells. Contrary to expectation, these two perturbations have an opposite effect on the strain rate of cells during DC. While an increase in actin polymerization increases the contraction rate of amnioserosa cells, an increase in Myosin phosphorylation gives rise to cells that contract very slowly. The quantification of how the perturbation induced by laser ablation decays throughout the tissue revealed that the tissue in these two mutant backgrounds reacts very differently. We suggest that the differences in the strain rate of cells in situations where Myosin activity or actin polymerization is increased arise from changes in how the contractile forces are transmitted and coordinated across the tissue through ECadherin-mediated adhesion. Altogether, our results show that there is an optimal level of Myosin activity to generate efficient contraction and suggest that the architecture of the actin cytoskeleton and the dynamics of adhesion complexes are important parameters for the emergence of coordinated activity throughout the tissue. PMID:24759936

The influence of iris color on the pupillary light reflex.

PubMed

Bergamin, O; Schoetzau, A; Sugimoto, K; Zulauf, M

1998-08-01

This study was carried out to investigate the effect of iris color on the pupillary light reflex (PLR) in normal healthy volunteers. Pupil perimetry was performed on 50 healthy volunteers with the Octopus 1-2-3 automated perimeter. Within the 30-deg visual field, 33 test locations were investigated four times. Stimulus parameters were Goldmann size V (1.72 degrees), intensity 1632 cd/m2, stimulus time 200 ms, background illumination 0 cd/m2, and interstimulus interval 3 s. Pupillometric parameters studied were initial pupil size, amplitude (magnitude of pupillary contraction), latency time, contraction time, pre-PLR movement, contraction velocity, and redilation velocity. Pupillometric parameters were investigated by analysis of variance by the independent variables blue and brown irides. Iris color (blue vs brown) influenced statistically significantly (P < 0.05) amplitude (0.504 mm vs 0.594 mm), contraction time (401 ms vs 407 ms), contraction velocity (13.75 mm2/s vs 16.01 mm2/s), and redilation velocity (4.80 mm2/s vs 5.66 mm2/s). Iris color did not influence initial pupil size (4.78 mm vs 4.83 mm), latency time (520 mm vs 521 ms), and pre-PLR movement (0.328 mm2/s vs 0.325 mm2/s). Pupillary contraction amplitude and velocity depended on iris color, whereas pupil size and latency time were independent of iris color. Therefore, iris color might be considered when, evaluating pupillary movements in pupil perimetry.

Hydraulic Analyses of Sni-A-Bar Creek and Selected Tributaries at Grain Valley, Jackson County, Missouri

USGS Publications Warehouse

Rydlund, Jr., Paul H.; Otero-Benitez, William; Heimann, David C.

2008-01-01

A study was done by the U.S. Geological Survey, in cooperation with the city of Grain Valley, Jackson County, Missouri, to simulate the hydraulic characteristics of Sni-A-Bar Creek and selected tributaries within the corporate limits. The 10-, 50-, 100-, and 500-year recurrence interval streamflows were simulated to determine potential backwater effects on the Sni-A-Bar Creek main stem and to delineate flood-plain boundaries on the tributaries. The water-surface profiles through the bridge structures within the model area indicated that backwater effects from the constrictions were not substantial. The water-surface profile of Sni-A-Bar Creek generated from the one- and two-dimensional models indicated that the Gateway Western Railroad structure provided the greatest amount of contraction of flow within the modeled area. The results at the location of the upstream face of the railroad structure indicated a change in water-surface elevation from 0.2 to 0.8 foot (corresponding to simulated 10-year and 500-year flood occurrences). Results from all analyses indicated minimal backwater effects as a result of an overall minimal energy grade line slope and velocity head along Sni-A-Bar Creek. The flood plains for the 100-year recurrence interval floods on the Sni-A-Bar tributaries were mapped to show the extent of inundated areas. The updated flooding characteristics will allow city managers to contrast changes in flood risk and zoning as determined through the National Flood Insurance Program.

Ajmaline blocks INa and IKr without eliciting differences between Brugada syndrome patient and control human pluripotent stem cell-derived cardiac clusters.

PubMed

Miller, Duncan C; Harmer, Stephen C; Poliandri, Ariel; Nobles, Muriel; Edwards, Elizabeth C; Ware, James S; Sharp, Tyson V; McKay, Tristan R; Dunkel, Leo; Lambiase, Pier D; Tinker, Andrew

2017-12-01

The class Ia anti-arrhythmic drug ajmaline is used clinically to unmask latent type I ECG in Brugada syndrome (BrS) patients, although its mode of action is poorly characterised. Our aims were to identify ajmaline's mode of action in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs), and establish a simple BrS hiPSC platform to test whether differences in ajmaline response could be determined between BrS patients and controls. Control hiPSCs were differentiated into spontaneously contracting cardiac clusters. It was found using multi electrode array (MEA) that ajmaline treatment significantly lengthened cluster activation-recovery interval. Patch clamping of single CMs isolated from clusters revealed that ajmaline can block both I Na and I Kr . Following generation of hiPSC lines from BrS patients (absent of pathogenic SCN5A sodium channel mutations), analysis of hiPSC-CMs from patients and controls revealed that differentiation and action potential parameters were similar. Comparison of cardiac clusters by MEA showed that ajmaline lengthened activation-recovery interval consistently across all lines. We conclude that ajmaline can block both depolarisation and repolarisation of hiPSC-CMs at the cellular level, but that a more refined integrated tissue model may be necessary to elicit differences in its effect between BrS patients and controls. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Two-Rockets Thought Experiment

NASA Astrophysics Data System (ADS)

Smarandache, Florentin

2014-03-01

Let n>=2 be identical rockets: R1 ,R2 , ..., Rn. Each of them moving at constant different velocities respectively v1, v2, ..., vn on parallel directions in the same sense. In each rocket there is a light clock, the observer on earth also has a light clock. All n + 1 light clocks are identical and synchronized. The proper time Δt' in each rocket is the same. Let's focus on two arbitrary rockets Ri and Rjfrom the previous n rockets. Let's suppose, without loss of generality, that their speeds verify vi

2008 Enterprise Transition Plan (ETP)

DTIC Science & Technology

2008-09-30

of contract data to entitlement systems . • Close coordination with contracting office resulted in an increase in the successful electronic ...2005 to the Fall of 2007, the DBSMC approved funding for 304 individual systems , representing $7.5B in modernization investment funding. These...industry has developed the processes and learned its lessons from working in Africa for generations . Leveraging this experience is

Contracted or uncontracted polarization functions? Comment on Dunning's correlation-consistent basis sets

NASA Astrophysics Data System (ADS)

Hashimoto, Tomohiro; Hirao, Kimihiko; Tatewaki, Hiroshi

1997-07-01

For the sake of computational economy, the polarization functions given by Dunning are contracted by multiconfigurational SCF calculations for H, B, C, N, O, F and Ne atoms. For the first-row atoms, B through Ne, the generated contracted polarization functions are ( 2 d/1 d) and ( 3 d/2 d) and for H they are ( 2 p/1 p), ( 3 p/1 p), and ( 3 p/2 p) where the numbers before and after the slash are the numbers of uncontracted and contracted polarization functions. Numerical examples on some diatomic molecules and benzene illustrate a large improvement in going from ( 1 d/1 dto ( 2 d/1 d) for various molecular properties.

Probabilities of Possible Future Prices (Short-Term Energy Outlook Supplement April 2010)

EIA Publications

2010-01-01

The Energy Information Administration introduced a monthly analysis of energy price volatility and forecast uncertainty in the October 2009 Short-Term Energy Outlook (STEO). Included in the analysis were charts portraying confidence intervals around the New York Mercantile Exchange (NYMEX) futures prices of West Texas Intermediate (equivalent to light sweet crude oil) and Henry Hub natural gas contracts.

78 FR 32498 - Self-Regulatory Organizations; NASDAQ OMX PHLX LLC; Notice of Filing and Immediate Effectiveness...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-30

... Change Relating to $0.50 and $1 Strike Price Intervals for Classes in the Short Term Option Series... amend Rule 1012 (Series of Options Open for Trading) and Rule 1101A (Terms of Option Contracts) to give... Term Option Series Program (referred to as a ``Related non-Short Term Option series''), for the Related...

Locomotion of neutrally buoyant fish with flexible caudal fin.

PubMed

Iosilevskii, Gil

2016-06-21

Historically, burst-and-coast locomotion strategies have been given two very different explanations. The first one was based on the assumption that the drag of an actively swimming fish is greater than the drag of the same fish in motionless glide. Fish reduce the cost of locomotion by swimming actively during a part of the swimming interval, and gliding through the remaining part. The second one was based on the assumption that muscles perform efficiently only if their contraction rate exceeds a certain threshold. Fish reduce the cost of locomotion by using an efficient contraction rate during a part of the swimming interval, and gliding through the remaining part. In this paper, we suggest yet a third explanation. It is based on the assumption that propulsion efficiency of a swimmer can increase with thrust. Fish reduce the cost of locomotion by alternating high thrust, and hence more efficient, bursts with passive glides. The paper presents a formal analysis of the respective burst-and-coast strategy, shows that the locomotion efficiency can be practically as high as the propulsion efficiency during burst, and shows that the other two explanations can be considered particular cases of the present one. Copyright © 2016 Elsevier Ltd. All rights reserved.

Parallel Douglas-Kroll Energy and Gradients in NWChem. Estimating Scalar Relativistic Effects Using Douglas-Kroll Contracted Basis Sets.

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

De Jong, Wibe A.; Harrison, Robert J.; Dixon, David A.

A parallel implementation of the spin-free one-electron Douglas-Kroll(-Hess) Hamiltonian (DKH) in NWChem is discussed. An efficient and accurate method to calculate DKH gradients is introduced. It is shown that the use of standard (non-relativistic) contracted basis set can produce erroneous results for elements beyond the first row elements. The generation of DKH contracted cc-pVXZ (X = D, T, Q, 5) basis sets for H, He, B - Ne, Al - Ar, and Ga - Br will be discussed.

Mapping Active Stream Lengths as a Tool for Understanding Spatial Variations in Runoff Generation

NASA Astrophysics Data System (ADS)

Erwin, E. G.; Gannon, J. P.; Zimmer, M. A.

2016-12-01

Recent studies have shown temporary stream channels respond in complex ways to precipitation. By investigating how stream networks expand and recede throughout rain events, we may further develop our understanding of runoff generation. This study focused on mapping the expansion and contraction of the stream network in two headwater catchments characterized by differing soil depths and slopes, located in North Carolina, USA. The first is a 43 ha catchment located in the Southern Appalachian region, characterized by incised, steep slopes and soils of varying thickness. The second is a 3.3 ha catchment located in the Piedmont region, characterized as low relief with deep, highly weathered soils. Over a variety of flow conditions, surveys of the entire stream network were conducted at 10 m intervals to determine presence or absence of surface water. These surveys revealed several reaches within the networks that were intermittent, with perennial flow upstream and downstream. Furthermore, in some tributaries, the active stream head moved up the channel in response to precipitation and at others it remained anchored in place. Moreover, when repeat surveys were performed during the same storm, hysteresis was observed in active stream length variations: stream length was not the same on the rising limb and falling limb of the hydrograph. These observations suggest there are different geomorphological controls or runoff generation processes occurring spatially throughout these catchments. Observations of wide spatial and temporal variability of active stream length over a variety of flow conditions suggest runoff dynamics, generation mechanisms, and contributing flowpath depths producing streamflow may be highly variable and not easily predicted from streamflow observations at a fixed point. Finally, the observation of similar patterns in differing geomorphic regions suggests these processes extend beyond unique site characterizations.

Using Prediction Markets to Generate Probability Density Functions for Climate Change Risk Assessment

NASA Astrophysics Data System (ADS)

Boslough, M.

2011-12-01

Climate-related uncertainty is traditionally presented as an error bar, but it is becoming increasingly common to express it in terms of a probability density function (PDF). PDFs are a necessary component of probabilistic risk assessments, for which simple "best estimate" values are insufficient. Many groups have generated PDFs for climate sensitivity using a variety of methods. These PDFs are broadly consistent, but vary significantly in their details. One axiom of the verification and validation community is, "codes don't make predictions, people make predictions." This is a statement of the fact that subject domain experts generate results using assumptions within a range of epistemic uncertainty and interpret them according to their expert opinion. Different experts with different methods will arrive at different PDFs. For effective decision support, a single consensus PDF would be useful. We suggest that market methods can be used to aggregate an ensemble of opinions into a single distribution that expresses the consensus. Prediction markets have been shown to be highly successful at forecasting the outcome of events ranging from elections to box office returns. In prediction markets, traders can take a position on whether some future event will or will not occur. These positions are expressed as contracts that are traded in a double-action market that aggregates price, which can be interpreted as a consensus probability that the event will take place. Since climate sensitivity cannot directly be measured, it cannot be predicted. However, the changes in global mean surface temperature are a direct consequence of climate sensitivity, changes in forcing, and internal variability. Viable prediction markets require an undisputed event outcome on a specific date. Climate-related markets exist on Intrade.com, an online trading exchange. One such contract is titled "Global Temperature Anomaly for Dec 2011 to be greater than 0.65 Degrees C." Settlement is based global temperature anomaly data published by NASS GISS. Typical climate contracts predict the probability of a specified future temperature, but not the probability density or best estimate. One way to generate a probability distribution would be to create a family of contracts over a range of specified temperatures and interpret the price of each contract as its exceedance probability. The resulting plot of probability vs. anomaly is the market-based cumulative density function. The best estimate can be determined by interpolation, and the market-based uncertainty estimate can be based on the spread. One requirement for an effective prediction market is liquidity. Climate contracts are currently considered somewhat of a novelty and often lack sufficient liquidity, but climate change has the potential to generate both tremendous losses for some (e.g. agricultural collapse and extreme weather events) and wealth for others (access to natural resources and trading routes). Use of climate markets by large stakeholders has the potential to generate the liquidity necessary to make them viable. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DoE's NNSA under contract DE-AC04-94AL85000.

Mirror illusion reduces motor cortical inhibition in the ipsilateral primary motor cortex during forceful unilateral muscle contractions.

PubMed

Zult, Tjerk; Goodall, Stuart; Thomas, Kevin; Hortobágyi, Tibor; Howatson, Glyn

2015-04-01

Forceful, unilateral contractions modulate corticomotor paths targeting the resting, contralateral hand. However, it is unknown whether mirror-viewing of a slowly moving but forcefully contracting hand would additionally affect these paths. Here we examined corticospinal excitability and short-interval intracortical inhibition (SICI) of the right-ipsilateral primary motor cortex (M1) in healthy young adults under no-mirror and mirror conditions at rest and during right wrist flexion at 60% maximal voluntary contraction (MVC). During the no-mirror conditions neither hand was visible, whereas in the mirror conditions participants looked at the right hand's reflection in the mirror. Corticospinal excitability increased during contractions in the left flexor carpi radialis (FCR) (contraction 0.41 mV vs. rest 0.21 mV) and extensor carpi radialis (ECR) (contraction 0.56 mV vs. rest 0.39 mV), but there was no mirror effect (FCR: P = 0.743, ηp (2) = 0.005; ECR: P = 0.712, ηp (2) = 0.005). However, mirror-viewing of the contracting and moving wrist attenuated SICI relative to test pulse in the left FCR by ∼9% compared with the other conditions (P < 0.05, d ≥ 0.62). Electromyographic activity in the resting left hand prior to stimulation was not affected by the mirror (FCR: P = 0.255, ηp (2) = 0.049; ECR: P = 0.343, ηp (2) = 0.035) but increased twofold during contractions. Thus viewing the moving hand in the mirror and not just the mirror image of the nonmoving hand seems to affect motor cortical inhibitory networks in the M1 associated with the mirror image. Future studies should determine whether the use of a mirror could increase interlimb transfer produced by cross-education, especially in patient groups with unilateral orthopedic and neurological conditions. Copyright © 2015 the American Physiological Society.

Mirror illusion reduces motor cortical inhibition in the ipsilateral primary motor cortex during forceful unilateral muscle contractions

PubMed Central

Goodall, Stuart; Thomas, Kevin; Hortobágyi, Tibor; Howatson, Glyn

2015-01-01

Forceful, unilateral contractions modulate corticomotor paths targeting the resting, contralateral hand. However, it is unknown whether mirror-viewing of a slowly moving but forcefully contracting hand would additionally affect these paths. Here we examined corticospinal excitability and short-interval intracortical inhibition (SICI) of the right-ipsilateral primary motor cortex (M1) in healthy young adults under no-mirror and mirror conditions at rest and during right wrist flexion at 60% maximal voluntary contraction (MVC). During the no-mirror conditions neither hand was visible, whereas in the mirror conditions participants looked at the right hand's reflection in the mirror. Corticospinal excitability increased during contractions in the left flexor carpi radialis (FCR) (contraction 0.41 mV vs. rest 0.21 mV) and extensor carpi radialis (ECR) (contraction 0.56 mV vs. rest 0.39 mV), but there was no mirror effect (FCR: P = 0.743, ηp2 = 0.005; ECR: P = 0.712, ηp2 = 0.005). However, mirror-viewing of the contracting and moving wrist attenuated SICI relative to test pulse in the left FCR by ∼9% compared with the other conditions (P < 0.05, d ≥ 0.62). Electromyographic activity in the resting left hand prior to stimulation was not affected by the mirror (FCR: P = 0.255, ηp2 = 0.049; ECR: P = 0.343, ηp2 = 0.035) but increased twofold during contractions. Thus viewing the moving hand in the mirror and not just the mirror image of the nonmoving hand seems to affect motor cortical inhibitory networks in the M1 associated with the mirror image. Future studies should determine whether the use of a mirror could increase interlimb transfer produced by cross-education, especially in patient groups with unilateral orthopedic and neurological conditions. PMID:25632077

Microfluidic chest cavities reveal that transmural pressure controls the rate of lung development.

PubMed

Nelson, Celeste M; Gleghorn, Jason P; Pang, Mei-Fong; Jaslove, Jacob M; Goodwin, Katharine; Varner, Victor D; Miller, Erin; Radisky, Derek C; Stone, Howard A

2017-12-01

Mechanical forces are increasingly recognized to regulate morphogenesis, but how this is accomplished in the context of the multiple tissue types present within a developing organ remains unclear. Here, we use bioengineered 'microfluidic chest cavities' to precisely control the mechanical environment of the fetal lung. We show that transmural pressure controls airway branching morphogenesis, the frequency of airway smooth muscle contraction, and the rate of developmental maturation of the lungs, as assessed by transcriptional analyses. Time-lapse imaging reveals that branching events are synchronized across distant locations within the lung, and are preceded by long-duration waves of airway smooth muscle contraction. Higher transmural pressure decreases the interval between systemic smooth muscle contractions and increases the rate of morphogenesis of the airway epithelium. These data reveal that the mechanical properties of the microenvironment instruct crosstalk between different tissues to control the development of the embryonic lung. © 2017. Published by The Company of Biologists Ltd.

Random Walks on Homeo( S 1)

NASA Astrophysics Data System (ADS)

Malicet, Dominique

2017-12-01

In this paper, we study random walks {g_n=f_{n-1}\\ldots f_0} on the group Homeo ( S 1) of the homeomorphisms of the circle, where the homeomorphisms f k are chosen randomly, independently, with respect to a same probability measure {ν}. We prove that under the only condition that there is no probability measure invariant by {ν}-almost every homeomorphism, the random walk almost surely contracts small intervals. It generalizes what has been known on this subject until now, since various conditions on {ν} were imposed in order to get the phenomenon of contractions. Moreover, we obtain the surprising fact that the rate of contraction is exponential, even in the lack of assumptions of smoothness on the f k 's. We deduce various dynamical consequences on the random walk ( g n ): finiteness of ergodic stationary measures, distribution of the trajectories, asymptotic law of the evaluations, etc. The proof of the main result is based on a modification of the Ávila-Viana's invariance principle, working for continuous cocycles on a space fibred in circles.

Effect of Aging on Tongue Protrusion Forces in Rats

PubMed Central

Nagai, Hiromi; Russell, John A.; Jackson, Michelle A.

2010-01-01

The purpose of this study was to ascertain the effect of aging on muscle contractile properties associated with tongue protrusion in a rat model. Fischer 344/Brown Norway hybrid rats, ten young (9 months old) and ten old (32 months old), were used to measure protrusive contractile properties. Results showed a significant reduction in tetanic forces in the old animals. The following measures of muscle contraction were not different between age groups: mean twitch contraction force, twitch contraction time, twitch contraction half-decay time, and a calculated measure of fatigability. In conclusion, aging influenced protrusive tongue muscle contractions in a rat model such that tetanic forces were reduced. The reduction of tetanus force may parallel findings in human subjects relative to isometric tongue force generation and may be associated with age-related disorders of swallowing. PMID:17694408

Synchronous monitoring of muscle dynamics and electromyogram

NASA Astrophysics Data System (ADS)

Zakir Hossain, M.; Grill, Wolfgang

2011-04-01

A non-intrusive novel detection scheme has been implemented to detect the lateral muscle extension, force of the skeletal muscle and the motor action potential (EMG) synchronously. This allows the comparison of muscle dynamics and EMG signals as a basis for modeling and further studies to determine which architectural parameters are most sensitive to changes in muscle activity. For this purpose the transmission time for ultrasonic chirp signal in the frequency range of 100 kHz to 2.5 MHz passing through the muscle under observation and respective motor action potentials are recorded synchronously to monitor and quantify biomechanical parameters related to muscle performance. Additionally an ultrasonic force sensor has been employed for monitoring. Ultrasonic traducers are placed on the skin to monitor muscle expansion. Surface electrodes are placed suitably to pick up the potential for activation of the monitored muscle. Isometric contraction of the monitored muscle is ensured by restricting the joint motion with the ultrasonic force sensor. Synchronous monitoring was initiated by a software activated audio beep starting at zero time of the subsequent data acquisition interval. Computer controlled electronics are used to generate and detect the ultrasonic signals and monitor the EMG signals. Custom developed software and data analysis is employed to analyze and quantify the monitored data. Reaction time, nerve conduction speed, latent period between the on-set of EMG signals and muscle response, degree of muscle activation and muscle fatigue development, rate of energy expenditure and motor neuron recruitment rate in isometric contraction, and other relevant parameters relating to muscle performance have been quantified with high spatial and temporal resolution.

Effects of Plyometric Versus Concentric and Eccentric Conditioning Contractions on Upper-Body Postactivation Potentiation.

PubMed

Ulrich, Gert; Parstorfer, Mario

2017-07-01

There are limited data on postactivation potentiation's (PAP) effects after plyometric conditioning contractions (CCs), especially in the upper body. This study compared plyometric CCs with concentric-eccentric and eccentric CCs aiming to improve upper-body power performance due to a PAP effect. Sixteen resistance-trained males completed 3 experimental trials in a randomized order that comprised either a plyometric (PLY), a concentric-eccentric (CON), or an eccentric-only (ECC) CC. Maximal muscle performance, as determined by a ballistic bench-press throw, was measured before (baseline) and 1, 4, 8, 12, and 16 min after each CC. Compared with baseline, bench-press power was significantly enhanced only in CON (P = .046, ES = 0.21) after 8 min of recovery. However, the results obtained from the comparisons between baseline power performance and the individual best power performance for each subject after each CC stimulus showed significant increases in PLY (P < .001, ES = 0.31) and CON (P < .001, ES = 0.38). There was no significant improvement in ECC (P = .106, ES = 0.11). The results indicate that only CON CCs generated increases in bench-press power after 8 min of rest. However, considering an individual rest interval, PLY CCs led to an enhanced power performance in the bench-press exercise, and this increase was comparable to that induced by CON CCs. Due to the easy practical application before a competition, PLY CCs might be an interesting part of warm-up strategies aiming to improve upper-body power performance by reason of PAP.

Genetic visualization with an improved GCaMP calcium indicator reveals spatiotemporal activation of the spinal motor neurons in zebrafish

PubMed Central

Muto, Akira; Ohkura, Masamichi; Kotani, Tomoya; Higashijima, Shin-ichi; Nakai, Junichi; Kawakami, Koichi

2011-01-01

Animal behaviors are generated by well-coordinated activation of neural circuits. In zebrafish, embryos start to show spontaneous muscle contractions at 17 to 19 h postfertilization. To visualize how motor circuits in the spinal cord are activated during this behavior, we developed GCaMP-HS (GCaMP-hyper sensitive), an improved version of the genetically encoded calcium indicator GCaMP, and created transgenic zebrafish carrying the GCaMP-HS gene downstream of the Gal4-recognition sequence, UAS (upstream activation sequence). Then we performed a gene-trap screen and identified the SAIGFF213A transgenic fish that expressed Gal4FF, a modified version of Gal4, in a subset of spinal neurons including the caudal primary (CaP) motor neurons. We conducted calcium imaging using the SAIGFF213A; UAS:GCaMP-HS double transgenic embryos during the spontaneous contractions. We demonstrated periodic and synchronized activation of a set of ipsilateral motor neurons located on the right and left trunk in accordance with actual muscle movements. The synchronized activation of contralateral motor neurons occurred alternately with a regular interval. Furthermore, a detailed analysis revealed rostral-to-caudal propagation of activation of the ipsilateral motor neuron, which is similar to but much slower than the rostrocaudal delay observed during swimming in later stages. Our study thus demonstrated coordinated activities of the motor neurons during the first behavior in a vertebrate. We propose the GCaMP technology combined with the Gal4FF-UAS system is a powerful tool to study functional neural circuits in zebrafish. PMID:21383146

A Project Assessment of Stabilizing System of WT Generation using Rechargeable Battery

NASA Astrophysics Data System (ADS)

Kojima, Yasuhiro; Takano, Tomihiro; Tanikawa, Ryoichi; Takagi, Tetsuro; Hirooka, Koutaro; Kumagai, Sadatoshi

The expansion of the renewable energy introduction is examined as measures for controlling global warming. Wind power generation is expected as effective power resource, but the negative impact from the difficulty of an unstable output is concerned. In recent years, WT generation with contract of cut-of with shorting adjusting power and with rechargeable battery for stabilizing control are examined, but the introduction has not been accelerated yet because there is an influence in WT generation entrepreneur's business. In this paper, we make a brief summary of relation between the fluctuation of wind power generation and stability of electric power operation, and two types of approach; cut-off contract and stabilization using rechargeable battery. For the stabilization using battery, there are two methods, one is reduction control and the other is constant control. We propose a new control method for constant control based on profit optimization considering WT generation forecast and its risk of deviation. We also propose the estimation method for the .limitation of battery installation. Simulation results show the efficiency of our proposed methods.

Models of supply function equilibrium with applications to the electricity industry

NASA Astrophysics Data System (ADS)

Aromi, J. Daniel

Electricity market design requires tools that result in a better understanding of incentives of generators and consumers. Chapter 1 and 2 provide tools and applications of these tools to analyze incentive problems in electricity markets. In chapter 1, models of supply function equilibrium (SFE) with asymmetric bidders are studied. I prove the existence and uniqueness of equilibrium in an asymmetric SFE model. In addition, I propose a simple algorithm to calculate numerically the unique equilibrium. As an application, a model of investment decisions is considered that uses the asymmetric SFE as an input. In this model, firms can invest in different technologies, each characterized by distinct variable and fixed costs. In chapter 2, option contracts are introduced to a supply function equilibrium (SFE) model. The uniqueness of the equilibrium in the spot market is established. Comparative statics results on the effect of option contracts on the equilibrium price are presented. A multi-stage game where option contracts are traded before the spot market stage is considered. When contracts are optimally procured by a central authority, the selected profile of option contracts is such that the spot market price equals marginal cost for any load level resulting in a significant reduction in cost. If load serving entities (LSEs) are price takers, in equilibrium, there is no trade of option contracts. Even when LSEs have market power, the central authority's solution cannot be implemented in equilibrium. In chapter 3, we consider a game in which a buyer must repeatedly procure an input from a set of firms. In our model, the buyer is able to sign long term contracts that establish the likelihood with which the next period contract is awarded to an entrant or the incumbent. We find that the buyer finds it optimal to favor the incumbent, this generates more intense competition between suppliers. In a two period model we are able to completely characterize the optimal mechanism.

Intervals for posttest probabilities: a comparison of 5 methods.

PubMed

Mossman, D; Berger, J O

2001-01-01

Several medical articles discuss methods of constructing confidence intervals for single proportions and the likelihood ratio, but scant attention has been given to the systematic study of intervals for the posterior odds, or the positive predictive value, of a test. The authors describe 5 methods of constructing confidence intervals for posttest probabilities when estimates of sensitivity, specificity, and the pretest probability of a disorder are derived from empirical data. They then evaluate each method to determine how well the intervals' coverage properties correspond to their nominal value. When the estimates of pretest probabilities, sensitivity, and specificity are derived from more than 80 subjects and are not close to 0 or 1, all methods generate intervals with appropriate coverage properties. When these conditions are not met, however, the best-performing method is an objective Bayesian approach implemented by a simple simulation using a spreadsheet. Physicians and investigators can generate accurate confidence intervals for posttest probabilities in small-sample situations using the objective Bayesian approach.

Recovery of time evolution of Grad-Shafranov equilibria from single-spacecraft data: Benchmarking and application to a flux transfer event

NASA Astrophysics Data System (ADS)

Hasegawa, Hiroshi; Sonnerup, Bengt U. Ã.-.; Nakamura, Takuma K. M.

2010-11-01

First results are presented of a method, developed by Sonnerup and Hasegawa (2010), for analyzing time evolution of magnetohydrostatic Grad-Shafranov (GS) equilibria, using data recorded by an observing probe as it traverses a quasi-static, two-dimensional (2D), magnetic-field/plasma structure. The method recovers spatial initial values used in the classical GS reconstruction for an interval before and after the time of actual measurements, by advancing them backward and forward in time based on a set of equations for an incompressible plasma; the consequence is generation of multiple GS maps or a movie of the 2D field structure. The method is successfully benchmarked by use of a 2D magnetohydrodynamic simulation of time-dependent magnetic reconnection, and then is applied to a flux transfer event (FTE) seen by the Cluster spacecraft at the dayside high-latitude magnetopause. The application shows that the field lines constituting the FTE flux rope were contracting toward its center as a result of modest convective flow in the region around the core of the flux rope.

Structural and molecular conformation of myosin in intact muscle fibers by second harmonic generation

NASA Astrophysics Data System (ADS)

Nucciotti, V.; Stringari, C.; Sacconi, L.; Vanzi, F.; Linari, M.; Piazzesi, G.; Lombardi, V.; Pavone, F. S.

2009-02-01

Recently, the use of Second Harmonic Generation (SHG) for imaging biological samples has been explored with regard to intrinsic SHG in highly ordered biological samples. As shown by fractional extraction of proteins, myosin is the source of SHG signal in skeletal muscle. SHG is highly dependent on symmetries and provides selective information on the structural order and orientation of the emitting proteins and the dynamics of myosin molecules responsible for the mechano-chemical transduction during contraction. We characterise the polarization-dependence of SHG intensity in three different physiological states: resting, rigor and isometric tetanic contraction in a sarcomere length range between 2.0 μm and 4.0 μm. The orientation of motor domains of the myosin molecules is dependent on their physiological states and modulate the SHG signal. We can discriminate the orientation of the emitting dipoles in four different molecular conformations of myosin heads in intact fibers during isometric contraction, in resting and rigor. We estimate the contribution of the myosin motor domain to the total second order bulk susceptibility from its molecular structure and its functional conformation. We demonstrate that SHG is sensitive to the fraction of ordered myosin heads by disrupting the order of myosin heads in rigor with an ATP analog. We estimate the fraction of myosin motors generating the isometric force in the active muscle fiber from the dependence of the SHG modulation on the degree of overlap between actin and myosin filaments during an isometric contraction.

Test-retest reliability of muscle fiber conduction velocity and fractal dimension of surface EMG during isometric contractions.

PubMed

Beretta-Piccoli, Matteo; D'Antona, Giuseppe; Zampella, Cristian; Barbero, Marco; Clijsen, Ron; Cescon, Corrado

2017-04-01

The aim of this study was to determine the test-retest reliability of muscle fiber conduction velocity (CV) and fractal dimension (FD) obtained from multichannel surface electromyographic (sEMG) recordings. Forty healthy recreationally active subjects (20 men and 20 women) performed two elbow flexions on two trials with a 1 week interval. The first was a 20% maximal voluntary contraction (MVC) of 120 s, and the second at 60% MVC held until exhaustion. sEMG signals were detected from the biceps brachii, using bi-dimensional arrays. Initial values and slope of CV and FD were used for the reliability analysis. The intraclass correlation coefficient (ICC) values for the isometric contraction at 20% MVC were (-0.09) and 0.67 for CV and FD respectively; whereas the ICC values at 60% MVC were 0.78 and 0.82 for CV and FD respectively. The Bland Altman plots for the two isometric contractions showed a mean difference close to zero, with no evident outliers between the repeated measurements: at 20% MVC 0.001 53 for FD and  -0.0277 for CV, and at 60% MVC 0.006 66 for FD and 0.009 07 for CV. Overall, our findings suggest that during isometric fatiguing contractions, CV and FD slopes are reliable variables, with potential application in clinical populations.

Repetitive muscle compression reduces vascular mechano-sensitivity and the hyperemic response to muscle contraction.

PubMed

Messere, A; Turturici, M; Millo, G; Roatta, S

2017-06-01

Animal studies have shown that the rapid hyperemic response to external muscle compression undergoes inactivation upon repetitive stimulation, but this phenomenon has never been observed in humans. The aim of the present study was to determine whether 1) the vascular mechano-sensitivity underlying muscle compression-induced hyperemia is inactivated in an inter-stimulus interval (ISI)-dependent fashion upon repetitive stimulation, as suggested by animal studies, and 2) whether such inactivation also attenuates contraction-induced hyperemia. Brachial artery blood flow was measured by echo Doppler sonography in 13 healthy adults in response to 1) single and repetitive cuff muscle compression (CMC) of the forearm (20 CMCs, 1 s ISI); 2) a sequence of CMC delivered at decreasing ISI from 120 to 2 s; and 3) electrically-stimulated contraction of the forearm muscles before and after repetitive CMC. The peak amplitude of hyperemia in response to CMC normalized to baseline decreased from 2.2 ± 0.6 to 1.4 ± 0.4 after repetitive CMC and, in general, was decreased at ISI < 240 s. The peak amplitude of contraction-induced hyperemia was attenuated after as compared to before repeated CMC (1.7 ± 0.4 and 2.6 ± 0.6, respectively). Mechano-sensitivity of the vascular network can be conditioned by previous mechanical stimulation, and such preconditioning may substantially decrease contraction-induced hyperemia.

Neurotization of the biceps muscle by end-to-side neurorraphy between ulnar and musculocutaneous nerves. A series of five cases.

PubMed

Franciosi, L F; Modestti, C; Mueller, S F

1998-01-01

Three patients with avulsed C5, C6, and C7 roots and two patients with avulsed C5 and C6 roots after trauma of the brachial plexus, were treated by neurotization of the biceps using nerve fibers derived from the ulnar nerve and obtained by end-to-side neurorraphy between the ulnar and musculocutaneous nerves. The age of patients ranged from 19 to 45. The interval between the accident and surgery was 2 to 13 months. Return of biceps contraction was observed 4 to 6 months after surgery. Four patients recovered grade 4 elbow flexion. One 45-year-old patient did not obtain any biceps contraction after 9 months.

Motor unit firing rates and synchronisation affect the fractal dimension of simulated surface electromyogram during isometric/isotonic contraction of vastus lateralis muscle.

PubMed

Mesin, Luca; Dardanello, Davide; Rainoldi, Alberto; Boccia, Gennaro

2016-12-01

During fatiguing contractions, many adjustments in motor units behaviour occur: decrease in muscle fibre conduction velocity; increase in motor units synchronisation; modulation of motor units firing rate; increase in variability of motor units inter-spike interval. We simulated the influence of all these adjustments on synthetic EMG signals in isometric/isotonic conditions. The fractal dimension of the EMG signal was found mainly influenced by motor units firing behaviour, being affected by both firing rate and synchronisation level, and least affected by muscle fibre conduction velocity. None of the calculated EMG indices was able to discriminate between firing rate and motor units synchronisation. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Rigor mortis at the myocardium investigated by post-mortem magnetic resonance imaging.

PubMed

Bonzon, Jérôme; Schön, Corinna A; Schwendener, Nicole; Zech, Wolf-Dieter; Kara, Levent; Persson, Anders; Jackowski, Christian

2015-12-01

Post-mortem cardiac MR exams present with different contraction appearances of the left ventricle in cardiac short axis images. It was hypothesized that the grade of post-mortem contraction may be related to the post-mortem interval (PMI) or cause of death and a phenomenon caused by internal rigor mortis that may give further insights in the circumstances of death. The cardiac contraction grade was investigated in 71 post-mortem cardiac MR exams (mean age at death 52 y, range 12-89 y; 48 males, 23 females). In cardiac short axis images the left ventricular lumen volume as well as the left ventricular myocardial volume were assessed by manual segmentation. The quotient of both (LVQ) represents the grade of myocardial contraction. LVQ was correlated to the PMI, sex, age, cardiac weight, body mass and height, cause of death and pericardial tamponade when present. In cardiac causes of death a separate correlation was investigated for acute myocardial infarction cases and arrhythmic deaths. LVQ values ranged from 1.99 (maximum dilatation) to 42.91 (maximum contraction) with a mean of 15.13. LVQ decreased slightly with increasing PMI, however without significant correlation. Pericardial tamponade positively correlated with higher LVQ values. Variables such as sex, age, body mass and height, cardiac weight and cause of death did not correlate with LVQ values. There was no difference in LVQ values for myocardial infarction without tamponade and arrhythmic deaths. Based on the observation in our investigated cases, the phenomenon of post-mortem myocardial contraction cannot be explained by the influence of the investigated variables, except for pericardial tamponade cases. Further research addressing post-mortem myocardial contraction has to focus on other, less obvious factors, which may influence the early post-mortem phase too. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Pupils' Visual Representations in Standard and Problematic Problem Solving in Mathematics: Their Role in the Breach of the Didactical Contract

ERIC Educational Resources Information Center

Deliyianni, Eleni; Monoyiou, Annita; Elia, Iliada; Georgiou, Chryso; Zannettou, Eleni

2009-01-01

This study investigated the modes of representations generated by kindergarteners and first graders while solving standard and problematic problems in mathematics. Furthermore, it examined the influence of pupils' visual representations on the breach of the didactical contract rules in problem solving. The sample of the study consisted of 38…

A mathematical model of the coupled mechanisms of cell adhesion, contraction and spreading

PubMed Central

Vernerey, Franck J.; Farsad, Mehdi

2013-01-01

Recent research has shown that cell spreading is highly dependent on the contractililty of its cytoskeleton and the mechanical properties of the environment it is located in. The dynamics of such process is critical for the development of tissue engineering strategy but is also a key player in wound contraction, tissue maintenance and angiogenesis. To better understand the underlying physics of such phenomena, the paper describes a mathematical formulation of cell spreading and contraction that couples the processes of stress fiber formation, protrusion growth through actin polymerization at the cell edge and dynamics of cross-membrane protein (integrins) enabling cell-substrate attachment. The evolving cell’s cytoskeleton is modeled as a mixture of fluid, proteins and filaments that can exchange mass and generate contraction. In particular, besides self-assembling into stress fibers, actin monomers able to polymerize into an actin meshwork at the cell’s boundary in order to push the membrane forward and generate protrusion. These processes are possible via the development of cell-substrate attachment complexes that arise from the mechano-sensitive equilibrium of membrane proteins, known as integrins. After deriving the governing equation driving the dynamics of cell evolution and spreading, we introduce a numerical solution based on the extended finite element method, combined with a level set formulation. Numerical simulations show that the proposed model is able to capture the dependency of cell spreading and contraction on substrate stiffness and chemistry. The very good agreement between model predictions and experimental observations suggests that mechanics plays a strong role into the coupled mechanisms of contraction, adhesion and spreading of adherent cells. PMID:23463540

Assessing altered motor unit recruitment patterns in paretic muscles of stroke survivors using surface electromyography.

PubMed

Hu, Xiaogang; Suresh, Aneesha K; Rymer, William Z; Suresh, Nina L

2015-12-01

The advancement of surface electromyogram (sEMG) recording and signal processing techniques has allowed us to characterize the recruitment properties of a substantial population of motor units (MUs) non-invasively. Here we seek to determine whether MU recruitment properties are modified in paretic muscles of hemispheric stroke survivors. Using an advanced EMG sensor array, we recorded sEMG during isometric contractions of the first dorsal interosseous muscle over a range of contraction levels, from 20% to 60% of maximum, in both paretic and contralateral muscles of stroke survivors. Using MU decomposition techniques, MU action potential amplitudes and recruitment thresholds were derived for simultaneously activated MUs in each isometric contraction. Our results show a significant disruption of recruitment organization in paretic muscles, in that the size principle describing recruitment rank order was materially distorted. MUs were recruited over a very narrow force range with increasing force output, generating a strong clustering effect, when referenced to recruitment force magnitude. Such disturbances in MU properties also correlated well with the impairment of voluntary force generation. Our findings provide direct evidence regarding MU recruitment modifications in paretic muscles of stroke survivors, and suggest that these modifications may contribute to weakness for voluntary contractions.

Actin turnover maintains actin filament homeostasis during cytokinetic ring contraction

PubMed Central

Palani, Saravanan; Sommese, Ruth; Kamnev, Anton; Hatano, Tomoyuki; Sivaramakrishnan, Sivaraj

2017-01-01

Cytokinesis in many eukaryotes involves a tension-generating actomyosin-based contractile ring. Many components of actomyosin rings turn over during contraction, although the significance of this turnover has remained enigmatic. Here, using Schizosaccharomyces japonicus, we investigate the role of turnover of actin and myosin II in its contraction. Actomyosin ring components self-organize into ∼1-µm-spaced clusters instead of undergoing full-ring contraction in the absence of continuous actin polymerization. This effect is reversed when actin filaments are stabilized. We tested the idea that the function of turnover is to ensure actin filament homeostasis in a synthetic system, in which we abolished turnover by fixing rings in cell ghosts with formaldehyde. We found that these rings contracted fully upon exogenous addition of a vertebrate myosin. We conclude that actin turnover is required to maintain actin filament homeostasis during ring contraction and that the requirement for turnover can be bypassed if homeostasis is achieved artificially. PMID:28655757

Automated processing of dynamic properties of intraventricular pressure by computer program and electronic circuit.

PubMed

Adler, D; Mahler, Y

1980-04-01

A procedure for automatic detection and digital processing of the maximum first derivative of the intraventricular pressure (dp/dtmax), time to dp/dtmax(t - dp/dt) and beat-to-beat intervals have been developed. The procedure integrates simple electronic circuits with a short program using a simple algorithm for the detection of the points of interest. The tasks of differentiating the pressure signal and detecting the onset of contraction were done by electronics, while the tasks of finding the values of dp/dtmax, t - dp/dt, beat-to-beat intervals and all computations needed were done by software. Software/hardware 'trade off' considerations and the accuracy and reliability of the system are discussed.

Funding Solar Projects at Federal Agencies: Mechanisms and Selection Criteria (Brochure)

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

Not Available

Implementing solar energy projects at federal facilities is a process. The project planning phase of the process includes determining goals, building a team, determining site feasibility and selecting the appropriate project funding tool. This fact sheet gives practical guidance to assist decision-makers with understanding and selecting the funding tool that would best address their site goals. Because project funding tools are complex, federal agencies should seek project assistance before making final decisions. High capital requirements combined with limits on federal agency energy contracts create challenges for funding solar projects. Solar developers typically require long-term contracts (15-20) years to spread outmore » the initial investment and to enable payments similar to conventional utility bill payments. In the private sector, 20-year contracts have been developed, vetted, and accepted, but the General Services Administration (GSA) contract authority (federal acquisition regulation [FAR] part 41) typically limits contract terms to 10 years. Payments on shorter-term contracts make solar economically unattractive compared with conventional generation. However, in several instances, the federal sector has utilized innovative funding tools that allow long-term contracts or has created a project package that is economically attractive within a shorter contract term.« less

Clot contraction: compression of erythrocytes into tightly packed polyhedra and redistribution of platelets and fibrin

PubMed Central

Cines, Douglas B.; Lebedeva, Tatiana; Nagaswami, Chandrasekaran; Hayes, Vincent; Massefski, Walter; Litvinov, Rustem I.; Rauova, Lubica; Lowery, Thomas J.

2014-01-01

Contraction of blood clots is necessary for hemostasis and wound healing and to restore flow past obstructive thrombi, but little is known about the structure of contracted clots or the role of erythrocytes in contraction. We found that contracted blood clots develop a remarkable structure, with a meshwork of fibrin and platelet aggregates on the exterior of the clot and a close-packed, tessellated array of compressed polyhedral erythrocytes within. The same results were obtained after initiation of clotting with various activators and also with clots from reconstituted human blood and mouse blood. Such close-packed arrays of polyhedral erythrocytes, or polyhedrocytes, were also observed in human arterial thrombi taken from patients. The mechanical nature of this shape change was confirmed by polyhedrocyte formation from the forces of centrifugation of blood without clotting. Platelets (with their cytoskeletal motility proteins) and fibrin(ogen) (as the substrate bridging platelets for contraction) are required to generate the forces necessary to segregate platelets/fibrin from erythrocytes and to compress erythrocytes into a tightly packed array. These results demonstrate how contracted clots form an impermeable barrier important for hemostasis and wound healing and help explain how fibrinolysis is greatly retarded as clots contract. PMID:24335500

Low Cost, Efficient Microcavity Plasma Ozone Generation for Water Remediation and Air Purification

DTIC Science & Technology

2012-06-01

Eliasson, and M. Hirth, “ Ozone Generation from Oxygen and Air: Discharge Physics and Reaction Mechanisms,” Ozone Sci. and Eng., vol. 10, pp. 367-378...Phase I Final Report: Low Cost, Efficient Microcavity Plasma Ozone Generation for Water Remediation and Air Purification...Contract Number: FA9550-11-C-0087 June 2012 Low Cost, Efficient Microcavity Plasma Ozone Generation for Water Remediation

13 CFR 124.510 - What percentage of work must a Participant perform on an 8(a) contract?

Code of Federal Regulations, 2010 CFR

2010-01-01

... performance of work percentage need not be met on task orders issued during the first six months of the... mean that the Participant must perform 50 percent of the applicable costs for each task order with its... costs for the combined total of all task orders issued to date at six month intervals. Example to...

Disrupting actin-myosin-actin connectivity in airway smooth muscle as a treatment for asthma?

PubMed

Lavoie, Tera L; Dowell, Maria L; Lakser, Oren J; Gerthoffer, William T; Fredberg, Jeffrey J; Seow, Chun Y; Mitchell, Richard W; Solway, Julian

2009-05-01

Breathing is known to functionally antagonize bronchoconstriction caused by airway muscle contraction. During breathing, tidal lung inflation generates force fluctuations that are transmitted to the contracted airway muscle. In vitro, experimental application of force fluctuations to contracted airway smooth muscle strips causes them to relengthen. Such force fluctuation-induced relengthening (FFIR) likely represents the mechanism by which breathing antagonizes bronchoconstriction. Thus, understanding the mechanisms that regulate FFIR of contracted airway muscle could suggest novel therapeutic interventions to increase FFIR, and so to enhance the beneficial effects of breathing in suppressing bronchoconstriction. Here we propose that the connectivity between actin filaments in contracting airway myocytes is a key determinant of FFIR, and suggest that disrupting actin-myosin-actin connectivity by interfering with actin polymerization or with myosin polymerization merits further evaluation as a potential novel approach for preventing prolonged bronchoconstriction in asthma.

The Generation of Three-Dimensional Body-Fitted Coordinate Systems for Viscous Flow Problems.

DTIC Science & Technology

1982-07-01

Geometries," NASA TM X-3206, 1975. iq p] Papers Written Under The Contract 1. "Basic Differential Models For Coordinate Generation ", Z . U. A. Warsi...8217 Ii (C) (4’) p Figure 1. Coordinate Surfaces fr. I • BASIC DIFFERENTIAL MODELS FOR COORDINATE GENERATION Z . U. A. WARSI* Department of Aerospace

Self-generating oscillating pressure exercise device

NASA Technical Reports Server (NTRS)

Watenpaugh, Donald E. (Inventor)

1994-01-01

An exercise device, especially suitable for zero gravity workouts, has a collapsible chamber which generates negative pressure on the lower portion of a body situated therein. The negative pressure is generated by virtue of leg, hand and shoulder interaction which contracts and expands the chamber about the person and by virtue of air flow regulation by valve action.

Discharge properties of motor units during steady isometric contractions performed with the dorsiflexor muscles

PubMed Central

Klass, Malgorzata; Duchateau, Jacques; Enoka, Roger M.

2012-01-01

The purpose of this study was to record the discharge characteristics of tibialis anterior motor units over a range of target forces and to import these data, along with previously reported observations, into a computational model to compare experimental and simulated measures of torque variability during isometric contractions with the dorsiflexor muscles. The discharge characteristics of 44 motor units were quantified during brief isometric contractions at torques that ranged from recruitment threshold to an average of 22 ± 14.4% maximal voluntary contraction (MVC) torque above recruitment threshold. The minimal [range: 5.8–19.8 pulses per second (pps)] and peak (range: 8.6–37.5 pps) discharge rates of motor units were positively related to the recruitment threshold torque (R2 ≥ 0.266; P < 0.001). The coefficient of variation for interspike interval at recruitment was positively associated with recruitment threshold torque (R2 = 0.443; P < 0.001) and either decreased exponentially or remained constant as target torque increased above recruitment threshold torque. The variability in the simulated torque did not differ from the experimental values once the recruitment range was set to ∼85% MVC torque, and the association between motor twitch contraction times and peak twitch torque was defined as a weak linear association (R2 = 0.096; P < 0.001). These results indicate that the steadiness of isometric contractions performed with the dorsiflexor muscle depended more on the distributions of mechanical properties than discharge properties across the population of motor units in the tibialis anterior. PMID:22442023

Discharge properties of motor units during steady isometric contractions performed with the dorsiflexor muscles.

PubMed

Jesunathadas, Mark; Klass, Malgorzata; Duchateau, Jacques; Enoka, Roger M

2012-06-01

The purpose of this study was to record the discharge characteristics of tibialis anterior motor units over a range of target forces and to import these data, along with previously reported observations, into a computational model to compare experimental and simulated measures of torque variability during isometric contractions with the dorsiflexor muscles. The discharge characteristics of 44 motor units were quantified during brief isometric contractions at torques that ranged from recruitment threshold to an average of 22 ± 14.4% maximal voluntary contraction (MVC) torque above recruitment threshold. The minimal [range: 5.8-19.8 pulses per second (pps)] and peak (range: 8.6-37.5 pps) discharge rates of motor units were positively related to the recruitment threshold torque (R(2) ≥ 0.266; P < 0.001). The coefficient of variation for interspike interval at recruitment was positively associated with recruitment threshold torque (R(2) = 0.443; P < 0.001) and either decreased exponentially or remained constant as target torque increased above recruitment threshold torque. The variability in the simulated torque did not differ from the experimental values once the recruitment range was set to ∼85% MVC torque, and the association between motor twitch contraction times and peak twitch torque was defined as a weak linear association (R(2) = 0.096; P < 0.001). These results indicate that the steadiness of isometric contractions performed with the dorsiflexor muscle depended more on the distributions of mechanical properties than discharge properties across the population of motor units in the tibialis anterior.

Fiber networks amplify active stress

PubMed Central

Ronceray, Pierre; Broedersz, Chase P.

2016-01-01

Large-scale force generation is essential for biological functions such as cell motility, embryonic development, and muscle contraction. In these processes, forces generated at the molecular level by motor proteins are transmitted by disordered fiber networks, resulting in large-scale active stresses. Although these fiber networks are well characterized macroscopically, this stress generation by microscopic active units is not well understood. Here we theoretically study force transmission in these networks. We find that collective fiber buckling in the vicinity of a local active unit results in a rectification of stress towards strongly amplified isotropic contraction. This stress amplification is reinforced by the networks’ disordered nature, but saturates for high densities of active units. Our predictions are quantitatively consistent with experiments on reconstituted tissues and actomyosin networks and shed light on the role of the network microstructure in shaping active stresses in cells and tissue. PMID:26921325

Closed Cycle Electric Discharge Laser Design Investigation

DTIC Science & Technology

1978-03-01

Report Number Assigned by Contract Monitor: NASA CR- 135408 Comments on Document: Archive, RRI, DEW Descriptors, Keywords: Closed Cycle Electric...Discharge Laser Design Investigation Carbon Dioxide Monoxide Space Airborne Heat Disposal Point Track Power Solar Generator Radiation Pages: 00100...Cataloged Date: Nov 27,1992 Contract Number: NAS 3-20100 Document Type: HC Number of Copies In Library: 000001 Record ID: 25219 Source of Document: DEW

Essays on Mathematical Optimization for Residential Demand Response in the Energy Sector

NASA Astrophysics Data System (ADS)

Palaparambil Dinesh, Lakshmi

In the electric utility industry, it could be challenging to adjust supply to match demand due to large generator ramp up times, high generation costs and insufficient in-house generation capacity. Demand response (DR) is a technique for adjusting the demand for electric power instead of the supply. Direct Load Control (DLC) is one of the ways to implement DR. DLC program participants sign up for power interruption contracts and are given financial incentives for curtailing electricity usage during peak demand time periods. This dissertation studies a DLC program for residential air conditioners using mathematical optimization models. First, we develop a model that determines what contract parameters to use in designing contracts between the provider and residential customers, when to turn which power unit on or off and how much power to cut during peak demand hours. The model uses information on customer preferences for choice of contract parameters such as DLC financial incentives and energy usage curtailment. In numerical experiments, the proposed model leads to projected cost savings of the order of 20%, compared to a current benchmark model used in practice. We also quantify the impact of factors leading to cost savings and study characteristics of customers picked by different contracts. Second, we study a DLC program in a macro economic environment using a Computable General Equilibrium (CGE) model. A CGE model is used to study the impact of external factors such as policy and technology changes on different economic sectors. Here we differentiate customers based on their preference for DLC programs by using different values for price elasticity of demand for electricity commodity. Consequently, DLC program customers could substitute demand for electricity commodity with other commodities such as transportation sector. Price elasticity of demand is calculated using a novel methodology that incorporates customer preferences for DLC contracts from the first model. The calculation of elasticity based on our methodology is useful since the prices of commodities are not only determined by aggregate demand and supply but also by customers' relative preferences for commodities. In addition to this we quantify the indirect substitution and rebound effects on sectoral activity levels, incomes and prices based on customer differences, when DLC is implemented.

Microscopic heat pulses induce contraction of cardiomyocytes without calcium transients

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

Oyama, Kotaro; Mizuno, Akari; Shintani, Seine A.

Highlights: Black-Right-Pointing-Pointer Infra-red laser beam generates microscopic heat pulses. Black-Right-Pointing-Pointer Heat pulses induce contraction of cardiomyocytes. Black-Right-Pointing-Pointer Ca{sup 2+} transients during the contraction were not detected. Black-Right-Pointing-Pointer Skinned cardiomyocytes in free Ca{sup 2+} solution also contracted. Black-Right-Pointing-Pointer Heat pulses regulated the contractions without Ca{sup 2+} dynamics. -- Abstract: It was recently demonstrated that laser irradiation can control the beating of cardiomyocytes and hearts, however, the precise mechanism remains to be clarified. Among the effects induced by laser irradiation on biological tissues, temperature change is one possible effect which can alter physiological functions. Therefore, we investigated the mechanism by which heatmore » pulses, produced by infra-red laser light under an optical microscope, induce contractions of cardiomyocytes. Here we show that microscopic heat pulses induce contraction of rat adult cardiomyocytes. The temperature increase, {Delta}T, required for inducing contraction of cardiomyocytes was dependent upon the ambient temperature; that is, {Delta}T at physiological temperature was lower than that at room temperature. Ca{sup 2+} transients, which are usually coupled to contraction, were not detected. We confirmed that the contractions of skinned cardiomyocytes were induced by the heat pulses even in free Ca{sup 2+} solution. This heat pulse-induced Ca{sup 2+}-decoupled contraction technique has the potential to stimulate heart and skeletal muscles in a manner different from the conventional electrical stimulations.« less

[A study regarding estimates of the trends in the family life cycle in Korea: 1935-1975 (author's transl)].

PubMed

Kwon, H W

1981-12-01

The concept of the family life cycle is important because it leads one away from thinking in terms of static family ideal types and towards an appreication of actual process. It concerns the hypothetically "typical" family as it progresses from marriage through childrearing, children leaving home, the "empty nest" period, and the final dissolution of the family. One underlying idea of family life cycle studies is to establish a priori phases in the structure of the family as a group which are related to the process of family formation and the phases of the life cycles of those who compose it. The purpose of this paper is to look at the relationship between family types and industrialization, and to review and update previous work done in this area, as well as to estimate and discuss trends in the family life cycle on the basis of actual data available. In this study, the WHO basic model of a nuclear family life cycle is used which consists of 6 stages: formation, extension, completed extension, contraction, completed contraction, and dissolution. Some conclusions which can be drawn follow. The median age at marriage has been increasing, and although Korean women begin their childbearing later, they completed childbirth earlier, by means of reducing the number of children and by shortening the birth interval. In 1935 and 1945, husbands appeared to die before the marriage of the last child, which means the deviation of the assumption that both are alive when the last child gets married. Recent data shows that more childfree years will be spent by couples during old age than ever before. The length of each phase of the family life cycle in Korea portrays a consistent picture. The interval from marriage to the birth of the last child decreased by about 1/2, from 14.8 years in 1935 to 7.1 years in 1975. And the period of contraction has shortened about 1/2, which is an effect of smaller number of children/family and the shorter birth interval. Korean women now enjoy a longer interval between the end of the childbearing period and the final dissolution of marriage by the death of 1 spouse. The effect of the increasing divorce rate among couples could have a more profound effect on life-cycle studies. The above results and speculations remind us of the fact that patterns of action governing the ultimate disposition of persons to marry, bear children, divorce, emerge from a complex of interacting factors. (author's)

Effect of Contract Compliance Rate to a Fourth-Generation Telehealth Program on the Risk of Hospitalization in Patients With Chronic Kidney Disease: Retrospective Cohort Study.

PubMed

Hung, Chi-Sheng; Lee, Jenkuang; Chen, Ying-Hsien; Huang, Ching-Chang; Wu, Vin-Cent; Wu, Hui-Wen; Chuang, Pao-Yu; Ho, Yi-Lwun

2018-01-24

Chronic kidney disease (CKD) is prevalent in Taiwan and it is associated with high all-cause mortality. We have shown in a previous paper that a fourth-generation telehealth program is associated with lower all-cause mortality compared to usual care with a hazard ratio of 0.866 (95% CI 0.837-0.896). This study aimed to evaluate the effect of renal function status on hospitalization among patients receiving this program and to evaluate the relationship between contract compliance rate to the program and risk of hospitalization in patients with CKD. We retrospectively analyzed 715 patients receiving the telehealth care program. Contract compliance rate was defined as the percentage of days covered by the telehealth service before hospitalization. Patients were stratified into three groups according to renal function status: (1) normal renal function, (2) CKD, or (3) end-stage renal disease (ESRD) and on maintenance dialysis. The outcome measurements were first cardiovascular and all-cause hospitalizations. The association between contract compliance rate, renal function status, and hospitalization risk was analyzed with a Cox proportional hazards model with time-dependent covariates. The median follow-up duration was 694 days (IQR 338-1163). Contract compliance rate had a triphasic relationship with cardiovascular and all-cause hospitalizations. Patients with low or very high contract compliance rates were associated with a higher risk of hospitalization. Patients with CKD or ESRD were also associated with a higher risk of hospitalization. Moreover, we observed a significant interaction between the effects of renal function status and contract compliance rate on the risk of hospitalization: patients with ESRD, who were on dialysis, had an increased risk of hospitalization at a lower contract compliance rate, compared with patients with normal renal function or CKD. Our study showed that there was a triphasic relationship between contract compliance rate to the telehealth program and risk of hospitalization. Renal function status was associated with risk of hospitalization among these patients, and there was a significant interaction with contract compliance rate. ©Chi-Sheng Hung, Jenkuang Lee, Ying-Hsien Chen, Ching-Chang Huang, Vin-Cent Wu, Hui-Wen Wu, Pao-Yu Chuang, Yi-Lwun Ho. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 24.01.2018.

Genetic dissection of quantitative trait locus for ethanol sensitivity in long- and short-sleep mice.

PubMed

Bennett, B; Carosone-Link, P; Beeson, M; Gordon, L; Phares-Zook, N; Johnson, T E

2008-08-01

Interval-specific congenic strains (ISCS) allow fine mapping of a quantitative trait locus (QTL), narrowing its confidence interval by an order of magnitude or more. In earlier work, we mapped four QTL specifying differential ethanol sensitivity, assessed by loss of righting reflex because of ethanol (LORE), in the inbred long-sleep (ILS) and inbred short-sleep (ISS) strains, accounting for approximately 50% of the genetic variance for this trait. Subsequently, we generated reciprocal congenic strains in which each full QTL interval from ILS was bred onto the ISS background and vice versa. An earlier paper reported construction and results of the ISCS on the ISS background; here, we describe this process and report results on the ILS background. We developed multiple ISCS for each Lore QTL in which the QTL interval was broken into a number of smaller intervals. For each of the four QTL regions (chromosomes 1, 2, 11 and 15), we were successful in reducing the intervals significantly. Multiple, positive strains were overlapped to generate a single, reduced interval. Subsequently, this reduced region was overlaid on previous reductions from the ISS background congenics, resulting in substantial reductions in all QTL regions by approximately 75% from the initial mapping study. Genes with sequence or expression polymorphisms in the reduced intervals are potential candidates; evidence for these is presented. Genetic background effects can be important in detection of single QTL; combining this information with the generation of congenics on both backgrounds, as described here, is a powerful approach for fine mapping QTL.

Reversing the Course of Forgetting

ERIC Educational Resources Information Center

White, K. Geoffrey; Brown, Glenn S.

2011-01-01

Forgetting functions were generated for pigeons in a delayed matching-to-sample task, in which accuracy decreased with increasing retention-interval duration. In baseline training with dark retention intervals, accuracy was high overall. Illumination of the experimental chamber by a houselight during the retention interval impaired performance…

Interval Management: Development and Implementation of an Airborne Spacing Concept

NASA Technical Reports Server (NTRS)

Barmore, Bryan E.; Penhallegon, William J.; Weitz, Lesley A.; Bone, Randall S.; Levitt, Ian; Flores Kriegsfeld, Julia A.; Arbuckle, Doug; Johnson, William C.

2016-01-01

Interval Management is a suite of ADS-B-enabled applications that allows the air traffic controller to instruct a flight crew to achieve and maintain a desired spacing relative to another aircraft. The flight crew, assisted by automation, manages the speed of their aircraft to deliver more precise inter-aircraft spacing than is otherwise possible, which increases traffic throughput at the same or higher levels of safety. Interval Management has evolved from a long history of research and is now seen as a core NextGen capability. With avionics standards recently published, completion of an Investment Analysis Readiness Decision by the FAA, and multiple flight tests planned, Interval Management will soon be part of everyday use in the National Airspace System. Second generation, Advanced Interval Management capabilities are being planned to provide a wider range of operations and improved performance and benefits. This paper briefly reviews the evolution of Interval Management and describes current development and deployment plans. It also reviews concepts under development as the next generation of applications.

ELECTRICAL LOAD ANTICIPATOR AND RECORDER

DOEpatents

Russell, J.B.; Thomas, R.J.

1961-07-25

A system is descrbied in which an indication of the prevailing energy consumption in an electrical power metering system and a projected Power demand for one demand interval is provided at selected increments of time withm the demand interval. Each watthour meter in the system is provided with an impulse generator that generates two impulses for each revolution of the meter disc. The total pulses received frorn all the meters are continuously totaled and are fed to a plurality of parallel connected gated counters. Each counter has its gate opened at different sub-time intervals during the demand interval. A multiplier is connected to each of the gated counters except the last one and each multiplier is provided with a different multiplier constant so as to provide an estimate of the power to be drawn over the entire demand interval at the end of each of the different sub-time intervals. Means are provided for recording the ontputs from the different circuits in synchronism with the actuation oi each gate circuit.

Central excitability contributes to supramaximal volitional contractions in human incomplete spinal cord injury

PubMed Central

Thompson, Christopher K; Lewek, Michael D; Jayaraman, Arun; Hornby, T George

2011-01-01

Abstract Despite greater muscle fatigue in individuals with spinal cord injury (SCI) when compared to neurologically intact subjects using neuromuscular electrical stimulation (NMES) protocols, few studies have investigated the extent of volitional fatigue in motor incomplete SCI. Using an established protocol of 20 repeated, intermittent, maximal volitional effort (MVE) contractions, we previously demonstrated that subjects with incomplete SCI unexpectedly demonstrated a 15% increase in peak knee extensor torques within the first five MVEs with minimal evidence of fatigue after 20 contraction. In the present study, we investigated potential segmental mechanisms underlying this supramaximal torque generation. Changes in twitch properties and maximum compound muscle action potentials (M-waves) were assessed prior to and following one, three and five MVEs, revealing a significant 17% increase only in maximum twitch torques after a single MVE. Despite this post-activation potentiation of the muscle, use of conventional NMES protocols to elicit repeated muscular contractions resulted in a significant decrease in evoked torque generation, suggesting limited the muscular contributions to the observed phenomenon. To evaluate potential central mechanisms underlying the augmented torques, non-linear responses to wide-pulse width (1 ms), low-intensity, variable-frequency (25–100 Hz) NMES were also tested prior to and following repeated MVEs. When variable-frequency NMES was applied following the repeated MVEs, augmented and prolonged torques were observed and accompanied by sustained quadriceps electromyographic activity often lasting >2s after stimulus termination. Such data suggest a potential contribution of elevated spinal excitability to the reserve in volitional force generation in incomplete SCI. PMID:21610138

Regional differences in actomyosin contraction shape the primary vesicles in the embryonic chicken brain

NASA Astrophysics Data System (ADS)

Filas, Benjamen A.; Oltean, Alina; Majidi, Shabnam; Bayly, Philip V.; Beebe, David C.; Taber, Larry A.

2012-12-01

In the early embryo, the brain initially forms as a relatively straight, cylindrical epithelial tube composed of neural stem cells. The brain tube then divides into three primary vesicles (forebrain, midbrain, hindbrain), as well as a series of bulges (rhombomeres) in the hindbrain. The boundaries between these subdivisions have been well studied as regions of differential gene expression, but the morphogenetic mechanisms that generate these constrictions are not well understood. Here, we show that regional variations in actomyosin-based contractility play a major role in vesicle formation in the embryonic chicken brain. In particular, boundaries did not form in brains exposed to the nonmuscle myosin II inhibitor blebbistatin, whereas increasing contractile force using calyculin or ATP deepened boundaries considerably. Tissue staining showed that contraction likely occurs at the inner part of the wall, as F-actin and phosphorylated myosin are concentrated at the apical side. However, relatively little actin and myosin was found in rhombomere boundaries. To determine the specific physical mechanisms that drive vesicle formation, we developed a finite-element model for the brain tube. Regional apical contraction was simulated in the model, with contractile anisotropy and strength estimated from contractile protein distributions and measurements of cell shapes. The model shows that a combination of circumferential contraction in the boundary regions and relatively isotropic contraction between boundaries can generate realistic morphologies for the primary vesicles. In contrast, rhombomere formation likely involves longitudinal contraction between boundaries. Further simulations suggest that these different mechanisms are dictated by regional differences in initial morphology and the need to withstand cerebrospinal fluid pressure. This study provides a new understanding of early brain morphogenesis.

An analysis of competitive bidding by providers for indigent medical care contracts.

PubMed Central

Kirkman-Liff, B L; Christianson, J B; Hillman, D G

1985-01-01

This article develops a model of behavior in bidding for indigent medical care contracts in which bidders set bid prices to maximize their expected utility, conditional on estimates of variables which affect the payoff associated with winning or losing a contract. The hypotheses generated by this model are tested empirically using data from the first round of bidding in the Arizona indigent health care experiment. The behavior of bidding organizations in Arizona is found to be consistent in most respects with the predictions of the model. Bid prices appear to have been influenced by estimated costs and by expectations concerning the potential loss from not securing a contract, the initial wealth of the bidding organization, and the expected number of competitors in the bidding process. PMID:4086301

Isolation and partial characterization of a second myotropic peptide from the hindgut of the cockroach, Leucophaea maderae.

PubMed

Holman, G M; Cook, B J

1983-01-01

Proctolin and a second myotropic peptide were extracted from the hindgut of the cockroach Leucophaea maderae with methanol-water-acetic acid (90:9:1). The two peptides were easily separated by HPLC on a mu-Bondapak-phenyl column. Like proctolin, the second peptide was heat stable and was inactivated by the exopeptidases aminopeptidase M and carboxypeptidase Y. The response of the isolated hindgut to the new peptide was distinguishable from the response to proctolin by the following features: (a) a longer interval following application (1-4 min) to reach a maximum contraction, and (b) a much larger amplitude for single phasic contractions. Like proctolin, the new peptide could cause a protracted stimulation of the hindgut for more than 2 hr.

Changes in the contractile state, fine structure and metabolism of cardiac muscle cells during the development of rigor mortis.

PubMed

Vanderwee, M A; Humphrey, S M; Gavin, J B; Armiger, L C

1981-01-01

Transmural slices from the left anterior papillary muscle of dog hearts were maintained for 120 min in a moist atmosphere at 37 degrees C. At 15-min intervals tissue samples were taken for estimation of adenosine triphosphate (ATP) and glucose-6-phosphate (G6P) and for electron microscopic examination. At the same time the deformability under standard load of comparable regions of an adjacent slice of tissue was measured. ATP levels fell rapidly during the first 45 to 75 min after excision of the heart. During a subsequent further decline in ATP, the mean deformability of myocardium fell from 30 to 12% indicating the development of rigor mortis. Conversely, G6P levels increased during the first decline in adenosine triphosphate but remained relatively steady thereafter. Whereas many of the myocardial cells fixed after 5 min contracted on contact with glutaraldehyde, all cells examined after 15 to 40 min were relaxed. A progressive increase in the proportion of contracted cells was observed during the rapid increase in myocardial rigidity. During this late contraction the cells showed morphological evidence of irreversible injury. These findings suggest that ischaemic myocytes contract just before actin and myosin become strongly linked to maintain the state of rigor mortis.

Spatial patterns of fasting and fed antropyloric pressure waves in humans.

PubMed Central

Sun, W M; Hebbard, G S; Malbert, C H; Jones, K L; Doran, S; Horowitz, M; Dent, J

1997-01-01

1. Gastric mechanics were investigated by categorizing the temporal and spatial patterning of pressure waves associated with individual gastric contractions. 2. In twelve healthy volunteers, intraluminal pressures were monitored from nine side hole recording points spaced at 1.5 cm intervals along the antrum, pylorus and duodenum. 3. Pressure wave sequences that occurred during phase II fasting contractions (n = 221) and after food (n = 778) were evaluated. 4. The most common pattern of pressure wave onset along the antrum was a variable combination of antegrade, synchronous and retrograde propagation between side hole pairs. This variable pattern accounted for 42% of sequences after food, and 34% during fasting (P < 0.05). Other common pressure wave sequence patterns were: purely antegrade-29% after food and 42% during fasting (P < 0.05); purely synchronous-23% fed and 17% fasting; and purely retrograde-6% fed and 8% fasting. The length of sequences was shorter after food (P < 0.05). Some sequences 'skipped' individual recording points. 5. The spatial patterning of gastric pressure wave sequences is diverse, and may explain the differing mechanical outcomes among individual gastric contractions. 6. Better understanding of gastric mechanics may be gained from temporally precise correlations of luminal flows and pressures and gastric wall motion during individual gastric contraction sequences. PMID:9306286

A queuing-theory-based interval-fuzzy robust two-stage programming model for environmental management under uncertainty

NASA Astrophysics Data System (ADS)

Sun, Y.; Li, Y. P.; Huang, G. H.

2012-06-01

In this study, a queuing-theory-based interval-fuzzy robust two-stage programming (QB-IRTP) model is developed through introducing queuing theory into an interval-fuzzy robust two-stage (IRTP) optimization framework. The developed QB-IRTP model can not only address highly uncertain information for the lower and upper bounds of interval parameters but also be used for analysing a variety of policy scenarios that are associated with different levels of economic penalties when the promised targets are violated. Moreover, it can reflect uncertainties in queuing theory problems. The developed method has been applied to a case of long-term municipal solid waste (MSW) management planning. Interval solutions associated with different waste-generation rates, different waiting costs and different arriving rates have been obtained. They can be used for generating decision alternatives and thus help managers to identify desired MSW management policies under various economic objectives and system reliability constraints.

Mechanisms of in vivo muscle fatigue in humans: investigating age‐related fatigue resistance with a computational model

PubMed Central

Callahan, Damien M.; Umberger, Brian R.

2016-01-01

Key points Muscle fatigue can be defined as the transient decrease in maximal force that occurs in response to muscle use. Fatigue develops because of a complex set of changes within the neuromuscular system that are difficult to evaluate simultaneously in humans.The skeletal muscle of older adults fatigues less than that of young adults during static contractions. The potential sources of this difference are multiple and intertwined.To evaluate the individual mechanisms of fatigue, we developed an integrative computational model based on neural, biochemical, morphological and physiological properties of human skeletal muscle.Our results indicate first that the model provides accurate predictions of fatigue and second that the age‐related resistance to fatigue is due largely to a lower reliance on glycolytic metabolism during contraction.This model should prove useful for generating hypotheses for future experimental studies into the mechanisms of muscle fatigue. Abstract During repeated or sustained muscle activation, force‐generating capacity becomes limited in a process referred to as fatigue. Multiple factors, including motor unit activation patterns, muscle fibre contractile properties and bioenergetic function, can impact force‐generating capacity and thus the potential to resist fatigue. Given that neuromuscular fatigue depends on interrelated factors, quantifying their independent effects on force‐generating capacity is not possible in vivo. Computational models can provide insight into complex systems in which multiple inputs determine discrete outputs. However, few computational models to date have investigated neuromuscular fatigue by incorporating the multiple levels of neuromuscular function known to impact human in vivo function. To address this limitation, we present a computational model that predicts neural activation, biomechanical forces, intracellular metabolic perturbations and, ultimately, fatigue during repeated isometric contractions. This model was compared with metabolic and contractile responses to repeated activation using values reported in the literature. Once validated in this way, the model was modified to reflect age‐related changes in neuromuscular function. Comparisons between initial and age‐modified simulations indicated that the age‐modified model predicted less fatigue during repeated isometric contractions, consistent with reports in the literature. Together, our simulations suggest that reduced glycolytic flux is the greatest contributor to the phenomenon of age‐related fatigue resistance. In contrast, oxidative resynthesis of phosphocreatine between intermittent contractions and inherent buffering capacity had minimal impact on predicted fatigue during isometric contractions. The insights gained from these simulations cannot be achieved through traditional in vivo or in vitro experimentation alone. PMID:26824934

Triplet firing origin in human motor units: emerging hypotheses.

PubMed

Kudina, Lydia P; Andreeva, Regina E

2016-03-01

A specific feature of motor unit (MU) firing behaviour is rhythmic trains of single discharges at low rate resulting from the prolonged motoneuronal afterhyperpolarization. However, some MUs exhibit occasional doublets with uniquely short interspike intervals (2.5-20.0 ms). Motoneuronal delayed depolarization is commonly accepted to be doublet underlying mechanism. Apart from doublets, much scarcer MU triple discharges were described, but their mechanisms are disputable. The aim of the present study was to analyse MU triplet firing origin in healthy humans. MU triple discharges occasionally arising during gentle voluntary muscle contractions were compared with those arising in axons during motor nerve stimulation. Firing pattern was analysed in 109 MUs of four muscles: the tibialis anterior, the flexor carpi ulnaris, the abductor pollicis brevis, and the abductor digiti minimi. Our findings present evidence that during voluntary contractions two kinds of MU triplet firing can be occasionally observed: "true" motoneuronal triplets (interspike intervals of 3.6-17.3 ms) with the delayed depolarization as the possible underlying mechanism and axonal triple discharges including the M-response and F-wave. The findings can be useful not only for understanding mechanisms of the very rare motoneuronal firing in healthy humans but also for estimation of pathological triplet firing origin.

Relationship between abdominal and pelvic floor muscle activation and intravaginal pressure during pelvic floor muscle contractions in healthy continent women.

PubMed

Madill, Stéphanie J; McLean, Linda

2006-01-01

Activation of the abdominal muscles might contribute to the generation of a strong pelvic floor muscle contraction, and consequently may contribute to the continence mechanism in women. The purpose of this study was to determine the abdominal muscle activation levels and the patterns of muscle activity associated with voluntary pelvic floor muscle (PFM) contractions in urinary continent women. Fifteen healthy continent women participated. They performed three maximal contractions of each of the four abdominal muscles and of their PFMs while in supine. Abdominal and PFM activity was recorded using electromyography (EMG), and intravaginal pressure was recorded using a custom modified Femiscan probe. During voluntary maximal PFM contractions, rectus abdominus was activated to 9.61 (+/-7.42)% maximal voluntary electrical activity (MVE), transversus abdominus was activated to 224.30(+/-47.4)% MVE, the external obliques were activated to 18.72(+/-13.33)% MVE, and the internal obliques were activated to 81.47(+/-63.57)% MVE. A clear pattern of activation emerged, whereby the transversus abdominus, internal oblique, and rectus abdominus muscles worked with the PFM in the initial generation of maximal intravaginal pressure. PFM activity predominated in the initial rise in lower vaginal pressure, with later increases in pressure (up to 70% maximum pressure) being associated with the combined activation of the PFM, rectus abdominus, internal obliques, and transverses abdominus. These abdominal muscles were the primary source of intravaginal pressure increases in the latter 30% of the task, whereas there was little increase in PFM activation from this point on. The external oblique muscles showed no clear pattern of activity, but worked at approximately 20% MVE throughout the PFM contractions, suggesting that their role may be predominantly in postural setting prior to the initiation of intravaginal pressure increases. Defined patterns of abdominal muscle activity were found in response to voluntary PFM contractions in healthy continent women. (c) 2006 Wiley-Liss, Inc.

In-vivo measurement of muscle tension: dynamic properties of the MC sensor during isometric muscle contraction.

PubMed

Đorđević, Srđan; Tomažič, Sašo; Narici, Marco; Pišot, Rado; Meglič, Andrej

2014-09-25

Skeletal muscle is the largest tissue structure in our body and plays an essential role for producing motion through integrated action with bones, tendons, ligaments and joints, for stabilizing body position, for generation of heat through cell respiration and for blood glucose disposal. A key function of skeletal muscle is force generation. Non-invasive and selective measurement of muscle contraction force in the field and in clinical settings has always been challenging. The aim of our work has been to develop a sensor that can overcome these difficulties and therefore enable measurement of muscle force during different contraction conditions. In this study, we tested the mechanical properties of a "Muscle Contraction" (MC) sensor during isometric muscle contraction in different length/tension conditions. The MC sensor is attached so that it indents the skin overlying a muscle group and detects varying degrees of tension during muscular contraction. We compared MC sensor readings over the biceps brachii (BB) muscle to dynamometric measurements of force of elbow flexion, together with recordings of surface EMG signal of BB during isometric contractions at 15° and 90° of elbow flexion. Statistical correlation between MC signal and force was very high at 15° (r = 0.976) and 90° (r = 0.966) across the complete time domain. Normalized SD or σN = σ/max(FMC) was used as a measure of linearity of MC signal and elbow flexion force in dynamic conditions. The average was 8.24% for an elbow angle of 90° and 10.01% for an elbow of angle 15°, which indicates high linearity and good dynamic properties of MC sensor signal when compared to elbow flexion force. The next step of testing MC sensor potential will be to measure tension of muscle-tendon complex in conditions when length and tension change simultaneously during human motion.

10 CFR 961.2 - Applicability.

Code of Federal Regulations, 2010 CFR

2010-01-01

... ENERGY STANDARD CONTRACT FOR DISPOSAL OF SPENT NUCLEAR FUEL AND/OR HIGH-LEVEL RADIOACTIVE WASTE General... owns or generates spent nuclear fuel or high-level radioactive waste, of domestic origin, generated in... part will commit DOE to accept title to, transport, and dispose of such spent fuel and waste. In...

The Impact of Maternal Body Mass Index and Gestational Age on the Detection of Uterine Contractions by Tocodynamometry

PubMed Central

Aina-Mumuney, A.; Hwang, K.; Sunwoo, N.; Burd, I.; Blakemore, K.

2015-01-01

Objective: To examine the impact of maternal body mass index (BMI) and gestational age (GA) on uterine contraction detection by tocodynamometry. Methods: Gravidas with preterm labor (PTL) complaints who were evaluated by tocodynamometry, discharged from Labor and Delivery triage, and subsequently readmitted for preterm delivery were studied. Forty-six patients in whom contractions were detected (group 1) were compared to 49 women in whom contractions were not detected (group 2) with respect to BMI and GA at both evaluation and delivery. Multivariable logistic regression was used to adjust for confounders. Results: Group 2 had a higher mean BMI (31.7 vs 26.1, P < .001), were more likely to be obese (57.1% vs 19.6%, P < .001), and were more likely to have been evaluated in the mid-trimester (36.7% vs 17.4%, P = .04) compared to group 1. Independent risk factors for the inability of the tocodynamometer to detect contractions were obesity (odds ratio [OR] 0.18, 95% confidence interval [CI] 0.07-0.46) and evaluation in the mid-trimester (OR 0.33, 95% CI 0.13-0.84). Conclusion: Our study provides evidence that the effectiveness of tocodynamometry diminishes with increasing maternal BMI. Efficacy of tocodynamometry is also decreased at earlier GA, most pronounced below 25 weeks. To evaluate women with PTL symptoms in the mid-trimester or symptomatic obese women at any GA, a modality other than tocodynamometry could be valuable to more accurately assess uterine activity. PMID:26499394

Effects of postural and voluntary muscle contraction on modulation of the soleus H reflex by transcranial magnetic stimulation.

PubMed

Guzmán-López, Jessica; Selvi, Aikaterini; Solà-Valls, Núria; Casanova-Molla, Jordi; Valls-Solé, Josep

2015-12-01

Modulation of spinal reflexes depends largely on the integrity of the corticospinal tract. A useful method to document the influence of descending tracts on reflexes is to examine the effects of transcranial magnetic stimulation (TMS) on the soleus H reflex elicited by posterior tibial nerve electrical stimuli (PTS). In 12 healthy volunteers, we investigated how postural or voluntary muscle contraction modified such descending modulation. We first characterized the effects of TMS at 95 % of motor threshold for leg responses on the H reflex elicited by a preceding PTS at inter-stimuli intervals (ISIs) between 0 and 120 ms at rest and, then, during voluntary plantar flexion (pf), dorsal flexion (df), and standing still (ss). During pf, there was an increase in the facilitation of the H reflex at ISIs 0-20 ms. During df, there were no effects of TMS on the H reflex. During ss, there was inhibition at ISIs 40-60 ms. Our observations suggest that muscle contraction prevails over the baseline effects of TMS on the soleus H reflex. While contraction of the antagonist (df) suppressed most of the effects, contraction of the agonist had different effects depending on the type of activity (pf or ss). The characterization of the interaction between descending corticospinal volleys and segmental peripheral inputs provides useful information on motor control for physiological research and further understanding of the effects of spinal cord lesions.

Screening of cardiomyocyte fluorescence during cell contraction by multi-dimensional TCSPC

NASA Astrophysics Data System (ADS)

Chorvat, D., Jr.; Abdulla, S.; Elzwiei, F.; Mateasik, A.; Chorvatova, A.

2008-02-01

Autofluorescence is one of the most versatile non-invasive tools for mapping the metabolic state of living tissues, such as the heart. We present a new approach to the investigation of changes in endogenous fluorescence during cardiomyocyte contraction - by spectrally-resolved, time correlated, single photon counting (TCSPC). Cell contraction is stimulated by external platinum electrodes, incorporated in a home-made bath and triggered by a pulse generator at a frequency of 0.5 Hz (to stabilize sarcoplasmic reticulum loading), or 5 Hz (the rat heart rate). Cell illumination by the laser is synchronized with cell contraction, using TTL logic pulses operated by a stimulator and delayed to study mitochondrial metabolism at maximum contraction (10-110 ms) and/or at steady state (1000-1100 ms at 0.5 Hz). To test the setup, we recorded calcium transients in cells loaded with the Fluo-3 fluorescent probe (excited by 475 nm pulsed picosecond diode laser). We then evaluated recordings of flavin AF (excited by 438 nm pulsed laser) at room and physiological temperatures. Application of the presented approach will shed new insight into metabolic changes in living, contracting myocytes and, therefore, regulation of excitation-contraction coupling and/or ionic homeostasis and, thus, heart excitability.

PROBABILISTIC PROGRAMMING FOR ADVANCED MACHINE LEARNING (PPAML) DISCRIMINATIVE LEARNING FOR GENERATIVE TASKS (DILIGENT)

DTIC Science & Technology

2017-11-29

Structural connections of the frames (fragments) in the knowledge. We call the fundamental elements of the knowledge a limited number of elements...the result of contracted fundamental research deemed exempt from public affairs security and policy review in accordance with SAF/AQR memorandum dated...AVAILABILITY STATEMENT Approved for Public Release; Distribution Unlimited. This report is the result of contracted fundamental research deemed exempt from

Ethics: A Theory of Medical Ethics.

PubMed

Brody, Howard

This book review characterizes Robert Veatch's A Theory of Medical Ethics as a "third-generation" treatise that looks beyond case- and issue-oriented analysis to develop the theoretical bases of a "true system of medical ethics." Veatch proposes a "draft medical ethical covenant" based on a "triple contract" model, in which the moral principles of contract keeping, autonomy, honesty, avoiding killing, and justice govern the physician's relationship to both individual patients and society.

Redox Abnormalities as a Vulnerability Phenotype for Autism and Related Alterations in CNS Development

DTIC Science & Technology

2011-10-01

the hypothesis that SJL mice would have impaired neuronal dendrite generation, as has been observed in autism . This was our prediction due to the...phenotype for Autism and related alterations in CNS development PRINCIPAL INVESTIGATOR: Mark D. Noble, Ph.D. CONTRACTING...SUBTITLE Redox abnormalities as a vulnerability phenotype for Autism 5a. CONTRACT NUMBER And related alterations in CNS development 5b. GRANT

A Comparison of Intrathecal and Epidural Analgesia and Its Effect on Length of Labor

DTIC Science & Technology

1997-09-10

time of delivery (Chestnut, Vandewalker, Owen, Bates, & Choi, 1987 ). Epidural or intiathecal injection of opioids has the potential to provide selective...exists pertaining to this issue (Miller, DeVore, & Eisler , 1993). Selective opioid analgesia whether epidural or intrathecal has also resulted in...of contraction of the utems and the pressure generated by these contractions (Miller, DeVore, & Eisler , 1993). Progress of labor: Increasing

Influence of vision on masticatory muscles function: surface electromyographic evaluation

PubMed Central

Ciavarella, Domenico; Palazzo, Antonio; De Lillo, Alfredo; Lo Russo, Lucio; Paduano, Sergio; Laino, Luigi; Chimenti, Claudio; Frezza, Federica; Lo Muzio, Lorenzo

2014-01-01

Summary The role of the ocular disorders (OD) in pathogenesis of MMp is still a controversal issue. Ocular arc reflexes (OAR) may involve changes in head and neck posture and generate modifications of contraction resulting in muscle contraction and finally weakness. sEMG tests were performed on 28 patients (13 with masticatory muscles pain and myopia/15 healthy) in rest position with eyes open and eyes closed. Patients group control (healthy patients) showed no significance difference in sEMG record in open/close test. In non healthy patients there were great differences between the sEMG recordings with eyes closed and open. Temporalis and masseters showed a statistical difference of means activation in two tests (temporalis p = 0.0010; masseters = 0.0006). Great difference there was in means muscles activation between open eyes healthy test and non healthy. No difference in close eyes test was evaluated in temporalis and masseters close test in the two groups. The exact causes of MMp are still unknown. The role how ocular disorders (OD) may play an important role in pathogenesis of MMp is still a controversal issue. Ocular arc reflexes (OAR) may involve changes in head and neck posture and generate modifications of contraction resulting in muscle contraction and finally weakness. PMID:25002919

Assessing altered motor unit recruitment patterns in paretic muscles of stroke survivors using surface electromyography

NASA Astrophysics Data System (ADS)

Hu, Xiaogang; Suresh, Aneesha K.; Rymer, William Z.; Suresh, Nina L.

2015-12-01

Objective. The advancement of surface electromyogram (sEMG) recording and signal processing techniques has allowed us to characterize the recruitment properties of a substantial population of motor units (MUs) non-invasively. Here we seek to determine whether MU recruitment properties are modified in paretic muscles of hemispheric stroke survivors. Approach. Using an advanced EMG sensor array, we recorded sEMG during isometric contractions of the first dorsal interosseous muscle over a range of contraction levels, from 20% to 60% of maximum, in both paretic and contralateral muscles of stroke survivors. Using MU decomposition techniques, MU action potential amplitudes and recruitment thresholds were derived for simultaneously activated MUs in each isometric contraction. Main results. Our results show a significant disruption of recruitment organization in paretic muscles, in that the size principle describing recruitment rank order was materially distorted. MUs were recruited over a very narrow force range with increasing force output, generating a strong clustering effect, when referenced to recruitment force magnitude. Such disturbances in MU properties also correlated well with the impairment of voluntary force generation. Significance. Our findings provide direct evidence regarding MU recruitment modifications in paretic muscles of stroke survivors, and suggest that these modifications may contribute to weakness for voluntary contractions.

Assessing altered motor unit recruitment patterns in paretic muscles of stroke survivors using surface electromyography

PubMed Central

Hu, Xiaogang; Suresh, Aneesha K; Rymer, William Z; Suresh, Nina L

2017-01-01

Objective The advancement of surface electromyogram (sEMG) recording and signal processing techniques has allowed us to characterize the recruitment properties of a substantial population of motor units (MUs) non-invasively. Here we seek to determine whether MU recruitment properties are modified in paretic muscles of hemispheric stroke survivors. Approach Using an advanced EMG sensor array, we recorded sEMG during isometric contractions of the first dorsal interosseous muscle over a range of contraction levels, from 20% to 60% of maximum, in both paretic and contralateral muscles of stroke survivors. Using MU decomposition techniques, MU action potential amplitudes and recruitment thresholds were derived for simultaneously activated MUs in each isometric contraction. Main results Our results show a significant disruption of recruitment organization in paretic muscles, in that the size principle describing recruitment rank order was materially distorted. MUs were recruited over a very narrow force range with increasing force output, generating a strong clustering effect, when referenced to recruitment force magnitude. Such disturbances in MU properties also correlated well with the impairment of voluntary force generation. Significance Our findings provide direct evidence regarding MU recruitment modifications in paretic muscles of stroke survivors, and suggest that these modifications may contribute to weakness for voluntary contractions. PMID:26402920

Mitotic cells contract actomyosin cortex and generate pressure to round against or escape epithelial confinement

PubMed Central

Sorce, Barbara; Escobedo, Carlos; Toyoda, Yusuke; Stewart, Martin P.; Cattin, Cedric J.; Newton, Richard; Banerjee, Indranil; Stettler, Alexander; Roska, Botond; Eaton, Suzanne; Hyman, Anthony A.; Hierlemann, Andreas; Müller, Daniel J.

2015-01-01

Little is known about how mitotic cells round against epithelial confinement. Here, we engineer micropillar arrays that subject cells to lateral mechanical confinement similar to that experienced in epithelia. If generating sufficient force to deform the pillars, rounding epithelial (MDCK) cells can create space to divide. However, if mitotic cells cannot create sufficient space, their rounding force, which is generated by actomyosin contraction and hydrostatic pressure, pushes the cell out of confinement. After conducting mitosis in an unperturbed manner, both daughter cells return to the confinement of the pillars. Cells that cannot round against nor escape confinement cannot orient their mitotic spindles and more likely undergo apoptosis. The results highlight how spatially constrained epithelial cells prepare for mitosis: either they are strong enough to round up or they must escape. The ability to escape from confinement and reintegrate after mitosis appears to be a basic property of epithelial cells. PMID:26602832

Mitotic cells contract actomyosin cortex and generate pressure to round against or escape epithelial confinement

NASA Astrophysics Data System (ADS)

Sorce, Barbara; Escobedo, Carlos; Toyoda, Yusuke; Stewart, Martin P.; Cattin, Cedric J.; Newton, Richard; Banerjee, Indranil; Stettler, Alexander; Roska, Botond; Eaton, Suzanne; Hyman, Anthony A.; Hierlemann, Andreas; Müller, Daniel J.

2015-11-01

Little is known about how mitotic cells round against epithelial confinement. Here, we engineer micropillar arrays that subject cells to lateral mechanical confinement similar to that experienced in epithelia. If generating sufficient force to deform the pillars, rounding epithelial (MDCK) cells can create space to divide. However, if mitotic cells cannot create sufficient space, their rounding force, which is generated by actomyosin contraction and hydrostatic pressure, pushes the cell out of confinement. After conducting mitosis in an unperturbed manner, both daughter cells return to the confinement of the pillars. Cells that cannot round against nor escape confinement cannot orient their mitotic spindles and more likely undergo apoptosis. The results highlight how spatially constrained epithelial cells prepare for mitosis: either they are strong enough to round up or they must escape. The ability to escape from confinement and reintegrate after mitosis appears to be a basic property of epithelial cells.

Study on Stochastic Optimal Electric Power Procurement Strategies with Uncertain Market Prices

NASA Astrophysics Data System (ADS)

Sakchai, Siripatanakulkhajorn; Saisho, Yuichi; Fujii, Yasumasa; Yamaji, Kenji

The player in deregulated electricity markets can be categorized into three groups of GENCO (Generator Companies), TRNASCO (Transmission Companies), DISCO (Distribution Companies). This research focuses on the role of Distribution Companies, which purchase electricity from market at randomly fluctuating prices, and provide it to their customers at given fixed prices. Therefore Distribution companies have to take the risk stemming from price fluctuation of electricity instead of the customers. This entails the necessity to develop a certain method to make an optimal strategy for electricity procurement. In such a circumstance, this research has the purpose for proposing the mathematical method based on stochastic dynamic programming to evaluate the value of a long-term bilateral contract of electricity trade, and also a project of combination of the bilateral contract and power generation with their own generators for procuring electric power in deregulated market.

The relationship of motor unit size, firing rate and force.

PubMed

Conwit, R A; Stashuk, D; Tracy, B; McHugh, M; Brown, W F; Metter, E J

1999-07-01

Using a clinical electromyographic (EMG) protocol, motor units were sampled from the quadriceps femoris during isometric contractions at fixed force levels to examine how average motor unit size and firing rate relate to force generation. Mean firing rates (mFRs) and sizes (mean surface-detected motor unit action potential (mS-MUAP) area) of samples of active motor units were assessed at various force levels in 79 subjects. MS-MUAP size increased linearly with increased force generation, while mFR remained relatively constant up to 30% of a maximal force and increased appreciably only at higher force levels. A relationship was found between muscle force and mS-MUAP area (r2 = 0.67), mFR (r2 = 0.38), and the product of mS-MUAP area and mFR (mS-MUAP x mFR) (r2 = 0.70). The results support the hypothesis that motor units are recruited in an orderly manner during forceful contractions, and that in large muscles only at higher levels of contraction ( > 30% MVC) do mFRs increase appreciably. MS-MUAP and mFR can be assessed using clinical EMG techniques and they may provide a physiological basis for analyzing the role of motor units during muscle force generation.

Detection of Atrial Fibrillation Using Artifical Neural Network with Power Spectrum Density of RR Interval of Electrocardiogram

NASA Astrophysics Data System (ADS)

Afdala, Adfal; Nuryani, Nuryani; Satrio Nugroho, Anto

2017-01-01

Atrial fibrillation (AF) is a disorder of the heart with fairly high mortality in adults. AF is a common heart arrythmia which is characterized by a missing or irregular contraction of atria. Therefore, finding a method to detect atrial fibrillation is necessary. In this article a system to detect atrial fibrillation has been proposed. Detection system utilized backpropagation artifical neural network. Data input in this method includes power spectrum density of R-peaks interval of electrocardiogram which is selected by wrapping method. This research uses parameter learning rate, momentum, epoch and hidden layer. System produces good performance with accuracy, sensitivity, and specificity of 83.55%, 86.72 % and 81.47 %, respectively.

Compensatory strategies during walking in response to excessive muscle co-contraction at the ankle joint.

PubMed

Wang, Ruoli; Gutierrez-Farewik, Elena M

2014-03-01

Excessive co-contraction causes inefficient or abnormal movement in several neuromuscular pathologies. How synergistic muscles spanning the ankle, knee and hip adapt to co-contraction of ankle muscles is not well understood. This study aimed to identify the compensation strategies required to retain normal walking with excessive antagonistic ankle muscle co-contraction. Muscle-actuated simulations of normal walking were performed to quantify compensatory mechanisms of ankle and knee muscles during stance in the presence of normal, medium and high levels of co-contraction of antagonistic pairs gastrocnemius+tibialis anterior and soleus+tibialis anterior. The study showed that if co-contraction increases, the synergistic ankle muscles can compensate; with gastrocmemius+tibialis anterior co-contraction, the soleus will increase its contribution to ankle plantarflexion acceleration. At the knee, however, almost all muscles spanning the knee and hip are involved in compensation. We also found that ankle and knee muscles alone can provide sufficient compensation at the ankle joint, but hip muscles must be involved to generate sufficient knee moment. Our findings imply that subjects with a rather high level of dorsiflexor+plantarflexor co-contraction can still perform normal walking. This also suggests that capacity of other lower limb muscles to compensate is important to retain normal walking in co-contracted persons. The compensatory mechanisms can be useful in clinical interpretation of motion analyses, when secondary muscle co-contraction or other deficits may present simultaneously in subjects with motion disorders. Copyright © 2014 Elsevier B.V. All rights reserved.

Dynamic aspects of the contractile system in Physarum plasmodium. III. Cyclic contraction-relaxation of the plasmodial fragment in accordance with the generation-degeneration of cytoplasmic actomyosin fibrils

PubMed Central

1987-01-01

Plasmodial fragments of Physarum polycephalum, excised from anterior regions of a thin-spread plasmodium, contracted-relaxed cyclicly with a period of 3-5 min. The area of the fragments decreased approximately 10% during contraction. In most cases, there was little endoplasmic streaming which indicates that contractions were synchronized throughout the fragment. By both polarized light and fluorescence microscopy, the organization and distribution of the cytoplasmic actomyosin fibrils in the fragments changed in synchrony with the contraction cycle. The fibrils formed during the contraction phase, and finally became a highly organized framework consisting of a three- dimensional network of numerous fibrils with many converging points (the nodes). During relaxation, the fibrils degenerated and disappeared almost completely, though some very weak fibrils remained near the nodes and the periphery. The results obtained by fluorometry of the fragments, stained with rhodamine-phalloidin, suggested that the G-F transformation of actin is not the main underlying process of the fibrillar formation. PMID:3611192

Selective Effects of Baclofen on Use-Dependent Modulation of GABAB Inhibition after Tetraplegia

PubMed Central

Barry, Melissa D.; Bunday, Karen L.; Chen, Robert

2013-01-01

Baclofen is a GABAB receptor agonist commonly used to relief spasticity related to motor disorders. The effects of baclofen on voluntary motor output are limited and not yet understood. Using noninvasive transcranial magnetic and electrical stimulation techniques, we examined electrophysiological measures probably involving GABAB (long-interval intracortical inhibition and the cortical silent period) and GABAA (short-interval intracortical inhibition) receptors, which are inhibitory effects mediated by subcortical and cortical mechanisms. We demonstrate increased active long-interval intracortical inhibition and prolonged cortical silent period during voluntary activity of an intrinsic finger muscle in humans with chronic incomplete cervical spinal cord injury (SCI) compared with age-matched controls, whereas resting long-interval intracortical inhibition was unchanged. However, long-term (∼6 years) use of baclofen decreased active long-interval intracortical inhibition to similar levels as controls but did not affect the duration of the cortical silent period. We found a correlation between signs of spasticity and long-interval intracortical inhibition in patients with SCI. Short-interval intracortical inhibition was decreased during voluntary contraction compared with rest but there was no effect of SCI or baclofen use. Together, these results demonstrate that baclofen selectively maintains use-dependent modulation of largely subcortical but not cortical GABAB neuronal pathways after human SCI. Thus, cortical GABAB circuits may be less sensitive to baclofen than spinal GABAB circuits. This may contribute to the limited effects of baclofen on voluntary motor output in subjects with motor disorders affected by spasticity. PMID:23904624

Bootstrapping Confidence Intervals for Robust Measures of Association.

ERIC Educational Resources Information Center

King, Jason E.

A Monte Carlo simulation study was conducted to determine the bootstrap correction formula yielding the most accurate confidence intervals for robust measures of association. Confidence intervals were generated via the percentile, adjusted, BC, and BC(a) bootstrap procedures and applied to the Winsorized, percentage bend, and Pearson correlation…

A smooth muscle tone-dependent stretch-activated migrating motor pattern in isolated guinea-pig distal colon.

PubMed

Smith, Terence K; Oliver, Gavin R; Hennig, Grant W; O'Shea, Deirdre M; Vanden Berghe, Pieter; Kang, Sok Han; Spencer, Nick J

2003-09-15

We have investigated the tone dependence of the intrinsic nervous activity generated by localized wall distension in isolated segments of guinea-pig distal colon using mechanical recordings and video imaging of wall movements. A segment of colon was threaded through two partitions, which divided the colon for pharmacological purposes into oral, stimulation and anal regions. An intraluminal balloon was located in the stimulation region between the two partitions (12 mm apart). Maintained colonic distension by an intraluminal balloon or an artificial faecal pellet held at a fixed location generated rhythmic (frequency 0.3 contractions min(-1); duration approximately 60 s) peristaltic waves of contraction. Video imaging of colonic wall movements or the selective application of pharmacological agents suggested that peristaltic waves originated just oral (< or = 4 mm) to the pellet and propagated both orally (approximately 11 mm s(-1)) and anally (approximately 1 mm s(-1)). Also, during a peristaltic wave the colon appears to passively shorten in front of a pellet, as a result of an active contraction of the longitudinal muscle oral to the pellet. Faecal pellet movement only occurred when a rhythmic peristaltic wave was generated. Rhythmic peristaltic waves were abolished in all regions by the smooth muscle relaxants isoproterenol (1 microM), nicardipine (1 microM) or papavarine (10 microM), and by the neural antagonists tetrodotoxin (TTX; 0.6 microM), hexamethonium (100 microM) or atropine (1 microM), when added selectively to the stimulation region. Nicardipine, atropine, TTX, or hexamethonium (100 microM) also blocked the evoked peristaltic waves when selectively added to the oral region. Nomega-nitro-L-arginine (L-NA; 100 microM) added to the anal region reduced the anal relaxation but increased the anal contraction, leading to an increase in the apparent conduction velocity of each peristaltic wave. In conclusion, maintained distension by a fixed artificial pellet generates propulsive, rhythmic peristaltic waves, whose enteric neural activity is critically dependent upon smooth muscle tone. These peristaltic waves usually originate just oral to the pellet, and their apparent conduction velocity is generated by activation of descending inhibitory nerve pathways.

Essays in renewable energy and emissions trading

NASA Astrophysics Data System (ADS)

Kneifel, Joshua D.

Environmental issues have become a key political issue over the past forty years and has resulted in the enactment of many different environmental policies. The three essays in this dissertation add to the literature of renewable energy policies and sulfur dioxide emissions trading. The first essay ascertains which state policies are accelerating deployment of non-hydropower renewable electricity generation capacity into a states electric power industry. As would be expected, policies that lead to significant increases in actual renewable capacity in that state either set a Renewables Portfolio Standard with a certain level of required renewable capacity or use Clean Energy Funds to directly fund utility-scale renewable capacity construction. A surprising result is that Required Green Power Options, a policy that merely requires all utilities in a state to offer the option for consumers to purchase renewable energy at a premium rate, has a sizable impact on non-hydro renewable capacity in that state. The second essay studies the theoretical impacts fuel contract constraints have on an electricity generating unit's compliance costs of meeting the emissions compliance restrictions set by Phase I of the Title IV SO2 Emissions Trading Program. Fuel contract constraints restrict a utility's degrees of freedom in coal purchasing options, which can lead to the use of a more expensive compliance option and higher compliance costs. The third essay analytically and empirically shows how fuel contract constraints impact the emissions allowance market and total electric power industry compliance costs. This paper uses generating unit-level simulations to replicate results from previous studies and show that fuel contracts appear to explain a large portion (65%) of the previously unexplained compliance cost simulations. Also, my study considers a more appropriate plant-level decisions for compliance choices by analytically analyzing the plant level decision-making process to show how cost-minimization at the more complex plant level may deviate from cost-minimization at the generating unit level.

75 FR 5120 - United States, et al. v. Stericycle, Inc., et al.; Proposed Final Judgment and Competitive Impact...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-01

... services for Large Quantity Generator (``LQG'') customers in the states of Kansas, Missouri, Nebraska, and...; Oklahoma City, Oklahoma; Omaha, Nebraska; and Booneville, Missouri; LQG customer contracts associated with... collection and treatment services for large quantity generator (``LQG'') customers. The resulting combination...

30 CFR 1206.354 - How do I determine generating deductions?

Code of Federal Regulations, 2011 CFR

2011-07-01

... electricity from the plant tailgate value of the electricity (usually the transmission-reduced value of the...'s-length power plant contract. (b)(1) You must base your generating costs deduction on your actual annual costs associated with the construction and operation of a geothermal power plant. (i) You must...

78 FR 27178 - Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-09

... Generation and Transmission cooperatives (G&T's) that generate or purchase power and transmit the power to the distribution systems. All RUS and G&T borrowers will enter into a Wholesale Power Contract with... the credit quality and credit worthiness of loans and loan guarantees to G&T borrowers. RUS works...

A Variable Oscillator Underlies the Measurement of Time Intervals in the Rostral Medial Prefrontal Cortex during Classical Eyeblink Conditioning in Rabbits.

PubMed

Caro-Martín, C Rocío; Leal-Campanario, Rocío; Sánchez-Campusano, Raudel; Delgado-García, José M; Gruart, Agnès

2015-11-04

We were interested in determining whether rostral medial prefrontal cortex (rmPFC) neurons participate in the measurement of conditioned stimulus-unconditioned stimulus (CS-US) time intervals during classical eyeblink conditioning. Rabbits were conditioned with a delay paradigm consisting of a tone as CS. The CS started 50, 250, 500, 1000, or 2000 ms before and coterminated with an air puff (100 ms) directed at the cornea as the US. Eyelid movements were recorded with the magnetic search coil technique and the EMG activity of the orbicularis oculi muscle. Firing activities of rmPFC neurons were recorded across conditioning sessions. Reflex and conditioned eyelid responses presented a dominant oscillatory frequency of ≈12 Hz. The firing rate of each recorded neuron presented a single peak of activity with a frequency dependent on the CS-US interval (i.e., ≈12 Hz for 250 ms, ≈6 Hz for 500 ms, and≈3 Hz for 1000 ms). Interestingly, rmPFC neurons presented their dominant firing peaks at three precise times evenly distributed with respect to CS start and also depending on the duration of the CS-US interval (only for intervals of 250, 500, and 1000 ms). No significant neural responses were recorded at very short (50 ms) or long (2000 ms) CS-US intervals. rmPFC neurons seem not to encode the oscillatory properties characterizing conditioned eyelid responses in rabbits, but are probably involved in the determination of CS-US intervals of an intermediate range (250-1000 ms). We propose that a variable oscillator underlies the generation of working memories in rabbits. The way in which brains generate working memories (those used for the transient processing and storage of newly acquired information) is still an intriguing question. Here, we report that the firing activities of neurons located in the rostromedial prefrontal cortex recorded in alert behaving rabbits are controlled by a dynamic oscillator. This oscillator generated firing frequencies in a variable band of 3-12 Hz depending on the conditioned stimulus-unconditioned stimulus intervals (1 s, 500 ms, 250 ms) selected for classical eyeblink conditioning of behaving rabbits. Shorter (50 ms) and longer (2 s) intervals failed to activate the oscillator and prevented the acquisition of conditioned eyelid responses. This is an unexpected mechanism to generate sustained firing activities in neural circuits generating working memories. Copyright © 2015 the authors 0270-6474/15/3514809-13$15.00/0.

Variability in common synaptic input to motor neurons modulates both force steadiness and pegboard time in young and older adults.

PubMed

Feeney, Daniel F; Mani, Diba; Enoka, Roger M

2018-06-07

We investigated the associations between grooved pegboard times, force steadiness (coefficient of variation for force), and variability in an estimate of the common synaptic input to motor neurons innervating the wrist extensor muscles during steady contractions performed by young and older adults. The discharge times of motor units were derived from recordings obtained with high-density surface electrodes while participants performed steady isometric contractions at 10% and 20% of maximal voluntary contraction (MVC) force. The steady contractions were performed with a pinch grip and wrist extension, both independently (single action) and concurrently (double action). The variance in common synaptic input to motor neurons was estimated with a state-space model of the latent common input dynamics. There was a statistically significant association between the coefficient of variation for force during the steady contractions and the estimated variance in common synaptic input in young (r 2 = 0.31) and older (r 2 = 0.39) adults, but not between either the mean or the coefficient of variation for interspike interval of single motor units with the coefficient of variation for force. Moreover, the estimated variance in common synaptic input during the double-action task with the wrist extensors at the 20% target was significantly associated with grooved pegboard time (r 2 = 0.47) for older adults, but not young adults. These findings indicate that longer pegboard times of older adults were associated with worse force steadiness and greater fluctuations in the estimated common synaptic input to motor neurons during steady contractions. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Postprandial gastric antral contractions in patients with gastro-oesophageal reflux disease: a scintigraphic study.

PubMed

Barbieri, C L A; Troncon, L E A; Herculano, J R L; Aprile, L R O; Moraes, E R; Secaf, M; Dantas, R O

2008-05-01

Disturbed gastric contractility has been found in manometric studies in patients with gastro-oesophageal reflux disease (GORD), but the pathophysiological role of this abnormality is unclear. We aimed at assessing postprandial gastric antral contractions and its relationships with gastric emptying and gastro-oesophageal reflux in GORD patients. Fasted GORD patients (n = 13) and healthy volunteers (n = 13) ingested a liquid meal labelled with 72 MBq of 99mTechnetium-phytate. Gastric images were acquired every 10 min for 2 h, for measuring gastric emptying half time. Dynamic antral scintigraphy (one frame per second), performed for 4 min at 30-min intervals, allowed estimation of both mean dominant frequency and amplitude of antral contractions. In GORD patients (n = 10), acidic reflux episodes occurring 2 h after the ingestion of the same test meal were determined by ambulatory 24-h oesophageal pH monitoring. Gastric emptying was similar in GORD patients and controls (median; range: 82 min; 58-126 vs 80 min; 44-122 min; P = 0.38). Frequency of antral contractions was also similar in both groups (3.1 cpm; 2.8-3.6 vs 3.2 cpm; 2.4-3.8 cpm; P = 0.15). In GORD patients, amplitude of antral contractions was significantly higher than in controls (32.7%; 17-44%vs 23.3%; 16-43%; P = 0.01), and correlated positively with gastric emptying time (R(s) = 0.58; P = 0.03) and inversely with the number of reflux episodes (R(s) = -0.68; P = 0.02). Increased amplitude of postprandial gastric antral contractions in GORD may comprise a compensatory mechanism against delayed gastric emptying and a defensive factor against acidic gastro-oesophageal reflux.

Loss of knee extensor torque complexity during fatiguing isometric muscle contractions occurs exclusively above the critical torque.

PubMed

Pethick, Jamie; Winter, Samantha L; Burnley, Mark

2016-06-01

The complexity of knee extensor torque time series decreases during fatiguing isometric muscle contractions. We hypothesized that because of peripheral fatigue, this loss of torque complexity would occur exclusively during contractions above the critical torque (CT). Nine healthy participants performed isometric knee extension exercise (6 s of contraction, 4 s of rest) on six occasions for 30 min or to task failure, whichever occurred sooner. Four trials were performed above CT (trials S1-S4, S1 being the lowest intensity), and two were performed below CT (at 50% and 90% of CT). Global, central, and peripheral fatigue were quantified using maximal voluntary contractions (MVCs) with femoral nerve stimulation. The complexity of torque output was determined using approximate entropy (ApEn) and the detrended fluctuation analysis-α scaling exponent (DFA-α). The MVC torque was reduced in trials below CT [by 19 ± 4% (means ± SE) in 90%CT], but complexity did not decrease [ApEn for 90%CT: from 0.82 ± 0.03 to 0.75 ± 0.06, 95% paired-samples confidence intervals (CIs), 95% CI = -0.23, 0.10; DFA-α from 1.36 ± 0.01 to 1.32 ± 0.03, 95% CI -0.12, 0.04]. Above CT, substantial reductions in MVC torque occurred (of 49 ± 8% in S1), and torque complexity was reduced (ApEn for S1: from 0.67 ± 0.06 to 0.14 ± 0.01, 95% CI = -0.72, -0.33; DFA-α from 1.38 ± 0.03 to 1.58 ± 0.01, 95% CI 0.12, 0.29). Thus, in these experiments, the fatigue-induced loss of torque complexity occurred exclusively during contractions performed above the CT. Copyright © 2016 the American Physiological Society.

Modeling the Formation of Hydrate-Filled Veins in Fine-Grained Sediments from in Situ Microbial Methane

NASA Astrophysics Data System (ADS)

Malinverno, A.; Cook, A.; Daigle, H.

2016-12-01

Continental margin sediments are dominantly fine-grained silt and clay, and methane hydrates in these sediments are often found in semi-vertical veins and fractures. In several instances, these hydrate veins occupy discrete depth intervals that are a few tens of meters thick and are surrounded by hydrate-free sediments. As they are not connected with gas sources beneath the base of the gas hydrate stability zone (GHSZ), these isolated hydrate-bearing intervals have been interpreted as formed by in situ microbial methane. To investigate the formation of these hydrate deposits, we applied a time-dependent advection-diffusion-reaction model that includes the effects of sedimentation, compaction, solute diffusion, and microbial methane generation. Microbial methane generation depends on the amount of metabolizable organic carbon deposited at the seafloor, whose progressive degradation produces methane beneath the sulfate reduction zone. If the amount of organic carbon entering the methanogenic zone is kept constant in time, we found that the computed amounts of hydrate formed in discrete intervals within the GHSZ are well below those estimated from observations. On the other hand, if the deposition of organic carbon is higher in a given time interval, methane generation during burial is more intense in the corresponding sediment interval, resulting in enhanced hydrate formation. With variations in organic carbon deposition comparable to those generally observed in continental margins, our model was able to reproduce the methane hydrate contents that were estimated from drilling. These results support the suggestion that in situ microbial generation associated with transient organic carbon deposition is the source of methane that forms isolated intervals of hydrate-filled veins in fine-grained sediments.

Modeling the Formation of Hydrate-Filled Veins in Fine-Grained Sediments from in Situ Microbial Methane

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

Malinverno, Alberto; Cook, Ann; Daigle, Hugh

Continental margin sediments are dominantly fine-grained silt and clay, and methane hydrates in these sediments are often found in semi-vertical veins and fractures. In several instances, these hydrate veins occupy discrete depth intervals that are a few tens of meters thick and are surrounded by hydrate-free sediments. As they are not connected with gas sources beneath the base of the gas hydrate stability zone (GHSZ), these isolated hydrate-bearing intervals have been interpreted as formed by in situ microbial methane. To investigate the formation of these hydrate deposits, we applied a time-dependent advection-diffusion-reaction model that includes the effects of sedimentation, compaction,more » solute diffusion, and microbial methane generation. Microbial methane generation depends on the amount of metabolizable organic carbon deposited at the seafloor, whose progressive degradation produces methane beneath the sulfate reduction zone. If the amount of organic carbon entering the methanogenic zone is kept constant in time, we found that the computed amounts of hydrate formed in discrete intervals within the GHSZ are well below those estimated from observations. On the other hand, if the deposition of organic carbon is higher in a given time interval, methane generation during burial is more intense in the corresponding sediment interval, resulting in enhanced hydrate formation. With variations in organic carbon deposition comparable to those generally observed in continental margins, our model was able to reproduce the methane hydrate contents that were estimated from drilling. These results support the suggestion that in situ microbial generation associated with transient organic carbon deposition is the source of methane that forms isolated intervals of hydrate-filled veins in fine-grained sediments.« less

Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on muscle force production in people with spinal cord injury (SCI).

PubMed

Bochkezanian, Vanesa; Newton, Robert U; Trajano, Gabriel S; Vieira, Amilton; Pulverenti, Timothy S; Blazevich, Anthony J

2018-02-13

Neuromuscular electrical stimulation (NMES) is commonly used in skeletal muscles in people with spinal cord injury (SCI) with the aim of increasing muscle recruitment and thus muscle force production. NMES has been conventionally used in clinical practice as functional electrical stimulation (FES), using low levels of evoked force that cannot optimally stimulate muscular strength and mass improvements, and thus trigger musculoskeletal changes in paralysed muscles. The use of high intensity intermittent NMES training using wide-pulse width and moderate-intensity as a strength training tool could be a promising method to increase muscle force production in people with SCI. However, this type of protocol has not been clinically adopted because it may generate rapid muscle fatigue and thus prevent the performance of repeated high-intensity muscular contractions in paralysed muscles. Moreover, superimposing patellar tendon vibration onto the wide-pulse width NMES has been shown to elicit further increases in impulse or, at least, reduce the rate of fatigue in repeated contractions in able-bodied populations, but there is a lack of evidence to support this argument in people with SCI. Nine people with SCI received two NMES protocols with and without superimposing patellar tendon vibration on different days (i.e. STIM and STIM+vib), which consisted of repeated 30 Hz trains of 58 wide-pulse width (1000 μs) symmetric biphasic pulses (0.033-s inter-pulse interval; 2 s stimulation train; 2-s inter-train interval) being delivered to the dominant quadriceps femoris. Starting torque was 20% of maximal doublet-twitch torque and stimulations continued until torque declined to 50% of the starting torque. Total knee extensor impulse was calculated as the primary outcome variable. Total knee extensor impulse increased in four subjects when patellar tendon vibration was imposed (59.2 ± 15.8%) but decreased in five subjects (- 31.3 ± 25.7%). However, there were no statistically significant differences between these sub-groups or between conditions when the data were pooled. Based on the present results there is insufficient evidence to conclude that patellar tendon vibration provides a clear benefit to muscle force production or delays muscle fatigue during wide-pulse width, moderate-intensity NMES in people with SCI. ACTRN12618000022268 . Date: 11/01/2018. Retrospectively registered.

microRNA Biomarkers to Generate Sensitivity to Abiraterone-Resistant Prostate Cancer

DTIC Science & Technology

2017-09-01

CYP17A1 inhibition with abiraterone in castration- resistant prostate cancer : induction of steroidogenesis and androgen receptor splice variants...AWARD NUMBER: W81XWH-15-1-0353 TITLE: microRNA Biomarkers to Generate Sensitivity to Abiraterone-Resistant Prostate Cancer PRINCIPAL...TITLE AND SUBTITLE microRNA Biomarkers to Generate Sensitivity to Abiraterone- Resistant Prostate Cancer 5a. CONTRACT NUMBER 5b. GRANT NUMBER

Modeling the formation of methane hydrate-bearing intervals in fine-grained sediments

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

Malinverno, Alberto; Cook, Ann; Daigle, Hugh

Sediment grain size exerts a fundamental control on how methane hydrates are distributed within the pore space. Fine-grained muds are the predominant sediments in continental margins, and hydrates in these sediments have often been observed in semi-vertical veins and fractures. In several instances, these hydrate veins/fractures are found in discrete depth intervals a few tens meters thick within the gas hydrate stability zone (GHSZ) surrounded by hydrate-free sediments above and below. As they are not obviously connected with free gas occurring beneath the base of the GHSZ, these isolated hydrate-bearing intervals have been interpreted as formed by microbial methane generatedmore » in situ. To investigate further the formation of these hydrate deposits, we applied a time-dependent advection-diffusion-reaction model that includes the effects of sedimentation, solute diffusion, and microbial methane generation. The microbial methane generation term depends on the amount of metabolizable organic carbon deposited at the seafloor, which is degraded at a prescribed rate resulting in methane formation beneath the sulfate reduction zone. In the model, methane hydrate precipitates once the dissolved methane concentration is greater than solubility, or hydrate dissolves if concentration goes below solubility. If the deposition of organic carbon at the seafloor is kept constant in time, we found that the predicted amounts of hydrate formed in discrete intervals within the GHSZ are much less than those estimated from observations. We then investigated the effect of temporal variations in the deposition of organic carbon. If greater amounts of organic carbon are deposited during some time interval, methane generation is enhanced during burial in the corresponding sediment interval. With variations in organic carbon deposition that are consistent with observations in continental margin sediments, we were able to reproduce the methane hydrate contents estimated in discrete depth intervals. Our results support the suggestion that in situ microbial methane generation is the source for hydrates within fine-grained sediments.« less

SABRE observations of Pi2 pulsations: case studies

NASA Astrophysics Data System (ADS)

Bradshaw, E. G.; Lester, M.

1997-01-01

The characteristics of substorm-associated Pi2 pulsations observed by the SABRE coherent radar system during three separate case studies are presented. The SABRE field of view is well positioned to observe the differences between the auroral zone pulsation signature and that observed at mid-latitudes. During the first case study the SABRE field of view is initially in the eastward electrojet, equatorward and to the west of the substorm-enhanced electrojet current. As the interval progresses, the western, upward field-aligned current of the substorm current wedge moves westward across the longitudes of the radar field of view. The westward motion of the wedge is apparent in the spatial and temporal signatures of the associated Pi2 pulsation spectra and polarisation sense. During the second case study, the complex field-aligned and ionospheric currents associated with the pulsation generation region move equatorward into the SABRE field of view and then poleward out of it again after the third pulsation in the series. The spectral content of the four pulsations during the interval indicate different auroral zone and mid-latitude signatures. The final case study is from a period of low magnetic activity when SABRE observes a Pi2 pulsation signature from regions equatorward of the enhanced substorm currents. There is an apparent mode change between the signature observed by SABRE in the ionosphere and that on the ground by magnetometers at latitudes slightly equatorward of the radar field of view. The observations are discussed in terms of published theories of the generation mechanisms for this type of pulsation. Different signatures are observed by SABRE depending on the level of magnetic activity and the position of the SABRE field of view relative to the pulsation generation region. A twin source model for Pi2 pulsation generation provides the clearest explanation of the signatures observed Acknowledgements. The authors are grateful to Prof. D. J. Southwood (Imperial College, London), J. C. Samson (University of Alberta, Edmonton), L. J. Lanzerotti (AT&T Bell Laboratories), A. Wolfe (New York City Technical College) and to Dr. M. Vellante (University of LÁquila) for helpful discussions. They also thank Dr. A. Meloni (Istituto Nazionale di Geofisica, Roma) who made available geomagnetic field observations from LÁquila Geomagnetic Observatory. This research activity at LÁquila is supported by MURST (40% and 60% contracts) and by GIFCO/CNR. Topical Editor K.-H. Glaßmeier thanks C. Waters and S. Fujita for their help in evaluating this paper.-> Correspondence to :P. Francia->

Drebrin-like protein DBN-1 is a sarcomere component that stabilizes actin filaments during muscle contraction.

PubMed

Butkevich, Eugenia; Bodensiek, Kai; Fakhri, Nikta; von Roden, Kerstin; Schaap, Iwan A T; Majoul, Irina; Schmidt, Christoph F; Klopfenstein, Dieter R

2015-07-06

Actin filament organization and stability in the sarcomeres of muscle cells are critical for force generation. Here we identify and functionally characterize a Caenorhabditis elegans drebrin-like protein DBN-1 as a novel constituent of the muscle contraction machinery. In vitro, DBN-1 exhibits actin filament binding and bundling activity. In vivo, DBN-1 is expressed in body wall muscles of C. elegans. During the muscle contraction cycle, DBN-1 alternates location between myosin- and actin-rich regions of the sarcomere. In contracted muscle, DBN-1 is accumulated at I-bands where it likely regulates proper spacing of α-actinin and tropomyosin and protects actin filaments from the interaction with ADF/cofilin. DBN-1 loss of function results in the partial depolymerization of F-actin during muscle contraction. Taken together, our data show that DBN-1 organizes the muscle contractile apparatus maintaining the spatial relationship between actin-binding proteins such as α-actinin, tropomyosin and ADF/cofilin and possibly strengthening actin filaments by bundling.

Work Done by Titin Protein Folding Assists Muscle Contraction.

PubMed

Rivas-Pardo, Jaime Andrés; Eckels, Edward C; Popa, Ionel; Kosuri, Pallav; Linke, Wolfgang A; Fernández, Julio M

2016-02-16

Current theories of muscle contraction propose that the power stroke of a myosin motor is the sole source of mechanical energy driving the sliding filaments of a contracting muscle. These models exclude titin, the largest protein in the human body, which determines the passive elasticity of muscles. Here, we show that stepwise unfolding/folding of titin immunoglobulin (Ig) domains occurs in the elastic I band region of intact myofibrils at physiological sarcomere lengths and forces of 6-8 pN. We use single-molecule techniques to demonstrate that unfolded titin Ig domains undergo a spontaneous stepwise folding contraction at forces below 10 pN, delivering up to 105 zJ of additional contractile energy, which is larger than the mechanical energy delivered by the power stroke of a myosin motor. Thus, it appears inescapable that folding of titin Ig domains is an important, but as yet unrecognized, contributor to the force generated by a contracting muscle. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Weaker Seniors Exhibit Motor Cortex Hypoexcitability and Impairments in Voluntary Activation.

PubMed

Clark, Brian C; Taylor, Janet L; Hong, S Lee; Law, Timothy D; Russ, David W

2015-09-01

Weakness predisposes seniors to a fourfold increase in functional limitations. The potential for age-related degradation in nervous system function to contribute to weakness and physical disability has garnered much interest of late. In this study, we tested the hypothesis that weaker seniors have impairments in voluntary (neural) activation and increased indices of GABAergic inhibition of the motor cortex, assessed using transcranial magnetic stimulation. Young adults (N = 46; 21.2±0.5 years) and seniors (N = 42; 70.7±0.9 years) had their wrist flexion strength quantified along with voluntary activation capacity (by comparing voluntary and electrically evoked forces). Single-pulse transcranial magnetic stimulation was used to measure motor-evoked potential amplitude and silent period duration during isometric contractions at 15% and 30% of maximum strength. Paired-pulse transcranial magnetic stimulation was used to measure intracortical facilitation and short-interval and long-interval intracortical inhibition. The primary analysis compared seniors to young adults. The secondary analysis compared stronger seniors (top two tertiles) to weaker seniors (bottom tertile) based on strength relative to body weight. The most novel findings were that weaker seniors exhibited: (i) a 20% deficit in voluntary activation; (ii) ~20% smaller motor-evoked potentials during the 30% contraction task; and (iii) nearly twofold higher levels of long-interval intracortical inhibition under resting conditions. These findings indicate that weaker seniors exhibit significant impairments in voluntary activation, and that this impairment may be mechanistically associated with increased GABAergic inhibition of the motor cortex. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Elastase‐2, an angiotensin II‐generating enzyme, contributes to increased angiotensin II in resistance arteries of mice with myocardial infarction

PubMed Central

Silva, Marcondes A B; Durand, Marina T; Prado, Cibele M; Oliveira, Eduardo B; Ribeiro, Mauricio S; Salgado, Helio C; Salgado, Maria Cristina O; Tostes, Rita C

2017-01-01

Background and Purpose Angiotensin II (Ang II), whose generation largely depends on angiotensin‐converting enzyme (ACE) activity, mediates most of the renin‐angiotensin‐system (RAS) effects. Elastase‐2 (ELA‐2), a chymotrypsin‐serine protease elastase family member 2A, alternatively generates Ang II in rat arteries. Myocardial infarction (MI) leads to intense RAS activation, but mechanisms involved in Ang II‐generation in resistance arteries are unknown. We hypothesized that ELA‐2 contributes to vascular Ang II generation and cardiac damage in mice subjected to MI. Experimental Approach Concentration‐effect curves to Ang I and Ang II were performed in mesenteric resistance arteries from male wild type (WT) and ELA‐2 knockout (ELA‐2KO) mice subjected to left anterior descending coronary artery ligation (MI). Key Results MI size was similar in WT and ELA‐2KO mice. Ejection fraction and fractional shortening after MI similarly decreased in both strains. However, MI decreased stroke volume and cardiac output in WT, but not in ELA‐2KO mice. Ang I‐induced contractions increased in WT mice subjected to MI (MI‐WT) compared with sham‐WT mice. No differences were observed in Ang I reactivity between arteries from ELA‐2KO and ELA‐2KO subjected to MI (MI‐ELA‐2KO). Ang I contractions increased in arteries from MI‐WT versus MI‐ELA‐2KO mice. Chymostatin attenuated Ang I‐induced vascular contractions in WT mice, but did not affect Ang I responses in ELA‐2KO arteries. Conclusions and Implications These results provide the first evidence that ELA‐2 contributes to increased Ang II formation in resistance arteries and modulates cardiac function after MI, implicating ELA‐2 as a key player in ACE‐independent dysregulation of the RAS. PMID:28222221

Elastase-2, an angiotensin II-generating enzyme, contributes to increased angiotensin II in resistance arteries of mice with myocardial infarction.

PubMed

Becari, Christiane; Silva, Marcondes A B; Durand, Marina T; Prado, Cibele M; Oliveira, Eduardo B; Ribeiro, Mauricio S; Salgado, Helio C; Salgado, Maria Cristina O; Tostes, Rita C

2017-05-01

Angiotensin II (Ang II), whose generation largely depends on angiotensin-converting enzyme (ACE) activity, mediates most of the renin-angiotensin-system (RAS) effects. Elastase-2 (ELA-2), a chymotrypsin-serine protease elastase family member 2A, alternatively generates Ang II in rat arteries. Myocardial infarction (MI) leads to intense RAS activation, but mechanisms involved in Ang II-generation in resistance arteries are unknown. We hypothesized that ELA-2 contributes to vascular Ang II generation and cardiac damage in mice subjected to MI. Concentration-effect curves to Ang I and Ang II were performed in mesenteric resistance arteries from male wild type (WT) and ELA-2 knockout (ELA-2KO) mice subjected to left anterior descending coronary artery ligation (MI). MI size was similar in WT and ELA-2KO mice. Ejection fraction and fractional shortening after MI similarly decreased in both strains. However, MI decreased stroke volume and cardiac output in WT, but not in ELA-2KO mice. Ang I-induced contractions increased in WT mice subjected to MI (MI-WT) compared with sham-WT mice. No differences were observed in Ang I reactivity between arteries from ELA-2KO and ELA-2KO subjected to MI (MI-ELA-2KO). Ang I contractions increased in arteries from MI-WT versus MI-ELA-2KO mice. Chymostatin attenuated Ang I-induced vascular contractions in WT mice, but did not affect Ang I responses in ELA-2KO arteries. These results provide the first evidence that ELA-2 contributes to increased Ang II formation in resistance arteries and modulates cardiac function after MI, implicating ELA-2 as a key player in ACE-independent dysregulation of the RAS. © 2017 The British Pharmacological Society.

The Effect of Commonly Performed Exercises on the Levator Hiatus Area and the Length and Strength of Pelvic Floor Muscles in Postpartum Women.

PubMed

Siff, Lauren N; Hill, Audra J; Walters, Samantha J; Walters, Ginny; Walters, Mark D

2018-05-02

The aim oft his study was to compare the effects of 10 common exercises to traditional pelvic floor muscle (PFM) contractions (Kegel) on levator hiatus (LH) area and PFM length and strength. This is a cross-sectional study of 15 healthy postpartum women. Ten exercises were studied. These were common variations of leg, core, and back exercises used in yoga, Pilates, strength training, and physical therapy. Each participant performed all 10 exercises at a single visit in 2 examination settings: transperineal ultrasound and perineometry. Ultrasound measured the LH area and PFM length, and perineometry measured the muscle strength (peak squeeze pressure). Kegel generates an increase in squeeze pressure (24.3 cm H2O), shortens the muscles (-0.46 cm) and narrows the LH (-0.13 cm). The bird-dog and plank exercises were not different from Kegel in any measurement. While the leg-lift ultrasound dimensions are similar to Kegel, leg lifts generated peak squeeze pressures stronger than any other exercise (including Kegel). Whereas ultrasound dimensions were similar to Kegel, tucked and untucked squats and thigh adductions generated weaker contractions than Kegel. While crunch generated a squeeze pressure similar to Kegel, the ultrasound dimensions showed a significantly wider LH and longer muscle than Kegel. Bridge, clam, and plié exercises affected the PFMs differently than Kegel in all measures. Bird-dog, plank, and leg-lift exercises should be evaluated as alternative exercises to Kegel as they affect PFM strength and length and LH area similarly to Kegel, and leg lifts generate a stronger contraction than Kegel.

Emerging Regional Energy Security Issues China

DTIC Science & Technology

2009-09-29

moving toward European standards and taxation of least efficient vehicles www.csis.org | 7 China’s Energy Strategy - Clean Power Generation...Project Type of Contract Signature Date Estimated Value Contractor(s) Remarks Malaysian Amona (Main Contractor), Chinese COSL and CNOOC The first...infrastructure. List of Upstream Agreements Between Iran and China in Recent Years ** The original buyback contract w as signed betw een Malaysian Amona and

Understanding and Mitigating Protests of Department of Defense Acquisition Contracts

DTIC Science & Technology

2010-08-01

of delivery time that can lock out a rejected offeror from a market . Sixth, more complex contracts, like services versus products , generate more...The engineers, attorneys, or head of a business unit need to explain to the team that spent time working on a bid why the company lost. Executives...agency executives have to explain to their team, who also spent time working on the source solicitation, evaluation, and selection, why the company

QCD development in the early universe

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

Gromov, N. A., E-mail: gromov@dm.komisc.ru

The high-energy limit of Quantum Chromodynamics is generated by the contraction of its gauge groups. Contraction parameters are taken identical with those of the Electroweak Model and tend to zero when energy increases. At the infinite energy limit all quarks lose masses and have only one color degree of freedom. The limit model represents the development of Quantum Chromodynamics in the early Universe from the Big Bang up to the end of several milliseconds.

Beat-to-beat control of human optokinetic nystagmus slow phase durations

PubMed Central

Furman, Joseph M.

2016-01-01

This study provides the first clear evidence that the generation of optokinetic nystagmus fast phases (FPs) is a decision process that is influenced by performance of a concurrent disjunctive reaction time task (DRT). Ten subjects performed an auditory DRT during constant velocity optokinetic stimulation. Eye movements were measured in three dimensions with a magnetic search coil. Slow phase (SP) durations were defined as the interval between FPs. There were three main findings. Firstly, human optokinetic nystagmus SP durations are consistent with a model of a Gaussian basic interval generator (a type of biological clock), such that FPs can be triggered randomly at the end of a clock cycle (mean duration: 200–250 ms). Kolmogorov-Smirnov tests could not reject the modeled cumulative distribution for any data trials. Secondly, the FP need not be triggered at the end of a clock cycle, so that individual SP durations represent single or multiple clock cycles. Thirdly, the probability of generating a FP at the end of each interval generator cycle decreases significantly during performance of a DRT. These findings indicate that the alternation between SPs and FPs of optokinetic nystagmus is not purely reflexive. Rather, the triggering of the next FP is postponed more frequently if a recently presented DRT trial is pending action when the timing cycle expires. Hence, optokinetic nystagmus FPs show dual-task interference in a manner usually attributed to voluntary movements, including saccades. NEW & NOTEWORTHY This study provides the first clear evidence that the generation of optokinetic nystagmus (OKN) fast phases is a decision process that is influenced by performance of a concurrent disjunctive reaction time task (DRT). The slow phase (SP) durations are consistent with a Gaussian basic interval generator and multiple interval SP durations occur more frequently in the presence of the DRT. Hence, OKN shows dual-task interference in a manner observed in voluntary movements, such as saccades. PMID:27760815

Beat-to-beat control of human optokinetic nystagmus slow phase durations.

PubMed

Balaban, Carey D; Furman, Joseph M

2017-01-01

This study provides the first clear evidence that the generation of optokinetic nystagmus fast phases (FPs) is a decision process that is influenced by performance of a concurrent disjunctive reaction time task (DRT). Ten subjects performed an auditory DRT during constant velocity optokinetic stimulation. Eye movements were measured in three dimensions with a magnetic search coil. Slow phase (SP) durations were defined as the interval between FPs. There were three main findings. Firstly, human optokinetic nystagmus SP durations are consistent with a model of a Gaussian basic interval generator (a type of biological clock), such that FPs can be triggered randomly at the end of a clock cycle (mean duration: 200-250 ms). Kolmogorov-Smirnov tests could not reject the modeled cumulative distribution for any data trials. Secondly, the FP need not be triggered at the end of a clock cycle, so that individual SP durations represent single or multiple clock cycles. Thirdly, the probability of generating a FP at the end of each interval generator cycle decreases significantly during performance of a DRT. These findings indicate that the alternation between SPs and FPs of optokinetic nystagmus is not purely reflexive. Rather, the triggering of the next FP is postponed more frequently if a recently presented DRT trial is pending action when the timing cycle expires. Hence, optokinetic nystagmus FPs show dual-task interference in a manner usually attributed to voluntary movements, including saccades. This study provides the first clear evidence that the generation of optokinetic nystagmus (OKN) fast phases is a decision process that is influenced by performance of a concurrent disjunctive reaction time task (DRT). The slow phase (SP) durations are consistent with a Gaussian basic interval generator and multiple interval SP durations occur more frequently in the presence of the DRT. Hence, OKN shows dual-task interference in a manner observed in voluntary movements, such as saccades. Copyright © 2017 the American Physiological Society.

2nd Generation RLV Risk Definition Program

NASA Technical Reports Server (NTRS)

Davis, Robert M.; Stucker, Mark (Technical Monitor)

2000-01-01

The 2nd Generation RLV Risk Reduction Mid-Term Report summarizes the status of Kelly Space & Technology's activities during the first two and one half months of the program. This report was presented to the cognoscente Contracting Officer's Technical Representative (COTR) and selected Marshall Space Flight Center staff members on 26 September 2000. The report has been approved and is distributed on CD-ROM (as a PowerPoint file) in accordance with the terms of the subject contract, and contains information and data addressing the following: (1) Launch services demand and requirements; (2) Architecture, alternatives, and requirements; (3) Costs, pricing, and business cases analysis; (4) Commercial financing requirements, plans, and strategy; (5) System engineering processes and derived requirements; and (6) RLV system trade studies and design analysis.

The Chip-Scale Atomic Clock - Prototype Evaluation

DTIC Science & Technology

2007-11-01

39th Annual Precise Time and Time Interval (PTTI) Meeting THE CHIP-SCALE ATOMIC CLOCK – PROTOTYPE EVALUATION R. Lutwak *, A. Rashed...been supported by the Defense Advanced Research Projects Agency, Contract # NBCHC020050. REFERENCES [1] R. Lutwak , D. Emmons, W. Riley, and...D.C.), pp. 539-550. [2] R. Lutwak , D. Emmons, T. English, W. Riley, A. Duwel, M. Varghese, D. K. Serkland, and G. M. Peake, 2004, “The Chip-Scale

Calibrating GPS With TWSTFT For Accurate Time Transfer

DTIC Science & Technology

2008-12-01

40th Annual Precise Time and Time Interval (PTTI) Meeting 577 CALIBRATING GPS WITH TWSTFT FOR ACCURATE TIME TRANSFER Z. Jiang1 and...primary time transfer techniques are GPS and TWSTFT (Two-Way Satellite Time and Frequency Transfer, TW for short). 83% of UTC time links are...Calibrating GPS With TWSTFT For Accurate Time Transfer 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT

Partial-Interval Estimation of Count: Uncorrected and Poisson-Corrected Error Levels

ERIC Educational Resources Information Center

Yoder, Paul J.; Ledford, Jennifer R.; Harbison, Amy L.; Tapp, Jon T.

2018-01-01

A simulation study that used 3,000 computer-generated event streams with known behavior rates, interval durations, and session durations was conducted to test whether the main and interaction effects of true rate and interval duration affect the error level of uncorrected and Poisson-transformed (i.e., "corrected") count as estimated by…

Changes in passive tension of muscle in humans and animals after eccentric exercise

PubMed Central

Whitehead, N P; Weerakkody, N S; Gregory, J E; Morgan, D L; Proske, U

2001-01-01

This is a report of experiments on ankle extensor muscles of human subjects and a parallel series on the medial gastrocnemius of the anaesthetised cat, investigating the origin of the rise in passive tension after a period of eccentric exercise. Subjects exercised their triceps surae of one leg eccentrically by walking backwards on an inclined, forward-moving treadmill. Concentric exercise required walking forwards on a backwards-moving treadmill. For all subjects the other leg acted as a control. Immediately after both eccentric and concentric exercise there was a significant drop in peak active torque, but only after eccentric exercise was this accompanied by a shift in optimum angle for torque generation and a rise in passive torque. In the eccentrically exercised group some swelling and soreness developed but not until 24 h post-exercise. In the animal experiments the contracting muscle was stretched by 6 mm at 50 mm s−1 over a length range symmetrical about the optimum length for tension generation. Measurements of passive tension were made before and after the eccentric contractions, using small stretches to a range of muscle lengths, or with large stretches covering the full physiological range. After 150 eccentric contractions, passive tension was significantly elevated over most of the range of lengths. Measurements of work absorption during stretch-release cycles showed significant increases after the contractions. It is suggested that the rise in passive tension in both human and animal muscles after eccentric contractions is the result of development of injury contractures in damaged muscle fibres. PMID:11389215

Burial and thermal history of the Paradox Basin, Utah and Colorado, and petroleum potential of the Middle Pennsylvanian Paradox Basin

USGS Publications Warehouse

Nuccio, Vito F.; Condon, Steven M.

1996-01-01

The Ismay?Desert Creek interval and Cane Creek cycle of the Alkali Gulch interval of the Middle Pennsylvanian Paradox Formation in the Paradox Basin of Utah and Colorado contain excellent organic-rich source rocks having total organic carbon contents ranging from 0.5 to 11.0 percent. The source rocks in both intervals contain types I, II, and III organic matter and are potential source rocks for both oil and gas. Organic matter in the Ismay?Desert Creek interval and Cane Creek cycle of the Alkali Gulch interval (hereinafter referred to in this report as the ?Cane Creek cycle?) probably is more terrestrial in origin in the eastern part of the basin and is interpreted to have contributed to some of the gas produced there. Thermal maturity increases from southwest to northeast for both the Ismay?Desert Creek interval and Cane Creek cycle, following structural and burial trends throughout the basin. In the northernmost part of the basin, the combination of a relatively thick Tertiary sedimentary sequence and high basinal heat flow has produced very high thermal maturities. Although general thermal maturity trends are similar for both the Ismay?Desert Creek interval and Cane Creek cycle, actual maturity levels are higher for the Cane Creek due to the additional thickness (as much as several thousand feet) of Middle Pennsylvanian section. Throughout most of the basin, the Ismay?Desert Creek interval is mature and in the petroleum-generation window (0.10 to 0.50 production index (PI)), and both oil and gas are produced; in the south-central to southwestern part of the basin, however, the interval is marginally mature (0.10 PI) in the central part of the basin and is overmature (past the petroleum-generation window (>0.50 PI)) throughout most of the eastern part of the basin. The Cane Creek cycle generally produces oil and associated gas throughout the western and central parts of the basin and thermogenic gas in the eastern part of the basin. Burial and thermal-history models were constructed for six different areas of the Paradox Basin. In the Monument upwarp area, the least mature part of the basin, the Ismay?Desert Creek interval and Cane Creek cycle have thermal maturities of 0.10 and 0.20 PI and were buried to 13,400 ft and 14,300 ft, respectively. A constant heat flow through time of 40 mWm?2 (milliwatts per square meter) is postulated for this area. Significant petroleum generation began at 45 Ma for the Ismay?Desert Creek interval and at 69 Ma for the Cane Creek cycle. In the area around the confluence of the Green and Colorado Rivers, the Ismay?Desert Creek interval and Cane Creek cycle have thermal maturities of 0.20 and 0.25 PI and were buried to 13,000 ft and 14,200 ft, respectively. A constant heat flow through time of 42 mWm?2 is postulated for this area. Significant petroleum generation began at 60 Ma for the Ismay?Desert Creek interval and at 75 Ma for the Cane Creek cycle. In the area around the town of Green River, Utah, the Ismay?Desert Creek interval and Cane Creek cycle have thermal maturities of 0.60 and greater and were buried to 14,000 ft and 15,400 ft, respectively. A constant heat flow through time of 53 mWm?2 is proposed for this area. Significant petroleum generation began at 82 Ma for the Ismay?Desert Creek interval and at 85 Ma for the Cane Creek cycle. Around Moab, Utah, in the deeper, eastern part of the basin, the Ismay?Desert Creek interval and Cane Creek cycle have thermal maturities of 0.30 and around 0.35 PI and were buried to 18,250 ft and 22,000 ft, respectively. A constant heat flow through time of 40 mWm?2 is postulated for this area. Significant petroleum generation began at 79 Ma for the Ismay?Desert Creek interval and at 90 Ma for the Cane Creek cycle. At Lisbon Valley, also in the structurally deeper part of the basin, the Ismay?

A continuously self regenerating high-flux neutron-generator facility

NASA Astrophysics Data System (ADS)

Rogers, A. M.; Becker, T. A.; Bernstein, L. A.; van Bibber, K.; Bleuel, D. L.; Chen, A. X.; Daub, B. H.; Goldblum, B. L.; Firestone, R. B.; Leung, K.-N.; Renne, P. R.; Waltz, C.

2013-10-01

A facility based on a next-generation, high-flux D-D neutron generator (HFNG) is being constructed at UC Berkeley. The current generator, designed around two RF-driven multicusp deuterium ion sources, is capable of producing a neutron output of >1011 n/s. A specially designed titanium-coated copper target located between the ion sources accelerates D+ ions up to 150 keV, generating 2.45 MeV neutrons through the d(d,3He)n fusion reaction. Deuterium in the target is self loaded and regenerating through ion implantation, enabling stable and continuous long-term operation. The proposed science program is focused on pioneering advances in the 40Ar/39Ar dating technique for geochronology, new nuclear data measurements, basic nuclear science research including statistical model studies of radiative-strength functions and level densities, and education. An overview of the facility and its unique capabilities as well as first measurements from the HFNG commissioning will be presented. Work supported by NSF Grant No. EAR-0960138, U.S. DOE LBL Contract No. DE-AC02-05CH11231, and U.S. DOE LLNL Contract No. DE-AC52-07NA27344.

Optimal design of vertebrate and insect sarcomeres.

PubMed

Otten, E

1987-01-01

This paper offers a model for the normalized length-tension relation of a muscle fiber based upon sarcomere design. Comparison with measurements published by Gordon et al. ('66) shows an accurate fit as long as the inhomogeneity of sarcomere length in a single muscle fiber is taken into account. Sequential change of filament length and the length of the cross-bridge-free zone leads the model to suggest that most vertebrate sarcomeres tested match the condition of optimal construction for the output of mechanical energy over a full sarcomere contraction movement. Joint optimization of all three morphometric parameters suggests that a slightly better (0.3%) design is theoretically possible. However, this theoretical sarcomere, optimally designed for the conversion of energy, has a low normalized contraction velocity; it provides a poorer match to the combined functional demands of high energy output and high contraction velocity than the real sarcomeres of vertebrates. The sarcomeres in fish myotomes appear to be built suboptimally for isometric contraction, but built optimally for that shortening velocity generating maximum power. During swimming, these muscles do indeed contract concentrically only. The sarcomeres of insect asynchronous flight muscles contract only slightly. They are not built optimally for maximum output of energy across the full range of contraction encountered in vertebrate sarcomeres, but are built almost optimally for the contraction range that they do in fact employ.

TraceContract

NASA Technical Reports Server (NTRS)

Kavelund, Klaus; Barringer, Howard

2012-01-01

TraceContract is an API (Application Programming Interface) for trace analysis. A trace is a sequence of events, and can, for example, be generated by a running program, instrumented appropriately to generate events. An event can be any data object. An example of a trace is a log file containing events that a programmer has found important to record during a program execution. Trace - Contract takes as input such a trace together with a specification formulated using the API and reports on any violations of the specification, potentially calling code (reactions) to be executed when violations are detected. The software is developed as an internal DSL (Domain Specific Language) in the Scala programming language. Scala is a relatively new programming language that is specifically convenient for defining such internal DSLs due to a number of language characteristics. This includes Scala s elegant combination of object-oriented and functional programming, a succinct notation, and an advanced type system. The DSL offers a combination of data-parameterized state machines and temporal logic, which is novel. As an extension of Scala, it is a very expressive and convenient log file analysis framework.

Neuroprosthetic-enabled control of graded arm muscle contraction in a paralyzed human.

PubMed

Friedenberg, David A; Schwemmer, Michael A; Landgraf, Andrew J; Annetta, Nicholas V; Bockbrader, Marcia A; Bouton, Chad E; Zhang, Mingming; Rezai, Ali R; Mysiw, W Jerry; Bresler, Herbert S; Sharma, Gaurav

2017-08-21

Neuroprosthetics that combine a brain computer interface (BCI) with functional electrical stimulation (FES) can restore voluntary control of a patients' own paralyzed limbs. To date, human studies have demonstrated an "all-or-none" type of control for a fixed number of pre-determined states, like hand-open and hand-closed. To be practical for everyday use, a BCI-FES system should enable smooth control of limb movements through a continuum of states and generate situationally appropriate, graded muscle contractions. Crucially, this functionality will allow users of BCI-FES neuroprosthetics to manipulate objects of different sizes and weights without dropping or crushing them. In this study, we present the first evidence that using a BCI-FES system, a human with tetraplegia can regain volitional, graded control of muscle contraction in his paralyzed limb. In addition, we show the critical ability of the system to generalize beyond training states and accurately generate wrist flexion states that are intermediate to training levels. These innovations provide the groundwork for enabling enhanced and more natural fine motor control of paralyzed limbs by BCI-FES neuroprosthetics.

Poorly Understood Aspects of Striated Muscle Contraction

PubMed Central

Månsson, Alf

2015-01-01

Muscle contraction results from cyclic interactions between the contractile proteins myosin and actin, driven by the turnover of adenosine triphosphate (ATP). Despite intense studies, several molecular events in the contraction process are poorly understood, including the relationship between force-generation and phosphate-release in the ATP-turnover. Different aspects of the force-generating transition are reflected in the changes in tension development by muscle cells, myofibrils and single molecules upon changes in temperature, altered phosphate concentration, or length perturbations. It has been notoriously difficult to explain all these events within a given theoretical framework and to unequivocally correlate observed events with the atomic structures of the myosin motor. Other incompletely understood issues include the role of the two heads of myosin II and structural changes in the actin filaments as well as the importance of the three-dimensional order. We here review these issues in relation to controversies regarding basic physiological properties of striated muscle. We also briefly consider actomyosin mutation effects in cardiac and skeletal muscle function and the possibility to treat these defects by drugs. PMID:25961006

Poorly understood aspects of striated muscle contraction.

PubMed

Månsson, Alf; Rassier, Dilson; Tsiavaliaris, Georgios

2015-01-01

Muscle contraction results from cyclic interactions between the contractile proteins myosin and actin, driven by the turnover of adenosine triphosphate (ATP). Despite intense studies, several molecular events in the contraction process are poorly understood, including the relationship between force-generation and phosphate-release in the ATP-turnover. Different aspects of the force-generating transition are reflected in the changes in tension development by muscle cells, myofibrils and single molecules upon changes in temperature, altered phosphate concentration, or length perturbations. It has been notoriously difficult to explain all these events within a given theoretical framework and to unequivocally correlate observed events with the atomic structures of the myosin motor. Other incompletely understood issues include the role of the two heads of myosin II and structural changes in the actin filaments as well as the importance of the three-dimensional order. We here review these issues in relation to controversies regarding basic physiological properties of striated muscle. We also briefly consider actomyosin mutation effects in cardiac and skeletal muscle function and the possibility to treat these defects by drugs.

Dynamics and Breakup of a Contracting Viscous Filament

NASA Astrophysics Data System (ADS)

Wilkes, Edward; Notz, Patrick; Ambravaneswaran, Bala; Basaran, Osman

1999-11-01

Free viscous filaments are formed during the breakup of liquid drops and jets. Such filaments are typically precursors of satellite droplets that are often undesirable in applications such as ink-jet printing. In this paper, the contraction of an axisymmetric liquid filament due to action of surface tension is studied theoretically. The analysis is based on solving (a) the full Navier-Stokes system in two-dimensions (2-d) and (b) a one-dimensional (1-d) approximation of the exact equations based on slender-jet theory. The rigorous, 2-d calculations are carried out with finite element algorithms using either algebraic or elliptic mesh generation. As the filament contracts, bulbous regions form at its two ends. When the initial aspect ratio a/b and/or the Reynolds number Re are sufficiently low, the ends coalesce into an oscillating free drop. Filament breakup occurs when a/b and/or Re are sufficiently high. The 2-d algorithms reveal for the first time that liquid filaments of finite viscosity can overturn prior to interface rupture. The power of elliptic mesh generation over algebraic methods in analyzing such situations is highlighted.

Effect of near infrared lasers and glycated chitosan on myofibroblast differentiation and contraction

NASA Astrophysics Data System (ADS)

Obioma, Christiana C.; Layton, Elivia; Doan, Khue Tu; Xu, Gang; Zhou, Feifan; Chen, Wei R.; Vaughan, Melville B.

2018-02-01

The ability to modulate myofibroblast phenotype will have an impact in wound healing, aging, cancer, and Dupuytren's contracture development. Our project focused on investigating the effect of 808 nm laser wavelength on the presence of myofibroblast and contraction using anchored delayed release collagen lattice models. Fibroblast cells were cultured and suspended in collagen lattices in the presence or absence of glycated chitosan (GC) to mimic a wound healing environment in-vitro. The cells were allowed to generate maximum tension for 6 days followed by laser light stimulation. The total number of cells and presence of fibroblast proliferation and differentiation into myofibroblasts was determined using immunostaining followed by fluorescent microscope photography. Lattice tension generation was assessed by releasing the lattices from their anchorage and measuring their diameters. Control lattices contracted more than GC lattices. Myofibroblast differentiation was slightly higher in the control group. Repeats of the experiment are needed to confirm our results to determine if near infra-red laser radiation can be applied to treat open wounds and study tumor stromas.

Simulation studies of circular muscle contraction, longitudinal muscle shortening, and their coordination in esophageal transport.

PubMed

Kou, Wenjun; Pandolfino, John E; Kahrilas, Peter J; Patankar, Neelesh A

2015-08-15

On the basis of a fully coupled active musculomechanical model for esophageal transport, we aimed to find the roles of circular muscle (CM) contraction and longitudinal muscle (LM) shortening in esophageal transport, and the influence of their coordination. Two groups of studies were conducted using a computational model. In the first group, bolus transport with only CM contraction, only LM shortening, or both was simulated. Overall features and detailed information on pressure and the cross-sectional area (CSA) of mucosal and the two muscle layers were analyzed. In the second group, bolus transport with varying delay in CM contraction or LM shortening was simulated. The effect of delay on esophageal transport was studied. For cases showing abnormal transport, pressure and CSA were further analyzed. CM contraction by itself was sufficient to transport bolus, but LM shortening by itself was not. CM contraction decreased the CSA and the radius of the muscle layer locally, but LM shortening increased the CSA. Synchronized CM contraction and LM shortening led to overlapping of muscle CSA and pressure peaks. Advancing LM shortening adversely influenced bolus transport, whereas lagging LM shortening was irrelevant to bolus transport. In conclusion, CM contraction generates high squeezing pressure, which plays a primary role in esophageal transport. LM shortening increases muscle CSA, which helps to strengthen CM contraction. Advancing LM shortening decreases esophageal distensibility in the bolus region. Lagging LM shortening no longer helps esophageal transport. Synchronized CM contraction and LM shortening seems to be most effective for esophageal transport. Copyright © 2015 the American Physiological Society.

Indirect methods for reference interval determination - review and recommendations.

PubMed

Jones, Graham R D; Haeckel, Rainer; Loh, Tze Ping; Sikaris, Ken; Streichert, Thomas; Katayev, Alex; Barth, Julian H; Ozarda, Yesim

2018-04-19

Reference intervals are a vital part of the information supplied by clinical laboratories to support interpretation of numerical pathology results such as are produced in clinical chemistry and hematology laboratories. The traditional method for establishing reference intervals, known as the direct approach, is based on collecting samples from members of a preselected reference population, making the measurements and then determining the intervals. An alternative approach is to perform analysis of results generated as part of routine pathology testing and using appropriate statistical techniques to determine reference intervals. This is known as the indirect approach. This paper from a working group of the International Federation of Clinical Chemistry (IFCC) Committee on Reference Intervals and Decision Limits (C-RIDL) aims to summarize current thinking on indirect approaches to reference intervals. The indirect approach has some major potential advantages compared with direct methods. The processes are faster, cheaper and do not involve patient inconvenience, discomfort or the risks associated with generating new patient health information. Indirect methods also use the same preanalytical and analytical techniques used for patient management and can provide very large numbers for assessment. Limitations to the indirect methods include possible effects of diseased subpopulations on the derived interval. The IFCC C-RIDL aims to encourage the use of indirect methods to establish and verify reference intervals, to promote publication of such intervals with clear explanation of the process used and also to support the development of improved statistical techniques for these studies.

Investment Strategies for Improving Fifth-Generation Fighter Training

DTIC Science & Technology

2011-01-01

The pod is part of the fifth-generation P5 Combat Training System/Tactical Combat Training System designed by Cubic Corporation. (See Shamim , 2007...http://www.rand.org/pubs/monograph_reports/MR1286/ Shamim , Asif, “F-35 Lightning II News: Cubic Lands Contract for F-35 ACMI Training System,” F-16.net

Generation and migration of Bitumen and oil from the oil shale interval of the Eocene Green River formation, Uinta Basin, Utah

USGS Publications Warehouse

Johnson, Ronald C.; Birdwell, Justin E.; Mercier, Tracey J.

2016-01-01

The results from the recent U.S. Geological Survey assessment of in-place oil shale resources of the Eocene Green River Formation, based primarily on the Fischer assay method, are applied herein to define areas where the oil shale interval is depleted of some of its petroleum-generating potential along the deep structural trough of the basin and to make: (1) a general estimates of the amount of this depletion, and (2) estimate the total volume of petroleum generated. Oil yields (gallons of oil per ton of rock, GPT) and in-place oil (barrels of oil per acre, BPA) decrease toward the structural trough of the basin, which represents an offshore lacustrine area that is believed to have originally contained greater petroleum-generating potential than is currently indicated by measured Fischer assay oil yields. Although this interval is considered to be largely immature for oil generation based on vitrinite reflectance measurements, the oil shale interval is a likely source for the gilsonite deposits and much of the tar sands in the basin. Early expulsion of petroleum may have occurred due to the very high organic carbon content and oil-prone nature of the Type I kerogen present in Green River oil shale. In order to examine the possible sources and migration pathways for the tar sands and gilsonite deposits, we have created paleogeographic reconstructions of several oil shale zones in the basin as part of this study.

Generating Variable Wind Profiles and Modeling Their Effects on Small-Arms Trajectories

DTIC Science & Technology

2016-04-01

ARL-TR-7642 ● APR 2016 US Army Research Laboratory Generating Variable Wind Profiles and Modeling Their Effects on Small-Arms... Wind Profiles and Modeling Their Effects on Small-Arms Trajectories by Timothy A Fargus Weapons and Materials Research Directorate, ARL...Generating Variable Wind Profiles and Modeling Their Effects on Small-Arms Trajectories 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

EMERGE: Engineered Materials that Create Environments for ReGeneration via Electric Field

DTIC Science & Technology

2016-10-01

Recruitment of multiple cell lines by collagen-synthetic copolymer matrices in corneal regeneration ,” Biomaterials (2004). A) B) REDD-2016-537...AWARD NUMBER: W81XWH-14-1-0542 TITLE: EMERGE: Engineered Materials that Create Environments for ReGeneration via Electric Field PRINCIPAL...23 Sep 2016 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER EMERGE: Engineered Materials that Create Environments for ReGeneration via Electric Field

New Generation of Military Members Provides Opportunity to Reform Military Benefits

DTIC Science & Technology

2013-03-01

only 9% for those in companies with less than a 100 workers. A 2008 survey found that 72% of employees cite retirement benefits as an important factor...New Generation of Military Members Provides Opportunity to Reform Military Benefits by Lieutenant Colonel Todd D...SUBTITLE New Generation of Military Members Provides Opportunity to Reform Military Benefits 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

Are polygonal faults the keystone for better understanding the timing of fluid migration in sedimentary basins?

NASA Astrophysics Data System (ADS)

Gay, Aurélien

2017-06-01

The initial sediment lithification starts with complex interactions involving minerals, surface water, decomposing organic matter and living organisms. This is the eogenesis domain (0 to 2 km below the seafloor) in which the sediments are subject to physical, chemical and mechanical transformations defining the early fabric of rocks. This interval is intensively prospected for its energy/mining resources (hydrocarbons, metal deposits, geothermal energy). In most basins worldwide it is composed of very fine-grained sediments and it is supposed to play the role of a seal for fluids migration. However, it is affected by polygonal faulting due to a volume loss during burial by contraction of clay sediments with a high smectite content. This process is of high interest for fractured reservoirs and/or cover integrity but it is not well constrained giving an uncertainty as this interval can either promote the migration of deeper fluids and the mineralized fluids intensifies diagenesis in the fracture planes, rendering this interval all the more impermeable. The next challenge will be to define where, when and how does this polygonal fault interval occur and this can only be done by understanding the behavior of clay grains and fluids during early burial.

Apparatus and method for data communication in an energy distribution network

DOEpatents

Hussain, Mohsin; LaPorte, Brock; Uebel, Udo; Zia, Aftab

2014-07-08

A system for communicating information on an energy distribution network is disclosed. In one embodiment, the system includes a local supervisor on a communication network, wherein the local supervisor can collect data from one or more energy generation/monitoring devices. The system also includes a command center on the communication network, wherein the command center can generate one or more commands for controlling the one or more energy generation devices. The local supervisor can periodically transmit a data signal indicative of the data to the command center via a first channel of the communication network at a first interval. The local supervisor can also periodically transmit a request for a command to the command center via a second channel of the communication network at a second interval shorter than the first interval. This channel configuration provides effective data communication without a significant increase in the use of network resources.

Functional anatomy of vagina muscles in the blood-feeding insect, Rhodnius prolixus.

PubMed

Chiang, R G; O'Donnell, M J

2009-11-01

The physiology of the muscles associated with the vagina in the blood-feeding insect, Rhodnius prolixus Stal, was investigated with the use of Methylene Blue staining to visualize the anatomy, and a micro force transducer to record spontaneous and neurally-evoked contractions. The vagina is associated with a dorsal muscle and a set of paired lateral muscles. The dorsal muscle extends from the base of the common oviduct to apodemes located laterally on sternite VIII, the first genital segment. The lateral muscles extend from a medially-located apodeme on the posterior edge of sternite VI around each side of the common oviduct to travel posteriorly along the side of the vagina before inserting laterally on apodemes on sternite VIII. The vagina muscles display spontaneous and neurally-evoked contractions that are prolonged but transient. The response to evoked contractions shows that the muscles are innervated by both excitatory and inhibitory motor axons. The degree of tension generated by evoked contractions is dependent on the frequency of stimulation with maximal tension being generated at 20-30Hz. This tension, which often exceeds 400mg, is transient and returns to a baseline within 1 to 2min during continuous stimulation. These results, which are the first to describe this chamber in this well-studied insect, are discussed with respect to the act of egg laying.

Single particle train ordering in microchannel based on inertial and vortex effects

NASA Astrophysics Data System (ADS)

Fan, Liang-Liang; Yan, Qing; Zhe, Jiang; Zhao, Liang

2018-06-01

A new microfluidic device for microparticle focusing and ordering in a single particle train is reported. The particle focusing and ordering are based on inertial and vortex effects in a microchannel with a series of suddenly contracted and widely expanded structures on one side. In the suddenly contracted regions, particles located near the contracted structures are subjected to a strong wall-effect lift force and momentum-change-induced inertial force due to the highly curved trajectory, migrating to the straight wall. A horizontal vortex is generated downstream of the contracted structure, which prevents the particle from getting close to the wall. In the widely expanded regions, the streamline is curved and no vortex is generated. The shear-gradient lift force and the momentum-change-induced inertial force are dominant for particle lateral migration, driving particles towards the wall of the expanded structures. Eventually, particles are focused and ordered in a single particle train by the combination effects of the inertial forces and the vortex. In comparison with other single-stream particle focusing methods, this device requires no sheath flow, is easy for fabrication and operation, and can work over a wide range of Reynolds numbers from 19.1–142.9. The highly ordered particle chain could be potentially utilized in a variety of lab-chip applications, including micro-flow cytometer, imaging and droplet-based cell entrapment.

High aspect ratio nanoholes in glass generated by femtosecond laser pulses with picosecond intervals

NASA Astrophysics Data System (ADS)

Ahn, Sanghoon; Choi, Jiyeon; Noh, Jiwhan; Cho, Sung-Hak

2018-02-01

Because of its potential uses, high aspect ratio nanostructures have been interested for last few decades. In order to generate nanostructures, various techniques have been attempted. Femtosecond laser ablation is one of techniques for generating nanostructures inside a transparent material. For generating nanostructures by femtosecond laser ablation, previous studies have been attempted beam shaping such as Bessel beam and temporal tailored beam. Both methods suppress electron excitation at near surface and initiate interference of photons at certain depth. Recent researches indicate that shape of nanostructures is related with temporal change of electron density and number of self-trapped excitons. In this study, we try to use the temporal change of electron density induced by femtosecond laser pulse for generating high aspect ratio nanoholes. In order to reveal the effect of temporal change of electron density, secondary pulses are irradiated from 100 to 1000 ps after the irradiation of first pulse. Our result shows that diameter of nanoholes is increasing and depth of nanoholes is decreasing as pulse to pulse interval is getting longer. With manipulating of pulse to pulse interval, we could generate high aspect ratio nanoholes with diameter of 250-350 nm and depth of 4∼6 μm inside a glass.

Managing Financial Risk to Hydropower in Snow Dominated Systems: A Hetch Hetchy Case Study

NASA Astrophysics Data System (ADS)

Hamilton, A. L.; Characklis, G. W.; Reed, P. M.

2017-12-01

Hydropower generation in snow dominated systems is vulnerable to severe shortfalls in years with low snowpack. Meanwhile, generators are also vulnerable to variability in electricity demand and wholesale electricity prices, both of which can be impacted by factors such as temperature and natural gas price. Year-to-year variability in these underlying stochastic variables leads to financial volatility and the threat of low revenue periods, which can be highly disruptive for generators with large fixed operating costs and debt service. In this research, the Hetch Hetchy Power system is used to characterize financial risk in a snow dominated hydropower system. Owned and operated by the San Francisco Public Utilities Commission, Hetch Hetchy generates power for its own municipal operations and sells excess power to irrigation districts, as well as on the wholesale market. This investigation considers the effects of variability in snowpack, temperature, and natural gas price on Hetch Hetchy Power's yearly revenues. This information is then used to evaluate the effectiveness of various financial risk management tools for hedging against revenue variability. These tools are designed to mitigate against all three potential forms of financial risk (i.e. low hydropower generation, low electricity demand, and low/high electricity price) and include temperature-based derivative contracts, natural gas price-based derivative contracts, and a novel form of snowpack-based index insurance contract. These are incorporated into a comprehensive risk management portfolio, along with self-insurance in which the utility buffers yearly revenue volatility using a contingency fund. By adaptively managing the portfolio strategy, a utility can efficiently spread yearly risks over a multi-year time horizon. The Borg Multiobjective Evolutionary Algorithm is used to generate a set of Pareto optimal portfolio strategies, which are used to compare the tradeoffs in objectives such as expected revenues, low revenues, revenue volatility, and portfolio complexity.

Indirect coupling of phosphate release to de novo tension generation during muscle contraction.

PubMed Central

Davis, J S; Rodgers, M E

1995-01-01

A key question in muscle contraction is how tension generation is coupled to the chemistry of the actomyosin ATPase. Biochemical and mechanochemical experiments link tension generation to a change in structure associated with phosphate release. Length-jump and temperature-jump experiments, on the other hand, implicate phase 2slow, a significantly faster, markedly strain-sensitive kinetic process in tension generation. We use a laser temperature jump to probe the kinetics and mechanism of tension generation in skinned rabbit psoas fibers--an appropriate method since both phosphate release and phase 2slow are readily perturbed by temperature. Kinetics characteristic of the structural change associated with phosphate release are observed only when phosphate is added to fibers. When present, it causes a reduction in fiber tension; otherwise, no force is generated when it is perturbed. We therefore exclude this step from tension generation. The kinetics of de novo tension generation by the temperature-jump equivalent of phase 2slow appear unaffected by phosphate binding. We therefore propose that phosphate release is indirectly coupled to de novo tension generation via a steady-state flux through an irreversible step. We conclude that tension generation occurs in the absence of chemical change as the result of an entropy-driven transition between strongly bound crossbridges in the actomyosin-ADP state. The mechanism resembles the operation of a clock, with phosphate release providing the energy to tension the spring, and the irreversible step functions as the escapement mechanism, which is followed in turn by tension generation as the movement of the hands. Images Fig. 6 PMID:7479824

Calculating Confidence Intervals for Regional Economic Impacts of Recreastion by Bootstrapping Visitor Expenditures

Treesearch

Donald B.K. English

2000-01-01

In this paper I use bootstrap procedures to develop confidence intervals for estimates of total industrial output generated per thousand tourist visits. Mean expenditures from replicated visitor expenditure data included weights to correct for response bias. Impacts were estimated with IMPLAN. Ninety percent interval endpoints were 6 to 16 percent above or below the...

Modulation of the cortical silent period elicited by single- and paired-pulse transcranial magnetic stimulation

PubMed Central

2013-01-01

Background The cortical silent period (CSP) elicited by transcranial magnetic stimulation (TMS) is affected by changes in TMS intensity. Some studies have shown that CSP is shortened or prolonged by short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF), Those studies, however, used different TMS intensities to adjust the amplitude of the motor evoked potential (MEP). Therefore, it is unclear whether changes in CSP duration are induced by changes in TMS intensities or by SICI and ICF. The purpose of this study was to confirm the effects of muscle contractions and stimulus intensities on MEP amplitude and the duration of CSP induced by single-pulse TMS and to clarify the effects of SICI and ICF on CSP duration. MEP evoked by TMS was detected from the right first dorsal interosseous muscle in 15 healthy subjects. First, MEP and CSP were induced by single-pulse TMS with an intensity of 100% active motor threshold (AMT) at four muscle contraction levels [10%, 30%, 50%, and 70% electromyogram (EMG)]. Next, MEP and CSP were induced by seven TMS intensities (100%, 110%, 120%, 130%, 140%, 150%, and 160% AMT) during muscle contraction of 10% EMG. Finally, SICI and ICF were recorded at the four muscle contraction levels (0%, 10%, 30%, and 50% EMG). Results MEP amplitudes increased with increases in muscle contraction and stimulus intensity. However, CSP duration did not differ at different muscle contraction levels and was prolonged with increases in stimulus intensity. CSP was shortened with SICI compared with CSP induced by single-pulse TMS and with ICF at all muscle contraction levels, whereas CSP duration was not significantly changed with ICF. Conclusions We confirmed that CSP duration is affected by TMS intensity but not by the muscle contraction level. This study demonstrated that CSP is shortened with SICI, but it is not altered with ICF. These results indicate that after SICI, CSP duration is affected by the activity of inhibitory intermediate neurons that are activated by the conditioning SICI stimulus. PMID:23547559

Structural dynamics of the skeletal muscle fiber by second harmonic generation

NASA Astrophysics Data System (ADS)

Nucciotti, V.; Stringari, C.; Sacconi, L.; Vanzi, F.; Linari, M.; Piazzesi, G.; Lombardi, V.; Pavone, F. S.

2008-02-01

The high degree of structural order in skeletal muscle allows imaging of this tissue by Second Harmonic Generation (SHG). As previously found (Vanzi et al., J. Muscle Cell Res. Motil. 2006) by fractional extraction of proteins, myosin is the source of SHG signal. A full characterization of the polarization-dependence of the SHG signal can provide very selective information on the orientation of the emitting proteins and their dynamics during contraction. We developed a line scan polarization method, allowing measurements of a full polarization curve in intact muscle fibers from skeletal muscle of the frog to characterize the SHG polarization dependence on different physiological states (resting, rigor and isometric tetanic contraction). The polarization data have been interpreted by means of a model in terms of the average orientation of SHG emitters.The different physiological states are characterized by distinct patterns of SHG polarization. The variation of the orientation of emitting molecules in relation to the physiological state of the muscle demonstrates that one part of SHG signal arises from the globular head of the myosin molecule that cross-links actin and myosin filaments. The dependence of the SHG modulation on the degree of overlap between actin and myosin filaments during an isometric contraction, provides the constraints to estimate the fraction of myosin heads generating the isometric force in the active muscle fiber.

Healthcare Blockchain System Using Smart Contracts for Secure Automated Remote Patient Monitoring.

PubMed

Griggs, Kristen N; Ossipova, Olya; Kohlios, Christopher P; Baccarini, Alessandro N; Howson, Emily A; Hayajneh, Thaier

2018-06-06

As Internet of Things (IoT) devices and other remote patient monitoring systems increase in popularity, security concerns about the transfer and logging of data transactions arise. In order to handle the protected health information (PHI) generated by these devices, we propose utilizing blockchain-based smart contracts to facilitate secure analysis and management of medical sensors. Using a private blockchain based on the Ethereum protocol, we created a system where the sensors communicate with a smart device that calls smart contracts and writes records of all events on the blockchain. This smart contract system would support real-time patient monitoring and medical interventions by sending notifications to patients and medical professionals, while also maintaining a secure record of who has initiated these activities. This would resolve many security vulnerabilities associated with remote patient monitoring and automate the delivery of notifications to all involved parties in a HIPAA compliant manner.

Mechanisms of reflex bladder activation by pudendal afferents

PubMed Central

Woock, John P.; Yoo, Paul B.

2011-01-01

Activation of pudendal afferents can evoke bladder contraction or relaxation dependent on the frequency of stimulation, but the mechanisms of reflex bladder excitation evoked by pudendal afferent stimulation are unknown. The objective of this study was to determine the contributions of sympathetic and parasympathetic mechanisms to bladder contractions evoked by stimulation of the dorsal nerve of the penis (DNP) in α-chloralose anesthetized adult male cats. Bladder contractions were evoked by DNP stimulation only above a bladder volume threshold equal to 73 ± 12% of the distension-evoked reflex contraction volume threshold. Bilateral hypogastric nerve transection (to eliminate sympathetic innervation of the bladder) or administration of propranolol (a β-adrenergic antagonist) decreased the stimulation-evoked and distension-evoked volume thresholds by −25% to −39%. Neither hypogastric nerve transection nor propranolol affected contraction magnitude, and robust bladder contractions were still evoked by stimulation at volume thresholds below the distension-evoked volume threshold. As well, inhibition of distention-evoked reflex bladder contractions by 10 Hz stimulation of the DNP was preserved following bilateral hypogastric nerve transection. Administration of phentolamine (an α-adrenergic antagonist) increased stimulation-evoked and distension-evoked volume thresholds by 18%, but again, robust contractions were still evoked by stimulation at volumes below the distension-evoked threshold. These results indicate that sympathetic mechanisms contribute to establishing the volume dependence of reflex contractions but are not critical to the excitatory pudendal to bladder reflex. A strong correlation between the magnitude of stimulation-evoked bladder contractions and bladder volume supports that convergence of pelvic afferents and pudendal afferents is responsible for bladder excitation evoked by pudendal afferents. Further, abolition of stimulation-evoked bladder contractions following administration of hexamethonium bromide confirmed that contractions were generated by pelvic efferent activation via the pelvic ganglion. These findings indicate that pudendal afferent stimulation evokes bladder contractions through convergence with pelvic afferents to increase pelvic efferent activity. PMID:21068196

10 CFR 961.11 - Text of the contract.

Code of Federal Regulations, 2010 CFR

2010-01-01

... requires permanent isolation. 13. The term electricity (kilowatt hours) generated and sold means gross...-type documents or computer software (including computer programs, computer software data bases, and...

Telescopic Imaging of Heater-Induced Airglow at HAARP

DTIC Science & Technology

2007-01-01

03-01-2007 Final1 10-09-2003 - 10-09-2006 4. TITLE AND SUBTITLE Ba. CONTRACT NUMBER Telescopic Imaging of Heater-Induced Airglow at HAARP N00014-03-1... HAARP to optically measure fine structure in the ionosphere and to study airglow sources. In the presence of aurora and a strong blanketing E layer... HAARP was modulated at intervals of several seconds. For several cycles, small bright airglow spots were observed whenever HAARP was on. These spots

Novel Tiltmeter for Monitoring Angle Shift In Incident Waves

DTIC Science & Technology

2008-12-01

40th Annual Precise Time and Time Interval (PTTI) Meeting 559   NOVEL TILTMETER FOR MONITORING ANGLE SHIFT IN INCIDENT WAVES S... Tiltmeter For Monitoring Angle Shift In Incident Waves 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...up, any angle change of the incident beam ’θ results in a change of the intensity transmission of the resonator.     A NOVEL ANGLE TILTMETER

COSMO-RS analysis on mixing properties obtained for the systems 1-butyl-X-methylpyridinium tetrafluoroborate [X = 2,3,4] and 1,ω-dibromoalkanes [ω = 1-6].

PubMed

Navas, Ana; Ortega, Juan; Palomar, José; Díaz, Carlos; Vreekamp, Remko

2011-05-07

A theoretical-experimental study for a set of 18 binary systems comprised of [bXmpy][BF(4)] (X=2-4) + 1,ω-Br(CH(2))(v)Br (v =ω=1-6) at a temperature of 298.15 K is presented. The solubility curves are determined for each binary system, establishing the intervals of measurement for the excess properties, H(E)(m) and V(E)(m). These properties are then determined for those systems that present a miscibility zone. Binary systems containing 1,ω-dibromoalkanes with ω=5,6 present reduced solubility intervals at the temperature of 298.15 K. However, the mixtures with 1,1-dibromomethane were totally miscible with the three isomers of 1-butyl-X-methylpyridinium tetrafluoroborate. Mixtures with dibromomethane present H(E)(m) <0, whereas H(E)(m) >0 for the other binary systems. Sigmoidal curves were observed for the V(E)(m) describing expansion and contraction processes for all the systems, except for the mixtures of [b2mpy][BF(4)] with the smaller dibromoalkanes, which present contraction effects. The COSMO-RS methodology was used to estimate the solubilities and the intermolecular interaction energies, giving an acceptable explanation of the behavioral structure of pure compounds and solutions. This journal is © the Owner Societies 2011

The Effectiveness of FES-Evoked EMG Potentials to Assess Muscle Force and Fatigue in Individuals with Spinal Cord Injury

PubMed Central

Ibitoye, Morufu Olusola; Estigoni, Eduardo H.; Hamzaid, Nur Azah; Wahab, Ahmad Khairi Abdul; Davis, Glen M.

2014-01-01

The evoked electromyographic signal (eEMG) potential is the standard index used to monitor both electrical changes within the motor unit during muscular activity and the electrical patterns during evoked contraction. However, technical and physiological limitations often preclude the acquisition and analysis of the signal especially during functional electrical stimulation (FES)-evoked contractions. Hence, an accurate quantification of the relationship between the eEMG potential and FES-evoked muscle response remains elusive and continues to attract the attention of researchers due to its potential application in the fields of biomechanics, muscle physiology, and rehabilitation science. We conducted a systematic review to examine the effectiveness of eEMG potentials to assess muscle force and fatigue, particularly as a biofeedback descriptor of FES-evoked contractions in individuals with spinal cord injury. At the outset, 2867 citations were identified and, finally, fifty-nine trials met the inclusion criteria. Four hypotheses were proposed and evaluated to inform this review. The results showed that eEMG is effective at quantifying muscle force and fatigue during isometric contraction, but may not be effective during dynamic contractions including cycling and stepping. Positive correlation of up to r = 0.90 (p < 0.05) between the decline in the peak-to-peak amplitude of the eEMG and the decline in the force output during fatiguing isometric contractions has been reported. In the available prediction models, the performance index of the eEMG signal to estimate the generated muscle force ranged from 3.8% to 34% for 18 s to 70 s ahead of the actual muscle force generation. The strength and inherent limitations of the eEMG signal to assess muscle force and fatigue were evident from our findings with implications in clinical management of spinal cord injury (SCI) population. PMID:25025551

In-Vivo Measurement of Muscle Tension: Dynamic Properties of the MC Sensor during Isometric Muscle Contraction

PubMed Central

Đorđević, Srđan; Tomažič, Sašo; Narici, Marco; Pišot, Rado; Meglič, Andrej

2014-01-01

Skeletal muscle is the largest tissue structure in our body and plays an essential role for producing motion through integrated action with bones, tendons, ligaments and joints, for stabilizing body position, for generation of heat through cell respiration and for blood glucose disposal. A key function of skeletal muscle is force generation. Non-invasive and selective measurement of muscle contraction force in the field and in clinical settings has always been challenging. The aim of our work has been to develop a sensor that can overcome these difficulties and therefore enable measurement of muscle force during different contraction conditions. In this study, we tested the mechanical properties of a “Muscle Contraction” (MC) sensor during isometric muscle contraction in different length/tension conditions. The MC sensor is attached so that it indents the skin overlying a muscle group and detects varying degrees of tension during muscular contraction. We compared MC sensor readings over the biceps brachii (BB) muscle to dynamometric measurements of force of elbow flexion, together with recordings of surface EMG signal of BB during isometric contractions at 15° and 90° of elbow flexion. Statistical correlation between MC signal and force was very high at 15° (r = 0.976) and 90° (r = 0.966) across the complete time domain. Normalized SD or σN = σ/max(FMC) was used as a measure of linearity of MC signal and elbow flexion force in dynamic conditions. The average was 8.24% for an elbow angle of 90° and 10.01% for an elbow of angle 15°, which indicates high linearity and good dynamic properties of MC sensor signal when compared to elbow flexion force. The next step of testing MC sensor potential will be to measure tension of muscle-tendon complex in conditions when length and tension change simultaneously during human motion. PMID:25256114

Optimal strategies for electric energy contract decision making

NASA Astrophysics Data System (ADS)

Song, Haili

2000-10-01

The power industry restructuring in various countries in recent years has created an environment where trading of electric energy is conducted in a market environment. In such an environment, electric power companies compete for the market share through spot and bilateral markets. Being profit driven, electric power companies need to make decisions on spot market bidding, contract evaluation, and risk management. New methods and software tools are required to meet these upcoming needs. In this research, bidding strategy and contract pricing are studied from a market participant's viewpoint; new methods are developed to guide a market participant in spot and bilateral market operation. A supplier's spot market bidding decision is studied. Stochastic optimization is formulated to calculate a supplier's optimal bids in a single time period. This decision making problem is also formulated as a Markov Decision Process. All the competitors are represented by their bidding parameters with corresponding probabilities. A systematic method is developed to calculate transition probabilities and rewards. The optimal strategy is calculated to maximize the expected reward over a planning horizon. Besides the spot market, a power producer can also trade in the bilateral markets. Bidding strategies in a bilateral market are studied with game theory techniques. Necessary and sufficient conditions of Nash Equilibrium (NE) bidding strategy are derived based on the generators' cost and the loads' willingness to pay. The study shows that in any NE, market efficiency is achieved. Furthermore, all Nash equilibria are revenue equivalent for the generators. The pricing of "Flexible" contracts, which allow delivery flexibility over a period of time with a fixed total amount of electricity to be delivered, is analyzed based on the no-arbitrage pricing principle. The proposed algorithm calculates the price based on the optimality condition of the stochastic optimization formulation. Simulation examples illustrate the tradeoffs between prices and scheduling flexibility. Spot bidding and contract pricing are not independent decision processes. The interaction between spot bidding and contract evaluation is demonstrated with game theory equilibrium model and market simulation results. It leads to the conclusion that a market participant's contract decision making needs to be further investigated as an integrated optimization formulation.

Interval-level measurement with visual analogue scales in Internet-based research: VAS Generator.

PubMed

Reips, Ulf-Dietrich; Funke, Frederik

2008-08-01

The present article describes VAS Generator (www.vasgenerator.net), a free Web service for creating a wide range of visual analogue scales that can be used as measurement devices in Web surveys and Web experimentation, as well as for local computerized assessment. A step-by-step example for creating and implementing a visual analogue scale with visual feedback is given. VAS Generator and the scales it generates work independently of platforms and use the underlying languages HTML and JavaScript. Results from a validation study with 355 participants are reported and show that the scales generated with VAS Generator approximate an interval-scale level. In light of previous research on visual analogue versus categorical (e.g., radio button) scales in Internet-based research, we conclude that categorical scales only reach ordinal-scale level, and thus visual analogue scales are to be preferred whenever possible.

The anamorphic universe

NASA Astrophysics Data System (ADS)

Ijjas, Anna; Steinhardt, Paul J.

2015-10-01

We introduce ``anamorphic'' cosmology, an approach for explaining the smoothness and flatness of the universe on large scales and the generation of a nearly scale-invariant spectrum of adiabatic density perturbations. The defining feature is a smoothing phase that acts like a contracting universe based on some Weyl frame-invariant criteria and an expanding universe based on other frame-invariant criteria. An advantage of the contracting aspects is that it is possible to avoid the multiverse and measure problems that arise in inflationary models. Unlike ekpyrotic models, anamorphic models can be constructed using only a single field and can generate a nearly scale-invariant spectrum of tensor perturbations. Anamorphic models also differ from pre-big bang and matter bounce models that do not explain the smoothness. We present some examples of cosmological models that incorporate an anamorphic smoothing phase.

Water Processor and Oxygen Generation Assembly

NASA Technical Reports Server (NTRS)

Bedard, John

1997-01-01

This report documents the results of the tasks which initiated efforts on design issues relating to the Water Processor (WP) and the Oxygen Generation Assembly (OGA) Flight Hardware for the International Space Station. This report fulfills the Statement of Work deliverables requirement for contract H-29387D. The following lists the tasks required by contract H-29387D: (1) HSSSI shall coordinate a detailed review of WP/OGA Flight Hardware program requirements with personnel from MSFC to identify requirements that can be eliminated without affecting the technical integrity of the WP/OGA Hardware; (2) HSSSI shall conduct the technical interchanges with personnel from MSFC to resolve design issues related to WP/OGA Flight Hardware; (3) HSSSI will initiate discussions with Zellwegger Analytics, Inc. to address design issues related to WP and PCWQM interfaces.

Electrocardiogram reference intervals for clinically normal wild-born chimpanzees (Pan troglodytes).

PubMed

Atencia, Rebeca; Revuelta, Luis; Somauroo, John D; Shave, Robert E

2015-08-01

To generate reference intervals for ECG variables in clinically normal chimpanzees (Pan troglodytes). 100 clinically normal (51 young [< 10 years old] and 49 adult [≥ 10 years old]) wild-born chimpanzees. Electrocardiograms collected between 2009 and 2013 at the Tchimpounga Chimpanzee Rehabilitation Centre were assessed to determine heart rate, PR interval, QRS duration, QT interval, QRS axis, P axis, and T axis. Electrocardiographic characteristics for left ventricular hypertrophy (LVH) and morphology of the ST segment, T wave, and QRS complex were identified. Reference intervals for young and old animals were calculated as mean ± 1.96•SD for normally distributed data and as 5th to 95th percentiles for data not normally distributed. Differences between age groups were assessed by use of unpaired Student t tests. RESULTS Reference intervals were generated for young and adult wild-born chimpanzees. Most animals had sinus rhythm with small or normal P wave morphology; 24 of 51 (47%) young chimpanzees and 30 of 49 (61%) adult chimpanzees had evidence of LVH as determined on the basis of criteria for humans. Cardiac disease has been implicated as the major cause of death in captive chimpanzees. Species-specific ECG reference intervals for chimpanzees may aid in the diagnosis and treatment of animals with, or at risk of developing, heart disease. Chimpanzees with ECG characteristics outside of these intervals should be considered for follow-up assessment and regular cardiac monitoring.

Three-dimensional hysteresis compensation enhances accuracy of robotic artificial muscles

NASA Astrophysics Data System (ADS)

Zhang, Jun; Simeonov, Anthony; Yip, Michael C.

2018-03-01

Robotic artificial muscles are compliant and can generate straight contractions. They are increasingly popular as driving mechanisms for robotic systems. However, their strain and tension force often vary simultaneously under varying loads and inputs, resulting in three-dimensional hysteretic relationships. The three-dimensional hysteresis in robotic artificial muscles poses difficulties in estimating how they work and how to make them perform designed motions. This study proposes an approach to driving robotic artificial muscles to generate designed motions and forces by modeling and compensating for their three-dimensional hysteresis. The proposed scheme captures the nonlinearity by embedding two hysteresis models. The effectiveness of the model is confirmed by testing three popular robotic artificial muscles. Inverting the proposed model allows us to compensate for the hysteresis among temperature surrogate, contraction length, and tension force of a shape memory alloy (SMA) actuator. Feedforward control of an SMA-actuated robotic bicep is demonstrated. This study can be generalized to other robotic artificial muscles, thus enabling muscle-powered machines to generate desired motions.

An Artificial Particle Precipitation Technique Using HAARP-Generated VLF Waves

DTIC Science & Technology

2006-11-02

AFRL-VS-HA-TR-2007-1021 An Artificial Particle Precipitation Technique Using HAARP -Generated VLF Waves O o o r- Q M. J. Kosch T. Pedersen J...Artificial Particle Precipitation Technique Using HAARP Generated VLF Waves. 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62101F...model. The frequency-time modulated VLF wave patterns have been successfully implemented at the HAARP ionospheric modification facility in Alaska

Anisotropic Grid Generation

DTIC Science & Technology

2016-03-24

AFRL-AFOSR-VA-TR-2016-0129 ANISOTROPIC GRID GENERATION | Deliverables Daniel Sievenpiper UNIVERSITY OF CALIFORNIA SAN DIEGO Final Report 03/24/2016...ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY) 12-03-2016 2 . REPORT TYPE Final report 3. DATES COVERED (From - To) 15-12-2012 - 14-12-2015 4. TITLE AND...SUBTITLE Anisotropic Grid Generation 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-13-1-0014 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Daniel

Closed Loop Control of Oxygen Delivery and Oxygen Generation

DTIC Science & Technology

2017-08-01

AFRL-SA-WP-SR-2017-0024 Closed Loop Control of Oxygen Delivery and Oxygen Generation Dr. Jay Johannigman1, Richard Branson1...for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO...TITLE AND SUBTITLE Closed Loop Control of Oxygen Delivery and Oxygen Generation 5a. CONTRACT NUMBER FA8650-10-2-6140 5b. GRANT NUMBER

The Sortie-Generation Model System. Volume 5. Maintenance Subsystem

DTIC Science & Technology

1981-09-01

Compuger RoanutI f and moidel 11, Computer operatinS system 17, Proorammino largualviso IS. Numlier of .ugic proltsm Hoewl -3 CSCobol 600 stuscomentm...THE SORTIE-GENERATION MODEL SYSTEM OC’ VOLUME V MAINTENANCE SUBSYSTEM September 1981 Robert S. Greenberg 05$ Prepared pursuant to Department of...Generation Model System Volume V Maintenance Subsystem 6. PERFORMING ORG. REPORT NUMBER LMI Task- L102 7. AUTHOR(a) 8. CONTRACT OR GRANT NUMBER(a

Electronic circuit delivers pulse of high interval stability

NASA Technical Reports Server (NTRS)

Fisher, B.

1966-01-01

Circuit generates a pulse of high interval stability with a complexity level considerably below systems of comparable stability. This circuit is being used as a linear frequency discriminator in the signal conditioner of the Apollo command module.

2006 Pacific Northwest Loads and Resources Study.

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

United States. Bonneville Power Administration.

2006-03-01

The Pacific Northwest Loads and Resources Study (White Book), which is published annually by the Bonneville Power Administration (BPA), establishes one of the planning bases for supplying electricity to customers. The White Book contains projections of regional and Federal system load and resource capabilities, along with relevant definitions and explanations. The White Book also contains information obtained from formalized resource planning reports and data submittals including those from individual utilities, the Northwest Power and Conservation Council (Council), and the Pacific Northwest Utilities Conference Committee (PNUCC). The White Book is not an operational planning guide, nor is it used for determiningmore » BPA revenues, although the database that generates the data for the White Book analysis contributes to the development of BPA's inventory and ratemaking processes. Operation of the Federal Columbia River Power System (FCRPS) is based on a set of criteria different from that used for resource planning decisions. Operational planning is dependent upon real-time or near-term knowledge of system conditions that include expectations of river flows and runoff, market opportunities, availability of reservoir storage, energy exchanges, and other factors affecting the dynamics of operating a power system. The load resource balance of both the Federal system and the region is determined by comparing resource availability to an expected level of total retail electricity consumption. Resources include projected energy capability plus contract purchases. Loads include a forecast of retail obligations plus contract obligations. Surplus energy is available when resources are greater than loads. This surplus energy could be marketed to increase revenues. Energy deficits occur when resources are less than loads. These energy deficits will be met by any combination of the following: better-than-critical water conditions, demand-side management and conservation programs, permanent loss of loads due to economic conditions or closures, additional contract purchases, and/or the addition of new generating resources. This study incorporates information on Pacific Northwest (PNW) regional retail loads, contract obligations, and contract resources. This loads and resources analysis simulates the operation of the power system in the PNW. The simulated hydro operation incorporates plant characteristics, streamflows, and non-power requirements from the current Pacific Northwest Coordination Agreement (PNCA). Additional resource capability estimates were provided by BPA, PNW Federal agency, public agency, cooperative, U.S. Bureau of Reclamation (USBR), and investor-owned utility (IOU) customers furnished through annual PNUCC data submittals for 2005 and/or direct submittals to BPA. The 2006 White Book is presented in two documents: (1) this summary document of Federal system and PNW region loads and resources, and (2) a technical appendix which presents regional loads, grouped by major PNW utility categories, and detailed contract and resource information. The technical appendix is available only in electronic form. Individual customer information for marketer contracts is not detailed due to confidentiality agreements. The 2006 White Book analysis updates the 2004 White Book. This analysis shows projections of the Federal system and region's yearly average annual energy consumption and resource availability for the study period, OY 2007-2016. The study also presents projections of Federal system and region expected 1-hour monthly peak demand, monthly energy demand, monthly 1-hour peak generating capability, and monthly energy generation for OY 2007, 2011, and 2016. BPA is investigating a new approach in capacity planning depicting the monthly Federal system 120-hour peak generating capability and 120-hour peak surplus/deficit for OY 2007, 2011, and 2016. This document analyzes the PNW's projected loads and available generating resources in two parts: (1) the loads and resources of the Federal system, for which BPA is the marketing agency; and (2) the larger PNW regional power system loads and resources that include the Federal system as well other PNW entities.« less

Muscular co-contraction during walking and landing from a jump: comparison between genders and influence of activity level.

PubMed

da Fonseca, Sergio Teixeira; Vaz, Daniela Virgínia; de Aquino, Cecília Ferreira; Brício, Rachel Soares

2006-06-01

Women have higher rates of knee ligament injury than men. Co-contraction of knee muscles is proposed to be an important mechanism to protect the joint from injuries. Females have lower co-contraction levels when compared to males. Exploratory, cross-sectional design. Thirty-six men and women equally divided into four groups according to gender and activity level (sedentary and athletic) were compared in relation to vastus lateralis and biceps femoris co-contraction before heel strike during level walking and before floor contact during landing from a jump. Muscular co-contraction was assessed by surface electromyography. Correlations between co-contraction and ligament laxity, extensor and flexor work, and flexion/extension torque ratio were also analyzed. No differences between genders were found in the studied situations (p0.381). During walking, co-contraction was greater in sedentary women compared to athletic women (p=0.002). A moderate inverse correlation was found between co-contraction during walking and women extensor (r=-0.613; p=0.007) and flexor (r=-0.575; p=0.012) work. During landing from a jump, no variables correlated to co-contraction in any of the groups tested (r0.477; p0.061). Co-contraction levels were not different between genders. Results suggest that women compensate strength deficits by means of increasing activation levels, possibly to generate adequate joint stiffness to meet stabilization demands. However, this is not evident in a more stressful activity like landing from a jump. This study contributes to a better understanding of the factors related to joint protection in females, who are at a greater risk of ligament injuries.

HANFORD SITE RIVER CORRIDOR CLEANUP

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

BAZZELL, K.D.

2006-02-01

In 2005, the US Department of Energy (DOE) launched the third generation of closure contracts, including the River Corridor Closure (RCC) Contract at Hanford. Over the past decade, significant progress has been made on cleaning up the river shore that bordes Hanford. However, the most important cleanup challenges lie ahead. In March 2005, DOE awarded the Hanford River Corridor Closure Contract to Washington Closure Hanford (WCH), a limited liability company owned by Washington Group International, Bechtel National and CH2M HILL. It is a single-purpose company whose goal is to safely and efficiently accelerate cleanup in the 544 km{sup 2} Hanfordmore » river corridor and reduce or eliminate future obligations to DOE for maintaining long-term stewardship over the site. The RCC Contract is a cost-plus-incentive-fee closure contract, which incentivizes the contractor to reduce cost and accelerate the schedule. At $1.9 billion and seven years, WCH has accelerated cleaning up Hanford's river corridor significantly compared to the $3.2 billion and 10 years originally estimated by the US Army Corps of Engineers. Predictable funding is one of the key features of the new contract, with funding set by contract at $183 million in fiscal year (FY) 2006 and peaking at $387 million in FY2012. Another feature of the contract allows for Washington Closure to perform up to 40% of the value of the contract and subcontract the balance. One of the major challenges in the next few years will be to identify and qualify sufficient subcontractors to meet the goal.« less

Differences in muscle activation patterns during pelvic floor muscle contraction and Valsalva maneuver.

PubMed

Thompson, Judith A; O'Sullivan, Peter B; Briffa, N Kathryn; Neumann, Patricia

2006-01-01

To investigate the different muscle activation patterns around the abdomino-pelvic cavity in continent women and their effect on pressure generation during a correct pelvic floor muscle (PFM) contraction and a Valsalva maneuver. Thirteen continent women were assessed. Abdominal, chest wall, and PFM activity and vaginal and intra-abdominal pressure (IAP), were recorded during two tasks: PFM contraction and Valsalva whilst bladder base position was monitored on trans-abdominal ultrasound. A correct PFM contraction was defined as one that resulted in bladder base elevation and a Valsalva resulted in bladder base depression. Comparison of the mean of the normalized EMG activity of all the individual muscle groups was significantly different between PFM contraction and Valsalva (P = 0.04). During a correct PFM contraction, the PFM were more active than during Valsalva (P = 0.001). During Valsalva, all the abdominal muscles (IO (P = 0.006), EO (P < 0.001), RA (P = 0.011)), and the chest wall (P < 0.001) were more active than during PFM contraction. The change in IAP was greater during Valsalva (P = 0.001) but there was no difference in the change in vaginal pressure between PFM contraction and Valsalva (P = 0.971). This study demonstrates a difference in muscle activation patterns between a correct PFM contraction and Valsalva maneuver. It is important to include assessment of the abdominal wall, chest wall, and respiration in the clinical evaluation of women performing PFM exercises as abdominal wall bracing combined with an increase in chest wall activity may cause rises in IAP and PFM descent. (c) 2005 Wiley-Liss, Inc.

Skeletal Muscle Remodeling in Response to Eccentric vs. Concentric Loading: Morphological, Molecular, and Metabolic Adaptations

PubMed Central

Franchi, Martino V.; Reeves, Neil D.; Narici, Marco V.

2017-01-01

Skeletal muscle contracts either by shortening or lengthening (concentrically or eccentrically, respectively); however, the two contractions substantially differ from one another in terms of mechanisms of force generation, maximum force production and energy cost. It is generally known that eccentric actions generate greater force than isometric and concentric contractions and at a lower metabolic cost. Hence, by virtue of the greater mechanical loading involved in active lengthening, eccentric resistance training (ECC RT) is assumed to produce greater hypertrophy than concentric resistance training (CON RT). Nonetheless, prevalence of either ECC RT or CON RT in inducing gains in muscle mass is still an open issue, with some studies reporting greater hypertrophy with eccentric, some with concentric and some with similar hypertrophy within both training modes. Recent observations suggest that such hypertrophic responses to lengthening vs. shortening contractions are achieved by different adaptations in muscle architecture. Whilst the changes in muscle protein synthesis in response to acute and chronic concentric and eccentric exercise bouts seem very similar, the molecular mechanisms regulating the myogenic adaptations to the two distinct loading stimuli are still incompletely understood. Thus, the present review aims to, (a) critically discuss the literature on the contribution of eccentric vs. concentric loading to muscular hypertrophy and structural remodeling, and, (b) clarify the molecular mechanisms that may regulate such adaptations. We conclude that, when matched for either maximum load or work, similar increase in muscle size is found between ECC and CON RT. However, such hypertrophic changes appear to be achieved through distinct structural adaptations, which may be regulated by different myogenic and molecular responses observed between lengthening and shortening contractions. PMID:28725197

Force generation in bacteria without nucleotide-dependent bending of cytoskeletal filaments.

PubMed

Ghosh, Biplab; Sain, Anirban

2011-05-01

Binary cell division in bacteria occurs via the formation and subsequent contraction of a polymeric ring, the so-called Z ring, at the middle of the cell. This ring is made of filamenting temperature-sensitive Z (FtsZ) proteins and it shrinks in radius to generate a contractile radial force on the cell membrane. Although a few models have been proposed, the ring contraction mechanism still remains a mystery. The models rely on various physical properties of the FtsZ filaments, some of which have been verified through in vitro experiments and some of which remain unclear. A feature common to all these models is the hydrolysis-driven transition of FtsZ filaments from straight to curved conformations. While the intrinsic curvature of FtsZ filaments has been experimentally established beyond doubt, evidence has been mounting against the existence of any transition between the straight FtsZ-GTP and the curved FtsZ-GDP conformations. Preliminary results from our earlier work [B. Ghosh and A. Sain, Phys. Rev. Lett. 101, 178101 (2008)] indicated that hydrolysis-induced bending is not necessary for Z-ring contraction. Since then many new experimental observations have been reported on this subject and in view of these here we argue that our model appears even more plausible than before. In addition, we have explored more realistic features, such as how the length distribution of FtsZ filaments in the cytoplasm may influence the contraction dynamics, and we have also demonstrated that the Z ring retains approximately the same number of monomers, although not the same monomers, during the course of contraction as reported by fluorescence experiments.

Chronic ethanol consumption induces erectile dysfunction: Role of oxidative stress.

PubMed

Muniz, Jaqueline J; Leite, Letícia N; De Martinis, Bruno S; Carneiro, Fernando S; Tirapelli, Carlos R

2015-11-15

Investigate the effects of chronic ethanol consumption on erectile function and on the corpus cavernosum (CC) reactivity to endothelin-1 (ET-1). Male Wistar rats were treated with ethanol (20% v/v) for six weeks. Ethanol-treated rats showed impaired erectile function represented by decreased intracavernosal pressure/mean arterial pressure (ICP/MAP) responses. Ethanol consumption increased the contractile response induced by ET-1 in the isolated CC. Tiron increased ET-1-induced contraction in CC from control and ethanol-treated rats. No differences in the maximal contraction to ET-1 were observed after incubation of CC with PEG-catalase. SC560 and SC236 increased ET-1-induced contraction in CC from ethanol-treated rats. Y27632 reduced the contraction induced by ET-1 in CC from control and ethanol-treated rats. Ethanol increased plasma TBARS, superoxide anion (O2(-)) levels and intracellular reactive oxygen species (ROS) generation in the rat CC. Reduced hydrogen peroxide (H2O2) levels in CC and increased catalase (CAT) activity in plasma and CC were detected after treatment with ethanol. Ethanol decreased superoxide dismutase (SOD) activity in the rat CC. Increased expression of COX-1 was observed in CC from ethanol-treated rats. Treatment with ethanol decreased COX-2 expression but did not alter the expression of Nox1, RhoA and p-RhoA (ser(188)) in the rat CC. The major new findings of our study are that ethanol consumption induces erectile dysfunction (ED) and increases the contraction induced by ET-1 in the rat CC by a mechanism that involves decreased generation of H2O2 and vasodilator prostanoids as well as increased activation of the RhoA/Rho-kinase pathway. Copyright © 2015 Elsevier Inc. All rights reserved.

A multi-scale cardiovascular system model can account for the load-dependence of the end-systolic pressure-volume relationship

PubMed Central

2013-01-01

Background The end-systolic pressure-volume relationship is often considered as a load-independent property of the heart and, for this reason, is widely used as an index of ventricular contractility. However, many criticisms have been expressed against this index and the underlying time-varying elastance theory: first, it does not consider the phenomena underlying contraction and second, the end-systolic pressure volume relationship has been experimentally shown to be load-dependent. Methods In place of the time-varying elastance theory, a microscopic model of sarcomere contraction is used to infer the pressure generated by the contraction of the left ventricle, considered as a spherical assembling of sarcomere units. The left ventricle model is inserted into a closed-loop model of the cardiovascular system. Finally, parameters of the modified cardiovascular system model are identified to reproduce the hemodynamics of a normal dog. Results Experiments that have proven the limitations of the time-varying elastance theory are reproduced with our model: (1) preload reductions, (2) afterload increases, (3) the same experiments with increased ventricular contractility, (4) isovolumic contractions and (5) flow-clamps. All experiments simulated with the model generate different end-systolic pressure-volume relationships, showing that this relationship is actually load-dependent. Furthermore, we show that the results of our simulations are in good agreement with experiments. Conclusions We implemented a multi-scale model of the cardiovascular system, in which ventricular contraction is described by a detailed sarcomere model. Using this model, we successfully reproduced a number of experiments that have shown the failing points of the time-varying elastance theory. In particular, the developed multi-scale model of the cardiovascular system can capture the load-dependence of the end-systolic pressure-volume relationship. PMID:23363818

Superconductor Armature Winding for High Performance Electrical Machines

DTIC Science & Technology

2016-12-05

Vol. 3, pp.489-507 [Kalsi1] S. S. Kalsi, ‘Superconducting Wind Turbine Generator Employing MgB2 Windings Both on Rotor and Stator’, IEEE Trans. on...Contract  Number:  N00014-­‐14-­‐1-­‐0272   Contract  Title:  Superconductor  armature   winding  for  high  performance  electrical...an all-superconducting machine. Superconductor armature windings in electrical machines bring many design challenges that need to be addressed en

Precipitating Auroral Electron Flux Characteristics Based on UV Data Obtained by the AIRS Experiment Onboard the Polar BEAR Satellite

DTIC Science & Technology

1992-03-01

approved for publication. RICHARD EASTES DAVID ANDERSON Contract Manager Branch Chief "" K. VICKERY Division Director This document has been reviewed by...Contract Manager: Richard Eastes/GPIM 11. SUPPLEMENTARY NOTES 12a. DISTRIBUTION /AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE Approved for public...system within this band ( Vallance Jones, 1974) 4.2 Model atmosphere MSIS86 (Hedin, 1987) was used to generate the model atmospheres for our analysis of

It's all in the timing: modeling isovolumic contraction through development and disease with a dynamic dual electromechanical bioreactor system.

PubMed

Morgan, Kathy Ye; Black, Lauren Deems

2014-01-01

This commentary discusses the rationale behind our recently reported work entitled "Mimicking isovolumic contraction with combined electromechanical stimulation improves the development of engineered cardiac constructs," introduces new data supporting our hypothesis, and discusses future applications of our bioreactor system. The ability to stimulate engineered cardiac tissue in a bioreactor system that combines both electrical and mechanical stimulation offers a unique opportunity to simulate the appropriate dynamics between stretch and contraction and model isovolumic contraction in vitro. Our previous study demonstrated that combined electromechanical stimulation that simulated the timing of isovolumic contraction in healthy tissue improved force generation via increased contractile and calcium handling protein expression and improved hypertrophic pathway activation. In new data presented here, we further demonstrate that modification of the timing between electrical and mechanical stimulation to mimic a non-physiological process negatively impacts the functionality of the engineered constructs. We close by exploring the various disease states that have altered timing between the electrical and mechanical stimulation signals as potential future directions for the use of this system.

Collective hydrodynamic communication through ultra-fast contractions

NASA Astrophysics Data System (ADS)

Bhamla, Saad; Mathijssen, Arnold; Prakash, Manu

2017-11-01

The biophysical relationships between physiological sensors and actuators were fundamental to the development of early life forms, as responding to external stimuli promptly is key to survival. We study an unusual protist Spirostomum ambiguum, a single-celled organism that can grow up to 4mm in size, visible to the naked eye, as a model system for impulsive systems. Coiling its cytoskeleton, this ciliate can contract its long body within milliseconds, one of the fastest accelerations known in cell biology. We demonstrate that these rapid contractions generate long-ranged vortex flows that can trigger other cells to contract, repeatedly, which collectively leads to an ultra-fast hydrodynamic signal transduction across a colony that moves hundreds of times faster than the swimming speed. By combining high-speed PIV experiments and analytical modelling we determine the critical rheosensitivity required to sustain these signal waves. Whereas the biological motive is not fully understood, contractions are known to release toxins from membrane-bound extrusomes, thus we hypothesize that synchronised discharges could facilitate the repulsion of large-scale predators cooperatively. Please also see our other talk ``Rheosensing by impulsive cells at intermediate Reynolds numbers''.

An Implantable Extracardiac Soft Robotic Device for the Failing Heart: Mechanical Coupling and Synchronization.

PubMed

Payne, Christopher J; Wamala, Isaac; Abah, Colette; Thalhofer, Thomas; Saeed, Mossab; Bautista-Salinas, Daniel; Horvath, Markus A; Vasilyev, Nikolay V; Roche, Ellen T; Pigula, Frank A; Walsh, Conor J

2017-09-01

Soft robotic devices have significant potential for medical device applications that warrant safe synergistic interaction with humans. This article describes the optimization of an implantable soft robotic system for heart failure whereby soft actuators wrapped around the ventricles are programmed to contract and relax in synchrony with the beating heart. Elastic elements integrated into the soft actuators provide recoiling function so as to aid refilling during the diastolic phase of the cardiac cycle. Improved synchronization with the biological system is achieved by incorporating the native ventricular pressure into the control system to trigger assistance and synchronize the device with the heart. A three-state electro-pneumatic valve configuration allows the actuators to contract at different rates to vary contraction patterns. An in vivo study was performed to test three hypotheses relating to mechanical coupling and temporal synchronization of the actuators and heart. First, that adhesion of the actuators to the ventricles improves cardiac output. Second, that there is a contraction-relaxation ratio of the actuators which generates optimal cardiac output. Third, that the rate of actuator contraction is a factor in cardiac output.

A view from the terrace; ice-sheet dynamics during the Eocene Oligocene Transition climate tipping point

NASA Astrophysics Data System (ADS)

Scher, Howie; Bohaty, Steven; Huck, Claire

2017-04-01

Glaciation of Antarctica was the pièce de résistance of the shift in global climate that took place during the Eocene Oligocene Transition (EOT; ca. 34 Ma). The timing and progression of ice-sheet development is constrained by benthic foraminiferal d18O records and geochemical proxies for continental weathering from deep-sea sediment cores. The terrace interval is the roughly 500 kyr interval after the precursor glaciation at 34.2 Ma, when ice-sheet expansion reached a short-lived plateau prior to the coalescence of a continent-scale ice sheet at 33.7 Ma. The terrace interval appears to be the tipping point between greenhouse and icehouse climate states, however ice-sheet dynamics are poorly understood during this crucial time. We present evidence for rapid changes in the Nd isotopic composition of bottom waters bathing a sediment core on Maud Rise (ODP Site 689) during the terrace interval of the EOT. Three distinct excursions toward less radiogenic eNd values suggest either 1) changes in the flux of Antarctic weathering products into the Weddell Sea and/or 2) pulses of deep water production that brought shelf waters with the Antarctic Nd isotope fingerprint into contact with Maud Rise. Both interpretations support a scenario of expansion and contraction of the Antarctic ice sheet during the terrace interval.

Comparison of timing and force control of foot tapping between elderly and young subjects.

PubMed

Takimoto, Koji; Takebayashi, Hideaki; Miyamoto, Kenzo; Takuma, Yutaka; Inoue, Yoshikazu; Miyamoto, Shoko; Okabe, Takao; Okuda, Takahiro; Kaba, Hideto

2016-06-01

[Purpose] To examine the ability of young and elderly individuals to control the timing and force of periodic sequential foot tapping. [Subjects and Methods] Participants were 10 young (age, 22.1 ± 4.3 years) and 10 elderly individuals (74.8 ± 6.7 years) who were healthy and active. The foot tapping task consisted of practice (stimulus-synchronized tapping with visual feedback) and recall trials (self-paced tapping without visual feedback), periodically performed in this order, at 500-, 1,000-, and 2,000-ms target interstimulus-onset intervals, with a target force of 20% maximum voluntary contraction of the ankle plantar-flexor muscle. [Results] The coefficients of variation of force and intertap interval, used for quantifying the steadiness of the trials, were significantly greater in the elderly than in the young individuals. At the 500-ms interstimulus-onset interval, age-related effects were observed on the normalized mean absolute error of force, which was used to quantify the accuracy of the trials. The coefficients of variation of intertap interval for elderly individuals were significantly greater in the practice than in the recall trials at the 500- and 1,000-ms interstimulus-onset intervals. [Conclusion] The elderly individuals exhibited greater force and timing variability than the young individuals and showed impaired visuomotor processing during foot tapping sequences.

Comparison of automated measurements of electrocardiographic intervals and durations by computer-based algorithms of digital electrocardiographs.

PubMed

Kligfield, Paul; Badilini, Fabio; Rowlandson, Ian; Xue, Joel; Clark, Elaine; Devine, Brian; Macfarlane, Peter; de Bie, Johan; Mortara, David; Babaeizadeh, Saeed; Gregg, Richard; Helfenbein, Eric D; Green, Cynthia L

2014-02-01

Automated measurements of electrocardiographic (ECG) intervals are widely used by clinicians for individual patient diagnosis and by investigators in population studies. We examined whether clinically significant systematic differences exist in ECG intervals measured by current generation digital electrocardiographs from different manufacturers and whether differences, if present, are dependent on the degree of abnormality of the selected ECGs. Measurements of RR interval, PR interval, QRS duration, and QT interval were made blindly by 4 major manufacturers of digital electrocardiographs used in the United States from 600 XML files of ECG tracings stored in the US FDA ECG warehouse and released for the purpose of this study by the Cardiac Safety Research Consortium. Included were 3 groups based on expected QT interval and degree of repolarization abnormality, comprising 200 ECGs each from (1) placebo or baseline study period in normal subjects during thorough QT studies, (2) peak moxifloxacin effect in otherwise normal subjects during thorough QT studies, and (3) patients with genotyped variants of congenital long QT syndrome (LQTS). Differences of means between manufacturers were generally small in the normal and moxifloxacin subjects, but in the LQTS patients, differences of means ranged from 2.0 to 14.0 ms for QRS duration and from 0.8 to 18.1 ms for the QT interval. Mean absolute differences between algorithms were similar for QRS duration and QT intervals in the normal and in the moxifloxacin subjects (mean ≤6 ms) but were significantly larger in patients with LQTS. Small but statistically significant group differences in mean interval and duration measurements and means of individual absolute differences exist among automated algorithms of widely used, current generation digital electrocardiographs. Measurement differences, including QRS duration and the QT interval, are greatest for the most abnormal ECGs. © 2014.

ICP-MS Data Validation

EPA Pesticide Factsheets

Document designed to offer data reviewers guidance in determining the validity ofanalytical data generated through the USEPA Contract Laboratory Program Statement ofWork (SOW) ISM01.X Inorganic Superfund Methods (Multi-Media, Multi-Concentration)

Keratinocyte cytoskeletal roles in cell sheet engineering

PubMed Central

2013-01-01

Background There is an increasing need to understand cell-cell interactions for cell and tissue engineering purposes, such as optimizing cell sheet constructs, as well as for examining adhesion defect diseases. For cell-sheet engineering, one major obstacle to sheet function is that cell sheets in suspension are fragile and, over time, will contract. While the role of the cytoskeleton in maintaining the structure and adhesion of cells cultured on a rigid substrate is well-characterized, a systematic examination of the role played by different components of the cytoskeleton in regulating cell sheet contraction and cohesion in the absence of a substrate has been lacking. Results In this study, keratinocytes were cultured until confluent and cell sheets were generated using dispase to remove the influence of the substrate. The effects of disrupting actin, microtubules or intermediate filaments on cell-cell interactions were assessed by measuring cell sheet cohesion and contraction. Keratin intermediate filament disruption caused comparable effects on cell sheet cohesion and contraction, when compared to actin or microtubule disruption. Interfering with actomyosin contraction demonstrated that interfering with cell contraction can also diminish cell cohesion. Conclusions All components of the cytoskeleton are involved in maintaining cell sheet cohesion and contraction, although not to the same extent. These findings demonstrate that substrate-free cell sheet biomechanical properties are dependent on the integrity of the cytoskeleton network. PMID:23442760

Testing to Characterize the Advanced Stirling Radioisotope Generator Engineering Unit

NASA Technical Reports Server (NTRS)

Lewandowski, Edward; Schreiber, Jeffrey

2010-01-01

The Advanced Stirling Radioisotope Generator (ASRG), a high efficiency generator, is being considered for space missions. Lockheed Martin designed and fabricated an engineering unit (EU), the ASRG EU, under contract to the Department of Energy. This unit is currently undergoing extended operation testing at the NASA Glenn Research Center to generate performance data and validate life and reliability predictions for the generator and the Stirling convertors. It has also undergone performance tests to characterize generator operation while varying control parameters and system inputs. This paper summarizes and explains test results in the context of designing operating strategies for the generator during a space mission and notes expected differences between the EU performance and future generators.

Effects of imatinib mesylate on the spontaneous activity generated by the guinea-pig prostate.

PubMed

Lam, Michelle; Dey, Anupa; Lang, Richard J; Exintaris, Betty

2013-08-01

What's known on the subject? and what does the study add?: Several studies have examined the functional role of tyrosine kinase receptors in the generation of spontaneous activity in various segments of the gastrointestinal and urogenital tracts through the application of its inhibitor, imatinib mesylate (Glivec®), but results are fairly inconsistent. This is the first study detailing the effects of imatinib mesylate on the spontaneous activity in the young and ageing prostate gland. As spontaneous electrical activity underlies the spontaneous rhythmic prostatic contractions that occur at rest, elucidating the mechanisms involved in the regulation of the spontaneous electrical activity and the resultant phasic contractions could conceivably lead to the identification of better targets and the development of more specific therapeutic agents to treat prostate conditions. To investigate the effect of imatinib mesylate, a tyrosine kinase receptor inhibitor, in the generation of spontaneous electrical and contractile activity in the young and ageing guinea-pig prostate. Standard tension and intracellular recording were used to measure spontaneous contractions and slow waves, respectively from the guinea-pig prostate at varying concentrations of imatinib mesylate (1-50 μm). Imatinib mesylate (1-10 μm), did not significantly affect slow waves recorded in the prostate of both age groups but at 50 μm, the amplitude of slow waves from the ageing guinea-pig prostate was significantly reduced (P < 0.05, n = 5). In contrast, the amplitude of contractions across all concentrations in the young guinea-pig prostate was reduced to between 35% and 41% of control, while the frequency was reduced to 15.7% at 1 μm (n = 7), 49.8% at 5 μm (n = 10), 46.2% at 10 μm (n = 7) and 53.1% at 50 μm (n = 5). Similarly, imatinib mesylate attenuated the amplitude and slowed the frequency of contractions in ageing guinea-pigs to 5.15% and 3.3% at 1 μm (n = 6); 21.1% and 20.8% at 5 μm (n = 8); 58.4% and 8.8% at 10 μm (n = 11); 72.7% and 60% at 50 μm (n = 5). A significant reduction in contractions but persistence of slow waves suggests imatinib mesylate may affect the smooth muscle contractile mechanism. Imatinib mesylate also significantly reduced contractions in the prostates of younger guinea pigs more than older ones, which is consistent with the notion that the younger guinea-pig prostate is more reliant on the tyrosine-dependent pacemaker ability of interstitial cells of Cajal-like prostatic interstitial cells. © 2013 The Authors BJU International © 2013 BJU International.

Anderson localisation and optical-event horizons in rogue-soliton generation.

PubMed

Saleh, Mohammed F; Conti, Claudio; Biancalana, Fabio

2017-03-06

We unveil the relation between the linear Anderson localisation process and nonlinear modulation instability. Anderson localised modes are formed in certain temporal intervals due to the random background noise. Such localised modes seed the formation of solitary waves that will appear during the modulation instability process at those preferred intervals. Afterwards, optical-event horizon effects between dispersive waves and solitons produce an artificial collective acceleration that favours the collision of solitons, which could eventually lead to a rogue-soliton generation.

ICP-AES Data Validation

EPA Pesticide Factsheets

Document designed to offer data reviewers guidance in determining the validity ofanalytical data generated through the USEPA Contract Laboratory Program (CLP) Statement ofWork (SOW) ISM01.X Inorganic Superfund Methods (Multi-Media, Multi-Concentration)

Early Warnings for Local Labor Markets

ERIC Educational Resources Information Center

Matland, Marc A.

1976-01-01

This articles summarizes the National Planning Association's (NPA) experience in its initial efforts to develop an early warning system to anticipate job openings generated in local communities by large Federal procurement contracts. (WL)

WasteWise Resource Management: Innovative Solid Waste Contracting Methods

EPA Pesticide Factsheets

Resource management is an innovative contractual partnership between a waste-generating organization and a qualified contractor that changes the nature of current disposal services to support waste minimization and recycling.

Trace Volatile Data Validation

EPA Pesticide Factsheets

Document designed to offer data reviewers guidance in determining the validity ofanalytical data generated through the USEPA Contract Laboratory Program (CLP) Statement ofWork (SOW) ISM01.X Inorganic Superfund Methods (Multi-Media, Multi-Concentration)

Matrigel Mattress: A Method for the Generation of Single Contracting Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

PubMed

Feaster, Tromondae K; Cadar, Adrian G; Wang, Lili; Williams, Charles H; Chun, Young Wook; Hempel, Jonathan E; Bloodworth, Nathaniel; Merryman, W David; Lim, Chee Chew; Wu, Joseph C; Knollmann, Björn C; Hong, Charles C

2015-12-04

The lack of measurable single-cell contractility of human-induced pluripotent stem cell-derived cardiac myocytes (hiPSC-CMs) currently limits the utility of hiPSC-CMs for evaluating contractile performance for both basic research and drug discovery. To develop a culture method that rapidly generates contracting single hiPSC-CMs and allows quantification of cell shortening with standard equipment used for studying adult CMs. Single hiPSC-CMs were cultured for 5 to 7 days on a 0.4- to 0.8-mm thick mattress of undiluted Matrigel (mattress hiPSC-CMs) and compared with hiPSC-CMs maintained on a control substrate (<0.1-mm thick 1:60 diluted Matrigel, control hiPSC-CMs). Compared with control hiPSC-CMs, mattress hiPSC-CMs had more rod-shape morphology and significantly increased sarcomere length. Contractile parameters of mattress hiPSC-CMs measured with video-based edge detection were comparable with those of freshly isolated adult rabbit ventricular CMs. Morphological and contractile properties of mattress hiPSC-CMs were consistent across cryopreserved hiPSC-CMs generated independently at another institution. Unlike control hiPSC-CMs, mattress hiPSC-CMs display robust contractile responses to positive inotropic agents, such as myofilament calcium sensitizers. Mattress hiPSC-CMs exhibit molecular changes that include increased expression of the maturation marker cardiac troponin I and significantly increased action potential upstroke velocity because of a 2-fold increase in sodium current (INa). The Matrigel mattress method enables the rapid generation of robustly contracting hiPSC-CMs and enhances maturation. This new method allows quantification of contractile performance at the single-cell level, which should be valuable to disease modeling, drug discovery, and preclinical cardiotoxicity testing. © 2015 American Heart Association, Inc.

Regulation of muscle contraction by Drebrin-like protein 1 probed by atomic force microscopy

NASA Astrophysics Data System (ADS)

Garces, Renata; Butkevich, Eugenia; Platen, Mitja; Schmidt, Christoph F.; Biophysics Team

Sarcomeres are the fundamental contractile units of striated muscle cells. They are composed of a variety of structural and regulatory proteins functioning in a precisely orchestrated fashion to enable coordinated force generation in striated muscles. Recently, we have identified a C. elegans drebrin-like protein 1 (DBN-1) as a novel sarcomere component, which stabilizes actin filaments during muscle contraction. To further characterize the function of DBN-1 in muscle cells, we generated a new dbn-1 loss-of-function allele. Absence of DBN-1 resulted in a unique worm movement phenotype, characterized by hyper-bending. It is not clear yet if DBN-1 acts to enhance or reduce the capacity for contraction. We present here an experimental mechanical study on C. elegans muscle mechanics. We measured the stiffness of the worm by indenting living C. eleganswith a micron-sized sphere adhered to the cantilever of an atomic force microscope (AFM). Modeling the worm as a pressurized elastic shell allows us to monitor the axial tension in the muscle through the measured stiffness. We compared responses of wild-type and mutant C. elegans in which DBN-1 is not expressed..

Motor unit recruitment strategies and muscle properties determine the influence of synaptic noise on force steadiness

PubMed Central

Dideriksen, Jakob L.; Negro, Francesco; Enoka, Roger M.

2012-01-01

Motoneurons receive synaptic inputs from tens of thousands of connections that cause membrane potential to fluctuate continuously (synaptic noise), which introduces variability in discharge times of action potentials. We hypothesized that the influence of synaptic noise on force steadiness during voluntary contractions is limited to low muscle forces. The hypothesis was examined with an analytical description of transduction of motor unit spike trains into muscle force, a computational model of motor unit recruitment and rate coding, and experimental analysis of interspike interval variability during steady contractions with the abductor digiti minimi muscle. Simulations varied contraction force, level of synaptic noise, size of motor unit population, recruitment range, twitch contraction times, and level of motor unit short-term synchronization. Consistent with the analytical derivations, simulations and experimental data showed that force variability at target forces above a threshold was primarily due to low-frequency oscillations in neural drive, whereas the influence of synaptic noise was almost completely attenuated by two low-pass filters, one related to convolution of motoneuron spike trains with motor unit twitches (temporal summation) and the other attributable to summation of single motor unit forces (spatial summation). The threshold force above which synaptic noise ceased to influence force steadiness depended on recruitment range, size of motor unit population, and muscle contractile properties. This threshold was low (<10% of maximal force) for typical values of these parameters. Results indicate that motor unit recruitment and muscle properties of a typical muscle are tuned to limit the influence of synaptic noise on force steadiness to low forces and that the inability to produce a constant force during stronger contractions is mainly attributable to the common low-frequency oscillations in motoneuron discharge rates. PMID:22423000

Effect of pain on the modulation in discharge rate of sternocleidomastoid motor units with force direction.

PubMed

Falla, Deborah; Lindstrøm, Rene; Rechter, Lotte; Farina, Dario

2010-05-01

To compare the behavior of sternocleidomastoid motor units of patients with chronic neck pain and healthy controls. Nine women (age, 40.4+/-3.5 yr) with chronic neck pain and nine age- and gender-matched healthy controls participated. Surface and intramuscular EMG were recorded from the sternocleidomastoid muscle bilaterally as subjects performed isometric contractions of 10-s duration in the horizontal plane at a force of 15 N in eight directions (0-360 degrees ; 45 degrees intervals) and isometric contractions at 15 and 30 N force with continuous change in force direction in the range 0-360 degrees . Motor unit behavior was monitored during the 10-s contractions and the subsequent resting periods. The mean motor unit discharge rate depended on the direction of force in the control subjects (P<0.05) but not in the patients. Moreover, in three of the nine patients, but in none of the controls, single motor unit activity continued for 8.1+/-6.1s upon completion of the contraction. The surface EMG amplitude during the circular contraction at 15N was greater for the patients (43.5+/-54.2 microV) compared to controls (16.9+/-14.9 microV; P<0.05). The modulation in discharge rate of individual motor units with force direction is reduced in the sternocleidomastoid muscle in patients with neck pain, with some patients showing prolonged motor unit activity when they were instructed to rest. These observations suggest that chronic neck pain affects the change in neural drive to muscles with force direction. Copyright 2009 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Colonic motor and vascular responses to pelvic nerve stimulation and their relation to local peptide release in the cat.

PubMed Central

Andersson, P O; Bloom, S R; Järhult, J

1983-01-01

1. The effects of stimulation of the pelvic nerves in atropinized cats at continuous, low frequencies from 1 to 16 Hz (continuous stimulation) were compared with those of stimulation at higher frequencies (10-160 Hz) delivered in 1 s bursts at 10 s intervals (stimulation in bursts), the latter simulating a commonly observed discharge pattern in vivo. Both types of stimulation evoked a transient vasodilatation. Stimulation in bursts at 20 and 40 Hz evoked more pronounced vasodilatations than continuous stimulation delivering exactly the same number of impulses over the whole period of excitation. 2. Stimulation of the pelvic nerves in bursts failed to elicit an effective contraction of the colon at any frequency tested, whereas continuous stimulation invariably evoked a contraction. 3. There was a clear-cut increase in the output of vasoactive intestinal polypeptide during both continuous and intermittent stimulation of the pelvic nerves. Stimulation in bursts caused a small but significant increase in the output of somatostatin but there was no change in the output of substance P in response to either type of pelvic nerve stimulation. 4. The colonic muscular contraction in response to continuous stimulation of the pelvic nerves was not affected by somatostatin when infused intra-arterially at the large dose of 1.0 microgram/min. 5. It is concluded that the colonic responses of atropinized cats to pelvic nerve stimulation can be substantially altered merely by changing the pattern of stimulation. Thus, whereas continuous stimulation produces both muscular contraction and vasodilatation, stimulation in bursts favours vasodilatation but is ineffective in eliciting colonic contraction. PMID:6191025

EFFECT OF LIGHT-CURING UNITS AND ACTIVATION MODE ON POLYMERIZATION SHRINKAGE AND SHRINKAGE STRESS OF COMPOSITE RESINS

PubMed Central

Lopes, Lawrence Gonzaga; Franco, Eduardo Batista; Pereira, José Carlos; Mondelli, Rafael Francisco Lia

2008-01-01

The aim of this study was to evaluate the polymerization shrinkage and shrinkage stress of composites polymerized with a LED and a quartz tungsten halogen (QTH) light sources. The LED was used in a conventional mode (CM) and the QTH was used in both conventional and pulse-delay modes (PD). The composite resins used were Z100, A110, SureFil and Bisfil 2B (chemical-cured). Composite deformation upon polymerization was measured by the strain gauge method. The shrinkage stress was measured by photoelastic analysis. The polymerization shrinkage data were analyzed statistically using two-way ANOVA and Tukey test (p≤0.05), and the stress data were analyzed by one-way ANOVA and Tukey's test (p≤0.05). Shrinkage and stress means of Bisfil 2B were statistically significant lower than those of Z100, A110 and SureFil. In general, the PD mode reduced the contraction and the stress values when compared to CM. LED generated the same stress as QTH in conventional mode. Regardless of the activation mode, SureFil produced lower contraction and stress values than the other light-cured resins. Conversely, Z100 and A110 produced the greatest contraction and stress values. As expected, the chemically cured resin generated lower shrinkage and stress than the light-cured resins. In conclusion, The PD mode effectively decreased contraction stress for Z100 and A110. Development of stress in light-cured resins depended on the shrinkage value. PMID:19089287

Neural control of muscle force: indications from a simulation model

PubMed Central

Luca, Carlo J. De

2013-01-01

We developed a model to investigate the influence of the muscle force twitch on the simulated firing behavior of motoneurons and muscle force production during voluntary isometric contractions. The input consists of an excitatory signal common to all the motor units in the pool of a muscle, consistent with the “common drive” property. Motor units respond with a hierarchically structured firing behavior wherein at any time and force, firing rates are inversely proportional to recruitment threshold, as described by the “onion skin” property. Time- and force-dependent changes in muscle force production are introduced by varying the motor unit force twitches as a function of time or by varying the number of active motor units. A force feedback adjusts the input excitation, maintaining the simulated force at a target level. The simulations replicate motor unit behavior characteristics similar to those reported in previous empirical studies of sustained contractions: 1) the initial decrease and subsequent increase of firing rates, 2) the derecruitment and recruitment of motor units throughout sustained contractions, and 3) the continual increase in the force fluctuation caused by the progressive recruitment of larger motor units. The model cautions the use of motor unit behavior at recruitment and derecruitment without consideration of changes in the muscle force generation capacity. It describes an alternative mechanism for the reserve capacity of motor units to generate extraordinary force. It supports the hypothesis that the control of motoneurons remains invariant during force-varying and sustained isometric contractions. PMID:23236008

Generation of life in a test tube: Albert Szent-Gyorgyi, Bruno Straub, and the discovery of actin.

PubMed

Rall, Jack A

2018-06-01

This is a story about a great scientist, luck, great discovery that changed the future direction of muscle research, war, a clandestine war mission, postwar politics, and an attempt to rewrite scientific history. Albert Szent-Gyorgyi, at 44 yr of age, won the Nobel Prize in 1937 for his work on vitamin C and the establishment of the groundwork of the citric acid cycle. He now wanted to investigate one of the fundamental aspects of life and settled on the study of muscle contraction. The Szent-Gyorgyi laboratory in Hungary during World War II demonstrated that contraction could be reproduced in vitro by threads consisting of just two proteins, myosin and the newly discovered protein by Bruno Straub that they called actin. Szent-Gyorgyi called seeing the contraction of these threads, which occurred in the presence of ATP and ions, "the most thrilling moment" of his scientific life. This major discovery of the generation of "life" in a test tube was totally unknown for years by the rest of the world because of the war. When the discovery was finally communicated to the world, it was not immediately accepted by all as being relevant to the physiology of muscle contraction. Nonetheless, this discovery opened up the modern phase of muscle research. Serendipity played an important role in the great discovery, and much later politics would lead to a shocking controversy around the true discoverer of actin.

Large-Scale Paraphrasing for Natural Language Understanding

DTIC Science & Technology

2018-04-01

to manufacture , use, or sell any patented invention that may relate to them. This report is the result of contracted fundamental research deemed...station contaminated local fish populations Atomic power generation in Springfield polluted indigenous seafood stocks Radioactive power generation...from PPDB. Springfield’s nuclear power plant contaminated local fish populations nuclear power station nuclear plant power plant fish stocks

Application of long-term cultured interferon-gamma enzyme-linked immunospot assay for assessing effector and memory T cell responses in cattle

USDA-ARS?s Scientific Manuscript database

Effector and memory T cells are generated through developmental programing of naïve cells following antigen recognition. If the infection is controlled, up to 95% of the T cells generated during the expansion phase are eliminated (i.e., contraction phase) and memory T cells remain, sometimes for a l...

Wounded cells drive rapid epidermal repair in the early Drosophila embryo

PubMed Central

Fernandez-Gonzalez, Rodrigo; Zallen, Jennifer A.

2013-01-01

Epithelial tissues are protective barriers that display a remarkable ability to repair wounds. Wound repair is often associated with an accumulation of actin and nonmuscle myosin II around the wound, forming a purse string. The role of actomyosin networks in generating mechanical force during wound repair is not well understood. Here we investigate the mechanisms of force generation during wound repair in the epidermis of early and late Drosophila embryos. We find that wound closure is faster in early embryos, where, in addition to a purse string around the wound, actomyosin networks at the medial cortex of the wounded cells contribute to rapid wound repair. Laser ablation demonstrates that both medial and purse-string actomyosin networks generate contractile force. Quantitative analysis of protein localization dynamics during wound closure indicates that the rapid contraction of medial actomyosin structures during wound repair in early embryos involves disassembly of the actomyosin network. By contrast, actomyosin purse strings in late embryos contract more slowly in a mechanism that involves network condensation. We propose that the combined action of two force-generating structures—a medial actomyosin network and an actomyosin purse string—contributes to the increased efficiency of wound repair in the early embryo. PMID:23985320

Advanced Stirling Radioisotope Generator Engineering Unit 2 (ASRG EU2) Final Assembly

NASA Technical Reports Server (NTRS)

Oriti, Salvatore M.

2015-01-01

NASA Glenn Research Center (GRC) has recently completed the assembly of a unique Stirling generator test article for laboratory experimentation. Under the Advanced Stirling Radioisotope Generator (ASRG) flight development contract, NASA GRC initiated a task to design and fabricate a flight-like generator for in-house testing. This test article was given the name ASRG Engineering Unit 2 (EU2) as it was effectively the second engineering unit to be built within the ASRG project. The intent of the test article was to duplicate Lockheed Martin's qualification unit ASRG design as much as possible to enable system-level tests not previously possible at GRC. After the cancellation of the ASRG flight development project, the decision was made to continue the EU2 build, and make use of a portion of the hardware from the flight development project. GRC and Lockheed Martin engineers collaborated to develop assembly procedures, leveraging the valuable knowledge gathered by Lockheed Martin during the ASRG development contract. The ASRG EU2 was then assembled per these procedures at GRC with Lockheed Martin engineers on site. The assembly was completed in August 2014. This paper details the components that were used for the assembly, and the assembly process itself.

Estimation of voluntary elicited motor neuron discharge using a peripheral nerve collision technique at different contraction strengths.

PubMed

Scheidegger, Olivier; Kamber, Nicole; Rösler, Kai Michael

2018-05-29

To estimate non-invasively the amount, recruitment pattern and discharge frequency of spinal motor neurons (MN) at contraction strength >20% of maximal voluntary contraction (MVC) of small hand muscles. A peripheral collision technique was used and consisted of supramaximal electrical stimuli at Erb's point and at the wrist, synchronizing descending volleys of action potential during voluntary isometric contractions of the abductor digiti minimi muscle at 20-80% of MVC strength and 1-8 s of contraction duration. Responses of 13 healthy volunteers were quantified and analysed using a recently described model of MN behaviour. A linear relationship between MN discharge and force generation was noticed with R2 = 0.996, and was confirmed using the simulation results (R2 = 0.997) for contraction durations up to 8 s. For each investigated force level, discharge frequency and recruitment pattern were calculated for individual MN. Using this method, MN discharge properties during voluntary activity can be estimated non-invasively. This method provides new opportunities for the non-invasive study of MN behaviour, and could be expanded to patients with conduction failure and during fatigue. Copyright © 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Prostaglandins, oxygen tension and smooth muscle tone

PubMed Central

Eckenfels, A.; Vane, J. R.

1972-01-01

1. By using indomethacin to inhibit their intramural synthesis, we have investigated the contribution of prostaglandins to the maintenance of (a) the intrinsic tone of isolated smooth muscle preparations and (b) contractions produced by drugs or high oxygen concentration. 2. When treated with indomethacin, the rat stomach strip and chick rectum preparation slowly relaxed, whether they were bathed in Krebs solution or blood. Although their sensitivity to added prostaglandin was somewhat enhanced, they became insensitive to changes in oxygen or glucose concentration. However, another smooth muscle preparation, the rat colon, was neither relaxed by indomethacin nor contracted by high oxygen concentration. 3. These results support the hypothesis that intramural generation of prostaglandin maintains the tone of some smooth muscle preparations. 4. Contractions of the guinea-pig isolated colon were induced by histamine. These contractions were normally well maintained but in Krebs solution lacking either oxygen or glucose, only the initial spike contraction remained. In the presence of indomethacin the histamine contraction was also poorly sustained, but maintenance was restored by a low concentration of prostaglandin E2. 5. Thus, the effects on smooth muscle of oxygen or glucose lack may also be mediated by reduction in the synthesis or effects of an intramural prostaglandin. Extension of this hypothesis to intestinal and vascular smooth muscle in vivo is discussed. PMID:5072227

Mercury and Cyanide Data Validation

EPA Pesticide Factsheets

Document designed to offer data reviewers guidance in determining the validity ofanalytical data generated through the USEPA Contract Laboratory Program (CLP) Statement ofWork (SOW) ISM01.X Inorganic Superfund Methods (Multi-Media, Multi-Concentration)

Financial Impacts of Nonutility Power Purchases on Investor-Owned Electric Utilities

EIA Publications

1994-01-01

Provides an overview of the issues surrounding the financial impacts of nonutility generation contracts (since the passage of the Public Utility Regulatory Policies Act of 1978) on investor owned utilities.

Low/Medium Volatile Data Validation

EPA Pesticide Factsheets

Document designed to offer data reviewers guidance in determining the validity of analytical data generated through the US EPA Contract Laboratory Program Statement of Work ISM01.X Inorganic Superfund Methods (Multi-Media, Multi-Concentration)

Systematic review of serum steroid reference intervals developed using mass spectrometry.

PubMed

Tavita, Nevada; Greaves, Ronda F

2017-12-01

The aim of this study was to perform a systematic review of the published literature to determine the available serum/plasma steroid reference intervals generated by mass spectrometry (MS) methods across all age groups in healthy subjects and to suggest recommendations to achieve common MS based reference intervals for serum steroids. MEDLINE, EMBASE and PubMed databases were used to conduct a comprehensive search for English language, MS-based reference interval studies for serum/plasma steroids. Selection of steroids to include was based on those listed in the Royal College of Pathologists of Australasia Quality Assurance Programs, Chemical Pathology, Endocrine Program. This methodology has been registered onto the PROSPERO International prospective register of systematic reviews (ID number: CRD42015029637). After accounting for duplicates, a total of 60 manuscripts were identified through the search strategy. Following critical evaluation, a total of 16 studies were selected. Of the 16 studies, 12 reported reference intervals for testosterone, 11 for 17 hydroxy-progesterone, nine for androstenedione, six for cortisol, three for progesterone, two for dihydrotestosterone and only one for aldosterone and dehydroepiandrosterone sulphate. No studies established MS-based reference intervals for oestradiol. As far as we are aware, this report provides the first comparison of the peer reviewed literature for serum/plasma steroid reference intervals generated by MS-based methods. The reference intervals based on these published studies can be used to inform the process to develop common reference intervals, and agreed reporting units for mass spectrometry based steroid methods. Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Repeated stimulation, inter-stimulus interval and inter-electrode distance alters muscle contractile properties as measured by Tensiomyography

PubMed Central

Johnson, Mark I.; Francis, Peter

2018-01-01

Context The influence of methodological parameters on the measurement of muscle contractile properties using Tensiomyography (TMG) has not been published. Objective To investigate the; (1) reliability of stimulus amplitude needed to elicit maximum muscle displacement (Dm), (2) effect of changing inter-stimulus interval on Dm (using a fixed stimulus amplitude) and contraction time (Tc), (3) the effect of changing inter-electrode distance on Dm and Tc. Design Within subject, repeated measures. Participants 10 participants for each objective. Main outcome measures Dm and Tc of the rectus femoris, measured using TMG. Results The coefficient of variance (CV) and the intra-class correlation (ICC) of stimulus amplitude needed to elicit maximum Dm was 5.7% and 0.92 respectively. Dm was higher when using an inter-electrode distance of 7cm compared to 5cm [P = 0.03] and when using an inter-stimulus interval of 10s compared to 30s [P = 0.017]. Further analysis of inter-stimulus interval data, found that during 10 repeated stimuli Tc became faster after the 5th measure when compared to the second measure [P<0.05]. The 30s inter-stimulus interval produced the most stable Tc over 10 measures compared to 10s and 5s respectively. Conclusion Our data suggest that the stimulus amplitude producing maximum Dm of the rectus femoris is reliable. Inter-electrode distance and inter-stimulus interval can significantly influence Dm and/ or Tc. Our results support the use of a 30s inter-stimulus interval over 10s or 5s. Future studies should determine the influence of methodological parameters on muscle contractile properties in a range of muscles. PMID:29451885

The anamorphic universe

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

Ijjas, Anna; Steinhardt, Paul J., E-mail: aijjas@princeton.edu, E-mail: steinh@princeton.edu

We introduce ''anamorphic'' cosmology, an approach for explaining the smoothness and flatness of the universe on large scales and the generation of a nearly scale-invariant spectrum of adiabatic density perturbations. The defining feature is a smoothing phase that acts like a contracting universe based on some Weyl frame-invariant criteria and an expanding universe based on other frame-invariant criteria. An advantage of the contracting aspects is that it is possible to avoid the multiverse and measure problems that arise in inflationary models. Unlike ekpyrotic models, anamorphic models can be constructed using only a single field and can generate a nearly scale-invariantmore » spectrum of tensor perturbations. Anamorphic models also differ from pre-big bang and matter bounce models that do not explain the smoothness. We present some examples of cosmological models that incorporate an anamorphic smoothing phase.« less

Capillary muscle

PubMed Central

Cohen, Caroline; Mouterde, Timothée; Quéré, David; Clanet, Christophe

2015-01-01

The contraction of a muscle generates a force that decreases when increasing the contraction velocity. This “hyperbolic” force–velocity relationship has been known since the seminal work of A. V. Hill in 1938 [Hill AV (1938) Proc R Soc Lond B Biol Sci 126(843):136–195]. Hill’s heuristic equation is still used, and the sliding-filament theory for the sarcomere [Huxley H, Hanson J (1954) Nature 173(4412):973–976; Huxley AF, Niedergerke R (1954) Nature 173(4412):971–973] suggested how its different parameters can be related to the molecular origin of the force generator [Huxley AF (1957) Prog Biophys Biophys Chem 7:255–318; Deshcherevskiĭ VI (1968) Biofizika 13(5):928–935]. Here, we develop a capillary analog of the sarcomere obeying Hill’s equation and discuss its analogy with muscles. PMID:25944938

Electrically, chemically, and photonically powered torsional and tensile actuation of hybrid carbon nanotube yarn muscles.

PubMed

Lima, Márcio D; Li, Na; Jung de Andrade, Mônica; Fang, Shaoli; Oh, Jiyoung; Spinks, Geoffrey M; Kozlov, Mikhail E; Haines, Carter S; Suh, Dongseok; Foroughi, Javad; Kim, Seon Jeong; Chen, Yongsheng; Ware, Taylor; Shin, Min Kyoon; Machado, Leonardo D; Fonseca, Alexandre F; Madden, John D W; Voit, Walter E; Galvão, Douglas S; Baughman, Ray H

2012-11-16

Artificial muscles are of practical interest, but few types have been commercially exploited. Typical problems include slow response, low strain and force generation, short cycle life, use of electrolytes, and low energy efficiency. We have designed guest-filled, twist-spun carbon nanotube yarns as electrolyte-free muscles that provide fast, high-force, large-stroke torsional and tensile actuation. More than a million torsional and tensile actuation cycles are demonstrated, wherein a muscle spins a rotor at an average 11,500 revolutions/minute or delivers 3% tensile contraction at 1200 cycles/minute. Electrical, chemical, or photonic excitation of hybrid yarns changes guest dimensions and generates torsional rotation and contraction of the yarn host. Demonstrations include torsional motors, contractile muscles, and sensors that capture the energy of the sensing process to mechanically actuate.

Electrically, Chemically, and Photonically Powered Torsional and Tensile Actuation of Hybrid Carbon Nanotube Yarn Muscles

NASA Astrophysics Data System (ADS)

Lima, Márcio D.; Li, Na; Jung de Andrade, Mônica; Fang, Shaoli; Oh, Jiyoung; Spinks, Geoffrey M.; Kozlov, Mikhail E.; Haines, Carter S.; Suh, Dongseok; Foroughi, Javad; Kim, Seon Jeong; Chen, Yongsheng; Ware, Taylor; Shin, Min Kyoon; Machado, Leonardo D.; Fonseca, Alexandre F.; Madden, John D. W.; Voit, Walter E.; Galvão, Douglas S.; Baughman, Ray H.

2012-11-01

Artificial muscles are of practical interest, but few types have been commercially exploited. Typical problems include slow response, low strain and force generation, short cycle life, use of electrolytes, and low energy efficiency. We have designed guest-filled, twist-spun carbon nanotube yarns as electrolyte-free muscles that provide fast, high-force, large-stroke torsional and tensile actuation. More than a million torsional and tensile actuation cycles are demonstrated, wherein a muscle spins a rotor at an average 11,500 revolutions/minute or delivers 3% tensile contraction at 1200 cycles/minute. Electrical, chemical, or photonic excitation of hybrid yarns changes guest dimensions and generates torsional rotation and contraction of the yarn host. Demonstrations include torsional motors, contractile muscles, and sensors that capture the energy of the sensing process to mechanically actuate.

Subthalamic Nucleus Local Field Potential Activity Helps Encode Motor Effort Rather Than Force in Parkinsonism

PubMed Central

Pogosyan, Alek; Ashkan, Keyoumars; Cheeran, Binith; FitzGerald, James J.; Green, Alexander L.; Aziz, Tipu; Foltynie, Thomas; Limousin, Patricia; Zrinzo, Ludvic; Brown, Peter

2015-01-01

Local field potential (LFP) recordings from patients with deep brain stimulation electrodes in the basal ganglia have suggested that frequency-specific activities correlate with force or effort, but previous studies have not been able to disambiguate the two. Here, we dissociated effort from actual force generated by contrasting the force generation of different fingers while recording LFP activity from the subthalamic nucleus (STN) in patients with Parkinson's disease who had undergone functional surgery. Patients were studied while on their normal dopaminergic medication. We investigated the relationship between frequency-specific oscillatory activity in the STN and voluntary flexion of either the index or little finger at different effort levels. At each tested effort level (10%, 25%, and 40% of the maximal voluntary contraction force of each individual finger), the index finger generated larger force than the little finger. Movement-related suppression of beta-band power in the STN LFP was significantly modulated by effort, but not by which finger was used, suggesting that the beta suppression in the STN LFP during sustained contraction serves as a proxy for effort. The absolute force scaled with beta power suppression, but with the scaling determined by the maximal voluntary contraction force of the motor effector. Our results argue against the hypothesis that the basal ganglia are directly involved in the parameterization of force during movement and support a role of the STN in the control of motor effort to be attributed to a response. PMID:25878267

Differential sensitivities of pulmonary and coronary arteries to hemoglobin-based oxygen carriers and nitrovasodilators: study in a bovine ex vivo model of vascular strips.

PubMed

Fonseca, Vera; Avizinis, Jessica; Moon-Massat, Paula; Freilich, Daniel; Kim, Hae Won; Hai, Chi-Ming

2010-01-01

Vasoconstriction is a major adverse effect of first and second generation hemoglobin-based oxygen carriers (HBOCs) that hinders their development as blood substitute. However, intravenous infusion of HBOC-201 (second generation) to patients induces significant pulmonary hypertension without significant coronary vasoconstriction. We compared contractile responses of isolated bovine pulmonary and coronary arterial strips to HBOC-201 and HBOC-205LL.LT.MW600 (third generation), polymerized bovine hemoglobins of different molecular weight, and their attenuation by nitroglycerin, sodium nitroprusside (SNP), and sodium nitrite. Pulmonary arteries developed negligible basal tone, but exhibited HBOC-dependent amplification of phenylephrine-induced contractions. In contrast, coronary arteries developed significant basal tone, and exhibited HBOC-dependent constant force increment to serotonin-induced contractions. Therefore, relative to basal tone, HBOC-induced contractions were greater in pulmonary than coronary arteries. Furthermore, HBOC-205LL.LT.MW600 appeared to be less vasoactive than HBOC-201. Unexpectedly, pulmonary and coronary arteries exhibited differential sensitivities to nitrovasodilators in parallel with their differential sensitivities to HBOC. However, SNP and sodium nitrite induced significant methemoglobin formation from HBOC, whereas nitroglycerin did not. These results suggest that phenotypic differences between pulmonary and coronary vascular smooth muscle cells could explain the differential hypertensive effects of HBOC on pulmonary and coronary circulation in patients. Among the three nitrovasodilators investigated, nitroglycerin appears to be the most promising candidate for attenuating HBOC-induced pulmonary hypertension in older HBOCs.

Contraction velocity influence the magnitude and etiology of neuromuscular fatigue during repeated maximal contractions.

PubMed

Morel, B; Clémençon, M; Rota, S; Millet, G Y; Bishop, D J; Brosseau, O; Rouffet, D M; Hautier, C A

2015-10-01

This study aimed to compare the magnitude and etiology of neuromuscular fatigue during maximal repeated contractions performed in two contraction modes (concentric vs isometric) and at two contraction velocities (30/s vs 240°/s). Eleven lower limb-trained males performed 20 sets of maximal contractions at three different angular velocities: 0°/s (KE0), 30/s (KE30), and 240°/s (KE240). Cumulated work, number of contraction, duty cycle, and contraction time were controlled. Torque, superimposed and resting twitches, as well as gas exchange, were analyzed. Increasing contraction velocity was associated with greater maximal voluntary torque loss (KE0: -9.8 ± 3.9%; KE30: -16.4 ± 8.5%; KE240: -32.6 ± 6.3%; P < 0.05). Interestingly, the torque decrease was similar for a given cumulated work. Compared with KE0, KE240 generated a greater evoked torque loss (Db100: -24.3 ± 5.3% vs -5.9 ± 6.9%; P < 0.001), a higher O2 consumption (23.7 ± 6.4 mL/min/kg vs 15.7 ± 3.8 mL/min/kg; P < 0.001), but a lower voluntary activation (VA) loss (-4.3 ± 1.6% vs -11.2 ± 4.9%; P < 0.001). The neuromuscular perturbations were intermediate for KE30 (Db100: -10.0 ± 6.8%; VA: -7.2 ± 2.8%). Although the amount of mechanical work cumulated strongly determined the magnitude of torque decrease, the contraction velocity and mode influenced the origin of the neuromuscular fatigue. The metabolic stress and peripheral fatigue increased but reduction of VA is attenuated when the contraction velocity increased from 0°/s to 240°/s. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Optimizing the Operation of Windfarms, Energy Storage and Flexible Loads in Modern Power Systems and Deregulated Electricity Markets

NASA Astrophysics Data System (ADS)

Dar, Zamiyad

The amount of wind energy in power systems is increasing at a significant rate. With this increased penetration, there are certain problems associated with the operation of windfarms which need careful attention. In the operations side, the wake effects of upstream wind turbines on downstream wind turbines can cause a reduction in the total generated power of a windfarm. On the market side, the fluctuation of real-time prices can make the operation of windfarms less profitable. Similarly, the intermittent nature of wind power prevents the windfarms from participating in the day-ahead and forward markets. On the system side, the volatile nature of wind speeds is also an obstacle for windfarms to provide frequency regulation to the system. In this thesis, we address these issues and optimize the operation of windfarms in power systems and deregulated electricity markets. First, the total power generation in a windfarm is maximized by using yaw angle of wind turbines as a control variable. We extend the existing wake models to include the effects of yaw misalignment and wake deflection of wind turbines. A numerical study is performed to find the optimal values of induction factor and yaw misalignment angle of wind turbines in a single row of a windfarm for achieving the maximum total power with wake effects. The numerical study shows that the maximum power is achieved by keeping the induction factor close to 1/3 and only changing the yaw angle to deflect the wake. We then propose a Dynamic Programming Framework (DPF) to maximize the total power production of a windfarm using yaw angle as the control variable. We compare the windfarm efficiency achieved with our DPF with the efficiency values obtained through greedy control strategy and induction factor optimization. We also extend our expressions to a windfarm with multiple rows and columns of turbines and perform simulations on the 3x3 and 4x4 grid topologies. Our results show that the optimal induction factor for most turbines is quite close to 1/3 and yaw angle acts as the dominant optimization variable. In the next part of this dissertation, a system comprising of a windfarm and energy storage operating in real-time electricity markets is studied. An Energy-balancing Threshold Price (ETP) policy is proposed to maximize the revenue of a windfarm with on-site storage. We propose and analyze a scheme for a windfarm to store or sell energy based on a threshold price. The threshold price is calculated based on long-term distributions of the electricity price and wind power generation processes, and is chosen so as to balance the energy flows in and out of the storage-equipped windfarm. It is also shown mathematically that the proposed policy is optimal in terms of the long-term revenue generated. Comparing it with the optimal policy that has knowledge of the future, we observe that the revenue obtained by the proposed ETP policy is approximately 90% of the maximum attainable revenue at a storage capacity of 10-15 times the power rating of the windfarm. The intermittent nature of wind power is a hindrance to the efficient participation of windfarms in the day-ahead and forward electricity markets. In this regard, a flexible forward contract is proposed in this dissertation which allows the windfarms to enter into a forward contract with flexible load with an option to deviate from the contracted amount of power. Using such a flexible contract would allow the windfarms to supply more or less than the contracted amount of power in case of unexpected wind conditions or real-time prices. We also propose models for forecasting wind power and real-time electricity prices. The comparison between the proposed contracting framework and a simple fixed contract (currently existing in the market) for different levels of flexibility and load shows that there is a net gain in windfarm revenues, if the transaction price of the two contracts are set equal. Lastly, we present and analyze distributed control schemes for frequency regulation in a smart grid using energy storage, wind generators, demand response and conventional generators while having no communication or data sharing between them. We also propose a novel control scheme for frequency support by energy storage in which the power output of energy storage changes proportionally with the reduction in its available energy. The application of the proposed control schemes indicates an improvement in system frequency characteristics, when there is a sudden net loss of generation.

Matrix metalloproteinase-9 activates TGF-β and stimulates fibroblast contraction of collagen gels.

PubMed

Kobayashi, Tetsu; Kim, HuiJung; Liu, Xiangde; Sugiura, Hisatoshi; Kohyama, Tadashi; Fang, Qiuhong; Wen, Fu-Qiang; Abe, Shinji; Wang, Xingqi; Atkinson, Jeffrey J; Shipley, James M; Senior, Robert M; Rennard, Stephen I

2014-06-01

Matrix metalloproteinase-9 (MMP-9) is a matrix-degrading enzyme implicated in many biological processes, including inflammation. It is produced by many cells, including fibroblasts. When cultured in three-dimensional (3D) collagen gels, fibroblasts contract the surrounding matrix, a function that is thought to model the contraction that characterizes both normal wound repair and fibrosis. The current study was designed to evaluate the role of endogenously produced MMP-9 in fibroblast contraction of 3D collagen gels. Fibroblasts from mice lacking expression of MMP-9 and human lung fibroblasts (HFL-1) transfected with MMP-9 small-interfering RNA (siRNA) were used. Fibroblasts were cast into type I collagen gels and floated in culture medium with or without transforming growth factor (TGF)-β1 for 5 days. Gel size was determined daily using an image analysis system. Gels made from MMP-9 siRNA-treated human fibroblasts contracted less than control fibroblasts, as did fibroblasts incubated with a nonspecific MMP inhibitor. Similarly, fibroblasts cultured from MMP-9-deficient mice contracted gels less than did fibroblasts from control mice. Transfection of the MMP-9-deficient murine fibroblasts with a vector expressing murine MMP-9 restored contractile activity to MMP-9-deficient fibroblasts. Inhibition of MMP-9 reduced active TGF-β1 and reduced several TGF-β1-driven responses, including activity of a Smad3 reporter gene and production of fibronectin. Because TGF-β1 also drives fibroblast gel contraction, this suggests the mechanism for MMP-9 regulation of contraction is through the generation of active TGF-β1. This study provides direct evidence that endogenously produced MMP-9 has a role in regulation of tissue contraction of 3D collagen gels mediated by fibroblasts. Copyright © 2014 the American Physiological Society.

High-definition spatiotemporal mapping of contractile activity in the isolated proximal colon of the rabbit.

PubMed

Lentle, Roger G; Janssen, Patrick W M; Asvarujanon, Patchana; Chambers, Paul; Stafford, Kevin J; Hemar, Yacine

2008-03-01

Four types of contractile activity were identified and characterised in the isolated triple haustrated proximal colon of the rabbit using high-definition spatiotemporal mapping techniques. Mass peristalses were hexamethonium-sensitive deep circular contractions with associated taenial longitudinal contractile activity that occurred irregularly and propagated rapidly aborad, preceded by a zone of local lumen distension. They were sufficiently sustained for each event to occupy the length of the isolated colonic segment and the contraction persisted longer orally than aborally, the difference being more pronounced when lumen contents were viscous. Haustra were bounded by deep even-spaced ring contractions that progressed slowly aborad (haustral progression). Haustral formation and progression were hexamethonium-sensitive and coordinated across intertaenial domains. Ripples were hexamethonium-resistant phasic circular contractions that propagated predominantly orad at varying rates. In the presence of haustra, they were uncoordinated across intertaenial domains but were more coordinated when haustra were absent. Fast phasic contractions were relatively shallow hexamethonium-resistant contractions that propagated rapidly in a predominantly aborad direction. Fast phasic circular contractions were accompanied by taenial longitudinal muscle contractions which increased in amplitude prior to a mass peristaltic event and following the administration of hexamethonium. On the basis of the concurrence and interaction of these contractile activities, we hypothesise that dual pacemakers are present with fast phasic contractions being modulated by the interstitial cells of Cajal in the Auerbach's plexus (ICC-MY) while ripples are due to the submucosal ICC (ICC-SM). Further, that ICC-SM mediate the enteric motor neurons that generate haustral progression, while the intramuscular ICC (ICC-IM) mediate mass peristalsis. The orad movement of watery fluid was possibly due to ripples in the absence of haustra.

Age-related differences in muscle fatigue vary by contraction type: a meta-analysis.

PubMed

Avin, Keith G; Law, Laura A Frey

2011-08-01

During senescence, despite the loss of strength (force-generating capability) associated with sarcopenia, muscle endurance may improve for isometric contractions. The purpose of this study was to perform a systematic meta-analysis of young versus older adults, considering likely moderators (ie, contraction type, joint, sex, activity level, and task intensity). A 2-stage systematic review identified potential studies from PubMed, CINAHL, PEDro, EBSCOhost: ERIC, EBSCOhost: Sportdiscus, and The Cochrane Library. Studies reporting fatigue tasks (voluntary activation) performed at a relative intensity in both young (18-45 years of age) and old (≥ 55 years of age) adults who were healthy were considered. Sample size, mean and variance outcome data (ie, fatigue index or endurance time), joint, contraction type, task intensity (percentage of maximum), sex, and activity levels were extracted. Effect sizes were (1) computed for all data points; (2) subgrouped by contraction type, sex, joint or muscle group, intensity, or activity level; and (3) further subgrouped between contraction type and the remaining moderators. Out of 3,457 potential studies, 46 publications (with 78 distinct effect size data points) met all inclusion criteria. A lack of available data limited subgroup analyses (ie, sex, intensity, joint), as did a disproportionate spread of data (most intensities ≥ 50% of maximum voluntary contraction). Overall, older adults were able to sustain relative-intensity tasks significantly longer or with less force decay than younger adults (effect size=0.49). However, this age-related difference was present only for sustained and intermittent isometric contractions, whereas this age-related advantage was lost for dynamic tasks. When controlling for contraction type, the additional modifiers played minor roles. Identifying muscle endurance capabilities in the older adult may provide an avenue to improve functional capabilities, despite a clearly established decrement in peak torque.

Polymerization contraction stress in light-cured compomer restorative materials.

PubMed

Chen, H Y; Manhart, J; Kunzelmann, K-H; Hickel, R

2003-11-01

The magnitude and kinetics of polymerization contraction stress build-up may be potential predictors of bond failure of adhesive restorations. The present study determined these properties of seven commercial compomers (Dyract, Dyract AP, F2000 Rasant, Hytac, Compoglass F, Luxat, Glasiosite). Polymerization shrinkage was generated by 40 s light curing the test materials (800 mW/cm2). The contraction force induced was recorded for 300 s at room temperature (23-24 degrees C) by means of a Stress-Strain-Analyzer (C factor=0.33). Maximum contraction stress (MPa), coefficient of near linear fit of contraction force/time (gradient) and relative force rate (%/s) of each material were compared with that of two hybrid composites (Tetric Ceram, Prodigy). The statistical analysis was conducted by ANOVA (alpha=0.05) and post hoc Tukey's test. No statistically significant differences in the maximum stress between Glasiosite (2.27+/-0.06 MPa), Hytac (2.31+/-0.07 MPa) and Tetric Ceram (2.21+/-0.11 MPa), and between Compoglass F (2.60+/-0.18 MPa) and Prodigy (2.70+/-0.06 MPa) were found. The contraction stress of F2000 Rasant (3.41+/-0.09 MPa) and Luxat (3.33+/-0.08 MPa) were significantly highest, whilst Dyract exhibited the significantly lowest shrinkage stress (1.27+/-0.08 MPa) among the tested materials. High contraction stress, early start of stress build-up and rapid contraction force development may lead to failure of bond to tooth structure. This study suggested that the contraction stress and kinetic behavior of compomers are generally similar to those of hybrid composites in a dry condition. Dyract might be superior in maintaining the bond with cavity walls compared to conventional hybrid composites in view of its low shrinkage stress.

Multiple ECG Fiducial Points-Based Random Binary Sequence Generation for Securing Wireless Body Area Networks.

PubMed

Zheng, Guanglou; Fang, Gengfa; Shankaran, Rajan; Orgun, Mehmet A; Zhou, Jie; Qiao, Li; Saleem, Kashif

2017-05-01

Generating random binary sequences (BSes) is a fundamental requirement in cryptography. A BS is a sequence of N bits, and each bit has a value of 0 or 1. For securing sensors within wireless body area networks (WBANs), electrocardiogram (ECG)-based BS generation methods have been widely investigated in which interpulse intervals (IPIs) from each heartbeat cycle are processed to produce BSes. Using these IPI-based methods to generate a 128-bit BS in real time normally takes around half a minute. In order to improve the time efficiency of such methods, this paper presents an ECG multiple fiducial-points based binary sequence generation (MFBSG) algorithm. The technique of discrete wavelet transforms is employed to detect arrival time of these fiducial points, such as P, Q, R, S, and T peaks. Time intervals between them, including RR, RQ, RS, RP, and RT intervals, are then calculated based on this arrival time, and are used as ECG features to generate random BSes with low latency. According to our analysis on real ECG data, these ECG feature values exhibit the property of randomness and, thus, can be utilized to generate random BSes. Compared with the schemes that solely rely on IPIs to generate BSes, this MFBSG algorithm uses five feature values from one heart beat cycle, and can be up to five times faster than the solely IPI-based methods. So, it achieves a design goal of low latency. According to our analysis, the complexity of the algorithm is comparable to that of fast Fourier transforms. These randomly generated ECG BSes can be used as security keys for encryption or authentication in a WBAN system.

By-pass filters : taking your fleet the extra mile

DOT National Transportation Integrated Search

2000-01-01

There has been an industry-wide push over the last few years to extend oil drain intervals on fleet equipment. This industry demand is an effort to reduce downtime, reduce waste oil generation, and cut maintenance costs. Extended oil drain intervals ...

ANO1 in intramuscular interstitial cells of Cajal plays a key role in the generation of slow waves and tone in the internal anal sphincter

PubMed Central

Hannah, E. E.; Zhu, M. H.; Lyle, H. E.; Rock, J. R.; Sanders, K. M.; Ward, S. M.; Keef, K. D.

2017-01-01

Key points The internal anal sphincter develops tone important for maintaining high anal pressure and continence. Controversy exists regarding the mechanisms underlying tone development.We examined the hypothesis that tone depends upon electrical slow waves (SWs) initiated in intramuscular interstitial cells of Cajal (ICC‐IM) by activation of Ca2+‐activated Cl− channels (ANO1, encoded by Ano1) and voltage‐dependent L‐type Ca2+ channels (CavL, encoded by Cacna1c).Measurement of membrane potential and contraction indicated that ANO1 and CavL have a central role in SW generation, phasic contractions and tone, independent of stretch.ANO1 expression was examined in wildtype and Ano1/+egfp mice with immunohistochemical techniques. Ano1 and Cacna1c expression levels were examined by quantitative PCR in fluorescence‐activated cell sorting.ICC‐IM were the predominant cell type expressing ANO1 and the most likely candidate for SW generation. SWs in ICC‐IM are proposed to conduct to smooth muscle where Ca2+ entry via CavL results in phasic activity that sums to produce tone. Abstract The mechanism underlying tone generation in the internal anal sphincter (IAS) is controversial. We examined the hypothesis that tone depends upon generation of electrical slow waves (SWs) initiated in intramuscular interstitial cells of Cajal (ICC‐IM) by activation of Ca2+‐activated Cl− channels (encoded by Ano1) and voltage‐dependent L‐type Ca2+ channels (encoded by Cacna1c). Phasic contractions and tone in the IAS were nearly abolished by ANO1 and CavL antagonists. ANO1 antagonists also abolished SWs as well as transient depolarizations that persisted after addition of CavL antagonists. Tone development in the IAS did not require stretch of muscles, and the sensitivity of contraction to ANO1 antagonists was the same in stretched versus un‐stretched muscles. ANO1 expression was examined in wildtype and Ano1/+egfp mice with immunohistochemical techniques. Dual labelling revealed that ANO1 expression could be resolved in ICC but not smooth muscle cells (SMCs) in the IAS and rectum. Ano1, Cacna1c and Kit gene expression were the same in extracts of IAS and rectum muscles. In IAS cells isolated with fluorescence‐activated cell sorting, Ano1 expression was 26.5‐fold greater in ICC than in SMCs while Cacna1c expression was only 2‐fold greater in SMCs than in ICC. These data support a central role for ANO1 and CavL in the generation of SWs and tone in the IAS. ICC‐IM are the probable cellular candidate for ANO1 currents and SW generation. We propose that ANO1 and CavL collaborate to generate SWs in ICC‐IM followed by conduction to adjacent SMCs where phasic calcium entry through CavL sums to produce tone. PMID:28054347

RISMA: A Rule-based Interval State Machine Algorithm for Alerts Generation, Performance Analysis and Monitoring Real-Time Data Processing

NASA Astrophysics Data System (ADS)

Laban, Shaban; El-Desouky, Aly

2013-04-01

The monitoring of real-time systems is a challenging and complicated process. So, there is a continuous need to improve the monitoring process through the use of new intelligent techniques and algorithms for detecting exceptions, anomalous behaviours and generating the necessary alerts during the workflow monitoring of such systems. The interval-based or period-based theorems have been discussed, analysed, and used by many researches in Artificial Intelligence (AI), philosophy, and linguistics. As explained by Allen, there are 13 relations between any two intervals. Also, there have also been many studies of interval-based temporal reasoning and logics over the past decades. Interval-based theorems can be used for monitoring real-time interval-based data processing. However, increasing the number of processed intervals makes the implementation of such theorems a complex and time consuming process as the relationships between such intervals are increasing exponentially. To overcome the previous problem, this paper presents a Rule-based Interval State Machine Algorithm (RISMA) for processing, monitoring, and analysing the behaviour of interval-based data, received from real-time sensors. The proposed intelligent algorithm uses the Interval State Machine (ISM) approach to model any number of interval-based data into well-defined states as well as inferring them. An interval-based state transition model and methodology are presented to identify the relationships between the different states of the proposed algorithm. By using such model, the unlimited number of relationships between similar large numbers of intervals can be reduced to only 18 direct relationships using the proposed well-defined states. For testing the proposed algorithm, necessary inference rules and code have been designed and applied to the continuous data received in near real-time from the stations of International Monitoring System (IMS) by the International Data Centre (IDC) of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The CLIPS expert system shell has been used as the main rule engine for implementing the algorithm rules. Python programming language and the module "PyCLIPS" are used for building the necessary code for algorithm implementation. More than 1.7 million intervals constitute the Concise List of Frames (CLF) from 20 different seismic stations have been used for evaluating the proposed algorithm and evaluating stations behaviour and performance. The initial results showed that proposed algorithm can help in better understanding of the operation and performance of those stations. Different important information, such as alerts and some station performance parameters, can be derived from the proposed algorithm. For IMS interval-based data and at any period of time it is possible to analyze station behavior, determine the missing data, generate necessary alerts, and to measure some of station performance attributes. The details of the proposed algorithm, methodology, implementation, experimental results, advantages, and limitations of this research are presented. Finally, future directions and recommendations are discussed.

Integrin receptor involvement in actin cable formation in an in vitro model of events associated with wound contraction.

PubMed

Stephens, P; Genever, P G; Wood, E J; Raxworthy, M J

1997-01-01

Actin cables have been reported to act in vivo as contractile 'purse strings' capable of closing embryonic wounds through generation of circumferential tension. Furthermore, their involvement in wounds within in vitro model systems suggests that actin cable contraction may be an important mechanism involved in the process of wound closure. The aim of this study therefore, was to investigate the appearance of actin cables in a contracting fibroblast populated collagen lattice, an in vitro model of events associated with wound contraction. Utilising this in vitro model, the time-course of actin cable production was investigated and the involvement of integrin receptors analysed using immunofluorescent labelling techniques. Over a period of hours distinct cellular cable-like structures developed at the edges of collagen lattices coinciding with the onset of contraction. Cellular organisation within the cable was evident as was polymerisation of actin microfilaments into elongated stress fibres forming a continuous cell-cell 'actin cable' around the circumference of the lattice. Immunolocalisation demonstrated that integrin receptor subunits beta 1 and alpha 2 but not alpha 5 were involved in apparent intimate cell-cell contact between juxtaposed fibroblasts within this actin cable. This study demonstrates the involvement of integrin receptors in actin cable formation within collagen lattice systems undergoing reorganisation. Such integrin involvement may enable participating cells to respond to the tensional status of their surrounding environment and via cell-cell communication, to permit a co-ordinated contraction of the cable. It is concluded that integrin receptor involvement in active actin cable contraction may be involved in the process of wound contraction.

Tensor contraction engine: Abstraction and automated parallel implementation of configuration-interaction, coupled-cluster, and many-body perturbation theories

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

Hirata, So

2003-11-20

We develop a symbolic manipulation program and program generator (Tensor Contraction Engine or TCE) that automatically derives the working equations of a well-defined model of second-quantized many-electron theories and synthesizes efficient parallel computer programs on the basis of these equations. Provided an ansatz of a many-electron theory model, TCE performs valid contractions of creation and annihilation operators according to Wick's theorem, consolidates identical terms, and reduces the expressions into the form of multiple tensor contractions acted by permutation operators. Subsequently, it determines the binary contraction order for each multiple tensor contraction with the minimal operation and memory cost, factorizes commonmore » binary contractions (defines intermediate tensors), and identifies reusable intermediates. The resulting ordered list of binary tensor contractions, additions, and index permutations is translated into an optimized program that is combined with the NWChem and UTChem computational chemistry software packages. The programs synthesized by TCE take advantage of spin symmetry, Abelian point-group symmetry, and index permutation symmetry at every stage of calculations to minimize the number of arithmetic operations and storage requirement, adjust the peak local memory usage by index range tiling, and support parallel I/O interfaces and dynamic load balancing for parallel executions. We demonstrate the utility of TCE through automatic derivation and implementation of parallel programs for various models of configuration-interaction theory (CISD, CISDT, CISDTQ), many-body perturbation theory [MBPT(2), MBPT(3), MBPT(4)], and coupled-cluster theory (LCCD, CCD, LCCSD, CCSD, QCISD, CCSDT, and CCSDTQ).« less

The relationship between EMG activity and extensor moment generation in the erector spinae muscles during bending and lifting activities.

PubMed

Dolan, P; Adams, M A

1993-01-01

The relationship between EMG activity and extensor moment generation in the erector spinae muscles was investigated under isometric and concentric conditions. The full-wave rectified and averaged EMG signal was recorded from skin-surface electrodes located over the belly of the erector spinae at the levels of T10 and L3, and compared with measurements of extensor moment. The effects of muscle length and contraction velocity were studied by measuring the overall curvature (theta) and rate of change of curvature (d theta/dt) of the lumbar spine in the sagittal plane, using the '3-Space Isotrak' system. Isometric contractions were investigated with the subjects pulling up on a load cell attached to the floor. Hand height was varied to produce different amounts of lumbar flexion, as indicated by changes in lumbar curvature. The extensor moment was found to be linearly related to EMG activity, and the 'gradient' and 'intercept' of the relationship were themselves dependent upon the lumbar curvature at the time of testing. Concentric contractions were investigated with the subjects extending from a seated toe-touching position, at various speeds, while the torque exerted on the arm of a Cybex dynamometer was continuously measured. Under these conditions the EMG signal (E) was higher than the isometric signal (E0) associated with the same torque. E and E0 were related as follows: E0 = E/(1 + A d theta/dt), where A = 0.0014 exp (0.045P) and P = percentage lumbar flexion. This equation was used to correct the EMG data for the effect of contraction velocity. The corrected data were then used, in conjunction with the results of the isometric calibrations, to calculate the extensor moment generated by the erector spinae muscles during bending and lifting activities. The extensor moment can itself be used to calculate the compressive force acting on the lumbar spine.

Outage maintenance checks on large generator windings

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

Nindra, B.; Jeney, S.I.; Slobodinsky, Y.

In the present days of austerity, more constraints and pressures are being brought on the maintenance engineers to certify the generators for their reliability and life extension. The outages are shorter and intervals between the outages are becoming longer. The annual outages were very common when utilities had no regulatory constraints and also had standby capacities. Furthermore, due to lean and mean budgets, outage maintenance programs are being pursued more aggressively, so that longer interval outages can be achieved to ensure peak generator performance. This paper will discuss various visual checks, electrical tests and recommended fixes to achieve the abovemore » mentioned objectives, in case any deficiencies are found.« less

Method of and apparatus for generating an interstitial point in a data stream having an even number of data points

NASA Technical Reports Server (NTRS)

Edwards, T. R. (Inventor)

1985-01-01

Apparatus for doubling the data density rate of an analog to digital converter or doubling the data density storage capacity of a memory deviced is discussed. An interstitial data point midway between adjacent data points in a data stream having an even number of equal interval data points is generated by applying a set of predetermined one-dimensional convolute integer coefficients which can include a set of multiplier coefficients and a normalizer coefficient. Interpolator means apply the coefficients to the data points by weighting equally on each side of the center of the even number of equal interval data points to obtain an interstital point value at the center of the data points. A one-dimensional output data set, which is twice as dense as a one-dimensional equal interval input data set, can be generated where the output data set includes interstitial points interdigitated between adjacent data points in the input data set. The method for generating the set of interstital points is a weighted, nearest-neighbor, non-recursive, moving, smoothing averaging technique, equivalent to applying a polynomial regression calculation to the data set.

Mechanism Design for Task Procurement with Flexible Quality of Service

NASA Astrophysics Data System (ADS)

Gerding, Enrico H.; Larson, Kate; Rogers, Alex; Jennings, Nicholas R.

In this paper, we consider the problem where an agent wishes to complete a single computational task, but lacks the required resources. Instead, it must contract self-interested service providers, who are able to flexibly manipulate the quality of service they deliver, in order to maximise their own utility. We extend an existing model to allow for multiple such service providers to be contracted for the same task, and derive optimal task procurement mechanisms in the setting where the agent has full knowledge of the cost functions of these service providers (considering both simultaneous and sequential procurement). We then extend these results to the incomplete information setting where the agent must elicit cost information from the service providers, and we characterise a family of incentive-compatible and individually-rational mechanisms. We show empirically that sequential procurement always generates greater utility for the agent compared to simultaneous procurement, and that over a range of settings, contracting multiple providers is preferable to contracting just one.

Vibroacoustic processes and structural variations in muscular tissue

NASA Astrophysics Data System (ADS)

Antonets, V. A.; Klochkov, B. N.; Kovaleva, E. P.

1995-03-01

This paper reviews the problems and results obtained in the course of experimental and theoretical investigations of the vibroacoustic activity of contracting muscles. Two types of such processes are examined: (1) acoustic vibrations due to the macromolecular recombinations of muscle proteins, which are responsible for the muscle contraction, and (2) acoustic vibrations associated with the finite accuracy and speed of the receptor-effector system that controls the muscle contraction. By investigating the acoustic vibrations, we examine structural recombinations (conformation variations) in macromolecules during mechanochemical reactions. Since chemical reactions of macromolecules are always accompanied by conformational recombinations, the generation mechanism, which is responsible for the contraction processes in a muscular tissue, can also be extended to other macromolecular media. Investigation of infrasound vibrations makes it possible to explore the quality and error of control for the processes in the muscle under different types of loading. Since a living body is controlled via perceptions, the latter can be quantitatively estimated by the parametess of infrasound vibrations.

Joint DoD versus Navy Specific Lead Generation Advertising: Comparison of Conversion Rates to Quality Enlistments and Marginal Costs.

DTIC Science & Technology

1984-09-01

7D-Rt46 982 JOINT DOD VERSUS NAVY SPECIFIC LEAD GENERATION j/j ADVERTISING : COMPARISON OF..(U) J B FUGUR SCHOOL OF N BUSINESS DURHAM NC R C MOREY...REPORT I PEPIO0 COV9cO JOINT DOD VERSUS NAVY SPECIFIC LEAD GENERATION Technical Report ADVERTISING : Comparison of Conversion Rates to (0 Quality...block number) . Upper-Mental, High School Degree, enlistment contracts, national leads, Z Joint DOD advertising , Service Specific Advertising , conversion

Verification of Abbott 25-OH-vitamin D assay on the architect system.

PubMed

Hutchinson, Katrina; Healy, Martin; Crowley, Vivion; Louw, Michael; Rochev, Yury

2017-04-01

Analytical and clinical verification of both old and new generations of the Abbott total 25-hydroxyvitamin D (25OHD) assays, and an examination of reference Intervals. Determination of between-run precision, and Deming comparison between patient sample results for 25OHD on the Abbott Architect, DiaSorin Liaison and AB SCIEX API 4000 (LC-MS/MS). Establishment of uncertainty of measurement for 25OHD Architect methods using old and new generations of the reagents, and estimation of reference interval in healthy Irish population. For between-run precision the manufacturer claims 2.8% coefficients of variation (CVs) of 2.8% and 4.6% for their high and low controls, respectively. Our instrument showed CVs between 4% and 6.2% for all levels of the controls on both generations of the Abbott reagents. The between-run uncertainties were 0.28 and 0.36, with expanded uncertainties 0.87 and 0.98 for the old and the new generations of reagent, respectively. The difference between all methods used for patients' samples was within total allowable error, and the instruments produced clinically equivalent results. The results covered the medical decision points of 30, 40, 50 and 125 nmol/L. The reference interval for total 25OHD in our healthy Irish subjects was lower than recommended levels (24-111 nmol/L). In a clinical laboratory Abbott 25OHD immunoassays are a useful, rapid and accurate method for measuring total 25OHD. The new generation of the assay was confirmed to be reliable, accurate, and a good indicator for 25OHD measurement. More study is needed to establish reference intervals that correctly represent the healthy population in Ireland.

Automated Interval velocity picking for Atlantic Multi-Channel Seismic Data

NASA Astrophysics Data System (ADS)

Singh, Vishwajit

2016-04-01

This paper described the challenge in developing and testing a fully automated routine for measuring interval velocities from multi-channel seismic data. Various approaches are employed for generating an interactive algorithm picking interval velocity for continuous 1000-5000 normal moveout (NMO) corrected gather and replacing the interpreter's effort for manual picking the coherent reflections. The detailed steps and pitfalls for picking the interval velocities from seismic reflection time measurements are describe in these approaches. Key ingredients these approaches utilized for velocity analysis stage are semblance grid and starting model of interval velocity. Basin-Hopping optimization is employed for convergence of the misfit function toward local minima. SLiding-Overlapping Window (SLOW) algorithm are designed to mitigate the non-linearity and ill- possessedness of root-mean-square velocity. Synthetic data case studies addresses the performance of the velocity picker generating models perfectly fitting the semblance peaks. A similar linear relationship between average depth and reflection time for synthetic model and estimated models proposed picked interval velocities as the starting model for the full waveform inversion to project more accurate velocity structure of the subsurface. The challenges can be categorized as (1) building accurate starting model for projecting more accurate velocity structure of the subsurface, (2) improving the computational cost of algorithm by pre-calculating semblance grid to make auto picking more feasible.

Reversing the Course of Forgetting

PubMed Central

White, K. Geoffrey; Brown, Glenn S

2011-01-01

Forgetting functions were generated for pigeons in a delayed matching-to-sample task, in which accuracy decreased with increasing retention-interval duration. In baseline training with dark retention intervals, accuracy was high overall. Illumination of the experimental chamber by a houselight during the retention interval impaired performance accuracy by increasing the rate of forgetting. In novel conditions, the houselight was lit at the beginning of a retention interval and then turned off partway through the retention interval. Accuracy was low at the beginning of the retention interval and then increased later in the interval. Thus the course of forgetting was reversed. Such a dissociation of forgetting from the passage of time is consistent with an interference account in which attention or stimulus control switches between the remembering task and extraneous events. PMID:21909163

Physics of Weightlifting

NASA Astrophysics Data System (ADS)

Cohen, Caroline

2014-11-01

In the footsteps of J.B. Keller who determined the optimal strategy to run a race, we investigate weightlifting records. We measure the dynamics of lifting barbells of different masses at Bench Press for different athletes. To understand the shape of experimental results, we need both a macroscopic mechanic model and microscopic description of muscle contraction. We dive into muscle in order to understand the relation between force generated by the muscle and its contraction velocity and draw a capillary analogy of muscle contraction. Finally we use the Deshcherevskii kinetik model and derive the dynamics of the barbell. From the fit between data and predictions, we extract microscopic characteristics of muscles. We consider to apply this protocole to diagnose muscle aging or dysfunctions. C. Cohen, B. Darbois Texier, D. Quere, G. Laffaye, C. Clanet.

Insuring wind energy production

NASA Astrophysics Data System (ADS)

D'Amico, Guglielmo; Petroni, Filippo; Prattico, Flavio

2017-02-01

This paper presents an insurance contract that the supplier of wind energy may subscribe in order to immunize the production of electricity against the volatility of the wind speed process. The other party of the contract may be any dispatchable energy producer, like gas turbine or hydroelectric generator, which can supply the required energy in case of little or no wind. The adoption of a stochastic wind speed model allows the computation of the fair premium that the wind power supplier has to pay in order to hedge the risk of inadequate output of electricity at any time. Recursive type equations are obtained for the prospective mathematical reserves of the insurance contract and for their higher order moments. The model and the validity of the results are illustrated through a numerical example.

Overview 2004 of NASA-Stirling Convertor CFD Model Development and Regenerator R and D Efforts

NASA Technical Reports Server (NTRS)

Tew, Roy C.; Dyson, Rodger W.; Wilson, Scott D.; Demko, Rikako

2004-01-01

This paper reports on accomplishments in 2004 in (1) development of Stirling-convertor CFD models at NASA Glenn and via a NASA grant, (2) a Stirling regenerator-research effort being conducted via a NASA grant (a follow-on effort to an earlier DOE contract), and (3) a regenerator-microfabrication contract for development of a "next-generation Stirling regenerator." Cleveland State University is the lead organization for all three grant/contractual efforts, with the University of Minnesota and Gedeon Associates as subcontractors. Also, the Stirling Technology Company and Sunpower, Inc. are both involved in all three efforts, either as funded or unfunded participants. International Mezzo Technologies of Baton Rouge, Louisiana is the regenerator fabricator for the regenerator-microfabrication contract. Results of the efforts in these three areas are summarized.

Massive gravity and the suppression of anisotropies and gravitational waves in a matter-dominated contracting universe

NASA Astrophysics Data System (ADS)

Lin, Chunshan; Quintin, Jerome; Brandenberger, Robert H.

2018-01-01

We consider a modified gravity model with a massive graviton, but which nevertheless only propagates two gravitational degrees of freedom and which is free of ghosts. We show that non-singular bouncing cosmological background solutions can be generated. In addition, the mass term for the graviton prevents anisotropies from blowing up in the contracting phase and also suppresses the spectrum of gravitational waves compared to that of the scalar cosmological perturbations. This addresses two of the main problems of the matter bounce scenario.

The early universe history from contraction-deformation of the Standard Model

NASA Astrophysics Data System (ADS)

Gromov, N. A.

2017-03-01

The elementary particles evolution in the early Universe from Plank time up to several milliseconds is presented. The developed theory is based on the high-temperature (high-energy) limit of the Standard Model which is generated by the contractions of its gauge groups. At the infinite temperature all particles lose masses. Only massless neutral -bosons, massless Z-quarks, neutrinos and photons are survived in this limit. The weak interactions become long-range and are mediated by neutral currents, quarks have only one color degree of freedom.

Annual Progress Report FY-82. Volume I.

DTIC Science & Technology

1982-01-01

Comparison of Binaural Versus 316 Monaural Amplification. (FY-81PI) 2535 Development of Method for Generating 318 Individualized Aural Rehabilitation...Oncology Group. 428 (FY-74 I ) 4116 The Evaluation of Petal Systolic Time Intervals 429 and Beat interval Variation in Fetal heart Rate as Early

Spike-Interval Triggered Averaging Reveals a Quasi-Periodic Spiking Alternative for Stochastic Resonance in Catfish Electroreceptors

PubMed Central

Lankheet, Martin J. M.; Klink, P. Christiaan; Borghuis, Bart G.; Noest, André J.

2012-01-01

Catfish detect and identify invisible prey by sensing their ultra-weak electric fields with electroreceptors. Any neuron that deals with small-amplitude input has to overcome sensitivity limitations arising from inherent threshold non-linearities in spike-generation mechanisms. Many sensory cells solve this issue with stochastic resonance, in which a moderate amount of intrinsic noise causes irregular spontaneous spiking activity with a probability that is modulated by the input signal. Here we show that catfish electroreceptors have adopted a fundamentally different strategy. Using a reverse correlation technique in which we take spike interval durations into account, we show that the electroreceptors generate a supra-threshold bias current that results in quasi-periodically produced spikes. In this regime stimuli modulate the interval between successive spikes rather than the instantaneous probability for a spike. This alternative for stochastic resonance combines threshold-free sensitivity for weak stimuli with similar sensitivity for excitations and inhibitions based on single interspike intervals. PMID:22403709

An inventory-theory-based interval-parameter two-stage stochastic programming model for water resources management

NASA Astrophysics Data System (ADS)

Suo, M. Q.; Li, Y. P.; Huang, G. H.

2011-09-01

In this study, an inventory-theory-based interval-parameter two-stage stochastic programming (IB-ITSP) model is proposed through integrating inventory theory into an interval-parameter two-stage stochastic optimization framework. This method can not only address system uncertainties with complex presentation but also reflect transferring batch (the transferring quantity at once) and period (the corresponding cycle time) in decision making problems. A case of water allocation problems in water resources management planning is studied to demonstrate the applicability of this method. Under different flow levels, different transferring measures are generated by this method when the promised water cannot be met. Moreover, interval solutions associated with different transferring costs also have been provided. They can be used for generating decision alternatives and thus help water resources managers to identify desired policies. Compared with the ITSP method, the IB-ITSP model can provide a positive measure for solving water shortage problems and afford useful information for decision makers under uncertainty.

Flight motor set 360L007 (STS-33R)

NASA Technical Reports Server (NTRS)

Garecht, Diane

1990-01-01

Flight motor set 360L007 was launched as part of NASA space shuttle mission STS-33R. As with all previous redesigned solid rocket motor launches, overall motor performance was excellent. There were no debris concerns for either motor. Both motors exhibited unbonds on one factory joint weatherseal. All ballistics contract end item specification parameters were verified, with the exception of ignition interval and rise rates. Ignition interval and rise rates could not be verified due to the elimination of developmental flight instrumentation from fourth flight and subsequent, but the low sample rate data that were available showed nominal propulsion performance. All ballistic and mass property parameters closely matched the predicted values and were well within the required contract end item specification levels that could be assessed. All 108 Ground Environment Instrumentation (GEI) measurements performed properly throughout the prelaunch phase. Evaluation of the GEI measurements again verified thermal model analysis data and showed agreement with predicted environmental effects. No launch commit criteria thermal violations occurred. All joint heaters operated normally, but a high voltage reading was noted on the left hand aft heater, which was immediately determined to be a voltage sensor error and not a heater anomaly due to no current increase. Postflight inspection again verified superior performance of the insulation, phenolics, metal parts, and seals. Postflight evaluation indicated both nozzles performed as expected during flight. All combustion gas was contained by insulation in the field and case-to-nozzle joints.

Monitoring uterine activity during labor: a comparison of 3 methods.

PubMed

Euliano, Tammy Y; Nguyen, Minh Tam; Darmanjian, Shalom; McGorray, Susan P; Euliano, Neil; Onkala, Allison; Gregg, Anthony R

2013-01-01

Tocodynamometry (Toco; strain gauge technology) provides contraction frequency and approximate duration of labor contractions but suffers frequent signal dropout, necessitating repositioning by a nurse, and may fail in obese patients. The alternative invasive intrauterine pressure catheter (IUPC) is more reliable and adds contraction pressure information but requires ruptured membranes and introduces small risks of infection and abruption. Electrohysterography (EHG) reports the electrical activity of the uterus through electrodes placed on the maternal abdomen. This study compared all 3 methods of contraction detection simultaneously in laboring women. Upon consent, laboring women were monitored simultaneously with Toco, EHG, and IUPC. Contraction curves were generated in real-time for the EHG, and all 3 curves were stored electronically. A contraction detection algorithm was used to compare frequency and timing between methods. Seventy-three subjects were enrolled in the study; 14 were excluded due to hardware failure of 1 or more of the devices (n = 12) or inadequate data collection duration (n = 2). In comparison with the gold-standard IUPC, EHG performed significantly better than Toco with regard to the Contractions Consistency Index (CCI). The mean CCI for EHG was 0.88 ± 0.17 compared with 0.69 ± 0.27 for Toco (P < .0001). In contrast to Toco, EHG was not significantly affected by obesity. Toco does not correlate well with the gold-standard IUPC and fails more frequently in obese patients. EHG provides a reliable noninvasive alternative, regardless of body habitus. Copyright © 2013 Mosby, Inc. All rights reserved.

Monitoring uterine activity during labor: a comparison of three methods

PubMed Central

EULIANO, Tammy Y.; NGUYEN, Minh Tam; DARMANJIAN, Shalom; MCGORRAY, Susan P.; EULIANO, Neil; ONKALA, Allison; GREGG, Anthony R.

2012-01-01

Objective Tocodynamometry (Toco—strain gauge technology) provides contraction frequency and approximate duration of labor contractions, but suffers frequent signal dropout necessitating re-positioning by a nurse, and may fail in obese patients. The alternative invasive intrauterine pressure catheter (IUPC) is more reliable and adds contraction pressure information, but requires ruptured membranes and introduces small risks of infection and abruption. Electrohysterography (EHG) reports the electrical activity of the uterus through electrodes placed on the maternal abdomen. This study compared all three methods of contraction detection simultaneously in laboring women. Study Design Upon consent, laboring women were monitored simultaneously with Toco, EHG, and IUPC. Contraction curves were generated in real-time for the EHG and all three curves were stored electronically. A contraction detection algorithm was used to compare frequency and timing between methods. Seventy-three subjects were enrolled in the study; 14 were excluded due to hardware failure of one or more of the devices (12) or inadequate data collection duration(2). Results In comparison with the gold-standard IUPC, EHG performed significantly better than Toco with regard to Contractions Consistency Index (CCI). The mean CCI for EHG was 0.88 ± 0.17 compared to 0.69 ± 0.27 for Toco (p<.0001). In contrast to Toco, EHG was not significantly affected by obesity. Conclusion Toco does not correlate well with the gold-standard IUPC and fails more frequently in obese patients. EHG provides a reliable non-invasive alternative regardless of body habitus. PMID:23122926

Size, History-Dependent, Activation and Three-Dimensional Effects on the Work and Power Produced During Cyclic Muscle Contractions.

PubMed

Ross, Stephanie A; Ryan, David S; Dominguez, Sebastian; Nigam, Nilima; Wakeling, James M

2018-05-03

Muscles undergo cycles of length change and force development during locomotion, and these contribute to their work and power production to drive body motion. Muscle fibres are typically considered to be linear actuators whose stress depends on their length, velocity, and activation state, and whose properties can be scaled up to explain the function of whole muscles. However, experimental and modelling studies have shown that a muscle's stress additionally depends on inactive and passive tissues within the muscle, the muscle's size, and its previous contraction history. These effects have not been tested under common sets of contraction conditions, especially the cyclic contractions that are typical of locomotion. Here we evaluate the relative effects of size, history-dependent, activation and three-dimensional effects on the work and power produced during cyclic contractions of muscle models. Simulations of muscle contraction were optimized to generate high power outputs: this resulted in the muscle models being largely active during shortening, and inactive during lengthening. As such, the history-dependent effects were dominated by force depression during simulated active shortening rather than force enhancement during active stretch. Internal work must be done to deform the muscle tissue, and to accelerate the internal muscle mass, resulting in reduced power and work that can be done on an external load. The effect of the muscle mass affects the scaling of muscle properties, with the inertial costs of contraction being relatively greater at larger sizes and lower activation levels.

[Computer cardiokymography. On its way to long-term noninvasive monitoring of cardiac performance in daly life].

PubMed

Khaiutin, V M; Lukoshkova, E V; Sheroziia, G G

2004-05-01

A functioning heart generates low-frequency and low-amplitude movements (up to 40 (mrn) of soft tissues in the percardial area. Since the 1950-s of the XX-th century cardiologists have studied these movements to employ them in the diagnostics of ischemic heart disease (IHD). Indeed, changes of the movements have found their diagnostic application in this field. If blood supply to a certain area of ventricular myocardium is insufficient the contractions in this area diminish and even ceases. After systolic increase in ventricular pressure this area dilates and forces intercostal tissues out, causing a "bulge" wave on the record. For recording the patient must be in supine position and hold the breath. High frequency electromagnetic field generator was used in an attempt to examine the heart movements. It was found that such instrument measures the thickness of the air-gap that serves as a dielectric or a "capacitor" which forms between the skin and approaching it flat inductive coil. Nevertheless, such an instrument (cardiokymograph, CKG) can reveal changes in contractions of ischemic myocardium and markedly increases the sensitivity of the exercise ECG test. However, CKG can be recorded only after termination of the test. This principal disadvantage has been overcome by software that allowed the recording of CKG during the test. A low-frequency capacitance transducer developed recently by Chinese researchers has provided a simultaneous recording of several CKG. After modifying the transducer, we have established that 1) the shape of CKGs is the same as that CKGs recorded by all our predecessors, 2) CKGs are reproducible even within a 3-month interval, 3) the enormous mechanical interference caused by respiratory movements and, to a greater extent, by the vigorous movements of the legs and trunk during veloergometry can be eliminated by digital processing of the transducer signals, and 4) pathological changes appear in CKG of patients with IHD, which enables one to stop veloergometry at lower loads, thus increasing the safety of the test. Since for large medical insurance companies very simple and inexpensive cardiokymograph are quite unprofitable, their commercially production in USA and in Germany has been stopped. However, the goal of cardiokymography: a real-time, beat-to-beat, long-term monitoring of cardiac function in daily life, remains the major factor determining the future of the method.

Heterogeneous CPA sensitivity of spontaneous excitation in smooth muscle of the rabbit urethra.

PubMed

Hashitani, Hikaru; Yanai, Yoshimasa; Kohri, Kenjiro; Suzuki, Hikaru

2006-06-01

1. To investigate the role of intracellular Ca stores in generating spontaneous excitation of the urethra, the effects of cyclopiazonic acid (CPA) on spontaneous contractions, transient increases in intracellular calcium concentration ([Ca2+]i; Ca transients) and depolarizations were examined in smooth muscles of the rabbit urethra. 2. In about 90% of circular smooth muscle (CSM) preparations, CPA (10 microM) increased the amplitude of spontaneous contractions by about 180% and reduced their frequency to some 25% of control values (CPA-resistant), while it readily abolished the contractions in the remaining preparations. 3. In about 70% of CSM preparations, CPA prevented the generation of spontaneous depolarizations termed slow waves, but increased their amplitude and duration in the remainder. CPA also prevented the generation of spontaneous Ca transients in about 40% of CSM preparations, while increasing their amplitude and duration in the remaining preparations. In CPA-resistant preparations that had been exposed to nicardipine (1 microM), subsequent CPA invariably abolished residual spontaneous depolarizations or Ca transients. CPA abolished caffeine-induced Ca transients in Ca-free solutions, suggesting that it effectively depleted intracellular Ca stores. 4. Longitudinal smooth muscles generated spontaneous action potentials, which had a shape distinct from that of slow waves in CSM. Spontaneous action potentials were abolished by nicardipine but not CPA. 5. Transmural nerve stimulation increased the frequency of Ca transients to give a sustained rise in [Ca2+]i, but inhibited their generation after blocking alpha-adrenoceptors with phentolamine (1 microM). These nerve-evoked responses were preserved in preparations that had been exposed to CPA. Similarly, both in control and CPA-treated CSM preparations, spontaneous Ca transients were accelerated by noradrenaline (NAd, 1 microM) and were suppressed by 3-morpholino-sydnonimine (SIN-1, 10 microM), a nitric oxide (NO) donor. 6. In conclusion, CSM of the urethra generates spontaneous activity, which depends on Ca release from intracellular Ca stores. However, after blocking this primary pacemaking mechanism, L-type Ca channel-dependent action potentials may drive CSM. Irrespective of the origin of pacemaking, neurally-released NAd and NO are capable of modulating spontaneous excitation.

Differential Motor Unit Changes after Endurance or High-Intensity Interval Training.

PubMed

Martinez-Valdes, Eduardo; Falla, Deborah; Negro, Francesco; Mayer, Frank; Farina, Dario

2017-06-01

Using a novel technique of high-density surface EMG decomposition and motor unit (MU) tracking, we compared changes in the properties of vastus medialis and vastus lateralis MU after endurance (END) and high-intensity interval training (HIIT). Sixteen men were assigned to the END or the HIIT group (n = 8 each) and performed six training sessions for 14 d. Each session consisted of 8-12 × 60-s intervals at 100% peak power output separated by 75 s of recovery (HIIT) or 90-120 min continuous cycling at ~65% V˙O2peak (END). Pre- and postintervention, participants performed 1) incremental cycling to determine V˙O2peak and peak power output and 2) maximal, submaximal (10%, 30%, 50%, and 70% maximum voluntary contraction [MVC]), and sustained (until task failure at 30% MVC) isometric knee extensions while high-density surface EMG signals were recorded from the vastus medialis and vastus lateralis. EMG signals were decomposed (submaximal contractions) into individual MU by convolutive blind source separation. Finally, MU were tracked across sessions by semiblind source separation. After training, END and HIIT improved V˙O2peak similarly (by 5.0% and 6.7%, respectively). The HIIT group showed enhanced maximal knee extension torque by ~7% (P = 0.02) and was accompanied by an increase in discharge rate for high-threshold MU (≥50% knee extension MVC) (P < 0.05). By contrast, the END group increased their time to task failure by ~17% but showed no change in MU discharge rates (P > 0.05). HIIT and END induce different adjustments in MU discharge rate despite similar improvements in cardiopulmonary fitness. Moreover, the changes induced by HIIT are specific for high-threshold MU. For the first time, we show that HIIT and END induce specific neuromuscular adaptations, possibly related to differences in exercise load intensity and training volume.

Fiber networks amplify active stress

NASA Astrophysics Data System (ADS)

Lenz, Martin; Ronceray, Pierre; Broedersz, Chase

Large-scale force generation is essential for biological functions such as cell motility, embryonic development, and muscle contraction. In these processes, forces generated at the molecular level by motor proteins are transmitted by disordered fiber networks, resulting in large-scale active stresses. While fiber networks are well characterized macroscopically, this stress generation by microscopic active units is not well understood. I will present a comprehensive theoretical study of force transmission in these networks. I will show that the linear, small-force response of the networks is remarkably simple, as the macroscopic active stress depends only on the geometry of the force-exerting unit. In contrast, as non-linear buckling occurs around these units, local active forces are rectified towards isotropic contraction and strongly amplified. This stress amplification is reinforced by the networks' disordered nature, but saturates for high densities of active units. I will show that our predictions are quantitatively consistent with experiments on reconstituted tissues and actomyosin networks, and that they shed light on the role of the network microstructure in shaping active stresses in cells and tissue.

Effect of red bull energy drink on auditory reaction time and maximal voluntary contraction.

PubMed

Goel, Vartika; Manjunatha, S; Pai, Kirtana M

2014-01-01

The use of "Energy Drinks" (ED) is increasing in India. Students specially use these drinks to rejuvenate after strenuous exercises or as a stimulant during exam times. The most common ingredient in EDs is caffeine and a popular ED available and commonly used is Red Bull, containing 80 mg of caffeine in 250 ml bottle. The primary aim of this study was to investigate the effects of Red Bull energy drink on Auditory reaction time and Maximal voluntary contraction. A homogeneous group containing twenty medical students (10 males, 10 females) participated in a crossover study in which they were randomized to supplement with Red Bull (2 mg/kg body weight of caffeine) or isoenergetic isovolumetric noncaffeinated control drink (a combination of Appy Fizz, Cranberry juice and soda) separated by 7 days. Maximal voluntary contraction (MVC) was recorded as the highest of the 3 values of maximal isometric force generated from the dominant hand using hand grip dynamometer (Biopac systems). Auditory reaction time (ART) was the average of 10 values of the time interval between the click sound and response by pressing the push button using hand held switch (Biopac systems). The energy and control drinks after one hour of consumption significantly reduced the Auditory reaction time in males (ED 232 ± 59 Vs 204 ± 34 s and Control 223 ± 57 Vs 210 ± 51 s; p < 0.05) as well as in females (ED 227 ± 56 Vs 214 ± 48 s and Control 224 ± 45 Vs 215 ± 36 s; p < 0.05) but had no effect on MVC in either sex (males ED 381 ± 37 Vs 371 ± 36 and Control 375 ± 61 Vs 363 ± 36 Newton, females ED 227 ± 23 Vs 227 ± 32 and Control 234 ± 46 Vs 228 ± 37 Newton). When compared across the gender groups, there was no significant difference between males and females in the effects of any of the drinks on the ART but there was an overall significantly lower MVC in females compared to males. Both energy drink and the control drink significantly improve the reaction time but may not have any effect on muscular performance. Energy drink per se is no better than control drink, which may indicate that there is no role of caffeine in the beneficial effect seen after the drinks.

The Millennial Generation: Howe and Strauss Disputed

ERIC Educational Resources Information Center

Alexander Agati, Holly

2012-01-01

Researchers have attempted to untangle the complexity of a generation through four primary effects--time interval, cohort, period, and attitude--based on personal and societal attributes. The Millennial generation, born 1982-2000, has received considerable attention through the media, in educational institutions, and in the workplace. The seven…

Delayed interval delivery in multiple gestations.

PubMed

Platt, J S; Rosa, C

1999-05-01

The incidence of higher-order gestations is increasing primarily as a result of menstrual cycle manipulation, with concomitant increased risk in maternal and fetal complications. Perinatal mortality rates range between 47 and 120 per 1000 births for twins and 93 to 203 per 1000 births for triplets. The critical period of perinatal mortality and morbidity is between weeks 23 and 28 of gestation. Attention has recently turned to methods of delaying the birth of second and higher order fetuses to improve newborn survival and decrease neonatal morbidity in these high-risk pregnancies. We report two cases of delayed interval delivery. Neither pregnancy involved a monochorionic/monoamniotic gestation. The first case was a twin gestation delivered at 21 weeks with an interval of 5 days and extreme prematurity of both twins. The second case was a triplet gestation delivered at 21 weeks with an interval of 5 days. Triplet A was stillborn; triplets B and C succumbed in extreme prematurity. Preterm labor in multiple gestations usually results in delivery of all fetuses. On occasion, the uterus will spontaneously cease to contract after the birth of one or more premature infants. Review of the literature now reports 48 twin pregnancies exposed to delayed interval delivery with 40 surviving infants of 96 fetuses. Whereas delaying the delivery of remaining fetuses improves their prognosis, there is currently no consensus regarding technique nor is there statistical significance in techniques currently used. Furthermore, study is indicated to reduce preterm birth and associated costs.

Inconsistencies in Numerical Simulations of Dynamical Systems Using Interval Arithmetic

NASA Astrophysics Data System (ADS)

Nepomuceno, Erivelton G.; Peixoto, Márcia L. C.; Martins, Samir A. M.; Rodrigues, Heitor M.; Perc, Matjaž

Over the past few decades, interval arithmetic has been attracting widespread interest from the scientific community. With the expansion of computing power, scientific computing is encountering a noteworthy shift from floating-point arithmetic toward increased use of interval arithmetic. Notwithstanding the significant reliability of interval arithmetic, this paper presents a theoretical inconsistency in a simulation of dynamical systems using a well-known implementation of arithmetic interval. We have observed that two natural interval extensions present an empty intersection during a finite time range, which is contrary to the fundamental theorem of interval analysis. We have proposed a procedure to at least partially overcome this problem, based on the union of the two generated pseudo-orbits. This paper also shows a successful case of interval arithmetic application in the reduction of interval width size on the simulation of discrete map. The implications of our findings on the reliability of scientific computing using interval arithmetic have been properly addressed using two numerical examples.

Metabolic adaptations to repeated periods of contraction with reduced blood flow in canine skeletal muscle

PubMed Central

MacInnes, Alan; Timmons, James A

2005-01-01

Background Patients suffering from Intermittent Claudication (IC) experience repeated periods of muscle contraction with low blood flow, throughout the day and this may contribute to the hypothesised skeletal muscle abnormalities. However, no study has evaluated the consequences of intermittent contraction with low blood flow on skeletal muscle tissue. Our aim was to generate this basic physiological data, determining the 'normal' response of healthy skeletal muscle tissue. We specifically proposed that the metabolic responses to contraction would be modified under such circumstances, revealing endogenous strategies engaged to protect the muscle adenine nucleotide pool. Utilizing a canine gracilis model (n = 9), the muscle was stimulated to contract (5 Hz) for three 10 min periods (separated by 10 min rest) under low blood flow conditions (80% reduced), followed by 1 hr recovery and then a fourth period of 10 min stimulation. Muscle biopsies were obtained prior to and following the first and fourth contraction periods. Direct arterio-venous sampling allowed for the calculation of muscle metabolite efflux and oxygen consumption. Results During the first period of contraction, [ATP] was reduced by ~30%. During this period there was also a 10 fold increase in muscle lactate concentration and a substantial increase in muscle lactate and ammonia efflux. Subsequently, lactate efflux was similar during the first three periods, while ammonia efflux was reduced by the third period. Following 1 hr recovery, muscle lactate and phosphocreatine concentrations had returned to resting values, while muscle [ATP] remained 20% lower. During the fourth contraction period no ammonia efflux or change in muscle ATP content occured. Despite such contrasting metabolic responses, muscle tension and oxygen consumption were identical during all contraction periods from 3 to 10 min. Conclusion repeated periods of muscle contraction, with low blood flow, results in cessation of muscle ammonia production which is suggestive of a dramatic reduction in flux through AMP deaminase. PMID:16018808

Titanium Dioxide Modulation of the Contractibility of Visceral Smooth Muscles In Vivo

NASA Astrophysics Data System (ADS)

Tsymbalyuk, Olga V.; Naumenko, Anna M.; Rohovtsov, Oleksandr O.; Skoryk, Mykola A.; Voiteshenko, Ivan S.; Skryshevsky, Valeriy A.; Davydovska, Tamara L.

2017-02-01

Electronic scanning microscopy was used in the work to obtain the image and to identify the sizes of titanium dioxide (TiO2) nanoparticles 21 ± 5 nm. The qualitative and quantitative elemental analysis of the preparations of the caecum, antrum, myometrium, kidneys, and lungs of the rats, burdened with titanium dioxide, was also performed. It was established using the tenzometric method in the isometric mode that the accumulation of titanium dioxide in smooth muscles of the caecum resulted in the considerable, compared to the control, increase in the frequency of their spontaneous contractions, the decrease in the duration of the contraction-relaxation cycle, and the decrease in the indices of muscle functioning efficiency (the index of contractions in Montevideo units (MU) and the index of contractions in Alexandria units (AU)). In the same experimental conditions, there was not the increase, but the decrease in the frequency of spontaneous contractions, the duration of the contraction-relaxation cycle, and the increase in MU and AU indices in the smooth muscles of myometrium (in the group of rats, burdened with TiO2 for 30 days). It was also determined that TiO2 modulates both the mechanisms of the input of extracellular Ca2+ ions and the mechanisms of decreasing the concentration of these cations in smooth muscle cells of the caecum during the generation of the high potassium contraction. In these conditions, there is a considerable increase in the normalized maximal velocity of the contraction phase and the relaxation phase. It was demonstrated in the work that titanium dioxide also changes the cholinergic excitation in these muscles. The impact of titanium dioxide in the group of rats, burdened with TiO2, was accompanied with a considerable impairment of the kinetics of forming the tonic component of the oxytocin-induced contraction of the smooth muscles of myometrium.

Problem Variables that Promote Incubation Effects

ERIC Educational Resources Information Center

Penney, Catherine G.; Godsell, Annette; Scott, Annette; Balsom, Rod

2004-01-01

Three studies sought to determine whether incubation effects could be reliably generated in a problem-solving task. Experimental variables manipulated were the duration of the interval between two problem-solving opportunities and the activity performed by the problem solvers during the interval. A multisolution anagram task was used which…

High resolution data acquisition

DOEpatents

Thornton, G.W.; Fuller, K.R.

1993-04-06

A high resolution event interval timing system measures short time intervals such as occur in high energy physics or laser ranging. Timing is provided from a clock, pulse train, and analog circuitry for generating a triangular wave synchronously with the pulse train (as seen in diagram on patent). The triangular wave has an amplitude and slope functionally related to the time elapsed during each clock pulse in the train. A converter forms a first digital value of the amplitude and slope of the triangle wave at the start of the event interval and a second digital value of the amplitude and slope of the triangle wave at the end of the event interval. A counter counts the clock pulse train during the interval to form a gross event interval time. A computer then combines the gross event interval time and the first and second digital values to output a high resolution value for the event interval.

High resolution data acquisition

DOEpatents

Thornton, Glenn W.; Fuller, Kenneth R.

1993-01-01

A high resolution event interval timing system measures short time intervals such as occur in high energy physics or laser ranging. Timing is provided from a clock (38) pulse train (37) and analog circuitry (44) for generating a triangular wave (46) synchronously with the pulse train (37). The triangular wave (46) has an amplitude and slope functionally related to the time elapsed during each clock pulse in the train. A converter (18, 32) forms a first digital value of the amplitude and slope of the triangle wave at the start of the event interval and a second digital value of the amplitude and slope of the triangle wave at the end of the event interval. A counter (26) counts the clock pulse train (37) during the interval to form a gross event interval time. A computer (52) then combines the gross event interval time and the first and second digital values to output a high resolution value for the event interval.

Is walking a random walk? Evidence for long-range correlations in stride interval of human gait

NASA Technical Reports Server (NTRS)

Hausdorff, Jeffrey M.; Peng, C.-K.; Ladin, Zvi; Wei, Jeanne Y.; Goldberger, Ary L.

1995-01-01

Complex fluctuation of unknown origin appear in the normal gait pattern. These fluctuations might be described as being (1) uncorrelated white noise, (2) short-range correlations, or (3) long-range correlations with power-law scaling. To test these possibilities, the stride interval of 10 healthy young men was measured as they walked for 9 min at their usual rate. From these time series we calculated scaling indexes by using a modified random walk analysis and power spectral analysis. Both indexes indicated the presence of long-range self-similar correlations extending over hundreds of steps; the stride interval at any time depended on the stride interval at remote previous times, and this dependence decayed in a scale-free (fractallike) power-law fashion. These scaling indexes were significantly different from those obtained after random shuffling of the original time series, indicating the importance of the sequential ordering of the stride interval. We demonstrate that conventional models of gait generation fail to reproduce the observed scaling behavior and introduce a new type of central pattern generator model that sucessfully accounts for the experimentally observed long-range correlations.

Effects of pro-inflammatory cytokines, lipopolysaccharide and COX-2 mediators on human colonic neuromuscular function and epithelial permeability.

PubMed

Safdari, B K; Sia, T C; Wattchow, D A; Smid, S D

2016-07-01

Chronic colitis is associated with decreased colonic muscle contraction and loss of mucosal barrier function. Pro-inflammatory cytokines and bacterial lipopolysaccharide (LPS) are important in the generation and maintenance of inflammation. While colitis is associated with upregulated COX-2 -derived prostanoids and nitric oxide (NO), the direct activity of pro-inflammatory cytokines on human colonic neuromuscular function is less clear. This study investigated the effects of IBD-associated pro-inflammatory cytokines IL-17, TNF-α, IL-1β and LPS on human colonic muscle strip contractility, alone and following inhibition of COX-2 or nitric oxide production. In addition, human colonic epithelial Caco-2 cell monolayers were treated with LPS or COX-2 mediators including prostaglandins (PGE2, PGF2α) or their corresponding ethanolamides (PGE2-EA or PGF2α-EA) over 48h and trans-epithelial electrical resistance used to record permeability changes. Longitudinal muscle strips were obtained from healthy colonic resection margins and mounted in organ baths following IL-17, TNF-α, IL-1β and bacterial LPS incubations in an explant setting over 20h. Contraction in response to acetylcholine (ACh) was then measured, before and after either COX-2 inhibition (nimesulide; 10(-5)M) or nitric oxide synthase (NOS) inhibition (l-NNA; 10(-4)M). None of the cytokine or LPS explant incubations affected the potency or maximum cholinergic contraction in vitro, and subsequent COX-2 blockade with nimesulide revealed a significant but similar decrease in potency of ACh-evoked contraction in control, LPS and cytokine-incubated muscle strips. Pre-treatment with l-NNA provided no functional differences in the potency or maximum contractile responses to ACh in cytokine or LPS-incubated colonic longitudinal smooth muscle. Only PGE2 transiently increased Caco-2 monolayer permeability at 24h, while LPS (10μg/ml) increased permeability over 24-48h. These findings indicate that cholinergic contractility in the human colon can be decreased by the blockade of COX-2 generated excitatory prostanoids, but major pro-inflammatory cytokines or LPS do not alter the sensitivity or amplitude of this contraction ex vivo. While PGE2 transiently increase epithelial permeability, LPS generates a significant and sustained increase in permeability indicative of an important role on barrier function at the mucosal interface. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

48 CFR 23.703 - Policy.

Code of Federal Regulations, 2013 CFR

2013-10-01

... ENVIRONMENT, ENERGY AND WATER EFFICIENCY, RENEWABLE ENERGY TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE...) Implement cost-effective contracting preference programs promoting energy-efficiency, water conservation... energy-efficiency and water conservation. (3) Eliminate or reduce the generation of hazardous waste and...

48 CFR 23.703 - Policy.

Code of Federal Regulations, 2011 CFR

2011-10-01

... ENVIRONMENT, ENERGY AND WATER EFFICIENCY, RENEWABLE ENERGY TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE...) Implement cost-effective contracting preference programs promoting energy-efficiency, water conservation... energy-efficiency and water conservation. (3) Eliminate or reduce the generation of hazardous waste and...

48 CFR 23.703 - Policy.

Code of Federal Regulations, 2014 CFR

2014-10-01

... ENVIRONMENT, ENERGY AND WATER EFFICIENCY, RENEWABLE ENERGY TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE...) Implement cost-effective contracting preference programs promoting energy-efficiency, water conservation... energy-efficiency and water conservation. (3) Eliminate or reduce the generation of hazardous waste and...

48 CFR 23.703 - Policy.

Code of Federal Regulations, 2012 CFR

2012-10-01

... ENVIRONMENT, ENERGY AND WATER EFFICIENCY, RENEWABLE ENERGY TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE...) Implement cost-effective contracting preference programs promoting energy-efficiency, water conservation... energy-efficiency and water conservation. (3) Eliminate or reduce the generation of hazardous waste and...

A Best Practice for Developing Availability Guarantee Language in Photovoltaic (PV) O&M Agreements.

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

Klise, Geoffrey Taylor; Balfour, John

This document outlines the foundation for developing language that can be utilized in an Equipment Availability Guarantee, typically included in an O&M services agreement between a PV system or plant owner and an O&M services provider, or operator. Many of the current PV O&M service agreement Availability Guarantees are based on contracts used for traditional power generation, which create challenges for owners and operators due to the variable nature of grid-tied photovoltaic generating technologies. This report documents language used in early PV availability guarantees and presents best practices and equations that can be used to more openly communicate how themore » reliability of the PV system and plant equipment can be expressed in an availability guarantee. This work will improve the bankability of PV systems by providing greater transparency into the equipment reliability state to all parties involved in an O&M services contract.« less

Optimal investment horizons

NASA Astrophysics Data System (ADS)

Simonsen, I.; Jensen, M. H.; Johansen, A.

2002-06-01

In stochastic finance, one traditionally considers the return as a competitive measure of an asset, i.e., the profit generated by that asset after some fixed time span Δt, say one week or one year. This measures how well (or how bad) the asset performs over that given period of time. It has been established that the distribution of returns exhibits ``fat tails'' indicating that large returns occur more frequently than what is expected from standard Gaussian stochastic processes [1-3]. Instead of estimating this ``fat tail'' distribution of returns, we propose here an alternative approach, which is outlined by addressing the following question: What is the smallest time interval needed for an asset to cross a fixed return level of say 10%? For a particular asset, we refer to this time as the investment horizon and the corresponding distribution as the investment horizon distribution. This latter distribution complements that of returns and provides new and possibly crucial information for portfolio design and risk-management, as well as for pricing of more exotic options. By considering historical financial data, exemplified by the Dow Jones Industrial Average, we obtain a novel set of probability distributions for the investment horizons which can be used to estimate the optimal investment horizon for a stock or a future contract.