Sedimentary and Volcanic Records of the Laschamp and Mono Lake Excursions from Australia and New Zealand

NASA Astrophysics Data System (ADS)

Ingham, E. M.; Roberts, A. P.; Turner, G. M.; Heslop, D.; Ronge, T.; Conway, C.; Leonard, G.; Townsend, D.; Tiedemann, R.; Lamy, F.; Calvert, A. T.

2014-12-01

Geomagnetic excursions are short-lived deviations of the geomagnetic field from the normal range of secular variation. Despite significant advances in geomagnetic excursion research over the past 20 years, fundamental questions remain concerning the typical duration and global morphology of excursional geomagnetic fields. To answer such questions, more high-resolution, chronologically well-constrained excursion records are required, particularly from the Southern Hemisphere. We present preliminary paleomagnetic records of the Laschamp (~41 ka) and Mono Lake (~35 ka) excursions from three marine sediment cores from the Bounty Trough, New Zealand margin, and complementary volcanic records of the Laschamp excursion from lavas of Mt Ruapehu, New Zealand. Relatively high sedimentation rates of 12 - 26 cm/kyr in the Bounty Trough during glacial periods allow identification of excursional field behavior at each of the studied core locations. Each core displays one or two excursional events, with rapid directional swings between stable normal polarity and reversed excursional directions, each associated with coincident relative paleointensity minima. These anomalous paleomagnetic directions are interpreted to represent the Laschamp and Mono Lake excursions, based on a combination of tephrochronology, radiocarbon dating, and cyclostratigraphy (defined from core-scanning X-ray fluorescence and magnetic susceptibility records). Beside these records, we present results from fourteen lava flows, on Mt Ruapehu, for which 40Ar-39Ar dating indicates ages of between 39 and 45 ka. The step heating 40Ar-39Ar experiments produced particularly flat age plateaus, with corresponding 2 s.d. errors mostly approaching 1 kyr. The youngest and oldest flows carry normal polarity magnetization, however six flows, dated between 41 and 43 ka, display transitional field characteristics. Three of these flows display a declination swing of around 180o, which coincides with a previously published result from the Auckland Basalt Field. Together, these data provide rare excursion records from the southern hemisphere, which will provide an improved view of geomagnetic field morphology during these excursions.

The statistical overlap theory of chromatography using power law (fractal) statistics.

PubMed

Schure, Mark R; Davis, Joe M

2011-12-30

The chromatographic dimensionality was recently proposed as a measure of retention time spacing based on a power law (fractal) distribution. Using this model, a statistical overlap theory (SOT) for chromatographic peaks is developed that estimates the number of peak maxima as a function of the chromatographic dimension, saturation and scale. Power law models exhibit a threshold region whereby below a critical saturation value no loss of peak maxima due to peak fusion occurs as saturation increases. At moderate saturation, behavior is similar to the random (Poisson) peak model. At still higher saturation, the power law model shows loss of peaks nearly independent of the scale and dimension of the model. The physicochemical meaning of the power law scale parameter is discussed and shown to be equal to the Boltzmann-weighted free energy of transfer over the scale limits. The scale is discussed. Small scale range (small β) is shown to generate more uniform chromatograms. Large scale range chromatograms (large β) are shown to give occasional large excursions of retention times; this is a property of power laws where "wild" behavior is noted to occasionally occur. Both cases are shown to be useful depending on the chromatographic saturation. A scale-invariant model of the SOT shows very simple relationships between the fraction of peak maxima and the saturation, peak width and number of theoretical plates. These equations provide much insight into separations which follow power law statistics. Copyright © 2011 Elsevier B.V. All rights reserved.

The effects of texting on driving performance in a driving simulator: the influence of driver age.

PubMed

Rumschlag, Gordon; Palumbo, Theresa; Martin, Amber; Head, Doreen; George, Rajiv; Commissaris, Randall L

2015-01-01

Distracted driving is a significant contributor to motor vehicle accidents and fatalities, and texting is a particularly significant form of driver distraction that continues to be on the rise. The present study examined the influence of driver age (18-59 years old) and other factors on the disruptive effects of texting on simulated driving behavior. While 'driving' the simulator, subjects were engaged in a series of brief text conversations with a member of the research team. The primary dependent variable was the occurrence of Lane Excursions (defined as any time the center of the vehicle moved outside the directed driving lane, e.g., into the lane for oncoming traffic or onto the shoulder of the road), measured as (1) the percent of subjects that exhibited Lane Excursions, (2) the number of Lane Excursions occurring and (3) the percent of the texting time in Lane Excursions. Multiple Regression analyses were used to assess the influence of several factors on driving performance while texting, including text task duration, texting skill level (subject-reported), texting history (#texts/week), driver gender and driver age. Lane Excursions were not observed in the absence of texting, but 66% of subjects overall exhibited Lane Excursions while texting. Multiple Regression analysis for all subjects (N=50) revealed that text task duration was significantly correlated with the number of Lane Excursions, and texting skill level and driver age were significantly correlated with the percent of subjects exhibiting Lane Excursions. Driver gender was not significantly correlated with Lane Excursions during texting. Multiple Regression analysis of only highly skilled texters (N=27) revealed that driver age was significantly correlated with the number of Lane Excursions, the percent of subjects exhibiting Lane Excursions and the percent of texting time in Lane Excursions. In contrast, Multiple Regression analysis of those drivers who self-identified as not highly skilled texters (N=23) revealed that text task duration was significantly correlated with the number of Lane Excursions. The present studies confirm past reports that texting impairs driving simulator performance. Moreover, the present study demonstrates that for highly skilled texters, the effects of texting on driving are actually worse for older drivers. Given the increasing frequency of texting while driving within virtually all age groups, these data suggest that 'no texting while driving' education and public service messages need to be continued, and they should be expanded to target older drivers as well. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of numerical dissipation and unphysical excursions on scalar-mixing estimates in large-eddy simulations

NASA Astrophysics Data System (ADS)

Sharan, Nek; Matheou, Georgios; Dimotakis, Paul

2017-11-01

Artificial numerical dissipation decreases dispersive oscillations and can play a key role in mitigating unphysical scalar excursions in large eddy simulations (LES). Its influence on scalar mixing can be assessed through the resolved-scale scalar, Z , its probability density function (PDF), variance, spectra, and the budget of the horizontally averaged equation for Z2. LES of incompressible temporally evolving shear flow enabled us to study the influence of numerical dissipation on unphysical scalar excursions and mixing estimates. Flows with different mixing behavior, with both marching and non-marching scalar PDFs, are studied. Scalar fields for each flow are compared for different grid resolutions and numerical scalar-convection term schemes. As expected, increasing numerical dissipation enhances scalar mixing in the development stage of shear flow characterized by organized large-scale pairings with a non-marching PDF, but has little influence in the self-similar stage of flows with marching PDFs. Flow parameters and regimes sensitive to numerical dissipation help identify approaches to mitigate unphysical excursions while minimizing dissipation.

Estimates of the effectiveness of automatic control in alleviating wake vortex induced roll excursions

NASA Technical Reports Server (NTRS)

Tinling, B. E.

1977-01-01

Estimates of the effectiveness of a model following type control system in reducing the roll excursion due to a wake vortex encounter were obtained from single degree of freedom computations with inputs derived from the results of wind tunnel, flight, and simulation experiments. The analysis indicates that the control power commanded by the automatic system must be roughly equal to the vortex induced roll acceleration if effective limiting of the maximum bank angle is to be achieved.

An 84-kyr paleomagnetic record from the sediments of Lake Baikal, Siberia

USGS Publications Warehouse

Peck, J.A.; King, J.W.; Colman, Steven M.; Kravchinsky, V.A.

1996-01-01

We have conducted a paleomagnetic study of sediment cores obtained from the Selenga prodelta region of Lake Baikal, Russia. This record, which spans approximately the last 84 kyr, contributes to a better understanding of the nature of geomagnetic field behavior in Siberia and is a useful correlation and dating tool. We demonstrate that the Lake Baikal sediments are recording variations in the geomagnetic field. The directional record displays secular variation behavior with a geomagnetic excursion at 20 ka and additional excursions appearing as large-amplitude secular variation at 41, 61, and 67 ka. Smoothing of the geomagnetic excursion behavior occurs in Lake Baikal sediments owing to the intermediate sedimentation rate (13 cm kyr-1). The Lake Baikal relative paleointensity record correlates to absolute paleointensity data for the last 10 kyr and to relative paleointensity records from the Mediterranean Sea and Indian Ocean for the last 84 kyr. This correlation suggests a strong global (i.e., dipole) component to these records and further supports the reliability of sediments as recorders of relative geomagnetic paleointensity. We show that a relative geomagnetic intensity stratigraphy has a potential resolution of 7 kyr by correlating continental and marine records. The geomagnetic intensity stratigraphy helps constrain the age of the difficult to date Lake Baikal sediments.

Transient boiling in two-phase helium natural circulation loops

NASA Astrophysics Data System (ADS)

Furci, H.; Baudouy, B.; Four, A.; Meuris, C.

2014-01-01

Two-phase helium natural circulation loops are used for cooling large superconducting magnets, as CMS for LHC. During normal operation or in the case of incidents, transients are exerted on the cooling system. Here a cooling system of this type is studied experimentally. Sudden power changes are operated on a vertical-heated-section natural convection loop, simulating a fast increase of heat deposition on magnet cooling pipes. Mass flow rate, heated section wall temperature and pressure drop variations are measured as a function of time, to assess the time behavior concerning the boiling regime according to the values of power injected on the heated section. The boiling curves and critical heat flux (CHF) values have been obtained in steady state. Temperature evolution has been observed in order to explore the operating ranges where heat transfer is deteriorated. Premature film boiling has been observed during transients on the heated section in some power ranges, even at appreciably lower values than the CHF. A way of attenuating these undesired temperature excursions has been identified through the application of high enough initial heating power.

Differences and similarities in cross-cultural perceptions of boundaries: a comparison of results from two studies.

PubMed

Miller, Patrice Marie; Bener, Abdulbari; Ghuloum, Suhaila; Commons, Michael Lamport; Burgut, F Tuna

2012-01-01

There has been substantial literature on boundary excursions in clinician-patient relationships; however, very little empirical research exists. Even less information exists on how perceptions of this issue might differ across cultures. Prior to this study, empirical data on various kinds of boundary excursions were collected in different cultural contexts. First, clinicians from the U.S. and Brazil were asked to rate 173 boundary excursions for both their perceived harmfulness and their professional unacceptability (Miller et al., 2006). In a second study, colleagues from Qatar administered a slightly modified version to mental health care professional staff of a hospital in Doha, Qatar (Ghuloum et al., 2011). In this paper, the results of these two separate studies are compared. The results showed some similarities and some differences in perceptions of the boundary behaviors. For example, both sets of cultures seem to agree that certain behaviors are seriously harmful and/or professionally unacceptable. These behaviors include some frankly sexual behavior, such as having sexual intercourse with a patient, as well as behavior related to doing business with the patient, and some disclosing behavior. There are also significant cultural differences in perceptions of how harmful some of the behaviors are. Qatari practitioners seemed to rate certain behaviors that within therapy mix disclosing or personal behavior with therapy as more harmful, but behaviors that involved interacting with patients outside of therapy as less serious. A factor analysis suggested that participants in U.S./Brazil saw a much larger number of behaviors as making up a set of Core Boundary Violations, whereas Qatari respondents separated sexual behaviors from others. Finally, a Rasch analysis showed that both cultures perceived a continuum of boundary behaviors, from those that are least harmful or unprofessional to those that are highly harmful or unprofessional. One interpretation is that cultural factors may be most influential on those kinds of behaviors that are perceived as relatively less serious. Implications for training and supervision are also discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Earth's magnetic field is probably not reversing.

PubMed

Brown, Maxwell; Korte, Monika; Holme, Richard; Wardinski, Ingo; Gunnarson, Sydney

2018-05-15

The geomagnetic field has been decaying at a rate of ∼5% per century from at least 1840, with indirect observations suggesting a decay since 1600 or even earlier. This has led to the assertion that the geomagnetic field may be undergoing a reversal or an excursion. We have derived a model of the geomagnetic field spanning 30-50 ka, constructed to study the behavior of the two most recent excursions: the Laschamp and Mono Lake, centered at 41 and 34 ka, respectively. Here, we show that neither excursion demonstrates field evolution similar to current changes in the geomagnetic field. At earlier times, centered at 49 and 46 ka, the field is comparable to today's field, with an intensity structure similar to today's South Atlantic Anomaly (SAA); however, neither of these SAA-like fields develop into an excursion or reversal. This suggests that the current weakened field will also recover without an extreme event such as an excursion or reversal. The SAA-like field structure at 46 ka appears to be coeval with published increases in geomagnetically modulated beryllium and chlorine nuclide production, despite the global dipole field not weakening significantly in our model during this time. This agreement suggests a greater complexity in the relationship between cosmogenic nuclide production and the geomagnetic field than is commonly assumed.

Paleomagnetic Results From the Pleistocene Sediments of Lomonosov Ridge, Central Artic Ocean, IODP Leg 302

NASA Astrophysics Data System (ADS)

King, J. W.; Heil, C.; O'Regan, M.; Moran, K.; Gattacecca, J.; Backman, J.; Jakobsson, M.; Moore, T.

2005-12-01

Two major conclusions can be drawn from magnetic studies of Pleistocene sediments drilled on Lomonosov Ridge, central Arctic Ocean during IODP Leg 302. The first conclusion is that central Arctic Ocean sedimentation rates approach 2 cm/ka during the Pleistocene, thereby resolving the Arctic sedimentation rate controversy in favor of "fast" rates. The second conclusion is that abundant broad intervals of reversed polarity during the Pleistocene are a consistent characteristic of Arctic sedimentary records. These broad reversed intervals have helped perpetuate the Arctic sedimentation rate controversy. The weight of evidence strongly indicates that these reversal intervals are excursions. They do not occur during the late Brunhes Epoch (approximately 0-250,000 BP), but occur during the mid to lower Brunhes Epoch and persist into the upper Matuyama Epoch. We observe a strong correlation between rock magnetic variations, color changes, and physical property stratigraphy and these excursions. The model for Arctic sedimentation indicates that the excursions primarily occur during "interglacial" intervals. Previous high quality paleomagnetic studies of Bermuda Rise sediments have shown that approximately 85 % of Brunhes age excursions occur during interglacial periods (Lund, et al., 2001). In addition, similar excursions do not appear to occur at high southern latitudes (e.g. Acton, et al., 2002). For these reasons, we feel that hypotheses that attribute the interesting observed Arctic paleomagnetic behavior to environmental controls (e.g. sedimentation processes) are favored over those involving geomagnetic field behavior within the tangent cylinder. Acton, G. D., Guyodo, Y., and S. A. Brachfeld, 2002. Magnetostratigraphy of sediment drifts on the continental rise of West Antarctica (ODP Leg 178, Sites 1095, 1096, and 1101). In Barker, P. F., Camerlenghi, A., Acton, G. D., and Ramsay, A.T.S (Eds.), Proc. ODP Sci. Results, v. 178; 1-61 (CD ROM). Lund, S. P., G. D. Acton, B. Clement, M. Okada, and T. Williams. 2001. Brunhes chron magnetics excursions recovered from Leg 172 sediments. In Keigwin, L. D., Rio, D., Acton, G. D., and Arnold, E., (eds.) Proc. ODP Sci. Results, v. 172; p. 1-18 (Online)

Downflow dryout in a heated ribbed vertical annulus with a cosine power profile (Results from test series ECS-2, WSR, and ECS-2cE)

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

Larson, T.K.; Anderson, J.L.; Condie, K.G.

Experiments designed to investigate surface dryout in a heated, ribbed annulus test section simulating one of the annular coolant channels of a Savannah River Plant production reactor Mark 22 fuel assembly have been conducted at the Idaho National Engineering Laboratory. The inner surface of the annulus was constructed of aluminum and was electrically heated to provide an axial cosine power profile and a flat azimuthal power shape. Data presented in this report are from the ECS-2, WSR, and ECS-2cE series of tests. These experiments were conducted to examine the onset of wall thermal excursion for a range of flow, inletmore » fluid temperature, and annulus outlet pressure. Hydraulic boundary conditions on the test section represent flowrates (0.1--1.4 1/s), inlet fluid temperatures (293--345 K), and outlet pressures (-18--139.7 cm of water relative to the bottom of the heated length (61--200 cm of water relative to the bottom of the lower plenum)) expected to occur during the Emergency Coolant System (ECS) phase of postulated Loss-of-Coolant Accident in a production reactor. The onset of thermal excursion based on the present data is consistent with data gathered in test rigs with flat axial power profiles. The data indicate that wall dryout is primarily a function of liquid superficial velocity. Air entrainment rate was observed to be a strong function of the boundary conditions (primarily flowrate and liquid temperature), but had a minor effect on the power at the onset of thermal excursion for the range of conditions examined. 14 refs., 33 figs., 13 tabs.« less

Advanced Plasma Propulsion for Human Missions to Jupiter

NASA Technical Reports Server (NTRS)

Donahue, Benjamin B.; Pearson, J. Boise

1999-01-01

This paper will briefly identify a promising fusion plasma power source, which when coupled with a promising electric thruster technology would provide for an efficient interplanetary transfer craft suitable to a 4 year round trip mission to the Jovian system. An advanced, nearly radiation free Inertial Electrostatic Confinement scheme for containing fusion plasma was judged as offering potential for delivering the performance and operational benefits needed for such high energy human expedition missions, without requiring heavy superconducting magnets for containment of the fusion plasma. Once the Jovian transfer stage has matched the heliocentric velocity of Jupiter, the energy requirements for excursions to its outer satellites (Callisto, Ganymede and Europa) by smaller excursion craft are not prohibitive. The overall propulsion, power and thruster system is briefly described and a preliminary vehicle mass statement is presented.

Epaxial muscle fiber architecture favors enhanced excursion and power in the leaper Galago senegalensis

PubMed Central

Huq, Emranul; Wall, Christine E; Taylor, Andrea B

2015-01-01

Galago senegalensis is a habitual arboreal leaper that engages in rapid spinal extension during push-off. Large muscle excursions and high contraction velocities are important components of leaping, and experimental studies indicate that during leaping by G. senegalensis, peak power is facilitated by elastic storage of energy. To date, however, little is known about the functional relationship between epaxial muscle fiber architecture and locomotion in leaping primates. Here, fiber architecture of select epaxial muscles is compared between G. senegalensis (n = 4) and the slow arboreal quadruped, Nycticebus coucang (n = 4). The hypothesis is tested that G. senegalensis exhibits architectural features of the epaxial muscles that facilitate rapid and powerful spinal extension during the take-off phase of leaping. As predicted, G. senegalensis epaxial muscles have relatively longer, less pinnate fibers and higher ratios of tendon length-to-fiber length, indicating the capacity for generating relatively larger muscle excursions, higher whole-muscle contraction velocities, and a greater capacity for elastic energy storage. Thus, the relatively longer fibers and higher tendon length-to-fiber length ratios can be functionally linked to leaping performance in G. senegalensis. It is further predicted that G. senegalensis epaxial muscles have relatively smaller physiological cross-sectional areas (PCSAs) as a consequence of an architectural trade-off between fiber length (excursion) and PCSA (force). Contrary to this prediction, there are no species differences in relative PCSAs, but the smaller-bodied G. senegalensis trends towards relatively larger epaxial muscle mass. These findings suggest that relative increase in muscle mass in G. senegalensis is largely attributable to longer fibers. The relative increase in erector spinae muscle mass may facilitate sagittal flexibility during leaping. The similarity between species in relative PCSAs provides empirical support for previous work linking osteological features of the vertebral column in lorisids with axial stability and reduced muscular effort associated with slow, deliberate movements during anti-pronograde locomotion. PMID:26184388

Gravitational dynamos and the low-frequency geomagnetic secular variation.

PubMed

Olson, P

2007-12-18

Self-sustaining numerical dynamos are used to infer the sources of low-frequency secular variation of the geomagnetic field. Gravitational dynamo models powered by compositional convection in an electrically conducting, rotating fluid shell exhibit several regimes of magnetic field behavior with an increasing Rayleigh number of the convection, including nearly steady dipoles, chaotic nonreversing dipoles, and chaotic reversing dipoles. The time average dipole strength and dipolarity of the magnetic field decrease, whereas the dipole variability, average dipole tilt angle, and frequency of polarity reversals increase with Rayleigh number. Chaotic gravitational dynamos have large-amplitude dipole secular variation with maximum power at frequencies corresponding to a few cycles per million years on Earth. Their external magnetic field structure, dipole statistics, low-frequency power spectra, and polarity reversal frequency are comparable to the geomagnetic field. The magnetic variability is driven by the Lorentz force and is characterized by an inverse correlation between dynamo magnetic and kinetic energy fluctuations. A constant energy dissipation theory accounts for this inverse energy correlation, which is shown to produce conditions favorable for dipole drift, polarity reversals, and excursions.

Gravitational dynamos and the low-frequency geomagnetic secular variation

PubMed Central

Olson, P.

2007-01-01

Self-sustaining numerical dynamos are used to infer the sources of low-frequency secular variation of the geomagnetic field. Gravitational dynamo models powered by compositional convection in an electrically conducting, rotating fluid shell exhibit several regimes of magnetic field behavior with an increasing Rayleigh number of the convection, including nearly steady dipoles, chaotic nonreversing dipoles, and chaotic reversing dipoles. The time average dipole strength and dipolarity of the magnetic field decrease, whereas the dipole variability, average dipole tilt angle, and frequency of polarity reversals increase with Rayleigh number. Chaotic gravitational dynamos have large-amplitude dipole secular variation with maximum power at frequencies corresponding to a few cycles per million years on Earth. Their external magnetic field structure, dipole statistics, low-frequency power spectra, and polarity reversal frequency are comparable to the geomagnetic field. The magnetic variability is driven by the Lorentz force and is characterized by an inverse correlation between dynamo magnetic and kinetic energy fluctuations. A constant energy dissipation theory accounts for this inverse energy correlation, which is shown to produce conditions favorable for dipole drift, polarity reversals, and excursions. PMID:18048345

Effect of Facemask Use on Respiratory Patterns of Women in Speech and Singing

ERIC Educational Resources Information Center

Collyer, Sally; Davis, Pamela J.

2006-01-01

Purpose: Research into respiratory behavior during singing and speech makes extensive use of standard respiratory and vented pneumotachograph facemasks. This study investigated whether the use of such facemasks would affect respiratory behavior in terms of lung volume (excursion, at initiation and at termination) or duration (of inspiration and of…

The Record of Geomagnetic Excursions from a ~150 m Sediment Core: Clear Lake, Northern California

NASA Astrophysics Data System (ADS)

Levin, E.; Byrne, R.; Looy, C. V.; Wahl, D.; Noren, A. J.; Verosub, K. L.

2015-12-01

We are studying the paleomagnetic properties of a new ~150 meter drill core from Clear Lake, CA. Step-wise demagnetization of the natural remanent magnetism (NRM) yields stable directions after 20 mT, implying that the sediments are reliable recorders of geomagnetic field behavior. Several intervals of low relative paleointensity (RPI) from the core appear to be correlated with known geomagnetic excursions. At about 46 m depth, and ~33 ka according to an age model based on radiocarbon dates obtained from pollen and the Olema ash bed, a low RPI zone seems to agree with the age and duration of the Mono Lake Excursion, previously identified between 32 and 35 ka. Slightly lower in the core, at about 50 m depth and ~40 ka, noticeably low RPI values seem to be coeval with the Laschamp excursion, which has been dated at ~41 ka. A volcanic ash near the bottom of the core (141 mblf) is near the same depth as an ash identified in 1988 by Andrei Sarna-Wojcicki and others as the Loleta ash bed in a previous Clear Lake core. If the basal ash in the new core is indeed the, Loleta ash bed, then the core may date back to about 270-300 ka. Depending on the age of the lowest ash, a sequence of low RPI intervals could correlate with the Blake (120 ka), Iceland Basin (188 ka), Jamaica/Pringle Falls (211 ka), and CR0 (260 ka) excursions. Correlation of the low RPI intervals to these geomagnetic excursions will help in the development of a higher resolution chronostratigraphy for the core, resolve a long-standing controversy about a possible hiatus in the Clear Lake record, and provide information about climatically-driven changes in sedimentation.

Burn Control Mechanisms in Tokamaks

NASA Astrophysics Data System (ADS)

Hill, M. A.; Stacey, W. M.

2015-11-01

Burn control and passive safety in accident scenarios will be an important design consideration in future tokamak reactors, in particular fusion-fission hybrid reactors, e.g. the Subcritical Advanced Burner Reactor. We are developing a burning plasma dynamics code to explore various aspects of burn control, with the intent to identify feedback mechanisms that would prevent power excursions. This code solves the coupled set of global density and temperature equations, using scaling relations from experimental fits. Predictions of densities and temperatures have been benchmarked against DIII-D data. We are examining several potential feedback mechanisms to limit power excursions: i) ion-orbit loss, ii) thermal instability density limits, iii) MHD instability limits, iv) the degradation of alpha-particle confinement, v) modifications to the radial current profile, vi) ``divertor choking'' and vii) Type 1 ELMs. Work supported by the US DOE under DE-FG02-00ER54538, DE-FC02-04ER54698.

A Scientific Excursion: Volcanoes.

ERIC Educational Resources Information Center

Olds, Henry, Jr.

1983-01-01

Reviews an educationally valuable and reasonably well-designed simulation of volcanic activity in an imaginary land. VOLCANOES creates an excellent context for learning information about volcanoes and for developing skills and practicing methods needed to study behavior of volcanoes. (Author/JN)

THE EFFECTS OF TRANSIENTS ON PHOTOSPHERIC AND CHROMOSPHERIC POWER DISTRIBUTIONS

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

Samanta, T.; Banerjee, D.; Pant, V.

2016-09-01

We have observed a quiet-Sun region with the Swedish 1 m Solar Telescope equipped with the CRISP Imaging SpectroPolarimeter. High-resolution, high-cadence, H α line scanning images were taken to observe different layers of the solar atmosphere from the photosphere to upper chromosphere. We study the distribution of power in different period bands at different heights. Power maps of the upper photosphere and the lower chromosphere show suppressed power surrounding the magnetic-network elements, known as “magnetic shadows.” These also show enhanced power close to the photosphere, traditionally referred to as “power halos.” The interaction between acoustic waves and inclined magnetic fieldsmore » is generally believed to be responsible for these two effects. In this study we explore whether small-scale transients can influence the distribution of power at different heights. We show that the presence of transients, like mottles, Rapid Blueshifted Excursions (RBEs), and Rapid Redshifted Excursions (RREs), can strongly influence the power maps. The short and finite lifetime of these events strongly affects all power maps, potentially influencing the observed power distribution. We show that Doppler-shifted transients like RBEs and RREs that occur ubiquitously can have a dominant effect on the formation of the power halos in the quiet Sun. For magnetic shadows, transients like mottles do not seem to have a significant effect on the power suppression around 3 minutes, and wave interaction may play a key role here. Our high-cadence observations reveal that flows, waves, and shocks manifest in the presence of magnetic fields to form a nonlinear magnetohydrodynamic system.« less

Determining the Accuracy of Paleomagnetic Remanence and High-Resolution Chronostratigraphy for Sedimentary Rocks using Rock Magnetics

NASA Astrophysics Data System (ADS)

Kodama, K. P.

2017-12-01

The talk will consider two broad topics in rock magnetism and paleomagnetism: the accuracy of paleomagnetic remanence and the use of rock magnetics to measure geologic time in sedimentary sequences. The accuracy of the inclination recorded by sedimentary rocks is crucial to paleogeographic reconstructions. Laboratory compaction experiments show that inclination shallows on the order of 10˚-15˚. Corrections to the inclination can be made using the effects of compaction on the directional distribution of secular variation recorded by sediments or the anisotropy of the magnetic grains carrying the ancient remanence. A summary of all the compaction correction studies as of 2012 shows that 85% of sedimentary rocks studied have enjoyed some amount of inclination shallowing. Future work should also consider the effect of grain-scale strain on paleomagnetic remanence. High resolution chronostratigraphy can be assigned to a sedimentary sequence using rock magnetics to detect astronomically-forced climate cycles. The power of the technique is relatively quick, non-destructive measurements, the objective identification of the cycles compared to facies interpretations, and the sensitivity of rock magnetics to subtle changes in sedimentary source. An example of this technique comes from using rock magnetics to identify astronomically-forced climate cycles in three globally distributed occurrences of the Shuram carbon isotope excursion. The Shuram excursion may record the oxidation of the world ocean in the Ediacaran, just before the Cambrian explosion of metazoans. Using rock magnetic cyclostratigraphy, the excursion is shown to have the same duration (8-9 Myr) in southern California, south China and south Australia. Magnetostratigraphy of the rocks carrying the excursion in California and Australia shows a reversed to normal geomagnetic field polarity transition at the excursion's nadir, thus supporting the synchroneity of the excursion globally. Both results point to a primary depositional origin for the excursion, and strengthens the argument for oxidation of the world ocean in the Ediacaran. Future work must learn how global climate is encoded by rock magnetics, but our work to date suggests that variations in continental run-off are detected by rock magnetics.

Design of high-capacity fiber-optic transport systems

NASA Astrophysics Data System (ADS)

Liao, Zhi Ming

2001-08-01

We study the design of fiber-optic transport systems and the behavior of fiber amplifiers/lasers with the aim of achieving higher capacities with larger amplifier spacing. Solitons are natural candidates for transmitting short pulses for high-capacity fiber-optic networks because of its innate ability to use two of fiber's main defects, fiber dispersion and fiber nonlinearity to balance each other. In order for solitons to retain its dynamic nature, amplifiers must be placed periodically to restore powers to compensate for fiber loss. Variational analysis is used to study the long-term stability of a periodical- amplifier system. A new regime of operation is identified which allows the use of a much longer amplifier spacing. If optical fibers are the blood vessels of an optical communication system, then the optical amplifier based on erbium-doped fiber is the heart. Optical communication systems can avoid the use of costly electrical regenerators to maintain system performance by being able to optically amplify the weakened signals. The length of amplifier spacing is largely determined by the gain excursion experienced by the solitons. We propose, model, and demonstrate a distributed erbium-doped fiber amplifier which can drastically reduce the amount of gain excursion experienced by the solitons, therefore allowing a much longer amplifier spacing and superior stability. Dispersion management techniques have become extremely valuable tools in the design of fiber-optic communication systems. We have studied in depth the advantage of different arnplification schemes (lumped and distributed) for various dispersion compensation techniques. We measure the system performance through the Q factor to evaluate the added advantage of effective noise figure and smaller gain excursion. An erbium-doped fiber laser has been constructed and characterized in an effort to develop a test bed to study transmission systems. The presence of mode-partition noise in an erbium-doped fiber laser was experimentally demonstrated. A numerical model has been developed using the Langevin rate equations and its predictions are in qualitative agreement with experimental data.

On the suitability of fibre optical parametric amplifiers for use in all-optical agile photonic networks

NASA Astrophysics Data System (ADS)

Gryspolakis, Nikolaos

The objective of this thesis is to investigate the suitability of fibre optical parametric amplifiers (FOPAs) for use in multi-channel, dynamic networks. First, we investigate their quasi-static behaviour in such an environment. We study the behaviour of a FOPA under realistic conditions and we examine the impact on the gain spectrum of channel addition for several different operating conditions and regimes. In particular, we examine the impact of surviving channel(s) position, input power and channel spacing. We see how these parameters affect the gain tilt as well as its dynamic characteristics, namely the generation of under or over-shoots at the transition point, possible dependence of rise and fall times on any of the aforementioned parameters and how the gain excursions depend on those parameters. For these studies we assume continuous wave operation for all signals. We observe that the gain spectrum changes are a function of the position and the spacing of the channels. We also find that the gain excursion can reach several dBs (up to 5 dB) in the case of channel add/drop and are heavily dependent on the position of the surviving channels. The channels located in the middle of the transmission band are more prone to channel add/drop-induced gain changes. Moreover, we investigate for the first time the FOPA dynamic behaviour in a packet switching scenario. This part of the study assumes that all but one channels normally vary in a packet-switched fashion. The remaining channel (probe channel) is expected to undergo gain variations due to the perturbation of the system experienced by the other channels. Furthermore, we consider several different scenarios for which the channels spacing, per channel input power (PCIP), variance of the power fluctuation and position of the probe channel will change. We find that when the FOPA operates near saturation the target gain is not achieved more than 50% of the time while the peak-to-peak gain excursions can exceed 1 dB. Next, we introduce modulated channels to the amplifier in order to compare their effect on the Bit Error Rate (BER) performance. We consider the impact on FOPAs when employing different modulation formats, such as RZ, NRZ and RZ-DPSK. Carefully selected modulation formats can improve BER performance and reduce the effects of cross-phase modulation, four wave mixing (FWM) products generation or dispersion (non-linear and linear inter-channel interference). Especially for the case of FOPAs, because of the ultra-fast interaction times of the FWM phenomenon, cross gain modulation can be a great deterrent for using FOPAs. We use RZ-DPSK in order to suppress the WDM signal crosstalk. Only by using RZ-DPSK, we obtain an improved receiver sensitivity of 5 dB when operating at 40 Gb/s. Finally, we investigate ways to mitigate such effects as the ones described above (gain excursions, gain tilt, etc.). We demonstrate that by using a ring configuration with optical feedback for the first time in FOPAs, we can achieve all-optical gain clamping (AOGC), mitigating gain excursions and attaining gain, independent of channel input power for a large range of PCIP. For example, with the use of AOGC, we reduce the add/drop-induced gain excursions from 4 dB to 0.6 dB. Also, by the combined use of AOGC and RZ-DPSK, we mitigate most of the aforementioned hindrances described above.

Dating the Laschamp Excursion: Why Speleothems are Valuable Tools for Constraining the Timing and Duration of Short-Lived Geomagnetic Events

NASA Astrophysics Data System (ADS)

Lascu, I.; Feinberg, J. M.; Dorale, J. A.; Cheng, H.; Edwards, R. L.

2015-12-01

Short-lived geomagnetic events are reflections of geodynamo behavior at small length scales. A rigorous documentation of the anatomy, timing, duration, and frequency of centennial-to-millennial scale geomagnetic events can be invaluable for theoretical and numerical geodynamo models, and for the understanding the finer dynamics of the Earth's core. A critical ingredient for characterizing such geomagnetic instabilities are tightly constrained age models that enable high-resolution magnetostratigraphies. Here we focus on a North American speleothem geomagnetic record of the Laschamp excursion, which was the first geomagnetic excursion recognized and described in the paleomagnetic record, and remains the most studied event of its kind. The geological significance of the Laschamp lies chiefly in the fact that it constitutes a global time-synchronous geochronological marker. The Laschamp excursion occurred around the time of the demise of Homo neanderthalensis, in conjunction with high-amplitude, rapid climatic oscillations leading into the Last Glacial Maximum, and precedes a major supervolcano eruption in the Mediterranean. Thus, the precise determination of the timing and duration of the Laschamp would help in elucidating major scientific questions situated at the intersection of geology, paleoclimatology, and anthropology. Here we present a geomagnetic record from a stalagmite collected in Crevice Cave, Missouri, which we have dated using a combination of high-precision 230Th ages and annual layer counting using confocal microscopy. We have found a maximum duration for the Laschamp that spans the interval 42,250-39,700 years BP, and an age of 41,100 ± 350 years BP for the height of the excursion. During this period relative paleointensity decreased by an order of magnitude and the virtual geomagnetic pole was located at southerly latitudes. Our chronology provides the first robust bracketing for the Laschamp excursion, and improves on previous age determinations based on 40Ar/39Ar dating of lava flows, and orbitally-tuned sedimentary and ice-core records.

Micro-foundation using percolation theory of the finite time singular behavior of the crash hazard rate in a class of rational expectation bubbles

NASA Astrophysics Data System (ADS)

Seyrich, Maximilian; Sornette, Didier

2016-04-01

We present a plausible micro-founded model for the previously postulated power law finite time singular form of the crash hazard rate in the Johansen-Ledoit-Sornette (JLS) model of rational expectation bubbles. The model is based on a percolation picture of the network of traders and the concept that clusters of connected traders share the same opinion. The key ingredient is the notion that a shift of position from buyer to seller of a sufficiently large group of traders can trigger a crash. This provides a formula to estimate the crash hazard rate by summation over percolation clusters above a minimum size of a power sa (with a>1) of the cluster sizes s, similarly to a generalized percolation susceptibility. The power sa of cluster sizes emerges from the super-linear dependence of group activity as a function of group size, previously documented in the literature. The crash hazard rate exhibits explosive finite time singular behaviors when the control parameter (fraction of occupied sites, or density of traders in the network) approaches the percolation threshold pc. Realistic dynamics are generated by modeling the density of traders on the percolation network by an Ornstein-Uhlenbeck process, whose memory controls the spontaneous excursion of the control parameter close to the critical region of bubble formation. Our numerical simulations recover the main stylized properties of the JLS model with intermittent explosive super-exponential bubbles interrupted by crashes.

Quaternary magnetic excursions recorded in marine sediments.

NASA Astrophysics Data System (ADS)

Channell, J. E. T.

2017-12-01

This year is the golden (50th) anniversary of the first documentation of a magnetic excursion, the Laschamp excursion in volcanics from the Chaine des Puys (Bonhommet and Babkine, 1967). The first recording of an excursion in sediments was from the Blake Outer Ridge (Smith and Foster, 1969). Magnetic excursions are directional aberrations of the geomagnetic field apparently involving short-lived reversal of the main dipole field. They have durations of a few kyrs, and are therefore rarely recorded in sediments with mean sedimentation rates <10 cm/kyr. Certain Brunhes-aged excursions are now well documented having been recorded in both marine sediments and in lavas (Laschamp excursion, 41 ka). Other excursions have not been adequately recorded in lavas, but have been widely recorded in marine and lake sediments (Iceland Basin excursion, 190 ka). The recording of excursions is fortuitous both in lava sequences and in marine sediments due to their millennial/centennial-scale duration, however, the global recording of the Laschamp and Iceland Basin excursions imply that excursions involve the main dipole field, are recorded synchronously over the globe, and are therefore important in stratigraphic correlation. The marine sediment record includes magnetic excursions at 26 ka (Rockall), 32 ka (Mono Lake), 41 ka (Laschamp), 115 ka (Blake), 190 ka (Iceland Basin), 238 ka (Pringle Falls?), 286 ka (Portuguese Orphan), 495 ka (Bermuda), 540 ka (Big Lost), 590 ka (La Palma), and 670 ka (Osaka Bay), implying at least 11 excursions in the Brunhes Chron. For the Matuyama Chron, excursions have been recorded in marine sediments at 868 ka (Kamikatsura?), 932 ka (Santa Rosa), 1051 ka (Intra-Jaramillo), 1115 ka (Punaruu), 1255 ka (Bjorn), 1476 ka (Gardar), 1580 ka (Gilsa), and 2737 ka (Porcupine). Excursions coincide with minima in relative paleointensity (RPI) records. Ages are from correlation of excursion records to oxygen isotope records in the same cores, and ice-volume calibration of the oxygen isotope template. The marine sediment record of excursions, combined with independent documentation of excursions in lavas with Ar/Ar age control, is progressively strengthening our knowledge of the excursion inventory in the Quaternary, and enhancing the importance of excursions and RPI in Quaternary stratigraphy.

Considerations in development and implementation of elasto-viscoplastic constitutive model for high temperature applications

NASA Technical Reports Server (NTRS)

Riff, Richard

1988-01-01

The prediction of inelastic behavior of metallic materials at elevated temperatures has increased in importance in recent years. The operating conditions within the hot section of a rocket motor or a modern gas turbine engine present an extremely harsh thermomechanical environment. Large thermal transients are induced each time the engine is started or shut down. Additional thermal transients from an elevated ambient occur whenever the engine power level is adjusted to meet flight requirements. The structural elements employed in such hot sections, as well as any engine components located therein, must be capable of withstanding such extreme conditions. Failure of a component would, due to the critical nature of the hot section, lead to an immediate and catastrophic loss in power. Consequently, assuring satisfactory long term performance for such components is a major concern. Nonisothermal loading of structures often causes excursion of stress well into the inelastic range. Moreover, the influence of geometry changes on the response is also significant in most cases. Therefore, both material and geometric nonlinear effects are considered.

Constraints on Early Triassic carbon cycle dynamics from paired organic and inorganic carbon isotope records

NASA Astrophysics Data System (ADS)

Meyer, K. M.; Yu, M.; Lehrmann, D.; van de Schootbrugge, B.; Payne, J. L.

2013-01-01

Large δ13C excursions, anomalous carbonate precipitates, low diversity assemblages of small fossils, and evidence for marine euxinia in uppermost Permian and Lower Triassic strata bear more similarity to Neoproterozoic carbonates than to the remainders of the Permian and Triassic systems. Middle Triassic diversification of marine ecosystems coincided with the waning of anoxia and stabilization of the global carbon cycle, suggesting that environment-ecosystem linkages were important to biological recovery. However, the Earth system behavior responsible for these large δ13C excursions remains poorly constrained. Here we present a continuous Early Triassic δ13Corg record from south China and use it to test the extent to which Early Triassic excursions in δ13Ccarb record changes in the δ13C of marine dissolved inorganic carbon (DIC). Regression analysis demonstrates a significant positive correlation between δ13Corg and δ13Ccarb across multiple sections that span a paleoenvironmental gradient. Such a correlation is incompatible with diagenetic alteration because no likely mechanism will alter both δ13Corg and δ13Ccarb records in parallel and therefore strongly indicates a primary depositional origin. A simple explanation for this correlation is that a substantial portion of the preserved Corg was derived from the contemporaneous DIC pool, implying that the observed excursions reflect variation in the δ13C of the exogenic carbon reservoir (ocean, atmosphere, biomass). These findings support existing evidence that large δ13C excursions are primary and therefore strengthen the case that large-scale changes to the carbon cycle were mechanistically linked to the low diversity and small size of Early Triassic fossils. Associated sedimentary and biogeochemical phenomena further suggest that similar associations in Neoproterozoic and Cambrian strata may reflect the same underlying controls.

High-resolution record of the Laschamp geomagnetic excursion at the Blake-Bahama Outer Ridge

NASA Astrophysics Data System (ADS)

Bourne, Mark D.; Mac Niocaill, Conall; Thomas, Alex L.; Henderson, Gideon M.

2013-12-01

Geomagnetic excursions are brief deviations of the geomagnetic field from behaviour expected during `normal secular' variation. The Laschamp excursion at ˜41 ka was one such deviation. Previously published records suggest rapid changes in field direction and a concurrent substantial decrease in field intensity associated with this excursion. Accurate dating of excursions, and determination of their durations from multiple locations, is vital to our understanding of global field behaviour during these deviations. We present here high-resolution palaeomagnetic records of the Laschamp excursion obtained from two Ocean Drilling Program (ODP) Sites, 1061 and 1062 on the Blake-Bahama Outer Ridge (ODP Leg 172). High sedimentation rates (˜30-40 cm kyr-1) at these locations allow determination of transitional field behaviour during the excursion. Palaeomagnetic measurements of discrete samples from four cores reveal a single excursional feature, across an interval of 30 cm, associated with a broader palaeointensity low. We determine the age and duration of the Laschamp excursion using a stratigraphy linked to the δ18O record from the Greenland ice cores. This chronology dates the Laschamp excursion at the Blake Ridge to 41.3 ka. The excursion is characterized by rapid transitions (less than 200 yr) between stable normal polarity and a partially reversed polarity state. The palaeointensity record is in good agreement between the two sites, revealing two prominent minima. The first minimum is associated with the Laschamp excursion at 41 ka and the second corresponds to the Mono Lake excursion at ˜35.5 ka. We determine that the directional excursion during the Laschamp at this location was no longer than ˜400 yr, occurring within a palaeointensity minimum that lasted 2000 yr. The Laschamp excursion at this location is much shorter in duration than the Blake and Iceland Basin excursions.

Speed And Power Control Of An Engine By Modulation Of The Load Torque

DOEpatents

Ziph, Benjamin; Strodtman, Scott; Rose, Thomas K

1999-01-26

A system and method of speed and power control for an engine in which speed and power of the engine is controlled by modulation of the load torque. The load torque is manipulated in order to cause engine speed, and hence power to be changed. To accomplish such control, the load torque undergoes a temporary excursion in the opposite direction of the desired speed and power change. The engine and the driven equipment will accelerate or decelerate accordingly as the load torque is decreased or increased, relative to the essentially fixed or constant engine torque. As the engine accelerates or decelerates, its power increases or decreases in proportion.

Steady-state phase error for a phase-locked loop subjected to periodic Doppler inputs

NASA Technical Reports Server (NTRS)

Chen, C.-C.; Win, M. Z.

1991-01-01

The performance of a carrier phase locked loop (PLL) driven by a periodic Doppler input is studied. By expanding the Doppler input into a Fourier series and applying the linearized PLL approximations, it is easy to show that, for periodic frequency disturbances, the resulting steady state phase error is also periodic. Compared to the method of expanding frequency excursion into a power series, the Fourier expansion method can be used to predict the maximum phase error excursion for a periodic Doppler input. For systems with a large Doppler rate fluctuation, such as an optical transponder aboard an Earth orbiting spacecraft, the method can be applied to test whether a lower order tracking loop can provide satisfactory tracking and thereby save the effect of a higher order loop design.

Intermittent many-body dynamics at equilibrium

NASA Astrophysics Data System (ADS)

Danieli, C.; Campbell, D. K.; Flach, S.

2017-06-01

The equilibrium value of an observable defines a manifold in the phase space of an ergodic and equipartitioned many-body system. A typical trajectory pierces that manifold infinitely often as time goes to infinity. We use these piercings to measure both the relaxation time of the lowest frequency eigenmode of the Fermi-Pasta-Ulam chain, as well as the fluctuations of the subsequent dynamics in equilibrium. The dynamics in equilibrium is characterized by a power-law distribution of excursion times far off equilibrium, with diverging variance. Long excursions arise from sticky dynamics close to q -breathers localized in normal mode space. Measuring the exponent allows one to predict the transition into nonergodic dynamics. We generalize our method to Klein-Gordon lattices where the sticky dynamics is due to discrete breathers localized in real space.

The Role of the Intellectual--An Excursion into Self-Criticism.

ERIC Educational Resources Information Center

Galtung, Johan

2002-01-01

Distinguishes two roles of the intellectual, one in search of truth and the other in search of power. Sees the latter as closely related to the emergence of nation states and centralized capitalism and as problematic when it results in a small elite expropriating the challenges that should belong to others. (EV)

75 FR 26841 - Petition for Waiver of Compliance

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-12

... definition of ``antiquated'' is being built prior to the end of World War II, even though this equipment is... equipment in steam and diesel locomotive powered excursion service on the entire trackage of the Great Lakes... accordance with part 211 of title 49 Code of Federal Regulations (CFR), notice is hereby given that the...

Rain, Mud, Bikes and the Power of Relationships

ERIC Educational Resources Information Center

Willis, Judy

2005-01-01

In this article, the author describes her experiences on an annual teacher-student bike excursion at Santa Barbara Middle School in California. The trip, while plagued with rain, allowed her to develop closer relationships with her students that extended into the classroom. These continuing relationships have led to the establishment of greater…

Edge Mechanisms for Power Excursion Control in Burning Plasmas

NASA Astrophysics Data System (ADS)

Hill, M. D.; Stacey, W. M.

2017-10-01

ITER must have active and preferably also passive control mechanisms that will limit inadvertent plasma power excursions which could trigger runaway fusion heating. We are identifying and investigating the potential of ion-orbit loss, impurity seeding, and various divertor ``choking'' phenomena to control or limit sudden increases in plasma density or temperature by reducing energy confinement, increasing radiation loss, etc., with the idea that such mechanisms could be tested on DIII-D and other existing tokamaks. We are assembling an edge-divertor code (GTEDGE-2) with a neutral transport model and a burn dynamics code, for this purpose. One potential control mechanism is the enhanced ion orbit loss from the thermalized ion distribution that would result from heating of the thermalized plasma ion distribution. Another possibility is impurity seeding with ions whose emissivity would increase sharply if the edge temperature increased. Enhanced radiative losses should also reduce the thermal energy flux across the separatrix, perhaps dropping the plasma into the poorer L-mode confinement regime. We will present some initial calculations to quantify these ideas. Work supported by US DOE under DE-FC02-04ER54698.

Differences in Pedaling Technique in Cycling: A Cluster Analysis.

PubMed

Lanferdini, Fábio J; Bini, Rodrigo R; Figueiredo, Pedro; Diefenthaeler, Fernando; Mota, Carlos B; Arndt, Anton; Vaz, Marco A

2016-10-01

To employ cluster analysis to assess if cyclists would opt for different strategies in terms of neuromuscular patterns when pedaling at the power output of their second ventilatory threshold (PO VT2 ) compared with cycling at their maximal power output (PO MAX ). Twenty athletes performed an incremental cycling test to determine their power output (PO MAX and PO VT2 ; first session), and pedal forces, muscle activation, muscle-tendon unit length, and vastus lateralis architecture (fascicle length, pennation angle, and muscle thickness) were recorded (second session) in PO MAX and PO VT2 . Athletes were assigned to 2 clusters based on the behavior of outcome variables at PO VT2 and PO MAX using cluster analysis. Clusters 1 (n = 14) and 2 (n = 6) showed similar power output and oxygen uptake. Cluster 1 presented larger increases in pedal force and knee power than cluster 2, without differences for the index of effectiveness. Cluster 1 presented less variation in knee angle, muscle-tendon unit length, pennation angle, and tendon length than cluster 2. However, clusters 1 and 2 showed similar muscle thickness, fascicle length, and muscle activation. When cycling at PO VT2 vs PO MAX , cyclists could opt for keeping a constant knee power and pedal-force production, associated with an increase in tendon excursion and a constant fascicle length. Increases in power output lead to greater variations in knee angle, muscle-tendon unit length, tendon length, and pennation angle of vastus lateralis for a similar knee-extensor activation and smaller pedal-force changes in cyclists from cluster 2 than in cluster 1.

Transplanckian censorship and global cosmic strings

NASA Astrophysics Data System (ADS)

Dolan, Matthew J.; Draper, Patrick; Kozaczuk, Jonathan; Patel, Hiren

2017-04-01

Large field excursions are required in a number of axion models of inflation. These models also possess global cosmic strings, around which the axion follows a path mirroring the inflationary trajectory. Cosmic strings are thus an interesting theoretical laboratory for the study of transplanckian field excursions. We describe connections be-tween various effective field theory models of axion monodromy and study the classical spacetimes around their supercritical cosmic strings. For small decay constants f < M p and large winding numbers n > M p /f , the EFT is under control and the string cores undergo topological inflation, which may be either of exponential or power-law type. We show that the exterior spacetime is nonsingular and equivalent to a decompactifying cigar geometry, with the radion rolling in a potential generated by axion flux. Signals are able to circumnavigate infinite straight strings in finite but exponentially long time, t ˜ e Δ a/ M p . For finite loops of supercritical string in asymptotically flat space, we argue that if topological inflation occurs, then topological censorship implies transplanckian censorship, or that external observers are forbidden from threading the loop and observing the full excursion of the axion.

Addendum to NuMI shielding assessment

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

Vaziri, Kamran; /Fermilab

2007-10-01

The original safety assessment and the Safety Envelope for the NuMI beam line corresponds to 400 kW of beam power. The Main Injector is currently capable of and approved for producing 500 kW of beam power2. However, operation of the NuMI beam line at 400 kW of power brings up the possibility of an occasional excursion above 400 kW due to better than usual tuning in one of the machines upstream of the NuMI beam line. An excursion above the DOE approved Safety Envelope will constitute a safety violation. The purpose of this addendum is to evaluate the radiological issuesmore » and modifications required to operate the NuMI beam line at 500 kW. This upgrade will allow 400 kW operations with a reasonable safety margin. Configuration of the NuMI beam line, boundaries, safety system and the methodologies used for the calculations are as described in the original NuMI SAD. While most of the calculations presented in the original shielding assessment were based on Monte Carlo simulations, which were based on the design geometries, most of the results presented in this addendum are based on the measurements conducted by the AD ES&H radiation safety group.« less

Preliminary paleomagnetic results from the Coyote Creek Outdoor Classroom drill hole, Santa Clara Valley, California

USGS Publications Warehouse

Mankinen, Edward A.; Wentworth, Carl M.

2003-01-01

Paleomagnetic samples were obtained from cores taken during the drilling of a research well along Coyote Creek in San Jose, California, in order to use the geomagnetic field behavior recorded in those samples to provide age constraints for the sediment encountered. The well reached a depth of 308 meters and material apparently was deposited largely (entirely?) during the Brunhes Normal Polarity Chron, which lasted from 780 ka to the present time. Three episodes of anomalous magnetic inclinations were recorded in parts of the sedimentary sequence; the uppermost two we correlate to the Mono Lake (~30 ka) geomagnetic excursion and 6 cm lower, tentatively to the Laschamp (~45 ka) excursion. The lowermost anomalous interval occurs at 305 m and consists of less than 10 cm of fully reversed inclinations underlain by 1.5 m of normal polarity sediment. This lower anomalous interval may represent either the Big Lost excursion (~565 ka) or the polarity transition at the end of the Matuyama Reversed Polarity Chron (780 ka). The average rates of deposition for the Pleistocene section in this well, based on these two alternatives, are approximately 52 or 37 cm/kyr, respectively.

Preliminary Earth System Modeling (cGENIE) of Paired Organic and Inorganic Carbon Isotope Records to Investigate Carbon Cycle Behavior During the Triassic-Jurassic Transition

NASA Astrophysics Data System (ADS)

Yager, J. A.; Stellmann, J. L.; West, A. J.; Corsetti, F. A.; Berelson, W.; Bottjer, D. J.; Rosas, S.

2016-12-01

The stable C isotope composition of marine carbonate and organic C yields information regarding major changes in global carbon cycling over geologic time. Excursions from baseline C isotope compositions during the Late Triassic and early Jurassic coincide with the end-Triassic mass extinction. Much remains to be understood about the global extent of these excursions, and about their causes. Here, we use observations from a record from Northern Peru (Levanto) to generate hypotheses concerning C cycle changes, focusing on comparison to other sections spanning the Triassic-Jurassic boundary. Our observations include a decoupling between organic and inorganic C isotopes in some records, broad similarities in the pattern of excursions between sections, and a potential offset between the major ocean basins (Tethys and Panthalassa) in both inorganic and organic C isotope records. We are currently adapting a spatially resolved Earth System Model (cGENIE) for this time period with the goal of using this model to explore possible mechanistic causes of these observations, aiming to tie the C isotope records to changes in global carbon cycle dynamics at the time.

Practices and Methods for Actualization of the Scientific Information in Art Excursions (Excursions and Cultural Heritage in the Contemporary World)

ERIC Educational Resources Information Center

Portnova, Tatiana V.

2016-01-01

The paper deals with various practices and methods for actualization of the scientific information in art excursions. The modern society is characterized by commitment to information richness. The range of cultural and historical materials used as the basis for art excursions is really immense. However if to consider the number of excursions with…

Enhanced optical gain clamping for upstream packet based traffic on hybrid WDM/TDM-PON using fiber Bragg grating

NASA Astrophysics Data System (ADS)

Neto, B.; Klingler, A.; Reis, C.; Dionísio, R. P.; Nogueira, R. N.; Teixeira, A. L. J.; André, P. S.

2011-03-01

In this paper, we propose a method to mitigate the temporal power transients arising from Erbium doped fiber amplifiers (EDFAs) on packeted/bursty scenario. The technique, applicable on hybrid WDM/TDM-PON for extended reach, is based on a low power clamping provided by a distributed feedback (DFB) laser and a fiber Bragg grating (FBG). An improvement in the data signal Q factor was achieved keeping the clamping control signal with a low power, accompanied by a maximum reduction in the gain excursion of 1.12 dB.

Qualification of CASMO5 / SIMULATE-3K against the SPERT-III E-core cold start-up experiments

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

Grandi, G.; Moberg, L.

SIMULATE-3K is a three-dimensional kinetic code applicable to LWR Reactivity Initiated Accidents. S3K has been used to calculate several international recognized benchmarks. However, the feedback models in the benchmark exercises are different from the feedback models that SIMULATE-3K uses for LWR reactors. For this reason, it is worth comparing the SIMULATE-3K capabilities for Reactivity Initiated Accidents against kinetic experiments. The Special Power Excursion Reactor Test III was a pressurized-water, nuclear-research facility constructed to analyze the reactor kinetic behavior under initial conditions similar to those of commercial LWRs. The SPERT III E-core resembles a PWR in terms of fuel type, moderator,more » coolant flow rate, and system pressure. The initial test conditions (power, core flow, system pressure, core inlet temperature) are representative of cold start-up, hot start-up, hot standby, and hot full power. The qualification of S3K against the SPERT III E-core measurements is an ongoing work at Studsvik. In this paper, the results for the 30 cold start-up tests are presented. The results show good agreement with the experiments for the reactivity initiated accident main parameters: peak power, energy release and compensated reactivity. Predicted and measured peak powers differ at most by 13%. Measured and predicted reactivity compensations at the time of the peak power differ less than 0.01 $. Predicted and measured energy release differ at most by 13%. All differences are within the experimental uncertainty. (authors)« less

An activity index for geomagnetic paleosecular variation, excursions, and reversals

NASA Astrophysics Data System (ADS)

Panovska, S.; Constable, C. G.

2017-04-01

Magnetic indices provide quantitative measures of space weather phenomena that are widely used by researchers in geomagnetism. We introduce an index focused on the internally generated field that can be used to evaluate long term variations or climatology of modern and paleomagnetic secular variation, including geomagnetic excursions, polarity reversals, and changes in reversal rate. The paleosecular variation index, Pi, represents instantaneous or average deviation from a geocentric axial dipole field using normalized ratios of virtual geomagnetic pole colatitude and virtual dipole moment. The activity level of the index, σPi, provides a measure of field stability through the temporal standard deviation of Pi. Pi can be calculated on a global grid from geomagnetic field models to reveal large scale geographic variations in field structure. It can be determined for individual time series, or averaged at local, regional, and global scales to detect long term changes in geomagnetic activity, identify excursions, and transitional field behavior. For recent field models, Pi ranges from less than 0.05 to 0.30. Conventional definitions for geomagnetic excursions are characterized by Pi exceeding 0.5. Strong field intensities are associated with low Pi unless they are accompanied by large deviations from axial dipole field directions. σPi provides a measure of geomagnetic stability that is modulated by the level of PSV or frequency of excursional activity and reversal rate. We demonstrate uses of Pi for paleomagnetic observations and field models and show how it could be used to assess whether numerical simulations of the geodynamo exhibit Earth-like properties.

Analysis of the SL-1 Accident Using RELAPS5-3D

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

Francisco, A.D. and Tomlinson, E. T.

2007-11-08

On January 3, 1961, at the National Reactor Testing Station, in Idaho Falls, Idaho, the Stationary Low Power Reactor No. 1 (SL-1) experienced a major nuclear excursion, killing three people, and destroying the reactor core. The SL-1 reactor, a 3 MW{sub t} boiling water reactor, was shut down and undergoing routine maintenance work at the time. This paper presents an analysis of the SL-1 reactor excursion using the RELAP5-3D thermal-hydraulic and nuclear analysis code, with the intent of simulating the accident from the point of reactivity insertion to destruction and vaporization of the fuel. Results are presented, along with amore » discussion of sensitivity to some reactor and transient parameters (many of the details are only known with a high level of uncertainty).« less

Scalar excursions in large-eddy simulations

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

Matheou, Georgios; Dimotakis, Paul E.

Here, the range of values of scalar fields in turbulent flows is bounded by their boundary values, for passive scalars, and by a combination of boundary values, reaction rates, phase changes, etc., for active scalars. The current investigation focuses on the local conservation of passive scalar concentration fields and the ability of the large-eddy simulation (LES) method to observe the boundedness of passive scalar concentrations. In practice, as a result of numerical artifacts, this fundamental constraint is often violated with scalars exhibiting unphysical excursions. The present study characterizes passive-scalar excursions in LES of a shear flow and examines methods formore » diagnosis and assesment of the problem. The analysis of scalar-excursion statistics provides support of the main hypothesis of the current study that unphysical scalar excursions in LES result from dispersive errors of the convection-term discretization where the subgrid-scale model (SGS) provides insufficient dissipation to produce a sufficiently smooth scalar field. In the LES runs three parameters are varied: the discretization of the convection terms, the SGS model, and grid resolution. Unphysical scalar excursions decrease as the order of accuracy of non-dissipative schemes is increased, but the improvement rate decreases with increasing order of accuracy. Two SGS models are examined, the stretched-vortex and a constant-coefficient Smagorinsky. Scalar excursions strongly depend on the SGS model. The excursions are significantly reduced when the characteristic SGS scale is set to double the grid spacing in runs with the stretched-vortex model. The maximum excursion and volume fraction of excursions outside boundary values show opposite trends with respect to resolution. The maximum unphysical excursions increase as resolution increases, whereas the volume fraction decreases. The reason for the increase in the maximum excursion is statistical and traceable to the number of grid points (sample size) which increases with resolution. In contrast, the volume fraction of unphysical excursions decreases with resolution because the SGS models explored perform better at higher grid resolution.« less

Scalar excursions in large-eddy simulations

DOE PAGES

Matheou, Georgios; Dimotakis, Paul E.

2016-08-31

Here, the range of values of scalar fields in turbulent flows is bounded by their boundary values, for passive scalars, and by a combination of boundary values, reaction rates, phase changes, etc., for active scalars. The current investigation focuses on the local conservation of passive scalar concentration fields and the ability of the large-eddy simulation (LES) method to observe the boundedness of passive scalar concentrations. In practice, as a result of numerical artifacts, this fundamental constraint is often violated with scalars exhibiting unphysical excursions. The present study characterizes passive-scalar excursions in LES of a shear flow and examines methods formore » diagnosis and assesment of the problem. The analysis of scalar-excursion statistics provides support of the main hypothesis of the current study that unphysical scalar excursions in LES result from dispersive errors of the convection-term discretization where the subgrid-scale model (SGS) provides insufficient dissipation to produce a sufficiently smooth scalar field. In the LES runs three parameters are varied: the discretization of the convection terms, the SGS model, and grid resolution. Unphysical scalar excursions decrease as the order of accuracy of non-dissipative schemes is increased, but the improvement rate decreases with increasing order of accuracy. Two SGS models are examined, the stretched-vortex and a constant-coefficient Smagorinsky. Scalar excursions strongly depend on the SGS model. The excursions are significantly reduced when the characteristic SGS scale is set to double the grid spacing in runs with the stretched-vortex model. The maximum excursion and volume fraction of excursions outside boundary values show opposite trends with respect to resolution. The maximum unphysical excursions increase as resolution increases, whereas the volume fraction decreases. The reason for the increase in the maximum excursion is statistical and traceable to the number of grid points (sample size) which increases with resolution. In contrast, the volume fraction of unphysical excursions decreases with resolution because the SGS models explored perform better at higher grid resolution.« less

Interhemispheric difference of pallidal local field potential activity in cervical dystonia.

PubMed

Lee, Jung Ryun; Kiss, Zelma H T

2014-03-01

Cervical dystonia (CD) produces involuntary neck muscle contractions that result in abnormal and often asymmetrical postures of the head and neck. Basal ganglia oscillatory activity in the 3-12 Hz band correlating with involuntary muscle activity suggests a role in the pathophysiology of primary dystonia. Despite the asymmetrical postures seen with CD, no comparison of interhemispheric differences of pallidal local field potential (LFP) activity has been reported. The aim of this study was to examine the interhemispheric differences of LFP power in globus pallidus interna (GPi) in CD patients and compare these with their predominant head excursion identified as torticollis, laterocollis and retrocollis. LFPs were recorded from bilateral GPi in 11 patients with CD using microelectrodes during deep brain stimulation surgery. LFP power was measured in right and left GPi separately. The mean percentage of total GPi LFP power in 4-30 Hz frequency band on each brain side was determined and related to their predominant CD symptoms. Interhemispheric difference in the mean percentage of LFP power in 4-12 Hz and 13-30 Hz band frequencies was found in patients with torticollis and laterocollis regardless of excursion direction. However, patients with retrocollis did not show interhemispheric difference in LFP activity in any band frequency. Interhemispheric differences in synchronisation of pallidal LFP activity in 4-12 Hz and 13-30 Hz bands are related to the CD clinical condition, suggesting that these frequencies are important in the pathophysiology of dystonia.

Multipathway modulation of exercise and glucose stress effects upon GH secretion in healthy men.

PubMed

Veldhuis, Johannes D; Olson, Thomas P; Takahashi, Paul Y; Miles, John M; Joyner, Michael J; Yang, Rebecca J; Wigham, Jean

2015-09-01

Exercise evokes pulsatile GH release followed by autonegative feedback, whereas glucose suppresses GH release followed by rebound-like GH release (feedforward escape). Here we test the hypothesis that age, sex steroids, insulin, body composition and physical power jointly determine these dynamic GH responses. This was a prospectively randomized glucose-blinded study conducted in the Mayo Center for Advancing Translational Sciences in healthy men ages 19-77 years (N=23). Three conditions, fasting/rest/saline, fasting/exercise/saline and fasting/rest/iv glucose infusions, were used to drive GH dynamics during 10-min blood sampling for 6h. Linear correlation analysis was applied to relate peak/nadir GH dynamics to age, sex steroids, insulin, CT-estimated abdominal fat and physical power (work per unit time). Compared with the fasting/rest/saline (control) day, fasting/exercise/saline infusion evoked peak GH within 1h, followed by negative feedback 3-5h later. The dynamic GH excursion was strongly (R(2)=0.634) influenced by (i) insulin negatively (P=0.011), (ii) power positively (P=0.0008), and (iii) E2 positively (P=0.001). Dynamic glucose-modulated GH release was determined by insulin negatively (P=0.0039) and power positively (P=0.0034) (R(2)=0.454). Under rest/saline, power (P=0.031) and total abdominal fat (P=0.012) (R(2)=0.267) were the dominant correlates of GH excursions. In healthy men, dynamic GH perturbations induced by exercise and glucose are strongly related to physical power, insulin, estradiol, and body composition, thus suggesting a network of regulatory pathways. Copyright © 2015 Elsevier Inc. All rights reserved.

Cricket Behavior: Observing Insects to Learn about Science & Scientific Inquiry

ERIC Educational Resources Information Center

Rop, Charles J.

2008-01-01

Biology teachers know how important it is for them and for their students to engage first-hand with nature. Ideally, bringing students to fields, woodlands, and wetlands to observe, explore, and wonder is the best way to stimulate curiosity and practice scientific inquiry. However, for many reasons, field excursions are not always practical or…

The Effects of Terrain on a System of Systems

DTIC Science & Technology

2008-12-01

presented in this research may not have been exercised for all cases of interest. While every effort has been made, within the time available, to ensure...Prompting for Location to Save All Excursion Files...behavioral characteristics and capabilities of all the forces can be found in Appendix B. 1. Simulation Goal The scenarios developed are designed to

Mid-Brunhes magnetic excursions in marine isotope stages 9, 13, 14, and 15 (286, 495, 540, and 590 ka) at North Atlantic IODP Sites U1302/3, U1305, and U1306

NASA Astrophysics Data System (ADS)

Channell, J. E. T.

2017-02-01

Integrated Ocean Drilling Program (IODP) Site U1302/3 (Orphan Knoll, off Newfoundland) recorded magnetic excursions in marine isotope stages (MIS) 9a (at 286 ka) and 13a (at 495 ka). Sites U1306 and U1305 (Eirik Drift, off SE Greenland) record excursions in MIS 14a/b (at 540 ka) and 15b/c (at 590 ka). In the excursion intervals, magnetic measurements of continuous "u-channel" samples from multiple holes within site are augmented by measurements of cubic (8 cm3) discrete samples. The excursions lie in relative paleointensity (RPI) minima at each site and in RPI reference stacks, and correspond to dated intervals of 10Be overproduction in other deep-sea sediment records. Although observed at multiple holes at each site, and from u-channel and discrete samples, the excursions are not observed at all three sites, and often at only one of the three sites. Sporadic recording of these magnetic excursions, and excursions in general, is attributed to a combination of filtering by the process of acquisition of detrital remanent magnetization (DRM), postdepositional overprint of weak excursion magnetizations, the millennial or even centennial duration of directional excursions, and nonuniform sedimentation rates at these timescales in North Atlantic sediment drifts.

High-resolution palaeomagnetic records of the Laschamp geomagnetic excursion from the Blake Ridge

NASA Astrophysics Data System (ADS)

Mac Niocaill, C.; Bourne, M. D.; Thomas, A. L.; Henderson, G. M.

2013-05-01

Geomagnetic excursions are brief (1000s of years) deviations in geomagnetic field behaviour from that expected during 'normal secular' variation. The Laschamp excursion (~41 ka) was a global deviation in geomagnetic field behaviour. Previously published records suggest rapid changes in field direction and a concurrent substantial decrease in field intensity. Accurate dating of excursions and determinations of their durations from multiple locations is vital to our understanding to global field behaviour during these deviations. We present here high-resolution palaeomagnetic records of the Laschamp excursion obtained from two Ocean Drilling Program (ODP) Sites 1061 and 1062 on the Blake-Bahama Outer Ridge (ODP Leg 172) Relatively high sedimentation rates (~30-40 cm kyr-1) at these locations allow the determination of transitional field behaviour during the excursion. Despite their advantages, sedimentary records can be limited by the potential for unrecognized variations in sedimentation rates between widely spaced age-constrained boundaries. Rather than assuming a constant sedimentation rate between assigned age tie-points, we employ measurements of the concentration of 230Thxs in the sediment. 230Thxs is a constant flux proxy and may be used to assess variations in the sedimentation rates through the core sections of interest. Following this approach, we present a new age model for Site 1061 that allows us to better determine the temporal behaviour of the Laschamp excursion with greater accuracy and known uncertainty. Palaeomagnetic measurements of discrete samples from four cores reveal a single excursional feature, across an interval of 30 cm, associated with a broader palaeointensity low. The excursion is characterised by rapid transitions (less than 200 years) between a stable normal polarity and a partially-reversed, polarity. Peaks in inclination either side of the directional excursion indicate periods of time when the local field is dominated by vertical flux patches. Similar behaviour has been observed in records of the Iceland Basin Excursion from the same region. The palaeointensity record is in good agreement between the two sites. The palaeointensity record shows two prominent minima, the first associated with the Laschamp excursion at 41 ka and the second at ~34 ka, possibly associated with the elusive 'Mono-Lake' excursion. Similar field intensity behaviour has been observed during the Blake excursion suggesting that the geomagnetic field stability may be reduced for relatively long durations, potentially up to tens of thousands of years. Using the 230Thxs derived sedimentation rate, we determine that the directional excursion at this location was no longer than ~400 years, occurring within a palaeointensity low lasting 2000 years. We compare this record with previously published records of the Blake and Iceland Basin Excursions from nearby locations. The Laschamp excursion at this location appears to be much shorter in duration than the Blake and Iceland Basin excursions.

Power and energy computational models for the design and simulation of hybrid-electric combat vehicles

NASA Astrophysics Data System (ADS)

Smith, Wilford; Nunez, Patrick

2005-05-01

This paper describes the work being performed under the RDECOM Power and Energy (P&E) program (formerly the Combat Hybrid Power System (CHPS) program) developing hybrid power system models and integrating them into larger simulations, such as OneSAF, that can be used to find duty cycles to feed designers of hybrid power systems. This paper also describes efforts underway to link the TARDEC P&E System Integration Lab (SIL) in San Jose CA to the TARDEC Ground Vehicle Simulation Lab (GVSL) in Warren, MI. This linkage is being performed to provide a methodology for generating detailed driver profiles for use in the development of vignettes and mission profiles for system design excursions.

Bound on largest r ∼< 0.1 from sub-Planckian excursions of inflaton

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

Chatterjee, Arindam; Mazumdar, Anupam, E-mail: arindam@hri.res.in, E-mail: a.mazumdar@lancaster.ac.uk

2015-01-01

In this paper we will discuss the range of large tensor to scalar ratio, r, obtainable from a sub-Planckian excursion of a single, slow roll driven inflaton field. In order to obtain a large r for such a scenario one has to depart from a monotonic evolution of the slow roll parameters in such a way that one still satisfies all the current constraints of \\texttt(Planck), such as the scalar amplitude, the tilt in the scalar power spectrum, running and running of the tilt close to the pivot scale. Since the slow roll parameters evolve non-monotonically, we will also considermore » the evolution of the power spectrum on the smallest scales, i.e. at P{sub s}(k ∼ 10{sup 16} Mpc{sup −1})∼< 10{sup −2}, to make sure that the amplitude does not become too large. All these constraints tend to keep the tensor to scalar ratio, r ∼< 0.1. We scan three different kinds of potential for supersymmetric flat directions and obtain the benchmark points which satisfy all the constraints. We also show that it is possible to go beyond r ∼> 0.1 provided we relax the upper bound on the power spectrum on the smallest scales.« less

Rapid directional changes associated with a 6.5 kyr-long Blake geomagnetic excursion at the Blake-Bahama Outer Ridge

NASA Astrophysics Data System (ADS)

Bourne, Mark; Mac Niocaill, Conall; Thomas, Alex L.; Knudsen, Mads Faurschou; Henderson, Gideon M.

2012-06-01

Geomagnetic excursions are recognized as intrinsic features of the Earth's magnetic field. High-resolution records of field behaviour, captured in marine sedimentary cores, present an opportunity to determine the temporal and geometric character of the field during geomagnetic excursions and provide constraints on the mechanisms producing field variability. We present here the highest resolution record yet published of the Blake geomagnetic excursion (∼125 ka) measured in three cores from Ocean Drilling Program (ODP) Site 1062 on the Blake-Bahama Outer Ridge. The Blake excursion has a controversial structure and timing but these cores have a sufficiently high sedimentation rate (∼10 cm ka-1) to allow detailed reconstruction of the field behaviour at this site during the excursion. Palaeomagnetic measurements of the cores reveal rapid transitions (<500 yr) between the contemporary stable normal polarity and a completely reversed state of long duration which spans a stratigraphic interval of 0.7 m. We determine the duration of the reversed state during the Blake excursion using oxygen isotope stratigraphy, combined with 230Th excess measurements to assess variations in the sedimentation rates through the sections of interest. This provides an age and duration for the Blake excursion with greater accuracy and with constrained uncertainty. We date the directional excursion as falling between 129 and 122 ka with a duration for the deviation of 6.5±1.3 kyr. The long duration of this interval and the fully reversed field suggest the existence of a pseudo-stable, reversed dipole field component during the excursion and challenge the idea that excursions are always of short duration.

High-resolution palaeomagnetic records of the Laschamp geomagnetic excursion from ODP Sites 1061 and 1062

NASA Astrophysics Data System (ADS)

Bourne, M. D.; Henderson, G. M.; Thomas, A. L.; Mac Niocaill, C.

2012-12-01

The Laschamp geomagnetic excursion (~41 ka) was a brief global deviation in geomagnetic field behaviour from that expected during normal secular variation. Previously published records suggest rapid changes in field direction and a concurrent substantial decrease in field intensity. We present here high-resolution palaeomagnetic records of the Laschamp excursion obtained from two Ocean Drilling Program (ODP) Sites 1061 and 1062 on the Blake-Bahama Outer Ridge (ODP Leg 172) and compare this record with previously published records of the Blake and Iceland Basin Excursions. Relatively high sedimentation rates (>10 cm kyr-1) at these locations allow the determination of transitional field behaviour during the excursion. Rather than assuming a constant sedimentation rate between assigned age tie-points, we employ measurements of 230Thxs concentration in the sediment to assess variations in the sedimentation rates through the core sections of interest. This allows us to better determine the temporal behaviour of the Laschamp excursion with greater accuracy and known uncertainty. The Laschamp excursion at this location appears to be much shorter in duration than the Blake and Iceland Basin excursions. Palaeomagnetic measurements of discrete samples from four cores reveal a single excursional feature, across an interval of 30 cm, associated with a broader palaeointensity low. The excursion is characterised by rapid transitions (less than 500 years) between a stable normal polarity and a partially-reversed, polarity. Peaks in inclination either side of the directional excursion indicate periods of time when the local field is dominated by vertical flux patches. Similar behaviour has been observed in records of the Iceland Basin Excursion from the same region. The palaeointensity record is in good agreement between the two sites. The palaeointensity record shows two minima, where the second dip in intensity is associated with a more limited directional deviation. Similar field intensity behaviour has been observed during the Blake excursion suggesting that the geomagnetic field stability may be reduced for relatively long durations, potentially up to tens of thousands of years.

Analyses of transients for an 800 MW-class accelerator driven transmuter with fertile-free fuels

NASA Astrophysics Data System (ADS)

Maschek, Werner; Suzuki, Tohru; Chen, Xue-Nong; Rineiski, Andrei; Matzerath Boccaccini, Claudia; Mori, Magnus; Morita, Koji

2006-06-01

In the FUTURE Program, the development and application of fertile-free fuels for Accelerator Driven Transmuters (ADTs) has been advanced. To assess the reactor performance and safety behavior of an ADT with so-called dedicated fuels, various transient cases for an 800 MW-class Pb/Bi-cooled ADT were investigated using the SIMMER-III code. The FUTURE ADT also served as vehicle to develop and test ideas on a safety concept for such transmuters. After an extensive ranking procedure, a CERCER fuel with an MgO matrix and a CERMET fuel with a Mo-92 matrix were chosen. The transient scenarios shown here are: spurious beam trip (BT), unprotected loss of flow (ULOF) and unprotected blockage accident (UBA). Since the release of fission gas and helium after cladding failure could induce a significant positive reactivity, the gas-blowdown was investigated for the transient scenarios. The present analyses showed that power excursions could be avoided by the fuel sweep-out from the core under severe accident conditions.

Midtarsal locking, the windlass mechanism, and running strike pattern: A kinematic and kinetic assessment.

PubMed

Bruening, Dustin A; Pohl, Michael B; Takahashi, Kota Z; Barrios, Joaquin A

2018-05-17

Changes in running strike pattern affect ankle and knee mechanics, but little is known about the influence of strike pattern on the joints distal to the ankle. The purpose of this study was to explore the effects of forefoot strike (FFS) and rearfoot strike (RFS) running patterns on foot kinematics and kinetics, from the perspectives of the midtarsal locking theory and the windlass mechanism. Per the midtarsal locking theory, we hypothesized that the ankle would be more inverted in early stance when using a FFS, resulting in decreased midtarsal joint excursions and increased dynamic stiffness. Associated with a more engaged windlass mechanism, we hypothesized that a FFS would elicit increased metatarsophalangeal joint excursions and negative work in late stance. Eighteen healthy female runners ran overground with both FFS and RFS patterns. Instrumented motion capture and a validated multi-segment foot model were used to analyze midtarsal and metatarsophalangeal joint kinematics and kinetics. During early stance in FFS the ankle was more inverted, with concurrently decreased midtarsal eversion (p < 0.001) and abduction excursions (p = 0.003) but increased dorsiflexion excursion (p = 0.005). Dynamic midtarsal stiffness did not differ (p = 0.761). During late stance in FFS, metatarsophalangeal extension was increased (p = 0.009), with concurrently increased negative work (p < 0.001). In addition, there was simultaneously increased midtarsal positive work (p < 0.001), suggesting enhanced power transfer in FFS. Clear evidence for the presence of midtarsal locking was not observed in either strike pattern during running. However, the windlass mechanism appeared to be engaged to a greater extent during FFS. Copyright © 2018 Elsevier Ltd. All rights reserved.

Relative fascicle excursion effects on dynamic strength generation during gait in children with cerebral palsy.

PubMed

Martín Lorenzo, T; Lerma Lara, S; Martínez-Caballero, I; Rocon, E

2015-10-01

Evaluation of muscle structure gives us a better understanding of how muscles contribute to force generation which is significantly altered in children with cerebral palsy (CP). While most muscle structure parameters have shown to be significantly correlated to different expressions of strength development in children with CP and typically developing (TD) children, conflicting results are found for muscle fascicle length. Muscle fascicle length determines muscle excursion and velocity, and contrary to what might be expected, correlations of fascicle length to rate of force development have not been found for children with CP. The lack of correlation between muscle fascicle length and rate of force development in children with CP could be due, on the one hand, to the non-optimal joint position adopted for force generation on the isometric strength tests as compared to the position of TD children. On the other hand, the lack of correlation could be due to the erroneous assumption that muscle fascicle length is representative of sarcomere length. Thus, the relationship between muscle architecture parameters reflecting sarcomere length, such as relative fascicle excursions and dynamic power generation, should be assessed. Understanding of the underlying mechanisms of weakness in children with CP is key for individualized prescription and assessment of muscle-targeted interventions. Findings could imply the detection of children operating on the descending limb of the sarcomere length-tension curve, which in turn might be at greater risk of developing crouch gait. Furthermore, relative muscle fascicle excursions could be used as a predictive variable of outcomes related to crouch gait prevention treatments such as strength training. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Whale of an Interest in Sea Creatures: The Learning Potential of Excursions

ERIC Educational Resources Information Center

Hedges, Helen

2004-01-01

Excursions, or field trips, are a common component of early childhood programs, seen as a means of enriching the curriculum by providing experiences with people, places, and things in the community. Although excursions have been used as a framework for research on children's memory development, research on the efficacy of excursions in terms of…

Nuclear reactor safety device

DOEpatents

Hutter, Ernest

1986-01-01

A safety device is disclosed for use in a nuclear reactor for axially repositioning a control rod with respect to the reactor core in the event of an upward thermal excursion. Such safety device comprises a laminated helical ribbon configured as a tube-like helical coil having contiguous helical turns with slidably abutting edges. The helical coil is disclosed as a portion of a drive member connected axially to the control rod. The laminated ribbon is formed of outer and inner laminae. The material of the outer lamina has a greater thermal coefficient of expansion than the material of the inner lamina. In the event of an upward thermal excursion, the laminated helical coil curls inwardly to a smaller diameter. Such inward curling causes the total length of the helical coil to increase by a substantial increment, so that the control rod is axially repositioned by a corresponding amount to reduce the power output of the reactor.

Intermittent Fermi-Pasta-Ulam Dynamics at Equilibrium

NASA Astrophysics Data System (ADS)

Campbell, David; Danieli, Carlo; Flach, Sergej

The equilibrium value of an observable defines a manifold in the phase space of an ergodic and equipartitioned many-body syste. A typical trajectory pierces that manifold infinitely often as time goes to infinity. We use these piercings to measure both the relaxation time of the lowest frequency eigenmode of the Fermi-Pasta-Ulam chain, as well as the fluctuations of the subsequent dynamics in equilibrium. We show that previously obtained scaling laws for equipartition times are modified at low energy density due to an unexpected slowing down of the relaxation. The dynamics in equilibrium is characterized by a power-law distribution of excursion times far off equilibrium, with diverging variance. The long excursions arise from sticky dynamics close to regular orbits in the phase space. Our method is generalizable to large classes of many-body systems. The authors acknowledge financial support from IBS (Project Code IBS-R024-D1).

Excursive behaviors by female white-tailed deer during estrus at two mid-Atlantic sites

Treesearch

Jeffrey J. Kolodzinski; Lawrence V. Tannenbaum; Lisa I. Muller; David A. Osborn; Kent A. Adams; Mark C. Conner; W. Mark Ford; Karl V. Miller

2010-01-01

Current research suggests that female white-tailed deer (Odocoileus virginianus) will adopt sedentary breeding strategies in populations with an abundance of males and a more active mate-searching strategy in low-density or unbalanced herds. We used GPS collars to document the movements of 10 female deer during the breeding season at two Mid-Atlantic...

A Quaternary Geomagnetic Instability Time Scale

NASA Astrophysics Data System (ADS)

Singer, B. S.

2013-12-01

Reversals and excursions of Earth's geomagnetic field create marker horizons that are readily detected in sedimentary and volcanic rocks worldwide. An accurate and precise chronology of these geomagnetic field instabilities is fundamental to understanding several aspects of Quaternary climate, dynamo processes, and surface processes. For example, stratigraphic correlation between marine sediment and polar ice records of climate change across the cryospheres benefits from a highly resolved record of reversals and excursions. The temporal patterns of dynamo behavior may reflect physical interactions between the molten outer core and the solid inner core or lowermost mantle. These interactions may control reversal frequency and shape the weak magnetic fields that arise during successive dynamo instabilities. Moreover, weakening of the axial dipole during reversals and excursions enhances the production of cosmogenic isotopes that are used in sediment and ice core stratigraphy and surface exposure dating. The Geomagnetic Instability Time Scale (GITS) is based on the direct dating of transitional polarity states recorded by lava flows using the 40Ar/39Ar method, in parallel with astrochronologic age models of marine sediments in which O isotope and magnetic records have been obtained. A review of data from Quaternary lava flows and sediments yields a GITS comprising 10 polarity reversals and 27 excursions during the past 2.6 million years. Nine of the ten reversals bounding chrons and subchrons are associated with 40Ar/39Ar ages of transitionally-magnetized lava flows. The tenth, the Guass-Matuyama chron boundary, is tightly bracketed by 40Ar/39Ar dated ash deposits. Of the 27 well-documented excursions, 14 occurred during the Matuyama chron and 13 during the Brunhes chron; 19 have been dated directly using the 40Ar/39Ar method on transitionally-magnetized volcanic rocks and form the backbone of the GITS. Excursions are clearly not the rare phenomena once thought. Rather, during the Quaternary period, they occur nearly three times as often as full polarity reversals. I will address analytical issues, including the size and consistency of system blanks, that have led to the recognition of minor (1%) discrepencies between the 40Ar/39Ar age for a particular reversal or excursion and the best astrochronologic estimates from ODP sediment cores. For example, re-analysis of lava flows from Haleakala volcano, Maui that record in detail the Matuyama-Brunhes polarity reversal have been undertaken with blanks an order of magntitude smaller and more stable than was common a decade ago. Using the modern astrochronologic calibration of 28.201 Ma for the age of the Fish Canyon sanidine standard, results thus far yield an 40Ar/39Ar age of 772 × 11 ka for the reversal that is identical to the most precise and accurate astrochronologic age of 773 × 2 ka for this reversal from ODP cores. Similarly, new dating of sanidine in the Cerro Santa Rosa I rhyolite dome, New Mexico reveals an age of 932 × 5 ka for the excursion it records, in perfect agreement with astrochronologically dated ODP core records. Work underway aims at refining the 40Ar/39Ar ages that underpin the entire GITS by further eliminating the bias between the radioisotopic and astrochronologically determined ages for several reversals and excursions.

Relationship of the functional movement screen in-line lunge to power, speed, and balance measures.

PubMed

Hartigan, Erin H; Lawrence, Michael; Bisson, Brian M; Torgerson, Erik; Knight, Ryan C

2014-05-01

The in-line lunge of the Functional Movement Screen (FMS) evaluates lateral stability, balance, and movement asymmetries. Athletes who score poorly on the in-line lunge should avoid activities requiring power or speed until scores are improved, yet relationships between the in-line lunge scores and other measures of balance, power, and speed are unknown. (1) Lunge scores will correlate with center of pressure (COP), maximum jump height (MJH), and 36.6-meter sprint time and (2) there will be no differences between limbs on lunge scores, MJH, or COP. Descriptive laboratory study. Level 3. Thirty-seven healthy, active participants completed the first 3 tasks of the FMS (eg, deep squat, hurdle step, in-line lunge), unilateral drop jumps, and 36.6-meter sprints. A 3-dimensional motion analysis system captured MJH. Force platforms measured COP excursion. A laser timing system measured 36.6-m sprint time. Statistical analyses were used to determine whether a relationship existed between lunge scores and COP, MJH, and 36.6-m speed (Spearman rho tests) and whether differences existed between limbs in lunge scores (Wilcoxon signed-rank test), MJH, and COP (paired t tests). Lunge scores were not significantly correlated with COP, MJH, or 36.6-m sprint time. Lunge scores, COP excursion, and MJH were not statistically different between limbs. Performance on the FMS in-line lunge was not related to balance, power, or speed. Healthy participants were symmetrical in lunging measures and MJH. Scores on the FMS in-line lunge should not be attributed to power, speed, or balance performance without further examination. However, assessing limb symmetry appears to be clinically relevant.

The effect of muscle excursion on muscle recovery after tendon repair in a neglected tendon injury: a study in rabbit soleus muscles.

PubMed

Jeon, Suk Ha; Chung, Moon Sang; Baek, Goo Hyun; Lee, Young Ho; Gong, Hyun Sik

2011-01-01

We attempted to determine whether muscle excursion observed during operation can be a prognostic indicator of muscle recovery after delayed tendon repair in a rabbit soleus model. Eighteen rabbits underwent tenotomy of the soleus muscles bilaterally and were divided into three groups according to the period from tenotomy to repair. The tendons of each group were repaired 2, 4, and 6 weeks after tenotomy. The excursion of each soleus muscle was measured at the time of tenotomy (baseline), at 2, 4, 6 weeks after tenotomy, and 8 weeks after tendon repair. The amount of muscle recovery after tendon repair in terms of muscle excursion independently depended on the timing of repair and on the muscle excursion observed during repair. The regression model predicted that the muscle excursion recovered on average by 0.6% as the muscle excursion at the time of repair increased by 1% after adjusting for the timing of repair. This study suggests that measuring the muscle excursion during tendon repair may help physicians estimate the potential of muscle recovery in cases of delayed tendon repair. Copyright © 2010 Orthopaedic Research Society.

Transients control in Raman fiber amplifiers

NASA Astrophysics Data System (ADS)

Freitas, Marcio; Givigi, Sidney N., Jr.; Klein, Jackson; Calmon, Luiz C.; de Almeida, Ailson R.

2004-11-01

Raman fiber amplifiers (RFA) are being used in optical transmission communication systems in the recent years due to their advantages in comparison to erbium-doped fiber amplifiers (EDFA). Recently the analysis of RFAs dynamic response and transients control has become important in order to predict the system response to add/drop of channels or cable cuts in optical systems, and avoid impairments caused by the power transients. Fast signal power transients in the surviving channels are caused by the cross-gain saturation effect in RFA and the slope of the gain saturation characteristics determines the steady-state surviving channel power excursion. We are presenting the modeling and analysis of power transients and its control using a pump control method for a single and multi-pump scheme.

Fueled By Wealth, Funneled By Politics: The Dominance of Domestic Drivers of Arms Procurement in Southeast Asia

DTIC Science & Technology

2015-12-01

in driving arms procurements in Malaysia , Indonesia, and Singapore: availability of resources, domestic politics, external threats, and force...could incite more frequent excursions toward competitive arms dynamics. 14. SUBJECT TERMS Malaysia , Indonesia, Singapore, Southeast Asia, arms...This thesis investigates the following four factors to determine which are most powerful in driving arms procurements in Malaysia , Indonesia, and

A Comparison of two Brunhes Chron Geomagnetic Excursions Recorded by Neighbouring North Atlantic Sites (ODP Sites 1062 and 1063)

NASA Astrophysics Data System (ADS)

Bourne, M.; Mac Niocaill, C.; Knudsen, M. F.; Thomas, A. L.; Henderson, G. M.

2012-04-01

A full picture of geomagnetic field behaviour during the Blake excursion is currently limited by a paucity of robust, high-resolution records of this ambiguous event. Some records seem to point towards a 'double-excursion' character whilst others fail to record the Blake excursion at all. We present here a high-resolution record of the Blake excursion obtained from Ocean Drilling Program (ODP) Site 1062 on the Blake Outer Ridge (ODP Leg 172). Palaeomagnetic measurements in three cores reveal a single excursional feature associated with a broad palaeointensity low, characterised by rapid transitions (less than 500 years) between a stable normal polarity and a fully-reversed, pseudo-stable polarity. A relatively high sedimentation rate (~10 cm kyr-1) allows the determination of transitional field behaviour during the excursion. Rather than assuming a constant sedimentation rate between assigned age tie-points, we employ measurements of 230Thxs concentrations in the sediment to assess variations in the sedimentation rates through the core sections of interest. This allows us to determine an age and duration for the two excursions with greater accuracy and known uncertainty. Our new age model gives an age of 127 ka for the midpoint of the Blake event at Site 1062. The age model also gives a duration for the directional excursion of 7.1±1.6 kyr. This duration is similar to that previously reported for the Iceland Basin Excursion (~185 ka) from the nearby Bermuda Rise (ODP Site 1063), which recorded a ~7-8 kyr event. Similarly, a high sedimentation rate (10-15 cm kyr-1) at this site allows a high-resolution reconstruction of the geomagnetic field behaviour during the Iceland Basin Excursion. The Site 1063 palaeomagnetic record suggests more complicated behaviour than that of the Blake excursion at Site 1062. Instead, transitional VGP paths are characterised by stop-and-go behaviour between VGP clusters that may be related to long-standing thermo-dynamic features of the core-mantle system. The long duration of fully reversed directions at the two sites is somewhat longer than that typically assumed for excursions and appears to suggest that there may be a degree of stability associated with the two excursional events. We will present a comparison of the geomagnetic field behaviour of the two excursions as recorded at these two sites.

The effect of spinal position on sciatic nerve excursion during seated neural mobilisation exercises: an in vivo study using ultrasound imaging

PubMed Central

Ellis, Richard; Osborne, Samantha; Whitfield, Janessa; Parmar, Priya; Hing, Wayne

2017-01-01

Objectives Research has established that the amount of inherent tension a peripheral nerve tract is exposed to influences nerve excursion and joint range of movement (ROM). The effect that spinal posture has on sciatic nerve excursion during neural mobilisation exercises has yet to be determined. The purpose of this research was to examine the influence of different sitting positions (slump-sitting versus upright-sitting) on the amount of longitudinal sciatic nerve movement during different neural mobilisation exercises commonly used in clinical practice. Methods High-resolution ultrasound imaging followed by frame-by-frame cross-correlation analysis was used to assess sciatic nerve excursion. Thirty-four healthy participants each performed three different neural mobilisation exercises in slump-sitting and upright-sitting. Means comparisons were used to examine the influence of sitting position on sciatic nerve excursion for the three mobilisation exercises. Linear regression analysis was used to determine whether any of the demographic data represented predictive variables for longitudinal sciatic nerve excursion. Results There was no significant difference in sciatic nerve excursion (across all neural mobilisation exercises) observed between upright-sitting and slump-sitting positions (P = 0.26). Although greater body mass index, greater knee ROM and younger age were associated with higher levels of sciatic nerve excursion, this model of variables offered weak predictability (R2 = 0.22). Discussion Following this study, there is no evidence that, in healthy people, longitudinal sciatic nerve excursion differs significantly with regards to the spinal posture (slump-sitting and upright-sitting). Furthermore, although some demographic variables are weak predictors, the high variance suggests that there are other unknown variables that may predict sciatic nerve excursion. It can be inferred from this research that clinicians can individualise the design of seated neural mobilisation exercises, using different seated positions, based upon patient comfort and minimisation of neural mechanosensitivity with the knowledge that sciatic nerve excursion will not be significantly influenced. PMID:28559669

Reliability and feasibility of gait initiation centre-of-pressure excursions using a Wii® Balance Board in older adults at risk of falling.

PubMed

Lee, James; Webb, Graham; Shortland, Adam P; Edwards, Rebecca; Wilce, Charlotte; Jones, Gareth D

2018-04-17

Impairments in dynamic balance have a detrimental effect in older adults at risk of falls (OARF). Gait initiation (GI) is a challenging transitional movement. Centre of pressure (COP) excursions using force plates have been used to measure GI performance. The Nintendo Wii Balance Board (WBB) offers an alternative to a standard force plate for the measurement of CoP excursion. To determine the reliability of COP excursions using the WBB, and its feasibility within a 4-week strength and balance intervention (SBI) treating OARF. Ten OARF subjects attending SBI and ten young healthy adults, each performed three GI trials after 10 s of quiet stance from a standardised foot position (shoulder width) before walking forward 3 m to pick up an object. Averaged COP mediolateral (ML) and anteroposterior (AP) excursions (distance) and path-length time (GI-onset to first toe-off) were analysed. WBB ML (0.866) and AP COP excursion (0.895) reliability (ICC 3,1 ) was excellent, and COP path-length reliability was fair (0.517). Compared to OARF, healthy subjects presented with larger COP excursion in both directions and shorter COP path length. OARF subjects meaningfully improved their timed-up-and-go and ML COP excursion between weeks 1-4, while AP COP excursions, path length, and confidence-in-balance remained stable. COP path length and excursion directions probably measure different GI postural control attributes. Limitations in WBB accuracy and precision in transition tasks needs to be established before it can be used clinically to measure postural aspects of GI viably. The WBB could provide valuable clinical evaluation of balance function in OARF.

Effect of Random Thermal Spikes on Stirling Convertor Heater Head Reliability

NASA Technical Reports Server (NTRS)

Shah, Ashwin R.; Korovaichuk, Igor; Halford, Gary R.

2004-01-01

Onboard radioisotope power systems being developed to support future NASA exploration missions require reliable design lifetimes of up to 14 yr and beyond. The structurally critical heater head of the high-efficiency developmental Stirling power convertor has undergone extensive computational analysis of operating temperatures (up to 650 C), stresses, and creep resistance of the thin-walled Inconel 718 bill of material. Additionally, assessment of the effect of uncertainties in the creep behavior of the thin-walled heater head, the variation in the manufactured thickness, variation in control temperature, and variation in pressure on the durability and reliability were performed. However, it is possible for the heater head to experience rare incidences of random temperature spikes (excursions) of short duration. These incidences could occur randomly with random magnitude and duration during the desired mission life. These rare incidences could affect the creep strain rate and therefore the life. The paper accounts for these uncertainties and includes the effect of such rare incidences, random in nature, on the reliability. The sensitivities of variables affecting the reliability are quantified and guidelines developed to improve the reliability are outlined. Furthermore, the quantified reliability is being verified with test data from the accelerated benchmark tests being conducted at the NASA Glenn Research Center.

Reliability-Based Life Assessment of Stirling Convertor Heater Head

NASA Technical Reports Server (NTRS)

Shah, Ashwin R.; Halford, Gary R.; Korovaichuk, Igor

2004-01-01

Onboard radioisotope power systems being developed and planned for NASA's deep-space missions require reliable design lifetimes of up to 14 yr. The structurally critical heater head of the high-efficiency Stirling power convertor has undergone extensive computational analysis of operating temperatures, stresses, and creep resistance of the thin-walled Inconel 718 bill of material. A preliminary assessment of the effect of uncertainties in the material behavior was also performed. Creep failure resistance of the thin-walled heater head could show variation due to small deviations in the manufactured thickness and in uncertainties in operating temperature and pressure. Durability prediction and reliability of the heater head are affected by these deviations from nominal design conditions. Therefore, it is important to include the effects of these uncertainties in predicting the probability of survival of the heater head under mission loads. Furthermore, it may be possible for the heater head to experience rare incidences of small temperature excursions of short duration. These rare incidences would affect the creep strain rate and, therefore, the life. This paper addresses the effects of such rare incidences on the reliability. In addition, the sensitivities of variables affecting the reliability are quantified, and guidelines developed to improve the reliability are outlined. Heater head reliability is being quantified with data from NASA Glenn Research Center's accelerated benchmark testing program.

The Long-term Light Curves of X-ray Binaries Contain Simultaneous Periodic and Random Components

NASA Technical Reports Server (NTRS)

White, Nicholas E. (Technical Monitor); Boyd, Patricia T.; Smale, Alan P.

2002-01-01

LMC X-3 and Cyg X-2 show large amplitude X-ray fluctuations that have been attributed to a warped accretion disk. Cyg X-3 displays high amplitude, apparently non-periodic oscillations. We reanalyze these systems using RXTE ASM data and time-frequency decomposition techniques. We find that the long-term variations in Cyg X-2 can be completely characterized by excursions whose durations are integer multiples of the orbital period, including one essentially identical to the reported "period" of 78 days. Cyg X-3 can be characterized in terms of integer multiples of a 71-day fundamental period unrelated to the 4.8 day orbital period, but suggestively close to the approximately equal to greater than 60 day reported precession period of the relativistic jet inferred from recent radio observations. The long-term excursions of LMC X-3 are related to each other by rational fractions, suggesting the characteristic time scale is 10.594 days, shorter than any observed excursion to date. We explore the phase space evolution of the light curves using a natural embedding and find that all three systems possess two rotation centers that organize the phase space trajectories, one of low luminosity and the other of high luminosity. The implications of this repeatable behavior on generic models of accretion disk dynamics and mass transfer variability are explored.

Thermal anomalies of the transmitter experiment package on the communications technology satellite

NASA Technical Reports Server (NTRS)

Alexovich, R. E.; Curren, A. N.

1979-01-01

The causes of four temporary thermal-control-system malfunctions that gave rise to unexpected temperature excursions in the 12-gigahertz, 200-watt transmitter experiment package (TEP) on the Communications Technology Satellite were investigated. The TEP consists of a nominal 200-watt output stage tube (OST), a supporting power-processing system (PPS), and a variable-conductance heat-pipe system (VCHPS). The VCHPS, which uses three heat pipes to conduct heat from the body of the OST to a radiator fin, was designed to maintain the TEP at safe operating temperatures at all operating conditions. On four occasions during 1977, all near the spring and fall equinoxes, the OST body temperature and related temperatures displayed sudden, rapid, and unexpected rises above normal levels while the TEP was operating at essentially constant, normal conditions. The temperature excursions were terminated without TEP damage by reducing the radio frequency (RF) output power of the OST. Between the anomalies and since the fourth, the thermal control system has apparently functioned as designed. The results indicate the most probable cause of the temperature anomalies is depriming of the arteries in the variable-conductance heat pipes. A mode was identified in which the TEP, as presently configured, may operate with stable temperatures and with minimum change in performance level.

Geometry and scaling laws of excursion and iso-sets of enstrophy and dissipation in isotropic turbulence

NASA Astrophysics Data System (ADS)

Elsas, José Hugo; Szalay, Alexander S.; Meneveau, Charles

2018-04-01

Motivated by interest in the geometry of high intensity events of turbulent flows, we examine the spatial correlation functions of sets where turbulent events are particularly intense. These sets are defined using indicator functions on excursion and iso-value sets. Their geometric scaling properties are analysed by examining possible power-law decay of their radial correlation function. We apply the analysis to enstrophy, dissipation and velocity gradient invariants Q and R and their joint spatial distributions, using data from a direct numerical simulation of isotropic turbulence at Reλ ≈ 430. While no fractal scaling is found in the inertial range using box-counting in the finite Reynolds number flow considered here, power-law scaling in the inertial range is found in the radial correlation functions. Thus, a geometric characterisation in terms of these sets' correlation dimension is possible. Strong dependence on the enstrophy and dissipation threshold is found, consistent with multifractal behaviour. Nevertheless, the lack of scaling of the box-counting analysis precludes direct quantitative comparisons with earlier work based on multifractal formalism. Surprising trends, such as a lower correlation dimension for strong dissipation events compared to strong enstrophy events, are observed and interpreted in terms of spatial coherence of vortices in the flow.

Autonomous excursions using tablets and smartphones

NASA Astrophysics Data System (ADS)

Marra, Wouter; Groothengel, Marin; van de Grint, Liesbeth; Karssenberg, Derek; Stouthamer, Esther

2017-04-01

Excursions and fieldworks are valuable components for geosciences education. However, field activities can be time consuming for teachers and pose a logistical challenge to fit in regular courses. Furthermore, the participation of students diminishes with group size in case of instructor-led outings. We are developing excursions that students can follow autonomously without a teacher present, using instructions, assignments and background information on tablets and smartphones. The goal of this approach is to increase the level of active participation, and to reduce logistical and time table issues. We developed a bike-excursion about the landscape and geology in the vicinity of our University. Such excursion was on the wish-list for several years, but posed a logistical challenge for the group of about 80 students in the available timeslot. In our approach, students had a time-window of two weeks in which they could finish the excursion in groups of 2. 8-Inch tablets with water- and shock-proof cases were available for this excursion. For the excursion we used three apps: 1) IZI-Travel for providing the route, spoken navigation instructions, spoken explanations at stops, location-related images, assignments as text, and multiple-choose questions. 2) PDF-Maps for providing geo-referenced maps. 3) ESRI Collector which the students used to digitize polygons on a map, and to collect geo-referenced photos with explanation. These data were answers to assignments and were later used in a tutorial on campus. The assignments where students had to collect data, and the small group size (pairs) increased the level of active participation. The use of a final tutorial on campus was important for the autonomous excursion, as it gave students the opportunity to discuss their observations and questions with their teacher. The developed teaching materials are available online to use and adapt for others. Parts could be useful for other universities and schools in the vicinity of the excursion location.

49 CFR 38.177 - Ferries, excursion boats and other vessels. [Reserved

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 1 2014-10-01 2014-10-01 false Ferries, excursion boats and other vessels. [Reserved] 38.177 Section 38.177 Transportation Office of the Secretary of Transportation AMERICANS WITH....177 Ferries, excursion boats and other vessels. [Reserved] ...

49 CFR 38.177 - Ferries, excursion boats and other vessels. [Reserved

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 1 2010-10-01 2010-10-01 false Ferries, excursion boats and other vessels. [Reserved] 38.177 Section 38.177 Transportation Office of the Secretary of Transportation AMERICANS WITH....177 Ferries, excursion boats and other vessels. [Reserved] ...

49 CFR 38.177 - Ferries, excursion boats and other vessels. [Reserved

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 1 2011-10-01 2011-10-01 false Ferries, excursion boats and other vessels. [Reserved] 38.177 Section 38.177 Transportation Office of the Secretary of Transportation AMERICANS WITH....177 Ferries, excursion boats and other vessels. [Reserved] ...

49 CFR 38.177 - Ferries, excursion boats and other vessels. [Reserved

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 1 2013-10-01 2013-10-01 false Ferries, excursion boats and other vessels. [Reserved] 38.177 Section 38.177 Transportation Office of the Secretary of Transportation AMERICANS WITH....177 Ferries, excursion boats and other vessels. [Reserved] ...

49 CFR 38.177 - Ferries, excursion boats and other vessels. [Reserved

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 1 2012-10-01 2012-10-01 false Ferries, excursion boats and other vessels. [Reserved] 38.177 Section 38.177 Transportation Office of the Secretary of Transportation AMERICANS WITH....177 Ferries, excursion boats and other vessels. [Reserved] ...

Effect of Stress-Strain Behavior on Low-Cycle Fatigue of Alpha-Beta Titanium Alloys.

DTIC Science & Technology

1980-11-21

and strain excursion, such a curve would appear to fit much of the high temperature hold-time data compiled by Krempl and Wundt [21]. Thus, it might...34Mechanische Relaxation von Kupfer-Einkristallen," Phys. Stat. Sol. 3, 111-120. 21. Krempl, E. and Wundt , B. M., (1971), Hold-Time Effects in High- Temperature Low-Cycle Fatigue, ASTM STP 489. 26 Low

Comparison of longitudinal excursion of a nerve-phantom model using quantitative ultrasound imaging and motion analysis system methods: A convergent validity study.

PubMed

Paquette, Philippe; El Khamlichi, Youssef; Lamontagne, Martin; Higgins, Johanne; Gagnon, Dany H

2017-08-01

Quantitative ultrasound imaging is gaining popularity in research and clinical settings to measure the neuromechanical properties of the peripheral nerves such as their capability to glide in response to body segment movement. Increasing evidence suggests that impaired median nerve longitudinal excursion is associated with carpal tunnel syndrome. To date, psychometric properties of longitudinal nerve excursion measurements using quantitative ultrasound imaging have not been extensively investigated. This study investigates the convergent validity of the longitudinal nerve excursion by comparing measures obtained using quantitative ultrasound imaging with those determined with a motion analysis system. A 38-cm long rigid nerve-phantom model was used to assess the longitudinal excursion in a laboratory environment. The nerve-phantom model, immersed in a 20-cm deep container filled with a gelatin-based solution, was moved 20 times using a linear forward and backward motion. Three light-emitting diodes were used to record nerve-phantom excursion with a motion analysis system, while a 5-cm linear transducer allowed simultaneous recording via ultrasound imaging. Both measurement techniques yielded excellent association ( r  = 0.99) and agreement (mean absolute difference between methods = 0.85 mm; mean relative difference between methods = 7.48 %). Small discrepancies were largely found when larger excursions (i.e. > 10 mm) were performed, revealing slight underestimation of the excursion by the ultrasound imaging analysis software. Quantitative ultrasound imaging is an accurate method to assess the longitudinal excursion of an in vitro nerve-phantom model and appears relevant for future research protocols investigating the neuromechanical properties of the peripheral nerves.

Dynamics of the earth magnetic field in the 10-75 kyr period comprising the Laschamp and Mono Lake excursions: New results from the French Chaîne des Puys in a global perspective

NASA Astrophysics Data System (ADS)

Laj, Carlo; Guillou, Hervé; Kissel, Catherine

2014-02-01

We report here on a new paleomagnetic (directions and intensities) and coupled K/Ar and 40Ar/39Ar analysis of 35 different flows, emplaced in the Chaîne des Puys during the 75 to 10 kyr interval, which contains the Mono Lake and Laschamp excursions. There is a remarkable agreement between the new set of absolute volcanic intensities and published sedimentary (GLOPIS-75) and cosmogenic (10Be and 36Cl) records. The Laschamp and Mono Lake excursions are clearly revealed by a very significant intensity drop at 41.2±1.6 ka and 34.2±1.2 ka respectively. The duration of the Laschamp excursion is ˜1500 yr and about 640 yr when the drop of paleointensity or the directional change are considered respectively. The intensity drop at the Mono Lake is twice as short. In the ˜7 ka interval separating the two excursions, the field intensity recovers to almost non-transitional values. The rate of decrease of the field intensity during these excursions attains 18 nT/yr for the Laschamp and even greater value (33 nT/yr) for the Mono Lake. This figure is, for the Laschamp excursion, similar to the present field intensity decrease in the last two centuries so that one may wonder whether such a high rate of change may be characteristic of an impending geomagnetic event (reversal or excursion). We suggest that the name Auckland excursion should be used for the present-day called Mono Lake.

Condylar motion in children with primary dentition during lateral excursion.

PubMed

Yamasaki, Youichi; Hayasaki, Haruaki; Nishi, Megumi; Nakata, Shiho; Nakata, Minoru

2002-07-01

Normal development of primary and mixed dentition is indispensable for establishing a healthy mandibular function of the permanent dentition. Because condylar movements are crucial for mandibular function, extensive studies have been reported. However, most of these studies have dealt with mandibular functions in adults, and there is less known about children with primary dentition. The purpose of this study was to clarify the condylar movements during lateral excursions in children with primary dentition and compare these movements with those of adults from the viewpoint of functional development. With use of an optoelectronic recording system with six degrees of freedom, the lateral excursions of 24 children and 20 young women, with sound dentition, were recorded at 100 Hz. The results show that the balancing side condyle of the children had a significantly smaller vertical excursion and a significantly larger anteroposterior excursion than that of adults, indicating the shallower and more anteriorly directed movements of the entire mandible during lateral excursions in children with primary dentition.

Precision measurement of the local bias of dark matter halos

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

Lazeyras, Titouan; Wagner, Christian; Schmidt, Fabian

2016-02-01

We present accurate measurements of the linear, quadratic, and cubic local bias of dark matter halos, using curved 'separate universe' N-body simulations which effectively incorporate an infinite-wavelength overdensity. This can be seen as an exact implementation of the peak-background split argument. We compare the results with the linear and quadratic bias measured from the halo-matter power spectrum and bispectrum, and find good agreement. On the other hand, the standard peak-background split applied to the Sheth and Tormen (1999) and Tinker et al. (2008) halo mass functions matches the measured linear bias parameter only at the level of 10%. The predictionmore » from the excursion set-peaks approach performs much better, which can be attributed to the stochastic moving barrier employed in the excursion set-peaks prediction. We also provide convenient fitting formulas for the nonlinear bias parameters b{sub 2}(b{sub 1}) and b{sub 3}(b{sub 1}), which work well over a range of redshifts.« less

Excursions out-of-lane versus standard deviation of lateral position as outcome measure of the on-the-road driving test.

PubMed

Verster, Joris C; Roth, Thomas

2014-07-01

The traditional outcome measure of the Dutch on-the-road driving test is the standard deviation of lateral position (SDLP), the weaving of the car. This paper explores whether excursions out-of-lane are a suitable additional outcome measure to index driving impairment. A literature search was conducted to search for driving tests that used both SDLP and excursions out-of-lane as outcome measures. The analyses were limited to studies examining hypnotic drugs because several of these drugs have been shown to produce next-morning sedation. Standard deviation of lateral position was more sensitive in demonstrating driving impairment. In fact, solely relying on excursions out-of-lane as outcome measure incorrectly classifies approximately half of impaired drives as unimpaired. The frequency of excursions out-of-lane is determined by the mean lateral position within the right traffic lane. Defining driving impairment as having a ΔSDLP > 2.4 cm, half of the impaired driving tests (51.2%, 43/84) failed to produce excursions out-of-lane. Alternatively, 20.9% of driving tests with ΔSDLP < 2.4 cm (27/129) had at least one excursion out-of-lane. Excursions out-of-lane are neither a suitable measure to demonstrate driving impairment nor is this measure sufficiently sensitive to differentiate adequately between differences in magnitude of driving impairment. Copyright © 2014 John Wiley & Sons, Ltd.

Geomagnetic Excursions and High-Latitude Paleomagnetic Records of Glaciomarine Sediments from the Western Greenland Margin (Baffin Bay)

NASA Astrophysics Data System (ADS)

Richter, C.; Jensen, S. R.; Acton, G. D.; Evans, H. F.

2017-12-01

We present new paleomagnetic results from Quaternary sediment samples recovered during the Baffin Bay Scientific Coring Expedition conducted by the JOIDES Resolution in 2012. The expedition recovered well-preserved core material from the Arctic Basin, providing an outstanding opportunity for the study of the behavior of the geomagnetic field at high latitude. We analyzed material from 12 sites cored at latitudes between 74°45.32'N and 75°46.68'N in the Melville Bay region (Cape York and Melville Ridge) of Baffin Bay located at an average water depth of 394 m. The Quaternary glaciomarine sediments are up to 150 m thick and consist of very soft diatom-bearing muds to clast-rich sandy and muddy diamicts, which suggest deposition in a subglacial to ice-procimal environment. We carried out paleomagnetic and rock magnetic measurements on the shipboard cryogenic magnetometer at 5-cm resolution on 32 split-core sections and a selected number of discrete samples, and recently processed measurements taken at 1-cm resolution on eight U-channel samples from the uppermost Holocene part of the section. Stepwise demagnetization of the NRM demonstrates excellent demagnetization behavior, with a viscous isothermal remanent magnetization overprint, induced by the coring and sampling process, and typically removed by the 20 mT demagnetization step. The magnetic inclination data are characterized by steep, 80°, normal inclinations, consistent with the site position near the North Pole. Thermal demagnetization, magnetic susceptibility, isothermal remanent magnetization, and hysteresis parameters indicate that the primary magnetic carrier consists of a low-coercivity mineral, e.g., magnetite and/or titanomagnetite, with minor traces of higher-coercivity minerals. Well-developed geomagnetic excursions in the upper part of the section can be correlated between several sites. Although dating of these sediments remains a challenge because of the lack of carbonates we will discuss possible age models and use them to assign ages to the geomagnetic excursions.

46 CFR 2.01-45 - Excursion permit.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., on Coast Guard Form CG-950, Application for Excursion Permit. If, after inspection, permission is... the application process for excursion permits for inspected passenger vessels are contained in §§ 71.10, 115.204, or 176.204 of this chapter. Details concerning the application process for special...

High temperature furnace

DOEpatents

Borkowski, Casimer J.

1976-08-03

A high temperature furnace for use above 2000.degree.C is provided that features fast initial heating and low power consumption at the operating temperature. The cathode is initially heated by joule heating followed by electron emission heating at the operating temperature. The cathode is designed for routine large temperature excursions without being subjected to high thermal stresses. A further characteristic of the device is the elimination of any ceramic components from the high temperature zone of the furnace.

46 CFR 115.204 - Permit to carry excursion party.

Code of Federal Regulations, 2010 CFR

2010-10-01

... jacket, fire safety, and manning standards applicable to a vessel in the service for which the excursion... crew required, any additional lifesaving or safety equipment required, the route for which the permit... applicable minimum safety standards when issuing an excursion permit. In particular, a vessel that is being...

46 CFR 115.204 - Permit to carry excursion party.

Code of Federal Regulations, 2012 CFR

2012-10-01

... jacket, fire safety, and manning standards applicable to a vessel in the service for which the excursion... crew required, any additional lifesaving or safety equipment required, the route for which the permit... applicable minimum safety standards when issuing an excursion permit. In particular, a vessel that is being...

46 CFR 115.204 - Permit to carry excursion party.

Code of Federal Regulations, 2011 CFR

2011-10-01

... jacket, fire safety, and manning standards applicable to a vessel in the service for which the excursion... crew required, any additional lifesaving or safety equipment required, the route for which the permit... applicable minimum safety standards when issuing an excursion permit. In particular, a vessel that is being...

40 CFR 63.1438 - Parameter monitoring levels and excursions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... required to submit Periodic Reports semiannually or quarterly. The first semiannual period is the 6-month... excursions. (5) For the fifth semiannual period—two excused excursions. (6) For the sixth and all subsequent... during the entire test period. The monitoring level(s) shall be those established during from the...

40 CFR 63.1438 - Parameter monitoring levels and excursions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... required to submit Periodic Reports semiannually or quarterly. The first semiannual period is the 6-month... excursions. (5) For the fifth semiannual period—two excused excursions. (6) For the sixth and all subsequent... during the entire test period. The monitoring level(s) shall be those established during from the...

40 CFR 63.1438 - Parameter monitoring levels and excursions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... required to submit Periodic Reports semiannually or quarterly. The first semiannual period is the 6-month... excursions. (5) For the fifth semiannual period—two excused excursions. (6) For the sixth and all subsequent... during the entire test period. The monitoring level(s) shall be those established during from the...

40 CFR 63.1438 - Parameter monitoring levels and excursions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... required to submit Periodic Reports semiannually or quarterly. The first semiannual period is the 6-month... excursions. (5) For the fifth semiannual period—two excused excursions. (6) For the sixth and all subsequent... during the entire test period. The monitoring level(s) shall be those established during from the...

36 CFR 1192.177 - Ferries, excursion boats and other vessels. [Reserved

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Ferries, excursion boats and other vessels. [Reserved] 1192.177 Section 1192.177 Parks, Forests, and Public Property ARCHITECTURAL... GUIDELINES FOR TRANSPORTATION VEHICLES Other Vehicles and Systems § 1192.177 Ferries, excursion boats and...

36 CFR 1192.177 - Ferries, excursion boats and other vessels. [Reserved

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Ferries, excursion boats and other vessels. [Reserved] 1192.177 Section 1192.177 Parks, Forests, and Public Property ARCHITECTURAL... GUIDELINES FOR TRANSPORTATION VEHICLES Other Vehicles and Systems § 1192.177 Ferries, excursion boats and...

36 CFR 1192.177 - Ferries, excursion boats and other vessels. [Reserved

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Ferries, excursion boats and other vessels. [Reserved] 1192.177 Section 1192.177 Parks, Forests, and Public Property ARCHITECTURAL... GUIDELINES FOR TRANSPORTATION VEHICLES Other Vehicles and Systems § 1192.177 Ferries, excursion boats and...

36 CFR 1192.177 - Ferries, excursion boats and other vessels. [Reserved

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Ferries, excursion boats and other vessels. [Reserved] 1192.177 Section 1192.177 Parks, Forests, and Public Property ARCHITECTURAL... GUIDELINES FOR TRANSPORTATION VEHICLES Other Vehicles and Systems § 1192.177 Ferries, excursion boats and...

Free gracilis transfer for smile in children: the Massachusetts Eye and Ear Infirmary Experience in excursion and quality-of-life changes.

PubMed

Hadlock, Tessa A; Malo, Juan S; Cheney, Mack L; Henstrom, Douglas K

2011-01-01

Free muscle transfer for facial reanimation has become the standard of care in recent decades and is now the cornerstone intervention for dynamic smile reanimation. We sought to quantify smile excursion and quality-of-life (QOL) changes in our pediatric free gracilis recipients following reanimation. We quantified gracilis muscle excursion in 17 pediatric patients undergoing 19 consecutive pediatric free gracilis transplantation operations, using our validated SMILE program, as an objective measure of functional outcome. These were compared against excursion measured the same way in a cohort of 17 adults with 19 free gracilis operations. In addition, we prospectively evaluated QOL outcomes in these children using the Facial Clinimetric Evaluation (FaCE) instrument. The mean gracilis excursion in our pediatric free gracilis recipients was 8.8 mm ± 5.0 mm, which matched adult results, but with fewer complete failures of less than 2-mm excursion, with 2 (11%) and 4 (21%), respectively. Quality-of-life measures indicated statistically significant improvements following dynamic smile reanimation (P = .01). Dynamic facial reanimation using free gracilis transfer in children has an acceptable success rate, yields improved commissure excursion, and improves QOL in the pediatric population. It should be considered first-line therapy for children with lack of a meaningful smile secondary to facial paralysis.

The Blake geomagnetic excursion recorded in a radiometrically dated speleothem

NASA Astrophysics Data System (ADS)

Osete, María-Luisa; Martín-Chivelet, Javier; Rossi, Carlos; Edwards, R. Lawrence; Egli, Ramon; Muñoz-García, M. Belén; Wang, Xianfeng; Pavón-Carrasco, F. Javier; Heller, Friedrich

2012-11-01

One of the most important developments in geomagnetism has been the recognition of polarity excursions of the Earth's magnetic field. Accurate timing of the excursions is a key point for understanding the geodynamo process and for magnetostratigraphic correlation. One of the best-known excursions is the Blake geomagnetic episode, which occurred during marine isotope stage MIS 5, but its morphology and age remain controversial. Here we show, for the first time, the Blake excursion recorded in a stalagmite which was dated using the uranium-series disequilibrium techniques. The characteristic remanent magnetisation is carried by fine-grained magnetite. The event is documented by two reversed intervals (B1 and B2). The age of the event is estimated to be between 116.5±0.7 kyr BP and 112.0±1.9 kyr BP, slightly younger (∼3-4 kyr) than recent estimations from sedimentary records dated by astronomical tuning. Low values of relative palaeointensity during the Blake episode are estimated, but a relative maximum in the palaeofield intensity coeval with the complete reversal during the B2 interval was observed. Duration of the Blake geomagnetic excursion is 4.5 kyr, two times lower than single excursions and slightly higher than the estimated diffusion time for the inner core (∼3 kyr).

An Evaluation of the British Columbia Asthma Monitoring System (BCAMS) and PM2.5 Exposure Metrics during the 2014 Forest Fire Season

PubMed Central

McLean, Kathleen E.; Yao, Jiayun; Henderson, Sarah B.

2015-01-01

The British Columbia Asthma Monitoring System (BCAMS) tracks forest fire smoke exposure and asthma-related health outcomes, identifying excursions beyond expected daily counts. Weekly reports during the wildfire season support public health and emergency management decision-making. We evaluated BCAMS by identifying excursions for asthma-related physician visits and dispensations of the reliever medication salbutamol sulfate and examining their corresponding smoke exposures. A disease outbreak detection algorithm identified excursions from 1 July to 31 August 2014. Measured, modeled, and forecasted concentrations of fine particulate matter (PM2.5) were used to assess exposure. We assigned PM2.5 levels to excursions by choosing the highest value within a seven day window centred on the excursion day. Smoky days were defined as those with PM2.5 levels ≥ 25 µg/m3. Most excursions (57%–71%) were assigned measured or modeled PM2.5 concentrations of 10 µg/m3 or higher. Of the smoky days, 55.8% and 69.8% were associated with at least one excursion for physician visits and salbutamol dispensations, respectively. BCAMS alerted most often when measures of smoke exposure were relatively high. Better performance might be realized by combining asthma-related outcome metrics in a bivariate model. PMID:26075727

Atmospheric Carbon Dioxide and its Relation to Carbon Cycle Perturbations During Ocean Anoxic Event 1d: A High Resolution Record From Dispersed Plant Cuticle

NASA Astrophysics Data System (ADS)

Richey, J. D.; Upchurch, G. R.; Joeckel, R.; Smith, J. J.; Ludvigson, G. A.; Lomax, B. H.

2013-12-01

Past geological greenhouse intervals are associated with Ocean Anoxic Events (OAEs), which result from an increase in marine primary productivity and/or an increase in the preservation of organic matter. The end point is widespread black shale deposition combined with a long-term atmospheric positive δ13C excursion and an increase in the burial of 12C. Some OAEs show a negative δ13C excursion preceding the positive excursion, indicating a perturbation in the global carbon cycle prior to the initiation of these events. The Rose Creek (RCP) locality, southeastern Nebraska, is the only known terrestrial section that preserves OAE1d (Cretaceous, Albian-Cenomanian Boundary) and has abundant charcoal and plant cuticle. These features allow for a combined carbon isotope and stomatal index (SI) analysis to determine both changes in the cycling between carbon pools (C isotope analysis) and changes in paleo-CO2 via changes in SI. Preliminary (and ongoing) SI data analysis using dispersed cuticle of Pandemophyllum kvacekii (an extinct Laurel) collected at 30 cm intervals indicate changes in SI consistent with changes in CO2. Fitting our samples to a published RCP δ13C profile, pre-excursion CO2 concentrations are high. CO2 decreases to lower concentrations in the basal 1.2 m of the RCP section, where δ13Cbulk shows a negative excursion and δ13Ccharcoal remains at pre-excursion values. CO2 concentrations become higher toward the top of the negative δ13C excursion, where δ13Cbulk and δ13Ccharcoal are at their most negative values, and drop as the negative carbon excursion terminates. Using published transfer functions, we estimate that pre-excursion CO2 concentrations were a maximum of 900 ppm. In the basal 1.2 m of RCP, CO2 drops to a maximum of 480 ppm, and rises to a maximum of 710 ppm near the top of the negative excursion. As δ13C values rise towards pre-excursion values, CO2 declines to a maximum of 400 ppm. The trend in SI is comparable to the trend in δ13Ccharcoal and follows recognized patterns, while SI shows partial divergence from δ13Cbulk. These data, while preliminary, highlight the importance of considering isotope substrate when investigating carbon cycle perturbations.

46 CFR 72.25-15 - Passenger accommodations for excursion boats, ferryboats, and passenger barges.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 3 2012-10-01 2012-10-01 false Passenger accommodations for excursion boats, ferryboats, and passenger barges. 72.25-15 Section 72.25-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... accommodations for excursion boats, ferryboats, and passenger barges. (a) Except as specifically excluded by this...

36 CFR § 1192.177 - Ferries, excursion boats and other vessels. [Reserved

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Ferries, excursion boats and other vessels. [Reserved] § 1192.177 Section § 1192.177 Parks, Forests, and Public Property... GUIDELINES FOR TRANSPORTATION VEHICLES Other Vehicles and Systems § 1192.177 Ferries, excursion boats and...

46 CFR 72.25-15 - Passenger accommodations for excursion boats, ferryboats, and passenger barges.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 3 2013-10-01 2013-10-01 false Passenger accommodations for excursion boats, ferryboats, and passenger barges. 72.25-15 Section 72.25-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... accommodations for excursion boats, ferryboats, and passenger barges. (a) Except as specifically excluded by this...

46 CFR 72.25-15 - Passenger accommodations for excursion boats, ferryboats, and passenger barges.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 3 2010-10-01 2010-10-01 false Passenger accommodations for excursion boats, ferryboats, and passenger barges. 72.25-15 Section 72.25-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... accommodations for excursion boats, ferryboats, and passenger barges. (a) Except as specifically excluded by this...

46 CFR 72.25-15 - Passenger accommodations for excursion boats, ferryboats, and passenger barges.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 3 2014-10-01 2014-10-01 false Passenger accommodations for excursion boats, ferryboats, and passenger barges. 72.25-15 Section 72.25-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... accommodations for excursion boats, ferryboats, and passenger barges. (a) Except as specifically excluded by this...

46 CFR 72.25-15 - Passenger accommodations for excursion boats, ferryboats, and passenger barges.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 3 2011-10-01 2011-10-01 false Passenger accommodations for excursion boats, ferryboats, and passenger barges. 72.25-15 Section 72.25-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... accommodations for excursion boats, ferryboats, and passenger barges. (a) Except as specifically excluded by this...

Cruising through Research: Library Skills for Young Adults.

ERIC Educational Resources Information Center

Volkman, John D.

This book presents an approach for school librarians to use to introduce basic research tools to students in grades 7-12. Twelve "Excursions" (i.e., library research projects) are described. Excursions 1 and 2 provide an introduction to reference books, and Excursions 3 and 4 explore note-taking and basic organization of research papers. The…

ODP Site 1063 (Bermuda Rise) revisited: Oxygen isotopes, excursions and paleointensity in the Brunhes Chron

NASA Astrophysics Data System (ADS)

Channell, J. E. T.; Hodell, D. A.; Curtis, J. H.

2012-02-01

An age model for the Brunhes Chron of Ocean Drilling Program (ODP) Site 1063 (Bermuda Rise) is constructed by tandem correlation of oxygen isotope and relative paleointensity data to calibrated reference templates. Four intervals in the Brunhes Chron where paleomagnetic inclinations are negative for both u-channel samples and discrete samples are correlated to the following magnetic excursions with Site 1063 ages in brackets: Laschamp (41 ka), Blake (116 ka), Iceland Basin (190 ka), Pringle Falls (239 ka). These ages are consistent with current age estimates for three of these excursions, but not for "Pringle Falls" which has an apparent age older than a recently published estimate by ˜28 kyr. For each of these excursions (termed Category 1 excursions), virtual geomagnetic poles (VGPs) reach high southerly latitudes implying paired polarity reversals of the Earth's main dipole field, that apparently occurred in a brief time span (<2 kyr in each case), several times shorter than the apparent duration of regular polarity transitions. In addition, several intervals of low paleomagnetic inclination (low and negative in one case) are observed both in u-channel and discrete samples at ˜318 ka (MIS 9), ˜412 ka (MIS 11) and in the 500-600 ka interval (MIS 14-15). These "Category 2" excursions may constitute inadequately recorded (Category 1) excursions, or high amplitude secular variation.

Effects of Visual Display on Joint Excursions Used to Play Virtual Dodgeball

PubMed Central

France, Christopher R; Applegate, Megan E; Leitkam, Samuel T; Pidcoe, Peter E; Walkowski, Stevan

2016-01-01

Background Virtual reality (VR) interventions hold great potential for rehabilitation as commercial systems are becoming more affordable and can be easily applied to both clinical and home settings. Objective In this study, we sought to determine how differences in the VR display type can influence motor behavior, cognitive load, and participant engagement. Methods Movement patterns of 17 healthy young adults (8 female, 9 male) were examined during games of Virtual Dodgeball presented on a three-dimensional television (3DTV) and a head-mounted display (HMD). The participant’s avatar was presented from a third-person perspective on a 3DTV and from a first-person perspective on an HMD. Results Examination of motor behavior revealed significantly greater excursions of the knee (P=.003), hip (P<.001), spine (P<.001), shoulder (P=.001), and elbow (P=.026) during HMD versus 3DTV gameplay, resulting in significant differences in forward (P=.003) and downward (P<.001) displacement of the whole-body center of mass. Analyses of cognitive load and engagement revealed that relative to 3DTV, participants indicated that HMD gameplay resulted in greater satisfaction with overall performance and was less frustrating (P<.001). There were no significant differences noted for mental demand. Conclusions Differences in visual display type and participant perspective influence how participants perform in Virtual Dodgeball. Because VR use within rehabilitation settings is often designed to help restore movement following orthopedic or neurologic injury, these findings provide an important caveat regarding the need to consider the potential influence of presentation format and perspective on motor behavior. PMID:27634561

A benchtop biorobotic platform for in vitro observation of muscle-tendon dynamics with parallel mechanical assistance from an elastic exoskeleton.

PubMed

Robertson, Benjamin D; Vadakkeveedu, Siddarth; Sawicki, Gregory S

2017-05-24

We present a novel biorobotic framework comprised of a biological muscle-tendon unit (MTU) mechanically coupled to a feedback controlled robotic environment simulation that mimics in vivo inertial/gravitational loading and mechanical assistance from a parallel elastic exoskeleton. Using this system, we applied select combinations of biological muscle activation (modulated with rate-coded direct neural stimulation) and parallel elastic assistance (applied via closed-loop mechanical environment simulation) hypothesized to mimic human behavior based on previously published modeling studies. These conditions resulted in constant system-level force-length dynamics (i.e., stiffness), reduced biological loads, increased muscle excursion, and constant muscle average positive power output-all consistent with laboratory experiments on intact humans during exoskeleton assisted hopping. Mechanical assistance led to reduced estimated metabolic cost and MTU apparent efficiency, but increased apparent efficiency for the MTU+Exo system as a whole. Findings from this study suggest that the increased natural resonant frequency of the artificially stiffened MTU+Exo system, along with invariant movement frequencies, may underlie observed limits on the benefits of exoskeleton assistance. Our novel approach demonstrates that it is possible to capture the salient features of human locomotion with exoskeleton assistance in an isolated muscle-tendon preparation, and introduces a powerful new tool for detailed, direct examination of how assistive devices affect muscle-level neuromechanics and energetics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Deciphering the impact of diagenesis overprint on negative δ13C excursions using rock magnetism: Case study of Ediacaran carbonates, Yangjiaping section, South China

NASA Astrophysics Data System (ADS)

Macouin, Mélina; Ader, Magali; Moreau, Marie-Gabrielle; Poitou, Charles; Yang, Zhenyu; Sun, Zhimming

2012-10-01

Rock magnetism is used here to investigate the genesis of one of the puzzling negative carbon isotopic excursions of the Neoproterozoic in the Yangtze platform (South China). A detailed characterization of the magnetic mineralogy, which includes low-temperature and high-field magnetometry and classical magnetic measurement (ARM, IRM, susceptibility), was therefore performed along upper Doushantuo and lower Dengying Formations outcropping in the Yangjiaping section. The derived magnetic parameters show variations that can be interpreted as variations in magnetic grains size and in oxide contents. They show that the magnetic content is significantly reduced in samples presenting negative δ13Ccalcite values. We interpret this as a result of magnetite dissolution and secondary carbonate precipitation during early diagenesis bacterial sulfate reduction. Combined with C and O isotopic data, paleomagnetic techniques thus show that the upper Doushantuo-lower Dengying negative excursion of the Yangjiaping section is largely due to diagenesis, although the preservation of a genuine δ13C excursion of lower magnitude from +7‰ down to 0‰, instead of down to -9‰ as usually considered, cannot be ruled out. A corrected δ13Ccarbonate chemostratigraphic curve is therefore proposed. The unambiguous identification of a strong diagenetic component for this excursion casts doubts on the primary nature of other potentially time equivalent negative excursions of the Yangtze platform and thus to its correlation to negative excursions in other cratons (i.e. Shuram excursion). More generally, this study illustrates the potential of magnetic mineralogy characterization, a low cost, time efficient and non-destructive technique, as screening tool for diagenetic overprints of δ13C and δ18O.

Use of an Anatomical Scalar to Control for Sex-Based Size Differences in Measures of Hyoid Excursion during Swallowing

ERIC Educational Resources Information Center

Molfenter, Sonja M.; Steele, Catriona M.

2014-01-01

Purpose: Traditional methods for measuring hyoid excursion from dynamic videofluoroscopy recordings involve calculating changes in position in absolute units (mm). This method shows a high degree of variability across studies but agreement that greater hyoid excursion occurs inmen than in women. Given that men are typically taller than women, the…

Relation of Phanerozoic stable isotope excursions to climate, bacterial metabolism, and major extinctions

PubMed Central

Stanley, Steven M.

2010-01-01

Conspicuous global stable carbon isotope excursions that are recorded in marine sedimentary rocks of Phanerozoic age and were associated with major extinctions have generally paralleled global stable oxygen isotope excursions. All of these phenomena are therefore likely to share a common origin through global climate change. Exceptional patterns for carbon isotope excursions resulted from massive carbon burial during warm intervals of widespread marine anoxic conditions. The many carbon isotope excursions that parallel those for oxygen isotopes can to a large degree be accounted for by the Q10 pattern of respiration for bacteria: As temperature changed along continental margins, where ∼90% of marine carbon burial occurs today, rates of remineralization of isotopically light carbon must have changed exponentially. This would have reduced organic carbon burial during global warming and increased it during global cooling. Also contributing to the δ13C excursions have been release and uptake of methane by clathrates, the positive correlation between temperature and degree of fractionation of carbon isotopes by phytoplankton at temperatures below ∼15°, and increased phytoplankton productivity during “icehouse” conditions. The Q10 pattern for bacteria and climate-related changes in clathrate volume represent positive feedbacks for climate change. PMID:21041682

Highway driving safety the day after using sleep medication: the direction of lapses and excursions out-of-lane in drowsy drivers.

PubMed

Verster, Joris C; Mooren, Loes; Bervoets, Adriana C; Roth, Thomas

2017-10-24

The primary outcome measure of the on-road driving test is the Standard Deviation of Lateral Position. However, other outcome measures, such as lapses and excursions out-of-lane, also need to be considered as they may be related to crash risk. The aim of this study was to determine the direction of lapses and excursions out-of-lane (i.e. towards/into the adjacent traffic lane or towards/into the road shoulder). In total, data from 240 driving tests were re-analysed, and 628 lapses and 401 excursions out-of-lane were identified. The analyses revealed that lapses were made equally frequently over left (49.4%) and over right (43.3%). In contrast, excursions out-of-lane were almost exclusively directed over right into the (safer) road shoulder (97.3%). These findings suggest that drivers are unaware of having lapses, whereas excursions out-of-lane are events where the driver is aware of loss of vehicle control. © 2017 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.

Off-design temperature effects on nuclear fuel pins for an advanced space-power-reactor concept

NASA Technical Reports Server (NTRS)

Bowles, K. J.

1974-01-01

An exploratory out-of-reactor investigation was made of the effects of short-time temperature excursions above the nominal operating temperature of 990 C on the compatibility of advanced nuclear space-power reactor fuel pin materials. This information is required for formulating a reliable reactor safety analysis and designing an emergency core cooling system. Simulated uranium mononitride (UN) fuel pins, clad with tungsten-lined T-111 (Ta-8W-2Hf) showed no compatibility problems after heating for 8 hours at 2400 C. At 2520 C and above, reactions occurred in 1 hour or less. Under these conditions free uranium formed, redistributed, and attacked the cladding.

Military Power in Operations Other Than War

DTIC Science & Technology

1994-06-03

of a Shiite state in the south, a Kurdish state in the north, and a Sunni Arab Mesopotamian state in the center, all at war with each other. While...made an excursion into a culture as different from America’s as an African Negro’s is different from that of an Eskimo. No man could hope to span the ...differences in American and Vietnamese culture and heritage in the short time of his appointment in our land. How could I explain . . that while an

Modeling the Impact of Forest and Peat Fires on Carbon-Isotopic Compositions of Cretaceous Atmosphere and Vegetation

NASA Astrophysics Data System (ADS)

Finkelstein, D. B.; Pratt, L. M.

2004-12-01

Prevalence of wildfires or peat fires associated with seasonally dry conditions in the Cretaceous is supported by recent studies documenting the widespread presence of pyrolytic polycyclic aromatic hydrocarbons and fusinite. Potential roles of CO2 emissions from fire have been overlooked in many discussions of Cretaceous carbon-isotope excursions (excluding K-P boundary discussions). Enhanced atmospheric CO2 levels could increase fire frequency through elevated lightning activity. When biomass or peat is combusted, emissions of CO2 are more negative than atmospheric CO2. Five reservoirs (atmosphere, vegetation, soil, and shallow and deep oceans), and five fluxes (productivity, respiration, litter fall, atmosphere-ocean exchange, and surface-deep ocean exchange) were modeled as a closed system. The size of the Cretaceous peat reservoir was estimated by compilation of published early Cretaceous coal resources. Initial pCO2 was assumed to be 2x pre-industrial atmospheric levels (P.A.L.). Critical variables in the model are burning efficiency and post-fire growth rates. Assuming 1% of standing terrestrial biomass is consumed by wildfires each year for ten years (without combustion of peat), an increase of atmospheric CO2 (from 2.0 to 2.2x P.A.L.) and a negative carbon isotope excursion (-1.2 ‰ ) are recorded by both atmosphere and new growth. Net primary productivity linked to the residence time of the vegetation and soil reservoirs results in a negative isotope shift followed by a broad positive isotope excursion. Decreasing the rate of re-growth dampens this trailing positive shift and increases the duration of the excursion. Post-fire pCO2 and new growth returned to initial values after 72 years. Both negative and positive isotope excursions are recorded in the model in surface ocean waters. Exchange of CO2 with the surface- and deep-ocean dampens the isotopic shift of the atmosphere. Excursions are first recorded in the atmosphere (and new growth), followed by the ocean, vegetation, and soil reservoirs. Ten to twenty five-year cycles of drought and fire are not recorded as individual excursions in the soil reservoir as the rate of transfer between the vegetation and soil reservoirs homogenizes the signal. A wildfire-modeled excursion does not propagate a geologically significant excursion through time. Combustion of a peat reservoir is necessary to drive and validate a geologically and isotopically significant excursion. Assuming 0.5% of the standing early Cretaceous peat reservoir is consumed by fire for each year for ten years coupled with the earlier scenario, the atmospheric CO2 increases from 2.0 to 3.1x P.A.L., atmosphere, vegetation, and the surface ocean record a negative carbon isotope excursion of -5.1 ‰ , -3.8 ‰ and -1.8 ‰ respectively, with a duration of 741 years. Increasing the size of the vegetation reservoir translates the excursions from the centennial to millennial scale. For example, doubling the vegetation reservoir (from 1.4 to 2.8E+16 gC) for a 25 year global peat conflagration (0.5% combusted each year) results in a CO2 increase from 2.0 to 4.0x P.A.L., and the atmosphere, vegetation, and the surface ocean reservoirs with a negative carbon isotope excursion of -5.7 ‰ , -8.7 ‰ and -2.3 ‰ respectively. Addition of carbonaceous aerosols (black carbon and polycyclic aromatic hydrocarbons) to pelagic marine sediments could potentially serve as a high-resolution record of ancient fires and firmly tie isotopic shifts to paleofires.

Assessment of vertical excursions and open-sea psychological performance at depths to 250 fsw.

PubMed

Miller, J W; Bachrach, A J; Walsh, J M

1976-12-01

A series of 10 two-man descending vertical excursion dives was carried out in the open sea from an ocean-floor habitat off the coast of Puerto Rico by four aquanauts saturated on a normoxic-nitrogen breathing mixture at a depth of 106 fsw. The purpose of these dives was two-fold: to validate laboratory findings with respect to decompression schedules and to determine whether such excursions would produce evidence of adaptation to nitrogen narcosis. For the latter, tests designed to measure time estimation, short-term memory, and auditory vigilance were used. The validation of experimental excursion tables was carried out without incidence of decompression sickness. Although no signs of nitrogen narcosis were noted during testing, all subjects made significantly longer time estimates in the habitat and during the excursions than on the surface. Variability and incomplete data prevented a statistical analysis of the short-term memory results, and the auditory vigilance proved unusable in the water.

Human risk factors associated with pilots in runway excursions.

PubMed

Chang, Yu-Hern; Yang, Hui-Hua; Hsiao, Yu-Jung

2016-09-01

A breakdown analysis of civil aviation accidents worldwide indicates that the occurrence of runway excursions represents the largest portion among all aviation occurrence categories. This study examines the human risk factors associated with pilots in runway excursions, by applying a SHELLO model to categorize the human risk factors and to evaluate the importance based on the opinions of 145 airline pilots. This study integrates aviation management level expert opinions on relative weighting and improvement-achievability in order to develop four kinds of priority risk management strategies for airline pilots to reduce runway excursions. The empirical study based on experts' evaluation suggests that the most important dimension is the liveware/pilot's core ability. From the perspective of front-line pilots, the most important risk factors are the environment, wet/containment runways, and weather issues like rain/thunderstorms. Finally, this study develops practical strategies for helping management authorities to improve major operational and managerial weaknesses so as to reduce the human risks related to runway excursions. Copyright © 2016 Elsevier Ltd. All rights reserved.

The metatarsosesamoid joint: an in vitro 3D quantitative assessment.

PubMed

Jamal, Bilal; Pillai, Anand; Fogg, Quentin; Kumar, Senthil

2015-03-01

The anatomy of the first metatarsophalangeal (MTP) joint, particularly the metatarsosesamoid articulation, remains poorly understood. Our goal was to quantitatively define the excursion of the sesamoids. Seven cadavers were dissected to assess the articulating surfaces throughout a normal range of motion. The dissections were digitally reconstructed in various positions using a MicroScribe. For first MTP joint, excursion averaged 14.7mm for the tibial sesamoid in the sagittal plane and 7.5mm for the fibular sesamoid. The sesamoids also moved medially to laterally when the joint was dorsiflexed. For the maximally dorsiflexed joint, excursion averaged 2.8mm for the tibial sesamoid and 3.5mm for the fibular sesamoid. Hallucal sesamoids appear to have differential tracking: the tibial sesamoid has greater longitudinal excursion; the fibular sesamoid has greater lateral excursion. The anatomical data will interest those involved with the design of an effective hallux arthroplasty. Copyright © 2014 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

Head Excursion of Restrained Human Volunteers and Hybrid III Dummies in Steady State Rollover Tests

PubMed Central

Moffatt, Edward; Hare, Barry; Hughes, Raymond; Lewis, Lance; Iiyama, Hiroshi; Curzon, Anne; Cooper, Eddie

2003-01-01

Seatbelts provide substantial benefits in rollover crashes, yet occupants still receive head and neck injuries from contacting the vehicle roof interior when the roof exterior strikes the ground. Prior research has evaluated rollover restraint performance utilizing anthropomorphic test devices (dummies), but little dynamic testing has been done with human volunteers to learn how they move during rollovers. In this study, the vertical excursion of the head of restrained dummies and human subjects was measured in a vehicle being rotated about its longitudinal roll axis at roll rates from 180-to-360 deg/sec and under static inversion conditions. The vehicle’s restraint design was the commonly used 3-point seatbelt with continuous loop webbing and a sliding latch plate. This paper presents an analysis of the observed occupant motion and provides a comparison of dummy and human motion under similar test conditions. Thirty-five tests (eighteen static and seventeen dynamic) were completed using two different sizes of dummies and human subjects in both near and far-side roll directions. The research indicates that far-side rollovers cause the restrained test subjects to have greater head excursion than near-side rollovers, and that static inversion testing underestimates head excursion for far-side occupants. Human vertical head excursion of up to 200 mm was found at a roll rate of 220 deg/sec. Humans exhibit greater variability in head excursion in comparison to dummies. Transfer of seatbelt webbing through the latch plate did not correlate directly with differences in head excursion. PMID:12941241

Record of the Late Devonian Hangenberg global positive carbon-isotope excursion in an epeiric sea setting: Carbonate production, organic-carbon burial and paleoceanography during the late Famennian

USGS Publications Warehouse

Cramer, Bradley D.; Saltzman, Matthew R.; Day, J.E.; Witzke, B.J.

2008-01-01

Latest Famennian marine carbonates from the mid-continent of North America were examined to investigate the Late Devonian (very late Famennian) Hangenberg positive carbon-isotope (??13 Ccarb) excursion. This global shift in the ?? 13C of marine waters began during the late Famennian Hangenberg Extinction Event that occurred during the Middle Siphonodella praesulcata conodont zone. The post-extinction recovery interval spans the Upper S. praesulcata Zone immediately below the Devonian-Carboniferous boundary. Positive excursions in ?? 13 Ccarb are often attributed to the widespread deposition of organic-rich black shales in epeiric sea settings. The Hangenberg ??13 Ccarb excursion documented in the Louisiana Limestone in this study shows the opposite trend, with peak ??13 Ccarb values corresponding to carbonate production in the U.S. mid-continent during the highstand phase of the very late Famennian post-glacial sea level rise. Our data indicate that the interval of widespread black shale deposition (Hangenberg Black Shale) predates the peak isotope values of the Hangenberg ??13 Ccarb excursion and that peak values of the Hangenberg excursion in Missouri are not coincident with and cannot be accounted for by high Corg burial in epeiric seas. We suggest instead that sequestration and burial of Corg in the deep oceans drove the peak interval of the ??13Ccarb excursion, as a result of a change in the site of deep water formation to low-latitude epeiric seas as the global climate shifted between cold and warm states.

A paleomagnetic record in loess-paleosol sequences since late Pleistocene in the arid Central Asia

NASA Astrophysics Data System (ADS)

Li, Guanhua; Xia, Dunsheng; Appel, Erwin; Wang, Youjun; Jia, Jia; Yang, Xiaoqiang

2018-03-01

Geomagnetic excursions during Brunhes epoch have been brought to the forefront topic in paleomagnetic study, as they provide key information about Earth's interior dynamics and could serve as another tool for stratigraphic correlation among different lithology. Loess-paleosol sequences provide good archives for decoding geomagnetic excursions. However, the detailed pattern of these excursions was not sufficiently clarified due to pedogenic influence. In this study, paleomagnetic analysis was performed in loess-paleosol sequences on the northern piedmont of the Tianshan Mountains (northwestern China). By radiocarbon and luminance dating, the loess section was chronologically constrained to mainly the last c.130 ka, a period when several distinct geomagnetic excursions were involved. The rock magnetic properties in this loess section are dominated by magnetite and maghemite in a pseudo-single-domain state. The rock magnetic properties and magnetic anisotropy indicate weakly pedogenic influence for magnetic record. The stable component of remanent magnetization derived from thermal demagnetization revealed the presence of two intervals of directional anomalies with corresponding intensity lows in the Brunhes epoch. The age control in the key layers indicates these anomalies are likely associated with the Laschamp and Blake excursions, respectively. In addition, relative paleointensity in the loess section is basically compatible with other regional and global relative paleointensity records and indicates two low-paleointensity zones, possibly corresponding to the Blake and Laschamp excursions, respectively. As a result, this study suggests that the loess section may have the potential to record short-lived excursions, which largely reflect the variation of dipole components in the global archives.

Engaging students in research learning experiences through hydrology field excursions and projects

NASA Astrophysics Data System (ADS)

Ewen, T.; Seibert, J.

2014-12-01

One of the best ways to engage students and instill enthusiasm for hydrology is to expose them to hands-on learning. A focus on hydrology field research can be used to develop context-rich and active learning, and help solidify idealized learning where students are introduced to individual processes through textbook examples, often neglecting process interactions and an appreciation for the complexity of the system. We introduced a field course where hydrological measurement techniques are used to study processes such as snow hydrology and runoff generation, while also introducing students to field research and design of their own field project. In the field projects, students design a low-budget experiment with the aim of going through the different steps of a 'real' scientific project, from formulating the research question to presenting their results. In one of the field excursions, students make discharge measurements in several alpine streams with a salt tracer to better understand the spatial characteristics of an alpine catchment, where source waters originate and how they contribute to runoff generation. Soil moisture measurements taken by students in this field excursion were used to analyze spatial soil moisture patterns in the alpine catchment and subsequently used in a publication. Another field excursion repeats a published experiment, where preferential soil flow paths are studied using a tracer and compared to previously collected data. For each field excursion, observational data collected by the students is uploaded to an online database we developed, which also allows students to retrieve data from past excursions to further analyze and compare their data. At each of the field sites, weather stations were installed and a webviewer allows access to realtime data from data loggers, allowing students to explore how processes relate to climatic conditions. With in-house film expertise, these field excursions were also filmed and short virtual excursions were produced, which we plan to use in a large introductory course, exposing students to field research at an early stage.

Coupled organic and carbonate δ13C records of the late Triassic and early Jurassic in northern Italy: implications for carbon cycling during the aftermath of the end-Triassic mass extinction

NASA Astrophysics Data System (ADS)

Bachan, A.; van de Schootbrugge, B.; Payne, J.

2011-12-01

A large protracted positive carbon isotope excursion has been observed in the lowermost Jurassic following the end-Triassic mass extinction. However, the lack of paired records from carbonate rocks (δ13Ccarb) and organic carbon (δ13Corg) and limited biostratigraphic constraints leave open the possibility that variations in δ13Ccarb and δ13Corg are not correlative and do not represent a shift in the δ13C of the global carbon pool. Consequently, the long term carbon cycle behavior following the end-Triassic mass extinction remains incompletely understood. Here we present the first extended, coupled δ13Ccarb and δ13Corg records of the uppermost Triassic and lowermost Jurassic from stratigraphic sections in the Lombardy Basin of northern Italy. The large positive excursion previously observed in the carbonates also occurs in the organics from the same samples, but with a smaller magnitude. Because few post-depositional mechanisms affect the isotopic composition of Ccarb and Corg in similar ways, the correspondence of the two curves presents strong support for a primary origin for the large positive isotopic excursion. The more muted response of the organics is consistent with variation in the fractionation between carbonates and organic carbon, mixing of contemporaneous organic matter with extrabasinal organic carbon of a constant isotopic composition, or some combination of the two. In either case, the occurrence of the positive excursion in multiple locations globally in both carbonates and organic matter is best explained by a change in the isotopic value of the global carbon reservoir. The elevated δ13C values and increased magnitude of the difference between the carbonates and organics is consistent with the predicted biogeochemical consequences of heightened pCO2. The coincidence of the extinction and carbon cycle disturbance with emplacement of the Central Atlantic Magmatic Province suggests that volatiles derived from its emplacement were the likely source of the perturbation.

A Full Vector Study of a Terrestrial Geomagnetic Record of the Porcupine Excursion (ca. 2737 ka) Recovered From a Long Volcanic Sequence at Makapuu Point, Koolau Volcano, Hawaii, USA.

NASA Astrophysics Data System (ADS)

Herrero-Bervera, E.; Jicha, B.

2017-12-01

New paleomagnetic measurements, coupled with 40Ar/39Ar dating are revolutionizing our understanding of the geodynamo by providing terrestrial lava records of the short-term behavior of the paleofield. As part of an investigation of the Koolau volcano, Oahu, and the short-term behavior of the geomagnetic field, we have sampled the exposed flows of a long volcanic section (i.e. 191-m) located on the volcano's southwest collapsed flank at a locality known as Makapuu Point. Paleomagnetic and K-Ar investigations of the Koolau Volcanic Series have revealed excursional directions for lavas ranging from 2-3 Ma. The easy access and close geographical proximity to the K-Ar dated lava flows made this newly studied 191-m thick sequence of flows an excellent candidate for detailed paleomagnetic analysis. At least 10 samples, collected from each of the successive sites, were stepwise demagnetized by both a.f. (5-100 mT) and thermal (28 to 700 °C) methods. Mean directions were obtained by p.c. analysis. All samples yielded a strong and stable ChRM vector demagnetization diagrams based on 7 or more demagnetization steps, with thermal and a.f. results differing insignificantly. k-T analysis conducted on individual lava flows indicated 50% with reversible curves. Curie points from these analyses revealed a temperature close to or equal to 150-250oC, 575°C and 620oC, indicative of Ti-poor and Ti-rich magnetite as well as titanomaghemite ranging from single domain to pseudosingle domain grain sizes. The mean directions of the base of the section sampled up to ˜14m of the section are excursional ( 10 flows). We have also conducted absolute paleointensity (PI) determinations of the excursional flows using the Thellier-Coe protocol yielding PI values as low as 19 mT and up to 88 mT within the excursional zone of the record. 40Ar/39Ar incremental heating experiments on the groundmass from at least one flow site at 9-m from sea level that yields a plateau with an age of 2.60±0.13 Ma, suggesting that the excursion corresponds to the Porcupine excursion (ca. 2737 ka) reported by Channell et al., (2016). This is the first terrestrial record of the Porcupine excursion and the age is 2-3% younger than in the reported timescale. The obtained VGPs are located over the northeastern part of Asia, close to the artic Circle and as far south as the East China Sea.

Glucose excursions and glycaemic control during Ramadan fasting in diabetic patients: insights from continuous glucose monitoring (CGM).

PubMed

Lessan, N; Hannoun, Z; Hasan, H; Barakat, M T

2015-02-01

Ramadan fasting represents a major shift in meal timing and content for practicing Muslims. This study used continuous glucose monitoring (CGM) to assess changes in markers of glycaemic excursions during Ramadan fasting to investigate the short-term safety of this practice in different groups of patients with diabetes. A total of 63 subjects (56 with diabetes, seven healthy volunteers; 39 male, 24 female) had CGM performed during, before and after Ramadan fasting. Mean CGM curves were constructed for each group for these periods that were then used to calculate indicators of glucose control and excursions. Post hoc data analyses included comparisons of different medication categories (metformin/no medication, gliptin, sulphonylurea and insulin). Medication changes during Ramadan followed American Diabetes Association guidelines. Among patients with diabetes, there was a significant difference in mean CGM curve during Ramadan, with a slow fall during fasting hours followed by a rapid rise in glucose level after the sunset meal (iftar). The magnitude of this excursion was greatest in the insulin-treated group, followed by the sulphonylurea-treated group. Markers of control deteriorated in a small number (n=3) of patients. Overall, whether fasting or non-fasting, subjects showed no statistically significant changes in mean interstitial glucose (IG), mean amplitude of glycaemic excursion (MAGE), high and low blood glucose indices (HBGI/LBGI), and number of glucose excursions and rate of hypoglycaemia. The main change in glycaemic control with Ramadan fasting in patients with diabetes is in the pattern of excursions. Ramadan fasting caused neither overall deterioration nor improvement in the majority of patients with good baseline glucose control. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Comparison of Diaphragmatic Breathing Exercise, Volume and Flow Incentive Spirometry, on Diaphragm Excursion and Pulmonary Function in Patients Undergoing Laparoscopic Surgery: A Randomized Controlled Trial

PubMed Central

Anand, R.

2016-01-01

Objective. To evaluate the effects of diaphragmatic breathing exercises and flow and volume-oriented incentive spirometry on pulmonary function and diaphragm excursion in patients undergoing laparoscopic abdominal surgery. Methodology. We selected 260 patients posted for laparoscopic abdominal surgery and they were block randomization as follows: 65 patients performed diaphragmatic breathing exercises, 65 patients performed flow incentive spirometry, 65 patients performed volume incentive spirometry, and 65 patients participated as a control group. All of them underwent evaluation of pulmonary function with measurement of Forced Vital Capacity (FVC), Forced Expiratory Volume in the first second (FEV1), Peak Expiratory Flow Rate (PEFR), and diaphragm excursion measurement by ultrasonography before the operation and on the first and second postoperative days. With the level of significance set at p < 0.05. Results. Pulmonary function and diaphragm excursion showed a significant decrease on the first postoperative day in all four groups (p < 0.001) but was evident more in the control group than in the experimental groups. On the second postoperative day pulmonary function (Forced Vital Capacity) and diaphragm excursion were found to be better preserved in volume incentive spirometry and diaphragmatic breathing exercise group than in the flow incentive spirometry group and the control group. Pulmonary function (Forced Vital Capacity) and diaphragm excursion showed statistically significant differences between volume incentive spirometry and diaphragmatic breathing exercise group (p < 0.05) as compared to that flow incentive spirometry group and the control group. Conclusion. Volume incentive spirometry and diaphragmatic breathing exercise can be recommended as an intervention for all patients pre- and postoperatively, over flow-oriented incentive spirometry for the generation and sustenance of pulmonary function and diaphragm excursion in the management of laparoscopic abdominal surgery. PMID:27525116

Comparison of Diaphragmatic Breathing Exercise, Volume and Flow Incentive Spirometry, on Diaphragm Excursion and Pulmonary Function in Patients Undergoing Laparoscopic Surgery: A Randomized Controlled Trial.

PubMed

Alaparthi, Gopala Krishna; Augustine, Alfred Joseph; Anand, R; Mahale, Ajith

2016-01-01

Objective. To evaluate the effects of diaphragmatic breathing exercises and flow and volume-oriented incentive spirometry on pulmonary function and diaphragm excursion in patients undergoing laparoscopic abdominal surgery. Methodology. We selected 260 patients posted for laparoscopic abdominal surgery and they were block randomization as follows: 65 patients performed diaphragmatic breathing exercises, 65 patients performed flow incentive spirometry, 65 patients performed volume incentive spirometry, and 65 patients participated as a control group. All of them underwent evaluation of pulmonary function with measurement of Forced Vital Capacity (FVC), Forced Expiratory Volume in the first second (FEV1), Peak Expiratory Flow Rate (PEFR), and diaphragm excursion measurement by ultrasonography before the operation and on the first and second postoperative days. With the level of significance set at p < 0.05. Results. Pulmonary function and diaphragm excursion showed a significant decrease on the first postoperative day in all four groups (p < 0.001) but was evident more in the control group than in the experimental groups. On the second postoperative day pulmonary function (Forced Vital Capacity) and diaphragm excursion were found to be better preserved in volume incentive spirometry and diaphragmatic breathing exercise group than in the flow incentive spirometry group and the control group. Pulmonary function (Forced Vital Capacity) and diaphragm excursion showed statistically significant differences between volume incentive spirometry and diaphragmatic breathing exercise group (p < 0.05) as compared to that flow incentive spirometry group and the control group. Conclusion. Volume incentive spirometry and diaphragmatic breathing exercise can be recommended as an intervention for all patients pre- and postoperatively, over flow-oriented incentive spirometry for the generation and sustenance of pulmonary function and diaphragm excursion in the management of laparoscopic abdominal surgery.

A carbon isotopic and sedimentological record of the latest Devonian (Famennian) from the Western U.S. and Germany

USGS Publications Warehouse

Myrow, P.M.; Strauss, J.V.; Creveling, J.R.; Sicard, K.R.; Ripperdan, R.; Sandberg, C.A.; Hartenfels, S.

2011-01-01

New carbon isotopic data from upper Famennian deposits in the western United States reveal two previously unrecognized major positive isotopic excursions. The first is an abrupt ~. 3??? positive excursion, herein referred to as ALFIE (A Late Famennian Isotopic Excursion), recorded in two sections of the Pinyon Peak Limestone of north-central Utah. Integration of detailed chemostratigraphic and biostratigraphic data suggests that ALFIE is the Laurentian record of the Dasberg Event, which has been linked to transgression in Europe and Morocco. Sedimentological data from the Chaffee Group of western Colorado also record transgression at a similar biostratigraphic position, with a shift from restricted to open-marine lithofacies. ALFIE is not evident in chemostratigraphic data from age-equivalent strata in Germany studied herein and in southern Europe, either because it is a uniquely North American phenomenon, or because the German sections are too condensed relative to those in Laurentia. A second positive carbon isotopic excursion from the upper Chaffee Group of Colorado is recorded in transgressive strata deposited directly above a previously unrecognized paleokarst interval. The age of this excursion, and the duration of the associated paleokarst hiatus, are not well constrained, although the events occurred sometime after the Late Famennian Middle expansa Zone. The high positive values recorded in this excursion are consistent with those associated with the youngest Famennian Middle to Late praesulcata Hangenberg Isotopic Excursion in Europe, the isotopic expression of the Hangenberg Event, which included mass extinction, widespread black shale deposition, and a glacio-eustatic fall and rise. If correct, this would considerably revise the age of the Upper Chaffee Group strata of western Colorado. ?? 2011 Elsevier B.V.

Exploring the Angstrom Excursion of Au Nanoparticles Excited away from a Metal Surface by an Impulsive Acoustic Perturbation.

PubMed

Kim, Ji-Wan; Kovalenko, Oleksandr; Liu, Yu; Bigot, Jean-Yves

2016-12-27

We report the anharmonic angstrom dynamics of self-assembled Au nanoparticles (Au:NPs) away from a nickel surface on top of which they are coupled by their near-field interaction. The deformation and the oscillatory excursion away from the surface are induced by picosecond acoustic pulses and probed at the surface plasmon resonance with femtosecond laser pulses. The overall dynamics are due to an efficient transfer of translational momentum from the Ni surface to the Au:NPs, therefore avoiding usual thermal effects and energy redistribution among the electronic states. Two modes are clearly revealed by the oscillatory shift of the Au:NPs surface plasmon resonance-the quadrupole deformation mode due to the transient ellipsoid shape and the excursion mode when the Au:NPs bounce away from the surface. We find that, contrary to the quadrupole mode, the excursion mode is sensitive to the distance between Au:NPs and Ni. Importantly, the excursion dynamics display a nonsinusoidal motion that cannot be explained by a standard harmonic potential model. A detailed modeling of the dynamics using a Hamaker-type Lennard-Jones potential between two media is performed, showing that each Au:NPs coherently evolves in a nearly one-dimensional anharmonic potential with a total excursion of ∼1 Å. This excursion induces a shift of the surface plasmon resonance detectable because of the strong near-field interaction. This general method of observing the spatiotemporal dynamics with angstrom and picosecond resolutions can be directly transposed to many nanostructures or biosystems to reveal the interaction and contact mechanism with their surrounding medium while remaining in their fundamental electronic states.

Duration of and decoupling between carbon isotope excursions during the end-Triassic mass extinction and Central Atlantic Magmatic Province emplacement

NASA Astrophysics Data System (ADS)

Yager, Joyce A.; West, A. Joshua; Corsetti, Frank A.; Berelson, William M.; Rollins, Nick E.; Rosas, Silvia; Bottjer, David J.

2017-09-01

Changes in δ13Ccarb and δ13Corg from marine strata occur globally in association with the end-Triassic mass extinction and the emplacement of the Central Atlantic Magmatic Province (CAMP) during the break up of Pangea. As is typical in deep time, the timing and duration of these isotopic excursions has remained elusive, hampering attempts to link carbon cycle perturbations to specific processes. Here, we report δ13Ccarb and δ13Corg from Late Triassic and Early Jurassic strata near Levanto, Peru, where intercalated dated ash beds permit temporal calibration of the carbon isotope record. Both δ13Ccarb and δ13Corg exhibit a broad positive excursion through the latest Triassic into the earliest Jurassic. The first order positive excursion in δ13Corg is interrupted by a negative shift noted in many sections around the world coincident with the extinction horizon. Our data indicate that the negative excursion lasts 85 ± 25 kyrs, longer than inferred by previous studies based on cyclostratigraphy. A 260 ± 80 kyr positive δ13Corg shift follows, during which the first Jurassic ammonites appear. The overall excursion culminates in a return to pre-perturbation carbon isotopic values over the next 1090 ± 70 kyrs. Via chronologic, isotopic, and biostratigraphic correlation to other successions, we find that δ13Ccarb and δ13Corg return to pre-perturbation values as CAMP volcanism ceases and in association with the recovery of pelagic and benthic biota. However, the initiation of the carbon isotope excursion at Levanto predates the well-dated CAMP sills from North America, indicating that CAMP may have started earlier than thought based on these exposures, or that the onset of carbon cycle perturbations was not related to CAMP.

Fission yield and criticality excursion code

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

Blanchard, A.

2000-06-30

The ANSI/ANS 8.3 standard allows a maximum yield not to exceed 2 x 10 fissions to calculate requiring the alarm system to be effective. It is common practice to use this allowance or to develop some other yield based on past criticality accident history or excursion experiments. The literature on the subject of yields discusses maximum yields larger and somewhat smaller than the ANS 8.3 permissive value. The ability to model criticality excursions and vary the various parameters to determine a credible maximum yield for operational specific cases has been available for some time but is not in common usemore » by criticality safety specialists. The topic of yields for various solution, metal, oxide powders, etc. in various geometry's and containers has been published by laboratory specialists or university staff and students for many decades but have not been available to practitioners. The need for best-estimate calculations of fission yields with a well-validated criticality excursion code has long been recognized. But no coordinated effort has been made so far to develop a generalized and well-validated excursion code for different types of systems. In this paper, the current practices to estimate fission yields are summarized along with its shortcomings for the 12-Rad zone (at SRS) and Criticality Alarm System (CAS) calculations. Finally the need for a user-friendly excursion code is reemphasized.« less

Probabilistic risk assessment of the Space Shuttle. Phase 3: A study of the potential of losing the vehicle during nominal operation. Volume 5: Auxiliary shuttle risk analyses

NASA Technical Reports Server (NTRS)

Fragola, Joseph R.; Maggio, Gaspare; Frank, Michael V.; Gerez, Luis; Mcfadden, Richard H.; Collins, Erin P.; Ballesio, Jorge; Appignani, Peter L.; Karns, James J.

1995-01-01

Volume 5 is Appendix C, Auxiliary Shuttle Risk Analyses, and contains the following reports: Probabilistic Risk Assessment of Space Shuttle Phase 1 - Space Shuttle Catastrophic Failure Frequency Final Report; Risk Analysis Applied to the Space Shuttle Main Engine - Demonstration Project for the Main Combustion Chamber Risk Assessment; An Investigation of the Risk Implications of Space Shuttle Solid Rocket Booster Chamber Pressure Excursions; Safety of the Thermal Protection System of the Space Shuttle Orbiter - Quantitative Analysis and Organizational Factors; Space Shuttle Main Propulsion Pressurization System Probabilistic Risk Assessment, Final Report; and Space Shuttle Probabilistic Risk Assessment Proof-of-Concept Study - Auxiliary Power Unit and Hydraulic Power Unit Analysis Report.

Scaphoid tuberosity excursion is minimized during a dart-throwing motion: A biomechanical study.

PubMed

Werner, Frederick W; Sutton, Levi G; Basu, Niladri; Short, Walter H; Moritomo, Hisao; St-Amand, Hugo

2016-01-01

The purpose of this study was to determine whether the excursion of the scaphoid tuberosity and therefore scaphoid motion is minimized during a dart-throwing motion. Scaphoid tuberosity excursion was studied as an indicator of scaphoid motion in 29 cadaver wrists as they were moved through wrist flexion-extension, radioulnar deviation, and a dart-throwing motion. Study results demonstrate that excursion was significantly less during the dart-throwing motion than during either wrist flexion-extension or radioulnar deviation. If the goal of early wrist motion after carpal ligament or distal radius injury and reconstruction is to minimize loading of the healing structures, a wrist motion in which scaphoid motion is minimal should reduce length changes in associated ligamentous structures. Therefore, during rehabilitation, if a patient uses a dart-throwing motion that minimizes his or her scaphoid tuberosity excursion, there should be minimal changes in ligament loading while still allowing wrist motion. Bench research, biomechanics, and cross-sectional. Not applicable. The study was laboratory based. Copyright © 2016 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

Compensation for large thorax excursions in EIT imaging.

PubMed

Schullcke, B; Krueger-Ziolek, S; Gong, B; Mueller-Lisse, U; Moeller, K

2016-09-01

Besides the application of EIT in the intensive care unit it has recently also been used in spontaneously breathing patients suffering from asthma bronchiole, cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD). In these cases large thorax excursions during deep inspiration, e.g. during lung function testing, lead to artifacts in the reconstructed images. In this paper we introduce a new approach to compensate for image artifacts resulting from excursion induced changes in boundary voltages. It is shown in a simulation study that boundary voltage change due to thorax excursion on a homogeneous model can be used to modify the measured voltages and thus reduce the impact of thorax excursion on the reconstructed images. The applicability of the method on human subjects is demonstrated utilizing a motion-tracking-system. The proposed technique leads to fewer artifacts in the reconstructed images and improves image quality without substantial increase in computational effort, making the approach suitable for real-time imaging of lung ventilation. This might help to establish EIT as a supplemental tool for lung function tests in spontaneously breathing patients to support clinicians in diagnosis and monitoring of disease progression.

Behavior and Performance Project

NASA Technical Reports Server (NTRS)

Washburn, David A.; Rumbaugh, Duane M.; Shlyk, Galina; Vassilieva, Oxana; Richardson, W. Kirk

1998-01-01

Behavior is an overt manifestation of underlying biology. As such, alterations in biological systems that result from spaceflight would be expected to evidence themselves in subtle or even pronounced changes in the behavior of that organism. These alterations in visible behavior may then indicate or even be diagnostic of alterations in the physical well-being of humans and other animals as they adapt to space environments or readapt to Earth--alterations that might not otherwise be detected without relatively invasive and frequently expensive procedures. Moreover, behavior and performance constitute the central standard for evaluating the mission success of spaceflight ventures. The success or failure of any excursion into space is primarily indexed by the ability of astronauts and cosmonauts to perform the tasks and experiments of any particular mission, to land a re-entry vehicle after extended exposure to microgravity (as with the space shuttle), or to make time-critical and life-saving repairs or other decisions while in orbit (as with the recent Mir events). Thus, understanding the effects spaceflight on behavior and performance is inherently important, in addition to those insights that behavior can provide about the physiological consequences of space adaptation.

22. WILEY CITY LINE BICENTENNIAL EXCURSION TROLLEY NEAR CONGDON ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. WILEY CITY LINE - BICENTENNIAL EXCURSION TROLLEY NEAR CONGDON CASTLE - Yakima Valley Transportation Company Interurban Railroad, Connecting towns of Yakima, Selah & Wiley City, Yakima, Yakima County, WA

On Geomagnetism and Paleomagnetism

NASA Technical Reports Server (NTRS)

Voorhies, Coerte V.

1998-01-01

A statistical description of Earth's broad scale, core-source magnetic field has been developed and tested. The description features an expected, or mean, spatial magnetic power spectrum that is neither "flat" nor "while" at any depth, but is akin to spectra advanced by Stevenson and McLeod. This multipole spectrum describes the magnetic energy range; it is not steep enough for Gubbins' magnetic dissipation range. Natural variations of core multipole powers about their mean values are to be expected over geologic time and are described via trial probability distribution functions that neither require nor prohibit magnetic isotropy. The description is thus applicable to core-source dipole and low degree non-dipole fields despite axial dipole anisotropy. The description is combined with main field models of modem satellite and surface geomagnetic measurements to make testable predictions of: (1) the radius of Earth's core, (2) mean paleomagnetic field intensity, and (3) the mean rates and durations of both dipole power excursions and durable axial dipole reversals. The predicted core radius is 0.7% above the 3480 km seismologic value. The predicted root mean square paleointensity (35.6 mu T) and mean Virtual Axial Dipole Moment (about 6.2 lx 1022 Am(exp 2)) are within the range of various mean paleointensity estimates. The predicted mean rate of dipole power excursions, as defined by an absolute dipole moment <20% of the 1980 value, is 9.04/Myr and 14% less than obtained by analysis of a 4 Myr paleointensity record. The predicted mean rate of durable axial dipole reversals (2.26/Myr) is 2.3% more than established by the polarity time-scale for the past 84 Myr. The predicted mean duration of axial dipole reversals (5533 yr) is indistinguishable from an observational value. The accuracy of these predictions demonstrates the power and utility of the description, which is thought to merit further development and testing. It is suggested that strong stable stratification of Earth's uppermost outer core leads to a geologically long interval of no dipole reversals and a very nearly axisymmetric field outside the core. Statistical descriptions of other planetary magnetic fields are outlined.

Intermittent Astrophysical Radiation Sources and Terrestrial Life

NASA Astrophysics Data System (ADS)

Melott, Adrian

2013-04-01

Terrestrial life is exposed to a variety of radiation sources. Astrophysical observations suggest that strong excursions in cosmic ray flux and spectral hardness are expected. Gamma-ray bursts and supernovae are expected to irradiate the atmosphere with keV to GeV photons at irregular intervals. Supernovae will produce large cosmic ray excursions, with time development varying with distance from the event. Large fluxes of keV to MeV protons from the Sun pose a strong threat to electromagnetic technology. The terrestrial record shows cosmogenic isotope excursions which are consistent with major solar proton events, and there are observations of G-stars suggesting that the rate of such events may be much higher than previously assumed. In addition there are unknown and unexplained astronomical transients which may indicate new classes of events. The Sun, supernovae, and gamma-ray bursts are all capable of producing lethal fluences, and some are expected on intervals of 10^8 years or so. The history of life on Earth is filled with mass extinctions at a variety of levels of intensity. Most are not understood. Astrophysical radiation may play a role, particularly from large increases in muon irradiation on the ground, and changes in atmospheric chemistry which deplete ozone, admitting increased solar UVB. UVB is strongly absorbed by DNA and proteins, and breaks the chemical bonds---it is a known carcinogen. High muon fluxes will also be damaging to such molecules, but experiments are needed to pin down the rate. Solar proton events which are not directly dangerous for the biota may nevertheless pose a major threat to modern electromagnetic technology through direct impact on satellites and magnetic induction of large currents in power grids, disabling transformers. We will look at the kind of events that are expected on timescales from human to geological, and their likely consequences.

The Anomalous Low State of LMC X-3

NASA Technical Reports Server (NTRS)

Smale, A. P.; Boyd, P. T.; Markwardt, C. B.

2009-01-01

Archival RXTE ASM and PCA observations of the black hole binary LMC X-3 reveal a dramatic and extended low state lasting from December 8, 2003 until March 18, 2004, unprecedented both in its Low luminosity (Lx(2-10keV)=4.2x 1035 ergs s-1, approximately 4 times fainter than ever before seen from LMC X-3 in its low/hard state, and representing 0.15% of its X-ray luminosity during the high/soft state); and Long duration (approximately equal to 100 days, as compared with 5-20 days for 'normal' low/hard state excursions). During this anomalous low state no significant variability is observed on timescales of days-weeks, and the spectrum is well described by a simple power law with index 1.7 plus or minus 0.2. We examine the variability characteristics of LMC X-3 before and after this event using conventional and topological methods, and show that with the exception of the anomalous low state itself the long-term behavior of the source in topological phase space can be completely described in terms of a well-understood nonlinear dynamics system known as the Duffing oscillator, implying that the accretion disk in LMC X-3 is a driven, dissipative system with two solutions competing for control of its time evolution. This work shows that dynamical information and constraints revealed by topological analysis methods can provide a valuable addition to traditional studies of accretion disk behavior.

Author Correction: Reliability and feasibility of gait initiation centre-of-pressure excursions using a Wii® Balance Board in older adults at risk of falling.

PubMed

Lee, James; Webb, Graham; Shortland, Adam P; Edwards, Rebecca; Wilce, Charlotte; Jones, Gareth D

2018-05-12

In the original publication, the article title was incorrectly published as 'Reliability and feasibility of gait initiation centre-of-pressure excursions using a Wii® Balance Board in older adults at risk of failing'. The correct title should read as 'Reliability and feasibility of gait initiation centre-of-pressure excursions using a Wii® Balance Board in older adults at risk of falling'.

Brownian excursions on combs

NASA Astrophysics Data System (ADS)

Dean, David S.; Jansons, Kalvis M.

1993-03-01

In this paper we use techniques from Ito excursion theory to analyze Brownian motion on generalized combs. Ito excursion theory is a little-known area of probability theory and we therefore present a brief introduction for the uninitiated. A general method for analyzing transport along the backbone of the comb is demonstrated and the specific case of a comb whose teeth are scaling branching trees is examined. We then present a recursive method for evaluating the distribution of the first passage times on hierarchical combs.

Sulfur cycling in plays an important role in the development of Ocean Anoxic Events

NASA Astrophysics Data System (ADS)

Gomes, M. L.; Raven, M. R.; Fike, D. A.; Gill, B. C.; Johnston, D. T.

2017-12-01

Ocean Anoxic Events (OAEs) are major carbon cycle perturbations marked by enhanced organic carbon deposition in the marine realm and carbon isotope excursions in organic and inorganic carbon. Although not as severe as the "big five" mass extinctions, OAEs had dire consequences for marine ecosystems and thus influenced Mesozoic evolutionary patterns. Sulfur cycle reconstructions provide insight into the biogeochemical processes that played a role in the development of OAEs because the sulfur cycle is linked with the carbon and oxygen cycles. We present sulfur and oxygen isotope records from carbonate-associated sulfate from the Toarcian OAE that documents a positive sulfate-oxygen isotope excursion of +6‰, which is similar to the magnitude of the positive sulfur isotope excursion documented at the same site and other globally distributed sites. This high-resolution record allows us to explore temporal variability in the onset of the isotopic excursions: the onset of the positive sulfate-oxygen isotope excursion occurs at the same stratigraphic interval as the onset of the positive carbon isotope excursion and both precede the onset of the positive sulfate-sulfur isotope excursion. Because oxygen is rapidly recycled during oxidative sulfur cycling, changes in oxidative sulfur cycling affect oxygen isotope values of sulfate without impacting sulfur isotope values. Thus, the early onset of the sulfate-oxygen isotope excursion implies a change in oxidative sulfur cycling, which is likely due to a shoaling of the zone of sulfate reduction. We explore the consequences of sulfate reduction zone shoaling for organic carbon preservation. Specifically, the sulfurization of organic matter, which makes organic matter less susceptible to degradation, occurs more rapidly when the top of the zone of sulfate reduction is near or above the sediment water interface. Therefore, we suggest that the shoaling of the sulfate reduction zone locally changed pathways of oxidative sulfur cycling and enhanced organic carbon preservation. Given synchronous changes in similar, globally-distributed depositional environments, this impacted the global biogeochemical cycles of oxygen, carbon, and nutrients in ways that sustained decreased oxygen availability and influenced extinction patterns of marine organisms.

RAVEN: a GUI and an Artificial Intelligence Engine in a Dynamic PRA Framework

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

C. Rabiti; D. Mandelli; A. Alfonsi

Increases in computational power and pressure for more accurate simulations and estimations of accident scenario consequences are driving the need for Dynamic Probabilistic Risk Assessment (PRA) [1] of very complex models. While more sophisticated algorithms and computational power address the back end of this challenge, the front end is still handled by engineers that need to extract meaningful information from the large amount of data and build these complex models. Compounding this problem is the difficulty in knowledge transfer and retention, and the increasing speed of software development. The above-described issues would have negatively impacted deployment of the new highmore » fidelity plant simulator RELAP-7 (Reactor Excursion and Leak Analysis Program) at Idaho National Laboratory. Therefore, RAVEN that was initially focused to be the plant controller for RELAP-7 will help mitigate future RELAP-7 software engineering risks. In order to accomplish this task, Reactor Analysis and Virtual Control Environment (RAVEN) has been designed to provide an easy to use Graphical User Interface (GUI) for building plant models and to leverage artificial intelligence algorithms in order to reduce computational time, improve results, and help the user to identify the behavioral pattern of the Nuclear Power Plants (NPPs). In this paper we will present the GUI implementation and its current capability status. We will also introduce the support vector machine algorithms and show our evaluation of their potentiality in increasing the accuracy and reducing the computational costs of PRA analysis. In this evaluation we will refer to preliminary studies performed under the Risk Informed Safety Margins Characterization (RISMC) project of the Light Water Reactors Sustainability (LWRS) campaign [3]. RISMC simulation needs and algorithm testing are currently used as a guidance to prioritize RAVEN developments relevant to PRA.« less

ELM suppression in helium plasmas with 3D magnetic fields

DOE PAGES

Evans, T. E.; Loarte, A.; Orlov, D. M.; ...

2017-06-21

Experiments in DIII-D, using non-axisymmetric magnetic perturbation fields in high-purity low toroidal rotation, 4He plasmas have resulted in Type-I edge localized mode (ELM) suppression and mitigation. Suppression is obtained in plasmas with zero net input torque near the L–H power threshold using either electron cyclotron resonant heating (ECRH) or balanced co- and counter-I p neutral beam injection (NBI) resulting in conditions equivalent to those expected in ITER's non-active operating phase. In low-power ECRH H-modes, periods with uncontrolled density and impurity radiation excursions are prevented by applying n = 3 non-axisymmetric magnetic perturbation fields. ELM suppression results from a reduction andmore » an outward shift of the electron pressure gradient peak compared to that in the high-power ELMing phase. Here, the change in the electron pressure gradient peak is primarily due to a drop in the pedestal temperature rather than the pedestal density.« less

ELM suppression in helium plasmas with 3D magnetic fields

NASA Astrophysics Data System (ADS)

Evans, T. E.; Loarte, A.; Orlov, D. M.; Grierson, B. A.; Knölker, M. M.; Lyons, B. C.; Cui, L.; Gohil, P.; Groebner, R. J.; Moyer, R. A.; Nazikian, R.; Osborne, T. H.; Unterberg, E. A.

2017-08-01

Experiments in DIII-D, using non-axisymmetric magnetic perturbation fields in high-purity low toroidal rotation, 4He plasmas have resulted in Type-I edge localized mode (ELM) suppression and mitigation. Suppression is obtained in plasmas with zero net input torque near the L-H power threshold using either electron cyclotron resonant heating (ECRH) or balanced co- and counter-I p neutral beam injection (NBI) resulting in conditions equivalent to those expected in ITER’s non-active operating phase. In low-power ECRH H-modes, periods with uncontrolled density and impurity radiation excursions are prevented by applying n  =  3 non-axisymmetric magnetic perturbation fields. ELM suppression results from a reduction and an outward shift of the electron pressure gradient peak compared to that in the high-power ELMing phase. The change in the electron pressure gradient peak is primarily due to a drop in the pedestal temperature rather than the pedestal density.

An Excursion in Applied Mathematics.

ERIC Educational Resources Information Center

von Kaenel, Pierre A.

1981-01-01

An excursion in applied mathematics is detailed in a lesson deemed well-suited for the high school student or undergraduate. The problem focuses on an experimental missile guidance system simulated in the laboratory. (MP)

Validation of color Doppler sonography for evaluating relative displacement between the flexor tendon and subsynovial connective tissue.

PubMed

Tat, Jimmy; Kociolek, Aaron M; Keir, Peter J

2015-04-01

A common pathologic finding in carpal tunnel syndrome is fibrosis and thickening of the subsynovial connective tissue. This finding suggests an etiology of excessive shear forces, with relative longitudinal displacement between the flexor tendon and adjacent subsynovial connective tissue. The purpose of this study was to validate color Doppler sonography for measurement of tendon displacement over time. Eight unmatched fresh frozen cadaver arms were used to evaluate color Doppler sonography for measurement of tendon displacement. The middle flexor digitorum superficialis tendon was moved through a physiologic excursion of 20 mm at 3 different tendon velocities (50, 100, and 150 mm/s). We found that color Doppler sonography provided accurate measurement of tendon displacement, with absolute errors of -0.05 mm (50 mm/s), -1.24 mm (100 mm/s), and -2.36 mm (150 mm/s) on average throughout the tendon excursion range. Evaluating relative displacement between the tendon and subsynovial connective tissue during finger flexion-extension movements also offered insight into the gliding mechanism of the subsynovial connective tissue. During flexion, we observed a curvilinear increase in relative displacement, with greater differential motion at the end range of displacement, likely due to the sequential stretch of the fibrils between successive layers of the subsynovial connective tissue. In extension, there was a linear return in relative displacement, suggesting a different unloading mechanism characterized by uniform relaxation of fibrils. We demonstrated the validity of color Doppler displacement for use in the evaluation of relative motion. Color Doppler sonography is useful in our understanding of the behavior of the subsynovial connective tissue during tendon excursion, which may elucidate the role of finger motion in the etiology of shear injury. © 2015 by the American Institute of Ultrasound in Medicine.

Vessel Cold-Ironing Using a Barge Mounted PEM Fuel Cell: Project Scoping and Feasibility.

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

Pratt, Joseph William; Harris, Aaron P.

2013-01-01

A barge-mounted hydrogen-fueled proton exchange membrane (PEM) fuel cell system has the potential to reduce emissions and fossil fuel use of maritime vessels in and around ports. This study determines the technical feasibility of this concept and examines specific options on the U.S. West Coast for deployment practicality and potential for commercialization.The conceptual design of the system is found to be straightforward and technically feasible in several configurations corresponding to various power levels and run times.The most technically viable and commercially attractive deployment options were found to be powering container ships at berth at the Port of Tacoma and/or Seattle,more » powering tugs at anchorage near the Port of Oakland, and powering refrigerated containers on-board Hawaiian inter-island transport barges. Other attractive demonstration options were found at the Port of Seattle, the Suisun Bay Reserve Fleet, the California Maritime Academy, and an excursion vessel on the Ohio River.« less

Instant axis of rotation of L4-5 motion segment--a biomechanical study on cadaver lumbar spine.

PubMed

Sengupta, Dilip K; Demetropoulos, Constantine K; Herkowitz, Harry N

2011-06-01

The instant axis of rotation (IAR) is an important kinematic property to characterise of lumbar spine motion. The goal of this biomechanical study on cadaver lumbar spine was to determine the excursion of the IAR for flexion (FE), lateral bending (LB) and axial rotation (AR) motion at L4-5 segment. Ten cadaver lumbar spine specimens were tested in a 6 degrees-of-freedom spine tester with continuous clyclical loading using pure moment and follower pre-load, to produce physiological motion. The specimens were x-rayed and CT scanned prior to testing to identify marker position. Continuous motion tracking was done by Optotrak motion capture device. A continuous tracking of the IAR excursion was calculated from the continuous motions capturedata using a computer programme. IAR translates forward in flexion and backwards in extension with mean excursion of 26.5 mm (+/- 5.6 SD). During LB motion, IAR translates laterally in the same direction, and the mean excursion was 15.35 mm (+/- 8.75 SD). During axial rotation the IAR translates in the horizontal plane in a semicircular arc, around the centre of the vertebral body, but the IAR translates in the opposite direction of rotation. The IAR excursion was faster and larger during neutral zone motion in FE and LB, but uniform for AR motion. This is the first published data on the continuous excursion of IAR of a lumbar motion segment. The methodology is accurate and precise, but not practicable for in vivo testing.

Analysis of Coastal Sediment Transport Processes from Wrightsville Beach to Fort Fisher, North Carolina.

DTIC Science & Technology

1981-06-01

the erosional phase of beach behavior is the continual exposure of "fresh" beach sediment which may not have the approprixte sediment distribution...The time scale was reset to zero at the time of fill (t0O), and so the initial loss of beach fill after time t was St. Values of S (Fig. 19) for...varying time increments up to tt 1 were plotted on semilog paper. Figure 20 shows the results of these plots for the MLW, MSL, and NHW excursion curves

The Carnian (Late Triassic) carbon isotope excursion: new insights from the terrestrial realm

NASA Astrophysics Data System (ADS)

Miller, Charlotte; Kürschner, Wolfram; Peterse, Francien; Baranyi, Viktoria; Reichart, Gert-Jan

2016-04-01

The geological record contains evidence for numerous pronounced perturbations in the global carbon cycle, some of which are associated with eruptions from large igneous provinces (LIP), and consequently, ocean acidification and mass extinction. In the Carnian (Late Triassic), evidence from sedimentology and fossil pollen points to a significant change in climate, resulting in biotic turnover: during a period termed the 'Carnian Pluvial Event' (CPE). Additionally, during the Carnian, large volumes of flood basalts were erupted from the Wrangellia LIP (western North America). Evidence from the marine realm suggests a fundamental relationship between the CPE, a global 'wet' period, and the injection of light carbon into the atmosphere from the LIP. Here we provide the first evidence from the terrestrial realm of a significant negative δ13C excursion through the CPE recorded in the sedimentary archive of the Wiscombe Park Borehole, Devon (UK). Both total organic matter and plant leaf waxes reflect a gradual carbon isotope excursion of ~-5‰ during this time interval. Our data provides evidence for the global nature of this isotope excursion, supporting the hypothesis that the excursion was likely the result of an injection of light carbon into the atmosphere from the Wrangellia LIP.

Geometrical effects of conventional and digital prosthodontic planning wax-ups on lateral occlusal contact number, contact area, and steepness.

PubMed

Abduo, Jaafar

2017-01-01

This study evaluated and compared the effect of conventional and digital wax-ups on three lateral occlusion variables: contact number, contact area, and steepness. Dental casts of 10 patients with Angle Class I relationship were included in the study. All patients required fixed prosthodontic treatment that would affect lateral occlusion. The casts of all patients received conventional and digital wax-ups. For pretreatment, conventional wax-up, and digital wax-up casts, contact number, contact area, and occlusion steepness were measured at four lateral positions, that is, at excursions of 0.5, 1.0, 2.0, and 3.0 mm from maximal intercuspation. Lateral occlusion scheme variables were affected by use of diagnostic wax-ups. For all types of casts, contact number decreased as excursion increased. The two types of wax-ups had similar contact number patterns, and contact number was significantly greater for these casts than for pretreatment casts in the earlier stages of excursion. Similarly, contact area gradually decreased with increasing excursion in the pretreatment and conventional and digital wax-up casts. There was only a minimal decrease in occlusion steepness as excursion increased. However, lateral occlusion was generally steeper for digital wax-up casts.

Self-adaptive predictor-corrector algorithm for static nonlinear structural analysis

NASA Technical Reports Server (NTRS)

Padovan, J.

1981-01-01

A multiphase selfadaptive predictor corrector type algorithm was developed. This algorithm enables the solution of highly nonlinear structural responses including kinematic, kinetic and material effects as well as pro/post buckling behavior. The strategy involves three main phases: (1) the use of a warpable hyperelliptic constraint surface which serves to upperbound dependent iterate excursions during successive incremental Newton Ramphson (INR) type iterations; (20 uses an energy constraint to scale the generation of successive iterates so as to maintain the appropriate form of local convergence behavior; (3) the use of quality of convergence checks which enable various self adaptive modifications of the algorithmic structure when necessary. The restructuring is achieved by tightening various conditioning parameters as well as switch to different algorithmic levels to improve the convergence process. The capabilities of the procedure to handle various types of static nonlinear structural behavior are illustrated.

Paleointensity and 40Ar/39Ar geochronology of basalts at Gamarri, Ethiopia: Correlation with the Réunion subchron and Huckleberry Ridge excursion?

NASA Astrophysics Data System (ADS)

Kindley, C.; Macho, A.; Tsegaye, M. A.; Feinberg, J. M.; Singer, B. S.; Jicha, B. R.; Brown, M. C.; Birke, T. K.

2012-12-01

Characterization of the geomagnetic field during subchrons, reversals, and excursions is vital to understanding geodynamo processes and interactions across the core-mantle boundary. Moreover, an accurate timescale for geomagnetic field instabilities is critical to global high resolution stratigraphy. The Réunion subchron and Huckleberry Ridge excursion are ideal candidates for study due to globally distributed recordings in both sedimentary and igneous rocks. We present new full-vector paleomagnetic data for 30 basaltic flows from the Gamarri volcanic section in the Afar region of Ethiopia and 11 40Ar/39Ar ages. Paleointensities were calculated using the LTD-DHT Shaw technique and results generally agree with those of Carlut et al. (1999). Two geomagnetic instabilities are recorded, an older excursion and a younger period of normal polarity within the reversed Matuyama chron. Our results show a longer duration of low (<20 μT) paleointensity in the oldest flows and more variable low paleointensity values in the younger flows, and are generally lower than Thellier-style values of Carlut et al. (1999). Relative to 28.201 Ma Fish Canyon sanidine, plateau 40Ar/39Ar ages of the youngest (GB21) and oldest (GA02) flows are 2.029 ± 0.041 (2σ) and 2.410 ± 0.130 Ma, respectively. This eruptive duration is longer than that reported by Kidane et al. (1999), where the unspiked K-Ar method yields ages for GB23 (2 flows overlying GB21) and GA02 of 2.02 ± 0.08 (2σ) and 2.14 ± 0.12 Ma, respectively. 40Ar/39Ar ages of 4 lavas within the normal polarity zone in the upper section are between 2.063 ± 0.044 and 2.118 ± 0.057 Ma, but are indistinguishable at 2σ. These flows may sample the Huckleberry Ridge excursion (2.086 ± 0.016 Ma, Singer et al. 2004), the Réunion subchron (2.153-2.115 Ma, Channell et al. 2003), or both. Given several 40Ar/39Ar ages >2.2 Ma, the older excursion in the Gamarri section is not consistent with the Réunion subchron, and can be linked to any of several excursions occurring between ~2.2 and ~2.5 Ma. These excursions have been observed within records from ODP 982 (Channell & Guyodo, 2004) and IODP U1314 (Ohno et al., 2012), as well as within the GPTS as cryptochron C2r.2r-1 (originally dated as 2.420 to 2.441 Ma by Cande & Kent, 1995). Thus, we no longer interpret the excursion recorded in the lower portion of the Gamarri section to be part of the Réunion subchron and recommend that it be omitted from efforts to construct integrated global field models across the Huckleberry Ridge excursion and Réunion subchron.

Paleomagnetic record for the past 80 ka from the Mahanadi basin, Bay of Bengal

NASA Astrophysics Data System (ADS)

Usapkar, A.; Dewangan, P.; Mazumdar, A.; Krishna, K. S.; Ramprasad, T.; Badesab, F. K.; Patil, M.; Gaikwad, V. V.

2018-01-01

High resolution paleomagnetic investigations were performed on a 50.08 m long sediment core (MD161/20) from Mahanadi basin, Bay of Bengal. Core yielded reliable paleomagnetic results for top 20 m below seafloor (mbsf) which spans about 80 ka. Based on the analysis of rock magnetic data, the core is subdivided into five distinct Zones: Zone 1 and Zone 2 cover top 20 mbsf and do not show any abrupt change in magnetic mineralogy, concentration and grain size. Zones 3 and 5 show significant reduction in χLF, χARM and SIRM due to dissolution of magnetic minerals. Zone 4 shows moderate values of χLF and SIRM. The low value of χARM suggests that magnetic signal is mostly carried by magnetic grains in PSD/MD state. The paleomagnetic data for the top 20 mbsf show four prominent geomagnetic excursions at ∼9 mbsf, ∼13.5 to 15 mbsf, ∼16.3 mbsf and ∼18 to 18.2 mbsf. The age-depth relationship is established using stratigraphic correlation between well-dated sedimentary core NGHP-01-19B and the core MD161/20. The ages of the observed excursions correspond to ∼18 to 20 ka, ∼42 to 49 ka, ∼54 to 57 ka and ∼69 to 70 ka. The excursions at ∼42 to 49 ka, ∼54 to 57 ka, and ∼67 to 70 ka is similar to the known excursions the Laschamp and the split Norwegian-Greenland Sea events (NGS-I and NGS-II). The excursion at 18-20 ka is not observed globally and may be related to lithological/sedimentological changes occurring during last glacial maxima (LGM). The virtual geomagnetic path (VGP) of Laschamp excursion traces clockwise loop. All excursions identified in present study fall in the periods of relatively low paleointensity.

Improved Quaternary North Atlantic stratigraphy using relative paleointensity (RPI), oxygen isotopes, and magnetic excursions (Invited)

NASA Astrophysics Data System (ADS)

Channell, J. E.

2013-12-01

Improving the resolution of Quaternary marine stratigraphy is one of the major challenges in paleoceanography. IODP Expedition 303/306, and ODP Legs 162 and 172, have yielded multiple high-resolution records (mean sedimentation rates in the 7-20 cm/kyr range) of relative paleointensity (RPI) that are accompanied by oxygen isotope data and extend through much of the Quaternary. Tandem fit of RPI and oxygen isotope data to calibrated templates (LR04 and PISO), using the Match protocol, yields largely consistent stratigraphies, implying that both RPI and oxygen isotope data are dominated by regional/global signals. Based on the recent geomagnetic field, RPI can be expected to be a global signal (i.e. dominated by the axial dipole field) when recorded at sedimentation rates less than several decimeters/kyr. Magnetic susceptibility, on the other hand, is a local/regional lithologic signal, and therefore less useful for long-distance correlation. Magnetic excursions are directional phenomena and, when adequately recorded, are manifest as paired reversals in which the virtual geomagnetic poles (VGPs) reach high latitudes in the opposite hemisphere, and they occupy minima in RPI records. Reversed VGPs imply that excursions are attributable to the main axial dipole, and therefore provide global stratigraphy. The so-called Iceland Basin excursion is recorded at many IODP/ODP sites and lies at the MIS 6/7 boundary at ~188 ka, with a duration of 2-3 kyr. Other excursions in the Brunhes chron are less commonly recorded because their duration (perhaps <~1 kyr) requires sedimentation rates >20 cm/kyr to be adequately recorded. On the other hand, several excursions within the Matuyama Chron are more commonly recorded in North Atlantic drift sediments due to relatively elevated durations. With some notable exceptions (e.g. Iberian Margin), high quality RPI records from North Atlantic sediments, together with magnetic excursions, can be used in tandem with oxygen isotope data to strengthen Quaternary (North Atlantic) stratigraphy.

Volcanic records of the Laschamp geomagnetic excursion from Mt Ruapehu, New Zealand

NASA Astrophysics Data System (ADS)

Ingham, E.; Turner, G. M.; Conway, C. E.; Heslop, D.; Roberts, A. P.; Leonard, G.; Townsend, D.; Calvert, A.

2017-08-01

We present palaeodirectional records of the Laschamp geomagnetic excursion from lavas on Mt Ruapehu, New Zealand. Fourteen lava flows on the northwestern and southern flanks of Mt Ruapehu, with 40Ar/39Ar weighted mean plateau ages that range from 46.3 ± 2.0 to 39.9 ± 1.4 ka, were studied. The youngest and older flows carry a normal polarity magnetization; however, six flows, dated between 46.3 ± 2.0 and 42.7 ± 1.8 ka, record excursional directions. Three of these flows record southerly palaeomagnetic declinations and negative inclinations that agree well with a published Laschamp record from the Auckland Volcanic Field (AVF). Together, the AVF and Mt Ruapehu lavas currently represent the only volcanic records of the Laschamp excursion outside the Chaîne des Puys region, France. Thus, they make an important contribution to the global set of Laschamp excursion records. Virtual geomagnetic pole (VGP) groups for the New Zealand and French records early in the excursion are compatible with a dipole-dominated field that rotated to an equatorial orientation while simultaneously decaying in strength. In contrast, younger excursional flows from France and New Zealand yield separate VGP groups, which suggest either that the field had a nondipolar morphology in this later phase, or that the VGP groups were not synchronous. 40Ar/39Ar ages for the Mt Ruapehu record are on average slightly older than published northern hemisphere ages and from the relative palaeointensity minimum in the GLOPIS sedimentary stack. Although few individual ages differ significantly at the 2σ level, the spread suggests an overall excursion duration that is longer than the currently accepted 1500 years. This age spread may result from excess Ar in magmas at the time of the eruption biasing the results to slightly older ages, or from non-synchronous excursional field behaviour at near-antipodal locations, or, possibly, a precursory phase prior to the main excursion.

Testing the Self-Consistency of the Excursion Set Approach to Predicting the Dark Matter Halo Mass Function

NASA Astrophysics Data System (ADS)

Achitouv, I.; Rasera, Y.; Sheth, R. K.; Corasaniti, P. S.

2013-12-01

The excursion set approach provides a framework for predicting how the abundance of dark matter halos depends on the initial conditions. A key ingredient of this formalism is the specification of a critical overdensity threshold (barrier) which protohalos must exceed if they are to form virialized halos at a later time. However, to make its predictions, the excursion set approach explicitly averages over all positions in the initial field, rather than the special ones around which halos form, so it is not clear that the barrier has physical motivation or meaning. In this Letter we show that once the statistical assumptions which underlie the excursion set approach are considered a drifting diffusing barrier model does provide a good self-consistent description both of halo abundance as well as of the initial overdensities of the protohalo patches.

Jaw motion during gum-chewing in children with primary dentition.

PubMed

Kubota, Naoko; Hayasaki, Haruaki; Saitoh, Issei; Iwase, Yoko; Maruyama, Tomoaki; Inada, Emi; Hasegawa, Hiroko; Yamada, Chiaki; Takemoto, Yoshihiko; Matsumoto, Yuko; Yamasaki, Youichi

2010-01-01

This study was undertaken to characterize jaw motion during mastication in children with primary dentition and to compare jaw motion with that in adults. The means and the variances of the traditional parameters for the chewing cycle, i.e., duration, excursive ranges and 3-D distances of travel at the lower incisor, molars and condyles were analyzed and compared in 23 children and 25 female adults. The duration of opening in children was significantly shorter than that of adults. Significant differences between children and adults were observed in lateral and vertical excursion of the incisor, lateral excursion at the molars, and vertical excursion at the condyles. Many of these measurements had larger between-subject and between-cycle variances in children than adults, suggesting that chewing motion in children has not yet matured. The results of this study indicate that chewing motion in children is different from that of adults.

Aptian Carbon Isotope Stratigraphy in Sierra del Rosario, Northeastern Mexico

NASA Astrophysics Data System (ADS)

Barragan-Manzo, R.; Moreno-Bedmar, J.; Nuñez, F.; Company, M.

2013-05-01

In most recent years Aptian carbon isotope stratigraphy has been widely studied in Europe where isotopic stages have been developed to correlate global events. Two negative excursions have been recorded in the Lower Aptian, the older is OAE 1a in the middle part, and a younger negative excursion labeled "Aparein level", which occurs in the uppermost part of the Lower Aptian. In Mexico previous works reported a carbon isotope negative excursion in the lowermost part of the La Peña Formation that was assigned to the onset of Oceanic Anoxic Event 1a (=OAE 1a). In this work we study the isotopic record of the δ13Ccarb of 32 bulk rock samples of limestone from the uppermost part of the Cupido Formation and the lower part of the La Peña Formation at the Francisco Zarco Dam Section (=FZD), Durango State, northeastern Mexico. The isotopic data are calibrated using the latest ammonite biostratigraphic biozonation of the Aptian. This age calibration allows us to make a precise correlation between the carbon isotopic record of Mexico and several European sections (e.g. Spain and France). In the studied Francisco Zarco Dam section we recognize a negative carbon isotopic excursion in the Dufrenoyia justinae ammonite Zone that corresponds to the "Aparein level", which we correlate using the ammonite zonation of others European sections (Figure 1). This correlation allows us to see how the negative excursion that characterizes the "Aparein level" is consistent with the C7 segment. Thus, our recent stratigraphic study allows us to conclude that the ammonite record in the lowermost part of the La Peña Formation is regionally isochronous, and correlates with the Dufrenoyia justinae Zone and Lower Aptian isotope interval C7. In agreement to these biostratigraphic data, the supposed record of the OAE 1a in the lowermost part of the La Peña Formation is not correct, and the carbon isotope negative excursion must be assigned to the younger event "Aparein level". Taking this into account, other Lower Aptian negative excursions reported in the literature and assigned to the OAE 1a, perhaps, must be reconsidered to distinguish among the two Lower Aptian negative excursions.; Figure 1: Isotopic curve of the FZD section compared with one section of Spain. The sharp negative peak in the Mexican section is compared with the Spanish section (see the arrow).

A Comparison of Paleomagnetic Secular Variation during MIS 7-10 between the Bering Sea (IODP Ex. 323) and North Atlantic Ocean (ODP Leg 172): Implications for the space/time pattern of field and environmental variability (Invited)

NASA Astrophysics Data System (ADS)

Lund, S.; Okada, M.; Acton, G.; Clement, B. M.; Stoner, J. S.; Platzman, E. S.

2013-12-01

Detailed records of Brunhes paleomagnetic secular variation (PSV) during Marine Isotope Stages (MIS) 7-10 have been recovered from four IODP Ex. 323 sites in the Bering Sea (U1339, U1343-U1345) and four ODP Leg 172 sites from the subtropical North Atlantic Ocean (1060-1063). Reproducible records of PSV (both directions and paleointensity) have been recovered from three or more holes at each site and correlated among the four independent sites in each region. These PSV records provide an unprecedented database for considering patterns of long-term secular variation and evidence for excursional field behavior on a larger than individual regional scale. We will present reproducible evidence for sustained long-term secular variation in each region and assess the extent to which they may be interrelated. We have identified the times of magnetic field excursions 7α, 7β, 8α, 9α, and 9β in the Atlantic records and correlated those times to the Bering Sea records. There are no true excursions in the Bering Sea at those times, but several of these intervals mark the most anomalous field behavior in the Bering Sea during MIS 7-10. In both regions, the PSV also serves as a high-resolution chronostratigraphic tool for regional correlation of environmental variability. Both regions show clear, reproducible evidence among the sites for synchronous millennial-scale environmental variability that has not been diagnosed previously.

Mass breakdown model of solar-photon sail shuttle: The case for Mars

NASA Astrophysics Data System (ADS)

Vulpetti, Giovanni; Circi, Christian

2016-02-01

The main aim of this paper is to set up a many-parameter model of mass breakdown to be applied to a reusable Earth-Mars-Earth solar-photon sail shuttle, and analyze the system behavior in two sub-problems: (1) the zero-payload shuttle, and (2) given the sailcraft sail loading and the gross payload mass, find the sail area of the shuttle. The solution to the subproblem-1 is of technological and programmatic importance. The general analysis of subproblem-2 is presented as a function of the sail side length, system mass, sail loading and thickness. In addition to the behaviors of the main system masses, useful information for future work on the sailcraft trajectory optimization is obtained via (a) a detailed mass model for the descent/ascent Martian Excursion Module, and (b) the fifty-fifty solution to the sailcraft sail loading breakdown equation. Of considerable importance is the evaluation of the minimum altitude for the rendezvous between the ascent rocket vehicle and the solar-photon sail propulsion module, a task performed via the Mars Climate Database 2014-2015. The analysis shows that such altitude is 300 km; below it, the atmospheric drag prevails over the solar-radiation thrust. By this value, an example of excursion module of 1500 kg in total mass is built, and the sailcraft sail loading and the return payload are calculated. Finally, the concept of launch opportunity-wide for a shuttle driven by solar-photon sail is introduced. The previous fifty-fifty solution may be a good initial guess for the trajectory optimization of this type of shuttle.

Linking nanoscale mechanical behavior to bulk physical properties and phenomena of energetic materials

NASA Astrophysics Data System (ADS)

Taw, Matthew R.

The hardness and reduced modulus of aspirin, RDX, HMX, TATB, FOX-7, ADAAF, and TNT/CL-20 were experimentally measured with nanoindentation. These values are reported for the first time using as-received micron sized crystals of energetic materials with no additional mechanical processing. The results for TATB, ADAAF, and TNT/CL-20 are the first of their kind, while comparisons to previous nanoindentation studies on large, carefully grown single crystals of the other energetic materials show that mechanical properties of the larger crystals are comparable to crystals in the condition they are practically used. Measurements on aspirin demonstrate the variation that can occur between nanoindentation indents based on the orientation of a Berkovich tip relative to the surface of the sample. The Hertzian elastic contact model was used to analyze the materials initial yield, or pop-in, behavior. The length, energy, indentation load, and shear stress at initial yielding were used to characterize each material. For the energetic materials the length and energy of the yield excursions were compared to the drop weight sensitivity. This comparison revealed a general trend that more impact sensitive materials have longer, more severe pop-in excursions. Hot spot initiation mechanisms involving crystal defects such as void collapses and dislocation pile-up followed by avalanche are supported by these trends. While this only takes one aspect of impact sensitivity into consideration, if this trend is observed in a larger range of energetics these methods could possibly be used to great advantage in the early stages of new explosives synthesis to obtain an estimation of drop weight sensitivity.

Paleomagnetic record determined in cores from deep research wells in the Quaternary Santa Clara basin, California

USGS Publications Warehouse

Mankinen, Edward A.; Wentworth, Carl M.

2016-01-01

The Mono Lake (ca. 32 ka), Pringle Falls (ca. 210 ka), and Big Lost (ca. 565 ka) geomagnetic excursions all seem to be represented in the Santa Clara Valley wells. Possible correlations to the Laschamp (ca. 40 ka) and Blake (ca. 110 ka) excursions are also noted. Three additional excursions that have apparently not been previously reported from western North America occur within cycle 6 (between 536 and 433 ka), near the base of cycle 5 (after 433 ka), and near the middle of cycle 2 (before ca. 75 ka).

Scaling fixed-field alternating gradient accelerators with a small orbit excursion.

PubMed

Machida, Shinji

2009-10-16

A novel scaling type of fixed-field alternating gradient (FFAG) accelerator is proposed that solves the major problems of conventional scaling and nonscaling types. This scaling FFAG accelerator can achieve a much smaller orbit excursion by taking a larger field index k. A triplet focusing structure makes it possible to set the operating point in the second stability region of Hill's equation with a reasonable sensitivity to various errors. The orbit excursion is about 5 times smaller than in a conventional scaling FFAG accelerator and the beam size growth due to typical errors is at most 10%.

Four-dimensional analysis by high-speed holographic imaging reveals a chiral memory of sperm flagella.

PubMed

Muschol, Michael; Wenders, Caroline; Wennemuth, Gunther

2018-01-01

Here high-speed Digital Holographic Microscopy (DHM) records sperm flagellar waveforms and swimming paths in 4 dimensions (X, Z, and t). We find flagellar excursions into the Z-plane nearly as large as the envelope of the flagellar waveform projected onto the XY-plane. These Z-plane excursions travel as waves down the flagellum each beat cycle. DHM also tracks the heads of free-swimming sperm and the dynamics and chirality of rolling of sperm around their long axis. We find that mouse sperm roll CW at the maximum positive Z-plane excursion of the head, then roll CCW at the subsequent maximum negative Z-plane excursion. This alternating chirality of rolling indicates sperm have a chiral memory. Procrustes alignments of path trajectories for sequences of roll-counterroll cycles show that path chirality is always CW for the cells analyzed in this study. Human and bull sperm lack distinguishable left and right surfaces, but DHM still indicates coordination of Z-plane excursions and rolling events. We propose that sperm have a chiral memory that resides in a hypothetical elastic linkage within the flagellar machinery, which stores some of the torque required for a CW or CCW roll to reuse in the following counter-roll. Separate mechanisms control path chirality.

Design of an unmanned Martian polar exploration system

NASA Technical Reports Server (NTRS)

Baldwin, Curt; Chitwood, Denny; Demann, Brian; Ducheny, Jordan; Hampton, Richard; Kuhns, Jesse; Mercer, Amy; Newman, Shawn; Patrick, Chris; Polakowski, Tony

1994-01-01

The design of an unmanned Martian polar exploration system is presented. The system elements include subsystems for transportation of material from earth to Mars, study of the Martian north pole, power generation, and communications. Early next century, three Atlas 2AS launch vehicles will be used to insert three Earth-Mars transfer vehicles, or buses, into a low-energy transfer orbit. Capture at Mars will be accomplished by aerobraking into a circular orbit. Each bus contains four landers and a communications satellite. Six of the twelve total landers will be deployed at 60 deg intervals along 80 deg N, and the remaining six landers at 5 deg intervals along 30 deg E from 65 deg N to 90 deg N by a combination of retrorockets and parachutes. The three communications satellites will be deployed at altitudes of 500 km in circular polar orbits that are 120 deg out of phase. These placements maximize the polar coverage of the science and communications subsystems. Each lander contains scientific equipment, two microrovers, power supplies, communications equipment, and a science computer. The lander scientific equipment includes a microweather station, seismometer, thermal probe, x-ray spectrometer, camera, and sounding rockets. One rover, designed for short-range (less than 2 km) excursions from the lander, includes a mass spectrometer for mineral analysis, an auger/borescope system for depth profiling, a deployable thermal probe, and charge coupled device cameras for terrain visualization/navigation. The second rover, designed for longer-range (2-5 km) excursions from the lander, includes radar sounding/mapping equipment, a seismometer, and laser ranging devices. Power for all subsystems is supplied by a combination of solar cells, Ni-H batteries, and radioisotope thermoelectric generators. Communications are sequenced from rovers, sounding rockets, and remote sensors to the lander, then to the satellites, through the Deep Space Network to and from earth.

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

Gevorgian, Vahan; Zhang, Yingchen

The electrical frequency of an interconnected power system must be maintained close its nominal level at all times. Excessive under- and overfrequency excursions can lead to load shedding, instability, machine damage, and even blackouts. There is a rising concern in the electric power industry in recent years about the declining amount of inertia and primary frequency response (PFR) in many interconnections. This decline may continue due to increasing penetrations of inverter-coupled generation and the planned retirements of conventional thermal plants. Inverter-coupled variable wind generation is capable of contributing to PFR and inertia with a response that is different from thatmore » of conventional generation. It is not yet entirely understood how such a response will affect the system at different wind power penetration levels. The modeling work presented in this paper evaluates the impact of wind generation's provision of these active power control strategies on a large, synchronous interconnection. All simulations were conducted on the U.S. Western Interconnection with different levels of instantaneous wind power penetrations (up to 80%). The ability of wind power plants to provide PFR - and a combination of synthetic inertial response and PFR - significantly improved the frequency response performance of the system.« less

Biology Excursions

ERIC Educational Resources Information Center

Baldock, R. N.

1973-01-01

Provides many useful suggestions and cautions for planning and executing a biology field excursion. Specific procedures are outlined for investigating land communities and coastal areas, and a number of follow-up laboratory activities are described. The appendix provides an extensive bibliography with useful comments on the literature. (JR)

Improving the Science Excursion: An Educational Technologist's View

ERIC Educational Resources Information Center

Balson, M.

1973-01-01

Analyzes the nature of the learning process and attempts to show how the three components of a reinforcement contingency, the stimulus, the response and the reinforcement can be utilized to increase the efficiency of a typical science learning experience, the excursion. (JR)

Influence of dietary protein on postprandial blood glucose levels in individuals with Type 1 diabetes mellitus using intensive insulin therapy.

PubMed

Paterson, M A; Smart, C E M; Lopez, P E; McElduff, P; Attia, J; Morbey, C; King, B R

2016-05-01

To determine the effects of protein alone (independent of fat and carbohydrate) on postprandial glycaemia in individuals with Type 1 diabetes mellitus using intensive insulin therapy. Participants with Type 1 diabetes mellitus aged 7-40 years consumed six 150 ml whey isolate protein drinks [0 g (control), 12.5, 25, 50, 75 and 100] and two 150 ml glucose drinks (10 and 20 g) without insulin, in randomized order over 8 days, 4 h after the evening meal. Continuous glucose monitoring was used to assess postprandial glycaemia. Data were collected from 27 participants. Protein loads of 12.5 and 50 g did not result in significant postprandial glycaemic excursions compared with control (water) throughout the 300 min study period (P > 0.05). Protein loads of 75 and 100 g resulted in lower glycaemic excursions than control in the 60-120 min postprandial interval, but higher excursions in the 180-300 min interval. In comparison with 20 g glucose, the large protein loads resulted in significantly delayed and sustained glucose excursions, commencing at 180 min and continuing to 5 h. Seventy-five grams or more of protein alone significantly increases postprandial glycaemia from 3 to 5 h in people with Type 1 diabetes mellitus using intensive insulin therapy. The glycaemic profiles resulting from high protein loads differ significantly from the excursion from glucose in terms of time to peak glucose and duration of the glycaemic excursion. This research supports recommendations for insulin dosing for large amounts of protein. © 2015 The Authors. Diabetic Medicine published by John Wiley & Sons Ltd on behalf of Diabetes UK.

Sex-specific gait adaptations prior to and up to six months after ACL reconstruction

PubMed Central

Stasi, Stephanie L. Di; Hartigan, Erin H.; Snyder-Mackler, Lynn

2015-01-01

STUDY DESIGN Controlled longitudinal laboratory study. OBJECTIVES Compare sagittal plane gait mechanics of men and women before and up to 6 months after anterior cruciate ligament reconstruction (ACLR). BACKGROUND Aberrant gait patterns are ubiquitous after anterior cruciate ligament (ACL) rupture and persist after ACLR despite skilled physical therapy. Sex influences post-operative function and second ACL injury risk, but its influence on gait adaptations after injury have not been investigated. METHODS Sagittal plane knee and hip joint excursions during midstance and internal knee and hip extension moments at peak knee flexion were collected on 12 women and 27 men using 3-dimensional gait analysis before (Screen) and after pre-operative physical therapy (Pre-sx), and 6 months after ACLR (6mo). Repeated measures analysis of variance models were used to determine whether limb asymmetries changed differently over time in men and women. RESULTS Significant time x limb x sex interactions were identified for hip and knee excursions and internal knee extension moments (P≤.007). Both sexes demonstrated smaller knee excursions on the involved compared to the uninvolved knee at each time point (P≤.007), but only women demonstrated a decrease in the involved knee excursion from pre-sx to 6mo (P=.03). Women also demonstrated smaller hip excursions (P<.001) and internal knee extension moments (P=.005) on the involved limb compared to the uninvolved limb at 6mo. Men demonstrated smaller hip excursions and knee moments on the involved limb compared to the uninvolved limb (main effects, P<.001). CONCLUSION The persistence of limb asymmetries in men and women 6 months after ACLR indicates that current rehabilitation efforts are inadequate for some individuals following ACLR. PMID:25627155

Simultaneous Chandra and VLA Observations of the Transitional Millisecond Pulsar PSR J1023+0038: Anti-correlated X-Ray and Radio Variability

NASA Astrophysics Data System (ADS)

Bogdanov, Slavko; Deller, Adam T.; Miller-Jones, James C. A.; Archibald, Anne M.; Hessels, Jason W. T.; Jaodand, Amruta; Patruno, Alessandro; Bassa, Cees; D’Angelo, Caroline

2018-03-01

We present coordinated Chandra X-ray Observatory and Karl G. Jansky Very Large Array observations of the transitional millisecond pulsar PSR J1023+0038 in its low-luminosity accreting state. The unprecedented five hours of strictly simultaneous X-ray and radio continuum coverage for the first time unambiguously show a highly reproducible, anti-correlated variability pattern. The characteristic switches from the X-ray high mode into a low mode are always accompanied by a radio brightening with a duration that closely matches the X-ray low mode interval. This behavior cannot be explained by a canonical inflow/outflow accretion model where the radiated emission and the jet luminosity are powered by, and positively correlated with, the available accretion energy. We interpret this phenomenology as alternating episodes of low-level accretion onto the neutron star during the X-ray high mode that are interrupted by rapid ejections of plasma by the active rotation-powered pulsar, possibly initiated by a reconfiguration of the pulsar magnetosphere, that cause a transition to a less X-ray luminous mode. The observed anti-correlation between radio and X-ray luminosity has an additional consequence: transitional MSPs can make excursions into a region of the radio/X-ray luminosity plane previously thought to be occupied solely by black hole X-ray binary sources. This complicates the use of this luminosity relation for identifying candidate black holes, suggesting the need for additional discriminants when attempting to establish the true nature of the accretor.

Evaluating Experience-Based Geologic Field Instruction: Lessons Learned from A Large-Scale Eye-Tracking Experiment

NASA Astrophysics Data System (ADS)

Tarduno, J. A.; Walders, K.; Bono, R. K.; Pelz, J.; Jacobs, R.

2015-12-01

A course centered on experience-based learning in field geology has been offered ten times at the University of Rochester. The centerpiece of the course is a 10-day field excursion to California featuring a broad cross-section of the geology of the state, from the San Andreas Fault to Death Valley. Here we describe results from a large-scale eye-tracking experiment aimed at understanding how experts and novices acquire visual geologic information. One ultimate goal of the project is to determine whether expert gaze patterns can be quantified to improve the instruction of beginning geology students. Another goal is to determine if aspects of the field experience can be transferred to the classroom/laboratory. Accordingly, ultra-high resolution segmented panoramic images have been collected at key sites visited during the field excursion. We have found that strict controls are needed in the field to obtain meaningful data; this often involves behavior atypical of geologists (e.g. limiting the field of view prior to data collection and placing time limits on scene viewing). Nevertheless some general conclusions can be made from a select data set. After an initial quick search, experts tend to exhibit scanning behavior that appears to support hypothesis testing. Novice fixations appear to define a scattered search pattern and/or one distracted by geologic noise in a scene. Noise sources include modern erosion features and vegetation. One way to quantify noise is through the use of saliency maps. With the caveat that our expert data set is small, our preliminary analysis suggests that experts tend to exhibit top-down behavior (indicating hypothesis driven responses) whereas novices show bottom-up gaze patterns, influenced by more salient features in a scene. We will present examples and discuss how these observations might be used to improve instruction.

Transmembrane protein CD93 diffuses by a continuous time random walk.

NASA Astrophysics Data System (ADS)

Goiko, Maria; de Bruyn, John; Heit, Bryan

Molecular motion within the cell membrane is a poorly-defined process. In this study, we characterized the diffusion of the transmembrane protein CD93. By careful analysis of the dependence of the ensemble-averaged mean squared displacement (EA-MSD, r2) on time t and the ensemble-averaged, time-averaged MSD (EA-TAMSD, δ2) on lag time τ and total measurement time T, we showed that the motion of CD93 is well-described by a continuous-time random walk (CTRW). CD93 tracks were acquired using single particle tracking. The tracks were classified as confined or free, and the behavior of the MSD analyzed. EA-MSDs of both populations grew non-linearly with t, indicative of anomalous diffusion. Their EA-TAMSDs were found to depend on both τ and T, indicating non-ergodicity. Free molecules had r2 tα and δ2 (τ /T 1 - α) , with α 0 . 5 , consistent with a CTRW. Mean maximal excursion analysis supported this result. Confined CD93 had r2 t0 and δ2 (τ / T) α , with α 0 . 3 , consistent with a confined CTRW. CTRWs are described by a series of random jumps interspersed with power-law distributed waiting times, and may arise due to the interactions of CD93 with the endocytic machinery. NSERC.

High voltage stability of LiCoO2 particles with a nano-scale Lipon coating

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

Kim, Yoongu; Veith, Gabriel M; Nanda, Jagjit

2011-01-01

For high-voltage cycling of rechargeable Li batteries, a nano-scale amorphous Li-ion conductor, lithium phosphorus oxynitride (Lipon), has been coated on surfaces of LiCoO{sub 2} particles by combining a RF-magnetron sputtering technique and mechanical agitation of LiCoO{sub 2} powders. LiCoO{sub 2} particles coated with 0.36 wt% ({approx}1 nm thick) of the amorphous Lipon, retain 90% of their original capacity compared to non-coated cathode materials that retain only 65% of their original capacity after more than 40 cycles in the 3.0-4.4 V range with a standard carbonate electrolyte. The reason for the better high-voltage cycling behavior is attributed to reduction in themore » side reactions that cause increase of the cell resistance during cycling. Further, Lipon coated particles are not damaged, whereas uncoated particles are badly cracked after cycling. Extending the charge of Lipon-coated LiCoO{sub 2} to higher voltage enhances the specific capacity, but more importantly the Lipon-coated material is also more stable and tolerant of high voltage excursions. A drawback of Lipon coating, particularly as thicker films are applied to cathode powders, is the increased electronic resistance that reduces the power performance.« less

Experimental investigation of cyclic thermomechanical deformation in torsion

NASA Technical Reports Server (NTRS)

Ellis, John R.; Castelli, Michael G.; Bakis, Charles E.

1992-01-01

An investigation of thermomechanical testing and deformation behavior of tubular specimens under torsional loading is described. Experimental issues concerning test accuracy and control specific to thermomechanical loadings under a torsional regime are discussed. A series of shear strain-controlled tests involving the nickel-base superalloy Hastelloy X were performed with various temperature excursions and compared to similar thermomechanical uniaxial tests. The concept and use of second invariants of the deviatoric stress and strain tensors as a means of comparing uniaxial and torsional specimens is also briefly presented and discussed in light of previous thermomechanical tests conducted under uniaxial conditions.

Speckle tracking as a method to measure hemidiaphragm excursion.

PubMed

Goutman, Stephen A; Hamilton, James D; Swihart, Blake; Foerster, Bradley; Feldman, Eva L; Rubin, Jonathan M

2017-01-01

Diaphragm excursion measured via ultrasound may be an important imaging outcome measure of respiratory function. We developed a new method for measuring diaphragm movement and compared it to the more traditional M-mode method. Ultrasound images of the right and left hemidiaphragms were collected to compare speckle tracking and M-mode measurements of diaphragm excursion. Speckle tracking was performed using EchoInsight (Epsilon Imaging, Ann Arbor, Michigan). Six healthy subjects without a history of pulmonary diseases were included in this proof-of-concept study. Speckle tracking of the diaphragm is technically possible. Unlike M-mode, speckle tracking carries the advantage of reliable visualization and measurement of the left hemidiaphragm. Speckle tracking accounted for diaphragm movement simultaneously in the cephalocaudad and mediolateral directions, unlike M-mode, which is 1-dimensional. Diaphragm speckle tracking may represent a novel, more robust method for measuring diaphragm excursion, especially for the left hemidiaphragm. Muscle Nerve 55: 125-127, 2017. © 2016 Wiley Periodicals, Inc.

Geomagnetic paleointensities from excursion sequences in lavas on Oahu, Hawaii

USGS Publications Warehouse

Coe, Robert S.; Gromme, Sherman; Mankinen, Edward A.

1984-01-01

Paleomagnetic data demonstrating three late Tertiary excursions in the direction of the geomagnetic field recorded in sequences of basaltic lavas on the island of Oahu, Hawaii were published by R. R. Doell and G. B. Dalrymple in 1973. We have determined geomagnetic paleointensities by the Thelliers' method for 14 lavas from the three sites. During these experiments, considerable difficulty was encountered because of the presence of titanomaghemite in many lavas and the contamination of natural remanent magnetization by lightning in many others. Moreover, we often observed the production of spurious high‐temperature chemical remanent magnetization during the Thellier experiments. An analysis of this particularly troublesome problem is presented. Two of the sites showed low paleointensities associated with angular departures of the paleomagnetic field direction from that of a geocentric axial dipole, which suggests that these excursions represent aborted reversals or fragments of reversals. At the third site, however, the paleointensity did not become low as the field diverged. This excursion may reflect the variation of a large nondipole source near Hawaii.

Illness and injury to students on a school excursion to Peru.

PubMed

Shaw, Marc T M; Harding, Elizabeth; Leggat, Peter A

2014-01-01

School-organized travels abroad provide an opportunity for students to undertake supervised travel that reinforces scholastic study of various geographical locations under the direction and protection of experienced tour leaders and health professional support. Little is known concerning the nature of illnesses and injuries occurring on overseas school excursions. This study was designed to investigate the prevalence of injury and illness suffered by older teenagers on a school excursion to South America. In 2010, the school's tour physician (EH) diagnosed and recorded all illnesses and injuries among 29 school girls and 6 accompanying adults on a school excursion to Peru. Information recorded included age, sex, the nature of the presenting illness, number of days into the tour, the assessment of the condition, and the treatment employed during the excursion's field phase of 21 days. A total of 32 (91%) travelers sought medical advice at least once for a total of 371 consultations, resulting in 153 separate diagnoses. The mean age of the students was 16 years with six adults accompanying the students being significantly older. Primary illnesses diagnosed were related to the following systems and conditions: gastrointestinal (58, 37%), respiratory (25, 16%), altitude sickness (19, 12%), genitourinary (8, 5%), dermatological (10, 7%), trauma (7, 5%), neurological (7, 5%), anxiety or psychological adjustment (7, 5%), adverse drug reactions (4, 3%), and musculoskeletal (5, 3%). The most commonly used medications were antidiarrheal and antiemetic medication. There were six accidents during the journey resulting in minor soft-tissue injuries. There were no deaths or other major accidents requiring emergency evacuation or hospitalization. On this school excursion, the health problems encountered were consistent with those reported for other specialized tours, including expeditions and premium tours, although altitude illness needs to be carefully planned for in tours to higher elevation destinations as in South America. As well as being part of the service provided to the school students, the inclusion of a physician with appropriate medical supplies for this tour increased the independence of the travel group. A proposed medical kit for such an excursion is presented. © 2014 International Society of Travel Medicine.

Occupant kinematics in low-speed frontal sled tests: Human volunteers, Hybrid III ATD, and PMHS.

PubMed

Beeman, Stephanie M; Kemper, Andrew R; Madigan, Michael L; Franck, Christopher T; Loftus, Stephen C

2012-07-01

A total of 34 dynamic matched frontal sled tests were performed, 17 low (2.5g, Δv=4.8kph) and 17 medium (5.0g, Δv=9.7kph), with five male human volunteers of approximately 50th percentile height and weight, a Hybrid III 50th percentile male ATD, and three male PMHS. Each volunteer was exposed to two impulses at each severity, one relaxed and one braced prior to the impulse. A total of four tests were performed at each severity with the ATD and one trial was performed at each severity with each PMHS. A Vicon motion analysis system, 12 MX-T20 2 megapixel cameras, was used to quantify subject 3D kinematics (±1mm) (1kHz). Excursions of select anatomical regions were normalized to their respective initial positions and compared by test condition and between subject types. The forward excursions of the select anatomical regions generally increased with increasing severity. The forward excursions of relaxed human volunteers were significantly larger than those of the ATD for nearly every region at both severities. The forward excursions of the upper body regions of the braced volunteers were generally significantly smaller than those of the ATD at both severities. Forward excursions of the relaxed human volunteers and PMHSs were fairly similar except the head CG response at both severities and the right knee and C7 at the medium severity. The forward excursions of the upper body of the PMHS were generally significantly larger than those of the braced volunteers at both severities. Forward excursions of the PMHSs exceeded those of the ATD for all regions at both severities with significant differences within the upper body regions. Overall human volunteers, ATD, and PMHSs do not have identical biomechanical responses in low-speed frontal sled tests but all contribute valuable data that can be used to refine and validate computational models and ATDs used to assess injury risk in automotive collisions. Copyright © 2012 Elsevier Ltd. All rights reserved.

Invariance in the recurrence of large returns and the validation of models of price dynamics

NASA Astrophysics Data System (ADS)

Chang, Lo-Bin; Geman, Stuart; Hsieh, Fushing; Hwang, Chii-Ruey

2013-08-01

Starting from a robust, nonparametric definition of large returns (“excursions”), we study the statistics of their occurrences, focusing on the recurrence process. The empirical waiting-time distribution between excursions is remarkably invariant to year, stock, and scale (return interval). This invariance is related to self-similarity of the marginal distributions of returns, but the excursion waiting-time distribution is a function of the entire return process and not just its univariate probabilities. Generalized autoregressive conditional heteroskedasticity (GARCH) models, market-time transformations based on volume or trades, and generalized (Lévy) random-walk models all fail to fit the statistical structure of excursions.

Immediate Effects of a Single Session of Motor Skill Training on the Lumbar Movement Pattern During a Functional Activity in People With Low Back Pain: A Repeated-Measures Study.

PubMed

Marich, Andrej V; Lanier, Vanessa M; Salsich, Gretchen B; Lang, Catherine E; Van Dillen, Linda R

2018-04-06

People with low back pain (LBP) may display an altered lumbar movement pattern of early lumbar motion compared to people with healthy backs. Modifying this movement pattern during a clinical test decreases pain. It is unknown whether similar effects would be seen during a functional activity. The objective of this study is was to examine the lumbar movement patterns before and after motor skill training, effects on pain, and characteristics that influenced the ability to modify movement patterns. The design consisted of a repeated-measures study examining early-phase lumbar excursion in people with LBP during a functional activity test. Twenty-six people with chronic LBP received motor skill training, and 16 people with healthy backs were recruited as a reference standard. Twenty minutes of motor skill training to decrease early-phase lumbar excursion during the performance of a functional activity were used as a treatment intervention. Early-phase lumbar excursion was measured before and after training. Participants verbally reported increased pain, decreased pain, or no change in pain during performance of the functional activity test movement in relation to their baseline pain. The characteristics of people with LBP that influenced the ability to decrease early-phase lumbar excursion were examined. People with LBP displayed greater early-phase lumbar excursion before training than people with healthy backs (LBP: mean = 11.2°, 95% CI = 9.3°-13.1°; healthy backs: mean = 7.1°, 95% CI = 5.8°-8.4°). Following training, the LBP group showed a decrease in the amount of early-phase lumbar excursion (mean change = 4.1°, 95% CI = 2.4°-5.8°); 91% of people with LBP reported that their pain decreased from baseline following training. The longer the duration of LBP (β = - 0.22) and the more early-phase lumbar excursion before training (β = - 0.82), the greater the change in early-phase lumbar excursion following training. The long-term implications of modifying the movement pattern and whether the decrease in pain attained was clinically significant are unknown. People with LBP were able to modify their lumbar movement pattern and decrease their pain with the movement pattern within a single session of motor skill training.

Engaging students in research learning experiences through hydrology field excursions and short films

NASA Astrophysics Data System (ADS)

Ewen, Tracy; Seibert, Jan

2015-04-01

One of the best ways to engage students and instill enthusiasm for hydrology is to expose them to hands-on learning. A focus on hydrology field research can be used to develop context-rich and active learning, and help solidify idealized learning where students are introduced to individual processes through textbook examples, often neglecting process interactions and an appreciation for the complexity of the system. We introduced a field course where hydrological measurement techniques are used to study processes such as snow hydrology and runoff generation, while also introducing students to field research and design of their own field project. Additionally, we produced short films of each of these research-based field excursions, with in-house film expertise. These films present a short overview of field methods applied in alpine regions and will be used for our larger introductory hydrology courses, exposing students to field research at an early stage, and for outreach activities, including for potential high school students curious about hydrology. In the field course, students design a low-budget experiment with the aim of going through the different steps of a 'real' scientific project, from formulating the research question to presenting their results. During the field excursions, students make discharge measurements in several alpine streams with a salt tracer to better understand the spatial characteristics of an alpine catchment, where source waters originate and how they contribute to runoff generation. Soil moisture measurements taken by students in this field excursion were used to analyze spatial soil moisture patterns in the alpine catchment and subsequently used in a publication. Another field excursion repeats a published experiment, where preferential soil flow paths are studied using a tracer and compared to previously collected data. For each field excursion, observational data collected by the students is uploaded to an online database we developed, where students can also retrieve data from past excursions to further analyze and compare their data. At each of the field sites, weather stations were installed and a webviewer allows access to realtime data from data loggers, allowing students to explore how processes relate to climatic conditions. Together, these field excursions give students the necessary tools they will need to carry out field research of their own in future projects, whether in academia or industry, while the short films give potential or first-year students an impression of what hydrology is all about and hopefully inspire them to become future hydrologists.

A gaussian model for simulated geomagnetic field reversals

NASA Astrophysics Data System (ADS)

Wicht, Johannes; Meduri, Domenico G.

2016-10-01

Field reversals are the most spectacular events in the geomagnetic history but remain little understood. Here we explore the dipole behaviour in particularly long numerical dynamo simulations to reveal statistically significant conditions required for reversals and excursions to happen. We find that changes in the axial dipole moment behaviour are crucial while the equatorial dipole moment plays a negligible role. For small Rayleigh numbers, the axial dipole always remains strong and stable and obeys a clearly Gaussian probability distribution. Only when the Rayleigh number is increased sufficiently the axial dipole can reverse and its distribution becomes decisively non-Gaussian. Increased likelihoods around zero indicate a pronounced lingering in a new low dipole moment state. Reversals and excursions can only happen when axial dipole fluctuations are large enough to drive the system from the high dipole moment state assumed during stable polarity epochs into the low dipole moment state. Since it is just a matter of chance which polarity is amplified during dipole recovery, reversals and grand excursions, i.e. excursions during which the dipole assumes reverse polarity, are equally likely. While the overall reversal behaviour seems Earth-like, a closer comparison to palaeomagnetic findings suggests that the simulated events last too long and that grand excursions are too rare. For a particularly large Ekman number we find a second but less Earth-like type of reversals where the total field decays and recovers after a certain time.

Influence of hip and knee osteoarthritis on dynamic postural control parameters among older fallers.

PubMed

Mat, Sumaiyah; Ng, Chin Teck; Tan, Maw Pin

2017-03-06

To compare the relationship between postural control and knee and hip osteoarthritis in older adults with and without a history of falls. Fallers were those with ≥ 2 falls or 1 injurious fall over 12 months. Non-fallers were volunteers with no falls in the past year. Radiological evidence of osteoarthritis with no reported symptoms was considered "asymptomatic osteoarthritis", while "symptomatic osteoarthritis" was defined as radiographic osteoarthritis with pain or stiffness. Dynamic postural control was quantified with the limits of stability test measured on a balance platform (Neurocom® Balancemaster, California, USA). Parameters assessed were end-point excursion, maximal excursion, and directional control. A total of 102 older individuals, mean age 73 years (standard deviation 5.7) years were included. The association between falls and poor performance in maximal excursion and directional control was confounded by age and comorbidities. In the same linear equation model with falls, symptomatic osteoarthritis remained independently associated with poor end-point excursion (β-coefficient (95% confidence interval) -6.80 (-12.14 to -1.42)). Poor performance in dynamic postural control (maximal excursion and directional control) among fallers was not accounted for by hip/knee osteoarthritis, but was confounded by old age and comorbidities. Loss of postural control due to hip/knee osteoarthritis is not a risk factor for falls among community-dwelling older adults.

Carbon isotopic shift and its cause at the Wuchiapingian-Changhsingian boundary in the Upper Permian at the Zhaojiaba section, South China: Evidences from multiple geochemical proxies

NASA Astrophysics Data System (ADS)

Wei, Hengye; Yu, Hao; Wang, Jianguo; Qiu, Zhen; Xiang, Lei; Shi, Guo

2015-06-01

The Late Permian environmental change, connecting the Guadalupian-Lopingian (G-L) (Middle-Upper Permian) boundary mass extinction and the Permain-Triassic (P-Tr) boundary mass extinction, has attracted more and more attentions. A significant negative shift for carbon isotope had been found at the Wuchiapingian-Changhsingian (W-C) boundary in the Upper Permian recently. However, the cause(s) of this negative excursion is still unknown. To resolve this problem, we analyzed the bulk organic carbon isotope, total organic carbon (TOC) content, pyritic sulfur (Spy) content, major element concentrations, and molecular organic biomarkers in the Wujiaping and Dalong formations in the Upper Permian from the Zhaojiaba section in western Hubei province, South China. Our results show that (1) there was a significant negative excursion in organic carbon isotopes at the W-C boundary and again a negative excursion at the top of Changhsingian stage; (2) the significant negative excursion at the W-C boundary was probably a global signal and mainly caused by the low primary productivity; and (3) the negative carbon isotope excursion at the top of Changhsingian was probably caused by the Siberian Traps eruptions. A decline in oceanic primary productivity at the W-C boundary probably represents a disturbance of the marine food web, leading to a vulnerable ecosystem prior to the P-Tr boundary mass extinction.

An experimental apparatus to simulate body-powered prosthetic usage: Development and preliminary evaluation.

PubMed

Gao, Fan; Rodriguez, Johanan; Kapp, Susan

2016-06-01

Harness fitting in the body-powered prosthesis remains more art than science due to a lack of consistent and quantitative evaluation. The aim of this study was to develop a mechanical, human-body-shaped apparatus to simulate body-powered upper limb prosthetic usage and evaluate its capability of quantitative examination of harness configuration. The apparatus was built upon a torso of a wooden mannequin and integrated major mechanical joints to simulate terminal device operation. Sensors were used to register cable tension, cable excursion, and grip force simultaneously. The apparatus allowed the scapula to move up to 127 mm laterally and the load cell can measure the cable tension up to 445 N. Our preliminary evaluation highlighted the needs and importance of investigating harness configurations in a systematic and controllable manner. The apparatus allows objective, systematic, and quantitative evaluation of effects of realistic harness configurations and will provide insightful and working knowledge on harness fitting in upper limb amputees using body-powered prosthesis. © The International Society for Prosthetics and Orthotics 2015.

Application of Raman spectroscopy technology to studying Sudan I

NASA Astrophysics Data System (ADS)

Li, Gang; Zhang, Guoping; Chen, Chen

2006-06-01

Being an industrial dye, the Sudan I may have a toxic effect after oral intake on the body, and has recently been shown to cause cancer in rats, mice and rabbits. Because China and some other countries have detected the Sudan I in samples of the hot chilli powder and the chilli products, it is necessary to study the characteristics of this dye. As one kind of molecule scattering spectroscopy, Raman spectroscopy is characterized by the frequency excursion caused by interactions of molecules and photons. The frequency excursion reflects the margin between certain two vibrational or rotational energy states, and shows the information of the molecule. Because Raman spectroscopy can provides quick, easy, reproducible, and non-destructive analysis, both qualitative and quantitative, with no sample preparation required, Raman spectroscopy has been a particularly promising technique for analyzing the characteristics and structures of molecules, especially organic ones. Now, it has a broad application in biological, chemical, environmental and industrial applications. This paper firstly introduces Sudan I dye and the Raman spectroscopy technology, and then describes its application to the Sudan I. Secondly, the fingerprint spectra of the Sudan I are respectively assigned and analyzed in detail. Finally, the conclusion that the Raman spectroscopy technology is a powerful tool to determine the Sudan I is drawn.

Ultra-High Temperature Steam Corrosion of Complex Silicates for Nuclear Applications: A Computational Study

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

Rashkeev, Sergey N.; Glazoff, Michael V.; Tokuhiro, Akira

2014-01-01

Stability of materials under extreme conditions is an important issue for safety of nuclear reactors. Presently, silicon carbide (SiC) is being studied as a cladding material candidate for fuel rods in boiling-water and pressurized water-cooled reactors (BWRs and PWRs) that would substitute or modify traditional zircaloy materials. The rate of corrosion of the SiC ceramics in hot vapor environment (up to 2200 degrees C) simulating emergency conditions of light water reactor (LWR) depends on many environmental factors such as pressure, temperature, viscosity, and surface quality. Using the paralinear oxidation theory developed for ceramics in the combustion reactor environment, we estimatedmore » the corrosion rate of SiC ceramics under the conditions representing a significant power excursion in a LWR. It was established that a significant time – at least 100 h – is required for a typical SiC braiding to significantly degrade even in the most aggressive vapor environment (with temperatures up to 2200 °C) which is possible in a LWR at emergency condition. This provides evidence in favor of using the SiC coatings/braidings for additional protection of nuclear reactor rods against off-normal material degradation during power excursions or LOCA incidents. Additionally, we discuss possibilities of using other silica based ceramics in order to find materials with even higher corrosion resistance than SiC. In particular, we found that zircon (ZrSiO4) is also a very promising material for nuclear applications. Thermodynamic and first-principles atomic-scale calculations provide evidence of zircon thermodynamic stability in aggressive environments at least up to 1535 degrees C.« less

Differential effects of power training versus functional task practice on compensation and restoration of arm function after stroke.

PubMed

Corti, Manuela; McGuirk, Theresa E; Wu, Samuel S; Patten, Carolynn

2012-09-01

Improved upper-extremity (UE) movement with stroke rehabilitation may involve restoration of more normal or development of compensatory movement patterns. The authors investigated the differential effects of functional task practice (FTP) and dynamic resistance training (POWER) on clinical function and reaching kinematics in an effort to distinguish between mechanisms of gains. A total of 14 hemiparetic individuals were randomly assigned to 10 weeks of either FTP or POWER and then crossed over to 10 weeks of the alternate treatment. Treatment order A was FTP followed by POWER, whereas treatment order B was POWER followed by FTP. Evaluation before and after each treatment block included a battery of clinical evaluations and kinematics of paretic UE functional reach to grasp. Both FTP and POWER improved movement accuracy, as revealed by a shift toward normal, including fewer submovements and reduced reach-path ratio. However, active range of motion revealed differential treatment effects. Shoulder flexion and elbow extension decreased with FTP and were associated with increased trunk displacement. In contrast, shoulder flexion and elbow extension excursion increased with POWER and were associated with significantly reduced trunk displacement. Treatment order B (POWER followed by FTP) revealed greater overall improvements. FTP increases compensatory movement patterns to improve UE function. POWER leads to more normal movement patterns. POWER prior to FTP may enhance the benefits of repetitive task practice.

46 CFR 176.204 - Permit to carry excursion party.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., survival craft, life jacket, fire safety, and manning standards applicable to a vessel in the service for... may carry, the crew required, any additional lifesaving or safety equipment required, the route for... waive the applicable minimum safety standards when issuing an excursion permit. In particular, a vessel...

46 CFR 176.204 - Permit to carry excursion party.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., survival craft, life jacket, fire safety, and manning standards applicable to a vessel in the service for... may carry, the crew required, any additional lifesaving or safety equipment required, the route for... waive the applicable minimum safety standards when issuing an excursion permit. In particular, a vessel...

46 CFR 176.204 - Permit to carry excursion party.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., survival craft, life jacket, fire safety, and manning standards applicable to a vessel in the service for... may carry, the crew required, any additional lifesaving or safety equipment required, the route for... waive the applicable minimum safety standards when issuing an excursion permit. In particular, a vessel...

40 CFR 63.1334 - Parameter monitoring levels and excursions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... period for the storage vessel. (ii) If the monitoring plan does not specify monitoring a parameter and... semiannually or quarterly. The first semiannual period is the 6-month period starting the date the Notification... period—two excused excursions. (6) For the sixth and all subsequent semiannual periods—one excused...

Extraordinary Activity in the BL Lac Object OJ 287

NASA Astrophysics Data System (ADS)

Hughes, P. A.; Aller, H. D.; Aller, M. F.

We present the results of a wavelet transform analysis of data for the BL Lac object OJ 287 acquired as part of the UMRAO variability program. We find clear evidence for a persistent modulation of the total flux and polarization with period 1.66 years, and for another signal that dominates activity in the 1980s with period 1.12 years. It appears that the longer time scale periodicity is associated with an otherwise quiescent jet, and the shorter time scale activity is associated with the passage of a shock, or shocks. The periodic behavior in polarization exhibits excursions in U which correspond to a direction 45circ from the VLBI jet axis. This behavior suggests a small amplitude, cyclic variation in the flow direction in that part of the flow that dominates cm-wavelength emission.

The Hirnantian δ13C Positive Excursion in the Nabiullino Section (South Urals)

NASA Astrophysics Data System (ADS)

Yakupov, R. R.; Mavrinskaya, T. M.; Smoleva, I. V.

2018-02-01

The upper Sandbian, Katian, and Hirnantian complexes of conodonts in the upper Ordovician section of the western slope of the Southern Urals near the village of Nabiullino were studied. The δ13C positive excursion with a maximum of 3.3‰ associated with the global Hirnantian isotopic event, HICE, was fixed for the first time. This excursion shows the beginning of the Hirnantian stage in the terrigenous-carbonate section of the upper Ordovician in the Southern Urals. It coincides with the first occurrence of the Hirnantian conodont species of Gamachignathus ensifer and the conodonts of shallow-water biophacies, Aphelognathus-Ozarkodina, reflecting the global glacio-eustatic event.

Kilovoltage Intrafraction Monitoring for Prostate Intensity Modulated Arc Therapy: First Clinical Results

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

Ng, Jin Aun; Institute of Medical Physics, School of Physics, University of Sydney, New South Wales; Booth, Jeremy T.

2012-12-01

Purpose: Most linear accelerators purchased today are equipped with a gantry-mounted kilovoltage X-ray imager which is typically used for patient imaging prior to therapy. A novel application of the X-ray system is kilovoltage intrafraction monitoring (KIM), in which the 3-dimensional (3D) tumor position is determined during treatment. In this paper, we report on the first use of KIM in a prospective clinical study of prostate cancer patients undergoing intensity modulated arc therapy (IMAT). Methods and Materials: Ten prostate cancer patients with implanted fiducial markers undergoing conventionally fractionated IMAT (RapidArc) were enrolled in an ethics-approved study of KIM. KIM involves acquiringmore » kV images as the gantry rotates around the patient during treatment. Post-treatment, markers in these images were segmented to obtain 2D positions. From the 2D positions, a maximum likelihood estimation of a probability density function was used to obtain 3D prostate trajectories. The trajectories were analyzed to determine the motion type and the percentage of time the prostate was displaced {>=}3, 5, 7, and 10 mm. Independent verification of KIM positional accuracy was performed using kV/MV triangulation. Results: KIM was performed for 268 fractions. Various prostate trajectories were observed (ie, continuous target drift, transient excursion, stable target position, persistent excursion, high-frequency excursions, and erratic behavior). For all patients, 3D displacements of {>=}3, 5, 7, and 10 mm were observed 5.6%, 2.2%, 0.7% and 0.4% of the time, respectively. The average systematic accuracy of KIM was measured at 0.46 mm. Conclusions: KIM for prostate IMAT was successfully implemented clinically for the first time. Key advantages of this method are (1) submillimeter accuracy, (2) widespread applicability, and (3) a low barrier to clinical implementation. A disadvantage is that KIM delivers additional imaging dose to the patient.« less

Multicultural Group Work on Field Excursions to Promote Student Teachers' Intercultural Competence

ERIC Educational Resources Information Center

Brendel, Nina; Aksit, Fisun; Aksit, Selahattin; Schrüfer, Gabriele

2016-01-01

As a response to the intercultural challenges of Geography Education, this study seeks to determine factors fostering intercultural competence of student teachers. Based on a one-week multicultural field excursion of eight German and eight Turkish students in Kayseri (Turkey) on Education for Sustainable Development, we used qualitative interviews…

Enabling the Development of Student Teacher Professional Identity through Vicarious Learning during an Educational Excursion

ERIC Educational Resources Information Center

Steenekamp, Karen; van der Merwe, Martyn; Mehmedova, Aygul Salieva

2018-01-01

This paper explores the views of student teachers who were provided vicarious learning opportunities during an educational excursion, and how the learning enabled them to develop their teacher professional identity. This qualitative research study, using a social-constructivist lens highlights how vicarious learning influenced student teachers'…

Non-invasive measurement of pulse wave velocity using transputer-based analysis of Doppler flow audio signals.

PubMed

Stewart, W R; Ramsey, M W; Jones, C J

1994-08-01

A system for the measurement of arterial pulse wave velocity is described. A personal computer (PC) plug-in transputer board is used to process the audio signals from two pocket Doppler ultrasound units. The transputer is used to provide a set of bandpass digital filters on two channels. The times of excursion of power through thresholds in each filter are recorded and used to estimate the onset of systolic flow. The system does not require an additional spectrum analyser and can work in real time. The transputer architecture provides for easy integration into any wider physiological measurement system.

Predictive momentum management for the Space Station

NASA Technical Reports Server (NTRS)

Hatis, P. D.

1986-01-01

Space station control moment gyro momentum management is addressed by posing a deterministic optimization problem with a performance index that includes station external torque loading, gyro control torque demand, and excursions from desired reference attitudes. It is shown that a simple analytic desired attitude solution exists for all axes with pitch prescription decoupled, but roll and yaw coupled. Continuous gyro desaturation is shown to fit neatly into the scheme. Example results for pitch axis control of the NASA power tower Space Station are shown based on predictive attitude prescription. Control effector loading is shown to be reduced by this method when compared to more conventional momentum management techniques.

Glycemic excursions are positively associated with changes in duration of asymptomatic hypoglycemia after treatment intensification in patients with type 2 diabetes.

PubMed

Wang, Jun-Sing; Lee, I-Te; Lee, Wen-Jane; Lin, Shi-Dou; Su, Shih-Li; Tu, Shih-Te; Tseng, Yao-Hsien; Lin, Shih-Yi; Sheu, Wayne Huey-Herng

2016-03-01

The aim of this study was to examine the association between glycemic excursions and duration of hypoglycemia after treatment intensification in patients with type 2 diabetes (T2D). Patients with T2D on oral anti-diabetes drug (OAD) with glycated hemoglobin (HbA1c) of 7.0-11.0% were switched to metformin monotherapy (500 mg thrice daily) for 8 weeks, followed by randomization to either glibenclamide or acarbose as add-on treatment for 16 weeks. Glycemic excursions were assessed as mean amplitude of glycemic excursions (MAGE) with 72-h ambulatory continuous glucose monitoring (CGM) before randomization and at the end of study. Hypoglycemia was defined as sensor glucose level of less than 60 mg/dl in two or more consecutive readings from CGM. A total of 50 patients (mean age 53.5 ± 8.2 years, male 48%, mean baseline HbA1c 8.4 ± 1.2%) were analyzed. Duration of hypoglycemia significantly increased after treatment with glibenclamide (from 5.5 ± 13.8 to 18.8 ± 35.8 min/day, p=0.041), but not with acarbose (from 2.9 ± 10.9 to 14.7 ± 41.9 min/day, p=0.114). Post treatment MAGE was positively associated with change from baseline in duration of hypoglycemia after treatment with either glibenclamide (β coefficient 0.345, p=0.036) or acarbose (β coefficient 0.674, p=0.046). The association remained significant after multivariate adjustment (p<0.05 for all models). Post treatment glycemic excursions are associated with changes in duration of hypoglycemia after treatment intensification with OAD in patients with T2D. Glycemic excursions should be an important treatment target for T2D to reduce the risk of hypoglycemia. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Disk Disruptions and X-ray Intensity Excursions in Cyg X-2, LMC X-3 and Cyg X-3

NASA Astrophysics Data System (ADS)

Boyd, P. T.; Smale, A. P.

2001-05-01

The RXTE All Sky Monitor soft X-ray light curves of many X-ray binaries show long-term intensity variations (a.k.a "superorbital periodicities") that have been ascribed to precession of a warped, tilted accretion disk around the X-ray source. We have found that the excursion times between X-ray minima in Cyg X-2 can be characterized as a series of integer multiples of the 9.8 binary orbital period, (as opposed to the previously reported stable 77.7 day single periodicity, or a single modulation whose period changes slowly with time). While the data set is too short for a proper statistical analysis, it is clear that the length of any given intensity excursion cannot be used to predict the next (integer) excursion length in the series. In the black hole candidate system LMC X-3, the excursion times are shown to be related to each other by rational fractions. We find that the long term light curve of the unusual galactic X-ray jet source Cyg X-3 can also be described as a series of intensity excursions related to each other by integer multiples of a fundamental underlying clock. In the latter cases, the clock is apparently not related to the known binary periods. A unified physical model, involving both an inclined accretion disk and a fixed-probability disk disruption mechanism is presented, and compared with three-body scattering results. Each time the disk passes through the orbital plane it experiences a fixed probability P that it will disrupt. This model has testable predictions---the distribution of integers should resemble that of an atomic process with a characteristic half life. Further analysis can support or refute the model, and shed light on what system parameters effectively set the value of P.

Knee Joint Contact Mechanics during Downhill Gait and its Relationship with Varus/Valgus Motion and Muscle Strength in Patients with Knee Osteoarthritis

PubMed Central

Farrokhi, Shawn; Voycheck, Carrie A.; Gustafson, Jonathan A.; Fitzgerald, G. Kelley; Tashman, Scott

2015-01-01

Objective The objective of this exploratory study was to evaluate tibiofemoral joint contact point excursions and velocities during downhill gait and assess the relationship between tibiofemoral joint contact mechanics with frontal-plane knee joint motion and lower extremity muscle weakness in patients with knee osteoarthritis (OA). Methods Dynamic stereo X-ray was used to quantify tibiofemoral joint contact mechanics and frontal-plane motion during the loading response phase of downhill gait in 11 patients with knee OA and 11 control volunteers. Quantitative testing of the quadriceps and the hip abductor muscles was also performed. Group differences in contact mechanics and frontal-plane motion excursions were compared using analysis of covariance with adjustments for body mass index. Differences in strength were compared using independent sample t-tests. Additionally, linear associations between contact mechanics with frontal-plane knee motion and muscle strength were evaluated using Pearson's correlation coefficients. Results Patients with knee OA demonstrated larger medial/lateral joint contact point excursions (p<0.02) and greater heel-strike joint contact point velocities (p<0.05) for the medial and lateral compartments compared to the control group. The peak medial/lateral joint contact point velocity of the medial compartment was also greater for patients with knee OA compared to their control counterparts (p=0.02). Additionally, patients with knee OA demonstrated significantly increased frontal-plane varus motion excursions (p<0.01) and greater quadriceps and hip abductor muscle weakness (p=0.03). In general, increased joint contact point excursions and velocities in patients with knee OA were linearly associated with greater frontal-plane varus motion excursions (p<0.04) but not with quadriceps or hip abductor strength. Conclusion Altered contact mechanics in patients with knee OA may be related to compromised frontal-plane joint stability but not with deficits in muscle strength. PMID:27030846

Nateglinide and acarbose are comparably effective reducers of postprandial glycemic excursions in chinese antihyperglycemic agent-naive subjects with type 2 diabetes.

PubMed

Zhou, Jian; Li, Hong; Zhang, Xiuzhen; Peng, Yongde; Mo, Yifei; Bao, Yuqian; Jia, Weiping

2013-06-01

Recent studies have identified postprandial glycemic excursions as risk factors for diabetes complications. This study aimed to compare the effects of nateglinide and acarbose treatments on postprandial glycemic excursions in Chinese subjects with type 2 diabetes. This was a multicenter, open-label, randomized, active-controlled, parallel-group study. One hundred three antihyperglycemic agent-naive subjects with type 2 diabetes (hemoglobin A1c range, 6.5-9.0%) were prospectively recruited from four hospitals in China. The intervention was nateglinide (120 mg three times a day) or acarbose (50 mg three times a day) therapy for 2 weeks. A continuous glucose monitoring system was used to calculate the incremental area under the curve of postprandial blood glucose (AUCpp), the incremental glucose peak (IGP), mean amplitude of glycemic excursions, SD of blood glucose, the mean of daily differences, and 24-h mean blood glucose (MBG). Subjects' serum glycated albumin and the plasma insulin levels were also analyzed. Both agents caused significant reductions on AUCpp and IGP. Similarly, both treatment groups showed significant improvements in the intra- and interday glycemic excursions, as well as the 24-h MBG and serum glycated albumin compared with baseline (P<0.001). However, neither of the agents produced a significantly better effect (P>0.05). Moreover, the nateglinide-treated group had significantly increased insulin levels at 30 min and at 120 min after a standard meal compared with baseline, whereas the acarbose-treated group decreased. No serious adverse events occurred in either group. The rates of hypoglycemic episodes were comparable in the two groups, and no severe hypoglycemic episode occurred in either group. Nateglinide and acarbose were comparably effective in reducing postprandial glycemic excursions in antihyperglycemic agent-naive Chinese patients with type 2 diabetes, possibly through different pathophysiological mechanisms.

Is the Earth's magnetic field heading for a flip? Hints from the past

NASA Astrophysics Data System (ADS)

Laj, C. E.; Kissel, C.

2017-12-01

The magnitude of the Earth's dipole magnetic field has decreased significantly over the last centuries at a mean rate of 16 nT/y. This decrease, which correlates with the growth of the South Atlantic Anomaly (SAA) therefore occurs at a rate which is about 10 times larger than expected from a free Ohmic decay process. This situation has led to speculations that an attempt to a reversal or a geomagnetic excursion might be underway. We investigate this hypothesis by examining past geomagnetic instabilities, focussing on the well documented Laschamp and Mono Lake excursions. We have selected high accumulation sedimentary records with very precise age model, leading to unprecedented temporal resolution, and accurate calibration of RPI between 20 and 75 kyr B.P. We also used the 10Be and 36Cl records from the Greenland ice cores. The rate of decay of the field intensity during these two excursions is virtually identical to that observed over the last centuries and much higher than that observed for another period of low intensity (around 65 kyr BP) not associated with a polarity change. Moreover, the global morphology of the Laschamp excursion obtained by Bayesian inversion (Leonhardt et al. (2009) is that reverse magnetic field patches at the core-mantle boundary are formed near the equator and then move poleward, a scenario reminiscent of that described for the present field in the litterature. Therefore, although these results from two excursions do not provide undisputable information on future evolution of the field, they show similarities with several aspects of the present-day geomagnetic field. Assuming that the dynamo processes for an eventual future instability would be similar to those of the past two excursions, we tentatively suggest that, whilst irreversible processes that will drive the geodynamo into a polarity change may have already started, some 1000 years would be needed for the directional changes to start to be significant.

Glucose and triglyceride excursions following a standardized meal in individuals with diabetes: ELSA-Brasil study.

PubMed

Riboldi, Bárbara P; Luft, Vivian C; de Castilhos, Cristina D; de Cardoso, Letícia O; Schmidt, Maria I; Barreto, Sandhi M; de Sander, Maria F; Alvim, Sheila M; Duncan, Bruce B

2015-02-13

To assess glucose and triglyceride excursions 2 hours after the ingestion of a standardized meal and their associations with clinical characteristics and cardiovascular complications in individuals with diabetes. Blood samples of 898 subjects with diabetes were collected at fasting and 2 hours after a meal containing 455 kcal, 14 g of saturated fat and 47 g of carbohydrates. Self-reported morbidity, socio-demographic characteristics and clinical measures were obtained by interview and exams performed at the baseline visit of the ELSA-Brasil cohort study. Median (interquartile range, IQR) for fasting glucose was 150.5 (123-198) mg/dL and for fasting triglycerides 140 (103-199) mg/dL. The median excursion for glucose was 45 (15-76) mg/dL and for triglycerides 26 (11-45) mg/dL. In multiple linear regression, a greater glucose excursion was associated with higher glycated hemoglobin (10.7, 95% CI 9.1-12.3 mg/dL), duration of diabetes (4.5; 2.6-6.4 mg/dL, per 5 year increase), insulin use (44.4; 31.7-57.1 mg/dL), and age (6.1; 2.5-9.6 mg/dL, per 10 year increase); and with lower body mass index (-5.6; -8.4- -2.8 mg/dL, per 5 kg/m2 increase). In adjusted logistic regression models, a greater glucose excursion was marginally associated with the presence of cardiovascular comorbidities (coronary heart disease, myocardial infarction and angina) in those with obesity. A greater postprandial glycemic response to a small meal was positively associated with indicators of a decreased capacity for insulin secretion and negatively associated with obesity. No pattern of response was observed with a greater postprandial triglyceride excursion.

Nateglinide and Acarbose Are Comparably Effective Reducers of Postprandial Glycemic Excursions in Chinese Antihyperglycemic Agent–Naive Subjects with Type 2 Diabetes

PubMed Central

Zhou, Jian; Li, Hong; Zhang, Xiuzhen; Peng, Yongde; Mo, Yifei; Bao, Yuqian

2013-01-01

Abstract Background Recent studies have identified postprandial glycemic excursions as risk factors for diabetes complications. This study aimed to compare the effects of nateglinide and acarbose treatments on postprandial glycemic excursions in Chinese subjects with type 2 diabetes. Subjects and Methods This was a multicenter, open-label, randomized, active-controlled, parallel-group study. One hundred three antihyperglycemic agent–naive subjects with type 2 diabetes (hemoglobin A1c range, 6.5–9.0%) were prospectively recruited from four hospitals in China. The intervention was nateglinide (120 mg three times a day) or acarbose (50 mg three times a day) therapy for 2 weeks. A continuous glucose monitoring system was used to calculate the incremental area under the curve of postprandial blood glucose (AUCpp), the incremental glucose peak (IGP), mean amplitude of glycemic excursions, SD of blood glucose, the mean of daily differences, and 24-h mean blood glucose (MBG). Subjects' serum glycated albumin and the plasma insulin levels were also analyzed. Results Both agents caused significant reductions on AUCpp and IGP. Similarly, both treatment groups showed significant improvements in the intra- and interday glycemic excursions, as well as the 24-h MBG and serum glycated albumin compared with baseline (P<0.001). However, neither of the agents produced a significantly better effect (P>0.05). Moreover, the nateglinide-treated group had significantly increased insulin levels at 30 min and at 120 min after a standard meal compared with baseline, whereas the acarbose-treated group decreased. No serious adverse events occurred in either group. The rates of hypoglycemic episodes were comparable in the two groups, and no severe hypoglycemic episode occurred in either group. Conclusions Nateglinide and acarbose were comparably effective in reducing postprandial glycemic excursions in antihyperglycemic agent–naive Chinese patients with type 2 diabetes, possibly through different pathophysiological mechanisms. PMID:23631607

Alarms based on real-time sensor glucose values alert patients to hypo- and hyperglycemia: the guardian continuous monitoring system.

PubMed

Bode, Bruce; Gross, Kenneth; Rikalo, Nancy; Schwartz, Sherwyn; Wahl, Timothy; Page, Casey; Gross, Todd; Mastrototaro, John

2004-04-01

The purposes of this study were to demonstrate the accuracy and effectiveness of the Guardian Continuous Monitoring System (Medtronic MiniMed, Northridge, California) and to demonstrate that the application of real-time alarms to continuous monitoring alerts users to hypo and hyperglycemia and reduces excursions in people with diabetes. A total of 71 subjects with type 1 diabetes, mean hemoglobin A1c of 7.6 +/- 1.1%, age 44.0 +/- 11.4 years, and duration of diabetes 23.6 +/- 10.6 years were enrolled in this two-period, randomized, multicenter study. Subjects were randomized into either an Alert group or a Control group. The accuracy of the Guardian was evaluated by treating the study data as a single-sample correlational design. Effectiveness of the Guardian alerts was evaluated by comparing the Alert group with the Control group. The mean (median) absolute relative error between home blood glucose meter readings and sensor values was 21.3% (17.3%), and the Guardian, on average, read 12.8 mg/dL below the concurrent home blood glucose meter readings. The hypoglycemia alert was able to distinguished glucose values < or =70 mg/dL with 67% sensitivity, 90% specificity, and 47% false alerts. The hyperglycemia alert showed a similar ability to detect sensor values > or =250 mg/dL with 63% sensitivity, 97% specificity, and 19% false alerts. The Alert group demonstrated a median decrease in the duration of hypoglycemic excursions (-27.8 min) that was significantly greater than the median decrease in the duration of hypoglycemic excursions in the Control group (-4.5 min) (P = 0.03). A marginally significant increase in the frequency of hyperglycemic excursions (P = 0.07) between Period 1 and Period 2 was accompanied by a decrease of 9.6 min in the duration of hyperglycemic excursions in the Alert group. Glucose measurements differ between blood samples taken from the finger and interstitial fluid, especially when levels are changing rapidly; however, these results demonstrate that the Guardian is reasonably accurate while performing continuous glucose monitoring. The subjects' responses to hypoglycemia alerts resulted in a significant reduction in the duration of hypoglycemic excursions; however, overtreating hypoglycemia may have resulted in a marginally significant increase in the frequency of hyperglycemic excursions.

The influence of knee alignment on lower extremity kinetics during squats.

PubMed

Slater, Lindsay V; Hart, Joseph M

2016-12-01

The squat is an assessment of lower extremity alignment during movement, however there is little information regarding altered joint kinetics during poorly performed squats. The purpose of this study was to examine changes in joint kinetics and power from altered knee alignment during a squat. Thirty participants completed squats while displacing the knee medially, anteriorly, and with neutral alignment (control). Sagittal and frontal plane torques at the ankle, knee, and hip were altered in the descending and ascending phase of the squat in both the medial and anterior malaligned squat compared to the control squat. Ankle and trunk power increased and hip power decreased in the medial malaligned squat compared to the control squat. Ankle, knee, and trunk power increased and hip power decreased in the anterior malaligned squat compared to the control squat. Changes in joint torques and power during malaligned squats suggest that altered knee alignment increases ankle and trunk involvement to execute the movement. Increased anterior knee excursion during squatting may also lead to persistent altered loading of the ankle and knee. Sports medicine professionals using the squat for quadriceps strengthening must consider knee alignment to reduce ankle and trunk involvement during the movement. Copyright © 2016 Elsevier Ltd. All rights reserved.

Passive control of temperature excursion and uniformity in high-energy Li-ion battery packs at high current and ambient temperature

NASA Astrophysics Data System (ADS)

Kizilel, R.; Lateef, A.; Sabbah, R.; Farid, M. M.; Selman, J. R.; Al-Hallaj, S.

A strategy for portable high-power applications with a controlled thermal environment has been developed and has demonstrated the advantage of using the novel phase change material (PCM) thermal management systems over conventional active cooling systems. A passive thermal management system using PCM for Li-ion batteries is tested for extreme conditions, such as ambient temperature of 45 °C and discharge rate of 2.08 C-rate (10 A). Contrary to Li-ion packs without thermal management system, high-energy packs with PCM are discharged safely at high currents and degrading rate of capacity of the Li-ion packs lowered by half. Moreover, the compactness of the packs not only decreases the volume occupied by the packs and its associated complex cooling system, but also decreases the total weight for large power application.

NIRS-SPM: statistical parametric mapping for near infrared spectroscopy

NASA Astrophysics Data System (ADS)

Tak, Sungho; Jang, Kwang Eun; Jung, Jinwook; Jang, Jaeduck; Jeong, Yong; Ye, Jong Chul

2008-02-01

Even though there exists a powerful statistical parametric mapping (SPM) tool for fMRI, similar public domain tools are not available for near infrared spectroscopy (NIRS). In this paper, we describe a new public domain statistical toolbox called NIRS-SPM for quantitative analysis of NIRS signals. Specifically, NIRS-SPM statistically analyzes the NIRS data using GLM and makes inference as the excursion probability which comes from the random field that are interpolated from the sparse measurement. In order to obtain correct inference, NIRS-SPM offers the pre-coloring and pre-whitening method for temporal correlation estimation. For simultaneous recording NIRS signal with fMRI, the spatial mapping between fMRI image and real coordinate in 3-D digitizer is estimated using Horn's algorithm. These powerful tools allows us the super-resolution localization of the brain activation which is not possible using the conventional NIRS analysis tools.

Students' Long-Term Memories from an Ecology Field Excursion: Retelling a Narrative as an Interplay between Implicit and Explicit Memories

ERIC Educational Resources Information Center

Stolpe, Karin; Bjorklund, Lars

2013-01-01

This study aims to investigate the science content remembered by biology students 6 and 12 months after an ecology excursion. The students' memories were tested during a stimulated recall interview. The authors identified three different types of memories: "recall," "recognition" and "narratives." The "dual…

Real-Time Digital Simulation of Inertial Response with Hardware-in-the-Loop Implementation on the CART3 Wind Turbine at the National Wind Technology Center

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

Gao, Wenzhong; Wang, Xiao; Muljadi, Eduard

With increasing penetrations of wind power on electric grids, the stability and reliability of interconnected power systems may be impacted. In some countries that have developed renewable energy sources and systems, grid codes have been revised to require wind power plants (WPPs) to provide ancillary services to support the power system frequency in case of severe grid events. To do this, wind turbine generators (WTGs) should be deloaded to reserve a certain amount of active power for primary frequency response; however, deloading curtails annual energy production, and the market for this type of service needs to be further developed. Inmore » this report, we focus on the temporary frequency support provided by WTGs through inertial response. WTGs have potential to provide inertial response, but appropriate control methods should be implemented. With the implemented inertial control methods, wind turbines are capable of increasing their active power output by releasing some of their stored kinetic energy when a frequency excursion occurs. Active power can be temporarily boosted above the maximum power points, after which the rotor speed decelerates, and subsequently an active power output reduction restores the kinetic energy. In this report, we develop two types of models for wind power systems: the first is common, based on the wind power aerodynamic equation, and the power coefficient can be regressed using nonlinear functions; the second is much more complicated, wherein the wind turbine system is modeled using the Fatigue, Aerodynamics, Structures, and Turbulence Modeling (FAST) tool with several degrees of freedoms. A nine-bus test power system is built in Simulink and the Real-Time Digital Simulator, respectively, which are used to evaluate the frequency support performance of the WPPs. We implement two distinct types of inertial control methods in the modeled wind turbines: frequency-based inertial control (FBIC) and stepwise inertial control (SIC). We compare the performances of the two methods in terms of their frequency nadirs, rates of change of frequency, and recovery times. We conclude the results under various wind speeds and penetration cases, which provide insight into designing the inertial response of WTGs. Further, we discuss the impact of the parameters on the performance of the inertial control methods. We evaluate both the scaling factors for the FBIC method and the slope values for the TLIC methods. The simulation work shows the characteristics of different inertial responses compared to conventional synchronous generators. Based on the simulation results, we modify, improve, and test the inertial control methods under a more realistic wind turbine model based on FAST. We then validate the inertial responses under highly turbulent wind conditions generated by TurbSim, and we examine their influences on the turbine mechanical components. The extensive simulation proves the effectiveness of the proposed inertial control methods as well as the nine-bus test power system. We then reconsider the parameters. We rebuild the same test power system using Real time Simulator Computer Aided Design (RSCAD), and we implement the inertial control methods in the real Controls Advanced Research Turbine (CART3), which is prepared for the hardware-in-the-loop field-test simulation. After the setups for the hardware and software hybrid simulation platform are complete, the inertial response is further tested on a real wind turbine for the first time, in which CART3 release the controlled inertial response against the emulated frequency excursion, provided by the real-time simulated power system test bed in RTDS.« less

Advanced Instrumentation for Transient Reactor Testing

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

Corradini, Michael L.; Anderson, Mark; Imel, George

Transient testing involves placing fuel or material into the core of specialized materials test reactors that are capable of simulating a range of design basis accidents, including reactivity insertion accidents, that require the reactor produce short bursts of intense highpower neutron flux and gamma radiation. Testing fuel behavior in a prototypic neutron environment under high-power, accident-simulation conditions is a key step in licensing nuclear fuels for use in existing and future nuclear power plants. Transient testing of nuclear fuels is needed to develop and prove the safety basis for advanced reactors and fuels. In addition, modern fuel development and designmore » increasingly relies on modeling and simulation efforts that must be informed and validated using specially designed material performance separate effects studies. These studies will require experimental facilities that are able to support variable scale, highly instrumented tests providing data that have appropriate spatial and temporal resolution. Finally, there are efforts now underway to develop advanced light water reactor (LWR) fuels with enhanced performance and accident tolerance. These advanced reactor designs will also require new fuel types. These new fuels need to be tested in a controlled environment in order to learn how they respond to accident conditions. For these applications, transient reactor testing is needed to help design fuels with improved performance. In order to maximize the value of transient testing, there is a need for in-situ transient realtime imaging technology (e.g., the neutron detection and imaging system like the hodoscope) to see fuel motion during rapid transient excursions with a higher degree of spatial and temporal resolution and accuracy. There also exists a need for new small, compact local sensors and instrumentation that are capable of collecting data during transients (e.g., local displacements, temperatures, thermal conductivity, neutron flux, etc.).« less

Predictors of chronic ankle instability: Analysis of peroneal reaction time, dynamic balance and isokinetic strength.

PubMed

Sierra-Guzmán, Rafael; Jiménez, Fernando; Abián-Vicén, Javier

2018-05-01

Previous studies have reported the factors contributing to chronic ankle instability, which could lead to more effective treatments. However, factors such as the reflex response and ankle muscle strength have not been taken into account in previous investigations. Fifty recreational athletes with chronic ankle instability and 55 healthy controls were recruited. Peroneal reaction time in response to sudden inversion, isokinetic evertor muscle strength and dynamic balance with the Star Excursion Balance Test and the Biodex Stability System were measured. The relationship between the Cumberland Ankle Instability Tool score and performance on each test was assessed and a backward multiple linear regression analysis was conducted. Participants with chronic ankle instability showed prolonged peroneal reaction time, poor performance in the Biodex Stability System and decreased reach distance in the Star Excursion Balance Test. No significant differences were found in eversion and inversion peak torque. Moderate correlations were found between the Cumberland Ankle Instability Tool score and the peroneal reaction time and performance on the Star Excursion Balance Test. Peroneus brevis reaction time and the posteromedial and lateral directions of the Star Excursion Balance Test accounted for 36% of the variance in the Cumberland Ankle Instability Tool. Dynamic balance deficits and delayed peroneal reaction time are present in participants with chronic ankle instability. Peroneus brevis reaction time and the posteromedial and lateral directions of the Star Excursion Balance Test were the main contributing factors to the Cumberland Ankle Instability Tool score. No clear strength impairments were reported in unstable ankles. Copyright © 2018 Elsevier Ltd. All rights reserved.

Knee joint contact mechanics during downhill gait and its relationship with varus/valgus motion and muscle strength in patients with knee osteoarthritis.

PubMed

Farrokhi, Shawn; Voycheck, Carrie A; Gustafson, Jonathan A; Fitzgerald, G Kelley; Tashman, Scott

2016-01-01

The objective of this exploratory study was to evaluate tibiofemoral joint contact point excursions and velocities during downhill gait and assess the relationship between tibiofemoral joint contact mechanics with frontal-plane knee joint motion and lower extremity muscle weakness in patients with knee osteoarthritis (OA). Dynamic stereo X-ray was used to quantify tibiofemoral joint contact mechanics and frontal-plane motion during the loading response phase of downhill gait in 11 patients with knee OA and 11 control volunteers. Quantitative testing of the quadriceps and the hip abductor muscles was also performed. Patients with knee OA demonstrated larger medial/lateral joint contact point excursions (p < 0.02) and greater heel-strike joint contact point velocities (p < 0.05) for the medial and lateral compartments compared to the control group. The peak medial/lateral joint contact point velocity of the medial compartment was also greater for patients with knee OA compared to their control counterparts (p = 0.02). Additionally, patients with knee OA demonstrated significantly increased frontal-plane varus motion excursions (p < 0.01) and greater quadriceps and hip abductor muscle weakness (p = 0.03). In general, increased joint contact point excursions and velocities in patients with knee OA were linearly associated with greater frontal-plane varus motion excursions (p < 0.04) but not with quadriceps or hip abductor strength. Altered contact mechanics in patients with knee OA may be related to compromised frontal-plane joint stability but not with deficits in muscle strength.

Kinematic predictors of star excursion balance test performance in individuals with chronic ankle instability.

PubMed

Hoch, Matthew C; Gaven, Stacey L; Weinhandl, Joshua T

2016-06-01

The Star Excursion Balance Test has identified dynamic postural control deficits in individuals with chronic ankle instability. While kinematic predictors of Star Excursion Balance Test performance have been evaluated in healthy individuals, this has not been thoroughly examined in individuals with chronic ankle instability. Fifteen individuals with chronic ankle instability completed the anterior reach direction of the Star Excursion Balance Test and weight-bearing dorsiflexion assessments. Maximum reach distances on the Star Excursion Balance Test were measured in cm and normalized to leg length. Three-dimensional trunk, hip, knee, and ankle motion of the stance limb were recorded during each anterior reach trial using a motion capture system. Sagittal, frontal, and transverse plane displacement observed from trial initiation to the point of maximum reach was calculated for each joint or segment and averaged for analysis. Pearson product-moment correlations were performed to examine the relationships between kinematic variables, maximal reach, and weight-bearing dorsiflexion. A backward multiple linear regression model was developed with maximal reach as the criterion variable and kinematic variables as predictors. Frontal plane displacement of the trunk, hip, and ankle and sagittal plane knee displacement were entered into the analysis. The final model (p=0.004) included all three frontal plane variables and explained 81% of the variance in maximal reach. Maximal reach distance and several kinematic variables were significantly related to weight-bearing dorsiflexion. Individuals with chronic ankle instability who demonstrated greater lateral trunk displacement toward the stance limb, hip adduction, and ankle eversion achieved greater maximal reach. Copyright © 2016. Published by Elsevier Ltd.

Metabolic responses to prolonged consumption of glucose- and fructose-sweetened beverages are not associated with postprandial or 24-hour glucose and insulin excursions

USDA-ARS?s Scientific Manuscript database

It has been proposed that the adverse metabolic effects of chronic consumption of sugar-sweetened beverages which contain both glucose and fructose are a consequence of increased circulating glucose and insulin excursions, i.e dietary glycemic index (GI). Objective: We determined if the greater adv...

A Teaching-Learning Sequence of Colour Informed by History and Philosophy of Science

ERIC Educational Resources Information Center

Maurício, Paulo; Valente, Bianor; Chagas, Isabel

2017-01-01

In this work, we present a teaching-learning sequence on colour intended to a pre-service elementary teacher programme informed by History and Philosophy of Science. Working in a socio-constructivist framework, we made an excursion on the history of colour. Our excursion through history of colour, as well as the reported misconception on colour…

A Normative-Speaker Validation Study of Two Indices Developed to Quantify Tongue Dorsum Activity from Midsagittal Tongue Shapes

ERIC Educational Resources Information Center

Zharkova, Natalia

2013-01-01

This study reported adult scores on two measures of tongue shape, based on midsagittal tongue shape data from ultrasound imaging. One of the measures quantified the extent of tongue dorsum excursion, and the other measure represented the place of maximal excursion. Data from six adult speakers of Scottish Standard English without speech disorders…

Tuning the Field Trip: Audio-Guided Tours as a Replacement for 1-Day Excursions in Human Geography

ERIC Educational Resources Information Center

Wissmann, Torsten

2013-01-01

Educators are experiencing difficulties with 1-day field trips in human geography. Instead of teaching students how to apply theory in the field and learn to "sense" geography in everyday life, many excursions have degraded into tourist-like events where lecturers try to motivate rather passive students against a noisy urban backdrop.…

Conference Committees: Conference Committees

NASA Astrophysics Data System (ADS)

2009-09-01

International Programm Committee (IPC) Harald Ade NCSU Sadao Aoki University Tsukuba David Attwood Lawrence Berkeley National Laboratory/CXRO Christian David Paul Scherrer Institut Peter Fischer Lawrence Berkeley National Laboratory Adam Hitchcock McMaster University Chris Jacobsen SUNY, Stony Brook Denis Joyeux Lab Charles Fabry de l'Institut d'Optique Yasushi Kagoshima University of Hyogo Hiroshi Kihara Kansai Medical University Janos Kirz SUNY Stony Brook Maya Kiskinova ELETTRA Ian McNulty Argonne National Lab/APS Alan Michette Kings College London Graeme Morrison Kings College London Keith Nugent University of Melbourne Zhu Peiping BSRF Institute of High Energy Physics Francois Polack Soleil Christoph Quitmann Paul Scherrer Institut Günther Schmahl University Göttingen Gerd Schneider Bessy Hyun-Joon Shin Pohang Accelerator Lab Jean Susini ESRF Mau-Tsu Tang NSRRC Tony Warwick Lawrence Berkeley Lab/ALS Local Organizing Committee Christoph Quitmann Chair, Scientific Program Charlotte Heer Secretary Christian David Scientific Program Frithjof Nolting Scientific Program Franz Pfeiffer Scientific Program Marco Stampanoni Scientific Program Robert Rudolph Sponsoring, Financials Alfred Waser Industry Exhibition Robert Keller Public Relation Markus Knecht Computing and WWW Annick Cavedon Proceedings and Excursions and Accompanying Persons Program Margrit Eichler Excursions and Accompanying Persons Program Kathy Eikenberry Excursions and Accompanying Persons Program Marlies Locher Excursions and Accompanying Persons Program

Age of the Mono Lake excursion and associated tephra

USGS Publications Warehouse

Benson, L.; Liddicoat, J.; Smoot, J.; Sarna-Wojcicki, A.; Negrini, R.; Lund, S.

2003-01-01

The Mono Lake excursion (MLE) is an important time marker that has been found in lake and marine sediments across much of the Northern Hemisphere. Dating of this event at its type locality, the Mono Basin of California, has yielded controversial results with the most recent effort concluding that the MLE may actually be the Laschamp excursion (Earth Planet. Sci. Lett. 197 (2002) 151). We show that a volcanic tephra (Ash #15) that occurs near the midpoint of the MLE has a date (not corrected for reservoir effect) of 28,620 ?? 300 14C yr BP (??? 32,400 GISP2 yr BP) in the Pyramid Lake Basin of Nevada. Given the location of Ash #15 and the duration of the MLE in the Mono Basin, the event occurred between 31,500 and 33,300 GISP2 yr BP, an age range consistent with the position and age of the uppermost of two paleointensity minima in the NAPIS-75 stack that has been associated with the MLE (Philos. Trans. R. Soc. London Ser. A 358 (2000) 1009). The lower paleointensity minimum in the NAPIS-75 stack is considered to be the Laschamp excursion (Philos. Trans. R. Soc. London Ser. A 358 (2000) 1009).

Excursion Processes Associated with Elliptic Combinatorics

NASA Astrophysics Data System (ADS)

Baba, Hiroya; Katori, Makoto

2018-06-01

Researching elliptic analogues for equalities and formulas is a new trend in enumerative combinatorics which has followed the previous trend of studying q-analogues. Recently Schlosser proposed a lattice path model in the square lattice with a family of totally elliptic weight-functions including several complex parameters and discussed an elliptic extension of the binomial theorem. In the present paper, we introduce a family of discrete-time excursion processes on Z starting from the origin and returning to the origin in a given time duration 2 T associated with Schlosser's elliptic combinatorics. The processes are inhomogeneous both in space and time and hence expected to provide new models in non-equilibrium statistical mechanics. By numerical calculation we show that the maximum likelihood trajectories on the spatio-temporal plane of the elliptic excursion processes and of their reduced trigonometric versions are not straight lines in general but are nontrivially curved depending on parameters. We analyze asymptotic probability laws in the long-term limit T → ∞ for a simplified trigonometric version of excursion process. Emergence of nontrivial curves of trajectories in a large scale of space and time from the elementary elliptic weight-functions exhibits a new aspect of elliptic combinatorics.

Excursion Processes Associated with Elliptic Combinatorics

NASA Astrophysics Data System (ADS)

Baba, Hiroya; Katori, Makoto

2018-04-01

Researching elliptic analogues for equalities and formulas is a new trend in enumerative combinatorics which has followed the previous trend of studying q-analogues. Recently Schlosser proposed a lattice path model in the square lattice with a family of totally elliptic weight-functions including several complex parameters and discussed an elliptic extension of the binomial theorem. In the present paper, we introduce a family of discrete-time excursion processes on Z starting from the origin and returning to the origin in a given time duration 2T associated with Schlosser's elliptic combinatorics. The processes are inhomogeneous both in space and time and hence expected to provide new models in non-equilibrium statistical mechanics. By numerical calculation we show that the maximum likelihood trajectories on the spatio-temporal plane of the elliptic excursion processes and of their reduced trigonometric versions are not straight lines in general but are nontrivially curved depending on parameters. We analyze asymptotic probability laws in the long-term limit T → ∞ for a simplified trigonometric version of excursion process. Emergence of nontrivial curves of trajectories in a large scale of space and time from the elementary elliptic weight-functions exhibits a new aspect of elliptic combinatorics.

SpalLoop

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

Sabau, Adrian; Wright, Ian

Boiler tubes in steam power plants experience tube blockages due to exfoliation of oxide grown on the inner side of the tubes. In extreme cases, significant tube blockages can lead to forced power plant outages. It is thus desired to predict through modeling the amount of tube blockage in order to inform power plant operators of possible forced outages. SpalLoop solves for the stress-strain equations in an axisymmetric geometry, tracking the stress/strain evolution during boiler operation including outages for the entire boiler tube length. At each operational outage, i.e., temperature excursions down to room temperature, the amount of exfoliated areamore » for the entire tube loop is estimated the amount of tube blockage is predicted based assumed blockage geometry and site. The SpaLLoop code contains modules developed for oxide growth, stress analysis, tube loop geometry, blockage area by taking into account the following phenomena and features, (a) Plant operation schedule with periodic alternate full-load and partial-load regimes and shut-downs, i.e., temperature excursions from high-load to room temperature, (b) axisymmetric formulation for cylindrical tubes, (c) oxide growth in a temperature gradient with multiple oxide layers, (d) geometry of a boiler tube with a single tube loop or two tube loops, (e) temperature variation along the tube length based on hot gas temperature distribution outside the tube and inlet steam temperature, (f) non-uniform oxide growth along the tube length according to the local steam tube temperature, (g) exfoliated area module: at each operational outage considered, the amount of exfoliated area and exfoliated volume along the tube is estimated, (h) blockage module: at each operational outage considered, the exfoliated volume/mass for each tube loop is estimated from which the amount of tube blockage is predicted based on given blockage geometry (length, location, and geometry). The computer program is written in FORTRAN90. Its modular structure was sought for allowing the best flexibility in updating the program by implementing new constitutive equations due to availability of new material property data and/or new physical phenomena.« less

Growth of Interfacial Intermetallic Compound Layer in Diffusion-Bonded SAC-Cu Solder Joints During Different Types of Thermomechanical Excursion

NASA Astrophysics Data System (ADS)

Kanjilal, Anwesha; Kumar, Praveen

2018-01-01

The effects of mechanical strain on the growth kinetics of interfacial intermetallic compounds (IMCs) sandwiched between Cu substrate and Sn-1.0 wt.%Ag-0.5 wt.%Cu (SAC105) solder have been investigated. Isothermal aging (IA) at 70°C and 125°C, and thermal cycling (TC) as well as thermomechanical cycling (TMC) with shear strain of 12.8% per cycle between -25°C and 125°C were applied to diffusion-bonded solder joints to study the growth behavior of the interfacial IMC layer under various types of thermomechanical excursion (TME). The microstructure of the solder joint tested under each TME was observed at regular intervals. It was observed that the growth rate of the IMC layer was higher in the case of TMC compared with TC or IA. This increased growth rate of the IMC layer in the presence of mechanical strain suggests an additional driving force that enhances the growth kinetics of the IMC. Finite element analysis was performed to gain insight into the effect of TC and TMC on the stress field in the solder joint, especially near the interface between the solder and the substrate. Finally, an analytical model was developed to quantify the effect of strain on the effective diffusivity and express the growth kinetics for all three types of TME using a single expression.

Using Digital Health Technologies to Understand the Association Between Movement Behaviors and Interstitial Glucose: Exploratory Analysis

PubMed Central

Whelan, Maxine E; Sanders, James P; Sherar, Lauren B; Esliger, Dale W

2018-01-01

Background Acute reductions in postprandial glucose excursions because of movement behaviors have been demonstrated in experimental studies but less so in free-living settings. Objective The objective of this study was to explore the nature of the acute stimulus-response model between accelerometer-assessed physical activity, sedentary time, and glucose variability over 13 days in nondiabetic adults. Methods This study measured physical activity, sedentary time, and interstitial glucose continuously over 13 days in 29 participants (mean age in years: 44.9 [SD 9.1]; female: 59%, 17/29; white: 90%, 26/29; mean body mass index: 25.3 [SD 4.1]) as part of the Sensing Interstitial Glucose to Nudge Active Lifestyles (SIGNAL) research program. Daily minutes spent sedentary, in light activity, and moderate to vigorous physical activity were associated with daily mean glucose, SD of glucose, and mean amplitude of glycemic excursions (MAGE) using generalized estimating equations. Results After adjustment for covariates, sedentary time in minutes was positively associated with a higher daily mean glucose (mmol/L; beta=0.0007; 95% CI 0.00030-0.00103; P<.001), SD of glucose (mmol/L; beta=0.0006; 95% CI 0.00037-0.00081; P<.001), and MAGE (mmol/L; beta=0.002; 95% CI 0.00131-0.00273; P<.001) for those of a lower fitness. Additionally, light activity was inversely associated with mean glucose (mmol/L; beta=−0.0004; 95% CI −0.00078 to −0.00006; P=.02), SD of glucose (mmol/L; beta=−0.0006; 95% CI −0.00085 to −0.00039; P<.001), and MAGE (mmol/L; beta=−0.002; 95% CI −0.00285 to −0.00146; P<.001) for those of a lower fitness. Moderate to vigorous physical activity was only inversely associated with mean glucose (mmol/L; beta=−0.002; 95% CI −0.00250 to −0.00058; P=.002). Conclusions Evidence of an acute stimulus-response model was observed between sedentary time, physical activity, and glucose variability in low fitness individuals, with sedentary time and light activity conferring the most consistent changes in glucose variability. Further work is required to investigate the coupling of movement behaviors and glucose responses in larger samples and whether providing these rich data sources as feedback could induce lifestyle behavior change. PMID:29724703

Evaluation of pediatric ATD biofidelity as compared to child volunteers in low-speed far-side oblique and lateral impacts.

PubMed

Seacrist, Thomas; Locey, Caitlin M; Mathews, Emily A; Jones, Dakota L; Balasubramanian, Sriram; Maltese, Matthew R; Arbogast, Kristy B

2014-01-01

Motor vehicle crashes are a leading cause of injury and mortality for children. Mitigation of these injuries requires biofidelic anthropomorphic test devices (ATDs) to design and evaluate automotive safety systems. Effective countermeasures exist for frontal and near-side impacts but are limited for far-side impacts. Consequently, far-side impacts represent increased injury and mortality rates compared to frontal impacts. Thus, the objective of this study was to evaluate the biofidelity of the Hybrid III and Q-series pediatric ATDs in low-speed far-side impacts, with and without shoulder belt pretightening. Low-speed (2 g) far-side oblique (60°) and lateral (90°) sled tests were conducted using the Hybrid III and Q-series 6- and 10-year-old ATDs. ATDs were restrained by a lap and shoulder belt equipped with a precrash belt pretightener. Photoreflective targets were attached to the head, spine, shoulders, and sternum. ATDs were exposed to 8 low-speed sled tests: 2 oblique nontightened, 2 oblique pretightened, 2 lateral nontightened, 2 lateral pretightened. ATDs were compared with previously collected 9- to 11-year-old (n=10) volunteer data and newly collected 6- to 8-year-old volunteer data (n=7) tested with similar methods. Kinematic data were collected from a 3D target tracking system. Metrics of comparison included excursion, seat belt and seat pan reaction loads, belt-to-torso angle, and shoulder belt slip-out. The ATDs exhibited increased lateral excursion of the head top, C4, and T1 as well as increased downward excursion of the head top compared to the volunteers. Volunteers exhibited greater forward excursion than the ATDs in oblique nontightened impacts. These kinematics correspond to increased shoulder belt slip-out for the ATDs in oblique tests (ATDs=90%; volunteers=36%). Contrarily, similar shoulder belt slip-out was observed between ATDs and volunteers in lateral impacts (ATDs=80%; volunteers=78%). In pretightened impacts, the ATDs exhibited reduced lateral excursion and torso roll-out angle compared to the volunteers. In general, the ATDs overestimated lateral excursion in both impact directions, while underestimating forward excursion of the head and neck in oblique impacts compared to the pediatric volunteers. This was primarily due to pendulum-like lateral bending of the entire ATD torso compared to translation of the thorax relative to the abdomen prior to the lateral bending of the upper torso in the volunteers, likely due to the multisegmented spinal column in the volunteers. Additionally, the effect of belt pretightening on occupant kinematics was greater for the ATDs than the volunteers.

New successful ideas to teach Earth Science to students older than 55 by means of trekking

NASA Astrophysics Data System (ADS)

Fernández Raga, María; Cerdà, Artemi; Civera, Cristina

2013-04-01

During the last 10 years, the Geograns Program within the NAUGRAN initiative of the University of Valencia is using trekking as a way to teach in the field Earth Science. This paper review the contribution of this program and show the results and future challenges. The life expectancy is growing all over the world. This is a clear trend in the Western societies where after two generations there is a large group of inhabitants that have a new life after retirement. The universities must understand that this new group of citizens need services that will allow them to know better the society. This is why the University of Valencia developed in the end of the 90's a program to teach to students older than 55. The program that allows to those students to attend lectures at the University is called NAUGRAN. This is a program for more than one thousand students that cover the needs of a group that is having more and more population over the age of 55, and with a life expectancy that surpass the 81 years in Spain. Teaching History, Arts, Sciences or Literature can be easily due for those 55-old students. However, teaching geosciences is being very difficult, as the students must visit the field and the laboratory. Within the GEOGRANS project, and during the last six years, Physical Geography was taught to students older than 55 in independent lecture rooms and field and laboratory classes. The main strategy was to show them the concepts and the ideas of the Physical Geography in the field. The excursions allow to shown the main features of the landscape (rivers, mountains, rocks…) and the impacts of the humankind on the changes of the nature to the students. The program is now 6 years old and it is being very successful with more than 200 hundreds participants and with excursion every two weeks. This paper will show the importance of teaching to students that arrive to the university after retirement. And that trekking is a successful strategy as the students realise that they can be active and see the environmental changes suffered but the the land and the society. During the last 10 years more than 100 excursion were done by the Geograns Project. They were mainly one-day excursion, but sometimes two days excursions and one week excursions are done. The three types of excursions are showing positive acceptance of the students.

Terahertz generation via laser coupling to anharmonic carbon nanotube array

NASA Astrophysics Data System (ADS)

Sharma, Soni; Vijay, A.

2018-02-01

A scheme of terahertz radiation generation employing a matrix of anharmonic carbon nanotubes (CNTs) embedded in silica is proposed. The matrix is irradiated by two collinear laser beams that induce large excursions on CNT electrons and exert a nonlinear force at the beat frequency ω = ω1-ω2. The force derives a nonlinear current producing THz radiation. The THz field is resonantly enhanced at the plasmon resource, ω = ω p ( 1 + β ) / √{ 2 } , where ωp is the plasma frequency and β is a characteristic parameter. Collisions are a limiting factor, suppressing the plasmon resonance. For typical values of plasma parameters, we obtain power conversion efficiency of the order of 10-6.

Virtual Balancing for Studying and Training Postural Control.

PubMed

Buettner, Daniela; Dalin, Daniela; Wiesmeier, Isabella K; Maurer, Christoph

2017-01-01

Postural control during free stance has been frequently interpreted in terms of balancing an inverted pendulum. This even holds, if subjects do not balance their own, but an external body weight. We introduce here a virtual balancing apparatus, which produces torque in the ankle joint as a function of ankle angle resembling the gravity and inertial effects of free standing. As a first aim of this study, we systematically modified gravity, damping, and inertia to examine its effect on postural control beyond the physical constraints given in the real world. As a second aim, we compared virtual balancing to free stance to test its suitability for balance training in patients who are not able to balance their full body weight due to certain medical conditions. In a feasibility study, we analyzed postural control during free stance and virtual balancing in 15 healthy subjects. Postural control was characterized by spontaneous sway measures and measures of perturbed stance. During free stance, perturbations were induced by pseudorandom anterior-posterior tilts of the body support surface. In the virtual balancing task, we systematically varied the anterior-posterior position of the foot plate where the balancing forces are zero following a similar pseudorandom stimulus profile. We found that subjects' behavior during virtual balancing resembles free stance on a tilting platform. This specifically holds for the profile of body excursions as a function of stimulus frequencies. Moreover, non-linearity between stimulus and response amplitude is similar in free and virtual balancing. The overall larger stimulus induced body excursions together with an altered phase behavior between stimulus and response could be in part explained by the limited use of vestibular and visual feedback in our experimental setting. Varying gravity or damping significantly affected postural behavior. Inertia as an isolated factor had a mild effect on the response functions. We conclude that virtual balancing may be well suited to simulate conditions which could otherwise only be realized in space experiments or during parabolic flights. Further studies are needed to examine patients' potential benefit of virtual balance training.

Virtual Balancing for Studying and Training Postural Control

PubMed Central

Buettner, Daniela; Dalin, Daniela; Wiesmeier, Isabella K.; Maurer, Christoph

2017-01-01

Postural control during free stance has been frequently interpreted in terms of balancing an inverted pendulum. This even holds, if subjects do not balance their own, but an external body weight. We introduce here a virtual balancing apparatus, which produces torque in the ankle joint as a function of ankle angle resembling the gravity and inertial effects of free standing. As a first aim of this study, we systematically modified gravity, damping, and inertia to examine its effect on postural control beyond the physical constraints given in the real world. As a second aim, we compared virtual balancing to free stance to test its suitability for balance training in patients who are not able to balance their full body weight due to certain medical conditions. In a feasibility study, we analyzed postural control during free stance and virtual balancing in 15 healthy subjects. Postural control was characterized by spontaneous sway measures and measures of perturbed stance. During free stance, perturbations were induced by pseudorandom anterior-posterior tilts of the body support surface. In the virtual balancing task, we systematically varied the anterior-posterior position of the foot plate where the balancing forces are zero following a similar pseudorandom stimulus profile. We found that subjects' behavior during virtual balancing resembles free stance on a tilting platform. This specifically holds for the profile of body excursions as a function of stimulus frequencies. Moreover, non-linearity between stimulus and response amplitude is similar in free and virtual balancing. The overall larger stimulus induced body excursions together with an altered phase behavior between stimulus and response could be in part explained by the limited use of vestibular and visual feedback in our experimental setting. Varying gravity or damping significantly affected postural behavior. Inertia as an isolated factor had a mild effect on the response functions. We conclude that virtual balancing may be well suited to simulate conditions which could otherwise only be realized in space experiments or during parabolic flights. Further studies are needed to examine patients' potential benefit of virtual balance training. PMID:29018320

Enhancing the Teaching of Digital Processing of Remote Sensing Image Course through Geospatial Web Processing Services

NASA Astrophysics Data System (ADS)

di, L.; Deng, M.

2010-12-01

Remote sensing (RS) is an essential method to collect data for Earth science research. Huge amount of remote sensing data, most of them in the image form, have been acquired. Almost all geography departments in the world offer courses in digital processing of remote sensing images. Such courses place emphasis on how to digitally process large amount of multi-source images for solving real world problems. However, due to the diversity and complexity of RS images and the shortcomings of current data and processing infrastructure, obstacles for effectively teaching such courses still remain. The major obstacles include 1) difficulties in finding, accessing, integrating and using massive RS images by students and educators, and 2) inadequate processing functions and computing facilities for students to freely explore the massive data. Recent development in geospatial Web processing service systems, which make massive data, computing powers, and processing capabilities to average Internet users anywhere in the world, promises the removal of the obstacles. The GeoBrain system developed by CSISS is an example of such systems. All functions available in GRASS Open Source GIS have been implemented as Web services in GeoBrain. Petabytes of remote sensing images in NASA data centers, the USGS Landsat data archive, and NOAA CLASS are accessible transparently and processable through GeoBrain. The GeoBrain system is operated on a high performance cluster server with large disk storage and fast Internet connection. All GeoBrain capabilities can be accessed by any Internet-connected Web browser. Dozens of universities have used GeoBrain as an ideal platform to support data-intensive remote sensing education. This presentation gives a specific example of using GeoBrain geoprocessing services to enhance the teaching of GGS 588, Digital Remote Sensing taught at the Department of Geography and Geoinformation Science, George Mason University. The course uses the textbook "Introductory Digital Image Processing, A Remote Sensing Perspective" authored by John Jensen. The textbook is widely adopted in the geography departments around the world for training students on digital processing of remote sensing images. In the traditional teaching setting for the course, the instructor prepares a set of sample remote sensing images to be used for the course. Commercial desktop remote sensing software, such as ERDAS, is used for students to do the lab exercises. The students have to do the excurses in the lab and can only use the simple images. For this specific course at GMU, we developed GeoBrain-based lab excurses for the course. With GeoBrain, students now can explore petabytes of remote sensing images in the NASA, NOAA, and USGS data archives instead of dealing only with sample images. Students have a much more powerful computing facility available for their lab excurses. They can explore the data and do the excurses any time at any place they want as long as they can access the Internet through the Web Browser. The feedbacks from students are all very positive about the learning experience on the digital image processing with the help of GeoBrain web processing services. The teaching/lab materials and GeoBrain services are freely available to anyone at http://www.laits.gmu.edu.

Time-Resolved Quantitative Analysis of the Diaphragms During Tidal Breathing in a Standing Position Using Dynamic Chest Radiography with a Flat Panel Detector System ("Dynamic X-Ray Phrenicography"): Initial Experience in 172 Volunteers.

PubMed

Yamada, Yoshitake; Ueyama, Masako; Abe, Takehiko; Araki, Tetsuro; Abe, Takayuki; Nishino, Mizuki; Jinzaki, Masahiro; Hatabu, Hiroto; Kudoh, Shoji

2017-04-01

Diaphragmatic motion in a standing position during tidal breathing remains unclear. The purpose of this observational study was to evaluate diaphragmatic motion during tidal breathing in a standing position in a health screening center cohort using dynamic chest radiography in association with participants' demographic characteristics. One hundred seventy-two subjects (103 men; aged 56.3 ± 9.8 years) underwent sequential chest radiographs during tidal breathing using dynamic chest radiography with a flat panel detector system. We evaluated the excursions of and peak motion speeds of the diaphragms. Associations between the excursions and participants' demographics (gender, height, weight, body mass index [BMI], smoking history, tidal volume, vital capacity, and forced expiratory volume) were investigated. The average excursion of the left diaphragm (14.9 ± 4.6 mm, 95% CI 14.2-15.5 mm) was significantly larger than that of the right (11.0 ± 4.0 mm, 95% CI 10.4-11.6 mm) (P <0.001). The peak motion speed of the left diaphragm (inspiratory, 16.6 ± 4.2 mm/s; expiratory, 13.7 ± 4.2 mm/s) was significantly faster than that of the right (inspiratory, 12.4 ± 4.4 mm/s; expiratory, 9.4 ± 3.8 mm/s) (both P <0.001). Both simple and multiple regression models demonstrated that higher BMI and higher tidal volume were associated with increased excursions of the bilateral diaphragm (all P <0.05). The average excursions of the diaphragms are 11.0 mm (right) and 14.9 mm (left) during tidal breathing in a standing position. The diaphragmatic motion of the left is significantly larger and faster than that of the right. Higher BMI and tidal volume are associated with increased excursions of the bilateral diaphragm. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Correlation of aptian-albian carbon isotope excursions in continental strata of the cretaceous Foreland Basin, Eastern Utah, U.S.A.

USGS Publications Warehouse

Ludvigson, Greg A.; Joeckel, R.M.; Gonzalez, Luis A.; Gulbranson, E.L.; Rasbury, E.T.; Hunt, G.J.; Kirkland, J.I.; Madsen, S.

2010-01-01

Nodular carbonates ("calcretes") in continental foreland-basin strata of the Early Cretaceous Cedar Mountain Formation (CMF) in eastern Utah yield ??13C and ??O records of changes in the exogenic carbon cycle related to oceanic anoxic events (OAEs), and terrestrial paleoclimate. Chemostratigraphic profiles of both forebulge and foredeep sections show two prominent positive ??13C excursions, each with a peak value of -3% VPDB, and having background ??13C values of about -6% VPDB. These excursions correlate with the global early Aptian (Ap7) and late Aptian-early Albian (Apl2-All) carbon isotope excursions. Aptian-Albian positive ??13C excursions in the CMF also correspond to 3-4 per mil increases in carbonate ??18O. These phenomena record local aridification events. The chemostratigraphic profile on the thinner forebulge section of the CMF is calibrated, for the first time, by a radiogenic U-Pb date of 119.4 ?? 2.6 Ma on a carbonate bed, and by detrital zircon U-Pb dates on two bounding sandstone units (maximum depositional ages of 146 Ma and 112 Ma). P??trographie observations and diagenetic analyses of micritic to microsparitic carbonates from nodules indicate palustrine origins and demonstrate that they crystallized in shallow early meteoric phreatic environments. Meteoric calcite lines derived from CMF carbonates have ??18O values ranging between -8.1 to -7.5%o VPDB, supporting an estimate of zonal mean groundwater ??18O of -6% VSMOW for an Aptian-Albian paleolatitude of 34?? N. Furthermore, our two chemostratigraphic profiles exhibit a generally proportionate thinning of correlative strata from the foredeep on to the forebulge, suggesting that there were consistently lower rates of accumulation on the forebulge during the Aptian-Albian. Identification of the global Aptian-Albian ??13C excursions in purely continental strata, as demonstrated in this paper, opens a new avenue of research by identifying specific stratigraphie intervals that record the terrestrial paleoclimatic impacts of perturbations of the global carbon cycle. Copyright ?? 2010, SEPM (Society for Sedimentary Geology).

Sulfur isotope change across the Early Mississippian K-O (Kinderhookian-Osagean) δ13C excursion

NASA Astrophysics Data System (ADS)

Maharjan, Dev; Jiang, Ganqing; Peng, Yongbo; Nicholl, Michael J.

2018-07-01

Paired carbonate associate sulfate (CAS) sulfur isotopes (δ34SCAS), pyrite sulfur isotopes (δ34SPY) and CAS oxygen isotopes (δ18OCAS) across the Early Mississippian K-O δ13C excursion are documented from two sections of a west-dipping carbonate ramp in the southern Great Basin, western U.S.A. A 4-6‰ positive δ34SCAS anomaly, accompanied by negative shifts in δ34SPY and δ18OCAS, is found within the K-O δ13C excursion. In the section with a broader δ13C excursion, Δ34S (Δ34 S =δ34SCAS-δ34SPY) increases from 15‰ to 45‰ and δ13Ccarb drops from 7‰ to 4‰ at the same stratigraphic interval. If this δ34SCAS anomaly represents a global phenomenon, the large magnitude (4-6‰) and short duration (shorter than that of δ13C) suggest an unusual pyrite burial event that expanded from sediments to the ocean water column. In this scenario, the areal and volumetric expansion of sulfate reduction and pyrite burial was likely triggered by abundantly available organic matter near the peak of the K-O δ13C excursion, during which organic carbon production and burial may have reached a maximum, thus substantially expanding the oxygen minimum zone (OMZ). Numerical simulations suggest that pyrite burial rates 2.5-5 times higher than that of the modern ocean followed by sulfide oxidation are required to produce the observed δ34SCAS anomaly in a sulfate-rich ([SO4] ≥28 mM) Early Mississippian ocean. Alternatively, the sulfur and CAS oxygen isotope anomalies may record local sulfur cycling in a foreland basin where changes in weathering input and bottom-water redox conditions in response to sea-level fall and cooling resulted in isotope changes. In both scenarios (either local or global), the integrated carbon, sulfur, and CAS-oxygen isotope data suggest a much more dynamic sulfur cycle across the K-O δ13C excursion than has been previously suggested.

Effect of hamstring flexibility on hip and lumbar spine joint excursions during forward-reaching tasks in participants with and without low back pain.

PubMed

Johnson, Erica N; Thomas, James S

2010-07-01

To examine the correlation between hamstring flexibility and hip and lumbar spine joint excursions during standardized reaching and forward-bending tasks. Retrospective analysis of data obtained during 2 previous prospective studies that examined kinematics and kinetics during forward-reaching tasks in participants with and without low back pain (LBP). The 2 previous studies were conducted in the Motor Control Lab at Ohio University and the Orthopaedic Ergonomics Laboratory at The Ohio State University. Data from a total of 122 subjects from 2 previous studies: study 1: 86 subjects recovered from an episode of acute LBP (recovered) and study 2 (A.I. McCallum, unpublished data): 18 chronic LBP subjects and 18 healthy-matched controls (healthy). Not applicable. Correlation values between hamstring flexibility as measured by straight leg raise (SLR) and amount of hip and lumbar spine joint excursions used during standardized reaching and forward-bending tasks. No significant correlation was found between hamstring flexibility and hip and lumbar joint excursions during forward-bending tasks in the LBP or recovered groups. The SLR had a significant negative correlation with lumbar spine excursions during reaching tasks to a low target in the healthy group (right SLR: P=.011, left SLR: P=.004). Hamstring flexibility is not strongly related to the amount of lumbar flexion used to perform forward-reaching tasks in participants who have chronic LBP or who have recovered from LBP. More research needs to be conducted to examine the influence of hamstring flexibility on observed movement patterns to further evaluate the efficacy of flexibility training in the rehabilitation of patients with LBP. Copyright 2010 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Age and Structure of the Laschamp Geomagnetic Excursion

NASA Astrophysics Data System (ADS)

Scaillet, S.; Laj, C.; Kissel, C.; Guillou, H.; Singer, B. S.

2004-12-01

The age of the Laschamp geomagnetic excursion has been recently re-investigated using unspiked K/Ar and Ar/Ar techniques (Guillou et al., Session V01, this conference). The new age determination of 40.4 +/- 2.0 ka (2 sigma) is more precise than those previously reported in the literature and agrees precisely with that deduced from the GLOPIS-75 sedimentary paleointensity stack calibrated against the GISP2 ice core chronology. Two of the North Atlantic cores used in GLOPIS-75 (MD95-2034 and PS2644-5) yield rather detailed transitional VGP paths. In the two cases the paths show large similarities, with the VGP initially descending along mid-western Pacific, then returning to normal polarities with a large clockwise loop over Africa and Europe. Differences in the highest southern latitudes reached by the VGP can be explained assuming more different degrees of smearing of the paleomagnetic record due to differences in sedimentation rate in the two cores. In the most detailed record, MD95-2034 , two smaller loops are present preceding the main excursion. In the two cores, the excursion is characterized by a significant drop in intensity. The reversal paths observed for the Laschamp event are very close in position to those reported for the Icelandic Basin Event (IBE) from sites in the North Atlantic and the South China Sea (Laj et al., this conference) but differ in the sense of looping: while a clockwise loop is observed here, a counterclockwise loop is observed for the IBE. Despite this difference, the similarity of the transitional records tends to suggest that a similar, relatively simple, geometry has dominated the two excursions and therefore that similar dynamo mechanisms have prevailed during the reversal process.

40Ar/ 39Ar, K-Ar and 230Th- 238U dating of the Laschamp excursion: A radioisotopic tie-point for ice core and climate chronologies

NASA Astrophysics Data System (ADS)

Singer, Brad S.; Guillou, Hervé; Jicha, Brian R.; Laj, Carlo; Kissel, Catherine; Beard, Brian L.; Johnson, Clark M.

2009-08-01

A brief period of enhanced 10Be flux that straddles the interstadial warm period known as Dansgaard-Oeschger event 10 in Greenland and its counterpart in Antarctica, the Antarctic Isotope Maximum 10 is but one consequence of the weakening of Earth's magnetic field associated with the Laschamp excursion. This 10Be peak measured in the GRIP ice core is dated at 41,250 y b2k (= before year 2000 AD) in the most recent GICC05 age model obtained from the NorthGRIP core via multi-parameter counting of annual layers. Uncertainty in the age of the 10Be peak is, however, no better than ± 1630 y at the 95% confidence level, reflecting accumulated error in identifying annual layers. The age of the Laschamp excursion [Guillou, H., Singer, B.S., Laj, C., Kissel, C., Scaillet, S., Jicha, B., 2004. On the age of the Laschamp geomagnetic excursion. Earth Planet. Sci. Lett. 227, 331-343.] is revised on the basis of new 40Ar/ 39Ar, unspiked K-Ar and 238U- 230Th data from three lava flows in the Massif Central, France, together with the 40Ar/ 39Ar age of a transitionally magnetized lava flow at Auckland, New Zealand. Combined, these data yield an age of 40,700 ± 950 y b2k, where the uncertainty includes both analytical and systematic ( 40K and 230Th decay constant) errors. Taking the radioisotopic age as a calibration tie point suggests that the layer-counting chronologies for the NorthGRIP and GISP2 ice cores are more accurate and precise than previously thought at depths corresponding to the Laschamp excursion.

Agreement Between Visual Assessment and 2-Dimensional Analysis During Jump Landing Among Healthy Female Athletes.

PubMed

Rabin, Alon; Einstein, Ofira; Kozol, Zvi

2018-04-01

  Altered movement patterns, including increased frontal-plane knee movement and decreased sagittal-plane hip and knee movement, have been associated with several knee disorders. Nevertheless, the ability of clinicians to visually detect such altered movement patterns during high-speed athletic tasks is relatively unknown.   To explore the association between visual assessment and 2-dimensional (2D) analysis of frontal-plane knee movement and sagittal-plane hip and knee movement during a jump-landing task among healthy female athletes.   Cross-sectional study.   Gymnasiums of participating volleyball teams.   A total of 39 healthy female volleyball players (age = 21.0 ± 5.2 years, height = 172.0 ± 8.6 cm, mass = 64.2 ± 7.2 kg) from Divisions I and II of the Israeli Volleyball Association.   Frontal-plane knee movement and sagittal-plane hip and knee movement during jump landing were visually rated as good, moderate, or poor based on previously established criteria. Frontal-plane knee excursion and sagittal-plane hip and knee excursions were measured using free motion-analysis software and compared among athletes with different visual ratings of the corresponding movements.   Participants with different visual ratings of frontal-plane knee movement displayed differences in 2D frontal-plane knee excursion ( P < .01), whereas participants with different visual ratings of sagittal-plane hip and knee movement displayed differences in 2D sagittal-plane hip and knee excursions ( P < .01).   Visual ratings of frontal-plane knee movement and sagittal-plane hip and knee movement were associated with differences in the corresponding 2D hip and knee excursions. Visual rating of these movements may serve as an initial screening tool for detecting altered movement patterns during jump landings.

Eyelid reanimation with gold weight implant and tendon sling suspension: evaluation of excursion and velocity using the FACIAL CLIMA system.

PubMed

Hontanilla, Bernardo; Marre, Diego

2013-04-01

This study aims to analyse the efficacy of static techniques, namely gold weight implant and tendon sling, in the reanimation of the paralytic eyelid. Upper eyelid rehabilitation in terms of excursion and blinking velocity is performed using the automatic motion capture system, FACIAL CLIMA. Seventy-four patients underwent a total of 101 procedures including 58 upper eyelid gold weight implants and 43 lower eyelid tendon suspension with 27 patients undergoing both procedures. The presence of lagophtalmos, eye dryness, corneal ulcer, epiphora and lower lid ptosis/ectropion was assessed preoperatively. The Wilcoxon signed-rank test was used to compare preoperative versus postoperative measurements of upper eyelid excursion and blinking velocity determined with FACIAL CLIMA. Significance was set at p <0.05. FACIAL CLIMA revealed significant improvement of eyelid excursion and velocity of blinking (p < 0.001). Eye dryness improved in 49 patients (90.7%) and corneal ulcer resolved without any further treatment in 12 (85.7%) of those with a gold weight inserted. Implant extrusion was observed in 8.6% of the cases. Of the patients with lower lid tendon suspension, correction of ptosis/ectropion and epiphora was achieved in 93.9% and 91.9% of cases, respectively. In eight patients (18.6%), further surgery was needed to adjust tendon tension. The paralytic upper and lower eyelid can be successfully managed with gold weight implant and tendon suspension. The FACIAL CLIMA system is a reliable method to quantify upper eyelid excursion and blinking velocity and to detect the exact position of the lower eyelid. Copyright © 2012 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Mandibular kinematic changes after unilateral cross-bite with lateral shift correction.

PubMed

Venancio, F; Alarcon, J A; Lenguas, L; Kassem, M; Martin, C

2014-10-01

The aim of this randomised prospective study was to evaluate the effects of slow maxillary expansion with expansion plates and Hyrax expanders on the kinematics of the mandible after cross-bite correction. Thirty children (15 boys and 15 girls), aged 7·1-11·8, with unilateral cross-bite and functional shift were divided into two groups: expansion plate (n = 15) and Hyrax expander (n = 15). Thirty children with normal occlusion (14 boys and 16 girls, aged 7·3-11·6) served as control group. The maximum vertical opening, lateral mandibular shift (from maximum vertical opening to maximum intercuspation, from rest position to maximum intercuspation and from maximum vertical opening to rest position) and lateral excursions were recorded before and 4 months after treatment. After treatment, the expansion plate group showed a greater lateral shift from rest position to maximum intercuspation than did the control group. The expansion plate patients also presented greater left/contralateral excursion than did the control group. Comparisons of changes after treatment in the cross-bite groups showed significant decreases in the lateral shift from the maximum vertical opening to maximum intercuspation and from the maximum vertical opening to rest position, a significant increase in the homolateral excursion and a significant decrease in the contralateral excursion in the Hyrax expander group, whereas no significant differences were found in the expansion plate group. In conclusion, the Hyrax expander showed better results than did the expansion plate. The Hyrax expander with acrylic occlusal covering significantly improved the mandibular lateral shift and normalised the range of lateral excursion. © 2014 John Wiley & Sons Ltd.

An investigation of the dynamic relationship between navicular drop and first metatarsophalangeal joint dorsal excursion

PubMed Central

Griffin, Nicole L; Miller, Charlotte; Schmitt, Daniel; D'Août, Kristiaan

2013-01-01

The modern human foot is a complex biomechanical structure that must act both as a shock absorber and as a propulsive strut during the stance phase of gait. Understanding the ways in which foot segments interact can illuminate the mechanics of foot function in healthy and pathological humans. It has been proposed that increased values of medial longitudinal arch deformation can limit metatarsophalangeal joint excursion via tension in the plantar aponeurosis. However, this model has not been tested directly in a dynamic setting. In this study, we tested the hypothesis that during the stance phase, subtalar pronation (stretching of the plantar aponeurosis and subsequent lowering of the medial longitudinal arch) will negatively affect the amount of first metatarsophalangeal joint excursion occurring at push-off. Vertical descent of the navicular (a proxy for subtalar pronation) and first metatarsophalangeal joint dorsal excursion were measured during steady locomotion over a flat substrate on a novel sample consisting of asymptomatic adult males and females, many of whom are habitually unshod. Least-squares regression analyses indicated that, contrary to the hypothesis, navicular drop did not explain a significant amount of variation in first metatarsophalangeal joint dorsal excursion. These results suggest that, in an asymptomatic subject, the plantar aponeurosis and the associated foot bones can function effectively within the normal range of subtalar pronation that takes place during walking gait. From a clinical standpoint, this study highlights the need for investigating the in vivo kinematic relationship between subtalar pronation and metatarsophalangeal joint dorsiflexion in symptomatic populations, and also the need to explore other factors that may affect the kinematics of asymptomatic feet. PMID:23600634

Tonic Investigation Concept of Cervico-vestibular Muscle Afferents

PubMed Central

Dorn, Linda Josephine; Lappat, Annabelle; Neuhuber, Winfried; Scherer, Hans; Olze, Heidi; Hölzl, Matthias

2016-01-01

Introduction Interdisciplinary research has contributed greatly to an improved understanding of the vestibular system. To date, however, very little research has focused on the vestibular system's somatosensory afferents. To ensure the diagnostic quality of vestibular somatosensory afferent data, especially the extra cranial afferents, stimulation of the vestibular balance system has to be precluded. Objective Sophisticated movements require intra- and extra cranial vestibular receptors. The study's objective is to evaluate an investigation concept for cervico-vestibular afferents with respect to clinical feasibility. Methods A dedicated chair was constructed, permitting three-dimensional trunk excursions, during which the volunteer's head remains fixed. Whether or not a cervicotonic provocation nystagmus (c-PN) can be induced with static trunk excursion is to be evaluated and if this can be influenced by cervical monophasic transcutaneous electrical nerve stimulation (c-TENS) with a randomized test group. 3D-video-oculography (VOG) was used to record any change in cervico-ocular examination parameters. The occurring nystagmuses were evaluated visually due to the small caliber of nystagmus amplitudes in healthy volunteers. Results The results demonstrate: no influence of placebo-controlled c-TENS on the spontaneous nystagmus; a significant increase of the vertical nystagmus on the 3D-trunk-excursion chair in static trunk flexion with cervical provocation in all young healthy volunteers (n = 49); and a significant difference between vertical and horizontal nystagmuses during static trunk excursion after placebo-controlled c-TENS, except for the horizontal nystagmus during trunk torsion. Conclusion We hope this cervicotonic investigation concept on the 3D trunk-excursion chair will contribute to new diagnostic and therapeutic perspectives on cervical pathologies in vestibular head-to-trunk alignment. PMID:28050208

Dosimetric Considerations in Respiratory-Gated Deep Inspiration Breath-Hold for Left Breast Irradiation.

PubMed

Walston, Steve; Quick, Allison M; Kuhn, Karla; Rong, Yi

2017-02-01

To present our clinical workflow of incorporating AlignRT for left breast deep inspiration breath-hold treatments and the dosimetric considerations with the deep inspiration breath-hold protocol. Patients with stage I to III left-sided breast cancer who underwent lumpectomy or mastectomy were considered candidates for deep inspiration breath-hold technique for their external beam radiation therapy. Treatment plans were created on both free-breathing and deep inspiration breath-hold computed tomography for each patient to determine whether deep inspiration breath-hold was beneficial based on dosimetric comparison. The AlignRT system was used for patient setup and monitoring. Dosimetric measurements and their correlation with chest wall excursion and increase in left lung volume were studied for free-breathing and deep inspiration breath-hold plans. Deep inspiration breath-hold plans had significantly increased chest wall excursion when compared with free breathing. This change in geometry resulted in reduced mean and maximum heart dose but did not impact lung V 20 or mean dose. The correlation between chest wall excursion and absolute reduction in heart or lung dose was found to be nonsignificant, but correlation between left lung volume and heart dose showed a linear association. It was also identified that higher levels of chest wall excursion may paradoxically increase heart or lung dose. Reduction in heart dose can be achieved for many left-sided breast and chest wall patients using deep inspiration breath-hold. Chest wall excursion as well as left lung volume did not correlate with reduction in heart dose, and it remains to be determined what metric will provide the most optimal and reliable dosimetric advantage.

Multiple High-Frequency Carbon Isotope Excursions Across the Precambrian-Cambrian Boundary: Implications for Correlations and Environmental Change

NASA Astrophysics Data System (ADS)

Smith, E. F.; Macdonald, F. A.; Schrag, D. P.; Laakso, T.

2014-12-01

The GSSP Precambrian-Cambrian boundary in Newfoundland is defined by the first appearance datum (FAD) of Treptichnus pedum, which is considered to be roughly coincident with the FAD of small shelly fossils (SSFs) and a large negative carbon isotope excursion. An association between the FAD of T. pedum and a negative carbon isotope excursion has previously been documented in Northwest Canada (Narbonne et al., 1994) and Death Valley (Corsetti and Hagadorn, 2000), and since then has been used as an chronostratigraphic marker of the boundary, particularly in siliciclastic poor sections that do not preserve T. pedum. Here we present new high-resolution carbon isotope (δ13C ) chemostratigraphy from multiple sections in western Mongolia and the western United States that span the Ediacaran-Cambrian transition. High-resolution sampling (0.2-1 m) reveals that instead of one large negative excursion, there are multiple, high-frequency negative excursions with an overall negative trend during the latest Ediacaran. These data help to more precisely calibrate changes in the carbon cycle across the boundary as well as to highlight the potential problem of identifying the boundary with just a few negative δ13C values. We then use a simple carbon isotope box model to explore relationships between phosphorous delivery to the ocean, oxygenation, alkalinity, and turnovers in carbonate secreting organisms. Corsetti, F.A., and Hagadorn, J.W., 2000, Precambrian-Cambrian transition: Death Valley, United States: Geology, v. 28, no. 4, p. 299-302. Narbonne, G.M., Kaufman, A.J., and Knoll, A.H., 1994, Integrated chemostratigraphy and biostratigraphy of the Windermere Supergroup, northwestern Canada: Implications for Neoproterozoic correlations and the early evolution of animals: Geological Society of America Bulletin, v. 106, no. 10, p. 1281-1292.

Temperature-dependent differences in the nonlinear acoustic behavior of ultrasound contrast agents revealed by high-speed imaging and bulk acoustics.

PubMed

Mulvana, Helen; Stride, Eleanor; Tang, Mengxing; Hajnal, Jo V; Eckersley, Robert

2011-09-01

Previous work by the authors has established that increasing the temperature of the suspending liquid from 20°C to body temperature has a significant impact on the bulk acoustic properties and stability of an ultrasound contrast agent suspension (SonoVue, Bracco Suisse SA, Manno, Lugano, Switzerland). In this paper the influence of temperature on the nonlinear behavior of microbubbles is investigated, because this is one of the most important parameters in the context of diagnostic imaging. High-speed imaging showed that raising the temperature significantly influences the dynamic behavior of individual microbubbles. At body temperature, microbubbles exhibit greater radial excursion and oscillate less spherically, with a greater incidence of jetting and gas expulsion, and therefore collapse, than they do at room temperature. Bulk acoustics revealed an associated increase in the harmonic content of the scattered signals. These findings emphasize the importance of conducting laboratory studies at body temperature if the results are to be interpreted for in vivo applications. Copyright © 2011 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Thermotaxis is a Robust Mechanism for Thermoregulation in C. elegans Nematodes

PubMed Central

Ramot, Daniel; MacInnis, Bronwyn L.; Lee, Hau-Chen; Goodman, Miriam B.

2013-01-01

Many biochemical networks are robust to variations in network or stimulus parameters. Although robustness is considered an important design principle of such networks, it is not known whether this principle also applies to higher-level biological processes such as animal behavior. In thermal gradients, C. elegans uses thermotaxis to bias its movement along the direction of the gradient. Here we develop a detailed, quantitative map of C. elegans thermotaxis and use these data to derive a computational model of thermotaxis in the soil, a natural environment of C. elegans. This computational analysis indicates that thermotaxis enables animals to avoid temperatures at which they cannot reproduce, to limit excursions from their adapted temperature, and to remain relatively close to the surface of the soil, where oxygen is abundant. Furthermore, our analysis reveals that this mechanism is robust to large variations in the parameters governing both worm locomotion and temperature fluctuations in the soil. We suggest that, similar to biochemical networks, animals evolve behavioral strategies that are robust, rather than strategies that rely on fine-tuning of specific behavioral parameters. PMID:19020047

Do Behavioral Foraging Responses of Prey to Predators Function Similarly in Restored and Pristine Foodwebs?

PubMed Central

Madin, Elizabeth M. P.; Gaines, Steven D.; Madin, Joshua S.; Link, Anne-Katrin; Lubchenco, Peggy J.; Selden, Rebecca L.; Warner, Robert R.

2012-01-01

Efforts to restore top predators in human-altered systems raise the question of whether rebounds in predator populations are sufficient to restore pristine foodweb dynamics. Ocean ecosystems provide an ideal system to test this question. Removal of fishing in marine reserves often reverses declines in predator densities and size. However, whether this leads to restoration of key functional characteristics of foodwebs, especially prey foraging behavior, is unclear. The question of whether restored and pristine foodwebs function similarly is nonetheless critically important for management and restoration efforts. We explored this question in light of one important determinant of ecosystem function and structure – herbivorous prey foraging behavior. We compared these responses for two functionally distinct herbivorous prey fishes (the damselfish Plectroglyphidodon dickii and the parrotfish Chlorurus sordidus) within pairs of coral reefs in pristine and restored ecosystems in two regions of these species' biogeographic ranges, allowing us to quantify the magnitude and temporal scale of this key ecosystem variable's recovery. We demonstrate that restoration of top predator abundances also restored prey foraging excursion behaviors to a condition closely resembling those of a pristine ecosystem. Increased understanding of behavioral aspects of ecosystem change will greatly improve our ability to predict the cascading consequences of conservation tools aimed at ecological restoration, such as marine reserves. PMID:22403650

Entry Dispersion Analysis for the Stardust Comet Sample Return Capsule

NASA Technical Reports Server (NTRS)

Desai, Prasun N.; Mitcheltree, Robert A.; Cheatwood, F. McNeil

1997-01-01

Stardust will be the first mission to return samples from beyond the Earth-Moon system. The sample return capsule, which is passively controlled during the fastest Earth entry ever, will land by parachute in Utah. The present study analyzes the entry, descent, and landing of the returning sample capsule. The effects of two aerodynamic instabilities are revealed (one in the high altitude free molecular regime and the other in the transonic/subsonic flow regime). These instabilities could lead to unacceptably large excursions in the angle-of-attack near peak heating and main parachute deployment, respectively. To reduce the excursions resulting from the high altitude instability, the entry spin rate of the capsule is increased. To stabilize the excursions from the transonic/subsonic instability, a drogue chute with deployment triggered by an accelerometer and timer is added prior to main parachute deployment. A Monte Carlo dispersion analysis of the modified entry (from which the impact of off-nominal conditions during the entry is ascertained) shows that the capsule attitude excursions near peak heating and drogue chute deployment are within Stardust program limits. Additionally, the size of the resulting 3-sigma landing ellipse is 83.5 km in downrange by 29.2 km in crossrange, which is within the Utah Test and Training Range boundaries.

Recognizing the Albian-Cenomanian (OAE1d) sequence boundary using plant carbon isotopes: Dakota Formation, Western Interior Basin, USA

USGS Publications Warehouse

Grocke, D.R.; Ludvigson, Greg A.; Witzke, B.L.; Robinson, S.A.; Joeckel, R.M.; Ufnar, David F.; Ravn, R.L.

2006-01-01

Analysis of bulk sedimentary organic matter and charcoal from an Albian-Cenomanian fluvial-estuarine succession (Dakota Formation) at Rose Creek Pit (RCP), Nebraska, reveals a negative excursion of ???3???, in late Albian strata. Overlying Cenomanian strata have ??13C values of -24???, to -23???, that are similar to pre-excursion values. The absence of an intervening positive excursion (as exists in marine records of the Albian-Cenomanian boundary) likely results from a depositional hiatus. The corresponding positive ??13C event and proposed depositional hiatus are concordant with a regionally identified sequence boundary in the Dakota Formation (D2), as well as a major regressive phase throughout the globe at the Albian-Cenomanian boundary. Data from RCP confirm suggestions that some positive carbon-isotope excursions in the geologic record are coincident with regressive sea-level phases. We estimate using isotopic correlation that the D2 sequence boundary at RCP was on the order of 0.5 m.y. in duration. Therefore, interpretations of isotopic events and associated environmental phenomena, such as oceanic anoxic events, in the shallow-marine and terrestrial record may be influenced by stratigraphic incompleteness. Further investigation of terrestrial ??13C records may be useful in recognizing and constraining sea-level changes in the geologic record. ?? 2006 Geological Society of America.

The Laschamp geomagnetic excursion featured in nitrate record from EPICA-Dome C ice core

PubMed Central

Traversi, R.; Becagli, S.; Poluianov, S.; Severi, M.; Solanki, S. K.; Usoskin, I. G.; Udisti, R.

2016-01-01

Here we present the first direct comparison of cosmogenic 10Be and chemical species in the period of 38–45.5 kyr BP spanning the Laschamp geomagnetic excursion from the EPICA-Dome C ice core. A principal component analysis (PCA) allowed to group different components as a function of the main sources, transport and deposition processes affecting the atmospheric aerosol at Dome C. Moreover, a wavelet analysis highlighted the high coherence and in-phase relationship between 10Be and nitrate at this time. The evident preferential association of 10Be with nitrate rather than with other chemical species was ascribed to the presence of a distinct source, here labelled as “cosmogenic”. Both the PCA and wavelet analyses ruled out a significant role of calcium in driving the 10Be and nitrate relationship, which is particularly relevant for a plateau site such as Dome C, especially in the glacial period during which the Laschamp excursion took place. The evidence that the nitrate record from the EDC ice core is able to capture the Laschamp event hints toward the possibility of using this marker for studying galactic cosmic ray flux variations and thus also major geomagnetic field excursions at pluri-centennial-millennial time scales, thus opening up new perspectives in paleoclimatic studies. PMID:26819064

A reassessment of the role of tidal dispersion in estuaries and bays

USGS Publications Warehouse

Geyer, W. Rockwell; Signell, Richard P.

1992-01-01

The role of tidal dispersion is reassessed, based on a consideration of the relevant physical mechanisms, particularly those elucidated by numerical simulations of tide-induced dispersion. It appears that the principal influence of tidal currents on dispersion occurs at length scales of the tidal excursion and smaller; thus the effectiveness of tidal dispersion depends on the relative scale of the tidal excursion to the spacing between major bathymetric and shoreline features. In estuaries where the typical spacing of topographic features is less than the tidal excursion, tidal dispersion may contribute significantly to the overall flushing. In estuaries and embayments in which the typical spacing between major features is larger than the tidal excursion, the influence of tidal dispersion will be localized, and it will not markedly contribute to overall flushing. Tidal dispersion is most pronounced in regions of abrupt topographic changes such as headlands and inlets, where flow separation occurs. The strong strain rate in the region of flow separation tends to stretch patches of fluid into long filaments, which are subsequently rolled up and distorted by the transient eddy field. The dispersion process accomplished by the tides varies strongly as a function of position and tidal phase and thus does not lend itself to parameterization by an eddy diffusion coefficient.

A Geograns update. New experiences to teach earth sciences to students older than 55

NASA Astrophysics Data System (ADS)

Cerdà, A.; Pinazo, S.

2009-04-01

How to teach earth science to students that have access to the university after the age of 55 is a challenge due to the different background of the students. They ranged from those with only basic education (sometimes they finished school at the age of 9) to well educate students such as university professors, physicians or engineers. Students older than 55 are enrolled in what is called the university programme NauGran project at the University of Valencia. They follow diverse topics, from health science to Arts. Since 2006 the Department of Geography and the NauGran project developed the Club for Geographers and Walkers called Geograns. The objective is to teach Earth Science in the field as a strategy to improve the knowledge of the students with a direct contact with the territory. This initiative reached a successful contribution by the students, with 70 students registered. The successful strategy we have developed since then is to base our teaching on field work. Every lecture is related to some visits to the field. A pre-excursion lecture introduces the key questions of the study site (hydrology, geology, botany, geomorphology…). During the field work we review all the topics and the students are encouraged to ask and discuss any of the topics studied. Finally, a post-excursion lecture is given to review the acquired knowledge. During the last academic year 2007-2008 the excursion focussed on: (i) energy sources: problems and solutions, with visit to nuclear, wind and hydraulic power stations; (i) human disturbances and humankind as landscaper, with visits to wetlands, river gorges and Iberian settlements; and (iii) human activities and economical resources, with visits to vineyards and wineries and orange fields devoted to organic farming. This is being a positive strategy to teach Earth Science to a wide and heterogeneous group of students, as they improve their knowledge with a direct contact with the landscape, other colleagues and teachers in the field. Key Words: Teaching, Earth Science, Field work, Earth Science, Environment.

Anterior Aortic Plane Systolic Excursion: A Novel Indicator of Transplant-Free Survival in Systemic Light-Chain Amyloidosis.

PubMed

Ochs, Marco M; Riffel, Johannes; Kristen, Arnt V; Hegenbart, Ute; Schönland, Stefan; Hardt, Stefan E; Katus, Hugo A; Mereles, Derliz; Buss, Sebastian J

2016-12-01

Anterior aortic plane systolic excursion (AAPSE) was evaluated in the present pilot study as a novel echocardiographic indicator of transplant-free survival in patients with systemic light-chain amyloidosis. Eighty-nine patients with light-chain amyloidosis were included in the post-hoc analysis. A subgroup of 54 patients with biopsy-proven cardiac amyloid infiltration were compared with 41 healthy individuals to evaluate the discriminative ability of echocardiographic findings. AAPSE is defined as the systolic excursion of the anterior aortic margin. To quantify AAPSE, the M-mode cursor was placed on the aortic valve plane in parasternal long-axis view at end-diastole. Index echocardiography had been performed before chemotherapy. Median follow-up duration was 2.4 years. The primary combined end point was heart transplantation or overall death. Mean AAPSE was 14 ± 2 mm in healthy individuals (mean age=57 ± 10 years; 56% men; BMI=25 ± 4 kg/m 2 ). AAPSE < 11 mm separated patients from age-, gender-, and BMI-matched control subjects with 93% sensitivity and 97% specificity. Median transplant-free survival of patients with AAPSE < 5 mm was 0.7 versus 4.8 years (P = .0001). AAPSE was an independent indicator of transplant-free survival in multivariate Cox regression (echocardiographic model: hazard ratio=0.72 [P = .03]; biomarker model: hazard ratio=0.62 [P = .0001]). Sequential regression analysis suggested incremental power of AAPSE as a marker of transplant-free survival. An ejection fraction-based model with an overall χ 2 value of 22.8 was improved by the addition of log NT-proBNP (χ 2  = 32.6, P < .005), troponin-T (χ 2  = 39.6, P < .01), and AAPSE (χ 2  = 54.0, P < .0001). AAPSE is suggested as an indicator of transplant-free survival in patients with systemic light-chain amyloidosis. AAPSE provided significant incremental value to established staging models. Copyright © 2016 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

Statistical signal analysis of the Phanerozoic ð13C curve: implications for Earth system evolution

NASA Astrophysics Data System (ADS)

Bachan, A.; Kump, L. R.; Payne, J.; Saltzman, M.; Thomas, E.

2014-12-01

In recent years, vast amounts of carbon isotopic data have been collected allowing the construction of the Phanerozoic δ13C curve in unprecedented detail. Our dataset comprises 8143 points spanning the last 541 m.y., with a mean spacing of 66 k.y. The average δ13C of Phanerozoic carbonate is 1 ‰ ± 2 ‰, in accordance with the canonical values measured in the past. However, the record also shows numerous, highly resolved, large (± 6 ‰) excursions whose magnitude declines through time, especially going into the late Mesozoic and Cenozoic. When the magnitude - distribution of the excursions is tabulated we find that it follows a power law: plotting the min-max differences vs. number of bins in which a particular value occurs reveals that the data fall on a semilogarithmic line with a slope of -0.23 and R2 = 0.99. The result is insensitive to outliers: smoothing the data with lowess, spline, Savitzky-Golay, and Butterworth filters yields similar results. The continuity from small variation to large perturbations, both positive and negative, suggests that, despite the numerous proposed causes for individual carbon isotopic evens, there is likely an underlying mechanism which governs the magnitude of δ13C response to perturbations. We suggest that a mechanism acting to amplify carbon cycle perturbations is the key to explaining the power-law distribution, and identify the anoxia-productivity feedback as the most likely candidate. Establishment of sulfidic conditions is accompanied by increased release of phosphate to the water column, which allows for further productivity, and thus acts as a destabilizing, positive, feedback. This feedback would act to increase carbon cycle swings irrespective of their proximal trigger. The decline in frequency of anoxic-sulfidic bottom waters in the world's oceans, and potential disappearance in the Late Mesozoic-Cenozoic, may account for a reduction in the Earth system's gain and increase in its resilience.

The influence of seawater carbonate chemistry, mineralogy, and diagenesis on calcium isotope variations in Lower-Middle Triassic carbonate rocks

DOE PAGES

Lau, Kimberly V.; Maher, Kate; Brown, Shaun T.; ...

2017-11-01

The geological calcium cycle is linked to the geological carbon cycle through the weathering and burial of carbonate rocks. As a result, calcium (Ca) isotope ratios ( 44 Ca/ 40 Ca, expressed as δ 44/40 Ca) can help to constrain ancient carbon cycle dynamics if Ca cycle behavior can be reconstructed. But, the δ 44/40 Ca of carbonate rocks is influenced not only by the δ 44/40 Ca of seawater but also by diagenetic processes and fractionation associated with carbonate precipitation. In this study, we investigate the dominant controls on carbonate δ 44/40 Ca in Upper Permian to Middle Triassicmore » limestones (ca. 253 to 244 Ma) from south China and Turkey. This time interval is ideal for assessing controls on Ca isotope ratios in carbonate rocks because fluctuations in seawater δ 44/40 Ca may be expected based on several large carbon isotope (δ 13 C) excursions ranging from -2 to + 8‰. Parallel negative δ 13 C and δ 44/40 Ca excursions were previously identified across the end-Permian extinction horizon. Here, we find a second negative excursion in δ 44/40 Ca of ~ 0.2‰ within Lower Triassic strata in both south China and Turkey; however, this excursion is not synchronous between regions and thus cannot be interpreted to reflect secular change in the δ 44/40 Ca of global seawater. Additionally, δ 44/40 Ca values from Turkey are consistently 0.3‰ lower than contemporaneous samples from south China, providing further support for local or regional influences. By measuring δ 44/40 Ca and Sr concentrations ([Sr]) in two stratigraphic sections located at opposite margins of the Paleo-Tethys Ocean, we can determine whether the data represent global conditions (e.g., secular variations in the δ 44/40 Ca of seawater) versus local controls (e.g., original mineralogy or diagenetic alteration). The [Sr] and δ 44/40 Ca data from this study are best described statistically by a log-linear correlation that also exists in many previously published datasets of various geological ages. By using a model of early marine diagenetic water-rock interaction, we illustrate that this general correlation can be explained by the chemical evolution of bulk carbonate sediment samples with different initial mineralogical compositions that subsequently underwent recrystallization. Although early diagenetic resetting and carbonate mineralogy strongly influence the carbonate δ 44/40 Ca values, the relationship between [Sr] and δ 44/40 Ca holds potential for reconstructing first-order secular changes in seawater δ 44/40 Ca composition.« less

The influence of seawater carbonate chemistry, mineralogy, and diagenesis on calcium isotope variations in Lower-Middle Triassic carbonate rocks

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

Lau, Kimberly V.; Maher, Kate; Brown, Shaun T.

The geological calcium cycle is linked to the geological carbon cycle through the weathering and burial of carbonate rocks. As a result, calcium (Ca) isotope ratios ( 44 Ca/ 40 Ca, expressed as δ 44/40 Ca) can help to constrain ancient carbon cycle dynamics if Ca cycle behavior can be reconstructed. But, the δ 44/40 Ca of carbonate rocks is influenced not only by the δ 44/40 Ca of seawater but also by diagenetic processes and fractionation associated with carbonate precipitation. In this study, we investigate the dominant controls on carbonate δ 44/40 Ca in Upper Permian to Middle Triassicmore » limestones (ca. 253 to 244 Ma) from south China and Turkey. This time interval is ideal for assessing controls on Ca isotope ratios in carbonate rocks because fluctuations in seawater δ 44/40 Ca may be expected based on several large carbon isotope (δ 13 C) excursions ranging from -2 to + 8‰. Parallel negative δ 13 C and δ 44/40 Ca excursions were previously identified across the end-Permian extinction horizon. Here, we find a second negative excursion in δ 44/40 Ca of ~ 0.2‰ within Lower Triassic strata in both south China and Turkey; however, this excursion is not synchronous between regions and thus cannot be interpreted to reflect secular change in the δ 44/40 Ca of global seawater. Additionally, δ 44/40 Ca values from Turkey are consistently 0.3‰ lower than contemporaneous samples from south China, providing further support for local or regional influences. By measuring δ 44/40 Ca and Sr concentrations ([Sr]) in two stratigraphic sections located at opposite margins of the Paleo-Tethys Ocean, we can determine whether the data represent global conditions (e.g., secular variations in the δ 44/40 Ca of seawater) versus local controls (e.g., original mineralogy or diagenetic alteration). The [Sr] and δ 44/40 Ca data from this study are best described statistically by a log-linear correlation that also exists in many previously published datasets of various geological ages. By using a model of early marine diagenetic water-rock interaction, we illustrate that this general correlation can be explained by the chemical evolution of bulk carbonate sediment samples with different initial mineralogical compositions that subsequently underwent recrystallization. Although early diagenetic resetting and carbonate mineralogy strongly influence the carbonate δ 44/40 Ca values, the relationship between [Sr] and δ 44/40 Ca holds potential for reconstructing first-order secular changes in seawater δ 44/40 Ca composition.« less

Working and Learning in a Field Excursion.

PubMed

Hole, Torstein Nielsen

2018-06-01

This study aimed to discern sociocultural processes through which students learn in field excursions. To achieve this aim, short-term ethnographic techniques were employed to examine how undergraduate students work and enact knowledge (or knowing) during a specific field excursion in biology. The students participated in a working practice that employed research methods and came to engage with various biological phenomena over the course of their work. A three-level analysis of the students' experiences focused on three processes that emerged: participatory appropriation, guided participation, and apprenticeship. These processes derive from advances in practice-oriented theories of knowing. Through their work in the field, the students were able to enact science autonomously; they engaged with peers and teachers in specific ways and developed new understandings about research and epistemology founded on their experiences in the field. Further discussion about the use of "practice" and "work" as analytical concepts in science education is also included.

A Vendian-Cambrian boundary succession from the northwestern margin of the Siberian Platform: stratigraphy, palaeontology, chemostratigraphy and correlation

NASA Technical Reports Server (NTRS)

Bartley, J. K.; Pope, M.; Knoll, A. H.; Semikhatov, M. A.; Grotzinger, J. (Principal Investigator)

1998-01-01

Siberia contains several key reference sections for studies of biological and environmental evolution across the Proterozoic-Phanerozoic transition. The Platonovskaya Formation, exposed in the Turukhansk region of western Siberia, is an uppermost Proterozoic to Cambrian succession whose trace and body fossils place broad limits on the age of deposition, but do not permit detailed correlation with boundary successions elsewhere. In contrast, a striking negative carbon isotopic excursion in the lower part of the Platonovskaya Formation permits precise chemostratigraphic correlation with upper-most Yudomian successions in Siberia, and possibly worldwide. In addition to providing a tool for correlation, the isotopic excursion preserved in the Platonovskaya and contemporaneous successions documents a major biogeochemical event, likely involving the world ocean. The excursion coincides with the palaeontological breakpoint between Ediacaran- and Cambrian-style assemblages, suggesting a role for biogeochemical change in evolutionary events near the Proterozoic Cambrian boundary.

Turbulence flight director analysis and preliminary simulation

NASA Technical Reports Server (NTRS)

Johnson, D. E.; Klein, R. E.

1974-01-01

A control column and trottle flight director display system is synthesized for use during flight through severe turbulence. The column system is designed to minimize airspeed excursions without overdriving attitude. The throttle system is designed to augment the airspeed regulation and provide an indication of the trim thrust required for any desired flight path angle. Together they form an energy management system to provide harmonious display indications of current aircraft motions and required corrective action, minimize gust upset tendencies, minimize unsafe aircraft excursions, and maintain satisfactory ride qualities. A preliminary fixed-base piloted simulation verified the analysis and provided a shakedown for a more sophisticated moving-base simulation to be accomplished next. This preliminary simulation utilized a flight scenario concept combining piloting tasks, random turbulence, and discrete gusts to create a high but realistic pilot workload conducive to pilot error and potential upset. The turbulence director (energy management) system significantly reduced pilot workload and minimized unsafe aircraft excursions.

A Vendian-Cambrian boundary succession from the northwestern margin of the Siberian Platform: stratigraphy, palaeontology, chemostratigraphy and correlation.

PubMed

Bartley, J K; Pope, M; Knoll, A H; Semikhatov, M A; Petrov PYu

1998-07-01

Siberia contains several key reference sections for studies of biological and environmental evolution across the Proterozoic-Phanerozoic transition. The Platonovskaya Formation, exposed in the Turukhansk region of western Siberia, is an uppermost Proterozoic to Cambrian succession whose trace and body fossils place broad limits on the age of deposition, but do not permit detailed correlation with boundary successions elsewhere. In contrast, a striking negative carbon isotopic excursion in the lower part of the Platonovskaya Formation permits precise chemostratigraphic correlation with upper-most Yudomian successions in Siberia, and possibly worldwide. In addition to providing a tool for correlation, the isotopic excursion preserved in the Platonovskaya and contemporaneous successions documents a major biogeochemical event, likely involving the world ocean. The excursion coincides with the palaeontological breakpoint between Ediacaran- and Cambrian-style assemblages, suggesting a role for biogeochemical change in evolutionary events near the Proterozoic Cambrian boundary.

Bounded excursion stable gravastars and black holes

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

Rocha, P; Miguelote, A Y; Chan, R

2008-06-15

Dynamical models of prototype gravastars were constructed in order to study their stability. The models are the Visser-Wiltshire three-layer gravastars, in which an infinitely thin spherical shell of stiff fluid divides the whole spacetime into two regions, where the internal region is de Sitter, and the external one is Schwarzschild. It is found that in some cases the models represent the 'bounded excursion' stable gravastars, where the thin shell is oscillating between two finite radii, while in other cases they collapse until the formation of black holes occurs. In the phase space, the region for the 'bounded excursion' gravastars ismore » very small in comparison to that of black holes, but not empty. Therefore, although the possibility of the existence of gravastars cannot be excluded from such dynamical models, our results indicate that, even if gravastars do indeed exist, that does not exclude the possibility of the existence of black holes.« less

Three-dimensional, high-resolution skeletal kinematics of the avian wing and shoulder during ascending flapping flight and uphill flap-running.

PubMed

Baier, David B; Gatesy, Stephen M; Dial, Kenneth P

2013-01-01

Past studies have shown that birds use their wings not only for flight, but also when ascending steep inclines. Uphill flap-running or wing-assisted incline running (WAIR) is used by both flight-incapable fledglings and flight-capable adults to retreat to an elevated refuge. Despite the broadly varying direction of travel during WAIR, level, and descending flight, recent studies have found that the basic wing path remains relatively invariant with reference to gravity. If so, joints undergo disparate motions to maintain a consistent wing path during those specific flapping modes. The underlying skeletal motions, however, are masked by feathers and skin. To improve our understanding of the form-functional relationship of the skeletal apparatus and joint morphology with a corresponding locomotor behavior, we used XROMM (X-ray Reconstruction of Moving Morphology) to quantify 3-D skeletal kinematics in chukars (Alectoris chukar) during WAIR (ascending with legs and wings) and ascending flight (AF, ascending with wings only) along comparable trajectories. Evidence here from the wing joints demonstrates that the glenohumeral joint controls the vast majority of wing movements. More distal joints are primarily involved in modifying wing shape. All bones are in relatively similar orientations at the top of upstroke during both behaviors, but then diverge through downstroke. Total excursion of the wing is much smaller during WAIR and the tip of the manus follows a more vertical path. The WAIR stroke appears "truncated" relative to ascending flight, primarily stemming from ca. 50% reduction in humeral depression. Additionally, the elbow and wrist exhibit reduced ranges of angular excursions during WAIR. The glenohumeral joint moves in a pattern congruent with being constrained by the acrocoracohumeral ligament. Finally, we found pronounced lateral bending of the furcula during the wingbeat cycle during ascending flight only, though the phasic pattern in chukars is opposite of that observed in starlings (Sturnus vulgaris).

All-optical gain-clamped wideband serial EDFA with ring-shaped laser

NASA Astrophysics Data System (ADS)

Lu, Yung-Hsin; Chi, Sien

2004-01-01

We experimentally investigate the static and dynamic properties of all-optical gain-clamped wideband (1530-1600 nm) serial erbium-doped fiber amplifier with a single ring-shaped laser, which consists of a circulator and a fiber Bragg grating at the output end. The lasing light passing through the second stage is intentionally blocked at the output end by a C/L-band wavelength division multiplexer owning the huge insertion loss, and thus, the copropagating ring-laser light is formed by the first stage. This design can simultaneously clamp the gains of 1547 and 1584 nm probes near 14 dB and shows the same dynamic range of input power up to -4 dBm for conventional band and long-wavelength band. Furthermore, the transient responses of 1551 and 1596 nm surviving channels exhibit small power excursions (<0.54 dB) as the total saturating tone with -2 dBm is modulated on and off at 270 Hz.

A 3,000 year plant leaf wax D/H record of paleohydrology from Southern California

NASA Astrophysics Data System (ADS)

Cheetham, M. I.; Feakins, S. J.

2011-12-01

We report a high resolution record of hydrological variability based on plant leaf wax D/H measurements in a sediment core from Zaca Lake, Southern California spanning 3,000 years. Compound specific analysis of the n-alkanoic acid fraction yields a powerful suite of relative abundance and isotope data. Comparison to modern vegetation and sediments offers insights into the source of sedimentary waxes and their D/H signatures. We identify three potential sources of waxes at Zaca: 1) mid to long chains from emergent aquatic plants (C28 max), 2) mid chains from Pinus coulteri (C20-C24 only) and 3) mid to long chains from Quercus agrifolia (C28 and C30 max). We establish that long chains are dominated by Quercus and other terrestrial vegetation, whereas mid chains could have mixed sources. At Zaca, 80% shared variance between mid chain and long chain records suggests both derive from terrestrial plants influenced by a common driver, presumably the isotopic composition of precipitation or relative humidity influences on leaf water enrichment. Dendrogram analysis of molecular abundance variations allows us to flag where vegetation change cannot be ruled out. We therefore infer that regional atmospheric circulation changes drove the sustained negative isotope excursion of > 20% from about 2,700 to 2,000 years BP and superimposed higher frequency 20% variability throughout the record, including a number of large, rapid excursion (>20%, <20 years). The results of ongoing analyses will be presented at the meeting.

Age-related changes in posture response under a continuous and unexpected perturbation.

PubMed

Tsai, Yi-Ching; Hsieh, Lin-Fen; Yang, Saiwei

2014-01-22

Aging is a critical factor to influence the functional performance during daily life. Without an appropriate posture control response when experiencing an unexpected external perturbation, fall may occur. A novel six-degree-of freedom platform with motion control protocol was designed to provide a real-life simulation of unexpected disturbance in order to discriminate the age-related changes of the balance control and the recovery ability. Twenty older adults and 20 healthy young adults participated in the study. The subjects stood barefoot on the novel movable platform, data of the center of mass (COM) excursion, joint rotation angle and electromyography (EMG) were recorded and compared. The results showed that the older adults had similar patterns of joint movement and COM excursion as the young adults during the balance reactive-recovery. However, larger proximal joint rotation in elderly group induced larger COM sway envelop and therefore loss of the compensatory strategy of posture recovery. The old adults also presented a lower muscle power. In order to keep an adequate joint stability preventing from falling, the EMG activity was increased, but the asymmetric pattern might be the key reason of unstable postural response. This novel design of moveable platform and test protocol comprised the computerized dynamic posturography (CDP) demonstrate its value to assess the possible sensory, motor, and central adaptive impairments to balance control and could be the training tool for posture inability person. © 2013 Elsevier Ltd. All rights reserved.

A tail like no other. The RPC-MAG view of Rosetta's tail excursion at comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Volwerk, Martin; Goetz, Charlotte; Richter, Ingo; Delva, Magda; Ostaszewski, Katharina; Schwingenschuh, Konrad; Glassmeier, Karl-Heinz

2018-06-01

Context. The Rosetta Plasma Consortium (RPC) magnetometer (MAG) data during the tail excursion in March-April 2016 are used to investigate the magnetic structure of and activity in the tail region of the weakly outgassing comet 67P/Churyumov-Gerasimenko (67P). Aims: The goal of this study is to compare the large scale (near) tail structure with that of earlier missions to strong outgassing comets, and the small scale turbulent energy cascade (un)related to the singing comet phenomenon. Methods: The usual methods of space plasma physics are used to analyse the magnetometer data, such as minimum variance analysis, spectral analysis, and power law fitting. Also the cone angle and clock angle of the magnetic field are calculated to interpret the data. Results: It is found that comet 67P does not have a classical draped magnetic field and no bi-lobal tail structure at this late stage of the mission when the comet is already at 2.7 AU distance from the Sun. The main magnetic field direction seems to be more across the tail direction, which may implicate an asymmetric pick-up cloud. During periods of singing comet activity the propagation direction of the waves is at large angles with respect to the magnetic field and to the radial direction towards the comet. Turbulent cascade of magnetic energy from large to small scales is different in the presence of singing as without it.

A Late Cambrian Carbon Isotope Excursion Recorded in Passive Margin Dolostones of the Central Appalachian Basin, USA.

NASA Astrophysics Data System (ADS)

Mackey, J. E.; Stewart, B. W.

2016-12-01

A Late Cambrian global positive carbon isotope excursion, known as the SPICE event [1,2] is linked to possible widespread ocean anoxia and enhanced carbon burial [3,4]. We report data from the central Appalachian Conasauga Group from the upper portion of the Middle Cambrian Maryville limestone, through the Late Cambrian Nolichucky shale and Maynardville limestone members. A geochemical, macro-, and micro-scale analyses of core material from southeastern Ohio was carried out to further constrain the timing of oceanic anoxia and trace element geochemistry relative to sediment fluxes occurring at the transition of the Middle to Late Cambrian. The section represents condensed, passive margin shale deposition and carbonate ramp development on the continental shelf of Laurentia. Carbonate sediments (primarily diagenetic dolomite) record a positive δ13C (relative to V-PDB) excursion starting in the upper Nolichucky shale member, reaching its peak (+4.0) in the overlying Maynardville limestone. At this location, there is an offset between the onlap Nolichucky shale deposition and start of the C isotope excursion; this was reported as well in a carbonate section further south of this location [2], on the other side of an extensional feature (Rome Trough) that formed a deep marine basin during Cambrian time. The condensed shale package and relatively low TOC content in our samples is likely due to the combination of a shallow, upslope basin location and isostatic influence on passive margin sedimentation. However, within the Rome Trough, the Nolichucky shale is rich in organic carbon and a recent target of hydrocarbon exploration. The data suggest a possible link between deposition of this shale and the global SPICE event. The robustness of the Late Cambrian δ13C excursion in diagenetically altered sediments and association with hydrocarbon bearing units indicates its utility as a stratigraphic indicator and as a target for exploration. Ongoing geochemical work will focus on trace element and isotopic signatures preserved in the carbonate portion of sediments spanning the C isotope excursion. Refs: [1] Saltzman et al., 1998, Geol. Soc. Am. Bull. 110, 285-297; [2] Glumac and Walker, 1998, J. Sed. Res. 68, 1212-1222; [3] Hurtgen et al., 2009, Earth Planet. Sci. Lett. 281, 288-297; [4] Gill et al., 2011, Nature 469, 80-83.

Quick trips to Mars

NASA Technical Reports Server (NTRS)

Hornung, R.

1991-01-01

The design of a Mars Mission Vehicle that would have to be launched by two very heavy lift launch vehicles is described along with plans for a mission to Mars. The vehicle has three nuclear engine for rocket vehicle application (NERVA) boosters with a fourth in the center that acts as a dual mode system. The fourth generates electrical power while in route, but it also helps lift the vehicle out of earth orbit. A Mars Ascent Vehicle (MAV), a Mars transfer vehicle stage, and a Mars Excursion Vehicle (MEV) are located on the front end of this vehicle. Other aspects of this research including aerobraking, heat shielding, nuclear thermal rocket engines, a mars mission summary, closed Brayton cycle with and without regeneration, liquid hydrogen propellant storage, etc. are addressed.

Non-Gaussianity and Excursion Set Theory: Halo Bias

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

Adshead, Peter; Baxter, Eric J.; Dodelson, Scott

2012-09-01

We study the impact of primordial non-Gaussianity generated during inflation on the bias of halos using excursion set theory. We recapture the familiar result that the bias scales asmore » $$k^{-2}$$ on large scales for local type non-Gaussianity but explicitly identify the approximations that go into this conclusion and the corrections to it. We solve the more complicated problem of non-spherical halos, for which the collapse threshold is scale dependent.« less

In vivo demonstration of ultrasound power delivery to charge implanted medical devices via acute and survival porcine studies

PubMed Central

Radziemski, Leon; Makin, Inder Raj S.

2015-01-01

Animal studies are an important step in proving the utility and safety of an ultrasound based implanted battery recharging system. To this end an Ultrasound Electrical Recharging System (USER™) was developed and tested. Experiments in vitro demonstrated power deliveries at the battery of up to 600 mW through 10 – 15 mm of tissue, 50 mW of power available at tissue depths of up to 50 mm, and the feasibility of using transducers bonded to titanium as used in medical implants. Acute in vivo studies in a porcine model were used to test reliability of power delivery, temperature excursions, and cooling techniques. The culminating five-week survival study involved repeated battery charging, a total of 10.5 hours of ultrasound exposure of the intervening living tissue, with an average RF input to electrical charging efficiency of 20%. This study was potentially the first long term cumulative living-tissue exposure using transcutaneous ultrasound power transmission to an implanted receiver in situ. Histology of the exposed tissue showed changes attributable primarily due to surgical implantation of the prototype device, and no damage due to the ultrasound exposure. The in vivo results are indicative of the potential safe delivery of ultrasound energy for a defined set of source conditions for charging batteries within implants. PMID:26243566

In vivo demonstration of ultrasound power delivery to charge implanted medical devices via acute and survival porcine studies.

PubMed

Radziemski, Leon; Makin, Inder Raj S

2016-01-01

Animal studies are an important step in proving the utility and safety of an ultrasound based implanted battery recharging system. To this end an Ultrasound Electrical Recharging System (USER™) was developed and tested. Experiments in vitro demonstrated power deliveries at the battery of up to 600 mW through 10-15 mm of tissue, 50 mW of power available at tissue depths of up to 50 mm, and the feasibility of using transducers bonded to titanium as used in medical implants. Acute in vivo studies in a porcine model were used to test reliability of power delivery, temperature excursions, and cooling techniques. The culminating five-week survival study involved repeated battery charging, a total of 10.5h of ultrasound exposure of the intervening living tissue, with an average RF input to electrical charging efficiency of 20%. This study was potentially the first long term cumulative living-tissue exposure using transcutaneous ultrasound power transmission to an implanted receiver in situ. Histology of the exposed tissue showed changes attributable primarily due to surgical implantation of the prototype device, and no damage due to the ultrasound exposure. The in vivo results are indicative of the potential safe delivery of ultrasound energy for a defined set of source conditions for charging batteries within implants. Copyright © 2015 Elsevier B.V. All rights reserved.

Calcium isotope constraints on the end-Permian mass extinction

PubMed Central

Payne, Jonathan L.; Turchyn, Alexandra V.; Paytan, Adina; DePaolo, Donald J.; Lehrmann, Daniel J.; Yu, Meiyi; Wei, Jiayong

2010-01-01

The end-Permian mass extinction horizon is marked by an abrupt shift in style of carbonate sedimentation and a negative excursion in the carbon isotope (δ13C) composition of carbonate minerals. Several extinction scenarios consistent with these observations have been put forward. Secular variation in the calcium isotope (δ44/40Ca) composition of marine sediments provides a tool for distinguishing among these possibilities and thereby constraining the causes of mass extinction. Here we report δ44/40Ca across the Permian-Triassic boundary from marine limestone in south China. The δ44/40Ca exhibits a transient negative excursion of ∼0.3‰ over a few hundred thousand years or less, which we interpret to reflect a change in the global δ44/40Ca composition of seawater. CO2-driven ocean acidification best explains the coincidence of the δ44/40Ca excursion with negative excursions in the δ13C of carbonates and organic matter and the preferential extinction of heavily calcified marine animals. Calcium isotope constraints on carbon cycle calculations suggest that the average δ13C of CO2 released was heavier than -28‰ and more likely near -15‰; these values indicate a source containing substantial amounts of mantle- or carbonate-derived carbon. Collectively, the results point toward Siberian Trap volcanism as the trigger of mass extinction. PMID:20421502

Comparison of Dynamic Balance in Collegiate Field Hockey and Football Players Using Star Excursion Balance Test

PubMed Central

Bhat, Rashi; Moiz, Jamal Ali

2013-01-01

Purpose The preliminary study aimed to compare dynamic balance between collegiate athletes competing or training in football and hockey using star excursion balance test. Methods A total thirty university level players, football (n = 15) and field hockey (n = 15) were participated in the study. Dynamic balance was assessed by using star excursion balance test. The testing grid consists of 8 lines each 120 cm in length extending from a common point at 45° increments. The subjects were instructed to maintain a stable single leg stance with the test leg with shoes off and to reach for maximal distance with the other leg in each of the 8 directions. A pencil was used to point and read the distance to which each subject's foot reached. The normalized leg reach distances in each direction were summed for both limbs and the total sum of the mean of summed normalized distances of both limbs were calculated. Results There was no significant difference in all the directions of star excursion balance test scores in both the groups. Additionally, composite reach distances of both groups also found non-significant (P=0.5). However, the posterior (P=0.05) and lateral (P=0.03) normalized reach distances were significantly more in field hockey players. Conclusion Field hockey players and football players did not differ in terms of dynamic balance. PMID:24427482

Entry Trajectory Issues for the Stardust Sample Return Capsule

NASA Technical Reports Server (NTRS)

Desai, Prasun N.; Mitcheltree, Robert A.; Cheatwood, F. McNeil

1999-01-01

The Stardust mission was successfully launched on February 7, 1999. It will be the first mission to return samples from a comet. The sample return capsule, which is passively controlled during the fastest Earth entry ever, will land by parachute in Utah. The present study describes the analysis of the entry, descent, and landing of the returning sample capsule utilizing the final, launch configuration capsule mass properties. The effects of two aerodynamic instabilities are revealed (one in the high altitude free molecular regime and the other in the transonic/subsonic flow regime). These instabilities could lead to unacceptably large excursions in the angle-of-attack near peak heating and main parachute deployment, respectively. To reduce the excursions resulting from the high altitude instability, the entry spin rate of the capsule is increased. To stabilize the excursions from the transonic/subsonic instability, a drogue chute with deployment triggered by a gravity-switch and timer is added prior to main parachute deployment. A Monte Carlo dispersion analysis of the modified entry (from which the impact of off-nominal conditions during the entry is ascertained) predicts that the capsule attitude excursions near peak heating and drogue chute deployment are within Stardust mission limits. Additionally, the size of the resulting 3-sigma landing ellipse is 60.8 km in downrange by 19.9 km in crossrange, which is within the Utah Test and Training Range boundaries.

Comparison of dynamic balance in collegiate field hockey and football players using star excursion balance test.

PubMed

Bhat, Rashi; Moiz, Jamal Ali

2013-09-01

The preliminary study aimed to compare dynamic balance between collegiate athletes competing or training in football and hockey using star excursion balance test. A total thirty university level players, football (n = 15) and field hockey (n = 15) were participated in the study. Dynamic balance was assessed by using star excursion balance test. The testing grid consists of 8 lines each 120 cm in length extending from a common point at 45° increments. The subjects were instructed to maintain a stable single leg stance with the test leg with shoes off and to reach for maximal distance with the other leg in each of the 8 directions. A pencil was used to point and read the distance to which each subject's foot reached. The normalized leg reach distances in each direction were summed for both limbs and the total sum of the mean of summed normalized distances of both limbs were calculated. There was no significant difference in all the directions of star excursion balance test scores in both the groups. Additionally, composite reach distances of both groups also found non-significant (P=0.5). However, the posterior (P=0.05) and lateral (P=0.03) normalized reach distances were significantly more in field hockey players. Field hockey players and football players did not differ in terms of dynamic balance.

Doppler ultrasound surveillance in deep tunneling compressed-air work with Trimix breathing: bounce dive technique compared to saturation-excursion technique.

PubMed

Vellinga, T P van Rees; Sterk, W; de Boer, A G E M; van der Beek, A J; Verhoeven, A C; van Dijk, F J H

2008-01-01

The Western Scheldt Tunneling Project in The Netherlands provided a unique opportunity to evaluate two deep-diving techniques with Doppler ultrasound surveillance. Divers used the bounce diving techniques for repair and maintenance of the TBM. The tunnel boring machine jammed at its deepest depth. As a result the work time was not sufficient. The saturation diving technique was developed and permitted longer work time at great depth. Thirty-one divers were involved in this project. Twenty-three divers were examined using Doppler ultrasound. Data analysis addressed 52 exposures to Trimix at 4.6-4.8 bar gauge using the bounce technique and 354 exposures to Trimix at 4.0-6.9 bar gauge on saturation excursions. No decompression incidents occurred with either technique during the described phase of the project. Doppler ultrasound revealed that the bubble loads assessed in both techniques were generally low. We find out, that despite longer working hours, shorter decompression times and larger physical workloads, the saturation-excursion technique was associated with significant lower bubble grades than in the bounce technique using Doppler Ultrasound. We conclude that the saturation-excursion technique with Trimix is a good option for deep and long exposures in caisson work. The Doppler technique proved valuable, and it should be incorporated in future compressed-air work.

Masticatory motion after surgical or nonsurgical treatment for unilateral fractures of the mandibular condylar process.

PubMed

Throckmorton, Gaylord S; Ellis, Edward; Hayasaki, Haruaki

2004-02-01

We sought to compare mandibular motion during mastication in patients treated in either an open or a closed fashion for unilateral fractures of the mandibular condylar process. Eighty-one male patients with unilateral condylar process fractures were treated either with (n = 37) or without (n = 44) surgical reduction and rigid fixation of their condylar process fractures. At 6 weeks, 6 months, 1 year, and 2 years after treatment, the subjects' chewing cycles were recorded using a magnetic sensor array (Sirognathograph; Siemens Corp, Bensheim, Germany) while chewing Gummi-Bears (HARIBO, Bonn, Germany) unilaterally on the same side as the fracture and on the opposite side. The chewing cycles were analyzed using a custom computer program, and the duration, excursive ranges, and 3-dimensional cycle shape were compared between the 2 treatment groups at each time interval using multilevel linear modeling statistics. The 2 treatment groups did not differ significantly for any measure of cycle duration or any excursive range (except lateral excursions at 1 year post-treatment) at any of the time intervals. However, the 3-dimensional cycle shapes of the 2 groups did differ significantly at all time intervals. Surgical correction of unilateral condylar process fractures has relatively little effect on the more standard measures (duration and excursive ranges) of masticatory function. However, surgical correction better normalizes opening incisor pathways during mastication on the side opposite the fracture.

Accurate prediction of vaccine stability under real storage conditions and during temperature excursions.

PubMed

Clénet, Didier

2018-04-01

Due to their thermosensitivity, most vaccines must be kept refrigerated from production to use. To successfully carry out global immunization programs, ensuring the stability of vaccines is crucial. In this context, two important issues are critical, namely: (i) predicting vaccine stability and (ii) preventing product damage due to excessive temperature excursions outside of the recommended storage conditions (cold chain break). We applied a combination of advanced kinetics and statistical analyses on vaccine forced degradation data to accurately describe the loss of antigenicity for a multivalent freeze-dried inactivated virus vaccine containing three variants. The screening of large amounts of kinetic models combined with a statistical model selection approach resulted in the identification of two-step kinetic models. Predictions based on kinetic analysis and experimental stability data were in agreement, with approximately five percentage points difference from real values for long-term stability storage conditions, after excursions of temperature and during experimental shipments of freeze-dried products. Results showed that modeling a few months of forced degradation can be used to predict various time and temperature profiles endured by vaccines, i.e. long-term stability, short time excursions outside the labeled storage conditions or shipments at ambient temperature, with high accuracy. Pharmaceutical applications of the presented kinetics-based approach are discussed. Copyright © 2018 The Author. Published by Elsevier B.V. All rights reserved.

Mammalian faunal response to the Early Eocene Climatic Optimum (~53.5-48.5 mya) and a new terrestrial record of the associated carbon isotope excursion from Raven Ridge in the Uinta Basin, Colorado-Utah

NASA Astrophysics Data System (ADS)

Dutchak, A. R.

2010-12-01

Raven Ridge straddles the Colorado-Utah border on the northeastern edge of the Uinta Basin and consists of intertonguing units of the fluvial Colton and lacustrine Green River Formations. Fossil vertebrate localities along the ridge have produced a diverse mammalian fauna comprising 64 genera in 34 families. Included are the index taxa Smilodectes, Omomys, Heptodon, and Lambdotherium which suggest an age range of mid-Wasatchian (Wa5, ~53.5mya) through mid Bridgerian (Br2, ~48.5mya) for the Raven Ridge fauna. Others have shown that this time interval coincides with the onset, peak, and decline of the Early Eocene Climatic Optimum (EECO), an extended interval of globally warm temperatures following the Paleocene-Eocene Thermal Maximum (PETM) that is coincident with a large negative carbon excursion. The Raven Ridge fauna provides an excellent opportunity to investigate the effects of a lengthy interval of global warmth on mammalian diversity and ecosystem structure. To study changes in the mammalian fauna that occurred during the EECO, it was necessary to constrain the onset, peak, and decline of the EECO at Raven Ridge through chemostratigraphic correlation with established marine isotope curves. This was accomplished by analysis of approximately 300 sediment samples for Total Organic Carbon (TOC) content. TOC has been used successfully in the Bighorn Basin to identify the stratigraphic occurrence of the Carbon Isotope Excursion (CIE) associated with the PETM, which has roughly the same amplitude as the negative excursion associated with the EECO. The Raven Ridge TOC data show a large negative carbon excursion that starts during the Wa6 biochron, peaks during the Wa7 biochron, and is followed by a positive excursion near the Wa-Br boundary. This terrestrial δ13C pattern is consistent with results seen in established marine isotope curves across the EECO interval. The minimum δ13C value of the negative excursion is -29.67‰, which is comparable to the Bighorn CIE values, and the maximum δ13C value of the positive excursion is -20.51‰. The Raven Ridge mammalian fauna shows a gradual increase in generic diversity from Wa5, when the fauna was dominated by terrestrially-adapted ischyromyid rodents and the condylarth Hyopsodus, through the Wa6 and Wa7 biochrons when arboreal primates including microsyopids, omomyids, and adapids, increased in diversity and relative abundance. These results are consistent with diversity trends seen in meta-analyses of North American mammalian diversity during the EECO. The diversity increase at Raven Ridge is mirrored by a change in ranked familial abundance from a skewed distribution during Wa5 to more even distributions during Wa6-Br1 time, an interval which is shown by previous studies in Wyoming to coincide with a significant increase in floral diversity. One interpretation of these patterns is that there was a floral shift associated with the EECO in central North America, with the relatively open habitats of the mid-Wasatchian being replaced by more densely forested canopy systems, with increased niche space allowing for diversification and increased abundance of arboreal taxa, during the late Wasatchian and early Bridgerian.

In-depth analysis and characterization of a dual damascene process with respect to different CD

NASA Astrophysics Data System (ADS)

Krause, Gerd; Hofmann, Detlef; Habets, Boris; Buhl, Stefan; Gutsch, Manuela; Lopez-Gomez, Alberto; Kim, Wan-Soo; Thrun, Xaver

2018-03-01

In a 200 mm high volume environment, we studied data from a dual damascene process. Dual damascene is a combination of lithography, etch and CMP that is used to create copper lines and contacts in one single step. During these process steps, different metal CD are measured by different measurement methods. In this study, we analyze the key numbers of the different measurements after different process steps and develop simple models to predict the electrical behavior* . In addition, radial profiles have been analyzed of both inline measurement parameters and electrical parameters. A matching method was developed based on inline and electrical data. Finally, correlation analysis for radial signatures is presented that can be used to predict excursions in electrical signatures.

Heat removal capability of divertor coaxial tube assembly

NASA Astrophysics Data System (ADS)

Shibui, Masanao; Nakahira, Masataka; Tada, Eisuke; Takatsu, Hideyuki

1994-05-01

To deal with high power flowing in the divertor region, an advanced divertor concept with gas target has been proposed for use in ITER/EDA. The concept uses a divertor channel to remove the radiated power while allowing neutrals to recirculate. Candidate channel wall designs include a tube array design where many coaxial tubes are arranged in the toroidal direction to make louver. The coaxial tube consists of a Be protection tube encases many supply tubes wound helically around a return tube. V-alloy and hardened Cu-alloy have been proposed for use in the supply and return tubes. Some coolants have also been proposed for the design including pressurized He and liquid metals, because these coolants are consistent with the selection of coolants for the blanket and also meet the requirement of high temperature operation. In the coaxial tube design, the coolant area is restricted and brittle Be material is used under severe thermal cyclings. Thus, to obtain the coaxial tube with sufficient safety margin for the expected fusion power excursion, it is essential to understand its applicability limit. The paper discusses heat removal capability of the coaxial tube and recommends some design modifications.

Advanced Power Conditioning System

NASA Technical Reports Server (NTRS)

Johnson, N. L.

1971-01-01

The second portion of the advanced power conditioning system development program is reported. Five 100-watt parallel power stages with majority-vote-logic feedback-regulator were breadboarded and tested to the design goals. The input voltage range was 22.1 to 57.4 volts at loads from zero to 500 watts. The maximum input ripple current was 200 mA pk-pk (not including spikes) at 511 watts load; the output voltage was 56V dc with a maximum change of 0.89 volts for all variations of line, load, and temperature; the maximum output ripple was 320 mV pk-pk at 512 watts load (dependent on filter capacitance value); the maximum efficiency was 93.9% at 212 watts and 50V dc input; the minimum efficiency was 87.2% at 80-watt load and 50V dc input; the efficiency was above 90% from 102 watts to 372 watts; the maximum excursion for an 80-watt load change was 2.1 volts with a recovery time of 7 milliseconds; and the unit performed within regulation limits from -20 C to +85 C. During the test sequence, margin tests and failure mode tests were run with no resulting degradation in performance.

RELIABILITY OF ANKLE-FOOT MORPHOLOGY, MOBILITY, STRENGTH, AND MOTOR PERFORMANCE MEASURES.

PubMed

Fraser, John J; Koldenhoven, Rachel M; Saliba, Susan A; Hertel, Jay

2017-12-01

Assessment of foot posture, morphology, intersegmental mobility, strength and motor control of the ankle-foot complex are commonly used clinically, but measurement properties of many assessments are unclear. To determine test-retest and inter-rater reliability, standard error of measurement, and minimal detectable change of morphology, joint excursion and play, strength, and motor control of the ankle-foot complex. Reliability study. 24 healthy, recreationally-active young adults without history of ankle-foot injury were assessed by two clinicians on two occasions, three to ten days apart. Measurement properties were assessed for foot morphology (foot posture index, total and truncated length, width, arch height), joint excursion (weight-bearing dorsiflexion, rearfoot and hallux goniometry, forefoot inclinometry, 1 st metatarsal displacement) and joint play, strength (handheld dynamometry), and motor control rating during intrinsic foot muscle (IFM) exercises. Clinician order was randomized using a Latin Square. The clinicians performed independent examinations and did not confer on the findings for the duration of the study. Test-retest and inter-tester reliability and agreement was assessed using intraclass correlation coefficients (ICC 2,k ) and weighted kappa ( K w ). Test-retest reliability ICC were as follows: morphology: .80-1.00, joint excursion: .58-.97, joint play: -.67-.84, strength: .67-.92, IFM motor rating: K W -.01-.71. Inter-rater reliability ICC were as follows: morphology: .81-1.00, joint excursion: .32-.97, joint play: -1.06-1.00, strength: .53-.90, and IFM motor rating: K w .02-.56. Measures of ankle-foot posture, morphology, joint excursion, and strength demonstrated fair to excellent test-retest and inter-rater reliability. Test-retest reliability for rating of perceived difficulty and motor performance was good to excellent for short-foot, toe-spread-out, and hallux exercises and poor to fair for lesser toe extension. Joint play measures had poor to fair reliability overall. The findings of this study should be considered when choosing methods of clinical assessment and outcome measures in practice and research. 3.

Ocean sunfish rewarm at the surface after deep excursions to forage for siphonophores.

PubMed

Nakamura, Itsumi; Goto, Yusuke; Sato, Katsufumi

2015-05-01

Ocean sunfish (Mola mola) were believed to be inactive jellyfish feeders because they are often observed lying motionless at the sea surface. Recent tracking studies revealed that they are actually deep divers, but there has been no evidence of foraging in deep water. Furthermore, the surfacing behaviour of ocean sunfish was thought to be related to behavioural thermoregulation, but there was no record of sunfish body temperature. Evidence of ocean sunfish feeding in deep water was obtained using a combination of an animal-borne accelerometer and camera with a light source. Siphonophores were the most abundant prey items captured by ocean sunfish and were typically located at a depth of 50-200 m where the water temperature was <12 °C. Ocean sunfish were diurnally active, made frequently deep excursions and foraged mainly at 100-200 m depths during the day. Ocean sunfish body temperatures were measured under natural conditions. The body temperatures decreased during deep excursions and recovered during subsequent surfacing periods. Heat-budget models indicated that the whole-body heat-transfer coefficient between sunfish and the surrounding water during warming was 3-7 times greater than that during cooling. These results suggest that the main function of surfacing is the recovery of body temperature, and the fish might be able to increase heat gain from the warm surface water by physiological regulation. The thermal environment of ocean sunfish foraging depths was lower than their thermal preference (c. 16-17 °C). The behavioural and physiological thermoregulation enables the fish to increase foraging time in deep, cold water. Feeding rate during deep excursions was not related to duration or depth of the deep excursions. Cycles of deep foraging and surface warming were explained by a foraging strategy, to maximize foraging time with maintaining body temperature by vertical temperature environment. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

Coupled high-resolution marine and terrestrial records of carbon and hydrologic cycles variations during the Paleocene-Eocene Thermal Maximum (PETM)

NASA Astrophysics Data System (ADS)

Tipple, Brett J.; Pagani, Mark; Krishnan, Srinath; Dirghangi, Sitindra S.; Galeotti, Simone; Agnini, Claudia; Giusberti, Luca; Rio, Domenico

2011-11-01

The Paleocene-Eocene Thermal Maximum is characterized by a massive perturbation of the global carbon cycle reflected in a large, negative carbon isotope excursion associated with rapid global warming and changes in the hydrologic system. The magnitude of the carbon isotope excursion from terrestrial carbonates and organic carbon is generally larger relative to marine carbonates. However, high-resolution marine and terrestrial isotopic records from the same locality for direct comparison are limited. Here we present coupled carbon isotope records from terrestrial biomarkers (δ 13C n-alkane ), marine bulk carbonates (δ 13C carbonate), and bulk organic carbon (δ 13C organic) from the continuous sedimentary record of the Forada section in northern Italy in order to evaluate the magnitude and phase relationships between terrestrial and marine environments. Consistent with previous reports, we find that the carbon isotope excursion established from δ 13C n-alkane values is more negative than those established from δ 13C carbonate and δ 13C organic values. In contrast to the majority of PETM records, all Forada δ 13C records show a sharp 13C-enrichment immediately following the onset of the carbon isotope excursion. Further, the terrestrial δ 13C n-alkane record lags δ 13C carbonate/δ 13C organic trends by ~ 4-5 kyr—offsets that reflect the long residence time of soil organic carbon. Hydrogen isotope records from higher-plant leaf waxes (δD n-alkane ) and sea-surface temperatures (TEX 86) were established to assess hydrologic and ocean temperature trends. We find δD n-alkane values trend more positive, associated with higher temperatures prior to the onset of the carbon isotope excursion, and conclude that regional changes in the hydrologic cycle likely occurred before the onset of the carbon isotope anomaly.

Cerium anomaly across the mid-Tournaisian carbon isotope excursion (TICE)

NASA Astrophysics Data System (ADS)

Jiang, G.; Morales, D. C.; Maharjan, D. K.

2015-12-01

The Early Mississippian (ca. 359-345 Ma) represents one of the most important greenhouse-icehouse climate transitions in Earth history. Closely associated with this critical transition is a prominent positive carbon isotope excursion (δ13C ≥ +5‰) that has been documented from numerous stratigraphic successions across the globe. This δ13C excursion, informally referred to as the TICE (mid-Tournaisian carbon isotope excursion) event, has been interpreted as resulting from enhanced organic carbon burial, with anticipated outcomes including the lowering of atmospheric CO2 and global cooling, the growth of continental ice sheets and sea-level fall, and the increase of ocean oxygenation and ocean redox changes. The casual relationship between these events has been addressed from various perspectives but not yet clearly demonstrated. To document the potential redox change associated with the perturbation of the carbon cycle, we have analyzed rare earth elements (REE) and trace elements across the TICE in two sections across a shallow-to-deep water transect in the southern Great Basin (Utah and Nevada), USA. In both sections, the REE data show a significant positive cerium (Ce) anomaly (Ce/Ce* = Ce/(0.5La+0.5Pr)). Prior to the positive δ13C shift, most Ce/Ce* values are around 0.3 (between 0.2 and 0.4). Across the δ13C peak, Ce/Ce* values increase up to 0.87, followed by a decrease back to 0.2~0.3 after the δ13C excursion (Figure 1). The positive Ce anomaly is best interpreted as recording expansion of oxygen minimum zone and anoxia resulted from increased primary production. This is consistent with a significant increase of nitrogen isotopes (δ15N) across the δ13C peak. Integration of the carbon, nitrogen, and REE data demonstrates a responsive earth systems change linked to the perturbation of the Early Mississippian carbon cycle.

Visual evidence of the Sterno-Etrussia geomagnetic excursion (~2700 BP)?

NASA Astrophysics Data System (ADS)

Raspopov, O. M.; Dergachev, V. A.; Goos'kova, E. G.; Morner, N.-A.

2003-04-01

In the Bible's Old Testament Book of Ezekiel there is a description of the Ezekiel's vision of "a great cloud with brightness round about it" to the north of the observation site. The event described in the Bible occurred in 593 BC, i.e., approximately 2600 years ago. Ezekiel was at that time approximately 100 km south of Babylon (latitude ~ 32 N, longitude ~ 45 E). Auroral specialists interpret the Ezekiel's vision as observation of coronal auroral displays at low latitudes. However, to support this hypothesis, it is necessary to understand the physical mechanism responsible for generation of these forms of auroras at low latitudes. Analysis of palaeo- and archaeomagnetic data, including our data on magnetic properties of sediments of the Barents and White Seas and the literature data, has shown that about 2700 BP, i.e., in Ezekiel's time, development of a geomagnetic "Sterno-Etrussia" excursion took place. The duration of the excursion during which the northern geomagnetic pole wandered to the Southern Hemisphere was no more than 200-300 years. Manifestations of this excursion were found in 16 regions of the Eurasian continent and adjacent seas and also in the North and South America. By plotting the path along which the northern geomagnetic pole wandered to the southern latitudes during this excursion on the basis of palaeomagnetic data, we have found that it wandered in the longitude sector plus or minus 30 degrees, and about 2700 BP the northern geomagnetic pole was at the longitude close to the Babylon longitude, where Ezekiel had his vision. Thus, at that time Babylon was at high geomagnetic latitudes where regular coronal auroral displays occur. Records of observation of the unusual brightness of the sky in the V-VI centuries BC can also be found in Greek chronicles. This indicates that the Ezekiel's vision was not the only observation of auroras at low latitudes during the period considered here. This work was supported by INTAS, Grant 97-31008 and PFBR, Grant 00-05-64921.

Re-evaluating the isotopic divide between angiosperms and gymnosperms using n-alkane δ13C values

NASA Astrophysics Data System (ADS)

Bush, R. T.; McInerney, F. A.

2009-12-01

Angiosperm δ13C values are typically 1-3‰ more negative than those of co-occurring gymnosperms. This is known for both bulk leaf and compound-specific values from n-alkanes, which are stable, straight-chain hydrocarbons (C23-C35) found in the epicuticular leaf wax of vascular plants. For n-alkanes, there is a second distinction between the δ13C values of angiosperms and gymnosperms—δ13C values generally decrease with increasing chain-length in angiosperms, while in gymnosperms they increase. These two distinctions have been used to support the ‘plant community change hypothesis’ explaining the difference between the terrestrial and marine carbon isotope excursions during the Paleocene-Eocene Thermal Maximum (PETM.) Preserved n-alkanes from terrestrial paleosols in the Bighorn Basin, Wyoming reveal a negative carbon isotope excursion during the PETM of 4-5‰, which is 1-2‰ greater than the excursion recorded by marine carbonates. The local plant community, known from macrofossils as well as palynoflora, shifted from a deciduous, mixed angiosperm/gymnosperm flora to a suite of evergreen angiosperm species during the PETM. At the end of the PETM, the community returned to a mixed deciduous flora very similar to the original. This change in the plant community could thus magnify the terrestrial negative carbon isotope excursion to the degree necessary to explain its divergence from the marine record. However, the comparison between modern angiosperms and gymnosperms has been made mostly between broadleaf, deciduous angiosperms and evergreen, coniferous gymnosperms. New data analyzing deciduous, coniferous gymnosperms, including Metasequoia glyptostroboides and Taxodium distichum, suggests that the division previously ascribed to taxonomy may actually be based on leaf habit and physiology, specifically broadleaf, deciduous versus needle-leaf, evergreen plants. If differences in n-alkane δ13C values can be described not as angiosperms versus gymnosperms, but as deciduous versus evergreen plants, then a re-examination of the PETM terrestrial carbon isotope excursion and its causes may be necessary.

Megawatt solar power systems for lunar surface operations

NASA Technical Reports Server (NTRS)

Adams, Brian; Alhadeff, Sam; Beard, Shawn; Carlile, David; Cook, David; Douglas, Craig; Garcia, Don; Gillespie, David; Golingo, Raymond; Gonzalez, Drew

1990-01-01

Lunar surface operations require habitation, transportation, life support, scientific, and manufacturing systems, all of which require some form of power. As an alternative to nuclear power, the development of a modular one megawatt solar power system is studied, examining both photovoltaic and dynamic cycle conversion methods, along with energy storage, heat rejection, and power backup subsystems. For photovoltaic power conversion, two systems are examined. First, a substantial increase in photovoltaic conversion efficiency is realized with the use of new GaAs/GaSb tandem photovoltaic cells, offering an impressive overall array efficiency of 23.5 percent. Since these new cells are still in the experimental phase of development, a currently available GaAs cell providing 18 percent efficiency is examined as an alternate to the experimental cells. Both Brayton and Stirling cycles, powered by linear parabolic solar concentrators, are examined for dynamic cycle power conversion. The Brayton cycle is studied in depth since it is already well developed and can provide high power levels fairly efficiently in a compact, low mass system. The dynamic conversion system requires large scale waste heat rejection capability. To provide this heat rejection, a comparison is made between a heat pipe/radiative fin system using advanced composites, and a potentially less massive liquid droplet radiator system. To supply power through the lunar night, both a low temperature alkaline fuel cell system and an experimental high temperature monolithic solid-oxide fuel cell system are considered. The reactants for the fuel cells are stored cryogenically in order to avoid the high tankage mass required by conventional gaseous storage. In addition, it is proposed that the propellant tanks from a spent, prototype lunar excursion vehicle be used for this purpose, therefore resulting in a significant overall reduction in effective storage system mass.

Burst annealing of high temperature GaAs solar cells

NASA Technical Reports Server (NTRS)

Brothers, P. R.; Horne, W. E.

1991-01-01

One of the major limitations of solar cells in space power systems is their vulnerability to radiation damage. One solution to this problem is to periodically heat the cells to anneal the radiation damage. Annealing was demonstrated with silicon cells. The obstacle to annealing of GaAs cells was their susceptibility to thermal damage at the temperatures required to completely anneal the radiation damage. GaAs cells with high temperature contacts and encapsulation were developed. The cells tested are designed for concentrator use at 30 suns AMO. The circular active area is 2.5 mm in diameter for an area of 0.05 sq cm. Typical one sun AMO efficiency of these cells is over 18 percent. The cells were demonstrated to be resistant to damage after thermal excursions in excess of 600 C. This high temperature tolerance should allow these cells to survive the annealing of radiation damage. A limited set of experiments were devised to investigate the feasibility of annealing these high temperature cells. The effect of repeated cycles of electron and proton irradiation was tested. The damage mechanisms were analyzed. Limitations in annealing recovery suggested improvements in cell design for more complete recovery. These preliminary experiments also indicate the need for further study to isolate damage mechanisms. The primary objective of the experiments was to demonstrate and quantify the annealing behavior of high temperature GaAs cells. Secondary objectives were to measure the radiation degradation and to determine the effect of repeated irradiation and anneal cycles.

Estimation of Sintering Kinetics of Oxidized Magnetite Pellet Using Optical Dilatometer

NASA Astrophysics Data System (ADS)

Sandeep Kumar, T. K.; Viswanathan, Neelakantan Nurni; Ahmed, Hesham M.; Andersson, Charlotte; Björkman, Bo

2015-04-01

The quality of magnetite pellet is primarily determined by the physico-chemical changes the pellet undergoes as it makes excursion through the gaseous and thermal environment in the induration furnace. Among these physico-chemical processes, the oxidation of magnetite phase and the sintering of oxidized magnetite (hematite) and magnetite (non-oxidized) phases are vital. Rates of these processes not only depend on the thermal and gaseous environment the pellet gets exposed in the induration reactor but also interdependent on each other. Therefore, a systematic study should involve understanding these processes in isolation to the extent possible and quantify them seeking the physics. With this motivation, the present paper focusses on investigating the sintering kinetics of oxidized magnetite pellet. For the current investigation, sintering experiments were carried out on pellets containing more than 95 pct magnetite concentrate from LKAB's mine, dried and oxidized to completion at sufficiently low temperature to avoid sintering. The sintering behavior of this oxidized pellet is quantified through shrinkage captured by Optical Dilatometer. The extent of sintering characterized by sintering ratio found to follow a power law with time i.e., Kt n . The rate constant K for sintering was determined for different temperatures from isothermal experiments. The rate constant, K, varies with temperature as and the activation energy ( Q) and reaction rate constant ( K') are estimated. Further, the sintering kinetic equation was also extended to a non-isothermal environment and validated using laboratory experiments.

Free-Piston Stirling Machine for Extreme Temperatures

NASA Technical Reports Server (NTRS)

Wood, James Gary (Inventor)

2013-01-01

A free piston Stirling machine including a thermal buffer tube extending from the machine's expansion space and surrounded by its heat rejector and its regenerator, a displacer cylinder extending from the thermal buffer tube to the compression space and surrounded by the heat rejecting heat exchanger, and a displacer that reciprocates within an excursion limit that extends into the regenerator by no more than 20% of the length of the regenerator during normal operation and preferably within excursion limits that are substantially the length of the heat rejector.

Solar maximum mission panel jettison analysis remote manipulator system

NASA Technical Reports Server (NTRS)

Bauer, R. B.

1980-01-01

A study is presented of the development of the Remote Manipulator System (RMS) configurations for jettison of the solar panels on the Solar Maximum Mission/Multimission Satellite. A valid RMS maneuver between jettison configurations was developed. Arm and longeron loads and effector excursions due to the solar panel jettison were determined to see if they were within acceptable limits. These loads and end effector excursions were analyzed under two RMS modes, servos active in position hold submode, and in the brakes on mode.

Limits of Wave Runup and Corresponding Beach-Profile Change from Large-Scale Laboratory Data

DTIC Science & Technology

2010-01-01

A nearly vertical scarp developed after 40 min of wave action, with the upper limit of beach change identified at the toe of the dune scarp. and...change UL was found to approximately equal the vertical excursion of total wave runup, Rtw. An exception was runs where beach or dune scarps were...approximately equal the vertical excursion of total wave runup, Rtw. An exception was runs where beach or dune scarps were produced, which substantially limit the

Excursion set mass functions for hierarchical Gaussian fluctuations

NASA Technical Reports Server (NTRS)

Bond, J. R.; Kaiser, N.; Cole, S.; Efstathiou, G.

1991-01-01

It is pointed out that most schemes for determining the mass function of virialized objects from the statistics of the initial density perturbation field suffer from the cloud-in-cloud problem of miscounting the number of low-mass clumps, many of which would have been subsumed into larger objects. The paper proposes a solution based on the theory of the excursion sets of F(r, R sub f), the four-dimensional initial density perturbation field smoothed with a continuous hierarchy of filters of radii R sub f.

Osmium isotope perturbations during the Pliensbachian-Toarcian (Early Jurassic): Relationships between volcanism, weathering, and climate change

NASA Astrophysics Data System (ADS)

Percival, Lawrence; Cohen, Anthony; Davies, Marc; Dickson, Alexander; Jenkyns, Hugh; Hesselbo, Stephen; Mather, Tamsin; Xu, Weimu; Storm, Marisa

2016-04-01

The Mesozoic Era marked a time of greenhouse conditions on Earth, punctuated by a number of abrupt perturbations to the carbon cycle, such as Ocean Anoxic Events (OAEs). OAEs are typically marked in the stratigraphic record by the appearance of organic-rich shales, and excursions in carbon-isotope ratios registered in carbonates and organic matter. A range of geochemical evidence indicates changes to global temperatures, typically featuring abrupt warming possibly caused by CO2 emissions resulting from Large Igneous Province (LIP) volcanism. A warmer atmosphere is thought to have led to changes in the global hydrological cycle, which would likely have enhanced global weathering rates. The Toarcian OAE (T-OAE) is inferred, from osmium isotope ratios in organic-rich mudrocks from Yorkshire and western North America, to have been a time of such increased weathering rates. However, it is likely that the sediments at these locations were deposited in relatively hydrographically restricted environments, potentially more susceptible to the influence of local input; consequently, they may not offer the best representation of the global seawater Os-isotope composition at that time. In this study, we have measured the osmium isotope composition of siciliclastic mudrocks in a core from the Mochras borehole (Llanbedr Farm, Cardigan Bay Basin, Wales), which constitutes a sedimentary record for a fully open-marine seaway that connected Tethys to the Boreal ocean during the Toarcian. We analysed samples from strata including both the T-OAE and preceding Pliensbachian-Toarcian boundary (Pl-To), both of which record multiple geochemical excursions and records of elevated extinction amongst benthic fauna. We find that the latest Pliensbachian records seawater 187Os/188Os of ~0.35-0.4, rising to ~0.5 at the Pl-To boundary, before a further rise to ~0.7 during the T-OAE. We conclude that such increases in radiogenic Os flux to the ocean system resulted from enhanced continental weathering, and note that both excursions coincide with negative excursions in δ13C (indicating a massive release of isotopically light carbon to the atmosphere) and positive excursions in Hg/TOC (indicating enhanced volcanic activity associated with the Karoo-Ferrar LIP). These concurrent changes suggest that carbon-emissions related to the Karoo-Ferrar may have aided climate warming, leading to the enhanced weathering and marine anoxia recorded in Toarcian strata. Additionally, we record a potential lag in the recovery of 187Os/188Os compared to δ13C; such a lag would support previous hypotheses that enhanced weathering contributed towards draw-down of excess atmospheric carbon, alleviating the Toarcian warming. Finally, our recording of a second (stratigraphically lower) excursion in Os isotopes, coincident with previously recorded excursions, indicates that major climate change during the Toarcian in fact began, albeit to a lesser degree, at the Pl-To boundary, rather than being restricted solely to the T-OAE.

How Doth the Little Crocodilian: Analyzing the Influence of Environmental Viscosity on Feeding Performance of Juvenile Alligator mississippiensis

PubMed Central

Kerfoot, James R.; Easter, Emily; Elsey, Ruth M.

2016-01-01

Wetland habitats are used as nursery sites for hatchling and juvenile alligators (Alligator mississippiensis), where they utilize prey from aquatic and terrestrial settings. However, little is known about how viscosity of the medium influences feeding performance. We hypothesized that timing and linear excursion feeding kinematic variables would be different for individuals feeding on prey above the water compared with the same individuals feeding underwater. Individuals were fed immobile fish prey and feeding events were recorded using a high speed video camera. Feeding performance was summarized by analyzing three feeding kinematic variables (maximum gape, maximum gape velocity, duration of feeding bout) and success of strike. Results of a series of paired t-tests indicated no significant difference in kinematic variables between feeding events above water compared with underwater. Similarity in feeding performance could indicate that prey-capture is not altered by environmental viscosity or that feeding behavior can mitigate its influence. Behavioral differences were observed during feeding events with alligators approaching underwater prey having their mouths partially opened versus fully closed when feeding above water. This behavior could be an indication of a strategy used to overcome water viscosity. PMID:27706023

Olfactory-mediated stream-finding behavior of migratory adult sea lamprey (Petromyzon marinus)

USGS Publications Warehouse

Vrieze, L.A.; Bergstedt, R.A.; Sorensen, P.W.

2011-01-01

Stream-finding behavior of adult sea lamprey (Petromyzon marinus), an anadromous fish that relies on pheromones to locate spawning streams, was documented in the vicinity of an important spawning river in the Great Lakes. Untreated and anosmic migrating sea lampreys were implanted with acoustic transmitters and then released outside the Ocqueoc River. Lampreys swam only at night and then actively. When outside of the river plume, lampreys pursued relatively straight bearings parallel to the shoreline while making frequent vertical excursions. In contrast, when within the plume, lampreys made large turns and exhibited a weak bias towards the river mouth, which one-third of them entered. The behavior of anosmic lampreys resembled that of untreated lampreys outside of the plume, except they pursued a more northerly compass bearing. To locate streams, sea lampreys appear to employ a three-phase odor-mediated strategy that involves an initial search along shorelines while casting vertically, followed by river-water-induced turning that brings them close to the river's mouth, which they then enter using rheotaxis. This novel strategy differs from that of salmonids and appears to offer this poor swimmer adaptive flexibility and suggests ways that pheromonal odors might be used to manage this invasive species.

Lotka-Volterra system in a random environment.

PubMed

Dimentberg, Mikhail F

2002-03-01

Classical Lotka-Volterra (LV) model for oscillatory behavior of population sizes of two interacting species (predator-prey or parasite-host pairs) is conservative. This may imply unrealistically high sensitivity of the system's behavior to environmental variations. Thus, a generalized LV model is considered with the equation for preys' reproduction containing the following additional terms: quadratic "damping" term that accounts for interspecies competition, and term with white-noise random variations of the preys' reproduction factor that simulates the environmental variations. An exact solution is obtained for the corresponding Fokker-Planck-Kolmogorov equation for stationary probability densities (PDF's) of the population sizes. It shows that both population sizes are independent gamma-distributed stationary random processes. Increasing level of the environmental variations does not lead to extinction of the populations. However it may lead to an intermittent behavior, whereby one or both population sizes experience very rare and violent short pulses or outbreaks while remaining on a very low level most of the time. This intermittency is described analytically by direct use of the solutions for the PDF's as well as by applying theory of excursions of random functions and by predicting PDF of peaks in the predators' population size.

Lotka-Volterra system in a random environment

NASA Astrophysics Data System (ADS)

Dimentberg, Mikhail F.

2002-03-01

Classical Lotka-Volterra (LV) model for oscillatory behavior of population sizes of two interacting species (predator-prey or parasite-host pairs) is conservative. This may imply unrealistically high sensitivity of the system's behavior to environmental variations. Thus, a generalized LV model is considered with the equation for preys' reproduction containing the following additional terms: quadratic ``damping'' term that accounts for interspecies competition, and term with white-noise random variations of the preys' reproduction factor that simulates the environmental variations. An exact solution is obtained for the corresponding Fokker-Planck-Kolmogorov equation for stationary probability densities (PDF's) of the population sizes. It shows that both population sizes are independent γ-distributed stationary random processes. Increasing level of the environmental variations does not lead to extinction of the populations. However it may lead to an intermittent behavior, whereby one or both population sizes experience very rare and violent short pulses or outbreaks while remaining on a very low level most of the time. This intermittency is described analytically by direct use of the solutions for the PDF's as well as by applying theory of excursions of random functions and by predicting PDF of peaks in the predators' population size.

Osmium isotope evidence for a large Late Triassic impact event

PubMed Central

Sato, Honami; Onoue, Tetsuji; Nozaki, Tatsuo; Suzuki, Katsuhiko

2013-01-01

Anomalously high platinum group element concentrations have previously been reported for Upper Triassic deep-sea sediments, which are interpreted to be derived from an extraterrestrial impact event. Here we report the osmium (Os) isotope fingerprint of an extraterrestrial impact from Upper Triassic chert successions in Japan. Os isotope data exhibit a marked negative excursion from an initial Os isotope ratio (187Os/188Osi) of ∼0.477 to unradiogenic values of ∼0.126 in a platinum group element-enriched claystone layer, indicating the input of meteorite-derived Os into the sediments. The timing of the Os isotope excursion coincides with both elevated Os concentrations and low Re/Os ratios. The magnitude of this negative Os isotope excursion is comparable to those found at Cretaceous–Paleogene boundary sites. These geochemical lines of evidence demonstrate that a large impactor (3.3–7.8 km in diameter) produced a global decrease in seawater 187Os/188Os ratios in the Late Triassic. PMID:24036603

Magnetic flux ropes in the Venus ionosphere - Observations and models

NASA Technical Reports Server (NTRS)

Elphic, R. C.; Russell, C. T.

1983-01-01

Pioneer Venus Orbiter data are used as evidence of naturally occurring magnetic field filamentary structures which can be described by a flux rope model. The solar wind is interpreted as piling up a magnetic field on the Venus ionosphere, with the incident ram pressure being expressed as magnetic field pressure. Currents flowing at the ionopause shield out the field, allowing magnetic excursions to be observed with magnitudes of tens of nT over an interval of a few seconds. A quantitative assessment is made of the signature expected from a flux rope. It is noted that each excursion of the magnetic field detected by the Orbiter magnetometer was correlated with variations in the three components of the field. A coordinate system is devised which shows that the Venus data is indicative of the presence of flux ropes whose parameters are the coordinates of the system and would yield the excursions observed in the spacecraft crossings of the fields.

Repeated Carbon-Cycle Disturbances at the Permian-Triassic Boundary Separate two Mass Extinctions

NASA Astrophysics Data System (ADS)

Nicol, J. A.; Watson, L.; Claire, M.; Buick, R.; Catling, D. C.

2004-12-01

Non-marine organic matter in Permian-Triassic sediments from the Blue Mountains, eastern Australia shows seven negative δ13C excursions of up to 7%, terminating with a positive excursion of 4%. Fluctuations start at the late Permian Glossopteris floral extinction and continue until just above the palynological Permian-Triassic boundary, correlated with the peak of marine mass extinction. The isotopic fluctuations are not linked to changes in depositional setting, kerogen composition or plant community, so they evidently resulted from global perturbations in atmospheric δ13C and/or CO2. The pattern was not produced by a single catastrophe such as a meteorite impact, and carbon-cycle calculations indicate that gas release during flood-basalt volcanism was insufficient. Methane-hydrate melting can generate a single -7% shift, but cannot produce rapid multiple excursions without repeated reservoir regeneration and release. However, the data are consistent with repeated overturning of a stratified ocean, expelling toxic gases that promoted sequential mass extinctions in the terrestrial and marine realms.

Stable and 'bounded excursion' gravastars, and black holes in Einstein's theory of gravity

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

Rocha, P; Da Silva, M F A; Wang, Anzhong

2008-11-15

Dynamical models of prototype gravastars are constructed and studied. The models are the Visser-Wiltshire three-layer gravastars, in which an infinitely thin spherical shell of a perfect fluid with the equation of state p = (1-{gamma}){sigma} divides the whole spacetime into two regions, where the internal region is de Sitter, and the external one is Schwarzschild. When {gamma}<1 and {Lambda}{ne}0, it is found that in some cases the models represent stable gravastars, and in some cases they represent 'bounded excursion' stable gravastars, where the thin shell is oscillating between two finite radii, while in some other cases they collapse until themore » formation of black holes occurs. However, when {gamma}{>=}1, even with {Lambda}{ne}0, only black holes are found. In the phase space, the region for both stable gravastars and 'bounded excursion' gravastars is very small in comparison to that for black holes, although it is not completely empty.« less

Changes in power and force generation during coupled eccentric-concentric versus concentric muscle contraction with training and aging.

PubMed

Caserotti, Paolo; Aagaard, Per; Puggaard, Lis

2008-05-01

Age-related decline in maximal concentric muscle power is associated with frailty and functional impairments in the elderly. Compared to concentric contraction, mechanical muscle output is generally enhanced when muscles are rapidly pre-stretched (eccentric contraction), albeit less pronounced with increasing age. Exercise has been recommended to prevent loss of muscle power and function and recent guidelines indicate training program for increasing muscle power highly relevant for elderly subjects. This study examined the differences in muscle power, force and movement pattern during concentric-alone and coupled eccentric-concentric contraction and selected functional motor performances before and after 36-week multicomponent training including aerobic, strength, balance, flexibility and coordination components in elderly males. Vertical force, excursion, velocity, power and acceleration of the body center of mass were measured in two standardised vertical jumps (squatting jump, SQJ; countermovement jump, CMJ). Pre-stretch enhancement during CMJ did not improve performance [i.e., no enhanced maximal muscle power (Ppeak) and jump height (JH)] compared to concentric-alone muscle contraction (SQJ). Nevertheless, pre-stretch enhancement occurred as for similar SQJ and CMJ maximal performance, elderly people employed lower mechanical work, higher mean muscle power (Pmean), shorter concentric phase duration and shorter body center of mass displacement during CMJ. Post training, CMJ Ppeak, Pmean and JH increased in training group (P<0.05) while Ppeak and JH decreased in control group during the CMJ and SQJ (P<0.05). In conclusion, long-term training counteracted the age-related decline in muscle power and functional performance observed in the control subjects, while substantial gains in muscular performance were observed in the trained elderly.

Compound-specific carbon isotopes from Earth’s largest flood basalt eruptions directly linked to the end-Triassic mass extinction

PubMed Central

Whiteside, Jessica H.; Olsen, Paul E.; Eglinton, Timothy; Brookfield, Michael E.; Sambrotto, Raymond N.

2010-01-01

A leading hypothesis explaining Phanerozoic mass extinctions and associated carbon isotopic anomalies is the emission of greenhouse, other gases, and aerosols caused by eruptions of continental flood basalt provinces. However, the necessary serial relationship between these eruptions, isotopic excursions, and extinctions has never been tested in geological sections preserving all three records. The end-Triassic extinction (ETE) at 201.4 Ma is among the largest of these extinctions and is tied to a large negative carbon isotope excursion, reflecting perturbations of the carbon cycle including a transient increase in CO2. The cause of the ETE has been inferred to be the eruption of the giant Central Atlantic magmatic province (CAMP). Here, we show that carbon isotopes of leaf wax derived lipids (n-alkanes), wood, and total organic carbon from two orbitally paced lacustrine sections interbedded with the CAMP in eastern North America show similar excursions to those seen in the mostly marine St. Audrie’s Bay section in England. Based on these results, the ETE began synchronously in marine and terrestrial environments slightly before the oldest basalts in eastern North America but simultaneous with the eruption of the oldest flows in Morocco, a CO2 super greenhouse, and marine biocalcification crisis. Because the temporal relationship between CAMP eruptions, mass extinction, and the carbon isotopic excursions are shown in the same place, this is the strongest case for a volcanic cause of a mass extinction to date. PMID:20308590

Uranium isotope evidence for the abrupt onset of oceanic anoxia during the end-Guadalupian mass extinction

NASA Astrophysics Data System (ADS)

Song, H.; Algeo, T. J.; Romaniello, S. J.; Tong, J.; Du, Y.; Wei, H.; Shen, S.; Anbar, A. D.

2016-12-01

The end-Guadalupian (Middle/Late Permian) mass extinction was one of the major crises of the Phanerozoic, resulting in the disappearance of numerous shallow-marine taxa. Several hypotheses have been proposed for this catastrophe but are still under debate. Here, we undertook a high-resolution carbonate U isotopic (δ238/235U) study of the Guadalupian-Lopingian boundary (GLB) at the Penglaitan section (Guadalupian/ Lopingian GSSP) to explore the causal relationship between ocean redox changes and the mass extinction event. The Penglaitan δ238U profile shows two abrupt negative excursions, one in the uppermost Guadalupian (Beds 6j-6k) and the other in the lowermost Lopingian (lower Bed 7). The first excursion (from ‒0.30 ‰ to ‒0.50 ‰) coincided with the main extinction event, suggesting that rapid expansion of oceanic anoxia may have been a contributor to the biotic crisis. The second, larger excursion (from ‒0.25 ‰ to ‒0.65 ‰) demonstrates that the crisis interval was marked by multiple phases of expanded oceanic anoxia. A U-isotope mass balance model shows that, during these excursions, the anoxic/euxinic sink flux increased to 40 % of the total sink flux of seawater U, which is three times of the modern ocean value of 13 %. This study thus provides circumstantial evidence for a causal relationship between expansion of oceanic anoxia and the end-Guadalupian biotic crisis.

Comparison of excursive occlusal force parameters in post-orthodontic and non-orthodontic subjects using T-Scan® III.

PubMed

Qadeer, Sarah; Abbas, Ahmed A; Sarinnaphakorn, Lertrit; Kerstein, Robert B

2018-01-01

Published studies indicate that orthodontically treated patients demonstrate increased posterior occlusal friction contributing to temporomandibular disorder (TMD) symptoms. This study investigated measured excursive movement occlusal contact parameters and their association with TMD symptoms between non- and post-orthodontic subjects. Twenty-five post-orthodontic and 25 non-orthodontic subjects underwent T-Scan® computerized occlusal analysis to determine their disclusion time (DT), the excursive frictional contacts, and occlusal scheme. Each subject answered a TMD questionnaire to determine the presence or absence of TMD symptoms. Statistical analysis compared the within group and between group differences (p < 0.05). Statistically significant differences were observed in the disclusion time: DT = 2.69 s in the post-orthodontic and 1.36 s in the non-orthodontic group. In the non-orthodontic group, 72.7% working and 27.3% non-working side contacts were seen, while in the post-orthodontic group, (near equal) 54.7% working and 45.3% non-working side contacts were seen. Presence of canine guidance was seen in 60% of the non-orthodontic group and 24% in the post-orthodontic group. Seventy-two percent of the post orthodontics subjects presented with one or more TMD symptoms. Significantly longer disclusion time, higher posterior frictional contacts, and more TMD symptoms were observed in the post-orthodontic group, suggesting that orthodontic treatment increases posterior tooth friction. Computerized occlusal analysis is an objective diagnostic tool determining the quality of excursive movements following orthodontic treatment.

Effect of a new hypoglycemic agent, A-4166 [(-)-N-(trans-4-isopropylcyclohexanecarbonyl)-D-phenylalanine], on postprandial blood glucose excursion: comparison with voglibose and glibenclamide.

PubMed

Ikenoue, T; Okazaki, K; Fujitani, S; Tsuchiya, Y; Akiyoshi, M; Maki, T; Kondo, N

1997-04-01

(-)-N-(trans-4-Isopropylcyclohexanecarbonyl)-D-phenylalanine (A-4166) is a new nonsulfonylurea hypoglycemic agent that lowers blood glucose by stimulating insulin release. In the present study, we examined the effects of A-4166, voglibose (an alpha-glucosidase inhibitor), and glibenclamide (a sulfonylurea) on the postprandial glycemic increase in rats with or without diabetes mellitus. Oral administration of A-4166 (25-100 mg/kg) dose-dependently decreased blood glucose with a rapid onset and short duration in normal rats. On the other hand, glibenclamide (1-4 mg/kg) showed a slower onset of its hypoglycemic action, and voglibose (0.2 mg/kg) had no effect. In the case of postprandial glucose excursion, the carbohydrate-induced increase in blood glucose was reduced by oral administration of either A-4166 or voglibose without causing sustained hypoglycemia in both normal and neonatal streptozotocin-induced diabetic rats. However, the efficacy of voglibose varied with the type of carbohydrate load. Glibenclamide produced a prolonged decrease in blood glucose without any appreciable effect on the initial glucose excursion. After sucrose loading, plasma insulin levels during the initial 1 h were significantly higher in A-4166-treated rats than in control rats, while voglibose completely inhibited the insulin response to sucrose. In glibenclamide-treated rats, an augmented insulin response was not seen. In conclusion, unlike other hypoglycemic agents, A-4166 suppresses postprandial glucose excursions by stimulating the early phase of insulin secretion.

Middle-Upper Permian carbon isotope stratigraphy at Chaotian, South China: Pre-extinction multiple upwelling of oxygen-depleted water onto continental shelf

NASA Astrophysics Data System (ADS)

Saitoh, Masafumi; Isozaki, Yukio; Ueno, Yuichiro; Yoshida, Naohiro; Yao, Jianxin; Ji, Zhansheng

2013-05-01

In order to examine the causal relationships between the carbon cycle in a shallow euphotic zone and the environmental changes in a relatively deep disphotic zone at the end-Guadalupian (Middle Permian), isotopic compositions of carbonate carbon (δ13Ccarb) of the Guadalupian-Lopingian (Upper Permian) rocks were analyzed in the Chaotian section in northern Sichuan, South China. By analyzing exceptionally fresh drill core samples, a continuous chemostratigraphic record was newly obtained. The ca. 65 m-thick analyzed carbonate rocks at Chaotian comprise three stratigraphic units, i.e., the Limestone Unit of the Guadalupian Maokou Formation, the Mudstone Unit of the Maokou Formation, and the lower part of the Wuchiapingian (Lower Lopingian) Wujiaping Formation, in ascending order. The Limestone Unit of the Maokou Formation is characterized by almost constant δ13Ccarb values of ca. +4‰ followed by an abrupt drop for 7‰ to -3‰ in the topmost part of the unit. In the Mudstone Unit of the Maokou Formation, the δ13Ccarb values are rather constant around +2‰, although distinct three isotopic negative excursions for 3‰ from ca. +2 to -1‰ occurred in the upper part of the unit. In the lower part of the Wujiaping Formation, the δ13Ccarb values monotonously increase for 5‰ from ca. 0 to +5‰. The present data newly demonstrated four isotopic negative excursions in the topmost part of the Maokou Formation in the Capitanian (Late Guadalupian) at Chaotian. It is noteworthy that these negative excursions are in accordance with the emergence of an oxygen-depleted condition on the relatively deep disphotic slope/basin on the basis of litho- and bio-facies characteristics. They suggest multiple upwelling of oxygen-depleted waters with dissolved inorganic carbon of relatively low carbon isotope values along the continental margin, from the deeper disphotic slope/basin to the shallower euphotic shelf, slightly before the end-Guadalupian extinction. Although the negative excursions at Chaotian are apparently correlated with the previously proposed large negative excursion in the middle Capitanian in South China, the age difference according to the biostratigraphic constraints clearly exclude this interpretation. The isotopic negative excursions at Chaotian are unique and no similar isotopic signal in the same period has been reported elsewhere. The multiple upwelling of oxygen-depleted waters onto the euphotic shelf may have represented local phenomena that occurred solely around northwestern South China.

Posttest examination results of recent treat tests on metal fuel

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

Holland, J.W.; Wright, A.E.; Bauer, T.H.

A series of in-reactor transient tests is underway to study the characteristics of metal-alloy fuel during transient-overpower-without-scam conditions. The initial tests focused on determining the margin to cladding breach and the axial fuel motions that would mitigate the power excursion. The tests were conducted in flowing-sodium loops with uranium - 5% fissium EBR-II Mark-II driver fuel elements in the TREAT facility. Posttest examination of the tests evaluated fuel elongation in intact pins and postfailure fuel motion. Microscopic examination of the intact pins studied the nature and extent of fuel/cladding interaction, fuel melt fraction and mass distribution, and distribution of porosity.more » Eutectic penetration and failure of the cladding were also examined in the failed pins.« less

Correlation of electrical reactor cable failure with materials degradation

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

Stuetzer, O.M.

1986-03-01

Complete circuit failure (shortout) of electrical cables typically used in nuclear power plant containments is investigated. Failure modes are correlated with the mechanical deterioration of the elastomeric cable materials. It is found that for normal reactor operation, electrical cables are reliable and safe over very long periods. During high temperature excursions, however, cables pulled across corners under high stress may short out due to conductor creep. Severe cracking will occur in short times during high temperatures (>150/sup 0/C) and in times of the order of years at elevated temperatures (100/sup 0/C to 140/sup 0/C). A theoretical treatment of stress distributionmore » responsible for creep and for cracking by J.E. Reaugh of Science Applications, Inc. is contained in the Appendix. 29 refs., 32 figs.« less

Cyclic and low temperature effects on microcircuits

NASA Technical Reports Server (NTRS)

Weissflug, V. A.; Sisul, E. V.

1977-01-01

Cyclic temperature and low temperature operating life tests, and pre-/post-life device evaluations were used to determine the degrading effects of thermal environments on microcircuit reliability. Low power transistor-transistor-logic gates and linear devices were included in each test group. Device metallization systems included aluminum metallization/aluminum wire, aluminum metallization/gold wire, and gold metallization/gold wire. Fewer than 2% electrical failures were observed during the cyclic and low temperature life tests and the post-life evaluations revealed approximately 2% bond pull failures. Reconstruction of aluminum die metallization was observed in all devices and the severity of the reconstruction appeared to be directly related to the magnitude of the temperature excursion. All types of bonds except the gold/gold bonds were weakened by exposure to repeated cyclic temperature stress.

The Role of Arch Compression and Metatarsophalangeal Joint Dynamics in Modulating Plantar Fascia Strain in Running

PubMed Central

McDonald, Kirsty A.; Stearne, Sarah M.; Alderson, Jacqueline A.; North, Ian; Pires, Neville J.; Rubenson, Jonas

2016-01-01

Elastic energy returned from passive-elastic structures of the lower limb is fundamental in lowering the mechanical demand on muscles during running. The purpose of this study was to investigate the two length-modulating mechanisms of the plantar fascia, namely medial longitudinal arch compression and metatarsophalangeal joint (MPJ) excursion, and to determine how these mechanisms modulate strain, and thus elastic energy storage/return of the plantar fascia during running. Eighteen runners (9 forefoot and 9 rearfoot strike) performed three treadmill running trials; unrestricted shod, shod with restricted arch compression (via an orthotic-style insert), and barefoot. Three-dimensional motion capture and ground reaction force data were used to calculate lower limb kinematics and kinetics including MPJ angles, moments, powers and work. Estimates of plantar fascia strain due to arch compression and MPJ excursion were derived using a geometric model of the arch and a subject-specific musculoskeletal model of the plantar fascia, respectively. The plantar fascia exhibited a typical elastic stretch-shortening cycle with the majority of strain generated via arch compression. This strategy was similar in fore- and rear-foot strike runners. Restricting arch compression, and hence the elastic-spring function of the arch, was not compensated for by an increase in MPJ-derived strain. In the second half of stance the plantar fascia was found to transfer energy between the MPJ (energy absorption) and the arch (energy production during recoil). This previously unreported energy transfer mechanism reduces the strain required by the plantar fascia in generating useful positive mechanical work at the arch during running. PMID:27054319

The Role of Arch Compression and Metatarsophalangeal Joint Dynamics in Modulating Plantar Fascia Strain in Running.

PubMed

McDonald, Kirsty A; Stearne, Sarah M; Alderson, Jacqueline A; North, Ian; Pires, Neville J; Rubenson, Jonas

2016-01-01

Elastic energy returned from passive-elastic structures of the lower limb is fundamental in lowering the mechanical demand on muscles during running. The purpose of this study was to investigate the two length-modulating mechanisms of the plantar fascia, namely medial longitudinal arch compression and metatarsophalangeal joint (MPJ) excursion, and to determine how these mechanisms modulate strain, and thus elastic energy storage/return of the plantar fascia during running. Eighteen runners (9 forefoot and 9 rearfoot strike) performed three treadmill running trials; unrestricted shod, shod with restricted arch compression (via an orthotic-style insert), and barefoot. Three-dimensional motion capture and ground reaction force data were used to calculate lower limb kinematics and kinetics including MPJ angles, moments, powers and work. Estimates of plantar fascia strain due to arch compression and MPJ excursion were derived using a geometric model of the arch and a subject-specific musculoskeletal model of the plantar fascia, respectively. The plantar fascia exhibited a typical elastic stretch-shortening cycle with the majority of strain generated via arch compression. This strategy was similar in fore- and rear-foot strike runners. Restricting arch compression, and hence the elastic-spring function of the arch, was not compensated for by an increase in MPJ-derived strain. In the second half of stance the plantar fascia was found to transfer energy between the MPJ (energy absorption) and the arch (energy production during recoil). This previously unreported energy transfer mechanism reduces the strain required by the plantar fascia in generating useful positive mechanical work at the arch during running.

First spacecraft encounter with an asteroid approaches

NASA Technical Reports Server (NTRS)

Tholen, David J.

1991-01-01

During the course of the Galileo spacecraft's journey to Jupiter it will make two excursions through the steroid belt situated between Mars and Jupiter. The first excursion involves an encounter with the asteroid 951 Gaspra, which will take place on October 29, 1991. Gaspra is a small (about 15 km diameter) asteroid near the outer edge of the main asteroid belt. It's spectral classification is S, suggesting a composition similar to those of stony-iron meteorites. A figure is given showing the brightness of this asteroid as a function of time.

Design, fabrication, and testing of energy-harvesting thermoelectric generator

NASA Astrophysics Data System (ADS)

Jovanovic, Velimir; Ghamaty, Saeid

2006-03-01

An energy-harvesting thermoelectric generator (TEG) is being developed to provide power for wireless sensors used in health monitoring of Navy machinery. TEGs are solid-state devices that convert heat directly into electricity without any moving parts. In this application, the TEGs utilize the heat transfer between shipboard waste heat sources and the ambient air to generate electricity. In order to satisfy the required small design volume of less than one cubic inch, Hi-Z is using its innovative thin-film Quantum Well (QW) thermoelectric technology that will provide a factor of four increase in efficiency and a large reduction in the device volume over the currently used bulk Bi IITe 3 based thermoelectics. QWs are nanostructured multi-layer films. These wireless sensors can be used to detect cracks, corrosion, impact damage, and temperature and vibration excursions as part of the Condition Based Maintenance (CBM) of the Navy ship machinery. The CBM of the ship machinery can be significantly improved by automating the process with the use of self-powered wireless sensors. These power-harvesting TEGs can be used to replace batteries as electrical power sources and to eliminate power cables and data lines. The first QW TEG module was fabricated and initial tests were successful. It is planned to conduct performance tests the entire prototype QW TEG device (consisting of the TEG module, housing, thermal insulation and the heat sink) in a simulated thermal environment of a Navy ship.

Ultra-long fiber Raman lasers: design considerations

NASA Astrophysics Data System (ADS)

Koltchanov, I.; Kroushkov, D. I.; Richter, A.

2015-03-01

In frame of the European Marie Currie project GRIFFON [http://astonishgriffon.net/] the usage of a green approach in terms of reduced power consumption and maintenance costs is envisioned for long-span fiber networks. This shall be accomplished by coherent transmission in unrepeatered links (100 km - 350 km) utilizing ultra-long Raman fiber laser (URFL)-based distributed amplification, multi-level modulation formats, and adapted Digital Signal Processing (DSP) algorithms. The URFL uses a cascaded 2-order pumping scheme where two (co- and counter-) ˜ 1365 nm pumps illuminate the fiber. The URFL oscillates at ˜ 1450 nm whereas amplification is provided by stimulated Raman scattering (SRS) of the ˜ 1365 nm pumps and the optical feedback is realized by two Fiber Bragg gratings (FBGs) at the fiber ends reflecting at 1450 nm. The light field at 1450 nm provides amplification for signal waves in the 1550 nm range due to SRS. In this work we present URFL design studies intended to characterize and optimize the power and noise characteristics of the fiber links. We use a bidirectional fiber model describing propagation of the signal, pump and noise powers along the fiber length. From the numerical solution we evaluate the on/off Raman gain and its bandwidth, the signal excursion over the fiber length, OSNR spectra, and the accumulated nonlinearities. To achieve best performance for these characteristics the laser design is optimized with respect to the forward/backward pump powers and wavelengths, input/output signal powers, reflectivity profile of the FBGs and other parameters.

Evaluation of the Inertial Response of Variable-Speed Wind Turbines Using Advanced Simulation

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

Scholbrock, Andrew K; Muljadi, Eduard; Gevorgian, Vahan

In this paper, we focus on the temporary frequency support effect provided by wind turbine generators (WTGs) through the inertial response. With the implemented inertial control methods, the WTG is capable of increasing its active power output by releasing parts of the stored kinetic energy when the frequency excursion occurs. The active power can be boosted temporarily above the maximum power points, but the rotor speed deceleration follows and an active power output deficiency occurs during the restoration of rotor kinetic energy. We evaluate and compare the inertial response induced by two distinct inertial control methods using advanced simulation. Inmore » the first stage, the proposed inertial control methods are analyzed in offline simulation. Using an advanced wind turbine simulation program, FAST with TurbSim, the response of the researched wind turbine is comprehensively evaluated under turbulent wind conditions, and the impact on the turbine mechanical components are assessed. In the second stage, the inertial control is deployed on a real 600kW wind turbine - Controls Advanced Research Turbine, 3-bladed (CART3), which further verifies the inertial control through a hardware-in-the-loop (HIL) simulation. Various inertial control methods can be effectively evaluated based on the proposed two-stage simulation platform, which combines the offline simulation and real-time HIL simulation. The simulation results also provide insights in designing inertial control for WTGs.« less

Investigating The Kinematics of Canids and Felids

NASA Astrophysics Data System (ADS)

Sur, D.

2016-12-01

For all organisms, metabolic energy is critical for survival. While moving efficiently is a necessity for large carnivores, the influence of kinematics on energy demand remains poorly understood. We measured the kinematics of dogs, wolves, and pumas to detect any differences in their respective energy expenditures. Using 22 kinematic parameters measured on 78 videos, we used one-way ANOVAs and paired T-tests to compare 5 experimental treatments among gaits in dogs (n=11 in 3 breed groups), wolves (n=2), and pumas (n=2). Across the measured parameters, we found greater kinematic similarity than expected among dog breeds and no trend in any of the 22 parameters regarding the effect of steepness on locomotion mechanics. Similarly, treadmill kinematics were nearly identical to those measured during outdoor movement. However, in 3 inches of snow, we observed significant differences (p<0.05) in 5 of the 22 parameters for one wolf. When comparing canids (wolves and dogs) to a felid (pumas), we found that pumas and dogs are the most kinematically distinct (differing in 13 of 22 parameters, compared with 5 of 22 for wolves and pumas). Lastly, compared with wolves, walking pumas had larger head angles (p=0.0025), forelimb excursion angles (p=0.0045), and hindlimb excursion angles (p=0.0327). After comparing the energetics of pumas and dogs with their respective kinematics, we noted that less dynamic kinematics result in energy savings. Through tracking the locations and gait behavior of large carnivores, novel sensor technology can reveal how indoor kinematics applies to wild animals and improve the conservation of these species.

The study of the geomagnetic excursions and the relative intensities from Chinese loess 10Be over the past 130 ka

NASA Astrophysics Data System (ADS)

Zhou, W.; Xian, F.; Beck, J.; An, Z.; Wu, Z.; Liu, M.; Chen, M.; Priller, A.; Kutschera, W.; Jull, A. T.; Yu, H.; Song, S.; Cheng, P.; Kong, X.

2009-12-01

Chinese loess is well-known archive for the paleogeomagnetic and paleoclimatic studies [Zhou et al., 1990; An et al., 1990; Zhu et al., 2007]. However, earlier efforts to extract weak geomagnetic excursion signals from Chinese loess 10Be were always unsuccessful due to the complexities of loess 10Be, which results in the fact that loess 10Be was only used as a climatic proxy [Shen et al., 1992; Beer et al.,1993; Gu et al.,1996]. Meanwhile, knowledge on the precise stratigraphic horizons of geomagnetic excursions with a reliable dating [Channell, 2006], on whether the short-lived excursions such as Blake can not be recorded in paleosol unit are still controversial. Here, we present the reconstructed past 130ka geomagnetic excursions and relative paleointensities for the first time from 10Be records in two Chinese loess sections. Results are comparative with those of independent geomagnetic research on Atlantic and Pacific sediments. The derived Laschamp and Blake events lie in the loess-paleosol (L1SS1 and S1SS3) corresponding to mid MIS 3 and 5e respectively. Our studies prove the potential application of the complex loess 10Be for long-term geomagnetic tracing and provide new evidence to answer the long-existing debates on the precise stratigraphic horizon of geomagnetic excursions. Our study suggests the potential application of loess-paleosol 10Be for reconstructing geomagnetic intensity variations spanning the whole Quaternary. References 1. Zhou, L. P., F. Oldfield, A. G. Wintle, S. G. Robinson, and J. T. Wang (1990), Partly pedogenic origin of magnetic variations in Chinese loess, Nature, 346, 737-739. 2. An, Z. S., T. S. Liu, Y. C. Lu, S. C. Porter, G. Kukla, X. H. Wu, and Y. M. Hua (1990), The long-term paleomonsoon variation recorded by the loess-paleosol sequence in Central China, Quat. Int., 7-8, 91-95. 3. Zhu, R. X., R. Zhang, C. L. Deng, Y. X. Pan, Q. S. Liu, and Y. B. Sun (2007), Are Chinese loess deposits essentially continuous?, Geophys. Res. Lett., 34, L17306. 4. Shen, C. D., J. Beer, T. S. Liu, H. Oeschger, G. Bonani, M. Suter, and W.Wolfli (1992), 10Be in Chinese loess, Earth Planet. Sci. Lett., 109(1-2), 169-177. 5. Gu, Z. Y., D. Lal, T. S. Liu, J. Southon, M. W. Caffee, Z. T. Guo, and M. Y.Chen (1996), Five million year 10Be record in Chinese loess and red-clay: climate and weathering relationships, Earth Planet. Sci. Lett., 144(1-2), 273-287. 6. Beer, J., C. D. Shen, F. Heller ,T.S. Liu, G. Bonani, B. Dittrich, M. Suter, and P.W. Kubik (1993), 10Be and magnetic susceptibility in Chinese Loess, Geophys. Res. Lett., 20(1), 57-60 7. Channell, J. E. T.(2006), Late Brunhes polarity excursions (Mono Lake, Laschamp, Iceland Basin and Pringle Falls) recorded at ODP Site 919 (Irminger Basin), Earth Planet. Sci. Lett., 244(1-2), 378-393.

Fractionation between inorganic and organic carbon during the Lomagundi (2.22 2.1 Ga) carbon isotope excursion

NASA Astrophysics Data System (ADS)

Bekker, A.; Holmden, C.; Beukes, N. J.; Kenig, F.; Eglinton, B.; Patterson, W. P.

2008-07-01

The Lomagundi (2.22-2.1 Ga) positive carbon isotope excursion in shallow-marine sedimentary carbonates has been associated with the rise in atmospheric oxygen, but subsequent studies have demonstrated that the carbon isotope excursion was preceded by the rise in atmospheric oxygen. The amount of oxygen released to the exosphere during the Lomagundi excursion is constrained by the average global fractionation between inorganic and organic carbon, which is poorly characterized. Because dissolved inorganic and organic carbon reservoirs were arguably larger in the Paleoproterozoic ocean, at a time of lower solar luminosity and lower ocean redox state, decoupling between these two variables might be expected. We determined carbon isotope values of carbonate and organic matter in carbonates and shales of the Silverton Formation, South Africa and in the correlative Sengoma Argillite Formation, near the border in Botswana. These units were deposited between 2.22 and 2.06 Ga along the margin of the Kaapvaal Craton in an open-marine deltaic setting and experienced lower greenschist facies metamorphism. The prodelta to offshore marine shales are overlain by a subtidal carbonate sequence. Carbonates exhibit elevated 13C values ranging from 8.3 to 11.2‰ vs. VPDB consistent with deposition during the Lomagundi positive excursion. The total organic carbon (TOC) contents range from 0.01 to 0.6% and δ13C values range from - 24.8 to - 13.9‰. Thus, the isotopic fractionation between organic and carbonate carbon was on average 30.3 ± 2.8‰ ( n = 32) in the shallow-marine environment. The underlying Sengoma shales have highly variable TOC contents (0.14 to 21.94%) and δ13C values (- 33.7 to - 20.8‰) with an average of - 27.0 ± 3.0‰ ( n = 50). Considering that the shales were also deposited during the Lomagundi excursion, and taking δ13C values of the overlying carbonates as representative of the δ13C value of dissolved inorganic carbon during shale deposition, a carbon isotope fractionation as large as ~ 37‰ appears to characterize the production of bulk organic matter in the deeper part of the Pretoria Basin at that time. This enhanced fractionation relative to that observed in shallow-water environments likely reflects heterotrophic (secondary) and chemotrophic productivity at and below a pronounced redoxcline, consistent with the euxinic conditions inferred from independent evidence for the deeper part of the Pretoria Basin. Greater variability in organic carbon vs. carbonate carbon isotopic values on the shallow-marine carbonate platform suggests that the carbon cycling was dominated by a large dissolved inorganic carbon reservoir during the Lomagundi excursion. Our study suggests that in contrast to the Late Neoproterozoic and Phanerozoic, when carbon isotope fractionation between carbonate and organic carbon in the open ocean was mostly controlled by primary producers, in the Paleoproterozoic redox-stratified ocean heterotrophic and chemotrophic productivity overprinted a signal of primary productivity below the redoxcline. This strong imprint of heterotrophic and chemotrophic productivity on organic carbon isotope records complicates the reconstruction of spatial patterns and secular trends in the δ13C values of dissolved inorganic carbon in the Paleoproterozoic seawater.

Heat Transfer Issues in Finite Element Analysis of Bounding Accidents in PPCS Models

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

Pampin, R.; Karditsas, P.J.

2005-05-15

Modelling of temperature excursions in structures of conceptual power plants during hypothetical worst-case accidents has been performed within the European Power Plant Conceptual Study (PPCS). A new, 3D finite elements (FE) based tool, coupling the different calculations to the same tokamak geometry, has been extensively used to conduct the neutron transport, activation and thermal analyses for all PPCS plant models. During a total loss of cooling, the usual assumption for the bounding accident, passive removal of the decay heat from activated materials depends on conduction and radiation heat exchange between components. This paper presents and discusses results obtained during themore » PPCS bounding accident thermal analyses, examining the following issues: (a) radiation heat exchange between the inner surfaces of the tokamak, (b) the presence of air within the cryostat volume, and the heat flow arising from the circulation pattern provided by temperature differences between various parts, and (c) the thermal conductivity of pebble beds, and its degradation due to exposure to neutron irradiation, affecting the heat transfer capability and thermal response of a blanket based on these components.« less

DEVICE FOR CONTROLLING INSERTION OF ROD

DOEpatents

Beaty, B.J.

1958-10-14

A device for rapidly inserting a safety rod into a nuclear reactor upon a given signal or in the event of a power failure in order to prevent the possibility of extensive damage caused by a power excursion is described. A piston is slidably mounted within a vertical cylinder with provision for an electromagnetic latch at the top of the cylinder. This assembly, with a safety rod attached to the piston, is mounted over an access port to the core region of the reactor. The piston is normally latched at the top of the cylinder with the safety rod clear of the core area, however, when the latch is released, the piston and rod drop by their own weight to insert the rod. Vents along the side of the cylinder permit the escape of the air entrapped under the piston over the greater part of the distance, however, at the end of the fall the entrapped air is compressed thereby bringing the safety rod gently to rest, thus providing for a rapid automatic insertion of the rod with a minimum of structural shock.

Postmeal exercise blunts postprandial glucose excursions in people on metformin monotherapy.

PubMed

Erickson, Melissa L; Little, Jonathan P; Gay, Jennifer L; McCully, Kevin K; Jenkins, Nathan T

2017-08-01

Metformin is used clinically to reduce fasting glucose with minimal effects on postprandial glucose. Postmeal exercise reduces postprandial glucose and may offer additional glucose-lowering benefit beyond that of metformin alone, yet controversy exists surrounding exercise and metformin interactions. It is currently unknown how postmeal exercise and metformin monotherapy in combination will affect postprandial glucose. Thus, we examined the independent and combined effects of postmeal exercise and metformin monotherapy on postprandial glucose. A randomized crossover design was used to assess the influence of postmeal exercise on postprandial glucose excursions in 10 people treated with metformin monotherapy (57 ± 10 yr, HbA 1C  = 6.3 ± 0.6%). Each participant completed the following four conditions: sedentary and postmeal exercise (5 × 10-min bouts of treadmill walking at 60% V̇o 2max ) with metformin and sedentary and postmeal exercise without metformin. Peak postprandial glucose within a 2-h time window and 2-h total area under the curve was assessed after a standardized breakfast meal, using continuous glucose monitoring. Postmeal exercise significantly blunted 2-h peak ( P = 0.001) and 2-h area under the curve ( P = 0.006), with the lowest peak postprandial glucose excursion observed with postmeal exercise and metformin combined ( P < 0.05 vs. all other conditions: metformin/sedentary: 12 ± 3.4, metformin/exercise: 9.7 ± 2.3, washout/sedentary: 13.3 ± 3.2, washout/exercise: 11.1 ± 3.4 mmol/l). Postmeal exercise and metformin in combination resulted in the lowest peak postprandial glucose excursion compared with either treatment modality alone. Exercise timed to the postprandial phase may be important for optimizing glucose control during metformin monotherapy. NEW & NOTEWORTHY The interactive effects of metformin and exercise on key physiological outcomes remain an area of controversy. Findings from this study show that the combination of metformin monotherapy and moderate-intensity postmeal exercise led to beneficial reductions in postprandial glucose excursions. Postmeal exercise may be a useful strategy for the management of postprandial glucose in people on metformin. Copyright © 2017 the American Physiological Society.

Glycemic excursions are positively associated with HbA1c reduction from baseline after treatment with acarbose in patients with type 2 diabetes on metformin monotherapy.

PubMed

Wang, Jun-Sing; Lee, I-Te; Lee, Wen-Jane; Lin, Shi-Dou; Su, Shih-Li; Tu, Shih-Te; Tseng, Yao-Hsien; Lin, Shih-Yi; Sheu, Wayne Huey-Herng

2017-03-01

The aim of the present study was to examine the association between glycemic excursions before treatment and HbA1c reduction after treatment intensification with acarbose or glibenclamide in patients with type 2 diabetes (T2D). Patients receiving single or dual oral antidiabetic drug treatment with an HbA1c of 7.0-11.0 % (53-97 mmol/mol) were switched to metformin monotherapy (500 mg, t.i.d.) for 8 weeks, followed by randomization to either acarbose (100 mg, t.i.d.) or glibenclamide (5 mg, t.i.d.) as add-on treatment for 16 weeks. Glycemic excursions were assessed as mean amplitude of glycemic excursions (MAGE) with 72-h ambulatory continuous glucose monitoring. Treatment efficacy was evaluated as relative HbA1c reduction (%), calculated as (baseline HbA1c - post-treatment HbA1c)/baseline HbA1c × 100. Fifty patients (mean [±SD] age 53.5 ± 8.2 years, 48 % men, mean baseline HbA1c 8.4 ± 1.2 %) were analyzed. Baseline MAGE was positively correlated with relative HbA1c reduction from baseline in patients treated with acarbose (r = 0.421, P = 0.029) but not glibenclamide (r = 0.052, P = 0.813). Linear regression analysis revealed that the association between baseline MAGE and relative HbA1c reduction from baseline (β = 0.125, P = 0.029) in patients treated with acarbose remained significant after adjustment for several confounders (P < 0.05 for all models). In patients with T2D on metformin monotherapy, baseline MAGE was positively correlated with relative HbA1c reduction from baseline after treatment with acarbose, but not glibenclamide. These findings highlight the importance of glycemic excursions in individualized treatment for patients with T2D. © 2016 Ruijin Hospital, Shanghai JiaoTong University School of Medicine (SJTU), Chinese Society of Endocrinology and Chinese Endocrinologist Association and John Wiley & Sons Australia, Ltd.

Prognostic value of early in-hospital glycemic excursion in elderly patients with acute myocardial infarction.

PubMed

Su, Gong; Mi, Shu-hua; Li, Zhao; Tao, Hong; Yang, Hong-xia; Zheng, Hong

2013-02-11

Acute phase hyperglycemia has been associated with increased mortality in patients with acute myocardial infarction (AMI). However, the predictive value of glycemic excursion for adverse outcome in elderly AMI patients is not clear. The aim of this study is to investigate the prognostic value of early in-hospital glycemic excursion and hemoglobin A1c (HbA1c) for one-year major adverse cardiac event (MACE) in elderly patients with AMI. We studied 186 elderly AMI patients, whose clinical data were collected and the Global Registry of Acute Coronary Events (GRACE) risk score were calculated on admission. The fluctuations of blood glucose in patients were measured by a continuous glucose monitoring system (CGMS) for 72 hours. Participants were grouped into tertiles of mean amplitude of glycemic excursions (MAGE) and grouped into HbA1c levels (as ≥6.5% or <6.5%). The MACE of patients, including new-onset myocardial infarction, acute heart failure and cardiac death, was documented during one year follow-up. The relationship of MAGE and HbA1c to the incidence of MACE in elderly AMI patients was analyzed. In all participants, a higher MAGE level was associated with the higher GRACE score (r = 0.335, p < 0.001). The rate of MACE by MAGE tertiles (>3.94 mmol/L, 2.55-3.94 mmol/L or <2.55 mmol/L) was 30.2% vs. 14.8% vs. 8.1%, respectively (p = 0.004); by HbA1c category (≥6.5% vs. <6.5%) was 22.7% vs. 14.4%, respectively (p = 0.148). Elderly AMI patients with a higher MAGE level had a significantly higher cardiac mortality. In multivariable analysis, high MAGE level was significantly associated with incidence of MACE (HR 3.107, 95% CI 1.190-8.117, p = 0.021) even after adjusting for GRACE risk score, but HbA1c was not. The early in-hospital intraday glycemic excursion may be an important predictor of mortality and MACE even stronger than HbA1c in elderly patients after AMI.

Parallel δ 13C and Conifer Physiognomic Trends Across the Triassic-Jurassic Boundary

NASA Astrophysics Data System (ADS)

Whiteside, J. H.; Olsen, P. E.; Sambrotto, R. N.; Cornet, B.

2003-12-01

The Triassic-Jurassic mass extinction event ( ˜200 Ma) had a profound effect on biotic evolution, and herein we describe trends in cheirolepidaceous conifer leaf physiognomy from the Pangean tropics (present northeastern USA) that at least broadly parallel a negative δ 13C excursion recorded in the same strata. The physiognomic changes appear at an abrupt (<10 ky) negative carbon isotope excursion (1) synchronous with a previously described palynological extinction level, fern spike, and Ir anomaly (2), and continue through a prolonged negative excursion, lasting 900 ky (through all three CAMP basaltic extrusive events), encompassing most of the Hettangian age. The physiognomic changes seen in the cheirolepidaceous conifer leafy shoot forms Brachyphyllum and Pagiophyllum through the δ 13C excursions include primarily the development of microphyllous leaves with thickened cuticle and sunken papillate stomata (3). These floral modifications are consistent with intense thermal stress plausibly due to very high atmospheric CO2 concentrations and corroborate McElwain's (4) thermal damage hypothesis for the Triassic-Jurassic transition that was originally based on different plant taxa from the higher Pangean latitudes in present Greenland and Sweden. Subsequently, a 2- to 5-fold increase in the area of leafy shoots in strata of latest Hettangian age suggest a return to lower thermal stress levels perhaps due to lower CO2, despite the fact that eastern North America continued to drift into more arid latitudes. The floral physiognomic changes associated with the negative δ 13C excursion and likely very elevated CO2 levels is in many ways a microcosm of the Mesozoic in which the dominance of cheiroleps apparently overlaps with the highest CO2 levels of the Mesozoic (5). References. (1) Whiteside JH, Olsen PE, Sambrotto RN. 2003. Geol. Soc. Amer. Abst. Prog. (in press). (2) Olsen PE et al., Science 296:1305-1307 (3) Cornet B. 1989. in Olsen PE, Schlische RW, Gore PJW, Internat. Geol. Cong., Guidebooks T351, p. 115. (4) McElwain JC, Beerling, DJ, Woodward FI. 1999. Science 285:1386. (5) Ekart D, Cerling TR, Montanez IP, Tabor NJ. 1999. Am. J. Sci. 299:805.

Manifestation of the geomagnetic Mono Lake excursion in sediments of the northern part of the Barents Sea

NASA Astrophysics Data System (ADS)

Goos'kova, E.; Volkova, Y.; Piskarev, A.; Morner, N.-A.; Abrahamsen, N.; Dergachev, V.; Raspopov, O.

2003-04-01

Palaeomagnetic characteristics of cores from three boreholes (AK-56, AK-87, AK-98) collected in the northern part of the Barents sea (79-80 N) during the expedition of the Research Vessel "Academician Karpinsky" in 1998 have been studied. The cores were taken from depths of 329, 377, and 473 m, respectively. In all three cores, changes in inclination from -80 to -150 degrees were observed at a depth of 110-130 cm (in 6-8 core samples), which suggests that this phenomenon can be attributed to a geomagnetic field excursion. Basing on dating of the lithologic Holocene-Pleistocene boundary, the sedimentation rate in this part of the Barents Sea can be estimated to be 5-7 cm/1000 years. In this case the age of the excursion is about 24 000 BP, i.e., it corresponds to the Mono Lake excursion. In the Barents Sea sediments, the manifestation of this excursion was revealed for the first time in the ACB-2 core taken in the central part of the sea. At a depth of 150-180 cm, all three cores (in 8-10 samples) were found to have a layer with abnormally high natural remanent magnetization (up to 6-11 nT with a mean value of 1.5 nT) and magnetic susceptibility (up to 1.0-1.7 x 10-3 SI with a mean value of 0.4 x 10-3 SI). Basing on lithological data, the time of formation of this layer can be estimated as approximately 30 000 - 35 000 BP. A reference layer at the depth corresponding to the Holocene-Pleistocene boundary with similar changes in magnetic susceptibility attributed to climate change was found in the cores taken from the central part of the Barents sea earlier. It is likely that sharp changes in magnetic properties of sediments in the northern part of the Barents Sea about 30 000 - 35 000 BP are also attributable to a sharp climate change (warming) during that period of time. This work was supported by INTAS, Grant 97-31008 and PFBR, Grant 00-05-64921.

Prognostic Value of Right Ventricular Dysfunction in Heart Failure With Reduced Ejection Fraction: Superiority of Longitudinal Strain Over Tricuspid Annular Plane Systolic Excursion.

PubMed

Carluccio, Erberto; Biagioli, Paolo; Alunni, Gianfranco; Murrone, Adriano; Zuchi, Cinzia; Coiro, Stefano; Riccini, Clara; Mengoni, Anna; D'Antonio, Antonella; Ambrosio, Giuseppe

2018-01-01

In heart failure (HF) with reduced ejection fraction, right ventricular (RV) impairment, as defined by reduced tricuspid annular plane systolic excursion, is a predictor of poor outcome. However, peak longitudinal strain of RV free wall (RVFWS) has been recently proposed as a more accurate and sensitive tool to evaluate RV function. Accordingly, we investigated whether RVFWS could help refine prognosis of patients with HF with reduced ejection fraction in whom tricuspid annular plane systolic excursion is still preserved. A total of 200 patients with HF with reduced ejection fraction (age, 66±11 years; ejection fraction, 30±7%) with preserved tricuspid annular plane systolic excursion (>16 mm) underwent RV function assessment using speckle-tracking echocardiography to measure peak RVFWS. After a median follow-up period of 28 months, 62 (31%) patients reached the primary composite end point of all-cause death/HF rehospitalization. Median RVFWS was -19.3% (interquartile range, -23.3% to -15.0%). By lasso-penalized Cox-hazard model, RVFWS was an independent predictor of outcome, along with Eplerenone in Mild Patients Hospitalization and Survival Study in Heart Failure-HF score, Echo-HF score, and severe mitral regurgitation. The best cutoff value of RVFWS for prediction of outcome was -15.3% (area under the curve, 0.68; P <0.001; sensitivity, 50%; specificity, 80%). In 50 patients (25%), RVFWS was impaired (ie, ≥-15.3%); event rate (per 100 patients per year) was greater in them than in patients with RVFWS <-15.3% (29.5% [95% confidence interval, 20.4-42.7] versus 9.4% [95% confidence interval, 6.7-13.1]; P <0.001). RVFWS yielded a significant net reclassification improvement (0.584 at 3 years; P <0.001), with 68% of nonevents correctly reclassified. In patients with HF with reduced ejection fraction with preserved tricuspid annular plane systolic excursion, RV free-wall strain provides incremental prognostic information and improved risk stratification. © 2018 American Heart Association, Inc.

Effects of Pedal Speed and Crank Length on Pedaling Mechanics during Submaximal Cycling.

PubMed

Barratt, Paul Richard; Martin, James C; Elmer, Steve J; Korff, Thomas

2016-04-01

During submaximal cycling, the neuromuscular system has the freedom to select different intermuscular coordination strategies. From both a basic science and an applied perspective, it is important to understand how the central nervous system adjusts pedaling mechanics in response to changes in pedaling conditions. To determine the effect of changes in pedal speed (a marker of muscle shortening velocity) and crank length (a marker of muscle length) on pedaling mechanics during submaximal cycling. Fifteen trained cyclists performed submaximal isokinetic cycling trials (90 rpm, 240 W) using pedal speeds of 1.41 to 1.61 m·s(-1) and crank lengths of 150 to 190 mm. Joint powers were calculated using inverse dynamics. Increases in pedal speed and crank length caused large increases knee and hip angular excursions and velocities (P < 0.05), whereas ankle angular kinematics stayed relatively constant (P > 0.05). Joint moments and joint powers were less affected by changes in the independent variables, but some interesting effects and trends were observed. Most noteworthy, knee extension moments and powers tended to decrease, whereas hip extension power tended to increase with an increase in crank length. The distribution of joint moments and powers is largely maintained across a range of pedaling conditions. The crank length induced differences in knee extension moments, and powers may represent a trade-off between the central nervous system's attempts to simultaneously minimize muscle metabolic and mechanical stresses. These results increase our understanding of the neural and mechanical mechanisms underlying multi-joint task performance, and they have practical relevance to coaches, athletes, and clinicians.

The Precambrian Biogeochemical Carbon Isotopic Record: Contributions of Thermal Versus Biological Processes

NASA Technical Reports Server (NTRS)

DesMarais, David J.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

Superplumes offer a new approach for understanding global C cycles. Isotopes help to discern the impacts of geological, environmental and biological processes ujpun the evolution of these cycles. For example, C-13/C-12 values of coeval sedimentary organics and carbonates give global estimates of the fraction of C buried as organics (Forg), which today lies near 0.2. Before Oxygenic photosynthesis arose, our biosphere obtained reducing power for biosynthesis solely from thermal volatiles and rock alteration. Thus Forg was dominated by the mantle redox state, which has remained remarkably constant for greater than Gy. Recent data confirm that the long-term change in Forg had been small, indicating that the mantle redox buffer remains important even today. Oxygenic photosynthesis enabled life to obtain additional reducing power by splitting the water molecule. Accordingly, biological organic production rose above the level constrained by the mantle-derived flux of reduced species. For example, today, chemoautotrophs harvesting energy from hydrothermal emanations can synthesize at most between 0.2 x 10(exp 12) and 2x 10(exp 12) mol C yr-1 of organic C globally. In contrast, global photosynthetic productivity is estimated at 9000 x 10(exp 12) mol C yr-1. Occasionally photosynthetic productivity did contribute to dramatically -elevated Forg values (to 0.4 or more) as evidenced by very high carbonate C-13/C-12. The interplay between biological, tectonic and other environmental factors is illustrated by the mid-Archean to mid-Proterozoic isotopic record. The relatively constant C-13/C-12 values of Archean carbonates support the view that photosynthetically-driven Forg increases were not yet possible. In contrast, major excursions in C-13/C-12, and thus also in Forg, during the early Proterozoic confirmed the global importance of oxygenic photosynthesis by that time. Remarkably, the superplume event at 1.9 Ga did not trigger another major Forg increase, despite the favorable conditions for organic burial that were evidenced by elevated sea levels and higher black shale abundances. Perhaps those superplume-rated processes that favored enhanced organic burial were offset by the ability of mantle-derived redox buffering, which was enhanced during the superplume event, to limit excursions in Forg.

Project ECHO: Electronic Communications from Halo Orbit

NASA Technical Reports Server (NTRS)

Borrelli, Jason; Cooley, Bryan; Debole, Marcy; Hrivnak, Lance; Nielsen, Kenneth; Sangmeister, Gary; Wolfe, Matthew

1994-01-01

The design of a communications relay to provide constant access between the Earth and the far side of the Moon is presented. Placement of the relay in a halo orbit about the L2 Earth-Moon Lagrange point allows the satellite to maintain constant simultaneous communication between Earth and scientific payloads on the far side of the Moon. The requirements of NASA's Discovery-class missions adopted and modified for this design are: total project cost should not exceed $150 million excluding launch costs, launch must be provided by Delta-class vehicle, and the satellite should maintain an operational lifetime of 10 to 15 years. The spacecraft will follow a transfer trajectory to the L2 point, after launch by a Delta II 7925 vehicle in 1999. Low-level thrust is used for injection into a stationkeeping-free halo orbit once the spacecraft reaches the L2 point. The shape of this halo orbit is highly elliptical with the maximum excursion from the L2 point being 35000 km. A spun section and despun section connected through a bearing and power transfer assembly (BAPTA) compose the structure of the spacecraft. Communications equipment is placed on the despun section to provide for a stationary dual parabolic offset-feed array antenna system. The dual system is necessary to provide communications coverage during portions of maximum excursion on the halo orbit. Transmissions to the NASA Deep Space Network 34 m antenna include six channels (color video, two voice, scientific data from lunar payloads, satellite housekeeping and telemetry and uplinked commands) using the S- and X-bands. Four radioisotope thermoelectric generators (RTG's) provide a total of 1360 W to power onboard systems and any two of the four Hughes 13 cm ion thrusters at once. Output of the ion thrusters is approximately 17.8 mN each with xenon as the propellant. Presence of torques generated by solar pressure on the antenna dish require the addition of a 'skirt' extending from the spun section of the satellite for balance. Total mass of the satellite is approximately 900 kg at a cost of $130 million FY99.

Is most of the Tommotian missing in the White-Inyo region eastern California

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

Corsetti, F.A.

Integration of carbon-isotope chemostratigraphic data with trace fossil assemblages suggests that a significant hiatus may be present within the Lower Member of the Deep Spring Formation, potentially impacting the placement of the Neoproterozoic-Cambrian boundary in eastern California and western Nevada. A positive carbon-isotopic excursion of 4% PDB is present in the lowermost Lower Deep Spring, and is associated with Zone 1 trace fossils (latest Vendian) and small shelly fossils of disputed age (latest Proterozoic or Tommotian). A negative isotopic excursion is observed throughout the remaining Deep Spring Formation, and is associated with Zone 3 trace fossils (latest Tommotian-Atdabanian in age).more » The positive excursion in the lowermost Deep Spring is tentatively correlated with the pronounced isotopic maximum in the latest Vendian (possibly Nemakit-Daldyn) of the Siberian Platform (cycle 1 of Kirshvink et al., 1991). The negative excursion is correlated with a similar trend in the latest Tommotian-Atdabanian of the Siberian Platform (cycle 4 of Kirshvink et al., 1991). Thus, a hiatus, potentially encompassing most of the Tommotian, is postulated to be present within the Lower Member of the Deep Spring Formation. Although the fossil and isotopic data are consistent with the presence of a break in the section, sedimentological field evidence for the hiatus is somewhat cryptic. The recognition of this hiatus may impact the global significance of the presumed Tommotian small shelly fossils of the White-Inyo region, as well as the placement of the Neoproterozoic-Cambrian boundary in this sequence.« less

Modelling tendon excursions and moment arms of the finger flexors: anatomic fidelity versus function.

PubMed

Kociolek, Aaron M; Keir, Peter J

2011-07-07

A detailed musculoskeletal model of the human hand is needed to investigate the pathomechanics of tendon disorders and carpal tunnel syndrome. The purpose of this study was to develop a biomechanical model with realistic flexor tendon excursions and moment arms. An existing upper extremity model served as a starting point, which included programmed movement of the index finger. Movement capabilities were added for the other fingers. Metacarpophalangeal articulations were modelled as universal joints to simulate flexion/extension and abduction/adduction while interphalangeal articulations used hinges to represent flexion. Flexor tendon paths were modelled using two approaches. The first method constrained tendons with control points, representing annular pulleys. The second technique used wrap objects at the joints as tendon constraints. Both control point and joint wrap models were iteratively adjusted to coincide with tendon excursions and moment arms from a anthropometric regression model using inputs for a 50th percentile male. Tendon excursions from the joint wrap method best matched the regression model even though anatomic features of the tendon paths were not preserved (absolute differences: mean<0.33 mm, peak<0.74 mm). The joint wrap model also produced similar moment arms to the regression (absolute differences: mean<0.63 mm, peak<1.58 mm). When a scaling algorithm was used to test anthropometrics, the scaled joint wrap models better matched the regression than the scaled control point models. Detailed patient-specific anatomical data will improve model outcomes for clinical use; however, population studies may benefit from simplified geometry, especially with anthropometric scaling. Copyright © 2011 Elsevier Ltd. All rights reserved.

Evaluation of diaphragmatic motion in normal and diaphragmatic paralyzed dogs using M-mode ultrasonography.

PubMed

Choi, Mihyun; Lee, Namsoon; Kim, Ahyoung; Keh, Seoyeon; Lee, Jinsoo; Kim, Hyunwook; Choi, Mincheol

2014-01-01

Diagnosis of unilateral diaphragmatic paralysis in dogs is currently based on fluoroscopic detection of unequal movement between the crura. Bilateral paralysis may be more difficult to confirm with fluoroscopy because diaphragmatic movement is sometimes produced by compensatory abdominal muscle contractions. The purpose of this study was to develop a new method to evaluate diaphragmatic movement using M-mode ultrasonography and to describe findings for normal and diaphragmatic paralyzed dogs. Fifty-five clinically normal dogs and two dogs with diaphragmatic paralysis were recruited. Thoracic radiographs were acquired for all dogs and fluoroscopy studies were also acquired for clinically affected dogs. Two observers independently measured diaphragmatic direction of motion and amplitude of excursion using M-mode ultrasonography for dogs meeting study inclusion criteria. Eight of the clinically normal dogs were excluded due to abnormal thoracic radiographic findings. For the remaining normal dogs, the lower limit values of diaphragmatic excursion were 2.85-2.98 mm during normal breathing. One dog with bilateral diaphragmatic paralysis showed paradoxical movement of both crura at the end of inspiration. One dog with unilateral diaphragmatic paralysis had diaphragmatic excursion values of 2.00 ± 0.42 mm on the left side and 4.05 ± 1.48 mm on the right side. The difference between left and right diaphragmatic excursion values was 55%. Findings indicated that M-mode ultrasonography is a relatively simple and objective method for measuring diaphragmatic movement in dogs. Future studies are needed in a larger number of dogs with diaphragmatic paralysis to determine the diagnostic sensitivity of this promising new technique. © 2013 American College of Veterinary Radiology.

Forefoot-rearfoot coupling patterns and tibial internal rotation during stance phase of barefoot versus shod running.

PubMed

Eslami, Mansour; Begon, Mickaël; Farahpour, Nader; Allard, Paul

2007-01-01

Based on twisted plate and mitered hinge models of the foot and ankle, forefoot-rearfoot coupling motion patterns can contribute to the amount of tibial rotation. The present study determined the differences of forefoot-rearfoot coupling patterns as well as excessive excursion of tibial internal rotation in shod versus barefoot conditions during running. Sixteen male subjects ran 10 times at 170 steps per minute under the barefoot and shod conditions. Forefoot-rearfoot coupling motions were assessed by measuring mean relative phase angle during five intervals of stance phase for the main effect of five time intervals and two conditions (ANOVA, P<0.05). Tibial internal rotation excursion was compared between the shod and barefoot conditions over the first 50% of stance phase using paired t-test, (P<0.05). Forefoot adduction/abduction and rearfoot eversion/inversion coupling motion patterns were significantly different between the conditions and among the intervals (P<0.05; effect size=0.47). The mean absolute relative angle was significantly modified to 37 degrees in-phase relationship at the heel-strike of running with shoe wears. No significant differences were noted in the tibial internal rotation excursion between shod and barefoot conditions. Significant variations in the forefoot adduction/abduction and rearfoot eversion/inversion coupling patterns could have little effect on the amount of tibial internal rotation excursion. Yet it remains to be determined whether changes in the frontal plane forefoot-rearfoot coupling patterns influence the tibia kinematics for different shoe wears or foot orthotic interventions. The findings question the rational for the prophylactic use of forefoot posting in foot orthoses.

National facilities study. Volume 3: Mission and requirements model report

NASA Technical Reports Server (NTRS)

1994-01-01

The National Facility Study (NFS) was initiated in 1992 by Daniel S. Goldin, Administrator of NASA as an initiative to develop a comprehensive and integrated long-term plan for future facilities. The resulting, multi-agency NFS consisted of three Task Groups: Aeronautics, Space Operations, and Space Research and Development (R&D) Task Groups. A fourth group, the Engineering and Cost Analysis Task Group, was subsequently added to provide cross-cutting functions, such as assuring consistency in developing an inventory of space facilities. Space facilities decisions require an assessment of current and future needs. Therefore, the two task groups dealing with space developed a consistent model of future space mission programs, operations and R&D. The model is a middle ground baseline constructed for NFS analytical purposes with excursions to cover potential space program strategies. The model includes three major sectors: DOD, civilian government, and commercial space. The model spans the next 30 years because of the long lead times associated with facilities development and usage. This document, Volume 3 of the final NFS report, is organized along the following lines: Executive Summary -- provides a summary view of the 30-year mission forecast and requirements baseline, an overview of excursions from that baseline that were studied, and organization of the report; Introduction -- provides discussions of the methodology used in this analysis; Baseline Model -- provides the mission and requirements model baseline developed for Space Operations and Space R&D analyses; Excursions from the baseline -- reviews the details of variations or 'excursions' that were developed to test the future program projections captured in the baseline; and a Glossary of Acronyms.

Taking the pulse of the carbon release during the onset of the Paleocene-Eocene thermal maximum

NASA Astrophysics Data System (ADS)

Babila, T. L.; Bralower, T. J.; Robinson, M. M.; Self-Trail, J. M.; Zachos, J. C.

2015-12-01

The Paleocene-Eocene thermal maximum (PETM) (~55 Ma) is a warming event characterized by a negative carbon isotope excursion (CIE) representing a large and rapid injection of carbon into global reservoirs. Debate continues regarding the mechanism, magnitude, and tempo of the carbon released. A few terrestrial and marine sediment records document two distinct δ13C excursions a pre-onset excursion (POE) and CIE interpreted as evidence of multiple carbon injections. We generated geochemical records of ocean carbonate chemistry and temperature using cores drilled by the U.S Geological Survey (USGS) that recovered expanded sections of the PETM onset along the mid-Atlantic coastal plain. Our stable isotope (δ13C and δ18O) planktonic foraminifer records from South Dover Bridge (SDB), Maryland USA exhibit prominent anomalies across the Paleocene-Eocene boundary consistent to proximal coastal sites. δ13C records of mixed-layer (Acarinina spp.) and thermocline (Subbotina spp.) dwelling planktonic foraminifera show two negative carbon excursions that include a 2 ‰ POE and 3-4 ‰ CIE that return to baseline values between events in conjunction with bulk carbonate trends. Remarkably, contemporaneous foraminifer δ18O records exhibit only a minor response during the POE. This could be an artifact of preservation, or at face value, indicative of little to no warming. For the latter, this would require a rapid, but relatively small carbon release. To test the coupled link between atmosphere and surface ocean δ13C records we aim to integrate our geochemical results with model simulations to establish the duration and global extent of multiple carbon releases.

The Effect of Pilates Exercise on Trunk and Postural Stability and Throwing Velocity in College Baseball Pitchers: Single Subject Design

PubMed Central

Howe, Katherine

2007-01-01

Background Baseball pitchers need trunk strength to maximize performance. The Pilates method of exercise is gaining popularity throughout the country as a fitness and rehabilitation method of exercise. However, very few studies exist that examine the effects of the Pilates method of exercise on trunk strength or performance. Objectives Using a single subject, multiple baseline across subjects design, this study examines the effects of the Pilates method of exercise on performance of double leg lowering, star excursion balance test, and throwing velocity in college-aged baseball pitchers. Methods A convenience sample of three college baseball pitchers served as the subjects for this single subject design study. For each subject, double leg lowering, star excursion balance test, and throwing speed were measured prior to the introduction of the intervention. When baseline test values showed consistent performance, the intervention was introduced to one subject at a time. Intervention was introduced to the other subjects over a period of 4 weeks as they also demonstrated consistent performance on the baseline tests. Intervention was continued with periodic tests for the remainder of the 10 week trial. Results Each subject improved in performance on double leg lowering (increased 24.43-32.7%) and star excursion balance test (increased 4.63-17.84%) after introduction of the intervention. Throwing speed improved in two of the three subjects (up to 5.61%). Discussion and Conclusions The Pilates method of exercise may contribute to improved performance in double leg lowering, star excursion balance tests, and throwing speed in college baseball pitchers. PMID:21522199

The impact of round window vs cochleostomy surgical approaches on interscalar excursions in the cochlea: Preliminary results from a flat-panel computed tomography study.

PubMed

Jiam, Nicole T; Limb, Charles J

2016-09-01

To evaluate incidence of interscalar excursions between round window (RW) and cochleostomy approaches for cochlear implant (CI) insertion. This was a retrospective case-comparison. Flat-panel CT (FPCT) scans for 8 CI users with Med-El standard length electrode arrays were collected. Surgical technique was identified by a combination of operative notes and FPCT imaging. Four cochleae underwent round window insertion and 4 cochleae underwent cochleostomy approaches anterior and inferior to the round window. In our pilot study, cochleostomy approaches were associated with a higher likelihood of interscalar excursion. Within the cochleostomy group, we found 29% of electrode contacts (14 of 48 electrodes) to be outside the scala tympani. On the other hand, 8.5% of the electrode contacts (4 of 47 electrodes) in the round window insertion group were extra-scalar to the scala tympani. These displacements occurred at a mean angle of occurrence of 364° ± 133°, near the apex of the cochlea. Round window electrode displacements tend to localize at angle of occurrences of 400° or greater. Cochleostomy electrodes occurred at an angle of occurrence of 19°-490°. Currently, the optimal surgical approach for standard CI electrode insertion is highly debated, to a certain extent due to a lack of post-operative assessment of intracochlear electrode contact. Based on our preliminary findings, cochleostomy approach is associated with an increased likelihood of interscalar excursions, and these findings should be further evaluated with future prospective studies.

Measurements of Eustachian tube dilation by video endoscopy.

PubMed

Poe, Dennis S; Pyykkö, Ilmari

2011-07-01

1. To create techniques for measurement of parameters of Eustachian tube (ET) dilation as observed with video endoscopy. 2. To study correlations of the parameters between healthy subjects and patients with ET dysfunction to determine if they may be important for clinical or investigational use. Prospective study in an academic center. 3 groups of adults: healthy subjects, otitis media with effusion (OME), patulous ET. Video software analyses were performed on video recordings from subjects' transnasal endoscopy to measure parameters of the tubal dilation cycle. 24 ETs of 15 healthy subjects, 24 ETs of 15 patulous ET and 20 ETs of 13 OME patients. Mean values for healthy subjects: cycle time 995 ms (SD 404.7), valve opening time 10.5 ms (SD 6.34), torus rotation time 176 ms (SD 151.5 and angle of torus rotation 34.2° (SD 14.3). Palatal elevation, measured as a percentage of torus height was 34.8% (SD 16.6) and excursion of the antero-lateral wall 35.5 % (SD 16.3). Lateral excursion of the antero-lateral wall was significantly less in patulous ET (18.7%, SD 15.1, p = 0.001) and in dilatory dysfunction (23.9%, SD 21.7, p = 0.048). The other parameters were not statistically different between healthy subjects and patients. Lateral excursion of the ET's antero-lateral wall was significantly reduced in OME and patulous ET patients compared with healthy subjects. Evaluation of the excursion of the lateral wall of the ET, which is due to TVP muscle action, may be an important parameter for further clinical and research study.

Sedimentary evidence for enhanced hydrological cycling in response to rapid carbon release during the early Toarcian oceanic anoxic event

NASA Astrophysics Data System (ADS)

Izumi, Kentaro; Kemp, David B.; Itamiya, Shoma; Inui, Mutsuko

2018-01-01

A pronounced excursion in the carbon-isotope composition of biospheric carbon and coeval seawater warming during the early Toarcian (∼183 Ma) has been linked to the large-scale transfer of 12C-enriched carbon to the oceans and atmosphere. A European bias in the distribution of available data means that the precise pattern, tempo and global expression of this carbon cycle perturbation, and the associated environmental responses, remain uncertain. Here, we present a new cm-scale terrestrial-dominated carbon-isotope record through an expanded lower Toarcian section from Japan that displays a negative excursion pattern similar to marine and terrestrial carbon-isotope records documented from Europe. These new data suggest that 12C-enriched carbon was added to the biosphere in at least one rapid, millennial-scale pulse. Sedimentological analysis indicates a close association between the carbon-isotope excursion and high-energy sediment transport and enhanced fluvial discharge. Together, these data support the hypothesis that a sudden strengthening of the global hydrological cycle occurred in direct and immediate response to rapid carbon release and atmospheric warming.

Fatigue-induced changes in decline running.

PubMed

Mizrahi, J; Verbitsky, O; Isakov, E

2001-03-01

Study the relation between muscle fatigue during eccentric muscle contractions and kinematics of the legs in downhill running. Decline running on a treadmill was used to acquire data on shock accelerations, muscle activity and kinematics, for comparison with level running. In downhill running, local muscle fatigue is the cause of morphological muscle damage which leads to reduced attenuation of shock accelerations. Fourteen subjects ran on a treadmill above level-running anaerobic threshold speed for 30 min, in level and -4 degrees decline running. The following were monitored: metabolic fatigue by means of respiratory parameters; muscle fatigue of the quadriceps by means of elevation in myoelectric activity; and kinematic parameters including knee and ankle angles and hip vertical excursion by means of computerized videography. Data on shock transmission reported in previous studies were also used. Quadriceps fatigue develops in parallel to an increasing vertical excursion of the hip in the stance phase of running, enabled by larger dorsi flexion of the ankle rather than by increased flexion of the knee. The decrease in shock attenuation can be attributed to quadriceps muscle fatigue in parallel to increased vertical excursion of the hips.

Physiological asymmetry of trunk ranging and pelvis motility: an anatomo-functional study in 80 healthy subjects.

PubMed

Macchi, Claudio; Biricolti, Claudia; Cappelli, Lorenza; Galli, Francesca; Molino-Lova, Raffaele; Cecchi, Francesca; Corigliano, Alvaro; Miniati, Benedetta; Conti, Andrea A; Gulisano, Massimo; Catini, Claudio; Gensini, Gian Franco

2002-01-01

A key feature in physiotherapeutic treatment of patients with motion disturbances is the appropriate ranging of the trunk and pelvis motility. Eighty subjects randomly selected and free from known pathology of the muscular-skeletal and/or of the neurological system classed into four groups according to the age and the sex have been assessed, by using a new, simple and easy administrable tool. Our results demonstrate that the new measurement tool showed a very low intra- and inter-observer variability, that healthy subjects showed a more adduced and elevated right scapula if compared to the contralateral one and, as regard as the pelvic motion, a broader joint excursion in passive motion compared with active motion in the overall group, a broader joint excursion in young subjects compared with elderly ones, and a broader joint excursion in female subjects compared with males subjects. In conclusion our study allowed to identify a range of physiological asymmetry and pelvis motility. Such a range of physiological asymmetry might be useful as a reference for the physiotherapists.

Mercury enrichment indicates volcanic triggering of Valanginian environmental change

NASA Astrophysics Data System (ADS)

Charbonnier, Guillaume; Morales, Chloé; Duchamp-Alphonse, Stéphanie; Westermann, Stéphane; Adatte, Thierry; Föllmi, Karl B.

2017-01-01

The Valanginian stage (Early Cretaceous) includes an episode of significant environmental changes, which are well defined by a positive δ13C excursion. This globally recorded excursion indicates important perturbations in the carbon cycle, which has tentatively been associated with a pulse in volcanic activity and the formation of the Paraná-Etendeka large igneous province (LIP). Uncertainties in existing age models preclude, however, its positive identification as a trigger of Valanginian environmental changes. Here we report that in Valanginian sediments recovered from a drill core in Wąwał (Polish Basin, Poland), and from outcrops in the Breggia Gorge (Lombardian Basin, southern Switzerland), and Orpierre and Angles (Vocontian Basin, SE France), intervals at or near the onset of the positive δ13C excursion are significantly enriched in mercury (Hg). The persistence of the Hg anomaly in Hg/TOC, Hg/phyllosilicate, and Hg/Fe ratios shows that organic-matter scavenging and/or adsorbtion onto clay minerals or hydrous iron oxides only played a limited role. Volcanic outgassing was most probably the primary source of the Hg enrichments, which demonstrate that an important magmatic pulse triggered the Valanginian environmental perturbations.

Predictable "individual differences" in uptake and excretion of gases and lipid soluble vapours simulation study.

PubMed Central

Fiserova-Bergerova, V; Vlach, J; Cassady, J C

1980-01-01

A five-compartment pharmacokinetic model with two excretory pathways, exhalation and metabolism, based on first order kinetics is used to outline the effect of body build, pulmonary ventilation, and lipid content in blood on uptake, distribution, and clearance of low solubility gases and lipid soluble vapours during and after exposure. The model shows the extent that individual differences have on altering uptake and distribution, with consequent changes in blood concentration, rate of excretion, and toxicity, even when variations in these parameters are within physiological ranges. The model is also used to describe the concentration variation of inhaled substances in tissues of subjects exposed to concentrations with permitted excursions. During the same course of exposure, the tissue concentrations of low solubility gases fluctuate much more than tissue concentrations of lipid soluble vapours. The fluctuation is reduced by metabolism of inhaled substance. These conclusions are recommended for consideration whenever evaluating the effect of excursions above the threshold limit values used in the control of industrial exposures (by excursion factors). PMID:7370192

Sea surface temperature anomalies driven by oceanic local forcing in the Brazil-Malvinas Confluence

NASA Astrophysics Data System (ADS)

da Silveira, Isabel Porto; Pezzi, Luciano Ponzi

2014-03-01

Sea surface temperature (SST) anomaly events in the Brazil-Malvinas Confluence (BMC) were investigated through wavelet analysis and numerical modeling. Wavelet analysis was applied to recognize the main spectral signals of SST anomaly events in the BMC and in the Drake Passage as a first attempt to link middle and high latitudes. The numerical modeling approach was used to clarify the local oceanic dynamics that drive these anomalies. Wavelet analysis pointed to the 8-12-year band as the most energetic band representing remote forcing between high to middle latitudes. Other frequencies observed in the BMC wavelet analysis indicate that part of its variability could also be forced by low-latitude events, such as El Niño. Numerical experiments carried out for the years of 1964 and 1992 (cold and warm El Niño-Southern Oscillation (ENSO) phases) revealed two distinct behaviors that produced negative and positive sea surface temperature anomalies on the BMC region. The first behavior is caused by northward cold flow, Río de la Plata runoff, and upwelling processes. The second behavior is driven by a southward excursion of the Brazil Current (BC) front, alterations in Río de la Plata discharge rates, and most likely by air-sea interactions. Both episodes are characterized by uncoupled behavior between the surface and deeper layers.

The point of entry contributes to the organization of exploratory behavior of rats on an open field: an example of spontaneous episodic memory.

PubMed

Nemati, Farshad; Whishaw, Ian Q

2007-08-22

The exploratory behavior of rats on an open field is organized in that animals spend disproportionate amounts of time at certain locations, termed home bases, which serve as centers for excursions. Although home bases are preferentially formed near distinctive cues, including visual cues, animals also visit and pause and move slowly, or linger, at many other locations in a test environment. In order to further examine the organization of exploratory behavior, the present study examined the influence of the point of entry on animals placed on an open field table that was illuminated either by room light or infrared light (a wavelength in which they cannot see) and near which, or on which, distinctive cues were placed. The main findings were that in both room light and infrared light tests, rats visited and lingered at the point of entry significantly more often than comparative control locations. Although the rats also visited and lingered in the vicinity of salient visual cues, the point of entry still remained a focus of visits. Finally, the preference for the point of entry increased as a function of salience of the cues marking that location. That the point of entry influences the organization of exploratory behavior is discussed in relation to the idea that the exploratory behavior of the rat is directed toward optimizing security as well as forming a spatial representation of the environment.

Electricity by intermittent sources: An analysis based on the German situation 2012

NASA Astrophysics Data System (ADS)

Wagner, Friedrich

2014-02-01

The 2012 data of the German load, the on- and offshore and the photo-voltaic energy production are used and scaled to the limit of supplying the annual demand (100% case). The reference mix of the renewable energy (RE) forms is selected such that the remaining back-up energy is minimised. For the 100% case, the RE power installation has to be about 3 times the present peak load. The back-up system can be reduced by 12% in this case. The surplus energy corresponds to 26% of the demand. The back-up system and more so the grid must be able to cope with large power excursions. All components of the electricity supply system operate at low capacity factors. Large-scale storage can hardly be motivated by the effort to further reduce CO2 emission. Demand-side management will intensify the present periods of high economic activities. Its rigorous implementation will expand the economic activities into the weekends. On the basis of a simple criterion, the increase of periods with negative electricity prices in Germany is assessed. It will be difficult with RE to meet the low CO2 emission factors which characterise those European Countries which produce electricity mostly by nuclear and hydro power.

Divertor power load feedback with nitrogen seeding in ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Kallenbach, A.; Dux, R.; Fuchs, J. C.; Fischer, R.; Geiger, B.; Giannone, L.; Herrmann, A.; Lunt, T.; Mertens, V.; McDermott, R.; Neu, R.; Pütterich, T.; Rathgeber, S.; Rohde, V.; Schmid, K.; Schweinzer, J.; Treutterer, W.; ASDEX Upgrade Team

2010-05-01

Feedback control of the divertor power load by means of nitrogen seeding has been developed into a routine operational tool in the all-tungsten clad ASDEX Upgrade tokamak. For heating powers above about 12 MW, its use has become inevitable to protect the divertor tungsten coating under boronized conditions. The use of nitrogen seeding is accompanied by improved energy confinement due to higher core plasma temperatures, which more than compensates the negative effect of plasma dilution by nitrogen on the neutron rate. This paper describes the technical details of the feedback controller. A simple model for its underlying physics allows the prediction of its behaviour and the optimization of the feedback gain coefficients used. Storage and release of nitrogen in tungsten surfaces were found to have substantial impact on the behaviour of the seeded plasma, resulting in increased nitrogen consumption with unloaded walls and a latency of nitrogen release over several discharges after its injection. Nitrogen is released from tungsten plasma facing components with moderate surface temperature in a sputtering-like process; therefore no uncontrolled excursions of the nitrogen wall release are observed. Overall, very stable operation of the high-Z tokamak is possible with nitrogen seeding, where core radiative losses are avoided due to its low atomic charge Z and a high ELM frequency is maintained.

Electrochemical behavior of lead alloys in sulfuric and phosphoric acid solutions

NASA Astrophysics Data System (ADS)

Paleska, I.; Pruszkowska-Drachal, R.; Kotowski, J.; Dziudzi, A.; Milewski, J. D.; Kopczyk, M.; Czerwiński, A.

The electrochemical behavior of lead, lead-antimony, and lead-calcium-aluminium-tin alloys has been studied in solutions containing various concentrations of sulfuric and phosphoric acids. The dependence of these electrode processes on some experimental conditions (mainly sweep rate and potential range) has been studied. The measurements were performed using a cyclic voltammetry technique. The study and the analysis of the morphology of alloys have been performed using a scanning electron microscope (SEM). Cyclic voltammograms of the lead-antimony alloy electrodes, similarly to pure lead electrode, also show the "anodic excursion" peak under some experimental conditions. Well defined current waves, corresponding to the oxidation and reduction processes of Sb, are observed, if the alloy surface is freshly abraded. The oxidation of antimony starts at potentials at which the formation of PbO takes place. The peak current of Sb oxidation reaction decreases during successive cycles, suggesting that Sb dissolves from the alloy surface during the first CV sweeps. Another explanation for this effect might be the formation of a PbSO 4 selective membrane.

Functional morphology and comparative anatomy of appendicular musculature in Cuban Anolis lizards with different locomotor habits.

PubMed

Anzai, Wataru; Omura, Ayano; Diaz, Antonio Cadiz; Kawata, Masakado; Endo, Hideki

2014-07-01

We examined the diversity of the musculoskeletal morphology in the limbs of Anolis lizards with different habitats and identified variations in functional and morphological adaptations to different ecologies or behaviors. Dissection and isolation of 40 muscles from the fore- and hindlimbs of five species of Anolis were performed, and the muscle mass and length of the moment arm were compared after body size effects were removed. Ecologically and behaviorally characteristic morphological differences were observed in several muscles. Well-developed hindlimb extensors were observed in ground-dwelling species, A. sagrei and A. bremeri, and were considered advantageous for running, whereas adept climber species possessed expanded femoral retractors for weight-bearing during climbing. Moreover, morphological variations were observed among arboreal species. Wider excursions of the forelimb joint characterized A. porcatus, presumably enabling branch-to-branch locomotion, while A. equestris and A. angusticeps possessed highly developed adductor muscles for grasping thick branches or twigs. These findings suggest divergent evolution of musculoskeletal characteristic in the limbs within the genus Anolis, with correlations observed among morphological traits, locomotor performance, and habitat uses.

Bithermal fatigue: A simplified alternative to thermomechanical fatigue

NASA Technical Reports Server (NTRS)

Verrilli, Michael J.

1988-01-01

A bithermal fatigue test technique was proposed as a simplified alternative to the thermomechanical fatigue test. Both the thermomechanical cycle and the bithermal technique can be used to study nonisothermal fatigue behavior. The difference between the two cycles is that in a conventional thermomechanical fatigue cycle the temperature is continuously varied concurrently with the applied mechanical strains, but in the bithermal fatigue cycle the specimen is held at zero load during the temperature excursions and all the loads are applied at the two extreme temperatures of the cycle. Experimentally, the bithermal fatigue test technique offers advantages such as ease in synchronizing the temperature and mechanical strain waveforms, in minimizing temperature gradients in the specimen gauge length, and in reducing and interpreting thermal fatigue such as the influence of alternate high and low temperatures on the cyclic stress-strain response characteristics, the effects of thermal state, and the possibility of introducing high- and low-temperature deformation mechanisms within the same cycle. The bithermal technique was used to study nonisothermal fatigue behavior of alloys such as single-crystal PWA 1480, single-crystal Rene N4, cast B1900+Hf, and wrought Haynes 188.

Effects of Amplitude Variations on Deformation and Damage Evolution in SnAgCu Solder in Isothermal Cycling

NASA Astrophysics Data System (ADS)

Wentlent, Luke; Alghoul, Thaer M.; Greene, Christopher M.; Borgesen, Peter

2018-02-01

Although apparently simpler than in thermal cycling, the behavior of SnAgCu (SAC) solder joints in cyclic bending or vibration is not currently well understood. The rate of damage has been shown to scale with the inelastic work per cycle, and excursions to higher amplitudes lead to an apparent softening, some of which remains so that damage accumulation is faster in subsequent cycling at lower amplitudes. This frequently leads to a dramatic breakdown of current damage accumulation rules. An empirical damage accumulation rule has been proposed to account for this, but any applicability to the extrapolation of accelerated test results to life under realistic long-term service conditions remains to be validated. This will require a better understanding of the underlying mechanisms. The present work provides experimental evidence to support recent suggestions that the observed behavior is a result of cycling-induced dislocation structures providing for increased diffusion creep. It is argued that this means that the measured work is an indicator of the instantaneous dislocation density, rather than necessarily reflecting the actual work involved in the creation of the damage.

Using LSTMs to learn physiological models of blood glucose behavior.

PubMed

Mirshekarian, Sadegh; Bunescu, Razvan; Marling, Cindy; Schwartz, Frank

2017-07-01

For people with type 1 diabetes, good blood glucose control is essential to keeping serious disease complications at bay. This entails carefully monitoring blood glucose levels and taking corrective steps whenever they are too high or too low. If blood glucose levels could be accurately predicted, patients could take proactive steps to prevent blood glucose excursions from occurring. However, accurate predictions require complex physiological models of blood glucose behavior. Factors such as insulin boluses, carbohydrate intake, and exercise influence blood glucose in ways that are difficult to capture through manually engineered equations. In this paper, we describe a recursive neural network (RNN) approach that uses long short-term memory (LSTM) units to learn a physiological model of blood glucose. When trained on raw data from real patients, the LSTM networks (LSTMs) obtain results that are competitive with a previous state-of-the-art model based on manually engineered physiological equations. The RNN approach can incorporate arbitrary physiological parameters without the need for sophisticated manual engineering, thus holding the promise of further improvements in prediction accuracy.

Lake sedimentological and plant ecological development across the Early Danian hyperthermal, Boltysh Impact Crater, Ukraine

NASA Astrophysics Data System (ADS)

Ebinghaus, Alena; Jolley, David; Andrews, Steven; Kemp, David

2017-04-01

Past hyperthermals and associated negative carbon isotope excursions (CIEs) are inferred to have had significant impact on marine environments; however the formation and changes of terrestrial ecosystems across hyperthermals are less well constrained due to the lack of complete and high-resolution data. The Boltysh impact crater, Ukraine, which formed at the Cretaceous/Palaeogene (K/Pg) boundary at the northern margin of the Tethys Ocean, contains a >400 m thick unique and detailed lacustrine rock record of the Early Danian Dan-C2 hyperthermal. Based on a borehole (hole 42/11) drilled in the central part of the crater, we use a combination of sedimentological, palynological and carbon isotope data to 1) characterise and reconstruct lake formation and associated plant ecosystems, and 2) to assess lake sedimentological and ecological response to climatic variabilities during warming. Based on detailed facies analysis, 3 major gradual stages of lake formation are identified, indicating a strong relationship to carbon isotope shifts and associated climatic trends. Initial pre-excursion sedimentation was controlled by crater morphology and crater rim erosion transporting high amount of sediment into a shallow fresh water lake. During the negative excursion, sediment supply was increasingly characterised by inflow-evaporation ratio variabilities which affected seasonal stratification patterns and longer-term lake levels. An inferred increase in atmospheric pCO2 during the CIE, together with increasing mean annual temperatures, was likely responsible for periodic increases in bioproductivity. Palynological analyses demonstrate a gradual shift from mesic humid dominated vegetation to winterwet savannah-type vegetation at this stage, associated with an increase in mean annual temperatures and decrease in moisture availability. The positive excursion (recovery) and post-excursion stage is characterised by increased abundance of temperate mesic humid taxa. This cooling trend is associated with a gradual increase in sediment supply and return to fresh water conditions, reflecting increased drainage of the crater environment following the hyperthermal. Subordinate 21ky precession-paced moisture availability oscillations (MAOs) associated with rapid regime shifts from wet mesic humid to drier savannah biomes correspond to fluctuations in lake facies and lake levels during the negative excursion and suggest that a combination of climate and vegetation cover largely controlled clastic sediment supply at this stage. Smaller scaled regular variations in lamination style during each wet phase of the MAOs suggest a sub-orbital variability in weather conditions, sediment supply and lake stratification on probably annual to subannual scale and further implies changing magnitudes in seasonality. Gradual facies changes prior to CIE inception together with lamination variability suggests that the Dan-C2 event did not initiate large-scale sedimentological changes, but amplified and promoted sedimentary response to orbital controlled climate change.

Experimental Investigations in a Reactor Cavity Cooling System with Advanced Instrumentation for the Study of Instabilities, Oscillations, and Transients

NASA Astrophysics Data System (ADS)

Tompkins, Casey A.

A research team at University of Wisconsin - Madison designed and constructed a 1/4 height scaled experimental facility to study two-phase natural circulation cooling in a water-based reactor cavity cooling system (WRCCS) for decay heat removal in an advanced high temperature reactor. The facility is capable of natural circulation operation scaled for simulated decay heat removal (up to 28.5 kW m-2 (45 kW) input power, which is equivalent to 14.25 kW m-2 (6.8 MW) at full scale) and pressurized up to 2 bar. The UW-WRCCS facility has been used to study instabilities and oscillations observed during natural circulation flow due to evaporation of the water inventory. During two-phase operation, the system exhibits flow oscillations and excursions, which cause thermal oscillations in the structure. This can cause degradation in the mechanical structure at welds and limit heat transfer to the coolant. The facility is equipped with wire mesh sensors (WMS) that enable high-resolution measurements of the void fraction and steam velocities in order to study the instability's and oscillation's growth and decay during transient operation. Multiple perturbations to the system's operating point in pressure and inlet throttling have shown that the oscillatory behavior present under normal two-phase operating conditions can be damped and removed. Furthermore, with steady-state modeling it was discovered that a flow regime transition instability is the primary cause of oscillations in the UW-WRCCS facility under unperturbed conditions and that proper orifice selection can move the system into a stable operating regime.

ISRU Reactant, Fuel Cell Based Power Plant for Robotic and Human Mobile Exploration Applications

NASA Technical Reports Server (NTRS)

Baird, Russell S.; Sanders, Gerald; Simon, Thomas; McCurdy, Kerri

2003-01-01

Three basic power generation system concepts are generally considered for lander, rover, and Extra-Vehicular Activity (EVA) assistant applications for robotic and human Moon and Mars exploration missions. The most common power system considered is the solar array and battery system. While relatively simple and successful, solar array/battery systems have some serious limitations for mobile applications. For typical rover applications, these limitations include relatively low total energy storage capabilities, daylight only operating times (6 to 8 hours on Mars), relatively short operating lives depending on the operating environment, and rover/lander size and surface use constraints. Radioisotope power systems are being reconsidered for long-range science missions. Unfortunately, the high cost, political controversy, and launch difficulties that are associated with nuclear-based power systems suggests that the use of radioisotope powered landers, rovers, and EVA assistants will be limited. The third power system concept now being considered are fuel cell based systems. Fuel cell power systems overcome many of the performance and surface exploration limitations of solar array/battery power systems and the prohibitive cost and other difficulties associated with nuclear power systems for mobile applications. In an effort to better understand the capabilities and limitations of fuel cell power systems for Moon and Mars exploration applications, NASA is investigating the use of in-Situ Resource Utilization (ISRU) produced reactant, fuel cell based power plants to power robotic outpost rovers, science equipment, and future human spacecraft, surface-excursion rovers, and EVA assistant rovers. This paper will briefly compare the capabilities and limitations of fuel cell power systems relative to solar array/battery and nuclear systems, discuss the unique and enhanced missions that fuel cell power systems enable, and discuss the common technology and system attributes possible for robotic and human exploration to maximize scientific return and minimize cost and risk to both. Progress made to date at the Johnson Space Center on an ISRU producible reactant, Proton Exchange Membrane (PEM) fuel cell based power plant project to demonstrate the concept in conjunction with rover applications will be presented in detail.

ISRU Reactant, Fuel Cell Based Power Plant for Robotic and Human Mobile Exploration Applications

NASA Astrophysics Data System (ADS)

Baird, Russell S.; Sanders, Gerald; Simon, Thomas; McCurdy, Kerri

2003-01-01

Three basic power generation system concepts are generally considered for lander, rover, and Extra-Vehicular Activity (EVA) assistant applications for robotic and human Moon and Mars exploration missions. The most common power system considered is the solar array and battery system. While relatively simple and successful, solar array/battery systems have some serious limitations for mobile applications. For typical rover applications, these limitations include relatively low total energy storage capabilities, daylight only operating times (6 to 8 hours on Mars), relatively short operating lives depending on the operating environment, and rover/lander size and surface use constraints. Radioisotope power systems are being reconsidered for long-range science missions. Unfortunately, the high cost, political controversy, and launch difficulties that are associated with nuclear-based power systems suggests that the use of radioisotope powered landers, rovers, and EVA assistants will be limited. The third power system concept now being considered are fuel cell based systems. Fuel cell power systems overcome many of the performance and surface exploration limitations of solar array/battery power systems and the prohibitive cost and other difficulties associated with nuclear power systems for mobile applications. In an effort to better understand the capabilities and limitations of fuel cell power systems for Moon and Mars exploration applications. NASA is investigating the use of In-Situ Resource Utilization (ISRU) produced reactant, fuel cell based power plants to power robotic outpost rovers, science equipment, and future human spacecraft, surface-excursion rovers, and EVA assistant rovers. This paper will briefly compare the capabilities and limitations of fuel cell power systems relative to solar array/battery and nuclear systems, discuss the unique and enhanced missions that fuel cell power systems enable, and discuss the common technology and system attributes possible for robotic and human exploration to maximize scientific return and minimize cost and risk to both. Progress made to date at the Johnson Space Center on an ISRU producible reactant. Proton Exchange Membrane (PEM) fuel cell based power plant project for use in the first demonstration of this concept in conjunction with rover applications will be presented in detail.

Consistency of a lumbar movement pattern across functional activities in people with low back pain.

PubMed

Marich, Andrej V; Hwang, Ching-Ting; Salsich, Gretchen B; Lang, Catherine E; Van Dillen, Linda R

2017-05-01

Limitation in function is a primary reason people with low back pain seek medical treatment. Specific lumbar movement patterns, repeated throughout the day, have been proposed to contribute to the development and course of low back pain. Varying the demands of a functional activity test may provide some insight into whether people display consistent lumbar movement patterns during functional activities. Our purpose was to examine the consistency of the lumbar movement pattern during variations of a functional activity test in people with low back pain and back-healthy people. 16 back-healthy adults and 32 people with low back pain participated. Low back pain participants were classified based on the level of self-reported functional limitations. Participants performed 5 different conditions of a functional activity test. Lumbar excursion in the early phase of movement was examined. The association between functional limitations and early phase lumbar excursion for each test condition was examined. People with low back pain and high levels of functional limitation demonstrated a consistent pattern of greater early phase lumbar excursion across test conditions (p<0.05). For each test condition, the amount of early phase lumbar excursion was associated with functional limitation (r=0.28-0.62). Our research provides preliminary evidence that people with low back pain adopt consistent movement patterns during the performance of functional activities. Our findings indicate that the lumbar spine consistently moves more readily into its available range in people with low back pain and high levels of functional limitation. How the lumbar spine moves during a functional activity may contribute to functional limitations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemostratigraphy of the Gohan Formation in the eastern central Korea : implications for the Capitanian environmental change

NASA Astrophysics Data System (ADS)

Kwon, Hyosang; Lee, Yong Il; Lim, Hyoun Soo

2017-04-01

The Gohan Formation in the Pyeongan Supergroup in central eastern Korea was deposited in a marginal marine to terrestrial setting in the Capitanian. It is 450 m thick and comprises alternation of gray-greenish medium-grained sandstone and mudrock. A detailed carbon isotope profile along with some paleoenvironmental proxies are presented for the Gohan Formation at Danyang site. CN ratios of organic matters reveal the presence of both vascular and non vascular plants. Excursion of carbon isotope ratios represents disturbance of carbon cycle. Carbon isotope values indicated a 3‰ negative excursion in the lower part of the studied section. This can be interpreted carbon cycle disturbance from the Capitanian extinction event. Mercury concentration is a proxy of volcanic activity. The horizon of a mercury peak near the bottom of the section is consistent with that of negative carbon isotope excursion and the coincidence between negative carbon isotope excursion and high mercury concentration may represent the influence from Emeishan volcanism, which has been regarded as a possible cause of the Capitanian extiction. Two more mercury peaks are noted in the upper part of the section but they are not related to carbon cycle disturbance which suggests effect of local volcanic eruptions as supported by the presence of volcanic rock fragments in coarse-grained sediment. Trace metal redox proxies indicate that the depositional basin was ventillated. TOC values tend to increase when the concentration of redox elements rise. However, the TOC and trace metal redox proxies trends are observed to behave independently of changes in carbon isotope and mercury concentrations suggesting transitions in local paleoenvironmental conditions.

Variability in mid-depth ventilation of the western Atlantic Ocean during the last deglaciation

NASA Astrophysics Data System (ADS)

Voigt, I.; Cruz, A. P. S.; Mulitza, S.; Chiessi, C. M.; Mackensen, A.; Lippold, J.; Antz, B.; Zabel, M.; Zhang, Y.; Barbosa, C. F.; Tisserand, A. A.

2017-09-01

Negative stable carbon isotopic excursions have been observed throughout most of the mid-depth ( 1000-3000 m) Atlantic Ocean during Heinrich Stadial 1 (HS1) and the Younger Dryas (YD). Although there is an agreement that these mid-depth excursions were in some way associated with a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), there is still no consensus on the precise mechanism(s). Here we present benthic stable carbon and oxygen isotopic (δ13C and δ18O) records from five cores from the western equatorial Atlantic (WEA). Together with published benthic isotopic records from nearby cores, we produced a WEA depth transect ( 800-2500 m). We compare HS1 and YD data from this transect with data from previously published North and South Atlantic cores and demonstrate that the largest negative δ13C excursions occurred in the WEA during these times. Moreover, our benthic δ18O records require the presence of two water masses flowing from the Southern Ocean, bisected by a Northern Component Water (NCW). Given that δ18O is a conservative water mass tracer, we suggest that δ13C was decoupled from water mass composition and does not correspond to simple alternations between northern and southern sourced waters. Instead, δ13C behaved non-conservatively during HS1 and the YD. Consistently with our new 231Pa/230Th record from the WEA transect, that allowed the reconstruction of AMOC strength, we hypothesize that the negative δ13C excursions reflect an increase in the residence time of NCW in response to a weakened AMOC, allowing for a marked accumulation of 13C-depleted respired carbon at the mid-depth WEA.

Evolution and Adaptation of Phytoplankton Photosynthetic Pathways to perturbations of the geological carbon system

NASA Astrophysics Data System (ADS)

Rickaby, R. E.; Young, J. N.; Hermoso, M.; Heureux, A.; McCLelland, H.; Lee, R.; Eason Hubbard, M.

2012-12-01

The ocean and atmosphere carbon system has varied greatly over geological history both in response to initial evolutionary innovation, and as a driver of adaptive change. Here we establish that positive selection in Rubisco, the most abundant enzyme on the Earth responsible for all photosynthetic carbon fixation, occurred early in Earth's history, and basal to the radiation of the modern marine algal groups. Our signals of positive selection appear to be triggered by changing intracellular concentrations of carbon dioxide (CO2) due to the emergence of carbon concentrating mechanisms between 1.56 and 0.41 Ba in response to declining atmospheric CO2 . We contend that, at least in terms of carbon, phytoplankton generally were well poised to manage subsequent abrupt carbon cycle perturbations. The physiological pathways for optimising carbon acquisition across a wide range of ambient carbon dioxide concentrations had already been established and were genetically widespread across open ocean phytoplankton groups. We will further investigate some case studies from the Mesozoic and Cenozoic abrupt carbon cycle excursions using isotopic tools to probe the community photosynthetic response and demonstrate the flexibility of phytoplankton photosynthesis in the face of major perturbations. In particular, an unprecedented resolution record across the Toarcian (Early Jurassic) carbon isotope excursion in the Paris Basin reveals a selection and evolution towards a community reliant solely on diffusive carbon dioxide supply for photosynthesis at the height of the excursion at 1500-2500 ppm CO2. The continued flourishing of the phytoplankton biological pump throughout this excursion was able to remove the excess carbon injected into the water column in less than 45 kyrs.

The effect of different unstable footwear constructions on centre of pressure motion during standing.

PubMed

Plom, W; Strike, S C; Taylor, M J D

2014-06-01

The aim of this study was to test the effect different unstable footwear constructions have on centre of pressure motion when standing. Sixteen young female volunteers were tested in five conditions, three unstable footwear (Reebok Easy-Tone, FitFlop and Skechers Shape-Ups), a standard shoe and barefoot in a randomised order. Double and single leg balance on a force plate was assessed via centre of pressure excursions and displacements in each condition. For double leg and single leg standing centre of pressure excursions in the anterior-posterior direction were significantly increased wearing Skechers Shape-Ups compared to barefoot and the standard shoe. For the Reebok Easy Tone during single leg standing excursions in the anterior-posterior direction were significantly greater compared to the barefoot condition. Cumulative displacement of the centre of pressure in medial-lateral direction increased significantly during single leg standing when wearing Skechers Shape-Ups compared to barefoot and standard shoe as well as for Reebok Easy Tone vs. barefoot. It would appear from these quiet standing results that the manner of the construction of instability shoes effects the CoP movement which is associated with induced instability. Greater CoP excursion occurred in the A-P direction while the cumulative displacements were greater in the M-L direction for those shoes with the rounded sole and soft foam and those with airpods. The shoe construction with altered density foam did not induce any change in the CoP movement, during quite standing, which tends to suggest that it is not effective at inducing balance. Not all instability shoes are effective in altering the overall instability of the wearer. Copyright © 2014 Elsevier B.V. All rights reserved.

Sonographic assessment of changes in diaphragmatic kinetics induced by inspiratory resistive loading.

PubMed

Soilemezi, Eleni; Tsagourias, Matthew; Talias, Michael A; Soteriades, Elpidoforos S; Makrakis, Vasilios; Zakynthinos, Epaminondas; Matamis, Dimitrios

2013-04-01

Diaphragmatic breathing patterns under resistive loading remain poorly documented. To our knowledge, this is the first study assessing diaphragmatic motion under conditions of inspiratory resistive loading with the use of sonography. We assessed diaphragmatic motion during inspiratory resistive loading in 40 healthy volunteers using M-mode sonography. In phase I of the study, sonography was performed during normal quiet breathing without respiratory loading. In phase II, sonography was performed after application of a nose clip and connection of the subjects to a pneumotachograph through a mouth piece. In phase III, the participants were assessed while subjected to inspiratory resistive loading of 50 cm H(2)O/L/s. Compared with baseline, the application of a mouth piece and nose clip induced a significant increase in diaphragmatic excursion (from 1.7 to 2.3 cm, P < 0.001) and a decrease in respiratory rate (from 13.4 to 12.2, P < 0.01). Inspiratory resistive loading induced a further decrease in respiratory rate (from 12.2 to 8.0, P < 0.01) and a decrease in diaphragmatic velocity contraction (from 1.2 to 0.8 cm/s, P < 0.01), and also an increase in tidal volume (from 795 to 904 mL, P < 0.01); diaphragmatic excursion, however, did not change significantly. Inspiratory resistive loading induced significant changes in diaphragmatic contraction pattern, which mainly consisted of decreased velocity of diaphragmatic displacement with no change in diaphragmatic excursion. Tidal volume, increased significantly; the increase in tidal volume, along with the unchanged diaphragmatic excursion, provides sonographic evidence of increased recruitment of extradiaphragmatic muscles under inspiratory resistive loading. © 2013 The Authors. Respirology © 2013 Asian Pacific Society of Respirology.

Impact of incretin on early-phase insulin secretion and glucose excursion.

PubMed

Shen, Jie; Chen, Zhi; Chen, Chaofeng; Zhu, Xiao; Han, Yajuan

2013-10-01

This study investigated the impact of incretin on early-phase insulin secretion and glucose excursion. The normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and type 2 diabetes mellitus (T2DM) groups included 16, 8, and 19 subjects, respectively. Subjects underwent continuous glucose monitoring for 3 days, followed by an oral glucose tolerance test. Plasma glucose, insulin, glucagon, total glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide-l (GLP-1) levels were measured at 30-min increments for 2 h after glucose intake. Differences with P < 0.05 were considered statistically significant. The area under the curve (AUC) of total GIP (120-min GIP-AUC) of the T2DM group was significantly lower than those of the NGT and IGT groups. The 120-min GLP-1-AUC of the NGT group was significantly larger than those of the T2DM and IGT groups. The early-phase insulin secretion index (ΔI30/ΔG30) of the T2DM group was significantly lower than those of the NGT and IGT groups. Mean amplitudes of glycemic excursions (MAGEs) went in the order of NGT < IGT < T2DM (P < 0.01, IGT vs. NGT; P < 0.001, T2DM vs. IGT). The 120-min GIP-AUC was negatively correlated with MAGE (r = -0.464), but uncorrelated with ΔI30/ΔG30. The 120-min GLP-1-AUC was positively correlated with ΔI30/ΔG30 (r = 0.580), but negatively correlated with MAGE (r = -0.606). Incretin may ameliorate glucose excursions, and GLP-1 may exert them by promoting early-phase insulin secretion. No correlation was observed between GIP secretion and early-phase insulin secretion.

Additive effects of acidification and mineralogy on calcium isotopes in Triassic/Jurassic boundary limestones

DOE PAGES

Jost, Adam B.; Bachan, Aviv; van de Schootbrugge, Bas; ...

2016-12-29

The end-Triassic mass extinction coincided with a negative δ 13 C excursion, consistent with release of 13C-depleted CO 2 from the Central Atlantic Magmatic Province. However, the amount of carbon released and its effects on ocean chemistry are poorly constrained. The co upled nature of the carbon and calcium cycles allows calcium isotopes to be used for constraining carbon cycle dynamics and vice versa. We present a high-resolution calcium isotope (δ 44/40 Ca) record from 100 m of marine limestone spanning the Triassic/Jurassic boundary in two stratigraphic sections from northern Italy. Immediately above the extinction horizon and the associated negativemore » excursion in δ 13 C, δ 44/40 Ca decreases by ca. 0.8‰ in 20 m of section and then recovers to preexcursion values. Coupled numerical models of the geological carbon and calcium cycles demonstrate that this δ 44/40 Ca excursion is too large to be explained by changes to seawater δ 44/40 Ca alone, regardless of CO 2 injection volume and duration. Less than 20% of the δ 44/40 Ca excursion can be attributed to acidification. The remaining 80% likely reflects a higher proportion of aragonite in the original sediment, based largely on high concentrations of Sr in the samples. Our study demonstrates that coupled models of the carbon and calcium cycles have the potential to help distinguish contributions of primary seawater isotopic changes from local or diagenetic effects on the δ 44/40 Ca of carbonate sediments. Finally, differentiating between these effects is critical for constraining the impact of ocean acidification during the end-Triassic mass extinction, as well as for interpreting other environmental events in the geologic past.« less

An Ecological Tipping Point Defined by Shallow Marine Foraminifera in the latest Paleocene

NASA Astrophysics Data System (ADS)

Robinson, M. M.; Spivey, W.

2016-12-01

The Paleocene-Eocene Thermal Maximum (PETM) is recognized in marine sediments by a carbonate dissolution zone, the extinction or turnover of benthic taxa, and a radiation of planktic excursion taxa, all accompanied by a rapid-onset, negative carbon isotope excursion (CIE). We present foraminiferal evidence from shallow marine sediments in southeastern Maryland, USA, where accumulation rates are high, for a minor ocean acidification event in the latest Paleocene that coincides with a relatively small (-2‰) CIE. This pre-onset excursion (POE) precedes the larger (-4‰) PETM CIE onset and dissolution event. During the POE, the benthic assemblage is reconfigured toward agglutinated species in order to adapt to increased acidity, and the planktic assemblage begins to speciate due to perturbed mixed layer conditions. The benthic assemblage returns to normal, without interruption, as the POE recovers, but planktic excursion taxa continue to appear in very low numbers. This is contrasted to the major ocean acidification event associated with the PETM CIE onset that results in a zone of complete dissolution followed by distinctive benthic and planktic foraminiferal assemblages. Our microfossil evidence documents a biotic response to bottom water and mixed layer perturbations that illustrates how coastal ecosystems react to both moderate and severe ocean acidification events, bracketing the ecological tipping point of shallow marine ecosystems. The POE, roughly half the magnitude of the CIE onset, provides insight into the nature of the initial effects of climate perturbation as well as an example of one that is fully recoverable. It is here that research aimed to better understand the long-term effects and reversibility of modern deteriorating oceanic conditions should focus. This study provides an initial metric by which to measure modern ecosystem disturbances and will help to define the tipping point for the shallow marine environment.

Finite element comparison of human and Hybrid III responses in a frontal impact.

PubMed

Danelson, Kerry A; Golman, Adam J; Kemper, Andrew R; Gayzik, F Scott; Clay Gabler, H; Duma, Stefan M; Stitzel, Joel D

2015-12-01

The improvement of finite element (FE) Human Body Models (HBMs) has made them valuable tools for investigating restraint interactions compared to anthropomorphic test devices (ATDs). The objective of this study was to evaluate the effect of various combinations of safety restraint systems on the sensitivity of thoracic injury criteria using matched ATD and Human Body Model (HBM) simulations at two crash severities. A total of seven (7) variables were investigated: 3-point belt with two (2) load limits, frontal airbag, knee bolster airbag, a buckle pretensioner, and two (2) delta-v's - 40kph and 50kph. Twenty four (24) simulations were conducted for the Hybrid III ATD FE model and repeated with a validated HBM for 48 total simulations. Metrics tested in these conditions included sternum deflection, chest acceleration, chest excursion, Viscous Criteria (V*C) criteria, pelvis acceleration, pelvis excursion, and femur forces. Additionally, chest band deflection and rib strain distribution were measured in the HBM for additional restraint condition discrimination. The addition of a frontal airbag had the largest effect on the occupant chest metrics with an increase in chest compression and acceleration but a decrease in excursion. While the THUMS and Hybrid III occupants demonstrated the same trend in the chest compression measurements, there were conflicting results in the V*C, acceleration, and displacement metrics. Similarly, the knee bolster airbag had the largest effect on the pelvis with a decrease in acceleration and excursion. With a knee bolster airbag the simulated occupants gave conflicting results, the THUMS had a decrease in femur force and the ATD had an increase. Preferential use of dummies or HBM's is not debated; however, this study highlights the ability of HBM metrics to capture additional chest response metrics. Copyright © 2015 Elsevier Ltd. All rights reserved.

Carbon associated nitrate (CAN) in the Ediacaran Johnnie Formation, Death Valley, California and links to the Shuram negative carbon isotope excursion

NASA Astrophysics Data System (ADS)

Dilles, Z. Y. G.; Prokopenko, M. G.; Bergmann, K.; Loyd, S. J.; Corsetti, F. A.; Berelson, W.; Gaines, R. R.

2014-12-01

Nitrogen, a major nutrient of marine primary production whose many redox states are linked through biological processes to O2, may afford better understanding of changes in post-Great Oxidation Event (GOE) environmental redox conditions. Using a novel approach to quantify nitrate content in carbonates, we identified a trend of CAN increase in the late-Proterozoic, including several distinct peaks within a carbonate succession of the Sonora province, Mexico, deposited ~630-500 Ma. The goal of the current study was to investigate CAN variability in the context of the global "Shuram" event, a large negative δ13C excursion expressed in Rainstorm member carbonates of the Johnnie Formation in Death Valley, CA. The lower Rainstorm Member "Johnnie Oolite", a time-transgressive, regionally extensive, shallow dolomitic oolite, was sampled. CAN concentrations ranged from 7.31 to 127.36 nmol/g, with higher values measured toward the base of the bed. This trend held at each sampled locality, along with a tendency towards decreasing CAN with larger magnitude negative δ13C excursions. Modern analog ooids formed in low-latitude marine environments lack CAN, consistent with their formation in low-nitrate waters of the euphotic zone characteristic of the modern ocean nitrogen cycling. In contrast, maximum values within the Johnnie oolite exceed by a factor of five to seven CAN measured in carbonates deposited below the main nitracline in the modern ocean, implying high nitrate content within shallow depositional environments. Johnnie oolite data, broadly consistent with the Sonora sequence findings, may indicate large perturbations in the Ediacaran nitrogen cycle immediately preceding the negative δ13C excursion. The implication of these findings for possible changes in the Ediacaran nitrogen, oxygen and carbon biogeochemical cycling will be further discussed.

Additive effects of acidification and mineralogy on calcium isotopes in Triassic/Jurassic boundary limestones

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

Jost, Adam B.; Bachan, Aviv; van de Schootbrugge, Bas

The end-Triassic mass extinction coincided with a negative δ 13 C excursion, consistent with release of 13C-depleted CO 2 from the Central Atlantic Magmatic Province. However, the amount of carbon released and its effects on ocean chemistry are poorly constrained. The co upled nature of the carbon and calcium cycles allows calcium isotopes to be used for constraining carbon cycle dynamics and vice versa. We present a high-resolution calcium isotope (δ 44/40 Ca) record from 100 m of marine limestone spanning the Triassic/Jurassic boundary in two stratigraphic sections from northern Italy. Immediately above the extinction horizon and the associated negativemore » excursion in δ 13 C, δ 44/40 Ca decreases by ca. 0.8‰ in 20 m of section and then recovers to preexcursion values. Coupled numerical models of the geological carbon and calcium cycles demonstrate that this δ 44/40 Ca excursion is too large to be explained by changes to seawater δ 44/40 Ca alone, regardless of CO 2 injection volume and duration. Less than 20% of the δ 44/40 Ca excursion can be attributed to acidification. The remaining 80% likely reflects a higher proportion of aragonite in the original sediment, based largely on high concentrations of Sr in the samples. Our study demonstrates that coupled models of the carbon and calcium cycles have the potential to help distinguish contributions of primary seawater isotopic changes from local or diagenetic effects on the δ 44/40 Ca of carbonate sediments. Finally, differentiating between these effects is critical for constraining the impact of ocean acidification during the end-Triassic mass extinction, as well as for interpreting other environmental events in the geologic past.« less

Short-term mechanisms of toxic action of airborne particulates underlie dose-rate dependent health risks and support control of one-hour airborne particle levels

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

Michaels, R.A.; Kleinman, M.T.

1999-07-01

Twenty-four-hour airborne particle mass levels permissible under the NAAQS have been associated with mortality and morbidity in communities, motivating reconsideration of the standard. Reports of shorter-term mechanisms of toxic action exerted by airborne PM and PM constituents are emerging. The mechanisms are diverse, but have in common a short time frame of toxic action, from minutes to hours. In view of documented PM excursions also lasting minutes to hours, this study inquires whether such short-term mechanisms might contribute to explaining daily morbidity and mortality. Toxicology experiments have demonstrated the harmfulness of brief exposure to PM levels in the range ofmore » observed excursions. This suggests that toxicological processes initiated by short-term inhalation of PM may exert clinically important effects, and that weak associations of 24-hour-average particle mass with mortality and morbidity may represent artifacts of stronger, shorter-term associations whose full magnitude remains to be quantified. In one study, the area of lung surface developing lesions was elevated in rats breathing the same four-hour dose of aerosols, when the four-hour average rate of aerosol delivery included a short-term (five-minute) burst fifty percent above the average dose rate. Elevations were observed with each of two aerosols tested. The magnitude of the effect was higher with one of the two aerosols, whose dose rate included four excursions rather than just one excursion. Particulate matter inhaled or instilled intratracheally has produced morbidity in animals, including apnea and electrophysiological effects in dogs. Other studies reveal that PM can kill rats via electrophysiological and possibly other mechanisms. PM has also adversely affected asthmatic people in controlled clinical settings during exercise or, in one study, at rest.« less

The Mediolateral Excursion of the Meniscal Bearing during Flexion and Extension of the Knee after Medial Mobile-Bearing Unicompartmental Knee Arthroplasty.

PubMed

Lee, Seung-Yup; Bae, Ji-Hoon; Suh, Dong-Won; Kim, Han-Ju; Lim, Hong-Chul

2017-02-01

This mediolateral excursion of the bearing during knee motion is supposed to be caused by external rotation of the tibia during knee extension. However, to our knowledge, there is no published clinical evidence supporting these hypotheses. The current study aimed to evaluate the mediolateral excursion of the bearing during flexion-extension motion of the knee after medial unicompartmental knee arthroplasty (UKA). In 52 knees, varus/valgus (F-VarVal) or rotational position (F-Rot) of the femoral component and relative location of the bearing were measured with the standing anteroposterior and modified axial view, respectively. We adopted the modified axial radiographs that are simple to assess the bearing position in the flexed knee. The modified axial view showed excellent inter- and intraobserver agreements. F-Rot in the modified axial view and CT showed a high agreement in terms of validity (r = 0.98; p  < 0.0001). On average, the bearing showed more medial position in extension than flexion of the knee. No correlation was found between the femoral component positions (F-VarVal and F-Rot) and mediolateral bearing excursion ( p  = 0.68 and 0.80, respectively). In conclusion, coronal location of bearing according to flexion-extension of the knee is not influenced by the coronal and axial alignment of the femoral component. With simple radiographic method, more medial position of the bearing according to flexion-extension of the knee. Our method could be used to assess axial rotation of the femoral component and spin-out phenomenon of the bearing following the medial UKA. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Reduced Bearing Excursion After Mobile-Bearing Unicompartmental Knee Arthroplasty is Associated With Poor Functional Outcomes.

PubMed

Wahal, Naman; Gaba, Sahil; Malhotra, Rajesh; Kumar, Vijay; Pegg, Elise C; Pandit, Hemant

2018-02-01

A small proportion of patients with mobile unicompartmental knee arthroplasty (UKA) report poor functional outcomes in spite of optimal component alignment on postoperative radiographs. The purpose of this study is to assess whether there is a correlation between functional outcome and knee kinematics. From a cohort of consecutive cases of 150 Oxford medial UKA, patients with fair/poor functional outcome at 1-year postsurgery (Oxford Knee Score [OKS] < 34, n = 15) were identified and matched for age, gender, preoperative clinical scores, and follow-up period with a cohort of patients with good/excellent outcome (OKS ≥ 34, n = 15). In vivo kinematic assessment was performed using step-up and deep knee bend exercises under fluoroscopic imaging. The fluoroscopic videos were analyzed using MATLAB software to measure the variation in time taken to complete the exercises, patellar tendon angle, and bearing position with knee flexion angle. Mean OKS in the fair/poor group was 29.9 and the mean OKS in the good/excellent group was 41.1. The tibial slope, time taken to complete the exercises, and patellar tendon angle trend over the flexion range were similar in both the groups; however, bearing position and the extent of bearing excursion differed significantly. The total bearing excursion in the OKS < 34 group was significantly smaller than the OKS ≥ 34 group (35%). Furthermore, on average, the bearing was positioned 1.7 mm more posterior on the tibia in the OKS < 34 group. This study provides evidence that abnormal knee kinematics, in particular bearing excursion and positioning, are associated with worse functional outcomes after mobile UKA. Copyright © 2017 Elsevier Inc. All rights reserved.

Reliability and comparison of trunk and pelvis angles, arm distance and center of pressure in the seated functional reach test with and without foot support in children.

PubMed

Radtka, Sandra; Zayac, Jacqueline; Goldberg, Krystyna; Long, Michael; Ixanov, Rustem

2017-03-01

This study determined test-retest reliability of trunk and pelvis joint angles, arm distance and center of pressure (COP) excursion for the seated functional reach test (FRT) and compared these variables during the seated FRT with and without foot support. Fifteen typically developing children (age 9.3±4.1years) participated. Trunk and pelvis joint angles, arm distance, and COP excursion were collected on two days using three-dimensional motion analysis and a force plate while subjects reached maximally with and without foot support in the anterior, anterior/lateral, lateral, posterior/lateral directions. Age, weight, height, trunk and arm lengths were correlated (p<0.01) with maximum arm distance reached. Maximum arm distance, trunk and pelvis joint angles, and COP with and without foot support were not significant (p<0.05) for the two test periods. Excellent reliability (ICCs>0.75) was found for maximum arm distance reached in all four directions in the seated FRT with and without foot support. Most trunk and pelvis joint angles and COP excursions during maximum reach in all four directions showed excellent to fair reliability (ICCs>0.40-0.75). Reaching with foot support in all directions was significantly greater (p<0.05) than without foot support; however, most COP excursions and trunk and pelvic angles were not significantly different. Findings support the addition of anterior/lateral and posterior/lateral reaching directions in the seated FRT. Trunk and pelvis movement analysis is important to examine in the seated FRT to determine the specific movement strategies needed for maximum reaching without loss of balance. Copyright © 2017 Elsevier B.V. All rights reserved.

IODP Expedition 303 (North Atlantic): Excursions and Reversals in the Brunhes and Matuyama Chrons

NASA Astrophysics Data System (ADS)

Channell, J. E.; Mazaud, A.; Stoner, J. S.

2005-12-01

The primary objective of IODP Expedition 303 (Sept.-Nov., 2004) was to recover complete and continuous records of Pliocene-Quaternary millennial-scale environmental and geomagnetic variability, and place these records into high-resolution isotopic and magnetic stratigraphies (including relative paleointensity). Some of the Exp. 303 site locations (Orphan Knoll, Eirik and Gardar Drifts, and DSDP Site 609) have already been instrumental in developing marine records of suborbital climate variability for the last climate cycle, and the goal of Exp. 303 was to extend the records back through the Quaternary and into the Pliocene. High mean sedimentation rates (15-20 cm/ky) at sites located on Orphan Knoll (Site U1302/3), Eirik Drift (Sites U1305 and U1306) and Gardar Drift (Site U1304) have resulted in shipboard records of excursions and reversals in the Brunhes and Matuyama Chrons. Site U1308 (DSDP Site 609) has lower mean sedimentation rate (7.9 cm/kyr) and extends the record into the Gauss Chron to ~3.1 Ma. Initial u-channel magnetic data support the existence of a number of polarity excursions in the Matuyama Chron, but only a single polarity excursion (Iceland Basin Event) has so far been observed in the Brunhes Chron. The Matuyama-Brunhes (M-B) polarity reversal yields virtual geomagnetic polar (VGP) paths that are reminiscent of those recovered from the northern Gardar and Bjorn drifts during ODP Leg 162. VGP clusters in the South Atlantic and off NE Asia accompany a Pacific loop, in what appears to be a repetitive but complex pattern for the M-B transition recorded in 9 holes from three Exp. 303 North Atlantic sites.

Strategies adopted by younger and older adults while operating a non-pedal tricycle.

PubMed

Calve, Tatiane; Russo Júnior, Douglas Vicente; Barela, Ana Maria Forti

Exercises that could prevent gait impairment of older adults should be implemented in such a way that practitioners can keep motivation and adherence independent of older adults fitness levels. This study describes how younger and older adults use a non-pedal tricycle to transport their bodies along a pathway. Nine younger (24±4.9y) and nine older (66±4.0y) adults participated in this study. They moved along a straight pathway at a self-selected comfortable speed with reflective markers on their main lower limb landmarks. A computerized gait analysis system with infrared cameras was used to obtain kinematic data to calculate spatial-temporal parameters and lower limb angles. Overall, participants from both groups were able to perform the task moving at a similar mean speed, with similar stride length and ankle joint excursion. Older adults had higher cadence (mean difference of 17steps/min; 95% CI=0.99-1.15) and hip excursion (mean difference of 12°; 95% CI=28-33), longer stance duration (mean difference of 3.4%; 95% CI=56.2-59.5), and lower knee excursion (mean difference of 6°; 95% CI=47.9-53.8) than younger adults. Older adults were able to transport their body with a non-pedal tricycle with more hip and less knee excursion than younger adults. Professionals that work with the older population should look at and take into consideration the use of non-pedal tricycles in exercise protocols and investigate the long-term impacts. Copyright © 2017 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.

Serial Testing of Postural Control After Acute Lateral Ankle Sprain

PubMed Central

Buckley, W. E.; Denegar, Craig R.

2001-01-01

Objective: To identify subjects' changes in postural control during single-leg stance in the 4 weeks after acute lateral ankle sprain. Design and Setting: We used a 2 × 2 × 3 (side-by-plane-by-session) within-subjects design with repeated measures on all 3 factors. All tests were performed in a university laboratory. Subjects: Seventeen young adults (9 men, 8 women; age, 21.8 ± 5.9 years; mass, 74.9 ± 10.5 kg; height, 176.9 ± 7.1 cm) who had sustained unilateral acute mild or moderate lateral ankle sprains. Measurements: Measures of center-of-pressure excursion length, root mean square velocity of center-of-pressure excursions (VEL), and range of center-of-pressure excursions (RANGE) were calculated separately in the frontal and sagittal planes during 5-second trials of static single-leg stance. Results: We noted significant side-by-plane-by-session interactions for magnitude of center-of-pressure excursions in a given trial (PSL) (P = .004), VEL (P = .011), and RANGE (P = .009). Both PSL and VEL in the frontal plane were greater in the injured limbs compared with the uninjured limbs on day 1 and during week 2 but not during week 4, whereas sagittal-plane differences existed during all 3 testing sessions. Injured-limb, frontal-plane RANGE scores were greater than uninjured values at day 1 but not during weeks 2 or 4. No significant differences in sagittal-plane RANGE scores were seen. Conclusions: Postural control was significantly impaired in the injured limbs at day 1 and during week 2 after lateral ankle sprain but not during week 4. Consistent improvement in postural control measures on both injured and uninjured limbs was seen throughout the 4 weeks after ankle sprain. PMID:12937477

The median density of the Universe

NASA Astrophysics Data System (ADS)

Stücker, Jens; Busch, Philipp; White, Simon D. M.

2018-03-01

Despite the fact that the mean matter density of the universe has been measured to an accuracy of a few percent within the standard ΛCDM paradigm, its median density is not known even to order of magnitude. Typical points lie in low-density regions and are not part of a collapsed structure of any scale. Locally, the dark matter distribution is then simply a stretched version of that in the early universe. In this single-stream regime, the distribution of unsmoothed density is sensitive to the initial power spectrum on all scales, in particular on very small scales, and hence to the nature of the dark matter. It cannot be estimated reliably using conventional cosmological simulations because of the enormous dynamic range involved, but a suitable excursion set procedure can be used instead. For the Planck cosmological parameters, a 100 GeV WIMP, corresponding to a free-streaming mass ˜10-6M⊙, results in a median density of ˜4 × 10-3 in units of the mean density, whereas a 10 μeV axion with free-streaming mass ˜10-12M⊙ gives ˜3 × 10-3, and Warm Dark Matter with a (thermal relic) mass of 1 keV gives ˜8 × 10-2. In CDM (but not in WDM) universes, single-stream regions are predicted to be topologically isolated by the excursion set formalism. A test by direct N-Body simulations seems to confirm this prediction, although it is still subject to finite size and resolution effects. Unfortunately, it is unlikely that any of these properties is observable and so suitable for constraining the properties of dark matter.

The median density of the Universe

NASA Astrophysics Data System (ADS)

Stücker, Jens; Busch, Philipp; White, Simon D. M.

2018-07-01

Despite the fact that the mean matter density of the Universe has been measured to an accuracy of a few per cent within the standard Λcold dark matter (ΛCDM) paradigm, its median density is not known even to the order of magnitude. Typical points lie in low-density regions and are not part of a collapsed structure of any scale. Locally, the dark matter distribution is then simply a stretched version of that in the early Universe. In this single-stream regime, the distribution of unsmoothed density is sensitive to the initial power spectrum on all scales, in particular on very small scales, and hence to the nature of the dark matter. It cannot be estimated reliably using conventional cosmological simulations because of the enormous dynamic range involved, but a suitable excursion set procedure can be used instead. For the Planck cosmological parameters, a 100 GeV WIMP, corresponding to a free-streaming mass ˜10-6M⊙, results in a median density of ˜4 × 10-3 in units of the mean density, whereas a 10 μeV axion with free-streaming mass ˜10-12M⊙ gives ˜3 × 10-3, and warm dark matter (WDM) with a (thermal relic) mass of 1 keV gives ˜8 × 10-2. In CDM (but not in WDM) universes, single-stream regions are predicted to be topologically isolated by the excursion set formalism. A test by direct N-body simulations seems to confirm this prediction, although it is still subject to finite size and resolution effects. Unfortunately, it is unlikely that any of these properties is observable and so suitable for constraining the properties of dark matter.

Topology of microwave background fluctuations - Theory

NASA Technical Reports Server (NTRS)

Gott, J. Richard, III; Park, Changbom; Bies, William E.; Bennett, David P.; Juszkiewicz, Roman

1990-01-01

Topological measures are used to characterize the microwave background temperature fluctuations produced by 'standard' scenarios (Gaussian) and by cosmic strings (non-Gaussian). Three topological quantities: total area of the excursion regions, total length, and total curvature (genus) of the isotemperature contours, are studied for simulated Gaussian microwave background anisotropy maps and then compared with those of the non-Gaussian anisotropy pattern produced by cosmic strings. In general, the temperature gradient field shows the non-Gaussian behavior of the string map more distinctively than the temperature field for all topology measures. The total contour length and the genus are found to be more sensitive to the existence of a stringy pattern than the usual temperature histogram. Situations when instrumental noise is superposed on the map, are considered to find the critical signal-to-noise ratio for which strings can be detected.

Beyond Reason: Eight Great Problems That Reveal the Limits of Science

NASA Astrophysics Data System (ADS)

Dewdney, A. K.

2004-04-01

A mind-bending excursion to the limits of science and mathematics Are some scientific problems insoluble? In Beyond Reason, internationally acclaimed math and science author A. K. Dewdney answers this question by examining eight insurmountable mathematical and scientific roadblocks that have stumped thinkers across the centuries, from ancient mathematical conundrums such as "squaring the circle," first attempted by the Pythagoreans, to G?del's vexing theorem, from perpetual motion to the upredictable behavior of chaotic systems such as the weather. A. K. Dewdney, PhD (Ontario, Canada), was the author of Scientific American's "Computer Recreations" column for eight years. He has written several critically acclaimed popular math and science books, including A Mathematical Mystery Tour (0-471-40734-8); Yes, We Have No Neutrons (0-471-29586-8); and 200% of Nothing (0-471-14574-2).

The sun since the Bronze Age

NASA Technical Reports Server (NTRS)

Eddy, J. A.

1976-01-01

An investigation is conducted concerning the behavior of the sun during the last 7000 years. The C-14 content in carbonaceous fossil material can be used as an indicator regarding the level of solar activity at the time when the carbon was assimilated in the process of photosynthesis. Living trees, such as the bristlecone pine, provide a solar activity record to about 3000 B.C. The record can be extended with the aid of well-preserved dead wood to beyond 5000 B.C. The results of an analysis of solar activity levels as a function of time on the basis of C-14 contents are presented in a graph. Attention is given to the Maunder Minimum, a history of the sun in the last 5000 years, an interpretation of the major C-14 excursions, and the sun and climate history.

Evaluation of the Inertial Response of Variable-Speed Wind Turbines Using Advanced Simulation: Preprint

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

Scholbrock, Andrew K; Muljadi, Eduard; Gevorgian, Vahan

In this paper, we focus on the temporary frequency support effect provided by wind turbine generators (WTGs) through the inertial response. With the implemented inertial control methods, the WTG is capable of increasing its active power output by releasing parts of the stored kinetic energy when the frequency excursion occurs. The active power can be boosted temporarily above the maximum power points, but the rotor speed deceleration follows and an active power output deficiency occurs during the restoration of rotor kinetic energy. In this paper, we evaluate and compare the inertial response induced by two distinct inertial control methods usingmore » advanced simulation. In the first stage, the proposed inertial control methods are analyzed in offline simulation. Using an advanced wind turbine simulation program, FAST with TurbSim, the response of the researched wind turbine is comprehensively evaluated under turbulent wind conditions, and the impact on the turbine mechanical components are assessed. In the second stage, the inertial control is deployed on a real 600-kW wind turbine, the three-bladed Controls Advanced Research Turbine, which further verifies the inertial control through a hardware-in-the-loop simulation. Various inertial control methods can be effectively evaluated based on the proposed two-stage simulation platform, which combines the offline simulation and real-time hardware-in-the-loop simulation. The simulation results also provide insights in designing inertial control for WTGs.« less

Estimation of Quasi-Stiffness of the Human Hip in the Stance Phase of Walking

PubMed Central

Shamaei, Kamran; Sawicki, Gregory S.; Dollar, Aaron M.

2013-01-01

This work presents a framework for selection of subject-specific quasi-stiffness of hip orthoses and exoskeletons, and other devices that are intended to emulate the biological performance of this joint during walking. The hip joint exhibits linear moment-angular excursion behavior in both the extension and flexion stages of the resilient loading-unloading phase that consists of terminal stance and initial swing phases. Here, we establish statistical models that can closely estimate the slope of linear fits to the moment-angle graph of the hip in this phase, termed as the quasi-stiffness of the hip. Employing an inverse dynamics analysis, we identify a series of parameters that can capture the nearly linear hip quasi-stiffnesses in the resilient loading phase. We then employ regression analysis on experimental moment-angle data of 216 gait trials across 26 human adults walking over a wide range of gait speeds (0.75–2.63 m/s) to obtain a set of general-form statistical models that estimate the hip quasi-stiffnesses using body weight and height, gait speed, and hip excursion. We show that the general-form models can closely estimate the hip quasi-stiffness in the extension (R2 = 92%) and flexion portions (R2 = 89%) of the resilient loading phase of the gait. We further simplify the general-form models and present a set of stature-based models that can estimate the hip quasi-stiffness for the preferred gait speed using only body weight and height with an average error of 27% for the extension stage and 37% for the flexion stage. PMID:24349136

Dynamics of foraging trails in the Neotropical termite Velocitermes heteropterus (Isoptera: Termitidae).

PubMed

Haifig, Ives; Jost, Christian; Fourcassié, Vincent; Zana, Yossi; Costa-Leonardo, Ana Maria

2015-09-01

Foraging behavior in termites varies with the feeding habits of each species but often occurs through the formation of well-defined trails that connect the nest to food sources in species that build structured nests. We studied the formation of foraging trails and the change in caste ratio during foraging in the termite Velocitermes heteropterus. This species is widespread in Cerrado vegetation where it builds epigeal nests and forages in open-air at night. Our aim was to understand the processes involved in the formation of foraging trails, from the exploration of new unmarked areas to the recruitment of individuals to food and the stabilization of traffic on the trails, as well as the participation of the different castes during these processes. Foraging trails were videotaped in the laboratory and the videos were then analyzed both manually and automatically to assess the flow of individuals and the caste ratio on the trails as well as to examine the spatial organization of traffic over time. Foraging trails were composed of minor workers, major workers, and soldiers. The flow of individuals on the trails gradually increased from the beginning of the exploration of new areas up to the discovery of the food. The caste ratio remained constant throughout the foraging excursion: major workers, minor workers and soldiers forage in a ratio of 8:1:1, respectively. The speed of individuals was significantly different among castes, with major workers and soldiers being significantly faster than minor workers. Overall, our results show that foraging excursions in V. heteropterus may be divided in three different phases, characterized by individual speeds, differential flows and lane segregation. Copyright © 2015 Elsevier B.V. All rights reserved.

Late quaternary temperature record from buried soils of the North American Great Plains

USGS Publications Warehouse

Nordt, L.; Von Fischer, J.; Tieszen, L.

2007-01-01

We present the first comprehensive late Quaternary record of North American Great Plains temperature by assessing the behavior of the stable isotopic composition (δ13C) of buried soils. After examining the relationship between the δ13C of topsoil organic matter and July temperature from 61 native prairies within a latitudinal range of 46°–38°N, we applied the resulting regression equation to 64 published δ13C values from buried soils of the same region to construct a temperature curve for the past 12 k.y. Estimated temperatures from 12 to 10 ka (1 k.y. = 1000 14C yr B.P.) fluctuated with a periodicity of ∼1 k.y. with two cool excursions between −4.5 and −3.5 °C and two warmer excursions between −1 and 0 °C, relative to modern. Early Holocene temperatures from ca. 10–7.5 ka were −1.0 to −2.0 °C before rising to +1.0 °C in the middle Holocene between 6.0 and 4.5 ka. After a cool interlude from 4.2 to 2.6 ka, when temperatures dropped to slightly below modern, another warm interval ensued from 2.6 to 1 ka as temperatures increased to ∼+0.5 °C. A final decline in temperature to below modern occurred beginning ca. 0.5 ka. Cooler than present temperatures in the Great Plains indicate telecommunications with cool-water episodes in the Gulf of Mexico and North Atlantic potentially governed by a combination of glacial meltwater pulses and low solar irradiance.

Effects of Pedal Speed and Crank Length on Pedaling Mechanics during Submaximal Cycling

PubMed Central

BARRATT, PAUL RICHARD; MARTIN, JAMES C.; ELMER, STEVE J.; KORFF, THOMAS

2016-01-01

ABSTRACT During submaximal cycling, the neuromuscular system has the freedom to select different intermuscular coordination strategies. From both a basic science and an applied perspective, it is important to understand how the central nervous system adjusts pedaling mechanics in response to changes in pedaling conditions. Purpose To determine the effect of changes in pedal speed (a marker of muscle shortening velocity) and crank length (a marker of muscle length) on pedaling mechanics during submaximal cycling. Methods Fifteen trained cyclists performed submaximal isokinetic cycling trials (90 rpm, 240 W) using pedal speeds of 1.41 to 1.61 m·s−1 and crank lengths of 150 to 190 mm. Joint powers were calculated using inverse dynamics. Results Increases in pedal speed and crank length caused large increases knee and hip angular excursions and velocities (P < 0.05), whereas ankle angular kinematics stayed relatively constant (P > 0.05). Joint moments and joint powers were less affected by changes in the independent variables, but some interesting effects and trends were observed. Most noteworthy, knee extension moments and powers tended to decrease, whereas hip extension power tended to increase with an increase in crank length. Conclusions The distribution of joint moments and powers is largely maintained across a range of pedaling conditions. The crank length induced differences in knee extension moments, and powers may represent a trade-off between the central nervous system’s attempts to simultaneously minimize muscle metabolic and mechanical stresses. These results increase our understanding of the neural and mechanical mechanisms underlying multi-joint task performance, and they have practical relevance to coaches, athletes, and clinicians. PMID:26559455

Decreased locomotor and investigatory exploration after denervation of catecholamine terminal fields in the forebrain of rats.

PubMed

Dubois, A B; Ogilvy, C S

1978-12-01

1. Pressures on the right and left sides of the tails of swimming bluefish were measured and found to have a range of +5.9 to -5.9 cm H2O. The pressures were resolved into their forward and lateral vectorial components of force to allow calculation of forward and lateral force and power at speeds ranging from 0.26 to 0.87 m/s. 2. The peak to peak changes in force of acceleration of the body, measured with a forward accelerometer averaged 209 g or 2.05 N at 0.48 m/s, and were compared with the maximum to minimum excursions of forward tail force averaging 201 g or 1.97 N at the same speed. The mean difference was 8 g, S.D. of the mean difference +/-29, SE. of mean difference +/-10 g. 3. Mean tail thrust was calculated as the time average of tail force in the forward direction. It averaged 65 g , or 0.64 N, at 0.48 m/s. The mean forward power was 0.34 N m/s at 0.48 m/s. The drag of the gauges and wires accounted for 10% of this figure. 4. The mean lateral power of the tail was 1.28 N m/s at a mean speed of 0.48 m/s. 5. The propulsive efficiency of the tail, calculated as the ratio of forward power to forward plus lateral power, was found to be 0.20 S.D.+/-0.04, S.E.+/-0.01 and was not related to speed. This suggests that 80% of the mechanical power of the tail was wasted. Turbulence in the water may have contributed to this large drag and low tail efficiency.

Jaw-muscle fiber architecture in tufted capuchins favors generating relatively large muscle forces without compromising jaw gape.

PubMed

Taylor, Andrea B; Vinyard, Christopher J

2009-12-01

Tufted capuchins (sensu lato) are renowned for their dietary flexibility and capacity to exploit hard and tough objects. Cebus apella differs from other capuchins in displaying a suite of craniodental features that have been functionally and adaptively linked to their feeding behavior, particularly the generation and dissipation of relatively large jaw forces. We compared fiber architecture of the masseter and temporalis muscles between C. apella (n=12) and two "untufted" capuchins (C. capucinus, n=3; C. albifrons, n=5). These three species share broadly similar diets, but tufted capuchins occasionally exploit mechanically challenging tissues. We tested the hypothesis that tufted capuchins exhibit architectural properties of their jaw muscles that facilitate relatively large forces including relatively greater physiologic cross-sectional areas (PCSA), more pinnate fibers, and lower ratios of mass to tetanic tension (Mass/P(0)). Results show some evidence supporting these predictions, as C. apella has relatively greater superficial masseter and temporalis PCSAs, significantly so only for the temporalis following Bonferroni adjustment. Capuchins did not differ in pinnation angle or Mass/P(0). As an architectural trade-off between maximizing muscle force and muscle excursion/contraction velocity, we also tested the hypothesis that C. apella exhibits relatively shorter muscle fibers. Contrary to our prediction, there are no significant differences in relative fiber lengths between tufted and untufted capuchins. Therefore, we attribute the relatively greater PCSAs in tufted capuchins primarily to their larger muscle masses. These findings suggest that relatively large jaw-muscle PCSAs can be added to the suite of masticatory features that have been functionally linked to the exploitation of a more resistant diet by C. apella. By enlarging jaw-muscle mass to increase PCSA, rather than reducing fiber lengths and increasing pinnation, tufted capuchins appear to have increased jaw-muscle and bite forces without markedly compromising muscle excursion and contraction velocity. One performance advantage of this morphology is that it promotes relatively large bite forces at wide jaw gapes, which may be useful for processing large food items along the posterior dentition. We further hypothesize that this morphological pattern may have the ecological benefit of facilitating the dietary diversity seen in tufted capuchins. Lastly, the observed feeding on large objects, coupled with a jaw-muscle architecture that facilitates this behavior, raises concerns about utilizing C. apella as an extant behavioral model for hominins that might have specialized on small objects in their diets.

Outbreaks of Gastroenteritis That Occurred during School Excursions in Korea Were Associated with Several Waterborne Strains of Norovirus

PubMed Central

Kim, Sung-Han; Cheon, Doo-Sung; Kim, Jin-Hyeun; Lee, Dong-Han; Jheong, Won-hwa; Heo, Young-Joo; Chung, Hyen-Mi; Jee, Youngmee; Lee, Joo-Shil

2005-01-01

In May 2004, 97 of 309 (31%) and 97 of 207 (47%) school students from geographically distant areas were affected by acute gastroenteritis during excursions to neighboring hotels. The two hotels were 300 m apart, on Jeju Island, South Korea. Several strains of norovirus, including both genogroup I and genogroup II viruses, were identified in stool samples from the students and food handlers and in groundwater from the hotels. Of these several strains of norovirus, the nucleotide sequences for one strain were identical for samples from the students, food handlers, and groundwater. PMID:16145153

Intermittent, noncyclic dysfunction of a mechanical aortic prosthesis by pannus formation.

PubMed

Giroux, Sylvie K; Labinaz, Marino X; Grisoli, Dominique; Klug, Andrew P; Veinot, John P; Burwash, Ian G

2010-01-01

Mechanical aortic prosthesis dysfunction can result from thrombosis or pannus formation. Pannus formation usually restricts systolic excursion of the occluding disk, resulting in progressive stenosis of the aortic prosthesis. Intermittent dysfunction of a mechanical aortic prosthesis is usually ascribed to thrombus formation. We describe an unusual case of intermittent, noncyclic dysfunction of a mechanical aortic prosthesis due to pannus formation in the absence of systolic restriction of disk excursion that presented with intermittent massive aortic regurgitation, severe ischemia, and shock. Pannus formation should be considered as a potential cause of acute intermittent severe aortic regurgitation in a patient with a mechanical aortic prosthesis.

Mercury enrichment indicates volcanic triggering of Valanginian environmental change

PubMed Central

Charbonnier, Guillaume; Morales, Chloé; Duchamp-Alphonse, Stéphanie; Westermann, Stéphane; Adatte, Thierry; Föllmi, Karl B.

2017-01-01

The Valanginian stage (Early Cretaceous) includes an episode of significant environmental changes, which are well defined by a positive δ13C excursion. This globally recorded excursion indicates important perturbations in the carbon cycle, which has tentatively been associated with a pulse in volcanic activity and the formation of the Paraná-Etendeka large igneous province (LIP). Uncertainties in existing age models preclude, however, its positive identification as a trigger of Valanginian environmental changes. Here we report that in Valanginian sediments recovered from a drill core in Wąwał (Polish Basin, Poland), and from outcrops in the Breggia Gorge (Lombardian Basin, southern Switzerland), and Orpierre and Angles (Vocontian Basin, SE France), intervals at or near the onset of the positive δ13C excursion are significantly enriched in mercury (Hg). The persistence of the Hg anomaly in Hg/TOC, Hg/phyllosilicate, and Hg/Fe ratios shows that organic-matter scavenging and/or adsorbtion onto clay minerals or hydrous iron oxides only played a limited role. Volcanic outgassing was most probably the primary source of the Hg enrichments, which demonstrate that an important magmatic pulse triggered the Valanginian environmental perturbations. PMID:28106091

Effect of eating vegetables before carbohydrates on glucose excursions in patients with type 2 diabetes

PubMed Central

Imai, Saeko; Fukui, Michiaki; Kajiyama, Shizuo

2014-01-01

The aim of this review was to evaluate whether eating vegetables before carbohydrates could reduce the postprandial glucose, insulin, and improve long-term glycemic control in Japanese patients with type 2 diabetes. We studied the effect of eating vegetables before carbohydrates on postprandial plasma glucose, insulin, and glycemic control for 2.5 y in patients with type 2 diabetes. The postprandial glucose and insulin levels decreased significantly when the patients ate vegetables before carbohydrates compared to the reverse regimen, and the improvement of glycemic control was observed for 2.5 y. We also compared the postprandial glucose and glucose fluctuations assessed by continuous glucose monitoring system for 72-h in patients with type 2 diabetes and subjects with normal glucose tolerance when subjects ate vegetables before carbohydrates and carbohydrates before vegetables in a randomized crossover design. The glycemic excursions and incremental glucose peak were significantly lower when the subjects ate vegetables before carbohydrates compared to the reverse regimen. This evidence supports the effectiveness of eating vegetables before carbohydrates on glucose excursions in the short-term and glycemic control in the long-term in patients with type 2 diabetes. PMID:24426184

Effect of eating vegetables before carbohydrates on glucose excursions in patients with type 2 diabetes.

PubMed

Imai, Saeko; Fukui, Michiaki; Kajiyama, Shizuo

2014-01-01

The aim of this review was to evaluate whether eating vegetables before carbohydrates could reduce the postprandial glucose, insulin, and improve long-term glycemic control in Japanese patients with type 2 diabetes. We studied the effect of eating vegetables before carbohydrates on postprandial plasma glucose, insulin, and glycemic control for 2.5 y in patients with type 2 diabetes. The postprandial glucose and insulin levels decreased significantly when the patients ate vegetables before carbohydrates compared to the reverse regimen, and the improvement of glycemic control was observed for 2.5 y. We also compared the postprandial glucose and glucose fluctuations assessed by continuous glucose monitoring system for 72-h in patients with type 2 diabetes and subjects with normal glucose tolerance when subjects ate vegetables before carbohydrates and carbohydrates before vegetables in a randomized crossover design. The glycemic excursions and incremental glucose peak were significantly lower when the subjects ate vegetables before carbohydrates compared to the reverse regimen. This evidence supports the effectiveness of eating vegetables before carbohydrates on glucose excursions in the short-term and glycemic control in the long-term in patients with type 2 diabetes.

Three-dimensional skeletal kinematics of the shoulder girdle and forelimb in walking Alligator

PubMed Central

Baier, David B; Gatesy, Stephen M

2013-01-01

Crocodylians occupy a key phylogenetic position for investigations of archosaur locomotor evolution. Compared to the well-studied hindlimb, relatively little is known about the skeletal movements and mechanics of the forelimb. In this study, we employed manual markerless XROMM (X-ray Reconstruction Of Moving Morphology) to measure detailed 3-D kinematics of the shoulder girdle and forelimb bones of American alligators (Alligator mississippiensis) walking on a treadmill. Digital models of the interclavicle, scapulocoracoid, humerus, radius and ulna were created using a 3-D laser scanner. Models were articulated and aligned to simultaneously recorded frames of fluoroscopic and standard light video to reconstruct and measure joint motion. Joint coordinate systems were established for the coracosternal, glenohumeral and elbow joints. Our analysis revealed that the limb joints only account for about half of fore/aft limb excursion; the remaining excursion results from shoulder girdle movements and lateral bending of the vertebral column. Considerable motion of each scapulocoracoid relative to the vertebral column is consistent with coracosternal mobility. The hemisellar design of the glenohumeral joint permits some additional translation, or sliding in the fore-aft plane, but this movement does not have much of an effect on the distal excursion of the bone. PMID:24102540

Advantage of bimodal fitting in prosody perception for children using a cochlear implant and a hearing aid.

PubMed

Straatman, L V; Rietveld, A C M; Beijen, J; Mylanus, E A M; Mens, L H M

2010-10-01

Cochlear implants are largely unable to encode voice pitch information, which hampers the perception of some prosodic cues, such as intonation. This study investigated whether children with a cochlear implant in one ear were better able to detect differences in intonation when a hearing aid was added in the other ear ("bimodal fitting"). Fourteen children with normal hearing and 19 children with bimodal fitting participated in two experiments. The first experiment assessed the just noticeable difference in F0, by presenting listeners with a naturally produced bisyllabic utterance with an artificially manipulated pitch accent. The second experiment assessed the ability to distinguish between questions and affirmations in Dutch words, again by using artificial manipulation of F0. For the implanted group, performance significantly improved in each experiment when the hearing aid was added. However, even with a hearing aid, the implanted group required exaggerated F0 excursions to perceive a pitch accent and to identify a question. These exaggerated excursions are close to the maximum excursions typically used by Dutch speakers. Nevertheless, the results of this study showed that compared to the implant only condition, bimodal fitting improved the perception of intonation.

Cinerama sickness and postural instability.

PubMed

Bos, Jelte E; Ledegang, Wietse D; Lubeck, Astrid J A; Stins, John F

2013-01-01

Motion sickness symptoms and increased postural instability induced by motion pictures have been reported in a laboratory, but not in a real cinema. We, therefore, carried out an observational study recording sickness severity and postural instability in 19 subjects before, immediately and 45 min after watching a 1 h 3D aviation documentary in a cinema. Sickness was significantly larger right after the movie than before, and in a lesser extent still so after 45 min. The average standard deviation of the lateral centre of pressure excursions was significantly larger only right afterwards. When low-pass filtered at 0.1 Hz, lateral and for-aft excursions were both significantly larger right after the movie, while for-aft excursions then remained larger even after 45 min. Speculating on previous findings, we predict more sickness and postural instability in 3D than in 2D movies, also suggesting a possible, but yet unknown risk for work-related activities and vehicle operation. Watching motion pictures may be sickening and posturally destabilising, but effects in a cinema are unknown. We, therefore, carried out an observational study showing that sickness then is mainly an issue during the exposure while postural instability is an issue afterwards.

A virtual, interactive and dynamic excursion in Google Earth on soil management and conservation (AgroGeovid)

NASA Astrophysics Data System (ADS)

Vanwalleghem, Tom; Giráldez, Juan Vicente

2013-04-01

Many courses on natural resources require hands-on practical knowledge and experience that students traditionally could only acquire by expensive and time-consuming field excursions. New technologies and social media however provide an interesting alternative to train students and help them improve their practical knowledge. AgroGeovid is a virtual excursion, based on Google Earth, Youtube, Facebook and Twitter that is aimed at agricultural engineering students, but equally useful for any student interested in soil management and conservation, e.g. geography, geology and environmental resources. Agrogeovid provides the framework for teachers and students to upload geotagged photos, comments and discussions. After the initial startup phase, where the teacher uploaded material on e.g. soil erosion phenomena, soil conservation structures and different soil management strategies under different agronomic systems, students contributed with their own material gathered throughout the academic year. All students decided to contribute via Facebook, in stead of Twitter, which was not known to most of them. The final result was a visual and dynamic tool which students could use to train and perfect skills adopted in the classroom using case-studies and examples from their immediate environment.

Stereometric Analysis Of Static Equilibrium In CNS Disorders

NASA Astrophysics Data System (ADS)

Sheffer, D. B.; Lehmkuhl, D. L.; Herron, R. E.

1980-07-01

A primary aim in the physical rehabilitation of individuals with severe head or spinal injuries resulting in hemiparesis, tetraparesis or paraparesis, is the restoration of the functional motor abilities controlling involved muscle groups. The regaining of trunk postural stability provides a valuable antecedent in the recovery of use of the arms and legs. Accurate objective infor-mation must be provided to the therapist for assessment of treatment regimes. At present, few objective practical methods are available to furnish this evaluative information. Therefore the purpose of this study was to investigate the use of a biostereometric range of motion sensor for recording and quantifying trunk static equilibrium in individuals ungergoing therapy for head trauma. The sensor located the relative position of the C-7 vertebrae of the patient in space using continual monitoring of spherical coordinates. Results of the test protocol included : plots of the movement of the trunk excursions, determination of the maximum area of excursion and a trunk sway index (the relationship of the maximum area, the total excursion distance and a time factor). Further results demonstrated that the biostereometric sensor yielded quantitative documentation of improvement in a patient undergoing therapy.

Short Magma Residence Times at Mt. Rainier and the Probable Absence of a Large, Integrated, and Long-lived Magma Reservoir System

NASA Astrophysics Data System (ADS)

Sisson, T. W.; Lanphere, M. A.

2003-12-01

Intensive, high-precision K-Ar and 40Ar/39Ar geochronology have proven essential for producing modern geologic maps of volcanoes and from these determining the volcanoes' time-volume histories. If sufficiently abundant, these data can also reveal aspects of the magma supply system. For Cascade volcanoes a general result has been the demonstration that edifice growth is highly episodic. Mount Rainier grew in the last 500,000 years atop the remains of an ancestral edifice that was active in the same location 1 - 2 Myr ago. The 500,000 year history of the modern edifice falls into four stages of alternating high and low magmatic output of subequal duration, but major and trace element compositions of eruptives show no correlation with volcano growth stages. Instead, the same spectrum of magmas (andesite to low-Si dacite) erupted throughout the history of the volcano with compositions in the same relative abundances. Superimposed on this seemingly null result are at least 6 brief but pronounced excursions in magma trace-element compositions. Concentrations of Zr, Ba, or Sr can double and then return to background values passing into and out of a single flow or flow-group. Some excursions are tightly bracketed by mapping and by measured ages and have durations no more than the geochronologic measurement precision of about 10,000 years. True excursion durations are potentially much shorter. The brevity and abrupt onsets and cessations of these compositional excursions are evidence against the presence of a sizeable, long-lived magma reservoir anywhere beneath the volcano, including a MASH zone in the lower crust, that would have attenuated, dampened, and homogenized compositional excursions introduced into the magmatic system. Instead, we take 10,000 years as a probable upper limit to the average residence time of magma batches transiting the crustal portion of Mount Rainier's plumbing system. A consistent scenario is that parental magmas enter the crust, differentiate, assimilate, and either erupt or solidify in less than 10,000 years. Geochronologic evidence from much larger magmatic systems (Reid and coworkers, Long Valley, Yellowstone) suggests that more productive systems can have much longer average residence times than modestly active arc stratovolcanoes like Mt. Rainier.

Effect of Subspine Decompression on Rectus Femoris Integrity and Iliopsoas Excursion: A Cadaveric Study.

PubMed

El-Shaar, Rami; Stanton, Michael; Biehl, Scott; Giordano, Brian

2015-10-01

To determine the relative influence of anteroinferior iliac spine (AIIS) or subspine decompression on proximal rectus femoris integrity and iliopsoas excursion throughout a physiological range of motion. Nineteen cadaveric hips from 10 specimens were dissected to retain the origin of the rectus femoris direct and indirect heads. The anatomic footprints of the origins were measured with calipers. Serial 5-mm resections of the AIIS were made to determine the extent of proximal tendon disruption that corresponded to each resection. Iliopsoas tendon tracking was also assessed after sequential AIIS decompression by measuring the excursion of the medial border of the iliopsoas tendon as it traveled from its native resting position to the point where it first encountered bony impingement at the AIIS. The mean proximal-distal footprint of the rectus femoris direct head was 17.95 ± 2.99 mm. The mean medial-lateral distance was 11.84 ± 2.34 mm. There was a consistent bare area along the inferior aspect of the AIIS that averaged 4.84 ± 1.42 mm. The average percentage of remaining footprint after each 5-mm resection (5 to 25 mm) was 96%, 65%, 35%, 14%, and 11%, respectively, with statistical significance noted after resections larger than 5 mm (P < .001). The native excursion distance of the iliopsoas tendon was 14.05 mm. With each 5-mm resection, the percentage of excursion before impingement on the AIIS increased by 18%, 45%, 72%, 95%, and 100%, respectively, which was statistically significance after all resections (P < .001). Our study maps the anatomic footprint of the direct head of the rectus femoris tendon and confirms a previously identified bare area along the inferior aspect of the AIIS. Female cadaveric hips had a significantly smaller rectus footprint than male cadavers in our study (P < .001). Subspine decompression greater than 10 mm significantly compromises the rectus femoris origin and should be avoided when performing arthroscopic AIIS decompression. In addition, subspine decompression significantly improves tracking of the iliopsoas tendon throughout a physiological range of motion and may be considered a surgical adjunct when treating symptomatic iliopsoas snapping. Arthroscopic subspine decompression serves as an important treatment modality for AIIS impingement. With a more thorough understanding of AIIS anatomy, subspine decompression can be used to relieve impingement symptoms and possibly improve iliopsoas tracking while safely maintaining rectus femoris footprint integrity. Published by Elsevier Inc.

Delayed recovery from the end-Triassic extinction due to an increase in the extent of ocean anoxia

NASA Astrophysics Data System (ADS)

Jost, A. B.; Bachan, A.; van de Schootbrugge, B.; Lau, K. V.; Weaver, K. L.; Maher, K.; Payne, J.

2015-12-01

The end-Triassic mass extinction was likely triggered by a rapid rise in pCO2 associated with the emplacement of the Central Atlantic Magmatic Province (CAMP) ca. 201 Ma. Shallow-marine anoxia has long been hypothesized to have caused the extinction and/or delayed the recovery of marine life. However, due to a lack of proxy data, the effects of CAMP emplacement on seawater chemistry remain poorly constrained. Local proxies for anoxia may not reflect widespread ocean redox conditions. However, coupled records of U concentration and isotopic composition (δ238U) in CaCO3 sediments precipitated beneath well-oxygenated bottom waters can potentially serve as a proxy for the global extent of anoxia due to fractionation of U during reduction and associated imbalances in the marine U cycle due to redox changes. We measured δ238U and Th/U values in shallow marine limestones from two stratigraphic sections in the Lombardy Basin, northern Italy, spanning over 400 m, to quantify the change in the extent of ocean anoxia during the end-Triassic extinction. We observe a ca. 0.6‰ negative excursion in δ238U beginning in the lowermost Jurassic, coeval with the onset of the negative δ13C excursion and persisting for the duration of subsequent high δ13C values in the lower-middle Hettangian (earliest Jurassic). Th/U values are generally low at the T/J boundary, peak near the nadir of the δ238U excursion, and steadily return to pre-event values by the end of the measured section. Using a numerical model of the U cycle, we demonstrate that this excursion corresponds to a thirty-fold increase in the extent of anoxia worldwide and a simultaneous increase in the riverine U flux, consistent with increased weathering and eutrophication following massive CO2 injection from CAMP volcanism. Scenarios involving an increase in marine anoxia would also predict higher rates of organic C burial, explaining the large protracted positive δ13C excursion in the lower-mid Hettangian. Recovery of marine fauna, particularly reef builders, was delayed until the late Hettangian, suggesting that environmental conditions were unfavorable for >1 My after the extinction. Uranium isotope data provide strong support for the hypothesis that persistent ocean anoxia inhibited biotic recovery throughout this interval.

Looking for the Kellwasser Event in all the wrong places: a multiproxy study of island arc paleoenvironments in the Central Asian Orogenic Belt

NASA Astrophysics Data System (ADS)

Carmichael, S. K.; Wang, Z.; Waters, J. A.; Dombrowski, A. D.; Batchelor, C. J.; Coleman, D. S.; Suttner, T.; Kido, E.

2017-12-01

The Late Devonian Frasnian-Famennian (F-F) boundary at 372 Ma is associated with the Kellwasser Event, an ocean anoxia event that is often associated with positive δ13C excursions and commonly represented by black shales. However, approximately 88% of the studies of the Kellwasser Event are based on sites from deep epicontinental basins and epeiric seas, and most of these sites are located on the Euramerican paleocontinent. In contrast to the positive δ13C excursions found in most basinal study sites, the δ13C signatures in three separate shallow water, island-arc F-F sections in the Junggar Basin in northwestern China (Wulankeshun, Boulongour Reservoir, and Genare) all show negative excursions in the stratigraphic location of the Kellwasser Event [1-3]. The δ18O values in both carbonates and/or conodont apatite likewise show negative excursions within the shallow water facies at each site, but have relatively constant signatures within the deeper water facies. 87Sr/86Sr values range from 0.70636-0.70906 at the base of the Boulongour Reservoir section and 0.70746-0.71383 at the base of the Wulankeshun section but both Sr signaures stabilize with relatively constant values closer to modeled Late Devonian seawater in deeper water and/or offshore facies. The fossil assemblages at the base of the Boulongour and Wulankeshun sections each correspond to euryhaline/brackish conditions, while microtextures in Ti-bearing phases within clastic sediments as well as isotope mixing models suggest submarine groundwater discharge signatures rather than diagenetic alteration. Preliminary framboidal pyrite distributions in these sections also show evidence for sub/dysoxic (rather than euxinic or anoxic) conditions that correspond to the stratigraphic Kellwasser interval. Positive δ13C excursions and the presence of black shales are thus not prerequisites for recognition of the Kellwasser Event, particularly in shallow water paleoenvironments that are not topographically favorable to shale accumulation and may have significant coastal groundwater or surface water inputs. [1] Suttner et al. (2014) J. of Asian Earth Sci. 80, 101-118. [2] Carmichael et al. (2014) Paleo3 399, 394-403. [3] Wang et al. (2016) Paleo3 448, 279-297.

Comparison of Glycemic Excursion in Patients with New Onset Type 2 Diabetes Mellitus before and after Treatment with Repaglinide.

PubMed

Hezarkhani, Sharabeh; Bonakdaran, Shokufeh; Rajabian, Reza; Shahini, Najmeh; Marjani, Abdoljalal

2013-01-01

Due to industrialization and sedentary life, incidence of type 2 diabetes (DM2) is increasing seriously. Repaglinide is a glucose reducing agent that predominantly reduces post-prandial glucose. Continuous glucose monitoring system (CGMS) monitors blood glucose excursions over a 3-day period. CGMS can be used as a therapeutic and diagnostic instrument in diabetics. There are not enough studies about using CGMS in DM2. The aim of this study was to determine the blood glucose excursions in patients with new onset of DM2. 10 patients with new onset of DM2 were entered to this study. As the first therapeutic management, patients received diabetic diet and moderate exercise for 3-weeks, if they did not achieve blood glucose goal (Fasting blood glucoser (FBG) <120mg/dl, 2-hour postprandial blood glucose (2hpp) <180mg/dl), were considered to undergo 3-days CGMS at baseline and after 4-weeks on Repaglinide (0.5mg three times before meals). Mean excursions of blood glucose were not different at the onset and at the end of treatment (6±4.05 VS 7.6±5.2 episodes, P=0.49). There were also no significant differences between mean duration of hypoglycemic episodes (zero VS 5.1±14.1 hours, P =0.28) and hyperglycemic episodes before and after therapy (7.6±5.2 VS 5.7±4.1, P=0.42), but mean hyperglycemia duration was significantly reduced at the end of therapy (21±26.17 VS 57.7±35.3, P=0.001). Patients experienced a mean of 0.3±0.67 episodes of hypoglycemia after therapy showed no significant difference before it (P =0.19). Mean FBG (with CGMS) was significantly lower after therapy than before it (142.9±54.31 VS 222.9±82.6, P <0.001). This study showed the usefulness of CGMS not only as a diagnostic but also as an educational and therapeutic tool that in combination with Repaglinide (with the lowest effective dose and duration) can significantly reduce FBG and glycemic excursions in DM2 patients and hypoglycemic events are low.

Euxinia prior to end-Permian main extinction at Xiaojiaba section, Sichuan Province, South China

NASA Astrophysics Data System (ADS)

Wei, H.; Algeo, T. J.; Chen, D.; Yu, H.

2013-12-01

Redox conditions in the global ocean prior to, during, and following the end-Permian mass extinction at 252.28 Ma remain contentious. Previous studies in western Australia, South China, and East Greenland have shown that photic-zone euxinia was present at least intermittently from the early Changhsingian through the Dienerian1-3. Here we report a study of organic carbon isotopes, pyrite sulfur isotopes, TOC, pyritic sulfur content, REE, and major and trace elements from the Upper Permian Xiaojiaba section in the Chaotian district of Guangyuan City, Sichuan Province, China. During the Permian-Triassic transition, this section was located on the northwestern margin of the South China Block, facing the Paleo-Tethys Ocean. Our results indicate that suboxic conditions prevailed during the Wuchiapingian and suboxic to anoxic conditions with several pulses of euxinia during the Changhsingian. δ13Corg values are mostly -28‰ to -26‰ but show three positive excursions (to -22‰) prior to the end-Permian mass extinction horizon. These positive excursions are associated with higher Spy concentrations (to ~1%). δ34Spy values are variable (from -41‰ to +5‰) but show a sharp negative excursion in the late Changhsingian (to -43.4‰) that coincided with the most positive δ13Corg values. This horizon is also associated with increases in Eu/Eu*, Baxs, ∑REE, Si, and redox-sensitive metals such as V. These patterns reflect linkage of the C and S cycles during the latest Permian, possibly in response to redox controls. The observed positive excursions in δ13Corg may be due to organic inputs from green sulfur bacteria, which exhibit a smaller photosynthetic fractionation (-12.5‰4) than eukaryotic algae. The pronounced negative excursion of δ34Spy corresponds to a sulfate-sulfide S isotope fractionation of about -60‰, suggesting a large flux of syngenetic framboidal pyrite, which would be indicative of euxinic water-column conditions. We infer that the euxinia prior to the main extinction horizon may have been caused by oceanic oxygen-minimum zone expansion and upward movement of the chemocline5. The coupled increases in Eu/Eu* and Baxs may record hydrothermal influence, possibly accompanied by increased ocean acidity and high seawater temperatures. Collectively, our results document major changes in seawater chemistry during the Changhsingian prior to the main end-Permian crisis.

The double power law in human collaboration behavior: The case of Wikipedia

NASA Astrophysics Data System (ADS)

Kwon, Okyu; Son, Woo-Sik; Jung, Woo-Sung

2016-11-01

We study human behavior in terms of the inter-event time distribution of revision behavior on Wikipedia, an online collaborative encyclopedia. We observe a double power law distribution for the inter-editing behavior at the population level and a single power law distribution at the individual level. Although interactions between users are indirect or moderate on Wikipedia, we determine that the synchronized editing behavior among users plays a key role in determining the slope of the tail of the double power law distribution.

Power and affordances: when the situation has more power over powerful than powerless individuals.

PubMed

Guinote, Ana

2008-08-01

Six studies examined how power affects responses to situational affordances. Participants were assigned to a powerful or a powerless condition and were exposed to various situations that afford different classes of behavior. Study 1 examined behavior intentions for weekdays and weekends. Studies 2 and 3 focused on responses to imaginary social and work situations. Study 4 examined planned behavior for winter and summer days. Finally, Studies 5 and 6 examined behavior and attention in the presence of situation-relevant and irrelevant information. Consistently across these studies, powerful individuals acted more in situation-consistent ways, and less in situation-inconsistent ways, compared with powerless individuals. These findings are interpreted as a result of the greater tendency for powerful individuals to process information selectively in line with the primary factors that drive cognition, such as affordances. One consequence of these findings is that powerful individuals change behavior across situations more than powerless individuals.

Iodine-to-calcium ratios in carbonates suggest a primary origin for the Precambrian Lomagundi and Shuram carbon isotope excursions

NASA Astrophysics Data System (ADS)

Hardisty, D. S.; Lu, Z.; Planavsky, N. J.; Osburn, M. R.; Bekker, A.; Lyons, T. W.

2013-12-01

Systematic increases in iodine-to-calcium ratios (I/Ca) in carbonates from both the Precambrian Lomagundi and Shuram carbonate carbon isotope (δ13Ccarb) excursion intervals suggest primary origins for these events. Iodate (IO3-), the oxidized iodine species, is the exclusive species incorporated into carbonates. The high redox sensitivity of IO3- to deoxygenation requires highly oxidizing fluids for IO3- production, making I/Ca in platform carbonates a simple indicator of the presence of oxidizing fluids in the surface ocean. Similarly, redox sensitivity makes the proxy host susceptible to diagenetic iodine loss during carbonate recrystallization in reducing pore fluids. Recent work has shown carbonates to experience near-complete iodine loss during dolomitization in the Permian, and work from our group evaluating modern and recent carbonates demonstrate the potential for diagenetic iodine loss during carbonate recrystallization. In some cases, however, such as meteoric aragonite-to-calcite transitions, oxidizing pore fluids have the potential to buffer IO3- concentrations, causing negligible alteration to primary I/Ca despite negative shifts in δ13Ccarb. These results highlight that diagenetic alterations to I/Ca and δ13Ccarb need not always be coupled, but importantly, no observed scenario promotes post-depositional addition of iodine to carbonates. This means that, independent of δ13Ccarb, systematic, stratigraphic increases in I/Ca ratios observed in the carbonate record are most easily interpreted as resulting from depositional controls such as surface ocean redox or shifts in the total marine iodine reservoir. From this, increasing I/Ca ratios coincident with rising and falling δ13Ccarb trends for the Paleoproterozic Lomagundi and Neoproterozoic Shuram events, respectively, support suggestions of a primary origin for the δ13Ccarb excursions. Significant increase in I/Ca in dolomites deposited during the Lomagundi excursion, rising from blank values in the Archean, suggest very early dolomitization in an oxidizing surface ocean promoting aerobic iodine cycling. This interpretation is consistent with earlier suggestions relating a >+10 ‰ δ13Ccarb shift to substantial organic carbon burial and associated oxygen production. Extremely negative δ13Ccarb (down to <-10 ‰) observed during the Shuram event have been linked to both diagenetic and primary mechanisms. We propose, however, that a marked increase in I/Ca ratios associated with the negative δ13Ccarb excursion in the Khufai Formation of Oman provides evidence for a primary origin for the Shuram. Such an increase could be interpreted as enhanced delivery of IO3- or total iodine from the deep ocean, perhaps driven by deep ocean ventilation and/or oxidation of a large pool of marine-derived organic matter. Overall, regardless of the individual primary controls driving increases in carbonate I/Ca during the Lomagundi and Shuram events, authigenic/diagenetic controls allowing for increased I/Ca are unlikely, suggesting a primary origin for the two largest δ13Ccarb excursions in Earth history.

Carbon Concentration Excursions in Apatite Phenocrysts from the Cerro Galan Ignimbrite: A SIMS View into the Transient pre-Eruptive Volatile History of a Supervolcano

NASA Astrophysics Data System (ADS)

Boyce, J. W.; Hervig, R. L.

2006-12-01

In nearly all igneous rock compositions, apatite is the most abundant mineral that regularly incorporates significant quantities of volatile elements into its structure, making it a potentially useful tool for exploring magmatic processing of volatiles (as well as REEs, Sr, Nd, and Pb isotopes, all of which are typically abundant in apatite). We have developed an analytical protocol that permits measurement of C, H, F, S, and Cl in ~8μm diameter regions of apatite using the Cameca 6f SIMS. A primary Cs+ beam (4-10 nA) is used in conjunction with electron gun charge-compensation to sputter negative ions from polished sections and unpolished crystal faces mounted in volatile-free indium mounts. We operated at mass resolving powers sufficient to separate all potential interferences (such as ^{31}PH and 16O2 from ^{32}S, and 17O from 16OH). Quantifying the SIMS data requires a set of standards that are 1) homogeneous at the few-micron scale; and 2) well-calibrated with multiple, reliable, independent volatile content measurements. Using values combed from the literature and other unpublished sources, we have assembled a set of apatite standards, none of which are proven to meet either criteria. Nevertheless, these materials allow us to create calibration curves for all of the volatile elements listed above. Traverses across polished basal sections of apatite phenocrysts from the ~1000 km3 Cerro Galan ignimbrite, Argentina (courtesy of C. Schirnick) yield the following results: Apatites are fluorine-rich, and contain significant and reproducible intracrystalline variations in C, H, S, and Cl. Positive carbon concentration excursions (up to 360 ppm) are factors of 2-7 greater than apatite baseline concentrations (40-60 ppm), the largest of which correlate with position in different grains. In the majority of the traverses, these carbon excursions also correlate spatially with 25-30% increases in sulfur concentration. We suggest that these dramatic increases in carbon and sulfur concentrations record a transient increase in magmatic SO4^{2- } and CO2 activities, perhaps the result of an underplating/recharge event, followed by a return to baseline magma chemistry. Hydrogen-poor rims are observed in all studied crystals, and are accompanied by chlorine-impoverished rims in a majority of the traverses, perhaps recording the pre- or syn-eruption exsolution of a vapor phase enriched in H and Cl.

From the Immoral to the Incorruptible: How Prescriptive Expectations Turn the Powerful Into Paragons of Virtue.

PubMed

Hu, Miao; Rucker, Derek D; Galinsky, Adam D

2016-06-01

Ample evidence documents that power increases unethical behavior. This article introduces a new theoretical framework for understanding when power leads to more versus less unethical behavior. Our key proposition is that people hold expectations about power that are both descriptive (how the powerful do behave) and prescriptive (how the powerful should behave). People hold descriptive beliefs that the powerful do behave more unethically than the powerless, but they hold prescriptive beliefs that the powerful should behave more ethically than the powerless. Whichever expectation-descriptive or prescriptive-is salient affects how power influences one's behavior. Three experiments demonstrate that activating descriptive expectations for power leads the powerful to cheat more than the powerless, whereas activating prescriptive expectations leads the powerful to cheat less than the powerless. The current work offers new ideas for curbing unethical behavior by those with power: focus their attention on prescriptive expectations for power. © 2016 by the Society for Personality and Social Psychology, Inc.

Surfacing behavior and gas release of the physostome sprat (Sprattus sprattus) in ice-free and ice-covered waters.

PubMed

Solberg, Ingrid; Kaartvedt, Stein

2014-01-01

Upward-facing echosounders that provided continuous, long-term measurements were applied to address the surfacing behavior and gas release of the physostome sprat ( Sprattus sprattus ) throughout an entire winter in a 150-m-deep Norwegian fjord. During ice-free conditions, the sprat surfaced and released gas bubbles at night with an estimated surfacing rate of 3.5 times per fish day -1 . The vertical swimming speeds during surfacing were considerably higher (~10 times) than during diel vertical migrations, especially when returning from the surface, and particularly when the fjord was not ice covered. The sprat released gas a few hours after surfacing, suggesting that the sprat gulped atmospheric air during its excursions to the surface. While the surface activity increased after the fjord became ice covered, the records of gas release decreased sharply. The under-ice fish then displayed a behavior interpreted as "searching for the surface" by repeatedly ascending toward the ice, apparently with limited success of filling the swim bladder. This interpretation was supported by lower acoustic target strength in ice-covered waters. The frequent surfacing behavior demonstrated in this study indicates that gulping of atmospheric air is an important element in the life of sprat. While at least part of the population endured overwintering in the ice-covered habitat, ice covering may constrain those physostome fishes that lack a gas-generating gland in ways that remain to be established.

Review of droop-controlled bi-directional inverter in conducting islanded operation of photovoltaic systems

NASA Astrophysics Data System (ADS)

Khaw, Ace Lin Yi; Wong, Jianhui; Lim, Yun Seng

2017-04-01

Global warming due to the excessive greenhouse gas emissions has led to the emergence of green technologies in Malaysia, particularly photovoltaic (PV) systems. Under the current regulatory framework, islanded operation of the PV system is not permissible. As a result, any renewable energy sources will be disconnected immediately in the event of grid outages. This practice is to ensure the safety of working personnel, as well as the customer equipment connected within the distribution networks. In addition, there is no synchronizing equipment to aid the reconnection of the islanded network to the grid. However, with the shutdown of the Distributed Generator (DG) during islanded operation, the customers are not able to utilize the available renewable energy and the number of power interruption is not improved with the renewable energy sources. Therefore, the main objective of this paper is to investigate the feasibility of the PV system in conducting islanding operation with the use of Energy Storage System (ESS). This paper also proposes a control algorithm to maintain the voltage and frequency excursion within the statutory limit by manipulating the real and reactive power flow of the ESS within the transition period between grid connected and islanding operation.

Is inflation from unwinding fluxes IIB?

NASA Astrophysics Data System (ADS)

Gautason, Fridrik Freyr; Schillo, Marjorie; Van Riet, Thomas

2017-03-01

In this paper we argue that the mechanism of unwinding inflation is naturally present in warped compactifications of type IIB string theory with local throats. The unwinding of flux is caused by its annihilation against branes. The resulting inflaton potential is linear with periodic modulations. We initiate an analysis of the inflationary dynamics and cosmological observables, which are highly constrained by moduli stabilization. For the simplified model of single-Kähler Calabi-Yau spaces we find that many, though not all of the consistency constraints can be satisfied. Particularly, in this simple model geometric constraints are in tension with obtaining the observed amplitude of the scalar power spectrum. However, we do find 60 efolds of inflation with a trans-Planckian field excursion which offers the hope that slightly more complicated models can lead to a fully consistent explicit construction of large field inflation of this kind.

Effective delayed neutron fraction and prompt neutron lifetime of Tehran research reactor mixed-core.

PubMed

Lashkari, A; Khalafi, H; Kazeminejad, H

2013-05-01

In this work, kinetic parameters of Tehran research reactor (TRR) mixed cores have been calculated. The mixed core configurations are made by replacement of the low enriched uranium control fuel elements with highly enriched uranium control fuel elements in the reference core. The MTR_PC package, a nuclear reactor analysis tool, is used to perform the analysis. Simulations were carried out to compute effective delayed neutron fraction and prompt neutron lifetime. Calculation of kinetic parameters is necessary for reactivity and power excursion transient analysis. The results of this research show that effective delayed neutron fraction decreases and prompt neutron lifetime increases with the fuels burn-up. Also, by increasing the number of highly enriched uranium control fuel elements in the reference core, the prompt neutron lifetime increases, but effective delayed neutron fraction does not show any considerable change.

Effective delayed neutron fraction and prompt neutron lifetime of Tehran research reactor mixed-core

PubMed Central

Lashkari, A.; Khalafi, H.; Kazeminejad, H.

2013-01-01

In this work, kinetic parameters of Tehran research reactor (TRR) mixed cores have been calculated. The mixed core configurations are made by replacement of the low enriched uranium control fuel elements with highly enriched uranium control fuel elements in the reference core. The MTR_PC package, a nuclear reactor analysis tool, is used to perform the analysis. Simulations were carried out to compute effective delayed neutron fraction and prompt neutron lifetime. Calculation of kinetic parameters is necessary for reactivity and power excursion transient analysis. The results of this research show that effective delayed neutron fraction decreases and prompt neutron lifetime increases with the fuels burn-up. Also, by increasing the number of highly enriched uranium control fuel elements in the reference core, the prompt neutron lifetime increases, but effective delayed neutron fraction does not show any considerable change. PMID:24976672

Conversations with the community: the Methodist Hospital System's experience with social media.

PubMed

Angelle, Denny; Rose, Clare L

2011-01-01

The Methodist Hospital System has maintained a social media presence on Facebook, Twitter, and YouTube since 2009. After initial unofficial excursions into the world of social media, we discovered that social media can be a useful tool to extend a conversation with our patients and the community at large and share our hospital's culture with a larger base of like-minded people. But with this new power comes a heightened responsibility--platforms that can potentially reach millions of viewers and readers also provide a potential for misuse that can jeopardize patient privacy and place hospitals at risk. Because of their unique restrictions, even hospitals that use the tools regularly have much left to learn about social media. With constant monitoring and stewardship and a commitment to educating staff, hospitals can effectively use social media tools for marketing and education.

Peaceful Uses of Fusion

DOE R&D Accomplishments Database

Teller, E.

1958-07-03

Applications of thermonuclear energy for peaceful and constructive purposes are surveyed. Developments and problems in the release and control of fusion energy are reviewed. It is pointed out that the future of thermonuclear power reactors will depend upon the construction of a machine that produces more electric energy than it consumes. The fuel for thermonuclear reactors is cheap and practically inexhaustible. Thermonuclear reactors produce less dangerous radioactive materials than fission reactors and, when once brought under control, are not as likely to be subject to dangerous excursions. The interaction of the hot plasma with magnetic fields opens the way for the direct production of electricity. It is possible that explosive fusion energy released underground may be harnessed for the production of electricity before the same feat is accomplished in controlled fusion processes. Applications of underground detonations of fission devices in mining and for the enhancement of oil flow in large low-specific-yield formations are also suggested.

Influence of temperature on muscle recruitment and muscle function in vivo.

PubMed

Rome, L C

1990-08-01

Temperature has a large influence on the maximum velocity of shortening (Vmax) and maximum power output of muscle (Q10 = 1.5-3). In some animals, maximum performance and maximum sustainable performance show large temperature sensitivities, because these parameters are dependent solely on mechanical power output of the muscles. The mechanics of locomotion (sarcomere length excursions and muscle-shortening velocities, V) at a given speed, however, are precisely the same at all temperatures. Animals compensate for the diminished power output of their muscles at low temperatures by compressing their recruitment order into a narrower range of locomotor speeds, that is, recruiting more muscle fibers and faster fiber types at a given speed. By examining V/Vmax, I calculate that fish at 10 degrees C must recruit 1.53-fold greater fiber cross section than at 20 degrees C. V/Vmax also appears to be an important design constraint in muscle. It sets the lowest V and the highest V over which a muscle can be used effectively. Because the Vmax of carp slow red muscle has a Q10 of 1.6 between 10 and 20 degrees C, the slow aerobic fibers can be used over a 1.6-fold greater range of swim speeds at the warmer temperature. In some species of fish, Vmax can be increased during thermal acclimation, enabling animals to swim at higher speeds.

Differentiating social and personal power: opposite effects on stereotyping, but parallel effects on behavioral approach tendencies.

PubMed

Lammers, Joris; Stoker, Janka I; Stapel, Diederik A

2009-12-01

How does power affect behavior? We posit that this depends on the type of power. We distinguish between social power (power over other people) and personal power (freedom from other people) and argue that these two types of power have opposite associations with independence and interdependence. We propose that when the distinction between independence and interdependence is relevant, social power and personal power will have opposite effects; however, they will have parallel effects when the distinction is irrelevant. In two studies (an experimental study and a large field study), we demonstrate this by showing that social power and personal power have opposite effects on stereotyping, but parallel effects on behavioral approach.

Lunar Excursion Model in Full Scale Wind Tunnel. Apollo Project. Bell Lunar Landing Training Vehicle (LLTV)

NASA Image and Video Library

1969-01-16

Concept model of the Lunar Excursion Module tested in the Full-Scale wind tunnel. -- Published in James R. Hansen, Spaceflight Revolution: NASA Langley Research Center From Sputnik to Apollo, (Washington: NASA, 1995), p. 356.-L69-670 Bell Lunar Landing Training Vehicle (LLTV): Following the crash of a sister Lunar Landing Training Vehicle at Ellington Field in Houston, Texas, the LLTV NASA 952 was sent from Houston to Langley for tests in the 30 x 60 Full Scale Tunnel. The LLTV was returned to Houston for further training use a short time later. NASA 952 is now on exhibit at the Johnson Space Center in Houston, Texas.

Variations of the earth's magnetic field and rapid climatic cooling: A possible link through changes in global ice volume

NASA Technical Reports Server (NTRS)

Rampino, M. R.

1979-01-01

A possible relationship between large scale changes in global ice volume, variations in the earth's magnetic field, and short term climatic cooling is investigated through a study of the geomagnetic and climatic records of the past 300,000 years. The calculations suggest that redistribution of the Earth's water mass can cause rotational instabilities which lead to geomagnetic excursions; these magnetic variations in turn may lead to short-term coolings through upper atmosphere effects. Such double coincidences of magnetic excursions and sudden coolings at times of ice volume changes have occurred at 13,500, 30,000, 110,000, and 135,000 YBP.

Road guide to geological points of interest on the island of Hawaii

NASA Technical Reports Server (NTRS)

Stearns, H. T.; Macdonald, G. A.; Greeley, R.

1974-01-01

This road guide briefly describes the points of geologic interest along the main roads on Hawaii. It begins at Hilo and proceeds around the island in a clockwise direction on State Route 11 to Kailua, then returns to Hilo on State Route 19 to Hilo via Waimea, with side excursions on the other principal roads. Minimum excursion time is two days, allowing only very brief time for the various stops. The return to Hilo from Waimea can be made via Route 19 along the Hamakua Coast (wet, leeward side of island, displaying typical tropical erosion) or via Route 20 over the Humuula Saddle (high, relatively dry and cool; young volcanic features).

Fracture temperature and flaw growth in nitronic 40 at cryogenic temperatures

NASA Technical Reports Server (NTRS)

Domack, M. S.

1984-01-01

The fracture resistance and fatigue response of Armco Nitronic 40 austenitic stainless steel were evaluated under cryogenic conditions. Tensile, fracture toughness and fatigue crack growth properties were measured at -275 F. The tensile yield strength was approximately 120 ksi and the fracture toughness was estimated to be 350 ksi-in /2 on the basis of fracture toughness measurements. Testing was conducted to evaluate the behavior of a simulated section of the wing of the Pathfinder 1 model subject to a load and temperature history typical of that for testing in the National Transonic Facility. The wing section model incorporated a proposed brazing technique for pressure-transducer attachment. The simulated wing section performed satisfactorily at stress levels of nearly 60 percent of the material yield strength. The brazing technique proved to be an effective method of transducer attachment under conditions of high stress levels and large temperature excursions.

Dynamic Modeling of Starting Aerodynamics and Stage Matching in an Axi-Centrifugal Compressor

NASA Technical Reports Server (NTRS)

Wilkes, Kevin; OBrien, Walter F.; Owen, A. Karl

1996-01-01

A DYNamic Turbine Engine Compressor Code (DYNTECC) has been modified to model speed transients from 0-100% of compressor design speed. The impetus for this enhancement was to investigate stage matching and stalling behavior during a start sequence as compared to rotating stall events above ground idle. The model can simulate speed and throttle excursions simultaneously as well as time varying bleed flow schedules. Results of a start simulation are presented and compared to experimental data obtained from an axi-centrifugal turboshaft engine and companion compressor rig. Stage by stage comparisons reveal the front stages to be operating in or near rotating stall through most of the start sequence. The model matches the starting operating line quite well in the forward stages with deviations appearing in the rearward stages near the start bleed. Overall, the performance of the model is very promising and adds significantly to the dynamic simulation capabilities of DYNTECC.

Fractionating dead reckoning: role of the compass, odometer, logbook, and home base establishment in spatial orientation

NASA Astrophysics Data System (ADS)

Wallace, Douglas G.; Martin, Megan M.; Winter, Shawn S.

2008-06-01

Rats use multiple sources of information to maintain spatial orientation. Although previous work has focused on rats’ use of environmental cues, a growing number of studies have demonstrated that rats also use self-movement cues to organize navigation. This review examines the extent that kinematic analysis of naturally occurring behavior has provided insight into processes that mediate dead-reckoning-based navigation. This work supports a role for separate systems in processing self-movement cues that converge on the hippocampus. The compass system is involved in deriving directional information from self-movement cues; whereas, the odometer system is involved in deriving distance information from self-movement cues. The hippocampus functions similar to a logbook in that outward path unique information from the compass and odometer is used to derive the direction and distance of a path to the point at which movement was initiated. Finally, home base establishment may function to reset this system after each excursion and anchor environmental cues to self-movement cues. The combination of natural behaviors and kinematic analysis has proven to be a robust paradigm to investigate the neural basis of spatial orientation.

Fractionating dead reckoning: role of the compass, odometer, logbook, and home base establishment in spatial orientation

PubMed Central

Martin, Megan M.; Winter, Shawn S.

2008-01-01

Rats use multiple sources of information to maintain spatial orientation. Although previous work has focused on rats' use of environmental cues, a growing number of studies have demonstrated that rats also use self-movement cues to organize navigation. This review examines the extent that kinematic analysis of naturally occurring behavior has provided insight into processes that mediate dead-reckoning-based navigation. This work supports a role for separate systems in processing self-movement cues that converge on the hippocampus. The compass system is involved in deriving directional information from self-movement cues; whereas, the odometer system is involved in deriving distance information from self-movement cues. The hippocampus functions similar to a logbook in that outward path unique information from the compass and odometer is used to derive the direction and distance of a path to the point at which movement was initiated. Finally, home base establishment may function to reset this system after each excursion and anchor environmental cues to self-movement cues. The combination of natural behaviors and kinematic analysis has proven to be a robust paradigm to investigate the neural basis of spatial orientation. PMID:18553065

Strange kinetics of bulk-mediated diffusion on lipid bilayers

PubMed Central

Campagnola, Grace; Nepal, Kanti; Peersen, Olve B.

2016-01-01

Diffusion at solid-liquid interfaces is crucial in many technological and biophysical processes. Although its behavior seems deceivingly simple, recent studies showing passive superdiffusive transport suggest diffusion on surfaces may hide rich complexities. In particular, bulk-mediated diffusion occurs when molecules are transiently released from the surface to perform three-dimensional excursions into the liquid bulk. This phenomenon bears the dichotomy where a molecule always return to the surface but the mean jump length is infinite. Such behavior is associated with a breakdown of the central limit theorem and weak ergodicity breaking. Here, we use single-particle tracking to study the statistics of bulk-mediated diffusion on a supported lipid bilayer. We find that the time-averaged mean square displacement (MSD) of individual trajectories, the archetypal measure in diffusion processes, does not converge to the ensemble MSD but it remains a random variable, even in the long observation-time limit. The distribution of time averages is shown to agree with a Lévy flight model. Our results also unravel intriguing anomalies in the statistics of displacements. The time averaged MSD is shown to depend on experimental time and investigations of fractional moments show a scaling 〈|r(t)|q〉 ∼ tqv(q) with non-linear exponents, i.e. v(q) ≠ const. This type of behavior is termed strong anomalous diffusion and is rare among experimental observations. PMID:27095275

COSMOS-e'-soft Higgsotic attractors

NASA Astrophysics Data System (ADS)

Choudhury, Sayantan

2017-07-01

In this work, we have developed an elegant algorithm to study the cosmological consequences from a huge class of quantum field theories (i.e. superstring theory, supergravity, extra dimensional theory, modified gravity, etc.), which are equivalently described by soft attractors in the effective field theory framework. In this description we have restricted our analysis for two scalar fields - dilaton and Higgsotic fields minimally coupled with Einstein gravity, which can be generalized for any arbitrary number of scalar field contents with generalized non-canonical and non-minimal interactions. We have explicitly used R^2 gravity, from which we have studied the attractor and non-attractor phases by exactly computing two point, three point and four point correlation functions from scalar fluctuations using the In-In (Schwinger-Keldysh) and the δ N formalisms. We have also presented theoretical bounds on the amplitude, tilt and running of the primordial power spectrum, various shapes (equilateral, squeezed, folded kite or counter-collinear) of the amplitude as obtained from three and four point scalar functions, which are consistent with observed data. Also the results from two point tensor fluctuations and the field excursion formula are explicitly presented for the attractor and non-attractor phase. Further, reheating constraints, scale dependent behavior of the couplings and the dynamical solution for the dilaton and Higgsotic fields are also presented. New sets of consistency relations between two, three and four point observables are also presented, which shows significant deviation from canonical slow-roll models. Additionally, three possible theoretical proposals have presented to overcome the tachyonic instability at the time of late time acceleration. Finally, we have also provided the bulk interpretation from the three and four point scalar correlation functions for completeness.

Baseline Assessment of TREAT for Modeling and Analysis Needs

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

Bess, John Darrell; DeHart, Mark David

2015-10-01

TREAT is an air-cooled, graphite moderated, thermal, heterogeneous test facility designed to evaluate reactor fuels and structural materials under conditions simulating various types of nuclear excursions and transient undercooling situations that could occur in a nuclear reactor. After 21 years in a standby mode, TREAT is being re-activated to revive transient testing capabilities. Given the time elapsed and the concurrent loss of operating experience, current generation and advanced computational methods are being applied to begin TREAT modeling and simulation prior to renewed at-power operations. Such methods have limited value in predicting the behavior of TREAT without proper validation. Hence, themore » U.S. DOE has developed a number of programs to support development of benchmarks for both critical and transient operations. Extensive effort has been expended at INL to collect detailed descriptions, drawings and specifications for all aspects of TREAT, and to resolve conflicting data found through this process. This report provides a collection of these data, with updated figures that are significantly more readable than historic drawings and illustrations, compositions, and dimensions based on the best available sources. This document is not nor should it be considered to be a benchmark report. Rather, it is intended to provide one-stop shopping, to the extent possible, for other work that seeks to prepare detailed, accurate models of the core and its components. Given the nature of the variety of historic documents available and the loss of institutional memory, the only completely accurate database of TREAT data is TREAT itself. Unfortunately, disassembly of TREAT for inspection, assay, and measurement is highly unlikely. Hence the data provided herein is intended serve as a best-estimate substitute.« less

Independently evolved upper jaw protrusion mechanisms show convergent hydrodynamic function in teleost fishes.

PubMed

Staab, Katie Lynn; Holzman, Roi; Hernandez, L Patricia; Wainwright, Peter C

2012-05-01

A protrusible upper jaw has independently evolved multiple times within teleosts and has been implicated in the success of two groups in particular: Acanthomorpha and Cypriniformes. We use digital particle image velocimetry (DPIV) to compare suction feeding flow dynamics in a representative of each of these clades: goldfish and bluegill. Using DPIV, we contrast the spatial pattern of flow, the temporal relationship between flow and head kinematics, and the contribution of jaw protrusion to the forces exerted on prey. As expected, the spatial patterns of flow were similar in the two species. However, goldfish were slower to reach maximal kinematic excursions, and were more flexible in the relative timing of jaw protrusion, other jaw movements and suction flows. Goldfish were also able to sustain flow speeds for a prolonged period of time as compared with bluegill, in part because goldfish generate lower peak flow speeds. In both species, jaw protrusion increased the force exerted on the prey. However, slower jaw protrusion in goldfish resulted in less augmentation of suction forces. This difference in force exerted on prey corresponds with differences in trophic niches and feeding behavior of the two species. The bluegill uses powerful suction to capture insect larvae whereas the goldfish uses winnowing to sort through detritus and sediment. The kinethmoid of goldfish may permit jaw protrusion that is independent of lower jaw movement, which could explain the ability of goldfish to decouple suction flows (due to buccal expansion) from upper jaw protrusion. Nevertheless, our results show that jaw protrusion allows both species to augment the force exerted on prey, suggesting that this is a fundamental benefit of jaw protrusion to suction feeders.

Using Balance Tests to Discriminate Between Participants With a Recent Index Lateral Ankle Sprain and Healthy Control Participants: A Cross-Sectional Study

PubMed Central

Pourkazemi, Fereshteh; Hiller, Claire; Raymond, Jacqueline; Black, Deborah; Nightingale, Elizabeth; Refshauge, Kathryn

2016-01-01

Context:  The first step to identifying factors that increase the risk of recurrent ankle sprains is to identify impairments after a first sprain and compare performance with individuals who have never sustained a sprain. Few researchers have restricted recruitment to a homogeneous group of patients with first sprains, thereby introducing the potential for confounding. Objective:  To identify impairments that differ in participants with a recent index lateral ankle sprain versus participants with no history of ankle sprain. Design:  Cross-sectional study. Patients or Other Participants:  We recruited a sample of convenience from May 2010 to April 2013 that included 70 volunteers (age = 27.4 ± 8.3 years, height = 168.7 ± 9.5 cm, mass = 65.0 ± 12.5 kg) serving as controls and 30 volunteers (age = 31.1 ± 13.3 years, height = 168.3 ± 9.1 cm, mass = 67.3 ± 13.7 kg) with index ankle sprains. Main Outcome Measure(s):  We collected demographic and physical performance variables, including ankle-joint range of motion, balance (time to balance after perturbation, Star Excursion Balance Test, foot lifts during single-legged stance, demi-pointe balance test), proprioception, motor planning, inversion-eversion peak power, and timed stair tests. Discriminant analysis was conducted to determine the relationship between explanatory variables and sprain status. Sequential discriminant analysis was performed to identify the most relevant variables that explained the greatest variance. Results:  The average time since the sprain was 3.5 ± 1.5 months. The model, including all variables, correctly predicted a sprain status of 77% (n = 23) of the sprain group and 80% (n = 56) of the control group and explained 40% of the variance between groups ( = 42.16, P = .03). Backward stepwise discriminant analysis revealed associations between sprain status and only 2 tests: Star Excursion Balance Test in the anterior direction and foot lifts during single-legged stance ( = 15.2, P = .001). These 2 tests explained 15% of the between-groups variance and correctly predicted group membership of 63% (n = 19) of the sprain group and 69% (n = 48) of the control group. Conclusions:  Balance impairments were associated with a recent first ankle sprain, but proprioception, motor control, power, and function were not. PMID:26967374

Using Balance Tests to Discriminate Between Participants With a Recent Index Lateral Ankle Sprain and Healthy Control Participants: A Cross-Sectional Study.

PubMed

Pourkazemi, Fereshteh; Hiller, Claire; Raymond, Jacqueline; Black, Deborah; Nightingale, Elizabeth; Refshauge, Kathryn

2016-03-01

The first step to identifying factors that increase the risk of recurrent ankle sprains is to identify impairments after a first sprain and compare performance with individuals who have never sustained a sprain. Few researchers have restricted recruitment to a homogeneous group of patients with first sprains, thereby introducing the potential for confounding. To identify impairments that differ in participants with a recent index lateral ankle sprain versus participants with no history of ankle sprain. Cross-sectional study. We recruited a sample of convenience from May 2010 to April 2013 that included 70 volunteers (age = 27.4 ± 8.3 years, height = 168.7 ± 9.5 cm, mass = 65.0 ± 12.5 kg) serving as controls and 30 volunteers (age = 31.1 ± 13.3 years, height = 168.3 ± 9.1 cm, mass = 67.3 ± 13.7 kg) with index ankle sprains. We collected demographic and physical performance variables, including ankle-joint range of motion, balance (time to balance after perturbation, Star Excursion Balance Test, foot lifts during single-legged stance, demi-pointe balance test), proprioception, motor planning, inversion-eversion peak power, and timed stair tests. Discriminant analysis was conducted to determine the relationship between explanatory variables and sprain status. Sequential discriminant analysis was performed to identify the most relevant variables that explained the greatest variance. The average time since the sprain was 3.5 ± 1.5 months. The model, including all variables, correctly predicted a sprain status of 77% (n = 23) of the sprain group and 80% (n = 56) of the control group and explained 40% of the variance between groups ([Formula: see text] = 42.16, P = .03). Backward stepwise discriminant analysis revealed associations between sprain status and only 2 tests: Star Excursion Balance Test in the anterior direction and foot lifts during single-legged stance ([Formula: see text] = 15.2, P = .001). These 2 tests explained 15% of the between-groups variance and correctly predicted group membership of 63% (n = 19) of the sprain group and 69% (n = 48) of the control group. Balance impairments were associated with a recent first ankle sprain, but proprioception, motor control, power, and function were not.

Unexpected Southern Hemisphere ionospheric response to geomagnetic storm of 15 August 2015

NASA Astrophysics Data System (ADS)

Edemskiy, Ilya; Lastovicka, Jan; Buresova, Dalia; Bosco Habarulema, John; Nepomnyashchikh, Ivan

2018-01-01

Geomagnetic storms are the most pronounced phenomenon of space weather. When studying ionospheric response to a storm of 15 August 2015, an unexpected phenomenon was observed at higher middle latitudes of the Southern Hemisphere. This phenomenon was a localized total electron content (TEC) enhancement (LTE) in the form of two separated plumes, which peaked southward of South Africa. The plumes were first observed at 05:00 UT near the southwestern coast of Australia. The southern plume was associated with local time slightly after noontime (1-2 h after local noon). The plumes moved with the Sun. They peaked near 13:00 UT southward of South Africa. The southern plume kept constant geomagnetic latitude (63-64° S); it persisted for about 10 h, whereas the northern plume persisted for about 2 h more. Both plumes disappeared over the South Atlantic Ocean. No similar LTE event was observed during the prolonged solar activity minimum period of 2006-2009. In 2012-2016 we detected altogether 26 LTEs and all of them were associated with the southward excursion of Bz. The negative Bz excursion is a necessary but not sufficient condition for the LTE occurrence as during some geomagnetic storms associated with negative Bz excursions the LTE events did not appear.

Horizontal and vertical movements of Caribbean reef sharks (Carcharhinus perezi): conservation implications of limited migration in a marine sanctuary

PubMed Central

Howey, Lucy A.; Tolentino, Emily R.; Jordan, Lance K. B.; Ruppert, Jonathan L. W.; Brooks, Edward J.

2017-01-01

Despite the ecological and economic importance of the Caribbean reef shark (Carcharhinus perezi), little data exist regarding the movements and habitat use of this predator across its range. We deployed 11 pop-up satellite archival tags on Caribbean reef sharks captured in the northeast Exuma Sound, The Bahamas, to assess their horizontal and vertical movements throughout the water column. Sharks showed high site fidelity to The Bahamas suggesting Bahamian subpopulations remain protected within the Bahamian Shark Sanctuary. Depth data indicate that Caribbean reef sharks spent a significant proportion (72–91%) of their time above 50 m in narrow vertical depth bands, which varied considerably on an individual basis. This may be indicative of high site fidelity to specific bathymetric features. Animals exhibited three broadly categorized sporadic off-bank excursions (more than 50 m excursions) down to a depth of 436.1 m, which were more frequent during the night. These deeper excursions during night may be indicative of foraging in relation to prey on mesophotic reefs, as well as diel-vertically migrating prey from the deeper meso- and bathypelagic zones. These vertical movements suggest that Caribbean reef sharks can be significant vectors of ecosystem connectivity further warranting holistic multi-system management and conservation approaches. PMID:28386422

Comparative in vivo forefoot kinematics of Homo sapiens and Pan paniscus.

PubMed

Griffin, Nicole L; D'Août, Kristiaan; Richmond, Brian; Gordon, Adam; Aerts, Peter

2010-12-01

The human metatarsophalangeal joints play a key role in weight transmission and propulsion during bipedal gait, but at present, the identification of when a habitual, human-like metatarsi-fulcrimating mechanism first appeared in the fossil record is debated. Part of this debate can be attributed to the absence of certain detailed quantitative data distinguishing human and great ape forefoot form and function. The aim of this study is to quantitatively test previous observations that human metatarsophalangeal joints exhibit greater amounts of dorsal excursion (i.e., dorsiflexion) than those of Pan at the terminal stance phase of terrestrial locomotion. Video recordings were made in order to measure sagittal excursions of the medial metatarsophalangeal joints in habitually shod/unshod adult humans and adult bonobos (Pan paniscus). Results indicate that the human first and second metatarsophalangeal joints usually dorsiflex more than those of bonobos. When timing of maximum excursion of the first metatarsophalangeal joint is coupled with existing plantar pressure data, the unique role of the human forefoot as a key site of leverage and weight transmission is highlighted. These results support hypotheses that significant joint functional differences between great apes and humans during gait underlie taxonomic distinctions in trabecular bone architecture of the forefoot. Copyright © 2010 Elsevier Ltd. All rights reserved.

Noise-induced switching near a depth two heteroclinic network and an application to Boussinesq convection.

PubMed

Ashwin, Peter; Podvigina, Olga

2010-06-01

We investigate the robust heteroclinic dynamics arising in a system of ordinary differential equations in R(4) with symmetry [Formula in text]. This system arises from the normal form reduction of a 1: squate root of 2 mode interaction for Boussinesq convection. We investigate the structure of a particular robust heteroclinic attractor with "depth two connections" from equilibria to subcycles as well as connections between equilibria. The "subcycle" is not asymptotically stable, due to nearby trajectories undertaking an "excursion," but it is a Milnor attractor, meaning that a positive measure set of nearby initial conditions converges to the subcycle. We investigate the dynamics in the presence of noise and find a number of interesting properties. We confirm that typical trajectories wind around the subcycle with very occasional excursions near a depth two connection. The frequency of excursions depends on noise intensity in a subtle manner; in particular, for anisotropic noise, the depth two connection may be visited much more often than for isotropic noise, and more generally the long term statistics of the system depends not only on the noise strength but also on the anisotropy of the noise. Similar properties are confirmed in simulations of Boussinesq convection for parameters giving an attractor with depth two connections. (c) 2010 American Institute of Physics.

Horizontal and vertical movements of Caribbean reef sharks (Carcharhinus perezi): conservation implications of limited migration in a marine sanctuary.

PubMed

Shipley, Oliver N; Howey, Lucy A; Tolentino, Emily R; Jordan, Lance K B; Ruppert, Jonathan L W; Brooks, Edward J

2017-02-01

Despite the ecological and economic importance of the Caribbean reef shark ( Carcharhinus perezi ), little data exist regarding the movements and habitat use of this predator across its range. We deployed 11 pop-up satellite archival tags on Caribbean reef sharks captured in the northeast Exuma Sound, The Bahamas, to assess their horizontal and vertical movements throughout the water column. Sharks showed high site fidelity to The Bahamas suggesting Bahamian subpopulations remain protected within the Bahamian Shark Sanctuary. Depth data indicate that Caribbean reef sharks spent a significant proportion (72-91%) of their time above 50 m in narrow vertical depth bands, which varied considerably on an individual basis. This may be indicative of high site fidelity to specific bathymetric features. Animals exhibited three broadly categorized sporadic off-bank excursions (more than 50 m excursions) down to a depth of 436.1 m, which were more frequent during the night. These deeper excursions during night may be indicative of foraging in relation to prey on mesophotic reefs, as well as diel-vertically migrating prey from the deeper meso- and bathypelagic zones. These vertical movements suggest that Caribbean reef sharks can be significant vectors of ecosystem connectivity further warranting holistic multi-system management and conservation approaches.

Evidence of Methane Outgassing During MIS3 in the Bering Sea

NASA Astrophysics Data System (ADS)

Cook, M. S.; Keigwin, L. D.

2005-12-01

There are multiple negative excursions in planktonic and benthic foraminifer δ13C in a core from 1467m in the southeast Bering Sea. These excursions occur episodically during the last glacial period, and may coincide with Dansgaard-Oeschger (D-O) events. Measured foraminifer δ13C during the excursions is as low as -14‰ and are probably the result of overgrowths of diagenetic calcium carbonate. We estimate overgrowth δ13C is -23‰, and hypothesize that the occurrence of overgrowths is associated with anaerobic oxidation of biogenic methane. The likely pressure and temperature conditions at this site and during the last glacial period were well within the zone of methane-hydrate stability, so the source of methane is probably not from destabilization of methane hydrate at this depth. The methane may have originated from increased in-situ methanogenesis resulting from greater burial of organic carbon, or from destabilization of methane hydrate at shallower sites near the methane-hydrate stability threshold. Both these scenarios could be active, consistent with the ``Clathrate Gun Hypothesis'' (Kennett et al., 2003), in which there is widespread destabilization of marine methane hydrates during D-O events, where methane gas both is oxidized within the water column and escapes to the atmosphere.

Aeroelastic airfoil smart spar

NASA Technical Reports Server (NTRS)

Greenhalgh, Skott; Pastore, Christopher M.; Garfinkle, Moishe

1993-01-01

Aircraft wings and rotor-blades are subject to undesirable bending and twisting excursions that arise from unsteady aerodynamic forces during high speed flight, abrupt maneuvers, or hard landings. These bending excursions can range in amplitude from wing-tip flutter to failure. A continuous-filament construction 'smart' laminated composite box-beam spar is described which corrects itself when subject to undesirable bending excursions or flutter. The load-bearing spar is constructed so that any tendency for the wing or rotor-blade to bend from its normal position is met by opposite twisting of the spar to restore the wing to its normal position. Experimental and theoretical characterization of these spars was made to evaluate the torsion-flexure coupling associated with symmetric lay-ups. The materials used were uniweave AS-4 graphite and a matrix comprised of Shell 8132 resin and U-40 hardener. Experimental tests were conducted on five spars to determine spar twist and bend as a function of load for 0, 17, 30, 45 and 60 deg fiber angle lay-ups. Symmetric fiber lay-ups do exhibit torsion-flexure couplings. Predictions of the twist and bend versus load were made for different fiber orientations in laminated spars using a spline function structural analysis. The analytical results were compared with experimental results for validation. Excellent correlation between experimental and analytical values was found.

Alteration of travel patterns with vision loss from glaucoma and macular degeneration.

PubMed

Curriero, Frank C; Pinchoff, Jessie; van Landingham, Suzanne W; Ferrucci, Luigi; Friedman, David S; Ramulu, Pradeep Y

2013-11-01

The distance patients can travel outside the home influences how much of the world they can sample and to what extent they can live independently. Recent technological advances have allowed travel outside the home to be directly measured in patients' real-world routines. To determine whether decreased visual acuity (VA) from age-related macular degeneration (AMD) and visual field (VF) loss from glaucoma are associated with restricted travel patterns in older adults. Cross-sectional study. Patients were recruited from an eye clinic, while travel patterns were recorded during their real-world routines using a cellular tracking device. Sixty-one control subjects with normal vision, 84 subjects with glaucoma with bilateral VF loss, and 65 subjects with AMD with bilateral or severe unilateral loss of VA had their location tracked every 15 minutes between 7 am and 11 pm for 7 days using a tracking device. Average daily excursion size (defined as maximum distance away from home) and average daily excursion span (defined as maximum span of travel) were defined for each individual. The effects of vision loss on travel patterns were evaluated after controlling for individual and geographic factors. In multivariable models comparing subjects with AMD and control subjects, average excursion size and span decreased by approximately one-quarter mile for each line of better-eye VA loss (P ≤ .03 for both). Similar but not statistically significant associations were observed between average daily excursion size and span for severity of better-eye VF loss in subjects with glaucoma and control subjects. Being married or living with someone and younger age were associated with more distant travel, while less-distant travel was noted for older individuals, African Americans, and those living in more densely populated regions. Age-related macular degeneration-related loss of VA, but not glaucoma-related loss of VF, is associated with restriction of travel to more nearby locations. This constriction of life space may impact quality of life and restrict access to services.

Load Dependency of Postural Control--Kinematic and Neuromuscular Changes in Response to over and under Load Conditions.

PubMed

Ritzmann, Ramona; Freyler, Kathrin; Weltin, Elmar; Krause, Anne; Gollhofer, Albert

2015-01-01

Load variation is associated with changes in joint torque and compensatory reflex activation and thus, has a considerable impact on balance control. Previous studies dealing with over (OL) and under loading (UL) used water buoyancy or additional weight with the side effects of increased friction and inertia, resulting in substantially modified test paradigms. The purpose of this study was to identify gravity-induced load dependency of postural control in comparable experimental conditions and to determine the underlying neuromuscular mechanisms. Balance performance was recorded under normal loading (NL, 1 g), UL (0.16 g 0.38 g) and OL (1.8 g) in monopedal stance. Center of pressure (COP) displacement and frequency distribution (low 0.15-0.5 Hz (LF), medium 0.5-2 Hz (MF), high 2-6 Hz (HF)) as well as ankle, knee and hip joint kinematics were assessed. Soleus spinal excitability was determined by H/M-recruitment curves (H/M-ratios). Compared to NL, OL caused an increase in ankle joint excursion, COP HF domain and H/M-ratio. Concomitantly, hip joint excursion and COP LF decreased. Compared to NL, UL caused modulations in the opposite direction: UL decreased ankle joint excursions, COP HF and H/M-ratio. Collaterally, hip joint excursion and COP LF increased. COP was augmented both in UL and in OL compared to NL. Subjects achieved postural stability in OL and UL with greater difficulty compared to NL. Reduced postural control was accompanied by modified balance strategies and compensatory reflex activation. With increasing load, a shift from hip to ankle strategy was observed. Accompanying, COP frequency distribution shifted from LF to HF and spinal excitability was enhanced. It is suggested that in OL, augmented ankle joint torques are compensated by quick reflex-induced postural reactions in distal muscles. Contrarily, UL is associated with diminished joint torques and thus, postural equilibrium may be controlled by the proximal segments to adjust the center of gravity above the base of support.

New high resolution geochemistry of Lower Jurassic marine sections in western North America: A global positive carbon isotope excursion in the Sinemurian?

NASA Astrophysics Data System (ADS)

Porter, Sarah J.; Smith, Paul L.; Caruthers, Andrew H.; Hou, Pengfei; Gröcke, Darren R.; Selby, David

2014-07-01

Recognising variations in the carbon isotope compositions of marine organic-rich sedimentary rocks can provide insight into changes in ocean chemistry throughout geological time. Further, identification of global excursions in the carbon isotope record has proved to be valuable as a chronostratigraphic correlation tool. This investigation presents new high-resolution organic carbon isotope data (δCorg13) for marine sediments from 2 regions in North America (Last Creek, British Columbia, Canada and Five Card Draw, Nevada, USA). The carbon isotope profiles demonstrate that there were significant differences between the carbon reservoirs at Five Card Draw and Last Creek, notably in the upper part of the Leslei Zone. The δCorg13 values show a gradual positive CIE (∼2‰) at Last Creek in the upper part of the Leslei Zone. This corresponds to a coeval positive CIE of similar duration in Dorset, UK (upper Turneri Zone; Jenkyns and Weedon, 2013), suggesting that this may be a global marine carbon isotope signature, and likely reflects a widespread increase in primary productivity during the Early Sinemurian. In addition, a brief negative CIE is observed in the uppermost Lower Sinemurian at Last Creek. This negative excursion is not recorded in the Dorset section, suggesting localised upwelling of 12C-rich bottom-waters at Last Creek. Further, the signals identified at Last Creek are not present in coeval sections at Five Card Draw, thus highlighting a significant difference between these localities. Osmium (Os) isotope data (initial 187Os/188Os values) provide a quantitative determination of the contrasting depositional environments of Five Card Draw and Last Creek (at least partially restricted with high levels of continental inundation and open-ocean, respectively). This demonstrates that basinal restriction may act as a major factor that controls isotopic stratigraphic signatures, thus preventing the identification of global or widespread regional excursions.

Chemistry of the Marlboro Clay in Virginia and Implications for the Paleocene-Eocene Thermal Maximum

NASA Astrophysics Data System (ADS)

Zimmer, M.; Cai, Y.; Corley, A.; Liang, J. A.; Powars, D.; Goldstein, S. L.; Kent, D. V.; Broecker, W. S.

2017-12-01

The Paleocene-Eocene Thermal Maximum (PETM) was a global hyperthermal ( 5ºC warming) event marked by a rapid carbon isotope excursion (CIE) of >1‰ in the marine carbonate record (e.g. Zeebe et al. Nature Geoscience 2009). Possible explanations for the CIE include intrusion of a sill complex into organic carbonate (Aarnes et al. J. Geol. Soc. 2015), dissolution of methane hydrates (Thomas et al. Geology 2002), and a comet impact event (Schaller et al. Science 2016). Here we present new data across the PETM from the VirginiaDEQ-USGS Surprise Hill (SH) core, Northumberland Co., VA. We analyzed the Marlboro Clay, a thick, kaolinite-rich clay unit that marks the initiation of the PETM in the mid-Atlantic Coastal Plain of North America, as well as units above and below it. Bulk sediment records a δ13C excursion of approximately -5‰ across the CIE, while benthic foraminifera (Cibicidoides spp.) record a synchronous excursion of approximately -4.5‰. These results are consistent with other records from the New Jersey Coastal Plain (Makarova et al. Paleoceanography 2017). The excursion coincides with an increase in magnetic susceptibility, a decrease in bulk CaCO3 content, and an 2.5‰ decrease of δ18O in both the bulk sediment and benthic foraminifera of the SH core. Pb isotope analyses of the <63 μm fraction sediments indicate a unique provenance make-up for the Marlboro Clay. The results of the study thus indicate that PETM Marlboro Clay was not generated simply by intensified weathering of the same source area as the underlying Aquia Formation and overlying Nanjemoy Formation. Any hypothesis that aims to explain the mechanism that triggered the PETM must also account for the observed distinct provenance make-up of the Marlboro Clay.

An Ocean Acidification Pulse in the Pre-onset Carbon Isotope Excursion Preceding the Paleocene-Eocene Thermal Maximum

NASA Astrophysics Data System (ADS)

Robinson, M. M.; Self-Trail, J. M.; Willard, D. A.; Stassen, P.; Spivey, W.

2015-12-01

The Paleocene-Eocene Thermal Maximum (PETM; ~55.5 Ma) is recognized globally in marine sediments by a carbonate dissolution zone, the extinction or turnover of benthic taxa, and a radiation of planktic excursion taxa, all accompanied by a rapid-onset, negative carbon isotope excursion (CIE). The cause and nature of the massive carbon release leading to this extreme climate event remains under debate. Regardless of cause, the environmental and ecosystem changes centered on the PETM are the subject of much study because they provide an analog to modern deteriorating conditions associated with the ongoing rise in atmospheric carbon dioxide. We present evidence from sediments of the South Dover Bridge core, deposited on the U.S. mid-Atlantic shelf, for an ocean acidification event in the latest Paleocene that coincides with a relatively small (-2‰) negative carbon isotope excursion (CIE) that precedes the larger (-4‰) Paleocene-Eocene CIE onset. Planktic foraminifers during this pre-onset event (POE) show post-deposition dissolution in which the coarsely cancellate and muricate wall textures characteristic of many Late Paleocene species have been dissolved away, leaving smooth, thin-walled specimens often with collapsed chambers. In addition, we document biotic responses in benthic, planktic, and terrestrial communities to the POE, including shifts in foraminifer and pollen assemblages and adaptations in calcareous nannofossil species in response to environmental perturbations. A complete recovery is evident between the POE and CIE in both the carbon isotopic signal and in the biotic response, providing additional evidence not only for a pulsed carbon release, but also for a more rapid rate of carbon release than is suggested by a single pulse over a longer period of time. The timing, nature and magnitude of ecological changes during the less extreme POE shallow water acidification event may help to define the ecological tipping point of shallow marine ecosystems.

Improving balance skills in patients who had stroke through virtual reality treadmill training.

PubMed

Yang, Saiwei; Hwang, Wei-Hsung; Tsai, Yi-Ching; Liu, Fu-Kang; Hsieh, Lin-Fen; Chern, Jen-Suh

2011-12-01

The aim of this study was to evaluate the effects of virtual reality (VR) treadmill training on the balance skills of patients who have had a stroke. A total of 14 patients with strokes were recruited and randomly assigned to receive VR treadmill or traditional treadmill training. The outcome measures that were included for the study were center of pressure (COP) sway excursion, COP maximum sway in anterior-posterior direction, COP maximum sway in medial-lateral direction, COP sway area, bilateral limb-loading symmetric index, the sway excursion values for the paretic foot (sway excursion/P), paretic limb stance time (stance time/P), number of steps of the paretic limb (number of steps/P), and contact area of the paretic foot (contact A/P) during quiet stance, sit-to-stand transfer, and level walking. There were no significant improvements in COP-related measures and symmetric index during the quiet stance, either in the VR treadmill or traditional treadmill training group (P > 0.05). However, the difference between groups after training in COP maximum sway in medial-lateral direction during the quiet stance was significant (P = 0.038). Traditional treadmill training failed to improve sit-to-stand performance, whereas VR treadmill training improved symmetric index (P = 0.028) and sway excursion (P = 0.046) significantly during sit-to-stand transfer. The changes of symmetric index between groups were markedly different (P = 0.045). Finally, both groups improved significantly in stance time/P, but only VR treadmill training increased contact A/P (P = 0.034) after training during level walking. The difference between groups during level walking was not significant. Neither traditional treadmill nor VR treadmill training had any effect on balance skill during quiet stance, but VR treadmill training improved balance skill in the medial-lateral direction better than traditional training did. VR treadmill training also improved balance skill during sit-to-stand transfers and the involvement of paretic limb in level walking more than the traditional one did.

Cosmogenic 10Be signature of geomagnetic dipole moment variations over the last 2 Ma

NASA Astrophysics Data System (ADS)

Simon, Q.; Thouveny, N.; Bourlès, D. L.; Valet, J. P.; Bassinot, F. C.; Savranskaia, T.; Duvivier, A.; Choy, S.; Gacem, L.; Villedieu, A.

2017-12-01

Long-term variations of the geomagnetic dipole moment (GDM) during periods of stable polarity and in transitional states (reversals and excursions) provide key information for understanding the geodynamo regime. Authigenic 10Be/9Be ratios (Be-ratio, proxy of atmospheric 10Be production) from marine sedimentary cores give independent and additional insights on the evolution of the geomagnetic intensity, completing information from absolute and relative paleointensity (RPI) records. Here we present new Be-ratio results obtained on several marine cores from the North Atlantic, Indian and Pacific Oceans which permit to extent into the Matuyama chron our previous 10Be-derived GDM reconstructions (Simon et al., 2016 JGR 121). Stratigraphic offsets measured between Be-ratio peaks and the corresponding RPI minima in each studied cores are assigned to (post-) detrital remanent magnetization (pDRM) effects leading to magnetization locking-in delays varying from 0 to 16 cm (up to 12 ka). All these results were compiled in order to obtain a continuous Be-ratio record covering the last 2 Ma. 10Be overproduction episodes triggered by geomagnetic dipole moment lows (GDL) linked to polarity reversals and excursions confirm the global control exerted by the GDM on cosmogenic radionuclides production. A dipole moment reconstruction derived from the Be-ratio stack (BeDiMo2Ma) was calibrated using absolute paleointensity data. This independent record completes the available paleomagnetic RPI records and permits: 1) to confront and increase the robustness and precision of GDM reconstructions; and, 2) to better constrain geomagnetic field instabilities during the mid- to late- Matuyama chron. Our new 10Be derived inventory is fully compatible with the GDL series linked to polarity reversals (Matuyama-Brunhes transition, Jaramillo and Olduvai boundaries), geomagnetic events (Cobb Mountain, Réunion) and Brunhes' excursions (e.g. Laschamp, Blake, Iceland-Basin, Big Lost). It further strengthens the occurrence of several Matuyama's excursions (Kamikatsura, Santa Rosa, Punaruu, Bjorn, Gilsa, Gardar) that were reported only from sparse locations.

Cosmogenic signature of geomagnetic reversals and excursions from the Réunion event to the Matuyama-Brunhes transition (0.7-2.14 Ma interval)

NASA Astrophysics Data System (ADS)

Simon, Quentin; Bourlès, Didier L.; Thouveny, Nicolas; Horng, Chorng-Shern; Valet, Jean-Pierre; Bassinot, Franck; Choy, Sandrine

2018-01-01

Long-term variations of the geomagnetic dipole moment (GDM) during periods of stable polarity and in transitional states (reversals and excursions) provide key information for understanding the geodynamo regime. Following several studies dealing with the Brunhes chron and the Matuyama-Brunhes transition, this study presents a new authigenic 10Be/9Be ratio (Be-ratio) record obtained from the MD97-2143 core (western Pacific Ocean). This new Be-ratio series yields a record of GDM variations covering the early Brunhes and mid to late Matuyama time period (i.e. 700-2140 ka), independently from the relative paleointensity (RPI) record obtained from the same core, that can be compared with available RPI records and stacks. Stratigraphic offsets measured between the Be-ratio peaks and the corresponding RPI minima reach 2 to 14 cm. They can be assigned to (post-) detrital remanent magnetization (pDRM) effects leading to magnetization locking-in delays varying from 2 to 12 ka in the studied core. 10Be overproduction episodes triggered by geomagnetic dipole moment lows (GDL) linked to polarity reversals and excursions confirm the global control exerted by the GDM on cosmogenic radionuclides production. A dipole moment reconstruction derived from the Beryllium-10 (BeDiMo) was compiled and calibrated using absolute paleointensity data. This independent record complements the available paleomagnetic RPI records, permitting 1) to overcome the pDRM lock-in offsets induced below the mixing layer, 2) to confront and increase the robustness and precision of GDM reconstructions and, 3) to better constrain the chronology of geomagnetic field instabilities during the mid to late Matuyama chron. Our new 10Be derived inventory is fully compatible with the GDL series linked to geomagnetic polarity reversals and events (Matuyama-Brunhes transition, Jaramillo and Olduvai subchron boundaries, Cobb Mountain, Réunion) and it strengthens the occurrence of several excursions (Kamikatsura, Santa Rosa, Punaruu, Bjorn, Gilsa, Gardar) that were until now reported from only sparse locations.

Occupant kinematics of the Hybrid III, THOR-M, and postmortem human surrogates under various restraint conditions in full-scale frontal sled tests.

PubMed

Albert, Devon L; Beeman, Stephanie M; Kemper, Andrew R

2018-02-28

The objective of this research was to compare the occupant kinematics of the Hybrid III (HIII), THOR-M, and postmortem human surrogates (PMHS) during full-scale frontal sled tests under 3 safety restraint conditions: knee bolster (KB), knee bolster and steering wheel airbag (KB/SWAB), and knee bolster airbag and steering wheel airbag (KBAB/SWAB). A total of 20 frontal sled tests were performed with at least 2 tests performed per restraint condition per surrogate. The tests were designed to match the 2012 Toyota Camry New Car Assessment Program (NCAP) full-scale crash test. Rigid polyurethane foam surrogates with compressive strength ratings of 65 and 19 psi were used to simulate the KB and KBAB, respectively. The excursions of the head, shoulders, hips, knees, and ankles were collected using motion capture. Linear acceleration and angular velocity data were also collected from the head, thorax, and pelvis of each surrogate. Time histories were compared between surrogates and restraint conditions using ISO/TS 18571. All surrogates showed some degree of sensitivity to changes in restraint condition. For example, the use of a KBAB decreased the pelvis accelerations and the forward excursions of the knees and hips for all surrogates. However, these trends were not observed for the thorax, shoulders, and head, which showed more sensitivity to the presence of a SWAB. The average scores computed using ISO/TS 18571 for the HIII/PMHS and THOR-M/PMHS comparisons were 0.527 and 0.518, respectively. The HIII had slightly higher scores than the THOR-M for the excursions (HIII average = 0.574; THOR average = 0.520). However, the THOR-M had slightly higher scores for the accelerations and angular rates (HIII average = 0.471; THOR average = 0.516). The data from the current study showed that both KBABs and SWABs affected the kinematics of all surrogates during frontal sled tests. The results of the objective rating analysis indicated that the HIII and THOR-M had comparable overall biofidelity scores. The THOR-M slightly outperformed the HIII for the acceleration and angular velocity data. However, the HIII scored slightly better than the THOR-M for the excursion data. The most notable difference in biofidelity was for the knee excursions, where the HIII had a much higher average ISO score. Only the biofidelity of the HIII and THOR-M with regard to occupant kinematics was evaluated in this study; therefore, future work will evaluate the biofidelity of the ATDs in terms of lower extremity loading, thoracic response, and neck loading.

The Late Eocene 187Os / 188Os excursion: Chemostratigraphy, cosmic dust flux and the Early Oligocene glaciation

NASA Astrophysics Data System (ADS)

Dalai, Tarun K.; Ravizza, Gregory E.; Peucker-Ehrenbrink, B.

2006-01-01

High resolution records (ca. 100 kyr) of Os isotope composition ( 187Os / 188Os) in bulk sediments from two tropical Pacific sites (ODP Sites 1218 and 1219) capture the complete Late Eocene 187Os / 188Os excursion and confirm that the Late Eocene 187Os / 188Os minimum, earlier reported by Ravizza and Peucker-Ehrenbrink [Earth Planet. Sci. Lett. 210 (2003) 151-165], is a global feature. Using the astronomically tuned age models available for these sites, it is suggested that the Late Eocene 187Os / 188Os minimum can be placed at 34.5 ± 0.1 Ma in the marine records. In addition, two other distinct features of the 187Os / 188Os excursion that are correlatable among sections are proposed as chemostratigraphic markers which can serve as age control points with a precision of ca. ± 0.1 Myr. We propose a speculative hypothesis that higher cosmic dust flux in the Late Eocene may have contributed to global cooling and Early Oligocene glaciation (Oi-1) by supplying bio-essential trace elements to the oceans and thereby resulting in higher ocean productivity, enhanced burial of organic carbon and draw down of atmospheric CO 2. To determine if the hypothesis that enhanced cosmic dust flux in the Late Eocene was a cause for the 187Os / 188Os excursion can be tested by using the paired bulk sediment and leachate Os isotope composition; 187Os / 188Os were also measured in sediment leachates. Results of analyses of leachates are inconsistent between the south Atlantic and the Pacific sites, and therefore do not yield a robust test of this hypothesis. Comparison of 187Os / 188Os records with high resolution benthic foraminiferal δ18O records across the Eocene-Oligocene transition suggests that 187Os flux to the oceans decreased during cooling and ice growth leading to the Oi-1 glaciation, whereas subsequent decay of ice-sheets and deglacial weathering drove seawater 187Os / 188Os to higher values. Although the precise timing and magnitude of these changes in weathering fluxes and their effects on the marine 187Os / 188Os records are obscured by recovery from the Late Eocene 187Os / 188Os excursion, evidence of the global influence of glaciation on supply of Os to the ocean is robust as it has now been documented in both Pacific and Atlantic records.

Beryllium isotopes as tracers of Lake Lisan (last Glacial Dead Sea) hydrology and the Laschamp geomagnetic excursion

NASA Astrophysics Data System (ADS)

Belmaker, Reuven; Stein, Mordechai; Beer, Jürg; Christl, Marcus; Fink, David; Lazar, Boaz

2014-08-01

The content of the cosmogenic isotope 10Be (t1/2=1.39 Ma) in lacustrine sediments that deposit in lakes with a large watershed is susceptible to both climate and cosmogenic production rate variations. In order to distinguish between these two controls, we measured 10Be and major elements in several sections of the annually laminated sediments of the Lake Lisan (the last Glacial precursor of the Dead Sea) that are composed of detrital sediments and primary (evaporitic) aragonites. The sections were selected to represent regional hydrology and climate as reflected by different lake configurations (level rise, drop and high-stands) and rapid change in the 10Be production rate during the Laschamp geomagnetic excursion. Since the short-lived cosmogenic “sister” of 10Be, 7Be (t1/2=53.3 d) has virtually no recycled component, the recycled 10Be in Lake Lisan detrital sediments was evaluated by measuring 7Be in their modern equivalents: modern flood suspended matter, dust and mud cracks. Our results demonstrate that although the recycled 10Be component is significant, secular variations in the 10Be concentration in Lake Lisan sediments correlate with hydrological variations and geomagnetic excursions. During periods of moderate variations in 10Be production rate, the 10Be concentration in the Lisan detrital sediments positively correlates with lake level, Al + Fe content and the (Al + Fe)/(Ca + Mg) ratio. These correlations suggest that the 10Be is adsorbed on the fine silicate component (probably clays) of the detrital laminae. The fine silicates together with carbonates were transported to Dead Sea drainage basin mainly as airborne dust that after a short residence time was washed into Lake Lisan as flood suspended matter. We suggest that preferential dissolution of carbonates in the flood suspended matter concentrated the residual fine component leading to the positive correlation between 10Be and the (Al + Fe)/(Ca + Mg) ratio. During periods of increased water discharge more carbonates were dissolved and hence the 10Be concentration in the detrital laminae increased. During periods of rapid increase in the 10Be production rate (e.g. the Laschamp excursion), 10Be showed a ∼2 fold increase, beyond the above-mentioned correlations (lake levels and Al + Fe contents). This observation suggests that Lake Lisan can serve as a potential high-resolution archive of 10Be production rate variations during periods of geomagnetic excursions.

Design Challenges of Power Systems for Instrumented Spacecraft with Very Low Perigees in the Earth's Ionosphere

NASA Technical Reports Server (NTRS)

Moran, Vickie Eakin; Manzer, Dominic D.; Pfaff, Robert E.; Grebowsky, Joseph M.; Gervin, Jan C.

1999-01-01

Designing a solar array to power a spacecraft bus supporting a set of instruments making in situ plasma and neutral atmosphere measurements in the ionosphere at altitudes of 120km or lower poses several challenges. The driving scientific requirements are the field-of-view constraints of the instruments resulting in a three-axis stabilized spacecraft, the need for an electromagnetically unperturbed environment accomplished by designing an electrostatically conducting solar array surface to avoid large potentials, making the spacecraft body as small and as symmetric as possible, and body-mounting the solar array. Furthermore, the life and thermal constraints, in the midst of the effects of the dense atmosphere at low altitude, drive the cross-sectional area of the spacecraft to be small particularly normal to the ram direction. Widely varying sun angles and eclipse durations add further complications, as does the growing desire for multiple spacecraft to resolve spatial and temporal variations packaged into a single launch vehicle. Novel approaches to insure adequate orbit-averaged power levels of approximately 250W include an oval-shaped cross section to increase the solar array collecting area during noon-midnight orbits and the use of a flywheel energy storage system. The flywheel could also be used to help maintain the spacecraft's attitude, particularly during excursions to the lowest perigee altitudes. This paper discusses the approaches used in conceptual power designs for both the proposed Dipper and the Global Electrodynamics Connections (GEC) Mission currently being studied at the NASA/Goddard Space Flight Center.

Miniature EVA Software Defined Radio

NASA Technical Reports Server (NTRS)

Pozhidaev, Aleksey

2012-01-01

As NASA embarks upon developing the Next-Generation Extra Vehicular Activity (EVA) Radio for deep space exploration, the demands on EVA battery life will substantially increase. The number of modes and frequency bands required will continue to grow in order to enable efficient and complex multi-mode operations including communications, navigation, and tracking applications. Whether conducting astronaut excursions, communicating to soldiers, or first responders responding to emergency hazards, NASA has developed an innovative, affordable, miniaturized, power-efficient software defined radio that offers unprecedented power-efficient flexibility. This lightweight, programmable, S-band, multi-service, frequency- agile EVA software defined radio (SDR) supports data, telemetry, voice, and both standard and high-definition video. Features include a modular design, an easily scalable architecture, and the EVA SDR allows for both stationary and mobile battery powered handheld operations. Currently, the radio is equipped with an S-band RF section. However, its scalable architecture can accommodate multiple RF sections simultaneously to cover multiple frequency bands. The EVA SDR also supports multiple network protocols. It currently implements a Hybrid Mesh Network based on the 802.11s open standard protocol. The radio targets RF channel data rates up to 20 Mbps and can be equipped with a real-time operating system (RTOS) that can be switched off for power-aware applications. The EVA SDR's modular design permits implementation of the same hardware at all Network Nodes concept. This approach assures the portability of the same software into any radio in the system. It also brings several benefits to the entire system including reducing system maintenance, system complexity, and development cost.

Oxygenation of the shallow ocean after the Great Oxidation Event: Geochemistry and Carbon isotopes of the Paleoproterozoic Hutuo Group in North China Craton

NASA Astrophysics Data System (ADS)

She, Z.; Yang, F.; Papineau, D.

2013-12-01

The Paleoproterozoic was known as a period of profound perturbations in marine environments and biogeochemical cycles due to the Great Oxidation Event (GOE), but the interconnections and consequences of these events remain poorly understood. We investigated the geochemistry and C isotopes of the 2.09-1.96 Ga Hutuo Group in the North China Craton (NCC) which provide evidence for the oxygenation of shallow oceans. The Hutuo Group is a >10-km-thick clastic and carbonate sequence with intercalated basalts and has undergone lower greenschist facies metamorphism. Diverse stromatolite morphotypes, ranging from small domical, conical, and columnar forms to bioherms with diameters up to 4 meters, as well as giant oncoids, are developed in the Hutuo carbonates. C isotopes of the Hutuo carbonates are characterized by a general decrease in δ13Ccarb values upsection. It consists of a lower part with δ13Ccarb ranging from 1.3 ‰ to 3.4 ‰, a middle part showing alternating positive and negative excursions of δ13Ccarb from -3.6 ‰ to 2.7 ‰, and a upper part of exclusively negative excursions with δ13Ccarb as light as -5.6 ‰. Most samples have δ18Ocarb greater than -10 ‰ and show no correlation between δ18Ocarb and δ13Ccarb. This, along with relatively low Mn/Sr ratios (mostly < 10), exclude significant diagenetic modification of the C isotopes. δ13Corg of acid-insoluble residues of stromatolitic carbonates range between -30.9 ‰ and -22.3 ‰, consistent with C-fixation with the cyanobacterial RuBisCO enzymes. Therefore, the positive excursions are probably related to burial of organic matter produced by primary producers, consistent with the ending of the 2.22-2.06 Ga Lomagundi-Jatuli event. Similar positive C isotope excursions have also been reported from contemporaneous successions elsewhere in the NCC, including the Songshan Group in Henan and Liaohe Group in Liaoning. The following negative excursions, which is consistent with the excursions reported from the 2.1-2.0 Ga Zaonega Fm in the Fennoscandian Shield, thus correspond to pulsed oxidation of biomass in an oxygenated shallow ocean. The geochemical signatures of the carbonates which show minimal contamination by terrigenous materials provides constrains on the chemistry of the Paleoproterozoic ocean. PAAS-normalized REE patterns are flat or slightly LREE-depleted with variable but slightly negative to positive shale-normalized Ce anomaly and evident Eu anomaly. The carbonates have low concentrations of U, Mo, Co and Ni, and show upsection decrease in Mo, Co and Ni abundances, consistent with increasing redox states. Metapelites from the Hutuo Group show slightly positive Eu anomaly and low Mo concentrations and U/Th ratios (0.33 - 0.10), consistent with deposition in an oxygenated environment. Collectively, the data document the fluctuations of ocean redox states and final oxygenation of the Hutuo Basin in the aftermath of the GOE. Blooms of stromatolite-building cyanobacteria caused by high nutrient availability following the GOE might have played key roles in the final oxygenation of the atmosphere and shallow oceans.

Carbon isotope chemostratigraphy and precise dating of middle Frasnian (lower Upper Devonian) Alamo Breccia, Nevada, USA

USGS Publications Warehouse

Morrow, J.R.; Sandberg, C.A.; Malkowski, K.; Joachimski, M.M.

2009-01-01

At Hancock Summit West, Nevada, western USA, uppermost Givetian (upper Middle Devonian) and lower and middle Frasnian (lower Upper Devonian) rocks of the lower Guilmette Formation include, in stratigraphic sequence, carbonate-platform facies of the conodont falsiovalis, transitans, and punctata Zones; the type Alamo Breccia Member of the middle punctata Zone; and slope facies of the punctata and hassi Zones. The catastrophically deposited Alamo Breccia and related phenomena record the ~ 382??Ma Alamo event, produced by a km-scale bolide impact into a marine setting seaward of an extensive carbonate platform fringing western North America. Re-evaluation of conodonts from the lower Guilmette Formation and Alamo Breccia Member, together with regional sedimentologic and conodont biofacies comparisons, now firmly locates the onset of the Johnson et al. (1985) transgressive-regressive (T-R) cycle IIc, which occurred after the start of the punctata Zone, within a parautochthonous megablock low in the Alamo Breccia. Whole-rock carbon isotope analyses through the lower Guilmette Formation and Alamo Breccia Member reveal two positive ??13Ccarb excursions: (1) a small, 3??? excursion, which is possibly correlative with the falsiovalis Event previously identified from sections in Western Europe and Australia, occurs below the breccia in the Upper falsiovalis Zone to early part of the transitans Zone; and (2) a large, multi-part excursion, dominated by a 6??? positive shift, begins above the start of the punctata Zone and onset of T-R cycle IIc and continues above the Alamo Breccia, ending near the punctata- hassi zonal boundary. This large excursion correlates with the punctata Event, a major positive ??13C excursion previously recognized in eastern Laurussia and northern Gondwana. Consistent with previous studies, at Hancock Summit West the punctata Event is apparently not associated with any regional extinctions or ecosystem reorganizations. In the study area, onset of the main punctata Event began after the start of both the punctata Zone and T-R cycle IIc, and preceded the Alamo impact by less than 650??k.y., as inferred from conodont biochronologic and regional rock-accumulation rate estimates. Although complicated by the heterolithic, high-energy deposits of the Alamo Breccia, the carbon isotope record of the breccia and post-breccia beds does not indicate a major impact-correlative perturbation to the carbon cycle. This study extends recognition of the punctata Event to western Laurussia, further reinforcing the potential global scale of the event and its potential importance to understanding early to middle Frasnian marine geochemistry and palaeoenvironments. Based on previous models and our observations, increased tectonic activity, increased nutrient flux to oceans, increased marine bioproductivity, widespread anoxia, and increased organic carbon burial were all likely key factors in driving the punctata Event excursion. Furthermore, periodic eustatic and regional relative sea-level rises may have played an important role in promoting organic carbon burial and in maintaining a link between the primary open-marine geochemical signal and that recorded on the shallow-marine, lower Guilmette carbonate platform. ?? 2009 Elsevier B.V. All rights reserved.

Spread of Health Behaviors in Young Couples: How Relationship Power Shapes Relational Influence

PubMed Central

Cornelius, Talea; Desrosiers, Alethea; Kershaw, Trace

2016-01-01

Introduction Romantic relationships provide a context in which partners can influence each other’s health behaviors (e.g., weight-related behaviors, substance use). Partner influence may be especially pronounced among newly parenting adolescent and young adult couples because of the desire to maintain relationships (and therefore openness to influence), and because parenting-related challenges can pose risk for uptake of unhealthy behaviors. Two understudied factors that might affect partner influence on health behaviors include relative power within the relationship and prior levels of engagement in health behaviors. Methods The current study explored longitudinal partner influence effects in a sample of newly parenting adolescent and young adult females and their male partners (Ncouples = 157) recruited from four obstetrics/gynecology clinics in Connecticut between July 2007 and February 2011. Five health behaviors in two domains were explored: weight-related behaviors (unhealthy eating, exercise) and substance use (cigarette, alcohol, and marijuana use). Relationship power and previous levels of health behaviors were examined as moderators. Variations across gender were also examined. Results Results of dyadic analysis showed partner influences for alcohol use. Partner influence depended on relationship power for eating, alcohol, and marijuana use, and on previous behavior for cigarette use. Results also varied by gender – only female-to-male influence was found for unhealthy eating and cigarette use. Higher relationship power was protective against smoking escalation for females. Discussion These results differ from previous research findings mainly on male-to-female influences. Such asymmetries may reflect traditional female dominance in food preparation, as well as shifts in power balances postpartum. Targeting relational power dynamics may buffer the spread and escalation of unhealthy behaviors in young parents, with implications for the health of both members of a couple as well as their children. PMID:27494239

Spread of health behaviors in young couples: How relationship power shapes relational influence.

PubMed

Cornelius, Talea; Desrosiers, Alethea; Kershaw, Trace

2016-09-01

Romantic relationships provide a context in which partners can influence each other's health behaviors (e.g., weight-related behaviors, substance use). Partner influence may be especially pronounced among newly parenting adolescent and young adult couples because of the desire to maintain relationships (and therefore openness to influence), and because parenting-related challenges can pose risk for uptake of unhealthy behaviors. Two understudied factors that might affect partner influence on health behaviors include relative power within the relationship and prior levels of engagement in health behaviors. The current study explored longitudinal partner influence effects in a sample of newly parenting adolescent and young adult females and their male partners (Ncouples = 157) recruited from four obstetrics/gynecology clinics in Connecticut between July 2007 and February 2011. Five health behaviors in two domains were explored: weight-related behaviors (unhealthy eating, exercise) and substance use (cigarette, alcohol, and marijuana use). Relationship power and previous levels of health behaviors were examined as moderators. Variations across gender were also examined. Results of dyadic analysis showed partner influences for alcohol use. Partner influence depended on relationship power for eating, alcohol, and marijuana use, and on previous behavior for cigarette use. Results also varied by gender - only female-to-male influence was found for unhealthy eating and cigarette use. Higher relationship power was protective against smoking escalation for females. These results differ from previous research findings mainly on male-to-female influences. Such asymmetries may reflect traditional female dominance in food preparation, as well as shifts in power balances postpartum. Targeting relational power dynamics may buffer the spread and escalation of unhealthy behaviors in young parents, with implications for the health of both members of a couple as well as their children. Copyright © 2016 Elsevier Ltd. All rights reserved.

Laterally Translating Seal Carrier For A Drilling Mud Motor Sealed Bearing Assembly

DOEpatents

Dietle, Lannie

1993-03-23

A sealing and lubrication assembly for rotating shafts intended for operation in an abrasive environment and wherein the rotary shaft may have lateral translation or excursion during its rotation. A housing receives the rotary shaft in bearing supporting relation and defines a lubricant chamber about the shaft. A seal carrier is movably positioned about the rotary shaft and has non-rotatable articulating or laterally translating relation with the housing. A high pressure rotary shaft seal is supported by the seal carrier and maintains bearing and sealing engagement with the rotary shaft during its lateral translation or excursion. The seal carrier is hydraulic force balanced and thus is not subject to pressure induced loads that might otherwise interfere with its articulation or lateral translation.

Spiral Transformation for High-Resolution and Efficient Sorting of Optical Vortex Modes.

PubMed

Wen, Yuanhui; Chremmos, Ioannis; Chen, Yujie; Zhu, Jiangbo; Zhang, Yanfeng; Yu, Siyuan

2018-05-11

Mode sorting is an essential function for optical multiplexing systems that exploit the orthogonality of the orbital angular momentum mode space. The familiar log-polar optical transformation provides a simple yet efficient approach whose resolution is, however, restricted by a considerable overlap between adjacent modes resulting from the limited excursion of the phase along a complete circle around the optical vortex axis. We propose and experimentally verify a new optical transformation that maps spirals (instead of concentric circles) to parallel lines. As the phase excursion along a spiral in the wave front of an optical vortex is theoretically unlimited, this new optical transformation can separate orbital angular momentum modes with superior resolution while maintaining unity efficiency.

Work Capability and physiological effects predictive studies. 4: In He-O2 excursions to pressures of 400- 800- 1200- and 1600 feet of sea water

NASA Technical Reports Server (NTRS)

Lambertsen, C. J. (Editor); Gelfand, R. (Editor); Clark, J. M. (Editor); Fletcher, M. E. (Editor)

1978-01-01

Experiments which exposed men in chambers, breathing helium with oxygen, to progressive increases of pressure equivalent to 400-800-1200-1600 feet of sea water (fsw) were conducted. Rates of compression and exposure to stable high pressure. Goals included: 1) determination of the specific character and time course of onset of physiological and performance decrements during the intentionally rapid compressions, and determination of rates of adaptation on reaching stable elevated pressure; 2) investigation of accelerated methods for decompression in deep saturation excursion diving; and 3) determination of competence in practical work performed in water at pressures equivalent to the extreme diving depths of 1200 and 1600 fsw.

The Neutral Islands during the Late Epoch of Reionization

NASA Astrophysics Data System (ADS)

Xu, Yidong; Yue, Bin; Chen, Xuelei

2018-05-01

The large-scale structure of the ionization field during the epoch of reionization (EoR) can be modeled by the excursion set theory. While the growth of ionized regions during the early stage are described by the ``bubble model'', the shrinking process of neutral regions after the percolation of the ionized region calls for an ``island model''. An excursion set based analytical model and a semi-numerical code (islandFAST) have been developed. The ionizing background and the bubbles inside the islands are also included in the treatment. With two kinds of absorbers of ionizing photons, i.e. the large-scale under-dense neutral islands and the small-scale over-dense clumps, the ionizing background are self-consistently evolved in the model.

Spiral Transformation for High-Resolution and Efficient Sorting of Optical Vortex Modes

NASA Astrophysics Data System (ADS)

Wen, Yuanhui; Chremmos, Ioannis; Chen, Yujie; Zhu, Jiangbo; Zhang, Yanfeng; Yu, Siyuan

2018-05-01

Mode sorting is an essential function for optical multiplexing systems that exploit the orthogonality of the orbital angular momentum mode space. The familiar log-polar optical transformation provides a simple yet efficient approach whose resolution is, however, restricted by a considerable overlap between adjacent modes resulting from the limited excursion of the phase along a complete circle around the optical vortex axis. We propose and experimentally verify a new optical transformation that maps spirals (instead of concentric circles) to parallel lines. As the phase excursion along a spiral in the wave front of an optical vortex is theoretically unlimited, this new optical transformation can separate orbital angular momentum modes with superior resolution while maintaining unity efficiency.

A Methodological Framework to Estimate the Site Fidelity of Tagged Animals Using Passive Acoustic Telemetry

PubMed Central

Capello, Manuela; Robert, Marianne; Soria, Marc; Potin, Gael; Itano, David; Holland, Kim; Deneubourg, Jean-Louis; Dagorn, Laurent

2015-01-01

The rapid expansion of the use of passive acoustic telemetry technologies has facilitated unprecedented opportunities for studying the behavior of marine organisms in their natural environment. This technological advance would greatly benefit from the parallel development of dedicated methodologies accounting for the variety of timescales involved in the remote detection of tagged animals related to instrumental, environmental and behavioral events. In this paper we propose a methodological framework for estimating the site fidelity (“residence times”) of acoustic tagged animals at different timescales, based on the survival analysis of continuous residence times recorded at multiple receivers. Our approach is validated through modeling and applied on two distinct datasets obtained from a small coastal pelagic species (bigeye scad, Selar crumenophthalmus) and a large, offshore pelagic species (yellowfin tuna, Thunnus albacares), which show very distinct spatial scales of behavior. The methodological framework proposed herein allows estimating the most appropriate temporal scale for processing passive acoustic telemetry data depending on the scientific question of interest. Our method provides residence times free of the bias inherent to environmental and instrumental noise that can be used to study the small scale behavior of acoustic tagged animals. At larger timescales, it can effectively identify residence times that encompass the diel behavioral excursions of fish out of the acoustic detection range. This study provides a systematic framework for the analysis of passive acoustic telemetry data that can be employed for the comparative study of different species and study sites. The same methodology can be used each time discrete records of animal detections of any nature are employed for estimating the site fidelity of an animal at different timescales. PMID:26261985

A Methodological Framework to Estimate the Site Fidelity of Tagged Animals Using Passive Acoustic Telemetry.

PubMed

Capello, Manuela; Robert, Marianne; Soria, Marc; Potin, Gael; Itano, David; Holland, Kim; Deneubourg, Jean-Louis; Dagorn, Laurent

2015-01-01

The rapid expansion of the use of passive acoustic telemetry technologies has facilitated unprecedented opportunities for studying the behavior of marine organisms in their natural environment. This technological advance would greatly benefit from the parallel development of dedicated methodologies accounting for the variety of timescales involved in the remote detection of tagged animals related to instrumental, environmental and behavioral events. In this paper we propose a methodological framework for estimating the site fidelity ("residence times") of acoustic tagged animals at different timescales, based on the survival analysis of continuous residence times recorded at multiple receivers. Our approach is validated through modeling and applied on two distinct datasets obtained from a small coastal pelagic species (bigeye scad, Selar crumenophthalmus) and a large, offshore pelagic species (yellowfin tuna, Thunnus albacares), which show very distinct spatial scales of behavior. The methodological framework proposed herein allows estimating the most appropriate temporal scale for processing passive acoustic telemetry data depending on the scientific question of interest. Our method provides residence times free of the bias inherent to environmental and instrumental noise that can be used to study the small scale behavior of acoustic tagged animals. At larger timescales, it can effectively identify residence times that encompass the diel behavioral excursions of fish out of the acoustic detection range. This study provides a systematic framework for the analysis of passive acoustic telemetry data that can be employed for the comparative study of different species and study sites. The same methodology can be used each time discrete records of animal detections of any nature are employed for estimating the site fidelity of an animal at different timescales.